COLUMBIA LIBRARIES OFFSITE HEALTH SCIENCES STANDARD HX64070433 RK501M351901 Principles and pract Columbia Knibersiitp in tf)c Citp of J^etu ^orfe ^^V'^i ^cfjool of Bental anb d^ral ^urgerp J^tference I.it)rarp y \^^VVv4v.y^ ^ ^ .\Utt\ 'J Digitized by tine Internet Arciiive in 2010 witii funding from Open Knowledge Commons http://www.archive.org/details/principlespractiOOmars PRINCIPLES AND PRACTICE OF Operative Dentistry BY JOHN SAYRE MARSHALL, M.D. (Syr. Univ.) DENTAL SURGEON UNITED STATES ARMY PRESIDENT ARMY EXAMINING BOARD FOR DENTAL SURGEONS PHILADELPHIA AND LONDON J. B. LIPPINCOTT COMPANY 1901 COPYKIGHT, 1901 BY J. B. LippiNCOTT Company aUECTHOTYPED AND PRINTED BY J. B. LIPPINCOTT COMPANY, PHILADELPHIA, U.S.A. ^0 tbe flUemoris of m^ more tban jFrienD THE LATE DR. JAMES W. WHITE EDITOR OF THE DENTAL COSMOS WHO THKOUGH THE NOBLENESS OF HIS CHARACTER BECAME THE INSPIRATION OP EVERY YOUNG MAN WHO CAME WITHIN THE SPHERE OF HIS INFLUENCE THIS TOLUME IS AFFECTIONATELY DEDICATED BY THE AUTHOR PREFACE. In the preparation of this volume the author has kept in mind the needs both of students and of practitioners of dental surgery. It has been his endeavor so to present the subject-matter as to give the student a comprehensive view of the principles and practice of operative dentistry, arranged in a natural and orderly sequence. This plan has also been carried out in the presentation of each individual topic, in the hope that the student will thereby be helped in his understanding of the various phases of each department of the subject and likewise taught to be me- thodical in his studies and operations. It is also hoped that the dental practitioner will find in the work material which will assist him in his investigations of those jjathologic conditions of the teeth and their con- tiguous parts, and the surgical methods employed in their treatment, that occupy so large a part of his time, energy, and skill. The methods of constructing artificial crowns and bridge- work have not been included in this volume, because in the opinion of the author they properly belong to the department of prosthetic dentistry. The subject of orthodontia has also been excluded, for the reason that this branch has assumed the proportions of a separate specialty, and would therefore occupy more space than could be given to it in a work of this size and character. The author desires to acknowledge his great indebtedness to his friend Dr. Vida A. Latham, of Chicago, for her valuable services in the prepara- tion of numerous original and interesting photomicrographs of normal and pathologic dental tissues and of bacteriologic specimens ; also to his friends Dr. E-. E. Andrew^, of Cambridge, Massachusetts, and Mr. James S. Shearer, of Bay City, Michigan, for the use of a number of original photo- micrographs from their valuable collections ; to Dr. W. D. Miller, of Berlin, Germany ; to Dr. J, Leon Williams, of London, England ; to Dr. Filandro Vincentini, of N"aple3, Italy ; to Dr. Matt H. Cryer, of Philadel- phia, and to Dr. Frederick B. Noyes, of Chicago, for the privilege of reproducing and using several illustrations from the published accounts of their investigation^. The author also acknowledges the courtesy extended by Dr. Wilbur F. Litch, Dr. G. V. Black, and the publishers of the "American System of VI PREFACE. Dentistry ;" by Dr. Edward 0. Kirk and the publishers of the "American Text- Book of Operative Dentistry ;" by the late Dr. Henry H. Burchard and the publishers of his "Dental Pathology, Therapeutics, and Pharma- cology ;" by Mr. Charles Tomes, F.R.C.S, , of London, England; by the S, S. White Dental Manufacturing Company, and by others, for the privi- lege of reproducing many valuable illustrations. Acknowledgment is also due to his friend Dr. Bertha. E. Bush, of Chicago, for much valuable and time-saving assistance in reading and correcting the proofs. Chicago, August 1, 1901. CONTENTS. CHAPTER I. PAGE Classification and Descriptive Anatomy of the Teeth 1 Number and Classification of the Teeth— Descriptive Anatomy of the Teeth — Architectural Design of the Teeth — The Incisors — The Cuspids — The Bicuspids — The Molars— The Deciduous Teeth. CHAPTER II. Origin, Development, and Morphology of the Teeth 26 Evolution of Epithelial Tissue — Evolution of the Jaws — Evolution of the Teeth. CHAPTER III. Histology of the Dental Tissues 34 Enamel — Striae — Chemic Composition of Enamel — Calcification of Enamel — Stratum Intermedium — Blood-Supply of the Enamel-Organ — Dentin — Matrix — Dentinal Tubuli, Sheaths, and Fibrils — Interglobu- lar Spaces — Development of the Root — Dentinification — Cementum — Cementification — Chemical Composition of Calcified Tissues — Nas- myth's Membrane — The Teeth-Pulp — The Peridental Membrane- The Gums. CHAPTER IV. Eruption op the Teeth 59 Deciduous Teeth — The Eruptive Process — Growth of the Jaw — Morbid Primary Dentition — Exuviation or Shedding of the Deciduous Teeth — Eruption of the Permanent Teeth. CHAPTER V. Bacteriology of the Mouth 83 Parasites — Classifications— Mouth Bacteria Proper — Bacteria which affect the Integrity of the Dental Tissues — Sterilization of Hands and Instruments — Technique of SteriHzation. CHAPTER VI. Examination of the Teeth and Mouth 107 Position of Patient and Operator — Instruments used in Examinations — The Examination. VIU CONTENTS. CHAPTER VII. PAGE Dental Caries 115 Distribution — Results of the Examination of Ancient Crania — Preva- lence of Dental Caries— Etiology — Constitutional Predisposing Causes — Local Predisposing Causes. CHAPTER VIII. Dental Caries (Continued) 135 Theories of Caries — Caries of Enamel — Caries of Dentin — Penetration of Caries — Caries of Cementum. CHAPTER IX. Dental Caries (Continued) 161 Varieties — Stages — Symptoms — Diagnosis — Prognosis. CHAPTER X. Treatment of Caries. Prophylaxis 166 Cleanliness of the Mouth and Teeth — Dentifrices — Aj|J;iseptics. CHAPTER XI. Treatment of Caries ( Continued) 171 Medication — Excision. CHAPTER XII. Treatment op Caries ( Continued) 174 Methods of Separation of Contiguous Teeth — Exclusion of Moisture. CHAPTER XIII. Hypersensitive Dentin 184 Causes of Hypersensitive Dentin — Treatment— Palliative Treatment — Chemical Treatment — Heated Air, etc. CHAPTER XIV. Cataphoresis 193 Osmosis — Anodal Electrolysis — Cathodal Electrolysis — The General Principles or Laws which govern the Generation and Transmission of Electricity — Rheostats ; Current Selectors ; Current Controllers — Electrococaine Anaesthesia — Method of Administration — General Anaesthesia. CHAPTER XV. The Classification op Cavities 217 Simple Cavities upon Exposed Surfaces — Simple Approximal Cavities — Compound Cavities. CONTENTS. ■ ix CHAPTER XVI. PAGE Pkepakation of Cavities 234 Opening the Cavity — Removing Decay — Retentive Shaping — Forming Cavity Margins. CHAPTER XVII. Teeatment of Caries by Obturation, or Filling 250 Filling-Materials and their Introduction — Non-Plastic Materials — Physical Characteristics of Gold — Properties of Gold-Foil — Non- Cohesive Foil — Cohesive Foil — Plugging Instruments — Crystal or Sponge Gold — Gold-and-Platinum Foil — Annealing. CHAPTER XVIII. Considerations in Filling Special Classes of Cavities 272 Simple Cavities upon Exposed Surfaces — Simple Approximal Cavi- ties — Compound Cavities — Matrices — Tin-Foil — Tin and Gold — Finish- ing Fillings — Repairing Defective Gold Fillings. CHAPTER XIX. Plastic Filling-Materials. Amalgam 296 The Nature and Properties of Amalgam — Chemic Relations — Com- position of Alloys — Making Dental Alloys. CHAPTER XX. Manipulation and Introduction op Plastic Filling-Materials 321 Especial Uses of Amalgam — Mixing Amalgams — Introduction of Amal- gams—Copper Amalgam — Gutta-Percha — Zinc Cements — Varnishes. CHAPTER XXI. Inlays 346 Metal — Porcelain— Glass— Methods of Manipulation. CHAPTER XXII. Denudation or Erosion of the Teeth, and Attrition or Abrasion 359 Causes — Pathology — Treatment. CHAPTER XXIII. Diseases and Injuries of the Dental Pulp and Their Treatment 373 Hypersemia of the Dental Pulp— New Formations — Calcifications. X CONTENTS. CHAPTER XXIV. PAGE Inflammation of the Dental Pulp 397 Table of Inflammatory Phenomena— Inflammation of the Pulp— Sup- puration of the Dental Pulp— Chronic Inflammation of the Dental Pulp. CHAPTER XXV. Exposure of the Dental Pulp and its Treatment 416 Secondary Dentin, or Dentin of Repair — Devitalization and Extirpa- tion of the Pulp — Physical Effects of Arsenic upon the Pulp. CHAPTER XXVI. Pulpless Teeth and Filling Pulp-Canals 431 Preparation and Treatment of Pulp-Canals — Materials Employed for Filling Pulp-Canals and Methods of Introduction— Mummification of the Pulp. CHAPTER XXVII. Bleaching Discolored Teeth 446 Preparation of the Tooth for Bleaching — Method of Bleaching — Chlo- rine Methods — Truman Method — Dioxide Methods — Sulphurous An- hydride Method — Cataphoric Method. CHAPTER XXVIII. Diseases op the Pericementum 459 Pericementitis — Subacute and Chronic Pericementitis — General Non- Septic Pericementitis — Tubercular Pericementitis — Scorbutic Perice- mentitis — Mercurial Pericementitis. CHAPTER XXIX. Dento- Alveolar Abscess 474 Causes — Varieties -Pathology — Formation of Pus — Location — Chronic Dento- Alveolar Abscess — Treatment. CHAPTER XXX. Replantation op the Teeth 490 Indications calling for Replantation — Persistent Alveolar Abscess. CHAPTER XXXI. Transplantation and Implantation op the Teeth 494 Transplantation of Teeth — Implantation of Teeth — Requirements for the Operation — Method of Operation. CONTENTS. XI CHAPTER XXXII. PAGE Dislocation of the Teeth 501 Partial and Complete Dislocations — Treatment— Prognosis. CHAPTER XXXIII. Fractukes of the Teeth 505 Simple, Compound, and Comminuted Fractures — Treatment — Union of Fractured Teeth. CHAPTER XXXIV. Resokption of the Roots of Permanent Teeth 509 Causes — Pathology — Symptoms and Diagnosis— Prognosis — Treatment. CHAPTER XXXV. Hypercementosis 513 Causes — Pathology — Inostosis — Symptoms and Diagnosis — Treatment. CHAPTER XXXVI. Necrosis of the Teeth 518 Causes — Partial Necrosis — Treatment. CHAPTER XXXVII. Deposits upon the Teeth. Green Stains. Calcic Deposits 521 Composition of the Saliva— Salivary Calculus— Varieties — Treatment — Scalers. CHAPTER XXXVIII. Pyorrhoea Alveolaris 530 Constitutional Origin of the Disease— Local Origin of the Disease — Bacterial Origin of the Disease — Ptyalogenic Calcic Pericementitis : Causes — Pathology and Morbid Anatomy — Symptoms and Diagnosis — Prognosis — Treatment. . CHAPTER XXXIX. Hematogenic Calcic Pericementitis 550 Causes — Varieties — Pathology and Morbid Anatomy — Symptoms and Diagnosis — Prognosis — Treatment. CHAPTER XL. Phagedenic Pericementitis 568 Causes — Pathology — Symptoms and Diagnosis — Prognosis — Treatment. xii CONTENTS. CHAPTER XLI. PAGE Anaesthetics, Local and General 578 Local Ansesthetics — Anaesthesia by the Local Abstraction of Heat — Richardson's Method — Letamendi's Method — Anaesthesia by the Local Narcotic Effect of Drugs — Cocaine— Eucaine — Chloretone — General Anajsthetics — Nitrous Oxide — Hewitt's Method — Examination of the Physical Condition of the Patient — Precautions against Accidents— Administration of Ether. CHAPTER XLIL Extraction of Teeth 595 Indications which call for the Extraction of Teeth — General Condi- tions Unfavorable to Extraction — Instruments used in the Operation of Extracting — Selection of the Proper Instruments for the Extraction of the Various Classes of Teeth, their Proper Adjustment, and the Kind and Direction of the Force applied — Extraction of the Roots of Teeth — Difficulties, Complications, and Accidents. LIST OF ILLUSTRATIONS. PLATES. PLATE PAGE I. Varicosed enamel-rods, magnified 36 II. Varicosed enamel-rods, very highly magnified 37 III. Normal dentin showing tubuli in cross-section, highly magnified 44 IV. Normal dentin showing tubuli in longitudinal section, highly magnified 45 V. Leptothrix racemosa, early stages 96 VI. Leptothrix racemosa, later stages , 97 VII. Abnormal root-canals 435 FIGURES. FIG. 1. Vertical section of inferior maxilla and teeth of mole, X 15 2 2. Deciduous teeth of the left side 2 3. Permanent teeth of the right side 2 4. Structures of a tooth 2 5. Occlusion of the teeth 3 6. Superior left central incisor, labial surface 3 7. Superior right central incisor, labial surface 3 8. Superior left central incisor, labial surface 6 9. Superior left central incisor, lingual surface 6 10. Superior left central incisor, mesial surface 6 11. Superior left central incisor, distal surface . 6 12. Superior right lateral incisor, labial surface 7 13. Superior right lateral incisor, lingual surface 7 14. Superior lateral incisor with exaggerated cervical ridge 7 15. Superior right lateral incisor, mesial surface 7 16. Superior right lateral incisor, distal surface 7 17. Inferior right central incisor, labial surface 8 18. Infei'ior right central incisor, lingual surface 8 19. Inferior right central incisor, mesial surface 8 20. Inferior right central incisor, distal surface 8 21. Inferior right lateral incisor, labial surface 9 22. Inferior right lateral incisor, lingual surface 9 23. Inferior right lateral incisor, mesial surface 9 24. Inferior right lateral incisor, distal surface 9 25. Superior right cuspid, labial surface 10 26. Superior right cuspid, lingual surface 10 27. Superior right cuspid, mesial surface ■. 10 28. Superior right cuspid, distal surface 10 29. Inferior right cuspid, labial surface 11 30. Inferior right cuspid, lingual surface 11 31. Inferior right cuspid, mesial surface 11 32. Inferior right cuspid, distal surface 12 33. Superior right first bicuspid, buccal surface 12 34. Superior right first bicuspid, lingual surface 12 35. Superior right first bicuspid, mesial surface. . . : 12 36. Superior right first bicuspid, distal surface 12 xiii XIV LIST OF ILLUSTRATIONS. FIG. PAGE 37. Superior right first bicuspid, morsal surface 13 38. Superior right second bicuspid, buccal surface 13 39. Superior right second bicuspid, hngual surface 13 40. Superior right second bicuspid, mesial surface 13 41. Superior right second bicuspid, distal surface 14 42. Superior right second bicuspid, morsal surface 14 43. Inferior right first bicuspid, buccal surface 14 44. Inferior right first bicuspid, lingual surface 14 45. Inferior right first bicuspid, mesial surface 15 46. Inferior right first bicuspid, distal surface 15 47. Inferior right first bicuspid, morsal surface 15 48. Inferior right second bicuspid, morsal surface 15 49. Inferior right second bicuspid, buccal surface 16 50. Inferior right second bicuspid, lingual surface 16 51. Inferior right second bicuspid, mesial surface 16 52. Inferior right second bicuspid, distal surface 16 53. Superior right first molar, buccal surface 17 54. Superior right first molar, lingual surface 17 55. Superior right first molar, mesial surface 17 56. Superior right first molar, distal surface 17 57. Superior right first molar, morsal surface 18 58. Superior right second molar, buccal surface 18 59. Superior right second molar, lingual surface 18 60. Superior right second molar, mesial surface 18 61. Superior right second molar, distal surface 19 62. Superior right second molar, morsal surface 19 63. Superior right third molar, buccal surface 19 64. Superior right third molar, lingual surface 19 65. Superior right third molar, mesial surface 20 66. Superior right third molar, distal surface 20 67. Superior right third molar, morsal surface 20 68. Inferior right first molar, buccal surface 20 69. Inferior right first molar, lingual surface 21 70. Inferior right first molar, mesial surface 21 71. Inferior right first molar, distal surface 21 72. Inferior right first molar, morsal surface 21 73. Inferior right second molar, buccal surface 22 74. Inferior right second molar, lingual surface 22 75. Inferior right second molar, mesial surface 22 76. Inferior right second molar, distal surface 22 77. Inferior right second molar, morsal surface 23 78. Inferior right third molar, buccal surface 23 79. Inferior right third molar, lingual surface 23 80. Inferior right third molar, mesial surface 23 81. Inferior right third molar, distal surface 24 82. Inferior right third molar, morsal surface 24 83. Deciduous teeth of the left side 25 84. Graafian follicles, or ova, in various stages of development, X 80 26 85. Division of mammal ovum 27 86. 87, 88. Transverse section of embryo of chick 26 89, 90. Vertical sections of human skin 27 91. Squamous epithelium from buccal cavity, X 162 27 92. Longitudinal section of lip of a kitten 27 93. Transverse section of hairs of scalp, X 50 28 94. Epithelial layer of the mucous membrane 28 95. 96. Columnar epithelial cells, X 670 28 LIST OF ILLUSTRATIONS. XV FIG. PAGE 97. Goblet-cells, X 500 28 98. Section of jaw of rabbit embryo 28 99. First rudiments of a hair from human embryo 28 100. Lower jaw of human embryo, X 80 29 101. Vertical section of skin, showing bulbous ends of hairs, X 55 29 102. Head of human embryo 29 103. Vertical section through head of human foetus, X 80 29 104. Lower jaw of human foetus, X 80 29 105. Involution of the Malpighian stratum 30 106. Lower jaw of human embryo, X 75 30 107. Vertical section of epithelial cord, or primitive enamel-organ, X 300 30 108. Cross-section of epithelial cord, X 300 30 109. Primitive epithelial cord, X 45 30 110. Section through lower jaw of embryo mouse 31 111. Evolution of dental follicle (ninth week), X 70 31 112. Developing human cuspid 31 113. Follicle of human molar (eleventh week), X 50 31 114. Human embryo (twelfth week) 32 115. Vertical section of human molar at junction of enamel-organ with dentin papilla, X 300 32 116. Vertical section of incisor of human foetus 32 117. Oblique section of a dental follicle 32 118. Vertical section of human molar, early stage of calcification, X 90 32 119. Vertical section of cuspid of human foetus, budding of primitive epithelial cord, X 70 32 120. Vertical section of human foetal maxilla, X 70 33 121. Vertical section of human foetal incisor, X 50 33 122. Section of human developing tooth 33 123. Section of dental folhcle of cat, X 9 33 124. Vertical section of cuspid, human foetus, X 50 33 125. Vertical section of molar, human foetus, X 70 33 126. Section of dental follicle, first layers of ameloblasts and odontoblasts, X 100. . 34 127. Section of f cetal femur, showing odontoblasts, X 109 34 128. Forming dentin, showing odontoblasts, X 1900 35 129. Enamel-cells, with nuclei 35 130. Dentinal sheaths 36 131. 132. Enamel-columns, highly magnified 36 133. Developing molar, ends of enamel-rods, X 1000 36 134, 135. Sections of enamel-rods, odontoblasts, and dentin 37 136. Section of enamel, striations of Retzius, X HO 38 137. Section of dental follicle, first layer of ameloblasts, X 325 38 138. Teased section of developing molar, showing ameloblasts, X 1000 38 139. Developing enamel, Tomes's processes 38 140. Section of developing human molar, X 1000 39 141. 142, Section of developing tooth, ameloblasts highly magnified 39 143. Transverse section of developing tooth, X 275 39 144. Developing tooth of embryo lamb, X 105 40 145. Section of human foetal incisor ; blood-supply of enamel-organ 40 146. Section of dental follicle of rat, papillary layer, X 90 40 147. Section of forming enamel (rat), X 325 40 148. Section of incisor of rat, X 80 41 149. Ground section of developing tooth of rat, X 97 41 150. 151, 152. Forming enamel, calcoglobulin, formation of enamel-rods 41, 42 153. Longitudinal section of incisor 42 154. Longitudinal section of inferior molar 42 155. Section of root of bicuspid, radiation of dentinal tubuli 43 Xvi LIST OF ILLUSTRATIONS. FIG. PAGE 15G. Dentinal tubuli at dento-enauiel junction, X 760 43 157, 158. Sections of root, parallel to dentinal canals 43 159. Section of dentin and enamel, tubuli entering the enamel 44 160. Section of developing tooth, dentinal fibres passing from dentin to enamel, X 1000 44 161. Dentinal sheaths, X 273 45 162. Section of enamel and dentin, interglobular spaces, X 50 45 163. Section of enamel and dentin, interglobular spaces, X HO 48 164. Section of dentin and cementum, X 97 48 165. Section of enamel and dentin, incremental lines, ,X 500 48 166. Vertical section of foetal face, X 7 ■ 48 167. Section of human lower jaw, X 9 49 168. Section of developing human cuspid, X 100 49 169. Teased section of developing molar, X 1000 49 170. Truncated odontoblasts and fibril cells 49 171. Section of tooth-follicle, nuclei of odontoblasts, etc., X 325 50 172. Odontoblasts 50 173. 174. Sections of bone, X 60 51 175, 176. Sections of cuspidati, magnified 52 177, 178. Sections of molars, magnified 52 179. Section of root of tooth and alveolus, X 80 53 180. Section of alveolar process and cuspid, X 100 53 181. Developing bone from scapula, X 50 53 182. Section of enamel and Nasmyth's membrane, X 250 54 183. 184. Sections of normal pulp-tissue, X 143 54 185, 186, 187. Sections showing blood-supply of the pulp 55 188. Injected dental pulp, X 8 56 189. Nerves of dental pulp 56 190. Pericementum and alveolar process between teeth, X 100 56 191. Section through pulp-chamber of cuspid 56 192. Periosteum surrounding ulnar and radius, X 13 • 56 193. 194. Peridental membrane of forming tooth 56 195. Section through alveolar process, X 30 57 196. Section of root of tooth in situ 57 197. Blood-vessels and nerves entering at base of dental follicle, X 96 57 198. Section of pericementum in situ, X 408 57 199. 200. Sections of peridental membrane, highly magnified 58 201. Section of jaw through alveolar process, X 60 59 202. Section of dental follicle and mucous membrane, X 26 59 203. Glands of Serres, X 50 59 204. Epithelial layer of embryonic mucous membrane 59 205. Section of jaw, showing forming root, X 15 60 206. Follicles of permanent teeth at period of eruption of primary teeth, X 22 ... . 60 207. Lower jaw of foetal mouse, X 80 61 208. 209. Section of erupting tooth of mouse, area of resorption at cusp, magni- fied 61 , 62 210. Vertical section of human cuspid, X 75 62 211. Kami at various ages 63 212. Jaws of a young child 64 213. 214. Sections of jaw of embryo cat, showing deciduous tooth and follicle of permanent tooth 64 215. First and second dentition 66 216-220. Eruption of teeth 71 221. Gum-lancet 72 222. Curved scissors 73 223. Peculiar exuviation of a kitten's tooth, X 35 76 LIST OF ILLUSTKATIONS. xvil FI*'- PAGE 22-4. Absorbent organ and portion of dentin, X 65 76 225. Calcification and decalcification of teeth 78 226. Fruit mould, X 130 84 227. Forms of bacteria 85 228. Various forms of yeast fungi 86 229. Torula, or yeast fungi 84 230. Bacterium typhosus, X 1000 88 231. Bacillus pestis and blood-cells of rat, X iOOO 88 232. Pneumococcus, capsule form, X 1200 88 233. Diplococcus pneumoniae, X 1000 88 234. Streptococcus pyogenes, X 1000 89 235. Streptococcus in pyemia after erysipelas, X 660 89 236. Bacteria in pus, X 700 < 89 237. Bacillus tuberculosis, X 1000 89 238. Flagellated spirillee and vibrio, X 2100 90 239. Bacillus of hog cholera, X 1000 90 240. Staphylococcus pyogenes, X 1000 91 241. Streptococcus pyogenes, X 1000 91 242. Streptococcus hominis, X 21 8. 75 91 243. Leptothrix buccalis, X 193.75 92^ 244. Mouth bacteria (diplococci, leptothrix) 92 245. Bacillus buccalis maximus, 1800 : 1 93 246. Spirochseta dentium (denticola) and leptothrix threads, X 1000 94 247. Spirochseta dentium, showing flagella, X 1000 94 248. Leptothrix gigantea, from dog, X 750 94 249. 250. Leptothrix gigantea, X 1000 95 251. Micro-organisms from enamel surface 100 252-258. Leptothrix racemosa, fructification heads, etc 100' 259. Instrument-sterilizer , 105 260, 261. Dental mirrors 105, 109' 262-264. Magnifying-glasses 110 265. Explorers Ill 266. Electric mouth-lamp Ill 267. Parr's universal separator 112 268. Perry's two-bar separators 113 269. Syphilitic teeth 129^ 270. 271. Caries following crack in enamel, X 95 132 272, 273. Caries of enamel and dentin 156 274. Undermining caries of enamel 157 275. Section of a molar crown with caries 157 276-293. Infected dentin and dentinal tubules 157-161 294. Section of a molar showing stages of caries 162 295. Corundum disks 173 296. 297. Tooth-separators 176 298, 299. Napkin clamps 178 300. Rubber dam applied 180 301. Rubber-dam holder 180' 302. Ivory clamps 181 303. Ottolengui's clamp applied 181 304. How's cervix screw-clamp 181 305. Elliot's clamp and forceps 182 306. Rubber-dam applier ' 182 307. Ainsworth's rubber-dam punch 182 308. Sizes of holes in rubber dam 183 309. Depressed rubber dam 183 310. 311. Denham coffer-dam shield 183- xviii LIST OF ILLUSTEATIONS. FIG. PAGE 312. Mirror 183 313, 314. Hot-air syringes 189 315. Improved electric hot-air syringe 190 316. Jewell graphite rheostat 205 317. Weston's niillianipereoieter 207 318. Cataphoric electrodes 208 319. Cataphoric outfit without milliamperemeter 209 320. Arrangement of apparatus for cataphoric work 210 321. Syringe electrode 213 322. Flexible face-piece for inhalers 215 323. Allis's ether inhaler 216 324-344. Simple cavities in teeth 218-225 345, 346. Small chisels and hatchet excavators 226 347. Cavity prepared for filling 227 348, 349. Cavity near morsal edge of cuspid 227 350-353. Cavities on mesial and distal surfaces of bicuspids and molars 228 354-366. Compound cavities 229-233 367. Water-syringe 241 368, 369. Burs for opening small cavities 241, 242 370, 375. Cleavage of enamel 242, 249 371, 372. Chisels 242, 243 373. Excavators 245 374. Instruments for setting screw-posts 248 376. Crowns restored with cohesive gold-foil 257 377. Cyhnders of gold-foil 258 378. Foil-carriers 258 379. Cylinders and mats being introduced into a cavity 258 380. 381. Bing pluggers ; Butler pluggers 259, 260 382. Herbst burnishers 262 383, 384. Varney pluggers ; Webb pluggers 264 385. Steel mallets 264 386, 387. Darby-Perry pluggers ; Chappell pluggers 265 388. Royce plugger-points 265 389. Snow & Lewis automatic plugger 266 390. 391. Abbott automatic mallet 267 392, 393. Bon will electro-magnetic and mechanical mallets 267 394, 395. Electric gold annealers 271 396. Gum retractor 272 397-401. Clamps for keeping rubber dam in position 272, 273 402-411. Filling simple cavities upon exposed surfaces 273-276 412-414. Filling simple approximal cavities 277, 278 415-429. Filling compound cavities 279-282 430-433. Matrices and forceps 284, 285 434. Hand-burnishers 288 435, 436. Engine-burnishers ; disk burnishers 289 437. Plug-finishing burs 289 438. Wood polishing-points 289 439. Corundum points and wheels 290 440. Arkansas, Hindostan, and Scotcli stones 290 441. Soft rubber i^olishing-cups 290 442^44. Plug-trimmers and. finishing files 291 445. Right and left plug-finishing files 292 446. Thickened- rim sand-paper disks 292 447. Disk mandrels 293 448. An inoculated gelatin plate showing antibacteric effects of copper amalgam ... 313 449. Creager loop matrices 322 LIST OF ILLUSTRATIONS. xix TIG. PAGE 450. Flagg wafering pliers 324 451. Glass mortar and pestle 324 452. 453. Amalgam-carriers 326 454. Flagg amalgam instruments , 326 455. Kirk's instruments for plastics 327 456. Revised set of amalgam instruments 327 457. Heating spoon — cone-socket handle 329 458^61. Built-up molar crowns 330 462. Flagg' s gutta-percha softener and tool-heater 354 463. How's thermoscopic heater 335 464. 465. Glass mixing-slab ; spatulas 338 466. Details of process for making cast filling for incisor 347 467^70. Restoration of incisors and molars by cast fillings 348 471, 472. Bridge-work 349 473, 474. Porcelain stoppers ; inlay rods 350 475, 476. Inlay trephines and burs 351 477, 478. Electric oven ; electric furnace 352 479, 480. Erosion of teeth 365 481, 482. Erosion of teeth from gout 366 483. Abrasion by tooth-brush 371 484, 485. Hypersemia of dental pulp 380 486. Secondary growths in pulp-chamber 390 487, 488. Secondary dentin on wall of pulp-chamber, X 100 390 489. Secondary dentin in base of pulp-chamber, X 50 391 490, 491. Pulp-nodules ' 391 492. Section of pulp with pulp-nodule, X 70 392 493. Section of pulp undergoing fibroid degeneration, X HO 392 494-498. Calcification of dental pulp 393, 394 499, 500. Osteodentin 395 501. Bone-tissue in place of resorbed dehtin 396 502-505. Suppuration of dental pulp 408^11 606. Incisor with enlarged pulp-chamber 414 507. Pulpitis, X 300 414 508. Fibrous degeneration of pulp, X 50 415 509. Metallic caps for capping teeth 418 510. 511. Sections showing formation of secondary dentin in coronal portion of pulp- chamber, X 100 422 512. Section of pulp treated with arsenic 425 513. Barbed nerve-broaches 430 514-525. Longitudinal sections of teeth 432 526. Peculiarities in cuspids and bicuspids . . . .' 433 527-534. Sections of bicuspids, showing pulp-chamber and canals 433 535-550. Sections of first, second, and third molars 434 551-557. Abnormalities of dental roots and canals 435 558, 559. Donaldson bristles ; Gates-Glidden drills 435 560. Donaldson pulp-cleansers 435 561, 562. Nerve-extractors 436 563. Pulp-canal pluggers 439 564. Canal probe guage 439 565. Syringe electrode 456 566. Bleaching electrode 457 567. Duplex syringe 457 568. Nipple-expander 458 569. Bleaching electrode in position 458 570. Rubber band causing cementitis 460 571. Dental artery supplying pulp and pericementum , 462 XX LIST OF ILLUSTRATIONS. FIG. PAGE 572. Dunn capillary or drop syringe 463 573. Metal cap to prevent occlusion 464 574. Shreddy sac of tooth abscess 476 575. 576.* Spear-pointed drills ; trephines 484 577. Puncturing alveolar abscess 484 578. Rollin circular knives 498 579. 580. Younger trephines and reamers 499 581. Eollin spiral knives 499 582. Ottolengui combined drill and reamer 499 583. 584. Torsion forceps; bullet forceps 503 585. Gooch's double canula snare 503 586-596. Macroscopic appearances of permanent teeth the roots of which are being resorbed 510 597, 598. Osteoclasts, producing resorption of dental roots 511 599, 600. Transverse sections of roots of teeth, near apex, X 175 514 601-603. Macroscopic appearances of hypercementosed teeth 514 604, 605. Sections of molar roots, hypercementosis, magnified 514 606. Transverse section of molar roots, near apex, X 75 515 607. Transverse section of root of hypercementosed tooth, X 75 515 608. Transverse section of alveolus and apex of root of abscessed molar, X 96 515 609. Inostosis, with formation of a pearl-like globule resembling enamel 515 610. Inostosis, section of root of tooth, X 80 515 611-614. Necrosis of teeth, macroscopic appearances 520 615. Epithelial scales and salivary corpuscles from sordes of mouth, X 50 520 616-619. Salivary calculus 526 620. Glands of Serres, X 50 526 621. Small scalers 518 622. Small rubber disks, wheels, and cups 528 623. Small revolving brushes 528 624. Inflamed peridental membrane from a cage of pyorrhoea alveolaris, X 50 544 625. Removing subgingival salivary deposits 546 626-628. Pyorrhoea alveolaris instruments 547, 548 629. Medicinal drop syringe 548 630-632. Splints for supporting loosened teeth 549 633-636. Gouty pericementitis before and after treatment 563 637. Underlying condition in pyorrhoea alveolaris 564 638. Fibroid degeneration of pulp in pyorrhoea alveolaris, X HO 572 639. Pulp in situ showing calcic degeneration, X 65 572 640. Hyaline degeneration of the pulp, X 100 573 641. Colloid degeneration of the pulp, X 21.25 573 642. Allport's bur 576 643. Improved dento-electric cautery 577 644. Spray apparatus — hand instrument 578 645. Spray apparatus — foot instrument 579 646. Glass tube with capillary point 581 647. 648. Nitrous oxide apparatus 587 649-651. Gas-inhalers 588 652, 653. Hewitt's apparatus for the administration of oxygen with nitrous oxide , 589, 590 654, 655. Mouth-props 592 656. Towel folded as a cone 592 657, 658. Lente's and AUis's inhalers 593 659. Aseptible ether inhaler 594 660. Mouth-mirror 600 661. Gum-lancet 600 662. Curved scissors 600 LIST OF ILLUSTRATIONS. XXl F'IG. PAGE 663-665. Mouth-props and gags 601 666. Laryngeal forceps 601 667. Turnkey 602 668. Aseptic forceps 602 669. Root-elevators 603 670. Dental screw 608 671. 672. Relation of teeth to alveolar processes 604 673, 674. Superior incisor forceps 604 675-678. Inferior incisor forceps 605, 606 679-681. Superior cuspid and bicuspid forceps 606, 607 682-685. Inferior cuspid and bicuspid forceps 607, 608 686, 687. Superior first and second molar forceps 609 688-694. Inferior first and second molar forceps 609-611 695-697. Superior third molar forceps 611, 612 698, 699. Inferior third molar forceps 612, 613 700, 701. Screw-forceps 613 702-705. Superior root forceps 614 706, 707. Inferior root forceps 615 708. Superior alveolar root forceps 615 709. Deciduous inferior universal forceps 616 710. Inferior alveolar root forceps 616 711. Deciduous superior anterior and root forceps 616 712. Deciduous superior molar forceps 616 713. Deciduous inferior anterior and molar forceps 617 714. Deciduous and superior universal root forceps 617 715. 716. Common deformities of teeth 617 717-721. Common malpositions of teeth 617 722. Skiagraph showing misplaced superior cuspid 617 723. Misplaced inferior second and third molars 618 . 724, 725. Forceps for extracting misplaced molars 618 PRINCIPLES AND PRACTICE OPERATIVE DENTISTRY. CHAPTER I. CLASSIFICATION AND DESCEIPTIVE ANATOMY OF THE TEETH. S'eaely all of the mammalia possess a more or less complicated dental system. These organs are applied to various purposes, mainly, however, to that of procuring food by seizing and killing living prey, or gathering and biting off portions of vegetable material, and more indirectly in tearing or cutting through the hard protective coverings of food substances, such as the husks and shells of nuts, or in grinding, crushing, or otherwise mechanically dividing the solid materials before swallowing, so as to prepare them for digestion in the stomach. Fig. 1 shows the peculiar form of the teeth of the mole. In many animals certain teeth are excessively developed, and are used as weapons of offence and defence ; in others the presence or excessive development of certain teeth mark the male sex. Man is an omnivorous animal (the term omnivorous comes from the Latin omnis, all, and voro, I eat), and, as the term imiDlies, eats all kinds of food. He has been endowed by nature with organs of mastication suited to the requirements of cutting, tearing, and grinding these various forms of food. Man's teeth, therefore, represent in jDart those of the carnivora, or flesh-eating animals, and those of the herhivora, or vegetable- eating animals ; in other words, certain of his dental organs are represent- ative of both of these types of animals. The incisors and molars are typical of the herbivora, and are suited to cutting and grinding vegetable fibre and grains, while the cuspids and bicuspids represent the teeth of the carnivora, and are adapted to seizing, tearing, and cutting animal food. NUMBER AND CLASSIFICATION OF THE TEETH. Man, like many others of the mammalia, is endowed with two distinct sets of dental organs, one designed to serve the purposes of the economy during infancy and early childhood, the deciduous, temporary, or milk teeth ; and the other a larger, stronger, and more numerous set, which re- places the deciduous teeth, and is designed to serve the purx^oses of the economy from childhood to old age ; these are designated as the permanent teeth. 1 OPERATIVE DENTISTRY. The deciduous teeth are twenty in number, ten in each jaw, and are expressed by scientists in the following formula : 9 9 11 99 I. - - C. ^^ - ]\I. ^ ^ = 20. 22 11 2 2 The formula is read as follows, beginning at the median line : incisors? two above, two below ; cuspids, one above, one below ; molars, two above, two below, which equals ten on either side of the median line, or twenty in all. Fig. 2. 1 ^ 2 '« 3 M II 4 Deciduous teeth of the left side. (Gray.) 1 and 2, incisors ; 3, euspidati ; 4 and 5, molars. The permanent teeth of man are thirty-two in number, sixteen in each jaw, the formula for which is written thus : I. ?? C. ii B. ~? M. -- = 32. Permanent teeth of the right side. (Gray.) 1, third molars ; 2, second molars ; 3, first molars ; 4, second bicuspidati ; 5, first hicuspidati ; 6, euspidati ; 7, lateral incisors ; 8, central incisor;. Beginning at the median line, it reads as follows : incisors, two above, two below ; cuspids, one above, one below ; bicuspids, two above, two y )V: ":\^^i^M?^ Fig. 1. — Vertical section of inferior maxilla and teeth in silu of mole. X 15. Fig. 4.— Showing structures of a tooth. 1, enamel ; 2, cementum ; 3, dentin ; 4, pulp- chamher. Fig. 5. — Occlusion of the teeth. (After Cryer.) Root Apex Cervix Crown Cutting edge Fig. 6. — Superior left central incisor, labial surface. (Enlarged.) Fig. 7. — Superior right central incisor, labial surface, showing short root. ( Enlarged. ) CLASSIFICATION AND DESCRIPTIVE ANATOMY OF THE TEETH. 3 below ; molars, three above, three below, equals sixteen on either side of the median line, or thirty-two in all. The ten anterior permanent teeth of each jaw are sometimes called the teeth of replacement, or succedaneous teeth, from the fact that they replace the deciduous teeth. The permanent incisors and cuspids take the x)lace of the temporary teeth of the same name, while the bicuspids assume the positions occupied by the temporary molars. The permanent molars appear one by one behind the position occupied by the second deciduous molars. DESCRIPTIVE ANATOMY OF THE TEETH. The teeth are specialized organs of mastication implanted within the alveolar processes of the superior and inferior maxillse in man and in many animals. The teeth are composed of five tissues (Fig. 4) : a vitreous-like substance which completely covers the crown — the enamel (1) ; a bone-like substance which envelops the root — the cementum (2) ; and a hard substance, less dense than enamel but harder than bone, which forms the interior or body of the organ — the dentin (3) ; while a small mass of soft tissue occu- pies a central cavity (4) within the crown and the root — the pulj) ; and a fibrous membrane covers the cementum of the root — the pericementum. In a normally developed individual of the genus homo the teeth are arranged in the form of two parabolic or elliptical curves, the su^oerior arch describing a trifle larger curve than the inferior, so that the teeth of the former slightly overreach their antagonists in the latter. The buccal cusps of the ux^iDer bicuspids and molars close over the buccal cusps of the lower teeth ; this brings the buccal cusps of the lower teeth within the sulci of the upper, and the palatal cusj)S of the upper teeth within the sulci of the lower. The incisors, cuspids, and bicuspids of the lower jaw are smaller than the corresponding teeth in the upper, the greatest differ- ence being in the size of the incisors. The superior incisors and cuspids are slightly longer than the inferior and overlaj) them, while the cuspids and molars not only overreach their opposites in the inferior maxilla, but so interlock at their occlusal surfaces that each tooth, except the third sux^erior molars, occludes or antagonizes with two of its fellows in the opposite jaw, when the teeth are brought into their normal occlusion. (Fig. 5. ) This arrangement permits the whole of the occlusal surfaces of these teeth to be brought into contact by the various movements of the jaws in mastication, thus rendering the function of triturating the food and pre- paring it for digestion most effective. A normal incisor tooth presents certain characteristics which are com- mon to all the dental organs of man ; it will therefore serve the purpose of illustrating the anatomical divisions of the teeth, which are as follows : the crown, the cervix, the root, the pidp-chaml>er, the pulp-canal, the morsal-'<^ or cutting edge, the apex, and the apical foramen. A more minute description relative to the cusps, surfaces, angles, margins, grooves, fissures, etc., will be reserved for the special anatomy of the individual teeth. * The term morsal is used, following the suggestion of Dr. Thompson, in the- place of incisive or cutting edge and occlusal surface. 4 OPERATIVE DENTISTRY. The crown is tliat portion of the tooth which is visible within the mouth, projecting beyond the gum ; the cervix or necJc is that part repre- sented by a constriction between the crown and the root at the point where the enamel and the cementum meet, or, in other words, the portion grasped by the margin of the gum ; the root is that part which is implanted within the alveolar process of the jaw and covered by the gum ; the morsal edge or cutting edge is that portion of the crown which occludes or antagonizes with a tooth in the opposite jaw ; the apex is the terminal end of the root, that portion farthest removed from the crown (Fig. 6 ) ; the pulp -chamber is a cavity or cul-de-sac located within the crown, and may be termed a coronal enlargement of the pulp-canal which extends through the centre of the root from its apex to the pulp-chamber within the crown ; the apical foramen is the orifice or entrance to the pulp-canal located in the apex of the root. ARCHITECTURAL DESIGN OF THE TEETH. It is important to the dental student that he understand and appreciate the architectural design upon which nature has constructed the dental organs. The more closely he studies this design, in both their gross and minute anatomy, the more will he become impressed with the x)erfection of the general plan and the admirable adaptation of their form, their structure, and their tissues to perform the functions for which they were created. The form of the teeth is designed upon the plan of the cone, modified to meet the individual requirements of the several classes of teeth ; some are comxDosed of a simj^le cone, like the incisors and cusi3ids, while others are a combination of two or more cones, as in the bicuspids and molars. In no way can these facts be taught so well as by modelling in clay the forms of the various classes of teeth, commencing with the sim^^le forms as expressed in the single-rooted teeth, and progressing to the more com- plex through a series of double and multiple cones in the formation of the bicuspids and molars. THE INCISORS. There are eight incisor teeth in the dental series of man, four in the upper jaw and four in the lower, two situated upon either side of the median line of the jaw ; the first are termed the central incisors, and those next in order upon the distal side of the centrals are known as the lateral incisors. The situation of the central incisors in the extreme anterior portion of the jaw upon opposite sides of the median line causes their mesial sur- faces to approximate each other. The function of the incisor tooth is to cut or incise the food, — ^hence its name, which is derived from the Latin, incido, to cut. These teeth are all designed upon the form of the truncated cone, with slight modifications, to meet the requirements of the individual organ. The Superior Central Incisor. — This tooth is in form a modified truncated cone with its base flattened out to form the morsal or cutting edge. It presents for examination four surfaces, — labial, lingual, mesial, and CLASSIFICATION AND DESCRIPTIVE ANATOMY OF THE TEETH. 5 distal^- two angles, — mesial and distal; and a morsal edge. The general fornf of the crown is that of the wedge or chisel, the edge being quite thin, the angles rounded, and the thickness rapidly increasing to the cer- vix of the tooth. It is also slightly curved from the cervix to the morsal edge, and curved over mesio-distally, so that the labial surface is somewhat convex and the palatal concave. The labial surface (Fig. 7) of the crown is in general outline an imper- fect quadrilateral, the cervical margin being rounded. This surface has four margins, — mesial, distal, cervical, and morsal or incisive. (Fig. 8.) The mesial margin begins at the morsal margin or cutting edge, and extending upward, usually with a slight distal inclination, unites with the cervical margin. The distal margin also begins at the morsal mar- gin, and extends uj)ward with a slight mesial inclination, uniting with the cervical margin. Both of these margins are more or less convex. The cervical margin is somewhat rounded, the form following the outline of the gingival border, where it unites with the mesial and distal mar- gins. The morsal margin extends from the mesial margin to the distal margin. The union of the mesial and morsal margins form the mesial angle, while the union of the distal and morsal margins form the distal angle. The mesial angle is usually pointed and square, while the distal is much more obtuse. Two shallow grooves or depressions— the lahial grooves — traverse the labial surface in a longitudinal direction, dividing it into three lobes, the mesial, median, and distal. These grooves extend from the morsal edge to the middle or upper third of the labial surface, where they broaden out and disappear. They are termed developmental lines (Black), and represent the three x)rimitive j^lates of calcification in the develop- ment of the tooth, the grooves being formed by the union of these plates with each other. Occasionally one or more transverse ridges are found upon the cervical portion. The lingual surface (Fig. 9) of the crown is triangular in outline, smaller than the labial surface, and presenting a more or less angular concavity, the lingual fossa. This fossa is bounded by three marginal ridges and the morsal or cutting edge. The mesio-marginal ridge extends from the mesial angle upward to the cervico-marginal ridge, following the curvature of the mesial margin. The disto -marginal ridge extends from the distal angle to the cervico- marginal ridge, following the curvature of the distal surface. The cervico-marginal ridge forms a curved line at the cervix or base of the crown, uniting by its extremities with the mesial and distal marginal ridges. The marginal ridges are often high and conspicuous, and the cervico-marginal ridge is sometimes develo^Ded into a cusp, the ridge at the base forming a girdle or cingulum. The lingual fossa is usually smooth, but occasionally it forms a deep depression or pit, while a fissure may extend from it into the cervico-marginal ridge. Two longitudinal grooves are sometimes seen traversing the lingual fossa, which correspond to the developmental grooves upon the labial surface. The Mesial and Distal Surfaces. — The outlines of these surfaces (Figs, 6 OPERATIVE DENTISTRY. 10 and 11) are irregular triangles, with tlie base directed towards the root and the apex terminating at the incisive or morsal edge. The base of the triangle is concaved at the cervical margin, and the apex rounded or con- vex at the morsal edge. These surfaces have three margins, — labial, lingual, and cervical. The mesial surface is slightly longer than the distal surface, and presents a more or less convex and rounded form, slightly flattened near the cervical margin. The distal surface is rounded as in the mesial, but more curved in its longitudinal axis. The labial margins of these surfaces are convex, following the outline of the labial surface, while the lingual and cervical margins present concave outlines, following the curves of the lingual surface, and the cervical line. The incisive edge or morsal vnargin of the crown is formed by union of the labial and lingual surfaces, and extends in a nearly straight line from the mesial to the distal surface, with a slight downward j)itch towards the median line. In a recently erupted tooth this line is often broken by the presence of the developmental grooves ; these, however, soon disappear with use, leaving the line comparatively straight. In a normal occlusion these teeth shut over the lower incisors, but occasion- ally they will be found to occlude squarely with their fellows of the lower jaw. The cervix or cervical line or margin is clearly and distinctly marked by the free extremity of the enamel which covers the crown of the teeth. The termination of the enamel at the neck of the tooth marks the extent of the peridental membrane. The enamel edge, which slopes off more or less abruptly to meet the cementum, does not form a straight line around the tooth, but curves upward upon the root at the labial and lingual surfaces and downward at the mesial and distal surfaces, thus forming in outline a double convexity and a double concavity. The root in section of the tooth at the cervix shows it to be broader on the labial than the lingual surface, — i)ear-shaped, — and this condition is maintained throughout the greater length of the root. In general outline the root has the form of a slender cone. The aver- age length of the superior central incisor is 0.88 inch (2.23 centimetres), of the crown 0.39 inch (0.99 centimetre), and of the root 0.49 inch (1.24 centimetres).* The pulp-chamber is large, and the pulp-canal usually gives free access to the aioex. In young teeth the cornua extend well towards the angles, while in old x>ersons the pulp-chamber and canal is often constricted, making it difficult of access. The Superior Lateral Incisor. — This tooth is the second in the dental arch from the median line, and approximates the central incisor upon its distal surface. It is a little shorter, and about a third narrower than the central incisor, has the same general form and architectural design, and is possessed of the same developmental grooves. * AU measurements of the teeth are taken from Black's Dental Anatomy. Mesial angle Morsal edge Labial grooves Fig. 8. — Superior left central incisor, labial surface. (Enlarged.) Cervical margin Cervico- marginal ridge Distal margin Distal angle Disto- marginal ridge Lingual fossa Fig. 9. — Superior left central incisor, lingual surface. (Enlarged.) Pig. 10.- -Superior left central incisor, mesial surface. (Enlarged.) Fig. 11. — Sviperior left central incisor, distal surface. (Enlarged.) Labial grooves Fig. 12. — Superior right lateral incisor, labial surface. (Enlarged.) Morsal edge Fig. l.S. — Superior right lateral incisor, lingual surface. (Enlarged.) Fig. 15. — Superior right lateral incisor, mesial surface. Fig. 16.— Superior right lateral incisor, distal surface. (Enlarged.) (Enlarged.) CLASSIFICATION AND DESCRIPTIVE ANATOMY OF THE TEETH. 7 The crown presents for examination four surfaces, labial^ Ungual, mesial, and distal ^- a cervical margin, an incisive or morsal edge, a mesial and a distal angle. The labial surface of the crown (Fig. 12) is more rounded than in the central, the mesial angle is acute, and the morsal edge sloi)es upward to a rounded and obtuse distal angle. The mesial half of the crown seems to partake of the form of the central incisor, while the distal half approaches the form of the cuspid. In the young tooth the morsal edge, as in the cen- tral, presents three tubercles, more or less distinct, with the developmental grooves passing between them. The lingual surface (Fig. 13) in a majority of instances is the broadest part of the crown. It is less concave than in the central, but more de- pressed at the base of the cervical ridge. The mesial and distal marginal ridges are in proportion to the size of the tooth, broader and stronger than in the centrals. The cervical ridge is also well marked and propor- tionately broader and stronger than in the central. Occasionally, however, the marginal ridges are but slightly developed ; the surface is then quite smooth. The lingual fossa may be divided by a longitudinal ridge with slight depressions upon either side between it and the marginal ridges. The cervical ridge is sometimes very prominent, forming a cingulum, at the centre of which a tubercle is often developed. An exaggerated development of this cusp or cingule is shown in Fig. 14, a, from a case reported by W. H. ^*^ Mitchell. As a consequence of this greater prominence of the cingulum, and the marked depression or pit so often found at its base, caries is more liable to occur upon the lingual surfaces of the superior laterals than upon those of the central incisors. The mesial and distal surfaces (Figs. 15 and 16) present a triangular or Y-shaped outline similar to that of the central incisor. The mesial surface is rounded near the morsal edge, but considerably flattened near the cervix. A slight depression sometimes exists at this point, while the mesio-labial angle occasionally presents a flattened or depressed jDoinfc midway between the morsal edge and the cervix. The distal surface is convex in all directions, and quite full at the morsal or incisive third 5 from this point it slopes towards the cervical line, where it becomes quite flat. The morsal edge is divided into two parts by a more or less prominent tubercle. The mesial half is straight, like that of the central, while the distal half has a slight upward slope, terminating in a rounded distal angle. When the tubercle becomes worn off, the edge is straight, with a pitch towards the median line. The cervix is considerably flattened mesio-distally. Section of the root at this point shows the form to be a flattened oval. The cervical line follows the same course as in the central incisor, having an upward curve upon the labial and lingual surfaces, and a downward curve ujDon the mesial and distal surfaces. 8 OPERATIVE DENTISTRY. The enamel margin does not, as a rule, end so abruptly as in tlie central incisors, although occasionally it will end in a sharply defined ridge. The root of the tooth is conical, but more or less flattened mesio- distally ; its labio-lingual diameter at the neck is about one-third greater than its mesio-distal diameter. The root is generally straight, but in many specimens the apex has a slight distal curvature. Occasionally it is very crooked. The average length of the superior lateral incisor is 0.85 inch (2.15 centimetres), of the crown 0.34 inch (0,86 centimetre), and of the root 0.51 inch (1.29 centimetres). Tlie lateral incisors are the most variable in size and form of all the dental series of man, and they more frequently fail to appear in the dental arch — suppressed— than any others except the third molars. They are often imperfectly developed, and not infrequently present a conical or peg- shaped form. In one instance which has come under the observation of the writer, the superior lateral incisors have been absent in certain mem- bers of a family for three generations. The father had never erupted these teeth, his only daughter had the same deformity, and of her four children, two boys and two girls, the eldest son and both daughters have never erupted them, while these teeth in the second son are developed and peg-shaped. The pulp-canal partakes of the shape of the root, which is generally flattened, and when the root is straight it can be readily entered and fol- lowed to the apex 5 but in operating for the removal of the pulp, the possibility of encountering a root with a curved apical end must not be overlooked. THE LOWER INCISORS. The lower incisors have the general outlines of the superior laterals, but they are in every way smaller, the roots are much more flattened mesio- distally, and often have a groove upon the mesial and distal surfaces run- ning from the cervix to the apex. The labio-lingual diameter of the root is much greater than its mesio- distal diameter. They are located in the anterior portion of the lower jaw upon either side of the median line, opposite the superior incisors, with which they occlude in cutting food. The developmental lines are the same, but the tubercles upon the morsal edge and the labial grooves are less strongly marked than in the superior incisors. The lower central incisor is the smallest tooth of the dental series of man. It is chisel-shaped in form. The crown, viewed mesio-distally and labio-lingually, is composed of a double wedge. The widest portion of the crown is the morsal edge, which is thin and straight. From this point it slopes slightly to the cervix, where it is only about one-half as wide as at the edge. The labial surface (Fig. 17) has the outline of a slender wedge, its widest portion at the morsal edge, and its narrowest at the cervix. It is nearly straight, or only slightly convex near the edge, but as it approaches the cervix it becomes more rounded and convex. The cervical margin is well defined and concave towards the root. The mesio-labial and disto-labial Ijrtbial groOA't'S Mesial angle Mesio- marginal ridge Cervical ridge Cervical line Fig. 17. — Inferior right central incisor, labial surface. Fig. 18. — Inferior right central incisor, lingual surface. ( En larged . ) ( Enlarged . ) Fig. 19.— Inferior right central incisor, mesial surface. Fig. 20.— Inferior right central incisor, distal surface. (Enlarged.) _ (Enlarged.) Fig. 21. — Inferior right lateral incisor, labial surface. Fig. 22. — Inferior right lateral incisor, lingual surface. (Enlarged.) (Enlarged.) Fig. 23. — Inferior right lateral incisor, mesial surface. Fig. 24. — Inferior right lateral incisor, distal surface. (Enlarged.) (Enlarged.) CLASSIFICATION AND DESCRIPTIVE ANATOMY OF THE TEETH. 9 margins are rounded off at tlie expense of tlie labial surface. The mesial angle is quite acute, and tlie distal angle slightly obtuse and rounded. The lingual surface (Fig. 18) is concave from the mesial edge to the cervix, but is nearly flat, or only slightly concave mesio-distally. The marginal ridges are not strongly marked. The mesial and distal surfaces (Figs. 19 and 20) are Y-shaped in outline, with the apex directed towards the morsal edge of the crown. They are convex near the edge, but become flattened and even slightly concave at the cervix. The cervix is flattened mesio-distally, the greatest diameter being the labio-lingual. Section at this i)oint gives the form of a comi^ressed oval. The root is flattened like the cervix, for its entire length. The apex sometimes has a distal curve. The groove upon the mesial and distal surfaces is sometimes quite deep and occasionally results in bifurcation. ThQ ])ulp canal is thin and flattened, partaking of the form of the root ; in some instances it is with great difficulty that the canal can be entered with the most delicate instruments. The average length of the inferior central incisor is 0.81 inch (2.05 centimetres), of the crown 0.34 inch (0.86 centimetre), and of the root 0.47 inch (1.19 centimetres). The inferior lateral incisor (Figs. 21, 22, 23, and 24) is similar in form to the inferior central, but, unlike the superior incisors, it is distinctly larger than the centrals, not only in width of crown, but also in the length of the root, while the marginal ridges are more strongly marked and the fossa more distinct. The morsal edge has a slight distal pitch, and the distal angle is obtuse and rounded. The average length of the inferior lateral incisors is 0.85 inch (2.15 centi- metres), of the crown 0.35 inch (0.88 centimetre), and of the root 0.50 inch (1.26 centimetres). THE CUSPIDS. There are four cuspids in the dental series of man, two in each jaw. They are situated just in front of the angle of the mouth, between the lateral incisor and the first bicuspid tooth ; they are the third in order from the median line, and form the spring of the superior dental arch. These teeth are variously known as cuspids, cuspidati, canines, and eye- teeth. The term cuspid comes from the Latin cuspis, a i3oint. The cuspid teeth are in all respects larger and stronger than the incisors, the crown is thick and spear-pointed, and the root long and heavy. The architectural form of these teeth adapts them for seizing, piercing, and tearing animal food, and they represent the carnivorous element in man. The Superior Cuspids. — The crowns of the superior cusiDids present for examination four surfaces, the labial, lingual, mesial, and distal, two margins, the cervical and morsal, and two angles, the mesial and the distal. The general outline of the crown is that of a short cone with its base at the gum line, and it represents the primitive conical teeth of many of the fishes. 10 OPERATIVE DENTISTRY. The lahial surface (Fig. 25) of tlie crown in outline is spear-shaped. It is convex in all directions, and is much more rounded mesio-distally than the incisors. The developmental grooves and ridges are often quite promi- nent. The distal groove is usually most strongly marked, which brings the central and distal lobes into greater prominence. This surface is bounded by five margins, the mesial, distal, cervical, mesio-morsal, and disto-morsal. The mesial and distal margins are rounded and convex from the morsal edge to the cervical margin ; the convexity being greatest in the distal margin. The distal margin is slightly shorter than the mesial on account of the sharper slope of the disto-morsal edge. The cervical margin follows the contour of the gum* line, and unites with the mesial and distal margins. The morsal margin is divided by a prominent cusp, from the summit of which gi-adually slope away the mesio-morsal and disto-morsal margins. The mesio-morsal margin slopes slightly ui)ward, and is usually a trifle concave, though occasionally it is convex. The disto-7norsal margin may be described in the same manner, except that it is a little longer, and has a slightly more i)ronounced upward slope and a deeper concavity. The widest part of the labial surface is at a line drawn from the mesial to the distal angles ; the narrowest part is at the cervical margin. The lingual surface (Fig. 26) presents nearly the same general outline of the labial surface, with the exceptions that it is more flat, sometimes concave, and has three generally well-defined marginal ridges. The mesio-marginal and disto-marginal ridges arise at the mesial and distal angles, and pass upward, where they unite with the cervico-marginal ridge, which may be said to be formed by the union or continuation of the two former ridges. The cervico-marginal ridge is sometimes quite prominent, terminating in a more or less pronounced tubercle or cusj). Between the mesio- and disto- marginal ridges there is a prominence known as the lingual or triangular ridge, upon either side of which are sometimes deep fossa or fissures, but more frequently they are shallow and ill-defined. The mesial surface (Fig. 27) resembles that of the central incisor in many respects. It is convex in all directions at the mesial angle, but as it ap- proaches the cervix it becomes flattened and occasionally concave. The distal surface (Fig. 28) in general outline is similar to the mesial surface, except that it is more rounded, and, as it nears the cervix, not quite so flat. The distance from the cervix to the distal angle is nearly one-third shorter than the distance on the mesial surface from the cervix to the mesial angle. The morsal edge by its form gives to the cuspid tooth a double function, that of incising and penetrating. The morsal edge combines a cusp which is placed near the centre, to the long axis of the tooth, and two cutting or incisive edges which slope away from it in an upward direction, and termi- nate at the mesial and distal angles. The distal edge is longer than the mesial, and it has a more acute upward slope. The sharp cusp is soon worn off, and in old age the morsal edge may be reduced to a straight line. Apex Disto- morsal margin Morsal margin Pig. 25.— Superior right cuspid, labial surface. (Enlarged.) Cervical margin Cervical line Mesial angle Mesio- morsal Mesial angle margin Fig. 26.- -Superior right cuspid, lingual surface. (Enlarged.) Fig. 27.— Superior right cuspid, mesial surface. (Enlarged.) Fig. 28.— Superior right cuspid, distal surface. (Enlarged.) Distc- inoi'Sii 1 Distill aiiKli3 Cervical inargiii ^0^H M Mcsin- inorsal edge Mesial Labial lidge Cervical ridge -Inferior right cuspid, labial surface. (Enlarged.) ]^iG. .30.— Inferior right cuspid, lingual surface. (Enlarged.) Fig. 31. — Inferior right cuspid, mesial surface. (Enlarged.) Fig. 2. — Inferior right cuspid, distal surface. (P^nlarged.) CLASSIFICATION AND DESCRIPTIVE ANATOMY OF THE TEETH. 11 The cervix on section presents a flattened oval. The enamel line maintains about the same outline as in the central incisors, curving upward upon the labial and lingual surfaces, and downward upon the mesial and distal. Occasionally it presents a slight dei)ression both mesially and distally, which may be continued upon the root as a groove. The root is the longest of all the human teeth, and is irregularly coni- cal in form, tapering to a slender point ; it is usually straight, but may be curved or very crooked. In size it is about one-third larger than the central incisor. It is flattened slightly mesio-distally, and occasionally grooved. The pulp-canal is large and accessible, usually of the same form as the root, and except when the root is curved or crooked, can be easily followed to its apex. The average length of the superior cuspid is 1.05 inches (2.66 centi- metres), the average length of the crown is 0.37 inch (0.94 centimetre), and of the root 0.68 inch (1.72 centimetres). The Inferior Cuspids. — There is probably a greater similarity be- tween the superior and inferior cuspids than between any other class of teeth in the human mouth. They are alike in form and outline, though the inferior are somewhat smaller. The crowns are a little longer, and this makes them appear more slender ; they are also more flattened mesio-dis- tally at the cervix and in the root. These teeth are heavily built and firmly set in their alveoli, in order to enable them to perform the double function of incising and tearing food. The cusp is generally more promi- nent and pointed than in the superior cuspids. The crown opposes the mesial surface of the superior cuspid and the distal surface of the superior lateral incisor. The labial surface (Fig. 29) of the crown is smooth and convex, the de- velopmental grooves are less prominent than in the superior cuspids ; the labial ridge, however, is well developed, and extends from the cusp to the cervical margin, giving additional strength to the crown. Transverse ridges are also occasionally present in the cervical region. To accommo- date the occlusion of the superior teeth, the labial surface of the crown is inclined inward. The lingual surface (Fig. 30) is quite smooth, the ridges and grooves being less strongly marked than in the superior cuspids. The lingual ridge, which extends from the cusp to the cervical ridge, is, however, sometimes quite prominent. In exceptional cases the cervical ridge is strongly developed, forming a fossa at its base. The mesial surface (Fig. 31) is rounded at the eminence, flattened at the cervical third, and nearly straight with the surface of the root, which gives the crown the appearance of being bent backward or having a distal in- clination. The distal surface (Fig. 32) is quite convex and the disto-morsal angle prominent ; as it approaches the cervix it becomes more or less flattened, and at the cervical margin may present a slight concavity. The morsal edge presents a more or less prominent cusp and a mesial and a distal incisive edge. The distal edge is longer than the mesial, and 12 OPERATIVE DENTISTRY. slopes away rapidly to the distal angle. Tlie differences, however, are not so marked as in the superior cuspids. The angles are pronounced, but the mesial less so than the distal. The cervix is generally found on section to be oval in form, although sometimes it is flattened mesio-distally, and when the root is grooved it may present a modified hour-glass outline. The curves of the enamel line are not so variable as in the incisors, nor the termination of the enamel quite so abrupt as in the superior cuspids. The root is long, straight, tapering, and flattened mesio-distally. It is shorter than the superior cuspid, and not infrequently presents a decided depression or groove upon its mesial and distal surfaces, showing a ten- dency towards bifurcation. The apex is slender and sometimes curved in a labial direction. The piilp-canal has the same general outline as the root, and when the longitudinal grooves upon the mesial and distal surfaces are deep, the canal is constricted in the middle, making it more or less difficult to enter with instruments. The average length of the inferior cuspids is one inch (2.53 centimetres), of the crown 0.40 inch (1.01 centimetres), and the root 0.60 inch (1.52 centimetres.) THE BICUSPIDS. The bicuspids, or premolars, as they are sometimes termed, are the fourth and fifth teeth from the median line, and are situated between the cuspid and first molar teeth. There are eight bicuspids in a normal denture of man, two upon each side in the upper and lower jaws. The one which is situated next to the cuspid tooth is termed the Jirst Mcuspid, and the one located between the first bicuspid and the first molar is known as the second Mcuspid. The term Mcuspid is derived from the Latin M, two, and cuspis, a point, — two-pointed or bi-cusped ; a tooth, therefore, with two cusps. Architecturally the bicuspid tooth is formed of two cones fused together. This structure, from the mechanical stand-point, is weak and faulty, as its power of resistance to the mechanical force applied in mastication depends upon the strength of the mesial and distal marginal ridges which bind the cones together upon the morsal surface ; when these for any reason have been destroyed, the greatest weakness of the structure is developed, ending in the separation of the cones under stress and the loss of one or both cusps. Fractures of this character occur more frequently in the bicuspids on account of their mechanical weakness than in any of the other teeth. The bicuspids succeed and replace the deciduous molars, and by reason of their smaller size give extra space in the jaws for the permanent cuspids, which are much larger than their deciduous predecessors, and are, as a rule, erupted at a later period. The function of the bicuspids is to divide the food into small pieces and prepare it to be triturated by the molars. The superior first bicuspids, viewed from the morsal surface, have the form of a rounded quadrilateral, the buccal margin being broader than the linguaL Section through the crown just beyond the cusi)s shows a somewhat pear-shaped outline. The design of this form is to make it pos- Mesin- niorsal edge Fig. 83. — Superior right first bicuspid, buccal surface. (Enlarged.) Lingual cusp Fig. 34. — Superior right first bicuspid, lingual surface. (Enlarged.) Lingual cusp Fig. 35.— Superior right first bicuspid, mesial surface. (Enlarged.) Buccal cusp Fig. 36. — Superior liglit first bicuspid, distal surface. (Enlarged.) Buccal triangular ridf^e Lingual cusp Fig. 37.— Superior right first bicuspid, morsal surface. (Enlarged.) Fig. 38. — Superior right second bicuspid, buccal surface. (Enlarged.) Lingual cusp Fig. 39. — Superior right second bicuspid, lingual surface. (Enlarged.) Fig. 40. — Superior right second bicuspid, mesial surface. (Enlarged.) CLASSIFICATION AND DESCRIPTIVE ANATOMY OF THE TEETH. 13 sible for these teetli to follow the curve of the alveolar arch. The bucco- liugnal diameter of the crowu is about one-third greater thau its mesio- distal diameter. The 'buccal surface (Fig. 33) of the crown is almost a counterpart of the corresponding surface of the superior cuspid, with the excei^tion that the cusp is placed nearer the centre of the crown, thus making the mesial and distal morsal margins nearly of the same length. The central or buccal ridge which springs from the cusp is prominent, while the mesial and distal ridges or lobes are rarely conspicuous. The developmental grooves or furrows between them are, therefore, shallow and extend only about half-way to the cervix, where they are lost in the smooth convexity of the cervical half of this surface. The surface is considerably narrower at the cervical margin, which gives it the general outline of a cone, with the apex at the cervical margin. This difference in the width of the buccal surface at the angles and at the cervix gives the "^bell-shaped" form to these teeth. The lingual surface (Fig. 34) is mesio-distally regularly convex. From the lingual cusp to the cervix it presents a nearly straight line, though many times it is slightly convex, and occasionally fully as much so as the buccal surface. Mesio-distally the surface is not so broad as the buccal surface, and the lingual cusp is not quite so long. The mesial surface (Fig. 35) bucco-lingually is much flattened, but slightly convex ; from the mesio-morsal marginal ridge to the cervix it is also slightly convex, although examples are numerous in which a shallow concavity is presented at the cervical margin, which extends to the side of the root in a more or less sharj^ly defined groove. The marginal angles formed by the union of this surface with the buccal and morsal surfaces are well defined, but the mesial and lingual surfaces are so blended and rounded that it is difficult to designate their line of union as an angle. The distal surface (Fig. 36) is so nearly like the mesial surface that it needs no especial description except in the points of difference. It is rather more convex than the mesial surface, has rarely a convexity at the cervical margin, and the disto-morsal angle is more prominent than the mesio-morsal. The morsal or occlusal surface (Fig. 37) presents an abrupt change in form and function as compared with the morsal edge of the cuspid tooth. This surface is composed of two well-defined cusps or points divided by a deep sulcus having a mesio-distal direction, and bound together at their bases mesially and distally by two strong and prominent ridges termed the mesio-morsal and the disto-morsal ridges. One of these cusps is situated at the buccal margin, and the other at the lingual, and from their situation are designated as the buccal and the lingual cusps. The buccal cusp is usually sharper, longer, and more prominent than the lingual cusp. The lingual cusp is broader and more rounded. From the summit of the buccal cusp four ridges slope away at right angles, one mesially to form the mesio-morsal edge of the crown ; one distally to form the disto-morsal edge ; one to the buccal surface, forming the central buccal ridge, and another slopes downward in an opposite direction to form 14 OPERATIVE DENTISTRY. the huccal triangular ridge, whicli ends either in the central sulcus or joins a similar ridge descending from the summit of the lingual cusp, and forms the transverse ridge. The mesio-morsal aud disto-morsal edges enter into the formation of the mesial and distal morsal angles at their extremities. The lingual cusp is usually blunt, and its margins, which are not sharply defined, unite with the marginal ridges at both angles. The lingual trian- gular ridge arises at the summit of the lingual cusp, and either terminates at the central sulcus or joins its fellow of the buccal cusp to form the trans- verse ridge. The lingual triangular ridge is seldom prominent, and some- times is entirely absent. The central sulcus extends from one lateral ridge to the other in a mesio- distal direction, and widens into the mesial and distal sulci at each end. The mesial and distal sulci are not always well defined, and are seen passing over the central portion of the mesial and distal marginal ridges. The mesial and distal triangular grooves are situated at the base of the marginal ridges, and are directed towards the mesial and distal angles, dividing the marginal ridges from the triangular, where they are either lost or may be traced as slight depressions near the angles. These sulci often become the seat of caries. The cervix is flattened laterally, its bucco-lingual diameter being some- what greater than its mesio-distal. The enamel line curves slightly upward at the buccal and lingual cervical margins, and dips downward a very little, or may describe a nearly straight line at the mesial and distal cervical margin. The root is considerably flattened laterally, and is generally more or less deeply grooved from the cervix to the apex, and often bifurcated for from one-third to two-thirds of its length. The root over the buccal cusp is the buccal root, and that over the lingual cusp is termed the lingual root. Bifurcated roots in the first superior bicuspid is the rule in the negro and other races of a low order of intelligeiice, and also in the apes. It is often very crooked, or may be triple-rooted. The pulp-canal usually takes the form of the root, and may be either single or double. It is narrow at the neck, and often constricted in the middle, giving it the outline of an hour-glass. More often, however, it has two distinct pulp-canals. The coronal portion of the canal terminates in two well-defined cornua or horns which point towards the cusps of the crown. The average length of the first bicuspid is 0.80 inch (2.03 centimetres), of the crown 0.32 inch (0.81 centimetre), and of the root 0.48 inch (1.21 centimetres). Tlie superior second bicuspid so nearly resembles the first that its diflerences only need to be noticed. It is in every way a little smaller ; the cusps are reduced, while the lingual cusp equals or exceeds the buccal cusp in size and length. The marginal ridges are broader, and the morsal surface more flattened, and often presents several shallow wrinkles or supplemental grooves and ridges, which radiate from the central sulcus. The triangular ridges are often united, thus increasing the strength of the tooth. The crown is narrower mesio-distally, and the cervix more oval, Buccal cvisp Fig. 41. -Superior right second bicuspid, distal surface. (Enlarged.) Lingual cusp Fig. 42. — Superior right second bicuspid, morsal surface. (Enlarged.) Buccal ridge Transverse ridge Fig. 43. — Inferior right first bicuspid, buccal surface, (Enlarged.) Fig. 44.— Inferior right first bicuspid lingual surface. (Enlarged.) Triangular or transverse ridge Buccal cusp Fig. 45. — Inferior right first bicuspid, mesial surface. Fig. 46. — Inferior right first bicuspid, distal surface. (Enlarged.) (Enlarged.) Buccal cusp Buccal cusp Buccal ridge Mesial Central Disto- morsal ridge Disto- margi ridge Distal Mcsio- maiginal ridge Lingual rid.tre or cusp Fig. 47. — Inferior right first bicuspid, morsal surface. (Enlarged.) Me>io- liiigual cusp Lingual groove Fig. 48. — Inferior right second bicuspid, morsal surface. (Enlarged.) CLASSIFICATION AND DESCRIPTIVE ANATOMY OF THE TEETH. 15 while the cervico-marginal line curves slightly downward upon the mesial surface only. The greatest difference between these teeth is in the root, which is a little longer than the first ; very rarely bifurcated ; is much flattened from the cervix to the apex, and often deeply grooved upon the mesial surface at the apical third, (See Figs. 38, 39, 40, 41, and 42.) Occasionally the root is rounded and conical. Crooked roots are of more frequent occurrence than in the other bicuspid, and it has a tendency to be rotated in its alveolus, more frequently in a distal than in a mesial direction. The pulp-canal is usually single, and gives free access to its apex. The average length of the tooth is 0.84 inch (2.13 centimetres). The average length of the crown is 0.29 inch (0.73 centimetre), and of the root 0.55 inch (1.39 centimetres). THE INFEEIOE BICUSPIDS. These teeth occupy the same relative positions in the lower jaw that the superior bicuspids occupy in the upper jaw. They are the smallest of the bicuspid teeth, and are distinctive in form, particularly in their morsal surface. The transition in form from bicuspids to molars is more marked in the lowers than in the uppers. In the inferior first bicuspid the lingual cusp is rudimentary, and in the second it is large and broad, and divided bucco-lingually through the centre by a more or less deep furrow, giving it the appearance of a tri- cuspid tooth. In architectural form, these teeth are constructed from a single cone, the peculiarities of the crown being the result of various additions or cingules to the primitive cusp. Unlike the superior bicuspids, the buccal and lingual cusps are connected by a transverse ridge. The Inferior First Bicuspid. — This tooth is the smallest of all the bicuspids, and more nearly resembles a cuspid than a bicuspid, on account of the imperfect development or suppression of its lingual cusp, which is often little more than a cingule. In general outline the crown is much more rounded than the superior bicuspids, and its bucco-lingual and mesio-distal measurements are nearly equal. The buccal surface (Fig. 43) viewed from the buccal aspect, looks like a cuspid. In form the buccal surface is a long oval, surmounted by an acute point. It is convex in all directions. The buccal cusp is situated a little to the distal of the centre of the crown, while the curvature of the buccal surface towards the lingual side places the buccal cusp nearly in a central position to the long axis of the tooth. The lingual surface (Fig. 44) is convex mesio-distally, and nearly straight from cervix to morsal margin. The tooth is slightly bent at the cervix in a lingual direction, which gives the crown a lingual inclination. The length of this surface depends upon the length of the lingual cusp or cingule ; usually it is only about half as long as the buccal surface. The mesial and distal surfaces (Figs. 45 and 46) are convex bucco- lingually, slightly flattened at the cervix, and becoming convex towards the morsal margin, which gives a bell shape to the crown when viewed from the buccal aspect. 16 OPERATIVE DENTISTRY. Tlie morsal surface (Fig. 47) is so different from the sujDerior first bicus- pid that a separate description is necessary. In general outline tliis surface approaches a rounded triangle, tlie width at the buccal, mesial, and distal margins being greater than at the lingual margin. It is surmounted by a prominent buccal cusp which is located nearly in the centre of the surface, and a small lingual cusp, though this is sometimes entirely absent, and its place occupied by a more or less prominent lingual ridge. The buccal cusp has four well-defined ridges descending from it like those of the superior first bicuspid. The buccal ridge arises from the summit of the cusp and descends to the buccal surface ; the mesial and distal morsal ridges usually form a curve with its concavity towards the lingual, and are merged into the marginal ridges to form rounded angles ; the tri- angular or transverse ridge descends towards the lingual cusp or ridge. On either side of this ridge are pits, the mesial and distal pits. The mar- ginal ridges are usually well defined. The central groove sometimes crosses the transverse ridge ; at other times the ridge is divided by a deep sulcus. The cervix is very much constricted, and the cervical line but slightly curved except at the buccal margin. The enamel at this point sometimes forms a prominent ridge. The root is single, flattened laterally, long and slender, occasionally grooved mesio-distally, is rarely bifurcated, and inclined to be crooked. The pulp-canal is small and flattened, and difiicult of access. The diffi- culties are increased by the lingual inclination of the crown and the ten- dency of the root to be crooked. The average length of the inferior first bicuspid is 0.84 inch (2.13 cen- timetres), of the crown 0.30 inch (0.76 centimetre), and of the root 0.54 inch (1.37 centimetres). The inferior second bicuspid resembles the first so closely in general form of both the crown and the root that an especial description, except of its morsal surface, would be unnecessary. The morsal surface (Fig. 48) of the tooth presents the most marked devia- tion in form of any of the bicuspid teeth. It is triangular in outline, like the first, but a trifle larger. The buccal cusp is larger and rounded ; the lingual cusp not quite so fully developed, and divided bucco-lingually, through the centre, by a deep groove, which gives the crown the appear- ance of being a tricuspate. The mesio-lingual cusp or tubercle is some- times develoiDcd at the expense of the disto-lingual, but it is always present. Occasionally it appears as a mere cingule on the disto- marginal ridge. A well-defined triangular ridge descends from each of the cusps, and terminates at the central groove. The marginal ridges are well marked. The central groove is generally straight, but often curved or angular ; the lingual groove is straight, and united with the central groove, forming at the point of union the central fossa. The other surfaces are shown in Figs. 49, 50, 51, and 52. The average length of the inferior second bicuspid is 0.87 inch (2.20 centimetres), of the crown 0.31 inch (0.78 centimetre), and of the root 0.56 inch (1.42 centimetres). Buccal cusp Fig. 49.- -Inferior right second bicuspid, buccal surface. (Enlarged.) FtG. 50. — Inferior right second bicuspid, lingual surface. (Enlarged.) Buccal cusp Fig. .51. — Inferior right second bicuspid, mesial surface. (Enlarged.) Fig. 52. — Inferior right second bicuspiid, distal surface. (Enlarged.) Mesio- buceal cusp Buccal groove Pig. 53. — Superior right first molar, buccal surface. (Enlarged.) Mesio- buceal root Lingual develoj)- mental lobe Mesio- lingual cusp bl Disto- liuecal root Lingual root Lingual develop- mental lobe Disto- lingual cusp Lingual groove Fig. 54. — Sujjerior right first molar, lingual surface. (Enlarged.) Mesio- buccal cusp Mesio- lingual cusp Pig. 55. — Superior right first molar, mesial surface. (Enlarged.) Disto-lingual cusp Disto-buccal cusp Fig. 56. — Superior right first molar, distal surface. (Enlarged.) CLASSIFICATIOX AND DESCRIPTIVE ANATOMY OF THE TEETH. 17 THE MOLARS. The molars, or tuberculate teeth, as they are sometimes termed, are very different in form and architectural design from those which have been pre- viously described. The most simple form of tooth is that designed from the single cone. This is the architectural form of the incisors and cuspids. The bicuspids are more complex, being formed of two cones. But the inferior first bicuspid has but one well-developed cusp and a lingual cin- gule. The superior bicuspids have two well-developed cusps, and the inferior second bicuspids have three cusps. The superior molars are still more comj)lex, being formed by the addition of a third cone to the bicuspid type. This gives the tooth thi-ee roots, upon which three or four cusps are supported. The inferior molars are the most complicated in form of all the teeth, being composed of four cones supporting four or five cusps. There are twelve molars in man, three upon either side of each jaw, above and below. They are situated in the i^osterior part of the jaws, behind the bicuspids, and are designated as the Jirst, second, and tJdrd molars. The third molar is sometimes termed the dens sapientia, or wis- dom-tooth, because of its late erui^tion. The molars occupy the sixth, seventh, and eighth places, respectively, from the median line ; the first molar approximating the second bicuspid distally, the second molar a.])- proximating the first molar distally, and the third molar occupying a similar i)Osition to the second molar. The function of the molars is to crush and triturate the food, and fit it to be acted upon by the gastric juice of the stomach. The loss of these teeth, therefore, seriously impairs the function of mastication, and inevitably leads to various derangements of digestion, and these again to imperfect assimilation and nutrition. The preservation of these teeth, therefore, becomes of vital importance to the individual. The superior first molar is located upon the distal side of the second bicuspid. It is the largest and most strongly marked of the superior molars, and may therefore be taken as the typical form. It possesses three strong roots, and the crown is surmounted by four more or less prominent cusps. In general contour the crown is an irregular quadrilateral, having its angles rounded, two of its sides convex, and two slightly fiattened. The bucco-lingual diameter is a little greater than the mesio-distal, while the height of the crown is about equal to the mesio-distal diameter. It presents for examination five surfaces, — buccal, lingual, mesial, distal, and morsal. The buccal surface (Fig. 53) is formed by the union of the mesio- and disto-buccal developmental lobes, and is divided by the buccal groove into a mesial and a distal half, which are quite similar in outline. This surface is about twice the width of the bicuspids. It is widest at the morsal margin, narrowing towards the cervix, giving a bell shape to the tooth. The morsal margin is surmounted by the mesio- and disto-buccal cusps, which are separated by a deep notch, through which passes the buccal groove to the cervical margin. Sometimes this groove terminates in a pit 2 18 OPERATIVE DENTISTRY. midway between the morsal and cervical margin. Descending from eacli buccal cusp is a longitudinal ridge, — the buccal rklges, — wliicli are at first well defined, but gradually disappear in' tlieir course towards tbe cervix. The Ungual surface (Fig. 54), like the buccal surface, is formed by the union of the two lingual developmental lobes, and is divided into a mesial and a distal half by the Ungual groove. Both halves are smoothly convex in all directions. The morsal margin is surmounted by the mesio- and disto- lingual cusps, the mesial being the larger. The mesial lobe often carries a tubercle or cingule, — a rudimentary fifth cusp. The mesial and distal margins converge rapidly towards the cervix, conforming to the palatal root. The mesial surface (Fig. 55) is nearly flat, except near the morsal margin, where it is slightly convex, and at the cervical margin, where it is some- times depressed towards the lingual or palatal root. The buccal and lingual margins are rounded. The morsal margin is concave in the direction of the root, while the cervical margin is concave in the direction of the morsal surface. The distal surface (Fig. 56) is similar to the mesial surface, except that it presents a somewhat greater convexity, converging more sharply towards the cervix, and more rounded towards the lingual root. The morsal surface (Fig. 57) is surmounted by four rounded cusps or tubercles designated as the mesio-buccal, the disto-buccal, the mesio-lingual, and the disto-Ungual cusp ; the latter being, as a rule, smaller than the others, and sometimes only appearing as a small tubercle. The surface is bounded by four marginal ridges of nearly equal length, — the buccal, the lingual, the mesial, and the distal, — which unite the bases of the cusps. Arising from each cusp and descending towards the centre of the tooth is a triangular ridge. The triangular ridges of the mesio-lingual and disto- buccal cusps unite to form the prominent oblique ridge. On the mesial and distal sides of the oblique ridge are two fossae, the central and distal. The bottom of the central fossa is deeply lined by two of the developmental grooves, the mesial and buccal grooves. The former arises on the mesial surface, crosses the mesio-marginal ridge, and continues in an irregular line to the bottom of the fossa ; the latter begins upon the buccal surface, crosses the bucco-marginal ridge, and terminates also in the central fossa, thus forming the mesio-buccal triangular groove. A supple- mental groove arises from the central pit of this fossa, extending distally across the oblique ridge, which is termed the distal groove. It is rarely well defined, but occasionally it may divide the oblique ridge. The distal fossa is not so large as the central, and is of an entirely differ- ent form, partaking more of the outline of the sulcate groove. This fossa is traversed by a deep developmental groove, the disto-Ungual groove, which arises on the distal margin, follows the line of the fossa, crosses the lingual margin, extending on to the lingual surface to form the lingual groove. When a fifth cusp is present — the mesio-lingual — it is separated from the lingual surface by a groove designated as the mesio-lingual groove. Various supplemental grooves or wrinkles are found upon the morsal surface of the molars, which radiate from these fossae. Buccal groove Lingual groove Fig. 57. — Superior right first molar, morsal surface. (Enlarged.) Lingual ^^H root ^^^IP^^^B Disto- ^^^K^I^H buccal ^^HHB ^|Hk' '^^^^^^^H root ^Hp^I W^^^B^fwr"^"" ' ^^^^1 Mesio- buccal root Cervical margin Buccal groove -Superior right second molar, buccal surface. (Enlarged.) Disto- Mesio- buccal buccal root root Lingual groove Fig. 59. — Superior right second molar, lingual surface. (Enlarged.) Fig. 60. — Superior right second molar, mesial surface. (Enlarged.) Huecal Kri)i)ve Lingua loot Disto- buccal I'OOt Disto-liiigual groove Fig. 61. — Suiif rior right second molar, distal surface. (Enlarged.) marginal ridge Fig. 62. — Suyierior right second molar, niorsal surface. (Enlarged.) Buccal gniove Pig. 63. — Superior right third molar, buccal surface. ( Enlarged. ) Mesial groove Lingual cusp Fig. 64. — Superior right third molar, lingual surface. (Enlarged.) CLASSIFICATION AND DESCRIPTIVE ANATOMY OF THE TEETH. 19 The cervix of this tooth, on section, shows the form of a rounded rhom- boid, widest upon its buccal aspect. The cervical line is nearly straight upon all four surfaces. A concavity occurs on the buccal side at the bifur- cation of the buccal roots, and a slight depression upon the mesial and distal sides, with an inclination towards the lingual root. The root is divided into three prongs or radicles, two upon the buccal side, which are small, tapering, and either flat or rounded, the mesio- buccal and disto-huccal, and one upon the lingual side, large, round, and tapering, the lingual. The roots are usually separated ; their apices stand wide apart. Occasionally, however, they are united for some distance by a bridge of cementum ; this most frequently occurs with the buccal roots. The mesio-buccal is the largest of the buccal roots. All of the roots may be more or less bent and crooked. TJie Fulp- Chamber and Canals. — The pulp-chamber is large and divides into three branches, one for each root. The lingual canal is the largest, and is freely entered to its ax)ex, except in those cases in which the root is bent or crooked. The mesio-buccal is the next largest canal, and can often be entered with ease, but occasionally it is small and narrow, and when the root is crooked it often becomes difficult or impossible to follow it. The disto-buccal canal is almost always so small and fine as to require great skill and much patience to iDroperly cleanse it preparatory to filling. Many times the canal cannot be followed to the apex by any degree of skill or patience, thus making the proi^er treatment and filling of these roots one of the most difficult problems in the whole range of dental XDractice. The average length of the superior first molar is 0.81 inch (2.05 centi- metres), of the crown 0.30 inch (0.76 centimetre), and of the root 0.51 inch (1.29 centimetres). The superior second molar is so nearly the counterpart of the first molar that the differences in its form need only be described. It is a little smaller than the first molar, not so nearly quadrilateral in form, but rhomboidal, being somewhat compressed mesio-distally. The buccal surface (Fig. 58) is almost identical with that of the first molar. A slight difference is noticed in the mesio-distal width of the sur- face and in the location of the buccal groove, which in many instances is at the distal third rather than at the mesio-distal centre. The lingual surface (Fig. 59) presents a greater convexity mesio-distally, and i^articularly so fi^om the linguo-morsal margin to the cervix. The lingual groove is not so constant in its location, often being found between the mesio-distal centre and the extreme of the distal third of the surface. The mesial and distal surfaces (Figs. 60 and 61) have only slight differ- ences. The mesial is inclined to be concaved bucco-lingually ; into this concavity the distal surface of the first molar closely fits, while the only difference in the distal surface is that it is more markedly convex. The Morsal Surface. — The most marked differences in the character of the morsal surface (Fig. 62) of the second superior molar is the almost con- stant tendency to the suppression of the disto-lingual lobe. This carries the oblique ridge farther to the distal side, and enlarges the central fossa. The cusps are also not so prominent, and when the disto-lingual cusx^ is 20 opekatlVe dentistry. only rudimentary in size, and the oblique ridge prominent, the tooth be- comes practically a three-cusj)ed tooth. The various grooves are the same as on the first molar in the normally developed organ. The cervix is less regular in outline and more constricted and flattened mesio-distally than in the first molar. The t^oots are the same in number and general form as in the first molar ; they spread less, however, and are quite inclined to be crooked or converge towards each other, or to be fused together. Sometimes the buccal roots only are fnsed, while in others the mesial and lingual are joined, or all of the roots may be united in a single root, the outlines of the roots being marked only by shallow grooves. The pulp-canals in a normally develoi)ed superior second molar are, as a rule, smaller and more difficult to enter than those of the first molar. When the roots are fused together, all of the canals may coalesce, making a single canal, or when union of the buccal roots takes place these canals may unite. The uncertainty, however, as to their regularity in form adds greatly to the difficulties to be surmounted in the treatment. The average length of the superior second molar is 0. 79 inch (two centi- metres), of the crown 0.28 inch (0.71 centimetre), and of the root 0.51 inch (1.29 centimetres). The superior third molars are smaller than either of the other su- perior molars, and show greater deviations from the normal type, being very erratic as to the time of their ax)pearance and in their form and struc- ture. It is the eighth from the median line, and the last tooth of the upper dental arch. This tooth, when well formed, is a tricuspid, the disto-lingual cusp being suppressed. The oblique ridge then becomes the disto-marginal ridge. The crown is triangular in form and the angles well rounded. The buccal surface (Fig. 63) is like that of the second molar, but more rounded and the lobes less strongly marked and the buccal groove shallow. The lingual surface (Fig. 64) is usually full and convex in all directions. It has but a single lobe on account of the suppression of the disto-lingual cusp. The Mesial and Distal Surfaces. — The mesial surface resembles the same surface of the second molar but is reduced in size, while the distal surface is shorter and more rounded (Figs. 65 and 66). The morsal surface (Fig. 67) in a well-developed third molar presents a 7nesio-buccal, a disto-buccal, and a mesio-Ungual cusp, with the suggestion of a disto-lingual cusp, in the form of a cingule or tiny tubercle. In this case it will also present a central and distal fossa, with the developmental grooves more or less distinctly marked. More often, however, the disto- lingual cusp is entirely suppressed, and with it the distal fossa. Many times the cusps will be so blunted around the central fossa as to give the appearance of a continuous marginal ridge, occasionally sharply defined, or it may be broadly rounded. The cervix is constricted, and in form, on section, gives the outline of a rounded triangle. The roots have very rarely the form of the typical molar in the higher civilized races. As a rule, the roots are fused too-ether to a greater or less Mesial groove Fig. 65. — Superior right third molar, mesial surface. (Enlarged.) Distal groove Fig. 66. — Superior right third molar, distal surface. (Enlarged.) Buccal groove Disto-buccal groove Buccal groove Mesio-lingual cusp Fig. 67. — Superior right third molar, morsal surface. (Enlarged.) Fig. B. — Inferior right first molar, buccal surface. (Enlarged.) Mesio-linjfual cusp ])ist()-liii!Jual cusp Lingual groove v! 1 ' -'■ Disto- morsal Biarffin Fig. 69. — Inferior right first molar, lingual surface. (Enlarged.) Fig. 70. — Inferior right first molar, mesial surface. (Enlarged.) Median- Buccal groove buccal cusp Disto-huccal groove Fig. 71.— Inferior right first molar, distal surface. (Enlarged.) Lingual groove Fig. 72. — Inferior right first molar, morsal surface. (Enlarged.) CLASSIFICATION AND DESCRIPTIVE ANATOMY OF THE TEETH. 21 extent, sometimes forming a single root, and they are often curved distally towards the maxillary tubei'osity. Sometimes they have multiple roots, which may be curved in various directions. The pulp-canals are usually blended into one, but when the roots are separate there are individual canals. The difficulties presented in the treatment of the root- canals of these teeth are greatly enhanced by the positions which they occuiDy in the jaw and their great liability to have crooked roots. The average length of the superior third molar is 0.68 inch (1.72 centi- metres), of the crown 0.24 inch (0.6 centimetre), and of the root 0.44 inch (1.11 centimetres). THE INFEEIOE, MOLARS. The inferior molars are three in number, and are designated according to their positions in the jaw as the first^ the second^ and the third. They occupy respectively the sixth, seventh, and eighth positions in the inferior arch from the median line. As already stated, these teeth are constructed upon the architectural de- sign of a combination of four cones united at their bases to form the crown, while the apices are united in pairs to form the mesial and distal roots. The inferior molars differ from the suj^erior in that they have two roots instead of three ; are inclined to have multiple cusps ; have a greater diameter mesio- distally than bucco-lingually ; and the buccal surface slopes towards the centre of the tooth to accommodate the over- locking of the cusps of the occluding teeth. The inferior first molar is the sixth tooth from the median line, and approximates the second bicuspid u^^on its distal surface, ^'l^exttothe superior first molar it is the largest tooth in the denture." (Black.) The buccal surface (Fig. 68) is an irregular trapezoid in form, the morsal margin being wider than the cervical, due to the convergence of the mesial and distal surfaces towards the cervix. The surface is convex in all direc- tions, and the mesial and distal margins are rounded. The morsal margin is usually surmounted by three cusps or tubercles, the mesio-buccal, the me- dian-huccal, and tine disto-huccal, which are separated by the buccal and disto- buccal grooves. The buccal groove is a little to the mesial of the centre of the tooth, while the disto-buccal groove is near the disto-buccal angle. These grooves generally terminate near the middle of the surface in pits, which often become the seat of caries. The lingual surface (Fig. 69) is slightly convex in all directions, and in- clines towards the lingual. The surface is not so wide as the buccal sur- face on account of the convergence of the mesial and distal surfaces towards the lingual. The morsal margin forms a rather sharp angle with the mor- sal surface ; it is surmounted by two cusps or tubercles, the mesial and dis- tal, and is divided through its centre by the lingual groove, which separates the mesial and the distal cusx)S. This groove is shallow and rarely extends farther than the middle of the surface. The mesial and distal surfaces (Figs. 70 and 71) are flattened bucco-lin- gually and convex from morsal margin to cervix, the distal surface more than the mesial. They are wider at the morsal margin than at the cervix. 22 opp:rative dentistry. The mesio-morsal margiu is deeply concaved, and the disto-morsal margin is notched, sometimes deeply, by the distal groove. The morsal surface (Fig. 72) is trapezoidal in form, the buccal side being the longest. The surface is surmounted by five cusps, designated as fol- lows : the 7iiesio-buccal, the median-huccal, the dlsto-buccal, the mesio-lingual, and the disto-Ungual ; three are arranged upon the buccal half of the sur- face, and two upon the lingual. The cusps are united at their bases by four marginal ridges, the mesio-marginal ridge, joining the mesio-buccal and the mesio-lingual cusps ; the hucco-marginal ridge, uniting the mesio-buccal,, median-buccal, and disto-buccal cusps ; the linguo-marginal ridge, joining the mesio-lingual and disto-lingual cusps ; and the disto-marginal ridge, uniting the disto-lingual and disto-buccal cusps. These ridges slope towards the centre of the teeth to form the central fossa. There are five triangular ridges which descend from the five cusps towards the centi-al fossa. The morsal surface is traversed by five developmental grooves, the mesial, buccal, disto-buccal, lingual, and distal. The mesial groove arises in the central fossa and crosses the mesio-margi- nal ridge to the mesial surface ; the buccal groove begins at the central fossa, crosses the bucco-marginal ridge between the mesio- and median-buccal cusps to the buccal surface ; the disto-huccal groove takes a disto-buccal di- rection from the central fossa, dividing the bucco-marginal ridge between the median- and disto-buccal cusps ; the lingual groove has its origin in the central fossa, crosses the linguo-marginal ridge in a deep sulcus between the mesio- and disto-lingual cusps, and is lost uiDon the lingual surface. The distal groove arises also from the central fossa, crosses the disto- marginal ridge dividing the disto-lingual cusp from the disto-buccal. Various other pits and supplemental grooves are occasionally observed. The cervix on section is rectangular in form, with the sides slightly con- caved in the centre, and deepest at the buccal and lingual sides at the begin- ning of the bifurcation of the roots. The cervical line is convex upon the buccal and lingual sides, and concave upon the mesial and distal. The roots are two in number, the mesial and the distal. They are long, flattened mesio-distally, and often have a decided distal curvature. They are implanted in their alveoli, with their long diameter in a trans- verse direction to the jaw. The distal root is larger and more rounded than the mesial, the latter having deeper grooves and a greater tendency to bifurcation. The pulp-canal is formed like the teeth, with two branches. Occa- sionally the mesial root will have two canals. The distal canal is the largest and quite readily entered, while the mesial canal is inclined to be flat or hour-glass-shaped, showing the tendency of this root to bifurcate. When separate canals are formed, they are usually very small, and often cannot be followed. The average length of the inferior first molar is 0.82 inch (2.08 centi- metres), of the crown 0.30 inch (0.76 centimetre), and of the root 0.52 inch (1.32 centimetres). The inferior second molar differs from the first in that it has but four instead of five cusjds, is more quadrangular, rounded, and symmetrical. Buccal Mesio-buccal cusp groove Mesio-lingual cusp Central fossa Mesio- l)uccal Mesio- lingual cusp cusp Lingual Buccal pit; groove Mesial root Fig. 73.— Inferior right second molar, buccal surface. Fig. 7i.— Inferior right second molar, lingual surface. (Enlarged.) (Enlarged.) Mesial groove Distal groove Disto- lingual cusp < Disto- huccal cusp Fig. 75. — Inferior right second molar mesial surface. (Enlarged.) Fig. 76. — Inferior right second molar, distal surface. (Enlarged.) Xi'siiil KHxiyo Median Pisto-linKual cusp Ijuecal cusp Mesio-liuccal cusp Mesio- Imccal cusp l)ist(.- buccal CUSJI Buccal inarKinal 1 inccal cusp Median-buccal cusp Buccal groove Fig. S2. — Inferior right third molar, morsal surface. (Enlarged.) CLASSIFICATION AND DESCRIPTIVE ANATOMY OF THE TEETH. 25 deciduous teetli, whicli allows tlieir crowns to fall away, begins in the cen- tral incisors at about thefoiirth year, and is completed at about the seventh. In the lateral incisors this xDrocess begins at about the fifth year, and is completed at about the eighth ; while in the cuspids it is delayed until the ninth year, and completed at the twelfth. The superior first deciduous molars are unlike the molars of tlie permanent set in that the crown has but three lobes or cusx)S, mesial, distal, and lingual, which are divided by three developmental grooves, the mesial, distal, and huceal. The cusps converge towards the centre of the crown, giving the morsal surface the appearance of being smaller than the base of the crown. The cervix is constricted, while the enamel ends so abrui^tly at the bucco-cervical margin as to form a prominent ridge,— the huceal ridge. Another distinctive feature is that the marginal ridges, triangular ridges, and angles are more acute than in the i:)ermanent molars. Its greatest diameter is bucco-liugually. The superior second deciduous molars are larger than the first ; the morsal surface is wider, and is surmounted by four cusps, and in other ways the x)rototyx)e of the superior second permanent molar. The inferior deciduous molars are similar in general form and out- line to the permanent molars. The first molar has four cusps uj^on its morsal surface, while the second molar, unlike the second iDcrmanent molar, has five cusps. The cusps and the marginal and triangular ridges are more marked and prominent ; the central fossa is large and deei), being sometimes divided by the triangular ridges forming two or more fossse or I)its. The cervix is constricted and the bu ceo -marginal ridge prominent. The mesio-distal diameter of the crown is greater than the bucco-liugual. The roots of the deciduous molars differ from the permanent in that they are relatively thinner and longer, and are much more spread or divergent to accommodate the crowns of the succeeding bicuspids. The imlp-chamher is i^rox^ortionately much larger than in permanent molars, but the root-canals are thin and narrow, making their treatment difficult. The process of resorption in the roots of the first molars begins at about the sixth year, and is completed at tlie tenth, while for the second molars it begins at about the eighth year and is completed at the eleventh. CHAPTEE 11. OEIGIN, DEYELOPMENT, AND MOEPHOLOGY OF THE TEETH. Definition. — Morphology (from the Greek p-opcj)-/]^ form, and X6yu<;^ a dis- course). The science of biologic forms, including their relations, changes, and analogies ; the science of the shape and modifications of organs or parts considered under the idea of unity of plan. Anatomists until quite a recent period have looked upon the teeth as members of the osseous framework of the body, but they are now classified as portions of the dermal skeleton. This change in the classification was brought about by prolonged study and research into their origin and de- velopment. The invention of the compound microscope has made it possible for the scientist to delve into the hidden mysteries of nature and reveal to the world the wonders of many of her processes and the secrets of her labora- tories ; to picture the wonderfully minute elemental or embryonic cells from which organized structures are formed, and the marvellous delicacy and precision with which these are arranged in the building of tissues and organs. The discoveries made by the microscope during the last three or four decades in the morphology and the histology of vegetable and animal tissues, and in pathology and bacteriology, have been truly wonderful, and in no department of science have greater discoveries been made than in that department of medicine known as dentistry. The researches of Hunter, Bell, and Goodsir marked the beginnings of dental morphology and histology, and prepared the way for the later inves- tigations into the evolution of the teeth. The errors into which these earlier investigators fell were due largely to the non-possession of adequate facilities for studying the minute structures of the embryonic tissues. With the higher powers of the microscope it became possible to delve deeper into the mysteries of the evolution of the dental tissues than these old masters had been permitted to do. The re- sults of these investigations have proved conclusively that the enamel- organs had their origin in the epithelial tissues, and hence were formed from the same tissue elements as the hair, the nails, and the epithelial lining of the glandular structures of the skin and the mucous membrane, — namely, epithelial cells. EVOLUTION OF EPITHELIAL TISSUE. In order that the student may approach the subject of the evolution of the teeth with a clear understanding of the tissue elements which eiiter into their structure, it will be advisable to present in brief review the morphology and the character of epithelial tissue in general. In all animals which are developed from an ovum (Fig. 84), as soon as impregnation has taken place and the proper conditions of incubation are 2o Fig. S4. — Graafian follicles, or ova, in various stages of development. >( : Fig. 86. — Transverse section of embryo of cliick, eighteen, liours incubation, sliowiug epiblast and hypoblast. (After Aby.) Fio. 87. — Transverse section of embryo of chick, twenty-four hours incubation. (After Aby. Fio. 88. — Transverse section of embryo (if cliick, tliirly-six liours iiirubation. (After Aby.) Epidermis Fig. 89. — Vertical section of human skin. >( ,S7 Cuticle Fig. 90. — Vertical section of skin of middle finger. )< 50. Fig. 91. — Squamous epithelium from buccal cavity. A, squamous epithelial cells ; B, salivary corpiuscles. X 162.5. (V. A. Latham). Pig. 92. — Longitudinal sectioiL of lip of kitten, v .SO. ORIGIN, DEVELOPMENT, AND MORPHOLOGY OF THE TEETH. 27 Division of mammal ovum (half diagrammatic). 1, the yolk divided into two 'globules (cells) with nuclei ; 2, quadrupled ; 3, a large number of nucle- ated cells ; 4, a, b, isolated cells. established, — and this is best studied in the egg of the bam fowl, — there occurs a rapid proliferation of embryonic cells in the germinal spot or disk of Pander. This disk is at first composed of a germinal cell, which by the process of karyokine- sis — indirect division or segmenta- tion of the cell — produces a rapid multiplication of these elemental cells (Fig. 85, 1, 2, 3, 4). These embryonic cells soon ar- range themselves into two layers, known as the epiderm or epiblast, and the hypoderm or hypoblast, the epiblast forming the upper layer and the hypoblast the lower (Fig. 86). Later a third stratum of cells is developed between the epiblast and the hypoblast, which is known as the mesoderm or mesoblast (Figs. 87 and 88). From these three layers all of the tissues and the various organs of the body are developed. From the epiblast are developed the various layers of the skin (Fig. 89), — viz., the epidermis, or cuticle, the derma, or true skin, and the rete mucosum, or Malpighian layer, — the glandular ap- pendages of the skin, the hair, the nails, and the entire nervous system. From the hypoblast are developed the lining mucous membrane of the alimentary tract, of the air-passages, of the genital apparatus, the epithe- lial linings of the serous cavities, the lining membrane of the heart, the blood and lymphatic vessels, and the enamel organs of the teeth. From the mesoblast are developed the remaining portions of the body, — viz., the bones, muscles, blood-vessels, lymi)hatic vessels, connective tissue, etc. Epithelial cells are common to both the skin and the mucous membrane, their peculiar characteristics depending upon their location and their par- ticular function, as, for instance, in the skin (Fig. 90) they may form the cuticle, or horny layer, when they are squamous or scaly in shape (Fig. 91) ; if forming the lining of a tubule of a sweat-gland they are cuboidal ; when entering into the formation of the hair-sheath they are columnar (Fig. 92), while in the shaft of the hair they become squamous, the cells being over- laid like the scales of a fish (Fig. 93). In the development of the nail-plate they are also columnar, but rapidly become squamous and cornified. In the mucous membrane of the mouth the most superficial layer of epithelial cells is of the squamous variety, while beneath this lies a layer of spinous or furrowed cells, the spines of which interlock with neighboring cells, and by this means are held together. Immediately beneath this stratum is another, the Malpighian layer, made up of small, soft, roundish cells, sometimes oval in form, and arranged in a regular order, standing 28 OPERATIVE DENTISTRY. Section of jaw of rab- bit embryo, sliowing dental ridge cut across : ec, oral epithelium ; e, epithelial outgrowth cor- responding to future enamel organ ; m, meso- blastic tissue. upright upon the basement membrane (Figs. 94 and 95). Other peculiar epithelial cells found in the mucous membrane of the mouth are known as the ciliated columnar cell (Fig. 96) and the goMet-cell (Fig. 97), the functions of which with the mucous gland are to secrete mucus. The mucous glands are also lined with epithelial cells, usually in a single layer, and cuboidal or columnar in form. From the deeper strata of epithelial cells, the Malpighian layer of the mucous membrane, the enamel organs of the teeth are formed. It is interesting to note the analogy in the mor- X^hology of the teeth and the hair. By comparing Figs. 98 and 99, it will be seen that the first rudiments of the tooth-follicle and the hair- follicle have their origin in the lower layer of epithe- lial cells, — MaliDighian layer, — which dips down into the embryonic tissue of the mesoblast. The likeness can be still further traced in the formation of the pa- pillae and the invagination of the flask-like bud, (See Figs. 100 and 101.) Until 1837, when Goodsir published his theory of the evolution of the teeth, there had been no dis- tinct, formulated teaching upon this subject. This theory was at once adopted by anatomists generally, and was incorporated into all standard works on anatomy and histology. Huxley, Kolliker, Waldeyer, Kollman, and Guillot were the first to cast doubt ux3on the correctness of the theory of Goodsir. In 1860 there appeared a treatise by Eobin and Magitot, entitled ''The Genesis and Development of the Dental Follicle to the EruiDtion of the Teeth ;" this xd roved the Goodsir theory to be based upon errors due to methods of manijDulation. It also contained serious errors in the order of the genesis of the dental tissues, the most conspicuous of which was the statement that the dentin First rudiments of a hair from the bulb WaS the first part of the follicle tO human embryo of sixteen weeks, a, b, y.^, formed layers of cuticle ; m, m, cells of the rudi- mentary hair ; i, hyaline envelope. It was not, however, until the appear- ance of the treatise ' ' The Origin and For- mation of the Dental Follicle," by Legros and Magitot, that the Goodsir theory was fully overthrown. The teaching of these authors has stood the test of more than thirty years of investigation without a single imx)ortant statement having been successfully controverted. Many facts, however, in relation to the develop- ment of the individual dental tissues have since been discovered and be- come a part of dental histology. We may, therefore, feel fairly certain that in so far as the evolution of the dental follicle is concerned, we are resting upon a solid, scientific foundation. Fig. 99. Fig. 93. — Transverse section of hairs of scalp. ;< fiO. Fig. P4. — Epithelial layer of tiie mncons membrane. A, squamous cells ; JJ, columnar ttells. (R. R. Andrews.) Fig. 95. — Columnar epithelial cells. •, ( 670. Columnar : epithelial :■ cells' Goblet- • cells Fig. 97.— Goblet-cells. X 500. Invaginatin^ enamel organ j Dentin papilla; Enamel-organ before invagi- nation yiG. 100. — Lower jaw of human embryo, ninth to tenth week. >C HO. Shaft of hair Invagi ' ^ ^i nated bulb ' ^, Papilli ' a ii ~ i< ^ ' Fig.. 101. — Vertit-al Hectinn of the skin, sljuwintr hnllicins ends of two hairs. :< ^^. Develop- ^' ^^ ingdecid-F iious tooth I •pr^--^"^^ Upper Jaw ^ecMiiidary ■ ■jiithelial roni Secondary I'liithelial cord T.dwer jaw >•> ' Fig. 103. — Vertical secjtion through head of human foetus, showing completed rudimentary jaws, etc. X 80. Develop- ing tooth Develop- ing bone Fig. 104. — Lower jaw of human fcetus, showing Meckel's cartilage. ;< 80. OEIGIlSr, DEVELOPMENT, AND MORPHOLOGY OF THE TEETH. 29 Before proceeding to a study of tlie accepted theory of the evolution of the teeth let us briefly review the theory of Goodsir. Goodsir stated that at a very early period of foetal existence a depres- sion or groove, which he termed the primitive dental groove, was formed in the mucous membrane along the entire circumference of the alveolar border of both jaws ; that from the bottom of this groove in each jaw papillae arose, ten in number, isolated and uncovered, which represented the future deciduous teeth ; that later these papillae became closed in by the approach- ing of the walls of the groove and by the formation of separate septa between the papillae, thus enclosing each of them in an independent follicle. The permanent teeth, except the molars, were formed in like manner, within what he termed the secondary dental groove, which he located behind the primitive dental groove, and formed from the inner or lingual lip of the primitive dental groove. In this secondary dental groove were formed the ten anterior permanent teeth, — the teeth of replacement, — while the first permanent molar was evolved within the posterior portion of the primitive dental groove, which had remained open for this purpose ; and the second permanent molar is developed from a papilla given off from the first perma- nent molar at the seventh or eighth month after birth, and the third molar from a papilla given off from the second permanent molar at a still later period in childhood. A study of the origin and development of the teeth should take into account, also, the evolution of the jaws, which may be briefly outlined as follows : THE EVOLUTION OE THE JAWS. In the human subject the first evidence of the formation of the superior maxilla is seen very early in the life of the embryo, — viz., at about the eighteenth day after conception, by the develop- ^ ment of four tiny buds, tubercles, or processes ^_"^ ^ _ " " near the central portion of that surface of the yg^^^m^^^^^ rudimentary head which is destined to form the ^p B ^^^ face (Fig. 102), and which are denominated the ^^ ^^^ ;^BL superior or frontal processes or tiibercles, and the ^^'' '^^^'^j^^^ lateral, oblique, or maxillary processes or tubercles. ^^ . ^WW -^^'^P''^^' ^ The superior processes elongate downward, ^ ^p w CT ^ m ""iSf" ^ and at the same time api^roach each other ^' 41^^^*^^^ ^ towards the median line, where they finally ^^^^^P^H^^^ coalesce, at about the twenty-fifth day, to form ^^^htjiTiw^^^^ the intermaxillary bones and the central por- f^d^ Hjj^ tion of the upper ll]). The lateral processes W^lf ^l|l likewise elongate, and apj) roach each other '' | towards the median line, where they finally, at Head of human embryo. (His.) about the twenty-eighth day, meet the superior ^' ^' ^^p^^^^^ processes; b, B,oh- •J ^ "^ ' ^ lique processes. processes, and unite vfith them, thus forming the lateral halves of the rudimentary superior maxillary bone, palate bones, the cheeks, the lateral portions of the upper lip, and the velum palati (Fig. 103). 30 OPERATIVE DENTISTRY. Coincidently with the development of the superior maxillae, a simi- lar process of development has been going on for the formation of the inferior maxilla. At about the eighteenth day two similar tiny buds or processes appear just beneath the lateral processes, and grow rapidly to- wards the median line, where they unite at about the twenty-eighth day, and complete the arch of the lower jaw. Very soon afterwards a little cartilaginous hand makes its appearance within the central portion of the rudimentary jaw, MecJceVs cartilage (Fig. 104). This cartilaginous band is composed of two parts, which arise from the mallei of the ears, and extend forward until they unite at the mental symphysis. Meckel's car- tilage gives form and stability to the inferior maxillary arch until ossifica- tion takes place, when it disappears by absorption or becomes calcified, forming a part of the maxillary bone. EVOLUTION OF THE TEETH. The earliest evidences of the evolution of the teeth are to be found at about the seventh week of intrauterine life, in the shape of a depression or involution of the Malpighiau stratum of the epithelial cells upon the alveolar border of the rudimentary jaws (Fig. 105), forming what is known as the epithelial band. This band is composed of the same cell elements that are found in the epithelial tissue of the " ^^t'^'f «^^ ^ oral mucous membrane, the band or groove Involution of the Ma'ipighian stra- being bouudcd by a layer of columnar or turn. Section of jaw of rabbit embryo, prismatic cclls, which include a mass of showing thickening of epiblastie epi- t -, -i -, tjt ti ,-, -,-, ■ ji theiium (ec) from which the Maipigh- polyhedral nucleated cells, the cells m the ian stratum (e) begins its growth into centre oftcu being of the denticulated or the mesoblast (m) to form the epithe- . . , liaiband. (Piersoi.) spinous Variety. This band or groove, as it descends into the embryonic tissue of the jaw, curves slightly inward, and is filled and heaped u]j with flattened epithelial cells, making what is known as the dental ridge, the maxillary rampart Of Kdlliker, Waldeyer, and Kollman. The next step in the evolution of the dental follicle occurs between the seventh and eighth weeks, when the epithelial band or groove sends off a thin lamina or process upon its lingual aspect in each jaw, — the epithelial lamina, — which occupies a horizontal position to the epithelial band. Buds or processes also appear upon the extremity or edge of the lamina, — the primitive epithelial cord, — which elongates and dips down into the embryonic tissue of the jaw. At about the eighth week the enamel-organs are clearly defined as club-shaped enlargements upon the extremities of the primitive epithelial cords (Fig. 106), and the dentin papillce, or dentin bulbs, can be discovered as opaque points directly beneath the enamel-organ in the meso- blastic tissue. Fig. 107 represents the epithelial cord in the i)receding illustration, highly magnified, and Fig. 108 shows the same in cross-section. The process of evolution advances synchronously at this period in all the follicles of the deciduous teeth. Ym. ion. — Lower jaw of human embryo, seventh to eighth week. X 75. K])ithelial lamina Polyhedral, ui flatten I'll epithelial cclN I 'l\ib-shaped en- largement of the ipithelial cord Fig. 107. — "Vertical section of epithelial cord, or primitive enamel-organ. X 300. -■T^t -f^x, iJa iiiS' Epithelial cord V. r-ftL^ Fig. 108. — Cross-section of epithelial cord. ~< .SOO. Fig. 109. — Primitive epithelial cord, showing a jieculiar turning of the end. X 45. ■In.v>agwiation, of enamol-organ Dentin papillffi Invagination of enamel-organ Fig. 110. — Vertical section through lower jaw of embryo field nionse. Primary epithelial conl Dentin papillas Bud to form the secondary epi- thelial cord Enamel-organ Fig. 111. — Evolution of dental follicle at about the ninth week, showing invagination of enamel-organ. X 70. odontoblasts iJentin jiapi 11:13 Sat: wail Fill. 11'2. — Developing human cuspid. Enamel-organ Membrana eboris Dentin papilla; Constriction at base of papillae Blood-vessel Blood-vessi'l External epithe- lium of enamel- organ Membrana eboris Internal epithe- 'ium of enamel- organ Blood-vessel Sac of follicle Forming Bone Fiii. 113. — Follicle of Innnan molar at about the eleventh week. ; ."iO. OEIGIN^ DEVELOPMENT, AND MORPHOLOGY OF THE TEETH. 31 The club-like enamel-organs now rapidly enlarge and become pear- shaped in form. In Fig. 109 a peculiar hook-shaped termination is noticed, which is doubtless a malformation, as no reference is made to it by other observers, and has not been seen before by the writer. This pear-shaped enlargement is due to a rapid proliferation of the polyhedral epithelial cells contained within them, and of the columnar cells which form the outer boundary. The enamel- organ has now attained its full size, and occupies a position within the deeper structures of the jaw, and slightly inclined towards its lingual aspect. The next important feature in the development qf the follicle is the in- vagination of the enamel- organs, as shown in Fig. 110. This change occurs simultaneously with the appearance and growth of the dentin papillae. Immediately beneatli each enamel-organ is developed from the mesoblastic tissue a cone-shaped bulb or papilla similar to the papillae found in the gums and mucous membrane of the mouth. The dentin parpillm (Fig. Ill) in its earliest stage of development is com^ posed simply of embryoplastic neucleated cells, but soon afterwards it con- tains fusiform and stellate cells ; it also contains a vascular loop, but Eobin and Magitot were unable to discover in it any nerve-fibres. As soon as this new organ has assumed a conical form, which occurs at about the ninth week, there arises from its base, as seen in microscopic sections, two opaque i^rocesses, which are the first traces of the wall or sac of the future follicle. These processes, which really surround the base of the papillae like a collar (Fig. 112), elongate as the bulb increases in size and length, converging towards each other until they finally embrace the bulb and enamel-organ in their entirety. As the dentin bulb enlarges and elongates it comes in contact with the inferior portion or lower plane of the enamel-organ, which is gradually carried upward until it is completely invaginated, thus forming a double- walled caj) or hood over the dentin jjapilla. It is interesting to note the fact that during the growth of the dentin papilla and the invagination of the enamel-organ a reciprocal adaptation of these organs takes place from the commencement of the process, and continues throughout all subsequent phases, the enamel-organ at all times covering the dentin bulb, and being adapted to its varying con- tours (Fig. 113) . At no time, however, during the process of development do the tissues of these two organs become united. Sudduth confirms the teaching of Legros and Magitot, and says there is no union between the enamel-organ and the papilla, nor have vessels or nerve-fibres ever been demonstrated as j)assing from one to the other. Bodecker takes an opposite view, and states that when the enamel- organ is detached from the dentin papilla, as frequently occurs in making sections, there appears upon the outer surface a delicate fringe, which he believes to be the true connection between the enamel-organ and the papilla. Fig. 114 is here introduced to show the stage of general development of the human embryo at the eleventh or twelfth week. At about the eleventh week a notable change has taken place in the 32 OPERATIVE DENTISTRY. shape of tlie dentin papillae, wliich have now assumed the forms of the crowns of the teeth which they represent. At this time, also, a narrowing or constriction takes place at the base of the papilla, forming a kind of neck at the free border of the enamel-organ (Fig. 113). In examining vertical sections of the dentin bulb at this period, the existence of a thin, clear, transparent zone of amorphous material upon the periphery of the organ is discovered. This amorphous material is destitute of anatomic elements, somewhat more transparent and denser than the subjacent tissue of the dentin papilla, and capable of being de- tached from the surface of the latter. This condition led Raschkow and others to suppose the papilla to be invested with a distinct membrane, the memhrana prcBformativa of Easchkow, and the membrana eboris of later writers. This zone of amorphous material lies between the enamel-organ and the dentin x)apilla (Fig. 115). Black, in siDcaking of this layer, says, ^' Just before the calcification, and even before the odontoblasts make their appearance, the ameloblasts and the tissues of the pulp are separated by a well-marked double pellucid layer, which in section appears as a double band." Andrews says, ''If the tissue has been carefully prepared, minute glistening bodies — calco- sjpherites — are seen under the higher powers of the microscope, in the den- tin bulb and within this layer, which indicates the near approach of the process of calcification. The first layer of odontoblasts is formed within the transparent amorxDhous material, and although the ameloblasts make their appearance first, calcification does not take place in them until after the odontoblasts have formed a caj) of calcified dentin upon which the enamel-rods are to rest (Fig. 116). The character of the cells contained within the body of the enamel- organ have also become greatly changed, and appear as stellate bodies within a reticular structure (Fig. 117). The next important change in the process of development is seen at about the sixteenth week, in the form of a tiny but well-defined cap of calcified dentin at the tips of the incisors and cuspids, and about a week later in the molars (Fig. 118). Calcification has not yet begun in the amel- oblasts, although they are fully developed and well defined. The primi- tive epithelial cord is still attached to the enamel- organ, and the sac is not yet closed. Another important change also takes place at this time, — viz., the budding of all the primitive cords upon their lingual aspect to furnish the enamel-organs for the ten anterior permanent teeth in each jaw. The buds rapidly assume a pear-shaped form, as shown in Fig. 119, followed by the appearance of the dentin papillae and invagination of the enamel-organs shown in Fig. 120. Black believes the epithelial cords of the permanent follicles often spring directly from the Malpighian layer of the epithelial band (Fig. 121), instead of from the primitive epithelial cords, as taught by Legros and Magitot. At the eighteenth or nineteenth week the sacs of the primitive dental follicles are closed, and the follicles separated from their epithelial cords Fig. 114. — Human embryo at eleven to twelve weeks after conception. • ' •■ '. '7' ' - - stellate reticulum • - ' , ^ • - Amelo- blasts _ - Calco- spherites -- ^i«Kat_: stratum %^)-^. .- interme- dium Dentin papillae - . ~ First lay- (!-( of odonto- blasts ( 'apillary blood- \ ossel Capillary blood- vessel - i» .f.f 'i Fig. 115. — Vertical section of human molar at junction of enamel-organ with dentin papilte, showing earlj' stage of cell differentiation and zone of amorphous material. (V. A. Latham.) X 300. Embryonic connective tissue External epithelium of enamel-organ Stellate reticulum Stratum intermedium Ameloblast^ "^i Calcified dentin' _ _ — »,, „ Dentin papill^i^ - - ^^^ Forming ameloblasts '( )dontoblasts Fig. 116. — Vertical section of incisor of human tcetus (partly diagrammatic). \ '^^. formed ■y \ '^fe. enamel Fig. 117. — Oblique section of a dental follicle, showing stellate reticulum of the enamel-organ, x 83. Enamel Enamel-organ Uncalcified cusp lieiitin 3^K4 ^ ji Dentin j>aplll8e Forming bone Fig. 118.— Vertical section of human molar, showing early stage of calcification of dentin and enamel. X 90. 1 inthelial cells Budding of the primitive ejn thelial cord Primitive epithelial cord Enamel-organ Dentin papillae Fig. 119. — Vertical tsection of cuspid of human f i tus showing tlic budding of the primitive epithelial cord. X 70. Enamel-organ, permanent tooth Dentin papillae Follicle of deciduous tooth Fig. 120. — Vertical section of human fcetal maxilla, showing the deciduous follicle and pear-shaped enlarge- ment and commencing invagination of the enamel-organ of the permanent cuspid. X 70. Dentin papillae Enamel- organ Fig. 121. — Vertical section of incisor tooth, human embryo. Superior maxilla. (V. A. Latham.) x 50. Forming bone Fig. 1'22. — Section of human developing tooth, showing the follicle closed and the primary epithelial cord severed from its enamel-organ. Fig. 123. — Vertical section of dental follicle of cat, showing the follicle closed, x 9. CHAPTEE III. HISTOLOGY OF THE DENTAL TISSUES. Calcification.— In the preceding chax^ter the process of development of the dental organs was studied to the stage of calcification of the dentin and enamel. It was then noticed that although the enamel-organ was the first to be formed, and that a layer of specialized columnar epithelial cells, the ameloMasts, were arranged in a definite order resting upon the coronal surface of the dentinal papilla or dentin germ (Fig. 126), apparently ready for the process of calcification ; it is not until later that the deposition of lime salts really begins for the formation of the enamel. The formation of the dentin begins first by the development of a layer of specialized connective-tissue cells, the odontoblasts, covering the dentin germ -, and these immediately begin the process of building the first tiny cap of den- tin u]3on each of the lobes or centres of calcification by the deposition of lime- salts. The odontoblastic cells, which are clearly defined, are somewhat broader than the ameloblasts, which are situated immediately above them, and are arranged in a single layer. They are at this stage ovoid in form, and are apparently embedded in a transparent and structureless gelatinous sub- stance, in which small globular masses — calcospherites — are already forming. The function of the odontoblasts is to superintend the process of calci- fication of the dentin by the deposition of calcific material, layer within layer, upon the coronal surface of the dentin germ, which by this pro- cess constantly decreases in size until the limit of nature is reached. The function of the ameloblast is also that of superintending the laying down of the lime -salts which are to form almost the entire bulk of this tissue. Definition. — The term calcification comes from the Latin, calx, lime, and fiere^ to become, — to become lime j hence the term is used to express the physiologic process by which a deposition of calcium salts, or other insoluble crystalline matter, is laid down within an especially prepared matrix, as in the formation of bone, cementum, dentin, and enamel ; or a pathologic deposition of calcareous materials within tissues where they do not normally belong, as in the calcification of the arteries, inorganic deposits within serous membranes ; the calcification of tubercular deposits, etc. By the physiologic process of calcification various tissues are formed or built up, — by the aid of especially endowed cells, — like bone, cementum, dentin, and enamel. The exact modus operandi by which this process is accomplished has not been fully established. 34 Dentin papillae ^-Mi^^M Tig. 126. — Section of dental follicle, showing first layers of ameloblasts an.l mlouiolilasts. ;< 1000. *^ .'**». -§^ ' Fig. 127. — Section of human femur, six mouths' fiulus, showing osteoblasts. X 109. # 1-"IG. 1:2S.— Forming dentin, showing odontoblasts. (V. A. Latham.) X 1000. J^- Fig. 129.— Enamel-cells, with nuclei. (R. R. Andrews.) HISTOLOGY OF THE DENTAL TISSUES. 35 That tliese especially endowed cells, osteoblasts, or bone-builders (Fig. 127), cementohlasts, or cement-builders, odontoUasts, or dentin-builders (Fig. 128), and amelohlasts, or enamel-builders (Fig. 129), are tlie active agents in the construction of tliese tissues is a generally conceded fact. The term used to express calcification of the bone is ossification ; in the calcification of cementum, cementification ; in the calcification of dentin, dentinification ; and in the calcification of enamel, amelification. The process in the first three of these is substantially the same. There are two methods by which a calcified tissue may be formed, — one by the deposition of calcium salts within the substance of a formative organ, thus converting it into a calcified structure 5 and the other by a formative organ excreting from its surface both organic and inorganic constituents. The former method is the process by which bone, cementum, and dentin are formed ; while the latter is the process by which the shells of many mollusks are developed, and by most histologists thought to be the method by which enamel is built up. The calcium and other salts necessary for the calcification of these tis- sues are held in solution or in minute particles, so small as to be almost beyond the reach of demonstration by the highest powers of the micro- scope, in the gelatinous or protoplasmic fluid in which these specialized cells are embedded. It is from this fluid or semi-fluid medium, the inter- cellular substance, charged with these salts, that the cells derive the neces- sary pabulum for their nourishment and for the performance of their func- tions. The supply of nourishment is derived and maintained by the abundant vascular net-work of the neighborhood. Eainey discovered, and Professor Harting and Dr. Ord further eluci- dated the fact, that the calcium salts in the presence of albuminoid sub- stances are changed chemically, uniting with the organic compounds to form small globular bodies which were afterwards called calcosplierites. These bodies are always present in the intercellular substance just before and during the process of calcification. • Eainey found in exj)erimenting with the calcium salts that if calcium carbonate be slowly formed in a thick solution of mucilage or albumin, it resulted in the formation of tiny globules, laminated in structure, from the centre outward ; these globules when in contact coalesced to form single laminge in larger masses. In the laminated structure of the larger masses, formed by the coales- cence of the tiny globules into single laminae one upon another, Eainey claimed to find the explanation of the development of shells, bones, and teeth. A precipitate of calcium carbonate alone in gelatin was at first mem- branous, but ra]3idly passed into the globular and crystalline forms, while a j)recipitate of calcium i3hosj)hate alone became at once crystalline, with- out passing through any colloid stage, but a precipitate of the bicarbonates and phosphates retained for an indefinite period the colloid form. This is interesting from the fact that in calcified tissues like bone, dentin, and enamel, the carbonates and phosphates are invariably found associated together. Professor Harting discovered that the calcospherite is composed of a 36 OPERATIVE DENTISTRY. "profoundly modified albumin," which he termed calcoglobulin, and in which the calcium salts are held in some form of chemical combination. The calcoglobulin, which is the matrix of the calcospherite, is exceedingly resistant to the action of acids, alkalies, and boiling water, and is callable of maintaining its form and structure even after the greater portion of the calcium has been removed. Tomes, in commenting upon the character of calcoglobulin, says, " It is a very suggestive fact that in the investigation of calcification we con- stantly meet with structures remarkable for their indestructibility ; for example, if we destroy the dentin by the action of very strong acids or by variously contrived processes of decalcification, putrefaction, etc., there remains behind a tangled mass of tubes (Fig. 130), the '^dentinal sheaths" of ]^eumaun, which are really the immediate walls of the dentinal tubes. Or if bone be disintegrated by certain methods, there remain behind large tubes, found to be the linings of the Haversian canals (Kdlliker), and small rounded bodies recognizable as isolated lacunae f and in the cuti- cula dentis — Nasmyth's membrane — we have another excellent example of this peculiarly indestructible tissue. In x^oint of fact, as will be better seen after the development of the dental tissue has been more fully described, on the borderland of calcifica- tion, between the completed fully calcified tissue and the formative matrix as yet not fully impregnated with lime, there very constantly exists a stratum of tissue which in its physical and chemical properties very much resembles calcoglobulin. It would seem, therefore, that the indestructible organic matrix of bone, cementum, dentin, and the cuticula dentis was in all probability com- posed of this " profoundly modified" albumin, '^calcoglobulin." Hoppe-Seyler believes the calcium salt which chiefly enters into the hardening process in the calcification of. bone, dentin, and enamel, is a double salt of carbonate and jphosphate, one equivalent of calcium carbo- nate combined with three equivalents of calcium phosphate. ENAMEL. Definition. — Enamel is a vitreous, hyaline substance^ covering the entire crown of the tooth in varying thickness, and composed chiefly of phosphate and carbonate of calcium. Fig. 131. Fig. 132. Section of enamel at right angles to the course Three enamel-columns, exhibiting the six- of its columns, exhibiting the six-sided character sided prismatic and waving or ovaricose char- of the latter ; highly magnified. acter ; highly magnified. Histologically, enamel is composed of numerous minute hexagonal prisms (Fig. 131), measuring in transverse diameter from 0.0034 to 0.0015 millimetre and in length from three to five millimetres (Frey), and having Fig. 130. — Dentinal sheaths, the residue which remains after rlecaleification of dentin with strong acids. >( 70. Blood- vessel Pig. 13.3. — Section of developing human molar. Enamel teased from the dentin, and showing ends of enamel-rods. X 1000. Fig. 134.—^, transverse section of enamel-rods; B, longitudinal section of enamel-rods: C, odontoblasts, showing processes ; D, odontoblasts, fcetal kitten ; E, dentin, showing interglobular spaces ; F. dentin, showing laminated structure. (After Stowell.) Fig. 135. — Vertical section of enamel-rods, showing their varicosities. X 350. PLATE I. Showing varicosed enamel-rod?. (After Dr. J. Leon Williams.) Showing raricosed enamel-rods more highly magnified. (After Dr. J. Leon Williams.) PLATE II. Showing varicosed enamel-rods very highly magnified. (After Dr. J. Leon Williams.) HISTOLOGY OF THE DENTAL TISSUES. 37 a common direction at right angles to the surface of the dentin upon which they rest. These prisms are known as enamel-prisms, enamel-rods, or enamel-col- umns. As a rule, the rods are continuous from the dentin to the outer surface, and with the exception of numerous varicosities, are the same size throughout their entire length ; they are not perfectly straight, however, but have a wave-like or spiral course (Fig. 132). At the outer surface, and particularly at the angles of the crown, numerous short rods are found, which extend only a little distance from the surface, and fill in the inter- spaces between the longer rods caused by the increase in the circumfer- ence of the outer surface and the turning of the angles. A section of enamel viewed from the ends of the rods or prisms has the appearance of a finely tessellated pavement (Fig. 133). The rods are hex- agonal in outline (Fig. 134, A), and are separated from each other by an interprismatic substance, the nature of which has formed a subject for much discussion (Fig. 134, B). The individual enamel-rods appear under the higher powers of the microscoi)e to be regularly varicosed, the varicosities not interdigitating as formerly taught, but opposite each other, and the interspaces filled with the interprismatic substance (Fig. 135). Transverse Striations. — With the exception of faint transverse stria- tions, the enamel-rods seem to be structureless. Hertz claimed this appear- ance was due to intermittent calcification of the enamel-rods. Kolliker and Waldeyer believed the striations were due to the varicosities of the individual fi»bres. Bodecker declares that normal, fully developed enamel is non-striated, and von Bbner holds the same opinion, and claims that this appearance of transverse striations is due to the method of preparing the specimens, which are usually mounted in Canada balsam, and as a result suffer from a slight acid reaction sufficient to produce the striated api)ear- ance. Sudduth and Febiger hold to the opinion of Kolliker and Waldeyer, that the striations are due to the varicosities. Williams also maintains the same opinion, and in his recent investigations denies the statements made by Hertz, Bodecker, and von Ebner, and claims that while in some specimens the varicosities are dimly apparent in some parts, they are decided in others, but that they are always present. It has also been stated that each vari- cosity represents a calcified ameloblast, but Williams claims that he has counted fifteen such varicosities within the length of a single ameloblast, and that he has never found less than eight to each cell. The varicosities he believes to be due to the globular form of the individual enamel-globules which build up the enamel-rods. (See Plates I. and II. ) Brown Striae of Retzius. — With low powers of the microscope an- other and larger form of striation is visible, consisting of brownish lines (Fig. 136), the '^ brown strite of Eetzius." They are seen in broad lines, nearly or quite laarallel with the outer surface of the enamel. Tomes suggests that inasmuch as they coincide with what was at one time the outer surface of the enamel cusp, they are in some sense marks of its stratification in its primary deposit. Williams is of the opinion that they are due to a real pigmentation. 38 OPEEATIVE DENTISTRY. Lines of Schreger. — Another class of markings upon the surface of sections of enamel are known as the ^Hines of Schreger." These lines are invisible by transmitted light ; but with reflected light are plainly seen. They are well defined at the point nearest the dentin, but become gradually less marked as the outer surface of the enamel is reached ; irregularly formed lines extending in a longitudinal direction with the enamel-rods are sometimes seen in the enamel near the surface of the dentin. They have the appearance of open spaces or cavities, and are sometimes in communi- cation with the dentinal tubes. Cracks and fissures are often seen upon the surface of the enamel, but these have no special significance except as they may be predisposing causes of dental caries. Nasmyth's Membrane. — Covering the enamel of young, newly eru]3ted teeth is a thin membrane, the cuticula dentis, or ]^asmy th' s mem- brane. This membrane is thought to be formed from the outer layer or tunic of the enamel-organ, and measures in thickness from 0.001 to 0.0013 millimetre. It is exceedingly resistant to the strongest acids, alkalies, boiling, and maceration, but is soon worn from the teeth by the friction of mastication. It yields no gluten. (KoUiker). Chemic Composition of Enamel. — Enamel is the hardest structure of the body, and at the same time, by the arrangement and character of its component parts is capable of great resistance to mechanical force and the attrition due to the mastication of food. It is almost if not entirely destitute of organic matter, and possesses no nutritive canals. Von Bibra gives two analyses of enamel, the first from an adult man, the second from an adult woman. 1. 2. Man. Woman. Calcium phosphate and fluoride 89.82 81.63 Calcium carbonate 4.37 8.88 Magnesium phosphate 1.34 2.55 Other salts ,. 0.88 0.97 Cartilage ■• • ■ 3.39 5.97 Fat 0.20 a trace 100.00 100.00 Organic matter 3.59 5.97 Inorganic matter , 96.41 94.03 100.00 100.00 Williams says, " Enamel is a solid mineral substance, and the finest lenses reveal not the slightest difference between enamel ground moist from the living tooth and that which has lain in the earth for a hundred centuries;" and also, that '' mature, completely calcified enamel contains no trace of organic matter, therefore no physiologic change is possible in completely formed enamel." The chemic analyses which have been published from time to time have estimated the organic material in the enamel of a human adult tooth at from two to seven per cent. The organic material in these analyses was estimated simi^ly by loss of weight on ignition. This is evidently the source of error, for no account is made of water being a constituent of dried enamel. C. Tomes found that after drying elephant's enamel for a Striation '^,' ■•^,»;'' Crack in the enamel Striation Crack in tlie enamel \ \\i J^wBm^ Dentin Fig. 136. — Section of enamel, showing the brown striations of Retzius. (V. A. Latham.) X HO. Ameloblastic layer and ameloblastic processes Stellate reticulum Forminff dentin ^ - \ 4 Dental papillee r^G. 137. — Transverse section of dental follicle, showing first layer of ameloblasts. (V. A. Latham.) X 325. Fig. 138. — Teased section of developing human molar, showing the ameloblasts. (V. A. Latham.) ;< 1000. ♦ /| Fig. 139. — Developing enamel, showing Tomes's processes at A. (R. R. Andrews.) Formina- ameloblasts Stellate reticulum Fig. 140.— Section of developing human molar, showing the relations of the various stractures. {Y. A. Latham.) X 1000. Formed dentin Odontoblasts Stratum intermedium Ameloblasts Pulp Fig. 141.— Section of developing human tooth, showing ameloblasts highly magnified. (Zeiss one-twelfth oil immersion.) Fig. 142. — Section of developing tooth, showing ameloblasts more highly magnified. St( llatc reticulum Outer ameloblastic membrane Inner ameloblastic membrane , Stratum intermedium I'^ormed ameloblasts Formed enamel Formed dentin Odontoblasts \>.« ' •' Fig. 143.— Transverse section of developing tooth, showing the arrangement of the tissues. (After Andrews.) X 275. HISTOLOGY OF THE DENTAL TISSUES. 39 long time at a temperature of 300° F. that it still contained about four per cent, of water. In decalcifying sections of fully formed enamel by the aid of acids, it is found that the interprismatic substance is first attacked, and the rods fall apart, which proves conclusively that the interprismatic substance is a calcium cement material, more readily acted upon than the rods them- selves. If the process of decalcification is continued, the enamel-rods are attacked, and the whole structure is destroyed, leaving behind no evidence of an organic matrix. CALCIFICATION OF ENAMEL, Amelification is the process by which the calcium salts are deposited within the matrix constructed by the ameloblasts for the formation of enamel. As previously stated, the process of calcification first begins in the dentin paiyiUaj by the formation of a layer of dentin at those points which are denominated the lobes of the morsal edge and the cusps of the morsal surface. Upon this layer of dentin, which is as yet only partially calcified, the first layer of ameloblasts is arranged (Fig. 137). These cells are some- what in the form of columnar epithelial cells, have oval nuclei and taper- ing processes projecting from their inner ends, — Tomes's processes (Figs. 138 and 139), The ameloblasts Stand close together, with one end resting upon the newly formed dentin, and the other in contact with the stratum intermedium, and this again in contact with the stellate reticulum (Fig. 140). This is further and more beautifully shown in Fig. 141. In this illustration the ameloblasts are seen resting upon the formed enamel, while the opposite ends are in contact with the stratum intermedium. Fig. 142 is a higher magnification of the same section. Stratum Intermedium. — In the earlier stage of enamel formation, various observers have described the presence of what has appeared to be a structureless membrane lying between the odontoblasts and the first layer of ameloblasts, and another between this layer of ameloblasts and the stratum intermedium, the formation and character of which has not been demonstrated (Fig. 143). Williams has designated these layers by the terms inner and outer ameloblastic membranes, and describes them as being composed of a finely fibrous structure. The outer layer or membrane is particularly interesting from the fact that it seems to be composed of two sets of fibres running in nearly opposite directions, but neither direction corresponding with the long axis of the ameloblasts. One set of these fibres passes in a somewhat more oblique course than the others, and becomes confiuent with the ends of the enamel-prisms, while the other set sweep downward in a circular course, crossing the more oblique-running fibres and the enamel-prisms nearly at right angles. Mummery has beautifully shown the interlacing of these fibres. Sometimes both sets of fibres join and twist about each other in a rope-like design, and pass along the course of the enamel-prisms. A third 40 OPERATIVE DEKTISTRY, set of fibres may sometimes be seen running parallel to the ends of the ameloblasts. These fibres, he thinks, are identical with the j)lasm-strings first discovered by Andrews, which are often visible in the ameloblasts. With a magnifying power of from one thousand to two thousand three hundred diameters, he discovered the inner and outer ameloblastic mem- branes to be composed of several layers of protoplasmic strings or fibres. These processes or strings are often seen to emerge from the inner ends of the ameloblasts, and turn to the right and left. He thinks it quite possible that the structures, which he has designated as the in7ier and outer amelo- blastic membranes, are formed by the accumulation of the calcific albuminous product of the stratum intermedium within the meshes of these plasm- strings, which spread out on both ends of the ameloblasts, forming a struc- ture resembling a membrane (Fig. 144,) Blood-Supply of the Enamel-Organ. — Wedl, Magitot, Tomes, Sud- duth, Andrews, and others have stated that they have uniformly failed to detect blood-vessels in any part of the enamel- organ. A reference to Fig. 145 will show the enamel-organ to be abundantly supplied with blood- vessels, which cover its entire outer surface. But Williams has shown conclusively in recent papers published in the Dental Cosmos for 1896 and 1897, accomiDanied by numerous most excellent photo-micrographs, that not only are blood-vessels seen within the enamel-organ, but that they are found within the stratum intermedium in an intricate plexus. The ameloblasts are surmounted by epithelial" papillae, which Williams terms ''secreting papillse" (Figs. 146 and 147), and these are surrounded by a free distribution of cai^illary loops. The ameloblasts seem to be con- nected with the papillsB by root-like processes, which are lost in the sub- stance of the j)apilla to which they belong. The papillae (Figs. 148 and 149) are from five to six times as large as the ameloblasts, and may therefore supply from twenty to twenty-five ameloblasts. These he believes to be secreting organs. He further states that, although the stratum intermedium in forming human enamel is not very striking in its resemblance to glandular tissue, aside from the arrangement of its blood-vessels, that nevertheless in studies of the evolution of the enamel-organ of the mouse and rat its place among glandular structures at once becomes evident. He also states as his opinion that the function of the stratum intermedium is undoubtedly to select from the blood brought to it by its capillary vessels the necessary material for the construction of the enamel. He explains the difficulty in the theory of the formation of enamel before the development of the stratum intermedium, by suggesting that the material necessary for the com- mencement of enamel formation is stored u/p in the stellate reticulum of the enamel- organ. Charles Tomes does not agree with Williams in his conclusions in refer- ence to the presence of blood-vessels in the stratum intermedium or in the supposed secreting function of the papillae of the stratum intermedium. Spee and Andrews have taught that the process of calcification of the enamel was due to the deposition of "droplets" or spherules of calco- globulin formed within the ameloblastic cells, and excreted or shed out stellate reticulum ^> Masses of - calcoglobulin in calcifyiiia amelobiasts Stellate reticulum Outer ameloblastic membrane Inner ameloblastic membrane Stratum intermedium Calcifying enamel Dentin Fig. 144.— Developing tooth of embryo lamb. (After Andrews.) X 105. Capillary blood-vessels Forming enamel Enamei-organ Dental pulp Blood-vessel, arising from base of dental papilla Formed enamel Formed dentin Blood-vessel, arising from base of dental papilla Bone Fig. 145.— Vertical section of central incisor of human foetus (injected), showing blood-supply of enamel- organ. (V. A. Latham.) Papillary layer ameloblasts lyina; beneath Formed enamel Formed dentin Fig. 146. — Transverse section of dental follicle of rat, showing papillary layer. (Y. A. Latham.) X 90. Capillary blood-vessel Fig. 147. — Section of forming enamel from jaw of rat, showing enamel papillae, blood-vessels, and fibrillse. (V. A. Latham.) X 325. Fig. 148.— Section of incisor of a rat. (J. Leon Williams.) X 80. A, capillary loops torn out of secreting papillse ; B, secreting papillae after removal of capillary loops ; C, ameloblasts ; D, enamel ; £, dentin. Spherules of calcoglobulin Fig. 149. — Ground section of developing tooth of rat, showing secreting papillas of Williams. (Von Koch method.) (V. A. Latham.) X 97. Fig. 150.— Forming enamel. (R. R. Andrews.) A, globular bodies of calcoglobulin forming enamel-rods. Fig. 151. — Section of forming enamel, slmwing nucleus of ameloblasts and calcospherites forming the enamel-rods. (R. R. Andrews.) HISTOLOGY OF THE DENTAL TISSUES, 41 (Kolliker) "by them at the extremities nearest to the odontoblastic laj^er to form or build up the individual enamel-rods, the fibres of Andrews, acting as a sort of reticulum or scaffolding to determine their arrangement. Williams states that the "albumin-like substance secreted from the blood-vessels by the cells of the stratum intermedium" is absorbed by the ameloblasts and deposited by them in globular masses, which he terms " enamel-globules," to form the enamel-rods (Fig. 150). He thinks these ^'globular masses of spongioplasm" are successively formed within the ameloblasts themselves. "The cytoplasm of the amel- oblasts has a fairly uniform structure, which consists of a number of globular masses of spongioplasm of the same diameter as the cell, and united longitudinally by somewhat coarser plasm -strings, the fibres of Andrews. He says further, ' ' there are many indications that these ' enamel-glob- ules' are formed by the nucleus of the ameloblast, and they appear to pass down the cell by the natural process of growth as new ones are formed above, to be finally shed off the inner ends of the cells onto the surface of the forming enamel, where they become completely infiltrated with the albumin-like lime-conveying substance and calcified" (Fig. 151). The "enamel-globules," which are uniform in size (Fig. 152), are, according to Williams, quite distinct from the more transparent and irregularly sized masses of calcoglobulin, and that the enamel-rods are built up by the successive, rhythmical, orderly deposit of these "enamel- globules, ' ' while the larger and more irregular-sized bodies of calcoglobulin melt and flow together to form the interprismatic substance. The elder and younger Tomes both held the theory that the cell- wall of the ameloblasts may be calcified to form the interprismatic substance, while the cell-contents solidify into the enamel-rods proper. Heitzmann and Bodecker promulgated the theory that the interpris- matic substance was composed of a reticulum of living matter, and that enamel formation was due to the breaking up of the ameloblasts into "em- bryonal corpuscles," which afterwards become calcified to form the enamel- rods. This theory for a time dominated the minds of a verj^ large propor- tion of American dentists, influencing their practice accordingly. This view taught that physiologic changes took i)lace from time to time in the structure of the enamel through its reticulum of living matter. Later investigations have demonstrated the fact that these authors were mistaken in their conclusions, and as a result the theory has to-day few advocates. DENTIN. The dentin is an organic calcified tissue, non-vascular, less dense than enamel, and harder than bone, which it somewhat resembles. It forms the central portion and greater bulk of the hard structures of a tooth, com- pletely investing the pul^) from which it is generated ; it is covered and protected at the crown by a layer of enamel, while the root is encased with a layer of cementum (Figs. 153 and 151.) If the enamel and cementum should be removed, the dentin would still retain the general form and characteristic features of the tooth. 42 OPERATIVE DENTISTRY. The dentin is a dense, liiglily elastic substance, white or yellowish- white in color, and to some extent translucent. Vascular canals are occasionally seen in human dentin, but they are to be considered as abnormal conditions. The dentin consists of an organic matrix strongly impregnated with the calcium salts. The Matrix. — The matrix of fully formed dentin appears to be struc- tureless, although there are instances in which there are indications that at some time during the development of the dentin connective-tissue fibres were present (Mummery). The' proportions of the organic and inorganic constituents are so varia- ble that no chemic analysis could be considered other than approxi- mating the exact amounts in even the same individual, as the relative quantities are constantly changing from childhood to old age. The rela- tive i^roportions are also very variable in different individuals. Von Bibra gives the following analysis of perfectly dried dentin, the first an adult man and the second a woman twenty-five years old : 1. 2. Man. Woman. Organic matter (tooth cartilage) 27.61 20.42 Fat 0.40 0.58 Phosphate and fluoride of calcium 66.72 67.54 Carbonate of calcium. 3.36 7.97 Phosphate of magnesium 1.08 2.49 Other salts. 0.83 1.00 100.00 100.00 Galippe gives the relative proportions of organic and inorganic matter in dentin as follows : Water and organic matter 25.29 Mineral matter 74. 71 100.00 Mineral Matter. Soluble ash (alkaline chlorides and phosphates) 0.54 Calcium carbonate - 0.35 Magnesium carbonate 1.13 Calcium 45.11 ' Magnesium 1.67 Phosphoric acid 23. 70 Silicates 0.04 Undetermined 1.30 Black, in his experiments upon the ' ' Physical Characters of the Human Teeth," Dental Cosmos, 1895, found the analysis of the dentin of two hun- dred and sixty-eight teeth taken from one hundred and eleven different persons to giv^e the following results : Average age of the individuals from whom the teeth were taken was, in years 32.33 Specific gravity of the dentin 20.92 Percentage of water 11.06 Percentage of lime salts 63.54 Percentage of organic matter 25.36 Fig. 152. — Section of forming enamel, calcoglobulin spherites being deposited to form the enamel-rods, (R. R. Andrews.) Knamel Dentin Pulp-cavity ,-V r" ■ • fe \] ",. / '^ U. .i^-'-: Mi > '; ■:h Ifi iia'^ M'liiB ^- k"' w ^^ Cementum Fig. 153 —Longitudinal section of an incisor. (After Stowell.) Fig. 154. — Longitudinal section of an inferior molar. ( After Stowell . ) Pulp-canal Dentinal tubuli Cementum Secondary dentin Fig. 155. — Transverse section of root of human bicuspid, showing radiation of the dentinal tubuli. Fig. 156.— Normal dentin at dento-enamel junction, showing dentinal tubuli. (F. B. Noyes.) X 760. HISTOLOGY OF THE DENTAL TISSUES. 43 The Dentinal Tubuli. — The matrix is everywhere permeated by a system of parallel caualiculi or tubuli, the dentinal tiibuU, which radiate from the pulp-cavity towards the outer surface of the dentin (Fig. 155). The diameter of the tubuli is from 0.0011 to 0.0023 millimetre and up- ward (Frey). (Plate III.) The dentinal tubules are similar to the caualiculi of bone in that they are provided with a special lining layer or sheath, the dentinal sheath of Neumann. In following the course of the dentinal tubuli, it will be noticed that they do not form a straight line in their passage from the iDulp-canal to the surface of the dentin, but that they describe two, more often three, undu- lating curves, and within these many very small, more or less angular or spiral bends, of which about two hundred may be counted in the length of a line (Fig. 156). (Eetzius. ) It is further observed that like the caualiculi of bone the dentinal tubuli give off numerous branches in their course which unite with neighboring tubuli and with each other (Fig. 157). As the tubuli approach the sur- FiG. 157. Section of root, parallel to dentinal canals, (.\fter .stowell.) face the division is more rapid, and the size of the branches is correspond- ingly decreased. At the external surface of the dentin many of the tubules unite by anastomosis (Fig. 158), others terminate in the granular layer of Purkinje and Tomes,- while a third set penetrates the cementum and may unite with its lacunae through their caualiculi ; or enter the enamel by means of the open spaces, or interstices between the enamel- FiG. 158. 1, tubuli of dentin ; 2, enamel. rods, already referred to as existing in that portion of the enamel next to the dentin (Fig. 159). This system of canals terminates, or rather has its beginning, in free openings upon the internal surface of the pulx^-canal. 44 OPERATIVE DENTISTRY. Fig. 160, which is highly magnified, shows the dentinal fibrillee crossing from the dentin to the enamel and apparently passing between the enamel rods. The Dentinal Sheaths. — The dentinal sheaths, or walls of thetubuli, as they are termed, are composed of a singularly indestructible substance, which is peculiarly resistant to the action of acids, boiling in caustic alka- lies, or to putrefaction ; caries does not destroy them, and they can also be demonstrated in fossil teeth; this substance is in all probability "cal co- globulin." Keumann and Henle are of the opinion that the dentinal sheaths are calcified. The existence of the dentinal sheaths can be demonstrated by decalifying the dentin with strong acids. This process requires several days for its accomplishment. The residue is found to be composed of a tangled mass of a fibrous-appearing material (Fig. 161) which upon care- ful examination is found to be composed of the dentinal sheaths. Magitot and Sudduth are of the opinion that the dentinal sheaths do not exist as structures distinct from the fibrils. Eose demonstrated the presence of the sheaths of Neumann by Golgi's rai^id method of staining with nitrate of silver. If the tooth is previously prepared by Weil' s method, the soft parts, including the dentinal fibrils, do not take the stain, so that in transverse section the fibril is seen as a bright point in the centre of the black dentinal sheath. (Plate III.) Tomes is inclined to the belief that the dentinal tubuli possess definite lining walls ; but yet suggests that it is possible that their seeming exist- ence may be the result of the action of the agents used in the preparation of the specimen. He also calls attention to the fact that that part of the matrix immediately embracing the fibrils differs in chemic constituents from that which makes up the bulk of the matrix. Dentinal Fibrils.— The dentinal tubules (Plate IV.) are occupied for their entire length by solid fibrillse or processes given off from the odonto- blasts, which are known as Tomes^ s fibrils, or the dentinal fibrils, the function of which, it is supposed, is to transmit sensation and possibly nutritive fluid from the plasma of the blood. These questions, however, have never been satisfactorily settled. The fibrils of Tomes are solid structures which fill the lumina of the dentinal sheaths, so that it would seem impossible for them to carry fluid except by a process of osmosis. Histologists have not been able to determine the real nature of the fibrils, though there is no doubt from the clinical stand-point that they carry sensation. Some writers have asserted that the terminal nerve-fibres of the pulp pass between the odontoblasts, and either unite with the dentinal fibrils or accompany them into the dentinal tubuli. Others are of the opinion that the non-medullated fibres of the pulp become united with the stellate layers of cells which lie beneath and are connected with the odontoblasts, and that thus the power of carrying sensitive impressions is conveyed to the dentinal fibrils ; while still others have thought that the sensitiveness of the dentin was due to the transmission of vibrations to the pulp, through a fluid contained in the tubules, or some other inert conductor. Boll (1868) was the first investigator to make authentic observations in PLATE III. .. ^ ^ # # -..^ ifi '^ A '' ^ ■ <* ^ k\ f , ^ ,^ A if^ « " " • * 1 '. '^ « ,j" : i i' •r«*» 'I k * H # m i • • f ^•\ #^ »■•■* »^ ^ n ^ « # ■^^. Normal dentin showing tubuli in cross section. (F. B. Noyes.) Highly magnified. PLATE IV. Normal dentin showing tubuli in longitudinal section. (F. B. Noyes.) Highly magnified. Dentinal tubuli entering the enamel Dentin Fig. 159.-Sectiou of dentin and enamel, showing tubuli entering the enamel. (V Ameloblasts (V. A. Latham.) Formed enamel Fig. 160.— Vertical section of developing h Odonto- blasta Blood- vessei. umau UM,ili, slL.winjf dentinal fibres passing from the dentin to the enamel. >( 1000. Fig. 161.— Dentinal sheaths isolated by decalcification of the dentin. X 273. Enamel Interglobular Interglobular b paces Dentin Fig. 162.— Vertical section of enamel and dentin, showing interglobular spaces. X 50. HISTOLOGY OF THE DENTAL TISSUES. 45 the endings of the nerves of the pulp. His observations were made upon the pulps of the canine teeth of young rabbits and guinea-pigs, some of which were stained with gold chloride ; others were fixed for a short time in dilute chromic acid solution, teased out and mounted in this solution. With the gold-chloride method the results were negative. The chromic acid method enabled him to make out numerous medullated and non- medullated nerve-fibres in the tooth-pulp. Lying beneath the odonto- blastic layer was an especially dense net-work of non-medullated ^erve- fibres. From this net- work he discovered fine fibrillae passing between the odontoblasts, some of which could be traced for a considerable distance beyond. He did not, however, succeed in tracing these fibrillte into the dentinal tubules, but he felt sure, although unable to demonstrate it, that they did enter the tubules, and he assumes there are two kinds of tubules in the dentin, those which carry the dentinal fibrils and those which carry the nerve-fibrils. Underwood and Mummery have demonstrated by the gold-chloride method the presence of nerve-fibres arising from the deeper portions of the pulp which run directly to the dentin, and appeared as though they entered it, thus far confirming the observations of Boll. Tomes says, the dentinal ''fibrils are not nerves in the ordinary sense, and were never supposed to be ; but there are many examples of cellular structures which are connected with the termination of sensory nerve-fibres, such as the goblet-cells in the olfactory membrane of the frog, and it is quite possible that the odontoblasts may stand in some such relation to the nerves of the pulp, the terminations of which have even not yet been satisfactorily traced." Mummery found later that by following Boll's method of preparation, by Weil's process, and also by decalcification processes, that he could trace a great number of fibres which pass from the pulp to the dentin, these fibres being much smaller than the dentinal fibrillse. He was not, however, able to see what became of them after they reached the dentin. By means of various stains, especially iron, followed by tannin, he was able to show them stained, and they appear to be trace- able backward into nerve-trunks a little below the surface ; these trunks consisted of bundles of non-medullated nerve-fibres, in fact, axis-cylinders. He believes the dentin is permeated by dentinal fibres and also by much finer fibres, some of which run up towards it from fusiform cells which lie near the surface of the pulp, while others appear to come from points deeper down in the pulp, and to be devoid of fusiform enlargements. Charters White is of the opinion that these fibres, after they leave the bases of the germinal corpuscles, enter the fibrous tissue of the pulp and become fused in the outer coat of the nerve, but that as yet these facts have not been positively demonstrated. Coleman compares the odontoblasts to tactile corpuscles. Pacinian bodies, the rods and cones of the retina, and the termination of the audi- tory nerves in the cochlea. He believes that a connection exists between the odontoblasts and the nerve-fibres, but does not consider it as absolutely necessary to make out such a connection between the nerve-fibres and the 46 OPERATIVE DENTISTRY. sensitive part. He says, " The impression received by the long processes of the odontoblasts might be conducted from these bodies through numer- ous cells which intervene between them and the nerve-fibres, or possibly the connective tissue of the pulp may perform this office." Magitot speaks very positively of the terminal fibrils of the nerves of the pulp being continuous with a layer of reticulate cells, which lie imme- diately beneath the odontoblasts, and that these communicate freely with the processes of the odontoblasts, so that there is a very direct communica- tion between the nerves of the pulp and the dentinal fibrils. Sudduth has never been able to demonstrate any connection between the terminal nerve-fibres of the pulp and the odontoblasts. Klein maintains that the only funiction of the odontoblasts is to form the dentin matrix, and that the dentinal fibrils are long processes given off from the dee^Dcr cells of the dentinal papilla, and that they run up between the odontoblasts and enter the dentinal canaliculi. Eobertson found, in examining sections of the tooth-pulp of the ox which were i^repared by fixing and teasing in osmic acid, that the axis- cylinders of the meduUated nerve-fibres lose their medullary sheaths, and after extending for a greater or less distance, become continuous with the pulp iDrocesses of the odontoblasts, which, therefore, with their dentinal processes may be considered as nerve- end organs. Bodecker says, "In specimens of nine-month foetal pulps, sufficiently stained with gold chloride, I have observed that the medullated nerve- fibres upon approaching the periphery of the pulp are destitute of their myelin sheath, and now become bare axis- cylinders, split up into numer- ous extremely delicate beaded fibrillse, the axis-fibrillae. " Dentz made sections from embryos in which about one-half of the dentin was formed, and discovered pear-shaped bodies arranged with great regularity a short distance within the border of the dentin, the small ends being directed towards the pulp and connected by the small ends with one or more dentinal tubes. Each of these pear-shaped bodies had two or three nuclei, and upon the whole quite closely resemble certain forms of nerve-end organs. Eetzius demonstrated (1895), by the aid of Golgi's method of staining sections from the teeth of rats, that the nerves of the pulp resolve them- selves into fine varicosed fibrils, which extend through a layer of odonto- blasts as far as the dentin, but did not x)enetrate into the latter. Huber found by the use of the intravenous methylene-blue method of Ehrlich, — injection of a methylene-blue normal salt solution into the ves- sels of a narcotized animal which x^roduces a stain of the peripheral nerves, — in which a one per cent, of methylene-blue normal salt solution was used, was injected into the carotid artery of a rabbit immediately after killing it with chloroform. Thirty minutes later the jaw was removed, broken open, and the teeth removed, care being taken not to injure the x)ulps. The pulps were then removed and placed at once upon a slide moistened with a normal salt solution. Such freshly prepared specimens showed the axis- cylinders of the pulp- nerves stained with the characteristic blue color, the other tissues not at HISTOLOGY OF THE DENTAL TISSUES. 47 all or only faintly blue. Sucli specimens must he fixed at once, as the color will otherwise fade very quickly. As fixatives, Huber used a satu- rated solution of ammonium picrate, or a solution of ammonium molyb- date. The former was mounted in a mixture of glycerol and the ammo- nium picrate solution, the latter dehydrated and mounted in balsam. By these methods the tissues of the pulp become very clear. In examining the terminal branches of the medullated nerve-fibres of the tooth-pulp, he found that on approaching the surface of the pulj) they lose their medullary sheath, and the non-medullated terminal branches, after repeated division, form a plexus immediately beneath the odontoblasts. The non-medullated terminal branches are often beset with nuclei ; they branch and rebranch into long, delicate varicose fibres which may often be followed for long distances. This accords with the observations of Eetzius with the Golgi method. Huber found as did Eetzius, "that terminal fibrils given off from the plexus of a varicose fibre found under the odontoblasts pass uj) between the cells, to terminate usually in fine granules near the free end of the odonto- blasts. Xow and then some small fibril may be traced as it takes a tangen- tial course over the free ends of the odontoblasts, as was found hy Eetzius." These observations, he thinks, taken with those of Eetzius, ''warrant the statement that the terminal branches of the i)ulp-nerves end between the odontoblasts near their free surface, occasionally between these cells and the dentin, and that they do not make any connection with the odonto- blasts nor with any of the cellular elements of the x)ulp." He was never able to trace any nerve-fibril beyond the odontoblastic layer. Interglobular Spaces. — The " interglobular spaces of Czermack" are a system of irregular cavities of extreme variableness in size, which exist normally in the dentin, and are the interstices or sj^aces between the rounded projections of numerous spheroidal or rounded bodies or masses grouped together within the basis substance of this tissue, and designated as dentin glohides (Figs. 162 and 163). They are found principally at the union of the dentin with the cementum, where they are small and very numerous, forming what is generally known as the "granular layer of Tomes" (Fig. 164). Many of the dentinal tubuli have their endings in these spaces. The granular layer is also found in that portion of the dentin which lies be- neath the enamel, but in this location it is not so strongly marked. Although the interglobular spaces are most numerous at the periphery of the dentin, they are not confined to this location, but may be found in all parts of this tissue. These spaces, which in dried sections of dentin appear as open spaces, with irregular outlines and sharp -pointed processes, extending in all directions, giving them the appearance of lacunae, are in the fresh state filled with calcoglobulin which has not become fully calcified. Broomell claims they are filled with a soft living plasma, having a structural arrangement similar to the basis substance or matrix of the. dentin. 48 OPERATIVE DENTISTRY. Tomes is inclined to tLe opinion that the larger interglobular si^aces found in the deeper portions of the dentin ought not to be considered as a normal condition, but rather as an indication of an arrested development. The dentinal tubuli are not arrested by the interglobular spaces, but pass through them without interrux)tion in their course. Bodecker claims that the spaces of the granular layer are filled with living plasma, and that through this the soft fibrils within the tubuli are in communication with the soft contents of the lacunae and the canaliculi of the cementum. Incremental Lines. — Certain lines are to be seen, particularly in the crown of the tooth, indicating the laminated structure of the dentin ; these have been called the " contour lines of Owen" and the "incremental lines of Salter" (Fig. 165). They find their explanation in the laminar growth of the dentin, as already indicated. Development of the Root. — The root of the tooth is formed as a result of the progressive lengthening of the pulp (Fig. 166 and Fig. 167) and the continued production of Tomes' s fibres, of the canaliculi and the ground substance or matrix, through the agency of the odontoblasts or other formative cells. The process is the same as that already described in the development of the crown, — viz., the formation of cup-like layers or laminae one within the other. If a forming tooth is examined at that stage in which the crown has been completed, a deep cup-shaped depression will be noticed over the whole radial end of the crown, this being occupied by the formative pulp. The deposition of calcoglobulin begins at the outer circumference of the pulp, building each time a quoit-like layer, with its rim always at the outer circumference of the pulp and its convexity directed towards the crown. As fast as the dentin of the root is formed, it is covered by a deposition of cement material formed by the cementoblasts lying within the developing pericementum or wall of the tooth-follicle. Dentinification. — Calcification of the dentin begins at about the six- teenth week of intrauterine existence by the formation of a tiny cap or layer of calcific material at the tips of the incisors and cuspids (Fig. 168), and about a week later in the cusps of the molars. The process begins upon the surface of the dentinal bulb or papilla, by the formation of layers or laminae, one within the other, the size of the papilla gradually de- creasing as each new lamina is formed until it reaches the size prescribed for it by nature. Some time before the beginning of the process of calcification of the dentin there is a layer of cells developed upon the surface of the papilla, ovoid in form, and having a long process upon the end, which points towards the enamel-organ (Fig. 169). These cells have already been men- tioned, and were termed by Waldeyer the odontoUasts or dentin-building cells. This layer of cells constitutes the memhrana eboris of the older writers. The form of the odontoblasts varies considerably at dififerent periods of the evolution of the dentin. In the early stage, just prior to the commence- ment of the process of calcification, the cells are generally ovoid and have Enamel Dentin Fig. 163. — Vertical section of enamel and dentin, showing interglobular spaces, y^ 110. Lacunae 1 ^^=^>rfs- ^ ^ > «. "* t •_ -Vs- ir-*"« -^ V \ ^. * J ■^ r ^ ' •. my^" r *■ ^ Dentin ' Interglobular •' a spaces, or * " granular layer <'■ ■* i)f Tomes Fig. 164. — Transverse section of dentin and cementum. X 97. Enamel-rods, showing interprismatic substance Incremental ines Fig. 165.— Oblique section of enamel and dentin, showing incremental lines. (V. A. Latham.) X 500. Commencing formation of the root by lengthening of the pul] Commencing formation of tlie root by engtheningof the pulp Fig. 106.— Vertical section of face of human embryo, showing the beginning of the formation of the roots of the teeth. (V. A. Latham.) X 7. Root begiiiniii}< to form Blood-vessels and nerves Blood-vessels and nerves Fig. IG".— Section of human lower jaw, shovi'ing blood-vessels and nerves at base of the tooth-follicle, and the beginning of the formation of the root. (V. A. Latham.) >,; 9. Enamel Dentin Dental papilla I Fig. 168.— Vertical section of developing human cuspid, showing early stage of calcification. (V. A. Latham.) X lUO. Fig. 169. — Teased section of developing human molar, showing the odontohlasts and their processes. (V. A. Latham.) X 1000. ^ Fibril cell Truncated odon- toblasts, showing spherule of calcoglobulin Fig. 170.— Truncated odontoblasts and libril cells. (R. R. Andrews.) HISTOLOGY OF THE DENTAL TISSUES. 49 a sino-le r^rocess but during the active stage of development the cells are LaSCTor truncated at the end directed towards the forming dentin m. 170) During this period the odontoblasts often present two or more processes • Boll has counted no less than six, proceeding from a smg e celL Each cell possesses a single ovoid nucleus, which is located in the end of the cell nearest to the dentinal papilla (Fig. 171). The nucleus is some- times pointed at the extremity nearest the forming f^^^\^- ^ ^h^ l^.^f ^^f^ the ceil is finely granular, and Waldeyer and Boll both found the eel destitute of any semblance of membrane. The processes of the cells pass into the dentinal tubuli, and constitute the dentinal fibrils. Stowell (1887) says there are three separate forms of processes arising from each odontoblast: first, those that unite it to its fellow ; second, those by which it forms its attachment to the connective-tissue cells of the pulp proper ; and third, those that pass into the dentinal tubules, the dentinal fibrils, the latter as they approach the periphery of the dentin branch and finally unite with the cells of the granular layer and the cementoblasts. v^i „„<-<. After the active stage of dentin formation has passed, the odontoblasts again resume their original ovoid form, tapering off to the dentinal process. Several theories, more or less divergent, have from time to time been advanced as to the process by which the dentin was developed the mam point in controversy being the part played by the odontoblasts in this ^"^^Waldeyer, Frey, Boll, Beale, and others support the theory that the dentinal fibrils, the sheaths of I^eumann and the matrix surrounding them, are formed from the odontoblasts by a metamorphosis of these cells, these structures representing three stages in the conversion of the same sub- stance. Beale expresses it as j)rotoplasm-t^e dentinal fibrils ; formed material -the dentinal sheaths ; calcified formed material, -the matrix, the completed, fullv calcified tissue. Yon Ebner has discovered the existence of a delicate fibrillar structure in both bone and dentin, and although von Ebner and Eose both believe that the whole of the dentin is derived from the odontoblasts, they say their axial portions persist as the dentinal fibrils, while their outer portions are metamorphosed into a delicate fibrillar gelatinous tissue, a sort of connec- tive tissue, which forms the matrix and receives the deposition of the lime- Tomes says upon this question, "The close relation of these cells to the dentin, their change in form according as dentin-building was or was not actively «-oing on, their resemblance in position and apparent consist- ence to osteoblasts, and the absence of any other of the large cells which we associate elsewhere with elaboration of special products, would natu- rally lead to the inference that they were the chief factors in the segrega- tion of lime-salts and their incorporation in the dentin." Andrews (1887) called attention to pear-shaped cells, which he termed " deniM. corpuscles,^' lying between the square-end odontoblasts so uniformly present during the active stage of dentin formation (Fig. 172). The odontoblasts he considers as simply matrix formers, having nothing 4 50 OPERATIVE DENTISTRY. whatever to do with the formation of the dentinal fibrils, as they are mem- braneless masses of protoj)lasm, while the pear-shaped cells — '^dentin cor- puscles" — form the dentinal fibrils by the elongation of their processes, and which also possess the important function of nourishing the dentin matrix. Mr. Mummery, in following still farther the investigations of von Ebner, noted the appearance of connective-tissue fibres, or bundles of fibres, just in advance of the main line of calcification, which had not been derived from the odontoblast, but from the connective-tissue cells of the dentin papilla. He discovered further, in young developing teeth, by the aid of Koch's method of preparing sections, as modified by Weil, the i^reseuce of a distinct reticulum of fine connective-tissue fibres, which passed in bun- dles between the odontoblasts and enveloped them. Within this reticulum he believes the calcium salts are deposited for the building of the dentin matrix. He also found other cells than the odontoblasts applied to the connective-tissue fibres, both in man and in fish, which recall the cells attached to the osteogenetic fibres of bone. In view of these discoveries it would seem that the process of calcifica- tion of dentin is more nearly like that of bone than has been previously supposed, and if Mr. Mummery is right, the question very naturally arises as to the actual part taken by the odontoblasts in the formation of the den- tin. It would seem, however, that the fact is fairly well established that the odontoblasts form the dentinal fibrils by the elongation of their pro- cesses, and that they are the active agents in the development of the dental tubuli ; but whether the odontoblasts or the cells of Mummery superintend the elaboration and deposition of the calcific material to form the dentin is a matter of doubt, and further investigation will be necessary before the question can be settled. Andrews, in speaking of the odontoblasts and the jjear-shaped cells described by Mummery, says, ' ' The odontoblasts are masses of protoplasm, without membranes, and are at a certain stage of growth square and abrupt against the matrix. It is an easy matter to find among them, and immedi- ately adjacent, large numbers of pear-shai^ed cells, tapering into the denti- nal fibril. The odontoblasts, when calcification is active, are scarcely more than masses of protoplasm, filled with minute globules. The fibrils which api^ear to come from them are described by Tomes under three divisions, — viz., "pulp, lateral, and dentin processes,^ ^ which originate probably from a fibril-forming cell. These pass through the soft substance of the odonto- blasts (protoplasm), and seem to be a part of them, but in fresh, young sections the so-called processes move in the substance of the odontoblasts by pressure of the cover-glass, and the fibril may be traced to a pear-shaped cell beyond. There will usually be found as many processes going out from the sides and ends of the odontoblasts towards the pulp as there are going into the matrix from the dentin end of the cell. In cross-sections of the odontoblasts, delicate, light spots are seen in the substance, which are x^robably the cut fibres. When the layer of odontoblasts is teased away from the forming dentin, fibrils are seen bridging the gap, apparently off-shoots from the odontoblasts ; but on careful examination there will stellate reticulum Ameloblastic layer Formed enamel Formed dentin Odontoblastic layer Dental papillse Truncated ends of odontoblasts Fig. 171. — Section of tooth-follicle (human), showing the nuclei of the odontoblasts and of the ameloblasts, and the truncated ends of these cells. (V. C. Latham.) X 325. Fig. 172.— Odontoblasts, showing truncated cells and pear-shaped bodies lying between the dentin corpuscles. (R. R. Andrews.) Lacunpe and '^1?^*?^ canaliculi Haversian Fig. 17r).— Bone, showing Haversian system, lacunse, and canaliculi. X 60. V '\ \ ^^^":r^*«> Fig 174 —Transverse section of human femur, mature bone. X bO. HISTOLOGY OF THE DENTAL TISSUES. 51 usually be found a decided line of demarcation across the fibre at tlie point where it meets the square end of the odontoblast. This line seems to show that the fibril was not continuous with the x>rotoplas.m of the cell. Other sections which have been separated by teasing, show odontoblasts having their side masses of protoiDlasm drawn away from the fibril which appar- ently has run through it. Some of this protoplasm is left upon the fibril, giving it a ragged appearance as it passes from a canal in the matrix across to the separated pulp-tissue, bridging the gap. The pear-shaped cell has perhaps a more important function than the odontoblast i^roper. It is to supply the life and nourishment to the whole of the calcified matrix, as the bone-corpuscle within its " lacuna supplies life and nourishment to bone and cementum." One of the strongest arguments, however, in support of the older theory that the odontoblasts elaborate or secrete the calcium salts and superintend the deposition of this material in the formation of the dentin matrix, is the fact that calcosfsherites of different sizes are found in these cells during the active stage of calcification. Eobin and Magitot noted the presence of globular spherical forms — ■ calcospherites — in the young pulps of human teeth. Henle also discovered them in the young tooth-]3ulps of the herbivora, as did also Robin and Magitot. . In the early history of the dentinal papilla, just before the beginning of calcification, numerous globular, glistening bodies — calcospherites — are to be seen in the papilla and within the odontoblasts, but most abundantly upon the surface of the papilla next to the inner tunic of the enamel- organ, just where the first layer of dentin is to be formed. The calcospherites are seen to collect in large numbers at this point, where they arrange themselves in groups and coalesce to form larger glob- ules of calcoglobulin, as already described. These again melt together to form the first layer of dentin, the matrix forming around the processes of the odontoblasts, which recede as each additional layer of dentin is laid down, the processes of the odontoblasts elongating to accommodate the increasing thickness of the dentin matrix. AVhat becomes of the superabundance of odontoblasts resulting from the continual decrease in the size of the dentin papilla during the forma- tion of the dentin is a question that the author does not remember to have seen or heard discussed. It is a well-established fact that, as a rule, cells and tissues which have performed their functions, and for which nature has no further use, either atrophy or disintegrate, are resolved into their original elements, and are then absorbed. This may be the process by which the used-up cells are removed in the formative pulp. But in seek- ing an explanation of the modus operandi by which the tubules of the dentin become branched, it has occurred to the author that certain of the odontoblasts may coalesce from time to time as the decrease in the size of the papilla makes it necessary for their numbers to be lessened, thus form- ing branching dentinal processes around which the dentin matrix is formed, the larger fibril or main trunk representing the persistent odonto- blast, while the branches represent the fibrils of the cells which have been 52 OPERATIVE DENTISTRY. merged into the persisting cell. This would also explain the presence of the odontoblasts having multiple processes which are so common during the active stage of dentin formation. The presence of the transverse processes which seem to unite the odon- toblasts laterally may be explained by the recent discovery of von Ebner and Mummery of a connective-tissue net- work of iibres passing between and surrounding the odontoblasts, and just in advance of the main line of calcification. CEMENTUM. Cementum, or crusta petrosa, is a specialized product of specialized osteoblasts or bone-producing cells, the cementoblasts. Mature cementum, chemically and physically, is very little different from the compact tissue of bone, with the exception that it is generally devoid of Haversian canals. Figs. 173 and 174 show the structure of mature bone. Cementum is the external covering of the roots of the teeth. In many animals it also forms a part of the covering of the crown, being associated with the enamel in separate vertical laminae. The cementum begins at the neck of the tooth, at the free margin of the enamel, in a thin layer (Fig. 175), and gradually increases in thickness towards the a^e:^ of the root (Figs. 176 and 177). In teeth with roots closely associated the cementum often extends from one root to the other, resulting in a firm osseous union. The cementum is thicker in adult life than in childhood, and in aged people it is thicker than in adult life. Black thinks it grows at intervals during the life of the individual. Histologically it is composed of a matrix consisting of a gelatinous sub- stance combined with the salts of lime. Within the matrix are numerous little hollow spaces, the lacunae, filled with protoplasmic substance, and from which branch in all directions many minute processes, the canaliculi ; these often anastomose with neighboring canaliculi and with the inter- granular layer (Fig. 178). The matrix is composed of collagenous fibrils in fine or coarse bundles, combined with calcium salts, and permeated by vascular canals in the thicker portions near the apex of the root. These vascular canals corre- spond to the Haversian canals of bone. Like bone, when boiled it yields gelatin, and when decalcified it retains its form. At times it appears to be structureless ; at others finely granular or interspersed with small globules (Tomes). The matrix is laminated in structure, the incremental lines running parallel to the long axis of the tooth ; but, although the cementum is thin at the cervix and thick at the apex, the number of lamellae is about the same in all parts of the tissue. The lacunas in dried sections are irregular cavities with their long axis corresponding to the long axis of the tooth. The processes are given off most frequently at right angles to the direction of the lamellae, and most abundantly upon that side towards the exterior surface of the root. The size and form of the lacunae in cementum are very variable, while the Fig, 175.— Transverse section of human cuspid, at cervix, x 150. Enamel Dentin I'lilp-cavity Fig. 176.— Longitudinal section of young cuspid. Fig. 177.— Longitudinal section of young molar. Fig. 178.— Transverse section of apex of human molar. X OT Fig. 179. — LougiiLi.liual ^tcLiuu oi lout of tooth and dheoUis, showing tissues of root and alveolus iw situ. (F. B. Noyes.) X SO. D, dentin ; C, C, oementum ; F, fibres passing over edge of process to outer layer of periosteum ; F', fibres passing to bone (Sliarpey's fibres). Alveolar process Cancellus J '•"4- ^ ^\ ' : ' '' '• ^ ■ ■ ^- - ' C'i Sharpey's fibres Pericementum Alveolar process \)iff^ ('ancellus i- > ,> \ ^ / Fig. 180. — Vertical section of human alveolar process and cuspid tooth in silu. (V. A. Lathaai.) X 100. Fig. ISl.— Developing bone from human scapula. (V.A.Latham.) • .')0. HISTOLOGY OF THE DENTAL TISSUES. 53 number and length of their processes are excessive when compared with bone. The lacunae are formed by cementoblasts or nests of cementoblasts, which have been encapsuled during the process of calcification, but which have maintained their individuality. These are sometimes termed cement- corpuscles. 81iarp€y''s fibres are found in the cementum, having the appearance of rods which run through its substance. They are composed of connective- tissue fibres, and form the medium of connection between the alveolo-dental membrane, or pericementum, and the cementum. Figs. 179 and 180 show Sharpey's fibres in the alveolar process. The dentin and the cementum are inseparably connected through the medium of the granular layer of the dentin, the fusion of the two tissues being so complete that the line of union is often difficult or well- nigh impossible to make out. CEMENTIFICATION. According to the common classification adopted by writers upon ossifi- cation, the methods by which bone is formed are stated as follows : 1, in- tracartilaginous or enchondral ; 2, subperiosteal f and 3, intramembranous ; but the essential nature of the process is the same in all. In the intracartilaginous method the bone is first formed or preformed in cartilage (Fig. 181) . In the subperiosteal the bone has not been X3re- formed by the cartilage, but the tissue in which the bone is to be formed is fibrous and vascular ; osteoblasts appear along the bundles of fibres beneath the periosteum, which become calcified, and bone is formed around them (Stedman) by the deposition of calcoglobulin, as already de- scribed. Many of the fibrous bundles persist in the formed bone as Sharpey's fibres, while in the intramembranous form the bone is devel- oped, as in the cranial bones, from a preceding membranous structure. Sudduth adds a fourth, interstitial, a division of the intramembranous group, which he thinks is necessary to explain the method by which the maxillsB are formed. He claims that osteoblasts are found in the embry- onal tissue of the future maxillary bones "before there are any indications of a condensation of the connective tissue into a membrane such as is found when ossification first begins in the skull-cap. A few osteoblasts, inde- pendent of the influence of either membrane or periosteum, arrange them- selves in groups here and there. These groups are the points of ossifica- tion, and from them the process extends as the jaw develops." The bone formed in this manner i^ provisional bone, and is later removed by internal resorption, as is the case with all foetal bone, and replaced by a permanent bone formation. Cementification is a slightly modified form of subperiosteal ossification. "VYe have seen in our study of the origin and development of the teeth that the enamel-organ and the dentin bulb were enclosed within a sac or follicle. Calcification of the enamel and dentin has progressed within this follicle, but the walls of the follicle have taken no part in the process. In the formation of the root the follicle takes an active ]3art by becoming the 54 OPERATIVE DENTISTRY cement organ. The walls of the follicle are composed of two layers. The outer layer is a dense, firm, fibrous structure, while the inner layer is thin, frail, and somewhat transparent ; both are supplied with a rich net- work of blood-vessels. From the outer layer of the follicular wall the alveolo-dental perios- teum, or pericementum, is develoi^ed, while from the inner layer are formed the cementoblasts, which are speedily converted into cementum. The dentin of the root is in most part formed during the passage of the crown from its bony crypt and eruption through the gum. The process of building the root is from the outer circumference towards the centre : the diameter of the root is thus fixed by the outer layer of the dentin, while the increase in length is by extension. The formation of the cementum, like that of the enamel, is from within outward ; the first layer of the cementum being dex^osited upon the outer circumference or periphery of the dentin of the root ; upon this layer is deposited another, and so on until the typal thickness is reached and the cement-tissue is completely formed. The following table by Underwood will be found valuable as a ready reference of the composition of the various calcified dental tissues and their comparison with bone : CHEMICAL COMPOSITION OF THE CALCIFIED TISSUES (APPROXIMATE TABLE). Adult Enamel. Infantile Enamel. Adult Dentin. Adult Cementum. Adult Bone. Organic matter Per cent. 3.50 88.00 4.50 2 00 Per cent. 15.50 75.50 7.00 9 no Per cent. 28.00 64.50 3.50 2.00 1.50 Per cent. 32 00 Per cent. Calcium phosphate 57 00 51 00 Calcium carbonate 7 00 n 50 Calcium fluoride 2 00 2 00 Magnesium phosphate Other salts 1.50 1.50 50 ^a 1.50 . 1.50 .'SO n ?in 100.00 100.00 100.00 100.00 100.00 It will be seen the amount of organic matter varies considerably be- tween infancy and adult life. Galippe (Journal British Dental Association, 1886, p. 361) has a very exhaustive paper on the chemical composition of the teeth. Hoppe-Seyler has found in the enamel of the new-born child as much as 22.29 per cent, of organic matter, 9.71 per cent, in the young pig, and in the fossil rhinoceros 3.16 per cent. Bibra gives two per cent, of organic matter in the adult male and five per cent, in the adult female. js^asmyth's membrane. The origin and function of IS'asmyth's membrane has famished matter for a considerable difierence of opinion and much speculation. Tomes and Magitot regard it as a thin covering of cementum, as it is similar to and continuous with the cementum covering the root, lacunae being foand in its substance. Outer layer of columnar cells Inner layer of columnar cells Knamel -Vertical section of human enamel and Nasmyth's membrane, sViowing the latter to be composed of what appears to he two layers of columnar epithelial cells. (V. A. Latham.) X 250. ■■1 ^^HHiPl^>^^^S^Ii^^^^^^^^^^l ^^^^^^^^^H^l ■p^pv^^ . . ' '^^IH^^^^^^^H BR^ - #'v » ^'^fli^^^^^^^^^H ^'' «»* .4. nK^^^^^^^^^^^B ^^^^^^^^HHpi^ r; * •, « ^ ^^l^^^^^l ^^^^^^B^ .*^ •* * i ' * ■ ^H^H^B • >r •'",■•4- - • • , '"- ™ • » » • ■ 't * •*' * «v - , ^^r ^ •»'-**'*- *'^*. • r »^ " * _ ^^S^ "* ^ " 4- - ^_^ , ^^ * ^ '• ♦" '^ * '.. ♦ " * • ^> . J * , ** «'^Jh^| " -•» ' ^ >»■ ^tdi^^H Mm. ^MHM H^^^^g^ ' Bj|liM|||to» . i*"^ ^^fll^^^^^H nnn Fig. 183. — Section of normal pnli>-ti^~u( , sluiwiiii; its variniis forms of cells and the hair-like processes. (V. A. Latham.) ■; 143. Fia. 184. — Section of normal puIp-tissue, b.ho\ving odontoblastic layer. (V. A. Latham.) x 145. ) > \ '^ : 1 Fig. 185. — ^Injected blood-vessels of the pulp. (After Stowell.) Fig. 186.— Vertical section of developing teeth of kitten. Injected to show blood-supply of pulp. (V. A. Latham.) )< 10. Pig. 187.- -Vertical section of human deciduous molar in sthi. {\ . A. Latham.) >; Injected to sliow blood-supply of the pulp. HISTOLOGY OF THE DENTAL TISSUES. 55 Huxley, Kolliker, Waldeyer, and Eose liave each maintained that the cuticula dentis was derived from the epithelium of the enamel organ, , "Waldeyer stating that it was the product of the outer tunic of the enamel organ. Paul (1896) has shown that the membrane was composed of flat epi- thelial cells. These could come from no other source than some i^art of the enamel-organ, probably from the outer tunic. Paul suggests that its function is to protect the enamel from the action of acids. C. S. Tomes, who formerly held the view of his father, now agrees substantially with Paul. He says, '' The more recent investigations of Dr. Paul have thrown a fresh light uidou the matter, and have shown that the points upon whicli I chiefly relied are susceptible of quite a different explanation." Sudduth thinks it is derived from a metamorjihosis of the ameloblastic layer, the prismatic cells of which assume a horizontal direction. Mrs. Emily ^unn Whitman has noted these changes in studying the develop- ment of the teeth of the rat and the rabbit, and has ' ' traced the gradual transition of the enamel-rods into a perfectly homogeneous membrane, the cylindrical cells growing shorter and shorter as they approached the sur- face of the crown, until, instead of being columnar, they are almost square, and finally flattened, while at the last the outlines of the cells quite disap- pear, and there is left a perfectly homogeneous membrane." From the appearances in the illustration (Fig. 182) of a vertical section of the enamel and I'J'asmyth's membrane, it would seem that it was un- doubtedly formed from the outer tunic of the enamel-organ, and that the columnar character of the cells was maintained in the formation of the mem- brane. It will be noticed by a reference to the illustration that in this case the membrane is composed of two layers of columnar cells superimposed one above the other. The section illustrated was taken from a depression in the surface of the enamel where it would be protected from wear. This membrane, from its resistance to acids and alkalies, putrefaction, boiling, etc., would seem to be composed of the same substance as the matrix of dentin. THE TOOTH-PULP. Thepulpa dentis, the organ occupying the central cavity or pulp-cham- ber of a mature tooth, is the remnant of the formative organ of the den- tinal tissue, and the source of the nutrition and nerve supply of the fully formed dentin. The tooth-pulxD, which is often erroneously termed the "nerve," is composed of a very delicate connective tissue, nucleated cells, blood-ves- sels, and nerves, while in general outline it corresponds very closely to the exterior form of the tooth. The matrix, or basis substance of the pulp, is composed largely of a kind of undeveloped soft connective tissue, possibly belonging to the mucous or gelatinous species containing numerous cellular elements (Ziegler) of rounded, oval, and spindle forms, with slender, hair- like processes (Fig. 183). The interspaces between the fibres are large and filled with a jelly-like material, which gives it an appearance common to many forms of embry- onic tissue. 56 operativp: dentistry. The cells of the pulp are fairly abundant, but not sufficiently numerous to form a tissue of themselves ; they are found scattered throughout the matrix, embedded in the jelly-like material within the interspaces, and upon the perij)hery. The form and distribution of the cells varies very considerably in different parts of the pulp. In the deeper coronal portions the cells are not numerous ; they may be spheroidal, oval, or spindle-shaped, and have no definite order or relations to each other, while in that portion within the root-canals the cells are arra>nged parallel with each other and with the root. As the periphery of the pulp is approached the arrangement of the cells becomes more orderly, many cells having three or more processes are seen, some extending towards the pulp, while the others are directed towards the dentin and pass between the odontoblasts. The last-named cells — the odontoblasts — are arranged in a definite order, side by side, in a single layer over the whole periphery of the pulp, covering it as with a delicate membrane or epithelium (Fig. 184). The odontoblasts are fur- nished with three sets of processes, as already described, one set con- necting it with its fellows, another with the connective tissue of the pulp proper, and a third which pass into the dentinal tubuli. The blood-vessels of the pulp are numerous; three or more arteries often enter at the apical foramen, divide into innumerable branches, and form an extensive net- work, as shown in Fig. 185, terminating in a rich capillary plexus beneath the layer of odontoblastic cells. Fig. 189. rpj^jg ^g ^^^^1 illustrated in Fig. 186, made from a section of the jaw and developing teeth of a kitten injected for this purpose. The veins are also numerous and somewhat larger than the arteries. The blood-supply, however, is better shown in Fig. 187, which is made from an injected human decidulous molar. They form frequent anastomoses near the surface, as shown in Fig. 188, which is also made from an injected specimen. Lymphatics have never been demon- strated in the pulp. The nerves of the pulp enter the apical foramen either in a simple large trunk or by several smaller ones. They pursue a parallel course, giving off but few branches until Nerves of dental ^]^g pulp -chamber is reached, when they divide into numer- ous branches, going in all directions, and forming a minute net-work just beneath the odontoblasts, where they end in non-meduUated fibres (Fig. 189). Many terminal fibres pass between the odontoblasts to the dentin ; but the final distribution of the fibres has never been satisfac- torily demonstrated. THE PEEIDENTAL MEMBRANE. The peridental membrane, pericementum, or the alveolo- dental perios- teum (Fig. 190), is a fibrous connective-tissue structure which covers or invests the root of the tooth from the cervix to the apical foramen (Fig. 191), just as the periosteum invests the bones (Fig. 192) and lines the walls of the alveoli, having few elastic fibres, and richly supplied with Fig. 188. — Section of injected dental ])uli). ; Pericementum - Alveolar process Pericementum Alveolar j)rocess Fig. 190. — Section of jaw of field-mouse, showing pericementum and alveolar process between the teeth. (V.A.Latham.) X 100. Nerve ' Blood- vessels Odonto- blastic layer Fui. ]yi.— Transverse section throug-h pulp-chamljer of human cuspid tooth. Ulna Periosteum Fig. 192.— Transverse section of forearm of a child, showing jjeriosteum surrounding the bones. X 13 Peridental membrane Fieridental membrane, showing epithelial bodies or glandular .structures. (F. B. Noyes.) X "00. J), dentin ; C, cementum; C'6, cemeiitoblasts ; i?, epithelial bodies : F, F, white fibres. Fic . 200. — Section of peridental memhrane, showing epithelial bodies or glandular structures. (F. B. Noyes.) X 900. D, dentin ; C, cementum ; Ch, cementoblasts ; E, epithelial bodies ; F, white fibres. Mucous membrane Gum Periosteum Alveolar process reric'cmeutum ( ementum Fig. 201.— Transverse section of the jaw throusrh the mucous membrane, gum, and alveolar process. (V. A. Lalham.) X 00. Mucous membrane and epithelium Bone Fig. 202 — Oljhque sectiou of dental follicle and mucous membrane. (V A. Laihaju.) ' 2G. Fig. 20o. — Glands of Serres. X 50. Fig. 204.— Epithelial layer of mucous membrane in its embryonic stage. A. squamous epithelial cells; B, columnar cells — rete Malpighii. OHAPTEE IV. ERUPTION OF THE TEETH. Definition. — The i3rocess by which the teeth advance from the bony crypts, in which they have undergone the calcification of their crowns and a j^ortion of their roots, and are forced through the gums. Synonymes. — Teething ; cutting the teeth ; dentition. Dentition is a physiologic process having no counterpart in the growth of other tissues. Fig. 205 represents a tooth in the process of eruption, the nearest approach to like conditions being the emergence of the hair-sheaths and the nails. In this use of the term dentition it will be understood that it has no reference to the process of development of the germs of the teeth, but refers only to the process of eruption. Fig. 206, made from a section of the jaw of a young rabbit, and Fig. 207, made from a section of the foetal jaw of a field-mouse, show the relation of the i)rimary and secondary teeth to each other at the period of the eruption of the primarj^ teeth. The process of dentition is divided into primary, the eruption of the deciduous or milk-teeth, and secondary, the eruption of the permanent teeth. li^ormal primary or deciduous dentition begins between the fifth and eighth months after birth, and terminates between the twenty-fourth and thirty-second months. The following table represents the average period of the eruption of the various classes of teeth which constitute the tempo- rary denture : The central incisors from 5 to 8 months after birth. The lateral incisors from 7 to 10 months after birth. The first molars from 12 to 16 months after birth. The cuspids from 14 to 20 months after birth. The second molars from 20 to 32 months after birth. The inferior teeth usually appear a few weeks in advance of the supe- rior. j!^o general rule can be formulated from which, however, there will not be marked and frequent deviations. The variations are so marked in the dates of the eruption of the teeth that no two authors give them exactly alike. Tubercular and syphilitic children erupt their teeth very early, while in rhachitic children the process begins very late. It has been stated that Richard Coeur de Lion of England and Louis XIY. of France were born each with several teeth. It is not a very uncommon occurrence for children to be born with teeth. Haller, in his ''Elements of Physiology," mentions nineteen cases of children that were born with one or more teeth fully erupted. The author has several times been called ui^on to remove teeth from the mouths of newly born infants, and there are few physicians or dentists of 59 60 OPERATIVE DENTISTRY. twenty or twenty-five years' practice who have not had a similar expe- rience. Crump reported to the Virginia Society of Dentists a case of full denti- tion in a child at birth (Pepper) ; while, upon the other hand, the teeth are sometimes entirely suppressed. BoxaTli and Baumes have each recorded a case in which the individual reached old age without a single tooth ever having ap]Deared. A few years ago a Eussian family, father and young son, were on exhibition before medical and dental societies and in various museums under the name of "dog-faced men." The father had no teeth up to the age of seventeen, then four teeth appeared in the lower jaw but none in the upper. The son had four lower incisor teeth but no evidence of any others. The jaws of the father, who was a strong and X30werfully built man, were no larger than those of his little son. The Eruptive Process. — The modus operandi or the character of the agencies by which the teeth are stimulated to advance from their bony crypts and emerge through the gums has never been satisfactorily demon- strated or explained. Several views have been advanced to account for the process, but they are all open to serious objections. The first, and perhaps the oldest, theory is that the tooth is impelled from its crypt and through the gum-tissue by mechanical pressure induced hy the growth or lengthening of the root from additions of dentin at its base. Several strong objections can be raised against this view : first, teeth with very short or stunted roots — roots which are much shorter than the distance from the margin of the gum to the base of the crypt — are often erupted ; second, deciduous incisors are not infrequently found erupted at birth, or make their appearance a few weeks afterwards, which have very little or no roots at all, the crown only being developed ; third, a tooth in which the root is completely developed may remain buried in the jaw until past middle life, and then make its appearance ; fourth, normal teeth, particularly the superior cuspids, are so located in their bony crypts that in the process of the eruption of their crowns the distance travelled greatly exceeds in amount the addition made to the length of the root during the same period. C. S. Tomes says,* "The tooth of a crocodile moves upward, tooth- pulp and all, obviously impelled by something different from mere elonga- tion ; and my own researches upon the development and succession of reptilian teeth clearly show that a force quite independent of increase in their length shifts the jposition of and ' erujits' successive teeth." Another theory advanced to account for the process of eruption is me- chanical pressure induced by the lengthening of the dentinal pap illce or formative pidp. The principal objection to this view is the improbability that the elongation of a delicate and more or less embryonic structure like the formative pulp could produce a sufficient amount of pressure upon the tooth- crown at its base to cause resorption of the overlying bony walls of its crypt without injury to its own structure, or causing deflection of the * Dental Anatomy. Crown Bon Forming root Fig. 205. — Vertical section of the jaw, showing forming mot. X 15. Perma- nent tooth - follicle Fig. 206.— Section of jaw of rabtut >-h<)« ma: deciduous tt eth and follicles of peimanent teeth m «i7i( at the period of the eruption of the primary teeth. ^ 22. Fig. 207. — Lower jaw of tetal field-mouse. < 80. Area of resorption Fig. 208.— Vertical section of erupting tooth of field-mouse, showing area of resorption at the cusp of the tooth. X C5 ERUPTION OF THE TEETH. 61 apical end, and thus producing crooked roots, which is by no means a gen- eral condition. Delabarre suggested that the advance of the tooth from its crypt and its passage through the gum was effected in precisely the same manner as the foetus is expelled from the uterus. He regarded the sac, which he claimed was attached above to the gum and below to the neck of the tooth, as the active agent in the eruption of the tooth, induced by the contrac- tion of its walls, and thus the crown of the tooth was lifted from the base of the follicle and ultimately forced through the uncapped crypt and the gum. This is a very ingenious explanation, and is based upon the supj^osition that there are elastic fibres within the walls of the sac. ^N'asmyth found the sac to be composed of two layers, the inner lamina composed of a layer of cells loosely arranged, with interspaces equal to one-half the diameter of the cell. This inner lamina he thought partook more of the characteristic of a serous than of a mucous membrane. This arrangement of the cellular elements of the inner layer is suggestive of contractile power and expelling force. If elastic fibres could be positively demonstrated as forming a part of the structure of the sac, this would be the most rational theory yet ad- vanced, as it would be based upon the known and demonstrable physiologic function of elastic tissue. In support of this supposition it has been stated that inasmuch as in the periosteum elastic fibres are present in that portion of the membrane which lies nearest to the bone, being in the form of a fine fibrous net-work, that they must also be present in the structure of the pericementum, which is very similar to that of the periosteum. Black, however, in his researches upon the histology of the pericemental mem- brane, was unable to positively demonstrate the presence of elastic fibres. He found the membrane to be composed almost entirely of white fibrous tissue, but when the white fibres were dissolved by the usual reagents — solutions of caustic potash — no elastic fibres could be discovered. Another theory presented was that the eruption of the teeth' was caused by the moulding or building of the alveolus around the roots. This theory is easily disposed of by the statement that the alveolus is not formed around the root, nor the root completed, until after the tooth has been erupted. At the time of the eruption of the tooth the osteoclasts have made an opening in the cap of the crypt (Fig. 208) large enough for the crown to easily pass 5 this leaves a considerable space between the bone and the root, which is occupied by the, at this time, thick pericemental membrane. The latest theory is that suggested by Constant (Journal Britisli Dental Association, 1896), — namely, that the blood-xDressure maybe the force which impels the tooth in its movement from the cryj)t and through the gum, on account of the difference in the blood-supply of the parts. The pulp and the tissues beneath it have a very abundant vascular supply, while those above are not so richly endowed, C. S. Tomes, in commenting upon this theory, says, " It seems very possible that the blood- pressure keeping up a state of general tension may operate to push a solid body in any direction in which there is a diminished resistance. 