Columbia (MnitJew^ftp itttljeCtlpofBewgork THE LIBRARIES iHebical Hibrarp Digitized by the Internet Archive in 2010 with funding from Open Knowledge Commons http://www.archive.org/details/technicscopeofcaOOchay CAST GOLD AND PORCELAIN INLAYS TECHNIC AND SCOPE OF CAST GOLD AND PORCELAIN INLAYS WITH A CHAPTEK OX ENDOCRINODONTIA, OE THE DUCTLESS GLANDS- THEIR EXPRESSION IX THE HUMAN MOUTH BV HERAIAX E. S. CHAYKS, D.D.S. NEW YORK CITY With 372 lUiislrations ST. LOUIS C. V. MOSBY COMPANY 1920 7^ /"^J -^ (1 Copyright, 191S, Br C. V. Mosbt Company Pl'CSS of C. V. Mosbij Coiniiunij St. Louis 2 I I In My Firm Conviction that the Trials and Tribulations which Harass Us Are But an E^^DENCE of Our Ulti- mate Victory Over the Evils which at Present Enslave Us, This Book Is Af- fectionately Dedicated to jMy Fel- LOWMEN. PREFACE Tile introduction to this hook was wi-ittcii in the (.ai'ly ])ai't of 1918, Ix'l'oi-c the pcoph' of the worhl cncii drcaiiUMl of the tci'- rihle catasti-o))h(' \\hich has since overtaken thi-ee continents and tlireatens to I'oice llie reniainin<2,- ones into the horrible and voracious Avliiilpool of an uncivilized warl'ai-e. I am includin,!;' this introduction in S])ite of pressure h]-ouf;ht to bear u]K)n me, because I feel that a new order of tliinf^s in "-eneral is about to appear in the world and I feel im- pelled to do what I can to speed the day of clearer thinking, greater tolerance, and more virile idealism. It holds somethino- for the man or woman who will read it with the same sincere desire and re^^ard for truth and equity and justice which the author felt himself possessed of when he wrote it. I want to at this time pay my respects and acknowled^-e my obligation to the many writers of the many hel])ful books I may have quoted in this volume, and express my thaid^s to the many men in my profession who have labored and are laboring in the same or similar pursuits, and Avhose work has been helpful to me to no small degree. I want to acknowledge my deep ol)ligations and register a jsupil's sincere affection for my dear friend and teacher. Dr. Joseph Fraenkel, of Xew York, for the many interesting, help- ful, and clarifying hours of instruction he unseltishly devoted to me and to many others, and which have made me familiar with a new, a higher, a clear, sane conception of the physiologic and the morbid ])roctsses which affect living beings and things. My thanks to my friend Dr. Chas. G. Taylor, an associate of Dr. Fraenkel, for his measure of helpfulness in the correct interpretation of the functions of the endocrines in their asso- ciation with the dental a])])aratus. My thaidvs to Dr. J. 0. Lief who kindly wa(hMl through the entire inannsci-ijtt to foi'nndate the questions at the end of each chapter. Manv thanks to all mv friends who liav(> stood l)v me and 10 PEEFACE encouraged me. To tlie officers and members of the Chaves Dental Club whose loyalty I cherish and rejoice in, whose ideal- ism I admire and ajiprove of, and whose success is my ardent desire. Last, Init not least, I wish to exjjress my sincere aj^pre- ciation and thanks to my wife who has been a source of genuine inspiration. H. E. S. Chayes. New York City. CONTENTS CHAPTER I INTRODUCTION Soquciicc of Thought and Its Value in Toaching, 21; The Chief Factors Induc- ing Coordinate Mental Efforts, 24; Some Rational and Acceptable Conclusions, 48. CHAPTER II THE FUNCTIONS OF THE TEETH The Functions of the Teeth, 52; Passive Reciprocal Functions, 58; Active Reciprocal Functions, 58. CHAPTER III THE CAST GOLD INLAY The Cast Gold Inlay, 62. CHAPTER IV SELECTION OR ELECTION OF THE CASE PRESENTING A CAVITY The Selection or Election of tlie Case Presenting a Cavity, G4. CHAPTER V CAVITY PREPARATION Geometric Landnuirks of Teeth, 65; Hygienic Landmarks of the Teeth, 69; Cavity Preparation, 76. CHAPTER VI THE MESIO-DISTO-OCCLUSAL CAST GOLD INLAY The Cast Gold Complement for a Tooth Presenting a Mesio-Disto-Occlusal Cavity, 120; Cavity Preparation, 121. CHAPTER VII THE SELECTION OF THE PROPER WAX The Selection of the Proper Wax, 127. n 12 C(1NTKNTS C I r A P T E R Y 1 1 1 :\IAKl\(i AND CARVINCt OF THE AVAX INLAY BY THE USE OF THE DIEET'T METHOD Making aiul Carving uf tlio Wax Inlay by the Use of the ]>iieet MetlioJ, 131. C H A P T E R IX TAKING AN IMPRESSION OF THE CAVITY AND MAKING A DIE FOR PROCEDURE BY THE INDIRECT METHOD Taking an Impression of the Cavity and Making a Die for Piocedurc by tlic Indirect Method, 139; The Making of the Amalgam Die, 148. C II A P T E R X THE INVESTMENT, OR REFRACTORY, COMPOUND The Investment, or Refractory, Conipound, 158; Silicon, IGO; Calcium, 1G2; Magnesium, 162; Alumina, 163. CHAPTER XI THE DRYING OUT OF THE MOLD AND THE B1TRNL\(! Ol T OF THE WAX :\IODEL Tlio Drying Out of tiie Mold and tiic Burning Out of the Wax Model, 173. CHAPTER XII THE (AST1N(! ol-' TIIL MOLTEN ,MLTAL INTO 'VWK .MOLD The Casting of the :Moitcii Metal into the Mold, 178. CHAPTER XIII THE METALS FOK TIIL I.\LA^' WOIJKLIJ Til.; Metals for the Iiday AVorkci, ls2. C H A L' T E R X I V TiiL (AsTLXo OI-' 'II II'; .M(>i/n;.\ mi: tal i.\t<> tin-; .mold .\.\d A CONSIDI^ILVTIO.X OF TIIL \'.\IGo| S M .\( I II X LS L.Ml'l>o^■|•:l) The Casting of tlie M(.lt<-n Metal into thf .Mold and a Consideration of the Various Machines Eini)loyed, 187. CO NTi: NTS 13 C TT AFTER X V THE CLEANSING OF THH CASTING IN nVDKOFLTTJRIC AGTD AND IN A SODH'M BIGAKBONATK I5ATII T1h> Clcjuisiiin' of tlio Casting' in llyilrofiudric Acid ami in a Sodiuni Biear- Ixinate I'.atli, lidO. C H A P T 1'] R X Y I KKAFOVAL OF THE ENCESS OF METAL, THE POLISHING, AND THE ('FOMENTATION OF THE INLAY Removal of the Excess of Metal, tlie Polishing, and the Cementation of tlio Inlay, 213. C H A P T E R X V 1 1 THE SPLINTING OF LOOSE TEETH BY MEANS OF INLAYS The Splinting of Loose Teeth by Means of Inlays, 218. CHAPTER X^^III EXTENSIVE RESTORATIONS OF OCCLUSAL BALANCE BY MEANS OF GOLD INLAYS Extensive Restorations of Occlusal Balance by Means of Gold Inlays, 236; Construction of the Splint, 245. CHAPTER XIX GOLD INLAYS AND THE SILICATES OR PORCELAIN Gold Inlays and the Silicates or Porcelain, 2G9. CHAPTER XX THE PHENOMENA OF LIGHT AND COLOR The Phenomena of Light and Color, 302; Reflection and Refraction and Ab- sorption, 304. CHAPTER XXI THE PORCELAIN INLAY The Porcelain Inlay, 322; Cavity Preparation, 328. CHAPTERXXII ENDOCRINODONTIA, OR THE DUCTLESS GLANDS— THEIR EXPRESSION IN THE HUMAN MOUTH Endocrinodontia, or the Ductless Glands — Their Expression in the Human Mouth, 359. ILLUSTRATIONS FIG. PAGE 1. Diagram slio\vin<;' rccipiocal functions of the tooth 59 2. Showing diagiammatically the various surfaoos, lino an^los, and cutting, or point, angles of incisor teeth 06 3. Showing diagrammatically the surfaces, line angles, and cutting, or point, angles of a cuspid G6 4. Showing diagrammatically surfaces, line angles, and point angles of bicus- pids and molars 66 5. Immune areas of anterior teeth and susceptible areas 70 6. Immune areas of posterior teeth ... 70 7. Immune areas and susceptible areas of posterior teeth 70 8. A set of chisels used by the author in tooth structure cutting 72 9. Cross section of molar tooth illustrating prepared cavity and bevel ... 74 10. Cross section of molar showing a disto-occlusal cavity 74 11. Longitudinal section of molar, showing mesial and distal planes .... 78 12. Cross section of bicuspid 78 13-17. Five views of an upper first bicuspid presenting a simple occlusal cavity, and the east gold inlay made for it .80 18-24. Seven views of a first right lower bicuspid presenting a compound disto- occlusal cavity involving also the cervical portion of the buccal wall, restored with a cast gold inlay disto-occlusally, and a porcelain inlay buccally 82 25-32. Eight views of an upper first bicuspid presenting a mesio-occlusal cavity, and the restoration made for it 84 33-37. Five views of a lower second bicuspid presenting a mesio-disto-occlusal cavity, and the inlay made for it 86 38-46. Nine views of a mesio-occlusal cavity in a first lower bicuspid, and restoration made for it 88 47-54. Eight views of a lower second bicuspid presenting a mesio-disto-occlusal cavitj', and the restoration made for it 90 55-60. A first lower molar presenting a labio- or bucco-occlusal cavity, and the cast gold inlay made for it 92 61-68. A lower molar presenting a disto-occlusal cavity, the lower half of the buccal wall being involved to the full mesial-distal extent .... 94 69-78. A disto-occlusal cavity in an upper molar and a disto-buccal cavity in the same tooth. Two cast gold inlays for the respective cavities and three views of the finished operations 96 79-86. A mesio-disto-occlusal cavity in an upper molar, also a buccal cavity in the same tooth 98 87-88. Two illustrations of teeth worn down by attrition, restored by means of the cast gold inlay, imitating the conditions of adjacent teeth . . 100 89-94. Left first lower molar presenting deficiency of occlusal third. Views illustrating preparation of cavity and restoration made for it in the shape of a cast gold inlay 102 15 16 ILLVSTItATlOXS FIG. PAGE !'.j-]"2. A coinplcx finity in an u]i]i('r niolav invnlvin;;' i'vovy surface of the tooth, and cast gold inlay made for it 104 103-111. Nine views of a second lower niohir presenting a niesio-disto-oc- clusaidinccal ca\ity and two interlocking cast gold inlays made for it IOC. 112-119. A mesio-occlusal-palatal caxity in an iqipcr molar restored by means of a cast gold inlay lOS 12U-li!7. Eight views of a nicsio-disto-occlnsal cavity in an u]ii)('i- second lii- ciisi>id, and the cast gold inlay ma 143. Tiie final cut. The l)evel u]ion the occlusal surface continuous with the niesio-buccal, disto-buccal, mesio-lingual, and disto-lingual guides of the cavity, which guides arc beveled outward 123 144. The wax inlay made for the mesio-occluso-distal ca\ity 124 14."3. The fini.shed inlay in position upon the tooth 124 14(i. Tiie Taggart automatic wax warmer 132 147. A glass of water with cork and pins for submerging wax .... 134 148. A spatula, a set of right and left and straight flat htirnisliers. lancets, right and left carvers, and hand drills 137 149. Method of making a handy matrix 141 ].">0. Illustrating a liandy matrix in position upon a molar 141 1;j1-1.j2. Hinged traj's for taking correct impressions of mcsio-disto-occlusal cavities and teeth npo?! whieh they pi-esent 144 l.")3. JJisto-occlusal cavity tray 144 1.54. Mesio-occlusal cavity tray 144 l.l.j. Hinged tray for anterior ti'cth 14 1 1~}G. Hinged traj' in position 1 I." 157. Hinged tray in closed position 11") 158. Complete impression of tooth and cavity emliedijeil in jijastei' impics- sion of adjacent teeth, ready for the paeking oC anial^ani die . . 117 159. Complete iirii)ression of tooth and cavity, removei. Measuring posts in same clamps as in preceding cut, but with the dis- tance between them increased to 10 mm 220 179. Showing position of measuring posts for all measurements from 10 mm. up to and including 25 mm 220 180. Measuring posts in same clamps as in Fig. 179, Imt with the distance increased to 40 mm 221 181. When the distance to be measured exceeds 40 mm., the parallelometer is reversed and the measuring posts are placed in the clamps as shown 221 182. Measuring posts in same clamjis as in Fig. 181, but the distance has been increased to 55 mm 222 183. The above cut shows where the parallelodrill should be oiled . . . 223 184. Distance established between cuspids 224 185. Showing the operation of the parallelodrill reaming out two root canals in the two upper cuspids to receive the split pin and tube attachments 224 186. Showing the method of transferring the distance from the parallelom- eter to the parallelodrill 226 187. Distance established between cuspid and lateral on opposite side of the arch 228 188. Distance established between right cuspid and left lateral .... 228 189. Distance established between left cuspid and right central . . . 230 190. Distance established between right cuspid and left central .... 230 191. Finished splint ready to be inserted 232 192. A case of extensive restoration 237 193. A view of a splint made for a case of extensive restoration .... 247 194. Another view of the splint shown in Fig. 193, which, when it was first made and worn, covered all the anterior portion of the jaw, as well as the part now occupied l)y it 247 18 ILLUSTEATI02TS FIG. PAGE 195. The splint in position on the model 247 196. An occlusal view of the models of a ease, showing the terrible havoc wrought by neglect 252 197. The model of the upper teeth of case after six months' treatment . 252 198. The lower model model showing clearly the rebuilding of the anterior, and some of the posterior, teeth by means of the cast gold inlay and cast base crowns 252 199. The upper and lower models in occlusion 252 200. An occlusal view of a finished case of extensive restoration by means of cast gold inlays and two upper bridges 254 201. A side view of the same case — upi^er and lower models in occlusion . 254 202. Diagram of face showing normal proportions 255 20.3. Chart showing geometrical construction of crown 256 204. Illustrating determination of proximal contact between molars . . 258 205. (1) A horizontal section representing the occlusal plane of the middle third of an up^jer second bicuspid. (2) A horizontal section repre- senting the occlusal plane of the middle third of a lower second bicuspid 259 200. Showing how perfectly occlusal surfaces may be carved in the wax and reproduced by means of the casting process 260 207-209. Three illustrations of beautiful occlusal surfaces 263 210. Xote the two illustrations on the lower i)ortion to the left, with their inefficient occlusal surfaces, and compare the four other illustra- tions with their definite sulci eusps, and fissures 264 211. Showing the ways in which attrition manifests itself in different types 265 212. Another type of the result of attrition 265 213-218. A case of extensive restoration 267 219-225. Gold inlays and porcelain or the silicates. A number of views of a lower central fractured in a fall 270 226-232. A number of views of a lower lateral restored by means of a cast gold inlay and synthetic porcelain 272 233-239. A number of views of a lower lateral involved by fracture and decay restored liv tlio use of a gold inlay in conjunction witli silicate cement — root filli-d 274 240-246. A number of views of a U>wvy lateral friuturcd in a fall. Extir- pated pulp 278 247-253. Seven views of a lower cuspid, presenting another type or restora- tion, also a combination cast gold inlay and porcelain insert . . . 280 2.54r260. Seven views of a broken-down cusjiid restor('(l with a cast gold in- lay and a porcelain insert 282 201-267. A left upper lateral presenting a mesio Inbin iingno-incisal d((fi- ciency restored to use and cosmetic .'icf'c|jtaMcncss by a cast gold inlay and synthetic porcelain 284 268-275. View.s of a right upper central presenting a large mesio-labio-linguo- inci.sal djcficiency, restored to use annd cosmetic acceptableness by a cast gold inlay and porcelain insert 288 ll.LlIS'rilATfON.S 19 FIG. PAGE 276-282. Views of a left upper central presenting a mesio-disto-labio-iucisal deficiency, restored to use and cosmetic nccoptablcncss by a cast gold inlay and synthetic porcelain insert 290 2S;!-28i). A nunil)er of views of a right upper central pres^eiiting an eroded and pitted labial surface, a niesio- and disto-proximal cavity, and a lingual enamel surface which was perfect, as was the incisal eilgc 292 290-296. Seven views of another type of restoration in an upper cuspid . . 296 297-303. Seven views of a right upper (■us])i(l ]ir('sciiting a prehenso-labio- linguo-uiesial deficiency 298 304. Diagram showing refraction of light 307 30;"). Color chart 316 306. Method of obtaining a separation between two teeth which are to be inlayed 330 307. Method of separating two teeth that lean towards one another . . 331 308. Manner of preparation of a simple cavity for a porcelain inlay . . 332 309-311. Foil between two layers of goldbeater's skin 333 312. A set of eight glass burnishers used in adapting a foil matrix to the cavity in a tooth or in a die 334 313. A set of tantalum instruments 334 314. A small platinum tray 334 315-318. The mixing of the silver amalgam 335 319. Foil reposing between the layers of goldbeater's skin and the applica- tion of the hand swager 336 320. A disto-labial ca\'ity in a central 338 321. A strip of x>latinoid bent at an obtuse angle and perforated so as to hold the compound which is softened in the flame and deposited upon the improvised tray 338 322. Carrying tray and compound between the teeth and forcing the ma- terial into the cavity 338 323. Lingual view showing surplus of compound 338 324. Flat straight spatula to aid in placing and holding impression material 338 325. A labio-disto-lingiial cavity in a lateral 339 326. First step in formation of tray 339 327. Second piece of metal 339 328. Improvised slide made from metal shown in Fig. 327 to fit into that shown in Fig. 326 339 329. Showing completed slide 339 330. Slide carrying compound and taking impression of lingual part of cavity and all of distal part 339 331. Slide is raised and the impression is removed from tiie tooth in a lin- gual direction 339 332. A linguo-mesial cavity in a lateral 340 333. The tray 340 334. The impression 340 335. The plastic instruments used as an aid to project the compound into the cavity 340 336-338. Showing cervical cavity in a cuspid, the partly and completely formed tray 340 20 ]llustj;atioxs FIG. PAGE 339-341. A cervical proximal in a lateral and the partly and the com- pletely formed trav for taking impression 341 342-346. A cervical cavity in the disto-labial surface of a molar, the partly and the completely formed tray with compound in position on the tooth, and the impression of tlic cavity 341 347-351. Same as shown in Figs. 340 to 349 on opj)ositc side of the arcli . 342 .■>32-3j4. a disto-occlusal cavity in an upper molar, tlio partly and the coin- jiletely formed tray 342 345-357. A labio-occlusal cavity in a molar, the imrtly and the completely formed tray 342 358-360. Another type of disto-occlusal cavity in a molar, the i^artly and the completely formed tray for taking impression 342 361-362. A mesio-occlusal cavity in a lowar molar and traj'' for taking impression 343 363-366. A mesio-disto-occlusal cavity in a molar, partly and completely formed tray for carrying the compound to take impression of this cavity 343 367-370. M. O. D. cavity in bicuspid, partly and completely formed tray for taking impression 344 371. A handle and set of trays, or cups, which may be trimmed to suit the case to facilitate the taking of impressions of various cavities . . 344 372. The Protector of David 378 CAST GOLD AND PORCELAIN INLAYS CHAPTER I ixTiJoDrcrriox SEQUENCE OF THOUGHT AND ITS VALUE IN TEACHING U.sefiiliiesf<, in the broad sense of the word, determines the value of man to mankind. Usefiihiess is tlie purpose of this Yohime. To help, to improve, to simplify, to make clear obscure- problems in tliis particular field, will mean a better equipped I^rofession, and hence must mean betterment to the great human family depending- ujion our profession for their comfort and health. The ambition to determine definitely foi' the profession the best mode of procedure in this work, to coherently elucidate innumerable points much discussed and poorly understood, to delve into all crevices of the task, to throw the ray of sane, investigating reason into tlie shadows of the recesses, to at- tempt and succeed in proving all statements, to evade noth- ing, — a task to be reckoned with ])ut worthy of the best efforts. To best serve its purpose, this volume must be both ele- mentary and postgraduate, and no apology is offered if, at the beginning, it may appear to the student that he is reading some- thing he already knows. In fact it is l)est to make it Y)\i\in now, that in order to be truly useful, and readily comprehended, teaching must always l)egi]i with something already well estab- lished in the student's mind. In attempting to teach a body of students or a single stu- dent anything their or his knowledge of which is deficient, it is conducive to best understanding to start at first principles. To be efficient, a text])ook nnist l)e so written, and par- ticularly so begun, that the first thing to greet the student 21 22 CAST GOLD AXl) POltCELAlN INLAYS iiiiiid is a statement of a fact, or a fact, already lixedly estab- lished in liis mind; and from that lone hut well-estahlished fact, all avenues of research and investigation and proof must issue, to converge again at and upon a perfectly logical and hence well dovetailed conclusion. Thus it is seen that sequence in a textbook plays a great part in determining how valuable the book is to i^rove to the student. AVe must have then, a well-known fact, a universally known fact, so far as our profession is concerned, and proper sequence as we go along; and we must, after diverging with proper sequence and reaching into every cranny of the process, so con- ^■erge our thoughts that only one, and that the proper conclu- sion, is possible. The foregoing qualities will make up a useful and neces- sary textbook. It is easy for the student to prove the real value of this book to himself by carefulh^ reading it from the beginning, and if he reaches his conclusions before he finishes the last chapter, and if his conclusions coincide with the con- clusions of the book, then the correctness of its logic is proved, and its value as a textbook becomes apparent. If I were to attemj^t to teach the science of cooking, I should begin my textbook's first chapter with the statement that food is absolutely essential for the maintenance of the various functions that make up the activities of mankind, and the animal as well as the vegetable kingdoms. That would be stating a fact already well established in the student's mind, — so fixedly estal)lished that no amount of argument could dis- lodge it. From tliat lone fact, I could send out mental expedi- tions of investigation into every phase of the question, covering- food as to kinds, quantity and quality, necessity and luxury; food for man, for animal, and for vegetable: and we could, after discussing all of Ihcni, llicii' origii; and pi'cpai'ation, and reasons thereof, tlieir coinijai-ative values and reasons there- for, so converge my (iiidiiigs as to veiy propeily feel that the very best thought with which to end the l)ook would be the food thought. AVere I to attemj)t a work on aichitcclurc, docs it not seem to you, the n('o])liytc, the iininil ialcd, tlial i1 would lie best to SEQUENCE OF TfKKTGlIT 23 start at tlie vei-y begiiiiiiii*;' of tilings and slate a fact already fixedly established in your neojjliytic mind t Sui)pose then, 1 were to say that man is poorer than animal in brnte force, and richer than the animal in intellect; and that even preliistoric man had a cave to live in, to house liiiii and Ids descendants: that would be stating- a simi)le and true fact, already well estab- lished in the student's mind (in any mind for that matter), and how easy it would be to logically follow up that simple state- ment of fact and show comprehensively that that cave or dwell- ing varied in size with the requirements of the human numer- ically, and that it varied in kind Avith the requirements of the human geographically. Could I not very naturally go on to show how, with the evolution of man from preliistoric tyjje to complexly civilized variety, desires, requirements and habits changed and brought on housings as different from the prehistoric cave in appear- ance and in service as, let us say, Gladstone differed in type and mentality from prehistoric man? So may I not very simply, and very truthfully, and witli clarifying and illuminating sequence, go to the next statement which tells us that with the great increase in the human species, came the emigration of tribes into various corners of the globe, and that their various requirements in the direction of being properly housed, were influenced as before by geographic and geologic conditions ? Perhaj^s too, in their travels to their new locality, they had imbibed some of the beauty of Nature's vast architecture, and had become desirous of injecting part of it into their own handiwork. This seems very reasonable, and so one can go on and readily proceed to show how the architecture of today originated, how it grew and developed into its apparent complexity, but in reality into its scientific simj)licity. I can trace them all, the Greek, the Roman, the Ionic, the Renaissance, etc., and can, after tracing them all with proper sequence and perfect logic, so converge my findings as to very pro23erly feel that the very best thought with wliich to close tlie book on archi- tecture would be the thought that the human is poorer than the animal in brute force, but richer than the animal in intellect. So, in the beginning, for his own preservation and prote'Ction, 24 CAST GOLD AXD POKCELAIX INLAYS and for the i)i'otection and preservation of liis species, lie built himself a cave, and it grew and he grew; and, because of superior intellect, he outgrew the cave and built for himself a hut; and because his intelligence further grew, he discarded his hut and built for himself a house — mark yon, a house. Still his intellect grew and he traveled; and he saw the wonderful beauty of the he'avens and the earth, and the sun, and the stars, and the streams, and the oceans, and lo and behold! his desires to see all these beauties before him at all times were father to his attempt to reproduce them in his dwellings! So his intellect grew, and so art was born, and so man builds for himself palaces and paints for himself joictures of the things he has seen in his migrations and travels. ^&' THE CHIEF FACTORS INDUCING COORDINATE MENTAL EFFORTS The Optic Sense A fact has l)een poorly stated, or a statement has been improperly jn-esented, unless it jjroduces within the mind of the i^erson to whom it is i)resented a coordinate effort reaching out for further information on the same subject. Thus a suljject is never closed, never completed until its power to awaken mind-developing desires and efforts foi- furtlier research in it, has l)een exhausted. Mental efforts are of two kinds — iirni(l-liii'biiig. Botli may be coordiiiaie, and hotli may mean mental activity. One is productive and good; one is destructive and Imrlful. One, being goo to tlie many. So it would seem that good I'oads are bad when they ai'o very good, and bad roads ai'e not good even because they are bad. But it seems that the multitude might learn I'rom the rail- roads, and have a plan, a starting point and a destination — manage its affairs well. Given these units working in unison. SKQIIEXCK Ol' 'I'linlCll'l' 35 a iiiullil ui-ute Force and his roar. Tlie enti'ance was just l)arely laigc enough to adinil the oecu- ])an1, hilt I'ai- trto small for the gi-eat hulk' of the giant ehier. \\'ea]< llands sat upon a stone and s1ai'e(| into the seini- ' in front of him, nnd in its wanderings, the sticl\' enibeddiMl it-cIf in a jagge(| hole of a I'ound jjiece of .SEQUENCE OF THOlcniT 39 stone. Weak Hands lu^\i;('(l at the stick to ti'cc it tVoin its prison, hul in \aiii. His inal)ility to S('|)ai'al(' the two t]iin;;s irritated liini. The small piece of stone was held in j^laee ))y a larger piece of the same material, and tlic stick was held in the jag<;ed hole of tlie smaHer stone. The constant tn^'^in*;- of Weak Hands tinally moved the lar^'er stone and snddeidy tiie queer conil)ination of stick and stone held in the right liand of "Weak Hands, as liherated, and, describing an arc, tlie stone struck tlie cave dweller full on the tein])le, while he, losing his l)alance, found himself on the ground, speculating as to the l)eculiar, strange, and unfriendly behavior of his stick and stone. A change came over tlie cave man. He raised himself care- fully and very slowly into a sitting j^osition, and he looked first at the stick, then at the stone on the end of it; then he deliber- ately felt his head where it had come in contact with the stone, and then he again looked at the stone and the stick, brought them nearer the entrance and the light, in order to discover the source of its power. With that end in \ie\x he swung it slowly and gingerly toward his head. In spite of his care the force of the contact startled him and he tried again, tliis time on his thigh. The result was a grunt of i)ain and satisfaction — if we can conceive any such combination. We may recognize now that there was no aimless move to be detected in the activity of Weak Hands. He was alive, and intelligence was dawning; that means that his movements had behind them the quality of volition. The accidental and then the premeditated touch or l)low he had given himself started things going in his mind. The touch roused a mental effort which crystallized into thought, and these thoughts were mani- festing themselves in his immediately following physical acts, as we shall see directly. Weak Hands crawled out of his cave into the great oi)en and stood erect. In his right hand he carried the wonderful stick and stone; he l)rought it up directly in front of him and studied it in awe for a spell. Suddenly he grasped the stick firmly at the extreme end and swung it with all the force that was in him to send the stony end of it swishing into the earthy side of his cave, burying the stone from sight. Weak Hands 40 CAST COT.D AND POllCKLAlX IXLAVS ^vas teiisi'ly alert now. lie witlidrew liis iiiid inid looked at it again. It was none the worse for its work. He handled it earet'ully now — we might say he fondled it; he stroked the stick and stone with his left hand, he brushed the side of his face against it, and caressed it with his eyes. This satisfied him for a few brief moments, then the cave man became strangely active. He found an enormous stone near his cave; this he moved up and barred the entrance. Then he turned his back upon it, his extended right hand held the stick and stone up before and al)0ve him; for a moment his eye was fixed upon the stone, and we can see the light of definite inalterable j^ur- l)ose suffuse his entire being; his right hand droits to his side, and Weak Hands is off in his search for both Lily-white and Brute Force — and pray iiote he has Ijurned his bridges behind him. AVitli rapid strides he walked in tlie direction leading to the giant's cave, a considerable distance off. From afar he de- termined that Brute Force was asleep; his snoring caused the very ground to reverberate . Ijily-white sat beside the sleeping mass of l)]iitality. When the familiar guttural sound of "Weak Hands roused her fi-om her stu])id fear, she looked, and in com- pliance Avitli an imperative gesture from the man with the stick and stone, she carefully crawled a few steps away from Brute Force, then arose and walked to meet her caller. Another guttural sound from Weak Hands and Brute Force opened his small eyes to l)eliold his pestering rival trespassing upon his preserves. With a roar that struck terror to Lily- white and brought her to a standstill. Brute Force was up and at her in a moment, lie grasped her by the hair and spun her aiound toward the cave, then he made foi' Weak Hands. A hideous grin from his glutton face, liis ponderous, liaiiy hands extended befoie liim, he advanced toward the much smaller AVeak Hands wlio calmly wailed. Tills irritated Bi-ule Force, he misse<| tjie si)oi't of chasing the ferret as heretot'oic, and it iionj)lussed him sounnvhat to see anotlier one of the trilx* who dared stand si ill while he, the chief, was ad\aiicing jx-llowing with I'age. The fiiant ]'eache(l out willi his right lianAIX i:XLAY,S and moved lier hand caressingly across liis face, liis chest, his arms. He looked at her face, and her breast and her hair, and his arm grew tighter aronnd her. His breath came faster and his nares ex23anded. Tims they stood for a spell^ — Weak Hands and Lily-white. Then they raised their eyes to the far-off coun- try and saw tlie sun go down to its rest. It calls for no very great analytic power to enable one to discern how far-reacliing an influence the sense of touch had in awakening mental efforts within the three characters in the jjreceding sketch, and it requires no very keen sense of judg- ment to realize that they were variously influenced by the same sense of touch. To Weak Hands the accidental touch meant the awakening of a mental effort Avhich crj^stallized into coherent thoughts, which manifested themselves in a series of distinct physical acts, i^artly involuntary and automatic, partly premeditated, and for lum ultimaiely altogether l)eneficial. To Brute Force, the i^remediated touch or blow from the stick and stone controlled by Weak Hands awakened within him mental effort of such low order that it crystallized into thought of such i)oor rationality, that these thoughts manifested themselves in such irrationally aggressive physical acts that they brought to him destructive tactics from "Weak Hands and tlieir destructiveness increased with the irrational perseverance of offensive tactics on the part of Brute Force. Thus the ])('! roi-nianc(* went on until the giant had fallen an easy i)rey to tlie mind-developing mental effort of AVeak Hands, on one side, and his own mind-disturbing mental effort on tlie othei'. Xoi' did the cessation of the battle ])rove the end of the series of menial cIToiis, ci-ystallizing thoughts, and ])liys- ical acts, and again mental efforts and ciystallized thoughts, etc., so far as AVeak Hands was concerned, and thi'ougli him so far as Lily-white was concei'ucd. The moment his loudi of the wenixtn hecame |»remeditale(l, it was tlie manifeslat ion of a thonghl crN slalli/eil From a pi-e- vious mental effort, and. in Inrn, lonse*! menial efforts which were secondai-y. (••lordiiuilc ;iii(| deducliNc, which secondary co- oi'dinale and dednetixc nienlnl effoi-ts again ci\vsiallized inio cohereid Ihonghl, which cohei-eiil Ihonght again maiiires1e(l si;()ii;.\('K OF Tiioi'diiT 43 ilscir ill (lislincl pliysical acts. This went on in rotation nntil the power of this newly found I'liciid to awaken within liini niind-developin^" desii-es for fuiiher j-eseai'cli in it or with it was exhausted. It is quite sale to assume that this sti(d<; and stone as the crude ancestor of the ino(U'rn scej)ter lias held, anitter taste, and, sugar off, the bitterness remains. 44 CAST COLD AND PORCELAIN INLAYS Millions of books liave been written by as many writers upon as many subjects, and tliese books have been read by many more millions of readers, sometimes for mere amusement, some- times in an ardent search for truth. It is only natural that these readers should have been in- fluenced in their directions and modes of thinking by the crys- tallized thoughts of the various authors and since a man's acts are what he thinks, it follows that the Avork done by the readers was enhanced or adversely modified by what they read. Thus we see at a glance how great a responsibility they Avho write assume. The sum total of all science is already existing in this universe, merely awaiting our discovery of it in its affirmative actions. That is proved by the wonderful cosmic jDrogression which is taking place in a definite, unhurried, and absolutely irresistil)le manner, and tends alwa^^s towards a more complete evolution to a higher tyi^e from a lower one. The more complete a realization an author has of this won- derful cosnuc urge, the more valuable in the end will be his writings to his rea- books liaxc been written with an absolute disregard 1o this Inilh, and ol'ten in direct o])position to it, a great many of these books lia\'e been read and accepted by the readers as a guide I'oi- subse(|uen1 thinking and hence actions. Thus the enoi's oT due, ha\-e become the uiisdced of the many, and the misdeeds ol" the nian\- haxc gi'own into a jihigue for the whole. How ol'ten do we liejir the woi'ds, "I should have been earlier, if 1 had not lost in>- wa>'," and how infrequently do Ave I'calize the signiiieaiiec of this ulteranee. Jt is an nbsolutc \';\c\ ili;il uiilold men ;iii(| women liaN'e lost SEQUEXCK OK Til ore I IT 45 their \\a\' on their I'oad to coinpU'le eNolutioii IVoiii a h)\\('i' to a liiglier type, not peiiiiaiieiitly. For that, because of the irre- sistible law of eosniic pro;[;ressioii, is iiii])ossil)le; but foi- tbe time beiii"-, and they will ai'rive, undoubtedly. They will awaken to throw off the i-etardin<;- blanket of mind-disturbing- mental efforts and strike out into the ])road highway of elear undeistanding. They will come under the inlluence of mind- developing mental efforts and they Avill arrive, for can we not recall the sentence, "I shall light a candle of understanding within their hearts," which means that they who have eyes shall see, and they who have ears shall hear! It does not matter iiow many beings are at present in the grasj:) of misunderstanding; that is it does not matter so far as the ultimate result is concerned.- The one regrettal)le fact is that these beings are so to speak in bondage so long as they persist in their course. Ulti- mately they will turn about and reach the destination assigned for humanity which is complete evolution. In the interim, they will have suffered, and will have brought suffering to many. All that, because one man was ])lind and recorded the black of night and called it the ray of light. It is incontroverti])ly true, that idtimately we shall all have a correct understanding of the interdei)endence of all media in the universe, in spite of all the erroneous theories spread by the reading of hy])rid volumes. They shall be forgotten, lost and destroyed by the virulence of the thoughts they called forth, for we see tliat everything in Nature tends ever to a fuller expression of life, and life means completeness, and the full expression of life implies hapjnness, and happiness implies har- mony, and harmony implies order, and order implies projiortion, and proportion implies beauty, and (lest we forget) the will to call forth the mental impression, crystallizing into thoughts on, and of, beautiful things; such thoughts later manifesting them- selves in our respective acts, while calling for both mental and i:)liysical activity, are in no way hurtful or exhausting. Thus we recognize the existence within us of an inexhaust- ible supply of energy to oppose and surmount the deleterious and self-destructive influence of the secondary, though coordi- nate, mind-disturbing and incorrect mental efforts awakened 46 CAST (_;()LI) AND rOF.CEI.AlN JNLAVS by the inhid-disturl)!!!,!;' j)r()])a.i;aii(la of tlic iiiii'ortuiiate auihor.s of misfortune si)rea(liii,i;' thoiiglits. If a more concrete example of tlie influence of reading in rousing ns to mental efforts be required, I would sulnnit for your consideration, the reading of Kipling's "If." It is in- spiring and powerful, and throbs with the essence of truth and purpose and a lofty ideal. It will stir you with its mighty pur- pose for liumanity's growth, and it will awaken within you, mental efforts Avhich will crystallize into thoughts, which thoughts will manifest themselves in your physical acts. You will know more, think more clearly, and work better; and all these enhanced activities, though calling for an apparently in- creased expenditure of both mental and physical effort, will prove in no way hurtful or exhaustive. Again I would submit for your consideration, Tom Moore's "Veiled Prophet of Khorassan." It will rouse you and thrill you, and shake you and wa]<;e you, and almost kill you with its insane emotions of tli(^ insane x)rophet and his benighted fol- lowers. It will rouse you into mental efforts which will crystallize into thoughts, which thoughts will proba])ly manifest themselves ill tiic physical act of your nausea. It will leave you less virile, more fretful, and almost consume you with the fury of your anger at one of thousands who have duped the world's inno- cents, and are still (lu])ing them to the holy tune of "Blessed are 11i('\- lliat know not and believe." A Consideration of the Foregoing Plus Our Ideal of a Task If we read the foregoing carefully and follow the tieiid of the thouglit it expresses, we must realize that usually our thoughts and deeds ai'e 1iiige(l to a great exleiil willi the hues of llie deeds of those that have gone before, and we realize also that in this manner are traits, habits, and usages formed and confirmed. If that were a fixed iMile in the exoliit ionary strife of the cosmos, there would l)e cosmic ]-e])etition instead of cosmic pro- gression, and there would l)e no need whatever to attempt to SEQUENCK OK Tl !()('( ; I IT 47 t'onii a new sjK'clral aspect of tliiiii^s in ^('iici-al, and tliis ])art oL' wliat sliall ))i'()\(> a i-ccrcalivc ai-1 in |>ai'1ic'ular. But tliis is not a i'wvd rule, t'orluiiatcly, and tlio fixity and induent'O of tliis rule, or rat her tcudciicy, vai'ics inversely witli the number of humans that stai1 tlieii- tasks, no niatier what they be, from the standpoint of sim])h' feeling. Now what docs tliis mean? It m(*ans .just this: AVe seek- to express in our work that which we I'eel we would have the work he, and that hrings us to the prohh'in of attempting to i'eel ourselves to be so possessed by our ideal of what we wisli to do, that our aecomi)lisliment of the deed will he a ])hysical manifestation of what our ideal of it was. If the sum total of our efforts in this cosmic certitude he nothing hut a reflection of the mental eiforts, crystallized thoughts, and physical acts of those who were here before us, or even here now, plus the expenditure of a given amount of energy, then the most we can hope for is to make fairly accurate constructionists or analytic scientists of ourselves. But, if we take what we see, hear, touch and read, and care- fully absorb what is thus offered, and then, putting these into the background for a moment, start our task with an ideal of what we wish to accomplish; in other words, if we feel Avliat is required, and we have a conception, an ideal of what the thing that is required must look and act like; that is, if we start our task from the standpoint of simi)le feeding, we have, not only the chance but the assurance, that our work will transcend the scope of simple mechanics, and it will, in truth, become creative. The interdei)endence of all media in the universe makes it essential that we be able to distinguish absolutely between cause and effect; and though an effect may, and usually does, start a train of secondary causation, our ideal of a task must be high enough and its hold upon us nmst be firm enough to enable us to see the mentally conceived, jjliysically manifest itself, devoid of any limiting conditions imposed by outside influences, of what may be an effect of a secondary train of causation. Virtually, that is creation on the level of the human growing in evolutionary definition and degree. For creation is the inception of first life from so))ietJtini/ intangible into something tangible. 48 CAST (iOLU AND roiU'KLAlX IXLAYS SOME RATIONAL AND ACCEPTABLE CONCLUSIONS AVe must iiiiderstaiid and accept in order to understand: Tliat tlie creative effort of the nniversal creative force is, as said before, always toward tlie evolution to a higher type t'l-om a lower one. That Ave as humans, rej^resent within ourselves every step in tlie evolutionary efforts of the creative force in its attemi^t to advance from a lower to a higher type. That since Ave are possessed of the qualities of life, intelli- gence and individual volition, Ave may greatly aid in this ad- A'anee, or Ave may, in a measure, temporarily retard cosmic progression in the human, ])y either doing Avhat Ave should not, or not doing Avhat we should do. That since the creative force is the source of all creation, it follows that no one manifestation of the CA^olutionary effort of the creative force can permanently affect in an ach'^erse man- ner its hiws of growth, tendency, and cosmic 2:>rogTession. That the acknowledgment or the accei:»tance of the theory of evolution does not ai'gue against inception of life in a creatiA^e sense. Tliat since the creative force is the source of all creation, it must 1)(^ the source of all first life upon this, or any other planet. That it is pi-eposterous to assume that any man Avill spend his entire time deA^eloping any sort of Avork Avitli the sole ])ur- pose to ultimately destroy every evidence of his efforts. That it is far more ])reposterous to assume that the creative Uivcc will tolei'ale coiidilioiis wiiicli tend to iiiillilicatiou of any creative effoi-t on lis pari. That the ultiiiialc imipose of llic crenliN-e force is the ])er- fectioii of species which ai-c j)hysical manifestations of its varied activities. That, of all these species, the hunum is the closest relation of the creative force, ])ecause the human ])Ossesses, not only the (juality of a])])i-eciatioii of the creative grandeur, hut also the ])OW('i- of iniilalion ;iiid ini;i.ul!i;i1 ion, ;uh1, 1o a limited extent, r)i-igiiiation oi' creation. That the creative forc(; lias displaxed ujjon a, stupendous scale the faculties of selection and adaptation of means to ends. SEQUKNCH OF Tll()l(;ilT 49 That the hiiiium possesses these i'aeulties to a reinarka])le degree. That the purpose of tlie creative force toward the liumaii species from the iirst inception of its existence has been, and is, that of a gradual, l)ut constant, evolution from lielpless in- efficiency to perfect type. That perfection of tyjjc, to be disi)!ayed ])y the human species, imx)lies a jjerfect equilibrium of perfect organs \vhicli sliall make up the physical body of the human. Tluit wlien tlie tendency of the creative force is toward per- fection of type, that stage Avill ultimately be reached through the aid of the particnlar species itself. That the creative force of the universe is at our disposal in direct proportion as we understand the determined laws of growth, tendency, and cosmic progression, and submit to them in order to transcend them. That perfection of the human species implies the elimina- tion of all disease of mind or body. That it implies also the elimination of all economic or social conditions which make the presence of disease j^ossible. That any individual or conununal tendency of the human species to oppose the general evolutionary progression to per- fect type is effectually counteracted by the creative force, in that it calls forth conditions which overwhelm opposition or the result of opposition. That human misinterpretation of tendency and purpose of the creative force is almost, if not quite, as old as the first spark of intelligence which appeared in the genus homo. That limited intelligence was the cause of this misinter- X) relation. That a misinterpretation is an error. That an error is a hindrance in the ])ath of our evolutionary cosmic progression. That as such, it is in conflict with the tendency of the crea- tive force which inunediately sets about to call forth conditions to overwhelm the result of the error and the cause of it. That hence, the healing art is as old as the first error of man. That errors and accidents are the 2:)rimary causes of all human ills, and all accidents are errors of one kind or another. 50 CAST CorJ) AXD I'OTvrHLAlX INLAWS Tliat all errors arc traceable to the as yet iiieoiuplete evo- lution of the liniiiaii, ])liysically and niciilally. And iinally that the complete evolution of the human, phys- ically and mentally, Avill be attained throuftli the properly directed efforts of the humans themselves, working along and in accord with the universal laws of growth, tendency, and cosmic progression. The healing art is as old as the first error of man. The milestones that mark the important events in its ex- istence are the periodically determined incontrovertible facts, which ^^^ll finally make out of the art of healing the science of health restoration and maintenance. Dentistry is the art of restoring to use and service dete- riorated oral organs and tissues. Dentistry was, and to a large extent still is, a medle,}^ of acts devised by humans to counteract the breaking down of the oral organs and tissues through disease or accident. Dentistrj^ is a jjart of the healing art, and is as old as the first error which resulted in the initial oral or dental deviation from the physiologic, or normal. The milestones tliat mark the important events in its de- velopments are the ])eriodically determined incontrovertible facts, which will finally make out of the art of dentistry, the science of tooth and oral health restoration and maintenance, with emphasis on the maintenance. Millions of the Iminaii species ai-e as yet in the grasp of ills resulting from eri'ors of judgment, and o])])osed to these millions are a handful, wIkj, under veritable inspiration, are doing the woik' of llic creative force in bringing about con- ditions which \\\\\ iil1iiiial('l\' iiiak'c man understand that he is lieaded in the direction ol' evoluting into a ])erfect manifestation of tlie ci-eativc force; that is, of evoluting into that which it feels itself to be, to wit: a creative force. Tlint handful of men, working againsi wind would seem 1o be iiisnrnionnlnhle obsta- cles, Avill be ti-ium])h;iii1 in llie work in whicli they are the fortunate instruments. 11' we redeei for a nionienl. wi' .