CaUUMB.AL^RA|.|^J,^SjTE W 14X64071120 RK501 J621915 Aiext-bookotope^a_ RECAP ;i:(;r'':-:'ii,r'.ji,i < Columbia ®[nibergitp w^icr: ^cljool of Cental anb 0va\ burger? ^aeference Hihxaxv &' Digitized by the Internet Archive in 2010 with funding from Open Knowledge Commons http://www.archive.org/details/textbookofoperat1915john A TEXT-BOOK OF OPERATIVE DENTISTRY LIST OF CONTRIBUTORS. J. p. BUCKLEY. PH. G., D. D. S., Professor of Materia Medica and Therapeutics, Chicago College of Dental Surgery. W. A. CAPON. D. D. S.. Lecturer and Instructor of Dental Ceramics, Dental Department, University of Pennsylvania. GEORGE W. COOK. D. D. S., Dean of the College of Dent;stry, University of Illinois, Chicago. FERDINAND J. S. GORGAS. A. M.. M. D.. D. D. S.. Dean and Professor of Principles of Dental Science. Oral Surgery and Dental Pros- thesis in the University of Maryland, Dental Department; Author of " Dental Medicine." ELLISON HILLYER. D. D. S.. Professor of Prosthetic Dentistry and Orthodontia, New York College of Dentistry, GEORGE EDWIN HUNT. M. D.. D. D. S.. Dean and Professor of Operative Dentistry, Dental Pathology and Dental Hygiene, Indiana Dental College, Indianapolis. C. N. JOHNSON. M. A.. L. D. S.. D. D. S., Professor of Operative Dentistry in the Chicago College of Dental Surgery; Editor of " The Dental Review." C. EDMUND KELLS. JR.. D. D. S.. New Orleans. GARRETT NEWKIRK. M. D.. Member of the California State Board of Dental Examiners, Former Dean and Pro- fessor of Operative Dentistry, College of Dentistry, University of Southern California. JOHN EGBERT NYMAN. D. D. S., Chicago. ALFRED OWRE. B. A.. M. D.. CM., D. M. D.. Dean and Professor of Operative Dentistry and Metallurgy, College of Dentistry, University of Minesota. JOHN DEANS PATTERSON. D. D. S., Professor of Dental Pathology, Kansas City Dental College. HERMANN PRINZ. M. D.. D. D. S.. Professor of Materia Medica, Therapeutics and Pathology, Dental Department. Washington University, St. Louis. HERBERT A. PULLEN, D. M. D.. President of the American Society of Orthodontists, 1906-07; Instructor in the Angle School of Orthodontia. Session of moo; Member of the New York State Dental Society, Buffalo Dental Association, National Dental Association, etc. CHARLES R. TURNER, D. D. S . M. D.. Professor of Mechanical Dentistry and Metallurgy, Department of Dentistry, Uni- versity of Pennsylvania. A. E. WEBSTER. L. D. S., D. D. S.. M. D.. Professor of Operative Dentistry and Dental Pathology in the Royal College ai Dental Surgeons of Ontario ; Editor of " The Dominion Dental Journal," etc. GEORGE H. WRIGHT, D. M. D.. Former Assistant in Embryology and Histology, Harvard Medical School. A TEXT-BOOK OF OPERATIVE DENTISTRY BY VARIOUS AUTHORS EDITED BY C. N. JOHNSON. M. A., L. D. S.. D. D. S. PROFESSOR OF OPERATIVE DENTISTRY IN THE CHICAGO COLLEGE OF DENTAL SURGERY EDITOR OF THE "DENTAL REVIEW" THIRD EDITION, REVISED AND ENLARGED WITH 805 ILLUSTRATIONS PHILADELPHIA P. BLAKISTON'S SON & CO. 1012 WALNUT STREET ^' ys> zy^ -ti^oioi Copyright, 191 5, by P. Blakiston's Son & Co. Copyright, 1909, by P. Blakiston's Son & Co. Copyright, 1910, by P. Blakiston's Son & Co. Copyright, 191 i, by P. Blakiston's Son & Co. Reprinted, October, 1911. Reprinted, June, 1912. Reprinted, April, 1913. Reprinted, October, 1913. Reprinted, Jui;y, 1915 Reprinted, August, 1917. Reprinted, November, 1917- Reprinted, May, 191 8. Reprinted, August, 191 8. Reprinted, October, 1918. THE SIA1»X.E PKESS XORK PA. PREFACE TO THE THIRD EDITION. The preparation for the third edition of this work has involved much revision in some of the chapters, and the addition of two en- tirely new chapters — those on "The Treatment of Impacted Lower Third Molars," and "The Application of the Roentgen Ray to Den- tistry." These chapters have been contributed by Dr. C. Edmund Kells, whose excellent work along these lines makes him an authority on the subjects. The addition of these chapters rounds out the work into a more comprehensive treatment of the entire subject of Operative Dentistry, and makes it more valuable for the student and practitioner. The editor announces with profound sorrow the loss by death of three contributors since the second edition was issued, Dr. Geo. W. Cook, Ferdinand J. S. Gorgas, and George Edwin Hunt. In each case the authors revised their chapters before their death. With the careful revision that has been made and the introduction of new matter it is confidently believed that the present edition will be even more acceptable to the profession than the previous ones, the reception of which has been very gratifying to all those concerned in the production of the work. C. N. J. Chicago. PREFACE TO FIRST EDITION In preparing this book for the profession • the aim has been to condense the latest thought on the various subjects into the closest possible limit consistent with a clear elucidation of the ideas presented. It has been the constant effort to bring the work strictly up to date, and with the rapid evolution of dental thought in progress at the present time this has been no small task. As an illustration it is only necessary to mention the circumstance that one entire chapter — that by Dr. Nyman on the gold inlay — was wholly rewritten after it was in type and the illustrations made for it. The original article was discarded as being out of date the moment the cast method became a demonstrated fact. This is only indicative of the great care taken by the various authors in the revision of their work, and for which the editor wishes at this time to express his great appreciation. Particular attention is called to the illustrative character of the work. Most of the cuts were made specially for the book, and many of them are striking m their origmality. Those, for instance, illustrating Dr. Turner's chapter on "The Anatomy of the Human Teeth" were made from photographs of natural teeth, a typical specimen of each tooth being selected for this purpose and photographed on its different surfaces. The effect has been to present something perfectly true to nature. Mention might be made of distinguishing features in each chapter in the book, but this would appear unnecessary with the work in the reader's hands. It seems appropriate, however, to call attention to Dr. Pullen's chapter on "Orthodontia" which we believe is one of the most concise and practical presentations of this important subject that has yet appeared. To the contributors the editor feels under deep obligation for their cordial cooperation in preparing the work, and to the publishers for their uniform courtesy and painstaking care in every detail of publication. C. N. J. Chicago. Vll CONTENTS. PAGE Introduction, xiii BY C. N. JOHNSON, M. A., L. D. S., D. D. S. CHAPTER I The Anatomy of the Human Teeth i BY CHARLES R. TURNER, D. D. S., M. D. CHAPTER II The Histology of the Human Teeth, 60 BY CHARLES R. TURNER, D. D. S., M. D. CHAPTER III Hygiene and Arrangement of Light in the Operating-room, 85 BY C. N. JOHNSON, M. A., L. D. S., D. D. S. CHAPTER IV Asepsis in the Operating-room 89 BY A. E. WEBSTER, M, D., L. D. S., D. D. S. CHAPTER V Hygiene of the Mouth, 97 BY GEORGE H. WRIGHT, D. M. D. CHAPTER VI Dental Caries, 119 BY C. N, JOHNSON, M. A., L. D. S., D. D. S. CHAPTER VII Examination of Teeth for the Discovery of Carious Cavities, 131 BY GARRETT NEWKIRK, M. D. CHAPTER VIII Separation of Teeth Preparatory to Operating on Cavities in the Proximal Surfaces, 137 BY GARRETT NEWKIRK, M, D. CHAPTER IX Exclusion of Moisture from the Teeth during Operations, I49 BY GEORGE EDWIN HUNT, M. D., D. D. S. ix X CONTENTS. CHAPTER X PAGE Preparation of Cavities for Fillings, 165 BY A. E. WEBSTER, M. D., L. D. S , D. D. S. CHAPTER XI The Treatment of Sensitive Dentin, 219 BY J. P. BUCKLEY, PH. G., D. D. S. CHAPTER XII Filling Materials: Their Characteristics, Indications for Their Use and the Methods of Manipulation, 229 BY ALFRED OWRE, B. A., M. D., C. M., D. M. D. CHAPTER XIII The Use of the Matrix in Filling Teeth, 259 BY GARRETT NEWKIRK, M. D. CHAPTER XIV Inlays 267 BY C. N. JOHNSON, M. A., L. D. S., D. D. S. CHAPTER XV Preparation of Cavities for Inlays 271 BY C. N. JOHNSON, M. A., L. D. S., D. D. S. CHAPTER XVI The Porcelain Inlay, 281 BY W. A. CAPON, D. D. S, CHAPTER XVII Construction of Gold Inlays, 305 BY JOHN EGBERT NYMAN, D. D. S. CHAPTER XVIII The Treatment of Exposed or Nearly Exposed Pulps, 319 BY J. P. BUCKLEY, PH. G., D. D. S. CHAPTER XIX The Anesthetization and Devitalization of Pulps, Their Removal and the Subsequent Treatment, 325 BY J. p. BUCKLEY, PH. G., D. D. S. CHAPTER XX The Treatment of Ordinary Pericementitis, 343 BY J. P. BUCKLEY, PH. G., D. D. S. CHAPTER XXI The Chemistry of Pulp Decomposition 349 BY J. p. BUCKLEY, PH. G., D. D. S. CONTENTS. XI CHAPTER XXII PAGE The Treatment of Putrescent Pulps; Acute and Chronic Alveolar Abscess, with Complications; and the Filling of Root Canals, 355 BY J. P. BUCKLEY, PH. G., D. D. S. CHAPTER XXIII The Causes and Treatment of Discolorations of Teeth 375 BY J. P. BUCKLEY, PH. G., D. D. S. CHAPTER XXIV The Treatment of Children's Teeth, 385 BY C. N. JOHNSON, M. A., L. D. S., D. D. S. CHAPTER XXV Local Anesthesia, 393 BY HERMANN PRINZ, M. D., D. D. S. CHAPTER XXVI The Extraction of Teeth 419 BY FERDINAND J. S. GORGAS, A. M., M. D., D. D. S. CHAPTER XXVII The Treatment of Impacted Lower Third Molars, 459 BY C. EDMUND KELLS, JR., D. D. S. CHAPTER XXVIII The Planting of Teeth, . 473 BY C. EDMUND KELLS, JR., D. D. S. CHAPTER XXIX Pyorrhea Alveolaris, 487 BY JOHN DEANS PATTERSON, D. D. S. CHAPTER XXX Erosion, 507 BY GEO. W. COOK, D. D. S. CHAPTER XXI The Management of an Office Practice, 519 BY ELLISON HILDYER, D. D. S. CHAPTER XXXII The Application of the Roentgen Ray to Dentistry, 541 BY C. EDMUND KELLS, JR., D. D. S. CHAPTER XXXIII Orthodontia, 603 by herbert a. pullen, d. m. d. Index, 881 INTRODUCTION. Operative Dentistry may be defined as the science and art which aims at the preservation of the natural teeth in a state of health and beauty. Its highest office is to prevent disease or deformity, but where either of these has already occurred it is then its function to remedy the evil, and check its further progress. The dentist who does the best for his patient is the one who, in addition to the develop- ment of the highest manipulative skill, studies most care.fully the conditions surrounding the field of his operations. To fill a cavity in a tooth in the most perfect manner possible, when the surrounding tissues are in an abnormal condition, without a recognition of this fact and the most careful attention to the abnormality, is far from good practice. To attempt to remedy any disorder in the mouth by confining attention solely to the immediate seat of the trouble is fre- quently to court failure. The human economy is so complicated that cause and effect are often remote from each other, and the practitioner who does the best service to his patient is the one who in addition to being an acute observer extends his observation over the widest field. The conscientious dentist, when he finds himself baffied in dis- covering the cause or relieving the symptoms of any affection of the mouth will not hesitate to call in consultation a specialist in dentistry or medicine as the case indicates, and particularly is it desirable in instances of peculiar idiosyncrasies to consult with the family physician of the patient. No individual practicing a profession like dentistry should think lightly of his obligations, and no practitioner can properly fulfill his obligations without developing the habit of painstaking care in all his work whether of diagnosis or treatment. It should early be recognized by the young practitioner that dentistry demands of those who aim to excel in its practice a more diversified order of talent than any other calling. To be a good dentist an individual should develop the scientist's attitude toward the intimate and sometimes intricate relationship between cause and effect, he should be a close observer of phenomena, a mechanician of the first order, an artist with the sense xiii XIV INTRODUCTION. of harmony highly cultivated, a physician in his diagnosis of disease, a humanitarian in his ministrations to others, and above all a cultured gentleman of the highest mental and moral fiber. This does not imply that in the beginning he must be endowed with great brain capacity or natural attributes of an unusual char- acter. The encouraging thing about dentistry is that most of the qualities necessary for achievement are capable of cultivation, and the man who will apply himself with sufficient zeal and perseverance is certain of at least a reasonable measure of success. The chief requisite is the patience to plod. If every dentist would bring to his work a real sincerity of purpose to serve his patients to the highest possibilities of his art, the future of the profession would be secure. There would be less need than there is today of artificial teeth, and the full functional use of the natural organs in mastication and in harmony of expression would be more generally recognized and appreciated. As we develop dentistry along the lines of prevention and conservation we shall bring it nearer and nearer to its highest mission. To do the greatest good to the largest number, to do this good without thought of self advancement, to work for the love of it and for the benefit it brings to humanity — this is the acme of faithful service and the only kind of effort which will bring permanent satisfaction. Unless a dentist is willing to do this he will fall short of all that his profession has to offer him, if he does it he may be certain of an encouraging measure of attainment. But to accomplish anything of note he must be progressive. The methods of yesterday will not suffice for today. No profession is developing more rapidly than dentistry and he who would give the best service must ever be alive to the latest advances. The foremost thinkers of the profession are constantly placing their ideas before their fellow practitioners, and the man who keeps abreast must be alert to avail himself of the results of their matured thought. It is with the purpose of presenting this thought in the most condensed form as it relates to the different departments of operative dentistry that the present volume is issued. OPERATIVE DENTISTRY. CHAPTER I. THE ANATOMY OF THE HUMAN TEETH. BY CHARLES R. TURNER, D. D. S., M. D. The teeth of man are hard masses of calcified tissue attached to the mandible and maxilla and having as their chief function partici- pation in thework of his masticatory apparatus. His food, as intro- duced into the mouth, the beginning of the digestive tract, consists of articles of various degrees of physical consistency. In order that this may be prepared for subsequent stages in the digestive process, much of it must be mechanically subdivided into particles of convenient size to go through the alimentary canal and be acted upon by the di- gestive ferments and solvents. Such subdivision is performed in the mouth by the act of mastication and it is with this function that the teeth are chiefly concerned. They afford hard opposed surfaces which are brought into contact in the approximation of the jaws by the muscular apparatus and by this means the food is cut or crushed into particles of the desired size. The teeth also have a functional relationship with the apparatus by which voice and speech are produced and bear a cosmetic relation to the features of the face. The adult human denture consists normally of thirty-two teeth which are divided in number equally between the upper and the lower jaw. These are known as the permanent teeth, in contra-distinction to the temporary or deciduous teeth which serve for purposes of mas- tication during the earlier years of life and are subsequently exfoliated to give place to their permanent successors. The permanent teeth are divided anatomically into classes and these divisions largely correspond with their functions as portions of the masticatory apparatus. Thus, there are eight incisors, which Note. — The author desires to acknowledge his indebtedness for Figs, i to 84 inclu- sive to Dr. George J. Paynter, of the Department of Dentistry, University of Pennsyl- vania, who selected and dissected the specimens, and to the Department of Dentistry, University of Pennsylvania, for whom the photographs were made, for permission to reproduce them. 2 THE ANATOMY OF THE HUMAN TEETH serve in the incising of the food; four cuspids, whose chief function in the carnivorous animals is to pierce and hold the food, a function wholly rudimentary with man; eight bicuspids, which are intermedi- ate in position and function between the cuspids and the molars, and lastly twelve molars which are the crushing and grinding teeth proper. The formula for the permanent human dentition is expressed : l'-\ C'^, b'-', m3-3 = 3, 2-2 I-I 2-2 ^-^ The deciduous denture consists of twenty teeth — eight incisors, four cuspids and eight molars. As all the teeth possess certain characteristics in common it will be well to refer to these before undertaking a description of the in- dividual teeth. The crown of a tooth is that portion which projects beyond the gum margin and is normally covered with enamel. The root or roots of the tooth are imbedded in the alveolar process and are attached thereto by a fibrous membrane, the pericementum. The root and crown of a tooth unite at its neck, a point which corresponds to the point of juncture of the enamel and the cementum. This is also called the cervix and also the gingival margin of the crown. The sharp- ened extremity of a root is known as its apex, and this is the seat of an opening which transmits the nerves and blood vessels of the pulp of the tooth and is known as the apical foramen. The surface of a tooth which comes into contact with the corresponding surface of teeth in the opposing jaw is referred to as the occlusal surface. This term is also applied to the analogous portion of the incisor teeth although strictly speaking it should only apply to that of the lower incisors, in- asmuch as this edge of the incisors of the upper jaw does not touch the teeth of the lower jaw, when the teeth are in occlusal contact, but normally is only brought into this relationship when the mandible is protruded. This is also referred to as the incisive edge of the incisors. Molar and bicuspid teeth have large tubercles upon their occlusal surfaces and these are known as cusps. The adjoining surfaces of teeli are known as their proximal surfaces, the most prominent point of which is called the angle of the tooth. If a vertical plane is passed between the central incisors of both jaws, those proximal surfaces of the teeth which are directed toward this are known as mesial surfaces, while those proximal surfaces directed away from it are known as distal surfaces. The surfaces of the six anterior teeth of each series which are in relation with the lips are called labial, while the corre- THE UPPER CENTRAL INCISOR. 3 spending surfaces of the remaining teeth which are in relation with the cheeks are called buccal surfaces. Those surfaces of the teeth which are directed inward toward the cavity of the mouth are known as their lingual surfaces. The surface-form and internal anatomy of the permanent teeth will now be given in detail. THE UPPER CENTRAL INCISOR. The crown of this tooth is wedge-shaped; the base of the wedge is at its cervical margin from which the broad labial and lingual sur- faces converge to a straight cutting edge. Fig. I. — Left Upper Central Incisor. Labial Surface. Fig. 2. — Left Upper Central Incisor. Lingual Surface. The Labial Surface (Fig. i). — Irregularly quadrilateral in shape, this surface has four margins. The incisive edge which forms its lower margin is nearly straight; it is marked in the newly erupted tooth by two developmental grooves which disappear early in life be- cause of the wearing down of the three tubercles which are found on this edge. The mesial margin is nearly straight or may be a long 4 THE ANATOMY OF THE HUMAN TEETH. curve; the cervical border is convex rootward, while the distal margin is more convex than the mesial and is a little shorter. The surface itself is convex from the cervix to the incisive edge, the lower portion of it being, however, nearly flat, while that portion near the cervix is more curved and is marked by a cervical ridge. This face of the crown is convex from side to side and is marked by two longitudinal grooves which correspond to the lines of union of the three developmental lobes of the crown. The Lingual Surface (Fig. 2).— This is irregularly triangular, the mesial and distal margins uniting with the cervical to form a rounded Fig. -Left Upper Central Incisor. Mesial Surface. Fig. 4. — Left Upper Central Incisor. Distal Surface. apex, while the base of the triangle is formed by the incisive margin. The mesial and distal margins are marked by rounded ridges of enamel which extend from the angles of the crown in a graceful curve rootward to unite with the cervical ridge. The mesial is slightly the longer of these two. The cervical is more pronounced than the other marginal ridges. It is sometimes cut near its center by a fissure and sometimes it is the seat of a rounded elevation of enamel, the cingulum. The THE UPPER CENTRAL INCISOR. I'lG. 5. — Lclt upper Ceuiral Incisor. Incisal View. lingual surface is concave inciso-gingivally and mesio-distally. Its center is occupied by a pronounced fossa, the lingual fossa, which is traversed by two longitudinal grooves. Occasionally a lingual pit is present and this occupies a position at the juncture of the cervical ridge and the lingual fossa. The Mesial Surface (Fig. 3). — Being shaped like a spear-head or irregularly tri- angular in outline, this surface has three margins. The labial presents a long curve ending in the mesial angle of the tooth and is shorter than the lingual which it meets at this point. Both are bowed in a labial direction and the labial margin is the more pronounced, the lingual being rounded and marking less distinctly the boundary of the surface. The cervical margin is concave in an incisal direction and at its terminations unites with both the labial and lingual bor- ders at an acute angle. Near tlie incisive edge the surface is convex but this convex- ity decreases as the root is approached and the surface becomes either a plane or is marked by a slight depression at the gingival margin. The most prominent point of the surface is located one-third the distance from the mesial angle and this establishes the point of contact with the central incisor of the opposite side. TJie Distal Surface (Fig. 4).— While this is of the same general shape as the mesial surface, it is slightly smaller because of the location of the distal angle nearer to the cervix. Its margins are less distinct and the surface is more rounded and the point of contact with the lateral incisor is relatively nearer the cervix. The Incisive Edge (Fig. 5). — The in- cisive edge is formed by the intersection of the planes of the labial and lingual sur- faces of the crown. These do not meet at an acute angle but their line of intersection is somewhat rounded. This edge extends from Fig. 6. — Left Upper Central Incisor. Longitudinal section cut labio-lingually showing pulp cavity. THE ANATOMY OF THE HUMAN TEETH. the mesial to the distal angle, usually almost in a straight line. In young subjects it is marked by the developmental grooves, but these usually disappear from the wearing of the ■^■■■■■l^^l surfaces. When the crov^n is viewed from ■^^ ^^B below, the line of the incisive edge is oc- B _ ,,'. ^1 casionally bowed in a labial direction. t. ■ '^^SdK^H -^^^ Cervical Margin. — Beginning at the ^B^ jjj^^^HJ^H mesio-labial portion of this line, it extends ^^■jj^^^^^^^H with an upward curve upon the labial sur- ^^^^^^^^^^P face, downward on the distal, upward on Fig. 8. — Left Upper Central Incisor. Cross-section at cer- vix showing small pulp cavity in old tooth. Looking crowrn- ward. Fig. 7.— Left Upper Central the lingual, and downward again on the Incisor. Cross-section at cer- ;^ ^ ^j^ QJ^t of beginning. It is vix showing pulp chamber m ^ _ . . crown. Looking crownward. marked by the bulging of the cervical ridge on the labial and lingual surfaces. While there is usually a well- defined constriction on the tooth at this point, the neck of the tooth is not so marked as in some of the distal teeth. The Root. — This is conical in shape, and when viewed from the labial surface (Fig. i) its sides converge in almost straight lines to a rounded point; but viewed from the mesial (Fig. 3) or distal side the outlines of the root curve to a rounded point. When viewed in cross-section at the neck the labio- lingual diameter of the root is greater than the mesio-distal and the root outline is that of a rounded triangle with its sides corresponding to the labial, mesial, and disto-lingual faces of the root. Of these the mesial is the longest and nearly straight, the labial and disto-lingual being approximately equal in length but the labial is the most curved of all. The Pulp Cavity. — The form of the pulp cavity of the central incisor corresponds in general v^^ith the external form of the tooth JVd7„;!'°'oorsec.io"^ itself (Fig. 6). It is divisible into the pulp made at middle of crown chamber and the pulp canal, but the line of (looking rootward) showing .... . .. i i i j -t-u i form of pulp chamber, division IS not clearly marked. 1 he pulp chamber occupies the crown of the tooth and, as seen in a labio-lingual section of the tooth (Fig. 6) , follows the form of the crown closely. The pulp canal is conic in form, with its base THE UPPER LATERAL INCISOR. 7 joining the pulp chamber and its apex reaching the apex of the root where it terminates in the apical foramen. In a cross-section of the tooth-crown the flattening out of the incisal end of the pulp chamber to follow the incisive edge of the tooth, is seen. (Fig. 9.) The portions extending in the direction of the angles of the tooth are known as the "horns" of the pulp. In the young subject there are three concavities Fig. 10. — Right Upper Lateral Incisor. Fig. ii. — Right Upper Lateral Incisor. Labial Surface. Lingual Surface, in its occlusal end, corresponding to the three tubercles and the three de- velopmental centers of the incisive edge of the crown. A cross-section of the root at the cervix shows the pulp cavity almost circular in outline (Fig. 8), and this form characterizes it to the end of the root. The pulp cavity of this, as of all the teeth, diminishes in size from the time of completion of the root through old age because of the deposit of dentin upon its walls (Fig. 8). THE UPPER LATERAL INCISOR. The Labial Surface (Fig. 10). — This surface is somewhat similar in outline to that of the central incisor except that it is smaller, being narrower from side to side and shorter, and its distal angle is more rounded. It is bordered by four margins. The incisive margin is 8 THE ANATOMY OF THE HUMAN TEETH. almost straight, being, however, inclined slightly downward in the direction of the median line and in the young tooth is marked by developmental grooves which are less prominent than those of the central incisor. The mesial margin is nearly straight from the mesial angle to the cervix, being sometimes, however, slightly concave which causes a hook-like appearance to this surface of the tooth. The cer- vical margin is markedly convex rootward since the tooth is narrower than the central incisor, while the distal margin is also made convex Fig. 12. — Right Upper Lateral Incisor. Mesial Surface. Fig. 13. — Right Upper Lateral Incisor. Distal Surface. from the projection of its distal angle. The latter is longer than the mesial margin cicumferentially, but a straight line drawn from the distal angle to the cervix shows that this portion of the face is shorter than the mesial portion. The labial surface is more rounded in every way than that of the central. The cervical ridge and developmental grooves are present but are not so pronounced. The Lingual Surface (Fig. 11). — Like that of the central incisor, this surface is usually slightly concave, which is due to the projection of the mesial, distal and cervical marginal ridges. In outline it is nearly triangular. The incisive margin is the same shape as that de- THE UPPER LATERAL INCISOR. 9 scribed for the labial surface. The mesial and distal marginal ridges are well marked and unite with the cervical ridge. Both the mesial and distal margins are usually convex although the mesial may be almost straight. The distal is much shorter. The cervical margin is formed by the cervical ridge and is more frequently the seat of a cingulum than that of the central incisor. While the surface is usually con- cave in all directions, in some instances it may be almost flat. There is normally a well-defined fossa and in some cases this latter is marked with a longitudinal ridge corresponding to that on the labial face. The Mesial Surface (Fig, 12). — Shaped like an arrow-head, the cervical margin being concave, the labial margin of this surface is con- vex with a long curve. The lingual margin is less distinctly marked, is concave, and unites with the labial at the mesial angle of the crown. The surface is convex in its lower two-thirds but becomes flattened toward the cervix where sometimes a pronounced depression may exist. The point of contact with the central incisor is about one-third the distance from the cutting edge. The Distal Surface (Fig. 13). — This has the same general outline as the mesial but is more rounded in every way. The cervical margin is fig. 14.— Right Upper similar to that on the mesial face but the labial lateral incisor, Incisal view. and lingual are shorter, meeting at the distal angle which is less sharp and nearer the gingival margin than the mesial angle. The prominence of this surface makes this tooth quite different from, the other incisors and the surface is more nearly the shape of the mesial surface of the cuspid with which it is in contact. The Cervical Margin. — Although like the central in general char- acteristics, the labial and lingual portions of this line are more convex rootward, the latter being a sharper curve and extending proportion- ately higher than the labial. The mesial and distal portions are con- cave rootward, are similar in general form, and are quite angular. The Incisive Edge (Fig. 14). — This is proportionately shorter than that of the central, is often a nearly straight line between the angles of the crown and is usually slightly curved in a labial direction as the tooth, is viewed from below. Like the central incisor, at the time of its eruption it displays usually three developmental tubercles which indicate the three points at which calcification begins, but these are soon worn off. The Root. — The root of the lateral incisor has a general conical form, is often slightly longer than that of the central incisor, and is lO THE ANATOMY OF THE HUMAN TEETH. flattened mesio-distally. Its extremity usually has a slight distal bend. At the neck of the tooth it is almost circular in cross-section and is again at the apex, but the intervening portion exhibits the flattening above referred to and in some instances pronounced grooves upon the mesial and distal surfaces. In the center of its length the root is ap- proximately one-third greater in labio-lingual diameter than mesio- distally. The Pulp Cavity. — This corresponds in form to that of the tooth and differs but little except in size from that of the central incisor. Fig. 15- -Right Lower Central Incisor. Labial Surface. Fig. 1 6. — Right Lower Central Incisor. Lingual Surface. THE LOWER CENTRAL INCISOR. This is the smallest tooth in the mouth. Its crown is wedge-shaped (Fig. 17). The Labial Surjace (Fig. 15). — In outline this face of the crown is nearly triangular, the incisive margin being the base while the mesial and distal margins converge to the rounded apex formed by the cervical margin. The incisive edge is nearly straight and almost at right angles with the long axis of the tooth. The mesial and distal margins are THE LOWER CENTRAL INCISOR. II long curves, the distal being very slightly shorter and more curved. The cervical border is very short; the surface is convex from incisive edge to cervix, and, when seen in profile, is almost exactly the arc of a circle. Near the incisive edge the surface is nearly straight, the di- vision between it and the mesial distal surfaces being marked by fairly well-defined angles; as the cervix is approached, however, it becomes Fig. 17. — Right Lower Central Incisor. Fig. 18. — Right Lower Central Incisor. Mesial Surface. Distal Surface. more rounded. Like the upper incisors it is sometimes marked by two developmental grooves but these are normally poorly discernible except in young teeth. The Lingual Surface (Fig. 16). — Like the labial surface this is nearly triangular in outline but the rounded apex formed by the cervical margin is more nearly an acute angle. The surface is concave from incisive margin to the cervical ridge when this latter causes it to be marked with a convexity which ends abruptly by a well-defined margin at the neck of the tooth. The mesial and distal marginal ridges are usually poorly defined, the cervical ridge in which they unite corre- sponding with them in this particular except that it is usually somewhat 12 THE ANATOMY OF THE HUMAN TEETH. Fig. 19. — Right Lower Central Incisor. Incisal View. more easily traced. The incisal third of this surface is usually slightly bowed in a labial direction, making it concave mesio-distally, but this concavity gradually disappears before the center of the surface is reached. The Mesial Surface (Fig. 17). — This is tri- angular in outline, but unlike the labial and lingual surfaces the base of the triangle is directed rootward and is formed by a concave cervical margin. The sides of the triangle formed by the labial and lingual margins are curved in a labial direction, the labial being shorter and more curved and meeting the lingual at the mesial angle of the tooth. This surface is slightly convex, being most markedly so at its center just above which point it is in contact with its fellow of the opposite side. The Distal Surface (Fig. 18). — This is similar in outline and contour to the mesial surface, except that it is shghtly shorter and is more convex in its incisive third because the labial and lingual margins meet in a more rounded eminence the distal angle. Near the cervical margin it is often slightly concave, in which instance the concavity is commonly continued up the root as a longitudinal de- pression. The Incisive Edge (Figs. 15 and 19). — Like those of the upper jaw the lower central incisor at the time of its eruption is usually characterized by the presence of three tuber- cles upon its incisive edge. These are soon worn off and the edge is then straight. It occupies a line at right angles to the long axis of the tooth, terminating in the mesial and distal angles of which the former is slightly the more pronounced. The Cervical Margin. — This is similar in outline to that of the upper incisors except that it is more angular. On the mesial and distal surfaces it is markedly concave in the direction of the crown and extends rootward on the lingual and the labial surface. The lingual portion is short and angular, which Fig. 20. — Right Lower Central Incisor. Labio- lingual longitudinal section showing bifurcation of pulp canal. THE LOWER LATERAL INCISOR. I3 latter characteristic is caused by the projection downward of the abrupt cervical ridge of this surface of the crown. The labial portion of the cervical margin is convex rootward but less sharply so than the lingual. The Root. — The root on this tooth is more delicate than that of any other in the mouth. It is conical in shape, being much flattened upon its mesial and distal sides (Figs. 17 and 18) at the cervix from which point these surfaces, slope in almost straight lines to the apex. This latter is sometimes slightly deflected in a distal direction. These sides of the root are frequently marked with longitudinal grooves which ex- tend almost to the apex. The labial and lingual aspects of the root are narrow, the former being the wider and they converge gradually to within a short distance of the apex when they rapidly ap- proach each other and give the root a rounded ap- pearance which is observed when it is viewed from the mesial or distal side. The labial surface of the root continues the line of that surface of the crown, making with it almost a perfect arc of a circle. Lower Cental 'in- The Pulp Cavity. — This cavity follows the cisor. Cross-section of . crown near its middle general form of the exterior of the tooth and only looking rootward. a few points need to be touched upon in its de- scription. The horns of the pulp chamber extend well toward the mesial and distal surfaces, but the cavity is very narrow labio-lingually at its extremity. There is no perceptible line of division between this and the pulp canal. The latter is flattened and narrow in its beginning at the cervix (Fig. 20) and occasionally divides into two canals which usually unite near the apex and terminate in a single foramen. In most instances, however, it exists as a small, slightly flattened canal. THE LOWER LATERAL INCISOR. This tooth so nearly resembles the lower central incisor that sepa- rate description seems superfluous, therefore only its differentiating characteristics will be pointed out. It is wider mesio-distally than the lower central incisor; its distal angle is more rounded and its distal surface slightly more convex. Its root is somewhat longer than that of the lower central incisor and at its apex is often bent distally. The pulp chamber is similar in all respects to that of the lower central in- cisor except that it is slightly larger in its coronal portion in corre- spondence with the greater size of the crown. 14 THE ANATOMY OF THE HUMAN TEETH. THE UPPER CUSPID. The crown of this tooth presents for examination four surfaces and a cusp. The Labial Surface (Fig. 22). — The outline of this surface shows that it is bounded with five margins. The incisal portion provides two, the mesial and distal incisive edges. The former of these extends from the point of the cusp to the mesial angle, being either concave because of the presence of a developmental Fig. 22. Right Upper Cuspid. Labial Surface. Fig. 23. — Right Upper Cuspid. Lingual Surface. groove or it may be slightly convex. The distal incisive margin which extends from the cusp to the distal angle is usually longer than the mesial incisive and more frequently marked with a slight convexity. The wearing down of the cusp in adult teeth usually results in making the point of separation between these margins less distinct. The mesial margin of the labial surface is convex, as is also the distal which descends from the distal angle of the crown. The cervical margin follows very much the same curve as that of the central incisor, the highest portion of its convexity, however, being a little nearer its mesial THE UPPER CUSPID. 15 end. The surface is convex from cusp to cervix and also from the mesial to the distal angle but is sometimes marked by two longitudinal developmental grooves. These, beginning nearer the mesial and distal angles than the cusp of the crown, ascend toward the cervix, gradually disappearing about the upper third of the surface. The labial ridge ascends from the cusp, being located nearer the mesial than the distal surface of the crown, and gradually blends with the rounded convexity of the upper third of this surface. When the developmental grooves Fig. 24. — Right Upper Cuspid. Mesial Surface. Fig. 25. — Right Upper Cuspid. Distal Surface. are not marked the labial surface mesial to the ridge is more convex than that distal to it. The Lingual Surfaee (Fig. 23). — With much the same outline as the labial face, this surface is slightly smaller, bat is proportionately longer from cusp to cervix, and has a shorter and more convex cervicd margin. The surface has a general convexity and is marked by a lingual ridge which ascends from the cusp and does not fade away until it reaches the cervical marginal ridge. It corresponds in posi- tion to the labial ridge of the opposite face of the crown. In dis- tinctly marked teeth there is a groove on either side of this ridge. i6 THE ANATOMY OF THE HUMAN TEETH. Fig. 26. — Right Upper Cuspid Incisal View. The cervical marginal ridge is usually a pronounced, rounded eleva- tion affording a distinct line of demarcation between the crov^n and root of this tooth. It is frequently the seat of an elevation at or near its center, and may have a fissure dividing the ridge on either or both sides of the cingulum. The mesial and distal marginal ridges are less well marked than the cervical from which they extend to the mesial and distal angles of the crown. The mesial is the longer and better defined. The Mesial Surface (Fig. 24). — Shaped like an arrow-head, the labial boundary convex and the lingual usually concave, the outline of this surface is completed by the concave cervical margin. The lowest portion of this latter is slightly nearer its junction with the labial than with the lingual margin. The mesial angle which is the meeting ground of the labial and lingual margins is just below the point at which this tooth is in contact with the lateral incisor. It is not quite so near the cervix as is the distal angle. The surface is nearly convex in its lower two-thirds but above this point may be flat or slightly concave. The Distal Surface (Fig. 25). — This is similar in shape to the mesial but is some- what smaller in extent and more convex. The distal angle is more protuberant than the mesial and just above it is a rounded point with which the tooth is in contact with the first bicuspid. The cervical margin is less concave than the mesial and its highest portion is nearer the labial than the lingual margin. The Cusp (Fig. 26). — This is the prominent point of the cutting edge and is formed by the union of the mesial and distal cutting edges and the labial and lingual ridges. It is sharp in well-marked teeth at the time of eruption but the point is soon worn down and may be blunt or rounded. The Cervical Margin. — Convex labially and lingually and concave Fig. 27. — Right Upper Cuspid. Longitudinal sec- tion cut antero-posteriorly showing pulp cavity. THE LOWER CUSPID. 1 7 mesially and distally, this margin corresponds closely to that of the upper central incisor. The Root. — Like that of all single-rooted teeth the root of the upper cuspid is conical. On all its four sides it gradually tapers from the cervix to the apex. In cross-section at the cervical margins (Fig. 28) it is ovoid or may be almost circular. In the former instance the labial side is the segment of a larger circle than the lingual. The mesial and distal aspects of the roots are often flattened, in which case their centers sometimes present poorly marked longitudinal grooves. At the apex the root is usually inclined in a distal direction or the whole root may have a slight distal curve. The Pulp Cavity (Figs, 27 and 28). — In the young tooth there is a pronounced pro- pir^ct-S^^afce™" jection of the pulp chamber wall toward the looking crownward, showing . , . , 1 ., , shape of pulp cavity. cusp of this tooth, but as it becomes more mature the pulp cavity becomes more flattened here. Otherwise it is very much like the external form of the tooth, extending well toward the mesial and distal angles, and closely resembling that of the central incisor. At the level of the cervix it is oval in cross-section and ex- tends gradually diminishing in size to the apex. There is no line of demarcation between the root and coronal portion of the cavity. THE LOWER CUSPID. The crown of the cuspid of the lower series is very similar to that of the upper, except that it is narrower, more delicate and slightly longer, and usually not so well marked. The Labial Surface. — The markings of this surface are not so pro- nounced as those of the upper cuspid. The outline is less angular than that of the upper, with the exception of that portion formed by the mesial and distal incisive edges, for its cusp is more pointed than that of the upper cuspid. The developmental grooves are usually poorly defined, the labial ridge being the most prominent mark- ing of this surface and giving to it a marked convexity. This ridge, as in the upper cuspid, is located decidedly nearer the mesial than the distal margin. The mesial margin is more pronounced than the distal, the labial surface meeting the mesial somewhat more abruptly than the distal into which it passes by a rounded curve without definition. l8 THE ANATOMY OF THE HUMAN TEETH. The Lingual Surface. — The outline is more rounded and the sur- face markings less bold than those of the upper cuspid. The marginal ridges are usually poorly defined, that at the cervix being more prom- inent than the mesial or distal. The lingual ridge extends from the cusp to the cervix, dividing this surface and forming two very shallow grooves or fossae, the lingual grooves; but the surface is less convex than that of the upper, especially at the occlusal end, which is some- times flat mesio-distally. The Mesial Stir face. — Similar in shape to that of the upper, yet differing from it in some particulars, this surface of the lower cuspid possesses the peculiarity of being almost flat and being continuous as an almost plane surface with the root. At the cervix it is slightly con- cave or it may be simply flat, but it assumes a convex character as the mesial angle is approached. The cervical outline is much less concave rootward than that of this face of the upper cuspid, but similarly it extends to a lower .level lingually than labially. The lingual margin is well defined but the labial is rounded. The Distal Surface. — The convexity characteristic of this surface of the upper cuspid is observed here, except that the cervical portion is sometimes slightly concave. The surface is smaller in extent than the mesial, a fact due to the lower location of the distal angle. The cervical margin is pronounced, the surface of the root usually forming a decided angle with that of the crown. The lingual margin is more marked than the labial, but by comparison both are less clearly defined than those on the mesial surface. The Cusp. — The prominent point of the tooth occupies a line al- most in its long axis. From it descend the mesial and distal incisal edges of which the latter is slightly longer, but the difference is not so marked as in the upper cuspid. The Cervical Margin. — This is concave in the direction of the root on the labial and lingual sides and convex on the mesial and distal. On the lingual and distal sides the root and crown join more abruptly than on the mesial and labial. The Root. — The root is shorter than that of the upper cuspid and is flattened on its mesial and distal sides. Viewed in profile from any of the four surfaces its sides slope gradually to the apex which is frequently inclined to the distal. The Pulp Cavity. — This resembles that of the upper cuspid except that it is narrower mesio-distally, a difference in form likewise ob- servable in the crowns of the two teeth. It has no horns of the pulp chamber but terminates in a pointed extremity beneath the cusp. THE UPPER FIRST BICUSPID. 1 9 The pulp canal is flattened mesio-distally at the cervix but becomes circular in its apical portion. THE UPPER FIRST BICUSPID. The crown of this tooth presents for examination five surfaces, namely, occlusal, buccal, lingual, mesial and distal. It is irregularly cuboidal in shape. The Occlusal Surface (Fig. 29). — When vievv^ed from the occlusal surface the crown appears ovoid in outline, whereas the occlusal surface proper is trapezoidal, the oval appearance being due to the projection of the buccal and lingual faces of the tooth. The most prominent features of this surface are the two cusps sur- mounting its buccal and lingual portions, the buccal and lingual cusps, which are separated by the central groove and which give to the tooth its distinguishing character (bicuspid). The margins are formed by the buccal cusp with its descending mesial and distal inclines, the mesial and distal marginal ridges, which ,,jj;j.j r !••• 4.U Fig. 20. — Left Upper First are well-defined ridges of enamel jommg the Bicuspid. Occlusal Surface, ridges of the buccal cusp at the mesial and distal angles of the crown and converge to join descending ridges from the lingual cusp and the lingual cusp itself. The buccal cusp is the larger, sharper and more prominent. From its summit four ridges descend; the buccal ridge, which is partly responsible for the prominence of the buccal surface of the crown; the triangular ridge, which extends downward toward the central groove and usually terminates there; and one each mesially and distally to reach the mesial and distal angles respectively. Of these latter two, the distal is usually the larger and the more inclined, the point of the cusp being usually nearer the mesial than the distal face of the crown. The lingual cusp is lower and much more rounded than the buccal and the three ridges descending trom it are less pronounced. The triangular ridge is often missing but when present it descends toward the central groove to meet the ridge from the buccal cusp. Occasion- ally these two triangular ridges unite and form the transverse ridge, but usually they are separated by a fissure in the central groove. The ridges descending mesially and disially from this cusp join and are continuous with the marginal ridges, being curved so that the lingual outline of the occlusal surface is much rounded. The lingual aspect 20 THE ANATOMY OF THE HUMAN TEETH. of the lingual cusp is convex and rounded and gradually blends with the lingual surface. The mesio-distal groove separates the cusps and extends from the mesial to the distal marginal ridges. It is sometimes extended at each extremity into the mesial and distal developmental grooves which when present are fine lines crossing the marginal ridges to reach the mesial and distal surfaces of the crown. The triangular grooves are short, cross the central groove at its terminations at right angles, ex- FlG. 3°- -Left Upper First Bicuspid. Buccal Surface. Fig. 31. — Left Upper First Bicuspid. Lingual Surface. tend toward the angles of the crown, and separate the mesial and distal marginal ridges from the triangular ridges. The junctions of these grooves with the central groove are often spoken of as the mesial and distal pits. The Buccal Surface (Fig. 30). — This closely resembles in form and outline the labial surface of the cuspid tooth, being smaller and more compressed occluso-gingivally. It is bounded by four margins, the occlusal, the cervical, the mesial and the distal. The occlusal is formed by the mesial and distal inclines of the buccal cusp and is well defined. The mesial incline is usually a straight line or is slightly convex, THE UPPER FIRST BICUSPID, 21 while the distal may be marked with a concavity caused by the distal buc- cal groove. The mesial border is more sharply defined than the distal. It descends from the mesial angle to the cervical border, which latter is nearly straight or may be slightly convex rootward and is not distinctly marked by an abrupt termination of the enamel. The distal margin is usually shorter and more rounded than the mesial, because of the lower position of the distal angle, and the fact that the buccal surface rounds into the distal without a sharp line of definition. The buccal Fig. 32. — Left Upper First Bicuspid. Mesial Surface. Fig. 33. -Left Upper First Bicuspid. Distal Surface. ridge, descending from the buccal cusp and flanked by the buccal developmental grooves, which are forced well towards the angles of the crown, contributes towards the convexity of this surface. It usually disappears by blending with this convexity about the center of the surface, but occasionally in well-marked teeth it extends almost to the cervical margin. The greater mesio-distal diameter of the crown at the level of the angles than at the cervical margin gives to the crown its characteristic bell-shape, which may be well observed when looking at it from the buccal side. The Lingual Surface (Fig. 31). — This face is smaller than the buccal, being both shorter and narrower. It is convex mesio-distally 22 THE ANATOMY OF THE HUMAN TEETH. and rounds into the mesial and distal face without line of demarca- tion. Its occlusal margin is also rounded, being formed by the lingual cusp and the ridges descending from it, while the gingival margin is either nearly straight or is only slightly convex rootward. The sur- face is curved from the summit of the lingual cusp, which is slightly nearer the mesial face of the crown, to the cervix, its outline when seen in profile being a long gentle curve. It is usually quite smooth and without grooves. The Mesial Surface (Fig. 32). — Ir- regularly quadrilateral in shape, this face of the crown is bordered occlusally by the mesial marginal ridge and a portion of the ridge from the lingual cusp, and gingivally by the cervical line which is usually nearly straight or slightly concave in the direction of thei root. The occlusal margin is concave, the concavity being about midway be- tween the cusps. Frequently this margin is broken by the mesial de- velopmental groove which reaches this face from the occlusal surface and usually terminates about its center. The buccal margin is fairly well de- fined and extends from the mesial angle to the cervix, while the lingual is so rounded by the gradual joining of the lingual surface as to be indistin- guishable. Near the occlusal margin the surface is full and rounded, giving a point of contact for the proximal side of the cuspid, but it flattens out as the cervix is ap- proached and in this location is usually the seat of a depression which is continued up the face of the root. The Distal Surface (Fig. 33). — While this is much like the mesial surface, it is smaller in extent and more convex. The buccal margin is not so pronounced as that of the mesial face and is usually shorter. The cervical, lingual and occlusal margins are very much like those of the mesial fac ■ and the lingual is poorly defined and much rounded. In its occlusal third the surface is quite convex in all directions and this usually extends in decreasing degree to the cervix, although the corresponding portion of the mesial face is usually concave bucco- FiG. 34. — Left Upper First Bicuspid. Bucco-lingual longitudinal section, showing pulp chamber, its horns, and the pulp canals. THE UPPER FIRST BICUSPID. 23 lingually. The distal developmental groove sometimes crosses the upper margin from the occlusal surface and disappears about the center of the surface. The Cervical Margin. — This is more nearly straight around the tooth than that of any of the teeth so far described, usually having, however, a slight curve rootward on both buccal and lingual surfaces and being curved toward the occlusal surface on the mesial and distal faces. The Root. — The upper first bicuspid usually has two roots (Fig. 32) or two branches of its root, which are located beneath its two cusps and are called the buccal and lingual roots. Occasionally the tooth has only one root, or the division may occur very near its apex. In the former instance the central portion of the root between the two pulp canals is thin and usually consists only of cementum. The occurrence of two separated roots is most frequently noted and in this instance the roots are delicate and taper gradually to a somewhat sharp apical extremity and are usually curved in several directions. These curves are usually first in a buccal and lingual direction, serving to separate the roots which again approach each other at their termi- .^ . , ,. . . Fig. 35. — Left Upper nations. There is often a gentle distal curve in First Bicuspid. Cross- both roots. The bifurcation is usually located rhoSlTapr ""S about one-third the distance from the cervix, and canal, is accomplished by a meeting of the groove noted on the mesial face of the root and originating in the crown, with one which develops above the cervix on the distal side of the root. The Pulp Cavity. — The pulp chamber and the pulp canal are usually diflferentiated in this tooth (Fig. 34), the chamber correspond- ing to the general shape of the crown, the canals to the form of the roots. The chamber is a cavity with flattened mesial and distal walls and curved buccal and lingual walls. In the mature tooth these latter are nearly parallel and terminate occlusally in the buccal and lingual horns of the pulp chamber, which are cone-shaped projections of the cavity penetrating the two cusps. The occlusal wall of the chamber is marked by a projection corresponding to the central groove of the occlusal surface of the crown. In horizontal cross-section at this level, the cavity is larger than at the cervix, the mesial and distal walls converging to this point in correspondence with the external surface of the crown. 24 THE ANATOMY OF THE HUMAN TEETH. The floor of the pulp chamber, which is usually about on a leveJ with the cervix, differs in character in accordance with the root forma- tion of the tooth. In teeth with two roots or in those with two root canals, the buccal and lingual walls of the chamber are continued as the corresponding walls of the two pulp canals, but in old teeth a line of definition between the two is caused by an inward projection of the wall. The openings to the two canals are funnel-shaped and are separated by a ridge corresponding to the root bifurcation. The canals are usually about circular in cross-section, and follow the directions of the roots, occupying their centers. When the tooth has only one root, it sometimes has only one pulp canal (Fig. 35), which is flat and ribbon- like in its gingival portion, becoming more nearly round as the apex is reached. Often in single-rooted teeth there are two pulp canals, which either terminate in separate foramina close together or coalesce just before reaching the apex, a single canal making exit at the apex» THE UPPER SECOND BICUSPID. This tooth so closely resembles the upper first bicuspid that it will only be necessary to point out the differences between the two. The crown of the tooth is smaller and its prominences are more rounded than those of the first bicuspid. It is always shorter from cusps ta cervix but the bucco-lingual diameter at the cervix is sometimes slightly greater than that of the first. On the occlusal surface (Fig. 36) both cusps are more rounded, and, unlike the first bicuspid, are usually of equal length. The lingual cusp is usually equal in size to that of the first bicuspid while the buccal is smaller, in consequence of which facts the two cusps of this tooth are approximately equal in size. The tri- ^ ^ _. , , angular ridges usually unite to form a trans- FiG. 36.— Right Upper Second & & -^ , , , Bicuspid. Occlusal Surface. verse ridge, the central groove is shortened mesio-distally, and usually terminates in pits instead of well-marked triangular grooves. The buccal (Fig. 37) and lingual (Fig. t,S) faces of the crown are smaller and more rounded than those of the first bicuspid, the mesial (Fig. 39) and distal (Fig. 40) faces being similar to those of the first except that the concavity on its mesial face near the cervical margin is missing. This is one of the chief distinguishing features of the tooth. The cervical margin more nearly occupies a horizontal plane than that of the first bicuspid, being. THE UPPER SECOND BICUSPID. 25 Fig. 37. — Right Upper Second Bicuspid. Fig. 38.^Right Upper Second Bicuspid. Buccal Surface. Lingual Surface. Fig. 39. — Right Upper Second Bicuspid. Fig. 40. — Right Upper Second Bicuspid. Mesial Surface. Distal Surface. 26 THE ANATOMY OF THE HUMAN TEETH. slightly curved rootward on buccal and lingual surfaces and being almost straight on the mesial and distal sides. A single root is char- f 10. 41. — Right Upper Second Bicuspid Bucco-lingual longitudinal section, showing^ pulp cavity. Fig. 42. — Right Upper Second Bicuspid. Mesio-distal longitudinal section, looking buccally. Showing pulp cavity. acteristic of this tooth. It is much flattened on its mesial and distal sides and is usually marked with a longitudinal groove on each of these surfaces. Its extremity is usually rounded and occasionally bifid. Its buccal and lingual surfaces converge much more in reaching the apex than do its mesial and distal. The root sometimes has a curve in a distal direction near its termination. Inasmuch as this tooth normally has but one root, the pulp cavity consists of a pulp chamber corresponding in shape to that of the crown and a single pulp canal (Fig. 41). While the pulp chamber is similar in form to that of the first bicuspid, the horns of the chamber are less pointed and penetrating, because of the dififer- ences in the cusps of these two teeth. The pulp canal has its walls continuous v/ith those of the chamber, no definite demarcation be- j Fig. 43. — Right Upper Second Bicuspid. Cross- section of root above cer- vix, showing pulp canal. THE LOWER FIRST BICUSPID. 27 tween the two existing. It is narrow mesio-distally and ribbon-like at the cervix but is usually easy to enter (Fig. 43). Occasionally this tooth has two roots, in which case two root canals can be found, and their existence should be considered among the rare possibilities in the treatment of these teeth. THE LOWER FIRST BICUSPID. While partaking of the characteristics of the upper bicuspid teeth, the lower first bicuspid departs from the typical bicuspid design in the rudimentary development of its lingual cusp. The great variation in the development of this cusp accounts for the variations in form so commonly observed in this tooth. The Occlusal Surface (Fig. 44). — Viewed from the occlusal surface the outline of the crown appears almost circular or ovoid but this is due to the fact that the upper portion of the bulging buccal face is visible. The surface presents for examination a buccal cusp, either a lingual cusp or a lingual ridge, a mesial and distal pit and marginal ridges bordering the surface. The summit of the buccal cusp is nearly in the line of the long axis of the crown. Four ridges descend from it, one each in a buccal, lingual, mesial and distal direction. The two latter unite at the mesial and distal angles with the marginal ridges. The buccal extends upon the buccal face of the crown and ... Till- Fig. 44. — Left Lower First the Imgual is more strongly developed, is not Bicuspid. Occlusal Surface. crossed by a groove, reaches the lingual ridge or lingual cusp, and separates the mesial and distal pits. The mesial and distal marginal ridges converge to unite and form a semicircle with a lingual prominence of enamel, which when much elevated above the adjoining margin ridges is considered the lingual cusp and when only existing as a ridge is called the lingual marginal ridge. The Buccal Surface (F g. 45). — This corresponds so closely to that of an upper bicuspid that detailed description would be superfluous. The cusp is not so pointed, the buccal developmental grooves are poorly developed, the crown is shorter and narrower than its fellow of the upper series, the cervical line is almost straight, and the surface is convex and slopes inward to the summit of the buccal cusp which is usually in line with the long axis of the root. The Lingual Surface (Fig. 46). — This is small because of the small 28 THE ANATOMY OF THE HUMAN TEETH. Fig. 45. — Left Lower First Bicuspid. Buccal Surface. Fig. 46. — Left Lower Fir.st Bicuspid. Lingual Surface. Fig 47. — Left Lower First Bicuspid. Mesial Surface. Fig. 48. — Left Lower First Bicuspid. Distal Surface. THE LOWER FIRST BICUSPID. 29 size and low position of the lingual cusp. The occlusal margin is well defined and the surface is nearly straight from this point to the cervix and in many instances is continued without marked division into the surface of the root or it may make an obtuse angle with this face of the root. Mesio-distally it is much rounded passing into the proximal surfaces with a gentle curve. The Mesial Surface ' {Fig. 47). — Irregularly quadrilateral in out- line, with only its occlusal margin well defined by the marginal ridge, Fig. 49. — Right Lower First Bicuspid. Mesio-distal longitudinal section, showing pulp cavity. Fig. 50. — Right Lower First Bicuspid- Bucco-lingual longitudinal section, show, ing pulp cavity. this surface is generally convex. The most prominent point of the convexity is located centrally just below the occlusal margin from which the surface inclines inward toward the central axis of the tooth, con- tributing thereby to give the bell-shape which is observed of this crown as it is viewed from the buccal or lingual side. At the cervix the surface is flattened. The Distal Surface (Fig. 48). — This is almost similar to the mesial except that its convexity is usually less pronounced. The Cervical Margin. — The juncture between enamel and cemen- tum in this tooth occupies nearly a horizontal plane, being continued 30 THE ANATOMY OF THE HUMAN TEETH. around the tooth in almost a straight line. There is frequently a dip rootward on the buccal face. The Root. — A single root normally characterizes the lower first bicuspid although in rare instances two roots are found. When single it is conical, the buccal and lingual sides being uniformly in- clined toward each other and continuing these faces of the crown. The lingual is the narrower, which is caused by the fact that the flat- tened mesial and distal faces converge in passing lingually. These latter are usually slightly con- vex and uniformly taper to the apex, but occa- sionally they are marked with a shallow longi- tudinal depression. The end of the root is sharply pointed and is frequently deflected dis- tally. The cervical portion of the root is oval in cross-section. ^/'^'^- 5?--Ri|ht Lower jj^^ p^ip Cavity.— As in all single rooted First Bicuspid. Cross- ^^ -^ ... section at cervix showing teeth there is no sharp _ division between the pu p cana . ^^^^ chamber and canal (Fig. 49). The cham- ber has one well-defined horn situated beneath the buccal cusp and when a lingual cusp exists there is a small projection of the cavity in its direction (Fig. 50). At the level of the gingival margin the cavity is oval in cross-section whence it continues diminishing in bucco- lingual diameter to the apical foramen (Fig. 51). It is usually small and thread-like in the apical third of the root. THE LOWER SECOND BICUSPID. While this tooth bears a close resemblance to the lower first bicus- pid tooth in many particulars, in some details it is quite different. These latter chiefly pertain to the lingual portion of the occlusal face of the crown and the adjacent surfaces to which this is related. In general the crown of the tooth is smaller and more rounded than the first. Viewed from the occlusal face it will be seen that this surface is larger and even more nearly circular in outline than the first. In some instances this is due to the presence of a well-developed lingual cusp and prominent marginal ridges mesially and distally. In other instances the same rounded outline is caused by the presence of two lingual cusps, a fissure dividing the lingual portion in its center. The buccal cusp is less prominent than that of the first bicuspid, and has a well-defined triangular ridge which seldom unites with that of the lingual cusp. When present the lingual cusp is smaller than and THE UPPER FIRST MOLAR. 3 1 not so prominent as the buccal and is usually separated from it by a mesio-distal groove. This latter terminates in pits, the mesial and distal pits, and is curved lingually. When the face presents three cusps the groove has three branches meeting in a central pit or fossa. The angles of the crown are not well marked. The buccal surface is more rounded and shorter and wider than that of the first bicuspid. The lingual surface is proportionally larger than the lingual of the lower first bicuspid, being longer occluso-gingivally because of the lingual cusp at the base of which it is also wider mesio-distally. The mesial and distal faces of the crown are similar to those of the first bicuspid except that they are wider bucco- lingually and are both slightly more convex. The cervical margin encircles the tooth almost in a horizontal plane, but a curve rootward may usually be made out on the buccal face. The single root is con- ical, proportionately longer than that of the first bicuspid, flattened on its mesial and distal sides, and usually bent distally in its lower portion. The pulp cavity is larger than that of the first bicuspid, the chamber being shaped to correspond with the external surface of the crown and having the rudimentary lingual horn better developed. The canal is oval or circular in cross-section at the cervix from whence it tapers gradually to the apical foramen. THE UPPER FIRST MOLAR. The crown of the upper first molar is roughly cuboidal in shape and offers for examination five surfaces — occlusal, buccal, lingual, mesial and distal. The Occlusal Surface (Fig. 52). — This is irregularly rhomboidal in outline as may be seen when the crown is viewed from this surface. The mesial and distal margins are nearly straight and parallel; the buccal and lingual margins are curved. At the mesio-buccal and disto-lingual juncture of these margins acute angles are formed while the angles at the disto-buccal and mesio-lingual juncture are obtuse. The surface is marked by the presence of four cusps, four marginal ridges, two fossae, and several developmental grooves. The mesial marginal ridge is a rounded and well-defined elevation of enamel extending from the summit of the mesio-buccal cusp to that of the mesio- lingual cusp, and is curved rootward between these points. It is often crossed near its center by the mesial developmental groove which ex- tends from the occlusal to the mesial surface. The buccal marginal ridge unites with the mesial at the mesio-buccal angle of the tooth. It 32 THE ANATOMY OF THE HUMAN TEETH. extends from this point to the point of the mesio-buccal cusp, then in a slightly lingual direction to the bottom of the buccal groove, then buccally to the point of the disto-buccal cusp and then to the disto- buccal angle, being curved latterly in a lingual direction to unite with the distal marginal ridge. It is the sharpest of the marginal ridges, a fact in large part due to the sharpness of the buccal cusps. The distal marginal ridge is similar to the mesial in that it is curved rootward between its terminations and is a rounded ridge of enamel. It is marked to the buccal side of its center by the distal groove, which passes over upon the distal face of the crown. The lingual termina- tion is well rounded and consequently less easily differentiated from the disto- lingual cusp in which it terminates. The lingual marginal ridge completes the periphery of the occlusal surface, ex- tending from the disto-lingual to the mesio-lingual angle of the crown. From its mesial end it curves lingually to the summit of the mesio-lingual cusp, then buccally to the point where it is divided by the disto-lingual cusp and then lingually again to the top of the disto- lingual cusp. It is the most rounded of the marginal ridges. The Cusps. — The upper first molar may be said to possess four cusps nor- mally but in a large number of cases it has five. The mesio-buccal cusp, located near the mesio-buccal angle of the tooth, is sharp and from its summit descend four ridges. These latter are the buccal, which continues upon the buccal surface of the crown, the triangular which descends into the central fossa, and the two ridges descending mesially and distally forming portions of the buccal marginal ridge. The disto-buccal cusp is somewhat smaller than the one just described, but like it is sharp and has four ridges descending from its point. The buccal ridge descends upon the buccal face, the mesial and distal ridges are portions of the buccal marginal, while the fourth ridge unites with one from the mesio-lingual cusp to form the oblique ridge. The disto-lingual cusp is usually the smallest (except the fifth) and is rounded. But two ridges descend from it, one each in a mesial and lingual direction to form the marginal ridge of these boundaries. Its lingual and distal aspects fade off into these respective faces of the Fig. 52. — Left Upper First Molar Occlusal Surface. THE UPPER FIRST MOLAR. 33 crown without demarcation. It is separated from the obhque ridge by the disto-lingual groove. The mesio-lingual cusp is frequently the largest cusp of this tooth. It is much rounded and has ridges descending from it as follows: one to the mesial to join the mesial mar- ginal ridge and one distally forming a portion of the lingual marginal ridge, while one passes in the direction of the disto-buccal cusp, meet- ing a ridge from the latter to form the oblique ridge. The buccal Fig. 53. —Left Upper First Molar. Buccal Surface. Fig. 54. — Left Upper First Molar. Lingual Surface. aspect of the cusp forms a wall of the central fossa, while the lingual side is rounded and descends without demarcation into the lingual surface of the crown, or in teeth with a fifth cusp descends into the groove dividing the latter from the crown. The fifth cusp, or lingual cingule as it is sometimes called, varies much in size and occurrence. When present it is an elevation of enamel on the lingual surface of the crown, near and just distal to the mesio-lingual angle and at the lingual base of the mesio-lingual cusp, from which it is separated by a groove, the mesio-lingual. The FosscB and Grooves. — The central fossa is triangular in shape and occupies the space between the mesio-buccal, disto-buccal and mesio-lingual cusps, its walls being formed by. the central inclines of 3 34 THE ANATOMY OF THE HUMAN TEETH. these cusps and the mesial marginal ridge. In its center is the central pit from which radiate the mesial developmental groove, which passes forward over the mesial marginal ridge to the mesial face of the crown, the buccal groove which divides the mesio-buccal from the disto-buccal cusp and reaches the buccal surface of the crown, and the distal which is less well marked and passes distally over the oblique ridge. Each of these grooves may be the seat of a fault or fissure, the buccal exhibiting it more commonly and the distal less commonly than the others. The distal fossa is smaller than the -central and is located between the disto- lingual and disto-buccal cusps and the distal marginal and oblique ridges. Its longest di- mension is disto-lingually in which direction it is traversed by the disto-lingual groove. This latter has its terminations in the lingual pit near the cen- ter of the lingual surface and a pit in the distal fossa. It is parallel to the oblique ridge, dividing the disto-lingual cusp from this, and is usually the seat of a fissure, the result of faulty union of the develop- mental lobes of the crown. The distal groove passes through this fossa, crossing the oblique ridge anteriorly and the distal marginal ridge posteriorly. The Buccal Surface (Fig. 53). — This is bounded by four margins, of which the occlusal is irregular, sha p and prominent, being formed by the buccal marginal ridge and the two buccal cusps, the cervical is almost straight, while the mesial and distal are not well marked, the distal being less so than the mesial. The two latter are rounded and fade into the respective faces of the crown. They converge from the occlusal surface to the cervix, so that when the tooth is viewed from the buccal face the bell-shape of its crown is noticeable. For the most part the surface is slightly convex having, however, a depres- ion near its center in which is frequently located a buccal pit. The uccal groove divides it into two lobes and usually terminates in the Fig. 55. — Left Upper First Molar. Mesial Surface. THE UPPER FIRST MOLAR. 35 buccal pit, but the depression is sometimes continued rootward and is continuous with that between the two buccal roots. At the cervix there is a ridge of enamel, the cervical ridge, which gives prominence to this line. The Lingual Surface (Fig. 54). — This is somewhat similar in out- line to the buccal, but is narrowed mesio-distally at the cervix as the sides converge to a single root instead of two as upon the buccal surface. The surface is more convex than the buccal, but, like it, is often the seat of a pit near its center, the lingual pit, in which the disto- lingual groove terminates. The depression caused by this groove is often continued rootward, dividing the surface into two lobes, and being continuous with a longitudinal depression upon the lingual root. Th' distal lobe is rounded in every direction, its distal portion be- ing continuous with the distal face of the crown without de- marcation. The mesial lobe resembles this in character ex- cept that its anterior margin is more defined. In those teeth with five cusps this lobe pre- sents near the occlusal margin a rounded cingule, whose lin- gual side is continuous with the lingual face of the crown, but which is separated from the mesio- lingual cusp by a groove, the mesio-lingual groove. This latter often terminates distally by uniting with the disto-lingual groove, but frequently at each extremity it fades away into the surface of the tooth. The cervical line is almost straight, the mesial and distal margins are curved and converge toward the cervix, while the occlusal margin resembles that of the buccal face except that the cusp points are not so sharp and the marginal ridge is more rounded. The Mesial Surface (Fig. 55). — While this is generally convex bucco-lingually near the occlusal margin, in its gingival two-thirds it is either flat or it may be slightly concave. It is either convex or nearly flat occluso-gingivally, and the most prominent point is Fig. 56. -Left Upper First Molar. Distal Surface. 36 THE ANATOMY OF THE HUMAN TEETH. slightly above the occlusal margin where the tooth is in contact with the second bicuspid. The surface is bounded by four margins — the cervical is usually concave in an occlusal direction, while the occlusal is concave in a cervical direction because of the mesial groove which is sometimes continued for a short distance upon this surface. The buccal and lingual margins are convex and converge to the occlusal surface. They are rounded, the former being better defined than the latter. The lingual margin is modified by the presence or absence of the lingual cingule, the location of the notch caused by the mesio- lingual groove varying according to the height of the cingule. The Distal Surface (Fig. 56). — Four sided, this surface resembles the mesial in general outline. It is generally con- vex, except that often the distal groove is continued and makes a slight longi- tudinal depression near its center. The occlusal margin is more deeply notched than that of the mesial surface, the cer- vical line is nearly straight or concave occlusally while the buccal and lingual margins are rounded, the former being less well defined than the latter. The Roots (Figs. 53 and 54). — These are three in number and are named from their location, the mesio-buccal, disto- FiG. s7- — Right Upper First Molar. , ,,,.,,_, Cross-section below cervix, showing buccal and Imgual. They are not given the pulp chamber and entrances to ^ff directly from the basc of the crown, the pulp canals. •' but the division which results in them occurs usually about one-third the distance from the cervix to the root apices. The mesio-buccal root (Fig. 55) is flattened antero-posteriorly, and is next to the lingual in size and length. Viewed from its mesial side, it is nearly equal in width to half the crown and its sides slowly converge to. near its end when they meet in a blunt, rounded point. From this view the root is inclined buccally, while viewed from the buccal side, it is seen to have a mesial inclination in its first third, curving then in a distal direction to its extremity. It is thin and flat mesio-distally. The disto-buccal root (Fig. 56) is the smallest. It is narrower bucco-lingually than the mesio-buccal and is short. Its sides gradually incline to a more or less pointed apex, and it is slightly flattened mesio- THE UPPER FIRST MOLAR. 37 distally. In its first third it is inclined distally, but in the remainder of its extent it is usually inclined mesially, approaching the mesio- buccal root. The lingual root (Fig. 54) is the largest and usually the longest of he three roots. It is somewhat flattened bucco-lingually, and it is either nearly straight or slightly curved, in which latter instance its extremity is inclined buccally. It diverges markedly from the buccal roots in a lingual direction. Viewed from the lingual face the sides of the root are markedly convergent, sloping from the base of the crown to a somewhat rounded apex. This face of the root often pre- sents a longitudinal depression which is continuous with that on the lingual side of the crown. The Pulp Cavity (Fig. 57).— The pulp cavity is easily separable into the pulp chamber and the pulp canals, of which the former is ap- proximately the shape of the exterior of the crown of the tooth, while the latter, which are three in number, correspond to the general external shape of the roots. The pulp chamber is characterized by four horns or depressions in its occlusal wall, one entering each of the four cusps. Its four lateral walls are parallel to the sides of the crown and are generally flat. In bell- shaped teeth they converge from the occlusal wall to the floor (Fig. 58) which is much smaller than the occlusal wall, while in teeth whose crown walls are nearly parallel without constriction at the neck, the lateral pulp chamber walls are similarly disposed. The horns of the pulp chamber are marked and penetrating and often persist in mature teeth as deep recesses in the dentin. The floor of the pulp chamber presents the three openings for the pulp canals. In the young adult tooth these are in the form of funnel-shaped open- ings. As age increases, the size of the pulp chamber decreases. The thickening of the lateral walls encroaches upon the pulp chamber, the Fig. 58. — Right Upper First Molar. Longitudinal section cut through the pulp canals of the buccal roots, showing the pulp chamber and its horns. 38 THE ANATOMY OF THE HUMAN TEETH. funnel-like openings to the canals become simply small apertures and the canals are much reduced in size. The lingual canal (Fig. 57) is the largest and most accessible. It does not conform to the flattened shape of the root but is usually cir- cular, decreasing gradually in caliber to the apex, and following the curvature of the root already noted. The entrance to it is directly under the middle of a line drawn from the summit of one lingual cusp to the other. The mesio-buccal canal (Fig. 58) is next in size and length. The entrance to it is very near the mesio-buccal angle of the tooth, slightly anterior to the summit of the mesio-buccal cusp. It is flat and ribbon-like and follows the curvature of the root. The disto- buccal canal (Fig. 58) is small and thread-like. Its entrance is approx- imately under the disto-buccal cusp. It is short and difhcult to enter. THE UPPER SECOND MOLAR. The crown of this tooth differs from the first molar in any given denture in that it is flattened mesio-distally, with a rounding of the mesio-lingual and disto-buccal angles; its cusps are not so long and their summits are nearer the center of the tooth; it almost never pos- sesses a fifth cusp or cingule, and the disto-lingual cusp is relatively smaller than that of the first molar. The Occlusal Surface (Fig. 59). — When the crown is viewed from the occlusal surface this latter is seen to be rhomboidal in outline but with the angles more rounded than those of the first molar and with the lingual margin almost semicircular. The mesial marginal, the distal marginal, the buccal and the lingual marginal ridges are formed as they are in the first molar. In this tooth Fig. 59. — Left Upper Second ,, ' i , rj^i .^^ :^ Molar. Occlusal Surface. ^^ey are more rounded. The mesio- buccal cusp has four ridges descending from its summit, one each in a buccal, lingual, mesial and distal direc- tion. It is smaller and less sharp than the corresponding cusp of the first molar. The disto-buccal cusp is usually small and pressed in toward the center of the crown by the rounding of the disto-buccal angle. Its buccal ridge is absent or barely distinguishable. The mesio-lingual cusp is usually the largest cusp and is well rounded and without a clearlv THE UPPER SECOND MOLAR. 39 defined point. It has ridges which pass mesially, distally and buccally : the latter is heavy and strong and assists in forming the obhque ridge. The lingual surface of the cusp is much rounded. The dislo-lingual cusp varies much in size and form. It is usually relatively smaller than that of the first molar. Often it is little more than an enlarge- ment of the distal marginal ridge, with which its buccal ridge is contin- uous. Its distal and lingual faces are much rounded. The central fossa is not so deep as that of the first molar, though similarly its walls are formed by the two buccal cusps and the mesio-lingual together with Fig. 6o. — Left Upper Second Molar Buccal Surface. Fig. 6i. -Left Upper Second Molar. Lingual Surface. the mesial marginal and oblique ridges. The mesial groove, the buccal groove and the distal groove all pass from it in these respective directions. It has a pit, the central pit, in its center, and the distal fossa has, simi- larly, the distal pit. From the latter fossa the distal groove passes to the distal surface and the disto-lingual to the lingual surface, ending on the latter usually in the lingual pit. The Buccal Surface (Fig. 60). — This resembles that of the first molar so closely that only their points of difference need to be pointed out. The occlusal margin has the same outline as that of the first 40 THE ANATOMY OF THE HUMAN TEETH. Fig. 62. -Left Upper Second Molar. Mesial Surface. from that of the first molar ex- cept that it is much more con- vex and the fifth cusp is almost never present to modify the form of its mesial portion. The Mesial Surface (Fig. 62). — This resembles closely the cor- responding surface of the upper first molar, but is relatively smaller and is often concave from buccal to lingual side. Its lingual margin is less well de- fined than its mesial. The Distal Surface (Fig. 63) . — Usually more convex than this surface of the first molar, and relatively shorter occluso-gingi- vally, the distal surface of this tooth resembles in other respects molar except that the smaller proportionate size of the disto- buccal cusp causes this portion to be slightly altered. The distal margin is more rounded and less pronounced than that of the first molar, but the other two margins are similar. The buccal groove continues upon the buccal face, from the occlusal surface, some- times to the point of bifurcation of the roots, less rarely ending in a buccal pit. The lobe of the crown mesial to the depression is always larger than the distal lobe. The cervical ridge is not so frequently marked. The Lingual Surface (Fig. 61). — This differs in no wise Fig. 63. — Left Upper Second Moalr. Distal Surface. THE UPPER THIRD MOLAR, 41 Fig. 64. — Right Upper Second Molar. Cross-section at cervix showing pulp chamber. its mesial neighbor. The varying size and portion of ihe disto-lingual cusp influence the exact form of this face of the crown. The Roots. — Alike in number and gen- eral form to those of the first molar, the roots of the second differ in some respects from them. The mesio-buccal (Fig. 62) is flattened antero-posteriorly, the disto- buccal (Fig. 63) is nearly conical, while the lingual root (Fig. 61) is longest, largest and flattened bucco-lingually but seldom ex- hibits the depression observed on this root of the first molar. The two buccal roots have a distinct distal inclination and tend to converge at their apices. The disto- buccal root occupies a position relatively more lingual than that of the first molar because of the flattening of the disto-buccal angle of the crown. The Pulp Cavity. — The differ- ences between the form of this and that of the first molar correspond to the differences in the surface forms of the tAvo teeth. The pulp chamber is flattened mesio-distally (Fig. 64) and the entrances to the canals are rela- tively nearer together and that of the disto-buccal canal is more lingually located. The horns of the pulp chamber are four in number but are smaller and less penetrating than those of the first molar. The root canals have the same shape as those of the first molar but are smaller and more -Right Upper Second Molar. Fig. 65 Longitudinal Section cut through mesio- buccal root canal, showing pulp chamber, difficult tO enter (Fig. 65). THE UPPER THIRD MOLAR. Greater variation occurs in the form of this tooth than in that of any other in the dental series. In its typical form it has only three 42 THE ANATOMY OF THE HUMAN TEETH. cusps, the disto-lingual cusp having disappeared, while in its most strongly developed form this is present but is much reduced in size by comparison with the other cusps of the tooth. Many atypical teeth are observed in which the cusp development is difiScult to classify. A description will be given of the typical tooth. The Occlusal Surface (Fig. 66). — This is marked by the presence of a mesio-buccal, a disto-buccal and a mesio-lingual cusp. The disto- lingual is represented only in the distal marginal ridge, or may be en- tirely absent when the oblique ridge forms the posterior margin of the surface. The buccal cusps are like in form to those of the first and second molars except that they are shorter and smaller. The mesio- FlG. 66.— Left Upper Third Molar. Occlusal Surface. Fig. 67. -Left Upper Third Molar. Buccal Surface. lingual cusp is large and rounded and the central fossa is well defined ; usually many small ridges descend from the cusps into it. The mesial marginal ridge is well defined, the buccal depends in character upon the buccal cusps and the lingual is usually poorly discernible. The posterior margin may be either formed by the triangular ridge or the distal marginal ridge may be present. The Buccal Surface (Fig. 67). — In typical teeth this resembles the buccal face of the second molar but is smaller in extent, more rounded, and its distal lobe is poorly defined. The Lingual Surface (Fig. 68). — Variations in the form of this surface are caused by the presence or absence of the disto-lingual cusp — when present, this cusp surmounts a lobe of this surface which is partially divided from the mesial lobe by the disto-lingual groove. In this event the mesial lobe resembles that of the second molar but THE UPPER THIRD MOLAR. 43 is even more convex. When the lingual side is surmounted only by one cusp, it is much rounded and convex and joins the mesial and distal faces almost without line of demarcation. The Mesial Surface (Fig. 69). — This resembles that of the second molar in being flat and sometimes concave from buccal to lingual sides, but it is smaller in extent of surface. The Distal Surface (Fig. 70). — While it is usually rounded from buccal to lingual side, being always so when the disto-lingual cusp is absent, this surface may also be flat or even concave, when the crown has four cusps. It is always smaller in area than the mesial surface or than the distal surface of the first and second molars. Fig. 68. -Left Upper Third Molar. Lingual Surface. Fig. 69. — Left Upper Third Molar. Mesial Surface. The Roots. — These vary much even in teeth which are typical in regard to their crowns. There are sometimes three roots, a mesio- buccal, a disto-buccal and a lingual, which are usually short and have a distal and a lingual curvature. These are sometimes fused together throughout most of their length. Occasionally only one root is seen caused by the complete fusion of the roots. Occasionally also four roots may be found (Fig. 71). The Pulp Cavity. — The external form of the crown largely deter- mines the form of the pulp cavity, so that in trituberculate teeth this cavity is triangular in cross-section while in quadriluberculate teeth, it has the general form of the pulp chamber of the other upper molars. Its lateral walls converge more to the floor of the pulp chamber which is situated at a higher level than that of the pulp chamber of the second molar. The horns of the pulp chamber are less well defined and are 44 THE ANATOMY OF THE HUMAN TEETH. shorter than those of the other upper molars and correspond in number to the number of cusps in any given tooth. The pulp canals usually correspond in number with the number of roots except that in teeth in which the roots have fused into a single one, there may be three or even four root canals, which sometimes have separate apical fora- mina, or again may unite before this is reached and have a common Fig. 70. — Left Upper Third Molar. Distal Surface. " Fig. 71.— Left Upper Third Molar. With roots not completely developed and atypical in having four roots. Shov/ing large patulous openings into root canals. termination. Occasionally in the single rooted tooth there is only one large canal, the walls of which are continuous with those of the pulp chamber and converge to a small foramen at the root apex. Where more than one canal exists, they are small and thread-like, quite short as the roots are short, and the openings from the pulp chamber into them are very close together. THE LOWER FIRST MOLAR. The largest tooth of the human series is the lower first molar, which is longer mesio-distally than the upper first molar, and is of about equal width. The five surfaces of its crown may be described. The Occlusal Stir face (Fig. 72). — This is irregularly trapezoidal in outline, its four margins usually being rounded. The buccal and lingual are more convex than the mesial and distal which may be al- most straight. These latter converge toward the lingual side in consequence of which this is shorter than the buccal. Five cusps are usually present, three upon the buccal side and two upon the lingual. A central fossa is formed and occupies nearly the center of the surface and from this radiate grooves separating the cusps. Four ridges THE LOWER FIRST MOLAR. 45 bound the surface. The mesial marginal ridge is the best defined of these. It passes from the mesio-buccal to the mesio-lingual angle of the crown, is concave rootward and is usually crossed near its center by the mesial groove. It is continuous at its buccal and lingual ex- tremities with the marginal ridges of these names. The buccal marginal ridge is poorly defined, is bowed in a buccal direction, and is made up of the ridges descending mesially and distally from the three buccal cusps. The distal marginal ridge is not so prominent as the mesial but is like it in other respects. It is commonly crossed by the distal groove. The lingual marginal ridge is made up of the ridges descending ante- riorly and posteriorly from the two lingual cusps. It is cut near its center by the lingual groove and is somewhat sharper than the buccal marginal ridge. The mesio-buccal cusp is usually the largest and some- times the longest cusp of this tooth. It is a rounded elevation with ridges descending mesially, buccally, and distally, and some- times two or more toward the central fossa from its lingual sides. The names of these ridges correspond to the direc- tion in which they descend from the point of the cusp, except that the lingual ridge is usually spoken of as the triangular. It is the most sharply defined of all. The buccal cusp is next in size of the buccal series of cusps, being intermediate in size and position between the mesio-buccal and the disto-buccal cusp. It has also four ridges which pass in a buccal, lingual, mesial and distal direction respectively. The lingual ridge descends into the central fossa and is called the triangular ridge. The disto-buccal cusp is separated from the last described cusp by the disto-buccal groove. It varies in size and position. It is more prominent buccally where it is of greatest size, but when found of small size -it is located nearer the distal face of the tooth and there is a corresponding increase in the size of the buccal cusp. The disto-buccal is always the smallest cusp. Three ridges, a mesial, a distal and a triangular, may usually be observed, but its buccal surface is rounded and convex. The lingual cusps are sharper than the buccal cusps. The mesio- FiG. 72. — Right Lower First Molar. Occlusal Surface. 46 THE ANATOMY OF THE HUMAN TEETH. lingual is sharp and prominent in the unworn tooth and its summit is near the mesio-lingual angle. Its lingual surface is continuous with that of the crown but ridges descend mesially, distally, and buccally. The triangular ridge passes into the central fossa and ter- minates at the mesial groove opposite the triangular ridge from the mesio-buccal cusp. These two ridges are separated from the mesial marginal ridge by a shallow depression running bucco-lingually. The disto-lingual cusp is usually smaller than the mesio-lingual, Fig. 73. — Right Lower First Molar. Buccal Surface. Fig. 74. — Right Lower First Molar. Lingual Surface. but like it, is pointed and has three ridges descending from its summit, and otherwise resembles it in shape. The central fossa occupies approximately the center of the occlusal surface, and is broad and shallow. The mesial and distal marginal ridges and the five cusps contribute to form its walls. The mesial groove passes from it to the mesial surface, the buccal groove is well marked, usually the seat of a fissure, and passes buccally between the mesio-buccal and buccal cusps; the disto-buccal groove, also frequently the seat of a fissure, passes between the buccal and disto-buccal cusps; the distal groove crosses the disto-marginal ridge and the lingual groove THE LOWER FIRST MOLAR. 47 passes between the lingual cusps, although in some instances it is very poorly marked. The floor of the central fossa is flat and frequently small tubercles of enamel are found divided from each other by fine grooves. The central pit, a fault in the enamel, is usually found where the buccal and lingual grooves meet and a distal pit often at the occlusal termination of the disto-buccal groove. The Buccal Surface (Fig. 73). — This is trapezoidal in shape, and is convex mesio-distally and occluso-gingivally. The mesial and distal Fig. 75. — Right Lower First Molar. Mesial Surface. Fig. 76. — Right Lower First Molar. Distal Surface. margins are much rounded and ill defined, the occlusal margin is marked by three elevations, the cusps, and two grooves, and the cer- vical is usually convex rootward and marked with a prominent ridge of enamel, the cervical ridge. The buccal groove crosses the surface a little mesial to its center and, decreasing in depth, is continuous with the depression caused by the bifurcation of the roots, or it terminates half way between the occlusal and cervical margin in a well-defined de- pression, the buccal pit. The disto-lingual groove is less deep at the occlusal margin and 48 THE ANATOMY OF THE HUMAN TEETH. terminates by disappearing about half way from the cervix. These grooves divide the buccal surface into lobes of which the mesial is most strongly marked, the central and distal being more rounded and usually uniting at the cervical portion, being separated at their occlusal portion by the disto-buccal groove. The Lingual Surface (Fig. 74). — This is convex in all directions but is less so occluso-gingivally than the buccal because of the sharp- ness of the lingual cusps. Its mesial and distal margins are much rounded and converge to the cervical which is convex rootward. The occlusal margin is marked by the two cusps and the lingual groove. The latter is often poorly marked although it is occasionally deep but usually disappears about the center of the surface, and the division of this surface by it into two lobes is not usually distinct. The Mesial Surface (Fig. 75). — While it is generally convex and usually so near the occlusal margin where it affords a point of contact with the second bicuspid, this sur- face is sometimes flat and usually a concavity may be noted near the cervical line. The occlusal margin is notched by the mesial groove between the two mesial cusps, the ateral margins are rounded and convex in an occlusal direction. The Distal Surface (Fig. 76). — This resembles the mesial face of the crown in outline, but is more convex. Its cervical and lingual margins are like those of the mesial but the varying size and position of the disto-buccal cusp determine the occlusal and buccal margins. The latter is rounded and the former is marked by the distal groove. These unite at the disto-buccal cusp, the position of which determines whether the occlusal margin is long or short. The Roots. — There are two roots (Fig. 73), named from their posi- tions, mesial and distal. They are both broad and much flattened mesio-distally. The point of bifurcation is about one-fourth the dis- tance from the cervix to the root apices. The mesial root when viewed from the mesial surface (Fig. 75) is seen to be flat, its sides converging but slightly to a blunt apex. On both its mesial and distal surfaces a longitudinal depression running the length of the root may be ob- served. The mesial and distal sides are nearly parallel until the apex Fig. 77. — Right Lower First Molar. Cross-section at cervix, showing the pulp chamber and entrances to the pulp canals. THE LOWER SECOND MOLAR. 49 is reached. The root is curved mesially so that its lower third has a decided distal turn. The distal root is usually straight and is flattened also mesio-distally. It is not marked by longitudinal depressions on its mesial and distal sides, terminates in a sharper apex than the mesial root, and is not so long. The Pulp Cavity.— The chamber corresponds in general to the shape of the crown, being quad- rilateral in horizontal cross- section (Fig. 77). The occlusal wall of the chamber in young teeth has five horns which are in relation with the five cusps, but these are very poorly marked because of the shortness of the cusps. The lateral walls are four in number, the buccal wall being of greatest extent. These converge to the floor (Fig. 77) which is concave bucco-lin- gually and convex mesio-distally. The buccal and lingual walls meet in a trough- like depres- sion which dips down anteriorly and posteriorly to the entrance into the pulp canals. In any but old teeth the mesial and distal walls (Fig. 78) are contin- uous with the walls of the pulp canals. The openings to the latter are funnel-like. There Fig. 78. — Left Lower First Molar. Mesio- distal longitudinal section cut through the buccal cusps and the pulp canals, showing pulp chamber and canals. are usually two canals in the mesial root which are fine and thread- like and round. They occasionally meet before the apex of the root is reached and terminate in a common foramen although they usually make exit by separate foramina. The distal pulp canal is larger and ovoid in cross-section and easily entered. THE LOWER SECOND MOLAR. The crown of the lower second molar differs from that of the first in that it has four cusps of nearly equal size instead of five. In other particulars its surface form is very similar. The Occlusal Surface (Fig. 79). — The occlusal surface presents 4 50 THE ANATOMY OF THE HUMAN TEETH. for examination four cusps of nearly equal size, situated near its four angles. The summits of the cusps are nearer the center of the crown than are those of the first molar and are more rounded. The out- line of this surface is more rounded than that of the first molar, the mesial and distal margins being of equal length and convex. The buccal and lingual are also usually of equal length but in some instances that of the former is greater. The mesial and distal marginal ridges are similar to those of the first molar, and the surface has a central fossa from which a mesial, distal, buccal, and lingual groove pass to these respective borders. The central fossa is well defined but shallower than that of the first molar. The triangular ridges from the cusps are well marked and between these the grooves meet forming a cruciform sulcus. Occasion- ally the tooth has five cusps when the anatomy of this sur- face is similar to that of the first molar. The Buccal Surface (Fig. 80). — This has the same general form of that of the first molar, but is less complicated because of the absence of the fifth cusp. It is more convex than that of the first molar, is relatively Fig. 79--Right Lower Second Molar. smaller in extent ahd is not so Occlusal Surface. definitely divided into lobes by the buccal groove. This latter usually terminates by blending with the buccal surface about its center and rarely terminates in a buccal pit. The Lingual Surface (Fig. 81). — Except that it is smaller, this resembles the lingual face of the first molar crown so closely as to require no separate description. The Mesial Surface (Fig. 82). — This is more convex than that of the first molar but is like it in other respects. The Distal Surface (Fig. 83). — The absence of the fifth cusp is responsible for the dissimilarity between this and the distal surface of the first molar. It resembles, however, the mesial surface of the second molar, being slightly more rounded. The Roots. — These are two in number and closely resemble the roots of the first molar. They are not quite so long, do not exhibit the longitudinal depressions seen upon the roots of the first molar, THE LOWER SECOND MOLAR. 51 Fig. 80. -Right Lower Second Molar. Buccal Surface. Fig. 81. — Right Lower SecondMolar. Lingual Surface. Fig. 82. — Right Lower Second Molar. Mesial Surface. Fig 83. — Right Lower Second Molar. Distal Surface. 52 THE ANATOMY OF THE HUMAN TEETH. terminate in sharper apices and are usually inclined to the distal at their extremities. The Pulp Cavity (Fig. 84). — The occlusal wall of the pulp chamber has only four rudimentary horns, the floor of the chamber is smaller and the openings into the pulp canals are closer together but in other particulars this is similar to the chamber of the first molar. THE LOWER THIRD MOLAR. No tooth in the human denture is subject to greater variation than the lower third molar. The form most commonly found is that with four cusps, in which instance the crown much resembles the second molar. Rarely it is possessed of five cusps, being somewhat similar to the first molar in form. Often its occlusal surface is much broken up and exhibits a fossa surrounded by a number of cusps and is nearly circular in outline. The Surfaces. — When four cusps are present, and this is the commonest form, the occlusal surface resembles that of the second molar except that the cusps are shorter, the fossa is shallower and the outlines of the sur- face are more rounded. When several cusps exist the grooves separating them radiate from the central fossa. The buccal, lingual, mesial and distal sur- faces resemble those of the second molar if the tooth has four cusps, or those of the first if it has five. In other forms of the tooth the tendency to roundness of these surfaces is to be noted and it is usually difficult to perceive any line of demarcation between them. The Roofs. — There are two which usually resemble the other lower molar roots except that they are shorter in proportion to the size of the crown, and generally have a marked distal curve which complicates the extraction of the tooth. Often the roots are fused and sometimes throughout their whole extent, giving thus only one actual root. The Pulp Cavity. — It can only be said concerning this that the chamber corresponds to the external form of the crown, being similar to this cavity of the first or second molar according as the crown re- FiG. 84. — Left Lower Second Molar. The roots have not been completely developed. Longitudinal section through mesial root showing pulp cavity and method of its division into two pulp canals. THE DECIDUOUS TEETH. 53 sembles one or the other of these teeth. In other instances it is usually a rounded cavity resembling the external form of the crown. The pulp canals are similar in number to those of the first molar and may be found separated even if the roots of the tooth are fused. In rare instances a single large canal terminating in a single small apex is found. THE INTERPROXIMAL SPACES. The relationships of the various portions of the incisal and occlusal surfaces of the teeth in the occlusal position of the mandible are de- scribed in the chapter on Orthodontia to which the reader is referred for details. Figs. 85 and 86 illustrate the teeth in occlusion. Ex- amination of these figures will show that each tooth is also in contact ■with the teeth which adjoin it on either side at a point about one-third the distance from the incisal or occlusal surface to the gingival mar- gin. This is spoken of as the "point of proximal contact." It will be observed that a triangular space exists between this point and the margin of the alveolus, which is known as the interproximal space. In the young subject this space is almost wholly filled with the soft tissue of the gum which extends nearly up to the proximal contact points, but as age advances the sharply defined margin of the alveolus becomes blunted and the gum tissue recedes so that in late adult life this space is normally more incompletely filled. The normal proxi- mal contact of the human teeth (man being the only animal with no diastema in the denture) protects the gum tissue between the teeth and the adjoining gingival attachment from injury during the mastication of hard food. Wherever caries has destroyed this proximal contact or where it is wanting from other cause there is danger of wounding the gum and pericementum in the proximal space by the wedging of food of a fibrous character between the teeth, with the subsequent for- mation of pockets between the free margin of the gum and the tooth root. The food wedged into this space can only be removed by some mechanical means and the difficulty increases as time goes on. If allowed to remain its fermentation is attended with the added chem- ical and bacterial irritation of the tissues and the carious process is further favored From these facts will be easily seen the necessity for the present practice in operative dentistry or in crown and bridge- work for a complete reestablishment of the proximal contact points in all such restorative procedures. THE DECIDUOUS TEETH. The temporary or deciduous teeth serve for purposes of masti- cation during the earlier years of life and are exfoliated between the 54 THE ANATOMY OF THE HUMAN TEETH. fifth and the twelfth years to give way to their permanent successors. They are less highly developed for functional purposes than the per- manent teeth but entirely satisfy the requirements of the food habit of these early years. They are necessarily smaller than the permanent teeth and are but twenty in number. They resemble in many respects the permanent teeth as regards external form and internal anatomy, but differ in some particulars and these latter must be pointed out. They are in general less well I'lG. 85. — The permanent teeth in occlusion. External View. (American Text-book of Prosthetic Dentistry.) developed as to surface markings. They have relatively longer roots but these are relatively smaller than those of the permanent teeth. This latter fact accounts for the constricted neck and bell-shaped crown characteristic of the deciduous teeth. The crowns of the teeth are shorter in relation to their width than are those of the permanent teeth. The Upper Central Incisor (Fig. 89). — In addition to being much smaller than the permanent central incisor, the crown of this tooth is less well marked upon its surface. The labial grooves, the lingual marginal ridge and fossa and the distal angle are especially lacking in development. Its surfaces are much rounded and its neck is con- THE DECIDUOUS TEETH. 55 stricted. The root is relatively longer and smaller than that of the permanent tooth but resembles it in other particulars. The Upper Lateral Incisor (Fig. 89).— This resembles both the permanent lateral and the deciduous central incisor. It has the characteristics of the former except in a modified degree. Its surface markings are less pronounced than are those of the permanent lateral and it resembles the deciduous central except that its width is less and its distal angle is more rounded. It is a more delicately shaped tooth but is usually equal in the length of its crown to the central and fre- quently its root is longer. The latter resembles that of the permanent Fig. 86. — The Occlusion of the Teeth. Lingual View. (American Text-book of Prosthetic Dentistry.) lateral incisor in other particulars except of course that it is relatively smaller. The Upper Cuspid (Fig. 89). — The resemblance between this tooth and that of the permanent series is marked, but sufficient differences exist between them to easily differentiate the two teeth. The crown of this tooth is proportionately shorter and more rounded than that of the permanent cuspid. The labial surface presents a marked labial ridge ascending from the point of the cusp, and the labial grooves are much nearer the angles of the tooth. The angles 56 THE ANATOMY OF THE HUMAN TEETH. of the crown are much nearer the cervical line than those of the per- manent cuspid in consequence of which the mesial and distal cutting edges are relatively longer and the mesial and distal surfaces are smaller. The lingual surface has a marked lingual ridge and the surface is generally rounded and convex. The root is proportion- ately smaller than that of the permanent cuspid and the pulp canal is small in consequence, but the pulp chamber, like that of all the deciduous teeth, is relatively large. The Upper First Molar.— The molar teeth of the deciduous series are totally unlike their successors, the bicuspids, and partake chiefly of the characteristics of true molar teeth. The crown of the first upper molar usually has three cusps, two on the buccal and one on the lingual side. (Fig. 87.) The surface is almost quadrilateral because the large size of the lingual . cusp serves to balance the two buccal on the opposite side. The corners of the figure are much rounded, the sharpest corner being the mesio- FiG. 87.— Occlusal surface of the upper buccal while both the lingual deciduous teeth. corners are much rounded. The buccal cusps are sharper than the lingual which is full and rounded, although all are more pointed than those of the upper per- manent molars. A central fossa occupies the space between the cusps. It is broad and shallow. A groove passes from it to the buccal, mesial and distal sides respectively, and these serve to separate the cusps from each other. The buccal surface resembles that of the upper molars except that the occlusal margin is sharp, the surface is more rounded, the buccal groove is very shallow and poorly defined, and at the cervical margin a ridge of enamel passes from the mesial to the distal border. The lobe of 'this surface mesial to the buccal groove is proportion- ately larger than that of the permanent molar, as it is both wider and larger from occlusal to cervical margin than the distal lobe. The lingual surface is full and convex in every direction and passes into the mesial and distal faces without demarcation. These latter resemble those of the upper permanent molars, the mesial being flattened with a convexity near the occlusal margin, the distal being rounded. THE DECIDUOUS TEETH. 57 Three roots are possessed b}' this tooth. They are mesio-buccal, disto-buccal and lingual. The buccal roots are flattened mesio-distally, the lingual being flattened bucco-lingually, and they diverge mark- edly in order to give a space for the permanent tooth which succeeds and which occupies for a time the space between the roots. The pulp chamber is rounded and large, corresponding with the general external form of the crown. The root canals are small and thread-like and difficult to enter. The Upper Second Molar (Fig. 89). — This tooth is larger than the first temporary molar and resembles the first permanent^molar so exactly that a separate description is unnecessary. It seldom has the Fig. 88. — Skull showing deciduous teeth in occlusion. lingual cingule or fifth cusp, it is smaller, more constricted at the neck and its roots are widely separated at their apices, but in other particu- lars the description of the permanent tooth will suffice. The Lower Central Incisor. — Except for the fact that the tooth is smafler, has more rounded angles, and has its labial and lingual grooves poorly defined, the description of the permanent tooth would equaUy apply to this. It must be added, however, that its root is relatively smaller than that of its successor. The Lower Lateral Incisor. — The resemblance between this and the upper deciduous lateral incisor is marked. It is wider than the lower central and its distal angle is rounded like that of the upper lateral. Its various surfaces and its root are like those of its upper opponent and further description is unnecessary. 58 THE ANATOMY OF THE HUMAN TEETH. The Lower Cuspid. — The upper and lower deciduous cuspids are much alike. The latter is narrower mesio-distally and its surfaces are not quite so convex but in other particulars its anatomy is identical with that of the former. The Lower First Molar (Fig. 89). — This tooth has the general molar form but a detailed description is necessary for its identifica- tion. Its crown is a much rounded cuboid and exhibits four cusps, one near each of its rounded angles. On the occlusal surface these four cusps are seen to be divided by grooves which unite in the fossae. The mesio-buccal cusp is the largest. A ridge descending from it Fig. 89. — Dissected specimen of maxillae and mandible showing the deciduous teeth. anteriorly curves and meets one from the mesio-lingual cusp to form a mesial marginal ridge. Triangular ridges from these two cusps meet at the bottom of a mesial groove, and a small depression is formed between these and the mesial marginal ridge. This is often called the mesial fossa but is very small as compared to the distal fossa which is located between the two distal cusps and these triangular ridges. A distal, a buccal and a lingual groove, all poorly defined, emanate from the distal fossa in these several directions. The buccal and lin- gual grooves are not continuous because the greater size of the mesio- buccal cusp carries the former too far distally. The disto-buccal cusp is small, the mesio-lingual is usually the sharpest and longest, and the disto-lingual is not well defined as the lingual groove is always shallow. The distal marginal ridge is cut by the distal groove. THE DECIDUOUS TEETH. 59 The buccal surface is convex and has near its cervical margin a pronounced ridge of enamel, the cervical ridge. The mesial margin is longer than the distal in consequence of the greater size and length of the mesial lobe, a condition similar to that of the first upper decidu- ous molar. The buccal groove is shallow and either terminates in a pit or disappears upon the center of the surface. The lingual surface is convex, and the lingual groove marks its occlusal portion about the center when it is present but often it is almost indistinguishable on this surface. The mesial and distal sur- faces are very similar to those of the second permanent molar. The mesial is fiat with a pronounced occlusal edge; the distal is more rounded and the distal groove usually marks decisively its occlusal margin. The tooth has two roots which are similar to those of the first permanent molar except that they are smaller and quite divergent to give space for the bicuspid which follows. The pulp chamber cor- responds in shape with the external surface of the crown. The en- trances to the three canals are near together, the two mesial ones being small and very difficult to enter, the distal canal being more accessible. The Lower Second Molar (Fig. 89).— Beside the constriction of its neck, the divergence of its roots, and its smaller size, this tooth resembles the first permanent molar in almost every particular. The description of the latter tooth will apply to the deciduous tooth and the reader is referred to it. CHAPTER 11. THE HISTOLOGY OF THE HUMAN TEETH. BY CHARLES R. TURNER, D. D. S., M. D. A knowledge of the minute anatomy of the tissues of the human teeth is as important as an acquaintance with their surface forms, for it paves the way to an understanding of their several physiological rela- tionships in the tooth, to a knowledge of the pathological conditions arising in them, and to a rational conception of the various operative and therapeutic measures used in the treatment of these conditions. The tissues of the human tooth are the enamel, which is the hard external covering of the crown; the dentin, which composes the bulk of the tooth and largely determines its form; the cementum, which forms the external covering of the root and to which is attached the peri- cementum, a membrane intervening between the tooth and its bony socket in the alveolar process; and finally the dental pulp, a mass of soft tissue occupying the internal chamber of the tooth called the pulp- cavity. A clearer understanding of the relationships of these tissues may be had if we first become acquainted with the method of their develop- ment in the embryo. This also confers a better knowledge of their structure. About the fortieth to the forty-fifth day of intra-uterine life, there is a thickening of the stratum Malpighii of the oral epithelium over the site of the future jaw. This forms a band of epithelial cells extending from one end to the other in each jaw. About the forty-eighth day a budding is seen to take place from the under surface of this tooth-band, and ten rounded buds appear attached to it, marking the beginning of the tooth-germs for the deciduous teeth. These buds dip further into the substance of the underlying connective tissue, and becoming invagin- ated upon their advancing surfaces, finally enclose in this invagina- tion a mass of mesoblastic connective tissue and become the tooth- germs. This epithelial cup which has descended from the mucous membrane remains connected with it for some time by a cord of epithe- lial cells, the epithelial cord, but this cord soon disappears, and the tooth-germ is enclosed by a fibrous membrane developed from the 60 THE ENAMEL. 6i surrounding tissue. The epithelial cup becomes the enamel organ of the future tooth, the connective tissue enclosed by it becomes the dentin organ or papilla. The whole tooth-germ enclosed in its sac is known as the dental follicle. (Fig 90.) The enamel organ takes on the form peculiar to the tooth which it is to assist in forming, and its cells begin to alter in character. Those biG. 90. — Section of upper jaw of human embryo near the seventh month of fetal life, showing development of temporary cuspid. A. Ameloblasts showing beginning of enamel formation. B. Dentin. C. Showing beginning of dentin formation. D. Walls of tooth sac. E. Dentinal papilla. X So- (Williams. Dental Cosmos.) next to the dentinal papilla become columnar in form, those on the ex- terior disappear by atrophy, while the intervening ones are changed from polygonal to stellate cells and become the stellate reticulum. This latter finally almost entirely disappears, leaving however next to the inner columnar layer a small layer of cells which now comes to be known as the stratum intermedium. The inner columnar cells now become enlarged and elongated, their nuclei move to their outer ends 62 THE HISTOLOGY OF THE HUMAN TEETH. and they become the ameloblasts, which are the cells directly concerned with the formation of the enamel. The dentin organ or papilla which occupies the space within the enamel organ, and which is formed from the mesoblastic con- nective tissue, is composed of embryonal connective tissue cells of various kinds; spindle shaped, round, and stellate cells are scattered through its substance, while over its entire periphery there is a layer of specialized club-shaped cells, the odontoblasts, which are specifically concerned in the formation of the dentin. In the development of the tooth, a deposit of dentin initiates the process, a layer of dentin being calcified about the external surface of the odontoblastic layer of the papilla. The function of the odontoblasts in this process is imperfectly made out. It is known that lime salts are deposited about their external processes and that these latter become the dentinal fibrils. Furthermore, as said by Broomell, they are believed to superintend the dentin formation, but just what is their rela- tion to the deposition of the lime salts is not known. After the dentin cap is begun it grows by additions to its interior, while upon its periphery enamel formation begins. This is by a process of secretion in which globular masses of calco-globulin are formed in the ameloblas- tic cells; these escape from the external ends of the ameloblasts and, becoming packed together one after another, form the enamel prisms. An albumen-like substance, according to Williams, is secreted in the stratum intermedium, and flows about the partially formed prisms, " supplying the cement substance and probably the mineral matter for the calcification of the whole." Cementum is formed upon the completed dentin root of the tooth by specialized odontoblastic cells, the cementoblasis, which have devel- oped in the wall of the tooth follicle. Its growth is similar to that of subperiosteal bone. The pulp is what remains of the dentin papilla, after the latter has been reduced in size by the growth of the dentin walls. The periph- eral layer of odontoblasts persists during the life of the pulp, but after the mature tooth is formed, these cells remain inactive unless called into activity by some pathologic stimulation from without. THE ENAMEL. The enamel constitutes the external covering of the crowns of the teeth. It is by far the hardest of the animal tissues and for this reason it is particularly suited to resist the wear incident to the use of the teeth in the comminution of food. Its distribution over the crown THE ENAMEL. 63 of a tooth is not uniform, as it is thinnest at the cervical margin, where it is slightly overlapped by the cementum; from this margin it increases in thickness, until over the cusps and cutting edges of the teeth, where it is most exposed to wear, it is thickest of all. It is also slightly thicker at the site of the elevations and ridges upon the crowns of the teeth. In the newly erupted tooth it is faintly and dehcately ridged transversely, and in some teeth it presents other evidences of its develop- ment, but it soon wears smooth and lustrous. When a tooth is erupted the enamel is entirely completed over the whole of its crown. No portion of the tooth is erupted until the enamel covering it is fully formed. When once formed enamel is a fully completed substance, and no physiologic change in its structure or composition ever occurs thereafter. Williams remarks, "Enamel is a solid mineral substance, and the finest lenses reveal not the slightest differences between enamel ground moist from a living tooth, and that which has laid in the earth for a hundred centuries." Defects in the structure of the enamel, in consequence of which the value of its protective office is lessened, are commonly observed at the site of the fissures and pits upon the surface of the tooth-crown which marks the points of union of the several centers from which calcification began. These faults are frequently found in the sulci of the molar and bicuspid teeth, in the buccal pits of the molar teeth, and in the lingual fossae of the upper lateral incisors. These defects are favor- able sites for the beginning of caries, the break in the integrity of the enamel affording lodgment for the bacteria and a favorable starting point for their activity. While enamel is formed in an organic matrix, not the least trace of this remains chemically in the completed enamel. This accounts for the lack of sensitivity of this structure, for it is not capable of trans- mitting physiologically any sensations whatever. These facts demon- strate its value as a vital protective covering for the teeth. Chemically it consists chiefly of the phosphate and carbonate of calcium as the following analysis by von Bibra shows: Man. Woman. Calcium phosphate and fluorid, 89.82 81.63 Calcium carbonate, 4-37 ^-^^ Magnesium phosphate, 1.34 3-55 Other salts 88 .97 Cartilage, 3-39 5-97 Fat, 20 a trace Organic, 3 59 5-97 Inorganic 96.41 94-o3 64 THE HISTOLOGY OF THE HUMAN TEETH. Charles Tomes has shown that the organic matter obtained in this and the older analyses is simply the water which is combined with the lime salts. He has proven that it will be suddenly given off upon ignition of the specimen under analysis. Enamel is not a homogeneous mass of calcified tissue but, under the microscope may be seen to consist of a collection of prisms or rods, Fig. ""9 1. — Section of enamel of human tooth near line of dentin. Shows enamel rods in cross- and longitudinal section. X 1000. (Williams. Dental Cosmos.) five and six sided, which are united together by means of a cementing substance. (Fig. 91.) As it contains no organic matter whatever and has resulted from the completed calcification of the matrix in which it is formed, we find no chemical remains of the matrix, but the tissue exhibits structural evidences of its mode of formation. Generally speaking the enamel rods are arranged so that they begin at right angles to the surface of the dentin, from which they extend to the external surface of the tooth. In the cervical region they incline somewhat THE ENAMEL. 65 downward in the direction of the root, but as the lower third of the crown is reached they pass horizontally outward, becoming more in- clined occlusally as the cusps and the cutting edges of the teeth are reached, in which positions they are largely parallel to the long axis of the tooth. (Fig. 92.) The ends of the prisms are thus exposed to the wear of these surfaces. While a majority of the rods extend from dentin to surface, it will be seen that as the surface area of the latter is greater than that of the former, and as the rods are practically of the same diameter at each end, Dentin. Enamel Fig. 92. — Section showing dentino-enamel juncture, the direction of the enamel rods and primary curvatures of dentinal tubules. (Broomell.) additional rods are required to fill in the interspaces in this fan-like arrangement. These additional rods begin between the other long rods and extend outward toward the surface of the tooth. While the rods pursue in general an almost straight course, in all instances they are slightly curved and in some cases they are much contorted and twisted, and when this is marked the enamel is usually spoken of as "gnarled." The rods are not of uniform diameter throughout their whole ex- tent, as each rod presents a number of varicosities which increase its size. (Fig. 93.) These varicosities vary in different specimens of en- amel but they are present in all. The enlarged portion of one rod is opposite to that of the adjacent rods, and they do not alternate as 5 66 THE HISTOLOGY OF THE HUMAN TEETH. would seem the more natural arrangement. The reason for this is the fact that the globules, of which the rods are made and which are responsible for the varicosities, were deposited simultaneously. The varicosities do not as a rule appear so pronounced in the enamel next the dentin, but elsewhere in any given specimen they are of about uni- form occurrence. The space between the rods is filled in with a more transparent but not more highly calcified cement substance. Wil- liams has shown a specimen in which the globules composing the rods do not appear continuous but seem united with this cement substance as the rods are united to each other. It is very probable that this is Fig. 93. — Enamel rods showing varicosities and striie of Retzius. A. Brown striae of Retzius. B. Enamel rods showing varicosities. X 200. (Williams. Dental Cosmos.^ due to the refraction of the light by the rod substance, as longitudinal sections of the rods normally exhibit under the microscope a series of light bands, the so-called " striation" of the rods, which may be brought into view or made to disappear by slightly changing the focus and were formerly believed to have some structural significance. Another appearance presented by the enamel rods under the micro- scope is illustrated in Fig. 94. In this it will be seen that bands of darker enamel alternate with those of lighter, thus dividing it into strata. This stratification of the enamel is due to the fact that small quantities of pigment have been laid dov^^n at various stages in its development, and they simply mark the exterior of the crown at the time they were laid down. They are in reality incremental lines and mark successive stages in the growth of the enamel. They are usually spoken of as the THE ENAMEL. 67 "brown striae of Retzius. " They begin at the summit of the already formed dentin and extend in curves toward the cervix. The addition of more dentin at the developing end of the tooth gives more surface for enamel to be deposited upon, and another stratum of enamel is formed covering the already formed enamel. The enamel formation at the occlusal end of the crown is completed before that at the cervix. Fig. 94. — Longitudinal section of human enamel showing globules, light. X 3°°- (Williams. Dental Cosmos.) Polarized These facts explain why the incremental lines are neither parallel to the external surface nor to that of the dentin. The "lines of Schreger" are another characteristic of fully formed enamel. They are not visible by transmitted light but can be seen by reflected light as Fig. 95 shows. They are said to be due " to the various directions assumed by the contiguous groups of enamel rods. " * The physical characters of enamel, which are interesting from ♦Broomell: Anatomy and Histology of Mouth and Teeth, 1902, p. 395. 68 THE HISTOLOGY OF THE HUMAN TEETH. the Standpoint of filling operations upon the teeth, are more readily un- derstood when they are viewed in the light of the histology of the tissue. Mature enamel forms a hard covering for the crowns of the teeth which will resist a large amount of force upon it. The enamel rods fit closely together and the intervening tissue is highly calcified and binds them together. Thus they give each other lateral support, and unless there is a break in the enamel surface, it is very difficult to fracture or crush them. In addition, their inner ends rest upon the dentin, a slightly elastic tissue, which gives them a firm support. It is upon these two facts that the ability of the enamel to resist physical force "' ^^> / ,^ --'^ V^ -J^^^ mk. Srownjstria; of Retzius. ^H^ W '■Ik^ ':^^^^H ' Lines of f Schreger. 1 ^^^m w ^^^M ^ Enamel. Dentin. Fig. 95. — Section showing striae of Retzius or incremental lines of the enamel and the lines of Schreger. (Gysi. Broomell.) largely rests. If, however, there is a break in the enamel surface, then it is an easy matter to split off the enamel rods immediately adjacent to the break, and especially is this true if the enamel so split is not sup- ported upon mechanically sound dentin. While the enamel is intrin- sically of a high degree of hardness, yet it has a natural cleavage, and the line of this is along the interprismatic substance, so that the line of cleavage is approximately parallel to the direction of the prisms. Occasionally it breaks transversely through a prism here and there, but never along the central axis of the prism. The lesson these facts teach in the preparation of cavities for filling operations is that the en- amel at their margins must be supported upon dentin, and that these THE DENTIN. 