62 OPERATIVE DENTISTRY. to take up, so to si^eak, any unoccupied space ; but it is difficult to see how it could be efficient without some such concomitant action of absorp- tion. For the movement of an erupting tooth is not alwaj^s by any means in the direction of its long axis ; for instance, the developing tooth of the frog, the newt, or of the crocodile takes a sidewise journey, by which it travels underneath the old tooth before it moves upward at all." But if its path be prepared by absorption of the structures in its way, then it is very possible that the blood- pressure keeping up a certain gen- eral tension may suffice to move it along a track of diminishing resistance. Mr, Constant's suggestion, with a little modification, is the most plausible that has been offered, therefore, as to the actual motive force ; whether it will be regarded as a final solution of the question time alone can show." What are the forces which set in operation the process of eruption ? is a ques- tion which very naturally arises in discussing this phase of the phenomenon of the eruption of the teeth. If the lengthening of the root, the elonga- tion of the pulp, or the blood-pressure within the pulp are not sufficient as mechanical forces to produce the adequate i)ressure or mechanical irri- tation necessary to stimulate the osteoclasts to the performance of their function of tearing down the structures which their sister cells, the osteo- blasts, had so lately built up, what other force or forces are operative in establishing this phenomenon % It is possible that it is due to some change in the nutrition of the walls of the crypt and the gums, induced, perhaps, by the withdrawal of a portion of its blood-supply, as a result of the greater activity in the growth of the tooth-follicle just preceding and during the period covered by the process of the extrusion of the crown. In some such change as this in the nutrition of the part the resorption of the alveolus is induced after the extraction of a permanent tooth. The whole subject, it will be seen, is far from being satisfactorily set- tled, either as to the conditions which induce resorption or the forces which are operative in extruding the tooth-crown from its crypt to its normal position in the mouth. When the formation of the tooth has arrived at that stage in which it is ready to be extruded, and this occurs in the deciduous central incisors, which are the first to be erupted, at the fifth to the eighth month after birth, a very active process of resorption, the result of a low inflammatory condition, takes place in the walls of the bony crypt in which the crown of the tooth is lodged. This process is most active at the anterior or labial wall and the roof of the crypt, by which the upper portion of the sac and the bony tissue are removed, as shown in Fig. 209, while the posterior or lingual wall remains unchanged, as it is required to form the labial wall of the crypt of the successional tooth. Prior to this, however, there is formed in the tissues immediately above the bony crypt of the follicle an inflammatory area in which resorption vacuoles are formed which gradu- ally increase in size. The opening made by this process (Fig. 210) finally becomes larger than the diameter of the crown, thus giving it a roomy exit I but as soon as the crown has passed from the crypt and extruded through the gum, the process of resorption gives place to that of a deposition of new osseous material, which loosely embraces the cervix of the tooth. Alveolar bone Fig. 209. — Vertical section of erupting tooth of field-mouse, showing area of resorption, x 75, Fig. 210.— Vertical section of human cuspid, x 75. ERUPTIONT OF THE TEETH. 63 Fig. 211. Rami at various ages. A, childhood; B, adult life ; C, old age. Growth of the Jaw. — As the root of the tootli increases in length additions to the margin of the alveolus keep pace with it ; and as the process is a somewhat rapid one, the increase in the depth of the jaw is correspondingly rapid. This phenomenon begins first in the anterior portion of the jaw by the eruption of the incisor teeth. Later the first molars are extruded, and the jaw deepens posteriorly ; then the cuspids make their appearance, and still later the second molars, producing a corresponding deepening of the jaw in these locations. During this time there has also been a steady lengthening of both the horizontal and the ascending rami of the mandible, with a considerable change in the angle formed by their union. These changes progress until adult life is reached, when they assume an angle of about forty- five degrees. In old age, after the teeth are lost, the alveolar j)i*ocesses are resorbed, and the rami again assume a more obtuse angle, approaching that of childhood. (See Fig, 211.) The changes which occur in the -su- perior maxilla are similar, so far as the deepening and lengthening of the jaw are concerned, to those which take place in the growth of the mandible, while the retrogressive changes are confined to the resorption of the alveolar processes. The eruption of the teeth is not a continuous process, as was pointed out by Trousseau ; the teeth being erupted in pairs or groups, with vary- ing periods of rest between them. The deciduous central incisors are the first of the dental seiies to be erupted ; the ax)pearance of these teeth is followed by a period of rest in the process of from one to two months ; the lateral incisors are next ex- truded, and their appearance is followed by a rest of from five to six months. The first molars come next, and these are followed by the cus- pids, with a period of inactivity in the process between them of from two to four months. The second molars are the last of the deciduous teeth to be erupted, and they make their appearance from six to twelve months after the extrusion of the cuspid. It will therefore be seen that the whole period of time consumed in the eruption of the deciduous teeth is about two years, but the actual time occupied by the various groups of teeth in the passage from their bony crypts and through the gum to their normal positions in the mouth is much less than this; the usual period of time consumed by each group is only from four to eight weeks. The roots of the deciduous teeth are completed in formation at about the following periods and in the order named, but no positive rule can be laid down from which frequent deviations will not be observed : 64 ■ OPERATIVE DENTISTRY. The central incisors are completed at about the age of 2 years. The lateral incisors are completed at about the age of 2i years. The first molars are completed at about the age of .2} years. The cuspids are completed at about the age of 2'i years. The second molars are completed at about the age of 3 years. Fig. 212 shows tlie jaws of a child at three to tliree and a half years of age. MOEBID PRIMARY DENTITION. The eruption of the teeth in a normal child is productive of so little general or local disturbance that many times the teeth make their appear- ance within the mouth before the parent or nurse have realized the fact that the process of '' teething" had really begun ; while, upon the other hand, in children with impaired health and low vitality it often plays a Fig. 212. Jaws of a child of three to three and a half years of age. prominent part in exciting various morbid conditions of the digestive, nervous, respiratory, and dermal systems. The subject becomes, therefore, one of considerable interest, alike to the general practitioner and to the dental specialist. There is no doubt that the dangers from dentition have been greatly exaggerated by some authorities, and that parents are often unnecessarily anxious for their offspring during this period ; yet it must be borne in mind that in certain temperaments and under various physical conditions and environment there is a real degree of danger present, and that morbid phenomena are sometimes excited which may progress to a fatal termination. According to the mortality tables of London, as cited by West, denti- tion was assigned as the cause of death of 4.8 per cent, of all children Deciduous tooth Follicle of permanent tooth Fig. 218.-Vertical section of jaw of embryo cat, showing deciduous tooth and follicle of permanent tooth. X 90. Follicle of per- manent tooth Fig. 2U.— Oblique section of jaiv of embryo cat, showing deciduous tooth and follicle of permanent tooth. X fO. ERUPTION OF THE TEETH. 65 dying under one year of age, and 7.3 per cent, of those who died between the ages of one and three years. The dangers surrounding the period of dentition are much greater in large cities and in overcrowded localities, particularly among the middle and lower classes of society, than in the suburban and county districts. But the greatest mortality is in the foundling hospitals and in overcrowded and filthy tenements. It therefore becomes a question of how much of this mortality is really due to the nervous irritation induced by the eruption of the teeth, or to other concomitant causes. Errors in diagnosis of abnormal conditions oc- curring at this period are by no means uncommon, and it is to be feared that dentition is sometimes made the scapegoat for the ignorance of a medical or dental attendant, or the carelessness or indiscretions of the parents or nurse. Contemporaneously with the eruption of the teeth there is a very im- portant developmental process taking place in the follicular or glandular apparatus of the whole alimentary canal, in preparation for the necessary change soon to take place in the character of the food. This is a x>hysiologic process, and under normal conditions, when all of the functions of the body are nicely balanced, progresses without any disturbance of the general health ; but under opposite conditions it may be productive of serious gastric and intestinal complications, the causes of which are often entirely overlooked, and the disturbances which are the result of this process are attributed to morbid dentition. The nervous system of the child at this period is also very imj)ressible, the cerebro-spinal apparatus j)redominating to such an extent that slight irritations of almost any character, in children of certain temperaments, may be followed by more or less general systemic disturbance, with eleva- tion of temperature, vomiting, diarrhoea, bronchitis, and other catarrhal conditions, or reflex nervous phenomena, like strabismus, twitching of the facial muscles, rolling of the eyes, convulsions, or meningitis. Dental Irritation. — The nervous irritation accompanying the erup- tion of the deciduous teeth may be caused by one or all of the following conditions : 1. By the very active evolutionary process going on within the jaws at this period. 2. By the lateral pressure induced within the jaws by the contempora- neous evolution of two sets of teeth. 3. By peripheral irritation of the gingival nerves from the pressure of the advancing teeth. (1) The very active evolutionary process which is going on within the jaws at the period of the eruption of the teeth calls for a much larger volume of blood within the i^arts than is normal at a later period in life. The illustrations shown in Figs. 213 and 214, made from the jaw of an embryo cat, show what a considerable amount of space is occupied in the jaws at this period of dental evolution by the follicles of the teeth. This, under certain conditions which have already been mentioned, often pro- duces over-stimulation of the parts, followed by congestion, which may induce reflex nervous phenomena, or through the sym]3athetic nervous 5 6Q OPERATIVE DENTISTRY. system establish morbid conditions of the stomach, the bowels, the respira- tory tract, the skin, etc. (2) The lateral pressure induced within the jaws by the contempora- neous evolution of two sets of teeth must be very considerable at this pe- riod. If the jaws of a child six months old are examined it will be noticed that the permanent teeth in various stages of development are so crowded together that their crypts overlap each Fig. 215. other, but each apparently is striving to obtain a normal position. As the growth and enlargement of the jaws takes place they gradually assume their proper posi- tions within the arch, ready to advance as soon as the way is made clear for them by the lengthening of the jaws and the exuviation of the deciduous teeth (Fig. 215). (3) The peripheral irritation of the gingival nerves from the pressure of the advancing teeth is often under-estimated, as any individual will readily admit who tirst and second dentition, upper and lower Jias Suffered from the eruption of a ™*^^ ^' troublesome third molar. In viewing the subject of dental irritation from this stand-point the wonder would seem to be that morbid phenomena are not more often manifested than they are during the eruption of the deciduous teeth. Symptoms. — The symptoms of dental irritation may be classified under two heads, — viz., constitutional and local. The constitutional symptoms which may be manifested as complications during the period of first dentition are fever, diarrhoea, vomiting, cough, bronchitis, various eruptions of the skin, occasionally swelling and suppura- tion of the lymphatic glands, and nervous phenomena like spasms of the facial muscles, "which send doting mothers into ecstasy over the heavenly smile of the sleeping infant," strabismus, chorea, convulsions, and meningitis. Pyrexia, or fever ^ is perhaps the most common constitutional symjptom or complication of morbid primary dentition. The character of the fever may be mild or intense, according to the degree of suscei)tibility of the child to nervous irritation, and there is a marked difference in children in this respect. In one child the elevation of temperature may be slight, not going above 100° F., while in another, with apparently no greater cause for an abnormal rise in temperature, it may reach 103° or 104° F. , and be accompanied with gastric or intestinal disturbances or convulsions. The fever of dentition, which is irritative in character, is peculiar in that it is very irregular in its manifestations. It is often higher in the morning than in the evening, reversing the usual order, and it varies con- siderably from day to day. A high morning temperature often follows a restless night, and a low evening temperiature follows a quiet day. Great Adgilance should characterize the care of children when suffering from the irritative fever of dentition. A feverish child is very susceptible to sudden ERUPTION OF THE TEETH. 67 clianges of the weather from a dry to a damp atmosphere, from a warm to a cold room, or to cold draughts, and to improper feeding. Too much emphasis cannot be placed upon the importance of iDroperly protecting the child against these contingencies. Catarrhal attacks at this period are far more likely to be the result of exposure which has induced a chill, or to improper feeding, than to mechanical irritation of the gingival nerves by an erupting tooth. Diarrhoea is another very common complication of morbid dentition, but dental irritation is by no means the most common cause of diarrhoea. Catarrhal conditions of the stomach and bowels are very jDrevalent at this period 5 but in the opinion of the writer these conditions are more often the result of bad sanitary and hygienic surroundings, exposure to cold, or improper feeding and unwholesome food than to any other cause or causes. Diarrhoea and vomiting are most prevalent during the hot months of the year, when the changes in the weather are often the greatest and the clothing of the child least likely to afford the pro]3er protection against a sudden fall in the temxDerature. The food also is more liable to be ren- dered unwholesome by fermentative changes during the hot weather than at any other time. A chill or a cup of milk partially changed by lactic acid fermentation, or the impure, chemically preserved stuff often sold in our large cities as pure milk, are responsible for a large majority of the cases of gastric and intestinal disturbances and nervous phenomena. Parents and nurses through ignorance or carelessness often feed little children with foods that their stomachs, at this early age, are incapable of digesting 5 for instance, meats, hard-boiled eggs, beans, cabbage, bananas, apples, cherries, and many other similar things ; and then, if the child's stomach refuses afterwards to retain food, or it suffers from diarrhoea or cholera infantum or convulsions, and as a result gives up its puny life, the illness or the death is often charged to teething. Bronchitis is usually attributed to ordinary exposure, and yet it some- times occurs in children in whom every precaution has been taken to pre- vent chilling the surface of the body ; under such circumstances it may be the result of dental irritation. Cutaneous eruptions frequently occur during primary dentition, such as urticaria, eczema, impetigo, lichen, prurigo, and herpes zoster, which are often the exj)ression of reflex nervous irritations. Reflex nervous phenomena^ associated with morbid dentition, are of the most varied character, both as to degree and the peculiarities of their manifestations. These manifestations are often difficult to understand, and still more difficult to trace to their origin. Pepper says, in explana- tion, "Doubtless the extensive ramifications of the great vagus nerve and its connections, both of origin and distribution, with the exquisitely sen- sitive fifth nerve, as well as with the facial nerve, and with the sympa- thetic system, will explain why the irritation should now be seated in the gastro- intestinal tract, giving rise to vomiting and diarrhoea 5 now in the respiratory tract, provoking cough more or less severe, or even a well- marked bronchitis ; now manifests itself in various cutaneous eruptions ; now accumulates in the cerebro-spinal axis, manifesting its presence by 68 OPEKA.TIVE DENTISTRY. slight spasms, or dischargiug with terrific force in some of those convul- sive seizures which are the dread of mothers and the cause of much anxiety to physicians." The second summer is generally considered as the most critical period in the life of the infant, the popular notion being that the dangers and com- plications which arise are largely due to the eruption of the cuspid and molar teeth, as one or the other of these groups usually makes its appear- ance at about this time. There is really no reason why a cuspid or molar tooth should cause a greater degree of irritation than an incisor ; while, upon the other hand, in a normal child, with the increase in the age and strength, there usually comes greater resistive power to such forms of irri- tation ; consequently the second summer should be less dangerous than the first so far as dentition is concerned. The dangers associated with the second summer do not in any great measure depend upon dental irritation, but rather upon improper feeding. Children of this age are prone to devour anything that may be given to them, or upon which they can lay their hands, and unless they are care- fully watched and strict supervision instituted over their food, as to its kind, quality, and quantity, many illnesses are likely to occur ; and if a group of teeth — the cuspids or molars — should be erupting when the illness supervened, the chances are that they would be considered the primary cause of the derangement rather than the ingestion of indiges- tible substances or foods in which fermentative processes had already been established. When these conditions are complicated with the debility con- sequent upon previous disease or a period of intense heat, the results often prove fatal. A very large percentage of all the children born die before they reach the end of the fifth year as a result of the diseases and accidents peculiar to this period of life. Arbuthnot calculates that one in every ten children dies from the effects of the associative and influenced lesions of the age. (Garretson.) The mortality among hand-fed children is much greater than this. Camper is the authority for the statement that out of five thousand nine hundred and eighty-nine children admitted to foundling hospitals, only eight hundred and eighty-four were found living at the end of the fifth year (Garretson), or 85. 239 per cent, had died. Eouth says, in this connection, ' ' In England, out of one hundred chil- dren born and fed by hand, 15.2 per cent, will die the first month, 1.7 the second, and so on. In France, out of one million births, 20,121 die in the first week, 22,128 in the second, and 22,236 in the sixteen days following." According to the English Life Table, ' ' the annual rate of mortality among infants per thousand is equal to 571.3 in the first mouth of life, de- clining, however, to 91.6 per thousand in the eleventh month. The annual rate among infants aged one month and under one year does not exceed 114.6 per thousand, whereas among infants from birth to one year of age it is equal to 165.6 per thousand. ''Among infants of six months the mortality is but one-fifth of the rate which i)re vails during the first month of life." {British Medical Jour- nal, vol. i., 1875, p. 785.) ERUPTION OF THE TEETH. 69 The report of the Eegister-General of England for 1897 shows that "under the most favorable circumstances the mortality of infants under one year of age is very high. Reference to several life tables shows that the same rate of death is not again experienced until the age of about eighty years. But the mortality in the first year of life is by no means evenly spread over that year ; about one-half of it occurs in the first three months. The following table shows the survivors at three months, six months, and twelve months out of one hundred thousand of each sex born in 1881-90 ; the deaths in the intervals are likewise shown." England and Wales. England and Wales. Born and Surviving at Each Age. Dying in Each Interval of Age. Males. Born 100,000 Three months 93,791 Six months 88,895 Males. Between birth and three months 7880 Between three and six months 3225 Between six and twelve months 4999 Twelve months 83,896 Females. Born 100,000 Females. Between birth and three months. . . . 6209 Three months 93,791 Between three and six months .... 2653 Six months 91,138 Twelve months 86,887 Between six and twelve months 4251 The rate of mortality among infants of both sexes under the age of twelve months was equal to 142 i^er thousand births registered as comj^ared with 149 per thousand in the preceding decennium. In 1881-90 the infantile rate among males was equal to 155 per thousand births, and among females to 128 per thousand, the rates in 1871-80 having been 163 and 134 re- spectively. Local Symptoms. — The local symptoms which usually accompany first dentition are as follows : Salivation is the first indication of ap- proaching dentition. From birth to the fourth or fifth month the sali- vary glands seem to remain nearly or quite inactive, but as the time ap- proaches for the teeth to begin the process of eruption the salivary glands take on a marked activity, the fiow of the secretion being so abundant as to cause it to dribble from the corners of the mouth and to wet the garments about the neck and chest. This wetting of the clothing is often respon- sible for the catarrhal attacks associated with dentition, while the swal- lowing of large quantities of saliva has been thought in some cases to be responsible (Pepper) for the diarrhoea by reason of its saline constituents, which may act as a mild cathartic. Swelling or tumefaction of the gums is next observed, at about the sixth to the seventh month, in those locations where the teeth are about to be erupted. Sometimes the gums become congested, tense, glistening, hot, and painful ; at times tender to the touch, but generally the painful sensa- tions are relieved by pressure, hence the desire of the child to bite upon hard substances. 70 OPERATIVE DENTISTRY. Accompanying these local symptoms there is often a slight elevation of temperature with flushing of one or both cheeks, irritability of temper, peevishness, and restlessness during sleep, with rolling of the head from side to side. Occasionally the child sleeps with the eyelids only half closed or the eyes rolled upward. Otalgia is not an uncommon occur- rence, as may be inferred from the child poking its fingers into the ex- ternal meatus or pressing its ear into the pillow or against the bosom of the nurse. In the ordinary cases of dentition these may be the only mani- festations. In the more severe cases one or more of the constitutional symptoms above described may be present as comj)lications. Occasionally there exists a disposition to the formation of aphthous patches, ulcerous stomatitis, within the mouth, upon the lips, cheeks, gums, and tongue, most frequently, however, at the commissure of the lips, upon the buccal surface of the alveolar ridge, and the tip of the tongue ; the latter being due, in all probability, to the friction of the sharp and ser- rated edges of the incisor teeth. Sometimes in children suffering from debility the aphthous patches be- come confluent, forming large ulcerated surfaces ; or the gums over the advancing teeth become ulcerated, exceedingly tender and painful, — odon- titis infantum, — or gangrenous, forming large, foul-smelling sloughs, — gan- grena oris, — which expose the teeth and the bone. Both of these conditions are difficult to cure, the latter often taking on the more severe and fatal form of gangrenous ulceration known as noma. A more common but less severe form of stomatitis, in which there is a general inflammatory condition affecting the mucous membrane, and espe- cially the mucous follicles of the tongue and cheeks, — catarrhal stomatitis, — accompanied by swelling of the submaxillary glands and infiltration of the surrounding connective tissue, is frequently seen in the children of the very poor, and is usually associated with bad or insufficient food and unsanitary surroundings. Constitutional Treatment. — The treatment of morbid dentition with its constitutional and local complications generally falls to the lot of the family physician, and the dental surgeon or stomatologist is rarely con- sulted except in the more severe cases involving serious oral lesions or re- flex phenomena dependent upon oral conditions. It will not be necessary, therefore, to dwell at length upon the treatment of the various general morbid conditions which accompany difficult dentition, as these belong to the realm of general medicine, and those especially interested in this part of the subject can refer to works devoted to this department of medical science. It will be sufficient to say, then, that the constitutional symp- toms are to be treated upon general principles, i\xQ first of which is to ascer- tain the cause, second, to remove it if possible, and third, to assist nature in re-establishing a normal condition. It will not be amiss, however, to quote a few lines irom Day (" Diseases of Children") upon this part of the subject. He says, " The treatment of dentition will depend upon the general symp- toms that are present and the constitution of the patient. The practi- tioner must exercise his own judgment as to the treatment to be adopted, and not blindly attach himself to any routine plan. The strong and vig- ERUPTION OF THE TEETH. 71 orous child who is feverish and thirsty, with a hot and tender gum, a full pulse, and constipated bowels, will demand quite a different mode of man- agement from a puny and rickety child whose teeth are delayed. In strong children a grain of calomel with two or three grains of rhubarb will be required to clear the bowels. A saline mixture, as the citrate of potash, should be given to abate the pyrexia, and if the child is excited and sleepless, a few drops of tincture of henbane may be added, or a draught at bedtime containing hydrate of chloral and bromide of potas- sium should be given. The child's head should be kept cool, and what- ever determines to cerebral congestion should, if possible, be prevented. ''In rickety children a mild aperient is occasionally required, such as bicarbonate of soda and rhubarb, to regulate the bowels and to correct the secretions. A teasi^oonful of castor oil may be advisable now and then, and if the bowels are overactive, a grain of Dover's powder at bedtime is often of great service. If there is vomiting and flatulence, some carmina- tive will be necessary. In cases where there is much restlessness and dis- turbance of the nervous system, bromide and iodide of potassium with sal volatile will often abate sickness and relieve head-symptoms if present." Local Treatment. — In those cases in which the gums are considerably congested and swollen, causing jyain on pressure, and accompanied with gen- eral febrile symptoms, vomiting, diarrhoea, or cough, almost immediate relief is often obtained by the free use of the gum-lancet. To be effective the lancet must reach the tooth. The incision for the six anterior teeth of each jaw should follow the line of the niorsal or the cutting edge of each tooth, except in the cuspids when the cusp has penetrated the gum (Fig. 216), when the incision may be made as shown in Fig. 217, while for the Fig. 216. Fig. 217. Fig. 218. Fig. 219. Fig. 220. molars crucial incisions should be made, one from the disto-lingual cusp to the mesio-buccal, the other from the disto-buccal cusp to the mesio- lingual (Fig. 218.) These incisions follow the line of the cutting edge in the six anterior teeth, and cut directly across the cusps of the molar teeth which are nearest the surface of the gum (Fig. 219), and for that reason are to be preferred to those which are made upon the lines of the sulci between the cusps, as shown in Fig. 220. The indiscriminate use of the gum-lancet, however, should be depre- cated. Much harm has often been done by a thoughtless or empirical use of this valuable means of treatment, while, upon the other hand, many lives have been saved by an intelligent use of it. Many writers and physicians of experience have claimed that its use is never indicated, and when used it is productive of more harm than good. 72 OPERATIVE DENTISTRY. The same has been said of blood-letting in pneumonia, and yet, in certain cases, there is not a more valuable means of treatment known to medicine than this once much-abused and now often- maligned procedure. The dif- ficulty and danger in both of these methods of treatment do not lie in the methods, but in the discriminating power of the person who employs them. If the gum-lancet is applied before the tooth has advanced from its crypt, the incision will necessarily be deep, and the end sought for— viz., the extrusion of the tooth through the gum— will not be realized ; conse- quently the lips of the incision will unite again ; and if this procedure is repeated, and it frequently is, a mass of cicatricial tissue is formed that is likely in a frail and debilitated child to become the seat of ulceration when the tooth shall finally make its appearance through the gum. Such an indiscreet use of the gum-lancet cannot be too strongly condemned, for the irritation certainly does not come from pressure upon the gingival nerves until the tooth advances from its crypt. Dental irritation which does not produce local symptoms within the mouth — swelling or congestion of the gum, or both — is not due to pressure upon the gingival nerves, but rather to one or both of the other causes of dental irritation before mentioned. The ojyeration of lancing the gums is best performed with the assistance of a nurse. In operating upon the lower jaw the child should be seated in the lap of the operator, with its head against his breast, the Fig. 221. j^ands and feet being controlled by the nurse. The left thumb of the operator is placed in the mouth of the child upon the tongue, the index-finger between the alveolar ridge and the lower lip, with the remaining fingers under the chin. In this way the head can be firmly held, the tongue controlled, and the lip held out of the way ; it also gives a good view of the inferior alveolar arch, and permits the operator to reach any i^art of it with the lancet. The best form of gum-lancet is shown in Fig. 221, which is a flat blade turned at right angles to. the shaft, and having a sharp, rounded edge. In oxDerating upon the uj)per jaw the child should be laid upon its back in the lap of the nurse, with its legs passing under her arms, while the arms of the child are held firmly to its sides. The head should be held between the knees of the oi^er- ator. One or more fingers of the left hand of the oiDerator are then inserted within the mouth of the child, and the alveolar ridge grasped with the thumb and index-finger. The gum- lancet should be held in the right hand as a pen or pencil is held, and the hand should be steadied by resting the ring-finger and the little finger upon some convenient portion of the face while the incisions are being made. Sometimes it becomes necessary in the eruption of the molar teeth to remove the band of overlying gum-tissue which remains after the cusps have pierced the gum, as it seems to retard the extrusion of the tooth. This can be best accomplished by a pair of sharp-pointed curved scissors (Fig. 222). Gum-lancet. EEUPTIOX OF THE TEETH. 73 Troublesome liemorrliage occasionally follows lanciug of the gums, but, as a rule, the bleeding is so slight as not to need any especial attention. In troublesome hemorrhage the bleeding gums may be bathed with a strong solution of alum, or touched with an alum pencil, or tannic acid in glycerol may be applied upon a piece of gauze or absorbent cotton. In obstinate cases a compress a]3X)lied to the bleeding part, and the jaws closed upon it and held in that position by a bandage passed under the chin and over the head, will usually control it. The application of Monsel's solution or the nitrate of silver is recom- mended by several authorities, but this is rather dangerous practice, from Fig. 222. the fact that they cause sloughing of the surface of the gum-tissue ; this is often followed by secondary hemorrhage, which is sometimes more trouble- some to control than the primary bleeding. As a constitutional remedy, tincture of ergot in one- to five- drop doses in a little water, repeated every ten minutes until bleeding ceases, or until twenty to thirty drops have been administered, will usually prove effective. EXUVIATION OE SHEDDING OF THE DECIDUOUS TEETH. Definition. — The exuviation of the deciduous teeth is a peculiar physiologic process, whereby the roots of the teeth are gradually dis- solved — organic and inorganic material — and their elements removed by resorption. It may truthfully be said that the process of the evolution of the temporary teeth is hardly completed before preparations are made for a retrograde change which shall result in the tearing down of these struc- tures, which have been so carefully and elaborately built, to make room for those larger and more permanent organs which are intended to serve the body to the end of life. The process of exuviation begins in the central incisors in about a year, or a little more, after the complete formation of their roots, — viz., in' the middle or latter part of the third year, — but it is not completed until about the seventh year, when their crowns fall out from lack of support. The lateral incisors are attacked a few months later than the centrals, and are shed at seven and one-half to eight years of age. The process begins in the first molars at the age of six and one-half to seven years, terminating 76 OPEEATIVE DENTISTRY. tissue, instances of which are common in the practice of orthodontia. In moving a tooth from an abnormal to a normal position the orthodontist depends upon his power to produce resorption of the alveolar process by- applying mechanical pressure in a certain direction. Resorption of bone is often brought about by the pressure of an en- larging aneurism or of the accumulations of fluid or of pus, as, for in- stance, in the maxillary sinus, where it sometimes results in the rupture of one of the walls of the sinus. The active agent, apparently, which produces the resorption of the roots of the deciduous teeth is a soft, highly vascular papilla, — the " ab- sorbent organ," — which is found in close contact with the root of the tooth. The surface of the papilla is composed of very large multiform cells, — giant cells, — each cell being composed of several smaller ones, the number varying from two or three to twelve or fifteen. The prevailing forms of the cells are ovoid and spherical, although some of them have the appear- ance of the myeloid cells of Kolliker (Fig. 224). The excavated surface of the tooth lying next to the absorbent organ, if examined microscopically, is seen to be covered with numerous very small cup-shaped indentations, — the lacunae of Howship, — in which a giant cell has evidently been lodged. The modus oj>erandi by which these giant cells affect a dissolution of the dental tissues is not definitely known. Giant cells, however, are always present wherever the resorption of hard tissues like bone is going on, or foreign substances located in the body that are capable of being dissolved. The giant cells which compose the "absorbent organ" are no doubt modi- fied osteoclasts derived from the pericemental membrane of the decidu- ous teeth, and perform the same office for the teeth that the osteoclasts do for the bone, and are known as "odontoclasts." Several theories have been advanced in explanation of the process of resorption of the deciduous teeth. It was thought, until quite a recent period, to be due to the formation or secretion of an acid by the "absorbent organ," which attacked the dental tissues and dissolved them, and that these elements were then removed by the absorbents and carried into the general circulation. Abbott advanced the theory that the absorbent organ was not the active agent in the resorption of the temporary teeth, but rather the result of it. The process of resorption, he believed, was brought about through the living matter, the organic basis substance of the dental tissues, by a retro- grade metamorphosis, or a change to embryonal tissue, and that the process is closely allied to that of inflammation. That the lime-salts are first dissolved and the basis substance or organic material is afterwards liquefied. Medullary elements then arise out of the liquefied material and proliferate, resulting in a new formation of medullary tissue, the so-called " absorbent organ." Black has suggested the most rational explanation of the process, one which is in entire harmony with the latest developments in physiology, — namely, that the absorbent organ secretes or elaborates a digestive fluid or soluble ferment which dissolves or digests the dental tissues and alveolar walls, and prepares them to be resorbed, just as under certain circumstances Pig. 223.— Vertical section of a jirculiar ca^o if uxuviatiiai . 1" a tooth in the jaw of a kitten. X 35. Fig. 224.— Absorbent organ and portion of dentin in situ. A, giant celis. (V. A. Latham.) X G5. ERUPTION OF THE TEETH. 77 bone is resorbed, or ivory pegs wbicli have been driven into tlie tissues, or catgut sutures, silk ligatures, decalcified chicken-bone, drainage-tubes, or even sponges are dissolved and removed by the process of resorption. Devitalized temporary teeth are not resorbed ; hence it would seem that the vital pulp must play an important part in the resorptive process. Pierce says the very moment vitality of the pulp ceases that instant this retrograde metamorphosis, designated "physiologic absorption," termi- nates. Yital permanent teeth sometimes undergo a process of resorption at various points upon the surface of their roots as a result of pericemental irritation or inflammation, and after the subsidence of the morbid condi- tion new bone or cement formation takes place at those points by the cal- cification of the absorbent cells. Tomes says, ' ' The process of absorption once commenced does not necessarily proceed without intermission, but may give place for a time to actual deposition of osseous tissue on the very eroded surface ; probably by the agency of the absorbent cells themselves, which are capable of being calcified in the excavations they have individually made." Eeplanted, transplanted, and implanted teeth are often attacked by a process of resorption which in many respects is quite similar to the re- sorptive process which removes the roots of the deciduous teeth. This difference, however, is to be noted, that while in the deciduous teeth and vital permanent teeth the process leaves a comparatively smooth exca- vation, in devitalized teeth the cementum and dentin become more or less roughened and honeycombed. The latter process is also attended with considerable soreness, due to the pericemental inflammation, and pus not infrequently forms, which may escape around the cervix of the tooth or point through the gum, while in the process as seen in the exuviation of the deciduous teeth no inflammatory symptoms are present. The former is a patTiologic process established to remove an organ which has become a source of irritation and acts as a foreign body. The latter is n physiologic process established to remove an organ which has served the purpose of its creation, but which is to gradually give place to a stronger and more enduring counterpart of itself. Pathology, we are taught to believe, is perverted physiology ; but just where normal func- tion ceases and morbid conditions begin science has not as yet been able to demonstrate. The accompanying diagram (Fig. 225, page 78), drawn by Professor C. E". Peirce, most admirably illustrates the periods at which calcification takes place in the deciduous and the permanent teeth, and also the decalcification or resorption of the roots of the deciduous teeth. ERUPTION OF THE PERMANENT TEETH. Normal secondary or permanent dentition begins at about the sixth year by the eruption of the first molars, which take position directly behind the second deciduous molars, the growth of the jaws having made this possible by increasing the distance between the second deciduous molar and the ascending ramus in the lower jaw, and between the same tooth and the tuberosity in the upper jaw. 78 OPERATIVE DENTISTRY. ,0^ aa MM a a d a u a a a •r' >> >> >> t^'^ 'ii « N i-l *3 ERUPTION OF THE TEETH. 79 The growttL of the jaws, which keeps pace with the eruption of the per- manent teeth, is mainly confined to an elongation of the horizontal ramus between the second deciduous molar and the angle. There is, however, a certain amount of growth taking place at the symphysis menti and at the median and intermaxillary sutures, and also in the interstitial substance of the jaws. This statement is corroborated by the fact that as the period of second dentition approaches, spaces appear between the deciduous teeth which gradually widen until the primary teeth are exuviated. The widest space in the lower jaw is between the central incisors, while in the upper jaw it is between the central incisors and between the lateral incisors and cus- pids. ISTature thus beautifully provides for the increase in the number and of the size of the succeeding teeth by arranging the growth of the jaws in harmony with the space required for a normal arrangement of the individual permanent dental organs. There is often a considerable variation in the time and order of the eruption of the permanent teeth, even in healthy individuals, but the fol- lowing table gives approximately the date and the order in which they may be expected to appear in the dental arch : First molars 5 to 7 years of age. Central incisors 6} to 8 years of age. Lateral incisors 7 to 9 years of age. First bicuspids 9 to 11 years of age. Second bicuspids 10 to 12 years of age. Cuspids 11 to 14 years of age. Second molars lls^ to 13 years of age. Third molars 16 to 21 years of age, or at any period later. The third molars not infrequently fail to appear at all. They are usu- ally developed, but remain in the jaws for lack of space in the arch to accommodate them, or are so malposed that their eruption is dif&cult or impossible. Symptoms. — The symptoms which accompany second dentition are usually so mild as not to attract special attention. There is slight saliva- tion and a little tenderness of the gums over the erupting teeth. Occasion- ally, however, marked symptoms may be present, profuse salivation, great tenderness and tumefaction of the gums, sometimes accompanied with ul- cerative stomatitis, neuralgia of the trifacial nerves, and epileptic seizures. The eruption of the third molars, particularly the inferior ones, is often productive of great suffering from inflammation of the gums and surround- ing tissues. Suppuration not infrequently supervenes, which may extend to the jaw, causing large abscesses and infection of the lymiohatic glands. Abscesses of this character in the lower jaw often burrow downward into the tissues of the neck, involving the imjjortant vessels of this region, the accumulation of x^us being sometimes very considerable. The writer once opened such an abscess from which more than a pint of pus was extracted, and has frequently in his hospital practice treated cases in which half that quantity has been withdrawn from the abscess. 80 OPERATIVE DENTISTRY. Septicsemia and necrosis of the jaw sometimes complicate the affection. The presence of septicaemia adds greatly to the dangers surrounding the case, and may cause a fatal termination. ISTecrosis of the jaw may be of slight or considerable extent. It may involve only a portion of the alveolar process or extend to the body of the bone, destroying large portions of it, or even the entire half of the jaw. The process of eruption of the permanent teeth is so nearly analogous to that of the temporary dentition that no special description seems necessary. Irregularities in the Position of the Permanent Teeth. — In the eruption of the succedaneous teeth — those which succeed the deciduous set — rapid resorption of bone takes place upon the labial and buccal aspects of their crypts, resulting in an opening very much larger than the crown of the tooth. The fact will therefore be recognized that any slight mechanical obstruction situated in the path of its progression would be sufficient to deflect it from its normal course and result in an irregularity in position. The muscular action of the lips and tongue, the habits of tongue-sucking and thumb- sucking, are all potent factors in modifying the arrangement of the teeth when applied at this period of their evolution. Certain develop- mental conditions of the bones of the face are very common causes of irreg- ular arrangement of the permanent teeth, and by some authorities thought to be the most prolific causes, — namely, excessive development and ar- rested or retarded development of the maxillary bones. These conditions may be the result of many and varied causes, some hereditary, others ac- quired. These may again be divided into constitutional and local. Among the constitutional conditions which may be classed as direct inherited causes are, first, constitutional taints, like syphilis, tuberculosis, and neurotic conditions, peculiarities in the formation of the jaws and of the teeth, peculiarities in the arrangement of the teeth in the arch, and tendencies to the suppression of certain teeth, or to the presence of super- numerary teeth ; second, conditions which may be classed as indirect in- herited causes, as, for instance, when one peculiarity is inherited from the father and another from the mother, which combined form an irregularity, like the inheritance of large teeth from one parent and a small jaw from the other. The deformity is not directly inherited from either parent, but indirectly from both. Miscegenation of nations and distinct races is often a prolific source of malformations of the jaws and of irregularities of the teeth, which oper- ates by mixing national and race peculiarities which are more or less antagonistic to each other. Third, acquired constitutional defects. These result from diseases or traumatisms which interfere with nutrition, and thus prevent a normal development of the maxillary bones and the teeth, or cause an abnormal arrangement of the teeth in the alveolar arches. The local conditions which may act as factors in producing an abnormal arrangement of the teeth are : 1. Undue retention of the deciduous teeth or parts of a tooth. 2. The presence of supernumerary teeth. 3. The too early extraction of the deciduous teeth. 4. Injudicious extraction of permanent teeth. ERUPTION OF THE TEETH. 81 5. Delayed eruption of a permanent tooth. 6. Moutli-breathing dne to enlarged tonsils and adenoid growths in the nasopharynx. 7. The habits of tongue-sucking and thumb-sucking. The retention of a deciduous tooth beyond the normal period of its exuviation is often productive of a maliDOsition of the succeeding teeth. ISTature pro- vides for the resorj)tion of the roots of deciduous teeth. Death of the pulp prevents physiologic resorption, therefore the unabsorbed root of the retarded tooth may cause the permanent tooth to be deflected from the normal position. The presence of a supernumerary tooth may also operate in a like manner to deflect the permanent tooth from a proper position in the arch, or so crowd the arch by its presence as to destroy the occlusion. The too early extraction of the deciduous teeth tends to retard the inter- stitial growth of the jaw ; permits the teeth upon either side of the space made by the extraction of the deciduous tooth to move or tilt towards each other, thus robbing the permanent tooth of its required space, and forcing it into an abnormal position, while the extraction of the second deciduous molar before the first permanent molar is erupted permits this tooth when erupted to move forward and occupy the sj)ace needed by the second bicuspid. This procedure also induces, as graphically shown by Talbot, a shortening of the arch of the jaw upon that side, thus crowding the cuspid and bicuspids out of line, and causing a deformity difficult to remedy except by the extraction of one of the bicuspids. The injudicious extraction of permanent teeth often entails a serious incon- venience to the individual by permitting a tilting of the crowns of the proximate teeth and forming large inverted V-shaped spaces which are difficult to cleanse, and therefore invite caries. This condition frequently follows the extraction of the first permanent molar if delayed until after the eruption of the second molar. The extraction of the permanent superior lateral incisors, to make room for prominent cuspids, also causes a deformity in the arrangement of the teeth which cannot, except in rare instances, be corrected, and should be condemned in the severest terms. The extraction of the cuspids is also to be condemned if performed for any other reason than a diseased condition involving contiguous parts. The loss of the superior cuspids is productive of a narrowing of the ante- rior portion of the arch, and depression at the corners of the mouth and alse of the nose. Delayed eruption of a permanent tooth, particularly the superior lateral incisors and the first or second bicuspids, are often productive of trouble- some irregularities. Delayed eruptions of the lateral incisor permits the cuspid to take an abnormal forward position, often approximating the distal surface of the central incisor, and making it imj)ossible for the lateral to occujDy a normal position ; while the non-eruption of a bicuspid permits the approximation of the contiguous teeth, and often destroys the occlusion upon that side. Mouth-breathing, due to enlarged tonsils and adenoid growths in the naso- 6 82 OPERATIVE DENTISTRY, pharynx, is also productive of a narrowing of the superior alveolar arch in the region of the bicuspids and protrusion of the anterior teeth. The writer is aware that in making this statement he places himself in opposition to some of the very best authorities upon the etiology of dental irregularities, but nevertheless he believes that the position of the upper lip and of the cheeks, when the mouth is open sufdciently to permit these subjects to breathe with comfort, is such that steady and continuous pressure is brought to bear ui)on the teeth and alveolar process in the bicuspid region. This force acting upon the crowns of the erupting permanent teeth, which as yet have their roots but partially formed, and have no bony support except the crypt in which they have been developed, and in this resorp- tion of the walls has been so considerable that the opening in it is much larger than the size of the crown, while, furthermore, the alveolar process is not formed around these teeth until after the crown is erupted, cannot but exert a moulding influence upon the iDOsition of these teeth and their alveolar process, narrowing the arch at this portion and protruding the teeth in the incisive region. It seems to the writer that if these facts in relation to the evolution of the teeth and alveolar process are given their full weight in the argument, it must be acknowledged that mouth-breathing is as potent a factor in the production of this class of irregularities as that they are produced by an arrested or retarded development of the jaws, caused by the obstruction of nasal breathing. The habits of tongue- sucking and thmnh-sucldng may also be regarded as factors in the production of protrusion of the anterior teeth. Sucking of the tongue may, by the pressure upon the lingual surfaces of the superior and inferior incisors, cause a protrusion of the teeth of both jaws. While sucking of the thumb may cause a protrusion of the superior incisors by the pressure upon their lingual surfaces, and, when the thumb also presses upon the labial surfaces and morsal edges of the Inferior incisors, it may cause an intrusion of these teeth. These habits do not, as a rule, cause irregularities of the deciduous teeth. This fact has been used as an argu- ment against the possibility of their causing a malposition of the perma- nent teeth. At first the argument seems good, but upon a careful study of the facts and conditions it will be discovered that these habits are rarely confirmed in the child until about the time that it is weaned from the breast or the bottle, which generally occurs when the child is from one and one-half to two years of age. The roots of the deciduous incisors are at this time nearly or fully formed, and the development of the alveolar processes is completed, thus rendering the teeth fairly stable and not easily moved from their posi- tion by such a form of intermittent pressure, while, upon the other hand, when the habits are continued to the period of the eruption of the per- manent incisors, it can be readily understood how, during the passage of the crowns of these teeth through the gums, and during the development of their roots and of the alveolar processes, a very slight amount of pressure, even though of an intermittent character, would be sufficient to divert them from their normal position to an abnormal protrusion of greater or less obliquity. CHAPTEE Y. BACTERIOLOGY OF THE MOUTH. The discoveries wliicli the science of bacteriology has made and ia still making in reference to the causation of disease render it imperative that a knowledge of the bacteriology of the mouth should be possessed by the student and the practitioner who would ai3i)roach a scientific study of dental and oral diseases^ or who would be successful in their treatment. Bacteriology is one of the most exact of the medical sciences, and is governed by the most rigid laws, the slightest deviation from which often vitiating the results of long and laboriously conducted experiments. The student, therefore, who would hope to do original work in this line will need to cultivate exactness in methods and the most scrupulous obedience to those laws which have been found to govern the various phenomena of their natural and artificial growth, and the methods by which their various functions may be proved. 1^0 treatise on operative dentistry written at the present day can be considered as at all complete which does not deal, to some extent at least, with the subject of oral bacteriology ; yet in a treatise of this size it will not be possible to give more than a simple outline of the subject in gen- eral, and this of necessity must be more or less elementary in character. Definition. — The term bacteriology is derived from the Greek paKrr/piov, a little stick, and ?.6yog, science. Bacteriology is that department of biology which deals with the origin, development, and functions of living micro-organisms. With the development of the science of bacteriology, or rather out of it, has grown the germ theory of disease. This theory, when first promulgated, had for its foundation the demonstrable facts that a certain few diseases were caused by specific germs, micro-organisms, or parasites. These statements of fact stimulated further research into the causation of other diseases, many of which, both medical and surgical, were found to be dependent upon specific micro-organisms which had gained access to the tissues of the body. These discoveries have revolutionized the practice of medicine and surgery in all their departments, but the greatest revolution has been in the practice of surgery. "Without the discovery of the pyogenic bacteria and of the other path- ogenic forms now known to science, and without a knowledge of the i)rin- ciples of modern antiseptics which grew out of these discoveries^ much of the success which has been achieved in modern surgery during the last two decades would still be an impossibility. The achievements in modern dental surgery in the prevention and treatment of oral diseases have been due to the discoveries made in oral 84 OPERATIVE DENTISTRY. bacteriology and to the application of the same general principles of anti- septics. PARASITES. Definition. — Parasites are plants or animals which live npon other plants or animals. In the early history of bacteriology scientists found great diflaculty in classifying some of the parasitic forms, from the fact that it was almost . impossible to determine whether they belonged to the animal or vegetable kingdom. Nearly all of the parasites which enter the animal organism are microscopic in size^ hence they have been designated as micro-organisms, microbes, or bacteria. Scientists are now generally agreed in classifying the bacterial forms as belonging to the vegetable kingdom. Bacteria belong to the fission plants, known as ScMzoi^hyta or ScMzopliytes, a division of the Thallojyhi/fa, including those varieties which multiply hj fission or division. These are divided into two sub-classes, those which possess chlorophyll — namely, the Cyanophycew (usually referred to as Algce) — and those having no chlorophyll, or the ScJiizomycetes (usually referred to as Fungi). ''Many of the bacterial forms are so small as to approach the limits of visibility, even when the highest powers of the microscope are employed." When located in the animal tissues, they are often demonstrated with the greatest difficulty, special staining reagents being necessary — sometimes double and triple staining being required — to differentiate them from the cellular elements of the tissues ; even then the demonstration may be unsatisfactory, and it becomes necessary to institute a series of experi- mental cultivations of the products of tissue disintegration in the case, and the inoculation of lower animals with the products of the artificial cultivations before a positive diagnosis can be reached. Miller, in his "Micro-organisms of the Human Mouth" (1882), ar- ranged those fungi which have a bearing upon the hygienic conditions of the body into four groups : 1 . Fission fungi (bacteria) Schizomyceies. 2. Mould or thread fungi Hyphomyceles. 3. Bud fungi (j^east fungi ) Blastomycetes. 4. Animal fungi (Pilzthiere) Mycetozoa. The first of the four groups, the Fission fimgi, are the most important from the stand-point of health and disease, as they are the chief agents in the production of fermentations and putrefactions, and although through these i)rocesses they conserve the life and health of the vegetable and of the animal kingdom, by preventing the accumulation ui3on the earth's surface of dead vegetable and animal matter, reducing them to their origi- nal elements and returning them again to the air, the water, and the earth, they unfortunately have the power of attacking living organisms and exerting most baneful influences upon health and life, and are now recognized as being the active or exciting cause of a very large number of the diseases which attack the human body. The mould fungi (Fig. 226), although widely distributed in nature, have much less importance from the hygienic stand-point. They produce de- Fig. 22H.— Fruit iiiDulil. (Shearer.) X 1^0. ^i f-'^- -« Fin. 229.— Torula, or veast fungi. BACTERIOLOGY OF THE MOUTH. 85 compositions of organic substances, but with less intensity, and with the exception of certain cutaneous diseases, thrush and ringworm, do not cause such profound disturbances in the human body as do the fission fungi, although abscesses and seropurulent peritonitis have been known to occur from inoculation. The hud fungi are even less important as disease-producers than the mould fungi. About the only diseases known to be produced by them are blastomycetic dermatitis and certain catarrhal changes. Fig. 227. ®Tee« . Forms of bacteria. (In part after Fliigge and Zopf.) a, cocci ; b, diplococci ; c, cluster-cocci (staphy- lococci) ; d, coccus chains (streptococci, torula) ; e, surface-shaped colonies (merismopedia) ; /, packet- shaped colonies (sarcina) ; g, a double coccus chain produced by a single fissation of each member in a direction at right angles to the long axis of the chain ; h, vibriones ; i, k, spirilla ; I, spirochsetes ; m, spiromonades ; n, spirulina; o, cladothrix ; p, rods (bacilli) ; q, Clostridium ; r, leptothrix (threads) ; r', articulated threads ; s, rhabdomouas ; t, u, v, zooglcea. The animal fungi, or mycetozoa, are a group of fungus-like saprophytic organisms, the slime fungi or slhne moulds. Most naturalists and bacteriol- ogists class them as fungi or as plant-growths of low type. E. E. Lankes- ter and his followers, however, group them with the protozoa, or lowest animal forms, while others have classed them as protists, or living organ- isms not decisively classifiable as either plants or animals. Of the animal fimgi, mycetozoa, or slime moulds, very little is known. These organisms resemble huge masses of protoplasm, which are found 86 OPERATIVE DENTISTRY. upon decaying vegetable matter. They are the supposed origin of certain plant diseases, such as the " finger and toe" of cabbage roots. Bacteria are divided into three general classes according to their form, —viz., spherical cells, rod forms, and screw forms. Those which are rod- shaped are termed bacilli; those which are spherical are designated as cocci or sphero-hacteria ; while those with screw forms are called sjnrilla. Fig. 227 represents some of the common forms of bacteria. zopf's classification (modified). Group I. Coccace?e. Spherical forms only. Genus I. Micrococcus (Staphylococcus) Division in one direction only, but irregular, so that the cocci after division form irregular clus- ters. Genus II. (Streptococcus) Division in one plane, but regular, so that the cocci form chains. Genus III. Division in three directions at right angles to each other, and in two j^lanes, so cubes are formed. Group II. Rods, straight or curved. At some period of life history, though cocci and other forms may occur. Genus I. Bacterium. Straight rods ; endospore formation does not occur. Genus II. Bacillus. Straight rods ; endospore formation occurs. Genus III. Spirillum. Spiral rods ; spore formation does not occur. Genus IV. Yibrio. Spiral rods ; spore formation occurs. Group III. Leptotrichee. These are all thread forms. This is a practical and convenient classification. Pasteur classified all bacteria under two general divisions, from their relations to oxygen ; one division he termed Aerobes, the other Anaerobes. The aerobic bacteria require Fi-G. 228. the oxygen of the atmosphere in order to maintain existence, and therefore live ui)on the sur- faces of substances. The yeast fungi are examples of aerobic bacteria (Fig. 228). Fig. 229 shows one of the forms of yeast fungi — the torula. The anaerobic bacteria do not require oxygen to maintain existence, hence they live be- neath the surfaces of liquids and within the tissues of living bodies. The Bacterium tetani is an example of the anaerobic bacteria ; oxygen retards its growth or completely arrests its development. A very large proportion of all the bacteria are aerobic. Some of them are so dependent upon oxygen that even the slightest diminution in the Various forms of yeast fungi, a, colonies of round cells (saccharomyces conglomeratus?) ; b, single cells of different forms partly forming daughter-cells ; c, cylin- drical cells of the pellicle fungus (saccharomyces myco- derma). BACTERIOLOGY OF THE MOLTH. 87 amount is sufficient to retard or completely arrest their development. These are termed obligate aerobic bacteria. Others will develop equally well in a medium rich in oxygen, or where there is no oxygen, or rather, independent of the atmosphere. These are called facultative aerobic bac- teria. Nearly all the disease-producing forms of bacteria belong to the facultative variety. The fluids and tissues of the body contain a certain amount of oxygen, but this is soon consumed by the rapid growth and multix^lication of the bacteria ; consequently their development would be arrested or their existence terminated did they not possess the faculty of living under certain conditions without the presence of oxygen. ^' The capability of certain bacteria to proliferate and to manifest their specific action without access of air may explain the progress of tooth caries under air-tight fillings in cases where the softened dentin was not thoroughly removed before inserting the filling." (Miller.) Long exposure of certain forms of pathogenic bacteria to oxygen diminishes their virulence. Pasteur discovered that if artificial cultures were made of the bacterium of chick en -cholera and the cultures exposed to oxygen for a period ranging from three to eight months, the virus be- came very much attenuated. Cultures of the anthrax bacillus when treated in a like manner gave the same i-esults. He found that if a chicken was inoculated with this weakened or atten- uated culture of the chicken-cholera bacillus, it was rendered immune to the action of the virulent virus, and that the attenuated culture of the anthrax bacillus prepared in the same manner rendered sheep immune to inoculations with anthrax, or if the disease was contracted after inocula- tion with the attenuated virus, it appeared in only a very mild form, Paul Bert has discovered that if the anthrax bacillus is exposed to oxygen under a pressure of twenty to forty centimetres, its vitality is com- pletely destroyed. Functions of Bacteria. — Bacteria are often classified according to their particular function ; for instance, certain species are disease-pro- ducing ; these are tevvn^ii pathogenic. Other varieties produce color, — yel- low, white, green, etc. ; these are designated as chromogenic. Another species causes fermentation, and are called zymogenic. Another produces gas ; these are termed aerogenic. Others are endowed with intense putre- factive properties and are known as saprogenic, while many others have not yet had their special functions discovered. A very large proportion of the bacterial forms are saprogenic. When classifying bacteria according to their relations to disease, it is customary to arrange them under two general divisions : 1. Non-pathogenic, or those which do not as a direct cause produce disease. 2. Pathogenic, or those which are the direct cause of disease. Fermentation and putrefaction are the results of the growth and multi- plication of certain forms of bacteria within the substances which ferment or putrefy. Among the non-pathogenic micro-organisms are included the sapro- phytic germs. These are sometimes spoken of as "nature's scavengers," 88 OPERATIVE DENTISTRY. from the fact tliat they prey upon dead and decomposing vegetable and animal matter. These organisms may become indirect causes of disease when they gain access to wounds in which there are pent-up discharges and dying tissues. Under such circumstances they propagate with great rapidity, and produce certain poisonous and irritating substances called ptomaines, which when absorbed by the system give rise to symptoms which are denominated as sejMc intoxication, ptomaine fever, or septiccemia. Such conditions may follow the death of a tooth-pulp, the extraction of a tooth, the wounding of the tissues of the mouth, or a compound frac- ture of the jaw. Pathogenic micro-organisms grow and flourish in the dead and dying matter, and invade the living tissues and destroy them. They also enter the circulation by direct inoculation through wounds and abrasions, and are carried to all parts of the body, and wherever deposited increase in numbers with amazing rapidity, forming fresh foci for the production of poisonous and irritating substances. The chief difference, therefore, be- tween the saprophytes and the pathogenic germs is, that the former act as indirect causes of disease by the production of poisonous substances, which are absorbed by the system ; but they have no power to penetrate the tis- sues or to enter the circulation, while the latter possess this power and act as direct disease-producing agents. The pathogenic bacteria may be divided again into two general classes : First. Micrococci. Second. Bacilli. Each of these classes has been divided and subdivided by the bacteri- ologist into an almost endless variety. This division and subdivision has been made necessary by the discoveries which have grown out of the more thorough and careful study instituted as to their size, form, and length ; their growth, grouping, and manner of propagation ; their action upon the various culture-media ; their chemical reaction ; the color imparted to the culture-media ; their susceptibility to the various staining reagents, and their action uijon fermentable substances and living organisms. Investigation is constantly going on, and almost daily discoveries are being made of new forms of bacteria, or "further research into the life and habits of old forms develops new features and modes of action, which a little while before had not been dreamed of, while the etiology of cer- tain diseases which were before considered as obscure are one by one being cleared up by the discovery of a specific micro-organism, which, when introduced into the system in sufiBcient quantities, will produce the disease." The evidence which has been deduced in regard to the specific nature of the micro-organisms found in anthrax, typhoid (Fig. 230), tuberculosis, tetanus, diphtheria, glanders, leprosy, cholera, bubonic plague (Fig. 231), pneumonia (Fig. 232), erysipelas, actinomycosis, gonorrhoea, and suppu- rative inflammation is beyond dispute, while in many other diseases the evidence strongly points to the presence of a specific germ as the active cause of their development. The Micrococcus is an individual bacterium, the smallest of all the bac- ~: . r' » ^ Fig. 230.— Barterium typhosus. X 1000. % * Fig. 281.— Bacillus testis, and blood-cells of rat. :■ 1000. Fig. 23'2. — Pneumococciis, showing capsule form. (V. A. Latham.) X 1200. KiG. 2o3. — Diploeoccus pneumoniaB. (Fraiikel.) < 1000. Fig. 23-1. — Streptococcus pyogenes. (V. A. Latham.) X 1000. fV K i* ^% # '' * ^<»' <^^'\i •-^ Fig. 235. — Streptococcus in pysemia after erysipelas. (V. A. Latham.) X fi60. . „^-'', • / *I it*t c •F FiG. 236. — Forms of bacteria in pus iidin an ahscess. ■' 700. .1, jius-cclls ; B, micrococci ami diplococci; C, streptococci ; D, tctracocci. "^ V s/V Vi' y 1 ^< Fig. 'J:',;. — Bacillus tuberculosis. X 1000. BACTERIOLOGY OF THE MOUTH. 89 terial forms, spherical, or nearly so, tiny, globe-like masses of matter, in some instances isolated, in others united in pairs, in fours, or in larger numbers, or arranged in chains or chaplets, or deposited in masses of zooglea or gelatinous matrix secreted by the bacteria themselves. When the micrococci are united in pairs they are termed Diplococci (Fig. 227, B)^ when in fours, Tetracocci (Fig. 227, D). When grouped in clusters they are called Staphylococci. When arranged in chains or chaplets they are known as Streptococci (Fig. 227, C). The pneumococcus or diplococcus of pneumonia (Fig. 233) is a good rep- resentation of the diplococci. Among the numerous difficulties which have to be met by the bacteri- ologist and the pathologist is the seeming identity of certain forms of bac- teria found in diseases presenting dissimilar characteristics ; for instance, the Streptococcus pyogenes (Fig. 234) seems to be identical with the Strepto- coccus erysipelatus (Fig. 235), the only discoverable difference being one of size, the coccus of erysipelas being the larger. The cocci multiply or propagate only by fission. The cell elongates prior to its segmentation, when a constriction appears in the centre, which becomes deeper and deeper until complete division of the cell into two equal parts takes place. These new cells soon attain the size of the parent cell, when they divide in the same manner, and so on ad infijiitum. The diplococci, staphylococci, and streptococci are generally found associated with broken-down tissue and discharges which result from in- flammatory action, particularly in the pus-formations of acute abscesses and suppurating wounds (Fig. 236). These are termed the pyogenic cocci, or pus-microhes. The bacillus is an individual bacterium of rod-like form. The bacilli include all of the elongated forms of bacteria, except the screw forms, and such as have a gyratory motion ; these are classed with the genus Spiril- lum. The bacillus tuberculosis (Fig. 237) is a good example of the short rod-like bacilli. A spirillum is an individual bacterium whose elements are curved, often forming a spiral of several turns. Koch's comma bacillus, which is found in the alvine discharges of patients suffering from Asiatic cholera, is a spirillum, and represents a simj^le curved variety, while Miller'' s spiril- lum, which is found in carious teeth, represents the screw or spiral form. Some of the spirilla have flagella attached to their extremities (Fig. 238.) The bacillus of hog cholera is an excellent illustration of a flagellated bacillus (Fig. 239). Some bacilli are rigid, others flexible ; some are motile, others non- motile, and they propagate either by direct fission or by endogenous spore-formation, — the formation of a cell within the body of the parent cell. Multiplication of Bacteria. — -The process of reproduction in bacteria is a very rapid one. Fliigge observed the process of segmentation in a coccus to be completed in twenty minutes. Cohn has made the calcula- tion that if it should take one hour to complete the process of segmentation and for the new cell to attain the size of the parent-cell, one coccus, mul- 90 OPERATIVE DENTISTRY. tiplying by this process, would in a single day produce 16,000,000 progeny ; at the end of two days 281,000,000,000 ; while at the end of the tliird day it would have reached the enormous number of 46,000,000,000,000. Such figures are at first thought very startling, and if this multiplication could go on unhindered, the earth might soon be dominated by micro- organisms. There are, however, many circumstances which constantly oppose them ; one of the chief of these is their own delicate susceptibility to change of environment, the slightest difference in the soil, amount of oxygen, temperature, or moisture being sufficient in many instances to arrest their growth or completely destroy them. Various species are found growing together, but the struggle for ex- istence and of natural selection is as active here as elsewhere 5 the stronger and more vigorous soon destroy the weaker. When they enter healthy living bodies they are attacked by the phagocytes and destroyed, or they do not find a congenial soil in which to grow, and either die or are swept out of the body by the excretory organs. The sjyore possesses an exceedingly dense enveloping membrane, which protects it from harmful external influences until such time as it finds a soil and environment suitable for its growth and propagation. The iDarent cell is usually enlarged at the middle or at one end by the growth of the spore, and when it reaches its full development gelatinous softening of the cell-membrane takes place, the cell breaks up, and the spore is set free. The spore loses its tough enveloping membrane during its process of development, and is therefore more readily destroyed. The struggle for existence between certain species of bacteria found growing together suggested a therapeutic principle, the overcoming of one pathogenic species by the introduction of another, which many investi- gators have been trying to utilize for the benefit of mankind, though as yet with only loartial success. Blood-serum therapy, however, is making rapid advances, and gives promise of being the most successful method of preventing or curing those diseases which are due to the introduction of micro-organisms into the system, or of their poisonous products. The growth of bacteria is also influenced by the presence of their own excretory or waste products ; for instance, the yeast plant ceases to grow after a certain amount of alcohol has been formed. The ammoniac fermentation of urine ceases when the ammonium car- bonate reaches thirteen per cent. (Fliigge. ) In lactic acid fermentation the process ceases when the acidity has reached 0.75 to 0.80 per cent., and the micro-organism is often destroyed by the action of the acid which has been produced. Lactic acid fermentation of the carbohydrates takes place spontaneously in milk, in the juice of the sugar-beet, in the accumulations in the oral cavity, etc., and may be artificially induced by a large number of different bacteria in saccharine solutions. (Miller. ) Acids and cdMlies possess a certain amount of controlling influence in the growth of bacteria, especially the former. Acids in very dilute solu- tion retard the development of bacteria. There are, however, important exceptions to this rule, as, for instance, the Mycoderma aceti — acetic acid J'lrt^ellateii ^pinllse aiKi vihno. , 21G0. / ^;>x.\' Fig. 289.— Bacillus of hog cholera. (V. A. Latham.) x 1000. a- ^ ^ 4^ ^^ Fig. 240.— Staphylococcus pyogenes. (V A. Latham.) X 1000. Fig. 241. — Streptococcus pyogenes. ;< 1000. 4>.%^ Fig. 242.— Streptococcus hominis. (V. A. Latham.) X 218.75. BACTEEIOLOGY OF THE MOUTH. 91 bacterium — thrives best in a solution containing an excess of from one to two per cent, of acetic acid. Ten per cent, of acetic acid prevents tlie continuation of the acetic acid fermentation, while the Micrococcus urea thrives best in a high degree of alkalinity. With few exceptions, how- ever, a neutral medium is best adajDted for the growth and propagation of micro- organisms. Heat and Moisture. — Two conditions are absolutely necessary for the germination and develoj)ment of bacteria, — viz., a certain amount of heat and moisture. Both must be present, and in suitable amount ; the requi- site amount of heat minus the moisture, or the moisture minus the heat, is in neither case favorable to their development. This is eminently true in the treatment of dental caries and devitalized teeth ; with thorough desiccation of the properly prepared cavity of decay, or of the root-canal, and the prevention of the ingress of moisture by tight plugs, caries will be arrested in one case and suppuration prevented in the other. In no department of surgery is thorough antisepsis more imj^ortant than in operations upon the teeth. The temperature necessary for the growth of the majority of bacteria is 37° C. (98° F.). Mature bacteria cannot resist a temperature of 77° C. (170° F.). Most of them are destroyed when exposed to a temperature of 55° C. (131 F.), while spores have been known to resist 100° to 120° C. (212° to 236° F.). A temperature of 100° C. (212° F.), if main- tained for ten to fifteen minutes, will effectually destroy the most per- sistent of spores. Spores resist the action of germicidal agents to a much greater degree than the bacilli which produced them, doubtless on account of the tough membrane which envelops them. Spores which have gained access to the tissues of the body may remain dormant for years, and give rise to no untoward symptoms until aroused to activity by the presence of conditions — environment — which favor their development and multiplication. Fiitterer reports having found the typhoid bacillus in the gall-bladder years after the initial attack of tyx^hoid fever. Pyogenic or Pus Bacteria, — The pathogenic micro-organisms with with which the surgeon and the dentist has most frequently to contend are those which cause suppuration. The pyogenic bacteria by a specific action convert the inflammatory exudates, leucocytes, and the cellular elements of the tissues into pus. They are, therefore, termed pyogenic or pus bacteria. Of these there are several varieties, most of them of the globular or coccus form (Figs. 240, 241, and 242). The number of bacterial forms which have been fully identified as the exciting cause of surgical diseases is not large, yet the statement may be safely made upon the basis of our present knowledge, that all traumatic infective diseases can be traced to the specific action of certain micro-organisms which have gained access to the tissues of the body. Koch laid down certain laws which he thinks should be used as the crucial test in establishing the specific disease-iDroducing power of any 92 OPERATIVE DENTISTRY. given organism : 1, it must be found in all cases of that disease ; 2, it must be found in no other disease ; 3, it must appear in such quantity and be so distributed that all symptoms may be accounted for by its presence ; 4, the organism musfc be capable of being isolated from the diseased tissues and be grown upon some artificial culture-media ; 5, when injected into an animal it must be capable of reproducing the disease. In many instances all of these conditions cannot be fulfilled, yet when a certain form or variety of micro-organism is constantly present in a par- ticular disease, it is fairly good evidence that it is the specific cause of that disease, although we may not be able to cultivate it artificially. Pathogenic Mouth Bacteria.— To Professor Miller of the Univer- sity of Berlin science is indebted more than to any other bacteriologist for our knowledge of the mouth bacteria. This author has shown in his most valuable work, the '' Micro-organ- isms of the Human Mouth," that nearly all of the pathogenic and many of the non-pathogenic micro-organisms have been found in the human mouth. He has isolated and cultivated more than a hundred different species obtained from the human mouth, thus establishing the fact that this cavity is the receptacle and often the breeding-ground of a considera- ble number of specific micro-organisms, as well as the source through which infection of many serious and sometimes fatal diseases may take place. Among the more important forms of pathogenic micro-organisms which he found in the mouth may be mentioned the Micrococcus of sputum septi- ccemia, Bacillus crassus sputigenus, Staphylococcus aureus and albus, Strepto- coccus pyogeneSy Micrococcus tetragenus, the Pneumococcus of pneumonia, and many others. MOUTH BACTERIA PROPER. Six forms of micro-organisms which are common to almost every mouth, and termed by Miller "Mouth Bacteria Proper," have the peculi- arity that no culture -medium has yet been found upon which they can be grown. Miller has experimented in hundreds of ways to cultivate them, but without success. These are the LeptotJirix innominata, Bacillus tuccalis maximus, Leptothrix buccalis maxima, Jodococcus vaginatus, Spirillum sjndigenum, Spirochcete den- tium (denticola). The term Leptothrix buccalis was first used by Eobin, and has been ap- plied to almost every living organism that has been found growing in the mouth. Miller thinks it should be banished from all bacteriologic writings on account of the confusion which it creates. He objects, also, to the term Bacterium termo, as it has so often been misapplied, some authors classing every organism showing a slight contraction in the mid- dle as Bacterium termo. Leptothrix Innominata. — This term has been proposed by Miller for those bacteria growing in threads, whose biology is too little known to define their relation to other mouth bacteria, or to form a separate group with distinct characteristics. Fig. '213.— Leptothrix buccalis. (V. A. Latham.) X 193.75- * 1 ' -hSf Fig. 244.— Mouth bacteria. (R. K. Andrews. ) A, diplococci ; B, leptothrix buccalis. BACTERIOLOGY OF THE MOUTH. 93 This organism is found in every mouth, but in varying quantities, depending largely upon the personal habits of the individual. It occurs in the soft white deposits which accumulate on the teeth ; sometimes it appears in masses, at other times it will be sparingly found (Fig. 243). These masses, according to Miller, vary in size, and consist apparently of small round granules, from whose margins thin, more or less zigzagged thi-eads project. These granular masses form the so-called ''matrix of Leptothrix huc- ccdis,^^ and were formerly looked upon as its spores, but are in reality partly micrococci and partly only crossings of the threads themselves. The threads vary considerably in length, and are from 0.5, a to O.S/j. broad ; they are twisted, tortuous, immotile, and inarticulated, and take a faint yellow stain with iodine. They often appear degenerated or even lifeless. Shorter threads or rods are also found which may be either frag- ments of the threads or young cells (Fig. 244). Bacillus Buccalis Maximus. — This organism is the largest occurring in the mouth. The threads measure from 30 to 150/^ long, the separate rods are from 2 to 10, a long and from 1 to 1.3 m broad. Miller found it in isolated threads, but most often in tufts, the threads having a ^^^- ^'^^^ parallel direction, separate bun- dles sometimes crossing each other. The rods have a very regu- lar contour, and are usually of the same thickness throughout (&, Fig. 245, is an exception). Iodine stains the majority of the threads brown-violet, either throughout or in isolated sec- tions. Miller has never found them in the dentinal tubuli ; their size would not permit their en- trance. Its size, the distinct and regular articulation of the rods, the absence of the zigzag windings, and its reaction to iodine, Miller thinks should preclude it from being classed with the Lejytoihrix innominata. Leptothrix Buccalis Maxima. — Miller has given this name to a form of Leptothrix threads which he found in the mucous deposits upon the teeth. He describes the organism as having long, thick, straight or curved filaments, which show a marked resemblance in form to the Bacillus huc- calis maximus just described, except that the joints are somewhat shorter in the latter. It does not give the iodine reaction. For these reasons he does not feel sure whether it is a different variety or the immature cells of the same variety in which the substance which takes the blue color is not yet formed. Jodococcus Vaginatus. — This organism is found almost universally in unclean mouths. Miller has never failed to find it except in two in- Bacillua buccalis maximus. solution. After treatment with iodine ISOO : 1. 94 OPERATIVE DENTISTRY, stances of children, aged respectively five and six years. He describes it as appearing singly or in chains of from four to ten cells, longer chains rarely being seen. They are of coccus form ; the cells appear sometimes as flat disks, or rounded or even square-shai3ed bodies, being enclosed in a sheath. The chains have a diameter of 0.73 //-. He occasionally found chains from which one or more cells were missing, others whose sheaths had burst, but from which the cells had not as yet escaped. The sheaths do not show the iodine reaction, but remain colorless, or after continued action of the re- agent become yellow. The cell contents always take the stain, the shade varying from dark blue to violet. Spirillum Sputigenum. — This bacterium is present in all mouths, but in varying quantity. In cleanly mouths the numbers will be small, in those which are foul from neglect they often exist in prodigious numbers. They are found in the soft deposits at the margins of the gums. In neg- lected mouths with inflammation of the gums Miller sometimes found an almost pure culture of the organism. It is comma-shaped in form and has very active spiral movements, and when grouped together it forms short 8j)irals or S-shapes, It is sometimes found in the dentinal tubules. It was for a time thought to be identical with the comma bacillus of Koch, — the cholera bacillus, — but Miller has proved it to be an entirely different species, from the fact that it cannot be artificially cultivated upon any known culture medium, while the Koch bacillus can be readily cultivated. Klein, however, has stated that the Spirillum sputigenum can be cultivated in acid gelatin. Miller discovered and describes two other forms of curved rods or comma bacilli which he found in the human mouth. The iirst is not difficult to cultivate, and occurs in short, plump, tapering rods, slightly curved and generally united in j)airs. It is motile and multiplies by fission. The second occurs in the form of delicate rods of varying length, some- times straight, at others so curved as to form the arc of a circle, and when joined together at their ends forming a circle or letter O ; occasionally they are so joined as to form a letter S. They are non-motile, and multi- ply by fission, and during this process they form chains of cocci. This organism possesses many of the characteristics of the Finkler-Prior ba- cillus, but whether it is identical has never been determined. Spirochaete Dentium (deDticola). — Miller found this organism (Fig, 246) almost universally present, not, however, in decaying dentin, but in the same locations as the Spirillum sputigemmi^ — namely, at the margins of the gums, in the deposits found there, especially when the gingival bor- ders are in an inflamed condition. This organism is of spiral form, from 8 to 25 A long, of unequal thickness, very irregular windings, and with marked differences in their susceptibility to staining reagents. Miller is not sure whether they are two separate organisms, or only different stages in the development of the Spirillum sputigenum. In Fig. 247 it will be noticed that the same spiral or comma-shaped bacilli have flasfellse. Fig. 24<).— Spirochseta dentium (deiiticola) and leptothrix threads. : < 1000. ITlG. 247. — Spirochseta dentium (denticola), showing their fiagella. :< 1000. Fig. 248.— Leptothrix gigantea, from dog. 750. Fig. 219.— LeptothriN; gigantea. (V. A. Latham ) 1000. Fig. 250.— Leptothrix gigantea. (Miller.) 1000. BACTERIOLOGY OF THE MOUTH. 95 Leptothrix Gigantea. — This very remarkable organism (Fig. 248) was found by Miller in the mouth of a dog suffering from pyorrhoea alveolaris, and to which he has given the above name, suggested by its enormous dimensions. It grows in tufts or fascicles whose threads diverge from a common point of adhesion (Fig. 249). It forms cocci, rods, and threads, and therefore belongs to that group of bacteria known as pleomorphic, having more than one form. The threads of the individual tufts vary considerably as to their thickness ; some are very thin, others very thick. They sometimes appear straight (Fig. 250), at others irregularly curved or twisted into spirals. He did not determine its etiologic relations to the disease. In exam- ining the mouths of other animals — sheep, cattle, pigs, horses, dogs, cats, rabbits, etc. — he frequently found leptothrix-like fungi. Besides these micro-organisms, there are a very great number of others that are found at different times in the human mouth, many of which are pathogenic. Miller has made the estimate that in a certain very unclean mouth there were not less than 1,140,000,000 of micro-organisms. With such conditions as these it is not surprising that the human saliva is poisonous and sometimes possessing very virulent toxic properties, which may endanger the life of the operator who should be so unfortunate as to become inoculated with it through some wound or abrasion upon his hands. Biondi isolated from the human saliva five different forms of pathogenic micro-organisms, to which he gave the following names : Bacillus salivarius septicus, Coccus salivarius septicns, Micrococcus tetragenus, Streptococcus septo- pycemicus, and Staphylococcus salivarius pyogenes. Cultures of all of these organisms were found to be more or less virulent, causing death in mice and guinea-pigs in from twenty-four hours to fifteen days when injected subcutaneously. Miller has also found within the mouth a considerable number of other bacterial forms possessing pathogenic i^roperties, four of which he exam- ined in detail and named as follows : Micrococcus gingivce pyogenes, Bacte- rium gingivce pyogenes, Bacillus dentalis viridans, and Bacillus pulpce pyo- genes. The first and second were found in the pus from pyorrhoea alveolaris ; the third was found in decaying dentin, and the last in gangrenous pulps. Cultures made from the first two and the last were found to be ex- tremely virulent, causing death, when injected into the abdominal cavity of white mice, in from ten to twenty-five hours. The Bacillus dentalis viridans was not quite so virulent as cultures from this organism. When injected into the abdominal cavity of mice and guinea-pigs it produced death from peritonitis in from twenty-two hours to six days. Black, in his investigations of the mouth bacteria, found that the pyo- genic or pus-producing organisms were almost constant in this location, and says, " We must take into consideration the fact that the pyogenic bac- teria are generally present in the oral cavity, and endanger every wound we make in it." 96 OPERATIVE DENTISTRY. Miller, in giving emphasis to the fact that the mouth, loaded as it is with so many forms of jpathogenic micro-organisms, is a prolific source of infection, says, "The diseases caused by the pathogenic bacteria of the mouth may be considered under six heads, according to the point of en- trance of the infection : "1. Infections caused by a breach in the continuity of the mucous membrane, brought about by mechanical injuries (wounds, extractions, etc.). These lead either to local or general disturbances. "2. Infections through the medium of gangrenous tooth-pulps. These usually lead to the formation of abscesses at the point of infection (absces- sus apicalis), but also sometimes to secondary septicaemia and pyaemia, with fatal terminations. "3. Disturbances conditioned by the resorption of poisonous waste products formed by bacteria. "4. Pulmonary disease caused by the inspiration of particles of mucus, small pieces of salivary calculus, etc., containing bacteria. "5. Excessive fermentative processes and other complaints of the di- gestive tract, caused by the continued swallowing of microbes and their poisonous products. "6. Infections of the intact soft tissues of the oral and pharyngeal cavities, whose power of resistance has been impaired by debilitating dis- eases, mechanical irritants, etc." Dr. Filandro Vicentini, in a series of articles published in the Inter- national Journal of Microscopy and Natiiral Science (1894-1895), upon the "Bacteria of the Sputa" and the Cryptogamic Flora of the Mouth,'' an- nounces the discovery of a thread-like organism or Leptothrix, which he terms Leptothrix racemosa. This organism he first found in the sputa of 13ertussis, and afterwards traced to the mouth as its natural habitat, and which could always be found in the patina dentaria, — plaques of deposit, — located in the interdental spaces, if the material were gathered in the morning before the fast was broken, or some hours after a meal. This organism differed from the various forms of Leptothrix which had been recognized and described, in that the stems or filaments present a beaded appearance, and that these stems terminated in enlargements or heads which contained six or more rows of spores, as shown in Plate VI., Fig. 24. This micro-organism, he claims, passes through four jyliases of develop- ment and is therefore pleomorphic. The first phase being common to all the other species of bacteria, but which does not, however, represent its whole cycle of life, but only its primordial stage of immersed vegetation, or a vege- tation destined to propagate in a liquid or semi-solid media. In the second phase of the life history of the organism many degrees of transition may be observed. These are represented ' ' by chains, bun- dles, and masses of intertwined filaments, isolated filaments, large dumb- bell bacteria of the type p, p, and y, Plate V., and masses of diplococci ; the large dumb-bell bacteria being derived from the diplococci, the two original cocci linking together. The chains are often surrounded by masses of diplococci, while in the same chain small diplococci may alter- ^ x^ C3 ^'I'j o «^' o 1 ' ^ ro Oi PLATE VI. f<^\ Fiq.IJ iJ/jioa [, 1X1700 ^> Q[tprr.Yiarc[ilini.deL BACTERIOLOGY OF THE MOUTH. 97 nate with elliptical bacteria and medium-sized dumb-bells, all perfectly equal, which form the largest number." The third phase is generally met with in the salivary calculus of the teeth. Its predominant elements are large filaments, often long, bent, and reunited in bundles, and stumps. Two notable features are observed in the large filaments, which have not been described by any previous author. The first of these is the division of the radial extremity of the filament into two or three branches (Plate VI., Fig. 9). " In a the filament is broken towards the top and exhibits two long roots ; in h there are three hood-shaj)ed roots, both appearing to be swollen at their ends (c) like haustoria.^'' The author raises the query of the use of these barbs or roots, if they are not to obtain a firm foundation in the soil. And to what purpose a firm foundation, if not to support higher forms of vegetation ? The second feature is that of the enlargement or ''swelling of the ter- minal ends of the filaments, as shown in & and c, Fig. 9, and these are of varied form, at times containing a kind of nucleus. Plate VI., Fig. 26, a and &, show further development into heads or ears. There are other en- largements found along the filament, which might be styled knotty. "Intermixed with the other element — the stumps — are almost all the forms of bacteria, bacilli, spirilla, etc., besides a large number of very varied small chains, after the types shown in Plate V., c, d, Jc, i, x, and a/." The large size of the stumps he thinks may be accounted for by the fact that "the points of the filaments are removed by friction or other mechanical means, and this seems to impart a greater develoj)ment to the remaining stems in the sense of greater thickness, as happens in the pruning of trees, through the retrocession of the ascending sap." This he thinks explains "the appearances of the stumps and their fragments, which are so various, and which led Miller to make of residual filaments two distinct species, — viz., Leptothrix huccalis maxima and Bacillus hiccalis maximus, while the fertile filaments which he had discovered constitute Miller's third species, the Leptothrix innominata.^^ "From the tiny islands of the stumps ia question spring at last the fructifications. The larger filaments gradually become thinner and pale, showing in their interior countless granules or parietal gemmules. These are the fertile filaments. They may spring either from the proper fila- ments with continuous contour or from the little chains, d, Plate VI., Fig. 9, which are seen occasionally on the top of those filaments ; and in this last case, instead of a gradual thinning, may abruptly pass from the chain to the fertile filament," as shown in the figure. This phase the author terms incomplete aericd vegetation. The, fourth phase he ievm^ complete aerial vegetation or fructification. In this stage the fructification heads or ears have reached a developmental stage, which shows the formation of spores arranged in three rows (Plate VI., Figs. 10 and 13). ' ' The fertile filaments are sometimes straight, at others bent or curved ; occasionally they are entirely wanting, because the fructifications have been carried away by mechanical force." 7 98 OPERATIVE DENTISTRY. In Plate VI., Fig. 10, at a, a, ''gemmules of reserve" are seen adhering to the walls of the stem ; at h the little spores are properly lodged ; at h' only- five are seen, the others having dropj^ed ; at c the penultimate articula- tions of the stalk appear older and woody ; the last is granular, like the two articulations on the apex of the younger filament, d. The sporules, which are very small and round, are arranged in three vertical rows ; this is the appearance, almost without exceiDtion, in all the specimens observed, hence it is inferred by Yicentini that they are ar- ranged in six longitudinal lines. In several specimens stained with picric acid the iDrolongations of the stem into the interior of the fructification head could be distinctly traced. Staining with aniline colors rendered the viscid substance in which the sporules are suspended opaque ; but if glycerol was substituted for water in the preparation of the slide, the stalk after a long time reappears distinctly in all its length. The stalk and the ear form a continuous whole, and he likens a tuft of the organism with its vibrating ears to '' a field of wheat." The length of the ears is frequently considerable, as shown in Plate YI., Fig. 16, the more conspicuous specimens being found in pulmonary sputum, ' ' the largest being one-sixth of a millimetre. ' ' Bacteria in general are reproduced by two methods, — viz., hj fission or cell divisions, and by the formation of spores within the parent cell, termed endogenous spore formation. Another method of reproduction is known as arthrosporous reproduction. By this process spores are formed out of portions of the cell-body, or some of the individual cells of the latter set free from the parent organism, the opposite of endogenous spore formation. Yery little is known of this process at the present time. Still another method of reproduction may be mentioned : this is termed acrogenous abjunction, a process by which spores are formed at the apices of certain cryptograms. In this process the terminal cell becomes en- larged and transformed into what is known as a hasidium, — a diminutive base, — from which external sprouts or sterigmata, bearing spores or sperma- tia upon their terminal ends, arise. Yicentini believes from his study of the Leptothrix raoemosa that it propagates by two distinct methods, the first by " internal gemmulation,^^ — endogenous spore formation, — which he terms the "inferior or first cycle," and the other by " conjugated fructification,^^ — acrogenous abjunction, — which he terms the "superior cj^cle." He claims that "the organism possesses real organs of reproduction by which it would resemble fungi and dioecious algce, with distinct sexes upon different filaments or individuals. Its fertile filaments are at times engrafted, with two or three roots, upon clods or firm substrata, and end in fructification. The ears are linked together and fastened to a stalk, as shown in Plate YI., Fig. 16. Other fila- ments, however, less numerous than these, at times multiply, and lastly, branching off, bear certain j)roductions by points, the male elements (Plate YI., Fig. 14) or pseudo-inflorescences or blossoms formed of spindle-like {d, Fig. 14), snake-like, or comma bacilli {Spirillum sputigenum), destined from all appearance, through their lively activity, to the function of con- jugation. BACTERIOLOGY OF THE MOUTH. 99 This investigator was able to observe the complete process of fructifi- cation of the organism in sputa impregnated with its elements. The process is completed upon the fourth day by keeping it well sheltered in the dark. Yicentini makes the bold statement that he believes, from a study of the various phases through, which the LeptotJirix racemosa passes in its life his- tory, that it is with perhaps one excejDtion the mother organism of all the bacteria and bacilli found in the sputum. He says, "Of the six primary species of fungi of the mouth, described by Miller, there would, in fact, exist only one, the Leptotlirix huccalis of Eobin (Leptothrix innominata of Miller), or at most a second one, the Si^irillum (Spiroclicete dentium of Miller). The other four types would represent, if we are not mistaken, only phases, or disintegrated i)articles of the microphyte, — viz., Bacillus buccalis 'maximus and Leptotlirix huccalis maxima, fragments of the stumps that form the inferior layer of vegetation : the Jodococcus vaginatus series of special sheaths of bacteria proceeding from certain 'gemmules of re- serve, ' enclosed in the filaments ; the Spirillum sputigenum (comma bacilli) with our spindle-like and serpentine appendages detached from the pseudo- inflorescences (blossoms), and probably male organs. "All these particles or articulations cut from the mother plant (except the last, — viz., the copulative filaments) multii^ly by themselves, in va- rious ways, according to the condition of the nutrient substratum, in the liquid menstrua or on firm soil." He further suggests, as have some other investigators, that the patho- genic or virulent properties of bacteria are in all probability acquired as a result of their environment, and that it is not necessarily a permanent quality. This may exj^lain the periods of activity and of immunity which are observed in relation to the progress of dental caries. Dr. J. Leon Williams, in an article in the Dental Cosmos (April, 1899) upon the "Bacteriology of the Human Mouth," states that he, without knowing of the discovery of Yicentini, had some two or three years later made an identical discovery of the fructification of Lei^tothrix threads. He says, "While studying mouth bacteria I came across very regular arrange- ments of coccus forms about the ends of Leptothrix threads. At first I re- garded these as purely accidental. But the persistence and regularity of these forms in nearly every one of the preparations I was then making led me to examine them more closely, and I was astonished to find what appeared to be a thorn-like connection between the spore or coccus form and the leptothrix-like thread." After reading the work of Yicentini, which was brought to his atten- tion by a friend to whom he had mentioned his own discovery, Williams went forward with his work. His method of j)rocedure is as follows : " A stream of sterilized water is thrown from a iDOwerful syringe into the inter- dental space between the first and second upper molars. With a sharp, sickle-shaped instrument, previously sterilized, a gelatinous microbic plaque is removed, which appears upon the instrument as small, grayish- white material, which possesses considerable tenacity. This is placed 100 OPERATIVE DENTISTRY. upon a clean watch-glass and covered with twenty or thirty drops of a thin, watery solution of methyl violet aniline, the mass being allowed to remain in the solution for twelve hours, but in the mean time occasionally teasing it apart to obtain a better penetration of the staining fluid. The fluid is then drained off and the mass washed first with sterilized water and then with a mixture of equal parts of glycerol, spirit, and water. A drop of the same mixture is then placed upon a cover-glass, the stained mass dropped into it, and teased apart as much as possible, and then care- fully inverted on a slide, care being taken to make as little pressure as possible upon the cover-glass. The preparation will now show fields sim- ilar to Figs. 251 and 252 if examined with a one-sixth-inch objective. Under a one-tenth- or one-twelfth-inch objective in fortunate specimens, fields like Fig. 253 will be observed. Such a view very clearly resembles a grass-plot, from which arise the blossom, fruit, or seed-heads of the plant. These are the fruit or spore-heads of a thread-like micro-organism, which I have found to be as constant as any form of bacteria in the human mouth." The Leptothrix racemosa of Yicentini (Fig. 254) shows such a field under high magnification. This organism Yicentini describes as having ears or fruit-heads made up of six regularly arranged rows of spores or seeds. Williams has se- cured a few lucky views of the heads in cross-section, which show them to be composed of twelve rows or even more. The attachment of the spores to the central stalk by the thorn-like processes, sterigmata, or peduncles, and which constitutes the final and irrefutable proof of the correctness of Yicentini' s claim of the fructifica- tion of the Leptothrix racemosa, is most beautifully shown in Figs. 255 and 256, while in Fig. 257 the spore attachment in both longitudinal and trans- verse section is likewise finely shown. Fig. 258 shows a transverse section under a magnification of about nine thousand diameters. Williams believes with Yicentini that the organism is one of very rapid growth and common to all mouths, and the forms which must result from the breaking up of the spore heads and stem of the organism are Jong and short rods^ various sizes of micrococci, various sizes of diplococci, and various sizes of curved and clvh-shaped hacillL He further says, ^ ' I have no dispo- sition to indulge in speculation over these discoveries, but here are the facts which must be reckoned with in all future considerations of the bac- teria of the human mouth and body. It would be folly to deny that these facts are big with possibilities. . . . However much we may be disposed to reticence, it is imi)ossible to avoid asking what becomes of the enormous number of micro-organisms of different forms and sizes which are being constantly shed into the human mouth by this parent organism, and how many of them have been classified as x^ermanent si)ecies." TJj)on this j)oint Yicentini says, " According to my calculations not less than from two to three hundred trillions of germs or separated ele- ments are generally present in the mouth and nose, liable to disseminate the species at every minute into other parts." There is a question, however, whether these organisms are not placed in the mouth by nature for a beneficent purpose. Fabulous numbers of Fig. 'iol. — The material from which this photograpli was made, and all of those which follow, was obtaiued by scraping the approximal surfaces of teeth after thoroughly syringing with sterilized water, and, in some instances, also after rubbing the surface of the tooth with a wad of sterilized cotton-wool. The gelatinous mass of micro-organisms adheres to the surface of the enamel with considerable tenacity. The scrapings were stained with watery solution of gcntian-violet-anilin water and mounted m diluted glycerol. Under a power of four cr five hundred diameters places will be found presenting such appearances as are shown above. (T. Leon 'Williams.) Fig. 252.— Frnctification heads of hptothrix racanosa. Zeiss objective :', mm., ])rojection ocular 3. (J. Leon Williams.) Fig. 2b'i. — Fructification heads of leptothrix racemosa. (J. Leon Williams.) Fig. 254.— Thick growth of leptothrix racemosa fructification heads from approxinial surface of tooth, under high magnifying power. (J. Leon Williams.) Fig. i.Vi.— Fructitication beads of Uploihrix raccmosn. Fig. 2n6. — Fructification heaiis of Irptntlnix rncemosd. Fig. 257. — Showing attachment of spores to central stem in both longitudinal and transverse section. (J. Leon Williams.) Fig. 258. — This photograph is from au enlarged negative made from an original photograph of trans- verse section of fructification head of leptothrix racanosa. The original negative was magnified to 2000 diameters. The enlarged negative and the above print represent an amplification of about 9000 diameters. It shows the cell wall and the shrinkage of the protoplasm caused by the action of the glycerol and spirit. The spore-stems, or sterigmata, are seen to arise from the central protoplasm and to pass through the cell wall. (J. Leon Williams.) BACTERIOLOGY OF THE MOUTH. 101 them are constantly passing into the digestive tract, where they may, as suggested by Hallier, take an active part in the transformation of the in- gested food by the transmutation of the starchy elements into glucose, both in the mouth and the stomach. Miller and others have recognized in the buccal bacteria a peptonizing action equal to pepsin itself, even with- out the action of acids. BACTERIA WHICH AFFECT THE INTEGRITY OF THE DENTAL TISSUES. The zymogenic and the saprogenic micro-organisms have also a distinct interest for the dental surgeon from the fact that certain species of the zy- mogenic bacteria have for their special function the formation of acids within the mouth by the fermentation of the carbohydrates which are lodged there as alimentary debris, and also that certain other species of the saprogenic bacteria have the power of liquefying albuminoid sub- stances or digesting them by the production of a soluble ferment. According to the now generally accepted theory of dental caries, these micro-opganisms are the j)rime factors in the production of this disease. The fermentation of the carbohydrates within the mouth is produced by certain species of bacteria, the results of which are the formation of various compounds, lactic acid, mannite, dextrin, etc. According to Miller, butyric acid is never found in the mouth except as a by-product in lactic acid fermentation. The fermentation of the carbohydrates is chiefly productive of the formation of lactic acid ; this is brought about by certain species of bac- teria acting upon these fermentable compounds and converting them into lactose and lactic acid, with or without the evolution of carbon dioxide. (Miller.) A considerable number of micro-organisms are capable of affecting this transformation. Miller, experimenting with twenty different species of mouth bacteria upon the carbohydrates, obtained in sixteen of them an acid resultant, while in one of the others, which was found in a putrid pulp, the evolu- tion of gas was so copious as to tear the gelatin into shreds. Vignal found, in his researches upon the mouth bacteria, that out of seventeen different varieties, seven of them liquefied coagulated albu- min, five others caused it to swell and become transparent, ten dissolved fibrin, nine dissolved gelatin, seven coagulated milk, six dissolved casein, three transformed starch, and nine converted lactose into lactic acid ; the majority, it will be seen, had a i)eptonizing effect, and some of them grew indei^endent of free oxygen. The jprincipal organism, however, in the production of lactic acid, and one which is constantly found in the human mouth, is the Bacterium acidi lactici of Huepj)e. Among the carbohydrates which are most highly fermentable and readily acted upon by the lactic acid bacterium are the sugars, dextrin, starch, cellulose, etc., and these are always found in the mouth, in greater or less quantities, as alimentary debris^ ready to be acted upon by zymogenic 102 OPEEATIVE DENTISTRY. bacteria. The mouth presents at all times the necessary degree of heat and of moisture for the rapid growth of these organisms. Lactic acid in very dilute solutions readily acts upon the inorganic substances of enamel structure and disintegrates it, and thus opens the way for caries to attack the dentin. The organisms which i)roduce lactic acid enter the dentinal tubuli, where they continue to generate acid, which removes the calcium salts, while the liquefying or peptonizing action of other forms of bacteria dissolve the decalcified dentin matrix. Several other fermentations of carbohydrates take place within the mouth, by which mannite, dextrin, etc., are formed. Mannite is the product of a fermentation induced by an exceedingly small coccus — Micrococcus viscosus — which grows in chains in various sac- charine beverages, in wine, beer, etc., and in saccharine juices (Miller), and forms a gummy product known as mannite. Black believes that this substance is the cause of sordes which accumulate upon the teeth in the continued fevers, and that it may be the cause of thick, ropy saliva. Dextrin is formed as the result of fermentation caused by the action of a micrococcus — Leuconostoc mesenterioides — upon beet-juice and molasses, and can be induced artificially in saccharine solutions. (Miller.) Action of Pathogenic Bacteria. — The question of how the xmthogenic hacteria i^roduce their effects u])on the living tissues of the body is one ux)on which there is still a wide difference of belief. Some observers are of the opinion that the symptoms of infectious diseases are the result of the for- mation by the micro-organisms of chemical substances of an irritating or poisonous nature, a sort of si^ecific excretia. Others believe the phenomena, both local and constitutional, to be due to changes wrought within the tissues by the organisms themselves during their develoi^ment, and that it is not necessary to assume the formation of a specific x^oison or virus to account for these phenomena. The action of the pyogenic or pus-producing bacteria is to produce local irritation or inflammation, while the chemical substances elaborated in the focus of infection are disseminated throughout the body, which, by virtue ot a i:)eculiar action, thought to be ferment-like, augments tissue metamorphosis, stimulates the "thermic centres" and thereby increases the body temperature, producing fever or systemic disturbance. This condition is known as septic infection. The absorption of ptomaines without the presence of pathogenic bacte- ria will produce grave systemic disturbances. This condition is termed septic intoxication, or toxic infection. Ftomaines are powerful animal poisons developed by the process of de- composition of animal tissue in the presence of saprophytic bacteria. In their physiologic action they resemble the alkaloids, and when received into the circulation by the process of absorption they produce more or less severe constitutional symptoms. The ' ^ toxines' ' probably belong to this class of substances. The develoi^ment of the ptomaines seems to exert a controlling or in- hibitory effect upon the growth of the micro-organisms. Many of the artificial cultures of bacteria, after a period of growth, cease to develop, BACTERIOLOGY OF THE MOUTH. 103 and it is partly by virtue of the formation of these substances that this controlling effect is brought about. Leucomaines are animal alkaloids which are produced within the living tissues by metabolism — tissue changes — independent of micro-organisms. The pathologic significance of these products is as yet not well defined. Immuniiy. — The effects of the virus of certain bacteria upon the vital fluids and the tissues of the body in certain diseases is to give protection against future attacks ; in other words, to render the organism immune. Pasteur believed this protection or immunity to be due to the ex- haustion of the chemical substances supi^osedly necessary to maintain the life and development of the siDCcific bacteria. Fraenckel was of the opinion that the first invasion of the bacteria left behind certain substances which were inimical to the further development of the same species of micro-organisms, which might at some other time gain an entrance to the system. From the foregoing pages it will be readily appreciated that the diffi- culties to be surmounted in securing an aseptic condition of the mouth are so great as to make it an imj)ossibility. Much can be attained, however, by a scrupulous attention to certain hygienic rules, — viz., brushing the teeth after each meal, followed by the use of floss-silk passed between the approximating surfaces, and the assid- uous use of antiseptic mouth-washes. Boric acid in fifty per cent, solution, cinnamon water, formal (one per cent.), listerine, pasteurine, and borolyj)tol are all valuable antiseptics for this purpose. Too much care cannot be exercised by the dentist and the surgeon in thoroughly cleansing the mouth and the teeth before commencing any operation which involves a breaking of the continuity of the soft tissues. and the thorough sterilization of all instruments and dressings used in the operation. A no less important precaution is that of thoroughly cleansing the hands and finger-nails of the oj)erator, and washing them in antiseptic solutions. Failure to do this often results in the introduction of pyogenic bacteria and establishing suppurative processes, which with proper care might have been avoided. STERILIZATION OF HANDS AND INSTRUMENTS. Absolute cleanliness in all operations within the mouth is of such great importance from the surgical stand-point that too much stress cannot be laid upon its strict observance in every detail. This comprehends the steril- ization of the hands of the operator, of the mouth and teeth of the patient, of the instruments used in the operation, of the rubber dam, and of other materials employed for the exclusion of moisture. The student who would be successful in the treatment of the diseases and injuries to which the teeth and the mouth are subject must be taught to appreciate the value of antisepsis and the technique of its employment. Carelessness upon the part of the operator in not observing the ordi- nary precautions of aseptic methods may not always result in sprea'ding infection ; but this is due to the resistance of the tissues which have been 104 OPERATIVE DENTISTRY. thus endaugered, rather than to a lack of transmitting infectious material. Cases are on record in considerable numbers in which serious consequences have followed the employment of unclean or septic instruments in opera- tions like lancing an alveolar abscess, extracting a tooth, etc., some of which have resulted fatally. Among the most common infectious diseases which may be transmitted from one patient to another by the hands of the dentist and of his instru- ments are tonsillitis, dij^htheria, suppurative inflammation, certain forms of stomatitis, malignant oedema, tuberculosis, and syphilis. In view of these facts, the operator should exercise the greatest circumspection in the cleansing and sterilizing of his hands and instruments when passing from one i^atient to another. The operator should never under any circum- stances x^ermit himself to come in contact with his patient without first washing his hands, and this should be done in the presence of the patient, that there may be no lingering doubt about the question of cleanliness ; while the instruments which he is about to use should be taken fresh from the instrument- case, where they have been placed after being sterilized. Instruments should never be permitted to remain upon the operating-table after the patient has been dismissed, but should be immediately cleared away and placed in the sterilizing api)aratus before the next patient takes the chair. Such attention to the appearances of cleanliness is very gratify- ing to the scruples of patients, and increases their confidence in their dental adviser that no effort will be lacking upon his part to insure them against the spread of disease by infection. TECHNIQUE OF STERILIZATION. Sterilization of the Hands of the Operator. — This may be accom- plished by thorough washing and scrubbing with hot water and antiseptic soap ; green soaj) containing two per cent, of carbolic acid is the best for this purpose. The finger-nails should then be carefully cleansed and the hands again washed in hot water. In cases of operation in which the soft tissues are to be involved the hands should receive a bath in a five per cent, solution of carbolic acid, or a 1 to 1000 solution of mercuric bichloride. The operator should also guard against his own infection by covering even the slightest abrasion of the cuticle of his hands with a film of flexible col- lodion. Sterilization of the Mouth and the Teeth of the Patient. — This comiDrehends the thorough removal of all calcareous and other deposits upon the teeth ; the filling of all carious cavities, either permanently or temx^orarily ; the treatment or removal of all suppurating teeth and roots, and a liberal use of antiseptic mouth- washes, like a saturated solution of boric acid ; two to three per cent, solutions of carbolic acid ; the Thiersch solution (salicylic acid 4 parts, boric acid 12 parts, water 1000), or solutions of listerine, borolyptol, pasteurine, or formol 1 to 100 of the forty per cent, solutions. Complete sterilization of the mouth and teeth, however, can never be attained by even the most rigid technique, but it may be so nearly approxi- BACTERIOLOGY OF THE MOUTH. 105 mated as to greatly reduce tlie dangers from infection in those cases \yliere the continuity of the soft tissues of the patient has to be broken. Sterilization of Instruments. — Instruments of every kind should be thoroughly sterilized before being used upon a patient. This may be most efficiently done by boiling in water. All instruments which have been used Fig. 259. Instrument sterilizer. about the mouth of a patient should first be thoroughly scrubbed with warm water and soap, rinsed, and placed in a sterilizer and boiled for at Fig. 260. Dental mirror. least five to ten minutes. Fig. 259 shows a very neat and efficient steril- izer, manufactured by the S. S. White Dental Manufacturing Company, which is sold at so moderate a price that every dentist can afford to possess one. When the instruments are removed from the sterilizer they should be wiped dry with a clean, sterile towel while they are still hot. By this method the instruments will not rust or tarnish. Mouth-mirrors are some- times injured by the boiling x)rocess, but the best German makes stand 106 OPERATIVE DENTISTRY. the ordeal very well, and will often last for months. Ash & Sou and the S. S. Wliite Dental Manufacturing ComiDany supply a mirror (Fig. 260) which can be taken out of the frame, which makes it possible to sterilize this part of the instrument by placing it in strong solutions of carbolic acid, while the frame may be boiled. The safer method, however, is to boil these instruments like all others, and when the glass gives out replace it by a new one, which can now be done at trifling expense. Rubber dam may be kept in a sterilized condition ready for use by cutting it into squares of suitable size and placing it in a covered glass jar containing a 1 to 3000 solution of mercuric bichloride and washed in sterilized water before using. To guard against the possibility of carry- ing infection by the rubber dam from one patient to another it is best never to use the dam a second time, except upon the same jpatient. Gauze and cotton rolls are now prepared for the use of the dentist, which have been rendered sterile by prolonged heat. These should be kept in boxes with tight-fitting covers, and may be resterilized at any time by placing them in a sterilizing oven heated to 250° to 300° F. CHAPTER YI. EXAMINATION OF THE TEETH AND MOUTH. The imiDortauce of frequent examinations of tlie teeth, and oral cavity as a i^ropliylactic measure against the development of disease and its early discovery cannot be too strongly urged upon the public or upon the practi- tioner. The old adage '^ that an ounce of pFCvention is worth a pound of cure" was never of more value than when applied to the prevention of dis- eases of the teeth and mouth. It has been said that "the highest aim of the healing art is not to cure dis- ease, but to prevent it.'''' It should be, therefore, the highest duty of the dental surgeon to strive to prevent the development of disease within the oral cavity, and to check its ravages at the earliest possible moment, so that the attendant dangers may be reduced to the minimum. In order to accomx)lish this much-to-be-desired result frequent examinations at stated periods, with instruction in the various means which may be adopted to keep the teeth and mouth in an hygienic condition, will be absolutely necessary. This system of frequent x^eriodical examinations, to be most effective, should be instituted in early life, commencing with the little children as soon as the deciduous teeth are erupted. These examinations should be made as often as every three months in the case of little children. At these sittings the child should be taught by the dentist how to cleanse the teeth. This first instruction in the art may be rendered the more effective by the operator giving the child an object-lesson, by brush- ing his own teeth in its presence. The little patient should then be given a brush and induced to imitate the brushing process by watching the oper- ator as he applies the brush to the teeth and makes the necessary move- ments in order to cleanse all the surfaces that can be reached by this method. The nurse or the mother of the child should be present, and in- structed to follow up the teaching each day, adopting the same methods of instruction. By the frequent examinations indicated the dentist has opportunity to learn whether or not his instructions are being followed and the child keei^ing its teeth and mouth clean, and if not, it gives re- peated opportunities to correct the habit of neglect and impress upon the child and those who are responsible for its care the importance of a hy- gienic condition of the mouth in preventing the development of disease. In the light of the prevailing theory of disease, and of the constant pres- ence within the mouth of so many forms of zymogenic and pathogenic micro-organisms, the practitioner would be remiss, indeed, who did not impress upon his clientele the great value of a hygienic condition of the oral cavity as a i^rophylactic measure. 107 108 OPERATIVE DENTISTRY. At eacli periodical visit the teeth should be thoroughly cleansed and polished, and a critical examination made in reference to the presence of caries, diseased conditions of the gums, or other abnormal manifestations, appropriate treatment being instituted for the relief of the individual ail- ment. This system can be followed with older children, young people, and adults, the intervals between the examinations being longer or shorter according to the exigencies of each individual. Children and youths during the period of rapid growth, chlorotic girls, and pregnant women have usually an increased predisposition to dental and oral diseases ; consequently it is the duty of the dentist to acquaint them with the fact that they should give increased attention to the care of their teeth and mouth if they would maintain these organs in a healthful condition. The writer has found in his own x)ractice that his clients were very ap- preciative of this thoughtful attention to their physical welfare, and, as a rule, gladly co-operate with him in these endeavors. In order that no case requiring especial attention may be overlooked, it is his custom at the sitting given for the examination to record an engage- ment upon the appointment-book for the next examination, informing the patient that a notice of the engagement will be mailed a few days in ad- vance of the time when it becomes due. These engagements, it is pleasant to say, are usually kept with great X)unctuality and evident appreciation. POSITION OF PATIENT AND OPERATOR. In examinations of the oral cavity good light is a siiie qwi non. An examination conducted with inadequate light is of little value, and a diag- nosis made under such conditions would be unreliable. The patient should therefore be seated in a suitable chair provided with a head-rest capable of being raised and lowered and moved backward and forward. The head of the patient should be so positioned that when the mouth is opened the light will fall directly within it. The operator should stand upon the right of the patient, with his feet firmly planted, the body erect, and the shoulders thrown back. The chair should be so elevated that the operator can maintain this position during examinations, and as far as possible in all operations. The stoop- ing position so often assumed by many operators is not conducive to full and regular breathing, and sooner or later will result in stooping shoulders, contracted chest, and pulmonary complaints. The operator should always be careful to breathe through the nose. Habits which produce a bad breath should never be indulged in. The contact of the operator with the patient should be at as few points as pos- sible. People of refinement and Culture appreciate the efforts of the den- tist to guard them against any unnecessary contact of person. The dental chairs as made to-day are capable of such changes that the position of the patient can be suited to any requirement, so that the only contact that is necessary to support and guard the hands of the operator is that of resting EXAMINATION OF THE TEETH AND MOUTH. 109 the ends of the ring and fourth fingers upon some portion of the patient's face, while the fingers of the left hand control and guard the lips. Mouth-mirrors. INSTRUMENTS USED IN EXAMINATIONS. The instruments and appliances which are necessary to a thorough ex- amination of every x)ortion of the crown of each individual tooth are of several kinds, — viz., mirrors, magnify ing-glasses, explorers, electric mouth- lamp, floss-silk, separators, and wedges. Mirrors. — Plane and concave mirrors are both necessary in a critical examination of the tissues and organs of the oral cavity. The plane mir- ror gives the best and sharpest image, and is therefore the most important means of obtaining a view of the ^^^- 2^^- defects upon those surfaces of the teeth which are not in a di- rect line of vision. The concave mirror gives an enlarged but less distinct image ; its greatest value lies in its power of concentrating the rays of light and illuminating the obscure por- tions of the mouth. These in- struments should always be in the very best condition. A dull or scratched mirror cannot give a clear and distinct image ; such in- struments should therefore be discarded if the operator desires to perform perfect operations. The most satisfactory mirrors are those backed by a deposit of pure silver ; they cost a little more than those '^ silvered" with tin and mercury, but the added cost is more than repaid by the brilliancy of the surface and their greater durability. Working by the Reflected Image. — Defects in the teeth so often occur in positions that are entirely out of the range of direct vision that it becomes necessary in order to bring such defects into view to employ the reflecting surface of the mirror. Many operations have to be performed upon the teeth in which the only view of the fleld of operation is obtained from the reflected image in the mouth-mirror. The novice will at first find such operations exceedingly difficult from the fact that the image is reversed, and that each movement must be made in a direction opposite to that which appears to be correct. Continued practice, however, eventually overcomes these diificulties, and the operator is able to pass from a direct movement to a reverse one with apparently no effort of the will. It requires years of x^ractice, however, and a high order of skill to make perfect operations under such circumstances. Magnifying Lenses. — These instruments are of very great value in detecting minute defects in the structure of the enamel, for observing the condition of fillings previously made, or the progress of an operation, and in the examination of the finished filling. no OPERATIVE DENTISTRY. The most usefiil lenses are those which give a magnifying power of about four diameters. They may be either the watchmaker's glass (Figs. 262 and 263), held in position before the eye by the muscles surrounding the orbit, or the lens mounted with a long handle, as shown in Fig. 264. Fig. 2()3. Pointed eye-glass. Eye-glass. Such aids to the critical examination of the teeth are indispensable to the careful operator. The magnifying lens may be employed in two ways, either to directly magnify the parts which are in the direct line of vision, or by magnifying the image obtained of obscure parts by reflection upon the surface of the plane mirror. The enlarged image obtained in this manner is more sharply defined than that obtained by the concave mirror. The clouding of the Magnifying lens. mirrors and lenses may be obviated by coating the surfaces with pure glycerol. Explorers. — These instruments are absolutely necessary for the detec- tion of surface defects in the enamel and at the margins of fillings. They are "essentially prolongations of the fingers, and convey imiDressions by their vibrations to the tactile nerves." (Jack.) They are principally used to search out defects in the sulci, fissures and grooves formed by the union of the developmental lobes of the enamel, and to explore those surfaces which cannot be brought into view either by direct or reflected light. EXAMINATION OF THE TEETH AND MOUTH. Ill Several differeut forms are necessary to reach all parts of the crown of the tooth, some straight, others of various curves or angles. Fig. 265 represents some of the common forms. These may be made by the prac- titioner himself, or he can obtain them from the supply houses. No. 18 (American gauge) piano wire is the most suitable material from which to construct the points. The temper of this steel wire permits it to Fig. 265. Explorers. Fig. 2m. be bent into any desired shape necessary for this purpose, and is not so hard but that it can be filed to any degree of fineness compatible with the required strength and rigidity of such an instrument. These points may be mounted in wood or metal handles, to suit the taste and ideas of the operator. Electric Mouth-Lamp. — The electric mouth-lamp, or stomatoscope (Fig. 266), is a great aid in the detection of defects upon the proximal surfaces of the teeth. The lamj) should be placed within the mouth, at the lin- gual surfaces of the teeth, and the cur- rent switched on. The light passing through the teeth renders them in a measure translucent, and defects ux^on their surfaces or fillings appear as dark shadows. Transillumination is also a valuable means of detecting the non-vitality of the pulp. Devitalized teeth do not transmit the light as readily as those having vital pulps. This is quite easily demonstrated with the electric stomatoscope, even in obscure cases. In detecting diseases of the antrum it is indispensable. Electric mouth-lamp (reduced). 112 OPERATIVE DENTISTRY. To obtain the best results by transillumination a dark room is necessary, especially for examinations of tbe antrum. Fluid or solid material (tumors of various structure) witliin the antrum obstruct the transmission of light and produce an opacity which can be detected by comparison with the normal opposite side and with the surrounding tissues. Floss-Silk. — Floss-silk which has been just sufficiently waxed to bind the fibres together is a very valuable adjunct to the explorer in the detec- tion of proximal surface defects of the enamel and in determining the condition of fillings. In a normally arranged denture, and in a crowded condition of the teeth, the finest explorers will not reach the approxi- mating surfaces ; the floss-silk then becomes indispensable as an added means of detecting superficial lesions of the enamel, which is indicated by the character of the friction produced by moving it back and forth upon these surfaces, or by the fraying of its fibres. Very slight defects, how- ever, will sometimes remain undetected ; consequently implicit reliance must not be placed upon its negative evidence, and other means, when doubt exists, must be used to establish the conditions of these surfaces beyond j)erad venture. Fig. 267. Parr's universal separator. Separators and "Wedges. — Separation of the teeth for the purposes of examination or in preparation for filling may be accomplished in several ways. Immediate separation may be obtained by the use of the Parr, Perry, or other screw or wedge separators (Figs. 267, 268), or by driving a wooden wedge between the teeth, or it may be accomplished more slowly by the use of waxed linen tape or india-rubber strips forced between them. THE EXAMINATION. A critical examination of the oral cavity should usually be preceded by a thorough cleansing and i^olishing of the teeth, as few mouths are so scrupulously clean that this procedure will not make the after-examination more sure and thorough. Certain parts of the teeth are more liable to be attacked by caries than others ; these are in locations which give ready lodgement and retention to EXAMINATION OF THE TEETH AND MOUTH. 113 food Mhris and sedimentary deposits, and in wliicli fluids are retained or suspended by capillary attraction, — viz., the proximal surfaces^ the sulci and fissures, and the labial and buccal surfaces; the relative liability to caries being in the order named. In conducting an examination of the mouth it is best to proceed in an orderly manner, that no part may be overlooked, and that every part should receive due attention. First. Notice the appearance of the patient as to the state of health. Secondly. A general view should be taken of the whole oral cavity, in- cluding the gums, the mucous membrane of the cheeks, lips, palate, and fauces ; the tongue and the character of the oral secretions, and any devia- tion from the normal carefully noted, as these all have a more or less direct bearing upon the hygienic condition of the teeth. They are also indicative of various constitutional states and tendencies that influence the course and character of the dental diseases, the consideration of which Fig. 268. Perry's two-bar separators. should enter largely into the question which must always be decided, as to whether the best interests of the patient will be conserved by the intro- duction of temporary or permanent fillings. Thirdly. Beginning at the median line of each denture, a critical inspec- tion of every portion of each tooth should be instituted by the aid of the various appliances just described, and each defect carefully noted. Par- ticular attention should be given to those locations in which caries is most liable to be developed. The condition of all previous operations should be ascertained, and if imperfections exist they should be recorded, as should also the presence of salivary calculus, exposed pulps, devitalized teeth, pyorrhoea alveolaris, dento- alveolar abscess, the location of super- numerary teeth, irregularities, and teeth which have been lost. For the purpose of preserving the results of these examinations various forms of charts have been devised, with special signs adapted to simplify the work of making the record, any one of which will adequately serve the purpose. The operator can, however, use any of the diagrams which are found in the dental registers, inventing or adopting such signs 114 OPEEATIVE DENTISTRY. as seem best to him as a means of makiDg a rapid, expressive, and reliable record. These temporary records should be preserved until the required opera- tions and treatment have been completed, and the record of each trans- ferred to the permanent register. The careful registration of all operations of whatever character cannot be too strongly urged upon the student and young practitioner, for as time goes on they become invaluable as a means of reference. No one can remember the exact condition of each and every denture upon which he has been called to operate in the past , nor the circumstances or diflaculties which surrounded the performance of a certain operation, the condition of the pulp, or of the root-canals, etc., but many times such information would be of incalculable benefit to the patient and operator in the future treatment of the case. CHAPTEE VII. DENTAL CAEIES. Definition. — Caries (Latin, caries, rotten). Synonymes. — Caries dentes ; Caries dentium ; Dental decay ; Dental gangrene. Dental caries may be defined, pathologically as a progressive molecu- lar disintegration of the structural elements of the tooth, beginning with the solution of the inorganic substances by the action of lactic acid formed within the mouth by fermentation, and terminating with the dissolution of the organic matrix through the solvent action of the saprophytic micro- organisms. Magitot defined dental caries from its clinical aspects as " a progressive softening and continuous destruction of the hard structures of the teeth, advancing constantly from the exterior to the interior, and causing a gradual disappearance of a more or less extensive portion, or even the whole of the organ." Introduction. — Dental caries is, without doubt, the most common of all the diseases to which the human body is heir, and from which very few persons among civilized nations entirely escape. It seems to be pre-emi- nently a disease of higher civilization, as it is most common among those nations which are recognized as having the highest civilization, and yet no race or tribe of men yet discovered, whether savage, barbarous, semi- civilized or civilized, ancient or modern, have ever wholly escaped it. Archaeology, history, and anthropology all prove the correctness of the statement. Evidences are not lacking that the prehistoric man suffered from dental caries, alveolar abscesses, and other dental diseases. Many of the Egyx^tian mummies found in our great museums show well-marked evidences of caries and other diseases of the teeth. Herodotus tells us that the Egyptians had doctors for the eyes, doctors for the ears, and doctors for the teeth, etc., showing that they had need of specialists in these directions. Lancets and forceps for the extraction of teeth are to be found in museum collections of Egyptian antiquities. Artificial teeth have been found in the mouths of mummies, and state- ments have been made, though not very well authenticated, that gold fillings had likewise been discovered in the teeth. They evidently pos- sessed some knowledge of dental therapeutics, for they applied the juice of the poppy, pepper, spices, etc., to relieve the pain of toothache, and in the later stages of this disease and in the early stage of alveolar abscess ap- plied the actual cautery and counter-irritation. One mummy in the British Museum, dating back to a period about 2800 e.g., or more than 115 116 OPEEATIVE DENTISTRY. four thousand five hundred years, shows undisputed evidence of dental caries and other dental lesions. That dental caries and the lesions which result therefrom were com- mon among the Greeks in the earlier and later periods of their history- there is abundant proof. The early Greek physician gave considerable attention to the diseases of the teeth. During the latter part of the Greek eiDoch the fop or dude gave great attention to the care of his teeth, and was very proud of having them look fine and white. His more stalwart brethren ignored such attention to their personal appearance, con- sidering it effeminate and only suited to women and fools. Their physi- cians treated odontalgia after the manner of the Egyptians. Cicero credits the third ^sculapius with inventing an instrument for extracting the teeth. Diodes opposed extraction and treated toothache by medica- tion, Strabo mentions formulae for the relief of odontalgia and cosmetics for the care of the teeth. Dr. Schliemann, the great Greek archaeologist, has reported that in his excavations at the site of ancient Troy several of the crania found there exhibited teeth with carious cavities, some of which had been filled with metals, lead particularly. Coming next to the old Eoman civilization, the historical proof is abundant that dental caries and other dental diseases must have been com- mon among them, and that they practised the art of filling carious teeth and of inserting artificial teeth carved from bone and ivory. Celsus gives formulae for the treatment of toothache resulting from caries. These were compounded from resinous and aromatic substances combined with the juice of the poppy, saffron, sulphur, etc., and were to be applied to the carious cavity in the painful tooth. He also advised the use of blisters and poultices for the cure of alveolar abscess, and in- sisted upon general medication in conjunction with the local treatment. Celsus has been given the credit of inventing the art of filling teeth with gold and other substances 150 to 180 a.d. Archaeologic proof of the fact, however, that the art of filling teeth was practised by the ancient Eomans is entirely lacking. Whether this is due to the quite general custom of burning the dead, and thus destroying the evidence, or that it had no real foundation in fact, is a question that may never be settled. RESULTS OF THE EXAMINATION OF ANCIENT CRANIA. Mummery has examined and tabulated a very large number of ancient crania in relation to the prevalence of dental caries with the following results : Ancient Britons of dolichocephalic type, 2. 94 per cent. ; of brachy- cephalic type, 21.87 per cent. ; Eomano -Britons, 28.67 per cent. ; Anglo- Saxons, 15.78 i)er cent. ; ancient Egyptians, 41.66 jier cent. It will thus be seen that the i^revalence of caries bears a very close relationship to the degree of civilization and the luxurious habits indulged in by these ancient nations. Professor Broca examined a large number of crania of the ancient peoj)les of Europe, and discovered that caries of the teeth was much less frequent than at the present time, and that they were also very much worn down from attrition. DENTAL CARIES. 117 Dr. Patrick instituted an examination of all the preliistoric crania to be found in the various important museums in America, composing Pea- body Museum of Harvard University, the Army Medical Museum, Wash- ington, D. C, the collection of Dr. Samuel G. Morton in the Academy of Naturai Sciences, Philadelphia, the collection in the Davenport Academy of Science, Iowa, the collection in the Museum of the Chicago Medical College, Illinois, and a collection obtained from an ancient burial mound near the great Cohokia Temple Mound in St. Clair County, Illinois, now in the Museum of the Missouri Historical Society at St. Louis. These examinations cover a wide range of subjects, including every evidence of the diseases and anomalies of the teeth and jaws, and form a wonderful mine of information, the importance of which can hardly be over-estimated, "for there is not a question that may arise in morphology, histology, or physiology on which the facts revealed in this investigation will not shed some light. " (Patrick.) The crania examined included South Americans, Central Americans, North Americans, Europeans, Pacific and Sandwich Islanders, Egyptians, and Asiatics. Dental caries was found to be prevalent in all, but in a varying percentage, which seemingly is governed by the habits of life and the state of civilization. The South Americans included Peruvians, Chilians, Tierra del Fuegians, and Guanches. In this group 6719 teeth were examined ; 2462 were dis- eased, or 36.75 per cent. Number of carious teeth, 390, or 5.804 per cent. The Central Americans were composed of Mexicans, Guatemalans, and Nicaraguans. The teeth examined numbered 930, and of this number 250 were diseased, or 26.8 per cent. Caries was present in 44, or 4.872 per cent. The North Americans included Esquimaux, Alaskans, and various tribes from nearly every section of the United States. In this very large group 27,362 teeth were examined : 3811 showed evidences of disease, or 21.4 per cent. Of this number, 1394 were carious, or 5.093 per cent. The Europeans included Germans, French, English, Swedes, Irish, Greeks, Italians, Anglo-Americans, and a few modern soldiers. The num- ber of teeth examined was 3422. Of this number, 1373 were found to be diseased, or 40.4 per cent. The number of carious teeth was 242, or 7.079 per cent. The Pacific Islanders included Sandwich Islanders, Australians, New Zealanders, and Tchoolabees. In this group 2738 teeth were examined, and 417 were found diseased, or 15.25 per cent. ; 118 showed caries, or 4.309 per cent. The Egyptians included Africans. The number of teeth examined was 3306 ; of these, 689 were found diseased, or 20.8 per cent. Of this number, 113 were carious, or 3.418 per cent. The Asiatics included Malays, Chinese, Japanese, Armenians, Hindoos, and Burmese. In this group 2180 teeth were examined, and 336 showed evidences of disease, or 15.4 per cent. Number of carious teeth, 45, or 2.064 per cent. Miller maintains that in the meat- eating races caries is far less preva- 118 OPERATIVE DENTISTRY. lent than in tliose wbicli subsist largely upon mixed foods, and presents as evidence the fact that the dolichocephalic ancient Britons, who subsisted in all probability almost exclusively upon a meat diet, x)resented in the crania examined only about three per cent, of dental caries, while in the brachy cephalic ancient Briton, Eomano-Briton, Anglo-Saxon, and Egyptian, all of whom subsisted upon a mixed diet, the percentage of caries ranged from fifteen to forty-one per cent. Among the modern aboriginal flesh-eat- ing races he cites the Esquimaux, K"orth American (coast) Indians, North American (interior) Indians, South Americans, Feejee Islanders, ISTew Zea- lauders, and Lapps. These have all a low percentage of dental caries. The Esquimaux, who live almost exclusively upon meat and fish, have but 2.46 per cent, of caries, while the E"orth American (interior) Indians, whose diet is mostly meat, but using some vegetables, have an average of 9.09 per cent, this being the highest percentage in this group of aboriginal meat-eating races. Magitot could find in the anthropologic series of the museums of Paris no examjples of dental caries among the crania of the Mexicans, Pe- ruvians, or Patagonians, none among the aborigines of Australia, Mada- gascar, Xew Caledonia, etc., nor among the Malay and Javanese crania of Professor Wrolik. He also states that the African and Arab races are remarkable for the soundness of their teeth, the Caucasian race being the opposite of this, while the Mongolian race seems to hold a middle po- sition. The Icelanders, according to recent investigations, seem to be nearly exempt from the disease. The investigations of Barrett, conducted for the same purpose, also lead to the same conclusions. Prevalence. — Statistics upon the prevalence of dental caries among the nations of the present civilization are by no means numerous, and nearly all of thos^ which have been taken deal more with the question of the frequency of caries in individual teeth and groups of teeth than with the subject of the percentage of people who are sufferers from the disease. That the percentage is very large and apparently upon the increase there is not the shadow of a doubt in the minds of those best qualified to judge, and yet without statistics carefully prepared from many sources, at stated periods and under varying conditions of life, any statement that might be made must be taken as one of personal opinion only. It is generally conceded, however, that females are distinctly more liable to dental caries than are males. Magitot expressed the relative frequency of caries in the female by the ratio of three to two as compared with the male. Harris places the ratio much higher, claiming that it occurs in the female three times as often as it does in the male. Married women are considerably more liable to the disease than the unmarried, as the period of pregnancy and lactation are especially favorable to the development and progress of the disease. In reference to the relative frequency of caries among the men of France who were subject to military duty, Magitot introduces the statistics of the war office. These statistics deal only with young men of twenty years of age, but they may be fairly considered as showing the regular DENTAL CARIES. 119 percentage of badly defective dentures for the whole mass of the adult male population. The French law gave exemption from military service, first, when there was loss or caries of the incisors or canines of one of the jaws, and secondly, when there was loss or caries or a bad condition of the majority or of a large number of the other teeth. The exemptions from military service from 1837 to 1849, inclusive, — thirteen years, — by reason of imperfect dentures, was 25,918 out of 3,295,202, which is equivalent to an annual average of 785 in every 100,000 examined. The annual maximum was 895 in 1837 ; the minimum, 643 in 1847, or an average percentage of 7.85. If there be added to this the increased percentage of caries in females, using "Magitot's figures of a ratio of three to two, and taking an equal number of males and females, the percentage for the entire population would be 9.15. This, however, does not fairly represent the average percentage of persons affl.icted with caries ; in fact, it falls far short of the actual condition, as all of those who were received were not free from dental defects, but simply were not suffi- ciently defective under the law to give exemption. Statistics which more clearly represent the true condition of the preva- lence of dental caries among civilized nations is to be found in the report of the School Committee of the British Dental Association (Tomes), fol- lowing the examination of the mouths of 3368 boys and girls at the Han- well and Sutton schools, and at the Exmouth training shi]3. Out of this number only twenty-three per cent, had sound dentures, or, in other words, seventy-seven per cent, were afflicted with caries. The number of perma- nent teeth found to be carious was 4543, while about an equal number of temporary teeth were found in the same condition. These boys and girls ranged from three and a half to seventeen years of age, but the majority were from five to fourteen. The number of boys upon the Exmouth training ship was 480, largely recruited from these schools, the average age being fourteen years ; twenty- four per cent, had perfect dentures, or, seventy-six per cent, had carious teeth ; 44.9 per cent, had from one to four carious permanent teeth, 22.9 per cent, had from five to eight, and 5.25 per cent, had more than eight carious permanent teeth. At the Hanwell schools, out of 903 children examined at the age of eight years, 83 furnished 127 carious permanent teeth, all first molars ; at the age of twelve years 90 children had 244 carious permanent teeth ; the percentage of unsound permanent teeth in this number of children at the age of six is 53, at the age of twelve, 271, and at the age of fourteen, 300. The Association Committee made an attempt to compare the condition of the teeth of the children in the poor^ and high-class schools, but the numbers in the latter were not sufficiently numerous to give conclusive results, as only 205 children of this class were examined, and these did not compare favorably with those less fortunately placed. Another interesting fact in reference to the prevalence of caries is the wide difference existing in the relative frequency of the disease in the upper and the lower jaw, and between individual classes and groups of teeth. 120 OPERATIVE DENTISTRY. The diflferences between the right and left sides are so small as to be of no jpai'ticular moment ; hence in the following tables this difference will only be noted in the footings. Ottofy computed from an examination of 14,644 teeth of American public-school children that caries was i^resent in 27.33 per cent, in males and 32.67 per cent, in females. The teeth examined comprised 5100 deciduous and 9544 permanent teeth. Of the 5100 deciduous teeth examined the following percentage were found carious : Lower central incisors 0.03 Lower lateral incisors 0.09 Upper central incisors 1.32 Upper lateral incisors 1.42 Lower cuspids 1.99 Upper cuspids 2. 78 Lower first molars 6.52 Upper first molars. . . 6. 72 Lower second molars 7.80 Upper second molars 9. 77 Of the 9544 permanent teeth examined the following percentage were found carious : Lower cuspids 0.01 Lower lateral incisors 0.04 Lower central incisors 0.05 Upper cuspids. . . 0.05 Lower first bicuspids 0. 10 Upper second bicuspids 0.28 Lower second bicuspids 0.30 Upper first bicuspids 0.38 Upper lateral incisors 0.55 Upper central incisors 0.85 Upper second molars , 1.25 Lower second molars 1.57 Upper first molars 7.20 Lower first molars 7.70 This table gives a better showing for the American public- school children than that furnished by the committee of the British Dental Asso- ciation of the condition of the teeth of the children found in the Hanwell and Sutton schools. This difference is explained by the fact that the children in the Hanwell and Sutton schools were from the poorest class of English society, while the American public schools are patronized by all classes of society. The Schleswig-Holstein Dental Association, in a recent investigation * into the prevalence of dental caries among school- children in Northern Germany, conducted by Dr. Greve, of Lubeck, presents an extended report upon the subject, of which the following table is a summary : * Cor. Blatt. fiir Zahn, July, 1899. DENTAL CARIES. 121 Age. Six to eight years Nine to ten j'ears Ten to twelve years. . . Twelve to fifteen years Number Examined. Perfect Teeth. Carious Number. Per cent Number. 6060 407 6.8 5653 4990 268 3.4 4732 3518 149 4.3 3369 5157 172 5.5 4985 Per cent. 93.2 96.5 95.7 94.5 Of the 19,725 children examined, ninety-five per cent, showed dental caries. It was also noted that there were 372 anomalies of various characters, including harelip, cleft palate, irregularities, Y-shaped jaws, and, singu- lar as it may seem, only one case of congenital syphilis was found. The investigation covered the children of nineteen towns. The boys were found to have somewhat better teeth than the girls, the difference being about three per cent, in favor of the boys. Magitot places the relative frequency of caries in the uj)per and lower jaw respectively in the proportion of three to two. This author presented the following analysis of ten thousand cases, from which the above conclusion is drawn : Central incisors Lateral incisors. Canines 642 1 777 1 515 First bicuspids 1,310 < Second bicuspids 1,310 < First molars 3,350 1,736 1 Second molars. Third molars 360 612 upper. 30 lower. 747 upper. 30 lower. 445 upper. 70 lower. 940 upper. 370 lower. 810 upper. 500 lower. 1,540 upper. 1,810 lower. 690 upper. 1,046 lower. 220 upper. 140 lower. Total 10,000 10,000 Upper 6,004-. Right side '^'''^^li Lower 3,996 / ^^'^^^ Left side 5,209 / ^^' 000 Hitchcock, in Wedl's ^^ Pathology of the Teeth," presents the follow- ing table of twenty thousand cases prepared from records of fillings and extractions in which the ratio of frequency of caries in the upper teeth is placed at 1.9 to 1 in the lower, or nearly two to one : Central incisors.. 2,189{ 2,101 upper. <- 88 lower. Lateral incisors 1,954 < ' ^„ , I 127 lower. Canines 1,261 1 ^'^^^ ."PP"^" t- 203 lower. First bicuspids 2,073| 1.588 upper. t. 4So lower. 122 OPEEATIVE DENTISTRY. Second bicuspids 2,585 1 First molars 4,399 Second molars 3,615 | Third molars 1,924 1 1,715 upper. 870 lower. 2,273 upper. 2,126 lower. 1,675 upper. 1,940 lower. 899 upper. 1,025 lower Total 20,000 20,000 Upper 13,136 \ go OOO ^'^^* ^'^^ ^'^'^^^ \ 20,000 Lower 6,864 i ' Leftside 9,849 J Tomes presents a table of 2638 cases of extractions on account of caries or its consequences, as follows : Central incisors 25 Lateral incisors 62 Canines 36 First bicuspids • 227 Second bicuspids 393 First molars 1090 Second molars 575 Third molars 230 Total 2638 A table prepared by Pare and Wallis from tbe records of 30,012 cases of extractions at Guy's Hospital gives the following results in percentage : First molars 10,891, or 36.30 per cent. Second molars 5,904, or 19.68 per cent. Second bicuspids 4,179, or 13.93 per cent. First bicuspids 3,212, or 10.70 per cent. Third molars 2,639, or 8.76 per cent. Lateral incisors 1)202, or 4.00 per cent. Canines 1,098, or 3.66 per cent. Central incisors 884, or 2.94 per cent. Separating the upper from the lower teeth in this table of cases. Pare and Wallis have given us the following percentage for the individual teeth : Lower first molars 5632, or 18.7 per cent. Upper first molars 5259, or 17.4 per cent. Lower second molars 3489, or 11.62 per cent. Upper second bicuspids 2503, or 8.33 per cent. Upper second molars 2415, or 8.04 per cent. LTpper first bicuspids 2288, or 7.623 per cent. Lower second bicuspids 1676, or 5.58 per cent. Lower third molars 1322, or 4.4 per cent. Upper third molars 1317, or 4.38 per cent. Upper lateral incisors 1013, or 3.37 per cent. Lower first bicuspids 924, or 3.07 per cent. Upper canines 861, or 2.86 per cent. Upper central incisors 754, or 2.51 per cent. Lower canines 237, or 0. 78 per cent. Lower lateral incisors 189, or 0.62 per cent. Lower central incisors 133, or 0.443 per cent. DEXTAL CARIES. 123 In these tables it will be noticed that the first permanent molars are most susceptible to those influences which produce decay, and that the lower molars are slightly more susceptible (18.7 per cent.) than the upper (17.4 per cent.), the difference being 1.3 per cent. The second lower mo- lars stand next in susceptibility ; these are followed by the upper second bicuspids and the upper second molars, and so on down the list until the lower canines, laterals, and centrals are reached, in which the percentage of decay is so small as to almost constitute immunity. The agency which gives this i)rotection or immunity is thought by some authorities to be the secretion of the submaxillary glands, by others the presence of fluid in the floor of the mouth, which is kept in constant motion by the movements of the tongue, and thus retarding the jjrocess of fermentation ; but whatever it is, the protective effect is not efficacious in the posterior part of the mouth, and it will be noticed that the agency grows less and less efficacious from the incisors backward. From the foregoing pages it will be readily seen that all of the inves- tigations in reference to the i^revalence of dental caries among ancient and modern races conclusively proves that the disease has always been present, at least as far back as evidence can be obtained from written his- tory and archseologic research ; that it was comparatively rare among abo- riginal tribes and nations who per force lived a simple life ; while among those ancient and modern races and nations who had attained to a high state of civilization, with its attendant luxuries and enervating habits, it has been very common, while at the present time, as proved by the statis- tics recently gathered, it is increasing in a most alarming manner. ETIOLOGY. The causes which are responsible for the universal prevalence of this disease are many and varied. These are divided into two general groups, — viz. : Indirect or predisposing, and direct or exciting causes. The former deals with certain conditions which have been established beforehand, through inheritance of constitutional tendencies or special dyscrasia and local de- velopmental defects or anomalies ; while the latter treats of those phe- nomena which are the active agents in establishing and maintaining the progress of the disease- Predisposing Causes. — The conditions which are here enumerated as predisposing causes of dental caries may be divided into two groujDS, — viz., constitutional and local. The constitutional predisposing causes are : Environment. Climatic influences. Miscegenation. Excessive mental strain in growing children. Hereditary influence. Influence of inherited disease. Exanthematous disease. Continued fevers. 124 OPERATIVE DENTISTEY. The local predisposing causes are : Structural defects of the teeth. Traumatic injuries. Irregularities in the arrangement of the teeth. Abnormal oral secretions. These causes are all more or less important factors in the predisposition and susceptibility of the teeth to caries, by reason of their influence upon nutrition and vital resistance, or of their local surroundings or environment. Upon a ]3roper appreciation of the depressing influences of these con- stitutional conditions upon the function of nutrition and of vital resistance to disease, and the effort to correct or prevent these evil influences in the future, will depend in no small degree the perfection in structural development and the integrity of the teeth of the generations yet unborn. CONSTITUTIONAL PREDISPOSING CAUSES, Environment. — The term environment as here used is intended to include all those conditions of life which are the results of civilization, — viz., the xDhysical; mental, and social conditions, and the food habit. It has already been stated that dental caries is most prevalent among those races and nations which have attained to the highest degree of civili- zation, and there can be no doubt that a deterioration of the teeth is a con- stant accompaniment of the progress of civilization. Why civilization should produce such effects is not a very difficult question to answer. The civilization of a race or a nation is a gradual process, and one which affects both the intellectual and physical development. The evolution of a savage or barbarous race to the plane of a civilized people is the work of centuries. The whole trend of thought and of moral obligation and responsibility to others has to undergo a radical change. With these changes come higher aspirations, an enlargement of intellectuality, and a desire for more knowledge. Knowledge is only attained by study and intellectual pur- suits, which of necessity greatly change the habits and mode of life. A savage, nomadic jDCople, constantly warring with their neighbors, begin the process of evolution by forming confederations against a greater enemy ; they next intermarry, and later, because their common interests demand it, settle in communities and establish permanent homes. As their intellectuality increases, the older and wiser ones teach the younger the value of greater knowledge than they themselves have possessed, as this would give them an advantage over their enemies. Finally some one of their number arises whom they look upon as having more wisdom than the rest, and he becomes a leader, and perhaps a teacher of the tribe. Their language is developed, and characters are invented by which to express the language in writing. Later, schools are formed, in which the more ambitious are taught in the knowledge possessed by the wise men. As a result, larger communities are formed, industries spring up, cities are builded, the confederated tribes become a nation, and a ruler is chosen. Contact with other nations broadens the intellectual horizon and increases the ambition of the people to be equal to their neighbors. These ambi- tions stimulate a desire for wealth, and riches result in the introduction DENTAL CARIES, 125 of new and more luxurious habits of life and greater devotion to intellec- tual attainments and pursuits, as well as the cax^acity to enjoy them. The nation has now reached the plane of civilization. With this evolu- tion has come higher mental and nervous endowments and greater capacity to enjoy and to suffer ; but this mental and nervous development has been very largely evolved at the expense of the physical system. The powers of physical endurance and of resistance to disease have been greatly lowered by the change in environment. War and the chase have given place to the counting-house and the shop ; the tent and the "dug-out" are now represented by the cottage and the mansion ; the simple diet of meat and a few vegetables, often uncooked, has been replaced by an endless variety of foods, containing large quantities of fermentable substances, and so i3repared by the culinary art that the teeth and jaws get very little of the exercise which is so necessary to maintain them in a healthful con- dition ; while the use of food containing large quantities of such ferment- able substances as starch and sugar present the necessary elements from which the acids are formed which act upon the teeth, thus inducing dental caries and many other diseases as sequelae. Those nations of the present day which suffer most from dental caries are the Anglo-Saxons of America and Great Britain and the great European nations. The growth of modern dental science and the per- fection of the art among these peoples has been a work of necessity, and one which from its surgical aspects has kept pace in its development with the demands which have been laid upon it. But viewed from the more important aspect of prophylaxis, it has not yet attained nor kept pace with the ever-increasing needs in this direction. When one stops to consider how wide-spread and universal dental caries has become, and the increasing number of teeth that are destroyed by the disease every year, we are appalled by the problem, and wonder if the human race is not destined to become endentulous. The teeth of the present generation seem to be inferior to those of their immediate ancestors, while the children of to-day have, as a rule, a greater predisposition to dental caries than their parents. In other words, there seems to be a gradual deterioration in the structural development — per- fection of development — of the teeth, and a lowering of the resistive powers or the vital energy of the system against the encroachment of disease. Perfection in the structural development of the teeth of city-bred chil- dren of the middle and better classes of society is the exception, defective teeth the rule. Little children between the ago of three and six- years are frequent sufferers from dental caries, odontalgia, and alveolar abscess, while very many have defective first molars which require attention as soon as they are erupted. This is the age of steam and electricity, of the lightning exj)ress train and the ocean greyhound, of the electric telegraph and the telephone. Men, and women too, have seemingly partaken of the energy and speed of these forces. It is an age of rush and of whirl. Men and women vie with each other and with their sex for place and power. In business and 126 OPERATIVE DENTISTRY. social life, in educational matters, in their pleasures and vices, they go at high-pressure speed, and as a result often break down at a period of life when under more favorable circumstances they would still be in their prime. These conditions are manifest everywhere in the civilized world, but are most noticeable in the great cities, where the intensity of the struggle of the poor for existence and of the well-to-do and the rich for supremacy over their fellows in business, social pleasures, education, and display are the greatest. Children born under such circumstances have generally constitutions which are far from equal to those inherited by their parents, and as a consequence they are handicapped in their struggle for existence either by the direct inheritance of disease, or of tendencies and predispositions to disease which are the result many times of the terrible deprivations of poverty, or of overwork or over-indulgence in the luxuries and the pleasures of life, or of the indiscretions or the vices of their parents or earlier progenitors. Such an environment can only result in enervation, depression of vital forces, malnutrition, and defects in the mental, the nervous, and the physical development. Climatic Influences. — The influences of climate as a predisposing cause of caries in these days of immigration, colonization, and inter- national trade has come to be an important factor, and it should receive that recognition from the scientific men of the profession which its impor- tance deserves. It has often been remarked, especially in India and other tropical climates, that the white man was physically often very profoundly affected by the radical changes in the climate and environments. This is particularly noticed in the increased susceptibility to disease and in a lowered vitality or resistive power, so that it has become a recognized fact that these people must, as a rule, return to their own country every seven to ten years in order to recuperate their lowered vitality and physical stamina. The depressing effects of the climate are so severe to some indi- viduals that a residence of one or two years under its influences is sufficient to completely break their health. It can therefore be readily understood how such depressing and ener- vating influences acting upon the general system may lead to malnutrition, loss of nervous energy, vitiation of the secretions, particularly of the oral cavity and the alimentary tract, and thus act as predisposing causes of dental caries. That the teeth of the average Briton who takes up his residence in India for a period of years decay more rapidly than they did when at home seems to be the general opinion among them. The same opinion prevails among the American missionaries who have spent a number of years in India and other tropical climates. These opinions have been substantiated by the experiences of the British troops in South Africa and the United States troops in Cuba and the Philippines. It is a notable fact that in this country, which receives every year large additions to its population from foreign nations, principally from Eu- rope, these people, after a few years of residence, often suffer greatly from the ravages of dental caries. This the writer has observed to be the case DENTAL CARIES. 127 more particularly among the Irish and Scandinavians. This tendency has been ascribed to various causes ; some authorities have maintained that it was due as much to a change in the food and social surroundings as to climatic influences. Wedl^ in writing upon this point, says, ''If it be true that geologic and climatic conditions, and the means of subsistence which are connected with the same, have such a preponderating influence in respect to the fre- quency of caries, then it is impossible to explain the fact that foreigners belonging to different races, who are exposed to the same conditions as the native inhabitants, still retain the typical structure of their teeth, as well as that of their bodies, and continue to furnish the proportion of dental caries peculiar to their race. This is found to be the case with the isolated Slavonic races of Austria and the descendants of the Celtic race in France." To this remark Hitchcock appends the following: "As geologic, cli- matic, and social conditions exercise a predominant influence upon the growth and development of the various races, mentally as well as physi- cally, it is evident that the development of the dental organs cannot fail to be controlled by the same causes. In this country, which is annually receiving large numbers of foreigners by immigration, the typical traces of race are usually effaced after the lapse of a generation or two, the de- scendants possessing all the peculiarities, and their teeth apparently being as liable to caries as the teeth of Americans generally." The personal observation of the writer leads him to the opinion that the children of immigrants born in this country are not, as a rule, as robust as their parents, and that they suffer more from dental diseases. Miscegenation. — The intermarriage of individuals representing dis- tinct nations and races has come to be a very common occurrence all over the civilized world. The railway trains, the steamships, the telegrai^h, and the submarine cable have broken down the barriers that once existed be- tween nations, and have stimulated the individual to seek knowledge, wealth, and home in other climates than his own, while the enlightenment which has followed in the path of these great inventions has swept away in large measure the religious and race prejudice which befo retime had pre- vented such alliances ; as a result, the human family is entering upon a course which is destined sooner or later to bring about an amalgamation of those contiguous nations and races which belong to the higher class of civilization. The crossing of distinct races, like the Anglo-Saxon and the negro, or the Mongolian and the Malay, produces a progeny which is in no way the equal, physically, of either of the races from which they sprang. The difference is principally noticed in a lowered state of vital resistance to disease and in the powers of endurance under physical strain. Miscegenation exercises a depressing influence upon the integrity of all of the structures of the body, tooth-structures included. The crossing of races and nations is not generally productive of benefit, especially when so widely separated as are those of the human species. ' ' Human hybrids are notably deficient in physical completeness and vital power, nutrition 128 OPERATIVE DENTISTRY. is more or less impaired^ and the physiologic x)rocesses are weakened, so that the entire economy is depressed and abnormal." (Thompson.) These facts were so generally recognized in this country during the days of slavery, that the slave-dealer never made the mistake of buying mu- lattoes to fill an order for slaves to work in the rice-fields and sugar plan- tations of the far South, as these people did not possess the two great pre- requisites for this kind of labor, — viz., resistance to disease and superior powers of physical endurance. The mulattoes on this account were generally employed as house ser- vants, while the blacks were in demand as field-hands, because they pos- sessed in a much greater degree the necessary qualifications for hard labor and resistance to those diseases which are so common in the lowlands of the South. The half-breeds of the Malay Archipelago and the Eurasians of India are also examples of the degenerating physical effects of miscegenation. The effects of the amalgamation of nations is particularly seen in the American people, who are receiving a continuous stream of foreign and heterogeneous blood into their veins. ''The depression that has ensued to the physique of the people of the United States as a natural result of these intermarriages may have contributed somewhat to the existing extra defectiveness of the teeth of Americans over those of nations who have been less subject to the effects of miscegenation." (Thompson.) Excessive Mental Strain in the Growing Child. — Excessive men- tal strain coming at that period in the history of the child when the de- velopmental changes are most active and when the nervous system is in a very exalted state and responds most acutely to all forms of stimulation and depression, is often productive of conditions which lower the general tone of the system and disturb the functions of digestion, assimilation, and nutrition, and thus lay the foundation for a train of physical ailments from which the child may never fully recover, while the nerve-centres may be so impressed as to produce nervous prostration, chorea, epilepsy, paralysis, and kindred complaints. This lowering of the general tone of the system, the disturbance to the nutritive functions, and the nervous phenomena which may develop as a result of mental strain in growing children play an important part in the greater predisposition to dental caries so generally noticed at this period of life, by producing devel- opmental defects in the structures of the teeth, vitiated oral secretions, and rendering the child less able to successfully cope with disease-producing germs. The tendency of the age is to force children in their school work to the limit of what they are mentally and physically able to endure. This system ai)plied to ambitious children often operates to their disadvantage, as they are inclined to go beyond their strength, and sooner or later the health is undermined, the teeth break down from caries, and, unless the strain is removed and the child given a complete rest, change of air, and surroundings, physical and nervous prostration are the result. The author has often found it necessary to advise parents and guar- dians to remove a child from school to save the health from being wrecked. DENTAL CARIES, 129 In many of these cases the rapid decay of the teeth was the prominent symptom which attracted his attention and led to an investigation of the general health and surronndiugs of the child. Hereditary Influence. — Inherited tendencies or x^i^edisposition to caries of the teeth is often well marked in certain families. This predis- position is donbtless established by the transmission of some abnormality in the form of the teeth or by a direct structural malformation of the enamel or the dentin. The children of parents whose teeth have been lost early in life from dental caries are unquestionably very prone to be affected with like conditions. So well has this hereditary influence been estab- lished that it is not an infrequent exj)erience to find special teeth in mem- bers of the same family attacked by the disease, and at relatively the same period of life. Influence of Inherited Disease. — Hereditary tendencies and predis- positions to certain diseases like tuberculosis, rheumatism, gout, various nervous affections, and insanity are often well marked ; but syphilis is the only disease that has been positively demonstrated to be directly trans- mitted from parent to child. The syphilitic virus predisposes to dental caries through its depressing influence upon nutrition and its tendency to attack epithelial structures, thus producing atrophy of the ameloblasts in those teeth in which the process of calcification is about to begin, and forming faults or imperfec- tions in the enamel which later become the starting-point of caries. If the student will refer to the chart showing the progress of calcifica- tion of the permanent teeth (Fig. 225, page 78), he will notice that the only teeth in which calcification is progressing up to the end of the second year of existence are the first molars and the central and lateral incisors, and these are the teeth which are always the most profoundly affected by the action of the virus in inherited syphilis. This will be readily understood when it is remembered that the most active stage of the disease in these unfortunate children is during the first and second years after birth. When this stage is prolonged to the third year the cuspids are also affected. Jonathan Hutchinson first called at- tention to the peculiar effects of inherited syphilis upon the permanent teeth, and offered the only adequate explanation of their malformation, — viz., interrupted nu- trition. These malformations consist of an atrophied condition or lack of develop- ment of the enamel upon the morsal surfaces of the first molars and the morsal edge of the incisors, with a notched condition of the morsal edge of the central incisors, semilunar in outline (Fig. 269). The incisors, both upper and lower, have often a stunted appearance, and are narrower at the morsal edge than at the cervix. The upper lateral incisors are sometimes very much dwarfed, resembling pegs or inverted cones. Hutchinson re- garded the semilunar notch in the central 'incisor teeth as diagnostic of 9 Fig. 269. Syphilitic teetli. (After Hutchinson.) 130 OPERATIVE DENTISTRY. inherited syphilis. Tliis view has, however, been called in question, as the same condition has been noted in children to whom mercury had been administered in infancy until the system was profoundly impressed, but who had not inherited syphilis. And inasmuch as mercury is usually administered in inherited syphilis, the question has been raised as to whether the peculiar malformation is due to the effects of the virus or to the drug. On the other hand, the malformation is common in children with inherited syphilis who have received no treatment of any kind. It therefore seems probable that both the virus and the drug, by their de- pressing effects upon the functions of nutrition, are capable of producing these peculiar malformations. Teeth of this character are very prone to caries at those points where the enamel is defective or entirely lacking, and yet certain cases will resist the inroads of the disease for many years. Exanthematous Diseases and the Continued Fevers. — The exan- thems and the continued fevers occurring at the time of dental development retard or arrest this process for a shorter or longer period, according to the severity of the disease and the recuperative powers of the child. This interference with nutrition is indelibly impressed upon the developing teeth by pits and grooves which encircle the crowns of the teeth at that I)articular part of the enamel which was undergoing calcification at the time, or the enamel may be imperfectly developed at the morsal edge of the incisors and the cuspids, or at the cusps of the molars. Sometimes the enamel is entirely absent over a considerable portion of the crown. The teeth which are most liable to be affected in this manner are the first permanent molars, the incisors, and the cuspids. Various other diseases, like diphtheria, convulsions, and the gastric and intestinal affections, so common among children during the period of dental development, may produce like developmental defects. Cases of this character are of frequent occurrence. One of the most marked instances of this kind which ever came under the observation of the writer was a little boy ten years old, who was at this age in apparently good health, but rather small and slender for one of his years, and of strumous diathesis and nervous temperament. His teeth up to this age had erupted at the normal period. The deciduous teeth had all been well formed, but very frail, and nearly all of them had been treated for caries. The permanent teeth which had so far erupted were the sux)erior and in- ferior first molars, and the central and lateral incisors and first bicuspids. All of these teeth except the bicuspids were devoid of enamel over the whole extent of the crowns, except a narrow band at the cervical margin. The denuded surfaces were quite sensitive to the touch of instruments, or the action of acids, sweets, or thermal changes. The bicuspids were nor- mally developed. The child was born of a highly cultured but extremely nervous mother, with tubercular tendencies. For the first three years of his life the child was continually ill, suffering from gastric troubles and convulsions whenever there was any slight irritation to the nervous system. If his milk were ever so little changed by lactic acid fermentation, or he were ever so slightly overfed, convulsions usually followed, and it was DENTAL CARIES. 131 only by the most careful nursing that he was carried through the critical period of first dentition. There is also a rai)id increase in the progress of caries, as well as a greater predisposition or susceptibility to the disease in pregnancy, tuber- culosis, typhoid fever, diabetes, and other wasting diseases. Similar con- ditions jprevail in ansemic and leuksemic states. It is a noticeable fact that in young girls who are suffering from chlorosis the teeth often exhibit an increased tendency to caries and exceptionally rapid progress of the disease. Certain occupations have been thought by some authorities to predis- pose to caries ; for instance, millers, bakers, and candy-makers show an especial liability to caries, as do also workers in alkali, phosphorus, arsenic, chlorine, and sulphuric acid manufactories. LOCAL PREDISPOSING CAUSES. Structural Defects of the Teeth. — Structural defects in the enamel, the result of constitutional conditions which have impaired nutrition and thus prevented the proper development of this tissue, are a most impor- tant factor in predisposing the teeth to caries. The most observable of these defects have just been referred to, — viz., pits or honey-combed con- ditions, grooves, and the absence of enamel upon certain portions of the crowns. The less noticeable but more important defects are those which may be found in almost all teeth, even of the most perfect development, — viz., the sulci, fissures, and pits formed by the union of the developmental lobes. Fig. 270 shows such a condition. At these points the enamel-rods many times seem to have been imperfectly cemented together, or the sulci and fissures are so deep as to give ready lodgement for food debris. These conditions invite the establishment of caries by making it possible for the micro-organisms of the disease to find a lodgement where, undisturbed, they may propagate and flourish. Many of the enamel defects are so infinitesimal in size as to require the aid of high-power objectives for their discovery, and yet they are sufii- cieutly large to give lodgement to masses of micro-organisms. Structural defects of the enamel which leave the dentin exposed to the action of the micro-organisms favor rapid disintegration of this tissue ; but if the exposed surface of the dentin is of such shape or in such a loca- tion that the lodgement of bacteria can be prevented, caries will be no more likely to occur at these points than u]3on the enamel itself. The rapidity with which caries progresses in the dentin will depend in large measure upon the character of the structure of this tissue. Den- tin in which the interglobular spaces are numerous does not seem to possess the same degree of resistance to the invasion of the micro-organisms of decay as those teeth which are more perfectly organized. Black has shown very conclusively that the chemical constituents of the teeth do not exhibit a sufficient variation to account for the differences observed in the rapidity with which structural disintegration takes place in caries, and that the variations in the amount of lime-salts in the dentin are not enough to exiDlain their variation in hardness. 132 OPERATIVE DENTISTRY. It must be conceded^ however, tliat alterations in the structural organi- zation and chemical constituents of the dentin modify to a greater or less extent the progress of the disease. ^'The forces of attack being equal, a poorly organized and badly formed tooth will succumb sooner than one perfectly formed and of completely organized tissues ; this law is constant in all biology." (Burchard.) Another structural defect which predisposes to caries is the deviations from the normal in the external forms of the teeth. Teeth of the most perfect form are broader at their morsal surfaces than at the cervix ; in other words, are bell-crowned. This form of tooth in a normal dental arch permits approximal contact with each of its neighbors at one point only, — viz., near the morsal margin of the approximal surface of the bicuspids and molars and the morsal edge of the incisors and cuspids, thus separating each tooth from its fellow by V-shaped interspaces, which are generally kept clean by the passage through them of the fluids of the mouth. If, on the other hand, the labio-lingual diameter of the crowns is much greater than the mesio-distal, and the approximal surfaces are flattened, these surfaces of the teeth lie closer together, nearly if not quite obliterating the proximate interspaces, thus making it difficult or impos- sible to keep them free from alimentary debris, and favoring the lodgement and growth of the bacteria of fermentation. Traumatic Injuries. — Defects in the enamel caused by traumatic in- juries are not nearly so common as the developmental defects, and are not, as a rule, so liable to become the starting-point of caries. Injuries which fracture the enamel, leaving the dentin exposed, if occurring at points which are subject to the friction of mastication, or of such shape as to be self-cleansing, rarely develop caries ] but when the reverse is the case, caries will often be established in a very short time. Injuries which cause crushing or splitting of the enamel without dislocation of the frag- ments are much more liable to become the starting-point of caries than those fractures which cause loss of tissue, from the fact that they offer much more favorable conditions for the entrance of bacteria and their undisturbed propagation. Fig. 271 shows caries following a crack in the enamel. Irregularities in the Arrangement of the Teeth. — Teeth which are irregular in their arrangement in the arch, no matter how perfect they may be in structure and form, have a much greater predisposition to caries than those which have a normal arrangement. Nature in constructing the typical dental organs of man and arranging them in the perfect arch, placed them in the best possible condition to withstand the action of those destructive agencies which continually sur- round them. Any deviation from this perfection of form and arrange- ment must, therefore, necessarily predispose the teeth to be acted upon by these agencies, while the degree of predisposition will be largely con- trolled by the character and degree of the irregularity in form and po- sition. By mal-arrangement of the teeth certain of their surfaces are rendered very difficult or well-nigh imiDOSsible to cleanse by natural or artificial Dental fibres, penetrating the enamel Caries of n''% enamel in fissure Fig. 270.— Section of human molar, showing caries of enamel following a fissure. X 95. Dentinal tubuli ,,,,,„,, b,,,,. entering the Wf '!''»«« ■n^r.^ el I'j ifl Hi enamel Dentin iMij Fit. J71 — Caries followin Caiies follow- ing crack in enamel Enamel DENTAL CARIES. 133 means, and thus the active agencies of caries are furnished with the best possible conditions for the establishment of their destructive work. Injuries, extractions, or the necessary loss of a tooth often cause mal- position of adjoining teeth, and render the approximal surfaces more diffi- cult to be cleansed by the natural agencies of the mouth, and by that much establish a greater predisposition to caries. The injudicious use of the file is also a predisposing cause of caries, and secondary caries is often invited by failure to restore the normal contour of the teeth when inserting approximal fillings. Broad contacts upon the approximating surfaces of the teeth are grave deviations from the normal condition of a perfect dental arch, and should never be allowed to obtain as the result of opera- tion, as all such conditions invite a recurrence of the disease. Abnormal Oral Secretions. — ITormal mixed saliva is generally alka- line in its reaction. Parotid saliva is faintly alkaline, while the secretion from the submaxillary glands is more strongly alkaline, as is that from the sublingual glands. The secretion from the parotid is a clear, watery fluid, while that from the submaxillary glands, though a limpid liquid, is quite viscous, a quality which under the influences of cold gives it an almost gelatinous consistence. The secretion from the sublinguals is a limpid viscid fluid, but rich in ptyalin, which gives it a ropy consistency. The secretion from the buccal mucous glands is also a viscid fluid, rich in mucin, and has an acid reaction. Changes in the character of these secretions often take place as a result of certain morbid conditions of the mouth or of the general system. The morbid oral conditions which may induce alterations in the character of the saliva are stomatitis in its various forms, gingivitis, tonsillitis, pharyngitis, and diphtheria. These inflammatory conditions greatly augment the secretion of buccal mucus, and as a consequence there is a marked increase in the acidity of the oral fluids. This is made evident by the use of litmus paper, and ^'by the solution and consequent disappearance at such times of deposits of tartar." (Magitot.) The morbid conditions of the general system which may induce altera- tions in the character of the oral secretions are certain acute and chronic diseases. Among the general acute affections which may produce these eifects are the eruptive fevers, typhoid and malarial fevers, pneumonia, bronchitis, pleurisy, gastritis, enteritis, and the constitutional effects of such drugs as mercury, potassium iodide, etc. In all of these conditions it has been observed by various writers, from Donne (who called attention to these facts in 1835) to the present time, that the oral secretions presented an acid reaction, and that accom- panying this condition there was hypersensitiveness of the teeth, with an increased predisposition to caries. The general chronic affections in which these changes are most often noticed in the oral secretions are rheumatism, gout, dyspepsia, chronic enteritis, dysentery, gastralgia, and pulmonary tuberculosis. "Their effect is to exaggerate the production of ptyalin, the agent of viscidity, 134 OPERATIVE DENTISTRY. and to excite a hypersecretion of mucin, two phenomena caused either by the direct influence of intestinal alteration or by reflex action of the gen- eral condition upon the conditions of the mouth." (Magitot.) Like conditions are frequently observable in certain physiologic states, as in i)regnancy and lactation. Acid reaction of the saliva and hyper- sensitiveness of the teeth, with an increased predisposition to caries, is so common among women during these states that the tendency among them at these times to lose their teeth has been crystallized into the terse adage, " for every child a tooth." In mouths which show an acid reaction of the saliva it is common to find an increased quantity of ptyalin and mucin, which give an albuminous, ropy appearance to the secretion. These substances, being capable of coagulation, give a tenacious char- acter to the saliva and cause it to cling to the surfaces of the teeth, thus forming a convenient medium for the growth and destructive action of the bacteria of decay and the retention and fermentation of food debris. CHAPTEE YIIL DENTAL CARIES (CONTINUED). The agents whicli are immediately responsible for the production and maintenance of a disease are termed its direct, exciting, or active causes. These causes are often obscure, and many times entirely hidden from observation. Dental caries was thought by many of the older writers to be analo- gous to caries of bone, but this cannot be the case, for the physical phe- nomena of disintegration of these tissues are so very different. Caries of the bone is an inflammatory molecular disintegration of tissue, a retrograde metamorphosis. The organic and inorganic substances or elements are dissolved or break down together, and are carried away in the sanies or pus which is formed as a result of the inflammation. In caries of dental tissue there are no inflammatory symptoms except that of increased sensibility. Modern research has demonstrated that caries is caused by zymogenic organisms. The inorganic elements of the tissue are first removed by chemical solution produced by the acid-form- ing bacteria of the mouth, while the organic material or basis substance becomes gangrenous and is afterwards dissolved by the liquefying action of the sapro]3hytio micro-organisms and is washed away. For more than two thousand three hundred years dental caries has formed an interesting subject for medical writers and theorists. The etiology of the disease has always furnished a most interesting field for original investigation and research, while the peculiarities of the physical i)henomena presented by the disease and the obscurity of the causes which produced them have led to many and divers opinions. As a result, several theories have from time to time been advanced to explain the phenomena which are manifest in the dissolution of these tissues. The ancient physicians and dentists who made any attempt to inquire into the causes of the affection seemingly contented themselves with offer- ing hypotheses more or less ingenious, but based in part upon experience and clinical observation, to account for the physical phenomena of the disease. No real investigation, however, that could be called scientific was at all possible until the invention of the microscope opened the way for the study of the histologic structure of the dental tissues, both normal and pathologic, and the minute bacterial forms which we now know to be the cause of so many diseases. History. — It will be interesting to the student to briefly review the following theories and trace the evolutionary steps by which the direct causes of the disease were finally discovered : 135 136 OPERATIVE DENTISTRY. 1. The Humoral Theory. 2. The Vital or. Inflammatory Theory. 3. The Worm Theory. 4. The Putrefaction Theory. 5. The Chemical Theory. 6. The Electro-Chemical Theory, 7. The Germ Theory. The Humoral Theory of Caries. — Hippocrates (B.C. 456) and his pupils were humoral pathologists. Hippocrates taught that the body con- tained four fluid humors, — viz., blood, phlegm, yellow bile, and black bile ] that a proper or due proportion of each of these humors constituted health, while a disturbance of the proportions resulted in illness. He ascribed all diseases to this cause ; hence he and his followers ascribed dental caries to a bad condition of the humors, — viz., to the stagnation of depraved juices in the teeth. This view was generally maintained by physicians for more than a thousand years, and is still prevalent in the traditions of the common people. Bourdet (1757) still maintained the humoral theory of Hippocrates, while most of his contemporaries accepted the vital theory. He claimed that when the fluids contained in the vessels of the tooth are too thick they coagulate, and since they are confined, putrefy and act directly upon the structures of the tooth, producing caries. He also called attention to the fact that when a tooth decays, its fellow upon the opposite side of the jaw is sooner or later similarly and symmetrically affected, and exx)lains this predisposition by the fact that as corresponding teeth are usually cal- cified at the same x^eriod and pursue the same order of development, so the same morbid j)rocesses are commonly manifested in the same locations of corresi^onding teeth. The Vital or Inflammatory Theory of Caries. — Galen (a.d. 131) looked upon dental decay as being caused by a disturbance in the func- tions of nutrition. He said, "The lack of nutrition makes the teeth weak, thin, and brittle, while an excess of nutrition excites an inflammation very similar to that of the soft parts." Ambroise Pare (1579), the noted French surgeon, held to the theory of the inflammatory nature of dental caries. He says, in discussing the sub- ject of toothache, "These organs, after the manner of other bones, suffer from inflammation, quickly suppurate, and become rotten." Fauchard believed with Galen that caries was caused by vital or in- flammatory action, and described seven forms of the disease, — viz., scor- butic, variolous, scrofulous, moist or putrid, dry, superficial, and deep ; the latter form giving rise to severe pain. He assumed that there must be two causes for caries, as for all other diseases of the teeth, one of internal origin, producing internal caries; the other external in origin, and producing external caries. The internal causes, he stated, were referable "generally to the quantity and quality of faulty, acrid, or corrosive lymph, which acts upon their roots, attacking their external and internal surfaces." The latter doubt- DENTAL CARIES. 137 less referring to the root-canal and i)ulp- chamber. This variety, he stated, was difficult to recognize, from the fact that it is concealed from view by the gums and the alveolus. The external causes he does not ex- plain, but said these attack the outer portions of the tooth, — viz., the enamel, occasionally the neck, and the roots. The prevailing opinion of the medical men of this period was that caries of the teeth was due to inflammation, or, in other words, to vital action; that it was a true disease of dentin, the term "Odontitis" being given to it. Upon this supposition the researches of Fauchard, Bourdet, Jourdain, Hunter, Fox, Bell, Cuvier, Duval, Linderer, Meckel, etc., were conducted. This theory was revived by Newmann (1862), while Hertz and Abbott later attempted to confirm it, but with indifferent success. Jourdain (1766) believed with Fauchard in the exclusively vital or organic nature of the affection, which was at times inflammatory. Hunter (1778) maintained that the disease was a vital process, characterized by inflammation and gangrene, and somewhat analogous to caries of bone. He said, '^It does not arise from internal injury or from menstrua, which have the power of dissolving part of a tooth, but we may reasonably sup- pose that it is a disease arising originally within the tooth itself." He does not, however, seem satisfied with the idea of the analogy be- tween the carious i^rocess as observed in bone-tissue and in tooth -substance, as it does not satisfactorily explain the phenomena of gradual decomxDO- sition and loss of tissue with the formation of cavities. Upon this point he says, "The most common disease to which the teeth are exposed is such a decay as would appear to deserve the name of mortification. But there is something more ] for the simjDle death of the part would produce but little effect, as we find that the teeth are not subject to x)utrefaction after death, and therefore I am apt to suspect that during life there is some operation going on that produces a change in the diseased i)art. It almost always begins externally {external caries) in the small part of the body of the tooth, and commonly appears first as an opaque white spot. This is owing to the enamel losing its regular crystalline texture and being reduced to a state of powder from the attraction of cohesion being de- stroyed, which j)roduces similar effects to those of powdered crystal. When this has crumbled away the bony part of the tooth is exposed, and when the disease has attacked this part it generally appears as a brown speck." He also claimed that occasionally the disease originated in the dentin (internal caries), and that in this case the tooth assumed a shining black- ness from the dark color being seen through the remaining external shell of the tooth, which U]3on opening is found leading to the pulp-canal. Fox (1806) expresses the belief that "the diseases to which the teeth are subject have their origin in inflammation." In writing of the proxi- mate or direct cause of caries, he considered it to be "an inflammation in the bone of the crown of the tooth, which on account of its peculiar structure terminates in mortification." This process, he believed, was established through inflammation of the dental pulp and lining membrane 138 OPERATIVE DENTISTRY. of the pulp-clianiber (membrana eboris). He evidently considered tlie pulp-membrane as analogous to the periosteum, and confounded necrosis with caries ; for he stated that if the inflammation was severe in the pulp- membrane, nutrition would be arrested in circumscribed areas, as in peri- ostitis, thus causing death of portions of the dentin, which would after- wards decomj)ose and form cavities of decay. Bell (1831) maintained that dental caries was a species of gangrene, and that ''the true proximate cause of dental gangrene was inflammation." He did not believe that caries was ever caused by eodernal agencies which acted upon the enamel, but was due to internal causes which produced death of portions of the dentin. He defines dental gangrene as '^ mortification of any part of a tooth, producing gradual decomposition of its substance." Further he says, "The situation in which gangrene (caries) invariably makes its first appearance is immediately under the enamel, upon the sur- face of the bone (dentin)." This, he thought, was explained by the struc- ture of the teeth and the nature of the disease. "As the vessels and nerves which supply the bone of the teeth are principally derived from the internal membrane (pulp), -it is natural to conclude that in so dense a structure the organization would be less perfect in those parts which are farthest removed from its source, and that in the same portion they would be less capable of resisting the progress of mortification." With regard to the progressive character of the disease, he thought this could only be ex- plained by following the same reasoning. "When a portion of any of the other bones loses its vitality it acts as an extraneous body, producing irritation in the surrounding parts, and a process of absorption is set up in a line of living bone in contact with it in order to effect its separation. A similar effort appears to me to be made in gangrene of the teeth, but with a very different result, in accordance with the difference in the structure of the two seats of the disease. When a portion of the tooth is killed by inflammation it excites, as in the other case, an increased action in the vessels of the surrounding portion of bone ; but that very -action, which in such bones as possess greater vital power becomes remedial by promoting the removal of the cause of irritation, produces in the present case the continued extension of the disease ; for the irritation thus excited, instead of effecting the removal of the part by absorption, as in other necrosed bones, at once destroys its vitality and renders it only an additional por- tion of dead matter to that which had already existed. This, in its turn, becomes an extraneous and irritating body to the surrounding bone, in which the same action is set up and the same mortification produced, and thus portion after x)ortion is successively irritated and killed, until the whole crown of the tooth is destroyed." Fitch (1829-35), in both editions of his work, expresses substantially the same view as did I^eumann, Hertz, Koecker, and others. Koecker says, "Caries of the teeth must be considered as similar to gangrene in other parts of the system. And when we speak of caries as a disease we mean that diseased action in the bony structure of the living tooth produced by chemical irritation of its dead and rotten parts. DENTAL CAEIES. 139 "Hence it is indispensable that we should make a due distinction be- tween caries considered as a disease in the tooth and the effect of that dis- ease, — viz., mortification and putrefaction of its whole structure. Caries, in fact, is that state of the tooth in which mortification has taken place in one part, and inflammation in the part contiguous to it, the former origi- nally produced by the latter, and the latter continually kept up by the former. ' ' Koecker, however, maintained that there were two forms of caries, one beginning upon the external surface of the tooth, and the other having its origin within. The latter variety he looked upon as analogous to an abscess of the bone, for he says, "It (the disease) never proceeds so far towards the cavity containing the nerves as to render this membrane alto- gether uniDrotected by the bony structure before it has penetrated through the external osseous parts, including the enamel, and has thus formed a natural outlet for the bony abscess." Abbott (1879), Heitzmann, and Boedecker (1886 and 1888) made the attempt to revive the vital theory of caries. Abbott describes caries oc- curring in a vital tooth as "an inflammatory process, which, beginning as a chemical process, in turn reduces the tissues of the tooth into embryonic or medullary elements, evidently the same as, during the development of the tooth, have shared in its formation ; and its development and inten- sity are in direct proportion to the amount of living matter which they contain, as compared with other tissues." He opposed the idea that micro-organisms in any sense produced caries ; that these organisms did not penetrate the basis-substance of the tooth, "but appeared only as secondary formations, owing to the decay of the medullary elements." These authors maintained with the most positive assertions that "there occurs a primary inflammation in dentin, independent of pulpitis or iDeri- cementitis, running its course in the middle of the dental tissue, and leading, as all inflammatory iDrocesses do, either to a new formation or to destruction by supijuration." They explained the process as follows : ' ' Inflammation causes first a solution of the lime-salts, and afterwards a liquefaction of the basis-sub- stance, both in bone and dentinal tissue. The result will be the appear- ance of globular spaces or bay -like excavations, which exhibit medullary corpuscles, or sometimes clear protoplasmic masses corresponding to the embryonal stage of the inflamed tissue. . . . By the breaking apart of these medullary corx^uscles pus may be formed in the middle of the dentin, thus representing an abscess independently of the pulp-tissue ; or, on the other hand, a healing process may take place through the redeposition of lime-salts." These- views were never adopted by the pro- fession in general, as they were based upon alleged facts which were entirely foreign to the teaching of the best authorities in morphology, histology, and pathology, and, furthermore, others were not able to demon- strate them. The Worm Theory of Caries. — Just when or by whom the theory that worms were an essential factor in the origin and develoiDment of 140 OPEEATIVE DENTISTRY. caries is not known, but it is certain that for many centuries they were regarded as the cause of the disease, and various remedies were employed to destroy them or drive them out. Scribonius used fumigations, Ebu- Sina employed the seeds of henbane, leek, and onions. Musetanus (1114), Krautermann (1732), Euyleman (1824), Kremler, and many others recom- mended similar measures. (Miller.) Whether this theory arose as the result of imperfect observation or from a deliberate intention to deceive, history does not enlighten us. The chances are, however, that it was invented by some charlatan who desired to defraud the public and thereby fill his purse. This theory is commonly believed in China at the present day, and their dentists i)retend to remove such parasites from the teeth. The worms, which are artificial, are dex- terously placed in the mouth of the patient by the dentist during his manipulations, and then extracted and held up to the gaze of the wonder- ing but satisfied victim. Fauchard (1728) took infinite pains to discover the worms which were supposed to be the cause of the disease, and the odontalgia which was a frequent accompaniment of the disintegration of the tooth, but failed to discover them either in the carious dentin or in the salivary calculus. Pfaff (1756) discovered worms in the mouths of i)ersons who ate decay- ing cheese, but he was ' ' not able to observe that these worms had pro- duced toothache by gnawing." (Miller.) The Putrefaction Theory of Caries.— Pfaff (1756) was the first to advance the theory that dental caries was caused by putrefaction. He says, ''Eemains of food which undergo putrefaction between the teeth occasion decay of the teeth." Ficinus (1847) attributed dental caries to a putrefaction induced by certain minute infusorial animalcules which live in the mouth, and to which he gave the name Denticola. He believed these organisms produced a kind of putrefaction which first attacked the enamel cuticle, then pro- ceeded to destroy the enamel, and afterwards the dentin. The process of putrefaction requires an alkaline reaction, but he does not explain the dis- appearance of the calcium salts, which require acids for their solution. (Leber and Eottenstein. ) Klencke (1850) maintained the theory of putrefaction as the cause of caries, but divided caries into two distinct Yarieties,— central caries and peripheric caries. The former, he stated, has its origin in the pulp-cavity, the latter in the external portions of the teeth. Peripheric caries he divided into three different forms : 1. Soft caries (caries acuta), caused by the agencies of putrefaction, dental animal cula, denticole hominis. 2. A soft caries (caries acuta), due to the proliferation of a s^egetable parasite called Frotococcus dentalis. 3. The so-called dry caries (caries chronica), in which the parasites have no part ; this form being caused by the chemical action of acids upon the dental tissues. The Chemical Theory of Caries. — For many years, and up to a very recent period, the acid theory of decay received the support of a large DENTAL CARIES. 