-hall lind Ihls xci'y simply and very easily j)rov(Ml. We understand that no one nmiiifeslalion of the ci'eative force in the universe. Its vei>- name implies, that and the re- growth, tendency, ;uid cosmic progression. SK(M'I'-N'<' ■I'll on; I IT 51 Wo iin(l(M'Hlaii(l also llial man is oiw of the iiiaiiircstatioiis of the varied activities of thai cicaliNc loree. If we iiiKh'Tslaiitl ihat ev< ii in Ihcir iiiost active periods, liuiiiaii ills can he hut a pail of man, that is hut a ]»art of one ol' the manit'estat ions of 1 he ei-(^ati\(' I'oi-ce, and no ])riiiiary ])art at alh then we must rcari/e how siiiiph- and ])re(lestiiied is the linal eoiKincsi of all inlluenees which would tend to retard coin- ])lete evolution alon.i;-, and in accord ^\itll, the laws of f^'rowth, tendency, and cosmic ])rogrcssioii. Xo one will dis])ute that the creative force is tlie greatest force in the univei'se . Its very name imi^lies tliat, and the re- sults of its efforts sustain that assertion, and it is concrete enough in its manifestation to enal)le even the uniniiiated to become aware of its presence. AVe may even have a very con- crete example to illustrate t1ie final victory for evolution over cosmic repetition. If two forces, acting in opposite directions, exert their efforts upon a movable body, the resultant Avill he the difference between the two forces, and the body will traN'el in the direction of the greater force. If this holds true in sim])le mechanics, how powerfully over- whelming must tinally be the triumph of the creative force in (A'ercoming the effects of human error upon humans. This also ex])lains why it is ])()ssible for a few men to counteract conditions brought al)Out by the acts of untold num- ])ers. The few are working along, and in accord with, the laws of growth, tendency, and cosmic progression of the creative force. It may take a dozen years or a dozen centuries for the cre- ative force to acconqjlish its work, or it may take a thousand centuries. AVho knows ? That the work will be accomplished is as certain as if it were a finished deed at present. The prohlon flxit flx'H n'ho desire in irorl- irifli ilic creative force are face to face icith, is, how can they hest accelerate the luorh of this creative force; and since that problem is vni- versal, the sohifiou iiiKst he one capable of nuiversal application; and this means that if ire are engaged in ajuf liinna)/ error- correcting work, ?re must attempt to so do our work as to make a recurrence of the error impossible, or as nearly ihat as possible. CHAPTER II . THE FUNCTIONS OF THE TEETH The teeth, as organs of incision, jirehension, mastication, and as accessories of A^ocalization, speaking or singing, liave these varied functions to perform. To be best suited for this task, nature lias caused them to accpiire, in the process of their develoi^ment, certain qualities and certain definite structural shapes. Any deviation from their macroscopic normality and their microscopic organization, causes a lack of functional effi- ciency and interferes with their normal contribution toward the maintenance of vital balance. Hence all dental efforts should be directed toward a re-creation of macroscopic and microscopic acceptableness of these organs when they require our attention at all. In health, gums, teeth, in fact all organs in the animal body, perform their function as a matter of grateful exercise without undue consciousness on the j^art of the animal contributing to the maintenance of an efficient organization, in Avhich the income is greater than the expenditure to obtain this income; but, in order to obtain such a condition, there must be perfect inter- play of all organs making up the animal body, and the first requisite for perfect interplay is absolute lack of interference ])y one organ with any other one or more organs. We have had our lectures on anatomy of the teeth, and we know what they look like, or should know. We have had our lectures in physiology, and we know what the gums and the ad- joining structures look like in a healtliy mouth; we have like- wise also been able to learn the beautiful lessons of occlusion. All these should have given us a ])icture of healthy conditions not easily erased. And it is this ])icture we must ever seek to ]-e-create, and we can not re-ci-oate it en viassc unless we re- create it in spots in iii(ii\i(lual tcclli ;iii(l tlieir suri-ounding gingivae. Let me call vour attention to a reniaikable realization, FUNCTIONS 01' Till': TKK'I'H 53 which must come to all of us who wouhl endeavor to obliterate the effects of human error ujjon the human system. Every mol- ecule that makes up the Jiuiiian, or animal, or plant body is in a state of constant rhythmic movement, which motion is in def- inite geometric rehition to the motion of the molecules neigli- l)oring it, which warrants the conclusion that the molecules influence one another by their rhythmic movements to the point of causing corresponding geometric gyrations in each other. This is, of course, not a matter of first causation; that is, not a matter of life incei^tion, l)ut rather a matter of life main- tenance by virtue of the maintenance of the equilibrium. If we conceive the animal as a delicate clock or watch, for example, we may ol)tain a concrete illustration of the interrela- tion of all the organs. Let us assume that we are accelerating the minute hand of a clock hj slowly rotating it to the right (take out your watch and make the example more concrete); we can readily understand that we shall by this act influence the entire mechanism to a more accelerated motion, and that this motion will l)e in definite relation to the intensity of the acceler- ator force, and that there will he a definite rhythmic and geo- metric relation between the motion of each sej^arate piece of mechanism which makes up the whole of the clock. If we remove the influence of the accelerator force, an inmiediate rhythmic and geometric adjustment takes jjlace, and the hands of the clock jDroceed to travel at the original speed. This may be called a stimulating interference with the mech- anism, and results in a greater amount of work or activity being done in a given time than the api^aratus was intended for. If we now place the hour hand at the numeral 9 and the minute hand at the numeral o and susjijcnd a minute weight from the extremity of the hour hand, we shall have an inhibitory inter- ference with the mechanism, resulting in a given amount of energy doing a smaller amount of the work than the apparatus was intended for; the spring will uncoil or attemj^t to uncoil at the same ratio, ])ut its effect ujDon the wheels, and through these upon the hands, will be less marked than before; again there will be a rhythmic and geometric readjustment to normal when the inhibitory interference is removed. Up to a certain point, tliese ex2:)eriments may be re23eated 54 CAST GOLD AXI) POKCKT.AIX IXLAYS Nxitliout iiii])airiii,i;- Uw iiilu'i'dit \irility oT llic s])i-iii,i;', l)ut as soon as tlie ])(>int of i]iii)ain)ieiit is reaeluMl, a rlivtliiiiic ix>- adjiistineiit becomes impossible, a lack of loerfect iiiter})laY man- ifests itself, resultiii,2," in a lieedlessjiess of expression; tlie ])ai1s interfere with one another, and a ,2,reat deal of energy is ex- l)ended to In'ini;- al)ont a result; work Avliicli is as nnsatisfactoi\v as it is nnreliabk\ For the j^ui'ijose of elimination of mechanical shock to the iiervons system during- mastication, and for the purpose of en- hancing the vibrating effect produced during vocalization, be it singing or speaking, also for the purpose of minimizing me- chanical injury to the teeth themselves, the latter are held in their bonj' sockets througli tlie intermediary agency of an elas- tic membrane, which is so disposed beneath and around them, as to fairly hold them suspended in a resilient cushion. The elastic fibers comjoosing the membrane dispose them- selves longitudinally, diagonally, transversely, and circularly around the teeth; they interlace with the periosteum and with the gum tissue, and thus during the exercise of dental function they effect an increase of circulation into the surrounding i)arts, which constantly brings fresh nourishment to these tissues. The vei-y structure of this elastic m(Mnl)rane and its pecu- liar function precludes the jjossibility of abundant blood supply and makes it a ready prey to inhibitory interference. Such in-^ hibitory intcM'ference may be brought about by impaction of foods into what are known as intei'dcntal s])aces or by the ac- eumulatiou of cah-ilic matei'ial known as laitai", either ujjon or ai'ound the neck of the tooth, or upon ])ortions of the I'oot. The impaction of food into the intcrdcnlal spaces may be caused by the malrelation of tlic adjoining teclh (niahx-chision) or by the ini])i'ojjei- restoration oF appi'oximal suiTaces of tcctli calling for dental attention. An inhibitory interference may also 1)C brought about by a bicak in the continuity of sui'face upon a tooth in the region mentioned. A tooth nia>' be inla_\(Ml and a ])ortion of the inlay material may haxc Ix en left e\t<'nding Ix'yond the mmgin of the cavity. if |)|-e,-snre he exerted npon an\- one or two teeth ill the mouth, the pressure will he t raii.-inil ted in ;ill the siirroiiiiding structur(_'S, and throii'ih them to all other teeth in Ihe same FUNCTIONS 01' Tin; TKILTII 00 iiioiilh ill a scries of I'liyiliinic waves or iiiKliilations of \'ar\'iii;i,' degrees, cliaii,i;iiii;' llic physical oiilliiic of the siinoiiiKliiii;- stiTic- tures ill every direction. r])oii the cessation of tlie j)ressure a rliytlimic and geometric ri'adjustiiiciit ^vill take jilace in these tissnes and a return to a condition of c()iii|)arative equi]il)riuni ohtaiiis. Where there are no inhibitory iiiterrei-ences, tliat is ^vhel•e the rehition of the teeth is correct, as to position, con- dition and form, these pressure-induced waves or undulations may take phice ad infiniium. witli beneficial results, because un- der a correct coiidifio)/, iiifcriniltoif })rcssiire is tJte essential sfiiiiul((tii/f/ iufcrfcrcncc i)ifl nciur/ tni nicrcase of circulation, Jjriiigiug wiilt it a frcsJi siipijl/j of Hufriiiient essential to life maintenance. AVhen inliibitory iiiterrerciices are jiresent, that is, wlieii the relation of the teeth is not correct as to position, condition, and form, each pressure exerted upon the teetli during mastication causes the same series of waves or undulations in the soft tissues surrounding them, but each wave or undulation causes these tis- sues to come in contact with injui-ing or l)ruising obstructions, and the rhythm of recoil or readjustment is first interfered with and ultimately destroyed. Poorly executed inlay restorations may ])e classed as in- hibitory interferences with the free and unliam])ere(l undulating and very essential excursions of the soft tissues surrounding the teeth. They produce states not conducive to the health of the individual, and are, therefore, incorrect dental conditions; and any dental o])e ration that will entirely eliminate them will be an operation conduci\e to the health of the individual, and, therefore, a correct dental oi)eration. All tissues must be exercised, or, rather, they must have the freedom to in\' a lask wlien oui" task consists in an elforl lo balance income ;ind e.\|)endilnre of human eneig-y, and it will e\'ei' l)e so, no nialter liow we may improve our relations between oui- vegelativ(; and objective !•' UNCTIONS OF THI-: TEETIL 57 litV, or Jiow inurli we may learn ol' llie mysteries of the bio- cliemical life processes tliemselves. It is e(|iiall> true that constant effort for correct inuler- slaii(liii<;' of these things must r(^sult in improved conditions, \vliicli \\\\\ enable us to husband the jiow vastly dissipated energy, and so prolong our activities and usefulness to a con- stantly glowing degree. Intuitively we are all aware that this is true, tiie l)est jji'oof of it b(Mng that we are in constant search for means of so improving remedial efforts for our jjatients, that they, the efforts, will result in a harmonious interplay of the intact functionating organs and the artificial work. AVe nmst. therefore, face the self-evident proposition, that the cruder our remedial efforts are, whatever organ we may he working upon, whatever our sphere of activity, whether it he general medicine, surgery, or the specialized field of dentistry, and all its kindred divisions, the less acceptable will the results be to the other functioning organs; this means innnediate rebel- lion on their i:)art; and, unless the cause he removed, must result in a physical state which is physiologically minus and patholog- ically plus: conversely, the more finished or refined our efforts are, the more acceptable will the results he to the other function- ing organs. A finished or refined, remedial effort, in hehalf of any organ, imijlies a knowledge of its individual and relative anatomy or physical relationship, and a comi^rehensive understanding of the physiologic functions of that organ. This brings us up to the affirmation that teeth have func- tions (plural used advisedly) and a careful enumeration and a critical classification of these functions are now in order. AVe may now record the trutli that the so-called masticatory apparatus is not a separate, distinct, and independent part of the human organism, hut a functioning nmltiple member, or cog, of a very complex microcosm, in the maintenance and pres- ervation of which it plays a very important part. The so-callod masticatory api:)aratus is not a simple functioning member of this complex machine, ])ut is, in itself, a very complex com- ])onent, in that it comprises many organs diversely endowed with si^ecialization. The thing that sug<2-ests itself first in mv mind in regard 58 CAST COJ.D AXD POECELAIX INLAYS to tooth J'liiu'tioii is the rcciijrocat i'uiictioiis of the teeth; reeij)- rocal becaii>;e they do some things for the orgaiiisiu whieh does some things for them. Since every oi'gan of the body i^assiveiy and actively ex- ereisCvS sncli functions, these may be called the reciprocal f mic- tions, and nnist l)e classified as tlie jnissivc and (ictlve reciprocdl fnnctious of the special organs. PASSIVE RECIPROCAL FUNCTIONS The jjassive reciprocal functions of the teeth are defensive, cosmetic, developmental, and j^honetic. (See Fig. 1.) The defensive functions depend upon the gross anatonty of the teetli; that is, they are so shaped as to prevent injury to the soft tissues surrounding and supiDorting them. Tlie cosmetic functions depend upon the gross anatomy, geometric liarniony, and the Inocliemisr}^, of the teeth. They must be in harmony with other features of tlie face, and, by correct growth, inlluence the other features of the face to har- mony, thus also partly exercising the developmental function. The pJionrfic functions depend upon the gross and niicro- scojnc anatomy of the teeth and their position relative to each otlier. That is, they nmst not only be of a shape and relation conducive to clear enunciation, but also of a texture insuring tlie proper degree of resonance and vi])ration. The latter part of this function we can unfortunately not restore by artificial means. ACTIVE RECIPROCAL FUNCTIONS The active reciprocal functions of the teeth nnist he I'ui-ther classified into general and special. The fpnteral functions are cardioauxiliary or vasoauxiliary, and syjn])toniatie. The cardioaaxiliarji mi- rasodH.riJidi// finiclio)! consists in tlie restimulating effect, wlilcli the iiiohilil >• of the teeth has upon the circnhil ion (>[ the slrnclnres in w iiich the)' are, and with which tiiey are resilient 1> Joineth \)\ \irlu<' of ihis niohililx, lhe>- in(hice a rlixthniic inter- mittent pressure which, inimical to mid tissue stasis, hi'ings I-'UXCTIOXS OF TIIK TKKril 59 £.CTICsJb) DCFENSlVt Passi Reciprocal Ti. L (.Ex. fir EnPOCE^ous) £ g Incision Fiy. 1. — Diagram ishuw iiiy reciprocal functions of the tcetli. GO CAST GOLD AND POECELATISr INLAYS about a constant cliange of the nutrient elements traversing the nutrient channels of these tissnes. The symptomaiic fiuictions nmst be subdivided into struc- tural and positional. The structural dyinptoinaiic fuitctiotis may be indicaitve of some congenital or acquired constitutional anomaly; such as, Hutchinson's teeth, thyroidal disbalance (as illustrated in teeth easily attacked by caries), or in the presence of a marked pro- creative urge, often bordering on lack of sexual equilibrium, as illustrated in canines of decided prominence and marked pre- hensile formation, reflecting, perhaps, the animalistic trend of the individual in whom very freciuently also are to be found small suin-arenal bodies with narrow cortex, demonstrating, perhaps, a greater procreative and a less intellectual mission in the cosmic scheme. The positional sijmpfouuitic functions deal with the mal- position of clitferent teeth in the maxil^ and mandible, and are valuable diagnostic determinators in that they thus unerringly point to pituitary, gonadial, thyroidal, and adrenal disturbances which would otherwise be most obscure. The special active reciprocal functions of the teeth are coiiinmnal and individual. The communal special reciprocal functions of the teeth are alimentary and inhibitory. The alimentary functions consist in the x^art they all play in the prepai-ation of certain foods for the process of digestion. The inliihiiori) jiiuctions consist in the physical relation- sliijj of the teeth ov their I'elative apposition mesio-distally in ])articular, so as to retard, or limit, the latei-oi'otary motion they ae(|uire when in use. The individual (unctions are those of incision, jirehension, mastication, and tiituration, and, in the sequence enumerated, involve the incisoj-s, canines, bicus])ids, and inolais. Since all functions are recriprocal, there can be no hxed lulc or line of demarcation as to wJiere one stojjs and the other begins. All these enumerated, classified and dissected, present them- selves vividly at some j)oint, the height of the j)ai-ticulai- func- ri'XCTJONS OF TIIK TKKTH ()1 tioual expression, to gracefully and gradually merge or lose themselves in those which follow. Thus we have an interplay of j)arts devoid of harsh or interruptive demarcations. A pleasing harmony as expressed in coordinate effort, salubrious in effect; a song of work as marvelously planned as it is symphonically exi)ressed in Jiving- ness,i and yet more livingness, to the glory of the mind that l)ade it come into being. SUMMARY FOR CHAPTER II The Functions of the Teeth 1. What is meant by the reciprocal functions? 2. How are the reciprocal functions classified? 3. Xanie the passive reciprocal functions and define each. 4. How are the active reciprocal functions classified? 5. Define the cardioaxiliary or vasoauxiliary functions. 6. Subdivide and define the symptomatic functions. 7. Define the following functions: communal, alimentary, inhibitory, in- dividual. CHAPTER III THE CAST COLD INLAY Human teeth decay and become a source of discomfort and dano-er unless tliey can be restored by tlierai^eutic, operative, and iiieclianical means. The foregoing is a statement of facts that no amount of argument can dislodge. It is universally known, so far as our l^rofession is concerned, and it stands as a comprehensive reason for our entii-e and particular field of endeavor. It, therefore, presents a proper basis or fundamental statement for this volume, although this volume concerns itself with only that part of corrective endeavor known as inlay work or the cemented filling. This work, that is, the restoration of a broken-down tooth by means of a cast gold inlay, may be broadly defined as a den^ tal operation. Any operation may be correct or incorrect; and a correct dental operation may be defined as one, the result of which is conducive to the health of the individual uijon whom the opera- tion is performed. We understand by the term health, the main- tenance of that vital balance which is expressed by the normal functioning of all organs which comi)ose the human body. Inlay work may be divided into two classes, metallic and iioninclallic. Metallic inlays, wliidi, hccausc of llicii- iiiij)ortance as tooth- restorers, shall liaxc lii-sl jilace, arc those that ai'e made of gold or any allo\ in which gold or other suitable metal pre- dominates. The making of metallic inlays may be brought about by the swaging or casting method. The foi-mer are so imperfect and have proved so unsatisfactoi-y that they are becoming obsolete ;in(l will not he considered; ami since gold, as a rule, ])i'e(lonii- nates in the cast inctallic itila\-, it will liereal'lei' he rerci-rcd to as ^lie cast (jold liildij. 02 CAST COM) IXI.AV 03 yl cdsl f/i>l'l nihljl liKljl he f/c/ilirfl (is ii iiidss oj uioltcH iiicfdl Hi/dcr (Ic/ii/ilc f/asfous pi'cs.'^iirc, forced ii/lo (iiul sliapcd in a special nudd, so lliaf ll iiill , upon cooliiifi oy cri/.staUlzinfj, accurately fit into the earilif of Ihc loolh from ii-lilcli the wax pattern emt)edded In the mold n'ds lahcn, and iJiat cool mass of metal sliati in outline and eminences so conform to the out- lines, and eminences of that particular tooth, and opposincj and adjoining teeth, if there he any, that it shall form an acceptable, anatomic, complement to the tooth requiring restoration, and It shall mal-e that tooth macroscoplcally perfect. In short, then, a ca^st gold inlay is an accurate metallic complement to tJie macroscopic anatomy of a hroken-doivn tooth. The process of restoring broken-down teeth by means of cast gohl inlays consists of a series of stejis or operations which in tlieir proper seqnence may be enumerated in tlie fodowing order : 1. Selection or election of the case. 2. Prei)arati()n of tht^ cavity. 3. Selection of the proper wax and the making and carving of the wax model ])y means of the direct or indirect method. •i. Taking an imi)ression of the cavit}^ aiid making a die for i:)rocednre ])y the indirect method. 5. Selection of tlie refractory compound and tlie iml)edding of the wax model to construct the mold. (). Drying out of the mold, and the l)urning out of the wax iikmU'I. 7. Casting of the molten metal into the mold. 8. Cleansing of the casting in hy droit uoric acid and in a so- dium l)icarl)onate l)ath. 9. Tvemoval of the sprue, forming excess gold, and the polishing of the inlay. 10. Cementation of the inla5\ SUMMAHY FOR CHAPTER III The Cast Gold Inlay 1. Cliissifv inlay Avork. 2. What iiu'tal is most suital)le for inlay casting? ;_>. What is tlie function of a cast g'ohl inlay? 4. What aro tlio st(>i)s (in their pi'oper sequence) that are Tiecessary to proiluee a cast t^'ohl inlay. CHAPTER IV SELECTION OR ELECTION OF THE CASE PRESENTING A CAVITY (A) Any tooth distally to the disto-proximal surface of tlie canines, requiring- a gohl hlling, can he restored more perfectly l)y means of a cast gohl inlay. (B) Any lahio- or linguo-gingival cavity hrrger in diameter than o nnn. distally to tlie second bicuspid calls for a restora- tion by means of an inlay rather than a malleted filling. (C) Any tooth requiring restoration of proximal contax:^t calls for an inlay rather than a malleted filling. (D) Any tooth requiring occlusal restoration in its relation to opposing teeth calls most emphatically for a cast gold inlay in preference to a malleted gold foil filling. (E) Any compound cavity in any tooth, distally to the first bicuspid, calling for a gold restoration, indicates the use of an inlay rather than a malleted filling. (F) Every mesio-disto-occlusal cavity in any multicuspid tooth, should be filled ])y means of an inlay rather than a mal- leted gold foil filling. The gold inlay is conl laindicated in: (a) Small proximal cavities in the anterior teeth. (b) Small fissure cavities in anterior teeth lingually and, (c) Small cavities in posterior teeth occlusally, (d) Small labial cavities in posterior teeth in mouths com- paratively iiiiiiiiiiic 1o |)i-ogr('ss of decay. SUMMARY rOR CHAPTER IV Selection or Election of the Case Presenting a Cavity. 1. Xamc the types of cavities when a cast ^old inlny is indicntciL 2. Tn whaf eases is the inlnv contrainrlicatcd ' 64 CIIAI'TKIJ \' C'A\'1TY JMii:PAIJA^ri()X GEOMETRIC LANDMARKS OF TEETH Tooth Surfaces and Angles I^A'ery incisoi' tooth jircsents for exaiiiiiialioii four distinct surraces; a cutting', oi- incisal edge, and a nuiiilxT of line and point angles as follows: (See {Fig. 2.) SriiFAC'Hs OF Ixcisoit Tfktji Mesml (1) Distal (2) Lahial (3) Lingual (-!:) A distinct incisal surface at times (5) AXGLES OF IxcisoR Tp:ETn Line Aiu/lcs Alesiodahial (()) ^lesio-lingual (7) Disto-labial (8) Disto-lingual (9) Cuffiiiff, or Point, ^iiif/Ies Mesio-lal)io-incisal (10) Disto-la])io-ineisal (11) Mesiodinguo-incisal (12) Disto-liiiguo-incisal ( 13) In incisors having a distinct incisal surface, the following line angles must be added. Line Angles La])io-incisal (14) Linguo-incisal (15) Mesio-incisal (16) Disto-incisal (17) 65 66 CAST l;0L1) AXD POIK'ET.AIX INLAYS tX3 S -, t-. - =5 is> so ■^ ao b^ ■*- 1 \ \ »o \ 1 \. _ \ 7-1 K> S \d -^\ / --\ \ y ~^"~ — V ^•*. ^ \ O ^ v/ \ 1 , oj— ^^ ^ \ 1 ^ >'r- Cvi •2»^ ^ S "a^ 5 rt .^ r- or « .^ ■^ ^ c. ^ bt 'T N,; ■5 ■^, C/J +3 05 CO >. '2 bi 03 O! h rt bXI C tJ3 « >5. *«. \ \ C o o 7:1 bij =*H be ■♦^ ^ bJD ^' ~ rt ^ -M o CAVITY niEPAItATloX (u '^riic cuspids, Upper -Awd lower, pi-cscnl I'oi' cxaniiuatiou four, aud lart'ly live, disliud suiTacos, a teariu;;' i)()inl, or <'us]), winch latter is soiuetiiucs i-e])laced hy a cuttiu;;' ed^c oi- a distinct iiK'isal, or, bettor, prehensile surface. (See Fi^-. :!.) SnU'Aciis OF CrsiMDs Mesial (1) Distal (2) ]jiii^-ual (.''>) Jjahial {4-), soiuetiiues hi-okeu l)y the labial ridge into fjabio-nu sial and (5), Lal)io-distal surfaces (G) AxGLES OF Cuspids Line Angles Mesio-lahial (7) Mesio-liugual (8) ])istodiiioual (9) Disto4abial (10), and very often the labial angle (11), formed by the uiesio-lal)ial and disto-labial surfaces, and when there is a distinct prehensile surface, there are the line angles of the Lahio-prehensile (12) Linguo-prehensile (13) Mesio-prehensile (14) Disto-j^rehensile (IT)) Line Angles ]\[esio-lal)io-prehensile (K)) Mesio-linguo-prehensile (17) Disto-labio-jn-ehensile (18) Disto-linguo-i^rehensile (19), and, at the cusj) extremity, the Lahio-linguo-prehensile (20), point angle formed by the labial, the lingual surfaces, and the prehensile surface of tlie tooth. And when the labial ridge is present in a cuspid, the last named point angle may be referred to as tlu' antero-labio-incisal, or prehensile (21 ), and post(M-o-la1)io-incisal, or prehensile, angle of the cusx:^^ (22). (J8 CAST COM) \NI' POIICKI.AIX |.\I.A^•S With tiic apprin'aiicc of a disliiict iiicisal oi- jjrclicii^-ilc sur- faces circuiiiscril)iii,L;' the pi-chciisilc surface for its entire extent, the ])rchensih' s\i)-face assumes the sliapc of an ellipse, line angles only, present themselves, and we lia\-e the mesial and ilistal arcs t'orniod by the mesial, lahial, lin,uTial, and distal sur- faces eircumsci'ibin<;- the jDrelieusile surface for its entire extent. The bicuspids and molars present for tlie inlay worker live surfaces as folloAvs: (See Fi,^•. 4.) Sun FACES or l>jcrspii).s Mesial (1) Distal (•2) Buccal (13) Lingual (-f) Occlusal {7)) Tlie occlusal surfaces of the bicuspids and molars are sub- divided into twice as many smaller surfaces as tlie cusi)ids have ridges, each ridge dividing the surface of the cus]) ujjon which it presents itself into two surfaces; the number of line angles and jyo'iut angles i)res(Mit in these teeth is, therefore, corres])ond- ingly increased. If the occlusal surface is considered as an intei'ru])ted hoi'- izontal sni-face, the line angles in the bicus2:)ids and molars ai-e, according to Black (who, by the way, treats tliis surface only as such), as follows: Angles or iJici'si'ins and MolaPuS Line Angles Mesio-huccal ((i) ])isto-l)Uccal (7) Mesio-lingual (8) Disto-liiigual (!)) Mesio-occlu>al ( 10) ])isto-ocelusal (II) Bucco-occlusal (12) ijinguo-occlusal ( K!) C'AVITV J'KKl'AUA'l iOX ()!' Point An files Mesio-l)iicco-occliisal (14) Disto-bucco-occliisal ( 1 .")) Mesio-liiift'iio-occhisal (Hi) Disto-liii^iio-occlusal (17) It iiii,i;lit 1)(' well to rciiu iiihci- that in this .ncoiiicti-ic ft'oo^'ra- pliy, we ai-c much closer to s])herical tliau just i)Uiiii ^-eoinetry, and so the refei-ence to eacli surface as distinct hy, and foi-, it- self, and llic con-espondiiii;- an<;le (sui't'ace angles) need not l)e dwelt upon. It is l)est to consider tlie suid'aces of these teeth as iner^in^- into one another ])resentinft' no liarsh or shar]) deviations which are always weak ])oints ])otli in heauty and construction. The exception to this fore^oin*;-, is the occlusal surface of tlie posterior teeth. Here tlie division of this surface by the various ridges jn'esentin"' themselves upon their respective cusps nuist he distinct and well detined, ])roducinf;' eminences, sulci, and fossa' in contradistinction to the undulations ])resent ui)on the other surfaces of these teeth. HYGIENIC LANDMARKS OF THE TEETH The inlay worker must consider two distinct areas in each tooth: First: Tlie immune, or comparatively inmiune, area. Second: Susceptible area. The innnune area of a tooth is that pai't of it which is constantly bein<;- cleaned and kept free from de))ris by incision, l)reliension, mastication, and trituration, or )jy the action of lips, cheeks, tongue and toothbrush. The susceptiljle areas are the i)ortions of the teeth not so cleaned; in other woi'ds, the portions inaccessihle to cleansing- friction by the agents named. Among the former, or comijaratively innnune areas, may be mentioned the lal)ial, lingual, and incisal surfaces of the an- terior teeth: the buccal, lingual, and the welling ])orti()ns of the occlusal surfaces of the j)osterior teeth; and, in mouths free from ])athol()gically inxaded ahcoli, the gillgi^•al and subgingival cir- cumference. 70 CAST COLD AXD PORCELAIX IXI.AYS To the siis(H'i)til)lt' areas l)elo]i,<;' the ])roxiiiial surfaces of the teeth, llie distal surfaces of the last molars, and the gingival third of the buccal surfaces of the last molars; the deep sulci, fosstp, and fissures upon the occlusal surfaces of the posterior teeth; the deep fissures on tlie lingual surfaces of anterior teeth; and, in cases subject to pathologic invasion of the alveoli, and the consequent breaking of the last named structure, all gingival and subgingival surfaces open to contact with fer- mentation and not easily dislodged food debris. (Figs. 5, 6, and 7.) ' -2, J \ Fig. 5. Fig. 6. Fig. ~). — Sliiiwin^i iiimuiiic .'iifas of aiitcrioi' tcctli am! Misi'('|itilile areas. Iiii- niiiiio aroHs: 1, Jahial .surface; ; 2, lingua! .suifacf; .'!, iiicisal sinfacf. Susccjitihlo aroa.s: 4, di.sto-proximal surface; 5, mesio-pioxiinal surface; (i, ccivical |i(irti(iii of labial surface. Fig. n. — Iiniiiuiic ar.-as of jiostcrior tcctli. I, '2, '■'>, t, welling |i(iitiAr.Ai-i<)X of lool work and his- toh)gy are p;irt of 1 he enihryo ol' know led i^i- which he who won Id practice inlay work, nin>1 possos hiniselfor. J*iei',-(»|j Scharer, or \oyes, on the liis1oloL;y ol' the leetli, ('.\^■|'^^■ i'i;i:i'.\i;.\'ri()X I'.l \\\\\ ,i;i\(' the stiidctil a mass of n'ci'N' iicccssarN' and \'('i\v pcr- liiictit iiiroi-iiiation. Anion,!;' llic inst i-unicnts of tlic inlay woi-kci- must be iii- (•lu(l<'(l: ('()inpi-( licnsivc set of cliiscls, — sti'ai<^lit, ri^-lil and left, at varying' oWlusc angles, to facilitate cutting' of <;iiif;ival areas; ])ear-slia])(Ml and inverted cone l)ui'rs; and vai-ious file-cut inlay ])urrs foi- sli-ai,i;hl handj)iece and coiiti'a-an^le; mandrils foi- carryiii<;' sand|)aj)i'r discs and cai'hoi'undum discs for both; and most important, a set of small ^cm stones mounted n])on man- drils for botli liand|)i( ces, and a vai'iety of sliajjes to till every possible reciuirement. Fissure burrs, ci'oss-cut oi" ])lain, ])lu,ii,-slia])ed and ta])ei"(Ml, may be added to complete tJie sni'^ical and mechanical abi'asive instrument list for cavity preparation. The necessity for the rn])ber dam and clam)) is manifest when the saliva interferes with (dean, ra])i(l work. The .general rules for tooth cuttin,ii,' may be enumerated as follows: All ovei-han,L;in,i;' enamel walls must Ix' removed with the properly inclined chisels, drivini by direct hand pressnre or a leather covered metallic mallet. The oi)eninft' of cavities innst l)e started with sharp l)nrrs, ])lu<;-sliaped or cross-cut tajiered fissure burrs of the smallest size suitable. As soon as the cavity is large enough to jjermit the nsing of a gem stone, the use of steel burrs nuist ])e discontinued and the stones sul)stituted. At no time of tlie o])eration shall tlie tooth be allowed to lieat up, and with this end in view, all stones used in cavity cutting are lun under Avater. The margins are chiseled and then linished witli sandpaper and cuttlefish discs. A cavity in a tooth can not be jiroperly prejjared unless that tooth and the teeth adjoining it, if there be any, liave been thoroughly cleansed of any deposits which may be j)resent; and if the cavity extends beneatli the boi'der of the gingival line, un- less the gum has ))een carefully but effectually displaced from the li(dd of o])eration. Scalers for the remo\al of de])()sits and jjoi'te-polishei's. 74 CAST (iOLD AXn rOllt'ELAlX INIAYS carrxiiii;' liiu'l}' powcU'i'cil ])iiini('c' stone or sile'X, ^\■ill accoiiijjlisli the first ])art of the oi)eratioii; \\\\i\o the displaeeineiit of ^'uni tissue is readily brought about by packing tlie cavity Avitli soft- ened gutta-percha l)ase ijlate, and leaving that in the cavity for a few days. The case presenting itself again, the base plate is softened l)y means of warm instruments and removed. A compreJiensive view of the field of operation will aid us in dettrmiuing just what instruments we shall have to employ in the actual preparation of the cavity we are about to l)egin. The inlay worker recognizes three distinct types of cavities; they are, tiic simple, the compound, and the complex. Yv'. 9. Fi"-. 10. Fiy. !).— Cro.ss HcctiDii of iiuilai- lootli iilust I'atin^- |irc]iar('il cavily and bc\cl. 1, 2, 3, cavity and bevel; 4, 5, (i, arms and l)ody of pulp. SinipU' t-avify. Fig. 10. — Cro.ss section of inolar showing- a disto-occlusal cavity. 1, hcvol upon occlusal surface; 2, inclined plane offeriiifi' i)()werful resistance to displace- ment; 3, flat poiti<:n of ;;iii^i\al srat ; -I, 1m'\c1ci1 p;il, caxit ics. .\ eoinponnd ciixilN- is one wliicli involves nioi'e Ihan one, and ina\' in\'oi\e all bnl one, snrl'acc of llie loolli. CAVITY I'KKrAltATlOX i '^riicrc ai-(' as ('xam])los of coiiijjouikI caNilies: 1. Tlic iiiesio-occlusal -. 'I'lic (listo-occliisal 1). The in('si()-la))i()-o('('lnsal 4. The disto-lahio-occlusal 5. The niesio-hi))ial (). The mesio-liiiftual 7. Tlie tlisto-hil)ial 8. Tlie disto-liii^ual 9. Tlie lal)i()-oc'('liisal 10. The liiiouo-occlusal 11. The lahio-oecluso-liiigiial 12. The mesio-occ'luso-distal, or what is known as the ]\[. O. 1). cavity. A complex cavity is one that takes np at least a part of every surface of a tootli, and as an example may ))e mentioned, A mesio-labio-lin<^uo-occlnso-distal cavity. The surgical work in the preparation of simple cavities con- sists, outside of root treatment and elimination of impeding gum tissue, merely in the laying open of the cavity area and the chiseling of the surrounding walls. The mechanical or formative part of the work consists in stoning the walls and floor of the cavity in such a manner that it will conform in curvature to the curve of the surface upon which it is j^resent. The surrounding walls may be stoned so that for two-thirds of their deptli they shall he perjoendicular to the cavo surface, and the remaining third of the surrounding walls nearest the or- ifice of the cavity may deviate from the jDerpendicular and di- verge to form an angle of 30 to 45 degrees. The alterative part of the work consists in so completing the prej^aration that it will present a sightly and pleasing and lasting result, properly protecting the enamel, that it will bring all the margins into areas of comparative immunity, and thus pi'esent a restomtioii most acceptable to the surrounding tis- sues, and hence conducive to the utmost conservation of the tooth. In com})oun(l and complex cavities, the alterative part of the preparation concerns itself with the i)roi)er amount of se])a- <() CAST (lol.D ANIi rollCl'.LAI X 1XI.A\S ration rcM|uii-iMl (wlicii any is rccjuiin d ), and w illi tlic restoration of wliat may he callccl tin' ncclnsaJ Ixihiucc. AVe must ))ear in mind tliat the occlusal surface of tlie ])()s- torior teeth serves, not only in the function of mastication and trituration, but hy virtue of its peculiar formation at the mesio- and disto-oeclusar lines, respectively, prevents the crowding' of tlie food into tlie interdental spaces with an efficiency in propor- tion to tlie correct formation of the points indicated. In other words, the occlusal surfaces of these teeth has more than one function; that of mastication and trituration of food, and that of the prevention of the crowding of food into the interdental spaces. A great many cases of so-called pyorrhea and other gin- gival lesions, mav he traced directly to poorly executed occlu- sal restoration; and when we realize this, Ave shall conclude that these surfaces must be treated with as great, if not greater, care than any othei- tooth surface in the oral cavity. A poorly ]-f stored occlusal surface may tlii'ow the entire face out of balance, and so become the cause of a case of mal- occlusion, which ma}' entail months or years of unremitting effort to correct. This brings us face to face with the realization that only l)y means of the cast inla>' is a pei'fc ct occlusal restoration pos- sible. CAVITY PREPARATION The lex cavities, consists in the cleansing of the held of ()])era- tion, and its sui'roundings, of the chiseling away of the ovei'- Inuiging walls in sneli a inann(M- that no niisn|)|)orte(l enamel walls he lel't standing. I'lie margins ai'e so prepared thai no short enaincd I'ods present any feathei- ('(jgc for thf inln>- to I'rict ionall\' ])lay again>t. H' tin- margin of deslrnelion Icrininale- in a (hep sul- cus of IIm- occlnsal sui'l'ace of a tooth, then the caNit)' must he <*xtend('(| >i) that the maigins of i1, a1 llial point, are cari-ied into, and Ix-yond the sulcus onto the ascending portion of the CAVrrv I'llKI'AKA'I'lOX it cusp. Tlic sulcus is then r('|)|-()(luc(M| In llic wax inlay, 1o he sul)S('([U('iil ly (luplicalcij in llic uold. n'lu' cuanicl seal of the inla\' should he as hroad aud cx- l(Misi\-(' as j)()ssil)l(', and willi that cud in \ic\v, llic l)c\-cl butt joint is used. In tcclh prcscutiu^- a li\"c pul]), the location of tliis or^-an must more oi- less dctcimiiic the extent of l)otli sur^^icai and mechanical oi' roi-malivc work to he done on and in the cavity. AVheu no ])ulps are in'esent, the pulj) canals and chamliei' must co]ne in Tor their share of tlie surgical attention, in that the former are i)roper]3' hlled, and the coronal i:)art so cut as to form Hat and variously slantino- substantial seats for the inlay. It is the mechanical, or foi'mative, part of the woi'k that comes in for very careful attention and for considerable study. The direction of the stress, which the joarticular tooth is called u])on to withstand, should lar^'ely determine the form of cavity which we shall ])re])are for an iiday. As a broad and general rule, the following may be considei-ed: The frictionah or contact relation which exists between a tooth and the inlay made for it, should be, at least half again as large as that part of the iiday which will be called upon to enter into stress relation with the oj)])osing teeth and surround- ing tissues. This applies to all cavities and most particularly to com- j)Ound and complex cavities, and in these latter cavities, the rule luay be elucidated as follows: the more of an inlay inside the tooth, and the less of an inlay outside the tooth, the less chance for sui-gical or mechanical injury to that tooth. Please note the his'ide of the tooth and outside of the tooth, and do not confuse with on or (diore the tooth. An inlay may be made for a tooth, aud it may present or restore the entire occlusal surface of that tooth, and so ex^wse a very extensive area to stress relation with the opposing teeth, and the area of frictional relation between this cavity and this inlay may seem to be smaller in extent than the area exjiosed to stress. These inlays must be considered as resting in a box seat; in other words, the cavity is one presenting the apix'arance of a simple one in every surface but the floor; here is found a devia- tit)n in that floor, instead of conforming in shape to the sur- 78 CAST (lOLI) AXl) PORCEI.AIX IXLAYS face 111)011 wliicli it presents, slopes to l)eeoiiie an inclined plane to offer the reqnired resistance to displacement dnriiio- stress of mastication. The incline slionld be sharp and well defined; a step may ])e nsed, hnt an incline tends to l)etter conservation of the tooth. In teeth snl)ject to stress, from and in more than one di- rection, these lines of stress must be carefully studied, and an inclined plane must be formed upon the floor of the cavity to o])i)ose each line of direction of stress. In cases where the cusps are very deep, and where the man- (lil)le enjoys a limited laterorotary motion, thus subjecting the molar teeth to a considerably greater amount of laterorotary stress than Avould be the case if the motion of the mandible were Fig. 11. Fiff. 12. Fig. 11. — Longitudinal .section of molar, at 1 and 2, jncsial and distal planes, re.spoetivoly, witli apex at ?>. Note correspondence of incline in planes and bevels at 4 and 5. Planes and bevels are practical! parallel. Complex cavity. Fig. 12. — Cross section of bicuspid showing (1) occluso-disto-lingual plane and (2) occluso-mesio-lniccal pliiiic Complex cavity. very free in lliaf dii'cciioii, the Door of iln sc cavities should i)re- sent four distinct ])lanes, and, foi- convenience, may be desig- nated as: the mesial plane; the distal jjlane; the lingual or palatal plane; and the buccal plane. The highest point of the flof)r of the cavity may be called the apex; and these planes will coi-i'es])oiid, ()]■ should, as neai'ly as possible, corres])ond, in })itch or angles to the })lane presenting as a bevel n])on surface of the cavity, to-wit: mesio-occlusal; disto-occliisal ; bucco-occlusal ; linguo-occlusah Thus if tlic cxfcnl of Ihc ai-ca of the iiih-iy in ('A\i'r\ niiicAKA'i'iox 7f) ri-i('ii()ii;il I'ch'ilioii with llic (';i\ii>' of llic tooth he (•ai'(^fully cx- amiiKMl, it w III he round to cxcccil the ai'ca of the inlay in stress I'clation with the ()i)])()sin^- teeth and sun-oundiii*;' tissues. In molar teeth and hieusjiids, which ai'e unusually small, and in which restoi'ations of this chai'acter are uecessary, the preparation of tiiese ])lanes nia\' he so Aaried tliat only two instead ol' four planes are made, and in these cases, the hi<;'li- est ])art of tlie (looi- shall l)e a dia^'onal line fi'om the disto-])Uccal to inesio-lin<;ual, or the distodin^'ual to tlie mesio-huccal angle ol' tlie tooth, respectively; thei-e will he the ()ccluso-disto-lin<;ual i)lane, and the Occluso-mesio-buccal ]:)lane. With a view to greater i-esi stance to fracture of the tooth, and to displacement of the iulay, planes are hy far to he pre- ferred to suj^i^lemental pins, except when these pins can he ])laced into the pulj) cluuiilier, or canals, and even then, a multi- plicity of these supplemental ])ins would needlessly complicate the preparation, in that the holes to receive tliem would neces- sarily have to he parallel to all vertical walls of the cavity and to each other. In vital teeth these pins should he looked upon as a means of last resource, and, when used at all, they should he as stout as the hulk of the tooth structures in that locality will allow; they should enter the tooth structure to a depth equal to at least half of tln^ir circumference and no gi'eater than their circum- ference. For molar teeth a 15- or Kvgauge iridio-platinum wire is used and for bicuspids a 17- or 18- or even 20-gauge wire will suflfice. There should he at least 15 per cent iridium in the platinum, and it may be threaded in two or three inch lengths and cut into small pieces equal in length to the circumference of the wire. These pieces are coated to half their length with graphite or whiting, and a small piece of pure gold is wrapped around the other half and joined to it with the Idowpipe. This pre- caution will insure the picking of these wires when the inlay is cast, and will also insure a perfect union between the gold of the inlay and these wires. 80 CASI' COLD AXI) I'OltCKI.AlX IXJ.AVS FijT. 13. 1^^ □ Fiti. 14. Fi2:- 15. E] vi-r ]<; Fiii-. i; CAVITY im;ki'ai;ati()X 81 Five Views of ax Upper First Bicuspid Fresextixg a Simple Occlvsal ('a\ity, axd tjie Cast Gold Ixlav Made foi: It. Fiws of the gold inlay. Figs. 30, 31, and 32. — .Showing the linisheil o[ieration, and liow the mesial portion of the gold inlay may lie replaced 'with porcelain. Stress Index: Upward, out am! backward and in and for- ward or Ixtraalveolar, lahio-distalli) and Unffuo-mesiaUij. 86 CAST COLD AND PORCELAIX JXLAVS Fiff. 33. Fiff. 34. Fiff. 35. Fig. 3G. Fiff. 37. CAVITY niEPATlATION 87 Five Views of a Lower Second Bicuspid Presexting a Mesio-Disto-Occlusal Cavity, and the Inlay Made for It. Fig. 33. — A view of the cavity. Note its well-defined step, the beveled gingival seat, the beveled enamel margins. Note the whole operation carried into areas of comparative immunity. Note the incline of the occlusal siirface of the cavity so that it forms an acute angle with the distal wall. Figs. 34 and 35. — Occlusal and mesial views of the cavity. Figs. 36 and 37. — Views of the inh\y. Note in Fig. 36 the definition of every part of the inlay, and in Fig. 37, the occlusal restoration anatomically conect. Note the lingual cusps and the well-defined marginal ridges. Stress Index: Down and inward, down and liackward, down and forward, or Intralixgually, intradistdlly and intramesially. 8S CAS'r OOl.l) AXD P()i;('l'",l,AIX IXI.AYS Fi-. MS. F'ux. MS). Fio-. 4(1. □ □ Fi-r. 41. Fip-. 42. Fie. 43. UU I'ii;. 44. Fig. 40. Fie. 4ii c.wi'iN n:i:i'Ai;.\'i'i()X S9 Nine Views of a Me.sio-Occlu.SxVf, Cavity i\ a First Lowku Bicuspid, and Eestoration Made for It. A Cast Gold Jxlav, the MESio-LixfiUAL Part of It. ix TrKX, IXLAVEL) AVITII .SVXTIIF.TIC PORCELAIN. Fi^s. ;J8, :!9, and 40.— Views of tlio c-avitv. Note the licvcl- iiiy of tlie walls, iiuirgins, scat, etc. Note the acute anylc foniieil by the occlusal and mesial surfaces of the cavity. Fig. 41. — A niesio-occlusal view of inlay. Fig. 42. — A cavo-surfacc^ view of inlay. Figs. 43 and 44. — Occlusal views of finished operation. Note how the margins of the inlay are carried to the ascending portions of cusp and sulci of the tooth. Figs. 45 and 46. — Mesiodingual and mesiodjuccal views of the finished operation carried into areas of comparative immunity. Note in Fig. 46 the outline of the porcelain insert. Stre:--s Index: Down and inward, down and backward, down and f(M\v;ird, or Ixtkalixclally, int I'odi.sialhj and i iiIvidik .sialli/. 90 CAST GOLD AXD PORt'ELAIX INLAYS Fig. 47. Fig. 48. Fiff. 49. ^^ Fig. 50. Fig. 51. Fig. oii. Fie. So. Fig. 54. ^AVIT^■ rr.KPAiiATiDX 1)1 Eight Views of a Lower Second Bicuspid Presenting a MESio-DiSTo-OccLrsAL Cavity, and the Eestoration Made for It. A Cast Gold Inlay, the Mesio-Buccal and Disto-Buccal Parts of It, in Turn, Inlayed with Synthetic Porcelain. Figs. 47, 48, and 49. — Viows of Cavity sliowing bevels, seats, and tapei', also occluso-disto-linyual ])lar.e and occluso-mesio-buc- cal plane. Fig. 50. — Occlusal view of inlay. Fig. 51. — Cavo-surface view of inlay. Note reproduction of jdanes. Fig. 52. — Occlusal view of inlay in position. Note the caiiy- ing of the margins of the inlay to the ascending portions of the cusps and sulci. Note reproduction of marginal ridges. Figs 53 and 54. — A'iews of inlay with synthetic insert in position on the tooth. Note the carrying of the restoration into areas of comparative immunity. Stress Index: Down and inward, down and liackward, down and forward or Intralingually, intradistaUy and intramcsially. 92 CAST COLD AX 1 1 I'OIU ICl.AI X 1X1>A^■S Fig. 55. Fie-. 56. Fig. 57. Fiff. 58. Fig. 59. Fi-. CI). c.wri'N im:i;i'.\i;ati().\' d;; A First Lower Molar Prksextixg a Labio- or Bucco-Oc- CLUSAL Cavity, and the Cast Gold Jxi.av Made for It. Fig .j5. — A'iew of the prepared cavity. Xote lievel upon nc- eliLsal surface carried to the ascending- portions of all cusps. Xote acute anglo formed by the floor and buccal wall of the cavity. Fig. 56. — A clearer view of tlie buccal surface and the taper and bevel. Fig. 57. — A view of the carved inlay. Fig. 58. — A cavo-surface view of the inlay. Figs. 59 and 60. — View of the finished operation. Stress Index: Downward, down ar.d outward, down in and forward, down, back and inward, ilown. fore and outwaid or Ixtraalveolar, introbucco-dislaJIfi. iiifraii ntimi 'msiallii. intra- distodingually and intraniosio-buccally. 9-1: CAST (iOLD AND PORCELAIN I^^LAYS Fio-. 01. Fig. 62. Fig. 63. Fio-. r,4. Fi2-. 65. Fijj. 0(5. Fiff. 67. Fig. 68. CAVITY pr.i;!'Ai;ATi()X 95 A Lower Molar Presenting a Disto-Occlusal Cavity, the Lower Half of the Buccal Wall Being Involved to the Full Mesio-Distal Extent. Figs. 61, 62, and 6.3. — Views of the cavity. Figs. 64 and 65. — Views of the disto-ocelusal inlay made for the cavity. Figs. 66, 67, and 68. — Showing the finished operation, the buccal surface having been restored with a porcelain insert. The disto-occlusal restoration was first made and cemented, til us leaving a simple cavity on the buccal surface. Stress Index: Downward, down and outward, down in and forward, down, back and inward, down, fore and outward or In- tra alveolar, in1 rahncco-distnlhi , intralinguo-mcsially , intradisto- lingualiv and intramesio-buccallv. J)(i CAST (lOlJ) AXI> roiU'Kl.AlX l^•lA^■s nan Fi-. 09. Fio-. 70. Fio-. 71. Fii □ Fio-. 74. Fio-. 7: Fiir. 71; Ki-. 77. Fio-. 78. CAVITY PREPATIATIOX 97 A DiSTO-OCCLUSAL CaVITY IN AX UPPER MOLAI{ AXl) A DlSTO- BuccAL Cavity in the SAjrE Tooth. Two Cast Gold Inlays for the Eespective Cavities and Three Views ok the Finished Operations. Fig. 69. — A view of the disto-lniccal cavity. Xote the bevel of tlie external third of the walls aiul the cunformity of the fioor to the wall of tlio tooth upon which the cavity presents. Figs. 70 and 71. — Vi;'\vs of the disto-oeclusai cavity. Xote the acute angle formed liy the distal and occlusal surfaces. X^ote the bevels and gingival seat, also the taper of the cavity. Figs. T'l and 73. — Occlusal and cavo-surface \ie\vs of the finished inlay for the disto-occlusal jxirtion of the tooth. Figs. 74 and 7-3. — Buccal and cavo-sujface views of the disto- buccal inlay. Figs. 76, 77, and 78. — Views of the finisiied operations. Xote areas of immunity into which the operations have b?en carried. Stress Index : Upward, out and backward, back and inward, fore and outward or Intraalveolar Bucco-Distally (listo-paUi- IdUjl and nusin-hiiccdJJi/ or in a latero-rotarv direction. 5)8 C'AS'I' col. I) AXn I'OIU'I'.I.AIX INLAWS Fio. 7ii. Fia-. SO. Fio-. 81. Fi-. n2. Fig. s;]. SO Fi'r. SI. Fi- S.J Fig. Si;. <^\vr^^• I'ltKi'AitATiox <)!) A Mesio-Djsto-Occlusal ('avitv ix ax Ti-pek ^Molai;, also A Buccal Cavity ix the SAJri; Tooth. Fig. 79— Viow of tlic 1. ureal cavity. Note licvd and con- formity of surface. Fi.l;-. !S(). — \'ic\v of occlusa! surface of cavity, also slunviiig mesial and distal ]iarts of it. Fig. 81. — Distal poition of cavity showing also the occlusal planes. Note bevels of all surfaces and taper of cavity as whole. Figs. 8:2 and «;!. — Occlusal and cavo-surface views of finished inlay. Xotc definition of occlusal carving in Fig. 82, ami defini- tion of cavo-surface in Fig. 8.3. Fig. 84. — Finishrd operation upon l)uccal suiface. Fig. 85. — Occlusal view of finished operation of mesio-disto- occlu.sal inlay. Fig. 8(5. — View of distal surface of completed operation. Xotc areas of immunity into which the whole operation lias lieen car- ried. Stress Index: Upward, out and liaciiwaid, hack and inward, fore and outward or Ixtkaalveolak Bucco-Dihtally (lislo-ixihi- iallil ajul mesio-haccalJ y or in a latero-rotarv diiection. 100 CAST GOLD AXD PORCELAIN IXLAYS Fig. 87. Fig. SS. CAV1T^" IMtKPAltATlOX 101 Figs. 87 and 88. — Two illustrations of teeth worn down l)y attrition, restored by nipans of the cast gold inlay, imitating the conditions of adjacent teeth. (Dr. E. Ottolengui.) Note the well-defined carving upon the occlusal surfaces and acquaint yourself with the fact that definition does not necessa- lily mean deptli. 101' CAST (iOI.D AND rolH'KI .A I X INI.AN' y 1 Fig. S9. Fia-. 90. Fig. 91. Fig. 92. Fi'r eri|jlieral Level is ofliial to one-half the depth of the eavity at its deepest part. Xote the four distinct ]ilar,eH, to wit: 'i'he mesial i)la]ic, the distal Jilane, tlie lini;ual plane, and the liu.-ral ]ihine. Xote also the apex. Fig. 90. — A liiK-eal \ iew of the cavity showing the apex of the four planes to be somewhat below the surface of tli:' cavo- peripheral bevel. Fig. 91. — Occlusal view <<\' the carved inlay. Fig. 92. — Cavo-surface view of the inlay. Xote the amount of frictional contact between inlay and tooth gained by this four-planed preparation of the floor of the cavity. Figs. 9.'! and 94. — ^■ie\vs of the iinished operation, a power- ful and lasting restoration. Stress Index: Downward, down and outward, down in and forward, down back and inward, down fore and outward or I.VTRAALVEOLAR, iniriihucco-disifiJhi . ill! niliiun'o-iiK ■-:i(iUii. intra- (lis-to-liiif/KaJlji, (111(1 infraiiu .sid-biiccdlhi. 104 CAST COLD AND rORCEr.AlX IXLAVS Fio-. 95. Fia-. 9G. FiR-. 97. Fig. 98. Fig. 99. Fig. 100. i'i-. Kil. Fio-. 11)1 t'AVlTV PREPAKAIIOX Kj.j A Complex Cavitv ix ax Uppkk Molar Ixvolvlvo Every Surface of the Tootil A Cast Gold Inlay Made to Kestoke the Tooth to Use AND AXATOJriC ACCEPTABLEXESS. Fig. 95. — A view of the occlusal proparation of the cavity. Note the occluso-disto-lingual plane and the occluso-mesio-buccal plane. Fig. 9(5. — A general view of the cavity. Note tlie well-sup- ported enamel, the beveled margins practically continuous, the well-defined steps, and the general tape;- of the whole cavity as shown in Figs. 96 and 97. Fig. 98. — A view of tlic occlusal surface of tlie carved inlay. Fig. 99. — A cavo-surface view of tlie carved inlay. Fig. 100. — An occlusal view of tlie inlay in position. Fig. 101. — A buccal view of tlie restoration showing how a synthetic insert may be made for this surface. Fig. 102. — A disto-palatal view of the finisiicd operation. Stress Index: Upward, out and l)ackward, back and inward, fore and outward or Intraalveolar, Bucco-Dlstally, disto-pal- ataUy and mcsio-hiiccally or in a latero-rotarv direction. lOG CAST coLn AM) I'oitriOLAix l^■|.A^■s Fio-. i(i;;. Fie-. 104. Fig. 105. Fig. 106. Fig. 107. Fio-. 108. Fitr. jo'j. Fi"-. 110. Fio-. ]]!. c'A\ l'r^ i'i;i;i'.\i;a rio.x 107 \i.\K \'ii;\\s OK A Skiom) I.owkk Molak Pke.senti.\(; a .MhsIO-DiSTO-OcCLISO lUCCAI. (JAVITY AXl) TwO iNTERIiOCKIXG Cast Gold Ixlavs ^Iadf, for It. Fij;. in.'i. — \'ic\v (if til.' (ici-luMil sihI'mcc incpiinMl t(i jiic-ciit tin' |il;iii;s fur aililnl f rirtioiial rclatinii ln'twccn inlay ami tintli. Xdtc licvi'ls jiicsciitiiiii' in all niaii;ins. V\ix. 1(14. — View of distal ]iart of (•a\ity. Xoto step, lir\cls, s at, and ta[ii'i-. Fii;. lO.j. — JUK'cal \ir\v. Xutc Ik'vl'Is of outci- tliird of cavity. Fig'. 10(i. — Occlusal ^•il■\v of nicsio-ilis-to-occlusto pnition of inlay. Note the lnckini; dcxicc in it liucco-occlusally. Fig'. 107. — Cavo-sui'fac;' \it'\v df tho Imccal |i correct reproduction of the occluso-disto lingual plane and the occluso-mesio-buccal plane. Figs. 125, 126, and 127. — Views of the finished operation. Fig. 125 shows how the mesial portion of the g'old inlay may, for cosmetic reasons, be replaced in the porcelain. Stress Index: Ujnvard, out and backward and in and for- ward or iNTKAALVKOr.AK, hiliio-d i.^foJI 1/ and Inunio-nx suiJIij. 112 CAST (JOIJ) AXD rOr.CELAIX IXLAYS □ Q Fig. 12S. Fie-. 