69 margins must be formed so that no prisms which do not reach the dentin are allowed to remain. This requires that the cavity margins be beveled at the expense of prisms which are firmly seated upon the den- tin, and a knowledge of the direction of the enamel prisms is neces- sary in preparing the cavity margins. Black* has shown that enamel possesses less strength than the dentin, as to resistance to both tensile and crushing strains. Therefore the retentive portions of cavities should be made in the dentin, and the mechanical force used in the insertion of gold fillings should be slight upon enamel margins. He has also shown that where several thick- nesses of gold were placed between the instrument and the enamel, that the crushing effect of impact is greatly reduced. THE DENTIN. The dentin composes the bulk of the tooth, and contributes to its form and strengT;h. It surrounds the pulp and protects this from injury, it gives support to the enamel covering the crown, and upon its root por- tion is deposited the cementum which affords attachment to the retentive tissues of the tooth. Normally no part of it appears upon the external surface of the tooth, and when here present is exposed from some error in the development of the tooth or from some break in the enamel or cementum. It is light yellow in color, although it varies slightly in shade in different specimens, and it has somewhat the appearance of ivory or bone. Histologically it is a highly developed connective tissue, and con- sists of a partly calcified organic matrix traversed by a system of tubules, the contents of which is protoplasmic in character. As it is impossible to remove the contents of the tubules no chemical analysis has been obtained of the matrix proper. Von Bibra gives the following as the constituents of a specimen of thoroughly dried dentin: Organic matter (tooth cartilage) 27.61 Fat, 0.40 Calcium phosphate and fluorid, 66.72 Calcium carbonate, 3.36 Magnesium phosphate, 1.08 Other salts 0.83 When the tissue is decalcified by the use of strong acids, the re- maining organic matrix yields gelatin on boiling, while that portion immediately surrounding the tubules which differs from the body of the matrix in resisting strong acids and alkalies, yields elastin on boiling *The Dental Cosmos, Vol. xxxvii, page 414. 70 THE HISTOLOGY OF THE HUMAN TEETH. (Noyes). Opinion differs as to whether this is more highly calcified than the surrounding matrix. Under the microscope it has a dififerent refractive action upon light as the accompanying high-power field shows (Fig. 96). These are known as "//zg sheaths 0} Neumann," and sur- round the protoplasmic contents of the tubules. The matrix itself is practically structureless and homogeneous in character. The tubules traverse it from the pulp-cavity, to the external surface of the dentin. (Fig. 97.) They begin by a funnel-like opening in the pulp-cavity wall, and extend in curves outward to near the surface of the dentin where they usually branch and anastomose freely. They are of practically uniform caliber from beginning to end, Fig. 96. — Dentin showing tubules in cross-section. Dt. Dentin matrix. S. Shadows of sheaths of Neumann. (Noyes. Operative Dentistry.) Dentinal tubules. D. American Text-hook of and as the external surface-area of the dentin is greater than that at the pulp-cavity, the tubules are closer together at their beginning from the latter than at the external surface, and diverge almost imperceptibly in passing outward. They exhibit long graceful curves in their course outward. In the crown of the tooth the tubules exhibit what have been designated their primary and secondary curvatures. The tubules be- gin at right angles to the surface of the pulp, and reach the surface of the enamel at a right angle to it. Between these points they present a reversed curve or ogee. The secondary curvatures are perceptible throughout the extent of the tubule and are due to the fact that the tubule has a general spiral direction through the dentin. In the root THE DENTIN. 7 1 portions of the teeth the tubules pursue almost a straight course from the pulp to cementum, which in general is perpendicular to the long axis of the tooth. In the apical region they are arranged radially. At or near the external end they branch out and anastomose freely. Inasmuch as it is along the line of the tubules that the infection travels in caries, this arrangement explains how caries may progress along the dentino-enamel juncture and how the enamel is undermined. This also explains the greater sensitivity of the tooth at the dentino- enamel juncture, a clinical fact of common knowledge. The dentinal tubules contain a protoplasmic mass, the dentinal fibrils, which extend from the odontoblastic layer of cells on the ex- X Fig. 97. — Transverse section through root of human molar showing the curvature of the dentinal tubules about the pulp canal. X 4°- (Broomell.) ternal surface of the pulp. These are usually called the fibers of Tomes. Beyond the fact that the fibrils are processes of the odonto- blastic cells, nothing yet is definitely known about the manner of their connection with the nerves of the pulp, nor about the way in which sensory impulses are transmitted by them. Unlike the enamel the dentin is a sensitive tissue and has physiologic connection with the organism. The dentinal fibrils conduct sensory impulses and it is believed that in some way the dentin is nourished through the con- tents of the tubuli. One reason for a belief in the latter is the fact as brought out by Black that the dentin of old teeth has a higher percentage 72 THE HISTOLOGY OF THE HUMAN TEETH. of lime salts than that of young teeth. The growth of the dentin is not completed with the eruption of the tooth, for all of its root is not formed at this period, but continues for some time afterward. The root is completed and the pulp becomes reduced in size, successive layers of dentin encroaching on the pulp-cavity. In the mature tooth the process of dentin formation remains at a standstill until old age, when it will be found that the pulp-cavities are reduced to very small dimensions. The odontoblasts may be stimulated into activity by irritation from the encroachments of carious cavities or by a wearing away of the Cementum. Granular layer. A ^ o wl %^> r * r ^ i»- Dentin. Fig. 98. — Interglobular spaces in the dentin. X 60. (Broomell. Dental Cosmos.) tooth substance from abrasion or erosion. Dentin is deposited on the pulp-cavity wall immediately in relation with the site of the irritation and is an expression of a self-protective activity of the pulp. Dentin thus deposited is known as secondary dentin. It is of poorer structure than normal dentin and not typical in the arrangement of its tubules, which present many interruptions. At the dentino-cemental juncture the dentin presents under the low powers a somewhat granular appearance, and this area is known as the granular layer of Tomes. (Fig. 98.) It consists of the so-called interglobular spaces, which are erroneously so named as in the fresh THE CEMENTUM. 73 specimen they are not spaces but are areas of imperfectly calcified dentin. They are filled with protoplasmic tissue through which the dentinal fibrils may be made out. In the dried specimen they appear as spaces because of the desiccation and contraction of their protoplasmic con- tents. These so-called interglobular spaces are often found else- where scattered through the dentin, usually occupying positions cor- responding to a stage in the development of the dentin. THE CEMENTUM. Histologically considered cementum is very closely related to sub- periosteal bone both in its structure and development. It forms the external covering of the roots of the teeth, serving as a medium of at- tachment between the pericementum and the dentin. At the cervical Fig. 99. — Cementum from cervix of adult tooth. X 4°- (Broomell.) margin, it abuts upon tlxj edge of the enamel or slightly overlaps it and at this point is thinly distributed over the surface of the root. It increases in thickness as the apex of the root is reached and the mature tooth is of considerable thickness in this region. While its structure resembles that of bone in many particulars it differs in having no Haversian system and is easily distinguished from it under the microscope. It presents for examination a matrix of partially calcified organic material containing lacuncB and canalic- 74 THE HISTOLOGY OF THE HUMAN TEETH. uli. The matrix or ground-substance is similar in structure and com- position to that of bone. The lacunse are spaces scattered through the matrix which are occupied in the recent specimen by the cement corpuscles, which are cement-forming cells or cementoblasts which have become encapsulated during the calcification of the tissue. The canaliculi extend from the lacunse and transmit the processes of the cement corpuscles. Beside these elements the tissue contains the cement fibers which are calcified fibers of the pericementum. It is developed by the deposit of successive lamellae upon the dentin surface and these are visible under the microscope as its incremental lines. Fig. ioo. — Cement corpuscles of the outer strata. X 40. (Broomell.) The character of the tissue varies with its position upon the root and with the period of tooth development at which it is formed. The matrix next to the dentin is more nearly homogeneous than elsewhere. Under the microscope it appears somewhat granular and is characterized by the absence of lacunse and canaliculi. (Fig 99.) This is also largely true of the whole thickness of the cementum near the cervical margin as lacunae are infrequent there. The lamellae making the successive additions to the tissue increase both in number and thick- ness as the apex of the tooth is approached, and the lacunae become more abundant in them. The cement corpuscles which occupy the lacunae are masses of protoplasmic tissue which are the remains of cementoblasts. They THE CEMENTUM. 75 are most abundant in the middle layers of the cementum, are absent in the portion next the dentin, and are infrequent in the outermost layers. (Fig. loo.) Their processes are usually directed toward the outer surface of the tooth, and these occupy the canaliculi above re- ferred to. Another element of the cementum which is the most variable of its histological constituents is the cement fibers. (Fig. loi.) These, according to Black, are principal fibers of the pericementum which have been caught in the developing tissue and calcified. In some rare instances they may be observed to extend from the innermost / \ Fig. ioi. — Cemenlal fibers of die middle strata. X 60. (Broomell. Dental Cosmos.) layer uninterruptedly through to the surface, but they are usually of much shorter extent. Sometimes they correspond in length only to the thickness of one lamella and sometimes to that of two or more. This variation is due to the manner of growth of the cementum and to the fact that the attachment of the pericementum is constantly varying, the fibers being frequently cut off and reattached at different positions. Thus the cement fibers which terminate at the surface of a lamella are those whose attachment has been altered at the com- pletion of the lamella. The fibers are of most frequent occurrence in the apical two-thirds of the tissue and in the central strata of this re- 76 THE HISTOLOGY OF THE HUMAN TEETH. gion. Broomell has called attention to the presence of fibers in bun- dles in the oldest lamella, the bundles being arranged radially to the long axis of the tooth. The fibers which extend from the dentin do not have any direct connection with it, but usually terminate here by break- ing up into fibers which run more or less parallel to its outer surface. This is to be expected when the method of cemental development is remembered. In some of the multi-rooted teeth the cementum bridges over the gap from one root to the other, building in the space solidly. Usually some evidence in the way of cement cells or mesoblastic tissue remains to show where the extensions from each root have united. In this type of tissue the lamellae are poorly marked. The formation of cementum goes on more or less constantly during life, as cementoblasts are constantly present in the perice- mentum next to the tooth. In youth the cementum is thin as com- pared to that found in adult life and iii old age. The cementoblasts are sometimes called into activity after the tooth is formed by some pathological excitant, and this condition is known as a hyper-cementosis of the tooth. The tissue thus formed may be of such extent as to complicate the extraction of the tooth, or it may press upon the nerves leading to the pulp or to that of some other tooth and cause obscure pains which are difficult to recognize clinically. The pathologic cementum is usually upon the apical portion of the tooth, and is not typical histologically. Union occasionally occurs between the roots of different teeth by a fusion of the cementum in a manner somewhat similar to that in which the roots of a tooth unite. This gives rise to the so-called fused teeth which are occasionally found. THE PULP. The dental pulp consists of the soft tissues occupying the central cavity of the tooth known as the pulp-cavity. It is the somewhat changed remains of the dental papilla, the formative organ of the den- tin. It is composed of soft embryonal connective tissue, odontoblastic cells, blood vessels, and nerves. No lymphatics exist in the pulp — a fact of pathologic interest. It has two functions, the formation of the dentin, a function practically quiescent in the adult tooth, and the nutrition and innervation of the dentin. The odontoblasts, through the medium of which the dentin is formed , are a layer of cells occupying the entire periphery of the pulp and in close relation with the dentin. (Fig. 102.) They exist as a single layer THE PULP. 77 of cylindrical cells during the formative period of the tooth and until late life, when they become rounded or spheroid. They possess three kinds of processes which are usually referred to as dentinal, lateral, and pulpal. The dentinal processes, of which there is only one to an odon- toblast (occasionally two may be found), are the dentinal fibrils or fibers of Tomes which enter the dentinal tubules; the lateral processes :' '~-■-^'-;"^v'- . n : ■ ■ • ' . ' *,,%; "-^v Fig. 102. — Section of developing L^^wiii ^^i ii^^Liian embryo near seventh month of fetal life. F. Ameloblasts. H. Dentin. I. Odontoblasts. B. and C. Cells of reticulum of enamel organ. D. Stratum intermedium. X i7S- (Williams. Dental Cosmos.) are numerous and by this means the odontoblasts are connected to each other; the pulpal processes extend into the "layer of Weil," a transparent layer of tissue in relation with the pulpal ends of the odontoblasts, and there become lost to view. The odontoblastic cells have large, oval, deep-staining nuclei situated near the pulpal ex- tremity of the cells. This layer of odontoblasts is often called the memhrana eboris. 78 THE HISTOLOGY OF THE HUMAN TEETH. The layer of Weil, situated just below the odontoblasts, is a trans- parent layer of tissue containing very few connective tissue cells, and then below this comes the main body of the pulp tissue. (Fig. 103.) This is composed of connective tissue cells, which may be either stel- late or spindle-shaped, with a large mass of intercellular substance, •'- N :*» kv'xWs .< Fig. 103. — Section of developing tooth of embryo calf. A. Stellate reticulum. B. Stratum intermedium. C. Ameloblasts. D. Dentin. E. Odontoblasts. F. Blood vessels with corpuscles in situ. X 275. (Williams. Dental Cosmos.) together with a few round cells which Noyes says "are probably young cells which have not yet acquired the adult form." The blood vessels of the pulp communicate with the general cir- culation through the apical foramen or foramina of the tooth. One or more small arterial trunks enter the pulp-cavity at the apex and, coursing occlusally through the center of the tissue, give off many branches. Near the occlusal end of the pulp they further divide into capillaries and form a fine plexus around the peripheral portion of the pulp. The blood vessels are generously distributed through the tissue. THE PULP. 79 The veins form a similar plexus and a central vein analogous to the artery receives the blood from these many venules and conducts it through the apical foramen. Especial interest attaches to the thinness of the walls of the pulpal vessels. The arteries are almost entirely without the external fibrous coat and the muscular layer is represented by a single involuntary fiber, while the veins have only a single layer of endothelial cells to form their walls. For this reason the pulp is particularly unable to resist any tendency to hyperemia, and as the tissue is confined in a cavity with unyielding walls, the pulp-cavity, and as the apical exit from it is small and easily blocked, hyperemia of the pulp is attended with a greater amount of pain than in any part of the body, because the nerves are easily stimulated by the pressure of the blood in the pulp- cavity. When inflammation supervenes and inflammatory products are to be removed, the absence of lymphatics further adds to the diffi- culties of the situation. These facts explain the observed clinical experience associated with pathological conditions of the pulp. The nerves of the pulp are transmitted through the apical foramina together with the blood vessels. Several bundles of medullated nerve fibers enter the foramen and break up into a plexus of nerves which are widely distributed through the pulp tissue. Just below the layer of Weil, the fibers may be seen to lose their medullary sheath, when they penetrate this and are lost between the odontoblasts. None have been traced into the dentinal tubules. The sensory nerves of the pulp are only capable of transmitting sensations of pain, which may arise from mechanical, thermal, or chemical stimuli. It is not possible to localize these sensations to any particular tooth, so that one is not able to refer them to the tooth in which they arise. Pain originating in one tooth may be referred to any other in either the upper or lower series. It has been said that the pulp had for its function the nutrition and innervation of the dentin. While dentin is of course a non-vascular tissue, the physical difi"erences in new dentin and that which is found in an old tooth are often so great as to warrant the belief that in some way it may be changed after it has formed. This of course can only be through the medium of the protoplasmic contents of the tubuli, but how this occurs if at all is still only a matter of conjecture. This is also true of the sensory innervation of the dentin. The dentin is sensitive to stimuli of a chemical, mechanical or electrical nature, and the dentinal fibrils are instrumental in delivering these. No nerve fibers have been traced into the tubules, but nerve endings are closely associated with the odontoblasts. It is believed that the 8o THE HISTOLOGY OF THE HUMAN TEETH. dentinal processes of these cells in some way transmit the stimuli. Of course with the removal or death of the pulp, all sensitivity of the dentin ceases. THE PERICEMENTUM. The fibrous membrane intervening between the root of the tooth and the alveolus is known as the pericementum or peridental mem- brane. While not a tissue of the tooth proper, it serves to connect it with the osseous skeleton and performs so many functions associated with the tooth that it deserves especial attention. It is composed chiefly of white fibrous connective tissue, and be- sides containing the blood vessels and nerves necessary for its proper functioning, contains a variety of other cellular elements, the functions of which will be discussed later. The chief oflEice performed by the pericementum is the retention and support of the tooth in its socket, in addition to which it has a developmental and nutritive relation to the cementum and the alveolus, and serves as the touch-organ of the tooth. Inasmuch as the fibrous elements of the membrane are in predomi- nance and as they are related to its chief function, they will be described first. The fibrous tissue of the pericementum is of two kinds — first, the principal fibers, so called by Black because they were greatest in num- ber and most important in function, which extend from the cementum to the alveolar wall or into the gum tissue and are attached to each; and second, the interfibrous tissue, which is the fibrous tissue com- posed of spindle-shaped and stellate cells which intervenes between the principal fibers themselves and between these and the other perice- mental elements. These fibers pass from the tooth to the alveolar wall in all portions of the socket, their ends are firmly built into the cementum at one end, in which they are spoken of as Sharpey's fibers, and into the bone of the alveolar process at the other, and they me- chanically support the tooth in its socket. Their arrangement is somewhat different in different parts of the membrane and so it will be necessary to give their direction in its various portions. In the gingival portion of the membrane, where they are thickest, they extend from the cementum in three directions. (Fig. 104.) One set passes occlusally into the gingivus to support this and make it hug the neck of the tooth, and another passes over the alveolar border to blend with the fibers of the muco-periosteum of the alveolar process. These two sets of fibers are in greatest abundance on the lingual side of the teeth, serving to protect this against violence from food in mastication. THE PERICEMENTUM. 8i The third set of fibers passes almost horizontally outward and they are either attached to the alveolus, or on the proximal sides in young sub- jects they pass over to the adjoining tooth and become continuous with its pericemental fibers. Of this third set of fibers, some pass radially directly to the alveolar bone, and on the lingual side these are most numerous, while others after leaving the cemental surface pass tangentially in bundles, and are attached to the process at points mesial or distal to where a radial direction would have taken them. Fibers Fig. 104. — Section showing pericemental fibers attached to the cementum. (Broomell.") These fibers serve to prevent the rotation of the tooth about its long axis, while the radial fibers resist force tending to move it laterally. In the membrane intervening between the gingivus and the apex of the root, the principal fibers pursue either a straight horizontal course from cementum to bone or they are directed occlusally. The effect of this arrangement is to swing the tooth in its socket, as it were, and it enables the tooth to resist the force of mastication or any other which tends to depress it in its socket. (Fig. 105.) 6 82 THE HISTOLOGY OF THE HUMAN TEETH. In the apical region the principal fibers extend radially from the root, spreading out from it in all directions to the alveolar socket. The interfibrous tissue fills in the spaces between the principal fibers which is not occupied by the blood vessels and nerves and the special cellular elements presently to be described. This arrangement of the fibers of the pericementum is remarkably adapted to hold the tooth in its socket, to enable it to resist stress placed Fig. 105. — Section through alveolus and root of lateral incisor near the gingivus showing direction of fibers of pericementum. A. Pulp with blood vessels and nerves. B. Dentin. C. Cementum. D. Alveolar process. E. Interfibrous portion of perice- mentum. (Noyes. Angle's Orthodontia.) upon it, and yet to yield slightly to the stress and thus to break the force of the latter. While the fibrous tissue is of the inelastic variety, the fibers are not on tension all the time, and thus permit a certain elasticity to the tooth. This elasticity is contributed to in the young membrane by the blood vessels, which are very numerous, a condition which has a cushioning effect upon the tooth. This elasticity permits the slight movement of teeth when separating them for operative pro- cedures and in the beginning of their orthodontic treatment. THE PERICEMENTUM. 83 The cellular elements are fibroblasts, cementoblasts, osteoblasts^ osteoclasts, and certain epithelial structures. The fibroblasts are long, spindle-shaped cells found in greater num- bers in the young membrane and almost absent in that of old age, and are for the repair of the fibrous tissue. They may be observed in the bundles of principal fibers. The cementoblasts which are concerned with the formation of the cementum, are flat, scale-like cells found on the surface of the ce- mentum occupying spaces between the principal fibers. They are irregular in outline and the bay-like depressions in their periphery are occupied by fibers. They have oval nuclei and are difficult to find in longitudinal sections. The osteoblasts are situated upon the alveolar wall which they assist in forming. They are spherical cells with round nuclei like osteo- blasts elsewhere found in periosteum. They build the bone around the fibers of the pericementum, thus strongly attaching it to the bone, and the calcified fibers are here also known as Sharpey's fibers. The osteoclasts are not constantly present in the pericementum, but are found when absorption of the calcified tissues is in progress. They are often spoken of as "giant cells" because of their size and the great number of their nuclei of which as many as twenty-five are some- times found. They are capable of acting upon bone, cementum or dentin. Although the exact manner in which they remove the calci- fied tissue is not known, it is necessary for them to be in contact with it and they are found in the bay-like excavations which they have pro duced. These excavations are known as "Howship's lacunae." The epithelial structures of the pericementum were first described by Black, who referred to them as the glands of this tissue. While their glandular character has not been demonstrated, they resemble the glandular tissue in that they are chains of cells epithelial in all their characteristics which are distributed throughout the membrane. Occasionally they appear arranged as a tubule having an impercepti- ble lumen, but no connection with the oral epithelium has been traced. They are doubtless remains of epithelial tissue carried down from the oral epithelial at the time of the formation of the enamel organ. They are fairly uniformly distributed through the membrane accord- ing to a diagrammatic plan by Dr. Black. The blood vessels of the pericementum are numerous and are de- rived from three sources. Two or three branches are given off by the artery of the pulp before it enters the apical foramen. These anas- tomose with branches of arteries from the alveolar process and with 84 THE HISTOLOGY OF THE HUMAN TEETH. Others from the mucous membrane at the gingival margin, forming a plexus of arteries which bountifully supplies the membrane. These are more numerous in the young specimen and occupy approximately the center of the tissue, but decrease in number and size as life ad- vances and in old age are found in channels upon the alveolar wall. The nerves are derived in a similar manner from those entering the pulp, from the bone itself and from the mucous membrane at the gin- givus. They unite and give the tissue an abundant nerve supply. The medullated fibers terminate without special nerve endings. They transmit sensations of pain and ordinary sensation and thus the peri- cementum is the touch-organ of the tooth. CHAPTER III. HYGIENE AND ARRANGEMENT OF LIGHT IN THE OPERATING ROOM. BY C. N. JOHNSON, M. A., L. D. S., D. D. S. The hygiene and control of light in an operating room is a very important matter, affecting as it does the health and comfort of the practitioner. In an office where the dentist is confined chiefly to operating, as is the case in so many today, it is essential that some attention be given to the room where the working hours are mainly spent. It is undoubtedly true that many dentists have seriously impaired their health and shortened their years of usefulness by con- fining themselves in an abnormal environment, and the subject is worthy the careful study of every operator. The first essential in an operating room is good ventilation and sunlight. The operator should not stand in a draft but he should have plenty of fresh air and not breathe the vitiated atmosphere so fre- quently found in dental offices. The admission of sunlight is very important if it can be arranged without taxing the operator's eyes,, though this is not always possible with the location of many of our offices. Sunshine is a great purifier and is worthy of more considera- tion in this respect than it usually receives. There is a difference of opinion among practitioners as to which is the preferable light for operating, very many urging the advantage of a north light, but this has the limitation of not admitting the sun. It would seem that the best arrangement was to have a corner room for operating with two windows in it one for the operating chair and the other to admit sunlight. A north-west room lets in the sun only in the afternoon and in the summer is very hot, and the same may be said of a south-west exposure. A north-east room is better, having the chair face the north window with the east window at the operator's back. But this room admits very little sunshine in the winter months when it is most needed. What is probably the best arrange- ment is to have a south-east exposure with the chair facing the east. The sun is usually so high by the time operating begins that it does not interfere with the work, and in summer it is so far north that it 85 86 HYGIENE AND ARRANGEMENT OF LIGHT does not shine in the south window sufficiently to cause undue heat. During the winter months it pours into this window, flooding the operating room, coming in at the operator's back, and therefore not injuring his eyes by causing too bright a light to shine in front of him. This is a very important consideration which many practitioners overlook — the avoidance of too much light for the operator to face. There is a constant tension on the eyes when the individual is looking toward a light, and this is equally true of a reflected light which enters from the rear and is thrown back in the face by a bright wall in front. This makes it very essential that the color of the walls in an operating room should be such as to absorb light and not reflect it. Bright colors are to be avoided in decorating, and this one room of all others should be given over to service rather than to attempt to make it attractive by the use of light shades. Fortunately it may be made comfortable to the eyes without sacrificing artistic beauty if the proper colors are selected. Where paper is used on the walls it should be a solid color without pattern. Green is a suitable shade as also is the deep brown known as chocolate. The latter produces a soft, restful effect in a room, unobtrusive in any way, and unobjectionable from an artistic sense. The size and location of the window in front of the operating chair are important factors in securing effective light without eye strain. The window should be sufficiently high to carry the light directly down from the sky into the patient's mouth when the head is tipped slightly back, and there should be nothing to interfere with the direct passage of the rays such as trees in front of the window or tall buildings standing too near. A very common error made by practitioners is the admission of too much light in the operating room. The idea seems to prevail that the more light the better, but this is a serious mistake. It is true that a very excellent quality of light is required, and in the immediate vicinity of the patient's mouth the light cannot be too strong short of sunshine. But this is the only vicinity where it is needed, and the diffusion of light over a wide area by having a very large window in front of the chair is a severe tax on the eyes which few operators realize. If a window is too large some of the light should be shut off with a shade, and this is particularly true where the window runs down so near the floor as to flood the lower part of the room with light. The operator is looking downward much of the time and this flood of light is reflected in his eyes. In any arrange- ment of an office whereby an operator must use one window for oper- ating and face another as he stands at his chair he should cut off every IN THE OPERATING ROOM. 87 ray of light from the window he faces by a dark shade, and in the same connection he should avoid anything on the wall in front of him which will reflect the light in his face. A bay window while very alluring to some practitioners is extremely bad unless the window looking toward the operator's face is heavily shaded. The only direction from which it is permissible to admit light to the room except that which comes straight to the patient's face is at the operator's back, and as has just been intimated there should be nothing in front of him which would reflect this light back in his eyes. Many operators go on year after year suffering eye strain and unconscious of the cause of their discomfort through ignorance of the essentials necessary in the arrangement and control of light in the operating room, or through carelessness in carrying them out. When it is considered how important the eyesight of the dentist is it would seem only a reasonable supposition that every operator should give some attention to a matter so vital to his future comfort and usefulness The essentials are simple and are capable of being carried out in a reasonable degree at least by every practitioner. CHAPTER IV. . ASEPSIS IN THE OPERATING ROOM. BY A. E. WEBSTER, M.D., L.D.S., D. D. S. Under this heading must be considered the possibilities of patients carrying contagious diseases to the dental office, and other patients becoming infected from the germs of disease left in the plush dental chair, the carpets, curtains, and hangings about an operating room. There is also the more frequent and possible means of transmitting disease to be considered, the actual contact from instrumentation. It may not often occur in an ordinary practice that patients suffer- ing from a contagious disease apply for dental treatment, but it does often happen that patients apply while members of their family are suffering from a contagious disease. Such diseases as measles, diphtheria, whooping cough, scarlet fever, chicken pox and small pox are said to be capable of transmission by clothing. Then there are such diseases as tuberculosis, pneumonia, influenza and some pus infections which may be transmitted by an unkept office equipment. Disease may be transmitted through the water supply, the air supply or noxious gases. Even darkness is conducive to the growth of micro- organisms. To minimize as far as possible the transmission of contagious diseases in a dental office the operating room should have an abundance of direct sunlight, there should be no draperies or hangings about the room. The walls should be of hard finish and capable of being cleaned. The woodwork of plain finish, no crevices for the collection of dust. Cabinets, brackets and shelves should be plain and of hard finish. Drawers should not be lined with baize or fabric of any kind. The chair, and especially the head rest, should be covered with some material which is capable of being cleaned without destroying it. Plush is decidedly objectionable. The floors should be capable of being cleaned, as is the case with hard wood finish or linoleum put down in a whole piece and cemented at the edges so that water may not get under it. If a rug or cork is used to stand upon at the chair it can be cleaned frequently. Carpet in an operating room is the most unhygienic of all floor dressings. 89 90 ASEPSIS IN THE OPERATING ROOM. Typhoid fever and other intestinal infections are most frequently transmitted by the water supply. In some cities and towns the water is never fit to drink while in others it may be drunk if boiled and in others the water may be unfit for use only at certain periods. Water which is unfit to drink is unfit to wash a drinking glass or to rinse the mouth. The air supplied to an operating room is of some importance, especially to the operator, because he so constantly breathes it. Hot air heating often supplies air which is obtained from a dirty, damp basement or from sewer ventilators. Sewer gas often enters an oper- ating room from poorly trapped or ventilated plumbing. The fountain cuspidor is rarely trapped and is often the source of sewer gas. Coal gas leaking from defective pipes is an insidious kind of poisoning that an operator may not notice for months. The proper ventilation of an operating room deserves some consideration. The keeping of an operating room aseptic is no small under- taking. In fact it is well nigh impossible and yet it may be kept clean enough so as not to be the means of spreading contagious diseases. Dust is the enemy of cleanliness and health. Every crevice, every crack, every shelf and every loose fabric is an element of danger. The walls, shelves, brackets, cabinet, chair, woodwork, light fixtures, windows, in fact everything should be thoroughly cleaned once a week, with a brush, soap and water. After this the room may be closed up and formaldehyde gas set free in sufficient quantity to fill it and allowed to remain for some hours. Formaldehyde tablets may be evaporated by heat over a Bunsen burner. Three or four tablets may be placed on a piece of flat metal over the gas flame. The heat necessary to evaporate the tablets is not very great. An equally efficient method is to place a couple of ounces of formalin in a dish over the Bunsen flame which will quickly drive off the formaldehyde gas. Once the gas begins to come off no one should remain in the room because the gas is very irritating to the air passages. The floors, chair, cabinet, bracket and all handles should be carefully cleaned and dusted with a damp cloth every day, and if there is any reason for suspecting that a patient has been in the office who was suffering from a contagious disease there should be general disinfection and ventilation. Such parts of the furniture and equipment as the operator is likely to handle in his ordinary duties should be wiped off with a cloth made damp by a five per cent solution of phenol or bichloride of mercury one to the thousand. There should be no waste cotton or dressings ASEPSIS IN THE OPERATING ROOM. 9I permitted to fall upon the floor. There should be a convenient re- ceptacle for such things, that can be emptied frequently and sterilized. There is nothing much more unclean than the ordinary waste cotton holder where the plier points are drawn over the edges to remove the cotton, unless the holder is sterilized after each operation. Soiled towels, napkins and rubber dam should be immediately removed from the operating room. The dental cabinet should be thoroughly cleaned and wiped out with a damp cloth once a week and disinfected by the evaporation in it of formaldehyde gas. Each tray and shelf containing operating instruments should be cleaned daily. Besides this the tray containing operating instruments should be covered with some material which can be easily removed and sterilized or destroyed. No instruments should be permitted in the cabinet until they are first sterilized. A fairly thick paper is quite suitable to cover the operating tray and may be removed after each patient and a new one placed in position. What are known as hygienic trays which are made of glass or granite are suitable and readily cleaned. The table on the bracket arm is often made of such materials and of such a form that it cannot be kept clean. A simple plain table of glass without any elaborate frame to hold it is all that is necessary. Once any decoration is attempted there are crevices for dust. With the swinging trays from the cabinet it is not necessary that the table should contain places for the operating instruments, medicine bottles, gold, amalgam and cement. The demand for a dental equipment which can be kept aseptic has given the profession cabinets, tables and chairs of white enameled iron. This kind of equipment is easily kept clean because of the hard finish and the few crevices for dust. The bracket table may be covered with a thick paper which can be removed after each operation and destroyed. The operator should be suitably dressed for the work he has to perform. His coat should be of washable material, close fitting around the neck and sleeves, no buttons or flaps to catch in his patient's hair or clothing. Long hair and whiskers are not conducive to aseptic operations. The operator should aim to prevent his expired air from entering the patient's mouth or nostrils. The operator's handsare almost impossible of disinfection ; because though the surface may be sterile for a while it soon becomes infected from the natural exudations from the deeper parts of the skin. These exudations may be hindered for a time from pouring out by the applica- 92 ASEPSIS IN THE OPERATING ROOM. tion of astringents but the more the hands are used the more active the glands become. Those hands which are covered with a smooth, unabraded skin and have regular well kept finger nails can be made more aseptic than the dry, scaly hands with rough, irregular nails. Rough and violent scrubbjng and scraping of the hands is likely to put them in such a condition that even this will not clean them. The nails are difficult to keep in condition unless trimmed short and kept smooth by files and brushes. Sharp instruments should not be passed under the nails to clean them because they scratch the tissue, leaving opportunity for lodgment of bacteria. Orange wood properly trimmed will serve to clean under the nails without wounding. The dentist should look upon his hands as one of his assets and should avoid everything that might in any way disfigure them or roughen the skin. The hands should be carefully washed in warm water and soap, the nails scrubbed thoroughly and cleaned beneath and again washed in running boiled water. This will suffice for ordinary cases, but if the hands have been exposed lo pus infections or the saliva of the patient, or an operation is to be performed which demands the breaking of the mucous membrane or entering the circulation of the patient greater care must be exercised in cleaning the hands. They should be washed as above and then immersed in a one in forty phenol solution for three to five minutes or a two per cent solution of per- manganate of potash, or one in a thousand bichloride of mercury. Following this, alcohol may be poured over them. But if absolute certain asepsis is demanded rubber gloves should be worn. The general surgeon of today will not depend upon the disinfection of his hands, but wears gloves. There is no doubt that the dentist's greatest precaution should be to prevent the transmission of infection from one patient to another. While the patient may become infected from his own saliva the dangers are not so great as from infection from without. As the dentist operates for a patient his hands are certain to become infected from contact with the patient's lips, face, mouth or clothing, and should be cleaned and disinfected as parts of the operation are reached which demand aseptic conditions. The operator should avoid touching his clothing, his face, hair, or the furniture while treating roots of teeth or doing operations which may bring his instruments in contact with abraded surfaces. Before cotton is wound on a broach for treating root canals the fingers should be immersed in a bichlorid solution or a formaldehyde solution. The field of operation should be as carefully prepared for operation as the hands or instruments. Patients often visit the dentist whose ASEPSIS IN THE OPERATING ROOM. 93 mouths are not even freed from particles of food from the last meal or two. It is well to have such patients rinse their mouths as thoroughly as they can with a two per cent solution of permanganate of potash before even a thorough examination is undertaken. A blast of air from a compressed air tank or a spray of one of the essential oils will clear an area for inspection. Not having these appliances a stream of tepid water forced between the teeth will clear out an interproximal space. Large cavities containing decomposed food and decalcified dentin should be opened and washed out with abundance of water. If the cavity is to be filled at once or the pulp involved the teeth in its vicinity should be dried and wiped with alcohol. And if the rubber be in position all of the exposed teeth should be thoroughly sopped with a strong disinfectant. Root canals should never be opened without thoroughly cleansing the cavity itself and the teeth about. The sterilization of instruments is perhaps more important than the sterilization of the hands or the field of operation because they more frequently come into contact with the secretions of the body. This is especially true of extracting forceps, lancets, clamps, separators, matrices, files, trimmers, scalers, broaches, explorers and hypodermic needles. Instruments should be selected with a view to their easy sterilization. Cone socket instruments and deeply knurled or wooden handles are not so easily sterilized as all steel and fairly smooth instru- ments. The dental hand-piece is difficult to sterilize without danger of rust or corrosion. A thin sheet metal covering is now made for the hand piece which completely covers it and may be removed and sterilized between patients. There are two general methods of sterilization in common use, (i) by heat and, (2) by drugs. As a rule heat is more certain but even boiling for ten or fifteen minutes will not destroy the spores of some organisms. Sterilizers are most satisfactory which will permit of the water being drained off allowing the instrum. uts to dry from their own heat. Sterilization by drugs is not always satisfactory because efficient drugs have to be used in such strength that unless the instruments are wiped dry before using there is a possibility of injuring the patient's mucous membranes. The odor and the time required for some drugs to act are serious objections. A 3 to 5 per cent solution of formalde- hyde will sterilize instruments in a shorter time than any other drug or combination of drugs which are at all suitable for the purpose. Formaldehyde solutions will rust instruments rapidly but if borax 94 ASEPSIS IN THE OPERATING ROOM. be added rust does not occur. No dependence should be put in proprietary disinfectants for either the mouth or instruments. Suffi- cient tests of the efficiency of these nostrums have been made to prove their uselessness. All the instruments used in an operation should be removed from the bracket table and washed in water and sterilized and then placed in their respective places in the cabinet. Such instruments as burs and serrated surfaces should be cleaned with a brush before being sterilized. The revolving brush wheel on the engine for cleaning burs is objectionable and should go with the cotton holder unless cleaned after each time it is used. After broaches are sterilized they should be kept in a closed drawer which is frequently sterilized with formaldehyde vapor or in alcohol. The hypodermic needle may be pressed into a cork which tightly fits the bottom of a glass barrel about an inch in diameter and three or four inches in depth. The cork may be saturated with any steril- izing fluid which will not rust the needle. Such a needle is always ready for use. If the barrel be deep enough the whole syringe may be kept within it and covered with another cork. The nozzle of the water syringe should be kept in the formaldehyde solution when not in use. The nozzles of the spray bottles should be similarly sterilized. The sterilization of materials used by the dentist deserves some attention. Gold, amalgam, cement, and gutta-percha for fillings need little attention except where they are brought into contact with vital tissues. Gutta-percha is frequently brought into such contact but it is sterilized by heating before being used. The phosphoric acid and chloride of zinc prevent the carrying of infection by the ordinary cements. Gutta-percha points used to fill root canals are often inserted directly from an unclean drawer or box. They should be kept in alcohol in a wide mouth bottle well stopped. Cotton used for wipes should be sterilized by heat and kept covered as much of the time as possible. There are many minor operations performed by the dentist which are cared for in rather a slipshod method. Roots of teeth are ex- tracted about which purulent infections existed and no attempt made to wash out the cavity with any regard for asepsis. The water used and its containing vessel should be boiled, the syringe and the packing should be sterile. Every office should be equipped with sealed glass jars containing strips of boracic and plain gauze of different widths wound on a spool. Cotton wipes may be kept in a similar jar. The jar and its contents may be sterilized in an oven or boiling water. ASEPSIS IN THE OPERATING ROOM. 95 The ordinary fruit sealer is an excellent jar for this purpose. With such an equipment the dental surgeon is always prepared for the management of the many surgical operations he is called upon to perform. CHAPTER V. HYGIENE OF THE MOUTH. BY GEORGE H. WRIGHT, D. M. D. ORAL HYGIENE OF THE INFANT. The highest physical development of the child is largely dependent upon its environment and its food. These two factors may be in- fluenced by the parent and oral hygienist. In order to have a clear understanding of the conditions necessary for a sound oral hygiene we must recognize what physiological proc- esses are concerned in the development of the oral cavity, the eruption of the teeth, and the possible changes which may follow any interference with its normal process and which may result in a distinct pathological manifestation. Heretofore, in dealing with the problem of oral hygiene, we have considered simply the adult, now we propose to take a view of the child when we may first observe the manifestations of the process and activity of the eruption of the teeth. An important factor to be recognized is the pulsating mass of pulp within the tooth, which acts as a minute force constantly applied that impels and moves the tooth onward and out of its crypt through the gum tissue. Any interference in this process induced by unnatural external means may so modify the direction of the eruption of these teeth as to cause not only reflex disturbances of digestion, with many other manifestations of pathological diseases, but may also modify the superstructure of the superior maxilla and cause decided malformations in all the facial bones, including the floor of the nasal fossa, the nasal septum, and the antra, and may also in- duce abnormal growths, thickenings of mucous membrane, enlarged adenoids and other obstructions that disturb normal functioning. Frequently, the physician called in to attend a child who is dis- turbed in the process of teething, so called, will indiscriminately lance the gum, a fibrous tissue immediately over the erupting crown, and in that manner seek to give the child relief. He may succeed tempora- rily, because the arterial tension below the erupting tooth is relieved. The cusps of the tooth emerge through the wound and there is liber- ated into the oral cavity a mass of liquefied, alveolar bone and degen- erate connective tissue which normally is absorbed by the lymphatics. 97 7 pS HYGIENE OF THE MOUTH. Only the crown of the tooth is formed at this time and is loosely held within its alveolar crypt. The lancing relieves the tension which later subsides, and often the tooth returns to its former position below the gum; the cicatrix heals rapidly and histologically will exhibit a denser fibrous mass, considerably matted, and very resistant, and very difficult for the erupting tooth to cut through, in which event the lancing may give temporary relief, yet in reality be the means of causing a retarded normal eruption. At birth, the crowns of all the temporary teeth are formed, and any change in environment of a tooth may have an important influence upon the future lines of growth of the jaws and adjacent structures, for, coincident with the eruption, we have the development of the inferior meatus of the nose; at birth it is relatively unformed. The maxillary sinuses, sphenoidal and frontal, are post-natal developments. At birth the developing crowns of the permanent teeth occupy the position of the maxillary sinuses. The immediate result of this retarded eruption may be observed in a decided deflection of the lines of growth, not only of the alveolar periosteum, but also of the adjacent bones. In the region of the intermaxillary bones, where the central incisors have been held for an abnormal length of time, the rest of the structure immediately above will suffer a corresponding retarded elongation. This may be observed in a later bending, or buckling, of the nasal septum, thereby closing on one side the nasal fossa, and on the other exhibiting a very wide opening so that the intranasal space is too wide on one side which admits a too great inrush of air, and on the other a congestion that admits of none with its attendant complications. These deformities have their origin during the period of and par- ticularly after the eruption of the first teeth; later the arch of the teeth, or substructure of the superior maxilla, loses some of its units of strength in supporting this structure, because the points of contact of the tem- porary teeth are unequal. Undue pressure is brought to bear at iso- lated points in closing the mouth, with the reflex result that there will be distortion in the structure above. The permanent teeth which are developing immediately following the temporary teeth, continue this tendency to deformity, and the process may go on up to twelve years of age and then may become progressively worse. In the meantime some enthusiast for early extraction may further complicate this deformity by the removal of some of these teeth mal-placed, and at this point we find one of our greatest complications as it leads to an abnormal, unhygienic condition of the mouth. Triangular spaces are formed , into which are lodged accumulations of detritus difficult to remove, and, in ORAL HYGIENE OF THE INFANT. 99 consequence, there follows in its train most of the destruction of the teeth through caries, impaired digestion and imperfect respiration. We know that the crown of enamel with its interlining of dentin is formed first, and subsequently the dentin thickens and elongates; then it becomes covered with cementum, and ultimately the root or fang is developed with its covering of peridental membrane. But this completed growth is not a necessity for the eruption of the tooth, because we find upon dissection of the jaws, from six months up to six years, that the teeth erupt frequently without a vestige of a root, and, consequently, the disturbances within the oral cavity, and reflected in impaired digestion of the child — to be described in detail later — are not "due to the elongation of the root and consequent pressure upon the developing jaw," but to some other cause. This is fundamentally a problem for the specialist in oral hygiene, inasmuch as the mother of the child will frequently inquire of her den- tist, how soon she must "begin the care of baby's mouth." Fre- quently a child from four to six years will, either through an accident lose the central temporary incisors, or loosen them by the habit of prying a pencil between the teeth; soon they are removed by the child, parent or dentist. At this period in the development of the per- manent central incisors (immediately following the temporary incisors) we find only the broad crown of enamel and no roots, and the crown situated high in the intermaxillary proce^. The too early loss of these temporary teeth, from whatever cause, may induce a thickening in the floor of the nasal fossa and malformation of adjacent structures, because the permanent central incisors are held by a new deposition of alveolar bone and a denser fibrous mass of gum tissue. Concurrent with the continued deposition of dentine and cementum at the apex of the tooth, the erupting force is reduced, because the apical region becomes more constricted, thereby reducing what is normally a wide area of vascular pulsating tissue which was the impelling force nec- essary for the eruption. These malformations become important factors in producing the subsequent pathological conditions within the mouth. The erupting tooth of a child slowly develops to the surface after absorption of the alveolar periosteal crypt immediately above, and ul- timately cuts its way through a fibrous mass of gum tissue. It is hastily assumed that all possible disturbance with that particular tooth has ended, but a few hours later, or the next day, the tooth may dis- appear below the gum into its crypt, leaving a small orifice capable of lodging decomposing food and myriads of bacteria. The fluctuating of the teeth in their coming and going shortly after lOO HYGIENE OF THE MOUTH. their first appearance, is undoubtedly due to the change in arterial tension which is manifested through the large vascular pulp of each tooth. It is possible to record the pulsations of the heart, and count its beat through the freshly erupted tooth. The writer has made ob- servations during the past few years and watched this phenomenon. Under normal conditions, the process of eruption is a natural and orderly physiological procedure on the part of nature. It is not our intention, nor within our province at this time, to go into details con- cerning the periods at which the groups of teeth erupt; that has been dealt with in another chapter. We shall consider, however, those as- pects which either directly or indirectly induce disturbances within the oral cavity, and which we are called upon to treat in order to establish a sound hygiene in the mouth. The mother invariably consults with her dentist upon the first occasion, after giving birth to her child. There have been excessive changes of metabolism, which have occurred during the period of gestation, and this is reflected quite markedly in the secretions, and particularly in the saliva and oral secretions, which become more acid, and in consequence exerts a deleterious influence on the teeth and ad- joining tissues. If the patient has been carefully instructed during the period of gestation as to the proper hygiene for the mouth, the evil effects upon the teeth, as a result of the changed metabolism, need not be fraught with so many evil results, as when entirely neglected and the debris naturally formed within the mouth is allowed to accumulate. ^ Immediately preceding or at the time of the eruption of the teeth, there may be pathological complications within adjacent structures, as in the eye, ear, nose and throat. With this enormous structural upbuilding where nature is elaborating the materials for forty-eight teeth, and the jaws, there is much waste tissue to be disposed of. In close proximity to the erupting second lower molar there is a thick plate of alveolar bone. This bone and fibrous gum tissue in contact must be liquefied and absorbed before the tooth comes through. Some- times there will be a swelling in the region of the submaxillary gland and lymphoid enlargements; intense pain, excessive salivation, fol- lowed by a hot and feverish condition of the oral mucous membrane, extending to the nasopharyngeal region. The disturbance may con- tinue until we find an acute otitis media, with a sinus and profuse suppurative discharge through the external ear, which undoubtedly had its inception in the engorgement of tissue in the nasopharynx or enlarged adenoids encroaching upon the opening to the Eustachian canals and thereby preventing normal drainage. Usually within a ORAL HYGIENE OF THE INFANT. lOI few hours or two days at least, the offending molar will make its appearance through the gum, and disturbance will cease. So, too, in the region of the upper first and second temporary molars, we may find lymphatic enlargements involving the parotid and lachrymal gland and tonsil, with sinus and discharge through the lachrymal duct. The faucial tonsil and normal adenoid upon the side nearest to the erupting tooth may become considerably enlarged through the influence of the lymphatically absorbed waste tissue. Nature has undoubtedly developed and placed these lymphoid organs for a useful purpose during this structural upbuilding. Wanton destruction or removal without adequate cause is to be deplored. If our observations regarding the arterial tension preceding and after the eruption of the tooth are correct, it is safe to assume that blood pressure has been a potent factor in the primary process of eruption, long before it has reached the surface through absorption of the walls of its bony crypt. If, during this early process before the appearance of the tooth, or the congestion of the fibrous gum, there should be from any cause whatever an undue arterial tension, then some of the dis- turbances noted in the young child may be accounted for, although there may be no external evidence of the teeth. There may be a feverish restlessness, periods of excessive salivation, desire of the child to bite its fingers, and rub its eyes and nose. There may be bright red areas in the region of the parotid and sublingual glands externally; possible rise in temperature, with fretfulness and nervous irritability, and reflex disturbances of digestion, with frequent ejec- tions of its food. The mucous membrane of the mouth, under these circumstances, may exhibit a hot and dry surface that lasts for a few hours to be followed by salivation. The etiology of these disturbances in the majority of cases may be referred to improper feeding, as imperfect formulae for artificial foods, too much food, uncleanliness, or indiscriminate feeding, also where artificial foods are swallowed too rapidly and in abnormal quantities. Here, too, we may observe the beginning of maxillary deformities, because the child does not exercise its muscles and jaws as when sucking at the breast, consequently, through lack of function, the palatal arch is not adequately expanded. The child taking its nourishment at the breast obeys a natural instinct, and the mother's milk during the first months of feeding in- creases in quantity with the larger demands of the child, and analysis shows a decline in the nutritive proteids toward the end of the period of lactation. The child thrives best at the breast when the conditions I02 HYGIENE OF THE MOUTH. are normal. When otherwise, then artificial feeding by formula is resorted to, but instead of a decrease in the quantity and proteid con- stituents of the food as observed in nature's method, we find the exact reverse, and the child suffers often in consequence of haphazard, arti- ficial feeding, where the food values are progressively increased, while the naturally fed child is getting but a simple diet and that sparingly. It is not a question as to how much food the child shall take, but how little it should take, in order to preserve the balance of perfect assimila- tion and growth. The salivary glands of the child are functionally active from four to six months, and it is claimed that even in the youngest infant the chemical constituents of the saliva are capable of rendering soluble starchy foods. Some children have been known to digest and assimi- late starch during the earliest months, yet, upon general principles, it is considered very unwise to introduce starchy foods of any kind, because of the mechanical irritation and frequent inability to digest and as- similate them. The one great remedy for reflex disturbances of digestion, as a result of undue tension within the highly vascular tooth pulp, will be found in reduced and careful feeding, and the establishment of normal hygienic conditions. It may be necessary to starve the child for twenty-four hours before beginning with a simple and reduced diet, in order to build up again. In describing the pathological aspect of the oral tissues in the child, the writer in the following has drawn largely from the admirable description found in Barrett's Pathology, Holt's Infancy and Child- hood, and Forchheimer. Stomatitis, in relation to disturbances or inflammation of the mucous membrane of the mouth and adjacent tissues, is in this sense restricted in its application, although the term is a broad one and could be applied to many diverse conditions. Stomatitis is common in infants, and is usually the handmaid of bad hygiene or unsanitary surroundings. This inflammation of the mucous membrane is frequently found where the child is artificially -fed, instead of nursing at the breast. Either the proportion or formula for food is wrong, or there is not sufficient cleanliness and care in scalding the bottles and nipples, which will inhibit the growth of fermentative bacteria. The quality of the rubber in the nipple undergoes change, and under the influence of light and heat decomposes and becomes an active source of irritation to the tissues, which become poisoned. And even though these con- ditions do not exist as to improper feeding or unclean bottles, it is ORAL HYGIENE OF THE INFANT. IO3 possible to develop a stomatitis on account of the accumulation of debris from remnants of food lodged within the orifices of erupting teeth, broken down epithelial cells, and combined products of inflamma- tion, which should be daily removed irrespective of the age of the child. Sometimes the most careful and conscientious nurse or mother will neglect this duty. A simple follicular stomatitis is an inflammation of the mouths of the mucous follicles. Small areas of the surface may be involved, and possibly induce degenerative changes as deep as the mucosa. The membrane will be flecked over with red points. As the inflammation spreads, more follicles become involved until the red points and patches merge, and the entire surface becomes turgid and tumid. As we look into the mouth, the tissues are hot, and dry, and red. There is con- siderable sensitiveness, and the child will shrink when examination is attempted. In the early stages, there will be excessive flowing of watery saliva due to the congestion of the blood vessels surrounding the glands, some febrile disturbance, irregularity of the bowels, and either constipation or diarrhea predominating. Close examination reveals swelling of the muciparous follicles and possibly tiny cysts, due to the accumulation of secretions within them. (Forchheimer.) The adjacent lymphatic glands become slightly enlarged and sensitive. Fortunately the constitutional symptoms with this form of stomatitis are not severe; there may be deranged digestion, vomiting, and a mild attack of diarrhea. The disease runs a brief course, and disturbances are usually easily corrected by care in feeding and cleanliness. In later stages, the degeneration spreads, the mouth becomes dry and parched, the blood vessels are congested and active nutrition is interrupted; then comes stasis or stoppage of circulation, and sloughing of the tissue commences. A child that is fed with a food that it cannot properly digest and as- similate will be poorly nourished, and as a result, almost any form of disturbance may ensue. The irritated condition of the digestive tract may produce diarrhea and gastric disturbances, and may result in ulcerative stomatitis. We have then an advanced stage of the first condition. The functions of the mucous follicles quite cease, and cracks and fissures open in the unlubricated tissue. All the preceding symptoms are aggravated. The child cannot take its food without difficulty, and what is ingested affords little nourishment because of the gastric disturbances that are always present. Aphthous stomatitis, or herpetic stomatitis as Holt calls it, is a form that may attack people of almost any age, and is characterized I04 HYGIENE OF THE MOUTH. by some special appearances. Small round or oval ulcers appear upon the reddened mucous membrane of the lips, cheeks, tongue, or gums. They are from one to three lines in diameter, very little de- pressed, v^ith a yellowish or white floor, and a red, narrow, perhaps slightly indurated, border. Sometimes two or more of them become confluent, thus forming an irregular, large ulcer. When these heal they leave no cicatrix. The aphthae do not spread like the spots in ulcera- tive stomatitis, and they are distinctly painful, while the ulcers are not. Usually there is an increased flow of saliva accompanying them, the mouth is hot and feverish and the tongue heavily coated. Some- times the saliva excoriates the skin and the lips are thus kept con- stantly sore. The older ulcers may have the appearance of a diph- theritic membrane, being a dirty grayish color. It is usually a self-limited disease and may cover a period from 5 days to 2 weeks. There is a considerable doubt as to its etiology, but Holt* and Forchheimerf agree that it is of nervous origin, and not proved to be contagious. It is frequently associated with disturbances of the stomach and an attack may be coincident with the eruption of the teeth. Thrush is a form of stomatitis occurring in children and dependent upon the growth of a parasitic fungus. This consists of long, jointed threads, the saccharomyces albicans, which seem to belong to the family of the moulds. Thrush is undoubtedly contagious. If a little of the exudate from the mouth is treated with a drop of liquor potassae and examined with the low-power of the microscope, the structure will reveal the fine threads (the mycelium) and the small oval spores. Slight catarrhal stomatitis, inadequate salivary secretions and lack of cleanliness in the mouth will favor its development. Wherever many young children are congregated, as in asylums, nurseries, and foundling homes, all are liable to contagion of the disease. It is most frequently developed in children suffering from malnutrition or other wasting diseases, or from any deformities within the oral cavity, as hare lip and cleft palate. On looking into the mouths of young infants a layer of thin white patches, almost a mem- brane, may be seen covering the palatal arch and appearing as white spots upon the tongue, while the mucous membrane about or at the borders of this coating seems to be in a healthy condition. The white flakes cannot be wiped or brushed off; any attempt to forcibly remove them will induce bleeding. ♦Infancy and Childhood: Holt, 247. fArchives of Pediatrics, ix, 330. ORAL HYGIENE OF THE INFANT. I05 The preceding remarks are more especially applicable to infantile stomatitis. The same or analogous conditions may be induced in adults by like causes. Anemic and poorly nourished persons are especially liable to inflammations of the oral tissues. The lips are dry and parched, and superficial fissures and cracks in the mucous membrane appear. In a less degree this will be observable upon the tongue, the buccal surfaces, and in the vault of the mouth. This may continue for some time, until finally, with the progression of a general febrile state, a more active stomatitis is developed that may re- sult in a local breaking down or ulceration. Neglect of the teeth and mouth tissues is a fruitful source of sto- matitis in adults. Food is left to ferment and putrefy, and the products of this action will be exceedingly irritative to the soft tissues, as well as destructive to the hard. There will always be gingivitis present in the mouths of those who do not give proper attention to the removal of foreign substances from about the teeth, and this, by continuity of tissues, may spread all over the mouth. Usually the action of the saliva upon the portions freely washed by it is sufficient to keep them clean and normal. But between and about the teeth, where food remains for an indefinite time, in the absence of proper care the gums are always irritated and more or less congested, and this may spread to adjoining tissue, with the result of an acute stomatitis in atonic conditions. In infantile affections the very first measures to be adopted nec- essarily imply an inquiry into the food and feeding. If the child is artificially fed, the nursing-bottle should be carefully inspected, and the food that is given must be scrutinized. If there is anything un- sanitary about either, it must be at once corrected. The rubber nipple must be sterilized, or, what is better, discarded and substituted by a new one that has been made thoroughly aseptic. If the child is poorly nourished through improper or insufficient food, that must be remedied, and plenty of nutritious matter that can be readily digested and assimil- ated should be given. If there are diarrheas or other wasting disor- ders, which will too often be the case, they must at once be attended to; it will be impossible to build up a patient while any process of waste is going on. All unhygienic surroundings must be remedied, and the patient should be given plenty of light and air, and proper exercise. In short, beneficent Mother Nature, upon whom we must finally rely for a cure, must be afforded every opportunity. Functional activity must be promoted, and all obstacles removed. After securing perfect sanitation the local treatment will be mainly I06 HYGIENE OF THE MOUTH. depurative and stimulative. If a cathartic is indicated, two drams of castor oil may be administered. For the local irritation, a mouth wash consisting of a solution of five to ten grains of chlorate of potash to an ounce of water may be used as a mouth wash. If the child is too young to use this itself, a swab may be made by tying absorbent cotton to a stick of proper dimensions, and this may be used to apply the solution, employing a proper degree of friction. If the mouth is sore, it may be applied with a soft sterilized gauze — never use a soft tooth brush, it carries infection. The mouth may be occasionally washed out with the following preparation especially after eating: I^ — Borax, 30 grains. Sodium bicarbonate, i dram. Distilled water, ' 4 ounces. Or the following may be substituted in its place: J\ — Boric acid. Potassium chlorate, of each 15 grains. Lemon juice, I ounce. Glycerol, 6 drams. Never give syrups or honey to a child, because of fermentation. If there are deep erosions of the mucous membrane, or ulcerative surfaces, it may be necessary to cauterize them, either with silver ni- trate, pure phenol, or chromic acid crystals. The last named are pref- erable in instances in which they can be conveniently used. The cauterized places should be subsequently dressed with a solution of calendula. The treatment of follicular, or ulcerative, stomatitis in adults does not materially differ from that in infants, except that more active meas- ures may be used. The remedies may be proportionately increased in strength, and personal care insisted upon. The teeth should be thoroughly cleansed, and all broken or sharp edges removed. A soft tooth brush should be employed after every meal, only when a normal condition has been established, and with it should be prescribed some antiseptic wash. A two per cent solution of zinc chloride may be used as a gargle. At night a spoonful of milk of magnesia should be taken into the mouth and rinsed about all the teeth, to be left upon them until the morning. Enough of good nourishing food should be given, and the patient should have plenty of pure air and sunshine. In cases of thrush in infants that are badly or insufficiently nourished, there is usually more or less of gastric or intestinal irritation in con- nection with the markedly atonic condition. This will probably require the administration of such correctives as rhubarb and soda, DEPOSITS. 107 or lime-water. When the aphthae occur in older persons they are often spoken of as "canker spots," or "canker sore mouth." The usual treatment is roughly to cauterize the spots and dress them with a solution of calendula. If an active cauterant is not desirable, as in children, the aphthous patches may be repeatedly touched with the following solution: I^ — Sodium salicylate i dram. Distilled water, 6 drams. Or in place of the preceding this may be used I^ — Borax, 45 grains. Sodium salicylate, 75 " Tinct. myrrh, i dram. Distilled water, ^ ounce. The chlorate of potassium solution is strongly recommended. If the aphthae exist in considerable numbers, they may demand the use of antiseptic mouth washes. If they are the consequence of a general anemic condition, tonics and alteratives are of course indicated. While they are peculiarly uncomfortable, the aphthae have no serious patholog- ical signification, except as they are indicative of an atonic condition. DEPOSITS. Superficial deposits upon the teeth composed largely of inorganic precipitates have their origin from external sources, and most fre- quently are derived from the fluids of the mouth. In addition there are accumulations of organic detritus, as decomposing food, animal and vegetable; fermenting starches and sugars; advanced products of decomposition; waste and broken down epithelial cells from the mucous membrane, and myriads of benign and malignant micro-organisms. These combine to form a pasty and cheesy deposition, which is found about the cervical margins of the teeth and gums. This mass is not in the nature or form of a calcareous tartar, and is easily removed by the frequent and habitual use of the tooth brush and waxed dental floss. It is not always necessary to use a tooth powder every day, for once the teeth have been properly cleaned by the careful dentist, it be- comes comparatively easy for the patient to keep the mouth free from this debris. It must be emphatically stipulated, however, that these products of decomposition should be daily removed by the patient. Io8 HYGIENE OF THE MOUTH. In addition, if necessary, the dentist should insist upon seeing his patient at frequent intervals until there shall have been established con- ditions that indicate a normal, healthy mouth. No amount of filling and restoring of defective teeth will ever suffice to maintain a healthy mouth so much as the unremitting care and removal of these organic deposits. The elimination and pre- vention of caries is dependent upon the destruction of the micro- organisms of decay, and the removal of their acid products which are so destructive to enamel and dentin. The action of these organic deposits is not always readily appreciated. The destructive effects of the acid products are seen in the interproximal spaces and angles formed by overlapping teeth, or where teeth have been extracted, leav- ing the space to be filled in by the unsupported teeth, which cause a tipping forward, thereby forming triangular pockets lodging food and debris. The enamel may be quite thin at the points of contact in the interproximal space and universally so, yet not show an active break in the continuity of the surface. This accounts for the apparent rapid destruction of the teeth, when in reality the destructive process has been going on for years, the habit of leaving the teeth uncleansed from breakfast time, through the day, until retiring at night, is a pro- lific source of enamel decalcification. Green stains are among the simpler deposits found upon the teeth of young children as well as adults, particularly in the region of the cervical margins. These stains are wholly superficial and vary in color from a dark green or bronze to yellow. They are not indicative of any special pathological disturbance, only in so far as they denote an undesirable condition in the oral secretions. Their early removal is advocated, because they are claimed to be from a disease producing fungus which, if neglected and allowed to remain, will penetrate the enamel, and so erode the surface as to form a series of granular pits which ultimately combine to form a distinct cavity. Erosions of the enamel surfaces frequently have their inception through the agency of the green stain deposits, and wherever there is a congenital weakness in the enamel, as in faulty structure of the enamel prisms, having soft white spots of calcification immediately adjacent to the interglobular spaces of the dentin, then erosion and decalcification and rapid destruction of tooth substance quickly follow. Other stains found upon teeth are those deposits caused by the excessive use of tobacco and tea, and sometimes from the use of medi- cines. Except from the unclean appearance produced by these latter DEPOSITS. 109 Stains, there appears to be no immediate injury to the enamel surfaces in consequence. It is important, however, that they should be re- moved; this may be done readily by touching the stained area with a small amount of tincture of iodine then scouring with English precipi- tated chafk. If the surface is eroded and roughened, it must be dressed down smoothly with cuttle bone, or fine Arkansas stone and finally polished with chalk. The salivary calculus, and the calcareous accumulations being deposited about the neck and roots of teeth, cause recession of the gum tissue and inflammation of the peridental membrane; these are among the most important of the deposits, because the neglected accumulations induce diseases of the gums and adjacent tissues, and although local and superficial in deposition may be the precursor of more serious disturbances. The salivary calculus is a deposit from the saliva. The calcium salts are held in solution through the agency of the carbon dioxide (CO2) present in the newly elaborated saliva. This fluid is poured into the oral cavity where it encounters acids derived from a variety of sources, and is subjected to the action of the ferments from decom- posing foods. The quantities of saliva are more or less variable; this is also true of the calcic salts contained in it. The carbon dioxide (CO2) is held in a very unstable solution, and upon exposure to the oxygen of the air and contact with the acids in the mouth, derived from various sources, the carbon dioxide (CO^) is liberated, the calcic constituents lose their solubility, form precipitates upon the teeth, and give rise to what is commonly called salivary calculus or tartar. Combined with these calcium salts are products of organic decompo- sition, which cause the tartar to become a powerful irritant to the gum tissue, and induces inflammation in the contiguous tissues. The deposition of salivary calculus is mainly in the region of the mouths of the salivary ducts, as Wharton's duct and the duct of Steno. The greater amount is liable to accumulate upon the lingual surfaces of the lower incisors, and opposite Steno's duct, upon the buccal surfaces of the upper molars. One of the predisposing factors in the accumulation of large pre- cipitates of tartar is found in the fungoid growths and deposits upon the teeth, made up largely of partially decomposed food and threads of the higher bacteria, as the leptothrix or streptothrix actinomyces. The protoplasm of the filaments of these organisms breaks up into bacillus-like elements, and all combine to form an agglutinating mass, which holds the precipitates of calcium and becomes a nidus for a no HYGIENE OF THE MOUTH. concretion. And although the mouth has been kept free from these organic bodies, it is possible to find a foundation for holding tartar deposits in the saliva itself, which is a mixed fluid derived from the secretions from the oral mucous, parotid, sublingual and submaxillary glands. These secretions are subject to considerable variation, both in physical as well as in chemical character. Ordinarily, saliva is a clear, viscid fluid, at times thin and watery and at other times thick and ropy. According to Michaels, it contains all the salts of the blood which are dialyzable through the salivary glands; this offers a fair index of the metabolic processes being carried on in the entire system. There are times when the viscid and tenacious quality of the saliva with its mucin constituents becomes dried upon the teeth, form- ing masses of sordes (Marshall) ; this, together with the debris of epi- thelial cells, mucous corpuscles and salivary corpuscles offers a favor- able nidus for tartar deposits. CHEMICAL COMPOSITION OF SALIVA, The chief constituents of a normal mixed saliva are ptyalin — a diastatic ferment — mucin, and the chlorides of sodium and potas- sium. In variable quantities traces of albumin, fat, potassium sulphocyanide, sulphates and phosphates of the alkalies and alkaline salts, as the calcic phosphates, calcic carbonates and oxide of iron may be found; occasionally also traces may be found in normal saliva of urea and ammonium nitrate. "The source of origin of the saliva that contains these chemical constituents is from the blood, or more correctly from the plasma, which is filtered off from the circulating blood into the interstices of the glands, as of all living textures." In reaction the saliva when first secreted is slightly alkaline. Dur- ing fasting, although secreted alkaline, it soon becomes neutral. Tests of saliva with litmus paper frequently give an acid reaction, and this may be due to the elaboration of acids from foods, ferments and bacteria. Tomes gives the daily average of the amount of saliva excreted from 800 to 1500 grams, approximately from three pints to a little less than a quart. Lehmann has estimated the specific gravity of saliva in health as ranging from 1004 to 1006, and states also that there may be a rise as high as 1009 and a fall as low as 1002, without the evidence of any existing disease. CHEMICAL COMPOSITION OF SALIVA. Ill Frerichs* gives the following chemical composition of mixed saliva: Water 994.10 Solids: — Ptyalin 1.41 Fat, 0.07 Epithelium and proteids (including serum-albumen, globulin, mucin, etc.) 2.13 Salts: — Potassium sulphocyanate Sodium phosphate Calcium phosphate Magnesium phosphate Sodium chloride Potassium chloride .2.29 5-9 1,000.00 The excretion of the parotid gland contains slightly more water than the secretion from the submaxillary and sublingual glands, and in consequence is less viscid. It is rich in ptyalin, but contains no mucin; its calcic constituents are the carbonate and phosphate, the latter existing in minute quantities. According to Hoppe-Seyler the inorganic elements yield about 0.34 per cent.f The secretions of the sublingual and submaxillary glands are poor in ptyalin but rich in mucin; the sublingual contain the higher per cent. Carbonate and phosphate of calcium yield about equal propor- tions. These elements amount to about 0.43 per cent in the sub- maxillary secretion, but the precentage is not so high in the sublingual. Mucin is derived largely from the mucous glands, and the organic and inorganic constituents average about 20 parts to 1,000. Berzelius estimates the composition of salivary calculus as follows: Phosphates of calcium and magnesium, 79.0 Sah'vary mucus, 12.5 Ptyalin, i.o Animal matter soluble in HCl 7.5 Calcic deposits from whatever source should be removed, and inflammations of the gums and mucous membrane of the mouth irre- spective of their origin must be relieved and resolved into healthy tissue. It does not necessarily follow that because we find large deposits of tartar upon the necks of the teeth that we have the disease of pyorrhea alveolaris. We have seen many patients whose teeth have been neg- lected, and who were innocent of the smallest effort on the part of a ♦Kirkes' Handbook of Physiology, 1893, p, 295 t Marshall Op. Dentistry, 523. 112 HYGIENE OF THE MOUTH. dentist in all their lives as to removal of the deposits, which were ex- cessive, and to whom the use of a tooth brush was unknown, yet, upon the careful removal of these deposits and orderly and habitual use of the brush, the mouth was quickly restored to a healthy condition. The deposits in some instances have been exceedingly thick, and upon the lingual surfaces of the lower anterior teeth an aggregation of successive layers has formed, that completely bound the teeth to- gether as in a plaster cast. The encroachment, however, does not always extend very far below the gum, nor necessarily involve de- struction of the peridental membrane. An early treatment of such conditions, to be described later, results in complete restoration with- out the accompaniment of the disease designated pyorrhea alveolaris. SERUMAL DEPOSITS. It is not the purpose of this part of our work to treat exhaustively the various authoritative opinions as to the etiology of the serumal deposits. We shall consider, however, a few of them in so far as to present a general summary that will guide us in recognizing these deposits which call for special treatment in their removal. The sub- ject has been considered more completely in the chapter on pyorrhea alveolaris. Dr. John Marshall,* in 1891, said, "That the deposition of the concretions upon the roots of the teeth in those localities not easily reached by the saliva, or in which the presence of the saliva would be an impossibility, is due to the causes which produce the chalky for- mations found in the joints and fibrous tissues of gouty and rheumatic individuals." Dr. G. V. Black has done considerable research work and has written an exhaustive paper, published in the American System of Dentistry, Vol. I, p. 953, wherein he speaks of a calcic inflammation and phagedenic pericementitis as an accompaniment of the tartar de- posits upon the teeth in the region of the peridental membrane, and though he indicates his belief that the cause is wholly local, he also admits that a sanguinary deposit may be closely involved in its origin. He differentiates it as a destructive inflammation of the pericemental membrane, distinct from other inflammations of this tissue though possessing features in common with them. In summing up his esti- mate, he concludes that the disease is essentially one of the peridental membrane rather than of the alveolus, and the destruction of these ♦Transactions American Med Assoc, 1891. SERUMAL DEPOSITS. II3 two Structures is so nearly synchronous that it becomes difficult to say which has gone first. Dr. C. N. Pierce * gives the name ptyalogenic calcic pericementitis to the conditions wherein the teeth are involved with calcic deposits, indicating, as he believes, the origin of these deposits and other calculi as traceable to the saliva. We are not concerned particularly in this section of our paper with the cause so much as in adequately recog- nizing the conditions in the mouth that call for treatment, and the establishment of a sound oral hygiene. W. C. Barrett t has summarized the theory of E. C. Kirk on the formation of serumal calculus as follows: "The capacity of the blood stream for holding in solution the waste products of nitrogenous metabolism, the results of functional activity in the body, is determined by the alkalinity of the blood plasma. Any decrease in this diminishes its solvent power for these, and causes their precipitation in the tissues nourished by the blood stream. This lessened alkalinity may be general, affecting the whole sanguinary current, or it may be localized in certain tissues; in the latter case there will be a localized precipitation of the products of which uric acid is a type. Excessive work causes an increased blood supply to a part, and excessive oxidation and tissue waste, which in turn produce lessened alkalinity, or a tendency toward acidity. The ligamentous tissues are especially liable to conditions of this nature, and the peri- dental membrane, belonging to this category, is especially subject to "affections of the character noted. Excessive work being put upon the investing membrane of any tooth, through malocclusion or by bad habits in mastication, by injuries from v^^dging, the application of ligatures, or other causes, the resulting hyperemia brings in its train overnutrition, localized diminished alkalinity, with the consequent deposition of urates." We have thus considered those superficial deposits found upon the teeth having their origin from organic debris and the saliva; it remains to briefly differentiate those which form upon the roots of the teeth primarily, and are commonly designated sanguinary calculus. Its characteristic appearance is somewhat different from the salivary calculi, although these latter may, through a considerable period of successive depositions, become in time a dense, black, smooth supra- gingival deposit, having incorporated through the agency of pigmentary matter, oxides from amalgam fillings, and the action of medicines, *Am. Text Bk. Op. Dentistry, 2d Ed., p. 510. fOral Pathology and Practice: Barrett, p. 139. 8 114 HYGIENE OF THE MOUTH. which may cause it to assume the external color and appearance of the sanguinary calculus. The location of these deposits would indicate their entire independ- ence in formation of the oral fluids, as they are found precipitated upon the periphery of a root that is not denuded when formed, and where there is no destruction of the gingival border. It is distinctly more irritating to the tissues than the smooth amorphous deposits from the salivary calculus, and this may be due to its position within the alveolar socket where it is preeminently a foreign body. The deposi- tions are not in uniform amorphous masses, but appear as separate minute nodules, which cling tenaciously and are with considerable difficulty removed. Successive aggregations unite to form a mass that is hard and brittle, whose color is olive black or olive green. It is unlike the salivary calculus which may be readily detected, and is therefore easy of diagnosis, as it is hidden away within the socket, sometimes beyond a point of accessibility for its removal. The removal of deposits, whether of salivary or serumal origin, demands the highest skill and care in the use of specially designed instruments for this operation. No hurried and indifferent service rendered the patient will ever restore the oral tissues to a normal con- dition; this result is obtained only by deliberate painstaking care, combined with intelligent work. The selection of proper instruments must be determined not by any arbitrary rule, but according to the requirements of the operation to be performed, and the writer has obtained the best results from a composite set selected from the admirable instruments designed by Doctors Kirk, Darby-Perry, King, Marshall, Abbott, Harlan, Smith, S. S. White Manufacturing Company, and J. W. Ivory. The instruments should be clean and sterilized, and everything about them suggestive of care. The patient should be comfortably seated, and the chair inclined and head-rest adjusted in order to have the mouth receive the largest amount of light possible. All napkins, large or small, must be fresh and clean. The larger napkin should be sufficient to protect the patient's clothing from flying particles and loose debris. Ordinarily the operator stands firmly on the right side of the patient with his left arm around the head-rest, and by this means is in a position to gently steady the head. Small rectangular pieces of sterilized gauze from 4x4 inches to 5 x 5 inches are most use- ful in receiving the soft deposits as they are spooned off. A small piece of gauze should be rolled and placed between the lower lip and gums to prevent pressing the septic matter into the delicate membrane of SERUMAL DEPOSITS II5 the lips. The lips may become infected and considerable swelling be induced by lack of care on the part of the operator. In order to lessen this liability it may be necessary to prescribe a suitable mouth wash and special application of the tooth brush for a few days preced- ing the operation of removing the debris. Where conditions are ab- normal, this precautionary treatment is of value in preventing further inflammation. The left hand should hold the mouth mirror, which serves the double function as a tongue depressor and light reflector. The eye of the operator should always follow the scaling edges of the instrument as near as possible, and whether the movement is a drawing upward or pushing downward, the scaler should be so held and supported by the fourth and fifth fingers resting upon the adjacent teeth, that there shall be no danger of a slipping and plunging into the tissues of the gums. When a deposit has been definitely located and dislodged, it should be immediately removed and accounted for. It may be necessary to frequently syringe the tooth and membranes with a warm, antiseptic mouth wash in order to facilitate the complete elimination of all foreign irritants. Whenever there are indicated deposits below the gingival margin, it is well first to remove carefully the superficial deposits upon the sur- faces of the teeth above the membranous tissues, beginning at the central incisors and cautiously working round the arch to the third molars, each half of the mouth being treated successively until all the teeth have been scaled. The time necessary for this operation will depend somewhat upon the conditions presented, and it may be necessary to resume the operation at a future time. During this pre- liminary scaling, mental note should be made of the pockets formed between the roots where debris and calcic deposits accumulate; minute congestion of the gingiva; triangular spaces and irregularities as a result of inclined crowns, and any other factors predisposing and favorable to the accumulation of deposits, as cavities through caries, furrows between the cervical enamel and cementum; hypertrophied tissues; eroded cement fillings; rough and pitted gold fillings and sur- faces; projecting amalgam and other fillings; improperly fitting clasps, artificial dentures and gold crowns. All supragingival surfaces should be most scrupulously scaled, cleaned and polished as a preliminary operation to further removal of the subgingival accumulations. It matters not who may be responsible for the old restorations, it is a necessity that the roughened fillings and surfaces be cleaned and polished. Il6 HYGIENE OF THE MOUTH Incidentally, the patient's attention may be directed to certain localities within the mouth where there is a special tendency for the retention of decomposing foods. Subgingival deposits invariably induce distinct pathological con- ditions within adjacent membranes, and each tooth carrying upon its surfaces and roots these foreign bodies should be treated individually, until all trace and evidence of their presence has been removed. The tenacity with which serumal deposits cling may call for the use of a softening agent, and a twenty per cent aqueous solution up to fifty per cent of trichloracetic acid may be used with beneficial results. The percentage strength of the acid necessary is to be determined by trial. The acid is carried into the region of the deposit, either upon a wedge-shaped piece of orange wood stick or upon a few fibers of cotton soaked in the acid. A gentle pumping motion will suffice to reach the nodular deposits. Lactic acid has been recommended for the same purpose with claims for its therapeutic value. We are now using with beneficial results a solution of bifluorid of ammonium, a formula advocated first by Dr. Joseph Head (see Dental Cosmos, Jan., 1909). He says: "This medicine primarily attacks the bond between the tooth and tartar, making easy the removal of large lumps by instrumentation. It also dissolves the microscopic particles of calculus that have been undiscovered by the scalers. "It seems to be even more active therapeutically than chemically, since a drop or two placed in a pyorrhea pocket will not only loosen what tartar is present, but will stimulate the soft tissues to a healthy reorganization and readherence to the tooth. Even where no deposit of calculus is found on the root within the pyorrhea pocket, weekly applications of this solution will cause readherence of the gum and a consequent tightening of a tooth that was formerly loose. This phenomena is explained by the fact that a chemical solvent of tartar will attack the crystals of urate of calcium that may exist in the diseased peridental membrane. >'» "The bifluorid solution when injected into a chronic fistula will cause rapid, and in many instances permanent, healing by dissolving the organic matter of the dead bone and stimulating the living cells to healthy action. This should, however, be done with caution, only a minim or two being used as a dose, since too large a quantity will cause excessive stimulation and pain which may last for hours with considerable swelling. This is explainable by the fact that fistulas sometimes lead to large internal bony cavities and if these are filled SERUMAL DEPOSITS, II7 full, an excessive dose is given to the patient. This, however, if it causes pain also causes rapid healing, and it is the author's experience never to have known a case where a large dose did not result in a cure corresponding in quickness to the extent of the pain occasioned. However, smaller doses are to be advocated, as these give satisfactory results and can be obtained with little if any discomfort. "As the bifluorid solution attacks glass, a celluloid or rubber syringe with a platinum point is advisable for its application. For this purpose the bulb syringe with the celluloid barrel and platinum point, made by Dunn & Co. of Chicago, is excellent. There is a plunger syringe composed of celluloid that is also excellent. It was invented by Dr. C. D. Beedle of Leominster, Mass. "There are various quill applicators, but these do not give the best results as the medicine reaches the bottom of the pocket in a diluted condition, whereas, if the syringe point is carried to the bottom of the pocket and slightly withdrawn, the entire pocket can be filled, the undiluted solvent being placed at the deepest point where it is most needed. "It is a curious fact that the more times a patient receives an ap- plication of the bifluorid, the less it irritates the gums, although the therapeutic effect is not diminished. Some patients can stand the application without pain or discomfort for four or five minutes, the average can bear it from one to two minutes, a few can stand it only for a few seconds, when the mouth should be immediately rinsed with water, which is all the neutralization that should be used where the therapeutic effect of the drug is to be obtained in a continuing effect. Where, however, too much irritation is experienced through lack of caution in its application, the rinsing of the mouth with milk of magnesia will rapidly reduce the sensitiveness, although, as before stated, the therapeutic value of the application will be rendered negative. " Bifluorid of ammonium is sold under the trade name of Tartsol and is for sale at the S. S. White Dental Mfg. Co." The chiseling and scaling and applications of the acid may be re- peated until all the nodules are removed, and the roots are clean and smooth. Care must be exercised not to lacerate the tissue of the gums and peridental membrane. The force employed should be well under the control of the operator to avoid destruction of the cementum, and unnecessary loosening of the tooth. Too murVi movement of the tooth within the alveolar socket is liable to carry granules of calcific deposits and septic matter further into the pocket and tissues. Should the Il8 HYGIENE OF THE MOUTH. teeth be very loose, a temporary supporting splint, made of softened modeling compound, and applied to the labial surfaces of the teeth en masse, when the lingual surfaces are under treatment, will be an effective and agreeable support; the reverse application when the labial surfaces are treated. Frequent syringing with a warm antiseptic mouth wash, such as phenol sodique or peroxide of hydrogen (H^Oj) three per cent solution, to remove debris is necessary. The author counsels against a too early application of massaging of the gum tissues, because of the danger of incorporating within the tissue loose deposits that become a continual source of irritation. This operation may be deferred until later when all trace of inflammation has disappeared, and careful exploring reveals no deposits. Ultimately, a weak solution of zinc chloride may be worked into the pockets as a stimulating astringent. New vitality may be induced, bringing new granulations to the alveolar edges by scraping with a bur or hoe excavator. The treatment should end when all is clean, and there is an eflfusion of coagulable lymph, which should be left and not washed or wiped out, because at this point nature can accomplish much in the restorative process. The dentist should determine for his patient how soon this op- eration should be repeated, and that will be governed by keeping a careful record of the status of the case with treatment and results for future reference. CHAPTER VI. DENTAL CARIES. BY C. N. JOHNSON, M.A., L.D.S., D. D. S. In a work like the present it is deemed unnecessary to go minutely into the pathology of this disease and yet it is well to consider some- what carefully certain of the etiological factors which affect us vitally in operative dentistry. Every operator who attempts to save the natural teeth should have a reasonably clear conception of the cause or causes of caries, of its modus operandi, and the peculiar methods of its attacks. If he is thoroughly informed on these points he will be in a position to do better work thereby, and recognizing this the foremost men in the profession have always sought to inform them- selves in regard to these matters. Some of the theories of the past have been so wide of the mark that they are interesting only as milestones along the uphill road of scientific progress, while others, though crude and lacking in demon- strated data, are worthy of the greatest respect in the light of the most recent knowledge. Certain writers have held the theory that inflam- mation played a part in the breaking down of the tooth tissue, that the character of the tooth structure itself was the most significant thing connected with it, and that the disease progressed from within outward. Others thought that while the disease began upon the surface of the tooth and progressed inwardly it was due chiefly to the chemical reaction of the saliva, that in fact it was acid saliva which produced the decay. But it was inconceivable to think that the saliva ever became sufficiendy acid to eat into a tooth in the manner in which we find caries progressing, or that the soft tissues could tolerate it if it did. Not only this but if the saliva did the work we would find the teeth attacked uniformly upon all surfaces bathed in saliva while as a clinical fact there are certain surfaces in which decay seldom or never has its initial point of entrance. Some of our close observers noted these thirgs and away back as far as 1828 Robertson indicated that the carious process was due to the action of some agency occurring immediately at certain points where cavities were to begin, his idea being that it was caused by "decomposition." This theory was of course vague as to the real active agent of caries, but it was correct 119 I20 DENTAL CARIES. in the principle that it was localized at certain points and was not general in the fluids of the mouth. There was much conjecture about the whole question of the active agent of caries till Professor W. D. Miller demonstrated in 1884, that it was due to the formation of acid brought about by micro-organic growth in the mouth. The findings of Miller have stood the test of investigation since then, and while there are many factors in the development of this disease which we do not yet quite understand, still they gave us the first real basis of scientific knowledge to work from. In a somewhat close clinical observation of the behavior of caries, the variation in its manner of attack, and in its general modus operandi in different cases, it is hard to conceive that it is always brought about in the same way or that its progress is invariably governed by the same conditions. That an acid causes the solution of the tooth tissue seems settled, and that this acid is the product of micro-organisms is also an apparently accepted fact. But why is it that we find such a variation in the manifestations of the disease in different mouths, and even in different periods in the same mouth? We may find micro-organisms in all mouths — in fact the very micro-organism which Miller demon- strated would bring about decay, and decay which could not be dis- tinguished from that occurring in teeth in the mouth — and yet there are some mouths in which decay never occurs, and in most mouths where it does occur there is a great variation in its virulency at different times. It was formerly the prevalent idea that these variations were due to differences in the tooth structure, that one tooth was harder than another and would therefore withstand the attack of the carious agent better, and this impression was so strong in the profession that it finally communicated itself to the laity and is still firmly fixed in their minds. It is common to hear patients say that their teeth are so soft that it is almost impossible to save them, or on the other hand that they are growing harder so that they do not have so much trouble with them as formerly. This has been a most difficult fallacy to dislodge from the minds of the profession, and it has been the means of the loss of a very great number of teeth which otherwise might have been saved. The impression that the teeth are inherently so defective in structure that they are thereby peculiarly susceptible to the attack of caries is very disheartening, and it has led many patients to abandon any effort to save them and to allow them to go by default. This impression has too frequently been fostered by members of the pro- fession, whose function as teachers of the public should have made them guard against such false and harmful doctrine. DENTAL CARIES. 121 It is now more than ten years since the investigations of Dr. G. V. Black demonstrated conclusively that there is really little variation in the chemical constituents of the teeth of different individuals, and that what variation there is has little or nothing to do with the inception of dental caries. This came as almost a revolutionary statement at the time but his findings have never been disproved. Neither do the teeth of individuals grow harder and softer in any such sense as would account for the variations we see in the same mouth in the tendency to decay at different periods. Teeth grow slightly harder as age advances but this change is exceedingly slow and not of a character to affect the manifestations of caries. This is readily under- stood when we recall the fact that the teeth are the most stable organs of the human body, and are not being constantly torn down and built up by w^aste and repair as are other tissues. And yet the impression in the profession that some teeth were very much harder than others was a perfectly natural one,, owing to the difference in behavior of teeth under cutting instruments. This difference could not escape the attention of the most careless observer. Some teeth crumble away under chisels, excavators and burs, as if composed mostly of chalk; while others resist the attack of steel instru ments almost to the point of striking fire. This led to the impression of varying softness and hardness in the teeth, and quite naturally to the conviction that this had a direct bearing on the tendency to decay. But there is another reason to account for the difference in behavior of teeth under instrumentation, and it is in accordance with close clinical observation that these same so-called "soft" teeth sometimes remain in the mouth for life free from caries while the "hard" teeth as frequently decay. It simply resolves itself down to a question of environment — the conditions which surround the teeth — rather than to the organic structure or constituents of the teeth themselves. The reason that teeth vary in their resistance to cutting instru- ments is limited almost wholly to the enamel and is due chiefly to the arrangement of the enamel rods. In some teeth the rods stand nearly parallel and radiate outward in regular order from the dentin in a comparatively straight line. It is noteworthy that in any enamel the cement-substance which holds the rods together is not very strong and the enamel is easily cleaved in line with the rods. It will thus be seen that straight-grained enamel like this will break down readily under instruments. But there is other enamel in which the rods pursue a wavy course, and a section of which looks something like the structure of a gnarled oak. When a chisel is directed against 122 DENTAL CARIES. such enamel as this it meets the stout lateral resistance of the rods themselves and is broken down with exceeding difficulty. But there is no enamel formed in the mouth of man which the acid of decay is not capable of dissolving if the conditions are favorable to its development, and so all enamel is alike subject to the attack of caries. This one difference may be noted that when decay has once begun it is reasonable to suppose that it will progress more rapidly in enamel where the rods stand straight so that the acid can have ready entrance between them than it will in wavy enamel where the access is less easy, though this has no relation to the question of the liability of the teeth to the original inception of caries. If, then, it is a matter of the conditions surrounding the teeth which chiefly influences this disease, it is imperative that we study these conditions somewhat carefully, and herein, be it said, lies the future hope of the profession in controlling and ultimately in preventing a disease which is acknowledged as being the most prevalent of all diseases of the human race. Had it been a question of the tooth structure there would have been small hope because we have learned that when once developed we cannot change that, but being a question of condition we may reasonably expect in time to so control the sur- rounding condition as to limit the disease. First it is necessary to learn what the conditions are which influence the inception of decay. We have said that the micro-organism of caries may be found in all mouths; then the natural query is, why do we not find decay in all mouths? What is the particular agency which makes it possible for the micro-organism to bring about caries in one case, and impossible in another? Dr. J. Leon Williams, and Dr. G. V. Black have called attention to what they consider an important factor in the institution of caries, viz., the formation of gelatinous plaques on the surfaces of the teeth. We know that there are certain micro-organisms which in the process of their development produce a material closely allied in appearance to gelatin, and these are called gelatin-forming micro-organisms. The micro-organism of caries is one of this class, and it is the opinion of Williams and Black that it is mainly through the agency of these plaques that cavities are formed. It is of course known that an acid in order to dissolve enamel in the way we see it in the mouth must be a strong acid, and unless the micro-organisms have some protection under which to work, their acid would be diluted very quickly in the fluids of the mouth, and thus their destructive process be interfered with. It is therefore the idea of these investigators that it is by virtue of the protection given the micro- DENTAL CARIES. 1 23 organisms through the formation of gelatinous plaques that the begin- nings of decay are brought about. A film is formed on the surface of the enamel and under cover of this the micro-organism may produce its acid in concentrated form and attack the enamel undisturbed by external interference. In fact Dr. Williams has been able to make ground sections of teeth thin enough for microscopical examination, showing the film in place with rhe micro-organisms under it and decay beginning in the enamel. Of course, after a cavity has once been started the micro-organisms have a sheltered place in which to work and do not need this gelatinous protection, but it is in the inception of caries that it plays an important role. This film is not soluble in the fluids of the mouth nor is it easily dislodged when firmly attached. No rinsing of the mouth with liquid will affect it, and it takes appre- ciable friction with a tooth brush to dislodge it. The saliva may therefore flow freely over its surface without disturbing it, and even the most potent of the mouth washes yet devised will not dissolve it. In this view of the case it is concluded that the significant thing in dental caries is the formation of this film, and that it is really the controlling factor in the question of immunity and susceptibility. In some mouths the conditions seem favorable for the production of these plaques, in others not, and upon this the issue is turned. In referring to plaques it must be remembered that a distinction should be made between these gelatinous plaques and patches of inspissated mucus and greasy masses of material left adherent to the surface of enamel through neglect in caring for the teeth. Dr. W. D. Miller in writing on this subject seems to place less significance on the film than Williams and Black, and claims that the case is not yet proven. He says that we may find these films freely in mouths where there is no decay, and that we may also find cavities without the presence of a film. In the latter instance he admits that the absence of a film after a cavity has started is no evidence that it may not have been there in the beginning. In point of fact we have had just sufficient knowledge on this sub- ject to make it imperative that we have more. As has already been intimated the behavior of some cavities is so entirely different from that of others that it is hard to conceive that they are all influenced by the same factors, and it is hoped that further investigations along these lines will give us a broader view of the whole question, and clear up some of the points which at present seem somewhat clouded. But what concerns us most at this time are the clinical manifes- 124 DENTAL CARIES. tations of immunity and susceptibility as we meet them in our every day practice. Dr. Michaels of Paris in studying the manifestations of susceptibility and immunity, took the ground that they were largely influenced by the condition of the fluids of the mouth, and claimed that in all cases of high susceptibility to dental caries there was a superabundance of ammonium salts in the saliva and an absence of sulpho-cyanatcs, while in immune mouths there was a diminution or an absence of ammonium salts with the presence of sulpho-cyanates. More recently Dr. F. W. Low of Buffalo, N. Y. has practically con- firmed Michaels' findings, and goes one step further in an effort to control the tendency to caries. In cases of great susceptibility he has been administering the sulpho-cyanates to patients with what seems to promise success in arresting the tendency to decay. It is hoped that these investigations will lead to something definite in the way of controlling this disease. A close observation of the phenomena of caries in the average susceptible mouth will disclose the fact that there are certain times when the disease is much more active than others. The periodicity of dental caries may be studied with much profit by the dentist, with the result that he is better equipped to manage the cases that come to him and more encouraged to persevere in the face of an apparently hopeless condition where the active agent of caries seems to be running rampant over the entire number of teeth in a given mouth. It is very rare indeed where the progress of this disease goes on uninterruptedly to the destruction of all the teeth in a mouth even when no attempt is made to arrest it, and much rarer in the event of any effort being put forth on the part of the dentist and the patient toward its control. That this is true is sufficiently evident from the large number of cases seen in practice where some of the teeth have been lost many years previously while the rest are being preserved with very little tendency to decay. The lesson of this is that if we can carry a case through a period of great liability to decay we may reason- ably expect a period of immunity to come sooner or later and with this to aid us in our efforts we may confidently hope to save the teeth for a lifetime so far at least as decay is concerned. One very significant fact in this connection is worthy of especial note — a fact embodying the greatest encouragement and carrying with it the highest incentive to persistent and painstaking effort on the part of the dentist. This is the assurance, established by a very close clinical observation in the study of cases extending over many years, that the period of immunity may be advanced very materially DENTAL CARIES. 1 25 by proper dental service at the time of greatest susceptibility. In other words when a dentist is struggling with a discouraging case of caries, endeavoring to keep the teeth free from deposits and insisting that the patient does his part in this work, when he is filling cavities which develop with disheartening frequency and repairing fillings that have failed, he may be assured that the result of his efforts does not stop with the teeth he is operating on, but that in his attempt to suppress decay he is changing the conditions in this mouth and establishing a state of immunity which will eventually aid him materi- ally in saving the teeth of his patient. With this view of the case no dentist should lightly yield up decaying teeth to the forceps, nor should he become discouraged however prevalent decay may be in the mouth. There are exceptions to all rules in practice, and there are some mouths in which the tendency to caries seems to persist for a disheartening length of time, but in the average case the results are so very gratifying that it is well worth the effort of both operator and patient to follow up a line of treatment tending to its suppression. Recent investigations of such men as J. Sim Wallace, and H. P. Pickerill would seem to indicate that the matter of diet 'is a very important factor in controlling dental decay. Wallace after a close study of the effect of diet on dental decay emphasizes the necessity of a diet containing fibrous foods which stimulate efl&cient mastication; and sums up his observations by outlining two diets, one of which is supposed to inhibit decay and the other to encourage it. In his book "The Prevention of Dental Caries," page 32, he says: Firstly, we shall refer to the kind of meals which do not produce caries : — Breakfast. — Fish, bacon, toast and butter, coffee and tea. Luncheon. — Meat or poultry, potatoes, salad, baked bread, pud- ding, fresh fruit, water. Supper. — Rusks, toast, or bread, rolls and butter, chicken or fish, an apple, tea or coffee. Secondly, we may outline the kind of meals which induce dental caries : — Breakfast. — Porridge and milk, bread and marmalade. Then perhaps a supplementary breakfast a few hours after of a glass of milk and a sweet biscuit. Luncheon. — Mashed potatoes and gra\7, or minced meat, milk and pudding. Supper. — Bread soaked in milk, or bread and jam, cocoa and 126 DENTAL CARIES. cake, and a supplementary supper on going to bed of a glass of milk and biscuit, or just a 'tiny piece of chocolate.' "On comparing these two different types of diet, we observe that one is of a kind which stimulates mastication and the last thing taken leaves the mouth clean, or at least free from carbohydrates, so that even when soft food is part of the meal the mouth will be physiolog- ically clean at the end of the meal. The other type is intended to represent the other kind of meal which is calculated to lodge about the teeth and to ruin them in a few years by making efficient masti- cation and the self-cleansing of the mouth practically impossible, and by leaving the mouth sticking with fermentable carbohydrates and a virulent crop of acid-forming micro-organisms which have had their development encouraged by the previous meal." Pickerill in his book "The Prevention of Dental Caries and Oral Sepsis," lays great stress on the advantage of articles of diet which may be classed as "Salivary Stimulants." To develop a condition of the saliva inimical to the incidence of caries it is necessary to use acids in the diet, a seemingly strange phenomenon but one apparently borne out by fact. He says: "What is therefore to be advocated is that all meals should con- tain a fair proportion of salivary excitants, and more important still, should both commence and end with some article of diet having an acid reaction r This teaching of Professor Pickerill is almost revolutionary so far as popular opinion is concerned. It has always been the prevalent opinion that the eating of acid substances was detrimental to the teeth, and yet Pickerill proves that the mastication of acid fruits puts the secretions of the mourh in the best possible condition to combat caries. His suggestion as to diet is as follows: — Breakfast. — Porridge with salt may be used, followed by any- thing customary, fish, bacon, bread and butter, marmalade or jam, the latter should be of a distinctly acid flavor. Conclude with some form of fresh fruit, orange, apple, pineapple, banana, pear, plum, etc., preferably raw, but may be stewed. Luncheon. — A radish or small portion of some acid fruit as an initial salivary stimulant, meat, with sauces, which are nearly all acid and serve as excellent salivary stimulants. Fruit (stewed) and fruit pudding or pie, made not too sweet, and fruit predominating over the starch element. Salad.* Tea. — May include as salivary stimulant, tomato, cucumber, cress, DENTAL CARIES. 1 27 sardines, shrimps, fruit or sandwiches. Fruit salad or any fruit in season should terminate the meal. Last thing at night children (and adults, too) should always eat a small portion of some detergent and acid fruit, such as orange, apple, pear, or pineapple. Tea and coffee, with cake, biscuits, etc., are not good as terminations to any meal. Milk, water, weak lime and lemon juice, slightly sweetened, are the beverages suited for children." The testing out of all these theories requires time, but the efforts of earnest men all working to the same end must eventually result in a reasonable control of this disease. The period of greatest susceptibility to dental caries is in youth, and it is here that our best endeavor in controlling decay should be put forth. If we can successfully save the teeth to the twenty-fifth year the worst of the difficulty is over, except that in mouths where there has been great susceptibility we may look for occasional relapses even where a condition of comparative immunity has been established. The circumstances which bring about these relapses are not always apparent and it is sometimes difficult to account for them. Anything which changes the conditions of the mouth may do it, such as a pro- tracted illness, a change of climate which involves an entirely new environment, or any radical difference in the mode of life, or dis- turbance of the functional equilibrium of the individual. Severe men- tal stress is known to frequently induce an active recurrence of caries in a mouth which has for years been immune. But usually if a re- lapse comes it is easily controlled and not nearly so severe as the origi- nal attack. This reference to the original attack, the relapses, and the periods of immunity does not imply that there is a sharp line of demarcation between them. An occasional cavity, or cavities, may develop at any time, but there is a very great difference between this and the awful havoc which we see so often occurring during periods of great susceptibility. Neither does it follow, when we get a set of teeth in good condition after susceptibility, that there will be no further need of dental service, even though the mouth should remain immune. Where decay has once manifested itself extensively in a mouth the teeth should have the supervision of a dentist at regular intervals afterward. There is always the necessity for hygienic treatment in the way of removing deposits and general prophylaxis, besides the repairs so frequently required in the operations performed during susceptibility. In a delicate child during the growing period if the teeth decay rapidly it is not always possible to do permanent work, 128 DENTAL CARIES. and we may carry the teeth to the twentieth or even twenty-fifth year and have the formation of new cavities practically stopped, but with the necessity before us of making more permanent operations as the other ones fail from time to time. It is always best, of course, to make permanent operations in the beginning if this is possible, but it is not always possible with some of the temperamental conditions we meet in practice. To carry one of these young mouths through the susceptible period is often very trying but the result is well worth the effort. The plan of procedure should be about as follows: When a child is brought to the dentist with the teeth decaying rapidly there should be no half- hearted measures or perfunctory attention to the work. It is not merely a matter of filling cavities, though this of course should be done at once, and done as thoroughly as the circumstances will permit. But what is of equal consequence is that a campaign of prophylaxis be instituted with the definite aim of limiting the disease as far as possible in the future. The child should be schooled into a system of caring for the teeth by such an impressive lesson from the dentist that it cannot well go unheeded, and there should be a regular inspec- tion of the teeth by the practitioner to see that proper care is being given them, and that normal function is maintained. The key-note to the whole situation is the alteration of existing conditions in the mouth, and while — as has already been intimated — we do not know all we should about the conditions which influence this disease, yet we are certain of one thing that the establishment of full functional activity is favorable to the limitation of the disease. To this end all teeth should be kept comfortable for mastication, and wherever we find evidences that mastication is not being properly performed we should discover the cause and remedy it. A close observer can always tell whether or not the teeth and gums are subjected to the amount of friction necessary for perfect mastication by noting the unpolished surfaces of the teeth and the hypertrophied and congested condition of the gums, and where it seems impossible to establish the habit of good mastication in any given case, or in any particular region of a mouth, the child should be instructed to make up the deficiency by friction of the brush for a stated period of time each day. The time should be set by the dentist, and the patient urged to brush by the watch. The friction of the brush moistened in cold water over the teeth and gums for three consecutive minutes twice a day will soon have a very appreciable effect in stimulating the tissues to healthy action, and in polishing the enamel smooth and bright. DENTAL CARIES. 1 29 Cavities should be filled as fast as they occur, the aim being to keep caries out of the mouth at all hazards. Sometimes the disease is so rampant that it is difficult to maintain the courage of the patient, and yet such a case should be fought with all the energy and enthusiasm of the operator, to the end that he inspires the patient with the con- fidence of ultimate success. Such patients should be carefully schooled in the theory of an approaching immunity, and the operator who is in earnest in his management of the case may conscientiously promise this on the basis of what has been observed in a close clinical study of such cases. There is a reasonable expectancy that in ninety-nine cases out of one hundred the teeth can be saved if proper attention is given them, and the usual history is that even in a very susceptible mouth about the eighteenth or twentieth year the conditions begin to clear up and the hardest part of the contest is over. It is true that teeth are sometimes neglected so that when the dentist is finally consulted — usually as the result of pain — the conditions are so bad as to be very discouraging, and yet there is no case so hopeless where sufficient of the tooth is left as a basis for a filling, inlay or crown that the dentist should let it go by default. It is the lack of an enthusiastic application on the part of the dentist, a failure to show forth an evident confidence in the possibility of saving the natural teeth, and the neglect to sufficiently emphasize the importance of retaining them that has led many patients both in youth and middle life to become unappreciative of their real value, and indifferent as to their care. The dentist may not be able as has already been intimated with our present knowledge to treat the mouth medicinally so as to change a susceptible case to one of immunity, but he assuredly can by insti- tuting the proper line of prophylactic and operative procedures so influence the conditions as to at least control the disease and ultimately save the teeth. Not only this but he can by pursuing the proper course in the management of these cases so advance the period of immunity from generation to generation as eventually to limit the disease and bring it under easy control. It is frequently noted now that even where the deciduous teeth are extensively affected, if proper attention is given to the case the conditions are so changed that there is little tendency to decay of the permanent teeth, and they may be saved without much demand for filling. The future hope of the profession is in the study of conditions which exist in the mouth, and while the ability to properly perform operations is exceedingly important it is not more so than a close 9 I30 DENTAL CARIES. observation of the phenomena which influence disease and also which affect materially the outcome of our technical procedures. If we understand conditions we shall operate more skillfully, more intel- ligently, and the result of our work will redound to the greater credit of the profession and a more lasting benefit to those who place them- selves under our care. CHAPTER VII. EXAMINATION OF TEETH FOR THE DISCOVERY OF CARIOUS CAVITIES. BY GARRETT NEWKIRK, M.D. The practice of medicine in all of its departments may be com- prehended in two great divisions: First, diagnosis — finding out what is the matter; second, the choice and application of remedies. Physical exploration of the teeth for the discovery of caries might be styled mechanical diagnosis. It should be as carefully and thor- oughly made as an examination by the physician for the diagnosis of disease. While it is not all of dentistry to discover carious con- ditions, and prepare and fill cavities, these constitute the larger part of its employment. Every one who comes to the dentist for consultation and advice is entitled at once to a thorough examination of his teeth. He has a right to expect that no carious spot shall remain undiscovered. Every continuing patient should have such an examination at regular periods, and should be notified of the time if he fails to remember it. Examinations at stated periods are of the greatest importance with young people. They should be made in all cases at least twice each year; as a general rule once in three months; with some children, under special conditions, oftener. A systematic record should be made not only of conditions requiring operations soon, but of those which threaten danger at some future time. REGIONAL DIVISIONS FOR EXAMINATION. First. — Those pertaining to lines of union (so apt to be imperfect) between the enamel plates, on the occlusal surfaces of bicuspids and molars, the lingual aspect of upper incisors, and in the buccal or lingual grooves of molars. Second. — Gingival — regions bordering or beneath the gum tissue particularly those upon the labial and buccal surfaces from the central incisors to the last molars. Third. — Proximal — those surrounding and including the contact points of the teeth, particularly the surfaces immediately rootward from those points. 