141 majority of the profession. In fact, it was the prevailing theory until the researches of Miller proved the disease to be caused by the zymogenic bacteria. Many of the advocates of the ''acid theory" taught that the teeth when once formed were not susceptible to change in structure, and that consequently they were passive in the hands of the disease 5 that the cause of caries was a purely chemical one, based upon the known fact of the af&nity of acids for calcium salts. Although the chemical theory may be said to be of modern origin, it nevertheless received its first suggestions from some of the older writers. According to Miller, Paul, of ^gina (636), first suggested the idea that acids jnight cause caries. He says, "In order to preserve the teeth pre- cautions should be taken against the spoiling of food in the stomach, since the frequent vomiting resulting from it is very injurious to the teeth." Carabelli is authority for the statement that the first experiments in regard to the action of acids upon the teeth were made by Berdmore (1771) with nitric and sulphuric acids. Pasch (1767), Biicking (1782), Becker (1808), and Eingelmann (1824) all attributed injurious effects to some foods and acids. (Miller. ) Harris (1830) was the first writer to announce his belief that caries was caused by a purely chemical process, the result of the action of acids within the mouth acting upon the calcareous material of the tissues of the tooth. Robertson (1835) combated the vital or infiammatory theory of the disease, and stated that caries was caused by a chemical decomposition of the dental tissues by the means of acids, the acids being formed in the mouth by the dissolution of food particles. Linderer (1837) considered caries to be due to a purely chemical process induced by the oral fluids, and combated the inflauimation theory, for, ' ' since dentin contains no blood-vessels, inflammation in this tissue is not conceivable." He also denied the existence of the so-called internal caries. Regnaud (1838) upheld the pure chemical theory of caries, considering the disease to be the result of the destruction of the dental tissues by acids formed within the mouth. He further stated that silk ligatures wound around the teeth, when left for a considerable i)eriod, cause tlie destruction of the enamel, while caps covering the teeth, whether made of wax or some metallic substance, promote their destruction, and human teeth, artificial sets, and individual teeth made from ivory also undergo destruction. Westcott (1843) proved conclusively by a long series of experiments that acids, both vegetable and mineral, act more or less vigorously upon the calcified structures of the teeth. AUport, a few years later, conducted a similar series of experiments with the vegetable and mineral acids, and arrived at substantially the same conclusions. Desirabode (1846) recognized two forms of caries, one external, which 142 OPERATIVE DENTISTRY. is caused by a chemical destruction acting from without inward, and the other internal, arising from some injury to the pulp or from a congenital defect in the dentin and developed spontaneously from within outward. Tomes (1837) was contemporary with Eobertson, and in his earlier writings his views were quite similar to those of Klencke. In his later work (1873) he concluded that caries was the effect of external causes in which the so-called vital forces play no part ; that it is due to the solvent action of acids which have been generated by fermentation going on in the mouth, the buccal mucus probably playing no small part in the matter ; and when once the disintegration is established in some congenitally de- fective point, the accumulation of food and secretions in the oral cavity will intensify the mischief by furnishing new supplies of acids. In his third edition he states that the buccal organisms have no small share in the matter of causing the disease. Tomes was the first to accurately describe the histologic alterations which take place at the seat of caries. These changes in the enamel he thought were caused in the majority of cases by imperfect development, with a greater porosity of the tissues, the porosity increasing with the jDrogress of the disease. The most remarkable changes were found in the canaliculi of the dentin. In cross-section they were seen to be surrounded by a thickened sheath, having a tobacco-pipe-stemmed appearance. In completely decalcified dentin the canaliculi with their enclosed soft fibrils — Tomes' s fibrils — remain free in the softened mass. In the more advanced stage of the disease he found these elements losing the sharpness of their contour and assuming a finely granular appearance. When the progress of the disease was very rapid, the dentinal sheaths presented varicosities and globular swellings. These pathologic changes proceed along the canaliculi towards the pulp, giving usually to the carious or infected portion of the dentin the form of a brownish cone with its base turned towards the enamel. In those cases in which a more extended surface of the enamel was involved, and where the destructive process was rapid, the cone existed only incom- pletely or was entirely wanting. Around the cone of discolored dentin a zone of relative transparency existed in which the canaliculi contained caiciiied dentinal fibrils. These changes were attributed by Tomes to organic or vital reaction of the dentin against the i^athologic irritation induced by the caries, and he believed retarded or arrested the progress of the disease. Oudet (1862) described two distinct forms of caries, — viz., external and internal. The former he believed to be caused by the action of acids upon the inorganic elements of the tooth, while the latter was the result of in- flammatory action occurring within the substance of the dentin, which secondarily involved the contiguous portion of enamel. Watt was perhaps the most conspicuous and aggressive advocate of the purely chemical theory of dental caries. He maintained that caries was caused by mineral acids principally, though he did not exclude the action of the organic acids, and insisted that the different colors seen in caries was the result of the action of these mineral acids, — viz., nitric, pro- DENTAL CARIES. 143 ducing white decay ; sulpliuric, black decay ; and chlorohydric, the intermediate colors. Taft in his earlier writings favored the chemical theory of caries. In his 05)inion, ' ' acid mucus and saliva, vitiated secretions, products of de- composition of animal and vegetable matter in the mouth, galvanic action, and mineral and vegetable acids, were the chief causes of dental decay." Schenckler believed most strenuously that acids produced caries, for he says, ''Be it repeated, where there is no acid no caries is possible." Baume stoutly maintained the correctness of the chemical theory, and as strongly opposed the parasitic theory. He said, ^^Tlie fungi are the result of the caries.''^ Magitot (1867), in his "Treatise upon Dental Caries," advocated the purely chemical theory of caries, claiming that the disease was caused by the acids contained in the saliva, or formed in the mouth by fermentation. He states as his conclusions, reached after a long series of observations and experiments upon natural teeth and those carved from ivory, under both natural and artificial conditions : 1. That dental caries is a purely, chemi- cal alteration of the enamel and dentin. 2. That the disease always progresses from the external surface of the organ inward, attacking first the enamel, second the dentin, and third the pulp, and that the existence of internal caries cannot be fairly pro\ed. 3. Disorganization of the enamel is a purely passive chemical process. 4. That in vital teeth there is developed between the caries of the dentin and the pulp a "cone or white zone formed by a mass of canaliculi obliterated in consequence of a formation of secondary dentin." This he terms the cone of resistance, and looks upon it as an effort of nature to resist or retard the progress of the disease. 5. That artificially produced caries presents the same phenom- ena as natural caries, with the exception of the evidences of organic or vital resistance. The Electro-Chemical Theory. — This theory was promulgated by Bridgman (1861-63), and endorsed by the Odoutological Society of London. The discovery by Faraday of the simple galvanic battery — viz., that a copper or zinc rod, with one end immersed in a dilute solution of sulphuric acid in water and the other exposed to the atmosphere, soon became polar- ized, and that at a point on the rod corresx^onding to the surface of the liquid the metal was gradually eroded and the material carried up the rod and deposited upon the portion exposed to the atmosphere, the acid forming one element of the battery, and the oxygen of the atmosphere the other — suggested to the mind of Bridgman that here, perhaps, was the solution of the vexed question of the cause of dental caries. He there- upon instituted a series of experiments upon teeth out of the mouth under conditions as nearly like those obtaining within the mouth as he could compass, with the result of producing caries artificially, which in appear^ ance was identical with that produced out of the mouth by acids, and in general features corresponded to the microscopic appearance of natural caries. He argued from this, applying the principles involved in the discovery of Faraday, that a tooth in the living body was always polarized, and had 144 OPERATIVE DENTISTRY. well-establisli'ed electric currents, that the root of the tooth when invested with the glim and alveohis, like the end of the rod immersed in the dihite sulphuric acid, possessed electro-positive qualities, while the crown of the tooth, like the free end of the rod, being exposed to the atmos- phere, had electro-negative qualities, consequently each tooth was a minia- ture galvanic battery, and whenever fluid or moist pulpy material was permitted to remain undisturbed in one position, as in the sulci and approximal spaces, for a few hours, the electric currents, which are con- stant, decompose them, and as a result acids are formed which attack the lime-salts of the tooth, and caries is established. He further claimed that the insertion of metal j^lugs within the teeth increased the galvanic action and also accounted for secondary caries. Palmer, Chase, and Flagg endorsed the views of Bridgman in reference to the production of secondary caries, and becanie the sponsors of what is known as the New Departure Theory in relation to the relative values of the various filling-materials as conservers of tooth-structure. These gentlemen instituted a long line of experiments to establish the position, in the electro-chemical series, of dentin with the various filling-materials. These experiments resulted in the demonstration of the following scale : Electro-negative : gold ; amalgam, tin, gutta-percha, dentin, oxychloride of zinc -^ electro-positive. The strongest electro-motive force or electric action is therefore gen- erated by a combination of gold and dentin, and in a decreasing ratio amalgam and dentin, tin and dentin, gutta-percha and dentin. Palmer claimed that these materials in the order named above possessed a com- patibility with tooth-structure in an increasing ratio, — viz., gold being the least compatible, and the ratio increasing to the bottom of the list. These authors and their followers have claimed further that the varia- bility in the structure of the teeth plays an important part in the liability to secondary caries ; teeth of low organization — "of greater porosity" — furnishing the most favorable conditions for a recurrence of the disease after the tooth had been filled, and those of the highest organization offering the least favorable conditions. Moisture is necessary in order to establish galvanic action between the filling- material and the dentin. This moisture is furnished by the fluids of the mouth which act at the margins of the filling, but it has been claimed that the tooth itself also furnishes moisture through its tubuli which in teeth of low organization would be sufficient to establish galvanic currents between the tooth and the filling-material, followed by decomposition of the fluid, the formation or liberation of acids, and decalcification of tooth-structure. The Germ Theory. — In discussing the various relations of micro- organisms to the process of fermentation, it has been frequently suggested that caries of the teeth might be, in part at least, caused by the action of micro-organisms. Erdl (1845) was the first to definitely state that dental caries was caused by parasites. These, he claimed, formed upon the crown as a delicate, colorless membrane, composed of cells, which later became more irregular and their nuclei more distinct. Miller thinks that inasmuch as Erdl em- DENTAL CAEIES. 145 ployed muriatic acid to isolate the ''caries matter," that it is C[uite prob- able that the delicate membrane which he obtained was nothing more than ^asmyth's membrane. Erdl applied creosote and nitric acid to destroy the parasites and prevent the progress of the disease. His method was first to apply creosote until the ' ' caries matter' ' was impregnated with it, then nitric acid, the latter immediately producing a violent and comxDlete decomposition of the creosote and of the parasites saturated with it. Ficinus, in 1847, suggested, as we have already seen, that the organisms of putrefaction — his denticolce — were the active agencies which produced the disease. These, he claimed, proliferated in Nasmyth's membrane, which they destroyed ; they next attacked the material between the enamel prisms, thus decomposing this structure and penetrating the dentin, which they destroyed in the same manner. Klencke (1850) discovered another parasite in the human mouth, which he denoininated protococcus dentalis, and claimed that this fungus i^ossessed the power of liquefying enamel and dentin. He says of it that it '''softens and destroys dental substances, and is nourished by their chemical elements." The first extended study of the organisms which are found in the mouth was undertaken by Leber and Rottenstein, and the results of their labors were published in 1867. These authors believed that there were two forms of caries, one M-hich they denominated central caries, having its origin in the cavity of the pulj), but an exceedingly rare form, and another to which is applied the term external caries, having its origin in the enamel, and caused by external influences. In reference to central caries, they presented a single case in illustra- tion, in which three teeth (two superior and one inferior incisor) in the mouth of a lady twenty-one years of age had lost their vitality from a traumatism, — a fall in early childhood. The teeth were blue in color, but there was no evidence of caries having penetrated from the surface. "In piercing the xDOsterior face of one of these teeth it was found completely softened, even to the enamel, and the tissues had a brown color. The root itself was hollowed to a considerable extent. The same was found to be the case with one of the other teeth. The third, whose color was not so marked, and which caused no unpleasant sensation, was let alone." Microscopic examination was not i^ossible, hence doubt must exist in relation to the supposition that caries did not originate from some micro- scopic defect in the enamel. These authors do not attempt to explain the cause which produced the central caries (%), but say, ' ' We believe that there exist cases where the dental tissues are attacked and destroyed from the cavity of the pulp ; but these cases are extremely rare, and the conditions of their production are uot yet well understood, except, perhaps, the previously necessary death of the tooth." With regard to external caries, they were of the opinion that the disease commences as a purely chemical process, but that as soon as the enamel is dissolved and the surface of the dentin exposed the elements of the lepto- thrix buccalis enter and penetrate the dental canaliculi, enlarging them, 10 146 OPERATIVE DENTISTRY. and thus increasing the facilities for the penetration of the acids which dissolve the lime-salts. Weil (1880), writing in support of Leber and Eottenstein's view of caries, says, '^ Decay generally begins from without, and must, therefore, first make its way through the enamel-cuticle. "It is highly probable that the fungus {leptothrix buecalis) bores directly through it. The fungi now proceed farther into the enamel, and force its prisms apart, gradually disorganizing its structure. From the enamel they i3enetrate into the tubules of the dentin, which are often en- larged by them to two or three times their original size, at the same time dissolving the calcium salts." Arkdvy stated the disease was "brought about by chemical action, in which the invasion of nosogenous fungi play an essential part." Milles and Underwood, in a paper presented to the International Medical Congress, held in London in 1881, gave new interest to the germ theory of dental caries, and marked the most important advance made in the discovery of the causes of the disease up to this time. The work of Leber and Eottenstein had found but few advocates, and had only stirred a passing interest in the subject, as the profession in general seemed satisfied with the acid theory of the disease. The marked success, however, of Lister (1865-69) in the treatment of wounds, which was based upon the discoveries of Pasteur in relation to the organisms of the various ferments, added new interest, and stimulated investigation into the theory advanced by Leber and Eottenstein of the etiology of dental caries. Koch (1881) added greatly to the facilities for observing these micro- organisms by the introduction of his improved methods of staining, and made it possible for later investigators to escape the errors into which their predecessors had fallen. Milles and Underwood, noticing the constant presence of micro- organisms in decaying dentin, and the equally constant enlargement of the dentinal tubuli, came to the conclusion that in the i^rocess of dental decay "two factors were always in operation, — first j the action of acids, and second, the action of germs. This theory, which, for the sake of distinction, may be called the septic, is rather an amxDlification of the chemical theory than a contradiction of it. They say, "Most probably the work of decalcification is entirely per- formed by the action of acids, but these acids are, we think, secreted by the germs themselves, and the organic fibrils upon which the organisms feed, and in which they multiply, are the scene of the manufacture of their characteristic acids, which in turn decalcify the matrix and discolor the whole mass." In reference to caries of cementum they say, ' ' From our observations on cementum to which caries has extended, we conclude that the process is very similar ; the bioplasmic contents of the lacunae and canaliculi afford food and lodging for the organisms, which multiply, and when sufficiently numerous decalcify the surrounding bone so that each lacuna loses its out- line and extends in all directions." DENTAL CARIES. 147 Miller (1882) anuonnced the results of a series of experiments which, he had conducted in relation to the active causes of dental caries, that it was his opinion that the first stage of the disease consisted of a decalcifica- tion of the tissues of the teeth by acids which are, for the greater part, generated in the mouth by fermentation. In this he agrees with Leber and Eottenstein, and partiallj^ with Milles and Underwood. In his later studies, which were published in the Independent Prac- titioner, 1884 and 1885, he carried the subject much farther, and arrived at conclusions which have been generally accepted, and now form the basis of the j)reseut teaching upon this subject. He says, in summarizing his work (1884), — ^'1. I convinced myself by the examination of some thousands of slides of carious dentin that micro-organisms were always present, and that they, without any doubt, were the cause of various anatomical changes which were found to take place in the structure of the dentin during caries. (Here, of course, the question of priority does not suggest itself ; Leber and Eottenstein, as is well known, were the first to give definite expression to this fact.) '^2. I proved, at the same time, that the invasion of micro-organisms was not, in the large majority of cases, simultaneous with the softening of the dentin, but that large areas of softened dentin could be found that contained no fungi. ' • Of all those who examined my preparations in America, no one, what- ever his theory, ever once denied this fact. I concluded from this that the softening of the dentin went in advance of the invasion of the organisms. ' ' 3. I determined, by analysis of masses of carious dentin sufficiently large to give reliable results, that the softening of the dentin is of the nature of a true decalcification ; that the decalcification of the outer layers is almost complete and diminishes in degree as we advance towards the normal dentin ; furthermore, that the same relations maintain in dentin softened in a mixture of saliva and bread, or in weak organic acids ; also, that in a mass of carious dentin the lime-salts had been removed to a much greater extent than the organic matter. "4. I maintained from the first that the softening of the dentin was produced by acids for the most part, generated in the mouth by fermenta- tion. I had, however, no proof of this. "5. I proved that fungi exist in great numbers in the human saliva and in carious dentin, which have the power to produce acid under conditions which are constantly present in the human mouth. I determined this acid — for one of the fungi at least — to he the ordinary ferment, lactic acid. ^■6. I produced caries artificially, which under the microscope cannot be distinguished from natural caries, by subjecting sound dentin to the action of these fungi in these fermentable solutions. "7. I determined the influeuce of various antiseptics and filling-mate- rials upon the fungi of caries. ' ' 8. I isolated various forms of these fungi, and determined, in part, the conditions most favorable to their development, their characteristic re- action upon gelatin, their physiologic action, their effect when inoculated 148 OPERATIVE DENTISTRY. into the system of lower animals, and their possible connection with certain obscure diseases generally attributed to the carelessness of the dentist." J. Sim Wallace * (1899) contends that caries is in no wise an inherited affection, nor is heredity a predisposing factor, but that certain inherited l^eculiarities of the teeth might favor the lodgement of food and micro- organisms and thus predispose to caries ; and that the environment of the teeth and consequent liability to caries is similar in certain families and races, on account of the similarity in diet and other customs. An important factor in the predisposition to caries lies in the relative lodgeability of the various food-stuffs. He believes the fibrous food-stuffs have a detergent action upon caries, in that these foods are less liable to acid fermentation. Comparing the conditions of the mouth following a meal made from flesh of any kind and that following a meal made from starchy foods, a marked difference is noticed in their relative cleanliness. In the former the mouth is comparatively clean, only a few fibres remaining between the teeth, and these easily removed, while in the latter the inter- approximal spaces and the fissures of the teeth are packed full of fer- mentable material, which is difficult to thoroughly remove, and thus are established all the conditions which are most favorable for the production of lactic acid fermentation and the decay of the teeth. Mouth-Bacteria and Carbohydrates. — The chief source of nourish- ment for micro-organisms in the human mouth, according to Miller, is furnished by two groups of substances, the carbohydrates and the albu- minoid substances. These are almost constantly found in the human month, either in the sulci and fissures of the teeth, in the approximal spaces, or upon their free surfaces. These substances are readily acted upon by the zymogenic and saprogenic bacteria. In all forms of fermen- tation there is a limit under ordinary circumstances to the quantity of the waste products produced by zymogenic bacteria. Black states : '' It is an established law that the waste products of an organism become poisonous to that organism when they have collected in a certain quantity. This is true of urea in the animal, it is true of alco- hol in the vinous fermentation, and Miller found it to be true of the organism causing caries. When lactic acid has accumulated in certain quantity (this amount not yet definitely determined) the further develop- ment of the organism is interfered with. Their power to go on producing lactic acid in the depths of the dentin is accounted for by the formation, from the lime-salts of the tooth, of the lactate of lime, which does not in- terfere with the further development, and, in fact, is equivalent to a removal of the waste i)roduct. Long before the existence of a sj)eQial organism in lactic fermentation was known, it had been found that by adding chalk or other form of lime the fermentation could be continued and much more lactic acid produced. Following up these facts. Miller has analyzed carious dentin and found it to contain calcium lactate. ' ' From the foregoing facts the student will readily understand why, as a * The Cause and Prevention of Decay in Teeth. DENTAL CARIES. 149 rule, dental caries wlien once establislied steadily progresses — more or less rapidly — until the tooth is completely destroyed. Were it not for the presence of the calcium in the structures of the tooth with which the lactic acid combines, forming lactate of calcium, the waste product of the organism — lactic acid — would soon destroy the bac- terium, and the j)rogress of the disease would be arrested. The carbohydrates in undergoing fermentation produce an acid reac- tion, while the decomposition or putrefaction of the albuminoid sub- stances j)resent an alkaline reaction. When these substances are mixed they are, as a rule, accompanied by an acid reaction. Consequently the reaction from the fermentation of food debris — which is usually composed of carbohydrates and albuminoids — will be found most often to give an acid reaction. This, however, is not an invariable rule, for Miller found that the reaction depended partly upon the nature of the food found in a par- ticular part of the mouth at tlie time and partly ui)on the particular kind of bacterium which was acting upon it. In the case of one bacterium which he examined in reference to this question, he found that when it was cultivated in a three per cent, solution of beef extract, in the presence of one-tenth per cent, of sugar, it gave a neutral reaction, but upon increasing the amount of sugar the reaction became acid, and upon diminishing it the reaction became alkaline. Miller, in another series of experiments instituted to determine the action of the mouth bacteria ui^on the carbohydrates, found that out of twenty-two varieties, sixteen in a very short time produced an acid re- action when cultivated in beef-extract, peptone-sugar solutions ; four under the same conditions gave an alkaline reaction, while in only two did the reaction remain neutral. Following this with another series of experiments with twenty-five mouth-bacteria, thirteen stomach-ba,cteria, and fourteen intestinal bac- teria, instituted for the same purpose, sixteen of the mouth-bacteria gave an acid reaction, four alkaline, and five inconstant results ; of the thirteen stomach-bacteria, nine produced an acid reaction, two alkaline, and two inconstant results ; of the fourteen intestinal bacteria, six gave an acid reaction, five alkaline, and three inconstant results. Miller, in his next series of experiments, undertook the task of demonstrating by qualitative analysis the character of the acids formed by the acid producing mouth- bacteria. It was generally believed up to this time that the lactic acid fermentation could not be brought about except in the presence of one specific micro-organism, — viz., the hacterium acidi lactici. Miller had dis- covered, however, some time previously, that severed forms of bacteria found in the human mouth were capable of forming lactic acid out of sugar. This discovery has since been verified and established by various investigators, as well as the fact that a large number of bacteria are pos- sessed of inverting and peptonizing properties. Out of eighteen different forms of acid producing bacteria, Miller found as a result of his labors that ten of them produced lactic acid. Among the other products of fermentation of these bacteria were formic, acetic, and butyric acids, ''the latter, however, in very small quantities." 150 OPERATIVE DENTISTRY. Lactic acid, however, requires for its production in the mouth, — 1. Substances which are capable of being converted into glucose, G3Hi20g, — viz., the three groups of carbohydrates, — glucoses, C,;Hj.,Ob; sac- charoses, C12II22O11 ; and amyloses, CgHj^O^. The carbohydrates of the glucose group which are most common in the food of human beings are grape-sugar (dextrose) and fruit-sugar (levulose), cane-sugar of the saccharose group, and starch, cellulose, and gum in the amy lose groui3. Hydration converts grape-sugar into two fermentable substances, levu- lose and dextrose, their chemical composition being the same, CgHijOg. This change is brought about by the action of such organized ferments as ptyalin and amylopsin. The conversion of starch into glucose is repre- sented by the following formula : ^eHw^s + ^1^ = ^J^vS-^q- "^ ° starch. Glucose. 2. The fermentable carbohydrates must' be acted upon by ferments capable of converting these substances into lactic acid. These ferments are constantly found in the human mouth in the form of various zymo- genic bacteria, while the necessary conditions for their growth and devel- opment — ^heat and moistuie — are ever present. The fungi have the power to cause the sugar to split up without the formation of carbon dioxide, a molecule of glucose, CgHjjOg, forming two molecules of lactic acid, 2C3Hg03, It is noticeable, however, that caries does not always progress with the same rapidity in the same individual or in different individuals ; that the character of the disease is not always the same ; that certain teeth are attacked, to the exclusion of others, while there is a marked differ- ence in the extent of the disease between individuals and in the same individual at different periods of life, and under varying conditions of health. The question very naturally arises as to the cause or causes for these differences. Are they due to the degree of vital resistance possessed hy the indi- vidual at the time, or hy individual teeth ? Or are there conditions operative within the mouth which favor the groivth of the lactic acid lyrodncing ferments at one time and retarding them at another f It is not at all improbable that in the multitude of mouth-bacteria some form inimical to the growth of lactic acid forming organisms may under certain conditions gain the as- cendency for a time, and thus in a measure control the production of the lactic acid ferment. The further study of these organisms may yet dis- cover such a bacterium which, introduced into the mouth, will retard or prevent the growth of lactic ferments, and thus solve the problem of the prophylaxis of dental caries. The tendency to caries is always augmented in certain forms of disease, like the continued fevers, tuberculosis, anaemia, and all wasting affections. These abnormal conditions of health not only reduce the vital resistance of the general system and lower the vis oiaturce of individual tissue, but they produce abnormal conditions of the buccal secretions which favor the growth of the zymogenic mouth-bacteria. It is therefore possible that both of these factors act together under the conditions indicated, not only to in- DENTAL CARIES. 151 crease tlie tendency to caries, but also the extent of the disease and the rapidity of its progress. Mouth-Bacteria and Albuminoids. — It is generally recognized at the present time that a great number of the bacterial forms possess the power of liquefying, digesting, or peptonizing coagulated albumin and collagen, which forms the basis substance of dentin and bone. Miller says, '^ By far the majority of mouth bacteria, in fact, of all bac- teria, possess an action similar to pepsin, in converting coagulated albu- min into soluble modifications." The bacteria possess the power of pep- tonizing these substances in either an acid, alkaline, or neutral medium, while pepsin acts only in the presence of acids, preferably hydrochloric. Albuminoid substances are, therefore, excellent media upon which to cultivate bacteria. Miller found the products of mouth bacteria cultivated upon albu- minoid substances to be the same as those developed from the i^utrefaction of organic substances in general. These are principally malodorous and noxious gases — sulphuretted hydrogen (H.S), ammonia (NH3), carbon dioxide (COJ — and numerous substances, such as formic, acetic, butyric, valeric, and other acids. He also found that four of the mouth bacteria which he examined would not grow upon coagulated albumin ; six had but a limited growth, while all the others ' ' developed comparatively well, in some cases com- pletely liquefying the albumin." It will thus be seen that the mouth bacteria are capable of producing dental caries, that certain of them possess the necessary proi)erties for forming acids, which, acting upon the lime-salts of the enamel, disinte- grate this tissue and thus permit the entrance of these organisms into the dentinal tubuli, where they continue the process by dissolving or abstract- ing the lime-salts from the dentin, and that afterwards certain other forms liquefy, peptonize, or digest the basis substance, thus removing the organic tissue and forming a cavity of decay. Bastyr (1885), in commenting upon the active causes of dental caries, says, ''As long as it cainiot be shown that the appearances observed in the decay of living teeth, decay of dead (x3ulpless) teeth in the mouth, and artificial caries show any appreciable diiferences, so long will every attempt to explain decay as a vital process be very difBicult." Black (1886), in discussing the germ theory of caries as promulgated by Miller, says, "The fungus has no power of attacking anything, or growing into anything, except it, be a thing that offers spaces filled with soft tissue, or openings into which it may grow as the vine grows through spaces in a lattice- work. " It is not the organism that makes the attack, but the products of the organism, the lactic acid. "When the dental tubules are once exposed, they form a protection to those filaments of the fungus which strike into them in the process of growth, and development occurs in that direction. Hence the continuous progress of caries when it has once fairly begun in the dentin. Then the growth will continue in any direction in which space is offered for the 152 OPERATIVE DENTISTRY. development of filaments. In this way the tubules become packed full of the organisms, and the surrounding dentin is always decalcified in advance of the growth of the fungus by the lactic acid produced. That this is the true explanation of the etiology of dental caries there is no longer a reasonable doubt." Gysi (1887), in writing upon the chemico-parasitic theory of caries, remarks, "As all my experiments and investigations upon this subject have presented facts which are consistent with it, I accept it as a satisfac- tory explanation of the etiology of the disease." Pierce (1888) endorsed this theory in the following words : "I am a firm believer in the fact that dental caries cannot progress without these low forms of life." Sudduth (1888) says, "Dr. Miller's theory of the formation of cavities by the action of a digestive ferment upon the basis substance of dentin has been the only theory ever advanced that explained the formation of cavities." Allan (1889) maintains that "the germ theory is the only one so far presented that clearly and satisfactorily accounts for the acid," and, fur- ther, that ' ' the ' germ theory' fully explains the distended tubules and the broken-down basis substance." Caries of the Enamel. — Up to a very recent period our knowledge of the phenomena of caries of the enamel has been very meagre. Miller, in his earlier descriptions of the phenomena, etiology, and morbid anatomy of dental caries, did not give a very clear and distinct idea of the modus operandi of caries in the enamel, but his later sug- gestions and observations, correctly interpreted, led the way to the more definite discoveries of Williams in the morphology and histologic anatomy of the enamel, described in Chapter III., Histology of the Dental Tissues, to which the student is referred. Williams (1898) found, in studying enamel structures, that in decalci- fying sections of fully formed enamel the acid attacks the interprismatic substance first, and the rods fall apart, proving conclusively that the sub- stance is one which is acted upon by acids, — viz., calcareous material, and 7iot an organic hasis substance composed of animal matter, but more readily acted upon than the enamel-rods themselves. If the process of decalcification was continued, the enamel-rods were attacked and the whole structure destroyed, leaving behind no evidence whatever of an organic matrix. Sections of enamel treated by a one per cent, solution of chromic acid — which does not destroy organic substances — left no trace of organic ma- terial ; hence it can be positivefy stated that fully developed enamel con- tains not the slightest evidence of an organic matrix. Williams, in his studies of caries of enamel, found zoogloea masses of micro-organisms adherent to the surface of the enamel, probably attached to the remains of the enamel cuticle and lining the surfaces of the cavities of decay. He says, "Lining the cavities or covering the surface where decay has commenced, there is always to be seen a thick, felt-like mass of acid-forming micro-organisms. This mass of fungi is so dense and adhesive as to make it highly improbable that the enamel is affected, DENTAL CARIES. 153 except in rare or special instances, by any acid other tlian that whicli is being excreted (lactic) by the bacteria at the very ]3oint where they are attached to the enamel. This thick, glutinous-like mass of fungi also prevents the excreted acid from being washed away, so that it exerts its full chemical power upon calcified tissue." This idea was first suggested by Ficinus as far back as 1847. Dilute lactic acid produced appearances upon sections of fully formed enamel that were identical with those produced upon this tissue in the progress of natural caries. Decalcification of the enamel proceeds most rapidly along the line of the enamel-rods when the process has once been established. The bac- teria growing into the spaces formed by the solution of the interprismatic cement substance cause fracture and dislodgement of masses of partially decalcified enamel-rods, and thus hasten the process of cavity formation. In cases of rapid caries, Williams found streptococci almost always present, while in caries of slow progress ("backward decay") the large cocci and diplococci were always found. In the direct caries of enamel the cavities are lined with leptothrix and thread-like forms. The leptothrix Buccalis maxima and the bacillus Buccalis maximus of Miller are nearly always found, the latter more sparingly. Beneath the felt-like masses of thread-forms, and lying in contact with the decomposing enamel in direct decay, and also in deep cracks and fis- sures in backward decay, there is invariably found a short, thick bacillus, usually constricted in the centre. Williams suggests that possibly the variety of the organism found in these forms of enamel decay may be the governing factors in the rapidity of the progress with which dissolution of the enamel takes place. In the light of these discoveries it may be stated with certainty that the first stage of dental decay is characterized by a softening of the enamel, which is brought about as a direct result of the presence of carbo- hydrates which undergo fermentation through the action of certain zymo- genic bacteria, and that these organisms are retained in protected positions through the formation of a gelatin-like substance secreted by themselves or certain other organisms present in the mouth, thus forming zoogloea masses which adhere to or become glued to the surfaces of the teeth. By this means the acid formed by the zymogenic organisms are kept in contact with the enamel and prevented from being washed away, as would undoubtedly be the case were it not for the presence of this protecting envelope, thus permitting the full chemical action of the acid upon the enamel to go on undisturbed. Caries of Dentin. — In studying the etiology of dental caries we have found that the same acid-jDroducing ferments or micro-organisms were accountable for the production, initiation, and i^rogress of the disease in all of the calcified tissues of the teeth, and that the saprogenic bacteria, or possibly the same zymogenic organisms, liquefied the basis substance and removed it, thus causing a gradual dissolution of these tissues until the entire organ is destroyed. The lactic-acid-producing organisms belong to the facultative variety of 154 OPERATIVE DENTISTRY. bacteria. This lias been proved by the fact that they grow and develop equally well upon the surface of the enamel wherever lodgement can be found, in the presence of the oxygen of the atmosphere, and in the tubuli of the dentin in which th(i oxygen of the atmosphere would be excluded by the presence of the fluids of the mouth. This fact explains the progress of caries which occasionally occurs under fillings having perfect margins, in which, for reasons that have seemed good to the operator, portions of decalcified dentin have been per- mitted to remain in the bottom of the cavity, but have not been thoroughly sterilized by dehydration and antiseptics. For the growth of micro-organisms three conditions are absolutely neces- sary, — heat^ moisture, and a proper soil or food-supply ; cut off any one of these and the organism will cease to develop. The permanent arrest of caries, therefore, from the therapeutic stand- point, sums itself up into, first, so preparing a carious cavity that the food- supply of the micro-organisms and the decalcified tissue is thoroughly removed, and, secondly^ in so inserting a plug or filling as to hermetically seal it. Without the ingress of moisture, or the presence of the elements from which the bacteria elaborate lactic acid, the progress of the disease must be arrested. Susceptibility and Immunity. — Susceptibility to caries has gener- ally been considered to be one of local environment, dependent upon the structural defects of the enamel and dentin and conditions which favored the development of the lactic-acid-producing micro-organisms. While immunity has been thought to be the result of perfectly developed dental tissues and conditions which retarded or prevented the formation of lactic acid, the degree of suscei3tibility, it was thought, was governed by the extent of the structural defects and the numbers and rapidity of develop- ment of the micro-organisms of decay. The investigations of Black (Dental Cosmos, May, 1895) and of Wil- liams (Dental Cosmos, March and April, 1897) have conclusively shown that dental caries is not dependent upon the structural defects or imperfec- tions of the dental tissues nor to their degree of calcification. Black determined by laborious and painstaking laboratory experimen- tation that human teeth show wide difierences in physical structure of both the dentin and the enamel, ranging from that in which the enamel is practically perfect in all of its parts to those which present grave imper- fections of its physical structure, such as imperfectly closed developmental grooves, which leave fissures, pits, and openings of various sizes and shapes. The dentin also presents marked deviations from a physical perfection of structure. In some instances the dentin is very perfect, in others the interglobular spaces are exceedingly numerous and the granular areas IDresent many physical imperfections. These investigators have both shown that these physical imperfections are in no wise a cause of dental caries, for among persons wholly immune to caries these imperfections are relatively as frequent as in those persons DENTAL CARIES. 155 who suffer from caries, and that even when the imperfections of the enamel are such as to expose the dentin, no decay has occurred in a life- time, as, for instance, in the imperfections of structure due to inherited syphilis and arrests of development caused by the exanthematous disease of early childhood, etc. Black * thinks these facts prove beyond a doubt that structural imper- fections, at most, only give greater oiDportuuity for the active agents of caries to do their work, and have no further relation to that cause. In other words, physical imperfections of the enamel and dentin are simply local predisposing causes of the disease. Teeth, therefore, which present the most faulty structure may not decay, and will not decay in persons who are immune to caries, while teeth of the most perfect physical structure will succumb to caries in persons who are at the time susceptible to the disease. The active agents of caries are to be found in every mouth, and in sufficient quantities to produce the disease, and yet in certain individuals there is a complete immunity through a lifetime, while in others there may be various periods of susceptibility and immunity which seem to have no discovered relation to the local environment or condition of the health. The formation of the gelatinous plaques or zooglea masses by the caries fungus, as shown by Williams to be necessary to start the i)rocess of caries in the enamel, are not found in all mouths, though the organisms may be there and growing. The power of the organism to form gelatin, according to Black, seems to depend upon something in the saliva, the nature of which has not been discovered. These facts seem to throw some light upon the subject by indicating the direction in which future investigation should proceed. At the risk of being considered over-sanguine, the writer suggests that a means of preventing caries will yet be discovered, and that it will be- in the nature of an antagonist to those organisms which have the power of forming gelatin in the oral fluids. Black is of the opinion that susceptibility is influenced by an inherited predisposition to the loss of the teeth, or of especial teeth at certain ages ; by changes of environment, either of climate or mode of life ; by the age of the individual, the young being most susceptible, while immunity usually comes with adult age ; and by the fluctuations of bodily conditions which change the character of the oral secretions. Phenomena of Caries of Dentin. — The invasion of the dental tis- sues by caries begins by the decalcification of the enamel, either in some fissure, pit, or crack, which may be only microscopic in size, or upon roughened surfaces which have given lodgement and protection to the zymogenic organisms, most commonly the approximal, labial, and buccal surfaces, as shown in Fig. 272, The margins of the cavity usually present more or less discoloration or opacity, while the enamel will be found softened by decalcification and * Dental Cosmos, September, 1899. 156 OPERATIVE DENTISTRY. broken down. Sections of teeth cut throiigli a cavity of decay in tlie enamel show immediateh' beneath an exposure of the dentin with soften- ing and discoloration. Closer inspection reveals, lying between the floor of the cavity and the pulp-chamber, several x)eculiarities in the color, the degree of decalcification, the transmission of light, and certain changes in the size and form of the tubuli. Pigmentation. — The color in ordinary caries at the surface of the cavity is yellowish brown, but it shades off as it reaches towards the pulp into the normal color of the dentin. In caries of rapid progress the color is white or yellowish white, while in caries of slow progress, or in arrested caries, the color is dark brown or black. The more rapid the progress of caries the lighter the pigmentation. It was thought at one time that the color was pro- duced by the carious process or by the micro-organisms. The fact, how- ever, that the discoloration can be easih' and perfectly reproduced out of the mouth, with teeth which have been acted upon to any considerable extent by acids, proves conclusively that it is not due to the process of caries nor to bacteria. To accomplish this. j)lace such teeth in water holding in solution a small quantity of sulphuretted hydrogen, fill the vessel, and place it in a dark closet to prevent decomposition of the solu- tion, and the tissues of the teeth, to a point as deep as that affected by the acid, will gradually assume a dark color. (Black.) Decalcification. — The degree of decalcification grows less and less from the surface of a carious cavity until normal dentin is reached. (See Fig. 273.) The outermost layers of the dentin will generally be found completely decalcified, the basis substance being soft and leathery, and having an odor like that of gangrenous lung-tissue. Beyond the line of jjartial decalcification is a transparent zone known as the zone of Tomes (Fig. 274), which its discoverer and Magitot have maintained was caused by vital action, or resistance of the tissue to the encroachment of the disease, and produced by the filling up of the den- tinal tubuli with calcific material, and thus making it more easily j^ene- trated by rays of light. It is in appearance very similar, both macrosco^^i- caliy and microscopically, to the senile dentin, the dentin of the crowns of teeth worn down by mechanical abrasion, and the roots of teeth which liave remained long in the mouth without dental decay. Miller, by quantitative analysis, has shown that it contains more calcium salts than the surrounding normal dentin. AValkhoff thinks that it is an evidence of vital or formative activity induced by the stimulation of irritation, causing the j)roduction of an intercellulai" substance at the surface of the cells and xjrimarily of their oifshoots. It will be noticed, also, as i^ointed out by Gysi, that the transparent zone which lies between the carious dentin and the pulp is continuous with a new formation of dentin— secondary dentin — upon the wall of the pulp-chamber (Fig. 275). Burchard thinks "these evidences point to the truth of Walkhoff's • explanation of the process, and indicate that the transparent appearance is the result of vital reaction."' Fig. 272.— Vertical section of deciduous molar, showing caries of enamel which started in a fissure, and of the dentin which had its origin in an approximal cavity of decay, x 8. Fig. 273. — Carious dentin from base (jf cavity. (V. A. Latham.) , 4il.t;i;. ^l, infected tubules; B, en- larged tubules ; C, infected interglobular spaces. Fig. 274. — Undermining caries of enamel, showing transparent zone of Tomes at A. (R. R. Andrews.) Ik t Fig. 276. — Dentinal tubules from infected dentin, showing enlargement of the tubules and the presence of micro-organisms within them. (Tomes.) DENTAL CARIES. 157 It is still, however, an open question as to whether the transparent zone is or is not a real zone of resistance to the encroachment of the dis- ease and effective in retarding its progress. Clinical observation and ex- FiG. 275. Longitudinal ground-section of crown of an inferior molar of a negro. This figure is drawn from a ground and polished section mounted in Canada balsam. (Gysi.) E, enamel ; D, dentin ; C, cement ; p, pulp-chamber; a, large decay, from the grinding surface; 6, small decay, from the mesial surface ; cs, 7one of septic invasion and discoloration; e, partially decalcified and discolored enamel around the carious cavity ; z, dark zones ; s', clearer zones ; z'p, oldest zones, where putrefaction of the tooth- cartilage begins ; c, outer transparent zone, or zone of Tomes ; sd, secondary dentin, caused by irritation ; s'd', secondary dentin deposited by normal physiological process, recession of the pulp. perience would seem to indicate that it has an effect upon the dentin which renders it more resistant to the progress of the disease. Expansion of the Tubuli. — Sections of carious dentin cut parallel with the long axis of the tubuli, which have been stained with fuchsin or 158 OPERATIVE DENTISTRY gentian violet, show these tubules to be considerably enlarged, with swell- ings or molecular expansions upon individual tubes (Fig. 276). Fig. 277. Fig. 278. Fig. 279. 8^ si-s a \ f^ Single tubule filled with cocci. (Miller.) 1100:1. Fig. 280. Decayed dentin, showing a mixed infection with cocci and bacilli. (Miller.) 400:1. Single tubule filled with rods. Single tubule showing a mixed (Miller.) 1100:1. infection with a pleomorphous bacterium. (Miller.) 1100:1. et Fig. 281. Longitudinal section of decayed dentin, showing infection with rod- and thread-forms. (Miller.) a, tubule distended, but walls still comparatively intact ; 6, d, tubular walls broken through and the dentin in a state of complete dissolution ; c, tubules out of focus. Circa 500 : 1. There is, however, no uniformity in the enlargement of the tubules or of the nodular expansions. Some tubules will be very much enlarged, Fig. 282.— Vertical section of infected human dentin, showing the presence of micro-organisms and enlargement of the tubules. (K. E. Andrews.) ^f' ' Fig. 283.— Transverse section of infected human dentin, showing the presence of micro-organisms and various enlargements of the tubules. (R. R. Andrews.) Fig. 284. — Vertical section of infected human dentin, showing tubules greatly enlarged and filled with micro-organisms. (R. R. Andrews.) Fig. 285. — Infected human dentin, showing confluence of enlarged tubules forming cavities which are filled with micro-organisms. (R. R. Andrews.) Fig. 286.— Oblique se(;tiou of infected human dentin, showing confluence of tubules forming larger cavities. (R. R. Andrews.) Fig. 2,87.— Infected human dentin, showing advanced state of infection. (V. A. Latham.) :< 100. A, A, A, micro-organisms in the tubuli. The dark portion shows decalcified and discolored areas of dentin. i--^ Fig. 288.— Transverse section of human dentin, sliowing pipe-stem appearance of infected dentinal tubules. (Tomes. ) Fig. 289.— Transverse section of dentinal tubules. (V. A. Latham.) X 1G2.5. The dark tubules show- infection with micro-organisms and the pipe-stem appearance described by Tomes. DENTAL CARIES. 159 while others will seem to be only slightly affected. "Walkhoff declares the dentinal tubuli are regularly enlarged, and that the varicosities appearing at irregular intervals are occasioned by the drying of the specimen. Upon further examination with higher powers of the microscope it will be discovered that the tubuli in the superficial, softened^ and decalcified dentin are filled with bacterial forms, cocci, rods, and threads, the coccus forms predominating. Fig. 277 shows a single tubule filled with cocci; Fig. 278, one filled with rods. Fig. 279 shows a mixed infection of cocci, diplococci, short and long rods, or infection with a pleomorphous bacterium (polymorphous). Fig. 280 shows several tubules in decaying dentin filled with a mixed in- fection of cocci and bacilli, while Fig. 281 shows a longitudinal section of decayed dentin which is infected with rod- and thread-forms. Figs. 282, 283, 284, 285, 286, and 287 show the micro-organisms as they appear in slides made from decaying dentin. In the deeper layers of decalcified dentin the bacteria become less and less in numbers, until they finally disappear. Beyond this non-infected point, however, there is a zone of partially decalcified dentin, the removal of the lime-salts being caused by the solvent action of the lactic acid pro- duced by the bacteria lodged within the tubules. Cross-sections of decaying dentin exhibit a very peculiar appearance of the dentinal tubuli, or rather of the sheaths of Xeumann (Fig. 288), which are, according to Tomes, greatly thickened, and the lumen partially obliterated, giving the section the appearance of having been built up of a multitude of tobacco-pipe-stems (Fig. 289). Such is the condition at a certain stage of their disorganization. In longitudinal sections examined at a later period the sheaths appear to break up into short lengths or sections, and are found twisted ; and^ finally, the whole tissue undergoes disorganization into minute granules, which are by degrees washed away by the fluids of the mouth. Disorganization of the Dentinal Fibres.— The contents of the tubuli — Tomes fibres — also appear to undergo disorganization and break up into pipe-stem sections or short rods (Fig. 290). This was first noticed by Tomes. This peculiar api)earance has not been satisfactorily explained. Tomes says, "These rods may be portions of consolidated fibrils, or they may be bits of the sheaths of ISTeumann, or they may be mere casts of the enlarged tubules." Wedl, however, thinks the statement that they are consolidated fibrils is not proved. Miller is of the opinion that they are calcified fibrils, as he has observed their rapid disappearance while viewing them under the microscope when the siDCcimen was treated with dilute sulphuric acid. Another peculiarity is also observed in the dentinal tubuli in the form of shining or glistening granules. These are seen occurring in the early stage of caries, and sometimes in the zone just in advance of the carious process. Some observers, Tomes, Magitot, and others, have thought them to be lime formations thrown out by the odontoblasts for the purpose of resisting the advance of the disease. Wedl, Black, and others looked 160 OPERATIVE DENTISTRY. upon them as fat-globules. Baume has shown conclusively, however, that these globules are not particles of fat, since they do not disappear when treated with sulphuric ether. Miller thinks these granular bodies cannot be lime formations thrown out by the pulp, for they are found in caries of pulpless as well as living teeth, but regards it as not improbable that they have the same origin as the rod-shaped (pipe-stem) formations found in the tubuli. PENETRATION OF CARIES. Generally speaking, the line of progress or penetration of caries may be stated to be in the direction of the tubuli, or, in other words, from the surface towards the pulp. This, however, is not universally the case, for occasionally cavities will be found which have been formed in a direction transverse to the tubuli. The conditions which favor the formation of such cavities are usually, if not always, due to faulty formation of the den- tin, interglobular spaces, thick granular layer, or other imperfections in the deposition of the calcoglobulin and its calcification. Such spaces offer admirable facilities for the penetration and growth of the micro-organisms and the lateral extension of the disease. Fig. 291 shows interglobular spaces filled with micro-organisms. In the ordinary form of caries the disease travels along the tubules by the penetration of the fungi into these open siDaces (Figs. 292 and 293), and exposure of the pulp takes place before lateral spreading has progressed to any great extent. This is espe- cially true of teeth of the best development, for observation proves that exposure of the pulp will occur in this class of teeth with the least destruc- tion of tissue. ''The more perfect the development the more completely will the penetration be confined to the direction of the tubules." (Black.) CARIES OF CEMENTUM, The etiology of caries of cementum is so nearly like that of decay of dentin that it hardly needs a special description, except that which grows out of the difference in the histologic structure. Decalcification is caused by the same micro-organisms that produce caries of dentin. The fungi first attack the calcified rods known as Sharpey's fibres, and penetrate to the cement- corpuscles and their canaliculi, decalcifying the surrounding tissue as in decay of dentin. The organic substance is then liquefied by the saprophytic bacteria and washed away. Fig. 290. — Longitudinal section of infected human dentin, showing the pipe-stem appearance of the tubules described by Tomes. (R. JR. Andrews.) Fig. 291.— Infected human dentin. (V. A. Latham.) X 162.5. A, micro-organisms in the tubuli; B, B, micro-organisms in the interglobular spaces. A Fig. 292. — Infected human dentin. (R. R. Andrews.) A, A, A, showing penetration of micro-organisms in the tubuli. Fig. 293. — Infected human dentin. (R. R. Andrews.) A, A, showing penetration of micro-organisms in the tubuli. CHAPTER IX. DENTAL CARIES (CONTINUED). Varieties of Caries. — The older writers were in tlie habit of dividing caries into several varieties, according to the physical signs presented bj^ the disease, believing that these signs represented distinct forms of the affection, which they classified as follows : caries humida, moist caries ; caries acuta, acute or rapid caries ; caries chronica, chronic or slow caries ; and cajHes sicca, dry caries or arrested caries. This classification of the disease is no longer used, as the aifection is now known to be one and the same from beginning to end, the differences in the physical signs being due to the differences in the character or perfection of the structure of the teeth, the conditions of the general health, the character of the oral secre- tions, and the hygienic conditions which prevail in the mouth. All of these factors have an influence upon the extent and the rapidity in the progress of the disease, and are responsible for the differences in the physical signs. Stages of Caries. — It is customary with most writers in describing dental caries to divide the disease into various natural periods or stages. Magitot divided the affection into three periods,— first, second, and tfih^d. The first period he confined to the dissolution of the enamel. The second period to the destruction of the dentin. The third period to the in- volvement of the pulp-chamber. A more exact division of the stages of the disease recognizes four dis- tinct periods or degrees of progression : First, superficial or incipient. Second, progressive. TJiird, deep-seated. Fourth, complicated. In the first, or superficial or incipient, stage (Fig. 294, A) the disease in- volves only the enamel or the cementum. This may be confined to the surface of these tissues or involve their whole thickness, forming a per- ceptible cavity, which may be more or less sensitive to sweets, acids, or thermal changes. In the second, or progressive, stage (Fig. 294, B) the enamel or the cemen- tum has been penetrated and the disease is extending into the dentin, forming a deeper cavity. The third, or deep-seated, stage (Fig. 294, G) represents a more serious involvement of the dentin, reaching almost to the pulp-chamber ; not, how- ever, exposing the pulp, but causing irritation and making it necessary to protect it by some form of capping before inserting a filling. In the fourth, or complicated, stage (Fig. 294, D) the disease has extended to the pulp-chamber, causing inflammation or death of the pulp. The rapidity with which caries sometimes progresses often makes it 11 161 162 OPERATIVE DENTISTRY. Fig. 294. Vertical section of a lower molar tooth showing stages of caries. impossible to distinguish the various stages one from another, while in such cases especially there is a lack of j)igmentation. This form of the disease, which is sometimes termed icMte decay (caries humida), not infre- quently in the course of a few weeks destroys one-half or more of the tooth and exi)oses the pulp. In the ordinary form of caries (caries acuta), sometimes designated as hroxon decay, the time required for the disease to penetrate from the enamel to the pulp- chamber is from six to eighteen months, while in that form known as hlack decay (caries chronica) the process is so slow that several years are required for the disease to penetrate to the pulp. Symptoms. — The symptoms of caries in its earlier stages vary from a mild drawing or gnaw- ing sensation to that of acute pain. These symp- toms are induced by the exposure of the dentinal fibrils to the irritating effects of sweets, acids, salt, changes of the temperature, and instrumen- tation. The character and severity of the symptoms vary with different individuals, and in the same individual at different times and under varying circumstances. Temperament has much to do with the char- acter and severity of the pain experienced by people suffering from dental caries. Individuals possessed of exalted nervous irritability suffer much more than others, while in the same individuals certain conditions of health, like anaemia, dyspepsia, nervous prostration, mental worry, or other causes which depress the vital forces, as chlorosis and pregnancy, often greatly increase the susceptibility to pain and render the symptoms of caries very acute. It is also a notable fact that many times in the first and second stages of the disease there will be great sensitiveness of the dental tissues, but as the process advances the sensitiveness diminishes until the pulp becomes involved . Under ordinary circumstances the superficial layers of carious dentin are much more sensitive than those which lie deeper. This is also true of normal dentin. The peripheral extremities of the dentinal fibrillte, or that portion of them which lies directly beneath the enamel and cementum, assuming that the fibilllse carry sensation, are much more sensitive than at their deeper parts. This is true of peripheral nerves everywhere. The irritation attendant upon the carious process greatly increases the sensi- tiveness of the fibrilljB, and produces what is termed hypersensitwe dentin. In certain individuals, however, the sensitiveness of their teeth is so slight that carious cavities can be excavated with little or no pain so long as the pulp is not invaded, the character or rapidity of the carious process seem- ingly making no difference. And yet some of these individuals would be classed as possessing the temperament known as nervous, while others would be classed as sanguine, DENTAL CARIES. - 163 bilious, and lymphatic. Does this lack of irritability to stimuli, applied to the dentinal fibrillse, lie in the fibrillge themselves or in the general ner- vous system of the individual 1 Or is there some difference in the char- acter of the micro-organisms which jjroduce the disease, or in the irritating quality of the acid produced by them ? These are the questions which the writer has often propounded to him- self, but has never been able to satisfactorily answer. In the third, or deep-seated, stage of caries, severe pain is often experi- enced from the entrance of irritating substances or their application to the diseased dentin. When decalcification of the dentin has progressed to a point that reaches the pulp, but not exposing it, irritating substances having gained access to the cavity of decay, often cause hypersemia of the pulp, and produce paroxysms of pain of a more or less severe character, lasting for a few minutes, or it may be for a much longer period. The irri- tation of the pulp may be so severe as to produce inflammation and death of the organ. The fourth, or complicated, stage is usually ushered in by pain of a severe and prolonged character, from the invasion of the pulp- chamber, which, permitting septic infection, causes inflammation and death of the pulp. It often happens, however, that the vitality of the pulj) has been de- stroyed by the irritating and septic conditions accompanying the deep- seated stage of the disease, and the pulp-chamber will be found to be oc- cupied by the remains of a gangrenous pulp ; or the exposure of the pulp may have resulted in a low grade of suppurative inflammation which has become chronic; or inflammation of a chronic type may have resulted in hypertrophy of the pulp, which has more or less completely filled the cavity of decay. Sensitiveness and pain, however, do not always accompany the progress of caries, even in the latter stages of the disease, and it is not uncommon with certain individuals to find the pulp-chamber invaded and the pulp in a gangrenous condition without pain being experienced at any period of the carious process. Diagnosis. — The diagnosis of caries can usually be made without much trouble, and yet in some cases it becomes a matter of considerable difficulty. The disease is to be sought for in those locations which expe- rience has taught the operator are the most vulnerable, and therefore the most likely to furnish evidences of tissue disintegration. These locations have already been indicated as found in the enamel in the natural fissures, sulci, and pits, u.pon the approximal, buccal, and labial surfaces, and not infrequently in cracks caused by traumatic injuries, and the expansion and contraction of the tissue incident to the great and rapid changes in tem- perature to which they are often subjected in going from a warm room to a cold outside atmosphere, often many degrees below zero ; or in immedi- ately following a mouthful of some hot fluid with another one of ice- water, a custom very common among Americans. These imperfections in the initial stage of the disease are frequently microscopic in size, but are, nevertheless, sufliciently large to give access to the organisms of caries. 164 OPERATIVE DENTISTRY, The approximal surfaces of the teeth are the locations which are most often the seat of caries, from the fact that the inter-appro ximal spaces give constant lodgement for alimentary debris^ and fluids are held by capillary attraction, thus favoring the processes of fermentation. The lingual, labial, and buccal surfaces are most free from the carious process, and in the order named, while their most vulnerable points are the developmental furrows and pits and the cervical margins at the free edge of the gums. Parreidt has ascertained that on an average one hundred carious teeth would be composed of twenty-six incisors and cuspids, twenty-eight bicus- pids, and forty-six molars. Of the incisors and cuspids, ninety-eight per cent., on an average, decay on the approximal surfaces, and only four per cent, on the incisive, lingual, and labial surfaces. The bicuspids decay most frequently upon the approximal surfaces, the percentage being ninety- two ; while the molars decay most often upon the morsal surfaces, the per- centage being seventy-two ; the approximal surfaces, twenty-eight ; the labial and lingual, two. He says, further, '' According to my observation, the first appearances of caries occur in sixty-four cases out of one hundred on the approximal surfaces of the teeth." These surfaces are often so close together that it is with extreme difficulty that the eye can detect the disease in its incipient stage without resorting to mechanical appliances for separation or the use of reflected artificial light. The most difficult cases to diagnosticate, however, are those which give no evidence to the eye of disintegration of the enamel, but are so far pro- gressed as to cause acute and severe pain. These most often begin in some tiny pit or fissure upon the morsal surface of the molars and bicuspids, or the buccal surfaces of the molars, in which the ]Drocess of decay has been so rapid and the point of entrance of the micro-organisms so small that there has been no change in the color of the affected tissue. The discovery of such cases calls for a high degree of skill and unlimited patience. Many such cases have been entirely overlooked by practitioners of con- summate skill and large experience, and diagnosticated as neuralgia or as imaginary pains. Too much care cannot be exercised in the examination and diagnosis of these cases, as a failure to find the cause often entails great suffering upon the patient and loss of reputation to the consultant. The means which are used in examinations of the mouth have been fully described in Chapter YI. , to which the reader is referred. Prognosis. — The prognosis of dental caries, if no therapeutical or sur- gical means are introduced for its arrest or control, is, as a rule, extremelj^ bad, for nearly every tooth so attacked will be sooner or later entirely destroyed. The prognosis for those teeth which are operated upon according to the most approved methods of conservation will depend in large measure upon the thoroughness with which these methods have been applied, and the care which is afterwards given by the patient to the hygienic conditions of the mouth. Eecurrence of the disease at the margins of the filling after a few years DENTAL CAEIES. 165 will invariably occur if the operation has been faulty, or the patient has been neglectful of the ordinary means of cleansing the teeth and preserving the mouth in a healthful condition. The disease in individual teeth may be arrested at any stage of its progress^ and recurrence prevented, provided the therapeutic measures above indicated are faithfully followed, but the tendency to the affection cannot be eradicated except by the removal in toto of the predisposing and exciting causes. Much, however, may be accomplished by the institution of certain pro- phylactic measures, which will be discussed in the following chapter. CHAPTEE X. TREATMENT OF CARIES. PROPHYLAXIS. Definition. — Prophylaxis (from the Greek ■Kp64>oXa^is, caution; tt^oo, be forehand ; (puXaffaw^ to guard, to prevent). The prevention of disease f preventive measures ; preventive medicines ; hygiene. The treatment of dental caries resolves itself into the application of those measures which aim at the prevention of the disease, — prophylaxis, — and those which are instituted to arrest the progress of the affection and remedy the defects and injuries which have been caused by it, — thera- peutics. Prophylactic treatment comprehends all of those measures which are insti- tuted for the purpose of removing the exciting causes of the disease, and, as far as possible^ rendering inoperative those causes which are predis- posing factors. The removal of the exciting causes of dental caries should, from the importance of the subject, receive our first and most earnest attention. As already indicated in a previous chapter, the science of dental surgery has not yet come up to the demands upon it in the prophylactic treatment of dental caries, and until such time as it does, the profession will not be fulfilling its highest obligations to its clientele. Cleanliness of the mouth and teeth is the greatest of all prophylactic measures lohich can be instituted against dental caries. This statement needs no verifi- cation, for it should be patent to every one whose observation and opera- tive experience have extended over even a limited period of time, as they must have noticed how exceedingly rare it is for caries to occur upon smooth surfaces of the teeth which are fully exposed to the friction of foods in mastication and the cleansing action of the tongue, lips, or cheeks, and the oral secretions. The prevention of caries, therefore, should aim at securing perfect cleanliness of the mouth, for this implies the destruction of the zymogenic micro-organisms of decay, and the removal of their acid products and all fermentable material, as well as the correction, so far as possible, of those constitutional conditions which lower the vitality and tend to vitiate the oral secretions. The value of perfect oral cleanliness is not generally understood by the public. Most peoj)le brush their teeth for purely cosmetic reasons, and not to prevent disease. It therefore becomes the duty of every dentist to so instruct his clients in the need of oral hygiene as a preventive measure against disease, and the means by which they may .secure this condition, that they will fully appreciate its value, and intelligently strive to carry out the instruction in all of its details. These measures should con- sist of : 166 TREATMENT OF CARIES. 167 1. Instruction to parents in the care of their children in relation to general measures of hygiene, — food, clothing, exercise, pure air, bathing, etc., — that the best possible development of the whole body, and conse- quently of the dental organs, may be secured. 2. In such a regular and systematic mechanical cleansing of the teeth and the mouth that the acid-producing bacteria and the fermentable sub- stances upon which they grow may be thoroughly removed or reduced to the minimum. 3. By j)rohibiting or so limiting the consumption of such foods and confections as furnish the material for acid formation that the chief source of lactic acid may be eliminated or greatly reduced. 4. In such a systematic and intelligent use of antiseptics that the zymogenic bacteria may be destroyed, or their number and action so limited as to render them practically harmless. Miller, in his experiments with the zymogenic bacteria of the mouth and the influence of certain prophylactic measures upon them, has ren- dered a service to humanity which is beyond calculation. The great value of mechanically cleansing the mouth with the brush, toothpick, floss-silk, etc., he demonstrated by taking ten cubic centi- metres of saliva from the mouth before cleansing it, and adding half a gramme of starch, and placing the mixture in the incubator. After cleansing the mouth an equal amount of saliva and starch were mixed, and, as before, placed in the incubator. The flrst mixture not only showed earlier signs of fermentation than the second, but also formed more acid in a given time. In later experiments he determined the amount of acid produced in two equal infections from the same individuals before and after a careful cleansing of the mouth and teeth, and found the amount of acid produced by the latter sometimes as low as one-fourth that of the former, while after the use of strong antiseptic mouth-washes the amount was reduced to nil. ''There is no known solution, alkaline or antiseptic, applicable in the human mouth, which will penetrate between the teeth, or to the bottom of fissures and cavities, — when these are filled with food, — in suflBcient quantity to have any appreciable effect. Therefore before all antiseptics or alkaline washes come the tooth-brush, toothpick, and floss-silk." Thorough mechanical cleansing of the teeth can only be accomplished by the use of all these means. The brush alone, even when used with the greatest intelligence, will not thoroughly remove the food debris from the inter-approximal spaces, and it becomes necessary to follow its use with the toothpick, and afterwards with waxed floss-silk drawn between the teeth, in order to free the proximate surfaces of all fermentable substances. To insure a perfect hygienic condition of the mouth this cleansing j)rocess should be repeated after every meal, and the mouth sterilized with an antiseptic solution after each cleansing, on retiring at night and upon rising in the morning. The importance of this statement cannot be over-estimated nor too strongly impressed upon those seeking the services of the dental specialist, for therein lies the salvation of the teeth. Too many people imagine that 168 OPERATIVE DENTISTRY. antiseptic mouth- washes are sufficient to correct the tendency to fermenta- tion, regardless of the fact that when food debris is retained between the teeth and in the sulci and fissures the antiseptics do not penetrate these substances, and therefore the action of the zymogeliic bacteria is only re- tarded upon the surfaces, while in the deeper portions it still goes on with unhindered rajiidity. Dentifrices of various composition are used as adj uncts to the mechani- cal action of the tooth-brush ; these are made in the form of powders, pastes, and soaj)S. Miller places no particular value on tooth-powder as a means of cleansing the teeth. He admits that the external surfaces, particularly of the front teeth, may be kept whiter by the use of tooth-powder, but thinks the centres of decay are more liable to become stopped up than to be cleansed by tooth-powder, particularly when they contain insoluble sub- stances. He would recommend tooth-soaj)S, in so far as they dissolve fatty sub- stances without attacking the teeth, and, furthermore, possibly make the penetration of the bristles of the tooth-brush into the centre of decay some- what more easy. He thinks the dentifrice should be made of neutral soap and have a neutral or slightly alkaline reaction, and finally says, '^ Under all conditions, however, the chief thing is the thorough mechanical cleansing of the teeth." Tomes says, "In many respects tooth-soaj)S are to be preferred to powders." The writer, however, has never been able to appreciate the advantages of the tooth-soaps over tooth-powders or tooth-pastes, for there are few mouths in which the teeth can be kej)t bright and clean without the polishing effect of some form of tooth-powder containing calcium carbonate or magnesium carbonate. All good tooth-powders and pastes should contain a sufficient amount of the best castile soap to gain the advantage of its dissolving action upon fatty substances. The following formulae will be found useful. Tooth-powder. Tooth-paste. R Precipitated chalk g viii ; R Precipitated chalk g viii ; Pulv. orris root 5 iv ; Pul v. orris root ,? iv ; Pulv. cinchona bark ^ iv ; Pulv. cinchona bark g i v ; Pulv. cinnamon ^ v ; Pulv. castile soap 5 ii ; Pulv. castile soap 5 ii ; Bicarbonate of soda 5 i ; Pulv. white sugar 5 iv ; Oil of gaultheria f 3 ss ; Oil of lemon gtt. xx ; Glycerol, q. s. to make a thick paste. Oil of rose gtt. ii. Mix, pulverize, and sift the dry ingredients Mix, pulverize, and sift through a fine before adding the oil of gaultheria hair sieve. and the glycerol. It is not necessary to give more than one or two formulae for dentifrices, as a large variety of good powders, pastes, and' soaps have been placed upon the market by the dental dealers, most of which are entirely reli- able, and the dentist may place them in the hands of his clients with con- fidence that they, are what they are represented to be. TEEATMENT OF CARIES. 169 Miller, in his exxDeriments with regard to the effects of various anti- septics upon the zymogenic function of the mouth-bacteria, found great difSiculty in selecting substances to which serious objections could not be raised, either from their injurious effects u^Don the teeth or the mucous mem- brane, their general toxic effects, or from their disagreeable taste or smell. The following substances, in solutions admissible for use in the mouth, were tested by him as to the time necessary to devitalize bacteria. Several of them were found to accomplish this result inside of one minute. Antiseptic- Salicylic acid* Benzoic acid* Listerine Salicj'Iic acid Bichloride of mercury Benzoic acid Borobenzoic acid Thymol Bichloride of mercury Peroxide of hydrogen Carbolic acid Oil of peppermint in agreeable strength. Permanganate of potash Boric acid Oil of wintergreen Tincture of cinchona Lime-water Concentration. 1 to 1 to 100 100 1 to 200 1 to 2500 1 to 200 1 to 175 1 to 1500 1 to 5000 10 per cent. 1 to 100 1 to 4000 1 to 50 Ito 18 Time necessary for devitalization. I minute. |- minute. 1 to J minute. J minute. 2 to I minute. 1 to 2 minutes. 1 to 2 minutes. 2 to 4 minutes. 2 to 5 minutes. 10 to 15 minutes. 10 to 15 minutes. 5 to 10 minutes. More than 15 minutes. More than 15 minutes. More tlTian 15 minutes. More than 15 minutes. No action. It will appear that only a very few of these substances are really ser- viceable for the purpose of disinfecting the mouth, for the reason that the time necessary to destroy the vitality of the bacteria is too long. Solutions which will not sterilize the oral cavity in from one to two minutes would possess little value as antiseptic mouth-washes, for usually such solutions do not remain in the mouth for more than a few seconds, or at most for a minute. According to Miller, ' ^ The bichloride of mercury is the most active, not only because it has the highest antiseptic power, but because its action continues for a longer time." Lister, who used it very extensively in his surgical practice at one time, has gone back to carbolic acid, for the reason that a five to ten per cent, solution penetrates the tissues to a greater depth than a 1 to 500 solution of bichloride of mercury. Strong bichloride solutions coagulate the albumin upon the surface, and thus form a barrier against the pene- trating effect of the drug. Listerine was found by Miller to be a very efficacious preparation for sterilizing the mouth. It produced devitalization of mouth- bacteria in from one-fourth to one-half a minute. It should be applied to the tooth- brush or diluted one-half as a mouth-wash. Salicylic and benzoic acids may be apphed in this concentration only on the brush. 170 OPEEATIVE DENTISTEY. Pasteurine, borolyptol, thymozone, and other similar preparations whicli are combinations of benzoic acid, thymol, formalin, etc., are efficacious in sterilizing the mouth, have a favorable tonic action upon the soft tissues, and reduce inflammation. Miller found that the oil of wintergreen and other similar aromatic substances, which usually form an important constituent of mouth- washes, have, in an adaptable concentration for use in the mouth, very little anti- septic action. He, however, excepts oil of peppermint from this category. Black extols the antiseptic qualities of oil of cassia, oil of cinnamon, and oil of cloves, and thinks they have a much higher antiseptic power than oil of peppermint. Koch, on the other hand, found oil of peppermint to have an anti- septic action nearly seven times as strong as oil of cloves. Miller thinks this difference between these astute observers may be accounted for in the difference of the bacteria experimented upon. Thiersch's antiseptic solution the writer has found to be a most valuable sterilizing mouth-wash. It is slightly bitter to the taste, but this may be disguised by the addition of a few drops of oil of cassia, oil of pepper- mint, or oil of wintergreen. The formula is as follows : Salicylic acid, four parts ; boric acid, twelve parts ; water, one thousand parts. Flavor to suit the taste. It may be used ad libitum. The most effective method of using antiseptic mouth-lotions is that suggested by Ottolengui, to force the solution between the teeth and over the surfaces by means of an atomizer. CHAPTEE XL TREATMENT OF CARIES (CONTINUED). MEDICATION. EXCISION. Definition. — Therapeutics (from the Greek eepaizeoruii^ curative). That branch of medical science which considers the application of reme- dies as a means of cure. The therapeutic treatment of dental caries consists in the application of certain surgical principles and mechanical procedures which are adapted to the peculiar nature and causation of the disease, the character of the tissue affected, the extent and the rapidity of the progress of the affection, its complications, the environment, and the liability of the disease to re- currence. The surgical procedures which are applicable to the cure of dental caries are Medication, Excision, and Obturation or Filling. MEDICATION. Treatment by medication consists of impregnating the softened sur- face of enamel or dentin with nitrate of silver or some other salt which will destroy the bacteria which have penetrated these tissues, and so change the character of the impregnated tissues that they no longer offer a favor- able field for the growth and development of the lactic-acid-producing fungi. The idea of arresting dental caries by the application of the nitrate of silver was presented more than fifty years ago. It, however, never came into general use except in the treatment of superficial caries in the pos- terior part of the mouth. The great objection which has been raised against its employment is the fact that it stains the eroded enamel and the exposed dentin jet-black, thus giving a very unsightly appearance to a tooth so treated. If the treatment, however, has been successful, the black stain gradually disappears, leaving a polished mahogany-brown surface, which is immune to caries. Stebbins (1891) revived interest in this method of treatment by advo- cating its use for the arrest of caries in the temporary teeth. The black- ening of the decayed surface in these cases is not so objectionable as in the permanent teeth, while it often renders the preservation of the deciduous teeth a much easier task than by the more difficult, laborious, and painful operation of inserting a filling. Stebbins advocated the application of a solution of silver nitrate to the carious cavity by means of a small pointed stick inserted in a socket in- strument or porte- carrier made for the purpose. He found that many cases needed no further treatment, as the carious process was completely arrested, while in others, after a few months, a 171 172 OPERATIVE DENTISTRY. second application was necessary. In many cases he thought it advisable to fill the cavities with gutta-x:>ercha after the application of the silver nitrate. Peirce recommends that application be made by means of pieces of blotting-paj^er of suitable size, saturated in a forty per cent, solution of the drug, and kept ready for use. Kirk objects to the use of blotting-paper or cotton as a means of apply- ing the solution, for the reason that ^'the contact of silver nitrate with vegetable fibre of any sort involves not only a destruction of the fibre, but also of the silver nitrate, so that the preparation in a short time loses its desirable qnalities." He advises instead the use of asbestos felt which has been heated before the blow-pipe to eliminate all vegetable matter previous to saturation with the solution. Holmes suggests, in the treatment of j)roximal cavities, that the walls be "cut away to a V shape, and with a piece of gutta-percha softened by heat, of the proper size of the space, bring the surface to come in contact with the diseased part of the teeth in contact with the powdered crystals of silver nitrate, and carry it into place in the tooth or teeth prepared for its reception, packing it firmly, and leaving it there to be worn away by use in mastication. "When that takes ijlace the surface of the teeth will be found black and hard, with no sensitiveness to the touch or to changes in temperature, and they will remain so indefinitely. In case the child is so timid as to ])revent this course, dry the cavity, take out as much softened dentin as the patient will permit, carry the crystals on softened gutta-percha into the cavity, and i)ack it there, leaving it until such time as desirable to make a more thorough operation." Goddard deprecates the practice of making Y-shaped separations in these cases, and believes it better to open proximal cavities from the morsal surface, "as the full diameter of the teeth is necessary to preserve the fulness of the arch." The writer maintains the same opinion, but would add another reason, — viz., that the iJ reservation, when j)ossible, of the full size of the morsal surface of the teeth is important from the fact that if they are cut away the power of thoroughly grinding the food is by that much curtailed, and the child forms the habit of swallowing its food before it is properly masticated. EXCISION. In the operation of excision the diseased part is cut away with files, or with disks revolved by the dental engine, and the surface thoroughly polished. This operation is only admissible in the superficial stage of the disease. The advisability of the operation has been seriously questioned, however, by some of the best operators in the profession ; and in the light of the recent discoveries made by "Williams in the modus operandi of enamel decay it would seem that the operation can be of very little benefit as a therapeutic measure. It may possibly retard the progress of the disease for a time by removing the roughened surface of the enamel, and thus making it a somewhat less favorable surface for the attachment of the zymogenic fungi, but as a permanent cure it is not to be relied upon, TREATMENT OF CARTES. 173 althoiigli every operator of experience has, no doubt, seen cases in which the operation has proved permanently curative. Many of the older operators, fifty years ago, practised the operation very extensively, and they were often quite successful in arresting the progress of the disease, but they did it at a great sacrifice of tooth-struc- ture. Approximal cavities in bicuspids and molars were often treated in this way, the method being to cut large Y-shaped spaces, the apex of the V at the cervices of the teeth, the base being so broad that the surfaces thus formed would be kept clean by the friction of mastication. Arthur at a later period (1871) introduced and extensively practised a modified form of the operation as a prophylactic as well as a curative method. He argued that the great majority of individuals suffered from proxi- mate caries of their teeth ; also that it was j)ossible for the dentist by in- telligent observation to determine in advance those cases in which caries would occur. Observation had also taught that when the teeth were so arranged naturally that they were well separated from each other, im- munity from caries was the general rule ; further, that the separation by filing, practised by the older dentists, often arrested the disease and gave immunity to such surfaces from further destruction ; that accidental in- juries to the teeth which exposed the dentin, when in locations that were kept clean by the friction of mastication, and the practice of many abo- riginal races of filing their teeth for various purposes without injury to the dentin, led him to believe that the enamel might be removed without harm to the teeth, provided the surfaces and spaces thus made were of such shape that they could be readily cleansed. The friction of mastication and ordinary care on the part of the patient, he believed, would be suffi- cient to prevent the occurrence of the dis- ease. The method which he advised and practised was to separate the bicuspids and molars by means of thin corundum disks (Fig. 295), but as far as possible retaining the natural contour of the proximate surfaces. The six anterior teeth were separated by the same means, but in this case the separation consisted in forming Y-shaped spaces upon the lingual surfaces, the apex of the Y being directed towards the lip and the base towards the tongue. For a time this practice was followed by a considerable number of practitioners, but it gradually fell into disrei^ute from the fact that the claims of its advocate could not be realized by those who adopted it, except in a few isolated cases. Fig. 295. Corundum disks. CHAPTEE XII. TREATMENT OF CARIES (CONTINUED). The separation of contiguous or adjoining teeth, the proximate sur- faces of which may be the seat of caries, is an important and an essential procedure, preliminary to the operation of removing diseased tissue and restoring the tooth to its original form by the introduction of some suit- able filling-material. The enlarging of the interproximate space for a brief period is not only necessary, that a direct view of the cavity may be obtained, and facilitate the operation of cavity i)reparation, but that it may give oppor- tunity for restoring the original contour of the teeth with the filling material, so that when they return to their normal positions their relations to each other will be the same as before they were attacked by the carious process. Separation by filing is to be deprecated, and in these days it is rarely practised, as the restoration of contour is not possible by this method of separation. The resulting consequences from failure to restore the normal contour and mutual relationship of such teeth, particularly the bicuspids and molars, is often very serious. When permanent separations are made, either by filing or failure to restore the contour so that the approximal sur- faces do not '^ knuckle up" to each other, food is driven iuto the inter- proximate space, to the great annoyance of the patient and often painful and serious injury to the gum, inducing pericementitis, recession of the gum, and sometimes loss of the affected tooth. In dealing with the anterior teeth the restoration of contour is also important from the aesthetic stand-point. Teeth which have been perma- nently separated by filing x^resent mutilations which in themselves con- stitute a deformity, while they often move out of their normal position by tilting towards each other, or assuming other positions out of harmony with the natural arrangement of the arch. The separation of the teeth is a procedure which calls-|Mj considerable care to avoid injury to the pericemental membrane a»F gum and to render the process as nearly painless as possible. There is considerable difference in individuals as to the amount of soreness and pain produced by separating the teeth. In children and young people the necessary space is gained much more quickly and with less irritation than when the alveolar walls have become firm and compact, or when the arch is full and the teeth are in close proximity. In the former the bone yields readily and permits an expansion of the arch, while in the latter the resistance to force is much greater and the process of expansion considerably slower. 174 TREATMENT OF CARIES. 175 A certain amount of space is always gained, even in a full arch, by the closing of the slight spaces which often exist between the teeth. It is therefore important that the force applied and the materials or aiDpliances used should be adapted to the conditions presented in each individual case. Constant and sustained pressure, if the force used is not too great, will separate the teeth more quickly and with less irritation than if applied intermittingly. With such precautions as would be suggested by good judgment no harm can come from the process, even when the tissues are irritable or the structures are of the firmest character. There is no diffi- culty in obtaining sufficient space for any operation if proper care is ex- ercised and the force is steadily and mildly applied. Methods of Separation. — Separations may be obtained by the em- ployment of various means, the selection of which should be governed by the conditions and requirements of the case in hand, — viz., the amount of space required, the time in which it must be accomplished, the firmness and irritability of the structures, and the location of the teeth to be sepa- rated. Two methods are employed to gain space by wedging, one termed immediate or direct, the other gradual or indirect. Immediate or direct wedging is most applicable to the anterior teeth, where usually only a limited amount of space is required. Its greatest advantage, however, lies in its use as a method of obtaining space for the examination of the proximate surfaces, and to permit the introduction of polishing strips, for the removal of superficial softening of the enamel, stains and discolorations, and for the purpose of repolishing fillings. Immediate separation may be accomplished by forcing properly shaped wooden wedges between the teeth, either by steady pressure or by driving with the mallet. The wedges should be made of hard, close-grained wood, orange- wood being the best. The wedges should be inserted between the teeth, one near the morsal edge, the other at the cervix, care being taken not to impinge upon the gum in such a manner as to bruise or otherwise injure it. These are then alternately forced farther and farther until the desired space is obtained. The angular form of the interproximate space sometimes makes it im- possible to use a wooden wedge, as the wedge travels towards the gum as soon as force is applied, instead of producing lateral pressure upon the approximal surfaces and insuring fixation of the teeth. Mechanical Separation. — Various mechanical appliances have been invented for the immediate separation of the teeth. The best for separating the anterior teeth is, no doubt, the one invented by Woodward, while those best adapted for gaining space between the bicuspids and molars are the Parr and the Perry forms (Figs. 296^ and 297). Separations made by the aid of these instruments for the examination of the approximal surfaces or to gain space for operations are far less painful than those obtained by driving the wooden wedge. They are also valuable for increasing the space gained by other methods, and for fixing the teeth which have been separated by the gradual method, and in which there still remains a little pericemental irritation and soreness. When 176 OPERATIVE DENTISTRY. the patient is pressed for time it often becomes necessary to operate before the irritation lias entirely subsided, but without some such support as this it would be impossible to operate, on account of the discomfort which would be caused to the patient, and which would be increased at every stroke of the mallet. Mechanical separators, however, have the disadvantage that they cannot be used in all locations, even if one possess a half-dozen or more different Fig. 296. Parr separator. Perry separator. forms, while with the Perry instrument there is a constant tendency for it to slip towards the gums. This can, nevertheless, be overcome by placing beneath the bows small pieces of gutta-percha or india-rubber. Parr's instrument is more universal, but it is decidedlj^ more clumsy. Gradual or indirect wedging may be accomplished by the introduction between the teeth of thin wooden tvedges, which should be changed to thicker ones each day, depending upon the swelling of the fibres under moisture to produce the sej)aration. Linen tape, either waxed or unwaxed, is an admirable material with which to sex)arate the teeth. Waxed tape will j)ass more readily between teeth that stand close together than will the unwaxed, but it does not move the teeth so quickly as the unwaxed, the wax preventing the rapid absorption of moisture and swelling of the fibres. It becomes necessary sometimes, however, to begin the separation by the immediate method, — either with a wedge of wood or the separator, — as it is impossible to get anything between the teeth without the application of considerable force. As soon as sufficient space is gained, the tape may be inserted and the separating appliance removed. The tape should be removed each day and a thicker one inserted, until such time as the required space is obtained, when gutta-percha may be packed be- tween the teeth and allowed to remain until all soreness has disappeared. In fact, this or similar means of retaining the teeth in their separated position should always follow the removal of the material used for gradu- ally separating the teeth, as it is always best to wait for soreness to dis- appear before beginning the operation of filling. Pledgets of cotton may also be used as a means of separating the teeth, especially in the posterior teeth when the cavity has been broken through the morsal surface. The pledgets should be ]3acked as tightly as possible when the cavity is not so deep as to involve a vital pulp. The cotton may then be saturated with sandarach varnish to bind the fibres together. TREATMENT OF CARIES. 177 The front teeth may be separated with the same material by twisting it into a strand, drawing this between the teeth, and cutting the ends short. The cotton will act more rapidly, however, without the sandarach varnish, as this retards the absorption of water, and consequently the swelling of the fibres is more gradual. India-rubber — caoutchouc — in strij)S of various widths is i)erhai3S, on ac- count of its effectiveness, more frequently used than any other means of producing gradual separation. When a strip of india-rubber is drawn between two teeth the middle portion is pressed to great thinness, the ends acting as two opposing wedges, the elasticity or resilience of the material constantly drawing the ends or wedges together until a space is obtained equal to the thickness of the strip. Great caution, however, should be exercised in using this material, as its power is very great, and serious pericemental inflammation may be induced by the use of strips which are too thick. Separations of almost any desired width may be obtained with this material, with little or no irritation, if only the strips used are thin enough and are changed every day. Red base-plate gutta-percha has been recommended by Bonwill as a de- sirable material with which to gradually separate the teeth. It should be packed firmly into the open cavities and existing space between the teeth, depending u^Don the force of mastication to produce expansion by driving the material towards the gum. This material is also valuable for exposing the cervical margins of the cavities which are covered by overlapping gum-tissue, by packing it into the cavity and interproximate space. It is much better than cotton for this purpose, as it does not absorb septic material. EXCLUSION OF MOISTURE. The exclusion of moisture during all operations upon the teeth is of the greatest importance. The presence of the oral secretions is often a serious obstacle to the performance of many operations, and when the flow is ex- cessive it becomes a matter of considerable annoyance to the patient. All operations upon the teeth are more successfully performed by the exclusion of inoisture than when the mouth is flooded with its secretions ; but for the introduction of gold as a filling-material, and in the treatment of de- vitalized teeth, it becomes an absolute necessity. In the earlier days of modern dentistry the question of the exclusion of moisture during a long and tedious operation with cohesive gold caused the dentist many anxious thoughts, and added not a little to the nervous strain incident to his professional life ; a strain which the younger mem- bers of the profession can hardly realize or appreciate, since they are furnished with a material — the rubber dam — which removes entirely all anxiety upon the part of the operator that his operation may be com- pletely ruined by the entrance of moisture and his labor come to naught. Various methods and appliances have been introduced for the purpose of securing and maintaining dryness in the field of oiDeration, including 12 178 OPERATIVE DENTISTRY. the napkin, bibulous paper, cotton pads, gauze, saliva ejectors, and tlie rubber dam. Napkins. — The use of napkins as a means of excluding moisture is the oldest, and was for many years the only one, with which the older practi- tioners daily fought the battle of maintaining a dry field for their opera- tions. It is still a valuable method, and is often resorted to in those cases in which the rubber dam cannot be employed, as, for instance, in the treat- ment of molars which are only partially erupted, or in those persons to whom the dam is so disagreeable or nauseating that they will not permit its use. Napkins for this purpose should be made of the best diaper or bird's- eye linen of various sizes, six inches, nine inches, and twelve inches square being the most useful sizes. The smallest ones folded in pads the full length of the napkin are admirable for use in the lower part of the mouth, and are applied by placing one end of it opposite the incisor teeth, be- tween the tongue and the lingual surfaces of the teeth, carrying the middle of the napkin to the angle of the jaw, folding it upon itself, and laying the other half between the cheek and the buccal surfaces of the teeth, and holding it in place with the thumb and index-finger of the left hand. If the tongue is raised before the napkin is applied upon the lin- FiG. 298. Fig. 299. Bicuspid napkin clamp. Molar napkin clamp. gual side of the teeth, the tongue will hold this end of the napkin in place, and at the same time press it down upon the orifices of the sublingual and submaxillary glands. A better means of holding the napkin in posi- tion is to apply the Ivory napkin clamp. (See Figs. 298 and 299). The larger napkins are folded by taking hold of one corner with the thumb and index-finger of the left hand and the lateral corners rolled or folded in. It is applied, for instance, to the upper left side by passing the corner held by the left thumb and finger under the lip at the left oral commissure, holding it there with the index-finger of the left hand, and with the index-finger of the right hand or a pair of dressing forceps carry the thicker part of the napkin backward to the tuberosity of the jaw ; then folding it upon itself, it is brought forward along the lingual surfaces of the teeth and maintained in its position with the left index -finger. The free end of the napkin is then spread out so as to cover the lower lip. The procedure for the right side is the same, with the exception that the hands are reversed. Bibulous paper, prepared gauze, and cotton pads are now used by some TREATMENT OF CARTES. 179 operators to the exclusion of napkins. Their application is similar to that of napkins folded into pads. The moisture which appears around the necks of teeth, coming from the glands at the margin of the gums, is often quite troublesome when only the napkin or similar means are used to exclude the moisture. This may be controlled by packing small pieces of bibulous paper between the teeth at the cervix. Saliva Ejectors. — These instruments are exceedingly useful in con- junction with napkiuSj bibulous paper, etc., or with the rubber dam, for removing the secretions that accumulate during the operation. In many operations the necessary position of the jaws is such as to make it impos- sible for the patient to swallow, hence the accumulation of saliva is often very troublesome to both the patient and the operator, especially so when the secretions are normally excessive, or are greatly increased by the stimulation of operative procedures. These instruments act upon the principle of the siphon, and are made for attachment to the water-supply and used in connection with the fountain cuspidors. Rubber Dam. — Barnum conferred a great boon upon suffering humanity and greatly lightened the labors of the dentist by his invention of apply^ ing sheet-rubber or rubber dam as a means of excluding moisture from the field of dental operations, thus making it possible to save many teeth which before were condemned to the forceps. It has universal applica- tion in all parts of the mouth wherever a tooth or root has sufficiently emerged from the gum for the dam to be passed over it. It is of greatest value, however, in the preparation and filling of proximal cavities where the disease has extended beneath the gum, and in which the exclusion of the secretions and of blood is a difficult matter with any other means at our command. For the exclusion of moisture and septic secretions, and the protection of the soft tissues from medica- ments in the treatment of devitalized teeth, alveolar abscesses, etc., it is indispensable. Rubber dam is made in three thicknesses, known as thin, medium, and thick, and usually sold in strips varying in width from five to seven inches. The preference for general use lies with the medium thickness, although it is well to have all three thicknesses on hand. The quality of the rub- ber is a matter of first importance ; it should be strong, elastic, extensible, and free from odor. Exposure to the atmosphere and the high tempera- tures of summer weather cause deterioration in these qualities and soon render it worthless. To protect it as much as possible from these deterio- rating influences it is usually sealed in tin cans or boxed. It should be cut for use into squares and triangular i)ieces, the squares from five to seven inches, the triangular pieces being made by folding the squares corner- wise and dividing them. A form of rubber dam has lately been introduced which is coated with a metallic aluminum powder, which gives it a very light appearance and adds greatly to its usefulness by making it luminous. The aj)plication of the rubber dam is to the student in his first attempt to adjust it a somewhat difficult procedure ; to the older practitioner who has become expert by long practice it is usually a simple matter, requiring 180 OPERATIVE DENTISTRY. but a moment of time ; and yet occasionally a case will present in which its application will require all his ingenuity and patience. In adjusting the dam to a tooth with a simple cavity upon the morsal surface, a hole should be pinched or cut at such a location as will permit the dam to lie smoothly over the mouth after its adjustment to its position. The dam may be adjusted by grasping the two upper corners with the thumb and index-finger of both hands, and with the middle finger of each hand placed on opposite sides of the hole through which the tooth is to pass, the rubber is put on the stretch. This enlarges the hole in the rubber, and it is forced over the tooth by passing first one edge and then the other of the opening between the mesial and distal proximal spaces, and carrying it well up to the cervix. Fig. 300 shows the rubber dam in position upon the upper incisor teeth, the upper corners of the dam being Fig. 300. Fig. 301. Rubber dam applied. Rubber-dam holder. secured with a rubber-dam holder (Fig. 301) Various other forms of holders are also for sale by the dealers, and the operator may suit himself with almost any desired form. The rubber dam may be held smooth by attaching weights to the lower corners. If two or more teeth are to be isolated, it then becomes necessary to punch the same number of holes in the dam, so locating them that when the dam is placed in position the straits between the holes will be just a trifle wider than the spaces between the teeth ; the edges of the dam around the cervices of the teeth should then be turned under, using the point of any straight-pointed instrument of suitable size. The dam thus grasping the cervix of the tooth acts as a valve, and effectually excludes all moisture from the teeth so enclosed. To secure the dam in position, a ligature may be passed around each tooth and tied with the surgeon's knot, or clamps of various forms (Fig. 302) are used alone for the same purpose, TREATMENT OF CARIES. 181 or in conjunction with the ligatures. Properly constructed clamps are so shaped that they materially assist in holding the dam away from the crown of the tooth, thus causing less obstruction to the entrance of light Fig. 302. Ivory's claraps. and giving a better view of the field of operation. The Ivory clamps possess these very desirable features to a greater extent than any others at present known to the writer. Fig. 303. The Ottolengui clamp applied. The Ottolengui clamp (Fig. 303) also possesses many of the desirable features. Fig. 304. Dr. How's cervix screw clamp. The How cervix screw clamp (Fig. 304) is an admirable instrument for securing the dam and exposing the cervical margin in cervical cavities. Its application is shown in the illustration. 182 OPERATIVE DENTISTRY. Specially constriictecl forceps are necessary in the adj ustment of all forms of spring clamps like those shown in the preceding illustrations. Fig. 305 shows a method of adjusting the clamp and the rubber dam at the same time. The clamp in the illustration is known as the Elliot molar clamp, and is a favorite appliance with many operators. Fig. 305. Elliot's clamp and forceps. When the teeth are very close together and the alveolar walls are very firm, it is sometimes a difficult matter to pass the dam between the teeth without some special preparation of the contiguous surfaces. The rubber- dam applier, shown in Fig. 306, duplicates the fingers and materially Fig. 306. Rubber-dam applier assists in forcing the dam between the teeth. In all such cases the passage of the dam may be facilitated by first lubricating the surfaces by passing floss-silk between them which has been charged with vaseline, cosmoline, or toilet soap. The holes in the dam may be made either with the punch (Fig. 307), the scissors, or by stretching the dam over .the end of a small, round. Fig. 307. Ainsworth's rubber-dam punch. tapering instrument, — the reverse end of a mallet-plugger will answer the purpose, — and nicking the rubber near the point with a sharp knife ; the result is a perfectly round hole. Any desired size may thus be obtained ; TREATMENT OF CARIES. 183 the lower down upon the instrument the nick is made the larger the hole ; the tighter the dam is drawn the smaller the hole will be. The writer has used this method many years, to the exclusion of all others, and with perfect satisfaction. Fig. 308 shows the relative size of holes adaj^ted to (1) incisors and cuspids, (2) bicuspids, (3) molars. The depressed rubber dam (Fig. 309) Fig. SOS. Fig. 309. Depressed nibber dam. and the Denham coffer-dam shield (Fig. 310) are often found useful in operations for children and in preliminary treatments, or when remedies are to be used which it is desirable should not come in contact with the surrounding tissues of the mouth. Fig. 311 shows the Denham coffer-dam shield adjusted and secured with a clamp. A small mirror (Fig. 312) may be inserted in the depressed rubber dam for the purpose of greater illumination. Fig. 310. Fig. 311. 'i ^ s\ Denham coffer-dam shield. Fig. -312. Mirror. Denham coffer-dam shield adjusted. Nausea and other unpleasant symptoms are often occasioned by the contact of the rubber dam with the tongue and palate, and from the un- pleasant odor. The nausea may be relieved by spraying the mouth and throat with a two per cent, solution of cocaine in water, while the un- pleasant odor may be overcome by dipping the dam in rose-water or other toilet- water. Jack recommends painting the parts with tincture of cam- phor, while the nervous conditions which sometimes appear on adjusting the dam and covering the mouth may be overcome by requesting "the patient to breathe freely through the nose. CHAPTEE XII I. HYPERSENSITIVE DENTIN. Dentin is a fibro-calcareous structure, tubular in character, the tubuli passing from the i)ulp-chamber to the periphery of the dentin, branching in their course, and terminating in minute tubules, which unite to form an intricate plexus. These tubuli are each of them traversed by a minute fibril or filament, which is generally thought to be a prolongation of an odontoblastic cell, and that through these fibrils sensation is conveyed to the dental xDulp. There is some evidence, however, as already pointed out in Chapter III., that a portion of the tubuli are occupied by certain fibres, which appear to be prolongations of the nerve-filaments of the pulp, or that the nerve- filaments of the pulp enter the odontoblasts, and thus furnish the necessary elements which fit the fibrillse to carry sensation. It has never been demonstrated, however, that the fibrillte of the dentin were composed of nerve-tissue, and yet there can hardly be a doubt that such is their composition, for they perform the functions and x^resent all the phenomena of nerve-tissue under stimulation and under irritation. Dentin in its normal state is only slightly sensitive, but when subjected to irritation from external agencies it may become most excruciatingly %j9ersensitive. The degree of hypersensitiveness will dei^end upon the character of the irritant, the point of attack, its duration, the condition of the oral secretions, the character of the structural development of the teeth, the age, and the physical condition of the patient. Irritation from caries is the most common cause of hypersensitive dentin, the degree of abnormal sensitiveness dex^ending largely ux)on the char- acter of the carious x^rocess. In the white or rapid form of caries the hypersensitive condition is usually the most exalted. In the brown or less rapid form the sensitiveness is much less, while in the NacJc or slow form it is but little above that of normal dentin. The most sensitive part of a carious tooth is just beneath the protecting enamel or cementum, on the periphery of the dentin at the terminal ends of the fibrillse, just as the most sensitive part of the external surface of the body lies immediately beneath the horny layer of the cutis at the termina- tions or end organs of the nerves. It therefore becomes evident that caries in the superficial stage will x^resent the highest degree of hyxDersensitive- uess to be found in each of the three forms of caries. In other resx^ects the zone of greatest sensitiveness is directly beneath the softened portion of dentin, the sensitiveness becoming less and less as the sound tissue is apx)roached. Another cause of hyx^ersensitive dentin is irritation from attrition or mechanical abrasion. This cause, however, ox^erates so slowly that certain 184 HYPERSENSITIVE DENTIN. 185 changes may take place in the dentin within the tubuli by the deposition of calcific deposits^ — ehurnation, — which after a time diminishes or entirely destroys their capacity to convey sensation. The same process of eburna- tion sometimes takes place in chemical abrasion and denudation, thereby lessening and sometimes entirely obliterating sensation. Exposure of the cementum from recession of the gums is another very common cause of hypersensitive dentin, but here again nature is prone to mitigate the conditions by the same calcific changes in the dentinal tubuli. But caries often supervenes in these cases from lack of attention upon the part of the patient, who, because of the pain induced by the use of the brush, fails to keep these surfaces properly clean. There is also very often the added influence of acid mucous or salivary secretions, which by their irritating effect tend to augment the hypersensitive condition, while the reverse is true when the oral secretions are alkaline or neutral. Excessive sensibility of the teeth is often an accomj)animent of the catamenia, of dyspepsia, neuralgia, pregnancy, pulmonary tuberculosis, especially in its later stages, typhoid fever, acute rheumatism, and the convalescent stage of fevers in general. The condition under these circum- stances is due to the changed or vitiated character of the oral secretions, which have almost invariably a strongly acid reaction. Imperfect calcification of the teeth is another factor in the etiology of hypersensitive dentin. The teeth of children and of rapidly growing young people are, as a rule, much more sensitive than those of adults. This is thought to be due to the fact that the teeth during childhood and youth are still undergoing changes of development, and that they are not all fully formed, in the sense of being perfectly calcified, until adult age ; but that as each group of teeth are perfected they become less susceptible to external irritants, and consequently less sensitive. Females, however, as a general rule, are more often sufferers from hypersensitive dentin thp^n are males. Nervous irritahility is greater in some persons than in others, females usually possessing a larger share than males, and this in a measure accounts for the intense suffering which some of these individuals endure from hypersensitive dentin. This exalted irritability of the nervous system in some instances is only a passing condition which has developed as the result of illness, mental or physical shock, overwork of mind or body, over-indulgence in social pleasures, or of debaucherj^ ; while in other in- stances it is an established condition or dyscrasia peculiar to the indi- vidual ; or it may be a family peculiarity which has been transmitted as an inheritance. In any event the suffering is so great in some of these cases of hypersensitive dentin as to call for the greatest sympathy, considera- tion, and forbearance upon the part of the operator during the preparation of the cavity. The dentist who cannot rise to such an occasion, and by tenderness and sympathy endeavor to carry the patient through the trying moments of the ordeal without losing his patience, should change his occupation, as he lacks or has lost the most important qualification for a successful dental practitioner. 186 OPERATIVE DENTISTRY. TREATMENT OF HYPERSENSITIVE DENTIN. The treatment of hypersensitive dentin is one of the most perj)lexing problems with which the dentist has to deal, and consequently the reme- dies which have been suggested and introduced from time to time for ob- tunding the sensation of dentin have been legion. Each new remedy has generally been extolled as a specific ; but each of them, after a few trials, has been laid aside, with the hopes that were from the beginning doomed to disappointment. Specific medication succeeds no better in the treat- ment of dental diseases than it does in general medicine. Certain remedies which may cure in one case often prove only an aggravation in another, and remedy after remedy may be tried with no appreciable beneficial effect ; while, upon the other hand, certain drugs have been found which will upon their application to the dentin positively destroy its sensation, but will also destroy or jeoj)ardize the vitality of the pulp. The treatment of hypersensitive dentin is therefore limited to those remedies and procedures which will temporarily relieve or mitigate the suffering incident to the preparation of cavities, or to give permanent relief in the various other forms of irritation to which the vital dental tissues are subjected. Treatment of Moderate Hypersensitiveness. — In the treatment of moderate hypersensitiveness due to caries the excavation of the cavity should be approached in a manner to engender confidence upon the part of the patient that the operator will endeavor to perform his task with the least possible pain and in the most expeditious manner that the nature of the case will permit, assuring the patient that, if the pain is unbearable, palliative means shall be employed for its relief. With such assurances, accompanied with a calm, cheerful, and sympathetic manner upon the part of the operator, the courage of the patient can usually be stimulated to such a degree that the operation may be completed without resort to obtunding agents. By a display of harshness in the methods of operation, or an exhibition of irritability of temper, or an unsympathetic mood upon the part of the operator, apprehension, dread, and nervous excitement are increased, and the difficulties of controlling the patient by just that much augmented. It is often advisable in dealing with nervous individuals, either adults or children, to select for the first operation something that will cause little or no pain, that they may become acquainted with the various surround- ings and procedures incident to dental operations. This will relieve their dread and apprehension for the time, and thus make it possible to advance by degrees from the simpler and comparatively i)ainless operations to the more complicated and severer ones. In excavating the simpler cases of moderately hypersensitive dentin, SHARP instruments only should be used, but these should never be sharp- ened in the presence of the patient, for reasons which are obvious. The cutting should be done by quick, light, and sure movements, as such cut- ting is decidedly less painful than slow, heavy, scraping movements of the instrument. The direction of the cutting should, for the same reason, HYPERSENSITIVE DENTIN. 187 always be from the centre of the cavity towards the periphery, and never towards the pulp. If burs driven by the dental engine are used, these should be sharp and clean -cutting, as dull burs, or those which clog and do not cut freely, engender heat by friction, and thus increase the pain incident to the operation. If the bur be revolved at a high rate of speed, and the contact with the sensitive dentin made by light, quick touches, this tissue may be removed with so little pain as to be quite tolerable. The dread, however, of the dental engine has been induced by the reverse of this method of operating. If the operator prefers to prepare the cavity in the moist state, it will be found that if a continuous stream of warm water be thrown into the cavity while excavating with the bur, the pain will be greatly mitigated. On the other hand, if the dry method be adopted, it will be found that the more nearly complete desiccation is obtained the less will be the pain experienced. In those cases in which the hypersensitive condition is so great as to render the operation of cavity preparation by the foregoing methods in- tolerable, treatment, either local or constitutional, must be instituted to temporarily mitigate or palliate the suffering. This treatment may con- sist of the exhibition of certain therapeutic remedies, chemical agents, or anaesthetics, either local or general. PALLIATIVE TREATMENT. The treatment of the hypersensitive dentin by palliating remedies applied locally is sometimes beneficial in i^elieving the pain of excava- tion. The available drugs for this purpose are morphia, veratria, atropia, cocaine, cannabis indica, and chloretone. As neither of these remedies produces any immediate effect, it is customary to seal them in the cavity — after the thin enamel edges have been removed and the softest portions of the decayed dentin have been lifted out — with gutta-percha or zinc oxyj)hosphate for two or three days or longer, when on removing the temporary filling it will be found that the hypersensitive condition has been materially lessened. Morphia sulphas and mofphia acetas are both used for this purpose, but the writer prefers the acetas, as it seems to give the best results. To prepare the morphia for this purpose it should be rubbed up in glycerol, an eighth of a grain of morphia to a drop of glycerol. The cavity should first be neutralized by irrigating it with an alkaline solution, preferably sodium bicarbonate. The rubber dam should then be adjusted, the cavity dried, and the morphia paste carried into the cavity and spread over its walls, after which the temporary filling should be introduced. The writer prefers the zinc oxyphosphate, for tlie reason that by mixing it soft it can be introduced without i)ressure, and this is an important advan- tage in those cases in which the dentin is exceedingly sensitive. Veratria is prepared in the same manner, — one-twentieth of a grain in sufficient glycerol to make a thin paste, — spread .over the surface of the cavity, and sealed in with cement The veratria acts by producing paraly- sis of sensation in the dentinal fibril! ee. 188 OPERATIVE DENTISTRY. Atropki sulphas, one-sixteenth of a grain, may be prepared and intro- duced in the same manner and often with good results. Atropia applied locally relieves x>ain and sensitiveness by its paralyzing effect upon the peripheral nerves, and doubtless acts in the same manner upon the denti- nal fibrillse. Cocaine citras and hydrochloras, one- eighth of a grain in glycerol, ap- plied as above, sometimes i:)rove efficacious in overcoming the sensitiveness producing local anaesthesia of the dentin. Cannabis Indica — fluid extracts — applied upon cotton and sealed into the cavity will also sometimes give relief. Chloretone is perhai3S the most efficient remedy for this purpose that has as yet been introduced to the profession. It is employed in solution as a local application to hypersensitive dentin. The solution is made by mix- ing equal parts by weight of sulphuric ether and the crystals of chloretone. The chief objection to the use of these remedies is the great length of time which is required for them to act. This is explained by the exceed- ingly small amount of organic material in the dentin and the low absorp- tive powers possessed by this tissue. Constitutional palliative treatment consists in the exhibition of such drugs as, by their sedative and analgesic action, will measurably obtund general sensation for a short period of time. These are morphia, chloral hydrate, potassium bromide, and whiskey combined with some of them for its stimulating effect. The following formulae have been found by the writer to be very useful for this purpose : li Morphia sulph. , gr. \ ; Bourbon whiske)^ f ^i. Sig. — Twenty minutes before operation. For an adult. R Croton chloral hydrate, gr. x ; Bourbon whiskej'', f ^i. Sig. — Thirty minutes before operation. For an adult. R Potassium bromide, gr. xx to xxx ; Cinnamon-water, f ^i. Sig. — Thirty minutes before operation. For an adult. R Potassium bromide, gr. xv to xx ; Croton chloral hydrate, gr. x ; Cinnamon-water, f §i. Sig. — Thirty minutes before operation. For an adult. CHEMICAL TREATMENT. The treatment of hypersensitive dentin by chemical agents includes the application of caloric by means of heated air and such coagulants as carbolic acid, zinc chloride, caustic potassa, chromic acid, nitric acid, and silver nitrate. Arsenic and cobalt have also been recommended for the purpose of obtunding hypersensitive dentin, but the dangers which are HYPERSENSITIVE DENTIN. 189 likely to follow their use— viz., of destroying the vitality of the pulp aud ultimately producing discoloration of the tooth — should render the exhibi- tion of these drugs for such a purpose entirely inadmissible. Heated Air. — This means of obtunding hypersensitiveness of the den- tin was first suggested by Brockway "^ (1872). It is perhaps the most gener- ally efficient and safest means by which the dentin may be temporarily deprived of its sensation.. The therapeutic effect is produced by the abstraction of a portion of the water contained in the dentinal tubuli, or, in other words, by a partial dehydration, which renders the dentinal fibrillse less caj)able of transmitting sensation. Were it possible to com- pletely dehydrate the dentin, complete suspension of sensation would be the result. More or less complete dehydration of the exi)osed surface of the dentin can be accomplished, but this process cannot be carried to any considerable depth, neither is it necessary, for usually the hypersensitive- ness is markedly relieved under a partial dehydration of the exposed surface. In using this means of obtunding hypersensitive dentin the rubber dam should always be used, first, to exclude the outside moisture, and secondly, to protect the soft tissues from the heated air. Fig. 313. Hot-air sj^riuge. The cavity is then dried with bibulous paper and pellets of amadou, after which the heated air may be thrown into the cavity from one of the variously formed air syringes. Fig. 313 represents the ordinary form of warm-air syringe, the cylinder of which is heated over an alcohol flame or a Bunsen burner. This cylinder contains a carbon core which greatly increases its heating power, and thus by means of the rubber bulb a con- tinuous stream of heated air can be carried through the nozzle into the Fig. 314. cavity. Another form of syringe, in- vented by Dr. S. G. Perry, is shown in Fig. 314. Care is necessary in the use of this instrument not to cause pain by overheating the surface of the Perry hot-air syringe. dentin. The blast of air first thrown into the cavity should not be above a degree of heat that would be toler- ated by the unprotected skin upon the back of the hand. In fact, the writer always tests the degree of heat to be first applied in this manner. As the process of dehydration goes on, the heat may be gradually increased until a degree can be painlessly used that could not be tolerated by the * Dental Cosmos, vol. xiv. p. 19. 190 OPERATIVE DENTISTRY, skin. A certain anionnt of skill lias to be obtained in order to direct the blast of heated air in such a manner as to cause the least pain when it comes in contact with the hypersensitive dentin. If the nozzle of the syringe is held too far away from the cavity, the heated air in passing through the surrounding atmosphere becomes cooled and thus causes pain ; while, upon the other hand, if it is held too near, the blast is liable, by its high degree of heat, to cause equally severe pain. In applying heated air it is best to begin gently with a single short blast, repeated at intervals of a few sec- onds, but as dehydration progresses the length and force of the blast may be increased and at shorter intervals until the pain ceases. Fig. 315. Improved electric hot-air syringe. Another instrument for this purpose is shown in Fig. 315. This syringe has a glass nozzle in which is a spiral loop or platinum wire, con- nected by flexible copper cords to a low voltage electric current. The platinum loop can be heated to any degree desired, and by pressure upon the rubber bulb attached to the opposite end of the instrument a con- tinuous stream of air is made to pass over the heated loop and through the nozzle. To protect the lips from being burned with the hot nozzle it is covered with a perforated metal shield. With this instrument it is possible to maintain an even degree of heat for any length of time, and this is a very great advantage. Some operators prepare the cavity for dehydration with heated air by first wiping it out with absolute alcohol, as this has a strong affinity for water. In severe cases of hypersensitiveness which the employment of heated air does not relieve, and such cases are not infrequently met with, the crystals of carbolic acid may be applied to the cavity and followed by the heated air blast, at short intervals, for two or three minutes. This treat- ment will, in many cases, give complete relief, and yet it cannot always be relied upon to do this. Carbolic Acid. — This remedy when used alone has but very little im- mediate effect in obtunding hypersensitive dentin, but when used as above suggested, or when combined with oil of cloves in the proportion of two parts of carbolic acid to one of oil of cloves, its efficiency is increased. Both carbolic acid and oil of cloves have slightly local anaesthetic proper- ties, but when combined, this property seems to be greatly increased. Carbolic acid also coagulates albumin, and this property may effect the conducting power of the fibrils with which it comes in contact. The best results, however, are obtained with this combination by seal HYPERSEIsSITIVE DENTIX. 191 ing it into the cavity with zinc oxyphosphate cement for three or four days. Carbolic acid combined with tannic acid to form a thin j^aste is many times of service in treating these cases, if allowed to remain in the cavity for a few days. In apj)lying this combination the cavity should be lined with the paste and sealed in with zinc oxyphosphate cement. Zinc Chloride. — This is one of the oldest and possibly the most effi- cient local remedy for obtunding hypersensitive dentin in the whole arma- mentarium of the dentist. It must, however, be used with the greatest caution and good judgment, on account of its escharotic action and its irritating effect u]3on the dental pulp. It should, therefore, be interdicted in all deep cavities, and under no circumstances placed in close proximity to a living pulp, if it is desirable to conserve its vitality. The therapeutic action of zinc chloride is due to its affinity for water and its coagulating properties upon albumin, both of which have an ob- tunding effect upon the dentinal fibrillie. When using zinc chloride the rubber dam is indispensable, and it should be so adjusted that there will be no possibility of leakage of fluids from the mouth into the cavity, or of the zinc chloride coming in contact with the soft tissues of the mouth. After drying tlie cavity in the ordi- nary manner, the zinc chloride is applied upon a pledget of cotton to the walls of the cavity, and allowed to remain in position for five or ten minutes, or until pain ceases. As soon as this stage has arrived the opera- tion of excavation may be entered upon. It is best, however, to remove the excess of the zinc chloride first by drying with bibulous paper, and then to irrigate the cavity to terminate the action of the agent, as its strong affinity for water quickly deprives the tissue of any remaining portion. Its coagulating effect upon albumin prevents it from penetrating to any considerable depth, and therefore makes it a comparatively safe remedy to employ in all but deep-seated cavities, or when the pulp is nearly exposed. The pain is often intense for a few moments after the introduction of this remedy into the hypersensitive cavity, but this gradually subsides, and usually in a few minutes entirely passes away. If, however, the pain continues, it maj sometimes be controlled by the application of heated air, or of carbolic acid, or of both combined. Its greatest sphere of usefulness is in the superficial cavities at the labio- and bucco- cervical margins of the incisors, cuspids, and bicuspids. When employing it in the approximal cavities of the incisors, especially in children whose age would indicate that the process of calcification was not fully completed, caution should be exercised not to cause irritation of the pulp, as the cornua in these cases often lie quite near to the surface. Occasionally cases will be found in which this agent does not seem to act with any immediate effect ; but if the excess of the agent be removed with bibulous paper, and the cavity dried as thoroughly as may be by this means, and then closed with gutta-percha or zinc oxyphosphate, it will be found that in two or three days the carious dentin can be removed without pain, or only such slight sensations as are readily tolerated by the patient.. 192 OPERATIVE DENTISTRY, Zinc chloride, to be most efficient, should be chemically pure. The fused form is the best, and this should be liquefied b}^ the addition of just sufficient distilled water to produce this effect. It should be kept in a tightly stoppered bottle, as the drug has such an affinity for water that it will abstract it from the atmosi^here. Some operators prefer to obtain the obtunding effect of the zinc chloride by filling the cavities with zinc oxychloride, and allowing it to remain for a few weeks, when the hypersensitive condition will have been greatly lessened or have entirely disappeared. In this cement there is usually an excess of the zinc chloride which has not combined with the oxide, and as a consequence it is free to act upon the organic matter in the dentin. This method is, however, inadmissible in all deep cavities in vital teeth, for the reasons already mentioned. Caustic Potassa. — Caustic potassa combined with carbolic acid in equal parts (Robinson's remedy) often serves a good purpose in obtunding hypersensitive dentin. The rubber dam should be applied to protect the soft tissues, and the remedy introduced upon a pledget of cotton. This often causes sharp, stinging pain, which usually subsides in a few moments. Its obtunding action is increased by the application of a blast of heated air. Chromic acid and nitric acid have both been recommended as obtundents of hypersensitive dentin. Their escharotic action is so great, however, as to make them dangerous agents to use, while their decalcifying effect upon tooth structure is so strong that great care must be exercised to counteract this effect by the use of alkaline solutions immediately afterwards. The soft tissues should be protected from injury by the rubber dam, and the agents introduced into the cavity by means of a platinum- or gold-pointed instrument. These agents are only admissible in very shallow cavities, for the reasons just stated. Chromic acid acts by coagulating the organic elements of the dentin, while nitric acid decomposes the tissue. Silver nitrate is used for obtunding hypersensitiveness of the dentin in superficial cavities and cervical hypersensitiveness resulting from recession of the gums, but it is not admissible except in the posterior portion of the mouth, where the black discoloration produced by it would not be objec- tionable. Two, and sometimes three, applications are necessary to en- tirely obtund the sensation. Moisture should be excluded, and the soft tissues protected during its application. A fifty f)er cent, solution of the drug is applied to the cavity or the sensitive part of the tooth upon a pledget of cotton, and allowed to remain in contact for a few moments, after which the excess may be removed with bibulous paper and the parts irrigated with water. Local anaesthesia of the dentin may be produced by ether or rigolene sprayed upon the tooth, but, as a rule, the pain produced in the early stages of the process by the intense cold is often greater than the pain ex- perienced in operating uj)on the hypersensitive dentin in its original state. The danger also exists in treating these cases by this means, of producing inflammation, and finally devitalization of the pulp through the irritation of such severe thermal shock. CHAP TEE XIV. CATAPHORESIS. Cataphoresis, electric osmosis, aud electric transfusion are terms which have been applied in electrophysics to certain phenomena, by which the direct or galvanic current of electricity seems to convey fluids and chemical substances in solution through animal membranes and tissues, and deposits them at the poles. The physical phenomena of natural osmosis, whereby fluids of unequal density pass through animal membranes and tissues in a direction from the lighter to the denser fluid, illustrates the process of catai)horic action. If two fluids of unequal specific gravity be separated by an animal mem- brane, and the positive pole or anode of the galvanic current conveying ten to fifteen milliamperes be placed in one, and the negative pole or cathode in the other, it will be found that the fluid in contact with the anode will rapidly decrease in quantity, while that in contact with the cathode will be increased in volume. This is, however, seemingly some- thing more than simply the natural x^hysical phenomena of osmosis, accel- erated by the action of the electric current, for the direction of the move- ment of the fluid is controlled by the positive current, — viz., it flows from the positive to the negative pole. But if the current be reversed the volume of the fluid is changed at once by the denser fluid being carried into the partition containing the lighter fluid, thus reversing the estab- lished order of the movement of fluids in natural osmosis, and this phe- nomenon may be produced again and again at the will of the experi- menter. This power of conveyance of chemic elements possessed by the direct current is not confined to substances of elementary form, but may in many instances be applied to substances of very complex chemic structure, as, for instance, cocaine (Cj^HjiI^Oj, or methyl-blue (CigHigX.SCl) , which may be conveyed as molecules. On the other hand, certain chemic substances may be conveyed through animal membranes and tissues, but on coming in contact with the opposite pole are decomposed by the electrolytic action of the current and the radicles or individual elements set free. For instance, if a pellet of absorbent cotton saturated with a neutral solution of ])otassium iodide (KI) be placed upon the cathode, another piece of cotton soaked in distilled water be placed upon the anode, a piece of animal membrane, like chicken- skin, be placed between them in contact with the cotton upon each electrode, and a current of from ten to fifteen milliamperes be made to pass for about fifteen minutes, no change will be noticed at the cathodal electrode, but the cotton at the anode and the surface of the membrane lying in contact with this pole will be found to be slightly colored with iodine. 13 193 194 OPERATIVE DENTISTRY. This seems to prove, Jirsf, that the potassium iodide travels under the influence of the direct current from the negative to the positive pole, and secondly, that in all probability this chemic compound is conveyed through the membrane in a molecular form as potassium iodide, and upon reaching the anodal electrode is decomposed by the electrolytic action of the current, and the iodine is set free. On the other hand, if the potassium iodide solution be placed at the anodal electrode, the cotton at the cathode be soaked with distilled water only, and a current be turned on of the same strength and for the same length of time, no change will be observable in the color of the cotton at the cathode, nor of the cathodal sui-face of the membrane, while at the anode the cotton will be deeply stained with iodine. In illustration of the conveying j)Ower of the direct current applied to the more complex chemic compounds, cocaine (Cj^H.^ioSTOJ may be taken as a fair sample of these compounds. If Si four per cent, solution of cocaine hydrochlorate be placed in contact with the surface of the skin by means of absorbent cotton, disks of blotting-paper, sponge, or other absorbent material, it will have little or no effect in obtunding sensation, although it may be kept in contact for an hour or more. Let this same solution, however, be applied in the same manner, and then pass a direct current of from fifteen to twenty milli- amperes through the tissues, the anode being placed in contact with the substance containing the cocaine solution and the cathode at some other point, the cuticle in the region of the anode will in a very short time be found to be thoroughly anaesthetic, and will remain in this condition for from several minutes to as many hours, the period of anaesthesia depending upon the strength and density of the galvanic current employed, the dura- tion of its application, and the per cent, of the cocaine solution which had been applied. Another simple experiment illustrating the conveying power of the direct current is made with methyl-blue. Take two open-mouthed jars having the capacity of one or two quarts. Half fill each of these jars with distilled water, adding a small quantity of methyl-blue, sufficient to slightly tint the water. Then place the anode in one jar and the cathode in the other. If the right hand be now immersed in one jar and the left in the other, thus completing the current, and be permitted to remain for twenty ndnutes, while a current of ten to fifteen milliamperes is allowed to pass through the circuit, it will be found at the expiration of this period that the hand which had been placed in the jar with the anode will be deeply stained with the methyl-blue, the pigment having penetrated the hair-follicles, sweat-glands, and cutaneous crevices, producing a discolora- tion which cannot be washed away, and will remain for several days ; while the hand which was immersed in the jar containing the cathode can be readily cleaned by a simple washing. When this peculiar power or expression of electric force possessed by the direct current is applied to therapeutics, it is used to convey medicinal substances in solution which have been placed in contact with the positive electrode, — anode, — or with the negative electrode,— cathode,— into the CATAPHOEESIS. 195 tissues of the body or through them, with the object of securing the local effect of such remedial agents. In dental surgery this may be applied to decolorizing or bleaching devitalized teeth, in sterilizing the dentin, or producing local anaesthesia in sensitive dentin. The power of the galvanic current, however, is not limited to the con- veying of medicinal substances in solution, but it may be employed to transfer substances already in the tissues, whether of normal or abnormal comj)Osition, from one part of the body to another, or from the deeper tissues within any part of the body to the surface, with the object of en- tirely removing such substances. The fluids of the body and many medicinal substances, when subjected to the electrolytic action of the direct current, flow in a constant direction from the positive to the negative pole, but certain other chemical sub- stances, which may be dissolved or held in suspension in the fluids of the body, applied to the surface, have been found to travel in an opposite direction, — viz., from the negative to the positive pole. At the present time the subject of cataphoresis is still more or less in the experimental stage, and the electric affinity or direction in which the various medicinal agents will travel when subjected to the galvanic current has only been determined for a few of them, so that it becomes necessary to establish this fact by experiment for each new remedy used before attempting to apply it cataphorically. The phenomena which are included under the term cataphoresis, or electric osmosis, ' ' must be regarded as the result of several causes oper- ating at the same time and more or less interdependent, since certain of these phenomena are electrolytic, some mechanical, and others chemical." * Most physicists explain or base their explanation of the phenomena of cataphoresis upon the law first discovered by Thales about 600 B.C., — viz., that amber when briskly rubbed attracted light bodies like chaff and bits of paper. This law is now expressed as follows : ' ' When a dif- ference of potential is established by a direct current of electricity sent through a collection of molecules, each atom or molecule of any substance that is free to move deports itself according as the electric charge which it receives is j)ositive or negative. Those ions, atoms, or molecules with a negative charge will move towards the anode, and those with a positive charge towards the cathode." f The direction, therefore, according to this law, in which a remedy in solution will be conveyed by the application of the galvanic current, whether from the positive to the negative pole or the reverse, will depend upon the electric affinity of the disassociated ions, or, in other words, upon the initial charge which they have received. There is a question, however, in the minds of some physicists as to whether this is not the real explanation of cataphoric action, rather than that the current by its electromotive force or driving power forces the * Lectures, National School of Electricity, t Ibid. 196 operativp: dentistry. remedy in solution into the tissues, as was generally supposed a short time ago. Among the chemical substances which have been proved upon good authority to be conveyed into the tissues when applied by the anodal electrode of the galvanic current are cocaine hydrochlorate, aconitine, tincture of aconite, helleborine, mercuric chloride, mercuric succimide, lithium chloride, strychnia nitrate, strychnia sulphate, menthol, and thy- mol, while sulphur, eosine, potassium iodide, and the bromide salts are conveyed from the cathodal electrode. Electrolysis. — Many chemic substances and comj)ouuds are decom- posed by the action of an electric current, while the liberated elements show different attractions, some of them travelling to the positive pole, others to the negative. This phenomenon of dissolution is denominated electrolysis, the com- pound decomposed or acted upon an electrolyte, and the products of elec- trolysis are termed ions. The elements thus liberated are attracted to one or the other of the poles -, those which are attracted to the positive pole are called anions ; those attracted to the negative pole are designated cations. As an illustration of the electrolytic decomposition of chemic substances the familiar experiment of decomposing water by the action of an electric current may be cited. In this case the elements composing the water are dis- associated, and the ions immediately seek their electric attraction, the hydro- gen — which is a cation or electropositive element — collecting in the form of bubbles at the negative or cathodal electrode, and the oxygen — an anion or electronegative element — gathering at the positive or anodal electrode. In carrying this phenomenon a step farther to more complex chemic substances, it is found that '■ ' by passing a galvanic current from a primary battery or from a dynamo, through a liquid containing a metallic salt in solution, such as nitrate of silver, the metallic salt is decomposed, the metal being deposited upon the cathodal electrode, while the nitrogen enters into other compounds, as with oxygen, forming nitric acid, which accumulates at the anodal electrode." * Decompositions of the same general character take place in all com- pound solutions, regardless of their degree of density, whenever they are made a part of the circuit of a galvanic current. The chemic constitution of such solution immediately begins to undergo electrolytic dissolution ; the acids, oxygen, chlorine, and the electronegative elements collect about the positive electrode, while the alkalies, hydrogen, and the electro- positive elements collect about the negative electrode. '•If these terminals or poles in contact with the solution are suitably devised electrodes, and the solution is some one of the tissues of the human body, — for such tissues, though differing in density, are bathed in liquids and permeated by them, — physical effects similar to those just described follow the passage of the current, the result depending upon the nature and composition of the tissues involved, the strength of the current, and the length of time it is permitted to flow." f * Lectures, National School of Electricity. f Ibid. CATAPHORESIS. 197 The character of the changes which take place in the electrolytes- fluids or animal tissues — at distant points from the electrodes in the track of the current is not known, while ''it is difficult to account for the phe- nomena of decomposition which takes place at the electrodes without as- suming that some kind of rearrangement of the molecules composing the electrolytes occurs along the entire track of the current." -'^ Anodal Electrolysis. — This term is used to designate those phenom- ena which take place at the positive pole, or anode, as a result of the appli- cation of a galvanic current to or its passage through the tissues of the living human body. Its action may be experimentally shown by taking a piece of fresh, lean meat and passing a needle into it which is connected with the positive pole or anode of a galvanic current having a strength of from five to ten milliamperes, the cathode being placed upon the opposite side. After the current has been allowed to pass for a few minutes, it will be noticed that at the point of insertion of the needle the meat has become dry, white, and shrunken. The extent and depth to which this effect may be carried into the tissue will depend upon the strength of the current, the length of time it is employed, and its density, the latter being determined by the size of the needle or anodal electrode. This effect in a measure is the result of the coagnlation of the albuminoid substances contained in the tissues from the action of the acids collected at the anode, and partly to cataphoresis, or the electric affinity of ions possessing an electropositive charge, which directs them to the cathodal electrode. If the needle or anode is made of a material that is not readily oxidized — like gold or platinum— and is not materially acted upon by acids or chlorine, no change other than that just mentioned is observable in the tissues ; but if the needle employed is of iron, steel, or copper, salts are formed, and the tissues in its immediate vicinity are stained by a deposit of the oxide or oxychloride of the metal used. The drying of the tissues in the vicinity of the anode is due to the cataphoric effect of the current which carries the fluids towards the cathode, or to the migration of electropositive ions which seek their affinity at the negative pole. This phenomenon may be illustrated by passing a galvanic current through a piece of wet clay. In a few minutes the surface of the clay in the vicinity of the anode will begin to show signs of drying and hardening, while at the cathode the mois- ture will collect in increasing quantity and softening of the surface take place. It may be stated briefly, therefore, that the effect of anodal electrolysis upon animal tissue is destructive, but that this destructive action may be employed to advantage in the treatment of various pathologic con- ditions where this destructive effect, if judiciously used, would retard or entirely arrest the progress of the diseased condition. The phenomena of anodal electrolysis which takes place in animal tissues are : * Lectures, National School of Electricity. 198 OPERATIVE DENTISTRY. 1. The accumulation of oxygen, chlorine, and acids in the vicinity of the electrode. 2. The tissues in contact with and immediately surrounding the elec- trode, as the result of the accumulation of the above destructive anions, suffer more or less disintegration by the disturbance of their molecular composition, which later causes structural changes and arrest of function. 3. The acids formed at the anode, reacting upon the albuminoid sub- stances and other organic elements contained in the tissues, produce astrin- gent, styptic, Meaching, and coagulating effects upon those parts with which they come in contact. 4. When the electrode is made of some material which is readily oxidized, or has a strong affinity for the acids which collect about it, secondary chemical compounds are formed, like oxide or chloride of iron, of copper, or of zinc, as the case may be, which may possess therapeutic value or may produce indelible staining of the tissues. The therapeutic employment of the secondary products formed at the anode or cathode is termed metallic electrolysis, but this function is almost exclusively confined to the anode. Anodal electrolysis has a wide range of theraj)eutic application in both general and special surgery. In dental surgery and stomatology it may be applied to the removal of cysts and new growths upon the tongue or oral mucous membrane ; to hemorrhagic conditions of this membrane, and in hemorrhage after extraction ; to phagedenic ulcers, follicular diseases, and inflammatory conditions due to low forms of bacterial life ; to the local treatment of pyorrhoea alveolaris ; to the production of aseptic conditions in devitalized and suppurating teeth, and to decolorizing or bleaching de- vitalized teeth. Cathodal Electrolysis. — This term is used to designate those phe- nomena which take place at the negative ])ole or cathode as a result of the application of a galvanic current to the tissues of the body. When such a current is x>assed through the compound solutions which compose a larger part of every animal tissue, the constituents -of the tissues in the immediate* vicinity of the cathode are decomposed, the hydrogen and the alkali ions gathering about the cathodal electrode. The alkalies which are thus collected are principally soda and potassa. Inasmuch as these substances do not jDOSsess chemic affinity for the metals generally used for electrodes, with perhaps the exception of aluminum, which is corroded by the alkali ions, forming aluminates of soda and potassa, but which do not seem to possess any therapeutic value when locally applied, it only becomes necessary to consider the action and dis- l^osition of the hydrogen and the alkalies. If a piece of fresh meat or egg albumin be subjected to the action of a galvanic current, it will be ob- served that the hydrogen gas which collects at the cathode will bubble up and escape, or be detained in the meshes of the tissues, while the soda and potassa will unite with the albuminoids of the tissues immediately sur- rounding the cathodal electrode, causing softening of these tissues, and if continued for a sufficient period of time in the living body, disintegration, loss of vitality, structural changes, and liquefaction will take place. CATAPHORESIS. 199 The phenomena j)resented by cathodal electrolysis, therefore, are : 1. The accumulation of hydrogen and alkalies in the vicinity of the electrode. 2. The presence of hydrogen gas in the meshes of the tissues or its escape, and the union of the alkalies with the albuminoids of the tissues. 3. The softening of the tissues in the neighborhood of the electrode and their final liquefaction. From the foregoing- statements it will be observed that the phenomena of cathodal electrolysis are also destructive in their nature to the living tissues when much prolonged, and yet these phenomena when skilfully applied to certain pathologic conditions are capable of being rendered most beneficial. Cathodal electrolysis has its greatest usefulness in the softening and re- laxation of cicatricial tissue, in the reduction of hyperplasias and other inflammatory growths, in the removal of fungous growths, and in the treatment of bony and cartilaginous enlargements, especially of the nasal passages, the alveolar processes, and the palate. Ordinarily the electromotive force required for electrolytic work will not exceed twenty volts, but the resistance of the tissues is so variable that a current of the strength of ten to fifteen milliamperes is not infre- quently employed, making a greater electromotive force necessary for the most efficient work. THE GENERAL PRINCIPLES OR LAWS WHICH GOVERN THE GENERATION AND TRANSMISSION OF ELECTRICITY, Generation. — Electricity may be generated, first, by friction, when it is termed frictional or static electricity ; secondly, by chemic action, when it is termed chemic electricity ; thirdly, by induction, when it is known as induced electricity. ThQ first is a form of electricity used largely in medicinal practice, and is generated by a machine in which a glass disk is made to revolve rapidly while in contact with specially prepared rubbers, the electricity being col- lected and stored by apparatus adapted to the purpose. The second or chemic electricity is generated by primary or galvanic batteries. Primary batteries, of which there are a number of different forms, are composed of two plates of different metals, —^/ie elements, — as copj)er and zinc, or of one metal and a non-metallic substance, as carbon, which are placed in ajar containing a liquid — the electrolyte — composed of a solution of sulphuric acid or of ammonium chloride, zinc chloride, or other suitable solution, the two plates being connected together outside of the liquid, when, by the chemic action taking j)lace between the elements and the electrolyte, a current of electricity is generated. This constitutes a cell of a primary or galvanic battery. A battery may be composed of a single cell or any number of cells joined together in series by connecting with copper wire the negative pole of one cell to the positive pole of the next, and so on until the series is completed. The wire or cord attached to the copper element of the first cell would be the xmsitive pole, while that 200 OPERATIVE DENTISTRY. attached to the zinc element of the last cell would be the negative pole. The current travels in the outside circuit from the jjositive to the negative pole. The poles are determined by the direction in which the current flows ; the plate from which the electric current flows outside the liquid is termed the positive pole, while the plate to which the current returns out- side the liquid is denominated the negative pole. In a cell composed of copper and zinc elements, with dilute sulphuric acid as the electrolyte, the zinc is most violently acted upon, and the electric current generated flows from the zinc or positive element through the liquid to the copper or negative element, and from that through the external conductors or wires back to the zinc element, thus completing a circuit. That portion of the zinc plate which is immersed in the electrolyte is positive to that part of the copper plate which is likewise immersed, but the portion of the copper plate above the liquid is positive, while the same portion of the zinc plate is negative. To indicate these conditions the signs plus (+) and minus ( — ) are used. Primary batteries are divided into two classes, — viz., open circuit and closed circuit batteries. The open circuit battery is one which works best when not in constant use, and is usually employed for call-bells and signal circuits generally. The ^ ' Leclanche' ' is the best of this class of batteries. In this the elements used are zinc and carbon ; the electrolyte is a solution of ammonium chloride ; the carbon, being placed in a porous jar and sur- rounded by powdered manganese dioxide, is suspended in the liquid in the centre of the battery jar, and the zinc element is suspended at one side. This form of battery, if made to work continuously, soon runs down, and must be given a period of rest before it can be used again. When only brought into action for brief x)eriods at a time it works most satisfactorily. The electromotive force of such a cell is about 1.47 volts. The class of batteries known as closed circuit batteries comprise those varieties which work best when in constant service. The "gravity" battery, which is a modification of the "Daniell," is the best of this class. The gravity battery is formed by placing the copper element in the bottom of the battery jar and suspending the zinc element from the top ; these are cast in the form of a wheel or " crowfoot." A cupric sulphate solution is then poured over the copper element, and a quantity of cupric sulphate crystals added. Upon this solution is carefully poured a solution of zinc sulphate. The specific gravity of the two solutions is so different that they do not readily mix ; the cupric sulphate solution, being the heavier, remains at the bottom of the jar. The zinc sulphate solution takes the place of the sulphuric acid in the Dauiell' s cell, and although it does not give quite so high a voltage, the action of the cell is more even and constant. The potential of such a cell is from 1 to 1.14 volts. The dry cell battery is made either upon the principle of Zamboni' s dry voltaic pile, or some such substance as sand, sawdust, or paper, moistened with acidulated water, separates the elements in each cell. Secondary or storage batteries are composed of two or more plates of the same metal, — generally lead, — which are placed in a solution which, under ordinary circumstances, does not attack the metal, — usually dilute sulphuric acid, — and consequently no electricity is generated. But if a current of CATAPHORESIS. 201 electricity, generated from some outside source, like a dynamo furnishing a one-hundred-and-ten-volt electric lighting current, is allowed to pass through the battery, a chemic action is set up in the solution termed charging^ which decomposes it and causes plumbic dioxide (PbO,) to be de- posited upon one plate and metallic plumbum (Pb) in a spongy form upon the other. This forms a battery of two different elements, — viz., PbO^ and Pb immersed in an electrolyte, hydric sulphate (H.SOJ — sulphuric acid — of full strength and specific gravity, which is capable of acting upon them. The lead plates which form the element must be so constructed as to present a large surface upon which the chemic action may take place, as the amount of energy which can be stored in a cell depends upon the capability of the plates to appropriate the results of the chemic action. If the poles of the battery are now brought together and the circuit closed, a current of electricity will be immediately generated. In the chemic action which takes place during the discharge of the battery, one atom of oxygen (O) contained in each molecule of the PbO^ will pass to the opposite plate, joining with the Pb and forming plimibie oxide (PbO). This process continues as long as any molecule of PbO^ remains upon the surface of the plate to give up its oxygen. When no more oxygen is liberated both plates become alike (PbO) over the entire surface. The sulphur radical in the electrolyte (H^SOJ enters into combination with the active material on both plates, forming plumbic sulphate (Pb^SOJ, the specific gravity of the electrolyte being correspondingly reduced. When all of the active material has been changed in this manner the cell is said to be discharged, for an equilibrium has been created between the two plates and the electromotive force is reduced to zero, and so remains until it is again charged by an electric current from the outside. Secondary batteries discharge their electric current in an opposite direction from that in which they were charged. Like primary batteries, the potential or electromotive force does not depend so much upon the size of the elements as upon the materials composing them and the nature of the electrolyte ; but the amount of the electric energy furnished by any cell will depend upon the area of the surfaces of the elements exposed to the action of the electrolyte. The electromotive force of the charging current should be about twice as high as that of the cells to be charged. On the other hand, the amount of current charged per hour should not exceed what is called the normal charging rate, and which differs according to the size of the cells. The normal rate of charge for small storage batteries is about ten hours, and if a cell has a capacity of fifty ampere hours, not more than five amjDeres should be charged, and for a cell of one hundred ampere hours, not more than ten amperes should be charged. The rate of charge should be preferably kept at normal or under, as continuous charging at a higher rate than normal would injure the plates. Storage batteries, however, have never come into general use for medi- cal or dental purposes, and although they have been used to some extent 202 OPERATIVE DENTISTRY. for heating cauteries and lighting exploring lamps, they are by no means a convenient or economical method of obtaining an electric current. Induced Electricity. — This form of electric current is produced by dynamo-electric machines, and is the common current now used so exten- sively for illuminating and power purposes. There are two general classes of dynamo -electric machines ; one class produces an alternating current^ and the other a continuous current. The modern Edison dynamo-electric machine so generally used all over the world for lighting houses and shops and running small motors delivers a continuous current. This current is often used for thera- peutic purposes by the physician, surgeon, and dentist. The current delivered by such a dynamo differs from that delivered from the primary battery in that it has a slight but uniform variation in strength. The strength of the current coming from a primary battery may be represented by a straight line, while that from the dynamo would be by comparison represented by a line waving slightly but uniformly. It has not been definitely determined whether this difference in the current has any effect upon the constituents of the body, but so far as known they seem to act alike. The most convenient dynamo current for therapeutic uses is the Edison direct current of one hundred and ten volts. The pressure of this current varies from one hundred to one hundred and twenty-five volts, according to the position on the mains. The electromotive force can be reduced to any degree necessary to conform with the requirements of the physician, the surgeon, or the dentist by lami3S or other resistances and shunts. By employing this form of current much of the annoyance attending the operation of primary batteries is obviated, and with the now quite com- mon practice of placing the mains in underground conduits, the dangers from lightning or crossing with wires of dangerous potential is reduced almost to nil. Transmission. — Electric currents are transmitted, conveyed, or con- ducted by various substances, like metals, charcoal, graphite, fluids, ani- mal tissues, etc. Any substance which is capable of conveying electricity is termed a conductor, and those substances which do not convey it are termed non-conductors ; dry air, glass, vulcanized rubber, porcelain, etc., belong to the latter classification. In substances which are i^erfect conductors, like silver and copper, electricity moves with absolute freedom under any electromotive force, no matter how small. Copper wire is generally used as a means of conduct- ing electric currents. The conducting power of pure silver is 100, that of copper 97. In substances which are perfect non-conductors, electricity will not move under any electromotive force, no matter how great. In substances which are imperfect or partial conductors, electricity moves only upon the exhi- bition of great electromotive force, the amount of electromotive force required varying according to the ability of the substance to convey an electric current. The transmission of electric currents is through metallic conductors, CATAPHORESIS. 203 copper wire being choseu for econoDiic reasons. The resistance of these conductors is varied by the character of the metal, the cross-section (size), and the distance to which the current is conveyed. The percentage of conducting power possessed by the various metals and alloys employed in electric work is as follows : Silver, 100 ; cojDper, 97 ; gold, 75 ; aluminum, 54 ; zinc, 28 ; platinum, 17 ; wrought iron, 16 ; nickel, 12 -, tin, 12 ; lead, 8 ; mercury, 1.6 ; cast iron, 3 ; platinum silver made of two parts platinum and one part silver, 6.4 ; German silver made of five and one-half parts copper, two parts zinc, and two and one-half parts nickel, 3.5 ; German silver made of six parts copper, two and one- half parts zinc, and one and one-half parts nickel, 5 ; German silver made of five parts copper, three and one-half parts zinc, and one and one- quarter parts nickel, 7. 5. Units of Measurement. — The electromotive force, or electric pressure furnished by the cell or the dynamo, is the force which moves the current against the resistance of imperfectly conducting substances, and is termed voltage. The active eney^gy of electricity lies in a property designated as its ciir- rent strength, and is termed its amperage. The unit of quantity is the coulomb. The unit of pressure is the volt. The unit of strength is the ampere. The unit of resistance is the ohm. The unit of poioer is the ivott. A coulomh represents the quantity of electricity that passes during one second through a conductor having a resistance of one ohm, with one volt of electromotive force. A volt re J) resents the electromotive force (E. M. F.) which is required to move one amj)ere of current through one ohm of resistance. This force may be represented, for example, by the pressure necessary to move a cer- tain number of gallons of water per minute through a pipe of given size ; reduce the size of the pipe and the resistance becomes greater, thus call- ing for a greater degree of pressure to accomplish the task. An ampere represents the volume of an electric current carrying one coulomb per second ; hence it is the measure of the rate of floiv of an electric current, and, in connection with the voltage, measures the energy of the current. The measurement of the ampere of current is based upon the electro- chemical effects of currents, and is defined as that much current which will deposit silver at the rate of 0.0001118 grammes per second from a standard solution of silver nitrate in water, or which will decompose 0.00326 milligramme of water in one second. An ohm of resistance is defined as equal to the resistance of a column of pure mercury which is 106.3 centimetres long, and has a uniform cross- section which contains 14.4521 grammes of mercury, the temperature being that of melting ice. This gives the column the uniform cross-section of one square millimetre. The ohm is that degree of resistance which will allow one ampere of current to pass under a pressure of one volt. 204 OPERATIVE DENTISTRY. According to Ohtii's law, when a current of electricity flows through a wire, under the pressure from a battery or other sources of electricity, the effective strength of current ivMch flows in the circuit is equal to the pressure E divided by the resistance of the circuit. It is often written thus : C = ^5^, when Jtv C, E, and R stand for current pressure (electromotive force) and resistance, and may be read C equals E divided by E. It is evident, also, from the relation as written above, that E equal C times E, and E. equals E divided by C. By this law if any two out of the three fundamental electric quan- tities which exist in a circuit are known, the third can at once be calcu- lated. Thus, if a sixteen-candle-power incandescent lamp is known to take one-half an ampere when attached to a circuit which furnishes a current at a pressure of one hundred and ten volts, the resistance of the lamp when in operation may be calculated at once to be one hundred and ten divided by one-half, which gives the resistance of two hundred and twenty ohms. Or if two cells of a battery, each furnishing a iDressure of 1.1 volts, and each having an internal resistance of three ohms, be con- nected with an external circuit of 2.8 ohms' resistance, then the total resist- ance in the circuit is 8.8 ohms, and the pressure which acts to pass the current through the circuit is 2.2 volts. The current flowing under these circumstances is therefore one-quarter ampere (C ^ E E or \ = 2.2/8.8). A watt is the amount of power developed by a current of one ampere, having an electromotive force of one volt. It is the unit of electric worTc, and represents the poiver exerted by one ampere of current at one volt of pressure- These propositions may be written thus : Amperes = volts -^ ohms. Ohms ^ volts -H amperes. Volts = amperes X ohms. Watts = volts X amperes. RHEOSTATS ; CURRENT SELECTORS ; CURRENT CONTROLLERS. Rheostats. — Electric currents furnished by the various means already mentioned — viz., primary batteries, secondary batteries, and dynamos— need to be modified in strength in order to adapt them to the requirements of therapeutics. This may be accomplished by adding resistance to the ex- ternal current, or by diverting a portion only of the available current into the circuit with the patient. The substances which are introduced for the purpose of reducing the energy of the current by the interposition of increased resistance are selected because of their great resistance to the passage of electric cur- rents. These substances are water, carbon, graphite, and coils of German silver wire. Eheostats when constructed for therapeutic work have a mechanical device for increasing and decreasing, at the will of the operator, the amount of resisting substance in the circuit. Water Rheostats. — Water rheostats vary in resisting capacity accord- ing to the quantity and purity of the fluid admitted into the circuit. Dis- CATAPHORESIS. 205 tilled water only should be used for such purpose. The current in passing through this resistance heats the water and decomposes or electrolyzes it. If the water is impure, deposits occur or the metal i)lates may be corroded, thus impairing the usefulness of the instrument. The chief objection to this form of rheostat is the fact that there is no simple or elementary means of measuring with accuracy such form of resistance. In the water rheostat one pole is attached to two metal plates separated by about three-fourths of an inch and placed in the bottom of the glass receptacle containing the w^ater. The other pole is attached to a sliding rod worked with a ratchet, the rod having attached to its lower end an angular plate of metal with the apex iDointing downward, — both poles should be made of platinum, — which, as it is lowered into the water, increases the surface of this pole in contact with the water, and thus de- creases the resistance. The current passes from the battery — or a suitable lamp resistance or shunt when the street main is used — through the water and the patient in series. The current is controlled by raising or lower- ing the pole having the angular plate of metal attached to its lower end. Carbon and Graphite Rheostats. — This form of rheostat is usually constructed in the shape of a broken ring, one pole being attached to one end of the ring, and the other pole to the index which travels over the circular disk (Fig. 316). These serve fairly well for modifying the cur- FiG. 316. Jewell graphite rheostat. rents from portable and stationary batteries, and also from dynamos when the amount of current used is small. They have the advantage of fur- nishing a high resistance in a very small compass, but they also have a disadvantage in that they cannot be graduated, since their resistance is variable even in instruments of the same size and shape. German Silver "Wire Rheostats. — German silver wire rheostats when well made are the most reliable and constant, and have this advan- tage over all other forms, that the resistance which they offer can be accu- rately measured. In this form of rheostat the degree of resistance is regulated by the length and the diameter of the wire, the cross-section being reduced to the smallest size which will conduct the current without overheating ; it is therefore graded with especial reference to the amper- 20G OPERATIVE DENTISTRY. age of the current it is expected to convey. In the construction of this form of rheostat two general methods are followed : one is to arrange the wire in unbroken coils between a certain number of contact points, dis- posed at equal distances from each other around a broken ring, one pole attached to one end of the broken ring, as in the graphite rheostat, and the other pole to the index which travels over the contact point. The other method is to wind the wire upon spools of fibre, one arranged as a per- manent resistance, the other as a shunt i-esistance. The coil of the shunt resistance is wound in notches of a small fraction of an inch, and a con- tact-shoe is made to move from one end of the coil to the other, and in doing so touches several hundred turns of the wire, thus giving as many different gradations of current flow. In the use of high voltage currents, such as the one-hundred-aud-ten- volt circuit, it may be switched through the coils of such a rheostat and reduced to any degree required. A cuiTent selector is a mechanical device for throwing a greater or less number of cells of a primary or secondary battery into the circuit. The amount of current can thus be made to vary as the exigencies of the case demand, while the electromotive force is gradually increased and decreased at the will of the operator. A current selector or switch of this character does not, however, do away with the necessity of a rheostat, especially if it is constructed to in- crease the number of cells thrown into the circuit by groups rather than singly. Dynamo Current Controllers. — These are resistances especially adapted to the dynamo current, either to be put in series with the patient or so constructed as to form a shunt circuit with the j)atient's circuit. In the former case the current is modified by a rheostat capable of increasing and decreasing the resistances, while in the latter the device is such as to admit a greater or less flow of current into the shunt circuit. The princi- pal difference between these methods of controlling the dynamo current is that in the former the electromotive force remains the same regardless of the amount of current the patient is receiving, while in the latter this electromotive force varies with the current received. These instruments can be so controlled that the graduation will be exact. Milliamperemeters. — Exact work in electrotherapeutics cannot be accomplished when using the direct current without the means of accu- rately measuring that current. The milliamperemeter offers the means of measuring ~ the strength of the carreut being used, and this is of first importance in cataphoric work, as it enables the operator to measure the i-esistance of the tissues in- volved in the circuit, and offers a sure means of detecting any leakage of the current, which is also important, for if it is not discovered, it prolongs the time necessary to produce the desired result or cause it to end in com- plete failure. Currents used upon the body for therapeutic purposes never exceed one-half an ampere, or five hundred milliamperes, and for nearly all cataphoric work much less than this, from five to twenty milliamperes being about the limits of the customary range. CATAPHOEESIS. 207 Fig. 317. Weston's dead-beat milliam- peremeter. Five milliamperes of current for dental cataplioresis is often more than can be used. A current strength of from two-tenths to two milliamperes is usually all that can be borne without pro- ducing pain. There are two forms of milliamperemeters in use by physicians and dentists. In one the needle is magnetic and arranged to freely turn upon a pivot, and is easily influenced by outside magnetic forces. The needle is deflected away from the earth's magnetic meridian by the electric current which traverses a coil of wire which is parallel with the magnet before the current passes. In the other the construction is such that the indi- cator comes instantly at rest, and has no period of oscillation before the measurement can be read, — in other words, it is what is termed "dead-beat." (Fig. 317 shows such an instrument.) These instruments are made with a double scale, one for strong and the other for weak currents, the scale for the weaker current being divided into twentieths of a milliampere. Conducting Cords and Tips. — The conducting cords are made of bunches of fine copper wire covered with cotton or silk, and should be pliable as well as strong and durable. If the cords are not made of good material, the strands or threads are liable to be broken with use, and the current thus be rendered fitful or interrupted by such defects. The tips or terminals are metal devices placed at either end of the con- ducting cords for attaching them to the binding posts and the electrodes. Electrodes. — These of necessity are made of various materials and of many sizes and shapes to meet the demands of special forms of treat- ment. The practical medical and surgical electrotherapeutist will need an entirely different line of electrodes from those required by the dental surgeon. Fig. 318 shows a selection of electrodes employed by the dental surgeon. ELECTEOCOOAINE ANAESTHESIA. As a means of obtunding hypersensitive dentin, ansesthetizing the den- tal pulp, and producing local anaesthesia for tooth extraction, the cata- phoric or electrolytic action of the direct electric current in carrying cocaine into the dental tissues and thus paralyzing the function of sensa- tion bids fair to become the most important means which has ever been placed in the hands of the dentist for relieving the pain of dental opera- tions. Many successes and also many failures have been reported in the^ use of cataphoresis. The failures have been the result, no doubt, of those conditions which always surround any new method of treatment, espe- cially if it introduces remedies or forces the action of which are more or less imperfectly understood, as was the case with nitrous oxide, ether, and chloroform. But in time these difficulties will be eliminated by research and experimentation, and the methods of treatment so perfected that fail- ures will become either a matter of an individual idiosyncrasy of th& 208 OPEEATIVE DENTISTRY. patient or of a lack of ability upon the part of the operator to manipu- late the apparatus. The solutions of cocaine which are used in cataphoresis vary in strength from ten to forty per cent. These solutions may be made from either the Fig. 318. '^ / Cataphoric electrodes. hydrochlorate or the citrate, dissolved in distilled water, glycerol, guaiacol, or guaiacol and ether. Morton recommends making fresh solutions for each case, because of the fact that cocaine solutions deteriorate and lose their anaesthetic property in a large measure in a few days. CATAPHORESIS. 209 Fig. 319. Apparatus. — The apparatus necessary for j^roducing electrococaine anaesthesia are a suitable primary galvanic battery ; preferably a dry-cell chloride of silver, or a dry-cell Leclanche battery, having an electro- motive force of from ten to thirty-five volts ; a reliable rheostat or con- troller so arranged that the current may be increased or diminished by slow gradations at the will of the oper- ator ; a milliamperemeter graduated to register the twentieth part of a milliampere ; conducting cords and electrodes. The secondary or storage battery is sometimes employed for producing cataphoresis. When this form of bat- tery is used the plates should be small, — three by three inches. The potential of a cell of this size will be about two volts, and the normal strength of current at eight hours' discharge is five- eighths of an ampere. The Edison one-hundred-and-ten- volt street current may also be em- ployed by suitably reducing the strength of the current. The objec- tions which have been raised to the use of this current are the dangers from severe shock, if by chance the apparatus should be defective, or lightning should strike the supply wire, or it should become crossed with one carrying a current of much higher potential. These dangers may be guarded against by placing the mains underground, as is now being done in all of our large cities, and by inserting a suitable /tm&?e wire connection in the apparatus that will not carry a current of greater strength than one-half an ampere. In the arrangement of the apparatus for cataphoric work, the battery, or other source of current, the rheostat, the milliamperemeter and the patient are in series (Fig. 320). The direction of the current being from the battery to the rheostat, from the rheostat to the milliamperemeter, from the milliamperemeter to the patient, from the patient back through the rheostat to the battery, thus making the circuit complete. The resistance encountered in the flow of the current are found in the conducting wires, the rheostat, and the tissues of the patient ; the skin and the dentin being more highly resistant than the other tissues through which the current must pass in treating hypersensitive dentin. The result of resistance to the flow of an electric current is the x^i'oduction of heat, the amount of heat produced being governed by the degree of the resist- tance, and the size and character of the conductor. Dentin is exceedingly resistant to the passage of a current of electricity, consequently heat is liable to be produced if the pressure of the current is 14 Cataphoric outfit Avithout miliiamperemeter. 210 OPERATIVE DENTISTRY. too great, aud pain would be the result. The teeth are very sensitive to an electric current, and respond vigorously to any sudden change in the pressure or strength of current- flow or amperage. There is, however, a considerable variation between individuals and between different teeth in the same individual as to the amount of current that can be used upon the teeth without causing pain. With some individuals the limit is Fig. 320. ^ "/ TttXve M.5 / \ n CCrcwvt / \ 1^ -►vrvif" r' ^>nrvrf^ '^T^tT r i J)»y B,, T,, J,y Dry CclL c.vi CcW CtVU avL reached with a pressure of four or five volts and one- tenth of a milli- ampere of current. Under such circumstances it becomes necessary to increase the pressure very slowly until the cocaine paralyzes somewhat the function of sensation in the dentin. While in others the pain limit may nnt, be attained until the pressure reaches fifteen to twenty volts, with an CATAPHORESIS. 211 amperage of from three-tenths to four-teaths of a milliampere. The anterior teeth seem to be the most susceptible to the galvanic current. Teeth having acutely inflamed pulps are also exceedingly sensitive to the current, even at very low initial voltage. Another factor in this connection which must be taken into considera- tion is the nervous irritability of the patient, which when highly exalted may render them peculiarly susceptible to the irritation of an electric current. Resistance of Tissues. — According to Dr. W. A. Price,* the average resistance of a patient is about twenty-five thousand ohms from the cavity to the hand holding the negative electrode or cathode. This was com- puted from twenty-five cases, varying all the way from ten thousand to seventy-eight thousand ohms and higher. The difference of resistance from the hand to the tooth and from the cheek to the tooth he found to be from three thousand to five thousand ohms. In one case, in which the resistance was measured with the cavity barely moist, it gave a resistance of forty- seven thousand seven hundred ohms. On applying a forty per cent, solu- tion of cocaine in water to the cavity, the resistance was reduced to twenty-eight thousand five hundred ohms, and upon transferring the cathode to the cheek it was further reduced to twenty-three thousand eight hundred ohms. The greater portion of the resistance is, therefore, according to the above statements, in the tooth. Dr. Price further states that the average resistance from the hand to the tongue with small electrodes is about nine thousand ohms, varying from seven thousand to twelve thousand ; and from the cheek to the tongue about five thousand ohms, varying from three thousand to seven thousand. This places the greater part of the resistance of the tissues of the patient in the dentin of the tooth, which varies all the way from ten thousand to seventy thousand ohms, with an average of about twenty thousand. Sections of dentin in the fresh state tested out of the mouth in an almost dry condition, and also when saturated with various solutions, gave a wide range of resistance. As an illustration, a longitudinal section of fresh dentin, five millimetres thick and almost dry upon the surface, had a resistance of thirty thousand ohms ; after drying and then saturating with a forty per cent, solution of cocaine the resistance was reduced to four thousand five hundred ohms, and after drying and saturating with a solu- tion of sodium chloride the resistance was reduced to three thousand and seventy ohms. From the statement of the foregoing facts, and the principles involved in applying the galvanic current to the human body for its cataphoric effects upon hypersensitive dentin, it becomes patent that the greatest care must be exercised in the selection of the initial degree of voltage ; in employing a relatively low amperage and carefully measuring the strength of current used ; in so controlling the current that it may be increased or diminished by imperceptible gradations ; in avoiding a breaking of the * Dental Cosmos, vol. xxxix. p. 90. 212 OPERATIVE DENTISTRY. current, or too rapidly advancing the strength of the current, and in main ^ taining a moist condition of the cavity during the flow of the current. METHOD OF ADMINISTRATION. The first step in the application of the galvanic current for electro- cocaine ansesthesia by hypersensitive dentin is the isolation of the tooth to be operated upon by means of a rubber dam, which must be securely ligated at the cervix to prevent leakage of moisture or of the current. As an added precaution against leakage, the cervix of the tooth should be coated with some quick-drying varnish. If metallic fillings are present in the tooth to be operated upon, or in the ai^proximal surfaces of the adjoining teeth included in the rubber dam, these should likewise be covered with varnish, or an extra rubber dam may be placed on the tooth to be treated for the purpose of insulating them, or otherwise the current would be dissipated from the cavity by being switched off or shunted by these conductors. The cavity of decay should be carefully irrigated with tepid water before adjusting the rubber dam, with the object of removing all the food debris and detached portions of disorganized tissue. It is not necessary to attempt to remove the carious dentin before the application of the cocaine, and the surface of the cavity need not be more than partially dehydrated. A pledget of cotton large enough to loosely fill the cavity is then satu- rated with the cocaine solution and placed in the cavity. The cathode is next placed in the hand of the patient or applied to the cheek, neck, or other suitable location. If the cathodal electrode is covered with sponge, this should be moistened with water, or, better, with a solution of sodium chloride. The anode is now applied to the cotton in the cavity and the current turned on, care being taken to start with the lowest voltage and weakest amperage. To obtain the best results from the cataphoric effect of the current the point of the anode (which should be made of platinum) should have a diameter as nearly the size of the cavity as possi- ble, but as this would necessitate purchasing a very large number and variety of platinum anodal tips, the writer uses instead platinum disks cut from ISTo. 30 gauge plate, and perforated with numerous holes for the ready passage of a reserve supply of the cocaine solution. These disks may be kept on hand in a variety of sizes and shapes at a very trifling expense. One of these disks is placed over the cotton, care being taken that it does not touch the dentin, and the anode applied to this. As a result of using electrodes with points whose cross- section nearly equals the diameter of the cavity, greater diffusion of current is secured than is possible with small points, unless metal disks are used in conjunction with them, as just suggested. Many operators have complained of their inability to secure complete anaesthesia over the whole surface of the cavity when employing catapho- resis, except by prolonged application. This is explained upon the sup- position that the surface contact area of the anode was too small to cover CATAPHORESIS. 213 the area of dentin upon which it was desired to produce anaesthesia. It is a law of electricity that the current travels by the path of the least resistance. This in the vital tooth ls by the organic matter in the tubuli and the contents of the pulp-chamber. Primary ansesthesia will therefore occur only over the radius covered by the positive pole, because the current passes directly from the anode to those tubuli which are in the direct path of the current. Secondary anaesthesia of the dentin may be secured by producing anaesthesia of the pulp, as no doubt occurred in some of those cases reported in which the anaesthetic effect of the treatment was secured only after a very long application of the current through a small pointed anode, while in others it was due to leakage of current or great density of the tooth. The anode should be constructed with a reservoir for holding a reserve supply of the solution, like Morton's tubular cataphoric applicator, or, better still, the syringe electrode of the S. S. White Company (Fig. 321). Fig. 321. Syringe electrode. Teeth which are termed soft, or imperfectly calcified, especially chil- dren's teeth, respond more readily to electrococaine anaesthesia than do that class of teeth which are termed dense, or highly calcified, as the greater amount of organic matter in the former renders them better conductors of the electric current. When the current is first turned on to the tooth a slight, uneasy sensa- tion is experienced, but this immediately passes away, and the strength of the current may then be gradually increased a fraction of a milliampere at a time, or until the j^atient again becomes conscious of the current- pressure, but under no circumstances should it be advanced to such a de- gree as to be painful. The best results are obtained with low amperage — from one to three milliamperes as the maximum — and increasing the cur- rent very slowly. As anaesthesia advances the strength of the current may be more rapidly increased, but a current strength above five milliamperes is rarely required, and, finally, when this can be done without producing unpleasant sensations, anaesthesia may be considered as complete, the switch slowly carried back to the zero point, and the operation of cavity preparation commenced. With a current above five milliamperes there is danger of decomposing the chemic structure of the cocaine, or of producing coagulation of the albuminoid elements of the dentin by electrolysis. The period of application of the current may be stated to be from eight 214 OPERATIVE DENTISTRY. to fifteen minutes in ordinary cases, but in teeth wliicli are very dense a much longer period is sometimes required. The milliamperemeter should be carefully watched during the whole period of administration. Any rapid movement of the indicator, or a registration of a greater amperage than the dentin would admit, even at a higher voltage than that being used at the time, would be a sure sign that the current had found a path offering less resistance than the dentin, and if this is not corrected the administration will prove a failure. It is wise to always test the polarity of the terminals before applying the current. This may be done by bringing the ends of the terminals together, when the switch of the rheostat is on the first or second point, or they may be tested with wet litmus-paj)er, or paper moistened with solution of potassium iodide, when the j)Ositive pole will give the charac- teristic reaction. It has already been stated that the positive pole produces coagulation of the albuminoid substances contained in the tissues, and this may result in the dentin if too strong a current is used. This no doubt has been another source of failure in electrococaine anaesthesia. The use of coagu- lating remedies like carbolic acid should never be allowed in a cavity when catai)horesis is to be employed, as coagulated albumin is not a good conductor of electricity, and hence the diffusion of the cocaine by the current would be greatly retarded. GENERAL ANESTHESIA. The employment of general ansBSthetics sometimes becomes necessary in the treatment of hypersensitive dentin, but they should be resorted to only in extreme cases, when all local means have failed, or when for some reason they cannot be employed. The general anaesthetics which have been used for this purpose are nitrous oxide, sulphuric ether, and chloroform. In the employment of these remedies for obtunding the hypersensitiveness of the dentin, the confidence and intelligent co-operation of the patient is a sine qua non, for the reason that a profound anaesthesia, or even loss of consciousness, is not necessary or even desirable if the best results are to be obtained from their employ- ment. During t\iQ first stage of anaesthesia, or just before the second, or stage of excitement, appears, sensation in the peripheral extremities of the nerves is greatly diminished or entirely obliterated, so that it becomes possible to make slight incisions in the skin or mucous membrane, or cut the most sensitive dentin without the slightest sensation of pain. During the first stage of anaesthesia the patient is drowsy and the mus- cles are relaxed, but conscious cerebration is not impaired. This is an im- portant consideration, for upon this fact rests the co-operation of the patient, and this is absolutely necessary if the operation is to be successfully per- formed. If the administration of the drug is continued to the develop- ment of the stage of excitement, the patient becomes unmanageable, and all delicate operative procedure is at an end ; while if profound anaesthesia is induced, the insensible condition of the patient renders that co-operation which is so desirable to the performance of such operations entirely out CATAPHOKESIS. 215 of the question. Furtliermore, the upright position of the patient is necessary to the performance of these operations, which adds greatly to the dangers surrounding general anaesthesia, especially when chloroform is used. If, upon the other hand, it becomes necessary to remove a vital pulp, nothing short of a profound state of anaesthesia will suffice for a painless operation. Nitrous Oxide. — The use of nitrous oxide as a means of producing partial ansesthesia for the relief of pain in operating upon hypersensitive dentin has often been advocated and successfully employed. In the use of this agent the assistant should stand by the side of the chair ready to turn the gas on or off as the needs of the case may require. It should then be explained to the patient that five or six deep inspira- tions will usually be sufficient to render the cutting of the dentin an entirely painless operation, but that this insensibility to pain will last only for two or three minutes, consequently it becomes necessary to operate very rapidly, and to this end the assistance and co-operation of the patient is earnestly solicited. Assurance should also be given that upon the slightest indication of a return of painful sensations the gas shall be again administered and this process repeated until the cavity has been prepared. AVith these explanations and assurances the confidence of the most timid patient will be secured and intelligent co-operation obtained. The inhaler (Fig. 322) should then be placed in the hands of the patient and instruction given in the method of applying it and of breathing. The gas is now turned on, and after five or six full inspirations have been taken, the inhaler may be removed and the sensitiveness of the dentin tested, and if it has disappeared, the exca- vation of the cavity may be proceded with, but if not, then three or four inspirations more may be taken, when the sensitivity of the dentin will be found to have been entirely overcome. As soon as the anaesthetic effect begins to pass off the inhala- tions should be renewed. Sulphuric ether is perhaps the most reliable general anaesthetic that can be employed for this purpose, as the obtunding effect upon peripheral sensation is more lasting than nitrous oxide, and far less dangerous than chloroform to the life of the patient. In administering ether care should be exercised in the selection of an inhaler to obtain one that will permit an abundant admixture of atmospheric air with the ether vapor, as by this precaution the irritation to the air-passages which is so common in Fig. 322. Flexible face-piece for inhalers. 216 OPERATIVE DENTISTRY. Fig. 32.3. Allis's ether inhaler, rubber covered. the early part of ether anaesthesia is entirely obviated. The Allis inhaler (Fig. 323) is constructed with this object in view, and is the best invention of its kind that is manufactured. The time required to produce peripheral anaesthe- sia is about two minutes, and it lasts fronl two to five minutes. When ether is to be employed for its anaesthetic effect, the patient should be cautioned against eating just before the operation, as under such circumstances nausea and vomiting might occur. It is safest to take only a light meal three or four hours before the operation and no stimulants. With these jjrecau- tions there need not be the slightest fear of any unpleasant symptoms attending or following the employment of ether for this purpose. Chloroform has been employed by some operators, while others have used the A. C. E. mixture, — alcohol one part, chloroform two parts, ether three parts. Chloroform and the A. C. E. mixture are not safe remedies to use for producing anaesthesia when the patient must be seated in an upright position, on account of the depressing effect of chloroform upon the action of the heart. Chloroform and its combinations are therefore contraindi- cated in all operations requiring the erect position as an essential feature of the procedure. Bon will Method of Rapid Breathing. — The late Dr. Bonwill advo- cated several years ago a system of rapid breathing as a means of pro- ducing peripheral anaesthesia. The system consists of making very rapid and full inspirations and expirations — as though one were running — and keeping this up until the head becomes dizzy, when it is found that peripheral sensation has been greatly obtunded, and in some cases as com- pletely obliterated for a brief period as though some anaesthetic drug had been administered. The writer has occasionally employed this method with very great satisfaction in the treatment of hypersensitive dentin, and in a few instances has also extracted teeth which the patients have de- clared was done without producing the slightest painful sensations. CHAPTER XV. THE CLASSIFICATION OF CAVITIES. Carious cavities in the human teeth are usually divided into two gen- eral classes, — viz., simple and compound. These have been again divided into three general classes, — viz., 1, simple cavities upon exposed surfaces ; 2, simple approximal cavities; 3, compound cavities. The Jirst division includes all of those cavities which are found upon the morsal, buccal, labial, and lingual surfaces of the teeth, which afford easy and direct approach to all parts of the cavity, and which are bounded by a continuous and unbroken wall of regular or irregular outline. The second division comprises all of those cavities which are located ui3on the approximal surfaces of the teeth, and are likewise bounded by a continuous and unbroken wall, but which do not, on account of their location, give ready and direct approach to all parts of the cavity, except, first, by separating the teeth, and secondly, by using instruments for their preparation which have been curved or bent at suitable angles. The third division is made up of all those cavities which are produced by a union of two or more cavities of the previous divisions, no matter whether they have been united by the extension of the process of caries or by surgical means. Weeks, in his '^ Manual of Operative Technics," offers the following classification of cavities : A. — Cavities arising from structural imper- ■ fections in pits and fissures. B. — Cavities on labial, buccal, or lingual surfaces, caused by contact with secretions from diseased tissues, or the products of fermentation. Class 1. All cavities on any surface other than proximate. (All cavities on the proximate surfaces of incisors and cuspids. A. — Cavities which do not involve the mesial or distal angle. B. — Cavities which involve the restoration of the mesial or distal angle. Class 3. All cavities on the proximate surfaces of bicuspids and ■ molars. f A. — Cavities which include the marginal ridge, but do not involve any sulci or grooves upon the occlusal surface. B. — Cavities which involve not only the marginal ridge, but also the sulci or grooves upon the occlusal surface. For the purposes of more accurately locating and describing each indi- vidual cavity, the following admirable division and classification has been taken from the "American Text-Book of Operative Dentistry," and slight changes made in it to give it a more comprehensive application. This 217 218 OPERATIVE DENTISTRY. classification is arranged progressively from the simplest form, A, to the most complex, W. The writer, however, takes the liberty of changing the terms occlusal and incisal, to morsal, as the latter term is equally applicable to both, and, as a multijDlication of terms is to be avoided, there can be no valid objec- tion to the change. I. Simple Cavities upon Exposed Surfaces. Incisors and Cuspids. Bicuspids and Molars. A. Labial D. Morsal. B. Lingual. E. Buccal. C. Morsal. F. Lingual. II. Simple Appeoximal Cavities. Incisors and Cuspids. G. Mesial. H. Distal. III. Compound Incisors and Cuspids. K. Mesio-labial. L. Disto-labial. M. Mesio-lingual. N. Disto-lingual. O. Mesio-morsal. P. Disto-morsal. Q. Mesio-disto-morsal. Bicuspids and Molars. I. Mesial. J. Distal. Cavities. Bicuspids and Molars. K. Mesio-morsal. S. Disto-morsal. T. Morso-buccal. U. Morso-lingual. V. Mesio-disto-morsal. W. Bucco-linguo-morsal. Adopting this arrangement and classification as the best, the writer will adhere to it in all future descriptions of the location of carious cavities and of fillings. I. SIMPLE CAVITIES UPON EXPOSED SURFACES. Incisors and Cuspids. A Class. — Cavities upon the lahial surface of the incisors and cuspids are usually found in two locations, — viz., at the cervix and near the morsal edge. Cavities at the cervix in the early stage of the carious process are generally in full view, and may consist of a softened condition of the enamel without visible loss of structure, or they may present any of the characteristics of the more advanced stages of the carious process. Fig. 324, A, A, shows the form and location of this class of cavities. Fig. 324. Fig. 325. Fig. 326 The preparation of those cavities which occur at the cervix offer no serious difficulties, unless they extend beneath the gum. Under such cir- cumstances it becomes necessary, in order to gain a good view of the THE CLASSIFICATION OF CAVITIES. 219 cavity and to properly prepare the cervical margin, to evert the overhang- ing gum. In the simpler cases this may be accomplished by pressing the gum away with a suitable instrument held in the left hand during the preparation of the cavity, care being exercised not to wound the gum, as the hemorrhage would obstruct the view. In the more complicated cases, where the edge of the gum has become inverted, it is necessary either to excise the inverted gum tissues or to evert them by packing the cavity over-full with gutta-percha and allowing it to remain for a few days. This procedure gives a clear field for the preparation of the cavity and the subsequent operation of filling. The adjustment of the rubber dam is sometimes a difficult procedure in these cases, but it can usually be ac- complished by exercising a due amount of patience. Absolute dryness of the cavity is imperatively demanded in a proper preparation, as well as for the subsequent operation of filling. Spoon excavators and round burs will be found to be the most useful instruments in the preparation of these cavities. Eetention may be obtained by slight uuder-cuts at the bottom of the cavity, at the cervical and morsal margins, and following its outline from one extremity to the other. Too much care cannot be expended in the preparation of the margins and terminal points of these cavities. They should be nicely bevelled, as shown in Fig. 325, and finished as smoothly as possible, so that the margin of the filling when finished will present a perfect outline. Cavities which occur upon the labial surface near the morsal edge are the result of developmental defects in the enamel in the form of pits and grooves, which cross the surface in nearly a straight line or surround or girdle the entire tooth at an equal distance from the morsal edge. This condition is shown in Fig. 326, A. These imperfections when quite shallow may be removed by corundum wheels and the surface polished. If, however, they are deep, it is better in the case of small pits to treat each one as a separate cavity, as illus- trated in Fig. 326, B, but when they are large, leaving but little tooth sub- stance between them, or in the case of deep grooves, it is better to convert them into a single cavity and fill it with gold, or set a porcelain inlay ; but when the groove girdles the tooth and is deep, the better plan for the sake of the cosmetic eifect would be to cut off the tip and replace it with porcelain. B Class. — The vulnerable ppint on the lingual surface of incisors and cuspids is the fossa formed by the union of the marginal and basilar ridges. This fossa is often deep and not infrequently presents a i3it or fissure in its deepest portion, which sometimes becomes the seat of caries, as shown in Fig. 327, A. As a rule, in the early stage of the disease these cavities are much deeper than they are broad. They are usually marked at the orifice by a dark spot, which often extends to a considerable depth, but rarely in- volves the pulp -chamber. In the preparation of these cavities in the incipient stage of the dis- ease the round bur is usually found to be the best instrument for the pur- pose. Retentive shaping is rarely necessary, as the depth of the cavity 220 OPERATIVE DENTISTRY. generally is greater than its diameter. The margins of the orifice, however, should be bevelled or countersunk, as in Fig. 327, B, by the use of a larger round bur, in order to insure perfect adaptation of the filling and to pre- vent bruising or fracturing of the enamel edge during the process of introducing the gold. In cavities presenting the later stages of the carious process, and which involve the greater i)ortion of the lingual surface of the tooth and com- plicated with an inflamed or devitalized pulp, anchorage may be secured by enlarging the pulp-canal, as shown in Fig. 328 ; the preparation should Fig. 328. Fig. 329. Fig. 330. After Dr. Marshall Webb. be conducted upon the same general principles as those adopted in the treatment of simple morsal cavities in the bicuspids and molars. C Glass. — Cavities occurring upon the morsal edge of the incisors and cuspids are very rare, except as the result of fractures of the enamel or from mechanical abrasion or attrition. Fig. 329 shows such cavities in the superior incisors. These cavities are usually quite shallow, and being easy of access, no difficulty is experienced in their preparation. Care, however, must be exercised in the preparation of the enamel mar- gins to extend the bevel to the marginal edge, so as to prevent future fracturing of the enamel. Failure in this direction often ruins an other- wise substantial and beautiful operation. Retentive shaping is also an important feature in this class of cavities. The strain is often very great upon such fillings, particularly in those cases where the teeth have been shortened by excessive mechanical abrasion and the normal length is to be restored ; consequently every efibrt should be made to give the filling the greatest security by proper reten- tive shaping. The drilling of retaining-pits is not to be recom- mended when the location and the extent of the cavity will permit it to be slightly enlarged at the bottom. This enlarge- ment should extend in all directions, giving a dovetail or, more correctly, an inverted-cone form to the cavity (Fig. 330). Caries sometimes occurs as a result of developmental defects in the enamel ; such cavities are to be prepared and filled like other cavi- ties of the same size and form. Bicuspids and Molars. D Class. — This class comprises all of those cavities which occur in the pits and fissures upon the morsal surface of the bicuspids and molars. Their location is such that an unobstructed view can be obtained of all parts of the cavity, and they are easily accessible to direct instrumentation. The difficulties in operating are somewhat increased in the posterior part THE CLASSIFICATION OF CAVITIES. 221 of the mouth, especially in the superior third molars, but with properly curved excavators, the right-angle hand-piece and reflected light, the preparation of such cavities becomes a comparatively simple matter. The loicer first bicuspid usually presents the simplest form of cavity upon the morsal surface of the teeth. The triangular ridge connecting the buccal with the lingual cusp is usually very large and prominent, and under" such circumstances the mesio-distal sulcus is not strongly marked or is wanting altogether. The triangular ridge forms with the mesial and distal marginal ridges the mesial and distal pits. These pits are usually the first part of the tooth to be attacked by caries. Caries attacking the pits form simple roundish, penetrating cavities, which may be opened and prepared separately with round burs. On the morsal surface of the upper first and second Mcuspids, caries usually begins in the fissure between the cusps (Fig. 331). It sometimes presents as a simple dark line, into which the sharp point of an explorer will hardly enter, while at a later period the cavity will have been increased in size t^- ^ >, , ^^' ' ' ^^ ■ -^ •^ Disto-buccal >**^^ , Mesio-buccal by the undermining of the enamel and fissure. \/^ A/^ fissure. the disintegration of its margins, so that jr^"^^i sulcus^ an excavator will readily pass through ^^'*°"''&t /-^^_^^ Me^o-iinguai the entire length of the fissure. These cavities in their earlier stages may be opened with the tapering fissure-burs ; in the later stage enamel- chisels will be found most useful. After the cavity has been opened, the decay should be thoroughly removed and a proper retentive shape given to it. Especial care should be given to the terminal pits and to the triangular grooves or fissures. The latter should be cut out to their fullest extent, or until all suspicious tissue has been removed. The margins should then be carefully bevelled and the cavity is ready for the filling (Fig. 332). The student should be cautioned against sacri- ficing more of the sound tissiie than is really necessary to gain the object in view. Whenever possible the mesial and distal marginal ridges should be maintained intact, as these bind the buccal and lingual cusps together, and if they are destroyed, the crown is greatly weakened and the cusps- are liable to be fractured and broken away. Sharp angles are to be avoided, especially in the outline of the cavity margins. All angles should be rounded out, and the outline of the cavity should present, when finished, a series of graceful curves. The morsal surface of the loicer second bicuspid usually presents three cusps, which are divided by the triangular groove, the termination of each arm of the groove ending in a pit. The most vulnerable points in this groove are at its centre, where the arms of the groove meet, and at the terminal pits. Caries occurring in any part of the groove will make it necessary to cut it out in all directions as the only way to insure the tooth against a recurrence of the disease in this location. Upon the morsal surface of the upper first and second molars there are two points at which caries is liable to occur, one known as the mesial fossa, the other as the distal fossa, and situated respectively upon the mesial 222 OPERATIVE DENTISTRY. and distal sides of the oblique ridge (Fig. 333). These fossae are sometimes traversed by a broad sulcus or a deep fissure. The fissure of the mesial fossa often assumes a triangular form. To insure success it is necessary to cut out the fissures to their utmost limits. The instruments used for pre- paring these cavities should depend upon the progress which has been made by the disease ; when limited in extent, small-pointed fissure-burs are the best for opening the cavity ; in the later stages the enamel-ehisels will be found most useful. The margins should be so prepared as to leave smooth, strong bevelled edges (Fig. 334). Occasionally the mesial and distal cavities will be found united beneath the oblique ridge. Under such circumstances the bridge between the orifices of the cavities should be cut away and the two cavities converted into one. Fig. 335 represents the prepared cavity. The mistake of Fig. 332. Fig. 333. Fig. 334. Fig 335. leaving the bridge of enamel and dentin between them is often made, even by good practitioners, but such oj)erations sooner or later come to grief, either from fracture during the operation of filling, or later from the stress of mastication. The morsal surface of the upper third molar is usually surmounted by only three cusps, and has, like the lower second bicuspid, a single central fossa and a triangular fissure radiating from the centre of the fossa and passing between the cusps. This cavity should be so prepared that when finished it will be triangular in form, with the points of the angles rounded out so that the filling- material may be perfectly adapted to the walls and margins. Fig. 336 represents the prepared cavity. Failure more often occurs in these cases than in any other of their class, for the reason that the fissures are not always cut out to their utmost limit and perfectly sound enamel and dentin reached in every part before the filling is introduced. There is also more difficulty experienced by the patient in keeping these teeth perfectly clean after the operation ; especial care should therefore be exercised to make the operation as nearly perfect as possible, so that no open point of attack may be teft for the entrance of the micro-organisms of decay. The morsal surface of the lower first and third molars each present five cusps,— three buccal and two lingual, — with sulci running between them. A cavity, therefore, occurring upon this surface and following the sulci w.ould present a five-pointed or pentagonal outline (Fig. 337). As a rule, chisels are the most serviceable in opening these cavities, the extremities of the fissures being followed with the pointed fissure-bur, and finished with larger round ones. In following the fissure it is better to go a little too far into the sound tissue than to fail to remove every particle of the decayed or softened dentin or enamel. Thoroughness in the preparation of a cavity never THE CLASSIFICATION OF CAVITIES. 