129. Fig. 130. Fig. i:jl. Fio-. 1.32. Fig. y. Fi ('A\•|'^^■ im;kpai;a'I'I().v Eight Views of a Complex Cavity in an Upper Second Bicuspid, and the Eestoration Made tor It in the Shape of A Cast Gold Inlay. The Labial Portion of this Inlay has Bken, in TfRN, Inlayed with Synthetic Porcelain. Figs. 128, 129, and 130.— Views of the cavity and bevels of the various walls, margins, etc. Fig. 131. — Occlusal view of tlie inlay. Fig. 132. — Cavo-surface view of inlay. Figs. 133, 134, 135- — AMews of finished restoration showing lin;> of demarcation between gold and porcelain. Stress Index: Upward, out and backward, in and forward or Ixtkaalveolar, ](i})i()-dister1'('('t oih' in tliis u]i|i('i jaw. >lionld pi'oenl llie app<'ai-ance ol' an incline(l plane instead of a level liori/oiilal sni'face. This is |)ait icnlai'lx' essential and even imperalix'e when' tin- niiiniii/t of (hi/hi/c, support iini llic ciiiinirl is sijifill, and where 1lie ca\'ily is ol' a /Irplli f/i-calcr IIkiii llic I hirl.i/rss ol llicsc rcfhcdl ildlls. As a ;;nide, w Inch will, of c()nrse, lia\<' 1o he \aried as Ihe cases pi'esenl 1 heni.-el \'es, Ihe I'ollowin,!;' lahh' of the dirfei'ent ('A\■|'|•^ iM;i;i'Ai;.\'ri()N 1 1.) directions in w liicii slicss is hroiii^lit to hcai' iij)oii the dilTcrciit tcct li is here ,^i\('ii : The niiti rior tcctli in llic nppcr j;i\\ ni'c (•;ill»'(l npon to re- sist stress exei-cised ;i,i;;unst tlieni in an int i'aal\'e()hn', labial, and distal direction; that is, tliey are c()!istaiit ly I'oi-ced upwai'd, ontward, and hackw aid. The uppei- ciis|)ids. in a slight !>■ int raalxcohii', inarkcflly Fifj. 1.T7. — Stress index for lower teetli. Xote in tlie center of the qiiad- ranf^les representing- the molar, the heavy Mack marks, denoting intense intraalveolar stress, which is lessened as the anterior teeth are approached. Right lower second molar marked with thn letter P, indicating' this tooth as the most nearly perfect on this lower iaw. hd)ial, and e-. AVlieii tlie iielatin lias set. the riii.i;- Is inverted, and so, of course, is the model. With a sharp knife some of tlie ,i;-elatin is trimmed away, and lieeause of the elasticity of tlie ii'elatin, the mochd may he removed. Thus a -Aelatin im])ressiou of the model i.s secured, and into this impression, plaster of Paris may be poured and a record model obtained. In the stud\' of these models for determination of stress, the operator should be in possession of a comi)lete history of the patient. A careful examination of the nniscular structures of the face should be made and tli(» extent of the freedom in a laterorotai->' dii-ection enjoyed by the mandible, should he noted. It must be borne in mind that the shock to a tooth under stress mastication is inversely pi'oportional to the elasticity of the susi)ension li,i;ament, oi- the ])eri(lental membrane, and the free moljility of the mandihle. The elasticit.N- of the suspension ligament is inversely x^ro- ])ortiona1 to the IVee mobility of the mandible. This is a sec- ondai-y (-(Uidition ol'ten I'esnitin.i;- from a ])oor condition of the teeth, finally aifecting them to such an extent that the effort to masticate is ])ainful, ajid so the ])ati(-iit i-efrains from exer- cisiiif;- the necessai-y ])i-essure and shil'ls the mandible beloi-e the maxinmm of pressure oi- tension i'e(piii-e(l for maslicatifui has been exerted. This will, in tim<', jii-oduce the coiulition of a too fi'cely mo\ablc mandible; aniciisj)i(ls (d) Mdlars. L'. \\'li:it is iiicuiit by the iiiiiiiuiii' jirca oT a tn.itii .' ;i. Wliy arc ccitain airns siisc('|itiiili' tn ijci-ay .' I. Xanic till' iiiiiiiiiiii' ai'a^. •"). Xaiiic till' siisi-c|itili!i' areas. (). Wliat raclms (liter into cavity pri'icirat ion .' 7. Wli.-it are tlic rc(|iiiiiMncnts fi^r tin' foi niatimi of a cavity to receive a cast ;;-oliI inlay .' S. What instiuinents aic necessary for ]iro|ier cavity [ireparutinn ? !t. Name the j;;'iieral rules for ti'cth cutting. 10. What steps are taken hefure the cavity |irep;iratiim is cinnnieiiced ? 11. Name the types of cavities and their suhdivisions. 12. Explain what is meant by tlu' surgical mork iu the preparation of cavities.' Tlie formative work? The alterative work? 1."!. Why is the anatomic restoration of the occlusal surface necessary? 14. How are the mari;iiis of the cavity to l)e prejiared? 1.1. What general rule can be ai)|died to the foi'matixe pre^iaration of the cavity? l(i. Kxplain the teclniic of the preparation of tli" ca\ity flinir in teeth with deep cusps. 17. Illustrate in cidss srctimi the prepaiation iu molar or bicuspid of tiie follo\vini>- cavities: (a) Disto-ocidiisal, (li) Mesio-dcclusal, (c) Linguo-occlusal, (d) Bucco-occlusal. 18. Illustrate in cross sectimi tlie pieiiai ation in a m,'S surroiiiidiii^- it, aiit cut after the dei-ay ha^ Ix'iJi rejiiuv^ d in tlie preparation of a mesio-occlu!: \-cleil outwaiil. An inlay made for a cavity siudi as this nuisr ncvci- be put into position before thoriuighly lubricathig it with a small amount of carliolatc(l \ asciinc. llM CAST COLD AND POllCELAlX IX LAVS Fig. 144. — The wax inlay made iior the niesio-occluPo-distal cavity. It is mounted ui^oii a sj^rue wire and held in the cnieible former. Note reproduction of all linos and bevels in the wax. Fig. 14.';.— The finished inlay in position ujnm the toofli. The sniiiM iniHiunt of contraction of the {^old served heri' to more (dusdy I'urcc I he iim's:;iI ;iimI (list;il onlays against the tooth sui-fa'-cs. This is a liyhiid. not ;in iiihiy, Iml ;iii on inhiy. .M KSIO-niSTO-OCCU'SAr. CAST OOIJ) IXLA\' ^ '27) 15. I*i-()\i(l(' buccal or lahial and lingual .guides, and ])i'()- \u\v the ,i;'iii,i;ival seal in llic cavity by means of vci-y lliin cyliii- di'ical carborundum stones held in the coidi'aani^le handj)ieee and run uikU'i- water. 4. Polish all cavity walls by means of, first, coarse sand- paper, followed by liner sandiDajier, and ultimately by fine cuttletisli discs. The removal of all decay and all doubtful tooth tissue is imperative and should be done before any attempt is made to prei)are the cavity at all. The practice of leaving this until the last for fear of creating undercuts is reiDrehensibly l)ad ])i'actice. The gi-iniling or cutting of tooth structure, except it be done with chisels before all the decay has l)een removed, is likely to contaminate the as yet unaffected layer of dentine, a result as undesirable as it is ultimately disastrous. If the saliva interferes with clean rapid work, the rul)l)er dam must be ai)i)lied. All that has previously been said in the chapter on Cavity Prei^aration for simple, compound, and complex cavities ap- plies in M.O.D. cavities; that is, the adjoining teeth must be scaled and i)()lished, and by far the best way is to subject the patient's mouth to a thorough jorophylactic treatment. The dam may then be applied and the cavity joreparation undertaken and completed as directed. The tooth should then be washed with warm water, until no sign of debris exists; tooth and cavity are now flooded with alcohol (95%) and dried with a gentle w^arm air l)last. A gen- erous quantitiy of chloroform is now^ ajiplied and again the warm air is used to dehydrate tlie tooth presenting the cavity. The next api)lication consists of a saturated solution of potas- sium carbonate in glycerine Hooding every jiart of the cavity — this solution is allowed to remain in the cavity for about five minutes, when the warm air is again apjilied. The glycerine will further dehydrate the dentinal tubules, and the carbonate of potash, held in solution, will enter to efficiently occlude these with a material acceptable to the tooth economy. In order to exclude the ])ossil)ility of thermal shock, this ll'() CAST CdlJ' AXIi I'OltCKLAlX l^■|,A^■s ])roce(liirc' may l)c' rollowiMl up \\\{\\ a soliilioii of i-osiii in clilo- rofonn, 'o drain of rosin to -! di-ains of cldorofoi'in. This makes a very toii.uli \aniisli, wliicli will cliii.i;- to the (Iculiiie walls in tlie cavity, and wliicli will (Milcr tlic (Icntinal tubules to some extent. It is a nonconductor of tlicinia.l changes and Avill pre- vent sluK'k to the tooth wlien tlic inlay is set and after it has l)een set. Tliis varnish may ])e applied witli a ])ellet of cotton and it nnist 1)e dried witli the warm air. When all these preparations liave ])e( n ('om])leted, we may ])r()ceed to l)and the tooth or put a matrix on it and to force the wax into the (^n'ity — that is, Ave may ])i-oceed to make tlie wax inhiy. T]\h slioidd l)e (hjne hy the direct metliod as already de- scribed, or hy the use of the indirect as an accessory to the di- rect as also descril)ed. TJie mode of cavity ])reparation advocated and illustrated lie]-e for mesio-occluso-distal and B.O.L. inlays takes into con- sideration and ])artnerslii]) the sniall amount of contraction that will take i^lace in the castin^;' of the metal and make use of this property of the metal, in that thus a hetter coaptation is ob- tained between iiday and tooth. This preparation Avill not do for mesio-occlusal, disto- occlusal, bucco- or liii<;uo-occkisal cavities, because, in (i,ettinf!,- a closer adaptation mesially or distally, buccally or linoually, the g'old would be ])ulled away from the margins upon the occlusal surface, and tlie marg'ins u])on this surface would be u;il ciixitN? CIIAPTFJ? \'ll TlIK SKLb:("ri()X OF TWi: PL'OPKi; WAX Wax is a name ^iveii to various animal excietioiis or vo<;<'- tal)k' suhstanccs liavin<;- some similar and some identical ]jliys- ical 2^t'<^*i^diaiilies, l)iit dilferiiio- in eliemical composition, and possessin<;- a definite ])liysical iM(l!\i(luality. All waxes are liydrocarhon coni])onnds, icJattMl to the ;4rouj)S of oils and fats, common wax differing' from oi'dinarv wax in 2J0ssessing no glycerine. A great many waxes are known to commerce and employeil in tlie arts. The most widely known, or common wax, whicli forms tlie honeycoml) of tlie wonderful V)ees, is in its nntampered-witli condition, a comparatively hard substance, nnctuous to the touch, tasteless, and of a sweet odoi-. It is easily obtained from the combs by immersing them in hot water, when the wax will tloat to the sui-face as a thin oily fluid. This fluid is drawn oft" and allowed to solidify into cakes. This wax may l)e bleached or purified into cera alba or white wax, l)y the following 2)rocess : In tlie sliape of thin flakes, the wax is ex])osed to the air and light until the surfaces of the flakes have been bleached, much aftei- the process used in bleaching linen. The wax is then i-emelted, and tlius new surfaces are brought under the bleaching influence of light and air. This is continued until a uniform white wax is obtained. Bleaching ])owders as chemical ageids, are sometimes used, but they are objectionable because the whole of the chloride is not removed in the process, and in the subsequent ])urning of the wax, irritating and harmful fumes of hydrocldoric acid are given oft'. AVhite wax made ],\u-(' by the ])rocess of boiling and bleach- ing consists of: 127 128 CAST COLD AND POIU'EI.AIX INLAYS Creatine, 80 per cent, soluble Jii l)oiliii^' alcohol and an in- soluble ^vaxY substance called niyi'icin, nearly 20 i)er cent. A small ijroportion of cerolin gives hardness to the nuiss. The wax is tasteless, inodorous and seniitransparent. At 85° F. it becomes somewhat jjlastic, and may be molded with the fingers. It melts at 1-15" F. It is chiefly used for making candles, artificial flowers, and wax fruits. It has emollient proi^erties and is employed in the making of ointments. Because of its high jDrice, it is often adulterated with sj^ermaceti (an inferior wax chalk), starch and finely jjowdered silex, etc. Another wax is made from candleberry, known as wax myrtle, wax or tallow tree, or bayberry (Myrica Cerifera), a small tree, or more generally a low spreading shrub, a native of the United States, most abundant and luxuriant in the South. The evergreen leaves are dotted with resin glands, and are fragrant Avhen bruised. The drupes, popularly called berries, are about the size of peppercorns, and, Avlien ripe, are covered Avitli a greenish white wax. The wax is collected by boiling and skinnning them, and is afterwards melted and refined. A bushel of berries will yield four or five pounds. An excellent scented soap is made from it. Paraffine Avas practically uidvnown to the candle maker un- til 1847-50, when the late Dr. James Young discovered the method of producing hydrocarbons by the distillation of coal at a low red heat. It is now produced in Scotland from shale in large quantities; in the United States, from petroleum; in Germany (in smaller quantities), from brown coal; and in Burma, in yet smaller quantities, from rangoon petroleum. Crude i)araffine (technically "scale") contains, in addition to the hai'der ])ai-affine suitalilc foi' candh-s, soft ])araffine (used by match makers), and a small j)ro])oitioii of oil. The scale is melted and cast into thin cakes, which are then placed on slop- ing shelves in an oven kept at a regular temperature sufficiently liigh to melt tlie soft paraffine. The soft ])araffine and oil flow away, and leave Ixhiud a mass of hard ])ai-arfiii(' it'ady I'oi' the caudle maker. Miii('|-al wax is a name <'Ui|»l«)\('d foi- cci-taiu fossil lixdi'o- carboiis, occuri'iiix (iiicllx' in sinall (|nan1i1i('s in carboniferous formaliou. Tin- connnoncst owe of llicsc is ():nj,-ciil c, used in SKI.HCTIOX OK TIIK I'lIol'Ki: WAX 129 the caiidlc iiidust I'V. A j)i('])ai';it ion of this siiWstaiicc known as ozokcrii/c, is cinploNcd in \\i" niakiiiL!,' of ointniciits. It has tlic advaiita^'e o\('i- lard I'oi" this ))Ui-])os(' as it do( s not sjjoil with time and aftv, and (hx's not turn i-ancid. Tht'i'e is a f^roat vai-ictx" ol' tlicso vc^ctahh' and mineral wa\(^s, hid these < iiunierate(l will suffice to enable the reader to learn something' ol' tlie ori<4in and ])ioi)ei-ties of the most w i(k'ly known to the arts and eonnnerce. ]t must he said that in and hy themselves none of these waxes arc suitahle foi' inlay purposes, Ix'cause for this pur})Ose, the wax must ])ossess the following i)roperties : 1. It must leave absolutely no residue witliin the molerature between the surface on one sid?- or the other. Sometimes it will flash 50 or 60 times in a minute; sometimes slower. The reason is, it is a very sensitive test of the voltage that is passing through the wire. You hava often noticed that when the lights would go up high it would make your room light enough. When the current is at a high voltage the lamp is heated more, and that works the thermostat quicker and as soon as it is worked quicker it immediately drops down. The dancing you see is worked hy that voltage. "The wax is placed on this glass disc and the even tem- perature throughout the whole mass has a great deal more to ill) with the correct molding of wax in a tooth cavity than you tliiiik. It is peculiar, but a soft, wobbly condition of the surface of wax will invariably make it shrink from the cavity walls; whereas, if you have a wax of uniform texture, it will move to its place in an exact way, and there will be no change in form M-hen it cools off." (Taggart — Itmis of Interest, June, 1911.) 134 CAST COLD AND POUCKLAIX INLAYS of cold water is dirocted uinm it and the force \vliicli compelled it to assume its new shajje is removetl. An explorer may now be inserted into the body of the wax iuhiy and it inay be Avithdrawn to be carefully examined. [[' tile wax was in tlie ])roper plastic condition, and all directions liave l)een cai-efully followed, the wax inlay, if the cavity be simple, will be a perfect impression of the cavity, and it may be replaced in tlie tooth to assume its final shape, wdiich will he a i^erfect wax complement to the macroscopic anatomy of Fig. 147. — A glass of water at a temperature of 140° F. A largie cork carry- ing two banker's pins upon which two pieces of inlay wax are impaled. A pin to serve as a hanrlle inseited into the upper surface of the cork. The two pieces of wax arc constaiitly submerged in the water. The cork seals the glass and ket'ps the temperature more or less foii>t;uit fni an :iji]ircciiililc b iigtli ol" time. the tooth, and which shape is ci-catcd with caiwers and hui'- nishers ol' the dirfcrcnt i)att('i'ns illustrated. A\itli a jjeJlet of cotton dipjxMl into oil of cajeput or alco- hol, and de])j-ive(| of most of its oil or contents l)y rolling- the jx'lh-t in a towel oi- najjlvin, the wax inlay is liindly ])olislied, DIKKCT .MKTIIOl) OK CAKVlXd WAX IXLAV 135 care bcin^' cxci-ciscd to al\va\s ])()lisli towards ilic iiiar^'Iiis of the cavity. A^'aiii lliu e\j)loi'('i- is inserted into the l)ody of the wax, midway Itetweeii all margins, and tlie wax iiday is removed from the mouth, to he transferred to a ^lass of cohl water until it can he suri'ouiKhMl witli and imhe(hied in tlie refractory com- |)oun(l. In a vei-y (hdicate wax inhiy, it is wisei' to use com- pressed air to I'emove it from its seat in the cavity; this can readily he done hy aj)|»lyin;i' the hlast of ail- at the cervical ])art of the inlay. In com])()un(l ca^■ities the technic ol' ])re])ai-in^' the wax for the making' of the wax inlay, is, of course, the same, except that the tooth is Ijanded in extremely lar<;e restorations, wlien it ])econies necessary to join two or more of the cones of wax in order to ol)tain a piece large enougli for the inlay, and some surplus against which to ap])ly the force. AVhen this hecomes necessary, two cones of tlie softened wax ai-e hrought together at their hase, and a hot spatula is drawn longitudinally through hoth cones at four or five places on the cii'cumference, and twice through the joints of the cones horizontally. This will result in an iiiseparahle piece of inlay wax twice the nsual size. If the ])iece has stiffened too nuich in the process of han- dling, it is again impaled upon the pin and placed in the hot water to ])ecome properly i^lastic. The large piece of wax is now removed from the water hath and forced into the cavity, care heing taken to exercise the pressure in one direction, that of the floor of the cavity, and jjerj^endicularly to the walls of it and the hand which sur- rounds it. The wax will giadually cease to yield to the ijressure, and while the force is still in place, the wax must be cliilled with a stream of cold water. In this manner the handling of wax is hrought ahout under pressure, and thus the shrinkage and exjjansion of waxes, so much talked and written ahout, and Avorked up into red letter scareheads ))y investigators who shoot off at a tangent, really deserve no consideration at all if the technic laid down hy the oi'iginator of the ])rocess he followed to the letter. 13G CAST (!OLI) AXli roltC'ELAI X IXLAVS To r('i)( at a ])()iiit to Ix' carcriilly oLsc'iaimI: llic casu'sl way \o make a wax inlay foi- coinpoiiiKl oi- (•()iiij)lex cavities is to convert tliem into sini])]e cavities 1)y placin^;' a copper hand over and around tlieni. These hands may 1)e made uj) in (piantities out of sheet copper 36-gauge B6:S and kept on Inuid, or a matrix such as ilhistrated in Figs. 149 and 150 may he used. Tlie case presenting itself, a ])and of suital)le size is selected, triimned to gingival contour, and j^laced over the tooth after tlie cavity has heen prepared. The softened wax may then he forced into the cavity against the walls of the ])and, the pressure may then he removed and a stiff cone of wax may 1)e forced into the mass within the hand, the center of the mass having hi-st l)een softened with a suitahle hot instrument. It may he well to reiterate here that the wax is thoroughly plastic that is foix-ed into the cavity, the jiressure heing ex- ered in one direction, and that w Idle the force is still upon and hehind it, it is greater tlian the force acting upon the molecular structure of the wax in its attempt to shrink or alter its form; thus the deleterious i)art of tlie shrinking force or tendency will he overcome, and the result will he a wax filling, occupying every part of that cavity and ahutting all margins accurately. It again hecomes a c[uestion of two forces acting in opposite directions u])on a nioval)le hody (the wax), and it nuist he clearly seen that the greater force, if ])roperly applied, Avill prevent any change of form in the wax, in the wrong direction after it has induced it (the wax) to assume a certain definite shape; to-wit, that of tlie cavity. At tliis time the vai'ious margins occupy, or should occupy, the oj)erator's entire attention. Willi llic pi-o])er carvers, all margimd surplus of wax is icnioNc*!. With light and left hur- nishcrs and al\\a\s in direclion of the xarious margins that ])art of the wo]"k is completccl licroic we proceed with the carving of tlie occlusal suiTacc in oiih'i' to restore occlusal halance. A lai"ge hall f)r egg-sliapc(| huinisher is heated in Ilic gas or ah'ohol Ihinic, or i1 nia\' he aUachcd lo the swilchhoard, and the occlusal sui-facc of the wax iiilax', reeling in the cavity, is softened sufficiently lo enahlc llic paticnl lo occlude and Iritu- DIIJKCT MKTIIOI) Ol' ('Ai;VIX(i WAX IXI.AV r.v> Fig-. 148. — A spatula, a set of right and left and straight flat burnisher! right and loft carvers, and hand drills used by the author. lancets, 138 CAST CiOLD AND PORCELAIN IXLAYS rate; it' the Avax l)e lackiii<;' in l)ulk, a i)ortion may be added. J 11 tlie case of an inlay for a ]o^vel• tooth, we simply i)lace a ])ieee of inlay wax upon tlie occlusal surface of the wax inlay, and with tlie hot burnishers the two waxes are united. In an upper case, it is advisable to first soften the occlusal surface of the wax inlay in place, and then carry an additional piece of the wax into the softened surface. The union is coni- 2)]eted by again using tlie hot instrument and virtually melting the added jjortions into the wax inlay. AVhen the required bulk is obtained, and sufficiently sof- tened, the patient is allowed to occlude and to triturate, and again to simply occlude and hold that position while a stream of cold water fixes the wax. Xone but the occlusal surface will undergo any change, all margins will be found undisturbed, since the softening process was not carried to any marginal jJortion. AVlien the maxillary tension is removed and the mouth opened, the i^roj^er landmarks for occlusal carving will be clearly indicated and must be rigidly adhered to, if an occlusal surface that will be truly serviceable in the full sense of the word is to be obtained. SUMMARY FOR CHAPTER VIII Making and Carving of the Wax Inlay by the Use of the Direct Method 1. DcsciiljL' a iiu'thofl of bringing the wax to the proper ntate of plasticity l)y moist lieat. 2. Describe the method of making the wax pattern if tlie cavity is a simple one. '.I. Explain tlio details of preparing tlic pattern for conij)ouiid or cuin}ilex cavities. 4. Describe the finishing of the margins. ~). Describe tlio teclinic of carving the pattern to icstorc the occlusal surl'acc. CIIAP^rKK' IX TAKIX(i AX I.MPRESSIOX OF TIIK (\\V1TY AND MAKTX(i A J)TE FOll PROCM^yOlK'K in' TTIK IXDlirFAT METHOD 'riic |)i-()l)l('iii of making' a east ^old iiila\- l)y iiicaiis of" llie imjn'ession or indirect method, should really not be considered as a j)rol)lem l)y itself, l)ecause as such it at joresent admits of no solution worthy of the name. If used at all, it should prove hut an accessory step in the direct methoil, and so be employed in cavities so inaccessible, and under circumstances so remote that the infrequency of these stipulations shall in themselves exclude it from the routine of daily work. Some disto-occlusal cavities in the third molars may call for the indirect method as an aid to the direct, but under no circumstances should sufficient reliance be placed on an im- pression of sucli a cavity to complete the inlay uj^on a die made from this impression, without giving the wax its final shape in the cavity itself. The very name which the advocates of this method have given it, namely, the indirect method, in itself stamps it as something remote, far off; labor and time and energy are wasted in attempts to have an assistant assume that j^art of the constructive work in the laboratory which should be done right in the mouth. These advocates who claim satisfactory results from their ])rocedure, are being misled by burnished margins of their in- lays; they lose all frictional relation between their product and the cavity it is to occupy, but they honestly overlook the fault, grave though it be, l)ecaus(^ the method shifts res])onsibility to give time to work. The fact is, that if no better inlay could l)e made than the best Avliich have been made u]) to date by means of the indirect 139 140 (AST (lOLl) AXO POPvCELAIIs^ INLAYS iiietliod, llu' entire ])i-ot'ess of cast gold inlays would be a medi- ocre ])alliative measure, instead of the greatest boon to the dentistry-requiring jjublic, and if that had been the best it were ]Kissible to obtain, I doubt nuich if it would ever have been given to the profession at all. The first stej) in the construction of an inlay is to take a perfect impression of the properly prepared cavity. If the direct method is to be employed, that impression must be taken in the inlay wax. If the indirect method is to be emj^loyed, the initial impression is taken in a modeling compound, preferably "Detroit." The most j)ersistent argument of the advocates of the in- direct method is that they can not get a proper pattern of the cavity in using the direct method; in other words, they can not get a j^erfect impression of that cavity in inlay wax. If that be true, how does it liaj)pen that they can get what they consider a perfect impression in a compound, not nearly so relial)le in its physical i^roperties as is the Avax they should use. AVlien tlie direct method is emx)loyed, the margins of the cavity in the tooth are an ever present help to thorough Avork, and an ever jjresent deterrent to the slip-shod, just-as-good results. Once the margins are obtained, the major j)art of the carving may be done outside of the mouth, and the wax inlay replaced from time to time to insure correctness of manipu- lation. Proper occlusion may be obtained beyond the question of a doubt, and tliat, without the additional work of taking an additional ])ite in a filmy piece of wax, and without taking an imjnx'ssion of the affected tooth, can-ying the com])ound impres- sion of the cavity, and of the surrounding area for a guide to the desired correctness, and often that is as far as one can get to the con-cct r( suit, ergo the desire for it. The answer is made that while all of these stei)S are nec- essary, they may he done in llie laboratory, and here the great mass of errors, A\hicli Inllow liic nse of such materials as com- pounds, jjlaster, amalgams, variation in mass, temperature, and j)hysical strnctni-e in the hands oF a lahoratorx' assistant, who TAKIXC IM I'KKSSIOX AND MAKIX.) DIK 141 can only begin working upon and with these materials, after the errors have crejjt in, all combine to give a result not looked for, and this result is made to assume a semblance to tlie one Slide Fig. 1-19. — The upper figure shows a piece of sheet copper 33- or 36-gauge, cut as illustrated. The lower figure shows the same piece of copper formed into a band and locked by bending surplus back upon itself. Note at aa two vertical and two horizontal cuts to allow the improvised band to be forced apart in order to ob- tain contact witli adjacent teeth. Fig. 1.50. — niustiating a handy matrix in position upon a molar. I / looked for by using the burnishers freely, and the good or fairly good margins deceive most of us. 1-12 CAST COLD AXD PORCELAIN IXLAYS They wlio adiiiil tlicir incapal)ility to make an accurate impression of a ca\ity in inlay wax, luwe never familiarized themselves Avitli its i)liysical i)roperties, and should start right there. Let them study the wax, its physical properties under various temperatures, its adaptability, its toughness, etc. AVork it carefully, use it as if it Avere something alive, vibrant, re- sponsive; for it has in it all the things that give life and re- s])onsiveness, put there by a very inspiration. Then let these indirect method men comj^are their results of the time at hand and the time past. The advocates of the indirect method obtain an impression of the cavity for wliidi they expect to make an inlay, and they construct a die upon and into this impression. The result is a l^artial model of the tooth to be inlayed, the partial model being made of amalgam or cement, i^referably the former. Some proceed to form the wax inlay in this very die, which is ecpuvalent to making a complement to the human anatomy Avithout having that part Avhich is to receive the complement before you in its entirety. They guess at bulk, Avidth, length and contour, and if they guess correctly, tlie indirect metliod is a success and they proceed to giA^e it to those Avhom they designate as the rank and tile of their profession. XoAv, let me ask this of the rank and file and laymen: AVhat Avould Ave be likely to think of a man Avho tried to supjDly a part of one finger of a hand Avithout having the Avhole of that hand before him all through the operation? AVould Ave consider him correct? Of course not, l)ecause he Avill liave consti'ucted the complemental portion Avithout due reference to tlie wliole; Avithout having at his disposal a comprehensive vicAv of that with Avliich the complemental part must ever interplay and hai-monize, and so the least these indirect method advocates can do is to have before them a complete model of the tooth. Some of them, realizing this, obtain a Avax bite (indefinite and inaccurate), and so to speak, plant this die into the Avax bit*', filling in tlic rest oF it willi plaslci-. Too often, almost always, a mici-osco])i(' shin Ink'cs place, nnd innl1inii('roscoi:)ic errors are the I'esult, Tliey are also ])roii(' to lunp upon llic suhjcci of gold and porcelain inlays, as if Die jx'olilcms wo-c one, ignoring pnr- TAKIXC; JMPKE.SSIOX AXI) .MAI':iN(; DIE 148 J30sely or otlici-wisc, the fact that llici-c is no coiii])arisoii ]>('- tween the two, cxcci)! that both act as lilliii<^'s or inlays for a tooth. Tlic i)r(>i)ai'ati()ii of the ravit>- is wholly different; the phys- ical [)r()|)erties of the matei'ial aic wholly AIX J^s'LAV.S Only half of tlio nmnher of trays is required for the lower molars; for wliai" Avill serve as a disto-occlusal tray on the right side, may be used as a niesio-oeclusal on the left; and so hut two mesio-oeclusal and two disto-occlusal, and one mesio-disto-occlu- sal tray for the molars, will he necessary. "\Ve shall need one niesio-occlusal and one disto-occlusal tray for the second bicuspid and the same number for the first lower bicusijid right and left. Two sizes of hinged trays for each anterior lower tooth may be made. Right and left being inter- changeable, only six trays will be required for that region. AVlien it becomes necessary to obtain a reliable impression of a properly prej^ared cavity, the corresponding tray is se- lected and that joart of the tray which is contiguous or not hinged, is tilled with a small amount of modeling comj)osltion, softened in the Bunsen burner. Care is to be exercised not to burn the comj^ound. The two hinged and lubricated portions of the tra}^ are in- verted and used as a handle. The compound-carrying tray is now carefully brought over the tooth and centered; then with a direct pressure ujoward or downward, as the case may l)e, the cavity is filled, and that part of the tooth enveloped in the soft compound. Because of the unyielding tray, the impression material will be forced against the margins of the cavity, while the surplus will be expelled buccally and lingually. The two hinged wings of the tray j^reviously lubricated, are quickly closed upon the buccal and lingual sides respectively, and the surplus of the comi)ound is held against the tooth under pressure. A stream of cold water, directed Ti])on the tray, will chill the compound. The liiiigc*! wing upon ilic lingual or palatine surface is again in\('r1('(|, the sui'plus (•()iupoun(l is cut away with a sharp lance; llial ^ufface of the tooth is lubricated with some white vaseline; a small piece of softened im])i'ession material is placed ui)on the inner surface of the wing of the tray, and while the lattei- is firmly held in position, the Fornier is closed .MAKINC |)IK 147 A sticaiii of cold waliT will accclcraic \\\v liai-dciiiii^' of that surface, and llu' hinged win^' u])()ii tiic Iniccal surface is sub- jected to the same iiiauiijulalioii; lliat is, it is inverted, the sur- l)lus cut away, the toolli surface is luWricated, and a ])iece of sol'teiR'd inij)r('ssi()ii material is jjlaccd iij)()n tlic liin,i;(Ml sui-face, \vheu it is a^'ain rcinNcrted and forced to place. A^ain a stream of cold water accelerates hardening- of the compound. Wliatever sui-])lus of comjjound may sliow giu^ivally, may he femoved witli a sliaij) huice, and we are now I'eady to ol)tain an impression of the surrouudin*;- teeth, a model fi'om whicli im|)ression may ^ive us our cavity and its ri^ldful environment. It will he necessary to keep the saliva ejector in the pa- Fig. 158. FiiT. 159. Fig. 158. — Coniijletc impression of tooth and eavityomljcdilod in idaster im- pression of adjacent teeth, ready for the packing of amalgam die. Fig. 159. — ConiplotP impression of tootii and cavity, removed from the mouth. tient's mouth, in order to carry off the water used in chillin<;' the compound. A unilateral tray for the particular side of the mouth is selected. A mix of plaster of Paris, of the consistency of thick cream, is put into it, and the tray, plus i3laster, is quickly car- ried to the side of the nioutli and carefully foi'ced to i^lace. The plaster is given from five to ten minutes to set, and a spray of cold air is directed upon it while it is setting, when the cup is removed and the plaster impression carefully broken away from the tooth. The buccal or lal)ial ]wrtion is removed first, l)y placing the index finger of one hand under tlie ^^laster ]-i8 CAST tlOlJ) AND POIiCELAlN INLAYS buccally, and keeping the index linger of the oilier hand upon tlie niorsal surface of the impression. Tlie patient is then directed to open the mouth nuicli wider, the index finger under the buccal side of the impression is ro- tated towards the oral cavity, and usually no difficulty will be experienced in the removal of that joart of the impression. An upward and downward pressure upon the lingual i^art of the impression will readily dislodge that portion of it, and so all parts of the plaster may be gathered to be again re- assembled in the cup after they liave been allowed to become moderately dry. The compound carrying tray will be found in perfect cc- dition upon the tooth requiring the inlay. All evidence of plaster is now removed, and the outer or buccal hinged i^art of the tray is again inverted, as is the lingual or joalatine. Grasi^ing these two hinges, mesio-distalh% the rest of the imiDression will come out and may be brought into full view outside of the buccal cavity. Again the two hinges are jDut back into their respective positions, and Ave shall have an impression of the entire tooth, for which we are about to make a metallic complement. Because of its j)eculiar position within the i)laster impres- sion, the tray carrying the compound impression of the cavity will be immovabl}^ fixed. More plaster is added to the i)laster impression in order to strengthen its w^alls; all the plaster is varnished, and we are ready to pack the amalgam into the com- pound impression, so as to form a die, reproducing the tooth that requires an inlay. THE MAKING OF THE AMALGAM DIE Foi- tlie ])Ui-pos(' of iiiak'iiig a die, ( itlicr a silver or copper alloy niay be used. TIk; wiiter has been able to ol)tain much more clearly de- hned juargins and outlines with the copjoer alloy, and would, therefore, commend it for this purpose. It is also ]iiucli harder and not nearly so likely to become snbjeet to distorting iiKK'ciii'acy. TAKIN(i IMPKESSIOX AND INIAKIXf; DIH 149 A quantity oC llio alloy, vai\vin<;' directly as the size of tlie case, is placed in an iron s])()on and carefully heated over tlie Bunsen flame until the globules of mercury appear upon the surface of the small cojjjx'r amalgam l)i-i(piettes. The mercury-exu(rm<;' mass is now thrown into a AVed^wood mortar, and tliorou,c,hly macerated under pestle. This macera- tion is kept u}) until the mass seems and feels smooth; if the mix appears thick, more mercury nuist be added, so that a thin and readily flowing- nuiss may be obtained. The AVedgwood mortar is now upset upon a sheet of manilla paper, and with a stout, broad sj^atula of German silver, or a polished steel knife, the amalgam is spread over the largest possible area of the i^aper in a thin film, and consid- erable pressure is use^ Fig 160. — :N[o(lel presenting a view of amalgam replica of tooth requiring restora- tion in correct relation to adjacent teeth. rx Fig. 161. — Model lubricated wi/th mixture of castor oil aud glycerine. ex])elle(l and ilic ainalgniii Ix'coines (jiiilc hard and l)ut just worl\al)h'. AVith lai-ge, (hit padding iiisl ruiiiciils this mass is now grad- ually and wilh cotistantl)- increasing j)ressure and a rocking motion, put into and onio llic I'cst ol* the amalgam. The excess of nKTcury, il' an\- he presetil, is now i'eni()\'ed h>- hurnishing several la>(M-s of lin foil oNcr the Hal sui-face ol* 1lie iiijiss, and willi a Hal clilselcnd iiisl ninienl, an ii'regular TAKING Ii\rrnESSIOX AND IVrAKIN(; DIE 151 I'cccss t'((u;il ill (k'])lli to nhoiil oiic-lliii'd of its greatest (liaiiictcr, ,is sunk into tlic mass of anial^ain. The i)la.st("r iin])r(>ssi()n carryin^j,- the hinged tray and coni- |)oiind impression n\ hich contains the amalgam wliieli has ])een introduced, is now h-iid asich' for at least twelve hours to give the amalgam an ()i)i)()rtiinity to thoroughly crystallize. The next ste]) shouhl he the immersion of the amalgam- carrying inij)ressi()n into water, and the tilling in of the rest of the im))ressi()n with plaster of Paris, when, after three-quar- ters of an hour or one hour's time has elapsed, the imi)ression tray is freed from surrounding plastei', the plaster impi'ession is carefully hroken and cut away, exposing a ])laster cast carry- ing the hinged tray and com])Ound. The cast is now immersed Fig-. 162. — Occluded models of case requiring restoration. Note in the upper arch the amalgam die in correct relative position and correct occlusal relation to the lowci' model. in water at a temperature of 135° to 140° F. for about two uiinutes, Avheu the hinged portions of the tray may he easily inverted and all of the compound impression removed from amalgam tooth and cavity. We have no^v before us a plaster cast securely carryhig a complete copper amalgam reproduction of the tooth requiring a gold inlay, and if the directions prescril)ed above have been studiously followed, the cavity in which the wax inlay is to be formed may be used as a w^orking base \\\)on which the ])re- liminary carving may be done. A w^ax bite previously secured from the patient's mouth is now mounted upon the plaster cast that carries the amalgam 152 CAST GOLD AND PORCELAIN INLAYS tooth, and the opi)osiiig tectli are secured ])y filling the ^vax impression on the reverse side of the wax l)ite with a mix of plaster of Paris. Both nj^per and lower may now he mounted upon an adjustable crown articulator. AVhen the plaster has set, the articulator carrying the models and bites is immersed in hot water, and the wax bite is removed, disclosing the amalgam tooth in the correct relative occlusal position to the opposing teeth. All of these opposing teeth are now thoroughly varnished with a thin solution of sandarac, and this is allowed to harden. AVe are now ready to make our wax inlay for the cavity. A cone of inlay wax of suitable size is made ready for use by softening it in hot water in the manner described under the heading of making and carving the wax inlay by the direct method. The softened cone of wax is forced, as also previously de- scribed, into the lubricated cavity, in this instance, of the amal- gam die instead of the tooth. "While the wax is under the influence of the finger pressure, it is chilled and held in this position until it has hardened, then the pressure is removed. All we are concerned with at this stage of the operation are the margins and seat of the cavity, and the approximation of the wax to this seat and these margins. "With the proper carvers and flat Inirnisliers, right and left, all but the occlusal surface of the wax inlay is completed at this time. A stream of cold water will thoroughly harden the wax and a jet of cold air will dry it. A ball burnisher is now heated in the Bunsen flame and the unfinished occlusal surface is sof- tened ceiitially: that is, the hot insti'ument is allowed to enter the wax inlay ai)out half way down into the body of it, care being exercised not to a!h>w the heated instrument to work Ihroiigh the wax 011I0 ilic scat of ihc caxiix', or up to the mar- gins of it. The vai'iiished and raiutl}' luhricated opjj(xsi]ig teeth are now allowed to descend or ascend upon the wax in order to designate the landmaik's Coi- occlusal .'ai\iiig. A close stud\' of loolh ana1oni\' should he made bv ilie in- TAKING IMPIIKSSIOX AND MAKING DIE 153 lay workci', nn illi a view to correct reproduction of tooth sur- faces in ftonci-al and tlie occlusal surface in particular; the sulci and dee]) iissures, the extreme cusp, elevation, the ini- ])ortant niarf-inal i-id<;cs functionino- in their capacity as guard- ians of the interdental tissues, all these must he carefully rcpro', llian it would lo olilain 1lu' same i-csult willi llic dii-<'('1 method. TAK1X(; IMlMtKSSIOX AND .MAKIXi; DIE 157 SUMMAKY FOR CHAPTER IX Taking an Impression of the Cavity and Making a Die for Procedure by the Indirect Method 1- (iivc tlic reasons why in the writer's opinion tins metiifxl is unscientific. 2. When may it be used in conjunction with the direct method? 3. Describe the trays devised for use with the indirect nicthod and the tochnic of tlieir applicatifjn. The Making of the Amalgam Die 1. Why is a copjx'r alloy preferable? 2. Describe the method of x'''^'I):^i"i'ig the copper alloy for the packing of the compound. 3. Describe the method of making the wax pattern from the metal die. 4. Describe the technie of transferring the wax pattern from the die to the cavity and the conformation of the pattern to the tooth. 5. Describe the detail of inserting the sprue wire into the wax pattern and its disposal before investing. CHAPTER X THE INVESTMENT, OR REFRACTORY, COMPOUND As tlie lieadino- of tlie chapter implies, the investment is tlie mass into which the wax inlay is emhedded, to form a mohl into wliich, npon vohitilization of tlie Avax, the inetal may ho forced to assume a detinite shajDe. Because the metal must he forced into this mold in a lici- uefied condition, and hecause it requires a great deal of heat in order to liquefy the metals used for inlays, the compounds or suhstances that make uj) the investment must he refractory, that is, they must in themselves and in comhination with each other joossess the iDrojDerty of resisting disintegration under heat of considerahle degree. "While this is an important property of the compound, it is no more so than the projierties enumerated helow, and unless a compound can meet the requirements stated, it is unfit to he used for the making of molds into Avliich inlays are to he cast. Since these castings are to he made under pressure of one kind or another, the comj^ouiid used should he strong enough to resist such pressure; and since such pressure varies, the com- pound should possess a safety margin of pressure resistance at least doul)le that of the amount required. JJecause oi' accui'acy j-equired in the rein'oductiou of line lines, angles and margins, the compound must he one that Avill crystallize in sucli iniiiute crystal f'oi-inaliou as will enahle these crystals to moxc into every line and dejnx'ssion of the pattern. At the same time the crystals must be of such shajjc that Ihc hardened or set mass will present a structure sufficiently ])Oi'ons to caiwy off any gases foi'ined in the ]ii()l(l dnring ihc ])rocess of vohililizalion, and dnring 1iii' process of Ihc inlrcxhic- tion of the metal. Smoothness of 1iic mass nmsl also he (M)iisi(h're(l, and sinc(^ that is a (|nali1y lliat is nsnaily ohlnincd at the expense of ]5S J.WKSTMHX'I', OK JtKIKAC'I'OltV, ( 'O.M l*( )r X I) 159 j)()r()sity, it iji'csi'iitt'd at lirsl an almost iiisiii'iiiouiilaljlc ohslaclo ill tlie chain of steps essential to success in the art. Finally, the Avorkin^' (jnalities of the mass, M'hen mixed for use, must be such as to <;ive the user a sufficient amount of time to carefully invest his ])attern, wliicli means that when properly mixed, the mass x)reseiits the appearance of a cream, smooth and easy (lowin<;', and free from air cells. A ^reat many of the refractory agents su^'^ested themselves to the investigators, many of whom are even now engaged in the j)robleni of trying to compound a more perfect investment material. All of them have been compelled to retain as a portion of the mass, a considerable quantity of plaster of Paris as a bind- ing force for the wdiole. Plaster of Paris is manufactured from the mineral called gyj3sum, which is comparatively soft. Chemically, it is a hydrated sulphate of lime, CaSOi + 2H2O. Its specific gravity is 2.31 and its hardness is from 1.5-2 of the mineral scale. The three most frequent varieties of it are known as ala- baster, a marble-like mass usually faintly tinted and translu- cent; a selenate, which is crystallized and transparent; and a variety known as satin sj^ar, which has a pearly opalescence due i^erhaps to its fibrous foundation. Gypsum has a wide geologic distribution, the extensive beds of the common variety generally occurring as irregular concre- tions in nodular masses, and it is frequently found associated with rock salt. A mineral known as anhydrite or anhydrous sulphate of lime, found near the Harz Mountains and in i:)arts of Xova Scotia, may be converted into gypsum by the addition of water. (lypsum contains 21 per cent of water, which can l)e driven off by heat, it is burned in kilns at a temperature of 250° F., then ground to a fine powder, ainl as such, it is known as plaster of Paris. This recombines with water, evolves heat, and crys- tallizes at the expiration of a few minutes. If, in the burning of the gypsum, the temperature be raised to or about 480" F., and then ground into a fine powder, it will be found to have lost its power of dehydration and in this 160 CAST GOLD AND POliCELAlN INLAYS state, it will not set Avlien mixed with water and it is said to be dead burnt. At ordinary temperature, gypsum and jjb^ster of Paris are soluble in water, in the proportion of two and a fraction of the solids to 1000 parts of water, and its jDoint of maxinmm solu- bility is about 95° F. Plaster of Paris shrinks upon being heated, and in itself is therefore an unreliable mass for molds which are to receive high fusing metals, or allo^^s in a liquefied state. Some , of the other materials used as refractories are the compounds of silica, alumina, magnesia, and calcium. Of these the silica is the most important, for although utterly lacking in tensile strength, it has the property of ex- i:)anding when heated. * SILICON Silicon is one of the nonmetallic elements: symbol Si; atomic weight 28.3(0-16); sp. gr, of crystalline form, 2.49. It may be obtained in two different forms : viz., the amorphous and the crystalline. Amorphous silicon presents the apj^earance of a dull brown powder, prepared by heating silicon with aluminum. It is nonconductor of electricity, and when heated in air or oxygen, its external surface burns brilliantly, and is converted into silica, which fuses from the extreme heat and forms a coating- over the unburned silicon. Deville obtained crystallized silicon in regular six-sided pyramids of a dark steel-gray color. A somewhat impure form is prepared by the Carborundum Com- pany of Niagara Falls by heating coke and sand in an electric furnace. Silica, or silicon dioxide, exists both in the crystalline and in tlie amorijhous form. The best examples of the crystalline form are rock crystal, quartz, chalcedony, flint, sandstone and quartzose sand. Silicon in this form has a specific gravity of about 2.9, and is only attacked with difficulty by potash or hydrofluoric acid. The amorphous form exists naturally in opal, and is obtained arlificially as gelatinous silica, etc. It differs fi'oin Ihc foi-inoi- in its specific gravity, being about 2.2, and in ixvEST.MKX'i", oi; i;Kri;A("r()i;\', com rorxD 161 its bc'iii^' raj)i(lly dissolvt'd by jjotasli and l)V liydrolluoric acid. Pure sillcd (ds it occurs In rock crusted, for eXrample) is perfectly f rdiisjxnoti (Uid colorless, mid is sufjicicntly liard to scrcdcli f/ldss. The heal of the o.ii/li i/d rof/cn Idowpipc is re- quired for its fusion, ulicu il uiclls into a I runsparcuf f/lass, cupdhlc of hciufi (IrdU)i out i)do electric th redds. SiTH-ic acid may be precipitated by addition of hydi'ocldoric acid to a so- lution of sodium silicate. l>y exposing the silicic acid to red heat, pure amor])lious silica may be obtained. The solubility of hydrattnl silicic acid in water accounts for the presence of silicic acid in mineral springs, and in the geysers of Iceland, as well as for its gradual separation from those Avaters in the form of petrifactions. Silicates are salts of silicic acid (of which several hydrated forms have been obtained) or combina- tions of silicon dioxide and metallic basic oxides. They may be divided into five classes: (1) Orthosilicates, derived from HiSiOii (2) Metasilicates, from HoSiOs; (3) Disilicates, from HoSioOr, ; (4) Trisilicates, from HoSivO,. ; and (5) Basic silicates. They occur abundantly in nature, all the forms of clay, felspar, mica, hornblende , augite, serpentine, etc., being compounds of this description. Most of the silicates are fusible, the basic silicates fusing more rapidly than those of wliicli are either neu- tral or contain an excess of acid. Excepting the silicates of the alkalies, there are no silicates which are soluble in water. Silicon is largely employed in the manufacture of glass, chiiia and porcelain. The use of silica in giving firmness and rigidity to various parts of the animal organs is exemplified in its free occurrence in the quill part of the feather of birds, in the shields of certain infusoria, and in the spicula occurring in sponges, while its similar use in the vegetable kingdom is seen in its more or less abundant presence in the stalks of the grasses, more particularly in the cerecds and in the bamboo. Silicon combines with several other elements besides oxy- gen, the most important comjDonnds being silicofluoric acid (HaSiFi) and silicon carbide, or carborundum (SiC), Avhicli is very hard and used for grinding and polishing. Silicon fluoride (SiFi) is a colorless gas usu-ally prepared l)y heating together calcium fluoride and strong sulphuric acid. It is decomposed into water silicic acid, and silicoflnoric acid. IGll CAST (JOIJ) AND roilC'ELAlX INLAYS CALCIUM Calcium (synil)ol Ca; atomic w( i,i;lit -lO.OD) is the metal I^resent in chalk, and other compounds of lime. It may he obtained by passing a current of electricity through fused chlo- ride of calcium. It is a yellowish white metal, intermediate he- tiveen lead and (/old 'ni hardness. At ordinary temperatures, it rapidly decomposes in water, forming lime, CaC, ichile hy- drogen eseapes. It forms an oxide, lime, having the composi- tion of forty parts of calcium and sixteen parts of oxygen. Sulphate of calcium, CaSOi, is the chief constituent of gypsum. It is present in most drinking waters, rendering them perma- nently hard. Temporary hardness, due to the presence of car- bonate of calcium or chalk, is removable by boiling. MAGNESIUM Magnesium (symbol }ilg; atomic Aveight 24.32) is a metal which is very widely distributed over the globe. It is present in magnesite, magnesium carbonate, dolomite, carbonate of lime and magnesia, asbestos, silicate of lime and magnesia, meer- schaum-silicate of magnesia, kainite, and in other minerals. It exists in mineral waters and the sea as sulphate and chloride, the sulphate being known as epsom salts. The metal is made by fusing together the chlorides of potassium and magnesium and IJuor spar, and adding metallic sodium with great care. The crude metal is finally distilled and pressed in a semifluid state into ribl)on or wire. Magnesium has a silver white color, which is tarnished by moist air. It is a very light metal, its specific gravity being oiil>' 1.75. It is readily volatiU-, and, when lighted, burns in air with an intensely brilliant light, rich in chemical rays. On tills account it was, until superseded by the electric light, nmch used ill pliologi-a])li\', while in signaling and pyrotechny it plays an important jjart. When magnesium l)urns in aii-, it forms a white ash con- sisting of the oxide, nuignesia, ]\lg() (whicii may also be pre- pared by heating the carbonate). The caihonate, MgCO^, is found in nature, but for medical pui-poses it is prepared by JXVEST.MKXT, OI! r.KI'KAC "^()l;^■, COM I'OI'XI) !