131 132 EXAMINATION OF TEETH FOR DISCOVERY OF CARIOUS CAVITIES. Fourth. — Marginal — along the lines of former operations, at the edges of fillings and crowns. SYSTEM AND METHOD. There should be a regular system of examination and a particu- lar method of marking diagrams. The writer has adopted the follow- ing rules. The lower teeth are examined first, with the patient in a position nearly erect, so that when the mouth is opened the light from the window falls directly upon the field of observation. Examination begins with the central incisor and proceeds to the last molar, first on the left, then on the right. For the examination of the upper arch the position of the patient is higher with the body and head inclined backward, so that as before the teeth meet the light fairly; and here the order of examination is the same. The diagram blank and a pencil should be on the bracket table, and a record made of each carious or suspected point immediately upon discovery. CONDITIONS FOR EXAMINATION. First, Cleanliness. — The first procedure for an examination of the teeth is to clean them. Not only must they be freed from calcareous deposits but as far as possible from stains. In no other way can every surface be brought to view and imperfections noted. The use of the scaler will often reveal points of sensitiveness or the hidden margin of a cavity. One should never pass an opinion as to the number and extent of cavities, or the probable cost of operations, till he has been permitted to put the teeth in a proper condition and make a recorded examination. Dryness. — Cleanliness of surfaces having been assured, the next precaution necessary is freedom from moisture. No accurate ex- amination can be made of a wet surface. The beginnings of decay are seen imperfectly or not at all through films of mucus and saliva. For an examination of the upper teeth so far as may be without the use of the dam, a cotton roll, or strip of lintine, or a thick piece of spunk is laid between the alveolar process and the lip or cheek, while the patient is requested to keep the mouth steadily open. Freedom from moisture for a corresponding examination of the lower teeth is not easily assured. The saliva ejector, valuable in all cases, • is here quite indispensable. If the operator has no assistant the patient himself may render service. A long roll of cotton or muslin is held down on each side of the alveolar ridge. For the left side, assuming the operator to be right handed, he will hold with the forefinger of his CONDITIONS FOR EXAMINATION. 1 33 left hand the roll between the tongue and the ridge, the assistant (or patient) holding the other firmly between the ridge and the lip. ' On the right side, per contra, the assistant will hold the roll against the lingual side of the alveolar ridge, the operator that next the cheek. After drying the teeth with spunk and warm air they are rubbed well with alcohol on cotton and dried again. Where secretions are specially viscid and hard to remove it is well to precede the alcohol with pumice. After this treatment the teeth present a different appearance. Pits and fissures are revealed in the occlusal, lingual and buccal surfaces; also shadows and color spots that often indicate proximal decay. Having obtained dry surfaces, the operator with a good eye, sharp exploring instrument and a magnifying mirror, will be able to discover carious spots of all classes save one; but that one is perhaps the most insidious and dangerous of all — the decay which has its beginning close to and directly rootward from the contact point of a tooth. These are the decays that sometimes penetrate deeply with an open- ing so small as to be hardly discoverable by the finest point of an instrument. Unseen and unsuspected, their ravages proceed till a large extent of dentin is disorganized, and the enamel of the occlusal surface is so undermined that it breaks down suddenly under stress. These are the cavities that patients will tell us, "Came all at once," because so long as the enamel stood over the chasm there was nothing to indicate its presence. A common practice is that of depending on the evidence of thread, passed between the teeth; but this alone is not conclusive. By the roughening or tearing of floss silk it is true that we suspect decay, though the rough edge of a filling, or tartar, may produce the same efifect. But the free passage of floss is not conclusive evidence of a healthy condition. The surface of the tooth may seem perfectly smooth to the thread over a spot of unbroken, dead enamel and a sepulcher of dentin. In other words the thread will show us plainly very often where decay is, but is unreliable for determining where decay is not. The only conclusive method is to get separation for vision and instrumental exploration. Where the slightest doubt exists as to the integrity of teeth at these points, the rubber dam should be used in association with the mechanical separator. With the dam in position we are certain of dryness, and there is no call for haste in the examina- tion. From four to six teeth may be included at once, and their proximal surfaces examined in succession. By the use of the mechanical separator, sufficient space may be 134 EXAMINATION OF TEETH FOR DISCOVERY OF CARIOUS CAVITIES. obtained nearly always in a few moments for a decisive exploration. A bit of space with a gleam of light makes a world of difference in the field of observation. Where before no sign of decay was seen, it may be that a speck of discoloration, brown or whitish will appear. A delicate steel point finds an opening, a sharp, thin chisel breaks the enamel roof, and the excavator possibly reveals a deep extension of decay. A condition such as this we have no right to overlook. We should know positively, either that it does or does not exist. We have no right to dismiss an examination with the word or thought, "I guess that's all right." It is our business to know. Opinions fathered by wishes have no value. RECORDS OF EXAMINATION. The dentist should keep himself supplied with pads of examination blanks such as are kept in stock by the supply houses. Each blank should exhibit a diagram of the teeth, both deciduous and permanent, with lines for name and date. In some cases it is well to make the first record tentative — pre- sumably incomplete. Pursuing the methods first described, the teeth are surveyed as thoroughly as may be without the employment of dam and separator. The diagram is marked for every cavity and fissure that is positively indicated, and at every proximal line where the least uncertainty exists an interrogation point ( ?) is placed. After other operations have been concluded, the doubtful spaces are examined one by one with the aid of dam and separator. If there is found in one place nothing to do, well. If in another but superficial decay, it is polished and medicated with reference to the adage, "A stitch in time saves nine." If a cavity is discovered, separation is increased and a filling, temporary or permanent, introduced. When all this is done the operator may truly feel that no interest in the case consigned to his care has been neglected. CONCLUDING NOTES. Special care should be taken to examine along the subgingival margins of gold crowns, especially those placed over teeth with living pulps, where the right preparation could not have been made and there was necessarily an ill fitting band. Also careful exploration should be made about the margins of Logan and other bandless crowns for caries that may have begun in the root. For a complete, visual examination of cavities beneath the gingival gum, a thin bladed retrac- CONCLUDING NOTES. I35 tor is convenient, and often it is necessary to control hemorrhage with carbolic or trichloracetic acid or adrenalin chloride. Failure to examine for decay beneath fillings of unfavorable ap- pearance is a common fault and followed often by serious consequences. The dentist is apt to take too much for granted as to conditions beneath fillings made of all sorts of mixtures that have gone under the general name of amalgam. We should not be prevented by a false conserva- tism from thorough examination in these cases. We should make doubly sure that our insidious enemy, caries, does not "steal a march" on us in the tattered uniform of a friend. A small keen hoe or hatchet excavator will oftentimes penetrate a dead enamel wall and reveal a cavity better than a delicate pointed explorer. No service rendered by the dentist should entitle him to better compensation on the basis of time than that involved in a careful examination of the teeth. CHAPTER VIII. SEPARATION OF TEETH PREPARATORY TO OPERATING ON CAVITIES IN THE PROX- IMAL SURFACES. BY GARRETT NEWKIRK, M. D. Restoration is the watchword of operative dentistry. Simply upon the forms of the teeth depend their relations one to another and to their surrounding tissues, and together with color, their appeal to the esthetic sense. Among the many considerations necessary in the restoration of tooth forms, and one of the most important, is that of the interproximal space. This has a definite relation to the forms and contact points of the teeth involved. For the first adequate study and presentation of this subject the profession is indebted to Dr. G. V. Black, through a paper read by him before the Odontographic Society of Chicago, and published in the Dental Review, 1890. Up to this time and for many years previous the best operators had often advocated the restoration of the natural forms of teeth as a matter of idealism, but none had grasped the subject in all its relations. Dr. Black set forth the importance of a normal interproximal space for the conser- vation of healthy gum tissue, to secure the best conditions of cleanliness, to prevent the lodgment and impaction of food, to allow the ready cleansing of the adjacent surfaces, to insure in large measure the permanence of fillings, to promote the comfort of the patient and satisfaction of the operator — all this depending of necessity on the true proximal contour of the teeth, in accordance with nature's plan. Separation for dental operations, by whatever method, has for its object the assistance of the operator in the restoration of tooth forms, and the preservation therewith of healthy interproximal gum tissue. Without separation preparatory to filling, it is impossible to secure the necessary contours. Separation may be of two sorts, first, by the slow pressure of some expansive material like wood, cotton, linen tape, rubber or gutta- percha, continued for hours or days, and denominated "previous;" second, by a driven wedge or one of the mechanical appliances, coin- cident with the operation of filling and styled the "immediate." 137 138 SEPARATION OF TEETH. Both 'methods are valuable and necessary, each in its place. As a rule the previous should be followed by the immediate, for whatever space has been obtained beforehand should also be held during the several stages of operative procedure. PREVIOUS— SLOW WEDGING. The writer will say at the outset that the longer he continues in practice the less he depends on very slow wedging for the separation of teeth. He is more fearful than formerly of inflicting permanent injury to the tissues involved — viz., the pericemental membranes, the interproximal alveolar wall, and the over-lying gums. All these tissues will endure a certain amount of pressure with temporary dis- placement, and return to their normal positions unharmed when the pressure is removed; but the pressure should not be greater nor longer continued than is absolutely necessary to the restoration required. It involves primarily the question of blood supply — a diminution here and an increase there within the various parts involved. This may be illustrated by any one in a moment. Place the ends of your thumbs together so that the free margins of the nails overlap. Press these one upon the other alternately and repeatedly, and watch the blood pressure as it changes beneath each nail, the red and the white coming and going, one congested, the other anemic. This is precisely what takes place in the tissues surrounding the root of a tooth when pressure is brought to bear for separation. Ere long if pressure is not relaxed absorption begins. It follows, therefore, that whenever the "im- mediate" method of separation can be employed judiciously, it is the one to be preferred. GUTTA-PERCHA. Slight, non-irritating separation may be made to great advantage in many cases with gutta-percha, this being used at the same time as a temporary stopping. As we know, it is often advisable, sometimes unavoidable, that such fillings should be inserted for a period of days or weeks. In these cases it is possible to make the material accomplish the double purpose of protection and separation. By the use of considerable force with a broadfaced burnisher as the material slowly hardens in the cavity, it may be so compressed as to make it elastic — like rubber, only in smaller measure. The effect will be increased if the gutta- percha is inserted while the teeth are held slightly apart by the me- chanical separator, which should be kept in place till the filling is cold. Then, the gutta-percha answers well if it simply holds the space COTTON. 1 39 obtained by the separator till the next sitting, when by re-application of the instrument the space may be increased, probably to the full extent necessary. Gutta-percha is further useful as a separating material in that the gum tissue that sometimes overlaps the gingival margin of a cavity may be crowded back from the enamel edge — or from the cemental border of an extruded tooth — making possible a clearer view of the parts, and better preparation for the filling. But this must be done with extreme care, otherwise serious injury may be inflicted by over-pressure. Years ago it was advised by some to leave the fillings much over-full, in order that the material might be forced down and spread by the cusps of the occluding teeth, allowing it to remain for weeks or months. In some instances the effects of this practice were disastrous. The interproximal gum tissue was injured or destroyed, and articulation of the teeth seriously interfered with. Whenever it is purposed to use a temporary stopping for separa- tion, all over-hanging walls should be vigorously chiseled away and decayed matter removed from the cavity, both for medical treatment and to give a firm base for the pressure to be exerted. And, as a rule, it pays in satisfaction and efficiency to use the rubber dam. In this connection it seems best to quote a paragraph from Dr. C. N. Johnson's work on the Principles and Practice of Filling Teeth: "To economize time in the management of these cases, it is well for the operator, on examining a mouth where several fillings are needed, to select these proximal cases at the first sitting and pack gutta-percha in each of them. He may then proceed with other work, and by the time that is completed some of the teeth thus wedged will be found ready to operate upon. The more stubborn cases may be left till the last, and, if necessary, the gutta-percha may be renewed in these as the other operations are in progress." In speaking of this material it should be understood that the writer has in mind not merely that known as "sheet" or "base-plate," but the various kinds of prepared gutta-percha sold by the dealers in convenient form for use. They are easily worked but inferior to the old-fashioned sort in resistance to wear, and not so elastic. The gray gutta-percha is preferable to the pink only for its appearance in conspicuous places. COTTON. Among the first of materials used for separating teeth was cotton, in the form of compressed pellets, pressure depending on the absorp- 140 SEPARATION OF TEETH. tion of moisture; and it is still used by some almost exclusively. As a separator merely it is more effective than gutta-percha, and may be preferred whenever a considerable space is demanded within a limited time. As a rule it produces no great soreness, and if the teeth are held steady by the mechanical separator during the subsequent opera- tion, ordinary, careful malleting is well borne by the patient. But the cotton pellet is, of course, unfit for a temporary stopping and should not be used for more than a day without change. If saturated first with sandarac varnish as it sometimes is, making it quite impervious to moisture, it is no better than gutta-percha for separating, and by no means so good a filling. Cotton is particularly valuable for making space between the incisors, or between a cuspid and a lateral incisor. As a rule the pellet should be introduced from the lingual direction, and, with a thin- bladed instrument pressed toward the incisal borders of the teeth. It is readily seen that by crowding the material from the base toward the apex of the interproximal triangle we secure the advantage of two inclined planes along the teeth. Now, if first a piece of waxed thread shall have been introduced rootward, it may be drawn down upon the pellet, the ends carried through incisally and tied firmly so as to give additional compact to the material. Also the ligature prevents crowding out of the cotton toward the tongue or the lip, and the whole force of expansion will be directed against the teeth. As a form of cotton for this and many other purposes the writer is partial to "lin- tine" or "cottonoid," as bought in sheets. RUBBER. An easy method of separating — easy for the operator — is that of stretching and drawing between the teeth a piece of rubber, that may be cut from a good sized elastic band, or from strips of different thick- nesses and widths supplied by the dealers. But these if kept long on hand deteriorate in quality and become worthless. In a small proportion of cases, with phlegmatic patients, where teeth have short crowns with long roots and are very hard to move, one may be justified in using a piece of rubber, narrow and not too thick — to get a "start" for the space required. Then, if the mechanical separa- tor is insufficient, some other material should be used to induce further separation gradually. Nearly always, if the elastic quality of rubber is depended on entirely for a considerable movement of the teeth, much annoyance or real suffering will be experienced by the patient, not only through WOOD. 141 the period of wedging, but during the operations to follow. While not easy to account for, it is a fact of experience, that the pressure of elastic rubber between the teeth gets "on the nerves" of a great many people as nothing else will. One risk of using the rubber is that of injury to the gum tissue. As the material contracts labio- lingually it bulges into the interproximal space toward the gum, and indeed is likely to slip upon the surfaces of the teeth in that direction. WOOD. The wooden wedge for separating teeth has been much employed. Of the many woods recommended at various times all have been quite discarded except the orange wood, which is supplied in neat bundles by the supply houses. Where one suspects the presence of a small proximal cavity in a very close space, in the mouth of a sensitive person, where the insertion of cotton or gutta-percha would be difl&cult or ineffective and rubber inadmissible, where allowable force with the mechanical separator moves the teeth but slightly and an increase of space must be had by the slower process, then, in the slight space gained by screw force, we may insert a thin wedge of wood, by hand pressure merely or with one or two light taps of the mallet. The wedge may then be separated from the stick with cutting pliers made for the purpose. If, however, before its insertion a sharp notch is cut well around at the base of the wedge, it will afterward break off readily from the body of the stick, and, as a rule, with less jar than that from the pliers. On removal of the separator the wedge is left snug in place, where by slow swelling under moisture it separates the teeth. TAPE. Some practitioners have been partial to waxed linen tape of various widths, for slow separation. The unrolled tape is dropped into hot beeswax, let cool, and is then stripped of adherent wax. With slow, persistent pressure, this thin tape may be crowded between the teeth, and usually without the aid of a mechanical separator. Otherwise, in place of the screw separator one may use a thin, narrow steel wedge, at the end of a strong handle, that the operator may if he chooses make for himself. This can be inserted near the necks of the teeth, and by hand pressure alone will induce sufficient space between the crowns for the insertion of tape or thin wood. The ends of the tape may be cut close with a very sharp knife or fine pointed scissors. The best scissors that I have found for this purpose, and that I keep 142 SEPARATION OF TEETH. on the bracket for general use, is a small "manicure" pair with the extreme sharp point of each blade ground away. Another method of preparing the tape is to dip it in a thin solution of gutta-percha in chloroform, and then let the chloroform evaporate. This leaves the tape permeated with a film of gutta-percha, which makes it very tough and impervious. It will therefore not deteriorate in the fluids of the mouth as rapidly as waxed tape. It is well to remember that wherever slow wedging is necessary, the chief difficulty is overcome when the first slight space has been secured for a day. THE MECHANICAL SEPARATOR. It is axiomatic in the mechanical world that, wherever a certain thing is to be done in a particular way, a specific machine accurately made, and intelligently directed, will secure results more uniform and definite than are possible by the varying, individual hand method. Operative dentistry consists largely of a series of mechanical problems, and, wherever conditions admit, the principle above stated holds good. To a celebrated business man has been accredited the statement that he never would do any sort of work himself that he could hire done as well or better by some one else. We may say in like manner of any mechanical operator that as a rule he cannot afford to do by direct effort that which may be better done by an intermediate mechanical contrivance. As a recent example of this principle we have the anatomical articulator, which eliminates much of experiment and guess work in the proper arrangement of artificial teeth. The separation of teeth as considered within the scope of this chapter is a mechanical process, and we wish to know how far it may be accomplished by the application of screw and wedge forces, in a manner positive and definite. What are the requirements of such an appliance, and have they been successfully met? First: The points of pressure must be aside and far away from the median line of the proximal surface; otherwise they will intrude upon the field of operation, or, if carried too far rootward will press dangerously on the interproximal gum tissue. Second: The pressure having to be well aside from the median line, it should be upon both sides equally. Third: As the separating applies to both teeth, there should be necessarily four distinct points of pressure at regular distances. Fourth: The points must be far enough over the crown so that THE MECHANICAL SEPARATOR. 143 1; Fig. 106. — Perry Separators. 144 SEPARATION OF TEETH. their tenaency under pressure will be to move rootward, otherwise they would be likely to slip off; but they must at the same time be stayed, to prevent their going too far, with impingement on, and danger of injury to, the soft tissues. Fifth: The four points make necessary two bars, each with a right and left hand screw, through which forces may be exerted alike in both directions. Sixth: While the principle of the instrument is everywhere the same, proportions of the parts must vary for purposes of adaptation to the different forms and classes of teeth, considered in relation with their interproximal spaces. This fact precludes the construction of any so-called "universal" separator which shall be equal to the different forms, each in its special field. Either the "universal" will fail to meet all these requirements — for example, having points on one side only with an opposing wedge; or, it will be intricate and cumbersome, lacking the simplicity of the special instrument. Just as possible a universal saw for the carpenter, or a universal pattern for a coat, as of one separator adapted to all parts of the mouth. It is altogether probable that the one who owns a " set ' of sepa- rators will employ one form or another much oftener, and with greater satisfaction in every case, than the possessor of a "universal" only. "The best is none too good," as relates to the instruments of operative dentistry. When one is selecting an appliance that ought to last throughout his professional life, he can ill afford to ignore this truth. It is here that the mistake of a moment is oft the detriment of years. THE BEST SEPARATOR. The author has no hesitation in saying that the principles of mechanical separation have found their best expression in the "set" invented by Dr. S. G. Perry, originally four in number, now six. These various forms are marvels of ingenuity, adaptation and sim- plicity. Artistic of construction yet strong, there is slight chance of their being superseded. The usual objection offered to the Perry set is that it is expensive; but, if we take into consideration both usefulness and durability, in the long run it will prove the best investment. Few dentists would think of going into practice without a good chair or first class engine; and yet, one might perform good operations over a plain arm chair with a head-rest. The writer is positive that he would rather use a cheap chair till he could make enough money to buy a good one, than to practice one month without the Perry separators. THE BEST SEPARATOR. 145 Let US enumerate, briefly, some of the advantages and uses of mechanical separation. First : In Examination of Teeth for Carious Cavities. The important office performed by the separator in this connection has been considered in Chapter VII. Second: Preparatory to Slower Wedging and Temporary Stoppings. Where it is evident that sufficient space cannot be had with the mechanical separator alone, it may be used to obtain room for the insertion of cotton, wood or gutta-percha; and in like manner for the introduction of gutta-percha as a provisional stopping. Third : In the Preparation of Cavities for Filling. Time and observation demonstrate to every experienced operator that faulty preparation is probably the commonest fault of dentistry. Back of this fault very often lies the fact of insufficient space— teeth that have had no separation; or having been separated have nothing to keep them apart for operations following: — For what sufficeth it to wedge with cotton or wood, and make no provision for holding the space obtained? The mechanical separator will do this; and it will hold the teeth steady, so that the instrument employed, chisel, excavator or bur, can be used more accurately, and with less pain or shock to the patient. And the separator with four points generally is not in the way of observation, does not obtrude in the interproximal space, and holds the dam aside for the admission of light. It is well to remember, however, that occasionally where wide lateral extension of a cavity is demanded, either for "prevention" or on account of existing decay, a point of the separator may impinge upon the field of operation. In such a case the instru- ment may be used for preparation of the main cavity and then removed. Before removal, however, if sufficient space exists for the insertion of a narrow wooden wedge, this may be employed to hold the space, both for the final preparation and the beginning of the filling. Fourth: For the Insertion of Gold Fillings. As in cavity preparation, the separator holds the teeth steadily in position for instrumental service in filling. It makes the use of the plugger more accurate and positive, and the application of mallet force less trying to the patient. As a rule where a tooth is filled after "immediate" separation by one of the Perry instruments, with or without slight wedging before- 146 SEPARATION OF TEETH. hand, the patient will not complain of any malleting necessary for the proper condensation of gold. Fifth: In Connection with Porcelain Inlays. The mechanical separator may assist greatly in securing access for cavity cutting and grinding, facilitates the removal of a matrix, or the insertion of an inlay, holds the teeth apart for the final finish of the work, especially in connection with the anterior teeth and cavities of moderate extension. It may also be used to gain space for the removal of inlays that have become loosened, and their re- insertion. Sixth : Preparatory to Filling with Amalgam or Cement. The separator gives the advantages before described for preparation and initial space. The teeth are held apart and steady up to the moment of applying the matrix, or with the use of a hand matrix the separator may remain in position. Seventh : For the Finishing of all Proximal Fillings. . To give access for fine cutting instruments, finishing files, tape or disks, for proper "knuckling," there is nothing to compare with the Perry separators. In Miscellaneous Conditions Requiring Separation. Cases are presented where the interproximal space has been left unprotected, where the patient is distressed by food impaction with every attempt at mastication and the gums perhaps are continually congested and sore, in consequence of previous faulty operations. Such teeth are seldom firm in their sockets, and in many cases may be separated by the "immediate" method sufiiciently for contour restora- tions. Not infrequently we find some foreign substance, a piece of wooden tooth-pick or berry seed perhaps, imbedded between the necks of teeth and hard to dislodge, or, as occurred recently in the writer's practice, one may discover a sequestrum of bone as the result of arsenical poisoning. In such cases the Perry instrument with its widely separable points will render valuable aid. Final Considerations. — To adjust the mechanical separator easily and deftly requires practice, and the operator must not expect smooth sailing in every case at first. With the bicuspid and molar forms, the lip of the patient is likely to be lifted up uncomfortably. To relieve this at once a smooth steel instrument like the handle of an explorer should be inserted at the angle of the mouth and passed gently forward, lifting the lip over. Whenever the separating points are going higher than they should, so as to crowd upon the gums, the screws should be relaxed and the THE BEST SEPARATOR. 1 47 instrument held in proper position while gutta-percha is warmed and crowded under the bows. When this is hard (and cooling may be hastened with the chip-blower), the rootward movement of the points is prevented and separation may proceed. The screws should be kept well oiled, both for ease of working and to prevent their wearing out. They should be turned on beforehand till the points are at the distance apart that will just allow them to slip over the teeth. Then with but a little turning the instrument finds its true position, and the wrench has less to do within the mouth. It is said that some are deterred from using the molar separator by what they consider the extreme difficulty of its application in con- nection with the rubber dam, for in most cases the clamp must be dispensed with. It is not hard to obviate this difficulty. Apply the dam as usual and the clamp temporarily. Then ligate, if nec- essary drawing knots of thread from both sides into the furthest inter- proximal space. After exchanging the clamp for the separator the rubber will rarely become displaced. The writer has discovered that in certain unusual cases some forms of the separators may be used in a manner not show^n by the ^^ Directions. ^^ For example, one may find molars so small that the bicuspid form would apply — or a first molar so much larger than the second, or a second so much larger than the third, that the bicuspid- molar separator reversed — i. e., with the larger bow forward, will best meet the requirement. Force should be applied always with immediate reference to the feeling of the patient — at first barely to the point where he admits that the pressure is uncomfortable — if really painful the screw should be turned back a little. One may say to the patient truthfully that in a few moments the feeling of undue pressure will pass off. After- ward as a rule there will be no objection on his part to quarter or half turns of the screws with intervals of rest between. Tact and caution on the part of the operator must never relax. The temptation to hurry and crowd must be resisted. Here, as in relation with other operative procedures, patients have their idiosyncrasies. One will disclaim any sense of discom- fort whatever, one will anticipate trouble that does not come, while another is truly hyper-sensitive and deserving of the most delicate consideration. Now and then, once a year possibly, a patient will present with whom the separator is impracticable by reason of unusual tenderness of the peridental tissues or general nervous timidity. Much depends on the attitude of the operator in the first intro- 148 SEPARATION OF TEETH. duction of any appliance that might excite the fears of his patient. If we show to the patient, older or younger, the necessity of space and the advantages of separation; if we assure him that we shall be careful not to carry the pressure beyond the point of reasonable en- durance on his part; if we are painstaking further to consult with him or her as to the degree of force that may be easily borne, we shall have little trouble in the use of this most valuable assistant. CHAPTER IX. EXCLUSION OF MOISTURE FROM THE TEETH DURING OPERATIONS. BY GEORGE EDWIN HUNT, M. D., D. D. S. GENERAL CONSIDERATIONS. The desirability of excluding the saliva from tooth cavities about to be the scene of operative procedures is based on four considerations. First, perfect dryness is essential to secure cohesion of gold. Second, the saliva is laden with micro-organisms, many of which in their life processes form by-products detrimental to tooth structure, and, there- fore, exclusion of the saliva is necessary that the tooth structure may he sterilized. Third, saliva obscures and distorts the view of the walls and angles and dryness is desirable that a perfect view of the cavity may be obtained. Fourth, the dentin of teeth with living pulps is much more sensitive when wet and dryness is necessary to diminish the pain of excavating. Before Dr. Sanford C. Barnum, of New York City, invented the rubber dam and gave it to the profession in 1864, dryness of tooth structure was obtained by the use of napkins, cotton and other absorb- ents. The exclusion of saliva by such means was necessarily of com- paratively short duration and extensive operations with cohesive gold were impossible, although the more skillful practitioners in those days acquired a degree of dexterity in handling napkins and absorbents that is seldom seen among our contemporaries. Since 1864 nothing has been found to equal rubber dam for excluding the saliva during lengthy or intricate operations, although absorbents may be used in many- short operations with perfect success if they are used intelligently. It is therefore necessary that the operator become skilled in the ad- justment of the rubber dam, to the end that it may be used to the best advantage and with a minimum amount of annoyance and discomfort to the patient, to whom, under the most favorable circumstances, it is a trial. Many operators do not use the rubber dam as often as they should. This is usually due to the fact that the operator is unskill- ful in adjusting it and dreads the time and trouble his unskillfulness requires to place it in position. In this, as in all other manual opera- tions, practice alone will bring ease of manipulation. 149 150 EXCLUSION OF MOISTURE FROM TEETH DURING OPERATIONS. THE USE OF RUBBER DAM. Rubber dam is classified as heavy, medium and light in weight, according to its thickness. Heavy and light dams each have their advantages and disadvantages. Heavy dams are less likely to be torn in adjustment, they will more often remain in place without the use of ligatures or clamps, and they are not easily caught up by revolving burs, stones, discs or other engine instruments. Light-weight dams are more apt to be torn in adjusting, usually require ligatures or clamps to hold them in place, and are readily caught up by engine instruments by which they may be torn or cut. However, owing to the conforma- tion of the teeth, or their relation to each other, it is often difficult to adjust a heavy dam where a light one can be carried to place with com- parative ease. Therefore, if but one weight of dam is to be used, a medium weight, which diminishes the disadvantages of the two ex- tremes, is best. A light colored dam is preferable as absorbing less and reflecting more, light. Rubber dam, like all rubber, deteriorates with age and is sometimes ruined by the manufacturer in vulcanizing. A simple test for quality is to stretch it well with a thumb or finger and note whether it returns to its original shape without bagging or tearing. Size and Shape. — For operations on the anterior six teeth a trian- gular shaped piece of dam will be found both efficient and economical. This may be obtained by cutting diagonally a piece from six to nine inches square, the long side to be against the upper lip when adjusted. For the posterior teeth a piece from seven to nine inches square will be found most useful. It is poor economy to use smaller pieces as the edges will be found to be in the way and imperfect exclusion of saliva from the exposed surface of the dam may result. The Holes. — Holes permitting the passage of the tooth crowns may be made in different ways. Various sized single punches may be obtained from hardware or dental supply dealers or a triangular punch, capable of making three different sizes of holes, may be used. With these, the dam is placed on a block of wood and a hammer or mallet used on the punch. Very few operators now employ this method, however. The most efficient method is by the use of one of the improved rubber dam punches on the market, having a revolving steel disk with four or more round holes, varying from f of a milli- meter to *3 millimeters in diameter, which engage a pivoted cone- shaped steel plunger, punching the desired sized hole in the dam. If a punch is not available, the rubber may be tightly stretched over the tapering round handle of a gold plugger, when the application of a sharp knife blade to the tense rubber on the side of the handle will THE USE OF RUBBER DAM. 151 result in a clean cut, round hole. The size of the hole may be varied by nicking the rubber at a greater or less distance from the plugger end and a little experience will enable the operator to thus cut holes of any desired size. As a rule operators are more apt to use holes too small rather than too large. The distance between the holes will vary in different cases, from 2 to 4 millimeters being the usual distance in medium weight rubber. The lighter the rubber the further apart the holes should be. In abnormal cases, where the teeth are separated or the gum tissue has receded, the holes may have to be much further apart. In normal cases, teeth with long crowns and pre- senting large interproximal spaces, require that the strait of rubber between the holes be wider than in cases where the crowns are short and the inter- proximal space small. These matters should be noted, for if the distance between the holes is greater than necessary, the rubber will bag in the inter- proximal space and be in the way, and if it is less than it should be the strait of rubber will slide down between the interproximal gum tissue and the proximal surface of one of the two teeth, exposing the gum tissue and causing a leak. This latter will also occur if the holes punched are too small, requiring excessive stretching of the rubber to encircle the neck of the tooth. Fig. 107. — Rubber Dam Punch. 152 EXCLUSION OF MOISTURE FROM TEETH DURING OPERATIONS. The location 0} the holes will be governed by the location of the tooth to be operated upon. In all cases the holes must be far enough from the upper edge of the dam to permit the rubber to cover the upper lip after adjustment. If the patient has a moustache, the holes must be far enough from the upper edge of the rubber for the latter to cover the moustache. But in no case should the rubber cover the nostrils or interfere with breathing through them. For teeth on the right or left of the median line a corresponding variation to the right or left of the median line of the dam is desirable and, in a general way, the curve of the holes should correspond to the curve of the dental arch. The novice should hold the rubber dam against the teeth to be isolated and note the approximate location of the holes necessary to have the dam cover both lips properly after adjustment. The number of teeth isolated by the dam is a matter of importance. In those abnormal cases where the rubber is adjusted with great difficulty, owing to the shape of the teeth, wear on the occlusal sur- faces, unusual resistive power of the facial muscles or other cause, and in treatment cases where the operation is short and easy of execution, the number of teeth isolated may be much reduced, sometimes even limited to the one tooth to be operated upon, but in nearly all cases several teeth should be included. This is desirable in that it gives better light and better access by getting the rubber out of the way and diminishes the danger of catching up the rubber in revolving engine instruments. The opportunity for error in operative procedures is sufficiently large without adding to it inconveniences within the control of the operator, yet many operators make the mistake of including too few teeth when adjusting the dam. In all distal surface operations the tooth lying distally should be included. In operations on the anterior teeth, for convenience sake, from four to six teeth should be isolated. In operations on the molars and bicuspids the teeth anterior should also be isolated up to and including either the lateral or central incisor. On account of its anatomy the cuspid is an unsafe tooth at which to stop. It has less of a constriction at the neck than any of the other teeth and the dam, whether ligated or not, is more likely to be worked crownwards by the action of the tongue and lips than with other teeth. For this reason, in operations on the lateral incisors the rubber should include the first bicuspid on that side and in operations on the bicuspids and molars should extend forward to one of the incisors. Adjusting the Dam. — Prior to adjusting the dam, if the cavity reaches the occlusal surface or incisal edge, the operator should care- fully note the articulation and the landmarks of mastication as a guide THE USE OF RUBBER DAM. 1 53 for the fullness of his filling. If the teeth set very closely together and especially if the occlusal surfaces and incisal edges are badly worn, as in an "end to end" bite with the "ball and socket" tempero- mandibu- lar articulation, a waxed thread should be passed between the teeth about to be isolated and all calculus and rough or sharp edges of fillings or cavities revealed by the fraying of the thread, removed and smoothed so the dam will not be torn. Dr. C. N. Johnson suggests that a thin broad instrument like a gum depressor or thin spatula, forced between the teeth and carried rootwards by a see-sawing motion, will smooth rough or jagged edges of enamel left by caries and permit the safe passage of the dam. A rubber or wooden wedge will also move the teeth in a few moments sufficiently to permit the passage of the rubber at any particularly difficult point. Just before proceeding to adjust the rubber the tooth crowns should be swabbed with a pledget of cotton dipped in absolute alcohol, to remove inspissated mucus, food debris or other infectious matter which might be crowded under the free margin of the gum in adjusting the dam. On the anterior teeth and also on the posterior teeth when it is not intended that a clamp be used, the dam should be adjusted first over the tooth nearest the operator, taking the others in succession. By this method the best view of the field of work is obtained. The dam should be stretched labially or buccally and lingually by the thumb and fingers of the right and left hands and worked rootwards by a see- saw motion until the rubber is well down to the cervix and the strait between the holes is pressing down on the interproximal gum tissue. In performing this operation on the anterior lower teeth the operator stands at the right and si ghtly in front of the patient, the fingers of his right hand guiding the rubber on the labial aspect of the teeth, his left hand fingers within the oral cavity guiding the rubber on the lingual aspect. In adjusting the dam on the anterior upper teeth the position of the hands is reversed, the fingers of the left hand caring for the labial and those of the right piloting the lingual portions of the rubber. The position of the hands will be naturally suggested by the convenience of the operator in adjusting the dam on the posterior teeth, the right hand guiding the buccal and the left the lingual portions of the dam while operating on the left side of the mouth and the positions being reversed on the right side of the mouth. As a rule simply hanging the rubber on the teeth as described is all that is necessary at this time to keep it in position but if there is a decided tendency for it to slip oflf or to be thrown off by the action of the tongue and lips, a piece of waxed floss silk thread should be passed down the distal surfaces of the end 154 EXCLUSION OF MOISTURE FROM TEETH DURING OPERATIONS. teeth beyond the point of contact. This will hold the rubber in place temporarily. In difficult cases, where the teeth are closely in contact and have broad contact surfaces, or perhaps facets worn on the proximal sur- faces, a little vaseline on the rubber between the holes will facilitate its passage between the teeth. Sometimes the use of a waxed silk thread by an assistant or by the operator is necessary to carry the strait of rubber rootward past the point of contact. In some cases the pas- sage of the rubber can be accomplished by stretching it well and tilting it so the edge of the rubber strait presents at the point of contact in- stead of the width. If the rubber is securely hung over the first tooth or teeth and an especially difficult point is reached, it may be passed, care being used not to confuse the holes and tooth crowns, and the rubber adjusted over the remainder of the teeth, the operator finally returning to the refractory one. Occasionally difficulty will be experienced on account of involuntary movements of the cheek, lip and tongue mus- cles. Dr. C. N. Johnson recommends that the patient be given a hand mirror with which to view the operator's efforts. The patient's at- tention thus being directed to the difficulty, the muscles will usually be voluntarily relaxed. In obstinate cases, if this method does not succeed, the application of the dam should be limited to as few teeth as possible. Having hung the rubber on the teeth temporarily the lower edge of the dam should be raised and a napkin placed in position over the lower lip so the dam will not come in contact with the lip or with the chin or cheeks, and napkin and dam secured by the rubber dam holder. A saliva-wet dam is a great source of discomfort and annoyance to the patient if in contact with the skin. The patient being fairly comfort- able and the lateral edges of the dam held back out of the way, the operator is free to return to the adjustment of the rubber to the teeth. To insure a saliva-tight joint the edge of the rubber must be turned rootward so it will pass between the tooth and the free margin of the gum. This can often be accomplished by simply stretching the dam labially and lingually and working it well rootwards before releasing it. Sometimes a flat instrument, like a spatula, run around the cervix, will turn the dam margin rootwards. Ligating the tooth will always accomplish this result. Ligating the Teeth. — Ligatures and clamps should only be used when they are necessary to the success of the operation, but they are often necessary. If the carious cavity is a proximal one, the tooth should be ligated to insure security of the dam. For the same reason it THE USE OF RUBBER DAM. 1 55 is well to ligate the tooth facing the cavity. Often the end teeth of those isolated will need ligating in order that the action of the tongue, cheeks, and lips may not force the rubber crown-wise. On molars and bicus- pids, the clamp, as will be explained later, takes the place of a ligature on the tooth to which it is applied. In operations on incisal edges or occlusal surfaces, or in treatment cases it is often unnecessary to use ligatures at all. The ligature should be a well waxed floss silk thread made for the pur- pose. If the interproximal space is large enough to permit of it, the liga- ture may be passed from labial or buccal to lingual between the point of contact and the interproximal gum tissue and returned in the same manner. Usually it is better to force it down between the approxi- mating surfaces past the point of contact. Having passed it rootward down the mesial and distal surfaces of the tooth to be ligated, the ends should be gathered up and the portion embracing the proximal and lingual surfaces of the tooth carried rootward by traction, the rubber preceding the ligature. This will curl the rubber edge rootwards, as Fig. 108. — Surgeon's Knot. desired. Often this is all that is necessary for the retention of the rubber and the floss silk may be removed, or, in cases where the inter- proximal space is small and the point of contact well rootwards, the ends of the thread may be cut off close to the labial surface of the tooth and will retain the rubber in position by its wedging action. If com- plete ligation is desirable, the first part of a surgeon's knot (see Figure 108) should be tied and, just before it is drawn taut, traction again made rootward, supplementing this, if necessary, by carrying the thread rootward with a suitably shaped blunt instrument, as a plugger, used on the lingual surface. Having carried rubber and thread fully to the cervical constriction, the knot should be tightened and the tie com- pleted. The free thread ends may now be cut off close to the knot with curved bladed scissors or, if an end tooth, a dam weight may be fastened to the ends of the thread and the weight passed back and left suspended over the patient's shoulder. This latter method assists in 156 EXCLUSION OF MOISTURE FROM TEETH DURING OPERATIONS, keeping the rubber out of the way of the operator. The remaining teeth should now be ligated in rotation, as above described. Dr. E. K. Wedelstaedt suggests an effective method of ligating. The first portion of the surgeon's knot is made on the lingual surface instead of the labial or buccal, and the thread ends again passed through the interproximal spaces to the labial or buccal. Strong traction is now made on the thread ends and the half completed knot on the lingual carried rootwards to the cervical constriction, with a suitably shaped blunt instrument. A full surgeon's knot is now tied on the labial or buccal surface, completing a double wrapped ligature. Sometimes the action of the muscles or the shape of the crown causes the rubber to slip crown-wise over the ligature. This is most apt to occur with light-weight dams and in the molar region. To obviate it, from two to four glass beads may be strung on the ligature and ar- ranged at effective points about the cervix of the tooth. Their bulk will prevent the rubber slipping over them. Dr. Fernandez suggests the use of short pieces of very small rubber tubing as being preferable to the beads. Dr. Wedelstaedt suggests tying a small roll of cotton in the ligature, to secure bulk. Usually a bulky knot, which may be tied in the thread before adjustment, on the lingual and the retaining knot on the buccal, will be sufficient. To be effective, ligatures must encircle the tooth at the cervical constriction. Carrying them to position is painful in some cases and painless in others, owing to the extent the gingival gum tissue must be forced rootward to allow the adjustment of the thread. As a rule the pain felt quickly passes away as the tissue recedes before the pressure of the dam and thread, but if it is severe and the ligature absolutely necessary, the rubber should be everted sufficiently to paint the gum- margin with a two per cent solution of cocaine hydrochlorate. The ligature may then be painlessly adjusted and by the time the efifect of the anesthetic has worn off, the gum tissue will have retracted suffi- ciently that pressure is relieved and further pain averted. No per- manent injury to the gingival margin need be feared unless the force used in adjusting the ligature is brutal enough to tear and lacerate the tissues, and with ordinary care the margin will return to its original position a few minutes after the removal of the rubber. In some cases, where there has been considerable recession of gum tissue and, perhaps, of alveolar process, and correspondingly large interproximal spaces present, instead of using ligatures, w-ads of ab- sorbent cotton may be packed between the teeth, holding the rubber to place. Whatever method is employed, the operator should be care- THE USE OF RUBBER DAM. 1 57 ful to remove all retaining material or appliances before attempting to remove the dam. Clamps. — Clamps are used to hold the rubber on the tooth and to keep it out of the way of the operator. If properly selected and adjusted they are harmless and not particularly uncomfortable but if not so selected and adjusted they may be detrimental to tooth-structure and soft tissues, and very painful to the patient. If the clamp is too small, the beaks may bite into the enamel; if it is too large or does not fit the tooth, it may be forced rootward and impinge seriously on the soft tissues; if carelessly adjusted the gingival tissue may be severely pinched by the beaks. The beginner should try each clamp on the tooth and note that it encircles the cervix properly, before attempting the adjustment of the rubber. A clamp which fits the cervix, even when carefully adjusted, may crowd the gum tissue rootwardstosome extent but, as with ligatures, no permanent injury will result and the tissue will resume its original position on removal of the pressure. Cocain may be used to deaden the pain of adjustment, if necessary. Two forms of teeth are especially difficult to clamp successfully, those excessively bell-crowned, on which the clamp tends to slide root- ward and impinge seriously on the gum tissue, and those short crowned teeth seemingly or really larger at the cervix than at any point crown- ward, from which the clamp tends to slip o£f occlusally. In both cases, a perfect fitting clamp will go far to remove the difficulty. Clamps have been devised for the bell-crowned teeth, with bows so arranged as to rest on the occlusal surface and prevent the slipping of the beaks rootward; and it has also been recommended that gutta-percha or other plastic material be placed between the clamp-bow and the occlu- sal surface, but none of these methods are efficient and a better plan is to dispense with the clamp and use a ligature. In many of the short crowned teeth it will be found that a cervical constriction exists if the beaks only reach it but that the gum tissue overlaps the cervix unduly. If this is not the case and the tooth-crown actually narrows occlusally, reliance must be placed on a perfect fitting clamp and caution during the operation that the clamp be not dislodged. In selecting the clamp for these cases preference should be given one with beaks having a decided rootward inclination, as is the casd with the Ivory number 14. With such a form the beaks pass between the crown and the over- lapping gum tissue until they reach the cervix, with a minimum amount of impingement on the soft parts. There are many sets of clamps on the market, all with some merit and each with their advocates. Ordinarily the operator will use one 158 EXCLUSION OF MOISTURE FROM TEETH DURING OPERATIONS. of a few standard clamps but a large assortment of special forms should be available to fit the extraordinary cases which occasionally present. Usually the only tooth on which a clamp is placed is the posterior one of those isolated and in adjusting the rubber on molars and bi- cuspids, when a clamp is to be used, the operator should begin with the tooth furthest back and work forward. Having selected the clamp best adapted to the tooth, the rubber should be adjusted on that tooth and the clamp placed in position by means of the clamp forceps. The difficulty experienced in practicing this method is that in proportion as the clamp is needed for the retention of the rubber, it is difficult to keep the rubber on the tooth long enough to adjust the clamp. To ob- viate this some operators stretch the rubber over the bow of the clamp, ad- just the forceps to the bow, gather up the rubber with the left hand and place the clamp in position on the tooth. The rubber is then stretched with the fingers until it slips under the beaks of the clamp and encircles the neck of the tooth. The objections to this method are that the rubber ob- scures the view of the tooth except in a few favorable instances where it may be held out of the way with the left hand sufficiently to permit of the crown being seen, and that stretching the rubber over the beaks often forces the latter down unduly on the soft tissues. The Ivory clamp was devised to meet these objections. This clamp has buccal and lingual flanges on the beaks, so arranged that the bow of the clamp may be passed through the hole in the rub- ber and the latter hung on the two flanges. The clamp with the rub- ber in position is now taken up by forceps designed for this purpose and adjusted on the tooth, the rubber being so stretched over the flanges as to bring the t(?oth-crown into view as the clamp is carried to place. The rubber is then slipped rootward from the flanges and encircles the cervix. Mesial projections on the beaks keep the rubber from obscuring the view of the mesio-cervical portion of mesial cavi- FiG. 109. — Ivory Clamps. ties. Cervical Clamps. — Buccal, labial and lingual cavities, with all THE USE OF RUBBER DAM. 159 or a portion of the cavity lying rootwards from the cervical line, re- quire the use of cervical clamps if any clamp at all is used. The wide range of location met with in these cavities renders it desirable that the operator have several forms of clamps to meet the differing condi- tions, although the mechanical improvement in some forms has been so great in recent years that they may be used successfully in widely varying cases by change of adjustment. The Ivory, Keefe and Dunn are all useful and have a con- siderable range of adjustment. The use of cervical clamps is often attended by much pain, due to forcing the soft tissues rootward sufficient to allow the beak a bearing on normal cementum. If possi- ble, the gum tissue should be retracted previous to the opera- tion by packing the cavity with gutta-percha. If the cavity is not of a retentive form the gutta-percha may be held in position with a wire or thread ligature. In superficial caries where this is impossible, the soft tissues may be divided by a longitudinal cut and the flaps pressed out of the way. On completion of the opera- tion the incised tissue should be pressed into apposition and gently massaged with the _ . Fig 110. — Brewer Clamp Forceps, nnger tip. I Rather than adjust a cervical clamp many operators hold the dam to'place with\ pointed instrument while filling the subgingival por- l6o EXCLUSION OF MOISTURE FROM TEETH DURING OPERATIONS. tion of the cavity and still others prefer to use absorbents in a manner to be described later, using amalgam for the subgingival portion in molars and bicuspids, and pellets or cylinders of non-cohesive foil in the anterior teeth, afterward adjusting the rubber dam and finishing the operation with the filling material indicated for the case in hand. In all cases where clamps and ligatures are used, as in all other steps in operations in the oral cavity, the comfort of the patient should be considered, and while the operator would grossly err in allowing his regard for the feelings of his patient to interfere with the perfect performance of the operation, it is often possible to save the patient annoyance and discom- nm, fort by the exercise of judgment and care. THE SALIVA EJECTOR, BIBS, ETC. Fig. III. — Ivory Cervical Clamp. In some cases the required posture of the patient or the location of the adjusted rubber dam interferes seriously with the swallowing of the saliva. Opera- tions on the upper molars, where the chin of the patient is elevated and the neck muscles tense, are examples of the first class, and the adjustment of the rubber on the lower molars illustrates the second class. In some cases, also, the mental state of the patient or the pain of excavation will result in an abnormal amount of saliva being delivered to the oral cavity. Whether due to larger amounts of saliva or to the inability of the patient to dispose of it by swallowing, the excess will drool from the mouth and should be cared for. Rubber bibs for the protection of the patient's clothing may be used or towels placed over the chest. The saliva ejector is of great help in these cases, by siphoning off the saliva. Occasionally a nervous patient will be found who objects to its use but many others will stand the pain of excavating and the strain of a long operation far better if they are instructed in the use of the ejector and allowed to manipulate it. The diversion of attention from the operation to the manipulation of the ejector is, of course, responsible for this. Fig. 112. — Keefe Clamp. RUBBER CUPS, COTTON ROLLS AND NAPKINS. As has been previously remarked, before the days of rubber dam, napkins and other absorbents were the only available means for the RUBBER CUPS, COTTON ROLLS AND NAPKINS.. l6l exclusion of saliva. In later years some efforts have been made to increase the efficiency of the methods employed in using absorbents but, in the opinion of the writer, they have been futile. By the old methods, absorbents skillfully manipulated will exclude saliva in nor- mal mouths for from twenty to thirty minutes, or longer, without distressing the patient. For short operations, such as redressing a pulp canal or inserting a temporary filling, this is more than ample time. The writer has seen large occlusal cavities in lower molars filled with non-cohesive cylinders and finished with cohesive foil while the saliva was excluded by the use of napkins. The subject of the exclusion of saliva by the use of other materials than the rubber dam may be divided as follows: — First, the use of rubber cups; second, the absorption of the saliva after it flows into the mouth; third, the prevention, partially or totally, of the delivery of saliva to the oral cavity. * Rubber Cups. — Rubber cups known as Denham's coffer dam shields, fashioned like the cups used for carrying pumice for polishing teeth, are used with some success for short operations. The base of the cup is of thin rubber. A hole is made in the base with the rubber dam punch and the cup adjusted on an Ivory or similar clamp. The clamp is then carried to place on the tooth and the rubber slipped over the flanges of the clamp as described in the use of rubber dam. In pulp canal treatment of lower teeth where the adjustment of the dam is particularly difficult, these cups may be used to advantage. The saliva ejector may also be used to assist in reducing the amount of saliva in the mouth. The Use of Absorbents. — Absorbing the saliva after it flows into the mouth may be accomplished by napkins or by specially pre- pared rolls of absorbent cotton. The manner in which this is done will readily suggest itself to the operator. The roll or napkin is ad- justed in a V shape with the free ends to the anterior, the bottom of the V just posterior to the tooth to be operated on and the roll resting against the buccal and lingual surfaces of the teeth. Special clamps, with large flanges, designed to clasp the roll or napkin and hold it firmly against the gums, may be had. Where this method of excluding saliva is efficient, the clamps are an advantage in that they permit the operator to use both hands. If the quantity of saliva delivered to the mouth is small, this method, in connection with the saliva ejector, may meet with success. The Exclusion of Saliva from the Mouth. — The older operators depended far more on the exclusion of the saliva from the mouth than 1 62 EXCLUSION OF MOISTURE FROM TEETH DURING OPERATIONS. on its subsequent absorption. This may be accomplished by stopping the salivary ducts at the point where they open into the oral cavity. For this purpose, napkins from four to five inches wide and about twelve inches long, are desirable. These may be cut from a piece of clean, bleached linen and thrown away after use'. The napkin should be folded longitudinally until it presents a width of an inch to an inch and a half. For operations on the right side below, the patient should be instructed to raise the tip of the tongue to the roof of the mouth and the napkin adjusted across the mouth from left to right, the end resting against the lingual surfaces of the teeth on the left side. The tongue tip is then lowered and the free end of the napkin carried from right to left over the dorsum of the tongue. Rolls or wads of absorbent cotton are then adjusted between the buccal surfaces of the upper molars and the cheeks, closing the openings from the parotid ducts. The fore- finger of the left hand resting on that portion of the napkin covering the dorsum of the tongue, is used to hold the tongue firmly against the floor of the mouth and the other fingers are used to hold the right cheek out of the way, the thumb being pressed firmly against the under part of the chin. If there is an excessive flow of saliva from the right parotid duct, the cotton covering it may be removed, when saturated, and a dry piece quickly and easily adjusted. This is, however, not often neces- sary. For operations on the left side below, the napkin is reversed, starting with the end resting against the lingual surfaces of the right teeth, passing under the tongue from right to left and over the dorsum from left to right. The forefinger of the left hand is now used to hold the left cheek away from the buccal surfaces of the teeth, while the other fingers depress the tongue and the thumb insures immobility by its position under the chin. Occasionally a patient will be found whose tongue involuntarily resists the effort to depress it but that ceases under firm, steady treat- ment. The napkin over the dorsum permits the operator to compel obedience from the tongue muscles that would be impossible with the bare fingers against the bare mucous membrane. By this method the secretion from the submaxillary and sublingual ducts is kept out of the mouth completely. Care must be exercised in removing the napkin for the mucous membrane dries so thoroughly it might be in- jured by roughness or haste. The difficulty in excluding saliva during operations on the upper teeth is much less. Here we only have the parotid duct to consider and the use of a napkin as described above under the head of the use of absorbents, is usually sufficient. It acts not only as an absorbent RUBBER CUPS, COTTON ROLLS AND NAPKINS. 163 but also lessens the quantity of saliva delivered through the parotid duct. In some cases it may be advisable to also use the ejector. A form of tongue depressor consisting of a duckbill arm to rest on the dorsum of the tongue, a suitably shaped shield to rest against the under side of the chin, and a ratchet arrangement whereby the depressor may be locked when the relations between the tongue and shield are such that the tongue is fully depressed, may be bought of dealers in surgical instruments and Dr. Henry A. King, of New York, produced a similar device on lighter, more graceful lines, in 1904. If the patient does not object to their use, these instruments permit of the use of the napkin, as described, with both hands free. CHAPTER X. PREPARATION OF CAVITIES FOR FILLINGS. BY A. E. WEBSTER, M. D., L. D. S., D. D. S. Definition. — Under this heading is included all those operations which have for their purpose the removal of carious tooth tissue, formation of cavities for the reception and the retention of fillings and the extension of cavity walls to prevent further decay. Nomenclature. — In every nation or class of people living and associating together is developed a system of signs or sounds by which ideas are communicated to each other. This is their language. In every business or trade or occupation there is similarly developed a system of signs, words and names which are used by those engaged in the same trade or occupation as a means of communication. These signs and names are termed the nomenclature of the trade or profession. Without such a code those in the same occupation would not be able to understand each other. So in the subject of the preparation of cavi- ties it is necessary to have a system of names and signs which all must understand before communication is possible. The majority of the names used in the preparation of cavities will be familiar to those who have studied dental anatomy. Others will be defined. The nomen- clature followed will be that adopted by the Institute of Dental Peda- gogics. Cavity Nomenclature. — Cavities in teeth take the names of the surfaces of the teeth in which they occur. Labial cavities occur in labial surfaces. Buccal cavities occur in buccal surfaces. Lingual cavities occur in lingual surfaces. Occlusal cavities occur in occlusal surfaces. Mesial cavities occur in the surfaces of the teeth looking toward the median line. Distal cavities occur in the surfaces of the teeth looking away from the median line. Proximal cavities are those which occur in the proximal surfaces of the teeth. Cavities which involve more than one surface take the name of the two or more surfaces involved, thus: 165 l66 PREPARATION OF CAVITIES FOR FILLINGS. Mesio-occlusal cavities involve both the mesial and the occlusal surfaces. Disto-occlusal cavities involve both the distal and the occlusal surfaces. Mesio-labial^ cavities involve both the mesial and the labial surfaces. Mesio-lingual cavities involve both the mesial and the lingual surfaces. Disto-lingual cavities involve both the distal and the lingual surfaces. Mesio-occluso-distal cavities involve the mesial, occlusal and the distal surfaces. Other combinations may be made to describe the location of cavities. CLASSIFICATION OF CAVITIES. Teeth usually begin to decay in defects of the enamel surface or on smooth surfaces not kept clean. Thus they may be divided into two general classes; pit and fissure cavities, and smooth surface cavi- ties. Pit and fissure cavities do not require to be extended beyond the limits of decay or the defect in the enamel, while those on smooth sur- faces usually require to be extended sufficiently to bring the margin of the filling to a point on the tooth's surface where it is kept clean either by the excursions of food or by the actions of the lips or tongue. Pit and fissure cavities occur in the lingual surfaces of upper in- cisors and occasionally in cuspids, and in the occlusal surfaces of bicuspids and molars and the occlusal and middle thirds of the buccal and the lingual surfaces of molars. The classification of cavities which follows requires a similar method of treatment for each class. Pit and Fissure Cavities. — Cavities in the occlusal and middle thirds of buccal and lingual surfaces of molars. Cavities in occlusal surfaces of bicuspids and molars and lingual surfaces of upper incisors and occasionally upper cuspids. Smooth surface cavities occur in the surfaces not kept clean and may be classified as to location as follows: 1. Cavities in the gingival third of labial, buccal, and lingual sur- faces. 2. Cavities in proximal surfaces of incisors and cuspids which do not involve the incisal angle. NOMENCLATURE OF THE INTERNAL PARTS OF CAVITEES. 167 3.. Cavities in the proximal surfaces of incisors and cuspids which do involve the incisal angle. 4. Cavities in proximal surfaces of bicuspids and molars which do not involve the occlusal surface. 5. Cavities in the proximal surfaces of bicuspids and molars which do involve the occlusal surface. NOMENCLATURE OF THE INTERNAL PARTS OF CAVITIES. The surrounding walls of a cavity take the names of those surfaces of the teeth toward which they are placed, thus an occlusal cavity has a mesial wall, a buccal wall, a distal wall, a lingual wall and a fifth wall which is known as the pulpal wall. The pulpal wall of a cavity is that wall which is occlusal to the pulp and at right angles to the long axes of the tooth. If the pulp be re- moved the floor of the pulp chamber becomes a wall of the cavity and is known as the sub-pulpal wall. In cavities occurring in the axial surface that wall covering the pulp is called the axial wall and if the pulp be removed the wall takes the name of the w^all of the pulp cham- ber. Cavities in the axial surfaces of teeth have mesial and distal, or buccal and lingual walls, and an occlusal and a gingival wall, and an axial wall. In complex cavities which involve the axial and occlusal surfaces the gingival wall is termed the seat of the cavity and the pulpal w^all is known as the step. For purposes of convenient description cavities in teeth are supposed to be cuboid in form. Where two walls join, a line angle is formed taking the name of the two walls entering into its formation, thus: Bucco-pulpal line angle or gingivo-axial line angle. Where three walls join, a point angle is formed taking the name of the walls entering into its formation, thus: Gingivo-labio-axial point angle or gingivo-linguo-axial point angle. The enamel wall of a cavity is that portion of the wall between the cavo-surface angle and the dento-enamel junction and includes the thickness of the enamel. The dentin wall is that portion of a cavity which is lined with dentin. The enamel margin includes the whole outline of the cavity and is equivalent to the marginal line of the cavity. The cavo-surface angle of a cavity is the angle formed by the junc- tion of the wall of the cavity with the surface of the tooth. l68 PREPARATION OF CAVITIES FOR FILLINGS. THE PLANES OF THE TEETH. The horizontal plane is at right angles to the long axis of the tooth. Mesio-distal plane is parallel with the long axis and passes through the tooth from mesial to distal. Bucco-lingual plane is parallel with the long axis and passes through the tooth from buccal to lingual. The bevel of the cavo-surface angle is reckoned from the plane of the enamel wall. DIVISIONS OF TEETH AND CAVITIES. For convenience of locating a cavity on the axial wall of a tooth the tooth may be divided into thirds, and known as the occlusal third, middle third and the gingival third. Cavities in teeth may be divided in the same way either in the horizontal plane or in the mesio-distal plane, thus: A buccal cavity is located in the gingival third in the horizontal plane, and in the middle third in the mesio-distal plane. STEPS IN CAVITY FORMATION. The beginner in any mechanical work does not at once arrive at the best and most expeditious methods of procedure. But after a time if he be an observing person he will fall into an order of procedure which he will follow more or less rigidly. Hence it is important that he should at first at least follow those who have had opportunities of developing the best methods. The Institute of Dental Pedagogics has given the following steps in cavity formation as those fulfilling the greatest number of requirements. 1. Establish the outline of the cavity (outline form). 2. Remove the softened decay. 3. Give the cavity proper form. Which includes convenience form, resistance form and retentive form. 4. Bevel and polish the enamel wall. 5. The final touches or the toilet of the cavity should include a care- ful observation of the condition of the tooth tissue over the pulp and a thorough cleansing of the cavity surfaces. General Consideration of Outline Form. — Before a dentist is justified in undertaking the treatment of a patient's teeth for the purpose of eradicating present caries and the prevention of fu- ture decay he should consider well all the factors which enter into the causation of decay and its prevention. The family history and the personal history of caries are of value in deciding the character of the operations to be performed. Family Traits. — ^In some families even though there be many cavi- ties while young, they yield to treatment and fillings have a degree of STEPS IN CAVITY FORMATION. 169 permanency not found in others of more favorable appearance. Then again caries in some famihes rarely appears before the fifteenth year while in others it begins at the appearance of the deciduous teeth. Caries will cease at the twentieth year in some families and not recur until perhaps the fiftieth year or perhaps not at all. Patients giving a family history of immunity after a certain age and a personal history of immunity at the same age need not have what are sometimes called heroic operations done for them. The greatest attention in such cases should be given to the prevention of present decay rather than that which may occur in the future. Such conditions might influence to a large extent the location of the cavity margins. Physical, Mental and Personal. — ^The physical, mental, and personal habits have a great influence on the character of operations that should be performed. Many patients apply for dental treatment who are not in a fit physical condition to have ideal dental operations performed. A dentist would be lacking in judgment who would ask a frail girl ma- turing into womanhood to submit to having the outline of many proxi- mal cavities carried through sensitive tissue to bring them to a clearing margin. Then again there are those who are so weak mentally that it takes careful management to preserve their teeth at all. They think they cannot bear anything in the way of inconvenience. Such patients need the strong controlling force of a man who knows just how to handle them before he may venture to do ideal operations. Natural Cleanliness. — Some patient's teeth are kept perfectly clean apparently without an effort. They eat proper foods and masticate them well, which is a factor in preventing caries. Almost all surfaces of the teeth are kept clean and are consequently immune to caries. If caries does occur the cavity margins do not require to be extended appreciably to meet areas which are immune. Others have teeth which always seem to have what might be called a scum over them, with cavities occurring in every defect of enamel and on surfaces which would be immune in other mouths. Where decay seems so progres- sive, cavity margins must be extended until they reach the immune areas of the tooth's surface even though much of the surface must be covered by filling. Month Appearance. — ^The very appearance of the mouth often helps the operator to choose the character of operation. A certain viscid tenacious saliva, abundant in quantity, usually indicates rapid decay and demands that the outlines of the cavity should be extended far beyond the areas of contact with the other teeth. Many points of white or yellowish- white decay on smooth surfaces especially in labial. T70 PREPARATION OF CAVITIES FOR FILLINGS. buccal, and lingual surfaces is indicative of a marked susceptibility and demands free extension of cavity outlines, while if the cavities be dark brown or black in color and are found only in fissures the outlines need not be extended so freely. Because of the difficulty of keeping irregular teeth clean cavities in such cases should be extended fully. It resolves itself into this, in all cases where decay occurs, that part of the tooth's surface which is not kept clean about the cavity should be included within its outline. I. The outline form is the form of the area of the tooth's surface to be included within the outline of enamel margins of the finished cavity. The first step in the preparation of any cavity is to decide as far as possible the extent of the caries which in a measure helps to locate the outline of the cavity. The extent of the caries helps to locate the outline only in simple pit cavities, and those occurring in exposed surfaces and those which are so large as to have involved all the defects of enamel and susceptible areas of the tooth's surface under consideration. To find out the extent of the caries it is necessary to break down the enamel not supported by dentin except perhaps where it may be left for esthetic reasons as in labial and buccal cavities in incisors, cuspids and bicuspids. The loosened and soft decaymay be removed and the cavity washed out with a stream of tepid water. This will so clear the field of operation that a better judgment can be made as to the amount of sound tissue remaining, the condition of the pulp and the proper location of the outline. In the further preparation of the cavity it is well to have the rubber dam in position or use some other means of keeping the cavity dry. (a) In fissure cavities the outline must include all the fissures and angular grooves radiating from the caries even though the cavity be but small. Such a cavity usually begins because of a defect in the continuity of the enamel surface and if only the carious portion be re- moved and a filling inserted the defective fissures remaining are just as likely to decay as originally. It is found that unless filling materials are polished flush with the enamel surface the thin edge left over the margins will likely be a point of leakage and later decay. If angular grooves are left radiating from a cavity it is impossible to so polish the filling that none will be left over these margins, hence it is better to cut them out and include them in the cavity. (b) Superficial defects of the enamel about cavities should be cut out until sound enamel is reached and in some cases until full length rods are reached. In many cavities occurring about the gum margins there is an area of whitened or defective enamel passing around STEPS IN CAVITY FORMATION. 17I the tooth which if not cut out and included in the cavity will decay in a short time and cause the loss of the filling, and perhaps the confi- dence of the patient in filling operations. In some of these cases the outer ends of the rods are worn away or lost by the effects of superficial decay and are likely to cause the failure of the filling if the margin pass across it. (c) Extension for Prevention. — The general rule laid down for locating the margins of cavities which occur in proximal surfaces is to extend them to such a point on the tooth's surface that the joint between the filling and the enamel may be in immune areas. There may be some exceptions to this rule in rare cases but if cavity margins are allowed to come against adjoining teeth the fillings cannot be con- sidered more than temporary. Any one who has practised dentistry for more than a few years cannot help having observed the wisdom of extending all proximal cavities buccally, lingually, and gingivally far enough to bring the margins to such a point on the tooth's surface as will ensure their being kept clean or protected by healthy gum tissue. It makes but little difference whether the cavity be small or large in a proximal surface the outline should be well beyond any contact with the adjoining tooth. This extension of cavity walls through sound tissue to bring the margins to immune areas is known as extension for prevention. (d) A developmental groove or another cavity should not be allowed to come too close to enamel margins. It is better in such cases to cut out the groove and include it in the cavity. The rods of the enamel in such cases usually stand at right angles to the surface which is faced away from .the cavity, so when the cavity is prepared they are left without support. If only a small portion of enamel be left between a cavity and another filling it is almost certain to become a source of weakness to both fillings. Such enamel is usually more or less undercut and unsupported by dentin and the seat of fracture during the insertion of the gold. (e) The buccal and lingual margins of proximal cavities in bi- cuspids and molars should be as nearly parallel as possible and at right angles to the seat of the cavity. Such a preparation makes the gin- gival wall more accessible to start and condense the first portion of the filling. Besides it brings the outline into full view during the building of the filling. If these margins and the walls of the cavity adjoining them are parallel the filling material as it is condensed will not draw away from the margins as in divergent walls, or tend to fracture the tooth as in convergent walls. 172 PREPARATION OF CAVITIES FOR FILLINGS. (f) The outline in all cavities should be straight lines or regular curves because it is much easier to adapt a filling material to a regular margin than to an irregular or ragged one. Besides they are said to be more esthetic, which is doubtful, but at all events they look more like the work of a good mechanic. Technique. — To obtain the proper outline of a cavity it is nec- essary to break down and remove all enamel not supported by dentin. The straight chisel in the hand well guarded against slipping will cut away enamel readily if the edge of the blade is made to insinuate itself between the rods. The force should be applied in the direction of the long axis of the rods. In some cases the sharp edge of the blade may be placed against the wall of enamel and the edge snapped off piece by piece (Fig. 113). In others the edge of the chisel may be placed against the enamel and given a quick decisive blow with a mallet which will readily fracture the enamel (Fig. 114). It is well to be careful not to attempt to cut off more at once than will easily be cleaved away on account of the shock from the mallet which may be painful to the patient and come with such suddenness as to cause doubt of the operator's skill. A chisel in the automatic mallet will often break enamel, but like hand pressure it is difficult to control. A chisel in an engine mallet will break enamel rapidly and is under control but violent on the patient if a blow is given against the enamel which does not chip off. The final planing of the enamel wall to bring it to evenness must be done with a chisel. Cavities in proximal sur- faces which -require extension through sound tissue are best enlarged by cutting the dentin out under the enamel with a comparatively small bur and then breaking down the enamel with the chisel. Cutting out fissures. — Fissure cavities can be extended in undecayed enamel by cutting a narrow slot through the groove with a small dentate fissure bur ground at Fig. 114. the point on two sides to make it into a drill. A wornout, inverted cone bur ground to the same form will cut equally well. If the hand-piece be given a swaying motion and the point kept sharp even perfect enamel can be cut rapidly. If it be found that the dentin is not very sensitive the drill point may be directed rather under the enamel which seems to undermine it and allow it to cut easier. It is important that the drill be small, a large drill imparts too much jar to the tooth. Even the smallest size of an inverted cone bur so ground will serve every purpose because once the enamel STEPS IN CAVITY FORMATION. 1 73 is broken the edges may be chipped in with a chisel or a hatchet excavator. A small thin edged carborundum disk in the straight hand piece for bucco-lingual fissures and in the right angle for mesio- distal fissures will open them up rapidly and with less discomfort to the patient than fissure burs. In certain large distal cavities in molars the buccal and lingual walls cannot be reached with a straight chisel and a curved chisel with a narrow blade cannot be controlled if force enough be applied to fracture the enamel. The blade is almost certain to drop into the cavity and touch sensitive dentin or perhaps wound a living pulp. An instrument made on the. form of a broad axe, with the blade short and wide and parallel with the long axis of the shaft will successfully break such enamel walls without danger to the pulp or the gum tissue. In smooth surface cavities in exposed positions the outline may be extended with dentate inverted cone burs by placing the base of the cone against the axial wall and carrying the corner of the bur under the enamel. In this way the foundation of the enamel is cut first leaving it easily cleaved away. Final Trimming and Planing. — ^The final trimming or planing of the enamel wall is done with broad bladed chisels holding the width of the blade parallel with the long axis of the rods. Black's side in- struments will shave the buccal and lingual enamel walls of molars, while the gingival is best reached with a Darby-Perry chisel. The enamel walls of pit and fissure cavities are best trimmed with fissure burs run rapidly and held at right angles to the pulpal wall. If access to the cavity is reasonably good, a thin carborundum disk will rapidly cut back the buccal and lingual walls and leave a smooth regular sur- face. A cone-shaped carborundum stone with a square end in the right angle will extend the dentin of both walls and square the seat at the same time. 2. Softened and decalcified dentin should next be removed from the cavity. In certain rare cases a portion of hard, discolored dentin may be left when its removal would expose a living pulp. In such cases a non-irritating disinfectant should be used for sufficient length of time to insure disinfection before the filling is inserted. Technique.— The manner of removing the remaining decayed tissue depends upon the character of the tissue, the size and location of the cavity and the sensibility of the dentin. In shallow cavities in exposed surfaces where the dentin is usually sensitive a deep decisive cut with a hatchet excavator in one corner of the cavity, followed by prying up or scooping out of the tissue in one layer is less painful than 174 PREPARATION OF CAVITIES FOR FILLINGS. to attempt to remove the tissue in small pieces. In large cavities when the decay reaches close to the pulp it is better to go around the edges with spoon excavators flaking up the decay and peeling the layers off without making much pressure. After the decayed tissue is well removed down to the solid dentin at all points except where the pulp comes nearest to the cavity, then take a large spoon excavator and carefully scrape away the decalcified dentin until hard tissue is reached. This can be done without pain to the patient if little or no pressure is applied. Usually in these cavities it is the dentin at the dento-enamel junction which is most sensitive. In certain cavities of dark brown or black decay where the tissue is hard, as occasionally occurs in occlusal cavities in molars in old patients, the decay may be most rapidly removed with burs. In no case should burs be used close to the pulp. In fact burs are of little or no value in removing decayed tissue except where it is hard. Spoon excavators are of most general use, though hatchets and burs may be used in special cases. 3. A cavity may be considered of proper form when it is so shaped that it can be conveniently filled, when it will retain the filling and when its walls will resist any stress which may come upon them. (a) For convenience a cavity should be so formed that all its walls may be seen directly or brought into view with the mouth mirror. Grooves and undercuts should be avoided in a completed cavity form. They are always difficult to fill and add very little to the retention of the filling, and are a source of weakness to the walls. Line angles and point angles should not be so small and acute that instruments cannot reach their depths. Proximo-occlusal cavities in molars and bicuspids are in their most convenient form for filling when they are so shaped that they will retain the filling and resist the stress of mastication. If such cavities have a flat seat and step, parallel buccal and lingual walls and a dovetail in the occlusal surface, they are then convenient to fill with whatever material is desired. Cavities in incisors and cuspids require perhaps some slight modification of a gingivo-labio-axial point angle and gingivo-linguo-axial point angle to make it possible to more conveniently start a gold filling. These angles are made more acute and the corner is cut more deeply than is necessary for retention. They may be truly called convenience angles. In some cavities difficult of access it is often more convenient to cut away a wall or to extend an outline so as to bring the walls into full view. The labial surfaces of incisors and cuspids should not be cut away for convenience of access to a small proximal cavity. In the majority of these cases it is better to separate the teeth until access STEPS IN CAVITY FORMATION. 1 75 can be had to properly prepare the cavity and insert the filling, while in other cases the lingual surface may be cut into for convenience of access. Technique. — The general technique of obtaining the outline form having been described it is not necessary to discuss more than what is specially done for convenience. A cavity with a good outline is easily filled. In many cavities having penetrating decay it will often be more convenient to fill any irregularities or pits not used for retention with cement, leveling up the walls. Often a buccal plate of enamel in a mesio-occlusal cavity in an upper bicuspid is left for appearance sake though the dentin is gone from beneath it. The loss of the dentin leaves such a deep groove at the junction of the axial and buccal walls that it is very inconvenient and difficult to fill it with gold. In such cases it is much better to fill the grooves with cement and square up the buccal and lingual walls so that they may be parallel. For convenience of starting a cohesive gold filling in proximal cavities in incisors and cuspids a No. ^ or No. i inverted cone bur, which is held parallel with the long axis of the tooth as it is carried from labial to lingual to form a flat seat for a filling, may be swayed toward the labial as it is carried to the labio-gingivo-axial angle, and as the bur approaches the depth required it should be swayed to the lingual and carried slightly toward the incisal. By this movement a deep acute angle is cut which has the general direction of the greatest amount of tooth tissue avoiding the pulp. This acute angle is in a like manner cut in the gingivo-linguo-axial angle. With acute angles cut in opposite walls in the seat of any cavity there should be no difficulty in starting a cohesive gold filling. These may be truly called con- venience angles though they are large enough to assist in the retention of the filling. These angles are easily filled and securely hold the gold in position while more may be built upon it. The small pits drilled at random in the seat of the cavity as has been too often the practice are difficult to fill and not always secure when filled. There seems to be a growing tendency among operators who do not wish to expose gold on labial surfaces to cut the lingual surface freely away, making a dovetail in the enamel for retention. This is really a convenience form. (b) Resistance form is .that shape given a cavity intended to afford such a seat for the filling as will best enable it to withstand the stress brought upon it in mastication. Its importance depends upon the area of the surface of the filling exposed to occlusion, and the strength of the closure of the jaws. The general rule in foundation 176 PREPARATION OF CAVITIES FOR FILLINGS. construction is to keep as nearly a flat base as possible. Foundations made to resist heavy weights and tipping stress are flat. A cone- shaped base in a pulpless bicuspid or molar decayed mesio-occluso- distally has often been the cause of a fracture of the root. In such cases the filling acts as a wedge, cleaving the weaker wall. The seat of occlusal cavities should be flat and at right angles to the stress coming upon it, likewise cavities in proximo-occlusal surfaces of molars and bicuspids should have a flat seat and step to resist the heavy stress of occlusion and the tipping stress which comes upon these fillings. It is not often realized by operators how much stress some fillings may be called upon to resist. In strong men a single molar may occasionally have a force of from two hundred to two hundred and fifty pounds applied to it. The closure of incisors of course is much less, but the anchorage for a filling in these teeth is less. The biting off of a crust of bread and its mastication will involve a pressure of from 100 to 150 lbs., while an ordinary beefsteak requires seventy-five pounds of pressure on an area the size of the human teeth to cut through it. In accidents of a piece of lead in canned goods, or shells or bones in flesh, a filling may receive the whole weight of the closure. Pulpless teeth, crowns and dentures have much less force applied to them than normal teeth. It would seem that when the pulp of a tooth is lost the pericemental membrane loses some of its power to resist pressure without injury. Hence fillings antagonizing with pulpless teeth crowns and dentures need not be so securely seated as those opposing sound teeth. In deciding what amount of seating a filling should require the force of the closure of the jaws must be well studied. Also the teeth antagonizing the filling and the area of the filling exposed to occlusion. It is obvious that labial, buccal, lingual, and small proximal cavities in incisors and cuspids do not require to be securely seated because the surfaces of these fillings are not exposed to the forces of mastication. No one thing has done more for the stability of fillings than the study of the forces of the closure of the jaws and the introduction of proper methods of seating fillings to resist that force. Technique. — The inverted cone bur, the fissure bur, the chisel, the hatchet and the hoe excavators are the only instruments which can be used to form a flat seat in cavities to resist the force coming upon the filling. Round burs and spoon excavators have no place in form- ing the seat of a cavity. The seat, the step, and the lateral walls must be definite, joining each other with right angles or acute angles. The seat in molar and bicuspid cavities may be cut flat from buccal STEPS IN CAVITY FORMATION. I77 to lingual and from the enamel margin to the axial wall with an in- verted cone bur about one millimeter in diameter. As this bur is carried back and forth from buccal to lingual there is often some difficulty in keeping it from jumping out of the cavity, and perhaps winding up the septum of rubber dam between the teeth, or wounding the gum, or perhaps cutting dangerously near the pulp. The diffi- culty of holding a bur in such a position is increased with the increase of the size of the bur and also by placing it in the right-angled hand- piece. If, after all the overhanging enamel is broken down and the softened decay removed, the Ivory or Hinicker matrix be adjusted, a bur can then be held in the base of the cavity without fear of accident in one direction at least. It is generally well to use a small bur, cutting the dentin only, and then cut away the enamel with Black's side instruments or Darby-Perry chisels. This will leave a wide flat seat. The step is usually partly formed with cement and as the last part of its formation an inverted cone bur in the right angle may be carried over the whole step. The seat of incisor cavities is formed in the same way only using much smaller burs; about a half millimeter inverted cone is more suitable for laterals and some centrals, (c) Retention form is that shape given a cavity which will prevent the filling from being dislodged. This is largely provided for in the resistance form and to some extent in the convenience form, but in certain cavities the filling might resist the direct stress upon it and yet be easily displaced with slight lateral force. Retention form is pro- vided for in proximo-occlusal cavities in molars and bicuspids by a dovetail in the occlusal surface and by providing parallel w-alls or perhaps walls slightly undercut. Proximal cavities in incisors and cuspids which do not involve the incisal angle do not need more than a flat seat deepened at the gingivo-labio-axial and gingivo-linguo- axial angles, with a slight undercut at the junction of the labial and lingual walls at the incisal. Cavities which involve the incisal angle should be provided with a step if much stress is to come upon the fillings. For many years operators have been chiefly concerned in the retention of fillings, only having regard to what might tip them from the cavity, not thinking that the greatest force in dislodging fillings is the direct stress of the closure of the jaws. The more fillings failed the more and the deeper were made the pits, grooves and under- cuts. The pits did not contain enough filling material to have strength to resist the stress, and the grooves and undercuts often cut clear through the dentin, leaving only the enamel for retention which frequently fractured. The thoughtless operator has an idea that^if 178 PREPARATION OF CAVITIES FOR FILLINGS. he uses a large round bur in the center of the tooth making the cavity larger inside than at the margins the filling cannot get out. This might succeed if the enamel were not so friable when unsupported by sound dentin. The surest way to make a cavity which will retain a filling is to study carefully the forces which may come upon it to dislodge it. Estimate the strength of the cavity walls and then so shape the cavity that its seat or foundation will be opposite the stress applied and its retention cut in the direction of the greatest amount of dentin, and if undercuts are used place them in opposite walls of the cavity. In general the retention should be as near the point of stress as possible, and the area of the seat and step equal to the area of the filling exposed to the occlusion. Technique. — A cavity is usually shaped to resist tipping stress with the same instruments as are used to make the resistance form. Occlusal cavities in molars and bicuspids require parallel walls, and at opposite points a slight undercut which can be made with the inverted cone bur as its shaft is held at right angles to the pulpal wall. The only force which might remove this filling would be a lifting force from the adhesion of some sticky substance such as taffy. Proximo- occlusal cavities in molars and bicuspids cannot be retained to any extent by grooves or undercuts. The dovetail in the occlusal surface which is easily cut with a cross cut fissure bur or inverted cone bur is all that is necessary. In some bicuspids retentive form may be obtained in the occlusal surface by deepening the step at the point farthest from the proximal cavity with an inverted cone bur slightly undercutting the buccal and lingual walls. Proximal cavities in incisors and cuspids may have grooves extending out from the point angles for retention. As the inverted cone bur is sunk into the angles it may be carried up the labial and lingual walls a short distance making a groove. In many of these cases an obtuse angle hatchet or hoe may be used to cut a definite angular groove in these walls. The retention towards the occlusal is best cut with a small contra- angled hatchet excavator. No. 27, S. S. W., is a very suitable size. 4. The proper bevel and polish of the enamel wall of a cavity is of prime importance because the permanency of the filling depends so much upon the joint between the filling and the tooth. A good working knowledge of the histology of the enamel is essential to obtain the correct bevel of the enamel wall at all points. The enamel is composed of rods cemented together by a less dense substance than that composing the rods. In consequence of the cement- ing substance being less strong than the rods the structure is likely STEPS IN CAVITY FORMATION. I^q to cleave between the fibers. The rods are difficult to cut across or hard to wear down from their ends but easily split, if the cleaving force is in the direction of the long axis. This is of importance in breaking down enamel to open into a cavity. If a chisel be directed against the enamel so that the rods are split apart little force is re- quired. The rods are more or less parallel in their outer half while in their inner half they are interlaced and tangled together. In some teeth the rods radiate from the dentin almost parallel, while in others they are wavy and are interlaced a great deal. It is this variation in the interlacing of the fibers that accounts for the difference in the degree of resistance enamel has for cutting instruments. It was formerly believed that enamel which was very resistant to cutting instruments was harder because it contained more lime salts than that which cut more easily. This was shown to be a fallacy by Dr. Black, who demonstrated that the so-called soft teeth had not less lime salts but seemed to be soft because the enamel rods were straight and consequently easily split apart, while the so-called hard teeth were merely hard because the fibers of enamel were interlaced and tangled together much like the fibers of wood in a pine knot, and any attempt to cleave them is difficult because no matter in what direction the attempt is made the rods must be cut across. The direction of the enamel rods may be said to be from the center of the tooth to the surface. The rods are generally perpendicular to the surface but there are many locations where they approach the surface at a decided inclination. At a line about the center of a molar or bicuspid the rods are perpendicular to the surface, but as the occlusal surface is reached the rods become more and more inclined toward the cusps where they become parallel with the long axis of the tooth and perpendicular to the tip of the cusp. Likewise as the gingival is reached the rods become more and more inclined toward the root. It is clear from these facts that a cavity in an axial surface coming close to the cusp or marginal ridge cannot have its occlusal wall perpendicu- lar to the axial surface without leaving many enamel rods not sup- ported by dentin. A decided bevel should be given enamel walls at these points which may make the filling material so thin that it may flare up from the margin. Any attempt to make an occlusal wall of a cavity close to the occlusal surface is fraught with many chances of failure. It is usually advisable to cut through to, and include some of, the occlusal surface. The enamel rods incline toward pits and fissures and as they pass from a fissure in the occlusal surface of a bicuspid or molar toward l8o PREPARATION OF CAVITIES FOR FILLINGS. the cusps, the rods incline more and more until they are perpendicular to the tip of the cusp. Thus a groove or fissure which is not cut out very widely requires only parallel walls to protect its margins, while a cavity in the occlusal surface of a bicuspid which is cut widely enough to approach the cusps needs a good deal of bevel. In incisors and cuspids a line around the crown at the junction of the gingival with the middle third will find the rods pretty generally perpendicular to the tooth's surface. But as the incisal is reached the inclination of the rods becomes greater and greater until they reach the cutting edge where they are parallel with the long axis of the tooth. The inclination in the incisal third is often as much as 30 to 40 degrees. In proximal surfaces the degree of inclination of the rods depends upon the abruptness with which these surfaces join the incisal edge. The more rounded the corner the more the rods are inclined toward the incisal. Thus on the distal surfaces of laterals the inclination is greater than on the mesial surface. Proximal cavities coming close to the incisal edge in these teeth require so much bevel to remove the short rods that the margin of the filling is endangered by being too thin. Passing around the incisors and cuspids the rods are generally perpendicular except at the junction of the proximal and lingual surfaces, where the rods are inclined towards the marginal ridge and become rapidly inclined the opposite way on the lingual, and con- sequently when this ridge is approached it should be cut well back because the rods are not supported. Cavity walls cut in the incisal surface of incisors and cuspids are well protected even though* not brought down on the labial or lingual surfaces because of the inclination of the rods. Since the enamel rods are not always parallel with each other nor always at right angles to the plane of the tooth's surface, and since all filling materials are not always of equal strength with the enamel, it is not advisable to make the cavo-surface angle a right angle. But instead the outer half of the enamel wall should be cut back until the angle formed by the junction of the enamel wall and the tooth's surface should be greater than a right angle. The number of degrees greater depends upon the inclination of the enamel rods, the friability of the enamel, the force to come against it and the kind of filling material to be used. Gold fillings have the greatest protecting power for enamel walls and are the most likely to cause fracture or crumbling of the edge during insertion, consequently cavities prepared for the insertion of gold require more bevel than those prepared for amalgam STEPS IN CAVITY FORMATION. l8l or porcelain. Cavities prepared for gold, where much force may come upon the edges and the enamel is friable, require more bevel than cavities which occur in surfaces where less force may fall. Teach- ers and writers of operative dentistry have always said much on beveling enamel walls but rarely given the student any adequate idea of how much bevel a wall should receive. This idea is hard to impart in words unless accompanied with diagrams and a statement of the number of degrees. Every student has an idea of what a right angle is, and he knows when a cavo-surface angle is a right angle. Now if he will divide a right angle into sixteenths, eighths, sixths, and fourths he will have an idea what is meant when the bevel is to be 5 to 25 degrees. This means that the cavo-surface angle is 90 degrees plus the number of degrees of bevel (which is for example 25) or 115 degrees. As a rule when a lecture is given to a class of students on beveling enamel walls there will be many of them go to the extreme in bevels. This must be guarded against lest the filling material be too thin on the edge. Technique. — Beveling and smoothing enamel walls require so much skill and deft manipulation that it is only after repeated trials in cases where the results can be examined with a large magnifying glass that an operator can be at all sure of results. A disk is the most suitable instrument to bevel and polish enamel walls but unfortunately its range is limited. There are really but few cavity walls which can be reached at the proper angle with a disk. It will reach the labial, lingual and buccal enamel walls in large proxi- mal cavities but not the gingival, and only occasionally the occlusal The beginner is certain to round the cavo-surface angle with a disk unless he bears in mind that the disk must not be pressed against the wall, but must be held in position to cut the rods parallel with their long axis, allowing no wabbling of the hand-piece, mandrel or disk. When the rods are thus cut the hand-piece is held at the necessary angle to cut the bevel required. Often too much bevel is cut in large proxima cavities, by allowing the disk to go too close to the gingival wall. At the junction of the gingival wall with the proximal walls the rods are in such a direction that the disk cannot possibly reach them to give them the proper bevel. The gingival enamel wall must be trimmed and beveled with a bur or chisel. A disk in the right angle will reach en- amel walls in molars and bicuspids to better advantage in many cases than the straight hand-piece. j The next most suitable instrument and the most universally applic- able is the chisel. As the walls are planed down parallel with the l82 PREPARATION OF CAVITIES FOR FILLINGS. long axis of the rods they may then be shaved down to the proper bevel. The instrument must be held firmly and not allowed to turn or catch and jump as it is carried along the enamel wall. The bur is very universal in its application in trimming and beveling enamel walls but can never leave as smooth and uniform a margin as the disk. In all small cavities in pits and fissures, and in labial and lingual surface cavities it is the only instrument that can be used. In the majority of such cavities the walls are cut back with a bur as the cavity is being prepared. The bevel may be made with a straight cut fissure bur run rapidly. The gingival enamel wall in proximal cavities may be best trimmed with a round bur, and it is recommended by Johnson for trimming the walls in occlusal cavities in molars and bicuspids. The strip has a very limited use in smoothing enamel walls. It may be used in proximal cavities in incisors which do not involve the incisal edge but extend well onto the labial and lingual surfaces. In this position a strip held tight and passed back and forth from labial to lingual without allowing it to be lapped around the tooth will smooth the margin as nothing else will. 5. The toilet or putting the final touches on the prepared cavity should include a close scrutiny of the condition of the tissue covering the pulp and removing any dust or chips which may have collected in the cavity. If the cavity wall be at all close to the pulp it is well to go over it with a large, sharp spoon which will remove any remaining de- calcified dentin. Some care is needful lest so much pressure be applied as will cause pain. It is usual to cover such a pulpal or axial wall with cement and then form this up as if it were a wall of dentin. The cavity may now be dried thoroughly from a blast of warm air which will remove loose chips, but if moisture has been allowed in the cavity some of the chips will be so attached to the walls and crevices that they will not be removed by a blast of warm air. In such cases a piece of dry cotton rubbed around the walls will loosen the debris and then it can be blown away. Alcohol is often used to assist in drying a cavity but in sensitive teeth the patient receives a shock from the rapid evaporation of the alcohol. INSTRUMENTS. While it is of importance to know how to prepare a cavity it is of almost equal importance to know what instruments to use and how INSTRUMENTS. 1 83 to use them. The study of instruments and how to use them is no small part of the preparation to practise dentistry. We are known by our tools. A fifteen minutes' examination of a dentist's operating equipment should satisfy any one as to his standing as an operator. Our instruments are of such importance to us that they deserve much of our attention in selection, arrange- ment and keeping in order. An instrument is divided into handle, shank, blade and cutting edge. (Fig. 115.) The handle is that part which is grasped while the instrument is being used. The shank is that part connecting the handle with the working point or cutting edge. The working point or cutting edge is that part of the in- strument which comes in contact with the material worked upon. If the working point be fiat and sharp the portion widened to bring out this form is called the blade. For convenience of communication instruments are classi- fied as excavators, pluggers, scalers, trimmers, separators, polishers, clamps, burs, drills, burnishers, etc. These names denote the purpose or the use of the instrument. If we wish to further describe an instrument we say "hatchet" or "spoon" excavator, "right angle," "contra angle," or "cow horn" plugger. These refer to the form of blade or shank. Chisels which are used for cutting or chipping away enamel have their cutting edges at right angles to the shaft and are sharpened by cutting or grinding only one plane of the blade. Hoes have the cutting edge at right angles to the shaft but the shank is so bent that the edge is looking towards the opposite end of the shaft, and the bevel to form the cutting edge is at the expense of that part of the blade away from the handle. They are used only with a drawing motion. Hatchets have the cutting edge parallel with the long axis of the shaft and the cutting edge is formed by cutting or grind- ing both planes of the blade. The shanks are made at various angles to bring the edge within reach of the cavity walls. Spoons are really not spoons in the true sense of the word. ^^^ At one time they were made that they would dip up fluid but they are not now so made. There is no concavity in the blade. They have shanks of various curves to make the blades reach into the '/J i84 PREPARATION OF CAVITIES FOR FILLINGS. various depths of cavities. Spoons are, with the chisel, the most use- ful instruments in our equipment. They will remove softened decay to best advantage and will also cut decalcified dentin. There are gingival margin trimmers and side instruments which are modifications of the chisel with shanks formed so as to bring the working edge into positions where the ordinary chisel will not reach. \l •^ Figs. ii6. 119, 122. 123. 124. 125. Figs. 128. 129 130. 131 135- 136. While it is desirable to have every form and variety of instrument that will assist in any way in operating, it is at the same time desirable to have as few mstruments as will fulfil the requirements. It will be found that the most useful instruments for all cavities in molars and bicuspids will be chisels, spoons and burs, while incisors will demand the small hatchets in addition. Below is an equipment of cutting instruments suflEicient to begin with and to fill most requirements. (Figs. 116 to 140.) BURS. THE DENTAL ENGINE. 185 The dental engine is classified as an instrument used in the prepa- ration of cavities. While it may not be used to any extent in the preparation of a given cavity yet it is indispensable to the up-to-date operator. Other things being equal the operator who uses the dental engine the least will please his patients the most. The dental engine should only be used for that part of the preparation of a cavity which cannot be conveniently done by hand. If such a rule were followed in practice patients would not dread dental operations. There are two general forms of engines which affect operations to a marked extent, the all cord engine and the flexible cable. The all cord engine carries the bur forward without any jar or shock, while the flexible cable usually winds up or springs back as pressure is brought upon the instrument, thus the bur is rotated with a series of stops and rapid turnings which jar the tooth and unnerve the patient. The all cord engine is not so convenient to reach diflfiicult locations hence its want of popularity. 142. 143- 144. 145- BURS. Only small burs should be used in the cable engine; those more than one and a half millimeters in diameter should not be used in teeth with living pulps or those with a sensitive peridental membrane. There are many forms of burs and drills used in cavity formation but the most useful is the inverted cone. (Fig. 141.) The round bur which has been used so extensively has no place in cutting that part of the cavity where a bur is indispensable. A bur should never be used to remove softened decay because spoon excavators will do it better. The round bur and the cone bur are useful to open into a pulp chamber when the pulp has been desensitized or devitalized. (See Figs. 142 and 143.) The form of the blades of a bur has something to do with the rapidity of its cutting. The dentate bur cuts enamel more rapidly than the plain blade. There is a dentate pear-shaped bur that cuts enamel better than any other form. (Fig. i44-) i86 PREPARATION OF CAVITIES FOR FILLINGS. The inverted cone bur has the great advantage of being capable of being made into other forms which are as useful as the original. Burs cannot be sharpened to make it pay at present prices but the operator can in a moment convert a dull bur into a most useful instru- ment for cutting out fissures or drilling out old fillings. A bur which has once cut enamel should never again be used to cut sensitive dentin. It has lost its keen edge. Burs should be arranged in the bur rack as new ones, those used on dentin a few times, those used on enamel and those only useful to grind into drills, etc. Dull fissure burs can be flattened on opposite sides and the end sharpened into a drill point. (Fig. 146.) Dull inverted cone burs may be ground square across the end, thus cutting the blades off the end and bringing them far enough up the shaft to be sharp. This instrument will often cut out fissures as well as the original bur. It can be ground in this way until the blades are all ground off. (Fig. 147.) The old inverted cone may be ground into wedge or hatchet shape at the end (Fig. 148) and used to open up fissures, but such an in- strument unless small gives the tooth quite a shock. It cuts better if the hand-piece is given a swaying motion. SHARPENING OF INSTRUMENTS. No instrument which is intended to cut sensitive dentin should be used until it is first sharpened. Because a hatchet is new, it is no guarantee that it is sharp though it is likely to be. An Arkansas stone, on account of being fine and hard, is the most suitable for sharpen ing dental cutting instruments. If the stone is soft the fine instrument will sink into it, cutting it into gutters, or will catch and spoil the cutting edge. The stone should be wiped off with an oiled rag and thus kept free from particles of steel. After spoon excavators have been sharpened for some time on the Arkansas stone they develop what is called a thick edge and should be ground thin on a carborundum wheel, care being taken not to heat so fine a point while grinding it. The first attempts at sharpening chisels and hatchets may result in improper bevels, but some attention to this point will avoid the difl&- culty. A free back and forth movement of the hand will ensure best results. Spoons are the most difficult to sharpen. The motion should Figs. 146. 147. 148. PREPARATION OF PIT AND FISSURE CAVITIES. 187 be back and forth on the stone, keeping the cutting edge parallel with the motion, and during each stroke the instrument is rotated so that every part of the edge will come against the stone during the motion. PREPARATION OF PIT AND FISSURE CAVITIES. General Conditions. — Pit and fissure cavities are the result of defects in the enamel covering of the tooth, and are to be found in the occlusal surfaces of bicuspids and molars, lingual surfaces of incisors and occasionally in the occlusal third of the buccal surfaces of molars. The enamel begins to calcify at several points, the central incisor at three points, the bicuspids and molars at the tips of the cusps. As the calcific matter is deposited the different lobes of enamel should join between the cusps, but this does not always happen, and as a con- sequence there is left a fissure which is a defect in the continuity of the surface and must be distinguished from a groove which is only a depression and not a defect. In teeth with very high cusps the fissures are often quite wide open. In fact they are sometimes so open in lower first molars that a fine exploror can be forced between the plates at almost any position along the depression between the cusps. It is a peculiar thing that often even such a wide fissure will not be the seat of caries while others of less width will decay. But the great major- ity of all fissures are the seat of caries sooner or later. The conditions are the most favorable for development of micro-organisms. Suitable material to develop upon is squeezed into these crevices during a meal and remains there only to be supplemented at intervals. If it were not for the pits and fissures in teeth caries would rarely occur in occlusal surfaces, because they would be kept clean by the mastication of food. There is no better cleaner of the surfaces of the teeth than the chewing of hard tough foods. Decay in pits and fissures is so often of a penetrating character that great care in examination is necessary. Even though a fine explorer will not enter between the plates of enamel there may be a large cavity beneath. In fact pulps are often reached by decay and pain be the first evidence that anything is wrong without any perceptible break in the enamel. In such cases a close observation will reveal a whitened area beneath the enamel along the fissure. Any change in the color of the enamel usually indicates some defect in the dentin beneath. If decay has once begun in a fissure there is only one treatment open to the operator. Cut it out in its entirety and include it in the cavity. Occasionally fissures may be found in recently erupted molars which have not begun to decay and may be prevented from doing so by drying l88 PREPARATION OF CAVITIES FOR FILLINGS. them perfectly and squeezing them full of soft cement carried to place on the index finger and held there until the cement hardens. This treatment will often prevent such fissures from decaying in young patients where no other measures are available. If every operator had the opportunity of seeing the micro-organisms of decay under a microscope and then seeing the width of the finest fissure under the same power there would be no doubt in his mind as to what should be done. Fissures are defects and are always a source of weakness and especially so when radiating from a cavity. Decay having once occurred in a fissure is an indication that it is susceptible, and even if the decay be all removed recurrence is almost certain if the fissures are not cut out to the end and included in the cavity. Besides cutting out the fissures it is necessary to cut out angular grooves because it is impossible to properly finish a filling flush with the margin in these deep V-shaped spaces. If they are left they only form places for the lodgment of fruit seeds, etc. Technique. — The first step in the preparation of pit cavities such as are found on the buccal surfaces of the first molars and the lingual surfaces of the upper incisors is to get access to the cavity. Since these cavities do not need their outlines increased to prevent further de- cay their preparation is quite simple. If the decay has not progressed to any extent they may be opened with a drill or a cone bur. Once a small bur will enter it is well to cut outwards rather than from with- out inwards. A larger and larger bur is used until free access is gained to the cavity. Usually there is not much soft decay in the cavity now under consideration so the inverted cone bur may be used to complete the preparation of the cavity. But if the pit has been the starting point of quite a large cavity the enamel can best be cut away with a chisel, the softened decay removed with spoon excavators and the cavity washed out with a stream of tepid water. If the rubber dam be now applied a full view of the cavity is possible and a decision as to the location of the outline arrived at. The enamel walls may be cut back with a good sized fissure bur, and the remainder of the decay removed with spoon excavators and a cement base inserted which will become the axial wall of the cavity. As the enamel rods around such cavities tend to lean towards the pit no bevel is required if the walls of the cavity are cut at right angles to the general plane of the enamel surrounding the cavity. Occasionally a cavity in the lingual surface of the upper central or lateral may have a fissure extending frorn it quite through the singu- ium which complicates its preparation. The fissure usually runs PREPARATION OF PIT AND FISSURE CAVITIES. 189 clear to the limits of the enamel which in a young patient will be far under the gum. Such fissures must be cut out and included in the cavity. It may be necessary to pack the gum out of the way with gutta-percha. An inverted cone bur will cut out such a fissure more rapidly than any other instrument. Size ^ to f mm. A groove often extends occlusally from a pit cavity in the buccal surface of a molar but rarely needs to be extended over the ridge. If an occlusal cavity also exists it should be prepared before the buccal cavity is filled because when the two cavities are open at the same time a better judgment can be formed as to whether they should be joined or not. The order of procedure in preparing fissure and pit cavities in the occlusal surfaces of bicuspids and molars is dependent upon the extent of the decay. If a shallow cavity has occurred in the central fossa of a molar w^hich has fissures radiating from it the edges of un- supported enamel may be broken down with a chisel and the outline form proceeded with at once. The fissures can be cut out with small inverted cone burs or those made into drills as described in a previous section. Once a small channel has been cut through a fissure the edges may be then broken down with a sharp chisel until the general outline has been obtained. An inverted cone bur or a sharp flat-ended fissure bur will cut out a flat seat and give the walls the proper form. If the cavity walls do not come close to the cusps the enamel wall needs no bevel. All that is necessary is to cut the walls at right angles to the pulpal wall. If there is now any decay left it may be removed with spoon excavators. If the pulpal wall has been cut with an inverted cone bur it will not be necessary to cut convenience angles nor will it be necessary to provide for any further retention than that cut with the inverted cone bur in forming the seat and walls. Clear the cavity of cuttings and it is ready to fill. If a deep cavity has occurred, however, the operator is concerned with the possibility of the involvement of the pulp and the sensitiveness of the tissues from both decay and exposure to changes of temperature. It is necessary to determine the condition of the pulp as soon as possible because if it must be devitalized it should be done before there is any cutting of sensitive dentin in gaining the outline form. Cut away the unsupported enamel with a chisel, putting the guard finger on the tooth to be cut. Then remove the softened tissue with large spoon excavators, having a care for pressure. The spoon may be worked under the leathery decay at the edges and flake after flake removed without pain. Then wash out with tepid water. As soon as it is 190 PREPARATION OF CAVITIES FOR FILLINGS. determined that the pulp is not to be devitalized there are two methods open, one is to now flood the remaining decay in the cavity with an anodyne which will prevent any pain from exposure and proceed with the outline form. Then remove the remaining decay and cover the pulpal wall with cement. In this method the deep sensitive tissues are not ex- posed for any length of time. The other method is to immediately deal with the deep parts of the cavity covering with cement and as soon as this hardens proceed with the outline form. By the latter method the sensitive tissues are dealt with early in the operation and are pro- tected from thermal changes and the seat for the filling may be cut in the cement while the fissures are being drilled out. There is always a chance of finding some decay under the edge of the cement when the fissures are cut out. The final step in either method is to bevel the enamel walls which may be done with a round bur run rapidly or a fissure bur in the right angle held perpendicular to the pulpal wall and then in such locations as come close to the cusps the instrument should be held so as to give the wall a slight bevel. A cavity in either of the occlusal pits of the upper bicuspids should Fig. 149 Fig. 150. Fig. i:;i. Fig 152. Fig. 153. when completed include both pits and the connecting fissure or groove. It is very rare indeed that the tissue between these pits should be left if either have failed. It is not necessary to cut this fissure or groove more than one to one and a half mm. in width (Fig. 149). Cavities in the occlusal surface of the lower bicuspids need not be treated in the same way. In the majority of cases there is neither a fissure nor a groove joining the pits but a ridge of sound enamel, which should be rarely cut across because defects have occurred in either or both pits, unless, of course, the enamel has been undermined by caries. (Fig. 1 50.) There is a crescentic form of the lower second bicuspid which if de- fective at all should be cut out in its entirety. (Fig. 151). Occlusal cavities in the pits and fissures of the upper molars depend in their outline form entirely upon the extent and direction of the fissures and angular grooves. A cavity in the central fossa of the upper first or second molar is usually simple in preparation. There is often a ques- tion, however, as to how far to cut out grooves extending to the mesial SMOOTH SURFACE CAVITIES. 191 or to the buccal. The general rule applies, cut all fissures and grooves until a good finishing margin can be obtained. Often it is advisable to cut the buccal groove out until the break is reached to form the buccal surface. In such cases the extremity of the groove should be sloped into the center of the cavity giving a decided bevel to the wall. Thus a good finishing margin is reached without cutting a slot clear through to the buccal surface which would tend to weaken the cusps.''' Where there is a defect in both the central fossa and the disto-lingual groove it is always advisable to prepare both cavities at the same time when a decision can be made as to the advisability of cutting across the trans- verse ridge. If cut across it should appear as Fig. 152. If there is any thickness of dentin under the ridge it should not be cut across. (Fig. 153.) There is often a supplemental cusp in the upper first molar which has grooves and fissures about it which must be cut out. These are often so penetrating that cusps are undermined and must be cut away thus facing almost the whole occlusal surface with the filling. (Fig. 154.) Fig. 154. Fig. 155. Fig. 1^6. Fig. 157. Third molars are irregular in their markings but usually have three cusps, two buccal and one lingual, with a pit between and fissures run- ning buccally, mesio-lingually and disto-lingually. Neither fissures nor grooves pass over the marginal ridges. (Fig. 155.) Lower first molars have a central depression which is often defective and fissures and grooves extending buccally, lingually, mesially, and distally. These cavities are the most uniform of any under this head- ing. (Fig. 156.) The lower third molars often have the same outline as the lower first, while the second will have the appearance of Fig. 157. SMOOTH SURFACE CAVITIES. I. Cavities in the gingival third of labial, buccal and lingual surfaces. General Considerations. — The number of cavities and the extent of caries in these locations is a true index to the care of the teeth. Cavi- ties should not occur in these locations if our present views of the 192 PREPARATION OF CAVITIES FOR FILLINGS. cause of caries be correct, that is if the patient takes reasonable care of his teeth. There is not a buccal or lingual surface except in cases of marked irregularity that cannot be reached with a tooth brush. It is safe to say to the patient who has such cavities that he does not brush his teeth properly and a lesson should be given to him at once. In the majority of these cases the first indication of beginning caries is a sensitive spot that the patient accidentally finds with his finger nail or a tooth pick. The area of the sensitiveness gradually increases until the tooth brush is not used even on that side of the mouth for fear of touching the sensitive spot. A break in the enamel occurs and extends both mesially and distally. This line is just at the junction of the free margin of the gum with the enamel where there is a slight protection from the action of the lips. These white lines of superficial decay rarely enter the proximal surface in young patients but usually do so in those of advanced years where the gums have receded to some extent. This decay never begins under the free margin of the gums but often extends there by undermining the enamel. In such cases the sharp edge of the cavity irritates the gum tissue, causing a hypertrophy which makes it appear as if caries had begun under the gum. The proper treatment of labial, buccal, and lingual caries calls for careful consideration, not that fillings are often dislodged but that they so often fail at the margins. There is usually an area of defective enamel extending from the cavity and unless this is all cut out failure is certain and even then the operation has not changed the environ- ment. The future of fillings in these locations depends more upon the patient than upon the perfection of the operation. If after these loca- tions on the teeth have been made comfortable the patient cannot be induced to regularly and carefully clean them no kind of operation other than the removal of the gingival third of the affected surface and covering the gingival margin with healthy gum tissue will last even a reasonable time. It is often a serious question how much of the enamel about such defects should be cut out and included in the cavity. The indication of the beginning of caries is a sensitive area. In such cases a thorough polishing with powdered pumice followed by chalk, with instructions to the patient to follow a simular treatment will often prevent the formation of a cavity. Since the general introduction of porcelain as a filling material labial cavities may be more freely cut for the prevention of future caries. Though many labial, buccal and lingual cavities are difficult to manage there are a few where decay is slow and the tissue so non-sen- SMOOTH SURFACE CAVITIES. 