223 gives a greater reward than in these teeth. Fig. 338 shows the finished cavity. The morsal surface of the lower second molar presents four cusps with cruciform sulci separating them. Caries is most often found at the point of meeting of the sulci (Fig. 339, A). In preparing a cavity of this character the sulci should be cut out to their extreme limits, the sharp angles at the intersection of the sulci Fig. 33;; Fig. 336. Disto-buccal fissure. Distal fissure. Mesio-buccal fissure. Mesial fissure. Fig. 338. Lingual fissure. rounded out, and the margins bevelled. Sharp angles, if left at the inter- section of sulci, are liable to be bruised and fractured during the introduc- tion of a gold filling ; these angles should therefore be properly rounded out, as shown in Fig. 339, B. Occasionally the morsal surface of the bicus- pids and molars will be so extensively decayed as to involve the cusps, making a large open cavity extending over the whole morsal surface of the tooth. In preparing such cavities the morsal edge of the cavity should be first ground down with corundum wheels until strong walls are reached. The decayed tooth -structure should then be removed, the cavity given a shape as shown in the illustration of the longitudinal section of a tooth Fig. 340. Fig. 341. Fig. 339. A B Longitudinal section. (Fig. 340), and the edges of the cavity nicely bevelled towards the cavity. Fig. 341 shows such a cavity prepared for the filling in a bicuspid tooth. When the pulp is involved, this should first be removed and the canals filled, as described in Chapter XXVII. The pulp-chamber in these cases may be utilized for additional anchorage. E Class. — This class includes all of those cavities which occur upon the buccal surface of the bicuspids and molars. Caries is rarely found upon the buccal surface of the bicuspids, except at the cervix. These cavities are usually long and narrow, and follow the line formed by the free margin of the gum, and often extend beneath it. They are usually half-moon shaped 224 OPERATIVE DENTISTRY. or elliptical in form, as shown in Fig. 342, A, and not infrequently in- volve the approximal surfaces by their lateral extension. The upper molars have nearly the same exemption from caries upon the buccal surface, cavities appearing most often at the cervix ; the third molar being more often affected than the others. The outlines of the cavi- ties formed at this point are similar to those occurring in the bicuspids. Cavities occurring upon the buccal surface which do not involve the cervix are usually long, narrow, and ellii)tical in form, the long axis having a mesio-distal direction, as shown in Fig. 343, A. Occasionally, however, cavities wall be found in the buccal groove, located well towards the cervix. In the lower molars this condition is much more frequently found, and the cavities are sometimes quite large, extending to and involving the morsal surface, forming a compound cavity. As the disease extends it frequently passes beneath the free margin of the gum, thus increasing the difficulties in preparing the cavity for the reception of the filling. These difficulties may be overcome by adopting those measures already described in the preparation of labial cavities in Fig. 342. Fig. 343. A B 'a B the incisors and cuspids. Round engine burs and spoon excavators are the most suitable instruments for preparing this class of cavities. The right-angle hand-piece will also be found very useful in preparing the cavities in the molars, particularly those located in the second and third molars. The retentive form given to them should be that of slight under- cuts at the base of the cavity, in a line parallel with its long axis ; but sometimes it is well to make slight retention pits in the mesial and distal extremities of the cavity. The angles should be rounded out and the mar- gins slightly bevelled, as shown in Fig. 342, B, and Fig. 343, B, in order that perfect adaptation of the filling- material may be secured. Simx)le cavities occurring in the buccal groove of the upper and lower molars should be prepared with a slightly under-cut form. The prepara- tion of those cavities which are compound in their nature will be described under T Class. F Class. — Caries rarely occurs upon the lingual surface of the bicuspids. The molars, however, present a slightly increased liability. Cavities upon the lingual surface of the ujyper and loiver molars occur in the lingual groove, at the cervix, and in the upper first molars in the fissure which exists be- tween the mesio-lingual cingule or fifth cusp, when this is present, and the crown. The degree of exemption from caries possessed by the lingual surface of the bicuspids and molars is doubtless due to their smooth and rounded THE CLASSIFICATIOX OF CAVITIES. 225 surfaces, tlie friction of the tongue in speech and mastication, and the more abundant presence of the oral secretions, which have a tendency to keep them clean. The most common location of caries upon .these surfaces is the Ungual groove of the upper first molar, which often presents a deep tissure termina- tion in a pit about midway between the linguo-morsal margin and the cervix. Caries usually appears first in the pit, and sooner or later extends through the entire length of the fissure, joassing over onto the morsal sur- face and forming a compound cavity. When the groove is shallow and not traversed by a fissure, the cavity is often confined to the terminal pit. Caries occurring at the cervical margins of the lingual surface of the bicuspids and molars are, from the difficulties presented by their location, often troublesome to properly prepare and fill. They should be prepared and filled after the same manner as those cavities occurring upon the buccal surfaces of the same teeth. Cavities occurring in the fissure between the mesio-lingual cingule and the crown should be opened through the entire length of the fissure as the only means of preventing extension or a recurrence of the disease. No especial description of the preparation is necessary in this class of cavities. They should be treated and filled according to general principles. II, SIMPLE APPROXIMATE CAVITIES. Incisors and Cuspids. G and S Classes. — The location at which caries most frequently occurs upon the approximal surfaces is not at the actual point of contact of these surfaces, but in a location a little nearer to the cervix, just beyond the point of the F formed by the intcrapproximal space, — in other words, just where fluid and semifluid debris would be held by capillary attraction. Another location of caries of the approximal surfaces is just at the margin of the gum where the festoon forms the base of the interapproximal space. Occasionally two such decayed spots will be found upon a mesial or distal proximate surface ; and it is a very common circumstance to find the ap- proximating surfaces of the teeth decayed in exactly the same locations. In the incisors and cuspids the carious spot is at first round in form, in the bicuspids oval, and in the molars it is oblong. (Jack.) In the later stages of the disease the cavities assume shapes more in accordance Fig. 344. ^^^j^ ^^^^ ^.^^^^^ ^^ ^^^ proximate surfaces of the tooth, — as, for instance, in the incisors and cuspids the cavities will be trian- gular in outline, the base of the triangle being towards the cervix, as shown in Fig. 344, while in the bicuspids and molars the form will be more nearly that of a rectangle. The mechanical difficulties presented in the treatment of simple proximate cavities of the anterior teeth are only those arising from their inaccessibility. In order to obtain an unobstructed view of the cavities, temporary separation of the teeth is a necessity. But sometimes, even after thorough separation, a good view of some parts of the cavity 15 226 OPERATIVE DENTISTRY. cannot be secured without cutting away a portion of either the lingual or the labial wall. The lingual wall, for the sake of the cosmetic effect, should be sacrificed in preference to the labial, as gold fillings upon the labial sur- faces are at the best blemishes which seriously mar the beauty of the natural tooth. On the other hand, if the cavity is large and the labial wall is much weakened, the success of the filling, and perhaps the salva- tion of the tooth, will depend upon the thoroughness with which this weakened wall is removed ; but, nevertheless, care should be exercised not to remove more than is necessary to obtain strong margins. Large cavities often come dangerously near to the pulp ; great careful- ness should therefore characterize the work of their preparation, that this organ may not be exposed by an unneccessary sacrifice of sound dentin. Small chisels will be found most useful in opening all simple proximal cavities, while small hatchet excavators having bayonet-shaped shanks, and cow-horn spoons, as shown in Figs. 345 and 346, will, as a rule, gain access Fig. 345. to all parts of the cavity and permit the ready removal of the decayed dentin. Bound burs of suitable sizes will be best adapted for trimming and shaping the cervical margin of the cavity, which should be so prepared as to leave a strong and but slightly under-cut or perfectly flat wall, care being taken, if the cavity reaches the cervix, not to leave a narrow rim of enamel which would be likely to be fractured in condensing the gold against it. The enamel margins should always be carefully bevelled with small chisels and polished with file-cut burs and Arkansas stones. All THE CLASSIFICATION OF CAVITIES, 227 Fig. 347. angles should be rounded with chisels, burs, or stones. Fig. 347 represents the prepared cavity. Eetentive shaping of these triangular-formed cavities requires that three points of anchorage be obtained, two at the base of the triangle in the angles and one at the apex. These may be formed by deepening the angles at the bottom of the cavity at the cervix with a small, round bur, and that in the apex at the morsal edge with a small hatchet excavator. Shallow undercuts may also be used as a means of retention in the smaller cavities. Retention grooves, however, should never be cut in the labial and lingual walls, as these weaken the walls to a serious extent. Cavities which extend beneath the gum should be treated beforehand by the removal of the overhanging gum tissue, so that a clear aad unob- structed view of the cervical margin may be obtained. Occasionally, either from the size or location of the cavity, it approaches very near to the morsal edge (Fig. 348, A), rendering the unsupported enamel very liable to fracture. Under such circumstances it is better to remove the weaktiorner and convert the cavity into a compound one, as illustrated in Fig. 348, B, rather than to attempt its conservation and have it break away at some future time under the stress of mastication. Fig. 348, A B Fig. 349. Black has suggested as a means of anchorage in these cases the exten- sion of the cavity upon the lingual surface in the form of a dove-tail, as shown in Fig, 349, A, rather than by forming a retaining pit or groove at the morsal edge of the tooth. Such an extension need not necessarily weaken the tooth to any appreciable degree if it is not formed too near the morsal edge or cut too deeply into the dentin, while it adds greatly to the retentive i)ower of the cavity at the point where the greatest strain comes in biting or during mastication. Bicuspids and Molars. I and J Glasses. — Small cavities upon the mesial and distal surfaces of the bicuspids and molars present considerable mechanical difficulty in their preparation. Figs. 350 and 351 illustrate cavities of this character. These difficulties, which are mainly those of inaccessibility, are greatest when the teeth maintain their normal approximation. They can, however, usually be overcome by making temporary separation, the space being made as wide as the circumstances of the case will permit. The wider the 228 OPERATIVE DENTISTRY, space obtained the greater will be the ease with which these cavities can be approached. Figs. 352 and 353 represent the prepared cavities. When ready access cannot be attained in this way, one of two other methods must be adopted, — either to convert them into compound cavities by cutting through the morsal surface until the cavity is reached, or by ex- tending the cavity to the buccal surface. The former of these two methods should receive the preference as being the least difficult to accomplish, and makes the strongest operation from the mechanical stand-point ; whereas in the latter method the difficulties are increased by reason of the limited amount of space in which to operate, while the overlying enamel at the morsal surface of the api)roximo-buccal angle will always remain an element of weakness as a result of its being undermined in extending the cavity to the buccal surface. Sometimes, however, this is the only method by which the cavity can be reached. Simple cavities upon the approximal surfaces of the bicuspids and molars more often fail after being filled than any other class of cavities. This is no doubt largely due to the fact that operations in these locations do not permit of ready access to all parts of the cavity, and cannot therefore be so thoroughly and perfectly prepared as those in which these difficulties do not have to be ov^come. Fig. 350. Fig. 351. Fig. 352. Fig. 353. In the opening of these cavities small, straight, and acute-angle chisels will be found very useful, while the removal of the decay and the prepara- tion of the margins can best be accomplished with round burs in the straight or right-angle hand-piece, according to the mesial or distal loca- tion of the cavity. Distal cavities are the most difficult to reach with instruments, and the only view that can be obtained of them is by reflection in the mouth mirror. This naturally adds to the difficulty in preparation and filling. Eetentive form may be given to the cavity by slightly enlarging it at its base, or undercutting at two opposite points. This may be accom- plished with small hoe excavators of obtuse and acute angles and small hatchets. In preparing and finishing the enamel margins, advantage can be taken of the natural outward i^adiation of the enamel- prisms to give the proper bevel to the orifice of the cavity. In large cavities upon the approximal surfaces which approach the morsal surface it is best to cut through this surface and convert it into a compound cavity, rather than to run the risk of fracture of the enamel at a later period and consequent loss of the filling. THE CLASSIFICATION OF CAVITIES. 229 III. COMPOUND CAVITIES. Incisors and Cuspids. K and L Glasses. — Compound cavities are formed by the union of two or more simple cavities located upon diiferent surfaces of a tooth. The simpler class of compound cavities are those located upon the mesio-labial and disto- labial surfaces. Fig. 354 shows such cavities in the superior incisors. Teeth thus affected are generally of faulty organization and are markedly predisposed to caries. Such cavities are usually formed by the joining of an approximal cavity with one at the cervical margin of the labial sur- face. Sometimes the cavities will be separated by a narrow isthmus of more or less infected enamel or perhaps of sound tissue. In either case the cavities should be connected, the isthmus cut away, and the enamel edges straightened before the margins are finally finished for the filling. Acute angles, uneven marginal lines or peculiarities in form, are to be avoided in all operations that occupy a consi3icuous position in the ante- rior part of the mouth, for the reason that things peculiar attract the attention much more quickly than those which follow the general order. Temporary separations are commonly necessary in order to gain access to that portion of the cavity which is located upon the proximal surface. Fig. 354. Fig. 355. Fig. 356. Fig. 357. In the preparation of these cavities especial pains should be taken with the enamel margins, particularly at the cervical border and at the angle formed by the union of the cavities, as these are the points at which fail- ures most frequently occur in this class of fillings. Eetention may be secured by grooves cut in the walls at the base of the cavity, and by a single shallow retaining pit at each extremity of the cavity to assist in starting the filling. Fig. 355 shows such cavities pre- pared. Separate descriptions for the preparation of these two classes of cavities are not necessary, as one does not possess a peculiarity which is not com- mon to the other, except that of location, and this does not materially affect the method or the difficulties of the operation. MandN Glasses. — Compound cavities of these classes are located upon the mesio-lingual and disto-Ungual surfaces of the incisors and cuspids. These cavities are usually formed by the union of a proximate cavity with one occurring in the basilar pit or sulcus connected with it, as illustrated in Fig. 356. Such cavities are most often found in the central and lateral incisors, and from their location and the relative inaccessibility offer con- siderable more difficulty in their preparation and filling than those involv- ing the mesio-labial or disto-labial surfaces. Fig. 357 represents the pre- pared cavity. When two simple cavities exist upon the proximate and lingual surfaces of these teeth which nearly approach each other, it is better 230 OPERATIVE DENTISTRY. to join them as in the manner described in K and L Classes, rather than to fill them as separate cavities with only a narrow isthmus of healthy den- tal tissue between them, for sooner or later this tissue will be attacked by caries and the whole oj)eration prove a disastrous failure. Eetention is best gained by undercutting the lingual cavity and slightly grooving the cervical wall. Grooves in the labial or lingual walls of the cavity are not admissible, as they weaken these walls and increase the dangers from fracture. Occasionally it becomes necessary to connect a mesial and distal cavity with one upon the lingual surface. This is to be avoided whenever possible, for the reason that when both of the marginal ridges have been destroyed the crown of the tooth has lost its strongest support, and is very liable to be fractured whenever a severe strain comes upon the lingual surface near the morsal edge. O and P Glasses. — Cavities of these classes are generally confined to the incisor- teeth, and are formed by a union of a mesial or distal cavity with one upon the morsal edge. They do not, as a rule, appear until after middle life, the morsal cavity being produced by attrition and gradually deepening until it becomes connected with a proximate cavity produced by decay. Occasionally through accident a mesio- morsal or disto-morsal angle of a tooth is lost (Fig. 358), necessitating the formation of a cavity Fig. 358. Fig. 359. Fig. 360. involving both the proximate surface and the morsal edge before restora- tion of the lost part with gold can be undertaken. The preparation of these cavities involves no principle which has not already been emphasized. Each cavity may be prepared separately, after the manner already described, but especial care should be exercised in the preparation of the angle formed by the junction of the two cavities. The labial portion should be cut away just as little as is compatible with strength and the removal of unsound tissue. The lingual wall, which is more liable to be fractured by stress of mastication, may be removed more freely and its contour restored by the filling. The enamel margins of the morsal portion of the cavity should be so bevelled that when the filling is inserted they will be protected by the gold from the dangers of fracture. When the enamel plates are very thin, they should be shortened and the normal length of the tooth restored with gold. The- necessary retentive shaping may be obtained by slightly under- cutting the morsal cavity and grooving the cervical wall of the proximate cavity. Additional retention may be secured by forming shallow retain- ing pits at the opposite ends of the groove at the cervical wall. In certain cases it may become necessary, in order to obtain firm anchor- age for such fillings, to form an extension-arm, as shown in Fig. 359, A^ or by giving the extension a curved or hooked form. These are ingenious THE CLASSIFICATION OF CAVITIES. 231 methods of retention, and afford a means of anchorage, which in many- cases, on account of the thinness of the tooth, could not be secured so well in any other way. Q Class. — Cavities belonging to this class are formed by the union of mesial, distal, and morsal cavities in the incisors and cuspids, as shown in Fig. 360. They differ from O and P Classes principally in extent, but the peculiarity of the form of the combined cavities makes their prepara- tion and subsequent filling an operation requiring the greatest care and skill. The methods of preparation and the securing of anchorage are in nowise different from those employed in the preceding class of cavities, but the exercise of a trained judgment is nowhere of greater value or more severely taxed than in the proper preparation and filling of these cavities. A thin or checked enamel wall, a deep undercut, an acute angle, or a rough or improperly bevelled margin are sufficient to cause the failure of a-n otherwise perfect operation. Bicuspids and Molars. B and S Glasses. — These classes comprise all of those cavities in the bi- cuspids and molars which are formed by a union of mesial or distal with morsal cavities of decay, and represent classes which are the most common and in many ways the most difficult to successfully fill. Fig. 361 illus- trates this class of cavities. Failures are common, after a few years, in this class of operations, even in the hands of the very best operators ; therefore it cannot be entirely the result of faulty manipulation, as some writers would have the profession believe. The vulnerable points in fill- ings of this class are the cervical margin, and "that margin which is nearest to the operator during the process of the introduction of the gold." (Johnson.) These are the points also which clinical experience teaches are most often the seat of secondary caries, and they are no doubt in many instances caused by imijerfect preparation of the cavity, faulty adaptation of the gold to ihe cavity walls, or lack of proper restoration of the inter- proximal space by adequate contouring. Fig. 361. Fig. 362. Fig. 363. There are, however, other factors entering into the causation of sec- ondary caries as impoi'tant as those just mentioned, — viz., the character of the tooth-structure, the natural shape of the approximal surfaces, the hygienic condition of the mouth, the state of the general health, the char- acter of the secretions, and the activity of the zymogenic organisms of decay. While these conditions are operative in all parts of the mouth, the latter are, nevertheless, more active in some locations than in others. 232 OPERATIVE DENTISTRY. Therefore, on account of the greater difficulties presented in keeping the approximal surfaces of the bicuspids and molars free from food debris, recurrence of caries is by that much more liable to occur in these loca- tions. Ordinary cavities in these locations present no serious difficulties either in their preparation or filling. Such fillings, however, are subjected to great mechanical strain during mastication, and therefore require to be very firmly anchored. Retention may be secured by a shallow groove at the cervical margin with shallow pits at each extremity of the groove, and giving a dove-tail form to the morsal portion of the cavity, as shown in Figs. 361 and 362. In molars having mesio-morsal or disto-morsal cavities firm anchorage may be secured by extending the buccal or lingual fissures, as shown in Fig. 363. Large cavities, however, which extend beneath the margin of the gum, and have involved portions of the buccal, lingual, or morsal surfaces, often present difficulties which require a very high order of mechanical knowl- edge and of manipulative skill to successfully overcome. In the preparation of all approximal cavities temporary separations are imperatively demanded, and these should be as wide as the surround- ing conditions will permit. The gum, if it overhangs the cervical margin, should be previously forced out of the way with gutta-percha or cotton. After the cavity has been roughly prepared, the rubber dam should be adjusted and the final preparation completed. The greatest care should be exercised to obtain strong walls, rounded angles, nicely finished margins, and firm anchorage. T Class. — This class of cavities is formed by a union of morsal with huceal cavities of decay, as shown in Fig. 364, and are more frequently found in the lower molars than in the upper. They have their origin in the x)it and developmental groove of the buccal surface and Fig. 364. in the fissures of the morsal surface. These cavities are often found united at their bases while still separate at their orifices. To insure a satisfactory result in filling such cavities it be- comes necessary to unite them by cutting away the bridge of tissue which connects their orifices. To attempt to conserve this bridge of tissue, which would be more or less infected, and the enamel without the proper support of sound dentin, would only invite failure of the operation by the danger from fracture during the introduction of the filling, or later under the stress of force applied in mastication. In those cases in which the bases of the cavities have not been united by the carious process, but in which union has taken place at their orifices by extension of the disease along the buccal groove, care should be exercised not to cut away more of the sound tissue than is necessary to give proper retentive shape to the cavity, in order that the tooth may not be unnecessarily weakened. Strong walls and well bevelled margins are nowhere more imperatively demanded than in this class of cavities, as the strain upon these teeth during mastication is often very great. THE CLASSIFICATION OF CAVITIES. 233 TJ Glass. — Cavities of this class are formed by a union of a morsal with a lingual cavity of decay. They are very rare except in the first and second upper molars. They have their origin in the pit and lingual groove which separates the mesio-lingual and disto- lingual lobes, and a cavity in a fissure of the morsal surface (Fig. 365). As a rule, these cavities do not involve the lingual surface of the crown to the same extent that the buccal sur- face is involved in the preceding class. Sometimes the cavity upon the morsal surface extends but very slightly upon the lingual surface, while at others it extends deeply towards the cervix. When the cavity upon the lingual surface is large, the disto- lingual cusp is liable to be much weakened by being undermined. Under such circumstances the cusp had better be cut away and the occlusion restored by contouring. The same general princij)les govern the prepara- tion of these cavities as in the preceding class. V Class. — Cavities which belong to this class are formed by the union of mesial, distal, and morsal cavities in bicuspids and molars, as illustrated in Fig. 366. The size of the combined cavities is often very large, and in those cases in which either or both the buccal and lingual walls are weak, it is better practice to restore the usefulness of the tooth by inserting a suitable artificial crown than by the introduction of a filling which in a few years would, in all probability, be lost from fracture of one of the two remaining walls of the tooth. Under favorable conditions, in cases where the walls are strong, a properly inserted filling would be the best means of restoring the usefulness of the tooth. I^o especial difficulties surround the preparation of this class of cavities other than those which arise from their size. The method of preparation is the same substantially as that described for E and S Classes. W Class. — Cavities of this class are somewhat rare and are formed by a union of buccal, lingmd, and morsal cavities, usually in the lower molars. These cavities do not present as great difficulties in their preparation and filling as many of those which have been already considered. The same general principle should govern their j)reparation and filling as are indi- cated for T Class. Fig. 366. CHAPTEE XYL PEEPARATION OF CAVITIES. THE^rs^ important element in the treatment of carious teeth by filling is the proper preparation of the cavity for the reception of the material which has been selected for the purpose ; the second is the introduction of the filling-material in such a manner as to hermetically seal the cavity ; and the third, to so finish the filling as to leave perfect margins and a highly finished surface. If these three conditions are successfully obtained, the operator has fulfilled his obligation to his client, and if failure follows, it will be due to conditions of health and local environments over which he has no direct control. Guilford says, "As many fillings fail from lack of thoroughness in the preparation of the cavity as from any other cause." Ottolengui asserts, '^When a cavity is filled scientifically the tooth is safer than ever, because the vulnerable point is now occupied by a ma- terial which will resist destruction by caries. If decay occurs along mar- gins, it is because those margins were improperly made, either as to shape or position, or else because the filling was unskilfully inserted or finished." Black also lays great stress upon the proper preparation of the cavity, and enunciated the broad principle of extension for prevention. He says, ''A large proportion of decays occur in the proximate sur- faces of the teeth, and for many years it has been noted that recurrence of decay after filling is especially liable to occur in these surfaces. A reason for this has generally been sought in some fault in the management of the enamel margins. The enamel margins about a filling should always be regarded as a weak point, and should be guarded in every possible way against the danger of a recurrence of decay. One great difficulty has been that the same rule of extension for prevention has not been applied to the proximate surfaces as has obtained in the grinding surfaces. Exten- sion for prevention is extension of the enamel margin from a line of greater liability to caries to a line of lesser liahility. Or, to change the phrase, it is to cut the enamel margins from lines that are not self-cleansing to lines that are self- cleansing." Parreidt says, ' ' One step is as important as the other. The slightest defect in either makes the result entirely questionable. Thoroughness and especially care are most important essentials expected of an operator who undertakes filling of teeth." Tomes, in speaking of the importance of a proper preparation of the cavity, says, "Upon the proper performance of this the ultimate success of the operation will, in great measure, depend." 234 PREPARATION OF CAVITIES. 235 Statements of this character, which are based upon practical expe- rience, might be multiplied almost indefinitely, but a sufficient number have been cited to indicate that there is but one opinion held upon the subject by the best authorities. The student, therefore, will be wise if at the very ontset of his profes- sional career he determines to profit by the exijerience of those who have learned — perhaps by a long series of failures — that the proper preparation of the cavity is as essential in the filling of a tooth as are proper founda- tions in the building of a house. "With solid foundations to build upon, the superstructure may be reared with the certainty that when the stress comes it will stand the test. In the preparation of a carious cavity for the reception of a filling each step in the operation should be thoroughly and conscientiously per- formed, so that when it is completed all infected tissue will have been removed and the cavity be in the best possible condition for the reception and retention of the filling. The general principles involved in the preparation of cavities are naturally divided into four progressive stages : 1. Opening the cavity. 2. Removing the decay 3. Retentive shaping. 4. Forming cavity margins. Opening the Cavity. — The first step in the preparation of all cavities is to freely ox:)en the orifice by cutting away all overhanging edges of enamel, so that wherever possible the walls may be readily approached from all points. Perhaps the most important step in the preparation of carious cavities is to cut away all overhanging enamel margins which are not supported by sound dentin, for they are always a source of failure. The only exceptions to this rule are perhaps a certain few cases where the enamel is not subjected to severe or direct strain ; as, for instance, in proximal cavities in front teeth in which, for cosmetic reasons, it seems advisable to conserve the enamel of a thin labial wall. The brittle character of the enamel, however, ren- ders it liable to be fractured whenever direct strain comes upon it, unless it is supported by something to counteract the strain. Its most natural sui^port is the dentin, but occasionally in such instances as those just mentioned artificial support in the form of oxyphosphate cement may be given to it before the introduction of a gold filling. The student is warned, however, against attempting to apply this method of support in any other class of cases, as failure is more than likely to follow all such attempts from the severe strain brought upon the teeth during mastication. Dr. Black, in his "Investigation of the Physical Character of the Human Teeth, etc.," demonstrated in the most positive manner, by elabo- rate and painstaking experiments, that many of the popular theories among dental practitioners in reference to the density of tooth-structure in early adult and advanced life, and their relative strength at these periods, were in many respects fallacious. The following table gives a general summary of the result of his investigations upon these points : 236 OPERATIVE DENTISTRY. General Summary op Results. No. of Cases. Average Age. No. of Teeth. Specific Gravity. Per cent, of Water. Per cent, of Lime Salts. Per cent, of Organic Matter. Average for total number of teeth The highest percentage The lowest percentage Greatest variation Ill 32.33 268 2.092 2.133 2.036 0.097 11.06 13.56 9..32 4.24 63.54 65.75 61.08 4.67 25.36 27.59 23.26 4.33 Average for persons under 15 years old Average for persons 15 years old 11 8 20 15 26 12 10 10 11.00 17.00 21.55 25.93 33.00 42.66 53.00 63.60 13 9 48 43 72 38 19 27 2.066 2.080 2.081 2.086 2.092 2.094 2.105 2.019 11.89 11.46 11.47 11.27 10.84 10.91 10.85 10.66 62.26 63.18 63.43 63.44 63.42 63.73 63.83 64.56 25.92 25.33 Average for persons 20 years old 25.23 Average for persons 25 years old 25.28 Average for persons 30 years old 25.66 Average for persons 40 years old 25.34 25.29 Average for persons 60 years old 24.81 Average for males 20 years old 12 26 12 14 6 6 24 67 18 54 19 19 2.082 2.0S3 2.090 2.094 2.093 2.094 63.30 63.51 63.35 63.48 63.54 63.92 Average for females 20 years old Average for males 30 years old and under 40 Average for females 30 years old Average for males 40 years old Average for females 40 years old 0.043 ' 1.29 2.30 1.12 Average for persons who lost their teeth from diseases of the peridental membranes 15 50.00 51 2.101 10.88 62.90 25.19 Average for cases in which the teeth are classed as bad. Average for cases in which the teeth are classed as good Average for cases in which the teeth are classed as fair Average for perfect teeth Average for carious teetli 32 63 16 42 91 28.00 33.53 36.19 36.26 31.50 121 105 42 103 165 2.087 2.090 2.090 2.095 2.091 11.25 11.16 10.95 11.03 11.06 63.33 63.53 63.56 63.59 62.50 25.49 25.31 25.48 25.36 25.36 It has been generally believed that the teeth were very soft in child- hood and increased in density to old age ; that the teeth increased in strength from childhood to middle life ; that the strength of the teeth de- pended upon their density, and that the density of the teeth, or the per- centage of lime-salts which the tissues contained, was a controlling factor in the liability to caries. From the facts developed in this investigation the following conclu- sions are drawn by Dr. Black : (1) "The teeth are strongest in youth and early adult age, diminishing somewhat in strength with advancing age." This was ascertained first for the dentin by applying the stress to cubes eight-hundredths of an inch square cut from the dentin of permanent PEEPAEATION OF CAVITIES. 237 Exhibit of Elasticity and Crushing Stresses of Blocks of Dentin Eight-Hundredths OF AN Inch Square. Arranged according to the Age of Persons. Case. Age. Tooth. Carious or Perfect. Pulp Living or Dead. Specific Gravity. Per cent, of Lime- Salts. TO 1^ IS be . bCtn 246 9 /F c 1 2.069 62.83 1.5 3 285 212 10 F/ c 1 2.064 61.77 3 5 235 211 11 IF c d 2.061 2 4 247 207 12 IF c 1 2.073 62.40' 2 3 240 245 12 IF c 1 2.068 62.4'2 1.5 3 235 248 188 16 F/ c 1 2.067 61.71 2 4 275 218 16 6/ c d 2.078 62.83 2 3.5 225 244 16 IF c d 2.080 63.59 2 5 210 208 18 - /F c 1 2.080 63.65 3 5 210 230 210 22 H/ c 1 2.054 1.5 3.5 302.5 222 22 /4 c 1 2.098 63.80 2.5 4.5 235 229 22 /5 c 1 2.105 3 4.5 245 221 23 /F c 1 1.100 64.39 2 3 270 223 23 6/ c 1 2.085 63.32 3 5 220 /6 c d 2.067 63.27 2 4 235 /4 c 1 2.079 62.72 2 4 270 228>^ 24 /H c 1 2.068 2.5 4.5 245 173 25 /7 /8 /G c c c 1 1 1 2.110 2.131 2.095 260 216 275 213 25 F/ c 1 2.080 eii.bi' 2" 4" 280 216 26 /6 c 1 2.099 63.31 2 3 235 200 27 H/ p 1 2.098 64.77 2 4 270 247 27 6/ c 1 2.104 64.79 1 2.5 285 200 28 IS c 1 2.070 63.19 1.5 3 300 8/ c d 2.043 62.01 2 4 260 260 194 30 IF c d 2.101 63.71 2 4 250 215 31 (E c 1 2.126 2.5 4 245 /F c d 2.117 2.5 4.5 230 196 35 6/ c 1 2.096 64.ii" 2 4 2.50 198 35 8/ c 1 2.123 64.77 2 4 255 203 35 8/ c d 2.082 63.31 2 4 225 230 35 /5 p I 2.102 63.39 3 4.5 265 3/ p 1 2.074 63,27 2.5 4.5 245 /7 p 1 2.097 64.63 2 4 252 7/ p 1 2.087 63.94 3 5 250 217 36 7/ c 1 2.108 63.77 5 8 200 242 202 40 /F p 1 2.072 63.99 2 4 225 228 42 /H c 1 2.101 3 5 262 IE c d 2.108 64.06 3 7 200 192 44 4/ p 1 2.096 63.97 2 4 240 /4 c 1 2.108 63.74 3 6 250 /6 c 1 2.068 62.05 2.5 5 250 7/ p 1 2.111 64.51 2 4 265 /7 p 1 2.098 64.26 2.5 5 220 175 45 /3 /8 8/ c c p d d 1 2.078 2.099 2.085 183 178 225 231 47 F/ c d 2.103 64.13 3" 4.5 200 227 49 G/ c 1 2.105 64.53 3 5 220 224 193 50 6/ p 1 2.109 64.66 2.5 5 220 174 51 8/ p 1 2.123 207 250 51 /6 c 1 2.103 64.29 1.5 '3 ' 235 209 58 7/ p I 2.100 63.61 2 4 215 219 214 60 IF c d 2.106 64.68 2 4 230 233 60 /3 p 1 2.091 63.78 2 4 200 3/ p 1 2.095 63.84 2 4 215 /4 p 1 2.088 62.95 1.5 3 210 4; p 1 2.096 63.22 2.5 4.5 220 5/ p 1 2.059 62.25 2.5 5 195 6/ p 1 2.086 63.59 2 4 200 /6 p d 2.093 63.62 1.5 3 260 /7 p 1 2.109 63.94 2.5 4.5 250 7/ p 1 2.097 63.59 1.5 3 2.50 234 60 6/ p 1 2.122 64.. 57 1 2.5 290 195 61 3/ p 1 2.118 63.07 2 5 260 8/ p 1 2.112 64.16 2 4 235 /8 c d 2.113 64.16 3 6 225 226. 63 /6 c 1 2.104 68.24 8 1.2 185 232 65 /8 c 1 2.119 64.10 2 3 215 227 Average . . . 2.09 4.3 238 Number . . . 44 70 238 OPEEATIVE DENTISTRY. teeth of all ages. The instrument for applying and recording the amount of stress used was especially made for this purpose. The specific gravity of the dentin in all the specimens was ascertained, and the percentage of lime-salts also was obtained in nearly all, as well as the age of the individual furnishing the specimen, the particular tooth, whether sound or carious, the condition of the pulp, whether vital or dead, and all made a matter of record, together with the elasticity of the dentin under stress at one hundred pounds to the square inch, at one hundred and fifty pounds, and the number of pounds at which the block of dentin crushed. A reference to the foregoing table of results will show the figures in detail. It appears from this exhibit that the average crushing stress of dentin between the ages of nine and twelve inclusive is two hundred and forty-eight pounds to the square inch ; between the ages of sixteen and eighteen inclusive, two hundred and thirty pounds ; between twenty-two and twenty-eight years of age, two hundred and sixty pounds ; between thirty and thirty-six years, two hundred and foi'ty-two pounds ; between forty and forty-nine years, two hundred and twenty-four iDOunds ; between fifty and fifty-eight years, two hundred and nineteen pounds ; between sixty and sixty-five years, two hundred and twenty -seven x^ounds. The total average crushing stress was two hundred and thirty-eight pounds. In the table of ' ' General Summary of Eesults' ' the average specific gravity of the teeth at eleven years was found to be 2.066, while the average at the age of sixty-three was 2.019, giving a difference of forty- seven- thousandths of a volume. The increase in the amount of lime-salts follows the same rule. Be- ginning with 62.26 per cent, as the average at eleven years of age, it is increased to 64.56 per cent, as the average at sixty-three years of age, an increase of 2.3 i)er cent. The enamel was found to be very frail, the enamel-rods chipping off under very slight stress. The blocks of enamel, which were the same size as the blocks of dentin, except that they were only four-hundredths thick (8 x 8 x 4), crushed under a stress of from thirty to seventy-five pounds to the square inch. This emphasizes the need of the greatest care being exercised in the preparation of the enamel margins to prevent their being injured after the filling has been inserted, by the stress of mastication. A study of the force of the jaws in mastication, which was first under- taken by Patrick and Dennis in 1893, developed the interesting fact that the stress exerted by the jaws in biting was very much greater than had been supposed. Black discovered that there was a very great difference in the stress exerted by different individuals, ranging in adults from one hundred and twenty to two hundred and seventy pounds and more. The following table gives the results of tests of fifty persons, ranging from four and one-half years of age to forty-five years : PREPARATION OF CAVITIES. 239 Gnathodynamometer Records. No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 2-t 25 26 27 28 29 30 81 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 Occupation. Farmer Railroad passenger agent Railroad man Butcher Bookkeeper Miss, seven years old Servant-girl Teacher Dentist Grocer School-girl Laborer Physician Salesman Music-teacher School -girl Temporary molars Merchant Music teacher, on bridge On temporary molars Farmer Watchman Artist School-girl Chinese laundryman Grocer Athlete Butcher Lawyer Blacksmith Machinist Banker Bank clerk Dentist Grocer Farmer Temporary molars School-girl Physician Printer School -girl Student School -girl Physician Dentist Athlete Sex. Age. Height. Weight. Incisors. M 25 5-5 127 55 M 6 203 100 M 5-7 128 M 5-9 1.55 160 F 5-3 112 40 F 5-5 90 85 F 7 3-4 56 30 F 23 5-2 98 45 M 45 5-2 140 100 M 38 5-6 165 175 F 30 5-2 130 M 28 5-9 140 85 F 18 5-2 117 75 M 40 5-9 190 100 M 31 5-6 180 75 M 22 5-7 140 80 F 25 5-6 no 65 F 18 5-6 110 50 F 24 5-4 130 90 M 8 M 30 .5-10 140 45 F 35 5-5 120 M 8 M 26 6-3 200 60 M 25 5-8 1.50 100 F 35 5 110 45 F 19 5-11 123 60 F 24 5 110 45 M 5-4 140 50 M 5-10 204 1.30 M 6 230 70 M 30 5-5 176 140 M 5-9 164 65 M 45 5-8 195 45 M 40 5-3 130 80 M 35 6 148 30 M 5-5 130 60 M 35 5-8 220 45 M 5-8 1.50 80 M 6 170 90 M 4 k; 40 F 100 70 M 35 5-11 205 M 32 5-6 105 F 19 5-5 120 M 18 5-8 130 70 F 5-4 102 50 M 32 5-7 1.35 M 40 5-5 120 60 M 5-7 150 120 Bicus- pids. 1,30 185 Molars 125 210 150 130 125 65 100 140 240 155 160 150 180 1.30 135 120 75 160 65 155 145 45 145 160 65 135 60 165 170 160 165 160 140 160 70 85 160 160 190 45 120 270 70 100 120 100 165 The application of these facts to the strength of the dental tissues, and to the effect npon fillings and their anchorage, will result in more careful preparation of the enamel margins and more substantial anchorage of fillings. The instruments invented by Patrick and Dennis for measuring the strength of the jaws, and later perfected by Dr. Black, is known as the ' ' Gnathodynamometer." (2) ^' Teeth that have lost their pulps and have become discolored lose strength in a marked degree, apparently from a deterioration of the organic matrix." Tests were made of the strength of fifteen pulpless and discolored teeth from persons ranging from twenty-five to fifty years of age, all of which succumbed to stresses between one hundred and thirty to two hundred pounds. (3) '■ '■ Teeth that have become badly worn from mastication and in ■which the pulps had become so calcified as to cut off the nutrition of the crown 240 OPERATIVE DENTISTRY. portion of the dentin, lose strength apparently from deterioration of the organic matrix." (4) ^ ^ Teeth of old people, and especially those in which much calcifi- cation of the pulp occurs, deteriorate in strength." (5) "There is no basis for the supposition that the teeth of children, under the age of twelve years, are too soft to receive metallic fillings." (6) ''Differences in density, or in the percentage of lime-salts in the teeth, is not the controlling factor in the strength of the teeth nor of their hardness, this seeming to depend upon the condition of the organic matrix." (7) ''Differences in the strength of the teeth have no influence as to their liability to caries. Differences in density or in the percentage of lime-salts in the teeth have no influence as to their liability to caries." (8) " The active causes of caries is a thing apart from the teeth them- selves, acting upon them from without, and from a consideration of the facts thus far developed, the logical inference is that the cause of the differ- ences in the liability of individuals to caries of the teeth is something in the constitution, operating through the oral fluids, and acting upon the exciting causes of caries, hindering or intensifying its effects.''^ (9) "Caries of the teeth is not dependent upon any condition of the tissues of the teeth, but on conditions of their environment." (10) "Imperfections of the teeth, such as pits, fissures, rough or un- even surfaces, and bad forms of interproximate contact, are causes of caries only in the sense of giving greater opportunity for the action of the causes that induce caries.^'' (11) "The objects to be attained in filling teeth are the perfect exclu- sion of the causes of caries from the tissues by sealing the cavity, and securing such form as tcill prevent lodgement of debris about the margins of the filling, and thus prevent the further action of the causes of caries." (12) " There is no basis for the supposition that some teeth are too soft or too poorly calcified to bear filling with gold or other metal in use for that purpose, since all are found to be abundantly strong." (13) "There is no basis for the selection and adaptation of filling- materials to soft teeth, hard teeth, frail teeth (in structure), or poorly calcified teeth. What basis there may be in the conditions surrounding the teeth for the selection and adaptation of filling-materials must be left to future development to discover." (14) " With our present knowledge the only basis for the selection and adaptation of filling-materials to classes of cases is the individual opera- tor's judgment, as to which he can so manipulate as to make the most per- fect filling, considering the circumstances (environment), his own skill, and the durability of materials." (15) "There is no basis for the supposition that calcic inflammation of the peridental membrane, or phagedenic pericementitis (so-called pyorrhoea), attacks persons who have dense teeth in preference to those whose teeth are less dense." (16) ' ' There is no basis for the treatment of pregnant women medici- nally with the view of furnishing lime-salts to prevent the softening of PREPARATION OF CAVITIES. 241 Fig. 367. Water-syringe (reduced). their teeth, or with the view of producing better calcified teeth in their offspring." PREPARATION FOR OPENING THE CAVITY. . Many operators are in the habit of applying the rubber dam in all cases before commencing the operation of cavity preparation. The writer prefers to clear the cavity of the thin overhanging enamel edges, food debris, and the most softened portions of the dentin before applying the dam, as this gives opportunity for frequent use of the syringe (Fig. 367) and warm water charged with antiseptics or alkaline solutions, which often very materially adds to the comfort of the patient, and not a little to the sense of cleanliness, as well as relieving the patient for a portion of the time of what is to many the disagreeable pres- ence of the rubber dam. Absolute dryness, however, is always necessary in the final preparation of the cavity, as the exclusion of moisture makes it more easy to locate slightly discolored and decalcified dentin. The selection of the instruments with which to open the orifice of a cavity will depend upon its location, size, and accessibility. Cavities located upon the morsal, lingual, or labial surfaces of the tooth crown are easily accessible, but those upon the approximal surfaces do not give ready access until after space has been gained by some of the methods of temporary separation described in the preceding chapter. Small cavities located upon any exposed surface can best be opened by the use of some form of small engine hur. The forms of burs best adapted to the opening of small accessible cavities are the pointed fissure, dentate, round, and inverted cone. Figs. 368 and Fig. 368. • Fi«sure, pointed Dentate. 369 illustrate these forms. The pointed fissure bur is by far the most service- able instrument for opening very small cavities or fissures. Its shape facili- tates its entrance into the cavity, while it also more readily follows a fissure. Spear-pointed drills are not so serviceable for this purpose, on account of the fact that they are frequently broken by being caught in the irregu- larities of the cavities or in the fissures. 16 242 OPERATIVE DENTISTRY. In the larger cavities enamel -chisels are much more useful for opening the cavity, and are less i)ainful to the patient. In using enamel-chisels Fig. 309. Round. IiiYerted cone. advantage is taken of the natural lines of cleavage of the enamel, as shown in Fig. 370, a, h. The overhanging edges of the enamel are thus rapidly Fig. 370. Diagram Illustrating cleavage of the enamel and lines upon which the margin should be cut prepara- tory to filling, a, chip thrown off by the chisel ; h, position of the chisel in splitting off overhanging margins ; c, c, correct lines upon which to cut the margins preparatory to filling ; d, d, incorrect lines for the preparation of the margins for filling ; /, cavity in the dentin. (After Black.) and effectually cut away. The selection of the form and size of the chisel should depend upon the size, location, and the accessibility of the cavity. Fig. 371. A set of three-edged chisels recently invented by E. Parmley Brown (Fig. 371) are most admirable for opening cavities, enlarging fissures, cut- PEEPARATION OF CAVITIES. 243 ting away overhanging edges of enamel, and trimming the cervical margins of cavities. Other forms of chisels are shown in Fig. 372. Fig. 372. Chisels may be nsed either with hand-pressure or by the driving force of the mallet. The sharp, quick stroke of the mallet is the most effectual force to use in cleaving the unsupported edges of the enamel, while there is much less danger of the instrument slipping and injuring the soft tissues of the mouth or the pulp than when hand-pressure is used. The chisel should be held between the thumb and first two fingers of the right hand, as a pen is held, while the ring and fourth fingers rest upon an adjacent tooth or some convenient part of the face or chin, to guard against slipping. This position of the hand in holding the chisel applies equally to the engine hand-piece, excavators, mallet pluggers, and other small-handled instruments. In opening cavities upon the approximal surfaces which have been brought to view by separating the teeth, and which are sui^erficial and of limited extent, small round or inverted cone-shaped burs will be found most useful ; while in cavities of larger size one of the smaller sizes of the Parmley Brown chisels, which cut upon the sides as well as the point, will be found advantageous in cleaving the thin edges of the enamel. They are also especially useful in preparing approximal cavities in the incisors and cuspids, and for trimming enamel margins. Time will be saved in the affcer-procedure of removing the decay if in 244 • OPERATIVE DENTISTRY. the operation of opening the cavity the overhanging enamel has been at once cut away until sound dentin has been reached. The unnecessary sacrifice of enamel-tissue is, however, to be avoided, but nothing is gained by temporizing. In the heroic use of the enamel-chisel in the first step in the operation of cavity preparation lies the secret of rapid excavation, while much pain and fatigue will be saved to the patient and better results will follow than by timid, half-hearted measures. Removing the Decay. — In removing the softened decalcified dentin from a carious cavity care should be exercised to inflict as little pain as possible. Its thorough removal, however, is absolutely necessary to the success of the after-treatment. The method of operation to be adopted in removing the carious dentin will depend upon the character and con- sistency of the disorganized material to be excavated. These characteris- tics of the decalcified dentin may be divided into three varieties : one is white and of chalky consistency, another is light brown, semi- elastic, or leathery, and the last dark brown or black and quite hard. In the Jirst variety, which is characteristic of the most rapid form of caries, the dentin is often exquisitely sensitive, Spoon-bladed or round-bladed excavators will be found most useful in removing the decalcified tissue, and the risk of exposing the pulp will be much less than if engine-burs are used, from the fact that the decalcifica- tion of the tissue has many times progressed almost to the pulp before the cavity has been discovered. In the second variety, having a semi-elastic, leathery consistency, exca- vators having round or spoon blades (Fig 373) will also be found most serviceable in removing the carious dentin. This character of decay is most often seen in the teeth of young people, and is not infrequently very sensitive. In all operations for removing carious dentin, the fact should be kept constantly in mind that the most sensitive portion of a tooth is at the periphery of the dentin, immediately beneath the enamel, and that the dentinal fibrillse, in advancing from the pulp to the i)eriphery of the dentin, have a direction which is perpendicu- lar to the surface of the tooth. Much pain may, therefore, be saved the patient if at the outset of the operation a few bold sweeps of the excavator are made around the circumference of the cavity immediately beneath the enamel, and that all subsequent cuts of the excavator, so far as possible, follow a line from the centre of the tooth to the periphery, rather than from the periphery to the centre. In the leathery form of carious dentin, many operators advise removing the dentin layer by layer, beginning at the periphery of the cavity and gradually lifting them out until all of the material of this character has been removed. The excavator should be kept sharp, and each cut of the instrument should be decided. Scraping of the sensitive dentin is much more painful than a firm, decided cut that accomplishes something. The greatest kind- ness that can be shown a patient under these circumstances is to be thorough, but at the same time rapid ; and these conditions are not inconsistent to the mind of the bold but conscientious operator. PREPARATION OF CAVITIES. 245 ThoroTigli excavation of a cavity comprehends the removal of all dis- organized and infected dentin. This may not always be done with safety Fig. 373. ni fi 1? M 1 1 M f s ff n Excavators. to the pulp, but, as a general rule, this procedure should be carried out. There is only one way to determine when all infected tissue has been re- moved, and that is by the density of the tissue. All soft, leathery dentin is 246 OPERATIVE DENTISTRY. infected, but Miller has proved that all partially decalcified dentin is not infected, as the process of decalcification is always in advance of the presence of the micro-organisms in the tubuli. The meaning of the term thorough excavation would necessarily, then, depend somewhat upon the judgment and experience of the operator as to whether all infected tissue had or had not been removed. The only safe method, except in the case of nearly exposed pulps, is to excavate until sound, hard dentin has been reached. Partially decalcified dentin may be allowed to remain in the bottom of the cavity, as recalcification will usually take place in this tissue, and also for the reason that it will protect the pulp from thermal shock. Thorough disinfection should, however, precede the introduction of the filling. For this purpose mercuric bichloride 1 to 500, carbolic acid ninety-five per cent., oil of cloves, oil of peppermint, or listerin, etc., may be used. In the operation of removing the decayed dentin the surfaces of the cavity should be left as smooth as possible. Undercuts, grooves, or gen- eral unevenness of the walls of the cavity should be avoided, except those which are made for the definite purpose of retention, as the filling- material is more readily adapted to smooth walls. In the tliirdj or dai% hard variety^ the carious process is very slow and sometimes becomes arrested or self-limited. In arrested caries the dentin is always of a darker color than ordinary dentin, and might be mistaken for caries but for its greater hardness. It should not be removed except from the margins of the cavity, where its color would be objectionable and prevent a clear, clean appearance of the finished operation. The dentin in the dark variety of caries is not more sensitive usually than dentin in its normal state. Cavities of this character rarely penetrate to a depth involving or jeopardizing the integrity of the pulp ; conse- quently they are the most favorable cases for restoration by plugging with gold. Retentive Shaping. — After the cavity has been cleared of all disor- ganized and infected tissue, the next step in the operation of cavity prepa- ration is to give it such shape that the filling, after it has been inserted, cannot be mechanically dislodged ; while at the same time the retentive shaping must not be carried so far as to weaken the walls or to endanger the pulp. These points cannot be too strongly emphasized, for upon their proper appreciation and practical application will largely depend the future success or failure of the completed operation. Upon a correct application of the laws of mechanics to the art of filling teeth will de- pend the retention of the filling after it has been inserted. The shape of the cavity must therefore be such that the completed filling cannot be dis- lodged by mechanical force without fracturing the walls of the cavity or cutting the filling into jDieces. It is obvious, however, that a single method of securing retention will not suf&ce for all cavities. Various methods must therefore be employed, and their individual or combined application must depend upon the general form and character of the cavity to be filled ; but, as a general PREPARATION OF CAVITIES. 247 rule, it may be stated that the cavity should be slightly larger at the bottom than at the orifice. In small cavities, however, in which the depth is equal to or greater than the diameter, the walls may be left parallel to each other, as the lateral walls will contain a sufficient number of uneven points to secure retention of the filling. In shai^ing the cavity, care should be used to leave the walls as free from angles as possible, as there is greater difficulty in ada^Dting the filling to such surfaces. To this end the excavators used should be of the spoon or rounded form and the burs either round or oval. The reverse of this is true in cavities of larger size, where the diameter of the cavity is greater than its depth. Guilford formulates two rules to govern these conditions, as follows : '*!. When the depth of the cavity is greater than the diameter of the orifice jDarallel lateral walls will prove retentive. ''2. When the diameter of the orifice is greater than the dejith of the cavity the latter will have to be somewhat enlarged internally to* retain the filling." ■ ■ The first class of cavities are usually found occurring in the pits, upon the lingual surfaces of the superior incisors, the morsal surfaces of the superior and inferior bicuspids and molars, the lingual surfaces of the superior molars, and the buccal surfaces of the inferior molars. The second class of cavities are found in nearly all locations upon the various surfaces of the crowns. In some cases the cavities formed by decay will be found to possess a retentive form after the carious dentin has been removed, but, as a rule, retentive shaping will be required, making it necessary to cut away more or less sound dentin. Care should be exercised, hoivever, not to carry this part of the operation too far, as the walls of the cavity would thereby be weak- ened, or the pulp encroached upon to such an extent as to cause after- trouble. The tendency of the student and the young practitioner is to carry retentive shaping too far. Beep undercuts, grooves, or pits are not necessary to retain a filling. These means of retention are just as effective from the mechanic stand- point if they are of moderate depth as though they were much deeper, while the dangers from fractured walls or pulp irritation are greatly lessened. Approximal cavities in bicuspids and molars should be so shaped as to secure as broad and flat a foundation as possible at the cervical wall for the support of the filling. The laws of engineering require that the base or foundation of a structure shall be equal to, or greater, in surface area than the structure to be reared upon it. This applies with as much force to filling teeth as to building suspension bridges, twenty-story buildings, or Eiffel towers. The greater the load to be carried, the broader and stronger must be the foundations upon which the load is to rest. If this fact is appreciated and applied to the preparation of this class of cavities, there will be many less failures in approximal fillings in bicus- pids and molars. 248 OPERATIVE DENTISTRY. i scribed Eetentive forms may be given to cavities by making the bottom of the cavity slightly larger than the orifice ; by the formation of shallow grooves at opposite points at the base of the Fig. 374. cavity ; by pits drilled at opposite points ; or by a combination of these means of retention. In compound cavities — those involving two or more surfaces — retention is often strengthened by giving a dove-tail form to one portion of the cavity. Occasionally, on account of the loss of tissue, retention cannot be ob- tained by any of the means just de- it then becomes necessary to secure the filling by setting one or more screw-posts. These posts may be set upon opposite sides of the cavity, with an inclination towards each other, or a single post may conserve the purpose of retention. Fig. 374 shows a set of instruments for this purpose. In setting these posts, a spear- pointed drill is used to make the hole which is to receive the post ; this is followed by a tap, cut with the same thread as that upon the gold wire used for the post, and of the same size. A post of suitable length is then cut from the wire and set in the hole prepared for it. It is never wise to set a post or make a groove or pit in the incisal or morsal surfaces of the tooth or very near the enamel, as their presence tends to weaken this part of the tooth and makes fracture of the walls very liable to occur under the stress of mastication. Forming Cavity Margins. — This part of the ojieration is also an ex- ceedingly imx^ortant one, from the fact that without a proper forming of the cavity margins perfect adaptation of the filling-material to the enamel borders is an impossibility, and consequently leakage soon takes place at these defective points and the operation becomes a failure. Another im- portant point in the process of shaping the margins of the cavity is to cut away all thin and weakened enamel, for if it is allowed to remain fracture is liable to occur either in adapting the filling-material to it or in the stress incident to mastication. In the final preparation of cavity margins, the best results will be obtained by slightly bevelling these borders by cutting the enamel-rods in an oblique direction, as shown in Pig. 375, c, c. If the walls are cut per- pendicular with the wall of the cavity, as in d, d, certain of the enamel- rods would have no support of dentin, and consequently they would be more liable to fracture from cleavage than if cut away as shown in c, c. In cavities occurring upon concave surfaces, as, for instance, in the fissures upon the morsal surfaces of bicuspids and molars, the lines of enamel cleavage would have an inward direction, the reverse of that shown at d. The bevel, therefore, given to the enamel margins in this class of PEEPARATION OF CAVITIES. 249 cavities should — in order that no enamel-rods be left without proper sup- port of the dentin — be a little greater than that given to the margins of cavities occurring upon convex surfaces. Fig. 375. The instruments which are best suited to the purpose of preparing the enamel margins are chisels, broad- face hoe excavators, barrel- shaped file- cut burs, and Arkansas stones. The margins should be left as smooth as possible, but in the use of the burs and stones care must be exercised not to round the edges of the margins, as this would leave a feather-edge to the filling after it was finished, and would be liable to peel up or become rough, thus spoiling the appearan(;e of the marginal contact and opening the way for the establishment of secondary caries. CHAPTER XVII. TREATMENT OF CAEIES BY OBTUEATIONj OR FILLING. Definition. — Obturation (from the Latin obturare, to stop up), the act of stopping a hole or covering an opening. " Obturation of the Teeth. — The filling of cavities in the teeth pro- duced by caries with a substance capable of resisting the destructive action of fluids or the force of mastication." The operation of removing disorganized substances from a carious tooth and mechanically filling, stopping, or plugging the cavity should, strictly speaking, be termed an obturation, and the inserted filling an obturator. Custom, however, sanctions the use of the term filling, etc., as applied to the closing of a cavity in a tooth, and generally restricts the use of the term obturation to the mechanical procedure of stopping or covering an opening in other tissues caused by developmental defects, disease, acci- dent, or surgical operation, and of obturator to the instrument or appli- ance which closes or stops the opening. The introduction of a filling-material into a prepared cavity in a tooth is a purely mechanical procedure, but one which, nevertheless, with certain materials, like gold-foil, calls for a high degree of mechanical ability and manipulative skill. Upon the possession of these qualifications will de- pend, in no small degree, the success or failure in saving the teeth by the operation of filling. It matters not how perfectly the cavity may have been prepared, if the completed filling is faulty in its adaptation to the walls of the cavity and the enamel margins, — in other words, does not hermetically seal the cavity, — or the margins are not perfectly finished, or the surface is rough or not properly contoured, the final result will be failure. The main objects in introducing a filling into a prepared cavity are to arrest the further progress of the carious process and to restore the tooth to its original form and usefulness. The consideration of the ways and means by which these results may be obtained must comprehend, — (a) The age of the individual ; the character of the teeth ; the condi- tion of the health, and the local environment ; also, (b) The nature and physical characteristics of the substances used as filling-materials. (c) Their capabilities of perfect adaptation to the walls of the cavity and the restoration of contour. (d ) Their conductivity and therapeutic action upon tooth-structure. (e) Their resistance to chemical action and mechanical abrasions ; and, (/) Their harmony of color with tooth-tissue. In the selection of the material with which to successfully fill a tooth an experienced judgment is required. This judgment in any given case must be based upon a full knowledge and appreciation of all the condi- tions presented by the individual to be operated upon, as well as the 250 TREATMENT OP CARIES BY OBTURATION, OR FILLING. 251 nature, physical characteristics, and adaptability of each of the various materials that are generally used for this purpose. In a wise selection of the material to be used in each individual case lies one of the most im- portant elements in the conservation of decayed teeth. The dentist who fails to appreciate this fact will fall far short of render- ing the best possible service to his patients. FILLING- MATERIALS AND THEIR INTRODUCTION. The materials which are used for filling teeth are divided into two general classes, — viz., non-plastics and plastics. The non-ploMics include all of the various forms of gold-foils, sponge or crystal gold, platinum gold-foil, and tin-foil. The plastics are amalgams, gutta-percha, and the various basic oxide cements. The ideal filling-material, like the "fountain of life," still lies within the realm of the undiscovered. No substance or combination of substances yet discovered possesses all of the features and characteristics necessary to fulfil the requirements of the ideal material for filling teeth. Such a filling must be indestructible in the fluids of the mouth, and not suscep- tible to chemical change in the presence of substances which enter the mouth as aliment or as medicinal remedies ; it must be easy of adaptation and capable of making a moisture-tight plug ; it must be so dense in structure as to retain its form and resist the abrasion of mastication ; capa- ble of being colored to match any shade of the natural teeth, and polished or glazed to imitate the enamel ; it must be a non-irritant and a non-con- ductor of thermal changes ; incapable of shrinkage or of staining the tooth-structure, and possessed of such adhesive and cohesive qualities as will retain it in any imaginable location and permit of the most elaborate contouring ; and, finally, it should possess such therapeutic properties as to make it preservative of tooth-structure. NON-PLASTIC MATERIALS. Gold. — Of all the materials that have thus far been used for filling carious cavities in the human teeth none possess in so high a degree so many of the desiderata of a perfect filling-material as gold, and yet this material falls far short of the ideal. Gold, nevertheless, by reason of its peculiar physical properties, occu- pies the first place among the materials which are used for this purpose, and experience teaches that after all the constitutional and local conditions and environment are considered, gold in the majority of instances is the most reliable material with which to preserve the teeth and restore portions lost by disease or accident that the dentist at the present time has at his command. PHYSICAL CHARACTERISTICS OF GOLD. Until the publication of the experiments of Dr. Black with regard to the "Physical Characteristics of Filling-Materials," very little was known of the behavior of gold and gold fillings under stress, such as would be exerted in the mastication of foods. In order to obtain data that would be reliable this investigator began 252 OPEEATIVE DENTISTRY. his experiments with cast, hammered, and annealed gold of the same purity as that used by the dentist in filling teeth. The object of this was, first, to determine the amount of their strength and flow under stress of a given number of pounds, and then to compare these results with the strength of fillings made from the various preparations of gold-foil, etc., by the differ- ent methods of manipulation. Strength of Gold. — Blocks were prepared from bars of cast and ham- mered gold by turning in a lathe to an even size of one-hundred-and-forty- thousandths (fourteen one-hundredths) of an inch, and cutting pieces from the bar of the lengths which appear in the accompanying table, the ends being accurately squared. The specific gravity varied from 19.1 to 19.3. These were then subjected to compression in a dynamometer with a micrometer attachment. The pieces were placed with their squared ends between two parallel planes of steel, and the shortening of the blocks un- der a stress of two hundred pounds and three hundred pounds noted. The same sections of hammered gold were afterwards annealed and again subjected to the same stress, with the result of finding them much softer and much more yielding to the same pressure or stress. This is also shown in the table. Exhibit of the Strength of Cast, Hammered, and Annealed Gold under Compression. All results reduced to the basis of one-teu'th 0) a c '53 Per cent, of shortening under a stress of 200 lbs. 300 lbs. 350 lbs. Case 1. Cast gold, chemically pure. Specific gravity, 19.2 ; diameter, 140. 1 2 3 4 108.5 107.5 107.25 106.0 486.9 481.9 479.8 477.8 4.24 4.27 3.91 5.07 9.22 12.16 11.76 11.70 4.37 11.21 Case 2. Cast gold, chemically pure. Specific gravity, 19.25 ; diameter, 120. 1 2 3 4 86.0 101.0 98.0 83.0 284.2 339.7 316.4 274.5 1.79 4.08 2.62 L85 8.39 8.66 9.36 9.30 13.18 17.34 14.19 13.03 2.58 8.92 14.43 Case 3. Hammered gold, pure. Specific gravity, 19.3 ; diameter, 140. 1 2 113.0 121.0 490.6 534.3 0.33 0.63 1.35 2.53 2.72 5.07 0.48 1.98 3.89 The same pieces annealed. 1 2 6.34 6.01 12.70 12.71 16.23 16.71 6.17 12.70 16.47 Case 4. Hammered gold. Specific gravity, 19.35; diameter of pieces, 115. 1 2 3 4 170.0 121.0 122.0 109.0 492.0 372.4 380.0 323.5 0.88 0.40 0.40 0.53 2.94 1.64 1.64 2.24 10.00 6.14 3.68 7.13 0.55 2.08 6.73 The same blocks after annealing. 1 2 3 4 3.14 6.75 6.63 5.06 12.93 14 41 14.16 13.76 18.18 19.36 19.02 19.22 5.39 13.38 18.94 TREATMENT OF CARIES BY OBTURATION, OR FILLING. 253 Flow of Gold. — Dr. Black says, "As stress upon gold is increased to a point at whicli it begins to show signs of failure or yielding, it begins to flow or spread laterally. At first this flow is very slow, but as the stress is increased the flow occurs at a constantly increasing ratio." He found, however, that gold possessed the peculiarity of irregularity in its flow under pressure, the movement being rapid for a little time, then stop- ping, and again flowing. This was observed to invariably occur no matter how steadily the pressure was increased. It is generally recognized that gold is made stronger and denser by hammering and rolling. For the purpose of comparison with cohesive gold fillings, bars of gold were hammered as thoroughly as their size would permit. Hammered blocks of gold gave no evidence of flow at a stress of one hundred and fifty pounds. The average shortening under two hundred pounds' stress was 0.48 per cent.; at three hundi^ed pounds', 1.98 per cent.; at three hundred and fifty pounds', 3.89 per cent. To test the strength and flow of gold fillings under stress, he caused to be made forty-eight fillings of the different preparations of cohesive and non-cohesive gold. Dr. Black made ten of these himself; the other thirty- eight being made by twelve different operators. These fillings were made in square and round cavities in a steel apparatus especially constructed for the purpose. The greater number were made in the square cavities, which measured one-third of an inch ; others in round cavities giving the same area in cross-section, but a considerable -number were made in larger cavities. The only fillings that showed a specific gravity greater than that of hammered gold (19.3 or 19.4) were those made by Dr. Black. The first two were made with the intention of obtaining the highest specific gravity possible. In one a heavy mallet was used, and in the other a hammer, the force used being much greater than would be employed in filling a tooth. The specific gravity of the first was 19.38 ; of the second, 19.42. The third filling was malleted as would be usual in making a filling that would be exposed to unusual stress. The specific gravity of this filling was 19.18. The specific gravity of the other fillings ranged from 18.61 to 10.7. The highest specific gravity of a cohesive gold filling was 18.61, and the lowest, 10.7. The highest specific gravity of a non-cohesive gold filling was 18.2 ; the lowest, 16.9. Dr. Black found in making test fillings of purely non-cohesive gold, by the old method of wedging and hand-pressure, that a sj)ecific gravity of 16. was about the best that could be done with a force that was admissible in filling teeth. These fillings went to pieces under very slight stress. This of course was hardly a fair test of the strength of non-cohesive fillings. Such fillings should be tested under conditions similar to those obtaining when they are sai)ported by the walls of a tooth cavity. There is no doubt, however, that the strength of these fillings under stress is much below that of cohesive gold. Dr. Black recognizes this fact when he says, "Of course it must be understood that fillings made of purely non-cohesive gold depend upon 254 OPERATIVE DENTISTRY. the support of the walls of the cavity for their strength, and tests of naked fillings are of little value, but the facts developed in this way may be in- structive to many in the placing of non-cohesive gold in the beginning of fillings in proximate cavities. It shows that it must be used in moderate amount, and so placed that it will be properly supported, or the strength of the filling will be notably impaired." Gold fillings are often required to carry a stress of from one hun- dred to one hundred and fifty pounds, and even more in persons with strong masticatory apparatus. Gold fillings, in order to successfully carry a stress of one hundred pounds upon an area one-tenth of an inch square. Dr. Black thinks, must have a density or specific gravity ''of about 17.0, and be pretty well hardened by malleting." A filling one-tenth of an inch square, carrying a stress of one hundred pounds, should have a base equal to its size to rest upon. Dr. Black says, " If we obtain a flat gingival wall in a proximate cavity in a bicuspid tooth of only five-hundredths of an inch in breadth (one-twentieth of an inch) it will have to be full two-tenths of an inch long for the gold placed upon it to support one hundred pounds' stress, and to make it support one hundred and fifty pounds is out of the question." In approximal cavities in bicuspids and molars it has been a quite common practice to groove or undercut the buccal and lingual walls as a means of retention or anchorage. This method of preparing the cavity does not place these walls in a position to assist in carrying the load, but rather weakens them ; and if "the seat of the filling is disturbed ever so slightly under stress, these walls are liable to be fractured, or the filling is drawn away from them, thus destroying the object for which it was inserted, by permitting the entrance of the agencies of decay and the ultimate de- struction of the filling. A better method is to prepare the cervical wall or base of the cavity as flat as possible, and the buccal and lingual wall without grooves or undercuts, and depend for support of a large part of the stress by cutting an additional seat in the morsal surface of the crown, and so shape this seat by dovetailing or other form as to give it good retentive powers. Platinum-gold fillings showed a slight advantage in strength over those made of pure gold at the same time and under the same circumstances, but the difference was not so marked as was anticipated. The difference found in the specific gravity of the fillings made for these experiments is explained by the difference in the consolidation of the gold, or, to state it in another way, was due to the difference in the number of air-spaces which the fillings contained. The flow of gold fillings, with a specific gravity of 17.0 and above, under the ordinary stress of mastication is so small as to be a matter of little consequence. Under a stress of one hundred and fifty pounds api^lied to hammered gold no evidence of flow was observed, while at two hundred pounds, a stress entirely out of the ordinary during mastication, it was only 0.48 per cent. The surprise, however, lies in the fact that fifty per cent, of the test TREATMENT OF CARIES BY OBTURATION, OR FILLING. 255 fillings, as shown by the exhibit, fell below the indicated specific gravity of 17.0, a density necessary to carry a stress of one hundred pounds upon a one-tenth-inch area, and could not, therefore, be expected to carry the required stress, while twenty-nine per cent, were below 15.0 in specific gravity, and readily gave way under a stress of one hundred and fifty pounds. THE PROPERTIES OF GOLD-FOIL. The properties of gold-foil which give it its great value as a filling-mate- rial are its toughness, softness, and pliability, which permit it to be readily adapted to the walls of the cavity ; its tenacity, which facilitates its intro- duction and consolidation ; and its resistance to mechanical abrasion. It, however, possesses an objectionable color, and yet it is the least objection- able in this respect of all the metals that are used for. this purpose. Miller in testing for antiseptic properties in gold-foil found that un- annealed foil — Pack's pellets and Abbey's foil — retarded the growth of the mouth bacteria, while the same gold annealed had no effect. Some prepara- tions of platinum-gold and si^onge-gold acted in a similar manner. Chemically, gold is inert as a filling- material. It possesses no thera- peutic property upon tooth-structure, and it is not acted upon by any substances which are found within the mouth or that enter this cavity. Gold-foil as used by the dentist for filling teeth is prepared in two dis- tinct forms, which are distinguished from each other by the terms cohesive and non- cohesive. These terms are applied to designate the distinctive quality of which each is possessed. Foils are manufactured from pure metal by the processes of beating and rolling. Absolute i)urity, however, is not essential in the manufacture of foils. A small amount of alloy does not injure the working qualities in the least. All light-weight foils are made by beating, and heavy foils by rolling. The bullion is first melted and poured into ingots of suitable size ; these are then rolled into thin ribbons about one inch wide and a little thicker than ordinary note-paper, the thickness being governed by the weight of the foil to be produced ; the ribbons are then cut into inch lengths, each of which will weigh two, three, four, five, or six grains, ac- cording to the weight of the foil it is desired to make. These squares are then laid between sheets of goldbeater' s-skins made from the intestines of bullocks ; vellum paper made to imitate the skins is now extensively used because of its cheapness. These skins are cut into five-inch squares, and from one hundred and sixty to one hundred and seventy of them piled one u^Don the other, with a square of rolled gold between each, and the pile wrai^ped in heavy parchment, being bound both ways, so that all of the edges are protected. This package is then placed upon a heavy stone block or pillar, three feet high by fourteen to fifteen inches square, and resting upon a large wooden block, which is set in the ground from three to four feet to give it solidity, the upper end or face of the stone pillar being smooth and polished. Then with a heavy, round-faced steel mallet the package is beaten with heavy blows, and after each stroke of the mallet it is turned 256 OPERATIVE DENTISTRY. one-quarter around. The time consumed in beating out sucli a package of gold is usually from two to three hours. After the foil has been beaten to the desired thinness, the leaves are separated, trimmed, and placed in paper books ready for use. Eolled gold is made by passing it through specially prepared mills until the desired thinness is obtained. All foils as they come from the beater's- skins or from the rollers are non-cohesive. The cohesive quality is developed by a process of slow heating or annealing. The light-weight foils in both the cohesive and non-cohesive forms are those most commonly used, Nos. 3 to 6, and of these, ISTo. 4 is generally preferred. These numbers indicate the weight of each sheet in grains. Eolled foil varies in weight from twenty to two hundred and forty grains to the sheet, and is always prepared in the cohesive form. ISTos. 20 and 30 are the most popular at the present time, although a few years ago the heavier foils were in great demand. Cohesive gold possesses in a high degree the quality of cohesiveness, which causes the surfaces when brought in contact under pressui-e to cohere or weld. A filling made with this gold forms a solid mass, and may be afterwards hammered or rolled into plate. This quality gives great value to this form of gold as a material for restoring the contour of the teeth, but ren- ders its adaptation to the cavity walls more difficult, as the cohesive quality makes it work stiff and hard under the plugger. Non-cohesive gold is devoid of the cohesive quality and will not cohere or weld under pressure. This quality of non-cohesiveness makes it soft and pliable, and permits the surfaces of the gold to slip or slide upon each other when under pressure. This form of gold is valuable for the filling of all simple cavities, by reason of the fact that it is easy of adaptation to the walls of the cavity and can be very rapidly introduced. The difference between these two forms of gold does not appear to de- pend upon their degree of purity, but rather to some trifling change in the physical condition, the nature of which is not definitely understood. If non-cohesive gold is thoroughly annealed it becomes cohesive, while if cohesive gold is exposed for a time to the atmosphere it becomes non- cohesive. A few drops of aqua ammonia placed upon a pledget of cotton and left overnight in a box containing cohesive gold will render it non-cohesive, while the cohesive quality may again be restored by annealing. The non- cohesive quality would therefore seem to be due to some accu- mulation or deposit formed upon the surface of the foil. The process of annealing appears to drive this off, leaving the surfaces absolutely clean and thus rendering the foil cohesive. Black, in experimenting to ascertain the causes of this peculiarity, de- monstrated the fact that if gold foil is subjected to the fumes of ammonia, hydrogen, hydrogen carbide, hydrogen phosphide, sulphur, phosphorus, or sulphurous acid gas, its cohesive quality is quickly destroyed. Annealing restored this quality except in those samples which had been exposed to TREATMENT OF CARIES BY OBTURATION, OR FILLING. 257 the fumes of sulphur and phosphorus. In these the cohesive properties of the foil were permanently destroyed. It is therefore important, especially during the winter months, that cohesive foil be excluded as much as possible from the atmosphere, which is then more or less impregnated with the gases arising from the combus- tion of coal. He further demonstrated that the fumes of ammonia have the power of preventing the deleterious effects of other gases upon the foil, and recommended that the foil be subjected to this gas by keeping with it in the drawer a vial of ammonium carbonate. I^on-cohesive foil was the only preparation of gold used by the earlier operators in filling teeth. Fifty years ago the cohesive property of gold- foil had not been discovered, and yet what marvellous operations such men as Westcott, Dwindle, Maynard, Clark, and others were able to make with non-cohesive foil. Their skill in the use of this material was really won- derful, for many of them succeeded in making most beautiful contour operations in approximal cavities of bicuspids and molars, many of which have resisted decay and withstood the wear and tear of mastication for several decades without losing their beauty of form and finish. These same men, upon the discovery of the cohesive quality of gold~ foil, saw the great advantages to be derived from the discovery, and adapted it at once, to the salvation of broken-down teeth that were ^^^' ^^^■ bej'ond successful filling with " non- cohesive foil, and which otherwise would have been condemned to the forceps. So enthusiastic did some of them become that they were not content with restoring the contour of one-half of a tooth, but even restored the whole crown. Restorations of this character with cohesive gold were later carried to a very high degree of perfection by Dr. Marshall Webb. The ac- companying illustration. Fig. 376, shows the extent to which he carried such restorations, are restorations of from two-thirds to three-fourths of the crown, while c, g, and h show restorations of the entire crown. The differences in the working qualities of cohesive and non-cohesive gold-foil make it necessary to use two distinct methods of operating. a, b, d, e, f, NON-COHESIVE FOIL. Non-cohesive foil is best adapted to cavities which have/oztr walls, such as are found upon any of the free surfaces of the crown. Successful operations can also be made with it in cavities having three 17 258 OPERATIVE DENTISTRY good walls, as, for instance, in compound approximal cavities in the bi- cuspids and molars. Non- cohesive, wiannealed, or soft foil is tlie most ductile of all the forms of gold used by the dentist, and for this reason it does not "ball" under the instrument, is very readily adapted to the walls of the cavity, and insures a moisture-tight plug. The method of introducing it into a prepared cavity is to first prepare the gold in the form of cylinders, ropes, ribbons, or pellets of various sizes and density, the cylinders and pellets a little longer than the depth of the cavity to be filled. The cylinders are prepared by winding a ribbon of foil around a small Swiss broach, the ropes by rolling a strip of foil in a napkin, and the pellets are made by tearing the foil into small fragments and rolling them between the thumb and index-finger. Cylinders, however, are to be pre- ferred to pellets, from the fact that they can be prepared with more uni- formity in size and length than is possible in making pellets. The cylin- ders should be made of such size and density that several will be required Fig. 377. to fill the cavity, and of such length that when jjlaced upon their ends in the bottom of the cavity they will project slightly from the orifice. These may be obtained from the manufacturer already prepared, as shown in Fig. 377, but the writer always prefers to prepare the gold for each in- FiG. 379. Fig. 378. Foil-carriers (reduced). Cylinders and mats in the act of being intro- duced into a crown cavity. dividual case as it is presented rather than to depend upon material prepared in advance, as this is very rarely just what is required. TREATMENT OF CARIES BY OBTURATION, OR FILLING. 259 The cylinders or pellets are then placed in the cavity with foil-carriers (see Fig. 378), being arranged side by side around the circumference of the cavity and condensed against its walls with suitable pluggers. Other cylinders or pellets are placed in like manner, and these are condensed towards its walls by the use of the wedging process, and this method con- tinued until the filling is finally finished by a single hard- rolled pellet forced into the centre. No instruments are better adapted for this purpose than those shown in Fig. 380, made from patterns furnished by Dr. Bing. Fig. 380. Bing pluggers. The cylinders, if the filling has been properly introduced, should pro- ject a little above the surrounding tooth surface. These should now be thoroughly condensed by hand-i^ressure or the mallet. Large serrated, round-faced foot-pluggers, as shown in Fig. 381, are the best for this pur- pose, as pluggers with sharp angles are liable to pulverize the enamel margins, if by chance they should come in contact with them. Thorough condensation, directed always towards the cavity walls, is of the utmost importance in finishing the fillings. The surface should next be bur- nished, also towards the enamel margins, and the surplus gold cut away with finishing burs, stones, or the file, as the location of the filling may make most convenient, and the surface polished with sand- paper disks, emery strips, and pulverized j)uniice-stone or rouge, or burnished. 260 OPERATIVE PENTISTRY, Many operators who use non-coliesive foil employ tlie hand mallet all through the operation in i3reference to the exclusive use of hand-pressure. The stroke of the mallet is entirely different from the tapping stroke used in welding cohesive foil. The object in malleting non-cohesive foil is to utilize to its fullest extent the sx)reading quality or flow of this Fkj, 381. form of gold, and this can only be accomplished by a firm f^ driving blow, such as would be used in driving a nail of the same size as the plugger-point with which the gold is being packed, or it may be expressed as a lingering stroke that follows the plugger and remains upon it until the force of the impact has been exerted to its fullest extent upon the gold immediately beneath the plugger. The stroke, however, must be graduated to the size of the plugger and the strength of the walls of the cavity, otherwise damage might be done by driving the point of the plugger against the margins of the cavity or fracturing its walls. In compound approximal cavities (mesio-morsal or disto-mor- sal) in the bicuspids and molars the filling is commenced at the plugger? cervical wall by placing two or three cylinders side by side, with the ends projecting beyond the cavity, and condensing them against the cervical margin with broad-faced pluggers. This process is to be repeated until the morsal surface is nearly reached, when the cylinders should be condensed against the morsal margins with foot-shaped pluggers, and the filling finally finished in the centre with a rope or a single hard- rolled pellet. Final condensation should begin at the morsal surface and be gradually carried over to the approximal, using the round-faced foot-pluggers for this purpose. The amount of contour obtained by this method will de- pend upon the distance that the cylinders projected beyond the walls of the cavity at the approximal surface and the thoroughness with which they were condensed in building the filling. Many oi3erators prefer to use non-cohesive foil for the base of the cavity and cohesive foil for the remainder. If this method be pursued it will be necessary to partially anneal the pellets which are to form the last layer of non-cohesive foil, as by this means the cohesive foil can be welded to it. Or the cohesive foil may be driven into the surface of the non-cohesive foil by small wedge-shaped pluggers. Another method is to pack non-cohesive foil against the walls of the cavity and over the margins, and finish the filling in the centre with cohe- sive foil. This was a favorite method with the late Dr. Allport, and one which he practised for many years. In approximal cavities in bicuspids and molars he always used non- cohesive foil at the cervical margin, claiming that he secured a better adaptation of the gold to the cervical wall than was possible with cohe- sive foil, and that from the fact that large cylinders or pellets were used for this purpose, and thoroughly condensed with a broad-faced foot-shaped plugger, there was less danger of injuring the cervical margin than when TREATMENT OF CARIES BY OBTURATION, OR FILLING. 261 coliesive foil was used, as with tlie latter it was absolutely necessary to use small pieces of foil and condense them with small pointed pluggers to secure perfect adaptation, while the danger of bruising the cervical margin was greatly increased by the liability of the plugger to being driven through the gold. Hopes and ribbons are used by some operators in preference to cylinders and pellets. These are made from one to two inches in length, a sheet of foil being cut into two to four equal strips and rolled in a napkin to form ropes, or folded with a spatula to form ribbons. The method of introducing the rope and the ribbon is to grasp one end of it with the foil tweezers and carry it to the bottom of the cavity, and lightly pack it against the W2,\\ farthest from the operator, then fold it over and carry it again to the bottom of the cavity, condensing it against the fold first inserted, but allowing the upper end to project slightly above the margin of the cavity. After the cavity has been about half filled in this way, another rope or ribbon may be introduced in like manner and packed against the wall of the cavity nearest to the operator, then against the lat- eral walls, and the filling finally completed by packing and wedging an- other rope or ribbon into the ojjen space left in the centre. The surface is then thoroughly condensed and finished in the manner described with the use of cylinders and pellets. This method is thought by some opera- tors to be superior to the use of cylinders, for the reason that the gold is more easily introduced and that it makes a more compact filling. This statement, however, is open to question in both of its features. Herbst Method. — Another method of packing non-cohesive gold is that introduced by Dr. Herbst, of Germany, which consists of adapting or modelling the gold to the walls of the cavity by means of burnishers rapidly rotated by the dental engine. The gold used for this purpose was a very soft form of cylinders especially prepared by Wolrab, of Bremen. Fillings introduced by this method show a most perfect adaptation of the gold to the walls of the cavity, are moisture-tight, as proved by their successful resistance of the carmine test. The surface of the filling pre- sents a burnished appearance, which is rendered very cohesive by the fric- tion and heat produced by the process of burnishing, so that each piece of gold as it is introduced adheres to the previous one which has been bur- nished into its position. The filling may be finished throughout by the same process, but better results are obtained by finishing with cohesive gold condensed by the mallet. The instruments recommended by Dr. Herbst for the introduction of the filling are shown in Fig. 382, and consist of eighteen burnishers, some of steel and others with blood-stone points of various form and size. It will be readily understood, however, that only the most accessible cavities can be successfully filled by this method ; those, for instance, pos- sessing four good walls, like the morsal cavities of the molars and bicuspids, being the most favorably located for this system. For anchoring the filling, no especial preparation of the cavity is re- quired other than that given to cavities which are to be filled with non- cohesive foil by the other method. 262 OPERATIVE DENTISTRY In starting the filling, the first cylinder introduced into tlie cavity should be large enough to cover the bottom, and it should be carried into position with a round hand-burnisher, and then followed with the engine-burnisher of the same size and form, and thoroughly adapted Fig. 382. Herbst burnishers to the floor of the cavity. Successive cylinders are then introduced and burnished against the walls of the cavity, keei)ing the edges next to the walls higher than the centre of the filling. As the filling nears completion, the cylinders should be so placed that they can be burnished against^ and over, the enamel margins. The centre of the filling can then be finished by adding other cylinders by the same method, or with cohesive gold, condensed with foot-pluggers and the mallet. Fillings made by the Herbst method are not so dense as those made with the mallet, and the surface does not wear so well, as it shows a tendency to flake and bruise under stress of mastication. Contour fillings cannot be as successfully made by this process as with cohesive' gold, and yet, by the use of the matrix, thoroughly good approximal fillings have been introduced in the bicuspids and molars. COHESIVE FOIL. Cohesive or annealed foil is stiff and harsh as compared with the ^ Velvety" softness of non-cohesive foil. It does not work so easily as the latter, and requires an entirely different method of manipulation for its introduction. In the manipulation of cohesive foil the student must keep in mind two rules if he would be successful in its use : first, always to use small pieces of gold ; and second, to condense them with small plugger-points. Many faulty fillings have been made with cohesive gold by not ob- serving these two important rules. On account of the cohesive quality of this form of foil it has a tendency to "ball" under the plugger and draw away from the walls of the cavity ; while if used in large pieces there is constant danger of the mass clogging and bridging in the cavity, and thus making a porous and leaking filling. Cohesive foil is prepared for introduction into the prepared cavity in the form of loosely rolled ropes, ribbons, pellets, and mats. The loosely rolled ropes are made by dividing a sheet of No. 3 or No. 4 foil into strips and rolling them in a napkin. Cohesive foil should never be handled with the unprotected fingers, as the moisture or other impurities upon the skin would destroy its welding properties. Pellets may be made by cutting the ropes into lengths varying from one- eighth to one- fourth of an inch. TREATMENT OF CARIES BY OBTURATION, OR FILLING. 263 Eibboiis are made by folding a slieet of the same foil witli a spatula to any desired width. Twice folding reduces the slieet to one-fourth its original width ; this may be cut lengthwise in strips or ribbons from one- sixteenth to one-eighth of an inch in width. These ribbons are composed of four thicknesses of foil, and in this form they constitute one of the best methods of introducing cohesive foil. Mats are prepared by folding a half-sheet or a whole one into a ribbon about one-eighth of an inch wide and cutting it into suitable length for use in the case at hand. Eibbons and mats may also be made from 'No. 20 or No. 30 foil of a single thickness by cutting it in strips of suitable widths and lengths. Some operators prefer the rolled gold to the beaten when using heavy foil, as it is claimed greater softness and ductility is obtained when the foil is prepared in this way. Introduction of Cohesive Foil. — In the introduction of cohesive foil, retention grooves or pits are necessary for starting the filling. The first piece of gold iatroduced into the cavity should be firmly anchored by packing it into the retaining grooves or pits. This may be accomplished by holding the gold in position with an instrument held in the left hand, while it is packed into place with the plugger held in the right hand and the succeeding piece welded to it ; this process being repeated until the cavity is full. Care should be exercised that only a small quantity of gold shall at any time be under the plugger for condensation, and that each piece that comes in contact with a wall or margin of the cavity shall be thoroughly adapted to it without bruising the tooth-structure. The best results are only attainable by welding each lamina thoroughly to the preceding one. Hastily made fillings are usually faulty in their adaptation to the enamel margins, and sooner or later fail from leakage and recurrence of caries. Plugging Instruments. — Cohesive foil can be manipulated either by hand-pressure or mallet force. The plugger-points which are required for adapting this form of gold to the walls and margins of the cavity and for condensation are considerably smaller, and the serrations much finer than those used for non-cohesive gold. The forms which are in the most general use are the Varney, Webb, Darby-Perry, Chappell, and Eoyce, as shown in Figs. 383, 384, 386, 387, and 388. Serrated instruments are not, however, absolutely necessary for pack- ing cohesive gold ; smooth points answer equally well with rough ones. Some operators use ivory points with smooth surfaces, and hand-pressure entirely in packing cohesive gold. The ideal surface for a plugger-point for welding cohesive gold is that formed by breaking hardened steel. The nearer the serrations reproduce the roughness of this surface the nearer the plugger-point will approach the most perfect form for welding cohesive foil. Mallet force or percussion, as a means of welding cohesive gold and condensing the siirfaces of the filling, is now considered by the majority of operators as the only method by which perfect consolidation of a filling can be secured. Fillings of cohesive gold, made by hand-pressure in holes 264 OPERATIVE DENTISTEY. drilled in steel i)lates, do not weigli as mucli as those made in the same plates witli mallet forcej which jjroves conclusively that more gold can be - ESS Fig. 383. Varney pluggers. Fig. 384. 1 a ll Fig. 385. Webb pluggers. packed into a cavity, and also more perfectly consolidated, by the use of the mallet than by hand-pressure alone. The mallet was first introduced as a means of i)acking gold- foil about the year 1838, by Dr. E. Merrit, of Pittsburg, Pa., who used a hand mallet for condensing the surface of fillings which had been introduced by hand-pressure. Earlier mention was made of this instrument for consolidating gold by Koecker in his '^ Principles of Dental Sur- gery," published in 1826. Mallet force, however, was not much used until the introduction of cohesive foil. The earlier operators with this form of gold soon discovered that in order to obtain perfect union of the surfaces percussion with the mallet was superior to hand-pressure. Various forms of hand-mallets were then introduced, made of wood, ivory, and metals, weighing from one- half ounce to two ounces. The metal mallets were made of soft steel, or of lead, block-tin, and various alloys encased in metal or wood rims. The steel mallet^ Fig. 385, seems to be in the greatest favor at the present time. TREATMENT OF CARIES BY OBTURATION, OR FILLING. 265 Chappell pluggers. Fig. 388. Royce plugger-points. 266 OPERATIVE DENTISTRY. Fig. jiiiaiKii ■ WtmMM With tlie introduction of heavy gold-foils came the use of heavy mal- lets, weighing from three to four ounces or more. It was thought by those using these extremely heavy foils that heavy mallets were necessary in order to weld the surfaces of the foil. The extremes in heavy foil were soon found to be unde- sirable, except for finishing fillings, and with the decadence in the use of these foils the heavy mallet ceased to find advocates. Before the discovery that rubber sheeting or dam could be so utilized as to exclude the moisture from a cavity during the operation of filling a tooth with gold the oper- ator was obliged to employ one hand in holding the nai^kin, while the other was used to introduce the gold and consoli- date it. This made it necessary to have an assistant to do the malleting. For various reasons, however, suitable assist- ance could not always be obtained ; consequently inventive genius was called into activity, and several ingenious auto- matic mallets were devised, in which by the use of a sirring a ]3ercussioii stroke is delivered upon the plugger, similar to the stroke of the hand-mallet. The Snow & Lewis, the Foote, the Salmon, and the Abbott have found the greatest favor with the profession. Fig. 389 shows the Snow & Lewis instrument of the latest pattern. In using this instrument pressure is made upon the point of the plugger, as in packing gold by hand-pressure ; this liberates the spring, and the plunger in the upper end of the instrument is thrown forward with considerable force, the impact being expended upon the gold beneath the point of the plugger. The force of the stroke can be regulated to almost any degree to suit the desire of the operator. The Abbott instrument (Fig. 390) has a socket at each end of the handle or hand-piece, — one gives the ordinary forward stroke and the other a backward stroke. The latter was devised to carry especially formed plugger-points (Fig. 391) for condensing gold upon the distal surfaces of bicuspids and molars. The Bonwill electro-magnetic mallet (Fig. 392) is by far the most perfect mechanical mallet that has been invented for condensing cohesive gold-foil. The strokes of this mallet are delivered with great rapidity and regularity, and with such force that the gold can be most perfectly con- densed. Its essential parts are a horseshoe magnet with a hinged armature and an automatic interrupter, held in a framework or handle to support the plugger-point. The electric current may be supplied by a Bunsen or Partz battery, a storage battery, or the controlled current from a dynamo. The novice will at first find some difficulty in using this instrument with satisfaction to himself and his patient, but with a little experience he will soon learn to control it and to appreciate its merits. Snow & Lewis automatic plugger. TEEATMENT OF CAEIES BY OBTUKATION OR FILLING. Fig. 390. 267 Abbott automatic mallet (reduced). 1 n\ f^ ^^ c;^^<^=^ Plugger-points for Abbott's automatic mallet. Fig. 392. Fig. 393. Bonwill electro-magnetic mallet (reduced). Bonwill mechanical mallet. 268 OPERATIVE DENTISTRY. The Bonwill mechanical mallet (Fig. 393) was devised as an attachment to the dental engine, to be used as a substitute for the electro -magnetic mallet. Its essential parts are a small revolving wheel, having a lug upon its periphery, which strikes the plunger and delivers a blow upon the upper end of the plugging instrument. The force of the stroke is under perfect control, and the number of strokes per second may \)e increased from five to twenty, according to the speed at which the engine is run. Crystal or Sponge Gold. — This form of gold is made by two pro- cesses, one being chemical, the other electrolytic. It was first introduced to American dentists by the late Dr. Watts in 1853, under the name of sponge gold. It has been greatly modified and improved since that time, and now bears the name of crystal gold, and is one of the very best prepa- rations of cohesive gold. There are several ways of making this form of gold, but they are all embraced in three general methods, — viz., first, hy precipitation ; secondly, hy combining a certain quantity of mercm-y with the precipitate to obtain a defi- nite crystallization ; and thirdly, by electrolysis. Only pure metal can be used in the manufacture of this form of gold. In the j^rs^ method gold is added to nitro-muriatic acid until a saturated solution is obtained. It is then precipitated by the addition of sulphate of iron or oxalic acid, the precipitant being added slowly so as to obtain a crystalline or fibrous form in the deposit. The precipitate is then care- fully washed and slowly heated to nearly a cherry-red heat. After cooling it is ready for nse. The second method requires the combining of a definite quantity of pure mercury with the precipitate, and after allowing it to stand for a short time it is subjected to a mild heat, the mercury abstracted by treating the precipitate with dilute nitric acid, and washing it to remove the nitrate of mercury. It is then placed in a muffle and heated to a bright-red heat, after which it is ready for use as a filling-material. By these methods of manufacture there always remained an objection- able feature in the presence within the spongy mass of traces of nitric acid, which it was difficult or impossible to get rid of. Since the adoption of electrolysis in the place of the above methods of chemical precipitation this objectionable feature no longer exists. By this third method a certain amount of pure gold is dissolved in acids, the solution is then placed in a suitable glass vessel and plates of pure gold suspended in it. Then by means of an electric current the solution is decomposed and the gold deposited in beautiful feathery crystals. As fast as the solution loses its gold by the deposition of the crystals it is resupplied by the plates suspended in it. The deposited gold is then removed and washed to free it from any trace of the acids which held it in solution, and it is ready for use. Gold prepared by this process manifests great cohesive properties and is generally used in large contouring operations. Fillings made with this gold are as beautiful and as serviceable as any made with cohesive foil. The secret of success in the use of crystal gold is to introduce it into the cavity in small pieces, and to thoroughly condense each piece before add- TREATMENT OF CARIES BY OBTURATION, OR FILLING. 269 ing another. Failures usually result from attempts to introduce large pieces, whicli clog under the plugger, or to imperfect condensation of the gold. Gold of this variety is sold in the form of bricks containing one-eighth of an ounce each. It is prepared for the cavity either by tearing it into small irregular pieces or by cutting it into small cubes with a sharp razor. Scissors should never be used for cutting this form of gold, as it condenses the edges which are cut and renders them stiff and difficult to work. Its working qualities are preserved by excluding it as much as possible from the atmosphere, and when used it should be well annealed. When freshly made it is sufficiently cohesive for general use without annealing. Many operators rely upon it for starting and finishing all fillings, but there is no form of gold that is so well adapted for starting fillings in shallow and irregular superficial cavities as this. Crystal Mat or Solila Gold. — Several other forms of crystal gold have from time to time been introduced to the profession. That known as crystal mat or solila gold has found favor with some operators. It is manufactured by De Trey, and was first introduced in the United States in 1897. It is sold in the form of thick sheets or mats, and differs from sponge gold in that it is more compact in form and the crystals are smaller and matted together. It does not work as readily as the sponge gold, and breaks and crumbles under the plugger to a much greater degree, causing considerable waste. It possesses no good features which are not possessed by Watts' s crystal gold except that it is more plastic. Deep undercuts and retaining-pits are not necessary for the retention of this gold. Cavities having three or four walls may be prepared as for plastics. Hand-press- ure and broad- faced pluggers are best for working this gold. On account of its tendency to break and crumble under the j)lugger it is difficult to use it for contour work where a matrix cannot be used. In simple cavities and in approximal cavities where the matrix is admissible it makes a beautiful and serviceable filling and with little waste of material. In annealing this gold, it should never be heated to a cherry-red ; annealing just short of this point gives the best results. In starting the filling a large piece should be used, large enough to cover the bottom of the cavity, and this thoroughly condensed against the walls. Smaller pieces should be used in building the balance of the filling, care being taken to thoroughly condense each piece before another is added, Small instruments should be- used for condensing the filling against the enamel margins, as perfect adaptations cannot be secured with large pluggers. Operators who are accustomed to using non-cohesive foil will experience the least trouble in its manipulation, as the methods used in its introduc- tion and consolidation are quite similar. The ordinary methods should be followed in finishing and polishing the filling. Moss fibre gold, manufactured by the S. S. White Dental Manu^ facturing Company is the latest (1898) form of sponge gold that has been introduced to the profession. It is an exceedingly soft, tough, cohesive gold, and possesses these qualities in a much larger degree, perhaps, than any other sponge gold upon the market. It is easily adapted to the walls 270 OPERATIVE DENTISTRY. of the cavity, permits of extensive contouring, and when condensed pre- sents a hard, tongh surface, and takes a beautiful finish. Deej) undercuts or retaining-pits are not necessai-y in order to start a filling. The floor of the cavity should be as nearly flat as is possible, and the retentive shape given to it should be the same as for non-cohesive foil. Eound-faced pluggers with fine, shallow serrations, like the Eoyce instruments, are the best for packing and condensing this form of gold. Small pieces of gold only should be used. Large pieces cause bridging and result in a porous filling. In introducing the gold, each piece should be placed in the position required, and first ^'jjatted" with the plugger until evenly condensed, and then thoroughly condensed with hand-pressure or the mallet before another piece is added. Heavy malleting is not needed to condense this gold. Care must be exercised in annealing " moss fibre gold" not to overheat it. Under no circumstances should it be brought into contact with the flame of the lamp. Slightly warming the gold over a lamp upon a sheet of mica is all that is required. Overheating makes it hard and gives it a tendency to "ball" under the plugger. Extensive contour operations can be made with it more easily than with Watts's crystal gold. Gold-and-Platinum Foil. — This form of foil was first suggested by Moffet, of Boston, and is a combination of gold and platinum. It is made by '^ sweating" together an ingot of gold and one of platinum and then rolling to any thickness desired. ]N"o. 20 and No. 30 are the thicknesses generally made. It has the appearance of gold-foil before it is introduced into the cavity, but the condensing process brings out the color of the platinum. This form of gold was in great favor a few years ago for restoring the morsal edges and labial surfaces of incisor and cuspid teeth, and for fin- ishing fillings upon the morsal surfaces of bicuspids and molars. The advantages claimed for it over gold alone are its better, or, rather, less conspicuous color and its greater hardness. It is prepared for use by cutting the foil into narrow strips or ribbons, and after being freshly annealed it is welded to the gold filling in the same manner as heavy gold-foil. Especial 'care should be exercised, how- ever, in its introduction to see that each layer is thoroughly welded over its whole surface before another piece is added. Mallet force is superior to hand-pressure in its condensation, and round-faced foot-pluggers with fine serrations give the best results. On account of the stiffness of this form of foil it should be used only for the purposes just enumerated. To attempt to use it to fill the body of a cavity would only end in a disastrous failure, either by fracturing the walls of the cavity from the force necessary to condense it or from faulty adaptation to the walls and margins inviting secondary decay. Annealing Process. — All metals become more or less stiff and hard by the process of hammering and rolling. Gold-foil which has been made by either of these processes has, when it comes from the beater' s-skins or the rollers, lost its softness and ductility. To restore these qualities it becomes necessary to heat it. This process is termed annealing. The amount of heat used, and the length of time to which the foil is subjected TREATMENT OP CARIES BY OBTURATION, OR FILLING. 271 to it, will depend upon the degree of softness or of cohesiveness desired. All i^ure foil is rendered cohesive by annealing, but certain non-cohesive foils— those in which it is claimed iron has been used as an alloy — may be rendered soft and ductile by annealing without rendering them cohesive. Freshly made cohesive foil does not need to be reannealed except for con- tour work. Exposure to the atmosphere, however, soon renders it non- cohesive and makes reannealing necessary if contouring is contemplated. The alcohol flame or the gas flame from a Buusen burner are generally used for the purpose of annealing. Some operators hold the piece of foil in the flame, others hold it just above, thus heating it to the desired de- gree. Others use annealing trays made of mica, Eussia iron, or platiuum, which are held over the flame of the alcohol lamx^ or gas-jet. The latter method is the best, for the reason that it excludes the possibility of dele- terious substances like carbon, sulphur, or jDhosphorus being deposited upon the gold from the combustion of the lamx^-wick, or jDarticles of sul- phur or phosphorus which have been dropped uj^on the wick in igniting it with a match, or in the case of the Bunsen burner, from imperfect com- bustion of the gas, which might deposit carbon or sulphur. Fig. 394. Custer electric gold annealer. Fig. 395. Kerr electric gold annealer. Electric Annealing Tray. — The neatest and also the most satisfactory devices for annealing gold are the electric annealing tray of Custer, shown in Fig. 394, and that of Kerr, shown in Fig. 395. By these devices any degree of heat that may be desired can be obtained, and with a uniformity not possible with any other device or method. CHAPTEE XVIII. CONSIDERATIONS IN FILLING SPECIAL CS-ASSES OF CAVITIES. I. Simple Cavities upon Exposed Surfaces. — This class of cavities presents the most simple forms of fillings in the whole range of oi^erative procedures upon the teeth. Cavities which are situated, upon the lahial surfaces of Fig. 396. incisors and cuspids, especially when they have involved the cervix and extended beneath the margin o£ the gum, often present serious difficulties to the introduction of gold, which test the ingenuity, skill, and patience of the operator, as well as the fortitude of the i^atient. One of the most formidable difficulties to be overcome is the adjustment of the rubber dam to those cases in which the cavity extends beneath the free margin of the gum. This may sometimes be accomplished by passing a ligature around the cervix of the tooth and forcibly carrying it towards the apex, until the dam passes beyond the border of the cavity, or the gum may be held away by the aid of the gum retractor, shown in Fig. 396. It is always best to include in the rubber dam not only the tooth to be operated upon, but at least one u^Don either side of it. The How cervix clamp, shown in Fig. 397, often serves a good j)urpose in retaining the rubber dam in position, as do also the Libby clamp (Fig. 398), the Johnson lever clamp (Fig. 399), and the Dunn clamp (Figs. 400 and 401). Gum retractor (reduced). Fig. 397. Fig. 398. How cervix clamp. Libby clamp, It is sometimes necessary to slit the edge of the gum above the cavity in order to gain a clear view of the gingival margin and to permit the rubber dam to go above it. Cavities occurring in the labial surfaces of the incisors and cuspids are generally located either at the cervix or in the frequent imperfections of 272 CONSIDERATIONS IN FILLING SPECIAL CLASSES OF CAVITIES. 273 Fig. 399. the enamel, due to developmental defects. As a rule they are shallow, and therefore need to be given a good retentive form, either by slightly en- larging the cavity at the bottom or by forming small retaining-pits in the extremities. Cohesive foil or crystal gold are the best for filling this class of cavi- ties. The filling should be started in one of the ex- tremities, care being taken that the first piece of gold is securely anchored and the balance of the filling built upon this. Many operators finish such fillings with platinum-gold foil^ as the color is less conspicuous than pure gold. Figs. 402 and 403 show the location of fillings of this class. Cavities occurring upon the lingual surface of the incisors are generally confined to the laterals, and are the result of developmental defects, as shown in the imperfect closure of the pit or fissure at the base of the cingulum. These cavities are usually small, and are readily filled with a narrow ribbon of non-cohesive foil and finished with cohesive ; or the entire cavity Johnson lever clamp. may be filled with a narrow ribbon of cohesive foil, in Fig. 404. Such a filling is shown Fig. 400. Fig. 402. Fig. 403. Fig. 404. Caries rarely attacks the morsal edge of the incisors and cuspids, except as the result of imperfections in development, from mechanical abrasion, or from traumatic injuries which fracture the enamel. Consequently the operation of filling is usually confined to artificial cavities, made for the purpose of protecting the morsal edges against the loss of tooth-substance from mechanical or chemical abrasion, or for lengthening the teeth when it is desired to "open the bite." Cavities prepared for this purpose must have strong retentive form, as fillings of this class are constantly subjected to great stress. Many opera- 18 274 OPERATIVE DENTISTRY, tors are in tlie liabit of inserting a couple of "Mack" screws in tlie arti- ficially formed cavity, one near eacli extremity, as sliown in Fig. 405. These add very greatly to the retentive strength of the cavity and make it very difficult to dislodge such a filling. Care must be exercised in setting the screws not to encroach upon the pulp. Fig. 406. Fig. 405. Cohesive gold only should be used for building up these fillings. It may be either foil or crystal gold, as suits the fancy or the ability of the operator to manipulate one form of gold better than another. In making the choice he should always select that form of gold with which he is con- fident the best filling can be made. In starting the filling it is advisable to begin at one extremity of the cavity by anchoring the gold in the under- cut or retaining- pits, then repeat the process in the other extremity, and afterwards connect them together by a narrow ribbon laid upon the bottom of the cavity and folded back and forth, each fold being thoroughly con- densed upon the preceding one, care being taken to accurately fill the undercut before the building process is begun. Fillings in these locations must be thoroughly condensed with the mallet in order that they may obtain the greatest hardness possible to pure gold, as they are subjected to severe wear, which might result in abraded edges and flaking of the layers of gold. Fig. 406 shows the completed oi)eration. Platinum-gold in narrow ribbons of 'No. 20 or No. 30 is preferred by some operators for all of that part of the filling which extends beyond the walls of the retaining cavity. The Bonwill electric mallet or the engine mallet are invaluable for packing the gold in these cases. Cavities occurring in the fissures and sulci of the morsal surface of the Mcusjnds and molars are the most accessible, and from their location offer the least difficulty to the introduction of gold fillings. Such cavities, if prepared with perpendicular or slightly undercut walls, need no other retentive shaping to insure firm anchorage of the filling. These cavities can be most rapidly and substantially filled with non- cohesive foil ; in fact, this is one of the most favorable locations for the use of non-cohesive foil. The gold can be introduced in the form of narrow ribbons, small cylinders, or small spindle-shaped pellets. In introducing ribbons, one end should be grasped with the foil-pliers and carried to the bottom of the cavity, at that point which is farthest from the operator^ — this is a safe rule to follow in starting all classes of fillings, — and secured in place by a point held in the left hand, while with the pliers the ribbon is folded upon itself and carried again to the bottom of the cav- ity, and the fold packed firmly against its walls with a wedge-shaped or a foot-shaped plugger, but permitting the outer end of the ribbon to projed CONSIDERATIONS IN FILLING SPECIAL CLASSES OF CAVITIES. 275 a little beyond the walls of the cavity. A second ribbon is now introduced in the same manner and packed against the wall nearest the operator. A third ribbon is introduced in the same manner and packed against the two opposite uncovered walls, and the operation completed by driving ribbons of cohesive foil into the filling, and finishing with heavy foil. Or, cylin- FiG. 407. ders may be introduced instead of ribbons, placing them on end in the cav- ity and packing them against the walls, finishing in the centre with a hard- rolled pellet, and then thoroughly condensing the projecting ends of the cylinders. Or the spindle-shaped pellets may be used, the tip of one end of which should be annealed by passing it in the flame of the spirit-lamp, and the annealed ends allowed to project slightly beyond the walls of the cavity. These are packed against the walls of the cavity after the same manner as cylinders, the centre finally receiving a pellet of cohesive gold. The ends of the pellets which project beyond the walls of the cavity are then condensed, and the surface finished with mats of cohesive foil, which welds without flaw to the surface formed by the annealed ends of the pellets. By this method the danger of the surface of the filling scaling off is obviated. Scaling off of the surface of the filling often occurs when the union of the cohesive gold with the balance of the filling is only mechanical. All fillings upon the morsal surfaces of the teeth should be made as hard as possible by thorough but judicious malleting. Pig. 407 shows the finished fillings. In cavities of larger size and depth, requiring the cutting away of the triangular ridge, and in those involving more considerable portions of the morsal surface of the molars, but in which the walls are perpendicular and strong (Figs. 408 and 409), cylinders will be found to offer the most rapid and efficient means of introducing the filling. These should be packed Fig. 408. Fig. 409. solidly against the walls in all directions, and the central portion filled by inserting cylinders, one after another, as long as space can be made for one with heavy wedge-shaped pluggers. The protruding ends should next be thoroughly condensed, and the surfaces finished in the manner described above. In broad, shallow cavities, or those of uneven depth, cohesive foil is better adapted for the purpose than the non-cohesive. Such cavities need to be shaped with undercuts at opposite points, or retaining-pits or grooves at the bottom of the cavity, and so placed as to offer the greatest resistance to mechanical dislodgement. 276 OPERATIVE PENTISTRY, Tn the introduction of cohesive foil, the retain ing-pits or grooves are filled first, and the subsequent layers of gold welded to them and to each other. Cavities of uneven depth may be filled in the deepest portion with pellets of non-cohesive foil which have been rendered semi-cohesive at one end by annealing in the spirit-lamp, and the balance with ribbons, pellets, or mats of cohesive foil. In all deep cavities — those which approach very near to the pulp — this organ should be protected from thermal shock by the interposition of a layer of oxyphosphate cement or other suitable non- conducting medium. Cavities in the buccal surfaces of the bicuspids and molars are a little more inaccessible to operation than those of the class just described, and as a majority of these cavities are at the cervical border, difficulty is often experienced in adjusting the rubber dam so as to expose the cervical mar- gin of the cavity. The exclusion of moisture renders them but little more difficult to fill than those upon the morsal surfaces, except when located in the third molar, or when the patient's mouth is small, or the lips and cheeks are non-elastic. In deciding which form of gold shall be used in each individual case, the size and the depth of the cavity must be taken into consideration. Deep cavities are best filled with non-cohesive foil made into ribbons, cylinders, or pellets, and the surface finished with cohesive foil. Shallow cavities are always more easily filled with cohesive foil or crystal gold than with the non-cohesive. Watts' s crystal gold is most admirable for filling such cavities, as it requires but slight retentive shaping to obtain firm anchorage, and it does not possess the same tendency to "ball" or curl up at the edges and rock in the cavity as does cohesive foil. Especial attention should be given to the cervical margin in all those cavities which approach the gum line or extend beneath it. Non-cohesive foil will be more likely to insure a perfect sealing of the cavity at this point than cohesive foil by reason of its more ready adaptability. It is therefore advisable to place a thick mat or a large pellet of non-cohesive foil at the cervical margin, and make the balance of the filling with cohesive gold. Fig. 410 represents the finished filling. Cavities located upon the lingual surfaces of the bicuspids and molars are quite rare except in the lingual fissures of the superior molars. Occa- FiG. 410. Pilling in buccal surface of a bicuspid. sionally, however, they are found in teeth of defective development, and at the cervix and upon the roots of the teeth as a result of gingival reces- sion. Cavities of this class occurring in the inferior bicuspids and molars offer considerable difficulty to the introduction of gold fillings, and for this CONSIDERATIONS IN FILLING SPECIAL CLASSES OF CAVITIES. 277 reason plastics are more often used in these locations than any other filling- material. When they occur in the superior molars, gold can be more read- ily introduced, though by reason of the limited accessibility of the cavity it becomes necessary to use hand-pressure for the greater part, if not the whole, of the operation. The same method of filling as described for cavi- ties upon the buccal surfaces should be pursued in filling the accessible cavities of this class. II. Simple Approximal Cavities. — This class of cavities are those which are found upon the approximal surfaces of all the teeth, but which do not involve any other surface, and are bounded by a continuous and unbroken wall. Cavities of this class occurring upon the approximal surfaces of the incisors and cuspids generally require preliminary treatment by temporary separation, either by tape and wedges, or the more rapid method with the Perry or other screw separator. If the cavity is small and well within the labio- and linguo-mesial or distal angles, the case presents no difficul- ties other than those growing out of its degree of inaccessibility. Such cavities may be two-thirds filled with non-cohesive foil, cut in narrow rib- bons, and the balance with cohesive foil. Curved pluggers are necessary in filling these cavities, on account of the proximity of the adjoining teeth. In cavities which involve a considerable portion of the approximal sur- face, retention is secured at the cervical border by a groove at the base of the cavity, combined with a retaining-pit at the extremities, and by a shallow undercut at the morsal border. Grooving the labial or lingual walls for the purpose of retention is to be deprecated, as it tends to weaken them, and increases the liability to fracture and dislodgement of the filling. The dentist who possesses the spirit of the true artist will at all times endeavor to conceal the gold as much as possible when he is called upon to place it in the anterior teeth. Consequently he will, whenever possible, conserve the labial wall of these teeth. The filling should be started in one of the retaining-pits at the extremity of the groove made at the cervical border, then the pit in the opposite extremity should Fig. 412. be filled, and both united by attaching a ribbon of gold from one to the other, and malleting it into the retaining groove. This gives a firm foundation upon which to build the filling and secures thorough adaptation of the gold to the cervical wall. The balance of the filling is then completed after the manner already described in filling simple cavities. Cohesive gold, either foil or crystal gold, is best adapted for fillings of this character. Fig. 412 shows the completed filling. Simple api^roximal cavities in the mesial or distal surfaces of the bicuspids and molars offer considerably more difficulty in filling than similar cavities in the anterior teeth, by reason of their less accessible position. Tempo- rary separation is always necessary in those cases presenting a normal ap- proximation of the teeth. When the cavities are large it often becomes necessary, in order to gain a clear view of all parts of the cavity, to con- 278 OPERATIVE DENTISTRY. vert a simple into a compound one 5 or this procedure may be necessary on account of the extension of the disease in directions which undermine the enamel, making it too frail to bear the stress of mastication. Simple cavities in these locations may be filled after the manner de- scribed for filling similar cavities in the anterior teeth, with the excei)tion that by reason of their greater degree of inaccessibility hand-pressure becomes necessary in packing the gold for the greater i^art of the opera- tion. Non-cohesive foil can be used to advantage in this class of fillings if used in narrow ribbons, or loosely rolled cylinders or pellets, and the surface finished with cohesive foil. Some operators prefer cohesive gold throughout the operation. In such case the filling is started in small undercuts or pits made at the cervical border. The mallet is sometimes Fig. 414. Fig. 413. tiSed for condensing the surface, but it is less applicable to the distal sur- faces than to the mesial. Figs. 413 and 414 represent medium-sized fillings in thi approsimal surfaces of bicuspids and molars. in. Compound Cavities, — Compound cavities are those which in- volve two or more surfaces of the tooth, and, by reason of this, present the greatest difficulties in the operation of filling. Cavities which involve the mesio-ldbial and disto-lahial surfaces of the incisors and cuspids are the least difficult of the series to fill, from the fact that an unobstructed view can be obtained of every part of the cavity by direct light and unaided vision. Each portion of the cavity should be so shaped as to give it an iudei^endent retentive form. Cohesive foil is best for filling this class of cavities, as the welding property is valuable in binding the fillings together, giving to them a proper contour and a more highly finished surface. Foil cut in ribbons and freshly annealed or crystal gold should always be used in this class of cavities. In starting these fillings the general rule of beginning all fillings at the point farthest from the operator holds good. When the approximal cavity is about two thirds full the filling in the labial cavity should be started and connected with the approximal filling, and the whole then treated as one filling ; in this way both fillings are bound solidly together, and dislodgement is impossible except by fracturing the tooth. As these fillings (Fig. 415) are constantly exposed to view, the greatest pains should be taken to give them an artistic form and finish by restoring the natural contour of the tooth, avoiding peculiar marginal lines, and so finishing the surface of the gold as to make it as little conspicuous as possible. Mesio-lingual and disto-Ungual cavities in the incisors and cuspids may be filled (Fig. 416) in xDrecisely the same manner as those cavities last de- CONSIDERATIONS IN FILLING SPECIAL CLASSES OF CAVITIES. 279 scribed, care being taken that the retentive form of each cavity is such as to secure independent anchorage, and the gold so prepared that its welding property will be at its maximum degree. Cavities involving the mesio-morsal and disto-morsal surface of the incisors and cuspids are among the most dif&cult fillings to make substantial Fig. 415. Fig. 416. Fig. 417. by reason of their form and exposed position to stress and leverage (Fig. 417). The greatest care must therefore be exercised in securing firm an- chorage, and if this cannot be done within the formed cavity, it should be extended in some direction which will secure this without unnecessarily weakening the tooth. Figs. 418, 419, and 420 represent such methods of extension for anchor- age. In teeth having a broad morsal edge, additional anchorage may be secured by slightly grooving the labial and lingual walls at this point. Cohesive gold is best adapted to the requirements of such a filling, and used in such form as to preclude the possibility of the gold clogging under Fig. 420. Fig. 418. Fig. 419. (From Dental Cosmos.) the instrument, as air-spaces resulting from imperfect consolidation of the foil are an element of weakness in the filling. The filling should be started at the cervical border and built up from this point, keeping the surface of the gold as nearly flat as possible, and restoring the contour as the filling progresses, care being taken to secure perfect adaptation of the gold to the labial and lingual enamel margins. An electric or engine mallet greatly facilitates the rapidity of the opera- tion, and insures more perfect consolidation of the gold than can be obtained by hand-pressure or the hand-mallet without the expenditure of an infinite amount of time and labor. To guard against bruising or flaking of the morsal edge of the filling, thorough condensation of the gold must be secured. Heavy foil, No. 20 or No. 30, if each piece is thoroughly welded to the surface of the filling before another is added, will make the hardest surface obtainable with gold. 280 OPERATIVE DENTISTRY. Cavities which involve hoth approximal surfaces and the morsal edge of the incisors and cuspids — mesio-disto-morscd cavities — present the greatest difficulties from the mechanical stand-point in the whole range of opera- tions for restoring lost portions of tooth-structure with gold, but when the operation is finished it becomes, by reason of its form, one of the most secure fillings that it is possible to make. The filling may be started at the cervical border in the pits and grooves made for the purpose in either of the approximal cavities, preferably in that one which is farthest from the operator. Cohesive gold only is admis- sible in this class of fillings. The filling should be built "Fir 421 up from the cervical border as squarely as possible until the morsal edge is reached. The same method is then employed in the approximal cavity nearest to the oper- ator, and when the morsal edge is reached the fillings are united by carrying the gold across the morsal edge, and finally finished at the approximo-morsal angle nearest to the operator. Fig. 421 represents the completed filling. If the approxi- mal fillings have been securely anchored, the force applied upon their morsal extremities will have no tendency to dislodge them during the process of building the morsal edge, but if this j)reliminary step has not been properly taken, dislodgement is more than likely to occur before the operation is completed. Cavities involving the mesial and morsal surfaces — mesio-morsal — of the bicuspids and molars offer no difficulties which are not readily overcome. The only preliminary necessary for the preparation and filling of the cavity is the obtaining of such an amount of space by some of the methods of temporary separation as will enable the operator to gain a clear view of the cavity in all of its parts, and permit of the original form Fig. 422. ^f ^jie tooth being restored by the insertion of a contour filling, as illustrated in Fig. 422. Failures in this class of fillings are pi'one to occur at the cer- vical border from secondary caries, and this is often due either to imperfect preparation of this portion of the cavity, to bruising of the enamel margin while condensing the gold against it, or to imperfect adaptation of the gold to the cervical wall. The greatest care should therefore be exercised in the preparation of the cavity and the introduc- tion of the gold. The cervical margin may be protected against bruising and i)erfect adaptation of the gold to the tooth secured by introducing a non-cohesive soft-rolled cylinder and condensing it against the cerv^ical border. Many operators are in the habit of filling the cervical third of the cavity with non-cohesive cylinders and the balance with cohesive foil. Others prefer to fill the entire cavity with cohesive foil, using crystal gold at the cervical border to form the foundation of the filling, as on account of its great soft- ness it is easily placed and can be readily adapted to the walls of the cavity. A safe rule in all contour work is to extend the gold a little beyond the desired line of contour, in order that there may be opportunity for final CONSIDERATIONS IN FILLING SPECIAL CLASSES OF CAVITIES. 281 shaping and polisMng without destroying the artistic contour of the finished filling. Thorough condensation of the gold is an important factor in the stability of this class of fillings. Flow of gold fillings under stress is much less, as shown by Dr. Black, in fillings that had been thoroughly condensed and hardened by malleting than in those which had not been malleted. These fillings are subject to great stress, and therefore need to be thoroughly anchored in the morsal surface. Fig. 423 shows a method of anchorage obtained by extending some portion of the morsal cavity or by its natural form. Figs. 424 and 425 represent the method of " extension for prevention''^ suggested by Dr. Black for filling bicuspids and molars. This method so Fig. 423. Fig. 424. Fig. 425. exposes the margins of the fillings that they can be kept clean with the tooth-brush, and it effectually secures them against a recurrence of caries with ordinary care of the mouth, provided the operation has been properly performed. Cavities situated upon the distal and morsal surfaces of the bicuspids and molars unite to form disto-morsal cavities. These are no different from the class just described except in their location, which adds very much to the difficulties in filling. All fill- ings of this class have to be made by the aid of reflected light, wliile the progress of the operation is viewed from the reflected image in the mirror. When the cavities are located in the posterior part of the mouth, as, for instance, in the second molars the difficulties of obtaining unobstructed light and vision are considerably enhanced. The operation of filling may be greatly simplified by the adjustment of a suitable matrix, thus converting a complicated operation into a sim- ple one. If the cavity has been given a proper retentive form, grooves and retain- ing-pits will not be needed, and the filling may be started with non-cohe- sive cylinders, mats, or pellets, thoroughly condensed against the cervical border and the matrix, which must be firmly fixed in position. After the cervical third of the cavity has been filled with non-cohesive gold, the bal- ance can be completed with cohesive gold in the manner described in the preceding class. Cavities occurring upon the morsal and buccal surfaces unite to form morso-buccal cavities. This class of compound cavities is usually confined to the lower molars and the upper third molars. They can usually be given a good retentive shape without forming grooves or retaining-pits. In the deep cavities non-cohesive gold can be used for the base of the filling and then finished with cohesive foil or crystal gold. In the shallower cavities it is best to use cohesive gold throughout. These fillings (Fig. 426) are 282 OPERATIVE DENTISTRY. subjected to great stress and wear ; they should therefore, be made as solid and hard as possible, that they may not be dislodged or battered by the occlusion of the opposing tooth. Fig. 426. Fig. 427. Cavities involving the mortal and lingual surfaces are usually confined to fho, first and second superior molars. From the fact that these cavities are generally shallow, they should be filled throughout with cohesive gold. Their position makes them fairly easy of access. The morsal cavity is usually the deepest, and may be quite large, while the lingual cavity is narrow and shallow. In this case the morsal cavity being the largest should be filled first, the smaller cavity and the channel uniting them being filled by carrying ribbons of foil, which are first attached to the main filling, over into the channel and to the cervical extremity of the lingual cavity (Fig. 427). Cavities situated upon the mesial^ distal, and morsal surfaces of the bi- cuspids and molars, uniting to form mesio-disto-morsal cavities, are of not uncommon occurrence. These cavities might be filled by the methods de- scribed for filling the same class of cavities occurring in the incisors and cuspids. Such operations, however, may be greatly simplified when made in the bicuspids and molars by the adjustment of a matrix to the distal surface. The band-matrix is sometimes used, but this is not so satisfactory, as it obstructs the light and vision to a considerable extent. Non-cohesive gold can be used to good advantage in forming the base, while cohesive foil should be used for the bulk of the filling. Fig. 429. Fig. 428. The filling should be started with a large, soft-rolled cylinder placed at the disto- cervical border and malleted into place. Others may be added until the entire floor of the cavity and mesio-cervical border are well cov- ered, after which cohesive gold may be used to complete the filling (Fig. 428). When the buccal and lingual walls are frail and likely to fracture under the stress of mastication, the cusps may be cut away and the whole morsal surface restored with gold. This operation decreases the liability to frac- CONSIDERATIONS IN FILLING SPECIAL CLASSES OF CAVITIES. 283 ture and, if well done, restores the tooth to its original form and preserves it for many years of usefulness. (See Fig. 429.) MATRICES. In filling compound approximal cavities — disto-morsal — in bicuspids and molars with the various forms of crystal or sponge gold, the matrix will be found of great service, not only in simplifying the cavity but in securing a more perfect adaptation of the gold to the enamel margin, and by facilitating the operation. In fact, many operators utilize these instru- ments in filling all disto-morsal cavities in the posterior teeth, no matter what form of gold may be used. Their greatest value, however, lies in their use as just indicated, and in the introduction of plastic materials. In the introduction of gold into disto-morsal cavities in the posterior part of the mouth, it is impossible to use a straight instrument for packing the gold ; it therefore becomes necessary to curve or bend the shaft of the plugger near its point to suitable angles for reaching the various surfaces of the cavity ; consequently the force or impact applied to the shaft of the instrument by the hand or the mallet is not directly expended upon the gold at the point of the plugger, but is more or less dissipated by the elasticity of the steel at the curve or angle, and by the tendency of each impact to drive the gold out of the cavity in a distal direction. By the adjustment of a suitable matrix a compound cavity is converted into a simple one, and the matrix used as a wall against which the gold may be packed. Objections have been raised to the use of these devices on account of the difficulty experienced in giving a proper contour to the approximal surfaces, and of securing perfect adaptation of the gold to the enamel margins which are contiguous to the matrix. These objections are readily overcome by a proper preparation of the cavity margins, which leaves them strong and straight, the careful adjust- ment of the matrix, and the same degree of skill exercised in introducing and condensing the gold against the margins that would be used in other cavities. Several forms of matrices have been invented, all of them possessing more or less valuable features. The Jack matrices, shown in Fig. 430, are so shaped as to provide for contouring, and are made in pairs, adapted for use upon the right and left sides of the mouth respectively. These are held in place against the tooth to be filled by wooden wedges driven between the matrix and the adjoin- ing tooth, the wedges being first dipped in sandarach varnish to keep them from slipping ; or it may be held in position by some quick-setting oxy- phosphate cement. The matrix is applied by an especially designed forceps, which grasps them firmly, permitting easy adjustment and withdrawal. When the rubber dam is used, this should be first adjusted, and the matiix applied afterwards. The matrix, to fulfil the object of its placement, must be immovably fixed against the tooth to be filled. Motion of the matrix results in im- perfect adaptation of the filling to the walls and margins by reason of the difficulty in packing the gold against a shifting body. 284 OPERATIVE DENTISTRY. To overcome this difficulty, loo][} and hand matrices were devised of various forms and sizes to accord with the differences in the size of the Fig. 430. oo ot Jack matrices and forceps. teeth. The Brophy and the Guilford patterns are the best of their kind, and are easy to adjust, — these are shown in Figs. 431 and 432. The only difficulty experienced in the use of loop or band matrices is to obtain a close adjustment at the cervix of the tooth, by reason of the smaller size Fig. 431. Brophy band matrices. of the tooth at this location as compared with the morsal surface of the crown. This difficulty may be overcome by driving a wooden wedge between the band and the adjoining tooth at the cervix, as previously described. CONSIDERATIONS IN FILLING SPECIAL CLASSFS OF CAVITIES. 285 The Woodward matrix (Fig. 433) is also an ingenious device, and in some features superior to the others just described. It has the great ad- FiG. 432. Guilford matrices, and manner of adjustment. vantage of being readily adapted to the cervix of the tooth, and is main- tained in position by means of two set screws, which rest against the tooth opposite the approximal cavity to be filled and act as separators. Fig. 433. Woodward double-screw matrices. A.S the teeth move under the pressure of the screws, it becomes neces- sary to occasionally tighten them. The space thus gained is of great value during the process of finishing the filling. TIN-FOIL. Chemically pure tin is furnished to the dentist in three forms, — foil, fibrous mats, and rolled strips. Foil is the form most generally used. This is beaten after the same manner as gold, and is furnished to the pro- fession usually in two weights. No. 3 and No. 4, the figures representing 286 OPERATIVE DENTISTRY. the weight of the foil in grains. No. 3 foil is the weight in most general use. The Jiby'ous mats or ^''fibrous tin''' is made from fine shavings of tin loosely pressed into mats. This form of tin has a tendencj^ to crumble, and is therefore not so readily introduced into the cavity as foil, neither has it any advantages which are not possessed in an equal or higher degree by the foil. Boiled strips of tin are about the weight of No. 20 gold- foil, and are used in the same manner as ribbons of non-cohesive foil. Tin is one of the oldest filling-materials, and until the introduction of amalgam was the only substance at the disposal of the dentist for filling that class of teeth which were not considered worthy of the precious metal, or which for pecuniary reasons the patient could not afford to have filled with gold. It is much more ductile and easier of introduction than gold. It can be more readily adapted to frail cavity walls, and when properly intro- duced makes a perfectly moisture-tight plug. It does not readily oxidize, and but for its ohjectioiuible color and softness would be the very best mate- rial for filling frail teeth. Tin-foil when first made is cohesive to a certain degree, but this property is soon lost on being exposed to the atmosphere, and cannot be restored by annealing. The therapeutic action of tin upon tooth- structure is decidedly antiseptic when oxidation takes place. For this reason it cannot be too highly recom- mended for lining the cervical wall in approximal gold fillings, and as a filling-material in those cases in which there is a persistent recurrence of caries, associated with a thick, ropy, tenacious saliva, which in all proba- bility is due to the presence of gelatin-forming micro-organisms within the mouth. Tin does not conduct thermal changes so readily as gold, and conse- quently causes much less irritation to sensitive dentin. This fact led many of the older operators to line the bottom of all hypersensitive cavities, and those in which the pulp was nearly exposed, with a layer of tin-foil. Its most important use is for filling the temporary teeth and first perma- nent molars of children. The ease and rapidity with which it may be inserted and condensed, as well as its preservative qualities upon tooth- structure, make it the best material for this purpose that the dentist has at his command. TIN AND GOLD. Tin is also em]Dloyed in combination with gold-foil. The metals are combined in various proportions ; some operators enclose a sheet of No. 4 tin between two sheets of No. 4 gold-foil, and then either twist it into a rope or cut it into ribbons ; others fold a sheet of No. 3 tin in a sheet of No. 4 gold-foil, and then twist it into ropes of various sizes or cut it into ribbons of varying widths to suit the case in hand. The ropes may also be cut into pellets or the ribbons rolled into cylinders. This mixture of the metals works with about the same degree of soft- ness as tin alone, and can be as readily adapted to the walls of the cavity. CONSIDERATIONS IN FILLING SPECIAL CLASSES OF CAVITIES. 287 l^on-cohesive gold-foil is generally used in combination with tin, but some oj^erators use cohesive foil, and then cover the surface of the filling with gold, claiming by this combination they are able to weld the gold to the tin and gold base. Fillings which are made of tin and gold combined have a yellowish- gray api^earance when first finished, but they soon become more or less discolored upon the surface by oxidation. After a time some chemical change, which at present is not understood, takes place in the mass, rendering it exceedingly hard and giving it the appearance of an amalgam. It does not, however, stain the tooth-struc- ture, as might be expected, and seems to exert a very decided preventive effect upon caries. Such fillings will resist the attrition of mastication as well as gold, but they have the disadvantage of being unsightly in color, and should not therefore be placed in any conspicuous part of the mouth. Fillings made of this combination of metals do not conduct thermal changes so readily as gold alone, and consequently are better adapted to sensitive teeth. Such fillings are in every way superior to amalgam, and find their greatest field of usefulness in the bicuspids and molars during the periods of childhood and adolescence, and in persons subject to per- sistent caries. It can be introduced as rapidly as tin alone, makes a very durable fill- ing, and possesses a conserving action upon tooth -structure not possessed by gold alone or by amalgam. Methods of introducing Tin and Tin and Gold. — The methods of introducing fillings composed of tin and tin and gold, are the same as those used in introducing non-cohesive gold-foil. Some operators prefer to use cylinders and wedge-pointed pluggers and hand-pressure ; others use pellets and foot-shaped plnggers with the hand or mechanical mallet, finishing the filling by driving a hard-rolled pellet into the central por- tion of the plug, and then thoroughly condensing the surface towards the enamel margins with broad-faced pluggers and afterwards thoroughly burnishing. Fillings made from tin or tin and gold combined should be finished with the same degree of care and thoroughness as is expended upon those made from gold. The labor, however, is much less, as the material is not so resistant as gold. Finishing Fillings. — The beauty and the utility of gold fillings are greatly enhanced by perfect finishing. Fillings which have been well and carefully introduced sometimes fail for the reason that the margins have not been entirely freed from overhanging portions of gold, or the gold has not been cut down and finished flush with the enamel margins and highly polished. These imperfections are jnost often found at the cervical border of approximal fillings, particularly in the bicuspids and molars, where there is a tendency to bifurcation of the root, and the cavity extends beneath the gum, making a clear view of the cervical border very difficult to obtain. Fillings which present rough surfaces or imperfectly finished margins 288 OPERATIVE DENTISTRY. invite recurrence of caries, by reason of the fact that these imperfections give lodgement to alimentary debris, where if it remains undisturbed it is soon attacked by the zymogenic bacteria, lactic acid is formed, and sooner or later secondary caries is established. The importance, therefore, of perfectly finishing all fillings cannot be over-estimated if the best results are to be obtained. In order to secure a surface in a gold filling that will receive a fine finish thorough condensation is of the greatest importance. Fillings which are imperfectly condensed cannot be made to take a smooth and highly polished surface, while after a little time the surfaces exposed to wear will become rough and pitted. In order to insure a good surface that will finish smoothly, many oper- ators are in the habit of using heavy foils for the last few layers of the filling. After the surface has been thoroughly condensed the burnisher should be vigorously applied, especially to the margins, in order to obtain perfect contact of the gold at these lines and to secure a compact and hard surface. Hand-burnishers (Fig. 434) or those revolved by the dental engine may be used for this purpose. The latter are made of various shapes, some having smooth surfaces, others corrugated surfaces, as shown in Fig. 435. Fig. 434. 3 Hand-burnishers. In all fillings the cavity should be filled a trifle fuller than the margins of the surface in which they are located, that there may be opportunity for a proper shaping of the surface of the filling to harmonize with the normal lines of contour. CONSIDEEATIONS IN FILLING SPECIAL CLASSES OF CAVITIES. 289 This shaping or dressing of simple cavities in the morsal surface of the bicuspids and molars may be accomplished by finishing-burs, such as are Fig. 435. Engine-burnishers. shown in Figs. 436 and 437. The ^'cut'' of these burs is much finer than that of cavity burs, and gives the surface of the filling a finish similar to that given to a flat surface with a fine file. The gold should be cut away Fig. 436. Fig. 437. Disk burnishers. Flug-flnishing burs. until the margins of the cavity have been reached and all overlapping por- tions havebeen removed. The occlusion of the teeth should next be noted, and the surface of the filling made to conform to the occluding points or eminences of the morsal surface of the opposing teeth. As soon as a natural occlusion Is obtained the surface of the filling should be polished, using fine powdered pumice and water, with a suitable wood point, as shown in Fig. 438, mounted in an engine porte- carrier. If the operator desires to give a burnished surface to the filling, this may be accomplished with a suitable engine-burnisher, lubricated with a solution of fine toilet soap in water. Fig. 438, Wood polishing-points. Large fillings in the morsal surfaces may be cut down with suitable corundum points or wheels. These instruments cut much more rapidly than the finishing-burs, and if kept wet with a stream of water from the syringe cause but little heating of the tooth. Fig. 439 shows a few of the various forms of these points and wheels. The best cutting and also the most durable corundum points and wheels are those made of fine corundum and vulcanized rubber. 19 290 OPEEATIVE DENTISTRY, In the use of corundum points for dressing down the surfaces of fillings there is danger, from the rapidity with which they cut, of grinding the Fig. 439. Corundum points and wheels. edges of the cavity and thus producing a thin and weakened margin. A final finish may be given to the surface of the filling by smoothing with Fig. 440. "'■■"■"I"-" -I'A, Arkansas, Hindostan, and Scotch stones. Arkansas or Hindostan stones of similar shapes (Fig. 440) and polishing with pumice or the burnisher. Fig. 441. Labial and buccal surface fillings are most readily finished with the corundum points, followed by the Arkansas stones and wood points carrying moistened pumice. The beauty of fillings lies in their perfect mar- gins and natural contour. Any overlap- X)iug of the gold gives the appearance of a ragged edge, while any degree of deviation from the normal convexity of the surface detracts from their beauty of outline. The final polishing may be done with felt or leather polishing- wheels or soft rubber pol- ishiug-cups. The latter are especially valuable in finishing bucco- cervical fillings in bicuspids and labio-cervical fillings in the six anterior teeth. Soft rubber polishing-cups, corrugated inside. CONSIDERATIONS IN FILLING SPECIAL CLASSES OF CAVITIES. 291 They are sliown in Fig. 441. If a dead or satin finish is desired, — and this is best for the anterior portion of the mouth, because it is less conspicuous, — pumice moistened with water or glycerol will be found most satisfactory for this purpose, but if a brilliant finish is required, the pumice should be followed with precipitated chalk, oxide of tin, or rouge. Fillings which are located upon the approximal surfaces of the teeth are much more difiicult to finish than those in any other portion, and conse- quently require a higher order of skill, while for obvious reasons there is no class of fillings which demand greater care in their finishing, or which repay the operator a higher reward for faithful service rendered. Fig. 442. Plug-trimmers and plug-flnishing files. As a consequence of the difficulties encountered in finishing this class of fillings a great variety of instruments have been devised to overcome them. The oldest of these are the thin flat files cut only upon one side Fig. 443. Fig. 444. Approximal trimmer. and both edges. Some of them are made with a spring temper, straight and curved ; others are tempered soft, and may be given any desired curve to suit the exigencies of the case in hand. These are shown in Fig. 442 and are most useful in the anterior part of the mouth. For trimming the cervical margins of the filling, the approximal trimmer shown in Fig. 443 is one of the most useful instruments devised for this purpose. This is file-cut upon one or both faces, and should gen- erally be used with a drawing motion, the blades of | the file being set with that object in view. The sickle-shaped knife trimmers of Dr. Gordon "White, shown in Fig. 444 are also admirable instru- ments for trimming the cervical margins of fillings. On account of the difficulties experienced in get- ting a clear view of the field of operation, it becomes necessary to examine the cervical margin by passing a fine i^robe or explorer over this portion of the filling, or, better still, floss-silk may be made to pass back and forth, from the cervix to the Sickle-shaped trimmers. 292 OPERATIVE DENTISTRY. morsal border of the filling, and if the probe does not catch or the floss- silk becomes frayed in the process, it may be presumed that the over- lapping edges of the filling have all been removed. The final shaping of the filling may be accomplished by emery tape or sand-paper strips drawn back and forth over the surface of the filling. When the margins are all well defined, the finishing may be completed with finer emery, silex, or buckhorn tape. A variety of these strips should always be on hand, comprising all the grits from the coarsest to the finest. The final polishing may be done with the soft rubber cups or thin soft rubber wheels charged with fine j)umice. Approximal fillings in bicuspids and molars, because of the difficulties of access which are x^resented by their position, make them the most trouble- some of all fillings to finish. It therefore is necessary that the greatest care be exercised in this process, and that the cervical border receive par- ticular attention. Fillings which have been placed in those locations with- out the aid of a close-fitting matrix usually present a considerable over- lapping of the gold at the cervical border. The success of the filling, other things being equal, will depend largely upon the perfection with which the cervical margin is trimmed and finished. In those cases where a properly adjusted matrix has been used, the labor of trimming the margins and finishing the surface will be found to be greatly lessened. The pointed, right and left, curved files of Dr. Meriam, shown in Fig. 445, will greatly facilitate the work of removing the overlapping edges of Fig. 440. Dr. Meriam's right and left plug-finishing files. gold at the cervical margin, and, supplemented with the trimmers just mentioned, will enable the operator to give the desired form to the surface of the filling. The final finishing can be accomjplished with emery tape, sand-paper strips, etc., after the manner de- scribed above, or with emery cloth or sand- paper and cuttle-fish disks mounted upon suitable mandrels for use with the dental engine. These disks are made of various sizes, some of them having only a narrow rim of grit, the balance of the disk being plain (Fig. 446). The latter are valuable for polish- ing the cervical margin of contour approximal fillings, as it enables the operator to do this without cutting away the con- tour of the filling at the morsal border. Fig. 447 shows two of the popular forms of mandrels for carrying these disks. Thickened rim sand-paper disks. COXSIDERATIONS IN FILLING SPECIAL CLASSES OF CAVITIES. 293 Especial attention should also be given to the morsal surface of those approximal fillings which involve this surface of the tooth, that perfect occlusion may be secured. If the crushing stress of the jaws is expended upon such a filling, it is bound, sooner or later, to be dislodged, either Fig. 447. The Morgan-Maxfield disk mandrel. from the flow of the gold under stress, the disturbance of the anchorage, or from fracture of the walls of the cavity. Such surfaces should be so shaped that the filling will not be called upon to carry more of the load than the surrounding portions of the morsal surface of the crown or' of the other teeth. Fillings made of tin and tin and gold are finished in a similar manner. REPAIRING DEFECTIVE GOLD FILLINGS. Gold fillings which are defective from imperfect adaptation to an enamel margin, from recurrence of- caries, or from fracture, are often susceiDtible to rei)air. These cases many times present problems which are by no means easy to solve. In the consideration of the question, each case offers a peculiar condition which makes it necessary to treat it upon its individual needs. This consideration must take into account the nature of the defect, its location and accessibility, the condition of the remaining filling, and the material best suited for repairing the defective condition. Defects which are the result of imperfect adaptation to an enamel margin are usually discovered during the finishing of the filling, and if the rubber dam has not been removed, the defect may be readily repaired with cohesive gold. Sometimes it may be necessary to cut away the filling at the defec- tive point, forming a cavity in it of retentive shape. If the filling has been in contact with the saliva, the rubber dam must be adjusted, and the filling cleaned by bathing it with alcohol, ether, or chloroform, after which the defective point may be prepared as above, and filled with cohesive foil or crystal gold. Befects resulting from recurrence of caries are most often found at the cervical border of approximal fillings. Thorough separation of the teeth is necessary to successfully repair such defects. Defects of this character can often be repaired most efficiently by using non-cohesive foil cut in narrow ribbons, and packed into the cavity fold after fold, allowing the loops to project beyond the margins of the cavity, 294 OPERATIVE DENTJSTRY. and when the cavity is full, tliorouglily condensing tlie projecting loops and finisliing the filling with emery strips, etc., in the usual manner. If cohesive gold is used, a retentive shape must be given to the cavity, and a groove or pit provided for holding in place the first piece of gold. The bicuspids and molars offer the most difficult cases to repair, by reason of their inaccessibility. Gold is the best material with which to make such repairs, provided the cavity can be made accessible ; but some- times it is not possible to accomplish this except by removing the entire filling, and this, when the filling is large and otherwise good, seems unfair to the patient, if there is a reasonable assurance of making a successful repair with one of the plastics. Gutta-percha is often successfully used in these places, but occasionally it will be found to undergo decomposition, and is therefore not as reliable as gold. The oxyphosphate cements are contraindicated on account of their tendency to dissolve and wash out after a brief period. Amalgam is more often used than any other plastic for this purpose, on account of the readiness with which it can be intro- duced into cavities that are entirely inaccessible to gold, and the greater assurance of making a good repair. It has the disadvantage, however, of becoming very black after a few weeks of contact with the gold, but this does not lessen its value as a tooth preserver. On account of the black discoloration which always follows this use of amalgam, it should not be used in the anterior teeth. After the amalgam has become hard, it should be finished as carefully as possible, by removing all overlapping edges and polishing in the usual way. Defects caused from fracture of portions of the ca-^dty walls is a not in- frequent accident, and one which may be successfully repaired, provided the filling has been firmly anchored in other portions of the cavity and the tooth is sufficiently strong to warrant the necessary retentive shaping of the cavity to receive the repair. The incisors are prone to such accidents ; the most common being the loss of the mesio-inorsal or disto-morsal angle when large approximal fillings are situated well towards the morsal edge. Repairs of this kind are diffi- cult to make, but they may be successfully accomplished by taking ad- vantage of the favorable conditions that are presented. Each case must be carefully studied and treated according to the indications, '^o rule can be laid down for such cases. The operator must depend upon his knowl- edge of mechanics and his ingenuity to suggest a way to overcome the difiiculties of each case as it is presented. Anchorage may sometimes be secured by drilling a retain ing-pit in the filling at one angle, and another in the sound dentin at a different angle, or shallow retaining grooves or channels may be cut in the labial and lin- gual walls of the cavity and re-enforced by a pit drilled into the filling. Crystal gold will be found most serviceable in this class of operations. Accidents of this character sometimes occur in the bicuspids and the molars, most often in the bicuspids, especially when these teeth have been filled upon their mesial and distal surfaces, with the fillings uniting upon the morsal surface. The buccal or the lingual wall may be broken away CONSIDERATIONS IN FILLING SPECIAL CLASSES OF CAVITIES. 295 by stress so applied between the cusps as to split off tlie weaker of these walls. The prospect of successfully repairing these cases will depend ui)on the security of the anchorage of the ap proximal fillings, and the opportunity for obtaining good anchorage at the cervical border and laterally in the approximal fillings. When the buccal wall is lost it would be better prac- tice, for cosmetic reasons, to amputate the balance of the crown and place an artificial crown upon the root. If the lingual wall is lost, the objection to restoring it with gold is not so strong. Crystal gold gives the most satisfactory results in all cases of this character. Occasionally amalgam can be used for restoring the lingual cusps of a second bicuspid, but the discoloration which eventually follows makes this substance objectionable. Fractures of a similar character occurring in the molars are, as a rule, less difficult to repair, as they will usually admit of the proper retentive shaping without the same degree of danger to the pulp as accompanies the operation in the bicuspids. In those cases of fracture which extend beneath the gum, the difficulties are increased by the hemorrhage likely to attend the operation, and the difficulty experienced in retaining the rubber dam in a position beyond the fracture. . Mack's screws can sometimes be set in such position as to offer strong anchorage and not encroach upon the pulp. Under such circumstances they become a valuable adjunct to the other means of anchorage. Cohesive gold only can be used for such repairs, and the form usually indicated is Watts' s crystal gold. CHAPTEE XIX. PLASTIC riLLING-MATEEIALS. Definition. — Amalgam (from the Greek «//«, togetlier, and r«/^.^a, I marry), a combination of one or more metals with mercury. Amalgam. — The use of amalgam as a filling-material was first sug- gested in 1826 by M, Traveau, of Paris, under the name of "Silver Paste," and it was first introduced in the United States about the year 1830 by two Frenchmen named Crawcour, under the high-sounding title of the " Eoyal Mineral Succedaneum." It was a purely metallic comi^ound, com- posed of silver and copper, — " coin silver" (silver, nine i^arts ; copper, one part), — which had been reduced to a coarse powder by filing and rendered plastic by the addition of mercury. The mixture consisted of fifty per cent, of mercury, forty-five per cent, of silver, and five per cent, of copper. Fillings made of this compound soon turned almost a jet-black color upon the surface, and stained the tooth to an almost equally dark or dark-green shade by the formation of various compounds of silver and copper with oxygen and sulphur, which penetrated the tubuli and even the pulp-canal, the effect of which, however, seemed to place the dental tissues in a posi- tion to more or less successfully withstand the action of the direct causes of caries, as was seemingly proved by specimens of teeth which had been filled with it for many years without further decay. Some have thought this preservative action to be due to the formation of the sulphate of copper, which is an antiseptic of considerable value. In corroboration of this supposition the fact has been stated that when wood has been treated with solutions of sulphate of copper it is rendered much more enduring, as is known to civil engineers. It has also often been noticed in opening old tombs in England that in the oak cof&ns which had been put together with copper nails the wood immediately surrounding the nails was in a state of perfect preservation, while the balance of the timber had literally crumbled to dust from decay. The inference is therefore drawn that inasmuch as the sulphate of copper preserves the wood that has been treated with it, tooth-structure will also be preserved if the tubuli are impregnated with this salt, as it destroys the bacteria already in the tubuli and renders the dental tissues an unfavora- ble soil for the growth of the lactic-acid-producing bacteria. The merits and demerits of amalgam as a filling-material have furnished a ' ' bone of contention' ' over which the i)rofession has wrangled for years, and have been the cause of much heart-burning and bitterness. The strife and ill-feeling engendered between the contending parties ran so high at one time as to bring about a professional and almost a social ostracism of those who dared to advocate its use. The opponents of amalgam looked upon this material as an agent which was destined to degrade the profession and set at naught the achievements 296 PLASTIC FILLING-MATERIALS. 297 wliicli had been wrought with gold as a material for filling and saving teeth. It was a fact, also, in the earlier years of the amalgam controversy, that a large majority of those who used this material were men not worthy of the name of dentist, men who had not the skill to make a creditable oper- ation with gold ; hence the contempt in which they were held by the better class of practitioners. This contempt was also heaped upon the material which had formed the basis of the controversy. A few, however, of the better class of practitioners, who had a scientific turn of mind, began an investigation into the merits and demerits of this material from the stand- point of science, and finally succeeded in clearing away much of error and misstatement upon both sides of the cxuestion. As a result of this labor, the iDrejudice which was at that time so strong has of late years been gradually dying out, while to-day many of those who were among its bitterest enemies admit that under certain circum- stances and pathologic conditions, amalgam has proved itself to be a very valuable adjunct to the armamentarium of the dentist for saving teeth. Since the first introduction of amalgam as a filling-material many im- provements have been made in its composition and in the methods of its manipulation. To the New Dejmrture Triumvirate, Flagg, Chase, and Palmer, belongs the credit of placing amalgam upon a scientific basis as a filling-material, although the earlier efforts of Townsend, Walker, and Arrington to perfect this material by eliminating the main objectionable feature of discoloration should not be forgotten. Townsend, recognizing the one great demerit of the old form of amal- gam, introduced in 1855, after a long series of experiments, an alloy com- posed of forty-four and one-half i)arts of pure silver and fifty-five and one-half parts of pure tin. The progress gained by this formula was, however, very doubtful, although .there was a marked improvement in the tendency to discoloration. This feature was more than counterbalanced by its greater degree of shrinkage, which caused leakage and secondary decay. The formula forty parts of silver and sixty parts of tin formed the basis of all the various alloys that were introduced to the profession from the time of Townsend until the ISTew Departure Triumvirate gave to the profession the results of its researches into the nature and physical prop- erties of amalgams and other plastic filling-materials. These studies re- sulted in a radical change in the composition of the alloys used in making amalgams. The amount of silver was increased and the tin decreased, the ho^ic formula being sixty parts of silver to forty parts of tin. The introduction of more scientific methods in the manufacture, prep- aration, and manijDulation of amalgam and the other plastic filling-mate- rials has greatly increased their usefulness as therapeutic agents, and made it possible for the i)Oor, by a limited expenditure of money, to have their teeth cared for and saved for years of comfort and usefulness, while, upon the other hand, the more exact knowledge gained of the nature of their 298 OPERATIVE DENTISTRY. physical, chemical, and therapeutic properties has made it possible to apply them to particular pathologic conditions with a reasonable assurance that they will fulfil the requirements of the individual state or condition for which they were applied. THE NATURE AND PROPERTIES OF AMALGAM. One or more metals held in combination with mercury is termed an amalgam. Two or more metals combined by melting are termed an alloy. No combination of metals can be called an amalgam until they have been combined with mercury ; hence the combinations of metals used for the purpose of making an amalgam should be termed dental alloys, and not amalgams. No mixture or combination of metals can be regarded as an amalgam unless it has mercury as one of its component parts, and that ^ ' in sufficient quantity to exert a combining influence over the other metals." (Flagg.) Amalgams are classified according to the number of metals which they contain. Those containing two metals — as, for instance, copper and mer- cury — are termed binary ; those containing two metals in combination with mercury are termed ternary ; those containing three in combination with mercury are known as quaternary amalgams. Mercury has the property of dissolving or melting certain other metals of a higher fusing character. '■ ' The combinations thus formed are in the case of solid amalgams definite compounds, but in which there is only a feeble chemical affinity between the constituents. Liquid amalgams are merely solutions of the various metals in mercury, and not, as a rule, definite chemical compounds." (Watts.) Amalgams, however, may with correctness be classed as alloys. Mat- th lessen has suggested that "an alloy may be either (1) a solution of one metal in another, (2) a chemical combination, (3) a mechanical mixture, or (4) a solution or mixture of two or all of the foregoing." Kirk is of the oi^inion that in combijiing mercury with dental alloys a chemical combination is, formed. He says, "In all amalgams which possess the quality of setting or hardening from a plastic mass, we have to deal almost certainly with a chemical combination. The property of setting is in itself an evidence of chemical combination, and the formation of many amalgams is attended with elevation of temperature, more or less- marked, which is another indication of chemical combination. Changes of the volume of the mass attendant upon the act of setting still further indicate that chemical union of some portion of the constituent elements of the amalgam has taken jjlace." The Physical Properties of Amalgam. — The peculiar i)hysical properties of amalgams are, — viz., setting, contraction, expansion, flow, stability, color, conductivity. Setting. — Du Bois says, " Our present theory in regard to the forma- tion of an amalgam is, that metals which melt at comparatively high tem- peratures when brought under the fusing influence of mercury — which re- mains liquid at a temperature of —30° F.— are melted into union with it." The setting, hardening, or crystallizing of the mass is therefore due to the PLASTIC FILLING-MATERIALS. 299 secondary cooling effect exerted upon the mercury by the admixture of those metals which possess a high fusing-point, and that the higher the fusing- point of the metals amalgamated, the more rapid will be the process of setting. Platinum, however, presents an exception to this rule. Amalgams are decomposed by the application of heat sufficient to volatilize the mercury which holds the other metals in combination. During the process of setting, and for some time thereafter, nearly all amalgams undergo a change in volume and form. This change in volume may be either a contraction or an expansion. Contraction and Expansion. — Contraction, or "shrinking," and ex- pansion, or "bulging," of amalgams is, according to Flagg, in a general way in harmony with the natural contraction or expansion of the metals composing it, when passing from a fluid to a solid state. Those metals which lose their fluidity slowly, like tin, for instance, cause the greatest amount of contraction, while metals like gold and copper, which lose their fluidity quickly, and silver, which expands when passing from the fluid to the solid state, exert a controlling influence upon contraction. The contraction of an amalgam filling produces "cupping of the sur- face and a drawing away of the mass from the walls of the cavity, while exxmnsion of an amalgam produces bulging of the surface. Black has shown, in his studies upon the "Physical Character of Amal- gams, ' ' etc. {Dental Cosmos, 1895), that contraction and expansion of dental amalgams are influenced by many factors, — viz. : " (1) To the composition of the alloy. " (2) To the fineness of the cut of the alloy. " (3) To the amount of mercury used in amalgamation. " (4) To the evenness with which the mercury is distributed. "(5) To the method of manipulation." Dental alloys which are composed of silver and tin — the tin in excess of the silver — contract very considerably during the process of setting, Avhile in those containing silver in excess the contraction is notably lessened. The proportions of these metals which will produce an amalgam with the mini- mum amount of contraction has been demonstrated by Flagg, and later by Black, to be silver sixty-five per cent., tin thirty-five per cent. Ee- ducing the amount of silver and increasing the tin produces an alloy which will form a contracting amalgam, while increasing the silver and decreasing the tin produces an expanding amalgam. Black in his experiments found that in all silver-tin amalgams in which the percentage of silver was below sixty per cent, contraction was the rule, the amount of contraction seemingly being governed by the relative proportions of the silver and tin contained in the alio}'. He also found that contraction occurred during the first twenty-four hours, being greatest during the first two hours. A slight compensating expansion then occurred, lasting for from one to three days. During the process of expansion the amalgam softens very materially. This process he thinks is normal to all amalgams containing less than sixty per cent, of silver, as its absence is the exception. Slight contraction again follows the expansion, and this he thinks extends over an indefinite period. 300 OPERATIVE DENTISTRV. In alloys containing more than sixty per cent, of silver there is no primary contraction, while iu those containing eighty per cent, of silver and twenty per cent, of tin the expansion was very great, causing bulging or " spheroiding" of the surface of the filling. This condition was always notably present in the old, coin silver amalgam, which contained ninety per cent, of silver. The fineness of the cut of the alloys, also, seems to exert an influence upon the contraction and expansion of amalgams containing fifty to sixty per cent, of silver, for Black found alloys of the same grade or composition, if cut fine or comminuted into very fine particles, always contracted much more than when cut in moderately coarse' filings. This was a constant condition with this grade of amalgam. He was unable to definitely ex- plain this condition, but states the facts that the reduction of the alloy to such fine particles causes them to take up more mercury, and that the re- sulting amalgam is much softer and contraction greater. The percentage of mercury contained in amalgam influences the con- traction and expansion to a greater or less degree. Black says, however, that it "is not so important a factor in the contraction of amalgam as he had supposed, and yet when the mass has been worked very dry the change of bulk has been markedly less, whether contraction or expansion." An excess of mercury in contracting amalgams increases the contraction, while in expanding amalgams it increases the expansion. He found that " soft fillings, or fillings made from a mass containing fifty per cent, or more of mercury, showed great irregularity in contrac- tion." This author also found that a difference of five per cent, of mercury, or even more, in the fifty to sixty per cent, silver alloys, did not materially affect the contraction, but when the mass was so dry that no mercury could be worked to the surface in the process of packing it into the cavity, there was a marked lessening of the contraction. The amount of mercury required to amalgamate the different alloys depends largely upon the per cent, of silver which they contain. This fact has long been recognized. Black found that the increase of mercury to form a workable mass was not very noticeable until the amount of silver passed beyond sixty-five per cent. ; but with seventy per cent, silver alloys it became very difficult to amalgamate them with fifty per cent, of mercury j while with eighty per cent, of silver, sixty per cent, of mercury was necessary to form a work- able amalgam. The increase in expansion became very notable with the increase in the percentage of mercury. He also discovered that an increase of mercury was necessary for com- plete amalgamation of those alloys which contained less than sixty per cent, of silver, though this increase was much less marked. Alloys which contain sixty per cent, of silver require less mercury to form a good workable mass than those containing any other proportion. These facts, and many others, are most graphically shown in the accom- panying table or exhibit of Dr. Black, "On the Contraction and ExpauwSion of Amalgrams." PLASTIC FILLING-MATERIALS. 301 -r—[ r-r T-l n — 1 rr — r ■- -r| — ■""" _ - — - -TT — ■" 1 1 1 < 1 ( 1 1 I i 1 \ • < » > 1 1 1 t n ■ i ' 1 1 <6 ' pi 1 ' 1 1 1 1 ' 1 ■ i ' 1 i 1 ■ ' ^ 1 ' 1 H 1 ll ', y 1 1 ( 4 * ( 1 ^ 1 < 1 ' ' 1 U ' 1 , ' " , , j ' 1 ■■ 1 i 1 ■ 1^< 1 J i ' ■ ■ 41 ! ' / ■ t fi - r- / ^ .•" ' ' / ■" , , ' 1 ■ < *f < 1 ^- A !- 1 " 1 N " ^I '^l VO K =0 Oi ^ «^ '6 0) a o M '6 a S 1 '6 O a ° e a s s & % £> i I a; o a) 1 §^ ^.2 M ' 0)* O ^ o 1 i.. !•■ -d c c3 W ) a \ 3 s a ^ \ 1 1 3 bJO C d 1 m O m ^ u d P< .^ a §• S ■& o -^ 302 OPERATIVE DENTISTRY. c w rn 1 — — — "T- - — - - - — ~ T~ F "H" ^ — " c ■^ I .. _ _ _. -_ — — _ - - — -- - - -- - - « - - -- \-, _J_ - - — - — - -- - - "" "~ ~ ~ ~ • 1 <- 2 1 1 1 < ' f ,. 1 1 _^ _ I •_ _ 1 ' _ _ _ ' 1 ' _ ' ' —1 _ _^ -; i ^ !0 ; ' ^ _ ' . _ _ < 1 _ _ _ ^ 1 1 1 ' ' , 1 \ 1 < ' ' i t ( ^ ^ 1 i ( r ' ' 'il \ 1 1 1 1 > 1 ' 1 J ' ^ \ '[ ; I 1 * i ' 1 ( _ _ V _ _ _ _ L _ 1 7 (1 ' n^ 1 1 ' 1 1 f ~ ~ J \ ■ ( f 1 * - ' ♦ 1 ^ \ 1 ^ { ;' fe 1 / / ^'- _ _ _ e J' > / ji W 1 ; y « N < < i " . ^ >s " "> * *o ^O ^ OO (TJ ^ k 0) •1-1 a o 1 '6 a M o s •6 a ■A '6 n3 G ■d a W 00 o o IN CO to CO CO a CO a. 1 o I \ c 00 o 1 P c o o e -d C 1 cS '% lO J a i ^ I. t i 1 i ^ PL, c s e ■so 1 c 1 % s s g e e • « • -S' \ % 1 1 \ i Q J: r 11 00 •fc. a a, c a 1 to o ei S p s S -, S 1 g ^ 1 < I c t3 CO o ■ 50 ; ci : i • "2 : s : p ^ S i a, - >s PLASTIC FILLING-MATEEIALS. 303 ~ ~ - 1 ~ ■"■ ■"■ TT ■ — 1' 1 " — " — r- ■| ( 1 1 j 1 t • "-HH } 1 M 1 9 f « a < -n 11 ' - i ( . ~ + • - * I • ( "rn < «' 1 1 . , m __ ( ■ ' > > 5 ^ « ■« Vj V ^ •n ' 1 1 i 1 ■"n~i J L 1 .!l.| . ' f T 1 f ' ' ' '\ f 1 1 (1 * ' i 1 1 y « ,, \ k [7 \ \ -f L \ 1 ^t r X \ \ ( f r" ^ i 1 1 \ ( > " V (f T% / r 1 1 1 * ^' 1 / ' 1 V~ J 'ir ^-^ i ^ i > / A ^' \ ^^ ^ A ^ -' ' ►" s i ■ r '^r i »^ M ItJ ^ ^ 0) M 1 •6 a W i a c3 -d a OS W i 1 '6 c S 3 §5 10 CO CO DO d ft d ft d ft a cohHPh d ft Ol CO Tl< CO Tf rH d d d i 5 ti C 3 S nog CO H S S S d - - (M C-l 1 o a I e c ■. 1 i 1 4i g ■d a > .s CS ■tJ k< g 1 p s si g s 1 1 c C ■p S oT i u ,0 i >> 5 !>>> 3S S S 3 c ^ 1 t 1 I c c c f c p- 3 3 3 1 1 ^ ' 1 1 i a 1 ■S 1 "5 ■G a a (P a 1 c 1 c a a % '3 3 M 1 1 g S 1 ■i 1 1 ■ •§ : S : ^ : ■« ; s • s : . e : "3 : 6 s 1 304 OPERATIVE DENTISTRY. C o 5 p r- -r- JT T- 17 T— rr r —r ■~ " MM. ■ "■ " — '■ — ■" — ~ - 1- * _ _ _ . _^ 1 • 1 i 1 ■ T . 1 • a ' 1 ' i. to > ' [j ' ' < 1 .'. 1 1 I ' ' 1 ' - ; . 1 / f - ; - ' V 1 H ; ' ' 1 ' ' 1 ' *< 1 ' ' ■ ' » ' M J ;_ ' ■ 1 4 / --r 1 j) 1 \ i I 1 :o_ \ ^ / M / ' ' / / / ' > I H 1 , ( ( 1 4 K M <^ T) >0 p 1 C-l CO s rH rH - cc o 12; to c o -c c 03 0) C o t-l •2 .^a tD S si a- s ^ 1 C 1 bi P i u o ■d P L-i 5? 1 .3 1 o 1 1 • 1 ! S : si, : ^ : °5 '■ d i 1 I ! c a 'I •s 1 i £ 1 1 S •o e fa's, i| 1 p £ ft a ■l 1 a P £ ,P o o a ^ e3 -P 0) !i 1 -c a; 0- fc; «: P J £| P.£ -d 1 1. s 1 1 a t C I a ,:: C c 1 c a C X 5 ■«" j 1 01 p 1 ft i w 1 e 1 PLASTIC FILLING-MATERIALS. ^05 i 5 ■"■ ~" ■ p "T- — p p - p p p - IT p p -pr -p p m ~ 1 1 ... "■ ■~ 1 P ^r '> Jk ■" " ~" ~^ -A 1 ~ 5 5 >0 "2 ■O / ' .n — ~ 1 - \ ~ ~ - — ?"* i -- 'Ti -- K 3 - -- :" : E z = = ; -b :-; ~ : -- ::: ;: : : 1 Si N [- -- - b: t ^ ^^ - •z - li. ^~ ~ - -- - - 's" -- - - ~z N ^ ^ N \ ^ V V ~ N 1 s If J_ ._ -., , 1± s j »• 1 »< . . . " u CO Oi s ;i a 1 •6 is S -* g ^ S 8 a 1 OiOO a ft d ft SB MHO d S >o CO 1 a Qi g ho a 'p- o 0) C ? o a 1 o |e s 3 W 1 f a a> O be p O a c3 o I bo C o ^^ ^a H S 1 1 w s 1 1 '§ •6 s g 1 a s5 ■a ^ 1 20 306 OPERATIVE DENTISTRY. Tt will be noticed by a reference to this exhibit that formula 'Ro. 1— silver 65, tin 35, mercury 44.60, mixed in the hand— gave the best results, there being no change in volume by either contraction or expansion at the sixth day. The evenness with ivhich the mercury is distributed through the mass appears to be a controlling factor in the contraction and expansion of amalgams. This investigator found that wringing or compressing the mass in a piece of linen or chamois-skin had the effect of improving the amalgam both in its working qualities and in the stability of the final product, independently of the removal of an excess of mercury, especially if the compression is maintained for a little time. This he found to be the case when the amal- gam was so dry that no mercury could be squeezed out of it, and suggests that the steady compression has the effect of producing an even distribu- tion of the mercury through the whole mass. The method of manipulation was also found by Black to be an important factor in controlling contraction in contracting amalgams and in obtaining good margins. In packing amalgams, he recommends that it should be introduced layer by layer, and the pressure so applied as to thoroughly condense the mass, without breaking it up or kneading it, and the softened material cut away with sharp spoon-shaped excavators before another layer is added, this process to be repeated until the cavity is full and a fine hard surface remains. To obtain good margins, the mass should be carefully compressed against the walls with a small instrument, but in such a way as not to break up the integrity of the partially packed material. Floiv of amalgams, — change of mass from molecular motion under stress. This is a property which has been observed to be possessed by the majority of metals, and described as the Jloiv of solids, but hitherto entirely unsus- pected as a property of amalgams until Black discovered it. In the ' ' flow" of metals, iron, steel, gold, silver, etc., except tin and a few of the softer metals, a given stress will cause the metal to yield, spread, or flow. The phenomena occur immediately, and cease after a period of from one to two minutes after the stress is applied, even though the stress be maintained. The application of greater stress causes an increased flow, which again ceases until still greater stress is applied. Black has discovered that the flow of dental amalgams is very different from this. He says, ' ' When the flow of amalgam has begun, it continues so long as stress is maintained. No increase of the stress is required to maintain the flow, even after the area of the amalgam has been greatly increased by the flattening of the mass between plain surfaces. If a stress of fifty pounds be put upon a block of amalgam one-tenth of an inch square, and maintained for one hour, flow will occur at a certain rate ; if the stress is reduced to twenty-five pounds, the flow will continue, but at a reduced rate. There is a manifest disposition of the material to creep out from under a load. It will go slowly with a light stress, somewhat quicker with a heavier one, but it cannot be made to go very quickly with a very heavy stress ; but will instead break into fragments." This investigator also discovered that there was a vast difference in the strength of amalgams under stress. PLASTIC FILLING-MATERIAI.S. 307 Exhibit of the Physical Properties of Silver-Tix Amalgams. 5'^ p "^ o £53 4 33.26 1 1 30.90 35.77 4 2.91 4 4.82 2 2 5.07 8.32 2 5.82 6 4.89 6 5 5 8.61 9.00 9.76 3 2.44 1 1 1.89 4.10 4 7.57 1 1 4 1 1 5.12 6.56 11.75 6.72 9.33 3 26.55 1 1 3 1 1 20.49 22.95 30.65 31.97 40.16 3 25.64 1 1 22.76 26.23 3 26.28 1 1 15.78 28.70 3 19.81 1 1 4 15.57 24.59 25.14 3 27.59 3 2 34.91 36.11 A mechanical mix of precipitates of the metals. Materials fur- nished by Dr. Ames, of Chicago Pressed in with serrated points, re- moving no mercury Burnished in ". Weighed and mixed and used without wringing out; fillings made at once Fillings made after forty minutes Made with hot instruments, after fifty minutes As the blocks were made the odd numbers were placed in one box and the even numbers in another, so that they should be alike, and the tests made two days apart. Pressed in Burnished in. Pressed in. . . Burnished in Pressed in... Burnished in Pressed in . . . Burnished in Pressed in.. . Burnished in Pressed in Burnished in. Pressed in Burnished in. Pressed in Burnislied in. Made with hot points. f Silver 60 \ Tin 40 / Silver 60 t Tin 40 .45 \ .55/ 42.45 57 53.22 45.88 0.45 0.45 f Silver ITin f Silver J. Tin (Copper f Silver J Tin ] Copper [Bismuth (Silver -^Tin (Gold Silver 60 ) Tin 37 y Gold 3 j Silver 48.5 Tin 48.5 Platinum 3.0 Silver 44.81 Tin 52.78 Gold 1.87 Platinum 0.62 Silver 54.86') Tin 44.89 V Zinc 0.25 j .55.61 55.61 38.58 41.04 40.00 40.00 40.00 40. .59 40.59 39.05 39.05 32.66 32.66 32.66 39.08 39.08 39.08 38,71 38.71 38.71 31.92 31.92 31.92 40.18 40.18 40.18 30.31 30.31 26.47 26.47 37.45 37.45 37.45 36.75 40.65 40.65 Mortar Mortar Mortar Hand Mortar Hand Hand Hand Hand Mortar Mortar Hand Hand Hand Hand Mortar Mortar Mortar Hand Hand Hand Mortar Mortar Mortar Hand Hand Hand Hand Hand Hand Hand Hand Hand Mortar Mortar Mortar 160 277 255 250 2.50 230 230 235 220 315 253 257 210 225 225 225 308 OPERATIVE DENTISTRY. Exhibit of tmk Physical Properties op Silver-Tin Amai.gams.— Continued. t- xn u u > i. o S tIo ^ o "oo 0) a •^s S ^ Notes. No. Formulae. 2 h C 0) ? ^5 o 5.5 Ph W p 12; < Ch r Silver 54.861 11 I Tin 1 Zinc 44.89 1 0.25 f 40.89 Hand 2 3 26.92 2.50 [Palladium 0.25 J | AladG witli liot points 11 11 ' 40.89 40.61 Hand Mortar 2 2 2 3 19.. 55 14.96 260 11 1' .33.01 Hand 2 4 16.34 275 11 ■ Silver Tin 41.92] 56.33 1 36.29 Mortar 2 4 22.44 252 12 ■ Platinum Zinc Bismuth 0.44 >■ 0.8S 0.44 J 38.46 Hand 3 3 16.53 207 Pacljed lightly, without removing any mercurv 12 « 41.43 Hand 3 3 11..33 195 Packed heavily with small points, removing all" mercury possible. . 12 " 41.43 Hand 3 3 19.92 Mixed without wringing out and packed lightly without remov- ing any mercury 12 f Silver 47.061 .50.00 Hand 3 3 11.26 160 Pressed in 13 J Tin 51.70 1 41.00 Hand 2 3 25.09 235 Burnished in 13 1 Cotrner 0.94 f [Zinc 0.24 J " 38.74 Mortar 2 3 24.48 237 Silver 42.83] 51.62 Tin 14 - Copper 4.65 y 35.95 Hand 2 3 14.22 220 Aluminum 0.55 | Gold 0.01 J Pressed in 14 " 35.95 Hand 4 1 4.09 Burnished in 14 " .35.95 Hand 4 1 8.13 14 " 31.15 Mortar 2 3 28.44 200 14 " 31.15 Mortar 4 1 16.40 14 " 31.15 Mortar 4 1 17.50 Experimental alloys made by Dr. P. ,1. Kester, of Chicago, espe- cially for investigation 1.5 J Silver JTin 70 1 30 J 50.00 Hand 2 4 4.28 300 (No mercury could be removed 15 „ 50.00 Mortar 2 3 4.12 345 from these mixes by wringing through muslin.) 15 " 50.00 Mortar 5 3 5.71 360 (With 50 per cent, of mercury 16 f Silver ITin 80 ■( 20 ; 50.00 Hand 2 4 7.41 275 the mix was a dark, semi-coheren't powder that was extremely diffi- 16 " 50.00 Mortar 2 3 9.23 280 cult to pack.) 16 " 60.00 Hand 2 3 2.40 330 (These mixes worked easily and 16 " 60.00 Hand 5 3 8.50 340 well, only that they set very 16 " 60.00 Mortar 2 3 4.24 315 quickly.) 16 ** 1 60.00 Mortar 5 3 4.50 325 Note. — In the above experimental alloys the increase of mercury required as the tin is diminished is very notable. It shows that after a certain point, n.ot yet accurately determiiied, we cannot diminish the flow by diminishing the percentage of tin. The foregoing table gives the iiow, crushing stress, etc., of a series of experiments conducted by Dr. Black with sixteen different formulae for dental amalgams. The flow of jDure silver-tin alloj^s was found to range from two and one- "half per cent, to ten per cent, under a stress of sixty pounds, the differ- ence depending upon the composition of the alloy, the fineness of the cut, and the special mode of manipulation. The silver-tin formulae ranged in composition from forty per cent, of silver and sixty per cent, of tin to sixty per cent, of silver and forty per PLASTIC FILLING-MATERIALS. 309 cent, of tin. The addition of a small per cent, of copper had a tendency to somewhat diminish the flow and give greater strength under stress. All other metals which enter into the composition of dental alloys mark- edly increase the flow of the amalgam^ but do not seem to materially injure the strength of the amalgam under stress. He thinks, however, that the crushing strength of an amalgam is not a test of its stability under stress, but looks upon the amount of floio as the important test. The great difficulty with the silver-tin amalgams is that they will gradually change in form under the stress of mastication, as was demonstrated in the laboratory ex- periments by subjecting specimens of hardened amalgam to an intermittent stress. The copper amalgams do not flow under stress, and the margins remain perfect. This was not the case with the silver-tin amalgams. Their disposi- tion to flow under the stress of mastication allows them to move in the cavity, and on account of this movement they do not retain perfect mar- gins, and thus, after a time, the way is opened for the establishment of secondary caries by reason of the re-entrance of the active agents of the disease. A careful study of the table in reference to the relative influence of the various metals entering into the com]30sitiou of dental alloys upon the flow of amalgams will be found to be exceedingly interesting, from the fact that, coux)led with the discovery that all silver-tin alloys containing less than sixty per cent, of silver contract or shrink during the process of setting and for some time thereafter, it explains the condition which after a few months or years almost universally exists, — defective margins and imxDcrfect adaptation to the walls of the cavity of fillings made from these alloys. Annealing.— Dr. Black also made another important discovery while experimenting with alloys made by himself as to the influence of time upon cut alloys, or aging of the alloy, as it has been termed. Flagg, in his work on "Plastics and Plastic Fillings," claims that freshly cut alloys do not mix as well, neither do they give as good "setting," ^ ' shrinkage, " " edge-strength, " or " color' ' tests, as when properly ' ' aged. ' ' Black in his experiments found the opposite of this to be true in rela- tion to the shrinkage test. Freshly cut alloys which when made into amalgams did not shrink, or might expand, were invariably found to shrink after aging. The explanation of this j^henomenon at first seemed to be due to a slight oxidation of the particles of the cut alloy, by which its chemical relations to mercury were profoundly changed. Further ex- perimentation, covering several months of time, finally demonstrated the fact that neither oxidation nor time had anything whatever to do with the working qualities or the shrinkage of dental alloys. During these experi- ments the influence of temperature in aging of alloys was accidentally brought to his notice. He immediately set to work to verify or prove the error of the influence of this new factor, and finally discovered, after ex- haustive experiments, that the change was due to a molecular alteration in the particles of the cut alloy, induced by heat, or, in other words, it was due to a process of annealing or tempering. Various degrees of tempera- 310 OPERATIVE DENTISTRY. ture were used, ranging from 110° to 212° F. ; but the lower tempera- ture produced the best results. 130° F. was found to be the temperature which produced the greatest amount of shrinkage. Each alloy was found to have a definite ^^ shrinkage expansion range.^'' In some this range is all shrinkage, in others all expansion, and in still others it is both expansion and shrinkage. It was also found that by annealing or tempering any of the shrinking or expanding alloys these physical properties could be reduced to any amount, provided the tem- perature was maintained for a certain period. Each alloy has its zero point of contraction or expansion, beyond which no amount of annealing has any effect. ''The modified silver- tin alloys that have seventy-five per cent, of silver or more expand only. They cannot be made to shrink by aging, though their exxjansion can be greatly reduced. The same class of alloys containing as much as sixty-five per cent, of silver and less than seventy- five per cent, expand when freshly cut, and shrink when fully aged or tempered. Those containing from fifty to sixty-one or sixty-two per cent, of silver shrink only, but shrink much more when aged than when freshly cut. Those that contain less than fifty per cent, of silver first shrink and then expand. When fresh cut the expansion is the greater, when aged the shrinkage is the greater. "Alloys which contain sixty-five to seventy-five per cent, of silver are hard, and make hard and quick-setting amalgams ; they are also the strongest amalgams that can be made of silver and tin. Alloys containing less than sixty- five i)er cent, of silver are soft, and make soft, slow-setting amalgams. Alloys containing more than seventy-five per cent, of silver are soft, and make frail, slow-setting amalgams ; the slow-setting property occurs somewhat suddenly after passing the seventy-five per cent. ' ' Alloys which suffer no alteration in volume when unannealed shrink when annealed." The tables given on page 311 show the extent of the change produced in the alloys by the process of annealing in the unmodified and the modified silver- tin alloys, and the influence of the modifying metals also upon the shrinkage, expansion, flow, and crushing strength. They also demonstrate the fact that less mercury is required to amalgamate a given sample of alloy when annealed than when unannealed, and that both the flow and crush- ing stress of amalgams made from annealed alloys are slightly increased. Stability. — ^The physical property of amalgams designated as stability or rigidity \B the antithesis of "flow." That amalgam is the best, other things being equal, which flows the least, — in other words, is most stable, shrinks the least, and has the highest crushing strength. Such amalgams have been said to possess great "edge-strength." The term "edge-strength" was invented to designate the degree of re- sistance an edge or an angle of hardened amalgam offers to a force which on being applied might cause it to be fractured. It is evident, however, from the discovery of the property of flow under stress possessed by the "unmodified" and the " modified" silver- tin amal- gams, that it will be necessary to modify all former notions in relation to PLASTIC FILLING-MATERIALS. Exhibit of Unmodified Silver-Tin Alloys. 311 How prepared. Per cent. of Mereurj'. Shrinkage. Expansion. Flow. Crushing Silver. Tin. Stress. 40 60 Fresh-cut. 45.78 6 7 40.15 178 40 60 Annealed. 34.14 9 3 44.60 186 45 55 Fresh-cut. 49.52 4 8 25.46 188 45 55 Annealed. 32.13 11 1 28.57 222 50 50 Fresh-cut. 51.18 2 2 22.16 232 50 50 Annealed. 37.58 17 1 21.03 245 55 45 Fresh -cut. 51.62 2 2 19.66 245 55 45 Annealed. 40.11 18 17.53 276 60 40 Fresh-cut. 52.00 1 9.06 239 60 40 Annealed. 39.80 17 14.10 297 65 35 Fresh-cut. 52.00 1 3.67 290 65 35 Annealed. 33.00 10 5.00 335 70 30 Fresh -cut. 55.00 14 3.45 316 70 30 Annealed. 40.00 7 4.67 375 72.5 27.5 Fresh-cut. 55.00 42 3.92 275 72.5 27.5 Annealed. 45.00 3 3.76 362 75 25 Fresh-cut. 55.00 60 5.64 258 75 25 Annealed. 50.00 6 5.40 300 Exhibit of Modified Silver-Tin Alloys. Formulse. Modifying Metal. Gold 5 Gold 5 Platinum 5. . Platinum 5. . Copper 5. . . . Copper 5 . . . . Zinc 5 Zinc 5 Bismuth 5. . . Bismuth 5. . Cadmium 5. . Cadmium 5. , Lead 5 Lead 5 Aluminum 5 Aluminum 1 Aluminum 1 Silver. 35 35 33.25 33.25 33.25 33.25 33.25 33.25 33.25 33.25 33.25 33.25 33.25 33.25 33.25 33.25 33.25 33.25 33.25 34.5 34.5 How prepared. Fresh-cut. Annealed. Fresh-cut. Annealed. Fresh-cut. Annealed. Fresh-cut. Annealed. Fresh-cut. Annealed. Fresh-cut. Annealed. Fresh-cut. Annealed. Fresh-cut. Annealed. Fresh-cut. Annealed. Fresh-cut. Fresh-cut. Annealed. tl-t 1^ bo a 'u _o ft 52.33 1 3.67 33.00 10 5.00 51.52 4 3.35 33.53 7 5.06 47.56 1 4.62 30.35 7 6.07 51.87 9 9.68 37.33 7 8.20 53.65 23 2.38 35.60 5 3.50 56.65 68 1.83 40.65 9 2.07 46.26 4.78 23.67 6 5.58 57.57 100 6.40 47.25 5 3.54 44.17 1 4.88 32.76 10 7.18 65.00 445 46.98 166 12.60 38.26 48 17.90 290 335 329 380 330 395 273 352 343 416 290 345 288 308 225 290 290 276 198 213 their rigidity, for certain of them possess great resistance to fracture of the edges or angles, and still under the stress of mastication evince a decided tendency to flow, and consequently to a disturbance of the margins. All are therefore more or less unstable, and still some of them might be said to possess great '' edge-strength" when iu reality they possess very little. It therefore becomes necessary to discard or to modify the generally ac- 312 OPERATIVE DENTISTRY. cepted meaning of the term " edge-strengtli" to make it harmonize with the new data regarding the flow of all silver-tin amalgams under stress. Those amalgams which flow least have also the highest crushing strength, as will be seen by a reference to the above tables. The most stable '' un- modified silver-tin" amalgam contains 72.5 per cent, of silver and 27.5 per cent, of tin ; its shrinkage when annealed was 3 ; expansion, ; flow, 3.76 ; crushing stress, 362 pounds. The most staUe modified silver-tin amalgams are those which contain gold and those which contain copper. The formula of the former is, silver, 61.75 ; tin, 33.25 ; gold, 5. Fresh- cut, shrinkage, ; expansion, 1 ; flow, 4.62 ; crushing stress, 330. An- nealed, shrinkage, 7 ; expansion, ; flow, 3.07 ; crushing stress, 395. The formula of the latter is, silver, 61.75 5 tin, 33.25; copper, 5. Fresh-cut, shrinkage, ; expansion, 23 ; flow, 2.38 ; crushing stress, 343. Annealed, shrinkage, 5; expansion, 0; flow, 3.50; crushing stress, 416. Color. — The tendency of amalgam to discolor upon its surface through the action of oxygen and sulphur has restricted the use of this material to those portions of the mouth where the objectionable color would not attract attention. Ever since the early efforts of Townsend to manufacture a dental alloy that would not discolor, it has been the ambition of manu- facturers and individual experimenters to discover a formula which would produce an amalgam that would maintain its color under all conditions that are likely to be met in the mouth. The formula, silver 61. 75, tin 33.25, gold 5, comes nearest to making an amalgam that will not discolor. Flagg's formula, silver 58, tin 37, gold 5, also gives excellent results. The writer has for years made an alloy containing silver 65, tin 30, gold 5, which has stood the clinical test of twenty years without discoloration, and shows as good margins as many gold fillings which have done service in the same locations for a like period of time. The discoloration of amalgam is not confined alone to the exposed sur- faces of the filling, but often extends to the surfaces which lie against the dentin, causing discoloration of that tissue. This discoloration of the den- tin occurs most frequently under fillings which shrink or have been im- properly introduced, or in which secondary caries is progressing, causing leakage. This discoloration may be shallow or deep according to the character of the composition of the alloy, and is due to the formation of metallic sul- phides, from the decomposition of albuminous substances and the genera- tion of hydrogen sulphide. Black discolorations are found in amalgams containing silver and copper ; yellowish stains in those containing cadmium. To prevent discoloration of the dentin many operators are in the habit of lining the cavity with zinc oxyphosphate cement, or other barrier, before introducing the amalgam. Conductivity. — Amalgam as a conductor of heat and cold stands mid- way between gold and the basic zinc cements in the scale of the filling- materials. As a conductor of electric currents it stands next below gold. On account of the fact that amalgam is often used to fill cavities which are very large and dangerously near to the pulp, this organ should be pro- PLASTIC FILLING-MATERIALS. 313 tected from the dangers of thermal shock by the interposition of some low- conducting filling-material, like zinc oxyphosphate cement or gutta-percha. Galvanic shock is sometimes experienced when some other metal having a higher or lower potential than the amalgam filling comes in contact with it, as, for instance, a gold filling in an opposite tooth when contact is made and broken during mastication, or when a table fork touches it. As soon as the external surface of the filling becomes discolored gal- vanic shock ceases. This is due to the iuteri^osition of the metallic sul- phides, which are non-conductors of electric currents. Chemical Relations. — It has never been positively demonstrated that amalgam exercises any si^ecific therapeutic influence ui)on the dentin, although clinical evidence is abundant that such is the fact with those that contain copper. Miller, in experimenting with the various plastic filling- materials, as to their antiseptic properties and their retarding influence upon the growth of mouth bacteria, found that copper amalgam was the only one which possesses such qualities, and that it invariably manifested a retarding or preventive action upon the growth of bacteria. Fig. 448 shows this action upon a gelatin plate. Fig. 448. An inoculated gelatin plate containing : a, pieces of oxyphospliate cement one day old ; 6, pieces of gold amalgam one day old ; c, pieces of an old copper amalgam filling, age unknown ; d, pieces of stained dentin from a tooth wliich had been filled many years previously with copper amal- gam. (Miller.) Weagant, in writing uj^ou this subject, says, "Instead of having any injurious effect upon the teeth or surrounding tissues, it is decidedly bene- ficial to them, acting as an antiseptic or germ destroyer.'''' Fletcher also maintains the same view. According to Tomes, the sulphide of copper formed by the action of the hydrogen sulphide of the mouth upon the coj)per of the amalgam is readily converted, on exposure to air and moisture, into copper sulphate ; hence it is almost certain that the latter is formed upon the exposed sur- face of the filling. Cupric sulphate is freely soluble, and therefore is likely to xiermeate the dentin by following the tubuli. Sulphides of the other metals are not so readily converted into soluble salts, and therefore do not penetrate the dentin so freely. 314 OPERATIVE DENTISTRY. Flagg believes there is a gradual formation of soluble salts of silver, tin, and copper,— these metals forming the usual constituents of dental alloys,— which being dissolved are taken up by the contiguous dentin, thus changing the relations existing between the filling and the dentin, and ren- dering them more in harmony with each other ('' compatible"), and, '^ivith its incorporated metallic salts, becomes so in affinity with the amalgam filling as to insure almost completely harmonious apposition of tooth bone and filling, cessation, practically, of decay, and recalcification (?) with metallic lustre of decalcified dentin." Cadmium amalgam and amalgams which contain cadmium gradually softeu and disintegrate, and if the cadmium is present in large quantity, the dentin becomes decalcified and stained a bright orange-yellow from the formation of cadmium sulphide. Dental amalgams, as a class, are, however, chemically, practically in- soluble in the secretions of the mouth. Lactic acid and the other less common solvent agents found in the mouth have little or no effect upon them. COMPOSITION OF ALLOYS. The metals which are used in the manufacture of dental alloys are antimony, aluminum, bismuth, cadmium, copper, gold, platinum, palla- dium, and zinc. The following condensed table gives the composition of a few of the best-known dental alloys. H 0) > CO '6 a a p. o o 6 a a o < 51.52 51.90 57.5 50.35 37 85 35 49.27 40.60 40 40 50 48.48 46 42.5 43.35 58 60 60 48.24 52 40 50 50 1.70 .40 3.35 5 1.30 1.65 5 5 0.05 4.40 20 3 2.44 3 10 Chase's plastic tin 7 Antimony. (Stibium. Symbol, Sb. Fuses at 840° F.) — This metal has but little place in the manufacture of dental alloys. It is still used, how- ever, in a few of the alloys offered for sale, sometimes in large quantities. Amalgams containing antimony in considerable quantity are notably fine grained, very plastic, and do not shrink, but are exceedingly dirty to work. Small quantities of antimony added to silver-tin alloys, — tin in excess, — it is claimed, control the shrinkage. Aluminum. {Aluminum. Symbol, Al. Fusing-point, 1292° F.) — This is the lightest of the known metals, its specific gravity being 2.50 to 2.67. When alloyed with silver and copper it gives a non-tarnishing and uon- PLASTIC FILLING-MATERIALS. 