().') precipitating- a soluble iiia.uiK siiiiii salt with carhoiiate of soda. Although iiisolul)le in water, this substance readily dis- solves in water containing carl)onic acid, and this solution is known as fhiid magnesia. The sul|)hate, MgSO, • 7H.0, or ep- som salts (an infusion ot whicli with senna is known as l)lack draught), occurs in nature, and is well known as a domestic remedy. Citrate of magnesia is the popuhir name for a granu- lar, effervescing aperient. It consists of a mixture of bicar- l)onate of soda, tai'taric and citi-ic acids, sngai', and a small trace of e])som salts. ALUMINA Alumina is the most abundant of the earths; it is the oxide of metal aluminum, the formula l)eing AUO.. It occurs in na- ture abundantly in combination with silica, associated with other l)ases. The most familiar of its native compounds is felspar, a silicate of alumina and potash, K^O, ALO:^, GSiO.. Certain varieties of this, by exposure to the atmosphere, l)e- come completely distintegrated; passing from the state of hard, solid rock, such as we are accustomed to see in building granite, into soft crumbling earthy masses. Clay consists of a silica and alioniiia in a state of cJiemical comhiuation. It never is pure alumina, hut the cjuantitij of silica united to the latter is vari- able. Wlunt it is pure, claii is quite white, but more frequently clay is red, owiiu/ to the jjresence of oxide of iron; or black, from the diffusion throuyh it of vegetable matter. From alum, alumina is prepared by adding to a solution of the former, water of annnonia, as long as it occasions a pre- cipitate. AVlien alumina is precipitated from a solution con- taining coloring matter, such as logwood, etc., it carries down the color chemically united to the Hocculent jn'ecipitate; in this way are formed the colored earths called lakes. Alumina in the state of the precipitate, after l)eing gently dried, is readily soluble in acids and in alkalies; but if strongly heated at a cer- tain temj^erature, it j^resents an appearance of sudden incan- descence; it loses the associated water, contracts f/reatli/ in hulJx,, and now forms a white soft powder, not at all r/ritti/, and Avith difficulty soluble in all'alies and acids. Alumina, as gen- erally prei3ared, whether hydrated or anhydrous, is soluble in 1G4 CAST t;OLD AXl) POl'vCELAIX IXLAYS water, j)OSsesses no taste, and docs not alter eolorin,!;- niatters, l)ut it has also been obtained in an allot ropic liydrated form, Avliieli, in the presence of a very small x)roportion of acetic acid, is largely soluble in Avater, from which a minute trace of sul- furic acid j)recipitates it. In the anhydrous state it absorbs water with great readiness Avitliout combining with it, so that it adheres to the tongue, and if left parches it. Claij retains this property; the ends of tobacco pii:>es are often glazed to prevent adliesion to the lips or tongue. Alumina is not fusible by a forge or furnace heat, but it melts before the oxijhydrogen blowpipe into a clear globule, i:)0ssessing great hardness. The more coarsely crystallized specimens form the emery which is used for polishing; the transparent crystals when of a bhie color, owing to a trace of metallic oxide, constitute the precious gem, the sapphire; and when red, the ruljy. Alumina, in com- mon with other sesquioxides, is a feeble base. Like alumina, magnesium and calcium are unreliable as to constancy of bulk upon accession of heat, and so were, in and by themselves, not to be favored as constituents of any mass to be used for molds into wliich too high-fusing metals were to be cast. The apparent impossibility of obtaining all these refrac- tories in a pure state was another trying joroblem which had to be solved before a really worthy compound could be produced. It may be safely asserted that all the investment com- pounds at present offered to the profession, contain one or more of the refractories enumerated, in a varying combination with jjlaster of Paris; some are carefully determined coi-rect relative combinations; some are haphazaidlx' tliiown togetliei-, mixtures of ({uestionablc A'aluc, the sale of wliicli should he ])i-()- hibitcnl. So ]iiucli of the success in casting dej)ends upon a deix iid- al)le mold that only the very best at loresent to ))e o))taine(l should bi' fo]isidered. For a long time I used a compound which T mixed foi- my- self in accoi'dance with the following formula: Plaster of Paris "/> t Rilox ijIm Graphite flakc-s (small; vl'i— -)-iJ— 1- INVESTMENT, Oil ItKFIIAC TOlt V, COMPOUND 1(35 Tlic process of Jiialart of the furnace is a funnel of a three-inch diameter and about eight inches high; 173 17-t CAST COLD AND r()i;ci:CAlX IXCAVS tile cliauK'tcr oi' the runnel gradually (limiiislies nntil it registers two inches at its extreme height. Ujion the interlaced steel wire, resting n])on the fire brick of the lower half of this furnace, the metal flask containing the mold is jjlaced. Here the first step in guarding against too rapid heating must take place. The l)UiistMi burner sliouM l)e set to one-third of its capacity, Fig. 10(3. — Tag<;;irt autoinatic, (yas) l)iiriu'r for iciikis iiii; w iix paltcni I'l-nni mold. The gas is ma,' with the size of the llask, wlien the furnace is again opened and tlie flask looked at. Tt will ))e seen that tlie cruci))le Jias over it a coat of carbon. AVlien the drying jx'iiod has passed, the flask is placed directly in the ceider of the latticed steel wire frame; the Bun- sen flame will then l)e immediately beneath it. Tlie furnace is closed and the lUmsen bui-nei' is adjusted to its full capacity for one or two minutes. '^Phe In^drocarbons will burst into flame, after which time the flame under the furnace is extinguished and the furnace o])ened, to reveal a mold clear of carbon, or any other deposit, and of a grayish white color, speckled here and there with the iron-gray of the graphite. The flask is carefully grasped with the flask forceps, lifted off the steel wire support, and carried onto a seat of asbestos or slate. Either of the foregoing is to be preferred, to iron, because both are nonconductors and will, therefore, exclude the possibility of too sudden a thermal change, and probably hair- like fracture of the mold. It nuist be understood that at no time has the temperature of the flask been raised to a i)oint that would make it red hot, or even beyond that. The wax advocated for use in this book will volatilize and disappear at such a comparatively low temperature, that it Avould be folly to subject the mold and, therefore, the plaster therein, to any- uncalled for degree of heat. It is well to remember that the le'ss heat Ave employ, the stronger our mold will l)e, and the greater its resistance to in- ternal i^ressure, and the less distortion Ave shall cause inside of the mold. The flask is now alloAved to gradually cool doAvn until it is the same temperature as the air in the room, Avhen it Avill be ready to be put into the seat, on the machine, in order to re- ceive the metal. CliAl'TER XII 'mis C'AS^I^IXd OF THE :\I()LTEX I\rETAL IXTO THE MOLD We are coming- to the elucidation of tliat i3art of the tecli- nic of the casting of inlays, Avliich has proved the most active l)attle-gronnd for the many and various ojiinions of as man}^ writers njDon tlie subject. The hot mold or tlie cold mold, the expanded mold or the normal mold, questions -which, in the minds of some, occupy a i^lace of prime imj^ortance in the art of casting, and I Avould retrace my steps a l)it and bring again before you some of the telling points in the sequence of their occurrence in these vari- ous chapters. Let us all remeni])er tenaciousl}^ that we are doing our work in a room kept at a given temperature; all our things, instru- ments and materials, as well as the probable patient and the tooth, are in that room and subject to that temperature. The cavity is prepared and we are ready for the making of the wax inlay. The wax is softened and put into the cavity, cnid it is caused to harden under pressure; it is chilled, Avhile a force greater than the intramolecular attraction of it, is upon it to prevent any change of bulk or form. Once cliillcd 1(^ jjrojxM- size and tVictional lit of cavity, no change of form or bulk of the Avax can take ])lace at that tem- perature. The car\iiig is (•()ini»l('t('(l and ilic iiday is invested in a compound; the powdci- and llic li(|ui(l, A\liicli mak'e up this com- pound, are placed in a bow] oi- mixer, at the same temperature which the wax inhiy has been subjected to right along, and which tempei'ature it can not change. The coni])onnd ('()i]1ains so lillh' of Ihc active ])laster, that practically, no heat is cvoKcfl (hiiiiig the ])('riod of crystal- 178 CAS'I'IXC MOI.TKX .MKTAF. INTO .MOIJ) J 79 lizatioii of Uk' mass. 'I'lic wax patlci'ii in lliis mold, llierefore, lemaiiis iiiichaiiged. Once the mass is eiystallized around the nnchanfted wax pattern, we are justified in our fixed belief founded uj^on sound reason, that we have a normal mold. A fixed belief, rounded uj)on sound icason, means nothing" short of definite knowledge. AVe, therefore, know that up to the i^resent point we have done nothing toward ereating or call- ing into existence, any condition at variance with these that are essential to keep our wax pattern, and tlic mold in wliicli it is, unchanging as to bulk or shape. The flask is now placed in the projjer position, within the furnace, the heat is applied and gradually increased, until the wax lias l)een volatilized completely; and with the application of the heat, comes the change in the size of the mold and flask, which gives at this time a distorted mold. Note the word dis- torted, for this is just what I mean to convey to you; the inlay is not made larger evenly or in the same ratio in all directions. Eefractory materials shrink or exjiand, as the square of the mass, but if we remember that our wax i^atterns are not cubes, or balls, or just fiat surfaces, or star-sliajied dreams of even-jDointed bliss, we shall realize that perhaps at one point of the circumference of the wax of the mass surrounding an inlay, we may have a compound one-fourth inch thick and one and one-fourth inches high ; while at the next point of the circumfer- ence of the mass, it will be tliree-eighths inch thick and one and one-fourth inches high; at a third point of the circumference, it may l)e one-half inch thick, and one and one-fourth inches high; while on the crucible side we may have it one-fourth inch high around the entire circumference, and one the reverse side of the flask, it ma}^ be a solid block of investment one-fourth inch deej) l)y one inch in diameter. Where the compound is thinnest in bulk, it is nearest to the brass flask, and the influence of the metallic ring, as an aid in distorting the compound more at that point, will, in a hot flask, make itself felt most decidedly. If we admit that the exjoansion of the mold at the thicker part of it is less likely to l)e influenced by the metal ring (a reasonable admission), and that, therefore, the expansion of the part of the mold would be more likely to take place in ac- ISU CAST c;()Ll) AX I) rOltCELAlX IXLAYS cordaiico with tlie recognized laws wliicli govern tlie minerals that make up the mass, then we must have an exj)ansion of this mold which is of ver}^ marked inequality; in other words, a distortion. Into a mold so distorted, these hot flask adherents then cast their metal, and the result is an inlay which is as imequally enlarged as the mold was unequally distorted. All the disking and stoning, and cutting and trinuning, can not Ining this casting l)ack to the exact form required for that cavity, for clearly no means at our command can make this metal assume angles, lines, points and surfaces, the same as to size, proportion, and direction as those possessed hy the wax pattern. The fact tliat some men do put these inlays into cavities proves nothing except that they are content with the results they obtain, and that, of course, is no proof of the correctness of their method. The men who realize the truth of the foregoing, will, after the complete volatilization of the wax, allow this flask to resume its normal size, and the mold within to come hack to its original proportions. This can only be acconq^lished by allowing the mass and flask to become stone cold; that is, resume the room temperature. The cohl Hask adherents, realizing that the correct com- pound they use for investment is so well balanced in its com- ponents of plaster and silex that the expansion of the latter nullifies the contraction or shrinkage of the former, are content to carefully and tlioi-oughly volatilize the wax and allow those two comi^onents to return to their oi'iginal condition, by allow- ing the mold and flask to rid itself of its heat. Tlius they ob- tain, after the volatilization of the wax, a mold of exactly the same size as the wax ])att('rn, \\liicli llicy pnl into it, and which has now disa])])ear('(l, and this mold is of the same temperature now, when it is i-cady for the metal, as it was when it contained the wax pattei-n. It was unahic to alter its shape and ])i()|)or- tion then; it is unable to remain distorted Avhen allowed to cool. The accession of the heat which caused its unequal distortion, AvilJ, by its gr;ulual disap])earance, compel the compound to re- sume its normal condilioii. I tVcl thai I can not he loo cmplialic CASTINC .MOI/I'KX .MKTAl. IX'IO .MOlJi 181 about this. Xot only is the cold llask in liai'nioii\' with the ])liys- ical laws, but it has |ii-o\(mI itscll' coi'i-ccl in this ])i'aeti('al woi'k' and clinical cxpi'iinicnts. TIicn' w ho rail against it liavc slij)])e- a;4ain, woi'k out excry stej) carefully, and fol- low directions iin])licit ly. It anIII i>ay; I'oi- they will obtain re- sults that are correct, and 1 am wiliiiiL;- to assume that they are eager for such results. A cold llask it is then, at least for the confines of this xolunic, and t'oi- those who desire to follow the technic outliiuMl licrcin. Perhaps it will he as well to say here, that unless every step of this technic he carried out as outlined, 1 consider myself absolved from any responsibility. I willingly and confidently promise results, providing the reader will follow instructions to the letter, but 1 will not submit to any deviation on the irdvt of the reader, nor will 1 brook any su])stitutions for portions of this technic; no short road to Rome — no better or quicker method in part. If any supplanting of method be done, it must be so supplanted as a whole. This technic interdigitates and dovetails in every step or degree, and it has l)een carefully worked out to do just that. A change in any i)art means a disturbance of the equilibrium and indifferent results — something to be avoided. SUMMARY FOR, CHAPTER XII The Drying Out of the Mold and the Burning Out of the Wax Model 1. Describe a simple licatiiifj apparatus for use in the burning out process. 2. Describe the Platcheek furnace. 3. Describe tlie uiaiiner of manipulating the flame to iiisurc the proper dry- ing and burning out witliout brinuin"- the flask to a red hot condition. CHAPTER XIII THE :\IETALS FOR THE IXLAY AVORlvER Tlioiigli gold, X'lt^tiiiiiiii, silver, copper, and all tlie metals of the i^latinum groui) have their measure of apj^lieation in inlay Avork, only gold and jjlatinnm will ])e considered for the pur- 2)ose of this work. I want to lay stress npon the fact and have it clearly un- derstood that when I sjDeak of metals at all I speak of them in a pure state, or rather in a commercially pure state. So that in considering gold, it is understood to be pure gold, 24 carat fine, and in considering j^latinum it is understood to he pure plat- imim, soft platinum, as soft as the refiner can furnish it in sheet or foil state, as devoid of iridium as it can he made. AVe have been in the hal)it of speaking of metals as royal or noble metals and base metals. Royal metals are capable of being separated from combinations with oxygen by merely heating them to redness. Base metals are those wdiose com- pounds with oxygen are not decomposable by heat alone. Gold and platinum belong to the royal metals. Gold: symbol Au; combining weight 197.7; fusing point 2004° F., 1050" C, specific gravity 19.3 to 19.5. Platinum: symbol Pt; combining weight 193.3; fusing i)oint 3225° F. to 3425° F., 1650" ('. to 1775'^ c] specific gi-avity 21.5. A quantity of i)ure gold depending U])()ii the needs of the case, a cei'taiii amount of vei-y tliinh^ rolled out platinum, a seasoned cliai'coal block, a mixture of potassium nitrate and boi-ax, two-tliiiefor(^ ])i-oceeding with the aj^plication of Fig. 169. — A charcoal block with a depression in it to act as a crucible. A copper wire tied around this block will prevent such accidents as the sudden dis- ruption of it when subjected to great heat at one point. These blocks should be thoroughly seasoned, as explained elsewhere in this book. the nitrous oxide blowi)ii5e to the gold, platinum must be pre- pared tirst by cutting it in very narrow strips, not over Mg or %2 of an inch wide, and as thin as it can be obtained. The nec- essary cpumtity of this material is now i)laced upon a sheet of white paper, so that the individual ])ieces may be easily dis- tinguished. AVe are now ready to proceed with our melt. The city gas is opened, and the tlame is lit, the nitrous oxide cylinder valve is opened and the gas is allowed to How into the mixing cham- ber to unite with the city gas to give the necessary heat units, so as to efficiently bring the metal to the required temperature. IS-i CAST c;OLL) AXJ) J'OKCELAIX INLAYS Tlie liottest part of a nitrous oxide tlaine is at llie first tliird of its exit from the l)lo\vi)ipe and the successful coml)ustion of nitrous oxide and city (i,-as is one that consists of a continuous pencil of a clear, bhush green tianie, covered by a short mantle of red rays, sparingly distributed round the bluish green tlame at its immediate source, and reaching onh^ for al)Out % to 1 inch of its k^ngtli. The wliole (hime for the melting of the metal in the crucible should be al)out 4 inclies long and this necessi- tates the reduction of the supph^ of city gas to the requisite amount. The operator must now don his amber-colored glasses and the flame is now played on the gold contained in the crucible, the flame being no more than V/2 to 2 inches away from the gold. The application of the flame must be constant, the hand nuist be steady, and there must be no drafts in the room. The first sign of effective work will manifest itself in a loss of def- inition as to outline and boundary of the various pieces of gold. They will ai^i^ear to collapse, to give up their identity and will go from a state of redness, from a shapeless to a spheroidal mass into a state of incandescence, thence to a violet-colored, heaving mass, in which the repelling and the attraction of its component molecules seem to be alternating phenomena, fol- lowing each other with a rhythmicity and a i^eriodicity which inight be definitely measured if one felt so inclined. At this time, a piece of the narrow platinum foil is grasj^ed with the platinum-tipped foil carriers and fed into the still constantly boiling mass of gold, until it has been completely absorbed. This process of feeding the platinum is continued until tlio required amount of this metal has been taken up by Ilic laigci' mass, after that the flame is still held over the danc- ing llnid gold and it is kepi in n \-i()l('iil stale of agitation for a ])eriod of time, varying directly as tlie ((uantity of metal being handled, the periods l»eing about as lollows: 1 oz. of au alloy containing jjure gold and 2]-2 to .") pei- cent of ])latinum nmst be k'ej)t after tlie entire amount of platinum has been tak'eii up by the molten mass, in a state of constant agitation for at least two minutes. Tlie ailo\- will be nnieli more homogeneous if this pei'iod is prolonged. If the allo\- contains a gi'eater percentage of platinum, hetween T) and I'l per eciil, the pei'iod of time I'O- .MK'r.\i>s I'Oi; TiiK l.\•|.A^■ wokkki; 185 (jiiircd I'or coiislani ;i,ii,itat ion should he no k'ss than live min- utes. If ilie alloN' conlains a (|uaii1ily of ])latinuni '••reater than 10 pel- cent and up to 1.") per ccnl, the jieriod of a^'itation is from scNcn 1o ten ininulcs. The alloy must ))e allowed to cool artci- thai, must he i-oMcd out into sheets, cut into small sections, a.^ain icmelted and a,i;itate(l {'ov I'l'om seven to ten minutes. In a certain qualitx' ol' castin*^' jL-old used which among other things contains 19 pei- cent i)latinum, which ])latinum in turn contains 2 ])er cent iridium, the mass is fused, the i)latinum is fed in, then tlie entire mass is agitated for lifteen minutes, an ingot is made and this i-oHed out into sheets, then remelted, etc. This jjrocess is repeated four times and the period of agitation is longei' each time, so that at the fourth time the period lasts be- tween twent^^-tive and thirty minutes. AVlien the jjeriod of agitation has i)assed, the flame is ex- tinguished, the mass is allowed to cool, and it is not to he touched until it has thoroughly crystallized, when it inay he l)icked up with the platinum-tipped foil carriers and jjlaced into a hydrochloric acid hath, and then rinsed with plenty of cohl watei-. If the quantity of metal is an ounce or nearly an ounce, it may he divided into four imvt^ by using the cold chisel and the hammer. The anvil nmst he clean and a sheet of Avhite i)ai)er, or l)etter, cardboard, nmst l)e ])laced ui)on it. AVlien the nuiss has been separated, each individual piece must be first boiled in nitric acid, then washed in water, then melted in the charcoal l)lock with the nitrous oxide blowpipe, agitated for a minute or so, allowed to crystallize, transfen-ed to the hydrochloric acid, again thoroughly washed in water, and put away for future use. No surplus of any casting should be used again, unless it has been retined by thoroughh^ fusing it and si3rinkling it lib- erally with the powders contained in the receptacle holding the potassium nitrate and borax. The melting process from then on is continued as is the period of agitation, as previously out- lined. Gold for inlays for j^atients Ijetween twentj^-five and forty- five years of age, where teeth are in fairly normal occlusion : Pure ooM 4n.')i/^ grains Pure platinum HVi " 18G CAST GOLD AXn roRCELATX INLAYS Cold for inlays for ijatients wliere teolii are in malrelation and where the stress of occlusion is varyin.i;- in direction and very intense : Pure gold 450 grains Pure iilatiiuiiii 24 " Gold foi' inlays for teeth in normal occlnsion: Pure gold 4921/^ grains Pure idatinuiu 7^2 " liuld for inlays for teeth that are very frail: Pure gold 432 grains Pure platinuu] 38 1/2 " Pure silver 91/2 " Ciold for cast bases: Pure gold 456 grains Pure platimiiii 24 " (iold for saddles: (1) Pure gold 384 grains Platinum 2% iridium .... 72 " Pure silver 18 " Pure copper (5 " (2) Coin gold 432 grains Platinum 2% iridium 48 " SUMMARY FOR CHAPTER XIII The Metals for the Inlay Worker 1. What metals arc comm.only tisccI by the iiday worker? 2. What are the materials and the instruments necessary fo maki' a com- plete nictallurgic equipment? 3. In Avliat form should gold and platinum, rcsiicctively, be used? 4. Descrilic the making of thf melt. CIIAITKK X\V THE CASTJXC OK ^FUE MOLTEX MKTAL INTO THE MOLD AND A (OXSIDERATIOX OF THE VARIOUS ,A[AC^HIXES EMPLOYED At tliis stage of tlie work we are ready to ])iit our cold llask into tlie seat of the iiiacliine with whieli the casting- is to he done, and hefore we do tliat k4 ns consider and carefully examine some of the things that have l)een said in regard to the casting of gold. AVe shall, however, first establish the truth of the fol- lowing statement : "All metal castings are made under jDressure." It must be apparent to anyone who thinks, that even if no apparatus of any kind is used in forcing metal into a mold, there is still the ])ressure of the falling metal to be accounted for. It matters not what we call it, gravitation, or anything else, the fact remains that what we are trying to put into the receptacle has some weight, and if this weight is great enough to overcome the resistance of the air in the mold, and if the mold be joorous enough to allow that air to escape, then we shall have a casting, and the very fact that we get a casting, proves that the resistance of the air was overcome, and to overcome resistance we must have pressure. Of course, the relation l)etween the size of the gate in the mold, and the success of the casting, with what may l)e called the inherent jjressure of the metal, is a factor to be carefully taken into consideration. The gate must be larger in casting by this method than it would have to be if we had the aid of some outside agent to increase the i:)ressure, and confine it to a circumscribed area. It is not advisable to use this method in casting any of the royal metals, because of the excessively high fusing point of these metals, and the ahnost impossible task of keeping these metals at a temperature required, in order to have them fluid 1S7 188 CAST (.lOLD AXl) roiU'liLAlX IXIAYS enough for a long enough period of time to conix)lete a casting by this metliod. It lias been and is being enij)l()yed in casting low-i'using alh)ys, used in the laboratory for lower dentures. Most men Avill be familiar with the metliod; that is, the preparation of tlie model; the making of the wax pattern, with its tAvo in- verted, cone-shaped extensions at the condyles; the investment of this model carrying this 2)attern into one-half of a sj^ecial tiask in such a manner that only half of the wax j^attern and inverted cone extensions will be embedded into the plaster and sand, the su])sequent lubrication of that half of the investment and wax, and tlie placing and filling with plaster and sand of the other half of the iiask, the drAdng of the flask containing the invested i^attern and model; the opening of the flask and the boiling out of the wax; the careful drying out of the mold until th(^ mirror test shows it to be devoid of moisture, and finally the melting of the alloy in a suitable crucible; the as- sembling of the two halves of the flask, and the pouring of tlie molten alloy into one of the funnel-shaped openings at one side of the flask, until we see the metal rise in the funnel-shaped openings at the other side of the same flask. If the side of the flask which contains the funnel-shaped opening in which the metal rises, were longer by, let us say, an inch, than the side which contains the funnel-shaped opening, into or by way of which we pour the metal, we could continue the pouring until the metal on tlie escape side had risen a full inch higher than the metal on the intake side. If there were no inherent pi'essure in the metal being poured into the intake side, til is could not take place, and it is also true that this pres- sure is as the weight, and is, of course, partly subject to the same laws as those wliicli goNci'ii railing bodies. I lliiiilv- it is pretty Avell proved that casting as described above, is ])ressure casting; and I think also that T can save s])ace and time l)y simply stating tliat the metliod described above is entirely and absolutely unlit for the casting oi' inlays, willioiit goin;^- into an_\' lengthy dissertation as to why this is so. What is ti-ue of the simjile j^rocess above descriljed, holds good in dental casting by iiieans of centril'iigal force, Avhether \\'e make use of one of the een t I'i Cnual castinLi- nia<'liines sold CASTIXC .MOI/I'KX .MKrAL — M A( ' 1 1 I N KS KM |•|.()^ KD 189 for tliis i)iirj)()S(', or sim])ly swiii^' a hiicUct (M^iitaiiiiii;;' tlic mold, and the molten metal in a circle with sufificient rapidity to cause this molten metal to hui'v itself in the space provided in the mold. That this <'enti'iru<;al t'oi-ee innst he convei'ted into pres- sure hefore it can canse the metal to seek the cavity in the mold, is proved by the fact that all forces tinally expend themselves in i)ressure of one kind or another, so that a casting- made by the centrifugal method is essentially a pressure easting, and if this centrifugal force could in any way be definitely confined and doled out in given, definite, and measurable quantities, it would have i)oints in favor of its use. At present I know of no apparatus in which this pi'iiici])h^ is utilized tliat could be said to be deiDcndable enough to warrant its use in the casting of gold inlays. No claim made ])y the vendors or manufacturers of these centrifugal casting machines has been sustained. The quantity of the force, and hence the amount of pressure used, being unknown, the best one can say of the possible result is that it will be doubtful. I used one of these machines alongside of many other makes, and after careful, conscientious efforts, I was forced to the conclusion that no accepta])le inlay can he made by this process. The machine has its use perhaps in the arts and crafts of jewelry castings, and in coarse laboratory work, where things cast may afterwards be filed out to definite measurements, but it is not to be considered for inlay work. The most commonly employed centrifugal machine consists of a base with a cenliifugal j^ivot, to which is fastened one end of a coiled spring and a flywheel with a recess in the under side. This flywheel is mounted movably upon this central pivot of the base, and the coiled spring, one end of which is fastened to the central jiivot, is attached at the other, or outer, end to the tly wheel, and enclosed in the recess of it. Externally to the frame or base is a bar which actuates a leather-covered lever arm which coacts with the flywheel to hold it in a given position after the spring has been wound up. This inakes uj) the en- closed mechanism of the machine. The exposed jjart consists of an arm, fastened to the fly- wheel by means of screws, entering a small cylindrical por- tion of this flywheel. A i)ivot about three-c[uarters of an inch ],[){) CAST UOLl) AND PORCELAIX JNIAVS in lioiglit, rises from tliis crossann and serves as a handle to wind np tlie spring by rotation of tlie fiywlieel. On eacli end of this crossann, is a lieaded rivet npon Miiich a sliding ad- justable arm is carried, and one of these end arms carries the tray which contains the flask and mold, while the other one carries the counterbalance. When the mold is ready to be filled, the flask is slipped into the carrier on the end of the mold arm. The sj)ring hav- ing been wound, the adjustable arms are set at right angles to the crossbar, or very nearly right angles. The crucible in wdiicli the gold is to be melted is placed upon the carrier immediately in front of the flask. The gold is melted, and when it boils, the flywheel is released, which sets it in motion, which motion is transmitted to the crossann, and from it to the end placed ad- justable anns, which immediately straighten out, with tremend- ous outward motion, and this forces the molten metal into the mold. In a few moments the maximum velocity will have been i-eached, and from this point, the sj^eed of the machine will decrease. It may be either allowed to spend itself, or it may, after one and one-half minutes be stopped l)y pushing the leath- er-covered lever against the flywheel. The manufacturers of this machine claim that the force may be modified by fewer windings of the spring, and while this is undoubtedly correct, the pressure produced remains indefinite and, therefore, not suitable for our purpose. Willi tlie greatest care used in every step of the work, all iidays made were more or less irregularly distorted, due, no douljt, to a forced readjustment of the walls of the inside of the mold, this readjustment being actuated by the impact created first, by tlie violent straightening of lli<' ai-iii, and its consequent sli])ping upon the i)ivot, and second, by tlie impact of the metal against the wall of their frail investing comi)ound. Wliile the defective investment may be eliminated, the agi- tated mold icmains as a permanent deleterious agent in the ]n\'^- enl macliine, and il seems (h)ul)trnl il' it ever can be remedied. If tlus njacliine is to take a. lasting j)lace in the art (.1* casting inlays, I Avould suggest that a (h^viee be added to it that would enable llii' opei'aloi' lo so wind llie spi-ing, and so set the CASTIXC .M(H;i"KX MI/IAI. — MACIilXKS K.M IM.ONKD IDl llask that both the iiioiiiciituiii ol' the ilywliccl ami tlie sliock w itii w liicli the flask is caused to straighten or throw itself away IVoiii the center, may he ineasnred. Tliis is not at all inipossihle, and simply means a year oi' so ol* constant ex])ei"inient and mathematical dcdnction. 'Plic mannl'acturers wonM tlien liave a product which they would he justified in offering to the pro- fession for accuiate work, jn-ovided, of course, that their experi- inents did not coin])el their honest conclusion that at its hest the machine would he unlit for inlay woi'k. liegardless of any assertions to tlie contrary, most vehe- mently made ])y the maruifacturers of the vacuum machines; they aic nothing else than pressure machines; and in order to prove this, it is only necessary to c[Uote a small ])ai-t of tlndr glowing literature full of little jokes. ''Not the slightest fraction of an ounce of artificially pro- rhircd pressure is applied at any stage of the casting operation, A\lien an Elgin is the apparatus used. There is not the slightest fraction of an ounce of artificially produced resistance to he overcome, hecause the air in the mold is removed in advance, and is not sid)ject to compression. "Pressure is not necessary hecause there is no resistance. There is no resistance, the air necessarily and naturally is re- moved in advance of the entrance of the metal, through the pores of the investment material which are plenty large enough, no matter how small they may he, to permit the instantaneous passage of the air in response to the pull of a vacuum formed beneath the mold, a pulling force more than double normal at- mospheric pressure." (Dental Casting, 1912, The Ransom & Eandoljoh Com^iany.) If any evidence he needed to prove that the suction ma- chines are pressure machines, the little hooklet containing the ahove quotation, and many other sayings quite as contradictory will supply that evidence gratis. Just think of this wonderful pulling force, dragging on the vitals of the mold, and keeping up this drag even after the gold begins to enter, with a force equal to douhle that of at- mosjjheric pressure, to wit: thirty pounds to a square inch. Of course as fast as this machine sucks the air through the mold and creates a vacuum, the atmosjjhere ahove would 191^ CAST eiOLL) AND POltC'ELAlX IXLAY.S 1)0 inert if it did not i^usli or ijress the gold into tliis vacuum much abhored by nature; and because this j^ull is so strong, in other words, because this sucking apparatus is so voracious. Fig. 170-J. — The Elgin vaciiuni cnstiiig macliiiic and llasl<.s. Fig. MOIi. — SaiHf iiiarliiiic us in l-"ig. I7(i,/, ri'mly Inr casting. th(! aljused and harassed aliiios])li('i(' nhove must exei-t this tliirty pounds to the sriuarc inch in-cssiiic i/alrns rolens. All 1lii> linn' IIk- imoIcciiIjii- inlcuritN' of llic mold is being CASTIXd MOI/l'KX .MKTAl, MACIIIXKS KM Pl.OVKI) 193 attacked l)y this plus siidion in oidci' to allow tlie gold to enter witlioiit any diu'ess exce])t the doultlc atmospheric pressure, the ])iill of the ])Ius suction e(iuals. it will he well to note tliat the natural atmospheric pres- sure ui)on the earth at oui- level is al)out fifteen pounds to the square inch, and anything ahovc that is an artificially produced ])ressure, whieh makes their statement in the heginning of the quotation, seem veiy far from an accurate scientific assertion. To cite another quotation with the reader's indulgence, — hut first the digression to recall to your mind that we must thresh these things out to settle them, for at least some time to come, — it will ])e well to quote from the same booklet, page 4, beginning on line 25: ''In casting by other than the vacuum method, the excess metal in the crucible is the first to solidify, tliere])y shutting off the pressure. Pure gold, especicdJi/ slirinks in the process of hardening, and with the excess solidified, and the pressure removed, the metal in the mold contracts to the extent of the sJirnikar/e. "With the Klgin, the first portion to harden is the metal against the outer walls of the mold, and the last, the excess in the crucible, while in all other forms of cdsthuf, the process is reversed. "In using the Elgin api)liance, the excess can be kept mol- ten, and the suction maintained, as long as required for the metal to completely harden in the mold. Simultaneously with the shrinkage taking j^lace in the mold, the vacuum draws metal from 5'^//^ molten excess to fill the space left by the natural shrinkage." The colossal imi^ertinence of sending a booklet containing such statements to men who are supposed to have had at least a primary lesson in metallurgy, can only be accounted for in two ways : It may be that the man that wrote this statement in the Koranic booklet really l)elieved he was telling the truth, and it may be that if he knew he was Avrong, he figured that none of the men would read it with enough attention to find the pig, and if they did, they would not know the difference anyway. I have seen beautiful jewelry, such as elks' heads, cast liU CAST GOTJ1 AXD ronCFJ.AlX IXT.AYS Upon an El^iu iiiacliine, hut 1 liavc iicvor yet in my ])ra('ti('e, l)fcx^n called ui)on to insert an elk's liead into a patient's tooth, to take the i)lace of an inlay. J have seen (Jreek letters and coiled springs and scimitars Avhich were sucked into an Elgin and atmosjihered twice over again, hut none of those things have ever heeii called ui)on to measure up with any mici'ometer measurement. It will he well foi' the student and i)ractitioner to hear in mind that we are called upon to inlay teeth, and to inlay them with mieroscoi3ic correctness. True, we can appreciate fine jewelry, nice rings, decorated with figures or hieroglyphics, and no douht, if we ever leave our profession to enter the field of tlie art metal worker, these machines may have their uses, hut so far as I have been ahle to deternune, they are failures, and an ordinary little swage, with its air-comi^ressing interior, is to he preferred. The vacuum machine is a pressure machine; of that there is no douht, and if it were not such an inverted i^ressure ma- chine, it might he useful. I take it that the reader Avill have come to the conclusion that I am an advocate of a direct pressure machine, and this conclusion is sound. I have my reasons, too, for jDref erring and using and advocating the direct pressure machine, provided it is the right kind. The right kind of pressure machine is one which will perform the following service: It must ena))le one to melt tlic gold in the crucihle of the flask, hefore the investment in this flask gets hot enough to dis- tort the mold, and this means that it must have an oxyhydrogen or nitrous oxide hlow})ipe. It must furnish me with a means to definitely know how mneh ])ressure 1 am using foi- casting, and I nuist he enahleil to sustain that pressure at w.ill; and I must he enahled to apply that pressure at the psychologic mo- ment. These things a pressure machine mnsl do or it will he use- less. AVliat otliei- things it may do in addition to those men- tioned, are a inatter of refinement of detail and economy of operation, and are of course factors wliicli det<'rmine one in the purcliase of any mcrcliaiidisc, hut iliey aic not al)Solute CASTIXC .MOLTKN MK'I'AI. .MACIIIXKS K.M IM ,( )^ Kl ) ]!).") essentials lo perTccl rcsull.s wliik' llic lirsl iiieiitioiicd things arc a))S()liil('ly so. Xow. hd'oi-c lakiii,!;' U)) direct ])ressure iiiacliiiies, suppose we (luiekly. hut t liorou^lil y, coiisidei' some of the ])lieiioiiieiia Avliicli take place in tlie castiii,!;- of ;;()ld iiiidei' jjivssure. Tile rollowiiii;,- is a ([uotatioii in ])ait IVoiii a treatise wi-itteii by ('. .]. ('lai'k, of Cliiea^o, Illinois. "Foi- countless a;;'es tlie luatter of tlie eai'tli existed in a Hiolt'ii state, <;radually coolini;- and sliiiidvin^- until tlie surface became I'id^^ed and the intei'nal molten mass ])ecanie encapsuled hy a ci'ust. As the shrinka<;e continued, matter was calh'd upon to sui)i)ly the deliciency, and the crust Ijcinf*- solid and ri^id, and held by the j^ower of cohesion, the j^ower of the centrifugal force was the greatest at the greatest circumference, and, of course, the portion of tlie revolving s])here that offered the least resistance (tlu^ jjoles) succuniljed to the demands of the intei-nal shrinkage and were drawn inward; and so we find the eaith llattened at the poles. "The cooling of a metal in a mold, wliih- not exactly similar, is strikingly analogous to the cooling of a ])lanet or the earth on which we live. "Matt«u' is never at rest, the atoms comprising the mole- cules revolving around a connnon center, forming a miniature solar system, are in a constant state of agitation, moving rajoidly around in their medium in ether, and confined in their move- ment to their limited space between their fellows. "The outer surface of a mass of matter is the first to be susce])tible to any thermal change, the eifect being transmitted to the center, and if this thermal change of sufficiently bigh degree to change the state of the mass fi'om the solid to the liquid, or gaseous, or vice versa, the su]7)lus is the first to exhibit these manifestations. "Let us suppose a cross section of a gold plate is being sub- ,iecte(l to heat of sufficient degree to induce a change in its l)hysical structure, the atoms of the molecules revolve more raj)- idly than before, become more diverging in their tendency, de- scribing a large circumference about their common center, the molecules increase in the same i)ro])ortionate volume, and their mutual ])()\V(M' of cohesion diminishes. This allows the mole- 1i)(i CAST (iOLD AND I'OIU'KLAIX IXIAYS eules to sej)ai"at(.' more widely, and pennits of a ^roatei' latitude in wliicli to exercise tlieir mobility. As the atoms are whirling" aliout tlieir common center, the molecules are revolving and revolving also about each other, generating centrifugal force to such an extent as to overcome the force of gravity, and with a tendency towards projection in every direction held in re- straint only by the still active though much weakened power of cohesion. "This causes some molecules to l)e lifted above their fel- lows, and as the heat increases, the mass begins to assume a globular shape or form and jiresents a panorama of rhythmic harmonious action. "Xow if the heat l)e withdrawn, the revolutions of the atoms about tlieir common centers decrease, and as their momentum gradually diminishes, the atoms come into closer proximity, the molecules decrease in volume, the i^ower of cohesion increases, tile iiiutual attraction of the molecules becomes more intense, exhibiting more influence than the force of gravitation, and the congealing mass of metal retains more or less of the glolmlar form, the molecules being caught on the act of falling, much the same as water is caught, and held in the formation of an icicle. "The duration of time in which the metal is transformed from a molten to a solid state is exceedingly short, and the fact that the metal retains enough heat to maintain a red color for a time, furnishes no scientific proof that the metal in the mold will shrink for flic metal that remains in the criicihle aucl the iiK'fat ui the mold encounter conditions in hardening which are (lid metrically opposed. The metal in the crucil)le is confined by no walls, and the pressure on it ])eing from without inward, has no such effect, as on that confined in the mold, for the reason that the hydraulic ])ressure that the confined gold is subjectcyd to, forces the inetal froin the ceiitei', outwardly as long as it remains molten, and thus it is pressed against the cooler walls wliei-e the crust as described is formed, and which will register a density of 19.45 against 19. Hi of tiiat i-emaining in the crucible; and there is no inherent I'oi'ce or physical ])roi)er1_\- in the nietal itself after being cast und<'r pivssure capable of suggesting its density to any fui'ther - dilTcr widel>- in the i-csult that one can accomplish wit h 1 hem. CASTixc; .Moi/i'KX .Mirr.M. — .MAciiiXKs ^;.MIM,()^•|■;l) ID!) Some of the pressure iiiacliiiies iiieiil ioiied >iil»|)l\' tlie nec- essary toi-ce hy IVediii*;- conijji-essed air tliroii^li a cliamlx'r wliicli opens onto and above Die molten mass; otiiei's simj)ly allow a little ('liam))er filled with a moist (•om])i'essi])le substance to be placed ()\-ei' tile ci'ucible wliicli coiitaiiie(l the molten metal, the heat of this metal, acting' ii])on the moistuic contained in the al)ove substance would convert tliis moistui'e into steam, and this steam would supply the ])r( ssure necessary to i)i"0i)el the metal into the mold. 'file most I'eliable of these is one called the Soll)ri<;' machine and is mai'keted liei'e by Ash & Sons. AVcre this machine sup- ])lied with a means for definitely controllinf;' and measuring the pressure, it would j)rove a valuable appliance in one's labora- tory, and he ({uite suitable for inlay work. As it stands today, it may he nsed only for castiufj,' that requires no delinition of tine lines, ani'ocess. It is a machine which enables one to bring the gold to a boiling point in the crucible of the flask before the entire mold has been heated to a point of distortion. It makes possible the use of a small nitrous oxide flame, and it gives off an infinitely greater amount of heat concentrated on the bottom of the metal, than can be obtained with a large blast fiame of the ordinary blowpipe. It is a machine which enables a man to apply a measured amount of perfectly sustained pres- sure at the very luoment when he realizes that he must have this pressure, and the fiame is automatically turned off. as the pressure is applied. I use this machine in conjunction with the entire technic, hf'cause it enales me to do my jvork of restoration in such a. iHcnnier as to maJxP the pr oh ability of recurrent requirement for finiJicr rtl'crf 'ni that direction very remote, if not altogther impossible. This is what the cast gold inlay, conceived and made avail- able for i3ublic use by the discoverer, Avill do, if we are careful to follow the directions in every step of the procedure. It is essential for him who would practice gold inlay work correctly to consider the entire technic as a complete circum- ference of a circle, presenting no break in its continuity. In the center of that circle and responsible for this unbroken circum- ference is the ideal which the inventor conceived and held onto while he thoroKyhly and carefully worked out every phase of tills technic. TIk'I-c can !»<■ no (lucslioii iij)()ii Ibc statement that all of tlii> icvolutionizing ])rincipl(' had its iiiccjttion in, first, a vivid lealization that present iiictliods wciv iiiclficient to stem the tide of tooth destruction; and, second, in the birth of the ideal of what should be done in ordei- to effectually stem this tide. If we place this ideal in the center of this circle, and now divide our circumference into its 360 degrees, and run a radius from each degree u|)on the cii-cumference to the centei-, we shall be in a bettei- ])0>ition to understand just Ik.w closely (le|)en(lent CASTIXC IMOI/l'KX .MIITAF. — MACHIXKS K.MIM-()^'KI) 201 upon this ('()iic('i\tail of the technic, who studied and understood the machine by itself, and in relation to every step Avhich accompanies the us(> ol" all the carefully "[)lanned accessoi'ies, have ])een rewarded beyond their own hoi)es and dreams. They have seen a new era rise in dental 204 CAST COr.D AXD TOIU'KLAIX IX'T.AVS service and dental acconiplislinient, and Avilli the nso of the process, their love for tlie work lias o-rown and with tlie ^rowtli of their love foi- the work, tlie standard of their work has heen raised. Dentist i-y to tlieiii is no more a niei-e jjrofession, a trade, a means of a livelihood. It is a reli<;ion to be cherished and throu^'hly studied for the f^ood it will l)ring to hnmanity; for the aid it will hrinf;- to strng'glin,i;' man, in his efforts to evolve into a ])erfeet l)ein<;-. That is what dentistry means to them; not one of them hnt will affirm and add to this declaration. Fig. 173. — To the right is a vio\v of a small Taggart flask and its crucible former Avhich holds the sprue wire. To the left is the author's barrel-shaped flask and its crucible former and the shortened sprue wire. The amount of refractory compound surrounding the wax pattern is more nearly equal in bulk in all direc- tions in the barrel-shaped flask. Fig. 174. — A special flask, l)unid-sliai)ed, made Ity the author in two sections to be used for large castings. The Taggart machine that takes this flask has been rai.scd from its platform sufficient!}' to provide the necessary room. Is not such an experience an inccntixc to e\'ei-y student, and every dentist who has not >( t ddiie so, to tak'e u]) this ])rocess and study it, and |)ei'severe and follow insti'uctions until it lias lieeii niastei'e(| .' The use of this iinichiiic is e.\cee(lin,i;l\- siiii|»l('. it is a (|ues- tion of knowing what is wanted, of k'nowing that the machine will do all it is int<'nde(l foi", and of testing the machine hefoi'c each casting;' to iiiak'e sure that all is in order. CASTixd .M()i;rK.\ .mktai. — mac ii inks km i'L()\i:i) I'D") rpoii cxaiiiiiialioii of tlic llasks designed l)y Dr. 'ra^*;art, i1 will he noticed that cacli one contains a small lioh^ about the size ol' ll-^an,H(' wiic. '^I'lii.s serves two pui-poses; it forms a vent to i'acilitatc the ('sca]ie of any ,i;as oi- air wliicli may bo present at the time of castiii.ii,', and wliicli mi.^lit offei- a resist- ance to the ingress of the metal; and it serves to show liow well or how ])oorly the ])ressure ft'as may l)e flowing- tiiroiift'h tlie vertical cylinder into the pressure 2)late, and from there onto t he metal. Test the machine out as follows: Place a piece of ru])ber dam into tlie small l)ase of the nia- cin ne, and seat the ilask roundside up into this base; open the valve on tlie nitrous oxide cylinder, and by means of tlie reduc- ing valve, regulate the pressure to the desired point. (Three to five pounds pressure is the right amount for casting inlays.) See that the packing in the pressure head is not dried out and leaky, and see that the four snudl lioles wdncli allow the gas to pass through down onto the flask, are free from any metal or other ol)struction. Xow bring the arm or lever of the machine forward down upon the flask while you hold the fingers of the other hand around the flask so as to close the hole at the upper -psivt of it. The bringing forward and downward of the lever will throw a valve inside of the vertical cylinder which Avill cause the nitrons oxide to descend through it. If you feel tlie pressure of the descending gas upon your finger, which closes the hole in the flask, the machine is in good shape and fit to be cast with. Now alternately remove and replace your finger over the flask opening; the hand upon the pressure gauge should kee]i time with your actions, that is, it should drop to zero as you remove your finger, and reascend to three or five pounds as you close the opening. This will sliow the i^erfect condition of the machine, and you may reh' upon it for the sustained pressure rec[uired for successful casting. Now release the lever arm and remove the empty flask, sub- stituting for it the flask containing the mold ready for casting. Turn the blowpipe until it is at right angles to the machine, and ignite the city gas, opening the city gas valve until you have a 200 CA;^T C.OT.D AXD TOIU'ELATX IXfAYS llaiiK^ alioiit Fdur iiu-lu's loiii;-. X()\\' place a hiitloii of clean gold 1'4 carat line (be sure it is clraii) into a charcoal cnicible placed near the flask (])ut on hrown or l)lne glasses) and open tlie needle vahe on the regnlatoi', which will aHow the nitrons oxide to How into the mixing chamber, throngli which the city gas is (lowing. Tile mixing of the two gases will produce a very hot bine llame abont three-quarters of an inch long, and this flame is directed n])()n the button of gold l)y Inrning tlie ])l()W])i2)e (h)wnward directly over it. In about thirty to sixty seconds, varying with the amount of gold, the flame will have brought the metal almost to the fusing point, liemove the heated gold to the crucible in the flask and play the flame upon it. The tendency of the mass to assume a sjnieroidal shape will now a^jpear, and finally the molten metal will ])resent a glowing shape and the mass Avill ])e seen to move. The gold may now be called fluid, but it is not yet hot enough for casting. If it were cast at this moment a vei-y sluggish mass Avould have to 1)e dealt with, and a very im]ierfect ])iece of work would he the result. This may be avoided by keeping the llame u])on the fluid gold nntil the heat of it has been raised to such a point that the iiK^lecuh s seem to repel one another violently. The molten mass will assume Hk' color of sunlight, with a violet tint in it, the mass will not move from side to side but will rise in the crucible, as if i)uslied uj) from beneath, only to di-oj) back again to repeat the performance. All this has taken less than a minute and at this stage the level- is bi-onghl smartly forward; the ])luiiger and ])ressure heads descend n])on the Hash, the blow])i])e is thrown to one side, the city gas is slint off, the \al\-e which allows the ])ressure gas to ■descend ii|ioii th<' molten metal is thrown open, as the fhisk is sealed, and the molten metal is foi'ced into the mold and lield there under a constant and snstained ])ressnre. The nitrons oxide, ])revionsly usecl to aid in melting the metal, backs up and reenters the (hscending xaKc to sjxMid its force or ])ressure upon the congealing mass. It is unnecessary to again enuinei-ate all the curious molec- ular movenif Ills and atomic agitations which tak'e ])lace on cast- illii'. At best, tliev ;ire 1lie()fe1ic consideration, be;int ifnlK' CASTIXCi -MOI/rKX MKT.M. M \('ll IXKS K.M I'l .