1 93 sitive that they are among the simplest operations that come under the dentist's care. Technique. — The form to be given these cavities is simple but the management of the operation is exceptionally difficult, be- cause of the hypersensitiveness of the dentin and even the enamel, and because of the difficulty of getting free access to the cavity. The gum tissue has usually grown into the cavity and is exceptionally sen- sitive as all pathological gum tissue is. And perhaps the greatest handicap of all is, the patient dreads the operation more than all others and the operator dreads it himself. Operations in these locations have a peculiar tendency to increase the flow of saliva which adds materially to the difficulty of the operation and to the discomfort of the patient. There are few operations in dentistry where the pain and discomfort to the patient are so out of control of the operator as a shallow sensitive cavity in the buccal surface of a lower molar in a nervous woman. The saliva flows freely, the ordinary therapeutic remedies cannot be used unless the rubber is applied and this cannot be done without a clamp which will certainly touch the sensitive area. Difficulties such as these can only be overcome by an experienced mas- ter hand. The hypodermic injection of novocain and adrenalin chloride into the gum opposite the end of the root promises results, while the injection of cocaine into the tooth with the high pressure syringe is more to be depended upon. In the majority of small cavities even if the gum tissue has grown into them it is less painful and more expeditious not to make any at- tempt to remove the gum from the cavity until the operation can be made, while in large and deep cavities where cotton and gutta- percha can be packed and retained without the removal of much of the decay it is wise to do so at a previous sitting. When the gum is re- moved from these deep cavities one of the difficulties has been over- come. In labial cavities the first step after using a solution of cocaine on the gum around the neck of the tooth is to apply the rubber dam. Dry the cavity. Break down the enamel around the cavity avoiding the decalcified dentin. Carefully plan the next step which will be the most important in the preparation of all such cavities. It is just as painful to remove one layer of the decalcified tissue as it is to remove the whole mass. If the cavity be small and no danger of pressing upon the pulp, select a location at the mesial or distal wall and sink a sharp hatchet or Darby-Perry spoon No. 9 or 10 down to the bottom of the decay and scoop the whole mass out at once. Just as this cut is undertaken the operator should warn his patient and at the same time divert his 13 194 PREPARATION OF CAVITIES FOR FILLINGS. attention by remarks on some interesting topic. An application of hot phenol or phenol and alcohol will relieve the pain incident to the exposure of the dentin to the air. The further preparation of the cav- ity will not be more sensitive than any other unless it should reach the junction of the proximal surface with the labial about one mm. from the gum. An inverted cone bur in the direct hand-piece will cut a flat axial wall, and extend the other walls in any direction leaving sufficient undercut to start and retain the filling. Since the introduction of por- celain it is not necessary to discuss the peculiar forms of these cavities which make gold fillings the least conspicuous. The outline should extend under the free margin of the gum and when finished be covered with it. There should be such extension mesially and distally as will ensure sound, hard enamel. If any special convenience is required to start a gold filling it should be cut in that part of the cavity furthest from the operator and in the greatest thickness of dentin. Any un- dercuts in the dentin for retentive purposes should be in opposite walls of the cavity. The cavo-surface angle may be trimmed with a chisel or a round bur or a cone bur. The r-e- maining decay over the axial wall, if any, Fig I 8 Fig" 159. should be removed and the cavity is pre- pared for filling. (Figs. 158 and 159.) Buccal cavities in bicuspids are treated in like manners but those in molars are modified by the difficulty of access and the impossibility of applying the rubber dam when the gingival wall is far below the gum. The decay may be removed in the same way and the final forming of the cavity done with a bur in the right angle. There is one frequently occurring buccal cavity which nearly always fails when filled. It occurs in the distal third of the buccal surfaces of third molars. These surfaces are rarely cleaned by either food or the tooth brush. Sooner or later they involve the whole disto-buccal surface and the occlusal. While they are small cavities in the buccal surface they are so sensitive and difficult of access that proper extension cannot be made, hence recurrence of caries is inevitable. As soon as the occlusal surface is involved a good dovetail can be cut and the filling when inserted sloped off in such a manner as to prevent heavy occlu- sion upon it. Lingual cavities in the gingival third are rare. They only occur because of a marked recession of the gums or from wearing an artificial denture. The preparation of the cavity is similar to that in the labial and buccal surfaces. Any variation will depend upon the extent and location of the caries. SMOOTH SURFACE CAVITIES. I95 2. The preparation 0} cavities in proximal surfaces 0} incisors and cuspids which do not involve the incisal angle. General Considerations. — Patients who have neglected their teeth for years take an anxious interest in them as soon as cavities appear in their incisors and cuspids. They recognize at once that if these teeth become unsightly they have lost one mark of beauty. They often allow molars and bicuspids to decay beyond any hope of being restored to usefulness under the foolish notion that they can re- tain the anterior teeth even if the others are lost. There is no more fallacious notion than this met with in the practice of dentistry, except perhaps mistaking the first permanent molar for a deciduous tooth. It is dijQ&cult to decide what is best to do for a patient of say twenty- eight years of age who has lost the power of mastication on his molars and bicuspids and has several proximal cavities in the incisors. The incisors are used for a purpose for which they were never intended, and as a consequence wear down rapidly, cutting off the incisal reten- tion to proximal fillings. While it is true that a patient is justified in becoming anxious when his anterior teeth begin to decay he should in fact be more anxious when his molars and bicuspids show signs of being lost, because the anterior teeth cannot be preserved permanently if they are used for the mastication of food. Artificial dentures of molars and bicuspids alone are but a poor substitute for the natural teeth of mastication. The incisors will be used in preference, to their destruction. It is the dentist's duty when he sees small proximal cavities in the anterior teeth to look into the future sufficiently to edu- cate his patient along the lines of being exceedingly anxious about the condition of the molars and bicuspids. Fillings in the anterior teeth even if small are doomed if they are called upon to bear the stress of mastication. These teeth are thin and small and give but a poor oppor- tunity for the firm anchorage of fillings and if called upon to do a duty they were not intended for there is certain to be failure. This is the cause of a large class of failures in fillings in the anterior teeth which cannot be classed among failures from recurrence of caries. It has been found by those of largest experience in filling teeth that there are certain areas of the teeth more susceptible to caries than others. These susceptible areas are found to be those which are not habitually cleaned by excursions of food in mastication, or by the friction of the cheeks, lips, or tongue. Proximal surfaces of the anterior teeth which are close together are not habitually clean, and decay in propor- tion to their uncleanness. It has also been observed that not all points of proximal surfaces are equally susceptible. All that portion from the 196 PREPARATION OF CAVITIES FOR FILLINGS. incisal edge to the contact point is usually immune and in fact the actual contact point is rarely the scat of beginning caries but a point immediately gingival to the contact is the susceptible area. This is as it were an eddy behind the contact where secretions may rest and plaques form without disturbance. Each case presents its own little variations and should be considered before any operating is proceeded with, because in these days of esthetics the whole susceptible area may sometimes be removed and restored with gold without exposing the filling. It has been noticed for a long time that proximal gold fillings fail at the gingival margin, which is true, but closer observation has shown that failure rarely occurs in the center of the proximal surface but at the linguo-gingival angle and the labio-gingival angle. That portion of the gingival margin in the center is usually covered with gum tissue and hence does not decay, while both to the lingual and to the labial of this point the free margin of the gum crosses the margin of the filling and at these points recurrence happens. If the margin is placed im- mediately gingival to the contact it is in a susceptible area and failure is imminent. Teeth which are spaced in the occlusal or incisal third will have their proximal surfaces cleaned by the excursions of food down to the contact and if the margin of the filling is incisal to the contact re- currence is unlikely. The lingual margin is often a location of failure of proximal gold fillings in the anterior teeth. Operators have too frequently left the lingual enamel plate for the convenience of packing the gold. Cavities are often cut quite over on the labial surface for convenience of access. Such preparations are a mark of the man who is compelled to do too many fillings a day to make a competence. There is often a marked concavity both inciso-gingivally and mesio-distally on the lingual sur- face of an incisor which leaves the lingual wall little more than enamel if a proximal cavity occurs. If such a lingual plate of enamel is left it is not strong enough to bear the stress of packing gold against it without fracture. Even if this enamel plate does not actually break out during the insertion of the gold it becomes checked sufficiently to allow leakage. There is only one safe rule to follow. Cut the enamel away on the lingual, until what remains is supported by dentin. The preparation of small proximal cavities in the anterior teeth naturally divides itself into two general classes. Those which are pre- pared with a view to the permanency of the filling and those which are prepared knowing that the filling will be more or less temporary. If all the work of the dentist could be made mechanically correct and its permanency was not dependent upon conditions outside of his control, SMOOTH SURFACE CAVITIES. I97 dentistry would be practised as a trade and would not have the power to retain so many bright minds within its ranks. The varying circum- stances that influence the permanency of dental operations make dentis- try interesting. The only man who can say that his operations will be permanent is the one who does not know or the one who intentionally wishes to deceive. The claim of absolute permanency of dental opera- tions has done much to discredit the profession because the patient who has lost several so-called permanent fillings must think that the dentist was ignorant or dishonest, either of which is not creditable to the profession. Therefore when we speak of preparations for so-called permanent fillings w^e mean only relatively permanent. Porcelain fillings have within the past few years taken such a hold on the profession that few gold fillings are now inserted in exposed sur- faces of the anterior teeth for patients who value their personal ap- pearance. Though this may be true there is still a large field left for gold and other fillings. The preparation of cavities for those fillings which may be looked upon as more or less permanent demands a study of the general con- dition of the patient, the oral secretions, the mucous membranes and the teeth. There must be a careful study of the susceptible and im- mune areas of the teeth. These considerations will usually demand the extending of the gingival wall of proximal cavities under the free margin of the gum and the labial and lingual w^alls to those areas which are immune to caries, while the incisal margin will be carried far enough to the incisal to prevent it from coming in contact with the adjoining tooth. If a cavity is so extended there will be no portion of its margin in susceptible areas. The gingival margin will be covered by healthy gum tissue, the labial margin will always be kept clean by foods, the lips, and the brush, the lingual margin by food and the tongue, and the incisal margin by food. The only other requisites for a fairly permanent filling will be perfect mechanical adaptation to the cavity walls and not so much stress of occlusion as will wear, stretch, or dislodge the filling. The preparation of cavities in proximal surfaces of incisors which must of necessity be looked upon as temporary demand less general consideration but more consideration of the particular reasons for such temporary operations. There must be a perfect understanding between patient and operator when operations are to be made which are not ideal. The ideal operation may be pointed out to the patient and the reasons given for deviations from it. In this way the patient understands what is to be expected from such operations and is not 198 PREPARATION OF CAVITIES FOR FILLINGS. deceived. And besides if the operator shows himself to be a good prog- nosticator his standing is enhanced in the patient's mind and not di- minished if the operation lasts no longer than he said. While we must admit that all cavities cannot be prepared according to an ideal formula there is no intention in this chapter to countenance slip-shod operating. Every reason that may be given here for not pre- paring cavities according to the outline in a previous paragraph can be made an excuse for careless operating. One operator may be so much more skillful and deft about his work, that what would be too painful for another operator's patient to bear would be easily borne by his. The rough, unskillful operator will rarely find patients who can bear to have proper preparations made in teeth with living pulps, while the skillful operator will rarely find cases where perfect prepara- tions cannot be made. If the proper preparation of a cavity would prove too painful for a young patient a temporary operation is indicated, and in such a case where cement is to be used, it is not desirable to break down any more of the enamel than will ensure sufficient access to remove the decay. Then again if small proximal cavities develop slowly and the ex- posure of gold would be objectionable it would be manifestly better to gain sufficient space to insert small gold fillings than make the ideal extensions. Such small fillings are not likely to prevent further decay for more than three or four years but the patient has not had gold fillings exposed in the teeth for that much of her life. While it is sometimes desirable to make cavities that do not have their margins in immune areas there are certain cases which are so markedly susceptible to caries that they must have their margins carried full well on to immune areas. Technique. — Separation is a necessity for the proper preparation and filling of proximal cavities in the incisors and cuspids. Space should be gained in such a way as to prevent the teeth from being sore when worked upon. There is no necessity for having the peridental membrane so sensitive that the patient experiences pain from every touch of the tooth. If slight soreness should occur it is well to support the teeth while operating. Usually the first step in the preparation of proximal cavities in incisors is to chip away the thin enamel with a chisel or a hatchet or hoe excavator. These latter instruments are narrow in the blade and unless carefully used the points may drop into the sensitive por- tions of the cavity. The thin edges of the cavity may be shaved down from the incisal to the gingival on the labial and the lingual with the SMOOTH SURFACE CAVITIES. 1 99 corner of a triangular chisel, holding the second finger on the tooth as a guard. The blade of the chisel should be carried toward the center of the tooth as the edge is carried toward the gingival. A sharp spoon will remove the major portion of the decay. At this time a decision can be made as to the extent of the carious tissue and the probable outline form. The outline form having been decided upon, the chisel with a keen edge will do more than any other instrument. The enamel may be cut away chip by chip until the incisal margin reaches a point which will be kept clean by excursions of food. Both the labial and the lin- gual walls may be cut back with the chisel, using the pen grasp, but occasionally the thumb and palm grasp will reach the lingual walls to best advantage. In opening up the cavity the loose decay was re- moved, also the thin enamel edges, so now the chief concern is with the proper formation of the cavity for the reception of the filling and the pre- vention of future decay without regard to existing caries. Cavities of less than 1.5 mm. in diameter without much undermining of the enamel can be extended to advantage with a round bur. The largest round bur which will enter the cavity is not so likely to cut into the dentin and cause pain. The blades may be carried against the enamel cut- ting from the dentin outwards. It will be found necessary to extend the gingival wall considerably rootwards in many cases to insure the margin of the cavity being covered with healthy gum tissue. In the case of the small cavity just mentioned a round bur directed against this wall in the manner described will work quite efficiently. But in the majority of cases an inverted cone bur h mm. in diameter for laterals and small cavities, and i mm. in diameter for centrals directed against the gingival wall and swept across from labial to lingual and from Ungual to labial holding the hand-piece at such an angle as will give the corner of the bur a grip of the tissue will usually cut the dentin gingivally and at the same time make a flat seat for the filling with convenience angles for starting the gold both at the linguo-gingivo-axial angle and the labio-gingivo-axial angle. As the bur cuts into the angles the hand-piece should be swayed in an opposite direction and the bur carried upward along the labio-axial line angle and linguo-axial line angle, thus making a slight groove which should under no cir- cumstances extend more than one-third or one-quarter of the distance to the incisal retention. In this connection it must not be under- stood that grooves are recommended in either the labial or lingual walls. A slight extension incisally from the convenience angles for holding the filling more securely during its insertion is all that is desirable. As 200 PREPARATION OF CAVITIES FOR FILLINGS. the gingival wall is thus formed the enamel edge will not be cut away which can be done with a narrow chisel introduced from the labial. Such a chisel should have a fine neck so it may be held at any angle. A round bur may be used to trim the enamel at the gingival but must be held firmly, allowing it to rotate in the proper direction, or it may catch on the edge and pull the rubber off or cut a deep notch in the margin. The outline at the junction of the lingual wall with the gingival and the labial with the gingival must be cut with great care otherwise too much bevel will occur, or these points will not be ex- tended far enough to ensure a clearing margin. It must be kept in mind that these are vulnerable points in these fillings. Any decay or decalcified tissue that might be remaining in the cavity should be removed. Spoon excavators with thin cutting blades and of a size to readily enter the cavity will rapidly remove the remain- ing defective tissue. Darby-Perry No. 9, 10, 2 and 4 are thin bladed spoons suitable for small cavities. Give the cavity proper form to resist any stress that may come upon the filling, also make it of such a form that it will be convenient to fill. In cases where the gingival wall does not need extension for pre- vention, and the outline form has been obtained and the decay re- moved, the resistance form, the retentive form and the convenience form may be all made at the same time. An inverted cone bur ^ mm. in diameter for small cavities and f or i mm. in diameter for larger cavi- ties in centrals and cuspids will cut a flat seat at the gingival by holding the instrument parallel with the long axis of the tooth and carrying it well into the linguo-gingivo-axial angle and into the labio-gingivo- axial angle as before mentioned. In these cavities it is impossible to cut the gingival wall at right angles to the long axis of the tooth with an inverted cone bur because the shaft cannot be held exactly parallel with the long axis, but if the dentin be cut slightly deeper at the gingivo- axial line angle the outer border or enamel wall may then be trimmed sloping inward except at the cavo-surface angle which should be beveled. The main feature of the gingival wall is to be flat from labial to lingual and form a right angle or an acute angle with the axial wall. There should be no deep grooving of the gingival wall nor cutting of deep pits. A flat seat with walls forming right angles from it is the best form to resist stress. The necessary retentive form in these cavities is provided for in the cut into the linguo-gingivo-axial angle and the labio- gingivo-axial angle and a slight cut into the dentin at the junction of the lingual wall with the labial at the incisal extremity of the cavity. At these points the dentin is the thickest and the cuts are directed away SMOOTH SURFACE CAVITIES. 20I from the pulp. The incisal retention can be completed with an acute angled hatchet, S, S. W., No. 27. This instrument may start to cut at the labio-axial line angle about a milhmeter from the incisal retention and be carried toward the incisal and then started again in a similar position on the lingual carrying each cut around the incisal retention started with the bur. This action of the instrument will deepen the cavity rapidly. It is not necessary to make a deep undercut at this point, it is more important to have a good bulk of gold even at right angles to the axial wall than a fine hole bored deeply. The lingual wall should not under any circumstances be grooved in its length nor should the labial. There are cases where a short groove may be extended from the convenience angles but even these are not necessary in small cavities. A source of weakness in fillings at the incisal margin is the thinness of the gold. The enamel rods on distal surfaces have a decided incline towards the incisal, and if beveled at all makes the gold thin. This Fig. 160. Fig. 161 Fig. 162. Fig. 163. difficulty may be overcome if the incisal retention is some distance gingival to the cavo-surface angle by making a slight concavity from the incisal retention to the cavo-surface angle with a round bur. This deepening between the labial and lingual cavo-surface angles will thicken the gold to the very edge. Such a concavity cannot be cut deep or the retention might be destroyed and the enamel plates under- mined. (Figs. 160, 161, 162, 163.) The enamel wall may be trimmed and beveled with the chisel, round bur or strip, and where there is abundance of space the disk. The disk and strip are very treacherous instruments but in the hands of those who are willing to study their peculiarities are the most tract- able at our command. A strip narrower than the inciso-gingival di- ameter of the cavity held tight and carried back and forth without pressure against the walls will finish an enamel wall in these cavities as no other instrument can. A disk in large cavities may be satis- factory but it should not be permitted to reach the junction of the gingival wall with the labial or lingual or too much bevel will be the result. A round bur is better adapted for these positions. 202 PREPARATION OF CAVITIES FOR FILLINGS. If the cuttings are now removed from the cavity and the tissue over the pulp carefully inspected the filling may be inserted. Lower incisors and cuspid cavities demand special treatment in so far as these teeth differ in form from the uppers. They have smaller and longer crowns than the uppers. They are much narrower mesio-distally and the contact points are always at the incisal edges. The latter fact together with concave proximal surfaces at the gum line make operations prone to failure. The teeth are so thin that the labial and lingual plates of enamel have but little dentin between them, and if retention be cut deeply between these plates for the incisal reten- tion the corner is almost certain to fracture. In some of these teeth the pulp extends far into the crown and is a source of difficulty. Cavities which do not extend close to the incisal edge are simple in prepa- ration and the fillings of fair permanency. There is little or no stress on small fillings in the lower anterior teeth. Retentive form is made as in the upper. In fact the preparation is the same except that there is not as much space between the teeth, and all the instruments should be smaller. Retentive form and convenience angles may be cut with a J mm. inverted cone bur holding the shaft at right angles to the long axis of the tooth. The base of the bur may be carried down the lingual wall and sunk into the gingival at the linguo-gingivo-axial angle. The labio-gingivo-axial angle may be cut in like manner using a bur in the right angle hand-piece. The incisal retention may be cut as in the uppers. 3. Preparation of proximal cavities in incisors and cuspids which involve the incisal angle. General Considerations. — Proximal cavities in incisors and cuspids which have become so extensive as to involve the incisal angle have usually been filled before. The conditions which caused the failure of the former filling will be of value in determining what form "of preparation is desirable for the new cavity. In such cases as have not been filled before there is often difficulty in deciding whether the incisal angle should be cut away or not. Corners of enamel often stand the force brought upon them before the filling is inserted and break off shortly afterwards. There may be two reasons for this, a tooth with a cavity in it is usually saved a little in mastication but as soon as made comfortable by a filling it receives full force upon it. Or the corner of enamel may be checked during the insertion of the gold and come away later. It is a safe practice to remove a corner of enamel when it has not a support of dentin if the cavity is to be filled with gold- As patients become older the enamel is more and SMOOTH SURFACE CAVITIES. 203 more worn away and seems to check and split more readily than thicker tissue. This is especially true where pr.oximal fillings have failed from wearing away of the tooth tissue leaving the filling to carry too much stress. The margins of cavities in such teeth demand free cutting away of tissue and careful operating to prevent checking of the edges. The character of the articulation, the peculiar motion of the teeth on each other in mastication and the force of the occlusion all influence the operator in deciding the form of preparation. In most of these extensive operations failure does not occur from primary decay about the margins, but is secondary to the shifting of the filling or checks in the enamel. If a patient should have no molars and bicuspids suitable for mastication large fillings in the incisors need to be much more firmly seated than if there were good posterior teeth for masti- cation. Teeth which come together with a kind of anterio-posterior motion, sliding the lowers from the labio-incisal angle of the uppers to the gingival will drive almost any filling from the upper teeth. And if the lower teeth happen to require fillings, they will be as likely to fail as the uppers. Outline Form. — The determination of the outline form in proxi- mal cavities which involve the incisal angle is not one of extension for prevention in the ordinary acceptation of the practice. It is extension to more securely anchor the filling rather than to prevent decay. The proximal surfaces are usually so far extended before such an operation is contemplated that no further extension is necessary to prevent recurrence of caries on these surfaces. The outline form depends on the age of the patient, the extent of the caries, the thickness of the tooth, the amount of wear on the incisal edge, the friability of the enamel and the character of the occlusion. Depending upon these conditions there are five methods of preparation open to the operator. The first to consider is a modification of the method used in preparing proximal cavities which do not involve the incisal angle. The indi- cations for this form of preparation are thin teeth, young patients, not very heavy occlusion, not much of the incisal edge involved and not much undermining of the corner. Resistance Form. — The seat and labial and lingual walls are prepared as already described, except that the seat is made broader and longer and the grooves are made deeper. The filling will be called upon to bear heavier stress than those described in the former section and requires a greater seat. The labial and lingual margins should be a straight line from the incisal to the point where they curve to form the gingival wall. 204 PREPARATION OF CAVITIES FOR FILLINGS. Retentive Form. — Much care is necessary to avoid cutting out all the dentin between the labial and the lingual enamel plates in cutting the incisal retention. To be of the most value this retention must be as near the point of stress as possible and large enough to contain a sufficient bulk of gold to have strength to resist the forces of dislodgment. The horn of the pulp is not always secure from an accident in cutting this retention. It is generally sufiEicient to make the occlusal wall of this retention at right angles to the long axis of the tooth, but to be certain of doing this it is well to aim to make the depth of the retention closer to the incisal than that at the axial wall. Technique. — With a wide chisel cut away the corner, shaving both the labial and lingual to the gingival. Some patients' only fear is the slipping of the instrument and wounding the gum or touching the sensitive portions of the cavity. In such cases a coarse disk or a thin stone will trim away the enamel corner readily and with less anxiety to the patient. Remove the softened dentin and form the seat with an inverted cone bur i mm. in di- ameter which may be held parallel with the long axis of the tooth and carried into the labio- and linguo-gingivo-axial angles, cutting deeply into the dentin at these points and P ^g F fi carrying a groove towards the incisal less than half way. The incisal retention may be cut with an inverted cone bur held at right angles to the axial wall giving thecornerof the bur a catch into the dentin some distance gingivally to the final occlusal wall. Slight grooves may now be cut toward the gingival from the incisal retention. A disk is the only instrument to finish the enamel walls. It can be held to cut the enamel parallel with the length of the rods and then to slightly bevel the outer third. The incisal cavo-surface angle will bear considerable bevel. Remove any remaining decay from the axial wall and clean up the cavity walls. (See Figs. 164 and 165.) The second method is suitable in thin teeth, young patients, incisal surface not much worn nor not much involved, corner undermined. Chiefly useful in laterals. Pits and grooves in the lingual surface may be included in such a preparation. The outline form is the same as in the last case except that there is a tongue or dovetail cut in the lingual surface at least one and a half mm. from the incisal edge depending upon the form of this sur- face. The margins of the dovetail should join with the lingual wall in rounded corners. SMOOTH SURFACE CAVITIES. 2O5 The resistance form at the gingival is the same as in the last case. The retentive form in the incisal region is entirely different. Instead of cutting between the labial and lingual plates as in the former case the incisal retention is cut into the lingual surface in the form of a dovetail. The dovetail is cut about one and a half mm. in depth, depending upon the thickness of the tooth and the nearness of the pulp. The direction depends upon whether there are defects in the enamel of the lingual surface or not. It is generally advisable to make this retention at right angles to the proximal wall and about one and a half mm. inciso-gingivally and about one and a half to two mm. mesio-distally. To be of the greatest value as retention it must be cut as near as possible to the incisal but must not be so near as to weaken the edge. Technique. — The technique up to cutting the supplementary retention in the lingual has already been described. It is always difficult to control the hand-piece to cut into the lingual surface of any Fig. 166. Fig. 167 Fig. 168 tooth and it is especially difficult to do so in this case, if it becomes necessary to use the right angle. Where this form of preparation is advisable the lingual surface is usually markedly concave inciso-gingi- vally thus making it almost impossible to reach it with the straight hand-piece. Unless the operator has confidence in his ability to hold the hand-piece and operate through the mouth mirror it is better to raise the chair, tip the patient's head back and operate by direct view. A No. ^ or I mm. inverted cone bur should be held at right angles to the lingual surface of the tooth, starting the corner of the bur on the lingual wall of the cavity at the junction of the enamel with the dentin. This bur will cut a slot the full depth of the enamel and the necessary distance towards the opposite side of the tooth. The enamel edges should be cut back and, if need be, the slot cut larger and made reten- tive in form, that is, the incisal and gingival walls must be slightly undercut. (Figs. i66, 167 and 168.) The third method of preparation is indicated in thin teeth, corner undermined, edge much involved, lingual plate of enamel badly de- cayed, and heavy occlusion and appearance of gold not a serious 2o6 PREPARATION OF CAVITIES FOR FILLINGS. objection. In such cases there is a step cut in the incisal surface, its width depending upon the extent of the destruction of the cutting edge. As a rule the step should extend mesio-distally farther than the width of the filling to be supported. The depth depends upon the weight of occlusion and the thickness of the tooth. Technique. — When it has been decided to cut across the incisal exposing the gold on the labial surface a stone is the most suitable instrument to begin with. Cut the incisal edge down the width and depth required. Prepare the proximal cavity as in case two. With an inverted cone bur cut a groove from the proximal cavity across the step between the labial and lingual enamel plates, deepening and enlarging the groove at its extremity. A good deal of care is necessary in cutting this groove to keep it from coming too close to the labial plate and at the same time have it large enough to contain sufficient gold to have strength. Fig. 169. Fig. 170. Fig. 171. The fourth method is more frequently applicable than either of the last two described. This method of preparation was first described by Dr. Johnson and takes his name. It is indicated in thick teeth, much worn, corner undermined, edge much involved, heavy occlusion, brittle enamel, old patients, lingual surface not too much involved. The successful preparation of such a cavity and filling it with gold demands much consideration before it is undertaken and careful manipulation afterwards. Technique. — The seat and proximal surface are prepared as in the last two cases. Dependence for the retention of the filling is in the step cut across the incisal. The step does not involve the labial plate and yet the occlusal surface is completely covered with gold. The step is largely at the expense of the lingual surface. The labial wall must in consequence be cut with a definite angle with the axial wall. The labial wall in the step must also meet the pulpal wall with a definite angle to give the necessary resistance to a heavy occlusion coming against the lingual surface of so large a filling. The outline from a labial view is shown in Figure 169. There is no exposure of gold except as a proximal filling. If the incisal sut- SMOOTH SURFACE CAVITIES. 207 Fig. 172. face has been sufficiently worn to expose the dentin the outline will show the whole occlusal surface faced with gold. (Fig. 170,) The lingual outline will show almost a third of the surface covered with gold. (Fig. 171.) Those surfaces of the tooth which are exposed to heavy occlusion are covered with gold and those surfaces which are exposed to view from without show but little gold. An inverted cone bur held against the axial wall at right angles to the long axis of the tooth will, if carried across the incisal, cut the step about i mm. in depth. This first cut must be kept well to the lingual or the labial plate may be so thin as to expose the gold through the enamel. The lingual plate may now be trimmed away with the chisel. Usually it is necessary to carry the inverted cone bur across the incisal again to make the step flat and at right angles to the stress. The extremity should be deepened to give additional strength and to resist tipping. The groove through the dentin forming the step should not be more than ^ mm. deeper than the lingual wall except as it approaches the extremity where it may be slightly deeper, while at the same time the lingual wall is not trimmed away so much at this point. There may in some cases be some difficulty in obtaining sufficient resistance to forces which may happen to be applied to the labial surface. But as a rule fillings are rarely tipped to the lingual. Finishing the enamel walls demands a careful study of the direction of the enamel rods at every point. The labial wall of the step may be beveled with a fissure bur, a disk or a round bur. This wall is sloped from the junction of the labio- incisal angle to the pulpal wall of the step. The extremity of the step is best trimmed with a round bur. The lingual wall of the step must have a slight bevel and join with the proximal lingual wall in a rounded form. A sharp corner at this junction would invite failure either during the insertion of the filling or after- wards by the occlusion. At the junction of the labial wall of the step with the proximal wall is a source of weak- ness if a sharp angle is left to the enamel. A small disk in the right angle will reach the lingual cavo-surface angle and also the labial. The fifth method is applicable in those cases where there is an edge to edge bite, wearing the teeth down to expose the dentin and perhaps loosening the incisal retention in a small proximal fill- FiG. 173. Fig. 174. 2o8 PREPARATION OF CAVITIES FOR FILLINGS. ing. There is not much of the incisal edge lost and yet a proximal lilling cannot be retained because of the rapid wearing of the tooth and the difficulty of cutting an incisal retention. The surest method to follow is to cut the step clear across the incisal including all the exposed dentin and beveling both the labial and lingual enamel walls toward the pulpal wall of the step. Of course, enough of these walls must be cut down to face the whole end of the tooth with gold. The prepara- tion of the proximal cavity should be done as before described except that it does not require any provision for retention because the step will provide all the resistance necessary. There is little or no force to drive the filling to the labial or the lingual because there is little loss of these surfaces. The chief point of difficulty in preparation is at the junction of the proxi- mal cavity with the step. There must be bulk enough of gold at this point to ensure against stretching. If a sharp corner is left at this junction it tends to leave a point to start the stretching of the gold. The technique of preparing this cavity is so much like those just described that it is not necessary to repeat it. (Figs. 172, 173 and 174.) Shoeing. — There is a class of cavities met with in old patients so similar to the one described in the previous paragraph that it might not be out of place to describe their preparation here. They are strictly speaking occlusal cavities but they are not similar in origin to other occlusal cavities already described. As patients advance in years their teeth become worn until the dentin is reached which soon hollows out in a cup shape on the occlusal surface. This exposed dentin often becomes quite sensitive to acids and in fact is dissolved or worn away so rapidly that the pulp is often involved. The teeth become much shortened and unsightly. To foresee and prevent such unhappy results is the duty of the dentist. If a tooth seems to be cupped out even though there is little direct antagonism of the opposing tooth, p^^ ^ ^ it is well to prepare a cavity for the reception of a gold filling which will cover the exposed dentin and prevent its further wear. The anterior teeth, both upper and lower, are chiefly subjected to such wearing because so many people have lost their molars and bicuspids. Technique. — The technique of preparation is simple. This eburnated dentin is not usually sensitive to cut. An inverted cone bur can be held parallel with the long axis of the tooth and car- ried across the occlusal surface cutting a groove about a millimeter PULPLESS INCISORS HAVING LARGE PROXIMAL CAVITIES. 209 in depth. As the tooth is worn down a good deal it is quite thick labio-lingually giving ample room for good anchorage. The extremi- ties of the groove should not come too close to the mesial or distal sur- faces. The inverted cone will make all the undercuts necessary to keep the filling from being lifted from the cavity which is the only force that can dislodge it. The walls should be sloped into the cavity and the finished filling should come over the entire end of the tooth and be of sufficient thickness to resist stretching or curling up at the edges from constant hammering of the opposing teeth. (Figs. 175 and 176.) PULPLESS INCISORS HAVING LARGE PROXIMAL CAVITIES. While the majority of incisors which have lost their pulps and have large proximal cavities require to be filled with porcelain or should be cut off and restored by a crown there are cases which should be filled with gold. The difficulty in preparing such cavities is to avoid cutting away the dentin; because so much has been already lost by getting access to remove the pulp there is no strength left to retain and support a filling. In thin teeth not much worn on the incisal, a fair amount of dentin, and not much filling exposed to occlusion the chief reten- yig m tion may be obtained in the pulp chamber. The pulp chamber should be filled with cement and then the gingival wall cut wide and flat as if the pulp had receded markedly. Grooves may be cut in the labial and lingual walls part of the distance to the in- cisal, depending upon the thickness of the tooth. The incisal reten- tion should be cut with an inverted cone bur placing it into the pulp chamber and cutting towards the incisal, thus getting a good undercut without going near the incisal. The aim should be to make up in bulk of gold (the greater portion of which will be in the pulp cham- ber) for not getting the retention as near the point of stress as in other cases. If the tooth is thin and the decay together with the cut- ting to remove the pulp has involved a good deal of dentin any further cutting of dentin is contra-indicated. It is better to depend for retention of the filling upon a post cemented in the root canal and extending far enough into Fig. 178. |-]^g cavity proper to give a good attachment for the filling. There is no further preparation of the cavity required than to give it proper outline form and resistance form; the post will provide the retention. The technique of inserting a post in an incisor so that a gold filling may be condensed around it is not always easy. Select a 14 2IO PREPARATION OF CAVITIES FOR FILLINGS. piece of iridio-platinum wire No. i6 for a central or cuspid and No. i8 for a lateral. Ream out the canal about five to seven mm. in depth, not the same diameter the full depth, as it is usually better to taper the wire slightly. To do this it is best held in a pin vise for filing. With heavy pliers give it the necessary bend to enter the canal and project in the center of the cavity so that gold may be packed between it and the cavity walls and also cover it at the surface. To accomplish this it will be necessary to fit the pin in the cavity, mark it about the proper length and remove it to cut it off. Then file it down to some extent and perhaps flatten that portion extending into the cavity with a hammer on the anvil so as to conform with the flat shape of the tooth labio-lingually. Before setting in cement it should be tried in and note taken of its length, its size and proper position to allow gold to be packed around it, and its capability of retaining the filling. (Figs. 177 and 178.) 4. Preparation 0} cavities in bicuspids and molars which do not involve the occlusal surface. While the general rule is laid down that all proximal cavities in bicuspids and molars should be extended through to the occlusal sur- face there are cases in which it is better practice not to do so. In the very old, the very young and in cases of immunity to caries it is not always wise to extend proximal cavities to the occlusal surface, but such operations must be looked upon as temporary in character. There is more or less recession of the gums around the necks of the teeth as age advances. The gum tissue which once filled the inter- proximal space does not more than half fill it at fifty or sixty years of age. These open spaces between the teeth serve as pockets for the collection of food which ferments and acts as a starting point of decay. The cementum is exposed and decays rapidly. In such cavities which are usually 'shallow and girdle the tooth it would be manifestly unwise to extend through to the occlusal surface. There is plenty of access, the contact is far occlusal to the cavity and the tooth is thick enough occluso-gingivally to bear any stress which might come upon it. Be- sides old patients should be treated with a good deal of consideration. Radical and painful operations should be reserved for those in the vigor of life. Old people dread dental operations even more than the child who has been told of the horrors of the dental chair. For many reasons, as has already been said, it may not be wise to make a full extension of cavities occurring in the proximal surfaces of the teeth of the very young. These patients are often so nervous and restless in the dental chair that anything like ideal operating CAVITIES IN BICUSPIDS AND MOLARS. 211 cannot be undertaken. It is better in such cases to do temporary work rather than create a dread of dental operations in the minds of young patients. Again the warning must be sounded that oversen- sitiveness, etc., must not be made an excuse for improper extensions. While we must all admit that such cases are met in practice yet there are not nearly so many of them as some of the old operators would have us believe. Often a large proximal cavity is found in the mesial surface of a first permanent molar and after it has been opened up and prepared for filling the beginning of a cavity is found in the distal surface of the second bicuspid. Now comes the problem. What should be done with such a defect ? If it is left without a filling it is certain to decay. If a small filling is inserted whose margins are in contact with the adjoining filling recurrence is almost certain within a very few years. Should the whole proximal surface together with the neces- sary step be cut out now, or should an attempt be made to get a clear- ing margin to a filling confined to the proximal surface ? The answer to these questions depends upon the conditions present. If the patient be a young girl and caries progressive and a full extension w^ould seem impossible a small cavity may be prepared. It must be explained to the patient that this is a temporary operation which will need careful examination every few months. Any change of color about the filling will be a signal for its removal. By this method perhaps two or three years have been gained and the patient at this time will be glad to have a more permanent operation made. If the patient be robust and the dentin not too sensitive and a tendency to caries and lack of care of teeth, the cavity should be prepared in the most ideal manner. Then there is the middle course which may be followed if there is a marked immunity to caries. The cavity may be extended as much as possible to clear the margins but yet confining it to the proximal surface. There are many cases of thick necked teeth where this preparation will have fairly good cleansing margins. The management of this type of case in practice will indicate what may be done with similar cavities in other locations. Many times small cavities are found in the proximal surfaces of teeth in patients of middle life which have not increased in size for years, or perhaps at one time decay was rapid but for some cause or another has ceased. The walls of these cavities will be dark or even black in color, the enamel about them does not seem to have its normal his- tological structure when cut, the dentin in the bottom of the cavity does not seem to be sensitive. In some of these cases there may be a 212 PREPARATION OF CAVITIES FOR FILLINGS. slowly progressing caries at only one location in the cavity. Radical extensions of cavity margins are not indicated in such cases. It is not necessary to cut such cavities through to the occlusal surface if there is abundance of access and there is sufficient thickness of tissue left to bear the forces of occlusion. Technique. — The technique of preparing proximal cavities in bicuspids and molars which do not involve the occlusal surface is quite simple. They are simple cavities and are prepared as buc- cal, labial, or lingual cavities. There is no force to dislodge the filling. 5. Preparation 0} cavities in the proximal surfaces of bicuspids and molars which involve the occlusal surface. The preparation of cavities in the proximal surfaces of molars and bicuspids opens up the "question of extension for prevention" again. While there may be excuses for not extending proximal cavities in the anterior teeth there cannot be the same excuses for not doing so in the bicuspids and molars. These teeth are wider bucco-lingually than the anterior teeth, the proximal surfaces are often flat which in a measure accounts for more frequent failures in these teeth than in the anterior teeth. The bicuspids and molars are usually closer together and rarely as well cared for as the incisors. The outline form depends upon the age, and sex of the patient, the character of the carious process, the strength of the closure of the jaws and the friability of the enamel. The extent of the caries is a fac- tor in deciding the location of the outline only when it has gone beyond the susceptible areas. All small cavities of decay are extended until immune areas are reached. The gingival wall is cut away until the margin of the filling will be covered by healthy gum tissue. The buc- cal and lingual walls are extended until the margins are quite clear of the adjoining teeth and may be kept clean by the action of the lips, the tongue, the tooth brush and food in passing over them. The outline of such cavities on the occlusal surface depends to some extent upon the depth and direction of the fissures. While cutting proximal cavities through to the occlusal gives more perfect access to the proxi- mal cavity it also gives an opportunity for cutting out defective grooves or fissures in the occlusal surface and forming a step for the filling which is the chief source of retention. The outline in the occlusal should be formed so as to give the greatest amount of retention for the filling with the least cutting away of tissue. The buccal and lingual walls should be parallel and at right angles to the seat of the cavity. There should be no acute angles or irregularities in the outline CAVITIES IN BICUSPIDS AND MOLARS. 213 Technique. — In the ordinary proximal cavities where the occluso- proximal marginal ridge has not been broken away and but slight defects in the occlusal fossa the simplest method of procedure is to cut into the fissure in the occlusal with an enamel drill or fissure bur about ^ mm. in diameter. This instrument should be carried right through the marginal ridge leaving a slot, the edges of which can be broken down with a chisel. If the cavity be a distal one, Black's side instruments work admirably. At this juncture the decay in the proxi- mal cavity may be removed with spoon excavators and the cavity washed out with a stream of tepid water. If the rubber is now applied and the cavity dried the full degree of extension may be decided upon. In the great majority of cases where the proximal decay has been at all extensive the buccal and lingual walls may be cut back with the chisel. If the enamel is supported by dentin it will be impossible to cut it back with the chisel until the dentin is first removed. This may be done with an inverted cone bur which is placed in the seat of the cavity and carried from the center to the buccal and then carried towards the occlusal undermining the enamel. This may be repeated on the lingual wall and if the gingival needs extension it may be cut with the same instrument. The chisel will now shave back the enamel slightly beyond the point of the removal of the dentin. A narrow necked chisel may be passed between the teeth to shave the gingival enamel away. In many of these cases it is difficult to control an inverted cone bur along the seat and keep it from jumping out of the cavity or dropping dangerously near the pulp. If an Ivory matrix is adjusted the bur may be held tightly against it while it is cutting and thus pre- vented from doing what was not intended. The outline of the step should be completed by carrying an inverted cone bur i mm. in di- ameter as far to the opposite side of the tooth as the fissures extend and at this point carried to the buccal and lingual enough to make the ca\ ity at the extremity a little more than ^ mm. wider bucco-lingually than any other point in the step. Instead of widening the extremity of the step as just described it may be deepened about half a millimeter and slightly undercutting buccally and lingually. This method is applic- able where there are no fissures or angular grooves requiring removal. There is always some difficulty in properly trimming the enamel at the junction of the occlusal outline with the proximal. A careful study of the behavior of the enamel as it is cut away is the only guide to the proper beveling. The resistance form of cavities in bicuspids and molars is of first importance because these teeth and their fillings are called. 214 PREPARATION OF CAVITIES FOR FILLINGS. upon to bear heavy pressure and sudden impacts from hard substances in the closure of the jaws. The chief dependence to resist this heavy stress must be in a flat seat and step which are at right angles to the force applied. There should be no dependence put in grooves or under- cuts in the walls of the cavity to resist the stress of occlusion. As the outline form is being gained the resistance form is being provided for. The inverted cone bur which was swept across the gingival wall made the seat flat from buccal to lingual and from the cavo-surface angle to the axial wall. And as the step was being cut out with the same form of instrument it was made flat. The junction of the axial wall with the step should be slightly rounded just so as not to leave a sharp corner which might be the starting point of stretching the gold under the heavy biting in some mouths. If decay has removed a good deal of the axial wall thus lessening the area of the step it may be restored with cement and formed as if it were dentin. The retentive form is largely provided for in the resistance form and the outline form. However, there are forces which may dislodge fillings in bicuspids and molars though they would resist the heaviest of stress. Such fillings must be so placed as to prevent their being tipped from the cavity or lifted directly out. The tipping stress is overcome by the dovetail in the occlusal surface and by providing sufficient bulk of gold in the step so that portion of the filling in the proximal surface may not be broken away from the step. As the buccal and lingual walls are being cut back the inverted cone bur is allowed to cut deeply into the bucco-gingivo-axial angle and carried occlusally about two-thirds the distance to the step, thus making the slightest grooves, which widens the cavity bucco-lingually at the seat and not at the step. It must not be understood that the outline is wider bucco-lingually at the seat than at the step. It is only in the depth of the cavity that it is wider. A slight undercut in the step will provide against the lifting of the filling if the walls cannot be wid- ened as just mentioned or if the proximal cavity is to be filled with non- cohesive gold or tin-and-gold, and finished with cohesive gold. The convenience form has already been provided for in the angles cut at the seat and in opening up the cavity to the occlusal to gain free access. There is no more fatal mistake in the formation of this cavity than allowing the proximal walls to diverge as they ap- proach the gingival. Even if such cavities are successfully filled the least condensation of the filling after it is inserted will result in the gold drawing away from the margins. CAVITIES IN BICUSPIDS AND MOLARS. 215 The enamel walls should be first cut in the length of the rods and then the cavo-surf ace angle beveled the required amount at every point. If the operator notices the manner of cleavage of the enamel while trimming the walls he will be guided in their final polishing and beveling. Any mistake in the proper bevel of the enamel is sure to be followed by fractures of the enamel around the filling. Technique. — A disk will trim, bevel and polish part of the buccal and lingual walls on the proximal and part on the occlusal. A disk will not reach the margins near the gingival without cutting too much bevel nor will it reach the walls at the extremity of the step. These locations must be trimmed with a bur. A chisel will trim the gingival wall. Darby-Perry gingival enamel chisels will sometimes do good service at these points. (Figs. 179, 180, 181, 182, 183 and 184.) If any decalcified tissue remains over the axial or pulpal wall it may now be carefully cut away and the cavity cleared of any chips. The procedure of preparing these cavities is slightly modified if the proximal decay is extensive enough to undermine the enamel Fig. 180. Fig 181, Fig. 182 Fig 183. Fig. 184 Fig 179, both buccally and lingually. In such cases the walls are readily cut away with the chisel and the seat is easily formed. What is of con- siderable moment in these cases is the support of the buccal and lin- gual cusps and at the same time to get enough resistance form for the filling. Caries has reduced the area of the step and the area of the seat cannot be increased by cutting into the tooth until the axial wall is at right angles with the seat and step, without involving the pulp. The next best thing to having a step of dentin is to have one of cement. The cement serves the purpose of a non-conducting lining and a support for the metal filling. Lower bicuspid cavities deserve special mention inasmuch as they are of different form from the uppers. Proximal decay in lower first bicuspids which have low lingual cusps must be prepared as the ante- rior teeth. The groove between the cusps is rarely defective in the low cusped variety. In the high cusped variety there are usually two pits on the occlusal separated by a ridge of perfect enamel which need not be cut through to form the step if the occlusion is not heavy. These 2l6 PREPARATION OF CAVITIES FOR FILLINGS. teeth are often wide enough bucco-lingually to permit of the whole cavity being dovetailed. The lower second bicuspids demand more resistance form, and even though there is a good transverse ridge it should be cut across to get enough resistance and retentive form to re- tain a large proximal filling. In special large mesio-occlusal cavities in upper molars there is often some difficulty in managing the mesio-buccal cusp which has become undermined. The cusp is usually high and not well supported by dentin. If a fissure should run over the buccal from the central fossa then there is no doubt about what should be done. Cut the whole cusp down with a stone as far distally as the central groove^ It should be cut low enough to leave room to be covered with suffi- cient bulk of filling material to bear the stress of mastication. And if it be cut further rootwards as it approaches the central groove giving it a general slant to that portion of the cavity it will help to resist the tipping stress on the filling. The same method of managing the disto-lingual cusp will often add to the retention of the filling and re- move a weak cusp which is likely to be fractured. Mesial cavities in lower molars occasionally involve one of the cusps and need the same treatment. (Fig. 185.) There is a class of cavities in molars which is often puzzling to the beginner. They occur as the result of defective enamel over the whole occlusal surface. Caries often ceases after the whole enamel surface is stripped off. There are spots of penetration but for which they might not need opera- tive interference. The pulps are alive and apparently normal and the patient under fifteen years of age. It is mostly considered wise not to devitalize such pulps if they can be retained alive. Grind off any project- ing spiculas of enamel. Remove the decayed tissue with spoons and if hard remove with large round burs. The only force which is liable to dislodge a filling from such a tooth will be a lifting one. To overcome this and to keep the filling from being forced off the end of the tooth cut a continuous groove with an inverted cone bur all the way around the tooth about 'midway between the enamel and the probable location of the pulp. A groove made with such a bur will have undercut enough to resist the lifting stress. If a groove cannot be cut all the way round, good sized pits may be cut at the four corners. These will give sufficient hold for a filling if it is not built too high. (Fig. 186.) Fig. 185. Fig. 186, THE TECHNIQUE OF INSERTING A SCREW POST. 217 THE MANAGEMENT OF LARGE PROXIMO-OCCLUSAL CAVITIES IN PULPLESS BICUSPIDS. Bicuspids are so narrow mesio-distally and the pulp cavity is so situated in the crown that when the necessary cutting is done to re- move the pulp from a proximo-occlusal cavity there is little dentin left to support the cusps. It usually happens that if a bicuspid has decayed deeply enough in one surface to involve the pulp the opposite surface is also defective. This increases the weakness of the cusps. With the present knowledge of inlays it is hardly ever advisable to fill such bicuspids with gold foil. The malleting of so large a filling is sufficient to endanger the walls by wedging the gold between them. Very occasionally a post might be inserted in the root canal of a bi- cuspid to act as a support to a gold filling. Such a post is more serv- iceable in lower bicuspids where the transverse ridge is not often de- fective and the post serves for retention without cutting a step across the occlusal. THE MANAGEMENT OF LARGE CAVITIES IN PULPLESS MOLARS. The secret of success in filling large cavities in molars is to cut away the enamel freely. Leave as little enamel exposed to occlusion as possible. Grind it low enough to be well covered with filling ma- terial. Enamel exposed to occlusion in a pulpless molar must be sup- ported by a large bulk of dentin or failure is certain. Posts screwed into the root canals often assist in supporting a large proximo-occlusal filling which would otherwise have to be supported by cutting deeply into the dentin of the tooth, thus unnecessarily weakening the whole structure. Large cavities in the lower molars rarely need a post for the retention of the filling. The pulp chamber may be used for this purpose by cutting a groove around its walls at the base. The bulk of filling in the chamber will be strong enough to resist any tipping stress and the undercut will resist the lifting force. THE TECHNIQUE OF INSERTING A SCREW POST. The technique of inserting a screw post into a root canal for the purpose of supporting a filling or a tube for a jacket crown is simple and yet has to be done a few times to gain speed and get the best re- sults. The screw posts which are the most suitable have square heads with a tapering thread as a screw nail. The thread is sharp and will cut into the dentin as it is forced into the canal. Select the proper size of post, ream the canal slightly smaller than the post. Screw the 2l8 PREPARATION OF CAVITIES FOR FILLINGS. post in and out a couple of times. Mark the point on the post when screwed into place at which it should be cut off to be properly covered with filling material. Remove the post, nick it deep enough with a file so as it will twist off when fully twisted down to place after being dipped into soft cement or chlora percha. A post to be of service should not extend through the filling nor yet be so short that the fill- inty cannot be thoroughly packed around it. If the post is intended to resist a lifting force that portion of it which is in the filling should be riveted to form a head on it. There is always some danger of splitting a root by screwing a post in too tightly. CHAPTER XI. THE TREATMENT OF SENSITIVE DENTIN. BY J. P. BUCKLEY, PH. G., D. D. S. GENERAL CONSIDERATIONS. It is claimed by the best authorities that "in the normal condition dentin should he without sensation; and that the source of sensitive dentin, or of impressionable pulps, lies in their continued subjection to irritation by which responsiveness is developed" (Barrett). This view is, I believe, generally conceded to be correct by all who have given this subject their attention. It is true that in the preparation of cavities for fillings we find few teeth the dentin of which is without sensation. This fact is not surprising, nor can it be construed as being contrary to the statement that normal dentin is not sensitive, when we remember that there are few teeth in the mouths of patients demanding the services of the dentist, the dentinal fibrillae and pulps of which have not been subjected to continued irritation. In the discussion of means and methods by which the sensitiveness of the dentin can be allayed I shall not attempt to enter into the details of many histologic and pathologic phenomena which are certain to arise in the consideration of the therapeutics of this subject; but shall confine myself largely to the drug aspect. It is desirable at the outset that the reader should understand and appreciate the fact that there is no other one source of failure in operative dentistry so great as the improper preparation of the cavity. This result does not always follow because of ignorance on the part of the operator of the principles involved in cavity preparation, but oftentimes because the patient will not permit, or the operator does not feel justified in inflicting, the pain necessary in carrying out those principles. The sensitiveness of the dentin can be obtunded in no small degree by the use of various therapeutic agents; and I might state that there are few operations which we are called upon to perform wherein the patient will appreciate our efforts more than in this by applying drugs and remedies for the mitigation of pain. But in order to apply intelligently and successfully any remedy, whether it be a drug or an agent, to the dentin and thereby obtund the sensitivity of the dentinal 219 220 THE TREATMENT OF SENSITIVE DENTIN. fibrillas without endangering the vitality of the pulp itself, we must be familiar with several factors or conditions, which I cannot with propriety here discuss, in detail at least. For instance, a thorough knowledge of the anatomic and histologic structure of the tooth is of the highest importance, as is also a knowledge of the pathology, not only of the fibrillae, but of the pulp tissue as well — the changes which these structures are capable of undergoing if unduly irritated by the application of the remedy employed. Still another factor of equal importance, and one which more directly relates to the phase of the subject under consideration, is a knowledge of the pharmacologic action and the therapeutic application of the drugs and remedies used for this purpose. The tendency in dentistry as well as in medicine today is towards rational therapeutics. Empirical methods of treatment are being rapidly relegated to the past. Before using a drug or an agent for allaying the sensitiveness of dentin, or for any other purpose, we should know what action to anticipate from its employment. This is not too much to expect from the trained dental practitioner of today. THERAPEUTICS. The remedies suggested for obtunding sensitive dentin have been many and varied. I shall discuss only those which, from clinical experience, have proved of sufficient value to merit consideration; and .for convenience of study, will divide them into four general classes. I. Physical Agents. — Any agent, whether heat, cold, light, electricity, or any influence whatever, if employed in the treatment of a diseased condition, is a remedy. There are some physical agents by the proper use of which the sensitiveness of dentin can, in a measure, be obtunded. (i) Heat. — The application of dry heat to a sensitive cavity, especially in conjunction with a dehydrating agent such as absolute alcohol, is always an aid; and this is accomplished by means of heating dry air, and gently directing a current of air thus heated into the cavity which has been isolated by the rubber dam and moistened with the dehydraung agent used. Care must be taken not to primarily cause pain, otherwise the object of using the agent would be defeated. Several apparatuses have been devised for heating the air. Dr. Rudolph Beck, of Chicago, has recently perfected a convenient electrical device by means of which compressed air can be heated as it passes through. Other such devices are on the market. The modern switch- THERAPEUTICS. 221 board has a heated air syringe as a part of the equipment. In the absence of any of these the chip-blower can be employed; however, with less satisfaction. Inasmuch as heat is used in conjunction with another and more important class of remedies, I shall refer to this agent later. (2) Cold. — A lesser degree of heat, commonly designated coldy is another physical agent sometimes employed for the purpose of desensitizing the dentin. Heat may be abstracted from the tooth structure by spraying the cavity with a highly volatile liquid, like ether, rhigolene, or ethyl chlorid. In the use of these agents, advan- tage is taken of the physical law that a solid in changing its form to a liquid, or a liquid in changing its form to a vapor or gas, must abstract from the thing to which it is applied, a certain amount of heat in order to effect the change. Ether, or combinations containing ether, and ethyl chlorid, both used as sprays, have proved valuable in some instances, especially shallow cavities near the gum the dentin of which is difficult to obtund by the usual methods employed, and to which reference will be made later on in this chapter. A precaution to be taken to prevent primary pain in applying this remedy, is to fill the cavity temporarily with stopping, and direct the spray first on this and surrounding parts, after which the stopping can be removed and the spray directed into cavity without any appreciable pain. The degree of refrigeration must not be carried to the point of having a possible deleterious eflfect subsequently upon the pulp or gum tissue. (3) Light. — A form of energy called light has recently been brought forth as having a peculiarly favorable effect upon hypersensitive patients. In one method the rays of light are colored by passing through a blue glass. This is accomplished by darkening the room and employing a blue bulb (i6 or 32 c.p.) on an ordinary electric socket. Whether the light acts locally, or affects the vision and thus the general nervous system, has yet to be demonstrated. The result of the author's experience with this agent has not been encouraging. It is true that light differs in effect from heat, though both come from the same heated body. This phenomenon is observed in the action ^ of light on certain chemicals; for example, the silver salts, some of which are used as obtundents, undergo a chemical change when ex- posed to sunlight or luminously hot bodies. (4) Electric Current. — This agent has been employed as a means of carrying certain drugs into the dentin and pulp tissue for obtundent purposes. The method is called cataphoresis; but because of the ^ 222 THE TREATMENT OF SENSITIVE DENTIN. expensive and complicated apparatus, the length of time required to obtund as well as oftentimes unsatisfactory, and, in not a few instances, disastrous results, the method has generally been discarded. II. Eschar otics or Caustics. — Escharotics, or caustics, are agents that destroy or disorganize the tissue upon which they act. Any drug or agent, then, which will cauterize the dentinal fiibrillae, will obtund sensitive dentin. There are many drugs, however, belonging to this class that cannot be used for this purpose because of their deleterious effect upon both the tooth structure and the pulp tissue. For instance, the strong mineral acids will disorganize the protoplasmic dentinal fibrillae; but they will also disintegrate the inorganic structure of the tooth. Arsenic trioxid has a specific poisonous action upon the fibrillae, but there is no known means of preventing the same deleterious effect upon the cells of the pulp tissue. The most valuable escharotics for desensitizing the dentin are: Phenol, Trichloracetic acid. Zinc chlorid. Silver nitrate. It must be noted that, while these agents will obtund, the ultimate result is too often produced, with the possible exception of phenol, at the expense of quite as much suffering as they save. Phenol has local analgesic properties besides that of cauterant, and will, therefore, be discussed under another and more important class of agents. Zinc chlorid in various strength solutions can be used to advantage in a class of cavities where the decay or softened dentin does not extend too close to the pulp. Zinc chlorid coagulates albumin and in the process hydrochloric acid is liberated. For this reason the application of strong solutions is painful and should not be employed in deep cavities unless the irritating action of the agent is modified. This can be done to a marked degree by selecting alcohol and chloro- form as the vehicle in which to make the solution. A useful formula is here given : I^ — Zinci chloridi, gr. xx Alcoholis, f. 5 iv Chloroformi, q. s. ad. f. § j — M. Sig. — Apply to the cavity on a small pledget of cotton and gently evaporate to dryness. Note: If the zinc salt does not make a clear solution in the alcohol it indicates that some of the salt has been oxidized; the solution can be cleared by adding one drop of hydrochloric acid. THERAPEUTICS . 2 2 3 This remedy is a disinfectant and it has the added advantage of sterilizing the dentin at the same time that it produces its obtundent effect. Trichloracetic acid in concentrated solution causes considerable pain when first applied to a sensitive cavity, therefore defeating the object of its use; but in a lo or 15 per cent solution it produces but little pain or inflammatory reaction. In this strength it can be em- ployed; but not always with satisfactory results. Silver nitrate is perhaps the only known prophylactic for decay. In the posterior part of the mouth where the cementum is exposed to external influences and thus sensitive, or in shallow cavities, especi- ally in children's teeth, the use of this drug, in the solid pencil form or in various strength solutions, will be found valuable, both as a means of reducing the sensitiveness and preventing further ingress of caries. As an agent for obtunding the sensitivity of the dentin in an ordinary cavity, it should not be considered for various reasons. When the agent is employed for the purposes above mentioned, the cavity, after the application, should be kept free from saliva for a few minutes, and, if possible, exposed to sunlight, thus decomposing the silver salt as referred to in this chapter under the subject of light. In the absence of sunlight, a practical means of decomposing the salt is by the use of the electric mouth lamp. A solution of sodium chlorid should always be at hand when using silver nitrate, and in case any of the latter agent should accidentally get on the mucous membrane of the patient's mouth its action can be checked at once by rinsing the mouth with this antidotal solution. III. Local Anodynes or Local Anesthetics. — A local anodyne is an agent which, when applied to a part, relieves pain. A local anes- thetic is an agent which, when applied, produces insensibility to pain in that particular locality. According to Long, it rather produces a condition of analgesia, which means the absence of sensibility to pain, as distinguished from true anesthesia, the absence of all sensibility. In the judicious use of agents belonging to this class the author firmly believes will ultimately be found the surest and safest road to success. The following agents, or a combination of two or more, will be found to be of the utmost importance: Cocain, Phenol, Menthol, Ethyl chlorid, Oil of cloves, Ether, Eugenol, Chloroform. Cocain is one of several alkaloids, this being by far the most im- portant, obtained from the leaves of Erythroxylon Coca, a plant 224 THE TREATMENT OF SENSITIVE DENTIN. indigenous to Peru and other South American states. Both the alkaloid, cocain, and the alkaloidal salt, cocain hydrochlorid, are used in various ways for obtunding sensitive dentin. The alkaloidal salt was formerly recognized by the United States Pharmacopeia as cocain hydrochlorate ; but in the last edition (1900) it is called cocain hydrochlorid. An important physiologic property of cocain to be remembered here, is its power, when applied directly to the mucous membrane or when injected or forced into the pulp tissue, of inducing a condition of analgesia in the part by paralyzing the sensory nerve filaments. In addition to this it causes a blanching of the part which is subsequently followed by congestion. It should also be remembered that pharmacologists have proved, beyond a doubt, that cocain is a general protoplasmic poison; that muscles as well as nerves and nerve- ends cease to contract or to conduct stimuli when they are exposed to even dilute solutions of the drug. The only reason that the delete- rious effect is more noticeable upon nerve than upon other kinds of tissue is that here we are dealing with the medium of sensation and expression. The author deems it wise to call attention to these well-established physiologic, pharmacologic and pathologic facts, for many instruments have recently been devised for forcing various strength solutions of cocain hydrochlorid, not only into the dentinal tubuli, thereby para- lyzing the fibrillae, but into the pulp proper, anesthetizing this organ as well. In view of these facts it would appear that we are seldom, if ever, justified in completely anesthetizing the pulp of a tooth for the purpose of painlessly preparing a cavity therein. Therefore under the subject of cataphoresis in this chapter, little was written; and for the same rea- sons, the method of anesthetizing the pulp by high pressure anesthesia, for obtundent purposes only, will not be considered. Both of these methods will be discussed in a subsequent chapter on pulp removal. Cocain and the alkaloidal salt, cocain hydrochlorid, are safe and valuable agents for obtunding sensitive dentin, if confined to the dentinal structure of the tooth. Frequently in deep-seated cavities, especially in children's teeth, the sensitiveness can be completely overcome by sealing in the cavity for a day or two a qreamy paste made by mixing the alkaloid cocain with liquid petroleum. The revised edition of the United States Pharmacopeia now recognizes an oleate of cocain (5 per cent), which can be used for this purpose. The paste or oleate should cover the entire surface of dentin which we sub- sequently expect to excavate. Good results can also be immediately obtained by the us ■ of the following remedy: THERAPEUTICS. 225 I^ — Cocainae, gr. xx Chloroformi, f. 3 ij Etheris, q. s. ad, f. 5 j -M. Sig. — After the rubber dam has been adjusted, apply to the cavity on a small pledget of cotton and evaporate to dryness. In the use of this remedy, advantage is taken of the physical law previously referred to in this chapter under cold. As the volatile liquids, ether and chloroform, evaporate, a certain amount of heat is abstracted from the tooth structure, and a coating of the alkaloid, driven to an extent into the dentin, is left in the cavity. This remedy will not completely obtund all sensitive dentin, but its use will be a material 'aid. There can be no objection in favorable cases, provided the dentin has been previously sterilized, to using aqueous solutions of cocain hydrochlorid with uniform pressure over the entire area of the cavity, thus forcing the anesthetizing solution an equal distance into the dentin. This is an extremely difficult thing to do without forcing the solution at some more favorable point in the cavity through the tubuli and into the pulp. However, there are cavities where good results can be accomplished by the careful use of this method. In some cases of gingival cavities good results can be obtained by hypoder- mically injecting a i or 1.5 per cent solution of cocain hydrochlorid into the pericemental membrane somewhere near the apex of the root. This practice should not be generally recommended. Menthol, a stearopten obtained from the essential oil of pepper- mint, can be substituted for the cocain in the above prescription with ether and chloroform, and used in exactly the same manner. An oily liquid (mentho-chloral) can be formed by heating together over a water-bath or rubbing in a mortar, an equal amount of menthol and chloral. This remedy will be found efl&cacious by sealing in the cavity for a few days. f Oil of Cloves. — A profound analgesic effect can be produced upon sensitive dentin, especially in deep-seated cavities, by using oil of cloves and heat in the following manner: After carefully desiccating the dentin by means of warm alcohol and gentle heat, a pledget of cotton saturated with oil of cloves should be placed in the cavity and a current of heated dry air directed thereon until the cotton is nearly dry. This should be repeated as often as the case demands. Eugenol, an oily product, is the chief constituent of oil of cloves and can be used in the same manner as above described. Phenol. — It is gratifying to the author to know that in the last IS 226 THE TREATMENT OF SENSITIVE DENTIN. revision of United States Pharmacopeia (1900), the publication of which appeared Sept. i, 1905, the product heretofore erroneously 'called carbolic acid has been recognized by its correct name, phenol. This agent can be substituted, with equally good results, for the oil of cloves or eugenol as described in the foregoing method. Care should be taken here, however, in directing the heated air so as not to cause the fumes of phenol to escape on the patient's face. Oil of cloves, eugenol and phenol are three true local anodynes, and any one of which, if hermetically sealed in a cavity for a few weeks, will check the continued irritation of the fibrillae and pulp, thus aiding nature to restore these structures to their normal condition when they should not be responsive. By this means, then, the sensitiveness of the dentin can also be allayed. Ethyl chlorid, ether and chloroform, by their rapid volatility, produce a condition of analgesia, thereby obtunding sensitive dentin, as previously explained in this chapter under cold. IV. General Anodynes or Analgesics. — General anodynes or anal- gesics are remedies which relieve pain without necessarily inducing ■ unconsciousness or general anesthesia. They may accomplish their object by acting upon the perceptive centers of the brain, the afferent paths in the spinal cord, or the peripheral nerve through which the painful impression is transmitted (Stevens). In order to do permanent work for certain highly nervous patients, it is sometimes necessary to resort to the administration of this class of drugs. The agents largely used for this purpose are: Opium. Nitrous oxid. The bromids, Chloroform. Opium is a most powerful analgesic, and while there are some dental conditions where this drug, or its chief alkaloid, morphin, is truly indicated, it ought not, in the author's judgment, to be given for the treatment of sensitive dentin. The bromids of potassium, sodium and ammonium are valuable drugs in certain cases. Perhaps there is no drug which will quiet a nervous patient more readily, when the nervousness comes purely from fear or dread, than potassium bromid, which is the represen- tative of this class. In such cases, where it is deemed necessary, the following prescription will prove helpful: I^ — Potassii bromidi, 5 jss Syrupi sarsaparillae comp., f.5 iij — M. Sig. — Take a tablespoonful in water after meals the day before coming to the office. THERAPEUTICS. 227 Nitrous Oxid. — There are several apparatuses on the market by which nitrous oxid gas can be administered through the nose. With the newer and improved gas outfits oxygen can be mixed with nitrous oxid in varying proportions, as the case demands. It is possible with such an apparatus to carry the patient just to the analgesic stage, and hold him there indefinitely until a sensitive cavity has been pain- lessly prepared. In cases where the operator feels that it is necessary to resort to this method, good results can be accomplished. Chloroform. — With the patient in the upright position, chloroform can be carried to the analgesic stage and sensitive cavities prepared. Most authorities agree, however, that chloroform should not be administered unless the patient is in the recumbent position, and that the analgesic stage is the most dangerous. Death has been known to occur suddenly, after a few inhalations, in cases of marked idio- syncrasy against the drug. The author would not suggest the use of chloroform for this purpose. In closing this chapter, may I say that most patients who repose confidence in the operator, are sensible and are willing to stand some pain in the preparation of cavities in their teeth. When preparing a cavity for a filling in a tooth, the pulp of which is vital, and where it is the intention to maintain this organ in a healthy condition, pain should be our indicator and our guide. With a true running engine, a steady hand, a sharp bur, and with the aid of some of the many remedies herein suggested, the operator ought not to expect nor to ask the patient to stand more than a small amount of pain in the preparation of the most sensitive cavity. CHAPTER XII. FILLING MATERIALS: THEIR CHARACTERISTICS, INDICATIONS FOR THEIR USE AND THE METHODS OF MANIPULATION. BY ALFRED OWRE, B.A., M. D., CM., D. M. D. The dentist of today is, perhaps, more occupied with the treat- ment of caries, both in theory and in practice, than with any other branch of his profession. Although we recognize, in the prevalent custom of treatment by filling, only a provisional substitute for some more nearly perfect one at which, in our present stage of development, we have not yet arrived, it behooves us, until we shall have outgrown it, to study closely its methods and materials. In the discussion of materials we are confronted by the fact that in the very nature of things there can be no one substance suited to all cases. There is, however, for every case a suitable material, or one which can be continued in use as such until, in our pursuit of the ideal, we progress to something more efifective. To acquire the art of filling teeth seems at the outset an Alpine task. A thorough understanding of the properties of various neces- sary materials will reduce difficulties immensely, just as in setting out for a long climb in the mountains the providing of guides and the study of maps will reduce distances and minimize dangers. It will be the aim of this chapter to point out as clearly as possible the teleological value and characteristic properties of gold, amalgam, tin, cement, and gutta-percha. We shall try to suggest when and where to apply these materials in filling cavities of teeth to insure the highest degree of success; and also to describe the methods of prep- aration, insertion, and finish. GOLD. From the earliest days of dental surgery, gold seems to have been considered the filling material par excellence. It occupies a unique prominence in operative dentistry. The ancient uses to which it was put for royal and religious ornament rendered its more common prop- erties familiar to the metal-workers of even prehistoric times. The greedy, but persistent, alchemists of mediaeval laboratories have con- tributed to modern science the results of their research for "thephilos- 229 230 FILLING MATERIALS. opher's stone." Gold has had, therefore, one great advantage — that of familiarity — over the later filling materials whose properties were little known and in whose actions scientists were slow to become interested. The appeal of gold, to primitive man, inhered in its peculiar combination of luster and yellow color. This color is deepened or raised in tone by the introduction of foreign substances, copper for the former purpose, and silver for the latter. In allotropic form it is susceptible of alteration to other than the original color. When reduced to a finely divided state by precipitation, violet, dark red, purple, brown, and even black may be produced. However, when burnished or fused, it again assumes its characteristic yellow color. Another peculiar property of gold is its extreme malleability. In this respect it exceeds all other metals. It can be reduced by beating to 3 -^ q^q ^ ^ of an inch in thickness. It also heads the list in ductility. A single grain may be drawn out into a wire over five hundred feet in length. Both of these properties are modified or ren- dered nil by alloying. As to the property of hardness, gold, when pure, lies between silver and aluminum. It is about one-third as hard as diamond. This property is generally increased by the presence of alloys, extremely small quantities of some elements (bismuth, lead, etc.) having a very marked effect, even to rendering the metal capable of pulverization in a mortar. As regards tenacity, pure gold will hold a weight of seven tons per square inch. This property, also, is reduced by the presence of im- purities. The specific gravity of cast gold is 19.3, which can be increased by condensation. In some of its precipitated forms it may be as high as 20.3. The difference is accounted for by the annealing in the for- mer case. In general, gold is weldable in the cold state in proportion to its purity; a very minute trace, i in 1000, of foreign metal such as silver, copper, or platinum, is said not noticeably to interfere with its cohesive- ness. This property is usually increased by heating. The presence of other metals alloyed with gold renders it more susceptible to the occlusion of obnoxious gases. The cohesive power is decidedly lessened by surface gases such as ammonia, hydrogen, hydrogen phosphide, and sulphurous acid gas, all of which are at- tracted to pure gold, but to a greater degree when the metal is finely divided than when it is cast. GOLD. 231 In the scale of conductivity, with silver first, at 1000 for both heat and electricity, copper is second, and gold third with a register of 548 for heat, and 730 for electricity. Its solubility is proved in aqua regia and in mixtures producing nascent chlorine, bromine, and, under certain conditions, iodine. The consideration of the qualities essential to a good filling ma- terial is a very important one. According to Dr. G. V. Black, the chief qualities are: Indestructibility in the fluids of the mouth. Adaptability to cavity walls. Freedom from shrinkage or expansion after having been made into fillings. Resistance to attrition and the force of mastic- ation. Of secondary importance are color, non-conductivity of ther- mal impressions, and convenience of manipulation. It should also be capable of receiving a polish. Bearing its constant properties in mind, let us see how gold fulfills these requirements. There can be no question as to its indestructibility in the fluids of the mouth; although iodine discolors it somewhat, it does not cause solution. It is highly capable of adaptation to cavity walls. There is neither shrinkage nor expansion; but the intermittent forces of mas- tication may work, together with the peculiar molecular structures, to produce some change in form. The yeflow color and high burnish, so beautiful in themselves, are, as fillings, more or less of an objection from the esthetic viewpoint. The contrast in color between the gold and the enamel may be rendered less noticeable by attention to the outline form of the cavity. An outline may be varied for the sa»ke of grace, without hindering the achievement of artistic results, bearing in mind, of course, that the application of gold is not, primarily, assumed to be inartistic. Conductivity is a decidedly unfavorable property. In regard to the manipulation of gold, we may say that, in general, it is difiicult, and demands sustained effort. It is generally acknowledged that success with this material exacts close application and prolonged study. As to finish, a perfect surface depends only upon the gold being reasonably well condensed. As to the use of gold, it is not easy to lay down set laws. When and where to apply it depend upon a close study of general conditions and upon the extent to which the operator's instinct for the eternal fitness of things has been cultivated. No aspect of dentistry demands keener judgment and finer appreciation of practical and esthetic values. Moreover, the physical condition and idiosyncrasies of the patient constitute a large factor in the problem. The age and state 232 FILLING MATERIALS. of health, both general and local, must be taken into consideration. Mental traits, as well, will be weighed by the tactful dentist, since the immature mind, and that which is under imperfect nervous control, must be met with special resources. It must be borne in mind that in man as in other animals the period of plasticity is the age of education. Organization and education, physical and mental, have sometimes reached a stage of balance early in life. When this happens, rather extensive gold fillings may be made for patients between the ages of ten and sixteen years. Between twelve and eighteen, the age of adolescence, the powers of the body develop at a lower rate than those of the mind; and it would be unwise to attempt the insertion of large gold jBllings unless the entire system of the patient be adequate to the strain. As the patient advances in years, the physical and nervous re- sistance must not cease to be a matter of careful consideration. If this resistance be below par, or if all extra energy be needed to nurse some disorder, it is best to postpone large gold operations. Locally we have many things to consider, such as conditions of the peridental membrane, the extent and acuteness of decay, the structure and strength of cavity walls, occlusion, wear and tear, the position of the tooth, accessibility, and possibly also the past hygiene and care of the mouth. It is quite needless to say that no gold filling should ever be at- tempted in any tooth when there is manifest pericemental inflammation. The slight loosening of the tooth as a result of deposits, or of wear and tear, need not prohibit the insertion of gold; but if any great degree of loosening has taken place, gold is generally contra-indicated. Whether the membrane is abnormal or not, its resistance should be a guide. If caries is rampant, it is often advisable not to consider gold until more favorable conditions, or a period of immunity, ensue. The firmness of the cavity walls may be insufficient to withstand the force necessary for the proper introduction of gold, especially if the strength of the bite is in the neighborhood of 175 pounds. Many malleted gold fillings fail in strong occlusions. They may also fail where the area of masticating surface has been lessened by extractions of molar teeth. In this latter case, it often occurs that proximo- incisal fillings have been literally pounded out, owing to the excess of work performed by the anterior teeth. In regard to position, the tooth may be inclined to such a degree as to render gold difficult to insert, and, in consequence, preferably omitted. GOLD. 233 The use of gold need not be restricted to any particular teeth, for instance, as has been often suggested, to the ten anterior teeth. It would be more scientific, and decidedly more practical to say that, other things being equal, we can use it wherever there is sufficient accessibility. So far, then, it becomes the ideal. Much has been said about this material. In fact, it would seem that nothing more remains to be said either for or against it. When we consider that the future preservation of the teeth depends upon the extent to which recurrence of caries can be prevented, and normal conditions and functions otherwise restored, we naturally seek a fill- ing material which will as much as possible further these aims. Statistics have been published showing that the average life of a gold filling is three years. Just so long as gold is used indiscriminately, and by all kinds of operators, will we have such figures. But these are not the statistics by which we wish to be influenced It debases our own standards, and works injustice to the best men in the profession of dentistry — those who are most influential, and who make up a very large proportion of the total number — to obscure their results by fusing with them the results of the incapable, and then strik- ing an average. Such statistics are misleading. It would be much more to the purpose to take account only of those men who are pre- eminently fitted to practice dentistry. Such men are honest enough to acknowledge failures wherever they occur, and if data were gathered exclusively from them, some reliable figures would exist upon which changes could be based when it is found that the percentage of failures is becoming too high. Not to go any further with this discussion, we may, for the moment, rest upon the statement that success hinges upon careful judgment in the selection of cases, as well as upon manipulation or technique of insertion and finish. In all discussions of the subject, so much is said as to the impor- tance of purity in gold, that it has been thought best to quote in full the Roberts-Austen refining process as given in Rose's The Metallurgy 0} Gold: Gold assay cornets, from the purest gold which can be obtained, are dis- solved in nitrohydrochloric acid, the excess of acid expelled, and alcohol and chloride of potassium added to precipitate traces of platinum. The chloride of gold is then dissolved in distilled water in the proportion of about half an ounce of the metal to one gallon, and the solution allowed to stand for three weeks. At the end of this time the whole of the pre- cipitated silver chloride will have subsided to the bottom, and the super- 234 FILLING MATERIALS. natant liquid is removed by a glass siphon. Crystals of oxalic acid are then added from time to time, and the liquid gendy warmed until it be- comes colorless, when precipitation is complete, a point reached in three or four days if ten-gallon vessels are used. The spongy and scaly gold so obtained is washed repeatedly with hydrochloric acid, distilled water, ammonia, and distilled water again, until no reaction for silver or chlo- rine can be obtained, after which it is melted into a clay crucible with bisulphate of potash and borax, and poured into a stone mold. Lack of care in any one of the operations will result in gold containing one or two parts of impurity in ten thousand. If further purity is desired, the gold may be redissolved and re- precipitated until satisfaction is attained. Gold comes to us from the manufacturer in two varieties, foils and crystals. A complete description of the manufacture of foil oc- curs in an article entitled "Gold Beating" in the Encyclopedia Brit- tanica. The sheets are usually four inches square, and the number by which each one is identified corresponds to the number of grains in the sheet; e.g., in No. 4 foil each sheet weighs 4 grs., and so on up to No. 100, or higher. Above No. 20, the sheets are rolled out instead of beaten. They may be had smooth or corrugated. Foils may be classified according as they lack or possess the property of cohesion. They are non-cohesive, semicohesive, or cohesive. Non-cohesive gold is made so by surface treatment, and although the process is not made public, we know that we can render pure gold non- cohesive by exposing it to ammoniacal gas.* The semicohesive golds, and some of the non-cohesive, can be made cohesive by annealing, which demonstrates that surface treatment had consisted, in this in- stance, of subjection to a volatile gas. Some non-cohesive foils are permanently so, and the gases covering the surface are probably of the sulphur or phosphor groups, which can- not be volatilized by heat, but condense upon the surface. Foil has been used for about a century, chiefly in a non-cohesive state. The discovery of its cohesive property, about fifty years ago, marks an era in the history of operative dentistry. It has made con- tour possible in its broadest sense, and the resulting advances are of tremendous importance. That the possibilities are not yet exhausted is another point which should encourage the profession towards progress. The crystals of gold are obtained by precipitation. The manufac- *Dr. G V Black. Dental Cosmos, Vol. 17. GOLD. 235 turers guard their trade secrets so well that we do not know what pre- cipitating agent is used. Oxalic acid, purified sulphurous acid gas, and other chemical reagents can be used, but at present these are largely replaced by electrolytic methods. There are on the market several variations of these forms, of which the fiber-like crystals are generally to be preferred. It is very probable that the crystals have a higher specific gravity, since they have never been subjected to fusion. They are usually sold in the cohesive state. Among qualities decidedly in their favor is a plasticity which renders them easy to manipulate. There has been, and still is, some prejudice against gold in this form, owing to a variable quality which can be accounted for, in a measure, by the fact that crystals are more easily contaminated. Although methods of preparation have been more or less faulty in the past, modern methods have given us a fairly rehable product, with the result that crystals have increased in use. The dentist should procure a gold which is experimentally known for its good qualities; but he must always be on the lookout lest un- scrupulous manufacturers permit deterioration. There is a variety of ways in which the dentist can shape foil as wanted, and to suit the various cavities: the ribbon, mat, cylinder, pellet, or rope. In some of these shapes it can be bought ready prepared. The ribbon is formed by taking as much as is required of a sheet of gold and, by repeated folding, reducing it to the desired width. The mat is made by simply folding the width of the ribbon upon itself according to size wanted; cylinders, by rolling the ribbon upon a flat broach. The pellet may represent from ^ of a sheet upwards, rolled to a loose ball between the ends of the fingers. The ropes or rolls are made by rolling a part of the sheet between the thumb and forefinger, or between two napkins. The heavier foils need only to be cut into strips of suitable size. Dr. Black recommends keeping the gold in a compartment where ammonia is present, thus rendering it non-cohesive, and protecting it from other gases. If desired, cohesiveness may, of course, be re- stored by anneahng. For this purpose, gas, alcohol, or electricity may be used as a means of heat. Gas, alcohol, or any open flames are objectionable on account of contaminations, grain alcohol being the least so. A sheet of mica or a porcelain tray may be used between the flame and the gold, thus reducing the objection to a minimum. The electric annealer is by far the best.* It distributes the heat evenly *The Custer electric annealer is generally recognized as the superior make. 236 FILLING MATERIALS. and at varying degrees. It also does away with handling the gold during the annealing process. In discussing the insertion of gold, it is assumed that the cavity is prepared according to the principles laid down in chapter on the preparation of cavities for fillings. Non-cohesive gold is not used very frequently for the entire cavity, since surrounding walls are necessary to its insertion, and in this day of specialization few men are enabled to acquire skill in its application. There seem to be scarcely enough points in its favor to compensate for the time consumed in acquiring this skill. Its use is limited to simple cavities. As no union of the gold laminae takes place, the wedge principle of insertion must be depended upon. The cylinder is the best shape to use for this work. It should be somewhat longer than the depth of the walls against which it is to be forced. Several cylinders are placed endwise in the cavity, and forced against each surrounding wall with a wedge-shaped instrument, thus leaving a space in the center within which are placed other cylinders Figs. 187 I 195- until it is impossible to make room for any more. The whole mass is then condensed by a suitable plugger point, the outer ends thus being forced as far as possible into the cavity. The cylinders should always be of sufficient length, so that, when tightly wedged and finally con- densed, the cavity will be over full. It is claimed for the non-cohesive filling that when it is used water- tight margins are more perfectly made, and fillings are inserted with greater dispatch, provided the peculiar skill demanded for its manip- ulation has been acquired. Filling cavities with cohesive gold, an art which requires years to master, demands less theorizing than demonstration, more actual experience than ponderous texts, so decidedly practical are all its details. Success is based upon many considerations, to some of which reference has already been made. The importance of modern cavity preparation cannot be too strongly emphasized, for upon it much de- pends. Separation of the teeth for the purpose of accessibility, and fixation to render the attachment tense, are also of moment. GOLD. 237 Figs. 198, 199. 200. 201. A large variety of plugger points is needed to fill special wants, but for ordinary purposes the dentist confines himself to a few forms with which he has become thoroughly familiar. The illustrations, Figs. 187 to 197, will be referred to as occasion demands. The shank of each plugger should bend a few degrees so that it will not interfere with the operator's view of the working point. The modern law of accessibility in cavity preparation has limited the modifications in the shank to only three besides the above; namely, the bayonet, the right angle, and, for special work, the complete reverse. (Figs. 198, 199, 200, 201, 202.) All should be finely serrated. It is also well to remem- ber that .5 mm. is about as large condensing area of a point as should ever be used. The force necessary to con- dense gold with larger areas is generally unbearable, and is also liable to cause bridging over or imperfections in solidity. Small points which pierce the gold should not be used. Another factor to consider is the manner of obtaining condensing force. Hand pressure is the simplest. The hand mallet, the automatic and other mechanical inventions, are all applied more or less. Dr. Black recommends the mallet in the hands of an assistant as the best means. It should be a rule always to place the gold where wanted in the cavity, and closely pack its laminae with a light hand pressure, then mallet until the required solidity is obtained. The force should be so directed as to distribute itself evenly over the tooth-attachment; that is, toward the long axis. This causes the least inconvenience to the patient. Perfect adaptation to cavity walls and margins, and adequate condensation, are the chief objects of attainment in these fillings. Both are interfered with by over-annealing. In fact, the very first pieces introduced in the cavity may be unannealed cohesive gold, which secures more easily, and with more certainty, the above-mentioned adaptation. Masses of gold, if too large, cannot be properly placed and condensed. For starting the filling, 3^0^ of a sheet No. 4 foil is quite sufiicient, or Fig. 202. 238 FILLING MATERIALS. an amount that may be readily anchored into one angle of the cavity. It is generally not advisable to use a mass of gold the bulk of which is more than one-third the size of the cavity. . ,,-^. A solid plug is obtained only by carefully welding each newly added mass to that already in the cavity. In doing this, the force exerted in manipulation must not in any way distort the filling or interfere Fig. 203. Fig. 204. Fig. 205. Fig. 206. Fig. 207. Fig. 203. — Axio-mesio-distal plane. Fig. 204. — Axio-mesio-distal plane. Fig. 205. — Axio-mesio-distal plane. Showing gold started. Showing floor covered and advance of axial walls Overfull and ready for finishing. Fig. 206. — Longitudinal section, Bucco-lingual plane, mesial fourth, through retention orm of cavity. Showing gold started. Dotted lines represent the outline form of the cavity. Fig. 207. — Same as Fig. 206. Showing the union complete, and surface brought up. with adaptation, but rather be so directed as further to insure adapta- tion and stability. The plugger should, therefore, generally proceed from the center to the periphery. It is never judicious to exert force on thin layers of gold covering flat surfaces. Moreover, in covering margins, especial care should be taken to have a good cushion of gold Fig 208. Fig, 209. Ftg. 210. Fig. 211. Fig. 208. — Longitudinal section, Mesio-distal plane, Buccal fourth. Showing gold started (as in Fig. 206). Fig. 209. — Showing the progression of the gold building after gingival wall has been covered. Fig. 210. — Same section and plane, but cut through middle of tooth. Showing locking of step, and proximal part of filling. Fig. 211. — Same as preceding. Gold building complete. over the margins, thus avoiding danger of the plugger point coming in contact with the tooth tissue. In filling a simple cavity, the process of building the gold is illus- trated in Figs. 203, 204, 205. Plugger points 187, 188, 191 and 196, are used in this class of cavities in the anterior teeth, and as we go back into the mouth the bayonet, 194, wiU also be needed. GOLD. 239 The filling of a complex cavity is best illustrated in the mesio- occlusal of a first upper molar. (Figs. 206 to 211.) The axio-bucco- and axio-linguo-gingival point angles are first filled, and then the axio- gingival line angle is covered, starting from each point angle re- spectively, so that the surface represents an angle of 45 degrees with the axial or gingival wall, and the latter is built out upon until its margin is fully covered. The filling should then proceed swiftly to the contact point, and, in doing so, one should as nearly as possible pre- serve a flat surface; but the inclination from buccal to lingual may vary according to accessibility. For this part of the work pluggers 187, 188, 192 and 193 are used for starting the fiUing, and 194, 195, 196 and 197 for further condensing. The step portion of the cavity is started in the same manner as the simple cavity, but instead of building up over the missing wall, the operator laps the gold over the proximal portion, and builds the whole out until it is overfull. The practice of making mesio-occlusal-distal fillings in one opera- bbDb Fig. 212. Fig. 213. Fig 214. Fig 215. fic. 216. Fig 212. — Mesio-distal plane. Showing the starting of gold. Fig. 213. — Same as Fig. 212. Showing progress of gold building and union of incisal part with the rest of the filling. Fig. 214. — Same section. Gold building finished. Fig. 215. — Axio-mesio-distal plane Showing process of gold building in carities nvolving angle Fig. 216. — Same section as 215. Gold building finished. tion should be discouraged. It is economy in every respect to make two proximo-occlusal fiUings instead; however, they may be so inter- locked as to represent the same outline form as the mesio-occluso- distal filling. The proximal cavities of the anterior teeth present some difficulties owing to the fact that we have less surrounding wall. (Figs. 212 to 214.) For illustrative purposes take the mesial of a central incisor. The gingival point angles are filled first, and the axio-gingival line angle is covered as described in the preceding case. The surface of gold should then be built toward the incisal, preserving an angle of about 45 degrees, and it should be borne in mind constantly that the lingual portion is to be kept in advance. The incisal retention form is filled 240 FILLING MATERIALS. as soon as the gold can be attached from it to the main portion, and the body of gold thus tied and strengthened. Great care should be taken in covering the margin both lingually and labially at the proper time, and also in sufficiently contouring the lingual. In cavities involving the angle v^ithout a step, the building of the gold is continued to proper contour. (See Figs. 215 and 216.) Pluggers used for the gingival retention form are 187, 188, and 189; for the body of the filling, 195, 196, and 197; for the incisal retention at times necessary to add, 190. When the incisjal edge is involved, and the step preparation has been made, the filling of the proximal portion is proceeded with pre- cisely as described until the step is reached. The retention form in the Fig. 217. Fig. 218. Fig. 219. Fig. 220. Fig. 221. Fig. 217. — Mesio-distal plane. Showing disto-pulpal angle filled. Fig. 218. — Same as preceding, further progress. Fig. 219. — Same as Fig. 218. Gold building completed. Fig. 220. — Upper second bicuspid. Axio-bucca-lingual plane. Showing the three non cohesive cylinders of gold in place. Fig. 221 — The same tooth as that in Fig. 220. Axio-mesio-distal plane, showing partially condensed mass of non-cohesive gold projecting over gingival cavo-surface angle, incisal part is then filled from the disto-pulpal angle, and the gold built dov^^n so that its surface v^^ill present an angle of 45 degrees with the pulpal wall, and on towards the proximal portion, covering the in- cisal edge. Lastly, the union of the two portions is completed, and carried out to contour. The force exerted here should always be so as to drive the whole filling more tightly into its retention and resistance forms. (Figs. 217 to 219.) In the filling of a mesio-inciso-distal cavity in the six anterior teeth, the proximal portions are filled as before; in filling the incisal portion, however, the center should proceed faster than the angles, and it is also best to build one angle out to contour first, remove the separator, and proceed with the remaining one exactly as before. A great deal has been said about the percentage of failures of adaptation to the gingival wall in bicuspids and molars when using cohesive gold for the entire cavity, although on this point statistical figures may vary quite as widely as do opinions of what legitimately GOLD. 241 may constitute such figures. Some of the best operators prefer to use a certain amount of non-cohesive gold in the gingival part of the cavity. The advantage is, besides better adaptation, a saving of time which is, of course, a vastly important factor in the economics of the question. The non-cohesive gold should not fill the whole of the retention Fig. 222. — Labial view of six anterior teeth. Showing contour and contact. form. The usual method of procedure is to place one cylinder in the axio-linguo-gingival point angle, another in the axio-bucco-gingival, with a third between, and partially force them together with the plug- gers 192 and 193. The cylinders used should be about twice as long as the gingival wall is wide mesio-distally to allow for after-conden- sation. (See Figs. 220 and 221.) The cohesive gold is now forced into the non-cohesive, using an assistant plugger, while locking the gold from the lingual to the buccal wall. Thus the cohesive gold Fig. 223. Fig. 224. Fig. 223. — Buccal view of bicuspids and molars. Showing contour and contact. Fig. 224. — Occlusal view of upper bicuspid and molar. Showing contour and contact. really forms the fourth surrounding wall for the non-cohesive. Thence the filling is proceeded with as in the operation already described where cohesive gold was used for the entire cavity. The final condensation of the non-cohesive gold takes place from the surface, by means of large parallelogram pluggers (see Figs. 197, 198, 199, and 200, the last three for distal surfaces). In finishing, it is assumed that the cavity has been overfilled to allow for trimming away of enough gold to leave a perfectly smooth surface, and still have proper contour. The instruments and appli- 16 242 FILLING MATERIALS. Fig. 225. — Occlusal view of lower bicuspid and molar. Show- ing contour and contact. ances for this purpose are many. Of them, the following are indispen- sable: A plentiful supply of corundum stones in various sizes and grits, sandpaper discs and strips, the Wilson saw frame (Fig. 226) and saws cut down to a thread-like thinness, Dr. G. V. Black's trim- ming knives (Figs. 227, 228, 229) and Dr. E. K. Wedelstaedt's gold files. (See illus- tration. Fig. 230.) Generally the first cutting is done with the aid of corundum stones or sandpaper discs and strips, depending upon locality, and, in proximal positions, the saw is an adjunct of great importance. Thereafter, the steel instruments, chisels and excavator for inaccessible places in occlusal fillings, trimming knives and files, and, for the final smoothing, cuttle-fish discs, pumice stone, whiting, or rouge, used with suitable appliances. The chief watchword in this part of the work should be: Lacerate the tissues as little as possible; reproduce natural form plus the needed contour and contact point (Figs. 222 to 225); obtain as ^ smooth a surface as possible so that an explorer will pass from filling to tooth tissue without catching. Always cut from the gold to the tooth tissue as far as possible. As to the use of the knives, only thin shavings should be cut, and the force should be directed so as not to disturb the filling. Occlusal fillings are first ground down with corundum stones and water, starting with reasonably coarse grits, and finishing with finer ones. A variety of shapes is necessary in order to reach well into grooves and variations in sur- faces. A good polish can be obtained by using fine, wet pumice stone powder applied with wooden wheels or points, rubber discs, or moosehide wheels. This may be followed with whiting and even rouge for a very high degree of polish. In buccal, labial, and lingual fillings, the use of discs should be substituted for part of the corundum work; but both these materials are very liable to cut too much into the filling. The pointed fissure burs can be used over the p^^ ^^^ gingival margin. The Black trimming knives and Wedel- staedt files are all of use here. The polishing is done as above indicated. In the proximo-occlusal fillings the saw is passed under the gin- gival overhang, and should be first drawn carefully toward the contact point, and with it as much as possible of the remaining overhang GOLD. 243 Figs. 22S 227 229 should be removed, or as much as the limitation of movement will allow. The trimming knives can now be used, and should be followed by the files, with some care to guard against too much cutting; the needed contour and symmetry of shape must always be remembered. Further smoothing is done with sandpaper discs and strips, followed by the usual polishing process. It is often necessary to carry the polishing powders on linen tape over the proximal portion, in order to finish thor- oughly. In proximal fillings in the six anterior teeth, the first cutting is usually done with sandpaper discs and strips, although the corundum stones are material aids on both labial and lingual surfaces, especially the latter. It may also be neces- sary to use the saw, knives and files for the purpose of removing the gingival overhang; but they are perhaps not needed so much here as in the posterior teeth. Polishing is done with cuttle-fish discs and strips, and with the powders. The incisal angle and edge, when involved in a filling, demand a greater use of corun- dum stones and sandpaper discs. Considered as a stopping, nothing as yet has quite taken the place of gold, although it cannot be said to apply perfectly to all cases. A full knowledge of its properties, behavior, and working qualities, is the first essential. With skillful instrumentation and bulldog persistence, one ought to be able to conquer the art of making nearly perfect gold fillings in a comparatively short time, say in from five to ten years. Reference has been made to the dis- covery of the cohesive property of gold as marking an epoch in the history of tooth- Another epoch may be said to have been ushered in by the scientific and artistic work of Dr. G. V. Black. The world- wide influence exerted by this great worker may be noted in papers, reports of clinics, etc., published in the various journals by members of the G. V. Black Club (Inc.) of St. Paul. This organization has done much to simplify gold fiUing, and, in general, not only through its home meetings, but in state, national, and international gatherings, has done much to further the progress of operative dentistry. i i Fig. 230.— Dr. E. K. Wedelstaedt's gold files. filling. 244 FILLING MATERIALS. AMALGAM. Owing to the plasticity conferred upon an alloy of one or more metals with mercury, amalgam is usually spoken of among the plastic filling materials. What takes place in the union is the lowering of the fusing point of the alloyed metals by introducing mercury, a plastic stage thus ensuing before crystallization is complete. This plasticity and subsequent crystallization — both interesting phenomena — led to its introduction as a filling material. The study of amalgam is somewhat complex because we have to deal with an alloy of certain metals not always constant in physical properties out of the mouth, and hable to still greater modification after introduced into the cavity as an amalgam. For various appli- cations in the arts, metals are alloyed to gain specific ends not obtain- able by any one of them alone: to increase hardness, strength, tough- ness, elasticity, and resistance to corrosion; to lower the fusing point; to modify color, etc. Alloy making and application were known to the ancients, although they did not always produce what they intended to, nor did they know very much about the separate elements. Alloy for amalgam fillings was introduced in the first quarter of the last century. Things were done on a more or less empirical basis until the impetus of scientific method altered matters. Although formulas may not have changed markedly, there has been undoubted improvement as to certainty of procedures and results. It was the general lack of applied science which made it so difficult for amalgam to take its present place of use- fulness, and we owe a debt of gratitude to all the zealous workers who have combined to give it that place. The early prejudice against it was due to its non-scientific composition and use. It is, perhaps, needless to say that amalgam has been criminally abused in the past, and that the better conditions which might naturally be expected from scientific workers have not been commensurate with their efforts. Its plasticity readily betrays operators into unwarranted speed — a fact which is only too soon recognized by the charlatan class. Some properties of amalgam should be noted. Its color is grayish white. It is generally spoken of as brittle, although under certain conditions it manifests a degree of malleability known as "flow." It is harder than silver, but not very tenacious. Gases are condensed upon its surface to a larger degree than with gold. As to conductivity, all alloys have less of this property than do the simple metals. These properties are modified, first, according to the number and quantity AMALGAM. 245 of the various metals added; and, second, according to the mode of making. As to the manner in which amalgam fulfills the requirements of a filling material: It may be said to be practically indestructible in the mouth. Chemical action of any kind is always more energetic in alloys, hence amalgam unites easily with oxygen and sulphur. In adaptation to cavity walls, it is nearly as good as gold. The change in form in amalgam, due to contraction and expansion, so noted in the past, has been reduced by modern science to the minimum. It with- stands attrition well, and, in general, the forces of mastication are not so manifest upon well-made fillings of this material as upon those of gold. Its color is one serious drawback. Its conductivity is low, far lower than that of gold. As to ease of manipulation, this property increases in proportion to the amount of mercury introduced in the alloy; but the operator must choose between this advantage and the superior one of firmness, for, if the latter be the desideratum, it must be had at the expense of the former. In susceptibility to polish, it fulfills the demand. The properties of amalgam decide its application, to a large extent; for instance: its color limits its use to the posterior teeth, or where it is little noticed; the possibility of easy manipulation often determines its use in cavities inaccessible to gold. So then, generally speaking, it can be used in the bicuspids and molars, especially in cases where more nearly perfect results can be obtained than by the use of gold. However, if exposed to view to any extent, it is contra-indicated. We may say that so far as it is peculiarly adapted to such selected cases, it becomes the ideal material. If success is to be obtained in amalgam work, the following points must be carefully considered: The individual metals used; the purity and the proportion of the metals; the manner of production; and the manipulative procedure. The study of the chemical and physical constants of the metals is imperative. As to the behavior of metals toward one another in alloys, it may be said that mixtures are not merely mechanical. They are in the nature either of a solution of one metal in another, or of a chemical combination. A chemical combina- tion may be a pure one, or it may provide an excess of one of the metals in which latter case the excess is mingled mechanically with the mechani- cally combined constituents. Proportion, temperature, etc., of course determine the final manner or manners of the combination. There is no hard and fast rule regarding the reciprocal action of metals in alloys. Some metals alloy easily in any proportions; some 246 FILLING MATERIALS. less easily and in only set proportions; and again others alloy with extreme difficulty under any conditions. As a rule, metals of similar chemical nature have greater affinity as alloys than those which differ. Mention should be made of the fact that only chemically pure metals 'ought to be employed. Otherwise, unaccountable variation will manifest itself. The proportion of metals is of considerable moment. Experiments have shown that like quantities of metals alloyed alike produce cer- tain results. Furthermore, the addition of a very minute quantity of some metals is capable of causing great modification in the properties of the resultant alloy. The manner of production is of tremendous importance, for instance: If metals be heated to a temperature beyond the fusing-point, a different atomic grouping may occasionally result. The length of time they are kept in the fluid state, the mixing process, the various methods of cooling and casting, may noticeably modify an alloy. In some cases when cooled slowly, they will separate into several alloys of differing compositions; that is, the alloys with a higher fusing-point solidify first. This is spoken of as liquation. At the same time spe- cific gravity may manifest itself so that the lightest alloys, if solidified last, may be uppermost. If liquation take place, there will be not only variation in composition, but also, to a marked degree, in the properties. Liquation should, therefore, be prevented as far as possible wherever constancy of properties ought to prevail. This can in the main be accomplished by rapid cooling. It is clear then, that much depends upon the manner of production. The foregoing remarks may be made more clear by a description of the process of making dental amalgam alloy: Take the formula 60 per cent silver, 35 per cent tin, 4 per cent cop- per, I per cent zinc. To make 10 oz. we shall need 6 oz. silver, 3^ oz. tin, 8 dwts. copper, 2 dwts. zinc. Zinc is added in the combination of brass, because free it is easily volatilized and oxidized. The brass, however, should be of known proportions, say 75 per cent copper and 25 per cent zinc (a constant alloy). The weight will then be 2 dwts. copper and 8 dwts. brass. The brass, copper, and silver are fused in a plumbago crucible first. The tin is fused in a separate ladle, and added as soon as the first three are in fluid condition. Fusing all the metals at once has been tried, and analysis and experiment show greater variation. Some stirring is necessary until the pouring out begins. A quarter inch steel mold about four inches wide cools the alloys fast enough. One out of every thousand melts, as above, were AMALGAM. 247 subjected to analysis by Prof. C. J. Bell in the chemical laboratory of the University of Minnesota. Five sections of the bar were made, and the percentage of each metal was very nearly the same in all, and according to formula. If thicker castings be made, liquation is very liable to take place. The bar can be reduced by means of a twelve-inch bastard file, and strained through a brass wire mesh. Iron filings from file and bench vise may be removed by passing the magnet through for several min- utes, and it is then aged by subjecting it to the temperature of boiling water for about twenty minutes; the mass is placed in a beaker, and introduced into a pot of boiling water. The silver is added for its hardening and settling qualities; it also causes expansion. Tin is added chiefly to counteract the expansion caused by the silver, and to retard the setting. Copper increases hardness and strength, and has some effect upon color. Zinc heightens the color, and somewhat hastens the setting. The percentages of dental amalgam alloys have been determined by experiment. For a detailed study of them the reader is referred to Fig. 231. the scientific investigations of Dr. G. V. Black {Dental Cosmos, Vol. 28, and elsewhere). Dental amalgam alloys are classified as binary, ternary, etc., accord- ing to the number of metals added. With amalgam the most vital point for consideration is the manipu- lative procedure. Not only is the percentage of mercury to be reck- oned with, but also its incorporation, the compression of the mass, trimming and finish, are all elements that figure prominently in the results. One reason that this material has not reached a higher plane generally is a lack of sufficient study and attention to minutiae and detail in the technique of insertion. This deficiency should be more widely acknowledged and repaired. It has been the writer's privilege to observe several hundred amal- gam operations made by Dr. F. H. Orton, of St. Paul, during the past twelve years. The results have been uniform, and as nearly perfect as are ever seen. His method of procedure is incorporated in the fol- lowing description of filling a cavity with amalgam: The cavity is prepared as for gold, with this difference, that the 248 FILLING MATERIALS. Fig. 232. — Black's hand pressure amalgam instruments enamel bevel should be somewhat longer. All cavities must be simple; if not so in the first place, they must be made so by adjusting a matrix to replace the missing wall. The matrix should be unyielding and fit closely to the tooth-surface. The amalgam is prepared by placing the mercury in the palm of the hand, and gradually adding the alloy until affinities are practically satisfied. The hand should be perfectly clean and dry. The incorpora- tion of the ingredients is accomplished by rubbing with a glass pestle. (See Fig. 231.) Both judgment and skill are necessary to obtain the proper mix; a certain crepitus is noticed when the mass is about ready, and some experience will enable one to know when this point is reached. It should be an object to have as little surplus mercury as possible when the mixing is finished; there- fore it is forced out in chamois skin or muslin with heavy pliers so much so that the mass should resemble a hard, flat cake which fractures sharply. In packing the amalgam the object is density and complete union of all the particles. As it is some- what plastic, the plugging points should be as large as the cavity will permit, and with serrated surfaces (see Figs. 232, 233, and 234). Hand pressure as ordinarily understood is not sufiicient; hence the aid of the mallet comes in, using bayonet shanks as illustrated. It will be found that it requires a rather heavy blow from the mallet to compress the amalgam, and that the blows must be repeated until the mercury appears under the plugger point. is then removed by the aid of gold foil, the two metals having a marked afl&nity for each other. A cylinder of gold foil is placed upon the surface, covered with spunk, pressed down and removed. More amalgam is then added, and the process is repeated until the cavity is overfull. Importance should be attached to the removal of the surplus mercury whenever it appears; if allowed to remain, it weakens the mass. If care is taken, the amalgam will be sufficiently crystallized to admit of trimming immediately. For occlu- sal surfaces large spoon excavators should be used, and for proximal, trimming knives and coarse cuttle-fish strips and discs. Fillings in li I Fig. 233. — Black's amalgam instruments with bayonet shanks for mallet use. This surplus mercury TIN. 249 Other positions present few difficulties in trimming. The same instru- ments with some additional chisels or excavators for special inequali- ties will be found all-sufficient. It is best to postpone for a day the final polishing. First corundum stones, and then powders, are used, as in the polishing of gold fillings. Since in time these fillings undergo a slight change in form, it may be necessary to refinish afterwards, as occasion demands. The time required to make a good amalgam filling is nearly that required for gold; therefore were it not for the fact that in certain cases it excels all other materials, there would be no economy in its use. Many large M /J cavities may be filled with amalgam v/hen the malleted gold filling would be entirely out of the question. Restor- ations of considerable magnitude are often made, whereby teeth are rendered useful for a number of years. Although amalgam is not proclaimed as the acme of desirability, it occupies a very high place as a tooth saver, and it is well worth effort and energy to increase our knowledge concerning it. There is yet a wide field open to the investigator in alloy making and application. With what has already been achieved, however, the student can and should thoroughly acquaint himself, and thus conserve time by eliminating the errors and profiting by the valuable discoveries of the past. TIN. Fig. 234.