315 corrosive quality to these metals and greatly increases their tensile strength . (Mitchell. ) Aluminum has been used as a constituent of dental alloys for the pur- pose of controlling the color and imparting greater tensile strength, but it destroys the integrity of the amalgam. Black found that the addition of five per cent, of aluminum to sixty-five of silver, and thirty-five of tin formed an alloy that when mixed with mercury ^'amalgamated nicely, forming a very white, soft mass, but it soon became too hot to handle." The thermometer indicated 186° F. The setting was also attended with the formation of considerable heat and enormous expansion, and later disintegration of the mass took place, resulting in the formation of a dark powder which would cohere a little on being pressed together. Disintegration did not take place when the mass was rapidly worked and packed in glass tubes, but the tubes soon became too hot to handle. A remarkable phenomenon is observed during the combining of the alloy with the mercury, — viz., the evolution of gas, which gave otf a distinct crepitating sound from the bursting gas-bubbles. The instruments used in packing the amalgam were darkened and corroded. The expansion of the material seems to be almost continuous, for Black states "that in twenty-four hours an expansion of one hundred and twenty points had occurred, as indicated by the micrometer ; at the end of the second day the expansion reached one hundred and eighty-one points ; and at the end of the third day two hundred and seventeen points, and though diminishing it did not stop. At the end of forty-three days it had reached the enormous figure of four hundred and forty-five points of expansion, when it passed beyond the capacity of the micrometer to register. "Annealing the alloys at 130° F. controlled the expansion somewhat, — it was stationary from the second day to about the fifth day, when it again began, slowly, and continued for about forty days." Aluminum, therefore, should have no place as a constituent of dental alloys, as its use not only destroys the value of the metals with which it is combined, but the added danger is to be considered of fracturing or burst- ing the thin walls of the cavity by the enormous expansion which takes place during the process of setting and afterwards. Bismuth. (Bisnmthum. Symbol, Bi. Fusing-point, 507° F.) — This metal has been used in dental alloys to control the shrinkage in the low- grade silver-tin alloys, in which the tin is largely in excess of the silver, as it expands very considerably on cooling. Alloys containing bismuth amalgamate with great readiness and with less mercury. Amalgams made from alloys containing bismuth are very dark. Dr. Black found the expansion-shrinkage range reduced in those amal- gams which contained it, but the flow was increased. Cadmium. {Cadmium. Symbol, Cd. Fusing-point, 442° F.)— The use of alloys containing cadmium was first suggested nearly fifty years ago by the late Dr. Evans, of Paris. It was claimed for this metal that it amal- gamated readily, that it did not discolor, and that it set very raj)idly, and made a durable filling. The hoj^es raised by these claims were soon dissi- pated, however, for gradual softening and disintegration of the mass took 316 OPERATIVE DENTISTRY. place, tlie dentin was decalcified and stained a bright orange-yellow -, but worst of all, the pulps of many of the teeth, filled with this material were (knitalized from the poisonous— irritating— effect of the cadmium sulphide, and which is stained yellow by the action of sulphuretted hydrogen. Cadmium is still used as an occasional component of dental alloys, being introduced in the proportion of from one to three per cent. It is claimed by those using it that it causes more ready amalgamation, controls discoloration, and increases the rapidity of the process of setting. Even this small quantity, nevertheless, would seem to be out of place, for all of the above advantages can be obtained by more satisfactory and less objectionable means. Dr. Black found ^'by the addition of five per cent, of cadmium to 61.75 per cent, of silver and 33.25 of tin that it greatly increased the expansion of the amalgam ; that it requires a large amount of mercury to amalgamate it ; that it sets very quickly, and makes very white and beautiful-looking fillings. ' ^ The expansion of the unannealed alloy was one hundred points in five days. Annealing largely controlled the expansion, reducing it to five points. In the expansion, the mass, if the walls of the cavity are smooth, slips squarely up and remains flat upon the top. "The flow in the unannealed alloy was 6.40; in the annealed, 3.54. The crushing strength was increased by annealing from two hundred and twenty-five to two hundred and ninety pounds." Copper. (Cuprum. Symbol, Cu. Fusing- j)oint, 1996° F.) — This metal in small quantities enters into the composition of all of the better class of dental alloys. An addition of five per cent, to the silver-tin alloys — tin in excess — increases the rapidity with which it sets, controls the shrinkage, gives a white color to the amalgam, increases its hardness, and exerts — by reason of the formation of sulphide of copper, which on becoming oxidized forms the sulphate — an antiseptic action upon the dentin. Dr. Black found that five per cent, of copper added to the 61.75 of silver and 33.35 of tin alloy caused the unannealed alloy to set very quickly. When annealed it set as slowly as the unmodified alloy. The expansion and the expansion- shrinkage range was greatly in- creased, the flow was diminished, and the crushing stress was raised to the highest in the series. Copper Amalgam. — This substance is a combination of pure copper and mercury in varying quantities, and is therefore a binary amalgam. It is made by several processes : (1) By adding freshly precipitated and washed metallic copper to an excess of mercury ; as soon as solution of the cop]3er is complete, the sur- plus mercury should be expressed by wringing the mass in a piece of chamois-skin. The plastic material remaining should then be formed into small tablets by pressing in suitable moulds ; when hardened it is ready for future use. Eollins, Ames, and others have published methods for making it by electrolysis. PLASTIC FILLING-MATERIALS. 317 (2) Eollins's metliod is as follows : Distilled water, five gallons ; sulphate of copper, enough to saturate ; sulphuric acid, one pound. Mix, filter, and pour into a wooden firkin with wooden hooi)s. All of the chemicals should be absolutely pure. Place ten pounds of pure mercury in a glass jar and immerse in the copper solution. To the zinc plate of a galvanic battery attach a gutta-percha- covered wire, having one end bare for about an inch. This exposed end is to be immersed below the level of the surface of the mercury. Tie granulated pure copper in a bag and hang it in the copper solution, con- necting with a wire to the carbon of the battery. The battery is to be kexDt in action till the mercury has absorbed enough copper to make a thick paste. Then remove and wash thoroughly in hot water till all of the sulphate solution has been removed. Squeeze out the softer amalgam and allow the remainder to harden ; heat it and renew the squeezing as before. This method insures an amalgam of perfect purity, and is simpler than any of the old and faulty methods in use. (3) Chandler suggested another method of making copper amalgam, which is as follows : To a hot solution of sulphate of copper add a little hydrochloric acid and a few sticks of zinc, and boil for about a minute. The copper will be precipitated in a spongy mass. Take out the zinc, pour off the liquid, and wash the copper thoroughly with hot water. Pour on the mass a little dilute nitrate of mercury, which will instantly cover every particle of copper with a coating of the mercury. Add mercury two or three times the weight of the copper, triturate slightly in a mortar, and finish by heating the mixture a few minutes in a crucible. Copper amalgam is prepared for introduction into the cavity of a tooth by heating one of the prepared and hardened tablets, crushing and grinding it in a -mortar, when it again becomes plastic. It may be made to set quickly or slowly as desired by squeezing out a portion of the mercury or by adding to it. On setting it becomes very hard, — in fact, it is the hardest of all the dental amalgams. It neither shrinks nor expands, retains good margins, and when properly made does not waste in the mouth. Its most objectionable feature is the black discoloration of its surface ; but this does not ajjpear so objectionable if the surfaces of the fillings have been nicely polished, for then the surface has a black polish instead of the rough, dirty black color that prevails if the surfaces are left in a rough state. This material has no equal for filling the posterior teeth of children under twelve years of age, where antiseptic qualities are needed. Its greatest value, however, lies in its use in the deciduous molars of little children for whom rapid operations are a necessity. Copper amalgam was the only alloy tested by Dr. Black which did not flow under stress. It suffers no change of form under stress, except to crush into fragments. It is as rigid and unyielding within the limits of its strength as a piece of hardened steel, and can neither be bent nor com- pressed. I^o shrinkage during setting could be discovered. A very slight expansion was always present, but it was so slight as to be of no impor- 318 OPERATIVE DENTISTRY. tance. In the large majority of the fillings which he tested it did not ex- ceed TuouTT of an inch. When it is once adapted to the walls of the cavity and hardened the adaptation is permanent, for it can suffer no change of form from the stress of mastication. These physical properties of copper amalgam give it permanence, and according to the opinion of Dr. Black, explain the power of the material to arrest caries rather than any chemical or disinfectant property of the copper or of its salts. Copper amalgam fillings, when well placed in properly prepared cavi- ties, retain their perfect margins, and do not discolor the tooth -structure ; and but for the wasting which sometimes occurs at the exposed surface and its dark color, this material would be the most satisfactory of all of the amalgams. Gold. (Aurum. Symbol, Au. Fusing-point, 2016° F.) — This metal during late years has become, in small quantities, a quite common com- ponent of most of the high grade dental alloys. It enters into these alloys in the proportion of from three to five per cent. Experiment has demon- strated that more than any other metal used, in proportion to the small amount required, except copper, it diminishes shrinkage, increases the rapidity of setting, controls the color, adds to its crushing strength, and imparts fine grain while in the plastic state. The addition of from five to seven per cent of gold to the silver- tin alloys — silver in excess — gives the best results. According to Dr. Black, the addition of five per cent, of gold seems to give a little softer working property to the amalgam and slows the setting. Annealing increases the soft working property. It requires a little less mercury than the unmodified alloy, and the flow was slightly increased. This amalgam is very tough and bears a heavy crushing stress before break- ing, and it controls the shrinkage-expansion range, three points. • Palladium. (Palladium. Symbol, Pd. Fusing-point, a little below that of platinum, about 3500° F., but requires the oxyhydrogen blow-pipe to fuse it.) — ^Palladium in combination with mercury forms a compound or binary amalgam, which has been recommended for use in the posterior teeth of children. It is made by combining palladium with three times its weight of mercury. Palladium is precipitated from a solution of its chloride by iron or zinc washed in nitric acid and dried. To this precipitate the mercury is added. Care is necessary in the mixing, as palladium forms a true chemical compound with mercury, and the action is so intense and the evolution of the heat so great that under certain circumstances an ex- plosion might take place. Palladium amalgam turns black upon the ex- ternal surface, but it does not discolor the dentin. It sets so rapidly that unless it is mixed very soft it becomes hard before it can be introduced into iihe cavity, consequently it should be worked rapidly and with warm instruments. Chandler found that the adding of a large proportion of gold rendered the palladium amalgam more tractable. It has no good qualities which are not possessed m a higher degree by copper amalgam. The only thing in its favor is its name, as it is one of the precious metals. PLASTIC FILLING-MATERIALS. 319 Platinum. (Platirmm. Symbol, Pt. Fusing-point, above 3500° F., and requires the oxyhydrogen blowpipe.)— According to Essig, platinum is only of value in an amalgam when combined with tin, silver, and gold in a proper proportion of mercury. Fletcher claims that the addition of a small quantity of platinum to a three-metal alloy, forty silver, sixty tin, ten gold, causes it to set quicklj^ Flagg looks upon platinum as having no value in a dental alloy over the same equivalent of tin, and therefore valueless as a component of amal- gams for filling teeth. Black found by adding five per cent, of platinum to the silver-tin alloy it made a dirty working amalgam, which blackened the hands, set slowly, flowed badly, and increased the shrinkage-expansion range. Silver. {Argentum. Symbol, Ag. Fusing-point, 1873° F.)— This is the most valuable and important of all the metals which enter into the compo- sition of dental alloys. In the superior grades of alloys it forms the largest portion, while in the inferior grades tin holds the first place. Silver is essential to the proper setting of an amalgam. Alloys in which silver predominates set much more rapidly than those in which tin forms the largest proportion. Alloys containing a large proportion of silver expand, while those com- posed largely of tin shrink. When silver and tin are united in the proper proportions they will make an amalgam having the lowest shrinkage- expansion range possible with any other known metals, except copper amalgams. This formula has been demonstrated by Dr. Black to be, sil- ver, 65 ; tin, 35 ; which gave shrinkage, ; expansion, 1. Tin. {Stannum. Symbol, Sn. Fusing-point, 442° F.)— This metal oc- cupies the next most important place to silver as a component of dental alloys. It shrinks in cooling more than any of the other metals which enter into these compounds. Amalgams which contain an excess of tin shrink badly, set slowly, and lack hardness. These objectionable features are overcome by combining it with silver or with silver and copper or silver and gold. The advantages of tin in a dental alloy are that it facilitates amalgamation, aids in producing a good color, and reduces conductivity. Zinc. (Zincum. Symbol, Zn. Fusing-point, 773° F.)— This metal in combination with copper formed one of the most ancient alloys of which there is any record. When added to dental alloys in which tin predomi- nates in large quantity, in the amount of one to one and one-half per cent, it completely controls the shrinkage, adds a satisfactory whiteness to the filling, and prevents discoloration. (Flagg.) Black found the addition of five per cent, to the 61.75 silver, 33.25 tin, formula greatly hastened the setting, and that it required more mercury for amalgamation ; but that the flow was decidedly decreased, the expan- sion range increased, and the crushing strength above the average. MAKING DENTAL ALLOYS. The rational method of making dental alloys is to melt that metal first which fuses at the lowest degree of heat. Tin, which forms a considerable part of all dental alloys, fuses at 442° F. This is the lowest fusing metal 320 OPERATIVE DENTISTRY. that enters into their composition, and should therefore be melted first, and tlie other higher fusing metals added in the order of their fasing-point, as, for instance, in a binary alloy the silver, which melts at 1875° F., should be added to the melted tin ; in a ternary alloy the copper, which fuses at 1996° F., should be added after the silver 5 and in a quarternary alloy the gold, which fuses at 2016° F., should be added after the copper, etc. The object of thus reversing the old method was to prevent the volatili- zation of the tin and thereby secure a definite compound, which was not the case when the tin was heated to more than 2000° F., as volatilization immediately takes place and an indefinite compound is the result. The practitioner who would make his own alloys should provide him- self with a good Hessian or sand crucible, holding ten or twelve ounces liquid measure, a pair of crucible tongs, and a quantity of borax to be used as a flux. Tin may be obtained at any hardware shop in the form of bars or ingots. Banca tin is the best, as being most free from impurities. Silve7^ can be obtained of any silversmith. Granulated silver is the best for the purpose, as it is divided into small beads or granules, and is therefore dissolved more rapidly in the melted tin than larger pieces would be. Copper can also be obtained at the hardware shop. Soft copper wire is the best form in which to buy it. This should be cut into very small pieces, about one-eighth of an inch in length. Gold in the form of foil scraps is always on hand in the office of every dentist. The other metals which sometimes enter into the composition of dental alloys are easily obtained, if it is desired to experiment with them ; but tin, silver, copper, and gold are the only metals that are used in a really first-class alloy. Flagg, in describing a "melt," says the crucible should contain a liberal amount of borax, which should be melted first, filling it about one-third full. " This is intended for a ' flux.' An ordinary coke or coal fire is all that is required for the ' melt ;' but it is, of course, more systematically and perhaps more readily done in the usual dental or smelting forge-fire. '' Having perfectly fused the borax, in it the tin is melted first, requiring but a low temperature, and after it is melted the granulated silver is added. These two metals are thoroughly stirred together with an iron rod or clay pipe-stem of suitable size and length, and when completely incorporated the copper — small pieces of wire — is added. This, like the silver, is soon melted, and may be equally homogeneously mixed. Lastly the gold is added, melted, and all is thoroughly stirred together with the iron rod or pipe-stem. ''When perfectly melted and mixed, the fused mass should be quickly poured into a broad, open, flat, shallow matrix made of iron or soapstone : this favors prompt cooling, and thus secures the greatest uniformity of distribution to the components." After the ingot has cooled it can be reduced to fine grains or coarse powder by filing, or the ingots may be cast in round bars or rods, and reduced to fine shavings by turning in a lathe. CHAPTEE XX. MANIPULATION AND INTRODUCTION OF PLASTIC FILLING-MATEEIALS. Amalgam is generally used under those conditions and circumstances in whicli a permanent filling is desired, but in which gold or tin and their combinations are inadmissible, either from the inaccessibility of the cavity, the frail condition of the tooth, the physical state of the patient, forbidding the nervous strain of long and tedious gold operations, or the inability of the individual to i)ay for such expensive service. Under no conditions, however, should amalgam be used in the anterior teeth. It may be used in some cases upon the distal surface of the first bicuspids, but never in a more anterior position. If the conditions require the use of plastics in the anterior teeth, the oxyphosphate cements and gutta- percha are the best for this purpose. Crutta-percha in the form of Hill's stopping is the most reliable of the plastics that are admissible in the anterior teeth. Amalgams, however, are not used to the same extent as they once were ; for many teeth that were formerly restored to normal contour by extensive oi)erations with amalgam can now, since the introduction of the more advanced methods of crowning, be better and more permanently treated by these methods. Various combinations of filling- materials have also been resorted to, in order to limit the uses of amalgam as far as possible to those positions in which they would be unobserved, to prevent discoloration of the tooth substance, or to give added beauty, strength, and durability to such fill- ings as were subjected to great stress ; as, for instance, in compound cavi- ties in the bicuspids and molars, when the cervical portion of a filling is made of amalgam and the morsal portion of gold. The preparation of cavities for the reception of amalgams requires the same care and thoroughness in all of its details as would be observed in preparing them for gold fillings, the only difference being that retain- ing grooves and pits are not necessary to aid- in the permanent anchorage of the filling, nor for starting it. If a general retentive form is given to the cavity, that is all that will be required to prevent its dislodgement under stress. Temporary separations are an essential preliminary step in the preparation of approximal cavities and in the restoration of contour in these locations. The Especial Uses of Amalgam. — 1. Amalgam is especially indi- cated in that class of cavities in which the cervical margin lies at some distance beneath the border of the gum, making it impossible from its inaccessibility and the difficulties in excluding moisture to successfully introduce gold. 2. In large distal cavities in the second and third molars, where, by 21 321 322 OPERATIVE DENTISTRY. reason of their location, their size and frail walls, or the physical condi- tion of the patient, gold fillings could not be satisfactorily placed. 3. In large buccal cavities in the molars, which extend to the gum line or beneatli. 4. In large approximal cavities in bicuspids and molars. 5. In large morsal cavities in the molars. 6. In compound cavities involving the mesial, distal, buccal, or lingual surfoces united with the morsal. The last four classes of cavities can, of course, be successfully filled with gold, and usually with better results, than with amalgam ; but conditions and circumstances are often presented in which the operator is obliged to choose amalgam to the exclusion of the better material. The exclusion of moisture is as essential in the preparation and steriliza- tion of cavities to receive amalgam as when gold is to be used, and the rubber dam should be adjusted for this purpose whenever and wherever it is possible to do so. Because amalgam is a cheaper material, and requires less skill to manipulate it than gold, is no reason why its introduction should be less carefully and conscientiously performed, or less pains taken with the finishing of such a filling, than would be expended upon it if it were gold. Better results, no doubt, would be obtained in the use of amal- gam if a higher degree of care in details were expended upon it. The employment of matrices is often a necessity in filling large compound cavities in the molars when it is desired to restore the contour of the in- FiG. 449. B Creager loop matrices. volved surfaces. In these cases the band matrix is the most serviceable, and to obtain the best results from its employment it should be permitted to remain until the amalgam has set sufficiently hard to allow it to be dressed to the desired form and polished. The ordinary loop matrix (Fig. 449) and the Guilford and Brophy matrices are not adapted to be left in the mouth by reason of their screw mechanism being in the way of the cheek. Dr. Herbst's method of forming a matrix to suit each individual case is admissible in this class of cases, for the reason that they are made in a moment, and can be so shaped that they will not injure the gum or the cheek, or interfere with the occlusion of the teeth ; consequently they may MANIPULATION AND INTRODUCTION OF PLASTIC FILLING-MATERIALS. 323 be permitted to remain upon the tooth for several days if desired. They are made as follows : A strip of German silver, No. 33 gauge, is cut of such width as will reach from the gum to the morsal surface of the tooth, and of sufficient length to embrace it and have about one-fourth of an inch to spare. This strip is then passed around the tooth, and the ends grasped with a pair of Herbst pliers — any flat nose pliers will answer the purpose, however — and drawn tightly around the tooth by pinching the ends to- gether. A close adaptation of the band to the tooth is thus secured. AVhile still holding the ends of the band with the pliers it is removed from the tooth, and the ends soldered together over an alcohol flame or a Bunsen burner with tinner's solder. The matrix is then replaced upon the tooth, and if it impinges upon the gum or interferes with the occlusion of the teeth, it is again removed and trimmed with small curved scissors to suit the requirements of the case, when it is again replaced after the rubber dam has been adjusted. If the band does not fit properly at the cervico-approximal border, it can be brought to position by the insertion of a wooden wedge. On the removal of the matrix, which should not be done until the amalgam has set, the filling can be shaped and polished as though it were gold. Mixing Amalgams. — The proper mixing of amalgams is an important factor in the ''shrinkage-expansion range" and in the "flow" of the mass, as shown by Dr. Black. Amalgams in which the alloy has been well incorporated with the mercury, or in which the mercury has been evenly distributed, shrink or expand less — heavily tinned amalgams shrink; heavily silver amalgams expand — than when they are insufficiently mixed or the mercury is unevenly distributed. The flow is likewise decreased by an even distribution of the mercury. Alloys made of metals which fuse at a comparatively low degree of heat, or alloys in which these metals predominate, require less mercury to dissolve the particles of the alloy and to form a plastic mass than do those made of metals which fuse at a considerably higher degree of heat. The silver-tin alloys — tin predominating — require less mercury to form a plastic workable mass than the same binary alloy in which the silver is in excess. Flagg and Fletcher both recommend the weighing of the alloy and the 7ner- cury for eyery "mix." Flagg's submarine alloy, which is composed of silver 60, tin 35, copper 5, requires from forty-six to forty-eight per cent, of mercury to make a workable mass. Flagg's contour alloy, containing silver 58, tin 37, gold 5, and other alloys of this grade require from forty-eight to fifty per cent, of mercury for perfect amalgamation, while those containing tin GO, silver 40, require only from thirty-seven to thirty-nine per cent., and those composed of tin 60, silver 35, gold 5, from forty- one to forty-three per cent, of mercury. If the operator knows the exact formula of the alloy which he is using, the proportion of mercury necessary to completely amalgamate the alloy is readily determined by the above. If, however, he does not possess the formula, he can ascertain by an experimental "mix" the amount of mer- cury necessary to obtain the best results in working any grade of amalgam. 324 OPERATIVE DENTISTRY. The amount of mercury required for the amalgamation of dental alloys is greatly increased as the amount of silver passes beyond sixty per cent., so that with an alloy containing seventy per cent, of silver it was very difficult to form a workable mass with fifty per cent, of mercury ; while with eighty per cent, of silver it becomes necessary to use as much as sixty per cent, of mercury. In mixing amalgams by weight, the amount of the alloy necessary for the case in hand should first be weighed, and then the exact proportion by weight of mercury added to it. These should be placed in a mortar and Fig. 450. Fig. 451. Flagg wafering pliers. mixed with the pestle until the mercury is thoroughly incorporated, making an even mass of firm consistency. It is then taken in the palm of the hand and kneaded into a mass, and compressed in a piece of chamois- skin or silk fabric, by wringing with the fingers or with a pair of flat-nosed pliers, or with Flagg' s wafering pliers, shown in Fig. 450. If the "mix" has been properly proportioned, no mercury can be ex- pressed by gentle pressure with the pliers, and but very little under severe pressure. The practice of adding more mercury than is needed in mix- ing an amalgam, and then expressing it in order to obtain a good working mass, is to be dej)recated, from the fact that the mercury is the solvent or fusing element in the amalgam, and whenever any portion of it is taken from the mass, by just that much the composition of the amalgam is altered and its physical characteristics changed. Dr. Black advocates the plan of mixing the amalgam in the hand until a fairly even distribution of the mercury is secured, as by this method his experiments showed that the strongest amalgam was secured. He found •also that '■^ any form of violence weakens the producV^ either in mixing, ex- pressing the excess of mercury by compression with a vice, or by undue manipulation in packing it into the cavity. Mixing amalgams in the hand is a dirty process, which discolors the hand and the fingers with the metallic oxides. To overcome this difficulty Glass mortar and pestle. MANIPULATION AND INTRODUCTION OF PLASTIC FILLING-MATERIALS. 325 Dr. Genese invented a rubber mortar to be held in the hand, the finger used in the mixing to be covered with a rubber finger-stall. Fletcher's method of mixing is to place the weighed proportions of alloy and mercury in a long glass tube and then violently shake it until amalgamation takes place. The writer prefers to mix amalgams by placing the desired amount of alloy in a mortar (Fig. 451) and adding the mercury little by little while the mass is being triturated, until a rather dry, crumbly mass is formed ; it is then turned into the palm of the hand and kneeded with the index-finger for a little time, when from the heat imparted to it from the hand it be- comes softer, and can be worked into a mass that will hold together. It is then placed in a napkin and compressed into a compact mass by wringing and squeezing between the thumb and finger, and afterwards cut into cubes of suitable size for the case in hand. This forms a mass which works easily and without the appearance of an excess of mercury upon the sur- face of the filling during the operation of packing it into the cavity. Washing Amalgams. — The idea of washing amalgams originated in the fact that alloys that had been cut for some time became oxidized upon the surface, and it was thought caused discoloration of the filling. It was believed that these oxides could be removed by washing in alcohol or other fluids and thus prevent discoloration. The real value of washing amalgams is, however, still a mooted ques- tion in the profession. Flagg believed that "washing" increased the tendency of the filling to shrink. Fletcher demonstrated that "washing" was absolutely detrimental, as it greatly facilitated and increased shrink- age. Burchard * recommends washing the amalgam in spirits of chloro- form, as it has been observed that washed amalgams retain their color better. The writer has never been able to discover any difference in the maintenance of color between washed and unwashed amalgams, and he has experimented very considerably in this line and has carefully observed the results in the mouth. The composition of the amalgam and the finish given to the filling are the main factors in controlling the tendency to discoloration. INTRODUCTION OF THE AMALGAM. The cavity having been prepared, the rubber dam adjusted, and the surface of the dentin dried and sterilized, the tooth is ready to receive the filling. The amalgam should be introduced into the cavity in small pieces. The first piece should be large enough to cover the bottom of the cavity when it is packed into place. The packing should always be done by hand-pressure. Another piece is then added to this and pressed into position with suitable instruments, and the filling built up layer after layer until the cavity is full. Various instruments have been devised for carrying the amalgam to the cavity besides the ordinary curved pliers. Fig. 452 represents an instrument for this purpose, which has one end armed with coarse serra- * American Text-Book of Operative Dentistry. 326 OPERATIVE DENTISTRY. tipns iuto which amalgam has been packed and permitted to harden. This produces a surface which will, by affinity or attraction, pick up small pieces of amalgam and hold them until they are deposited in the cavity. Other efficient instruments are shown in Fig. 453. These are of equal value in carrying the amalgam to cavities in the teeth of the upper and lower jaws. Fig. 452. Loadstone amalgam -carrier. For packing the amalgam into the cavity and shaping the filling there are no better instruments than those shown in Figs. 454, 455, and 456. Fig. 453. Amalgam-carriers. Packing and Condensing. — Several methods have been recommended for packing and condensing the amalgam,— viz., by burnishing, pressing, and tamping. Fig. 454. Dr. J. Foster Plagg's amalgam-instrumeuts. Burnishing the amalgam into place is the method most commonly fol- lowed, and it is claimed for this method that a better adaptation of the material to the cavity walls is obtained than by any other. Dr. Black has shown that "severe burnishing makes a weak filling." Pressure, steady and light, has, according to the same investigator, given the best results in his experiments upon the manipulation of amal- gams. Strong pressure, while bringing free mercury to the surface,— which MANIPUl^ATION AND INTRODUCTION OF PLASTIC FILLING-MATERIALS. 327 was removed, — gave the next best findings. Burnishing the filling into the cavity, if done moderatelj^, gave about the same results. Tamping or tapping the amalgam into position is a method which was introduced by Dr. Flagg, and is described as follows : "Tamping consists of delivering light blows, from the appropriate filling- instruments, upon the amalgam aftey^ it has been crushed into approximate position and apposi- tion. This 'tamping' is not to be done with the mallet, either hand, automatic, or electric, as a different kind of blow from any so given is far Fig. 455. Fig. 456. Kirk's universal Revised set of amalgam-instruments. approximal instru- ments for plastics. preferable. Tamping is a mingled push and Mow, which is soon acquired, and is as promptly recognized as very efficient in producing admirable results." The writer has followed this method for many years, and has never seen any good reason for changing to another. Wafering.— As the filling nears completion many operators are in the habit of finishing it with "wafers" of hard amalgam, after the manner suggested by Flagg. These wafers are made by compressing a portion of amalgam — either from the mix then being used or of a higher grade alloy — in chamois, with a pair of strong pliers, until all the mercury possible is ex]3ressed from it. The process of wafering hastens the setting of the amalgam and facilitates the final finishing. Lining. — In large cavities having thin walls it often becomes necessary to "line" the cavity, in order to give them the needed support and to prevent discoloration from the bluish appearance of the amalgam showing through the enamel, or from discoloration caused by the formation of sul- phides and oxides of the metals contained in the amalgam. The materials generally used for this purpose are the zinc oxy chloride and oxy phosphate cements. In lining cavities, the cement should never be allowed to rest in contact with the enamel margins. The margins should always be free from the cement, so that the amalgam may be in perfect contact with them through- out their whole extent. If for any reason the cement is allowed to remain in contact with the enamel margins, and the amalgam makes contact with that instead of the enamel, failure of the filling is bound to result by the washing away of the cement and opening the cavity to the agencies of caries. 328 operativp: dentistry. Two methods of lining are employed : one is to partially fill the cavity with the cement and allow it to become thoroughly hardened, and then to prepare it for the amalgam filling by removing the cement from the enamel margins, and give a retentive shape by undercuts in the base of the cement. Another method is to line the cavity with rather soft cement, care being taken to keep the enamel margins free, and while the cement is yet soft to introduce the amalgam, rubbing it into the surface of the cement. It is claimed for this method that by introducing the amalgam while the cement is in a plastic state it adheres to the enamel and renders retentive shaping unnecessary. Guarding. — In large cavities in the approximal surfaces of the bicus- pids and molars which extend beneath the gums, it becomes necessary to introduce a filling-material which by reason of its physical character and antiseptic action wall conserve the tooth-structure. Flagg describes "guarding" as "placing a material in apposition with the cervical wall of a cavity of decay, which shall, by its possession of certain physical characteristics, act under certain 'law,' to prevent, in greatest degree, the recurrence of decay at that 'vulnerable spot.' " Tin-foil is generally used for this purpose under gold fillings, while some operators use amalgam. In guarding the cervical margin under amalgam fillings, alloys are used which contain copper and a high per cent, of silver. For this purpose there is no alloy better than Flagg' s "submarine," composed of silver, 60 ; tin, 35 ; cox)per, 5. Copper amalgam may also be used for the same purpose, and some operators prefer it. Guarding with amalgams is usually employed in those cases in which caries has extended so far beneath the gum as to make it impossible to keep the cavity dry by adjusting the rubber dam. Under such circum- stances, after the cavity has been prepared an antiseptic should be applied, and sealed into the cavity with a temporary stopping. On the next day, after adjusting a napkin to prevent the entrance of moisture, the dressing is removed, and the submarine amalgam, which had been previously prepared, should be rapidly introduced, packed into position with suitable instru- ments or pellets of bibulous paper, and built up to the gingival border, the balance of the cavity being filled with a temporary stopping. The surface of the amalgam should be smoothed and overhanging edges removed while it is in the plastic state, for after it has "set" it is cut with great difficulty. At a subsequent sitting the surface of the amalgam filling beneath the gum should be nicely finished, when the rubber dam may be adjusted, the temporary stopping removed, and the balance of the cavity filled with ordinary amalgam. The amalgam which is used for the bulk of the filling should be one which will maintain a good color. An alloy containing silver 60. tin 35, gold 5, will best subserve the purpose. It sometimes becomes necessary to complete the operation at one sitting. Under these circumstances, the rubber dam can be adjusted after the cer- vical section of the cavity has been filled and the operation completed. This method is, however, not so satisfactory as the other, because of the MANIPULATION AND INTRODUCTION OF PLASTIC FILLING-MATERIALS. 329 danger of dis]3lacing the cervical section of the filling while the other is being packed into position, and the greater difficulty of perfectly finish- ing the cervical portion after the entire filling has been completed. Flagg recommends in all of those fillings which are located in surfaces of the teeth exposed to view, and where any discoloration would be objec- tionable, wafering such fillings with "facing" alloy, composed of, rela- tively, silver 57, tin 35, gold 5, zinc 3, as this gives a more accejitable color. COPPER AMALGAM. For the purj^ose of guarding and for submarine work in unexposed jDOsitions, and in the molar teeth of little children, some of whom will not tolerate the rubber dam or even a napkin, coi^per amalgam occupies a higli position as a filling-material and a couserver of tooth -structure. Cavities prepared for this material require but slight retentive shaping to retain it in position. Fig. 457. Ebony cone-socket handle, In preparing copper amalgam for introduction into a cavity, a cube of the material is placed in an iron spoon (Fig. 457), or grasped with a pair of pliers, and held above an alcohol or Bunsen flame until the mercury shows itself in tiny globules upon the surface, when it is placed in a mor- tar, crushed and ground into a soft mass. The cavity, when possible, should be protected from moisture by adjust- ing a rubber dam or a napkin and sterilized. The amalgam is then intro- duced in small pieces, and packed by tamping or burnishing the material against the walls of the cavity until it is full. The surface of the filling may be smoothed with a broad spatula or by wiping with pellets of cotton. Large cavities may be advantageously filled or lined with zinc oxy- phosphate cement for the lower two-thirds or three-fourths of the cavity and the filling finished with amalgam. This practice, however, is im- peratively demanded in large and deep-seated cavities which have ex- tended nearly to the pulp, to guard against shock from thermal changes. By the aid of "Mack's" screws, set in the jjulp-canals, the Herbst matrix, and a strong, quick-setting alloy — Flagg' s contour — large contour operations, like the building of a large section of, or the whole crown of, a molar, may be successfully accomplished, as shown in Figs. 458, 459, 460, and 461. It is important that the matrix fit the cervix of the tooth closely, and be so adjusted to the occlusion of the opposing teeth that the jaws can be closed in a normal manner. After the cavity has been filled or the 330 OPERATIVE DENTISTRY. crown restored, tlie matrix sliould be allowed to remain for a few hours, or better, overnigiit, wlien the surfaces may be trimmed and shaped by filing and grinding. In packing the amalgam great care, for obvious reasons, should be exercised to secure perfect adaptation of the material to the walls of the matrix and the surfaces of the screws. Fig. 458. Fig. 459. Fig. 460. Fig. 461. Cavity prepared. Cavity filled. Cavity prepared. Crown restored. If the matrix has been carefully fitted to the cervix and the occlusion properly adjusted, there will be very little trimming and carving required to give proper form to the restored crown. Finishing. — The proper finishing of an amalgam filling is as important as the finishing of gold fillings. An imperfectly finished filling will, by the roughness of its surface, its ragged or overhanging edges, invite a re- currence of dental caries at the enamel margins by the retention of ferment- able material and the protection offered to the zymogenic bacteria, while fillings that are highly finished retain a better color, or, in other words, do not tarnish or oxidize so readily. The process of finishing amalgam fillings which have become hard by crystallization is so similar to the finishing of gold fillings that it is not necessary to describe it, as it would be only a reiteration of these methods. GUTTA-PERCHA. Gutta-percha was first introduced to the consideration of dental practi- tioners a little over fifty years ago (1847) as an admirable material for temporary fillings in frail teeth, on account of the ease with which it could be manipulated, its non-irritating and non-conducting qualities, its in- solubility in the fluids of the mouth, and its fair resistance to the attrition of mastication. Its color, dark brown, was so objectionable that it found little favor with the profession on this account. But upon the introduc- tion soon afterwards of a secret preparation known as "Hill's stopping," which was white in color and possessed all of the advantages of the crude gum, it rapidly came into use for a temporary stopping. Its inventor, Dr. Hill, however, had very exalted views of its value, for he said, "Though I do not expect it to supersede gold entirely, yet I believe it can be advantageously substituted for that material in many instances." Although this opinion has never been generally concurred in by the profession, it was nevertheless the very best material for tempo- rary fillings that the dentist has ever had placed in his hands j and^ in fact, MANIPULATION AND INTRODUCTION OF PLASTIC FILLING-MATERIALS. 331 it has proved iu many instances, when introduced into cavities wliich. by their position were not subject to the attrition of mastication, to be worthy to be classed as a permanent filling- material, for it has been known in such locations to have perfectly j)reserved the teeth so filled for from five to ten years, and even longer. With the death of Dr. Hill the manufacture of the "stopping" ceased, and although several alleged analyses of the material have been published, no one has ever been able to produce a substance that possessed all of the qualities of Hill's stopping. A formula which makes a very good substitute for it, and which, when published, was claimed to be identical with Hill's formula, is as follows : R Quicklime, 2 parts ; Quartz, 1 part ; Feldspar, 1 part. These are ground to an impalpable powder and mixed. Pure gutta- percha is then heated to a plastic state and the powder kneaded into it as long as it will receive it without becoming brittle. The white gutta-percha preparations of to-day are made in imitation of Hill's stoj^ping, but they are only imitations to those of the older members of the ]3rofession who had any experience in the use of the original material. The gutta-percha jpreparations as manufactured at the present time are composed chiefly of gutta-percha and oxide of zinc, these materials being kneaded together — upon an iron or porcelain slab heated over boiling water — by the aid of a broad steel wedge-shaped instrument termed a kneader. The greatest care has to be exercised in its manufacture to prevent overheating (heat-rotting), as this spoils the material by destroy- ing its toughness and causing disintegration of the mass. Gutta-percha as prepared for the use of the dentist is in three forms, — one, the well-known pink base-plate gutta-percha ; another, the white gutta-percha prepared in small cakes, sticks, or pellets ; and the third, a softer "temporary stopping" used for covering dressings. The white gutta-XDercha is prepared in three grades, — viz., "low heat," "medium," and "high heat." The "low heat" grade becomes sufficiently plastic for manipulation at temperatures ranging from 140° to 200° F. The "medium" grade is rendered of equal plasticity by a temperature ranging from 200° to 210° F. The "high heat" grade requires a temperature of from 216° to 230° F. to render it sufficiently ijlastic for manipulation, and is therefore more liable to be overheated and its integrity destroyed than are those which can be rendered plastic over hot or boiling water. Flagg thinks for this reason the medium grade of gutta-percha is the best for general use. Flagg' s formulae for the "low heat" and "medium" grades of gutta- percha are, "low heat," gutta-percha, one part ; oxide of zinc, four parts ; "medium," gutta-percha, one part; oxide of zinc, six to seven parts by weight. Physical Characteristics.— Gutta-percha stopping is the most bland and non-irritating filling-material known, and by its non-conducting prop- erties of both heat and electricity it becomes the most valuable filling- material for the temporary treatment of hypersensitive dentin and- nearly 332 OPERATIVE DENTISTRY. exposed pulps that the dentist has at his command. It is not acted upon by tlie fhiids of the mouth, at least in any appreciable degree, while it is a notable fact that it maintains its integrity better in the fluids of the mouth than when exposed to the atmosphere. Softened gutta-percha pellets will unite with each other under pressure when the surfaces are dry, but they cannot be made to do so when wet. It contracts on cooling, so that it is almost impossible to make an absolutely moisture-tight plug ; in fact, very few fillings made out of the mouth will resist the "carmine test ;" and yet with this great fault its record as a "tooth-saver" is exceptionally good. It is susceptible of being colored to imitate any shade of the teeth. It is not so hard nor so rigid as the other filling-materials, but it has been no- ticed that its hardness increases with time when it has been properly intro- duced into a cavity that is protected from attrition. Gutta-percha fillings which soften and disintegrate in the mouth have been spoiled by "heat- rotting," either during the process of manufacture or in being prepared for introduction into the cavity. The pink base-plate gutta-percha assumes a polished surface, and seems to wear better when subjected to attrition than do the white varieties. Some operators prefer the pure gum to any other form, believing that its admixture with the substances that are used to harden and bleach it detract from its wearing qualities and only render it more destructible. Use of Gutta-Percha. — Gutta-percha is employed principally as a temporary filling in the deciduous and permanent teeth, for "sealing in" dressings, treating hypersensitive dentin, for the permanent filling of root-canals, for "guarding" oxyphosphate fillings, for capping or pro- tecting nearly exposed pulps, for permanent fillings in locations not ex- posed to attrition, and in badly broken-down teeth which are too frail to be filled with metallic stoppings. Dissolved in chloroform — chloro-percha — it is often used to line cavities which are to receive zinc oxychloride or zinc oxyphosphate cements, the object being to jirotect the pulp from irri- tation and pain which might be induced from the zinc chloride in the former and the glacial phosphoric acid in the latter. The form of gutta-percha known as "temj)orary stopping" is furnished in two colors, pink and white, and is used j^rincipally for "sealing in" dressings that have been placed in carious cavities to reduce hypersensi- tiveness or to destroy the vitality of the pulp^ or for covering dressings that have been placed in the root-canals of devitalized teeth. On account of its extreme softness, however, it is not intended to subserve more than the most temporary purpose, although this feature makes it very valu- able, as it is easily and quickly introduced, and as easily and quickly removed. Many operators confine their use of the pinTc variety to covering arseni- cal applications and other dressings which the conditions of the tooth make imperative should be changed at the next sitting, while the white is used for those cases which are not urgent, or are being tested as to their fitness to receive a permanent filling. Gutta-percha which is prepared for filling the root-canals of devitalized teeth is made in the form of long slender cones or points, either by rolling MANIPULATION AND INTRODUCTION OF PLASTIC FILLING-MATERIALS. 333 or cutting of proper size and form to be readily introduced into the canals. They may be prepared either from the pink base-plate gutta- percha or from the white variety. Gutta-percha by reason of its indestructibility, non- irritating character, ready adaptability, and ease of manipulation is the material pay^ excellence for filling root-canals. For " guarding^ ^ zinc oxyphosphate fillings at the cervical margin it is of great value, for it prevents the dissolution of the cement which is so com- mon at this location, and thereby relieves the anxiety of the oj^erator over the possibility of the oxyphosphate being undermined in a few months and the carious process re-established. In many individuals the oxyphos- IDhate cement wears well, even in positions exposed to the attrition of mas- tication, but is rapidly disintegrated at the cervical margins. By "guard- ing" with gutta-percha at these locations the durability and value of such fillings is greatly increased. As a capping for nearly exposed pulps gutta-percha of the "low heat" grade has no equal, its greatest value lying in its non-conducting quality, which protects the pulp from thermal shock. As a permanent filling in large cavities in the deciduous and permanent teeth not subjected to the friction of mastication, especially buccal cavi- ties in molars and simple labial or approximal cavities, the "high heat" grade may be depended upon to wear well and to protect from a recurrence of caries. It has its greatest usefulness in those cavities in which the carious process has penetrated to such depth as to nearly expose the pulp, — the pulp being first protected by a layer of the "low heat" grade,— and in devitalized teeth which have very frail cavity walls or are inclined to pericemental or apical irritation, and by reason of its non-irritating quality in all cavities which extend beneath the free margin of the gum. Many operators use it to the exclusion of all other filling- materials for stopping approximal cavities in the anterior permanent teeth of children under twelve to fourteen years of age. Fillings in these locations, if properly introduced, may be counted upon for doing good service for from five to eight years or longer. The pink base-plate gutta-percha wears better in all exposed surfaces than the white, but the white, by reason of its more harmonious color, should be invariably used in all cavities in the anterior part of the mouth. The i^ink base-jDlate is also a very serviceable material for maintaining a temporary separation of teeth which are to be filled with metallic stoi)pings, but in which the pericemental irritation induced by the sepai^ating pro- cess is so great as to make it necessary to j)ostpone the ox^eration to a later date. Or it may be used for gaining temporary separations between the bicuspids and molars prei^aratory to introducing contour fillings, by pack- ing the approximal cavities full of the material and allowing the force of mastication coming upon the fillings to gradually separate the teeth by the spreading of the material. Methods of Softening. — Upon the proper softening of the prepared gutta- percha stoppings depends their integrity and durability. The greatest of care should be exercised in softening gutta-percha that it be not overheated 5 this 334 OPERATIVE DENTISTRY. Fig. 462. caution cannot be emphasized too strongly, as tlie complaints so often made of gutta-perclia '^rotting" or disintegrating in the mouth are the result of overheating, or ^' heat-rotting," before introducing the filling, and not dis- integration of the material from the action of the oral secretions, as some have supxjosed. Permanent results cannot be obtained with gutta-percha — except by accident — when the material is heated by holding it in the flame of a lamp or Bunsen burner, as practised by so many operators, as by this method it is usually overheated, and as a result, when subjected to the influences of the oral secretions, softening and disintegration take place. Dr. Flagg some years ago invented the device shown in Fig. 462 for heating the various grades of gutta-percha and the packing instruments. It is composed of a lamp-stand, which carries a small metal wa- ter-tank, upon the cover of whicli are arranged two shelves ; tlie upper one, which receives the least amount of heat, is intended for softening the "low heat" grade of gutta-percha, the lower one softening the "medium" grade, while the cover of the tank is utilized for heating the "high heat" grade and the pack- ing instruments, the handles of which rest upon a notched rack and the ijoints upon the cover of the tank. Water is placed in the tank and heated to the boil- ing-point. Overheating of the various grades of the material becomes impossible by using this method of softening. Of late years there has been a demand upon the part of some 0]3erators for harder grades of gutta-percha, which require a degree of heat for their softening greater than can be obtained by boiling water. The thermoscopic heater of Dr. W. Storer How,* shown in Fig. 463, meets these require- ments in a most perfect and scientific manner. The heater is composed of a block of steatite, selected for its heat-retaining qualities and the desira- bility of its surface. At one end is a wooden handle, at the other end a circular recess, in the centre of which is a small disk. A, made of fusible metal which melts at 212° F. On the heater within the circular recess are placed a suitable number of gutta-percha i)ellets, as 1, 1, and the heater is held over the flame of a spirit-lamjp or Bunsen burner until the disk of fusible metal is melted, when the gutta-percha will be sulflciently softened for introduction into the cavity. The heater will maintain the proper temperature long enough for the completion of an ordinary Flagg's improved gutta-percha softener and tool-heater. * Dental Cosmos, vol. xxxiv. p. 281. MANIPULATION AND INTRODUCTION OF PLASTIC FILLING-MATERIALS. 335 operation, but if tlie metal in the mean time loses its fluidity and tlius indicates tlie lowering of the temperature, it can be restored hj hold- ing the heater for a moment over the flame until the metal again becomes fluid. Fig. 463. Dr. How's thermoscopic heater. When the metal disk is fused the pellets 1, 1, will be at a temperature of about 212° F., while pellets at 2 would have a temperature of about 200° F., and those at 3 and 4 about 194° and 180° F. respectively. Disk B, which is made of fusible metal which melts at 230° F., is provided as a substitute for disk A, which may be melted and poured out, and B used in its stead. In this manner the "high heat" gutta-percha and the lower grades may be properly softened without the least degree of "heat-rotting" of the material. Manipulation of Gutta-Percha. — Instruments which are suitable for filling difficult and inaccessible cavities with gold are best adapted for packing gutta-percha, for, as a rule, the cavities in which this material is generally used are in difficult and inaccessible locations. In packing this material it is best to use warm instruments, as it is important that the whole mass of the filling be kept in a plastic state until perfect adaptation to the walls has been secured. The jpreparation of cavities to receive gutta-percha fillings, while re- quiring the thorough removal of all decalcified and infected dentin, should also be directed to the conservation of the enamel walls to the full limit of safety against fracture, especially in preparing approximal cavities in the incisors and cuspids. With an intact labial enamel wall, though it be transparent, gutta- percha can be so packed against it as to protect and strengthen it, and at the same time so restored in color as to defy detection except by close scrutiny. It is important in the introduction of gutta-percha that moisture be ex- cluded from the cavity. The rubber dam should therefore be adjusted, and 336 OPEEATIVE DENTISTRY. as much care taken in this respect as would be given to it if the cavity were to 'be filled with gold. The cavity should next be dried and steril- ized, and again dried, after which the gutta-percha may be packed in place. This may be done by either one of two methods. The first method is by introducing the gutta-percha in small pellets into the cavity, — which has been previously warmed by a blast of heated air, — packing them first into the most inaccessible parts of the cavity, and finishing with a larger mass. The second method is to introduce a single large mass somewhat larger than the cavity, and with a broad spatula-like instrument, with a rocking motion work it into the cavity much as would be done in taking an im- pression of the part. Some operators prefer to line the cavity walls with oxychloride or oxyphosphate of zinc cement in those cases in which the walls are very thin and frail ; tinting these materials to match the color of the tooth, and after it has hardened to fill the balance of the cavity with gutta-percha after one of the above methods. Dr. How believes that the common method of introducing the filling in' small pellets is responsible for leaky fillings. He says, ^' There is good reason for the belief that the common mode of successively introducing small pieces of perfectly softened gutta-percha into a comparatively cold cavity, and employing instrument points more or less heated for packing the cooled plastic against one side of the cavity after another, must in the nature of the case result in a leaky filling, such as gutta-percha is com- monly said to make, whereas the defect is due not to the material, but to its inconsiderate manipulation." Dr. How claims that by the "single mass" method perfectly moisture-tight plugs can be made, as demonstrated by him, such fillings successfully resisting the aniline-dye test after several days' immersion. Finishing Gutta-Percha Fillings. — Gutta-percha fillings which have been properly introduced need but little trimming or finishing. To hasten the hardening of the filling, a spatula which has been immersed in ice- water and quickly dried should be applied to the surface of the filling to abstract the heat, and as soon as it has been sufficiently cooled the over- lapping edges may be removed with Dr. Gordon White's sickle-shaped trimmers (Fig. 444) or those of Dr. E. K. Wedelstaedt. The surplus ma- terial should be shaved off in thin slices, never in large mass, as this effort would be likely to drag the filling away from the margins. The trimming should always be from the centre of the filling towards the circumference, for the same reason. The surface may be finished by a rapidly revolving cuttle-fish disk, or by wiping the surface of the filling with a tape mois- tened in chloroform. ZINC CEMENTS. The zinc cements — or "osteoplastics" as they are sometimes called — used in dentistry are the oxychloride, the oxyphosphate, and the oxy- sulphate. The oldest of these is the oxychloride, which was first intro- duced to the profession about the year 1850, or a little later, by M. Sorrel MANIPULATION AND INTRODUCTION OF PLASTIC FILLING-MATERIALS. 337 as a permanent filling-material, and on account of its hardness, whiteness, and apparent insolubility, it gave promise at first of fulfilling the expecta- tions of its inventor, but later all hopes in this respect were abandoned, as it was found to undergo rapid disintegration whenever the material was placed in contact with the margin of the gum or very near to it, and it also contracted very considerably in hardening, and therefore resulted in leaky fillings. Zinc oxycliloride is formed by the combination of calcined and pulver- ized zinc oxide with a solution of zinc chloride in distilled water : ZnO + ZnCl, + H,0 = 2ZnClHO. '' Zinc oxide is made by heating metallic zinc in a current of air. To make a pure white zinc oxide for pharmaceutical purposes, pure precipi- tated zinc carbonate should be heated at low red-heat until the water and carbonic oxide are wholly exx^elled. This can be done below 500° F. Too high heat will give the product a yellow color and make it feel harsh. A small quantity should be used in heating. A good quality of zinc oxide should come in the form of a soft, flaky, impali^able powder of si3. gr. 5.6. It should turn yellow when heated in a test-tube, and become white again on cooling. It is insoluble in water, but completely soluble in dilute acids. It is not darkened by sulphuretted hydrogen. ^^Zinc chloride is made by heating zinc in a current of chlorine, or by the action of hydrochloric acid on granulated zinc, or zinc carbonate, and evaporating the solution to dryness. It occurs in the form of hard, dirty- white masses, very deliquescent, and forming a clear solution in water. It is one of the most soluble substances known. Zinc chloride has a caustic, sharp taste, and is acid in reaction. It is soluble in alcohol and in ether." (Mitchell.) Zinc oxychloride as prepared for dental use is composed of a powder and a liquid. The poicder is made by thoroughly triturating in a mortar two grains of borax and four x^ennyweights of zinc oxide. These are then placed in a small crucible and subjected to a glowing red-heat for from seven to ten minutes, forming what is termed a ^^frit," which when cooled is finely Xjulverized in a mortar. Sixteen pennyweights of zinc oxide are then placed in a crucible and subjected to a moderate red-heat for three or four minutes, and allowed to cool. After which it is gradually added to the '■ ' frit, ' ' and the whole thoroughly pulverized and mixed. It should then be transferred to a glass- stoppered bottle to x^rotect it from the moisture of the atmosphere. The liquid is made by dissolving half an ounce of zinc chloride in two or two and a half drachms of water, and after several shakings allowed to settle for a few days, when the clear fluid may be decanted off. If the solution does not clear it should be filtered. (Flagg.) Mixing. — For mixing zinc oxychloride, or in fact any of the zinc cements, a glass slab and a suitable spatula are necessary (Fig. 464). Upon the mixing-slab are placed one or two drox^s of the fluid, and near it a quantity of the powder. These are then incorporated and worked into a thick creamy paste, and it is ready for use. The filling is introduced into 22 338 OPERATIVE DENTISTRY. the cavity by small spatulas (Fig. 4G5), and adapted to the walls by means of pellets of bibulous paper, which remove any surplus of liquid, and thus hasten the setting. Characteristics and Properties. — Zinc oxychloride sets rather slowly and is not so hard when set as the oxyphosphate cements. About fifteen min- utes are required for it to set sufficiently hard to allow amalgam to be packed upon it without displacement, and half an hour to an hour for a Fig. 4G4. Fig. 465. Bevelled edge (glass) mixing-slab and spatula. gold filling. Some operators defer the operation of covering it with a metallic filling until a future sitting, protecting the cement with a gutta- percha filling until that time, in order that the cement may furnish a harder foundation for the metallic filling. When used in large masses it shrinks notably. It stands low in the scale as a conductor of caloric, and like all compounds which contain zinc oxide, it is readily decomposed by the action of acids and alkalies. Zinc oxychloride is not a definite chemical compound, and cannot be made by the method of mixing without one or the other^of the constituents being found in excess. According to C. S. Tomes, there is always free zinc chloride to be found in the finished filling, and conse- quently the filling is hygroscopic. When freshly mixed, if it is brought into contact with vital soft tissues it is irritating and escharotic. Conse- quently it should never in the creamy state of the mix be brought into contact with an exposed pulp, or one nearly exposed, as inflammation and devitalization in a large majority of instances would be the result. If the ma- terial is mixed to a doughy consistency, it may sometimes be used as a capi^ing for nearly exposed i^ulps. The danger to the i3ul]3 lies in the irritating effect of an excess of the zinc chloride. After the filling has set, it retains antiseiDtic properties for some time thereafter, as shown by Miller in his experiments upon the antiseptic properties of filling-materials. MANIPULATION AND INTRODUCTION OF PLASTIC FILLING-MATERIALS. 339 Zinc oxychloride has also an obtunding effect upon hypersensitive dentin if left in the cavity for a month or more. It is also, by reason of its antiseptic properties, an excellent material with which to fill the roots of devitalized teeth. It may be used alone for this purpose, or combined with other materials like gold-foil, gold wire, lead, or gutta-percha points ; while on account of its extreme whiteness it may be successfully used as a lining of cavities to restore the color of devitalized teeth. Zinc Oxyphosphate. — Cements of this class are formed by a combina- tion of calcined zinc oxide and orthophosphoric acid, 3ZnO + 2H3PO^= Zn3(POj2 + 3H^0, nominally, for on account of the impurities in the zinc oxide and of the inconstancy of the acid itself, their actual composition is one of considerable variability.' "Phosphoric acid has modifications — metaphosphoric and pyrophos- phoric acids — which differ from it in the number of the combined equiva- lents of water ; and these forms pass into one another somewhat readily. Thus a solution of metaphosphoric acid when boiled passes into orthophos- phoric acid ; pyrophosphoric acid may be prex)ared by evaporating a solu- tion of orthophosphoric acid at a temperature of about 215° F. ; but it, in the presence of water, slowly passes back into the orthophosphoric acid at ordinary temperatures. Each of these acids is capable of forming a number of different salts — monobasic, dibasic, tribasic, or tetrabasic salts — with the same metal, and thus a large number of zinc jphosphates are known." (C. S. Tomes.) Zinc oxypliosphate as known to the dentist is composed of a powder and a liquid. The powder is zinc oxide, the liquid one of the many forms of phosphoric acid. When glacial phosphoric acid is used, the cement is termed oxymeta- phosphate. Cements which are made from the commercial phosiDhoric acid are not so durable as are those which are made from the pure acid. Purity in the materials which enter into the composition of the zinc oxyphosphates is a sine qua non. Some manufacturers are in the habit of preparing the powder from the commercial metallic zinc, and as a result it often contains impurities, like the arsenic compounds, which, according to some writers, exijlains in a measure the reason why teeth which have been filled with oxyphosiahate cement, and vital teeth carrying crowns and suj)porting bridges which have been set with this material, have sometimes been devitalized. The writer, however, has never seen a case of devitalization of the pulp under zinc oxyphosphate which could not be satisfactorily ex^^lained upon some other hypothesis. Ames, in exi^erimenting on the zinc oxyphosphates {Dental Cosmos, 1890), x)repared specimens of zinc oxide containing seven per cent, of arsenous oxide (zinc arsenite), and with this compound apjDlied to cavities in vital teeth he was unable to produce devitalization of the pulj). The zinc oxide and arsenic compound used in these exj)erimeuts was prepared "by heating in a sealed tube certain proportions of zinc oxide and arsenous oxide. In confinement a full red heat will effect a thorough combination of the maximum amount of arsenic with the zinc, which 340 OPERATIVE DEKTISTRY. seems to be about seven per cent. This is sufficient to give an extensive mirror with the Marsh test. This combination is such that 3000° F. can afterwards be applied to the compound in an open crucible without affect- ing the composition. This is necessarily the same compound which is formed in infinitesimal quantities in the manufacture of cement powders." He believes that tlie arsenic found in the zinc cements is in combination with the zinc in the form of zinc arsenite, and that tliis combination is wholly devoid of poisonous properties per se ; and that the combination is not broken up to the extent of forming potent arsenous acid, except under rare and unjustified conditions. To obtain zinc oxide and glacial phosphoric acid in a pure state are expensive processes ; the temptation, therefore, of the manufacturers to send out materials which are less troublesome to make and of inferior grade is very great. The jpoivder is made by treating zinc oxide with nitric acid, evaporating it to dryness, calcining and pulverizing. (Flagg.) The calcining process requires several hours, the material being kept at the highest forge heat during this time, thus forming a vitreous mass, which on cooling is re- moved by breaking away the crucible. After thorough pulverization it is sifted through a fine bolting-cloth and placed in tightly stoppered bottles to protect it from the atmosphere, for if it is exposed it absorbs carbon diox- ide from the air, and a portion of the material is converted into hydrated zinc carbonate. The presence of carbon dioxide is noticed by the effer- vescence which takes place in such samples when phosphoric acid is added to them, the effervescence being due to the liberation of carbonic oxide. Coarse powders, according to Ames, produce cements with greater crush- ing stress than those made from fine powder. Eollins's process for making the j)owder is, "Dissolve pure zinc in chemically pure nitric acid to saturation, then evaporate to dryness, i^ack in a crucible, and heat until no more fumes are given off. When cool break up the crucible, and after separating the oxide of zinc, pulverize it to a fine powder." Flagg terms the zinc oxide made in this manner "nitrate of zinc," and claims it makes a far superior cement to those j)owders which are x^roduced by calcining zinc oxide. The liquid which is combined with the powder in making zinc oxy phos- phate cement (oxymetaphosphate) is glacial phosphoric acid, HPO3 (metaphosphoric acid). This form of the acid is derived by subtract- ing two molecules of water from orthophosphoric acid, H^PO^ — 2H2O = HPO3, metaphosphoric acid. Eollins's process of making metaphosphoric acid is, "Take a pure solution of orthophosphoric acid, which is easily obtainable, of a strength of sixty per cent. ; evaporate it in a platinum evaporating dish until white fumes are given off. Then heat it to a bright redness to be sure that it is all converted ; cool and make into a thick syrup." (Mitchell.) The impurities found in the commercial glacial phosphoric acid forbid its use in the making of zinc oxyphosphate cement. These impurities con- sist of variable quantities of sodium, calcium, and magnesium phosphates. MANIPULATION AND INTRODUCTION OF PLASTIC FILLING-MATERIALS. 341 "These salts are permanently soluble in tlie phosphoric acid, and therefore give no evidence of their presence by the formation of i^recipitates. They are also soluble in water, which fact has a direct bearing upon the dura- bility of cements made with the impure add." (Burchard.) The various preparations of phosphoric acid are proverbially unstable, and none more so than the metaphosphoric acid used in the formation of the zinc oxyphosphate cements. PrecixDitates are often thrown down in a few weeks after manufacture or crystallization takes place. The j)recipitates are in all j^robability metallic phosphates, while crystallisation may be due to imperfect conver- sion during the process of heating. These acids are all strongly hygro- scopic ; the metaphosx^horic acid being slowly converted into the common l^hosphoric acid by abstraction of water from the atmosx)here. It is there- fore imj)ortant that the liquid be kept tightly corked when not in use to prevent change taking x)lace in it, if the best results are to be obtained with the cement. Properties and Uses. — Zinc oxy^jhosphate cements possess certain properties which make them exceedingly useful in the daily practice of the dentist, the most important of which are : First, as a lining for large cavities with thin, frail walls it is far sui)erior to zinc oxychloride, by reason of its stronger adhesion to the walls of the cavity, thereby in- creasing their strength and lessening the danger from fracture, and its greater hardness, which makes it a better foundation for metal fillings ; second, as a temporary filling in devitalized teeth which have been placed ux)on probation, in vital teeth having large and very sensitive cavities, and in the deciduous teeth of children, by reason of its easy introduction, ready adaptability, and its evident obtunding effect ujoon hypersensitive dentin ; third, for sealing in arsenical dressings ; and fourth, for cementing crowns, bridges, orthodontic appliances, and inlaw's. As a conductor of caloric it possesses a slightly higher ratio than zinc oxychloride. On account of the strong affinity of metax)hosphoric acid for water it often causes jDain when first j^laced in sensitive cavities by abstracting the moisture from the dentinal tubuli, while if i)laced in con- tact with an exposed or nearly exposed pulp the j)ain is often excruciating. This may be obviated by lining the cavity with one of the quick-drying ethereal varnishes or by interi)os;ng a laj^er of softened gutta-percha. Zinc oxyphosphate, however, should never be used for fillings which approach the gingival margin or extend beneath it without guarding this vulnerable point with gutta-percha. Zinc oxyphosphate is readily dis- solved by solutions of lactic acid, and this is almost always iDresent at the crevices of the teeth, along the borders of the gingivae and in the inter- approximal spaces. Fillings thus guarded, if well made, will last from one to five years, and in favorable cases they have been known to do good service for a much longer j)eriod, while the operator will be relieved of the anxiety incident to the tendency of the material to disintegrate at the cervical margins when guarding is neglected. Mixing and Introducing the Cement. — As a preliminary to prepar- ing the cement for introduction into the prepared cavity the rubber dam 342 OPERATIVE DENTISTRY. should be adjusted, in order that perfect dryness of the cavity may be maintained during the insertion of the cement and the early stage of the hardening or setting process. In mixing the oxyphosphate cement one or more drops of the liquid, according to the size of the cavity to be filled, are placed upon the glass mix- ing-slab, and near it a quantity of powder ; with a spatula a portion of the powder is then drawn into the liquid and mixed by rubbing with the flat surface of the spatula, other portions being added a little at a time until a mass is formed of the consistency of soft dough, the surface being sticky or tachj, so that when it is applied to the dried surface of the cavity it will adhere or stick. Cements which are made so hard that they can be rolled in the fingers have not given, in the practice of the writer, as good clinical results either in hardness or wearing qualities as those mixed as above described. The instruments which are the most ai^plicable for the introduction and packing of the oxyphosphate cements are those generally used for intro- ducing amalgam fillings, the spatula-shaped instruments being the most useful. If the mix has been made of a sticky or tacky consistency, the final packing of the filling and the shai^ing of the surface will be more readily accomplished by covering the surface of the instrument with oil, vaseline, or glycerol, to prevent the material from sticking to it. The writer pre- fers the glycerol for the reason that it is just as good as the other sub- stances for preventing the material from clinging to the instruments, while it has the advantage of not leaving an unpleasant taste in the mouth. The rubber dam should not be removed until the filling has set suffi- ciently hard to j)ermit of finishing the surface. The finishing may be ac- complished with cuttle-fish disks, Arkansas stones, and burnishers. It has generally been thought that the process of crystallization was promoted by protecting the filling for some considerable time from the moisture of the mouth, and the manufacturers of these cements usually recommend covering the surface of the filling with some protecting substance, like sandarach varnish, or burnishing hot wax or paraf&n over it. The utility of such a procedure would seem to be questionable in the light of recent investigations upon the cements, conducted by Ames* and Wedelstaedt. Shrinkage and Expansion. — Ames thinks there is no advantage to be gained by protecting the cement fillings for an indefinite i)eriod from the saliva, as he found a distinct and radical difierence in the amount of shrinkage when the two classes of cements — viz., first, those modified by alkaline phosphates ; and second, those modified by non-alkaline phos- phates — were permitted to harden in a dry state ; but when the process of crystallization was allowed to take iilace with the mass subjected to water there was a marked modification of the amount of shrinkage, which was often changed to expansion in the second class of cements. ^'In the oxyphosphates wherein the phosphoric acid has been modified by alJcaUne phosphates only, the basic phosphate which is formed, and which '• Dental Cosmos, 1899. MANIPULATION AND INTRODUCTION OF PLASTIC FILLING-MATERIALS. 343 accounts for the hardening of the mass, is of a friable nature, and is of itself a porous material ; so that in agglomerating the crystals or granules of the zinc oxide it exerts no s^DCcial force which would result in a drawing together of the granules and make evident a shrinkage, at the periphery. " In the oxyphosphates wherein the acid has been modified by wow-alka- line phosphates, the basic phosphate formed has a glassy nature, and not only agglomerates, but agglutinates the zinc oxide granules. In the previous case the basic phosphate itself becomes porous in its crystal- lization ; while in the second case it is a glassy material which agglu- tinates the granules to such an extent as to cause a drawing of them towards a centre if the composition happens to give a tendency to a diminution of volume during the crystallization. This diminution of volume sometimes dej)ends on a lack of water of crystallization, which if present in the composition would give too rapid setting, but which if added to the crystallizing or hardening mass will be taken up and give the difference between a shrinkage and zero or an expansion. "In the first there is a diminution of volume which is not apparent, because the material forms a porous mass, and there is shrinkage towards an infinite number of centres instead of one, as in the second class. In the second class there may be diminution of volume in the dry state, and zero or expansion by furnishing extra water of crystallization." Wedelstaedt* in his investigations was surprised to find "that some of his experimental fillings of oxyphosphate would expand two millimetres beyond the cavity in which they were made, and was equally surprised to find shrinkage in some cement fillings when made in fresh teeth and tested in moisture. The aniline ran completely around the filling, leaving the axial wall of the cavity as well marked as though no cement filling had been placed in that cavity." Penetration of Moisture.— Wedelstaedtf discovered also that the oxyphosphate cements were readily penetrated by moisture, as was proved by the fact that out of more than thirty different specimens of cements only one was not penetrated from circumference to centre when subjected to the aniline test. The same was found true of the oxychlorides, for only one sample, " Justi's Acme," was not penetrated by moisture. The writer, in conducting a similar series of experiments, found but one form of zinc oxjqjhosphate cement that was impervious to aniline dyes. Specimen fillings made from the "Ames Metaloid," after being immersed in aniline for ten days, showed no penetration either at the margins of the filling or within the mass. Crushing Stress. — Wedelstaedt J also found that some of the oxyphos- phate cements would sustain a surprising amount of stress when thoroughly hardened, and that age^ up to a certain point, added very greatly to the strength of the filling. Six fillings were made in cylinders of the uniform size of two and a half by three and a half millimetres, and all made from the same cement and from one mix. These were tested in a dynamometer, two at the end of twenty-four hours, when it was found that at a pressure * Dental Cosmos, 1899. t Ibid. \ Ibid. 344 OPERATIVE DENTISTEY. of from eighty to ninety pounds they crashed to pieces. At the end of forty-eight hours two others were subjected to the pressure of the dyna- monieter, and sustained a stress of two hundred pounds before going to pieces. At the end of seventy-two hours, the two remaining cylinders were found to successfully carry a weight of from three hundred and fifty to ifoui- hundred pounds before crushing. Other fillings, tested ninety-six hours after they were made, carried over four hundred pounds of stress before going to pieces, which is a sustaining strength superior to that of the best-made amalgam or gold fillings. The best-made fillings of the former material, according to Black, crush at from three hundred and twenty- five to three hundred and sixty pounds of stress, while the fillings made from the latter material show a shortening of the mass under a stress of three hundred and fifty pounds of from two to fifteen per cent. Zinc Oxysulphate. — This x^reparation is in no sense a filling-material, but it is a valuable adjunct to the other materials for protecting and capping pulps which are nearly exposed. Zinc oxysulphate is composed of a powder consisting of one part of calcined zinc sulphate to two or three x)arts of calcined zinc oxide. The liquid consists of a solution of gum arable to which a small quantity of calcium sulphite has been added. The powder and liquid mixed together form a mass which sets quickly and attains considerable hardness. (Flagg.) It is non-irritating to sensitive dentin and to exposed pulps, a good non-conductor of caloric, slightly astringent, and seems to possess a pecu- liar conserving action ui^on the pulp not shared to an equal degree by any other material used for this purpose. For protecting nearly exposed pulps a thin paste is made of about the thickness of cream, which is carefully flowed over the bottom of the cavity and allowed to harden, — setting takes from five to fifteen minutes, — when it should be covered with a layer of oxyphosphate. In capping exposed pulps a tiny disk of writing-paper or other suitable material is dipped in the paste and quickly and carefully laid over the exposure and covered with a small quantity of the paste. When set oxy- chloride or oxyphosphate cement may be placed over it and the cavity lined with the same material, preparatory to the introduction of a metal filling or a porcelain inlay. The rubber dam should invariably be used, as the exclusion of all moisture is absolutely necessary to the success of the operation. VARNISHES. Varnishes are often used for lining cavities preparatory to the introduc- tion of the plastic fillings, especially of the zinc oxychlorides and oxy- phosphates, the object being to x>rotect the sensitive dentin and the pulp from the irritation sometimes induced by the action of the acids contained in the liquids of these compounds, and by the non-conducting quality of the varnish to lessen thermal shock. These varnishes are made by combining certain gums and resins with alcohol, chloroform, and ether, such as gum sandarach in alcohol, virgin rubber in chloroform, Canada balsam, copal, or dammar in ether, and MAXIPULATIOX AND INTRODUCTION OF PLASTIC FILLING-MATERIALS. 345 trinitro-cellulose in methyl alcohol. These solutions should be made thin enough to flow readily, and be applied to the cavity by a pellet of cotton. As soon as the varnish has dried the cement lining may be introduced, the enamel margins having first been freed from any portion of varnish. The same precaution must be observed in freeing the enamel margins of the cement before the permanant filling-material is introduced, as careless- ness in this regard is bound, sooner or later, to result in a leaky filling from disintegration of the film of varnish or of the cement allowed to remain between the filling-material and the enamel margin. Some operators are in the habit of lining with varnish all cavities that are to be filled with gold or amalgam, claiming for this method that it greatly lessens thermal shock by sealing the open ends of the tubuli and interposing a non-conducting film between the sensitive dentin and the filling, and prevents discoloration when amalgams are employed. The same method is pursued by these operators when filling with gutta-percha, especially when employing the "high heat" material, as the adhesiveness of the varnish in retaining the first pellets in x^osition is considered an added advantage of the varnish lining. CHAPTER XXI. INLAYS. Definition. — As applied to deutal surgery, an inlay is a piece of any substance, like gold, glass, porcelain, etc., which is inserted in a cavity jjrepared to receive it, or attached to a portion of the crown of a natural tooth. The distinction between an iyilay and a filling being that the inlay is inserted into the cavity in a solid piece and retained in its l^osition by means of cement, while a filling is introduced in numerous small pieces, which either cohere or weld to make a solid mass, or are held together by mechanical pressure or the interlacing of particles, the com- pleted filling being held in place by the adaptation of the material to the walls of the cavity, assisted by the retentive form which has been given to it. The dream of the truly scientific and artistic dentist has always been the discovery of a material with which to restore those portions of the natural teeth which have been lost bj^ the disintegrating effect of dental caries, or by traumatic injury, that would be indestructible in the secre- tions of the oral cavity, protect the tooth against the further ravages of caries, restore its original beauty of form, color, and translucency, and at the same time place it in a position to perform all of its functions in a normal manner. The art of the porcelain- worker has already reached such perfection in the construction of artificial crowns that the visible portions of such restorations are so natural in their appearance as to be beyond detection except by a critical examination. The success in this direction has stimulated the desire to successfully restore by the same means such portions of the tooth crown as have been lost by disease or accident. In studying the history of primitive dental art, it will be found that the idea of restoring lost portions of the teeth by the introduction of inlays is as old as the art itself In the early Greek epoch, teeth were filled with metal inlays by driving solid pieces of lead into the cavity ; while doubtless at a still earlier date jade or graystone was used for the same purpose, as found in the central incisors of the skull of a man of an extinct race, discovered at Copan, Honduras, by Professor Owen, a few years ago, and which is now to be seen in the Peabody Museum of Har- vard University. Inlays made of various materials have been emi)loyed by the modern dentist, but none possess in so high a degree the many requisites for the ideal filling as does porcelain. Inlays have generally been used in two classes of cavities only,— viz., in very large cavities in the bicuspids and molars the walls of which were too frail to support gold fillings, and in cavities located upon the labial 346 INLAYS. 347 surfaces of the anterior teeth when it was desirable to use a material that would be less conspicuous than gold, and which would harmonize with the color of the tooth in which it was inserted. Metal Inlays. — Gold has been recommended for making inlays for large compound cavities in the bicuspids and molars, and is still used for this purpose by some dentists as a saving of time and strength to both operator and patient. These inlays are made in two ways. One by swaging gold plate over a die made from an impression taken in wax, gutta-percha, a modelling compound, or by burnishing gold or platinum-foil to the walls and margins of the cavity ; and the other by fusing gold into a matrix made in sand and plaster mixed with asbestos modelled from a similar impression. The finished inlay is then cemented into place with zinc oxyphosphate cement or gutta-percha. In order to secure the swaged inlay against dislodge- ment a retaining loop should be soldered to its under side, or pins may be attached, which in devitalized teeth may be made to enter the pulp-canals. The fused inlay should be roughened upon the surfaces which come in con- tact with the cement for the same purpose, or headed pins may be attached. Dr. C. L. Alexander describes a method of making gold inlays* which has many good features and may frequently be applied in cases when the restoration of contour by the means of porcelain inlays might, on account of the severe strain to which this material would be subjected, and its liability under sudden and excessive stress to be fractured, be of question- able utility. The method is equally applicable to vital and pulpless teeth. In the former, anchorage is secured by short posts set in such positions as not to infringe upon the pulp, while in the latter the pulp -canals are freely opened and longer posts so set as to penetrate the canals, as shown at A, Fig. 466, the tooth being prepared as represented at A. ^^^- '^*^^- Platinum plate, No. 40 gauge, is then thoroughly annealed and a piece cut from it of proper shape to cover the lingual surface of the crown and extend over the mesial and distal surfaces. This is bent into shape, fitted to its place, and a hole punched in it over the open- ing to the pulp-canal ; the post is then passed through the opening and into the pulp-canal, being long enough to project a little distance beyond the outer surface of the plate. A small piece of soft modelling compound is then moitlded over the plate and the projecting end of the post, which when hardened holds them in their relative positions. The piece is then invested in sand and Showing details of the process for making cast fill- ing for incisor. (After C. L. Alexander.) A, post with plate adapted ; B, restored contour in wax ; C, the contour invested ; D, cast contour detached ; E, E, the finished restoration. * Dental Cosmos, October, 1896. 348 OPERATIVE DENTISTRY. plaster, and the post soldered to the plate with pure gold. It is then returned to the tooth, the platinum plate carefully burnished to the surface of the crown, and the edges are trimmed to the desired shape. An im- pression and bite are next taken as for making a crown and set up in an articulator with sand and plaster. After removing the modelling com- pound the contour of the tooth is restored in hard wax upon the platinum base. A piece of No. 60 gold-foil or platinum-foil is then burnished over the wax, covering it except at one wall, preferably the lingual surface. The whole tooth is then cut from the model and invested, care being taken to completely cover it except at the surface of wax not covered with the foil. When hardened the wax Fig. 467. Fig. 468. is boiled out, leaving the metal lining the matrix, which acts as a carrier for tiie: metal which is to be fused into it. The matrix is then fluxed, filled with pieces of twenty - two - carat solder, and the investment thoroughly heated, when with a fine blow- pipe flame directed into the matrix the solder is flowed, more being added until the matrix is full. After it is re- moved from the investment the casting is finished and cemented into its position ; the final polishing to be done after the cement has thoroughly set. Fig. 467 shows the method of restoring a raesio-morsal angle in a vital tooth. Fig, 468 shows the restoration of the lingual cusp and morsal sur- Restoration of incisor by RestxDration of molar cast filling. by cast filling. (After (;. L. Alexander.) Fig. 469, flBUll Fig. 470. Front and back ^n'ews of an incisor restoration and cast tilling for molar. (After C. L. Alexander.) Foil matrix invested. Cast filling for molar. (After C. L. Alexander.) face of a devitalized bicusj)id. Fig. 469 gives a labial and a lingual view of incisor restoration and cast filling for molar as adajjled to vital teeth. Fig. 470 shows a more extensive restoration of a molar tooth. This method may also be adapted to the making of abutments for carrying pieces of bridge-work, as shown in Figs. 471 and 472. Amalgam inlays were quite extensively used a few years ago in Ger- many for restoring the contour of the posterior teeth. These were fur- INLAYS. 349 nished by the dealers in several different shapes and sizes, and were set in position by means of freshly prepared soft amalgam. The only advantage of amalgam inlays is the ease with which they are made, but aside from Fig. 471. Fig. 472. Method of bridging with inclined abutment. (After C. L. Alexander.) Bridge with cast filling abutments. (After C. L. Alexander.) this they have nothing to recommend them, and are in no respect as good as amalgam fillings made in the usual waj'. Porcelain Inlays. — Porcelain is the only material which has so far been discovered that can be made to imitate natural tooth-structure, and this art, in the manufacture of artificial teeth, has been carried to such perfection that when proj)erly arranged and mounted they are capable of deceiving any one who is not a professional expert in the art. For this reason the artistic dentist has always looked forward to the time when por- celain could be substituted for gold and amalgam in filling teeth in the anterior j)art of the mouth and in conspicuous locations in the bicuspids and molars. Various efforts have been made in the past to introduce porcelain as a material for filling teeth, but tlie difaculties which have always, until very lately, surrounded the operation have deterred all but a very few practi- tioners from attempting the task. The earliest method of using porcelain as a filling for decayed teeth was to prepare the cavity— usually in the labial surface of an anterior tooth — with slightly flaring walls or bevelled margins, and then to grind a piece of a porcelain tooth having a color that would match that of the tooth in which the inlay was to be inserted until it would fit the cavity, and re- taining it in situ with zinc oxychloride cement, or by packing gold around the edges. The writer has seen one such inlay, which was inserted by the late Dr. W. W. Allport, that had done service for more than thirty years, and was still as perfect as upon the day in which it was completed. The method of grinding adopted by the earlier operators was to smear the margin of the cavity with a water-color, generally red, and then to place 350 OPERATIVE DENTISTRY. the inluy in Uie cavity, and after removing it grind those places which had received the color as is practised in grinding gum sections to fit the rim of a gold i)late. Another and perhaps better method of fitting such inlays is to take an impression of the margin of the cavity—after it has been prepared to receive tile inlay— with a piece of No. 20 tin-foil, by placing it over the cavity and with a soft rubber eraser or a rubber bottle-stopper pressing the foil firmly until the margin is sharply marked. This impression should then be carefully trimmed to the line of the cavity margin, and the pattern glued to the upper surface of the piece of porcelain tooth that is to become the inlay to serve as a guide in the grinding. The section should be cemented with shellac to a piece of wood on its under surface to assist in holding it during the process of grinding. With care, patience, and unlimited time at the disposal of the operator a perfect fit may be Fig. 473. Fig. 474. Q © 00 Porcelain stoppers. obtained, but only after repeatedly trying the inlay in the cavity. The final fitting of the inlay may be ex- pedited by cementing with shellac the end of a short section of wire or a broken excavator handle to its upper surface, as this overcomes the difficulty in holding the section during the pro- jj^i^y ^.^^^ cess of grinding, and offers a ready means of inserting and removing the section from the cavity. The time consumed in this process of fitting inlays is so great that few people are willing to sufficiently remunerate the dentist to make it a profitable or popular operation. As a means of overcoming some of the difficulties attending this great time-consuming operation the dental porcelain manufacturers have placed upon the market ready-made porcelain inlays of different shapes, sizes, and colors, known as porcelain stoppers (Fig. 473). These stoppers can- not be used until they are ground to fit the cavity, which may be done after the manner just described. Another method is that devised by Dr. G. H. Weagant, which consists of cutting inlays from artificial teeth or inlay rods (Fig. 474) by the aid of especially devised trephines of five different sizes (Fig. 475), made of copper and charged with diamond dust. These trephines are to be used in conjunction with How's inlay burs (Fig. 476), which correspond in size to the trephines. After the decay has been removed from the cavity, a bur is selected from the How set which will be large enough to include the utmost limits of the cavity, and the final preparation of the cavity completed with it. A trephine is next selected which corresponds in size with the How bur. and a section cut from an artificial tooth, preferably of English make, INLAYS. !51 whose color matches that of the natural tooth. This inlay is then cemented w sihi with zinc oxyphosphate, and after the cement has set any projection of the inlay may be dressed off with fine Arkansas stones, or diamond disks or burs. If English artificial teeth are used, or those of Fig. 475. Fig. 476. ^\■eagaut trephines. 11 How inlay burs, the Consolidated Dental Manufacturing Company, the inlay will receive a fine polish^ and, not being of porous material, it will show no tendency to discoloration. This method is, however, open to one very serious objec- tion, — viz,, the necessity of sacrificing a large amount of sound dental tissue in order to give a circular outline to the walls of the cavity. For this reason, principally, the method has never been employed to any great extent. A very beautiful and close joint may be made by this method if the joint is ground while the inlay is in situ. This may be accom- plished by cutting the inlay a size larger than the cavity which is to receive it, and slightly tapering the section until the lower end will freely enter the margins of the cavity. It may then be cemented to an engine mandrel, and ground into place by revolving it in the cavity, using pul- verized pumice moistened with water as the grinding medium, just as the plumber grinds the joint of a water-cock. Glass Inlays. — Herbst, of Bremen, in 1887, introduced a system of making inlays by fusing powdered glass in a matrix of platinum-gold foil, made by pressing the foil into the prepared cavity with pellets of cotton and burnishing it to the margins. The powdered glass, which was made from Venetian glass beads, and sold under the names of "Eichter's Glasmasse" (glass-body) and Meyer's and Herbst' s Venetian Enamel, was furnished by the dealers in several shades, so that it was possible with care to match the color of the natural teeth fairly well, and when the inlay was cemented in situ it presented an appearance which very closely imitated the vitreous surface of the enamel. The method of fusing the glass was to hold the matrix, which had been filled with the material, in the flame of a Bunsen burner or alcohol lamp. In order to render the glass fusible at so low a degree of heat it was neces- sary to reduce the melting-point by the introduction of a large amount of flux. This rendered the material soft and porous, so that it was unable to withstand the action of the oral secretions or the attrition of mastication, and soon lost its satisfactory appearance, first becoming opaque, then dis- 352 OPERATIVE DENTISTRY. colored, and later almost black, while the surfaces which came in contact with occluding teeth disintegrated and wore away like zinc phosphate cement. Tlie invention of thjp metalic matrix by Dr. William Eollins, of Boston, and described by him in a paper read before the Society for the Advance- ment of Oral Science, June, 1880, though almost forgotten for nearly two decades, has, nevertheless, the enviable distinction of having led the way to, and made possible the construction of, artistic and perfect fitting porce- lain inlays. Another important step towards the perfection of this process was the invention by Dr. C. H. Land, in 1884, of the gas furnace. Before this time the dentist who desired to make a porcelain inlay by fusing the mate- rial in a metal matrix was hampered in his work by being obliged to depend upon the slow-heating and cumbersome coke furnace. This invention was followed by the Downie crown furnace, which was still smaller than the Land furnace, and later by the electric oven of Custer and the electric furnace of Mitchell (Figs. 477 and 478). Since the introduction of electricity as a means of heating furnaces for the firing of porcelain the size of the apparatus has been greatly reduced, and the time consumed in heating the furnace and firing the porcelain has FiQ. 477. FiQ. 478. Custer electric oven. Mitchell tlcttrii furnace been curtailed to a few minutes, while the danger from changing the color of the material by the presence of gases has ceased to cause anxiety, and the noise, dirt, and hard labor incident to working the foot-bellows of the gas furnace have all been done away with. Porcelain.— Until quite recently the porcelain used for making inlays was of the high-fusing grade, the Close or Downie porcelain body generally being employed. These bodies require a platinum matrix in which to fuse them, as the fnsing-point is about 2500° F., which is considerably higher than the fusing-poiut of pure gold. INLAYS. 353 The Downie bodies are furnislied in twenty- four different shades of color, which makes it possible, when skilfully and artistically combined, to reproduce any shade of color to be found in the natural teeth. These porcelains are admirably adax)ted for crown- and bridge- work, but they have never been extensively used for inlays, for the reason that a platinum matrix is I'equired in which to fuse them, and this material is so stiff and harsh, even when annealed in a furnace, that it cannot be readily adapted to the cavity walls and margins, and therefore does not furnish so reliable a means of taking an impression of the cavity as does gold-foil, and fail- ures in the fit of the inlay are more liable to occur. For this reason vari- ous efforts have been made to produce a low-fusing porcelain that could be fired in a gold-foil matrix, and which at the same time would not be po- rous, would not change its color in firing, would be susceptible of taking a polish after being ground, would not disintegrate or change its color in the mouth, and would have sufficient strength to withstand the stress of mastication. For several years Dr. E". S. Jenkins, an American dentist, of Dresden, Germany, experimented with porcelain, and consulted the best chemists and expert porcelain- and glass- workers of Europe in an endeavor to iDer- fect a low-fusing porcelain which would fulfil the requirement of the den- tal practitioner for inlay work. In March, 1898, he announced to the members of the American Dental Society of Europe — before whom he had frequently discussed the question of porcelain inlays, and had re- 13orted from time to time the i^rogress of his exiDerimeuts — that he had finally succeeded in his undertaking ; that he could now pronounce his work finished, and desired first to announce his discovery to them, and then to the profession at large. The announcement attracted universal attention, and dentists everywhere, both in Europe and America, began experiment- ing with Jenkins' s porcelain enamels and his method of making inlays. These porcelains are very finely ground, and are furnished to the pro- fession in eighteen different color shades, whites, blues, yellows, and browns. Dr. Jenkins says of his porcelain enamel, that he took as his model the Ash & Son's tooth, and tried as far as jDOSsible to imitate the fine texture and character of this porcelain tooth body, but so changed its composition as to make it fuse at a degree of heat which would allow of its being fired in a gold-foil matrix. Great difficulty was experienced in obtaining colors which would not change during the process of firing, but he finally succeeded, so that there is absolutely no change at any degree of heat which will not melt the gold-foil matrix. The permanency of the color in the fluids of the mouth he believes is scientifically certain ; the material is not acted upon by any chemic substance except hydrofluoric acid, and is so hard and tough that it will withstand the stress brought upon it in mastication without appreciable attrition or chipping, and retain its polish under the use of the tooth-brush and powder. Ash & Son, of London, have j^erfected a high-fusing body in six shades, with two shades of enamel, one dark, the other light, which Dr. J. Leon Williams very highly recommends in an article on '^ Ceramic 23 354 OPERATIVE DENTISTRY. Art in Eestoration of Teeth" (Dental Cosmos, Kovember^ 1899). They Lave also prepared a low-fusing body in seven colors, and one enamel, which he tliinks are in no way inferior to those prepared by Dr. Jenkins. The Consolidated Dental Manufacturing Company of l^ew York have also prepared and placed upon the market high-fusing and low-fusing porcelains made after suggestions of Dr. Joseph Head, which seem to be in every way equal to the Jenkins and Ash bodies. METHODS OF MANIPULATION. The first important consideration in making porcelain inlays is a Judicious selection of the cases in which this method of filling teeth is to be employed. It is not, for instance, applicable to cavities in the distal sur- faces of the second and third molars, for the reason that in such locations a perfect impression would be difficult or well-nigh impossible to obtain, and consequently an inlay could not be constructed which would be as good as a metal filling inserted in the usual manner. In all other locations in the mouth, with skill and patience, satisfactory inlays may be inserted. The locations, however, in which they are most applicable are : 1. In cavities upon the labial and buccal surfaces of the incisors, cus- pids, and bicuspids. 2. In large cavities located upon the approximal surfaces of the six anterior teeth and the mesial surfaces of the bicuspids. 3. In large cavities involving the mesio-morsal surfaces of the first molars. 4. In large morsal cavities in any of the molars when the walls are thin and the pulp nearly exposed. One of the great advantages of porcelain as a material for stopping carious teeth is its low conducting power of caloric, which greatly lessens the shock incident to the sudden changes of temperature so constantly taking place in the mouth, and which sometimes makes a metal filling unendurable. Preparation of the Cavity. — In j)i"eparing a cavity to receive a porcelain inlay, the same degree of care should be exercised in removing the decayed and infected dentin that would be expended upon it if it was to receive a gold filling. The shaping of the cavity is an important feature, and too much care cannot be expended upon it. In general terms it may be stated that the cavity should be formed with flaring walls — in other words, cui^-shaped — without undercuts, and the enamel margins slightly bevelled outward, so that when the foil is removed and the inlay is inserted it will set into the cavity the thickness of the matrix and fit tightly at the margins. In preparing the enamel margins all corners and sharp angles must be removed, the outline of the cavity following graceful curves. The bevel must not be too great, as this would give a thin edge to the inlay and might cause it to chip. In restoring a mesio-morsal or disto- morsal angle of an incisor, it is best to leave the margin square at a right angle to the morsal edge, as by this method there is less danger of the enamel edge being fractured. The margins of all morsal cavities should be prepared in the same manner. INLAYS. 355 Preliminary separation of the teeth is an essential in inlay work, as plenty of space must be secured if a perfect impression is to be obtained and the normal contour restored. Taking the Impression. — A perfect impression is a sine qua non, without which every effort at making a perfect fitting inlay will prove futile. The materials which are employed for this purpose are platinum- and gold-foils, platinum IsTo. 30 being used for high-fusing bodies, and gold IS"©. 30, and occasionally No. 40, for low-fusing bodies. Several methods have been suggested for taking impressions of cavities in teeth which are to be filled with porcelain inlays. The simplest is to cut a piece of foil a little larger than the cavity of which an impression is desired — if j)latinum-foil is used, this should be thoroughly annealed in a furnace for several minutes and allowed to cool slowly — and j)lace it over the cavity, and then with a ball of cotton, bibulous paper, or amadou, held in a pair of slender curved foil-carriers, gently press the foil into apiDOsition with the walls of the cavity, smoothing out the wrinkles towards the margins, l^ext pack the cavity with small pieces of amadou, holding them in position with an instrument held in the left hand, while with a ball-burnisher the enamel margins are well defined. The amadou is then removed, and the foil matrix jarred out of the cavity by tapping the tooth with the foil-carrier, or by carefully teasing it out with a curved pointed explorer. Sometimes the matrix will come away with the amadou packing, but if it has to be removed by the means just suggested, a small receptacle should be held under the tooth to receive it when it falls. A small sugar-spoon or a small pill-box will answer the purpose. The suri^lus foil is then trimmed off a little distance from the line of the enamel margin, and the matrix returned to the cavity and moulded as before. The greatest of care must be exercised not to change the shape of the matrix after it finally leaves the cavity. For this reason some opera- tors recommend investing the matrix in sand and plaster, or in powdered asbestos and plaster. The writer combines the latter materials in equal parts, which form a sufficiently firm and stable investment for the j)ur- pose. The investing material should be mixed quite soft, so that when the matrix is laid upon its surface it will embed itself up to the described margins of the cavity. Some operators think the platinum matrix is sufBcieutly rigid after being fitted to the cavity to need no supporting investment, and this is doubtless true when heavy foil is used, but not so with light-weight foil, and in any case the investment removes the anxiety of its becoming changed in form, and also insures a perfect fit if it has not been altered before it is invested. As soon as the investment is dry the matrix is ready to receive the porcelain body. Another method is to fill the matrix with moderately hard wax or gutta- percha before removing it from the cavity, and then, turning it bottom side up, invest it. After the investment has hardened, the wax or gutta-percha is removed by boiling water. The same methods are employed for taking an im^Dression with gold- 356 OPERATIVE DENTISTRY, foil, but greater care is necessary in removing the matrix not to alter its shape. Gold- foil, however, has the advantage over platinum that it gives a sharper impression of the walls and margins of the cavity, and therefore insures a more perfect fit. A tear in the foil at the bottom of the cavity is of no consequence, as the body will not pass through it, but a tear oc- curring at the margin ruins the fit of the inlay. Dr. Jenkins recommends investing the gold-foil matrix in simple pow- dered asbestos mixed with water to a thick creamy paste. This investment will be found to be sufficiently strong for the purpose, and it can be fired any number of times without cracking. As soon as the investment has been dried— and this should be done slowly — the matrix is ready to receive the'body. Dr. Van Woert recommends taking an impression with inlay cement, such as that manufactured by the Consolidated Dental Manufacturing Com- pany. The method is as follows : Mix the cement to a stiff paste that can be manipulated with the fingers, press it into the cavity, —which has been previously anointed with vaseline, — and allow it to harden, care being taken to use a mass sufficient to overhang the cavity margins in all direc- tions. When hard, trim sufficiently to allow it to be removed from the cavity without fracturing it. It is then embedded in a piece of warm model- ling compound with the impression of the cavity uppermost and the edges free. Then cool in ice-water, and make a counter-die of the cement im- pression in softened modelling compound. When cooled, this will be found sufficiently hard to permit of swaging No. 30 gold-foil to the exact shape of the cavity in the tooth. The matrix thus fashioned is to be re- moved and invested in moistened powdered asbestos as above described. Dr. Van Woert claims for this method a more perfect fit, inasmuch as the matrix was made over a die which gives the exact outline measurements of the cavity, and does not leave a deficiency equal to the thickness of the matrix. Packing the Body and Firing. — The selection of the color for the inlay must be done with the shade ring which accompanies the porcelain powders, and with the tooth in the moist state. Drying a tooth changes its color very materially. The writer selects a porcelain tooth that matches the color of the tooth to be filled, and uses this as a guide while baking the inlay. First ascertain the basal color, and then any tone may be given to it by a proper combination of the other colors. The body may be mixed either with distilled water or absolute alcohol. In mixing the body a consistency of soft dough should be obtained. It is then placed in the matrix with a small spatula, and settled into place by tapping the pliers that hold the platinum matrix or the tray containing the invested gold matrix. In packing the first instalment of the body it should not be allowed to come quite up to the margins of the matrix. If the matrix is filled at the first firing, the contraction of the material is very likely to warp the matrix and spoil the fit of the inlay. This is now placed in the furnace and fired until a glaze appears upon the surface, when it is removed, cooled, and returned to the cavity, and the edges again care- fully burnished to the margins. INLAYS. 357 The partially filled matrix is again removed and, if of gold, invested as before, and the second instalment of body added to that already fired, bringing it U]) to the edges and giving it the desired contour, but care- fully removing with a camel' s-hair pencil any portion of body which may have projected beyond the line of the enamel margins, when it is again fired. It is a safe plan to replace the inlay in the cavity after the second firing and study its contour ; if this is not quite right, more material can be added and the piece again fired. After the inlay has cooled the foil matrix may be peeled off by starting it from the edges first and working towards the centre. If it is peeled towards the edges, chipping is likely to occur. Any particles of the foil which remain may be scraped off with an excavator, and it is imjDortant that all be removed, or a perfect fit of the inlay will not be secured. In building large contours or restoring the angle of an incisor, a chip of a porcelain tooth of the jiroper color may be placed in the matrix and the body built around it. Such cases, however, require to be heated and cooled more slowly than small inlays, or otherwise there is danger, from the sudden expansion and contraction, of cracking and checking the piece. A safe rule to follow is to make all inlays a trifle darker tlian the tooth when inserting them in the labial and buccal surfaces or the approximal surfaces of the incisors, as they are less conspicuous if a little darker than when a little lighter. In approximal cavities in the bicuspids and molars lying well in the shadow of the tooth the inlay should be a trifle lighter in shade than the tooth, as the shadow makes them appear darker. Williams suggests that the contraction which occurs in firing large inlays, which often warps the matrix and thus destroys the accuracy of the fit, may be obviated by mixing the porcelain paste to the consistency of soft putty, and building a '"'ring of this putty around the entire circumference of the cavity in the matrix, leaving the centre free and empty. In melting a porcelain paste it naturally shrinks towards the largest mass of its own body, or towards the centre of the mass. If, then, this centre be removed, we should naturally expect the mass to shrink towards the circumference, and this is precisely what happens when manipulated as directed. The matrix always comes out from the first baking with the porcelain everywhere firmly melted to the walls of the matrix. ISTor will it ever start from this position at any subsequent baking unless it is very much overheated." Setting the Inlay. — After the foil matrix has been removed, retain- ing grooves should be cut at opposite points upon the under side of the inlay, in order that firm attachment may be secured to the cement, or the inlay may be embedded, f\ice downward, in a piece of warm base-plate wax and hydrofluoric acid applied to the back, and allowed to remain for about five minutes. On carefully washing the inlay with water it will be found that the acid has attacked the surface of the porcelain, removing the gloss, roughening the surface, and giving it the appearance of ground glass. To this surface the cement will adhere with great tenacity, preventing the inlay from being dislodged. The edges of the inlay will usually present a slightly thin, jagged ap- pearance, as the result of an overflow of the porcelain during the pro- 358 OPERATIVE DENTISTRY. cess of firing ; this should be carefully smoothed off with cuttle-fish disks or Arkansas stones. The inlay is then secured in place by setting it in zinc oxyphosphate cement. Any ordinary cement having a finely ground powder, like the Justi or Harvard, will answer the purpose, but these are improved by grinding in a mortar until the powder is impalpable. Coarse powders do not give good results, as the particles prevent a close approximation of the inlay with the walls of the cavity, thus spoiling an otherwise good fit. An inlay which fits perfectly, and which matches the color of the tooth, forms a joint which is almost imperceptible to the unaided vision. The cement should be mixed to the consistency of cream and spread evenly over the floor and the walls of the cavity. The inlay is then placed in position by means of the spatula, which should have a tiny bit of cement on its surface to cause the inlay to adhere to it, and then pressed home. Pressure should be maintained until the surplus cement has had time to escape around the margins of the inlay. In approximal cavities, after the inlay has been inserted, a wooden wedge may be placed between the approximating teeth to support the inlay during the setting of the cement, or cotton and sandarach varnish may be used for the same purpose and allowed to remain for twenty-four hours. The wedge may then be removed, and any projection of the inlay beyond the surface of the tooth dressed off with Arkansas stones or cuttle-fish disks. Inlays made from the porcelain furnished by Dr. Jenkins, Ash & Son, or the Consolidated Dental Manufacturing Company, will take a polish after being ground equal to Ash & Son's artificial teeth. A zinc oxyphosphate cement has recently been placed upon the market by the Consolidated Dental Manufacturing Company which has been pre- pared with especial reference to setting inlays, and is known as ''inlay cement." Each box contains a bottle of liquid and four bottles of powder, representing the four basal colors used in the making of the inlays. It is therefore possible with a little care to match the color of the inlay. The powders are very fine, and form, when mixed with the liquid, a very -smooth and fine-giained mass which does not set too i^apidly and makes a very hard and resistant cement. The cement forming the joint of the inlay should be protected from moisture for a few hours by coating it with sandarach varnish, melted parafQn, or chloro-percha. In finishing the inlay the stones and disks should be run in a direction from the edge to the centre, and never in the reverse direction, as there is danger of chipping the edges of the inlay if they are run in a direction from the centre to the edge. The final polishing may be completed with pumice and chalk. CHAPTER XXIL DENUDATION OH EROSION OF THE TEETH, AND ATTRITION OR ABRASION. Definition. — Denudation (Latin, denudare, — de and nudare, nudatum, — to lay bare), the condition of a part deprived of its natural coverings, whether by wounds, gangrene, or abscess. It is particularly applied to the bones when deprived of their iDcriosteum, and to the teeth when they lose their enamel or cement substance, or when the gums recede from them and their alveoli are destroyed. Erosion (Latin, erodere, erosum, — e and rodere^ — to eat away), the action of a corrosive substance, or the gradual destruction of a part by a substance of that kind. The term is often employed in the same sense as ulceration. It is a molecular disintegration of tissue caused by the action of some corroding agent. Various terms have been applied to this disease, such as denudation, erosion, surface wear, abrasion, and atrophy. Denudation or erosion of the teeth is a disease which attacks these organs, beginning with the enamel and gradually involving the subjacent dentin without any of the appearances or characteristics of dental caries. It consists of a gradual wasting away of the enamel and dentin, generally upon the labial and buccal surfaces, most often beginning with the incisors, though it may attack the other teeth first, and may involve all of the teeth to the second molars. It usually begins at the gum, forming depressed plains, cavities, or grooves, which follow the curves of the gum lines. They are as evenly and smoothly cut as though made with a file or disk, are highly polished, perfectly hard, and many times absolutely free from discoloration. The surface of the groove is generally quite sensitive, sometimes ex- quisitely so, causing the patient much uneasiness and pain. Occasionally the process begins at numerous irregular points on the labial surface, which extend, and after a time coalesce, involving the loss of the entire enamel wall of this surface. The disease progresses in rare cases as far as the pulp, laying that organ bare, while in the majority nature pro- vides against it by filling up the pulp-chamber with secondary dentin and thus protecting it from exposure. In other cases, after progressing to a greater or less extent, it seems to become self- arresting. The rapidity with which the disease progresses is also variable. In some cases the loss of substance will be so slow as to require ten, fifteen, or twenty years to reach the pulp-chamber, in others only a little more than as many months. The superior teeth are much more liable to be attacked than the inferior, though cases are quite common in which both are affected, but the writer has never seen the lower teeth destroyed to the 359 360 .OPERATIVE DENTISTRY. same extent as the upper. The bicuspids are most often the seat of the disease when located in the lower jaw. Causes.— Upon the question of the causation or etiology of the dis- ease there is a great variety of opinions. Up to the present time no definite conclusion has been reached by investigators as to the real factors of its etiology, and our knowledge of the subject is very unsatisfactory indeed. John Hunter was the first writer to notice and describe this disease. He named the disease '^ decay by denudation," and thought the disease was inherent in the tooth itself, and stated that he had seen cases where it appeared as if the outer layer of dentin had been destroyed first, and that the enamel afterwards broke through for want of support. This theory is evidently erroneous, for no such phenomenon occurs in this disease. He has doubtless confounded it with that form of caries in which the enamel becomes partially decalcified in spots and permits the pathologic condition to extend to the subjacent dentin, when after a time they break away together, leaving a shallow cavity more or less irregular in form, but lacking that smooth, polished condition which always attends a case of true denudation or erosion. Bell dissented from the views of Hunter, but expressed himself at a loss to explain the cause of the disease. He suggested, however, that the cause might be one of faulty develoj)ment of certain concentric portions of enamel, which would render such portions more liable to mechanical abrasion or other injury than the rest. If such were the true explanation we should expect to see the grooves extending completely around the necks of the teeth, but this condition never occurs, and yet certain portions of enamel may, as he states, be faulty in their development, but not necessarily, however, extending com- pletely around the tooth, and thus predispose such teeth to the action of solvent agents, as is believed to be the case in dental caries. Fox in writing upon the subject frankly admitted that he was unable to assign a cause for the disease, but thought that it was dependent upon some solvent property of the saliva. If the saliva contains the solvent which is responsible for this disease, we would expect to find all the surfaces of the teeth equally affected, for they are always more or less in contact with it. The inferior teeth are completely bathed in the saliva, so that if this suggestion was correct the lower teeth would be most often affected, while clinical experience teaches the very opposite to this. Wedl describes the disease and classes it among the atrophies, but makes no attempt to account for its peculiar manifestations. He calls at- tention to the fact, however, that sometimes the mucous membrane of the cheeks and lips is raised into a fold opposite the dental arches, and sug- gests that it may be well to consider, in future cases, whether any relation exists between the defects upon the necks of the teeth and these folds or ridges. These folds or ridges the writer has noticed many times, but they are by no means a constant accompaniment of the disease, and when such instances have occurred he has been inclined to consider it a result rather than a cause of the disease. DENUDATION OR EROSION OF THE TEETH. 361 Salter calls the affection '^ surface wear," and ascribes it to friction of the lips, cheeks, and tooth-brush. The surfaces of the teeth attacked are those usually reached by the tooth-brush, and by many the disease is thought to be one of mechanical origin entirely ; but this cannot be the case, for often the grooves or cavi- ties will reach around the teeth mesially and distally to points impossible to be reached by the tooth-brush or by folds of the mucous membrane of the lips or cheeks. The break in the tissue is also, in some cases, so decidedly undercut as to prove conclusively that such a condition could not have been caused by the friction of the tooth-brush. Tomes also observed a case of the disease where the patient rarely or never used the tooth-brush, and Mr. Harrison reported a similar case at the meeting of the Odontological Society of Great Britain in May, 1870. But the most conclusive argument against the me- chanical origin of the disease was furnished by Dr. Murie in a paper read before the same society at its meeting held in June, 1870, in wliich he related the fact of having found a sea lion (the Otaria jubata) whose teeth showed the results of this disease to a very considerable extent. The posi- tions most notably affected were the sides of the teeth where friction would be reduced to the minimum ; the tusks or great cuspids were most conspicuously affected by the disease. Tomes thinks this condition, ^'at least in so marked a degree, is not common among seals, but has seen an approach to it in the teeth of several specimens of different species, ' ' and he further says that in the museum of the Eoyal College of Surgeons may be seen the skeleton of a seal in which this condition of the teeth is well exemplified, some of the teeth being deeply grooved in positions not exposed to friction. Coleman * is inclined to the opinion that mechanical attrition is among the possible causes of the affection. In discussing the question of the presence of the disease in seals, he points out the fact that some seals are known to be in the habit of taking stones in their mouths, and very prob- ably sand also ; while hard fish-scales are frequently in their mouths. Their long and flexible tongues are also capable of being swept over the surfaces of these eroded teeth. It is not difficult, therefore, to suppose that by these means the surfaces of the teeth may be worn away. Although there is some uncertainty still resting upon the subject, and it is diffi- cult to account for, still he thinks from the foregoing that the question of mechanical attrition cannot be fairly ruled out as not being among the possible causative factors in these animals. Bland Sutton thinks there must be some association between erosion of the teeth and defective development. In a paper upon comparative dental pathology, t after referring to the condition of erosion in seals, he calls attention to the reduced dentition of the elephant seal (the Macrorhinus coninus) whose peg-shaped molars present a groove around the entire cir- cumference, which is perhaps caused by erosion, and also to a skull of the * Transactions International Medical Congress, 1881. t Transactions Odontological Society of Great Britain, January, 188-i-April, 1885. 362 OPERATIVE DENTISTRY. Otaria jubata in the possession of Mr. Bartlett, in which the skull and the jaws are affected with a peculiar porous, soft hyperostosis, similar to that seen in the skulls of rachitic animals at about the period of puberty. He also refers to having found in a raccoon-like dog evident characteristics of moUities ossiiim, and in which the teeth had undergone erosion. He there- fore comes to the conclusion that, from these instances of erosion, associated with constitutional bone disease, and with comparatively functionless, im- perfectly developed teeth, there must be some connection between erosion and defective development. He says further, in reference to the process of absorption which some- times attacks the functionless tusks of the female Indian elephant, "Pathologists have long been aware that morbid changes are more prone to attack undeveloped functionless or imperfectly acting organs ', hence I imagine that the tusks of female elephants are more prone to inflammation than the fully developed representatives in the male." Magitot regarded the disease as a result of caries which has been spon- taneously cvired or arrested by the obliteration (filling up) of the dental tubuli. It is difficult to understand how this author, for whom the writer has the greatest respect, can arrive at such a conclusion from the phenomena presented by the disease. If, as he suggests, it is caries in the incipient stage, arrested by or cured by the obliteration of the tubuli from a deposi- tion of calcareous matter, why is it that in almost every case the teeth thus affected are sensitive, sometimes exquisitely so, to the touch of an instru- ment, changes of temperature, acid condiments, and confections ? Calcified nerve-tissue has no sensation (assuming that nerve-fibrils penetrate the tubuli of the dentin) ; hence his theory in this respect must be erroneous. These cases are also usually progressive, many times extending over a series of years, and perceptible changes can be noted from time to time. Tomes calls attention to another form of the affection in which the loss of substance is not merely confined to isolated spots or surfaces, but in which the whole exposed portion of the tooth is attacked. "As the morbid action goes on the enamel is slowly removed from the crown, so that the teeth become shorter and thinner and assume a peculiar yellowish, trans- lucent appearance, the position of the pulp being strongly marked by the difference in color. In the only case which has come under my own obser- vation, the wasting of the teeth was established beyond all doubt by taking models from time to time. The patient, an anaemic girl, was reduced to a state of great prostration by acute dyspepsia, and was for a considerable time confined to her bed ; she was, however, so hysterical that it was ex- ceedingly difficult to rightly estimate her condition. At one time thei^e was great tenderness of her teeth and general periostitis in the front of the mouth, which, judging by color alone, appears to have resulted in the death of one of the upper central incisors. The use of alkaline applications seemed to have no effect whatever, but the patient's condition has now greatly improved, and the disease appears to be no longer progressing. It is remarkable that during her prolonged illness, while the teeth were being rax)idly eroded, no caries occurred in the mouth." DENUDATION OR EROSION OF THE TEETH. 363 The writer has reported a case* of a somewhat similar character occur- ring in a gentleman of leisure about forty-five years of age, in which the six anterior teeth and the right first bicuspid of the upper jaw are quite extensively denuded, the enamel being entirely removed from all of the teeth named upon their anterior surfaces, with a considerable portion of the dentin, leaving an inclined plane pointing backward, and extending from the margin of the gums to the ends of the teeth, shortening the anterior teeth to the extent of about a sixteenth of an inch. The denuded surfaces were not all grooved in one direction ; the central incisors and the left lateral were grooved horizontally like the others, but were also grooved longitudinally at the cutting edges. The first and second bicuspids of the lower jaw on the right side were also affected, but not to the same extent as those of the upper jaw. Fifteen years before. Dr. Allport, of Chicago, filled with gold the six anterior teeth upon their cutting edges, for the front teeth originally occluded squarely, and by mechanical abrasion cup-shaped cavities had been worn into the dentin, making it necessary to fill them. The centrals were also slightly decayed at the margin of the gums, and small fillings were also inserted there. Six years afterwards it was first observed that the disease had attacked the teeth ; two years later it had progressed so far as to make the edges of the fillings stand out above the surrounding tissue on the labial surfaces. These edges were rounded off and the case dismissed for the time being. Shortly afterwards the gentleman went to Europe and remained there four years. On his return not a vestige of the fillings was left, nor even a de- pression to indicate where they had been, the surface being as smooth and regular as though cut and polished with file or disk. There had also been a i^ercei^tible loss of structure during the past three years, but the destruction had been much less rapid than previously. Numerous other cases might be mentioned to substantiate this posi- tion, as well as the fact that it does not originate in incipient caries. Cases have occurred in their incipiency and progressed stage by stage under our eyes, and at no time have they shown any signs of decay. In the case just mentioned two of the teeth were slightly decayed at the gum line, but none of the others were at any time affected in this way. Underwood f reported a case ' ' occurring in a lady of middle age, who became the subject of erosion after a severe attack of rheumatic gout ac- companied by great depression and mental shock of a severe character. She had never worn an artificial denture. All of the surfaces of the teeth were impartially attacked, so that one bicuspid was reduced to a cube of dentin minus the-eaamel on all sides, while others presented polished grooves traversing their surfaces in all directions, contrary to the usual form in which the loss of substance is limited to the crevices of the teeth. True caries was also present in the mouth ; the reaction of the saliva was strongly acid even just after a meal. Two sisters and a niece of the patient * Transactions of the American Medical Association, 1884. t Aids to Dental Surgery. 364 OPERATIVE DENTISTRY. were free from the affection. One of the sisters, however, had at a later period shown signs of the disease." The late Dr. Eleazer Parmley, of ^STew York, reported some years ago a case in which erosion attacked natural teeth that had been set upon an artificial piece in precisely the same manner as in teeth having natural attachments to the alveolus. J. Tomes and Harris are both inclined to think the disease is one of chemical origin. Tomes suggests that it is caused by the fluid secreted by the mucous membrane covering the parts affected, undergoing fermenta- tion, or affording a nidus for fermentation, and thus may provide an acid solvent. Harris adopts the opinion that the loss of substance which characterizes the affection is produced by the action of acidulated buccal mucus. In every other part of the mouth this fluid is mixed with saliva, and the acid it contains is so diluted as to prevent it from acting on other portions of the teeth. The view held by these authors is the one most generally accepted, perhaps because no better theory has been advanced. This theory, how- ever, does not account for all the j)eculiarities of the disease. To illus- trate : certain teeth are affected in individual cases to the exclusion of others. The writer has had several cases where the disease attacked the superior incisors and bicuspids, while the canines were entirely free, and vice versa, and one marked case of the disease in the lower bicuspids on both sides, while all the other teeth of the mouth escaped entirely. The writer has frequently tested these cases with litmus-paper to ascer- tain the condition of the mucous secretions of the lips and cheeks, but has never found any very marked acid reaction ; in fact, has often foand greater reaction in mouths where the teeth were entirely free from the disease. For several years two brothers who were manufacturers of sulphuric acid were under the professional care of the writer. One of them had charge of the stills, and the other of the chemic laboratory. The former was for hours at a time in a room the atmosphere of which would be highly charged with the fumes of the sulphuric acid, making it necessary to wear a wet sponge over the nose and mouth to protect the air-passages from its irritating effects. The latter was also subjected to the fumes of the acid, but to a much less extent than his brother. Both of these gentle- men suffered very greatly from dental caries during the years that they occupied these positions, but when they gave up this part of the work there was a marked decrease in the amount and progress of the caries. In the brother who spent so much time in the distillery room a con- dition similar to erosion occurred upon the labial surfaces of the ten anterior teeth of both jaws, but upon leaving this work to be done by others the progress of the disease was permanently arrested, as shown by the fact that there has been no further progress for the past ten years. In an article translated from the German by C. E. Koch, and published in the Missouri Dental Journal, August, 1872, the author advances the theory that the disease is one having a close analogy to the process of resorption, attacking the roots of the deciduous teeth prior to their being DENUDATION OR EROSION OF THE TEETH. 365 replaced by the permanent organs. He claims that '• the gum may secrete a fluid endowed with functions similar to those possessed by the absorbent organ found at the roots of the deciduous teeth, and by this means the tissues are removed, leaving the surfaces, as iu the case of the roots of the teeth just mentioned, smooth and polished ;" but qualified his statement by saying that he '^ feels inclined to assume at least a predisposition of the tooth concerned, for the reason that in all cases only certain teeth are attacked by it." He bases his argument, however, upon what he assumes to be a fact,— viz., "that denudation always appears upon the neck of the tooth." He has evidently overlooked the fact that cases of the disease occur, as we have already stated, upon the labial and buccal surfaces, remote from the margin of the gums, at points not likely to be reached by the eroding fluid in sufficient strength to account for the rapid progress of the disease in some of these cases. Tig. 479. Fig. 480. ^«JU Ui iU Teeth where the graiie-oiire has been taken. (After Dr. Darby.) Case attributed to the use of acid phosphate. (After Dr. Darby.) Fig. 479 represents a case of this character reported by Dr. E. T. Darby, in which the affection developed while the patient was taking the grape-cure, and another case, illustrated in Fig. 480, in which the loss of tissue is at the cervices of the teeth, was ascribed to the use of acid phos- phate. Taft is of the opinion that an acidulated buccal mucus is the essential factor in producing erosion, and thinks that constitutional treatment may have a controlling effect ujDon the disease. Charles E. Tomes is inclined to the belief that mechanic abrasion does not fully account for the disease, and that some other factor must play an important part in the process. Truman has long maintained that the disease was caused by an acid fer- mentation taking place in the mouth, more especially at night or when the mouth was in repose, and in corroboration of this theory proved by tests with litmus that the secretions of the mouth almost iuvariablj' gave an acid reaction upon rising in the morning and after a fast of several hours' duration. Kirk believes erosion to be produced by the solvent action of the product of the buccal mucous glands. Garretson was of the opinion that the true exj)lauatiou of the cause of this disease was that enunciated in the experiments of Mr. Kincely Bridgman, the author of the electrochemical theory of decay, and he 366 OPERATIVE DENTISTRY. says, ''My present convictions have led me to believe that in this direc- tion will be found to lie not only the cause of the disease Imt the pro- phylaxis." He furtlier says, "It would seem, however, that back of the immediately acting cause must be a predisposition ; here it would seem to be the result of impressions made on the enamel at the period of its forma- tion, and which deficiency the nutritive functions have failed to correct. It might, indeed, very well be that such enamel is entirely deficient in vital resistance, and thus subject to be acted upon as any inorganic struc- ture, being by electrolytic action simply dissolved." Black * has produced a condition by artificial means out of the mouth which closely resembles erosion. In one experiment which he records two freshly extracted and sound bicuspid teeth were placed with their proximal surfaces together and their roots enveloped in gutta-percha, so that their crowns only were exposed. These were then placed in a glass jar containing a dilute solution of hydrochloric acid (one to four hundred), and by means of a revolving glass paddle-wheel, run by a clock-like mechanism and making forty revolutions per minute, a current was made to impinge upon their outer surfaces, the current striking one with greater force than the other. The result at the end of five days was the disappearance of the cusps and the formation of a groove be- tween the teeth. This groove was most marked upon the tooth which received the greatest force of the current. These exi3eriments were re- peated a number of times with slightly varying results. Stronger solu- tions i^roduced general soften- ing, while solutions of the strength of one of acid to fifteen hundred of water, after a three months' trial, gave no appre- ciable results. Dr. Black, how- ever, does not look upon these experiments as proving any- thing as to the etiology of the disease. He says, however, ' ' the theory that it is caused by acid mucus is suj^ported by several who have written on the subject, and our present knowl- edge affords no alternative but the acceptance of the general idea that it is the action of an acid under some peculiar modi- fying influence as yet unknown to us." Darby maintains that many cases of erosion are associated with the gouty diathesis, and believes that this constitutional condition is an im- portant factor in the causation of the disease. The accompanying illus- FiG. 481. Case where there was gouty relation. (After Dr. Darby.) Fig. 482. Case where there v.-ag gouty relation. (After Dr. Darby.) American System of Dental Surgery, vol. i. p. 1004. DENUDATION OR EROSION OF THE TEETH. 367 trations (Figs. 481 and 482) repi-esent cases that were associated willi tlie gouty diathesis. The writer has frequently noticed that the teeth most often attacked by denudation or erosion are those that are generally classed as medium or soft teeth, or are low in vital resistance, the patient often inheriting a peculiar cachexia, the scrofulous or syphilitic, which has had a depressing influeuce upon the developmental j^rocess, thus lowering the power of vital resist- ance and predisposing the teeth, as well as other organs of the body, to the ravages of disease. There is no doubt that the structure of the teeth is often affected by certain diseases. The marks which they leave on particular portions of the tissue tell at what time the injuiy was wrought and indicate the cause of the disturbance. Syphilis, small-pox, whooping-cough, scarlet fever, and the jDustular diseases leave characteristic marks by which it can be told at what portion of the developmental i)eriod their influence was felt. A peculiar form of the disease is that in whicli the loss of the substance of the teeth is confined to the morsal edges of the anterior teeth. Harris * relates a case of this character in which, during the course of two years, a sex)aration was formed between the ends of the incisors of three-eighths of an inch. Bell has also described a similar case affecting mainly the morsal edges of the incisors and cuspids, which could not be brought into contact with each other. The opening formed between the ends of the teeth was ellij)- tical in shape. This form of the disease cannot by any possibility be attributed to mechanical abrasion or attrition. By some it has been thought to be caused by an acid mucus secreted by the glandular structures of the surface of the tii^ of the tongue, which lying in contact with the lingual surfaces of the anterior teeth at the morsal edges — except during speech or mastication — would keep the solvent fluid in almost constant contact with these surfaces. Pathology. — -Underwood found in the examination of sections of enamel at the seat of erosion that the tissue was structurally defective, having an exaggerated granular appearance. Sections of dentin showed simply the abrupt ending of the fibrils and tubules as if cut with a sharp instrument. An interesting fact was also discovered, — viz., that stained as carefully as possible the substance adjacent to the eroded surface does not take the stain, a condition that might be expected if really due to the action of an acid solvent. Black says, ^'N"either the dentin nor the enamel immediately adjacent to the portions being removed, even uj) to the immediate surface, shows any changes whatever, except it be a slight discoloration which is present in only a portion of the cases." The writer has observed that when discoloration became permanent upon an eroded surface caries soon attacked this surface. The disease in some cases api^ears to be self-limiting, while in others it is progressive. Treatment. — Tlie treatment of denudation or erosion is very unsatis- * Dental Surgery, p. 264. 368 OPERATIVE DENTISTRY. factory, for no remedy has yet been discovered whicli will arrest the progress of the disease. Certain remedies are sometimes applied in an em- pirical sort of way, with the view of checking the progress of the disease, like alkaline mouth- washes, antiseptic solutions, and alcohol, and the dis- continuance of the use of tooth-powders and stiff tooth-brushes. To relieve the extreme hypersensitive condition of the dentinal fibrillse the eroded surfaces may be touched with zinc chloride, or if the surface is not exposed to view, it may be touched with silver nitrate. In the more advanced stages of the disease the cavity thus formed may be properly shaped and filled with gold. This operation in many cases does not seem to arrest or even check the progress of the disease, for it is the experience of most operators that in from three to six years these fillings will be lost by reason of the disease progressing until the sup- ports of the filling were dissolved away. Tlie writer has found that in a certain few cases zinc oxyphosphate cement seemed to exert a controlling effect upon the disease, and in these cases the cement fillings lasted exceptionally long. Whether this was due to some peculiar action of the cement, to a chance association of a changed condition in the oral fluids, or to a natural limitation of the disease, it would be very difficult to decide. One marked effect of protecting the eroded surfaces with zinc oxyphosphate was the abatement, after a few weeks, of the extreme hypersensitiveness. ATTRITION OR ABRASION. Definition. — Attrition (Latin, atterere, to rub against), any rubbing or friction which wears a surface. Applied to the teeth, it is the wearing away of the tooth -substance, caused by the friction of mastication . Abrasion (Latin, abrasio ; ab, priv., radere, to rub), in dentistry, the wearing away of the enamel and dentin ui)on the morsal surfaces by mechanical means, or a loss of substance through friction of a foreign body. Mechanical attrition of the teeth is a common condition in individuals past middle life and in the deciduous teeth of children. The morsal sur- faces of the bicuspids and molars are most often the seat of this loss of substance, but when the occlusion of the teeth is such that the six anterior teeth impinge squarely upon each other, the morsal edges of the incisors and the cusps of the cuspids also become worn away, forming broad surfaces, which has given rise to the notion among some of the less intelligent laity that some people "have double teeth all around." As the process of attri- tion goes on the teeth become shorter and shorter until in some cases they are actually worn down to the gums. Some animals, notably the rodents, have teeth which grow continually, so that the wear which takes place from the severe use to which they are subjected is counterbalanced by their continuous growth. Not so with man, for with his teeth when once fully developed there is no compensation for wear or injury. Unlike other organs and tissues of his body, they are incapable of repairing losses which may be sustained by disease, injury, or wear. A certain amount of wear always takes place upon the morsal surfaces and edges of the teeth from childhood to old age ; this would be termed normal attrition. DENUDATION OR EROSION OF THE TEETH. 369 On the other hand, the wear which takes place in some cases is entirely- abnormal. Causes.— The amount of attrition which may take place in any indi- vidual case will depend very largely upon the character of the food, the density of the tooth-structure, the form of the occlusion, and the habits. It may attack the morsal surfaces of all of the teeth, or it may affect only one or two teeth. When tlie anterior teeth occlude squarely together all of the teeth will be worn by attrition. When the occlusion is normal only the bicuspids and the molars will be affected, but when the attrition is localized it will be due to malposition or irregularity of one or more teeth, or to some peculiar habit, like holding a pipe between the teeth always in the same location. The character of the food plays an important part in the normal wear or attrition of the teeth. Foods which are hard and require considerable mastication or grinding to reduce them to a proper state to enter the stomach cause more surface wear of the teeth than foods which are soft. This is particularly noticeable in the museum collection of skulls of abo- riginal x)eoples whose food was coarse and contained much giitty material intermixed with it, as a result of their primitive method of grinding their cereals. The same conditions are noticeable in the negro of the South, and in sailors and soldiers who have been in service for long terms, and whose food has been of necessity composed of coarse and hard materials. Predisposing Causes. — It has been thought by some authorities that the difference in the density of tooth-structure was an imi^ortant predis- posing factor in the attrition of the teeth. Confidence in the importance of this theory as a causative factor in the wearing away of the teeth has been somewhat severely shaken by the publication of the results of Dr. Black's experimental research into the question of the differences of density in the teeth of individuals from youth to old age. He found, as already re- ferred to in another part of this work, that the differences were so slight as to be of no importance as a controlling influence in the predisposition to caries, and these conclusions are equally aj^plicable to the pi-edisposition of the teeth to be worn away by attrition. The most important predisposing cause of mechanical attrition is an abnormal occlusion of the teeth. When the teeth of the opposing jaws form a normal occlusion, the cusps of the bicuspids and molars interlock- ing with each other, the buccal cusps of the superior teeth shutting over the buccal cusps of the inferior teeth, and the superior incisors and cuspids shutting over those of the lower jaw, the surface wear or attrition will occur in the bicuspids and molars upon the sides of the cusjis which come into antagonism, and thus the grinding and triturating character of these teeth will be maintained to the end of life ; while the incisive and tearing character of the anterior teeth will be maintained by the same normal process or wear. If, on the other hand, the occlusion of the teeth is such that the points of the cusps of the posterior teeth and the morsal edges of the incisors and cuspids only come in contact, a sliding motion of the teeth of one jaw upon those of the other becomes necessary in triturating and grinding the food. 24 870 OPERATIVE DENTISTRY. In time the cusps of the teetli are completely worn away, and the morsal or incisive edge of the anterior teeth is destroyed, thus reducing the mor- sal surfaces to flat planes. As soon as the enamel upon these surfaces is lost at any one point, the dentin wears away so much more rapidly than the remaining enamel that cup shaped depressions are formed in the dentin, which grow deeper and deeper until they become an annoyance either from their extreme sensitivenesss or from the retention of food debris. The malocclusion of one or more teeth often causes a localized attrition, as, for instance, when a lateral incisor or a bicuspid is so malposed as to throw it out of the normal alignment of the dental arch, thereby causing it to interlock with the ox^posing tooth in such a manner as to produce excessive attrition upon the labial or lingual surfaces of these teeth. Another cause of abnormal attrition is the loss of several teeth upon one or both sides of the jaw, thus throwing extra work upou the remain- ing teeth. The most common condition of this character is where the posterior teeth have been lost, and the whole labor of triturating and grinding the food is thrown upon the anterior teeth. Habit is also an imjDortant factor in the attrition of the teeth. This is noticed in certain individuals who when the mind is engaged are con- stantly grinding their teeth together, or who, by canying the jaw forward or laterally, bring two teeth together, and by a constant rubbing motion wear away the prominent points of these teeth. ■ The habit once formed usually remains, and thus an abnormal attrition of the teeth involved is produced. Pathology. — Smale and Colyer* claim that attrition is always most marked in those individuals who are of a gouty diathesis. The only changes observable in the structures of the dental tissues are the abrupt ending of the dentinal tubules at the worn surface, the evident consolidation of the fibrillse in certain cases, the deposition of secondary dentin in the pulp-chamber nearest to the point of surface wear, and atrophic changes in the pulp itself. Treatment. — In many of these cases treatment is not required. In those in which cavities or depressions have been worn in the surfaces of the teeth a retentive shape should be given to them and the cavities filled with gold. In those in which the pulj) has been dangerously ax)i:>roached gold crowns may be inserted and the normal sej)aration of the jaws re- stored, porcelain facings or porcelain crowns being used in all locations in which the artistic sense would be offended by the exhibition of glitter- ing gold crowns. When the posterior teeth have been lost and the anterior teeth are being rajiidly worn down, artificial dentures should be inserted and the " bite" lengthened so as to relieve the wear upon the anterior teeth. "When the insertion of artificial dentures will not be permitted, the ends of the anterior teeth may be protected by the insertion of gold fillings which cover the edges of the enamel and lengthen the " bite," as described in a preceding part of this work. •^ Diseases and Injuries of the TeetL, \). 282. DENUDATION OR EROSION OF THE TEETH. 371 Abrasion.— By the use of the term abrasion the writer means that loss of tooth-substance which is caused by the friction of foreign bodies as for instance, artificial dentures made upon a metal base or retained in the mouth by metal clasps which surround certain teeth ; the undue applica- tion of the tooth-brush and of dentifrices ; the use of the clay pipe, and of chewing tobacco and the betel-nut. The most common cause of abrasion is the friction of metal plates and clasps. This condition is most likely to occur when the plate or the clasp does not properly fit, thus permitting constant motion during speech and mastication. These losses of substance are always at those points upon the teeth where the friction has been applied. Such abraided surfaces often become exquisitely sensitive and call for treatment. When these abrasions occur in locations not readily kept clean caries is liable to supervene. Abrasions from the use of the tooth-brush and dentifrices are exceedingly rare. A few such cases will, however, present in the practice of nearly every dentist, but they appear so seldom that they are usually encountered as a surprise. Individuals who have this form of abrasion are those who are so scrupulously neat about the care of their mouths that for fear they will not keep their teeth clean they employ the stiflest brushes that can be found, and often add pulverized pumice-stone to their dentifrices to be sure that all stains and deposits are prevented from accumulating upon them. These abrasions are usu- ally found upon the labial and Fig. 483. buccal surfaces of the teeth, and might be readily mistaken for denudation or erosion (Fig. 483). Abrasions from the use of the clay pipe are most frequently seen among the x)eoj)le of the lower walks of life, particularly "" -, ^ T • , -1 Case showing abrasion by tooth-brush. (After among laborers having out-door Dr s b Palmer ) occupations, who smoke a great deal, and hold the pipe gripped between the teeth while at work. The stem of the pipe is usually held in the same place, and after a time the teeth become worn at this x^oint to such an extent that they do not occlude, and an ojDen space the form of the pipe-stem remains when the other teeth are in contact. The writer once saw an elderly Irishwoman who was a constant user of the clay pipe, in whom the groove formed between the opjDOsing teeth at the angle of the mouth was so deep and large that she had been of late years obliged to wind the stem of her pipe with a strip of linen to make it large enough to be gri]:)ped by the worn teeth. Abrasion from chewing tobacco is quite common among old sailors and the negroes in the tobacco-raising districts of the South, while among the native low-caste Hindoos and Burmese, who mix lime with their betel-nut to form a pungent •'quid,-' abrasion is verj- common. Tobacco and betel- nut chewers, as a rule, always chew the quid upon the same side of the mouth, and as a consequence the abrasion always occurs upon that side. The constant friction of the tobacco — which always contains more or less 372 OPERATIVE DENTISTRY. grit, particularly so when the unprejiared leaf is used, as by the negroes of the South — and of the betel-nut mixed with lime rapidly wears away the morsal surfaces of the teeth employed in masticating the quid. The writer has seen several cases in which the teeth had been worn to such an extent by this process that they did not meet by a fourth of an inch. The treatment of an abrasion is the same as that employed in erosion and attrition. CHAPTEE XXIIL DISEASES AND INJURIES OF THE DENTAL PULP AND THEIE TREATMENT. In a preceding chapter the various stages of caries were described, and in the following chapters the treatment of the superficial, progressive, and deep-seated stages have been discussed. It now remains to take up the last or complicated stage of the disease ; that stage in which the carious process has penetrated so deeply into the dentin that it may have nearly or quite exposed the pulp and produced irritation and pain in this organ, and possibly jeopardized its vitality. The pathology of the dental pulp has been most completely studied by "Wedl, Salter, and Black, and nearly all of the knowledge now possessed upon this most interesting and important topic has come to us as a result of their researches. The subject, however, still remains a fruitful field for further investigation, for many problems are still unsolved and many questions need further elucidation. The pathologic changes in the pulp which have been most carefully studied and described are those in connection with hyperaemia, inflamma- tion, secondary deposits, calcareous and fatty degenerations. HYPEREMIA OF THE DENTAL PULP. Definition. — Hypersemia (Greek, uitip^ over; al/xa^ blood), a condition of plethora or congestion. Hypersemia of the dental pulp is a condition in which the vessels of the pulp are dilated and excessively filled with blood. Hypersemia may be considered as the most important pathologic condi- tion to which the pulp is subject, for the reason that it is a common affec- tion and often terminates in the destruction of the organ. Hypersemia may be transient or persistent, its character dejjending upon the nature, degree, and duration of the irritation which induces it. Irritation is the state of a tissue or an organ in which there is an excess in vital movement, commonly manifested by increase of the circulation and of the sensitivity. Irritation in some form always precedes hypersemia and inflammation ; or, in other words, these conditions are always caused by some form of irritation. When the irritation is confined to a particular portion of the body it is termed local irritation. When it affects the whole system it is termed gcTieral or constitutional irritation. Hyperaemia is there- fore an expression of a state of irritation which may be either local or general. Hypersemia, however, may be a physiologic or a pathologic condition. Flushing of the cheeks as a result of mental excitement produced by joy, shame, or anger is an illustration of a physiologic hypersemia ; while the redness following a local irritation would more nearly express a pathologic hypersemia. ^^ 373 374 OPERATIVE PENTISTRY, Transient hypercmiia may be induced as an accidental condition in sound teeth by thermal shock, by diminution of atmospheric pressure, such as is experienced in high altitudes, or by injuries which are not of a serious na- ture but sufficient to produce a congested condition of the pericemental membrane and, by association therewith, transient hypersemia of the pulj). This condition rarely produces more than a mild and fleeting sensation of pain, but yet is a sufficient reminder of what might ensue if the irrita- tion were long continued, and to warn the individual not to unnecessarily expose himself to its influence. Persistent liypercemia of the pulp is of two forms, — active or arterial and •passive or venous. Active hpyercemia is a condition in which the arteries and capillaries of the pulp are excessively filled with blood, and, as a result, abnormally dilated. Passive hypercemia, or venous hypersemia of the pulp, is a condition in which the veins and venules suffer engorgement by reason of compression at the apical extremity of the pulp-canal. This condition is indiiced by irritation and a consequent increased flow of blood through the arteries, followed by their dilatation and the immigration of the leucocytes. Thus the arteries occupy more than their normal space in the canal, while the leucocytes fill the meshes of the connective tissue and thus produce com- pression upon the veins or vessels of exit. The susceptibility of the pulp to external irritation varies greatly in different individuals, while age, temperament, and diathesis play an im- portant part. Susceptibility to irritation is much greater in youth than in adult life, and in persons of high-strung nervous temperament than in the phlegmatic. Persons of a tuberculous or syphilitic diathesis are very susceptible to all forms of irritation and prone to degenerative tissue changes. Irritation, on the other hand, is well known to be a prolific cause of new formations, provided the irritation is not too intense in character. Slight irritations, if of a continuous character, often result in hyperplasias of tissue, as, for instance, in the increased develojiment of cement-tissue at the apices of the roots of teeth which have been subjected to the irritation of malocclusion, the strain of carrying a i)late which has been clasped to them, or of supporting a bridge ; while if the irritation is excessive it is liable to produce resorption or other destructive pathologic changes. This is often seen in the roots of devitalized teeth which are in a septic condi- tion or are the seat of chronic abscess. Again, it is a well-known fact that owing to slight irritations of the dental pulp from such causes as produce a slow and gradual loss of the hard struc- tures of the teeth, like the abrasions of mastication or of metal clasj)S or the erosion of the enamel at the cervical margins or upon the labial surfaces of the anterior teeth, or from slowly progressing caries, secondary deposits are formed in th.e pulp-chamber opposite the point of irritation, and pro- ceed synchronously with the destruction of the external tissues until the eiitire coronal portion of the pulp-chamber is filled and the crowns DISEASES AND INJURIES OF THE DENTAL PULP. 375 of the teeth are worn down to the gum. If, however, the process of de- struction is rapid the pulp is soon exposed, and hypersemia and inflamma- tion supervene, thus putting an end to all chances of protecting the pulp by new formations, as such growths are never formed when acute inflam- matory symptoms are present. Causes.— Hyperaemia of the pulp may be induced by many and varied forms of irritation, both local and constitutional. Local Causes of Irritation. — These may be divided into external^ or those which operate from without, and internal, or those which operate from within, the pulp. External Local Causes. — Caries in its various stages ; traumatic injuries ; abrasions ; erosions ; chemic reactions from sweets, acids, etc. ; excessive thermic changes ; instrumentation ; mechanic irritation from metallic fill- ings ; incompatibility of fillings ; pressure from fillings and other foreign substances upon the thinned walls of the pulp-chamber ; galvanic shock ; septic infection. Internal Local Causes. — Dentinal tumors ; pulp-nodules. Constitutional Causes. — Xervous irritability ; plethora ; pregnancy. Hypermmia from External Causes. — Caries in the deep-seated stage is the most common of all the causes of irritation which produce or excite a determination of blood to the pulp, resulting in hyperaemia. Acute hyijersemia may occur from caries in any of its stages, but most frequently when the disease has progressed so far as to nearly expose the pulp, or it has been nearly uncovered by a traumatic injury or by abrasion or erosion. External irritants, like thermal shock and chemic reactions, are usually the exciting causes of hyperaemia. There are, nevertheless, certain individuals in whom general nervous irritability and local hyperesthesia may be so greatly exalted at times that trivial forms of irritation become unbearable. Under such circumstances hyperaemia of the pulp may be induced by the most Superficial cavities of decay, particularly when they are located at the cervix of the tooth. In such persons the introduction of metal fillings, even in the most shallow cavities, are frequently jDroductive of a persistent active hyperaemia and severe odontalgia, necessitating the removal of the filling before relief can be obtained, while if the filling is permitted to remain inflammationof the pulp supervenes. Irritability of this character results sooner or later, according to the intensity of the hyperaemia pro- duced, in either death of the pulp, the formation of secondary deposits in the form of dentinal tumors, or pulp nodules, or in a general fatty or calcareous degeneration. On the other hand, secondary formations or deposits are not infre- quently found within the pulp-tissue, which can in no wise be accounted for as resulting from external agencies, and which are sometimes productive of a most persistent form of irritation, accompanied by severe neuralgic pains, while at other times the irritation may assume a low chronic form, resulting in various obscure reflex symptoms. Chemic reactions from sweets, acids, salt, etc., taken into the mouth as food or condiments, when coming in contact with the exposed dentin of vital teeth, may, even in the case of superficial caries, in the recession of the gums 376 OPERATIVE DENTISTRY. which exposes tlie cervices of the teeth, in chemic erosion and mechanic abrasions, produce a persistent hyperaemia of the pulp, the nature of which is determined by the severity and duration of the irritation, the excita- bility of the dentinal fibrillse, and the general nervous irritability of the individual. Excessive thermic changes and chemic reaction, operating upon the ex- posed or carious dentin of vital teeth, are the most frequent exciting causes of hyperaerriia of the pulp. The thermic or heat sense of individual teeth is often augmented by the action of caries, or by other processes or injuries which denude the dentin of its natural protecting covering, so that tem- peratures which had been readily tolerated when the tooth was in a normal state become under these abnormal conditions painful or absolutely in- tolerable ; while, upon the other hand, in neurasthenic individuals, certain sound teeth, and sometimes, though rarely, all of the teeth, become hyper- sensitive, so that the pressure of mastication is no longer borne with com- fort, and contact with foreign substances occurring at the cervices of the teeth or at points unprotected by the enamel is exceedingly painful, but in which the degree of pressure exerted or the form of contact does not seem to hold any relation to the amount or the character of the pain induced. The same is true of thermic changes ; the differences in the degree of heat and cold beyond the point of toleration do not seem to make any especial difference in the intensity of the pain. In the former condition hypersemia may be induced as a consequence of irritation, and the pulp, if examined at the time, will be found to be passing into a state of disorganization ; while in the latter, if the offending tooth is extracted, macroscopic and microscopic examination may fail to discover any structural changes what- ever in the pulp or the calcified tissues of the tooth. Instrumentation, such as is employed in the excavation of a hypersensi- tive cavity of decay, is often very painful, and the irritation induced by the i)rocess will, in certain individuals of exalted nervous irritability, pro- duce an active hyperaemia of the pulp. A common form of irritative instrumentation, and one which more often results in producing active hypersemia, is that caused by the friction of rapidly revolving engine burs and disks, which are permitted to heat the tooth beyond the limit of nor- mal toleration. The friction induced by the rapidly revolving bur may be prevented by causing a stream of tepid water to flow over it from a syringe, while the friction and consequent heating of the tooth iji finishing a filling with sand-paper and cuttle-fish disks may be greatly lessened by lubricating the surface with toilet soap or vaseline. Incompatibility of metal fillings with the structures of the teeth is often productive of serious annoyance from the irritation produced by the pres- ence of the foreign body in the hard structures of the tooth, for such it must be considered under these circumstances. Hypereemia of the pulp which is induced by the presence of metallic fillings in the tooth is due, as already intimated, to a peculiar and exalted general nervous susceptibility of the individual to various forms of irrita- tion, and to an excessive excitability or irritability of the dentinal fibrillje, which makes them intolerant of all foreign substances used as filling- DISEASES AND INJURIES OF THE DENTAL PULP. 377 materials, wliicli are very far removed from the dentin in their power to carry caloric impressions and electric currents. This is proved by the fact that such teeth which have been filled with metals are soon made entirely comfortable by the removal of the metallic fillings and substituting gutta- percha or porcelain inlays. Pressure of fillings is sometimes a cause of irritation of the pulp, and is rapidly followed by acute or active hyperaemia. Pressure sufficient to cause Irritation can only occur in those cases in which the layer of dentin covei'ing the pulp is vqvj thin, or so considerably decalcified as to cause it to bend under the stress of the force used in packing the filling into the cavity. Hypertemia which is caused by this form of irritation rapidly pro- gresses to congestion and partial stasis, accompanied by excruciating throb- bing pain, and later ending in strangulation of the apical vessels and death of the pulp, unless the filling is immediately removed and the irritation allayed hy local applications to the pulp of soothing or anodyne drugs, like the tincture of opium, morphine, or cocaine. If, however, continuous pain has been present for more than two or three days, conservative treatment of the pulp will usually prove unavail- ing for the reason that the irritation has been so violent as to completely overcome the resistive powers of the pulp and render recuperation nearly, if not quite, impossible. Devitalization then becomes the only means of giving comfort to the patient and preserving the tooth. Galvanic shocJc is another and not infrequent cause of irritation and hypersemia of the pulp. This form of irritation is produced in the mouth by the contact of dissimilar metals, the surfaces of which are bathed with saliva having a slightly acid reaction, as, for instance, the contact of gold and amalgam fillings in occluding teeth, or in the approximating surfaces of teeth which are not in close contact, but which by the occasional suspen- sion of food debris or the oral secretions make and break the circuit during the acts of mastication, speech, deglutition, or in other movements of the jaws, tongue, and the muscles of mastication. Metal iDlates occasionally pro- duce the same effects when in contact with fillings of a different potential. Fillings composed of metals of a different potential placed in the same cavity do not — even when moisture can penetrate between them — produce galvanic shock, for the reason that the galvanic current established be- tween them is continuous, and without the presence of moisture it would be very slight indeed, except upon the exposed surfaces, and this soon ceases from the gradual oxidation of the surface of the baser metal, ^¥hen gold and amalgam are placed in the morsal surface of the same tooth, but in cavities separated by a more or less thin wall of dental tissue, painful galvanic shock sometimes occurs during the act of mastication, by the current being completed and broken by the contact of masses of food which are so placed at the time as to form a connection or circuit between the two fillings. Another source of galvanic shock is the contact of a table fork, knife, or spoon with a gold or a bright amalgam filling ; such shock is sometimes very painful. 378 OPEKATIVE DENTISTRY. The character of the hypersemia produced by galvanic shock will depend in large measure upon the intensity and the frequency with which the shocks occur and the susceptibility of the individual to such form of irritation. In the one case it may result in acute hyperaemia and severe attacks of odontalgia, while in another it may develop a pas- sive or chronic hyperaemia with calcareous deposits or other degenerative changes. The treatment of this form of irritation should be, invariably, the removal of one of the offending fillings and replacing it with a metal like the other, or with a material possessing no conducting or electric properties, like gutta-i>ercha or zinc phosphate. Septic infection is often a source of acute hypersBmia of the pulp. This is commonly caused by the invasion of the pulp-chamber by the disin- tegrating processes of caries. It, however not infrequently occurs in those cases in which the pulp has not been exposed, but is still covered with a layer of decalcified and softened dentin (pseudo-exposure), the tubuli of which are filled with saprophytic and pyogenic organisms which readily penetrate to the pulp and establish sej)tic irritation, inflammation, suppuration, and devitalization. A thin layer of sound dentin is a posi- tive external protection against the infection of the pulp with the pyogenic organisms. It is nevertheless possible for suppurative conditions to be established in the pulj) without direct external infection. The presence of j^yogenic organisms in the blood- current which may have gained an entrance through some abrasion of the skin or mucous membrane, or through a wound, or pre-existing abscess, has long been recognized. These are capable when they become arrested in a vessel of rapidly propagating and overcoming the vis naiurce of the surrounding tissues and establishing suppurative con- ditions. This explains the presence of abscesses of the pulp which are occasionally found in perfectly sound teeth, the contents of the pulp- chamber having the appearance of the pus found in cold abscesses, and which, like the cold abscesses found in the bones and soft tissues of tuber- cular individuals, have not and do not present any acute symx)toms until they are opened, when, if the utmost aseptic precautions are not observed, they sometimes take on most violent inflammatory conditions which may, in extreme cases, terminate in the loss of the tooth and in establishing acute septicaemia. Symptoms. — The symptoms of active or acute hyperaemia of the pulj) are sharp, lancinating pains, produced by hot or cold substances coming into contact with a vital tooth which has been partially de- stroyed by caries, traumatic injury, abrasion, or erosion, or which con- tains a metal filling, or by the contact of sweet or acid substances with the denuded surface. So long as the shock of irritation of these agencies produces a quick, sharp, and transient paroxysm of pain, which reap- pears only upon an application of the irritation, it may be safely in- ferred that no serious vascular disturbance is present ; but when the paroxysms of pain are not only sharp and lancinating, but prolonged for several minutes or even hours after contact with these irritating agencies, DISEASES AND INJURIES OF THE DENTAL PULP. 379 it may be suspected that serious disturbances are taking place iu the ves- sels of the pulp. Slight tenderness to percussion or to forcible occlusion is often a sub- jective symptom. This is due, in all probability, to an associated sympa- thetic hypersemia of the pericemental vessels surrounding the apex of the root. The pain, in the absence of active irritation, is usually diffused over the entire side of the jaw and but vaguely located, and may be referred by the patient to an adjoining tooth or to one in the immediate neighborhood. Sometimes the pain is reflected to a tooth upon the same side of the jaw- but remote from the seat of trouble, or it may be reflected to the corre- si)onding tooth or some other in the opposite jaw. Occasionally this symp- tom will assume a neuralgic character, the pain being located in the ear, or it may manifest itself in the ophthalmic division of the fifth nerve and produce lachrymation, hypersemia, or inflammation of the conjunctiva, and even amaurosis. "When the pain is neuralgic in character the "points douloureux" of Valliex are often well marked in the trifacial nerve. In the oplithahnic division these tender points are located at the supraorbital foramen, the upper eyelid at the line of union of the nasal bone witli the cartilage, at the inner angle of the orbit, and in the globe of the eye. Another i)oint is near the i^arietal eminence. In the superior maxillary division the tender j^oints are situated at the infraorbital foramen, at the point over the most prominent part of the malar bone, an uncertain point upon the gum of the superior maxilla, a similar point upon the upper li]3, and another upon the j)alate. In the inferior maxillary division the tender points are found over the auriculo-temporal branch just in front of the ear ; another is located over the inferior dental foramen, and still another over the mental foramen. Diagnosis. — Diagnosis in even the most obscure cases of hyperaemia of the pulp can usually be made by forcing a jet of cold air into the cavity from a chip-blower, or by the application of a jet of cold water having a temperature not lower than 60° F., thrown from a syringe upon the suspected tooth. In the absence of a cavity, fillings should be sought for and tested by the same means. Failing with these, hot water maj^ be used in the same manner. Or the positive pole of the galvanic current may be ap- plied. As a rule, the application of any one of these methods will render the diagnosis sure by immediately stimulating a responsive twinge of pain. More rigorous means will excite a severe paroxysm of pain in the offending tooth and aggravate the neuralgic symptoms. Pathology. — The principal and characteristic pathologic change which takes place in active hyx)eraemia of the pulp is an irregidar dilatation of its Mood-vessels. Salter * (1875) was the first to discover this peculiarity of the vessels of the pulp while studying the pathology of suppurating and sloughing pulps. He describes the condition as an irregular dilatation of the smaller vessels into ampullse filled with clots, and which he believed to be due to engorgement of the vessels, loss of vital contractility, passive yielding of the over-distended and thinned walls, and coagulation of the * Dental Pathology and Surgery. 380 OPERATIVE DENTISTRY. blood. Albrecht*(lS5S) called attention to the notable increase in the volume of the blood vessels and to their tortuous course. Wedl f (1870) Fig. 484. Hypersemia of the dental pulp, showing the natural injection of the vessels, (After Black.) a, a, membrana eboris, orla.ver of odontoblasts; 6, 6, 6, b, vessels distended with blood ; c, c. c. c, points from which the blood has fallen in handling the section. also describes a swollen and lax condition of the fibrous sheaths of the small arteries and veins. Fig. 485. Dilated blood-vessels from the dental pulp in hyperemia, from tooth extracted during a paroxysm of intense pain. (After Black.) Black I (1886) found the dilated and varicosed condition of the vessels of the pulp (Fig. 484) to be so constant as to form a characteristic patho- * Krankheiter der Zahnpulpe. J American System of Dentistry. t Pathology of the Teeth. DISEASES AND INJURIES OF THE DENTAL PULP. 381 logic feature of the acute form of the affection. Fig. 485 was made by Dr. Black from a section of the pulp of a tooth which was extracted during a paroxysm of acute pain. The tooth had been troubling for several weeks, the paroxysms of pain being excited by very trivial changes in tempera- ture and lasting for an hour or more. He also found in other cases of a similar character, but which were extracted during an interval between the paroxysms of pain, that nothing of a remarkable character was pre- sented. The veins of a bulbous portion of the pulp may be abnormally large and engorged with blood, while the arteries will be almost or quite empty and the injection of the capillary system wanting. Black looks upon the increased susceptibility of the pulp to thermal shock as "in a large degree due to nervous phenomena. The tension of the blood-vessels and their degree of contractibility are phenomena which are controlled by the vasomotor system, and in the dental pulp these are prominently affected by thermal changes in such a way that the vessels expand passively before the j^ressure of the circulation," The dilatation of the vessels is due to a paralysis of the vaso-constrictor fibres, and the varicosed condition to an irregular paralysis of these fibres. The effect of painful stimulation or irritation upon the vasomotor system of nerves is to cause an immediate contraction of the vasoconstrictor fibres of the walls of the vessels and narrowing of their lumen ; this is followed by reaction and stimulation of the vasodilator fibres, which cause a dilatation of the lumen of the vessel, and permit a greater quan- tity of blood to flow through it than is normal, which constitutes a transi- tory hypersemia. In persistent hyperemia of a pronounced type the vasoconstrictor fibres suffer paralysis for a time, -resulting in a continued expansion of the vessels, which may become permanent if the irritation is of a continuous character. Black found as a result of his researches that the vessels of the pulp possessed a wonderful degree of recuperative power, and that the vessel walls frequently recover their normal tonicity. In the more advanced stage of arterial hyperjDemia another phenomenon is sometimes presented. This is the escape or migration of the red blood- corpuscles through the walls of the vessels, forming areas of a reddish hue, and in other instances of deeper color, having the appearance of ex- travasations of blood. These are in all probability due to embolism and the formation of an infarct. An infarct is a dark-red, wedge-shaped area in an organ due to the occlusion of a vessel by an embolus, with the sub- sequent extravasation of blood into the tissues beyond the point of obstruc- tion. The base of the wedge is towards the periphery of the organ, and the apex towards the point from which the blood-clot entered the obstructed vessel. Passive or venous hypercemia can only be inferred from the character of its symptoms, which are dull, heavy, gnawing pains, accompanied by a sense of fulness, the intensity of the pain often being steadily maintained for many hours. These symptoms are probably due to the dilatation of the arteries which enter at the -apical foramen, causing pressure upon the veins and pieventing the escape of the blood from the pulp by these chan- 382 OPERATIVE DENTISTRY. nels. In teetli possessing two or more roots, the liypersemia may be some- what lessened by the escape of the blood through the veins of a second root. In single-rooted teeth this cannot occur, and if the congestion ex- tends to the apex of the tooth, the pain will continue until strangulation or general infarction takes place. Prognosis. — Hypersemia from external irritants, if unrelieved, usually leads to diffuse inflammation of the pulp, probably as a result of infarc- tion and the extravasation of the red blood-cori)uscles. Cohnheim's ex- periments seem conclusive that inflammation does not result from even the most extreme hyperiemia that can be induced by the jDaralysis of the vaso- motor nerves. Black * was not able to determine whether diffuse inflam- mation would occur before infarction and extravasation had taken place or not, but was inclined to believe with Cohnheim that it would not. His own observations, however, show conclusively that in every case of ex- travasation a mild form of inflammatory action had been induced, by which new elements were thrown out which acted the part of absorbents in the removal of the extravasated blood, and in this way he believes a general diffuse inflammation of the pulp may be set u]3 as a result of hypersemia. He thinks this will exj)laiu those cases of diffuse inflamma- tion of the pulp which often occur without the exposure of the organ to any of the forms of external irritation. Absorption of the extravasated red blood-corpuscles takes place through the phagocytic action of the leucocytes. The progress of active hypersemia will depend upon the temperament and the general health of the patient, the duration and character of the irritation, the severity and frequency of the paroxysms of i)ain, and the extent to which the crown of the tooth has been destroyed by caries or other causes. The power of the pulp to recover after repeated attacks of hypersemia points strongly to a favorable prognosis in those cases which have escaped infarction and septic infection ; provided the temperament, age, and the general health of the individual do not operate against it. Conservative treatment should therefore be adopted in all cases in which a favorable prognosis may be hoped for. It is not to be expected, however, that every case so treated will prove successful, any more than that one should expect every case in which the pulp is removed to prove successful. A certain number will prove failures in either case, but the percentage of successes and failures will depend (after the individual equation of the patient has been eliminated from the proposition) very largely upon the diagnostic ability and manipulative skill of the operator, coupled with good judgment in the selection of the particular method of treatment to be employed. The writer maintains that inasmuch as the pulp of the fully calcified tooth is its organ of nutrition and sensation, it has two important functions to fulfil, — functions which should be preserved as long as jDOSsible, that the tooth may perform to completion its many ofiices as nature intended ; and * American System of Dentistry. DISEASES AND INJURIES OF THE DENTAL PULP. 383 furthermore, that the pulj:* should uever be ruthlessly destroyed, because, forsooth, it has souuded au alarm ou the too near approach to its citadel of the arch-enemy, dental caries. Many operators look upon all efforts to conserve the vitality of the pulp, after it has given evidence of being the seat of hyperemia, as largely experimental, with the chances of failure very greatly in the ascendency, and for this reason advise devitalization and extirpation as the surest way of rendering the tooth comfortable. Other equally skilful and conscientious operators attempt the con- servation of the pulp even after it has been the seat of hypersemia for several days, and succeed in a good per cent, of cases in preserving their vitality, as pi'oved by their responding to the usual tests many years after- wards. The age and the general health of the patient are important factors in the recuperative powers of the pulp. Conservative treatment of the pulp is much more likely to prove successful in youth and early adult life than in middle life or old age, while in the debilitated or those suffering from tuberculosis or other infectious diseases the prognosis is very unfavorable. Treatment. — The rational treatment of any surgical disease or injury comprehends two general principles : first, the removal of the cause ; and second, rest of the organ or part which should approach complete physiologic rest as nearly as possible. These principles should always be carried out in the treatment of dental diseases, for they can be as readily applied in this class of diseases as they can in the more serious surgical diseases or injuries. In the treatment of hypersemia of the pulj), the first effort should be directed towards giving relief from the pain, and this can best be accom- plished by the removal of the cause of irritation. When the disturbance to the pulp arises through a carious cavity in the tooth, this should be freed from food debris by carefully syringing the cavity with tepid water to which has been added in proper strength a suitable alkali or an anti- septic. Bicarbonate of soda is the best alkali for the purpose, and listerine, pasteurine, borolyjitol, thymolene, and formol are the best of the i)repai'ed antiseptics. The simple removal of the dShris and neutralizing the acid condition of the disorganized dentin will often be all that will be required to give immediate relief from the pain. The next step is to remove the dis- organized dentin, care being taken not to expose the pulp, as an accident of this character complicates the treatment and renders the prognosis of the case somewhat more doubtful. The writer believes with many other practitioners of somewhat ex- tended experience that it is better practice to leave a layer of decalcified dentin over a living but hyperaemic pulj) than to remove this covering and substitute for it a foreign substance, which can by no possible stretch of the imagination be thought to be as compatible to the pulp as the tissue — though partially disorganized — which nature formed for its protection ; and for the further reason that such practice gives better results, in conserving the organ, than does capping with a foreign substance. The cavity should now be dressed with some remedy possessing sedative 384 OPERATIVE DENTISTRY. and antiseptic qiialitiesi; like the oils of cloves, cinnamon, tliyme, gaul- theria, peppermint, etc., applied upon a pledget of cotton and sealed in with temporary stopping or zinc oxyphosphate. Carbolic acid is recom- mended by some operators, while others object to its use because of its coagulating effect upon the albuminoids of animal tissue. The object in sealing the dressing into the cavity with these substances is to secure rest to the pulp by preventing or lessening thermal shock, and also to prevent its further contamination with septic material, as by this method only can one expect to succeed in permanently allaying the irritation of the pulp and reducing its hyperaemic condition. Plugs formed of cotton saturated with gum sandarach cannot fulfil these requirements, for they soon become saturated with the secretions of the mouth and filled with myriads of or- ganisms, and should, therefore, never be employed in any case where the maintenance of aseptic conditions are desirable. The dressings should be allowed to remain undisturbed for two or three days or longer if the tooth continues comfortable, otherwise they may be changed every day. Care should be exercised in applying the dressing, and in each after-treatment, to prevent the entrance of moisture from the mouth. To insure this condition it is better to resort to the rubber dam than to rely upon napkins or other means for excluding moisture. If after a week's treatment the tooth remains in a comfortable condition, the pulp may be protected from thermal shock by varnishing the cavity and placing a layer of softened gutta-percha in the bottom of the cavity, and filling the balance with zinc oxyphosphate, or thin zinc oxyphosphate may be flowed over the bottom of the cavity and the balance filled with gutta-percha. The treatment of exposed pulps is given in a following chapter upon this subject. In those cases in which the hyiDcraemia is associated with abrasions, erosions, or superficial cavities the surfaces may be treated with carbolic acid (deliquesced crystals) or caustic potassa when located in the anterior part of the mouth, or with silver nitrate when located in unexj)osed posi- tions. Or a retentive form may be given to the denuded surface, the cavity thus made being first treated with carbolic acid and then dried, varnished, and filled with zinc oxyphosphate. When the irritation and hypertemia are due to the presence of large metallic fillings or to galvanic shock from contact of fillings of dissimilar metals, these should invariably be removed and replaced with non-con- ducting materials. Hyperaemia from Internal Local Causes. — Hypertemia of the pulp may be induced by certain internal causes, — viz., the formation of secondary growths within the pulp-chamber or within the parenchyma of the pulp itself. These growths are designated as dentinal tumors and pulp-nodules. Calcifications of the pulp resulting from the irritation of caries and other destructive loss of the hard tissues, and calcareous degeneration, are rarely, if ever, causes of hypersemia of the pulp, but are quite often the results of hypersemia. These formations have, however, been frequently found in teeth which DISEASES AND INJURIES OF THE DENTAL PULP. 385 had given no history of irritation or pain ; it has, therefore, been ques- tioned whether they are ever sources of hypersemia. Some have thought them to be the result of irritation and hypersemia, while others have be- lieved they may sometimes not only be the cause of this disturbance, but the more serious condition of facial neuralgia. This form of hypersemia is sometimes termed idiopathic, for the reason that there seemed to be no other disease uj^on which it was dependent for its origin or j^rogress. In a certain number of these cases there is not the slightest evidence of any external form of irritation whatever. In fact, the teeth are perfectly sound, the most careful examination failing to reveal the minutest trace of a break in the continuity of the enamel, either from caries, abrasion, erosion, or other injury. We must, therefore, in these cases, look for internal causes of irritation which are to be found in the presence of dentinal tumors and pulp-nodules. There are, however, no symptoms which are particularly or peculiarly diagnostic of these forms of irritation. The diagnosis must therefore be reached by a process of exclusion. The prognosis is decidedly unfavorable in this class of cases so far as 'the vitality of the pulp is concerned, for sooner or later the pulp succumbs to the irritation and devitalization takes place. Treatment. — The treatment of hypersemia due to irritation produced by the presence of secondary deposits within the pulp-chamber to be cura- tive must he radical. This consists of devitalizing and extirpating the pulp and filling the canals with suitable materials. Hyperaemia from Constitutional Causes. — General nervous irri- tability or neurasthenia is a term which has come into general use to indicate certain states of the nervous system — often inherited — the anatomic basis of which is still unknown, but which are characterized upon the one hand, as pointed out by Putnam, by a series of negative symj^toms manifested by a lack of vigor, efficiency, and endurance, affecting usually a large num- ber of nervous functions, and, upon the other hand, by signs of active derangement, which in part seem to occur as positive symptoms, and in part are due to a failure of the mutual support and control which the dif- ferent parts of the nervous systeni afford each other in health. These con- ditions are often manifest in the mentally and ]3hysically overworked, in low conditions of the general health, particularly in ansemic states of the blood, and in those suffering from prolonged wasting diseases, like tuber- culosis and cancer, or from digestive or intestinal derangements and fi'om nervous shock. I>feurasthenic i^atieuts are also subject to various sensory disorders like neu]'algic attacks and periodic headaches. Irritability of the spinal cord, which upon pressure xjroduces painful peripheral sensations in the region of the thorax or abdomen, according to the level at which the pressure is made. x\nother quite common variety of painful sensation, not precisely neuralgic in character, is a distressing sense of pressure and tenderness at the vertex or occiput, with stiffness of the muscles of the neck. Occasion- ally the pain is very severe, and entirely unfits the individual for the time for any form of physical or mental labor. 25 386 OPERATIVE DENTISTRY. Dr. Allbutt, in speaking of this class of individuals, says, ''They are heirs of every true neurosis, from insanity to toothache." Ilypercesthetic conditions of the peripheral terminations of the nerves, especially of the skin, are frequently met with in neurasthenic individuals. These conditions are characterized by an exalted or exaggerated sensibility of the skin, which is unattended by any observable structural changes whatever. In mild cases there is manifested an undue sensitiveness to contact with foreign bodies, such as the clothing, while in the severer cases the greatest distress is occasioned by even the passage of a feather over the surface. This disease is properly classed with the neuroses of the skin, and may be either idiopathic or symptomatic in its origin, but little is known of its etiology or pathology. Conditions similar to this are sometimes manifested in teeth which give no other evidence of disease ; teeth in which the integrity of the enamel has not been broken ; but it is an open question whether the sensation of pain is primarily due to an exalted sensibility or hypersesthesia of the den- tinal fibrillse, and located in them alone or in the pulp, the susceptibility of which has been abnormally increased to all forms of external irritation. Although the exact anatomic and histologic character of the dentinal fibrillse have never been i)ositively demonstrated, yet there is no good reason for doubting that they are terminal nerve-fibres, for they seem in many respects to possess in a high degree the functions of nerve-tissue. It is, therefore, not a severe strain upon the imagination to suppose the dentinal fibrillse capable of assuming an excessive sensibility or hyperses- thetic condition as an expression of the neurasthenic state of the patient, or that such expression may be primarily manifested in the pulp itself, which becomes abnormally sensitive to external impressions that under other conditions would cause no pain or uneasiness whatever. In those cases in which loss of substance has occurred in the crown of the tooth from caries or traumatism sufficient to expose the dentin, it would seem that the hypersesthesia begins in the dentinal fibrillae and ex- tends through them to the pulp. This view receives sui)port from the fact that if these cases are treated with silver nitrate applied to the exposed dentin, the hypersesthesia rapidly disappears and the tooth regains its normal sensitivity. General plethoric conditions of the system and pregnancy are often pro- ductive of hypersemic states of the dental pulp, by reason of the increased arterial pressure which accompanies these conditions. Some of the most obscure cases of odontalgia that the writer has ever had to deal with have been finally traced to one or the other of these conditions. Plethora may be defined as a condition in which the volume of the blood in the body is in excess of the normal amount (polywmia), and in which the vessels of the body generally, or of any part, are over-distended with blood. It is made manifest in flushing of the face, a sense of fulness in the head, buzzing in the ears, and full pulse, caused by the increased arterial tension and fulness or engorgement, particularly of the capillary system of blood-vessels. Plethora is more common in men than in women, and is most frequently DISEASES AND INJURIES OF THE DENTAL PULP. 387 seen in middle life. It has been stated by Jacobi that plethoric conditions are present in women just before the menstrual periods. Osier is of the opinion that the conditions which are denominated plethora are the result not of an actual increase in the volume of the blood, but rather to its distribution and certain local peculiarities of the vessels or of their innervation. Individuals of this dyscrasia are prone to capillary hyperseraia ; to rupture of the arterioles and capillary vessels and extravasations of the blood, by reason of the continued increased blood-pressure, and the con- sequent weakening of the walls of the vessels. This is illustrated by the fact that this affection furnishes a fair proportion of the otherwise healthy individuals who suffer from a general distention of the superficial vessels, hypersemia, and hemorrhagic conditions of the mucous membrane of the upper air- passages, as well as that more serious and often fatal aifection known as cerebral apoplexy. The tendency in plethoric individuals to general distention of the super- ficial blood-vessels and engorgement of the capillaries the writer believes sometimes results in hyperaemia of the j)ulp in perfectly sound teeth, accompanied by pulsating sensations, a sense of fulness or throbbing pain which may be referred to one or more teeth. In other cases it may result in rupture of the vessels, extravasation of blood, inflammation, and death of the pulp. The diagnosis of hypersemia of the pulp caused by plethora is quite readily made from the general condition of the patient, the absence of any discoverable external cause of irritation, and the previous history of the case, which is invariably a sense of fulness, accompanied with occasional pulsating or throbbing sensations in the tooth, which are augmented by vigorous exercise or the recumbent position ; later the pulsating or throb- bing sensations become painful, which indicates the establishment of the hypersemic state. Treatment consists in reducing general and local arterial tension. This may be accomplished in the first instance through a general depletion of the system by the administration of saline cathartics, a restricted diet, and regular exercise. Local arterial tension may be relieved by the hot foot- bath, keeping the extremities warm, the bowels open, and the skin free. If general treatment fails to give the desired relief and the pain continues, the only recourse is the devitalization and extirpation of the pulp. Pregnancy. — Pregnancy, although a physiologic process, is often pro- ductive of various disordered states of the system. It will be sufficient in this connection, however, to dwell simply upon those abnormal conditions of the oral cavity which are referable in a greater or less extent to the usual augmentation in the volume of the blood during this period, and to a plethoric state of the upper half of the body, which is not an infrequent accompaniment, and to those nervous phenomena which are productive at this period, of neuralgic conditions of the trifacial nerve. Changes both quantitative and qualitative occur in the blood during pregnancy. The quantitative change in the blood is proved by the in- creased area of the circulation brought about by the enlargement of the 388 OPERATIVE DENTISTRY. uterus and by the fulness of the vessels, a fulness which is sometimes pro- ductive of varicose veins or of serous effusion. This increase in tlie volume of the blood was first demonstrated by Spiegelberg and Gescheidlen * in experiments upon pregnant bitches. Authorities, however, are not agreed as to the qualitative changes which take place in the blood. Andral, f Nasse, X Meyer, § and others claim that the watery elements and the white corpuscles are increased and the red corpuscles diminished. lugerslev || was unable to detect any diminu- tion in the number of red corpuscles, while, upon the other hand, Fehling •[[ found the haemaglobin and the red corpuscles increased. Temporary hypertrophy of the left ventricle sometimes occurs as a result of increased labor thrown upon the heart as a consequence of the augmentation of the blood mass. This was first made known by Larcher ** in 1828. Venous congestion, varices, and swelling of the lower extremities, and arterial hyperemia of the upper half of the body, are a frequent accom- paniment of pregnancy. The causes of these conditions are not fully understood, but they were attributed by Christoforis ff to pressure of the gravid uterus upon the iliac veins, which prevented the normal return of the blood to the inferior vena cava, and to pressure upon the descending aorta, thus obstructing a normal flow of blood to the lower extremities, and causing plethora or arterial hypersemia of the upper portion of the body. An increase in the salivary secretions is often a noticeable symptom. Ptyalism when present manifests itself early, and usually disappears spon- taneously between the third and fourth months. It occasionally i)ersists, however, in an exaggerated form during the entire period of gestation, and even for several weeks thereafter, while the amount secreted may be so great as to endanger the life of the j)atient. The qualitative changes in the saliva during pregnancy are sometimes quite marked. The water is increased, while the organic and inorganic elements are diminished. Schramm rei)orted one case in which the pytalin was entirely absent. In those cases in which an excessive flow of saliva is manifest the buccal mucous membrane is more or less inflamed, the parotid, submaxillary, and sublingual glands are swollen, tender, and quite painful when their secre- tory functions are especially excited.- Fcetor is not present, and the absence of this symptom distinguishes it from mercurial ptyalism. The cause of this disorder is generally thought to be due, in all proba- bility, to a reflex neurosis, though the writer is inclined to the opinion that it is due to over-stimulation of the glands resulting from the general hyper- * Hirst's American System of Obstetrics, p. 353. t Amiales de Chimie et de Physique, Juillet, 1842. X Archives of Gyn., Bd. ix. S. 338. I Untersuchungen iiber die Veranderungen des Blutes in der Schwangerschaft. II Centralb. f. Gyn., 1879, p. 635. f Archives f. Gyn., Bd. xxviii. Heft 3, S. 454. ** Hirst's American System of Obstetrics, p. 346. tt Ibid. DISEASES AND INJURIES OF THE DENTAL, PULP. 389 femic condition of all the tissues of the uj)per portion of the body during this period. The affection frequently reappears in successive pregnancies. Gingivitis is another common oral symptom in pregnancy, and is often present when there is no indication of salivation. These cases are charac- terized by redness and tumefaction of the gums and a tendency to bleed on slight pressure or friction, while the secretions of the mucous glands are often decidedly acid in reaction. Phagedenic pericementitis is occasionally an accompaniment of preg- nancy, and is frequently associated with rheumatic affections, diabetes mellitus, and albuminuria, but just how it is associated in relation to cause and effect with the kidney aifections is not i^ositively known, but the writer has suggested '!" that "it is due in these cases to the accumula- tion of effete products in the system, possibly of uric acid, urea, and other waste material." JSTeuralgic affections are also quite common during j)regnancy, and most frequently affect the face and head. Odontalgia is a not infrequent accom- paniment of pregnancy in teeth which, so far as external conditions are presented, appear to be x)erfectly sound. This affection is due to hyi^er- semia of the pulp induced by the augmentation in the volume of the blood, the increased arterial pressure, and general hypersemia of the upj^er por- tion of the body. The proof of this statement is in the fact that a brisk cathartic will often relieve or entirely control an attack of odontalgia when due to these causes. It operates in a general way by depleting the circulation, thus relieving the arterial tension and hypersemia ; while it acts locally by re- ducing the blood-pressure in the pulj), and restoring for the time being a normal circulation. On the other hand, anaemic states of the blood are prone to establish general and local neuralgic conditions. Anstie has graphically epitomized the definition of neuralgia as " the cry of the hungry nerves for food. ^^ The trifacial nerve is frequently the seat of neuralgia, the pain often being located in one or more teeth. Cases are on record in which tooth after tooth has been extracted under the belief that hyperaemia or inflammatory conditions were present in the pulp of such teeth, when in reality the cause of the atfection was a general one, due to an impoverished condition of the blood, which in many cases could undoubtedly have been relieved by approi^riate general tonic treatment. Eeflex neuralgic phenomena in the teeth are occasionally encountered as a result of diseased conditions of remote organs, or of hyj)erplastic or hj^per- trophic enlargement of j)ortions of tissue or organs, or of new growths, which cause i^ressure upon important nerve-trunks, or upon the nerves directly supplying the teeth. Consequently in the diagnosis of all obscure cases of odontalgia due weight should be given to the possibility of the affection having its origin in some one of these remote causes. * Paper on "The Teeth of Pregnant Women," Transactions of the American Med- ical Association, 1889. 390 OPERATIVE DENTISTRY. Fig. 486. NEW FORMATIONS. Calcic Formations within the Pulp-Chamber. — The formation of secondary growths of dental tissue within the pulp-chamber and calcic degenerations of the tissues of the pulp have never been satisfactorily classified. Salter was the first to attempt to classify the vari- ous forms of new growths within the pulp-chamber, and for many years it was the only classification used. Black has since made a more minute and comprehen- sive classification, but this, he thinks, is still far from complete or satisfactory. Salter divides secondary growths of dentin into three different forms, — viz., dent in of t^epair, dentin ex- crescence, intrinsic calcification, or osteodentin. The accom- panying illustration (Fig. 486), borrowed from Salter,* represents these forms of secondary growths in the pulp-chamber : a represents a mass of dentin of repair formed to compensate for the wear at the summit of the cusp ; 5, an excrescence or tumor projecting from the side of the cavity into the pulp ; c, represented by the dark cylinder in the axis of the pulp, indicates where the formation of osteodentin or intrinsic calci- fication begins. Dr. Black f classified the secondary deposits within the pulp-chamber under six different forms, — viz. : *'!. Secondary Dentin. — A new growth of dentin more or less regular in formation, excited by abrasion, decay, or other injury, by which the dentinal fibrils are subjected to irritation at their distal ends. "2. Dentinal Tumors within the Fulj)- Chamber. — ^An erratic growth of dentin into the pulp -chamber united to the wall by a pedicle. The structure is very irregular. ^'3. Nodular Calcifications among, hut not of, the Tissues of the Didj). — These are the irregular nodulated masses so frequently seen either as very small stones or irregular masses. They contain many calcospherites. ''4. Interstitial Calcifications of the Tissues of the Pit/^9.— These are the counterpart of calcifications elsewhere in the body, as in the arteries, etc. "5. Cylindrical Calcifications of the Pidp. — The tissues in this form ai'e probably in a state of fibrous degeneration, which is usually seen in the pulp- canals. ^'6. Osteodentin. — Erratic formations showing both the lacunte of bone and the dentinal tubes." Calcospherites were seen by Black in connection with many of these forms. Other irregular formations are found that are scarcely assignable, he thinks, to any of these varieties, and it is not unusual to find the vari- ous forms intermixed with each other. * Dental Pathology and Surgery. t American System of Dentistry Pulp-chamber indarr deritic Fig. 487.— Secondary dentin on wall of pulp-chamber. (V. A. Latham.) X 100. Secondary dentin --:%." .'^^'^l Pulp-chamber ff-:. f. ''•uj .Ki.<-. I Fig. 488.— Secondary dentin on wall of pulp-chamber. (V. A. Latham.) " • 9fl. Pulp-chamber Pulp-chamber Pulp-chamber Secondary dentin Fig. 489.— Secondary dentin in base of pulp-chamber. (V. A. Latham.) x 50. Pulp-nodule ■1^- Dental pulp Fig. 491.— Section of dental pulp containing a pulp-nodule. (V. A. Latham.) x 23. DISEASES AND INJURIES OF THE DENTAL PULP. 391 Secondary dentin, or dentin of repair, may be distinguished from tlie other forms of secondary deposit by the fact that it is always located oppo- site some lesion of the external tissues of the tooth, whereby a loss of continuity has occurred ; that it is adherent to and in direct structural con- tinuity with the primary dentin ; that the pulp is not attached to, nor is its structure involved in, the newly formed mass, but may be easily removed. This process may be regarded as physiologic, having a similar signifi- cance to the process of repair exhibited in bone-tissue. For further discussion of this subject, see chapter on "Conservative Treatment of the Pulp." Dentinal Tumors. — These are rare forms of secondary growths within the pulp-chamber. They are composed of calcific material of notably irreg- ular structure, formed in masses of varying size, and attached by a pedicle to the primary dentin, or occasionally to masses of secondary formation. They are confined entirely to the pulp-chamber. The dentinal tubes within the mass are continuous with the tubules of the primary dentin (Fig. 487). Dr. Black is of the opinion that they are the result of the same causes as those leading to the formation of secondary dentin generally. With this opinion the writer cannot fully agree, for the reason that such growths have been occasionally found in teeth in which there were no evidences of any external cause of irritation. Of the circumstances which determine the erratic tumor-like form of the growth nothing whatever is definitely known. Figs. 488 and 489 show two very erratic forms. Wedl and Heider believe it is due to an inversion of the layer of dentinal cells, and that the space formed within the surface of the pulp by the inversion is later occupied by new dentin. They say, ' ' These formations are by no means of rare occurrence, and that they are found attached to the original dentin by means of a pedicle, and in cases where there is no con- nection with a pedicle detachment has ensued." ^^' Nodular Calcifications, or Pulp-Stones. — These are found in globular masses (Fig. 490) and spindle-shaped masses scattered through the substance of the pulp, par- ticularly in the teeth of adults. They may be found in any part of the pulp-tissue, but most often in the coronal portion. In form they are irregularly nodulated, appear- ing to be made up of an aggregation of smaller nodules. In structure they appear to be masses of calcific material composed of the same elements as dentin, but lacking its peculiar structure. Embedded within the calcific material are numerous bodies made up of concentric rings, which are calcosphe- rites. Various irregular lines are seen running through the mass, which may be tubules or only faults in the structure. The formation of pulp-nodules is thought to be due to the deposition of masses of calcoglobulin within the pulp, and which is known to form the base of the pulp-nodule, — the calcospherite, enamel, dentin, and bone, — the lime-salts entering into combination with the calcoglobulin to form calcospherites, and these uniting in larger masses form the pulp-nodules. 