( )^■KI » 207 I'cnsoiK'd oiil ; Iml for the iiinii t instances, he round cool eiioiifi'li to grasp witli tlie liaiid, ilhist rat in,u' how little actual and distorting heat entered tin mold during;' the uieitinL;' of the metal. if he llask h;' uncomfoitahly warm, it may be grasped Avitli llie thisk r()rce])s, and eilliei- thi-own into a howl of water, or held under the cold water faucet, until the mold disintegrates and is washed off. A stiff toothl)rusli will remove most of the com- ])Ound around the iiday and sui-plus, and we sliall liiid the cast- ing conii)lete. EEFEEEXCE CONSULTED OX THE EXPAX8I0X AXD COXTRACTIOX OF METALS Clark, D. K.: A ]\ramial of Eulcs, Tables and Data for Mcflianieal Engineers, 187S, *K598. Dana, E. S.: Editorial, Am. .Jour. Sc. and Arts, 1901, vol. clxi. DuBois, A. J.: Elementary Principles of Mechanics, 1894, vol. ii, K4982.2. Howe, H. M.: Metallurgical Laboratory Notes, 1902, K127S0. Hutton, W. S.: Practical Engineer's Handbook, 1896, K5405. Lineham, W. J.: Text-book of Mechanical Engineering, 1894, K4958. Poynting, J. IL, and Tlionip>()n, .T. J.: Text-book of Physics, 1904, K15930.3. Eankine, W. J. M.: Manual of Civil Engineering, 1891, K661. Thurston, E. H. : Brasses, Bronzes, and Other Alloys, 1900, K5.j02..3. Useful Eules and Tables, 1873, K665. Watson, W.: Text-book of Physics. 100.3. K1.5933. SUMMARY FOE, CHAPTER XIV The Casting of the Molten Metal Into the Mold 1. Describe the part jilayiMl by temperature in tlie inlay technic up to the point of drying out. 2. AVhat happens when the .flask is heated ? What effect on the mold has the proximity of the flask to it? 3. What is the result of casting into a hot mohl ? 4. Why is a coid flask necessary and how does it follow the temperature sequence? 2()S CAST COl.D A>;i) roitCLvLAlN ]NLAVS The Casting of Metal into the Mold and a Consideration of the Various Machines Employed 1. What is the principal objection to the nsc of a casting appliance in- volving centrifugal force? 2. Give the reasons for and against the choice of a vacuum machine. 3. "What are the essentials of a casting machine involving direct pressure? 4. How would you prevent the distortion of the mold during the actual casting .of the inlay? 5. Describe the technic of casting in a Taggart machine. C'HAPTEK XV TIIH CLEANSING OF THE CASTING IN HYDRO- FIJ OlMC ACID AND IN A SODIU:\[ ]U(\VKP>ONATE BATH After the casting;' has ))oeii carefully and thoroughly brushed free from compound, it is placed in a rubber cup containino- hydrofluoric acid. The acid will free the casting from any of the silicate it may still have on it. It would be impossible to remove every evidence of this by the use of the brush only. Owing to the enormous amount of heat to which the metal is subjected under the nitrous oxide flame, it picks up a number of mineral and metallic impurities, which, however, are finally forced to the surface of the casting and the crucible side of the surplus. Particularly does the crucible side of the surplus but- ton become contaminated with interfering agents which it j^icks up from the silica, and for this reason it is advisable (impera- tive is the word) not to use any gold for casting unless it is al)solutely clean. It is best to take these surplus l)uttons and define them be- fore using them again. ]\Iore of this later. AVhen the easting has been in the acid at least several hours (it is sometimes best to leave it in overnight), the cover is removed from the hard rubber acid cup, and the casting is taken out with a pair of tweezers and washed, under the faucet, then ])ruslied with soap and watei'. A test tube about six inches long and three-quarters of an inch in diameter, is filled about one-third of its capacity with a saturated solution of sodium bicarbonate, and the casting is boiled in this solution until every trace of the acid has been neutralized. It is important that the acid be neutralized beyond a doubt because of the deleterious effect of the least particle of this acid upon any cement or tooth structure. 209 210 CAST (;()IJ» AND T()i;('FJ>AIX IXLAVS liu])l)er and inclal, and tlie waxes, seem to l)e tli eonly sub- stances wliieli are not attacked l)y it; lienee tlu' use of the rubber eu]) as a receptacle t'oi' it. 1 l)OU<;lit a hard rubber cup about four inches lii^'h, two an bottom. It is an ordinary liard rubber drinking cup and may l)e bought at any rubber goods sliop or large drug store. This is used for the hvdrolluoric acid. y\,r, ]75._Acicl cup, support, ;iiii1 stopper for liydrofluoiic acid, a, stopper; 1), ''" taporiiij4- liard nil.lici- nip; r. paster of J'aris blofk carryiiij;- t-ups. A batch of i)laster of i'aris was mixed to a creamy con- sistency and ])OUi-ed into a papei' hox foui" inches square. Into this mix of plaster, llie nioistenecj ruhWer cu)) was forced to witliin one-lialf inch of 1h<- hoUoiii of the box containing the ])laster, and liie mass contiilning the cu|) was allowed to set. TUv nexl day Ihc ])aj)ei' was I'eiiioved, and the sui'face of CIJOANSIXC TIM'; CASTIXC 211 the plaslcf was t riiiiiiicd lo a si,i;lill\' a|)|)( araiicc After scneral (lays the mass had t lioi-oiii^lily liardciicd and sliniid^ hccause of the ('()ii('-slia|)!' of llic ('ii|), and was expelled IVoni its seat. A quantity of stearine was allowed to come to a hoi! in an a<^"ateware vessel, and the ])lasier I'oi'ni was ])iit into it and al- lowed to l)()il t'oi" one and one-liall* lioui's. H'lie I'esult was a ])las- ter receptacle, liai'd and sniootli, into wliicli the cuj) could he ])laced, and which torni it was i)i'acticaliy iinpossihle to upset. Wlu'u the cup was put iuto the seat, it was tui'iied toward the ri^ht aiul \\as made to lit \'ery snugly. About oue-thii'd of the cu]) extends beyond aiul out of the ])laster, so that it uiay be easily <;'rasped and turned to the lel't I'oi' the ])ur))ose of unseating it. A block of wood was sha])ed to loosely lit the mouth of the cu]j, and into the center of this ))lock ajid going half way through it, a small brass eye was inserted to serve as a handle. A layer of pai'affine about one-eighth of an inch was i3laced over every part of this block, and it was again fitted into the cup. AVhile it was sc'atcd, more ])araffine was added to the circumference of the l)lock, and this pai-affine was allowed to overlap the cuji, thus producing a cover which fitted into and over the rul)l)er container of the deadly acid. Extreme caution nmst be exercised in holding this acid, and care should be taken to guard against the inhalation of its irritating and deadly fumes. The delet(^rious effects from it are very lasting, and I have had some decidedly unpleasant experiences with it, to which I would not care to have any of my readers subjected. Into this cup is poured one ounce of the hydrofluoric acid, wdncli can be procured at a chemist's slioj) in four ounce wax' l)ottles. The wax cork is then sealed into the bottle, the bottle l)laced in a wooden box, and put away. In the average practice au ounce of this acid will serve its purpose for about thi-ee weeks to a month, when it becomes so laden with silicates that it may be i^ronounccMl inert from cleans- ing inlays. The cup is then removed from its seat in the plaster base and carefully filled with water Avhich runs slowly out from the faucet and is allowed to overllow the cu]i. ' 212 CAST COLD AXI> POIU'KLAIX INLAYS This SO ^veakolls tlio acid that it will not hurt tlie basin. AVlien tlie cup has been tliorouglily cleansed, it is replaced in its i^laster seat, another ounce of the acid is i^oured into it from the acid bottle, and the cover is i)ut on as quickly as possible. It is well to take a quart glass jar, hll it with water, and put into the water as nuich bicarbonate of soda as the water will take up. As required, the test tube may be filled and the washed inlays boiled in this solution to completely neutralize the acid, SUMMARY rOR CHAPTER XV The Cleansing of the Casting in Hydrofluoric Acid and in a Sodium Bicarbonate Bath 1. Describe the cleansing of the casting from impurities and give the reason for each step. 2. Describe the making of a receptacle for hydrofluoric acid. CilAPTKIJ XVL BEMOVAL OK Til K EXCESS OF M KTA L, Tl IE POLISHIXC, AND TIIK CKMENTATIOX OF TIIF IXLAY Tlie .sur])lus hultoii is claiiijxMl with a vise, and witli a fine saw tiu' inlay is sciiaralcd I'roni tlic excess l)y sawin^;' tliron^li the sprnc, within a miUiiiR'tei' or two of the castin*;'. A garnet ])aper disc, of iiii'diuni grit, will remove the rest of the sprue, and niediuni-grit ciittk' fish discs rotated toward the margins of the inhiy will pi'epare it for its final ])olisli. Unless the sprue Avire has been attaclied to any part of the occhisal surface, the occlusal part of the casting is not to be touched witli stones, burrs or discs, and it is not to be touched at all until the inlay has l)een tried in the cavity, and the relative occlusion of it determined. The cavo-surfaces of the inlay are carcrully examined with a magnifying glass, and a diligent search is instituted for any irregularities, such as bubbles, etc., which would, of course, in- terfere w'itli the proper seating of the inlay. If any are found, they may be removed with a very sharj) sj^oon-sliaped excavator, or with a X"o. 1 or X^o. 2 round burr, held in the handpiece of the engine. If the area is free from interference, the temjDorary stopping is removed from the patient's tooth, the cavity is carefully examined to make certain that it is absolutely free from any obstructions, and the inlay is put into the cavity and sent home by tajjping it gently, using a stock of hard wood, driven by a few" gentle taps from a leather-covered mallet, Xo undue force must be used; gentleness and perseverance are the agents tliat will overcome the obstacles usually encountered at this stage. AVhen the inlay has gone to place, all margins are carefully examined, w ith the aid of a mirror and a fine exj)lorer. If found satisfactory, the mirror and explorer are laid aside, and while the fingers of one hand hold the inlay in position, the other hand manipulates the right, left, and straight, as well as round ])urnishers, always in the direction with the margins. 213 I'l-i CAST (lOLl) AND roitCELAlX INLAYS If the directioiis liave ))eeii followed, practically no bur- iiisliiiig- should he re({uired, at least not what is generally under- stood as burnishing. There is no occasion I'oi' spinning the gold, and the use of the l)urnishers is indulged in at the margins only to ol)viate the necessity for discs at these ])(nnts. ])iscs sometimes slip and get beyond one's control Tor a long enough time to mar the perfec- tion of a piece. Jf the inlay proves difficult to seat, it should he removed and again scrutinized with the magnifying glass for any ir- regularities or overhanging ledges. These removed, the inlay is again seated, and the process of gently taj)ping it is repeated. Because these inlays fit so closely, and frictionally engage the different walls of the cavity so thoroughly, we are sometimes compelled to seat and reseat them several times before cemen- tation. The burnishers nmst not be allowed to slip off the gold, onto the tooth; the object is ]-ather to run the l)urnisliers ver- tically over the inlay margins, when these are vertical, and horizontally over them, Avhen they are occlusal or cervical; in other woi'ds, when the margins run horizontally across the tooth. With the shar]) jjoint of a i^encil a line is drawn across the heaviest i)art of the inlay, and this line is continued over the tooth. The inlay is removed from the mouth. AVitli a No. 2 round burr a recess is di-illcd on each side of it, as near the mai'gin as the enamel line will pei-niit, and with a ])urr of the same size a similar recess is drilled in the tooth. This procedure gives a saucer-shaped, oi- rather seniiciicnlar depi'ession, on the opposing mai-gin of the inla\', and a con-esponding dej)res- sion in the tooth. The p< ii"il mark' v. ill ^^crvc as a guide for xci'tical dii'cction, while the caNily niai'gins on the cavo-surfaces will determine the dii'ecticm which ihe hui'r will take in the tooth. It will be readily realized thai win ii Ihe inlay is again ])lace(| ill ])osition, the two de])i'essioiis or iccesses on the inlay, will iiKM'l Hie two recesses within Ihe tooth, and an almost cir- ciilar ]•' sistaiK'<' |iini(ni will result upon the application of the roi.lSIIIXC AXIt CK.MKXTATKIX Ol" IXI^AV 215 cement. Such resistance |)ini()iis are exceed iii^^ly sti'oii;;' and very 'ditlficiilt to obliterate, since tlie\' jjossess tlie niaxiinnin hulk' Avlierc tension is <;reatest. Tlie accuracy of the ])r()xiinale relation of tlie inlay, must l)e satisfactoi-y ; tliei'e must be contact with the next tooth, if any be present, il' the iida\' be a compound on'', and il' it be one for any tooth distally to the first bicusjud, tliei'e must be coiitdcl lilies inster.d of cn/fdcl jioitifs. If any delicieiic\' be obsei'ved at these pai'ts, it may l)e rectilied by (h)ul)lini;' a cylinder of i!,()ld toil uj)<)n itsell', and placing- it snui^ly u|)()n the delicient ])art of the iida\' witli tlie smallest quantity of '2'2 carat solder, this cylinder is joined to the inlay ))ro])er, and the bulk of it at that |)oiiit is increased. The necessity tor sucli ste})s, as described immediately al)ove, will become I'ai-ei- as the technic is mastered. It will be recalled that tlie inar,ii,ins of the inlay were ])ol- ished by the use of the burnishers, while it was in the tooth cavit}^ The rest of it is now liuished with tin(> cuttle-tish discs, to be followed by ci'ocus discs. The occlusal surface having;' been found correct, it is ])olislied with small bi'usli wheels and pumice, and finally with felt wlieids, and j^ointed slender engine burnishers. If there has been a sli])-up on the occlusal surface, the inlay is ]3ut into the cavity, carefully seated, and th(» ])atient is asked to brin.i;' the teeth into occlusal relation, while a small piece of thin articulating;" j^aper is held over the tooth that con- tains the inlay. In this manner the interfering high points will be readily noticed and may be removed. The necessity for this ])roce(lure also will grow less fre- quent, as the knowledge of both the process and the technic grows with practice. When the inlay has been sul),jecte(l to all necessary trials, when the recesses have been made, and the inlay has been pol- ished, we are ready for cementation. Use the rubber dam whenever at all i)ossible. It is so much easier to keep the field of operation dry, and the cavity thoroughly clean; steriliza- tion of the cavity is so much more readily accomplished; and the operation is so much more of an assured success, that all arguments are in favor of the rubber dam. In cases in which it is impossible to use the rul)l)er dam 216 CAST tlOLD AXD POltCELAlX IXLAYS (a condition whicli is oxceedingly rare) the clamp may be ad- justed on the tootli to be tilled, or the one hnmediately behind or in front of it, if the tooth be an upper one; or the saliva ejector of Xyman may be used, if the tooth be a lower one. These saliva ejectors were designed by Dr. Nyman, of Chicago, and offer an excellent means of keejjing the held of operation fairly dry with the aid of cotton rolls. Of course, napkins or cotton rolls may l)e used when the clamj^s are being relied u])on to keep the operating area more or less isolated. AVe will assume that we have been able to apply the rubber dam. and thus are enabled to successfully isolate the tooth we are working on, as well as several adjoining ones. The cavity is thoroughly dried, as well as cotton will dry it, a fresh pledget of cotton is dipped into warm alcohol, and the cavity is flushed with this; the walls, as well as the seat, of the cavity are carefully rubbed with this pledget of alcohol- carrying cotton. This is kept up for a minute, when a stream of warm air will dry the tooth. A pledget of fresh cotton is now dipped into a solution of warmed bichloride in ^\,()2 1-250, and this is l)ut into the cavity and allowed to remain there froin three to five minutes while preparations are made for the mixing of the cement. A dry cement slab is essential. Any good reliable cement of an exceedingly fine grain and preferably of brown color will do. A broad spatula of German silver or agate or l)one slioidd be used, and tlie cement must be rather thinly mixed, but very thoroughly spatulated. Spread the mix over as large an area as possible; the more you can spread it out, the thinner the layer, the better the mix, the more thorough this incorporation of powder into liquid has ])een. The inlay has in the interim ])een washecl l)y the assistant or operator himself and di'ied with warm air. The bicliloiidc is l•('lllo^■('d I'l-om the loolli and llie cavity is dried with cotton and again IIusIumI with ah-ohol and dried with warm air. A jifi"y cement tube is liMed with the cement and a thin layer of tlic mix is s])i-ead over the cavo-sui'lace of the iiihiy. roLismxc and ch.mkx'I'aiion oi' inlay 217 The coiitciils of the .jiHN' liihc arc expelled, directing' tlieiii iiit(j the ('a\ity. hy liii^ci' ])ressur(', and the iiday is grasped witli a ])air of tweezers, oi" the fingers, and guidecl to its position over and into tlie cavity. The gi'eatest care nnist Ix' nsed in seating the inlay at this time, and again gentle tai)j)ing ratlier tlian sudden force will aeeomplish tlie desired end. Grasp a ])ointed, notched jiardwood instrnnient of consider- ahle strengtli, in eacli hand, an]i('ll be likely to split undei' stress, bnt the maintenance of nuti'ition is a nuu-h more dithcult thing in a thin layer consist- ing lai'gely ol' inoi-ganic inatei'ial, and whei'ein the major ])art of tlie channels of nnti'ition have been segre!!,ate(j From each otliei* (tlieir anastomoses dest i'()yed), than it would }>o in a thicker mass in which the tnhnles still coinnMinlcate with ( ach other and so cari'V the \i1;il essence to e\'ery cell. The prolileiii of estahlishing a parallel relation between the canal.- of tln-e lectli, witliont desi iiicl ion of too inncli of the \'alnal»le intert w i iiiiii;' nntriiiient canyiiig tnhnles, led the writer to the in\eiilion ol' certain instrnnients which ai'e respec{i\-ely k'nown as a p;ir;dle|onie1er .-ind ;i parallelodrill. ^The nse of 218 SPLixTiXd i.oosK TKF/nr wi'i'ii l^•|>.\^■s 219 Fig. 176. — Showing the parallelometer wrench in position on locking stud. You will note that stud is the only one on the parallelometer which has no clamp connected with it. When the distance which the operator wants to main- tain has been reached, this stud is turned up tightly and the meter is locked beyond any possibility of change. Groat care should be taken by the operator to always see that this stud is loosened before attempting to turn the actuating screw of the parallelometer. This screw has 96 threads to the inch, and could verv easily be damaged or jammed, if the locking stud were turned up tightly and an attempt made to turn the actuating screw. Fig. 177. — In order to make clear the correct position for the various man- drels for different distances, the following cuts are shown for guidance. In the above cut, the measuring posts are in position for all measurements from 6 mm. up to and including 10 mm. Six millimeters is the minimum distance that can be measured with this instrument. 220 CAST (.;()LD AND roltt'KLATX IX LAVS tliesc instriiiiieiits is a simple procedure and makes the parallel- ing of any lumiher of teeth in the arch a definite and mechan- ically accurate task. Let us assume thai we are al)()ut to make a sjilint for the six anterior u])])(m- leetli and that all root work has been j^rop- Fig. 178. — Measuring posts in same clamps as in preceding cut, but with the distance between them increased to. 10 mm. This is the maximum distance that can be measured with the posts in these clamps. Fig. 179. — Showing position of jiieasuriug posts for all measurements from 10 mm. up to and including 2.1 mm. Tiie above is tlie niaxiiiiuni distance that can be measured Avitli the ])osts in these clani])s. ei'ly <'X<'cutc(l, tlial llic canals have hccn filled J'or their gingival lialf, and llial no nndiir n-aniiiig onl of the roots has heen I'e- sortc*! 1o. W'c shall nsc a ITj-gnngc ( llrow n cV: Siiar])) .'>() j)er SPLINTIXC LOOSIO 'I'l'll'mi WITH INLAYS 221 ct'iil iridi()-i)latiiiiiiii wire I'oi- llic ciisiiids and cciiti'als and a 16-gauge wire Tor llic lateral iiicisoi-. ENcrytliiiii;- hciiii;' i-cad}' I'oi' parallcliii,!;' Ilic canals of lliese toctli, we turn oiii- allciil ion to the inst I'liiiicid known as a l)aralleloinet('r and note: Fig. ISO.^Mcasuiing posts in same clamps as in Fig. 179, but "with the distance increased to 40 mm. This is the maximum distance that can be measured with the posts in these clamps. Fig. 181. — When the distance to be measured exceeds -40 mm., the parallelom- eter is reversed and the measuring posts are placed in the clamps as shown above. These posts, as can be seen, are now 35 mm. apart. The parallelometer may be extended to 55 mm. 1. It consists of two r(H'tan<;ular i^ieces of metal, slidaldy adjiistal)le one npon tlie otlier, a screw providing- tlie means of motion. !'__ CAST COIJ) AND I'OltCKLAlX I^•1,A^•S 2. At lixed distaiUH s ii])()ii tlic ])i('ce of metal, certain clamps are j)resent, which will ii])()n l)eiiii;' locked, (h'fmitely liold a givon wire in a fixed groove. i). The ii])])er surface of the engaging sections is accu- rately graduated in millimeters, a constantly augmenting num- l)er of turns of the sere w JKung necessary to traverse a milli- meter space as the first groove upon the tal)le section and the last groove upon the movable section approach each other. This instrument will line uj) I'oot canals parallel to each other, when they are 7 or 40 mm. a])ai-t, and we nmst hear in mind that: First. If we wish to jjarallel the canals of two teeth which are over 7 mm. and less than 10 mm. apart, we clanqo a wire of i'ig. Ih2. — Measuring posts in same clamps as in Fig. 181, but the distance has been increased to 55 mm. This is the maximum range of the parallelometer and will reach from any part of the month to any othfM' part of the mouth. suitahle gauge into the two oj^posite grooves farthest away from the actuating screw. Second. When the canals to l)e paralleled are more than 10 and less than 25 mm. apart, we use the end groove of the stable section as our unit ])oint, and the middle grove of the movable section as oiii- ])oint of accommo!•: 'i'i':i':'rii wriii l^■|>.\^•s 223 ]. 'IMic Icclli iimsl l)c 1 !i()r()ii,i;Iily sc.-iNmI jiikI polished. '2. All suppiiralixc coiidil ions iiiiisl he cliiiiiiiatcMl. ',]. All llic pulps iimsl ])v cxlirpatccl and 11i<' I'oots filled for llicii- .i;iti,i;i\al half in accoi'dancc with the hcst Icchnic. 4. 'riic iiicisal oriliccs ol' the pulp chanihers are enlarged hy means of st<)n<>s siiitahlc in sliap<' and size. 5. Stai'lin.i;' willi the two ('us))ids, they will Ix' found to l)e more than l^.") mm. an cut sliow.s where the paiallelodiill shouhl bo oi!c■ turning;- tlie lock mit |)i'o\'i(leids 14-gauge wii'o (Bi'own & Sharp) would he used to he followed with a l.']-gauge drill. When tlie canals in the cuspids have boon ])aralleled, the SPLIXTIXC I.OOSI-; TKK'I-II WTI'll IXI.AVS '2'2\) cavities are cut into tlie teetli, liiiguo-distally, occupying a goodly portion of tli(» lingual surface and extended niesially so as to almost reach tlic labial surface. 'Ilic ])arall('l()iii('t('i- carrying two wire posts 13-gauge (Brown & Sliai'j)) clani])('d in tlieir respective grooves is now iitted into t1i<' ])arall('l canals. The instrument is removed from the moutli, and tlic distance between the posts is noted, recorded, and fixed hy hii-iiing the lock nut. Two friction angle trays, pro])ei'ly ]ul)ricated, are now mounted upon ])()sts and two ])latinum tubes are slipped over and onto the posts, the wall of these tubes is .007 mm. thick. The trays are moved up the wires until the incisal end of the tubes will disappear into the sleeves of the trays. Inlay wax is now melted upon the tray and around the tube, the outer wall of which luis been knurled by rolling it under a fine file. The wax is built up into the shape of a small pj^ramid upon both trays, and the instrument noAv carrying trays, Avax and tubes, is guided back into the root canal of the cuspid teeth, and forced into i)osition. The trays carrying the wax are now brought uj) so that the wax will be forced into the cavity. A stream of cold air is directed upon the cuspids, while the trays are held in this position, until the wax has stiffened beyond the possibility of change and form. The instrument is now removed from the mouth, and with a small, sharp lancet, the surj^lus of wax is cut or carved away. The clamps which hold the wires in the respective grooves upon the meter are opened, and the wires, which carry tray, wax and tubes are released. A pin vise, held in the right hand, grasps the tube, while the left hand carefully moves the tray downward u])on the wire, and finally the tube and wax inlay as one are remoA-ed from the wire. AVitli a lancet and proper carvers, the lingual portion of the wax inlay is now carved out into a retentively formed cavity, to be subsequently occupied by an inlay, which carrying a split pin, will engage the platinum tube, and which iiday and split pin, in conjunction with the one upon the opposite side, will l)e joined to the bridge to serve as attachments for it. A graphite post from which the oil lias been thoroughly burned out, and which is of the same caliber as the wire, which c\^ COIJ) AXD roiU'KLAlX IXl.AVS lilted into tlio platimiiii tiiho, is now inserted into the tube, a sprue wire is lieated and inserted into that portion of the Avax inhiy Avhieh is thickest, and farthest away from the phitinmn tuhe. The sprue wire is inserted in such an angle that the mol- ten gold, upon being forced into the mold, will not strike the tul)e as an ol)struction, in its travel, hut will raher have a chance to attach itself to it in an enveloping maner. Fig. 189. — Distance established between left cuspid and right central. Drills are the same distance apart. P'ig. 190. — Di.'^taiico estal)li.slicd l>otweoii right cuspid and left central Drills are the same distance apart. TIk' cavities in ;ill 11i<' aiilcfior teeth, which arc to he spliiili'd logellicr, iiiiisl lie cxli ii against the wax, thns forcing the same into every portion of the cavity not occupied by the wire. With the tray under ]n'essnre, a stream of cold water is directed upon the tooth, until the wax cones become fixed in that position, when the wire and the wax inlay and the tray may be removed. A¥ith a sharp lancet all the surplus wax is carefully trimmed away, the (lerman silver tray is removed from the wire, and the wax inlay and post are now replaced into the cavity, and with the proper carvers, and flat right and left burnishers, the wax is made to acquire its proper disto-linguo-mesial outline. The post and inlay are now carefully removed from the tooth, and the sprue wire is inserted as previously indicated in such a manner that when the mold is ready to receive the molten metal, the post shall not act as an obstruction to its (metal) free ingress into the cavity. In this manner, all the post-carrying iidays for the teeth involved are completed and j^laced into their resiDcctive cavities. If the teeth are very loose they must l)e supported in joroj^er ])osition Ijefore any attempt is made to take an impression of the inlays as assembled. This is best accomplished in the fol- lowing manner: AVitli a silk ligature the teeth are drawn into proj^er rela- tion to each other and firmly tied, the ligature must be placed as near to the incisal edge as possible, without exposing it to the 232 CAST COLD AXn PORCELAIN INLAYS likelihood of its slipping, a stick of De Tray's modeling com- ponnd may be softened and placed npon the labial snrface of the teeth, extending from the gingiva np to the incisal third, and reaching around to one-half of the distal surfaces of the cuspids, lield in this position, the modeling compound is chilled Avith a stream of cold water. A plaster impression may now be taken with the inlays and modeling compound in position, and when the plaster begins to set, a stream of cold air should be Filicii .spl'mt icaily t« 1)0 insoitod. Note the perfect alignment of the liosts. (Sketch made by Dr. Leo Stcru.) directed ii])<)ii tlic 1ra>- in oi-dci- to ])r('V('iit the heat, generated by the crystallization of the ])laster, from softening the com- y)0und or a bhist of cold aii" may ])v ])layed upon the ivixj. Wlien the ])lastei- has hafih'iied, the tray is removed, the lahial poi'tioii of the impression is lifted off, and usually the imj)rovised modeling c()mj)osition splint will come with it. The ligature is then removed from the tooth, and as a rule this will cause a loosening of the lingual portion of the impression, which Sl'LIXTIXc; J.OOSK 'I'KK'III Wnil IXI.AVS L'.).) iiuiy now ])e roiiiovod. Tf the inlays have remained in the teeth, eacli one is removed and phiced into its corresponding seat in the impression. W'lu'ii all of llic inlays ha\'(' hccn ass('in])l(Ml in the iinjjres- sion, they aic waxed into ])osition, eare bein<>,' taken not to let the wax iiin onto any of the margins, their tinal seenrity in posi- tion l)einf^- attained hy waxing- a piece of wooden toothpick onto l)()tli iin|)r('ssi<)n and ])()sl for each inlay, so that, if we liave six inlays in position in the im})ression, we shall have six posts rising in parallel i-elation to each other and onto each of these posts shall he waxed a piece of wooden tooth])iek, the other end of which, shall he waxed onto the impression. AVith a camel's liair hrnsh, the cavo-snrfaces of all the inlays are covered with graphite ]:)aste, the refractory compound is mixed to its proper consistency (that of a fairly thick j^aste) and with this paste the impression is filled, care 1)eing taken to apply a little of the paste at a time, using a brush or a small sj^atula to build the refractory compound into every portion of the impression, and around all parts of the inlays and posts, until a model of suffi- cient size has been secured. The refractory compound is allowed to harden sufficiently to prevent displacement of any of the parts during manipula- tion, coincident with the separation or cutting away of the im- pression. This cutting away process nmst be carefully done. AVe nmst bear in mind, that all our efforts are directed to leave the inlays in the same relative position upon the refractory model, which they occupy in the mouth. When the impression has l)een entirely removed from the model, the inlays situated in the model are carefully and thor- oughly cleansed, an examination is made to determine if they are in contact at the i^oints where they are to be joined to one another, and if they are not, they are brought into contact 1)y carefully fitting small jneces of clasp metal, or iridio-platinum into tliesi^ ])lac('s; the line of junction is carefully waxed up, while additional refractory compound is placed ujion all the exposed parts of the inlays. After this has hardened, the piece may be placed upon the fire for a few moments, when the wax may be removed, the piece may be replaced on the flame, allowed to heat up for another few minutes, Avhen it is fluxed, and small 234 CAST COIJ) AND I'OIU'KI.AIX IXl.ANS pieces of soldrr ])la('ed at the i)()iiits wIktc union is desired. Wlieii the piece has l)een thorougiily lieated by the flame tlic bloAvpii^o is applied and tlie inlays are soldered together. It is advisable to alloAv the j^iece to become fairly cool be- fore any attempt is made to take it out of the model. Wlien tlie l^roijer time comes, this may be done and the now joined inlays are removed from their place upon the model, thoroughly scrul)bed with soap and water and thrown into hydrofluoric acid to remain for a period of half an hour or so. They are removed from the hydrofluoric acid, thoroughly washed, and thrown into a bath of Avarm hydrochloric acid, again removed, thoroughly washed, and boiled in a sodium bicarbonate solution. A¥ith lit- tle stones held in the engine handj^iece, all excess is now ground away. Care nmst be taken not to encroach upon any margins during our finishing and polishing operation. If our patient is waiting for us to complete the entire opera- tion outlined above, no particular provision for the care of the teeth that are to be splinted need be made except the closing of the various cavities by means of temporary stopping. But if the patient is to be discharged and is to be absent for several days, pending the completion of the splint, some provision must be made to protect and support these loose teeth during that time. I have found a most efficient method of supporting these teeth in the following manner: The teeth containing the cavities ai"e thoroughly sprayed with wann water. Cotton rolls are a])plied and the teeth are dried with warm air. The saliva ejector is ])ut into the patient's mouth. Small pieces of tem])orary stoj)})ing ai'e softened and formed into cones. The cavities in the teeth are lubricated with eucalyptol compound and a ])iece of the soft cone-shaped stopping is put into each tooth. Staples of round Cerman silver wii-e of suita])le thickness, 18- and 2()-gauge, respectively, are now held in the (lame and when siifficiciitlx- licatctl ai'c allowed io eiiihed Iheinselves into first llic Icl'l cii-itid and lali'i'al, IIhmi IIic \r\'{ |;itei'al and lefl central, llien llie Icl'l (•<-n1ral and llie riglil cenli'al, llien llie rigid cenli'al and ri;;lil lateral and liiialK the I'liilit lalei-al and Sl'LIXTIXC J.OOSK TKK'I'll WITH I X LAYS 235 ]iglit cuspid. It will be noticed that all ))ut the two cusi)id teetli carry a double staple. Witli a heated ball burnisher of suLtal)le size the staples are ur^ed ' he dismissed and llic siudy of the models begun. Each ino('ntly take lip the woik of restoration. If the nearly ])erfect tooth is an upper one, then restora- tion should l)e<;in with the lower tooth, occluding' with the nearly ])ei'fect upi)er on;', and if the nearly jierfect tooth he a lower one, then the jjrocess is reversed and the u])])er teeth oecludinf;' with it are restored tirst. Each one of the teeth in the human mouth, except the two upi^er third molars, and the two lower central incisors, enter into occlusal relations with two opposing teeth, and broadl}^ speaking, three teeth, two uppers and one lower, may be considered as an illustration of a lever, one upper tooth representing the 2)ower arm, one the weight, and the lower tooth the fulcrum. As a matter of illustration, the reverse of this proposition holds good; that is, two lower teeth form, respec- tively, the power and weight arm, and the upper tooth the ful- crum. AVhen all parts entering this relation in trinity, are functioning ])hysiologically, we may consider occlusal balance as present. AVlien the teeth which enter into occlusal relation with the nearly perfect one have been restored, we shall have an occlusal guide to assist us in bringing about occlusal balance in the en- tire mouth. It will be best to cut the cavities in the teeth upon the models with small chisels, such as are used by sculptors or engravers. AVe shall try as nearly as possil)le to dui^licate the ideal line and margins and ])lanes upon tlu;' natural teeth, as we have cut them into the plaster. This is not nearly so hard as it would seem; in fact, it will prove much easier than most students would be ready to believe. The reason too, is cpiite simple and here explained: If we had omitted taking impressions for study models, and 240 CAST COLD AXP TOltCELAlX IXLAYS making our diagram of .stress, and omitted tlie outlining of the cavities ui)on tlie models, and of cutting these cavities iiito the models; if ^ve had omitted noting the most nearly perfect tooth, and Iiad attacked the case in liand witliout study, hajDliazardly, it is not only likely but quite ai)i)arent, that the very extent of the task would have bewildered most of us and our anxiety to bi-jng some oi'der out of chaos would have made us overlook the tine and most essential points in cavity preparation. All of this work of study of the models, and stress, the making of the diagram, the taking of the history, etc., has consumed hours, and made us familiar with the case. If we omit this, the case is strange to us, and we are strange to the case. The difficulty is added that we are dealing with live tissues, and Ave are nnde- cided just how extensively to cut; in other words, Ave do not know exactly what to do. But if we liave made the careful study, as outlined here, and if Ave have cut the caAdties into these teeth as our knowledge of stress conditions and innnunity areas, etc., t(dl us Ave must; and if Ave liaA^e j^lanned our restorations upon the models in accordance with the requirements of occlu- sion, and phonetics, and harmony and proportion, and l)eauty, then we know exactly Avhat Ave Avisli to do, and the patient pre- senting, Ave j)roceed to do just that thing. It is true, Ave may ix' liam])ereil and interfered with l)y con- ditions in the moutli wliicli do not exist on the models, but A\'e bear in mind our I'esult on the model, and Ave try to duplicate it in the teeth, removing the obstacle as it presents itself. In this way, the i-csull of our woi'k- is more nearly likely to approach our ideal of our task-. It is (|nil(' a dinVrcnt mattei' to cut into live tooth struc- ture than i1 is 1o cut into models, and often the ideal is A^ery difficiiH 1o cjiii-y out, hut that is only anotlici- reason that the operator shonhl a|)])roach the ])ati('nt oni\' after a coni])lete and exhaustive study of the case, and with a thorough knowl- edge as to Avhat he wishes to do to each particular and individ- ual tooth, remembering alwa.vs that the ultimate to l)e desii'cd is hai'inonv and balaiKM' in the i-( Intioii oT the tissnes |)i-eseiit in tlu' oial ea\ity. If no ])ain oi" put I'eseeiit eondition be picsent to wv'j;^ the ojxM-alor's attention and sei'viee to any i)ai-tieular tooth, it is lox'iM'iXSix'i': i;i';s'r(ii!A'ii().\s oi' occu'sai. uai.axck 1^41 Ix'st to y this T mean that they are usually thirty-five to fifty-five years old when tliey seek relief. These cases ai'c so (^\tensi\-e, and the treatment so iiiv()l\-ed, and so much depends upon a favora))le prognosis, that no amount of care gixcn to tliese i-estorations can be said to be too nmeji. T\\(' ti-eatmeiit is, with the gi'oatest caic, (juite a sti'ain U])Oii the ])atieiit's uerN'ous system, and lor this reason, if I'oi" no otliei-, the ])atient should he dire('1e<| to consult a cai-efnl internist, a diagnostician of the liist rank', and a i-e|)oi't should be obtained from him as to tiie genei'al condition of the j)atieiit. KX'I'KXSINl'; IMvSTOilA'l'lOXS Ol' OCCl.rSAI. IJAI.AXCE 243 '^I'o a lar.nc cxlciit the |)i-(),i;i-('ss oF tlic dciit.-il work will de- pend u))()ii tlic i-('|)()i-t liaiidcMl ill ))y the |)liysi('iaii. IT llio ^■en- eral condition of the paticiil is such that lie can witiislaiid Hie stress of prol I'actcd denial operations, a Ni^oi-ons pi-o,i;rani may ])e pni'sued and the woiU linishiMl in a inm-h shoi'tei- time than if the re|)ort ahout his ^I'nei-al condition were to noetssitate careful ft'uardin^- a^i^'ainst the least shock to the nervous system. It is wise to always ))ear in mind that these patients liave, by virtue of tlie very condition winch ))rinf>,s tliem to us, received an im|)ulse which started them ■ for al least KX'I'MXSIN'I'; IMOS'l'OIIA'l'lOXS (»l' OCCLI'SAI. I'.ALAXCE '24^) llircc (lays, 'riiis iimsl he insisted upon, and in (jrdcr to help the j)atieid onci' his 1i-yin,i;' time, lie must he k(=j)t vci'V l)iisy (lui-in,i;- tlu' da>\ must lia\-e sleep a1 ni,i;ld, e\-en if tlie sleej) is to be indiiccMl hy liyjjuot ics. If tlie lath |- ai'e employe(|, tliev are followed by tlie use of laxatixcs. After three days the ])atieid is allowed to remove the sjjlint durini;- meal time. The strictest liy<;ienic ])reeautioiis are employed in kee])in,^- the mouth clean, and no deviation from the prescribed regime is ])ermitted. It must be ivniemhered that this is a i'e-creati\-e \\()i-k that is g'oini;' on, and that the operator is, if he has the necessary intelligence, in truth a creator of a real ])i-iniary factor in the human economy. The i)atient must be made to realize this for his or her own ultimate good. Xever l)efore, in the liistory of human error, has it been I^ossible to so utterly wipe out every evidence of this dental shortcoming as it is today. It is very likely that even the minds that conceived this entire process of cast gold inlays, never fully realized the extent of the blessings tlie process might bring and but for this process our work in these cases would l)e today as it has l)een in the ])ast — nothing l)ut a ])0()r i)a.lliative effort, full of nothing so nmch as futility. CONSTRUCTION OF THE SPLINT Plaster iin])r( ssions are obtained from the ui)per and lower jaw, and models are made. Three layers of number .001 tin foil are burnished over the upper model, taking in the crowns of the posterior te( th and extending u]) to the gingi^•al surface of them and beyond, and as far back toward Hie ])alate as a i)late made for the case would be allowed to go. All of the i)alatal surface of the foil, as well as the p)art covering half of the ])alatal surfaces of the teeth, is covered with a sheet of basejilate wax of medium thickness. The balance of the palatine surfaces of the teeth and the occlusal surface upon the four posterior teeth is covered with three or four layers of the same base])late wax and the buccal surface of the Toil upon the posterior teeth is coated with one 246 CAST (lOIJ) AXL) roiICELAIX IXJAYS layer of llic A\ax, wliidi lixyev is to reach over and onto, and be melted into, llie three or J'onr layers of the occlusal waxes. Tliis wax must he niari;iually melted onto the foil, so that A\lieii the foi-mer is removed from the model, the foil will come with it. The wax is trimmed to jn'oper outline, and a suri)lus of foil is allowed to remain, wliich may be folded back on the Avax. This contrivance is chilled in ice water, and placed in the pa- tient's mouth for determination as to occlusal thickness. It is removed and replaced upon the model, a layer of soft wax is ])hice(l upon the occlusal surface and melted onto it, so that we sliall have a layer of wax ujjon tliat surface about one-half inch thick. The jDlate is again inserted into the mouth, and the patient is admonished to swallow and close the teeth. The re- sulting- impression of the loAver teeth on the wax will furnish the necessary guitle to place the lower model into projjer l^osition. This is done, and two jjieces of wood, reaching across from model to model, are waxed onto each model, and the};^ are placed in the anatomic articulator. AVhen the plaster has set, the ad- justment screw is fixed, the surplus of the plaster is trinuned off, the two pieces of wood are removed, the articulator opened, and tiie wax and tin foil are carefully removed and laid aside. A careful preliminary study of the models should now take ])lac('; undercuts which may interfere Avith the placing of the sjjlint should be filled up, or otherwise obliterated. The lower model is covered with a layer of tin foil, the ai-ticulator is closeAX('K -!.)1 responding' Uj)j)('i" section, are reinoN'ed fi-oiii tlie investnienl conipoiind, iinislied, and 2)olislied and ])la('ed into the mouth; the i^atient is diiccled to close the nioutli, and it will he found that the naso-mciital line is now 2% inches lon,i;- instead of 2'/{. inches. Of late I have joined these ])lates 1)>- \ulcani'/jn^' ruhhei' between and onto them, in which case the occlusal surfaces of these plates nuist he c()nsi(leral)ly roughened, so that the ruh- ber will adhere. The parts of one ])artial splint which covers the tirst upper and lower molars and the second bicuspids are cut out with a bui-r and saw; this will leave one partial splint tittiuft- over the last molars and hrst Incuspid. We are now in a position to begin the reconstruction of the first molars and the second bicuspids. If the teeth are still in normal mesio-distal relation, then the amount of building up to be done is easilj^ determined, if we consider the following: From the gingival line up toward the occlusal surface, a tooth may be divided into three parts horizontally, which will give a gingival third, a middle third, and an occlusal third. The mesio-distal relation of posterior teeth takes place at the greatest circumference of these teeth, and the greatest cir- cumference of these teeth is invariably to be found at the gin- gival i^lane of the occlusal third. The teeth of the case in hand, being in mesio-distal relation, we conclude that only the occlusal third or less has been de- stroyed ])y attrition. We measure the remaining portion of the teeth, gingivo-occlusally, divide the result in half, and we know how high the tooth should be when restored; this is, of course, to be done before any cavity j^reparation is attempted. If the mesio-distal relation of the teeth has been lost be- cause of this process of attrition or otherwise, the following rules will have to be l)orne in mind when we are engaged in the correct restoration of these teeth. If every surface of a molar, except the occlusal surface, be ground at right angles to the gingival ])lane of the gingival third, in otliei- words, if taking the circumference of the gin- ival plane of the gingival third as a guide, we ground the 252 CAST COLD AX I) PORCELAIN INLAYS Fig. 196. Fkr. 197. Fio-. 19S. Fig. 199. EXTKXSIVH KICSTOKATIOXS OK ()('( '1,1 'SA F. IJALAXCE 253 Fij;'. 196. — All occlu^iil \\v\y (if tlic ukmIcIs of tlio same caso, the teriil)le liavuc wiouolit by iiogicct, niisiiiKlcMstaiidinf;-, aii- the direct line dropped from the occlusal eminence to the <;in.i;ival circund'ei-ence as illustrated (1-8, Fig. 203) on the chart. This holds good for the contouring of the four surfaces of the tooth, in the case of these restorations, the surfaces heiug pi-actically intact with the exception of ])ortions of proximal areas. The following geometric di-awing will aid in determin- UrtctK rou^ K cunXfc of pup Orbito-Uasal Una, 1 7s vucKeS,- -' y^^--- /B iucKeS lower Up Uppev Up ^4it\cKt5 -V-V--< TlaSo-HUnial lme2)iiivcluk 2 tuike^', ! Fig. 202. ing definitely the extent of the mesio-distal restoration re- quired to obtain a normal contact area between the teeth mesio- distally. The figures enclosed by the letters BCEF and KHOP (Fig. 203) show two central cubes of two adjoining teeth, as they would rise minus any contour from the gingival j^lane of the gingival tlnrd of the tooth. In adding the proper contour mesio-distally, the mesio-proximal triangle ELF of the pos- terior tooth, dips or extends into the disto-proximal triangle 256 CAST GOLD AXP rORCEI.AlX IXLAYS bo I'A'i'i-: xsixi'. i;i;s'i'(»i:.\'i'io\s oi' occi.rsAi, i!.\i,.\.\('i': 'J.)( It must ]h' Inline ill miiul that tliis fliart rcprcsfiit.s a tootli gooiiietric-ally. It is, tliorofoio, coiivfMitioiializpd. A variation prosonts itself in the location of the linlit anj^los, as follows: In Ujipoi- niolais the rii;lit anisic jircscnts at tlio giiij;ival piano of the occlusal tliinl luiccallv, and the j4inoi\al plane of the midille third palatal ly. In lower molars the ri^ht anj;le presents at the oinoixal |>l;ine of the middle third huccallv, and at the ninqival plane of the occlusal thiid linjiually. Furthermore, if we lay out the respective right an^lrs of the upper and lower molars and continue the bases and altitudes until they intersect, we will produce squares with sufficient variations in their lines of direction to account for, and to coincide with, the rhomhoidal and trapezoidal figiire.5 of the gin^ival jdanes of the gingival thirds of the respective teeth. Fig. 1. — ^lolar crown divided horizontally into thirds. J A. Occlusal third. BB. Middle third. CC. Gingival third. Fig. 2. — Same, with thirds separated. AJ. Gingival plane of occlusal third. BB. Occlusal plane of middle third. CC. Gingival plane of middle thiid. BD. Occlusal plane of gingival third. £7?. Gingival plane of gingival third. Fig. .'!. — Gcometiic construction of contours of molars. A line drawn from highest eminence of cusp, to a point on the circumference of the tooth at its neck (XY) , becomes the Iiypothe- iiuse of a right-angled triangle (XYZ), the right angle of which will lie opposite the gingival plane of the occlusal third. XTZ. the right-angled triangle. XY, the hypothenuse. XZ, base of triangle. XY, altitude of triangle. Fig. 4. — Geometric solid figure, properly triangulated, from which molar crown may be carved. Fig. 5. — Same Avith component sections separated. A. Cen- tral rectangidar pillar. B. Mesial wedge-shap)ed section. C. Lin- gual wedge. D. Distal wedge. E. Buccal wedge. F. Mesio-buccal angle section. Triangular pyramid inverted. G. Mesio-lingual pyramid. H. Distodingual pyramid. /. Distodniccal pyramid. Fig. 6. — Geometric figure, showing second stage of carving molar crown, the cusps appearing as quadrangular pyramids. Fig. 7. — Third .stage. One half of crown carved out. Fig. 8. — Crown completed. 258 CAST GOLD AXD POrtCELAIN INLAYS KM II oi' the anterior tootJi, in siicli a manner tliat a quadri- lateral iigure IMJL is formed. If a perpendicular line TIG is drojiped between the two teeth, it will bisect this quadrihiteral figure, and will also be tangent to the two arcs UV and ST both arcs being parts of two circles the centers of which lie externally to the two teeth involved. In the former chart of geometric tooth construction within the two triangles XYZ is seen a dotted line indicatmg the api)roximal contour of a molar tooth, and by stud^dng the two charts, the student will know how to determine the extent to Fig. 204.— The figures cudoserl hj the letters BCEF and KNOF show two cen- tral tubes of two adjoining teeth as they should appear when dressed down to receive crowns. The mesio-proxinial triangle ELF of the posterior tooth, dips, or extends into tlie disto-proximal triangle KMN of the anterior teeth in such a manner that a quadrilateral figure IMJL is formed. If a perpendicular line EG is dropped betwo::'n the two crowns, it will bisect this quadrilateral figure and will also be tangent to the two arcs VV and ST, both arcs being parts of two circles, the centers of which lie externally to the two teeth involved. which his ajJijroximal eoiitoui- line should lie within tiiat tri- angle at the point of a])proximal contact. AVhen with a view to all factors involved (diagrams of stress and contour), immunity and re-creation of balance, the cavities in the first molars and second bicusj^ids have been pre- pared, and the inlays completed and cemented into place, all of which was done while the partial s])lint remainecl in jjosiiion EXTENSIVE llESTOltATIOXS OT OCCLrSAI. UAI^AXCE 259 Fig. 205. Fig. 1 is a horizontal section representing the occlusal plane of the middle third of an uj)per second bicuspid. The heavy curA-ed lines within the circle repre- sent the mesial and distal surfaces, while the dotted curved lines indicate the form and proportionate height of the buccal and lingual cusps. ABC is an isosceles triangle which has the line JB as the base, and the lines AC and CB the respective sides. The angle ACB is tlie apical angle, and being bisected by the line CD, this same line will also bisect the lingual cusp of tlie upper second bicuspid. Fig. 2 is a horizontal secition representing the occlusal plane of the middle third of a lower second bicuspid. The heavy curved lines within the circle represent the mesial and distal surfaces, while the dotted curved lines represent approximately tlie buccal and two lingual cusps. EGF is an isosceles triangle, with the line EF as the base, and the lines EG and FG as the respective sides. The angle EGF is the apical angle, and being bisected by the line GH, the same line will also bisect the buccal cusp of the lower second bicuspid. 