— Owre's right and left amal- gam instru- ments for use against matrices at junction o f same with c a V o-surface angle. For various reasons tin is still used by some dentists, and the ability to insert a tin filling is a test in some official examinations. Hence this material should be studied. In color it is white with a tinge of yellowish-blue. When pure it has a bright, metallic luster, and although in normal air it does not easily tarnish, it readily occludes gases. It is fifth in the order of mal- leability, foil Y¥o¥ of an inch thin being obtainable by beating. It is classified with the soft metals, and is also of a low grade of tenacity, being tenth in the scale at 2.1 tons per square inch. Its specific gravity is 7.3. It is weldable in the cold state if perfectly pure, and purity generally implies fresh-cut surfaces. When weldability has been in- terfered with by exposure to air, it cannot be restored by annealing. As to conductivity, tin ranks low: for heat, 154; for electricity, 114. Tin has been used as a filling material for a century or more; but 250 FILLING MATERIALS. it only partially fills the requirements of this purpose. It oxidizes readily in the mouth, is easily adapted to cavity walls, and undergoes no change in form unless subjected to wear, and, when so, the mallea- bility and softness markedly manifest themselves. Its color is objec- tionable. So far as conductivity is concerned, it is low enough to be of value. The manipulation is very like much that of gold. It receives a fairly good pohsh. Occasional reference has been made to its therapeutic value, when used as a filling, as a preventative of caries, etc. This seems highly improbable, excepting insofar as it replaces the carious area, as does any other filling material. Tin has been recommended for cavities which are not exposed to wear and tear, and is practically limited to simple smooth-surface cav- ities not exposed to view or wear. It may have some application to cases of young children, owing to its rather easy manipulation. It is prepared for the dentist in several forms, but the foil is chiefly used, between Nos. 3 and 10. But, as this soon loses the property of cohesiveness, the dentist had better prepare the shavings of tin himself, when wanted, by casting an ingot upon a polishing mandrel, attaching to lathe, and, with a sharp tool, cutting as fine shavings as desired for the case in hand. Its insertion is exactly according to the method pursued with gold, the only difference being that the plugger points may be more deeply serrated. The finishing, also, is the same as in the case of gold. Since science has aided us in establishing the status of things, it would seem as if the future of the tin filling were somewhat dubious. Personal opinion need not obtrude itself here, for speculation belongs only to the field of theory. ' CEMENT. Among the applied arts, cement, in its various forms, has been in use for centuries. Its introduction to dentistry did not occur until about fifty years ago. Largely owing to lack of science, it has had a degree of difficulty in establishing itself as a filling material, as also had amalgam. For that matter, its status quo, all told, is sti],l somewhat doubtful. Nevertheless, it serves many important and useful pur- poses — so much so that we have come to regard it as indispensable. Of the three kinds of cement to be considered, i. e., the oxychloride of zinc, the oxyphosphate of zinc, and the oxyphosphate of copper, the first is at present little used. The use of zinc oxychloride as "a stopping of hollow teeth" was first suggested because of its plasticity when freshly mixed, its subsequent hardening, and its apparent in- CEMENT. 251 dissolubility. Its shortcomings were soon discovered, and various modifications of the powder and liquid were tried for the purpose of enhancing its qualities, but to no avail. The oxyphosphate of zinc, introduced some years later than the oxychloride, gave promise of greater things. It has largely taken the place of the oxychloride, except for some special purposes to be noted. Upon it our main reliance was placed until quite recently — in 1891 — when Dr. W. V-B. Ames, of Chicago, brought out the oxyphosphate of copper. Some general properties of all cements should be noted: Plas- ticity, facility of setting, granular structure, low strength, porosity, marked solubility, and low conductivity. As to color, the oxychloride is nearest white, the zinc oxyphosphate has various hues, while the copper oxyphosphate is the blackest of black. The properties vary a great deal, according to composition and modes of mixing, especially those of density, setting, porosity, permeabihty, disintegration, etc. To a certain extent all cements possess the essential qualifications for a filling. But they are not indestructible in the fluids of the mouth, especially under the free margins of the gum. The oxychloride is the worse in this respect. Their adhesiveness to cavity walls is of great value. Some cements undergo change in form, particularly through contraction. None resist attrition well, although oxyphosphate of zinc and copper wear much better than the zinc oxychloride. As to colors, highly artistic results may be obtained with some of them, but the black of copper oxyphosphate limits the application of it to unexposed places. Cements are practically non-conductors of heat, and are often indicated for this reason. As to ease of manipulation, they are undoubtedly first of all materials. They are incapable of receiving or maintaining a very high polish; although when first finished the surface may be fairly smooth, with wear it soon becomes granular. Some of them are, in general, less irritating to tooth tissue than metal- lic fillings, and this is one of the most important considerations. Oxy- phosphate of copper has been found to be extremely bland when used near the pulp, or even in contact with gum tissue. In regard to the porous structure, this is capable of some reduction through modifi- cation of constituents. Turning to indications for the use of cement: At present the oxy- chloride is not used to any extent as a filling for the entire cavity, because of its speedy disintegration, and the irritating character of the chloride. Many authorities agree in indorsing it as a cavity lining because of its white color, its density, and therapeutic value. It should 252 FILLING MATERIALS. not be used too close to the pulp, because of the irritation likely to result, but it may be used to advantage in pulpless teeth for the larger portions of the canals and to fill the pulp chamber. We are considering then, practically, only oxyphosphates of zinc and copper. Fillings prepared from these materials are spoken of as temporary, it being implied that they will be replaced sooner or later by more nearly permanent ones. While this is correct, we must not lose sight of the fact that some teeth will never be filled with anything more permanent, i. e., cement seems peculiarly and preeminently to lend itself to the preservation of certain teeth. It is, par excellence, the material for use in all cases where for any reason no adequate cavity preparation can be made for the so-called permanent fillings. It is also indicated in some other cases: those of very old people, and those of younger people in whose teeth caries is acute. In the latter case it is introduced as a temporary filling in the true sense of the term, in extending the usefulness of frail or deciduous teeth. In discussing the preparation of cements, we are confronted with the large and insurmountable trade-secret proposition. The mere names indicate some of the chief ingredients; but of the various methods of production, the modifying agents used, etc., we have very little data. As it comes to the operator's hand, a cement is made up of a powder and a liquid. The powder of the oxychloride of zinc is com- posed chiefly of oxide of zinc, calcium oxide being often added to hasten setting, and other ingredients to obtain certain other proper- ties, as silicate of aluminum, magnesium oxide, sodium borate, silex, powdered glass, etc. The oxyphosphate of zinc is principally composed of glacial phos- phoric acid and zinc oxide, to which are added, for the purpose of in- creasing hardness and lessening solubility, several foreign ingredients, e. g., sodium phosphate gives the liquid a glassy consistence in hand- ling. A chemical analysis of cements shows the following impurities:* arsenic, antimony, lithium phosphate, cadmium sulphide, carbon, fluorhydric acid, nitric acid, sodium carbonate, powdered glass, silex and water glass, sodium borate, magnesium oxide, magnesium nitrate, sodium phosphate, silicate of alumina, phosphate of alumina. The fineness of the powder varies not only with different makes, but occa- sionally with different lots put out by the same maker. The finer it is, the quicker it sets. The oxyphosphate of copper is composed of the same liquid as *Dr. J. E. Hinkins, Dental Cosmos, Vol. xliii, p. 591. GUTTA-PERCHA. 253 the foregoing, and cupric oxide, with or without addition of other metallic oxides. The preparation of cements for filling cavities is not very difficult, but some care is necessary. The phosphoric acid has a tendency to crystallize. To lessen this, Dr. Ames recommends keeping it in a tele- scoping glass cap bottle, instead of one with the cork fitting within the neck. The prime requisite in mixing is thorough spatulation. Powder should be added to the liquid in only a small mass at a time, and before use the mixture should attain a putty-like consistency. In the case of oxyphosphate of copper, a creamy mix seems to give best results. It should be needless to say that the glass slab, spatula, and other instruments used in handhng cements must be scrupulously clean and well polished. Cements vary somewhat in their working qualities. Hence, good results can be made sure of only by more or less experience. The cavity preparation for cement fillings is simplicity itself, since the adhesiveness of the material may be very largely depended upon for securing the filling to the cavity walls. The complete removal of caries should in every case be insisted upon, however. In inserting the material, one must remember to overfill the cavity, and to use as nearly as possible even pressure from all points. For this work broad, flat burnishers are usually employed. These should first be rubbed upon an oil-pad to prevent the cement from adhering to them. The filling should then be left thoroughly to crystallize before trimming, which process is accomplished with chisels, trimming knives, and occa- sionally burs. A fairly smooth surface may be had by the aid of fine sandpaper discs or strips. The cement operation, with proper care, may be made a very suc- cessful one. That it has fallen in estimation somewhat, is due largely to the fact that the apparent ease of cavity preparation and of manip- ulation lend themselves to charlatanism. Used by skillful hands in the proper places, cement has, in spite of its lack of durability, a valid claim to a position among filling materials. GUTTA-PERCHA. The name gutta percha is applied to the inspissated juice of various plants belonging to the natural order Sapotacea. The term is of Malayan origin, guiia signifying gum, and percha, the species of tree from which the gum is derived. It is native in the Malay Peninsula, and although its use has long been known in the Orient, even back into antiquity, it was not introduced into the western world until early 2 54 FILLING MATERIALS. in the last century, when its great possibilities in the realm of manufac- ture were recognized. It was taken up by dentists about 1850, and, according to Dr. J. Foster Flagg, it was then suggested as a temporary stopping for frail teeth, and was recommended for its ease of manip- ulation, its non-irritating and non-conducting character, its insolubil- ity in the fluids of the mouth, and its reasonable resistance to attrition. He further asserts that with it he could make better fillings in certain places than with gold. Various modifications of it were introduced better to meet the dentist's requirements. But the difhculties attend- ing its manipulation, its non-resistance to attrition, and the gradual gain of cement, have lessened its use. Lastly, the introduction of copper oxyphosphate has almost crowded it out as a filling for the entire cavity. The properties of gutta-percha are its decidedly low conductivity, its blandness, or non-irritating character, its agreeable color, and its insolubility. It lacks hardness, even when foreign substances are introduced to increase this property. Its contraction on cooling is also an objection, as is also its more or less porous structure. It is insoluble in the fluids of the mouth; it can be reasonably well adapted to cavity walls; it changes in form, notably by contraction; it does not resist attrition; its color is not objectionable and is easily modified; it is the best material we have for non-conductivity; it is not so easy of manipulation as cement; it takes no polish at all. Gutta-percha is indicated wherever a perfect non-conductor is needed; but as it cannot be used in any place where it will be sub- jected to attrition, it is decidedly limited in its application. It is especially applicable to the filling of small pulp canals in pulpless teeth. Commercial gutta-percha is prepared by boiling and purifying in a number of ways. When nearly pure, it is of a grayish-white color which can be modified as desired. For dental uses the pink base plate gutta-percha seems to be best. It is colored by means of sulphide of mercury. Its successful use involves considerable skill. It must be heated until soft enough to permit of its being adapted to the cavity walls. In this process it must never come in contact with the open fiame. Various devices are employed for heating, such as porcelain trays to be held over the flame, or sand-bath. If overheated it is ruined. Ordinarily the instruments used are fiat burnishers which should be warmed and oiled. The cavity should have some retention form, and it is also well to coat the cavity walls with oil of cajeput or eucalyp- COMBINATION FILLINGS. 255 tus. Dr. Black remarks that these oils take strongly to cavity walls, and also slightly dissolve the surface of the gutta-percha, hence their value. The material is packed piecemeal into the cavity, or en masse, care being taken to insure thorough adaptation. One should guard against obtaining too much surplus, for gutta-percha does not lend itself so well to trimming and finishing as do other materials, although surplus can always be removed by the aid of a warmed burnisher. Or, when it has sufhciently hardened, it can be trimmed with thin, sharp trimming knives, always cutting from center to periphery. That gutta-percha has possibilities is undoubtedly true. It will in all probability be continued in use for some time to come. But, if personal opinion were not out of place, we might close this discus- sion by observing that the attitude of the dental world seems to the present writer to be that gutta-percha as a filling material for the entire cavity, all things considered, is distinctly altered since the virtues of copper oxyphosphate have been fully made known. COMBINATION FILLINGS. The term "combination fillings" has been made acceptable by usage, although it is not in all cases strictly accurate. The fact that no one material possesses all the virtues desired, together with other reasons, as, for instance, the greater ease with which particular parts of the same cavity lend themselves to particular ma- terials, have led to frequent indication of more than one material for the filling of the same cavity. A few of these will be taken up for discussion, although it must be remembered that endless combinations may be made, according to the necessities of the case, and the ingenuity of the operator. Platinum and gold are used together, chiefly for resulting color and density. Platinum is bluish silver-white in color. Its specific gravity is 21.46. The color of the combination varies between light and dark gray, depending upon the quantity of platinum used. This platinum-gold combination withstands attrition better than gold alone. For esthetic reasons it is indicated in cases when patients are of dark complexion. It is also desirable when more density is sought than gold alone can supply. Platinum-gold for filling is used in the forms of folds of both metals, of platinized gold folds, and of platinum and gold foil. It is best not to use it for the entire cavity, a surface of this composition being quite sufiicient. Generally speaking it is manipulated in the same manner 256 FILLING MATERIALS. as gold alone; but a little more care is called for in annealing and con- densing. That is, it is easily overannealed, and a small condensing- area plugger point should be used and moved only its own width each time, thus insuring thorough condensation. It may be worth nothing that this serviceable combination of platinum and gold has of late been replaced largely by the porcelain and gold inlays — the porcelain inlays chiefly in the anterior teeth, and the gold in many cases where great surface is to be restored for the purpose of resisting attrition. The properties of gold and tin have already been considered. Tin has been used to fill part of a cavity, the finishing of which is done with gold. Tin was largely applied in proximal cavities to cover the gingival wall, in the same manner as non-cohesive gold; but this opera- tion is practically discontinued, owing to what seems to have been a dissolution of the tin One method of preparing tin in this connection is to take it in sheet form, superimpose it upon a sheet of gold, cut to desired widths, and make into cylinders, as described under " Gold." A few operators use this combination in occlusal cavities in deciduous teeth, and in the gingival third of bicuspids and molars in the adult teeth to a limited extent. It is handled in every respect like non-cohesive gold. It is undoubt- edly true that this gold- tin filling may conserve certain teeth; but re- cent investigation has led to the improvement of amalgam and its consequent preferment over the gold-tin combination in many cases where the latter might formerly have served. Also, in the gingival portion of cavities there seems to be an increase in the use of non-cohe- sive gold alone; so that, on the whole, the outlook for this combination is not the most encouraging. The gold and amalgam combination is, at times, of great value, amalgam being used either to fill inaccessible parts of cavities, as below the gingival line, or merely to lessen the bulk of gold in very large cavities. In complex cavities it is often admissible to fill, for instance, a disto-occlusal cavity with amalgam, and the mesio-occlusal with gold, making a step into the amalgam. Gold and Cement. — Besides using the cement for its inherent vir- tues, it is also employed to lessen the bulk of gold in large cavities and in pulpless teeth. The amalgam and cement combination is used similarly to the fore- going. Cement is also used in amalgam operations to strengthen weak walls, in which case it practically becomes a cavity lining. Frail teeth can often be thus preserved for a remarkably long period. COMBINATION FILLINGS. 257 Cement and Gutta-percha. — Owing to the fact that gutta-percha is not soluble in the fluids of the mouth, it can be used in the gingival portion of proximo-occlusal cavities, cement being employed, since it is somewhat denser, for finishing the rest of the cavity. In general, it is not advisable to let metallic fillings rest upon gutta-percha, owing to lack of firmness in the latter; but a cement intervening will afford the proper support. It is difficult, if not impossible, to acquire from a text-book the art of filling teeth, be the text ever so explanatory and complete in detail. Theory must be supplemented by practice. To strike an even balance in this respect is a task of some proportions. In filling teeth, we imi- tate the work of others. Possibly we perfect a detail here and there, make a new discovery, or improve a method. The imitative aspect of the profession predominates, however. But this should not dis- courage us. All told, the world we live in is an imitative one, the absolutely new things discovered from decade to decade being very few indeed. Although his technique may have been revolutionized, the art of the sculptor has not changed since Phidias wrought upon the Parthenon or that unknown and remoter hand carved the Sphinx's features in the Valley of the Nile. The bases of the arts do not shift with the years; that which is of permanent value rests upon solid foundations like those of the Sphinx or the Pyramids amid their waste of unsteady soil. That which is good abides, and our own virtues may be measured ac- cording to the degree in which we show ourselves appreciative of the virtues of those who have laid our professional foundations. We might say that we have now reached a certain stage of perfec- tion in the preparation of cavities in teeth, and also in filling them with gold and other materials. Such advancement as has been made should be rigidly maintained. We should not, however, be content to rest upon achievements. We must keep the mind receptive to possibilities, and the hand pliant and supple to slowly evolved technical inventions. We have often seen and heard emphatic statements from operators to the effect that gold is the ideal and only fiUing in all cases, and that they use nothing else. Such statements are misleading to beginners who many times take them too seriously. Experience soon teaches that one cannot successfully adapt gold to all cavities. But the ques- tion, "what is the best filling?", implying that one material for all cases is possible, will often be heard from both scientific and unscien- tific people. Of course, the question cannot be answered as it is put. The whole of the foregoing chapter demonstrates this. An attempt 17 258 FILLING MATERIALS. at least has been made to elucidate the fact that any one of our materials is the best one for the special uses to which experience has taught us its properties have peculiarly adapted it. But supposing that we were actually limited to a choice of one kind of material. In that case we might, perhaps, choose what, in dental parlance, is known as the gold inlay — cemented into the cavity. A discussion of this appears in Chapters XIV, and XVII. This sup- position, although quite imaginary, tempts speculation. Each material should receive the highest possible attention from the operator as it comes into his experience. The object should always be to perfect oneself in the intelligent application and manipu- lation of materials; and this can best be done by regarding each, as it is indicated, as the ideal. This, indeed, it is, when once its prop- erties are found to harmonize with the needs of the case under treat- ment. In closing, perhaps it is well to reii^erate that increase in technical proficiency is stimulated if accompanied by growth in a general under- standing of the eternal fitness of things — an appreciation of propor- tions and harmonies, not only in our own specialized branch of the great world of science and art, but in all that we can, by industrious study, bring from that world within the range of our intellect. The whole world of artistic endeavor — literature, music, design, painting, sculpture — every division of the industrial and liberal arts — teems with lessons for the worker in so exacting and delicate a profession as that of dentistry. "It is all triumphant art, but art in obedience to laws." Dentistry itself, regarded in its true light, must, in the minds of intelligent operators, come to be regarded as not the least among modern arts and sciences. For one who acknowledges allegiance to this broader supremacy, the practice of our profession should, so far from narrowing a man's powers, continually expand them, and afford more and more intellectual satisfaction as he progresses towards the ultimate ideal of perfection. CHAPTER XIII. THE USE OF THE MATRIX IN FILLING TEETH. BY GARRETT NEWKIRK, M. D. Matrix — Definition of; Standard Dictionary: "That which con- tains and gives form to anything: as a plaster matrix for a cast." From mater (mother). The term is used in connection with descrip- tive anatomy, geology, biology; also applied to forms for stamping coins, medals, types, etc. Pronunciation, ma'-trix or mat'-rix. PL, mat'-ri-ces or ma'- trices. "In dentistry — a strip used as a dam in filling side cavities." It will be observed that the primary use of the matrix is that of giving form to a new structure; in nature to a growth, m art or me- chanics to a building or product. In general the term apphes to a product which is entirely new, a coin or medal or die. In dentistry we have a modified apphcation of the term in that the matrix is used for the restoration of pre-existing forms that have been to a greater or less extent broken down. The term "filling," as usually employed, does not fully express our meaning. It is commonly said by the dentist that he has "filled" a tooth, as if the tooth were only a hollow form, a capsule, a membran- ous sac, or a shell like that of a cartridge. The incongruity is ob- vious. Simple cavities in teeth may be "filled," and to this class of cases the term should be limited. What we are really called upon to do in most cases is to build up, to restore, the parts of a structure that have been lost. This we do with a substitute material, joining it as best we may to the remains of the natural organ. We may liken the teeth, if we will, to a double row of monuments. The relation of these monuments is such that they are inter-depend- ent. The loss of one is felt by others. Each is dependent on its fellows for its own true position and usefulness. These monuments come to us broken, with every degree of injury, demanding repair or substitution. Some are like trees in Africa that have been honey- combed by the insidious white ant. Some are like houses half torn away by a cyclone or an earthquake. They are in part ruins. The restoration of these monuments in proper form and of material to endure is no simple problem. No two are quite alike, their forms 259 26o THE USE OF THE MATRIX IN FILLING TEETH. are almost infinitely various. There arc no plane surfaces. The study is one of curved lines. The mechanical matrix is a temporary wall, placed for the support of building material that is more or less soft and yielding. A familiar example is that of a board employed in the making of a concrete walk, which holds the material in form till it hardens. The use of the dental matrix is fourfold: First, to serve as a wall of resistance, so that under pressure the building material may be thoroughly condensed and joined to the tooth. Second, to give the general shape of restoration, with a suffi- cient excess of material for finish and form. Third, in cases where plastic materials are used that require time for hardening and the matrix is kept in place till the new body has become fixed in its position. Fourth, to hold back the interproximal gum tissue, also the rubber dam, from the cervical border of a cavity, so that perfect contact of the building material at that place may be assured. MATERIALS AND FORMS OF THE MATRIX. The ideal material is that combining the greatest strength with thinness and spring temper. It appears to be the consensus of opinion that no other substance possesses so many excellencies as very thin steel. Ribbons of rolled or sheet steel, cut in suitable lengths, are best adapted for general use. For the first really practical band matrices made of thin steel, the profession is indebted to Dr. T. W. Brophy, who made up a "set" with an ingenious method of adaptation. These were placed on the market about the year 1886. Since that time many others have been brought out, generally under patent, though it is a question whether the original Brophy matrix did not cover the essential features of most of them. Tinned copper or German silver, rolled thin, are practicable ma- terials for band matrices, being easily adapted and soldered to fit spe- cial cases; for example, where the greater part of a molar or bicuspid crown is to be built up with amalgam, and where it is necessary to have the whole of the base encircled. In such instances it is not possible to obtain the best supporting matrix without making one especially for the case in hand. A good, practical, special band matrix may be made of the softer materials mentioned, as follows: A ribbon of proper width is cut half an inch longer than the measured circumference of the tooth. It is passed around and pinched together closely with pliers. A piece of MATERIALS AND FORMS OF THE MATRIX. 26 1 binding wire is wound several times round the matrix ends at the line of juncture, and twisted tight. The projecting ends of the matrix band are now bent back and down upon the band proper and the ap- pliance is ready for use. To do this last part neatly it is well to pass the band over the anvil point or any suitable form so that a small ham- mer may be used for the flattening. Nearly always a band matrix made for the case in hand should have its basal circumference smallest. If the form of restoration has been right the body enclosed holds the matrix fast, and it must needs be disjointed or cut for removal. A continuous band matrix to be used and removed entire must be of necessity too large in its rootwise circum- ference or too small at the crown. If large enough to provide for the proximal contact points it will project far into the interproximal space, leaving a gap between the cervical edge of the matrix and the tooth. Theoretically, we are told that this condition is to be overcome by use of a wedge at the cervical margin, but this, particularly with a steel matrix, is easier said than done. The material resists stren- uously at both points, and the resi: tance reaches all around the band. Usually it is neither accomplished nor attempted. The operator fills the matrix as it is, leaving the building material projecting and ragged at the base, often impinging on the soft tissues. It is difficult afterward to remove this projection with chisels, files or corundum strips without laceration of the gums and pain to the patient. Therefore, it is very important that the matrix in its introduction should pass close to the tooth, between the hard and soft tissues, never impinging on the latter. It cannot be forced down midway in the interproximal space and afterward wedged forward to place without injury. It should go to its proper position at the first. Any sort of band matrix, continuous or jointed, whatever may be its merits has one disadvantage. It comes short of the ideal in that it requires the use of two interproximal spaces. This involves often difficulty of adjustment with loss of time, both in the putting on and taking off; and the extra, second space is taken where all available room is needed on the side to be built up. It is an advantage to have the sound side of the tooth crowded against its next neighbor with nothing between them. This was long recognized as a consummation to be wished, but it seemed necessary that in general the matrix must be continuous around the tooth to insure a rigid support. It seems to the writer, however, that by the use of the "Ivory" matrices and their accompanying clamps, encroachment on the second space may be avoided in the great majority of cases. Just as the 262 THE USE OF THE MATRIX IN FILLING TEETH. "Perry" separator gets resistance on the inclined planes of the teeth instead of their disto- median axes, so the "Ivory" matrix clutch utilizes the inclined planes of the sound portion of the tooth to hold the matrix of restoration. The principle of the instrument is simplicity itself, and the mechanism highly ingenious. Of continuous hand matrices — i. e., those that go round the tooth far enough to occupy two interproximal spaces — there have been many Fig. 235. — Crenshaw's Matrix. forms invented and placed on the market; some of them patented. Cuts are reproduced here of the " Crenshaw," quite popular in the East, and the "Hiniker," in general use on the Pacific Coast. There are others, any one of which may be of value, when ruled by skillful hands. A form of appliance that has been widely advertised and recom- mended is that which we may style the "double" matrix, consisting THE "hand" matrix. 263 practically of two segments backed together and used for building up the disto-occlusal wall of one tooth and the mesio-occlusal of another at the same time. Certainly the principle of such an operation is not just right. Such restorations it seems to the writer should be made separately — one at a time; for the two teeth are not immobile — each moves slightly with any exercise of force upon it. The matrix should be firmly fixed to the tooth that is being operated upon. In the in- FlG. 236. — Hiniker matrix. sertion of the single "filling" the tooth and the material move together as one body, and the latter is in no wise disturbed. With two teeth at once, each possessing independent motion, this cannot hold true as the material is likely to be in some degree disturbed. THE "HAND" MATRIX. This instrument consists of a short, thin blade, continuous with a shank and handle. It is a valuable instrument in certain places where the band matrix is hardly applicable. It is specially useful for giving form to fillings of cement or gutta-percha, and not infre- quently for amalgam restorations. Such a matrix may be readily made by the dentist himself out of any discarded instrument that has a sufficient body of steel for the blade — a spatula or wide chisel for ex- ample. The secret of success in getting the desirable tough spring temper consists in persistent hammering with the avoidance of high heat. It may be added also that any other than the finest of files should not be used in dressing down the blade to the required thinness. For use, with everything in readiness for quick manipulation of the building material, the matrix blade is placed in position and held by 264 THE USE OF THE MATRIX IN FILLING TEETH. the left hand of the operator. It is seldom that an assistant can man- age it as well. The handle is given a strong twist, so that the rootward edge is held firmly up to the cervical margin of the cavity. The op- posite edge is held with equal firmness against the crown of the ap- proximating tooth. If either or both of the teeth are at all movable a considerable separation may be obtained by this steady twist of the handle. A sense of firm resistance, too, will be experienced while pressing the "filling" material home. The separation obtained should be equal at least to the thickness of the matrix, so that when it is withdrawn there will be sufficient fullness of material at the "con- tact" point. For restoring the disto-occlusal walls of a short crowned second molar, where it is sometimes impracticable to apply the rubber dam, and the work should be done quickly; and for incisors in making large restorations with cement, the hand matrix is a very useful instru- ment. A FEW DETAILS AS TO MANIPULATION. Success with the matrix often depends very much on previous preparation. Deep-seated cavities are frequently bordered by swollen, sometimes overhanging gums. It is nearly always better, after a free opening and more or less of preparation, to let these carry a filling of gutta-percha for some days. It is not unusual with the writer to have in one mouth several of these gutta-percha filled cavities waiting for the matrix and restoration. Before placing the matrix for an operation, if there is any doubt of its fitness it should be tried in tentatively, to ascertain whether it will pass as it should, close to the tooth wall and not upon the gum. Sometimes an ill-fitting matrix may be fairly adapted by pinching in the cervical edge with pliers. The Ivory matrices, however, are so shaped and may be so inclined in their introduction that they go to the right place easily in most cases. INTRODUCTION AND MANAGEMENT. It is commonly advised by experts that as a rule the matrix should not be completely tightened at the beginning, but only after the inser- tion of a third to one-half of the filling. Without doubt we may say that very many operators do not take sufficient pains with that same first one-third. Of amalgam altogether too much is likely to be placed in the cavity at the start. Smaller pieces should be introduced at first and thoroughly condensed with smooth instruments all along the cervical wall and its junction with the matrix. This takes so much time that often with quick-setting amalgam a second and third "mix" may REMOVAL. ' 265 be required to complete the operation. Sometimes with extra dry alloy one may use a mallet with good effect, in addition to hand pressure. In the second half or last third of the filling, whatever the material employed may be, enough force should be exerted against the matrix to induce separation of the teeth by a space not less but more than the thickness of the band. If the teeth have been prepared by gutta- percha wedging, as above suggested, this necessary crowding apart is an easy matter. As stated before, there ought to be an excess of the new material to allow for final shaping, and there ought to be like- wise a separation of the teeth beyond the normal at the completion of the filling. This will permit the final contact point to come slightly below and away from the border of the occlusal surface, otherwise it will be a mere edge continuous with the occlusal surface, and not the rounded, finished knuckle of nature's plan. There would be an improvement at this point, no doubt, if the operator would take the pains to make in each matrix a sufficient con- cavity with contour pliers, to bring the filling nearer the ideal form. As it is, with any common form of matrix, the filling as the band leaves it shows only a straight profile from the cervical to the occlusal border. The contoured matrix, however, used for a plastic filling could not be removed at once without disturbing the form. It would need to re- main till the material had set. REMOVAL. With amalgam there are, as we know, advantages to be gained by leaving the matrix in siti* till the material has become hard; indeed, it is very necessary to do so in cases where reconstruction has been extensive and the basal support relatively weak. But, on the other hand, there is something to be gained by immediate removal. This is one of the advantages of an open matrix like the "Ivory." When the clutch is loosened it "lets go." It is readily straightened, being flexible, and touches the tooth or filling only at the point of contact. With the slightly oiled surface a band should always have it is easily removed by gentle manipulation. Then, with a properly shaped blade, half knife, half burnisher, a trimming and close condensation of the material may be made all along the edges. I believe that perfect bor- ders can be made in this manner with greater certainty than is possible otherwise. EMPLOYMENT OF THE MATRIX FOR GOLD RESTORATIONS. We know what the bevel of a margin should be for the reception of gold. We know that for the proper condensation of gold over such 266 THE USE OF THE MATRIX IN FILLING TEETH. a margin the instrument should have free play; and we know that it is well to have visual as well as mechanical access to the area involved. There is no denying that the matrix does shut off vision along the very lines where seeing is desirable. If we permit a loose adjustment of the matrix in order to see the margins it is of little use. It is likely also to crowd upon the gum tissue, to draw the edge of the dam from the tooth and induce leakage. If closely adjusted, the matrix forms with the beveled margin a sharp, acute angle, into which the gold must be forced accurately and condensed, else there is left an imperfect line of union. We cannot be as certain with as without the matrix that the gold is being adapted accurately at every point. Undoubtedly there are operators who have learned with much of patience and experience to obviate the risk; who can apply the matrix over a deep-seated cavity and make a good restoration from start to finish. But such operators the writer believes to be exceptional. It is a fact of experience that we are often called on to renew or repair fillings that have been so inserted which have failed at the cervical or cervico-lingual or cervico-labial borders; and we find others that are spongy or pitted or grooved in those places. Let it be understood, however, that after a substantial body of gold has been placed along the wall and angles of the cavity, then the matrix may be of service as a guide to the general form of building, especially for the full extension and thorough condensation of the "knuckle" at the contact point; and possibly the work may be done more rapidly. If one is determined to take the risk, whatever it may be, of using the matrix "from start to finish" for contour restorations, he must familiarize himself with the properties and manipulation of non-co- hesive gold. It is the chief dependence of successful operators for the basal third or half of the restoration. GUTTA-PERCHA FILLINGS. For the insertion of these the matrix has a well-defined use. Aside from those cases wherein it is necessary to crowd away the gum for a subsequent operation, the margin of a gutta-percha filling should be carefully made like any other. Patients often suffer discomfort and sometimes real injury from carelessly made gutta-percha fillings. It is better to make a filling of good form to begin with than to crowd in an ill-defined mass to be trimmed up afterward, and for this purpose the "hand" matrix is usually well adapted. CHAPTER XIV. INLAYS. BY C. N. JOHNSON, M. A., L. D. S,, D. D. S. The Principle. — To repair a carious or abraded cavity in a tooth by the inlay method the operator adapts a piece of heavy foil, either platinum or gold, to the cavity so that it fits perfectly, thus reproducing the form and outline of the cavity in metal; and in the matrix so formed, removed from the mouth, he builds a filling of porcelain or gold and cements this in the cavity. In the more recent developments in gold inlay work a wax model is made in the cavity, and this is reproduced in gold. The principle is different from that of the ordinary filling, the latter being adjusted piece by piece into the cavity in the tooth, the entire operation being performed in the mouth; while with the inlay much of the work is done outside the mouth and without the necessity of the patient's presence. This is a very great advantage of inlay work and has led in a large degree to its popularity. The relief from the tedium of long and sometimes painful sittings has been a source of great satisfaction not only to the patient but to the operator as well. There is less nervous tension and altogether a greater measure of comfort in doing inlay work than in such oper- ations as large gold fillings, and this phase of the subject has appealed very strongly to patients. INDICATIONS FOR THE USE OF INLAYS. That inlays have become an important factor in reparative proc- esses in operative dentistry there can be ncJ question. There is still some difference of opinion as to the precise range of their applicability, but for certain well-defined cases their utility is no longer in doubt. It must, therefore, be apparent that no dentist can practice to the best advantage for himself and his patient without an understanding of this work. There are many cases of aff'ected teeth that can be better preserved by this than by any other method. In cases of extensive decay it may frequently be made to save a tooth which otherwise would be condemned to crowning, and on general principles the longer a tooth can be saved without a crown the better it is for the patient, 267 268 INLAYS. From the nature of their method of manufacture inlays are restricted in their use to cavities which will admit of the matrix or wax being inserted and removed without distortion, or cavities which may be made of such a form without an unwise sacrifice of sound tooth tissue. Porcelain inlays are indicated chiefly in cavities exposed to view in talking, laughing, or singing. It should be the highest aim of art in dentistry to conceal the evidence of our operations from public view, and the conspicuous display of gold so frequently seen in the anterior teeth of patients speaks of a lack of taste which is something of a reflection on the profession. Fortunately this display is less prominent than formerly, and this in large measure is due to the introduction of porcelain inlay work. With porcelain an operation may be made which is not conspicuous at conversational distance from the patient, and in some instances the porcelain may be shaded to match the enamel so perfectly as to defy detection even on reason- ably close observation. This is a great step in advance so far as the art side of our calling is concerned, and every dentist should equip himself to take advantage of it. But this work has its limitations which should be recognized by every conscientious operator. The physical characteristics of porce- lain are in some respects very much against its extended use, particu- larly in positions where the stress of mastication comes forcibly upon it. Porcelain is brittle and will fracture easily. It is therefore contra- indicated in cases where the filling must be made with thin margins or in small bulk. It is true that in the anterior part of the mouth where esthetic considerations are very important it is frequently justifiable to take some chances of its fracture and place it in positions of prominent exposure even with some risk of failure. Patients are often willing to take this risk for the sake of the improved appearance over any kind of a metal filling, and where there is a perfect under- standing between operator and patient as to the possibilities of failure porcelain may be given a rather wide range of application in the anterior teeth. Porcelain inlay work has not been sufficiently long in general use to afford the necessary data upon which to base reliable judgment as to its probable permanence, and in many of these cases where great risk was apparently taken the service of the inlays has been surprisingly satisfactory. It may also be stated that in many other cases where the same care has been exercised in their manu- facture, and where conditions would seem to favor their utility they have proved a grievous disappointment. It is this element of uncer- tainty with inlays which has made many of our conservative practi- INDICATIONS FOR THE USE OF INLAYS, 269 tioners look with disfavor upon the work, and yet their demonstrated utility in so many cases is sufficient to argue strongly in their behalf. It is probably true that much of the failure has been due to imper- fect methods of manipulation and to a lack of knowledge of the under- lying principles of the work, as well as to faulty technique in carrying it out. Another uncertain factor has been the cement. This material has proved itself peculiar in its behavior under various conditions and some of its peculiarities have not been well understood. In addition to this, much of the cement used for inlay work in the past has been made for fillings and for cementing crowns without regard to the peculiar requisites for inlay work. Neither have the correct principles of cavity preparation for inlays been generally recognized or put in practice. In short the work has had to pass through the experimental stage of a new line of effort and has suffered accordingly, but these factors of failure are rapidly being eliminated and we may confidently look forward to more assured success since the principles are being better understood and the technique systematized; though with porcelain inlay work it must not be forgotten that it will always have the one serious limitation of friability of the material itself. Gold inlay work has a much wider range of usefulness so far as serviceability is concerned than porcelain on account of its great strength, and it should be used quite generally wherever inlay work is indicated in places not exposed to view. Gold may be made to protect frail walls of enamel if necessary and the material itself may be extended into thin margins without danger of fracture. To specify the particular classes of cavities where inlay work is indicated and draw a distinct line of demarcation between the indi- cations for fillings and inlays is difficult, owing to the varying con- ditions which are presented in different cases. The preference of the patient must sometimes be considered, though it is not well to allow a whimsical prejudice to influence the operator to do a certain class of work under conditions where it is manifestly contra-indicated. It may be said in general that porcelain inlays are indicated in all cavities exposed conspicuously to view in cases where esthetic considerations are very important, such as cavities in the labial or buccal surfaces of incisors, cuspids and bicuspids, cavities in the proximal surface of those teeth where there is much exposure, and in contour operation involving two surfaces where a display of gold would be objectionable In recent years the use of silicate cements has somewhat displaced porcelain, and the tendency seems constantly in that direction. The 270 INLAYS. improvement in the silicates, and the more satisfactory appearance of the margins of such fillings over porcelain inlays has led many opera- tors to practically discard porcelain in their favor. There is no question that a more artistic filling may be made with the silicates than with porcelain, but so far as wearing properties are concerned the former cannot be compared with the latter. It is hoped that with the constant improvement being made in the silicates we shall eventually have a plastic material which will be sufficiently permanent to render the somewhat difficult technique of making porcelain inlays less necessary. Gold inlays are indicated in large restorations in bicuspids and molars, in cavities far back in the mouth where the problem of insert- ing an ordinary filling is difficult, and cavities in the buccal surfaces of molars where the decay has extended under the free margin of the gum. Employed in these cases gold inlays are very useful and may be given a wide range of service, but this will still leave a large class of cavities where the ordinary filling has its legitimate field and where no inlay can do equal service. CHAPTER XV. PREPARATION OF CAVITIES FOR INLAYS. BY C. N. JOHNSON, M.A., L. D. S., D, D. S. When inlays were first introduced the general impression given the profession that the adhesive properties of cement could be relied upon to hold the inlay in place irrespective of much depth to the cavity led to the formation of cavities too shallow^ and vi^ith insufficient atten- tion to the principle of mechanical anchorage. Inlays should be anchored upon the same general mechanical plan as fillings, the only difference being in the details. It will of course be recognized in the beginning that cavities for inlays must be so formed that the matrix or wax may be lifted from the cavity without distortion, and this idea being prominent in the mind of operators caused them in many instances to make the walls of their cavities too flaring, with the orifice much wider than the interior. This resulted in attenuated edges to the inlay and frequently to a lack of definiteness of form, leaving the cavity more or less saucer-shaped. This is wrong in principle and has quite generally proved a failure in practice. Cavities should be made with some depth and with walls so formed that the inlay will remain seated without tilting or rocking under pressure even before it has been cemented. In opening up cavities it is true that there are many cases where the orifice must be quite widely extended to admit of entering a matrix or wax into the cavity and removing it. This often involves cutting much sound tooth tissue, particularly in proximo-occlusal cavities in bicuspids and molars, where the decay in the proximal surface may have ex- tended much wider bucco-lingually in the gingival region than it has nearer the occlusal surface. It will be seen at once that to fit a wax model to such a cavity it must be extended bucco-lingually very freely at the point where the proximal surface joins the occlusal to bring it on a line with the cavity further rootwise. The practitioner who purposes using inlays in these cases must have the will to cut quite extensively, and there are many instances where the loss of sound tooth tissue is so very great that the discriminating operator will decide upon inserting a filling instead of an inlay. This is one factor 271 272 PREPARATION OF CAVITIES FOR INLAYS. in the choice between inlays and fillings which has not received suffi- cient consideration. While it is true that in the preparation of cavities, whether for inlays or fillings, we are frequently called upon to remove sound tissue for better access to the cavity and to establish marginal outlines at points where recurrence of decay will not take place, yet it is unjustifiabfe to sacrifice large portions of sound tissue in locations of practical immunity from decay in order to bring the cavity within the requirements for inlay work. In many of these cases a filling may be inserted to better advantage and with less injury to the tooth. One cardinal principle in the formation of cavities for porcelain inlays is that they should be so shaped if possible as to leave no thin margins to the porcelain. A thin margin usually means a fractured margin in a short time. With cavities for gold inlays the exact opposite is true. One of the chief virtues of gold inlays is that the enamel margins may be freely beveled and the gold allowed to lap over them — a relatively thin layer of melted gold being sufficiently strong for ample protection to the enamel. It is with this idea in mind that the following detail of cavity formation for the different classes is sug- gested. Cavities in the labial surfaces of incisors and cuspids, and the buccal surfaces of bicuspids and molars. The first essential in the preparation of these cavities is to open the cavity freely by breaking down all enamel undermined by decay. The axial or pulpal wall should be made perfectly flat so that the inlay will have a definite seat to rest upon. This is conveniently done with an inverted cone bur stood with its end looking toward this wall, and carried laterally across the floor of the cavity. There should be an angle formed between the axial wall and the surrounding walls, not a perfectly right angle so as to leave the surrounding walls parallel, but very nearly so. If these walls were perfectly parallel it would manifestly be impossible to fit a matrix and remove it, but the nearer they approach to this the more securely will the inlay be anchored, and the less neces- sity for relying on the cement as an adhesive agent. Cement should be used in the capacity of a sealing material between two joints and not as a glue to hold the inlay to the cavity. In short the cavity should be so formed that there shall be some frictional retention against the surrounding walls, the inlay in many instances going to place with a snap. When cavities are formed along these lines there will be less trouble from inlays dropping out. It might be imagined that the fitting of a matrix to such a cavity would be very difficult but this is found in practice not to be so, and PREPARATION OF CAVITIES FOR INLAYS. 273 even if it did slightly complicate this part of the operation it would be justifiable on account of the greater security of the inlay. There should be no beveling of the enamel margins for porcelain except as the slight divergence of the surrounding walls at the orifice of the cavity forms a bevel. In the use of the inverted cone bur for forming the axial wall if the sharp angle of the bur should undercut the surrounding walls they may be trued up wath a chisel or with a fissure bur stood with its end looking toward the axial wall and cut- ting with the side of the bur. The outline of a cavity formed as just indicated is shown in the two sections of an incisor, Fig. 237, longi- tudinal, and Fig. 238, cross-section. In bicuspids the form of the axial wall is sometimes different from this on account of the difference in the form of the tooth. If the axial wall were cut perfectly flat in some cases of extensive decay it might result in exposure of the pulp and so it should be given a convex Fig. 237. ' Fig. 238 Fig. 239. Fig. 240. form as indicated in the cross-section of a bicuspid, Fig. 239. This form facilitates the firm seating of the inlay fully as well as the flat form, and in some instances furnishes a more secure anchorage. In extensive penetration of caries where the cavity runs under a strong wall of overhanging tooth tissue and it is deemed undesirable to cut this wall entirely away, it may be permissible to excavate the cavity perfectly and fill the undercut with cement. After this has become hard the cavity may be prepared as usual. This practice is not often feasible on account of the fact that ordinarily when decay undermines a wall it does so in such a way as to weaken it beyond the possibility of retaining it with safety. Upon broad surfaces such as the buccal surfaces of molars we frequently find decay running along over a considerable area with little penetration into the tooth, and in these cases if the cavity is formed on correct mechanical lines with flat seat and proper angles it need not be made very deep. But an inlay for such a cavity should be of strong material and it is usually best in all buccal cavities of molars to insert gold inlays in preference to porcelain. 18 2 74 PREPARATION OF CAVITIES FOR INLAYS. Simple cavities in the proximal surfaces of incisors and cuspids. These cavities must be opened sufficiently to the labial or lingual to admit of fitting the matrix, and it is therefore necessary to cut away one of these walls quite freely; though the ample separation of the teeth in advance of the operation will in some measure dispense with this necessity. The same provision for seating the inlay firmly in place should be made in these cavities as in others and the axial wall should be made as flat as possible. If the labial wall has been cut away and the lingual wall remains standing with sufficient integrity to admit of it being left, there should be an angle formed between it and the axial wall, and even where the lingual wall must' be removed it will be found possible to make a point angle in the gingivo-linguo- axial region. The gingival wall should be made at nearly right angles with the axial wall and almost parallel with the incisal wall, which should also join the axial wall at an angle, so that the inlay will lock between the incisal and gingival walls as if in a box. Fig. 240 illustrates the labial surface of an incisor with the marginal outline of the cavity indicated, and the dotted lines showing the interior form of the walls. In cases where there has been much breaking down of the lingual wall with a strong labial wall standing, the cavity should be opened mostly to the lingual and the inlay inserted from this direction. In these cavities an angle should be made in the gingivo-labio-axial region so as to form a flat seat of resistance at this point, which will receive most of the stress brought to bear upon such an inlay. Cavities in the proximal surfaces of the anterior teeth involving the incisal angle. These cavities present a more difficult problem for porcelain to meet than any of those where porcelain inlays are indicated, and yet their exposed positions often call for this kind of restoration. It is therefore necessary to study very carefully the forms that shall be given these cavities for the most secure anchorage and the greatest strength to the porcelain. The operator must individual- ize his cavities and take advantage of every possible opportunity presented by the peculiarities of the case to gain depth to the cavity and bulk to the inlay. It will usually be found that to gain security of anchorage some form of step must be made in the incisal region, and yet there are certain cases which do not lend themselves readily to this method of treatment. Ordinarily the step is made by cutting across the incisal edge at right angles to the proximal portion of the cavity making approximately an L shape to the inlay, but sometimes it is not ex- PREPARATION OF CAVITIES FOR INLAYS. 275 pedient to cut away the angle of the enamel in this manner. This is particularly true of those cases where the decay has involved the lingual surface far in advance of the labial in upper incisors leaving little tissue in which to form a step. It is also true in some instances where there has been a simple proximal cavity of shallow depth in either an upper or lower tooth and the incisal angle has fractured off following a check in the enamel leaving a clean sound surface of tissue along the axial wall with the enamel in perfect condition in the incisal region. These are cases which do not call for much incisal exposure to stress and it would seem too radical a procedure to cut away the incisal enamel, besides increasing the exposure. If the teeth in these cases are well separated a cavity may be prepared by cutting a shoulder in the axial wall looking toward the incisal and about one and one-half millimeters from the incisal edge, as indicated in Fig. 241. This should be supplemented by a rather deep and strong Fig. 241. Fig. 242. Fig. 243. anchorage in the gingival region, and if the teeth are sufficiently separated the inlay may be slipped into place laterally. This form of anchorage is of course not the strongest from a mechanical point of view where great stress is exerted on the inlay, but in a somewhat close observation of many cases in practice it has proved sufificiently satisfactory to recommend its use in the class of cavities indicated. Where the step anchorage is employed it is usually best to shorten both labial and lingual plates of enamel at least half way across the incisal edge (Fig. 242, labial view) , though this is not invariable. Some- times the labial enamel may be left standing in upper incisors provided sufficient bulk can be given the porcelain in the step. In either case the lingual plate should be cut away more than the labial, and this is particularly true near the termination of the step. At this point the lingual aspect of the step should be made to dip rootwise quite per- ceptibly to provide an interlock to the inlay (Fig. 243, lingual view). Care should be taken that there are no thin edges left to the inlay in any of its outline and this is accomplished by cutting the enamel with little or no bevel. It is also possible in some instances to add 276 PREPARATION OF CAVITIES FOR INLAYS. to the bulk of the porcelain in upper teelh, and thus increase its strength in the region of the step, by building it fuller lingually than the tooth originally was. The relation of the lower incisors will often admit of this and in some instances it is advisable to slightly shorten the lower tooth to give the needed space. In the gingival region provision should be made for a broad seat- ing of the inlay. The gingival wall should be flat and as wide mesio- distally and long labio-lingually as the available tooth tissue will permit. No undercutting is of course permissible but the labial and lingual walls may be made to extend from the gingival wall in a very nearly parallel direction. This will give a box-like form to the cavity in this region and result in security to the inlay when cemented. Cavities for the restoration 0} incisal tips. It is sometimes found practical where the incisal portion of an anterior tooth has been marred by faulty development, so as to be dwarfed and unsightly, to restore the end with porcelain. It is also possible in some instances Fig. 244. Fig. 245. Fig. 246. Fig. 247. Fig. 248. to do this where the incisal portion of an incisor has been broken off by a blow, though the cavity preparation for the two is entirely differ- ent. In the first instance there is usually a thin projection of tooth tissue standing on the end of the tooth as if the enamel had been stripped from it, and this may be utilized as a tenon over which the inlay may be mortised (Fig. 244, longitudinal section of an incisor mesio- distally, Fig. 245, longitudinal section labio-lingually). The shoulder where the perfect enamel begins and against which the inlay is fitted should be cut at right angles to the tenon, and the latter so trimmed that the matrix may be fitted over it and removed without dragging. In the case of a fractured tooth leaving the end flat the problem of anchorage is greatly complicated. Retention must be gained by drilling into the fractured surface and the danger of approaching the pulp is always a factor in the case. If the fracture has not occurred far rootwise a groove may be made running mesio-distally across the tooth (Fig. 246), shallow in the center to avoid the pulp and deeper at each extremity where it passes mesially and distally of the pulp PREPARATION OF CAVITIES FOR INLAYS. 277 (Fig. 247). If the fracture has extended so near the pulp as to reach a thick part of the tooth so that the labio-lingual width of the fractured surface will permit it, two grooves may be made, one to the labial and one to the lingual of the pulp, and these should join the labio- lingual grooves at either side (Fig. 248). All grooves for this purpose should be made flat at the base and as broad and deep as the tissue will permit. Cavities involving the proximal and occlusal surfaces of bicuspids and molars. These complex cavities are usually better managed by the use of gold inlays than porcelain and the detail of cavity formation herein suggested is in accordance with this idea. The most serviceable of all inlay work is in connection with the large restorations frequently necessary in these cases, and the operator should study carefully the possibilities of inlays in those positions in the mouth where the diffi- culty of inserting large fillings of foil has frequently proved a serious physical and nervous tax on patient and operator. As has already been intimated the preparation of these cavities involves a wide extension bucco-lingually of the proximal portion of the cavity as it reaches the occlusal, and wherever a step can be made in the occlusal surface at right angles to the proximal the chief reliance for anchorage should be in this step. This is particularly true of bicuspids where the bulk of tissue for anchorage in the proximal region is not so great as in molars. The step should be given a dove- tailed or interlocking form so as to avoid any possible tipping of the inlay and this may usually be accomplished in one of two ways, depend- ent upon the form of the tooth. Where the cusps are prominent and the depressions between them deep it will usually be found that there is an appreciable concavity at the termination of the step most remote from the proximal cavity, and in this instance the step at this point may conveniently be made much wider bucco-lingually than it ■ is midway between the cusps. The effect is to dovetail the step portion of the inlay against any possibility of tipping (Fig. 249). Where the occlusal surface is more nearly flat with little prominence of the cusps and almost no depression between them, the interlock may be secured by deepening the termination of the step rootwise as shown in Fig. 250, a mesio-distal, longitudinal section of an upper bicuspid. The same provision for a flat gingival wall in the proximal portion should be made as in incisors, and the buccal and lingual walls should extend from the gingival in nearly a box-like form. If the cavity is prepared in this way and the inlay properly fitted it will snap into place whh a frictional retention against the walls which adds greatly 278 PREPARATION OF CAVITIES FOR INLAYS. to the sense of security. Such an inlay will not rock or tip on pressure even before it has been cemented. In case the enamel on the occlusal surface leading from the cavity is perfect and it is deemed not advisable to cut into it to form a step, retention against tipping may be secured by making the cavity slightly wider bucco-lingually at the axial wall than it is at the dento-enamel junction (Fig. 251, cross-section of a lower molar). This forms a dove- tail and in cases where there is sufficient bulk of tooth tissue to work on it may be done without weakening the walls. It is of course apparent that the only direction in which a model or inlay can be removed from such a cavity is toward the occlusal surface. In other cases where the dentin is so involved in the occlusal region as to leave the axial wall greatly concave and no foundation for a step, an interlock may be gained by shortening one of the cusps and build- ing the inlay over it (Fig. 252, lingual surface of a bicuspid). It will be found in these cases that the dentin is quite extensively dissolved Fig. 249. Fig. 250. Fig. 251. Fig. 252. from under the enamel as it arches over the cusp and the wall is made more secure by cutting down the cusp and protecting it with gold. This may be done with both cusps if necessary where there has been much undermining of the enamel, and even this extensive restoration may frequently be necessary without the pulp being involved. These are the cases which heretofore have been quite generally consigned to crowning, but an inlay restoration such as just indicated where" even the entire occlusal surface is reproduced in gold is in every respect preferable to a crown. And this is not only true of these cases but of others still more extensive where the mesial, occlusal, and distal surfaces are involved in the same tooth, requiring a restoration of all three with the gold overlapping the buccal and lingual walls. (Fig. 253, lower molar, buccal surface.) The general form of the cavity in such cases must of course be governed by the conditions presented. Weak or overhanging enamel should be ground away quite freely for the double purpose of securing a firm foundation and for thoroughly opening up the cavity. The PREPARATION OF CAVITIES FOR INLAYS. 279 principle of the flat seat for the inlay to rest upon should be maintained as largely as possible, because of the necessity for security against dislodgment under the severe stress of mastication to which such restorations are subjected. The enamel margins should be beveled away quite freely with the utmost confidence that the gold will form an adequate protection to them. _.^ ,.-^, In case the pulp is dead advantage may be taken of / ^^'^^^--^ \ the pulp chamber for anchorage after the canals have been filled, but in the event of this additional anchor- age not being required the chamber may be filled with „ cement and this leveled to form a flat seat for the inlay. ' ^/^ '°^' Cavities in the occlusal surfaces of bicuspids and ^^°' *53- molars. It is a very rare condition which calls for an inlay in the occlusal surface of a bicuspid unless it involves some other surface. A simple occlusal cavity can be more judiciously managed with a filling than an inlay, and it is only in molars with cavities of appre- ciable extent where it is judicious to make occlusal inlays. The preparation of these cavities is not com- plicated. The floor or pulpal wall should be made flat so as to be at right angles to the stress of mastication, and the surrounding walls should be nearly parallel to make a mortised effect to the inlay (Fig. 254, section of a lower molar). In cases where there has been an extensive involvement of the tissue undermining the occlusal enamel leaving it frail, it may be ground down slightly past the marginal ridge and the entire occlusal surfiace reproduced in gold (Fig. 255). The technique of cavity preparation for inlays is quite simple and the operation altogether more accept- able to the patient than for fillings. There is no necessity for applying the rubber dam and this to many is a great relief. The cutting is mostly done with chisels, excavators, and such rotary appliances as stones, wheels and disks. The only necessity for the use of burs in large cavities is in sharpening up some of the line angles, and to flatten the walls left rounding by the stones. The fact that the grinding may be done under moisture reduces the pain to the minimum, and this is a great recommendation for this class of work. CHAPTER XVI. THE PORCELAIN INLAY. BY W. A. CAPON, D.D.S. The eventual success of porcelain as a filling for teeth depends upon thorough consideration of two primary principles, viz., founda- tion and adaptation. The first term applies to cavity preparation, the second to matrix formation, and they are closely allied in im- portance. The consideration of the former by a preceding chapter allows the matrix to become my first topic. METHODS There are two methods of making a matrix called the "direct" and "indirect" and either can be used according to the desire and training of the operator. The indirect method consists of taking an impression of the cavity with modeling compound or a hard wax and making a model of some hard material such as amalgam, cement or low-fusing metal. There are many adherents of this mode of making an inlay who claim equal results with the older and more popular method of working di- rectly on the natural tooth. It is a debatable point which is best settled by thorough trial by the student. The advantage claimed is that in- la,yr are made by assistants and a series of operations carried at the same time without delay. In the writer's estimation there are disadvantages that more than offset what is claimed, viz: A greater cutting of tooth substance to allow an impression material to accurately portray the cavity edges. The difficulty of reproducing with any material a cavity edge as per- fect as the natural tooth enamel. The amount of technique required before a matrix can be made, and finally the passing to a subordinate the astistic and most important part of the operation. However, that may be a motive for many who enthusiastically claim the indirect method as being preferable. The writer's many years' experience has proven the direct method of taking the matrix to be simpler and more expeditious and therefore presents that procedure in detail as follows: 281 282 THE PORCELAIN INLAY. The metals used for matrices in porcelain inlay work are made of either platinum or gold foil and their respective value for this purpose is usually an argumentative point whenever the subject of high or low fusing porcelain is dis- cussed. Adherents of high fusing porcelain have no choice except platinum while the advocates of lower heat material can use either gold or platinum. Platinum has for its recom- mendation adaptability and stability of form, together with its great resistance to high heat, thus dispensing with the necessity for an investing material to keep its form. The vir- tue of gold is its ductihty and easy adaptability to floor and walls of cavity, but this very softness in the majority of cases renders an investment necessary, thus precluding any trial fitting or reburnishing which is of so much assistance espe- cially to the beginner. It being my intention to describe the use of high fusing porcelain particularly, I have no alternative of a choice of metals for a matrix even if so de- sired, and will consider the subject from this point of view. The difficulties connected with making a matrix are ^ somewhat regulated by the position of the cavity and the amount of working space in its immediate vicinity, therefore it may simplify the subjects to divide them into three grades as , follows: V. T. Labial and buccal cavities. 2. Proximal cavities in anterior teeth with lingual surface not in- volved. Gingival cavities curving well to the proximal. 3. Proximal cavities in incisors involving lingual surface, prox- METHODS. 283 Fig. 257. imo-incisal restorations, distal surface of cuspids, mesial surface of first and second bicuspid and first molar. Sufficient space between teeth is imperative with this class of operations because porcelain is unyielding and cannot be forced to position without risk of chip- ping edges. The matrix must come from the cavity without change of form and frequently there is plenty of space for the inlay when finished, but owing to necessary excess of matrix ma- terial it locks itself when there is apparently sufficient space. The impression of the cavity or matrix is made with gold foil No. 40 or pure platinum gauge i/iooo in. or .001 in. thick- ness — thoroughly annealed. ■ In these days of inlay requisites this material is kept ready for use by all dental dealers, but it should not be handled much before using and it should be pure. If greater softness is required give it a high heat in the ||| furnace muffie. I emphasize the word pure because iridium |||| and platinum are naturally alloyed and as iridium is the most ||| difficult metal of the platinum group to eliminate, this fact may ||| account for the variance in softness in different purchases. The proper thickness of the metal has been a point of considerable discussion, but it is now generally conceded that i/iooo is the correct thickness for most operations. It may sometimes be |l|i slightly heavier, but never thinner. Many argue that if i/iooo is good 1/2000 must be better because of the minimum amount of metal at the edges, forgetting or not knowing that burnishing reduces thickness to a lighter gauge. Labial cavities in central incisors are in the first grade, there- fore a detailed description will be more easily understood. The foil is cut sufficiently large to allow holding against ad- joining teeth, and somewhat diamond shaped, the extreme ends being held firmly by the first and second fingers of the left hand, leaving the right hand free to use the instruments for burnishing. My preference is for few and simple instruments such as HMI two or three sizes of rubber tips and some amalgam burnishers. Special instruments such as those designed by Dr. W. T. Reeves, and Dr. C. N. Thompson have extensive use and fulfill the require- ments desired. (Figs. 256 and 257.) Dr. Jenkins presents new bur- 284 THE PORCELAIN INLAY nishers made of glass. It is claimed that the metal is forced to position with less danger of tearing because of the absolute smoothness of contact surface. Whenever possible it is well to give the outline of the cavity by the rubber points or spunk held by ball tipped pliers pressed firmly over the cavity, stretching the metal with safety, then rotating a ball pointed instrument with gentle pressure, commencing with a large size, following with smaller ones until the metal is fairly well adjusted; then use small pieces of spunk, chamois skin or camphor, packing tightly. It is now safe to use the other hand and with it hold the matrix in place with a blunt instrument pressing the packing, then burnish edges thoroughly, but not roughly for fear of tearing. A break on the cavity edge means a new mold while one at the bottom of the matrix is of no moment. Remove spunk or whatever has been used as an assistant and carefully release the matrix which is now ready for the porcelain. If inadvertently there is an undercut in the cavity sufficient to lock the matrix, gently force it out, then re- place and reburnish the edges, not touching the interior, thereby making a change of the cavity unnecessary. The making of a matrix for a proximal cavity requires more skill and practice. The foil should be carried well above the gingival margin of the cavity and if the gum is even with it the edge of the metal should be turned to look tow^ard the proximating tooth and lie over the gum, giving a sure working surplus. Rubber points are not much used in these places, therefore take the flat end of a bur- nisher and press across the cavity edges gently, forcing the foil to posi- tion assisted by small squares of spunk. The burnishing and general procedure is the same as for a simpler cavity except that usually surplus foil is in the way if both labial and lingual surfaces are burnished flat to the tooth, therefore if drawing from the labial side, have the lingual surface approximately burnished, take out and cut surplus off, then replace and get outline more perfectly and thus save a probable twisting of the matrix caused by an excess of material. If the cavity has greater presentation toward lingual surface the same rule is applied. Many practitioners suggest that much assistance can be gained by holding matrix in place with rubber dam, gold beater's skin, or china silk, and burnishing the matrix through these materials. Some years ago Dr. Allen, of Kansas City, added gum-cam- phor to our equipment as an assistant in making a matrix and it is most excellent when used properly, but many operators make the mistake of using it everywhere, forcing it in the cavity when the METHODS. 285 matrix is unprepared, and the result is an aperture from edge to edge therefore it is well to have the cavity walls fairly outlined before using it. It is of most value in labial cavities or where there is plenty of space to permit of easy withdrawal. After the matrix is made it is recom- mended that it be thoroughly cleansed by placing it in alcohol which will cleanse it of saliva or blood if camphor packed. The action of alcohol will dissolve the mass so it will drop out. Passing it through an alcohol flame will burn it out leaving no residue which is one of the recommen- dations for using this material for packing; however, if gold is being used it is safer to use alcohol alone. After the matrix is cleansed clasp the surplus portion firmly with a pair of straight fine pointed tweezers and fill the mold with the shade of porcelain chosen, which is mixed with clean water or alcohol or a mixture of both and applied with a fine pointed sable pencil brush and the little lump of stifif porcelain is gently patted or jarred to place. The edges of the cavity form are traced clean with point of brush and the embryo inlay is laid face down on absorbent paper or a clean napkin which abstracts the surplus moisture. Dusting dry porcelain over the moist surface is also recom- mended. I prefer applying the first piece so dry that it is difficult to pick up with the brush. It is at this point that the advantage of a sable brush is noticed because it holds a point without drooping while camel's hair droops and has no stability. If the matrix should have a pierced or broken bottom which is almost unavoidable in a deep cavity, fill it as if it were intact and unless the aperture is extremely large it is surprising how much tap- ping or forcing is required to make the porcelain pass through ; however under all circumstances it is a safe rule to turn the matrix bottom side up and examine it closely and trace it with a clean brush, other- wise a very small particle of porcelain left unnoticed and becoming fused will make the work to this point useless. If a break is made on the cavity edge of the matrix, condemn it and make another, as it is impossible to have a perfect margin unless the matrix is intact on that margin. When excess of moisture has been removed, place it on a metal or fire clay tray at the mouth of the furnace, gradually pushing it to the interior, using care that too quick evaporation does not loosen porcelain from walls of the matrix. If this occurs a refilling of the mold is the only alternative. Close the door of furnace and the process of fusing has commenced. The shrinkage of porcelain plays a prominent part in all such operations and unfortunately it keeps the most experienced "guessing," therefore those unfamiliar with 286 THE PORCELAIN INLAY. the work are handicapped at the beginning by a difficulty that mut- be reckoned with always. In fact a student's first lesson is the shows ing of an artificial tooth before fusing and after, and it never fails to create surprise and comment and is a simple object lesson that im- presses. Shrinkage of porcelain is- always a fifth of its bulk, some- times quite one-fourth. In small matrices it cannot make much change, but in proportion to the size and quantity do the diffi- culties increase. It may draw from the walls of the matrix and form crevices at those parts, or it may shrink and draw the form with it, and to avoid this my favorite way is to mix small particles of broken porcelain with the paste. Another way is to cut grooves or concaves at its greatest bulk which divides the material and avoids the crevicing to some extent. The main desire is to have a shrinkage that will change the form of the matrix the least, and some porcelains have a value in this respect. An invested matrix is more secure, but it has drawbacks that in my estimation are often detrimental. A matrix for investment must be intact at every point which is possible with gold, but not always so with platinum. Once invested it must be completed in that form thus debarring opportunities for trial or re- burnish, added to which are the increased difficulties of getting proper form or contour while invested. FUSING. This is the coherence into a solid mass of the various substances which constitute porcelain and it is this cohesiveness which causes shrinkage, and because of this shrinkage repeated firing is imperative to obtain the necessary bulk of iolidified material. It may be twice, three times or more according to the extensiveness of the operation, therefore a knowledge of fusing is an important part of making an inlay, and one that necessitates considerable experience. Of course results are obtained without experience or much practice, but these results are not always properly fused porcelain. To illustrate this point let me state that a certain dealer and manufacturer wishing to impress upon the profession the advantages of a pyrometer attachment molded small pellets of porcelain of equal size and of one color and mailed them to "porcelain workers" in various parts of the country, asking them to fuse and return. I was so favored with this request, but did not know the results for some months afterwards when by chance I saw the "returns" mounted on a card for exhibition pur- poses and the various shades and qualities produced by that one little pellet was a revelation. They were all supposed to be correctly fired FUSING. 287 and no doubt each participant in this trial thought his specimen a correct one. This shows in a simple manner why there is so much demand for information regarding shading, which demand can be lessened by greater knowledge of fusing. How can this knowledge be obtained in the most practical manner? By studying the various degrees of heat with the eye which may be aided by a watch or a pyrometer, but with either of these or any other guide the correct fusing or baking of porcelain reduces the problem to one of per- sonal equation. A pellet of gold is recommended by many to assist in determining the fusing points. The gold is placed in the muffle near the inlay and its melting denotes the fact that a certain temperature is reached, and so much time by the watch is allowed between the melting of the gold until the fusing of the porcelain. The time to allow is learned by repeated firings, but various sizes of porcelain being baked at the same time must be guessed at. The use of a pyrometer in connection with a furnace is accepted by many as being the most scientific solution of our fusing troubles, and there is no doubt that it is of much assistance to the majority, but it is a machine and therefore it has no judgment and fusing porcelain requires that necessity. Concentration of a thousand heat units for twenty minutes will produce certain results and the same condition will be obtained by increasing the volume and reducing the time, and as we are fusing irregular quantities, either the heat or fusing point must be varied because these fusing points now used as a standard were obtained by baking porcelain pellets of uniform size at a regular heat for a certain time with the rheostat on a positive point. These facts, therefore, must place the pyrometer in the position it should occupy and that it is a guide which will indicate the furnace heat and not properly tell when the fusing has taken place. The man who uses his eye as a guide can fuse any material under all circum- stances and feel that he has control of the situation, providing he uses an article which fuses at 2300° or less. Over that point it is a greater strain on the eyes and the value of a pyrometer is correspondingly increased, but the proportion of operators using such excessive heat for inlays is very small. The operator after some practice will observe that various degrees of heat have a shade indicative of the point he desires. The first will be a deep orange color which will fuse a low porcelain body ranging from 1500° F. to 1800° F. If an electric furnace is being used, ad- vancing the rheostat to the next point will increase the brightness of 288 THE PORCELAIN INLAY. the muflle to a yellow, giving a fusing temperature ranging to 2100°, and another step higher a bright yellow appearance, and a heat sufficient to fuse most of the "high fusing" bodies or those ranging in the neighborhood of 2300°. Beyond this point there is a glare that may be injurious to the eyes unless protected by smoked glasses. Dr. Hart J. Goslee, in a recent article on this subject makes a valuable suggestion that I take the liberty of quoting. "A degree of familiarity with the physical change which takes place during vitrifi- cation and which will enable one to thus detect the proper fusion, may be easily required by the continued fusing of small cubes of properly mixed 'body' placed upon the labial surface of a central incisor facing until he can distinguish between the granular surface of the ' body ' and the glazed surface of the facing and observe when the surface of the former becomes the same as that of the latter." The "first fusing" is carrying the inlay through these various stages of heat until it arrives at what is usually termed a "biscuit bake." This is a reduction of the different ingredients to a solid vitrified mass without a gloss. Drawing it from the furnace in this condition and exposing it to the air does it no injury, in fact small work even when finished does not require particular care in this respect, but large sections and crowns should be immediately placed in a cooling muffle until cool enough to handle. After the first bake the surplus platinum is trimmed and the inlay adjusted in the cavity. The removal of excess matrix material insures easier access to its position and allows a better observance of general contour. The fiat blade of a burnisher is pressed along the edges until the matrix sets firmly in position and that part of the matrix which may have been changed by the shrinkage is forced back to the cavity walls. The inlay is again removed and body added, first cleaning off the surface with a brush, being careful to have any crevice thoroughly filled with porcelain, thereby preventing little air holes which sometimes defy considerable tapping. Reburnishing the inlay will soil the surface to some extent and it may also come in contact with saliva or blood, therefore dip it in alcohol, and place at mouth of fur- nace until the impurities are destroyed by heat, thus insuring a positively clean surface and unalloyed porcelain. The inlay is again given the same considerations as at first baking, but watched with greater care when the heat is nearing the fusing point, because insufficiency of heat will not produce the true shade or finished surface, while too much heat will make it lighter in proportion to the excessive heat beyond the exact point, and reduce the quality of the material. FUSING. 289 Better results will be obtained by withdrawing the inlay before it is thoroughly fused and note the condition particularly in regard to amount of material, for if another layer of porcelain is required to give it the proper contour or to have the inlay level with the margins of the matrix, it is better to make this addition at this time, and in so doing the whole mass will be more homogeneous with a truer shade if the final heat is correctly gauged. If the inlay is satisfactory to the operator the next step is to strip the matrix, which is done with fine straight pointed tweezers, catching the outer edge and turning backwards toward the middle which will avoid chipping the edges. Very frequently small pieces of the metal adhere very persistently to sections of the porcelain. These may not be of disadvantage in large inlays, but in small ones the shade might be affected, therefore it is recommended that every portion be removed, and an old bur will do this easily. My usual procedure after stripping the matrix is to place the inlay in the cavity, always wet, which brings out the shade and adds life to it, and it is at this point the new porcelain worker has his first desire for a transparent cement. It is now that the patient is invited to view it for he is usually as interested as the dentist, and it is also good policy to explain the probable change that will take place by the drying of the tooth and the cementation. This change is often temporary though sometimes permanent, much to our disappointment, but experience may help to reduce it to the minimum. The inlay must now be prepared for retention. There are three important factors toward permanency, first, shape, which is given by due consideration of cavity preparation, second, the undercutting or serration of the porcelain, and third, the quality of cement. Many failures can be attributed to concentration on the latter, ignoring the importance of the first two requisites. Careful attention should be given to the inlay itself, large or small, thereby saving time, discomfort and reputation. My preference is undercutting or grooving when possible, but that is not always practicable, so it may be necessary to etch the cavity side of the inlay with hydrofluoric acid which has a powerful chemical affinity for all vitrified surfaces, destroying the gloss and allowing a better union with the cement. Almost the same results are obtained by using small carborundum or corundum stones, and many follow this method exclusively, while others use both roughening and grooving. The disks employed are diamond, hard rubber and corundum or carborundum. The diamond disks are expensive and unless used 19 290 THE PORCELAIN INLAY. carefully very soon lose their efficiency. The cheaper disks cut quickly and with moderate care are durable. An objection to car- borundum is its brittleness, and the fine black dust that lodges in the porcelain and is not always easy to eradicate. The groove should be made on at least two sides and more if possible. In using acid care must be taken to keep the finished surface intact and this is done by making a block of beeswax about one inch square, soften a surface over a flame and sink the inlay face down using a warm spatula to cover edges. Drop a little acid on the exposed surface and leave it for five to eight minutes, wash off with water and put the inlay in alcohol which will loosen a fine scale which is scraped off with an excavator. If this surface is not removed the cement will not get a true attachment. No matter how the inlay is prepared it should be thoroughly cleaned with alcohol. The mouth is now put in readi- ness for the final adjustment of the inlay. Thorough dryness is an important essential, and for this purpose probably the rubber dam is the most efficacious, although if one is accustomed to the proper use of napkins, the unpleasantness of the dam can be avoided in the majority of cases. The cement is mixed to a creamy consistency and applied to the cavity with a spatula and the inlay inserted immediately, forcing it to position by gentle pressure, holding it there until crystallization has commenced. If the inlay is of a simple character further direc- tions are unnecessary, but if complex and extending to the incisal or occlusal surface material assistance is obtained by a soft wooden wedge such as a tooth pick, or waxed floss silk wound about the tooth. A tape floss silk or cotton strip is advantageous because the broader sur- face equalizes the pressure and as it is drawn over the joints it removes excess cement and exposes the union, showing at a glance if the porce- lain has its correct position. When it is not convenient to do this use small squares of spunk, which is soft and firm, for the removal of excess cement while it is soft has a distinct advantage. After the cement has set and before removal of dam or napkin cover the operation with some moisture preventative such as sandarac or rubber varnish, chlora-percha or paraffin wax. The last men- tioned is preferable because it is not disfiguring and gives a blending effect to the porcelain and tooth and will remain a sufficient time for the purpose desired. The inlay may be finished in an hour or at some future sitting for there is always some finishing with the most perfect work. It may be only a slight disking or it may be that edges need a stone. If so use a small narrow edge of fine grit, grinding no more off the glossed surface than positively necessary, although at PORCELAIN SECTION ATTACHMENT. 29I times the occlusion is such that the surface must be defaced. After grinding, the surface should be polished, smoothness being the main object. PORCELAIN SECTION ATTACHMENT. When it is possible to use an all-porcelain anchorage in restoring a section of a tooth, that method is preferable, because the whole mass of material is of one substance, thereby rendering greater resis- tance to leverage; but occasionally we must resort to other means of retention, and the use of platinum wire pins, loops, or staples is rec- ommended. Pins from old porcelain teeth can be used without any other prepara- tion, but they are too thick and rarely indicated in preference to the loop or staple, the latter being adapted to almost every purpose and being also easier to manipulate. Directions for their use are few and easily followed. The tooth is prepared as directed on previous pages, and a platinum matrix made of the edges and cavity, the thick- ness the same as in other inlay work excepting for the cross-section Fig. 258. Fig. 259. Fig. 260. of a tooth, when. it can be slightly heavier. The wire being the an- chorage, it is unnecessary to cover the floor of the cavity with platinum, therefore breaking the matrix is expected. This being done, take iridio-platinum wire gauge 24 and bend in staple form to fit. Figs. 258 and 259 give the idea of wire formation for a majority of cases, while that shown in Fig. 260 is probably more desirable where there is extreme sensitiveness, it being easier to place retention holes for wire ends than to cut across the tooth to accommodate the loop. The staple with points in the porcelain is stronger, however, than that with the points in the tooth. The attachment to the tooth may be equal in strength, but the tip or corner or any section of the porcelain having the least foreign material must be the stronger, hence the argument in favor of an all-porcelain attachment when that is possible. The weak points of the porcelain shown in Fig. 261 are opposite to the ends of the wire, while the weak point of that shown in Fig. 262 is as far as the loop extends, although this weakness will be less in pro- portion to thickness of the porcelain. While the matrix is in position, the wire is inserted and held there 292 THE PORCELAIN INLAY. with paste porcelain made of water and gum tragacanth or mixing fluid. Absorb moisture with bibulous paper or spunk and then gently withdraw the combination from the tooth, and after carefully drying at the mouth of the furnace fuse it the same as other work. These few simple directions will save the time and trouble nec- essary for soldering the staple and matrix together, and will also insure a purity of porcelain not otherwise possible. Fig. 263 shows the loops or pins attached in the porcelain and ready E3^ Fig 261 Fig. 262 Fig. 263. for trial, reburnishing the edges and finishing as represented by Figs. 264 to 267. Fig. 268 is a part section of a bicuspid showing a way of restoring that is most satisfactory. I have made many such cases, and have yet to learn of the first failure. A whole crown is no doubt quite as easy to make, but at times a demand for the least loss of tooth makes such a repair desirable. The building of tips and corners can be more quickly accom- plished by using pieces of broken porcelain tooth in the foundation, thus allowing a high heat without change in the prominent contour. Some years ago a firm in London introduced small wedges of porcelain called "Mellersh Cores," their name being taken from Fig. 266. Fig. 267. Fig. 268 that of the inventor. They are in various shades and will take a high heat without change of form or color, and can therefore be used to advantage in contour work. CEMENT. It is generally conceded by porcelain operators that while a material of this kind is almost an ideal filling, it falls short of the ideal because we are forced to use as an attachment a substance detrimental to the aim which we have in view, namely, the absolutely invisible restoration of tooth form. Though approximating the ideal we can never fully CEMENT. 293 reach it while we have to depend upon an opaque substance as a means of retention. Still the many good qualities of cement will insure its use for many years to come, for even if an ideal cement should be dis- covered it will take time to establish a confidence equal to what we now have in the material at present in use. The question may arise as to what is an ideal cement. In many cases what we are now using is ideal, that is from a tooth saving viewpoint, but its failure is that it does not save itself. Cement saves the tooth and porcelain protects the cement, thus making a combination which but for esthetic reasons would be almost perfect. Translucency and perfect color matter little in some instances, but in others they are highly important and the profession should hail the advent of a material having all the necessary qualities as the fruition of a long desire. Porcelain inlays can be made perfect in shade and shape and the texture may approximate tooth substance in a highly satisfactory manner, but immediately upon attaching it permanently the shade is changed through the difference between the three substances, all of different density, coming in close contact, namely, porcelain, cement, and tooth. The cement being the chief point of difficulty, it is im- portant that the objectionable features should be reduced to the minimum. It is a poor cement that is not at least a preventative. Many resemble each other in manipulative qualities with the difference of slow, medium and quick setting tendencies. Some are coarse and others are fine and a few have a combination of many good qualities, but with that tendency to "pack" under pressure which causes annoy- ance to porcelain workers. A cement closely ground of clear color and medium to slow setting, having the maximum adhesiveness with the least amount of powder is what is recommended for a successful operation. In addition to this, it should have the greatest amount of resistance to moisture during what is usually called the "setting" period. Shading a cement to match the tooth, or to lighten or darken either the porcelain or tooth or both is quite troublesome, and, at times, disappoint- ing. It is of considerable assistance to mix pellets of cement of various shades and mount them on a card. This allows of comparison and saves much time and guesswork. Yellows are the most required, and this is fortunate because pure calcined oxide of zinc is yellow, ranging in degree of shade from a canary color to cream white, and its chemical combination with phosphoric acid is more complete than when other- wise changed. The variations in shade depend upon the product 294 THE PORCELAIN INLAY. and it is conceded that the best quality of zinc oxide comes from France. This is of the lightest shade, but it is not safe to assume that the light shades are all of this origin, because manufacturers sometimes produce these variations by coloring matter which has a deteriorating tendency. It may be infinitesimal in blues and grays, but white is made so by oxides of aluminum or zinc which reduce the chemical union of the powder and acid in a marked degree. All phosphate of zinc cements are similar in manufacture and much the same results are obtained, although some are better adapted than others to use in connection with inlays. Some inlay troubles are caused by injudicious selection of cements, that is using a quick setting cement instead of a slow one, or vice versa. Another factor is improper mixing in the way of insufficient spatulating which gives poor results through non- incorporation of the two ingredients. Cement mixed too thin will not have the body of material required for resistance, with the added danger of displace- ment during the longer period which it takes for setting. Cement mixed too thick prevents proper seating of the porcelain and a close union, with probability of fractured edges through endeavors to force it to place. Quick setting cements should be avoided in complicated conditions. Slow setting cement has less value on corners and tips, for usually such places have free access and a quicker setting cement will reduce the possibility of displacement, which is increased through prominence. In the past four years much attention has been given to the new silicate cements which are on the market under various names with many impossible recommendations, therefore a word on this point may be of some interest particularly in connection with porcelain inlays. These cements are nearly all produced in Germany and it has been my fortune to be familiar with this material almost from its origin, and in that time have formed conclusions through actual observations that may be useful. These silicate cements have not that perfection claimed by the manufacturers and agents, but they have reached a stage wherein it is safe to prophesy an ultimate success, how soon, it is not possible to say. That they meet all requirements at present or that they can take the place of porcelain is not worth argument, but as an attachment they come nearer to the ideal in appearance than anything yet produced. Their strength and adhesiveness to tooth structure cannot be compared with the ordinary phosphate of zinc cement. In mixing a silicate cement one is impressed with its tenacity to SHADING. 295 smooth surfaces, leading to the belief that it must be particularly appli- cable to porcelain restorations, but in many practical tests it is found that after a few months this adhesiveness has decreased and the filling is easily dislodged. This being the case its use as a medium for inlay attachment is somewhat hazardous. It has a value because of shade and its resistance to "washing out," but this is counterbalanced by crevicing and fracturing and changing appearance in many mouths. And yet there are instances where this material wears well and after three years has almost the appearance of porcelain, but these cases are rare. The writer has been using a new cement for a year called " Tenacit" made exclusively for attachment purposes, which is apparently the long desired medium for cementing the porcelain inlay to tooth substance. It is adhesive, translucent and a resistant to the oral fluids, pro- ducing a restoration so much desired and hitherto impossible because of the opacity of the dividing line. This material is now made in Germany and will soon be on the American market and it will no doubt increase the value of porcelain restorations. SHADING. The color problem in connection with inlay work is one of much inquiry and discussion. It is a phase of the work most perplexing and the rules given by some authorities are both diversified and difficult, requiring close attention even by the most experienced and often proving discouraging to the beginner. The size and position of an inlay will govern shade to such an extent that consideration of this fact is one of the first rules. The application of the shade guide to the tooth may lead to an incorrect conclusion, because quantity of material adds depth to the shade and most of the guides are pointed. Frequently the point is placed against the tooth without allowing the eye to take in the whole size and general effect. Thus when the inlay is finished it is found to have a lighter appearance which is an error not readily rectified. Overfusing is probably the cause of more poorly shaded inlays than wrong choosing of shade, therefore the choice of something slightly darker is recommended particularly if the operator has limited experience. A rule which can be applied more frequently to a simple labial inlay is to choose a shade darker and reverse the order when applied to small proximal cases. Some- thing darker between the teeth will surely cause a shadow which can be avoided by lighter shades. The cement which is the background is an opaque substance and is therefore a strong factor and one that 296 THE PORCELAIN INLAV. must not be overlooked, but even with this consideration in mind the most beautifully shaded work is sometimes disappointing. In many cases, however, this is corrected to some extent by time. In larger inlays and sections of porcelain the cement interference is reduced by being overcome with volume of material and stronger basal shade body which is toned to the desired shade by lighter tints. Various degrees of yellow are used as foundation shades in the majority of cases with the possible exception of pulpless teeth. These teeth having decreased translucency the opacity of a solid mass is not so noticeable and the question devolves to one of matching alone. And yet the shading of such a tooth requires considerable artistic skill because the operator must do the blending to suit the various shade conditions present and which are not to be found on any one shade guide. Take, for instance, a large incisal contour embracing one-fourth of the tooth with pulp alive, and the shades may vary from a deep yellow near the gum to a light yellowish-blue at the incisal. This would be matched up with three shades, which are all listed and ready for the mixing; but if pulpless the neck portion might be a brown with a greenish-blue center and a lighter hue at the edge, thus showing that considerable mixing must be done which means guesswork in many cases. The artistic porcelain manipulator is handicapped when compared with a painter who has his palette and colors and desires certain difficult combinations to portray what he sees or is in his mind's eye. He mixes and sees immediate results, whereas with porcelain the shades are powders with no color guidance until the mass is reduced to a vitreous substance, and then not correctly so unless the artistic sense is carried to a completion. A great quantity of matter has been written and published in regard to the proper way to shade porcelain and many excellent rules are formulated, which if they could be carried to a successful issue at all times would reduce this problem to perfection, but rules and directions are of little value without artistic skill to carry them out. This cannot be bought although it may be acquired to some extent, and yet it must be inate in the same ratio that mechanics are part and parcel of the successful dentist. Rules may assist but they cannot always be practical. It is claimed that the most successful mode of shading is to build the inlay by layers of different enamel shades which "break up the absorption and refraction of light rays," thereby giving an opalescence to the inlay not to be obtained otherwise. This is excellent practice and cannot be criticised when circumstances favor this procedure, but there PORCELAIN BODIES. 297 are times when the blending of shades will give equal if not better results and the simplicity of blending is much easier grasped by the inexperienced. Outside of this is the fact that with one exception all inlay materials are made for blending and the thousands of beauti- fully matched inlays made with these materials must prove the fact that merit is not limited to the layer method alone. Dr. W. T. Reeves originated this method and to him we owe much valuable literature on this subject, therefore it will be of interest to reprint what is claimed by him can be accomplished by observing these three rules. *' First. A neutral translucent-looking inlay. Put colors on strong enough, that when covered with what might be called an enamel layer will allow the colors to reflect through, the enamel layer modify- ing and harmonizing the colors. This will give the translucent effect so desirable. " Second. If built of three or more layers of different bodies it will break up the absorption and refraction of light rays, so that from whatever angle or point of view looked at it, it will appear practically the same. An inlay built all of one body or mixture will absorb light only from one direction, and viewed from one point will look all right, but from the opposite point of view will show as differently as black and white. An inlay in layers will come very near imitating nature's method of building up a tooth and by breaking up the direct absorp- tion and refraction of light rays, will come very nearly looking the same from all points of view. " Third. You overcome that great bugbear of most inlay workers, the cement showing through after the inlay is set. An inlay built up in layers will almost overcome the reflection of the cement through from underneath. You will often hear operators say they had a splendid color before the inlay was set, but after it was set the cement killed it entirely. That was because the inlay was baked all of one body and the cement could reflect through from underneath as easily as the light was absorbed only in one direction from above. The three points I claim for this method are translucency, avoidance of shadow, and prevention of cement reflection from underneath." PORCELAIN BODIES. Until recent years the advancement of porcelain operations was much retarded because of few and unsuitable materials, but now the variety is almost bewildering. In fact it is a question if the market is not overdone in this respect. 298 THE PORCELAIN INLAY. There can be no objection to every porcelain operator having a varied stock of porcelain, provided his experience has been sufficient to enable a skillful discernment of the various qualities of each, and thereby produce gratifying results by eliminating those of lesser merit until he has secured what in his hands will give the best basis for general application, but the beginner is likely to be confused by so many different makes. The value of a product in the eyes of many is the assortment of shades. This of course is natural if the operator has had little ex- perience, but as he becomes more skillful he finds that at least half the number is sufficient because he has learned that a little manipula- tion of a certain few will give the same results in the majority of cases. This statement will be better appreciated by those who have had to contend with the earlier condition of affairs, when only a few stronger shades were available, and they will also agree that an ideal shade guide could be limited to a dozen and then readily cover all require- ments. The porcelain inlay worker of eighteen or twenty years ago, had much to contend with and many discouragements to overcome, and much of the antipathy to this new branch of dentistry was no doubt caused by the crude appearance of many so-called finished operations, some of which were far from esthetic whilst those having that recommendation were cases fortunate enough to be within the range of two or three varieties of continuous gum bodies such as Allen's, Tee's and Close's. These gave a few shades of yellows which were regulated to a great extent by heat, therefore a tooth with gray or blue tints to be matched up with yellow meant a discrepancy of shade which justified much criticism. Subsequent events have proven that these efforts had merits because they resulted in different manufacturers putting various porcelain bodies on the market, with a larger number of shades and varying degrees of fusing point. Porcelain work was increasing rapidly in the latter part of the nineties and in 1898 received a gratifying impetus by the introduction of Dr. Jenkins' low fusing enamels with an outfit particularly designed for using this material with a gold matrix, for up to this time platinum was used exclusively for that purpose. The advent of these goods and the process of using them was the origin of the controversy still existing in regard to the superior virtues of low fusing porcelain over the older and longer tried high fusing. This question has been debated in public scores of times and it is still unsettled, although the differ- ences of opinions are not so positive, for adherents of both factions are forced to admit that each have certain advantages, which when FURNACES. 299 properly recognized lead to the ultimate gain of the work. The introduction of Brewsters' material was an advanced step for the cause of high fusing porcelain and he was the first and only one to give us enamels with basal shades, thereby increasing the possibilities of translucency which was lacking in many products. The writer under- stands that Brewster's goods are no longer on the market. During the past five years the S. S. White Dental Co. have done much toward the advancement of porcelain, having introduced a variety of shades at various fusing points. The Consolidated Dental Co. have also a splendid assortment with a fusing point sufficient to satisfy the most enthusiastic advocate of high temperature. Johnson and Lund's goods are of the best quality and the fusing point is also high. It is generally conceded that a fusing point of 2200° or 2300° is sufficiently high and quite suited to inlay purposes and the increased strain on the electric muffle and the extra time required for such heat counterbalanced the small advantage of an extreme heat if such exists. The following goods having been thoroughly tested can be considered of a standard quality and the assortment is varied enough to suit any demand. Whiteley's 19 shades fusing about 2300° S. S. White Dental Co., 26 shades fusing about 2300° Jenkins Dental Co., 18 shades (gold matrix) 155°° Consolidated Dental Co., 23 shade 2600° Johnson and Lund, 25 shades 2550° Ash and Son, 7 shades 1900** FURNACES. Porcelain as applied to dentistry at the present time has assumed such importance that it is difficult to conceive of the fact that only twenty years has elapsed since the invention of the first furnace which reduced the time of fusing small pieces of porcelain to a matter of a few. minutes, and to this fact we owe the real birth of that branch of dentistry which is generally conceded to be a distinct advancement. There is no doubt that tooth carvers and continuous gum workers of many years back have had visions of what the present generation enjoys by the adaptation of this esthetic work, and they have given much thought toward the solution of the fusing problem, for that was the obstacle first to be overcome, having recognized the futility of much advancement while harnessed to the cumbersome and slow coke furnace. The quality of workmanship produced in this manner is beyond our criticism which proves that improvements in that direction were not required, but toward reduction of time and convenience so that small work could be possible and with little preparation. 300 THE PORCELAIN INLAY. To Dr. C. H. Land, of Detroit, belongs the honor of being the inventor of the first small furnace distinctly different from any other and especially adapted for this work, in which he takes such an im- portant position in its history. Much praise must be accorded him for his persistent efforts and inventive genius. This furnace was called a "Compound Gas or Gasoline Furnace" Fig. 269. and was first described to the dental public in Items 0} Interest, Oct., 1886, under the heading "Are Hydro-carbon or Gas Furnaces a Success?" (Fig. 269.) These furnaces were lined with fire clay with a muffle of the same material. The air blast was supplied by a foot bellows and took about thirty minutes' continuous pumping to secure the necessary heat. The results were not always satisfactory, as frequently the gas FURNACES. 301 was forced through the muffle causing "gassing" which was a diffi- culty to be contended with in using any gas furnace. Four years later the same inventor produced a smaller furnace of the same kind which was called "The Midget Blast Furnace" and was a decided advance because the muffle was much smaller and made of platinum, thus aflowing quicker heating and reducing the "gassing," tendency (see Fig. 270). These little furnaces could be heated sufficiently to fuse the highest grade material in seven to ten minutes and have been a decided favorite over all others of the same kind, and there are many still in use at the present time. In fact, the writer did not discard his until eight years ago, because its efficiency was in marked contrast to the troubles of the more modern electric. These troubles have been reduced to some extent, but entire elimination must not be expected. In the early nineties several gas furnaces were marketed, the most notable ones being Parker- Stoddart, Fletcher, and Downie. The application of electricity to dental appliances became gen- eral in the early nineties and when Dr. L. E. Custer invented the first practical electric furnace in 1894 the improvement was considered to be a marked advancement, be- cause heretofore the fusing of por- celain by means of gas meant labor Fig. 270. to produce the blast which with its attendant noise was most undesir- able. Electricity eliminated the possibility of "gassing" the porcelain, a trouble which cannot be understood unless experienced and one which added much to the discouragement of the early porcelain workers. This new furnace being absolutely noiseless and clean was an addition to the operating room and thereby a convenience much appreciated. Its form was adapted more to the use of continuous gum work and is shown in Fig. 271. It is practically unchanged at the present time, the only improve- 302 THE PORCELAIN INLAY. ment being in the heat regulation and easier repair necessitated by wires "burning out." In fact the trend of improvement in all dental furnaces from this date forward has been mainly toward the reduction of this trouble. Two years after this first electric furnace, or in 1896, the Detroit Dental Mfg. Co. marketed the "Downie" which differed from the former mainly in general form of the furnace and the mode of wiring the muffle. Fig. 271. The next furnace brought to our attention was a very small one invented by Dr. Mitchell, of London, and intended for low fusing bodies as it was practically useless for anything higher than Ash and Son low fusing porcelain. In 1899 and 1900 there were three more, viz., Hammond, Peck and Gerhardt, then the Pelton in 1902 and Price's in 1903. The most recent addition to a numerous list is Roach's Auto- matic and Caulkins' "Revelation" in 1905. The Hammond had a valuable distinction from all others from the fact that in case of wires burning a new muffle could be substituted immediately. This im- FURNACES. 303 provement was a decided advantage and other manufacturers soon made the same arrangement. The Hammond is now substituted by a newer design made by the S. S. White Dental Mfg. Co. The Price was introduced to the profession with a pyrometer attached, and this im- provement has resulted in all the leading furnace manufacturers at the present time having a pyrometer attachment in some form or other. There is very little difference in the merit of these various furnaces, therefore the intending purchaser cannot be far astray in a choice of any one mentioned, although it is important to consider the amount of heat developed on the first step of the rheostat if the dentist is using low fus- ing material, as several furnaces develop a heat at that point great enough to destroy that material unless watched very intently. For many years porcelain oper- ations were confined to those for- tunate in having electricity or gas conveniences, relegating the practi- tioner without these advantages to the rear of the vanguard of dental progress. This may not have been a hardship to the majority, because in small places the demand for por- celain work is always limited, but there are many dentists ambitious to do all kinds of work, therefore the introduction of the gasoline dental furnace by the Turner Brass Works, of Chicago, in 1900, was a decided step toward the advance- ment and equalization of the pro- fession at large. The furnace is simple of construction and capable of producing a heat sufficient to fuse any porcelain and will do it quickly and safely. This apparatus with the accompanying soldering appliances enables the rural dentist to be an up-to-date practitioner and the numerous sales of this furnace is a testimony that this fact is appre- ciated. There is also another gasoline furnace called the Brophy, which is similar in construction and has equal merit with the original. In conclusion it is apropos to state the fact that improvements in appli- ances for the purpose of fusing small quantities of porcelain quicker Fig. 272. — Lewellan furnace. 304 THE PORCELAIN INLAY. was applied on a larger scale to the manufacturing of teeth with the result that the old fashioned coke ovens are now obsolete, having been replaced with the more modern oil burners, which are quicker, cleaner and save much labor. They are an improvement and an enlargement of one made for continuous gum by Dr. C. H. Land, in 1892. The simplicity of its form and amount of high heat produced was one of wonderment to the profession at that time. The fuel is the regular refined petroleum or "coal oil" syphoned to a burner at the base of the furnace, which is so constructed that a natural draught is all sufficient to produce the highest heat required to fuse any porcelain body. They are absolutely without noise or odor and very economical and highly satisfactory in smaller sizes for continuous gum work, but they can only be used where there is a chimney which is necessary for the draught. (Fig. 272.) To Mr, Lewellan, of Philadelphia, must be credited the improve- ments of this furnace which has revolutionized the mode of fusing large quantities of porcelain. CHAPTER XVII. CONSTRUCTION OF GOLD INLAYS. JOHN EGBERT NYMAN, D. D. S. Recently the construction of gold inlays has been entirely revolution- ized. A method has been devised by Dr. W. H. Taggart, of Chicago, which supplants all other methods. Applicable alike to simple and to complicated cavities in any situation, obtaining readily any desired proximal contour and occlusion, and with uniform certainty of absolutely accurate results, it may well be styled "the best" method of gold inlay processes. It embodies all the factors that are requisite of any method that maybe termed "ideal," such as accuracy and permanency of results, comfort of patient and operator, ease of manipulation, economy of time. It is essentially a method of accurate casting of gold inlays, some- thing heretofore impossible, but now easily accomplished by means of a marvelously ingenious device for the application of gas pressure to molten gold. One of the essential problems in this process of casting inlays, which had to be solved was the obtaining of a mold which should have no joints or crevices about it; this necessitated a model of the inlay desired, that could be dissipated completely without residue, by some means which would not in any way injure the mold. Dr. Taggart finally succeeded in producing a wax of which a model inlay could be made in the cavity of the tooth, carving it to the desired contour, proximal and occlusal. It was essential that the wax become plastic at a temperature that could be tolerated by the tooth, that it would not shrink or warp in cooling, that when cool it would be so hard that it could be removed without distortion, but would not be so brittle as to crumble under the carving instrument, that it could be vaporized by heat. All these essentials were finally obtained. Then there was the problem of the mold. Of what should it be composed and how constructed? It was essential that the mold material withstand a temperature of at least 2100° F. or 1170° C (slightly above the melting point of pure gold) without shrinking, cracking or softening; that it should be finer in texture than any invest- NOTE. — Figs. 274, 275, 276, 278, 279 and 280 have been supplied through the courtesy of "Items of Interest" and are copyrighted by Dr. H. J. Goslee. 20 305 306 CONSTRUCTION OF GOLD INLAYS. ment material with which we were then familiar; that it must present an absolutely smooth surface in the mold cavity; that it should set sufficiently hard to permit of manipulation without crumbling. This was finally obtained by a combination of silex magnesia and plaster. These two factors having been obtained, there still remained to be devised some method of forcing the molten gold into the mold so that it would fill the mold to the uttermost corner, a rather difficult problem considering the strong tendency of gold to "spheroid", as it is tech- nically termed, or "ball up" when in a molten or fluid condition. The genius of Dr. Taggart, which had solved two of the problems, proved fully equal to the third, and at last after months and months of experimenting with nothing to aid him but his own inventive ability, his masterly knowledge of physics and mechanics, and his faith that he would at last succeed, he did succeed in constructing a machine that would accomplish all that was to be accomplished and so complete was his success, that it was absolutely startling to the profession, creating a sensation such as had never before been known. It is no exaggeration to state that in the history of the profession nothing to equal this process in value has ever been given it. The method is as follows : The cavity having been prepared, a mass of the special wax (which is dark green in color in order that the slightest overlap on the surface of the tooth may be readily noticed) sufficiently large to more than fill the cavity is softened by immersion for about five minutes in water of a temperature of from 13 5°- 140° F. or 77° C. This softening must be done carefully and the wax must not be manipulated until it is softened through and through. If insufficient heat is used the wax will crack when it is forced into the cavity. If too much heat is used the surface of it will become pasty and will crumble when an attempt is made to carve it. To soften it in or over a flame must never be attempted as the surface will flow and then become pasty while the interior mass remains too hard to be manipulated. Until one becomes familiar with this softening process, it will be best to use a thermometer to determine when the proper heat (140° F.) has been obtained. A very simple and efficient method of softening the wax is as follows: Obtain a thin cork of large diameter which will fit into an ordinary drinking glass and yet project slightly above the edge of it. Thrust three or four large pins through this at a distance of about half an inch from the center. Pieces of wax are forced slightly onto the points of the pins — the glass is filled with water of about 140° F. — the cork is pressed lightly into the glass and the pieces of wax will then be so immersed in the water that the temperature is uniform CONSTRUCTION OF GOLD INLAYS. 307 on all sides and in a few minutes the wax will be softened evenly through- out. While the wax is softening, let the patient hold water as hot as can be tolerated in the mouth in the vicinity of the cavity so that the tooth will not chill the wax too quickly when it is inserted in the cavity. The mass of wax first softened should be shaped up by the fingers so that it will approximately fit the cavity, then the partially shaped mass is softened again and pressed into the cavity; this will insure its being forced into every corner of the cavity without cracking. The wax is inserted into the cavity (which must be moist), pressing it in with the finger tips rather than with an instrument. The patient is at once instructed to bite into it and to chew upon it. It is then hardened by chilling it with a stream of cold water or having the patient fill his mouth with cold water for a few minutes, Fig. 273. — Instruments for trimming and carving wax fillings for gold inlays. I. For occlusal surfaces. 2, 3, 4. 5, 6. For proximal surfaces and trimming along buccal and lingual margins. 