392 OPERATIVE DENTISTRY. Wedl, Salter, Black, and other writers look upon their presence in the tissues of the pulp as a result of some form of peripheral irritation of the dentinal fibres, as they are found in increasing numbers in the teeth of those who have suffered from caries, abrasion, erosion, inflammatory con- ditions of the pericementum, or other injury or disease. Figs. 491 and 492, which show a pulp-nodule m situ, are made from a pulp removed from a tooth which was the subject of pyorrhoea alveolaris. Tomes does not quite a"-ree with this view, as he found globular masses in three out of five speci- mens of perfectly sound molar teeth removed post mortem from subjects in the hospital morgue. Eobin and Magitot called attention to the pres- ence of isolated calcareous granules of globular form which were scattered through the substance of the pulp in the early stages of dentin formation. Henle and others have likewise described them as present in the teeth of man, ruminants, and rodents. C. S. Tomes found them in the developing teeth of ruminants,, scattered freely through the dentinal pulp, and finally becoming embedded at various depths within the substance of the dentin. The fact, therefore, remains that many cases of calcific nodular forma- tions within the pulp have their origin in other than external causes of irritation. Black looks upon the presence of a few pulp-nodules in the tooth as of no special pathologic significance as far as the future health of the tooth is concerned. Calcification of the Tissues of the Pulp. — This is a condition often seen in the teeth of elderly persons, as the result of senile change or de- generation of tissue. Fibroid degeneration (Fig. 493) is one of the most common precedents of calcareous deposits in the pulp. Calcareous deposits formed within the structure of the tissues, according to Ziegler, usually occur in localities where the tissues have already lost their vitality or are in a process of degeneration or necrobiosis. It appears as if dying tissue which has undergone more or less modification possesses a kind of attraction for the lime-salts which are in solution within the body, and enters into intimate combination with them. The tissues which are most prone to calcareous degeneration are connective tissue which has undergone hyaline degeneration or sclerosis, the walls of blood-vessels, tumors, and other portions of the body which are undergoing hyaline or fatty degeneration, degenerating cartilage, dead cell-bodies, and cheesy areas of considerable size. Tissue-calcification is uniformly associated with degenerative changes in the structures of the pulp. Calcification may affect small or large areas, causing in the latter case a distinct hardening of the tissue and a whitish coloration. The process is characterized by the formation of numerous minute islands of calcification scattered through the tissue of the pulp, of regular outline, and presenting a smooth surface. There is considerable difference in the microscopic appearance of these islands of calcification. In some of them are seen on section the calcified tissue elements of the pulp, others appear to be of granular structure, with a few irregular and wavy tubes scattered through them, and still others appear to have no structure at all. Pulp-nodule Fig. 492. — Vertical section of dental pulp, showing^ puli>nodule. (V. A. Latham.) ■it, Fig. 4'.'3.— Section of tooth-jiulp undergoing fibroid degeneration. (V. A. Latham.) >' UO. DISEASES AND INJURIES OF THE DENTAL PULP. 393 Salter aud Black both describe a peculiar form of degenerative calcifi- cation occurring in tlie radial portion of the pulps of teeth, particularly in the roots of the molars, which they have termed cylindrical calcification. Fig. 494. Cylindrical calcification of the pulp, early stage. (After Dr. Black.) From the apj)earances exhibited in sections of cylindrical calcification, it is evident that it is a calcareous degeneration of a previous fibrous degeneration of the pulp. This is shown in the accompanying illustrations by Dr. Black. Pig. 494 shows an early stage of the degenerative process ; Fig. 495. Cylindrical calcification of the pulp, early stage ; nodules teased apart. (After Dr. Black.) Fig. 495 is a similar section in which the nodules have been spread out to show the attachment of the cylindrical masses to the fibrous elements of the pulp ; while Fig. 496 shows a more advanced stage of the disease in which the cylinders run together and join end to end, forming jointed rods, but do not coalesce. In this stage of the disease the radial portion of the pulp becomes stiffened and may be bent at various angles, and will retain its bent position. Salter says— and Black agrees with him— that ultimately "the whole of the tissues, cells, nuclei, connective tissue, blood-vessels, and multitudes of neri^es are swallowed up and obliterated in the calcific 394 OPERATIVE DENTISTRY. process. The process of calcification is clearly not interstitial in the sense of being between the fibres." This variety of calcification is usually asso- ciated with other forms, and there is generally more or less calcification of the coronal portion of the pulp, either in the form of secondary dentin or Fig. 496. Cylindrical calcification of the pulp, advanced stage. (After Dr. Black.) interstitial calcification. Figs. 497 and 498 illustrate such a condition, the coronal portion of the pulp being completely calcified. Osteodentin is a secondary formation of rare occurrence in the humaji teeth, but it is common in the teeth of animals, particularly in very large Fig. 497. Fig. 498. animals, like the elephant. These formations are the result of long- con- tinued or chronic irritation. As its name implies, it is a form of secondary growths which combine the elements of both dentin and bone, or, more correctly, of cementum (Fig. 499). It is develoj)ed, according to Salter, by the general conversion and intrinsic calcification of the several tissues of the pulp. It is usually vascular, frequently arranged in systems around vessels, like the Haversian systems of bone, and it sometimes has true lacuuse. It has fewer dentinal tubules than any other form of dentin, and is usuallj" very transparent. It is made up of various calcification islands or systems of secondary dentin, which are finally fused together and ad- herent to the primary dentin (Fig. 500). The mass may contain any number of Haversian systems and numerous true bone lacunae, especially resembling those found in the cementum. These masses of osteodentin are found in teeth which show marked DISEASES AND INJURIES OF THE DENTAL PULP, 395 evidences of a former resorption of dentin, and although in many cases the tissues increased in amount, a considerable portion was found to occupy Fig. 499. Section of osteodentin. (After Salter. ) the situation of the normal dentin which had been removed by the pro- cess of resorption. Bodecker^^ has also described this form of new growth as secondary dentin with forms analogous to Haversian systems. Fig. 500. Section of obteodcutiu. (.Alter female and Colyer.) Occasionally the resorbed dentin will be replaced by bone. Fig. 501, which is taken from the '' Transactions of the Odontological Society of Great Britain," 1893, shows a section made from a partially erupted tooth, * Dental Cosmos, 1879. 396 OPERATIVE DENTISTRY. the root of which had apparently been about two-thirds formed, and ap- peared as though it had been fractured, but upon microscopic examination it was found that this appearance was due to resorj)tiou. The bone-tissue occupies the cavity formed by the process of resorption. Fig. 501. Section of dentin showing resorption area occupied by bone-tissue. (After Smale and Colyer. ) Irritation and hyperemia of the pulj), it will be seen from the fore- going descriptions, could hardly occur from any of the various forms of secondary deposits except those mentioned under the head of internal local causes, — viz., dentinal tumors and pulp-stones, — by reason of the fact that all the other forms of secondary deposits are conversions of tissue, while these are erratic growths, occupying space in the x^ulp-chamber or in the tissue of the pulp, where they produce pressure upon the nerve- filaments, causing irritation. CHAPTEE XXIV. INFLAMMATION OF THE DENTAL PULP. Definition. — Inflammation (Latin, inflammatio, from inflammare, to in- flame ; injiammo, I set on fire), is a condition of nutritive disturbance, char- acterized by hypersemia, with proliferation of the cells of a tissue or organ, and attended by one or more of the symptoms of pain, heat, swelling, dis- coloration, and disordered function. Inflammation is a series of changes in a part identical with those which are produced in the same part by injury from a chemic or a physical irritant. Pulpitis is the term applied to inflammation of the dental pulp. (Latin, pulpa, pulp, and itis, a suffix used to indicate inflammation.) Physical Signs. — The physical signs or cardinal symptoms of inflam- mation, as described by Celsus, are four in number, — viz., rubor, tumor, calor, and dolor, redness, swelling, heat, and pain ; a fifth symptom has since been added to complete the description of the physical phenomena as presented in the tissues, — viz., functio loesa, disturbance of function in the part. Inflammation is a symptom of disturbed function, but not a disease. It is an effort upon the part of the system to eliminate or render inert or harmless the primary cause of the disturbance. All forms of inflammation are the result of the action of certain forms of irritation. Irritants are classed under four general heads, — viz., mechanic, chemic, septic, and nervous. Mechanic irritants produce irritation through their mechanic action. Examples : the presence of foreign bodies, pressure from external sources, pressure from new growths, traumatisms, accidental or surgical, etc. Chemic irritants are substances which irritate by virtue of their chemic reaction upon the tissue elements with which they come in contact. Ex- amples : alkalies, acids, and escharotics, like chromic acid, or certain coagulants, like carbolic acid and silver nitrate, or violent irritants, like croton oil and cantharides. Other examples are found in drugs which through their constitutional exhibition produce peculiar effects upon cer- tain tissues and organs, and which if administered in toxic doses will cause inflammation. Mercury acting upon the tissues of the mouth and salivary glands produces stomatitis and salivation. Cantharides will cause irrita- tion of the urinary organs, ergot of the uterus, and uric acid will produce gouty inflammations. The toxic inflammation caused by the poison of serpents and certain insects, the poisonous action of certain plants, like the Bhus toxicodendron, and the ptomaines are examples of still other groups of chemic irritants. Septic irritaiits are living organisms, — parasites or micro-organisms, — which cause irritation by their presence in the tissues or by the elabora- 397 398 OPERATIVE DENTISTRY. tion of toxic substances — ptomaines — as waste products and their intro- duction into the system by absorption. The pus- microbes and the sapro- phytic germs belong to this class. Nervous irritants are those which produce irritation through the medium of the nervous system by disturbing the normal functions of the part. The influence which is exerted by the nervous system over the functions of nutrition, both generally and locally, in the production of inflammatory symptoms has long been recognized. Impairment of the nutrition of the skin is sometimes observed to follow injury of the nerves supplying the part. Degenerative changes have been known to take place in the pulps of the lower teeth following exsection of the inferior dental nerve. Eeflex nervous conditions are also recognized as being productive of inflammatory phenomena. An instance in point is the nervous irritation sometimes caused in the dental pulp by a misplaced uterus or the condition of pregnancy. Herj)es zoster is an example of a pustular eruption following the course of a nerve, the inflammation being accompanied with infiltration of leucocytes around both the terminal branches and the trunk of the nerve. Inflammation is a process which may affect any tissue of the body having a vascular circulation or which is connected with blood-vessels. Enamel which has no vascular circulation and is in no way connected with blood-vessels cannot be the seat of inflammation. Dentin, which occupies a position midway between enamel and bone in the evolution of the calcareous tissues, presents conditions which are thought by certain authorities — Heitzmann, Abbot, Bodecker, and others — to be inflammatory in their nature, the peculiarities of the symptoms being due to the low state of vitality and the small percentage of organic matter contained in its structure. Inflammation in vascular tissues usually begins with the phenomena of hypersBmia, and progresses to exudation or to suppuration ; sometimes reso- lution takes place, at others leading to the production of new formations, or to metamorphoses of various kinds, or to devitalization and destruction of tissue, and creating a more or less serious disturbance of the functions of the parts. The inflammatory process may vary greatly in its character and in its location. The histologic character of inflammations depends upon two factors, — the nature of the exudation and the changes in the tissues. Both are used to classify the various forms of inflammation, according as the one or the other seems to be most pronounced. Exudation. — Exudation or diapedesis is the process by which during partial stasis of the blood-current the corpuscular elements of the blood (the leucocytes and phagocytes) and the liquor sanguinis pass through the walls of the blood-vessels into the tissue spaces beyond. This process is the result of changes in the vessel walls, which permit the passage or leakage of the elements of the circulating fluid through the walls of the vessels. Ziegler says, ' ' It may be accepted as an established fact that in inflammation the vessel wall is affected, but it is still questioned by some whether the affection is of the nature of a chemic alteration or a mere INFLAMMATION OF THE DENTAL PULP. 399 widening of pre-existing intercellular spaces." Bnrdon Sanderson believes ' ' it is due to the loss of the power by the vessels of resistance to dilatation, and the loss of vital power, in consequence of which leakage takes place." Rupture or rhexis of the vessel walls sometimes takes place, which permits the red blood-corpuscles to escape into the tissues. Tissue Changes. — The cellular and fluid exudates which pass through the vessel walls collect first in their immediate neighborhood, but rapidly spread out and involve surrounding healthy tissue by occupying the lymph-spaces of the tissues. When this tissue infiltration is considerable it is liable to produce other disturbances of circulation and nutrition, and thus increase the area of the inflammatory exudation and tissue degeneration. Among the earliest changes which take place in the inflamed tissue is the coagulation of the fibrinous elements of the exudate, which prevents, the further movement of the migrated corpuscles by enclosing them in the^ coagulated mass. One of the functions of the leucocytes is to take up solid particles and portions of broken down and disintegrated blood-corpuscles. Metchnikoff (1884) and his followers claim that they have also the power of englobing and destroying the invading pathogenic bacteria which have gained an entrance to the blood and other tissues of the body. And that by this phagocytic power of the leucocytes immunity was established in the organism. He found in certain observations made ujDon a species of daphnia, which is subject to infection by a torula resembling the yeast fungus that gains access to its body through its food, that the fungus penetrates the walls of the intestines and invades the tissues. In certain cases the infection was not fatal, and this he believed was due to the fact that the leucocytes which accumulated around the invading fungi seized upon these organisms, and eventually destroyed them. If the leucocytes, were successful in overpowering the i:)arasites, the animal recovered ; if not, the infection proved fatal. From this he argued that the pathogenic bacteria, when introduced into the body of an immune animal, are de- stroyed in a like manner, while they play an active part as prophylactic agents and in the metamorphosis of tissues and organs in inflammation. Metchnikoff explained that the leucocytes gathered up the bacilli and destroyed them by a process of internal digestion. This power of the leucocytes to destroy foreign substances was first suggested by Surgeon- General Sternbergh, of the United States army, in 1881. • There is still a difference of opinion as to the power of the leucocytes to destroy living bacteria. Koch found in 1878 that the bacteria multiplied within the body of the leucocytes, and that many of these cells were de- stroyed by the bacteria. Sternbergh, Weigert, Baumgarten, and others, have maintained that the bacteria found in the leucocytes were already dead when taken up by these cells, their vitality having been destroyed by some agency outside of the leucocytes, namely the blood-serum, and that there is abundant experi- mental evidence to prove that the blood-serum has decided germicidal power. 400 OPERATIVE DENTISTRY. Sternbergh says (1892), "Numerous experiments have been made during the past two or three years with the view of determining whether x>atho- genic bacteria are, in fact, destroyed within the leucocytes after being picked up by them, and different experimenters have arrived at opposite conclusions. In the case of mouse septicaemia, and in gonorrhoea, one would be disposed to decide, from the appearances and the arrangement of the pathogenic bacteria in the leucocytes, that they are not destroyed, but that, on the other hand, they multiply in the interior of these cells, which in the end succumb to this parasitic invasion. In both of the diseases mentioned we find leucocytes so completely filled with the patho- gejiic micro-organisms that it is difficult to believe that they have all been picked up by a voracious phagocyte which has stuffed itself to repletion, while numerous other leucocytes from the same source and in the same microscopic field of view have failed to capture a single bacillus or micro- coccus. Moreover, the staining of the x)arasitic invaders and the charac- teristic arrangement of the gonococcus in stained preparations of gonor- rhoeal pus indicate that their vitality has not been destroyed in the interior of the leucocytes or jDns-cells, and we can scarcely doubt that the large number found in certain cells is due to multiplication in situ rather than to an unusual activity of these peculiar cells. But in certain infectious dis- eases, and especially in anthrax, the bacilli included within the leucocytes often give evidence of degenerative changes, which would support the view that they are destroyed by the leucocytes, unless these changes occurred before they were picked up, as maintained by JSTuttall and others." Nuttall (1888) has shown that the destruction of virulent micro-organ- isms in the blood of animals was not dependent alone upon the immediate presence of living leucocytes, but that the serum of the blood, when freed from all cellular elements of any kind, still possessed the power of de- stroying the vitality of bacterial forms equal to that of the blood in its normal state when all of its constituent elements were present. Buchner (1890) demonstrated that the serum was robbed of its germi- cidal properties by exposure to a temi)erature of 55° C. for half an hour. Its efficiency, on the other hand, was not impaired by alternately freezing and thawing it, but dialysis or extreme dilution with distilled water dimin- ished its germicidal power or completely destroyed it. If, however, it was diluted with an equal amount of water containing from 0.6 to 0.7 per cent, of sodium chloride, its germicidal action was in no way diminished. From this he concluded that the active agent in the blood which gave it this germicidal power is a living albumin, and that an essential constituent' is sodium chloride, the removal of which, either by dialysis or dilution, robbed the blood of its germicidal power. These elements or constituents of the blood which possess the power of destroying pathogenic micro- organisms he termed "alexins." Hankin, Martin, and Ogatta (1891) have succeeded in isolating ferment- like "globulins," which in solution possess active germicidal powers. Later, Vaughn, ^ovy, and McClintock have found in their observations that the nucleins are the most important germicidal and protective agents possessed by the body ; that this bacterial constituent of the blood-serum INFLAMMATION OF THE DENTAL PULP. 401 is not a serum albumin, but that it is a proteid, for it is destroyed at 60° C. ; and that it is probably a nuclein, for it is not destroyed by gastric digestion. The nuclein which they isolated was found to possess most powerful germicidal properties when tested upon Koch's comma bacillus, the strepto- coccus ]^yogenes aureus^ and the bacillus anthracis. If resolution now takes place the blood- current gradually resumes its natural flow, resorption of the exudates begins, the induration and swell- ing disappear, the pain ceases, and the tissues regain their normal color and functions. If, on the other hand, stasis becomes complete in a limited inflamed area, suppuration is established, first, by the death or necrosis of the exuded blood-cells and of the embryonal and fixed tissue-cells, — necrobiosis, — and secondly, by the liquefaction and complete dissolution of the tissue ele- ments, the leucocytes and embryonic cells formed from the fixed tissue-cells —phagocytes — being converted into pus-corpuscles and the intercellular substance of the tissues liquefied. Complete stasis occurring in larger areas may result in death of tissue en masse; when this occurs in soft tissues it is termed gangrene; when occurring in bony tissues it is termed necrosis. Another change which may take place in the inflammatory exudates is that of fatty degeneration. This is a process of retrograde change by which the albuminoid elements of the tissues and the exudates are converted into granular fatty matter. Pus, tubercles, etc., are sometimes converted into soft, cheese-like masses by a degenerative change known as caseation. Hyperplasias, or Tiypertropliies of tissue, are not uncommon sequelae of in- flammation. Hyperplasia is an increase of the elements which compose a tissue or an organ, resulting in an increase in the volume of the tissue or organ, and may be due either to over-stimulation, over-nutrition, irrita- tion, or a low form of inflammation. Polypus of the pulp, enlargement of an irritated gum festoon, and hypercementosis are examples of this condition. New formations resulting from inflammations are due to a proliferation of embryonic cells and their organization into new tissue, sometimes simi- lar in kind, but often of a different character from the tissue in which they originate, resulting in the formation of tumors of various kinds, some benign, others malignant. Examples of the former variety are the calcareous formations developed within the pulp-cavity ; and of the latter, good examples of the benign tumors are found in the fibromas which sometimes occur upon the gums, and the malignant varieties are well shown in osteosarcomas of the jaws and in eiDitheliomas of the lips. Inflammation is usually divided into two forms, — viz., acute and chronic, — and these again into many varieties, according to the anatomical location of the process, as taught by Virchow, such as catarrhal, fibrinous, paren- chymatous, phlegmonous, indurative, degenerative, scrofulous, and infec- tive. 26 402 OPERATIVE DENTISTRY. Ill acute inflammation the process runs a more or less rapid course and the symptoms are marked, while in the chronic form the symptoms are all less prominent, and any one or all of the cardinal symptoms may be so slightly developed as to escape notice altogether. A form between these two conditions has been denominated subacute inflammation. TABLE OF INFLAMMATORY PHENOMENA. Summary of steps : . Traumatic 1. Irritants. h. Chemic. c. Bartoric or septic. d. Electric. e. Thermic. Irritation. Determination or active hyperaemia. Disturbance of circulation. Increased motion and retardation or oscillation. 6. Stasis (partial). 7. Vascular dilatation. 8. Exudation, — diapedesis, i-hexis. 9. Swelling, — cedema. a. Eesolution, or absorption or organization. h. Fibroid thickening or chronic inflamma- 10. Terminations. -{ tion. c. Suppuration. d. Abscess, — necrosis. e. Ulceration. ./. Gangrene. a. Vascularization. h. Granulation, c. Scar-tissue. Hyperplasia. New formations. INFLAMMATION OF THE PULP. Etiology. — Inflammation of the pulp may be either acute, subacute, or chronic in form, and each of these varieties may involve only a limited area of the pulp, when it is termed circumscribed inflammation, or it may involve the whole of the organ, when it is termed diffuse or general inflam- mation. Acute ^pulpitis is in a very large majority of cases due to exposure of the pulp, either from caries, fracture of the crown, mechanical abrasion, or erosion. About ninety-six per cent, of the primary cases, according to the records of the writer, are due to exposure from caries ; about three per cent, to fractures, abrasions, erosions, and other injuries of a traumatic nature involving a loss of tissue ; and one per cent, to constitutional con- ditions, such as plethora, pregnancy, nervous irritability, and kindred affections. These figures accord very closely with those of Tomes,* who says that "ninety-nine out of every one hundred cases are due to exposure of the pulp."' * Tomes's Dental Surgery, 4th edition, p. 380. INFLAMMATION OF THE DENTAL PULP. 403 In those cases which develop after the carious cavity has been filled, — secondary cases, — minute exiDOSures of the pulp involving one of the cornua, — incomplete exposures, or pseudo-exposures, — which permit pressure to be exerted upon the pulp by reason of the thinness and decalcified condition of the wall of the pulp-chamber, and thermal shock aggravated by the presence of metallic fillings are the principal causes ; the latter, however, are the most prolific of inflammatory conditions, by reason of the fact that in incomplete and pseudo-exposures the pulp has generally been protected by some form of non-conducting capping, which in a measure prevents or lessens thermal shock in these cases. Exposure of the pulp to the fluids of the mouth permits the entrance of the pyogenic micro-organisms and establishes septic inflammation, which almost invariably terminates in suppuration. It is possible, however, for a septic inflammation to occur in the pulp without direct exposure of any part of this organ : first, by the penetration of the softened and decalcified dentin by the pyogenic or pus-producing micro-organisms which in their growth follow the dentinal tubuli, thus gaining access to the tissues of the pulp ; secondly, by the presence of these organisms in the blood, which have gained access to this fluid through some external wound or abrasion of the skin or mucous membrane, or from some pre-existing suppurating wound or abscess, forming secondary abscesses just as metastatic abscesses are formed in other portions of the body by the lodgement of these organ- isms in the capillary blood-vessels or glandular structures, forming a nidus, where, under favoring conditions of a weakened local vitality, they rapidly propagate. Pathology. — Inflammation of the dental pulp is in no way different from inflammation as observed in other connective tissues. It follows the same course, by the establishment of hypersemia, the exudation of leu- cocytes and their proliferation, the formation of infarcts, the escape of red blood- corpuscles, the coagulation of the fibrinous elements, and either resorption ending in resolution, the organization of the escaped cells into new tissue, the liquefaction of the exudates and the formation of pus, the death of the puli^ en masse, followed by putrefaction — moist gangrene— and the formation of mephitic gases in those cases in which the pulj) has been exposed to septic influences, or by mummification — djy gan- grene — in those cases in which the pulp has not been exposed to septic infections. Acute Circumscribed Pulpitis. — Acute circumscribed infiammation of the pulp is usually found in those cases in which the walls of the pulp- chamber has been perforated, exposing the surface of the pulp at this point to external irritating and septic influences. The area thus affected is sometimes very minute ; at others it involves a considerable portion of the surface of the pulp. The microscope reveals in the early stage of the inflammation a more or less extensive area immediately beneath the in- flamed surface, occupied by the inflammatory exudates, and smaller areas, which are colored red, the result of the formation of thrombi and infarcts and the escape of the red blood- corpuscles. Suppuration is later established upon the surface, and minute coUec- 404 OPERATIVE DENTISTRY. tions of pus-corpuscles may be fouud in the deeper structures of tlie organ. The character of the iuflammation now depends upon the extent of the opening in the pulp -chamber, the activity of the phagocytes, and the dyscrasia or diathesis of the patient. When the perforation in the wall of the pulp-chamber is so small as to prevent a free escape of the pus which is formed at the point of exposure the suppurative inflammation becomes more acute, and the entire pulp is soon involved, ending in its speedy destruction. But when the perforation is so large that the pus formed upon the surface finds a ready exit, the suppurative process is apt to be prolonged for an indefinite period, the character of the process be- coming subacute or chronic in its manifestations with the formation of an ulcerating surface. On the other hand, if the patient is of a scrofulous, tuberculous, or syphilitic diathesis, or is suffering from malaria, diabetes mellitus, or albu- minuria, the suppurative inflammatory process will run a rapid course, ending in a few days at most in the destruction of the pulp ; while if the individual is in fair health and of good constitution, the tendencies are towards resolution or a subacute or chronic inflammation. Acute Diffuse or General Pulpitis. — Acute diffuse or general inflam- mation of the pulp is the most common result of all forms of irritation of whatever nature, whether mechanic, chemic, septic, or nervous. It may occur, as already pointed out, with or without perforation of the pulp- chamber. The character of the inflammation is such that it speedily causes stasis of the blood-current by general infarction or thrombosis, unless the per- foration in the wall of the pulp-chamber is sufficiently large to permit expansion or swelling of the tissues to a degree that will relieve the press- ure upon the blood-vessels at the apical end of the pulp- chamber. The result of general infarction is death of the pulp en masse. Inflam- mation, however, both acute, circumscribed, and diffuse, may be induced by infarcts in limited areas within the body of the pulp, caused by intense hypersemia, as pointed out by Black.* Extravasation of red blood- corpus- cles and their disintegration frequently occurs as a i-esult of infarction. The disintegration of these corpuscles and the dissemination of their col- oring matter through the substance of the dentin exi3lains the jDinkish hue which often obtains after the death of the pulp, and which, from the grad- ual decomiDOsition of the haemoglobin thus disseminated, progressively changes the color of the dentin to brown, blue, and blue-black. Symptoms and Diagnosis. — The symptoms of acute pulpitis must be studied from two aspects : first, those cases in which there is no exposure of the pulp ; second, those which present exi^osure and are necessarily septic. The symptoms of inflammation of the pulp are so nearly like those of hypersemia that differentiation between them becomes extremely difficult. Black thinks that in pulpitis the pain is less paroxysmal and more inclined to be prolonged. * American System of Dentistry, vol. i. p. 846. INFLAMMATION OP THE DENTAL PULP. 405 On account of the unyielding nature of the walls of the pulp-chamber the symptoms of acute pulpitis are generally active and violent, and are characterized by sharp, stinging, lancinating, throbbing pain, at times continuous ; in other cases the pain may be paroxysmal in character, in- creasing in intensity until it becomes almost unbearable, then slowly sub- siding, the exacerbations occurring with short intervals of a few minutes or with larger intervals of an hour or two. In those cases presenting with- out exposure of the pulp the inflammation runs a rapid course, and the vitality of the pulp may be destroyed in a few hours from venous conges- tion, terminating in complete stasis, induced by j)ressure upon the arteries entering the apical foramen. In those presenting exi^osure of the pulp, the inflammatory symj)toms may be prolonged for several days, and finally end in complete stasis and death en masse by the same mechanic obstruc- tion to the circulation, or the inflammatory symptoms may assume a chronic form and be prolonged indefinitely. Exercise or the recumbent position increases the violence of the pain in the acute form of inflammation, as does also excessive changes in the temperature, pressure from foreign sub- stances in the cavity, or the irritation from sweets, acids, or salt. In those cases where there is no exposure of the pulp the symx^toms are usually most severe but brief in their duration, and they are much less liable to suppuration or decomi^osition by reason of the exclusion of the micro-organisms from external sources. On the other hand, in those cases presenting an exposure of the pulp, the symptoms are generally less severe, but are more prolonged, the course of the inflammation being modified by the opportunity for expansion and protrusion of a portion of the x>ulp — hernia — under the pressure of the distended blood-vessels, which is made possible by the break in the con- tinuity of the walls of the pulp- chamber. The exposure of the pulp to the influence of the sei3tic conditions of the carious cavity and of the secretions of the mouth introduces a complication which renders any attempt at conservative treatment much more diflicult than would be the case if micro-organisms from external sources had not come in contact with it. The break in the continuity of the walls of the pulp-chamber causes another complication which often greatly aggravates the suffering endured in acute inflammation by permitting the pulp, which is often greatly distended with blood, to press upon the sharp and irregular edges of the perforation, producing shxingulated hernia of the puli?. Eelief is only obtained after depleting the organ by puncturing or scarifying its surface. Prognosis. — The prognosis of acute pulpitis has generally been con- sidered as extremely problematic, and therefore efforts at conservation of the organ under such conditions have never received much suijport from the profession at large. That the dental pulp may under the favorable circumstances of good general health and hygienic surroundings finally recover from acute inflammation which has not progressed to the stage of suppuration there is not the least doubt, as can be attested by numerous cases and the clinical exx^erience of many operators. And yet the fact 406 OPERATIVE DENTISTRY. remains that in many of these seeming cases of recovery supplementary pathologic changes have occurred, usually of a degenerative type, like calcareous deposits or fatty metamorphosis, which have finally, after months, or perhaps years, terminated in devitalization and decomposition, or dry gangrene. Treatment. — The treatment of acute pulpitis may be both local and systemic. As a rule, however, local treatment will usually be sufficient to control the symptoms, but when these measures fail, as occasionally hap- pens, systemic treatment may prove of inestimable value. Local treatment consists in first freeing the carious cavity from all foreign substances and irrigating it with an alkaline solution, like soda bicarbonate, one drachm, tepid water, one fluidounce, to neutralize the acid condition of the disorganized dentin. The cavity is then dried and the same local meas- ures employed as indicated in the treatment of hypersemia of the pulp. The most efficient means which can be emj^loyed to give relief in those cases complicated with exposure of the pulp is depletion by direct puncture or incision of the exposed organ. Cocaine hydrochlorate — ten to twenty- five per cent, solution — should be applied to the pulp after adjusting a rubber dam, and in from two to five minutes the iduIx) will have been suffi- ciently anaesthetized upon the surface to permit of its puncture or incision without pain. Chloretone solution, made by mixing equal parts by weight of ether and chloretone, may be applied to the exposed pulp upon a pledget of cotton for the same purpose. After the vessels have been de- pleted the pulp may be dressed with some efficient sedative and antiseptic remedy like the following : morphine sulphate, one-tenth grain, atroiDine, one-hundredth grain, dissolved in a drop of oil of cloves. The hypodermic tablets of morphine and atropine in these proportions can always be pro- cured and kept on hand ready for use, and may be prepared for applica- tion to the cavity by first crushing the tablet upon a glass or porcelain mixing-slab and then adding a drop of oil of cloves. It is then gathered upon a pledget of cotton, placed in the bottom of the cavity, and sealed in with zinc oxyphosphate, mixed thin, and inserted in this condition, so that no pressure will be brought to bear upon the exposed pulp. Tempo- rary stoppings which permit the percolation of the septic oral secretions through or around them should be avoided, as success in the treatment of these cases will depend largely upon maintaining aseptic conditions of the cavity and the pulp. Another efficient remedy for relieving the pain in acute pulpitis is a x>aste made of cocaine hydrochlorate in glycerol, ap- plied as above. Saturated solutions of menthol and thymol are also recommended for the same purpose. Another method of relieving the congested condition of the pulp is the abstraction of blood from the engorged veins and cax)illaries of the gums, directly over the affected tooth, by scarification, and promoting the flow of blood by the application of warm water held in the mouth. The ab- straction of blood by the application of leeches is an old method, and still advocated by some authorities. The dangers from infection, however, are so great from the use of this method that its application is inexcusable in these days of enlightened aseptic surgery. INFLAMMATION OF THE DENTAL PULP. 407 Counterirritation is sometimes useful in relieving the congestion of tlie vessels of the pulp by drawing the blood to the surface. This may be accomplished by the continued use of capsicum plasters applied to the gum over the affected tooth ; painting the gum with tincture of aconite and tincture of iodine, equal parts, or by drying the gum and painting it with cantharidal collodion, which raises a blister. Care should be taken to paint only a small area, as the irritation induced by the blister renders the gum very sensitive for several days. Systemic treatment consists of the administration of general sedative and analgesic remedies. Ten grains of Dover's jjowder administered at bed- time, or five to ten grains of antikamnia, or ten grains of ammonol, will usually insure a quiet night. A hot foot-bath just before retiring may be supplemented with advantage, as this is a useful means of equalizing the circulation and relieving arterial tension in the upper portion of the body. A brisk saline cathartic is also a valuable additional means of relieving the determination of the blood to the affected part. After the inflammatory symptoms have been relieved and the pulp becomes quiescent, the question of the after-treatment must be settled, — viz., whether conservation shall be attempted or the pulp devitalized. The settlement of this question calls for a clear insight into the local and con- stitutional conditions which surround the case, and good judgment is required in the final decision, for if the operator would render his patient the best possible service in each individual case he must be free from all bias or prejudice and ready to act as his best judgment dictates. ■ SUPPURATION OF THE DENTAL PULP. Definition. — The term suppuration comes from the Latin suppuratio, from suppurare, to form pus. The formation of pus. Suppuration is the most frequent termination of acute inflammation. An inflammation which terminates in this manner is termed suppurative inflammation. Suppuration is a process by which the morphologic elements found in the inflammatory exudates— the leucocytes and the embryonic cells formed from the fixed tissue-cells — are converted into pus- corpuscles and the in- tercellular substance of the tissue is liquefied. The conversion of the leucocytes and embryonic cells and the liquefac- tion of the intercellular substance to form pus are i)roduced by a peculiar peptonizing or digestive action of the pyogenic micro-organisms. The causes of suppuration may be divided into indirect and direct. The indirect causes of suppuration are the inflammatory phenomena of exudation, the crowding of the connective- tissue sj^aces with the corpus- cular elements of the blood, and the consequent pressure uj)on the capillary blood-vessels, resulting in complete stasis and death of the tissues invoh-ed. Death of the tissues, however, is not always necessary to produce suppu- ration, but the changes which take place in the affected parts are those which are expected to follow intense irritation, — viz., hypertemia, exuda- tion, coagulation of the fibrinous elements, and partial stasis. The direct caiises of suppuration are certain specific micro-organisms — 408 OPERATIVE DENTISTRY. the pyogenic bacteria — and tlieir peptonizing effect upon the leucocytes^ embryonic cells, and intercellular substance of the tissues. In the suppuration due to the presence of the pyogenic bacteria — in- fectious inflammations — the direct cause which produces it multiplies in the tissues. Consequently its tendency is to become progressive, while from the pus produced by this form of inflammation the pathogenic micro- organisms — the staphylococci and streptococci — can be cultivated, and if in- troduced into another organism will produce inflammation and suppuration. Pus may be j)roduced, however, under certain circumstances without the presence, aid, or intervention of micro-organisms, as, for instance, by the introduction beneath the skin of certain irritating chemical sub- stances. Councilman was the first to prove the fact that croton oil when injected beneath the skin of rabbits would produce suppuration without the action of micro-organisms. The early experiments in this line gave very conflicting results. Some investigators succeeded in producing an aseptic pus which would not cause suppuration when introduced into another organism, while others produced a septic product with the same chemic agent. These conflicting results were due in some cases to imper- fect aseptic methods ; in others to the fact that the same chemic substance would produce suppuration in one species of animal and not in another, as pointed out by Christmas, who was unable to produce suppuration in rabbits with turpentine or mercury, but succeeded with dogs. Fig. 502. Suppuration of the dental pulp is in nowise different from suppuration as observed in other connective tissues, except that which relates to its loca- tion and peculiar environment. It is found most commonly associated with exposure of this organ and under large fillings, the pulp of the tooth having been previously inflamed. INFLAMMATION OF THE DENTAL PULP. 409 Fig. I'll mm mm 503. Supi)uration of the pulp presents in two forms, superficial and paren- chymatous, and may be either acute or chronic in its manifestations. Acute superficial suppuration of the pulp, or ulceration, is a destructive loss or solution of continuity of the exposed surface of the organ ; a molec- ular death of tissue, which will not permit of repair by xDrimary union, and owes its existence to the fact that the retrograde changes or metamor- phoses are in excess of those of repair. Change the relationshijp between these conditions and the ulceration will heal by granulation, just as is seen in ulcerations upon the free surfaces of the body. If unchecked, the ulcerative process tends to gradual but final destruction of the whole organ. Fig. 502 shows a section by Black taken from an inflamed area. The blood-vessels are represented as empty to bring them more prominently into view, but in reality they are filled with coagulated blood. It will be further noticed that the normal cells have nearly all disappeared, and that their places have been occupied by the in- flammatory products of exudation. Opposite the point of exposure (a) the odontoblastic layer has been destroyed and a pus-pocket formed in the deeper substance of the pulp, while at h the odontoblastic layer has been consider- ably undermined. This undermining of the odontoblastic layer Dr. Black found to be the general rule in progressive suxDpuration or ulceration of the pulp. Fig. 503 represents a longitudinal section taken from a case of pro- gressive suppuration or ulceration of the pulp of an incisor, and shows that the destructive process follows the course of the veins, progressively de- stroying the tissue as it advances from the iDoint of exposure to the apex. Acute parenchymatous suppuration of the pulp, or abscess, is an accumula- tion of pus in the parenchyma of the organ surrounded by a wall of lymph. It owes its existence to the action of an excessive and continuous irritation which has caused a copious exudation, the filling of the connective- tissue spaces, pressure upon the capillary blood-vessels causing stasis, followed by coagulation of the fibrinous ele ments. The leucocytes lose their vitality, while pressure upon the con^ Progressive suppuration of tlie pulp. (After Black.) X 100. a, healthy tissue ; 6, odonto- blastic layer ; c, inflamed tissue showing di- lated veins ; d, line of demarcation of suppu- rative process ; e, pus. 410 OPERATIVE DEXTLSTRY. necti^-e-tissue cells involved in the affected area produces a like result in them, and by the action of the pyogenic bacteria which have gained access through external channels, or through the avenue of the circulation, the exudates and the tissues are converted into pus. These abscesses are usu- ally situated near the point of exposure, and are rarely found singly. Black says it is not uncommon to find several minute pus-pockets at a little distance from the point of exposure. The abscess may, however, occupy the central portion of the pulp. Burchard removed such a pulp, the abscess involving nearly its entire structure, but leaving the peripheral portion unbroken, as shown in Fig. 504. Fig. 504. Transverse section of pulp of inferior bicuspid, partly diagrammatic. (After Burchard.) a, abscess cavity ; 6, embryonic cells at periphery of abscess cavity ; c, occluded blood-vessels. Black has found abscesses in the deeper structures of the pulp, most frequently in the molars. Fig. 505 shows such an abscess in a central in- cisor, about midway of its length, the coronal portion of which was sup- purating, while the evidences of inflammation within the deeper structures was rather more extended than is common. Suppurative inflammation of the pulp under capiDings and large fillings used to be a frequent occurrence before the introduction of antiseptics in the treatment of surgical wounds. To-day, however, such occurrences are much more rare by reason of the improved methods of treatment which have been based upon this great scientific discovery. Symptoms and Diagnosis. — The formation of an abscess in the soft tissues of the body causes considerable swelling, and when the swelling is hindered by overlying and unyielding fascia the pain becomes very intense, and the pus burrows along courses which offer the least resistance, often forming long and tortuous channels in the effort to reach a point of exit. In suppuration of the pulp with a minute i)erforation of the wall of the pulp-chamber, or under a capping or a large filling, the pus is held back, and as it accumulates, causes pressure upon the tissues of the pulp, which INFLAMMATION OF THE DENTAL PULP. 411 either give way or are destroyed. The pain which is induced by this pro- cess is different from that caused by hypersemia, in that the onset of the attack is not so sudden nor so violent. It begins with a dull, heavy, gnaw- ing sensation, which gradually increases in intensity to the most violent and almost unendurable pain. The duration of the pain is governed by the amount and rapidity with which the pus is formed. Sometimes the accumulation of the pus is so rapid that the vitality of the pulp is destroyed in a few liours ; at others devitalization may not occur under twenty-four to forty-eight hours. Death of the pulp is induced by the pressure upon the apical blood-vessels, causing general infarction. Evacuation of the Fig. 505. The field includes about one-half of Abscess within the tissues of the pulp. (After Black.) X 250. the little pocliet of pus. pus by opening the pulp-chamber gives almost instant relief from the severe symptoms. Sometimes when the pus is deep-seated it becomes necessary to puncture the abscess with a probe. The amount of pus which is occasionally contained in a pulp-chamber is surprisingly large, at times welling up in such quantity as to nearly fill a large cavity of decay. The pressure under such circumstances must have been very considerable in- deed, and thus accounts for the intense character of the pain. In from six to twenty-four hours after the cessation of the pain symptoms of apical irritation begin to be manifest unless the pulp-chamber has been opened and the pus is evacuated. The presence of small abscesses within the parenchyma of the pulp are not always productive of severe pain, and they may be retained for an indefinite period, and finally absorbed. (Black.) Accumulations of pus within the pulp may, as in other locations of the body, undergo fatty degeneration, as pointed out by Salter. Decomposi- tion of the retained pus may take place with the generation of mephitic gases. Black says upon this point, ' ' Warm liquids when taken into the mouth should increase the pain by expanding the gases, while cold would relieve it by the opposite effect." This is a diagnostic fact of considerable 412 OPERATIVE DENTISTRY. importance, and should always be borne in mind in diagnosing the various forms of acute pulpitis. Treatment. — The treatment of this class of cases requires the im- mediate opening of the pulp-chamber, the evacuation of the pus, and anti- septic treatment of the suppurating pulp. Although it is possible under favorable circumstances to control the suppurative process and relieve the inflammatory symptoms, efforts at conservation of the pulp are not favor- able, for the reason that they so rarely succeed. It is, therefore, the wiser plan to devitalize the pulp and remove it as soon as the inflammatory symptoms are under control. CHEONIC INFLAMMATION OF THE DENTAL PULP. Chronic pulpitis is usually a sequel of the acute form of inflammation, but it may occasionally be due to a low grade of irritation which has never been of sutflcient severity to produce other than a mild but continuous hypersemia of its blood-vessels, such an irritation as would accompany the gradual wearing down of the teeth from mechanic abrasion or chemic erosion with the formation of secondary deposits, as already pointed out in Chapter XXII. Chronic pulpitis, which is the sequel of the acute stage, may present itself in either of three common forms, — viz., chronic suppurative inflamma- tion, hypertrophic inflammation, and degenerative inflammation. Chronic suppurative inflammation of the pulp is almost always confined to the surface of the pulp in connection with perforations of the wall of the puli3-chamber, which are small or moderate in extent, but which allow of the free escape of the pus as rapidly as it forms. If for any reason the accumulations of pus are retained, active symptoms usually supervene, and acute abscess of the pulp is the result. Chronic suppuration of the pulp tends sooner or later to cause its de- struction either by molecular death (ulceration) and devitalization of its tissue, or by death en masse (gangrene) of extensive portions and sloughing of the gangrenous areas. Severe pain is rarely present in this form of in- flammation, unless the opening into the pulp -chamber becomes stopped up with food debris, or the cavity is filled with a septic dressing. The removal of these obstructions to the escape of the pus gives immediate relief. The heat sense is greatly lessened, as is also its general sensitiveness to chemic irritants and to pressure or instrumentation. The only reliable treatment in this form of inflammation of the pulp is devitalization and extirpation. Conservative treatment based upon the possibility of the suppurating surface becoming cicatrized and the pulp being capable afterwards of performing its normal functions rests upon such meagre clinical evidence that it cannot be recommended except as a purely experimental study. Sypertrophic inflammation, or polyj)us of the i^ulp, can occur only when the walls of the X3ulp-chamber have been perforated to a considerable extent, for when they are intact there is no ijossibility of enlargement, by reason of the fact that there is no room in the pulp-chamber for such growth. The size of the perforation in the walls of the pulp-chamber determines INFLAMMATION OF THE DENTAL PULP. 413 to a certain extent the size and the character of the new growth. In small perforations the pulp protrudes but slightly, except when acute inflam- matory symptoms are present, as already indicated upon a previous page. When the perforation in the wall of the pulp-chamber is large, the pulp may bulge from the opening, forming a large fleshy mass {polypus ofthepidp'), which may be so large as to fill the entire cavity of decay, and even pro- trude beyond it. This condition is more commonly seen in young persons at the period of adolescence and in scrofulous and tuberculous individuals. In the early stages of the growth or hypertrophy of this tissue it is very sensitive, but later, as it increases in size, it gradually becomes less and less sensitive until, comparatively, it is no more sensitive than the gum-tissue. The hypertrophied mass is composed of vascular distentions, granula- tion-tissue, and connective-tissue fibres, the whole mass being covered with a thick epithelium. In general appearance it is so like gum-tissue that it is with extreme difficulty that it can be distinguished clinically from that tissue. It may be difi'erentiated from a gum festoon which has grown into the cavity of decay by the fact that it is connected to the pulp by a narrow constricted pedicle, and that a probe can be made to pass beneath it and completely around the whole circumference of the cavity of decay, while a gum festoon which occupies the cavity can be lifted out, and will be found to be connected with the gum at the cervical margin by a broad pedicle. Hypertrophied tissue will be found to be quite difiicult to destroy with arsenic or other escharotics. Before attempting devitalization the mass should be amputated at the bottom of the cavity by severing the narrow pedicle, and as soon as hemorrhage has ceased arsenic may be applied to the stump and the case treated as an ordinary exposure. Calcification of an hypertrophied pulp has been known to occur. Tomes * mentions a case reported by Eogers, in which hypertrophy of a pulp took place after the crown of an upper molar tooth was removed in an unsuccessful attempt to extract it, leaving the pulp exposed. Some months afterwards the roots were removed, and the hypertroj)hied pulp was found to have extended over the sharp edges of the pulp-chamber and to be completely calcified. Black f described a somewhat similar case occur- ring under a metallic capping, and Heider and Wedl | figure a case in their atlas of a similar condition occurring in an incisor tooth of an antelope. Another result of hypertrophic inflammation of the i^ulp is the re- sorption of the dentin surrounding the pulp, causing enlargement of the pulp-chamber. Such conditions are, however, very rarely met with in clinical practice. Black mentions a case of this character occurring in a first lower molar which he had capped for exposed pulp ten years before and had inserted a large gold filling. Irritation of the pulp had persisted for the last two or three years. On removing the filling the pulp-chamber was found to be enormously enlarged, and an opening to the peridental membrane had occurred at the bifurcation of the roots. * Tomes' s Dental Surgery, 4th ed., p. 367. t American System of Dentistry, vol. i. p. 859. X Atlas of Pathology of the Teeth. 414 OPERATIVE DENTISTRY. In another case, a central incisor, the enlargement of the pnlp-chamber was not so great, but was unmistakable. The writer saw a similar case in consultation with the late Dr. W. W. Allport, occurring in a first superior bicuspid, the pulp of which, accord- FiG. 506. Fig. 507. Pulpitis. ( After Bodecker.) y 300. S, second- ary dentin ; B, bay-like excavations filled with medullary or inflammatory corpuscles ; M, mul- tinuelear body ; V, blood-vessels in transverse section. ing to the record, was not exposed when the tooth had been filled five years before, but which was found upon removing the filling not only ex- posed, but the pulp -chamber was en- larged to more than twice its normal size. This case occurred in a lady aged about forty, who had been suffer- ing for more than a year with reflex neuralgia and dimness of vision which threatened blindness. Fig. 506 is made from a jDhotograph of a superior central incisor in the pri- vate collection of the writer, and shows the pulp-chamber greatly enlarged. Bodecker * presents a figure illustrating the resorption of secondary dentin (Fig. 507), which seems to indicate the manner in which resorption of the dentin forming the walls of the pulp-chamber takes place in this class of cases. At M will be noted a large multinucleated cell (giant cell) which has invaded the area of resorption and is evidently performing the function of the odontoclasts by removing the dentin. Degenerative inflammation of the pulp, involving structural changes in the tissues, is usually caused by a long-continued and low form of inflamma- tion, such as would be likely to be produced by a pseudo- or by an incom- plete exposure of the pulp, or by a pulp -capping. The most common form of degeneration of structure is atrophy of all the normal elements of the pulp except its fibrous tissue, which becomes greatly increased in amount, forming areola which are filled with fluid. (Black.) The changes in the structure usually take place at or near the point of exposure, but they are not always confined to this location. The bulb of the j)ulx3 suffers most, while the balance of the organ may appear to be in a more or less normal condition. Fig. 508 illustrates this condition, and was made from the bul- bous end of the pulp of a tooth which was the subject oi pyorrhoea alveolaris. Morphology and Histology of the Dental Tissues, p. 645. INFLAMMATION OF THE DENTAL PULP. 415 Black* says of this affection, "The original cells of the pulp for the most part disappear or lose their nuclei and become converted into very- fine fibres. Areola develop in the matrix, and all the histologic characters of the tissue are profoundly changed." Fig. 508. jfes^ Section of dental pulp. Bulbous end. Fibrous degeneration. (V.A.Latham.) X 50 Arkovy has described this affection as reticular atrophy of the pulp. Black found in his studies of this condition every possible grade of change, from an occasional appearance of areolse to complete areolation of large portions of the pulp. He thinks it is possible that the oedema noticed in the affection may be the result of hypersemia which has produced effusion, and yet in all the cases examined he found the evidences of inflammatory action unmistakable. The symptomatology is not well marked, although the sensitivity of the organ is greatly diminished to all the tests applied. Treatment. — The only treatment that can be recommended is devi- talization of the pulp and its extirpation. American Sj^stem of Dentistry, vol. i. p. 859. CHAPTEE XXV. EXPOSURE OF THE DENTAL PULP AND ITS TREATMENT. Exposures of the dental pulp are either the result of caries or of trau- matic injuries of an accidental nature which produce a loss of tissue by fracture, thus uncovering the pulp, or as a result of surgical injury in the preparation of the cavity to receive a filling. Deep-seated caries is the most common cause of exposure of the pulp. By the processes of decalcification and disintegration of the dentin it sooner or later exposes the pulp and renders it subject to painful irritation, hypersemia, inflammation, and finally devitalization. In the consideration of the subject of pulp exposure from caries and traumatic injuries it may, for the convenience of description, be divided into three stages or degrees, — viz. : Pseudo-exposure. Incomplete exposure. Complete exposure. Pseudo-exposure, or false exposure of the pulp, is that condition which prevails when the carious process has so far progressed as to have nearly reached the pulp, leaving only a thin layer of partially decalcified and infected dentin to protect it from mechanical injury, but which is, how- ever, more or less readily penetrated by the oral secretions, the bacteria of the mouth, the soluble chemic substances which enter the mouth in the form of food, condiments, and medicines, and by the influence of changes of temperature of even a moderate degree. These irritating influences often render the pulp highly sensitive, and cause it to respond verj^ acutely whenever they are brought to bear upon it through the carious cavity, while if prolonged, they end, sooner or later, in inflammation and finally death of the pulp. A traumatic injury which nearly exposes the pulp, leaving the pro- tecting surface so thin as to cause the pulp to respond painfully to the above-mentioned irritating agencies, should be classed as a pseudo- exposure. The pain which is produced by active hypersemia is generally acute and paroxysmal in character, but, as a rule, is only of a few minutes' duration. It comes on most frequently while eating, especially sweets and acid fruits, or drinking hot or very cold fluids, or breathing very cold air. If the pulp becomes infected with the i^yogenic organisms, efforts to conserve its vitality will usually prove futile. Treatment. — Two methods may be employed in the treatment of pseudo-exposure of the pulp, — viz., conservation and devitalizotioyi. Conservation. — Conservative treatment of the pulp should in these cases be employed under all circumstances which present a fair prospect of 416 EXPOSURE OF THE DENTAL PULP AND ITS TREATMENT. 417 maintaining the organ in a normal condition. The pulp being the organ which supplies nutrition and sensation to the dentin, its vitality should for these reasons be carefully preserved, while, upon the other hand, after the vitality of the pulp has been destroyed, the tooth loses its translucency, be- comes more or less discolored and brittle, presents a greater susceptibility to caries, and is liable to periodic attacks of pericemental irritation from the decomposition of the organic elements of the dentin, while occasionally the pericemental irritation may increase in severity or become chronic, resulting finally in the loss of the tooth. It therefore becomes for the latter reasons also very important that the vitality of the pulp should be preserved whenever it is possible to do so. Certain operators have, on the other hand, advocated the conservation of the pulp in all cases. Witzel advo- cates conservative treatment of even small portions of the living pulp re- maining in the canals, and Belisario and Henry advocate the same course. Devitalization should be practised only as a dernier ressort The writer is aware that this teacJiing is in opposition to some very good authorities, who have frequently stated "that when a tooth has been fully formed it has no further need of the pulp, and it may, therefore, be destroyed with- out damage to the integrity of the tooth ;" but he, nevertheless, desires in these pages to enter a protest against such teaching, and against the prac- tice of destroying by wholesale dental pulps which he believes could, with the same degree of care and skill exercised in their devitalization, have been preserved to fulfil their normal function for many years, or even for a lifetime. Opening the Cavity. — In the opening of the cavity and the excava- tion of the disintegrated dentin great care should be exercised not to expose the pulp. The relations of the pulp-chamber and of its cornua must be kept constantly in mind, and even then it may be that by an un- lucky sweep of the excavator or an excessive prolongation of the pulp cornua the pulp -chamber may be entered and the difiiculties of the con- servation of the pulp thereby greatly increased. After all of the disintegrated and decalcified tissue has been removed — and this should not be commenced, for prudential reasons, until the rubber dam has been adjusted — the cavity may be carefully wiped with an efiacient antiseptic, like the oil of cloves, oil of cassia, oil of peppermint, or carbolic acid, ninety-five per cent. The surface of the cavity lying nearest to the pulp should then be carefully scrutinized with a magnifying lens for the slightest exposure of the pulp or of its cornua, and if the integrity of the pulp-chamber is found to be intact, the pulp may be protected from pressure and thermal shock by the interposition of a rigid and non-con- ducting material — that will possess no irritating qualities — between the bottom of the cavity and the filling. Temperature Sense. — The "temperature sense," as shown by Dr. Louis Jack,* varies greatly in different individuals, and this fact must always be taken into consideration in all efforts of conservative treatment of the pulp. * Dental Cosmos, January, 1899. 27 418 OPERATIVE DENTISTRY. Dr. Jack has found tliat the variation in the heat- rate stands, in normal teeth, between 120° and 135° F., while the normal cold-rate varies between 40° and 70° F. The teeth of each person seem to possess an individual tolerance of a certain degree of heat and cold which will not produce pain, but whenever these limits are passed pain is the result. The average range of tolerance was found to vary between forty-eight and seventy-five degrees. It there- fore becomes evident that if the vitality of the pulp is to be preserved in this class of carious teeth the pulp must be thoroughly protected against any degree of temperature that might cause irritation. Dr. Jack also observed that marked intolerance to degrees of tempera- ture that are within the average normal range indicated a serious condi- tion of the pulp, and that after the pulp had been protected for a time from thermal shock, the temperature range gradually increases until normal tolerance is reached. Materials for Capping. — Gutta-percha is, perhaps, by reason of its non-conducting qualities, the very best material that can be used for the purpose of protecting the pulp against thermal shock. The cavity may be entirely filled with it, or it may be used as a simple non-conducting lining, and the balance of the cavity filled with zinc oxyj)hosphate cement. Metal fillings should never be introduced into such cavities until the normal tolerance to heat and cold have been restored. The metallic filling may be inserted after removing a portion of the gutta-percha or cement. Its entire removal and substitution of a metal filling often proves disastrous to the vitality of the pulp. Such teeth can be made, however, more comfortable by the insertion of porcelain inlays than by metallic fillings, as the porce- lain is a poorer conductor of caloric than the metals. Zinc oxy sulphate cement to which a drop or two of oil of cloves has been added is frequently used as a capping or protector of the dental pulp because of its non- irritating and non-conducting proiDerties. Whenever the layer of dentin covering the pulp is very thin and there is danger of producing pressure upon it in packing the filling, or from the pressure of mastication, a metallic cap may be employed (Fig. 509), or one may be fashioned from sheet lead or tin. The ^^' ' metal should be so concaved that when it is ^) ^ "Pl H 1|) p U placed in position in the cavity it will touch only at its edge. To protect the pulp from thermal shock and to secure the cap in position thick zinc oxysulphate may be flowed upon the bottom of the cavity, the cai) placed in this and covered with a layer of the same material or of gutta-percha stopping, — after the cement has set, — and the balance of the cavity filled with zinc oxyphos- phate. Zinc oxychloride cement is sometimes used as a pnlp capping, but the dangers of irritation and devitalization due to the irritating and escharotic action of the zinc chloride has caused it to be looked upon as an unsafe material to employ when the conservation of the pulp is the object in view. It was formerly employed to a considerable extent not only in the treatment of such cases as are now under consideration, but in cases of EXPOSURE OP THE DENTAL PULP AND ITS TREATMENT. 419 actual or complete exposure of tlie pulp, and statements were made by enthusiastic o^Derators as to its wonderful conserving effect upon the pulp ; but a few years later it was discovered that the term preserving better suited the condition which resulted from its application as a pulp capping, for nearly all the cases which had been so treated were found to be in a devitalized and mummified condition. As an obtundent of hypersensitive dentin in shallow cavities it is of great value ; but its application to deep-seated caries, or where the pulp is almost exposed, its use is to be deprecated for the reasons given above. Zinc oxyphosphate cement is employed by some operators to the exclusion of all other materials for capping the pulp in this class of cases. To pre- vent the irritation and pain which would follow its direct application to the dentin various substances are used to line the cavity, — viz., solutions of chlora-percha, varnishes, Canada balsam, and zinc sulphate. As a further protection against thermal shock the bottom of the cavity may be covered with a disk of sheet asbestos, blotting-paper, writing-paper, horn, quill, cork, vulcanite, or ivory, which may be secured in place with chlora-percha, copal varnish, or Canada balsam, and zinc oxyphosphate flowed over it. Incomplete Exposures due to Caries. — Incomplete exposure of the pulp may be described as that condition in which a single cornu or horn of the pulp is exj)osed as the result of caries or from traumatic injury. This class of exposures occurring as the result of caries, the exposure of recent origin, and in which the irritation and pain have not been mani- fested for more than twenty-four hours, are many times amenable to con- servative treatment. Exposures of this class, if caused by traumatic injury during the ex- cavation of the cavity, give better prospects of successful conservation than those produced by caries, for the reason that the latter are generally more or less infected with the pyogenic micro-organisms ; while in the traumatic cases, if treated upon surgical principles, infection can be pre- vented and the pulp maintained in a normal condition by the exclusion of the micro-organisms and other sources of irritation and protecting it from pressure. Symptoms. — Incomplete exposure of the pulp, due to caj-ies, some- times presents a history of intervals of irritation and pain, more or less severe, covering a period of a few hours or days. Finally the patient is robbed of a night's sleep by the severity of the pain, and next morning seeks professional advice. The pain is described as sharp, stinging, or burning in character, and the affected tooth is exceedingly sensitive to heat and cold, sweets and acids, or pressure of food within the cavity. Paroxysms of pain are induced by contact with any of these irritating sub- stances, while it is aggravated by vigorous exercise, by lowering the head, as in stooping to pick something from the floor, or by assuming the hori- zontal position. Exercise and the positions mentioned increase arterial tension in the head, and thus by the increased pressure of blood in the pulp, pain is induced or augmented. The pain in the early stages of irrita- tion is never very severe, but as the case progresses towards inflammation 420 OPERATIVE DENTISTRY. it becomes more and more intense, with shorter intervals of respite, until finally the pain becomes of a sharp, deep-seated, throbbing character and well-nigh continuous, which denotes a high degree of congestion. These symptoms are doubtless due, in a majority of instances, to septic infection from the pyogenic bacteria found in the oral secretions and food debris lodged in the mouth and between the teeth. With proper treatment fol- lowing antiseptic lines even a case of this character is not entirely beyond hope of successful conservation, provided, as already mentioned, these symptoms have not been manifest more than twenty-four hours. Treatment. — The treatment consists, first, of efforts to allay the pain by removing the causes of irritation and subduing the hypersemia, and secondly, of protecting the pulp against the further influence of these exciting causes of incipient inflammation. The cavity should first be carefully syringed with tepid water to which has been added a little soda bicarbonate and an antiseptic like listerine, pasteurine, or borolyptol, to remove the food debris, neutralize the acid condition, and correct to a certain degree the septic condition. Many times this procedure will relieve the severity of the pain in a few minutes, or entirely control it. The rubber dam should then be adjusted, the cavity carefully dried with bibulous paper or amadou, and the carious matter deftly removed, care being exercised not to wound the pulp, as such wound would endanger the vitality of the pulp by furnishing an open gate- way for the entrance of the pyogenic bacteria to its deeper structures. If the pulp is accidentally wounded, the bleeding point should be touched with oil of cloves or other eflicient but non-escharotic antiseptic. The walls of the cavity may now be saturated with oil of cloves, oil of cassia, or the volatile extract of eucalyptus, and the exposed cornu of the pulp protected with a metal cap or other suitable rigid covering, the con- cavity of which has been filled with a paste composed of oil of cloves and zinc oxide, or zinc oxysulphate cement. The object of the paste or the cement is twofold, — first, to furnish an antiseptic dressing for the exposed crown of the pulp, and secondly, to seal the perforation of the pulp-chamber with a non-irritating substance, which would effectually prevent any pro- trusion of the pulp beyond its normal limits. Over the cap should now be flowed a thick solution of chlora-percha or zinc oxysulphate, and after this has set the cavity may be filled with gutta-percha stopping or zinc oxyphosphate. Prognosis. — The prognosis in these cases will depend upon the local condition of the pulj) when capped, the surgical care with which the cavity has been prepared and sterilized, the dexterity with which the antiseptic dressing has been applied, the methods used to prevent pressure upon the exposed portion of the pulp, the i^rotection afforded against thermal shock by the overlying filling-material, and the constitutional condition of the patient at the time of the operation and for some months thereafter. If the inflammatory symptoms have not passed beyond the stage of hypersemia — and this may be known by the character and duration of the pain as already indicated — and the surgical and antiseptic technique has EXPOSURE OF THE DENTAL PULP AND ITS TREATMENT. 421 been carefully carried out, the prognosis will be fairly favorable, provided the health of the patient is good at the time of the operation and so con- tinues. Anaemic conditions, plethora, pregnancy, nervous debility, tuber- culosis, and syphilis are contraindications for the conservative treatment of the pulp. It must be remembered, however, that whatever form of capping is employed to conserve the vitality of the pulp, its ultimate success as an operation depends upon the formation of secondary dentin at the point of injury which shall remove the dangers of the devitalization of the pulp caused by the disease or the injury, and this cannot be assured until after the lapse of a considerable period of time, usually from one to two or three years. Although it is true that a large proportion of these cases will do well under favorable circumstances, yet it is equally true that at the end of this time a certain number will be found to have lost their vitality, even though little discomfort or none at all had been experienced. Incomplete Exposures of the Pulp due to Traumatism. — Trau- matic incomplete exposures of the pulp are usually the result of accidents during the excavation of a carious cavity, or from mechanic abrasions or chemic erosions, but occasionally it may occur from an external injury which fractures a portion of the crown and leaves one of the cornua exposed. In traumatic exposures of the pulp due to accidents in excavating, the cornu of the pulp is usually wounded, and is followed by hemorrhage and acute x)ain, which, however, soon subsides. The bleeding ]3oint may be treated as just described, or irrigated with a five per cent, warm solution of carbolic acid,— escharotics should be avoided, — and as soon as hemor- rhage has ceased the extent of the injury can be ascertained, when, if it does not extend beyond the involvement of the cornu of the pulp or a very small opening into the chamber, the excavation may be completed and the case treated by capping upon the lines already indicated. If, however, the pulp has been seriously wounded by the instrument slipping into the bul- bous portion and causing a complete exposure, devitalization is the only remedy. In exposures due to abrasions, erosions, and external traumatisms which fracture the crown, conservative treatment is out of the question, as there is no means of adequately protecting the pulp against the irritating influences which surround it. Devitalization or immediate extirpation must therefore be resorted to in order to relieve the patient of the suffer- ing incident to an exposure of this character. SECONDARY DENTIN, OR DENTIN OF REPAIR. One of the main objects sought in the conservative treatment of the exposed pulp is to stimulate nature to repair the breach made in the walls of the pulp-chamber by disease or traumatism, or to protect the pulp against a threatened breach of its walls by the interposition of a new- formed tissue laid down by the odontoblasts. In the study of the forma- tion and calcification of the dentin (Chapter II.) it has been shown that the 422 OPERATIVE DENTISTRY. chief function of the odontoblasts, which are arranged in a continuous layer over the entire periphery of the pulp, was that of forming or build- ing the dentin, and that upon the completion of the formative process the function ceased. The function, however, of the formative cells is not lost, for it fre- quently happens that under the stimulation of irritation occurring at any period of life, produced by mechanic abrasion, chemic erosion, caries, and other forms of external irritation, the odontoblasts again become active and deposit calcific material within the dentinal tubuli, termed tubular calcification, or lay down at the point of irritation a x)eculiar calcific mate- rial, termed secondary dentin, the dentin of repair of Salter, in a seeming effort to build a barrier against the encroachment of the disease or injury upon the territory of the pulp (Fig. 510). These deposits are always found opj)Osite, or rather at the base of, the dentinal fibrillse involved in the irritation. Calcific material is also laid down by the odontoblasts in tem- porary teeth retained beyond their normal period, and as a senile condition in the teeth of elderly people (Fig. 511), the pulp-chamber and canal being sometimes almost obliterated by this process. Secondary dentin has sometimes a very close resemblance to normal dentin, but it is by no means a perfect example of this structure. In the new formation as found in i^ersistent temporary teeth, in the senile' calcifi- cation of elderly persons, and in cases of chronic irritation, the new-formed tissue often approaches the perfection in structure of normal dentin, while in those cases which are dependent upon some form of external irritation like mechanic abrasion, chemic erosion, or caries, the new-formed tissue which has been developed to shield the pulp against these irritating influ- ences often presents a low grade of structural organization, the tubules being scanty, very irregular in their course, and the tissues more dense than normal dentin, while occasionally it will be almost structureless. Dr. Black* is of the opinion that the formation of secondary deposits within the pulp-chamber, in cases of exposed pulps which have been capped, do not permanently conserve the vitalitj^ or the health of the pulj), but that they usually produce exhaustion, degeneration, and finally death of the organ. He looks upon those cases of capping as the most hopeful which have passed on for years without the formation of any deposit whatever, very many of which seem to remain indefinitely in a perfectly healthy con- dition. Dr. Truman f says new formations are usually expected from capping pulps ; but this expectation is rarely i-ealized, as here the irritation is excessive and becomes a destructive force. Complete exposure of the pulp is that condition in which the inva- sion of caries has penetrated the pulp-chamber and laid bare, to a greater or less extent, the body or bulbous portion of the pulp, or a traumatic injury has caused the loss of a sufficient amount of the crown to open the pulp-chamber and expose its vital contents. Complete exposures of the * American System of Dentistry. t Ibid. Secondarj- dentin ;Cnamel Dentin Fig. 510.— Vertical section of human cuspid, showing formation of secondary dentin in the coronal portion of the pulp-chamber as a result of loss of tissue at the morsal edge. ;< 100. j^namel Secondary dentin Dentin Fig. 511.— Vertical section of human central incisor, showing formation of secondary dentin in the EXPOSURE OF THE DENTAL PULP AND ITS TREATMENT. 423 pulp, due to caries, are rarely amenable to conservative treatment by- reason of the inflammatory symptoms which are always present. These symptoms may be acute or chronic in their character. When the symptoms are acute and the opening into the pulp-chamber is small, so that the pulp is confined within the pulp-chamber, the swelling which takes i)lace causes pressure upon the blood-vessels, which results in stasis, general infarction, and death, — gangrene of the organ. If, on the other hand, the opening into the pulp-chamber is large, so that the pulp in swelling finds relief from the pressure by a portion of its congested tissue escaping through the opening into the cavity of decay, stasis and infarction are sometimes avoided, and the inflammatory symptoms assume a low form or chronic type. In either case devitalization of the pulp is the only satisfactory method to pursue, as eflbrts to conserve its vitality usually prove futile. Traumatic exposures of a like character are likewise not amenable to con- servative treatment, and in all such cases the pulp should be extirpated by the immediate method under local or general anaesthesia. DEVITALIZATION AND EXTIRPATION OF THE PULP. Three general methods are emj)loyed for the devitalization and extirpa- tion of the dental pulp : first, by the cliemic action of drugs ; second, by instrumentation ; and third, by local or general ancesthesia. The drugs which have been used for devitalizing the pulp by means of their chemic action are arsenous acid, zinc chloride, cobalt (arsenical ore), caustic potassa, and chromic acid. The requirements of a devitalizing agent are, — 1. That it act painlessly. 2. That it destroy vitality promptly. 3. That the action of the drug shall not produce discoloration of the dentin. Devitalization of the pulp is generally accomplished by the application of arsenous acid (arsenic trioxide), which destroys the vitality of the organ en masse. No other remedy used for this purpose possesses the above requirements in so large a degree, or is so prompt, certain, and complete in its devitalizing effect upon the dental pulp ; and yet, as the result of accident or in careless hands, it is capable of doing great damage to the surrounding tissues, and on this account some oi)erators who have wit- nessed its destructive effects upon the gingival tissues and the alveolar processes have discarded its use altogether. It still, however, remains the ^'sheet-anchor" of the profession for this purpose despite the ill effects which sometimes follow its use. Arsenic trioxide was first introduced for the purpose of devitalizing the dental pulp by Si30oner (1836), and when employed with proper care there is no remedy which gives such universally good results. Arsenic trioxide is usually combined with acetate of morphine in various propor- tions, and creosote, carbolic acid, and oil of cloves, or other essential oil, added to form a creamy paste. The earliest combination of this character was the formula of Dr. J^ D. White (1855) : 424 OPERATIVE DENTISTRY. R Arsenous acid, Morphiai sulph., iia gr. x to xv ; Carbolic acid, q. s. ft. paste. A later formula is that of Dr. J. Foster Flagg (1877) : R Arsenous acid, gr. v ; Morphise acetas, gr. x ; 01. caryophylli, q. s. ft. paste. A more recent combination substitutes cocaine hydroclorate for the morphine : R Arsenous acid, gr. x ; Cocainse hydrochl., gr. xx ; 01. cinnamomi, q. s. ft. paste. Miller (1894) recommended the following formula as possessing advan- tages over those containing morphine, as the thymol which is substituted for the morphine exceeds it in its local anaesthetic action, and has the decided advantage of possessing a considerable antiseptic quality : R Thymol, Arsenous acid, aii gr. x ; 01. caryophylli, q. s. ft. paste. Morphine. — The object in adding this drug to the paste is to utilize its narcotic properties to relieve the severity of the pain, which is often induced by the irritating effect of the arsenic upon the tissues of the pulp. Carbolic acid (deliquesced crystals) is a notable escharotic, while it also possesses antiseptic and local anaesthetic or analgesic properties, which make it a valuable ingredient of a devitalizing paste. Carbolic acid alone is capable of devitalizing the pulp. Creosote is not so vigorous an escharotic as carbolic acid, while it pos- sesses about the same degree of antiseptic and local anaesthetic power. Oil of cloves is but very slightly escharotic, while its antiseptic and local obtunding effect is very considerable. Cocaine liydrocMorate is substituted for the morphine because it possesses such strong local anaesthetic powers. Oil of ciimamon is added for its antiseptic qualities. Thymol is used for its local anaesthetic and antiseptic action. Chloretone is also used for its local anaesthetic effects, and is preferred by some operators to cocaine, as it is non-poisonous. (See chapter on anaes- thesia. ) PHYSICAL EFFECTS OF ARSENIC UPON THE PULP. The application of arsenic trioxide to the living pulp produces certain definite phenomena which are irritative in their character, and represent the earlier physical phenomena of acute inflammation, — viz., arterial hyperaemia, pain, increasing from a low grumbling, gnawing character to acute, violent paroxysms, followed by acute congestion of the blood-ves- sels, exudation, and finally apical strangulation, or general infarction, EXPOSURE OF THE DENTAL PULP AND ITS TREATMENT. 425 which effectually prevents egress or ingress of the blood-stream, causing complete stasis and death of the organ. Fig. 512 is made from a section of a pulp which had been treated with arsenic, and shows the congestion and enlargement of the blood-vessels. Fig. 512. Section of dental pulp. Blood-vessels congested from application of arsenic. Flagg* describes the phenomena as follows : '' A minute portion of the arsenic being introduced into the circulation of the pulp acts as a dy- namic, vital irritant, which causes, first^ a determination of blood to the organ, resulting, in from fifteen to twenty minutes, in uneasiness and throb- bing pain ; secondly, congestion, which causes a cessation of the throbbing character of the pain ; thirdly^ usually, complete cessation of pain, leaving like the going down of a wave ; this condition has a varied length of dura- tion, dependent upon the extent and frequency of the previous pulp irri- tation, extent of pulp exi)osure, temperamental impressibility, — nervous irritability, — systemic ability to resist and react, — vital resistance, — and such like considerations. The death of the pulp en masse being due to strangu- lation of the vessels at the apex in consequence of the congestion." Animal tissue when thoroughly impregnated with arsenic trioxide, even in small amount, is rendered proof against putrefaction, but dental pulps which have been devitalized by this drug are only very exceptionally ren- dered proof against the putrefactive process. Arsenic in large quantity, locally applied, is an energetic and powerful escharotic or caustic, but its action is somewhat slow as compared with carbolic acid, zinc chloride, caustic potassa, and chromic acid. Its escharotic effect is more marked and rapid upon tissues of low vitality — abnormal growths — than upon normal tissue. Absorption, however, takes place much more rapidly in healthy * J. Foster Flagg, Dental Cosmos, July, 1877. 426 OPERATIVE DENTISTRY. than in highly inflamed or dead tissue. This fact explains why, in com- paratively healthy puli)s, devitalization with arsenic is so much more rapid and effective than in those which are inflamed, partially calcified, or other- wise diseased. In the former a single application is usually all that is necessary to eflect complete devitalization, while in the latter two, three, and even four applications are sometimes required. Arsenic when used in large quantities ui^on an extensive surface, as in the treatment of cayicer of the breast and lupus in which the application has been intentionally permitted to include surrounding healthy tissue, absorp- tion of the drug by the healthy tissue may take place — before its devital- izing action renders the tissue incapable of conveying it to the circula- tion — in such quantities as to x^roduce constitutional effects or endanger life. That such a condition could be possible as a result of pulp-devital- ization seems beyond the possibilities of peradventure, while, upon the other hand, irritation of the apical space or the tissues beyond, resulting from the application of an arsenical dressing to a vital pulp in other than deciduous teeth, and in the permanent teeth of young children before the completion of calcification of the roots in which the foramina are very large, could only occur, if intelligently used, as a rare and accidental circumstance. The violent irritating action of arsenic when coming in contact with the surface of the pulp immediately causes arterial hyperaemia, while the devitalizing effect produced upon the tissue lying in immediate contact with it renders the devitalized tissue incapable of absorbing the drug, and thus prevents it being carried into the circulation except in an infinitesimal quantity, too small to provoke irritative inflammation at the apical space. Flagg,* in experiments instituted by him to ascertain the amount of arsenic absorbed by the pulp, found it ' ' almost incomprehensively minute, never more than one millionth (!) of a grain." He further maintains that the apical irritation which often follows upon the fourth to the seventh day after arsenical devitalization is not due to the effects of arsenic which has passed to the apical foramen, but to inflammatory conditions extend- ing to the apical portion of the pulp, and are the last stages of the process of devitalization, as may be readily shown by microscopic examination of the apical extremity of a pulp removed at this time, and which is further proved by the subsidence of the pericemental symptoms in a few hourSj or at most in twenty-four to forty-eight hours. Arkovy presented an elaborate study of the action of arsenic upon the dental pulp at the International Medical Congress, 1881, which may be briefly summarized as follows : arsenic trioxide (As.^03) when applied to a vital dental pulp induces : '^1. Hypersemia, partial or complete, depending upon the amount of the drug used ; expansion of the blood-vessels, with a tendency to throm- bosis and capillary embolism. "2. It does not produce coagulation of the tissue. * Dental Cosmos, July, 1877. EXPOSURE OF THE DENTAL PULP AND ITS TREATMENT. 427 "3. It seems to possess a specific influence upon the blood-corpuscles, combining with the haemoglobin to form a compound of arsen-hsemoglobin, which produces a yellowish tinge of the pulp-tissue and affects the color of the blood. "4. The drug is conveyed in substantia into the blood-channels, where it produces, besides the changes already mentioned, disintegration of their contents — granular detritus — -and shrinkage or ansemic collapse of the ves- sel walls. This being most noticeable where large doses had been used. "5. The connective-tissue fibres and the odontoblasts undergo no change, but the connective-tissue cells are increased from three to four times their normal size. "6. The effects upon the neurilemma is to somewhat increase the num- ber of its nuclei, while in the axial part granular destruction of the myelin sets in and the axis-cylinder begins in various locations to disappear ; while in others the notchy tumefaction of the axis-cylinder, usually seen only in cases of central lesion, can be plainly made out. ^'7. These alterations are found scattered throughout normal-looking tissue. "8. The pulp, in whole or in part, and the neighboring dentin and cementum, are tinged a brownish red when large doses of the drug are em- ployed. This discoloration is most marked in the pulp at the top of the bulbous portion and at the apical fourth or third." Miller in experimenting upon the tails of mice found that ''the action of the arsenic apjDcared to be somewhat accelerated when a glass ring was applied close to the root of the tail. This was done to simulate the sur- roundings of the apical vessels. In more than forty cases there was not one in which the action of the arsenic extended beyond the ring, and the action was not appreciably affected by enclosing the tails in plaster casts. The action of the arsenic is of a progressive nature, beginning at the point of application and extending gradually in each direction." Miller denies that arsenic trioxide produces escharotic effects upon the pulp like that of zinc chloride or carbolic acid, etc., and states, "The local application produces no immediate visible eff'ect whatever." Method of Application. — In the ajDplication of arsenic for the de- struction of the vital pulp certain important considerations are presented. 1. Dosage. — The amount of the drug that may be safely applied is from one-sixteenth of a grain (0.001 gramme), or from that to one-thirtieth of a grain (0.002 gramme). The writer has found, however, in his expe- rience, that one-hundredth of a grain (0.0006 gramme) was just as effective as a larger amount, provided it was permitted to remain in con- tact with the pulp for from three days to one week. The larger the dose the quicker the death, and vice versa, but the large dose is usually very painful, while the small dose will devitalize with absolutely no pain at all. The one-hundredth part of a grain is an exceedingly small quan- tity, and yet it can be approximated as readily as the one-sixteenth of a grain after the actual amount has once been weighed out and observed. The approximate amount is all that is aimed at, for no one would think it necessary to weigh out each dose to be applied. 428 ' OPERATIVE DENTISTRY. For many years the writer has not used morphine, cocaine, or other obtunding drug, except carbolic acid, in combination with arsenic for de- vitalizing the pulp, and has found it exceedingly rare that pain has been produced by the application, or that he has failed to painlessly remove the pulp at the end of a week or ten days. The exceptions have been cases in which severe irritation and hypersemia were present before the applica- tion was made. The text-books usually warn the student not to use any coagulating drug in combination with arsenic, as the coagulum X3revents the arsenic from taking effect. Clinical experience upon the part o'f the writer does not substantiate this teaching. 2. Placing the Dressing. — The cavity should first be syringed with tepid water containing an antiseptic or an alkali like soda bicarbonate. Next the rubber dam should be adjusted, — and this is wise in all cases before making an application of arsenic, — the cavity carefully dried, and the dressing, which should be composed of a piece of cotton the size of a pin-head, may be moistened with ninety-five per cent, carbolic acid, and the dry arsenic, which has been previously measured out, gathered up with the moistened dressing and then laid carefully over the point of ex- posure. A somewhat larger dose is necessary in cases of pseudo-exposure, as the drug is slow in penetrating the dentin even though completely decal- cified. 3. Sealing the Cavity. — It has been customary to seal the cavity con- taining an arsenical dressing with cotton and sandarach or with tempo- rary stopping. Neither of these materials are really suitable for the pur- pose, as the first soon gets foul and very offensive, while from swelling of the cotton fibre or compression from the force of mastication painful pressure upon the pulp is induced. The temporary stop5)ing is also liable, especially in crown cavities, to be compressed by mastication and produce painful j)ressure upon the pulp ; while both of them are open to the seri- ous objection of forming leaky stoppings, which, if employed in approxi- mal, labial, or buccal cavities extending beneath the gum, might lead to the escape of a portion of the arsenic and destruction of the soft tissues and alveolar j)rocess immediately surrounding the tooth. Zinc oxyphosphate mixed to a creamy paste and introduced so as to avoid pressure is the only safe material with which to seal a cavity containing an arsenical dressing. If this material were universallj^ used for this purpose, sloughing of the gum, necrosis of the alveolus, and loss of the tooth, as a result of the escape of the arsenic, would become, except in rare cases due to accidental causes, a bygone experience. In those cases which give evidence, by pain, of considerable hypersemia, palliative treatment should first be employed to relieve the suffering and reduce the congested state of the pulp-vessels, as by this means devitaliza- tion may be rendered more sure and at the same time nearly if not quite painless. The cavity should first be disinfected with a tepid carbolic acid solution — two per cent. — or a solution of fonnol, two to five per cent. Pormol is composed of forty volumes of formaldehyde and sixty of water. The former X3er cent, is made by adding one volume of formol to EXPOSURE OF THE DENTAL PULP AND ITS TREATMENT. 429 nineteen volumes of water, the latter by adding one volume of formol to seven volumes of water. Formol owes its value as a disinfectant to its great diffusibility in the strengths above mentioned ; it, however, possesses coagulating power. The application of formol to an exposed pulp is at first slightly painful, but this immediately passes away and the effect is eminently soothing. The pulp may now be dressed with morphine and one of the essential oils, and the cavity sealed for several days with temporary stopping or zinc oxyphosphate ; the latter being preferable from the fact that pressure is avoided and the pulp given complete protection against all external irri- tating agencies. Some operators prefer to dress the pulp with cocaine hydrochlorate and oil of cinnamon. Pulps which have been exposed for some time usually show evidences of suppuration. These cases should be treated by first removing as much as possible of the decalcified dentin around the exposure as can be done without producing much pain, and carefully syringing the cavity to remove the debris and wash away the pus. The arsenical dressing should be placed in direct contact with the pulp and sealed in by the method above described. After the arsenical dressing has been removed, it is well to follow this treatment with a dressing of tannic acid for a few days, as the tannin hardens the pulp and facilitates its removal. Dr. Harlan has recommended swabbing the cavity with the sesquioxide of iron, as this unites with the arsenic, forming an insoluble compound, and thus prevents any further action of this agent. Sesquioxide of iron (ferric hydrate, Fe2(HO)6) is made by precipitating ferric sulphate or ferric chloride by adding ammonia or sodium hydrate. The precipitate should be allowed to drain on muslin for a few minutes. The soft mass or magma should be placed in the cavity of the tooth. In local poisoning from arsenic the magma should also be placed over the inflamed gum as well as in the cavity of the tooth. Occasionally a small fragment of living pulp will be left in the apical portion of the canal, which is still very sensitive. It is better to destroy this by repeated applications of ninety-five per cent, carbolic acid than to reapply arsenic, for fear of it going beyond the apical foramen. Danger also exists of mistaking an enlarged apical foramen for a piece of vital pulp remaining in the canal. Errors of this character have been made by some of the very best and most careful practitioners. In all such cases it is better to err upon the safe side rather than to cause the loss of a tooth by a careless or mistaken diagnosis. Discoloration of the Dentin. — This condition often follows a violent congestion of the pulp, which has been caused by external irritants. The discoloration is produced by the disorganization of the blood-corpuscles and the distribution of the haemoglobin through the dentinal tubuli. Arsenic applied in large quantity for the devitalization of the pulp usually pro- duces a violent congestion, and more often results in producing discolora- tion of the dentin than when the drug is used in small quantities. It is therefore important in all cases of highly congested pulps to 430 OPERATIVE DBKTISTRY. Fig. 513. relieve this coudition by palliative treatment or local depletion before ajiplying tlie arsenic. Devitalization of the pulp with arsenic will rarely result in this un- fortunate condition if the above precautions are taken and the amount of arsenic used does not much exceed one-hundredth part of a grain. Extirpation of the Pulp. — The devitalized pulp should be removed at the end of a week or ten days after the application of the arsenical dressing, for the reason that at this time it can be done without pain or hemorrhage, as the natural process of separation or exfoliation has taken place between the dead and the living tissues at the apex of the root. If it is allowed to remain much beyond this period, pericemental irritation is likely to follow as a result of putrefactive decomposition and local septic poisoning. The removal of the dead pulp-tissue may be accomplished by first thoroughly opening the pulp-chamber with burs or excavators upon lines, which will give the most direct access, and then passing a fine barbed broach (Fig. 513) to the apex of the canal, rotating it once or twice in the same direction, and upon with- drawing it the pulp will be found entangled upon the barbs of the broach. If, however, the tissue of the pulp has been softened by decomposition and does not come away with the instrument, it must be broken up and removed by constant rotation of the broach, or fibres of cotton may be wrapped upon a plain Swiss jeweller's broach and rotated in the canal. This is the very best method of removing the remains of a pulp which has become liquefied by decomposition. The writer has sometimes adopted a method that was advo- cated in the journals several years ago (1872 or 1874) for removing pulp debris which could not be extracted with the broach, — viz., the introduction into the pulp-cavity and canals of pure pepsin dissolved in water acidulated with hydrochloric acid, 1 to 250, and carried into them by the means of fibres of cotton which had been saturated in the solution. This was sealed into the tooth with gutta-percha or zinc oxyphosphate and allowed to remain for twenty-four hours. The object of this method was to digest the remnants of the pulp and render them fluid, so that they could be washed out by irrigation or removed by absorbent cotton wound upon a broach. The result of such treatment is not only the removal of the pulp debris, but it also sweetens the canals and completely removes the odor of decomposition. If the pulp is extirpated at the end of a week or ten days after devitalization it will come away entire to the very apex of each canal, leaving these channels clean and in a fit condition to be immediately filled. ft ' y Barbed nerve- broaches. DHAPTEE XXYI. PULPLESS TEETH AND FILLING PULP- CANALS. Definition. — A tooth which contains a devitalized x^ulp is said to be dead ; a better term to designate this condition is pulpless, for the reason that the tooth cannot be correctly designated as dead so long as it main- tains a vital connection through its pericementum with the alveolus of the ' jaw ; but when this membrane has lost its vitality or has been destroyed, the tooth may then be correctly termed dead or necrosed, for it has no further vital connection with the economy. All devitalized or pulpless teeth may be classed, from the surgical stand-point, under two heads,— viz., aseptic and septic. Inasmuch as the septic cases are the most common they will be considered first. Septic pulp-canals are those which are invaded by the xDyogenic and saprophytic micro-organisms, and contain decomposing or XDutrefying tissue in greater or less quantity, food debris, the fluids of the mouth, or other material which forms a suitable soil for the growth and propagation of this class of organisms. (See Chapter V.) Devitalization of the pulp is usually the result of caries and exj)osure of this organ, followed by septic infection, inflammation, and suppuration ; consequently the great majority of the cases of jjulpless teeth which are presented for treatment are in a septic condition. Another class of septic cases are those in which the pulp of a perfectly sound tooth has lost its vitality from some traumatic injury or from embolism, but which perhaps for months or years thereafter has given no evidence of its condition except by the change in the color of the tooth. Suddenly, however, symp- toms of a septic inflammation of the pericemental membrane become un- mistakably manifest ; and as there is no external communication with the devitalized ]3ulp through a carious cavity by which the infection could have entered from the outside, it is fair to presume that the organisms which have established the suppurative process found a lodgement at the apical space, having been brought there through the avenues of the circu- lation. On the other hand, teeth of this class, when opened for the purpose of removing the dead and mummified pulp, often take on the most violent septic inflammation as the result of the admission of pathogenic organisms from the atmosphere or the fluids of the mouth. In all such cases the greatest care should be taken to prevent septic inflammation by the use of the rubber dam, and keeping the cavity through which the puliD-chamber is to be reached flooded with a strong antiseptic, like carbolic acid (ninety- five per cent.) or a sublimate solution (1 to 1000 or 1 to 500), 'so that when the pulp-chamber is opened an antiseiDtic of sufiicient strength will be carried into it to prevent the growth and propagations of the micro- organisms. Devitalized pulps which have not been infected either from external sources or through the avenues of the circulation dry up and become mummified. 431 432 OPERATIVE DENTISTRY. The sequelae of septic infection of devitalized pulps are pericementitis, dento-alveolar abscess, septiccemia, and j^yfemia. Pulpless teeth which present septic canals are rarely ever entirely free from a certain amount of pericemental irritation, which is due to the toxic effect of the ptomaines developed from the action of the micro-organisms upon the gangrenous pulp, and which has been forced into the apical space by the pressure of gases, gravity, or by instrumentation. If the organisms which have attacked the gangrenous pulp are of viru- lent type, active inflammation of the pericementum and alveolar abscess are likely to follow. The severity of the inflammatory symptoms is gov- erned in j)art by the character of the infecting organisms, and in part by the local resistance of the tissues and the diathesis of the individual. In those persons affected with tuberculosis and syphilis, either inherited or acquired, or who are suffering from general debility, diabetes, or albu- minuria, inflammation is prone to run a rapid and severe course. Aseptic pulp canals are those in which for various reasons, like persist- ent hypersemia due to caries, abrasion, or fracture, but which has not exposed the pulp, or for the purposes of grafting a crown or setting a bridge, devitalization of the pulp by the application of arsenous acid has become a necessity. The removal, under antiseptic precautions, of such pulj)S as soon as separation or sloughing has taken place at the apex leaves the canals in an aseptic condition, and no other treatment is re- quired than that of filling the canals at the same sitting and before the rubber dam is removed. The septic cases, however, often require several treatments before they are in a suitable condition to warrant the filling of the canals ; in fact, this should never be done while there is any mephitic odor emitted from the canals, or there is any pericemental soreness, as these are unmistakable evidences that septic conditions still prevail. Im- mediate root-filling of crooked septic canals is to be most strongly depre- cated, as the inevitable result is an alveolar abscess. If, however, the canals can be rendered aseptic by a single treatment, — and this is i^ossible in some cases, as, for instance, in the anterior teeth when the canals are straight and of large size, — immediate filling of the root is the only correct practice. Many practitioners make the mistake of over-treating such cases, thus keeping up an irritation which might be avoided by sterilization and immediate filling of the root-canal. Preparation and Treatment of Pulp-Canals. — In the treatment of septic pulj)-canals the object aimed at is that of so changing the condi- tions as to render them aseptic. This is accomplished by first excluding the secretions of the mouth by applying the rubber dam and maintaining absolute dryness of the field of operation in all subsequent treatments. When the treatment has once been commenced, from that time onward to the completion of the final operation the secretions of the mouth should never be allowed to again contaminate the pulp-canals. Fail- ure to observe this rule often renders the treatment of the case tedious and unsatisfactory. The application of the rubber dam as the first step in all the subsequent treatments is the only way to insure positive aseptic conditions. Fig. 514. — Superior left cen- tral incisor. Labio-lingual longitudinal section, showing pulp-canal. Fig. 51.5. — Superior right cen- tral incisor. Mesio-distal longi- tudinal section. sho\ving root- canal. Fig. 516.— Superior left lat- eral incisor. Labio-lingual longitudinal section, showing root-canal. Fig. 517. — Superior left lat- eral incisor. Mesio-distal longi- tudinal section, showing root- canal. Fig. 518.— Inferior left cen- tral incisor. Labio-lingual longitudinal section, showing root-canal. Fig. 519. — Inferior right cen- tral incisor. Mesio-distal longi- tudinal section, showing root- canal. Fig. 520.— Inferior left lat- eral incisor Labio-lingual longitudinal section, showing root-canal. Fig. 521. — Inferior right lat- eral incisor. Mesio-distal longi- tudinal section, showing root- canal. Fig. 522. — Superior right cus- pid. Labio-lingual longitudi- nal section, showing root- canal. Fig. 523. — Superior left cus- pid. Mesio-distal longitudinal section, showing root-canal. Fig. 524.— Inferior left cuspid. Labio-lingual longitudinal sec- tion, showing root-canal. Fig. 525. — Inferior right cus- pid. Mesio-distal longitudinal section, showing root-canal. Fig. 526.— Peculiarities in inferior cuspids and bicuspids. A, bifurcated inferior cuspid ; B, bifurcated canal, inferior first bicuspid ; C, bifurcated canal (middle third), inferior second bicuspid. Fig. 527.— Superior right first bicuspid. Bucco-lingual longi- tudinal section, showing bifur- cation of root and canals. Fig. 528.— Superior left first bicuspid. Base of pulp-cham- ber, showing entrance to root- canal. Fig. 529. — Superior right sec- ond bicuspid. Bucco-lingual longitudinal section, showing root-canal. Fig. 530. — Superior right sec- ond bicuspid. Base of pulp- chamber, showing entrance to root-canal. Fig. .531.— Inferior right first bicuspid. Bucco-lingual longi- tudinal section, showing root- canal. Fig. 532.— Inferior left first bicuspid. Base of pulp-cham- ber, showing entrance to root- canals. Fig. 533.— Inferior right sec- ond bicuspid. Bucco-lingual longitudinal section, showing rootrcanal. Fig. 534. — Inferior right sec- ond bicuspid. Base of pulp- chamber, showing entrance to root-canal. PULPLESS TEETH AND FILLING PULP- CANALS. 433 The second step in the treatment is to open the pulp-chamber and root- canals and remove all pulp debris. This is a simple matter in the superior incisor teeth, which have straight roots and normal canals, as shown in Figs. 514, 515, 516, and 517, which are longitudinal sections cut labio-lingually and mesio-distally. The canals of the inferior incisor teeth are more difficult to enter, by reason of the mesio-distal flattening of their roots and the corresponding narrowing of the canals. This is shown in Figs. 518, 519, 520, and 521, sections cut in the same manner as those preceding. The cuspids, both superior and inferior, when the roots are straight, are as easily entered as the superior central incisors. Figs. 522 and 523 are sections of the superior cuspids, and Figs. 521 and 525 are sections of the inferior cuspids. Fig. 526 represents some of the peculiarities met with in the inferior cuspids and bicuspids. The superior bicuspids usually offer no serious difficulties in gaining access to their canals. It must be remembered, however, that the superior first bicuspid has usually a bifurcated root and two canals, as shown in Fig. 527 ; these are sometimes very small, — the labial root being the smallest, — and for that reason some difficulty may be experienced in fol- lowing them to the apical foramen. Fig. 528 shows the location of the pulp-canals at the base of the pulp-chamber. The superior second bicuspid has generally a single root and a single canal, which is of good size, as shown in Fig. 529, but it is often flattened mesio-distally. Fig. 530 shows the form and size of the pulp-canal at the base of the pulp -chamber. The inferior bicuspids are almost invariably single-rooted teeth, having a single canal, as shown in Fig. 531, which usually gives free access to the apex. Fig. 532 shows an inferior first bicuspid having two distinct root- canals. Their position, however, is sometimes such — being curved inward — as to make it difficult to readily open the canal, except with drills carried in the right-angle hand-piece. This difficulty is more often experienced in the first bicuspid than in the second. Figs. 533 and 534 show the form of the canals in the inferior second bicuspids. The superior molars offer somewhat greater difficulties to thorough open- ing of their canals, by reason of the angles of inclination of their roots and the differences in the size of the roots and their canals. The difficul- ties of gaining access to the canals increase from tooth to tooth in a distal direction, not so much from the shape and direction of the canals as from the position of the teeth, which makes it impossible to use straight instru- ments or to gain a view of the field of operation except by the reflected image. In the superior ^rs^ and second molars the disto-buccal root is the only one which, as a rule, offers any considerable difficulty in locating and following the canal. Fig. 535 is a longitudinal section of the disto-buccal and lingual roots of a superior first molar, and Fig. 536 of a similar tooth cut so as to show the buccal roots. This canal is often so small that the finest Donaldson bristle cannot be made to enter it for more than a small fraction of the length of the root. Fig. 537 shows the size and form of these 28 434 OPERATIVE DENTISTRY. canals at the base of the pulp-chamber. The pulp-canals of the superior second molars are shown in Figs. 538, 539, and 540. The superior third molars are the most difficult to treat, but this is due more to their position than to any other reason. Fig. 544 is a longitudinal section of the mesio- buccal and lingual root of a superior third molar, and Fig. 542 of the' buccal roots of a superior third molar. Fig. 543 shows the size and form of the canals at the base of the pulp-chamber. Fig. 544, A and B, presents abnormal root-canals sometimes found in these teeth. The inferior molars when the canals are normal present no difficulties, as a rule, which are not readily overcome by a little skill and ingenuity. The difficulties, of course, are increased in operating upon the seco7id and third molars over those of the first. Fig. 545 shows the pulp-canals in a mesio-distal longitudinal section of an inferior first molar. Fig. 546 shows the size and form of the canals at the base of the pulp -chamber. It should be borne in mind that the roots of the inferior molars are con- siderably flattened mesio-distally, that the canals are constricted in the centre, and that the mesial root and its canal are usually much smaller than the distal root and canal. Fig. 547 represents a mesio-distal longitudinal section of an inferior second molar, and Fig. 548 shows the size and form of the canals at the base of the pulp-chamber. Fig. 549 represents a mesio-distal longitudinal section of an inferior left third molar, and Fig. 550 shows the size and form of the canals at the ball of the pulp-chamber. Fig. 544, 0, illustrates a not uncommon abnormality of the root-canals of an inferior third molar. The abnormalities in the number and the form of the roots and pulp- canals are so many and so varied that a separate description of them would occupy too much space in a volume of this character. The accom- panying illustrations. Figs. 554, 552, 553, 554, 555, 556, and 557, and Plate YII. , will, however, indicate the multiplicity and divergence of such abnor- malities, and will be a guide and a warning to the student that he will en- counter an uncertain number of teeth that will defy all efforts to follow their j)ulp-canals to the apex. Opening the Pulp-Chamber and Canals. — In opening the pulp- chamber and the root-canals of the teeth one general principle should be observed, — viz., to obtain access to the pulp-chamher in a direct line with the axis of the tooth. This rule holds good for any tooth in any part of the mouth. The operator should never attempt to gain access to the pulp- canals through an a-pproximal, buccal, or lingual cavity of decay without extending it to a point which would give direct access, as it is impossible to thoroughly cleanse the canals or properly fill them through cavities of de- cay in these locations unless the above rule is observed. It is better practice many times to drill an opening in that portion of the tooth which will give direct access to the pulp-canal, treating it through this opening, and filling the cavity of decay without reference to its proximity to the pulp-canal. The superior and inferior incisors and cuspids should always be opened through the lingual surface, as this gives direct access to the canal, while the canals of the bicuspids and molars, both superior and inferior, should for the same reason be opened through the centre of the morsal surface. Disto-buccal root Lingual root Fig. 535. — Superior left first molar. Bucco- lingual longitudinal section, showing root- canals. Mesio-buccal root Disto-buccal root Pig. 536. — Superior left first molar. Mesio- distal longitudinal section, showing buccal root-canals. Lingual root Mesio-buccal root I Disto-buccal root Fig. 537.— Superior left first molar. Base of pulp-chamber, showing entrance to root- canals. Lingual root Disto-buccal root Disto-buccal 11 root ^fl Mesio-buccal root Fig. 538.— Superior right second molar. Bucco-lingual longitudinal section, showing rootrcanals. Fig. 539. — Superior right second molar. Mesio-distal longitudinal section, showing buccal root-canal. lingual root Mesio-buccal root Disto-buccal root Fig. 540.— Superior left second molar. Base of puljvchamber, showing entrance to root- canals. Lingual root M( sio-buccal root Disto-buccal root Mesio-buccal root Fig. 541.— Superior left third molar. Bucco- lingual longitudinal section, showing root- canals. Fig. 542. — Superior right third molar. Mesio- distal longitudinal section, showing buccal root-canals. Disto-buccal root Mesio-buccal root Lingual root Fig. 543.— Superior right third molar. Base of pulp-chamber, showing entrance to root-canals. Fig. 544. — A, superior third molar ; B, superior third molar ; C, inferior third molar Fig. 545.— Inferior left first molar. Mesio-distal longitu- dinal section, showing root- canals. Fig. 546. — Inferior left first molar. Base of pulp-chamber, showing entrance to root^ canals. Fig. 547. — Inferior left second molar. Mesio-distal longitu- dinal section, showing root- canals. Fig. 548. — Inferior left second molar. Base of pulp-chamber, showing entrance to root- canals. Fig. 549.— Inferior left third molar. Mesio-distal longitu- dinal section, showing root- canals. Fig. 550. — Inferior left third molar. Base of pulp-cham- ber, showing entrance to root- canals. Fig. 551. — A, double-rooted superior lateral incisor; B. united superior central and lateral incisors; C, superior cuspid ; D, double-rooted superior bicuspid. 1 M ) ] Fig. 552. — A, D, superior cuspids ; B, C, double-rooted superior cuspids ; E. multiple-rooted superior bicuspid. Fig. 553. — Superior bicuspids. 1 i Fig. 554.— Superior bicuspid and molars. Fig. 555. — Inferior first bicuspids, Fig. 556. — Inferior molars and bicuspids. Fig. 557. — Inferior molars. PULPLESS TEETH AND FILLING PULP-CANALS. 435 Fig. 568. Fig. 559. Fig. 560. Gates-Glidden drills. The most satisfactory instrument for making these openings is the spear- pointed drill, care being taken not to drive the drill beyond the floor of the pulp-chamber in those teeth which have multiple roots, as by so doing it might penetrate the bifurcation. In the superior first bicuspids and the molars generally this opening needs to be considerably enlarged in order to enter their root-canals, as they usually form divergent angles to the floor of the pulp-chamber. This enlargement may be accomplished with cross- cut fissure burs or cone burs. Enlarging the Pulp-Canals.— The question of the propriety of me- chanically enlarging the pulp-canals is one upon which there is a consid- erable difference of opinion. Some operators claim that a perfect cleansing of the canals cannot be accomplished without it, nor the canals perfectly filled except by such preparation. Others maintain that any canal which will admit a Donaldson bristle (Fig. 558) can be per- fectly cleansed without enlarg- ing it, and those cases in which the canals are so small that they will not permit the bristle to enter need no cleansing orfilling. The writer prefers a middle ground be- tween these two extremes. There is always danger in extremes, both of theory and prac- tice ; it is, therefore, better to try to avoid the errors of over-enthusiasm, but keep so alert for the truth that it does not escape us. Nearly every pulp- canal that will permit the passage of a broach or a Donaldson bristle is placed in better condition for cleansing and filling by being opened and enlarged with a reamer or Gates-Glidden drill (Fig. 559) for at least a part of its extent ; but the dangers are so great, if the root is curved or very much flattened mesio-distally, of making an aperture through the side of the root, or near its apex, or of forcing septic material through the apical foramen, or breaking off the head of the drill and leaving it lodged in the canal, that these in- struments should be used with the greatest caution. Break- ing the drill while reaming the canal is much more liable to occur if the burring engine is used than when hand in- struments are employed. Swiss jewellers' broaches of spring temper are very valuable instruments for enlarging the pulp-canals and cleansing them of debris, and are much less liable to be broken and lodged in the canal than any other form of instrument. They cut much slower and do not clog so readily as the Gates-Glidden drill, and for these reasons, in small and Donaldson Bristles. Donaldson pulp- canal cleansers. 436 OPERATIVE DENTISTRY. constricted canals they are much the safest instruments to use. The break- ing of an instrument in a pulp-canal is an exceedingly vexatious accident, Fig. 561. : -Drawn temper. Fig. 562. Spring temper.- Nerve extractors. as its removal often entails no inconsiderable amount of labor and the consumption of much valuable time. After the orifice of the pulp-canal has been sufficiently en- larged to suit the purpose, it should be thoroughly cleansed of all debris by the aid of the Donaldson pulp-canal cleansers (Fig. 560) or the nerve extractors shown in Figs. 561 and 562. Hydrochloric and suli3huric acids are recommended by Calla- han and others for chemically enlarging the pulp-canals. These agents in twenty-five to fifty per cent, solutions are conveyed to the canals upon a platinum bristle or probe and carefully in- sinuated. The affinity of these acids for the lime-salts is such that the walls of the canals are rapidly softened and disinte- grated. The softened material is then readily removed with the Donaldson pulp-canal cleanser. The action of the acid may be limited by saturating the canals with a solution of sodium bicar- bonate. The third step in the operation is the local application of such therapeutic agents as possess germicidal, antiseptic, and disinfect- ant properties. These agents all have in common the property of destroying pathogenic and saprophytic micro-organisms, pre- venting the development of their spores, or of rendering inert or innocuous their waste products. They differ, however, very markedly in other respects ; for instance, some of them coagulate albumin, while others do not. The former are therefore classed as coagulants, the latter as non-coagulants. To the first class belong all of the salts of metals and the alcohols, to the second very many of the essential oils. The non-coagulants possess, in a great degree, the power of diffusion, and maintain their antiseptic properties for a longer period than the coagulants ; hence in the treatment of pulpless teeth these agents are considered by many operators to be more valuable for this purpose than the coagulants. The metallic salts, which possess decided germicidal antiseptic and dis- Nerve extractor, with holder. PULPLESS TEETH AND FILLING PULP-CANALS. 437 infectant properties, are the zinc chloride (ZnCl.^), aluminum chloride (AljClg), mercuric chloride (HgCl2), auric chloride (AUCI3), sodium sul- phite (Na^SOg), cupric sulphate (CuSO^jSH^O), and the argentic nitrate (AgNOg) . These have all been tested as germicidal agents in the treatment of septic pulp-canals, but all except the zinc and aluminum chlorides and the sodium sulphite have been discarded on account of the discolorations which they produce. The alcohols which are commonly employed in the treatment of septic pulp-canals are the ethylic or commercial alcohol, phenylic alcohol, — viz., carbolic acid, — and creosote, with the coal-tar derivatives, the cresols. Formol is also a very valuable therapeutic agent for disinfecting septic pulp-canals. The forty per cent, solution is reduced to a solution of two to three per cent, for dental use. Stronger solutions are irritating and coagulating. The essential oils which are most in favor for the treatment of septic conditions of the pulp-canals are those of cloves, cinnamon, cassia, thyme, and eucalyptus. They are not, however, so powerful in their germicidal action as the coagulants. Certain mineral acids have also been recommended for this purpose, — viz., the hydrochloric and sulphuric acids. They destroy micro-organisms by their intense chemic action, while the alkalies which have been employed are a combination of potassium and sodium, — Schreier's alloy, known under the name of kalium-natrium, sodium carbonate (NajCOgjlOH^O), and sodium dioxide (Na^O.^). These agents act by saponifying the fatty matter formed by the decomposition of albuminous substances and dissolv- ing the albuminous substances contained in the pulp-canal. Oxygen and chlorine gases in the nascent state have also been employed for the purpose of rendering the pulp-canals and the dentin sterile. Oxy- gen is still extensively used. These agents are also employed for the pur- pose of bleaching discolored teeth, the process of sterilization, however, progressing with the penetration of their bleaching action. Oxygen gas is obtained by the introduction into the pulp-canals of aqueous and etherial solutions of hydrogen dioxide (HjOj) or solutions of sodium dioxide (I^ajOJ. These agents when placed in contact with de- composing albuminous substances give up one atom of their oxygen ; the liberated oxygen acting as an oxidizer. The former is decomjDOsed into water and nascent oxygen, the latter into sodium hydroxide and nascent oxygen. Chlorine is usually employed in the form of hypochlorites, usually in solutions made by the electrolytic action of powerful electric currents upon sea- water. These preparations have the name of electrozone and meditrina. Iodine and bromine and their preparations are also powerful sterilizing agents. Iodine is usually employed in the form of the tincture. lodol and iodoform are objectionable for use about the mouth on account of their disagreeable odor. Bromine is objectionable for the same reason, and also for its intense irritating effects. Aristol, which is a combination of thymol and iodine, — dithymol binio- 438 OPERATIVE DENTISTRY, dide, — is a fovorite remedy with many operators for sterilizing putrescent pulp-canals. Hydronaplithol and a number of similar agents have been recommended from time to time, and have been used with considerable success. Authorities differ as to the diffusibility of the coagulants. Some have maintained, notably Harlan,* that zinc chloride and carbolic acid, by their coagulating effect upon albumin, did not become diffused through the dentin ; while, upon the other hand, such authorities as Truman, f Kirk, X and York § have maintained an opposite view. Formol coagulates albumin, mucin, and gelatin, the coagulum main- taining its form for an indefinite period, and appears to be rendered per- manently sterile so far as the action of the organisms of decomposition are concerned. MATERIALS EMPLOYED POR FILLING PULP-CANALS AND METHODS OF INTRODUCTION. The pulp-canals having been properly prepared and sterilized are now ready for the introduction of the material which is to occupy the space in the canals formerly held by the dental pulp. The main object sought in filling the pulp -canal is to hermetically close or seal the apical foramen, and thus to prevent the egress of septic material, mephitic gases, micro- organisms, or their waste products from the canal into the apical space, and also to preclude the possibility of the entrance by transudation of fluids from the apical tissues into the canal. These materials should be of such a character that they will remain unchanged by any influence which may be brought to bear upon them in such an environment. They must be unirri- tating to the soft tissues, impervious to moisture, susceptible of such ready adaptability to the walls of the canal as to insure a moisture-tight filling, and should possess antiseptic properties, or at least be capable of being rendered absolutely sterile when introduced. The materials which are used for this purpose may be divided into three classes, — viz., solids, plastics, 'dnd fluids. These materials are, however, often combined, the solids being used as the medium whereby the x)lastic and fl.uid substances are introduced into the canal. The solid materials comprise gold-foil in various forms, tin-foil in shreds or pellets, gold and copper wire, lead and wood points, the latter made of hickory or orange- wood and saturated with creosote. The base metals, which are readily oxidized, have never been extensively employed on account of their liability to cause discoloration of the dentin, though from the therapeutic stand-point this quality sometimes renders them very valuable. The plastic materials which are most commonly em- ployed are zinc oxychloride and softened gutta-percha points. Cotton, silk, and asbestos fibre are sometimes used as the vehicle for introducing zinc oxychloride and other plastic materials into the pulp-canal. The * Dental Eeview, vol. x. p. 44. t Proceedings Academy of Stomatology, Philadelphia, 1894. X Dental Cosmos, vol. xxxvi. p. 181. § Transactions Illinois State Dental Society, 1897. PULPLESS TEETH AND FILLINa PULP-CANALS. 439 objection to the use of a vegetable fibre like cotton as a filling for pulp- canals is overcome when it is emi)loyed in conjunction with the zinc chloride, "as it converts the cellulose of the cotton fibre into a pectous substance called amyloid, which is colorless and unchangeable in the conditions existing at the apex of a pulp-canal." * The fluid substances used for this purpose are gutta-percha — either the red base-]3late or the white stopping — dissolved in chloroform, the familiar chlora-percha, and salol, and paraffin. The two latter substances are rendered fluid by heat before being introduced. On cooling they become hard. FiCx. 563. Fig. 564. Pulp-canal pluggers. Gold-foil was the first material used for the i^urpose of filling root- canals, and was introduced by the late Dr. Maynard, of Washington, D. C, about the year 1838. His raethod was to use narrow strips of heavy non- cohesive foil, and to pack this into the canal with delicate pluggers (Fig. 563) made for the purpose. When skilfully done it could be made to hermetically seal the apical foramen, but its removal, if circumstances required, was well-nigh impos- sible. For many years the older operators relied entirely upon this method of filling the pulp-canal. Tin is thought by some authorities to be sux3erior to gold, for the reasons that it is more easily introduced and when oxidized pos- sesses antiseptic properties. Dr. W. S. How recommended the use of shredded tin for sealing the apical foramen. To avoid the danger of forcing the tin beyond the apical foramen a series of fine probes are used to measure the depth of the canal, as shown in Fig. 564, the clutch making it possible to meas- ure it exactly. With these probes the particles of shredded tin-foil are carried to the apex and impacted into position. Canal probe gauge. This method is open to the same objection as gold, in that it cannot be removed from the pulp-cavity. The advocates of this method of filling pulp-canals assert that this objection is not a valid one, Kirk, American Text-Book of Operative Dentistry, p. 325. 440 OPERATIVE DENTISTRY. for if the canal lias been properly prei)ared and sterilized and tlie material skilfnlly introdnced snch a necessitj'^ never arises. Gold, copper, and lead points are made by shaping sections of these metals to fit the caliber of the canal, the right length being ascertained by measuring the depth of the canal with a suitable probe or pulp- canal bristle. The late Dr. W. H. Morrison, of St. Louis, was the first to sug- gest the use of gold points for filling pulp-canals, which he recommended should be made from very soft pure gold wire shaped to fit the canal and of such length as not to pass the apical foramen when driven home. When introduced in conjunction with the plastic or fluid materials used for this purpose they can be made to perfectly seal the apical foramen as well as the entire length of the canal. Wood x)oints are but little used at the present day, although thirty to thirty-five years ago they were for a time quite extensively emi^loyed. They had the advantage, when saturated with creosote, of remaining per- manently antiseptic, but there was no assurance that the apical foramen was hermetically sealed unless used in conjunction with the plastic mate- rials, or that when the point was driven into the canal it did not project beyond the apical foramen. Cotton saturated with creosote or carbolic acid was recommended many years ago as a permanent filling for pulp-canals by Dr. J. Foster Flagg, and for a long time it was extensively emiDloyed. It, however, did not fulfil the expectations of some of its most ardent advocates, especially when carbolic acid was used as the antiseptic, for pericementitis and alveolar abscess was not an infrequent sequel after a few months or years. When creosote was used the results were much better, as the antiseptic properties of this agent are more permanent. But neither carbolic acid nor creosote retain their antiseptic properties very long in such an environ- ment. At the present time this material is rarely used as a permanent pulp-canal filling unless combined with zinc oxychloride. Since the dentist is now suj)plied with materials which are so much more reliable for this purpose, there seems to be no excuse for using a material whose only qualification is that it can be easily introduced. The writer has removed many of the cotton fillings, and with few ex- ceptions — and these had been saturated with creosote — they were vile- smelling and disgusting, while some of them were saturated with septic matter, discolored, and positively rotten. Zinc oxychloride has been demonstrated by abundant clinical experience to be one of the most valuable of the materials employed for filling pulp- canals. When mixed to the consistency of a creamy paste it can be readily introduced into any accessible canal by the aid of a fine pulp-canal bristle and using a gentle pumping motion. Or it may be introduced upon fibres of cotton or silk. After it has set it is very hard, and has the advantage of remaining antiseptic for a considerable period thereafter, on account of the excess of the zinc chloride which is usually present in this cement. Care must be exercised not to allow the cement to pass the apical foramen, as it is very irritating to the soft tissues. Its peculiar coagulating and mummifying effect upon any remnants of tlie pulp and the contents of PULPLESS TEETH AND FILLING PULP-CANALS. 441 the tnbuli prevents decomposition of these tissues and preserves the normal color of the dentin. If the removal of the cement become necessary, it may be accom- plished with Callahan's method of enlarging pulp-canals with sulphuric acid. Gutta-percha is also one of the most valuable materials for filling pulp- canals, many operators preferring it to the zinc oxychloride. Gutta-percha cones of proper shape and length, made from either the base-plate or the white stopping, when rendered plastic by heat or the action of chloroform, the volatile extract of eucalyptus, or the oil of cajuput, are most easily and successfully introduced even into tortuous and very fine canals. If the x^ulp- canals are first filled with a thin solution of chlora-percha and the material worked as far towards the apex as possible with a fine Donaldson bristle, or if moistened with the volatile extract of eucalyptus, or the oil of cajuput, the surface of the gutta-percha point will be rendered plastic and antiseptic. After being carefully placed in j^osi- tion and warmed by a blast of heated air directed upon it from a hot-air syringe, it will, under a little pressure from the pulp-canal plugger, readily slip into place, sealing the apical foramen, and by adding other cones the entire caliber of the canal may be filled to the orifice. In tortuous canals, by a little extra pressure the fluid gutta-percha can be made to penetrate to the very apex. If the canal has been thoroughly dried before the intro- duction of the filling, the gutta-percha will adhere very closely to the walls of the canal. This material is unchangeable in such an environment, and is the most bland and non- irritating to the soft tissues of any of the ma- terials which are used for this purpose. It may be removed by first soften- ing it with chloroform, and then thrusting a barbed broach into it and twisting the broach as is done in extirpating a devitalized pulp. In the introduction of gutta-percha points care should be taken not to use so much force in packing them into place as to cause any portion to escape into the apical space. To prevent air being forced into the space by the introduction of the cone, the canal should be first filled with fluid chlora-percha and carefully worked to the apex with a fine probe. If the pressure is made gently and the patient warned to give notice as soon as the least sensitiveness is felt at the apex of the root, this accident may be avoided. This suggestion is applicable to the introduction of all forms of pulp-canal fillings. Pressure of the filling upon the tissues of the apical space, or the presence of air or septic debris forced through the foramen in front of the filling, always induces more or less pericemental irritation, and not infrequently results in alveolar abscess. Ottolengui suggests the preparation of gutta-percha points or cones with a strand of silk in the centre, so that if it become necessary to remove the filling it can be more readily done if the cones have been prepared in this manner. His method of preparing the cones is as follows : ' ^ Take floss- silk and wax it thoroughly, after which dip it into chlora-percha and cut it into pieces about an inch long. These when dry give gutta-percha cones which have a strand of silk through them. They are readily packed into the canal, and the end, being allowed to extend beyond the orifice of 442 OPERATIVE DENTISTRY. the canal, is readily grasped, in case of need, with a pair of tweezers, whereupon the whole root-filling is easily withdrawn." Theo. von Beust,* of Dresden, Germany, suggests the following method of preparing cones for root-fillings : ''Take fine silver wire of from 0.02 to 0.05 millimetre in diameter, and cut from the different thicknesses of wire lengths to correspond to the different sizes of root- canals. These are tapered and roughened and surrounded with a film of gutta-percha, making the point cylindrical or cone-shaped, very like the root-canal points bought at the dejjots. A hook is then turned at the end of the point which is to occupy the coronal portion of the pulp-cavity. This makes an ordinary root-canal point of gutta-percha with a core of wire in the centre and a hook at the large end." By this method it is i^ossible to remove the root- filling entire, should occasion require, by simply grasping the hook with a pair of dressing forceps. The point is inserted in the canal after the manner already described for other gutta-percha points. Chlora-percha has its chief value in that it is capable, while in the fluid state, of being introduced into portions of certain canals in which solid materials could not be made to enter on account of their extreme smallness or their tortuous course. It is valuable, also, as a lubricant for the gutta- percha and metal points, and for closing the interstices between these materials and the walls of the canal. In introducing chlora-percha into tortuous and very small canals, it should be made quite thin and worked towards the apex as far as possible with fine Donaldson bristles ; then, by the aid of the How probes or other suitable instruments, fine threads of base-plate gutta-percha may be warmed and packed into the canals until they are full, when, if the patient has given no response to the forcing of the gutta-percha into the canals, a large piece of gutta-percha base-i^late may be warmed and packed into the bot- tom of the cavity, and this covered with a pledget of cotton large enough to fill the cavity ; then, with as large a plugger as will enter the cavity, pack the cotton, gently at first, and gradually increasing the force until the patient feels a slight pressure at the apex, when all further forcing of the material should cease, as this indicates that the chlora-percha has reached the apex of the canal. Dr. W. C. Barrett, t of Buffalo, some years ago most convincingly demonstrated that not only would the chlora-percha travel by this method to the very aiDex of the canal, but that it might also follow certain minute canals which sometimes connect the pulp with the pericementum at some distance from the apex of the root. Salol and paraffin have been so recently recommended as materials for filling pulp-canals that it is too early to pass judgment ui^on their utility or permanent value. They are both introduced in the same manner. A fine probe is first passed into the canal to the apex ; a portion of the agent to be used is then taken up between the points of a pair of dressing pliers and heated over an alcohol flame until it is melted. While still hot the pliers are inserted into the cavity of the tooth, beside the probe, and then * Items of Interest, October, 1900, p. 713. t Independent Practitioner. PULPLESS TEETH AND TILLING PULP-CANALS. 443 opened. The fluid material immediately follows the probe to the apex of the canal, and on slowly withdrawing the jjrobe while the material is still fluid it occupies the space of the probe and completely fills the canal. Some operators are in the habit of inserting a gutta-percha or a metal cone into the canal while the material is still fluid, thus insuring the material reaching the apex and perfectly filling the whole canal. This method has another advantage which gives it imi)ortance, — viz., if it become necessary to remove the filling, a blast of hot air from a chip-blower, or the contact of a hot instrument with the filling, will melt the material and permit the cone of gutta-percha or metal to be easily withdrawn. Parafiin does not change its conditions in such an environment ; but this does not seem to be the case with salol, as several reliable observers have claimed that it has disappeared from the canals in which it had been placed, probably by volatilization and diffusion through the dentin. If pericemental soreness should follow the permanent filling of the pulp- canal, and this not infrequently happens, it may be relieved by painting the gum over the affected tooth with a counterirritant like tincture of aco- nite and tincture of iodine, equal parts of each ; or chloroform may be added in the same proportions. Mummification of the Pulp. — It has been frequently noticed, as far back as the days when arsenous acid was employed to relieve hyper- sensitiveness of the dentin, that after a time the tooth became slightly discolored and all sensitiveness disappeared ; later, when occasion of- fered to open the pulp-chamber, the pulp was found not only dead, but completely desiccated or mummified, although in many of these cases no pericementitis was ever manifest. It has also been noticed, when por- tions of a pulp, devitalized by arsenous acid, had been left in the apex of the root, that very often such remnants, after having been treated with creosote or zinc chloride solutions, gave no further trouble whatever. The same conditions often occurred under fillings and cappings made of zinc oxy chloride, and when the pulp- canals were opened, perhaps years after- wards, the pulps were found in a complete state of mummification. This was noticed also under amalgam fillings made of cadmium or con- taining large quantities of this metal. These facts have led many operators to experiment with various antisex^tic agents in the hope of discovering some method whereby it would be possible to render such remnants of pulp-tissue, as must often be left in tortuous and crooked pulp-canals, per- manently aseptic, and thereby insure the possibility of its never causing pericementitis or alveolar abscess. Witzel (1874), according to Miller,* was the first experimenter to insti- tute systematic observations upon the subject. Witzel' s method was to devitalize the bulbous portion of the pulp by means of arsenous acid, ex- tirj)ate that part, and leave the portions in the canals undisturbed, treating these portions as freshly exposed pulps. This is the method followed later by Herbst, the only difference being that Herbst used native arsenic — cobalt — instead of the regular arsenous acid. * Proceedings Columbian Dental Congress, 1893. 444 OPERATIVE DENTISTRY. A few cases treated after this manner do well, but the great majority of them sooner or later develop pericementitis and alveolar abscess. Miller found that only a very small number of the antiseptic agents have any permanent sterilizing action upon the pulp. These are the cyanide, bichloride, and salicylate of mercury, sulphate of copper, and the oil of cinnamon. The preparation which gave the best results was com- posed of mercuric chloride, 0.0075 gramme, and thymol, 0.0075 gramme, made into tablets. The method of employing this preparation is to devitalize the pulp and remove all that is readily accessible, then place one of the tablets in the pulp-cavity, crush it with an amalgam plugger, working it down into the canals as far as possible, and cover it with gold-foil. The great objec- tion to this preparation is that the mercuric salt discolors the tooth. This same experimenter expresses great faith in the power of the oil of cinnamon to permanently sterilize any fragments of pulp -tissue that may from necessity be left in the pulp-canals. The only objection to the use of this agent, and also of oil of cassia, is their liability to produce a greenish discoloration of the tooth. Continuing the same line of experimentation, Soderberg has found the following formula to be very efficacious as a means for permanent pulp sterilization : B Alum exsic, Thymol, Glycerol, aa equal parts ; Zinc oxide, q. s. to make a stiff paste. Frith claims good results from the following formulae : B Tannic acid. Thymol, aa equal parts ; Glycerol, q. s. to make a stiff paste. B Mercuric chloride, Thymol, Acidi carbolici, aa 2 grammes ; Acidi tannici, Morph. mur., aa 1.5 grammes ; 01. menth., 01. cassige, aa q. s. to make a stiff paste. "With the latter ^ ' a tannate of mercury is formed ; it is insoluble, and but little pain is caused by its absorption." The method of applying these sterilizing agents is to remove all of the pulp-tissue that is possible, then to place a portion of the paste in the pulp-chamber and with a root-canal plugger carry it into the canals, and then add enough more to fill the pulp-chamber, cover it with zinc oxyphosphate, and fill with gold or amalgam as the conditions require. Sdderberg has more recently suggested that a small quantity of cocaine PULPLESS TEETH AND FILLING PULP- CANALS. 445 be added to the paste to prevent tlie pain incident to the action of the dried alum upon the pulp-tissue. Objections have been raised to the employment of such methods of treatment, for the reason that it was feared it would tend towards slovenly methods of operation, as it would be much easier to apply the paste than to carefully follow the pulp-canals until all remnants of pulp-tissue that skill and patience could reach were removed. The advantages of the method lie in the possibility of so sterilizing the remnants which cannot with the utmost skill be removed that there will be little or no probability of their ever causing future trouble. CHAPTEE XXYII. BLEACHING DISCOLORED TEETH. Discoloration of a tooth is tlie result of tlie deatli of its pulp, tlie dis- organization of tlie red blood- corpuscles, and tlie dissemination of the hsemogiobin through the dentinal tubuli. It should be understood, how- ever, that in this connection no reference is made to those metallic stains resulting from the oxidation of amalgam fillings containing large amounts of silver or cadmium, or from other conditions which may be operative in the mouth, like the chromogenic action of certain bacteria, tobacco, medicines containing iron, etc. Chemistry has not as yet discovered any reliable and effective method of removing the metallic stains caused by the oxidation of metal fillings, etc. The death of the pulp does not of necessity result in discoloration of the tooth, but loss of its translucency or vital appearance is always a re- sultant of pulp devitalization. This appearance once lost can never again be restored by any means known to chemistry or dental art. Discolora- tion may be removed and the tooth whitened, but a natural ajipearance in color or translucency can never be obtained. The removal of discolora- tion may be accomplished by two methods : first, by chemic agents, and secondly, by the color effect obtained by the introduction of a white filling- material into the enlarged cavity and pulp- canal. By such means it is possible to greatly improve the color, and this improvement is most marked in those teeth which are most discolored. The first noticeable change in the color of a tooth which has had its pulp devitalized by any of the various causes which may produce this condition is that of a pinkish tint. The discoloration in devitalized or pulpless teeth ranges from a pinkish tint to black. These gradations in color pass rapidly ''from the original pinkish hue, which becomes yellow ; this, growing darker, passes into brown, and after the lapse of considerable time the tooth may become a permanent slaty gray or black." (Kirk.) It is a notable fact, however, that the character of the agency which has caused the devitalization of the pulj) determines to a considerable de- gree the rapidity with which discoloration of the tooth ensues. Trauma- tisms which produce severe injury to the pulp, rupturing its blood-vessels and causing extravasation of blood into its tissues, result in almost imme- diate discoloration of the tooth. Intense irritation, such as is produced by the application of arsenic trioxide, zinc chloride, or other violent irritants which cause infarction, embolism, or thrombosis, sometimes result in dis- coloration in less than twenty-four hours after their application. A severe pulpitis, lasting for t\t'0 or three days before the vitality of the pulp is destroyed, does not cause discoloration nearly so readily ; while if the in- flammation has been of a mild type and the devitalization of the pulp has 446 BLEACHING DISCOLOEED TEETH. 447 progressed slowly, the initial discoloration may be so slight as to escape notice except by reflected light. If, however, the devitalized pulp is permitted to remain in the tooth for any length of time the color gradually grows darker, and although it may never become so unsightly as those which have been devitalized by mgre violent irritants, they will in time assume a color which will call for treatment to render them less conspicuous. Teeth, however, in which the pulp has been removed immediately after devitalization, or while it is in a state of irritability, but before stasis, embolism, or thrombosis has occurred, do not, as a rule, become discolored. The only change noticed in them is the loss of translucency. Pathology. — Black has found the coloring matter of the red blood- corpuscles in a crystalline form in the blood- clots found in devitalized pulps, and that while the clots are in a state of solution from disintegra- tion the coloring matter may enter the tubules in large amount and cause the discoloration of the entire dentin, giving it a red color. The decomposition of the proteid elements of the pulp exerts a pro- found modifying influence* upon the extent and the intensity of the dis- coloration by the formation of hydrogen sulphide and its action upon the hsemogiobin. Healthy blood contains on an average twelve per cent, of hsemoglobin. (Vaughn.)* The crj^stals of hiemoglobiu have the bright red color of arte- rial blood ; this explains the initial pinkish hue or the red color which obtains in certain teeth immediately after devitalization of the pulp. Hsemoglobin has the power of forming rapid association and dissociation with oxygen without affecting the molecular arrangement of the hsemo- globin itself. In fact, it is the oxygen carrier of the red blood-corpuscle. Haemoglobin is a proteid body combined with hsematin, a body of known composition containing iron (Cj^HgjjST^FeOs). The term oxyhwmoglobin is used to designate the hsemoglobin while it carries the oxygen, and in contradistinction to the hsemoglobin from which the oxygen has been removed. Arterial blood contains a considerable quantity of oxyhsemoglobin, but very little reduced hsemoglobin ; while venous blood is x)Oor in the former and rich in the latter. (Vaughn. )f The association of oxygen with hsemoglobin, although a chemic com- bination, is of such a nature that the oxygen is readily given up and replaced without detriment to the hsemoglobin molecule. The red blood- corpuscle is therefore able to receive its oxygen as it passes through the pulmonarj^ circulation, and give it up again in its passage through the capillary system, without material change in the corpuscle itself. 'So accurate formulse have been found for the proteids. Bunge gives the following analysis as the range of variation in their composition : Carbon 50.0 to 55.0 per cent. Hydrogen 6.6 to 7.3 per cent. Nitrogen 15.0 to 19.0 per cent. Sulphur 0.3 to 2.4 per cent. Oxygen 19.0 to 24.0 per cent. * Chemical Physiology and Pathology. t Ibid. 448 OPEEATIVE DEJSTISTRY. According to Wurtz their composition is as follows : Carbon 52.7 to 54.5 per cent. Hydrogen 6.9 to 7.3 per cent. Nitrogen 15.4 to 17.0 per cent. Oxygen 20.9 to 23.5 per cent. Sulphur 0.8 to 2.2 per cent. It will be seen, therefore, that according to the analysis of Biinge the albumins contain approximately from 6.6 to 7.3 per cent, of hydrogen and from 0.3 to 2.4 per cent, of sulphur, while those of Wurtz place the per- centage of hydrogen at 6.9 to 7.3 and sulphur at 0.8 to 2.2 per cent. In the putrefaction of the animal albumins these substances are decom- posed into fat, tyrosin, leucin, ammonia, hydrogen sulphide, carbon dioxide, hydrogen, and nitrogen. The hydrogen sulphide is formed by the union of two atoms of hydrogen with one of sulphur. This gas acting upon the haemoglobin and certain of its compounds, formed by decomposition, — viz., methsemoglobin, hsemin, haematin, and hsematoidin, — present various chro- mogenic features which explain the color changes that take place in the tooth during the decomposition of the albuminoid substances of the pulp, the organic material of the dentin, and the haemoglobin of the blood con- tained in this organ at the time of its devitalization. These compounds form various colors. The crystals of hcemogloUn are bright red ; those of methcemogloMn are reddish brown ; those of hcemin are dark brown or black ; those of hcematin are bluish black ; and those of hcematoidin are reddish or orange- colored. '•Extravasations of blood quickly undergo changes which are visible even to the naked eye. In the skin they are at first brownish, then blue- green and yellow. When small hemorrhages have occurred in the sub- stance of a tissue, as the periosteum, pleura, or lung, reddish-brown or blackish spots will be visible long afterwards. In bodies which are rapidly putrefying these areas may be slate- colored. ' ' Larger hemorrhages into the tissues — for example, in the brain or the lung — come to have a rusty color after a time, and still later the affected spots show ochre-yellow, yellowish-brown, or brown pigmentation. Corre- sponding with all these changes in color are physical and chemical changes in the haemoglobin and in the iron contained in it." * During the process of disintegration of the red corpuscles of the blood the haemoglobin breaks up into ''two groups of substances, one containing iron and the other not ; the former is called hcemosiderin, the latter hw7na- toidin.'' t Hcematoidin is chemically identical with MliruMn, the chief coloring matter of the bile ; and, as already noticed, it is reddish or orange- colored in its crystalline form. " It appears to be more abundant when the blood- pigment is not much exposed to the action of living cells, as in the centre of large extravasations, and in hemorrhages into preformed cavities of the body, as, for example, into the pelvis of the kidney or into the subdural space." X For this reason it would seem that the same conditions would * Ziegler, General Pathology, 1899. t Ibid. J Ibid. BLEACHING DISCOLORED TEETH. 449 obtain in a closed cavity like the pulp-chamber, which had not been pene- trated by caries or traumatism, and which would, upon the devitalization of the pulp, be devoid of living cells in contact with it, and would thus explain the reddish or reddish-yellow discoloration of the teeth. '^ Swmosiderin, the derivative of haemoglobin containing iron, is met with in the tissues for the most part in the form of yellow, orange, or brown masses and granules, which deepen in color with time. ... If hsemosiderin comes in contact with ammonium sulphide (or hydrogen sul- phide, both of which are derivatives of the putrefactive decomposition of the animal albumins), it becomes black by the formation of iron sul- phide." * The conditions for the formation of iron sulphide are present in a tooth containing a dead and putrefying pulp, and it may be safely inferred that this process takes place within the tooth as the result of the chemic changes which are brought about through the agency of the saprophytic micro-organisms acting upon the proteid elements of the pulp-tissue, the blood, the contents of the tubuli, and the hsematin contained in the red corpuscles, the sulphur combining with the iron in the hsematin to form iron sulphide. Kirk f is of the opinion that ^' while iron sulphide as such cannot be held wholly accountable for the final bluish-black color of a tooth which has reached the stage of permanent discoloration, the pig- mentation is almost certainly due either to it or to some allied compound in which iron and sulphur, with some organic constituents, largely enter, and which by a further slight decomposition would yield true iron sul- phide." PREPARATION OF THE TOOTH FOR BLEACHING. Various chemic agents have been suggested for the purpose of bleach- ing discolored teeth and restoring them to their normal color. The majority of these agents are more or less irritating and escharotic, and more or less injurious to the surrounding soft tissues ; it is therefore important that the tissues of the apical space should be protected by the introduction of a filling that will hermetically seal the apical foramen, and at the same time of such material that it will not be acted upon by the chemic agent em- ployed. The only material used for filling teeth that possesses these quali- ties is gutta-percha. To protect the gums, lips, and other soft tissues of the mouth, and the adjoining teeth, from the destructive action of these chemic agents the rubber-dam is of the greatest value ; in fact, it is indis- pensable. The first step in the preparation of a tooth for the bleaching process — a superior central incisor, for instance — is to freely open the pulp-canal and remove any remaining portions of the pulp and other debris by means of a Donaldson pulp-canal cleanser. This is to be followed with repeated irri- gations with sterilized water rendered alkaline by the addition of a small quantity of sodium bicarbonate. The cavity of decay, if one exists, should now be cleaned of all deeply stained softened dentin, and thepulp- * Ziegler, General Pathology, 1899. t American Text-Book of Operative Dentistry. 29 450 OPERATIVE DENTISTRY. chamber and canal enlarged with suitable burs and reamers. If perice- mental irritation exists, this condition must first be abated. The rubber dam should now be adjusted, but to the tooth only that is to be operated upon, as by this means there is less danger from leakage than when two or more adjoining teeth are included in the dam, while the adjoining teeth are protected against injury from any disintegrating or solvent action upon the enamel which might be possessed by the chemic agents used for the purpose of bleaching. To secure the dam from slip- ]Ding off the tooth, and to guard against every possibility of leakage, a waxed ligature should be wrapped three or four times about the tooth at the cervix and tied with the surgeon's knot. Added security may be ob- tained by coating the ligature, — after it is in place, — the cervix of the tooth, and the rubber dam at this point with liquid chlora-percha. The cavity and the pulp-canal should now be dried with bibulous paper and amadou as thoroughly as may be with these absorbent agents, and further dehydrated by means of a Wooley or an Evans root- dryer or the hot-air sj^ringe. The root-canal should now be filled with gutta-percha, which should not include more than the apical third or half of the canal, for the reason that the discoloration of the tooth is most intense at the cer- vix and immediately beyond towards the apex, and if, as frequently hap- pens, there is recession of the gum, it is important that the bleaching process be carried beyond this point. All fillings of every kind which may be present in the tooth- crown should be removed before the bleaching process is commenced. This is especially necessary if the bleaching agent to be employed is one that con- tains chlorine, as this element readily combines with iron, gold, platinum, and other metals, forming soluble chlorides which, if i)ermitted to penetrate the tubular structure of the dentin, will cause iDcrmanent discolorations that are well-nigh impossible to remove. For this reason, also, the instru- ments which are used for mixing and introducing bleaching agents of this character should be made of wood or ivory. Another advantage in re- moving the fillings from such a tooth is the increased surface which is thus exposed to the action of the bleaching agent. The cavity should next be thoroughly prei^ared by removing all remains of softened dentin, thin walls of enamel, and any septic or other foreign substance. Kirk recommends washing the cavity after it is prepared with dilute ammonia water, or a hot solution of borax in distilled water in the proportion of one drachm to one ounce, to saponify and remove by solution all fatty matters which might otherwise obstruct the entrance of the bleaching agent to the tubular structures of the dentin. The surplus moisture should next be removed, and the tooth is then in condition for the bleaching process. Method of bleaching Teeth. — The chemic agents which have been most successfully used for the jDurpose of bleaching discoloi-ed teeth are of two classes, — oxidizing agents and reducing agents. The former destroy the color molecule by virtue of their power to evolve oxygen in a nascent state. The latter act in an opposite manner by virtue of their great affinity for oxygen, seizing upon the oxygen element of the color molecule to form by- BLEACHING DISCOLORED TEETH. 451 products, the character of which depends upon the chemic composition of the reducing agent employed. The oxidizing agents are divided into two forms, — viz., indirect oxidizers and direct oxidizers. The indirect oxidizing agents which are employed for bleaching teeth are chlorine in the form of chlorinated lime, chlorinated soda (Labarraque's solution), aluminum chloride, free chlorine gas, and iodine and bromine; the latter being used to remove various special metallic stains. The direct oxidizing agents are hydrogen dioxide, sodium dioxide, and potassium permanganate. The reducing type of bleaching agents is represented by sidphurous acid. Chlorine Methods.— Chlorine (CI) has a strong affinity for all metallic substances, and under favorable circumstances enters with great energy into direct combination with them, forming compounds which are generally soluble in water. One of the chief characteristics of chlorine is its strong affinity for hydrogen (H) wherever found. This peculiarity is utilized in the opera- tion of bleaching teeth by liberating the chlorine which is held in combina- tion with the calcium, sodium, and aluminum of the above-mentioned compounds. The bleaching power of the chlorine is exerted upon the color molecule by seizing upon its hydrogen element and liberating the oxygen (O) contained in it. The oxygen thus liberated is in the nascent state, and in this form it acts most powerfully as an oxidizing agent. By the union of the chlorine with the hydrogen element of the color molecule, or other molecules containing hydrogen, chlorhydric acid (HCl) is formed, and the identity of the substance acted upon is destroyed. The Truman Method. — Dr. James Truman (1864) introduced the first successful method of bleaching discolored teeth. His method consists substantially of liberating chlorine from chlorinated lime by the addition of a weak solution of acetic, tartaric, or oxalic acid. Dr. Truman has sug- gested several ways by which the chlorinated lime and the acid may be brought together. "One process is to saturate the entire canal and the pulp-chamber with the acid before inserting the chlorinated lime 5 another is to dip the instrument in the weak solution of acid, and then in the lime, and pack it rajDidly into the cavity ; and still another is to make a paste ^by the use of distilled water, and pack this into the tooth, and then apply a stronger acid solution by means of cotton wrapped around the point used." * The cavity is then quickly sealed with gutta-percha, zinc oxychloride, or zinc oxyphosphate. This method to be repeated every two or three days until the required shade is obtained. The failures which occur by the use of this method are due, in the opinion of Dr. Truman, to defective manipulation, princij)ally in the em- ployment of steel or any metal instruments, — as by their use metallic com- pounds are formed with the chlorine and permanent discolorations result, — * American System of Dentistry. 452 OPERATIVE DENTISTRY. and in the non-employment of distilled water in the various manipulations, for reasons that are manifest. After the desired color is obtained, the tooth must be filled with some material which will by its antiseptic and coagulating qualities prevent the future decomposition of the contents of the dentinal tubuli. Dr. Truman thinks zinc oxychloride possesses these qualities in a remarkable degree, and experience proves it to be a most satisfactory substance for this purpose. After the cement has set it should be protected with a gold filling. In the employment of chlorinated soda for the purpose of bleaching a tooth, the dentin is dehydrated as thoroughly as possible by the usual means, and afterwards saturated with the solution. A j)iece of absorbent cotton may then be saturated with a weak acid solution, placed in the cavity, and sealed in. The chemical action is substantially the same as when chlorinated lime is employed, — viz., the liberation of chlorine which combines with the hydrogen element of the color molecule, and sets free the oxygen element in a nascent state. • Another method of bleaching teeth with chlorine is that invented by Dr. Wright, of Richmond, Virginia. This method consisted of forcing a continuous stream of chlorine gas — previously prepared in the laboratory — into the pulp-canal and cavity of the tooth by an elaborate apparatus made especially for the purpose. The method was very efficient and rapid in its action, but the complications of the apparatus and the trouble of preparing the gas were obstacles which prevented its general adoption, and it was therefore abandoned. Dioxide Methodst — Hydrogen dioxide (HjOj) is one of the class of direct oxidizing agents. Its value as a bleaching agent lies in the fact that one of its atoms of oxygen is bound to the water molecule by such a weak chemic combination that it is readily disrupted, and one of its atoms of oxygen liberated, as nascent oxygen. Many substances are capable of disrupting this compound and converting it into water (H.^O) and free oxygen (O). Contact with fresh blood, pus, salivary secretions, inspis- sated mucus, albumin, and nearly every form of dead organic matter, causes disruption of the compound, the evolution of oxygen, and the decomposition, wholly or in part, of the organic matter with which it comes in contact. These characteristics make it not only a very valuable means for bleaching discolored teeth, but also as a cleansing agent and germicide in all operations upon the teeth and in diseased conditions of the mouth. The ordinary three or four per cent, aqueous solutions of hydrogen dioxide are of little value for the purpose of bleaching the teeth, as they are very unstable if kept for any length of time. Since the introduction of the ethereal solution prepared by McKesson and Eobbins, of N'ew York, known as '^caustic pyrozone," which contains twenty-five per cent, of hydrogen dioxide, the question of bleaching by the direct method has been solved, and this preparation is now largely used when this method is employed. The process of bleaching by this method is to apply the twenty- five per cent, ethereal solution to the pulp -canal and the cavity by means of BLEACHING DISCOLORED TEETH. 453 loosely twisted wisps of cotton, and following each application with blasts of heated air from the hot-air syringe until complete evaporation of the menstruum is obtained. This process is repeated two or three times at the same sitting, or until the desired restoration of color is secured. Failing in this, an application of pyrozone may be sealed in the cavity and per- mitted to remain for one or two days, when upon removing it and making another application and evaporating it to dryness the color will usually be restored. The pyrozone seems, from experience, to act more rapidly and its re- sults to be more permanent if it has been rendered alkaline before apply- ing it '^by the addition of a few drops of ammonice fortior, or by the solu- tion of one of the caustic alkalies, — e.g., sodium or potassium hydroxide or sodium dioxide." * Dr. D. I^. McQuillen, of Philadelphia, has suggested the treatment of the pulp-canal and cavity with Schreier's kalium-natrium preparation to secure the alkaline effect in the process. The debris caused by the action of the kalium-natrium is then carefully removed with instruments and pellets of cotton, the usual washing omitted, and the pyrozone applied as above. This method gives most excellent results, both in the greater rapidity with which the bleaching process takes place and in the permanency of the results. As soon as the desired restoration of color is obtained the tooth should be filled temporarily with some material which can be easily removed, so that if discoloration returns the bleaching process may be again applied with little loss of time, l^o tooth which has been bleached should be permanently filled for at least two or three months, or even longer, that the permanency of the restored color may be assured before this operation is undertaken. Dr. A. W. Harlan, of Chicago, introduced the use of aluminum chloride in connection with hydrogen dioxide. His method is to pack the aluminum salt into the cavity and then to moisten it with hydrogen dioxide. This was originally thought to be a chlorine process, whereby the chlorine in the aluminum salt was liberated by the action of the hydrogen dioxide ; but later experimentation has shown that the reaction is due to the cata- lytic action of the aluminum salt, and that the hydrogen dioxide compound is disrupted by contact with the former and nascent oxygen is set free. Kirk suggests that inasmuch as aluminum chloride is an active coagu- lant, it is contraindicated in the bleaching of teeth until the process has reached the stage where a fixative is needed to j)revent further decomposi- tion in the tubular structure of the dentin. Sodium dioxide (Na^O.^) is another of the class known as direct oxidizing agents. It is similar to hydrogen dioxide in that its combination with one of its atoms of oxygen is so weak that it readily gives it up when subjected to the same conditions that cause hydrogen dioxide to part with one of its atoms of oxygen. The essential difference, however, lies in the character of the by-products which are formed after its decomposition. * Kirk, American Text- Book of Operative Dentistry. 454 OPERATIVE DENTISTRY. Sodium dioxide is a strong caustic alkali, and after the loss of one of its atoms of oxygen it becomes N'a.O, still retaining its caustic and alkaline properties. When combined with water it is the ordinary caustic soda. The value which is possessed by sodium dioxide as an oxidizing or bleach- ing agent lies not only in the fact that its liberated atom of oxygen attacks the color molecule, but that it possesses great saponifying powers, which reach the oils and fats contained in the structures of the tooth and dissolve any organic matter still remaining. " For use as a bleaching agent it is applied to the dentin in a saturated solution. In making the solution especial care is necessary in order to avoid elevation of temi^erature, by reason of the energy with which it enters into combination with the water. If the solution is allowed to become heated in the making, decomposition of the compound with loss of oxygen occurs and its bleaching power is destroyed. The solution is best made by pouring into a small beaker, of about one ounce capacity, two drachms of distilled water and immersing the beaker in a large vessel or dish containing ice-water or pounded ice. The can containing the dioxide powder should then have its lid perforated with a number of small holes similar to the lid of a pepper caster, and the powder be slowly dusted into the distilled water in the small beaker. The powder is added to the water until the solution assumes a semi-opaque appearance, indicating the point of saturation. On removing the beaker from the cooling mixture, the dioxide solution will in a few minutes assume a transparent straw- colored appearance and be ready for use. ' ' * The method of apx)lication is similar to that employed when hydrogen dioxide is used, with the exception that pieces of asbestos felt are used instead of cotton with which to make the application, as the cotton fibre is acted upon by the sodium dioxide and converted into an amyloid sub- stance which interferes with the bleaching process of the solution. After the dentin has been thoroughly saturated with this solution a ten per cent, solution of sulphuric acid is applied, which neutralizes the alka- line condition, causing effervescence and the formation of sodium sulphate and hydrogen dioxide. The particular value of this method lies in the fact that it not only destroys the integrity of the color molecule, but the caustic alkali exerts a solvent action upon the organic material remaining in the dentinal tubuli, while the reaction which causes effervescence in the tubuli com- pletely removes the debris by mechanically forcing it out of the tubuli. It may be necessary to reapply the sodium dioxide, as one application does not always restore the color. Before doing this, however, the tooth should be thoroughly washed with hot distilled water. In the second appli- cation the acid should be omitted. After the color is restored the tooth should be again thoroughly washed with hot water to remove all debris, and after thorough desiccation the tooth is ready for the filling. Kirk recommends varnishing the walls of the cavity before introducing the fill- ing. Zinc oxychloride and zinc oxyphosphate cements are the best for * Kirk, American Text-Book of Operative Dentistry, p. 437. BLEACHING DISCOLORED TEETH. 455 these fillings on account of their better color, while the zinc chloride by its coagulating effect will effectually prevent putrefactive changes taking place in any portions of organic matter which might remain in the tubuli. Kirk claims for this method that it not only restores the color of the tooth but normal translucency as well, and he thinks the opaque, white effect which results from other methods is due to the bleached organic debris remaining in the tubuli, while in the sodium dioxide method this is removed by the solvent action of the strong caustic alkali. Sulphurous Anhydride Method. — ASfitZpAwrows acM (sulphurous anhy- dride, SO,) is the only one of the class of reducing agents that is used in the operation of bleaching teeth. Its value as a bleaching agent resides in its strong af&nity for oxygen. When applied to a discolored tooth, it decomposes the color molecule and combines with its oxygen element, thus destroying the identity of the molecule and of the color. Various methods have been suggested for utilizing the bleaching property of sulphurous acid by the direct application of the gas to the root-canal of discolored teeth. One of these methods comprehended making a solution of the gas in water and applying the solution to the pulp-canal and the cavity. Another was to ignite, by means of the electric cautery, a small piece of sulphur which had been placed in the pulp-canal. Both of these methods are oj)en to serious objections from the disagreeable odor and from their limited efficiency. To be efficient the gas must be confined within the cavity for some time, and with neither of these methods is such confinement possible. Kirk * has devised a method whereby it is possible to generate the gas from compounds placed within the pulj)-cavity, and confine it there as in the chlorine process of Dr. Truman. The bleaching compound is made as follows : "One hundred grains of sodium sulphite and seventy grains of boric acid are separately desiccated and afterwards ground together in a warm, dry mortar. The powder is then to be transferred to a tightly stoppered bottle. For bleaching purposes the powder is packed into the root-canal and cavity of the t<)oth, and then moistened with a drop of water, and the cavity immediately closed as tightly as possible with a stopping of gutta-percha, previously prepared and warmed. A reaction ensues between the boric acid and the sodium sulphite whereby sulphurous acid is liberated. The i^rocess is effective in many cases where the chlorine methods have failed, but is slow in its action, and is largely superseded by the dioxide- of- hydrogen and dioxide-of-sodium methods." Cataphoric Method. — In the bleaching of the teeth by the cataphoric method the power of the continuous galvanic current to disseminate, dif- fuse, and carry remedies into and through animal tissues is taken advan- tage of to bring about a more complete and perfect dissemination of the certain bleaching fluids used to restore the color of devitalized teeth. The same electric apiDaratus and appliances emiDloyed in the treatment of hypersensitive dentin are used in this method of bleaching teeth. The principles involving the application of the current and its control are also the same (see Chapter XIIL), the only difference being that the resistance * American Text-Book of Operative Dentistry, p. 439. 456 OPERATIVE DENTISTRY. Fig. 565. offered by a devitalized tooth is mucli greater than that of a vital tooth, which necessitates a much higher voltage (pressure) to carry the bleaching agent into the dentin. "While a current pressure of ten volts is all that can be utilized in the treatment of hypersensitive dentin, twenty-five to thirty, and even sixty volts, are sometimes required to drive a current of one and one-half milliamperes through devitalized dentin. The bleaching fluid which is used in connection with the galvanic cur- rent is a twenty-five per cent, aqueous solution of hydrogen dioxide to which has been added a small quantity of sodium chloride, sufficient to give it the strength of the normal salt solution used in transfusion, — one drachm to a pint of warm sterilized water, — as the addition of this salt increases the conductivity of the fiuid. The ethereal solution of hydrogen dioxide is too resistant to the current to be utilized in this connection. To prepare a twenty-five per cent, aqueous solution of hydrogen diox- ide, place in a test-tube one volume of normal salt solution and two volumes of twenty-five per cent, ethereal solution of hydrogen dioxide, and mix by shaking the test-tube. To remove the ether, place the solution in a small porcelain evaporating dish and gently heat over a water-bath until the ether is all evaporated, care being used not to allow the flame of the lamp to ignite the ether vapor. The hydrogen dioxide is thus dissolved in the water and the ether dispelled. Dr. Hollingsworth recommends adding one per cent, of zinc sulphate to the solution, which diminishes the resistance and exerts a coagulating effect upon the organic matter of the dentin, which gives translucency to the dentin and enhances the permanency of the operation. The same care must be exercised in isolating the tooth by the rubber dam, and securing it against leakage of moisture or leakage of the electric current, that is exercised in the treatment of hypersensitive dentin as already described in detail in the chapter previously referred to. The tooth being ready for the bleaching process, the aqueous solution of hydrogen dioxide is applied to the tooth-cavity on a pledget of cotton, which must at all times be kept moist with it, and the platinum point of a suitable anodal electrode placed in contact with it. The cathodal electrode, covered with sponge and moist- ened with the sodium chloride solution, may be held in the hand or applied to the side of the face or neck, and the current turned on, the same precautions being taken as when treating hypersensitive dentin. Short circuiting of the current is liable to occur if great care is not taken to keep the external sur- faces of the tooth dry. Some operators apply the cathode to the external surface of the tooth, and claim that more rapid effects are obtained on account of the shorter distance which the current has to travel. There is, however, considerable Syringe electrode. BLEACHING DISCOLORED TEETH. 457 danger of short-circuiting the current if the external surface of the tooth should become moistened, or by a movement of the patient the electrodes should accidentally come in contact with each other. The Hollingsworth syringe electrode (Fig. 565) may be used to keep the cotton moist with the bleaching fluid. To successfully employ the aqueous solution of hydrogen dioxide with the electric current, it is necessary to use a device which will permit the whole crown of the tooth to be enveloped in the bleaching fluid. Such a device has been invented by Dr. Hollingsworth, and described by him as follows: ''The bleaching electrode consists of a curved glass tube, with a metal top at one end, connecting with a spiral platinum wire in the tube (Fig. 566) and a rubber nipple (a) at the other end to enclose the tooth to be bleached. A metal cap plug (&) prevents the bleaching fluid from escaping, and the tip is provided with a groove for the at- tachment of the connecting cord. The appliance is held in place by the hooks attached to the metal tip of the tube, which are caught over the top of the rubber dam. "The duplex syringe (Fig. 567) is for the purpose of filling the tube and nipple with the bleaching fluid. The nozzle connects only with the rear Fig. 566. Fig. 567. Bleaching electrode. Duplex syringe. bulb. When this is charged with the bleaching fluid the nozzle is inserted in the tube of the bleaching electrode, first compressing the forward bulb and allowing it to expand to exhaust the air in the tube and nipple, when pressure upon the rear bulb forces the bleaching fluid into the electrode. "The nipple- expander (Fig. 568) is for adjusting the rubber nij)ple to the tooth that is to be bleached. The closed end of the nipple is first perforated with the rubber- dam punch, and when placed upon the tooth and ligated forms a close-fitting and tight holder for the bleaching fluid." Before adjusting the bleaching electrode, the tooth should be prepared as for bleaching by any of the methods already described ; the pulp-canal and the tooth-cavity are then loosely packed with cotton previously satu- rated with the bleaching fluid. The object of this is to form a conductor 458 OPERATIVE DENTISTRY. that will carry the fluid to the remote recesses of the cavity and canal, and also to exclude air-bubbles which would act as insulators of the electric current. Fig. 568. Nipple-expander. The first step in the adjustment of the electrode is the placing of the rubber nipple in position by means of the nipple-expander (Fig. 568) and securing it firmly by a ligature passed around it at the cervix of the tooth, varnish or chlora-percha to be flowed over it as an added precaution against leakage. The free end of the nipple is now forced over the shouldered end of the glass tube and the hooks adjusted to hold the opposite end of the tube in position. The tube is now to be filled with the bleaching fluid by in- serting the nozzle of the duplex syringe — which has been previously charged — into the metal tip of the tube, compressing the forward bulb to exhaust the air. If air finds its way into the tube at the cervix of the tooth beneath the margins of the rubber nipple, varnish may be again ap- plied, and suction will draw it into and fill any little interstices which might give access to air. The rear bulb is comjDressed and the tube filled with the bleaching fluids, thus submerging and surrounding the crown of the tooth in the fluid. The ^^" ' ■ positive pole is now con- nected with the metal end of the tube and the negative pole with the hand electrode, and these with the source of the current. Fig. 569 shows the bleach- ing electrode in position and connected with the positive pole. The current should be turned on slowly and the milliampere- meter closely watched ; a leak in the current is indicated by the registration of a greater amperage than is usually employed in such operations, — viz., one-tenth to one-half a milliampere upon vital teeth, which is increased to one and sometimes one and one-half milliamperes in bleaching devitalized teeth. CHAPTEE XXVIII. DISEASES OF THE PERICEMENTUM. The pericementum or peridental membrane is often the seat of various diseased, conditions, both nutritive and functional. Among these are several distinct forms of inflammation, all arising from different causes, some local in origin, others constitutional, and each requiring, according to their origin, a different line of treatment for their cure. B5decker classifies the diseases of the pericementum under two heads, ' — viz., purulent and non-purulent. Burchard thinks this is misleading, as cases may be due to septic causes without pus-formation, while pus-forma- tion represents but one form of sepsis. Burchard * classifies them as septic and non-sejriic. Black t classifies the disorders of the pericementum under three heads : first, diseases which begin at the apex of the root ; second, those which begin at the border of the gingivae ; third, those beginning at some inter- mediate portion of the membrane. These are again divided into septic and non-septic, general and localized, acute and chronic. pericementitis. Definition. — Pericementitis (from the Greek T:£pt, around; Latin, ccementum. cement ; Greek, cr:?, itis, the ending, signifying inflammation), inflammation of the pericementum or peridental membrane and the tissues immediately surrounding the tooth. Inflammation of the investing membrane of the roots of the teeth is therefore termed pericementitis, periodontitis, or dental periostitis. Next to hypersemia and inflammation of the pulp, pericementitis is the most prolific cause of toothache. It therefore calls for a careful study of its pathology and its symptoms, that it may with certainty be differen- tiated from other affections which cause odontalgia. Causes. — Pericementitis may be divided into two distinct forms, one dependent upon local causes for its existence, the other upon general or constitutional conditions, and these forms may be either acute or chronic, septic or non-septic, in their character. Local pericementitis is a condition of inflammation of the investing root membrane caused by traumatic injury or septic poisoning. Traumatic pericementitis may be induced in vital teeth by blows, falls, or malocclusion, either from the natural movement of the teeth incident to the loss of supporting neighbors or by fillings which have not been prop- * Dental Pathology, Therapeutics, and Pharmacology, t American System of Dentistry, vol. i. p. 921. 459 460 OPERATIVE DENTISTRY. Fig. 571. eriy shaped to give a perfect occlusion with opposing teeth ; by the press- ure of an ill-fitting partial set of artificial teeth ; by an ill-fitting crown or by an improperly adjusted clasp ; by excessive malleting and Fig. 570. wedging ; by ligatures and rubber-dam clamps ; by the rapid movement of teeth in the operation of regulating ; by the pres- ence of a rubber band used in regulating, and which has been allowed to cut its way towards the apex, as shown in Fig. 570 ; by the irritating presence of salivary calculus upon the roots ; by an imperfect root-filling, or by puncturing the side of the root with drills or reamers. In traumatic pericementitis the inflammatory condition is of an acute diffused character, seemingly involving the whole of the membrane at the same time, but presenting symptoms which, as a rule, are much less severe in their manifestations than those associated with septic conditions. In a majority of cases of traumatic pericementitis the inflammatory symptoms never reach the stage of suppuration and involvement of surrounding tis- sues. In the severer forms of injury, such as blows and falls upon the teeth, accompanied by laceration of the overlying tissues or partial luxa- tion of the teeth, induration and swelling are often very considerable, sometimes ending in suppuration from infection of the injured tissues. Perforation of the lateral wall of the canal often establishes a pericemen- titis which resists all efforts at treat- ment. Injuries, however, which do not cause a break in the continuity of the tissues do not, as a rule, suppurate unless the pyogenic organisms are al- ready in the system and are deposited at the point of injury from the blood- current. Under such circumstances the injured tissues, by reason of their low- ered vital powers of resistance, would furnish a favorable soil for the growth and propagation of the pyogenic organ- isms, and the formation of pus would be the result. Septic pericementitis may be either acute or chronic, and is usually the sequel of inflammation and gangrene of the pulp, the exceptions being such cases as those just mentioned. Septic peri- cementitis always begins as a circum- scribed inflammation, located at the apex of the root of the tooth, occasionally in- volving one or more teeth upon either side of it ; the tissues first involved are those of the apical space, and for this reason it is often spoken of and described as apical pericementitis. Acute apical pericementitis sometimes accompanies pulpitis ; when this dual condition is manifest in double- or multiple-rooted teeth, it is possi- G E J K A, dental pulp and its artery ; B, dentin ; C, tunica propria ; D, enamel ; E, pericementum ; F, cementum ; O, canal in lower jaw ; H, dental artery; J, branch of dental artery supplying pericementum ; A', branch of dental artery supplying tunica propria. (After Black.) DISEASES OF THE PERICEMENTUM. 461 ble for one of the roots to contain a devitalized pulp while the other por- tions are vital ; but when this dual condition occurs in teeth having a single root, another explanation is needed to account for the phenomenon. It seems probable, therefore, that inasmuch as the vessels of both the pulp and the pericementum arise from a common branch located at the apical space (Fig, 571), and the connective tissue which enters the foramen with the vessels and nerve-trunk is continuous with the pericementum at the apical space, the inflammation has spread by continuity of structure. Acute apical pericementitis, however, is not always of septic origin, for it may be the result of chemic irritation from the escharotic action of arsenous acid, zinc chloride, carbolic acid, or other irritating agents which have been applied to the pulp or to the canal and have escaped into the apical space. Or it may be due to the mechanic irritation of portions of filling- material which project beyond the foramen and press upon the apical tissues. Pathology. — Acute apical pericementitis due to septic infection from a gangrenous pul^^ does not differ materially in the pathologic changes which take place in its tissues from those which are observed in any other tissue which may be the seat of a septic inflammation. Irritation at the apex is produced by infection of the apical tissues with the micro-organisms of supjiuration or of their waste products, or with the ptomaines of decomposition produced by the action of the saprophytic organisms upon the gangrenous pulp. At the beginning the irritation produces hypersemia of the vessels of the pericementum, especially near the ajDCx of the root ; this is followed by exudation of the liquor sanguinis and the migration of white blood- corpuscles, and later by proliferation of the connective-tissue cells. The pericementum now becomes thickened, and presents areas of cloudiness. Later as the inflammation progresses this cloudiness may extend over the entire surface of the membrane. At this stage, if the cause of the irritation is removed, resolution takes place and the tissues return to their normal state. Failing in this, the inflammatory process progresses, and the morphologic elements surround- ing the inflamed part — the leucocytes and the embryonic cells formed from the fixed tissue- cells — lose their vitality and are converted into pus- corijuscles, and through the digestive and peptonizing action exerted by the pyogenic organisms upon the intercellular substance of the tissues it is liquefied and idus is formed, resulting in dento-alveolar abscess. Occa- sionally the inflammatory process is conflned to the apex ; at others it becomes diffused over the entire membrane. Symptoms and Diagnosis. — The flrst symptom noticed in acute pericementitis of septic origin is a gnawing, uneasy feeling of tension in and about the tooth, with a desire to bite upon it. This feeling of tension is produced by the hypersemic condition of the blood-vessels of the peri- dental membrane, and is relieved for the time being by forcibly biting upon the tooth. Forcible pressure upon the teeth drives the blood out of the vessels and relieves the tension for a few minutes, but the gnawing feeling and tension again return in a slightly increased form. Lateral per- cussion of the tooth reveals slight tenderness. The tooth now begins to 462 OPERATIVE DENTISTRY. -» feel longer than the others, as though it were raised from the alveolus, and is slightly loose. This is actually the fact, for as the congestion of the blood-vessels goes on the membrane becomes thickened and the tooth is slightly raised from its alveolus. The gum around the tooth becomes swollen and tender, and the free margins assume a red or purple hue. Pain of a deep, dull, constant character will now be present. Lateral per- cussion is j)ainful, and forcibly biting upon the tooth, instead of giving relief, now causes intense pain. The swelling slowly increases and the pain is still deep-seated, but gradually changing to a dull, throbbing character, while the tooth grows more and more sensitive to percussion. The swelling now becomes more defined and palpation will discover a softening at some one point with fluctuation, which indicates the forma- tion of pus, the penetration of the bone, and an early spontaneous evacua- tion of the pus by natural pointing, or it may escape by burrowing along the side of the root, finding an exit at the margin of the gum. The in- tensity of the symptoms will depend somewhat upon the character of the infection and upon the diathesis of the patient. Differential Diagnosis. — It has already been stated that pericemen- titis, next to pulpitis, was the most common cause of toothache. It there- fore becomes important to be able to make a diagnosis between them. At- tention has also been called to the fact that pulpitis and pericementitis may occasionally exist at the same time in an individual tooth having more than one root, but it is not impossible for this dual condition of inflamma- tion to exist in a tooth with a single root. Under such circumstances the shai*p, stinging, lancinating pain of a pulpitis may be present and asso- ciated with soreness to percussion and elevation of the tooth in the alveolus. In a large majority of cases, however, pericementitis is not developed until after the vitality of the pulp has been destroyed and the saiDrophytic germs have begun their work of reducing the gangrenous pulp to its original elements. The ]pain from pulpitis is of a sharp, stinging character, and inclined to be paroxysmal and reflected to various parts of the face, making it often difficult to locate the tooth which is causing the pain. The normal heat sense is also greatly lowered, so that temperatures which can be borne by a healthy tooth become intolerable in one afl'ected with pulpitis. While in pericementitis the pain is always located in the affected tooth, and is of a dull, heavy, gnawing character. The heat sense in pericementitis is raised somewhat above that of the tooth affected with pulpitis. In the early stages of an inflammation cold is soothing, as it contracts the blood-vessels and retards the progress of hypersemia and exudation ; while in the stage of congestion and partial stasis heat is more beneficial, as it tends to pro- mote the movement of the blood, particularly in the congested veins, and thus relieves the tension upon the hyi)ersensitive nerve-fibres of the in- flamed tissues. A rigor and elevation of temperature indicate the forma- tion of pus. Prognosis. — The usual duration of acute septic apical pericementitis is from three days to two weeks. In a majority of these cases the inflamma- DISEASES OF THE PERICEMENTUM. 463 tion ends in suppuration and the formation of a dento-alveolar abscess, occa- sionally they terminate in resolution, while in others the cell proliferation results in the formation of new cement-tissue, — hypercementosis. The latter condition is the result of a continuation of the irritation that de- veloped the acute attack, but which is of a milder type, assuming a sub- acute or chronic form. Local Treatment. — The local treatment of acute pericementitis of either the traumatic or septic form is, first, to remove the cause of the irri- tation if it still exists. This comprehends, in the traumatic variety, the relief of malocclusions, the discarding of ill-fitting plates or crowns and improperly adjusted clasps, the removal of salivary calculus, or of root- fillings which are causing pressure upon the apical space. In the septic variety it means the opening of the pulp-canal and the removal of its decomposing contents, either by chemic means — treatment with sodium dioxide solution— or by mechanic means, in the use of broaches, barbed cleansers, etc., exercising the greatest care not to allow the broach or Donaldson cleanser to pass the apical foramen or to force the septic material into the apical space. Frequent irrigation with antiseptic Fig. 572. Dunn capillary or drop syringe. solutions should accompany the process of cleansing the canals, followed by the application of hydrogen dioxide, either upon a pledget of cotton or by the aid of the Dunn syringe (Fig. 572). After the canals have been thoroughly cleansed, thej^ should be dressed with one of the essential oils or Dr. Black's one-two-three mixture : or, R Oil of cinnamon, 1 part ; Carbolic acid, 2 parts ; Oil of wintergreen, 3 parts ; R Eugenol, 1 part ; Carbolic acid, 2 parts ; Eucalyptol, 3 parts ; or with some other suitable antiseptic. In opening the canals of teeth which are very sore the tooth should be supported with the thumb and index-finger of the left hand while drilling through the overlying dentinal tissue or the filling, as the case may be. Or a ligature may be tied around the cervix of the tooth, the ends being left long enough to extend well beyond the mouth, and traction made upon it, as suggested by Dr. J. Foster Flagg, to counteract the pressure of the 464 OPEEA.TIVE DENTISTRY. drill. The immediate opening of the canals is imperative in all cases where the pulp has died under a filling, otherwise the accumulation of the mephitic gases will force the septic material contained in the pulp-canal into the apical space and establish an acute alveolar abscess. Such teeth do better if left open for from twenty-four to forty-eight hoflrs than they do if dressings are applied. If left open, the gases of decomposition readily escape, while if the opening is closed, they rapidly accumulate and keep up the irritation. Secondly, to secure rest for the tooth by preventing the opposing tooth from occluding with it. This may be done by moulding a piece of base- plate gutta-xDcrcha to the crowns of the lower bicuspid and Fig. 573. molar teeth upon the opposite side of the mouth, or the adjustment of a metal cap, as shown in Fig. 573, so that when the teeth are closed they rest upon the gutta-percha splint or the metal cap. Or, if there are no teeth remain- ing upon the opposite side, a tooth in front or behind the Metal cap. affcctcd One may be utilized for the purpose. Or a hollow rubber crown, made by the S. S. White Company, may be placed ux)on a tooth in a suitable location. A still more simple and ef- ficient method is to dry the morsal surface of two or three teeth upon the same side of the mouth, preferably the lower teeth, and cover them with zinc oxyphosphate cement. The writer prefers Ames's metaloid for this purpose to any other, on account of its great adhesive qualities. After rest has been secured, the third step in the treatment is the ex- hibition of topical remedies for the relief of the pain and -controlling or aborting the inflammatory symptoms. The local congestion may be re- lieved by freely scarifying the gum over the affected tooth, and promoting the bleeding by the free use of warm water. Or counterirritation may be employed by painting the gum with cantharidal collodion or with the following combination of remedies : R Tincture of aconite, Tincture of iodine, Spirits of chloroform, Spirits of camphor, aa f 3 i. M. Darby' s capsicum and sinapin dental plasters will also be found beneficial in deflecting the blood to the surface, if applied to the gum directly over the affected tooth. The hot- water bag applied to the side of the face is often very soothing in the more advanced stage of the inflammation. It should be wrapped in a towel or covered with several thicknesses of flannel, to conserve the heat and to furnish an agreeable surface upon which to rest the face. Constitutional Treatment. — The throbbing pain may often be greatly relieved by the use of a hot foot-bath to which a tablespoonful or two of mustard has been added. This equalizes the circulation hy causing a determination of blood to the lower extremities, and relieves arterial tension in the upper part of the body, and by that process mitigates the pain. A brisk saline laxative is also beneficial in many cases. DISEASES OF THE PERICEMENTUM. 465 In the more severe cases, accompanied with, febrile symptoms, full bounding pulse and high temperature, coated tongue, constipation, head- ache, and chilliness, efforts are still to be made to abort the inflammation. Quinine in doses of from five to ten grains may be administered, or some of the coal-tar derivatives, like pheuacetine or antikamnia, may be em- ployed in five- to ten-grain doses until the excessive rapidity of the pulse is controlled and the pain rendered less severe. If the inflammatory symptoms are not markedly less by bedtime, ten to fifteen grains of Dover's powder may be administered with a hot lemonade or other hot drink, and the patient, after a hot foot-bath, placed in bed and covered with an extra blanket in order to promote copious diaphoresis. Or bromide of potassium, fifteen to twenty-five grains, combined with tincture of veratrum viride, five minims, may be administered, and repeated in four hours if needed. Constipation may be relieved by taking in the morning before breaking the fast a glass of Hunyadi water or one-half ounce of sulphate of magnesia in a glass of water, or a grain of calomel may be adminis- tered at bedtime, omitting the lemonade, and following it in the morning with a Seidlitz powder. Some operators have great faith in the constitutional effect of calcium sulphide in limiting the suppurative process. Its use is, however, some- what empirical, as there is no definite knowledge of its physiologic action upon the tissues. The theory has been advanced, and the results seem to prove the theory, that it has, first., a stimulating effect upon the blood- current and glandular elements of the mucous membrane and the skin ; secondly., this stimulating effect is noticed in the increased movement of the blood-current and in the amount of normal glandular secretions, while it checks that due to venous congestion and blood stasis j thirdly, it is thought to produce H.^S in the system, which has a controlling or restraining influ- ence upon the amseboid movements of the wandering cells or leucocytes. SUBACUTE AND CHRONIC PERICEMENTITIS. These conditions present all of the characteristics of the acute form of the disease, but in a less severe form. The most common cause of subacute and chronic pericementitis is a septic condition of the pulp-canals, sometimes resulting in pericemental soreness only, or in the formation of pus. These forms of pericementitis are usually the sequelae of acute attacks of the affection. They may also occur in teeth in which the pulps have been removed and the canals filled, but this condition is usually found associated wdth crooked roots or con- tractions of the caliber of the canals which have prevented the complete removal of the pulp to the apical foramen ; or they may be caused by sei^tic conditions from a pulp which has died under a filling ; and occasionally they are found associated with apparently sound teeth that have suffered from some traumatic injury which caused death of the pulp, but which for a long period gave no trouble ; or with teeth whose pulp vitality has been lost through the plugging of the artery of supply by a thrombus, and fatty degeneration has taken place in the tissues of the pulp. In a considerable 30 466 OPERATIVE DENTISTRY. number of cases of subacute and chronic pericementitis there is no evidence whatever of the formation of pus, or even of swelling of the overlying gum-tissue. This is true of even some of the septic cases. It would seem, therefore, from this that the character of the septic organisms was less virulent than during the acute attack, or that the tissues are more resistant to the action of the organisms or their waste products, or perhaps both of these suppositions are true, and for that reason the inflammatory j)rocess runs a less vigorous course. Symptoms. — In chronic apical pericementitis the patient usually complains of periodical soreness, which lasts for a day or two, or perhaps for three or four days ; the soreness then disappears to return again after a shorter or longer interval. In some of these cases the gum will be markedly congested, in others no discoverable change in the color of the gum takes place. Percussion is more or less painful, and palpation over the apex of the root often gives evidence of tenderness. The tooth is not sensitive to changes of temperature. Marked sensitiveness to changes of temperature would indicate hyper- sensitive dentin or inflammation of the pulp, and should exclude i^erice- mentitis from the diagnosis. Upon close examination of some of these cases a very slight discharge of pus may be discovered at the cervix of the tooth, and if a fine probe is passed into the opening from which the pus can be pressed, it will follow a sinus or open track which the pus has made for itself at the side of the root down to the apex. Treatment. — Many cases of chronic pericementitis are dependent for their origin upon traumatic injuries like malocclusions due to the natural movement of the teeth towards each other after a supporting neighbor has been lost. The malocclusion may be one in which the pressure upon the tooth is too great, or it may be in a wrong direction, forcing it into an abnormal position. The tooth is often slightly loose and sore to pressure or percussion. Or the malocclusion may be caused by a filling which has not been jDroperly occluded to the morsal surface of the antagonizing tooth. In either case the tooth or the filling should be cut away until a natural or comfortable occlusion has been restored, when, by the aid of the local application of the aconite and iodine preparation to the gum over the apex of the tooth, the soreness and looseness will soon disappear. Devitalized teeth which have had their pulp-canals filled furnish a considerable number of mild septic cases which result in chronic perice- mentitis. This is due sometimes to imperfect sterilization of the dentin, or of fragments of pulp left in tortuous canals and crooked roots ; at others to imperfect methods of cleansing and filling the canals, or of forcing portions of the filling-material beyond the foramen. In all such cases the root- filling should be removed, and the oi^eration of cleansing the canals, sterilization, and filling done over again, as this is the only way in which it is possible to secure restoration of health to the tooth. The difficulties are such sometimes, however, on account of the mal- formation of the roots, that it becomes impossible to completely sterilize the canals and restore the tooth to a healthy condition, even after repeated trials of resterilization and filling. Under such circumstances the extrac- DISEASES OF THE PERICEMENTUM. 467 tion of the tooth is the only way out of the difficnltj'^, and this is to be advised rather than to allow the tooth to remain as a constant source of irritation. GENERAL NON-SEPTIC PERICEMENTITIS. General or constitutional non- septic pericementitis is an inflammation of the pericementum involving a number of teeth at the same time in one or both jaws, and dependent upon certain specific systemic conditions, such as rheumatism and gout, tubercular conditions, scorbutus, diabetes mellitus, and albuminuria, or to the local toxic manifestations of certain drugs like mercury, iodine, and phosphorus, and the preparations of gold, copper, antimony, arsenic, etc. The pathologic changes which take place in non-septic pericementitis due to systemic conditions are in general the same as are found in those cases which are dependent upon local causes for their origin. But the exudations are much more liable to become organized into new tissue, re- sulting in hypercementosis. The tendency of acute local pericementitis is, from the severity of the inflammation, to produce death of the exuded leucocytes and the embryonic cells formed from the fixed tissue-cells — necrobiosis — and the formation of pus. While in certain forms of systemic or general pericementitis the tendency is strongly to the formation of new tissue, through the organization of the escaped leucocytes and the embryonic cells. This tendency is most often noticed in that form of pericementitis due to the specific action of gout and rheumatism. On the other hand, when the inflammation is due to certain other systemic conditions like tuberculosis, scorbutus, diabetes mellitus, albuminuria, and mercurial ptyalism, the tendency is in the direction of necrobiosis and the formation of pus. Bhemnatic and gouty pericementitis is rarely general in its character. Its most frequent manifestations are decidedly local in the sense that only a few teeth are involved at the same time, although occasionally all of the teeth may be the seat of inflammatory symptoms due to these causes. Clinical and x^ost- mortem experience teaches that the materies morbi of these diseases has a predilection for the fibrous structures of the body, especially the synovial membranes, the aponeuroses of muscles, the dura mater, the cardiac tissues, and the periosteal and pericemental membranes. The structure most commonly affected is the synovial membrane, resulting in inflammatory conditions of the joints. It not uncommonly happens, however, that there is associated with the inflammatory phenomena of the joints enlargements of the long bones and nodular formations in other localities, while conditions somewhat analogous are often presented in the pericementum. The predisposing and exciting causes of certain irritative conditions of the pericementum seem to have their origin in the same conditions which bring about the phenomenon of rheumatism and gout, and they have also proved by experience to be amenable, in many cases, to the same specific treatment adopted in these diseases. It is a notable fact, also, that in persons suifering from this form of pericementitis the urine, saliva, and perspiration nearly always give a decidedly acid reaction. Serumal de- 468 OPERATIVE PENTISTRY. posits sometimes form upon the root of the tooth near the apex when there is no connection between the deposit and the mouth. Under such circum- stances suppuration often supervenes, and produces a form of pyorrhoea alveolaris. The pericementum seems to be very susceptible to the irritating effects of an acid condition of the blood, whether from an excess of lactic or uric acid retained in the system or from such acids as are found in sour wines and malt liquors. The habitual use of sour wines and malt liquors by those having the rheumatic and gouty diathesis greatly aggravates these conditions, and some individuals are so susceptible to their irritating influence that a slight indulgence will often precipitate an attack of acute articular rheumatism, of gout, or of pericementitis. General pericementitis of a mild form is often the forerunner of an acute attack of rheumatism or gout ; while, upon the other hand, a general or a local pericementitis, involving a number of teeth in different parts of the mouth, may be the only manifestation or expression of the presence of the rheumatic or gouty diathesis. Congestion and thickening of the pericementum and temporary loosen- ing of the teeth, and occasionally death of the pulp, accompanied by dull, gnawing pains and more or less soreness, are a not infrequent occurrence in attacks of rheumatism and gout. Symptoms and Diagnosis. — In rheumatic and gouty pericemen- titis soreness and pain in the teeth are early symptoms, and generally associated with an acid condition of the salivary secretions, of the perspi- ration, and of the urine ; while it is not at all uncommon to find the indi- vidual at the same time suffering from muscular pains which are unmis- takably rheumatic in character, or from an acute arthritis of one or more joints of the extremities. Sometimes, however, the only manifestations of the rheumatic and gouty conditions are the soreness and painful condi- tion of the teeth and the acid condition of the saliva and the urine. Eheumatic and gouty pericementitis, like rheumatism and gout in gen- eral, may be acute or chronic in their manifestations. The acute form is usually establisl^ed as the result of taking cold or of over-indulgence in the pleasures of the table, and like those general conditions is greatly ag- gravated by bad weather, a low barometer, and excesses in eating and drinking. The chronic form of the disease is the result of repeated attacks of the acute form, and most often terminates in hypercementosis. Soreness of the teeth to pressure, as in mastication, is the first symp- tom of acute rheumatic and gouty pericementitis. This condition is at first relieved by continued pressure, and the individual desires to close the teeth together and keep them in this iDOsition. After a few hours the teeth become painful to such pressure, and constant effort is made to prevent the teeth from coming forcibly in contact. Mastication then becomes very painful or impossible, and liquid food only can be taken. The gums be- come more or less congested and purplish in color, but suppuration rarely takes place except ichere concretions have been formed upon the roots. When the disease is confined to a few teeth in a single location or in different parts of the mouth, they have the feeling of being loose and considerably DISEASES OF THE PERICEMENTUM. 469 elongated. This is due to the congestion and thickening of the i)erice- mentum, which lifts the teeth from their alveoli and makes them loose. Differential Diagnosis. — Difficulty is sometimes experienced in diag- nosing between a rheumatic or gouty pericementitis and an incipient or chronic aj)ical pericementitis due to septic conditions. These difficulties arise from the fact that pulpless teeth are much more liable to become the seat of rheumatic symptoms than normal teeth, consequently, when several devitalized teeth become the seat of pericementitis, it is almost impossible in the early stage to diagnosticate between them except by inference. The fact, however, remains that in a rheumatic pericementitis several teeth are almost invariably affected at the same time, while in septic apical perice- mentitis a single tooth is usually at fault. Should three or four devitalized teeth be in a state of septic apical inflammation at the same time, the diag- nosis could be proved by the absence of the other symptoms which usually accompany an attack of rheumatic pericementitis. The duration of the symptoms will vary from three or four days to as many weeks, depending upon the severity of the attack and the success of the constitutional treatment. Prognosis. — The prognosis in this form of pericementitis is generally good, for the reason that the acute symptoms are usually controlled by systemic treatment. In the chronic form of the disease the prognosis is less favorable, as hypercementosis is the usual sequel, and systemic treat- ment has little or no effect upon the progress of new-tissue formation. Treatment. — The treatment of these forms of pericementitis is largely systemic, and is comprehended in the regular methods employed in general rheumatic and gouty conditions, — viz., the exhibition of such remedies or combination of remedies as have for their base salicylic acid or colchicum, or both, mercurial and iodine compounds, lithia, various mineral waters, hot mineral baths, and Turkish baths. A restricted diet which reduces the quantity of meat consumed and cuts off all game, wine, and malt liquors, is also beneficial. Local treatment in the form of depletion to directly relieve the con- gested condition of the gums, and indirectly of the pericementum, often gives relief after a little time. This may be obtained by scarifying the gums and promoting bleeding by the use of tepid water held in the mouth. Or these symptoms may be relieved by counter-irritation, as already de- scribed upon a preceding page. If suppuration be present, the pockets should be explored for calcic deposits, and if discovered, they should be removed and the pockets treated with dilute sulphuric acid, trichloracetic acid, or other stimulating and antiseptic applications. For further methods of treatment of this form of the disease the reader is referred to the chapter on '^ Pyorrhoea Alveolaris." TUBEECULAE, PERICEMENTITIS. Pericementitis occurring in an individual of tubercular diathesis runs such a peculiar and rapid course that it deserves separate mention. Al- though, strictly speaking, the term as above applied may not be, perhaps, correctly used, it nevertheless serves to describe a condition by no means uncommon, and which sometimes has serious consequences. 