2(i0 CAST COIJ) AND I'()|;ci;LA1 X l.\l,A\'S on the ()])j)()sit(' side of the iiioiitli, sup|)l \ iiii;' tlic cU'liiiitt' ]iLMi!,lit to ^v]li('ll tlu' Iceth heiiiii,' restored were to ho raised, that part of the rul)))er spliid Jittiiig over and around the ]-estored area is eased so that it Jiia\- i:,o to place and rest npon the teetli not yet rehuilt. All additional section ol' the pai'tial s])lint, l)elon1ei| to niak'e it conronn to the new conditions hy i'enio\iii,i;- ,-ill ol' llie orclnsnl snrl'ace of il on that h Is then plac«(| in 1 he oral ca\ Il>' and 1 he space pi'e\Ionsly occnj)ied hy the ent end section is lill(M| willi a roll of ncIIow wax, the palicnt is direelfd 1o close llie nionlli nnlil the teeth ()]\ the other >ide are in oeehisal I'elalion willi the s|)linl. .V EXTKN'SIVK r.KS'roilATloXS OF OCCIJSAl. I'.ALAXCE '_>(;i few mimitcs arc allowc*! for the wax to harden, 'riic <\)\'\\\i JS removed, (lasked, cleaned, packed, vulcanized, and ])()lislied. It is I'etunii d to llie palieid at the next sittin;^-, wlien the ])r()ce(lure '»r I'csloralion i> a-ain slailed witli tlie lii^t mohirs and second bicuspids of the opposite side. At this point we iiia\- dispense alto;j,<'tliei- witli the i-einain- iuf;- ])artial s|)lint, the opposite side ^ivin,:;- a icliahle occlusal <;uide. 'I'hus we -o to the second niolai's and thifd, if any he pi'es- eiit, and linally to the first l)icus])ids, easing the iiihber splint froin time to time until tlie first bicuspids have been ruily re- stored, when the lubber s])lint may also be dispensed with. We shall lind now that the naso-mental line has increased in length, that the jjosterior teeth are in normal mesio-ilistal relation, and that we have re-created an occlusal balance of the ])osterior ])art of the masticatinft- apparatus which will leave nothing- to be de- sired, and the perfection of which we never could have e\-en a])- ])roached without the help of the casting- process. The followin-;' is a quotation from an editorial written for the JJcntdl Items of Iittrrrst, .May, 1913, by Dr. Ottoleni-ui, an editorial which has the distinction of bein<;' timely and true. "In the past we have contoured teeth, but we have not con- toured them to the extent implied by the word 'restore.' "The contourists have replaced corners, have built u]) in- cisal M^^i^>< with fair accuracy, and tliey have even rounded out the approximal or circumferential sha])es of teeth. But tlicy have irorfiiJIii failed to even fairly ivdl imitate the oeclusal surfaces of bieuspids and molars. "Perhaps never until now has the dental world been fully aroused as to the iin])()rtance of restoring occlusion. The or- thodontist and the prosthodontist have far outstri])ped the den- ists in this ]-es])ect, but the time has now arrived when tiie ilen- tist must awaken and grasp the need of making occlusion the fundamental princii)le of everyday work. "Any child would tell us 'teeth are made to eat witli.' The great Master so formed these oigans tliat they would not only 'eat,' but 'eat' well. The slightest loss of any ])art of the masticating surface of a tooth, the most minute change in its designed roiiii, diminishes its usefulness as a masticatory or- 262 CAST GOLD AXD PDIlL'ELAlX i:s'LAYS .Fig. 207. Fig. 208. EXTENSIVE ItESTOKATlUXS OF OCCLL'SAL IJALAXCE 203 Fiff. 209. Fig-s. 207, 208, and 209.— Three illustrations of lieautit'ul oc- clusal surfaces. Two lower models above, and one upper model lielow. Xote carefully the second lower bicuspids and second upper bicuspid. Note also the continuity of the disto-buccal cusp of the first upper molar with the mesio-lingual cusp. (Dr. J. Lowe Youiic'.) 204 CAST GOLD AND POllCELAIX INLAYS g'an to just tliat extent, lieversely, wlicre ])art or all of the occlusal surface of a tooth is lost tlir()U,i;h caries, the more nearly tlie dentist succeeds in restoiiii.i;' its original form, the more perfect does he make the ])atieut's al)ility to masticate food. "Hundreds of articles have l)een wi-itteu u])on the need of restoring ai)proximal contact as a ])rotection to the gingiva Fig. 210. — Xote the two illu.stratioiis on the lower portion to the left, with their inefficient occlusal surfaces, and compare the four other illustrations with their definite .sulci, cusps, and fissures. which iiOi-iiiall>' fills the iii1<'r])roxiiiial space; hut a close study of the anatomy of tlie i"(-gioii will deiiioiislrale that the con- tact of adjacent teelli is only one ol' .Vatiiic's measures foi' the jii'otection of tlie gingiva, and not the most important. At the approximal margin of tlie occlusal siiifatM' of molar or hi- cus])i most slanting plane extending ar()iiiid the center of that sniTaee, and there- FA'TEXSIVE r.ESTOUATIOXS OF OCCIA'SAL BALAXCK I'd.-) Fig. 211. — Tins illiistratidii anil Fi-. I'll' arc sliowii to call to Tuiiid tlio M'ays in Avliich attrition manifests itself in (liff"(Mviit tvprs. Note in this ilhistration a groat amount of attrition, and vet very well-dofinod and rather deep ocidu.sal ploncs. Note, also, to tlic rif>lit a iiial}n)sitiou of the bicus- pids and a consequent narrowing of the arch. This may be called a thyro-adrenal tooth. It is the tootli of tlie dreamei', the poet, and highly artistic architect, the landscape gardener, tlie artist, more so tlie impressionist, jiooplc of culture, and us- nally ]ieople of great sincerity. Fig. 212. — Another type of the result of attrition. The cusps and i^lanes are not so deep, not so well defined and the arch is wider. It is the pituito-guuado- adrenal type. It belongs to the imlividual who lives in conformity to form, — works <>ight hours, sleeps eight hours, and plays eight hours, etc. He makes no laws, they are made for liim. He docs not dream or speculate, dees not philosophize. He votes with the mass. lie is not the creative type. 2GG CAST GULL) AXD POllCELAl^; JXLAYS Fia-. 213. :i4. riff. 215. A Case of Extensive Eestoration. Fi{^. 213. — Tlic models of tlic case after inlays wore inserted. As Jiiay Le seen, tlii.s case presents consideralde nial])0.>ition of a number of teeth. Note the occlusal surfaces, the distinct cusjts, sulci, niai^^iiial ridges, and the essential hell shape of tlie teeth as a whole. Fig. 214. — Anterior view of models in (icrdusion. Note the (ivciliite, the ten- dency to tortion of the right lateral. Fi":. 21.J. — A side view of he sanu; mcMleis in orclnsidii. EXTENSIVE ItESTOr.ATlOXS OF OCCLVSAl. IJALAXCE 267 Fi-. 216. Fig. 217. Fig. 218. A Case of Extensive Kestoratiox — Coxt'd. Fig. 216. — A lingiial viow of the niodcl.s in oecliisiuii. Note the correct inter- digitation of the cusjis. Figs. 217 aud 218. — Views of the same models in occlusion^ but cut in half to show tiie inlays more clearly in outline and occlusion. '2GS CAST GOLD AXD rORCELAlX JXLAYS fore away from the ai)i)roxinial sijace. Tliese marghial ridges lead down into gntters, wliicli in turn carry the escaping food lingually and l)nccally. so tliat in the normal state the contact l)oints need 1)e hnl small rounded areas, as tliey are, to prevent food from crowding (k)wn against the sensitive and easily in- jured gingiva. Thus the absolute copying of Nature in the restoration of occlusal surfaces of molars and hicusjoids not only increases the masticatory efficiency by supplying cusj)s and fossa\ hut protects the soft parts and j^reserves them in a state of health because of the marginal ridges and sulci." SUMMARY FOR CHAPTER XVIII Extensive Restorations of Occlusal Balance by Means of Gold Inlays 1. Xanio the two causes of the mutilation of tlic occlusal and proximal surfaces. 2. A\'liat are tlie ijielimiuaiy steps beftjre Ijeyinniug a ease of extensive restoration? 3. Explain tlie method of making a diagram of stress from the model. 4. Explain the reasons for the choice of the first tooth to be ojierated ui)Oii. 5. "What are the causes of attrition? Name a predisposing cause. Name a secondary cause. f). Describe the oral conditions in a case of marked attrition. 7. How would you determine the amount of gingivo-occlusal restoration to be made? 8. "What steps should first be taken in the actual process of Avork upon the patient? Construction of the Splint 1. Describe the making of the spliiit, giving the various steps on the model and in the mouth. 2. How would you determine the am.ount of opening of the articuuitur tlic case requires? 3. What is the reason for doubling the amount of the necessary gingivo- occlusal restoration? 4. What is the naso-mental line and liow is it taken into consideration while making the restoration? i). Describe the construction of :i initial splint. G. With the teeth in ncjrmal mesio-ilisf al j-ehition, how is llic aiiKtiiiit of building up dcterniincfl? 7. Descrilie tiic ciiangcs in tlic I'lill sjilint wliilc tlic lunccss of iccoiist iiictiou proceeds. (MIAPTKIJ XIX <;()ij) lXLA^'s AND rwi: siucA^rKS on i^ouckj.aix For eosiiictic fcasoiis, too well l'tliy eoiKsiclerntion, the cast o-old inlay is in itself C'ontraindieate(l ill anterior teeth and even tirst l)ieusj)ids, in sncli ])ositions as will ex|)ose aii_\' eoiisiderable i)()i'tioii ol' tlie ,i;old to tlie vision of the person with whom tlie patient eoiiies in eontaet. Yet in a <;reat many eases of broken or worn down an- terior teetli, the east ft'old inlay is, from all ])oints of view hut the one mentioiie(l, the very l)est restoration possible; in faet, it it were not for this cosmetic ol)jection, the east ft'old inhiy would i^rove the ideal restoration for large areas in anterior teeth, and it must I'ohow that if this one objection can be over- come, we shall, in the cast gold inlay have as j^erfect a re- creative process for anterior teeth as it has proved itself to l)e for posterior teeth. This conclusion led me to a series of tests and experiments which were not restricted to my own j^ractice at all, but were no doubt carried on by a great minil)er of men who realized the advantage of the casting process and were desirons of over- coming the obstacles to its use in the anterior teeth. Excejjt to a vei-y limited extent, I have no means of de- termining just hoAv extensive these experiments of the other men have been, or how successful they have proved, but I am in a position to state that in my own jn'actice, the cosmetic ob- jection to the cast gold inlay in anterior teeth has been entirely overcome by the use of porcelain, or the silicates in conjunction with the inlay. Broadly speaking, all but the part exj^osed to view is re- l)laced with a gold inlay, and a portion of the gold inlay is so sha])ed that, with the remaining part of the tooth, it will offer the means of the construction of a simple cavity, which may be inla^'^ed with porcelain or filled with a good silicate cement. In cases of marked attrition, where the crowns of anterior 209 270 CAST GOLD AXD TORCELAIX INLAYS Fijr. 219. Fio-. 220. Q Fi- 22L Fi- 21 Fiff. 222. Fig. 224. Fitr. 22.J. GOLD INLAYS AXD THE SILICATES OK POIICELAIX liTl Gold Inlays and Porcelain or the Rilicates. A Number of Views of a Lower Central Fk vctured in a Fall. Fig-. 219. — Liiioual view of cavitv. Fig. 220. — La])ial view of cavity. Fig. 221. — Wax inlay before providing room for porcelain. Fig. 222. — Wax inlay in jiosition carved out to make pro- vision for porcelain or silicate. Fig. 223. — Wax inlay ready to be mounted on sprue wire for investment in refractory compound. Fig. 224. — Labial view of completed operation. Fig. 22.5. — Lingual view of completed operation. Stress Index: Downward, inward and forward, or Intra- alveolar linguomesiaUy. . I'ASr COLli AND l'()Ii('l-:LAI X I X I .A \ Fiir. :2U(i. Fio-. 227. □ Fi-. 22S. Fill. 22!). Ki"'. 2:!!). i'l-. 2:; I. l-'\'^. 2:;2. COLD l.\•|,.\^S AMI 'I'lll': SIIJCATKS Oi; I'OlM'Ki.AlX A Xtmber of Views of a Lower Lateral Restored i;y ^[kaxs of a Cast Gold Ixi.av axd Ryxthetic Porcelain'. Fi-)'. '2'2i). — Lnliio-distal \i('w of |no])ai('(l tootli. Xoto l)Ovo]s at incisal, distal, and gingival margins. Fig. 1*27. — Ling'uo-iiieiso-distal view of proparea tootli. Xotc appearance of cavo-surface and the t-oiitinuity of linguo-niesial and linguo-gingival bevel. Figs. 228 and 220. — Lingual and cavo-surface view of wax iiday. Fig". 230. — AVa.x iiday in position on tlie tooth, jnovision made for porcelain or synthetic inlay. Figs. 231 and 232. — Lingno-inciso-distal and labio-distul views of the finished operation. Stress Index: Downward, inward and forward, or TxTKA- ALVKor.Aij lUiriun-Dx fiUilhi. 274 CAST GOLD AXn roiU'KLAlX IXLAYS Fio-. 233. Ficr. 234. Fiff. 235. Fis. 236. Fii Fi-. 238. Fi-. 23!t. COLT) IXLAYS AND THE SILICATES OR TORCHLAIX _(•) A Number of Views of a Lower Lateral Involved by Fracture and Decay Bestored by the Use of a Gold Ixlay ix COXJUXCTIOX WITH SILICATE CeMEXT, EOOT FILLED. Fig-. 2.''>.3. — Laliial view of ■ineparoil c-avity. Fig. 234. — Lingual view of i3iepare' he staiiii.^<' (l''«!i:!S Upper lateral incisors 11 " Bicuspids single root 1-i " Lo^Yer central and latcrnl incisors Ki " Low^T cuspids 1 •'> " Lower bicuspids 1-i " All these ])osts may he kept on hand under sejKirate eovei'S in two-iueh h'ii,i;-tlis. The re('ei)taele may he marked on the out- side so as to indicate the contents. The following simple rules mnst l)e rememl)ered in con- nection with the nse of posts: 1. The ijost is to aid in making the artificial restoration and the remaining portion of the tooth heing restored, one con- tinnous memljer, the cement being the intermediary agent. 2. The longer and stouter the post (within the limit) the greater the area of contact surface and the greater the resist- ance to stress. o. The length of the post should he at least % the length of the root. Additional contact s\irface is ol)tained hy threading the post. In accordance witli all the laws of cavity preparation, and in accordance with the diagram of stress, the cavities are then prepared and the wax inlays are made, which wax inlays mnst engage the post. This is accomplished in the following manner: A cone of inlay wax softened as i)reviously directed, is forced into the cavity and chilled uiidei- pressure; with the ])roper carvers the wax is then trimmed to size and contoui', the right, left, and straight ])nrnishers assisting in the opera- tion. A hole is then made in the contoured wax inlay lingnally, this hole going right through the wax and leading into the root canal. The hole slionld he somewhat smaller in size than the threaded ])ost. The latter is grasped in a pair of iDliers, slightly heated in tiie Ihuiie ol' the alcohol lamp or Bunseii hnrner, and I'orced into the hole in the wax iiday, and put into 278 CAST GOLD AXD POKCELAIX INLAYS Fio-. 240. Fi?. 241. Fijr. 242. Fio-. 243. Fiff. 244. Fi-'. 245 Fiii. 24G. OOLI) IXLAYS AXn TIIE SILICATES OR TORCELAIX 27'J A Numbi':r of Views of a Lower Lateral Fractured ix a Fall. Extirpated Pulp. Fig. 240. — Laliial view of cavity. Xote lievel and step. Fig. 24L — Liiigiial view of cavity. Note "jovel and lingual lock step with depression into pulp canal. Fig. 242. — View of wax inlay before providing room for por- celain. Fig. 24.3. — Wax inlay carved out to provide for jiorcelain. Fig. 244. — AVax inlay ready to be mounted upon sprue wire for investment. Fig. 24.3. — Mesio-lal)ial view of finished operation. Fig. 246. — Mesio-lingual view of finished operation. Stress Index: Downward, inward and forward, or Intra- alveolar Unguo-mcsially. 280 CAST GOLD .VXD rORCKT^AlX IXLAYS Fiff. 24; Fio-. 248. Fitr. 249. Fijr. 250. Fiff. 2.:i. Fi-. 2:> Fiy. 25:i. COLD INLAYS AND TllH SILK'ATKS Ol! I'OIICLLAIX 281 8EVEX VlKWS OF A LOWER CL'SPID, PrESEXTIXG ANOTHER Type op Eestoratiox. also a Combixatiox Cast Gold Ixlay AXD Porcelain Ixsert. Stress Index: Downward, inward, forward, liack and out- ward or IxTRAALVEOLAR linguo-mcsiolJ ij and disto-UihinUij. 282 CAST GOLD A>:i) roltCEF.AlX INLAYS □ Fio-. 254. Fig. 255. Fig. 25f). Fig. 257. Fig. 255 Fig. 2.59. Fig. 200. IIOI.I) l.XLAVS A.\l» TliE SILICATES (M! i'OlH'KI.AlX Seven Views of a P.koke.\-down Cuspid Ekstoked with a Cast Gold Inlay axd a Pokcelaix Insert. The Illustrations ARE Self-explanatory. Stress Index: DdWinvaiil, inward, forward, liafk and out- ward or Intkaalyeolak liiiritiu-ntr.sialli/ and (listo-hihialli/. 284 CAST COLD AXD POKCELAIX INLAYS Fig-. 2(31. Fio-. 262. Fitr. 26:5. Fio-. 264. Fig. 265. Fig. 2(iii. Fi- 2()|:('KLA1X lis.") A Left Upper Lateral Presextixg a Mesio-Labio-Lixguo- Incisal Deficiency Restored to Use and Cosmetic Acceptable- NESS BY a Cast Gold Inlay and Synthetic Porcelain. Fig. 26L — A lucsio-laljial view of prepared cavity. Fig. 262.— A linguo-mesial view of prepared cavity. Fig. 263. — Wax inlay in position on the tooth, provision made for synthetic insert. Fig. 264. — Lingual view of wax inlaj'. Note extension to tlio right. Fig. 26.5. — Cavo-surfacc view of wax inlay. Note definition of steps. Figs. 266 and 267. — Mesio-labial and linguo-mesio-ineisal views of finished operation. Stress Index: Upward, outward and liackward or iniraalvco- lar Labio-Distally. 28G CAST COIJ) AND Por.CELAlX IXLAVS tlio root canal. Tlu' \\ax iiiiiii(MliaU'l>- surroiiiidiiii;' tlic post ^^•ill soften siifficiciilly to atlacli itself to tlic threads upon it, and after a cold water s])ra\-, post and inlay may be removed. ]f there T)o any deticiency to tlie wax lin.nually, the (iiiaiitity lack- ing- may l)e added to it. fiday and post are ag'ain replaced in and onto tlie tootli, the cai'vini;' and l)nrnisliing" completed, re- niembering that all burnishing nmst be done in the direction of the margins; the Avax is rendered smooth with the cotton ])(dlet moistened sparingly with oil of cajej^nt, the inlay is carefully but firmly held in joosition, and with a small lance the facial i^art, and some of the mesial and distal surfaces of it are removed, leaving a box-like simple cavity, presenting a floor and four walls, the gingival wall l)eing formed by the in- cisal surface of the tooth. The wax inlay is now carefully re- moved, and the sjorue wire is inserted mesio- or disto-incisally. Tlie sprue Avire is placed in j)Osition upon the crucible former and all steps necessary for proi:>er investment and drying out of the mold, the cooling down of the same, and the casting of the molten metal into this mold are gone through as descri))ed before. T'l^on completion of the casting, it nmst be subjected to its various cleansing and neutralizing baths, carefully finished and polished with the various stones and discs. If we are to replace the facial portions with a silicate, then the boxlike aperture is so grooved that a retentive form is obtained; this is easily accomplished by running a small inverted cone burr along the incisal, mesial, and distal line of the floor of the cavity in the inlay. Jf we are to replace the facial ])oi-tions with a poi'celain inlay, then the boxlike aj)erture in the cast gold inlay must be left in such a condition that no undeiruts are present, so as to facilitate the taldng of an ini]ii-ession of the facial snrlace of tlie tootli and iiihiN' ca\"ily when the go hi in Lay has been cemeide(l to ])lace. AVIkmi the gohl iidaN" has heen eompleteil, the fnbbei' dam is applieil jiiid the casting is cemented to ])lace. The cemeid is mixed )-atlier thin bnt well spatulated and some of it is ])um))e(l U]) into the canal by means of a .jilT.N' tuhe wln'n the casting- has been foj-ced iido ])Osi1ion by the lingers, it i:< tapped geidly col. I) l.N'LAYS AND TIIK SIIJCATKS Oi; I'OIU'Kl.A I \ 287 willi a leal 1i('1'-('()\-('1'(m| inallcl, d |-i\iii,L;- a (liill-|)()iii1('(l iiisl I'liiiiciit licid against llic lingual siiiTacc in a lofwai'd and upwai'd direc- tion. AVlien the ('('inciil l)c,i;iiis lo set, llic poi'lioii wliicli lias 1)0011 forced inlo llic facial hoxlikc a])('itun', is removed with an oxcavatoi', llic inlay hein^' Indd liinily In ])()sition until the cement has tliorou.L^lily set. Tlic cimplc ca\ily now ])resontinft- npon the facial surface of tju; ])artly restored tootli may he temporarily tilled \vitli tlioiou^hly softened white temporary sto])])!!!^'. Xo ])ressnre shall he exercised npon this stoppin^j,-, its function l)eiii;lavs and tjiI': siiJCAri:.s on poucelaix 289 Views of a Right Upper Central PRfTsENTixG a Large Mesio-Labio-Linguo-Iincisal Deficiency, Restored to Use and CosjiETic Acceptableness by a Cast Gold Inlay and Porcelain Insert. Fig. 268. — Mesio-labial view of prepared tooth. Note the obtuse angle at median line of the gingival seat of the cavity and the acute angle between the mesio-labial wall and mesio-gingival wall. Fig. 269.— Note depth and definition of all eavo-surfaciC angles, pulp not involved. Fig. 270.— Mesio-linguo-gingival view of prepared tooth. Note extension of cavity linguo-gingivally, the acute angle created between the lingual and labial plates. This acute angle extends from the incisal end of the cavity to its extreme liuguo-gingival apex. Fig. 271. — A eavo-surface view of the prepared wax inlay. Fig. 272.— A lingual view of the prepared wax inlay. Fig. 273. — Wax inlay in position showing boxlike, or simple, cavity for porcelain insert. Figs. 274 and 275.— Mesio-labial and linguo-mesial views of the finished operation. Stress Index: Upward, outward and backward or intraalveo- lar Labio-Distally. 290 CAST (;()LI) AXn POIU'KLAIX INr.AVS Y\(y. 276. Fio-. 277. ri". 278. Fiir. 279. Fii--. 280. Fi- 281. Ki- 2X2. coij) l^•|.A^•s :.s\) tiik silicates ok I'okcki.ai x \'iiAv.s OF A Lekt Upper C'extkal ]'ke.sf.xtixg a Mesio-Disto- Labio-Ixcisal Deficiexov, Restored to Use axd Cosmetic Ac- CEPTABLEXESS BY A CAST GOLD IXLAY AXD SYXTHETIC PORCELAIX IXSKRT. Fig. 276. — Laljial view di' the preparod tootli. Xotc tlio lii'M'is at the incisal, mesial, and gingival walls. Fig. 277. — Lingnal view of the prepared tooth. Xotc large lievel linguo-giiigivally, and central keyed groove running into root canal whicdi has been filled. Fig. 278. — Lingual view of the wax inlay. Fig. 279. — Cavo-surface view and view nf prepaicil laliial surface of the wax inlay. Fig. 280. — Wax inlay in position n])on the tooth, wax carved out to provide for porcelain insert. Figs. 281 and 282. — Laliial and lingual views of the finished fiperation. Stress Index: Upward, outward and liackward or iittnniJri o- Jiir. Labio-Distalta'. 292 CAST GOLD AXD POPvCELATX IXLAYS Fio-. 283. Fig-. 284. Fi"-. 28.5 . Fio-. 286. Fio-. 287. Fin. 288. Fi-r. 28' llicii he l)iii-iiisli<'(l into lliis caNity, and the ])()i'('('laiii I'liscd into this matrix, oi' an ini])r( ssioii is taken ol* this sim])h' cavity, an amalgam die is iiuuh' as desc'i-il)e{l l)ero]'e, and tlie die is mounted in a small swa<;ini;" en]) so tliat it may he ])lace'd in a small Ajax swa.u'e, and the iiiati'ix s\va,i;(Ml into and onto the die. IJcfore any attem|)t is made to I'emoNc the matrix t'l'oin the ea\it\, direct or from tlie die, it is best to fill the matrix with a hit of wax and to l)i'in,L:,' this wax over the marf^'iiis of thci cavity to supplx' an ordinaril_\' indcst rnct ihle oi" unchan.^cahle i'i<;'idity to tlie matrix. Tlie matrix, cai'ryiii*;' the wax, is then invested in a paste ol;' silex and watei", or ' be securely held a,i;ainst displacement. The thinner the j)latinuin foil used for the matrix, and the greater the care given to the swaging of it, the more perfect a fit will 1)0 ohtained. For this reason a foil of V-^noo of an inch in thickness is used, and this is carefully ada])ted to the floor of the cavity with a ])ellet of cotton, held in the foil carriers, the ends of wdiich sliould be rounded. 'I'lie size of the pellet of cotton is gradually increased, until it is large enough to force the i^latinum foil along the floor of the cavity towards the walls and margins. The writer considers the safety depth or retention depth for these cavities to he no less than 1 mm. and they should l)e no less than l'(' to '2 mm. in depth; any depth greater than the latter uselessly endangers the integrity of the foil. After the more or less comjjiete ada])tation of this foil, the floor and walls of the cavity in the die, the l)uinishers are used to marginally outline the cavity, the margin of necessity pre- senting a smooth unl)uckled a])])earance. The swaging cu]) holding the die and the matrix, may then be placed in the loose end of the swagei', a rubber dam disc is l)laced over the matrix, and the ])iston of the swager is struck two or three sniait l)I()ws w itli a large horn mallet. r])on examination the matrix will be found to have become 2)erfectly adai)ted to the cavity in the die. As said before, this 296 CAST GOLD AND PORCELAIX INLAYS Fig;. 290. Fig-. 291. Fig. 292. Fiff. 293. □Q Fig. 294. Fitr. 29.J. Fiff. 290. GOLD INLAYS AND TIIK SILICATES OR TOIICELAIN 297 Sevkx Views of Another Type of Restoration" in an Upper Cuspid. The Formation of the Cavity, the Acute and Obtuse Angles are Clearly to be Seen in Figs. 290 and 291. Figs. 292, 293, aud 294 arc views of the inlay in and out of the tooth. P^igs. 29.5 and 296 are views of the finished operation. Stress Index : Uj^ward, out and forward and out and back- ward or intraalvcolar, Labio-Mesially and Labio Distally. 298 CAST COLD AN'D I'OIH'KI.AIX INLAYS Fi2-. 211 ; Fi2-. 298. Fi.M-. 299. Fip-. 300. Via. :!(ii. Fiir. ;502. Ki-. ;;(i; GOI.If INLAWS AND 'I'lIK SllJCATKS OK I'( )i;( 'Kl -A I X l!I)!) .Skvkx Views of a EiciHT Upper Cispid Pkicskxting a Pke- hex.so-Labio-Lixgl'o-Mesial Deficiency. Note carefully in Figs. 297 and 298 tlio fornuitiou ().) I^'or the ordinal)' idiciioiiiciia of rcllcci Ion and icrract ion llic cinissioii theory was siifficicnt ly sal islaclory, hut in oi'dcr to ('xj)laiii the plicnoincna of rcrraci ion and i»olari/a1 ion, IIic theory hccaiiic ()\('i'h)ad(Ml with a mass ol' hypotheses. Xewlon niahi- taiiied tliis theory to the time ol" Sii' Dax'id I>i-ewster. The Ava\(' theory ol" linlit was sii,i;-,i;('sted hy (li-imahli, I look' and others, used hy 1 1 iiy^ciis ( KiTS) to exphiiii (h)iihh' i-et'rac- tiou; it had few s])()iisors when re\i\'e(l hy ^'o^lll,^■ in tlie l)e<;iii- iiiiii;' of the nineteenth century. It ^\■as more Fully reeo<;nized and its ])heiioiiiena made clear hy 'rresiiel in ISIo, and on and until it liiiall_\' and dednitely sni)planted the emission theory. Accordin<;' to this tlieory, li^ht consists ol' vihrations in an all pervadin*;- elastic etliei', and these vihrations ai'e in direc- tions at ]-i,i;lit ani;'les to tlie directions ol" ])r()])a.i;ation ; and "rays ol* light" are mere lines showing' the direction of ])roj)agation of (and in isotropic media at right angles to) the corresponding ])ortions of the wave front. The wave theory readily exi)lains refraction; in refracti(Ui it assumes that the waves travel less ra])idly in the denser medium (which is found to he true) and it ex2)lains the accom- ])anying reflected wave; it explains douhle refraction, polariza- tion, ahsorption of light, interference, color and complementary colors, diffraction, etc. All these plienomena are explicable as j)lienomena of rhythmic disturbance of some kind and the wave tlieory really goes no further than to state this. The rhythmic disturbance may be one of position, wave motion, of stress, of electrical condition, possibly a twist in the ether. Clerk Maxwell holds that every portion of the ether in the j^atli of a beam of light is subject to rapidly alternating stresses transverse to the ray, and is, thei'efore, in a ra])idly alternating electric and also in a ra])i(lly alternating magnetic condition, and the curious relation now known to exist between beams of light and the field of force of a magnet lends su])])ort to this theory. The experiments of Hertz tend to ])rove that all the ])henomena of light, radiant heat and actinic radiation are re- (lnc(Ml to phenomena of electro-magnetic radiation between cer- tain limits of wave length. Although these facts hav(^ iio ini])ortant or direct bear- ing on tlu^ sul)i(H't involved, it mav he of interest to note that 304 CAST GOLD AXI) PORCELAlX IXLAVS the velocity of light was iirst round hy llimiiis, the eclipses ot Jupiter's satellites when they were at the greatest and the least distance from the earth; but it can be measured in the labora- tory by a purely experimental method. The mean of all ob- servations is that light of all Avave lengths, travels in vacuo with a velocity of 30,057,400,000 centimeters, or 186,772 meters, jjer second; in air with a velocity less than this in the ratio of 10,000 to 10,003. The length of waves can be ascertained from measurement at adecjuate distance to the fringes produced by interference, or by the use of diffraction gratings ruled with a known large number of lines to the inch (40,000 or more). The wave lengths of radiant heat, light and actinic radia- tions range from 1/660 cm., or 1/16,500 in. (the longest invisible heat rays lengthwise) to 1/1,300,000 cm., or 1/62,500,000 m. (visible actinic rays; the visible limits are 1/13,042 and 1/25,186 cm. The frequency or number of weaves per second accordingly range from 20 million per second, the extreme visible limits being 392 to 757 million of millions per second. In optical instruments a pencil of rays sometimes deviates from the point through whicli every component ray of the pen- cil should pass. Spherical aberration results from the spherictiy of length surface or of the mirror used to produce the image of the object. Chromatic aberration is due to the different re- frangibilities of the components of white light. Eef.: Tait, Glazbrook, Stokes, Preston and AVood on Light and Optics. REFLECTION AND REFRACTION AND ABSORPTION A surface on which a l)oaiii of light falls may be either rough or smooth. If it be rough, the greater part of the inci- dent light is irregularly scattered by the innumerable surface facets, to be reflected or dispersed in all directions; if it be smooth, a proportion (never the whole) of the incident light is regularly reflected or turned back in denfiite paths. A smooth dustless mirror is not visible to the eye outside the track of rays reflected from it. If that polished surface be that of a trans- parent substance (like glass) optically denser tlian the medium conveying the light of it, compai'atively little light is reflected: The more oblique the incidence, the smoother the polish, and PIIKXO.MKXA OK I.KJII'l' AXJ) COLOIt 305 tlie greater the (lirrci-ciicc hctwccii the ()])ti('al density of the glass and tliat of the medium in which it is immersed, tlie grealei' will he the ])i'()p()i-li()ii reflected. Less liglit will he i-e- flected from glass under water than will he reflected from the same glass in air. If the light travel in a denser medium and strike the hound- ing surface l)etween it and tlie rarei- medium, as where light is ascending through water and strikes its npix'r free surface, it will, if its o))liquitY of incidence exceed a certain limit, he al- most totally reflected, the small loss that ensues arising wholly from absorption while no light is transmitted into the air ahove. On reflection from i^olished surfaces we have so far as regards the directions of the reflected rays the following laws: 1. The incident lay, the normal (i. e., a line drawn per- pendicularly) to the surface at the point of incidence, and the reflected "ray" all lie in one plane, the plane of "incidence." 2. The angle of incidence (the aiigle which the incident ray makes with the normal to the reflecting surfaces) is equal to the angle of reflection (the corresponding angle between the normal and the reflected "ray"). These laws ai^ply equally to ether waves of all lengths, and therefore to light of all colors, no matter what the shape of the surface may be. 1. Uays which are parallel to one another l)efore striking a plain reflecting surface are jiarallel after reflection. 2. If light diverging from or converging towards a point l)e reflected from a plain mirror, it will appear after reflection to diverge from, or converge towards a point situated on the opposite side of the min-or and at an equal distance from it. In curved reflecting surfaces we inust trace out the mode of reflection of incident rays from each element or little bit of the reflecting surfaces; and through geometric workings, we arrive at the following propositions: 1. Parallel rays traveling parallel to the axis of a con- cave paraboloid mirror are made to converge so as to actually pass accurately through, i. e., the geometric forms of the para- boloid; and, of course, if the course of light be at the focus, the rays reflected from the niii'ror emerge ])ai'allel to one another. 306 CAST GOr.D AXD PORCELAIN IXLAYS In sijlierical rclk'c'tioiis tlu'iv is no acciirali' roeiis except for I'ays proceed iiiii,' from the center aiul ]-etiirniii,i;' to it. AVlien these reHections are small as compared to the dis- tance ot the center of curvature, they act approximately like ])ai'al)olic reHeclors for ])arallel rays. liays 2:)aralk'l to tlie axis, that is, rays from a distant source of light, are reflected so as to pass through the princij^al focus. Concave juiirors act like concave lenses. Refraction AVlien a l)eam of light, traveling in a transparent medium, imi:)inges ol)liquely ni:)on the surface of another transj^arent medium, a part of the light is reflected, and a jDart of it enters the second medium, hut in so doing it is refracted or hent ont of its former course. The incident, reflected, and refracted rays lie in one j^lane. Snell, in 1621, elucidated the following law of refraction. ''The sine of the angle of incidence ])ears to the sine of the angle of refraction a ratio which remains constant for any two media, whatever be the angle of incidence." This law of refraction is an immediate deduction from the ])roperties of wave motion; if we assume that the speed of j)roim- gation of light is different in the different ]nedia. When a wave 23asses over the surface of water, the direction of propagation is perpendicular to the crest or throngh the wave motion. In like manner we iiuagine the ray of light to he j^erpendicnlar to Avhat is called the wave front, which ^^ropagates itself throngh the medium with the speed of light. So long as the light is confined to one and ilie same medium, any wave front on Avhich we fix our attention will travel forward so as to ever he ])arallel to its original position. In Fig. 304 let AxVA" i-epresent one of a pencil of rays im- pinging ohrKjudx' on the sni'face !>. I'he wave IVont may be repi-esentcil l)y a line tlii-ough A j)ei-peiidicular to the direction of pi'o])agation. At the end of a certain time the Avave front is at A' ; aftei- aiiothei- int»'i'\al of e(|ual duration it is at A". Dur- ing tlie next e(|ual interval of time, a graduall>' diminishing breadtJi of wave is ti-aveliiig the oiigiiial medium with the original sjjeed; while a steadily widening portion of the wave I'll KNo.M i':.\'A (»!■' l,i(;iri" anh coi.oi; ,*>()( ri'oiil is ciilcriii^' ilic second iiKMliiiin. IF we suppose ilie s])ee(l of prop;i,L;at ion of llie disl inhnnc' to ))e less in the second incdimn, it is clear that the <'iid A. which lias Ix'cii ti'av('liii<»- in the second mediiim, whil" the end A" has still been in the first mediiiin, must have ti"a\"eh'(l ovei- a sliortei- distance, 'i'lic wave i'l'ont through A will then pi-oceed to in()\'e in the second mo- cliiiin, so as always to I'emain j)aiallel to its ori<;-iiial direction ill this inediuin, hence the lel'iacted wave front moves on at a less iiKdination with the interface se])aratin<'- the media than that with which the original wave front imi)in<;ed n]>oii tlie in- terface. A,i;ain the distance ot A" from the surface JJ, as meas- nr(Hl aloiiii' the ra\' will ))e greater than the distance from the Fjo-. 304. same surface as measured alon^- the ray, in the ratio of the speeds of proj^agation in the two media. This ratio is the ratio of tlie sines of the angles of incidence and refraction as given in SnelTs law, and is caUed the refrac- tive index of the second medium as compared with tlie first. Thus physically, the refractive index of any transi^arent medium is the ratio of the speed of propagation of light in empty ether to its speed in the medium, the medium in which light travels more slowly, is said to liave tlie greater optical density. If we regard A A' to he the original ray traveling in the denser medium being refracted as A" A' A in the less dense medium, we just reverse the direction of the rays without any change in the relation of the angles, except that the refractory 308 CAST COLD AND POlU'Er.AlX i:M.AYS ra\' is now IxmiI ;n\;iy from llu> normal or ixM-pcndiciilar to the surface. Ima^-iuc the incident ray in tlie denser medium to be- come more and Jiiore oljlique to the interface, the refracted ray Avill tend uiore and more to paralk'lisni ^vith the interface, and linally for a dehnite inci(h^nce will pass alonij,' it. For liigher incidence than tliis critical an^ie, no refracted ray will pass out; the light will l)e wlioUy reflected witliin the denser medium leaving- out of account wliat is absorbed at the interface. Tliis angle is the angle of total reflection or the critical angle. Absorption If a ray of sunlight l)e allowed to fall upon a glass prism, it will be found, on emerging, to be split up into a color band, which is called the solar spectrum. Conversel}^, these colors, when combined produce ordinary white light; most substances when ex])osed to sunlight have the power of reflecting one or more of these coloi's, and of absorbing the rest. Thus, if a ray of sunlight falls on a patch of grass, the grass absorbs all the colors of the white light except the green, which it reflects. These reflected rays meet the eye and convey to it a sensation of greenness; and hence the grass appears as a substance green in color. Similarly a poi^py is red, because it absorbs all the rays except the red, which it reflects, and thus assumes a red hue. \n the case of a white flower, none of the colors of the s])(H'trum ai-e absorbed; all are reflected. On the other hand, a l)lack cloth absorbs all of the rays and reflects none of them, and so appears black. A red liquid or glass transmits only the rays at the red end of the spectrum and absoi-bs the others, and so wilh the otlici- coloi's. A cobalt blue glass transmits only bluf rays, and the extreme red rays, while a glass colored red with copper oxide absoi'bs llie ])lue and transmits the red. If then these two glasses be j)lac(M| one in fi-ont of the other, and oi-dinary white light he allowed to fall u])oii them, the combina- tion ])erinits only the exii-eme I'ed rays to reach the eye, thus producing a vei-y ])ni-e deep icd. This method of combining different absorl)ing media is employed to ol)tain definite coloi-s in purity; thus while light ])assing through these cells, one con- taining aniline Mnc, one eliromale of potash, and one coi)2)er or PJIEXO.MEXA OF I.ICllT AND COLOIl oi)[) Hiil])liat(', is successively robbed of its bbie, yeHow, and r^'d rays, and the eiiiei'^'eiit li,i;lil is pure green. 'Phe absorj)iion of li^ilit by ♦••ases follows a dilTerent biw. Tht' while li<;hl falls on a cool ,i;as, the <;'as absorbs only those i-ays which it wouhl itself emit if incandescent, and leaves dai'k' lines in their ])laces in the s])ectruin of the light. The vapoi' of sodium, which is yellow, when incandescent absoibs yellow rays, when cool. On the other hand, if the gas be incandescent, ab- sorption still takes place, but the light of the gas is sul)stitute(l in the spectrum for the light absoibcd, ])roducing a l)right yellow" band there. The color band, called the solar spectrum, is found u])on examination, to be crossed by a number of dai'k lines. Jf the source of light be changed, the spectrum changes with it. In the siDectrum of the wdiite light of a candle, for instance, or that of the oxyhydrogen lime light, the dark lines vanish and we have a continuous spectrum. Again, if light from an incandescent gas or vapor be examincMl, we get, in general, a sj^ectrum con- sisting of a clehnite number of bright lines on a dark ground. Every gas or vapor yields a different and quite characteristic spectrum. The salt of sodium l)nrned in a Bunsen flame, will cause the flame to become yellow^, and the spectrum consists of two narrow lines of yellow^ light. Similarly potassium gives a violet flame, and two In'ight lines in the red and one in the violet of the solar spectrum. Strontium colors the flame red, and has a number of lines in the red, one in the orange and one in the blue ijortion of the spectrum. Though perhaps having no direct bearing upon the color problem as it concerns our su])ject, it is of interest to note that these bright lines, in the si^ectrum of the various substances mentioned, correspond, in position, to certain of the dark lines of the solar spectrum, and it has l)een estal)lislied that the dark lines indicate the jjresence of these metals in question in the sun. As said ])efore, when white light falls on a relatively cool gas, the gas absorbs these rays that it would itself emit in incan- descejice. Thus \\-e might liax'e in a room, a source of liglit giving out all ])()ssil)le waves of light, fi-oni red to violet. If this light were h^d through a screen of sodium vapor, the screen would absorlj those rays wdiose wave lengths corresponded to 310 (.'AST COl.D AND TOIU'ELAIX JXLAVS tlie bright sodium linos in tin,' Yellow ])art of the spectrum. These rays l)eing removed, there would be left two dark lines in their pUices. This is precisely what happens in the case of solar si)ectrmn. The sun is a source, giving out light of all l)ossible wave lengths; as the light passes through the sun's atmosijhere, it encounters, say, the vajDor of sodium. This vapor absorbs the rays whose wave lengths correspond to the yellow lines of the sodium spectrum and leaves dark lines in their ])laces in the solar spectrum. By observing these ahsorj)tion lines in the solar and stellar spectra, the jjresence of various terrestrial elements have been proved in the sun and the stars. The refractive index of a transi)arent medium is different for different kinds of light. "When white light passes through a jjrism, the diiferent colored rays of which it is composed are bent at varying angles from the original conunon source of direction. They are said to be disj)ersed. The disi^ersion for the given prism depends upon the difference of the refractive in- dices of the extreme rays of the visible spectrum. It A^aries with the substance and the angle of the ])rism. In general rays of short wave length are more refracted than rays of long wave length, but in some refracting media this law partly breaks down, and the dispersion is then known as anomalous disper- sion. (Ref.: Schellenon, "Spectral Analyses," Marshall AVatts, ' ' Spectrum Analysis, ' ' Baly, ' ' Specroscopy. ' ' ) The impact of ether waves of a certain particular frequency induces in the eye a particular color. Color then is a sensation and really has no material existence. The eye can recogni/.e no other waves save lliose having a fi'equeucy of from 'M)'2 to T-")? billion ))ei- second. AVithin this lange, each number, each frequency has its own color. The ex- ti-eme visible red of the rainbow oi- spectrum is produced by about 892 billion; the extreme \i()let by al)out 757 l)i]lion vibra- tions pe)' second. Between these the eye may rest U])()n cei'tain distinctix'c coloi's; and the rr('(|iicii('i('S coi'i'esijonding to tin; res])ect i\-e coloi-s are: lv('<|, 4I)lI-4; oiangc reel, 4S4 1 ; orange, ^)iy.\-'.\; orange yellow, ')\]-'2; \clh)\\. r)17-."'); green, ."')7<); bine green, .")!)] -4; cyan l)lue, ()()(); blue, b.').").!'; xioh't bine, ()Sr).S; pure bine, 740..") billion ])er second. ]'iii':.\().Mi';.\A oi' i.iciri' axii coi.oi; 311 Li^lit duo to wave uiotiou ol' one siiiij)l(' j'requoiicy would ))(' lioiiio'-'ciicous, or iiioiioclii'ouiatic, light. If it wore visible, it would pi'oducc llic -iiiiplcst coloi' sensation. TIn' ligld of l)uni- ing' sodium is a comiKjuiid of two yellow lights ('orresi)oiiding to their resjjectiYe wave frequencies of 508.9 to 510.6 l)illion vibra- tions per second; and this is tlie nearest we have as yet readied to nionochroiiiatic light. The eye takes up any congeries of monochromatic light impinging simultaneously upon the same spot in the I'etina, and the rcsultiiig sensation is always that of a single color, not necessarily I'esembling any of the coinponcnts. (ifccii (iihI riolcl lif/Jit hloidcd In different propoytions produce all the 'nil er mediate hlues. Nearly every example of, Avhat Ave call colored light is in real it j" an admixture of several monochromatic lights. White light is usually due to a simultaneous impact of wave motions of all visil)le frequencies; but the sensation of whiteness may be produced by the sinudtaneous im])act on the retina of two suitable spectral coloi's such as yellow and ultra-marine blue. Colors vary in liue, in j/iirili/ and in liiniinosity. The hue determines the name. The purity or absence of admixtui-e with white light de- termines its richness (i. e., vermilion reflects 80 ])er cent of red light mixed with 20 ^qy cent of white). The luminosity or brightness determines the shade or tone of color. Interference with any of these will cause a sensation of the impression produced upon the retina with a corresponding vari- ation in the color. The color of irans])arent objects is due to selective ab- sorption. A red object seen through greenish l)lue glass aj)- l)ears black; greenish blue glass absorbs the light from the red object. Hold the same piece of glass up to the sky, and the red lights which aie components of the white light of "day" are cut off; Avhat light ])asses through will ])r()duce a sensation of greenish 1)1 uc The color of a trans])ar('ut body will also a])]iarently de- 312 CAST GOLD AND POrvCELAIX INLAYS peiul 111)011 tile tli*K'kiiest> ol:' the layer examined; a lliiii layer of iodine Ya])or aj^pears in dayliglit to l)e ])iirj)le; a thicker layer ajDpears blue. Before a nonliiiiiinoiis o])jeet can be seen otherwise than by transmitted light, it must rellect light; if it does not it will ap- pear black. Pour a colored liquid into a deep black vessel, it will reflect no light to the eye of the observer. It absorbs all the light and reflects none. Sprinkle a white i30wder into the vessel onto the surface of the liquid. AVhite light enters the vessel, it is reflected in all directions by the powder, but it is in part absorbed by the liquid and the color of the liquid is revealed. Of exactly the same kind is the reflection of light by a solid object. Bodies allow light to traverse them to a very small depth, and then by internal reflection the light is turned back in all directions; absorption comes into play, the result being that the object apjoears to have a definite color. If the light supplied to an object contains none of the kinds of light which it can reflect, the object appears black, or color- less; flowers looked at by the yellow light of burning sodium will appear colorless or black imless the flowers are yellow; surface reflection modifying the result. Color is not always due to selective absorption. A haze is blue if it consists of fine enough particles; these cause repeated reflection and at each reflection the light becomes bluer; because these rays which would have been most refracted (the blue and the violet) are most largely reflected. The color of the sky is that of a haze i-eflectiug light downward. (Kef.: A. H. Church on "Color," 1887; and ''Colour" by C. T. A¥hitmell, 1888.) There arc three primary colors and these plus a modifier are all the equipment the porcelain worker really needs. He may for convenience use several shades of the three primaries. A primary coh)]- is llia1 w liidi can iiol be made l)y c()ml)iiiing other colois. The three ]nimaries ai'c ncIIow, vrd, and hluc. These may be considered the thi'ce coloi's of creation and iiicy ai'e analogous \() light, heal, and sliadc Yelh)W rej)r('S('nt> liglil, life, and acti\il>'; and red repre- seiiis cohjr oi' wai'iiilli, or lidincss, if yon j)l('as('. riiEXOMENA OK LKUIT AND COLOR 313 Blue represents shade or tone. The modifieis are Avliite and bhick, wliich are considei'ed the acme of liglit and shade. White or Idaek shoukl not l)e considered as colors. It seems foolish, and it is foolish that assertions are made, first, that a certain combination of coh)rs will produce white and then that the same combination of colors will result in ])lack. For some time a color wheel was a part of school equip- ment, designed to demonstrate that Avhite was a coml)ination of all colors. The three primary colors, yellow, red, and blue were placed on the disk, and it was revolved at high speed. But the ini- mary colors on the disk were usually of a light tone, white form- ing a great part of them, and the blending brought about by rapid revolution of the disk resulted in a disk of neutral gray. If we comliine yellow, red, and blue, in which uo white is present, a very dark shade will be produced, and this will be the nearest approach to the absence of all colors, but it will be very far from a true black. Any two primary colors mixed in equal parts form a second- ary color. These are three secondary colors: Yellow Blue I ^ Red 1 ^ Blue 1 -p. . r"'*" Yellow }0™"8'' Eedr^'T'*' An im2)ortant claim set up by some schools that the three secondary colors are the true j^rimaries, must be here combated. When a green object is looked at in a strong light until the eye is saturated with the color, its complement, red, is j)roduced in the eye, and if the eyes are closed the object will appear a bright red, instead of green, its natural color. The same is true of the others. Purple will produce yellow in the eye, and orange will j^roduce blue. Plence the claim of i^rimaries for the secondaries. But a more careful study and observation will show the fallacy of such claim. The action of complementary colors is always reciprocal, and the ]-evei"se action of these colors is much more marked. Red will produce green in the eye much more (piickly and brilliantly than green will produce red. ol-t CAST C!OLI> AND TOltCELAIX INLAYS Yellow will produce, or, rather, induce puri)le, and blue will induce oraii^i2,e in the eye mucli more quickly than the reverse. That there is one action of color in light and another in l)ignieut is not correct. The action is the same in both. Sanford proves this by the following experiment : From a piece of thin looking-glass, cnt a couple of little mirroi-s one-1'onrtli of an inch in width and an inch in length; stick jjins in lengthwise throngh two small corks and glue the backs of the mirrors on to the toj^s of the corks over the heads of the i^ins, so they may be stuck into paper and set at any desired angle. Throw the i^rismatic colors through a iDrisni onto a sheet of white paper on the wall, and i^lace another sheet of white paper on the wall opposite the sheet uj^on wdiich the colors are shown. To prove that green is a secondary color in light, as well as in pigment, produce it from the adjoining color on each side, blue and yellow. Stick the mirrors one in jDure blue, i-eflecting it onto the white jjaper oj^posite; and the other in i)ure 3'ellow, throwing them together on the opposite paper, the same green shown l)y the jirism will be produced. The same exi)eriment should then be made Avith the mirrors in yellow and red for orange, and in l)lue and red for purjjle. This fully establishes the secondary character of the three colors, for no one A\ho has carefully studied this subject will assert that a coloi' ])roduced by combining two other colors is in any sense a primary one. Xow try the o))])Osite ex])erim('id ol' i)roducing the blue by combining llic adjacent colors on each side ''the ])ur])le and tiie green,'' ami the yellow l)y combining green and orange, and the red by combining orange and jjui-jjle, or any other combina- tion you may wish to try. Note the uttei* I allure of the experi- ments anropor- tion, and so we would get an a|)])i'o\i]iiat(' ahsenee of color. Only two primary colors are comhined simultaneously in the l^rism or rainhow; for this reason no tertiary coloi"S are present in prismatic or i-ainl)ow colors. An intermediate color is a color ])etween a primary color and a secondary color, and is made hy ccmihining a i^rimary and a secondary in equal i)arts; or it may he made directly from the l)rimary colors l)y mixing two primaries in the proj)ortion of three parts of one to one ])art of the oilier. There are six inter- mediate colors: sulphur (yellow-green) ; saffron (yellow-orange) ; nasturtium (red-orange) ; garnet (re(h])urple) ; campanula (hlue- purple) ; and turciuoise (hlue-green). These six intermediate coloi-s ai'e usually divi(k'd into a grade of five shades raiigliig IVoiii Ww j)i-iiiiai'y to the secondary hetween which eacii coh)]' slaiids, and Ihis gra(hiati()ii, together witli the niultitu(h' of shaih's of primaries and secoudai'ies, pro- vides an endless varietv of color. 