7, 8. For proximal surfaces, cutting through at contact point and trimming along gingival margins. then with suitable instruments first carve the occlusal surface to proper contour, carving flush to the marginal edges, leaving no overlap on the surface, the mass which is wedged into the proximal surface holding the filling in place during this oper- ation. The occlusal surface having been carved, with suitable in- struments proceed to carve the proximal surface, holding the wax in place by light pressure with an instrument on the occlusal surface. Do not attempt to carve thick slices off the wax, but simply shave it off with a movement parallel to the margin until at last it is carved flush to the margin with no overlap remaining. The buccal and lingual sections should be carved before proceeding to carve the gingival section, i finally passing a very thin instrument through the contact point and slicing off the portion which may have squeezed under the contour of the adjacent tooth. (Instruments suitable for this carving are shown in the accompanying illustration.) Fig. 273. 3o8 CONSTRUCTION OF GOLD INLAYS. This method is known as the direct method. Many competent op- erators obtain splendid results by what is known as the indirect method which consists of taking an impression with modelling compound such as that manufactured by the Detroit Dental Mfg. Co. or the Loch- head Impression Material, manufactured by Lochhead of New York. A matrix of thin copper or German silver or a cavity impression cup must be used in obtaining the impression. The impression cups de- vised by Dr. F. E. Roach trimmed and shaped according to the cavity in the case are very useful. This taking of the impression can be done in a remarkably accurate manner provided the operator will train him- self in the technique of it, and an accurate impression is absolutely essential to the success of this method. After the impression has been secured, a bite is taken in wax or the softer modelling compounds. The impression is imbedded in plaster, a model is made, with a pyramidal base, of "technique cement" or amalgam (the writer preferring the former). This model when removed from the cavity impression is trimmed if necessary until it can be placed in the proper position in the bite, the pyramidal base is oiled, and articulated models are run in plaster. The wax model is made in the model cavity and the occlusal surface trimmed to proper shape. Then the cement model is removed from the articulated plaster model and the wax model carved to proper prox- imal contour. The gold inlay is then constructed after the manner of the direct method. After the inlay has been cast it is replaced in the cement or amalgam model and polished. This method obviates the difficult carving about the gingival margins of a wax model in the mouth in certain classes of cavities, which carving is often an exacting and anxious process, involving considerable discom- fort to the patient. It also obviates much of the finishing and polishing that must be done in the natural tooth if the direct method be used. Furthermore, should a casting happen to be faulty another inlay may be constructed without necessitating another appointment for the patient to secure a second wax model. This method also saves the operator as well as patient considerable time at the chair and if the operator has a laboratory assistant it relieves him of many details. This method cannot be employed as successfully as the direct method in cavities involving both mesial and distal proximal surfaces as well as the occlusal surface in teeth of marked contour. The writer employs the indirect method in many cases and, technical and theoretical criticism to the contrary notwithstanding, has seen re- sults in the practices of Drs. Tracy, Gillett and Rhein of New York and CONSTRUCTION OF GOLD INLAYS. 309 Dr. Knowles of Chicago by the indirect method which could not be adversely criticized. Should the cavity extend rootwise considerably under the gum mar- gin it may be necessary to adjust a matrix to secure an accurate mar- gin at the gingival section, this should also be done in complex cavities including a large buccal or lingual section of the tooth as well as the proximal. In such cases it is well to note the character of the bite before adjusting the matrix, then carve the occlusal surface from memory, so to speak, afterwards remove the matrix, carve the buccal and lingual proximal sections, then while thoroughly chilled have the patient close the teeth very carefully, if the occlusion be too high, note the point and carve it away. In cavities which include mesial, distal and occlusal surfaces it will be advisable to fit a band matrix which will encircle the tooth. This may be constructed of thin platinum or silver, and such a matrix when properly adjusted will not interfere in the least with the bite. The writer has encountered some cavities, however, to which a band matrix could not be adjusted and without which an accurate wax filling for the cavity could not be constructed. One of this character which he was called upon to fill recently was a lower left second molar, the cavity extending from the mesio-buccal angle around to the disto- lingual angle and the gingival margin of which lay about 2 mm. below the gum. The pericemental attachment was practically at the cavity margin and this would have precluded the adjustment of a band matrix even if the other difficulties to its adjustment could have been surmounted. The case was operated on as follows : An impression of the cavity was taken with base-plate gutta-percha, it being possible with this material in a semi-plastic condition to force it slightly over the cavity margin lying beneath the gum. From this im- pression a cement model was constructed, mounted in the die cup of one of the swaging machines and a i/iooo platinum matrix was swaged and carefully trimmed to the gingival margin, then a hole about 3 mm. in diameter was cut in the center of the matrix and it was re-swaged. This matrix was then adjusted in the cavity and trimmed just flush with the gingival margins, without overlap at any point, then a mass of inlay wax was softened and pressed into the matrix while in the cavity and the patient was allowed to bite on it. This was removed from the matrix and the matrix from the cavity, both matrix and wax were carefully dried, the wax was then placed in position in the matrix and the crevice that was found along the gingival margin 3IO CONSTRUCTION OF GOLD INLAYS. between the wax and the matrix was filled by carefully flowing melted wax into it by means of a small spatula; the wax filling now being adherent to the matrix it was replaced in the cavity, it was noted where additional contour was needed and wax was flowed on at that point, when the proper contour was at last obtained. Matrix and wax filling were removed thoroughly chilled, then with a large spoon ex- cavator, a concavity was cut in the wax through the hole in the center of the matrix; this was to provide for additional mechanical retention of the inlay and may be resorted to in any inlay where the retentive shape of the cavity seems to be inadequate, and the securing of ad- ditional retention would jeopardize the stability of the remainder of the crown of the tooth. Recently Dr. F, E. Roach of Chicago has devised an instrument for hollowing out the wax models without danger of distorting them. It is a very useful instrument and can be procured from any dealer. Before attempting to hollow out the model or to trim off any over- lap which may be found at a point that was not quite accessible to the carving instruments the operator is advised to mount the model on the sprue-former as described below, then the model may be held in a manner that cannot damage the fine marginal edges. The function of the platinum matrix in the case just referred to, was simply to give a definite edge to which the wax filling could be trimmed to secure an accurate adaptation to this obscure margin so that there would be neither protrusion or recession at the cavity margin, either of which would probably have caused chronic gingivitis. Subsequently, the gold was cast into this platinum matrix which became part of the permanent inlay. If, upon removal of the wax model from the cavity, it is noted tfiat the margin is faulty or indefinite at any point, this fault may be cor- rected by chilHng the model thoroughly, drying it, pressing a small strip of parafi&n upon the faulty margin, replacing the model in the cavity and slowly pressing it to place; the heat of the mouth while not affecting to any appreciable degree the hard wax model will thoroughly soften the paraffin so that simply the gap in the margin will be filled by it; then chill thoroughly; upon removal a definite margin will be found where it was faulty before. In case of pulpless teeth additional retention may be secured by inserting an iridio-platinum post (about i8-gauge) in the root canal. This should be inserted after the wax filling has been carved. Heat the post (see that it is dry and slightly roughened) and pass it through the wax filling into the root canal; it should be hot enough CONSTRUCTION OF GOLD INLAYS. 311 to melt the wax as it comes in contact with it so that it will pass through the filling without force enough to crowd it from the cavity. When chilled the wax will be adherent to the post and can be removed from the cavity by simply grasping the projecting^end of the post and re- moving it and the filling together. If matrices or posts are used they should always be of platinum and iridio-platinum respectively, as gold matrices and posts oxidize Fig. 275. slightly when the mold is heated up and the cast gold does not adhere perfectly to them. The wax filling having been completed and removed, it is washed in cold solution of soap and water by means of a camel's hair or sable brush to remove any film of saliva that may be Fig. 276. adhering wnich would cause a faulty mold, thoroughly chilled in ice water, then a little brass rod about 10 mm. long and 2 mm. in diameter, technically known as a sprue-former, is heated by dry heat, and pressed into the wax at either the occlusal or the proximal surface (Fig. 274), preferably the latter. Recently Dr. H. N. Orr of Chicago has devised a very useful and ingenious little instrument for attaching the sprue-former to the wax model while it is in place in the cavity of the tooth (see Fig. 277). 312 CONSTRUCTION OF GOLD INLAYS. It consists of a split tube A which holds asprue former with a slight spring clutch. This is soldered to a nozzle C which has its opening at side B instead of at end, this opening extends through the split tube, at the butt end of the nozzle is attached a rubber bulb D similar to the bulb of the ordinary medicine dropper and which projects through an opening in the side of the hollow handle E. These parts slip together and are held by friction clutch alone. The bulb D is first filled with ice-water — then a sprue former is slipped into the split tube, the wax model in the tooth cavity is chilled and lifted from the cavity with an explorer; that one may be assured that it will draw easily, then replaced in the cavity, and chilled again. The sprue former is heated slightly at the tip so that it will imbed itself in the wax model without pressing it out of shape, the instant it is imbedded slight pressure with the thumb on the bulb through the side Fig. 277. of the sprue holder (which should be held as one would hold a pencil), throws sufiicient ice water on the sprue former to chill it and harden the wax where it was softened in imbedding it, and the wax model may be lifted from the cavity. It will require a Uttle practice to accomplish this as it should be done, but once this little skill has been obtained it affords a splendid method both of removing the wax model and attaching the sprue former without danger of marring delicate margins or bending extended arms of the wax model. Fig. 278 After removal of the wax model by this method the sprue-former is easily removed from the holder by grasping it with a pair of pliers just below the split tube and pulling it out. These instruments have not as yet been placed on the market but one can have one made by almost any instrument-maker. This brass rod is now inserted into the hole in the center of the base plate of the molding flask which consists of a metal ring, and a base plate (Fig. 275). Then the investment or mold material is mixed to about the consistency of thick cream. In mixing this simply sift the compound into the water, CONSTRUCTION OF GOLD INLAYS. 31: Fig. 279. avoid stirring it so that there will be no bubbles, complete the mixing by revolving the rubber cup (Fig. 276). Dr. Taggart has devised two measuring cups, one for the water and the other for the compound which gives just the proper proportions (Fig. 278). The compound sets slowly so that there is ample time for careful, deliberate application of it to the wax model. It should be applied with either a small sable brush or small pointed spatula; a little is laid on at a time and carefully worked into all the corners and angles, especially along the lines of the margins, then after all the surfaces have carefully been covered, more compound is added until the model is covered at all points with an investment about 2 mm. thick. The wax model should never be chilled just before this first application of the investment, instead it should be dipped in tepid water to bring it more nearly to the temperature of the mouth. Chilling the model undoubtedly causes it to shrink and warp slightly but it will return to normal size and shape upon being brought to what may be called a tepid temperature — tepid water should also be used in mixing the investment. Then the case appears simply as a brass rod with a mass of investment material on the end of it (Fig. 279). The ring is about an inch in length, varying in diameter, according to the size of the casting to be made (for by this process a casting as extensive as that of a fourteen tooth bridge may be made), with a small hole in one side near the base to permit the surplus mold material to escape. The base plate is so constructed, that while it fits into the ring for a couple of millimeters there is also a flange section with a milled edge which extends beyond the side of the flask. In the center of base plate, is a dome and in the center of that there is a hole into which the sprue-former is in- serted. Having set the sprue-former in position, put the ring in place on the base plate (Fig. 280) and fill it with the mold material or investment, slowly rotating the flask as you do so. Fig. 280. 314 CONSTRUCTION OF GOLD INLAYS. Build up an excess above the top of the flask, then press a piece of glass plate down upon it which will force the excess through the little hole in the side of the flask. The glass plate is removed by sliding it across instead of lifting it. Recently Dr. Taggart has devised a new investment which may be mixed so thin that the model may be placed in the flask and the investment simply poured in upon it, a marked advantage as it sim- plifies the investing. It is not as yet upon the market, however, but will be soon. When the investment has set, the flask is heated slightly, then grasping the milled edge of the base plate it is gently turned. This breaks the adhesion of the mold material to it without disturbing the surface and the base plate and sprue-former are withdrawn from the mold. Do not invert the flask in doing this, for if this be done and some of the investment material should flake off it would drop into the sprue hole and result in a flaw in the casting. The base plate should be kept clean and polished at all times, rubbing off the surface after cleaning with a little vaseline. The base plate and sprue-former having been removed, there will be found a cup-shaped depression in the center (Fig. 281), with a hole leading to the mold. The flask is placed over the Bunsen burner in an oven which has been devised by A. C. Clark & Co., and the case heated slowly, carrying the heat to a point where the wax is ignited. The case is kept at this heat until not only has the wax been burned out, but the residual gases therefrom have also been combusted. It is highly im- portant that the mold be kept intact, to obtain a flawless casting. To insure this, heat the flask slowly and do not subject it to any greater heat than is necessary to consume the wax and its gases. Take precautions to avoid chipping the investment about the con- cavity and the sprue hole, for if these chips should fall into the mold and it frequently is impossible to remove them if they do, they cause a faulty casting and if the fault be along any of the margins, your inlay is ruined beyond repair. The burning out of the wax and its gases being completed, the flask is allowed to cool, then placed in the flask holder of the casting machine. It may be well to briefly describe the casting machine. It consists Fig. 281. CONSTRUCTION OF GOLD INLAYS. 315 of a device which holds a 100 gallon cylinder of nitrous oxide, has a pressure valve which may be set for the pressure desired, a dial pressure indicator, which registers the pressure under which the gas is released, a blow pipe, a compressing lever, a lever lock, a mold flask holder, and a signal whistle which sounds until the escape valve of the gas Fig. 282. — I. Cylinder of nitrous oxide gas. 2. Dial pressure indicator. 3 Pressure valve. 4. Signal whistle. 5. Automatic lever locking device. 7. Metal flask cover. 8. Nitrous oxide blowr pipe. 9. Mold flask. 10. Mold flask holder. 12. Nipple for illuminating gas connection. 14, 18. Flask holders, large and small, 15, ig. Base plates for flasks large and small with sprue-formers in place. 16, 17. Large and small flasks. .21. Control valve for nitrous oxide to blow pipe. * cylinder has been closed after the casting has been made, a very valuable little device by the way which prevents the inadvertent loss of a cylinder of gas (Fig. 282). The flask having been placed in the flask holder, a button of gold is placed in the cup-shaped depression of the mold and the flame of the nitrous oxide blow pipe is directed against it. The use of the nitrous oxide blow pipe concentrates a small intense flame directly upon the 3l6 CONSTRUCTION OF GOLD INLAYS. gold, melting it thoroughly without affecting the surrounding mold as the ordinary gas blow pipe flame would. The button of gold having been melted until it fairly boils, the compressing lever is brought down, thrusting aside and shutting off the blow pipe, forcing a metal cover, with asbestos rim packing to make it pressure tight, upon the flask ring and releasing upon the molten gold a gas pressure of about twelve pounds from the gas cylinder, forcing it into the mold in the center of the flask, the residual air being driven into the minute pores of the mold investment ahead of the gold. The various operations are done automatically by the downward sweep of the compressing lever. The whole operation is practically instantaneous, the molten gold has no opportunity to cool and solidify until it is forced into the mold ; the gas pressure is confined absolutely to the mass of gold and is sustained while it is cooling, and therein lies the main factor of success of this method. The flask is cooled, the investment broken out and a gold casting, the duplicate of the wax filling with a metal sprue attached is found. The metal sprue is cut off with a fine saw or pair of nippers, the gold inlay is immersed in hydrofluoric acid for a short time to remove the particles of investment material that will be found fused to it, then washed, boiled in sulphuric acid and washed again. Frequently the outer surface will need little or no polishing save at the point where the sprue was attached, so perfectly may castings be made by this process if the wax filling be carefully finished and all the various steps carefully carried out. Before attempting to try the inlay in the cavity, examine the cavity surface of the inlay carefully for little gold beads which may be readily removed with a fine sharp excavator. After trying in the inlay, if it should be found that the proximal contour is insufficient, this may be added to by simply flowing on a little 22-K solder at that point. It has been found by experience that it is best not to reheat the flask before placing it in the machine; it must be perfectly dry, however, otherwise there will be a regurgitation of steam that will either blow the gold out of the depression when it is molten or prevent the complete casting, according to the amount of steam developed and confined. Inlays should be cast the same day that the investment is made, the results are not so perfect when molds are allowed to remain over night before casting. When small inlays are to be constructed, as is often the case, in cavities in bicuspids or the anterior teeth, an ordinary pin may be used CONSTRUCTION OF GOLD INLAYS. 317 instead of the regular sprue-former, this pin is heated and the point of the pin is placed in the model while it is in the cavity of the tooth, then, after removing, a mass of wax is placed in the hole in the base- plate of the flask and the head of the pin set into it. Scrap gold should not be used for casting inlays. After many experiments the writer advises that the usual inlay be cast of an alloy of 3 parts 24k gold and one part 22k solder. If the inlay is very extensive and is to be subjected to heavy stress of mastication, cast it of an alloy of pure gold with five per cent of platinum, using a block of magnesia as a melting block instead of one of charcoal. After setting, but before the cement has hardened, burnish all margins that cannot be reached with a disk, then pohsh the margins accessible to a disk, running the disk across the margins at right angles and from the inlay towards the tooth; this spins out and burnishes down a fine margin of gold so thoroughly that after this polishing is completed no cement is visible even under a magnifying glass. As to cements for setting, the writer advises the hydraulic cements. The effectiveness of this casting device may be appreciated when you are informed that by it clasps may be perfectly cast of clasp gold. With this casting machine has been cast gold crowns upon platinum bases; bridge sections even up to those embracing the entire arch; clasps; retaining splints; partial plates; and even full plates may be cast. There is no question but what Dr. Taggart's invention of appliance and process marks a new epoch in both operative and prosthetic den- tistry; its value is such that the profession and the public are under obligation to him. Since his demonstration of appliance and process other appliances for casting have been devised and presented. One very ingenious ma- chine was originated by Dr. Jamieson, of Indianapolis. It casts by centrifugal force, the flask having a swivel handle is hung from a hook at the end of a horizontal rod about a foot long attached to an up- right rod which is revolved by the release of a spring at the rate of about 3000 revolutions a minute. Another device originated by R. C. Brophy, of Chicago, casts by suction, a partial vacuum being created. Still another device, the orig- inator of which the writer cannot ascertain, casts by means of steam pressure. A pad of moistened asbestos is jammed down upon the flask, the heat of the molten gold developing steam of sufficient pressure to force the gold into the mold. All these methods, however, are based upon that of Dr. Taggart's, in that they employ a wax filling as a model and a flask for. the mold 3l8 CONSTRUCTION OF GOLD INLAYS. identical with his, and it may be remarked that these were the most important factors of his invention, the solution of the casting device being the least difficult of the problems. The writer has tried all methods and devices for casting and after many experiences states unequivocally that Dr. Taggart's appliance has a wider scope and produces more uniform and more perfect le- sults than does any other. He holds no brief for the gentleman and is under no greater obligation to him than is any and every member of the profession. The statement is made simply because it is a fact. This process supplants all others because better results can be obtained with less labor for the operator and less loss of time for both operator and patient. Just a word of serious warning in closing this chapter to those about to employ this method. Do not imagine that it discounts care and skill. One may think it is no trick at all to construct a wax filling for a cavity, but let me assure you, and experience will emphasize it, that it requires all the skill and patience you possess most of the time to properly construct this wax filling and you will probably be discouraged with the process and your endeavors, until you have mastered the manipulative technique; for faulty wax fillings will invariably result in faulty inlays. Skill, care and cleanliness must be observed in all steps of this process. Once the manipulative technique peculiar to this process has been mastered, one will discover that instead of discounting, it puts a premium on individual skill and carefulness. For by this process more uniform and better results with less labor may be obtained than have heretofore been possible with any process at our command. CHAPTER XVIII. THE TREATMENT OF EXPOSED OR NEARLY EXPOSED PULPS. BY J. P, BUCKLEY, PH.G., D. D. S. GENERAL CONSIDERATIONS. In the practice of dentistry there are problems continually arising wherein it is difficult for the conscientious operator to decide upon a method of procedure which will conserve the best interests of the patient. There is no condition confronting us with greater difficulty than in those cases where the decay has extended to such a depth that its thor- ough removal will expose or nearly expose the pulp. The problem to be solved here in all such cases is to decide whether it will be best to try to save the pulp or to anesthetize or devitalize this organ, remove it and subsequently fill the canals. There are several important factors to be considered, and upon which will largely depend the success or failure following an attempt to save the pulp after it has actually been exposed. In an accidental exposure in the preparation of a cavity, the chances for saving the pulp, provided the injury has not been too great, are far more favorable than if the pulp had been exposed by the necessary removal of carious dentin. Our success will also depend in no small degree upon the condition of the pulp as well as upon the general condition of the mouth of the pa- tient in which the exposure occurs. If there is congestion or any evi- dence of degeneration of the structural components of the pulpal organ itself, it would be futile to attempt to cap it, as would be also any attempt to permanently save a pulp in the mouth of a patient who was suffering from some systemic derangement interfering with the general circula- tion, thus lessening vital resistance; for in such cases the pulp would fail to receive from the blood supply the necessary elements for the restoration of its functional activity. The general condition of the mouth itself and the care it receives daily from the patient, is an essen- tial factor to be taken into consideration before proceeding to cap a pulp. Dr. S. A. Hopkins, of Boston, in a carefully conducted series of experiments to ascertain the difference in virulency of certain path- ogenic bacteria in different mouths, and in the same mouth under 319 320 TREATMENT OF EXPOSED OR NEARLY EXPOSED PULP. diflferent conditions, proved that not only did the germs proliferate more rapidly in neglected and uncared-for mouths, but their pathogenic properties are greatly increased. There is one class of cases of pulp exposure which frequently pre- sents in a busy practice and in which it is our plain duty to make the attempt to restore the organ to its normal function, even though the conditions for doing so are not altogether favorable. I mean here those cases in the mouths of young patients where the pulp is exposed from decay and the roots of the tooth have not been fully developed. Every effort should be made to cap such a pulp and thereby save it, if for only a year or two, for clinical experience has demonstrated that to remove the pulp and properly close the large openings in the end of the roots is, at best, a difficult procedure; that a tooth in this condi- tion, thus treated, is usually a source of annoyance and its usefulness generally of short duration. In another class of cases the author also believes that we are justi- fied in capping the pulp. For instance, in those cases of exposure where for certain reasons it is desirable to save the tooth, and on which it would be difficult to adjust the rubber dam, aseptically remove the pulp and thoroughly fill the canals. I wish to state here, however, that I do not mean to infer that a pulp should be capped in an anterior tooth, because of the liability of the tooth structure discoloring after the pulp has been removed. This phase of the subject will be referred to in detail in a subsequent chapter on pulp removal under the preservation of the color of the tooth. From the foregoing, then, it should readily be understood that no set of rules can be given, the application of which will surely lead to success. Every case must be studied and treated according to the operator's best judgment after having taken into consideration all these various factors. CAPPING THE PULP. There are several methods of capping the pulp, each differing in minor details, such as the use of various cements, gutta-percha, con- cave metallic discs, etc., etc. In the remainder of this chapter attention will be directed to the general precautions to be taken in following the different methods of capping; after which one method will be described in detail which has proved successful in the author's practice. By this I do not mean to convey the idea that all pulps which I have at- tempted to save have been rehabilitated to their functional activity — many have not; however, a sufficient number of those thus treated have CAPPING THE PULP. 32 1 remained quiet, and proved years later to be vital, to justify making the attempt where the case demands. Precautions. — The precautions to be observed in following any method are: (i) By the use of an anodyne, the hyperemic pulp, if in this con- dition, must he restored to normal before the final capping. (2) The dentin overlying the pulp must he thoroughly sterilized. It should be noted here that the usual perfunctory method of sterilizing the dentin by simply applying a germicidal solution to the cavity for a few moments does not sterilize to the degree necessary for successful results. The lack of thorough sterilization has, without doubt, been the chief cause of failure. The accuracy of this statement will be seen when we remember that our greatest success has followed the capping of pulps which have been accidentally exposed with a bur or instru- ment in preparing a cavity, although, in most cases, greater mechanical injury had been caused than when the exposure was due to caries or the removal of carious dentin. (3) Pressure in applying the material for capping, or the cement which covers the capping, must he avoided. Technique. — After breaking down all overhanging edges of enamel and removing as much of the debris and softened dentin as can be done without pain or injury to the pulp, the cavity should be flooded with a mild, non-irritating, antiseptic solution, previously heated to the tem- perature of the body. For this purpose the author suggests the use of peppermint water to which 95 per cent phenol has been added in the following proportion: I^ Phenolis, f.3 j Aquae menthae piperitae, f § vj — M. Sig. — Use wherever a mild, non-irritating antiseptic solution is indicated. This solution can be further diluted, if necessary, and used with a water syringe, before applying the rubber dam, thus adding comfort and cleanliness to the operation. The excess can now be absorbed from the cavity with cotton and the dam adjusted. By using some obtund- ing remedy ami a sharp spoon excavator, or oftentimes a large round bur in the engine, the carious dentin can be removed. If, however, the thorough removal of all the softened dentin would make a large exposure, it is best to leave the layer overlying the pulp and depend upon the sterilizing agent, rather than to jeopardize the life of this organ by the injury thus produced. The delicate pulp tissue will not tolerate much abuse and remain quiet, therefore if it is injured to any 32 2 TREATMENT OF EXPOSED OR NEARLY EXPOSED PULP great extent it had better be removed at once. The dentin can now be sterilized by sealing in the cavity, for a week or two, the following remedy which is not only germicidal in action, but possesses marked anodyne properties as well: I^ — Menthol, gr. xx Thymol, gr. xl Phenolis, (U. S. P.) f.3 iij— M. Heat the phenol and then carefully add the menthol and thymol. Sig. — Use as directed This remedy is known as the author's phenol compound. It is best to seal with a veneer of quick-setting cement, previously filling most of the cavity with cotton, thereby avoiding pressure and facilitating the subsequent removal of the dressing. By this means the dentin can be thoroughly sterilized, and the pulp, if at all hyperemic, as it is likely to be, will return to its normal condition. Thymol has a peculiar but favorable action on animal tissue, and for this reason it is incorporated in the prescription. At the next sitting, the case giving a favorable history for the interval, the dam should always be applied, the teeth included sterilized and the previous dressing carefully removed, when the exposure and dentin immediately over the pulp can be gently covered with a thin paste made by mixing pure precipitated calcium phosphate with phenol compound, oil of cloves, or eugenol. The paste should be placed on one side of the cavity and gently coaxed over the exposure in such a manner as to exclude the air. I desire to emphasize the importance of covering the entire dentin immediately over the pulp, as well as the exposure, with this antiseptic and non-irritating paste. By this means we prevent the phosphoric acid of the cement, used to cover the paste and to temporarily fill the cavity, from irritating the pulp. It is best, as intimated here, to fill the entire cavity with cement and wait for a few months or perhaps a year before inserting the permanent filling or inlay. Advantage should be taken of every possible means of pre- venting subsequent irritation to the pulp. For this reason largely the author uses precipitated calcium phosphate instead of calcined zinc oxid, which latter substance is recommended by many writers. The powder (largely zinc oxid) which comes with a package of cement is supposed to be chemically pure. Those who are familiar with the science of chemistry, however, know that arsenic is found associated in nature with many of the metals, among which is zinc; and, while it can be done, it is difiicult to obtain these metals or their oxids free from CAPPING THE PULP. 323 arsenic. It is well, especially in those cases where the pulp is not quite exposed, to add a small amount of either aristol or europhen to the paste. These are iodin compounds and are used as substitutes for iodoform. Both are tasteless, practically without odor, and insoluble in water, but soluble in the oil used as the vehicle for the paste, there- fore only a small amount should be added. In closing this chapter, I desire to emphasize the importance of studying carefully the conditions as found in each case; and to say that the opportunity here for exercising good judgment is very great, and that there is a satisfaction in realizing, whether we succeed or fail in our effort to save the pulp, that we did our duty as we saw it. CHAPTER XIX. THE ANESTHETIZATION AND DEVITALIZATION OF PULPS, THEIR REMOVAL, AND THE SUBSEQUENT TREATMENT. BY J. P. BUCKLEY, PH.G., D. D. S. GENERAL CONSIDERATIONS. Embryologists claim that when the roots of a tooth are fully devel- oped, the pulp has no further function to perform. If this theory can be accepted as correct, and I think that it is quite well established, it would appear from the large percentage of failures following the most careful methods of pulp capping, that the safest, and, therefore, the best practice would be to destroy the vitality and remove the pulp in all cases where this delicate and susceptible tissue had been previously irritated for any great length of time, unless, as explained in the fore- going chapter, there was some special reason for attempting to restore the organ to its functional activity. From sad past experience the author has been led to adopt this general practice. By this I do not wish to convey the idea that it is advisable or necessary to miscellane- ously or ruthlessly destroy pulps, for such is not the case. It is the plain duty of every dental practitioner to save th,e pulps of teeth, if it can be done with any reasonable degree of success. Dentists are delving into pathology today more than ever before; and a knowledge of the pathology of the pulp, whereby one may be able to interpret the clinical symptoms, is essential in arriving at a proper decision as to whether the pulp should be saved or destroyed. There are many conditions, however, which necessitate the removal of the pulp, such as: (i) Dental caries, or the invasion of pathogenic bacteria and the absorption of toxins. This is the most prolific source of pulp irrita- tion. (2) Mechanical irritation, due to such causes as abrasion, thermal changes, close proximity of metallic fillings, injudicious regulating, excessive grinding, etc. (3) Calcific deposits, or pulp nodules within the pulp itself. These calcific bodies result from slight but continued irritation of the pulpal organ. (4) Crowning teeth and filling large cavities. It is usually diffi- 325 326 THE ANESTHETIZATION AND DEVITALIZATION OF PULPS. cult to grind a vital tooth sufficiently to adjust the band for a crown properly, without irritating the pulp and thus endangering its life. Sometimes in filling teeth it is advisable to remove the pulp in order to properly anchor a large filling or inlay. (5) Pyorrhea alveolaris. Frequently in treating this disease the best results can be accomplished by removing the pulp and thereby throwing the entire circulation to the sluggish pericemental mem- brane. Factors to he Observed in Removal 0} Pulp. — Having considered all of the conditions and deciding that the removal of the pulp is in- dicated, the method by which this can be accomplished with the least inconvenience to the patient and to the operator is the most important consideration. Whatever method is employed in the removal of pulps from teeth and the subsequent treatment, there are at least three fac- tors to be observed, viz.: (i) Establish and maintain asepsis in performing the operation. (2) Preserve the color of the tooth. (3) Thoroughly fill the root. METHODS. I. Anesthetization. — In the author's opinion a very satisfactory method of removing pulps from teeth, to both patient and operator, all things considered and conditions being favorable, is to anesthetize the tissue by the use of various strength solutions of local anesthetic agents. The solutions are forced or carried through the dentin and into the pulp by means of pressure or the electric current. (i) Pressure Anesthesia. — By pressure anesthesia is meant the process of anesthetizing the pulp by forcing solutions of local anesthetics, usually cocain hydrochlorid, into the tissue by means of pressure. The pressure is applied either by using unvulcanized rubber or gutta percha, and a blunt instrument, or by specially devised instruments for this purpose. There are many such instruments on the market ; and while they are often an aid in accomplishing the ultimate result, they are not an absolute necessity. The rubber dam should be employed in every case where it is pos- sible to adjust it, and the teeth included sterilized. In cases where the dam cannot be adjusted, it would doubtless be best to remove the pulp by the devitalization method, to which reference will be made later in this chapter, for in using the method under consideration care must be taken to prevent pericementitis following the operation; and one of the precautions to be observed in preventing this result is to thoroughly METHODS. 327 sterilize the cavity before applying the pressure. It should be remem- bered that the majority of canals which contain live pulps are sterile, generally speaking, and if they become septic at any time before the root is filled, it is the fault of the operator. Thus the importance of always adjusting the rubber dam, using sterile instruments, and having in a convenient and conspicuous place an aseptic doily on which to wipe the blood and dry the instruments used. Attention is again directed to the fact that the usual custom of apply- ing coagulating agents, such as phenol, cresol, etc., to the cavity for a few seconds, does not sterilize the dentin to the degree desired. The best results are accomplished by employing germicidal agents which are soluble in water. In cavities where the decay is not too deep, the den- tin can be sterilized by the use of a 10 per cent solution of formaldehyd to which 5 per cent of sodium borate (borax) or sodium carbonate has been added. Where the decay is near the pulp this solution is liable to cause pain, in which case the same result can be accomplished by the use of a 1:500 solution of mercury bichlorid. In using the latter solution the pliers on which the remedy is applied should be wiped immediately on an aseptic doily to prevent the mercury from acting upon the instrument. One of the best solutions with which to chemically sterilize the dentin, especially in those cases where the cavity has previously been filled and the tubuli are closed and per- haps there is secondary dentin, is a 25 per cent solution of sulphuric acid. Dr. Geo. W. Cook, of Chicago, recommends using pure sul- phuric acid for this purpose. The solution can be applied to the floor of the cavity, being careful not to get the agent on the crown of the tooth. After a few minutes the excess can be neutralized with a solu- tion of sodium bicarbonate. After the dentin is sterilized the cavity should be desiccated with warm alcohol and gentle heat, when we are ready to use the anesthetizing solution. Before taking up the technique of this method, however, I desire to emphasize the importance and necessity of cavity sterilization. In our discussion later of the devitali- zation method, it will be pointed out that the carious and infected dentin can be completely and painlessly removed after the devital'zing agent has been applied, thus mechanically sterilizing the cavit} ; but in the anesthetization method the infected dentin is sensitive and can- not be removed without unnecessarily producing pain. The dentin in this case must, then, be sterilized by chemical means, for to force the anesthetizing solution through the dentin without previously ster- ilizing it, means the forcing of microorganisms, and perhaps poisonous ptomains, into the pulp tissue and many times into the tissue surround- 328 THE ANESTHETIZATION AND DEVITALIZATION OF PULPS. ing the apical end of the root, for it is difficult to force the solution to, and only to, the apex; thus too much pressure and the lack of thorough sterilization constitute a prolific source of pericementitis following the removal of pulps by this method. With the cavity thoroughly sterilized we are now ready to use the anesthetizing solution, which should be made at the time. For this purpose the crystals of cocain hydrochlorid, previously powdered, should be used as the base, and freshly distilled or boiled water as the vehicle. In my own practice I use cocain hydrochlorid points as the base and my regular local anesthetic solution as the vehicle for making the stronger solution. A prescription for the regular local anesthetic solution here follows: I^ — Cocainae hydrochloridi, gr. vj Phenolis, m. ij Sodii chloridi, gr. j Aquae menthae piperitae, f. § j — M. Sig. — Use as a local anesthetic for hypodermic injections. The cocain hydrochlorid points not only insure a pure specimen of the drug, but facilitate making the solution, as they are so read- ily soluble. There is no advantage in using the above solution over distilled or boiled water or freshly prepared peppermint water, except that the solution is always at hand in a convenient container and is sterile. The thumb and forefinger with which cotton is to be wrapped around the broach should be sterilized by dipping a large pledget of cotton in the 10 per cent formaldehyd or i : 500 mercury bichlorid solution and rolling this between the thumb and finger. A small amount of the alkaloidal salt is now placed on a clean glass slab and a pledget of cotton, dipped in the vehicle selected, a few drops of which have previously been placed on one end of the glass slab or in a clean glass watch crystal or other container, is gently placed in contact with the drug, when the latter readily dissolves, making a strong solution. It is never necessary to make a saturated solution, for oftentimes better results will be obtained, especially if the solution is to be forced through the dentin, if the strength of the solution approximates only 4 or 5 per cent. The cotton thus saturated is placed in the cavity as nearly over the pulp as possible. A piece of unvulcanized rubber which will approx- imately fill the cavity is selected and passed through the flame. There are two objects in doing this: It sterilizes the rubber, and also makes it more pliable in which form it conforms readily to the cavity of the tooth. The rubber is now placed in the cavity, and by means of METHODS. 329 gentle but firm pressure with a suitable blunt instrument the solution is forced through the dentin and into the pulp. If there is any evidence of pain as the pressure is applied, it should be stopped for a moment, but never released. The slight pain is only momentary and is an in- dication that the solution is bemg confined under the pressure, which is essential for the success of this method. In lower teeth, or other favorable cases, a cocain hydrochlorid point may be placed directly in the cavity and the moist cotton added, making the solution therein. It may be necessary in those cases where there is considerable dentin between the cavity and tlie pulp to make two or three applications before the pulp is reached without pain, after which one application should complete the thorough anesthetization of the organ. After the first application a small depression can be drilled into the dentin toward the pulp, in which the solution can subsequently be placed, thereby aiding materially in confining the solution under the pressure. When an ex- posure exists it requires but little pressure to anesthetize the pulp. In these cases the cocain hydrochlorid can be placed in the cavity near or over the exposure and the pulp gently pricked with a sharp explorer, causing it to bleed; this if done carefully will produce very little pain. The blood will dissolve the cocain hydrochlorid, when pressure can be applied and the pulp anesthetized. In doing this, however, there is greater danger of forcing the blood into the tubuli of the dentin of the crown of the tooth, thereby making it more difficult to remove the blood. Care should also be taken not to force the solution any further than is necessary for the painless removal of the pulp, for it should be noted here again that cocain is a general protoplasmic poison, and if even weak and sterile solutions are forced past the apices of the roots peri- cementitis is almost sure to follow. When the pulp is anesthetized the pulp chamber should be opened into in such a manner as to expose the canals. This is best accom- plished with a large round or inlay bur by means of which the entire roof of the chamber can be obliterated. In opening into the pulp chamber of molar teeth care should be taken not to disturb the floor of the chamber, for by so doing we are liable to add to the difficulty of entering the canals with a broach. While we are never justified in drilling unnecessarily for the purpose of freely exposing the canals, it is, if necessary, far better to weaken the crown of the tooth somewhat by this means rather than leave a portion of the pulp in an inaccessible canal which may decompose and subsequently cause an abscess. The selection of a proper broach is an important matter. Every broach should be tested before entering the canal. This can be done 330 THE ANESTHETIZATION AND DEVITALIZATION OF PULPS. by bending it in various directions. If the broach is weak in any particular place it can be detected by this means; thus we avoid break- ing the broach in the canal, the removal of which is often a difficult procedure. Many good operators claim to be able to remove all pulps by using a smooth, three-cornered broach on which a few threads of cotton are wound. Others use twist or spiral broaches. In all large canals the author has had the most satisfaction from the use of a barbed broach. The broach should be gently worked along the side of the canal as far as it will go without using too much force, twisted once or twice to entangle the pulp, and then withdrawn. By this means the pulp can be removed from large canals in its entirety. In the removal of live pulps by the anesthetization method, there necessarily would be more hemorrhage than in those cases where the pulp was devitalized before attempting to remove it. However, the control of hemorrhage is not as difficult a procedure as many writers have led us to believe. In most cases the hemorrhage, if undisturbed, will be checked by nature's method in a few minutes; after which the blood in the cavity and canal should be thoroughly removed. I desire here to emphasize the importance of removing the blood. One of the factors to be observed in extirpating pulps from teeth and the subse- quent treatment, is to preserve the color of the tooth. The cause of many teeth darkening after the pulp has been removed, can be traced directly to the failure to remove the blood from the dentin of the crown of the tooth. The far too prevalent practice of wiping out the bloody canal with a solution of hydrogen dioxid, blindly thinking the blood can be removed by this means, cannot be too strongly condemned. The hydrogen dioxid simply decomposes the blood within the tooth structure, oxidizing the iron of the hemoglobin; and the gases evolved in the decomposition force this pigment into the tubuli, which, if left (and it is difficult to remove it), will cause the tooth to subsequently darken in almost every instance. In a subsequent chapter the author expects to show that ferric oxid is largely responsible for the discolora- tion of teeth from pulp decomposition. Therefore we should avoid forming within the tooth structure the pigment which we know will dis- color teeth. The color of a tooth does not depend upon the life and vi- tality of the pulp, but upon the array of colors in the dentin which are re- flected through the nearly colorless and transparent enamel. If, then, these colors are not changed by our failure to remove the blood or by the use of staining remedial agents in the subsequent treatment following pulp removal, the tooth will not discolor. To remove the blood from the canal, alcohol can be used, or even METHODS. 331 better than this agent is nature's greatest solvent, water. ' The water should, of course, be sterile, and the same specimen can be employed here as was used in making the anesthetizing solution, i. e., freshly distilled or boiled water, or peppermint water to which two minims of phenol has been added to the fluid ounce. If convenient, a little sodium chlorid (common salt) can be added to the water. Phys- iologic salt solution (normal saline) is an excellent solution to use for this purpose. By this means the blood can be completely removed, not decomposed in the canal and forced into the structure of the tooth. There are many canals so small and tortuous that even a fine broach will not enter, to any depth at least. In these cases, after the hemorrhage from the larger canals has been checked and the blood re- moved, the pulp tissue in the small canals can be disorganized by the use of strong solutions of mineral acids or alkalies. The author pre- fers making a paste of sodium dioxid and absolute alcohol, placing the paste in the pulp chamber over the small canals, and working it down as far as possible with a smooth broach. The alcohol gradually evap- orates, when the sodium dioxid can be decomposed into oxygen and caustic soda by placing a pledget of cotton in the cavity moistened with distilled water. After the reaction has taken place, the alkali can be neutralized with a weak solution of sulphuric acid (2 per cent). This process can be repeated until the desired end is attained. There are other means by which the same result can be accomplished, such as the use of pure phenolsulphonic acid, a 50 per cent solution of chem- ically pure sulphuric acid, strong solutions of sodium or potassium hydroxid, or a mixture of metallic sodium and potassium (Schreier's paste). These same agents, especially the phenolsulphonic acid, can be used to advantage for the purpose of disposing of a remnant of a pulp in larger canals. It is not safe to anesthetize this remnant by means of pressure. The only cases on record to my knowledge, where toxic symptoms have resulted from the removal of a pulp by pressure anesthesia, followed an attempt to anesthetize a remnant of a pulp or in making the second apphcation of the anesthetizing solution. After the pulp has been removed and the canals dehydrated with alcohol and heat, an anodyne treatment is indicated. For this purpose such drugs as phenol, oil of cloves, or eugenol can be employed. The author suggests here the phenol compound to which attention was called in the chapter on The Treatment of Exposed or Nearly Ex- posed Pulps. In using any of these remedies, especially the last named, it is best to insert dry cotton in the canal and then place a pledget dipped in the remedy in the pulp chamber and seal with tem- 332 THE ANESTHETIZATION AND DEVITALIZATION OF PULPS. porary stopping or cement. The dry cotton in the canal will absorb the moisture from the apical end of the root and the anodyne remedy from the pulp chamber. There is an advantage in using the dry cotton, for it is almost impossible to completely dehydrate the canal at this sitting. If asepsis has been maintained in removing the, pulp all that is necessary is to keep the canal in this condition until the root can be filled. The canals should not be filled at the sitting at which the pulp has been removed by pressure anesthesia unless there be some excep- tional reason for doing so. There are many good reasons why the canal should not be filled at this sitting: (i) While it is our object to force the solution just sufl&ciently to anes- thetize the pulp, our main object is to remove the pulp absolutely without pain, and it is very difficult to force the solution to the end of the root without forcing it through the apex and anesthetizing the tissue in the apical area to some extent. With the tissue anes- thetized we would have no guide as to when the root was thoroughly filled. (2) The tearing away of the pulp from its connection at the apex causes more or less irritation, and a few days should elapse to give nature a chance to readjust the condition. The root filling would only serve at this time to further irritate the tissues. (3) Sometimes with the utmost care in removing the pulp, secondary hemorrhage ensues with the formation of a clot in the apical area, causing soreness, in which case greater comfort can be given the patient by the proper treatment through the root canal than simply by counterirritation or external treatment only. At the second sitting, the case giving a favorable history, the canals should be filled. There are cases occasionally where nature does not stop the hemor- rhage as readily as we desire. In these exceptional cases the hemorrhage must be stopped by artificial means, even at the possible expense of producing pericementitis. Cauterizing agents are useful here. For this purpose 95 per cent phenol, a 50 per cent solution of phenolsul- phonic acid, or a 15 per cent solution of trichloracetic acid, can be worked down into the canal against the injured and bleeding tissue, after which the anodyne treatment is employed as usual. Where the above treatment does not produce the desired result, cotton saturated with a fresh 1:1000 solution of adrenalin chlorid can be placed in the canal and with unvulcanized rubber forced into the tissue beyond the end of the root. This should only be used in extreme cases because of the soreness it is liable to produce. METHODS. 333 In this connection I desire to discuss the use of solutions of adren- alin chlorid as the vehicle for making the anesthetizing solution, or the use of adrenalin chlorid and cocain hydrochlorid tablets for anes- thetizing the pulp. The adrenalin chlorid has been suggested as a means of preventing hemorrhage. Now, it ought to be evident to any one who has studied this subject that to prevent hemorrhage by the use of any hemostatic agent, it is necessary to force the agent into the tissue from which the hemorrhage comes. Therefore, to get the eflfect of the adrenalin chlorid in removing pulps by pressure anesthe- sia, it is absolutely essential that the anesthetizing solution which also contains the hemostatic agent, be forced through the apex and into the apical area — the very thing we have been taught, from sad experience, not to do. When we remember that the majority of pulps we are called upon to remove are those in which there is, or has been, more or less pulpitis, and when we remember also that pathology teaches that this condition is frequently associated with pericementitis, it is questionable whether or not we ought to prevent hemorrhage in removing pulps from teeth. For to permit the escape of blood from the hyperemic tissue at the end of the root, is one of the best means of aiding nature to readjust the abnormal to the normal condition. In case the primary hemorrhage has been prevented by the use of hemostatic agents, such as adrenalin chlorid, secondary hemorrhage is almost certain to follow with the formation of a clot, the absorption of which in the apical area is an extremely slow and tedious process. In removing pulps by pressure anesthesia without employing in- struments devised for this purpose, the best results are obtained in cases where there are four walls to the cavity, for in this condition the solution is easily confined under the pressure. In proximo-occlusal cavities, the missing wall can be built temporarily with gutta-percha or cement. This is seldom necessary, however, if, in packing the rubber in the cavity, care be taken to cover the gingival wall first and thus seal at this point, then working the rubber over the occlusal and gradually creating the pressure. Whatever means is adopted for the purpose of confining the solution, we must avoid having the solution escape at the gingival margin of the cavity and thereby be forced into the gum tissue and pericemental membrane. The cause of many sore teeth following this method of removing pulps can be traced to care- lessness or ignorance in this regard. As stated elsewhere in this chapter, there are many ingeniously devised instruments on the market, the use of which is often a material aid in confining the solution under 334 THE ANESTHETIZATION AND DEVITALIZATION OF PULPS. pressure and forcing it through the dentin. The same precautions should be observed in using any of these instruments as have been emphasized in the application of pressure by other means. (2) Cataphoresis. — Cataphorcsis is a term applied to the process of carrying medicinal agents in solution into the various tissues and organs of the body by means of the electric current. In years past there were a variety of cataphoric outfits on the market. Today the method is practically obsolete. To anesthetize a pulp by this means the tooth should be insulated by the rubber dam, care being taken that no moisture escapes from the gum. A small pledget of cotton saturated with the anesthetizing solution is now placed in the cavity, the positive electrode applied to the solution, and the negative elec- trode, moistened with water, applied to some part of the patient's body, usually the hand, thus completing the circuit. A steady and con- tinuous current is desired and the perfected instruments are so devised that the amount of current can be measured. The time required to anesthetize the pulp by this means depends largely upon the density of the dentin and the perfection of the instruments used. With the pulp anesthetized, the same method of removing and the subsequent treatment is followed as in pressure anesthesia. Cataphoresis, while successful in the hands of those who mastered the technique, never became popular, largely because of the time required to accomplish the result and because of the complicated and expensive apparatus necessary. If the method of anesthetizing the pulp be followed and the pre- cautions observed as detailed in this chapter, it will be found that there are few pulps which will not yield to the influence of cocain hy- drochlorid. It takes time, however, to adjust the rubber dam, ster- ilize the cavity, remove the pulp and blood from the canal and seal in the anodyne remedy. Many times the operator is not able at this sit- ting to give the necessary time to complete this operation. There are cases also where the condition or the location of the tooth in the mouth is such as to make the removal of the pulp more favorable by another method which will now be considered. II. Devitalization. — In the chapter on The Treatment of Sensi- tive Dentin under the subject of escharotics or caustics, reference was made to the fact that there were many drugs belonging to this class of agents that could not be employed in the treatment of sensitive dentin, for the reason that they were penetrating and had the same deleterious effect upon the cells of the pulp tissue as upon the dentinal fibrillae. Some of the agents which cannot be used for allaying the sensitiveness METHODS. 335 of dentin are exceedingly valuable and are employed for the purpose of destroying the vitality of the pulp, thus aiding in its painless removal. The most prominent of these agents is arsenic trioxid, (AS2O3), formerly called arsenious acid. The author is again gratified to know that the latest edition of the United States Pharmacopeia recognizes this agent by its correct chemical name, for he was never able to understand why a true oxid should be called an acid by our legal authority. Ar- senic trioxid was introduced to the dental profession in about 1836 by a Dr. Spooner, of Montreal. The agent was first advocated to be used in the treatment of sensitive dentin; for Dr. Spooner discovered that by sealing the drug in a cavity for a few days the most sensitive dentin yielded to its influence. The fact, however, that nearly all teeth thus treated subsequently gave trouble because of the death of the pulp and the usual sequelse, led the profession to abandon this agent for the purpose for which it was introduced; but it has ever since been used as a means of destroying the vitality of the pulp. In fact, for years it was the only agent employed with any satisfaction. There has been much difficulty experienced in the use of arsenic trioxid, largely because of the uncertainty of the preparations employed. Many arsenical preparations are on the market. The white powder can be used by moistening a small pledget of cotton with some liquid, such as phenol, cresol, creosote, or oil of cloves, then by touching the cotton to the powdered arsenic trioxid, a sufficient amount will adhere which should be transferred to the cavity and sealed, preferably with cement. It is well for each operator to select an arsenical preparation with which he can obtain good results, and then this should be used to the exclusion of all others. By this means only can we become thoroughly familiar with the action of the preparation employed. The author prefers fiber made from a paste, a formula for which is here given: I^ — Arseni trioxidi, 3 j Cocainae, gr. xx Thymolis, gr. v Lanolini, q. s. ft. thin paste — M. Sig. — Apply a small amount to the dentin immediately over the pulp. Note: It is best to color the fiber red or pink with some stable coloring pigment. I wish to state here something about the pharmacy of this pre- scription; for if the preparation does not work satisfactorily, it has not been properly compounded. Arsenic trioxid is the base, cocain is a local anesthetic, and when applied to the pulp produces a condition of 336 THE ANESTHETIZATION AND DEVITALIZATION OF PULPS. analgesia by which the irritating action of the arsenic trioxid is without efifect, and thus prevents the tooth from aching while the pulp is being devitalized. With the fatty or oily vehicle, lanolin, it is best to use the alkaloid, cocain, rather than the alkaloidal salt, cocain hydrochlorid; and the less the amount of lanolin used the better will be the action of the base. For this reason largely thymol is added. There is a suffi- cient, amount of water in the lanolin to liquefy the crystals of thymol, therefore it requires but a small amount of lanolin to make a paste out of the arsenic trioxid and cocain. In those cases where the tooth has ached before the patient presents for treatment, it is always the best practice to allay the pain for at least twenty-four hours before attempting to devitalize the pulp. In any case, whether the tooth has ached or not, before applying the arsenical preparation or before adjusting the rubber dam, it is best to break down all overhanging edges of enamel and carefully remove or wash out with a non-irritating antiseptic solution any food-stufifs or debris which may be in the cavity. Food-stuffs contain albumin, and if such is in the cavity of the tooth when the arsenical preparation is applied, the arsenic trioxid will act upon the albumin, forming the arsenic albuminate, and thereby a certain amount of the agent is neutralized or becomes inert. As much of the carious dentin should also be re- moved as can be done without producing pain, for the application should be made to a sensitive spot in the cavity. It is never necessary to have an exposure of the pulp; and in case an exposure exists, it is best to apply the preparation to the dentin immediately over the pulp, rather than directly to the organ itself. The preparation should be covered with cotton or small metallic or paper disc to prevent pres- sure and also to prevent the phosphoric acid of the cement from com- ing in contact with the ingredients of the paste. There are at least four factors which govern the length of time an arsenical application should remain sealed within a tooth, viz.: (i) The age and general condition of the patient. (2) The general condition of the pulp itself. (3) The amount and condition of the dentin intervening between the pulp proper and the application of the paste. (4) The climate or season of the year, strange as it may seem, influences the action of arsenic trioxid. Taking into consideration these various factors, the arsenical prep- aration should remain in the cavity from two to six days. At the second sitting the rubber dam should be adjusted, the teeth included METHODS. 337 sterilized, and the cement and paste removed, after which every surface of the cavity should be freshened with a large round bur. This not only insures the thorough removal of the arsenical paste, which, should a portion remain, is liable to produce pericemental inflammation, but it also mechanically sterilizes the cavity by removing the carious and infected dentin. This is important and is an aid in maintaining asep- sis in the removal of the pulp. In the author's judgment this is much better practice than to depend upon a solution of dialysed iron to neu- tralize the arsenic trioxid. The pulp chamber can now be opened into and the pulp removed, observing practically the same details as explained under the anes- thetization method. Oftentimes in the initial opening into the pulp chamber, and sometimes on entering the canal, after the application of arsenic trioxid, the patient will experience some pain; but by gently working the broach up the side of the root, very little, if any, pain need be produced in removing the pulp, provided, of course, the tissue is devitalized. However, should pain be experienced, it is best to seal formocresol in the cavity in contact 'with the tissue from three to six days, when it can be removed without pain. In connection with the preservation of the color of the tooth, under the anesthetization method the author stated his objection to the use of hydrogen dioxid for removing the blood from the cavity and canal. It is necessary here also to refer briefly to a well-established practice of treating teeth after the pulps have been devitalized. Heretofore it was the practice of many dentists, after removing the arsenical dressing, to flood the cavity with a solution of dialyzed iron, after which the pulp chamber was opened into, usually producing some hemorrhage; then without any especial effort being made to remove the dialyzed iron or blood, tannic acid in some form was sealed in contact with the pulp for a week or ten days, thinking it advantageous by this means to constringe and toughen the tissue before attempting its removal. Let us consider the rationalism of such treatment. The pulp tissue in all large canals is sufficiently tough to be removed in its entirety, and it must be disorgan- ized or removed piecemeal in small canals, whether it has been previ- ously constringed or not. Hence, there is no advantage in using tannic acid and there is a serious objection. If those who follow this practice are observing, they will notice that after removing the tannic acid dressing, the pulp tissue is dark in appearance. They will also ob- serve that many teeth thus treated subsequently discolor. The cause for this is found in the fact that tannic acid and iron, in any form, are chemically incompatible, the resulting compound being iron tannate, 338 THE ANESTHETIZATION AND DEVITALIZATION OF PULPS. one of the most insoluble substances known to chemistry. In the presence of moisture a form of ink is produced which is a great staining agent for dentin, and one that is almost impossible to remove by any known process of bleaching. As has been stated elsewhere in this chapter, there are cases where, for want of time or other reasons, the pulp can be removed to advantage by devitalization; however, when this method is followed tannic acid should not be used, and every trace of dialysed iron (if used at all, and it is unnecessary to use it) and blood should be removed with alcohol or water. In those cases where we are certain that the pulp is all re- moved and where the canals can be thoroughly dried, the root filling can be inserted at the same sitting, provided there are no symptoms of pericementitis in the apical area. There are many good reasons, how- ever, for not filling the root at this time, some of which have been considered under the anesthetization method. Complications. — In our discussion thus far of the methods of re- moving pulps from teeth, we have considered only favorable cases, selecting the method best adapted to the case at hand. There are many instances, however, where it is difficult to remove the pulp by either the anesthetization or devitalization method, at least until the tooth is placed in a more favorable condition. Oftentimes in approximating cavities the decay in one or both teeth has extended far beneath the gum, the rough gingival margin of the cavity acting as a slight irritant by which the gum tissue is stimulated, causing it to proliferate until it fills a portion of, and in some instances the entire, cavity. In such cases the first consideration is to dispose of the hypertrophied tissue. Where the gum fills only a portion of the cavity and the pulp of the tooth is not causing trouble, the cavity should first be enlarged and washed with a warm antiseptic solution, after which it should be dried as well as possible and packed with warm gutta-percha. But in those cases where the gum tissue occupies the entire cavity, and especially where the tooth is aching, it should be removed at once. This is best accomplished by the electric cautery, as it disposes of the tissue, pain- lessly and without hemorrhage. In the absence of the electric cautery other means must be employed. Hypertrophied gum tissue is quite tough and fibrous, and if it is elevated or pushed back by means of a flat instrument, it will usually be found that the attachment at the gin- gival margin is small and can easily be severed by employing gum scissors or a lancet, previously dipped in phenol. It is best not to tell the patient what you are going to do, for scarcely any pain METHODS. 339 will be experienced. The hemorrhage in these cases is usually pro- fuse, but can readily be stopped by cauterization with 95 per cent phenol, a 50 per cent solution of phenolsulphonic acid, or a 15 per cent solution of trichloracetic acid. The blood should now be thor- oughly removed, the cavity dried, moistened with eucalyptol and packed with gutta-percha, letting it extend buccally and lingually to fill the interproximal space. The gutta-percha can be removed from the interior of the cavity with a heated flat instrument. Quite often the most practical way of adjusting the rubber dam in these cases is to place the clamp on the tooth posterior to the one thus packed, having a single hole in the dam include both teeth. The packing, if properly placed, filling the embrasure on either side, will prevent leakage. The pulp can now be removed by the method which the operator deems the most feasible. There is one instance in the removal of pulps from teeth, where students particularly are liable to make a serious mistake if they are not extremely careful. That is in cases where, in large occlusal cavities, especially in lower firs^ molars of children, the pulp has died and the decay has extended through the bifurcation of the roots, leaving rough edges which continually irritate the tissue, causing it to proliferate and ultimately fill the cavity. To carelessly force the anesthetizing solution into such a cavity, where the pulp in the canals is putrescent, would be the means of causing an acute alveolar abscess. The -appli- cation of arsenic trioxid would mean the loss of at least one tooth, perhaps one or two on either side of the one to which the application was made, with a portion of the alveolar process. Before applying either the anesthetizing or devitalizing agent a correct diagnosis should be made; we should ascertain definitely the kind of tissue in the cavity. With a little experience this is usually a simple matter. The history of the case as related by the patient will often serve as a guide. Pulp tissue is generally more sensitive than gum tissue, and when slightly pricked with a sharp instrument bleeds more profusely. If the tissue proves to be hypertrophied gum tissue it can be disposed of in the usual manner, the puncture closed tem- porarily with cement or gutta-percha and the tooth treated as the con- dition necessitates. When this cannot be accomplished, it is neces- sary to extract the tooth. In cases where the tissue is hypertrophied pulp tissue it will generally be found unusually resistant to both cocain hydrochlorid and arsenic trioxid, and it is sometimes necessary to resort to cauterization, using the electric cautery if possible, or employ- ing strong escharotics, such as pure phenolsulphonic acid, which is not 340 THE ANESTHETIZATION AND DEVITALIZATION OF PULPS. as painful here as would naturally be supposed, or to the administra- tion of such general anesthetics as nitrous oxid and oxygen in order to painlessly remove the tissue. Quite frequently we find cases where it seems almost impossible to force the anesthetizing solution through the dentin and into the pulp, and when arsenic trioxid is applied it has little or no effect. In these cases we can suspect that the pulp has receded because of some slight but continued external irritation and the space filled in with sec- ondary dentin, the tubuli of which are irregular and do not run at right angles to the base upon which they rest, as in the normal dentin. This condition is more often found in elderly patients. As a result also of external irritation, pulp nodules, calcific bodies of various shapes, are sometimes found within the pulp itself. Many times in removing the pulp in these cases, the most painless and best results are obtained only by a combination of both the anesthetization and de- vitalization methods; for the removal of these pulp nodules is often a difficult procedure. After we have used cocain hydrochlorid and pressure or previously applied arsenic trioxid and anesthetized or devitalized a portion of the pulp, we may be able to reach the pulp nodule or nodules without producing pain. But frequently these calcific bodies are agglutinated and close the mouth of the canal; especially is this condition found in molar teeth. The pulp tissue immediately under the nodule is extremely sensitive. In such a case the anesthetizing solution could not be forced into the canal without first removing the obstruction, and arsenic trioxid, if applied, would have no effect. These are cases which require much perseverance and patience on the part of both patient and operator. The nodule can sometimes be loosened by gently working around it with an exploring or other suitable instrument. The author has met with success by taking a small round bur and drilling past the nodule, care being taken not to puncture the root, then with the engine running rapidly the nodule is tapped and dislodged. When the obstruction in the pulp chamber and canals is removed the remaining tissue can be anesthe- tized or devitalized in the usual manner. If the devitalization method is employed the arsenical preparation can be placed over the mouth of the canal with safety; but it is never advisable to place the prepara- tion down in the canal. Nitrous oxid and oxygen analgesia will prove valuable in these stubborn cases. Arsenical Poisoning. — Before closing this chapter it may be well to consider the treatment of local poisoning by arsenic trioxid. How- ever, when such treatment is necessary it is due to carelessness on the METHODS. 341 part of the dentist or the patient, or both. It is never necessary to tell the patient what drug or remedy has been used in the treatment of teeth, many times it is advisable not to do so; but whenever an agent as destructive as arsenic trioxid is sealed within a tooth, the patient should be thoroughly impressed with the importance of keeping an appoint- ment, and of returning before the appointed time should any unto- ward symptoms develop. The patient should also be informed that the teeth thus treated might ache for a few hours, as they sometimes do, even when cocain is a constituent of the arsenical preparation; but that the aching will be of short duration. In case, however, the tooth or gum becomes sore, they should be instructed to return at once. In those cases where the arsenical preparation is not hermetically sealed within the tooth and some of it gets on the gum tissue, remaining only long enough to cause devitalization, all that is necessary is to first wash the part with an antiseptic solution, and then mechanically pick off the dead or sloughed tissue with sterile pliers until bleeding is produced, if this is possible, after which the part should be disinfected and the tissue stimulated. To disinfect the part, any good disinfectant can be used. Nothing is better here than the official 3 per cent solu- tion of hydrogen dioxid. As a means of stimulating the cells, iodin compounds are useful. The Pharmacopeia recognizes a compound solution of iodin (5 per cent) which can be applied by first drying the part. After removing the dead cissue and disinfecting, the author prefefs applying euroform paste. A prescription should also be written for an antiseptic mouth wash with which the patient should keep the mouth as clean as possible. The treatment can be repeated as often as the case necessitates; usually one or two treatments will suffice. In those severe cases where the arsenic trioxid has penetrated to and devitalized the process as well as the gum, the first treatment is surgical. After washing with an antiseptic solution, the affected proc- ess should be removed with a suitable bur in the engine. It may be necessary in extensive cases to extract the tooth, after which the treatment is practically the same as has been outlined above. Some- times there is pain following the surgical removal of the affected proc- ess. In this case the euroform paste will act as a specific absolutely controlling the pain. The case should be watched closely and the stim- ulating treatment kept up until the part has healed. The tissue in the interproximal space will never be fully reproduced, and will always be a source of more or less annoyance. It will be noted that in discussing the treatment of local arsenical poisoning, no mention has been made of dialysed iron. The'prac- 342 THE ANESTHETIZATION AND DEVITALIZATION OF PULPS. tice of applying this agent to the affected part is both useless and wrong. In closing this chapter the author desires to emphasize what was stated in the beginning, that it is the plain duty of every practitioner to study the pathology of the pulp, thus learning to read the clinical symptoms and to save the pulps of teeth in all cases where it can be done with any reasonable degree of success; yet experience and observation will soon show the folly of attempting to save a pulp that has been irri- tated for any great length of time, and will prove also that in these cases, the safest practice is to remove the pulp and subsequently fill the canal, notwithstanding the difficulty often attending the performance of this operation. CHAPTER XX. THE TREATMENT OF ORDINARY PERICEMENTITIS. BY J. P. BUCKLEY, PH. G., D. D. S. General Considerations. — It is not the intention to introduce in these chapters needless pathologic facts, yet in the treatment of pericementitis it is important to remember that the pericemental membrane is very vascular and well supplied with nerves; that it is enclosed within bony walls, and, therefore, when inflammation exists in the tissue the membrane becomes thickened, forcing the tooth from its socket. This elongation of the affected tooth is one of the chief symptoms of true pericementitis. Before discussing the therapeutics of pericementitis, I desire to indelibly impress upon the mind of the reader the fact that this con- dition is too frequently produced by carelessness on the part of dentists. It is not always possible to successfully perform dental operations without irritating the susceptible pericemental membrane; however, much of the trouble can be avoided if judgment is exercised and proper precautions are taken in treating teeth. There are at least two classes of irritants by which ordinary peri- cementitis is produced, viz.: (i) Drug irritants. (2) Mechanical irritants. The inflammation of the pericemental membrane caused from drug or mechanical irritants, will be called ordinary pericementitis in this chapter, in order to differentiate it from septic pericementitis — a condition produced by pathogenic bacteria, poisonous ptomains, and irritating gases, which have escaped from a putrescent root canal. Drug Irritants. — There are many circumstances and conditions which influence the action of drugs upon different individuals and upon the same individual under different conditions. We find cases occasionally where pulps have been removed by pressure anes- thesia, and where, seemingly at least, every precaution was taken in sterilizing the dentin, selecting a sterile anesthetizing solution and in applying the pressure; yet severe apical pericementitis follows. This may or may not be due to the drugs used in performing the operation. There are cases, too, where the pericemental membrane becomes 343 344 THE TREATMENT OF ORDINARY* PERICEMENTITIS. highly inflamed and extremely responsive from the action of arsenic trioxid, even when the drug was properly scaled within the tooth only a short time. These are conditions over which the operator seems to have no control; however, drugs are often used injudiciously. In the preceding chapter it was stated that an anodyne treatment was in- dicated after the mechanical or surgical removal of the pulp. There- fore, care should be taken to select drugs for this purpose which produce a soothing and not an irritating effect. There are some instances in dental practice where we desire to irritate and thereby stimulate the pericemental membrane; but this should be avoided here. Judgment should also be exercised in sealing in anodyne remedies, such as phenol, oil of cloves, etc., in the canals, especially in bicuspid and molar teeth, for should the temporary filling be left too full and the remedy forced through the apex by the closing of the jaws, even these agents cease to be anodynes and become irritants. Whether phenol, oil of cloves, and similar drugs or remedies are anodynes or irritants, depends largely, then, on where and how they are used. In filling root canals it is the practice of many dentists — the author among the number — to moisten the canals with eucalyptol before in- troducing chloro-percha and the gutta-percha cone. Care must be taken here to use eucalyptol and not oil of eucalyptus, unless it be the refined product. Commercial oil of eucalyptus has been the cause of many cases of apical pericementitis following the most careful filling of root canals. The eucalyptus tree produces a volatile oil which contains three constituents, each distilling over at different temperatures; the first product thus obtained is eucalyptol, hence the most volatile constituent of oil of eucalyptus and the one which is the solvent for gutta-percha. While eucalyptol is a slight irritant, it is not nearly so irritating as oil of eucalyptus. The irritat- ing property of eucalyptol can be modified and its antiseptic value in- creased by adding menthol and thymol in the following proportion: I^ — Mentholis, gr. ij Thymolis, gr. iij Eucalyptolis, f.o j — M. Sig. — Use as directed. This remedy is equally as good a solvent for gutta-percha as is euca- lyptol alone; and will be called eucalyptol compound in the following chapters. Mechanical Irritants. — The pericemental membrane is frequently, I might add too frequently, irritated by mechanical irritants, such as root canal fillings, ill-fitting partial plates, crowns and bridges, mallet- GENERAL CONSIDERATIONS. 345 ing, regulating, faulty occlusion, salivary and serumal calculus, etc. There is perhaps more pericementitis produced by root canal fillings than by any other mechanical irritant. In filling root canals we should be absolutely certain that the canal is aseptic. If there be any doubt as to this, the operation should be deferred. In a subsequent chapter the author will discuss in detail the technique of filling root canals; however it is well to mention here that care should be taken in filling all large canals so that the filling material may not be forced through the apex of the root; especially should we be careful in filling the canals of teeth after having treated an alveolar abscess. In these cases we must not expect the patient to flinch in filling the root, for there is no live tissue at the immediate end. The apex has been enlarged and it is very easy to force the filling material through into the space where the tissue has been destroyed. When granulation fills this space and the newly formed tissue comes in contact with the foreign material, the result will be a "lame tooth," which means pericemental trouble. A frequent cause of pericementitis is the presence of microorgan- isms, which have been introduced through the failure to establish and maintain sepsis in removing the pulp tissue; or pathogenic bacteria, poisonous ptomains and irritating gases that have escaped into the apical area from a putrescent root canal. This particular kind of pericementitis is known as septic pericementitis, and is closely associated with incipient abscess. The nature of the irritants and the treatment of the condition will be fully considered in a subsequent chapter. Therapeutics. — The first step in the treatment of ordinary peri- cementitis is to adopt the surgical principle of ascertaining the cause and removing or correcting it, if at all possible. In the earlier stages of pericemental inflammation, it is not always an easy matter to ascer- tain the true cause of the disturbance. For instance, in those cases following the removal of the pulp tissue, it is difficult to know whether the cause is the root filling, the medicine used in the treatment, or whether we failed to establish and maintain asepsis in performing the operation. The author is inclined to believe that it is more frequently the latter than most operators are willing to admit; for certain it is that the more nearly we approach absolute asepsis in these operations, the less pericemental trouble we will have. The teeth thus affected are extremely sore, and any remedy can be used in the treatment that will give immediate relief. This is what the patient most desires, and, too often it appears, it is that which the dentist fails to give. Both local and general remedies can be employed. General remedies are more valuable in the treatment of septic pericementitis. If they are 346 THE TREATMENT OF ORDINARY PERICEMENTITIS. used at all in treating ordinary pericementitis, they should be used only in cases where the patient is nervous and has lost considerable sleep. For immediate relief we must depend largely upon the local applica- tion of drugs and remedies. In those cases following the removal of the pulp by either the anesthetization or devitalization method, and where the canals have not been filled, the pain can be relieved almost instantly by the following method: Adjust the rubber dam. If it is necessary to use a clamp, it should be placed on the tooth posterior to the one affected. Sterilize the teeth included in the dam and re- move the dressing from the canals. Dehydrate the tooth structure with absolute alcohol. Then wrap cotton loosely around a smooth, sterile broach, dip in oil of cloves or eugenol, and carefully work in each canal. Remove the broach, leaving the cotton. Heat should now be applied to the remedy by means of a hot air instrument or a chip- blower until the cotton becomes dry. Repeat this process several times, after which the same remedy should be carefully sealed within the canal. In doing this, we not only get the benefit of the heat, which is valuable; but the eugenol, the constituent of cloves, is driven into the tooth structure, producing a profound anodyne effect upon the sensitive membrane. The author has succeeded in giving immediate relief by this method of treatment when many others have failed. Grinding the cusps of the tooth where it can be done without injury is advisable; a counterirritant can be applied to the gum and the patient dismissed for several days. It is scarcely necessary to instruct the patient to favor the tooth. In the treatment of pericementitis following the filling of the root, having every reason for believing that the canals were aseptic, one of the last things the author would suggest doing would be to attempt to remove the root filling. Usually this only serves to further aggravate the condition. These cases can best be treated by counterirritation and general remedies. By counterirritation is meant the application of an irritant to some normal part of the body for the purpose of influenc- ing favorably some other part, usually deep-seated, which is diseased. This irritant is generally applied to the gum over the affected tooth. Capsicum plasters, black mustard papers, cantharidal collodion, all official preparations, are valuable; or the following liniments, which are more generally used, give much relief: I^ — Menthol is, gr. xx Chloroformi, f. 3 j Tin cturae aeon iti, q. s ad, f . 5 j — M. — Dry the gum and apply freely over the af- fected tooth for several minutes. GENERAL CONSIDERATIONS. 347 E^ — Tincturae aconiti, f. 5 ij Tincturae iodi, Chloroformi, aa f . 3 j ■ M. Sig. — Make one -application to the gum as above. I^ — Liquoris iodi compositae, f. 5 j Sig. — Use as above. Inasmuch as tincture of aconite is an important ingredient in many liniments used in the local treatment of pericementitis and facial neu- ralgia, it is well to remember that the United States Pharmacopeia of 1900 reduced the strength of this preparation from 35 per cent to 10 per cent. Therefore the new tincture can be employed more freely in these cases without danger of poisoning. As a remedy to be applied by the patient at home, a split raisin, soaked in hot water, and on which is dusted red pepper, can be held on the gum over the affected tooth. A very efficacious remedy is to di- rect hot water with some force on the part, beginning with warm water and increasing the heat gradually until it is nearly boiling. This must be kept up until we get the full benefit of the heat and resolution pro- moted. Another good remedy to have the patient employ, is the hot foot bath. The value of this remedy, like the application of hot water to the gums, depends largely upon the manner in which it is done. A deep foot-bath tub should be used and the temperature of the water gradually increased until it is as hot as can be borne. This should be continued from twenty to thirty minutes. Frequently the pain can be relieved by spraying with ethyl chlorid the area over the offending tooth. There are many other drugs and remedies which can be employed in the local treatment of this condition. Those which have been men- tioned here the author has found valuable in his practice. It is far better to have a practical knowledge of a few remedies than a super- ficial knowledge of many. The general remedies to be administered in the treatment of ordinary pericementitis, if found necessary, will be discussed under the treatment of septic pericementitis and incipient abscess in a subsequent chapter. CHAFTER XXI. THE CHEMISTRY OF PULP DECOMPOSITION. BY J. P. BUCKLEY, PH.G., D. D. S. General Considerations. — The subject of pulp decomposition is one that has commanded the attention of many investigators in our pro- fession, and at the present time the conclusions as to the chemistry of the process are by no means uniform. While this fact is to be regretted, it must be remembered here that there are many difficulties presenting themselves to the student who attempts to study this complicated proc- ess from the chemical viewpoint, either for the purpose of outlining a rational treatment for the correction of the putrescent condition, or for the purpose of solving the knotty problems of the discoloration of tooth structure from this source. Until we comprehend more fully the nature of the chemical reactions taking place in the splitting up of the com- plex bodies of dead pulp tissue and have a more definite knowledge of the intermediate and end-products thus produced, the application of drugs and remedies for the correction of the putrescent condition and for the restoration of the color of the tooth structure can never be placed upon a rational basis, but must be empirical, as it has been in the past. This is not in accordance with the tendency of the present time. There is a strenuous effort being made in both medicine and dentistry, to rid the professions of much of the empiricism of the past and to place the treatment of all diseased conditions upon a rational basis. With this end in view the author desires in this chapter to direct the reader's attention to the chemistry of pulp decomposition. It is essential . in studying the chemistry of this process to first as- certain the chemical constituents of the original pulp tissue. So far as chemists have been able to determine, practically all of the elements are present in the pulp tissue and its vascular supply that are found in any other animal tissue. These elements are arranged in different compounds which make up the pulp tissue, the proportion of which varies from other tissues, and this, no doubt, accounts for the histologic difference between this and many of the other tissues of the body. However, from a general chemical examination of the pulp tissue we find it analogous, or nearly so, to all other animal tissue. This suggests 349 350 THE CHEMISTRY OF PULP DECOMPOSITION. at once the necessity for the student's familiarity with the general composition of animal tissue, which will now be considered. Chemical Composition of Animal Tissue. — There are at the present time about seventy-six elements known to chemistry; but of this num- ber less than seventeen unite, in varying proportions, to form the chem- ical basis of the animal body. In fact, six elements are about all with which we are concerned in the study of the decomposition of the pulp tissue. These elements are carbon, C; hydrogen, H; oxygen, O; nitrogen, N; sulphur, S; and iron, Fe. For convenience in study, the various substances found in animal tissue arc divided into two general classes, the classification being based upon the presence or absence of the element nitrogen, and are accord- ingly called nitrogenous and non-nitrogenous substances. Nitrogenous Substances. — We are taught by physiologists that nitrogenous organic bodies take the chief part in forming the solid tissues, and to an extent are also found in the fluids of the body. Pro- teid, or albuminous, substances are the principal nitrogenous com- pounds, and one or more enter as an essential part into the formation of all living tissue. The elements which constitute the proteid molar cule are carbon, hydrogen, oxygen, nitrogen and a small amount of sulphur. Iron and phosphorus are known to exist in the molecule of some proteid bodies. While some chemists have attempted to con- struct a formula for the molecule, none has been accepted as correct, the opinions of investigators being so varied. To the casual observer it may seem strange that a molecule consisting largely, as it does, of carbon, hydrogen, oxygen and nitrogen, should have these four simple elements so arranged as to bafHe chemists in their effort to construct a rational formula. But this difficulty is readily explained by the fact that of all the elements none differ more widely from each other in their physical and chemical properties than these four. Carbon is a solid substance which exists in nature in three forms: Charcoal, graphite, and diamond, and can scarcely be fused or volatilized. Hy- drogen, oxygen, and nitrogen are colorless gases which cannot be solidified by any known means and can be converted into liquids only with difficulty. The three gases also differ in their chemical activity. Hydrogen is combustible; oxygen will not burn, but will support com- bustion; while nitrogen is perfectly indifferent. Fortunately, too, for nature, in her effort to arrange these elements into a complex molecule, the valency of each differs. Hydrogen is univalent, oxygen bivalent, nitrogen trivalent, and carbon quadrivalent, generally considered. Carbon atoms have also, to a higher degree than the atoms of any other GENERAL CONSIDERATIONS. 35 1 element, the power of combining with each other by means of a portion of the affinity possessed by each atom, thereby increasing the possibil- ities of the formation of complex compounds. Thus many atoms of the same element occur in each molecule, which, together with the fact that one of the elements is that peculiar, undecided and indifferent element, nitrogen, aids materially in explaining the reason for the insta- bility of the proteid molecule, or the ease with which under certain conditions it is decomposed. In order that the reader may be able to follow a theory which the author will advance in a subsequent chapter on the discoloration prob- lem, it is well to remember here that the relative amount of nitrogen compared with sulphur found in the proteid molecule is 15 per cent of the former to 0.3 per cent of the latter. Non-nitrogenous Substances. — The non-nitrogenous substances con- sist of carbohydrates and jats. Several classes of carbohydrates are known to exist, all of which are much less complex than the proteid group; and the arrangement of the atoms in the molecule is much better imderstood. The carbohydrate molecule is composed of three ele- ments — carbon, hydrogen and oxygen. There are alw^ays six (or a multiple of six) atoms of carbon in the molecule, while the hydrogen and oxygen exist in the proportion to form water. These compounds readily undergo the process of fermentation. Human fats are principally mixtures of palmitin, C3Hs(Ci6H3iO)3- O3; stearin, C3H5(Ci8H,50),03; and a small amount of olein, C3HS- (C,8H330)303. As shown by the formula of these compounds, the molecules of each also consist of carbon, hydrogen and oxygen. The proportion of these elements varies in the different compounds. That fats are decomposed or saponified by alkalies, or ferment in an alkaline medium, should be remembered, both in the treatment and the bleach- ing of teeth. Thus we have every reason for believing that the pulp tissue, like nearly all living organic tissue, is composed of proteids, carbohydrates, and fats; and on this hypothesis the author will endeavor to ascertain the intermediate and end-products resulting from the decomposition of this tissue when death occurs. Before doing so, however, it may be well that the reader fully understand what is meant by the terms fer- mentation and putrefaction. These terms are applied to peculiar kinds of decomposition by which the molecules of certain organic substances are broken up into simpler compounds. The difference between the terms is that fermentation is applied to the decomposition of those substances which belong to the group of carbohydrates, while putre- 352 THE CHEMISTRY OF PULP DECOMPOSITION. faction is applied to the decomposition of those substances which prop- erly belong to the proteid group and are classified as nitrogenous substances. Pu^p Decomposition. — The decomposition of the pulp tissue is essentially an analytic process which takes place gradually. Con- ditions being favorable, the germs present first act upon the complex and unstable substances composing the original tissue, splitting them up into less complex compounds, many of which are capable of further analysis; and the process goes on until simple and well-known com- pounds are the result. For convenience in studying this subject the compounds resulting from this analytic process will be arbitrarily divided into two classes, intermediate and end-products; and it will be seen that it is largely the products of putrefaction rather than of fer- mentation with which we have to contend in the correction of the putrescent condition. Intermediate Products. — The intermediate products depend to an extent upon the character of the microorganisms in the tissue, but it is safe to say that certain ptomains and amido-acids are formed. (i) Ptomains. — Ptomains are nitrogenous compounds of organic origin, having the reaction and basic property of alkalies. By some authorities they are called animal alkaloids, to distinguish them from a similar group of organic bases known as vegetable alkaloids. Among the ptomains liable to be produced are putrescin, C4H,^Nj, cadaverin and neuridin, C^Hj^N^, the last two named being isomeric as shown by the formula. One of these ptomains, neuridin, is non- poisonous; therefore its presence is of little importance other than to know that it is a nitrogenous base from which ammonia, NH3, or derivations of ammonia, is evolved by further putrefaction. Still, according to Vaughan and Novy, while pure neuridin is non-poison- ous, it possesses a toxic property as long as it is contaminated with other poisonous products of putrefaction. This holds true for all non- poisonous bases. In so far as the correction of the putrescent condition is concerned, putrescin and cadaverin are perhaps the most important intermediate products known to be formed in the splitting up of the proteid molecule. Like neuridin, they are basic nitrogenous com- pounds, capable of undergoing further putrefaction, evolving ammonia or derivatives; but unlike this compound, while they were at first re- garded as physiologically inactive, both of these bases have been proved by Scheurlen, Grawitz and others to be capable of producing inflamma- tion and suppuration. Therefore if by instrumentation or other- GENERAL CONSIDERATIONS. 353 wise they are forced through the apices of the roots, septic pericemen- titis or perhaps an acute alveolar abscess will result. (2) Amido-acids. — Amido-acids are acids in which hydrogen has been replaced by the univalent radical, NH^. Among the amido- acids formed in pulp decomposition, in all probability, are tyrosin, C6H40HC,H3(NHJCO,H, and leucin, CsH.oNH.CO.H. These substances, wherever found, have practically the same physiologic properties and pathologic significance. They occur in the intestine during the digestion of proteids, and leucin is found in almost every cell of the animal body.* Pathologically, they are found in ather- omatous cysts, in pus, abscesses, etc., as well as in a putrescent root canal. It is well to remember here that these intermediate products are also nitrogenous compounds from which ammonia, or derivatives of ammonia, is evolved by further putrefaction, and that jats are one of the end-products. End-products. — The chief end-products of pulp decomposition, as has been known for a long time, are water, H^O; carbon dioxid, COj; acetic acid, HC^H^O^; ammonia, NH3; hydrogen sulphid, H^S; and a semi-putrid substance consisting largely of fats, depending upon the extent to which the putrefactive process has progressed. Simultaneously with the decomposition of the pulp tissue proper, the dentinal fibrillse are broken up, as is also the hemoglobin and other constituents of the blood; and the tubuli as well as the pulp chamber and root canals are filled with the intermediate and end-products of the decomposition. The principal gases generated by the putrefaction of the proteid substances, the main constituent of the original pulp tissue, are ammo- nia and hydrogen sulphid. Now, it is interesting and important to know which of these two gases is evolved in the greater quantity. This is easily estimated when we recall the relative amount of nitrogen and sulphur found in the proteid molecule. As previously stated, there is approximately 15 per cent of the nitrogen to 0.3 per cent of sulphur. Hence, ammonia is evolved in the greater quantity. It is quite evident, then, that hydrogen sulphid is not generated in a putrescent root canal in such quantities as has been so generally supposed; yet this com- pound is a constant end-product and is important, because it is an acid gas, with a disagreeable odor, having local irritating properties; and also because of the part it plays in the discoloration of the tooth struc- ture. The author desires to state here, however, that while he realizes hydrogen sulphid is an active chemical agent, in his opinion it has been ♦Simon's "Manual of Chemistry." 23 354 THE CHEMISTRY OF PULP DECOMPOSITION greatly over-estimated in the r61e it assumes in the discoloration of teeth from pulp decomposition as will be shown in a subsequent chaf)ter. In our study thus far of the chemistry of the complicated process of pulp decomposition, we have learned something of the nature of the intermediate and end-products resulting therefrom, and now it is possible for us to select, with some intelligence, drugs and remedies which will not only destroy bacteria, but will also act chemically upon these noxious products, converting them into non-infectious and non- toxic compounds. CHAPTER XXII. THE TREATMENT OF PUTRESCENT PULPS— ACUTE AND CHRONIC ALVEOLAR ABSCESS, WITH COM- PLICATIONS; AND THE FILLING OF ROOT CANALS. BY J. P. BUCKLEY, PH.G., D. D. S. General Considerations. — ^The treatment of putrescent pulps and their sequelae in the past, has, to a great extent, been purely empirical. The reason for this can be found in the apparent lack of interest which generally has been shown in the chemistry of pulp decomposition. A knowledge of the changes wrought in the splitting up of the complex bodies of the dental pulp by microorganisms is of vital interest to every practicing dentist; and every student should therefore familiar- ize himself with this important subject. The only method by which drugs and remedies can be scientifically applied to the treatment of the conditions under consideration is to have a definite knowledge of the intermediate and end-products resulting from the putrefactive process as outlined in the preceding chapter. Every practitioner of dentistry knew from sad, past experience that in the process of pulp decomposition, some kind of mephitic gases were evolved W'hich if confined would produce severe pathologic disturbances; but just what the gases were and how the unfavorable conditions were brought about we were left to conjecture. From our study of the chemistry of pulp decomposition we have every reason for believing thai the main gases produced are ammonia and hydrogen sulphid. When these gases are generated and cannot readily escape through a cavity, pressure is produced, thereby forcing microorganisms and their poisonous ptomains through the apices of the roots into the surrounding tissue from which infection, septic pericementitis and in many instances an alveolar abscess result. There has been much discussion in the dental literature of the past in regard to the penetrating or non-penetrating power of coagulating agents in putrescent root canals. It is true, as claimed by some authorities, that such drugs as phenol, creosote, solutions of zinc chlorid, etc., are contraindicated in the treatment of putrescent pulps, but not 355 356 THE TREATMENT OF PUTRESCENT PULPS. because they possess the coagulating property; for when the dental pulp is undergoing or has undergone the process of decomposition, the proteid constituents or coagulable substances have lost their for raer identity, and new compounds with entirely different properties have been formed. In selecting drugs to be used in the treatment of this condition, the author will therefore eliminate the question of coag- ulation and will select drugs, which, if properly used, will unite chemic- ally with the intermediate and end-products of decomposition, con- verting them into odorless and non-infectious compounds, as well as destroy germ life. In this connection it should be remembered that the putrescent condition has been brought about through the agency of microorganisms by a gradual analytic process, and among the products formed which must be considered in the treatment are hydrogeji sulphid, the poisonous plomains (putrescin and cadaverin), and ammonia or derivatives, the latter gas being evolved from the further putrefaction of the last named compounds, or compounds of similar composition. It is well to remember also that fats or fatty acids are a class of end-products resulting from the putrefaction of proteid substances. The main gases formed, then, are ammonia and hydrogen sulphid. Now it will be necessary to dispose of these gases in order to hermetic- ally seal the cavity, an object the accomplishment of which is much desired in the treatment of these cases; for by so doing we prevent the oral fluids from contaminating the medicine within the tooth, the med- icine from escaping into the patient's mouth, and the tooth from changing color during the time of treatment. It has been known for some time that Jormaldehyd (CHjO), a gas which occurs in commerce in a thirty-seven per cent aqueous solution and which solution is recognized by the United States Pharmacopeia of 1900 under the name of liquor formaldehyd, or formalin, will unite with ammonia, producing urotropin, a solid, as 6CH2O+4NH3 = (CH,)5N,+6H,0. Formaldehyd unites also with hydrogen sulphid, forming, in the author's opinion, methyl alcohol, a liquid, and sulphur, a solid, as 2CH,0 + 2H S = 2CH30H-hS,. It is stated on good authority that this same gas, formaldehyd, unites with basic ptomains, forming inodorous compounds. By the use of formaldehyd, then the irritating gases and poisonous liquids (largely ptomains) can be changed chemically into non-irritating and non-poisonous liquids and solids. The official solution of formaldehyd, however, is too irritating for general use; therefore, inasmuch as fats GENERAL . CONSIDERATIONS. 357 result from pulp decomposition and are present as such in a putres- cent root canal, the author selected cresol as an agent with which to dilute the official solution and thereby modify the irritating action of formaldehyd. Cresol is now also recognized by the United States Pharmacopeia of 1900 under this name. Formerly the product was commercially called tricresol. This agent has a tendency to darken when exposed to light. It is recommended that a clear solution be obtained and then kept in an amber colored bottle. Liquor formaldehyd can be diluted with such other agents as phenol, or creosote, if, in the latter instance, a small amount of alcohol is added to clear the solution. Cresol, however, is recommended for four principal reasons: 1. It is miscible with the liquor formaldehyd in all proportions, thus making, without the addition of alcohol, a good pharmacal product from which formaldehyd gas is constantly generated. 2. It is a good disinfectant, much more powerful than phenol. 3. It possesses an anodyne property which modifies the irritating action of formaldehyd. 4. It acts chemically upon the fatty compounds thereby disposing to advantage of these substances. Treatment. — In the successful treatment of the conditions under consideration there are three important factors which must be ac- complished : 1. Establish asepsis. 2. Prevent recurring sepsis. 3. Preserve or restore the color of the tooth. I. Putrescent Pulps. — In calling the attention of the reader to a method of treating this condition, which has proved very successful in the author's practice, I desire to emphasize the necessity for ob- serving the details of the method. Our first duty here, as in all treat- ment cases, is to make a correct diagnosis, after which the rubber dam should be adjusted in every case where it is possible to do so, and all the teeth included, sterilized. For this purpose either a ten per cent solution of formaldehyd to which a small amount of borax has been added, or a 1-500 solution of mercury bichlorid in cinnamon water can be used. After using one of these solutions the teeth are bathed in alcohol, when, with a suitable round bur, the pulp chamber is freely opened, exposing all of the canals, but making no attempt to remove the contents therein at this sitting. Now, on a small pledget of cotton the following remedy is placed in the pulp chamber and over the mouth of each canal. 358 THE TREATMENT OF PUTRESCENT PULPS. Original Formula. I^ — Cresolis, Liquoris formaldehydi, aa f3j — M. Sig. — Use as directed. For convenience this remedy will be called jormocresol. It is always best to seal the cavity with a quick-setting cement, for the remedy should be hermetically sealed and pressure must he avoided. To prevent the cement from filling the entire cavity and also to facili- tate its subsequent removal, metallic or paper discs or even cotton can be placed over the remedy, filling most of the cavity, when only a veneer of cement is necessary to hermetically seal it. This dressing can re- main until you wish to have the patient return for a subsequent sitting. The author prefers to leave it about two or three days. However, it can be safely changed the following day, and no harm follow if it remains a week or more. At the second sitting, the rubber dam should be adjusted, the teeth included sterilized, and the dressing removed, after which the canals should be mechanically cleaned with a proper broach, exercising the same judgment here in the selection of the broach as was emphasized in a previous chapter. If there be any odor in the canals characteristic of putrescence, or if effervescence is produced by testing with a solution of hydrogen dioxid, the canals should be dehydrated with alcohol and warm air as thoroughly as possible and formocresol again placed on cotton, this time loosely in each canal, and the cavity hermetically sealed. In those cases, where, at the second sitting, there is no evidence of putrescence, which will be found to be the condition generally if the first treatment is properly employed, the original formula can be modified and used. It is not necessary or advisable, however, to keep a modified formula prepared. It can readily be made at the time by taking two minims of the original formula on a clean watch crystal, and adding to this one or two minims of cresol as thought best by the operator at the time. This dressing should remain for at least three days, by which time the remedy will have sterilized the entire tubular structure of the dentin, thus establishing asepsis. All that is necessary now to prevent recurring sepsis is to thoroughly fill the canals. This remedy will not discolor tooth structure and the fact that it not only can but should be hermetically sealed in the cavity, will prevent discoloration by the ingress of the fluids of the mouth. In case the color of the tooth crown was lost before undertaking the treatment and being desirous of preserving the tooth by an inlay or filling, the color can be restored by one or two applications of sodium dioxid, NajO,. GENERAL CONSIDERATIONS. 359 or by sealing a 25 per cent ethereal solution of hydrogen dioxid (pyrozone) in the cavity for twenty-four or forty-eight hours. The use of sodium dioxid will be explained in a subsequent chapter on bleaching teeth. Complications. — i. Badly Decayed Root. — This formocresol is very destructive to the soft tissues of the mouth, therefore the im- protance of always adjusting the rubber dam. If this cannot be done on account of a badly decayed root, it is suggested that care be taken in seahng the remedy in the cavity at the first sitting, and, in placing the cement, the original outline of the root can be approximated. After the cement has set, a band or matrix of gold or German silver can be fitted to and cemented on the root. In treating the case where there is a tooth posterior, it is best to place the clamp on this tooth and gently stretch the rubber over the band and thereby avoid loosening it. 2. Pulp Partially Alive. — In those cases where the pulp tissue is putrescent in one or more canals of a multirooted tooth and alive in the other one or two canals, as the case may be, we will find much satisfaction in using the formocresol remedy. These are exceptional cases and it is difficult to know whether this condition exists until the second sitting. If there be much vitality in the live pulp tissue, the formaldehyd in the remedy will doubtless make the tooth ache, but after we know the conditions our method of procedure is simple and the results will be certain. A small pledget of cotton dipped in the remedy can be gently placed over the mouth of the canals which con- tain putrescent material, and a thin quick-setting cement flowed over the cotton. After the cement has set the live pulp tissue in the remain- ing canals can be anesthetized or devitalized as the operator deems best at the time. Formerly these were difficult cases to treat, but with a remedy which can be hermetically sealed in a putrescent root canal, the procedure is materially simplified. The author realizes that the method of treating putrescent pulps, here given, is a radical departure from those generally advocated ; and, like myself at first, some of my experienced readers may hesitate to hermetically seal a cavity in a tooth which contains a putrescent pulp. The reason this could not be done in the past by the methods in vogue, is that drugs, in most instances, were selected and used solely because of their ability to inhibit the growth or destroy the vitality of micro- organisms. The fact that there were other things, such as irritating gases, and poisonous ptomains, found in the canal and tubular structure of the dentin, and also the further fact that it was as necessary to dispose of these substances as it was to destroy germ life, was not given the 360 THE TREATMENT OF PUTRESCENT PULPS. significance this phase of the subject merited. The treatment which is here outlined is along rational lines, for the remedy chemically converts the noxious intermediate and end-products of pulp decom- position into substances which themselves possess antiseptic and dis- infectant properties. II. Acute Alveolar Abscess. — The treatment of septic perice- mentitis and acute alveolar abscess, as was intimated in the chapter on The Treatment of Pericementitis, is so nearly identical that they will be discussed here conjointly. In those cases where the patient did not present for treatment until the confined gases had escaped through the end of the root, carrying the microorganisms and poisonous ptomains into the surrounding tissue, it is our duty to try to aid nature in aborting an abscess. It is in these cases that good ji^dg- ment must be exercised, and extreme care taken. There is no condition which we are called upon to treat wherein a practical knowledge of path- ology and therapeutics will serve us better than in this particular case. Frequently patients delay coming to the dentist until the infection has progressed to a point where all remedies will fail in aborting an abscess ; but in many instances this result may be prevented by the proper use of drugs. The local treatment here is exactly the same as above for an ordinary putrescent pulp; for you never have a case of septic pericementitis or incipient abscess unless the pulp is dead and has undergone, partially at least, the process of decomposition. How- ever, if the tooth is extremely sore, as is usually the case, the patient need not be subjected at this sitting to the annoyance of adjusting the rubber dam. Keep the tooth just as dry as possible, open into the pulp chamber, holding the tooth by some means while drilling, so that the jarring will not further irritate the condition; then carefully seal in the formocresol remedy with cement; after which our attention, if necessary, should be given to the treatment of the infected peri- cemental membrane. In order to control the infection, and at the same time aid nature in readjusting the abnormal condition, it is not only our privilege, but it is our duty in these severe cases to administer internal drugs. Here alterative drugs are indicated. The great rep- resentative of the alterative class is potassium iodid, which can be given in the following prescription: I^ — Potassii iodidi, 3 jss Syrupi sarsaparillse comp., f5 iij — M. Sig. — Take a teaspoonful in water after meals. Ordinarily the directions would be as given, to have the patient take a teaspoonful three times a day after meals; but in these cases of GENERAL CONSIDERATIONS. 36 1 septic pericementitis or incipient abscess it is best to direct the patient to take a teaspoonful every two hours until three or four doses are taken, and then follow the directions written on the label. It is well also to avoid the accumulation of blood in the part. To prevent this, saline cathartics are indicated — one that can be given is the official solution of magnesium citrate, owing to the facility with which it can be taken and its acceptability to the stomach, a prescription for which follows : I^ — Liquoris magnesii citratis, f5 xij Sig. — Take one half at once and the other half in two hours, if necessary. An eflfervescent magnesium citrate is now prepared by pharmaceu- tical houses, and this here will be found useful. Magnesium sulphate (Epsom salts) is also an excellent remedy to be used for this latter purpose. The patient can be directed to take a teaspoonful dis- solved in a wine-glassful of warm water, having a glass of cold drink- ing water at hand to drink at once after taking the strong salt solution. The cold water removes at once the bitter and unpleasant taste of the salt. A very good remedy to have the patient employ at home is the hot foot bath as explained in the chapter on The Treatment of Pericementitis. In malarial regions and in the spring of the year in many localities, the salts of quinin can be given, with beneficial results. The salt which the author prefers giving, if indicated in the conditions under consideration, is quinin bisulphate. Nearly all pharmacies have the salts of quinin put up in the form of pills. While these pills may be given it is much better to write a prescription for capsules. The gelatin capsule is soon dissolved in the stomach; thus we obtain the action of the drug more rapidly than when given in the dry, hard, pilular form. The following prescription can be written for the drug in two grain doses: I^ — Quininae bisulphatis, gr. xxiv Ft. capsulse No. 12. Sig. — Take one capsule every hour until the effect become noticeable. Quinin acts differently upon different individuals. Most adult pa- tients know the effect of this drug upon their system and therefore will be able to aid the dentist in determining the amount to be taken in a given case. One of the most prominent symptoms with which we have to contend here is pain. In most cases the pain will subside soon after the local treatment; however, it is necessary occasionally, where the 362 THE TREATMENT OF PUTRESCENT PULPS. patient is nervous and has lost considerable sleep, to administer drugs which act upon the central nervous system, thereby controlling the pain. There are several drugs which if properly given will pro- duce the desired efifect. The United States Pharmacopeia of 1900 recognizes a compound powder of acetanilid which is recommended and can be prescribed as follows: ^ — Pulveris acetanilidi comp. gr. xij Ft. chartulae No. 2. Sig. — Take one powder at once and the other in two hours, if not relieved. Another very useful prescription for acetanilid is one suggested by the late Dr. A. W. Harlan. I^ — Acetanilidi, gr. viij Syrupi simplex, f 5 ss Spiritub frumenti, q. s. ad, £5 iij — M Sig. — Take one-half at once and the remainder in two hours, if not relieved. Dr. J. E. Keefe, of Chicago, suggests the following remedy by which he claims instantaneous and often permanent relief can be obtained: PJ — Alcohohs, Aquae, aa fg j— M. Sig. — Use as directed. This remedy is best administered in the form of a spray, using a watch case atomizer for liquids, forcing the spray well back into the nostril on whichever side the affected tooth is located. The application can be repeated as often as is necessary without any ill effects. In case an atomizer of any kind is not at hand, about fifteen minims of the remedy can be placed far back in the nostril with a suitable syringe. The author does not wish to be understood as suggesting these various internal remedies in all cases of acute abscess. No therapeu- tist can tell exactly what internal drugs he would suggest without seeing the case and knowing the history; for there are many circum- stances and conditions which modify the effect of drugs. Every rem- edy here mentioned, however, will be found useful in certain cases. III. Chronic Alveolar Abscess. — There are two varieties of chronic alveolar abscesses — those without an external opening, ex- cept perhaps through a cavity in the offending tooth, and those which are discharging through a sinus. In these cases the decomposition of the pulp tissue is complete; the intermediate products (ptomains and amido-acids) have largely been broken up, and pus has been formed from the tissue and fluids surrounding the ends of the roots GENERAL CONSIDERATIONS. 363 I. Abscess without Sinus. — In treating that variety of alveolar abscess which is without an external opening, our method of proced- ure is somewhat different. The tooth should be located; the rub- ber dam adjusted, and the teeth sterilized as before; then the pulp chamber is opened with a suitable round bur. Usually the pus flows freely, in which case it is permitted to do so, pressure being made on the tissue immediately over the end of the root. It should be our effort to mechanically evacuate as much pus at each sitting as is pos- sible. This being done, we have no necessity for using formaldehyd in the same strength solution as in those cases where the pulp chambers, root canals, and tubuli are filled with the intermediate and end-products. The modified formocresol remedy will be useful here. The canals should be dried with alcohol as thoroughly as possible and the remedy on cotton hermetically sealed in each canal. It is, however, at this sitting, impossible to get the canals dry, and it is unnecessary to have them so, for the remedy will penetrate where moisture is present. This is an advantage over most remedies suggested for this purpose. In those cases where there is a copious flow of pus at the first sitting, the original formula can be used, and the dressing should be changed every day until it can be removed without the pus flowing from the canals. When pus is forming rapidly at the end of the roots, the dress- ing soon becomes dissipated, the remedy is neutralized, and it is a loss of time to leave it in the canals more than twenty-four hours. Unless there be some complication, the pus formation should be checked in one or two treatments; at which time the modified formocresol remedy can again be used. It is now possible to change the dressing too often. The formation of pus has been checked, and the tooth should not be disturbed for at least one w^eek or ten days, in order to give nature a chance to effect a cure. If at the end of this time there is no evidence of pus and the case gives a favorable history, the canals can be filled. Should there, however, be a slight odor although the tooth has not caused any trouble, we are not justified in filling the root. In these cases phenol compound can be substituted for formo- cresol and used with gratifying results. It should be remembered that the value of formaldehyd in any remedy to be used in the treatment of these conditions depends upon the power this agent has of uniting chemically with hydrogen sulphid, ammonia and poisonous ptomains. When these substances are not present, formaldehyd, especially in this strength solution, is contraindicated. This precaution is mentioned here because formaldehyd is an irritating gas and any remedy contain- ing it should be modified according to the conditions as found. 364 THE TREATMENT OF PUTRESCENT PULPS. Quite frequently in these alveolar abscess cases, after the formation of pus has been checked we have a weeping of serum from the canals. An excellent remedy to use in this case is eucalyptol to which thymo! has been added in the following proportion: I^ — Thymolis, gr. x Eucalyptolis, f5j — M. Sig. — Dry the canal as much as possible and hermetically seal in the remedy. If this remedy fails to check the secretion and the fluid is serum not pus, no hesitancy need be felt as to filling the root, although the canals cannot be dried. Occasionally we find a chronic alveolar abscess of this variety where it is almost impossible to check the formation of pus by apply- ing drugs to the canals of the teeth. In such cases the radiograph will aid materially in determining the area involved. In those canals where the pus continues to flow freely when the dressing is removed at the third or fourth sitting, some complication can be expected. It is necessary then to force some stimulating agent through the apices of the roots, after the pus has been mechanically evacuated. The stimulating agent which the author uses almost invariably is a fifty per cent solu- tion of phenolsulphonic acid. In resorting to this means of bring- ing about a more acute condition, I desire to emphasize the necessity of first evacuating the pus as completely as possible before using the remedy, after which the agent should be gently forced through the apices and the modified formocresol remedy sealed in the canal. It will be found that one or two treatments will usually check the for- mation of pus, after which the case can be treated as an ordinary- abscess of this kind. In case this method fails to effect a cure, however, it will be necessary to surgically establish an opening through the over- lying process and soft tissue and treat as for an ordinary discharging abscess — which treatment will now be considered. 2. Abscess with Sinus. — In those cases where the pus is dis- charging into the mouth through a sinus, our first duty is to locate the offending tooth. This is generally a simple matter for the reason that the sinus usually opens immediately over the tooth from which it comes. The pus in making its exit, however, follows the line of least resistance, and in some cases the condition of the process is such that the pus burrows forward or backward, and opens through the gum at a point several teeth removed from the one which is causing the trouble. These are the cases that are difficult to diagnose, especially where the abscess has been discharging for some time, when there is not much tenderness in any special tooth, and where there are several GENERAL CONSIDERATIONS. 365 pulpless teeth on this side of the mouth. Sometimes two teeth con- taining putrescent pulps have a common sinus. In this case it would be impossible to heal the tract by treating only one of the teeth. The radiograph is the best means at our command for determining the tooth or teeth involved. In the absence of the X-ray the silver probe will be found valuable. By gently working the probe forward or backward the sinus can be explored and the offending tooth or teeth located without drilUng into innocent teeth — a discouraging procedure to both patient and dentist. The tooth being located, all that is necessary to effect a cure — there being no complication — is to force some bland solution through the root canal and sinus, thus being certain it is well established; cauterize the tract, hermetically seal in the canal or canals the same agent used for this latter purpose or the modified formocresol remedy, and, at the subsequent sitting, the case giving a favorable history, fill the root. Establishing Sinus. — If the abscess is not discharging, and it is well in those cases where it is discharging, before adjusting the rubber dam, to enlarge the mouth of the sinus with a lancet or bistoury. By dipping the lancet in phenol, this may be accomplished with very little pain to the patient. After this is done the rubber dam should be adjusted and the canals freely exposed. Now that the infection is past the end of the root, we need not hesitate to mechanically clean the canal at this sitting. The canals being clean we are ready to establish the sinus. To do this we need a bland solution and a good hypodermic syringe with a long straight needle for anterior and a long curved needle, for posterior teeth. There is an advantage in having a long needle, for the nearer the point is to the apex of the root, the less packing and force is required to send the solution through the sinus. Any bland solution can be used for this purpose. The author suggests peppermint water to which two minims of phenol has been added to the fluid ounce. Physiologic salt solution is also good. A piece of unvulcanized rubber of the proper size should be selected, softened in the flame, and a hole made in the center through which the needle is placed and inserted into the canal. The rubber should now be tightly packed around the needle and held on either side with flat nose pliers, when pressure can be made on the piston of the syringe and the solution forced through the sinus. This should be repeated several times, care being taken not to break the needle in the canal. If convenient one comer of the dam can be raised, exposing the mouth of the sinus to view. There are two objects in forcing a bland solution through the sinus: one is to be certain that it is open, and the other is to mechanically wash out the pus. Whenever pus can be mechanically 366 THE TREATMENT OF PUTRESCENT PULPS. removed, it is always better to dispose of it by this means rather than to do so by the use of some chemical agent. It is common practice after the sinus is established to use a solution of hydrogen dioxid. This is often a dangerous procedure and always unnecessary if the first solution has been used in sufiScient quantity. For cauterizing the sinus in simple cases ninety-five per cent phenol has been largely employed. An ex- cellent preparation to use for this purpose is phenol compound. With the sinus well established, it is never necessary to place either of these solutions in a hypodermic syringe. The author knows of several in- stances where this has been tried with disastrous results. The remedy can be applied to the canals on cotton, when, with unvulcanized rub- ber and a suitable instrument, it can be forced through the sinus. Alcohol is a positive antidote for phenol; the alcohol bottle should therefore be in a convenient place so that the remedy used in the canal can be neutralized at once when it appears at the mouth of the sinus. If this has been well done, it matters little what drug or remedy is sealed in the canal. The phenol compound or the modified formo- cresol solution will give excellent results if hermetically sealed in the canals for about one week. In cases of long standing when we can reasonably suspect a roughening of the end of the root or process through which the pus has been discharging, it is good practice to use, as the cauterizing agent, a fifty per cent solution of phenolsulphonic acid, and in stubborn cases the pure acid can be employed. The author does not believe in delaying the root filling long after the sinus has been cauterized in uncomplicated cases; for by filling the root as soon as we are certain that the sinus is healing, we avoid a weeping condition, which usually exists and which is annoying when this part of the treatment is de- layed for one month or six weeks as advocated by some writers. In these cases where the first treatment has been thorough, and the case gives a favorable history, the root should be filled at the second, or, at most, at the third sitting. If the case does not yield to the above treat- ment, some complication may be expected. It is sometimes difficult to estabhsh the sinus, especially on molar teeth. In all such cases where there is no complication, the case can be nicely treated with the formocresol solution as outlined under treatment of abscess without sinus. Before referring to complicated cases the treatment of putrescent pulps and abscesses associated with deciduous teeth will be considered. Treatment of Putrescent Pulps and Abscesses in Deciduous Teeth. — In treating the conditions under consideration, in the mouths of children, it is necessary in most cases to modify our usual method GENERAL CONSIDERATIONS. 