470 OPERATIVE DENTISTRY. In using this term it is not intended to imply that the form of peri- cementitis to be described is due to the presence of, or originates in, the tuberculous condition, or that the tubercle bacilli are the cause of the peculiar and rapid course of the disease. In all of the cases which have come under the observation of the writer, the primary cause of the affection was a traumatic injury of the pericemen- tum, produced l:)y either excessive malleting, as in large contouring opera- tions, the rapid movement of the teeth, or a malocclusion. In all of the cases the patient gave unmistakable evidences of having a tuberculous diathesis. It is generally conceded to be a clinical fact that injuries occurring in tubercular subjects are much more prone to end in supi3uration than are like injuries in other persons, and that the inflammatory i3rocess is much more acute than in other individuals. The following case, which is introduced by way of illustration, occurred in the practice of the writer. The patient was a college student for whom he had made two large countour fillings with gold in approximating cavi- ties in the right superior bicuspids. The operations had consumed four hours of time in the preparation of the cavities and inserting and finish- ing the fillings. The teeth were vital, and the hand-mallet was used in condensing the gold. In a few hours after the operation the teeth became very sore and painful, and at the end of twenty-four hours the face was greatly swollen and the gums tumefied, soft, and boggy from the lateral in- cisor of the right side back to and including the second molar. The teeth thus involved were all loose and exceedingly sensitive to pressure or percus- sion. On lancing the gums, which was done in several places, thick creamy pus was discharged in great quantity, and upon irrigating the pus-cavity it was found to be continuous through the whole extent of the inflamed area. The periosteum was also lifted from the external plate of the alveolar pro- cess, but higher up over the bicuspids than the other teeth. The abscess continued to discharge for several weeks, but finally closed without necrosis of the bone. The teeth all became firm in their alveoli and remained vital. Other cases of a similar nature occurring from various injuries in which necrosis of the external alveolar plate resulted from the inflammation might be described, but this is sufficient for the purpose of illustration. SCORBUTIC PERICEMENTITIS. This form of pericementitis is one of the marked symptoms of scurvy. It is the result of long exposure to a cold and damp atmosphere, coarse diet, insufiicient vegetable food, and fatiguing labor. It most frequently occurs among sailors of the Arctic regions, particularly whalers. It is also seen among soldiers and the men of lumber camps. It is not infre- quently seen in our large cities among the very jDOor, who are housed in damp basements and cellars, and whose food-supply is very scanty and of the least nutritious varieties. Occasionally little children under two years of age are victims of the disease, and this is an evidence of malnutrition. Symptoms and Diagnosis. — Scorbutic pericementitis, as a rule, attacks all of the teeth in rapid succession, and is therefore a general DISEASES OF THE PERICEMENTUM. 471 pericementitis. In a typical case of scurvy the teeth are all loose, sore, and painful, making mastication impossible. The gums ai'e swollen and spongy, purplish in color, and bleed easily, while pus exudes around their margins and from the dental alveoli. The breath is fetid and sometimes there is an increased flow of saliva. Associated with the oral symptoms there are certain manifestations of the disease upon the skin in the form of livid spots intermixed with spots of a less vivid color. These spots are SQiall and resemble flea-bites. They sometimes occur in patches or in strips and are usually located at the roots of the hair ; they are scattered over the chest, thighs, arms, and trunk, and are occasionally seen upon the mucous membrane of the mouth and nasal passages. The disease is ac- companied by extreme weakness, general debility, and depression of spirits. Occasionally there is severe pain in the extremities, particularly in the wrists and ankles. In the severer form of the disease, hemor- rhage occurs from the livid spots found upon the skin {purpura hcemor- rhagica), and from the spots found upon the mucous membrane of the mouth and nose. In many of these cases there is a considerable deposit of salivary calculus about the cervices of the teeth. Treatment. — The treatment of scurvy calls for a radical change in the sanitary surroundings of the patient. A generous diet, supplemented with green vegetables and acid fruits, is generally all that is required in the way of general treatment. In the severer cases tonics are called for, like the elixir of calisaya, strychnine and iron, or quinine. The local treatment for the inflammatory conditions of the teeth and gums would be to cleanse the mouth by the use of hydrogen dioxide, re- move all deposits of soft debris and salivary calculus from the teeth, relieve the congestion of the gums by painting them with the tincture of aconite and iodine, equal parts, or by scarifying them with a sharp lancet, and prescribing an antiseptic and astringent mouth lotion. In indolent and ulcerative conditions the gums may be painted with a ten per cent, solu- tion of zinc chloride in water. General x)ericementitis is often a progressive symptom in diabetes mel- litus, Brighfs disease, and locomotor ataxia. The conditions which are pre- sented are similar to those which will be described later under the head of pyorrhoea alveolaris, with the exception that the roots of the teeth when finally exuviated do not usually show any signs of serumal deposits. MERCURIAL PERICEMENTITIS. This form of the disease is due to the constitutional imj)ression of mercury. Mercurial ptyalism with its attendant evils has been so common in the past that almost every practitioner of twenty-five years' experience saw many cases in the early days of his practice. But happily in these later years the use of the drug has been greatly restricted, so that at the present time such cases are rarely seen except in the Southern States. The effects which are produced by mercury upon the general system, and locally in the mouth, depend upon the quantity administered and the susceptibility of the individual to the action of the drug. Children be- tween the ages of five and ten years are peculiarly susceptible. There is, 472 OPERATIVE DENTISTRY. however, a very great difference in the susceptibility of various individ- uals ; in one an ordinary dose of blue pill or of calomel will produce a severe general pericementitis, inflamed gums, profuse salivation, and swollen tongue, while another seems to be almost proof against its action, even in large and repeated doses. Garretson records a case of mercurial poisoning in a child seven years of age in which the administration of three grains of calomel resulted in the loss by necrosis of the left half of the lower jaw. The writer has recorded a case ^ of a woman thirty years of age in which fifteen grains of calomel taken in three-grain doses at bedtime pro- duced necrosis of both jaws, accompanied by extensive sloughing of the gums of the inferior maxilla and of the soft tissues covering the roof of the mouth, swollen tongue, intolerable fetid breath, excessive salivary se- cretion, loosened teeth, and an uncontrollable diarrhoea, the case ending in death from exhaustion. Various other drugs, such as potassium iodide, pilocarpin, the prepara- tions of gold, copper, antimony, arsenic, etc., are capable of producing ptyalism ; and if this condition is maintained for any considerable period, the pericementum becomes involved, resulting in inflammation of this membrane, suppuration, and possible loss of the teeth. All of these drugs are in some degree eliminated from the system by the salivary glands, and during their elimination they seem to perform the functions of active irritants. A moderate degree of salivation may cause a considerable amount of soreness and tenderness about the gums and the roots of the teeth, but this soon subsides, and no permanent injury has been wrought. But if this condition is repeatedly induced or maintained for a considerable period, pathologic changes are established in the pericemen- tum, which permanently injure the organs of mastication and hasten their destruction. Symptoms and Diagnosis. — Pericementitis due to the toxic effect of mercury upon the general system usually involves all of the teeth. The condition generally begins with an increased flow of saliva and a metallic taste in the mouth. Later pericemental irritation is developed, followed by thickening of the membrane and extrusion of the teeth, which be- come loose and painful. Pus is formed in the alveoli and discharged at the margins of the gums. The gums become inflamed, swollen, and tur- gid, and bleed upon the least provocation. The breath is offensive, and the saliva, which is mixed with pus and blood, has the odor of decomposing animal matter. The tongue is swollen and often fills the mouth, pressing upon the teeth, which leave their imprint upon its edges. The secre- tion of the saliva is so great that it constantly drips from the mouth, and in the severer cases the amount may reach several pints in twenty-four hours. The salivary glands, as a result of their excessive secretion of saliva, frequently become swollen and painful. Diarrhoea is often a promi- nent symptom. The excessive flow of saliva distinguishes this form of ptyalism from ^ Injuries and Surgical Diseases of the Face, Mouth, and Jaws, p. 272. DISEASES OF THE PERICEMENTUM. 473 all others, and although it were impossible to obtain a direct history of the administration of mercury, this particular symptom alone would strongly indicate the nature of the affection. Prognosis. — The prognosis in the milder form of the affection is favor- able to a complete recovery of the tissues to a normal condition. In the severer cases the teeth are not only endangered, but the gums, alveolar processes, and even the jaws may be seriously affected. Gangrene and sloughing of the gums, necrosis of the alveolar processes, and loss of the teeth are common sequelae, and, as already indicated, necrosis of the body of the jaw may sometimes be added to the category of evil results which have followed the administration of even small doses of mercury. Fibrous or cicatricial anchylosis of the jaws sometimes follows as a result of slough- ing of the gams and mucous membrane of the cheeks, which upon healing bind the jaws together with cicatricial bands. Treatment. — The treatment of this form of pericementitis must be directed to the systemic condition ; the first step being to cut off the ad- ministration of the drug and hasten its elimination from the system. This may be accomplished by means of potassium iodide, purgative mineral waters, diuretics, and diaphoretics. The diet should be generous and com- posed of the most nutritious food. The local conditions may be treated with solutions of potassium chlorate, silver nitrate or hydrochloric acid, and astringent deodorant mouth- washes. Especial care should be given to the cleanliness of the mouth. Hydrogen dioxide will be found a most efficient remedy for this purpose sprayed into the mouth and between the teeth. CHAPTBE XXIX. DENTO- ALVEOLAE ABSCESS. Definition. — Abscess, from the Latin abscedere,to depart. An abscess is an accumulation of pus in the tissues of the body, re- sulting from a localized inflammation, and which is surrounded by a wall of lymph (formerly termed the pyogenic membrane, from the erroneous notion that it secreted pus). An abscess may also be termed a hollow ulcer. A dento-alveolar abscess is an accumulation of pus within a dental alveo- lus, or associated therewith, and dependent upon a septic inflammation of the tissues of the apical space or the pericementum, the former re- sulting from a gangrenous pulp, the latter from various forms of irritation or injuries resulting in suppurative inflammation. Causes. — Suppurative inflammation always precedes the formation of an abscess, and the presence of pyogenic bacteria is necessary to establish a suppurative inflammation ; hence it may be stated that an abscess is the result of the infection of the tissues with the i^yogenic micro-organisms which produce the destruction of the exuded leucocytes and the cellular elements of the tissues at the point of infection, and the liquefaction of the intercellular substance, thus forming pus. It is possible, however, to produce pus without the agency of micro- organisms, as, for instance, by the injection of croton oil and other violent irritants beneath the skin ; but the pus so formed is aseptic, and if other animals are inoculated with it, it does not produce inflammatory symptoms, while a septic pus produced by the action of the pyogenic or- ganism will invariably cause suppurative inflammation if a sufficient quantity is introduced into the tissues. Exciting Causes. — The exciting causes of dento-alveolar abscess are found in septic conditions resulting from the death of the pulp and fjom certain inflammatory aifections of the pericementum considered in the preceding chapter. The most common exciting causes of dento-alveolar abscess are the organisms of suppuration and of decomposition, — viz., the pyogenic and saprophytic bacteria. These organisms are constantly found in the mouths of even the most cleanly persons, and are an ever-present menace to all operations upon soft tissues which break the continuity of their surface, and the pulps of teeth which have been exposed by caries or by surgical traumatism. The ptomaines or waste products of these organisms, and the mephitic gases formed (hydrogen sulphide, H^S) as the result of the decomposition of the tissues of the pulp, passing through the apical foramen and coming in contact with the tissues of the apical space, cause irritation and a lowered vitality of the tissues as a result of their poisonous effect. The 474 DENTO -ALVEOLAR ABSCESS. 475 inflammation whicli follows, however, is not always of the same character or intensity, the difference in these respects being controlled, seemingly, by certain x^redisposing causes, — viz., the vii'ulence of the organisms, the local resistance or stamina of the tissues, and the general condition of the individual. Predisposing Causes. — The character of a septic inflammation de- pends in great measure upon the virulence of the organisms which have been introduced into the system. This is a well-established law in both pathology and animal toxin therapy, and has been abundantly demon- strated by experiments upon animals and ujjon man, as, for instance, in the treatment of anthrax with the attenuated virus, and of malignant inoperable sarcomas with the toxins of the bacillus prodigiosus and with the streptococcus erysipelatus. The effect of an infection with the pyogenic cocci will always vary with the number of the organisms which have entered the tissues. Watson Cheyne found in his experiments with the proteus vulgaris of Hauser — a bacterium commonly associated with putrefaction — that a dose of one- tenth cubic centimetre of an undiluted culture contained about two hun- dred and fifty million bacteria, and when injected into the muscular tissue of a rabbit quickly proved fatal ; while a dose of one-fortieth cubic centi- metre, containing about fifty-six million, caused very extensive abscesses, and resulted in death of the animal in from six to eight weeks. Doses which contained less than eighteen million very rarely produced any eflect. These experiments demonstrated the fact that the system when in a healthy condition has wonderful resistive power against the organisms of disease. He further demonstrated with cultures of the staphylococcus pyogenes aureus that it was necessary to inject a dose sufficient to include at least one billion cocci into the muscle of a rabbit to produce a speedy fatal result, while a dose containing two hundred and fifty million caused the formation only of a small circumscribed abscess. The staphylococcus pyogenes albus produced the same results, but required somewhat larger doses. Another fact of great interest was discovered by this investigator, — ^viz., that concentration of the septic material in a certain locality was necessary to produce the most marked results. Dividing the dose and injecting it at different times, or in different localities at the same time, did not produce the same results as when it was all injected into a single locality. The tone, resistance, or stamina of the tissues play an important part in the predisposition to infection. Tissues whose vitality or resistive powers have been lowered by traumatism, either accidental or surgical, or by disease, succumb more readily to a septic infection than do tissues in a normal condition. Healthy protoplasm is possessed of great resistive power to the action of disease-producing bacteria, and this is the salvation of the human race. But for this every member of the human family would become diseased, and the race soon swept from the face of the earth. The general condition or tone of the individual is an important factor in the predisposition to infection. Persons who are debilitated from illness, overwork, anxiety, debauchery, and other causes are far more susceptible 476 OPEEATIVE DENTISTRY. to the invasion of patliogenic organisms than are those in robust health. The same is true of individuals who have inherited syphilis and that con- dition generally known as struma. In these cases the evidence of a lack of vital resistive power is often strongly marked, and when children pos- sessing these diatheses are attacked by disease, they more readily succumb than do those children born of healthy parents. In this class of individ- uals all inflammatory conditions of the tissues of the mouth and the teeth run a violent course, and suppurative conditions which involve the periqe- mentum, the periosteum, the alveolar processes, or the body of the jaw are prone to result in phlegmonous conditions of the soft tissues, involvement of the lymphatic glands, and not infrequently in septic intoxication. Certain acquired cachexia} like syphilis and tuberculosis also predispose the individual to a more virulent manifestation of a septic inflammation than in persons of good constitution, for the reason that these diseases markedly lower the power of resistance of the tissues and decrease the phagocytic power of the leucocytes. These predispositions are most pro- nounced in early life, and, as a rule, grow less and less prominent with the advancement of age ; but sometimes they persist throughout the whole lifetime of the subject. Varieties. — Dento-alveolar abscess presents in two forms, — viz., acute and chronic. In the acute form the symptoms are often very severe and sometimes alarming, resulting in extensive necrosis of bone, gangrene and sloughing of soft tissues, acute septicaemia, pyeemia, and death. In the clironic form of the disease the symptoms are of a much milder type, but necrosis of bone, septicaemia, and pyaemia are not unheard-of conditions in connection with chronic alveolar abscess. Dento-alveolar abscess is sometimes described as open or patulous, and blind. An open or patulous abscess is one which has a fistula through the gum or other location, from which the accumulated pus discharges. A blind abscess is one which has no opening, except the pulp- ^^' canal, through which the pus could escape. Blind abscesses are usually of the chronic or subacute variety. Pathology. — When the pyogenic bacteria gain an entrance to the tissues of a living body they accumulate very rapidly, forming a minute colony which by their concentrated action, or that of their chemic product, causes coagulation of the serum and of the contiguous tissue, — "coagulation necrosis," — thus forming a nidus or central point for the development of the process of suppuration. Around this central point, composed shredd sac ^^ uccrotic tissuc and containing a colony of micro-organisms, oriymph-waH the leucocytcs accumulate in great numbers, completely en- of tooth ab- closing it bv forming a wall of lymph, as shown in Fig. 574 scess as met & j & j x ■> to withindento- (the pyogcuic membrane of the older writers). alveolar ab- According to the theory of Metchnikoff, certain cells, known scess. o ^ It as phagocytes, play an important part in limiting the action of the, bacteria. The phagocytes are of two varieties, fixed and free. The fixed phagocytes are the endothelial cells and the fixed connective-tissue cells, while the/ree phagocytes are the wandering cells or leucocytes. It is DENTO ALVEOLAR ABSCESS. 477 claimed that the phagocytes attack the micro-organisms which are found in the tissues and destroy them. These organisms under certain circum- stances are found within the body of phagocytes, and for this reason it has been believed that the phagocytes devour bacteria. This theory has also been advanced by Metchnikoff and others in explanation of immunity to disease. Immunity or susceptibility, it is claimed, depends upon the ability or inability, respectively, of the phagocytes to destroy micro-organ- isms. This theory may be entirely correct, but as yet it is not universally adopted. One of the strongest arguments against it is the fact that infec- tious diseases can be i)roduced by the peculiar poisons or waste products elaborated by the bacteria and without the presence of the organisms which elaborated the peculiar poison. Formation of Pus. — Through the agency of the peptonizing power of the micro-organisms lodged at the point of infection the central mass of dead tissue, formed by the process of coagulation, and the contiguous intercellular substance are liquefied. This process liberates the exuded leucocytes which were entangled in the meshes of the intercellular sub- stance, and they become mixed with the liquefied material and break down into a granular detritus, which, with the dead leucocytes, forms pus. This process continues with greater or less rapidity, according to the char- acter of the inflammation and the diathesis of the individual, the quantity of the pus steadily increasing in amount ; tension of the surrounding tissues results, and both the bony and soft structures are destroyed by molecular necrosis until the surface is reached, following that course which offers the least resistance. This is termed pointing, and through this open- ing the fluid contents of the abscess are discharged. During the process of the formation of the abscess active cell proliferation in the fixed tissue- cells is going on in the outer portion of the wall of leucocytes ; while upon the inside of the abscess-cavity a new tissue is formed, known as granu- lation-tissue, which by its growth repairs the damage caused by the death and liquefaction of the tissues involved in the abscess. This tissue is com- posed chiefly of small, round cells with scanty intercellular substance, but very rich in capillary blood-vessels, each granulation-point being occu- pied by minute capillary loops. Location. — According to the common acceptation of the term, an alveolar abscess is an accumulation of pus located in the apical space, the result of septic inflammation induced by a decomposing gangrenous pulp ; and for various reasons it would seem best to restrict the use of the tei-m to this particular form of dento-alveolar abscess. It is true, however, that abscesses are formed within the dental alveolus which have no connection with a gangrenous pulp ; in fact, they are frequently found in the alveoli of vital teeth, as, for instance, in pyorrhoea alveolaris and inflammatory conditions arising from various forms of irritation and traumatisms of the pericementum. In the formation of a dento-alveolar abscess the pus is at first confined to the apical space, where it is surrounded by bony walls. As the pus accumulates pressure is brought to bear upon the surrounding walls ; this pressure, together with the dissolving or peptonizing action of the bacteria, 478 OPERATIVE DENTISTRY. causes a rapid cell-necrosis and disintegration of the surrounding cancel- lated bone, and a gradually increasing cavity is formed at the apex of the root. The tendency of the accumulated pus, assisted by the pressure within the cavity, is to seek an exit in a direction that offers the least resistance. The external or buccal wall of the alveolar process is the thinnest, and offers the least resistance to the progress of the accumulated pus ; for this reason the abscess usually points upon the buccal aspect of the alveolar process, opposite the apex of the root. Dento-alveolar abscesses point in three distinct ways after penetrating the bony walls : first^ directly through the soft tissues ; secondly^ by sepa- rating the periosteum from the bone and forming a secondary pus-cavity ; tJiirdly, by following the pericementum along the side of the root and discharging at the margin of the gum. Dento-alveolar abscesses which point directly through the gum-tissues are the most common, and rarely present any complications. The second form is often complicated with necrosis of portions of bone, and by pene- trating the external tissues of the face or burrowing downward into the tissues of the neck. For these reasons such an abscess should receive prompt attention, in order that the destructive process may be confined to the narrowest limits and disfiguration and other more serious consequences be prevented. The relations of the roots of the incisor and cuspid teeth to the floor of the nose are such, in many instances, that alveolar abscesses may point through the floor of the nasal fossa and produce a purulent discharge that might readily be mistaken for chronic nasal catarrh. The relations of the roots of the bicuspid and molar teeth to the floor of the antrum are such as to make it even less difficult for an abscess connected with one of these teeth to penetrate the floor of the sinus. Abscesses in connection with the teeth of the lower jaw may penetrate the alveolar process, but fail to penetrate the gum, and by force of gravi- tation and the pressure of the accumulating pus make paths for themselves between the periosteum and the soft tissues, or between the periosteum and the bone, and finally discharge upon the face beneath the chin or the jaw. Or they may burrow through the body of the jaw. Abscesses in relation with the third lower molars often penetrate the external tissues at the angle of the jaw, or they may occasionally burrow downward into the neck, forming large pus-cavities in the submaxillary triangle. The writer has operated upon several cases of this character, from which j)us varying in amount from four ounces to a pint had been removed. In some of these cases the tissues were so infiltrated with the pyogenic cocci that for weeks after the original abscess had healed, and the offending tooth had been re- moved, crop after crop of phlegmonous abscesses appeared in the neigh- borhood, located in the cellular tissue immediately beneath the skin. Another form of dento-alveolar abscess is one which has no external sinus for the discharge of the pus. These cases have been for this reason designated as Nind abscesses. The term is, however, hardly a correct one, for the pus discharges through the pulp-canal, which becomes its sinus, and it is DENTO-ALVEOLAR ABSCESS. 479 therefore not a blind abscess. These abscesses are usually small, and, as a rule, have not been very painful ; in fact, all of the acute symptoms have been greatly modified by reason of the ready exit of the pus from the beginning of the suppurative process. Abscesses which discharge along the side of the root and find exit at the margin of the gum are sometimes confounded with the so-called blind abscess, but in these eases a careful examination will reveal the fact that there is no discharge through the pulp-canal. Many times this form of abscess is associated with pulpless teeth whose roots have been filled, but in which there is sufficient septic irritation to keep up a chronic discharge of pus through the sinus which has been formed by the side of the root. CHKONIC DENTO-ALTEOLAE, ABSCESS. A chronic dento-alveolar abscess is one which has passed through the acute stage, but in which the after-symptoms have been greatly modified. Acute dento-alveolar abscesses rarely heal spontaneously ; there is, how- ever, a partial filling up of the pus-cavity by the growth of the granu- lation-tissue which lines it. But there is usually a sufficient amount of decomposition of tissue and the growth of micro-organisms within the abscess cavity and the pulp-canal to keep up a continuance of the sup- purative process and a discharge of pus. Occasionally a dento-alveolar abscess may X3resent chronic symptoms from the very beginning of the suppurative process, as, for instance, in hlind abscess. In many of these cases no marked inflammatory symptoms have developed at any time, and yet there is often a prolonged and obsti- nate irritation at the apical space and a persistent accumulation of pus, which finds an exit through the pulp-canal. Abscesses which have pointed through the external tissues of the face are nearly always of a chronic type, particularly those which have had their origin in ancient traumatisms, perforation of the cementum, broken instruments within the root- canal, or from an impacted position of a tooth. Symptoms and Diagnosis. — The symptoms of acute dento-alveolar abscess in its early stage are the same as in acute septic apical pericemen- titis. If inflammation of the pericementum of a puli^less tooth with the pulp-chamber open has continued for from twenty-four to thirty-six hours, pus has doubtless been formed. With the formation of pus the symptoms become more aggravated. The gums in the region of the affected tooth assume an inflamed condition ; the pain is of a deep throbbing character, which at times is almost intolerable. With the formation of pus there is often a rigor, or chilly sensations are exxDerienced, lasting for an hour or two. This is followed by an elevation of temperature ; the more severe the rigor the higher the fever will run. The temperature may vary from 101° to 103° or 105° F. , according to the virulence of the infection and the susceptibility of the individual to septic irritation. As soon as the pus penetrates the bony walls of the abscess and escapes into the soft tissues the severity of the pain is abated, but the tissues begin immediately to swell, and the swelling may be so great when the affected tooth is located in the upper jaw, as to close the eye, or when 480 OPEEATIVE DENTISTRY. located in the lower jaw to cause great swelling of tlie neck, especially in the submaxillary, triangle. The cervical lymphatic glands may also become swollen and tender, and sometimes suppuration takes place in them. The pus occasionally collects in great quantity, and under such circumstances it is not uncommon for such abscesses, when located in the upper jaw in con- nection with the incisors and cuspids, to rupture into the nasal cavity, and for the bicuspids and molars to discharge into the antrum of Highmore, or through the external tissues of the face, while those in the lower jaw may rupture through the external tissues of the jaw or burrow down- ward, following the fascia of the neck, and rupture at any point above the clavicle. Cases are on record where abscesses in connection with the lower third molars have burrowed downward and discharged into the larynx and at points upon the chest as low down as the mammary glands. Infection and swelling of the lymphatic glands of the neck is a frequent accompani- ment of alveolar abscesses, while metastatic abscesses have been formed in various parts of the body as a result of the invasion of the blood-current by the organisms of the abscess. Dento-alveolar abscesses which discharge into the nasal fossa have been mistaken for cases of chronic nasal catarrh, while such abscesses discharging into the maxillary sinus are productive of the most troublesome cases of empyema of this sinus. The diagnostic signs of acute dento-alveolar abscess are discoloration of the tooth, no response to the thermal test, showing that the pulp is dead, tenderness to percussion, elongation of the tooth, looseness in its alve- olus, tenderness to palpation over the apex of the root, swelling and inflammation of the gum, and fluctuation at that location where the abscess is about to point. The character of the pain is more intense during the formation of the pus than at any other time, and is relieved as soon as the swelling of the external tissues begins. In the differential diagnosis it must be remembered that a sequestrum of necrosed bone or an impacted tooth would produce symptoms so nearly like those of dento-alveolar abscess as to be readily mistaken for that condi- tion. In fact, sometimes the only way that a differential diagnosis can be made out is by tracing the sinus to the sequestrum or to the impacted tooth. Prognosis. — The prognosis of simple uncomplicated dento-alveolar abscess is generally good if proper antiseptic methods of treatment are instituted. Occasionally, however, no method or amount of treatment will avail to save some of these teeth. In certain individuals the death of the pulp means the speedy loss of the tooth from chronic septic peri- cementitis and resorption of its alveolus. Fortunately these cases are not very common, but when they do present themselves they cause an untold amount of anxiety during the effort to preserve them, and deep chagrin when these efforts prove futile and the tooth has to be extracted. When the alveolar abscess is complicated with necrosis of the alveolar process surrounding the tooth it is commonly lost with the necrosed bone ; but when the external plate alone or the mesial or distal septum only are lost, the tooth may in many instances be retained and restored to health and usefulness. DENTO-ALVEOLAR ABSCESS. 481 When it is complicated with perforation of the floor of tlie nasal cavity or of the maxillary sinus a somewhat serious problem is presented. It would at first thought seem that the only treatment that would be required to cure such cases was to properly sterilize the pulp-canals and to fill them. Such treatment does not, however, always succeed, for the reason that there is very great difficulty experienced in properly sterilizing them, on account of the constant draining of the fluids of the nasal cavity and of the antrum into the canals ; in fact, in some of these cases it is impossible to ever get them in such a condition of dryness as to warrant the introduction of a root-filling. Again, it is not at all uncommon to find the apices of the roots of these teeth more or less eroded ; and when the abscess has become chronic, if they are not eroded they are covered with concretions of calcific matter, which makes it impossible for the roots of these teeth to ever again assume a healthy condition. The prognosis is, therefore, unfavorable, and the sooner such teeth are removed the better. Their extraction often becomes imperative as a means of correct- ing the discharges from the nose and from the maxillary sinuses. When the alveolar abscess is complicated with a sinus ivhich discharges upon the face it becomes a matter of considerable interest to the patient as to whether the offending tooth can be saved and the disfiguration of the face corrected if the tooth be permitted to remain. Such cases do not ordi- narily present any serious difficulties in their treatment. One such case associated with a cuspid tooth, which was referred to the writer by a medical friend, discharged by the side of the nose just below the inner canthus of the right eye, and resisted all efforts to puncture the apical foramen or to force antiseptic remedies through it ; and as no improve- ment could be seen in the case after repeated treatments extending over a period of more than two weeks, it was thought advisable to remove the offending tooth, when, upon extracting it, a steel broach was found in the Tipper fourth of the canal, and projecting beyond the foramen a full half- inch. Comment is unnecessary. The discharges immediately ceased, and the sinus closed in less than a week. Later the discolored tissue was removed by an elliptical incision, the skin loosened from the fascia and brought together with very fine silk sutures ; the wound healed by first intention, and the only scar left was a delicate straight line following the natural line of the face. Dento-alveolar abscess is sometimes complicated with perforation of the cementum. Perforations of the pulp-canal which involve the pericemen- tum may be caused in several ways : First, by caries which has operated from within the pulp-canal ; secondly, the absorptive action of the osteo- clasts which, as a reshlt of inflammation, have attacked the cement-tissue at various locations upon the side of the root and penetrated to the pulp- canal ; and thirdly, by the injudicious use of the reamer or drill in en- larging the pulp-canal preparatory to filling, or forming it to receive a post for an artificial crown. Such cases often present a condition of chronic abscess which may discharge through the pulp-canal, by the side of the root at the margin of the gum, or through a sinus in the external tissues. 31 482 OPERATIVE DENTISTRY. The effect of such a perforation is to establish inflammation of the peri- cementum and sometimes ulceration. Perforations which are the result of caries or absorption are irregular in outline, and the edges are sharp and rough. These conditions present an added source of irritation which aggravates the inflammation already existent and stimulates the growth of granulation-tissue. This new tissue enters the perforation and extends into the pulp-canal, sometimes completely filling it, and by its appearance and hypersensitive condition has misled some of the most careful observers into the belief that they were dealing with an hypertrophied pulp. Under such circumstances the application of arsenic for the devitalization of what appeared to be pulp-tissue might prove exceedingly disastrous. The ut- most care should be exercised in reaching a diagnosis in these cases. Perforations which are the result of a surgical traumatism have well- defined edges, as a rule, and if immediately treated upon scientific prin- ciples will, in a considerable number of cases, respond kindly to such treat- ment and the tooth be finally conserved. But when the case is permitted to run along without proper treatment inflammation of the pericementum follows, and the conditions which have just been described may develop, or chronic suppuration may be established. In those cases located in the lower jaw where the abscesses burrow through the body of the jaw and open upon the face or beneath the chin, or extend into the soft tissues of the submaxillary triangle, or into the deeper tissues of the neck, immediate extraction should be recommended in the former and imperatively demanded in the latter. In the former the prognosis is considered unfavorable, for the reason that in a majority of these cases the apices of the roots will be found more or less eroded as a result of the continued inflammatory conditions. While in the latter the prognosis is considered grave by reason of the tendency to diffuse cel- lulitis and the great danger that acute septicsemia may be developed by the absorption of the ptomaines, or that pysemia may be established by the invasion of the pyogenic organisms or the entrance of pus into the blood- current, and the formation of metastatic abscesses in remote portions of the body. Treatment. — The treatment of acute dento- alveolar abscess often de- mands vigorous constitutional treatment to abort the inflammatory process, to allay the suffering incident to the process of pus formation and the pene- tration of the bone for the escape of the pus, and to control the high tem- perature induced by the severe irritation and the absorption of certain waste products of the micro-organisms. The constitutional measures which are usually employed in the treat- ment of alveolar abscess have already been indicated in the preceding chapter on Pericementitis. Local Treatment. — The treatment of acute alveolar abscess in its early stages, before a fistula has been establisJwd, comprehends, — 1. Efforts to abort the inflammation by the employment of local thera- peutic measures, surgical and medicinal. 2. Limiting, as far as possible, the destruction of tissue by controlling the suppurative process. DENTO-ALVEOLAR ABSCESS. 483 3. The earliest possible evacuation of the pns. 4. The promotion of the healing process. Inasmuch as the primary seat of the infection which establishes the suppurative process in the apical space is the pulp-canal, efibrts should be first directed to gaining an entrance to this seat of infection and thor- oughly removing all infectious material. It is an axiom in general medi- cine and surgery that to cure a disease the cause must first be removed. Having remov^ed, as far as may be, by mechanical means, the gangrenous and putrefying pulp, the second step is to render the canals aseptic by saturating or irrigating them with antiseptic drugs, and thirdly, by local depletion, induced by scarification of the gums in the neighborhood of the affected tooth, to promote bleeding by warm water held in the mouth or by counter-irritation of the gum over the diseased tooth, as indicated in the chapter on Pericementitis. If these measures fail to abort the suppurative process by reason of the escape of the infectious material and pyogenic bacteria into the apical space, it becomes necessary, in order to limit the destruction of tissue, to reach this focus of infection by surgical means. This may be accomplished in some cases through the apical foramen and the pus evacuated through this channel ; but if this is not possible, it may be reached by trephining the alveolar plate, or by the extraction of the tooth. In all cases where the tooth is valuable and the general conditions of the health of the individual do not contraindicate, every effort should be made to save the tooth. But in certain conditions of the system, as in tuberculosis, syphilis, continued fevers, anaemia, general debility, nervous prostration, and pregnancy, the conservation of the tooth is contraindicated, as in all but the latter the vital resistance of the tissues is so reduced that great destruction of tissue is likely to attend all suppurative processes ; while in the latter, if the period of confinement is near, it is imperative that all suppurative condi- tions be abated before parturition sets in, on account of the great danger of septic infection at this period, and the establishment of puerperal fever or acute septicaemia from the presence of suppurative foci in other portions of the body, and the infection being carried in the blood- current. Blind abscesses should be permitted to drain through the pulp -canal for forty-eight hours or longer, in fact, until pericemental irritation ceases, before dressings are applied to the root-canal. In trephining the alveolar plate two methods have been suggested. Dr. Black's method is to perforate the gum- tissue by the escharotic effect of carbolic acid, full strength, carried upon a serrated plugger of suitable size, and api^lied to the gum at the point selected for the perforation, and the instrument gently rotated. As the carbolic acid penetrates the tissue it renders it anaesthetic, while the rotation of the serrated instrument cuts away the tissue which has been destroyed by the escharotic action of the drug. In this way the gum is penetrated without causing pain. A sharp, spear-pointed drill is now substituted for the plugger, and the bony plate perforated in the same comparatively painless manner. The only objection to this method is the necessarily slow procedure, as the instrument cannot 484 OPERATIVE DENTISTRY be advanced more rapidly than the penetration of the carbolic acid renders the tissues anaesthetic. A second method is to inject subgiugivally a two per cent, solution of cocaine hydrochlorate over the root of the affected tooth ; make a triangu- lar flap in the gum, the point towards the crowns of the teeth ; then, with a spear-pointed drill (Fig. 575) or a small trephine (Fig. 576), penetrate Fig. 577. Fig. 576. Spear-pointed drills. IJl Trephines. the alveolar plate at the apical space with the engine-drill (A) or hand- drill (B), as shown in Fig. 577, as suggested by Garretson. By this method the operation may be done entirely without pain, except from the injection of the cocaine solution, which is only momentary. On reaching the apical space, the focus of infection may be broken up and the abscess- cavity irri- gated with suitable warm antiseptic solutions, and the opening in the gum and the alveolar plate kept patulous by the introduction of a few strands of antiseptic silk or cotton. The wound and the abscess- cavity should be irrigated two or three times per day until the inflammatory symptoms are abated, when the case may be treated after the usual manner, and as soon as the conditions are favorable the pulj)- canals should be filled. ''Ubi pus ibi evacuo,'" when there is pus evacuate it, is as wise a surgical rule for to-day in the treatment of acute abscesses as when it was first enunciated centuries ago. The expectant treatment, which has until recent years been the general practice, is quite rai)idly giving way to the more rational method of cutting down upon the seat of suppuration and giving immediate exit to the accumulated pus, as by this method the dis- ease is cut short and much suffering saved the patient. A safe rule to follow in all cases of acute alveolar abscesses which have not yet pointed is to apijly the knife and give immediate exit to the accu- mulated pus, for by so doing great relief is afforded the patient, while the destruction of tissue is thereby limited, and the dangers from general septic infection are greatly reduced. The promotion of healing is accomplished by thorough antisepsis of the DENTO-ALVEOLAR ABSCESS. 485 pulp-canals and the abscess-cavity, and securing rest for the tooth during its restoration to health. In the treatment of abscessed teeth which have discharged into the nasal fossa or the antrum of Highmore, extraction is the only satisfactory method of treatment, while in those which have penetrated the external tissues of the face it is also generally the safest practice, especially in those cases which do not respond to the ordinary methods of treatment, such as sterilization of the pulp-canals, abscess- cavity, and fistulous tract, and the employment of such escharotics as creosote and carbolic acid pumped through them, or drawn through them by the cupping device recommended by Drs. T. M. Hunter* and Burchard-f This device is formed of the ordinary rubber polishing-cup mounted ux^on a mandrel, and used by first moistening the inside of the cup and pressing it over the fistulous opening >. until the air is excluded, when the vacuum which has been created by allowing the cup to assume its natural shape will emi)ty the pus-cavity, and if creosote, carbolic acid, or other fluid substance has been placed in the pulp-canal, it will be drawn through the fistulous tract and appear at its exit. In the treatment of abscesses arising from devitalized or impacted teeth located in the lower jaw which have not pointed, but in which the pus has accumulated in considerable quantities and burrowed downward into the submaxillary and carotid triangles, the immediate extraction of such teeth and the evacuation of the pus by external incision is imi^eratively demanded. In opening such abscesses the incision should be made at the lowest point of the pus-cavity, and, on account of the danger from wounding the important blood-vessels located in these parts, the incision with the bistoury should only be carried through the skin, when, with a pair of hsemostatic snap- forceps with the blades closed, the point may be insinuated between the fibres of the muscles and carried into the abscess, and as they are withdrawn the blades may be oj)ened and the fibres of the muscles still farther separated. By this method of tunnelling the tissues all danger of wounding the blood-vessels is entirely obviated. After the evacuation of the pus the cavity is thoroughly irrigated, a drainage-tube inserted, and the external wound dressed with several layers of absorbent cotton liberally sprinkled with powdered boric acid or iodo- form, and a bandage applied. Of course it is understood that so formidable an operation will require a general anaesthetic and the confinement of the patient to the bed for several days. Chronic Alveolar Abscess. — The treatment of the ordinary chronic alveolar abscesses with fistulous openings should follow the same line of procedure as that just laid down for the treatment of acute abscess with fistulous opening. Abscesses which are associated with perforations of the walls of the root communicating with the pulp-canal are in a very large majority of * Dental Cosmos, vol. xxxiv. p. 82. t Burchard's Dental Pathology, p. 379. 486 OPERATIVE DENTISTRY. instances in a chronic state when presented for treatment. In those cases which are the result of a surgical traumatism of recent date, occurring at any point above the middle of the root (the morsal half), the chances for successful treatment are very good indeed, provided resorption of the root in the immediate neighborhood has not begun. The perforation may be closed in the following manner : after having arrested the hemorrhage with tannin and glycerol or phenol sodique, and the cavity thoroughly sterilized and maintained in that condition during the balance of the operation, a disk of No. 60 gold-foil, or, better, a disk of tin cut from a sheet of No. 4 tin-foil which had been doubled ujjon itself four times, or sixteen thicknesses, may be dipped in chlora-percha and laid over the opening and carefully pressed into place, the canal filled with gutta-percha, and the cavity in the crown sealed with zinc oxyphos- phate. In those cases which are the result of pathologic states the treatment becomes much more difficult. When the pulp- canal is filled with granula- tion-tissue, this can be removed by first applying a local anaesthetic like cocaine or eucaine, which in many instances can be employed cataphori- cally. Or an ethereal solution of chloretone — equal weights of each — may be applied upon a pledget of cotton. As soon as it is thoroughly anaes- thetized it can be removed with a small sharp-pointed lancet, delicate enough to enter the pulp-canal for at least half its depth. After the bleed- ing has been arrested, the cavity may be packed with cotton dipped in powdered boracic acid and sealed with gum sandarach. These dressings should be renewed every day for a week, when the canal may be sterilized and the lower half filled with a gutta-percha point, the perforation covered as just described, and the balance of the cavity filled with gutta-percha. If the first treatment is not successful, try again and again, if the impor- tance of the tooth will warrant it. If, however, after repeated trials the tooth remains tender and irritable, it will be the wiser plan to extract it. The same is true of those perforations which occur at that portion which may be termed the apical half of the root. In these cases gutta-percha is the only reliable material which can be used for closing perfoi^ations in this part of the canal. The uncertainty attending the adjustment of the metal disk to the perforation in such a location, or even adapting a gutta- percha pellet over it that will not produce pressure, is so great that they rarely prove successful. A perforation such as would be made by a drill passing through a curved root is usually so clean cut that it can be readily closed by a pellet of tin-foil or gutta-percha, but the septic material still remains in the curved extremity of the root, where it will become a men- acing source of infection and irritation. It is better, therefore, under such circumstances, to extract the tooth at once rather than to attempt its conservation. In those cases, however, which present an obstinate suppurating condi- tion, which iDcrsists after the most thorough antiseptic treatment of the pulp- canals, the abscess- cavity, and the fistulous tract, radical treatment becomes necessary. This may comprehend, first, the curettement of the fistulous tract and the abscess- cavity ; second, the amputation of the apical end of the DENTO-ALVEOLAR ABSCESS. 487 root in situ ; third, the extraction of the tooth, amputation of the apical end of the root, sealing of the canal, and replantation of the tooth. Curettement of the abscess-cavity and the fistulous tract is often employed to stimulate the healing process in indolent ulcerations and abscesses. The object of this procedure is to change the indolent character of the granu- lating process into one of an active character, and thus promote the heal- ing process. The procedure is as follows : first inject a few minims of a two or four per cent, solution of cocaine hydrochlorate, eucaine, or chloretone into the pus- cavity through the fistulous tract. As soon as the parts have become anaesthetic, which will be in from three to five minutes, slit open the fistula to its base or connection with the abscess- cavity ; enlarge the opening in the alveolar plate sufficiently to admit a good-sized straight spoon exca- vator. Carefully examine the apex of the root for any rough or denuded points, and if none exist the case may be considered as offering a fair chance of being cured. The next step is to thoroughly curette the whole surface of the abscess- cavity with the spoon excavator, after which the debris and blood may be washed away and the cavity packed with a strip of boric acid gauze or carbolized gauze. The root-canal should have been previously sterilized and packed with an antiseptic dressing, or the canal may be permanently filled with gutta-percha. In the opinion of the writer the better plan is to permanently fill the root-canal first, and then at the same sitting, or one arranged a few days later, proceed with the operation of curettement. The after-treatment of the abscess-cavity con- sists of removing the dressing once each day, thorough irrigation with a saturated boric acid solution, two per cent, carbolic acid solution, or with cinnamon- water, and redressing with a strip of gauze. The gauze should be packed lightly so as not to injure the delicate granulation-tissue which usually begins to form immediately after the operation. As the cavity grows smaller less and less gauze will be required, and finally it may be left out altogether and the external opening allowed to close. Irrigation, however, must be kept up until the wound is entirely healed. Trequent use of the irrigating fluid should be recommended as a mouth-wash, and the patient instructed to use it every two hours during the day and once or twice during the night as a means of controlling the septic condition of the mouth. If, however, upon examining the apex of the root it is found to be de- nuded and roughened, or covered with calcific deposits, it will be necessary to amputate the diseased portion of the apex. Amputation of the Apex in Situ. — Before undertaking this opera- tion the pulp-canal should be thoroughly sterilized and filled with gutta- percha, and the crown-cavity protected with a filling of zinc oxyphosphate. The fistula is then slit open with a small bistoury down to the apex of the root, the edges of the incision held away, and a section of the alveolar plate removed with the trephine in the dental engine sufSciently large to thoroughly expose the apex of the root, or a large fissure-bur may be used for the same purpose, and the opening in the alveolar plate en- larged by sweeping it around the edges. Hemorrhage may be controlled OPERATIVE DENTISTRY. by packing the wound with cotton saturated with phenol sodique or tannin in glycerol. The apex of the root, after the hemorrhage has ceased, can be readily seen through the opening. The eroded portion should now be amputated with a small, sharp fissure-bur, revolved at high speed with the dental engine. The edges of the stump can be smoothed with a fine finish- ing-bur, or with a sharp excavator or scaler. The cavity should next be thoroughly irrigated, all debris and blood-clots removed, and the cavity packed with a strip of gauze and powdered boric acid. The edges of the incision may be brought together at the upper portion and maintained in position by one or two sterilized horse-hair sutures, the end of the gauze being left at the most dependent portion of the incision, where it may be grasped and removed after twenty-four to forty-eight hours, according as the circumstances of the case may indicate. Meanwhile the moutli must be frequently irrigated with a suitable antiseptic lotion. At the end of a couple of days the dressing is removed, the cavity thoroughly irrigated with antiseptic solutions, and the patient instructed to keep the mouth clean by the frequent use of the antiseptic mouth- wash which has been selected. Teeth which have been treated after this method should not be filled with gold for several months after the operation. A fair per cent, of the cases of amputation in situ prove successful, but the writer is of the opinion that the more heroic operation of extraction and replantation (see following chapter) gives a larger percentage of cures in obstinate cases of alveolar abscess than the preceding method of operation. Alveolar Abscess associated with Deciduous Teeth. — Little chil- dren are often great sufferers from alveolar abscesses associated with their temporary teeth. If the child is timid and greatly afraid of being hurt, the difficulties presented by this condition render the duty of the operator to relieve the little sufferer as quickly as possible a somewhat arduous task. Patience, gentleness, and kindness, however, backed by a little firm- ness, will usually overcome the timidity of the child, and in large measure banish the fear of being hurt, so that it becomes possible to do all that is necessary to give the desired relief. The suppurative process occurring in children is never so severe as in adults, as the tissues of children are soft and break down very readily when subjected to inflammatory processes. For this reason the time con- sumed by the pus in finding its way through the gum is much less than in the adult. And although the pulse and the temperature may run high during the inflammatory process, and the swelling and congestion of the tissues be very considerable, the suffering is not so great as in adults. The treatment of these cases does not differ from that already indi- cated. Immediate relief may usually be obtained by opening the abscess by an incision in the gum. This may be done with so little pain to the child, if the bistoury with which the incision is to be made has a keen edge, and the attention of the child is diverted to some. pleasing subject when the incision is made, as to hardly attract its notice. When all is over the child usually expresses surprise that it hurt so little. With chil- DENTO-ALVEOLAE ABSCESS. 489 dren who are unmanageable it becomes necessary to use a general anaes- tlietic, and under certain circumstances it is best to extract the tooth rather than to attempt its conservation. A very large percentage of jDulpless temporary teeth can be rendered healthy and useful so long as nature requires their service for the purpose of mastication by thorough sterilization of the pulp-canals and filling them with gutta-percha. Dr. W. H. White a few years ago introduced a new material for filling root-canals in children's teeth particularly, — viz., balsam del deserto, which it is claimed does not in the least interfere with the resorptive i^rocess of the roots of these teeth in their exuviation. It is especially useful in filling abnormally large canals. Occasionally a case will be presented in which root-fillings are not tolerated by the tissues. Such teeth should be extracted at once, as re- peated inflammation and the formation of abscesses ' are liable to cause injury to the advancing tooth. Chronic alveolar abscesses are prone to cause swelling of, and some- times metastatic abscesses in, the cervical lymphatic glands of children of the strumous or tuberculous diathesis. Under such circumstances the immediate extraction of these teeth is imperatively demanded. Constitutional treatment is also demanded in these cases for the build- ing up of the bodily vigor. Much can be done for these children by giving them an abundance of out-door life and plenty of wholesome, nutritious food. Sometimes di^ugs are indicated, in the form of cod-liver oil, iron, arsenic, beef-peptones, the bitter tonics, etc., but best of all is sunlight, pure air, plenty of exercise, and the institution of a scrupulous hygienic condition of the mouth. CHAPTEE XXX. REPLANTATION OF THE TEETH. Definition. — Eeplantation, from the Latin replantare, to plant again. Eeimplantation, from the Latin reimplanto, to implant again. The operation of replantation or reimplantation of teeth is the replacing of a tooth in the alveolus from whence it had been removed by accident or by design. Eeplantation is practised at the present time for three conditions : First. — When a tooth has been dislodged by an accidental traumatism, such as might result from a fall or a blow. Second. — When a tooth has been removed as a result of an accidental surgical traumatism, such as the dislodgement of a tooth by the mouth- prop or mouth-gag during the administration of a general anoesthetic pre- paratory to the extraction of a tooth, or the slipping of the forceps in the extraction of a tooth, which causes the dislodgement of its neighbor or one in the opposite jaw. Third. — When a tooth is the subject of a persistent alveolar abscess which does not respond to the ordinary methods of treatment. The degree of success which attends the replantation of teeth depends upon the presence and healthful condition of the pericementum, the length of time that the tooth has been removed from its alveolus, the physical condition of the patient at the time of the operation, the immo- bility of the tooth during the process of forming its new attachments, and the hygienic condition of the mouth. The discussion of the^rs^ and second conditions will be reserved for the chapter on '' Dislocation of the Teeth." The treatment of persistent alveolar abscess by extraction and re- plantation is generally practised as a dernier ressort when all other methods have failed. Obstinate alveolar abscesses are usually caused by a crooked root, an abnormally small root-canal which makes it impossible to remove or render innocuous the retained septic pulp -material, or it is caused by perfora- tions of the root made in attempts to open small root-canals, calcareous deposits upon the apex of the apical end of the root, or erosion of the apical end of the root, which is accompanied by a more or less i)ersistent discharge of pus, either through the external or internal plate of the alveolar process or through the alveolus at the neck of the tooth. Occasionally cases will be found in which no discharges are present, but instead a chronic induration of the surrounding tissues ; or, as in the superior teeth, the discharges may find their way into the antrum of High- more or the anterior nasal passages, and possibly mislead the operator into 490 REPLANTATION OF THE TEETH. 491 the belief that he has a case of empyema of the antrum or of ozsena to deal with.* These teeth are usually sooner or later condemned as worthless mem- bers of the economy, and are removed. Many of these teeth with suitable treatment may be rendered healthy and useful for an indefinite period. Replantation is only admissible in the anterior teeth, including the bicuspids. The molars are capable of being replanted only in exceptional cases when there is fusion of the roots and they assume a conical form, and occasionally a lower molar when the roots are perpendicular to the crown. It will be generally conceded that attempts to cure such cases as those just mentioned by the ordinary methods usually prove unsuccessful, and that eventually the teeth are lost. This results from the fact that such operations are largely, perforce, only guesswork. If the root is curved at a more or less acute angle it is difficult to follow the canal with the broach or Donaldson bristle, and many times quite impossible, or if the canal is abnormally small, the finest Donaldson bristle may not enter it at all. Eeaming the canal is unsafe, and under these conditions the various anti- septic fluids and liquid filling- materials are unsatisfactory because they do not always penetrate to the end of the canal, and consequently septic material remains in the pulp -canal and keeps up a constant irritation. In cases of erosion of the apical end of the root, amputation of this portion in situ is frequently unsuccessful in curing the disease owing to the difficulties in smoothing the stump and perfectly filling the apical foramen. The same may be said of attempts to plug perforations in the sides of the root. Roughened surfaces and foreign substances are not kindly borne by the tissues which surround the roots of the teeth ; it is therefore imperative that all such hinderances to a return to the normal condition be reduced to a minimum. For these reasons it would seem preferable to extract and replant such teeth if they do not speedily prove amenable to treatment by the usual methods ; for, with the tooth in the hand, the root can be minutely inspected, and any eroded portion amputated and the surfaces finely polished. The pulp-canal can be reamed out and cleansed without the fear of perforating its sides, the canal filled and the ajDical foramen or a perforation plugged with gold and carefully finished, and the whole thor- oughly sterilized. ISTone of these operations are possible with the same degree of perfection while the tooth is in situ ; they must, perforce, be more or less imperfect, and just in that degree will they produce irritation and the more serious inflammatory processes. The question might very properly be asked, Are the operations of re- plantation and transplantation of freshly extracted teeth having the peri- cementum attached founded upon physiologic law and sound surgical principles ? The answer is. Yes ; quite as much so as are the operations of skin and bone grafting, and no one condemns these. Union with the * Dental Cosmos, vol. xxxiv. p. 464. 492 OPERATIVE DENTISTEY. tissues witli wliicli they are placed in contact is the result of the same vital I)rocesses ; the surgical conditions are nearly identical in each of them, and success is as certain in the one as in the other, provided the same aseptic conditions can be maintained until union is complete. The failure of replanted teeth to unite with their alveoli is much less common than with transplanted teeth ; at least, the personal observation of the writer bears out this statement. The immediate cause of failure is usually suppurative inflammation, induced either by mobility of the tooth, which constantly breaks up the attachment of the plastic exudate, or septic conditions of the tooth or of its alveolus at the time of the operation, or inoculation afterwards from a septic condition of the mouth. The failures which occur later — viz., after attachment has taken place — are more difficult to understand. In these cases the surfaces of the roots are attacked by the osteoclasts, and gradually honey-combed or masses of pericemental tissue and dentin are dissolved at various locations about the apex, leaving large cavernous excavations with sharp edges. Suppuration accompanies or follows the work of the osteoclasts ; the tooth becomes loose, and is sooner or later expelled from the jaw as a foreign substance. In explanation the writer would venture the oxiinion that these phenom- ena are due to irritation induced by septic conditions resulting from decom- position of the organic material contained in the dentine, and that in the form of a gas or effluvium it penetrates the cementum, and coming in contact with the pericementum and surrounding tissues, sets up this retro- grade metamorjDhosis. There are certain individuals for whom it would not be wise to under- take this operation, — viz., those suffering from general anaemia, tubercu- losis, and syphilis. Such individuals are never good subjects for surgical operations, as their tissues are very irritable, do not, as a rule, heal readily, and are prone to suppuration ; consequently replantation, trans- plantation, and implantation, if performed upon such persons, are likely to prove unsuccessful. Many of the failures from these operations have been associated with one or the other of these diseases. Great care should therefore be exer- cised in the selection of the cases upon which to operate. Carelessness in this regard can only result in failure. Of the more than forty operations of this character which it has been the privilege of the writer to perform, it has been thus far his misfortune to record only a single failure, although they have comprised all grades and durations of the disease, several of very long standing, ranging from five to fifteen years. The character of the union which takes place between the root of the replanted tooth and its alveolus has not so far been positively demon- strated. The writer therefore feels that he may o£fer a few thoughts which may tend towards an elucidation of this question. Applying the methods used in physical diagnosis to these cases, we find that percussion gives the most marked signs. Taking the percussion note of normal teeth, produced by striking the tooth with a steel instrument, as the standard of pitch, we find that as EEPLANTATION OF THE TEETH. 493 inflammatory conditious of tlie alveolus advance the percussion note be- comes lower and duller, while, on the other hand, as these symptoms sub- side the note assumes a clearer and higher pitch. This lowering of the tone is doubtless the result of a thickening of the pericemental membrane and its increased vascularity. The percussion note given by a large per- centage of replanted teeth a few months after the operation, or when union is complete, is much clearer and higher pitched than that of the adjoining teeth. This is more noticeable in the superior than in the inferior teeth, on account of the greater resonance of the superior maxillae. These facts would seem to indicate a bony union in these cases between the root and its alveolus. It would also seem probable that the locations at which this anchylosis would most likely occur would be where the pericementum had been destroyed or the cement- tissue partially removed ; and there seems no good reason why under these conditions reunion may not take place in a some- what similar manner to that which occurs in fractured bones. In some cases the percussion note is normal, this would indicate a nor- mal reunion of the pericementum with the alveolus ; but when the percus- sion note is lower and duller, it would be certain evidence of an indurated pericementum or other inflammatory symptoms. To insure success in these oi:)erations the following suggestions should be observed : 1. Exclude anaemic, tubercular, and syphilitic cases. 2. Secure thorough aseptic conditions of the surfaces of the root and pulp-canal by washing and immersing in bichloride of mercury solution, 1 to 500 of water. 3. Amputate and smooth all eroded surfaces, but sacrifice as little of the pericementum as possible. This is very important. 4. Hermetically seal the pulp-canal and apical foramen, and any per- forations that may exist, with gold fillings. 5. Curette the abscess-cavity, remove the blood- clot from the alveolus, and wash both with the bichloride of mercury solution before replanting the tooth. This is the only treatment of the abscess-cavity and of the alveolus that will be required. 6. Secure immobility of the tooth by a ligature or an interdental splint until union has taken place. An impression of the teeth of that part of the jaw to be operated upon should be taken before the tooth is extracted, and a splint of gold made to include one or two teeth ujDon either side of it. After the tooth has been replanted, the splint is applied and secured in position with zinc oxyphosphate cement, and allowed to remain for from four to six weeks. CHAPTEE XXXL TRANSPLANTATION AND IMPLANTATION OF THE TEETH. Definition. — Transplantation (Latin, trans, across ; plantare, to plant), the operation of grafting tissue from one part of the body to another part of the same body, or from the body of one individual to that of another. The transplantation of teeth is the operation of transferring a tooth from one alveolus in the mouth of an individual to another alveolus in the same mouth, or of transferring a tooth from the mouth of one individual to that of another. The operation of transplanting teeth was, during the days of John Hunter, much more extensively practised than it is at the present day. The study of the literature of that period and of the intervening years shows that as far back as 1783 the operation was falling into disuse, and in 1810 it was referred to as being consigned to oblivion. The reasons which were assigned for giving up the operation were (1) the great danger of transmitting specific diseases- like syphilis, (2) the frequent occurrence of alveolar abscess, (3) the loss of the tooth after a few years from loosening or resorption of its root, and (4) objections were raised to the operation on moral grounds, as the poor sold their teeth to the rich for a price. During the last two decades the operation has been revived, and upon the whole has given somewhat better results than those recorded a hundred years ago. The teeth which are used are usually sound teeth or healthy roots that have been removed in the operation of regulating the teeth or to make room for an artificial denture. The introduction of antiseptic methods in operative surgery has made itx)0ssible to entirely prevent the inflammatory symptoms and the formation of alveolar abscesses which were before this time so common as a sequel of the operation. The danger of transmitting specific diseases has, however, not been overcome, although no doubt greater care is exercised in the selection of the teeth that are to be used for transplanting by inquiring more carefully into the history and x)hysical condition of the individual from whose mouth the tooth was taken. One case has, nevertheless, been reported recently in which syphilis was said to have been transmitted by the transplantation of a tooth taken from the mouth of a syphilitic subject. The tendency to ultimate loosening of the tooth and resorption of its root after a few years remains the same, and there seems to be no way to prevent these untoward results. Teeth which have been treated by the most complete aseptic methods are equally liable to be lost by these morbid conditions as those which had not been so treated. Eeplanted teeth and teeth transplanted from one alveolus to another of the same mouth give better results, in the observation and experience of the writer, than do teeth transplanted from the mouth of one indivdual to that of another. 494 TRANSPLANTATION AND IMPLANTATION OF THE TEETH. 495 The operation is applicable only to the ten anterior or single-rooted teeth. It will be seen, therefore, that the operation is confined to rather narrow limitations, the confines of which cannot, with any assurance of success, be overstepped. The same general conditions that promote success or failure in replanted teeth are operative in transplanted teeth, — viz., the presence of healthful or morbid condition of the pericementum, the length of time that the tooth has been removed from its alveolus, the physical condition of the patient at the time of the operation, the hygienic or non-hygienic con- dition of the mouth, the adaptability or non-adaptability of the tooth to its new alveolus, the healthful or morbid condition of the new alveolus, and the mobility or immobility of the tooth during the formation of its new attachment. The most favorable period in which to perform the operation of trans- plantation is during youth and early adult life, although it may be suc- cessfully performed at any period provided the patient is in vigorous health. In the selection of a tooth for transplantation, one should be chosen which is as near as possible of the same age as the tooth which is to be replaced. Teeth which are younger than the one to be replaced are, how- ever, more likely to form a healthy union with the new alveolus than those which are older. The practice of selecting teeth which have been extracted for a con- siderable time, where nothing is known of their history or of the physical condition of the patient from whom they were taken, should be severely criticised for the reasons already mentioned. Too much care cannot be exercised in this direction. When a suitable sound, fresh tooth cannot be secured, a tooth with a carious crown but healthy root may be selected, and an artificial crown of proper color and form grafted upon the root by any of the various methods of crowning. It is better, also, in selecting the tooth, to choose one with a slightly larger, rather than a smaller, root than the tooth to be replaced, as it is an easy matter with suitable burs and drills to enlarge, deepen, or change the shape of the alveolus to fit the tooth. When the root is too small to fit the alveolus immobility cannot be secured, and as a consequence a good union does not take place. The best results are obtained by completing the operation at the same sit- ting. The tooth to be replaced should first be extracted, care being exercised not to fracture the alveolus or unnecessarily wound the gum. The tooth to be replanted is next extracted, the pulp-canal opened, the pulj) extirpated, the canal filled with gutta-percha, and the apical foramen and the opening in the crown plugged with gold. The whole operation should be performed according to the strictest aseptic methods. (See preparation of the tooth for replantation, in preceding chapter.) The alveolus should then be shaped to receive the new tooth, the alveolus and tooth thoroughly washed with a solution of mercuric bi- chloride, 1 to 1000 of water. The tooth may now be placed in position and retained, if necessary, with a ligature, an impression taken of this 496 • OPERATIVE DENTISTRY. section of the mouth, and a metal splint constructed which will cover the transplanted tooth and one upon either side of it, and cemented in place with zinc oxy phosphate. The onlj^ after-treatment that is necessary is that comprehended in a thoroughly clean condition of the mouth, secured by careful brushing and the frequent use of antiseptic solutions. The splint may be permitted to remain in position for a period ranging from four to twelve weeks. Method of Union. — The union which takes place between the alve- olus and a fresh tooth in which the pericementum is intact over the whole surface of the root would seem to be by a normal process, like that which takes place between these tissues in a tooth which has been dislocated by accident and immediately replanted. In those cases, however, in which the pericementum has been removed in part by shortening of the root or by disease the union seems in some cases to be bony, in others fibrous. Mitscherlich transplanted a tooth in a dog, and after six weeks ex- amined it, and found that a considerable portion of the pericementum had disappeared, that resorption had taken place at several locations, followed by calcification of the osteoclasts and the formation of new tissue within the spaces or cavities formed by the resorptive process. This new-formed tissue was continuous with the bone of the alveolus, and held the tooth firmly within its alveolus. The notion that has been held by some operators that the pericementum of the tooth after it has been extracted for some considerable time and had become dried and dead was after transplantation revivified has no foundation in fact, and is directly opposed to all physiologic law. The attachment which occurs between such teeth and the alveolus is, in all probability, a semi-mechanical one, such as was demonstrated by Mitscher- lich in his experiment upon the dog. Prognosis. — Eesorption of the roots of transplanted teeth usually occurs at an earlier or later period, ranging from a few months to four or five years, although in exceptional cases they have remained successfal for a considerably longer period ; the late Dr. Morrison reported cases which were successful after eleven years. IMPLANTATION OF TEETH. Definition. — Implantation (Latin, invplantatio, from in, in, and plan- tare, to set), the act of setting in. Applied to surgery it may be the engrafting of epidermis from the skin of one person upon the body of another, the surgical repair of a wounded intestine by uniting the divided ends, or the setting or transplanting of a tooth taken from the jaw of one person and inserted into an artificial alveolus made in the jaw of another. Implantation of teeth is an operation of modern times, suggested by Dr. Younger, of San Francisco, California, and when first introduced attracted considerable attention from the profession. Many operations were made with little regard to the physical condition of the persons operated upon or to the hygienic conditions of the mouth. Teeth were TEANSPLANTATIOJS" AND IMPLANTATION OF THE TEETH. 497 implanted for iDersons suffering with syphilis, tuberculosis, and other con- stitutional diseases, and certain vicious habits like alcoholic intemperance, which have a tendency to lower the recuperative powers of the tissues and favor the suppurative process. Consequently there were very many more failures than would in all j^robability have occurred had the cases selected for the operation been more carefully chosen. The only persons upon whom the operation should be performed are those who are in vigorous health, whose occupations do not call for an un- usual expenditure of nerve force, and who are accustomed to keeping their mouths in the very best hygienic condition. Requirements for the Operation. — The successful performance of the operation of implantation requires u]3on the part of the operator an intimate knowledge of the anatomy of the parts involved and their rela- tionship to other parts. It must be constantly borne in mind that after resorption of the alveolar process has taken place the depth of the bone is very much less than before the tooth had been extracted. In some cases the bone which intervenes between the apices of the roots and the nasal fossa or the antrum of Highmore is extremely thin, often not more than one-fourth to three-eighths of an inch in thickness, while in extreme cases it rarely exceeds half an inch in thickness. It is necessary, therefore, to exercise great care, in forming the artificial alveolus in the upper jaw, not to i3enetrate the nasal fossa or the antrum of Highmore, or to encroach upon the anterior palatine canal, which carries the anterior palatine artery, vein, and nerve, when forming an alveolus for a central incisor. When resorption of the alveolar process has been very considerable, it is often exceedingly difficult to so form the artificial alveolus as to give the tooth its right position and inclination in the arch and preserve a bony wall for the labial surface of the alveolus. This diffi- culty is more often encountered in the region of the central and lateral incisors than in that of the cuspids. Should the operator be so unfortunate as to penetrate the nasal fossa or the maxillary sinus, extreme care must be exercised not to infect the sinus. To guard against infection the artificial alveolus should be immediately plugged with a single strip of antiseptic gauze, which should remain until the tooth is ready to be inserted into its new alveolus. To guard against the possibility of the apex of the tooth passing into the nasal fossa or the antrum under these circumstances, the depth of the bony socket should be measured and the root shortened to correspond with its depth. The preparation of the tooth selected for implantation should be the same as for a tooth which is to be replanted or transplanted. The next step in the preparation for the operation is the construction of a metal splint to secure the tooth in position while union is taking place. This is done by taking an impression of the space to be occupied by the implanted tooth and the teeth upon either side of it. A plaster cast is made from this impression, a bite is taken, and the whole placed in an articulator. A suitable-sized socket is then drilled in the plaster cast, the root of the tooth adjusted therein, and the proper occlusion secured. 32 498 OPERATIVE DENTISTRY. From the plaster cast, with the tooth retained in it, a die is made and the metal splint swaged over it. The tooth is then thoroughly cleansed and placed in a suitable disin- fecting solution, 1 to 1000 bichloride, or a saturated boric acid solution, and kept at a temperature of 100° to 110° F. until the artificial alveolus has been made in the jaw. Method of Operation. — The first step in the operation is to make an incision in the gum- tissue down to the bone. The form of this incision will depend largely upon the individual preference of Fig. 578. the operator, the main object being to conserve as much of the firm tissue as possible. Some operators employ a circular incision made with the EoUin circu- lar knives (Fig. 578), others i^refer a crucial incision (X), which makes four flaps ; others an incision in form of the letter H, which makes two flaps ; while still others prefer to employ a U-like or staple-like ( U ) incision, which forms a single flap. In the X or crucial incision the centre of the cross should correspond with the centre of the alveolar border, and the flaps are to be turned back out of the way of the instruments which are used to form the Circular knives. socket in the bone. In the letter H incision the upright lines of the incision are made across the alveolar border, close to the approximal sur- faces of .the teeth upon the mesial and distal sides of the space to be filled by the implanted tooth, while the bar or horizontal incision should con- nect the upright incisions through the centre of the alveolar border. In the U-like or staj^le-like (U) incision the upright incisions are made across the alveolar border, close to the approximating teeth, while the curved or the straight incision made to connect the upright incisions are to be made at the lingual border of the alveolus. The incisions having been made, the next step in the operation is to lift the flaps from the bone, and in doing this care should be taken to get be- neath the periosteum, so that this membrane will be left adherent to the gum-tissue, as by so doing the periosteal layer of the flaps will, when it comes in contact with the root of the imjplanted tooth, assist in forming a new alveolar border. Delicate periosteotomes for this purpose may be made from selected enamel chisels by rounding the cutting edges. The flaps, having been lifted from the bone, should be held out of the way by a delicate spring tenaculum-speculum during the forming of the new alveolus. The greatest care should be taken not to bruise the edges of the flaps, otherwise inflammation and sloughing of the borders or of the entire flap may follow. Various instruments have been suggested for the purpose of forming the socket in the bone. The first instruments made for this purpose were the Younger trephines ; these have since been improved by Dr. W. W. Walker, of 'New York, and are now made with a set-screw collar which slides upon the shaft of the instrument (Fig. 579), and can be set at any TRANSPLANTATION AND IMPLANTATION OF THE TEETH. 499 point to correspond with the desired depth of the alveolus. Instruments of this character, however, need to be supplemented with others which cut ui3on the side, as with the trephine alone the alveolus cannot be x^rop- erly shaped or the core removed. The reamers designed by Dr. Younger (Fig. 580) for this purpose have a serious disadvantage in that they are inclined to clog. The spiral knives of Dr. Eollin (Fig. 581) are a decided improvement over the Younger reamers, in that they are not so liable to clog and cut much more rapidly. The combination drill and reamer instruments (Fig. 582) of Dr. Ottolengui, of New York, are the best of this series of instruments, in that they cut very freely and rapidly, do not clog, and are provided with a safety collar that can be set to suit any depth of alveolus that it may be desired to make. Fig. 581. Fig. 579. Fig. 580. Fig. 582. Younger- Walker trephines. Younger reamers. The Ottofy spiral crib-knife is also a valuable instrument, as it cuts with great rapidity and does not clog. The spiral osteotomes of Dr. M. H. Cryer, of Philadelphia, are designed for the same purpose, and are the most rapid-cutting instrument of the series, and if x^ermitted to run freely they do not clog. Long-shanked, coarse-cut engine-burs are also useful for making any slight changes that may be required in the shape or depth of the alveolus. During the process of forming the alveolus the parts should be fre- quently irrigated with an antiseptic solution, preferably a saturated solu- tion of boric acid in water or the Thiersch solution. After the proper depth has been reached, and during the x>rogress of shaping the alveolus, the tooth should from time to time be inserted until the proper adjust- ment to the socket and the position in the arch has been secured. Another important feature of the operation is to secure a proper occlusion, but it is better to have the tooth a trifle too short than by ever so small a fraction too long, for if the pressure of the jaws comes entirely upon the implanted tooth, inflammatioii is liable to follow as a consequence of the mechanical irritation. 500 OPERATIVE DENTISTRY. As soon as hemorrhage has ceased, the month and the socket should be irrigated with a 1 to 1000 mercuric bichloride solution, the tooth washed in the same solution and then placed in position, the parts dried, and the splint cemented in place. As soon as the cement has set the surplus should be removed, the parts again irrigated with the bichloride solution, and the edges of the gum flap nicely adjusted to the cervix of the tooth. If the corners of the flaps are inclined to fall away — evert — from the cervix, a suture of prepared horse-hair may be passed through each labial and lin- gual corner and tied between the teeth. The sutures should be removed on the third or fourth day. The after-treatment should consist of frequent irrigations of the mouth with antiseptic solutions and careful removal of food debris from around the seat of the operation, and such other means as will secure the most perfect hygienic condition of the mouth. Prognosis. — ImiDlanted teeth, like transplanted teeth, sooner or later are lost by resorption of their roots. Many cases of implanted teeth, how- ever, never formed any kind of union as the result of suppuration which immediately followed the operation ; others formed a slight attachment to the alveolus and loosened after a few weeks or months, and dropped out or were removed with the fingers ; still others became firmly attached, and remained firm for a year or two, when they became loose from resorption of their roots, and on account of intense irritation had to be extracted ; while a very limited number have done good service for periods ranging from three to ten years. On the whole, then, the operation is not one to be recommended except under the most favorable circumstances, — viz., when a freshly extracted healthy tooth can be inserted into the newly formed alveolus of a youth or young adult of the most perfect health and constitution. CHAPTER XXXII. DISLOCATION OF THE TEETH. Definition. — Dislocation, from the Latin dislocatus, to put out of place ; luxation, from the Latin luxatus, to put out of joint. A dislocation or luxation is a displacement of a part from its normal situation. Two or more bones whose articular surfaces have lost, wholly or in part, their natural relationship are said to be dislocated or luxated, and the condition would be termed a dislocation or luxation. A tooth which is partially or completely dislodged from its alveolus is said to be dislocated or luxated. Dislocations of the teeth are of two classes, — viz., partial and complete. A partial dislocation is one in which the tooth is loosened and i^artially dislodged from its normal attachments and position. A complete dislocation is one in which the tooth is .completely or wholly dislodged from its normal attachment and position. Dislocations of the teeth are always the result of some form of external violence, such as direct blows or falls upon the teeth, accidental dislodge- ment of a contiguous tooth in the operation of extraction, or violence ap- I)lied indirectly, as a blow or fall upon the chin or the side of the face. Injuries which cause fractures of the jaws almost invariably produce dis- location of one or more teeth at the line of the fracture. In partial dislocations the tooth may be either dislodged in an outward direction or driven into the alveolus to a greater or less extent, while in comijlete dislocations the tooth may be entirely dislodged outwardly, or completely driven through the alveolus into the nose or the antrum of High- more. Treatment. — In the treatment of partial outward dislocations of the teeth the parts should be thoroughly irrigated with antiseptic solutions, cleansed from all blood-clots and foreign substances or loose pieces of frac- tured alveolar process, the teeth forced back into their normal position and supported by ligatures of silk or wire, or firmly held in place with a vulcanite or metal splint cemented to the adjoining teeth, and allowed to remain until union with the alveolar tissues has taken place. This result may be confidently expected in from one week to ten days, provided sup- puration does not supervene. To guard against the establishment of suppuration the mouth and the injured parts should be frequently irrigated with antiseptic solutions. In the treatment of those cases in which the tooth is partially driven through the alveolus, the crown of the tooth should be grasped by a pair of suitable forceps and drawn down to its normal position. In a majority of these cases, however, it will be found that the attachment of the tooth to the alveolar wails has been entirely broken up, so that when force is applied to draw the tooth into position it will be completely dislocated. 501 602 OPEKATIVE DENTISTRY. If the tootli still retains a partial attacliment to tlie alveolus, it should be treated as just described, and held in position by means of a ligature or a splint. As a rule, teeth which have been dislocated even partially have suffered rupture of the nerve and blood-vessels at the apical foramen, so that in a short time, ranging from ten days to a few weeks, the tooth gives evidences of containing a devitalized pulp, and should therefore be opened, the pulp extirj^ated, and the pulp-canal filled. Occasionally, however, if the tooth is immediately replaced in its normal position, union of the blood-vessels and the nerve may take place. I^umerous cases of this character have been reported from time to time in dental text-books and periodical literature. The writer has had two such cases in his own practice, — one a lower second bicuspid, which responded to the usual tests of heat, cold, and the electric current twelve years after- wards, and the other a second lower molar, which was vital two years afterwards. These cases were both of them in young women of vigorous health and good family history. These results are more likely to follow such accidents occurring in the young, particularly if they happen during the formative period of the teeth, than if they occur at any time there- after. In tubercular and syphilitic individuals replantation of dislocated teeth is rarely successful, as injuries of even a trivial nature are prone to inflammation and suppuration. Teeth which have been completely dislocated outwardly should, before being replanted, have the pulp extirpated and the pulp-canal filled with gutta-percha, and the apical foramen and the crown-cavity filled with gold. These operations should be performed under the strictest antiseptic pre- cautions, as suggested in the section of the chapter on Dento- Alveolar Abscess devoted to replantation of the teeth. Injuries which cause dislocations by driving the teeth into or through their alveoli and into the nasal cavity or the antrum of Highmore usually cause more or less severe fracture and comminution of the alveolar process and superior maxillary bones. Such injuries are generally the result of falls from a considerable height, as from a building, or being thrown from a horse or a bicycle, or from some crushing injury like railway accidents, the overturning of a carriage upon the occuiDant, or an elevator accident whereby the head is caught between the moving car and the floor. But even under such circumstances it is possible in many cases to bring the fractured bones into normal apposition and to successfully replant the teeth. ^ It is surprising how readily reunion will take place in these cases, and what good cosmetic results may be obtained by the aj^plication of a little skill and patient, intelligent, after-treatment. The first thing to be done in these cases after the mouth has been cleansed of blood- clots and rendered as nearly aseptic as the circumstances will permit, by the liberal use of antiseptic solutions, is to search for and remove all of those teeth which have been driven into their alveoli or into the nasal cavity or the maxillary sinus. In nearly all of these cases it will * Marshall's Injuries and Surgical Diseases of the Face, Mouth, and Jaws, 1897. DISLOCATION OF THE TEETH, 503 be found that the alveolar process is split open, the external plate of. the process being the one which is usually fractured and forced outward. This condition very materially assists in the effort to find and remove the buried teeth. The teeth so dislocated are often completely buried out of sight, or are lost in the antrum. Diligent search must be made for all missins: teeth : Fig. 583. and if one has been driven into the antrum, this sinus Torsion forceps. must be opened by enlarging the alveolus of the tooth, and the tooth removed. This is sometimes a difficult problem ; but if the opening be made sufficiently large, the tooth can be grasped by a pair of torsion forceps (Fig. 583), or bullet forceps (Fig. 584), and removed ; if the forceps will not retain their grasp upon the tooth, it is possible to remove it with a wire-loop snare (Fig. 585) or an ecraseur such as is used for the removal of nasal polypi. After the completely dislocated teeth have been extracted, all loose fragments of bone should be re- FiG. 584. moved from between the alveolar plates and the bones brought into correct apposition. In order to retain them in their normal position it may be necessary to pass silver sutures through the alveolar plates by first drilling holes for their reception at suitable locations. Lead buttons may be used at the termini of the sutures to keep them from cutting into the soft tissues. After the fractured bones have been adjusted the alveoli should be cleansed from blood- clots, and the teeth, which had been previously cleansed and placed in a tepid three per cent, solution of carbolic acid or a Fig. 585. Bullet forceps. Qooeh's double canula snare. 1 to 1000 bichloride solution, may now be replanted in their normal position and retained by means of ligatures. The first part of the operation would of necessity be of such a painful nature that a general anaesthetic would be required, and the length of time that would be necessary to remove the pulps from the teeth and properly fill them would make it impossible to do this while the patient was under the anaesthetic. While, upon the other hand, the chances of reunion of 504 OPERATIVE DENTISTRY. the replanted teeth with their alveoli is much greater if the teeth are replaced within an hour or two after the injury which has dislocated them. The pulp -canals of such teeth may be opened later, and such treatment instituted as the conditions indicate. ''It is interesting in this connection to note the time required to produce death in the various tissues of the body by the arrestation of the blood-current. The period varies in the different tissues. Brain-tissue, renal epithelium, and intestinal epithelium die in two hours. Skin, bone, and connective tissue continue to live over twelve hours." (Cohnheim.) Tissues which exercise special functions die more quickly than those which do not exercise such functions. These facts should govern all operations for the transplantation or replantation of teeth. Success is more likely to follow the effort of transplanting and replanting of teeth if the operation is completed within an hour or two after the extraction of the tooth.* Sometimes a single anterior tooth will be driven through its alveolus and into the cancellated tissues beyond, penetrating the floor of the nasal cavity, without fracturing the alveolar process. Under such circumstances the tooth will be so firmly fixed as to require considerable force to dis- lodge it. The writer saw a case of this character at one time in which a central incisor was driven completely out of sight, and the tooth was sup- posed by the patient to have been knocked out and lost. The case was so diagnosed, also, by the family physician and the dentist. Careful examina- tion with the probe, however, discovered the crown of the tooth about a third of an inch beyond the border of the alveolus, which was, after con- siderable difficulty, extracted with a pair of very thin-beaked, straight root-forceps. The tooth, after the removal of the pulp and appropriately filling the canal, apical foramen, and crown-cavity, was replanted and made a good union. Prognosis. — The prognosis of replanted teeth under the conditions just mentioned is exceptionally good in all healthy subjects. The period of the future usefulness of such teeth may be confidently expected to ex- tend over many years. In some of them, however, there is, after a vary- ing period, a tendency to resorption of the root, and ultimate loss of the tooth. * Marshall, Injuries and Surgical Diseases of the Face, Mouth, and Jaws, p. 98. CHAPTER XXXIII. FRACTUKES OF THE TEETH. Definition. — Fracture (from the Latin /racfjtra, a break), the breaking of a bone or a tooth, eitlier by external violence or other form of injury. Fractures of the teeth, like fractures of the bones, may be divided into three classes, — ^viz., simple, comjDound, and comminuted. Simple fractures are those which involve the hard structures of the crown and do not injure the puli?. Compound fractui^es are those in which the fracture is of such extent as to involve the j)ulx) in any portion of the crown or root. Comminuted fractures are those in which the tooth is broken, crushed, or si3lit into many fragments. Simple fractures may be of such a nature as to involve only a very small portion of the enamel, or they may be so extensive as to involve a large section of the crown and nearly expose the pulp. The incisors, from their exposed position, are more liable to fractures of all classes than the bicuspids or the molars, while the cuspids, from their peculiar form and great strength, are the least liable to such acci- dents, though they are by no means entirely exempt. The causes which produce simple fractures of the anterior teeth are grinding the teeth and incising such substances as threads, which chip the edges of the enamel, or blows and falls, which cause fractures of larger portions of enamel and dentin, while such fractures occurring in the bicuspids and molars are usually produced by biting hard substances or by blows and falls upon the chin, which drive the jaws together and split off a cusp or produce more serious injury. Slight fractures confined to the enamel need only to be made smooth with files, stones, or disks, and then polished with pumice. When larger sections of the crown are broken away, the lost portions should be restored with gold or porcelain. It must not be forgotten, however, that injuries which expose the dentin often leave this portion of the tooth extremely sensitive, and not infrequently cause hypersemia and death of the pulj) as a result of the shock induced by the injury, or from thermal impressions upon the exposed fibrillfe. The application of escharotics to the exposed dentin for the purpose of obtunding its hyx^ersensitiveness is to be deprecated, for the reason that such applications often cause severe irritation and hypersemia of the piilp, which may result in devitalization. For these reasons it is better to treat such cases by covering the exposed dentin with gutta-percha or zinc oxy- phosphate cement and wait for developments. If after a month or six weeks the tooth remains vital and is not hypersensitive to thermal changes, a permanent restoration of the lost portion with gold or porcelain may be undertaken, 505 508 OPERATIVE DENTISTEY. Compound fractures are generally the result of severe injuries, such as blows or Mis, which bring the anterior teeth in contact with some hard substance, causing fracture of the crown and exposing the pulp, or which drives the jaws forcibly together and splits the crown of a bicuspid or a molar through the pulp-chamber, or carries away a large section of the crown, exposing the pulp. The fragments in fractures which occur through the pulp-chamber, sometimes in such close apposition that the most careful examination is necessary to detect the character of the injury. The writer has seen several cases in which a persistent odontalgia was finally discov- ered to be due to such a cause. Bicuspids and molars which have been filled upon the mesio-disto- morsal surfaces are quite prone to be fractured through the pulp-chamber or to have a cusx3 split off while chewing very hard food, or when acci- dentally biting upon some foreign substance hidden in the food, like a piece of bone, a shot, a piece of shell or stone. Compound fractures of the anterior teeth are usually either transverse or oblique, while in the bicuspids and molars the line of fracture is gen- erally oblique or longitudinal, following the line of the pulp-chamber. Oblique fractures are, however, the most common in both the bicuspids and molars. In bicuspids which have two roots, and in the lower molars, the fracture in the crown may extend in a longitudinal direction, separa- ting the roots, while in the superior molars it usually separates the palatine from the buccal roots. Occasionally the root of an anterior tooth may be fractured transversely at some distance beneath the gum. Treatment. — Fractures, either oblique or transverse, which open the pulp-chamber, but do not extend beneath the gum, should be treated with a view to finally setting an artificial crown upon the remaining firm root, but in those cases in which the fracture follows the pulp-canal, or in which the root is otherwise seriously involved, extraction is the only treatment to be recommended. An exposed pulp should be extirpated at once in order to give relief from the severe pain. This should be done under a general ansesthetic. In devitalized superior molars and in double-rooted superior bicuspids which have been fractured on a line with the pulp -chamber separating the roots it is sometimes possible, after ligating the fragments together with a stout silk ligature, to secure the fractured parts and retain them in a nor- mal position by drilling a hole through the crown bucco-lingually, well towards the gum, counter-sinking the hole upon both the buccal and lin- gual surfaces and inserting a bolt with a screw-nut made of eighteen-carat gold, filling over the head of the bolt and the nut with gold or with zinc oxyphosphate or amalgam, and replacing any fillings in the line of the fracture through the crown with cement or amalgam, and in very rare instances with gold. Another method is to fit a gold or platinum band to the outer circum- ference of the tooth, and retain it in position with zinc oxyphosphate. This method is particularly applicable to the lower molars which have been so fractured as to separate the mesial and distal roots. Still another method may sometimes be adopted with success in those FRACTURES OF THE TEETH. 607 cases in whicli the crown is considerably decayed or contains large fillings, — viz., to set a gold shell -crown. This may be accomplished by first se- curing the fragments in proper apposition by the aid of a piece of fine iron binding wire passed around the cervix of the tooth and twisted tightly. The crown may then be cut to proper shape and length, measured, the band fitted, and the crown made and finished by the usual methods. Comminuted fractures are always the result of severe injury from con- cussion or some heavy crushing force, which usually so comminutes the crown and root, together with the alveolar walls, as to destroy the integ- rity of the tooth and make it necessary to remove the crushed fragments. Occasionally the crown only will be comminuted and the root left intact. Under such circumstances the root may be conserved and an artificial crown set upon it. Spontaneous fracture sometimes occurs in a tooth which contains a de- vitalized pulp or a very large metal filling without any seemingly apparent cause. It has been suggested by some writers that in the former the tooth was fractured by internal pressure from the evolution of gas in a closed pulp-cavity as the result of the decomposition of the pulp ; while in the latter it was due to the expansion of the metal filling induced by thermal changes. Tomes suggests that it may be due sometimes to a calcified pulp, which acts as an internal wedge when a distorting force is brought to bear upon the tooth. It is possible that such forces as have been mentioned may produce these fractures, but the writer is inclined to the opinion that in each of these conditions the fracture is often due to some unusual force applied to the tooth, either in masticating or in grinding the teeth together while the individual is asleep. A tooth with a devitalized pulp has usu- ally been weakened by a cavity of decay, while a tooth which contains a large metal filling is also in a weakened condition, and therefore less able to withstand any undue strain that might be placed upon it. Union of Fractured Teeth. — As a rule, teeth which have been frac- tured do not become reunited. This is no doubt due to the fact that the dentin has no blood circulation, and that the cementum has but few blood- vessels as compared with bone-tissue, and yet there are several instances on record in which union of fractured teeth has undoubtedly taken place. Fractured bones almost universally reunite, and but for the character of the dental tissues the same result might be confidently expected in the teeth. The union which has taken place in the few instances recorded seems to be due to the active agency of the pericementum, which has thrown out new osseous (cement) material around the fracture, just as is done by the periosteum in fractured bones. It is possible that the pulp in some rare instances may take part in forming the reunion. Eeunion of fractured teeth is much more likely to result if the fracture takes place during the formative period of the root, or soon thereafter, than it is if the fracture occurs after adult life is reached. The probability of reunion taking place in a fractured tooth is increasingly greater as the line of fracture nears the apical third of the root. The conditions which are necessary to promote reunion in the fractured root of a tooth are correct apposition and immobility of the fractured 508 OPERATIVE DENTISTRY. parts, the vitality of the pulp, and a healthy condition of the pericemen- tum. Eeunion will fail if the fractured parts are separated by any appre- ciable space, or if they are in constant motion, or the pulp dies and be- comes decomposed, as septic conditions are established at the site of the injury, and by that means the reparative process is arrested or entirely prevented, and if the pericementum is not in a fairly healthy condition the reparative process cannot be established, as this is the most important structure involved in this process. Wedl * is of the opinion that the pulp takes some part in the process of reunion of fractured teeth, and he figures two reunited fragments in which a deposition of reparative dentin took place, — one was a human superior bi- cuspid, the other an incisor of an antelope. Tomes f mentions two cases, one a human molar in which union of the fragments had been secured by the formation of new cement-tissue around the fracture. The other was a tusk of a hii)popotamus in which the fragments had been considerably sepa- rated, but which had been perfectly reunited with new-formed cementum. Professor Owen mentions a similar case in the tusk of a hippopot- amus. X Hyatt describes a specimen of reunited fracture of a central incisor to be found in the Anatomical Museum of Breslau. Heider mentions a specimen contained in his private collection of a perfectly reunited fracture in a superior bicusiDid. Hohl records fourteen cases found in man and the lower animals, eight of which were human, seven being incisors and one a superior bicuspid. One remarkable case recorded by Hohl in which reunion was perfect is described as follows : '' Professor Y., as he was about entering a railway car, fell, striking his mouth upon the sharp edge of an iron step in such a way that the right superior central incisor was fractured lengthwise. The fracture separated the tooth in the middle of the crown so completely that the two fragments diverged from each other, and could be moved back and forth. After the lapse of fourteen days, during which time the intense pain entirely pre- vented the use of the fractured tooth, a more comfortable condition en- sued, and in a few weeks more the tooth completely resumed its normal functions. The two halves of the tooth became firmly adherent to one another, and the line of union was indicated by merely a fine line with a slightly brownish tinge." § The late Sir E. Saunders has described an incisor belonging to his private collection, which shows a perfectly reunited fracture which had occurred at the junction of the middle and apical thirds of the root. Belisario also reports a case of fracture of a tooth with reunion of the severed fragments. Bennett describes a fractured incisor tooth in which the fragments were apparently considerably displaced and had become reunited in their displaced position. * Wedl's Dental Pathology. f Tomes' s Dental Surgery. t Odontography. § American System of Dentistry. CHAPTER XXXIY. RESORPTION OF THE ROOTS OF PERMANENT TEETH. Definition. — Resorption (Latin, resorptio, from re, again, and sohere, to absorb), the process wliereby formed tissue is converted into its original elements by the action of specialized cells and taken into the blood-cur- rent by absorption. Bone is resorbed through the action of the osteoclast cells. The roots of the permanent teeth are resorbed by a similar process, and is analogous to that observed to take place in the roots of the deciduous teeth prior to their exuviation. The former, however, is a pathologic condition, while the latter is physiologic. The resorption of dental tissues other than that appearing in connec- tion with the removal of the roots of the deciduous teeth prior to the eruption of the permanent teeth must therefore be considered a pathologic process. Causes. — T\iq principal predisposing causes of resorption of the roots of the permanent teeth are of two classes, — one which is dependent upon con- ditions associated with the tooth itself, and the other to conditions which are entirely foreign to the tooth. In the first class of causes are death of the pulj), necrosis of portions of the pericementum, and functional disuse of the tooth due to the loss of its antagonist. In the second class are irritation from an erupting but malposed tooth, as, for instance, a third molar, which presses against the distal root of a second molar, or the presence of a foreign body in con- tact with the root. The process of resorption is much more rapid in pulpless teeth and in those in which portions of the pericementum have been destroyed by a suppurative inflammation, such as would attend dento-alveolar abscess. It may be stated as a general fact that the progress of the disease is much more rapid in tissues whose blood-supply or nutrition have been reduced or largely cut off, while, on the other hand, the greater the blood- supply coming to the part so attacked the more successfully will it resist the de- structive process. In other words, vital resistance plays an important part in determining the rapidity with which the tissues are dissolved by this process. When the process attacks a tooth with a vital pulp, its action is more and more retarded as it approaches the pulp, and in some of these cases the cementum and dentin have been removed, leaving only a thin tube-like pro- tection of dentin surrounding the pulp. In those cases of resorption caused by an advancing malposed tooth, it will be noticed that at the point of con- tact only will the i)rocess be active, and the form of the excavation made in the root of the tooth attacked by the resorptive process will correspond to that portion of the surface of the tooth which is advancing towards it. 509 510 OPERATIVE DENTISTRY. There is never, however, absolute contact of these surfaces ; they are always separated by a mass of multinucleated cells which are doubtless modified osteoclasts. The process of resorption sometimes extends to such depth as to expose the pulp in the root of the tooth, and thus cause a severe and sometimes obscure odontalgia and later on a dento-alveolar abscess. Exciting Causes. — Continued irritation of almost any form may in- augurate the resorptive process. Among the more common of the exciting causes may be mentioned chronic septic pericementitis, chronic dento- alveolar abscess, a nerve broach broken olf in the pulp-canal and project- ing through the apical foramen, the presence of a root-canal filling which projects into the apical space, or a severe injury, as from a blow upon the tooth. In certain cases, however, the resorptive process seems to have no discoverable cause whatever. Pathology. — The macroscopic appearances of the roots of teeth which, are being resorbed present such a wide difference that it may be safely said that the process rarely attacks any two teeth alike. This will be noticed by reference to the illustrations. Fig. 586 shows the result of a chronic irritation at the apex of a vital superior central incisor. In this case tbe resorption has produced a smooth, regular, and rounded shortening of the root. Fig. 587 illustrates the same condition occurring at the apices of roots of a devitalized superior molar. Fig. 588 represents two vital superior central incisors in which the process of absorption was most active upon the mesial surface, extending from apex to cervix. The writer is indebted to Dr. Wright, of Chicago, for these latter specimens loaned from his private collection. The surfaces which have been attacked in these teeth, present deep, uneven, bay-like excavations and numerous small, rounded open- ings, which give them the appearance of being worm-eaten. In Fig. 589 the process is shown to have scooped a large, smooth excavation in a devitalized superior bicusj)id, well up towards the apex, leaving sharp, clean-cut edges. Sometimes the whole root is absorbed, but this is rare. Fig. 590 shows a devitalized inferior bicusi)id in which the disease has extended much farther. This tooth had been crowned with gold several years before the writer saw the case, and no other history could be ob- tained. In this case the resorptive process had extended into the crown upon one side. Fig. 591, a devitalized central incisor, has lost about one- half of its root ; the disease evidently began on the labial aspect of the root near the apex. In this case the dentin has been dissolved much more readily than the cementum, thus causing a very deep depression. Fig. 592 shows a devitalized superior central incisor in which the process of resorption has gone considerably farther, and has removed almost the entire root and formed a deep dei^ression in the crown. Fig. 593 was a vital superior cuspid which, has a small depression or cup-shaped cavity upon the labial surface of the root near the middle, and shows a very early stage in the resorptive process. Fig. 594 was another vital superior cuspid in which the disease began at tlie apex and has destroyed the upper half of the root. The peculiarity of this case lies in the fact that the disease has hollowed out the root Fig. 586. Fig. .587. Fig. 588. Fig. 589. Fig. 591. Fig. 592. □ Fig. 596. Fig. 593. Fig. 594. Fig. 595. Fig. 597. — Osteoclasts, producing resorption of the root of a tooth. X 45. Tig. 598. — Osteoclasts, producing resorption of the root of a tooth. RESORPTION OF THE ROOTS OF PERMANENT TEETH. 511 almost to tlie cervix, leaving the outer shell of the cementiim intact, and preserving a thin tube of dentin around the pulp. Fig. 595 represents the most interesting case of all. This is a lower sec- ond molar, which had been extracted and replanted by a colleague for the cure of pyorrhoea alveolaris. The tooth was supported in position by a gold splint which encircled this tooth, the first molar, and the second bicuspid. The operation was made about two years previously. The tooth had been troublesome for more than a year, but, as there was no discharge of pus, it was thought best to allow it to remain. It finally caused irritation of the gum, and was therefore extracted. In this case the root and a large part of the dentin of the crown was entirely resorbed. The tissue, how- ever, was not removed in the same manner as in the resorption of the deciduous teeth, for in them the surface is left comparatively smooth, while in this case it is full of deep depressions and perforated with holes, as though worm-eaten. Fig. 596 shows a very peculiar form of resorption in a superior second molar, the result of inflammation of the pericementum induced by drilling through the side of the root in an effort to open the pulp- canal in the disto- buccal root. The probes are passed through the cavity of decay and the Oldening in the root made by the drill and through two other openings which were the result of the action of the cementoclasts. Upon microscopic examination of the surface which is being resorbed it is found to be covered with cu]3-shaped depressions of great minuteness, but there ai^pears to be no alteration in the size or of the arrangement of the dentinal tubuli. These minute depressions are Howship's lacunse, and are doubtless formed by the action of multinucleated cells (Figs. 597 and 598), the osteoclasts, or odontoclasts. The modus operandi by which the roots of the permanent teeth are re- sorbed seems to be identical with the process by which foreign substances composed of animal tissue, like ivory, catgut, silkworm gut, silk-ligatures, sponge, and decalcified chicken-bone drainage-tubes, etc., are resorbed when buried in the living animal tissues. The success of the process seems to depend upon the character of the inflammation, which must be of a degree that falls short of the suxjpurative j)rocess. This fact has been conclusively proved by numerous experiments (Billroth, Tomes, Krause, Kollicker, and others) with buried ligatures and other animal tissues. It was found that the establishment of the suppurative process immediately arrested resorption. This is doubtless due to the fact that the increase in the degree of the inflammatory i)rocess arrests the function of the resorp- tion cells or odontoclasts. Similar conditions are known to obtain in the exuviation of the de- ciduous teeth. Resorption in these teeth never progresses while suppura- tion exists about their roots. This is doubtless true also of the resorptive process in the roots of the permanent teeth. The examination of the roots of rexDlanted, transplanted, and imj^lanted teeth reveals the fact that where union or attachment has taken place with- out suppuration, and the teeth were subsequently extracted during some j)eriod soon after the ox)eration, resorption must have taken i)lace in various 512 OPERATIVE DENTISTRY. locations, for excavations into the cementum are plainly seen, and these have been refilled by a deposition of new-formed cement tissue. Occasion- ally the alveolar tissues never become tolerant of these teeth, particularly the transplanted and the implanted ones, and under such circumstances the resorptive process is established and maintained uninterruptedly until the offending members, which act as foreign bodies, are expelled from the jaws. Symptoms and Diagnosis. — The symptoms are tenderness to per- cussion, a peculiar looseness of the tooth, which can be moved in a radius shorter than would be expected in a tooth of normal length ; later evidences of a mild pericementitis appear, and sometimes a slight discoloration of the tooth. On opening the pulp-canal the pulp is usually found to be de- vitalized, and upon passing a broach into the canal it encounters midway, or in the upper third of the root, a soft, fleshy mass of tissue. At other times the tooth may contain a vital pulp, and if it has been exposed by entering the canal with a drill, it must be devitalized ; but upon its re- moval and the exploration of the pulp-cavity the tooth will be found to have either undergone shortening of its root, or the probe will reveal the fact that the wall of the pulp-chamber has been invaded, and the cavity so made occupied with a mass of soft tissue. In vital teeth which are being thus resorbed the pulp will sometimes give evidence of being hypersemic by the marked increase in the normal heat sense of the tooth, and its intolerance to changes of even a few degrees in the temperature of substances coming in contact with it. In some of these cases the only symptom is one of discomfort, — not actual pain, but a discomfort which the patient will, perhaps, suggest does not seem likely to be relieved except by the extraction of the tooth. The diagnosis in the absence of positive signs may be made by exclusion. The Eontgen rays, however, if available, will give a positive diagnosis. Prognosis. — The prognosis, so far as the conservation of the tooth is concerned, is decidedly unfavorable. When once this process is established in a permanent tooth, it is sooner or later lost. If the diagnosis in these cases could be made early, and the source of irritation removed before the process of resorption had progressed to any considerable extent, it is possi- ble that the process might not only be arrested, but that a redeposition of tissue would take place and the tooth be preserved. But the difficulty lies in the fact that there seems to be no means of diagnosing the disease until it has gone so far as to make it impossible to save the tooth. Treatment. — Inasmuch as the only symptoms which are manifest in these cases are those of a mild pericementitis, every effort should be made to discover and remove, if possible, the cause or causes of irritation. If the tooth is one that has been devitalized or gives evidence of containing a dead pulp, the pulp-cavity should be opened and cleansed ; or the filling removed if one is found ; or broken instruments lodged in the pulp-chamber should be searched for and, if discovered, removed. But if, after treating the case antiseptically for a few days longer, there is no improvement in the conditions or abatement of the symptoms, the tooth should be extracted as the only means of giving relief. CHAPTBE XXXY. HYPERCEMENTOSIS. Definition. — The term hypercementosis (from the Latin ccementum, coarse stones, and hyper, the prefix used to denote superabundance) means an abnormal excess in growth — hypertrophy — of the cement-tissue of the tooth. Hypertrophy is an increase in the substance of a tissue or an organ, the result of an increase in or the multiplication of its elements, and brought about in such a manner that the structure of the hypertrophied tissue is not materially changed and does not differ essentially from the normal type. Hypercementosis is therefore a simple increase in the volume of the elements which constitute the cement- tissue of the tooth, which retains in large measure the general character of the structure of the normal tissue. It may be circumscribed or diffuse, and may assume almost any size or shape. Causes. — The etiologic factors which produce this affection are of two classes, predisposing and exciting. The predisposing causes of hypercementosis are generally the result of those conditions, either constitutional or local, which induce a morbid activity in the cellular elements of the peridental membrane, especially those which increase its blood-supply beyond the normal. This condition may be produced by chronic inflammatory phenomena resulting from septic conditions of the pulp-canals of devitalized teeth or other cause of a low form of inflammation ; by malocclusion, or overuse of the tooth, causing congestion ; by the death of the pulp, which increases the blood- supply to the pericementum by diverting to it that portion of blood which originally supplied the pulp ; by the selective action of such drugs as mercury, iodine, etc. , which produce pericemental irritation and gingivitis ; by the irritation of mephitic gases contained in the tubuli of devitalized teeth percolating through the cementum and inducing chronic pericementitis, a condition which frequently occurs in teeth whose pulps have been removed and the canals properly filled ; while the presence of an excess of uric acid in the blood maj' also be classed as a predisposing cause, as it favors the deposition of the urates in the pericementum and thereby produces chronic irritation, which causes congestion of this membrane and, under favorable conditions, organization of the inflammatory exudates. The tendency of the pericementum to develop such excess of cement- tissue is undoubtedly in some instances constitutional, and is especially marked in certain individuals. This tendency seems in some eases to be inherited, and it is fairly good presumptive evidence that if the parents have developed the affection, the children will also suffer from it. Exciting Causes. — The exciting or active causes of the affection may be any form of irritation which excites a hypersemic condition of the pericementum, such as excessive thermal changes, a severe strain upon the 33 513 514 OPERATIVE DENTISTRY. tooth, as in using great force to crush or incise a hard or tough substance, or the accidental biting upon some hard substance like a piece of bone, a shot, or a piece of stone ; or an injury from a blow or fall ; caries of the cervix ; the projecting edge of a filling ; the protrusion beyond the apical foramen of a gutta-percha or other filling-material, and cervical deposits of salivary calculus. Pathology. — Inasmuch as the formation of cementum is normally a more or less continuous process, beginning with the development of the root and the eruption of the tooth and ending only with its loss or the death of the individual, it becomes very difficult to draw the line at the point where cement formation ceases to be physiologic and assumes patho- logic features. An examination of a recently erupted tooth, one with its root developed to the normal length, shows the cementum to be composed of only a few concentric layers, while a tooth from an elderly person shows many such lamellse. But although the cementum is thin at the cervix and thick at the apex, the number of lamellse are about the same in all parts of the tissue. The formation of the cementum in lamellse indicates periods of functional activity and of rest upon the part of the cementoblasts (Figs. 599 and 600). These lamellse closely follow the general outine of the dentin composing the root and form an even and smooth outer surface. In many pathologic specimens the surface presents a nodular appearance, or larger globular masses are formed at the apex or upon the side of the root, as seen in B and C, Fig. 601. In others, like the bicuspids and molars, the roots may be united, sometimes by simple fusion as shown at A, Fig. 601, at others by a considerable mass ; or the roots of two or more teeth may be joined together, as shown in D, Fig. 602. Fig. 602, which is made from a specimen kindly loaned the writer by Dr. Wright, of Chicago, shows a similar condition. Specimens of hypercementosis often show very great irregularity in the lamellation and in the surface of the dentin. At certain points deep excavations appear in the surface of the dentin, while other similarly ap- pearing excavations are filled with cement tissue which has no regular lamellated structure. Extensive areas of absorption upon one part of the root and large additions of new tissue upon another part may be observed in the same specimen. The character of the irritation which has stimulated the activity of the formative function of the cementoblasts is indicated by the surface of the new-formed cementum ; the smoother and more regularly globular its form (Fig. 603), the more continuously chronic has been the i^rocess, while if the surface is irregular or composed of numerous elevations and depressions, it is an evidence of irregularity in the character of the irri- tation, and indicates intermittent attacks of resorption and deposition. When such teeth are extracted the pericementum is found to be much thickened and abnormally vascular. Sometimes there will be found adherent to the irregular surface of the new-formed cementum certain flesh-like masses which remind one of the absorbent organ found attached to exuviating deciduous teeth. Examined microscopically, the new-formed cementum is shown to i' " '1 I 4 * v-* Dentin / V Cementum Fig. 599. — Transverse section of root of human tooth near the apex, showing dentin and cementum in hypercementosis. X 200. Cementum Lamellae Canaliculi Pig. 600. — Transverse- section of root of human tooth near the apex, showing the dentin and the ce- mentum. X 175. Fig. 601. B C M^^K ^ ^^H .^^^K^ Fig. 602. Fig. 603. Fig. 604.— Transverse section of root of human molar, hypercementosis. X 96. Fig. 605.— Vertical section of root of human molar, hypercementosis. X 15. Dentin Fig. 606. — Transverse section of roots of human molar, near apex. X 75. Fig. 607. — Transverse section of root of human tooth, hypercementosed, showing the irregular character of the new-formed tissue. X 75. Fig. 608. — Transverse section of alveolus and apex of root of abscessed human molar, showing resorption area partially refUled with a secondary formation of cementum. X 96. Enamel pearl Fig. 609. — Case of inostosis, with formation of a pearl-like globule resembling enamel. Fig. 610. — Transverse section of root of human tooth, showing ease of inostosis. X 80. HYPERCEMENTOSIS. 515 possess the characteristic general structure of cementum, but differing in the size, number, and arrangement of the lacunsB and canaliculi, the thick- ness of the lamellse, and the distinctness of the incremental lines of Salter (Fig. 604). These differences depend in large measure upon the extent or thickness of the new- formed tissue. In normal cementum the thin laminae at the cervix of the tooth present no lacunae, but as the apex is approached they become more and more abundant, as do also the canal- iculi. Similar variations occur in the hypertrophied cement tissue (Fig. 605). Vascular or medullary canals (Haversian canals) are exceptional in normal cementum, but they are frequently found in hypercementosis. The presence of these canals in the cementum is not, however, necessarily an evidence of pathologic conditions, for they are occasionally found in very thick cementum of normal teeth, particularly where two roots are joined together by cement tissue, as shown in Fig. 606. In hypercementosis having a smooth and regular surface the lamellae are fairly regular and the incremental lines of Salter generally well marked. The lacunae are more numerous and slightly larger" than in normal cementum, but irregularly arranged and with the canaliculi running in a peripheral direction, as seen in normal tissue. When the surface of the new tissue is irregular the character of the structure is more or less irregular. The lamellae are not so distinctly marked and the lacunae have a more irregular arrangement. These con- ditions are strikingly shown in Fig. 607. The density and texture of the various lamellae often differ considerably ; some seemingly are very perfectly calcified, with few or no lacunae, while in others calcification is quite imperfect and the lacunae are very numerous. In some cases lamination is not traceable in the new-formed tissue, which fact would indicate that the functional activity of the cementoblasts had been continuous, that there had been no periods of rest, no abatement in the stimulation or irritation. INOSTOSIS. A most curious condition is sometimes noticed in the structural arrange- ment of the new cement tissue, a condition which unmistakably indicates that lamellae already formed had been partially removed by resorption, and the excavations thus made afterwards filled by a redeposition of cement- tissue, as shown in Fig, 608. The process by which cement-tissue is re- formed in the excavations made by resorption has been termed by Henry inostosis. The new-formed tissue in inostosis is sometimes of very peculiar character. Occasionally it resembles osteodentin, at other times it has the appearance of enamel. Fig. 609 is a case from the private collection of the writer which shows a pearl-like body in the side of the root of a third lower molar, occupying a cavity apparently formed by resorption. Fig. 610 is a microscopic section of a similar case from the private collection of Dr. Y. A. Latham, but lying deeper in the dentin. These phenomena represent two distinct vital processes, processes which are antagonistic to each other. One is formative, the other de- 516 OPERATIVE DENTISTRY. structive. The explanation would seem to lie in the character and degree of the irritation, operating at different i)eriods or in different locations at the same period. It has already been noticed that a mild and continuous chronic irri- tation of the peridental membrane favors the production of new cement- tissue through stimulation of the cementoblasts, while it is a recognized fact that another form of irritation, which is perhaps only a little more severe, will establish a retrograde or destructive process in the tissues, as noted in the resorption of bone by the stimulation of the osteoclasts. A similar condition doubtless takes place in the resorption of the cementum, for there are often found attached to such teeth masses of tissue composed of giant-cells which cannot be distinguished from the multinucleated cells found in the " absorbent organ" attached to exuviating deciduous teeth. It has never been definitely determined whether there are two distinct sets of cells — cementoblasts and cementoclasts — or whether the cementoblasts under different stimuli do not perform both functions of formation and of resorption. Specimens are occasionally exhibited in which well-marked resorption was present upon one side and hypercementosis upon the other, which would indicate that these processes were the result of localized irritations of different degrees. Although this excessive growth of the cementum may result in the fusion of the roots of a tooth, or of the roots of contiguous teeth, or of the crown of one tooth with the roots of another, as shown in Dr. Wright's specimen (Fig. 602), no authentic evidence, to the knowledge of the writer, has so far been i^resented of fusion of the cementum with the alveolar pro- cess. Bones often become auchylosed by fusion of their surfaces, the result of the healing xjrocess, as, for instance, in the temporo-maxillary articula- tion following traumatisms or inflammation of the joint. Sometimes the new-formed tissue in hypercementosis seems to establish a union with the alveolus, and when the tooth is extracted it not infrequently causes one of the plates of the alveolar process to be' fractured and brought away adherent to the root ; but upon a closer examination it is found that the bone can be detached from the hypertrophied cement tissue after more or les3 effort, as the tissues remain separated by a modified i)ericemental membrane, the fibres of which seem to be very strong and firmly attached to both tissues. Symptoms and Diagnosis. — The local symptoms of hypercementosis are usually negative, and unless the affection causes pain in the tooth or its surroundings its presence may never be suspected. Occasionally, however, the patient may complain of symptoms which would indicate pericemental irritation, — viz., slight soreness and elonga- tion, tenderness to percussion, and pain in the region of the tooth. Some- times tumefaction of the alveolar process over the root may be observable and this may be slightly tender to pressure, but, as a rule, no such positive diagnostic signs are presented. When j)ain is present, it is usually of the reflex, neuralgic order, and generally referred to some remote portion of the face or head or to the eyes or the ears. Numerous cases have been placed on record from time to HYPERCEMENTOSIS. 517 time, in tlie periodical dental and medical literature, of persistent neural- gias in these locations and of functional disorders of the eyes and ears, which have been traced to the presence of hypercementosis of the teeth, and the diagnosis has been proved by the cure of these affections following the extraction of the teeth. Serious derangement of the general nervous system may also result from this form of irritation. Tomes* mentions ^'two cases in which epilepsy appeared to be dependent upon diseased teeth, the most prominent feature being hypercementosis of the roots." Chorea has also been traced to the irritation of diseased teeth, particu- larly to pulp irritation and hypercementosis. These nervous diseases are common in institutions for feeble-minded children, and it was the experi- ence of the writer when serving upon the staff of one of these institutions that many times dental irritation was the cause of these affections, as was proved by the abatement of the symptoms after the extraction of the offending teeth. The diagnosis of hypercementosis is often a problem which presents the greatest difficulties, and in many cases it can only be reached by a process of exclusion. Pain or other symptoms of uneasiness which are not refer- able to any other cause may be the only symptoms present. The patient sometimes says the tooth feels enlarged or swollen and sensitive to percus- sion, but these again may be the only symptoms to guide in the diagnosis. Many persons are subjects of hypercementosis, sometimes to a consid- erable extent, without ever having suffered the least inconvenience there- from, this condition of the teeth not being recognized until, for some other reason, the teeth have been extracted. The best and most reliable means of diagnosing hypercementosis is by means of the Eontgen rays. The picture thus obtained, if made by an experienced operator, brings out the outlines of the teeth and the position and size of their roots in such a clearly defined manner that the diagnosis of hypercementosis, if it existed, could not help but be correctly made. It is not necessary for the dental surgeon to go to the expense of buying apparatus for this purpose, for all large cities, and nearly all first-class hos- pitals, have such facilities for diagnosis and expert attendants ready to photograph any part of the body that may be desired, and thus relieve the dental adviser of all anxiety as to obtaining a good picture, or of the fear of accidents which sometimes come as a result of oft-repeated or long exposure to the effects of the Crookes tube. Treatment. — The only treatment to be recommended for hypercemen- tosis is the immediate extraction of the diseased tooth as soon as the diag- nosis is assured. Immediate relief is not always obtained, but usually, even in the severest forms of iic douloureux dependent upon this cause, the pain will abate after a few days. Functional affections of the eyes and ears which have hypercementosis as their cause, rapidly improve after the extraction of the tooth. In the general nervous affections dependent upon the same cause equally favorable results follow. * Dental Surgery, 4th edition, p. 471. CHAPTEE XXXVI. NECROSIS OF THE TEETH, Definition. — The term necrosis (Greek, vexpoq^ dead) is generally used in its broadest sense to indicate death in any form, whether death of indi- vidual cells, aggregations of cells, or masses of complex tissues. In its more restricted sense it is used to indicate death of tissue en masse, while the term necrobiosis is used to indicate death of cells. In surgery the term necrosis is still farther restricted, and is generally applied to death en masse of bone and like hard structures, while the term gangrene is applied to death en masse of soft tissues. The term necrosis would therefore, when applied to the teeth, indicate death en masse of these organs. The teeth receive their blood-supply and nutrition from two sources, — viz., from the pulp and from the j)eridental membrane. The character of the teeth is such that the vitality of the pulp of a diseased tooth may be destroyed and the tooth still retained in the jaw for an indefinite period, through its organic connection with the alveolus, by means of the cemen- tum and the pericementum. If, however, the vitality of the jjericemen- tum is destroyed, the tooth has no further vital connection with the alveo- lus, for under such circumstances the same cause which destroyed the peri- cementum will also destroy the pulp, when the tooth may be termed necrosed, and it is exfoliated as a foreign body. Nature is always intol- erant of any useless or dead member and immediately sets in operation certain forces to rid itself of the incubus. The expulsion or exfoliation of a necrosed tooth is attended with more or less local inflammation and suppuration of the surrounding parts, the integrity of which will depend upon the cause of the necrosis and the condition of the surrounding tissues. When death of the pulp occurs a partial necrosis of the dentin follows, but this from the clinic stand-point does not mean the loss of the tooth, for such teeth, if jjroperly treated by extirj^ating the devitalized pulj) and fill- ing the canals, may remain without untoward symptoms as useful members of the dental arch for many years, though they are not as valuable nor generally so long preserved as teeth with vital pulps. The probabilities are that the dentin may still receive under such circumstances a certain amount of nutrition through the cementum and the granular layer of Pnr- kinje. This, however, is not endorsed by some authorities. A tooth which has lost the vitality of its pulp is, therefore, strictly speaking, in a state of partial necrosis. Some authorities have maintained that in cer- tain debilitated conditions of the pericementum the devitalization of the pulp would prove helpful in establishing more normal conditions in it by diverting the blood, which was originally intended to supply the pulp, to the vessels of the pericementum. It is somewhat doubtful whether the vessels of the pericementum could carry the extra supply of blood without 518 NECROSIS OF THE TEETH. 519 producing an abnormal hypersemia, and thus defeat the very object that the operation was intended to secure. Necrosis of the cementum is due to the destruction of the pericementum, as this membrane is its principal means of nutrition during the vitality of the tooth and its only means after the devitalization of the pulp. J^ecrosis of the cementum may be partial or complete. Partial necrosis of the cemen- tum is common, but complete necrosis is rare. Causes. — The causes of necrosis may be divided into systemic, or general, and local ; predisposing and exciting. The general predisposing causes are all those conditions which in any way produce debility or disease of the pericementum, while the exciting systemic causes may be such diseases as syphilis, scurvy, mercurialism, iodism, etc. The predisposing local causes are malocclusions, loss of occlusion, local inflammatory conditions of the gums and alveolar process, and death of the pulp. The local exciting causes may be mechanic irritants, like cervical salivary deposits or a rubber band which has been placed upon the crown of the tooth and has been lost beneath the gum ; the pressure from an ill-fitting crown, clasp, or plate ; root fillings which have passed the apical canal and impinge upon the apical tissues ; chemic irritants like arsenic, chromic acid, and caustic potash ; septic conditions arising from a devitalized jjulp or from unhygienic conditions of the mouth ; phagedenic and gouty peri- cementitis, and severe traumatisms like blows and falls or the too rapid movement of the teeth in regulating. Partial necrosis of the cementum may vary in extent from a very small area at the apex of a single-rooted tooth to an entire root of a double- or treble-rooted tooth. The cementum is rarely necrosed in teeth having vital pulps, as is evidenced by the fact that in the recession of the peri- cementum, gum, and alveolus, which sometimes occurs from diseases affect- ing these tissues, the cementum usually maintains its sensitiveness and responds vigorously to all forms of irritation whenever the influences of these agents are brought to bear upon it. ISTecrosis of the cementum, either in part or in whole, is therefore dependent upon death of the pulp and upon partial or complete destruction of the peridental membrane. The most common form of partial necrosis is that which occurs at the apex of the root following alveolar abscess. In these cases the apex of the root is denuded of its pericementum by the septic inflammation which has been present in the apical space and the denuded portions bathed in pus for a considerable period. This necrosed tissue, however, when not too extensive, may, if the septic con- ditions are removed, be resorbed, and later a redeposition of Cement tissue take place as described in the chapter on "Resorption of the Teeth." Another but less common form of partial necrosis of the cementum is that in which an entire root of a multirooted tooth, most often the lingual root of the superior molars, may be entirely divested from the cervix to ihe apex of its pericemental membrane, alveolar process, and gum, or the gum and alveolar process may remain intact. 520 OPERATIVE DENTISTRY. Such conditions usually occur in pulpless teeth, but occasionally the pulp in the exposed root only will be dead, while in the others it may still be vital and the tooth firmly held in place by the attachment of the buccal roots. If under such circumstances the tooth is opened, the living portions of the pulp devitalized and extirpated, and the root- canals filled, the lingual root may be amputated with engine burs or disks and the balance of the tooth allowed to remain. Teeth treated in this manner have been known to do good service for several years. Conijjlete necrosis of the cementum may be caused by acute or chronic inflammatory conditions of the pericementum which may be dependent upon general or local conditions. When complete necrosis of the cementum has occurred as the result of an acute inflammation of the pericementum, the tooth is no longer tolerated by the system, but becomes as a foreign body and is speedily expelled. Under these circumstances the tooth is in a septic condition, and the inflammatory process which is established as a result of septic irri- tation is often very active, causing great pain, suppuration and discharge of pus at the cervix, considerable tenderness and swelling of the gums and surrounding tissues, and looseness of the tooth, which after a few days or weeks is either picked out with the fingers or drops out. When complete necrosis occurs as a result of a chronic inflammation, the process of expulsion is usually very slow, chronic suppuration, loose- ness of the tooth, and periodical soreness being the chief symptoins, and several months or years may be required for its complete exfoliation. Fig. 611 shows a superior central incisor which was completely necrosed and expelled as a result of chronic inflammation induced by drilling through the side of the root and of the protrusion through the opening of a gutta-percha filling. The root is slightly eroded uj)on the labial surface by the action of the odontoclasts, and a thin scale of calcic concretion has formed upon the lingual surface. Fig. 612 is a crowned superior central incisor which had lost its natural crown by a traumatism while the lad was playing ball. The root had been filled with cotton and the crown set with cement. For several years the tooth had been loose, and was finally extracted with the fingers. Extensive resorption had taken place at the apex, exposing the apical end of the cotton filling. Fig. 613 is a transplanted superior central incisor which had been crowned before transplanting. For six years the tooth did well, when suddenly it became very sore and loose, and was expelled after a few weeks. On the distal surface at the cervix is a depression caused by resorption which has penetrated to the pulp-canal, exposing the cement with which it was filled. Fig. 614, a necrosed superior cuspid, was the seat of a chronic abscess for many years ; the tooth finally became so loose that it was extracted with the fingers ; it shows extensive resorption at the apex. In cases of complete necrosis of the cementum the only treatment is extraction. Gutta-percha filling Fig. 611. Fig. Gil. Fig. 61.5. — Epithelial scales and salivary corpuscles from sotdes of the mouth. X 50. CHAPTEE XXXVII. DEPOSITS UPON THE TEETH. GEEEN STAINS. CALCIC DEPOSITS. Green Stains. — The simplest deposits that are found upon the teeth are the green stains so common at the margin of the gums upon the anterior teeth of children and young people and persons of adult age who pay little attention to the cleanliness of their mouths. These deposits are probably formed by the growth of the leptothrix buccalis and certain forms of chromogenic mouth-bacteria which have attached themselves to remains of ]S"asmyth's membrane or a roughened surface of the enamel. Their continued presence causes a softening and disintegration of the polished surface of the enameh which leads to decay. It is, therefore, important that they should be removed early, and if the enamel has become eroded it should be ground smooth with fine Arkansas stones and polished with fine pumice and precipitated chalk. Calcic Deposits. — The calcic deposits which are formed upon the teeth are classed as salivary and serumal, or as '■'■ptyalogenic'^ and ^^ hema- togenic^' (Pierce). The first are formed from the calcic elements of the saliva, the second from the calcic elements of the blood, combined with certain waste or end-products formed from imperfect metabolism. The formation of salivary deposits is usually the result of local causes, but certain general conditions act as predisposing factors. The formation of serumnal deposits is largely the result of constitutional conditions, as, for instance, rheumatism and gout, febrile diseases, and certain kidney affections, like diabetes and albuminuria, which may produce local necro- biosis of the pericementum, terminating in pus formation or in caseous or calcic degeneration of the pus and the formation of adherent concretions. The saliva of the human mouth always contains calcic salts in greater or less quantity. These salts are, under certain conditions, deposited upon the teeth or in the ducts of the glands in the form of concretions or calculi, which are more or less hard and mixed with epithelial scales, lep- tothrix, and food debris. The deposit or concretion thus formed upon the teeth is called salivary calculus, or "tartar," and the concretions formed within the salivary ducts are termed salivary calculi. These deposits are found in greatest abundance upon the surfaces of those teeth which are situated opposite the ducts of the salivary glands, — viz., the buccal surfaces of the first and second superior molars, and the lingual surfaces of the inferior incisors and cuspids, and in those locations where the conformation of the teeth renders the deposits least liable to be disturbed, — viz., upon the proximate surfaces and crevices of the teeth beneath the free margins of the gums. Composition of the Saliva. — The most important constituents of normal mixed saliva are ptyalin, — a diastatic ferment, — mucin, and the 521 522 OPERATIVE DENTISTRY. clilorides of sodium and potassium ; in addition to these there are found traces of albumin, fat, potassium sulphocyanide, sulphates and phosjDhates of the alkalies and alkaline salts, principally calcic phosphate, also calcic car- bonate and oxide of iron. Occasionally there are found also, even in normal saliva, traces of urea and ammonium nitrite. The average daily amount of saliva excreted ranges from 800 to 1500 grammes, or from a little less than a quart to three pints. Tomes places it at from 13 ounces to 82 pounds. According to Lehmann, the specific gravity of the saliva ranges in health from 1004 to 1006. He states, however, that it may rise to 1008 or 1009 or even sink to 1002 without the evidence of any existing disease. According to Berzelius, normal mixed saliva gives the following analysis : Water 992.9 Solids 7.1 Ptyalin 2.9 Mucin 1.4 Sulphocyanide 1.4 Salts 1.9 According to Frerichs, — Water 994.10 Solids 5.90 Epithelium and mucus 2.13 Fat 0.07 Mucin and traces of alcoholic extract 1.41 Potassium sulphocyanide 0.10 Chlorides of sodium and potassium, phosphates of sodium and po- tassium, and oxide of iron 2.19 According to Jacobowitsch, — Water 99.51 Solids 0.49 Soluble organic bodies, ptyalin, etc 0. 130 Epithelium 0.160 Inorganic salts 0. 182 Potassium sulphocyanide 0.006 Potassium and sodium chloride 0.084 The saliva as found in the mouth is a mixed fluid, being composed of the secretions of the various salivary glands — parotid, submaxillary, and sublingual — and of the oral mucous glands, its chemic and physic prop- erties varying as the secretion from one or the other of these glands may predominate. In character it is generally a clear viscid or glairy fluid, containing epithelial cells, mucous corpuscles, and salivary corpuscles. The character, however, often varies considerably ; at times it may be a thin, watery fluid, at other times thick and ropy. DEPOSITS UPON THE TEETH. 523 The chemic reaction of mixed saliva is slightly alkaline, but when the secretions are scanty it may give a very slightly acid reaction. Saliva tested in the mouth with litmus paper often gives an acid reaction ; but this is many times due, no doubt, to the formation of acids within the mouth from the fermentative action of the acid-producing bacteria upon alimentary debris. The excretion of the parotid gland contains a trifle more water and is less viscid than the secretions of sublingual and submaxillary glands ; it contains ptyalin, but no mucin ; its calcic constituents are the carbonate and phosphate, the calcium phosphate being in minute amount. Accord- ing to Hoppe-Seyler, the inorganic elements amount to 0.34 per cent. The secretions of the sublingual and submaxillary glands are poor in ptyalin but are rich in mucin ; the sublingual contains the highest per cent. Car- bonate and phosphate of calcium are found in about equal proportions. These elements amount to about 0.43 per cent, in the submaxillary se- cretion, but the percentage is not so high in the secretion of the sub- lingual. The secretion of the mucous glands contains a large amount of mucin. The organic and inorganic constituents average about 20 parts to 1000. The calcic substances of the saliva are held in solution by the presence of a sufficient quantity of carbon dioxide (COJ. This combination, how- ever, is so unstable, that as soon as the saliva is exposed to the oxygen of the atmosphere or to the acids of fermentation produced in the mouth, or is at rest, the carbon dioxide escapes, and the calcic elements, being no longer able to maintain solubility, are precipitated and collect ujion the teeth, thus forming what is known as salivary calculus, or tartar. It is necessary, however, that the enamel be roughened or uneven, or that leptothrix threads have found attachment to I^asmyth's membrane or the enamel, in order that a nidus be presented for the formation of the concretion. The viscid tenacious character of the saliva, however, is sufficient to form a nidus for the collection of tartar upon the teeth when for any reason — but particularly in the continued fevers and other wasting diseases — the mucin becomes dried upon the teeth, forming masses of sordes. These masses of dried mucin contain innumerable epithelial scales and salivary corpuscles. See Fig. 615. It is possible, also, that the particles of the calcic deposit are held together by the agglutinating effect of the coagulated mucin. Kirk, however, believes there is a more intimate relation between the organic substances and the calcic elements of the tartar than their mere cementing properties. He thinks conditions exist which are somewhat similar to those under which calcoglobulin is formed, and suggests that salivary calculi bear a family resemblance to calcoglobulin. Salivary calculus is composed, according to Berzelius, of : Phosphates of calcium and magnesium 79.0 Salivary mucus 12.5 Ptyalin 1.0 Animal matter soluble in HCI 7.5 524 OPERATIVE DENTISTRY. According to Charles, its average composition is as follows : Calcium phosphate 55 to 64 Calcium carbonate 7 to 8 Ferric phosphate 1 to 3 Kesidue : organic matter, salts of alkalies, silica, etc 24 to 28 There is a wide difference in these two analyses, but this may possibly be explained by the difference in the location from which the sj>ecimens were probably taken. It is but natural to suppose that, inasmuch as the parotid secretion con- tains an abundance of calcium carbonate and only a minute amount of calcium phosphate, the concretions formed upon the teeth opposite Steno's duct would be composed largely of calcium carbonate ; while, upon the other hand, the concretions formed upon the lower incisors opposite the ducts of Wharton would be composed equally of calcium carbonate and calcium phosphate, as the secretions of the sublingual and submaxillary glands contain about equal portions of these salts. Magitot claimed that the salivary calculus formed in the region of the parotid glands was almost wholly carbonate, while that formed upon the inferior central incisors was largely phosphate. Alfred Vergne claimed that the calculus formed upon the superior molar teeth had less phosphate than that upon the inferior incisors, but that the carbonate was about equally distributed. Salivary calculi, or the concretions found in the ducts of the salivary glands, are iisually composed largely of calcium phosphate. They are generally of an elongated form, dirty yellow to brown in color, and are formed in concentric layers. They contain no leptothrix, and vary in size, form, appearance, and composition. The following table, prepared by Charles, gives the average compo- sition : Calcium phosphate 30 to 80 per cent. Calcium carbonate 11 to 15 " " Organic matter 5 to 12 " " Magnesium oxide, iron oxide, sodium chloride, sulphates, and potas- sium sul]3hocyanide have all been found as components of salivary calculi. Calculi composed largely of uric axiid have been found in the salivary ducts of individuals suffering from the uric-acid diathesis. Varieties. — ^It has been customary among the earlier writers to classify the varieties of salivary calculus, or tartar, according to its color and density, as though the difference in these respects was a sufdcieut ground for designating it as a separate variety. Salivary calculus varies in color from light yellow to black, and be- tween these extremes it may present any shade of green or brown. In physical characteristics it may be soft or hard, brittle or coherent, but neither of these features or characteristics is of sufficient importance, either from a pathologic or a clinic stand-point, to form the foundation of a classification. All of the differences in color may be readily accounted DEPOSITS UPON THE TEETH. 525 for by the fact tliat the micro-organisms of the mouth are capable, through their chromogenic function, of imparting to the deposits any shade of these colors ; while, upon the other hand, the ingestion of certain kinds of food and of medicines and the use of tobacco, either chewing or smoking, will also produce a change in the color of the concretions. Smoking pro- duces a black color of the tartar, but time and the action of the micro- organisms will, as in caries, produce similar dark colors. The physical characteristics are likewise governed by the element of time. Tartar that is freshly deposited is soft and yellowish-white in color, and so chalky in its nature that the slightest effort is sufficient to dislodge it in bulk ; while that which has been deposited for a much longer time will be hard and brown or black in color, and require considerable force to dislodge it. The older the deposit becomes the darker will be its color. Its density, brittleness, and coherent qualities are also dependent upon the element of time for these characteristics. Salivary calculus is formed most rapidly in a saliva which gives an alkaline reaction ; while if the secretions are acid, salivary calculus not only does not forjn, but if the reaction is decidedly acid, the tartar already formed upon the teeth may be dissolved and removed. Clinically there are three forms of salivary calculus : 1. That which is formed upon the surfaces of the crowns of the teeth, — supergingival deposits. 2. That which is formed in isolated islands, or as a narrow band at the cervices of the teeth, beneath the margin of the gums, — cervical deposits. 3. That which is formed in thin scales uj^on the sides of the root in open pockets more or less remote from the margins of the gums, — subgin- gival deposits. The first variety, or supergingival deposits, of salivary calculus is found upon the crowns of the teeth. It may be soft and friable or hard and brittle, according to the length of time which has been consumed in form- ing the deposit. Its color is usually a dirty white or yellow, but it may be any shade of green, brown, or black, according to the length of time it has been forming, the especial chromogenic bacteria present in the mouth, and the habits of the individual. This variety of tartar is clinically the most common, as well as the least harmful. It frequently accumulates in great quantities, particularly upon those teeth which are directly opjDosite the salivary ducts. Sometimes the crowns of these teeth become com- pletely covered with the deposits, so that the semblance of the tooth is lost. Figs. 616, 617, 618, and 619 show examples of such cases. Teeth which stand out of the normal line, particularly when located inside of the arch and in the lower jaw, are most often covered with such deposits ; such teeth may become so encrusted with the calcic material as to give them the appearance of necrosed and denuded bone. Such errors in diagnosis have been made, and serious surgical operations undertaken for the relief of a bone disease, which might have been prevented by count- ing the teeth upon that side of the jaw and searching for the missing ones which could not be accounted for by extraction or otherwise. The writer well remembers such a case, in which he was acting as con- 526 OPERATIVE DENTISTEY. sultant. The tumor was situated upon the left side of the lower jaw, upon the floor of the mouth, in the region of the second bicuspid, which upon examination was found missing. All of the other teeth were in normal position. The tumor was about the size of a pecan-nut and had the ap- pearance of necrosed bone, but the sensation conveyed by scratching it with a steel instrument was so different from that of dead bone that the writer was led to believe from this fact, and also from its location, which was directly beneath where the missing bicuspid should be, that the tumor was nothing more than the missing tooth, the crown of which was encased in salivary calculus. The diagnosis was proved by splitting the calculus with a chisel and mallet, when the halves fell apart, exposing the crown of the missing bicuspid tooth. The rapid formation of salivary calculus is indicative of a disturbance in the equilibrium of the metabolic process of tissue waste and repair, or, in other words, constructive or synthetic metabolism is not keeping pace with that of the destructive process. The breath and the saliva under sach circumstances have a foul and disgusting odor. The odor left upon the fingers of the operator when they have been in contact with such an offen- sive saliva is very disagreeable, indeed, and often requires repeated bathing in antiseptic and deodorant solutions before it is entirely removed. The greatest care should be exercised in sterilizing the hands and the instruments used in the treatment of such cases, as the saliva is loaded with myriads of micro-organisms, often of the most virulent varieties. Salivary calculus of the Jirst variety often presents a distinct lamina- tion which conforms to the outline of the surface upon which it was deposited. The pathologic effect of salivary calculus deposited upon the crowns of the teeth will dex3end upon the amount and the locality of the deposit. When occurring in small quantity it seems to be entirely harmless, — in fact, it seems sometimes, when deposited upon a tooth with a carious defect, that it retards or entirely arrests the progress of the caries ; many cases have been seen in which the carious cavity has been filled with salivary calcu- lus and the disease completely arrested. It must be remembsred, how- ever, that the conditions which favor the formation of salivary calculus do not favor the progress of dental caries. An alkaline condition of the saliva promotes the deposition of calcic material and retards dental caries, while an acid condition of the salivary secretions favors the progress of caries and retards or altogether prevents the accumulation of salivary calculus. When tartar of the first variety, or supergingival deposit, accumulates in large masses and impinges upon the gums, it acts as a mechanic irritant, and produces ulceration of this tissue, resorption of the alveolar plate, and recession of the gums. The accumulations may be so extensive in certain localities as entirely to, cover the teeth and to unite them into a solid mass. Such accumulations have been known to involve the six anterior inferior teeth to such ati extent as completely to destroy their attachment to the jaw and cause them to be exfoliated like a mass of necrosed bone. The second variety, or cervical deposit of salivary calculus, is found Fig. 616.— Salivary calculus. Fig. 617.— Salivary calculus. Fig. 61«. — Salivarv calculus. Fig. 619.— Salivarv calculus. Fig. C20.— Glands of Serres. X 50. DEPOSITS UPON THE TEETH. 527 upon tlie cervices of the teeth in the form of isolated islands, usually upon the lingual surface or in the form of a narrow band directly beneath the free margins of the gums. It is generally dark green or brown in color, very hard, brittle, and tenacious, requiring in some instances considerable force to dislodge it. This variety of calculus is most often found in the mouths of robust individuals, in those who live high, and those with rheumatic and gouty tendencies. The pathologic effect of this variety of calculus is to establish a low grade of chronic inflammation of the gums, ulceration of the gingival mar- gins, resorption or necrosis of the margins of the alveoli, and recession of the gums. These conditions are the result of the mechanic irritation pro- duced by the impingement of the calculus upon the margins of the gums and the pericementum. Acute inflammatory symptoms are rarely presented in this form of salivary calculus unless some traumatic injury has occurred to severely lacerate the gums, as by an unusual,' vigorous use of the toothbrush or masticating hard substances. Such an inflammation may sometimes be- come degenerative and involve the gums of both jaws and extend to the hard palate, producing an obstinate ulcerative stomatitis. The presence of these concretions rarely produces a diffuse inflamma- tion of the pericementum. The inflammation is usually confined to that location which is the direct seat of the irritation, — viz., the margins of the gum and the pericementum. These tissues are gradually destroyed by the encroachment of the deposit and the consequent inflammation and ulcera- tion produced by their presence. This variety of salivary deposit seems to accumulate most rapidly after a chronic inflammatory process has been established in the free margins of the gums. This led Serres and some other pathologists to the supposition that the glandular structures of the gums (glands of Serres, Fig. 620) were instrumental in causing the formation of the deposits. This ques- tion has, however, not been satisfactorily settled. The general opinion seems to be, however, that the deposits come directly from the salivary secretions, and that the inflammatory conditions of the gingivae resulting from the mechanic irritation present in some way — perhaps through cer- tain products of the decomposition of tissue, NH3 and H^S — more favorable conditions for the deposition of the calcic material found in the saliva than would be the case under other circumstances, hence its more rapid accu- mulation. The third variety, or subgingival deposit, is that which is found in thin scales upon the sides of the roots of the teeth in open pockets more or less remote from the free margins of the gums. This form of deposit and its effect upon the pericementum and the surrounding tissues will be dis- cussed in the chapter on pyorrhoea alveolaris. Treatment.— -The treatment of the supergingival deposits, or ordinary • form of salivary calculus, and of the cervical variety consists in removing the concretions from the surfaces of the teeth by the aid of various instru- ments known as scalers. These instruments are made with suitable curves and angles adapted to reach every portion of the various surfaces of the 528 OPERATIVE DENTISTRY. tooth-crown, while the blades are of such form and temper that the edges can be kept sharp. Fig. 621 illustrates a few of the most useful shapes employed for this operation. Some of these instruments are intended to Fig. 621. Small scalers. be used as chisels, others as hoes or scrapers. The operation consists of first scaling or scraping away the accumulated mass of tartar, and after- wards thoroughly polishing the exposed surfaces of the teeth with pulver- ized pumice. This part of the operation may be done with any orange- FiG. 622. wood wedge-stick flattened at one end or by variously shaped rubber disks, wheels, and cups, or with small brushes, as shown in Figs. 622 and 623, used in the. dental engine. Fig. 623. After the concretions have all been removed, the mouth should be thoroughly irrigated with a soothing antiseptic mouth- wash, like listerine, pasteurine, borolyptol, etc., followed by the spray from an atomizer DEPOSITS UPON THE TEETH. 529 charged with the same solution, which should be directed into the inter- dental spaces to make sure that all loose particles of tartar are removed from between the teeth and from beneath the margins of the gums. Finally, to relieve any inflammation that may be present and to promote the healing of the gums, they may be painted with a combination of the tinctures of iodine and aconite in equal parts. The prevention of the further accumulation of salivary calculus will depend largely upon the time which the individual is willing to give to the cleansing of the teeth. Thorough brushing of the teeth after each meal with a suitable dentifrice and the judicious use of floss-silk and tooth-picks will usually prevent the further accumulation of deposits upon all accessi- ble surfaces. The prevention, therefore, of the accumulation of salivary deposits sums itself up into the question of cleanliness. Many refined people who are extremely neat in every other respect often present mouths which are positively disgusting to behold, but whose sense of refinement would be greatly shocked if they were told that their mouths and teeth were in a very filthy condition, and that they carried about in their oral cavities conditions which were more fatal to good health than the presence of sewer gas in their dwellings. 34 CHAPTEE XXXVIIL PYOEEHCEA ALVEOLARTS. Definition. — Pj^orrhoea (Greek -nbov^ pus ; poia, a flow). A purulent discharge. Alveolaris (Latin, a small hollow). Pertaining to the alveoli, or the sockets of the teeth. The term, therefore, means a flow of pus from the alveolus of a tooth. But as this is a symptom of several other diseases which involve the same tissues, — viz., alveolar abscess, traumatic perice- mentitis, scorbutic pericementitis, mercurial pericementitis, etc., — the term does not seem to be well selected to express the characteristic pathologic features of the disease. The term pyorrhoea alveolaris has, however, been quite generally adopted by the profession, and for that reason it is perhaps better to retain it, although several others have been suggested which are more appropriate, as they convey a better idea of the true nature of the disease. Synonymes. — Riggs's disease, suppuration conjointe, pyorrhoea inter- alveolar- dentaire, gingivitis expulsiva, osteo-periostiti-alveolo-dentaire, pyorrhoea alveolo, caries alveolaire specifica, cemen to periostitis, infectoso- alveolitis, periostitis dentalis, periostitis-alveolo-dentalis, calcic pericemen- titis, phagedenic i^ericementitis, gouty pericementitis, ptyalogenic calcic pericementitis, hsematogenic calcic pericementitis, blennorrhoea alveolaris, interstitial gingivitis. The various terms or synonymes which have been applied to this affec- tion express in a certain sense the views held by the writers who have sug- gested them, as to the nature of the disease. Pyorrhoea alveolaris is a disease ^hioh primarily affects t\iQ pericertientum, manifesting itself in a suppurative inflammation, sometimes acute in form, but generally of a chronic type ; and, secondarily, the inflammatory process involves the walls of the alveolus and the gum. This process is accompanied by loosening and turning or extrusion of the teeth, a discharge of pus from the alveolus, gradual disintegration of the alveolar process (caries), reces- sion of the gums, and finally the tooth loses its alveolar and gingival connection and falls out. Upon the loss of the tooth the inflammatory symptoms immediately subside, which proves conclusively that the local manifestations of the disease are primarily associated with the dental tissues, and not with the gingivae or the alveolar processes. Witzel and others have maintained, however, that the disease was primarily located in the alveolar border, and that the gum and pericemen- tum were involved as a secondary feature of the disease. Pyorrhoea alveolaris, next to the subject of dental caries, has attracted more attention from dental surgeons than any other affection of the human mouth. It has been thought to be a disease of modern origin and a result of the sins of our modern civilization ; but a visit to the ethnologic depart- 530 , PYOEEHCEA ALVEOLARLS. 531 ments of our large museums will convince any one that the disease is not confined to modern times nor to higher civilization, but that in all prob- ability it is as old as the human race. Evidences of the disease are to be seen alike in ancient and modern skulls, in the skulls of aboriginal tribes, and also in those of barbarous, semi- civilized, and civilized nations. On the other hand, however, there seems to be some reason for believing the disease to be on the increase among civilized nations of the present day. Whether this is a fact or not remains yet to be proven. Statistics are necessary to establish such a fact, and these have not been gathered. This statement, however, seems quite true, — viz., the dental surgeon is called upon to treat more and more of these cases every year. Perhaps this is due to his better general knowledge of the disease, and to his ability to recognize its clinic aspects and manifestations not only in the fully developed disease but in its incipient stages ; or it may be possible that the disease is sometimes confounded with other affections which present somewhat similar symptoms and pathologic features. It is no uncommon thing for a chronic alveolar abscess which is discharging through the alveolus to be mistaken in a hasty examination for a case of pyorrhoea alveolaris, and vice versa. It therefore becomes exceedingly important that every examination should be made with the utmost care and precision, that errors in diagnosis may be avoided. Causes. — A wide difference of opinion exists among pathologists and dental practitioners in reference to the etiology of this disease. So much interest has been taken in the study of this subject in recent years that the literature upon the etiology of the disease has become quite voluminous, and nearly -as confusing. The writer has found, however, that after a careful review of the literature these opinions can all be grouped under three heads : 1. That the disease originates in some constitutional state or dyscrasia. 2. That the disease is caused entirely by local irritation and environment. 3. That the disease is due to the infection of the tissues with micro-organ- isms. Constitutional Origin of the Disease. — Fanchard (1746)* was the first to call attention to the disease and record its essential clinical features, but offered no opinion as to the origin of the disease, neither did he desig- nate it by any specific term. Jourdain (1778) f published a communication describing the disease, and made the suggestion that it was of scorbutic origin, and termed it in its later stages ^^ conjoined suppuration,''^ because it is then complicated with a purulent discharge from between the margins of the gums and the cervices of the teeth and a gradual destruction of the alveolar processes. Toirac (1822), J in his communication upon the disease, termed it ^^pyorrhoea-inter-alveolo-dentaire," but failed to offer an opinion upon the oriffin of the disease. * Independent Dental Journal, 1875. t Philadelphia Journal of Medical and Physical Sciences, 1821. X Journal of the American Medical Association, 1879. 532 OPEEATIVE DENTISTRY. Bell (1829)* described the disease in all of its clinical features, and divided the affection into two distinct forms, one dependent upon the formation of deposits upon the teeth, the other caused by a constitutional condition which may be looked upon as a sort of premature old age. He says, ''In forming a judgment upon cases of this description, however, and even upon those in which the loss of substance is associated with more or less of diseased action, it is necessary to recollect that the teeth are generally removed in old age by this identical mode, — namely, the de- struction of their support by the absorption of the gums and the alveolar processes ; and as this step towards general decay commences at very different periods in different constitutions, it may doubtless in many cases, even in persons not past the middle period of life, be considered as an in- dication of a sort of premature old age, or an anticipation, at least, of senile decay, as far as regards these parts of the body." Harris (1853) f termed the disease a " chronic inflammation of the gums,^' dependent upon morbid constitutional conditions as predisposing causes, such as ' ' bilious and inflammatory fevers, the excessive use of mercurial medicines, the venereal virus, intemperance, and debauchery ; while any deterioration of the fluids of the body is peculiarly conducive to it. Per- sons of cachectic habit are far more subject to it, and generally in the worst forms, than those individuals in the enjoyment of good health." As im- mediate or exciting causes he mentions the "local irritation of salivary calculus, carious, dead, loose, or aching teeth or roots of teeth, or teeth which occupy a wrong position or that are crowded in their arrangement." Marechal de Calvi (1860) ;|: looked upon the disease as an hereditary constitutional disorder, and termed it gingivitis expulsiva. Magitot (1867), § in his admirable paper upon the nature of the dis- ease, describes it as a slow but progressive inflammation causing the destruction of the periosteal membrane and the cementum, which begins at the cervix and extends to the apex of the root, and involves the loss of the tooth. The term by which he designated the disease was ' ' osteo- periostiti-alveolo-dentaire," as this was the exact seat of the disease. He believed the disease was primarily located in the j)ericementum, and that soon after the apxjearance of the inflammation in the membrane the gums and osseous walls of the alveolus became involved, but that the disease was never primarily located in those latter tissues. He viewed the causes of this peculiar inflammation as very complex. In his opinion the origin of the disease lay in a faulty general nutrition. Persons of a gouty and rheumatic diathesis furnished the greatest number of cases, but it was also very common in individuals suffering from dia- betes mellitus, albuminuria, and ansemia. The formation of calcic deposits upon the teeth he regarded as purely accidental and playing no important part in the etiology of the disease. He * Anatomy, Physiology, and Diseases of the Teeth, t Dental Surgery. X Journal of the American Medical Association, 1897. ? Etudes et Experiences sur la Salive, Paris. PYORRHOEA ALVEOLARIS. 533 advised, however, as an indispensable preliminary to any form of treat- ment, the thorougli removal of all concretions upon the roots of the teeth. Wedl (1870),* in describing the disease, says, ''That portion of the root-membrane which is in relation with the submucous connective tissue of the gums appears to be attacked secondarily in most cases, in conse- quence of the extension of the disease, either from the enclosed extremity of the root-membrane or from the inflamed gums. In these cases the gum becomes detached from the neck of the tooth, and pressure upon the alveolus forces out a puriform fluid. This condition results, without notable pain, in the loss of the affected tooth." In reference to the causation of the disease he says, "In these cases, then, we have to do, first of all, with a catarrhal inflammation of the gum, which afterwards extends to the root- membrane." Brown (1870) f was the first to suggest that the disorder was due to the formation of certain deposits upon the roots of the teeth, which were derived from the serum of the blood, and which he denominated serumal calculus. Salter (1875) J denominates the disease "false scurvy,^ ^ and believes it is more or less the manifestation of constitutional vice, being frequently associated with chronic dyspepsia and general ill-health, 'and as a result in females of frequent pregnancies. Certain drugs, like mercury and iodide of potassium, when given to excess have the power of producing the disease. Sirlette (1876), § in discussing the etiology and pathology of this dis- order, stated that he regarded the disease as due to certain constitutional conditions, such as rheumatism, scrofula, syphilis, diabetes' mellitus, albu- minuria, etc., but that certain local conditions acted as exoitiag factors. He denominated the affection ''periostitis-alveolo-dentalis." Taft (1876) 1 1 regarded pyorrhoea alveolaris as arising from a general disorder of health, and unless the general state of the health was improved, local treatment would be of no avail. Eehwinkle (1877),^ in a paper upon the "Causes and Treatment of Pyorrhoea Alveolaris, ' ' says the origin of the disease can often be traced to the action of mercury, and in other cases to constitutional and inherited predisposition, while it often exists independently of foreign deposits and in the cleanest of mouths. Davis (1879),** in a paper on "Gum and Alveolar Diseases," says he is unable to account for the phenomena of Eiggs's disease, except upon the hypothesis of atrophy of the peridental membrane or of the external fibrous covering of the alveolus, while the deposits which are found upon the roots of the teeth are an accidental sequence, and not a cause of the disease. * Pathology of the Teeth, t American Journal of Dental Science. X Dental Pathology and. Surgery. § Gazzetta Medica di Eoma, 1876. II Operative Dentistry. Tf Dental Cosmos vol. xix. ** Ibid. 534 OPERATIVE DENTISTRY. Cowles (1879),* in a discussion upon the subject of "Eiggs's Disease," said, "Wedging is a great producer of this difaculty, and therefore I am opposed to wedging, but a more general cause than all others is the lack of nutrition in the parts." Bssig (1879) t expressed the opinion that the primary cause was prob- ably systemic ; that it usually makes its appearance in mouths which were remarkable for an almost complete immunity from dental caries ; and this fact has led to the assumption that such evident power of resisting the usual causes of decay until middle life implies extreme density and low degree of vitality in the structure of the teeth, resulting in a final sever- ance between them and the more highly vitalized contiguous parts, thus constituting a x)redisposing cause of a disease liable to be developed by an accretion of calculus or other excitant. The disorder, he thinks, is a local manifestation of a constitutional cause, and the calcareous deposit merely an accident of opportunity. Serran (1880) J believed that the primary manifestation was a local con- gestion of the gums, followed by an inflammatory exudation in the peri- dental membrane, loss of vitality in the structure, the formation of pus, and all of the other symptoms and pathologic features which are charac- teristic of the disorder. He recognized the fact, however, that the disease was most common in the middle period of life, and that individuals suffer- ing from gout, rheumatism, diabetes mellitus, and albuminuria furnished the principal number of cases. These statements were in certain respects in opposition to the views expressed by Magitot in 1867 relative to the tissues which were primarily involved in the disease. A commission appointed by the Societe de Chirurgie to consider the statements of Serran denied the gingival origin of the disease, and sub- stantially upheld the views of Magitot. Mills (1880) § claimed that the cause was systemic, and the deposit only a local manifestation. He believed, also, that age was not the only factor in the production of the disease, but that various influences, physical and mental, were often powerful abettors of the disease. Conditions of ner- vous exhaustion may exist at certain periods of life, permitting the local expression of a disease which altered circumstances in after-life may radi- cally modify. In his opinion the disease not infrequently appeared in the mouths of youths, generally as a sequence of one of the eruptive fevers. Atkinson (1881) || was of the oj)inion that the disease was of consti- tutional origin, the result of nervous debility or original defective innerva- tion, and the deposit a sequence of the disorder, but never the cause. Coles (1881) ^ was of the opinion that certain systemic conditions acted as predisposing causes, and micro-organisms as local exciting causes. Ingersoll (1881),** in a paper upon "Sanguinary Calculus," maintained * Dental Cosmos, vol. xxi. t Ibid., vols, xxii., xxiii. ' t Bulletins et Memoires de la Societe de Chirurgie, tome vi. p. 411. § Dental Cosmos, vol. xxiii. • || Ibid. If International Medical Congress, 1881. ** Ohio Dental Journal, 1881. PYORRHCEA ALVEOLARIS. 535 that certain concretions were formed upon the roots of teeth which could not be derived from the saliva, as they were formed near the apex of the root, and under circumstances which made it impossible that they could be of salivary origin. This form of calculus contained a dark coloring matter, and was always found in connection with ulceration and a discharge of pus. The liquor sanguinis contained the lime-salts in solution, and these were crystallized and deposited upon the roots of the teeth. As this form of concretion could not have come from the saliva, he con- cluded that it must have come from the blood, and he therefore termed it sanguinary calculus. This opinion is very similar to that expressed by Brown in 1870, which has already been quoted. Eawls (1885) * believed the causes were primarily of systemic origin, as expressed in inherited and acquired tendencies, habits, and environ- ment. Malarial fever, mercurial ptyalism, etc. , and the excessive use of sodium chloride were all important factors in the production of the disease. Eeese (1886) f was of the opinion that the disease was due to the pres- ence of the uric acid diathesis resulting from the abuse of alcoholic stimu- lants. Patterson (1886) % revived the theory of Wedl that the disease was due to a catarrhal condition of the oral mucous membrane and the gingivae (oral catarrh). Patterson also believed that pyorrhoea alveolaris, like catarrh, was contagious, and sometimes even epidemic. Farrar (1886) § looked upon the disease as being the result of a combi- nation of systemic conditions and tendencies and local irritants, and held that there was a peculiar systemic condition associated with hypersecretion and an increased amount of earthy deposits. Starr (1886) 1 1 regarded the disease as due to certain systemic conditions and tendencies, and associated with some undetermined local irritating factor. He was of the opinion that this local factor was the same as that which caused hypercementosis. He also stated that in his experience a majority of the teeth affected with pyorrhoea alveolaris were found in the upper jaw. Sudduth (1887)^ expressed the opinion that pyorrhoea alveolaris was a sequel, or rather the secondary stage, of a disease which had its inception in a catarrhal stomatitis. In fact, he thinks he is justified in classing the disease as a localized catarrhal stomatitis which is dependent upon hered- itary dyscrasia for its constitutional factor. The disease may be either acute or chronic. Sutton (1887) ** regards the disease as undoubtedly of constitutional origin, as expressed in gout, rheumatism, mollities ossiura, and other wasting diseases. * Dental Cosmos, vol. xxvii. t Transactions of the Louisiana State Dental Society, 1886. % Dental Cosmos, vol. xxvii. § Independent Practitioner, vol. vii. || Ibid. \ Sajous's Annual, 1888, vol. iii. ** Dental Record, 1887. 636 OPERATIVE DENTISTRY. Marshall (1891) * expressed the opinion that in many cases the origin of the disease could be traced to the rheumatic and gouty diathesis, and that the deposition of the concretions upon the roots of the teeth in those localities not easily reached by the saliva, or in which the presence of the saliva would be an impossibility, is due to the same cause which produces the chalky formations found in the joints and fibrous tissue of gouty and rheumatic individuals, and suggested that these deposits were formed of urates of lime and soda. Pierce (1892, 1894, and 1895) f in a series of papers presented a num- ber of clinic and pathologic facts which in their totality seemed to estab- lish the kinship between pyorrhoea alveolaris, or hematogenic calcic peri- cementitis, and the systemic condition generally recognized as the gouty or uric acid diathesis. Darby (1894) X strongly upheld the theory of the constitutional origin of the disorder, and ascribed it to the uric acid diathesis. Burchard (1895) § believed the disease to be due to constitutional and local predisposing causes and to local exciting causes. Among the consti- tutional predisposing causes he mentions hereditary influences, particu- larly arthritic diseases and the diseases of suboxidation and faulty elimina- tion ; among the local predisposing causes are overuse, disuse, and misuse of the teeth. These also often act as direct exciting causes. Subgingival deposits also act as exciting causes. 0. H. Tomes (1897) 1 1 regards the causes and pathology of the disease as very obscure. There is much to support the idea tliat a constitutional cause is at the bottom of it, — for instance, it usually occurs with some near approach to bilateral symmetry, and the teeth first affected are often not those most liable to the deposit of tartar, — while he assigns to tartar a merely secondary influence in the progress of the disease which comes into ojDeration only after the mischief has begun. He does not, however, subscribe to the uric acid theory. Harlan (1898) ^ regarded the disease as being largely influenced by heredity and acquired conditions, deposits acting as exciting causes. Ehein (1899) ** divides the disease into pyorrhcea simplex and pyorrhoea complex. The former he believes is caused entirely by local irritants, the latter by constitutional conditions, such as malnutrition, improper elimi- nation, uric acid diathesis, etc. Kirk (1899), ft recognizing the constitutional origin of the disease, says, ^'It is to the class of non-bacterial inflammatory tissue reactions that phagedenic pericementitis in its earlier stages belongs, and that the toxic irritant is the group of alloxuric bodies which, like their congener uric * Transactions of the American Medical Association, 1891. t International Dental Journal, vols, xiii., xv., xvi. X Ibid., vol. XV. § Dental Pathology, Therapeutics, etc. II Dental Surgery. \ Dental Cosmos, vol. xl. ** Dental Review, 1899. tt International Dental Journal^ vol. xx. PYORRHCEA ALVEOLARIS. 537 acid, are waste products of nitrogenous metabolism, and as a result of improper elimination find their way into the blood-stream and thence to the membranous investment of the tooth, that are the active causes of de- generation of the tissue in question, and, should the irritative influence be of sufficient intensity as related to the vital resistance of the elements of the membrane, may and do cause its molecular necrosis with attendant inflammatory reaction." Fitzgerald (1899) * claimed that the production of pyorrhoea alveolaris depended upon a constitutional predisposing cause and an exciting cause in the form of a local irritation. The predisposing cause might be tuber- culosis, syphilis, scurvy, the exhaustion following acute infectious diseases or any other source of maluurition. The exciting cause is usually a gin- givitis induced by several forms of local irritation. He also recognized a gouty origin of the disease in which the local necrosis of the pericementum is caused by gouty disease of one of the blood-vessels in its substance. Talbot (1899) f terms the disease interstitial gingivitis, and says the causes are divisible into predisposing and exciting, the predisposing causes being again subdivided into local and constitutional. As predisposing factors of the disease he mentions conditions of jaw evolution, the transitory nature of certain structures, degeneracy, and conditions of previous irritation and inflammation. The exciting causes are either constitutional or local, but, as a rule, are local or have a local action. He thinks calcic deposits are a result and not a cause of the disease. Local Origin of the Disease. — Koecker (1821) | regarded the dis- ease, which he called inflammation of the gums, as one of local origin, and caused by the irritating effects of tartar. He said, ^'In all the various forms of the affection which he had observed he had never seen a case in which tartar was not present. . . . Persons of robust constitution are much more liable to this affection of the gums than those of delicate habit, and it shows itself in its worst form after the age of thirty offcener than at any earlier period." Bromwill (1867) § was of the opinion that the cause of the disease was a local one, due to the thinness of the alveolar process between the teeth, which deprived the peridental membrane and the gum of proper support. Malocclusion of the teeth also exerted an influence by establishing inflam- mation. Eiggs (1875) 1 1 was very emphatic in his opinion that the disorder was due entirely to the local irritation of salivary calculus, which was deposited at the necks of the teeth just beneath the free margin of the gum, and extended from there towards the apex of the root, causing inflammation of the gum and peridental membrane, necrosis of the edge of the alveolus, a discharge of pus, and recession of the gums. * Clinical Journal, March, 1899. t Interstitial Gingivitis, 1899. X Principles of Dental Surgery. § Dental Cosmos, vol. xxiv. II Transactions of the American Academy, 1875. 538 OPERATIVE DENTISTRY. Sliieff (1875),*of Vienna, was of the opinion that the disease had its apparent origin in local irritants induced by mechanic, chemic, and thermic changes. The real origin of the disease, however, was often very obscure. The influence of the rheumatic diathesis was doubtful. Niles (1880) f supported the theory that salivary calculus was the pri- mary cause of the disease. But in certain cases there was a constitutional condition or diathesis in which there was an excess of phosphates and carbonates of lime in the circulation, and this condition exerted an in- fluence in the production of the disease. This condition or diathesis was probably due to dyspepsia, excessive fatigue, mental or physical overwork, protracted illness, or any unusual strain on the system. He thought it safe to say that ninety-five per cent, of the cases seen in private practice are ^^ due to the deimsit locally of lime-salts ahout rough surfaces on the teeth, the nucleus being usually at the point where the enamel joins the cementum." Walker (1881), | in a paper upon the disorder, expressed the opinion that its origin was local, and that the starting-point of the disease was to be found in a subacute inflammation of the gum which passed into the depths of the alveolar process. Witzel (1882) § regarded the disease as a purely local affection, having no constitutional relations whatever. He asserted that the primary origin of the disease was an inflammatory condition of the alveolus^ accompanied by caries of the border and followed by a deposit of calcic material just beneath the free margin of the gum, which caused the gingivae to become retracted and reverted. The infection of the carious material with micro- organisms developed pus, which became infectious to a greater or less extent-. He therefore termed the disease "infectious alveolitis," and de- scribed it as a molecular necrosis of the alveoli, or caries of the dental sockets, produced by septic irritation of the medulla of the bone. Black (1886), 1 1 in a most exhaustive article, gives it as his opinion that pyorrhoea alveolaris is a local disorder. He, however, describes two forms of the disease ; one he terms calcic inflammation, the other phagedenic peri- cementitis. The former he believed to be due to calcic material dei30sited at the necks of the teeth, which gradually encroached upon the peri- cementum, establishing suppurative inflammation, while the latter form was characterized by a phagedenic state, — or destructive ulceration of the gingivae, — and destruction of the peridental membrane and alveolar walls. He thinks this destructive inflammation of the peridental membrane is distinctive from other inflammations of this tissue, and that a serumal cal- culus may be associated with its origin. He looks upon the disease as having its primary origin in the peridental membrane rather than in the alveolus, although the destruction of these tissues apparently goes on together. * Wiener med. Presse, vol. xvi. t Dental Cosmos, vol. xxiii. X Transactions of the International Medical Congress, 1881. § British Journal of Dental Science, vol. xxv. II American System of Dentistry, vol. i. PYOERHOEA ALVEOLA RIS. 539 Talbot (1886) * stated that it was his opinion that the disease was a local one, witli both local and constitutional causes. He believed the dis- ease began as a simple inflammation of the gums which later became chronic. Sudduth (1894) f offered the suggestion that the principal exciting cause of pyorrhoea alveolaris was the lactic acid formed in the mouth by fermen- tation. Arrington (1900) J takes an extreme view of the origin of the disease, and maintains that there is but one form^ although there are sundry feat- ures that present as the disease progresses. He believes that it is not dependent upon any particular state of the system for its origin, for all individuals alike, the robust and the feeble, seem to be equally subject to it ; nor is it a consequence of, or in any way complicated with, any other disease. Bacterial Origin of the Disease. — Archovy and Izklai (1881), § in discussing Dr. Walker's paper, read at the International Medical Congress, London, both ascribed the disorder to parasites or minute organisms. Archovy (1884) || shared the opinion of Witzel, that the disease was a marginal necrosis of the alveolus, caused by a septic irritation, probably the result of minute organisms. He termed the disease caries alveolaris specijica. '^The nature of the affection is that of a suppurative inflam- mation which spreads to all parts lying between the gum and the dentin of the root." Malassez and Galippe (1884) considered the disease as undoubtedly of parasitic origin, ''which may be proved by an examination of stained sections ; by cultivation and isolation of the parasites contained in the dental tubules ; by the contagion spreading from tooth to tooth, as well as from individual to individual, as we observed more than once in persons of different sex who stand in intimate relations to each other." Galippe (1888) ^ thought he had found the specific organism of the dis- ease, which was designated by the Greek letters rj and /?. Galippe' s claims have not been substantiated by later observation and research. Magitot,** in reviewing the labors of Malassez and Galippe, does not combat the theory of the parasitic nature of the disease, and concludes his remarks with three propositions : 1. The affection characterized by alveolar suppuration and by loosen- ing and falling out of the teeth should be designated as a true sympto- matic alveolar arthritis, septic and contagious. 2. It generally arises under the influence of certain unfavorable con- ditions of health and diathesis, also in exanthematic fevers, etc., where it manifests itself either as a complication or as a consequence. * Dental Cosmos, vol. xxviii. t Ibid., vol. xxxvi. % International Dental Journal, July, 1900. § Transactions of the International Dental Congress, 1881. II Diagnostik der Zahnkrankheiten, 1885, S. 232. \ Die infectiose arthro-dentare Gingivitis, 1888. *^ Miller's Micro-Organisms of the Human Mouth, p. 324. 540 OPERATIVE DENTISTRY. 3. The therapeutics should consist chiei3y in the application of anti- septics, local alteratives, astringents, or caustics. Miller (1890) * was unable to discover any specific micro-organism in the pus discharged from cases of pyorrhoea alveolaris. Out of twenty- six different cases examined, twenty-two different kinds of bacteria were found. In cases 8 and 13, and in 16 and 17, the bacteria were found to be identical. He therefore concludes that there is no specific bacterium yet found for this disease, as the four cases in which the bacteria were iden- tical proved nothing. But if there is such an organism, it will not grow on gelatin, and he suggests that in further experiments media should be selected which can be kept at the temperature of the mouth. It may be possible, however, if such a bacterium exists, that, like many other mouth bacteria, it is not cultivable on any of the artificial nutrient media. Whittles (1898) f says that in all genuine cases of pyorrhoea alveolaris which he has examined he has found in the pus a ' ' particular bacterium which is probably of the anaerobic variety." The discovery of this organism, which, by the way, is not described, led him to search for an efiicient antidote, which he found in the "green iodide of mercury," triturated in a mortar with a little glycerol to allow of greater readiness of application to the sulci or pus pockets of the affected teeth. He looks upon the disease as another example of those affections which accompany a general lowered condition of the mesoblastic element as a predisposing cause, the real excitant being a bacterium. Younger (1900) J thinks that Cook has discovered a specific organism for the disease, as a certain form was constant in his cultivations. No definite description is given of the organism, as it was still under culti- vation and observation. From the foregoing resumS of the theories which have been advanced to account for the origin of pyorrhoea alveolaris, and the facts which have been deduced by observation and experiment, it is evident, that such diverse etiologic factors cannot all of them be the real cause of a single form of the disease. There is no doubt that a considerable number of cases of the affection are due primarily to certain acquired systemic conditions, like syphilis, mercurialism, iodism, anaemia, dyspepsia, scurvy, malaria, typhoid fever, diabetes mellitus, albuminuria, etc., or to inherited disease, like congenital syphilis, or to inherited tendencies to diseases like tuberculosis, gout, and rheumatism, which induce trophic changes in the tissues and establish a predisposition to early senile degenerations ; while, upon the other hand, a considerable number of cases are due entirely to certain local irritative conditions induced hy the formation of salivary concretions deposited at the cervices of the teeth and upon the sides of the roots, which by their en- croachment upon the pericementum induce inflammation of a suppurative character, accompanied in its later stages by ulceration of this membrane, disintegration of the alveolar border, and recession of the gum. * Micro-Organisms of the Human Mouth. t Dental Cosmos, vol. xl. % Ibid., 1900. PYOREHCEA ALVEOLARIS. 541 It is a very doubtful supposition, however, tliat the disease is ever caused primarily by infection of the tissues with the pyogenic cocci, or by any specific bacterium. It would seem more probable that the infection was a secondary factor or exciting cause, while the primary cause was a lowered vitality of the tissues, due to some previous or exciting systemic condition, or to injury by local irritants, which had placed the parts in such a condition that they were unable to resist the action of the pyogenic micro-organisms which are always present in the mouth. The disease may therefore be divided into three general forms, — one arising from purely local causes, the others from constitutional or systemic conditions, the first of which may be termed, as suggested by Peirce, ^^ptya- logenic calcic pericementitis ;" the second, ^ ' hcematogenic calcic per Icementitis f^ and the third, '■^ phagedenic pericementitis,^^ as suggested by Black. PTYALOGENIC CALCIC PERICEMENTITIS. Causes. — This form of the disease has its origin in those systemic and local conditions which are thought to produce inflammation of the gums. These causes are predisposing and exciting, general and local. Dental pathologists are inclined to divide inflammation of the gums into two dis- tinct forms, one which is general in its character and termed gingivitis or ulitis, and another which is confined to the borders or margins of the gums and termed marginal gingivitis. Marginal gingivitis is often catarrhal in character, and may be asso- ciated with catarrhal stomatitis, and not infrequently precedes ulcerative stomatitis. In this form of gingivitis ptyalogenic calcic pericementitis is thought to have its origin. The predisposing causes of marginal gingivitis are general and local. The general predisposing causes are those conditions which are associated with a faulty metabolism, — conditions which lower the vital resistance of the tissues and predispose them to inflammation, suppuration, and various degenerative changes. The local predisposing causes are lack of exercise and the impaction and decomposition of food debris. The local exciting causes are various irritants of a mechanic, chemic, and septic nature, like harsh brushing, salivary calculus, irritating drugs, and micro-organisms. The presence of a marginal gingivitis, either local or general in char- acter, presents the most favorable conditions for the establishment of ptyalogenic calcic j)ericementitis that could possibly be arranged, for by the swelling and loosening of the gums at the cervices of the teeth pockets or sulci are formed for the lodgement of debris, while the tenacious pro- duct of the mucous glands— mucin — acts as a nidus for the formation of subgingival deposits, which "are produced by precipitation of the calcic material held in solution in the secretions through the action of the products of fermentation upon these fluids ;" * and thus the calcic mate- rial is deposited in the pockets, and by reason of the fact that it remains undisturbed in these locations it accumulates more or less rapidly and * Dental Cosmos, vol. xxxvi. 642 OPERATIVE DENTISTRY. becomes very dense. Its peculiar density is due to the fact tliat it con- tains less food debris and leptothrix than the common form of salivary calculus. Pathology and Morbid Anatomy. — Ptyalogenic calcic pericementitis is characterized by the presence of subgingival calcic concretions, dark green in color, very hard, and deposited in the form of thin scales u^Don the sides of the roots in open pockets, beginning at the cervix and extend- ing in a direction towards the apex. The formation of this deposit is doubtless due to a catarrhal condition of the mucous membrane of the mouth, resulting in a marginal gingivitis. The calcic material is derived partly from the salivary secretions and partly from the exudations and abnormal secretions of the mucous membrane and the gums. The effect of this deposit when once formed is to establish a continuous irritation of the margins of the gums, thus keeping up the inflammation and exciting degenerative changes not only in this tissue but also in the pericementum and alveolar border. The existence of a persistent mechanic irritation causes in this case a chronic hypersemia of the gum and pericementum, which lowers the vital resistance of these tissues and places them in a condition to be readily acted upon by the pyogenic micro-organisms which are always present in the food debris and mixed secretions of the mouth. As a result of the inflamed condition of the margins of the gums they become swollen and everted, forming a space, sulcus, or pocket between the tooth and the gum, to which the altered secretions, food debris, and the saliva have free access. Precipitation of calcic material takes place, probably as a result of the products of fermentation coming in contact with the fluids of the mouth which hold the calcium salts in solution, and thus little by little the concretions are built up. " Burchard* says, ''It is probable that these deposits have their origin in a reaction between the altered mucous secretion of the gingival glands and the products of lactic fermentation, their calcic salts being derived from the saliva." The calcic deposits which are found upon the sides of the roots of the teeth at remote points from the margin of the gums, but which are in communication with the secretions of the mouth through open pockets, are productive of great damage to the integrity of the peridental tissues, sometimes causing acute diffuse suppurative inflammation and destruc- tion of the pericementum, or of chronic inflammation and ulceration of the gum and pericementum, with a discharge of fetid pus, necrosis of the alveolar border (caries), and resorption of the gum. In the first or acute form of this inflammation the process of destruc- tion in the tissues is often very rapid, a few weeks or months only being required to cause complete exfoliation of the tooth, unless the concretions are removed ; and even then the inflammatory symptoms do not always subside nor the pockets close, but resist all treatment and remain in a * Pathology, Therapeutics, and Pharmacology. PYOERHCEA ALVEOLARIS. 543 state of subacute inflammation, tlie pericementum thickened, tlie tooth loosened in its alveolus, and gradually extruding or turning upon its axis, while it becomes more and more a source of irritation and annoyance to the patient until it is extracted or exfoliated. In such cases, however, there is always associated with it some peculiar systemic condition or dyscrasia, like tuberculosis, syphilis, diabetes, albu- minuria, or anaemia, which aggravates the local conditions and retards or prevents the healing process. In the second or chronic form of the inflammation the process of de- struction in the pericementum and the surrounding structures is much less rai^id and the symptoms are all less aggravated, and whereas in the acute form of the inflammatory process the tooth may be exfoliated in a few weeks or months, in the chronic form of the disease this process may be extended over as many years. A large per cent, of the latter cases are amenable to surgical treatment, and these are the cases of pyorrhoea alveo- laris which are so often advertised as cured. The cause of irritation is a purely local one, — a mechanic irritant ; therefore when the cause is removed and the parts are assisted in the healing process a cure takes i^lace. In many of the remaining smaller per cent, of cases, which do not readily respond to treatment, there is often a history either of gout, rheu- matism, malaria, anaemia, leukaemia, nephritic diseases, physical, nervous, or mental debility, reflex neurosis, or in married females of frequent preg- nancies or prolonged lactations. Sometimes local conditions are present which produce over-stimulation or under-stimulation of the circulation of the pericementum, like malocclusions of the teeth, or loss of occlusion, which would in the one case predispose them to hypersemia and inflamma- tion of the pericementum, and in the other to atroi^hy, thus lowering the vital resistance of the tissues and preparing the way for the destructive action of the pyogenic micro-organisms. The individuals who are the most liable to suffer from this form of pyorrhoea alveolaris usually possess teeth of finely organized structure, which are very resistant to cutting instruments and singularly free from dental caries. These facts were noticed by the earliest writers upon the disease, and were classed by them as predisposing etiologic factors, as it was thought that their density and consequent low vitality predisposed them to exfoliation when attacked by inflammatory disease of the root. Harris* says, "It may also be produced by very hard teeth which, in consequence of their density, possess only a very low degree of vitality ; for cases of recession of the gums, in which a very slight inflammatory action exists, are frequently met with in individuals having teeth of this description. This can only be explained by supposing a want of congeni- ality between these organs and the more sensitive and highly vitalized parts with which they are in immediate contact." On making sections of these teeth, the enamel and dentin are found to be exceedingly hard and much more translucent than the average tooth. The pulp-chamber is usually considerably contracted, the pulp often show- * Harris's Dental Surgery. 544 OPERATIVE DENTISTEY. ing evidences of calcification, atrophy, and other senile changes. In the later stages of the disease the vitality of the pulp is often destroyed by the intense inflammation of the tissues of the apical space, the swelling pro- ducing pressure ujjon the pulp-vessels. An examination of the root reveals the fact that the pericementum is greatly inflamed or undergoing degenerative changes (Fig, 624), or has been destroyed to a greater or less extent according to the character and stage of the disease when the tooth was removed. Wherever tophi (con- cretions) have formed upon the root the j)ericementum will be missing, not only upon that portion of the root covered by the deposit but for a considerable area beyond ; this is a constant condition. It not infre- quently happens that the pericementum will be destroyed upon one side of the root from the cervix to the ajDex while it will be intact over the remaining surfaces ; or it may be destroyed upon all sides but one ; and, again, the process of destruction may encircle the tooth for an equal distance upon all sides. The latter condition is most often associated with the anterior teeth, and especially when the tooth has no immediate neighbors. As the disease progresses the teeth become more and more loosened in their alveoli, until finally they drop out or have to be extracted to relieve the intense soreness which is developed as a result of their mobility and frequent injuries due to their elongation and malocclusion. In cases of long standing a secondary form of deposit is often observed upon the roots of these teeth. The primary deposit is formed in thin scales just beneath the gum margin ; the secondary is formed beyond the primary deposit, upon the denuded cementum, in those locations which are constantly bathed in pus. The secondary deposits are so different in appearance that they cannot be mistaken for the primary deposit ; for, in- stead of being formed in thin scales with an even surface, they are formed either in tiny bead-like islands or in larger masses with bead-like projec- tions upon the surface, and very similar in appearance to the concretions formed upon bodies, either animal or mineral, that have been lodged in the tissues and bathed in pus for a considerable period of time. Such deposits are frequently seen upon the ajpical portion of the roots of teeth which have been the subject of long- continued chronic alveolar abscess. They are, therefore, not the primary cause of the disease, but the result of chronic inflammation and deposition of calcareous material from the inflammatory products. Symptoms and Diagnosis. — The first symptom of the disease in its early stages is usually inflammation of the margins of the gum, — marginal gingivitis,— which are turgid and reddened, the tips of the festoons often being of a purplish color. The extent of the swelling and discoloration will depend upon the severity of the inflammation and the diathesis of the individual. The gums bleed readily upon the least friction or rough usage. The margins of the gums are slightly everted, and the sulci or pockets formed between the margins of the gums and the cervices of the teeth are filled with food debris and thickened mucous secretions, or a thick, cheesy mass of material Fig. 624. — Inflamed peridental membrane from a case of pyorrhcea alveolaris. >' 50. PYOERHCEA ALVEOLARIS. 