116 CAST GOLD AXD PORCELAIX INLAYS Fig. 305. A. YoUow, jiiimaiy. JJ. Ked, piiuiiiiy. C. Blue, x^i'i"i^''.y- D. Purple, secondary :^ one i)art B + one part C. E. Orange, .secondary =; one part B + one part A. F. Green, .secondary := one part C + one j^art A. G. Olive, tertiary :•= one part Z> + one part F. H. Russet, tertiary = one part D + one ])art E. I. Citrine, tertiary = one part E + one part F. J. .Sulphur, intermediate. '.'A. + iB + 1C', or lA + IF. K. Turquoise, intermediate. 'AC + IA, or IF +1(7. L. Campanula, intermediate. '.iC\-lB, or D + C. M. Garnet or red puij)le, intermediate. 3B + 1C. N. Nasturtium, intermediate. ?>B + 1A, or IB + 17?. 0. Saffron, intermediate. ?,A + iB, or 1.1, + IF. IMIIOXO.MKXA Ol" IJCIIT AND COl-Oi; IWI Complete Chart of the Prismatic, or Rainbow, Colors It will he noted that both in tlie color f^'uide and in tlio ])rismati(' cliaii, indigo d()(\< not api)ear, altlionfth it was in- cluded by all eolorists froiii Xewton's time u]) to 1890, when the discovery was made that, bein<;' a comhiuation of black and blue, indig'o never had Ijeen ])resent and should not be included in the prismatic colors. As will be readily seen, all colors come from tlie three ])rimary colors, red, yellow and blue. The secondary and inter- mediate colors are formed in the prism or rainbow by a blend- ing of the primary colors; the red and yellow blendinft- together and forming all grades of orange, from red-orange to yellow- orange; and the yellow and blue blending together into all shades of green, from yellow-green to blue-green. Purple is formed both at the top and bottom of the rainbow, by reflection of the red and blue, which are refracted out of a direct line, and consequently reflected on the inner surface of the prism or rain- bow as shown in the chart, the red being reflected from the bot- tom into the blue at the top, thus forming purple. Violet is purple in a diluted form, and as it is a reflected color in the rain- bow, and consequently weak, may reasonably be called violet, but is in reality purple. The blue is also reflected into the red, and j^roduces pur- l)le at the bottom. Colorists, not having looked for this, have failed to observe it, but it may be plainly seen in any bright rainbow. The red reflecting into the blue at the top produces all grades of purple between pure purple and red-purple. It will thus be seen that all colors appear in the prismatic or rainbow colors, excepting the tertiary colors — citrine, russet, and olive — which, being a simultaneous combination of all three primary colors, cannot themselves exist in the prismatic colors. Harmony of Colors The way color affects the eye is not only very interesting, but is very important to every person who has eyes. "When the eye looks at a coloi-, not the color itself but its opposite, called its complementary coloi-, is absorbed by the eye, and if 318 CAST COLD AND I'OltCKI.AI X IXLAV^^ tlio eyes are cIoscmI, tlic oljjcct ^\ill he seen, not in tlio color tlio CYC saw wlicn open, Init in its coiiiploiiieiitary color. If a I'od color is looked at until tlie eye is satnrated witli the color, and tlie eyes are closed, llie oljject will he seen, not in red, bnt in a hriglit groiMi. It' the eye sees a l)ri,<;-lit yellow until it is tilled with the color, it will he seen witli closed eyes in a rich 13urple. Therefore when one color is seen it is important that the next color looked at shall harmonize with the color Nature has formed in the eye, or an unpleasant shock will he expe- rienced ctnd the pleasing sensation of harmony destroyed just as effectually as a clash of sounds shock the ear. This creation of the complementary color is not confined to the eye alone, Init all Xature capable of reflecting color shows the same action; for example, a yelloAv sunset reflects purj^le in all cloud and snow shadows. The matter of comj^lementary color is a simple one, not dif- ficult to understand, and everyone should learn it. To each color there is one other color which is comj)le- mentary. A complementar}' color is one which supj^lies what is lacking in the other; for example, green, which contains yel- low and blue, lacks red, therefore, red supplies what is lack- ing in green and is its complement, and, vice versa, green is the com23lement of red. In every case complementary colors are reciprocally com- plements of eacli other. In the color guide, the complementary colors are shown o])])osite each other. Eed and green are com- ])lements, as are yellow and jmi-ple, as well as blue and orange. It becomes a sim])le matter of remembering tliese three sets of complements and Icni-ning to balance shade for shade, and tint for tint. The more delicate these halaiices, the Mioi-e sul)tle and ex- quisite may he the effect of coloi' hai'nion\' ui)on the eye. Rule 1. — ('onii)l"nien1ary colors, when ])laced side by side, brighten each olliei-. It is impoi'tant 1o nndei'stand well llie following simi)le, na1ui-al ininciples. As has been stated, each color produces its coniplcnienl in tlie eye. If one look's at I'ed, green is created in the eye. This is not a delusion hut a ])ractical fact. If one lias seen led, and there is conse(iuently green in th(^ eye, if I'll i:.\().M l';.\A Ol' IJCIIT AND COLol; 319 llic ('\(' liini from red to ii'i-ccii, thai is, if llic ,i;;r/(' \)v ({iiickly sliit'lcd I'loiii a i-('(l lo a ni'ccii siii-racc, ilic .ni'ccii wliicli lias l)een ])i'()(lii('('(l ill llic eye Ity llic I'cd, will add lo Ihc ^rccii wo ai"o looking' at and il will aitpcar iiioro brilliaiii than il would have a])poai'('(l if llic cNc had iiol jiisl been lookiii;;' at red. HMiis ox- ])laiiis the piinciplc of llic lirsl rule in the hai'uiouy of coloi'. It will thus he understood that if hrilliaucy of color is desired it must be attained by the apjjjicatioii of lliis ])iinei])Ie. Two ('ouii)leiiientary colors must in souie way be so ai-i'an<;ed as to a])])ear in juxtaposition. liulc v. — C^oinplcincnlary colors, ^vhen mixed to^'clhcr, kill each olhei'. We must now conic to the mailer of subduin<;- instead of lici^^htening color, which may easily ])e done by ol)servinf;- an- other action of Nature. The same color which, if placed be- side a color, will bri<;hten it, if mixed, will lill it. If red be too red, f^reen is the only color that will take the redness out, or subdue it; and, vice versa, if green be too green, red is the only color that can subdue the greenness. This fact is of equal force with every other color; rod and green are complements and will not only brighten each other in juxtaposition, l)nt will negate each other when mixed together. The same is true of yello^\' and jDurijle and of blue and orange. By observing these rules, an}^ desired effect in the harmony of color may be produced; a color may be heightened by the simple method of placing its complement next to it; or sub- dued (if less brilliancy is desired) by mixing its complement with it. The symphony of practically one color produces the comjjlement in the eye, and if this created comi^lement is not neutralized by the actual presence of the same color, it blends in the eye with the local color and subdues it. The range of comjilementary colors is not wide and com- plex, but very simi)le and contined strictly to the three j^ri- maries, the three secondaries and the intermediate colors. If a color be a primary, a secondary is its complement. If a color be a secondary, a primary is its complement. If a primary color has but a small amount of another iiv'i- mary in it, thus turning the predominating color a little away from the ])i-iniary, its com]ilement will contain just as much CAST C;OLD AND POKCELATX INLAYS INTEnMKDIATE COLORS Yellow Yellow Yellow Yellow Yellow Caiiipamila- ^Blue (Secondary) (Primary) -Purple - Blue-Ecd Turquoise Blue (Secondary) Yellow and reen - \ Blue Sulphur or Yellow^Greon (Secondary) reen - Yellow and Blue Saffron (Secondary) •Orange Yellow and Rod Nasturtium anict (Secondary) Orange - Yellow and Tied -Red (Secondary) — Purple- Red and Blue 'IIKNOM K\.\ OK IJCIIT .\.\l) COLoi; 821 more ol' tlic iciiiainiii,!;' lliinl pninaix . Fov example: IT red has a little yell()\\- in it, tiii'iiiiii;- il lowai'd nasi iii1 iuiii, or i-od-oraiift'o, its coiiipleiiieilt L;i-eell, lilllst liaxc just lliat llllicll more Mile ill its ('oiii])ositioii, turning' it toward tur({iioi.se, oi- l)liie-<;reeii. In tliis way tlie six iiiterni< diary coloi-s may he compleiiieiits. A fact to he reiiiemhered in the harmony of colors is that white oi- hhu'k' added to any one of the piimaries, ])r()du('es two colors of (piite opposite ( ffect, that always harmonize with each other, as they are virtually li,i;lit and dark of the same color. White a,d(le(l to yellow will pioduce straw, or cream, color, according- to the yellow used; and hlack added to yellow pro- duces olive, therefore, straw, or cream, and olive produce ])ink; hlack added to red produces maroon; hence jjink and maroon will alwa\s harnionize, AVhite added to Idue produces azure; hlack added to hlue ])ro(luces indig'o; hence azure and indigo will always harmonize. CHAPTER XXI THE PORCELAIN INLAY If we now lalve up tlie consideration of the porcelain inlay as a distant oj^eratiou by itself and not in combination witli gold, we shall iind ourselves compelled to designate the indica- tion and contraindication for the i^erformance of this operation, and we find tliat the best general rule that may be laid down would resolve itself into dogmatically stating that porcelain must be used where gold would be objectionable because of esthetic reasons. In other words, all the surfaces of decayed teeth which would upon being restored be exposed to view, must be filled with a material which will not be objectionable to the eye, providing the conservation of the teeth would l)e brought about to a satisfactory degree. On the other hand, another prin- ciple that might be almost general in its aiDplication is in my opinion, well stated in this following sentence: No occlusal sur- face of any tooth which would upon restoration be opposed by a natural dental organ, should be restored by porcelain, when other materials may be had for that purpose. I realize that I lay myself open to severe criticism on the part of those who blindly and fanatically follow the porcelain call, ))ut I would call the attention of the ])ractitioner and the student to the fact that ])r()i)eily fused, ])()rcelain is infinitely harder in texture and resistance than the natural tooth enamel, and so under the stress of nuistication the latter will suffer by attrition, and the damage created will far outweigh the tem- ])Oi'ai\v estlictic satisFacliou obtained by the operator in com- l)leting his operation in Hie inateiial mentioned. It is fai- better to icstore the occlusal surface of natural teeth which lia\-e deca_\(M| in a material that is somewhat softei' or more yielding than the natni-al tooth enamel, and thus run tlie risk' of having to peilorm tiie operation again rather than endangei- the integrity of teeth that are in no way involved hy d<*cay. It would seem too that j)orcelain is a material jiecu- 322 TIIK I'OIK'KLAIX IXI,AY oJ.) liarly n(lai)t('(l to r('j)laeiti^' liiosc jiails of natural tcctli tliat arc ill {'lose |)r().\imity to the ^iini tissue, and tlie reason for tliat may he round in the fact that poi'celain is vei'y dense, and may he fused to a \-er\- lii,i;li polish, so that U|)oii eeineiitat ion into i)hu'e, it will ])rescnt no I'ougli surfaces for any feniient products to attach themselves to and so invayraiii, in an elahorate nioiiograi)li on the suhject of por- celain iiday work, practically concedes to porcelain the realm of the entire inoutli, preferring it to any other filling material, but I think that he was mistaken in his deductions and in liis conclusions, for the reason stated above. The dental porcelains as we use them are composed of' silex, kaolin, and feldsjjar, iluxes and pigments, or coloring- matter. Silex is an oxide of silicon, an infusil)le substance insol- uble in all acids except hydrofluoric, slightly solul)le in caustic alkalies, and forms about 14 per cent of the ])asal mass of porcelain. It adds to its strength and gives it a translucent appearance. Kaolin or silicon of aluminum, consists of an aluminum ox- ide, silicon oxide and water, sometimes spoken of as disinte- grated feldspar. Through natural decomposition feldspar loses its potassium oxide by the action of w^ater and other agents. Kaolin forms about 4.5 per cent of the porcelain. It is a highly refractory clay when heated alone, but readily unites with feldspar when mixed with it. It supplies the porcelain with stability of form, which permits it to he molded and carved be- fore being fused. Feldsjiar is a duplicate silicate of aluminum and potassium. In other words, it is comj^osed of aluminum oxide, j^otassium oxide, and silicon oxide, so that it would seem that the differ- ence between feldspar and kaolin is the possession by the for- mer of potassium oxide, and the possession of kaolin of the water of crystallization. Feldspar composes al)out 82 per cent of the basal mass of porcelain, a highly refractory material, almost infusilile in ordinary electric furnaces. In order to increase the fusibility of this basal j^orcelain and make it possible for the general i)ractitioner to use it in his 324 CAST COLD AXl) POlH'Kl.AIX IXLAYS jiractirc, llii.ves are added; siu-li suhstaiiccs as sodium l)orale (Xa340:): sodiiiiii carbonate (Xa,('(),); potassiiiin carbonate (K.CO,,), or <;'lass wliicli contains oxides of potassium or sodium forming tlie greater j^art. All these tiuxes are ground together with the ])oreehiin; then upon fusing a cheniieal change takes ])lace forming an indefinite compound, from wliich none of the original ingredients can be removed except by some jn'ocess Avliich involves tlie destruction of other ingredients. The i)igments or coloring matters most commonly used in the manufacture of dental i)orcelain are i^recipitated gold, jjlat- inum, purple of Cassius (the oxide of gold and tin), the oxides of gold, titanium, manganese, and silver. The colors produced by the use of these pigments in varying proiDortions are hues of red, yellow, l)lue, green, l)i-own and gray. Dental jiorcelain may l)e divided into high- and low-fusing jjorcelain. High-fusing i)orcelain is one that will fuse above tlie melting point of pure gold, and low-fusing porcelain some- where below that point. Byram states that any enamel bod}^ can be fused on pure gold i3roviding enough time is given. Some low-fusing porce- lain will fuse above the fusing point of pure gold, provided the requisite heat to fuse pure gold is obtained rapidly. He also adds that while the above distinction seems to meet all practical requirements, it is unscientilic and its only value is to make a convenient distinction between the two classes of porcelain for ])ractical usage. He also makes the following distinction between high- and low-fusing porcelain: High-fusing porcelains require more than five minutes to fuse, while low-fusing jwrcelains require less 1lian (ive minuies to I'use at 2,000° F. ft is impossible to fuse aii>- of tlie liigli-rusing ])orcelains at 2,000' F. in five minutes, and it is also im])()ssible to keej) any of the low-fusing ])orce- lains in contact with a heat of 2,000 l'\ loi- fnc minutes with- out becoming oveiTused. He divides j)orcehrui bodies into l)asal, or foundation, bod- ies, emimel bodies, and glazes. All hasal and I'oundation bod- ies he says are high-l'using poi-celaiiis, w hile enamel bodies and glazes ai'c <'i1h('r lii.Lili- or low-fusing porcelains. 'I'lie lia>al hodies ai'(^ used in crown and hridge work For the TIIK TOItCKI.AI X I.XLAV '^'27) coiistriicl ion of liaiid-r.-ii'NiMl Icclli. and llicx' i'('<|iiii'(' a spcciallN' coiistniclcd I'liniacc in oi-dcr lo niainlaiii flic iidcnsc heat iRMdcd to fuse llicin. TIk' I'oundalion and enamel hodies nii,i;ld meet tile i'e(|ni I'emeids I'oi' iiday woi'k and it is best I'oi" the o])erat()r who intends to pert'ecl liimselt' in this work, to limit liis ex])eriments to tli( so lattor ])0(lies. Tliese ))oi('(dains used i'oi- inlay woi'k may he mixed \vitli alcohol or tliey may ])e mixed w itii watei'. The lattei- ])ro('ess ,i;ives a hody more easily cai'ved t lian the fonnt i'. From an elaborate sei'ies of ex])eriineids l)yi'am de(lncted the follow ini;-: 1. Porcelain has no definite fusing' point. 2. By ])r()loni;-ino- the time of exposing to heat, a thoroughly fused ];oi'('elain may he ol)tained at a comparatively low teni- jjerature. I do not agree Avith Byram in this respect; at least 1 contend that the reasoning of Byram in this instance was in- correct, and that the amount of heat present in the electric fur- nace nnifile at the time of the fusing of that porcehiin was greater than was indicated upon the i^yrometer or other instru- ment used by Byram in determining his degree of heat. The effect of heat u})on the porcelain is cumulative, and the vibra- tions of the heat waves in themselves tend to create heat plus, and thus even though the degree indicated upon his instrument was lower than he thought would be required to fuse that por- celain, he must have of necessity been in possession within his muffle of the requisite^ amount of heat to fuse the mass. So I would rather have it understood by tlie student that the sec- ond deduction of Byram is not an axiomatic truth. o. "Porcelains fused at a lowxn- temperature and for a longer time will maintain their characteristic color, and will 1)e more homogeneous in texture,'* which I would rather have read as follows: "The more carefully porcelains are fused and the more slowly the heat is allowed to permeate them until they reach the fusing ])oint, the more homogeneous will they be in texture, and the more certain they will be in color." 4. Low-fusing jiorcelains can be made of high-fusing porce- lain by repeated fusing and grinding; which, while perhaps true, seems to be an anomaly wIkmi we consider the fact that each fusing and grinding disi)oses of ])art of the flux, and so we 32(i CAST COLD AXD r(~)rvCELATX INLAYS liave ultimately tlic basal ])odies or the oiuiinel bodies to deal Avitli, botli of wliieli are lii,i;lily retVaetory eoiiipounds not read- ily subject to fusing. 5. If a piece of porcelain is tlioronglily fused and more 13orcelain is added and fused, tlie first layer will be slightly over- fused. In the process of applying porcelain in layers and fus- ing each layer, the underlying layers will l)e slightly overfused and somewliat lighter in color, which should carry the warning to the student that porcelain restorations should be biscuited until the required amount of bulk, outline, and contour has been obtained, and that the jjorcelain restoration must be fused only once. 6. A small mass of porcelain is more readily affected by heat than a larger one, and as the size of the mass of porcelain increases, just in that ratio does the length of time necessary to fuse it increase. 7. Porcelains containing a large percentage of flux are more easily affected by bubbles than tliose that are more nearly com- posed of the basal ingredients. Very readily comprehended when we realize that the tendency of all fluxes is to leave the porcelain in the form of gases and that these gases forcing them- selves into and between the molecular spaces of the porcelain, prevent homogenous arrangement of the molecules, 8. It is more difficult to maintain the characteristic color of low-fusing than high-fusing porcelains when held for a long- time at the maxinmm heat required to fuse theuL 9. Low-fusing porcelains are denser, have greater sliriidv- age, and less Iciisih^ strength than high-fusing porcelains. 10. By rejjeated heating of ])orcelain to the point of high bixMiiliiig, it will finally become fused and maintain its charac- l('ri>!ic coloi". 11. lligh-rusiiig poi'cclaiiis shi-ink from 15 to 25 per cent, whih' low -fusing poi-celains shi-ink from 20 to o5 per cent. There is an ei'i'oi- in the ninth and eleventh deductions which, because of tlicii' unimportance to the student, will not be 1;ik('n up. 1l!. a coarsely gi'ound ])orcelain fuses at a higher tem- jjeiatnrc ;iiid shiink's h'ss than one of the same fornuila finely ground. TIIK I'dltCKLAIiV INLAV . 327 K). The aiiiouiit ol' sliriiika<;(' of any porcelain will in a measure l)e dependent upon the consisteucy to wliicli it is mixcMl and the density to whicli it is condensed; the thin niixtui'e sliowino- more shrinkage tluin tliat of tlie ])utty-like consisteney. 14. Underfused jjorcelain is more o))a(pie. Overfused por- celain becomes lig-liter and tends to heconie more trausparent. Overfused porcelain loses in streu'^tli in ))i()p<»ition as tlie tem- l)erature is increased. 15. The tendency of l)otli lii^li- and io\v-rusin<;' ])orcelain is to assume s]>her()i(lal foiin when overfusiMl, and if considerably overfused they tend to form an ainor])lious mass of fi,lass. Byram quotes tlie follo^\■in,^• advantages for ])()rcelain as a filliuf^' material : 1. Fillin«''s can be inserted much more nearly liarmonious witli the natural teeth. '2. Porcelain is a poor conductor of thermal chan,i;-es and a nonconductor of electricity. 3. The mai-i^'ins of cavities j)ioprrli/ ( t) tilled ^vith p)or- celain are not readily attacked by caries. 4, The cement used as a retainin<:,- medium ^ivinf;- the fill- ing the greatest adhesion of all of the filling nuiterials excex)t cement. T). The jjatient is relieved of sitting with a rubber dam adjusted over the mouth for periods of considerable length and of the pain incident to adjusting the rubber dam and cervical clamps for cavities extending beneath the gum. 6. The nervous strain on both the patient and the dentist is lessened, thereby relieving the patient of the shock whicli usually follows long and tedious oi^erations. 7. If a porcelain tilling is faulty, it is easily displaced, and the patient knows immediately that the sei'vices of a dentist are required. Among the disadvaidages of jiorcelain as a tilling material, he states: 1. The friability of ))orcelain causes it to fracture I'eadily, thereby excluding it from any form of cavity that cannot be so prepared that the overlying margins of the tilling material can be formed or else protected from strain. 2. It is impossible to bevel the cavity sometimes to protect 328 CAST GOLD AXD PORCELAIX IXLAYS tlio cMiamel. Tlie relative stren,<;lli of llie ])()reelaiii and enamel are appri^xiiiiately the sain(\ so that one cannot protect the other. o. It is difheiilt to match tlie c()h)i- of the natural teeth. This ahvays has been and always will he the most serious dis- advantage of porcelain as a hllin<.v material and until we under- stand more thoroughly the general phenomena of color forma- tion, we may exj^ect to l)e disaj^pointed with many of our in- lays. 4. The cement used as a retaining material may cause a change in the color of the tooth or of the inlay. This, however, may he largely overcome by the aj>i3lication of correct prin- ciples in cavity preparation. ."). The cement will dissolve unless there is only a thin film used as a retaining medium. This is not so much a disadvan- tage to the skillful operator, for if the margins are defective he will remove the defect hy making a new inlay; but to the in- competent or careless operator this will always be a disadvan- tage because any cement now produced will dissolve from the margins of an ill-titting inlay. As to the applicability of jjorcelain as a filling material, it will, in my ojiinion, i:>rove confusing to quote Byram on this subject, and it will be best for the student to bear in mind that the writer considers porcelain a]jplicable in simple cavities only, excej)t in the six antei'ior teeth where compound cavities, that, is, cavities involving more than one surface of a tooth, may be filled Avitli this material. No compound cavities in 1)icuspiils or molars should be filled with porcelain. CAVITY PREPARATION The prcparalioii of simple ca\'ilies foi' the rece])ti()n of porcelain inlaxs lias already heen onllined in lliis woi-k. It will, liowever, lie Ix si lo reitei-ate llial llie walls of tliese simple cavities iiiii>1 (|i\-ei-ge so that the lloor of the eaxity shall form \\\\\\ the walls of the ('a\'ily an angle of at least one hundred degre( s. This will insure a more iierl'eet seating ot* the inlay in the cavity than could he ohl.-iined if the walls and (loor of the eaxity forjne(l a right angle. It must he readily ai)parent that TIIK I'OItC'KLAIX 1XI>AV '.l'2[) a j)latimiiii or a ,i;()l(l mat fix occupies some space, and since the ])()i-celaiii must be halted in a mati'ix aiul that mati"ix subse- (|ueiitly sli-ipj)e(l olT the i)()rcehiin iiihiy, some space will be ])i-es( nt between the ca\ity and the inlay, which space is su])se- ((ueidly Idled by cemeid. if then the walls and floor of the cavity are at a i-i.nlit au,i;le to each otliei', tliei'e will be a cement line showinn- all around the inlay. IT, howevei", tlie flooi* and walls of the ca\ity ai-e at an obtuse an,'j,le to eacli other, upon the removal of the ])latinum, the inlay will be allowed to seat itself fui'ther iido tlie cavity and because of its wed^-'e forma- tion (of obtuse an,i;le foi'mat ion ) will nioi'e closely seal tlie cav- ity at its external or iuar,i;iiial surface. This will sometimes entii'ely ()))literate any evidence of cement except that the latter will show under a ma;4iiifyinr>' f^'lass. In ])re])ai'in,i;' coiu])ound cavities in antei"ior teeth for por- celain inlays, we have the same factoi's enterinii,' into the cavity preparation which are present in the preparation of cavities for ft'old iidays; that is: 1. The surgical or o])erative factor which means the actual cutting of tooth structure (including the extirpation of the pulp) and the ])roper tilling and tr( atment of the root canals. 2. The mechanical or formative factor which means that mode of tooth structure cutting which brings it when cut inlo the field of ])hysics, mechanics, geometry, and mathematics. 8. The alterative factor which means the factor tending to ju'oduco a change from decre])it or abnormal to a healthy con- dition l)ecause of its restoration to proper physical relation to the surrounding tissues. In order to present the three factors mentioned, a cavity for the reception of a compound anterior ])orcelain inlay must comply with the following requirements: Tt must offer a series of angles and surfaces best suited to resist stress or tendency to fracture of the tooth. Tt must ])resent margins so ])rej)are(l as to best conserve the enamel structure of the tooth, which in this instance means that the enamel margins must l)e square and not beveled. It must offer a ready access for the making of the matrix or for the taking of the iin])ression, in order to construct a die upon which to swage the matrix. 330 CAST COLD AXD POKCELAIX IXIAYS it iiiust offer a nteiilive i'(H'e])ttU'k' and su])])ort to the iiila\'. It must offer a series of angles aiul surfaces best suited to resist the constant tendency to dislodge the inlay. It must ])reseut margins so j^repared tliat tlie iinished op- eration Avill conform as nearly as possi])le to tlie highest con- ception of beauty of form. It must iDvesent a form for the reception of the inlay which Fi-. ;!()6. sball bi'iiig the \'ai'ious margins iiilo arenas of comi)arati\'e im- munities. P^)!' liic pi'opcr insi niiiM'iits, rcfci' to ("liaplcr \\ l^'ig. S, on cavity |)i-('pai at ion for gold inla_\s, wlicrc also will be found the general rule- for tootli cutting, etc. Dr. I*\ 1'. \'an W'oert, wbo is an ardent ad\ocaie of llie ])oi'- c(dain iiila>' and of the indii'ect method, published a series of 'I'lIK POKCKI-AIX IXI.AV 331 illustratcil articles in lli«' Dciihil llcnis of liilcrcsf. A iiiiiiibcr of illustrations and a description of tliem is liei'e icproduced. Fi^'. 30(5, A, />', (', and I) shows a method of ()l)ta.iniiig a se})- aration hetweeii two teeth which ai'e to he inlayed. A ])iece of li^atiii"e silk is doul)led, and hy means of a floss silk loop, it is <;ui(led throug'li the interdental space below the contact point of the teeth to be separated. A loop is then tied in the li', he illustrates a method of separating, ()!• more oi' less tilting back to normal two teeth which, because of extensive caries, lean toward one another. Jle states: "There are cases wliere extensive caries may have caused FiS- ;!(i7. tlie leaning of two teeth, say a bicuspid and a molar (Fig. 307, A), or two molars necessitating very extensive separation to place them in anything like a normal jiosition. In such cases, I have obtained most satisfactory results by rtmoving the su- ])ei-ficial decay and filling the cavities with Calxine cement (a tem])orary cement), then inserting a small piece of seatangular tent at the point of separation, as shown in Fig. 307, B. "I l)elieve this method was devised ])y Dr. Johnson, of Brooklyn. It would ])e better to experiment with this material l)efore putting it to practical application. It is procurable at most drug stores or at any surgical supply house, and comes in the form of short i)encils in a variety of sizes. The expansion is in its diameter and not in its length." TIkm'c is v(M-y little occasion for the se]iaration of teeth in 332 CAST GOLD AXD POnCELATX IXLAYS gold inlay work, and it sliould ])v used with ^Tcat caution wlien used at all in any kind of work upon tlic teeth. I have seen many cases of malocclusion and subsequent de- struction of teeth and their supporting- and surrounding tissues brought about l)y over enthusiastic separation prior to inser- tion of contour fillings and inlays. These restorations ahvays made the tooth too large mesio- distally, and thus forced all the rest of the teeth in the mouth out of their normal lield of residence and excursion. SeiDaration can be avoided in most instances by gaining free access to the cavity from the occlusal surface and by sane extension into areas of comparative immunity. /Sf '.mii^^^^M F/q.2. In, Fig. 308 Van Woert illustrates the preferi'ed manner of preparation of a simple cavity for a porcelain inlay. For hair of its depth, the cavity ])resents walls ])erpen- diculai- 1o tlic lloor, tlic otlio- hall' of tli<' walls being divergent. When the iiila>' is linislicd, a portion of its inner ])art is ground off to allow of its being seated, so tlial the llaring walls \\ill eoiiie in contact willi llie toolli sli-nctui'c and obliterate as iiiucli as ])Ossiblc the cement line Dr. Schreici', of X'icmia, I'ccoiiiiiiciids the making of the matrix of platinnin l)\- placing llic Foil hctwcMii two layers of goldbeater's skin, 1lin.~- fonniiig a ci-adlc Tor llic foil and ]*e- ducing the chances of breaking thi'ough it in tlie process of swaging. (See Figs. .'JOf), MIO, and lill.) TIIK roltCIM.AlX 1XI>AV 333 A vcTv iliiii i-iil)l)( f (laii! will s('i'\-p (>(nially well as the outci' layer, while a |)iece of lliiii China silk will take the ])la('e of _i;()l( I heater's skin as tlie other pai't. If the iiiali'ix is to he roi-iiied in the iiioutli, the foil is ])larod l)ot\veeii the two layeis ol' sii|)j)()rtin^- material and slij)j)ed between the teMli, the I'uhhei' dam or outer layer hav- ing heen h I't somewhat longer so that the extended lahial and lingual jjortions ol' it may he gi-as])ed with the lingers fii-mly around the tooth ])resenting the cavity. With a ])aii' of Toil carriers, the ends ol' which terminate in a hall, })ieces of s])nid{ or cotton or small chamois disks are Fiff. oUSil. Fie. 311.: now packed carefully, and in sequence, into the cavity covered l)y the three layers of material, that is, the silk, the foil, and the rubber dam. "When the foil has been packed into the cavity as deei^ly as the circumstances will permit, the rub])er dam may be dis- pensed with and the packing of chamois disks is renewed to more closely adapt the foil to the tooth. The packing is again removed and the almost conq^lete matrix is carefully lifted from the goldbeater's skin or China silk, wliich, having served its pur])ose to act as a cradle for the delicate foil, may now als(^ l)e dispensed with. 334 CAST G(H.D AND TOIU'KI.AI X IN LANS Fis:. :n2. / 1:1 Fitr. .';i.3. Fig. ;ji4. Tllli ronCELAlX IXl.AV 335 Fig. 313. Fio. 316. Fio- 317. Fig. 318. CAST (lOLD AXI) POTtCET.AIX IXT.AYS Till' foil is HOW carcrully r( jjlaccd into llic cavity, the labial and lingual sui])lus of it is tackod with sticky wax to the respective surfaces of tlie tootli, tlio clianiois disks, or spunk, or wet cotton in the shape of small halls, are again packed into tlu' matrix and it is thus more and more closely aihipted to the floor and Avails of the cavity. The j)ackiiig is again removed and the marginal adapta- tion may be best comijleted with nonmetallic instruments of glass, celluloid, or agate. The very hard tantalum may l)e used. y\'r. ;n9. Tlie gi'catcsl care should he cxci-ciscd so tlial the iiuirgius i-cnuuii intact and i)resent a smootli unhuckhMl a])])earance. A small cone of inlay wax is sol'ti'iicd in dry heat, and by means of a tliin hioad, ))lastic insti'ument, it is caicl'uIlN' i)acked into the matrix and over the margins of tlie cavity. Tlic tacking of hard wax is now i-cinoxcd IVom the labial and lingual suifaces of tli<' tootli and the Toil liberated. A blast of cold air iijxui llie lootli will cause the matrix to 'I'lIK l'()i;('KI>AIX l.\l,.\V 337 loosen fi'om its scat ami it may he i-cmoNcd rrom llic mouth to bo can-icd into the iiiNcsl iiiciil. 'riic riii'llici' proccdiiic iii\()l\('(l ill the const nid ion of tlic |)()i"cclaiii iiila_\' lias Wccii I'lilly (icscril)C(l in the prcN'ious cha])- tcr on the ,i;()hl iiihi_\' in ccinhlnatioii with silicate and ])()rcc- laiii. I^'i.i;'. 1)12 shows a set of ei,i;lit ,i;lass rurnishei-s used in adapt- ing' a foil mati'ix to the cavit>' in a tooth of in a die. Fi.ii,'. olo shows a set of taiitaluiii insti'umeiits designed foi- this j)ur|)()se. l^'ii;'. .'514 shows a small ])latinum tray made by ])incliin^' the i'our corners of a i'( ctaii^ular piece of ])ert'orated ])latiuuin 30-ft"au,L!,(' tliicl';. This tray may be used as a cai'rier or coutainei- of the iuvestin*;' matei'ial in which the mati'ix is ludd. Dr. Van AVoei't hei-e illustrates (Fifts. 3ir)-318) the mixing of the silver amalgam; (1) the invested imi)ression of the cav- ity; (2) the die into wdiieh the matrix is to be swaged; (o) an in- strument to l)e used as a swager; (4) this instrument consists of a wooden handle which carries a pointed soft rubber cone, (I th;' soft rubber end, h the ferrule of metal, c the screw fasten- ing this to the wood. In Fig. 819 is seen the foil reposing be- tween the layers of goldbeater's skin and the application of the hand swager. The complete adaptation of the matrix to the die may be brougld about in the S. S. AVhite or Ajax swager as elaborated upon in a previous chapter. Figs. o2() to 371 ai"e taken from an article published in the Denial Items of Interest written by Dr. Van \Voert, illustrating a simple way of making trays for carrying compound to take imj^ressions of different types of cavities. Some yeai's ago Dr. Xies, of Brooklyn, read a i)aper which was published in the Dcntdl Items of Iiiferesf. He attem])ted in that pai)er to give to the profession a method of making a porcelain inlay without the use of a metal matrix, thus minimizing to a large extent, the cement line in these restorations. I feel that it will be more just to the doctor to quote his ])a])er minus the introduction, ])ractically in full. ooc CAST COT J) AXD P()r>CET.ATX INLAYS Fig. 321. CL '-^- •'- Fi- 324. Fig. 320. — A flisto-labial cavity in a ccntrfil. Fig. 321. — A strip of jilatinoid l)Ciit at aii oliti'se aiii;l(' and perforated so as to hold the conipouinl which is softened in the tlanio and deposited upon tiie im- provi.scd tray. Fig. 322. — Carrying tray and eoiiijiouinl hetween the teeth and forcing tlio material into the cavity. Fig. 323. — Lingual view showing surplus of compdund at a. This surjilus is removed to facilitate removal of impression. Fig. 324. — Flat .straight spatula to aiil in j)Iacing and holding inijiression mat^'rial. THE POIICELAIX FXLAY F'iii. ;;2s. Fig. 329. Fie-. 330. Fig. 325. — A labio-disto-lingual cavity in a lateral. Fig. 326. — First step in formation of tray. Fig. 327. — Second piece of metal. Fig. 328. — Improvised slide made from metal sjiown in Fig. 327 to fit into that shown in Fig. 326. Fig. 329.— Showing 328 on 326. Fig. 330. — Shows 328 carrying compound and taking impression of lingual part of cavity and all of distal part. When the compound ha.s hardened, all sur- plus is removed from the labial surface and this surface is lubricated. Fig. 331. — Shows 328 carrying compound and sliding down upon 326, when this has hardened, the slide is raised and the impression is removed from the tooth in a lingtial direction. The slide is allowed to descend again until it reaches its destination which is fixed by the compound. This will give an impression of a cavity taking in surfaces of a tooth. 340 CAST GOLD AXD POECELATX T:N"LAYS Fia-. 332. Fio-. 33.- Fig. 334. Fio-. 335. Fig. 33G. Fig. 337. Fis. 338. Fig. 332. — A linguo-niosial cavity in u lateral. Fig. 333.— The tray. Fig. 334. — The impression. yjg_ oo5__rp],g plastic instruments used as an aid to project the compound into the cavity. • t ^, 4.^ ,i Figs. 336, 337, and 338.— Showing cervical cavity in a cuspnl, tlic partly antL completely formed tray. THE roKCKl.AlX JXLAV 341 Fiff. 3:39. Fiff. 340. Fig:. 341. Fig. 342. Fie. 343. Fie. 344. Fig-. 345. Fie. 346. Figs. 339, 340, aiul 341. — Showing a cervical proximal cavity in a lateral and the partly and the completely formed tray for taking impression. Figs. 342, 343, 344, 34.j, and 346. — A cervical cavity in the disto-labial surface of a molar, the partly and the completely formed tray with compound in position on the tiioth and the ini2)i-os^;i()n of the cavity. 342 CAST GOLD AXD rOlUMDLATX INLAYS Fi- ;:47, Fig-. 348. Fit;. 34i). fm% Fig. 3o.3. Fis or traxs. .M>' ol)J( ct in doing awa>' with the ti'ay where possible is that the space it occnpies is ol'teii soi'ely needed to successFull)' w il lidraw the ini|)ression. The wax I have had jji-(^j)ared is tongli, nondastic, and coiiti'acts oidy slightly, which is easily coi-recl<*.\liil)it has kindly been made for nie hy ])r. F. T. Van Woert, of Brooklyn. Some of the brass cups devised by Dr. Price have many excellent features. These I have also mounted for your inspection. The use of modeling comiDounds is not practical with the porcelain matrix, because this matrix material takes time to set and is hardened by heating. Many of the impression compounds, which contain shellac with whiting as a base, swell and form gases when heated, which distort the impression beyond all usefulness before the matrix has had time to set. It shall give you later in my paper, how- ever, a convenient material, which would be ideal could its con- traction be controlled, that can be used with these impression compounds. ''A splendid impression could also be taken with oxyphos- phates. Before inserting cement in the cavity, test withdraw- als should first be made with modeling compound. After all the undercuts shown to be present have been removed or filled with cement, the cavity is jDainted with vaseline oil and the ce- ment pressed into the cavity with instruments dipped in alco- hol. The impression should be withdrawn as soon as it is suf- fteiently hard to handle. An advantage of this material is that it can be fractured for withdrawal and later united l)y addi- tional cement. "AVhere it is possible to take the bite and imiDression to- gether, it is advisable to do so, the wax filling made first and i-enioved adhering to the bite. *'AVe i)roceed in the case of wax impressions with cups to support the frail edges of the inij)ression by embedding it in a plate of softened wax whose melting point is lower than the piece whieh we are investing. This procedure is necessary to ])rev(Mit tliese tiny impressions from being engulfed and dis- aj)]jearing l)elow the surface of the pouring comijosition. AVith a tliermometer as a guide, we i)lace our imjoression next to a stove and heat it almost to the temperature at which it was when we introduced it into the cavit}-. This temperature was determined l)y a bath thermometer innnersed in the same cup with tlic wax. One reading suffices for the whole box of wax. Tlie wax imjjressions need no ticatmcnt. Tlie cement imj^res- sioiis, howevci', are (•over((l wilii a solution of gutta to pi'event Till-; I'ol'.CKl.AlX IXLAV .Sf)! clicmical adioii hctwccii llic iiiali'ix inalcrial and llic iiiijji'cssioii inatci'ial. "We liaNc HOW i-caclicd tlic ])()iiit wlici-c wo abandon the niotallic iiialiix I'oi- llic ])()i'celain matrix. Jt is a ijorcolain matrix l^ecausc the malci-ials that enter into its com])osition are tliose tliat enter into tlic coinposition of jioicclain, namely, sili- cate of alumiiiniii and free aluininnni and lime, which on treat- ment witli phos})horie acitl form ])lios})hate of lime and alum- inum, which <;ive8 this mixture settin*;' qualities. The difference between tliis matrix material and many porcelains is the a1)- sence of the fehlspar and the Huxes, which are incoriDorated in the porcelains to increase their fusibility; for example, such sub- stances as sodium carbonate, potassium carbonate, sodium bo- rate, or glass. These tluxes would be fatal to the jDorcelain matrix, because their presence would cause the aggregates in its composition to vitrify or fuse, thus coat them with an insol- uble glaze, making it very difficult for the deconii)osing mixture to enter the interstices between the atoms of the matrix to dis- integrate it. The phosphate of lime and aluminum, which is slowly soluble in the decomposing mixture, would be protected by the coating, and would not be acted upon, thus making it impossible to free the inlay. "The matrix powdei's are linely ground, separately mixed in the right proportions, and heated to a bright red heat to exi^el all water, both free and combined. The mass is then tinely ground to impalpable powder and is ready for nse hy mixing with dilnte glacial phosphoric acid. "I found this material so difficnlt to proj^erly prepare, with- out adequate laboratory facilities, that it has been necessary for me to secure the services of a chemist. "AVe are now prepared to pour our matrix. On a glass five by tive we place onr materials, mixing thoroughly with hone, glass, or gold spatula, to a thick workable consistency. AVith a tiny brush we ])ick up this mixture and paint our impression with it, adding thereto until the impression is coated. Xow thicken the mixture and till in the impression with a thicker mix. Wrai) the impression in bibulous pajDer and gently press the mixture against the impression. Leave it in this condition for a few hours to set, after which place it near a source of O0_ CAST COLD VXD PORCELAIN IXLAYS heat of some kind and allow it to dry for a few hours longer. Li the drying the advantage of having a wax that fuses at high temi^erature is apjjarent, for it is possible to use a greater heat in drying, hence the better adhesion of the material. Now l)lace the i^oured imi:)ression in or on a stove and gradually lieat it, to burn ujj the wax, continuing this heat until the model is hard. The matrix is allowed to cool, and if too thick is ground down on a carborundum stone. By grinding the matrix as thin as possible the decomposing mixture has less material to penetrate when freeing the inlay; the thinner it is, the more quickly the heat penetrates the matrix and fuses the l)orcelain. In low-fusing j)orcelains the grinding has the ad- ilitional advantage of so 23ermitting us to form the base that we can direct our porcelains to flow where we wish. "AVlien the mold is cold, we carefully ipmiit the outer sur- face with a fine camel's-hair brush right up to the marginal edges of the cavity with a solution of gutta, which I have pre- pared for the i^urpose of varnishing teeth to protect them from the destructive action caused by the wearing of regulating ap- pliances. This solution I have adapted to the additional pur- pose of varnishing my matrix. It is made from ))alata gum, from which the resins have been extracted by the usual wash roll jjrocess. It is then dissolved in bisulphide of carbon, washed in acetone, filtered and redissolved in chloroform. This makes a pure solution of gutta, with more body and tougher than before obtainable. This gutta has the valuable faculty of swell- ing under heat, and if wlion filling your matrix any unfused porcelain should hajipen to accidentally extend l)eyond your cav- ity margins, the swelling gutta largely dislodges the superfluous porcelain and prevents its adhesion to the outside of the mold. Great care should be exercised to ])re^'ent this. After each bak- ing tlie outei- siii'face of llic mold is rex'arnished. "We now ])re2:)are to lili llic inatiix with porcelain. There are Tiuiiiei'ous ways of doing liiis, and every man prefers his own, l)iit in this pi'ocess it is iiecessai-y that the first layer in dii-cf't ('(iiitact with tlic inati'ix he lirsl I'liscd oi' gla/cd, "it is higldy iiiij)oi-taiit with the ])orc('hiiii mali-ix that the mold be heated gradually and thoroughly, 'i'lic poi-cclain should be fused bv receiving its heat IVoni contact witii the walls of THE poih;klaix ixlav 353 llic iiiati'ix I'ntlicr lliaii IVoiii direct rui-iiacc licat exerted on tlie ])oi'('elaiii itself. If tlie mold lias been iin])roporly heated the tendency of the porcehiin is to hall iij) and lea\'e the cavity margins, making' it necessary to fill in between the inlay and matrix — a tiling- whicli we sliould seek to avoid. Tf tlie mold is ])ro])erly heated, the tendency of the ])orcelain is to cling to it and t'orni a ])ert'ect ada])tati()n to the cavity surfaces. To bring al)out this result a clay hood to cover the matrix while baking is ahsolutely necessary, for it prevents direct action on the i3orcelain and enables us to hold back the fusing of the porcelain until the matrix is properly heated. In large con- tours or long cavities a thin film of baked porcelain sliould first cover the model; then cervical and incisal ends are filled and , baked, the intervening space being filled later. Filled in this way, I have found that the porcelain does not shrink away from the interior surface of the mold, Init on the contrary clings to the same tenaciously, so that if any shrinkage takes j^lace, it is not at the point Avliere the inlay contacts with the walls of the cavity, but is in the interior, which is later filled in and the piece baked. As it is gradually heated so it is gradually cooled. Additional jiorcelain is now added Avitli brush and spatula, pressing and forming it Avith fingers and bibulous paper. The addition of gum tragacanth, mixed in the water used to wet the porcelain, is a great help with some high- and medium-fusing bodies. I recommend that medium fusing porcelain be used, because there is no liability of checking from contraction with these bodies, while with low-fusing porcelains there is, unless the cavity is almost filled with quartz. This trouble with low fusing bodies seriously threatened the success of my work until I substituted medium- and high-fusing porcelains. The fact that cracks do not occur with low-fusing jiorcelains when baked in a metallic matrix is proof that the matrix yielded and was distorted as the porcelain contracted. Did the walls of the me- tallic matrix hold firm, cracks would also be common in this type of inlay. High-fusing porcelains contain a high percentage of silex and kaolin. Both of these materials are virtually con- stant, adding compression, strength, and stability. The high- fusing porcelains having far less contraction than the low-fusing porcelains, it must follow that the men who have been woi'king 354 (.'AST COLD AXi) POIH'KI.AIX IXLAVS \\\{\\ till' liii;li-riisiii,u' |)()rc'( laiiis ]\i\\v iiiadi' more iieai'ly perl'ect Uttiiig inlays, for tlicre lias been less shrinkage to their material, and consequently less distortion to tlieir matrices. *'Tlie ])ieee liavinii,' heen re])eatedly carried to a high bis- cuit iov contraction — and there are men who claim it must be carried to a glaze to secure maxinumi shrinkage — allowance should be made for the lightening of the selected shade by the re])eated tirings, and a porcelain should be chosen a few shades darker than the tooth. Tliis rule holds with labial cavities, but should not be ajjplied to api:>roximal cavities, where the shade should never be dai-ker than the tooth in the mouth, because when exactly matched in this location it looms darker than the tooth. It should l)e a tritle lighter. "Shaping and contouring should now be done, and there is no safer means than the carborundum disk, grade No. 00. It cuts cleanly and smoothly, and will not chip the inlay. Ruby, garnet, emery, or sand disks should be used in inlay work. If in the final fusing it is not the exact shade you seek, the glaze may be ground off with the same carborundum disk, No. 00, and a better shade of ])orcelain applied and fused. The inlay can also be removed fi-om the matrix, tried in the mouth, rein- vested and finally glazed. But tliis takes time. As no porce- lains have a definite fusing point, they should be gradually heated. Tlie tliorougli heating of the mold should always be done before the point of high biscuit is reached. ''Earlier in my ])ap(M- I ])romised to give j^ou a material that can be used as a matrix mold, to pour into modeling com- pound iin])ressions, to forin matrix molds to be used with low- fusing porcelains. This material is no other than the oxyj^hos- pliate of cement that we have had on our shelves the greater pai't of oni- lives, it is mixed in the usual way and woi'ked into the compound impression, covcrccl with bibulous ])a])er and pressed home Al'tci- setting It is slowly di-ied over a Bunsen bui'ner and is i-ead>' I'oi- use. The melting ])oint of this oxy- phos])hate is a little ovei- 1,700 F., var>'ing slightly with the dif- ferent cements. As low-rnsing poi-celains have no fixed melt^ ing jtoint, by slowly heating tlie\- can be glazed at about 1,600° F., according to my ])yi-()meter. The compound impression should !)(' expanded betoi-e using to connteract the sliriidrate my mold. I found tliat a solution of one part hydro- chloric acid to four of water is exceedingly effective, cheaper, simpler, and less dangerous than any of the others. We now ])lace the inlay, coated witli wax or gutta, in a bottle of cold dilute hydrochloric acid, leaving it when possible over night, if you are i)ressed for time, the separating process can l)e has- teiK (1 by heating, which will cause disintegration of the mohl in a short time. A chimney should be used to carry off the fnmes. Even Avith this weak solution of hydrochloric acid, it is imi)ortant that the inlay be covered with melted wax or the gutta solution before innnersing it, otherwise it will be found that this weak solution has acted on the porcelain and desti'oyed its luster.* "The inlay is now cleaned with small l)urrs, and brushes dipped in a solution of Bonsit to remove any trace of foreign material from its surface. The inlay is now ready to set." The process of casting porcelain in a vacuum machine was successfully accomplished by Dr. F. S. AVelden. In this process, the restoration is lirst made in wax, just as in the cast gold inlay; this wax inlay is then invested in a clear white refractory compound, the wax is burned out and the porcelain fused in the crucible of the flask; when the mass is liquid, the valve is opened and the porcelain is sucked into the mold. It is ad- visable to keep playing the flame upon the soft mass to better fill the entire mold. The process never became popular and is now i3ractically obsolete. Further elaboration of this method may be found in September, 1911, issue of the Dental Items of Interest. Dr. Stanly Towie, of Fall Eiver, Mass., takes an impression of the cavity for which he is to make a porcelain. He varnishes this impression and then runs a model in inlay wax. He next suspends this model in hydrochloric acid (it seems to the author that hydrofluoric acid should be used) and dissolves the cement. The wax model is now cast in pure gold. He thus gets a re- production of the cavity in pure gold in which he now bakes his inlav. *I can not conceive any advantage in casting the inlay witli wax or a solution of gutta if we are going to subject the acid medium to heat. 358 CAST (!