367 of treatment. Our first duty here is to gain the confidence of the child. If the abscess is associated with a deciduous molar which we would desire to save for at least a year or two, it can be treated nicely in the following manner: After gaining the confidence of the little patient the mouth can be rinsed with an antiseptic solution — one which has a pleasant taste. Then open into the pulp chamber and place a pledget of cotton in the opening. Now mix on one end of the ce- ment slab thymolized calcium phosphate and the formocresol remedy, making a stiff paste. On the other end of the slab have a quick set- ting cement ready to mix. Again rinse the patient's mouth and, keeping the cavity as dry as possible, gently pack the paste into the pulp chamber and flow the cement over it, filling the cavity. If deemed advisable, the cavity can be prepared in the cement and filled with amalgam. It is remarkable how rapidly these abscesses will heal and remain quiet when treated in this manner, provided, of course, there be no caries or necrosis of bone. Complications. — There are several complications of chronic al- veolar abscess of both varieties, with and without a sinus, where it is necessary to modify or change the general method of treatment to meet the conditions as they exist. For instance, in the case of an abscess without a sinus where we can reasonably suspect, and where the indications point to a roughening of the end of the root, we ought not to expect to cure the case by simply sealing remedies within the canals of the tooth. If we do, we are expecting too much of drugs. Again, in a case of an abscess with a sinus where the pus has been dis- charging for several months, with the not unusual result that the end of the root or process through which the pus has discharged has become roughened, we should not expect to effect a cure by forcing phenol or phenol compound through the sinus; because such agents as these have no action whatever on the bony structures. I. Denuded End 0} Root. — One complication we may expect to find in abscesses of long standing, especially in the variety without a sinus, is where a large area of tissue in the apical space has been ab- sorbed or broken down, denuding the end of the root and the denuded portion projecting into the absorbed area. It is possible, in these cases, to make pressure over the end of the root and mechanically evacuate all of the pus above the apices; but we cannot expect by this means to evacuate the pus below and surrounding the end of the root projecting into the space. In this case we must do one of two things: Force some stimulating agent through the end of the root into the infected area, to create a more acute condition, or surgically 368 THE TREATMENT OF PUTRESCENT PULPS. establish a sinus through the overlying process and soft tissue and treat as an ordinary discharging abscess. While the author does not hesitate to adopt the latter method if necessary to effect a cure, it will be found that the use of a stimulating agent will generally suffice in these cases. The agents recommended are a fifty per cent solution of phenolsulphonic acid, or a fifteen per cent solution of trichloracetic acid. In using either of these solutions the pus should first be evac- uated as much as is possible; then the solution selected can be placed in the canal and gently forced through the apices and the modified formocresol solution sealed in the canal. One or two treatments will usually be sufficient to check the pus formation, when the case can be treated in the ordinary manner. 2. Resorted Root. — ^Another complication of both varieties of chronic alveolar abscess is where the pus has stood in contact with the end of the root sufficiently long to cause resorption, leaving a roughened end which irritates the tissue and prevents healing. Some- times, also, the process through which the pus has burrowed is left with sharp edges. In all such complications the "acid treatment" is especially indicated. These cases generally yield nicely to the treat- ment if phenolsulphonic acid is used as the agent with which to cau- terize the sinus. 3. Eficystmeni of Root. — A difficult complication to treat is where an abscess occurs on a root, the end of which has become encysted from deposits, excementosis or other causes. In order to effect a cure in these cases, it is necessary to establish a sinus and remove the de- posits, excise the root-end, or extract the tooth. The method of excis- ing the root-end will be discussed later. 4. Involving Vault. — Still another complication often difficult to cure is where the pus has worked its way through the lingual plate of bone and involves the vault of the mouth. The dense fibrous tissue covering the vault is very tough and the pus often separates the perios- teum from a considerable area of bone before ultimately discharging into the mouth. Generally a lancet is required to evacuate the pus. In treating these conditions it is essential to explore the affected area, using a sharp steel instrument in order to determine whether there is caries or necrosis. Unles" too much bone is involved the case can be successfully treated by first making a liberal opening with a sharp bistoury and, if necessary, breaking down the sharp edges of bone, through which the pus has burrowed, with a round bur having a long shank, after which the sinus should be established in the usual manner, using a considerable quantity of the bland solution. Now dry the GENERAL CONSIDERATIONS. 369 canal and force through the sinus full strength phenolsulphonic acid. Sometimes it is advisable to place a piece of blotting paper soaked in liquid petroleum over the lingual opening when forcing the acid through. This causes the agent to spread and come in contact with the entire area involved. Alcohol and the oils will neutralize any excess of the phenolsulphonic acid that may get on the other tissues of the mouth. This treatment should be repeated as often as the case demands. When there is no evidence of pus and the case has healed sufficiently so that there is only a watery discharge the root can be filled. 5. Secondary Abscess Pocket. — Occasionally we find an abscess of the discharging variety which does not yield to our general treat- ment, yet we are reasonably certain that none of the complications so far mentioned are present. In these cases we can suspect a secon- dary abscess pocket. This is especially true where the sinus opened into the mouth several teeth removed from the affected tooth. This pocket can usually be discovered by the aid of a small silver probe. The treatment is simple — all that is necessary is to open the pocket, wash it out first with a bland solution, then inject fifty per cent phenol- sulphonic acid. In using phenolsulphonic acid in such cases it cannot be injected through the tooth, therefore it is necessary to use a syringe — a glass syringe with an asbestos-packed plunger and a gold or a plat- inum needle should be used. 6. Involving Antrum. — The pus in making its exit follows the line of least resistance, and sometimes it is easier to work its way through the floor of the antrum than through the labial or lingual plate of bone. The treatment of this complication will not be dis- cussed here; but in this connection it is well to remember that so good an authority as Kyle, viewing the question from the nasal side, finds that fully fifty per cent of antral diseases are of dental origin. Excision of Root-end. — In all complicated abscesses which will not yield to the treatment outlined above, we can often save the root by excising its end. This should be done only as a last resort and then under the most aseptic measures. The hands of the operator, as well as all instruments used, should be thoroughly sterilized. Before operating, the root should be filled and a thorough exploration made that the amount of process and root involved may be noted. A local anesthetic injected deeply should be employed and an incision should be made. If only one tooth is involved the author prefers following the general method of Dr. M. I. Shamberg, of New York. The incision is made immediately over and parallel with the affected root. With a periosteotome the tissues are deflected on either side of the incision 24 37© THE TREATMENT OF PUTRESCENT PULPS. and held back by the author's tissue retractor. We now have the root- end exposed to view, when it can be excised or burred off as is indicated. After removing the excised end, the root remaining should be smoothed with a round bur and the area thoroughly curetted, removing any necrosed process which may be present. The wound should now be washed with an antiseptic solution and packed with sterile gauze. The patient should be instructed to keep the mouth as clean as possible and the packing should be changed every two days until granulation begins to fill the space. For a more detailed description of the surgery of chronic alveolar abscess see the author's work on Dental Therapeutics. Whenever the operator is in doubt as to the best means of treating complicated alveolar abscesses, he should never hesitate to consult with a practitioner who has had more experience in treating these cases. Such a course cannot be construed as a lack of knowledge, but is evidence of conservatism and progress. Pericemental Abscess. — All of the alveolar abscesses which we have discussed thus far in this chapter have been the result of an infection in the apical area, the infection being due to pathogenic bacteria, poisonous ptomains and irritating gases, which have escaped from a putrescent root canal. There is, however, an abscess that occurs in the alveolar region about the roots of teeth, not caused from the source mentioned. This particular kind of abscess occurs in connection with live teeth; not necessarily so, however. There is a progressive breaking down of the pericemental membrane and in dental literature it is called a pericemental abscess. The cause of this particular kind of abscess is rather vague; but it is generally supposed to be due to some traumatic injury. It frequently occurs on the labial surface of the roots of the anterior teeth involving most of this surface. They have also been known to occur between the roots of molar teeth, es- pecially the upper molars. While a pericemental abscess is often associated with pyorrhea alveolaris, care should be exercised, in mak- ing the diagnosis, not to get this condition confused with the latter disease. Treatment. — ^For convenience in outlining our treatment for a pericemental abscess, the condition may be classified as acute and chronic. As a rule there is very little pain associated with either variety of pericemental abscess. In the acute form, which, as such, is extremely difficult to diagnose, the patient will complain of " some- thing being wrong with a particular tooth." About all that can be done therapeutically with the acute form is to pacify the patient as best we can until the acute abscess develops into the chronic variety GENERAL CONSIDERATIONS. 371 when pus is formed and discharges usually at the gum margin, and thus the diagnosis is more easily made. If the abscess occurs on the anterior teeth where the area involved can be curetted and cauterized it will generally yield to the treatment; but the treatment of a chronic pericemental abscess on molar teeth is at best a discouraging procedure and practically the only permanent cure is to extract the affected tooth. In those cases where the area can be reached, an opening, if necessary, can be made through the gum, the root thoroughly scraped and pol- ished, then after washing out the abscessed area, it should be cauterized with some cauterizing agent. Nothing gives better results than phenol- sulphonic acid. With a proper glass syringe and a gold or platinum needle, the remedy can be injected into the abscess pocket. One thorough treatment should effect a cure. In curetting these cases it is far better to go a little beyond the affected territory rather than fail to remove all of the affected tissue and have the abscess recur. Where the abscess can be reached, thorough curettment and cauterization will effect a cure. That portion of the pericemental membrane which has been destroyed will perhaps never be regenerated, but if we succeed in having granulation fill in the area involved, even though the mem- brane is not regenerated over that particular surface of the root, the tooth can be saved for a considerable length of time. Filling Root Canals. — There are so many different methods of filling root canals, and there seems to be such a variance of opinion as to the best method of performing this operation, that it is with a degree of hesitancy that the author attempts to discuss this subject. This operation stands as a sort of dividing line between the subjects of therapeutics and operative dentistry proper. In discussing this subject the author will present the therapeutic aspect and describe a method of procedure which has proved successful in his practice. It will be remembered that three factors were emphasized in the chapter on pulp removal and the subsequent treatment, viz.: 1. Established and maintained asepsis, 2. Preserve the color of the tooth. 3. Thoroughly fill the canal. The author suggests filling all canals, which are large enough for a broach to enter, with gutta-percha in the manner which will be sub- sequently described. In connection with the preservation of the color of the tooth, it should be mentioned that white base plate gutta-percha should be used, especially for the purpose of dissolving in chloroform, or eucalyptol compound, making, respectively, chloro-percha and euca- percha compound. If this white substance is forced into the tubuli of 372 THE TREATMENT OF PUTRESCENT PULPS. the crown of the tooth, as it is liable to be, it will not change the color of the tooth structure as would the pink gutta-percha. A great many dentists have been moistening the canal, previous to filling with gutta- percha, with oil of eucalyptus; and, as a result, much unnecessary pericementitis has followed this operation. If oil of eucalyptus is used at all, the refined oil only should be selected; and, far more satis- factory results will follow the use of eucalyptol, the most volatile con- stituent of oil of eucalyptus. While eucalyptol is irritating, it is not nearly as much so as is oil of eucalyptus. The author suggests modify- ing the irritating property of eucalyptol and enhancing its antiseptic power by combining menthol and thymol as suggested in the prescrip- tion for modified eucalyptol in the chapter on The Treatment of Ordinary Pericementitis. In this proportion the agents added do not interfere with the solvent power of eucalyptol for gutta-percha; but if the amounts are increased to any appreciable extent this does not hold true. In filling root canals it is always the safest practice to adjust the rubber dam, for asepsis must be established and maintained. The same agents can be used for sterilizing the teeth after the dam is ad- justed as were described in removing pulps by the anesthetization method. The canals should be aseptic before the operation is at- tempted. If there is any doubt in this regard the operation should be deferred until the canals are in such a condition. Filling Large Canals. — In filling large canals, especially those in connection with which abscesses have been treated, where the apex is large and where we ought not to expect to get a response from the patient when the gutta-percha cone reaches the apex, on account of the absorption in the apical area, it is best to measure the canal and then use one cone which approximately fits the canal rather than use two or three smaller cones with the possibility of forcing one through the apex and into the apical area. There is almost as much danger of forcing the root filling too far in large canals, as there is in not forcing it far enough in small canals. To measure the canal, cotton can be tightly wrapped around a smooth, sterile broach and inserted. When, by repeated trials the cotton fits the canal, a cone can be made of white base plate gutta-percha, which is slightly smaller than the tightly wrapped cotton. The canal should now be moistened with modified eucalyptol, flooded with white eucapercha compound, working the latter up or down into the canal with a fine smooth broach, exhausting the air. If cotton is wrapped around the broach used for this latter purpose, only a few shreds should be used; for we should avoid making a piston GENERAL CONSIDERATIONS. 373 out of the broach and thus defeating the means of exhausting the air. This accomplished, the cone can be slowly and gently pressed to place. In filling large canals from which live pulps have recently been re- moved, the patient will generally flinch before the cone reaches the apex. When this occurs, we should wait a few moments, when the cone can be gently pressed much farther without causing the patient to flinch a second time. If these precautions are observed, they will be the means of preventing much of the pericementitis following the filling of root canals. Small Canals. — In filling all canals where we can enter nicely with a smooth broach, it is best to follow the technique outlined above, using a cone which will enter the canal. However much we may re- gret it, there are canals, especially in the molar teeth, so small and tortuous that even a fine, smooth broach will not enter; at least to any depth. It is useless to try to fill such canals with a gutta-percha cone. The methods of enlarging the canals by the use of acids and caustics, as referred to in connection with the destruction of pulp tissue in such canals, can be employed; but it is not always advisable to enlarge them sufficiently to admit a small cone. After the larger canal or canals in a multirooted tooth are filled in the ordinary manner, the smaller ones can be flooded with eucapercha compound and this prepa- ration worked up or down into the canal. This process should be kept up for some time until we are certain that all air has been expelled and the canal filled with the plastic material. The sides of the pulp chambers can now be moistened with eucapercha compound and a piece of base plate gutta-percha, selected and softened in the flame, can be packed into the pulp chamber, when pressure can be made towards the small canals and the plastic gutta-percha forced into them. This is much better practice than simply filHng the mouth of the canal with a gutta-percha cone. If the canal is so small and tortuous that even a small broach will not enter, and if it cannot be enlarged by the use of acids or caustics, as referred to in a previous chapter, it is good practice to make a paste of formocresol and thymolized calcium phosphate, placing the paste over the mouth of the canal and, after absorbing the excess liquid with cotton or bibulous paper, covering it with cement. As previously mentioned there are many methods of filling root canals by which good results are attained. The method here outlined has served the author well. In closing this chapter I desire to say that no reasonable amount of time should be considered lost in treat- ing the conditions discussed in this chapter and in properly preparing canals for the insertion of the filling material. CHAPTER XXIIl. THE CAUSES AND TREATMENT OF DISCOLOR- ATIONS OF TEETH. BY J. P. BUCKLEY, PH.G., D. D. S. General Considerations. — In the discussion of the methods of removing pulps from teeth and the subsequent treatment, the treating of putrescent pulps and the various kinds of alveolar abscesses, the author endeavored to emphasize the necessity of preserving or restoring the color of the tooth. There is, perhaps, nothing more annoying to a conscientious dentist and to an appreciative patient than a discolored tooth in the patient's mouth. If the precautions, vi^hich have been mentioned in the preceding chapters, with reference to this factor are observed in the treatment of teeth, the necessity for bleaching may often be avoided ; for after all that has been written on this subject is studied, it must be admitted that the most successful method of bleaching teeth is to so treat them that they will not need to be bleached. There are three principal sources of the discoloration of tooth struc- ture, viz., pulp decomposition, remedial agents and metallic fillings. The greatest source is that of pulp decomposition. Many teeth con- taining putrescent pulps are discolored before the patient presents for treatment. In those cases where the color is not lost the putrescent condition can be corrected and the color preserved by the method of treatment outlined in a previous chapter. There are two ways by which the discoloration is produced, 't. e., by solutions which stain the cement-like substance uniting the tubuli, and by the ingress into the tubuli of insoluble coloring substances. For instance, many remedial agents in solution such as oil of cassia, silver nitrate, etc., have the property of staining the cementing sub- stance and producing discolorations; while the sulphids formed from certain metals, as for example in amalgam fillings, produce discolor- ation by virtue of being forced into the tubular structure of the dentin. If more care were taken in selecting remedial agents, used in the treatment of teeth, which would not stain the tooth structure, and if high grade alloys were selected in making amalgam fillings, the cavity 375 376 CAUSES AND TREATMENT OF DISCOLORATIONS OF TEETH. properly prepared, amalgam inserted and polished when set, there would be few teeth discolored from these sources. Occasionally, however, teeth have been observed to assume a pinkish hue shortly after some traumatic injury, rapid regulation or after the application of some irritating drug had been applied to some small exposure of the pulp as, for instance, arsenic trioxid. It was stated in a previous chapter, that it is always best to apply arsenic trioxid to the dentin immediately over the pulp, even though an exposure exists. Dr. E. C. Kirk, of Philadelphia, has offered a plausible explanation for the cause of this immediate discoloration. He says, ** It is now known that the pink staining of the tooth is brought about by a rupture of the stroma of the red blood disks liberating their contained hemoglobin, which dissolves in the plasma, forming a solution of hemoglobin which readily penetrates the dentinal tubuli, the lumen of which is of insufficient diameter to admit the unbroken red corpuscle. This pink discoloration resulting from the infiltration of hemoglobin solution represents the first stage of tooth discoloration. The pink stain readily undergoes alterations, later on assuming a brownish tint, due to the breaking down of the highly complex mole- cule of hemoglobin into a reduction product known as hematin." But as has been stated, many teeth containing putrescent pulps are discolored before the patient presents for treatment, and inasmuch as this is by far the greatest source it is well to try to ascertain definitely the true cause of the discolorations from this source; for, it is difficult and unsatisfactory to try to bleach a tooth when we have no knowledge of the nature of the pigment we are trying to bleach. The principle which governs the successful bleaching of teeth is to chemically change the molecule of the pigment in such a manner as to destroy its color, or chemically change the insoluble coloring substance to a soluble form, when it can be washed out of the tooth structure. Attention will now be directed to the cause of discoloration from pulp decomposition as the author understands it. In the chapter on the Chemistry of Pulp Decomposition, the intermediate and end-products resulting from this complicated process were enumerated and it was ascertained that ammonia, NH,, and hydrogen sulphid, H^S, were the principal gases formed. It was also pointed out that the relative amount of nitrogen and sulphur found in the proteid molecule was fifteen per cent of the former to 0.3 per cent of the latter; and from this fact it was reasoned that ammonia, a compound of nitrogen and hydrogen, was generated in far greater quantities in a putrescent root canal, than hydrogen sulphid, a compound of hydrogen GENERAL CONSIDERATIONS. 377 and sulphur; and that this latter gas did not assume the important r61e in the discoloration of teeth from this source, as had been so generally supposed. It is quite generally conceded by those who have given this phase of the decomposition process their attention, that iron, Fe, is the most important element to be considered in the many factors entering into the discoloration problem; and it is a common statement found in our text-books and journals that the discoloration is due to the formation of ferrous sulphid, FeS, which salt is supposed to be formed by the action of hydrogen sulphid upon the iron. This view is held by many writers, among whom is Dr. Kirk, who has perhaps given more thought to this subject than any other writer. The source of iron has been considered entirely from the decomposition of the hemoglobin of the red blood corpuscles; for it is well known that this compound contains iron, which is not characteristic of all proteid bodies. Dr. J. E. Hinkins, of Chicago, in his analysis of the enamel and dentin of human teeth, found that iron existed in both of these structures in combination with aluminum. It is not unlikely that future investigation will find that the iron from this source plays a part in the discoloration of tooth structure. It remains, however, to be demonstrated that ferrous sulphid is the true cause of the dis- coloration and the author doubts if this theory can ever be proved to be correct. From chemistry we learn that ferrous sulphid is a Uack compound and that no change takes place in the color or other- wise by exposing it to the air. Should the discoloration of tooth structure be due, then, to ferrous sulphid, as claimed by many writers, there would be no necessity, in treating putrescent pulps, so far as preserving the color of the tooth is concerned, for using a remedy which can be hermetically sealed within the tooth. Clinical ex- perience shows that a tooth containing a recently decomposed pulp, in a large percentage of cases, is not discolored, and that such a tooth will not change in color if the formocresol remedy is used in the treatment and always hermetically sealed. Dr. Kirk admits that, "Ferrous sulphid, as such, cannot be held wholly accountable for the bluish-black color of the tooth which has reached the stage of permanent discoloration." Neither can the green nor yellow discolorations of teeth be attributed in any way to the presence of black ferrous sulphid; yet, the author is of the opinion that it is possible for this compound to be formed in the ultimate process of pulp decomposition as will be explained later on in this chapter. From the foregoing, it must be evident that it is necessary to search 378 CAUSES AND TREATMENT OF DISCOLORATIONS OF TEETH. for Other colored substances, besides black ferrous sulphid, which are possible to be formed in the process of pulp decomposition and which are capable of staining the tooth structure. In articles which the author read before the Odontographic Society of Chicago {Dental Review, June, 1901, October, 1902), a theory was advanced which explained the variety of colors exhibited in dis- colored teeth, and while some criticism has been offered in regard to this theory, he is still of the opinion, that it presents today the most rational solution of this question from both the chemical and clinical viewpoint. As has been stated, ammonia is not only a constant end-product, but it is generated in far greater quantities than any other gas. It is well known that ammonia has the property of uniting chemically with water, which is always present in a putrescent root canal, form- ing ammonium hydroxid, NH3 -I- H^O = NH^OH. This reagent will act upon the soluble salts of iron, in both the ferrous and ferric forms, producing respectively, ferrous and ferric hydroxid, Fe(0H)2, Fe,(OH)6. Therefore, it is not only possible, but quite probable, that the atomic iron which is liberated in the process of decomposition, from the hemoglobin or perhaps intermediate compounds containing it, unite with the ammonium hydroxid present, forming the hydroxid of the metal; and inasmuch as the compounds containing the iron are organic or weak, the ferrous hydroxid, in all probability, would be produced. Ferrous hydroxid is a white compound which readily absorbs oxygen when in the moist state and exposed to air, and grad- ually changes to ferric hydroxid, a reddish-brown compound. In this change there is an array of four distinct colors — white, green, black and brown — and in the blending of these four colors there is produced every variety of shades exhibited in discolored teeth. This seems to suggest a plausible explanation as to why teeth containing putrescent pulps change color when air is admitted; also why a tooth containing a recently decomposed pulp is not discolored and does not readily change color until air is admitted. I fully recognize the fact that ferrous hydroxid is not the only compound of iron capable of producing color changes when moist and exposed to air. Nearly all of the ferrous compounds change more or less; but with the possible exception of ferrous carbonate, which could be formed, ferrous hy- droxid is the only compound of iron possible to be produced, the color changes of which correspond to those seen in teeth which tiave reached the stage of permanent discoloration. I have stated in this chapter that, in my opinion, it was also possible GENERAL CONSIDERATIONS. 379 for ferrous sulphid to be formed ultimately by the putrefactive process; but it can only be produced by the hydrogen sulphid acting first upon the ammonia, forming ammonium sulphid, H^S + 2NH3 = (NHJ,S. This alkaline reagent will act upon the soluble salts of iron, precipi- tating the metal as ferrous sulphid. My conclusions, then, with reference to the true cause of the discoloration, are these: that the permanent yellow discoloration is due to the formation of ferric hydroxid ; the bluish-black discoloration to a mixture of ferric hydroxid and ferrous sulphid — or to a failure of the ferrous hydroxid to become completely oxidized into the ferric form owing to a lack of moisture or oxygen; the other colors observed are transitory and are due to the gradual transition of the ferrous into the ferric hydroxid. In coming to these conclusions I have accepted the statement that iron plays the most important role of all the elements entering into the discolor- ation problem; for if it were possible to remove the hemoglobin from the blood or the iron from the hemoglobin, I do not believe the dentin could be discolored by any compound possible to be formed by the process of pulp decomposition. If this be true, my reasoning is at least logical. Having thus far, in this chapter, discussed the cause of the dis- coloration of tooth structure, the methods of restoring the normal color will now be considered. When a case presents for bleaching there are three important things to be determined: (i) Ascertain, if possible, the cause of the discoloration. (2) Decide whether or not the color can be successfully restored. (3) The selection of the proper bleaching agent with which to restore the color. The general cause of the discoloration can usually be ascertained from the history of the case as related by the patient. Whether or not the tooth can be successfully bleached depends largely upon the cause of the discoloration, the condition of the tooth structure, and the length of time the tooth has been discolored. Experience will prove that the teeth which will permanently retain their color, after it is restored, are those that have a good bulk of dentin and which dentin can be protected by the remaining enamel and some filling material, preferably porcelain if this material is at all indicated. I desire to emphasize the fact that it is folly to expect a tooth to retain its color- any length of time after once being bleached unless ihe dentin is properly protected. Having ascertained the cause of the discoloration and believing 380 CAUSES AND TREATMENT OF DISCOLORATIONS OF TEETH, that the condition of the tooth structure justifies us in attempting ta bleach the tooth, we come to the most important consideration, viz., the selection of the bleaching agent, with which the color can be restored with the least inconvenience to the patient and operator. Methods. — All of the methods employed in bleaching teeth involve more or less chemistry; and from a chemical viewpoint there are two general methods of bleaching teeth — oxidation and reduction. I. Oxidation Method. — This general method is of two kinds also direct and indirect. (i) Direct. — By direct oxidation is meant the use of any agent or agents from which oxygen can be directly obtained. The agents used for the purpose are: Sodium dioxid, NajO.^. Twenty-five per cent ethereal solution of hydrogen dioxid. HjOj. Alphozone, (COOH. CHj. CH^CO),- O2. Aluminum Chlorid, AljCl^, and a three per cent aqueous solution of hydrogen dioxid. Oxalic acid, HjCjO^. 2H2O. (2) Indirect. — By indirect oxidation is meant the use of any agent or agents by which oxygen can be obtained indirectly. The agents employed are such as will liberate nascent chlorin, CI, a chemic- ally active gas, which, in the presence of moisture seizes upon a molecule of water, HjO, abstracts the atoms of hydrogen, H, forming hydrochloric acid, HCl, and liberates the oxygen, O, in the nascent state, as HjO + 2C1= 2HCI + O (nascent). Some of the agents used for this purpose are: Aluminum chlorid and a freshly prepared Labarraque's solution (Harlan). Chlorinated lime and dilute acetic acid (Truman). Powdered alum, Al2K2(SOj4, and Labarraque's solution. Solution of sodium chlorid electrically decomposed. II. Reduction. — By reduction is meant the use of any agent or agents which will abstract oxygen from a compound containing it. The agents which have been recommended are, sodium sulphite, Na^SOj, 10 parts, and boric acid, H3BO3, 7 parts. These are mixed and placed within the tooth, moistened with water and her- metically sealed. (Kirk.) A reaction occurs between the two sub- stances with the ultimate formation of sulphurous acid which has a great affinity for oxygen and is therefore a good reducing agent. In some cases where the tooth has been discolored by remedial agents and where it is desired to break up the color molecule, good results are obtained by this method. Whenever the method is used the GENERAL CONSIDERATIONS. 381 tooth should subsequently be thoroughly washed with an alkaline solution such as a ten per cent solution of sodium bicarbonate or borax to neutralize the acid. In most cases of discoloration the direct oxidation method is preferable and in view of the fact that all of the agents used in the direct method of bleaching depend upon the generation of oxygen for their efficacy, it can readily be understood that the direct method is far more satisfactory. The fact, also, that hydrochloric acid is a constant by-product in the indirect method, thereby creating an acid medium, adds to the objectionable features of this method; for manu- facturers have recognized for years that better results can be obtained in bleaching ivory, wool, hair, feathers, etc., when the bleaching process was carried on in an alkaline medium. This is likewise true in bleach- ing teeth. Believing then, that the direct oxidation method is far superior to the indirect, I shall not burden my readers by describing the latter method; but will direct attention to the detailed use of sodium dioxid — a direct oxidizing agent and one which, if its chemical prop- erties are known and its dental application understood, the author believes to be the best agent for bleaching teeth thus far suggested to the profession. Sodium dioxid was introduced by Dr. Kirk in 1893. It is a rare chemical, not because it is difficult to manufacture, but because of the fact that in the past there has been little demand for it. Its chemical activity precludes its use on soft tissue; hence, it is scarcely known to the medical profession, and is not kept in many pharmacies. It is the oxid formed when sodium is allowed to burn briskly in dry air or oxygen. The product occurs in commerce as a yellow powder and is readily decomposed by water into caustic soda and oxygen. Because of this latter fact, much of the product obtained from whole- sale druggists, labeled "sodium dioxid," is nothing but caustic soda. This accounts for the fact that many dentists have tried this method of bleaching and failed to get results. The fault is not with the method, but with the powder used. In order that we might be able to ascertain the efficacy of the chemical, some years ago I devised a simple chemical test for this purpose. In a clean, dry test tube place about one gm. (15 grs.) of the powder and to it add i or 2 c. c. (15 or 30 m.) of water. If the specimen is good sodium dioxid, enough oxygen should be generated to kindle a glowing splinter held at the mouth of the tube. Having tested the chemical and proved it to be sodium dioxid, and not caustic soda, the next thing is to properly prepare the tooth, which, of course, should have been previously treated and the root filled with 382 CAUSES AND TREATMENT OF DISCOLORATIONS OF TEETH. gutta-percha. The rubber dam should be adjusted, if possible without the use of the steel clamp. The ligature should be wrapped twice around each tooth included in the dam, which should be at least two teeth on either side of the one to be bleached. This will prevent the by-product, caustic soda, from getting on the soft tissue and destroying it. The lower third of the root filling should now be removed with a good sized round bur — it being necessary, for permanent results, to bleach the tooth rootwise as far as possible. We are now ready to apply our bleaching agent. Both the dry sodium dioxid and a solution made by carefully dusting the powder into ice water is recommended to be used. The best results are obtained by using the dry powder, placing it into the cavity and with a platinum broach or pointed glass instrument, work the powder well up into the canal from which the root filling has been removed. Care should be taken not to use steel instruments, as the oxygen will attack the steel forming ferric oxid and therefore we may get into the tooth the pigment we are trying to remove. In some cases it is rather difficult to place the powder in the cavity without getting it on the patient's face or clothing. To over- come this a strip of unannealed i.iooo platinum foil can be placed between the discolored and adjacent tooth, letting it extend above or below the cutting edge, as the case may be, when white base plate gutta-percha can be warmed and pressed against the lingual surfaces of the teeth included in the dam. This forms a pocket on the labial side into which the powder can be easily placed, using a little gold or platinum spoon or spatula. In more difficult cases a paste can be made of the powder and chloroform, in which it is insoluble, quickly packing the paste into the cavity, evaporating the chloroform, leaving the dry powder where it is desired. Distilled water is now dropped upon the powder, causing a lively effervescence and the following reaction takes place: Na^^O^ + H2O = 2NaOH + O (nascent). This nascent oxygen is a powerful oxidizing agent. It attacks and rapidly destroys any organic matter which may be present in the tubular structure of the dentin. It also thoroughly bleaches vegetable colors and acts upon any iron compounds which may have produced the discoloration. It converts ferric hydroxid, if present, into ferric oxid — still an insoluble compound. If ferrous sulphid is present in the moist state, it may be converted into ferrous sulphate, a soluble salt; but in the presence of caustic soda it would be reprecipitated as ferrous hydroxid, which, in turn, in the presence of oxygen, is at once reconverted into ferric oxid. Therefore, the pigment to be removed if our chemical reasoning is correct as to the cause of the discoloration GENERAL CONSIDERATIONS. 383 from pulp decomposition, is ferric oxid, an insoluble compound and must be removed mechanically by washing the tooth. Its removal is facilitated by the by-product, caustic soda, acting upon any fatty substances — fat being an end-product of the putrefaction of the proteid material — which may be present in the tubuli. The result of this action being a soluble soap, the removal of which by washing, aids, as stated, the mechanical removal of the insoluble pigment. It is my opinion that the ultimate success depends quite as much upon the mechanical removal of the coloring matter as upon the chemical destruction of it; therefore, the necessity for thoroughly washing the tooth after each application of the bleaching agent. Warm distilled water should be used in a strong syringe, letting a moist sponge absorb the water. The cavity is now dried, the color of the tooth observed and the process repeated, if necessary. Usually two or three applications are sufficient. If the color is not readily restored, the dentin can be saturated with a two per cent solution of sulphuric acid which can now enter the tubuli and chemically convert the oxids, that may not have been mechanically or other- wise removed by the saponifying and washing process, into sulphates. The salts produced are freely soluble and can readily be washed out by again using the warm water. When the tooth is satisfactorily bleached, a paste of precipitated calcium phosphate and distilled water can be placed in the cavity, packed into the lower third of the root and burnished, with a warm burnisher, against all exposed dentin. This is thoroughly dried by burnishing, the excess removed, and a light-colored, quick-setting cement used to form a base for the final filling which had better be inserted before the dam is removed. In conclusion I desire to say that in the bleaching of teeth we find a practical application of the science of chemistry to the practice of dentistry; and that in the discoloration of tooth structure from the various sources can be found a fruitful field for further investigation. CHAPTER XXIV. THE TREATMENT OF CHILDREN'S TEETH. BY C. N. JOHNSON, M. A., L. D.S., D. D. S. This subject naturally divides itself into two parts — the man- agement of the child, and the management of the teeth. Tempera- mentally, physically and nervously there is so much difference in children that to ignore this factor and prescribe a set method of practice for all cases would result in confusion, failure and disaster. The first visit of a child to the dentist is usually a momentous occasion. Sometimes it is undertaken with the direst dread, at others with the most eager anticipations; all dependent on the point of view given the child by the parent. The dentist's duty is to study the temperament of the child most carefully, and he should not con- tent himself with anything short of obtaining a perfect mastery over the child, at least during the time the latter is in his office. The means to be employed in gaining this mastery are as varied as are the manifestations of juvenile human nature — probably the most varied of anything in psychological study. The chief factor, the fundamental basis of success in controlling children, is the exhibition of extreme kindness and the cultivation of infinite patience. Unless a dentist can bring this kind of an attitude to the management of his young patients he would better not attempt their treatment. And yet there are some children so unruly by nature and so spoiled by false training at home that to obtain com- mand over them in the dental chair the operator must be firm with them almost to sternness. If the parent has no control over the child, as is sometimes unfortunately the case, then the dentist should be the means of giving the child what is probably its first real lesson in discipline. And let it be said that no class of men, not even medical practitioners, are placed in so favorable a relationship to these young patients for the purpose of instilling into them obedience and stability of character as is the dentist, and if the members of our profession would only rise to the possibilities of their opportunities in this regard they would do no small part in developing true manhood and woman- hood in the rising generation. To bring up a child with no idea of 25 385 386 THE TREATMENT OF CHILDREN'S TEETH. individual responsibility, to foster a tendency toward avoiding any duty of a disagreeable nature, to always sprinkle roses for the child to tread upon, is weakening in its effect and results in deterioration of character and the pitiable failure to meet the emergencies of life as they inevitably arise. A discriminating dentist can do much in his professional relation- ship with these young minds to develop in them stamina and force of character, and it is sometimes the case that the first real experience of facing and properly meeting an issue is fought out in the dental chair. To be successful in the management of children under these trying circumstances a dentist must be a rare student of human nature, and he should early learn just when to be yielding and tender, and when to be firm as adamant. But Ifet it always be remembered that under no circumstances, however trying the case may be, should he allow himself to lose his own self-control and display temper or im- patience; and whenever it has been necessary to be firm and e\en severe, he should invariably soften his demeanor by the utmost kind- liness and an unmistakable interest in the little patient's welfare. To gain complete control of a child who previously has never been controlled by any one is no mean achievement, and the sense of satisfaction in the good attained is well worth all the eflfort it requires to accomplish it. One feature of the management of children in the dental office which in this enlightened age of child study would seem unneces- sary of mention, but which unfortunately is still a factor in some instances, is the habit of deceiving the child as to what is to be done. There is no more fatal error, no more disastrous or appalling wrong, than to deliberately deceive a child, and the result of one such decep- tion can never be fully estimated. To the dishonor of some parents we are occasionally asked even in the beginning of the twentieth century to become a party to such an iniquitous practice, but no dentist of any self-respect or manhood will ever enter into such a conspiracy. It is always well, of course, to destroy in the mind of the little patient any sense of fear by making as light as possible of the probable severity of the operation, and by the utmost tenderness and gentleness of demeanor; but to deliberately assure the child that a certain operation will not hurt in the least w^hen it is almost certain to hurt, and worse than this to pretend to be applying some medicament to a tooth and then suddenly seize it with the forceps and extract it is a monstrous and cruel wrong. Ordinarily the first visit of a child to the dental office should THE TREATMENT OF CHILDREN'S TEETH. 387 be SO managed, if possible, that no work of a disagreeable nature is undertaken. Mothers should be instructed to bring their children early, even before the necessity seems apparent, so that the child forms the habit of having the teeth examined and gets acquainted with the dentist. Thus, when fillings have to be made the ice is already broken and the way made easier. If the case has been deferred till toothache occurs, and the visit is one of necessity for relief, the only operative procedure undertaken at this time should be merely to stop the pain. A sympathetic and personal interest should be manifest for the little sufferer, and the impression formed at this first visit that the dentist is a kind hearted gentleman and not at all to be feared. When once confidence is attained it will usually be found that most children will tolerate any necessary discomfort in having their teeth cared for provided their pride is appealed to in the proper manner and they are upheld as little men and little women. But the dentist should have a care not to overtax the courage of a delicate child, and should constantly watch with the keenest eye for signs of wavering or undue nervous tension during an opera- tion. It is sometimes better to do temporary work and retain the confidence of the child than to always attempt permanent operations- and thereby run the risk of creating distrust and dread. This is particularly true of operations on the deciduous teeth where the object is more to keep them comfortable for a few years than to do- artistic and permanent work. The materials for filling deciduous teeth are limited to those- easy of insertion and not too exacting in their requirements. When. cavities occur in the proximal surfaces of the incisors they are usually better managed with oxyphosphate of zinc than with anything else.. They are ordinarily shallow, and the fact that they are frequently quite sensitive prevents the operator from giving them any appreciable retentive form. Cement can therefore be used when nothing else will remain in place. These teeth do not often call for much operative interference owing to their early loss to make way for the permanent incisors, but with the deciduous molars the case is different. They remain four or five years after the incisors are gone, and the problem. of saving them when they decay is sometimes exceedingly difficult. They should be given early and frequent attention when the mouth' is susceptible to caries, with the aim always of checking the disease and keeping the teeth comfortable for mastication. The reason for this is not only that the child shall be enabled to properly prepare the food for digestion during these early years, which of itself is very 388 THE TREATMENT OF CHILDREN'S TEETH. important, but that proper habits of mastication are established at this impressionable age. If the deciduous molars are allowed to decay and become sensitive the child involuntarily forms the habit of bolting the food without proper mastication, and this habit once formed is likely to persist through life. There are many people today who do not masticate their food to the extent which their present masticating apparatus would warrant simply because they have formed the bad habit of bolting their food during youth. Simple cavities in the occlusal surfaces of these teeth are not difficult to manage. They may be filled with oxyphosphate of zinc, oxyphosphate of copper, pink base-plate gutta-percha or amalgam, as is indicated in the individual case. Amalgam is more reliable than either of the others provided a proper preparation of the cavity may be made and it does not reach too close to the pulp, but sometimes we are obliged to temporize with cement or gutta-percha. The most difficult problem we meet in the management of de- ciduous teeth is to properly treat cavities occurring in the proximal surfaces of the molars. There are several factors in these cases tending to make them troublesome to control. They are usually sensitive, making them difficult of proper preparation for the reten- tion of amalgam, which is the only permanent material we have for preserving them. Unless fillings are reasonably well anchored in these cavities they are likely to be loosened by mastication, and if we attempt too deep anchorage we endanger the pulp. In fact these teeth do not usually present much area of tooth tissue in which to form a cavity and it takes but little penetration of decay to involve the pulp. It is always best to avoid irritating the pulp if possible, and to this end it is frequently advisable to use some other kind of material than metal to fill them. Much of the discomfort experienced by children in mastication is due to the packing of food in the interproximal spaces wherever decay has occurred in these surfaces. If cement is used it very rapidly wears away so as to present a space between the teeth and thus invite a lodgment of food. Not only this but frequently we find the teeth drifting slightly apart as the jaw expands preparatory to the eruption of the permanent teeth, all of which increases the difficulty. In cases where amalgam cannot be used and cement is unreliable the patient may be made more comfortable with gutta-percha than any other material, though this is, of course, more or less temporary in its service. The problem is greatly complicated where two cavities face each other, and in some instances the surest method of making the teeth TREATMENT OF PERMANENT TEETH DURING CHILDHOOD. 389 serviceable for mastication is to bridge across the interproximal space from cavity to cavity with gutta-percha. This is the only material by which two cavities may be joined in this way on account of the individual movement of the teeth. If a rigid material like cement or amalgam is used the filling will very shortly be loosened from one cavity or the other, but gutta-percha being more or less yielding will accommodate itself to the movement of the teeth with- out injury. If this plan is followed provision must be made to pre- vent the gutta-percha from being forced down between the teeth in the interproximal space, and this may be accomplished effectively by placing a metal guard of gold, platinum, or German silver across the interproximal space allowing the ends to rest on the gingival walls of the cavities and building the gutta-percha over it. This protects the gum most perfectly and admits of serviceable mastica- tion without discomfort. As the gutta-percha is worn away it may be renewed from time to time, and although this is at best a tem- porary operation yet it is in some of these troublesome cases the only procedure by which the teeth may be made serviceable. In pulpless deciduous molars the case should be treated in the usual way, except that some care should be taken not to introduce medicines which have a disagreeable taste or odor. It is always desirable with children to avoid as much as possible anything which tends to create prejudice against having dental operations performed, and usually these deciduous cases may be brought under control by the use of the essential oils which are less objectionable than some of the more powerful antiseptics. TREATMENT OF THE PERMANENT TEETH DURING CHILDHOOD. From the time the permanent teeth begin to erupt at about six years of age till the deciduous teeth are all lost and replaced by permanent ones at about twelve the care of the erupting teeth is a very important consideration, and in mouths where there is great susceptibility to decay of the teeth the problem of saving the permanent ones is some- times perplexing. When the incisors begin to decay in the proximal surfaces shortly after their eruption it is seldom that we can insert permanent fillings in them at once. It is, of course, better if this can be done, thus making one operation sufficient and creating in the mind of the patient the impression that dental operations are effective when properly performed. But there are many patients who lack the fortitude at such a tender age to go through the necessary tension to have thorough 390 THE TREATMENT OF CHILDREN'S TEETH. work performed, and it is better to make several operations on the one tooth at different times and preserve the courage of the child than to attempt a perfect piece of work at the outset and break the spirit of the patient, thus creating a dread of having dental work done. But let it be borne in mind that just so soon as it is found possible to have the temporary fillings replaced with permanent ones this should be done. In these susceptible cases the teeth can never be made too secure against decay even by the very best work the operator is capable of, and it is therefore well not to trust to temporary work longer than necessary. But in this connection it should be said that the attempt to use gold before the child is sufficiently under control to admit of doing a perfect piece of work will as certainly lead to failure as will the use of other .materials more temporary in their nature. We must have a good technique in any operation calculated to be permanent and the requirements of gold in this respect are more exacting than for any other filling. In some instances we may employ inlay work in children's teeth before they will tolerate the exactions of gold foil filling and thus obtain a better result than by the use of any of the plastic materials. Each case should be studied carefully with the idea of learning the temperament of the child and knowing how to gain such control as shall permit of the best service. The practice of dentistry in its highest attainment is a constant study of conditions, conditions of the mind, conditions of the teeth, conditions of the surrounding parts — all of which materially affect us in the treatment of every case. And in this connection there is no other one thing of equal importance in the ultimate saving of the teeth and the maintenance of a healthy mouth than the establishment during these early years of the correct principles and practice of oral hygiene. It is not the province of the present chapter to go fully into this phase of the ques- tion, but it should be said in passing that no dentist is doing his full duty to the rising generation who fails to impress upon his young patients the importance of properly caring for the teeth and gums, or who does not give full instructions as to how this should be done. This should also be followed by a constant surveillance to see that his instructions are carried out. A very necessary consideration in the treatment of children's teeth is to watch carefully the condition of the first permanent molar. This tooth is one of the most important in the entire arch. It is the chief standard bearer of the jaws during the period when the de- ciduous teeth are being lost and the other permanent teeth are coming TREATMENT OF PERMANENT TEETH DURING CHILDHOOD. 391 into place, and if lost early it invariably results in the jaws dropping closer together than normal which detracts materially from the force of character of the face. If it is lost subsequently to the eruption of the second permanent molar and the bicuspids it produces a tipping of the other teeth into the space so as to disarrange the occlusion. No arch is ever perfectly normal with the first permanent molar missing, and even in those cases where the space has entirely closed by the approach of the second molar and bicuspid and where the occlusion seems good from the buccal aspect it will be found defective if models are made and a careful examination is given the lingual aspect. In view of its early eruption it is peculiarly susceptible to decay, and should therefore be watched most carefully and preserved by filling. Where it has been extensively broken down by caries before it comes to the dentist it may usually be restored to full functional usefulness by the inlay method, and no pains should be spared to place it in a condition of health and service. As has already been stated, one of the chief functions of the dentist in his treatment of children is to educate them to the importance of properly caring for the teeth, and in respect of the first permanent molar it may be said that this education should begin with the parent before the child is of responsible age so that the frequent error of mistaking this tooth for a deciduous one and allowing it to go by default should not be committed. Parents should be instructed to bring their children to the dentist not later than the third or fourth year, and then the cooperation of the dentist, the parent and the child should result in every individual growing up with a good, serviceable set of teeth. CHAPTER XXV. LOCAL ANESTHESIA. BY HERMANN PRINZ, A. M., M. D., D. D. S.' History. — The elimination of pain during surgical operations is inseparably interwoven with the history of the human race. It has always been the aim of those interested in the cure of bodily ills to relieve pain in some empirical manner. The efforts to solve the riddle of painless operations were, however, seemingly so very futile that even as late as 1832 Velpeau was led to express his pessi- mism as follows: "To escape pain in surgical operation is a chimera, which we are not permitted to look for in our time." Little did he expect that he stood at the very threshold of the discovery of anes- thesia and that less than a decade later the " nirvana" of painless opera- tions would be an accomplished fact. And when Dieffenbach, in 1847, wrote these classical words regarding the use of ether as an anes- thetic, "the beautiful dream, to eliminate pain, has become a fact — pain, the highest consciousness of our earthly existence, its clearest con- ception of the imperfections of our body, it has to bow low before the powers of the human mind," the world at large awakened to the fact that pain had been conquered. The discovery of anesthesia is essentially to be credited to the dental and medical profession of the United States, and the names of Crawford W. Long, Horace Wells, William P. G. Morton and Charles F. Jackson are inseparably connected with it. "If America has contributed nothing more to the stock of human happiness than anes- thetics, the world would owe her an everlasting debt of gratitude," said the late Samuel D. Gross, the eminent surgeon, who had ample opportunity to observe in his own operating room the most remarkable changes that followed the introduction of anesthetics. From an historical viewpoint, comparatively few important methods for the purpose of locally obtunding pain are to be recorded prior to the introduction of cocain. The compression of nerve trunks for the abolition of pain seems to be of an old and unknown origin, which was 393 394 LOCAL ANESTHESIA. revived by Guy du Chauliac and Ambroise Par6, and finally found a permanent place in surgery as the Esmarch elastic bandage. Physic- ally reducing the temperature of a part of the body by the application of cold was instituted much later. Bartholin and Severino introduced this method in the middle of the sixteenth century. It became a lost art, however, until John Hunter, of London, again called attention to its benefits by demonstrating it upon animals, and Larray, the chief surgeonof Napoleon's army, employed it for amputating purposes (1807). James Arnott, in 1849, utilized a freezing mixture, consisting of ice and salt, as a means of producing local anesthesia. Through the efforts of Sir B. W. Richardson, in 1866, it was placed on a rational basis by the introduction of the ether spray. The various narcotics which were employed for internal purposes were also made use of as local applica- tions. Mandragora, henbane, aconite, the juice of the poppy head, and many other analgesic drugs enjoyed a world-wide reputation. There is probably no other medicinal plant around which clusters more mysterious and quaint associations than Mandragora. It should be remembered, however, that mandrake, or mandragora (atropa mandra- gora) , must not be confounded with American mandrake, or May apple (podophyllum peltatum), to which it bears no relation. The empirical search for new methods and means pressed the mysticism of the electric current into service, opening a prolific field to the charlatan, which even to this day has not lost its charm. Rich- ardson's voltaic narcotism for a time attracted the attention of the medical and dental profession. Its inventor claimed "that by the action of a galvanic current, passing through a narcotic solution, held in contact with the part to be operated upon, some of the narcotic sub- stance passed much more rapidly into the tissues and that in many instances complete local anesthesia was in this way produced by solutions which are entirely inert when applied, even to the most deli- cate tissue, without the galvanic current." This very same principle, discovered by Reuss in 1807, and introduced by him as "electric endosmosis," or as "cataphoresis," by E. du Bois-Raymond, was "newly discovered" and reintroduced into dentistry about a decade ago. In cyclonic fashion it swept over the globe, but today it is almost forgotten. Electric or galvanic anesthesia was suggested as far back as 1851 by A. Hill, of Connecticut. Francis, in 1858, recommended the attachment of the electric current to the well-insulated handles of the forceps for the painless extraction of the teeth, and, as dental de- pots offer appliances of this nature for sale, it seems that this method is still in vogue with some operators. According to Regner and Didsbury, LOCAL ANESTHESIA. 395 as cited by Sauvez, a current of electricity of high frequency, when directed toward the long axis of a tooth for a shorter or longer period previous to its extraction produces insensibility to pain. In 1880 Bon- will suggested his method of "rapid breathing as a pain obtunder," which he claimed "produces a similar effect to that of ether, chloroform and nitrous oxid gas in their primary stages." In the early days of modern dentistry many feeble efforts were made to alleviate pain during trying operations. Chloroform, alcohol, ether, aconite, opium, the essential oils, and many other drugs were the usual means that were employed, either separately or as compounds, usually under fanciful names, for such purposes. Snape's calorific fluid, composed of chloro- form, tincture of lemon balm, and oil of cloves; nabolis, consisting of a glycerid of tannic acid and a small quantity of chloral hydrate; Morton's letheon, which was sulphuric ether mixed with aromatic oils, are ex- amples of proprietary preparations which enjoyed quite a reputation in their time. In 1853 Alexander Wood introduced a method of general medication by means of hypodermic injections, and a few years later the French surgeon Pravaz modified the old style syringe for this special purpose, which since is known as the "Pravaz" or hypodermic syringe. At once it was suggested to apply such drugs as morphine or tincture of opium for the purpose of producing local anesthesia. The results were not encouraging, however, until cocain was advocated. Cocain was discovered by Neimann in 1859, but it required twenty-five years to make known the remarkable anesthetic properties which this alkaloid possesses when appHed in the ready soluble form of its hydrochloric salt. It was on September 15th, 1884, that Carl Koller, of Vienna, pre- sented this epoch-making communication at the Ophthalmologic Con- gress at Heidelberg, in which he demonstrated the effects of cocain as a local anesthetic. With the introduction of this drug into therapeutics local anesthesia achieved results which were beyond expectations, and its final adoption created a new era in local anesthesia. Means of Producing Local Anesthesia. — The term anesthesia (without sensation), which was suggested in 1846 by the great physician- litterateur, Oliver Wendell Holmes, to Dr. Morton, is usually defined as an artificial deprivation of all sense of sensation, while the mere absence of pain is referred to as analgesia. Correctly speaking, the term local anesthesia is partially a misnomer. In producing local anesthesia we do not fully comply with all the requirements that anesthesia demands, because a part of the sensorium — the sense of touch for instance — is not abolished. The term local anesthesia has, however, acquired such uni- versal recognition that it would seem unwise to recommend a change. 396 LOCAL ANESTHESIA. Anesthesia may be artificially produced by inhibiting the sensory nerve fibers at their central end-organs in the brain or at their peripheral end-organs in the tissues, thus producing general and local anesthesia. Local anesthesia may be obtained in two definite ways. We may in- hibit the function of the peripheral nerves in a circumscribed area of tissue, and we refer to this process as "terminal anesthesia," while, if we block the conductivity of a sensory nerve trunk somewhere between the brain and the periphery, we speak of it as "conductive anesthesia." Conductive anesthesia may be produced by injecting into the nerve trunk proper — endoneural injection — or by injecting into the tissues surrounding a nerv^e trunk — ^perineural injection. The latter form is the usual method pursued when conductive anesthesia for dental pur- poses is indicated. Specific forms of local anesthesia may also be pro- duced by paralyzing the sensory ganglia in the brain or in the spinal cord; these methods have, however, no bearing on the subject under consideration. The successful practice of local anesthesia involves the carefully adjusted co-operation of a number of important details, each one constituting a definite factor in itself, which, when neglected, must necessarily result in failure. As a whole, the practice of local anes- thesia by the hypodermic method represents the composite of the follow- ing factors: 1. A solution of active ingredients corresponding to the physical and physiologic laws which govern certain functions of the living cell. 2. A carefully selected hypodermic armamentarium. 3. A complete mastery of the technique. 4. A proper selection of the correct method suitable for the case on hand. 5. Good judgment of prevailing conditions. Physiologic Action of Anesthetics. — According to more recent thera- peutic conceptions, it is generally recognized that a drug or combi- nation of drugs which simultaneously produce local anemia and inhibi- tion of the sensory nerves in a circumscribed area of tissue is the logical solution of the question of local anesthesia. Certain important factors, however, relative to the physiologic and physical action of the solution employed for hypodermic injection upon the cell govern the successful application of such methods. It is of prime importance, therefore, to comply with the laws regulating the absorption of injected solutions — osmotic pressure. If we separate two solutions of salt of different concentration by a permeable animal membrane, a continuous current of salt and water LOCAL ANESTHESIA. 397 results, which ceases only after equalization of the density of the two liquids — that is, until equal osmotic pressure (according to the Boyle- Van't Hoff law) is established. The current passes in both directions, drawing salt from the stronger to the weaker solution, and water vice versa, until osmotic equilibrium is obtained. The resultant solutions are termed, according to De Vries, isotonic. Osmotic pressure is a physical phenomenon possessed by water and all aqueous solutions, and is dependent on the number of molecules of salt present in the solution and on their power of dissocia- tion. In organized nature these osmotic interchanges play an impor- tant role in regulating the tissue fluids of both animals and plants. In the animal tissue the circulation depends principally upon the mechanical force exerted by the heart. The life of the cell depends on the continuous passage of these fluids, which furnish the nutrient materials, consisting of water, salt and albumin. These chemicals are normally present in certain definite proportions. The membrane of the living cell is, however, only semi-permeable — that is, the cell readily absorbs distilled water when surrounded by it. The cell becomes macerated, loses its normal structure, and finally dies. If on the other hand, the surrounding fluid be a highly concentrated salt solu- tion, the solution absorbs water from the cell; no salt molecules enter into the cell body proper. The cell shrinks, and finally dies. This process of cell death is, in general pathology, referred to as necrobiosis. Another important factor teaches that all aqueous solutions that are isotonic possess the same freezing point — that is, all solutions possessing an equal freezing point are equi-molecular, and possess equal osmotic pressure. This law of physical chemistry has materially simplified the preparation of such solutions. The freezing point of human blood, lymph, serum, etc., has been found to equal approximately 0.55 degrees C, which in turn corresponds to a 0.9 per cent sodium chlorid solution. Such a solution is termed a physiologic salt solution. In the older works on physiology a 0.6 per cent sodium chlorid solution is referred to as a physiologic salt solution, and corresponds to the den- sity of the blood of the frog. A slight deviation above and below the normal percentage of the solid constituents is permissible. When physiologic salt solution at body temperature is injected into the loose connective tissues under the skin in moderate quantities, neither swelling nor shrinking of the cell occurs. A simple wheal is formed, which soon disappears, and, as no irritation results, consequently no appreciable pain is felt. Other similar bodies that are equally soluble in water act in the same manner, with the exception of the 39^ LOCAL ANESTHESIA. salts of the alkali and alkaline earth metals — ^as potassium or sodium bromid. The latter substances produce intense physical irritation, followed, however, by prolonged anesthesia, and in consequence are termed by Liebreich painful anesthetics. If, on the other hand, simple distilled water is injected, only a superficial anesthesia is produced; the injection itself is very painful, and acts as a direct protoplasm poison by maceration of the cell contents, which results in the death of the cell. If distilled water approximately at a ratio of ten drams to the pound of body weight is injected into dogs, they will succumb in a short time. The injection of higher concentrated salt solutions produces opposite efifects; water is removed from the tissues with more or less pronounced pain, and followed by superficial anesthesia. The red blood corpuscles are extremely susceptible to any injected fluid which is not isotonic in its nature. They are uni- versally destroyed ^hemolysis) by the injection of fluids which are not represented by an isotonic salt solution. Severe tissue disturbances result, which may terminate in necrosis. Hypotonic solutions — solutions containing less than 0.9 per cent of sodium chlorid — cause swelling of the tissue, while hypertonic solutions — solutions containing more than 0.9 per cent of sodium chlorid — ^produce shrinkage. These manifestations are proportionately the more intense the further the solution is removed from the freezing point of the blood. Furthermore, hypotonic as well as hypertonic solutions require much more time for their absorption than isotonic solutions, as the osmotic pressure has to be standardized to the surrounding fluids — that is, to the isotonic index of the tissue fluids. Local anemia, or ischemia — a temporary constriction of circulation — ^prevents, as it has been experimentally shown, the rapid absorption of fluids that are injected into the affected area. Retarded absorption of the injected fluid, holding poisonous drugs in solution, means increased action of these poisonous drugs within the injected area. Increased action denotes increased con- sumption of the poisoned drugs, and, as a consequence, there is less danger from general absorption. The more important means applied for the purpose of producing local anemia are: 1. The Esmarch elastic bandage. 2. The application of cold. 3. The extract of the suprarenal capsule, or its synthetic sub- stitutes. Some observers have maintained that local anemia produces anesthesia. This is not, however, the case, as it is merely an im- portant means to confine the injected anesthetic to the anemic region, LOCAL ANESTHESIA. 399 and thus bring about an increased and prolonged action of the drug. Consequently the concentration of the anesthetic solution may be of a lower percentage, which, of course, lessens the danger of intoxication. For plausible reasons the Esmarch elastic bandage cannot be made use of for dental operations. Physically reducing the temperature of the body by the applica- tion of cold (ice pack, ice and salt mixture, cold metals, etc.) was practised by the older surgeons. James Arnott, in 1848, suggested the adoption of diminished temperature as "a safer mode than any hitherto in use of producing insensibility in surgical operations," and Blundell, in 1855, advocated ice packs and salt solutions as means of producing "local anesthesia by congelation" for dental purposes. Through the efforts of Sir B, W. Richardson, in 1866, this method was placed on a rational basis by the introduction of his ether spray. To obtain good results, a pure ether (boiling point 95° C), free from water, is necessary. Certain other hydrocarbons possess similar prop- erties in varying degrees, depending on their individual boiling point. In 1867, Rottenstein called attention to the use of ethyl chlorid as a refrigerating agent, and Rhein, in 1889, introduced methyl chlorid for the same purpose. In 1891 Redard reintroduced ethyl chlorid as a local anesthetic, which since has become known by many trade names as antidolorine, kelene, narcotile, etc. — and mixtures of the first two in various proportions, known as anestol, anestile, coryl, methethyl, etc., are extensively used in minor oral and general surgery. A pure ethyl chlorid (boiling point 55° F., 13° C.) is best suited for this pur- pose, as it lowers the temperature of the tissues sufficiently to pro- duce a short superficial anesthesia in a few minutes. Too rapid cooling or prolonged freezing by methyl chlorid (boiling point 12° F., 24° C), or the various mixtures thereof, produce deeper anesthesia, but such procedures are dangerous. They frequently cut off circulation in the affected parts so completely as to produce sloughing (necrosis). Liquid nitrous oxid gas, hquid or solid car- bonic acid (recently known as carbonic acid snow), and liquid air, all of which have a boiling point far below zero, are recommended for similar purposes, but they require cumbersome apparatus and are extremely dangerous. Ethyl Chlorid and Its Administration. — Ethyl chlorid — ^Mono- chlore thane; hydrochloric ether, CaHgCl. "A haloid derivative, pre- pared by the action of hydrochloric acid gas on absolute alcohol." At normal temperature, ethyl chlorid is a gas, and under a pressure of two atmospheres it condenses to a colorless, mobile, very volatile 400 LOCAL ANESTHESIA. liquid, having a characteristic, rather agreeable, odor and burning taste. It boils at about 55° F. (13° C.) and is very inflammable, burning with a smoky, green-edged flame. It is stored in sealed glass or metal tubes, and when liberated at ordinary room tempera- ture (70° F., 21° C.) it evaporates at once. In commerce it is sup- plied in plain or graduated glass tubes of from 3 to 60 grams ca- pacity, or stored in metallic cylinders holding from 60 to 100 grams or more. To remove the ethyl chlorid from the hermetically sealed smaller tubes, the neck has to be broken off, while the larger glass and metallic tubes are provided with suitable stoppers of various designs to allow definite amounts of the liquid to be released. Mode of application. For the extraction of teeth, immediate re- moval of the pulp, opening of abscesses, and other minor opera- tions about the oral cavity, the tube should be warmed to body tem- perature, by placing it in heated water, and its capillary end should be held about six to ten inches from the field of operations. The distance depends on the size of the orifice of the nozzle, and complete va'porization should always be produced. The Gebauer tube is fitted with a spray nozzle, which shortens the distance to one or two inches, and is especially well adapted for dental purposes. The stream is directed upon the tissues until the latter are covered with ice crystals and have turned white. For the extraction of teeth the liquid should be projected directly upon the surface of the gum as near the apex of the root as possible, but care should be taken to protect the crown of the tooth on account of the painful action of cold on this part. Tissues to be anesthetized should first be dried and well sur- rounded by a film of vaselin or glycerin, and protected by cotton rolls and napkins, to prevent the liquid from running into the throat. Let the patient breathe through the nose. Occasionally light forms of general anesthesia are induced by inhaling the vapor. On account of the difficulty of directing the stream of ethyl chlorid upon the tissues in the posterior part of the mouth, it is not successfully applied in those regions. The intense pain produced by the extreme cold prohibits its use in pulpitus and acute pericementitis. To anesthetize the second and third branch of the fifth nerve, it is recommended to direct the stream of ethyl chlorid upon the cheek in front of the tragus of the ear, but the author has not seen good results from such a procedure. Cau- tion should be exercised in using ethyl chlorid near an open flame or in conjunction with the thermocautery, as severe burns have re- sulted by setting the inflammable vapor on fire. Within the last decade the active principle of the suprarenal cap- LOCAL ANESTHESIA, 40I sule has evoked extensive comments in therapeutic literature. It has been isolated by a number of investigators under different names, as epinephrin by Abel (1897), suprarenin by Fuerth (1898), and adrenalin by Takamine and Aldrich (1901). Many other titles are given to this chemical — as adnephrin, adrin, paranephrin, su- prarenalin, supracapsulin, hemostasin, etc. The United States Pharmacopoeia (eighth revision) has not as yet admitted this alka- loid to its pages, and, therefore, whenever we refer here to the hydro- chloric salt of the alkaloid of the suprarenal capsule, we speak of it as adrenalin, the term which is at present preferred in the United States. Adrenalin is a grayish-white powder, slightly alkaline in reaction, and perfectly stable in dry form. It is sparingly soluble in cold and more soluble in hot water, is insoluble in ether or alcohol, with acids it readily forms soluble salts. The preparation that is employed mostly for therapeutic purposes is a solution of adrenalin hydrochlorid in a i to 1000 physiologic salt solution, to which pre- servatives — as small quantities of chloretone, thymol, etc. — are added. Adrenalin solution does not keep well. On exposure to air, and espe- cially in the presence of even minute quantities of an alkaH, it is easily oxidized, becoming pink, then red, and, finally, brown, and with this change of color its physiologic property is destroyed. If the adrenalin solution be further diluted, it becomes practically worthless within a few days. When adrenalin is injected into the tissues, even in extremely small doses, it temporarily raises the arterial blood pressure, acting as a powerful vasoconstrictor by stimulating the smooth muscular coat of the blood vessels, and thus produces local anemia. Large doses finally reduce the blood pressure, and heart failure results. The respiration at first quickly increases, but slows down and, finally, stops with expiration. Its action is largely confined to the smooth muscle fibers of the peripheral vessels. Adrenalin is destroyed by the living tissue cells, the body ridding itself of the poison in some un- known manner. While adrenalin does not possess local anesthetic action, it increases very markedly the effect of certain anesthetics when combined with them. Very recently it has been shown by Esch that adrenalin possesses a specific action on nerve tissue, viz. : it prepares the latter tissue in a peculiar way, so as to take up the anesthetic more readily. Esch compares this action with the use of a mordant in the dyeing industry, viz.: to "fix" the color. These observations are of vast importance in connection with the production of local anesthesia. Carpenter, Peters, MoUer, and others referred to the use of adrenalin 26 402 LOCAL ANESTHESIA. in this respect, and, finally, Braun, in 1902, published his classic re- searches, and to him and his co-workers, especially Heinze and Lawen, belong the credit of establishing a rational basis for the production of local anesthesia. It is claimed that secondary hemorrhage frequently occurs after the anemia produced by the adrenalin has subsided, and that tissues themselves suffer from the poisoning effect of the drugs, resulting in necrosis. Such results are produced only by the injec- tion of too large quantities of the drug, which by their deeper action close up the blood vessels, and, if the tissues are too long deprived of the circulation, we are able to understand why sloughing may result. Small doses of adrenalin have no effect upon the tissues or on the healing of a wound. Palpitation of the heart and muscular tremor, which were occasionally noticed in the early period of the use of the drug, are the direct result of too large doses. Recently a synthetic adrenalin has been successfully prepared by Stolz, which, with hydrochloric acid, forms a stable and readily soluble salt. It is known as synthetic suprarenin hydrochlorid. The new chemical has been carefully tested physiologically and in clinical work, and the general consensus of opinion points to the fact that it is not alone equal, but in certain respects superior, to the organo-preparations. Syn- thetic suprarenin solutions may be readily sterilized by boiling. They are relatively stable, and their chemic purity insures uniform results. They are comparatively free from dangerous side actions. The writer's observations regarding the value of synthetic suprarenin relative to its actions and its general behavior is in full accordance with the above statements, and its advantages over the organo-preparations has led us to adapt it as a component in the preparation of local anes- thetic solutions. For dental purposes — that is, for injecting into the gum tissue — the dose may be hmited to one drop of the adrenalin solution (i to 1000) or the synthetic suprarenin solution (i to 1000), added to each cubic centimeter of the anesthetic solution, five drops being approximately the maximum dose to be injected at one time. Cocain Hydrochlorid. — It is the principal alkaloid obtained from cocoa leaves (erythroxylon coca) a large shrub indigenous to tropical South America. It appears in colorless crystals, flaky, lustrous leaflets or white powder; it is odorless, has a saline, slightly bitter taste and produces when placed upon the tongue a tingling sensation fol- lowed by numbness. At ordinary temperature it is soluble in about one-half part of water, about three parts of alcohol and glycerin, also soluble in chloroform, ether and olive oil. Its aqueous solution is neutral to litmus paper. Prolonged heating of the salt or its solution LOCAL ANESTHESIA. 403 produces decomposition of the chemical into methyl alcohol, benzoic acid and ecgonin. Solutions of cocain are unstable, they should preferably always be made fresh when wanted. Cocain hydrochlorid is incompatible with alkali hydrates or carbonates, salicylates, ben- zoates, bromids, and iodids, the mercury salts and silver nitrate. As early as i860, Niemann noted the fact that cocain when appHed to the tongue produced local anesthesia; later investigations, especially those of Von Anrep (1879) were not fully appreciated until Carl Koller, of Vienna, later of New York, brought it before the medical profession in a paper read before the Congress of Ophthalmologists at Heidelberg in 1884. Cocain is a general protoplasmic poison, possessing a selective power for the sensory nerve elements. It paralyzes the nerve cells, fibers and endings and produces vaso-con- striction at the place of its application. The respiration is at first accelerated, later it diminishes; respiratory paralysis is the usual cause of death. The pulse is quickened, later it is slow and weak; at first, the blood pressure rises, then falls and collapse results. Local anes- thesia, according to Preyer's conception, is produced as follows: Cocain possesses a definite affinity for the living protoplasm of the nerve cell; it enters with it into a labile union, thus producing local anesthesia, which lasts until this temporary union is broken up by releasing the chemical, not as the original cocain, however, but as an inert compound of a simpler structure. In other words, the living tissues rid themselves of the poison in some unknown manner. In dead tissue, the injected cocain will suffer no change whatsoever. No direct antidotes of cocain are known, consequently the treat- ment of general intoxication is purely symptomatic. Recumbent position of the body and inhalation of a few drops of amyl nitrite are the first important steps in dealing with collapse, which should be followed in severe cases with an injection of strychnin sulphate, 1-30 of a grain, together with artificial respiration. The relative toxicity of a given quantity of cocain solution depends upon the concentration of the solution. Reclus and others have clearly demonstrated that a fixed quantity of cocain in a 5 per cent or 10 per cent solution is almost equally as poisonous as five times of the same quantity in a 1-5 per cent solution. From the extensive literature on the subject, we are safe in fixing the strength of the solution for dental purposes at i per cent. This quantity of cocain raises the freezing point of distilled water just a little above 0.1° C. To obtain an isotonic solution corresponding to the freezing point of the blood, 0.8 per cent of sodium chlorid must be added. Having just 404 LOCAL ANESTHESIA. prepared a cocain solution which is equal to the blood in its osmotic pressure upon the cell wall, it is now necessary to aid the slightly vaso- constrictor power of the drug by the addition of a moderate quantity of adrenalin. As stated above, one drop of adrenalin added to 2 c.c. of the isotonic cocain solution is sufficient to produce the desired effect. A suitable solution for dental purposes may be prepared as follows : Cocain hydrochloric! S grains Sodium chlorid 4 grains Sterile water i fluid ounce To each syringeful (30 minims) add one drop of adrenalin chlorid solution, when used. Ever since the introduction of cocain into materia medica for the purpose of producing local anesthesia, quite a number of sub- stitutes have been placed before the profession, for which superiority in one respect or another is claimed over the original cocain. The more prominent members of this group are tropacocain, the eucains, acoin, nirvanin, alypin, stovain, novocain, and, very recently, quinin and urea hydrochlorid. None of these compounds, with the exception of novocain has proved satisfactory for the purpose in view. The classical researches of Braun have established certain factors which are imperative to the value of a local anesthetic. These factors con- cern their relationship to the tissues in regard to their toxicity, irrita- tion, solubility and penetration, and to the toleration of adrenalin. There is no need at this moment to enter into a discussion of the pharmacologic action of the drugs usually classified as local anes- thetics. Let it suffice to state how the above-mentioned drugs fulfil the demands of Braun. Tropacocain is less poisonous, but also less active than cocain, it completely destroys the action of adrenalin; the eucains partially destroy the adrenalin action, they are, comparatively speaking, equally as poisonous as cocain; acoin is irritating to the tissues and more poisonous than cocain; nirvanin possesses little anesthetic value; alypin and stovain are closely related, producing severe pain when injected, which occasionally has resulted in necrosis. Quinin and urea hydrochlorid reacts strongly acid and, as a con- sequence, severely damages the tissues in the injected area. As we have recently shown elsewhere it possesses no advantage when employed as a local anesthetic in dental operations but has many disadvantages as compared to cocain or novocain. Novocain alone fully corresponds to every one of the above claims. Its toxicity is about two to six times less than cocain; it does not irritate in the slightest degree when injected, consequently no pain is felt LOCAL ANESTHESIA. 405 from its injection per se; it is soluble in its own weight of water; it will combine with adrenalin in any proportion without interfering with the physiologic action of the latter, and it will be readily ab- sorbed by the mucous membrane. The studies of Biberfield and Braun brought to light another extremely interesting factor concerning the novocain-adrenalin combination. Both experimenters, working in- dependently of each other, observed that the adrenalin anemia on the one hand, and the novocain anesthesia on the other hand were markedly increased in their total effects upon the tissues. Consequently, a small quantity of this most happy combination is required to produce the same therapeutic effect as a large dose of each individual drug alone would produce when injected separately. The injection of a solution of the combined drugs is precisely confined to the injected area; general effects are, therefore, rarely produced. Novocain is the hydrochloric salt of a synthetically prepared alkaloid, the methyl ester of p-aminobenzoic acid. It is a white crystalline powder, or colorless needle-shaped crystals, melting at 263° F. (156° C). It may be heated to 200° F. (120° C.) without decomposition. It dissolves in an equal amount of cold water, the solution having a neutral character; in cold alcohol it dissolves in the proportion of i to 30. Caustic alkalies and alkaline carbonates pre- cipitate the free base from the aqueous solution in the form of a color- less oil, which soon solidifies. It is incompatible with the alkalies and alkaline carbonates, with picric acid, and the iodids. Its solu- tions may be sterilized by boiling without decomposition. As stated above, the relative toxicity of a given quantity of cocain in solution depends upon its concentration, this same peculiarity is not shared by novocain. The dose of novocain may be safely fixed at one-third of a grain for a single injection. For dental pur- poses a one and one-half or a two per cent solution in combination with adrenalin has been injected without any ill results. For the pur- pose of confining the injected novocain to a given area, the addition of adrenalin in small doses, on account of its powerful vasoconstrictor action, is well adapted. It is the important factor which prevents the ready absorption of both drugs and consequently largely nullifies poisonous results. An injection of ten drops of a two per cent solu- tion of novocain labially into the tissue produces a diffuse anesthesia lasting approximately twenty minutes; the same quantity, with the addi- tion of one drop of adrenalin chlorid solution increases the anesthetic period to over one hour, and localizes the effect upon the injected area. 4o6 LOCAL ANESTHESIA. A suitable solution of novocain for dental purposes may be pre- pared as follows: Novocain lo grains Sodium chlorid 4 grains Distilled water i fluid ounce Boil. To each syringeful (2 c.c.) add two drops adrenalin chlorid solu- tion when used. A sterile solution may be made extemporaneously by dissolving the necessary amount of novocain-adrenalin in tablet form in a given quantity of boiled distilled water. A suitable tablet may be prepared as follows: Novocain 1-3 grain Synthetic suprarenin hydrochlorid 1-1200 grain Sodium chlorid 1-3 grain One tablet dissolved in twenty minims of sterile water makes a two per cent solution of novocain ready for immediate use. Solutions for hypodermic purposes should preferably be made fresh when needed. A small glass dish and a dropping bottle con- stitute the simple outfit for such work. The dropping bottle should hold from one to two ounces. A suitable one is made by the Whitall- Tatum Co., of Philadelphia, and may be bought in the drug shops. It should be provided with a dust cap. "A groove on one side of the neck of the bottle, and a vent on the other, connected with two grooves in the back of the stopper, allow the contents to flow out drop by drop. A quarter turn of the bottle closes the bottle tightly." The water used for making the solution should be boiled and filtered distilled water. The hypodermic solution can be made extemporaneously in a few sec- onds; place a tablet in a sterile glass dish, add 20 minims (i c.c.) of water, and to facilitate the solution, mash the tablet. The solution is now ready for immediate use. The Hypodermic Armamentarium. — A hypodermic syringe that answers all dental purposes equally well is an important factor in carrying out the correct technique of the injection. The injection into the dense gum tissue requires from 15 to 50, or even more, pounds of pressure as registered by an interposed dynamometer, while in pressure anesthesia 100 or more pounds are frequently applied. The selection of a suitable hypodermic syringe is largely a matter of choice. All-glass syringes, glass barrel syringes, and all-metal syringes are the usual types found in the depots. After testing most LOCAL ANESTHESIA. 407 of the dental hypodermic syringes offered in the dental depots within the last five years by means of the pressure gauge and in clinical work, subjecting the syringes to a routine wear and tear, the author has found that the all-metal syringes of the "imperial" types are to be preferred over other makes. They are usually made of nickel-plated brass, which, however, is a disadvantage, as the nickel readily wears off from the piston, and exposes the easily corroded brass. The Manhattan all- metal platinoid syringe gives the best general service, and we can conscientiously recommend it to our confreres. The syringe holds 40 minims (2 c.c), is provided with a strong finger cross-bar and is ex- tremely simple in construction. The piston consists of a plain metal rod, without a thickened or ground piston-end or packing. The piston-rod is sufficiently long to allow about two inches of space between the cross- bar and the piston-top. This space is of importance, as it allows the last drop of the fluid to be expelled under heavy pressure without tiring the fingers. The packing consists of leather washers inserted at the screw point, and are quickly removed and replaced if necessary. The hypodermic syringe requires careful attention. It is not necessary to sterilize it by boiling after each use, unless it be con- taminated with blood or pus. The simple repeated washings with alcohol and carefully drying is sufficient. The cap is readjusted, and the piston-rod is covered with a thin film of carbonated vase- lin, or surgical lubricating jelly, and placed in position. If the syringe is boiled, all the washers must be removed. The syringe is kept in a covered glass or metal case, and a large bacteriologic Petri dish is suitable for this purpose. Leather-lined or felt-lined boxes afford breeding places for bacteria. Some operators prefer to constantly keep their syringes in an antiseptic solution when not in use, and others prefer to place them in a special sterilizing bottle, which bottles may now be purchased at dental depots. Dental hypodermic needles should be made preferably of seam- less steel, or, still better, of nickel steel, 26 to 28 B. & S. gauge, and provided with a short razor edge point. Thicker needles cause un- necessary pain, and thinner needles are liable to break. Iridio- platinum needles are preferried by some operators, as they may be readily sterilized in an open flame. The needle should measure from a quarter to half an inch. For infiltration anesthesia one-inch needles are necessary, and curved needles of various shapes are essen- tial in reaching the posterior part of the mouth. The "Schimmel" needles are excellent, but do not, however, fit every syringe. For pressure anesthesia special needles are required, and may be bought 408 LOCAL ANESTHESL\. at the depots, or quickly prepared by grinding off the steel needle at its point of reinforcement. The sterile needles should be kept in well- protected glass containers. The needles are sterilized after each use by boiling in plain water, dried with the hot-air syringe, and immedi- ately transferred to a covered sterile glass dish. The sterile needles should not be again touched with the fingers, and the customary wire insertion is unnecessary. Technique of Injection. — Various methods of injecting the anes- thetic solution about the teeth are in vogue. For the sake of con- venience we may be permitted to divide them as follows : The subperiosteal injection. The peridental injection. The intraosseous injection. The perineurial injection. The injection into the pulp. Before starting any surgical interference in the mouth, the field of operation should be thoroughly cleansed with an antiseptic solu- tion. A thin coat of the official tincture of iodin painted over the surface is very useful for this purpose. After the diagnosis is made the method of injection best suited for the case on hand is then decided. The necessary quantity and the concentration of the anesthetic solu- tion is now prepared, and the syringe and hypodermic needle fitted ready for the work. To facilitate the ready penetration of the needle into the tissues, its point may be coated with carbolated vaselin. The correct position of the syringe in the hands of the operator and its proper manipulation is an important factor, and has to be acquired by practice. The hand holding the syringe is exclusively governed in its movements by the wrist, so as to allow delicate and steady move- ments, and the fingers must be trained to a highly developed sense of touch. The syringe is filled by drawing the solution up into it; it is held perpendicularly, point up, and the piston is pushed until the first drop appears at the needle point, which precaution prevents the in- jection of air into the tissues. The Subperiosteal Injection. — The subperiosteal injection about the root of an anterior tooth is best started by inserting the needle midway between the gingival margin and the approximate location of the apex. The pain of the first puncture may be obviated by a fine, very sharp pointed needle, the simple compression of the gum tissue with the finger tip, by holding a pledget of cotton saturated with the prepared anes- thetic solution on the gum tissue for a few moments, or by applying a very small drop of liquid phenol on the point of puncture. The LOCAL ANESTHESIA. 409 needle opening faces the bone, the S}Tinge is held in the right hand, at an acute angle with the long axis of the tooth, while the left hand holds the lip and cheek out of the way. After puncturing the mucosa, a drop of the liquid is at once deposited in the tissue, and the further injection is painless. Slowly and steadily the needle is forced through the gum tissue and periosteum along the alveolar bone toward the apex of the tooth, depositing the liquid under pressure close to the bone on its upward and return trip. The continuous slow moving of the needle prevents injecting into a vein. A second injection may be made by partially withdrawing the needle from the puncture and swinging the syringe anteriorly or posteriorly, as the case may be, from the first route of the injection. This latter method is especially indicated in injecting the upper molars. After removing the needle, place the finger tip over the puncture and slightly massage the injected area. A circular elevation outlines the injected field. The naturally pink color of the gum will shortly change to a white anemic hue, indi- cating the physiologic action of the adrenalin on the circulation. No wheal should be raised by the fluid, as that would indicate super- ficial infiltration and consequently failure of the anesthetic. As the hquid requires a definite length of time to pass through the bone lamina and to reach the nerv^es of the peridental membrane and the pulp, from five to ten minutes should be allowed before the extraction is started. The length of time depends on the density of the surrounding structure of the tooth. The progress of the anes- thesia may be tested with a fine pointed probe, and its completeness indicates the time when the extraction should be started. The upper eight anterior teeth usually require a labial injection only, while the molars require both a buccal and a palatine injection, using a slightly curved needle for this purpose. Buccally the injec- tion is made midway between the mesial and distal root, and on the palatine side over the palatine root. The lower eight anterior teeth are comparatively easily reached by the injection. The straight needle is inserted near the apex of the tooth, the syringe is held in a more horizontal position and the injection proceeds now as outlined above. The lower molars require a buccal and lingual injection. The curved needle is inserted midway between the roots, the gum margin, and the apices. The external and internal oblique lines materially hinder the ready penetration of the injected fluid, and therefore ample time should be allowed for its absorption. If two or more adjacent teeth are to be removed, the injection 4IO LOCAL ANESTHESIA. by means of infiltrating the area of the gum fold directly over the apices of the teeth is to be preferred. It is advisable to use a one-inch needle for this purpose, holding the syringe in a horizontal position, so as to reach a larger field with a single injection. The injection into inflamed tissue, into an abscess, and into phleg- monous infiltration about the teeth is to be avoided. The injection into engorged tissue is very painful; the dilated vessels quickly absorb cocain without producing a complete anesthesia, and generally poison- ing may be the result. In purulent conditions the injection is decidedly dangerous, as it forces the infection beyond the line of demarcation. If the abscess presents a definite outline, the injection has to be made into the sound tissue surrounding the focus of infiltration. If a tooth is affected with acute diffuse or purulent pericementitis, a distal and a mesial injection usually produce successful anesthesia by blocking the sensory nerve fibers in all directions. Peridental Anesthesia. — The teeth or roots standing singly, or teeth affected by pyorrhea or similar chronic peridental disturbances, are frequently quickly and satisfactorily anesthetized by injecting the fluid directly into the peridental membrane. This method is known as peridental anesthesia, and its technique is very simple. In single- rooted teeth a fine and short hypodermic needle is inserted under the free margin of the gum or through the interdental papilla, into the peridental membrane between the tooth and the alveolar wall. Some- times the needle may be forced through the thin alveolar bone so as to reach the peridental membrane direct. To gain access to this mem- brane in teeth set close together, separation is essential. It may be accomplished with an orange wood stick or by any of the various mechanical separators. By so doing, the body of the tooth is shifted to one side and thereby creating a slight space between it and the alveolar process. The injection is now made directly into the exposed peridental membrane. By reversing the separator, the tooth is shifted to the opposite side and the injected liquid is forced toward the apex of the tooth. A second injection is now made in this freshly exposed portion of the peridental membrane. Two, sometimes three, in- jections are necessary. To force the liquid into the membrane usu- ally requires a higher pressure than that which is necessary for inject- ing into the periosteum covering the alveolar process, but the quantity of the anesthetic fluid is less than that which is required for the former injection. Acute inflammatory conditions of the peridental membrane and its sequelae prohibit the use of this method. Peridental anes- thesia is the purest form of local anesthesia, since the seat of the LOCAL ANESTHESLA.. 41I nerve supply of the tooth is very quickly reached, and as a conse- quence the results obtained are in the majority of cases extremely satisfactory, provided that general conditions justify its applica- tion. The method is especially serviceable for the removal of pulps and in all cases where contact anesthesia is not indicated or for temporary desensitizing a tooth for operative procedures. Intraosseous Injection. — To facilitate the passage of the injected fluid into the bone structure proper, Otte, in 1896, recommended a method by which he forces the anesthetic solution directly into the spongy cancelloid bone. Otte terms this procedure the intraosseous method of injection, and its technique is described by him as follows: After the gum tissue is thoroughly cleansed with an antiseptic solution, it is anesthetized about the neck of the tooth in the usual manner. After waiting two or three minutes, an opening is made into the gum tissue and the bone on the buccal side with a fine spear drill or a Gates- Glidden drill. The opening should be made more or less at a right angle with the long axis of the tooth, a little below the apical foramen in single-rooted teeth or between the bifurcation in the molars. The right- angle hand piece is preferably employed for this purpose. The drill should be of the same diameter as the hypodermic needle. The gum fold is tightly stretched to avoid laceration from the rapidly re- volving drill. As soon as the alveolar process is penetrated, a peculiar sensation conveyed to the guiding hand indicates that the alveolus proper is reached, and the sensation felt by the hand is about the same as that experienced when a burr enters into the pulp chamber. In this artificial canal the close fitting curved needle of the hypo- dermic syringe is nov/ inserted, and the injection is made in the ordi- nary way. The quantity of fluid used is much less than is usually needed for a subperiosteal injection. The roots of the teeth are im- bedded in a sieve-like mass of bone tissue (diploe), which allows a ready penetration of fluid when injected under pressure. Very re- cently, Masselink advocates this method of the anesthetization of any tooth in the mouth either for the purpose of extracting or the removal of its pulp. He employs a No. 1/2 round burr for penetrating the alveolar plate and a very short needle (about 1/16 of an inch) with a dull point for the injection. Perineiirial Injection. — For the anesthetization of a number of teeth in the upper or the lower jaw, conductive anesthesia by means of perineurial injection is preferably employed. The perineuria! injection is made near the point of exit or entrance of the various nerves about their respective foramina. To anesthetize all the teeth 412 LOCAL ANESTHESIA. of one-half of the upper jaw four injections are necessary, i. e., two buccally and two on the palatine side of the bone. A one-inch needle is required for such work. To reach the many small branches of the posterior dental nerves at the alveolar foramina the injection is made buccally over the region of the tuberosity about one half inch above the gingival line between the first and second molar tooth. The second injection is made below the infraorbital foramen, so as to reach the middle and anterior dental nen^es. With the index finger of the left hand the foramen is approximately located by exerting pressure upon the nerve-exit. The lip is lifted up with the middle finger of the same hand and the needle is now inserted between the apices of the cuspid and first bicuspid teeth. The needle is slowly pushed forward until its point is felt beneath the finger tip. To reach the nerve supply of the hard palate one injection is made near the posterior palatine canal, and the other near the foramina of Scarpa. The great palatine nerves pass through the posterior palatine canals on either side of the hard palate. The canals lie about three-eighths of an inch above the edge of the alveolar process and the last molar tooth. They move posteriorly with the eruption of the successive teeth. The naso-palatine nerves pass through the foramina of Scarpa (incisive foramen) which are situated in the line of the suture of the maxillary bones. If an imagi- nary line is drawn from the distal borders of the two cuspids and passing over the hard palate, the line will ordinarily pass through the foramina. The needle should be inserted directly back of the papilla, which lies posteriorly between the central incisor teeth. To anesthetize one-half of the mandible, three injections for the deposition of the anesthetic solution are necessary. The first injection is applied near the mandibular foramen, the second near the mental foramen, and the third into the incisive fossa. To locate the mandibular foramen in the mouth, the lingual surface of the ramus is palpated with the finger, the anterior sharp border of the coronoid process is easily felt about five-eighths of an inch posterior of the third molar. The process passes downward and backward of the third molar, and enters into the external oblique line. Mesially from this ridge is to be found a small triangular concave plateau, which is facing downward and outward, being bound mesially by a distinct bony ridge and covered with mucous membrane. As there is no anatomical name attached to this space, Braun has called it the re- tro molar triangle (trigonum retromolare). In the closed mouth it is located at the side of the upper third molar, and in the open mouth it is found midway between the upper and lower teeth. Immediately LOCAL ANESTHESIA. 413 back of the mesial border of this triangle, directly beneath the mucous membrane, lies the lingual nerve, and about three-eighths of an inch farther back the mandibular nerve is to be found. This last nerve lies close to the bone, and enters into the mandibular foramen, which is partly covered by the mandibular spine. Before starting the injection the patient should be cautioned to rest his head quietly on the headrest of the chair, as any sudden move- ment or interference with the hand of the operator may be the cause of breaking the needle in the tissue. The syringe, provided with a one-inch needle, is held in a horizontal position, resting on the occlud- ing surfaces of the teeth from the cuspid backward and slightly toward the median line. The needle is to be inserted three-eighths of an inch above and the same distance back of the occluding surface of the third lower molar, the needle opening facing the bone. This position will insure the correct direction of the needle point so as to reach the tissues immediately surrounding the nerves, and not lose the injection in the adjacent thick muscle tissue. The needle must always be in close touch with the bone, and is now slowly pushed forward, depositing a few drops of fluid on its way until the ridge is reached. About five drops of fluid are injected in this immediate neighborhood for the purpose of anes- thetizing the lingual nerve. The needle is pushed very slowly forward, always keeping in close touch with the bone and depositing fluid on its way, until it is pushed in about five-eighths of an inch. It is impor- tant carefully to feel the way along the bony wall of the ramus as the needle may have to pass over the roughened and bony elevations, which afford attachment to the internal pterygoid muscle. During the injection the syringe should remain in the same horizontal posi- tion as heretofore outlined. Soon after the injection, paresthesia of one-half of the tongue on the side of the injection occurs, which is soon followed by anesthesia of the mandibular nerve. Paresthesia of the mucous membrane and half of the lower lip is also estabhshed. The pulps of the lower teeth, including the cuspid and lateral incisor and the gum tissue on both sides of the jaw, are anesthetized, including a part of the anterior floor of the mouth. The complete anesthesia of the two nerves also anesthetizes the whole alveolar process in this region. About five minutes are required for the complete anesthe- tization of the lingual nerve, and at least fifteen minutes for the man- dibular nerve. Braun claims that the injection is absolutely free from danger, while Romer states that danger may arise if the whole quantity of the solution should accidentally be injected into a vein. The mental foramen lies midway between the superior and in- 414 LOCAL ANESTHESIA. ferior border of the body of the mandible on its external surface, usually below the second bicuspid teeth. Its opening always faces posteriorly. An injection near this point increases the anesthesia in the bicuspid region. The incisive fossa is a shallow depression on the external surface of the mandible between the cuspid teeth. It may be located by the palpating finger immediately above the chin. A number of small foramina are found in this region for the passage of nerves and nutrient vessels. The lower incisors may be anes- thetized by making injections anteriorly into the incisive fossa and one posteriorly in the region corresponding to the fossa. Usually, peridental anesthesia is to be preferred for these teeth. Conductive anesthesia is serviceable if a number of teeth have to be removed at one visit. It should be borne in mind, however, that in average only one-half of either jaw should be anesthetized at one sitting so as to keep the quantity of the injected anesthetic solution within the limits of ordinary dosage. The Injection into the Pulp. — By pressure anesthesia, pressure cataphoresis, or contact anesthesia, as the process is variously termed, we understand the introduction of a local anesthetizing agent in solu- tion by mechanical means through the dentin into the pulp for the purpose of rendering this latter organ insensible to pain. Simple hand pressure with a suitable instrument, the hypodermic syringe or the so-called high pressure syringe, is recommended for such pur- poses. Regarding the principles of pressure anesthesia, it should be remembered that we cannot force a liquid through healthy dentin by a mechanical device without injury to the tooth itself. If a cocain solution is held in close contact with the protoplasmic fibers of the dentin, the absorption of cocain takes place in accordance with the law of osmosis. The imbibition of the anesthetic is enhanced by em- ploying a physiological salt solution as a vehicle. On the other hand, living protoplasm reacts unfavorably against the ready absorption of substances by osmosis for two reasons: (i) Its albumin molecule is relatively large and not easily diffusible, and (2) as an integral part of its life it possesses "vital" resistance toward foreign bodies. These latter factors are sufficiently demonstrated by the fact that it is very difficult to strain living tissue. Dehydration of the protoplasm in- creases the endosmosis of the anesthetic solution markedly. When we apply the same "pressure" anesthesia upon carious dentin, the above statements do not hold good. We are able to press fluids quite readily through carious dentin. We must bear in mind that such dentin has been largely deprived of its inorganic salts, leaving LOCAL ANESTHESIA. 415 an elastic spongy matrix in position. By drying out this dentin and then confining the anesthetic solution under a suitable water-tight cover, the pressure applied by the finger is quite sufficient to obtain the results. Colored fluids may be readily pressed through such dentin and even stain the pulp. In teeth not fully calcified and in so-called soft teeth, pressure anesthesia is more readily obtained while, according to Zederbaum, the process fails in "teeth of old persons, teeth of inveterate tobacco chewers, worn, abraded and eroded teeth, teeth with extensive second- ary calcific deposits, teeth whose pulp canals are obstructed by pulp nodules, teeth with metallic oxides in tubules, teeth with leaky old fillings, badly calcified teeth — ^mainly all from one and the same cause, namely, clogged tubuh. In most cases no amount of persistent pres- sure will prove successful." From the foregoing it will be observed that the so-called high pressure syringes possess little merit relative to pressure anesthesia. The pressure which can be produced by a good working all-metal syringe, holding it between the index and middle fingers and forcing the piston with the thumb, amounts to 250 to 300 pounds in the average man. The pressure required in pressure anesthesia to produce a perfect contact is usually much less than the above force. Methods of Anesthetizing the Pulp. — i. The pulp is wholly or par- tially exposed. Isolate the tooth with the rubber dam and clean it with water and alcohol. Excavate the cavity as much as possible and if the pulp is not exposed, dehydrate with alcohol and hot air. Saturate a pledget of cotton or a piece of spunk with a concentrated cocain or novocain solution, place it into the prepared cavity and cover it with a piece of vulcanizable rubber and with a suitable bur- nisher apply slowly, increasing continuous pressure from one to three minutes. The pulp may now be exposed and tested. If it is still sensitive, repeat the process. Loeffler states that " this pressure may be applied by taking a short piece of orange wood, fit it into the cavity as prepared, and direct the patient to bite down upon this with in- creasing force. In this way we can obtain a well-directed regulated force or pressure, and with less discomfort to the patient and operator." Miller described this process as follows: "After excavating the cavity as far as convenient and smoothing the borders of it, take an impression in modeling compound, endeavoring to get the margins of the cavity fairly well brought out; put a few threads of cotton into the cavity and saturate them thoroughly with a 5 to 10 per cent solu- tion of cocain, cover this with a small bit of rubber dam, and then 4l6 LOCAL ANESTHESIA. press the compound impression down upon it. We obtain thereby a perfect closure of the margin, so that the liquid cannot escape and one can then exert pressure with the thumb sufl&cient to press the solution into the dentin. 2. The pulp is covered with a thick layer of healthy dentin. With a very small spade drill bore through the enamel or direct into the dentin at a most convenient place, guiding the drill in the direction of the pulp chamber. Blow out the chips, dehydrate with alcohol and hot air, and apply the syringe provided with a special needle, making as nearly as possible a water-tight point. Apply slow, continuous pressure for two or three minutes. With a round burr the pulp should now be exposed, and if still found sensitive, the process is to be repeated. Recently a method has come into vogue which allows successful anesthetization of the pulp by injecting the anesthetic solution around the apex of the tooth. The spongy alveolar process, which contains lymph channels, allows the ready penetration of the fluid. The injection should be made close to the bone, pushing the needle slowly toward the apex, while the fluid is deposited drop by drop. No wheal should be raised by the injection, otherwise the benefits of the pressure from the dense gum tissue is lost. According to Hertwig, the protoplasm of the cell primarily transfers irritation; and, secondly, transmits absorbed materials. Therefore, the anesthetic solution has to pass through the entire dentinal fiber because the nerve tissue of the pulp proper is reached. Consequently a certain period of time is required before the physiological effect of the anesthetic is manifested. This period of latency is dependent upon the thickness of the intermediate layer of dentin or bone. The successful anesthetization of the pulp depends largely upon this most important factor of allowing sufl&cient time for the proper migration and action of the drug. The anesthetizing of the peridental membrane for the treatment of pyorrhea alveolaris is a comparatively simple matter if carried out according to the methods as outlined under the heading of peridental anesthesia. Sometimes a topical application of a fairly concentrated novocain-adrenalin solution (about lo per cent) and applied to the pockets by means of cotton ropes accomplishes the desired purpose. The surgical treatment of pyorrhea is materially simplified if the tissues under consideration are relieved of sensation. Local anesthesia for operations about the mouth, exclusive of the extraction of teeth. In operating about the mouth for an abscess, a cystic or a solid LOCAL ANESTHESIA. 417 tumor of the approximate size of a large walnut, a malposed tooth, or for any other purpose, the rhomboid infiltration according to Hackeilbruch affords the simplest means of producing a most satis- factory anesthesia. After previously cleansing the field of operation with an antiseptic solution, a very small drop of phenol is placed at A and B to superficially obtund the point of puncture. The needle is quickly thrust through the mucosa at A, and at once slow pres- sure is exerted on the piston, moving the needle steadily along the external line of the tumor. The needle is now partially withdrawn, without, however, leaving the original puncture, and a second injec- tion or as many as may be needed are made in opposite directions. This maneuver is now repeated at B and thus a circumscribed infil- tration of the whole tumor is obtained. If the tumor, etc., is very large, additional punctures and injections may be made as outlined in the schematic drawing. After ten to fifteen minutes' waiting the extirpation of the tumor may be begun. For injecting the soft tis- sues other than the gum a i per cent novocain — adrenalin solution — one tablet dissolved in 2 c.c. of water — ^is quite sufficient. The anesthetization of the soft and hard palate is comparatively easily accomplished. The injection on the hard palate is started at the gingival edge of the alveolar periosteum on both sides of the jaw toward the median line. As the gum tissue is extremely dense, great force is required for a complete infiltration in this region, and only small quantities of the solution are required. The soft palate is easily infiltrated by inserting the curved needle posteriorly to the third molar. Small tumors and cysts on the tongue or the floor of the mouth are best anesthetized by the rhomboid infiltration of Hackenbruch. For the complete extirpation of a ranula, the injection is made into the cyst wall near the periphery, after which the cyst is slit open and a small quantity of the anesthetic solution is injected into the inner surface of the cyst. Large cysts, tumors and major operations on the tongue require the anesthetization of both lingual nerves. In injecting and operating on the floor of the mouth, the index finger of the left hand should be placed on its external surface as a guide to the needle or the knife. Local anesthesia is indicated in all minor and in relatively many major operations on the mucous surfaces, the skin, and the teeth. Local anesthesia is not a substitute for general anesthesia; its use- lessness is materially increased by familiarizing one's self with the modern methods of its production and with a perfect mastering of 4l8 LOCAL ANESTHESIA. the technique. The danger of poisoning has been practically elimi- nated by using isotonic solutions containing a relative small percent- age of the anesthetic in combination with the alkaloid of the supra- renal capsule. Even if the danger of general necrosis is small under the very best conditions, the danger from local anesthesia is always less. The greater majority of all dental operations can be safely carried out under local anesthesia, provided the operator has acquired a complete working knowledge of the various components which, as a whole, constitute this important branch of dental therapeutics. CHAPTER XXVI. THE EXTRACTION OF TEETH. BY FERDINAND J. S. GORGAS, A.M., M.D,, D. D. S. The extraction of teeth, although usually regarded as a minor surgical operation, is, nevertheless, an operation that frequently pre- sents great difficulties, and is, perhaps, more often performed than any other in surgery. To successfully extract teeth requires an accurate knowledge of the histology, anatomy, and physiology of these organs, and the structures in direct relationship with them. The anatomy referred to, denominated " dental anatomy," includes that part of the science of organic structure which relates to the bones of the head, especially the jaws; the origin and distribution of the vessels and nerves supplying the dental tissues with blood and sensation; also a knowl- edge of the muscles concerned in moving the lower jaw, as well as those which are instrumental in producing the varied facial expressions. As the teeth are of dermal origin — morphological appendages of the skin, and compared with such tissues as hair and nails — the origin and development of their hard structures, viz., enamel, dentin, and ceiAentum, should be well understood. The teeth, as before stated, being dermal appendages, are not a part of the osseous system, and the science of embryonic evolution teaches that they are inserted in sockets, as is common with all large teeth, and also that they have a strong attachment. In the human subject all the teeth are imbedded in well-developed alveolar cavities of the supe- rior and inferior maxillary bones, their function being to seize, bite, and masticate the food. The enamel is derived from the ectoderm, differing in this respect from bone, which is a product of the mesoderm. The enamel cover- ing the exposed portion, or crown, of the tooth, being its protective covering, is the hardest structure in the body, and is not, like bone, regenerated. Its structural elements are enamel rods or prisms, and interprismatic or cement substance, which holds the rods or prisms together. When fractured, the tissue separates along the cemental line — this is known as the cleavage of the enamel. The dentin is derived from the mesoderm, and constitutes the body of the tooth, determines its form, and is similar, in respect to its origin, 419 420 THE EXTRACTION OF TEETH. to bone. The structural elements of the dentin are minute canals — tubules, and intertubular sulpstance, the canals radiating from a central cavity which contains the pulp of the tooth. The cementum, which covers the root of the tooth and incloses the dentin, at the gingival border or neck of the tooth, slightly overlapping the enamel, is a variety of bone tissue, destitute, however, of the Haver- sian canals common to bone, but contains lacunae and canaliculi like bone. The cementum is composed of parallel lamellae of bone tissue, small vessels penetrating these thin plates, while other vessels, derived from the pulp, pass through the cementum in the opposite direction. Fibers from the investing membrane of the root of the tooth — peri- cemental membrane, and which resemble the fibers of Sharpey in bone — are firmly attached to the cementum, and furnish a medium of con- nection by which the tooth is securely held in its alveolar cavity; they also account for the resistance offered by the tooth to its forcible re- moval by the forceps. The pericemental membrane lines the alveolar cavity and surrounds the root of the tooth. Its cellular elements are fibroblasts, osteoblasts, osteoclasts, and epithelial cells, the latter being located between the fibers of the membrane. The fibers of the pericemental membrane, formed and renewed by the fibroblasts, extend into the cementum and have a transverse direc- tion, being attached at one extremity to the cementum of the root of the tooth, and at the other to the bony wall of the alveolar cavity. Resembling Sharpey's fibers of bone, these fibers of the pericemental membrane are white and inelastic, their function being to increase and renew the fibrous tissue of the membiane by which the toQth is sup- ported in place. This fibrous tissue consists of two varieties, one of which is coarse and radiating, and forms the bulk of the tissue, and by its strength firmly secures the tooth; the other variety is fine and interlaces with the coarse variety, being connected with the blood vessels permeating the tissue. From the gingival portion of the cementum, the fibers of the pericemental membrane pass horizontally, some of them connect- ing with the membrane of adjoining teeth, and others passing into the connective tissue of the adjacent mucous membrane, thus giving hard- ness to the gums. The pericemental membrane is richly supplied with blood, some of the vessels entering the membrane near the apex of the root, others from the Haversian canals, while a third supply is derived from the mucous membrane of the gum near the gingival border. THE EXTRACTION OF TEETH. 