545 made up of these substances and epithelial scales, numerous forms of bac- teria, and calcic material. Later in the history of the case, if an instrument is passed beneath the margins of the gum, a scaly deposit of dark-green calculus will be found adherent to the cervix of the tooth. This may be upon one surface only, or it may encircle a larger portion or the whole of the cervix. Occasionally, however, cases will present in which the deposit seems to have occurred before the marginal gingivitis was developed, and that the deposit was the cause of the gingivitis. These cases may have their origin in cervical dejiosits, which later develop a chronic marginal gingivitis, as already described in the i^receding chapter, or it may be that the inflam- matory condition of the gum has subsided after the formation of a com- paratively smooth calculus. As the formation of the calculus progresses it encroaches upon the periosteum, causing inflammation and ulceration of this membrane. The constant presence of the i3yogenic bacteria in the mouth affords the means of septic infection, which attacks the tissues as soon as they can gain an entrance to them through an abraded surface or other break in their con- tinuity. As a result pus is formed, which may be pressed from beneath the margins of the gums. An examination of the margins of the alveolus with a fine probe will sometimes discover these edges eroded by caries, but more often they will not be found uncovered, the process of destruction seeming to be one of resorption rather than molecular disintegration by caries. In the former cases the odor of the pus is very ofl'ensive and dis- agreeably taints the breath. As the disease advances the pericementum and the alveolar process are progressively destroyed, and the gum gradually recedes as this process continues, until the tooth becomes very loose in its alveolus. The increased mobility, elongation, and the malocclusion incident to these conditions excite inflammatory action in the tissues beyond the field of the original disease, thus increasing the soreness and discomfort of the tooth. In some cases, at this stage of the disease, hy]3ersemia of the pulp may be developed, followed by embolism and death, or the inflammation and <]edema of the apical tissues may be so great as to cause strangulation of the vessels of the pulji at the apical foramen. As a result of the devitali- zation of the pulp and septic infection, the case may now be complicated with a septic apical pericementitis. The termination of the disease is in the exfoliation of the tooth. All inflammatory symptoms immediately subside upon the loss of the tooth, and the gums and alveolar border assume in a very short time a healthy appearance. Prognosis. — The prognosis is favorable, even in the later stage of the disease, provided the exciting causes can be removed and the constitutional predisposing causes, when they exist, corrected. Treatment. — In the treatment of ptyalogenic calcic pericementitis there are two main objects to be considered. The first is the removal of all sources of irritation, and the second is supporting the diseased teeth so as to secure surgical rest during the healing process. 35 546 OPERATIVE DENTISTRY. The removal of the sources of irritation comprehends all forms of local and constitutional irritants. The principal local irritants are the calcic deposits, food debris^ and septic bacteria. The removal of the deposits is a surgical procedure, and requires special instruments for its success. Instruments of an entirely different form are required in the removal of the subgingival salivary deposits from those employed in removing the ordi- nary forms of salivary calculus. The most important desiderata in the instruments used for the purpose of removing the deposits from the sides of the roots beneath the gums are, first, that they shall be so thin that they will pass readily into the pockets formed in the alveolar wall between the root of the tooth and the gum ; Fig. 625. After Burchard. second, so flexible or springy that when the flat side of the instrument is laid against the side of the root a lateral and downward pressure will cause the instrument to glide over its surface, removing any concretions that may be thereon, but not cutting into the cementum. These hard salivary concretions are most readily removed or scaled from the surface of the root by driving or pushing the instrument from the margin of the gum towards the apex of the tooth, keeping the flat side of the instrument always in contact with its surface. For this purpose chisel- shaped instruments only should be used. Fig. 625 shows the manner of PYOREHCEA ALVEOLARIS. 547 holding tlie iustrument, and Fig. 626 tlie application of the instrument ta the root of the tooth. Some operators, however, prefer instruments which can be used with a drawing motion, the cutting end of which is made like the hoe excavator, but with the blade much shorter. This of course makes the instrument bulky at its cutting end, and prevents Fig. 626. it from being carried as near to the apex of the root as is possible with the thin chisel-shaped instrument ; hence there is not the same certainty that the concretions are all removed in the farthest limits of the pockets as would be the case if the chisel-shaped instruments were em- ployed. The instruments best suited to this purpose are the Allport and the Gushing scalers (Figs. 627 and 628). The importance of the thorough removal of every particle of the deposit from beneath the gums cannot be over-estimated. Many failures to arrest the inflamma- tory symptoms in these cases can be traced to the fact that some small particle of adherent deposit has not been After Burchard. reached. The operation even under the most favorable circumstances presents many obstacles and difficulties, which can only be overcome by those opera- tors whose sense of touch has become so acute as to be almost the equal of vision. The six anterior teeth of both jaws present the most favorable conditions for the successful removal of such concretions. These difficul- ties, however, are greatly increased in the bicuspids and the molars by their Fig. 627. Allport's pyorrliiX'a alveolaris instruments. more inaccessible location, by their shape, and the number of their roots. The most difficult problem is the removal of the deposits fi'om the bifur- cations of the roots and from the surfaces of the roots which look towards each other. After the concretions have all been dislodged from their attachment to the root, the pockets should be injected with a drop or two of hydrogen dioxide (H^OJ by the use of the Dunn medicinal drop syringe (Fig. 629), in 548 OPERATIVE DENTISTRY. order to free the pockets from all calcareous debris ; after which they may- be treated by the application of aromatic sulphuric acid, lactic acid, trichloracetic acid, or a saturated solution of iodine crystals in beech- wood creosote. Various other remedies are employed for the treatment of the pockets, but the mention of these is sufficient to indicate their character. The after-treatment consists in the free use of antiseptic mouth-washes Fig. 628. Cushing's pyorrhoea alveolaris instruments. and painting the gums with equal parts of tincture of iodine and tincture of aconite every other day for a week or ten days. The writer has for many years been in the habit of employing an atomizer for applying the antiseptic lotions or mouth-washes in the treat- ment of these oral conditions. The patient is instructed to thoroughly brush the teeth after each meal, then to i)ass floss-silk between all of the teeth, and follow this cleansing process with the atomizer, using sufficient force to drive the antiseptic fluid through the interdental spaces. If by the end of a week the gums have not assumed their normal color, or there is still a discharge of pus from any pocket, the chances are that a small adherent scale of calculus still remains. This should be searched for and removed and the case treated as before. In all of those cases that are Fig. 629. Dunn medicinal drop syringe. complicated with systemic disorders which predispose to pericemental degenerative changes, attemj)ts should be made through the family medi- cal adviser to correct these conditions. Local treatment under such circumstances, although it may prove help- ful in relieving immediate suffering and placing the mouth and teeth in a more hygienic condition, will not prove curative until the constitutional dyscrasia is improved. PYORRHCEA ALVEOLA RIS. 549 Surgical Rest. — Teeth which have become much loosened by reason of the resorption of the alveoli must be given surgical rest if the healing process is to be successfully completed. This rest may be secured by sup- porting the teeth, either by ligatures of silk or linen attached to contiguous teeth, or by wire, either of gold or silver, or by splints made of gold or platinum and cemented to the teeth. These splints (Fig. 630) are most readily made by fitting thirty-four to thirty-six gauge bands to the individual teeth, taking an impression of them in situ, investing, and soldering the whole together. Fig. 631. Fig. 630. Splint prepared. (After Burchard.) Labial view of splint in po- sition. (After Burchard.) Fig. 632. Lingual view of swaged splint in position. (After Burchard. ) Fig. 631 shows this splint after it has been cemented in position. Or an impression may be taken of the teeth after they are supported with silk ligatures, and a splint swaged from gold or platinum and cemented in place, as shown in Fig. 632. OHAPTEE XXXIX. HiEMATOGENIC CALCIC PERICEMENTITIS. This form of pyorrhoea alveolaris is found most frequently in persons suffering from certain peculiar inherited or acquired constitutional condi- tions, — viz., rheumatic and gouty affections, or, in other words, the ar- thritic diathesis, and for this reason it has been termed by some writers gouty pericementitis. Magitot (1867), as stated in the preceding chapter, called attention to the fact that in his opinion persons of the gouty and rheumatic diathesis furnished the greatest number of cases of pyorrhoea alveolaris. Eeese (1886) i)ointed out most clearly the association of this disease with the gouty diathesis. The writer (1891) demonstrated the analogy between the gouty deposits and the degenerations of the fibrous tissues of the joints and certain pericemental degenerations, and suggested that certain deposits were found upon the roots of the teeth in locations which had no com- munication with the salivary secretions, and that these concretions were deposited from the elements of the blood, and were composed of the urates of lime and soda. Peirce (1892-94-95) has proved by careful experiments the truth of the above suggestions of the writer in relation to the location of these deposits and their composition. The demonstration of the fact by Dr. Peirce that the deposits found upon the roots of the teeth in these locations gave the murexid reaction proved conclusively that they contained biurates, the same as found in the gouty concretions in other j)ortions of the body. The establishment of this fact gave a great impetus to the study of the association of this disease with the gouty diathesis. The result of this study, however, in certain directions, through a misunderstanding of the premises laid down by the advocates of the theory, has been to throw doubt upon the correct- ness of their conclusions. The teeth that have been used in these studies by the opponents of this theory have admittedly been taken in great quantity, hap-hazard, from the scrap-box of the professional extractors, which made it impossible to obtain the history of a single case ; neither could there be any means of knowing whether the concretions used for the chemical analyses were deposited from the saliva in open pockets or from the elements of the blood in locations where the secretions of the mouth could not have come in contact with them. These are important distinctions, and if they are observed in future researches upon this subject they will give the same results as those obtained by Peirce and the other advocates of this theory. Predisposing Causes.— The predisposing causes of this form of pyorrhoea alveolaris (gouty pericementitis) are those conditions of the sys- tem which are designated as the gouty and rheumatic affections. Gouty pericementitis, however, is only a local manifestation of this general mor- 550 HEMATOGENIC CALCIC PEEICEMENTITIS. 551 bid state of the system, wliich is due either to imperfect metabolism (sub- oxidation and faulty elimination) or to an excessive formation of uric acid, resulting in the accumulation within the system of an abnormal amount of certain waste products termed the urates. Individuals who are thus affected are said to jDOSsess the uric acid or gouty diathesis. It must be remembered, however, that lead-poisoning resembles gout in giving rise to an excess of uric acid in the blood. Urates are always found in excess in the serum in instances of deficient oxidation, arthritis, and valvular diseases of the heart. They are also found in the urine, as, for instance, in a case of phthisis where an insuffi- cient amount of oxygen is absorbed, oxyhsemoglobin is deficient, and conse- quently many of the normal transformations of the body are completely or partially arrested. In such oases quantities of oxalate of lime will be found in the urine, the carbon of the food and of the waste material from the tissues is only j^artially oxidized, and that which should have been exhaled from the lungs as carbonic acid is excreted by the kidneys as oxalic acid. Again, in the condition of venous stasis arising from feeble action of the heart the blood stagnates in the veins, becomes loaded with poisons, is not carried to the lungs with due rapidity, and those nitrogenous parts of food and tissue which normally are converted into, and excreted as, urea appear in the urine as uric acid, free or combined. (Vaughn.) A persistent excess of uric acid in the urine is, therefore, always con- sidered as a significant symptom of an important systemic condition, due to an increase in tissue metabolism in some particular organ or group of organs. Heredity. — The gouty diathesis is usually inherited, and the active manifestations may be induced in such individuals by high living or by the deprivations of extreme poverty. Gairdner and Garrod state that in about ninety per cent, of all persons suffering from gout, the disease also existed in their forefathers. Peirce is of the opinion that in gouty pericementitis fully ninety per cent, manifest an hereditary tendency to the disorder. Gout diminishes the powers of resistance against disease and injuries, especially when the kidneys and the liver are affected. Many gouty indi- viduals, however, live to an advanced age. Diet. — The excessive use of foods containing large quantities of nuclein or saccharine substances, and the use of alcoholic beverages, particularly fermented liquors, are predisposing causes of gout, and also of this form of pyorrhoea alveolaris. Sex. — Sex does not seem to play a very im]3ortant part in the predis- position to pyorrhoea alveolaris in general. Men, however, are much more subject to gout than women, and as a natural consequence to gouty perice- mentitis. Age. — Gouty manifestations may appear at any period of life from infancy to old age. It is most common, however, after middle life. This is true also of gouty pericementitis, although cases have been recorded as occurring before the age of puberty, Magitot and Peirce both agree that this form of pyorrhoea is most 552 OPERATIVE DENTISTRY. frequent between the ages of thirty and fifty years, and that it rarely appears after the age of sixty. Occupation . — Sedentary occupations are important predisposing causes of gouty pericementitis, as they favor imperfect oxidation of the food, faulty metabolism, and retard the elimination of the waste products. Sys- tematic exercise in the open air tends largely to counteract these faults in the functions of the body. This morbid state of the system, known also as uricacidcemia or uricsemia, finds expression in a multitude of ailments and abnormal conditions of various tissues and organs, some of which are acute, others chronic, in their manifestations. Blood-Vessels. — Yarious functional and organic changes are found in the blood-vessels of gouty subjects, such as dilatation of the aorta, thick- ening of the walls of the arteries, loss of elasticity, atheroma, and even calcification. Phlebitis is a well-recognized gouty ailment, which may produce thrombosis, and by dislodgement of the clot cause sudden death by impaction in the heart, pulmonary artery, or lungs. Circulation. — The efi'ects of uricacidsemia upon the circulation, as pointed out by Haig, are to produce "contraction of the arterioles, and thus increase arterial tension." When these conditions affect the cerebral circulation they result in headaches, mental depression, fatigue, irrita- bility of temper, hysteria, vertigo, epilepsy, and convulsions. Asthma and chronic bronchitis are often the result of the effect of uric acid upon the pulmonary and bronchial circulation, and seem to explain the association so often noticed between these affections on the one hand, and gout and chronic Bright' s disease upon the other. Dyspepsia may undoubtedly be produced by the contraction of the arterioles of the stomach and intestines, thus inhibiting gastro-intestinal digestion and permitting putrefactive processes to take their jDlace, which would explain the association between dyspepsia and such affections as sick -headache, mental depression, fatigue, epilepsy, etc., or the relation- ship between dyspepsia and Eaynaud's disease or paroxysmal hsemo- globinuria. The liver is subject, also, to more or less congestion as a direct or in- direct result of circulatory changes produced by uric acid. Blood. — The blood itself is changed in a greater or less degree by the action of uric acid, both in its structure and its nutritive power. The presence of uric acid in the blood reduces the percentage of haemoglobin and the number of red corpuscles, thus iDroducing antemia. Haig was able to increase or diminish the amount of haemoglobin and the number of red corpuscles in his own blood from day to day by the administration of iron and uric acid respectively. The amount of uric acid in healthy blood is so small that it is with extreme difficulty that it can be detected. Garrod has demonstrated the fact, however, that in gout the blood is espe- cially rich in uric acid, and has found as high as 0.175 parts in 10,000, and that the blood is especially charged with it just prior to and during acute attacks, but that it is always present in chronic gout. Eoberts claims, however, that uric acid as such is never found in the HEMATOGENIC CALCIC PERICEMENTITIS. 553 blood or deposited in the tissues, but that as normally found in the blood it is in the form of a cxuadrurate, a compound of four equivalents of uric acid with one of soda or potash. This quadrurate is an exceedingly un- stable compound, and under especial conditions is liable to be decomposed into biurate and uric acid. The tophi of gout consist of the biurate, but this salt is almost insoluble in serum ; even at body temperature it is dissolved only in the proportion of 1 in 10,000. (Levison.) The tophi are formed by the transformation of the quadrurates found in the blood into biurate and uric acid, which gives rise to the deposition of the former compound in various tissues of the body, while the uric acid is eliminated by the kidneys. The tophus formed from this crystalline deposit of sodium biurate "acts passively and physically as a foreign body in the affected tissue or organ." (Luff.) Tunneclifife and Eosenheim* combat the claim of Eoberts of the ex- istence in the blood of uric acid in the form of quadrurates. They con- cede, however, the existence of two classes of uric acid salts, the neutral (CsH^NA)^ and the acid or biurate (C5H,N,03)HM. They conclude that there is no evidence of the existence of quadrurates, that the term should be abandoned, and that any theory concerning the pathology or treatment of gout built upon this assumption requires revision. They think the existence of two forms of uric acid (the tautomeric lactam and lactim forms) may explain the variation in the physic and physiologic be- havior of this acid and its salts. Molliere has demonstrated the fact that uric acid and the urates are antagonistic to the development of the i)yogenic micro-organisms. This exjjlains the reason why suppuration so seldom occurs about tophi, other than those located upon the roots of teeth. Duckworth found the red corpuscles diminished and the leucocytes somewhat increased in those cases already affected with chronic ne- phritis. The amount of urea found in the blood in all cases associated with granular kidney disease doubtless depends upon the degree of renal in- adequacy. Garrod frequently found oxalic acid in the blood of gouty subjects ; he believed its formation occurred principally in the paroxysmal stages, and that it was derived by oxidation from the uric acid. Ebstein discovered that xanthin and hypoxanthin were formed in the blood drawn from gouty subjects upon exposing it in a warm chamber, while minute quantities of uric acid disappeared. Secretions. — During attacks of uric acid headaches the urine and the salivary secretions are diminished, the mouth and tongue often being dry and parched ; in chronic gout this dry parched condition may last for months, but in acute gout, as soon as the excess of uric acid has been eliminated from the blood by the administration of appropriate remedies and the blood has assumed a normal alkalinity, the secretion of ui-ine and of the oral fluids becomes for a time relatively excessive. The saliva often * London Lancet, June 16, 1900. 554 OPERATIVE DE^•TISTRY. shows a decided acid reaction during attacks of acute gout, and usually gives a slight acid reaction in chronic gout. The amount of urea excreted in the urine, according to Garrod, is about three hundred and twenty grains per diem. Few analyses have been made of the excretion of urea in acute gout, but such as have been recorded show no material variation from the normal amount. The variation, how- ever, such as exists, bears no relation to the amount of uric acid excreted at the same time. (Garrod.) The excretion of urea is diminished just before an acute attack of gout. Haig gives the relation of urea to uric acid in the healthy adult as one to thirty-three, and says that in uric acid headache the excretion of urea was practically unchanged, while that of uric acid fluctuated greatly, particu- larly in relation to the headaches. Granville' s examinations of the urine of gouty subjects corroborate the records of Haig. The non-elimination of uric acid has been demonstrated by Garrod to be a constant and marked feature of paroxysmal gout. He found in several cases examined in reference to this point that the average amount was about five grains less than the normal,— 3.62 grains as against 8.569 grains. As a consequence of its non-elimination by the kidneys there is an in- creasing amount stored up in the blood or the tissues of the body. Haig is of the opinion that much of this may be stored in the liver and the spleen. The greatest amount of excretion in health occurs during the alkaline tide of digestion. (Eoberts. ) It is probable that the excretion of uric acid in gout, could it be watched from hour to hour, would be found to vary considerably. (Duckworth.) Sansone,* in analyzing one thousand grains of morning urine in a case of acute gout, found 0.830 grain of uric acid 5 in one of chronic gout, 0.120 grain ; and in a healthy person, 0.250 grain. Gouty individuals often suffer from gravel and calculosis ; oxaluria is not uncommon, while chronic cystitis and urethritis are occasionally ob- served in elderly persons suffering from gout. Kidneys. — The morbid changes which are found in the kidneys of gouty subjects present the ordinary signs of granular atrophy, and cannot be distinguished from it either by the symptoms or by an examination of its anatomical structure. The relationship between chronic Bright' s dis- ease and certain features of uricacidsemia is so constant that many observers have been led to believe that the disease was caused by imperfect meta- bolism of the albumins, and possibly as the result of the presence of an excess of uric acid in the system. Duckworth t is of the opinion that the gouty habit is alone the potent factor in a considerable proportion of all cases of interstitial nephritis. Ord and Greenfield,! in a large series of cases examined with the object of determining the i)resence or absence of renal disease in gouty subjects * Beale, Urine and Urinary Deposits, 2d edition, p. 162. t Treatise on Gout, p. 101. X Transactions of the International Medical Congress, 1881. HEMATOGENIC CALCIC PEEICEMENTITIS. 555 witli uratic deposits, found that in 66^66 -per cent, of the hospital cases of gouty affection of the metatarso- phalangeal articulation of the great toe there was a definite coexistence of contracted granular kidney, and that in the remaining 33.33 per cent, there were affections of the kidneys closely allied thereto. Out of ninety-six cases of renal disease, there were eight and possibly nine in which no uratic deposits were found in the joints. Of these, two were examples of extreme granular contraction, two of marked contracted granular, two of slightly granular, and one of mixed granular and tubular nephritis. Moore* examined forty-nine cases of chronic interstitial nephritis in males, and found uratic deposits in twenty-two. In another series of six- teen females, uratic deposits were i^resent in five cases. Continental European physicians generally hold the opinion that uratic deposits are constantly found in the contracted kidneys of gouty subjects, and that this condition is somewhat dependent upon the presence of such deposits. Duckworth's studies do not corroborate this opinion, as he rarely found such deposits in the kidneys of the gouty. Liver. — -Haig f is of the opinion that the hypereemia or congestion of the liver always present in diabetes is due to the same cause that produces this condition of the liver in gouty dyspepsia, — viz., the presence of an excess of uric acid in the blood. Ord X has pointed out the fact that general high arterial tension may cause an excess of blood in the liver, and thus produce diabetes ; while Haig § has shown that the contracted arterioles and arterial tension are in a direct ratio to the amount of uric acid circulating in the blood, and the so-called ' ' liver attacks' ' he looks upon as uric acid storms, almost if not quite identical with attacks of uric acid headaches. Diabetes seemingly holds a close relationship to gouty conditions, and must be dependent upon some error of metabolism for its existence. Both of these conditions present many similar symptoms. Latham || observed " that diabetic individuals often have an excess of uric acid in their urine and suffer from neuralgic pains in the joints and limbs." Anderson^ observed '^many clinical facts which seem to prove that gouty arthritis and diabetes mellitus are in certain cases merely trans- formed symptoms of the same diathesis ; not present at the same time, but one taking the place of the other. ' ' Garrod ** noticed this relationship, and says, ' ' In the course of practice I have seen several cases in , which gouty patients have become affected with saccharine diabetes or glycosuria. In one case of gout of twelve years' standing, in a gentleman sixty years of age, diabetes suddenly de- veloped, and for a period of over four years there were no more attacks * Loc. cit. t Uric Acid the Causation of Disease, p. 287. t British Medical Journal, 1889. § Uric Acid the Causation of Disease, p. 272. II Ibid. t British Medical Journal, 1886. ** Ophthalmic Eeview, 1889. 556 OPERATIVE DENTISTRY. of the gout. But when the diabetes was checked the gout very soon re- turned. ' ' Muscles. — Although no morbid changes have been observed in the muscular system in uricacidsemia, uric acid has often been found in these structures. Uricacidsemia produces, probably through depression of the nerve-cen- tres, a disinclination to muscular exercise during gouty attacks ; this re- sults in a deficient circulation in the muscles, and consequently in imper- fect elimination of the waste products. The tendons become involved in association with the joints and uratic deposits are formed in them. The muscles often become the seat of neuralgic pains, which come and go with other gouty symptoms. Nervous System. — So far no morbid changes have been discovered in the anatomical structure of the nerves of gouty subjects except those due to cachexia in cases of long standing. Uratic deposits are rarely found in the nerve-tissues or their investments. Cornil discovered sodium urate in cerebro-spinal fluid, and uratic deposits have been detected in a few in- stances in the cerebral meninges. Albert and Ollivier also found such deposits on the spinal meninges. There are strong clinical reasons for believing that uricacidsemia may in- duce neuritis in almost any nerve-trunk, with motor, sensory, and vaso- motor symptoms. (Duckworth.) Neuralgia is a common affection in gouty individuals. Sciatica and general myalgia are not infrequently associated with other gouty symptoms, and the writer has seen several cases of trifacial neuralgia which were undoubtedly due to gout. Skin. — The circulation and the nutrition of the skin are often markedly affected by the i)i"esence of an excess of uric acid in the system, which are manifested during uric acid headaches in a pale, cold condition of the sur- face of the skin, and in certain eruptive diseases, particularly those of an ulcerative character. Among the diseases allied to gout may be mentioned erythema, eczema, urticaria, psoriasis, prurigo, and acne. (Sarjou.) Gold- ing-Bird discovered uric acid in the contents of the vesicles of gouty eczema, and Begbie found it in the bullse of pemphigus. Ulceration of the skin and suppuration often accompany the exfolia- tion of the tophi located about the joints. Periosteum and Bone. — Uratic deposits frequently occur in the peri- osteum, resulting in inflammation and sometimes in exfoliation or extru- sion of the deposit. On the other hand, inflammatory symptoms are often present in and about the epiphyses of the long bones, particularly of the legs, feet, and hands, which result in the formation of nodes or of a true exostosis. The thickening of the edges of the alveolar processes so often seen associated with gingivitis is usually the result of chronic irritation or inflammation of the periosteum of these parts due to the gouty diathesis. Nails. — These tissues are dermal appendages, and are therefore more or less profoundly affected by all diseases which have a predilection for dermal structures. In gouty individuals the nails are observed to be coarse, fibrous, and brittle, striated, fluted, and lined vertically. After an acute attack of gout depressions or white spots or lines are H./EMATOGENIC CALCIC PERICEMENTITIS. 557 observed, forming crescent-like curves, which points to faulty nutrition, and, inasmuch as the nail requires six months in which to complete its de- velopment, these defects, by their position, would indicate the date at which the illness occurred, just as faults of nutrition are recorded upon the enamel of the permanent teeth, and indicate by their location the age of the individual when the illness occurred. Hair. — Senile changes occur earlier in certain tissues than in others. These tendencies may be acquired as the result of disease or of debauchery, or they may be inherited as a family peculiarity, or an evidence of de- generacy. This tendency to early senile change is particularly noticed in refer- ence to the hair. In some individuals the hair turns gray at or before the thirtieth year, while in others distinct baldness may occur at an equally early age. These conditions are often noticed to be associated with the gouty diathesis, and in some instances are no doubt dependent upon uricacidsemia as a primary factor in its causation. " The hardened tophace- ous matter sometimes found in the sebaceous glands of gouty subjects is composed largely of urates. About fifty per cent, of it is sodium and cal- cium salts of uric acid, about ten per cent, sodium chloride, and the re- mainder calcium phosphate and animal matter." (Duckworth.) Teeth. — The character of the teeth in gouty subjects is remarkable in that, as a rule, they are well formed, finely developed, having strong, hard enamel, which is inclined to a yellowish color ; they have strong roots which are firmly set in their alveoli, and are comparatively immune to caries. After middle life they are inclined to show considerable wear upon the morsal surfaces. This has been thought to be due to the habit of grinding the teeth which is so common with rheumatic and gouty indi- viduals. This habit is doubtless formed as a result of irritation and hyper- semia of the pericementum so constantly present in chronic gout. Neu- ralgic pains are also frequently present, and come and go with other gouty symptoms. The teeth, like the hair, often show evidences of early senile changes. The pericementum and the alveolar processes atrophy and are resorbed, while the gums gradually recede as the former conditions pro- gress until the teeth become loose and fall out. These changes often begin before middle life is reached, and when these tendencies are associated with a gouty diathesis the destructive process becomes most marked and rapid in its progress. Exciting Causes. — The immediate exciting cause of gouty pericemen- titis is undoubtedly the presence of uratic deposits in the pericemental membrane. This morbific material plays the part of a foreign body, and causes mechanical irritation and death of the surrounding cellular ele- ments, — necrobiosis, — which favors the further deposition of the urates. The inflammatory process does not always progress to the suppurative stage, as infection with the pyogenic cocci is necessary for the establish- ment of a septic inflammation. Impaired nutrition of the pericementum with its consequent lowered vitality is also an important factor in the establishment of the disease. These conditions are to be found as a result of severe mechanical strain 558 OPERATIVE DENTISTRY. from over-exercise of the teeth, — misuse^ — as in malocclusion and the loss of the teeth, which places the strain of mastication upon a few remaining teeth ; in insufficient exercise of the teeth — disuse — from various causes, as, for instance, loss of occlusion, the constant use of soft, pulpy foods which require little mastication to comminute their substance ; overcrowd- ing of the dental arch ; traumatic injuries consequent upon wedging, mal- leting, changing the position of certain teeth in the process of regulating, and other similar procedures. The unskilful or immoderate use of the tooth-pick, fioss-silk, and the toothbrusli may occasionally induce con- ditions of irritation which impair the nutrition of the pericemental membrane. Varieties. — ^In gouty pericementitis two forms of inflammation may be observed, — one which produces a new growth of cementum, or hyper- cementosis, and another which results in a deposition of calcic material combined with sodium biurates from the elements of the blood. The former variety has already been described in the preceding chapter on ^'Pericementitis." The latter variety is that condition which has been classed by Peirce, Darby, Burchard, Jack, and others as gouty pericemen- titis, and which the writer has described as a local manifestation of the gouty diathesis, in which tophi are formed within the pericementum, and upon the surface of the cementum in closed pockets, and in various loca- tions more or less remote from the cervix and at the apex. '■ ' These tophi are composed of sodium and calcium biurates, free uric acid^ and calcium phosphate, as has been demonstrated by careful analysis." (Peirce.) The manner in which these tophi are formed within the pericementum is as yet an unsolved proposition, although various theories have been advanced in explanation of the process. Pathology and Morbid Anatomy. — Gouty deposits are met with only in tissues which have a scanty vascular supply, or in which the circulation is more or less sluggish. Tophi are most frequently found in the tissues which surround the joints, like the cartilages, aponeuroses, and perios- teum. The small joints are most often affected. The relation of the teeth with the alveolar process is that of gomphosis, a species of joint termed the dento-alveolar articulation, and the tissue which intervenes between the cementum and the bone is the pericementum, a dense fibrous structure having a scanty vascidar supply as compared with the somewhat analogous structure, the periosteum. Under certain conditions exostosis and nodular formations occur upon the surfaces of the bones as a result of the irritation of the periosteum from the presence of the gouty poison in the blood and its deposition within the tissues. The same condition has already been re- ferred to as occurring uj)on the roots of the teeth from the same cause. There would seem to be, therefore, no good reason for objecting to the con- clusion which has been reached by so many able observers, — viz., that the deposits formed upon the roots of the teeth primarily in the pericementum and in closed pockets which could not have been at any time in commu- nication with the oral cavity, must have been deposited from the blood ; and, inasmuch as tophi are also found in the jjeriosteum surrounding a joint, the inference is fair that similar tophi may be formed in the peri- HEMATOGENIC CALCIC PERICEMENTITIS. 559 cementum surrouiiding the root of the tooth and forming the "joint" with the alveolar process. Formation of Deposits. — In relation to the manner or modus operandi of the formation of these tophi, Mordhorst * says, ' '■ The granular urate is always the precursor of the crystalline form, and in the bodyflnids the uric acid circulates in the form of invisible granules of sodium urate. Gouty deposits are only met with in non- vascular tissues, and as acids and acid salts diffuse more rapidly and readily than alkalies and alkaline salts, we must suppose that the alkalinity of the non-vascular tissues is less than that of ,the blood. Hence if a transudate almost saturated with urate enters such a less alkaline tissue the solution becomes supersaturated and granular urate is precipitated in the tissue, the precipitation being favored by such additional factors as lowered temperature or increased concentration of the fluids of the tissue. The precipitation of the granular urate in the spaces of the interstitial tissue and in the lymph-channels is the cause of the various phenomena of gout. In the course of time the urate deposited becomes converted into acicular crystals of sodium biurate, or under favorable conditions may be redissolved and disappear, and with them disappear the lesions to which they gave rise." If this theory is correct it explains why constitutional treatment, which aims to redissolve and eliminate the biurates, often mitigates the severity and sometimes cures certain cases of gouty pericementitis. Ebstein t believed that in gout uric acid is formed in excess in the body, and that hyper- j)roduction also takes place in regions which ordinarily do not produce uric acid, as, for example, the bone-marrow, the carti- lages, etc. When the blood and the lymph are overcharged with uric acid it may act as a chemic poison, causing morbid processes in the tissues and giving rise even to necrobiotic changes ; when these have reached a cer- tain degree the biurate is deposited in the necrotic parts of the structures, whereas such deposition is never found elsewhere. Klemperer]: is of the opinion that "the phenomena of gout cannot be explained by a mere crystallization of urates from the blood, or by the production of necrotic changes due to its ]3resence in the circulation, seeing that in other conditions in which uric acid is present in excess in the blood, such as leucocythsemia and chronic nephritis, neither uratic deposits nor necrosis of cartilage are met with. Some unknown sub- stances produce in gouty persons inflammation and necrotic changes in various tissues, and the necrosed tissues possess the power of attracting to themselves the excess of uric acid in the blood, while the chemic affinity of the necrosed parts for uric acid prevents the deposits from being redissolved by the blood. The writer has called attention to the fact § that rheumatic and gouty * Zeits. f. klin. Med., p. 65, 1897, from Sarjou. t Nature u. Behandlung d. Greht., from Sarjou. X Deutsche med. Woch., xxi. p. 655, 1895, from Sarjou. § The Eheumatic and Gouty Diathesis, as manifested in the Peridental Membrane^ Journal of the American Medical Association, 1891. 560 OPEEATIVE DENTISTRY. conditions are often observed in the form of inflammation of the peridental membrane as a primary symptom of an approaching acute attack of articular rheumatism or of gout, and that many times this condition is the only local expression of the diathesis. Tliis fact has been overlooked by the general practitionei", and consequently no mention is made of this symptom of gout and rheumatism in works upon these diseases. The fact of the acute susceptibility of the peridental membrane to the presence of the materies morM of these diseases is a clinical fact which has only been recognized by dental specialists during the last few years. In- flammation of tBe pericementum as a manifestation of the gouty diathesis is proved by the relief obtained from the exhibition of therapeutic reme- dies which eliminate the uric acid from the system. In the preceding x^ages it has been shown upon the best authority that gout, which is primarily a joint affection, may also exist in certain dis- orders of the blood-vessels, the circulation, the blood, tlie secretions, the muscles, the kidneys, the liver, the stomach, the nervous system, the skin, the periosteum, the bones, the hair, the nails, etc. The effects upon these tissues and organs of the presence in the system of an excess of uric acid are peculiar to each particular kind of tissue and to the function of the organ, the variety of the manifestations being as numerous as the tissues and organs affected. In the periosteum, the character of whose tissue most nearly approaches that of the j)ericementum, these manifestations are, as already noticed, of two forms, one chronic in character, which results in the formation of nodes and exostoses, and the other acute, in which uratic deposits are present. These deposits may be in the form of defined concretions, when they are readily detected ; but, as pointed out by Mordhorst, they may be deposited in the form of invisible granules and later converted into acicular crystals of sodium urate, which still might be so small as to escape detection. The deposits which are formed uj)on the roots of the teeth in gouty pericementitis are thin, greenish-colored, hard scales composed of urates of sodium, calcium, etc., which are very adherent and often require con- siderable force to dislodge them. These concretions may be located upon any aspect of the root, but most frequently upon the lingual and approxi- mal surfaces towards the apex. Uratic deposits upon the roots of the teeth are, however, not so common as might be supposed from the literature upon the subject. All calcic de- posits of dark color found upon the roots of the teeth are by no means evi- dence of a gouty condition of the system. Such deposits which have been exposed to the fluids of the mouth and constantly bathed with pus will always be dark colored and have the appearance of being formed from tiny globular masses, a condition usually observed in the concretions which have accumulated upon the surfaces of foreign bodies, bullets, frag- ments of metal, etc., which have been buried in the tissues and bathed in pus for a considerable period. This same form of deposit is found upon the roots of devitalized teeth which penetrate the floor of the antrum of Highmore, and which, by inducing septic infection of this sinus through the agency of a putrefying pulp, has caused empyema. H:^MATOGENIC CALCIC PERICEMENTITIS. 561 Eoots of teeth, wliicli have been forced into the antrum in an effort to extract them, teeth which have erupted into this sinus, and foreign bodies which have been introduced by traumatism invariably induce suppuration. These bodies after a time become covered with concretions which have a dark-green color and a roughened surface like that just described. The variety of deposit found upon foreign bodies and the roots of teeth seems to be peculiarly and almost invariably the result of the supiDurative process, the concretion being calcic material, and rarely responding to the murexide test for uric acid. Concretions which are identically the same are frequently found upon the "roots of the teeth in pyorrhoea alveolaris in its later stages, when the roots of the teeth have been bathed in pus and the oral secretions for months, and the deposit constantly accumulating until the tooth is ex- foliated. Cases of this character when tested for uric acid usually give negative results, and yet it is largely this class of cases which have been selected for chemical analysis with the view of discrediting the theory that uric acid plays an important part in producing that peculiar form of pericementitis accompanied with suppuration which has been designated "gouty pericementitis." The deposits in true gouty pericementitis are formed in tiny islands of irregular outline, and in the form of thin scales with smooth surface, dark- green in color, and very firmly adherent to the surface of the cementum. These deposits are doubtless formed in the pericementum through the agency of some unknown substances, as suggested by Klemperer, which in gouty persons produce inflammation and necrobiotic changes, while the necrosed tissues possess the power of attracting to themselves the excess of uric acid in the blood. The chemic affinity of the necrosed tissues for uric acid also prevents them from being redissolved by the blood when it has assumed its normal alkalinity. The i^resence of these deposits uJDon the root of the tooth produces symptoms of irritation of the pericemental membrane. Sooner or later this develops inflammation and the formation of an abscess at the location occupied by the deposit, which may point directly through the gum or burrow along the side of the root and discharge at the cervix. These abscess pockets, as the writer pointed out some years ago, have no com- munication with the oral secretions until pointing takes place, and this fact has been demonstrated over and over again by the most thorough and painstaking examinations. The infection, therefore, which induced the suppurative process could not have occurred from the mouth, — unless the suggestion of Black * is correct, that ' ' infection may possibly take place through the glandular structures which he has discovered in the pericemen- tum," — but most likely it has come through the avenue of the circulation. For this reason the writer is of the opinion that the gouty deposits in the pericemental membrane do not immediately cause suppuration, and that the presence of the pyogenic cocci in the blood-current are necessary to establish this process. * Dental Review, vol. xi. p. 258. 36 562 OPEEATILE DENTISTRY. The character of the inflammation which is primarily established in these cases is always acute, the abscess usually pointing in from twenty- four to forty-eight hours. The presence of the concretion is readily demon- strated by laying the abscess open, excavating the pus, and packing the cavity with a tiny strip of gauze or a pledget of cotton for a few hours or overnight. On removing the dressing and irrigating the cavity the deposit is brought to view. This would seem to settle the question of the deposit being the cause of the irritation^ and that it was not formed as a result of the suppurative process, as this is acute and of such brief duration that a con- cretion of this character could not be formed in so short a time. Neither is it possible for the concretion to have been deposited from the oral secre- tions, for no communication existed between them until the abscess pointed. Symptoms and Diagnosis. — The first symptom of gouty perice- mentitis is soreness and elongation of the tooth, followed in a few hours in the suppurative variety by swelling of the gum either upon the buccal or lingual aspect at locations varying from midway of the length of the root to the apical region. The swelling is accompanied by considerable pain of a throbbing character. At the end of twenty-four to forty-eight hours fluctuation may be felt, and upon opening the swelling pus escapes. The early stages of the disease so closely simulate septic apical pericementitis and dento-alveolar abscess that it may readily be mistaken for these affec- tions. It may, however, be differentiated from them (1) by the fact that the teeth affected are usually vital ; (2) that the swelling is generally con- fined to the gum over the affected tooth, and rarely extends to the overlying soft tissues ; (3) the character of the pain is not so severe nor the duration of the attack so prolonged ; (4) the abscess is limited to a comparatively small area, and there is usually no communication between the abscess- cavity and the apical space. The peculiarity of this variety of abscess is that it is formed about a tophus located upon the surface of the cementum, and that until the abscess ruptures there is no communication between it and the cavity of the mouth. Prognosis. — The i^rognosis will depend largely upon the success of the constitutional treatment in eliminating the uric acid from the system and preventing its excessive formation afterwards, and also in the thorough- ness with which the irritating concretions are removed from the roots of the teeth. Marked and almost immediate relief is frequently obtained by vigorous general therapeutic measures addressed to the elimination of the quadrurates. A favorable prognosis cannot be hoped for, however, by constitutional treatment alone. Local treatment must be instituted for the removal of the concretions, and this must be etfectually done if the sup purative process is to be controlled. Because one or more teeth have been attacked by this disease it does not follow that all of the teeth, or even any others, will be so affected. The disease usually manifests itself in those teeth which have suffered in- jury of some form to the i)ericementum whereby its resistive power has been weakened. Constitutional measures which have for their object the control of the disease by restricted diet and j)roper exercise must be rigidly carried out if the desired object is to be gained. Half-way meas- HEMATOGENIC CALCIC PERICEMENTITIS. 563 ures are worse tlian useless. The prognosis will be unfavorable if the irri- htlT ""tT"^'"' ""'' "'* '"^^^"^ ^" ^^" constitutional dyscrasia com- bated. Such cases are marked by chronic inflammation and suppuration loosening and extrusion of the tooth, which may also turn upon its aS Fig. 633. Fig. 634. After Dr. George S. Allan. After Dr. George S. Allan. and form a wide separation from its neighbor on one side Dr Georo-e S Allan presented to the ^w Jersey State Dental Society casts taken from the mouth of a gentlemen which represent these features of the disease. Fig. 633 represents the denture before the disease appeared j Fig. 635. After Dr. George S. Allan. Fig 634 Shows the condition one year later; Fig. 635 exhibits the case with the tooth permanently elongated after treatment, while Fig. 636 shows the appearance of the denture after the tooth had been shortened by grind- ing to match its fellow. .y s "^ Fig. 636. After Dr. George S. Allan. Treatment— The treatment of gouty pericementitis to be effective must be applied to both the local and the constitutional conditions Local Treatment.— The treatment of the local conditions compre- hends the removal of the deposits, the control and suppression of the in- flammatory symptoms, the stimulation of the healing process, the institu- tion of thorough and vigilant oral hygienic measures, and the support of 564 OPEEATIVE DENTISTRY. the teeth to obtain surgical rest, as already described under the head of ptyalogenic calcic pericementitis. The tophus may be readily discovered by opening the abscess by means of a curved incision, lifting the flap, and packing the cavity for a few hours with gauze or cotton. After removing the concretion the cavity should be irrigated with an antiseptic solution, the flap brought into apposition and retained until healed by a couple of sterilized horse-hair sutures. Fig. 637. ^-pj^^ ^3^^^ /\i_ Constitutional Treatment. — The constitutional iilllllr i y ^ treatment of gouty pericementitis is that which should I IF j p\!4 jilii iliii _B be prescribed for gout in general. Any regime which (^^mi " "^^ J!l \\l T ^ ^"^^ prevent the accumulation of an excess of uric / IP^ ^ ^^^^ ^^ ^^ blood or effect its elimination when formed I lili|- S II ^^ produce beneficial results in gouty pericementitis. ^~n r— ""^^ Preventive Treatment. — Prophylactic treatment Gum turned aside, show- iu gouty Conditions of the system should be instituted ing underlying condition in ^^. euough iu thosc individuals who have inherited a ease of pyorrlioea alveo- '' ^ laris. A, cervix of tooth ; the prcdisposition to Ward off a first attack ; or after B, thickened and degener- ^j^^ development of the discasc to prevent or, at least, ated pericementum ; C, al- ' veoiar process thinned and to retard the recurrence of any future attack. This irregularly absorbed ; D, j^ay be accomplished by a restricted diet and hy proper amount of out-door exercise. Gouty individuals and those with the inherited tendency to the affec- tion should eschew all food which contains much nuclein, as this substance tends to increase the percentage of uric acid in the blood. Sweetbreads, liver, brains, kidneys, and meat extracts all contain large quantities of nuclein, hence are contraindicated in gouty subjects. Eggs are admissi- ble, as they contain no nuclein, but instead paranuclein, which during the metabolism of digestion and assimilation is not converted into uric acid. Meat and fish contain proteids, but as this substance is not decomposed to form uric acid, a moderate amount of these foods may be taken. Sarjou places the daily allowance at two hundred grammes, a trifle over seven ounces. A larger quantity he thinks would overtax digestion and the eliminative powers of the kidneys. Haig* says, "The uric acid taken in the food constitutes the bulk of the uric acid eliminated. The avoidance of animal food containing xan- thin compounds or uric acid, and also tea, coffee, and cocoa, whose alka- loids are similar xanthin compounds, will gradually eliminate any excess of uric acid in the system." Kolisch t would eliminate every influence which might tend to irritate or injure the kidneys, and he regards alcohol and foods which might in- crease the amount of the irritating alloxins as especially harmful in this direction. Among the latter he classes flesh rich in cellular elements, while muscle, particularly if it has been boiled, he regards as permissible. * British Medical Journal, March, 1897. t Wiener klin. Woch., No. 45, 1895. H-^MATOGENIC CALCIC PERICEMENTITIS. 565 Milk and eggs he thinks are free from objection, as the nucleins (para- nuclein) which they contain do not form alloxins. The carbohydrates and fats he thinks are allowable, and vegetables, — salads and greens, — except- ing asparagus, are useful. ]!«3"othnagel * recommends as a diet for gouty patients plenty of fresh vegetables, fruits, and starchy food, small quantities of meat, and the exclusion of sugars. Laquerf recommends fatty milk, according to Gartner's formula, as a suitable diet for all cases of gout. He thinks the administration of milk increases the excretion of xanthin bases and reduces that of uric acid. An increased quantity of water in the diet increases the alloxin bodies (uric acid and xanthin bases) in healthy persons. Wood X thinks that milk probably suits the largest number of gouty patients, but believes there is no diet for gout. The diet must be adapted to the individual case, l^evertheless, in a large majority of cases, sugar and starches must be cut off. But in spare gouty subjects a farninaceous diet may be essential. The ingestion of large quantities, three to four pints or more, of fluids, such as milk and pure water, especially skim-milk and buttermilk, and dis- tilled water or lithia water, is to be recommended, to favor the free action of the kidneys and to stimulate the elimination of the waste products. Alkaline waters were at one time very widely recommended in gout and rheumatism, but experience has shown that when the waters contain soda in any appreciable amount their ingestion is liable to accelerate the deposition of the biurate and thus provoke an attack of gout. (Sarjou.) Alcohol as a beverage in whatever form should be eschewed by gouty subjects, as numerous observations have proved its pernicious effects. Alcohol increases the formation of uric acid and favors the deposition of the urates. The pernicious effect of alcoholic beverages in these cases is thought to be due to the incomplete process of fermentation by which they are produced. The light wines are the least injurious, and Bordeaux, Mosel, and Rhein wines may be taken in small quantities ; but the stronger wines, like sherry, port, and champagne, and ale, porter, and stout, should never form a part of the diet of a gouty individual. In certain persons a glass of any of these beverages would be sufficient to provoke an attack of acute gout of the great toe, a gouty sick headache, or an attack of iDyorrhcea alveolaris. Exercise. — Exercise to be beneficial as a prophylactic measure in gouty conditions should be regular, and of such a vigorous nature as to . bring a healthy glow to the surface of the body and stimulate the emunc- tory organs. Such exercise should be taken out of doors, and may consist of walking, riding, cycling, or playing tennis, golf, cricket, base-ball, etc. "Over-exercise is harmful on account of the tendency to increase the alloxin productions. ' ' (Kloisch. ) * Internat. klin. Rundschau, February 14, 1892. t Berliner klin. Woch. , September 7, 1896. I New York Medical Eecord, July 10, 1897. 566 OPERATIVE DENTISTEY. Treatment of Acute Attacks. — In the systemic treatment of acute attacks of gout, it is obvious that the treatment should be directed towards the elimination of the excess of uric acid and its compounds which are present in the blood and tissues of the body. Until quite recently alkalies and alkaline combinations have been the most generally favored remedies in the treatment of gouty conditions. Of these combinations the most generally employed were the carbonates and phosphates of sodium and potassium and the carbonate of lithium. The use of these remedies was based upon the supposition of an acid condition, or rather a lessened alkalinity of the blood, and that by the ingestion of alkaline remedies the alkalinity of the blood would be increased and its power to dissolve uric acid and prevent the deposition of the biurate greatly augmented. The experiments of Roberts have proved these sup- positions to have been based upon false premises. In the first place, there is no such thing as an abnormal acidity of the blood in gout, and, second, "the addition of the carbonates and phosphates of alkalines to blood-serum impregnated with uric acid did not retard the precipitation of biurate ; the alkalines are consequently without power to prevent the formation of uratic deposits, and the salts of soda may even prove directly pernicious when taken in large doses." (Levison.) The alkaline lithiu mcompounds — the citrate and carbonate — have been quite extensively employed in the milder cases of gout, the subacute and chronic forms, and with seeming good results. Tartarlithine, lithium bitartrate, and alkalithia, prepared in five-grain tablets, are very conve- nient for use. They may be prescribed, one tablet dissolved in a glass of hot water three or four times per diem. Of the mineral springs the Saratoga, Vichy, Buffalo lithia, Carlsbad, and Apollinaris are probably the best. Among the prepared waters the ozonated lithia is the best. Waters of this character to be of real benefit should be drunk in large quantities, so as to increase the excretion of urine to from three to five pints daily. Among the other remedies which are employed to eliminate the waste products and check the excessive formation of uric acid are colchicum, guaiacum, calomel, and the salicylate of sodium. In order to check the excessive production of uric acid it is necessary to promote liver-metabolism and relieve the congested state of the portal system. These results may be secured by regulating the diet and daily regimen and the administration of colchicum. This drug is usually ad- ministered as wine of colchicum, in doses of twenty-five minims three times per diem. Or it may be combined with three to five minims of the tincture of aconite. Colchicum must be used with circumspection, as it is liable, if administered in large doses, or its use long continued, to produce nausea and diarrhoea. For these reasons the use of the drug should not be continued in any case for more than four to six days. Colchicum not only relieves the torpid condition of the liver and the portal system, but it relieves the severe pain of gout better than any other drug. Its mode of action, however, is obscure. Guaiacum also stimulates hepatic metabolism and checks excessi^•e uric H-^MATOGENIC CALCIC PERICEMENTITIS. 567 acid formation. It also stimulates the kidneys, and assists them to elimi- nate the uric acid formed in them, and prevents its absorption by the blood. This drug- is usually prescribed in the form of the tincture gaaiaci ; dose, one to two fluidrachms three times per diem, administered preferably in milk. Calomel is administered for the same purpose, but the best results are obtained by giving it in divided doses until it freely moves the bowels. ' ' To promote the elimination of the quadrurates formed in the kidneys and so to prevent their absorption into the blood is to strike at the primary evil in the causation of gout. To promote this, diuresis should be increased and the acidity of the urine diminished. Citrate of potassium is a good diuretic, which not only increases the solubility of the quadrurates, but also diminishes the acidity of the urine, and should be continued until moderate alkalinity of the urine is produced." (Luff.) Salicylate of sodium and the salicylate of lithium have been more or less extensively employed in the treatment of acute gout, but they are greatly inferior to colchicum. These remedies find their most useful field in those cases in which colchicum is not well borne by the stomach. They have the power of clearing the system of uric acid, but they do not reach the primary cause of the disease, which lies in a faulty metabolism. Various basic organic compounds, such as piperazin, lycetol, and lysidin, have been recently introduced as specifics for gout and uric acid gravel. But the opinions as to their value are so conflicting that they can- not at present be recommended. In this study of gouty pericementitis the writer has endeavored to present the subject in such a manner that the student may get a somewhat broad view of that condition of the general system known as ' ' uricaci- dsemia," and its manifestations in the various tissues of the body other than those which surround the root of the tooth, with the hope that the presentation will assist in clearing up some of the misconceptions of those who oppose the theory and of some of its over-zealous advocates who have claimed too much for it. CHAPTEE XL. PHAGEDENIC PERICEMENTITIS. Definition. — Phagedena (from the Greek (payeZv^ to eat) is a spreading and destructive ulceration, often of an obstinate character, which rapidly destroys or disintegrates the soft parts. Dr. Black first introduced the use of the term ' ^ phagedenic pericemen- titis" to describe a peculiar form of pyorrhoea alveolaris whose most char- acteristic symptom was a progressive ulceration and destruction of the pericementum and alveolar process. Phagedenic pericementitis may be described as an inflammation of the peridental membrane accompanied with a progressive ulceration of a phagedenic or spreading ty^De, showing a marked inclination to extend or progress most rapidly in a direction corresponding to the long axis of the tooth, and beginning apparently at the gingival border of the gum in a slight gingivitis, but really in the marginal attachment of the membrane. The disease causes destruction of the pericemental membrane and of the alveolar process immediately overlying the inflamed area, but in the early stages leaves the gum intact. This process of disintegration is accom- panied with a slight reddening and congestion of the overlying gum, the formation of deep narrow pockets, the deposition in some cases of calcic material, and the discharge of a variable quantity of pus which makes Its appearance on pressure being applied over the inflamed area. The disease may be either acute or chronic in its manifestations. Phagedenic pericementitis is entirely distinct from hsematogenic calcic pericementitis, in that the inflammation is not dependent upon the forma- tion of uratic deposits, and that the destructive process always begins at the marginal attachment of the membrane and progresses towards the apex of the root, spreading less rapidly in lateral directions, and destroy- ing the xDcricementum and alveolar tissue simultaneously by a process of molecular necrosis, while it presents clinic features which indicate it to be an infectious disease. In hsematogenic calcic pericementitis the inflamma- tory process is dependent upon the formation of uratic deposits within the peridental membrane ; these concretions are deposited in locations remote from the marginal border of the membrane ; they form distinct abscesses, which -are confined at first to these locations, and have no connection with the oral cavity until the abscess ruptures ; neither does the affection show any characteristics of an infectious disease. In other respects they have many features in common. Causes. — In regard to the nature and etiology of phagedenic perice- mentitis very little is positively known. Certain general and local con- ditions seem, however, to have a bearing upon the disease, either as causa- tive or resultant factors. It is true that some of these conditions seem to act as predisposing and others as exciting causes of the affection. They 568 PHAGEDENIC PERICEMENTITIS. 569 may therefore be divided into predisposing and exciting causes, the former being largely of constitutional origin, the latter principally local. Predisposing Causes. — Certain systemic conditions, by a seeming predilection, find expression in various inflammatory manifestations in the peridental membrane, some of which are constructive in their character, others destructive ; as, for instance, certain gouty conditions cause through irritation of the pericementum and stimulation of the cementoblasts the formation of new cement-tissue (hypercementosis), or in scurvy, which causes through intense inflammation of the pericementum destruction of this membrane and exfoliation of the teeth. Phagedenic pericementitis generally arises under the influence of cer- tain diseases or unfavorable conditions of health, — conditions which are productive of general debility and degenerations of special tissues like the pericementum, — and it is manifested either as a complication or as a sequel of these conditions and diseases. Among the more common general conditions and diseases which are sometimes complicated with phagedenic pericementitis or are followed by it are hereditary tendencies, anaemia, locomotor ataxia, diabetes mellitus, albuminuria, osteitis deformans, scurvy, certain nervous diseases, typhoid fever, tropical fever, certain infectious diseases, particularly the exanthematic fevers, influenza., smallpox, syph- ilis, gonorrhoea, and tuberculosis, pyaemia, nephritis, pregnancy, sterility, and the selective action of those drugs which produce mercurialism, plum- bism, iodism, and alcoholism. The pericementitis of scurvy, mercurialism, plumbism, and iodism in their aggravated forms are always of the phagedenic type. It should be remembered, however, that the teeth are dermal append- ages, and are therefore more liable on this account to be affected by such diseases and drug impressions as are peculiarly manifested in or have a predilection for epiblastic and hypoblastic tissues. The teeth are also in a certain sense transitory organs, and are therefore prone to take on senile and other degenerative changes, resulting in atrophy of the pericementum and alveolar structures and loss of the teeth. For this reason some authorities have looked upon phagedenic pericementitis as a ^'premature senile degeneration" or alveolar atrophy. The disease is most common between thirty and fifty years of age. It is interesting to notice the great similarity in the clinic features of phagedenic pericementitis and of the oral manifestations of osteitis de- formans as described by Sir James Paget. He says, '^The surrounding gum becomes spongy, deep red, and sometimes tender ; it separates from the neck of the tooth, while at the same time the periosteum (perice- mentum) suppurates and discharges pus, which is continually oozing out around the necks of the teeth, and can be generally pressed out in great quantity. It is extremely chronic, beginning generally in early middle age and may continue for an indefinite time without influencing the gen- eral health. The early stages of the disease are sometimes attended with pain varying widely in severity. The breath is usually foul, the roots of the teeth covered with irregular masses of greenish or blackish tartar, the discharges offensive, and the whole mouth tender." 570 OPERATIVE DENTISTRY. Certain local conditions; like traumatisms, malocclusions, loss of antag- onizing teetli, unhygienic conditions of the mouth, disease of the teeth, marginal gingivitis, etc., act as local predisposing causes of the disease. Exciting Causes. — According to Black, the disease may have ''its beginning in a gingivitis that in its inception cannot be distinguished from the simple form, or its character may be marked by deposits of either salivary or seruraal calculus." The active or exciting causes of the disease, in the opinion of the writer, are local traumatisms and pyogenic infections which induce a marginal gingivitis 5 this, through, the continuity of structure, is transmitted to the already debilitated pericementum, when the conditions are favorable, through a lowered vital resistance, for the development of the pus-pro- ducing micro-organisms. Traumatic injuries of the margins of the gums, caused by the sharp par- ticles of very hard foods or the lodgement of such particles beneath the free mai-gins of the gums, the too vigorous use of the toothbrush, toothpicks, and floss-silk, or the accumulation of cervical deposits, are frequent ; such wounds and abrasions, though slight, may nevertheless readily establish, infection by giving entrance to the tissues of the pyogenic organisms of the mouth. And as debilitated tissues are prone to degenerative changes, inflammation and ulceration are readily produced. Or a marginal gingivitis may be established through a catarrhal condition of the oral mucous membrane following a general catarrhal state of the upper air-passages, induced by coryza or influenza, or it may be produced by unhygienic conditions of the mouth, the result of improper care, or by thermic irritation of the mucous membrane, induced by the ingestion of excessively hot liquids and foods. Pathology. — -An examination of the teeth which have been lost by phagedenic pericementitis may not discover any abnormal appearances, except that the roots are denuded of every vestige of the XDcridental mem- brane. They may have deposits upon their roots or they may be entirely free from them. The teeth are usually of fine organization and dense structure, and singularly free from caries. The pulp-chamber is usually small, and the pulp shows evidences of atrophy. An examination of the teeth in situ reveals the fact that upon one side the root is denuded of its pericementum to a considerable depth, while perhaps upon all other sides it is intact. This denudation of the peri- cementum is most often upon the lingual or buccal aspects of the root in the order named, while it is less rarely found upon the mesial and distal surfaces. The alveolar process is usually destroyed to nearly the same depth as the pericementum, while the edge is denuded and rough and apparently the seat "of caries, if one may judge from the peculiar odor of the pus (characteristic of bone caries) which exudes from about the mar- gins of the gums. This degenerative process sometimes destroys the pericementum and the alveolar septum between two approximating teeth, while the remaining parts are unharmed for a considerable period there- after. The pockets not infrequently extend to the apex and involve the apical space, even permitting an instrument to pass over the apex, while PHAGEDENIC PERICEMENTITIS, 571 the attacliment of the membrane to the balance of the alveolus will remain in a comparatively normal condition for an indefinite period. The formation of a pocket upon one side of the root usually causes the tooth to move out of position, the displacement occurring in a direction from the dis- eased surface. (Black.) Occasionally the entire gingival margin of the pericementum is attacked and the whole membrane rapidly destroyed, causing extrusion of the tooth and finally exfoliation. The examination develops the further fact that some of these cases have subgingival deposits upon their roots, while others do not. The formation of the deposits in these cases is evidently the result of the disease, and the calcic material is in all probability derived from the salivary secre- tions and the pus. Gingivitis is the rule wherever calcic deposits are found upon the roots of the teeth. Black thinks in these cases the phage- denic pericementitis is complicated with ''calcic inflammation," and that ''this dual condition has long delayed the recognition of phagedenic peri- cementitis as an independent disease." In those cases which do not present calcic deposits there is often an absence of gingival inflammation, and instead there is an atrophic con- dition of that portion of the gum-tissue which has lost the support of the alveolar process, which often exposes the root to the extent of the lost alveolar plate. The gums, as a rule, give little or no evidence by their appearance of the condition of the pericementum and alveolar plate lying beneath. Oc- casionally, however, the ulcerative process which has attacked the peri- cementum will be communicated to the gum and the tissue overlying the pocket rapidly destroyed. The edges of the notch thus formed in the gum-tissue will be covered with very red, coarse granulations, which bleed upon the least provocation, and are covered in the morning with an ichorous discharge. After the ulcerative process reaches the limit of the destroyed alveolar plate the edges of the gum heal and form a close union with the exposed surface of the root, thus obliterating the pocket, and in many instances controlling, and in a few others completely arresting, the further progress of the affection. This, the writer believes, is nature's method of curing the disease. Another peculiar feature of this disease, which was first pointed out by Black, is a thickening and eversion of the alveolar margins. The phe- nomenon is peculiar in that as the alveolar plate is thinned upon the sur- face lying next to the root of the tooth new bony material is laid down upon its gingival surface, so that upon examination the alveolar edge is found to be not only thickened but has the appearance of being everted. The disease is irregular in its attacks ; sometimes it will be confined for a considerable period to the side of the root of a single tooth, or of two or more teeth upon the same side of the mouth ; at others it may attack one or more teeth upon opposite sides of the mouth, — and this is the more com- mon condition, — and then spread to adjoining teeth until one by one the entire denture may be lost. This latter peculiarity of the disease has given rise to the oj)inion among some authorities that it was infectious in its nature. Neither individual teeth nor groups of teeth seem to possess 572 OPERATIVE DENTISTRY. any especial liability to be attacked by the disease, but all are equally susceptible. Witze], Black, Arkovy, Izlai, Miller, and others are of tbe opinion that the disease is essentially infectious, and that it has its origin in some specific micro-organism ; but none of these investigators has as yet been able to isolate the specific germ. On the other hand, the fact that the dis- ease shows a marked tendency to bilateral symmetry, and the teeth fii-st attacked are often not those which are most liable to ptyalogenic dei)osits, strengthens the theory of its constitutional origin. Symptoms and Diagnosis. — The most marked and characteristic symptoms of phagedenic pericementitis are a thickened and turgid condi- tion of the margins of the gums, the ulceration and destruction of the peridental membrane upon one or more sides of the root, forming deep pockets, which may reach to the apex, or the destruction of the perice- mentum may i)rogress until it encircles the entire root. The process of ulceration always begins at the cervical margin, and progresses most rapidly in a direction towards the apex. Accomi^anying the ulcerative process there is a discharge of pus and a molecular disintegration (caries) of the alveolar process. The odor of the pus is characteristic of caries of bone. The edges of the alveolar process are denuded and rough, and the disinte- gration of this tissue keeps pace with the destruction of the j)ericementum. Loosening of the teeth is an early symptom, the degree depending upon the character of the inflammation and the extent of pericemental and alveolar destruction. The gum in the early stages of the disease, as a rule, maintains its in- tegrity over those portions of the root which have lost the pericementum and alveolar plate, but in the more advanced stages recession takes place, sometimes by atrophy, at others by ulceration. When the gum is being destroyed by ulceration the margins are cov- ered with coarse granulations of an indolent character, and are covered during the intervals between meals, and in the morning, with an ichorous discharge. The discharge of pus is most abundant in those cases in which the pockets are deep and the gum intact. An atrophy or ulceration of the gum which progresses to the limit of the loss of the pericementum and alveolar plate obliterates the pocket and tends to an abatement of the symptoms of the disease. As a rule, little or no pain attends the progress of this form of pyor- rhoea alveolaris. A marked symptom of the disease is the movement or displacement of the teeth, which begins as soon as a pocket is formed at the side of the root. This movement takes place in a direction oj)posite to the surface upon which the pocket is formed, as, for instance, in a superior central incisor, if the pocket is uj)on the lingual surface, the tooth moves out- ward, if upon the mesial surface, it moves distally, etc. In other cases the tooth will turn u^^on its axis, usually in an outward direction, causing the mesio-labial angle to become most prominent when the pocket is upon the mesial surface, etc. Deposits are rarely found upon the roots of the teeth in the early stages Fig. 638. — Fibroid degeneration of the pulp from a case of pyorrhoea alveolaris. (V. A. Latham.) X 110. Fig. 639.— Human pulp m siC 65. Thrombus in vessels at A and calciflc areas at B. Blood-vessel Blood-vessel Fig. 640. — Hyaline degeneration of the pulp. (V. A. Latham.) X 100. ^Pt^;*?^ M ^ i /^ f • ^ .^ '' ^1 'f i Wtw^^ ^'"fyif j^l Pi ^ M ^L . I ^' V? jt> J^^l Fig. 641. — Ctolloid degeneration of the pulp. (V. A. Latham.) X 21.2.5. PHAGEDENIC PERICEMENTITIS. 573 of the disease, except at the cervices, but in the later stages of the chronic form the presence of dark-green deposits is the rule. In fact, the presence of deposits marks the chronic form of the disease. In the acute form de- posits are rarely or never formed upon the roots. These facts seem to prove very conclusively that calcic deposits are not the cause of this form of the disease, but are rather a consequence of it, being formed from the salivary secretions and the pus. Death of the pulj) sometimes occurs as a result of the involvement of the apical tissues in the process of pericemental ulceration, or it may occur as a result of degenerative changes. These degenerations may be fibroid in character, as shown in Fig. 638, or calcic, as seen in Fig. 639, or hyaline, as represented in Fig. 640, or colloid, as shown in Fig. 641. Under such circumstances the disease may be complicated with an alveolar ab- scess. In multiple-rooted teeth one root may be so affected while the pulp in the others may still be vital. As the disease progresses the teeth become more and more loose, until finally they are picked out with the fingers or they drop out. Differential Diagnosis. — There are two disorders affecting the peri- cementum and the alveolus which under certain circumstances might be mistaken for this disease, — viz., gouty pericementitis and alveolar abscess discharging at the cervical margin of the gum. The former may be differ- entiated by the absence usually of cervical deposits except in the later stages of the disease, nearly normal attachment of the gingival margins, hsematogenic deposits found high up in the pockets towards the apex of the root, the history of a painful swelling (abscess) upon the gum, and periodic soreness of the tooth. This may be supplemented by the family and personal history which give evidences of other gouty conditions. The latter may be differentiated by applying those tests to determine the vitality of the teeth which have been mentioned in the chapter on ^'Pulpless Teeth." Prognosis. — Very little encouragement can be given as to the perma- nent conservation of those teeth which have been once attacked by this dis- ease ; and yet by a judicious system of general and local treatment, which shall build up the debilitated condition of the body, and if possible re- establish normal function in the various excretory organs and place the teeth and the mouth in the best possible hygienic condition, much may be hoped for in the way of controlling the progress of the disease. But the common history of such cases reveals the fact that sooner or later the teeth are lost. When the disease assumes an acute type the affected teeth may be lost in a few months ; when the chronic form prevails the ultimate loss of the teeth may compass many years. Treatment. — Treatment will prove of little benefit if it is applied to the correction of the local symptoms only ; for inasmuch as the disease is influenced by or is largely due to certain abnormal states of the general sj^stem, it stands to reason that these abnormal conditions must be cor- rected if local treatment is to be of any real value. It is best, therefore, at the beginning to call for a consultation with the family medical adviser and go over the case together, and then decide* 574 OPERATIVE DENTISTRY. upon the line of general treatment which the particular case requires, leaving the conduct of this part of the case in the hands of the physician, while the dentist addresses himself to the local treatment of the oral mani- festations. By such co-operation between the general practitioner and the oral specialist a much better service can be rendered the patient than if each wrought upon the case independently and with no harmony of action. The local conditions which demand correction are malocclusion, extru- sion or rotation of the tooth, loss of antagonizing teeth, undue mobility, the presence of suppurative discharges and carious alveolar structure, foreign deposits, inflammation of the gums, and general unhygienic con- ditions of the mouth. Malocclusions are, without doubt, responsible for the establishment of the disease in many instances by exciting congestion and other inflamma- tory symptoms in the peridental membrane. The correction of the mal- occlusion by simply grinding off the opposing tooth or dressing down a filling will often give immediate relief and arrest the further progress of the disease for a considerable period. Extrusion and rotation of the teeth upon their axes is often arrested in the same manner, for many such cases have their origin in a malocclusion. Certain cases, however, seem to be dependent upon the inflammatory dis- turbances of the peridental membrane, the malposition increasing with the increasing destruction of the pericementum. Drs. M. L. Ehein and D. D. Smith have both recommended as a remedy for the correction of the abnormal conditions which iiroduce this shifting of the teeth the devitalization of the pulp. It is argued that by devitalizing the pulp the supply of blood which was originally intended for the pulp is directed to the peridental membrane, and the threatened degeneration of this structure thereby averted. The argument seems good, and clinic ex- perience tends to substantiate the argument, although there have not been, to the knowledge of the writer, any corroborated histologic data presented in proof. Loss of antagonizing teeth is a most prolific source of extrusion of the bicuspids and molars. The loss of a tooth from any cause throws its opposing fellow into disuse, and thereby predisposes it to certain diseases of the pericementum like atrophy and degeneration. The substitution of the lost teeth by a bridge or a plate often corrects these tendencies if taken in time. Undue mobility should be corrected by ligaturing, wiring, or splinting, after the manner already described. Excessive mobility of the tooth in- creases the irritation of the peridental membrane, and by that much aggra- vates the already existing morbid condition. Local treatment directed to the removal of deposits and necrotic tissue, and the sterilization of the pockets, will be of greater benefit if the teeth can be held firmly in place — put at rest— during the healing process. The treatment of the pockets is an important feature in these cases. Various opinions are held upon this part of the subject. Black * is cautious * American System of Dentistry, vol. i. p. 981. PHAGEDENIC PERICEMENTITIS. 575 not to injure the gnui margin in the removal of the deposits, but when once beyond the gum margin to use vigorous means to remove the concre- tions, not fearing to injure the tissues which line the pocket. Burchard* also offers the same suggestion. The writer has found an opposite course of treatment in reference to the gum margins to give the best results. This plan of treatment was suggested more than twenty years ago by studying certain cases in which, by atrophy or ulceration of the gum overlying the root of a tooth, the pocket had been obliterated and a spontaneous cure established. This evidently was nature's method of arresting the progress of the disease, and therefore it seemed safe to follow her leadings. From that time to this the writer has employed it many times, often with the very best results, and has to-day cases under observation which were treated by this method fifteen to eighteen years ago, and are still doing good service. Not all cases, not even a majority so treated, however, prove successful ; but where the general condition of the system can be built up to normal tone, and the patient will keep the mouth in a hygienic condition, the best results follow. The method is to excise the gum down to the bottom of the pocket by removing a V-shaped flap, the apex of the flap pointing towards the apex of the root. This exposes the denuded surface of the root and the carious edge of the alveolus, and makes it possible after the hemorrhage has ceased to find all of the concretions, remove the ulcerating pericemen- tum, and curette the carious alveolar margins. It also secures perfect drainage and makes sterilization easy. Objection has been raised to its employment upon the labial aspect of the anterior teeth, and for cosmetic reasons the objection is valid. An exposed root, with a healthy pericementum, alveolus, and gum surrounding it, is, however, a thousand times better than leaving the gum intact and with it all the disgusting features of the disease. The first cases treated by this method were superior incisors having pockets upon the lingual aspect of the root. Some of these did so well that it was tried upon the palatal roots of molars, and, as courage was gained, to all of the teeth in any location of the mouth. The method suc- ceeds best if done in the early stage of the disease, but it proves beneficial in all stages. The only serious objection to the operation being performed upon the labial surfaces of the roots of the anterior teeth is the one already mentioned, and for that reason, if the patient has a short lip and shows the gums in talking and laughing, it would prove an ugly disfigurement ; aside from this the operation may be commended. In such cases as last described the gum may be slit open from the margin towards the apex, the flaps laid back to expose the carious margin of the alveolus, as suggested by Garret- son, and the gum afterwards brought together and closed by sutures. The instruments which aie best adapted for curetting the alveolar border in this operation are hoe or spoon- bladed excavators with an angle of about forty-five degrees, or sharp chisels. During the operation the side of the blade should be kej^t close to the root in order that the gum- * Dental Pathology, Therapeutics, and Pharmacology, p. 475. 576 OPERATIVE DENTISTRY. tissue may not be unnecessarily injured. The same instruments are valu- able for curetting the alveolus in any form of operation that may be adopted. The late Dr. Allport designed a bur (Fig. 642) for the especial purpose of curetting the alveolar border by passing the instrument into the pocket from the margin of the gum. This instrument permits the '*^" ' "■ removal of the diseased border without unnecessarily injuring * either the cementum or the overlying gum. The tapering en- largement of the instrument between the bur and the shank allows the head of the instrument to be kept close to the ce- mentum without cutting its surface, and insures the certainty of a complete removal of all the carious portions of the alveolus. Effort should be made also to freshen the margin of the pericementum by passing a delicate hoe-shaped instrument of the pattern just described to the bottom of the pocket and sweeping around the denuded edge of the alveolar plate. The Dr. Aiiport's p^g^ blood, and the debris of the operation can be cleared out of the pocket by irrigating it with hydrogen dioxide, and then sterilizing with a 1 to 500 solution of mercuric chloride in water, or the same strength solution may be made in hydrogen dioxide. The Dunn medicinal syringe is a most convenient instrument for the purpose of irri- gating such pockets and of applying other liquid remedies. Caustic and escharotic i-emedies should be avoided after such an opera- tion, as in a majority of cases the application of such powerful agents would prevent the process of granulation by paving the way for the pro- duction of more necrotic tissue in the very location in which a moment before so much pains had been taken to remove it. Such kind of treat- ment in general surgery would only be considered permissible in cases of malignant disease where the surgeon felt that there was quite strong pre- sumptive evidence that all of the malignant tissue had not been removed. But if applied under any other circumstances he would expect to find his efforts to produce healing of the wound defeated by the presence of necrotic tissue, which must be again removed before regeneration could take place. Black recommended making a semicircular incision in the gum over the carious alveolar border, raising the flap and operating through this opening with sharj) chisels, and, after irrigation with hydrogen dioxide, stitching the flap in position. The main object of this operation is to remove the carious material without injuring the gum margin. The after-treatment should consist of thorough hygienic care of the mouth and the use of antiseptic stimulating and astringent mouth lotions. Tincture of capsicum and myrrh, one part capsicum to four parts of myrrh (one teaspoonful to a goblet of water), is one of the best stimu- lating and astringent lotions for this purpose. Replanting. — Treatment of this disease by extraction and replanting has been recommended from time to time, but the operation has met with such indifferent success that it has never become a popular method of treatment. The writer some ten years ago made several of these opera- tions in dispensary and private practice, and although at first they gave PHAGEDENIC PERICEMENTITIS. 577 great promise of a successful issue, all of them wei-e lost inside of two years as the result of the recurrence of the disease in an acute form follow- ing slight injuries. The methods adopted were the same as those described in the chapter on dento-alveolar abscess. Sponge-Grafting.— Dr. E. C. Briggs * and the late Dr. W. H. Atkin- son t first called attention to the use of sponge-grafts to reproduce tissue lost by this disease, and while successes were undoubtedly obtained under favorable conditions of oral hygiene, the great majority of such operations in the mouth were failures, because of the difficulty in obtaining and maintaining aseptic conditions. Electricity. — The employment of electricity in its various forms is sometimes beneficial in the treatment of those cases of the disease which Fig. 643. Improved dento-electric cautery. are free from deposits. The writer has found the best results to follow the application of the galvanic cautery to the diseased tissues of the pockets, and afterwards applying a mild faradic current to stimulate the circu- lation of the pericemental membrane. Before applying the cautery a ten per cent, solution of cocaine should be ajjplied to the pocket. Eucaine or chloretone in proper strength will answer an equally useful purpose, and be less liable to produce unfavorable constitutional impressions. After the gum has become anaesthetized the cautery-point (Fig. 643) may be applied and the current turned on for a sufficient space of time to permit the cauterizing of the margin of the peri- cementum, the whole surface of the pocket, and the carious border of the alveolus. The parts should next be irrigated, and instruction given to the patient to keep the mouth thoroughly clean by the use of antiseptic lotions, etc. The cauterized tissue sloughs away in a day or two and healthy granulations appear upon its surface. The faradic current may now be employed to stimulate the sluggish circulation of the j)ericemental membrane by applying the anode to the gum over the affected root and the cathode to the external surface beneath the jaw. The current employed should never be strong enough to be unpleasant. The duration of the treatment may be from ten to twenty minutes. Catapho- resis may also be employed with cocaine to produce local anaesthesia, and also to obtain diffusion of such drugs as are employed to stimulate the dis- eased tissues to a more healthy functional activity. * Transactions American Medical Association, 1884. t Transactions American Dental Association, 1885, pp. 152-154. 37 CHAPTER XLI. ANESTHETICS, LOCAL AND GENERAL. Definition. — Anaesthetic (Greek, av, priv., and ai(Tdavtaeat^ to feel), a substance that produces insensibility to feeling or to acute pain, diminished muscular action, and other phenomena. Ancesthesia is a state or condition of insensibility or loss of feeling due to pathologic conditions of the nerve-centres, of the nerve-trunks, or of their peripheral terminations, or to the artificial production of insensi- bility by means of the toxic effect of certain substances which temporarily inhibit the sensory functions of the nerve-centres, of the conducting paths Fig. 644. Spray apparatus — hand-instrument. of the nerves, or of their peripheral terminations. The former is termed pathologic ancesthesia, the latter surgical ancesthesia. Surgical ansesthetics are of two general classes, — viz., those which act locally at the point of application and are termed local ancesthetics, and those which act through the general system, termed general anoisthetics. Local Ansesthetics. — Various remedies have been introduced from time to time for the purpose of producing local insensibility to pain, especially for the extraction of teeth and other minor surgical operations. Most of these, however, have been discarded for various reasons, such as 578 ANESTHETICS, LOCAL AND GENERAL. 579 the unreliability of their anaesthetic power, their danger of producing general toxic effects upon the central nervous system, or their tendency to cause local gangrene and sloughing of the soft tissues. These remedies may be divided into two groups,— first, those which produce ancesthesia by the local abstraction of heat; and second, those tvhich prodiice ancesthesia through their local narcotic effect upon the tissues to which they are applied. ANESTHESIA BY THE LOCAL ABSTRACTION OF HEAT. Richardson Method.— Dr. B. W. Eichardson (1866) suggested the use of ether in a finely divided spray thrown upon the parts to be oper- FiG. (545.. Spray apparatus — foot-instrument. ated upon. This was accomplished by means of a hand or foot bellows- atomizer. Fig. 644 shows the hand- instrument : Fig. 645 shows the foot- 580 OPERATIVE DENTISTRY. instrument. The strongest ether is used, freed from alcohol and water, and mixed more or less with atmospheric air. The apparatus consists of a bottle to contain the ether, in the mouth of which a cork is fitted and perforated with two holes, through which a double glass tube is passed, one extremity of the inner part going to the bottom of the bottle ; above the cork a tube connected with the bellows pierces the outer part of the double tube and communicates by a small opening with the interior of the bottle at the inner side of the cork. The inner tube, reaching to the bottom of the bottle, delivers the ether at the extremity of the outer tube. Compression of the bellows produces two currents of air, one of which descends and presses upon the surface of the ether contained in the bottle, causing it to rise in the inner tube ; the other ascends through the outer tube and jjlays upon the column of ether as it ascends through the inner tube, converting the ether into a finely divided spray. The effect of the spray is to increase the rapidity of the evaporation, which j)roduces intense cold, abstracting the heat of the tissues to such an extent as nearly to freeze them, and thus rendering them, for the time being, insensible to pain. Ehiffolene, which is a distillation product of petroleum, is used for the same purpose and by the same means. This substance is the lightest of all known liquids ; its specific gravity is 0. 625, and it boils at 70° F. It volatilizes more rapidly than ether, and consequently reduces the tempera- ture of the tissues much more rapidly than does the ether. Special points for the atomizer have been devised for the use of the dentist, as shown in Fig. 645, which permit a spray to be thrown upon each side of the gum. Letamendi's Method. — Dr. Letamendi (1875) suggested an improve- ment upon Eichardson's method as follows : After applying a perfectly neutral sulphuric ether spray for about two minutes, he found the surface of the skin becomes red or hypersemic and is the seat of a disagreeable sensation of cold, but no sensation of burning in the part. At this stage of the process he made a slight incision in the centre of the hypersemic area with a convex-edged bistoury, eight to ten millimetres in length, but not going deeper than the capillary layer of the cutis. Almost immedi- ately there is produced an anaemic zone around the incision which enlarges outwardly. If the spray is again made to play for a few seconds over the surface which has become anaemic, the region becomes perfectly bloodless and completely anaesthetic. The advantage of this method is that the tissues become anEESthetic much sooner than by the Richardson method, and there is not the danger of so reducing the temperature as to freeze the part and thus cause death of the tissue and sloughing. Dr. Letamendi offers the following theory to account for the effect of the slight incision made in the superficial structures of the skin.* ''The abstraction of heat caused by the application of the ether spray causes relaxation and consequently dilatation of the vessels. The incision pro- duces a sudden reaction, or stimulus, which converts the extreme dilatation * Archives de Physiologie, 1875. ANESTHETICS, LOCAL, AND GENERAL. 581 into an extreme contraction, which makes the anaemia and consequently the anaesthesia complete." Arnott suggested as a substitute for ether and rhigolene a freezing mix- ture composed of ice or snow and common table salt in the proportion of two parts of ice or snow to one of salt. To be most effective it should be enclosed in a bag, one side of which should be made of rubber sheeting and the other of a coarse meshed linen or cotton cloth, to permit the water formed by the melting of the ice to drain away. In applying the bag to produce anaesthesia of the gums preparatory to extracting a tooth, the cloth side should be placed in contact with the gums and tooth, the rubber side being against the cheek, thus protecting it from injury which might result from a reduction of the temperature. The briny fluid which accumulates in the mouth from the melting of the ice may be removed by the use of the saliva ejector. These agents have given place during the last few years to the use of ethyl chloride, or mixed ethyl and methyl chloride. Ethyl chloride is con- tained in glass tubes with capil- lary points and is exceedingly ^ig. 646. by the whiteness of the tissue, when it will be found to be in a state of analgesia or anaesthesia. Ethyl chloride is inflammable and explosive, and must therefore be kept in a cool place and far from a flame. The danger from these methods lies in the fact that if great care is not exercised in applying the spray, the vitality of the tissues may be destroyed by reducing the temperature to a lower degree than living tissues can endure. It is interesting to note in this connection the high and low degrees of temperature that are safelj^ tolerated by vital tissues. If the temperature be raised above 130° F. or 140° F., and maintained for any considerable period, death of the tissue is the inevitable result. Higher temperatures act still more rapidly. If the temperature be lowered to 60° F. or 65° F., and maintained for any considerable time, the vitality of the tissue will be destroyed. (Ziegler.) Much higher and lower degrees of temperature can be safely borne by the tissues if they remain at these temperatures but for a short time. The prolonged application of the hot- water bag or of the ice-bag frequently causes death of limited areas of soft tissue, which slough and are sometimes slow to heal. ANESTHESIA BY THE LOCAL NARCOTIC EFFECT OF DRUGS. Cocaine. — "Cocaine is the chief alkaloid extract of erythroxylon coca, and when applied locally it is a powerful anaesthetic in a limited area. It resembles caffeine in its action on the nerve-centres, and atropine in its effects upon the respiratory and circulating organs. Its action is most 582 OPERATIVE DENTISTRY. rapid upon mucous tissues. Applied to the conjunctiva, it dilates the pupil and paralyzes the function of accommodation, ' ' The introduction of cocaine hydrochlorate as a local anaesthetic has to a very large extent superseded all substances previously employed for this purpose. When cocaine was first used for the purpose of i)roducing- anaesthesia for tooth extraction, it was applied to the surface of the gum, but its anaes- thetic effect did not extend beyond the mucous membrane, consequently it proved of little value, as it did not render the operation painless. Later it was employed hypodermatically in solution, when the tissues so infiltrated were found to be rendered completely anaesthetic. Immediately following its employment by hypodermatic injection, many cases were reported of the development of unpleasant and serious consti- tutional symptoms, and not a few fatal cases have been recorded as the result of paralysis of the respiratory and cardiac functions. These serious symptoms and fatal results demonstrated the fact that cocaine was one of the actively poisonous vegetable alkaloids, and that its use must be restricted to such persons as were free from pulmonary and cardiac diseases, and that the dosage needed to be greatly reduced when applied hypodermatically. It had been customary at this time to prescribe cocaine per stomach in doses of from half a grain to one grain, and hypodermatically from one- fourth to one-half a grain. The doses now administered by the stomach are from one-fourth to three-fourths of a grain, and hypodermatically from one-twelfth to one-eighth of a grain. The larger-sized dose cannot be ex- ceeded with safety to the patient. The poisonous effects of cocaine are manifested upon the respiratory and cardiac centres, and when long continued, as in the ^'cocaine habit," it produces insomnia, moral and intellectual decay, emaciation, and death. Its action is at first stimulating, and afterwards narcotic and depressing. When administered in a fatal dose it acts by paralyzing the respiratory and cardiac functions. The physiologic antidote is morphine. To neu- tralize the toxic effect of cocaine upon the respiratory centres, it is not necessary to administer a full dose of morphine ; one-twelfth of a grain is suf&cient for the purpose. To neutralize the toxic effect upon the heart and arteries, which is mani- fest in the form of tonic spasms of the muscles of these organs, one drop of a one per cent, solution of trinitrin may be added to each dose adminis- tered hypodermatically. Curtis* regards volasem — an extract of violets — as the ''natural anti- dote" of cocaine. He claims for the drug that it neutralizes the general toxic effect of the cocaine while it does not interfere with its local effect. It acts by stimulating the heart action and the respiratory movements, contracts the arterioles, and raises the blood pressure. Administered in five-drop doses immediately before the cocaine injection, it is claimed to effectually prevent the general toxic effects of this drug, and in cocaine poisoning is an efiScient antidote. * International Dental Journal, 1900, p. 613. AN-JESTHETICS, LOCAL AND GENERAL. 583 Experience in the use of cocaine administered hypodermatically for the extraction of teeth and other minor surgical operations has proved that the smaller dose — one-twelfth of a grain and even less — is just as effective in producing a local anaesthesia as is the larger dose ; while by the employ- ment of the smaller dose the dangers of developing constitutional symp- toms are entirely overcome, except in those cases in which there exists an idiosyncrasy against this drug. The writer has found from a large experience with cocaine, both in the extraction of teeth and in surgical operations, sometimes of considerable magnitude, like the extirpation of cancerous growths of the lips and jaws, that a one or two per cent, solution of cocaine is just as efdcient as a four or even a ten per cent, solution. When the area to be anaesthetized is large and there is a possibility of exceeding a medium dose, a one per cent, solution may be employed. In extracting teeth, two to three minims of a two per cent, solution should be injected upon each side of the jaw, care being taken to keep the needle close to the alveolar process, as by this method better results are obtained than when the injection is made nearer the external surface. In operations for the removal of tumors, a one per cent, solution can be used, but double the quantity employed, and the in- jections made at several different points. The one-twelfth of a grain dis- solved in a drachm of sterilized water is more efficient than the same dose in one-half the quantity of the menstruum. By using a standard solution the dose may always be accurately gauged, and the possibility of an overdose being administered entirely obviated. The galvanic current as applied in cataphoresis hastens the anaesthetic action of the drug and makes it more profound. For the methods of its application the reader is referred to the chapter on Hypersensitive Dentin, Cocaine solutions are liable to spoil, if kept for any length of time, by the development of fungi. It therefore becomes necessary to add an effi- cient antiseptic to solutions that are intended to be permanent, as sterili- zation by heat cannot be employed without producing chemic changes in the cocaine which destroy its character. Boiling causes it to split up into methyl, benzoic acid, and ecgonine. By using a one-half per cent, solution of carbolic acid as the vehicle for making the cocaine solution the devel- opment of fungi is entirely prevented, and such solutions will keep for weeks without change. Burchard recommends the following prescription : R Cocainse hydrochloric!. , gr. | ; Morphinse sulph. , gr. j\ ; Or atropinse sulph., gr. yi^ ; Trinitrin (one per cent, solution), gtt. i ; Acidi carbolici, gtt. i ; * Aquae, ad q. s. Sig. — The above represents a half-syringeful, and is a full dose. Tropacocaine is derived from the small-leaved coca of Java. It pos- sesses a decided advantage over cocaine as a local anaesthetic in that it is considerably less toxic in its effects, has but a slightly depressant action upon the cardiac functions, and is free from any paralyzing effect upon the 584 OPERATIVE DENTISTRY. function of respiration. As an ansesthetic it is more rapid in its action than cocaine, but it is not so persistent in its effects. The dose is from one-third to two-thirds of a grain. It is made in solution with sterilized water, and the drug is of itself slightly antiseptic. Eucaine. — Eucaine hydrochlorate ''A" is a synthetic body of similar chemical constitution as cocaine, and the observed similarity in this re- spect was the means of causing experimentation with it as to its value as an ansesthetic and mydriatic. It is a white, neutral, crystalline powder, soluble in ten parts of cold water, about nine per cent. It is preferred by many ophthalmologists to cocaine for all purposes in which this drug is used, as its toxic effects are less powerful, while its ansesthetic and mydri- atic powers are more persistent than those of cocaine. Its physiologic effect upon the central nervous system is primarily one of exaltation, as shown in a quickened heart-beat, and secondarily of depression and paralysis. Locally it produces hypersemia of the capilla- ries, while cocaine produces ischaemia. Solutions of eucaine are made in distilled water, and are much more stable than those of cocaine. Sterilization by boiling does not decompose the eucaine. The maximum dose hypodermatically is from one-fourth to one-half a grain. It is employed in dental surgery in from four to nine per cent, solutions. Solutions stronger than nine per cent, are not stable^ and will separate crystals of eucaine. Beta Eucaine. — Eucaine hydrochlorate ''B'' is a similar synthetic body to eucaine "A." It is a white, neutral crystalline powder, soluble in from twenty-seven to twenty-eight parts of cold water — three to four per cent. — at ordinary room-temperature. The toxicity of eucaine "B," according to the experiments of Drs. Dumont and Legrand, is 3.75 less than that of cocaine, and about three times less than eucaine ''A," while its anaesthetic effect is equally rapid, but of shorter duration. It is complete in from three to five minutes, and disappears in from ten to twenty minutes. Later experiments place the toxic effect of eucaine " B" at five times less than that of cocaine. It is employed hypodermatically in dental surgery in solutions of one-tenth to one per cent. The dose usually employed is one to two centigrammes (one-sixth to one-third of a grain) of a one per cent, aqueous solution. Chloretone (acetonchloroform, or trichlor tertiary butyl alcohol) is an- other synthetic compound, prepared by Parke, Davis & Co., and "is formed when caustic potash is slowly added to equal weights of chloroform and acetone, and may be isolated from this mixture, after the removal of any excess of acetone and chloroform, by distilling with steam. Obtained in this manner, it is a white, crystalline compound, having the odor of camphor. When freed from water by melting and allowed to cool, the camphoraceous odor is more pronounced, and its general appearance re- sembles camphor more closely. It is very soluble in chloroform, acetone, strong alcohol, ether, benzine, and glacial acetic acid, sparingly soluble in cold water (one per cent.), more soluble in boiling water. Dilute acids and alkalies are apparently without effect ; concentrated sulphuric acid decomposes it." (Houghton and Aldrich.) ANESTHETICS, LOCAL, AND GENERAL. 585 Chloretone possesses hypnotic and general and local anaesthetic proper- ties. Its general effects are mainly confined to the central nervons system, differing only from most of the other hypnotics and anaesthetics of the fatty acid series in that it has little or no depressing effect upon the circulatory system. Experimentation has shown that chloretone has a selective action for the central nervous system, as more of this drug was found in the brain in several instances than in any other organ of the body. Its local anges- thetic properties are of a high order and in many respects resemble those of cocaine. It also possesses marked antiseptic properties, and for this reason is free from the objection sometimes raised against solutions of cocaine used for hypodermatic injection, — viz., that abscess and sloughing sometimes follow its employment. Chloretone may be used hypodermatically in all cases where cocaine can be employed, while it is free from the serious objection to cocaine in that it has little or no depressing effect upon the action of the heart. In dental surgery it may be employed locally for obtunding hyper- sensitive dentin and producing ansesthesia of the dental pulp preparatory to its surgical extirpation and for the extraction of teeth. For obtunding hypersensitive dentin and anaesthetizing the pulp, a solution is prepared by mixing equal parts by weight of sulphuric ether and chloretone crystals. This is applied upon a pledget of cotton after the rubber dam has been adjusted. It may also be applied cataphorically after the manner of cocaine. For extracting teeth, a solution may be prepared by mixing fifteen per cent, of alcohol with eighty-five per cent, of distilled water, and adding enough chloretone to form a saturated solution. (Leo.) The dose of this solution (one per cent.) hypodermatically is from fifteen to twenty-five minims, and the full local anaesthetic effect is obtained in from one to three minutes. The dose of the crystals per stomach for its anodyne and hyp- notic effect is from five to fifteen grains, administered in capsules or tablets. In the employment of anaesthetic drugs which are applied by hypoder- matic injection, the operation must be performed under the strictest anti- septic precautions, in order to preclude the possibility of septic infection. The surface to be punctured should be cleansed and rendered aseptic by repeated washing with one of the common antiseptic solutions. The syringe should be of metal throughout — cylinder and j)iston— so that it may be sterilized by boiling ; any other form of syringe cannot be sub- jected in all of its parts to such a process without spoiling it, and unless so treated it is unsafe to use. The solutions employed should also be sterile, otherwise abscesses may follow their injection into the tissues. The immediate dangers from the hypodermatic injection of any of these drugs are their toxic effects, and these may develop at any time and when least expected. The operator should therefore be prepared at all times with such remedies as may be useful in combating these effects. The symptoms of cocaine poisoning are dizziness and sense of faintness, great pallor, rapid and feeble pulse, bluish-white lips, cold perspiration, spasmodic respirations, and syncope. To combat these symptoms, diffusi- 586 OPERATIVE DENTISTRY. • ble stimulants are called for, such as aromatic spirit of ammonia and whiskey or brandy. The aromatic spirit of ammonia may be administered in doses of from one-half to one fluidounce in water, or whiskey or brandy in doses of from one to two fluidounces. If the patient cannot swallow, one-half of this amount of whiskey or brandy may be administered hypodermatically. When the heart action is very weak, sulphate of strychnine, one-hundredth of a grain in a drachm of whiskey, or digitalin in doses of from one- hundredth to one-fiftieth of a grain, may be administered hypodermatically. The tendency to fatal syncope may be combated by the inhalation of amyl nitrite in doses of from two to three minims dropped upon a napkin and held under the nose. This remedy is also put up in tiny glass flasks or pearls containing three minims each, which may be crushed upon a napkin. If these measures fail, artificial respiration and electricity should be employed, and further stimulation of the nerve-centres attempted by the hypodermatic injection of nitroglycerin in doses of one-half minim to one minim of a one per cent, solution, increased to two minims if necessary. GENERAL ANESTHETICS. The substances which are commonly used for the purpose of producing general anaesthesia are chloroform, ether, and nitrous oxide gas; various other substances have been introduced and tried for the same purpose, but none of them has ever enjoyed popular favor. Among these substances may be mentioned amylene {pental^, carbon tetrachloride, chloral hydrate, ethene chloride, hydrohromic ether (bromide of ethj^l), and various mixtures of alco- hol and chloroform, and alcohol, chloroform, and ether. The substances which are most commonly used in the practice of dental surgery are nitrous oxide gas (N.^O) and sulphuric ether (C^HJ^O. Chloroform (CHCI3) is rarely used in the extraction of teeth or other operations which require for their performance a sitting position, on account of the depress- ing effect of the drug upon the functions of the heart. These dangers are, however, greatly lessened if the patient can be kept in a recumbent posi- tion during the entire period of anaesthesia. Infants and little children bear chloroform better than adults, and in many ways it acts more kindly upon little children than any other anaesthetic. Chloroform has proved itself to be so unsafe for dental operations upon adults that it is rarely used at the present time for these x>urposes. IS'itrous oxide gas and ether are so much safer, and so completely fill the requirements of anaesthetics in both brief and prolonged operations, that there is no need of running the risk of a fatal accident by employing chloroform when comparatively safe remedies may be used in its stead. Nitrous Oxide Gas. — This substance is the safest of all of the anaes- thetics employed for dental purposes that have so far been discovered. It suffers no chemical change at the temperature of the body or during its inhalation. Its only drawback is the fact that the anaesthesia produced by it is of such short duration — usually from thirty to sixty seconds— that it can be employed only in momentary operations, like the extraction of teeth, the lancing of an abscess, or the extirpation of a vital pulp. For ANAESTHETICS, LOCAL AND GENERAL. 587 this reason it has but little place in general surgery. It has been used in operations for strabismus, the removal of small tumors, for painful exami- nations, the setting of a recent luxation, or the performance of a tenotomy ; but in all operations requiring more than a very few minutes ether is to be preferred, as with this substance anaesthesia may be maintained for an hour or two if required. Nitrous oxide gas is made by the fusion of granulated ammonium nitrate in a glass retort, the gas being passed through three wash-bottles contain- ing water and collected in a small gasometer. The manufacture of the gas requires very close attention to obtain it in a pure state. The most common impurities likely to be found in the gas are chlorine and nitric oxide, and for this reason every sample of ammo- nium nitrate used should be tested for chlorine before using it, and the greatest care exercised not to allow the heat to rise above 482° F. , as nitric Fig. 647. Fig. 648. oxide is given off above this degree of heat. For the comj)lete process ot its manufacture the reader is referred to works on chemistry. Since the introduction of liquefied nitrous oxide gas few dentists manufacture the gas for themselves. The liquefied gas is so universally pure, that the dentist feels he can obtain a better article than he can manu- facture for himself ; while it is in such a convenient form to handle, and the apiDaratus takes up so little space in the operating-room, that there is no longer any need of his consuming his time in its manufacture or filling his office with a cumbersome apparatus. Nitrous oxide gas, when properly employed, is almost, if not entirely, free from danger, and is rarely productive of those disagreeable symptoms of nausea and depression which so commonly follow the administration of ether and chloroform. - There are several forms of apparatus used for administering nitrous oxide, both for that made in the usual manner and for the liquefied gas. Fig. 647 represents one of the most commonly used office apparatuses, while 588 OPERATIVE DENTISTRY Fig. 648 represents a portable apparatus which may be carried in the hand. In the former the condensed gas is discharged from the cylinder into a gasometer, and the gas drawn from the gasometer through a flexible rubber tube and the inhaler. In the latter the gas is discharged into a rubber bag to which are attached a flexible rubber tube and an inhaler. The inhaler is the most important part of the apparatus, and should be so constructed as Fig. 649. to admit or exclude air at the will of the operator. It should also be armed with a stop-cock by which the gas may be turned off, and an auto- matic valve whereby the expired air may be expelled and prevented from entering and mixing with the gas as it passes through the inhaler. Fig. 649 represents an inhaler with a removable lip-shield, while Fig. 650 represents an inhaler having a face-piece or hood which covers not only Fig. 650. Fig. 651. the mouth, but the nose as well. The advantage of the former lies in the fact that when the lip-shield is removed the lips can be lightly comi^ressed around the mouth-piece by the fingers of the operator, and it also gives a full view of these i^arts, so that the changes in their color, as shown in the mucous membrane, can be carefully watched and those symptoms noted which indicate the lack of oxygen and the accumulation of carbonic acid AK.^STHETICS, LOCAL AND GENERAL. 589 in the blood. Cyanosis of the lips, stertorous breathing, and jactitation, etc., are the danger signals. In the latter instrument the face-piece or hood is a serious disadvantage, in that it covers the mouth and nose, making it impossible to watch the effects of the gas upon the blood, while in those patients who wear a beard it is imjDossible to exclude the admission of air. Occasionally, as in cases of harelip, or when the orbicularis oris muscles are so much swollen that it is impossible to close the lips about the mouth- piece, the hood becomes of great service. Fig. 651 shows the mechanism of the inhaler. Hewitt's Method. — Dr. Hewitt, of London, England, believing that the symptoms of asphyxia which so often accompany the administration of nitrous oxide gas might be overcome by the admixture of a proper amount of oxygen with the gas, devised an apparatus by which oxygen can be mixed with the gas in various proportions. The apparatus (Fig. 652) consists of three cylinders of compressed gas, two filled with nitrous oxide and one with oxygen, the valves of which are Fig. 652. under the control of the foot of the operator. Connecting the cylinder with the rubber inhaliug-bag, which is divided into two compartments by a rubber septum, is a double tube for conveying the gases to the bag. To the upper end of the inhaling-bag is attached a mixing-chamber, and to this is attached the mouth-piece or inhaling-tube. When about to administer the gas, the valves of the mixing-chamber 590 OPERATIVE DENTISTRY. Fig. 653. are closed. Oxygen is then let into one compartment of the inhaling-bag- until it is nearly- full aud nitrous oxide into the other. The inhaling-tube is then placed in the mouth of the patient, who is instructed to make long, full, deej), and steady inspirations and expirations, the nose being closed with the thumb and finger of the operator, and the valve of the mixing- chamber (Fig. 653) so changed that only air is breathed for a few inhalations. The indi- cator is then pressed downward to the notch, which cuts off the air, and the patient now breathes only the pure nitrous oxide. After a few inhalations the indicator is carried still further downward to the second notch, which permits the passage of one part of oxygen to mix with the nitrous oxide. If the indicator is carried downward to the third notch, two parts of oxygen are mixed with the nitrous oxide, and so on until the patient receives the amount of oxygen necessary to pre- vent the appearance of the symptoms of asphyxia. The amount of oxygen required to prevent these symptoms varies considerably with each indi- vidual ; some require more, others less, and the amount varies also with the stage of the anaesthesia. The first symptom and the best guide to the condition of asphyxia is the cyanotic appearance of the lips and face. Similar advantages may be gained by the admission of atmospheric air in proper quantity and at the right time during the x3roduction of anaesthesia, but it is not possible to prolong the anaesthesia for so long a period as by the Hewitt method. EXAMINATION OF THE PHYSICAL CONDITION OF THE PATIENT. Before administering a general ansesthelic the condition of the patient should be ascertained by a critical physical examination, and if there is found to be present any serious functional or organic affection of the heart, of the lungs, or of the kidneys, ether and chloroform are contraindicated. Mtrous oxide may, however, in some of these cases be used with success, but there can be no positive assurance that a successful issue will follow its administration. It is better, therefore, in all such cases as would naturally come under the care of the dental surgeon for operation in which serious diseases of the heart, lungs, or kidneys exist, to use a stimulant to brace the patient for the ordeal of the operation, rather than to take the chances of administering an anaesthetic. The shock incident to the extraction of a tooth or the lancing of an alveolar abscess may be prevented in great measure, if not completely, by ANESTHETICS, LOCAL AND GENERAL. 591 the administration of stimulants or anodynes to such patients as cannot with safety take an anaesthetic. Ether is positively contraindicated in bronchial and pulmonary dis- eases and in diseases of the kidneys, and chloroform in diseases of the heart. For surgical operations which must be performed to save life, ether is the safest anaesthetic for patients suffering from functional or organic disease of the heart, while chloroform is safest for those suffering from bronchial and pulmonary diseases and affections of the kidneys. If the dentist does not feel that he is competent to decide the question of the physical condition of the patient, he should consult with the family physi- cian in relation to the matter, and if the patient has no family physician, it is best to divide the responsibility of the case by calling in some other physician to make the examination and administer the anaesthetic. PRECAUTIONS AGAINST ACCIDENTS. Anaesthetics should never be administered just after eating, as vomiting may be induced, and as a result particles of food may be drawn into the larynx on taking a deep inspiration and asphyxia be the result. If nitrous oxide is used, the dentist should never assume the double responsibility of administering the anaesthetic and performing the opera- tion alone. An intelligent and capable assistant should always be pres- ent. If ether or chloroform is used, the patient requires the undivided attention of the person who administers the anaesthetic, while the operator should not have his mind distracted by the care of the patient while under the anaesthetic. There is also another reason why in operating upon females under the influence of an anaesthetic the operator should not be alone, but should have another person present, preferably a nurse or a friend of the patient. I^ot infrequently hallucinations and erotic desires are stimulated by the effects of the anaesthetic, and the patient clings to the delusion that an indecent assault has been made uj^on her while she was in a helpless condition from the anaesthesia. The operator, therefore, if he would guard himself against unjust reproach and a serious criminal charge, should see to it that some friend of the patient is present during the operation. Before beginning the administration of any general anaesthetic, the mouth should be examined for the j)resence of artificial teeth, especially partial plates, as failure to take this precaution has in several instances resulted in a fatality from the plate becoming dislodged and falling into the larynx or becoming lodged in the oesoj)hagus. In the administration of nitrous oxide a mouth-prop (Fig. 654 or Fig. 655) is necessary to keep the mouth oj)en during the operation. This should be applied before the mouth-piece is placed in position, so that when anaesthesia is complete no time will be lost in efforts to pry the mouth oj)en to insert the prop. Props made of wood or vulcanite are the best ; they should have a long string securely fastened around the centre by which they may be withdrawn if by accident they should be dislodged and fall into the fauces. Clothing which is tight at the throat or the waist should be loosened, 592 OPERATIVE DENTISTRY. that there may be no obstruction to the most perfect movements of breath- ing. In the extraction of teeth, and particularly of roots, the operator should use the utmost care to prevent the tooth or root from slipping from the forceps and falling into the larynx, and when the elevator is used to dis- FiG. ()55. Fig. 654. Mouth-prop (Dr. S. H. Guilford pattern). Dr. Daintree pattern. lodge a root, it should be removed from the mouth before another is extracted, for if left in the mouth it might fall into the larynx or be drawn in by a quick inspiration, and the patient die from asphyxia before it could be removed or relief obtained by tracheotomy. Fig. 656. ADMINISTRATION OF ETHER. In favorable cases which require operations that consume more time than would be allowed by nitrous oxide anaesthesia, sulphuric ether is the safest and best anaesthetic that can be employed. This substance may be administered by means of a cone (Fig. 656) formed of a towel or a folded news- paper, in which a napkin has been folded or a sponge has been placed and secured with an ordinary pin or a safety-pin. The napkin or sponge is saturated with ether, care being taken not to put on so much as to cause it to drip upon the face of the patient. It is then slowly advanced to the face of the patient, allowing plenty of air to be inspired with the ether vapor until the air-passages become accustomed to the irritation and the tendency to cough has passed away. It may then be brought close to the face and all air excluded ex- cept that which passes through the open end of the cone and through the sponge or over the surface of the napkin. In this way the patient receives a sufficient amount of oxygen to support the functions of life, while at the same time the air is thoroughly im- Towel done up as a cone. ANESTHETICS, LOCAL AND GENERAL. 593 pregnated with the ether vapor, and the patient is rapidly brought under its influence. Various forms of inhalers have been introduced from time to time for the administration of ether, the best of which are the Lente (Fig. 657) and the AUis (Fig. 658). The Lente inhaler is a cone made of sheet brass, fitted with a rubber air-cushion around the edge to exclude the air from entering between the cone and the face, while the upper end has an opening fitted with a cork- stoppered tube large enough to admit sufficient air. When in use the cone is lined with a piece of sheet lint or cotton, held in place by a piece of wire or whalebone slipped in, and long enough to curve upward, so as to keep the cotton from touching the face. The cotton lining is saturated Fig. 658. Fig. 657. Lente's inhaler. Allis's inhaler. with ether, and the apparatus is ready for use. Additional ether may be supplied through the open tube without removing the apparatus from the face, but great care must be exercised not to pour on more ether than the cotton will absorb, as there is danger of its running into the throat and causing asphyxia. The Allis inhaler "consists of a wire framework sufficiently large to cover the lower part of the face ; these wires are parallel, and about one- quarter of an inch apart. Between the wires and from side to side a strip of muslin bandage, two and one-half inches wide and three yards long, is passed. The wire frame is five inches long by three inches at its greatest width. Outside of the wire frame there is a covering of sheet brass, and over this another metal cover with a cushioned edge to fit over the face, covering both the nose and mouth, as shown in Fig. 659. When ready for use, the top is left open for the free entrance of air and for supplying the ether from without." Many times, if the confidence of the patient can be secured beforehand, a tooth may be extracted, an abscess opened, or a pulp extirpated before the patient loses consciousness, as sensation to pain is lost long before this stage of complete ansesthesia is reached. In serious operations, however, profound anaesthesia is necessary in order to prevent shock and to obtain perfect control of the patient during the operation, as struggling or the 38 594 OPERATIVE DENTISTRY. spasmodic contractions of the diaphragm and abdominal muscles incident to efforts to vomit caused by nausea are great hinderances to a delicate operation. During the stage of excitement or when the contractions of the abdo- minal muscles indicate the existence of a tendency to vomiting, the anses- thesia should be hastened, in order to allay these symptoms and secure complete anaesthesia as quickly as possible. Complete anaesthesia may be recognized by placing the surface of a finger upon the conjunctiva of the eye, when, if sensation is not present, no contraction of the muscles of the lids will be observed. Complete relaxa- tion of the muscles is another indication of complete anaesthesia. This may be demonstrated by raising an arm, which will immediately fall if complete relaxation of the muscles has taken place. When the stage of muscular relaxation is reached there is a tendency for the lower jaw to drop and the tongue to fall into the fauces, which Fig. 659. Allis's aseptible ether inhaler, all metal. by its pressure upon the larynx and the glottis causes obstruction to breathing. This tendency of the jaw to drop may usually be overcome by placing the fingers upon its under side midway between the angle and the mental foramen, and bringing the teeth of the lower jaw in contact with those of the upper, and supporting it in that position. If the tongue falls into the fauces, it should be grasped with the tongue-forceps and with- drawn, and so held until muscular relaxation has passed. Dilatation of the pupil and stertorous breathing are danger signals, in- dicating that the limit of safety has been reached. The ether should there- fore be withdrawn, and the free administration of atmospheric air allowed. If the respirations cease and cyanosis of the lips and face is present, the tongue should be quickly grasped with a tenaculum or tongue-forceps, and the organ drawn well forward ; this oj)ens the rima glottidis and allows free entrance of air. If, however, breathing does not immediately begin again, artificial respiration must be instituted and maintained until nature re-establishes the normal physiologic process. Other methods which may be employed to resuscitate the patient have already been described in an earlier part of this chapter under the head of cocaine anaesthesia. CHAPTEE XLIL EXTRACTION OF TEETH. The operation of extracting teeth is one which requires experience, skill, good judgment, and an accurate knowledge of the anatomy of the teeth and of the contiguous parts. An operator who attempts to extract teeth without this exact knowledge will prove himself a bungler, and be the means of causing great suffering and irretrievable injury to the integ- rity of the remaining teeth and to the jaws. For these reasons it is very important that the operator thoroughly understand : 1. The anatomy of the teeth and their most common anomalies. 2. The relations of the roots of the teeth to the jaws. 3. The indications which call for the extraction of teeth. 4. The selection of the proper instruments with which to extract indi- vidual teeth or roots. 5. The proper adjustment of the instrument to the tooth or root. 6. The proper kind and direction of the force to be applied, and the lines of least and greatest resistance of the alveoli. 7. The difficulties, complications, and accidents which are liable to occur in the operation. The anatomy of the teeth and their anomalies, and the relations of the roots of the teeth to the jaws, have already been discussed in Chapter I., to which the reader is referred. INDICATIONS WHICH CALL FOR THE EXTRACTION OF TEETH. The indications for tooth extraction are dependent upon such varied conditions, both local and general, that no arbitrary rules can be laid down by which to decide the many questions involved. All that can be done in this direction to assist the practitioner and the student is to suggest those conditions which most imperatively demand the operation. Deciduous Teeth. — There are certain conditions which demand the extraction of the permanent teeth which do not appear in relation with the temporary teeth by reason of their deciduous nature and function. The most important conditions which call for the extraction of the deciduous teeth are : 1. When the teeth are the seat of alveolar abscesses which do not respond to appropriate treatment. 2. When from other causes they are a source of continued irritation, affecting the comfort or the general health of the patient. 3. When the retention of the deciduous teeth is causing the permanent teeth to erupt out of their normal position. 4. When a deciduous tooth is retained long past the normal period for its exuviation by reason of the non- eruption of its permanent successor, 595 596 OPERATIVE DENTISTRY. and it is becoming wedged between its immediate neighbors as a result of the approximal inclination of these teeth. Permanent Teeth. — The most important conditions which call for the extraction of the permanent teeth are : 1. When a tooth or roots of a tooth are the subject of a chronic alveolar abscess which does not respond to treatment, or when there is in the upper jaw an abscess which dischai'ges into the antrum or the nasal fossa. 2. When a tooth is the subject of an acute alveolar abscess of malignant type, which threatens to cause acute septiccemia. 3. When a tooth is rendered useless from extrusion caused by the loss of its antagonist and a proper occlusion cannot be restored by artificial means, or it has become very loose from resorption of the alveolar pro- cess or from pyorrhoea alveolaris. 4. When a tooth or the roots of a tooth have become useless for the purpose of crowning, bridging, or supijorting a plate, by reason of the presence of fungoid growths of the pulp or the gum or of their gradual destruction by resorption. 5. When a tooth is the subject of hypercementosis which causes a per- sistent neuralgia. 6. When a tooth is the subject of a persistent odontalgia dependent upon pulp-nodules or a pulpitis which does not respond to treatment and is causing serious reflex or constitutional irritation. 7. When an erupting tooth is retarded by reason of insufficient room in the alveolar arch or the impingement of another tooth, and it is causing irritation and pain or acute deep-seated abscess of the jaw. This applies most often to the third molars, particularly those of the lower jaw. 8. When it becomes necessary to sacrifice certain teeth to i)erfect the alignment of the dental arch. 9. When the first permanent molars in children under eleven or twelve years of age — before the second molars are erupted — i^resent with exposed pulps or alveolar abscesses. Under such circumstances all of the first per- manent molars had better be extracted, as such a procedure will result in a more perfectly formed arch and a better occlusion than if only the offend- ing tooth is removed. The writer is aware that there has been considera- ble discussion upon the advisability of such a course of treatment ; but he believes, after many years of experience and close observation of the re- sults of both of these lines of treatment, that the best results are obtained by the extraction of all of the first permanent molars. After the second molars have erupted the extraction of the first molars is unadvisable, except when the teeth are causing serious local or con- stitutional irritation, for after their removal there is a tendency for the second molar to tilt forward, forming an inverted V-shaped space between itself and the second bicuspid, and preventing a normal occlusion of the mesial cusps. 10. When it is necessary to remove certain sound teeth preparatory to inserting an artificial denture. Under such circumstances the teeth that should be removed are : (1) all roots which would be covered by the denture, except those which might be EXTRACTION OF TEETH. 597 utilized to carry a crown or form an abutment for a bridge ; (2) all teeth which have been rendered unsightly or loose by reason of the resorption of the gums and the alveolar processes ; (3) all teeth that have become so far extruded from their alveoli as to render it impossible to place occluding artificial teeth in the opposing jaw ; (4) a single tooth or two teeth standing together, when they are the only teeth remaining in the upper jaw. This applies particularly to the incisors, cuspids, and bicuspids. Molars may often be left with advantage if they have occluding natural teeth ; (5) when one tooth remains upon either side of the upper jaw — if they are in good position and of proper shape to receive a clasp or give support to the plate — they should not be extracted ; (6) when a single tooth remains in the lower jaw, or a single tooth upon either side, it is advisable to retain them, especially if the patient is about to have inserted the first lower plate, as such teeth are valuable for supporting the denture by means of clasps, until such time as the patient becomes accustomed to it. GENERAL CONDITIONS UNFAVORABLE TO EXTRACTION. Certain systemic conditions are generally regarded as unfavorable to the extraction of teeth, for the reason that the operation may under these circumstances aggravate an existing morbid condition, set in operation a train of unfavorable symptoms, or establish a dangerous and perhaps fatal complication. The systemic conditions which are most liable to cause unfavorable results from the extraction of teeth are : I. General debility. II. Nervous irritability. III. Organic disease of the heart. IV. EiDilepsy. Y. Hemorrhagic diathesis. VI. Pregnancy. I. General Debility. — This is a condition which greatly predisposes the individual sufiering from it to nervous depression and shock. In a large majority of these cases the vital forces are depressed, the nervous system is in an irritable condition, and the heart action weak. It therefore becomes necessary in these cases to prescribe tonic treatment in the form of iron, quinine, and strychnine, to prepare the patient for the ordeal of the opera- tion. If, however, an immediate operation is imperatively demanded, stimulants should be administered and the operation performed under an anaesthetic. II. Nervous Irritability. — General nervous irritability may be an inherited condition or diathesis, or one which is the result of morbid con- ditions of the system induced by disease, great nervous strain, overwork, and such like circumstances. In either case the affection is a manifestation of a debilitated condition of the nerve-centres calling for general tonic treatment, such as that just indicated, to build up the system ; and seda- tives, such as potassium bromide, asafetida, and valerianate of ammonium, to control the more irritable nervous manifestations. Operations upon such 598 OPERATIVE DENTISTRY. individuals not infrequently result in severe shock to the nervous system, resulting in chorea, hysteria, or more serious nervous affections. III. Organic Disease of the Heart. — Inorganic disease of the heart in any of its many forms, — hypertrophy, fatty degeneration, valvular in- sufficiency, etc., — there is great danger of shock in even trivial operations. It therefore becomes necessary, whenever the operation of tooth- extraction is imperatively demanded, that every precaution be taken to guard against shock and its possible fatal termination. The nervous excitement and fright incident to the contemplation of the operation in individuals suffer- ing from a weak heart are sometimes sufficient to produce fatal shock. For these reasons the dental practitioner should never permit himself to oper- ate upon such individuals without the knowledge and co-operation of the patient's family physician. Such an association is a safeguard, in case of a serious or fatal termination of the operation, against unjust criticism or a suit for supposed malpractice. Whenever a tooth has to be extracted for a person suffering from any organic heart affection, it becomes necessary to administer cardiac stim- ulants, such as whiskey or brandy, aromatic spirit of ammonia, digitalis, strychnine, or a one per cent, solution of nitroglycerin. To obtain the best results, some one of these agents should be prescribed an hour or two before the contemplated operation. The operator who is thoroughly prepared for all emergencies will have a hypodermic syringe charged with a tablet containing one-fiftieth of a grain of digitalis or one-fiftieth of a grain of strychnine sulphate dissolved in one drachm of whiskey or brandy, or with the following combination (also put up in tablet form by Nelson, Baker & Co., of Detroit, Mich.). R Digitoxin, gr. ^^ ; Nitroglycerin, gr. ^i^ ; Strychnine sulph., gr. j^^. Dissolve in one drachm of distilled water. This combination is an exceedingly efficient remedy in cases of threat- ened heart failure, shock, or collapse, and should find a place in all emer- gency outfits. IV. Epilepsy. — Individuals who are so unfortunate as to be the sub- jects of epilepsy may be prepared for the operation by the administration of large doses of potassium bromide, which will in many cases, for the immediate time at least, prevent or mitigate the severity of an attack. Nitrite of amyl, if applied during the convulsion, will sometimes cut the attack short. The nervous condition of these poor unfortunates is such that anxiety, fear, or the shock of an operation is prone to bring on an attack ; it is therefore unwise for the dentist to undertake the extraction of a tooth without the presence of the family physician or some other medical adviser. In case an attack comes on, all that can be done is to place the patient in the recumbent position, protect him against injury during the paroxysm, and prevent the laceration of the tongue and other soft tissues of the mouth from the spasmodic closing of the jaws. This may be ac- EXTRACTION OF TEETH. 599 complished by placing a piece of soft rubber between the teeth, or a roll of bandage or other such material. V. Hemorrhagic Diathesis.— The hemorrhagic diathesis is due to deficient muscular tone in the coats of the blood-vessels, and to a lack of a normal coagulability of the blood. This diathesis may be hereditary or acquired, and it usually first shows itself at about the period of second dentition. It is a condition which often causes great anxiety and alarm to the operator, the patient, and the friends, as many cases of fatal hemorrhage following tooth-extraction in these individuals have been recorded. When the operator is aware of the diathesis he can usually, by appropriate treat- ment instituted a few days before the contemplated operation, control the tendency to hemorrhage by improving the tone or contractility of the blood-vessels and restoring the normal coagulability of the blood. A pill containing from ten to twenty grains of gallic acid and one grain of opium may be administered after each meal for three days, or the fluid extract of ergot may be given in doses of from twenty drops to one flui- drachm every two to four hours on the day previous to the operation. Ergot, however, must not be administered to pregnant females, on account of the danger of producing an abortion. VI. Pregnancy. — Women who are performing the functions of men- struation, gestation, or lactation should as far as possible be shielded from all operations. During the period of menstruation most women are in a peculiarly nervous condition, and much more susceptible to irritation and shock than at other periods. Vicarious menstruation from the alveolus of a recently extracted tooth has also been recorded. Many cases of premature labor have been placed on record as the result of shock from the extraction of a tooth, while congenital deformities and monstrosities have been charged to the same cause. A very slight nervous or mental shock is sufficient in some women to produce premature labor, while in others even a severe shock makes no impression. It is safer, however, under all circumstances requiring operation upon pregnant women to administer a general anaesthetic, and thus prevent the shock which would be likely to occur from the operation. During lactation mental anxiety, nervous irritation, and shock are liable, through some peculiar action of the nervous system, so to change the character of the lacteal fluid as to make it unfit for the nourishment of the infant, and in some cases to render it absolutely poisonous. Carpenter * records a case of this character in which immediate death of the child followed the taking of the breast of a nursing mother who had sufiered great mental agitation. These occurrences have been explained in part by the discovery of Dr. Victor C. Vaughn, of Michigan University, who found that under certain fermentative changes a poisonous ptomaine, which he has termed tyrotoxicon, is formed in milk and cheese, and also in ice- cream. * Physiology, 1862, p. 742. 600 OPERATIVE DENTISTRY. INSTRUMENTS USED IN THE OPERATION OF EXTRACTING. An examination of the mouth and of the tooth to be removed should always be made before any steps are taken in the operation. For this purpose a mouth-mirror (Fig. 660) and a curved probe or explorer are necessary. Fig. 660. Mouth-mirror. Gum-lancets (Fig, 661) are employed in some cases to dissect the gum from around the cervix of the tooth prior to the adjustment of the extract- ing instrument. These cases are represented by the third molars, teeth which stand alone, and roots which are buried more or less completely Fig. 661. Gum-lancet. by overlying gum-tissue. In all other cases the use of the gum-lancet is rarely indicated, provided the beaks of the forceps are made sharp, so that they will cut their way through the margin of the gum as the in- strument is pushed towards the alveolar border. Fig. 662. Curved scissors (Fig. 662) are also necessary to a complete extracting outfit, and should be at hand for severing any portion of gum-tissue that might be found adherent to the cervix of the tooth. EXTRACTION OF TEETH. gQl Month-props and gags (Figs. 663 and 664) should be employed when a general anesthetic is administered, the object being to obviate the neL sity of having to open the mouth forcibly before the tooth can be reached and to conserve valuable time, which is an exceedingly important con- sideration when nitrous oxide gas is used. (See also those on page 592.) ^^«- 6^3. Fia. 664. Mouth-prop. Mason's gag. ../^Vr' ''i^^'' ^^^'''' ^^^ '^^'^^^ ^^ ^«^^^^^d ^ith rubber tubing, to prevent them from slipping or causing injury to the teeth. The jaws of the^ gag are separated by turning the milled nut downward. The curve of the jaws of the instrument is such that the handles extend backward Fig. 665. Warren's screw-gag. under the lobe of the ear, and are therefore entirely out of the way of the operator. "^ In adjusting the gag, its jaws should be placed between the molar teeth upon the side of the mouth opposite to that where the operation is to be performed. The screw-gag (Fig. 665) is an exceedingly useful instrument for opening Fro. 666. Tobolt's laryngeal forceps. or extending the jaws in cases of trismus caused by inflammation and swelling. Its application needs no explanation. A laryngeal forceps (Fig. 666) is also a necessary part of a complete extraction outfit. In case a tooth or a fragment of one should fall into 602 OPEEATIVE DENTISTRY. the fauces beyond the reach of the finger, this instrument would be most valuable for its removal. The instruments which are employed for the extraction of teeth are the turnkey, forceps, and elevators. Turnkey.— The turnkey, which for many years was the only instrument employed in the extraction of teeth, has at the present time been almost entirely discarded. It is, however, a very serviceable instrument in certain cases where the crown of a molar Fig. 667. ]2as been broken away by caries or accident to a point beneath the gum, upon the buccal or lingual side only, while the remaining portion is strong. Such cases offer great difficulties to their extrac- tion with the forceps, which either slip off or carry away the remain- ing portion of the crown, while it is often impossible to remove them with an elevator. The ap- plication of the turnkey (Fig. 667) to such teeth converts a difficult operation into a simple one. This is accomplished by placing the fulcrum upon the gum upon the side of the tooth which has been broken away, and the claw upon the opposite side of the tooth at the margin of the gum. This permits a proper direction of the force applied, and admits of an easy and natural removal of the tooth. Forceps. — In these days of aseptic surgery all forceps should be made in such a manner that they may be taken apart, as this gives a better opportunity for thorough sterilization. Fig. 668 shows an instrument of this character, the joint of which is very simple in construction, strong, and easily cleansed. Fig. 668. Turnkey. Aseptic forceps. The heaks of the forceps should be of such shape as to fit as large a sur- face as possible of the cervix of the tooth for which they are constructed, without pressing too hard upon the cervix or t\iQ crown. If the pressure comes too hard upon the crown, it is liable to be crushed ; while if the EXTRACTION OF TEETH. 603 curve of the beaks is so great that the terminal edges grip the cervix only, there is danger of fracturing the tooth at this point. This quite often hap- pens with the use of lower molar forceps that are improperly constructed. The terminal edges of the beaks should be made sharp, so that when they are crowded against the cervical border of the gum they will cut their way, and thus avoid the necessity of using the gum-lancet. The handles of all forceps should be serrated in such a manner that when gripped by the hand they will not slip. This is very important, for if any considerable pressure is i^laced upon the handles to keep them from slipping, there is danger of crushing the crown or cutting it off. The curves of the beaks and the handles must be of such form as to permit a proper adjustment of the beaks to the teeth to be extracted, while the handles should not impinge upon the anterior teeth of the opposite jaw, and should allow the force which is applied to be made in a direct line with the long axis of the tooth, or, in other words, in a line with the general direction of the roots. Elevators. — -These instruments are devised for the extraction of roots which are too frail to withstand the grip of the forceps or the pressure of Fig. 669. I' Elevators. the turnkey. In applying these, instruments the grooved face is adjusted to the surface of the tooth, and the blade carried downward to the alveolar process. Force is then exerted in a direction to lift the tooth from the alveolus. Fig. 669 shows several forms of elevators, all of which are useful, and should be found in every complete extracting outfit. Fig. 670. Dental screw. The dental screw (Fig. 670) is also a valuable instrument for tne removal of very frail roots in which caries has followed the pulp-canal and converted the root into a mere shell. This instrument is applied by screwing it into the cavity in the root until the thread takes a firm hold upon the dentin, when the root is easily lifted from its alveolus. 604 OPERATIVE DENTISTRY. THE SELECTION OF THE PROPER INSTRUMENTS FOR THE EXTRACTION OF THE VARIOUS CLASSES OF TEETH, THEIR PROPER ADJUSTMENT, AND THE KIND AND DIRECTION OF THE FORCE APPLIED. The teeth, from the stand-point of their proper extraction, may be divided into seven classes, according to the number and the anatomic form of their roots. The first class includes the superior central and lateral incisors, which have single, cone-shaped roots. The second class embraces the inferior central and lateral incisors, which have single, considerably flattened, cone-shaped roots. The third class comprises the superior and inferior cuspids, which, have single, very long, slightly flattened, cone-shaped roots. The fourth class includes the superior and inferior bicuspids, which have single, sometimes bifurcated, flattened, cone-shaped roots. The fifth class comprises the superior first and second molars, which, have three cone-shaped roots, — two buccal and one lingual. The sixth class embraces the inferior first and second molars, with two flattened, cone-shaped roots, — one mesial and one distal. The seventh class includes the superior and inferior third molars, which may have either a single cone-shaped root that curves backward or multiple roots. Fig. 671 shows the relation of the teeth to the alveolar process, and Fig. 672 shows the form and number of the roots of the teeth and their deeper relations to the alveolar processes. First Class. — In the extraction of teeth of thejirst class, the operator should stand upon the right side of the patient, who is seated in the operating- chair with the head thrown well back and supported between the chest and the left arm of the operator, and the lips shielded from injury by the fingers of his left hand. The forceps selected for the opera- tion should be straight, as shown in Figs. 673 and 674. The instrument shown in Fig. 673 is intended for the extraction of the superior central Fig. 673. Superior central incisor forceps. incisors, but it is equally adapted for the extraction of the superior cuspids. The forceps is adjusted to the tooth by grasping the handles loosely with the right hand, with the little finger between the handles. This gives control of the opening and closing of the jaws of the instrument, and permits the regulation of the force applied in grasping the tooth, which is of considerable importance in extracting a tooth much weakened by caries. The beaks of the forceps are then crowded well beyond the cervix of the Flii. 071. Fig. 672. EXTRACTION OF TEETH oUo tooth, and in so doinsr cut their w«v in fii^ ^^ ^ ■, . rotation fail to dislod<.e the tooth n I 7 . .^^*^ ''"'^^"^- ^'^^^^^^ K. ■ ^ ^r '^' ^^*'^ ^^^ '^'^oth, a forward and backward movement-, nm^ be given to the forceps, combined with rotation. movement may Fig. 674. Superior lateral incisor forceps. of th—^riT" r'' """' ""''' """^^' ""'P'^y'^'i '<" '^^ •'^action 01 the superioi lateral mcisors. The adjustment of the instrument and he apphoataoo of force are the same a. for the extraction of the supc'or central mcisors. »upeuor y. ^f/°^^^^l^^s— In extracting teeth of the second ckm, the operator should stand upon the right side of and a little behind the patient, "hose Fig. 675. Inferior incisor forceps, full curve. lower jaw is supported with his left hand, and the lips shielded with the hngers of the same hand. The forceps shown in Figs. 675 and 676 are most admirably adapted for the removal of the inferior central and lateral Fig. 676. Inferior incisor forceps, narrow beaks, full curve. incisors, while the hawk-bill forceps shown in Fig. 677, and the half-curved, narrow-beak forceps shown in Fig. 678, are useful in removing very narrow inferior central incisors and other inferior teeth with single roots which, by reason of an irregularity in their position, prevent the application of 6U6 OPERATIVE DENTISTRY. the broader-beaked instruments ordinarily used for their extraction. The direction of the force which should be applied in the removal of these Fig. 677. Inferior incisor forceps, hawk-bill. Fig. 678. Inferior incisor forceps, half curve. teeth w, forward and backward, to break up their attachments to the alveo- lus, and in an upward direction to lift them out. Third Class. — The i30sitions of the patient and the operator and the means of supporting the head and protecting the lips are the same as described for the first class. The forceps best adapted to the extraction of Fig. 679. Superior cuspid forceps. Fig. 680. Superior cuspid and bicuspid forceps. the superior cuspids are those shown in Figs. 679, 680, and 681. Inasmuch as these teeth have the longest roots and are the most firmly fixed in their alveoli of all the teeth, it requires more skill and strength to extract them than any other teeth in the mouth, and consequently the instruments EXTEACTION OF TEETH. 607 used for this purpose must be very strong. In adjusting the forceps, the beaks should be forced upward and beyond the cervix as far as the border of the alveolus, the tooth firmly gripped, and force applied by a combined rotary^ forward, and backward movement. The attachments of the tooth are thus broken up, and it is removed from its alveolus. The position of the patient for the extraction of the inferior cuspids should be as nearly upright as possible, with the chin well down upon the chest, while the position of the operator should be upon the right side and Fig. 681. Superior cuspid and bicuspid forceps. Fig. 682. Inferior cuspid and bicuspid forceps. Fig. 683. Inferior cuspid and bicuspid forceps, full curve. slightly behind the patient. The chair should be low enough to give him full opportunity to apply force in an upward direction, while at the same time it is applied in a forward and backward direction. The roots of these teeth are so much flattened laterally that rotation cannot be suc- cessfully employed. The forceps best adapted for the extraction of these teeth are shown in Figs. 682 and 683. Fourth Class.— The forceps which are best adapted for the extraction of the superior bicuspids are the same as those used for the removal of the superior cuspids. The positions of the patient and the operator, the support of the head^ and the protection of the lips are the same as described for the removal of 608 OPERATIVE DENTISTRY. teeth of the first class. The instrument is adjusted by grasping the tooth at the cervix and crowding the beaks upward to the border of the alveolus, then firmly grij)ping the handles of the forceps and applying force for extraction in a combined /orwar^, backward, and downward direction. Fig. 684. Inferior bicuspid forceps, half curve. In extracting the inferior Mcuspids the positions of the patient and operator, the position of the chair, and the protection of the lips are the same as described for the extraction of the inferior cuspids. The instru- FiG. 685. Inferior bicuspid forceps, full curve. ments best adapted for the extraction of these teeth are shown in Figs. 684 and 685. The application of force should be in a combined forward, hack- ward, and upward direction. Fifth Class. — The superior first and second molars, by reason of the number and form of their roots, often require considerable strength to dislodge them from their alveoli. The beaks of the forceps which are used for the extraction of these teeth require to be especially made to conform to the shape^of the teeth at the cervix. The outer or buccal beak of the forceps is constructed with a projecting point in the centre, which fits into the sulcus formed by the bifurcation of the buccal roots, while the inner beak is made plain, to fit the convexity of the lingual surface of the lingual (palatal) root. These instruments are usually made in pairs, right and left, to suit the form of the teeth upon opposite sides of the mouth. The jaws and handles should be so curved as to make it possible to grasp these teeth and not have the handles come in contact with the corner of the mouth or the lips. Fig. 686 shows the form of these forceps. An- other form of forceps is that shown in Fig. 687. These instruments are bayonet-shaped, and have the beaks like those just described, one adapted for the teeth of the right side, the other for the left. The bayonet form given to these instruments makes them very valuable for the extraction of these teeth when the oral commissure is very small. EXTRACTION OF TEETH. 609 In adjusting either of these instruments to the tooth the beaks are made to grasp the tooth at the cervix, the pointed beak being inserted between the buccal roots, and the instrument forced upward to the border of the alveolus. The handles are then firmly gripped, and the Fig. 686. Fig. 687. Right. Left. Superior first and second molar forceps. Harris.) (Dr. Right. Left. Superior first and second molar forceps (bayonet shape). tooth rocked by a backward and forward movement until it is loosened in its alveoli, when force may be applied in a downward direction, and the tooth dislodged. Sixth Class.— The inferior first and second molars have but two roots, and do not, therefore, as a rule, require so much force to extract them as do Fig. 688. Inferior first and second molar forceps (universal), either side. (Dr. Harris.) the superior molars. The beaks of the forceps which are used for the ex- traction of these teeth are each made with a projecting point which fits 39 610 OPERATIVE DENTISTRY. into the buccal and lingual sulci formed by tbe bifurcation of the root. The jaws and handles of the forceps are also curved in such a manner as to permit the tooth to be grasped while the handles remain clear of the lips and of the corner of the mouth. Fig. 688 shows an instrument Fig. 689. Inferior right first and second molar forceps. Fig. 690. Inferior left first and second molar forceps. Fig. 691. Inferior universal first and second molar forceps. (Dr. Hutchinson.) Fig. 692. Inferior universal cow-horn forceps, first and second molars. which is adapted for use ux)on either side of the mouth, while in Figs. 689 and 690 are seen forceps made in right and left forms. Fig. 691 shows another form of universal lower molar forceps, the invention of Dr. Hutchinson, while Fig. 692 illustrates a universal cow- horn lower molar forceps. These are also made for the right and left sides (Figs. 693 and 694). EXTRACTION OF TEETH. 611 The position of the patient, that of the operator, and the method of protecting the lips are the same as in the extraction of the inferior cuspids and bicuspids. Fig. 693. Inferior left first and second molar, cow-horn forceps. In adjusting the forceps care must be taken to see that the points of the beaks are inserted into the buccal and lingual sulci formed by the bifurcation of the roots. The application of force should be a forward and backward Fig, 694. Inferior right first and second molar, cow-horn forceps. rocking movement until the tooth is loosened in its alveolus, when the tooth should be removed by traction upivard. Seventh Class. — The superior third molars, by reason of their position and the usual backward curvature of their roots, are often very difficult to extract. When the root, however, is straight, their extraction is a very simple matter by the use of bayonet-shaped forceps having simple beaks made to fit the convexity of the root upon the buccal and lingual surfaces. Fig. 695 shows such an instrument designed for use upon either the right Fig. 695. Bayonet-shaped superior third molar forceps (universal). or the left side of the mouth. The positions of the patient and the operator and the application of force are the same as for the extraction of the other superior molar teeth. Sometimes these teeth are large and have bifurcated roots. Under such circumstances the ordinary superior molar forceps should be employed for their extraction. 612 OPERATIVE DENTISTRY. When the roots of these teeth curve backward the ordinary forceps nsed for the extraction of the third molars will not dislodge them. Special forceps are then called into use. To meet these requirements the late Dr. Physick invented the forceps shown in Fig. 696. The jaws of this instru- ment represent two inclined planes looking towards each other. The in- strument is designed to act as a double wedge when placed between two Fig. 696. Superior third molar forceps. (Dr. Physick.) resisting bodies and force is applied by closing the handles. In the ex- traction of a superior third molar the jaws of the forceps are opened and the edges placed between the approximating surfaces of the second and third molars. The handles of the forceps are then closed and depressed, 01' rather carried towards the morsal surfaces of the superior teeth : the Fig. 697. Superior third molar, extracting, separating, and excising forceps. (Dr. Stelhvagen.) double wedge of the jaws thus starts the tooth from its alveolus and the depression of the handles carries the crown backward, dislodging it from its alveolus. Figs. 697 and 698 represent instruments designed by Dr. Stellwagen for the combined purpose of extracting superior and inferior third molars and excising and separating roots. The principle involved in their application is the same as in the Physick forceps. Inferior third molar, extracting, separating, and excising forceps. (Dr. Stellwagen.) The inferior third molars have usually single roots which curve back- ward, but occasionally the roots are multiple. Under these circumstances they can usually be extracted with the forceps shown in Fig. 699, but EXTRACTION OF TEETH. 613 when the root is curved it becomes necessary to employ the Physick or Stellwagen forceps. The instrument is applied as for the removal of the superior third molars, and the handles are closed and depressed. This starts the tooth from its alveolus, tips it backward, and dislodges it. Care must always be exercised in the use of these forceps not to injure the tooth in front which acts as the fulcrum. If these instruments are carelessly Fig. 699. Inferior third molar forceps. handled there is danger of fracturing the enamel, thus preparing the way for the establishment of caries in the injured tooth. Extraction of the Roots of Teeth. — For the extraction of the roots of teeth specially devised forceps are generally employed : these have usually thin, narrow beaks that can be insinuated between the gum and the root. Fig. 700. Screw-forceps. (Dr. C. H. Dubs.) For the extraction of the roots of the six superior anterior teeth which are so decayed as to present thin, frail walls the Dubs screw-forceps (Fig. 700) and the Hullihen screw-forceps (Fig. 701) are the best. These in- struments combine the dental screw with the narrow-beaked forceps. Fig. 701. Screw-forceps. (Dr. S. P. Hullihen.) To adjust the instrument to the root the conical screw is first set into the pulp cavity. If much softened dentin is present this should first be removed and the screw so set that it takes hold upon the sound dentin. The socket between the jaws of the forceps is then placed over the shaft of 614 OPERATIVE DENTISTRY. the screw, and the beaks of the instrument are insinuated between the gum and the root and carried down to the alveolus. The handles are then gripped with just sufficient force to prevent the instrument from slipping, and the root is rotated to the right,— the direction in which the screw is get, — and the tooth is dislodged from its alveolus. Fig. 702. Superior anterior root forceps. Fig. 703. Superior bicuspid and molar root forceps, half-curve. Fig. 704. Superior bicuspid and molar root forceps, bayonet shape. (Dr. B. F. Arrington. Fig. 705. Superior root forceps, bayonet shape. (Dr, Ambler Tees.) Fig. 702 represents a straight root forceps designed for the extraction of the roots of the six superior anterior teeth, which can be used in all cases where the root is not so badly decayed as to be liable to crush under the pressure necessary to keep the instrument from slipping during the extraction. For the extraction of the superior bicuspids, the half-curved forceps represented in Fig. 703 will be found most admirable instruments. EXTRACTION OF TEETH. 615 For the extraction of the roots of the superior molars there is no better instrument than the bayonet-shaped root forceps shown in Figs. 704 and 705. Great care should be exercised in the extraction of the roots of the su- perior bicuspids and molars not to force them upward into the antrum of Highmore, as under such circumstances an extended surgical operation becomes necessary for their removal, involving the exsectiou of »■ con- siderable portion of the floor of the sinus. Fig. 706. Inferior incisor, cuspid, and bicuspid root forceps, full curve. For the extraction of the roots of the six inferior anterior teeth and the bicuspids, the full-curved lower-root forceps shown in Figs. 706 and Fig. 707. Inferior root forceps, full curve. (Dr. Ambler Tees.) 707 will be found most useful. The points of the beaks in the "Tees" forceps are made thin so that it is possible to insinuate them between the root and the gum. Fig. 708. •^WMtS^i^'si^.'J.'.'NVsV-.'aw Superior alveolar root forceps, bayonet shape, with beaks of Dr. Kell's pattern. In the extraction of roots in the superior jaw that are buried in the tissues, the "alveolar" forceps shown in Fig. 708 is most admirably adapted. When using this instrument the gum should be incised upon the labial and lingual surfaces in a line corresponding to the long axis of the root, and the edges of the gum lifted from the alveolar process upon both 616 OPERATIVE DENTI-.TRY. sides of the incisions. The beaks of the forceps may now be insinuated between the gum and the alveolar process, and by a quick, firm pressure upon the handles, the alveolar process is cut through and the root removed. Fig. 709. Deciduous inferior universal forceps. (Dr, M. H. Cryer.) In the extraction of the roots of lower molars the forceps shown in Fig. 709 is most admirably adapted, the beaks being long, thin, and narrow. Fig. 710. Inferior alveolar root forceps. (Dr. J. D. Thomas.) The ^'alveolar" forceps of Dr. Thomas shown in Fig. 710 is a very valu- able instrument for removing such roots as are broken off below the gum. Fig. 711. Deciduous superior anterior and root forceps. The forceps which are used for the extraction of the deciduous teeth should be much smaller and lighter than those employed for the extraction Fig. 712. Deciduous superior molar forceps. of the permanent teeth. Three pairs are sufficient for all purposes. Fig. 711 is for the extraction of the six superior anterior teeth and roots, and Fig 715. ^n 1 1 ^^ 1 ■ 1 1 f ^^B "1 u 1 1 L V^Bi . •'■>^- ■ ^^^^ 1 1 ^ ^^^^^^H M 1 1 L^H iJ Fig. 716. Fig. 717.— After Dr. M. H. Cryer. Fig. 718.— After Dr. M. H. Cryer. Fig. 719.— After Dr. M. H. Cryer. Fig. 720.— After Dr. M. H. Cryer. YiG, 721.— After Dr. M. H. Cryer. Fig. 722. — Skiagraph showing misplaced superior cuspid tooth. EXTEACTIOX OF TEETH. 617 Fig. 712 for the superior molars. Fig. 713 is used for the extraction of the six inferior anterior teeth and for the inferior molars. The '"universal" root forceps of Dr. M. H. Cryer (Fig. 714j are also admirable instruments for the extraction of children's teeth. Fig. 713. Deciduous inferior anterior and molar forceps. Fig. 714. Deciduous and superior universal root forceps. (Dr. M. H. Oyer.) DIFFICULTIES. C03IPLICATIOXS, AND ACCLDEXTS. Anomalous Teeth. — The accompanying illustrations (Figs. 715 and 716) represent some of the more common deformities of the teeth. Figs. 717, 718, 719, 720, and 721, which are kindly loaned to the ^vriter by Dr. ]M. H. Cryer, show some of the more common malpositions of the teeth which complicate the operation of extraction, and often render it extremely difficult and sometimes hazardous. Fig. 722 is a skiagraph showing a misplaced superior cuspid. The cases which present the greatest difficulties are the teeth having sharply curved roots, hypercementosed roots, and teeth which are mis- placed and impacted in the jaws, particularly impacted third molars. Teeth having curved or hypercementosed roots offer great resistance to the force applied for their extraction. In the former the curved end of the root is often fractured and left in its alveolus, while in the latter the alveolar process is usually fractured, the external plate giving way on a line with the alveoli, in the endeavor to remove the tooth. The former accident is, however, of small moment, and the fractured portion of the root may be allowed to remain, as it very rarely causes any serious after-trouble. The fracture of the alveolar plate is more serious, and if neglected or improperly treated may result in necrosis. If, however, the fractured parts are brought into close apposition by squeezing them together with the thumb and index finger, and the alveolus frequently irrigated with antiseptic solutions, union will take place and little or no inflammation or soreness will result : but if, on the other hand, the fractured parts are allowed to remain separated, and no attention is paid to antiseptic treat- ment, osteitis and necrosis are liable to occur. 618 OPERATIVE DENTISTRY. Fig. 723. The most difficult teeth to extract are the imj)acted third molars, which lie more or less horizontally iu the jaw and impinge upon the distal sur- face of the crown or the root of the second molar, as shown in Fig. 723. This condition of impaction occurs most often in the lower jaw. When the crown of the inferior third molar is tilted forward so that it impinges upon the distal surface of the second molar near the cervix or lower down upon the root, further progress in the eruption of the third molar is arrested, and irritation and inflammation are liable to supervene, making it necessary to ex- tract the tooth. In order to accomplish the removal of the impacted tooth, it becomes neces- sary to cut away with corundum disks a con- siderable portion of the mesial cusps of the third molar. After this has been done the tooth may be grasped with the forceps shown in Fig. 724 and the tooth dislodged from its alveolus. Or it may be dislodged with the Physick or Stellwagen ' ^ wisdom-tooth" forceps (Fig. 725). Fig. 724. Inferior left second and third molars as they were located in the jaw. If, however, the third molar has not erupted or only shows a very small portion of the crown through the gum, and the tooth occupies a hori- zontal position in the jaw, two courses only can be suggested for its removal. Fig. 725. Physick forceps. The first is to remove the second molar, as this makes it possible to reach the third molar and extract it. The second is to dissect the gum from over the impacted tooth, chisel or bur away the bone overlying it, and then lift it from its bed with an elevator or Physick forceps. Operations of this magnitude should, of course, be made under a gen- eral anaesthetic, preferably ether, as nitrous oxide anaesthesia would not last long enough to permit the operation to be performed painlessly. EXTRACTION OP TEETH. 619 Other teeth than the third molars are sometimes impacted in the jaws, and require surgical operations for their removal. Those which are most commonly misplaced are the superior cuspids (Fig. 721), laterals, and bi- cuspids, and the inferior bicuspids and cuspids, their relative frequency, according to the experience of the writer, being in the order named. A good general rule to be followed in operations for the removal of impacted teeth is never to sacrifice any other tooth if it can possibly be avoided. Fractures of the Teeth. — In the extraction of teeth that are badly decayed, and in those which by reason of abnormalities in form or position present great difficulties in their removal, fractures of the crown are very liable to occur. Under such circumstances the roots should be immediately removed with instruments suited to the individual case. Sometimes, how- ever, the fracture occurs at the alveolar margin or even lower down, making the removal of the root an exceedingly difficult task, except by the subalveolar method previously described. For this reason the alveolar forceps shown in Figs. 708 and 710 should be found in every complete extracting-case. If the tooth which has been fractured has double or multiple roots, it often becomes necessary to divide them with Stellwagen excising forceps, and extract each root separately. When a tooth is extracted, fractured or crushed, great care should be taken to prevent the tooth or the fragments slipjjing from the jaws of the forceps and falling into the fauces, and becoming arrested at the entrance of the larynx by engaging in the rima glottidis, or, passing downward, becoming lodged in the trachea or one of the bronchi (more often the right), thus preventing or impeding the admission of air to the lungs and causing spasmodic coughing, dyspnoea, and the more serious symptoms of asphyxia. Whenever a foreign substance falls into the fauces the body of the patient should immediately be thrown forward, and the index-finger passed into the mouth and swept around the fauces, in the hope of removing it. Failing in this, the patient's body should be inverted, and while in this position the back vigorously slapped with the flat of the hand. If, how- ever, the foreign body has passed beyond the reach of the fingers, the laryngeal forceps may be employed to reach it, and this may often be done if it has not passed beyond the rima glottidis. If the foreign body has en- tered the trachea or become lodged in a bronchus, an immediate trache- otomy is the only means of relief. Cases of this character may prove imme- diately fatal ; while, upon the other hand, if the fragment of tooth is small, and has passed into a bronchus, it may give rise to no immediate symp- toms, but later the patient may be seized with violent fits of coughing, dyspnoea, bloody expectoration, and finally collapse of the lung. Miller records a case of suppuration and gangrene of the lung due to the presence of a fragment of a decayed tooth. Impaction of a tooth or a fragment of a tooth or other foreign body in the oesophagus or the pyloric orifice of the stomach sometimes occurs, and may give rise in the former to symptoms of dysphagia, and in the latter to gastric dilatation and ulceration. The treatment of these cases belongs to the domain of general surgery. 620 OPERATIVE DENTISTRY. Fractures of the Alveolar Process. — Fractures of tlie alveolar pro- cess are frequently the result of the extraction of the teeth. This accident most often occurs in connection with the superior and inferior cuspids and the superior molars. Teeth which stand alone are the most liable to this accident, although it may occur in connection with the extraction of any tooth if the process is thin, or the operation is roughly or unskilfully iDcrformed, or the roots are malformed, abnormally large, or, as in the molars, widely sj)read. Sometimes the attachment of the alveolar process is so firm that the fractured part comes away with the tooth. This makes an ugly wound in the gum, which may require two or three stitches to bring it together. In the treatment of the other forms of fracture of the alveolar process the simple adjustment of the fractured parts to their normal position and the use of antiseptic solutions is usually all that is required. Osteitis. — Inflammation of the alveolar process is a frequent sequel of the extraction of a tooth in which the gums and process have been bruised and lacerated. This most frequently occurs in those cases where the tooth has been fractured some distance beneath the margin of the gum, and re- peated unsuccessful attempts have been made to remove it. The disease is attended with great pain, tenderness, and swelling of the surrounding tissues, suppuration, and sometimes sloughing of the soft tis- sues and death of the bone. The treatment consists in the free use of antiseptic and stimulating lotions, and anodynes to control the pain. Gangrene and Necrosis. — These conditions frequently follow the unskilful extraction of the teeth, and are the result of crushing the soft tissues in the one case, and of fractures, injuries which cut off the circula- tion, or inflammation in the other. The treatment consists in removing all dead or gangrenous soft tissue with scissors or knife, washing the parts with hydrogen dioxide to remove the pus, and following this with suitable antiseptic lotions. ^Necrosed bone should not be disturbed until separation has taken place between the dead and the living portions. Meddlesome treatment only aggravates the inflammatory process, and often causes an extension of the disease far beyond the limits which were previously involved. The only treatment to be recommended is that comjprehended under the term anti- septic until the sequestrum has formed, when it should be immediately removed, and the parts assisted in the healing process by thorough cleanli- ness and the use of stimulating and antiseptic solutions. Hemorrhage. — Hemorrhage of a severe and continuous type often seriously complicates the operation of tooth extraction in those individuals who are subjects of the hemorrhagic diathesis, and quite a number of cases are on record in which the hemorrhage has proved fatal after every effort had been made to arrest it. Hemorrhage may be primary, recurrent, or secondary. Primary hemorrhage is that which occurs from the alveolus immediately after the tooth has been extracted, and usually does not continue for more than half an hour. Sometimes, however, the primary hemorrhage is pro- EXTRACTION OF TEETH. 621 fuse, and calls for treatment for its control. The use of cold water or ice- water, or water as hot as can be borne in the mouth, to which a few drops of tincture of myrrh or aromatic sulphuric acid have been added, will gen- erally be sufficient to arrest it. Becurrent or secondary hemorrhage is that which follows a few hours aft-er the primary hemorrhage has ceased. This form of hemorrhage usually comes on in the night following the day upon which the tooth was extracted, or following the sloughing of soft tissue whose vitality had been destroyed by the traumatism or by the application of escharotic styptics. Sometimes the hemorrhage seems to be confined to the artery which supplied the tooth, the blood welling up from the apex of the alveolus ; in other cases the whole inner surface of the alveolus seems to take part in the hemorrhage ; while in others it may be confined to the gum. In the more severe cases in which there is a marked history of the hemorrhagic diathesis, the blood is found to flow not only from the dental artery, but from the inner walls of the alveolus and the gums as well, the bleeding in some cases being so profuse that the patient may lose from a pint to a quart or more of blood in a few hours, causing great weakness and con- siderable alarm and anxiety upon the part of the patient and the friends, In examining the mouth in a case of secondary hemorrhage, care should be taken to locate the exact source of the bleeding, whether it is from the gum, the inner wall of the alveolus, or the dental artery. If the hemorrhage comes from the gum, the bleeding point may be compressed with the haemostatic forceps, or any little vessel picked up and torsion applied. If this does not arrest the bleeding, a compress may be made of warmed gutta-percha or modelling compound, pressed over the part, and when cooled removed, lined with lint or cotton, saturated with a solution of tannic acid in glycerol, and returned to the mouth, and com- pression made by closing the jaws upon the compress, and binding them together with a four- tailed bandage. When the hemorrhage is from the socket or the dental artery, the case should be treated by plugging the alveolus. This may be done by forming a plug to fit the alveolus from warmed wax or modelling compound, made in the form of a cone, a little longer and larger than the tooth which had been removed, and pressing it firmly into the alveolus. The large end of the plug should rise a little above the crowns of the adjacent teeth, so that when the jaws are closed pressure will be brought to bear upon the plug. When cooled it can be removed, the alveolus cleared of blood-clots and washed with ice-water charged with a suitable antiseptic, and the plug returned to the alve- olus after it has been rolled in tannic acid or dipped in the tannic acid and glycerol solution. The jaws should then be closed ujdou the plug and maintained in that position by the adjustment of the four-tailed bandage. The writer considers this method very much better from the aseptic stand-point than the old method of packing the alveolus with cotton, lint, or strips of bandage, as the liability to septic infection and suppurative inflammation is greatly reduced. When the hemorrhage comes from the alveoli of several contiguous 622 OPERATIVE DENTISTRY. teeth, each alveolus should be treated by the method described, and then all may be bound together, while they are in place, by another piece of warmed modelling compound pressed down over the exposed ends of the plugs and moulded to the gums upon the buccal and lingual surfaces, and when nearly cooled the jaws may be closed upon it sufficiently to take an impression of the opposing teeth. After the mass has thoroughly cooled it may be removed altogether, the plugs treated as just described, and the whole returned to its place and retained in position by the closed jaws and the four-tailed bandage. If there is time to do so, and the facilities are at hand, a metal or vul- canite splint may be constructed from an impression taken of the parts. When this method is pursued, the alveoli should be plugged with modelling comi^ound and the splint used to force the plugs into place and produce compression upon the gums. A few cases are on record in which, after arresting the hemorrhage from the alveolus, oozing of blood from the mucous surface of the gums occurred, as is sometimes seen in scorbutus and purpura Jicemorrliagica. In these cases it becomes necessary to secure compression over a con- siderable area of the gums, and this can best be accomplished by the metal splint just described. Before applying the splint it should be lined with cotton or lint, and saturated with a non-irritating styptic. The use of escharotic styi^tics, like the perchloride of iron, nitric acid, and chromic acid, should never be permitted, as they cause sloughing of the soft tissues and secondary hemorrhage, which is more difficult to control than the former condition, by reason of the greater surface involved as a result of the escharotic action of the remedy. After the compresses have been applied, the patient should be instructed to keep as quiet as possible, maintain the sitting posture, and avoid all hot fluids and stimulants. Liquid diet should be ordered, — milk, beef extracts, broths, and soups. In those cases in which there has been great loss of blood, stimulants may be administered and the body kept warm. The hot foot-bath is some- times serviceable in diverting the blood to the lower extremities and re- lieving arterial tension in the upper part of the body. To the constitutional remedies which have been mentioned as useful in controlling the tendency to hemorrhage in those persons having the hemorrhagic diathesis, — viz., gallic acid combined with opium, and the fluid extract of ergot, — the perchloride of iron may be added, — R Liq. ferri perchlor. , m. x ; Aq. destilL, f^j. M. To be taken every two hours. Fatal syncope has been known to follow the extraction of a tooth in cases in which there was no functional or organic disease of the heart. Tomes calls attention to two such cases that have been placed on record. A similar case came under the knowledge of the writer, as occurring in EXTRACTION OF TEETH. 623 the practice of a friend. In this case, however, there was fatty degenera- tion of the heart, as shown by the post-mortem examination. The patient was a lady about sixty years of age, and was apparently in good health. The dentist seated her in the chair preparatory to the operation, and turned to his case to select the instrument, when she fainted and could not be resuscitated, death occurring almost instantaneously. INDEX. Abbot on resorption of teeth, 76 Abrasion, causes of, 371 definition of, 368, 371 treatment of, 372 Abscess, dento-alveolar, see Dento-alveolar abscess Acids and alkalies, influence of, on growth of bacteria, 90, 91 Albuminoids and mouth bacteria in caries, 151 Alcohol, use of, in hypersensitive dentin, 190 Alexander's method of making gold inlays, 347, 348 Alloys, composition of, 314-319 making of, 319, 320 Allport's pyorrhoea alveolaris instruments, 547 Aluminum, use of, in alloys, 314, 315 Alveolar abscess associated with deciduous teeth, 488 chronic, 485 treatment of, 486, 487 Amalgam-carriers, 326 Amalgam, definition of, 296 fillings, finishing of, 330 indications for use of, 321, 322 -instruments, 326, 327 manipulation of, 325-327 nature and properties of, 298 setting of, 298, 299 wafering of, 327 Amalgams, annealing of, 309, 310 color of, 312 composition of, 296, 297 conductivity of, 312, 313 contraction and expansion of, 299-310 flow of, 306 mixing of, 323-325 stability of, 310, 311 washing of, 325 Amelification, 39 Ameloblasts, 32, 34, 35 Ammonia, use of, in treating gold, 256, 257 Anaesthesia, Bon will's method, 216 definition of, 578 electro-cocaine, 207-211 general, 586-594 examination of patient for, 590, 591 Hewitt's method, 589, 590 precautions against accidents, 591, 592 local, 578-586 Letamendi's method, 580, 581 Richardson's method, 579, 580 with chloretone, 584, 585 with cocaine, 581-583 with eucaine, 584 with tropacocaine, 583, 584 use of, in hyiDersensitive dentin, 187, 214-216 Anaesthetic, see Anaesthesia Anatomy, classification, and description of the teeth, 1 Animal fungi (mycetozoa), 85 Anomalous teeth, 617 Anterior teeth, separation of, 175 Antikamnia, use of, in pericementitis, 465 Antimony, use of, in alloys, 314 Approximal cavities, preparation of, 225- 228, 230, 231 Arkansas stones, use of, in formation of margins, 249 Arkovy on action of arsenic upon dental pulp, 426, 427 Arnott on local anaesthesia, 581 Arsenic, physical effects of, on dental pulp 424, 425 use of, in devitalizing pulps, 423, 427- 429 Atropia sulphas, use of, in hypersensitive dentin, 188 Attrition, causes of, 369, 370 definition of, 368 pathology of, 370 treatment of, 370 40 625 626 INDEX. Bacilli, classified, 86, 88, 89 Bacillus, anthrax, 87 buccalis maximus, 93, 97, 99 Bacteria, action of antiseptics on, 169 aerobic, 86 aerogenic, 87 anaerobic, 86 chromogenic, 87 classification of, 86 conditions necessary for growth of, 154 effect of, on integrity of dental tissues, 101, 102 functions of, 87 in caries, 153 influence of heat and moisture on, 91 in mouth, 92, 148 multiplication of, 89, 90, 98 pathogenic, 87, 88, 92 action of, 102 saprogenic, 87, 101 zymogenic, 87, 101 Bacteriology, definition of, 83 Balsam del deserto, use of, 489 Barbed nerve-broaches, 430 Batteries, electric, description of, 200, 201 Bibulous paper, exclusion of moisture by, 178, 179 Bichloride of mercury as an antiseptic, 169 use of, in implantation, 498, 500 in transplantation, 495 Bicuspids, cavities (compound) of, prepa- ration of, 231-233 (simple) on approximal surfaces, preparation of, 227, 228 on exposed surfaces, prepa- ration of, 220-225 inferior, 15, 16 superior, 12-15 Bing's pluggers, 259 Bismuth, use of, in alloys, 315 Black on chronic pulpitis, 415 on erosion, 366 on pathology of pulp hypersemia, 381 on resorption of teeth, 76 on secondary dentin, 422 on suppuration of pulp, 410 Black's method of treating acute alveolar abscesses, 483, 484 one-two-three mixture, 463 Bleaching discolored teeth, 446-458 cataphoric method, 465-458 chlorine method, 451 dioxide methods, 452-455 Bleaching discolored teeth, sulphurous anhydride method, 455 Truman method, 451, 452 preparation of tooth for, 449, 450 Blind abscesses, drainage of, 483 Blood-serum therapy in poisoning from bacteria, 90 Boll on nerve-endings in pulp, 44 Boric acid, use of, in implantation, 499 Brophy's band matrices, 284 Bud fungi, description of, 85 Bunge on analysis of proteids, 447 Burnishers for finishing fillings, 288, 289 Burs, plug-finishing, forms of, 189 Cadmium, use of, in alloys, 315, 316 Calcic deposits upon the teeth, 521 Calcification, definition of, 34 Calcoglobulin, 36, 44 Calcospherites, 32, 35, 51 Callahan's method of enlarging pulp- canals, 436 Cannabis indica, use of, in hypersensitive dentin, 188 Caoutchouc, separating teeth with, 177 Carbohydrates, fermentation of, 101, 102 groups of, 150 in the mouth, 148 Carbolic acid, use of, in devitalizing pulps, 424 in disinfecting cavities, 246 in hypersensitive dentin, 190, 191 Caries, abnormal oral secretions as predis- ing cause of, 123, 124 central, origin of, 140 chemical theory of, 140-143 constitutional predisposing causes of, 124-131 decalcification of, 156, 157 definition of, 115 diagnosis of, 163, 164 diagnostic of inherited syphilis, 129, 130 electro-chemical theory of, 143, 144 etiology of, 123 excision of, 172, 173 expansion of tubuli in, 157-160 forms of, 140 germ theory of, 144 historic facts, 115, 116, 135-148 humoral theory of, 136 immunity in, 154, 155 inflammatory theory of, 136-139 INDEX. 627 Caries, influence of continued fevers on, 130 of exanthemata on, 130 of inherited disease on, 129, 130 irregularities as predisposing cause of, 132, 133 local predisposing causes of, 131-134 of bone, 135 of cementum, 60 of dentin, 153 penetration of, 160 peripheric, origin and forms of, 140 phenomena of, in dentin, 155, 156 pigmentation of, 156, 157 predisposing causes of, 123-134 prevalence of, in present civilization, 118, 119 prognosis of, 164, 165 prophylactic treatment of, 166, 170 putrefaction theory of, 140 silver nitrate in treatment of, 171, 172 stages of, 161, 162 structural defects as predisposing cause of, 131, 1S2 susceptibility in, 154, 155 symptoms of, 162, 163 syphilis, hereditary, and, 129, 130 tables relative to, 121, ]22 theories of, 136 therapeutic treatment of, 171 traumatic injuries as predisposing cause of, 132 varieties of, 161 worm theory of, 139, 140 Carnivora, definition of, 1 Caseation, definition of, 401 Cataphoresis, definition of, 193 resistance of tissues in, 211, 212 substances used in, 196 Cataphoric appliances, 456-458 bleaching method, 455-458 Cavities, classification of, 217, 218 guarding of, with amalgam, 328, 329 margins of, formation of, 248 opening of, 235, 244 preparation of, 212, 234, 235, 354 removal of decay in, 244 retentive shape of, 246-248 Cementification, 35, 53 Cementoblasts, 35 Cement spatulas and mixing-slab, 338 Cementum, 52 caries of, 160 histological composition of, 52 Chappell's pluggers, 265 Chloretone as a local anaesthetic, 584, 585 in hypersensitive dentin, 188 Chloretone in lining cavities, 332 Chlorinated soda as a bleaching agent, 452 Chlorine as a bleaching agent, 451 Chloroform, use of, in hypersensitive den- tin, 216 Chloro-percha, use of, in filling pulp-canals, 442 Cleansing teeth, instructing patients in, 167 Climatic influences predisposing to caries, 126, 127 Cloves, oil of, use of, in disinfecting cavi- ties, 246 in hypersensitive dentin, 190 Cocaine as a local anaesthetic, 581-586 in cataphoresis, 194, 208, 212 in hypersensitive dentin, 188 in phagedenic pericementitis, 577 poisoning, symptoms of, 585, 586 treatment of, 586 Cocci, 85, 86 Conducting cords and tips, electric, 207 Constitutional treatment of primary mor- bid dentition, 70, 71 Copper amalgam, antiseptic action of, 313 as a filling-material, 329, 330 manipulation of, 317, 318 preparation of, 316, 317 electric conductivity of, 202 use of, in alloys, 316 Corundum wheels, forms of, 290 Cotton, exclusion of moisture by, 178, 179 filling pulp-canals with, 440 separation of teeth with, 176 sterilization of, 176 Cushing's pj'orrhoea alveolaris instru- ments, 548 Cuspids, cavities in, compound, prepara- tion of, 229-231 simple approximal, preparation of, 225-227 exposed, preparation of, 218- 220 inferior, 11, 12 superior, 9-11 Custer's electric oven, 352 D Darby-Perry pluggers, 265 Darby's capsicum and sinapin plasters, use of, in pericementitis, 464 Decalcification in caries, 156, 157 Decay, percentage of, in deciduous teeth, 120 in permanent teeth, 120 628 INDEX. Deciduous teeth, 2, 24, 25, 73 extraction of, indications for, 595, 596 exuviation of, 73, 74 formula for, 2 resorption of, 74, 75 retention of, causes of, 74 Dental groove, primary, 29 secondary, 29 ridge, 30 tissues, calcification of, 34 chemical composition of, 54 histology of, 34 Dentin, caries in, 155, 156 chemical composition of, 42 decalcification of, 244-246 definition of, 41, 184 discoloration of, 429, 430 pathology of, 447-449 globules, 47 hypersensitiveness of, 184 causes of, 184, 185 treatment of, 186, 187, 214 anaesthetic, 214-216 chemical, 188-192 palliative, 187, 188 matrix of, 42 papillae of, 30, 31 Dentinal fibres, disorganization of, in caries, 159, 160 fibrils, function of, 44 sheaths, 44 tubuli, 43 tumors, 39 Dentinification, theories of, 35, 48 Dentition, 59 primary, causes of irritation, 65, 66 constitutional treatment of, 70, 71 eruptive process of, 60-62 local symptoms of, 69, 70 morbid, 64 complications arising from, 67, 68 treatment of, constitutional, 70, 71 local, 71 gum-lancing, 71, 72 mortality from, 68, 69 periods of completed root forma- tion of, 64 of eruption of, 59 secondary, symptoms of, 79 Dento-alveolar abscess, causes of, 474-476 chronic, 479 definition of, 474 differential diagnosis of, 480 Dento-alveolar abscess, location of, 477-479 pathology of, 476, 477 prognosis of, 480-482 pus formation in, 477 symptoms and diagnosis of, 479, 480 treatment of, constitutional, 482 local, 482-485 varieties of, 476 Denudation (erosion), definition of, 359 De Trey's solila gold, 269 Diapedesis (exudation), definition of, 398 Dislocation of teeth, 501 Disto-labial cavities, preparation of, 229 Disto-lingual cavities, preparation of, 229, 230 Disto-morsal cavities, preparation of, 231 Donaldson's bristles and pulp-canal cleansers, 435 Dover's powder, use of, in pericementitis, 465 Dynamo-current controllers, 206 E Electric gold annealers, 271 hot-air syringe, 190 mouth-lamp. 111 Electricity, "generation of, 199, 200 induced, classes of, 202 transmission of, 202 units of measurement in, 203, 204 use of, in phagedenic pericementitis, 577 Electrolysis, anodal, 197, 198 cathodal, 198, 199 Elevators for extraction, 603 Elliot's clamp and forceps, 182 Enamel, calcification of, 39, 40 caries of, 152, 153 chemical composition of, 38 -chisels, use of, in opening cavities, 242-244, 249 definition of, 36 -globules, 41 -organ, 30 blood-supply of, 40 invagination of, 31 -prisms, 37 transverse striations of, 37 Endogenous spore formation, 98 Engine-burs, use of, in opening cavities, 241, 242, 249 Epiderm, development of, 27 Epithelial band, 30 cells, 26 INDEX. 629 Epithelial lamina, 30 tissue, evolution of, 26 Erosion of teeth, definition of, 359 etiology of, 360-367 pathology of, 367 treatment of, 367, 368 Eruption of teeth, forces producing, 62 Essential oils, use of, in devitalizing pulps, 424 Ether, administration of, 215, 592-594 as a local anaesthetic, 579, 580 use of, in hypersensitive dentin, 215, 216 Ethyl chloride as a local anaesthetic, 581 Eucaine as a local anaesthetic, 584 Evolution of epithelial tissue, 26 of jaws, 29 of teeth, 30 Examination of teeth, technique of, 112- 114 Excavating in hypersensitive dentin, 186, 187 Excavators, forms of, 226, 245 Excision, effects of, 174 of caries, 172, 173 Explorers, 110 forms of, 111 Extraction of dental roots, 613-617 of teeth, 595-623 conditions unfavorable to, 597-599 fractures of alveolar process in, 617, 620 hemorrhage following, 620-623 indications for, 595-597 instruments used in, 600 of impacted third molars, 618 of inferior central and lateral in- cisors, 605, 606 first and second molars, 609- 611 of superior and inferior bicuspids, 607, 608 cuspids, 606, 607 third molars, 611-613 central and lateral incisors, / 604, 605 first and second molars, 508, 509 Filling compound cavities with gold, 278- 283 materials used in, 251 points to be observed in, 250, 251 simple cavities with gold, 272-278 Fission fungi, 84 Fistula, dento-alveolar, treatment of, 487 Flagg on physical effects of arsenic on pulps, 425, 426 Flagg' s gutta-percha softener and tool- heater, 334 wafering pliers for amalgam, 324 Floss-silk, 112, 167 Forceps, aseptic, 602 for extraction, 604-618 Fractures of alveolar process in extraction. 617, 620 of teeth, classification of, 505 in extraction, 619 union aftef , 507, 508 Gangrena oris, 70 Gangrene, as result of extraction, 620 Gates-Glidden drills, 435 Gauze, exclusion of moisture by, 178, 179 Gingivae (gums), histology of, 58 Gingivitis, definition of, 541 Gnathodynamometer, definition of, 239 Gold, annealing of, 270, 271 as a filling-material, 251 cohesive, description of, 256 foil, description and forms of, 262, 263 introduction of, 263 crystal mat, in filling, 269 preparation of, 268 cylinders, non-cohesive, 258-260 fillings, finishing of, 287, 288 repairing of, 293-295 flow of, under stress, 253, 255 -foil (non-cohesive), method of intro- duction of, 258, 259 properties of, 255-257 use of, in filling pulp-canals, 439 moss fibre, in filling, 269, 270 non-cohesive, description of, 256, 257 -pluggers, 259, 260, 264, 265, 267 ropes and ribbons in filling, 261 strength of, 252 use of, in alloys, 318 Gold-and-platinum foil, 270 Goodsir's theory of evolution of teeth, 28 Gouty pericementitis, 467, 550-567 differential diagnosis of, 469 prognosis of, 469 symptoms and diagnosis of, 468, 469 treatment of, 469 Granulation-tissue defined, 477 Green stains upon the teeth, 521 treatment of, 521 630 INDEX. Guilford's matrix, 284 Gum-retractor, 272 Gums (gingivse), 58 Gutta-percha as a capping for pulps, 333, 418 as a filling-material, 330, 331, 441 as a permanent filling, 333 fillings, finishing of, 336 in filling root-canals, 332, 441 , manipulation of, 335, 336 physical characteristics of, 331, 332 separating teeth with, 177 softening, 333-335 H Heematogenic calcic pericementitis, 550-567 Hsematoidin, 448, 449 Hsemosiderin, 449 Harlan on bleaching teeth, 453 Heated air in treatment of hypersensitive dentin, 189, 190 Hemorrhage following extraction, 620-623 treatment of, 621, 622 from lancing gums, 73 Herbst's burnishers for gold, 264 method of making glass inlays, 351 of packing non-cohesive gold, 261 Heredity, influence of, on caries, 129 Hewitt's method of general anaesthesia, 589, 590 Hill's stopping, 330 How's cervix clamp, 181, 272 inlay burs, 351 thermoscopic heater for gutta-percha, 335 Huber on nerve-endings in pulp, 47 Hutchinson on syphilitic teeth, 129, 130 Hydrochloric acid, use of, in enlarging canals, 436 Hydrogen dioxide as bleaching agent, 452, 453, 456, 457 Hypersemia of pulp, 373, 385 Hypercementosis, causes of, 513, 514 pathology of, 514, 515 symptoms and diagnosis of, 516, 517 treatment of, 517 Hyperplasia, definition of, 401 Hypersensitive dentin, 162, 184 Hypertrophy, definition of, 513 Hypoderm, development of, 27 Immunity, definition of, 103 Implantation, definition of, 496 instruments used in, 498, 499 Implantation, operation of, 498-500 preparation of tooth for, see Trans- plantation prognosis of, 500 requirements for, 497 Implanted teeth, resorption of, 77 Incisors, cavities in, compound, 229-231 simple, 218-220, 225-227 inferior, 8, 9 superior, 4-8 Incremental lines, 48 Infectious diseases, 104 Inflammation, definition of, 397 forms of, 401, 402 physical signs of, 397 tissue changes in, 399-402 Inflammatory phenomena, table of, 402 Inhaler for ether administration, Allis's, 593 Lente's, 593 Inlays, amalgam, 348, 349 definition of, 346 glass, making of, 351, 352 gold, making of, 347 porcelain, cavity prtiparation for, 354 finishing of, 358 manipulation of, 354-358 methods of using, 349-351 taking impression of cavities for, 355, 356 setting of, 357, 358 Inostosis, definition and description of, 515, 516 Instruments for cohesive foil, 263-268 for non-cohesive foil, 259 for setting screw-posts, 248 sterilization of, 103, 105 used in examinations, 109-112 Interglobular spaces, 47 Irregularities of permanent teeth, causes of, 80-82 Irritants classified, 397, 398 Ivory's rubber-dam clamps, 181 Jack on pseudo-exposures, 417, 418 Jack's matrices and forceps, 284 Jaws, evolution of, 29 growth of, 63 Jenkins on porcelain inlays, 353 Jodococcus vaginatus, 93, 94, 99 K Kirk on discoloration in devitalized teeth, 446 Kirk's method of bleaching teeth, 455 INDEX. 631 Labial cavities, preparation of, 218, 219 Lactic acid, production of, in the mouth, 150 Laminae, 48 Lancing gums in primary dentition, 71, 72 Leptothrix, 96 buccalis maxima, 93, 97, 99 gigantea, 95 innominata, 92, 93, 97 racemosa, development of, stages of, 96-99 Leptotrichse, definition of, 86 Letamendi's method of local anaesthesia, 580, 581 Leucomaines, 103 Libby's rubber-dam clamp, 272 Lines of Schreger, 38 Lingual cavities in teeth, preparation of, 219, 220, 224, 225 Listerine, use of, in disinfecting cavities, 246 Local anaesthetics, 578-586 Local treatment of primary morbid den- tition, 71 Luxation, definition of, 501 M Mallet, Abbott automatic, 267 Bonwill electro-magnetic, 266, 267 mechanical, 267, 268 hand, forms of, 264 Snow and Lewis automatic, 266 Malpighian layer, 28 Mandrels, forms of, 293 Matrices, forms of, 283-285 use of, in amalgam fillings, 222, 323 in gold fillings, 283 McQuillen on bleaching teeth, 453 Mechanical separation of teeth, 175, 176 Meckel's cartilage, 30 Medicaments used in treatment of root canals, 436-438 Membrana eboris, 32, 48 Mental strain in children predisposing to caries, 128, 129 Mercurial pericementitis, 471, 473 Mercuric chloride, use of, in phagedenic pericementitis, 576 Mercury bichloride, use of, in disinfecting cavities, 246 Mesio-labial cavities, preparation of, 229 Mesio-lingual cavities, preparation of, 229 Mesio-morsal cavities, preparation of, 231 Mesoderm, development of, 27 Methyl chloride as a local anaesthetic, 581 Micrococci, classification of, 89 description of, 88 Micro-organisms, 84 Miller on mummification of pulps, 444 Miller's classification of fungi, 84 Milliamperemeters, use of, 206 Mirrors, forms of, 109, 110 Miscegenation, influence of, on caries, 127, 128 Mitchell's electric furnace, 352 Molars, cavities in, compound, 231-233 simple, 220-225, 227, 228 inferior, 21-24 deciduous, 25 superior, 17-21 deciduous, 25 Morphia acetas in hypersensitive dentin, 187 Morphine, use of, in devitalizing pulps, 424 Morsal edge cavities, preparation of, 220 Mould fungi, description of, 84, 85 Mouth and teeth, sterilization of, 104 examination of, 107 -mirrors, sterilization of, 105, 106 -props, 592, 601 Mucous glands, secretion of, 523 Mummification of dental pulp, 443-445 Mummifying pastes, formulae for, 444 N Napkins, exclusion of moisture by, 178 Nasmyth's membrane, 38 origin and function of, 54, 55 Nausea caused by rubber dam, treatment of, 183 Necrobiosis, definition of, 518 Necrosis as result of extraction, 620 causes of 519, 520 definition of, 401, 518 of cementum, 519, 520 treatment of, 520 Nerve-extractors, 430-436 Neumann, sheaths of, in caries, 159 Nitrous oxide as a general anaesthetic, 586- 590 use of, in hypersensitive dentin, 215 Noma, 70 O Obturation, definition of, 250 Occlusal cavities, preparation of, 221-223 Occluso-buccal cavities, preparation of, 232 -distal cavities, preparation of, 231, 232 €32 INDEX. Occluso-lingual cavities, preparation of, 233 -mesial cavities, preparation of, 231, 232 -mesio-distal cavities, preparation of, 233 Odontitis infantum, 70 Odontoblasts, 32, 34, 35, 48, 422 Operator, position of, 107 sterilizing hands of, 104 Ossification, 35 Osteitis as result of extraction, 620 Osteodentin, description of, 394 Ottolengui on use of antiseptics in mouth, 170 Ottolengui' s method of preparing gutta- percha points, 441 rubber-dam clamp, 181 Oxidizing agents, forms of, 451 Oxyhsemoglobin, definition of, 447 Palladium, use of, in alloys, 318 Parasites classified, 84 Parotid gland, excretion of, 523 Parr teeth-separator, 112, 175, 176 Pathogenic bacteria, diseases caused by, 96 mouth bacteria, 92 Patient, position of, 107 Peppermint, oil of, use of, in disinfecting cavities, 246 Pepsin, use of, in extirpation of pulps, 430 Pericemental membrane, 56 blood-supply of, 57 functions of, 57 nerve-supply of, 58 origin and composition of, 57 Pericementitis, causes of, 459^61 chronic, symptoms of, 466 treatment of, 466, 467 definition of, 450 differential diagnosis of, 462 general non-septic, 467 gouty, 550-567 hgematogenic calcic, definition and causes of, 550-558 pathology and morbid anat- omy of, 558-562 prognosis and treatment of, 562-567 symptoms and diagnosis of, 562 varieties of, 558 mercurial, 471, 473 prognosis of, 473 Pericementitis, mercurial, symptoms and diagnosis of, 472, 473 treatment of, 473 pathology of, 461 phagedenic, causes of, 568 definition of, 568 differential diagnosis of, 573 pathology of, 570 prognosis of, 573 symptoms and diagnosis of, 572, 573 treatment of, 573-577 prognosis of, 462, 463 ptyalogenic calcic, causes of, 541, 542 pathology and morbid anat- of, 542-544 prognosis of, 545 symptoms and diagnosis of, 544, 545 treatment of, 545-549 scorbutic, 470, 471 symptoms and diagnosis of, 470, 471 treatment of, 471 subacute and chronic, 465, 466 symptoms and diagnosis of, 461, 462 treatment of, constitutional, 464, 465 local, 463, 464 tubercular, 469, 470 Pericementum, diseases of, classification of, 459 Permanent teeth, calcification of, 78 eruption of, 77 order of, 79 extraction of, indications for, 596, 597 follicles of, 33 formula for, 2 irregularities in eruption, causes of, 80 local, 80, 82 resorption of roots of, causes of, 509, 510 pathology of, 510-512 prognosis and treatment of, 512 symptoms and diagnosis of, 512 Perry separator, 112, 175, 176 Perry's hot-air syringe, 189 Phagedenic pericementitis, 568-577 Phagocytes, 476, 477 Physiologic resorption, 77 Platinum, use of, in alloys, 319 Plug-finishing files and trimmers, 291, 292 Porcelain inlays, 352-354, 356, 357 INDEX. 633 Potassium bromide, use of, in pericemen- titis, 465 Primary epithelial cord, 30 Prophylactic treatment of caries, 166, 170 Proteids, analysis of, 447, 448 Protists, definition of, 85 Protozoa, definition of, 85 Ptomaines, 88, 102 Ptyalogenic calcic pericementitis, 541-549 Pulp, calcification of tissues of, 392 -canal pluggers, 439 -canals, enlarging of, 435-438 filling of, 438-443 medicaments used in treatment of, 436-438 preparation and treatment of, 432- 434 treatment of, in pericementitis, 463 -capping, 418, 419 -chamber and canals, opening of, 434, 435 calcic formations within, classifi- cation of, 390 devitalization and extirpation of, 423, 424, 430 exposure of, complete, treatment of, 423 false, treatment of, 416, 417 incomplete, description of, 419 due to traumatism, 421 prognosis of, 420, 421 symptoms and treatment of, 419, 420 stages of, 416 hypersemia of, causes and forms of, 375-378 definition of, 373 from constitutional causes, 385- 38 from internal local causes, 384 pathology of, 379 prognosis of, 382, 383 symptoms and diagnosis of, 378, 379, 387 treatment of, 383-385, 387, 428 irritation of, 373, 374, 396 mummification of, 443-445 plethora of, definition of, 386 suppuration of, 407-410 forms of, 409, 410 symptoms and diagnosis of, 410, 411 treatment of, 412 Pulpitis, acute circumscribed, 403, 404 diffuse, 404 Pulpitis, acute, prognosis of, 405, 406 symptoms and diagnosis of, 404, 405 treatment of, 406, 407 chronic, forms of, 412 definition of, 397 etiology of, 402, 403 pathology of, 403 Pulpless teeth, 431, 432 Pulp-stones (nodular calcifications), 391, 392 Pyogenic bacteria, 83, 91, 92 action of, 102 Pyorrhoea alveolaris, 74, 539 bacterial origin of, 539-541 constitutional origin of, 531-537 definition of, 530 etiology of, 531 instruments used in, 547, 548 local origin of, 537-539 synonymes, 530 treatment of, 545-549, 563-567, 573-577 Quinine, use of, in pericementitis, 465 Recurrent hemorrhage, 621 Replantation of teeth, 490-493 in phagedenic pericementitis, 576 preparation of tooth for, 491 Replanted teeth, resorption of, 77 Resorption of teeth, 76, 77, 509 Retzius on nerve-endings in pulp, 46 Rheostats, forms of, 204-206 Richardson's method of local anaesthesia, 579, 580 Rigolene as a local anaesthetic, 580 Robinson's remedy in hypersentive dentin, 192 Root development of teeth, 48 Royce plugger-points, 265 Rubber cups for polishing, 290 dam, adjustment of, 180-182 clamps, 172, 173, 181 exclusion of moisture by, 177, 179, 180 forms of, 179 punch, 182 shield, 183 sterilization of, 106 634 INDEX. Saliva, chemical reaction of, 523 composition of, 521, 522 description of, 133 ejectors, exclusion of moisture by, 179 Salivary calculi, composition of, 523, 524 instruments used in removal of, 528 pathologic effects of, 526, 527 treatment of, 527-529 varieties of, 524-527 Salol and paraffin, use of, in filling pulp- canals, 442, 443 Schizomycetes, description of, 84 Scorbutic pericementitis, 470, 471 Secondary dentin, 391, 421, 422 dentition, symptoms of, 79 separation of teeth, methods of, 112, 175 Septic infection, 102 intoxication, 102 pulp-canals, treatment of, 431 Sharpey's fibres, 160 Silver, electric conductivity of, 202 nitrate, use of, in caries, 171, 172 in hypersensitive dentin, 192 -tin alloys, composition of, 299, 307, 308, 311 use of, in alloys, 319 Sodium dioxide as a bleaching agent, 453- 455 Spirilla, definition of, 86, 89 Spirillum sputigenum, 94, 99 Spirochsete dentium, 94 Sponge-grafting, use of, in phagedenic pericementitis, 577 Staphylococcus, description of, 86 Sterilization of instruments and hands, 103, 104 of mouth, antiseptics used in, 104 technique of, 104 Stomatitis, catarrhal, 70 ulcerous, 70 Stomatoscope, 111 Stones for finishing fillings, 290 Stratum intermedium, 39 Streptococcus, description of, 86 Strise of Retzius, 37 Sublingual glands, secretions of, 523 Submaxillary glands, secretions of, 523 Sulphuric acid as a bleaching agent, 455 use of, in enlarging canals, 436 Syphilitic teeth, 129, 130 Syringe electrode, 213 water-, use of, 241 Tannic acid, use of, in hemorrhage, 621 Tape for separating teeth, 176 Teeth, anatomy of, 3 architectural design of, 4 blood-supply of, 618 calcic deposits upon, 521 character of, in gouty subjects, 557 deciduous, 24, 25 development of, 26 dislocation of, classes of, 501 prognosis of, 504 treatment of, 501-504 eruption of, 59 evolution of, 30 examination of, 107 extraction of, 595-623 fractured, union of, 507, 508 fractures of, classification of, 505 in extraction, 619 treatment of, 506, 507 green stains upon, 521 implantation of, 496-500 morphology of, 26 number and classification of, 1 origin of, 26 permanent, see Permanent teeth replantation of, 490-493 transplantation of, 494-496 Temperaments, 162, 163 Temporary stopping' uses of, 332 Tin and gold in combination as filling- material, 286, 287 methods of introduction of, 287 -foil, forms of, 285 therapeutic action of, 286 use of, in alloys, 319 in filling pulp-canals, 439, 440 Tobolt's laryngeal forceps, 601 Tomes, granular layer of, 47 zone of, 156 Tooth, apical foramen of, 4 cervix of, 4 crown of, 4 morsal edge of, 4 -paste, formula of, 168 -powder, formula of, 168 pulp-chamber of, 4 -pulp, definition of, 55 histological composition of, 55 root of, 4 Toxines, 102 Transplantation of teeth, 494 method of union in, 496 INDEX. 635 Transplantation of teeth, prognosis of, 496 preparation of tooth for, see Eeplanta- tion Transplanted teeth, resorption of, 77 Tropacocaine as a local anaesthetic, 583, 584 Truman on secondary dentin, 422 Truman's method of bleaching teeth, 451, 452 Tubercular pericementitis, 469, 470 Tubuli, bacteria in, 159 expansion of, in caries, 157, 158 Turnkey, use of, in extraction, 602 Varney's gold-pluggers, 264 Varnishes, use of, in lining cavities, 344, 345 Veratria in hypersensitive dentin, 187 Von Beust's method of preparing gutta- percha points, 442 W "Warren's screw-gag, 601 Watts' s crystal gold, 268 Weagant's method of using porcelain in- laj^s, 350, 351 trephines for inlays, 351 Webb's pluggers, 264 Wedges for separating teeth, 175, 176 Weston's milliamperemeter, 207 Williams on leptothrix, 99, 100 Witzel's method of mummifying pulps, 443 Wood points, use of, in filling pulp-canals, 440 polishing-points, 289 Woodward's double screw matrices, 285 separator, 175 Wright's method of bleaching teeth, 452 Wurtz on analysis of proteids, 448 Younger on implantation, 496 Zinc cements in lining cavities, 327, 328 varieties of, 336 chloride in hypersensitive dentin, 191, 192 oxychloride as a capping-material, 418, 419 as a fiUing-material, 336, 337, 339 characteristics and properties of, 338, 339 mixing of, 337, 338 preparation of, 337 use of, in filling discolored teeth, 452, 454, 455 in filling pulp-canals, 440, 441 oxyphosphate as a capping-material, 419 crushing stress of, 343, 344 in hypersensitive dentin, 191 mixing and introduction of, 341, 342 penetration of moisture in, 343 preparation of, 339-341 properties and uses of, 341 shrinkage and expansion of, 342, 343 oxysulphate as a capping-material, 344, 418 use of, in alloys, 319 THE END. ^r^^^xM ' 1 RK501 ,. Marshall M25 Copy 1 RK 501 mRT ^'^'^'^'^'^^ '^"■"" '''''"^'l?,i?,?.,a,9.lP.[.actjce of operative den 2002367971 U'i