()LD AXl) POllCEl.AlX IXLAYS Tlioiv are some a(lvaiita<;es and mmierous disadvantages in this method. Idie advantages are the j^erfect unswaged matrix, tlie practically obliterated cement line, the ease with which the matrix may be handled withont distorting it, and the conven- ience of tlie patient. The disadvantages may he enumerated as follows: The frec{uent checking of the porcelain whicli comes from the ditt'erent coefficient of expansion and contraction existing between gold and ])orcelain. The difficulty of seating the inlay when completed, whicli may l)e obviated by grinding that jjart of the inlay whicli enters the cavity first, but Avhich at hest is an empirical procedure. The necessity for chemically removing the matrix, which proc- ess consumes a great deal of time and involves the handlmg of powerful acids, the fumes of which are very unpleasant, and hnally that the method entails a sacrifice of time which is not justified, at least in my opinion, hy the results ol)tained, the latter not heing sufficiently superior to those ohtained by the use of a very thin matrix material such as 1/2,500 foil of plat- inum. For further and more comprehensive elucidation of the porcelain prol^lems that the practitioner may have to face, I am pleased to refer to Byram's "Principles and Practice of Filling Teeth with Porcelain," adding only my own chapter on the coloring prol)lem of this phase of our work. ciiArrKii xxji EX1)()C'1UX()]X)NT1A, OR THE DlK^rLESS GLAXDS— TUKWl EXPIJESSIOX IX THE IITMAX AIOETII Tliore are many ])L'()])1(' who are perl'eetly well; their daily life is often one of intense })liysieal and mental activity, and yet tliey rarely, if ever, require therapeutics or mechanical atten- tion. There are others who are miserably ill, mentally and ])liys- .ically, tluMr daily life is one of continued attemi)t to ^iiai-d against further encroachmtnt by disease. They are continually under the care of some one ministering- to some of their ailments successfully or otherwise. Some people for a period of time are perfectly well, then, for some obscure, and to most observers, unaccountable, reason, sicken or fall seriously ill, to recover in the same obscure and unaccountable manner and continue to live and to work without furthei- interference from disease, for theii- allotted numbers of years. in corollary with the al)ove, there are many people whose dental apparatus is in perfect balance, mechanically expressed, in perfect occlusion, who never recpiire any (h^utal interference; still others whose teeth were in imperfect condition, as expressed in nudocclusion, have had them jDlaced in balance, and subse- quently require an incessant amount of dental interference to keep on repairing and replacing jKirts of the continually break- ing down apparatus. Some people never jDay any attention to the cleanliness or the environment of their teeth, and yet they never need to, nor do they seek dental interference for the alle- viation of any dental disorder. There are others who are con- stantly having their teeth cleaned, their roots scraped and their gums scoured, and still their teeth continue to ])resent new cavi- ties, new breakdowns, new dystroj^hies. Manifestly, the correction of bodil_\- health and toolli health is not clearly understood. ^[any physicians, numy surgeons, many dentists will readily 359 360 CAST COLD AXD PORCELAIX IXLAYS admit the truth of the fore^'oino- and attest to the statement tliat tliey are and have been constantly on tlic alci't for some thing, some truth, tlie understanding of wliich woukl enable them to more effectively handle and efface bodily disorders. ]\iay it not justly be said, right here, that the cause of med- ical and dental ineffective ministrations has been due to the classification of cases of patients in the aggregate under the heading of certain diseases, when we should have devoted our attention to the close study of the individual constitution of each patient, and so learn to treat an aggregate malady in an individualized way. It is a fact that the same disease will express itself differ- ently in different individuals, and yet, if we take np our works on therapeutics, we shall find a woeful lack of individualization of cases calling for treatment. Under the heading of "Pneumonia," the pneumonia is treated, under the heading of "Diphtheria," antitoxin is advo- cated. Tuberculosis has its prescribed order of treatment, etc. Tt is always the disease, almost never the patient. AVe have become so ol)sessed with the pathologic anatomy of the case that we fail to recognize the ever receding voice of God in the individual, struggling with all the normal that is in him, to overcome the very joicture we take as a guide to our treatment. It is so in dentistry, we see the teeth of children decay, and we either remove the teeth and disturb the arch ; or we fill the teeth which have decayed, and allow the child to go with the predisposition to decay in the constitution, unrestricted to work its further havoc. AVe see a case of so-called ti'aumatic occlusion and we begin to file and grind the teeth into iiioi-e or less acceptable stress relationsliip, pa\ing no attciiiioii to the ])articular "ism" in that particulai- constitution which caused the arrangement of teeth ultimately bi-inging about the traumaism that sent the patient to us in seaich foi- relief. A woman becomes ])i-egnaii1, beai's and gives birth to a child, many of her teeth begin to decay, she loses one or two of them, dui'ing the period of lactation, she seeks our advice and hel]), and we dentists, i)i almost evei-y instance, fill the decayed EXDOCIMXOLHjNTlA 361 t(H'tIi and rt'j)lace the lost oiios and dismiss lici- to fto tlirou^li the same dental ordeal, should she l)e called upon, in her relation as a wife, to again become procreatively active. A case of pyorrliea presenting for relief, tlie patient is either pyroeided, vaccinated, scaled, scraped, scalded, rubbed and drugged locally, a few teeth are lost, being too far gone; a few are filled, not far enough gone; a few are crowned with golden caskets and the bill paid, the patient is allowed to go and take the pyorrheal potential in his or her constitution, the attack recurs with renewed virulence and renewed destruction. Time to change about it seems to me, time to realize that we have not been dealing with the fundamental facts of the cases in our treatment of diseases. All the bacteriology we know has not enabled us to eliminate effectively diseases the bacteria of which we know best and are most familiar with. Time to realize and to profit from tliis realization that there are, for example, any number of individuals to whom we could feed sandwiches made up of bread and pneumoeocci and who would be none the worse for the diet. This is equally true of all germs, not excepting the most virulent of streptococci. Some people's teeth will not decay in spite of the lack of any attention on their j^art or the dentist's part. Some people need but the least exposure to contract all sorts of diseases. Some j^eople's teeth decay in spite of all attention. Some children never have any infectious diseases, some have all sorts of afflictions. AVonderful resistance in the apparently immune specimens, lowered resistance in the others. Yes, my friends, but what is this resistance ! AVhy are some possessed of it and wliy not the others f AVhei-e do they who have it get it, and what do those who suffer lack, in order to make it? Patients have become habituated to seek a physician so he may see the disease. Physicians should become liabituated so that when they look at and for a disease they should see the patient. Patients have become habituated to go to the dentist so he may look at and after the teeth. oG2 CAST t;OLn AND PORCELAIN IXI.AYS Dentists slioiikl ])ec'oino lial)ituated so tliat wlionever they look at a tooth (kn-ayed or liealthy, they shoukl see the patient. All this does not mean revolution, neither does it mean a reactionary j^rogram, it simply means a broadening of our vision, a more comjorehensive understanding, and hence a more effective service in onr field of endeavor. The endocrines are the organs of inteiiial secretion. Endocrinology is the study of the organs of internal secre- tions and the study of the functions of these organs. Secretion is a specialized function of certain glands made up of highly specialized epithelial cells (secreting cells) in the exercise of which function, they take up substances from the blood stream and elaborate these substances into products wholly at variance in aiDpearance and effect with the substances which were taken u]), and discharge these products l)y the avenue of special channels or ducts into various organs of the vegetable, animal, or human economy, to effect the jjliysiologic expression of these organs. Internal secretion may be defined in the same terms, except that there are no special channels or ducts through which the products elaborated by the ductless glands are conveyed to the various organs; so that these products may be said to find their way into the various parts of the body by dii-ectly entering the 1)1 ood stream. The products of the ductless glands or glands of internal secretion have been termed hormones from the Creek word, to excite. Tlieir iiiduciicc upon the functions of the various organs of tlic hody is one of augnieiitation or excitation and, uinkM- some cii'cunistances, one of iiiliibilioii. The potency of these prtxhicts is prad icallx' in(h'])en(h'id of (puuititx" and wholly inlcnlcixMidcid a> to (pialitv. in this re- spect, the>' ai'c \cr\' much akin, if nol wliollx' like enzymes or fei-ments. Tliey ai'c in such a fine slal<' of sul)di\ision Hint lliey uia\' be liixcned to eh'cl ronlomic mcsscngci's comnniuicat ing and cai'rying oi'(h'i"s or dircflions or aid from llic \'egetative centers to all parts of tlu,' body willi which Ihc}' communicate at all. KX]i()C'i;i.\()I)()XTIA o()o T]\(' iiiosi iiiipoi'taiit (hictlcss (glands as we know tlioiii arc, lirst llic ])iii('al, a small ,<;laii(l siiuati'd at tJic base ol' the ])itiutary body. Second, the piluitai-y body, a vei-y vascuhir <;land, consist- ing- of an ant(M-ioi-, middle and j)ost<'i-ioi' ])ortion, all sitiiat(Ml in the sella turcica of the sphenoid bone. It ft'overiis periodicity, I'hythm, inlluences i;rowt]i, nutrition, rei)roductioii, the psy- chosis, and is influenced by the thymus, the thyi'oid, the <;-onads, and the adrenals. Third, the thyroid ,<;iand and the ])arathyroid Ijodies. The first consists of two lateral lobes, disjjosed on either side and in front of the larynx and ui:)per three or four rings of the trachea. The parathyroid bodies are arranged on either side of the me- dian line and niav he found as low as the seventh tracheal ring. The thyroid is a very vascular hody of gland tissue, it is sup- plied l)y the su])erior and inferior thyroidal arteries, which form a rich anastomosis. The veins are correspondingly free and numerous, they are valveless and empty into the jugular and innominate veins. It inHuences nutrition, growth, rej^roduction and is profoundly influenced l)y functional and organic disturh- ances of the alimentary canal and the gonads. Fourth, the thymus develops as a paired sac-like divertic- ulum of the ventral ])ortion of the third and fourth and possibly the second pharyngeal cleft. This sac-like heginning of the thy- mus is entirely epithelial in structure. It influences metabolism in the child, also the thyroid, the pituitary and the gonads, and is itself markedly affected l)y pituitary and adrenal disturhances. Fifth, the su])rarenal capsules, adrenal hodies, are two small, flattened, glandular bodies located in the l)ack part of the al)domen, above and somewhat anteriorly to the u])per part of each kidney. They consist of a cortical and medullary portion, they are exceedingly vascular, with abundant lymph supj^ly. The nerve supply is significant, l)eing derived from the solar and renal plexuses and getting branches from the phrenic and j^nen- mogastric nerves. Their im])ortant connection with the sympa- thetic is today well known. Dr. Jose])!! Fraenkel terms the symjiathetic nerve "the frozen adrenal" attempting to convey the im])ression that it is a continuous line, icicle as it were, of 3G-J: CAST CJOLD AND POllCELAlX l^^LAYS j)n)j('cU'(l adii'iml substanco. Tlie adrenals play a most imj)ort- aiit ])art in the development of the being; a tremendous part in the mental growth of the being. Virtnally, the great center of the autonomic nervous system, they have been called the abdom- inal brain, they control energy and the decorative scheme in the body; tliey lia\e everything to do with pigmentation, with oxy- genation of the blood; they influence the thymus, the thja-oid, the pituitai-y body and the sexual organs, and are themselves mark- edly affected by thyroidal, pituitary, and gonadial influences. Sixth, the gonads, the organs of immortality on the pro- creative i^lane or better, the instruments whereby man perpetu- ates his species on earth. In children the gonads are markedly influenced by the thynuis, the persistency of which will retard adolescence. In children of normal development, the thymus goes out at puberty and the thyroid Avith its regulating and supervising influence comes in. At that time also, the assertive ])eriod of tiie gonads becoming manifest, they call on the adren- als in the male and on the pituitary in the female to set up an intercommunicating system of harmonic relations, which result in a most intimate interdependence, very apparent in the female during menstruation, pregnancy, childbirth, and lactation, in tlie male during periods of great physical stress, excitation or copulation or of sublimation of the j^rocreative urge into intel- lectual or intuitional poetic expression, in other words during inversion of procreation to creation. The foregoing may be summed up rather crudely as follows: Th y 1 1 1 us — Youth. Thyi'oid — Quality and equilibrium. I^ituitary — Bulk and disposition (psychosis). Adrenal — Energy and decoration. (lonads — Immortality or ])rocreation. Pineal — Intelligence, soul oi- cosmic relationship (?). Tlie normal, augmented or inhibited activity of one or more oi- iiU of these glands is manifested in diverse ways in the human, dental apparatus, and it is to the recognition and the study of tliesc inanircstations, that I lia\-(' given Hie name of Endocrino- dontia. The thymol rop, the 1ii>i-()1 roj), the pil uilolrop, the adi'eno- E X I )()(' I ; I x () I )( ) x T I A 365 trop and llic ^'onadolroj) arc iiaiiics or dcsLguatioiis apiicnded to individuals who exliihit in tlu'ir makeup, a preponderance of thymic, lliyroidal, ])itiiilary, adiciial, oi' ft'onadial influences, as the case may be. Dr. D. M. Kaphui, the director of tlic lal)oratories at the Neurological Institute of New York, ])ul)lislic(l an article in Endocrinologii, April, lf)17. lie called this ai'ticlc '^An Endo- crine Interpretation of the Dental Ajjparatus." The quotation of tiiis article in full will l)e illuminating-, particularly since I wish to j^oint out what appear to me to ]je some slight errors in his conception and nomenclature. ^' There is not the least doubt that the glands producing internal secretions exert an influence upon the exterior of the individual. Although the uninitiated still may consider cer- tain individual peculiarites as accidental, the endocrinologist knows which organ, or organs, were instrumental in the produc- tion of these seemingly accidental phenomena. To ascri])e a certain bodily appearance to accident is a confession of igno- rance, which, however, is becoming less frequent the more one studies the mystic forces of the endocrines. The study of their functions can not be severed from the study of these glands, so much so, that one may justly call this specialty an investigation of the 'compensatory dynamics of the endocrines in health and disease.' "To understand the compensatory workings of the endo- crines is to know 'internal secretions'; and to be able to trans- late it into terms of physiology and pathology is to know how to handle your patient from an endocrine point of view. There are many external manifestations resulting from the work of the endocrines that have been carefully studied, many that are only superficially known, and still more to be discovered in the future. To the endocrinologist a pigmented mole is not an acci- dent, nor the nmstached female of twenty-five, nor the soft pulse at eighty, nor the high blood pressure at thirty, nor the enlarged, noninfected tonsil. It is the why and wherefore of a peculiarity that is tlie constant question l)efore the endocrinologist, and 3()G CAST c:()Ll) AXD roiU'KLAIX IXr.AVS V(.'ry often tlir answer is ratlieally o])i)()se(l to ortliodox allopatliie tliouglit. Tlierefore the uninitiated may l)e perplexed by the stand taken by tlie student of compensatory dynamics, who ari;nes against tlie reduction of a liigh l)lood pressure in a cer- tain patient, or the removal of the tonsils in another, and yet he may offer very sound reasons for both conclusions. ''In Ills endeavor to arrive at the truth, tlie student of 'com- pensatory dynamics' takes into consideration the fact that cer- tain infections have an affinity or, as I have designated it, a 'tropisnr for certain glands with internal secretion. For in- stance, it is known to all that munii^s is an infectious disease that often attacks the gonads. It has been noted that diphtheria and typhoid have a tendency to crij)ple the adrenals, so that mumps is known as a gonadotropic infectious disease, while diphtheria is an adrenotropic. ''There is also a definite tropism between endocrine disturb- ances and the dental apparatus. Ewan Waller, of Birmingham, England, has very definitely associated the teeth in children with the thyroid function. It seems that the glands with inter- nal secretions play an important role not only in the structural, but also in the physiochemical economy of the individual. A great number of the unclassified subjective disturbances for- merly designated as neurasthenia, neurosis, or hysteria, and lately as vagotonia, can be more justly ascribed to an aberration or a disturbance in the compensatory dynamics of the endo- crines. The thorough investigator of the constitution of an individual in health or disease takes into account the j^henomena not only as pictured in our l)ooks on diagnosis, l)ut also the time of day or night, the amelioration or intensification of symptoms in the evening, its involvement of the right or left side of the body and 1h' (linVi-ciitiatcs where the same complaint a])pears in the juvenile, adult, or senile individual. "There are a great many points dismissed l)y the uninitiated as insignificant, which the endocrinologist employs to advantage ill liiiilding up a picture oF (llslurhcd ('<|iillll)rliiiii in a ])atient. The jK'Culiarilies of the dental a])])ai'atus is one of them. "TffviJODONTiA. — It is a faii'ly well-established fact that the calcium metal)olism is goveiiKMJ chielly by the thyroid ap- KXDOCKI XoDO.VriA ,')()7 l)arcitiis, and sccondaiily, hy the i-csl ol' llic ciKloci-iiics. The alkaliiiily of tlic salixa to a cciiaiii cxlciil dcix-nds ii|)()ii calciiiin salts. It is to !)(' seen liow a dist iii-hcd ciidoci-iiic ('(juilihi'iuiii could ))i-iii^' al)out dental ' l)\' a distui-bancc in tli(» calciiiiii iiietabolisiii halaiicc, ])art iculai'ly in childi-cn \vli() dcjK'nd ii])on their tlixi'oid and thymus more than the adult and senile. The calciuiu bein^' delieienl, tlie acids from food docoiuposition aro not neutralized, and the dentine consequently suffei's, this hein;;- one of the stafi,'es in the coni])lete ])r(.akin;^' down of the tooth. In children ])articulai'ly, a \vell-l>alaiiced thyroid and sound teeth fto together, if the thyi'oid is not perforin ing its duties ])rop- erly, the tooth to suffei- fii-st is the iiiolar. The suhniaxillary saliva is said to he richer in calcium than the parotid, and in view of the fact that the molai's lie Ixdiind the duct, their sui)i)ly of innnunizing saliva is less than the fi-ont teeth, and hence, in case of calcium deficiency, they succumb first. This is mani- festly apparent in the longer life of the lower front teeth as compared with the u])i)er, the latter not having the constant salivary l)atli enjoyed by the lower teeth. This is very charac- teristically disi)layed by the woman with an exhausted thyroid, due to repeated ])regnancies, who invariably loses her upper incisors. Of course in such women the other endocrines enter into the mechanism conducive to dental loss. "To start with, thyroid teeth are distinguished by their slender frame, they are thinner, more transparent, and graceful, and their color tends toward a bluish gray Avhite. Children and married women with such teeth can be saved a great deal of dental trouble by the discreet and timely administration of thyroid extract. The frecpiency of the therapeutic display de- pends entirely u])on the case and the acumen of the physician. "In the multi])ara the dental situation from an endocrine point of view is only partly thyroidal. The interj^lay and com- pensatory work of all of them are necessary to help her through this physiologic symbiosis. If the woman is deficient in any of the endocrines, she will display not only dental changes, l)ut all kinds of other objective and subjective manifestations depend- ing upon the glands or gland involved. The falling out of the upper incisors independent of decay, l)ears a distinct jDituitary stamp, and one may say that the maxillaiy sockets become too 368 CAST GOLD AND PORCELAIN INLAYS large in some pregnant women, and that the root is not firmly implanted in such a jaw, at this episode of partial transient jjhysiologic acromegaly. It is the duty of the discerning jjhysi- cian, as well as the dentist, to guard against irreparable loss, disfigurement and suffering of patients by a timely use of thy- roid extract in cases of dental caries or late eruption, as well as in gestations that ju'omise injury to the teeth. ' ' PiTUiTODONTiA. — Many individuals who are free from complaints that would compel them to seek a jDh^^sician 's advice, are the possessors of teeth characteristic of the acromegalic. The owners of such teeth need not develop acromegaly, never- theless they must be regarded as potentially pituitary. Chronic frontal headaches and the slightest limitation in the temporal visual fields, require very earnest attention and extremely judi- cious endocrine therapy, for at such a stage one might hold out some hope of deferring the advent of the full-fledged acromegalic picture. Increase in size of the acral parts is the chief objective sign of this disease and the pituitary is the gland responsible for its appearance. "It must not be forgotten, however, that not only an in- crease, but also a very marked diminution in size, belong to the activity of the pituitary gland; so that giant and pigmy are endocrinologically related. The same applies to the teeth. The average pituitary dental arrangement shows large square teeth ; oftener than not the upper middle incisors are spaced (trema) and the rest of tlie teeth may share in their separation, stopping at the bicuspids. On the other hand, marked overcrowding is a feature wdiich also belongs to the department of hypophysial activity, so that one is fi-equently confronted with a situation j(M|uiiing gerat care in endocrine interpretation. The gestating female has been referred to before, ])ut it must be reiterated, that the falling out of the incisors, particularly the lateral one, lias a double meaning. At present let us not forget that the middle upper incisors are preeminently the teeth closely asso- ciated with direct j)rimary pituitary function. This does not signify tiiat the individual has a pituitary aljiiormality incom- pati))l(! with perfect liealth; it may show itself in anyl)ody witli EXDOCRIXODOXTIA 369 acceptocl ]iy})0})]iysial iiiarkin<;s, sucli as l)eiii<>' very tall or very short, liaviii<;- a very lai'^e liead, ])ai'ti('iilarly in tlie frontal part, oi" iiiaiiifestiii^- a tendency to adiposity in tlie yonn<;' or adult, with or without hyj)o^enitalisni. It may aeeonipany the fem- inine type of man who shows his abnormality in his teeth only, and his sexual anomaly in his psyejioanaiysis. "(lOXAUonoxTiA. — Individuals with a ,i;'()nadoti'()j)ism may ^ive in tlieii' liistoi'y an attack of nuimi)s during- ciiiklhood. Close relationshij) between this contagious disease and the gen- ital glands is established by the frequent involvement of the ovary or testis in a comj^licating inllannnatory reaction. It is not necessary that the individual previously having had nmmps should present earmarks of a definite gonad disease, he may yet show them in the future or not at all. This depends entirely ui)on the compensatory work of the rest of the endocrines. ''In all endocrine manifestations not oidy the soma, but also the psyche is influenced. Besides these psychic attributes most of them show definite somatic stigmata, of course not all of them, the exceptions here as elsewhere serving to establish the rule, "In the gonadotrojiic individual the dental apparatus car- ries a very striking earmark of the tropism. If the middle upj^er incisors carry a message from the pituitary, the lateral upper incisors certaiidy do the same from the gonads. So that when the gonads are teratologically ah ovo definitely abnoniial, one is sure to find some abnormality in the upi^er lateral incisors. The relationship, if any, is a crossed one, so that the right ujoper lateral incisor may point to the left testis or ovary, and vice versa. "It is also to be noted that the greater the deviations from normal, the more definite the markings in the dental department, so much so, that the lateral incisors, as a result of a marked gonad defect, may not have eruj^ted at all. Such a dental situa- tion is rare indeed, so is also the clinical condition presented by the patient who has it. Here is a situation that the gynecologist could profit by, and the surgeon add another sign to the sig- nificance of right-sided abdominal pain. Such a pain is usually ovarian, when the left upper lateral incisor is faultily implanted. 370 CAST GOLD AND PORCELAIN INLAYS showing- the mesial edge of the tooth anteriorly, and protruding in front of the middle incisor. The teeth j^resumed to be con- nected with the gonads (upper lateral incisors) carry the stamp of ovarian or testicular abnormality in their size, shape or im- ])lantation. "The ovary should always be suspected where pelvic pain is manifested in a patient whose lateral incisors are abnormal. In the male, snuUl stumjiy laterals besj)eak sexual impotence on a i)hysical ])asis, many gonorrheas, prostatic insufficiency, and chronic strictures. In such an individual one may obtain the history of mumj^s, and if he had a rights! ded orchitis or epididy- mitis, more often than not his left upi^er lateral incisor will be differing from the normal, taking his entire dental apparatus on the standard of comiDarison. "On rare occasions the compensatory work of the other endocrines is so well adjusted that the dental anomaly is obliter- ated, and gives no clue to the existing gonadopathy. There are, however, other external signs from an endocrine point of view that would direct attention to the existing state of affairs. As the dental apparatus is the subject of this paper, the other signs will not be discussed. "There is a dangerous tendency among endocrinologists to ' do not conic up 1o llic pliN'siologic requirement, he this in 1lic Form oF under- or ovei-activity, the adrenals are then callc(l upon For additional assistance, resulting, secondarily only, in manifestations ajipearing on the skin, mucous mem- ])ranes, haii", etc. The primary, ah oro. situation can be read from the teeth and the gland res))onsil)le For the trouble more often than not, can l)e uneri'ingly named and proper therapy sug- KXDOCItlXOItOX'l'IA .")( 1 geslecl. II is rciiiai'kahlc liow i-cndily tlic |)ati('nt i-csjjoikIs wlieii tho projxT (Ivuii; is ))r('S('ril)('(l, hiil Ik I'c, as clscwlu'i-c, the futility of atl('iii])liii,i;' i-('|)la('('iii('iit 1 licfap)' in some cases must ])e tliorou^lily ^auftcd. "A youii^' woman sulTe]-iu', and position of llic lectli and their envi- ronment. The Creative Force at Work In llic ac('()nipan\iiig diagram (i^'ig. .'572) two ti'iangles are seen suj)ej"imj)os('d one npon the oliu'i-, making a six-pointed star — the Protector of l)a\id. It i-('j)i-esents the conception I KX!)()("i;i XODOXTIA .179 ]ia\(' of the I'liixci'sal Spirit or AJiiid oi' Soul working- iij)oii itself and L'X])aii(liii^' in coiisciousiicss IVoiii witliin oiit\vai"(l, so that it l)(',<;iiis to manifest itscll:' in various ways on (liilerent planes (creation). The i'aet that tlies(» ti'iang'les are so ])laeed tliat one pre- sents with its apex (h)\vn\vai'd and the otlier with the ajx'x u])- ward, will mean nmcli to tliose wlio liavo studied occultism and ai'e raniiliai' with the litei'atui'e on svmholism. AVe see here the lari2,e ^1 in the center of the illustration. In tlie apicari)ortion of the A we see an S to represent the Sun, the energizer, the father, lie, who with his warmth, animates the Universe. Dii-ectly above, we see the point of the star marked PP representing the pituitary beneath which rests the pineal. AVithin this point of the star, the M repi-esents the Moon with its i^sychic significance to man. obU CAST GOLD AXl) POIICELAIX IXLAYS Till' point on the uppiT left marked T represents the thy- roid and the R within it stands for the restless, ever-moving atmosphere. The point on the rig-lit, also marked T represents the thy- mus or youth or beginning of man. The V within this point represents the vegetable kingdom, even as the R in the opposite point represents the mineral kingdom ^^ ith its finely-divided silicious and other mineral iDarticles floating in the ether. This V representing the flowers and trees and leaves upon the trees is symbolic of ever-recurring youth. The two points below, the right and left A represent the adrenal bodies or energy made manifest on the human plane. The TT"5 within these i^oints represent the waters of the earth. And finally, the point below marked G for gonads, express- ing iimnoitality on the proereative plane. The E within this l)oint represents earth or the place where man must reach a certain stage in his unfoldment in order to be worthy of his Creator. Please note the numl)er of intercommunicating lines along which impulses or hormones or whatever we may choose to call them may travel. If we now look upon the large central J as the heart of man, we shall have a picture of him as the microcosm within the Universe and we may note how the adrenal, the jDituitary, the pineal, the thyroid, the thymus, and the gonads all liave their heart valency and how conversely the heart presents its radiant impulses impartially to all of them. The vast influence of these glands may be further graph- ically illustrated l)y lines or arrows going from the six points of llie stai- to all parts of llic body. Such as skin, hair, teeth, muscles, ligaments, lungs, li\cr, howcls, eyes, ears, nose, throat, that is, ])liai-yii\-, lai-ynx, tonsils, etc. The network is so vast and the interdependence so inti- mate that it would recjuii-e a volume of considerable size to cover tlie subject. 1 want to again express my sincefe obligation to those wjio before me ha\'e work'ed in this (iehl, and my keen a|)pi'eei;it ion of their efforts. If I liaNc omittiMl i;i\ini;- an\' one their due Kxnr)ri;iX()i)r)XT[A 381 credit foi" any ([notation oi* illnsti'ation, I licfcwitli acloiowledge my debt. To all who wonld delve more deeply into tlie various sub- jects treate of jjold when silicates are used, 287 of |ii)i-celain, ll'A |ilieiionieiui of, 302 ("oliiis. conijdenientarv, ,318, .j19 harmony of, 317 l)rimary, 312 prismatic, 317 rainljow, 317 secondaiy, 313 tertiary, 314 Condjiniiig weight of gold, 182 Compensatory dynamics of tlie cndo- crines, 365 Complementary colors, 318, 319 Complex cavity, defined, 75 in a bicuspid, 113 in a molar, 105 showing planes, 78 Conijiosition of wax, 127 Comi^ound cavity defined, 74 Compound cavities, prej)aration of, for porcelain, 329 Compound disto-occlusal cavity in bicus- pid, 83 Compound, fornuda for, 164 investment, 158 refractory, 158 Compound-carrying trays, method of tak- ing impression with, 146 Construction of splint for restoration of occlusal balance in cases of at- trition, 245 Contact lines, 215 points, 215 proximal, determination of, between molars, 258 Coordinate action, mental and physical, 42 Coordinate mental efforts, factors induc- ing, 24 Copper alloy, use of, in making amalgam die, 148 Copper band for making wax inlay, 136 Cosmetic functions of the teeth, 58 ('osmetic rea.sons for not using gold for tho inlay, 269 Creation, 47, 379 Creative force, 48 Crown, molar, carving of, 257 Crystallization of amalgam die, 151 of cement, 217 of the mold, 171 Cuspid, lower, restored by cast gold in- lay and porcelain in.sert, 281, 283 presenting cavity, 297 upper right, presenting a prehenso- labio-linguo-mesial deficiency, 399 Cus[)ids, angles of, 67 surfaces of, 67 D David, protector of, 379 Defensive functions of the teeth, 58 Dentistry, 50 Dentition, as to position, a thymopitui- tary and gonadopituitary func- tion, 377 as to cjuaiity, a thyroiiituitary func- tion, 377 as to resistance, a thyroadrenal func- tion, 377 as to time, a thvmopituitarv function, 376 Depth for cavity, 295 Developmental functions of the teeth, 58 Die, amalgam, making of the, 148 for procedure by indirect method, 139 Direct method, advantages of, 140 Direct method of making and carving the wax inlay, 131 Direct pressure machine, 200 Diseases, endocrine glands in relation to, 366 Di?to-buccal cavity in an upper molar, 97 Disto-occlusal cavitv in a molar, 95, 97, 342, 343 Disto-occlusal cavity tray, 144 Disto-occluso-buccal cavity in a molar, 107 Distorted mold, due to use of hot flask, 179 Drying out the mold, 173 Ductless glands, 359 E Elastic meml)rane surrounding teeth, function of, 54 Elasticity of suspension ligament, 118 Election of the case presenting a cavity, 64 3SG IXDEX Eli^iii \;u'iuiin i-;i?;tiiiy in;u*liiiie and Hasks, 19:2 Enamel seat of inlay, 77 Euilocrino giaiuls, in ii'lation to diseases, gonads, 364 pineal, 363 pituitary, 363 thyroid, 363 thymus, 363 suprarenal capsules, 363 Endoerines, 362 compensatory dynamics of, 36.3 Endocrinodontia, 359 Endocrinology, study of, 362 Errors and accidents primary causes of human ills, 49 Ether, elastic, in relation to light, 303 Eucalyptol compound, 235 Evolution, 48 Excess metal, removal of, 213 Exercise of tissues essential, 55 Extirpated pulp, 279 Extirpation of pulp in large restorations, 276 Face, normal, measuienients for, 249, 255 Feldspar, 323 Fillings, amalgam, jjoorly executed, as causes of mutilation' of occlusal surface, 236 Flask, special, 204 Taggart, 204 Floor of a cavity, preparation of, 114 Foil matrix for porcelain inlav, making the, 333 Formative factor iji cavity preparation, 71 Formula for a compound, 164 Fractured central, restored by gold in- lay and porcelain or the sili- cates, 271 Fractured lower lateral, 279 Frail teeth, gold for inlays in, 186 Function of elastic membrane surround- ing teeth, 54 Functions of the teeth, 52 active reciprocal, 58 general, 58 special, 58 passive reciprocal, 58 cosmetic, 58 defensive, 58 dcvclop)mental, 58 phonetic, 58 Fuiiiace, I'hitchock, 175 Fusing of j)Orcclain, 325 Fusing j)oint of gold, 182 of platinum, 182 G Gases, aljsorption of light by, 3U9 Gauge of wire for supplemental pins, 79 Gelatin impression of a model, 118 General active reciprocal functions of the teeth, 58 Geometric construction of molars, 257 Geometric landmarks of teeth, 65 Gingivae, condition of, in cases of attri- tion, 243 Glands, ductless, 359 Glass, color of, 311 Glazbrook, 304 Gold, alloving with platinum, 183 color of, 287 combining weight of, 182 for cast bases, 186 for inlay work, 182, 186 for saddles, 186 fusing jioint of, 182 inlay, and porcelain or the silicates in a fractured coutial, 271 and the silicates or porcelain, 269 and silicate cement to restore frac- tured lateral, 275 formula; for, 185 specific gravity, 182 symbol, 182 Gonadontia, 369 Gonadotroi^, 365 Gonads, 364 Graphite flakes, in investment, 106 paste, 233 post, 229 Grimaldi, 303 Grinding the porcelain matrix, 352 Gum tragacanth, 353 (rypsum, (•(lm[lo^itio^ of, 159 H llainioiiy of colors, 317 Healing art, 49 Health, function of gums ami teeth in, 52 general, should l)e looked after in cases requiring treatment for loss of occlusal balance, 242 Hertz, 303 High-fusing porcelain, 324 shrinkage of, 326 Hinged trays for taking impression of cavities, 144 Hook, 303 Hormones, definition of, 362 Hot (l;i.-k. use oT, in casting, gives dis- torted mold, 180 Hot water ;is a means of warming wax^ i:;i Hue ,,f .M.jcrs, :;] I IXDKX 387 llutcliiiisdii 's tectli, 7 "hatli, l.S.-) II vilidlluDi ic at-iil, cl(_•;lIl^:iillg of tin- i-ast- iny in, JUU making rceciitacle for, 210 Jlygienii- hindnmrks of the teeth, 69 Jlygroscopic characteristic of invest- ments, 165 Hvpnotics, use of, in cases of attiition, Ideal of a task, 46 Ideal wax for inlay work, i;!0 Immune areas of a tooth, 69, 70 Impression of the cavity, method of tak- ing, for proceduie by indirect method, 1:59 of the cavity, method of taking, witli eom])onnd trays, 146 trays, 339, 344 wax, direct method of taking, 131 Incision, 6U teeth as organs of, 52 Incisor teeth, angles of, do surfaces of, 65 Indirect method of making a cast gold inlay, 139 disadvantages of, 140 selection of, 139 Individual volition, 48 Inhibition, 362 Inhiliitory functions of the teeth, 60 Inlay, cast gold, 62 (see Cast gold in- lay) cementation of, 213, 315 placing in cavity for cementation, 213 polishing the, 213 jiorcelain, (see Porcelain inlay) restorations, poorly executed, inliilii- tory to function of teeth, r>o wax, making and carving of, by direct metliod, 131 work, 62 instruments for use in, 73 metals for, 182 wax suitable for, 129 Inlays, metallic, ()2 splinting loose teetli ])y means of, 218, 235 Inside of the tooth, 77 Instruments for the inlay worker, 7.'! Instruments for making tlie wax inlav, 137 Internal secretion, oigans of, 362 Investment compound, 158 Investment mixer, 168, 170 Investment of tin' matrix in preiiaratimi iif porcelain insert, 295 Iridio-platinum threaded posts, sizes for various teeth, 277 .lacki't I lowns, objections to, 293 Jill'y cement tube, 216 Jiffy tube, 286 Johnson, Dr., 331 K Kaolin, 323 Kaplan, Dr. I). M., .365 Kipling, 45 Labio-distolingual cavity in a lateral, 3.39 Laliio-ncclusal cavity in a molar, 342 Labi(j- or buccu-occlusal cavity, in a molar, 93 Landmarks for occlusal carving, 152 hygienic, 69 of teeth, geometric, 65 Lateral, cervical proximal cavitv in a, 341 fractured, restored by gold inlay ami silicate cement, 275 labio-disto-lingTial cavity in a, 339 linguo-mesial cavity in, 340 lower, fractured in a fall, 279 restored by cast gold inlay and syn- thetic porcelain, 273 Law of refraction, 306 Le Crone casting machine, 198 Life, in the abstract, 56 in the concrete, 56 Light, absorption of, 308 jihenomena of, 302 reflection, 305 refraction, 306 wave theory of, 303 waves, frequency of, 310 Lily-white, 37 Lingual surfaces of teeth to be splintecl, inlays for, 231 Lingiio-mesial cavity in a lateral, 340 Loose teeth, siilinting of, by means of inlays, 218, 2.35 Low-fusing porcelain, 324 shrinkage of, .■J26 Luminosity of color, 311 M Maciiines f(ir casting of the molten jnetal into tiie mold, 187 Magnesium, composition of, 162 Making wax inlay by direct method, 131 Malocclusion, end-to-end, as cause of at- trition, 242 its relation to prop(M- function of tlie teeth, 54 INDEX Malielation of teeth, as related to endo- criue glands, 375, 376 puberty in relation to, 377 Margins, burnishing of, after cementa- tion, 217 carving of, in wax inlay, 136 of the cavity, prei:aratiou of, 76 Mastication, 60 teeth as organs of, 52 Materials nsod in refractory conipound, 159 iratrix, foil, for porcelain inlay, 333 for porcelain insert, 295 in position upon a nio'ar, 141 making wax impression with a, 136 metal, making of porcelain inlay with- out, 337-357 ]iorcelain, 351 Measurements for normal face, 249, 255 Mechanical factor in cavity preparation, 71 Melt, making the, 183 Mental efforts, factors inducing coordi- nate, 24 IMercurv, removal of, from amalgam die, 150 Mesio- and disto-proximal cavity, 293 Mesio-disto-labio-ineisal deficiency in a central, cast gold inlay and syn- thetic porcelain insert for, 291 Mesio-disto-occlusal cast gold inlay, 12(1 Mesio-disto-occusal cavity, 120 preparation of, 121, 124 in a bicuspid. 87, 91, 111 in a molar, 99, 343 Mesio-disto-occluso-palatal cavity in a molar, 109 Mesio-labio-linguo-incisal deficiency, cast gold inlay and porcelain insert made for, 289 restored by cast gold inlay and syn- thetic porcelain, 285 Mesio-occlusal cavity, 85 in a lower molar, 343 tray, 144 Mesio-occluso-distai cavity in a bicuspid, 344 Metal, castiiig of, umliT jjicssure, ]97 castings made under juessure, 187 molten, casting into tlie mold, 178 removal of excess, 213 Metallic iidays, 62 Metals for inlay worker, 182 gold, 182 platinum, 182 Mineral wax, composition of, 128 Model, splint in jKJsition on, 247 Models, for study of stress index, 116 necessary for extensive restoration of occlusal balance, 240 study, 236 Models— Cont 'd. study of, in articulatdr, 246 Molar crown divided into thirds, 257 -Niolar, lower, mesio-oeelnsal cavity in a, 343 presenting a cervical cavity in the disto-labial surface, 341 presenting a complex cavity, 105 pi-esenting a deficiency of occlusal third, 103 presenting a disto-ocdusal cavity, 95, 342, 343 presenting a disto-occ'u^al cavity and a disto-buccal cavity, 97 presenting a labio-oeclusab cavity, 342 l^iesenting a labio- or bucco-occlusal cavity, 93 presenting a mesio-disto-occlusal cav- ity, 343 presenting a mesio-disto-occlusal cav- ity and a buccal cavity, 99 presenting a mesio-disto-occ'.uso-lniccal cavity, 107 presenting a mesio-disto-occluso-jialatal cavity, 109 reproduction of, in gold, 260 Molars, angles of, 68 detei-mlnation of proximal contact l)e- tween, 258 Mold, casting the molten metal into the, 178' drying out of the, 173 temperature of, in casting of molten metal, 178 Molten metal, casting into the mold, 178 casting of the, machines employed in ^187 Moore, Tom, 46 iMiuitli, ductless glands in relation to the, ;;59 Myrica Cei-ifera, 128 N Naso-mental line, normal, 249, 255 restoration of, 249 Xewton, Sir Isaac, 302 Xies, Dr., 337 Xitious oxiih} combined \vitli city gas to give nreessary iieat units in alloying, IS.'i Xiiiiiial face, measurements I'or, 219, 255 Xormal occlusion, illustrated, 117 Noyes, 72 Xynian, Dr., 216 O Occluded mode's of ca.'^e re(|uiiing res toiation, 151 Occluded study moile's, 2.'7 Occdusal balance, delinitiou ol', 239 extensixc i-estora tion (jf, by means of gold inlays, 2.'!() INDEX 389. Occlusal balance — ('out M. piclimiiiaiv jKiiiits necessary to rcs- toiatinn ()!', 240 rcstoiiition ol', view of case sliowiiii^, 254 splint to restore, 245 carving', metliofi of seciiiint;' lainl- marks for, ]52 surface of wax inlay, nietlioil of ob- taininfi", IHS surfaces, illustrations of, 263, 2(34 view of case sliowiiii;- attrition, 253 Occlusion, normal, illust latcil 117 traumatic, .'SfiM Occluso-disto-lin^ual jilane, 7!) Occluso-nu'sio-liuccal ])laiie, 79 On-iiilay, 321 (Jjieratixe factor in cavitv pic^iaration, 71 Optic sense, 24 Oral conditions in cases of attrition, 243 Osseous system out of harmony, cause of attrition, 242 Outside of the tooth, 77 Ovary in relation to incisors, 370 Oxyphosphate, melting point of, 354 Ozokerino, 129 Ozokerite, 128 ParafRne, composition of, 128 Parallel rays of light, 305 Paralleling- root canals of teeth to be splinted, 218 Parallelodrill, 218, 223 reaming out two root canals with, 224 Parallelometer, 218, 219 Parathyroid bodies, 363 Partial splints, 250 Passive reciprocal functions of the teeth, 58 cosmetic, 58 defensive, 58 developmental, 58 phonetic, 58 Pathologic anatomy, 360 Phenomena of light and color, 302 Phonetic functions of the teeth, 58 Piersol, 72 Pin vise, use of, in splinting teeth with inlays, 229 Pineal gland, 363 Pins, disadvantage of, 71 gauge wire for, 79 preparation of, 79 Pituitary body, 363 Pituitary teeth, 375 I'ituitodontia, 368 I'ituitotrop, 364 Planes of a molar crown, 257 IManes jircrerablc to ])ins in preparation, of cavity, 79 9 I'lastcr model of teeth, making of, 147 Plaster of Paris, 159 I'latcheck furnace, 173, 175, 176 IMatinum, alloying with gold, 183 combining weight of, 182 foil for matrix, 295 for inlay work, 182 fusing point, 182 specific gravity, 182 symbol, 182 Pf)lishing of cavity walls, 125 of inlay. 2i:! of wax inlay, 134 I'oicclain and cast gold inlay for res- toration of fractured lateral, 279 and gold inlays, 269 applicable for simple cavities onlv, 328 dental, composition of, 323 fusing of, 325 high-fusing, 324, 325 inlay, 83, 322 contraindications to, 322 foil matrix for, 333 for conqilex cavity in a bicuspid, 113 indications for, 322 making of, without use of a metal matrix, 337, 357 making Avax impression for, 336 l)reparation of cavity for, 328 insert and cast gold inlay for mesio- labio-linguo-incisal deficiency in a central, 289 and cast gold inlay in a cuspid, 281, 283 for disto-occlusal cavity in a molar, 95 taking impression for, 286, 295 low fusing, 324 matrix, 351 or silicates, and gold inlays in a frac- tured central, 271 replacing facial portions with a, 286 Positional symptomatic functions of the teeth, 60 Posterior teeth, loss of, as a cause of attrition, 242 Postnasal pituitary state, 376 Posts, iridio-platinum, sizes for various teeth, 277 rules in connection with use of, 277 Prehension, 60 teeth as organs of, 52 Prehenso-labio linguo-mesial deficiency, 299 390 INDEX Preliiuinary stops bcfoi-e lici^iniiino- a case of exte'iisivi' iH'stdiat ion. Prenatal pituitary state, .")7() I'roparation of an M.O.D. cavity, 121 of a cavity, (55, 76 of e^ivity for porcelain inlay, 328 Pressure machines in casting, ]91 all metal castings made under, 187 direction of application of, for vari- ous cavities, 153 effect of, on teeth, 54 Preston, 304 Price, Dr., 350 Price's stone model, 355 Primary colors, 312 Prismatic colors, 317 Procreation, 3(54 Properties of -wax required for inlay work, 129 Protector of David, 379 Proximal contact bet^veen molars, de- termination of, 258 Puberty in relation to malrelati.on of the teeth, 377 Pulp, extirpation (if, 27(5 Pyorrhea, 3<51 E Kadiation, 302 Kailrnads in relation to life, 33 L'ainbow colors, 317 Ti'apid heating, guard against, in dry- ing out mold, 174 Reading, influence of, to coordinate ac- tion, mental and physical, 43 Eeceptacle for hydroflnoric acid, mak- ing of, 210 Reciprocal functions of the teeth, ac- tive, 58 passive, 58 Reconstruction of molars ami bic\is- pids, 251 Record models, 230, 241, 249 Reflection of light, 304 angle of incidence, 305 incident ray, 305 Refraction of light, law of, .'idO licfractive index, 310 Refractory compound, ]58 investment of splint in, 250 Removal of decay in iircjiarat ion of cavity, 125 Resistance pinion, 214 Restoration, t-xtensive, a case of, 207 of occlusal bjilance, case showing, 254 of occlusal balance by means of cast gold inlays, 23(5 Roadi, Dr., instruments di'\ isrd by, 344 Root canals, paralb-Jing of, 2 bS Rubber liowl for mixing, 100 dam and clamp, 73 dam, use of, in cementation of the cavity, 215 S Saddles, gold for, ISO Sandarac for varnishing model, 152 Sanford, 314 Scalers, 73 Schafer, 72 Schellenon, 310 ■Schreier, Dr., 332 Seating the inlay, 217 Secondary colors, 313 Selection of case presenting a cavity, 64 of first tooth to operate upon in ex- tensive restorations of occlusal surfaces, 239 of jiroper wax, 127 Sense, auditory, 26 optic, 24 tactile, 31 Separating tilted teeth, 330, 331 Sequence of thought, 21 Seymour casting machine, 198 Shade of porcelain, 354 Shock to a tooth under stress mastica- tion, 118 Shrinkage of porcelain, 353 Silex, 323 and water paste, 295 Silicate cement and gold inlay to re- store fractured lateral, 275 Silicate, replacing facial portions with, 286 Silicates and cast gold inlays, 269 or porcelain and gold inlays in frac- tured central, 271 Silicon, composition of, 100, 101 Simple cavity, defined, 74 Simple occlusal cavity of upper first liicuspid, 81 Sinijilex casting macliine, 198 Slide for (;arrying (-oni]iouii(l, making of, 339-344 SiKdi's law of refraction, 30(5, 307 Sodium bicarbonate batii, cleansing of, casting in, 209 Solar sjicct rum, 30.S Soibrig machine, 199 S[)atula for mixing ccniciit, 21(i for ])lacing and holding impression mal ri-ial, ;'>.'!S Spccilic gra\ity of gold, 1.S2 of jilatinum, 182 S|)cct rum. .'iOS Splint, linislicil, i-cady to be in.sciicd, I.XDKX 391 S|)liiit -Cunt M. for restorat iciii »{' inilusiil li:il;iti(-c, 247 for i-cst or;it ion oC ncchisjil lialniici' in cases iif alt lit ion, 24.") uso of, in cases of attrition to rest me occlusal balance, 245 vulcanite, 24.S Si)lintinv means of inlavs, 21S- 235 Sprue wire, insertion of, in inlay, L'')4 use of, 124 Rtearine, 211 Sterilization of the cavity, 215, 21() Stokes, Mn4 Stress, a factor in restoring;- occlusal lialance, 2'M index, of l)icuspi(l, lower, .S.'], S7, Si), 9 upj.er, SI, S5, 111, 113 of central, lower, 271 upper, 2S9, 291. 293 of cuspid, lower, 281, 283 upper, 297, 299 of lateral, lower, 273, 275, 279 upper, 285 of lower teeth, 115 of molar, lower, 93, 95, 103, 107 upper, 97, 99, 105, 109 of upper teeth, 114 Structural sympotomatic functions of the teeth, (SO Study models, 23() Suction machine in castinji", 191 Sulcus reproduced in wax, inlay, 77 Su])plemental pins, preparation of, 79 SuprarcMial cajisules, .".03 Sure ('ast niarliine. ll'S Surfaces of Idcuspids. 73. Thymo-pituito-adicnal stress, 370 Thymotrop, 304 Thymus, 303 Thyroadrenal tooth, 205 Tliyrodontia, 300 Thyroid gland, 303 Thyroidal disbalance, 00 Thyroidal teeth, 375 Tilted teeth, separating, 330, 331 Time in relation of life, 33 Time spent in mixing compound, 107 Tin foil burni.shed on models, 245 Tissue must be exercised, 55 Toilet of the cavity, 125 Tooth anatomy, knowledge of, neces- sary to inlay worker, 152 Tooth surfaces and angles, 05 Touch, .sense of, 32 Towlc, Dr. Stanly, 357 Transparent objects, color of, 311 392 INDEX Traumatic occlusion, 360 Traumatic origin of loss of occlusal bal- ance, 241 Tray, compound-carrying, 338 Trays for taking impression, 344 for use with parallelodrill in splint- ing teeth, 229 hinged, for taking impressions of cav- ities, 144 Trituration, (30 U Undercuts in the matrix, 355 Unswaged matrix, advantage of, 357 V \'acuum machine for casting, 191 a pressure machine, 194 Van Woert, Dr. F. T., 330, 332, 337 Varnishing of model, 152 Vasoauxiliary functions of the teeth, 58 Vasomotor force in relation to the ad- renals, 371 Vibration in relation to light, 303 Vocalization, teeth as accessories of, 52 A'ulcanite splint, making and finishing, 248 W Waller, Ewan, .jliii Watts, Marshall, 310 Wave theory of light, 303 Wax bite, 151 Wax, bleaching of, ]-J:7 composition of, 127 Wax— Cout 'd. forcing into cavity, 131 impression for porcelain inlay, tak- ing the, 33C for porcelain insert, 286, 295 for silicate insert, taking of, 277, 286 use of, in making inlays for splint- ing teeth, 229 inlay, chilling with cold water, 135 for compound cavity, 135 for mesio-occluso-distal cavity, 124 instruments for making, 137 making and carving, by direct method, 131 making of, with matrix, 136 polishing of, 134 mineral, 128 mode], burning out the, 173 ozokerite, 128 parafitine, 128 pattern invested in comj^ound, 171 requirements for inlay work, 129 selection of, 127 splint, 246, 248 Taggart green, ideal for inlay work, 130 warmer, 131, 132 improvised, 134 white, 128 Weak Hands, 37 Wedgewood mortar ,149 Welden, Dr. F. S., 357 White wax, composition of, 128 Whitmell, C. T., 312 Wood, 304 Y Young, 303 1 COLUMBIA UNIVERSITY LIBRARIES This book is due on the date indicated below, or at the expiration of a definite period after the date of borrowing, as provided by the library rules or by special arrangement with the Librarian in charge. DATE BORROWED DATE DUE DATE BORROWED DATE DOE C28 (358; lOOM Technic ,iii,( -,,„ ,, , 2002376989 RKSh9 j1 iS NOV I 6 1925