421 The teeth, being of dermal origin, are attached by insertion into well-developed cavities in the alveolar processes of the jaws, which are known as alveoli, and which are formed by the outer and inner plates of the alveolar process. The shape, size, and length of the roots of the teeth determine the shape, size and depth of the alveoli. (Fig. 283.) Each alveolus consists of compact bone tissue surrounded by cancellated or spongy tissue, which acts as a cushion against the shocks of mastication. The outer and inner plates of the alveolar process are connected by numerous septa which outline the shapes of the orifice of the cavities of the teeth. Dr. I. Norman Broomell, in his treatise on the "Anatomy and Histology of the Teeth," describes the alveoli as follows (Figs. 284, 285 and 286) : "The first socket, or that next to the mesial surface of the bone, gives support to the central incisor tooth. It forms almost a perfect cone, Fig. 283. and has an average depth of almost half an inch. Its lower border is circular, and the anterior or labial portion describes a larger circle than the posterior or palatal half. The mesial and distal walls are somewhat flattened. The second cavity proceeding backward from the mesial line, supports the lateral incisor tooth. It is also conic, but much smaller than the preceding. It is seldom over | to j\ of an inch in depth. It is much flattened on its mesial and distal walls, giving the appearance of an oblong, rather than a round cavity. This socket, as well as that for the central incisor, occupies an almost vertical position in the process. Very frequently the socket for the lateral incisor presents a slight distal curve at its upper extremity. The third socket, or that giving support to the cuspid tooth, is much larger and deeper than those previously described. It extends upward, inward, and backward, to the average depth of f to f of an inch. In transverse section, its labial wall presents a much larger circle than its palatal 422 THE EXTRACTION OF TEETH. margin. The labial and distal walls are much flattened and some- what convex. The general direction of this socket is to the distal. The socket which supports the first bicuspid is usually divided from mesial to distal by a thin septum of bone, thus forming an outer or Fig. 284. buccal socket, and an inner or palatal socket. This division seldom exists to the full depth of the cavity, but usually begins about midway of its length. The lower margin of this socket is oblong or egg-shaped, its outer or buccal portion forming a larger curve than its palatal. Fig. 285. The lateral walls are slightly concave or flattened, until the point of separation is reached, when they become more circular, the alveoli above this point becoming cone-shaped. "It is not uncommon for this socket to be a single cavity, and when THE EXTRACTION OF TEETH. 423 thus formed it resembles a flattened cone, with the buccal and palatal margins rounded. "The next socket gives support to the second bicuspid tooth, in most instances being a single cavity, but in rare instances it is divided near its upper extremity. In general outline it resembles the socket for the first bicuspid. The socket for the first molar is much larger than any of those previously described; its inferior margin presents a circular outline on its buccal and palatal portions, the former curve being larger than the latter. The mesial and distal walls are flattened and slightly concave. The upper three-fourths of this socket is divided into three separate compart- ments, being so arranged that two are on the buccal and one upon the palatal side. The septa separating the two buccal cavities from the palatal cavity are heavy and strong, while that placed between the two buccal sockets is thin and frail. The two buccal cavities are usually flattened upon their mesial and distal sides. The palatal socket is larger and somewhat deeper than the buccal, the average depth of all being about ^ an ^^^^- Fig. 286. "The socket for the second molar is similar in most respects to that for the first molar, except that it is somewhat smaller. The same description might answer for the third molar socket, which in general is similar to the alveoli for the other molars. It is smaller than the second molar socket, and may be a single cavity, or it may be divided into three or more compartments." (Fig. 284.) The average length of an upper central incisor root in the fraction of an inch is .49; of an upper lateral incisor is .5 1 ; of £> n upper cuspid .68 ; of an upper first bicuspid .48; of an upper second bicuspid .55; of an upper first molar .51; of an upper second molar .51; of an upper third molar .44; of a lower central incisor .47; of a lower lateral incisor .50; of a lower cuspid .60; of a lower first bicuspid .54; of a lower second bicuspid .56; of a lower first molar .52; of a lower second molar .50; of a lower third molar .36.* * These measurements are taken from Black's Dental Anatomy. . 424 THE EXTRACTION OF TEETH. The upper central incisor has a single root which is of conical form, its labial side more flattened than its lingual. The mesial and distal surfaces of this root are also somewhat flattened, and taper gradually from the base to the apex. The upper lateral incisor has also a single root, which is conical in form, and much more flattened from the mesial to the distal surfaces than the root of the central incisor. At the junc- tion of the root with the crown this root is circular in form, the labial portion forming the segment of a larger circle than the lingual portion; it is generally a straight root. The upper cuspid has also a single root, which is the largest and longest of any of the teeth; it is rounded on the labial and lingual surfaces, the labial forming the segment of a larger circle than the lingual. This root gradually diminishes in size from the neck of the tooth to its apex, and forms a perfect cone. The upper first bicuspid has usually two roots (although sometimes it has but one), w^hich are quite similar in form. The buccal root, however, is usually a little longer than the lingual root, and both roots taper to slender apexes with an inclination to curve at their extremities. The point of bifurcation of these roots is usually some distance above the neck of the tooth. When this tooth has a single root, it is much flattened from the mesial to the distal surface, indicating a tendency toward the formation of two roots. The second upper bicuspid has usually a single root which is round on the buccal and lingual surfaces, and flattened on the mesial and distal surfaces. The upper first molar has three roots, two buccal and one lingual, the disto-buccal being the smallest, and more rounded than the mesio-buccal root. The lingual root is the largest and longest of the three roots, forming a long curve which ends in a sharp-pointed apex. The upper second molar has also three roots, two buccal and one lingual, which are much smaller than those of the first molar, and are more inclined to converge than to diverge. In general outlines they resemble those of the first molar. The root of the upper third molar, like the crown, is subject to a greater variety of form and number of roots than any other tooth in the mouth. Normally it has the same number of roots as the two preceding molars, but sometimes as many as four or five are developed. Frequently, the three roots are so fitsed together as to present a single root with a line of demarcation between them, thus indicating by such an outline the character of the tooth. The lower central incisor has a single root which is usually smaller than that of any other tooth, and is flattened from the mesial to the distal surface, while its labial and lingual surfaces are rounded. The THE EXTRACTION OF TEETH. 425 broad mesial and distal surfaces of this root, which is straight, taper gradually from the neck to the apex. The root of a lower lateral incisor is shghtly longer and larger, but in other respects is similar to that of the lower central incisor. The root of the lower cuspid is shorter and more flattened on its mesial and distal surfaces than that of the upper cuspid. Its labial and lingual surfaces are convex, and, like that of the upper cuspid, the labial forms the segment of a larger circle than the Ungual. The root of the lower first bicuspid is usually single and straight, tapering gradu- ally from the neck to the apex. Its buccal and lingual surfaces are convex, while the mesial and distal surfaces may sometimes be slightly convex, or flattened, and present a slight longitudinal concavity. The root of the lower second bicuspid is also single, and is larger and longer than the root of the lower first bicuspid, and its mesial and distal sur- faces are also similar. In some cases it tapers gradually from the neck to the apex, while in others its apex may be blunt and rounded. The roots of the lower first molar, two in number, situated imme- diately beneath the mesial and distal halves of the crown, are greatly flattened from the mesial to the distal surfaces, and each is broad at the neck from the buccal to the lingual surface. The mesial root is usually larger and longer than the distal root, the latter having a longi- tudinal depression which renders it weaker than the mesial root. The distal root is generally straight, and gradually tapers from the neck to the apex, ending in a pointed extremity. The lower second molar has also two roots, a mesial and a distal, which are generally closer together than those of the lower first molar, and are less flattened upon their mesial and distal surfaces, and are more rounded, and taper more gradually from their necks to their apexes, which terminate in rounded ends. The roots of the lower third molars are norrrially two in number, like those of the lower first and second molars, but frequently a single conical root is presented; in other cases three roots may be developed, which are usually crooked and irregular, with a tendency to diverge from the crown. Under normal conditions, and if performed on scientific principles, tooth-extraction is not a difficult operation; although cases are some- times met with, where, owing to abnormal conditions, the operation requires considerable judgment and skill, severely trying the patience of the operator and the endurance of the patient. It is therefore difficult to formulate special rules which may be literally followed. The axiom, which is an established rule in all surgical procedures, that "every operation is performed quick enough that is performed 426 THE EXTRACTION OF TEETH. well," is particularly applicable to tooth-extraction. A kind manner and a tender regard for the physical and mental suffering of the patients, on the part of the operator, will, in the majority of cases, so impress them, that they will quietly submit to his judgment and skill. It is well never to promise more than it is probable can be performed; and in the case of children, to adhere to the truth, for deception may render a first operation easy of accomplishment, but will react in the case of a second one, and leave such unhappy impressions upon the mind that years cannot entirely efface. Excessive solicitude should also be avoided upon the part of the operator, and in all cases patience and gentleness should be exercised. The unnecessary display of instruments, together with the preparation of them in the presence of the patient, should also be avoided. While it is true that the most expressive lamentations by the patient do not invariably indicate acute suffering, yet there are other cases where no outward manifestations of pain may be exhibited, and at the same time the effect on the nervous system be such as to severely tax the vital energy. Hence it is better not to exact too much of a nervous patient, who may heroically nerve herself to quietly endure intense suffering, and show no visible signs of agony. The question as to "whether or no a tooth is to be extracted" may be answered as follows: " When a tooth or a part thereof can be made of no further use to the patient, or when its retention cannot be ac- complished with comfort to its possessor, or when its presence prevents the correction of more important teeth, it should be extracted." Such an answer may embrace all indications for this operation. On the other hand certain conditions which have been termed "contra- indications" against tooth-extraction have been advanced with more or less reason. The following are the more important: The avoidance of such an operation during the periods of menstruation, gestation, and lactation, as it may seriously interfere with these functions. The more prominent of these contra-indications, however, is the condition of pregnancy, as the shock of such an operation as tooth-extraction may, it is asserted, cause miscarriage at certain periods of its existence. The term "abortion" signifies the expulsion of the product of conception from the womb before the end of the yth month, and is the great accident of pregnancy. It is most liable to occur during the 3rd, 4th, and 5th months of gestation, for the reason that at these periods, there is no adhesion between the ovum and uterus. As soon as the chorion and the decidua are developed, separation of these organs becomes more difficult, and THE EXTRACTION OF TEETH. 427 miscarriage is not so prone to occur; hence, the danger of such an ac- cident diminishes as gestation advances. When it is absolutely necessary to extract a tooth at a certain period in this condition, and palliative measures have failed to give relief, and extraction will prove to be a lighter tax upon the patient's vital powers than a severe and prolonged attack of toothache, and especially if a proneness to abortion exists, the family physician should be con- sulted, and the dental practitioner be governed by his opinion. The pathological conditions of the uterus which predispose to abortion, comprise all that interfere with the development of the ovum, such as displacement, inflammatory affections of the lining membrane, uterine tumors, disease of the ovaries, rectum and bladder; the most common causes of abortion are to be found in the ovum. An affection which has been regarded as another contra-indication is hemophilia (hemor- rhagic diathesis). This condition is characterized by severe bleeding from trivial injuries, and is generally hereditary, and transmitted through the females to their male descendants. It is due to a decrease of coagulability in the blood; also to changes in the vessels, such as may be caused by disease, the vessels becoming so weak as to be unable to withstand the normal pressure. Hemophiha may occur during the course of scurvy, purpura, leukemia, etc. When such a diathesis is present, proper measures should be resorted to for controlling the heart's action and increasing the coagulability of the blood, such as the administration of acetate of lead in two grain doses every two hours, ornux vomica, or aconite, or digitalis, or gaUic acid, or chlorid of iron, or the following formula: I^ — Infusi digitalis, 5ii Ext. ergotae, fluidi, Tincturae krameriae, aa 3j Dose: — A tablespoonful as required. Also such styptics for application to the bleeding cavity, as adrenalin chlorid, tannic acid, antipyrin, chlorid of iron, powdered subsulphate of iron, orthoform, etc. Extreme debility and nervous depression have also been regarded as contra-indications against tooth-extraction, the latter often resulting from dread of the operation. The pain of an aching tooth may sometimes aggravate the symptoms of an existing disease, or may at least retard recovery, when sedative treatment is indicated, such as the administration of bromid of potassium, or sodium, valerianate of ammonia, etc., with tonics. The condition of the membranous tissue of the mouth must also be considered, such as erysipelatous inflammation, for example. 428 THE EXTRACTION OF TEETH. owing to its tendency to spread so as to involve the glands and throat, as a result of tooth-extraction. The nervous affection known as epi- lepsy, characterized by convulsions and loss of consciousness, the existence of which is generally made known by the patient prior to the operation, has also been named as one of the contra-indications against tooth-extraction; but from the fact that proper precautions can be taken to guard the patient against any injury occurring to him during the existence of the paroxysm, this affection need not prevent the per formance of the operation. The extraction of the deciduous teeth requires so little force, owing to the degree of physiological absorption of both their roots and alveolar processes at the period when their removal is required, that it may be considered a simple procedure. Care, however, must be taken not to injure the developing permanent teeth located directly under the deciduous ones. The greatest difficulty met with is the task of gaining the consent of such young patients. A false promise not to hurt will destroy the confidence of the patient in the veracity of the operator, and what the latter may gain by deception at one operation will only increase the difficulty at a subsequent one. The most important matter connected with the extraction of the deciduous teeth, is for the operator to possess an accurate knowledge of the order in which nature proposes to replace these teeth with the per- manent ones; for in no instance will any interruption with this order be tolerated, without such results occurring as the irregular arrange- ment of the teeth of the permanent set. The following is the order of eruption of both the deciduous and permanent teeth: DECIDUOUS TEETH. PERMANENT TEETH. Central incisors s to 8 months First molars 5 to 6 yeara Lateral incisors 7 to 10 " Central incisors 6 to 8 First molars 12 to 16 " Lateral incisors 7 to g Cuspids 14 to 20 " First bicuspids 9 to 10 Second molars 20 to 36 " Second bicuspids 10 to 12 Cuspids II to 13 Second molars 12 to 14 Third molars 17 to 21 The -first step in the operation of tooth-extraction is to make a care- ful examination to determine the location and condition of the tooth to be removed, its relations to the adjoining teeth, and the general state of the mouth; and, if an anesthetic agent is to be employed, the systemic condition of the patient. The second step is to select the proper instruments to be used during the operation. The third step is to determine the direction in which the THE EXTRACTION OF TEETH. 429 force it is necessary to employ can be applied in the line of least re- sistance, owing to the difference in anatomical structure, the number of roots, the class of tooth, and the position of the tooth in the alveolar arch. The operation itself may also be divided into three stages: i. The application of the forceps in order to secure a firm hold on the tooth to be removed, which is usually the upper part of the cervical portion or neck (Fig. 283), so that the edges of the beaks of the instrument may be forced between this part of root and the margins of the alveolus; for by thus opening the orifice by expansion, or by a slight fracture of these edges, the removal of a normally formed tooth is greatly facilitated. 2. The application of the required degree of force by which the pericemental attachment of the tooth with its alveolar cavity is loosened. 3. The careful removal of the loosened tooth from its cavity, and from between the jaws and over the lips, in a manner that w^ill prevent injury to the adjacent teeth, and laceration of the lips by the ragged decayed tooth crown; or by the loosened tooth suddenly leaving its cavity, as in the case of a lower tooth, and the forceps fracturing another in the opposite jaw. Hence, the lips of the patient, as well as the fingers of the left hand of the operator holding the lips open, should be protected by a napkin. Each stage of the operation should be com- pleted before beginning the succeeding one, and no movement be made by the forceps more rapidly than the eye can follow. In performing this operation, the object should be the removal of the entire tooth, with as little mutilation of surrounding soft tissues as is possible. The application of three forces is usually regarded as necessary in ex- tracting, namely traction, rotation, and pressure; "traction" is de- fined as the drav/ing force, "rotation" is the turning around on an axis or center; "pressure" is the force exerted by one body on another — applied to this operation, it is the force used on a tooth when raising and pushing it from its cavity. Position 0} Operator and Patient. — ^The position of the operator in performing this operation, and also that of the patient, should depend upon the teeth to be extracted — whether upper or lower teeth; whether the teeth are on the right or the left side of the mouth. For extracting the upper teeth, the operator should occupy a position on the right side of the patient, whose head should rest in the depression of the head-rest of the dental chair, the back of w^hich should be lowered at about an angle of forty-five degrees. In such a position the head of the patient is thrown well back, being encircled by the left arm of the operator which rests on the edge of the head-rest, thus giving the head a firm 430 THE EXTRACTION OF TEETH. support by pressure against his breast. The fingers of his left hand are used to distend the lips of the patient, and also to retain a napkin in place, so that injury of the lips may be prevented while the de- tached tooth is being removed from between them. For extracting the upper teeth on the right side, the position of the operator should be to the right and a little to the front of the patient, who is seated in the dental chair, with an observance of the directions already given. For extracting the upper teeth on the left side, the position of the operator should be on the right and a little more to the front of the patient, than for the teeth on the right side. For extracting the lower teeth, the operator should occupy a posi- tion on the right, but more toward the rear, of the patient, with the palm of his left hand pressed against body of the lower jaw over the cheek, his fingers over the body of the lower jaw, and his thumb de- pressing the lower Up, and assisting in supporting the jaw. The back of the dental chair, which is lowered, should be almost vertical, permitting the patient to assume a more upright position. A small stool for the operator placed to the rear of the chair, wull enable him to overreach the head of the patient, and permit his having more com- mand of his right arm and wrist. For the successful removal of both upper and lower teeth, it is necessary that the head of the patient should be so firmly supported that the entire force exerted by the operator should be borne by the tooth, and this force so controlled as to prevent injury, either to the adjoining teeth, or to those in the opposite jaw, by a loosened tooth suddenly leaving its cavity. Instruments Employed for the Extraction of Teeth. — ^The instru- ments employed for the extraction of teeth are forceps, elevators, and the screw. There are special recognized forms of forceps adapted to the different classes of teeth, and also other forms which are applicable to teeth presenting abnormal shapes of both crowns and roots. Per- haps the best rule to follow is for the operator, after some experience, to employ those forms with which he is the most successful. The early dentists employed very uncouth instruments for extract- ing teeth, and the now almost obsolete turnkey of Garengeo was con- sidered to be a great improvement on the extracting instruments that preceded it. This instrument, the use of which has been productive of many serious accidents, consists of either a straight or bent shaft, and two or more hooks, with a bolster to rest upon the inner surface of the gums over the alveolar cavity of the tooth to be extracted, which forms the fulcrum. After the use of the lancet to separate the gums, THE EXTRACTION OF TEETH. 43 1 the pointed beaks of the hook are firmly attached to the outside sur- face of the neck of the tooth, the handle of the key grasped firmly with the right hand, and the tooth raised from its cavity by a firm and steady rotation of the wrist of the operator. With the improved instruments used at the present time, the direction of the force is in the line of the axis of the tooth, while that of the key is made in a lateral direction only. To perform the operation of tooth-extraction successfully, the operator should be provided with forceps of the best quality, so well tempered that the beaks will spring instead of fracture under the force to which they are subjected, and so shaped as to permit of accurate adjustment without interfering with the adjoining teeth. The beaks should also be so curved as to overreach the crowns of the teeth when their edges are applied to the necks, and thus avoid fractures of the crowns; and so thin and sharp that the use of the gum lancet may be dispensed with in most cases, and permit of the edges of the beaks being introduced between the gum margin and the thin walls of the orifices of the alveolar cavities, A badly adapted forceps presents to the surface to which it is applied but one or two points, which prevent the application of the necessary traction. The handles of these instruments should be wide, and of such a form as will fit the hand of the operator, be perfectly rigid when firmly grasped, and serrated on their outer surfaces to prevent slipping through the hand. A curve on the end of one of the handles is adapted to the little finger of the hand holding the instrument, and materially assists in applying the required force in the case of firmly implanted teeth. The manner of applying and using the forceps may be described as follows: The forceps is firmly grasped in the right hand with the palm of the hand inward and the thumb on the top, with its ball pressed between the handles in the bifurcation, with such force as will regulate and limit the pressure of the beaks after their edges are applied to the portion of the tooth at the neck to be grasped. By using the ball of the thumb in the manner described an increase of the pressure, to a greater degree than is necessary, on the tooth may be avoided without incurring the danger of crushing it. The first or second finger (according to their length) of the hand holding the forceps should be inserted between the handles near the bifurcation, and employed for separating the beaks, and also to assist in maintaining a firm hold on the instrument. The little finger of the right hand is applied to the curved end at the extremity of the outer handle of the forceps, and, with the serrated outer surface 432 THE EXTRACTION OF TEETH. THE EXTRACTION OF TEETH. 433 of the handles, will prevent the instrument from slipping through the hand. The inner beak of the forceps, when applying it to the neck of the tooth, should be placed in position first, then the outer beak, care being taken to keep these beaks clear of the crown of the tooth, and thus avoid its fracture; then, according to the class of tooth, rotation, or the outward and inward motions are made to break the attachment of the tooth to its alveolar cavity. In some cases, especially of frail roots, it may be necessary to apply forceps with cut- ting-edged circular beaks to the outside of the outer and inner walls of the alveolar cavity and cut through such walls, in order to obtain a firmer hold on the stronger portions of such roots. What is termed " a cultivated sense of touch" is soon acquired by the operator, when the loosening of a tooth by rotation, or the outward or inward motion" (according to the class of tooth) becomes at once apparent; or its yielding in one direction only, when a change in the application of the traction may secure its removal from its cavity with slight effort. Cases have occurred in the practice of the writer where a firmly im- planted cuspid tooth has resisted all efforts to remove it, to such a degree as to render it dangerous to apply greater force, when the postponement of the operation to the following day has resulted in its easy extraction, owing to the effects of the inflammation excited in its investing mem- brane by the previous attempt. After applying the beaks of the forceps to the neck of the tooth, they should not be pressed together more tightly than is necessary for securing and maintaining a firm hold; otherwise there is danger of fracturing the tooth. Considering the different classes of teeth, the following rules may be formulated for their removal with the forceps: Beginning with the upper central and lateral incisors, which may be grouped together on account of the similarity of their roots and environment, the force for loosening these teeth should first be applied in the direction of a line drawn through the greatest axis of the tooth at the same time using rotation, as these are single rooted teeth of conical form; should any portion of the alveolar walls of their cavities be in danger of removal by the strong adhesion of their roots, the rotary motion w^ill loosen it. In all cases the pressure applied should be labial, for the reason that it is in the line of least resistance, the alveolar process on the labial aspect being thinner than on the lingual; another reason is that pres- sure toward the lingual causes more pain. Labial pressure, when not excessive, will enlarge the orifice of the alveolar cavity, without the danger of fracturing the margins to any degree. (Fig, 287.) 28 434 THE EXTRACTION OF TEETH. THE EXTRACTION OF TEETH. 435 436 THE EXTRACTION OF TEETH. For the extraction of the upper cuspids a considerable degree of traction is usually necessary, more, perhaps, than for any other teeth, as these teeth have the longest roots, and are, as a rule, firmly implanted in their cavities. The traction applied should be in the labial direction, as this is in the line of least resistance, and as soon as an impression is made, and the tooth slightly loosened by such force, then slight rota- tion will assist in displacing it; the rotary motion will also tend to detach any portion of the process which may adhere to the root, as this is by no means an uncommon occurrence. The rotary movement should be applied in such a manner that the labial portion of the tooth is moved toward the median line, from the fact that the root of this tooth frequently has a direction backward. (Fig. 288.) For the ex- traction of the upper bicuspids, traction is generally employed. In the case of the upper first bicuspid, the force employed should be limited in degree, as this tooth has usually two slender roots and the process over the buccal root is thicker than over the root of the cuspid, hence, there is danger of fracturing this root if great force is employed. On this account the force should be carefully applied, and in the lingual direction to a greater degree than in the buccal direction. The second upper bicuspid has usually a single root which is round on the buccal and lingual surfaces, and flattened on the mesial and distal surfaces, the root being disproportionately long compared with the circumference of the neck. For the extraction of this tooth, traction may be applied in the line of least resistance, which is the buccal — that is according to its outward inclination, and when shghtly loosened, the rotary motion may be resorted to completely displace the tooth. (Fig. 289.) For the removal of the upper first and second molars, which may also be grouped together on account of similarity in form, position and environment, traction should be applied first in a buccal direction according to the outward inclination of the tooth, for the reason that the resistance is first offered by a single or lingual root, and when an impression is made upon this root, that of the two buccal roots, the smaller ones, is soon overcome, and a slightly rotary motion, although the roots may diverge to a degree, will displace the tooth; the process is also thinner on the buccal aspect than on the lingual. Care should be taken, however, not to make the buccal pressure too great, for in such a case considerable fracture of the buccal wall of the process may result. (Figs. 290, 291, 292 and 293.) For the extraction of the upper third molars, traction should be made downward and back- ward. The roots of this tooth are frequently so fused together as to present but one of an irregular form, which permits the use of the rotary THE EXTRACTION OF TEETH. 437 438 THE EXTRACTION OV TEETH. 1-1 THE EXTRACTION OF TEETH. 439 motion in the direction of the raphe at the median line of the hard palate or roof of the mouth. These teeth being the last in the upper arch, and near the tuberosity of the process, are not usually very firmly implanted, especially as the alveolar process surrounding the distal surfaces of their necks is but imperfectly developed. Hence care should be taken that a tooth of this class, when loosened by the forceps, does not escape from the instrument, and slipping down the throat enter the larynx (Fig. 294) . It is not unusual for the upper third molars to erupt on the outer side of the alveolar ridge with their occlusal sur- faces directed toward the cheek; in such cases the direction of the force should be outward and upward, and the mutilation of the tuberosity be avoided on the account of the danger of penetrating the antrum, and also of injuring the vessels and nerves passing through the tuberos- ity in this locality. As the gum tissue at the distal surface of these teeth often adheres strongly to the neck, it is better to employ the gum lancet to sever the connection, and thus avoid the danger of tearing the gum. The form of lancet represented by Fig. 310 (3) answers for such cases. The lower teeth are usually more difficult to extract than the upper ones, especially the lower third molars when partly erupted or impacted, owing to the space between the second lower molar and the ascending ramus of the jaw not being sufficient for their accommodation; such a difficulty may be greatly increased when the patient is unable to open the mouth to any extent owing to the inflammation incited by the tooth itself in the adjacent tissues, or by other pathological conditions, such as alveolar abscess for example. The fact that the inferior maxillary bone is a movable one, also adds to the difficulty of extracting the lower teeth, as it is necessary for the operator to hold the jaw immovably, by placing the palm of his left hand over that portion of the cheek covering the body and border of the bone, his fingers under the jaws, and his thumb pressing down the lower lip, and also assisting in sup- porting the jaw. The external oblique line extending across the outside surface of the lower jaw, from near the mental process to the base of the ramus and the mylo-hyoid ridge on the innersurfaceof this bone, which extends from a point near the base of the bone at the median line, and passes backward and upward to the base of the ascending portion, giving origin to the mylo-hyoid muscle which forms the greater part of the floor of the mouth; both of these prominences add to the thickness of the alveolar ridge over the roots of the lower molars, and increase the difficulty of extracting them; this is especially the case with the 440 THE EXTRACTION OF TEETH. THE EXTRACTION OF TEETH. 441 442 THE EXTRACTION OF TEETH. lower third molars, when their roots curve posteriorly, or these teeth are but partly erupted, or impacted. For extracting the lower central and lateral incisors and cuspids, these teeth having single, straight and mesio-distal flattened roots, the operator in removing them occupies a position a little back on the right side of the patient, who is seated more uprightly in the dental chair than for the removal of the upper teeth. A narrow beaked forceps is employed for the removal of the lower central and lateral incisors, such as are represented by Figs. 295 and 296, and the outw-ard and in- ward motions are applied with a force sufficient to expand, but not to fracture to any degree, the orifices of their alveolar cavities. The lower cuspids, being larger teeth, and more firmly implanted than the lower incisors, require stronger forceps for their removal; hence, the lower bicuspid forceps, represented by Fig. 297, is generally employed. For extracting the lower first and second bicuspids, which have generally but a single root, which is straight, tapering gradually from the neck to the apex, that of the second being larger and longer than that of the first bicuspid, the motion required should be out- wark and inward, accompanied with a slight rotary motion as the tooth is yielding, to assist in detaching the process from the root. (Fig. 298.) For extracting the lower first and second molars, the outward and inward motions should be made; the roots of these teeth, two in num- ber, usually diverge and stand across the alveolar ridge, being situated immediately beneath the mesial and distal halves of the crowns. They are flattened on their mesial and distal surfaces, and broad at the neck from the buccal to the lingual surfaces; the mesial root usu- ally being somewhat larger and longer than the distal root. The instru- ments adapted for their removal are illustrated by Figs. 299 and 300. The points on the concave edges of beaks of this forceps should be inserted in the space between the roots on each side of the alveolar ridge, the concave surfaces grasping the convex surfaces of the roots. Care should be taken when applying the forceps that no part of the tongue be inclosed between the beaks and the roots; the danger of a lower molar suddenly leaving its cavity after being loosened, and the forceps fracturing teeth in the opposite jaw should be guarded against. Some prefer to apply the first force, in loosening these teeth, in the direction of the inclination of the tooth in its cavity, either outward or inward. When the two roots of a lower molar diverge greatly it may become necessary to use the splitting forceps represented by Fig. 301, the sharp edges of which are carried down over the crown to the space between the roots, and the crown divided at the center of the buccal THE EXTRACTION OF TEETH. 443 444 THE EXTRACTION OF TEETH. and lingual surfaces, using a strong pair of root forceps to remove each root thus separated. The extraction of a lower second molar is usually an easier operation than that of a first molar, for the reason that the roots of the second do not diverge from the neck to the same degree. The extraction of the lovi^er third molar, when the teeth occupying the arch are not unusually large, or irregular in position, is not difficult and can be accomplished by the forceps represented by Fig. 302. The outward and inward motions are usually employed for loosening the lower third molars, except in cases where, owing to 11 i- Fig. 303. — Deciduous Teeth lorceps. rriegularity in position, it may be better to apply the first force accord- ing to the outward or mw ard inclination of the tooth. The operator and patient occupy the same positions in the extrac- tion of both the lower first and second molars. When the force it would be necessary to use in attempting to extract an abnormally shaped, or located lower third molar would endanger the bone of the jaw, and especially when there is a backward curvature of the root, it is better to cut away the process with a bone-cutting bur, operated by the dental engine, until a sufficient portion of the root is exposed to be grasped by the forceps; this method can also be followed in the case of hypercementosed roots of other teeth; also in cases of partly THE EXTRACTION OF TEETH. 445 m ."2>. 5., A V E N U E , A CHARQE WILL BE MADE FOR ALLAPPOINTMENTS BROKEN WITHOUT TWENTY-FOUR HOURS' NOTICE. .^. _ A^cr^ cc?h ^f/i/i.ext'n/rrve^ric. Ine cc/.. cc^^A ^^^. IF UNABLE TO KEEP THIS APPOINTMENT PLEASE GIVE DUE NOTICE, OTHERWISE CHARGE WILL BE MADE FOR THE SAME. CONSULTATION HOURS FROM 4 TO 5 P.M. Fig. 365. — (Appointment Cards.) sideration; many men seem to feel that their own time is the only thing to be considered. Just as much importance should be attached to the time of the patient. As is indicated by the appointment card (Fig. 365), a patient is given an appointment for a definite day and hour; that hour belongs to that patient and should be as nearly as 528 THE MANAGEMENT OF AN OFFICE PRACTICE. possible fulfilled to the minute. Habit can accomplish much in pre- paring for the proper arrangement of a day's work so that the various appointments may not conflict or overlap too greatly. Nothing but a serious complication is a sufficient excuse for the consuming of one patient's hour for the benefit of another. It is just that a broken appointment, i. e., one broken without due notice, should be charged for, and it is equally just that a patient should receive full value in time for an appointment set and without delay. There are occasions when a patient's time may be of vastly greater commercial value than the operator's and if the rule of charging for "broken appointments" were reversed and the dentist were the one to be charged for unfulfilled obligations, the full force of the justice of this statement would be acknowledged. EXAMINATION RECORDS. Too great value cannot be placed upon accurate records of all operations performed. Three forms of examination cards are here given, any one of which is ample for the requirement, and a choice of which is a matter of individual taste. (Fig. 366, Nos. i, 2 and 3.) When a patient first presents himself, in addition to the reference card already mentioned (Fig. 364), the results of the oral examination should be recorded and filed in proper case or cabinet in alphabetical order. This card may be kept separate from record cards of opera- tions performed, or used as both examination and record card till filled, when a second card for the same patient, marked Number 2 on its upper left hand corner, may be substituted and the old card filed away. Some practitioners dispose of old cards, but it is a wise practice to file all such away so that at any future time a consecutive history of every operation performed may be at hand. Many times these records are invaluable for legal purposes if any question or statement should arise demanding enlightenment or verification. Also, much value has been given them as means of identification of those who have lost their lives by accident. DAILY RECORDS. As each operation is performed it should be marked upon the dia- gram and either by sign or number its character recorded upon that part of the chart assigned for such record. This should be done immediately to avoid error. Some practitioners make no further daily record than this; others prefer to add a record upon a separate daily record card (Fig. 367) showing all operations done during the day, which, when transferred to the proper accounts, may be filed away DAILY RECORDS. Examination Blank No. i. 529 (Front) 1 1 i i z C3 05 UJ '. . • ' m Fig. 366. — (One of Three Examination Blank Forms.) 34 53° THE MANAGEMENT OF AN OFFICE PRACTICE. Examination Blank No. 2. r\ A n ,-■. 7^ .-^^ ® %flr Suggested bv S. H. Guilford, A. M., D. D. S., Examination Blank No. 3. Date ■ 190 ¥mmmm Examination of M teeth. Remarks: Fig. 366. — (Nos. 2 and 3 of Examination Blank Forms.) DAILY RECORDS. 531 190^ Month,. Day,. NAME. REMARKS. CHARGES. ' Fig. 367. 532 THE MANAGEMENT OF AN OFFICE PRACTICE. among a collection which may be referred to at any time for informa- tion regarding any particular day's transactions. Still others make a record in a daily record book. As each patient's operation is com- pleted the time consumed is marked, operations indicated, etc. The advantage of the daily record book is that it gives an opportunity to in- sert every important event of the day, as, for instance, the visit of a patient to pay a bill or to leave an important message which should receive prompt attention at the end of the day's duties. A portion of a page of such a record may include items as follows: Monday, December 17, 1906. 8:30. John Jones. Root treated | 2 I Amalgam | 8 D 9:25. William Brown. Bill paid $18.00 9:;^o. Mrs. N. Smith. I Gold I 4j^-0. (Send appoint, to Miss Smith for Jan'y.) Reference to various teeth should be made by numbers as indicated : Permanent Upper 8 I 7 I 6 I 5 j 4 I 3 I 2 I I I I I 2 i 3 i 4 I 5 I 6^L7 \ l_ 8 1 7 I 6 ! 5 I 4 I 3 I H n H n 3 I 4 I 5 I 6 t 7 T 8 Lower Temporary Upper V IV III II I I I II III IV V V IV III Il"rj I II III IV V Lower The various surfaces should be affixed, CARD SYSTEMS. All these record cards demand system and today little in the way of business method is not applicable to systematic arrangement. That systems are time savers is an undoubted fact. Such being the case, there is no excuse for their non-adoption. There are many laudable systems which may be found on sale at the various dental depots. One system, arranged by Dr. Guilford, of Philadelphia (Fig. 368), comprises a full set of cards, with guide cards and places arranged for the tabulation of all necessary data including charges, etc., CARD SYSTEMS. 533 thus doing away with all necessity of other book-keeping. This feature appeals to many while others prefer to have no record of charges upon cards. The cards in these systems are usually divided into three sections each arranged alphabetically; the first division is for cards of patients whose operations are incomplete; second, for those whose operations Reduced Illustration of Guilford's Tin Case Outfit. Actual size, 5 Inches wide, 8'A Inches long, 7H inches high. The accompanying method is an adaptation of the Card Index System to the use of the dentist. It takes the place of the Ledger, Cash-book and Bill-book all of these accounts being kept on separate cards in the same box under suitable headings. Fig. 368. have been completed but whose bills are not paid; the third for com- pleted cases whose accounts are closed. The advantage of having an added record in book form is that it gives a duplicate in case a card should be mislaid or destroyed, and also affords an opportunity to have at a glance all data desired for long periods. The following (Fig. 369) is a page from a loose leaf ledger which is an admirable example of what concise records may be. This page has 45 lines upon it, but the number may be made whatever is 534 THE MANAGEMENT OF AN OFFICE PRACTICE. Remarks. SOUj I ^> (J 1 1 1 1 1 1 -= 1 1 1 HOXVHadO •ON X-aVHD «i •ON uoi^cjado 1 +j >tB-ax £ rr, ^uaunfedJX 3uiiBin33-a ai^ld Xbiui aapug ] UMOJQ 1 d^OaAjaN | j „ iioi:^Baiquio3 | aoo-g 1 ^uaui33 1 „ BqoJ3' results, that is his course to pursue. If he cannot get the desired results in this manner, then let him try the methods used by the writer. About all the special films, of which he has heard prepared for den- tal work have been tested and, he has finally adopted for general use the Regular Cine Positive Film made by the Eastman Kodak Co. ^Vhile this is not as rapid as many other films, it has the advantage of being thin and flexible, develops up quite rapidly, and fixes out ex- ceedingly quickly, all of which are very material advantages in his method of work. Films must be kept in lead-lined boxes when near the tube for their protection from the rays. The student can make up these boxes from one-sixteenth-inch sheet lead for small sizes, and line a suitable cigar box (wide and flat) with the same for a larger one. For taking skiagraphs of the head or face, with the plate or films APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. 561 outside of the mouth, undoubtedly special X-ray emulsions are more suit- able. A film or plate may be held in place by adhesive strips or ban- dages during long exposures, but m rapid work the patient or an assist- ant can hold it. Film Holders. — While the patient invariably holds the films for all upper skiagraphs, the writer is never satisfied to have tlie patient hold it for lower teeth. There is too much uncertaint}' about having it held immovably, and too many pictures were spoiled by not getting in the required region. So he now always makes a film holder for each sepa- rate case. The three minutes spent in the work is a good investment of time, as with such a holder, the desired region is always in the field. This technique is as follows: The patient is placed in the dental chair, and a piece of Xo. 28 aluminum plate is cut to suit the case. If it is a molar or bicuspid, it can be longer than for a cuspid or incisor. A row of sUts one-fourth inch deep are cut along one edge with a pair of scissors. These are then bent over in an uneven row, nearly to a right angle. If it is a molar to be skiagraphed, the aluminum is left flat. For the other teeth it is bent to conform to the shape of the arch. A small piece of modeling compound is softened by diy heat and attached to the row of lugs of aluminum (p^e^'iously warmed) and then placed in the mouth, and while the aluminum is held firmly against the arch, the modeling compound is worked over the crowns of the teeth, and at the last moment the patient closes gently upon it. Care must be taken that when the patient does close down, that the aluminum is not forced away from contact with the arch. If that has happened, it can be readily pushed back to place. This fixture is then removed and chilled by a blast of cold air or under the tap and then dried. With a little experience these holders are quickly and easily made. The prepared film encased in rubber is now attached to this alu- minum plate by two clamps, made of strips about three-fourths by one-eighth inch of aluminum plate (same gauge) bent upon them- selves and closed on to the film holder and film by pliers. Or the original piece of aluminum may be cut a little longer than otherwise necessar}', and slotted at each end, and the ends bent over on to the film packet (Fig. 387). It is possible for a patient to present with inflammation about a lower third molar erupted or unerupted, and who is unable to open the mouth to any appreciable extent, and therefore it is impossible to follow the usual course to obtain a skiagraph of this molar. For such cases the following method was devised. A piece of aluminum plate X'o. 28 gauge was cut as shown at A, Fig. 388. 36 562 APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. Along the line BC the plate was bent upon itself, and again it was doubled upon itself at DE, the end B being clamped in place by a strip of same material at GF. Along the line IH, it was again doubled, making a U-like holder for holding the film. The corners Fig. 387. were then rounded, a film placed in position when the completed and loaded appliance was, as shown at J. K shows a strip of aluminum from which the clamps are cut. Fig. 388. The film can thus be placed in the mouth fiatwise, though the teeth can only be opened one-quarter of an inch, and when once inside by careful manipulation it can be gradually worked into place back of the recalcitrant third molar, and held there while it is skiagraphed APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. 563 In Fig. 389 is shown a model of a case, and the skiagraph of its unerupted third molar taken by the aid of such a film holder, while the front teeth were separated only one-quarter of an inch. Naturally this film holdei is also adapted to the holding of films when the mouth can be opened normally, but the writer prefers, as a rule, the modeling compound-aluminun combination which requires no holding by the hand, and insures the film being always exactly where needed. Fig. 3S9. Care of the Films. — Upon receiving a new lot of films from the fac- tory, the outside envelope is dated; it is taken into the dark room and opened, care being taken to keep out of the direct rays of the ruby lamps, and in as near total darkness as it is possible to work. Two sheets are removed and placed in a lead box provided for them which is immediately covered, and the balance are replaced in their envelopes, put in a small iron box (an ordinary bank box to be purchased at any stationer's is most suitable) and a heavy rubber band put around it to keep it closed, and immediately taken into another room, and put in some safe place. Preparation Board. — This is a piece of board about ten by twenty- four inches, one-half of one side of which is covered with ordinary white oil cloth, and the other half covered with black oil cloth, which furnish readily cleanable surfaces upon which to prepare our films. 564 APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. All white objects are to be placed upon the black end, and dark ob- jects such as black rubber, etc., are placed upon the white, and any- thing can thus be plainly seen under the faint ruby light. Enclosing Films. — ^The lead box with its films, a pair of scissors, and a pair of flat pliers are placed upon our preparation board. From the box of Akron black dental rubber No. 14, we remove several sheets and cut them crosswise into three equal parts. The linen is then removed from just as many pieces of rubber as we have films to enclose, and the rest are put back into the box. Those needed for immediate use are laid in a row upon our white oil cloth against which they will show up in sharp contrast in the feeble ruby light. A pattern, one and one-quarter inches by one and one-half inches of black paper is laid beside the rubber. Now the white light is shut off and the red lamps turned on. The lead box containing the films should be out of the direct rays of the ruby lamps — the less light upon it the better — ^and should always be kept closed. Taking from it the two, four by five-inch sheets, and examining them by the ruby light, one sees that while one side is very glossy, the other side is somewhat "dead." The latter is the emulsion side, and should be touched as little as possible, for finger marks on them might show. These sheets are placed together, emul- sion surfaces in contact, when by the aid of the black paper pattern, three strips, each one and one-quarter inches wide by five inches long, are cut from them. Again laying the black paper pattern upon these strips, from each are cut three films each one and one-half inches long. Thus eighteen films of the standard size are cut from the two sheets. The object of having the pattern black is that it can be readily seen against the white film. The film being four by five inches, if the pattern is laid upon it in the right way, it will be cut into nine one and one-quarter by one and one-half inch films, with but little waste. If the pattern is put on virrong, it will only cut six films and the balance will be wasted. These cut films are put in a small pasteboard box without a cover, which in turn is placed in the lead box and covered. Film Cutter. — In place of the black paper pattern, a regular film cutter as supplied by any photographic supply house shown in Fig. 392 may be used. With this, films may be cut to any sizes desired, and it is a very convenient device. Taking two of these cut films, and putting their emulsion or film surfaces together, they are carefully laid on one end of a piece of black rubber, so that the latter overlaps them a very little on the three sides APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. 565 (Fig. 390A). The free end of the rubber is carefully doubled over the films, and the edges of the rubber pinched together all around by the pUers (Fig. 390B). Film Packet. — The packet is then held close to the lamp, the ragged edges of the rubber trimmed ofif (Fig. 390C) (the outline of the film being visible through the rubber) and very carefully examined to see if the edges are safe, for if at any spot the rubber is not well sealed, the film will be "light struck" and ruined. One of the pieces of linen with which the rubber sheets were separated, is then doubled over it and it is put in one of the little lead boxes until the instant for use. Fig. 390. The white light is now turned on, ruby lamps extinguished, every- thing put back in place, and the preparation board also put away, for this is only used when preparing films. Testing out the Plant.— 'Let us now assume that our outfit has been race ved, and we are ready to set it up and test it out. A place for each and every appliance is selected, and each is always to be put back in place that it may be readily found when wanted. The coil is placed in position, the no D. C. electric light wires having been previously led 566 APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. to a convenient outlet, and provided with fuses vi^ith a carrying capacity of at least ten amperes more than the maximum our coil will take. The electrolytic interrupter is next filled to the marked line with acidulated water of the proper density (a Baumd hydrometer being used) and the platinum point turned up so that it barely protrudes from its sheath. This interrupter may be placed in another room if found necessary, though it is most desirable to have it at hand. The electric wires are then connected to their proper terminals according to the instructions accompanying the coil. The handle of the rheostat is then placed about midway between the terminals, the disk and point of the coil are placed about six inches apart, and the switch closed. If the spark is seen to jump from the edge of the disk to the point, the connections are right, but if from the point to the center of the disk, they are wrong, and the wires must be reversed where they are attached to the coil. The terminals on the coil are next separated the full distance, the rheostat handle placed so that it cuts out all of the resistance, and the switch closed. If the current jumping across the terminals is a good fat fuzzy flame, looking somewhat like a caterpillar, fast work is assured. If it is a thin blue streak, the reverse must be expected. This weak spark, however, may be caused by faulty adjustment of the platinum point in the interrupter, which should therefore be turned down so as to allow the passage of more current. If upon throwing on the full current, a spark jumps across the terminals, and then all is dead, it probably means a fuse is blown. Heavier fuses, or lessening the exposure of the platinum point in the interrupter will overcome this diflSculty. The operator must keep on hand some extra fuses for instant use in case of emergency. The maximum spark of which the coil is safely capable is gotten by carefully adjusting the platinum point. Current should never be left on the coil any longer than necessary, or it may be injured. With the coil working satisfactorily, the next step is to test the tube. This is carefully clamped on the tube carrier, swung into position as nearly at right angles to the coil as possible, the wires attached to its terminals, the rheostat handle set about in the center, and the switch closed. If it lights up as shown in Fig, 380, it is properly connected; if as in Fig. 384, it is not, and the reversing switch upon the coil should be quickly thrown over. The current should never be put through a tube unnecessarily. It uses up the tube, changes its vacuum, and a puncture might result. If for any reason, it is advisable to run it, the current used should be re- APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. 567 duced by rheostat. The maximum current should only be put through it when absolutely necessary, as for instance when testing it with the penetrameter, or doing actual work. With the coil and tube in good working order, the next step is to test the tube according to instructions given with the penetrameter, and with the efficiency of our tube assured, we are now ready to take a skiagraph. For our first experimental picture, it is well to take an assistant, and try the upper incisors as the posing for these will now be described. Posing the Patient. — ^The correct angle at which to place the tube for skiagraphs of the upper teeth cannot well be taught by the corre- spondence method, there being so many factors to be considered. Upon the position of a tooth in the arch, and the height and shape of the vault which varies in each individual must be based the position of the tube, and only experience can teach the process. The writer believes that Dr. Weston A. Price was the first to publish diagrammatic instructions in this regard, and with his kind permission they are now given as they can hardly be improved upon. He says, "Much skill is required to place the film and tube in the proper relations to the teeth to produce a correct shadow of the parts without distortion. We all know how seldom our own shadows repre- sent our true height or shape, because the source of the light and the surface receiving the shadow are not in the proper relation to the object casting the shadow. Each of these three factors must be in correct relation to the other two, but one of them, the teeth and surrounding structure casting the shadow are by their peculiar position practically fixed and the others must therefore be adjusted to them. The shape of the arch prevents one placing the film in the best position to receive the shadow, viz. : in parallel planes. This produces a distortion which must be overcome by placing the source of the light in just the position that will shorten the shadow just the extent that will correct the elonga- tion of it produced by the film not being in a parallel plane to the roots of the teeth. We do not have this trouble with the lower bicuspids and molars, but we do with the lower cuspids and incisors, and with all the upper teeth. "The correct image can be secured in two ways, by holding the film away from the crowns of the teeth the same distance that it is away from the roots, or by raising the source of the rays. The former is more difficult, and the results are not more satisfactory. The three diagrams shown in Fig. 391 will illustrate this distortion, and how to correct it. 568 APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. " Fig. I shows diagramatically the relation of the tooth and the film to each other, and the result of taking a skiagraph with the tube oppo- FlG. 391. site and at right angles to the plane of the teeth, and shows the distor- tion by elongating the shadow of the root. The skiagraph A opposite APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. 569 was made with the tube in this position, and you will notice the very long roots, nearly twice the correct length. Fig. 2 shows the distortion by placing the tube so that the rays fall at right angles to the plane of the film, thus greatly shortening the shadow of the roots. The skia- graph B opposite shows the same teeth as A, but taken with this position of the tube. The next Fig. 3 shows the correct position for the tube, in order to produce a shadow of the teeth that will have the minimum of distortion, and the skiagraph C opposite shows the same teeth as A and B taken from this position, and you will note easily the difiference in the results." Guided by the above clear-cut instructions of Dr. Price, the student must study carefully the angle at which he poses his patient, and if the result is not good, he must reason out the "why," and endeavor to correct the fault next time. With the patient in the dental chair, the writer "gets a line" on the path which he thinks the rays should take, and then with a blue pencil makes a dot on the exact spot upon the face upon which he will focus the rays, and this simple expedient assists him wonderfully. And right here is where the very great advantage of the rubber covering of the film is shown. If our film, of standard size as pre- pared, proves too large or not the best shape, it is taken into the dark room and quickly cut to the desired size and shape, and the edges of the rubber pinched together. It is obvious that for skiagraphing a lower cuspid situated as it is in the sharp curve of the arch, that a film only about five- or six-eighths of an inch wide, held snugly against the arch would give a better result than a square film one and one-quarter inches wide in a stiff paper covering. Returning to our proposed experimental picture, the resistance is all cut out at the rheostat, the full twelve-inch spark gap is opened on the coil, a one-half inch series spark gap is left at the tapes, and the third terminal is adjusted to a four-inch gap. Focal Distance. — ^A word about the focal distance for taking skia- graphs. The effects of the X-ray upon the photographic film depends upon the distance between the film and the tube; the greater the dis- tance the longer must the exposure be. Believing that no bad results may be expected from very close exposures of from one to three- sec- onds when all precautions are taken, the writer sees every advantage in short close exposures, and such is his practice. Our patient is now seated in the chair with head placed in the proper position. We examine the roof of the mouth, and remembering Dr. Price's instructions, get a mental line as to what angle the rays 570 APPLICATIOM OF THE ROENTGEN RAY TO DENTISTRY. should strike the lihn, draw the tube over, and adjust it in position with the position finder in range with the apex of the roots of the cen- trals, as nearly as we can judge. The position finder is then removed, the film placed in position, and the patient directed to hold it there, pressing it firmly against the roof of the mouth with the thumb of either hand, the fingers being closed in on the palm in order to be out of range, and the lower teeth closed up gently against the thumb, in order to steady the lower jaw. Taking the Skiagraph. — A glance verifies the position of rheostat lever terminals and connections— //ffs final glance is always taken — and then the switch is closed coincident with which motion, the following sentence is begun. "George Washington one," and with the "one" completed, the switch is quickly opened. This means that an exposure Fig. 392. — From left to right: Lead box for four by five films. Clips. Develop- ing tubes and jars. Pad, pencil, scissors and pliers. Examination box. Box of small envelopes. Two small lead boxes for cut films. Red and black rubber. Devel- oping box and cover, iron box for stock films, black paper and film cutter. of practically one second has been made. While a stop watch may be used for accuracy the counting oflf of seconds in this manner, George Washington one, George Washington two, George Washington three and so on, will be sufficiently accurate if the operator will practise a little with a watch so as to get the proper speed. The exposure having been completed, the tube is swung out of the way, the film packet removed from the patient's mouth, and the next step is its development. The Developing System. — ^The writer's system of developing his skiagraphs was devised to meet his immediate requirements, which are that such work is usually done incidentally, while other work is being carried on, and no one person exclusive time is devoted to it, and the danger of accidentally spoiling a skiagraph must be reduced to the minimum, if not altogether eliminated. By having the different solutions in use, each always in some dis- APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. 57 1 tinguishing jar, anyone of several persons can go into the dark room, take up the work in hand, and continue it without any instructions from his or her predecessor. These jars occupy less space than dishes or other vessels, and require the minimum quantity of solution. The Developing Box. — ^The developing of films in these jars takes place in a galvanized iron box with a deep cover. In this manner much of the developing and fixing processes proceed in the dark. The cover rendering the box light proof, the work can be left in safety while the operator leaves the room, or is otherwise occupied with the light on (Fig. 392). However, one of the greatest advantages lies in the fact that these various httle jars filled with their respective solutions may be left in place, protected from extraneous influences for three or four days, during any hour of which they are ready for instant use. As long as the developing solutions remain clear and colorless, they are fit for use, and the fixer, of course, may be used a dozen times or more. Paraphernalia. — Ks for the paraphernalia used in the dark room its name is legion, and in order to save time one must have all that may be necessary. The following are upon the writer's shelves: Five by seven-inch developing trays (for plates or large films oc- casionally used.) Four-ounce, twelve-ounce and sixteen-ounce beakers. Glass rods. The necessary bottles for the developers, fixing bath, formalin, alcohol and thyoxidant. Seven sets of one and one-half-ounce jars about two and one- quarter inches deep, each set being distinguished from the other by its color or shape. One galvanized iron developing box about twelve inches by nine inches by four and one-half inches deep, with loose cover one and one-half inches deep. Three lead boxes for films. Black rubber for enclosing films. Red rubber for backing stereo- scopic films. Clips for drying films. Envelopes for temporarily holding films. Pad and pencil for necessary notes to be made at the moment. Pliers for pinching the edges of rubber together. Scissors. Black paper for patterns. Some tap water is unfit for photographic work. The operator should learn from some local photographer whether or not his supply is suitable, and if not distilled water should be used for the solutions. Tap water can be usually used for washing. The writer has naturally tried very many developing agents, and has finally settled down to the exclusive use of the following which 572 APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. in his hands appear to yield the best results month in and month out. Developer A. Water 12 ounces Metol 22 grains Hydrochinon 22 grains Sodium sulphite (dried) 97 grains Developer B. Water 12 ounces Potossium bromide 12 grains Sodium carb. (dried) 97 grains Keep in well-stoppered bottles; if after long standing they become discolored they should be discarded. This is used for starting the developing. When ready to develop take equal parts A, B and water; mix well. Developer C. Water 10 ounces Sodium sulphite (dried) f ounce Sodium carbonate (dried) \ ounce Hydrochinon i dram Potassium bromide 7^ grains Use full strength for completing the development Fixing bath. No. I. Water i quart Hypo-sulphite of soda 8 ounces No, 2. Water 8 ounces Sulphate of soda f ounce Powdered chrome alum \ ounce Sulphuric acid -^^ ounce Immediately add No. 2 to No. i while stirring. This will keep indefinitely before using. This fixing bath can be used repeatedly, hardens the film somewhat and gives a uniformly better result than a plain solution of one ounce hypo to four ounces of water, though the latter can always be fallen back upon in an emergency. Should be filtered when necessary. For hardening the film (to be used in warm weather) immerse the film for five minutes in Formalin 5 parts Water 95 parts For quickly eliminating the hypo, the film should be first rinsed under the tap for two minutes then immersed for five minutes, no longer, in: Lumierre's thyoxidant i part Water 100 parts and then washed again under the tap for three minutes. APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. 573 Returning to the work of developing the skiagraph just taken, the developing box is put in the sink. In this box at its left end is placed one of the white jars into which is put one-half ounce each developer, A, B and water Next to this jar is placed a jar of water for rinsing, then a little blue jar filled with the C developer and lastly a brown jar full of fixer. It is possible in cool weather to develop a film in a single develop- ing solution, fix it in plain hypo, wash it under the tap and hang it up to dry. The results obtained in this simple way are not always the best, and will not suffice at all in warm weather. Moreover this is somewhat a lengthy process and ofttimes a picture must be finished in short order. So then while additional steps must be taken, at times these curtail the time required and eliminate all possibilities of "frilling" the films in warm weather. Temperature of Developer. — The best results are obtained when the developing solution is at a temperature of between sixty and seventy degrees. Should the temperature be above seventy degrees, put an inch of water in the developing box and a few pieces of ice. With one of the little lead boxes at hand, we darken the room and turn on the ruby lamps. The films are removed from the black rubber by tearing off one end of the rubber, and opening it up. One film is placed in one of the little envelopes (previously labeled with the patient's initials) and put in the lead box and covered and the other is placed in the end of a developing tube, emulsion surface toward the center, and immersed in the white jar (left end) given several vertical shakes to remove any air bubbles from the surface of the film, and left there (Fig. 393). Both films are never developed at the same time, for should white light accidentally be let in, only the pj^ ^q, one would be spoiled, and the other could be fallen back upon. As a matter of fact the duplicate film is rarely developed; usually only when some defect or accident mars the first. Sometimes it is developed, and given to the patient though this is seldom. The cover of the developing box should now be put on, in order to keep the ruby light from the film, and we wait for about a minute. Upon opening the box we now see the advantage of having the film in the tube, as by grasping the end of the tube which stands out of the solution, we remove it and the enclosed film for examining near the ruby light without getting any of the solution on our fingers, or en- dangering the film by handling. If the dark outlines between the roots 574 APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. of the tooth are not well developed, the film must be returned to the same jar for another short period. As soon as this stage is reached, that is, the dark streaks are well visible, the film is immersed in the next jar (water) for rinsing, and then put in the adjacent blue jar which contains the contrast developer, and the box covered. We examine this film from time to nme, keeping it near the ruby light as little as necessary until the white spots have about faded out of sight, and the film is almost black all over, when it is again rinsed in the water jar, and placed in the fixing bath (brown jar). The cover of the box can then be put on, and we can go off for ten minutes, at the end of which time the fixing will be complete. This is determined by the film being black on both sides. If it is not thoroughly fixed, it will show white on the back of the film. When the whitish aspect of the film has entirely disappeared, it is said to be "cleared," and a film should be allowed to remain in the fixing bath in order to be thoroughly "fixed out," about twice as long as it takes to clear it. Hardening the Film. — ^The skiagraph may now be removed, rinsed and examined, but it must not be held very near an electric lamp or the heat will spoil it. It is rinsed again in the cool water in the box (rinsing it under the tap might ruin it) and then placed in the formalin for five minutes; no longer. This hardens the film so that it can now be rinsed under the tap, even in warm water for thirty minutes, after which it can be hung up by a clip, preferably in front of an electric fan to dry. An automatic washing and drying machine was devised, in which films could be placed, and required no further attention. These films were washed for a predetermined length of time, and then automat- ically dried, but the scheme was not found very satisfactory in actual use and was therefore abandoned. Right here must be emphasized the fact that unless the hypo is thoroughly eliminated, the film will be found to have become spoiled in the course of a few months, and the student will naturally ask what amount of washing is really necessary for this thorough elimination of the hypo. The length of time absolutely necessary for this washing should be determined by each operator for himself, after which he may feel safe for the permanency of his work, and this is ascertained as follows : Test for Hypo. — ^Make the following stock solution: Permanganate of potash 8 grains Caustic soda 7 grains Water (distilled) 8 ounces APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. 575 Into a small tumbler of pure water pour four drops of the above solution and stir well. This makes a solution of a delicate purple hue, and we know that if a little hypo is added to this, it will turn to a greenish hue in about seven minutes. Taking a finished film out of the fixing bath, it is washed for twenty minutes under the tap, and then allowed to drain into the above solution, and after a few minutes we will probably find that the stated reaction ensues, and therefore we know the film is not j^et cleared of hypo. After washing it ten minutes more under the tap, we test it again as before, when we find no reaction, consequently we may feel assured that thirty minutes of washing is necessary, and that should then be adopted as the minimum time all films will be washed. Naturally when time allows, it will be wise to wash them a little longer, but never less. Hastening the Work. — No matter how pressed for time, just so many minutes will be necessary for properly developing and fixing the Fig. 394. film. However, by rinsing it for two minutes, then immersing it for five minutes in Lumierres' Thyoxidant (a hypo eliminator) and then washing it under the tap for three more minutes, all the hypo should be eliminated — thus twenty minutes have been saved by that process. Again if it is immersed in grain alcohol for three minutes, it may then be dried before an electric fan in three minutes more, thus saving much time in that step. To prevent curling during this process, the film should be held by two clips as shown in Fig. 394. Improving Skiagraphs. — ^When a photographic plate is overexposed or underexposed means may be taken for reducing the one, or intensify- ing the other, but the writer has met with no success in improving un- satisfactory skiagraphs. This, however, should not deter the student 576 APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. from making such attempts, and determining for himself what is possible in this line. Lead Backing. — ^It has been frequently stated that better results will be obtained if the film is backed by a piece of one-sixteenth-inch lead when being exposed, but repeated experiments have shown that with the writer's technique at least, the lead makes no appreciable difference, and he never uses it. Sizes of Films.— Films up to two by two and one-half inches in size may be developed in the writer's tubes and jars, but all over that size must be developed in the usual photographer's trays, or saucers may be used, in which case the film is best handled by a clip caught on to one corner. Making Photographic Prints. — ^For all practical purposes the films are all that are required, more especially as certain essential details may not appear upon the prints. However, prints are necessary at times, therefore the operator should obtain the latest paper on the market, accompanying which will come full directions for its use, and with his knowledge of developing, he should have no trouble in making excellent prints, but if he can get this done by some photographer who makes it his business to do "amateur" work it would probably be advisable. The developing of his films, however, should be done in his office, if not by himself, by one of his assistants under his directions, who should thus be able to obtain more satisfactory results than anyone else. Bromide Paper. — In the earlier days, when the development of a skiagraph required a very long time, frequently an hour or more, a piece of bromide paper would sometimes be put in with the film or plate, which after exposure could be quickly developed and so a finished picture produced in much less time than required for the film or plate. But these bromide pictures were always lacking in detail, and therefore never very satisfactory, and in view of the rapid work now done, this paper is no longer used. Consulting a Photographer. — Any beginner in X-ray work who has had no experience in ordinary photographic work, and is not familiar with its details had better call to his aid some good film developer who can give him many pointers, and by an actual demonstration of the process, save him much time which would be otherwise spent in lonely experimentation. After that he must work out in his own way the troubles he meets. Deterioration of Films. — ^Unexposed films and plates deteriorate with age, and just how long they may be kept and still be good depends .\PPLICAT10N OF THE ROENTGEN RAY TO DENTISTRY. 577 upon the season of the year, climatic and other influences. Usually they keep better in winter than in summer, but the best plan is for the operator to obtain them in small lots and frequently. Testing Films.— To test a film, develop it without having exposed it. If it comes out of the fixing bath clear, it is good, but if it comes out cloudy and dark, it shows the emulsion has deteriorated, and the balance of that lot must be discarded. DENTAL SKIAGRAPH BY Dr. C. Edmund Kells. No Date M Age Examined for Make of Plate. Time Distance Developer Tube Remarks Fig. 395. Filing Skiagraphs. — Some operators who use films of a certain size only for all cases, have cardboard or celluloid "mounts" in which the films are placed and filed away (Dr. Satterlee, Jr., has gotten up a very attractive celluloid mount) but as the writer does not limit his work to 37 578 APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. the possibilities of any one size and shape of film, but cuts them to best suit the case in hand, he cannot use such a method. Skiagraphs are taken on films ranging from two by two and one- half inches (when they are placed horizontally in the mouth between the teeth) down to five-eighths by one and one-eighth inches for lower cuspids, and cut to the shape most suitable to the case in hand. They are properly " tagged," as will be described, and put in prepared envel- opes (Fig. 395) and filed away alphabetically in suitable boxes, and so any skiagraph may be quickly found, no matter how long since it has been taken. Fig. 396. Marking Skiagraphs. — ^In taking skiagraphs upon plates of any size, there is always plenty of room thereon for any required marks of identi- fication, the usual one being to place small lead or brass numbers or stencils upon the outside of the plate holder, which being opaque to the rays, would show upon the plate. However, when it comes to using films within the mouth, this method though early used by most operators, has been practically abandoned as unsatisfactory, and no APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. 579 Other system being used, films have not generally been marked, and there was no means of identifying them. This has been a constant source of worry to the writer, until recently, when it occurred to him to tag his films, and since this system has been put into practice, it has proven to be all that can be desired. Small merchandise tags are used, upon which can be written all that is necessary, and as they need never be removed, a film can ever after be identified (Fig. 396). There are times, however, when some identification mark must be recorded upon the film. Suppose, for instance, a patient presents for which skiagraphs of both lower third molars are desired. Before tak- ing the right one, some small metalhc object, a small lead R for in- stance is placed upon the outside of the packet upon the surface pre- senting toward the tube, care being taken that this does not come right behind a gold crown or extensive filling, and is outside of the area desired in the field. After exposure, if this precaution has been taken, the shadow of the figure will be found upon the film, and it is only necessary to note upon its tag, that this marked film is of the right side, when the two films can be identified with their respective sides. Recording Skiagraphs. — When a patient is taken into the dark room for the purpose of having a skiagraph taken, a lady assistant {absolutely necessary when the patient is a lady or young girl) follows with the skia- graphic record book. This is a little blank book in which she always records at the moment, the patient's name, and the length of the ex- posure, and also makes any additional notes that may be deemed necessary. Testing Developing Agents. — The writer's method of testing the comparative value of different developers is as follows: to compare Metol-Hydrochinon with Rodinol for example, two films are super- imposed and enclosed as usual. They are then placed in the mouth of one of his assistants and exposed. One developing jar is filled with the Metol-Hydrochinon developer, and another with the Rodinol, and placed in the developing box along with the jars of water for rinsing and fixing baths. A memorandum is made that the Rodinol is in the jar nearest the operator. The room is darkened, red lamps turned on, the packet of films opened, and one placed in the developing tube, and then immersed in the Metol- Hydrochinon developer. The second film has one corner clipped off and placed in a tube, and put in the Rodinol, and a note made that the clipped film was developed in the Rodinol. The two films arj sSo APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. then carried through the processes of developing, fixing, washing and drying, and when finished they can be readily distinguished from each other as the one developed in Rodinol is indelibly marked by the clipped corner. Upon a careful examination, it can be seen which developer has produced the better results. Naturally the student should test out a number of developers, and adopt for permanent use the one which suits him best. As many as five films may be developed at once, and marked for recognition by clipping off one, two, three and four corners, by which they may be distinguished from each other, and from the fifth which was not clipped at all. This method of marking films is as efficient as simple, but care must be taken to make the proper notes at the moment, and not rely upon one's memory. Fig. 397. Skiagraphing a Lower Molar. — ^To skiagraph a lower molar or bi- cuspid we place our patient in the dental chair, and'rapidly make a film holder as shown in Fig. 387. We "get a line" on the spot on the cheek (with the mouth nearly closed) opposite the apex of the root of the tooth to be skiagraphed, and mark it with a blue pencil. The film is then attached to the film holder, it is put in place, the teeth closed upon it, and the patient taken into the dark room. She is seated at right angles to the coil as shown in Fig. 397. The tube is swung into position and adjusted so that the centering rod points to the mark on the cheek, while the tube is at right angles to the spot, and in about a horizontal plane. The localizer is removed, the terminals properly connected, a final glance verifies the correct APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. 581 position of everything, the switch is closed for a period of two seconds (tissues are thick here) and then quickly opened. With the film thus clamped in position, and the jaw closed the patient is comfortable, can swallow with ease, and all parts can be held perfectly still. When the patient is holding the film with the finger, swallowing is difiicult, and possibly just at the instant of ex- posure, an attempt to do so is made, under which circumstances the film may be moved and the picture spoiled. Testing the Ruby Lamp. — ^If the light from the ruby lamp is too strong, it will " fog" the films exposed to it, by which term is meant that films developed under it or exposed to it will be affected, and therefore will darken all over, and be ruined under the process of development. As some makes of films are more susceptible to the red rays than others, it becomes necessary for each operator to test out his own lamps, which is done as follows: Take a piece of film, say of the usual size, one and one-quarter inches by one and one-half inches, and cover one-half of it with a sheet of black paper, and lay it upon the top of the develop- ing box directly under the ruby lamp, allowing it to remain there for three minutes. At the end of this time develop and fix it. If it comes out perfectly clear all over, it shows that the exposed surface was not acted upon by the ruby light, and that the lamp is therefore safe. If it comes out with one-half clear and the other half darkened, it shows that the half not protected by the black paper was acted upon, and therefore that the lamp is not safe. This may be remedied by placing a piece of ruby glass under the lamp. The operator's own ingenuity should be exercised in fitting up his ruby lamps, placing them to the best advantage, and possibly arrang- ing them with extra slides of ruby glass, by which more or less light can be used, always remembering that the less light on the films the better, and that their rays should be kept from the films as much as possible. The advantage of the covered developing box is here made manifest. Examining Skiagraphs. — Skiagraphs (films) should be examined by transmitted light, and to be seen to the best advantage, all light rays must be cut off, save those that pass through the film. The writer's scheme for ^^* ^^ examining films of various sizes and five by seven-inch plates is as follows: At the back of one of the shelves over the sink in the dark room, and at just the proper height three Edison plug cutouts, Fig. 398, were screwed to the shelf and frosted 8 C. P. electric lamps put in them and 582 APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. SO connected to two switches just to the right, and under the shelf that either the two outside lamps could be lighted at once, or the center one only, which gives a satisfactory range of illumination, for with these connections either one, two or three lamps can be lighted. Examining Box. — Next a neat wooden box ten and three-fourths by seven and three-eighths by seven and one-half inches was secured, and from it two adjacent sides were removed. In the third side, three holes one-half inch, one inch and one and five-eighths inches re- spectively were bored, and over these, cardboard shutters were pivoted by means of glass-headed pins. In the fourth side an opening four and one-half by six and one-half inches was made (Fig. 392). Now with one open side down, and the other toward the back, this box is placed against the wall and over the lamps with the three small openings in front. In this position it can be illuminated by turning on the switches, and the shutter is swung up from the size opening best adapted to the size of the film to be examined, and all undesirable light cut off, a piece of sheet metal having been laid over the large opening on the top. The film to be examined may be very conveniently held by placing it in a holder made of a piece of ordinary transparent sheet celluloid about three by four inches, and bent upon itself. The film is placed in this holder at one end, and the clip holds the celluloid together (Fig. 396). If one always cuts his films of a standard size, the celluloid film holder devised by Dr. Satterlee should be very satisfactory, but as the writer cuts his film to suit the case in hand, he does not use it. When we wish to examine a five by seven-inch plate this box is reversed, bringing the large opening to the front. Of all the schemes for examining films which the writer has ever seen, this is by far the most satisfactory, and being homemade its cost consists entirely of the little time spent in constructing it. Interpretation of Skiagraphs. — Taking a skiagraph is usually a very simple proposition, but properly interpreting it is ofttimes a much more difficult matter, comes only with practice, and cannot be taught by the "absent method." Skiagraphs are purely shadow pictures, and consequently their taking must be governed by the usual laws which cover the casting of ordinary silhouettes. The lower teeth give the best results, as here the film may be held parallel with the long axes of the teeth and the tube so placed that its rays will strike both film and teeth at right angles. In skiagraphing the upper teeth, it is never possible to place the film parallel with the teeth and therefore the shadows are liable to APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. 583 distortion, which however, may be lessened considerably by the care- ful placing of the tube (see page 570). The relative positions of the various details shown in a plain skia- graph cannot be determined therefrom, therefore it is usually necessary for the operator to know what to expect in order to correctly interpret the picture. Thus when a wire is placed in a root canal one cannot tell from the resultant skiagraph (see Fig. 414), whether the wire was anterior or posterior to the root, or in the canal; as in either position the shadows cast upon the film would be about the same. However, knowing that the wire was placed in the root canal, this skiagraph can be read intelHgently. The enamel is least penetrable by the X-ray and therefore appears white on the filrn. While the roots of the teeth are more penetrable than the enamel, they are sufficiently dense to cast distinct shadows upon the film when close to it. It is often impossible to show the buc- cal roots of upper molars, because the film is too far away, and cannot be placed upon the proper plane, but the lingual root may be clearly shown. The alveolar process between the teeth and above (or below) the roots is quite penetrable, and thus these parts show dark upon the film. Metallic fillings and metal crowns show white, while porcelain being very penetrable leaves no imprint upon the film. Fortunately, gutta-percha and cements are opaque to the ray, and thus root fill- ings of these materials may be readily shown. Pus sacs, fistulous tracts, and loss of tissues generally make the region involved more penetrable than the surrounding healthy tissues, and so may be generally, though not always, recorded upon the film. The pulp chambers and root canals are well shown in all the lower teeth and upper single-rooted teeth. If something appears on the film which is unrecognizable, it may be due to an artefact, and the second film should then be developed. If it should be duplicated here, and still not be understood, a second pair of films should be exposed when, if the same details are shown, it will be recognized that whatever it is, it is a part of the picture and every effort should be made to interpret it. If it does not appear on the second set of films, it proves that it was some defect in the first pair. Caution must be used and no hasty conclusions must be reached when skiagraphs are not perfectly clear. Peridental Membrane. — ^The peridental membrane is quite trans- parent to the ray, and is shown in nearly all pictures, except in cases of planted teeth where it usually does not exist. Usually is italicized be- 584 APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. cause in Fig. 330 under "Planting of Teeth" is shown a replanted lower molar in which the membrane is shown, the only case of its kind ever published, the writer believes. The Secondary Ray. — ^The secondary ray is supposed to originate from any object upon which the direct ray from the tube has been thrown, and is supposed to be harmful. The writer has made many varied and exhaustive tests, but has never yet been able to have the faintest shadow of an object cast upon a film by this secondary ray. While it is impossible to discredit what others claim in this line, he can but believe that for some unexplainable reason, this ray is not created in his own laboratory, and every operator should test this out for his own satisfaction. Characteristics of the X-ray. — ^The value of the X-ray depends upon its remarkable ability of penetrating many substances that are imper- vious to ordinary light rays, but there is no relation in this matter be- tween the two classes of rays. Glass free from lead and lead glass are equally transparent to the rays of light. The former is also very penetrable to the X-ray, while the latter in any thickness is quite impervious to it. Aluminum in thin sheets is quite transparent, while lead is very opaque, hence the use of the former for filters, and the latter for protection screens. The bones are less transparent than the flesh, and hence can be seen in the fluoroscope or shown in the skiagraph. The roots of teeth are also fortunately much less penetrable than the alveolar proc- ess in which they are imbedded, and therefore can be shown in a skiagraph, but the attenuated end of a root may sometimes be lost to view in a particularly dense jaw. So would a small pulp stone be in- visible if situated in the center of dense enamel or even dentin. The uses of dental skiagraphs are apparently limited in a great degree, only by the enthusiasm and imagination of the operator. Some can distinguish plainly in their own pictures (where others fail to see) the three roots of an upper molar, and their root canal fillings. Pulp stones stand out in bold relief to their eyes. They can tell whether or not a filling is dangerously near the pulp and so on. To others the results obtained are far more limited. The writer belongs to the latter class and while he has not been able to accomplish what some others claim, the results obtained are invaluable, and if the student does no better he should not be discouraged. Thus far skiagraphs have been found invaluable to the ^ATite^ in the following cases. APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. 585 To Ascertain to which Dentition a Tooth belongs. — It is seldom that the character of a tooth cannot be safely judged from its appearance by a man of experience, but in a practice of thirty-five years, the writer has met with a very few upon which there could be a doubt. To Fig. 399. Fig. 400. — The dark streak diagonally across the root is an artefact. This was one of our earliest skiagraphs taken on a glass plate. extract a permanent tooth under the impression that it belonged to the first dentition would be a fatal mistake. A skiagraph could usually be relied upon in such a case for a positive diagnosis. In Fig. 399 is shown a permanent second bicuspid in the mouth of a Miss which was diagnosed as a temporary tooth by several very prominent dentists. The skiagraph (Fig. 400) proved it to be a single-rooted tooth, there- fore a permanent bicuspid. Diagnosing Unerupted Teeth. — In no cases are skiagraphs more Fig. 401. — Here the skiagraph shows Fig. 402. — While here it is seen that the that the temporary molar should be- ex- second bicuspid is missing and conse- tracted. quently the temporary molar should be preserved. satisfactory than in diagnosing the presence in the jaw, or the absence therefrom of unerupted teeth, which knowledge is usually necessary for the successful treatment of the case. It is generally considered that the upper cuspids are never absent 586 APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. from but always somewhere in the jaw. Here, however, is a case which appears to be the exception to the rule, the only authentic one met with in the writer's practice. Fig. 403. — Permanent upper second bicuspid missing. Fig. 404. — Permanent cuspid erupted in position of the lateral. Temporary cuspid in place. Permanent lateral missing (a not uncommon condition). Fig. 405. — Permanent lateral missing. Fig. 406. — No lower third molar present. Age seventeen. (Not uncommon.) Fig. 407. APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. 587 Fig. 408. Root Work of all Kinds. — In root canal work of all kinds the uses of skiagraphs are invaluable. The writer early in his X-ray work devised the method of placing fine wires in the roots of teeth previous to skiagraphing them, in order to "get a line" on the length of the roots, size of apical foramina, etc. He frequently skiagraphs a root Fig. 409. — Obtaining the length of lower FiG. 410. — Note the absorption of pos- molar roots. (Note the loop formed on terior root, the fine platinum point upon pressing it down.) Fig. 4n. — "Getting a fine" on a second Fig. 412. — Diagnosing a perforated root, bicuspid root canal. Example of a frilled film. 588 APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. after filling, and if found not well filled it is changed accordingly. ,An entire chapter should be wTitten on this one subject and it is withue- gret that space limits the work to a few illustrations only; Fig. 413. — Size of apical foramen of Fig. 414.— Obtaining the size of fora- upper central. Pulp killed at age of seven men in lateral of adult, by faU. Fig. 415. — Same in child of about eight. Fig. 416. — .\bscess on lower central, child of twelve. No cavity in tooth. Cause unknown. Fig. 417. — Abscess caused by imperfect Fig. 418. — Abscess on upper lateral, root filling. Wire in canal. To Study the cmidilions about the roots of planted teeth and possibly to skiagraph the alveolus before the operation. A condition of affairs may present which appears unrecognizable. APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. 589 At the point marked upon the model there was an unrecognizable condition; a firm particle of exposed bone could be felt with an in- FiG. 419. — Posterior canal of molar ap- parently well filled. Anterior canal im- perfectly filled and large pus sac at its apex. Fig. 420. — Same case few days later. Anterior root refilled. Fig. 421. — Skiagraphing an implanted lateral brought to light an unknown im- pacted cuspid. " The point only of the cuspid is shown in this illustration, but upon the original film much of the crown was visible." Fig. 422. — Central incisor knocked out by fall (uninjured). Replanted. Fig. 423. — Incurable abscess on lower cuspid. Tooth replanted. Fig. 424. — Same case several years later. Pus sac obliterated. strument. It evidently was not a root nor was it the alveolar process. A skiagraph showed it to be a bone "whorl." Skiagraph was kindly interpreted by Dr. Raper. 590 APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. To A'scertain if a Root is Fractured. — ^I'his, however, is only to be discovered by the merest chance, for unless the line of fracture happens Fig. 425. — A hopelessly broken-down lower molar with abscess on one root was extracted and unintentionally put in a porcelain tray and placed in cabinet. Few days later an old patient called with the left upper first bicuspid split in two. It was ex- tracted. The lower molar just referred to was carefully split and the good root put in con- dition, and crowned and implanted -n place of split bicuspid. Skiagraph was taken several years after the operation. Fig. 426. Fig. 427. Fig. 428. — Upper lateral fractured by fall. Fig. 429. — Lower centfal fractured with- in the alveolus without known cause. to lie in the direct path of the rays, it will not be shown, therefore when such fracture is suspected, if the first skiagraph does not show it, others at different angles must be taken. APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. 591 The shape and position of impacted teeth. Impacted third molar shown in Fig. 315. Fig. 430. — An impacted cuspid vvitfi an FiG. 431. — Impacted cuspid having odontome between the roots of the lateral caused the absorption of the root of the and bicuspid. permanent lateral. (Regulating arch bar shown.) Fig. 432. — An unerupted cuspid in the FiG. 433. — The root of a temporary roof of the mouth of an edentulous jaw. cuspid of an adult was crowned. Later Patient over sixty years of age. on trouble ensued and a skiagraph re- vealed the permanent cuspid as .-^hown. Fig. 434. — Supernumerary literal. Model of this case shown in Fi^'. 448. Fig 435 lourth inohir. To learn whether or not there is a fragment of a root in the alveolus the rays are invaluable, but as a rule such skiagrajjhs are loo faint for satisfactory illustrations. 592 APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. In all cases of facial neuralgia where the causes are not discernible, skiagraphs should be taken in the hopes of some hidden cause being revealed. To diagnose supernumerary teeth. Fig. 436, Fig. 437. Permanent central and lateral with one root. To ascertain whether impacted third molars have injured the second molars. (See Figs. 323 and 324.) Fused Teeth. — Sometimes two crowns, usually of the incisors, are fused and it might be well to learn whether or not they have single or double roots. Again, sometimes the roots are fused, and the crowns appear detached when again a skiagraph may possibly lead to some definite knowl- edge. Diseased Antrum. — ^The writer believes that any antrum that can be shown to be .in abnormal condition by a skiagraph, can be as well diagnosed by transillumination. That being the case, why go through all the various time consuming steps for pro- ducing a skiagraph, when the same result can be instantly obtained by means of a suitable electric lamp. Any foreign object within the antrum can probably be better shown on a film placed within the mouth, than on a plate held externally. " To Diagnose for Extraction. — The skiagraph, Fig. 439, assuring the correct position of the unerupted second molar, the hopelessly broken down and abscessed first molar was extracted. Fig. 438. — Temporary lateral and cuspid fused. Permanent lateral missing. APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. 593 In Fig. 440 is shown the case six years later, when we find the second molar has erupted in a perfectly vertical position in contact with the second bicuspid. Diagnosing Caries. — While some operators claim that cavities that cannot be discovered by an explorer will be revealed in the skiagraph, such is not believed to be the case. Any cavity too small (naturally upon a proximal surface) to be disclosed by an explorer will not show upon the film. Fig. 439. Fig. 440. Fig. 439. — At the age of ten a badly broken-down first molar was extracted, a skiagraph having shown the second molar to be in the jaw. Fig. 440. — Model shows case at the age of sixteen. Undoubtedly many other uses than those described may be met with in which skiagraphs would be useful, such for instance as fracture of the jaw, the thoroughness with which bismuth paste has been injected, etc. The writer could only well describe practical cases of his own, and therefore has limited himself accordingly. The proper interpretation of a skiagraph may be at times a very difficult matter, and one must remember that being merely a shadow picture too much must not be expected of it. Therapeutical Value of X-ray. — ^At this date, it is the writer's opinion that there is no place in dentistry for the application of the X-ray for its therapeutical value. STEREOGRAPHS. Thus far we have treated only of plain skiagraphs, simple shadow pictures, and we have seen that the proper interpretation of such depends entirely upon the clinical knowledge of the case as when writing of Fig. 414, it was noted that it was impossible to state pos- tively the relative positions of the wire and root. 594 APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. If, however, the same laws which apply to the ordinary well-known form of stereoscopic photographs are applied to X-ray work, and skiagraphs are taken accordingly, only varying the technique to con- form to the requirements of this work, the results are what we usually call stereoscopic skiagraphs, but what the writer has termed "stereo- graphs" of most marvelous beauty and great accuracy. Most of the doubtful features of the shadow picture are elimi- nated in the stereograph. In the place of a flat picture without per- spective, the stereoscope brings into view a translucent model as though made of glass with the various tooth roots apparently floating in it, while they themselves are also transparent, though naturally less so than the alveolar process. The root canals may be clearly fol- lowed and when filled, any imperfections in the filling are readily perceived. Whether or not a crown post or root filling perforates the side of the root may usually be told. The relative positions of im- pacted or unerupted teeth are also clearly brought into view. Unfortunately the technique for making stereographs is rather difl5cult, or possibly it might be better stated that while the technique is not so very difficult in itself, there are other difficulties in the way, and as a result this work has not yet become general. Assuming that the reader is familiar with the principle of stereo- scopic photography, it is only necessary to say that in making stereo- graphs we proceed in the same manner, that is by taking two skia- graphs from positions two and one-half inches or the average pupillary distance apart, care being taken that the focus in both pictures is upon the same point. The resultant skiagraphs are then properly mounted, and viewed in a stereoscope whereupon the stereograph is the result. The requisites for making stereographs are: 1. A tube carrier which will allow of the quick shifting of the tube, preferably along the arc of a circle the necessary distance of two and one-half inches and 2. A means of readily replacing the first film by a second, and hav- ing them both in practically the same plane. For doing this class of work upon the body generally, there are most beautiful and accurate appliances, but none at this date appear to the writer sufficiently flexible for using films within the mouth, and so appliances were originated to meet his own requirements. By replacing upon his tube carrier clamp E (Fig. 385) by the one shown in Fig. 441 the tube is pivoted at F and swung in a circle, and APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. 595 thus this tube carrier becomes adapted to stereoscopic work. The focal distance of the tube is not a fixed one for stereoscopic work. The stereograph shown in Fig. 442 was taken as follows : Upon the black portion of the preparation board two pieces of ordinary red dental rubber each two and one-half by two inches were placed, and alongside of them upon the white portion of the board two pieces of black rubber of the same size and also a black paper pattern two and one-fourth by one and three- fourths inches. The white light being extinguished, the red rubber is readily seen against the black background, and the black rubber and black paper pattern against the white. Now follow this carefully. Two of the four by five-inch films placed together with emulsion sur- faces in contact as usual, the black paper pattern laid on them, and one pair cut to its size, the corner of one only cHpped ofi', and then they were laid upon the black rubber with the clipped film against the rubber, then covered with one of the prepared pieces of red rubber, and the edges carefully pinched together. Fig. 441. They were Fig. 442. Two other films were similarly cut and arranged, and again the clipped film was placed against the other piece of black rubber, then covered with the red, and edges secured together. The unused por- 596 APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. tions of the films were replaced in the lead box, and box immediately covered and put in its place upon the shelf. A ligature wire was twisted around one of the cuspids of the patient, another piece placed between the opposite cuspid and lateral. She was then posed and her head steadied to the rest by means of a bandage around the forehead. Next the tube was placed in position and focused approximately upon the apices of the centrals. It was then shifted one and one-fourth inches to the left, and the patient earnestly cautioned not to move until permission was given. One of the pre- pared films was taken out of the room, while upon the other a small metal L was placed on a corner of the black rubber, when it was placed horizontally in the mouth, black rubber uppermost with the corner upon which was the L protruding from the mouth. The teeth were closed gently upon it, the switch closed, and thus the exposure made. This was the left eye picture marked L. The tube was then shifted back two and one-half inches to the right, the exposed film removed and taken out of the room, tht- second one put in place, black rubber uppermost and exposed, care being taken to give both films the same length of exposure. It will be noted that both sets of films were placed in practically about the same plane, provided the patient did not move during the interval that the films were exchanged. Upon opening these in the dark room, the advantage of the red rubber base and the clipped films becomes apparent, for the two clipped films form one pair, they having been exposed with the film surface away from the tube, while the un- dipped ones form another pair, and pairs register best in the stereoscope. When mounting them in the stereoscope, the advantage of having the left eye skiagraph identified becomes apparent. Of course other means may be taken for marking the top and bottom (clipped and undipped) films, but the method just described suits the writer best. The development of the films proceeds exactly as with the plain skiagraphs, care being taken that both films are developed to the same density. With the finished stereographs in hand, the next problem becomes their examination, and here again the writer was compelled to resort to originality, for there are no practical small stereoscopes made for this purpose. It is possible of course to make prints, and mounting them on card board examine them in the ordinary parlor Fig. 443. APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. 597 stereoscope, but the best prints are vastly inferior to the original films. The apparatus shown in Fig. 443 was therefore devised It consists of an ordinary parlor stereoscope to the rod of which is secured a rack engaging with a pinion operated by the little wheel Fig. 444 plainly shown. This makes it adjustable to anyone's eyes as by turn- ing the wheel the lenses are moved up or down. The top of the box is of ground glass, grooves being provided by which two or three other sheets of ground glass may be added at will, that the light from the frosted electric lamp within the box may be toned to suit stereographs of various densities. Holes should be cut in a piece of card- board so that when laid on the glass, all extraneous light may be cut off from the eyes and thus the films show to better advantage. For examination the films are placed between strips of clear glass for the better handling (Fig. 444) and placed upon the box (the left eye skiagraph being recognized by the L) and care- ^^' ^'^^' fully moved about until they register, while at the same time the lenses are adjusted to the proper focus by the little hand wheel. Now the advantage of having placed ligatures about the cuspids is seen, for by their aid the films may be readily registered, while without them this is not always so easily accomplished. 598 APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. If these films are transferred to a single plate three by seven inches a "transparency" results, and when this is placed in another of the writer's stereoscopes, Fig. 445, the stereoscopic effect is most beautiful. For practical every-day office work, the first described stereoscope is the quicker and more satisfactory. For exhibition purposes, the latter with the transparency is better, as there is only one plate to handle, and it may be very quickly focused by a novice. The bellows allow of the focusing of the lenses while none but transmitted light strikes the eyes. Stereographs cannot be read at a glance. Some little time is required to properly focus a picture, and then considerable study is necessary to bring out all the beautiful details that lie within its mysterious depths. Fig. 446. Upon placing the left eye picture upon the left end of the examining box, and the right eye picture on the right, the object stereographed is viewed from the point from which the pictures were taken. But if the stereo- graphs are interchanged, then strange to say, it is seen as from the inside of the mouth. The writer much prefers to study these cases from the latter point of view. The value of stereoscopic work is beautifully exhibited in the fol- lowing case. Fig. 446 represents the condition found in the mouth of a girl of ten. Below it Fig. 447 are two plain skiagraphs of the unerupted central taken from two different angles, and so very different are the shadows cast, that it is hard to believe that they are of one and the same tooth; and furthermore, save that the tooth was in the jaw, no idea as to its position could be gained. Upon taking a stereograph, however, the true position of the tooth could be seen. A most interesting case, and one in which the stereograph was invaluable, is shown in Fig. 448. The case is of a lovely little girl of eight. Apparently three teeth are erupting in the space usually occu- APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. 599 pied by the one lateral. They could be the normal lateral and two supernumerary teeth, or one of these might be the permanent cuspid. No one could tell, and something must be done. To extract a wrong tooth or teeth for such a patient would be little less than a calamity. In Fig. 434 is shown a plain skiagraph of the case. From it absolutely Fig. 447. nothing can be learned, but from stereographs (two sets from different angles) is learned positively that the two bicuspids and cuspid are form- ing within the jaw, and that there are only two teeth erupting and not three as the Httle point just protruding through the gum is an excres- cence upon the lingual surface of the labial tooth. This, one observes, Fig. 448. is most valuable information, as from it a satisfactory solution of the problem is possible, that is the removal of the supernumerary (labial) tooth. These stereographs are not shown, because while perfectly satis- factory in themselves, such pictures lose so much in being reproduced 6oO APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. by the halftone process, that they are practically of little value as illustrations. These two cases out of many the writer has had are sufficient to demonstrate, that though stereoscopic work may be somewhat difficult and tedious, the truly wonderful results that may be accomplished through it, render it worth while to master its technique. Dental X-ray Operators. — ^The writer has always contended that the dentist himself should do skiagraphic work and not refer his cases to a general X-ray operator and for the following reasons: 1. They very frequently must be taken at the instant needed, for example, with the dam on. 2. The dentist who knows exactly what he wants brought out in the skiagraph, is much more apt to succeed in getting it in the picture, than the general operator who knows practically nothing of the case. 3. With the skiagraph developed immediately, if it does not prove satisfactory, a second one can be taken with the loss of but little time. To become a good X-ray operator only requires practice, attention to details, and perseverance. Just as a good light, a modern chair^ an electric engine, or compressed air will each and every one improve the quality of the "output" of a dentist, so right to-day, no matter how high his qualifications and great his ability, the class of work of any one will be improved by the installation and successful use of a first-class Roentgen Ray apparatus in his office. Owing to the limited space available many topics and illustrations have been greatly curtailed, but the writer trusts that sufl&cient has been given to start the student upon a work of wonderful interest and satisfaction, the results to be obtained by him being only limited by his unceasing devotion to its study. Thanks are due the Scheidel- Western X-ray Coil Co., Macalaster Wiggin Co., Consolidated Dental Mfg. Co., S. S. White Dental Mfg. Co. and Dr. Price for some of the cuts used. GLOSSARY. A. C. Alternating Current. Alopoecia. Loss of hair. Am- Meter. Device for registering the Amperes flowing through the. line. Anode. The positive terminal within the tube. Artefacts. Products of errors or reagents. APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. 6oi Cathode. The negative terminal within the tube. Cathode Stream. Rays being emitted from the cathode. Cleared. (Photographic term.) Condition of film when hypo has blackened it thoroughly. Cycles. Frequency of alternations per second in an alternating cur- rent. Crooke's Tube. The original tube used in X-ray work in which the vacuum is one millionth of an atmosphere. D. C. Direct Current. Electron. The smallest known component of matter. Electrolyte. (In solution.) A substance capable of being decom- posed by an electric current. Electromotive Force. (E.M.F.) The force that causes electricity to move along a conductor. Erythema. Redness of the skin. Fluoroscope. a device for observing shadows cast by Roentgen Rays. Frilling. (Photographic term.) Emulsion surface becoming wrinkled and indecipherable. Fogged. (Photographic term.) Denoting that the film has been unduly affected either by Hght, X-rays or chemicals. Hypo. Hyposulphite of Soda. Light Struck. (As applied in photography.) When white light has accidentally spoiled a plate or film. Mil-Ameter. Device for registering the milliamperes flowing through the line. Ohm's Law. The strength of an electric current varies directly as the E.M.F. and inversely as the resistance. Penetrameter. Gage for determining the degree of penetration of X-rays. Potential. In electrical parlance equals the term level in hydrostatics. Rectifier. A device for converting an A. C. into a D. C. current. R. Abbreviation of Resistance in electrical terms. Shunt. A conductor connecting two points already in a circuit through which a part of the current is diverted. Stereographs. (Coined by the writer.) A pair of stereoscopic skia- graphs. ELECTRICAL UNITS OF MEASUREMENTS. (International Standards.) The Ampere (French). — The practical unit of electric current strength and equals the current produced by pressure of one Volt 602 APPLICATION OF THE ROENTGEN RAY TO DENTISTRY. through one Ohm. Equivalent to the unvarying quantity of current, which when passed through a standard solution of Silver-Nitrate in water, deposits silver at the rate of o.ooi 1 18 grams per second. The Ohm (German). — ^The unit of resistance equals the resistance of Mercury at the temperature of melting ice, 14.4521 grams in mass, and of a constant cross-sectional area, and 106.3 centimeters long (Ohm's law for direct currents only). The Volt (Volta-Italian). — The unit of electro-motive force (pres- sure) equals the current which driven through one Ohm will produce one Ampere. The Coulomb (French). — ^The unit of quantity equals the amount of current transferred by a current of one Ampere in one second. The Watt (Scottish). — ^The unit of electric power equals the amount of work done by a direct current of one Ampere, at a pressure of one Volt — 1/746 H. P. The kilowatt hour is the commercial unit used for the electric current supplied consumers, equals one thousand watts supplied for one hour. The Joule (French). — ^Unit of electric energy equals the energy expended in one second by the passage of one Ampere through one Ohm. The Farad (Faraday). — ^The unit of electric capacity equals that capacity which with one Coulomb gives a differential of one Volt. CHAPTER XXXIIl. ORTHODONTIA.* BY HERBERT A. PULLEN, D. M. D. PART I. Orthodontia is that branch of dental medicine which treats of the etiology, diagnosis, and correction of abnormal development of the dental arches, dental malocclusion, and consequent facial inharmony. Scope of Orthodontia. — Orthodontia embraces much more than the correction of malpositions of the teeth, which, in its earUer history, was the Hmit of its field of operations, and to-day has developed into a highly specialized science, based upon rational theory and practice. As a branch of the healing art, orthodontia deals primarily with the normal development of the teeth and the dental arches, but secondarily, through contiguity of structure and interrelationship of function, it is directly associated with the normal development of the internal and external face, and indirectly with the functions of respiration, digestion, and nutrition ; hence, by this series of related structures and functions, with the health of the whole body. Diagnostic considerations have assumed such importance as to foster and demand a conception of the scope of orthodontia, which includes as well an intelligent insight into causative factors of abnormal conditions of growth of the dental and maxillary arches, of the adjacent structures of the internal face, the naso-respiratory tract, and also those factors which afifect bodily growth and function as a whole. A more definite etiology, therefore, based upon general as well as local pathology, has been established in orthodontia, for it is clearly recognized that the arrest of growth and disturbance of function of the internal and external face associated with many cases of malocclusion are but symptomatic expressions of disturbances of balance in nutrition or some other vital function of a general rather than a local nature. Again, many of the harmonious and beautiful lines of the face being * The author gratefully acknowledges the courtesies of the Dental Cosmos, the Items of Interest, the Dental Summary, and the Journal of the Allied Societies and the va- rious writers mentioned in the text in loaning cuts for some of the illustrations. Many of the photographs of models of the author's cases were made by Phil. J. Knapp. 603 604 ORTHODONTIA. dependent upon the normal development of the related structures and functions of the mouth and nose, the production of lines of beauty in the face through the development of the dental arches and the correction of malocclusion, by restoring normal balance to the profile, opens up a field of fascinating interest and wonderful possibility. The study of art in its relation to harmony and beauty of the face thus becomes a necessary adjunct to orthodontia. Finally, the mechanical appliances by which these restorations of structure and function of the dental arches, and the corrections of inharmonious facial lines are made possible, call for a comprehensive knowledge of the underlying principles of physics and mechanics, so that these operations may be conducted along strictly scientific lines, whereby the proper standards of efl&ciency in treatment may be maintained. Thus it will be seen that the field of orthodontia is a broad one, requiring a knowledge of the physiological development of the dental arches and associated structures, the relation of associated functions, the local or remote etiological characteristics of malocclusion, its proper classification, diagnosis, and scientific treatment based upon such physiological and mechanical principles as will tend to restore normal relations of the dental arches and lines of beauty to the face, and such improvement in the general health as is possible in the restoration of function of the masticatory and respiratory mechanisms. Trend of Modern Theory and Practice. — Modern orthodontia owes much of its impulse and present scientific trend to Angle,* who, in his presentation of the theory of normal occlusion in its relation to development of the dental arches, and his classification and treatment of dental malocclusion from this basis, gave the first real insight into the broad field of study and investigation of underlying principles in medicine and mechanics which is building up this science as one of the most progressive of modern times. Since the recognition of normal occlusion as the basis of orthodontia, the later trend of orthodontic investigation has dealt with the earlier developmental conditions which precede the attainment of function of the full complement of teeth in normal occlusion, and a more compre- hensive knowledge of the factors which may interfere with these devel- opmental conditions has led to the necessity for, and inauguration of, earlier treatment of incipient malocclusion. It is evident that normal occlusion of the permanent teeth, being the culmination of functional and structural development, may supervene * Angle, Malocclusion of the Teeth, 6th Ed., igoo. DEVELOPMENT OF THE DENTAL ARCHES. 605 only when the normal growth of the dental arches and their associated structures occurs, for if development of the dental arches and related structures is arrested at any stage of growth or is deficient through any cause, abnormal occlusal relations are inevitable. Malpositions of the teeth in general, then, may be considered as the objective symptoms of abnormal growth of the dental arches, usually manifested by an arrest or deficiency in development. Thus it is that the problems of malocclusion are referred back to abnormal developmental conditions, the causes of which are often obscure, because of their being involved in the development of the body as a whole, in factors of metabolism, nutrition, and functional insufficiency of various natures. This recognition of the dependence of normal occlusal relations upon the physiological factors involving as well as preceding the first dentition necessitates a knowledge of the sequence of certain of these developmental processes leading up to the eruption of the permanent teeth and the attainment of normal occlusion. The Arches of the Temporary Teeth. — In order to have a logical and chronological succession of recorded observation of facts, it is necessary to study the dental arches at the latest period before the eruption of any of the permanent teeth, at a time when the deciduous teeth are all in situ, and certain physiological processes are about to take place subsequent to the shedding of these teeth and their replace- ment by the permanent set, these changes, according to the degree of perfection of their physiological performance, having much to do with the normal or abnormal development of the second dentition. Many cases of malocclusion date their inception back to the time when these processes are taking place, and a proper cognizance of them would suggest that assistance be given to these natural processes, if necessary to intervene, rather than to hinder or subvert them through ignorance of their normal function, and consequent ill-advised treat- ment of certain conditions which may present. Fig. 449 shows perfect development of the deciduous dental arch in normal occlusion, at the age of four years, at which time all of the deciduous teeth are in position and accomplishing the function of mastication to the degree necessary for the nutrition of a child of this tender age. The retention of these teeth until the initiative in eruption of the permanent successors has taken place, is a feature of great importance in its bearing upon the normal development of the arches of the per- manent teeth, since the premature loss of the deciduous teeth invariably 6o6 ORTHODONTIA. causes a retardation of development of the maxillary arch which is always productive of a more or less serious malocclusion of the perma- nent teeth. For example, the premature loss of any one of the decidu- ous teeth is causative of a lack of development in the region of the lost tooth, in extent according to its mesio-distal diameter and relative importance in the arch. Directions of Growth of Dental Arches. — As the deciduous dental arches increase in size it will be noted that the growth takes place in three dimensions, length, breadth, and height. Fig. 450 illustrates the growth in height at six years of age over the growth of the same dental arches at four years of age, Fig. 449. The increase in length and breadth of these same dental arches is best observed from the comparison of the upper dental arches placed Fig. 449. Fig. 450. side by side, the line in front of the first permanent molars in Fig. 452, indicating the extent of development of the deciduous arch shown in Fig. 451 before the eruption of the first permanent molars. In two years of development the alveolar processes have grown downward in the upper arch, and upward in the lower arch, and the first molar teeth have come into occlusion, holding the dental arches the proper distance apart, affording new and broad masticating surfaces for use during the shedding of the deciduous teeth, and by their deep cusp interdigitation, accentuating the perfect mesio-distal regis- tration of the dental arches, which the deciduous teeth initiated Developmental Spaces. — While the deciduous arch still retains its full complement of teeth, between the fifth and sixth year, the coordinate and coincident growth of maxilla and mandible are taking DEVELOPMENT OF THE DENTAL ARCHES. 607 place not only in the forward, downward and lateral development, but in an interstitial growth in the alveolar process and maxillae, due to the erupting teeth, which is evidenced by a separation of the deciduous incisors as lateral development progresses. Fig. 453 illustrates the arches of deciduous teeth in occlusion just Fig. 451. Fig. 452. previous to the eruption of the permanent incisors in a patient six and one-half years old, a case in which the anterior development of the process has taken place normally, as noted by rhe spacing between the deciduous incisors. When the dental arches present this appearance Fig. 453. just prior to the eruptive period of the incisors, there is every assurance that the eruption of the permanent incisors will occur without crowding. Occlusal Relations of Temporary Teeth.— All of the laws of occlusion which pertain to the preservation of the integrity of the permanent arches of teeth are in evidence in a lesser degree in the 6o8 ORTHODONTIA. arches of deciduous teeth, both as to the interdependence of one arch upon the other for the preservation of form through normal cusp inter- digitation, and as to the normal growth dependent upon functional activity. It vi^ill be observed in the study of the normal deciduous dental arches that there is a slight overbite in the incisor region, Fig. 449, and that each upper central incisor overlaps the labial surface of the lower central and one-half of the lateral incisor; each upper lateral incisor overlap- ping the distal half of the labial surface of the lower lateral incisor, and the mesial incline of the lower cuspid. The antero-posterior in- terdigitation of the cusps of the cuspids, and first and second deciduous molars is likewise conformative to a normal occlusion and arrangement. The normal occlusal relation of the arches of the deciduous teeth is a very important factor, through the exercise of normal function, in the normal development of the permanent dental arches, the osseous structures in which they are imbedded, and in the production of normal occlusion of the permanent teeth. The growth of the osseous structures which surround the teeth of both the deciduous and permanent dentures is directly dependent upon their functional efficiency. Quoting from Noyes* "Bone is formed and reformed in response to mechanical stimuli, and the entire surface is arranged in harmony with the mechanical stresses which result from the forces applied to the teeth and the surface of the bone^ "The adult maxillary bones, which are such important factors in the beauty and harmony of the face, are the result of the sum total of all of the forces acting upon them." Thus it is that the dental arches, the maxillary bones, and to a certain extent their associated anatomical structures are built up and supported. The function of occlusion in the deciduous teeth, then, plays an important role in the development of the internal and external face. The associated functions of respiration and even of deglutition, f and of the muscles of the face have equally an important role to play in the harmonious development of the structures involving the dental arches. The further factors in development of the dental arches and their surrounding osseous structures are those that relate to bodily development as a whole, such as nutrition, metabolism, etc. Transition Period of Occlusion. — ^The eruption to occlusion of the first permanent molars, Fig. 450, marks the transition stage from the deciduous to the permanent dentition, initiating a period of dental *Noyes, The Alveolar Process. The American Orthodontist, May, iqo8. fNoyes, The Machine and the Power, Journal of the Allied Societies, June, 1914. DEVELOPMENT OF THE DENTAL ARCHES. 609 arch development of much greater extent than that of the deciduous dentition, and commensurate with the more complete and pronounced function of occlusion of the permanent teeth, and proportionate to the development of the face as a whole. The first permanent molars, erupting distally to the deciduous molars (Fig. 454), have a function to perform in establishing the normal relationship between the dental arches during the interval of shedding of the temporary teeth, as well as providing the broadest and best masticating surfaces in the mouth during this period. Also, as Noyes describes them, "the locking of their cusps determines the balance of physiological forces as distributed upon the mandible," referring to "the fulcrum upon which the activity of the>,'muscles attached to the ramus and the posterior part of the Fig. 454. {Noyes.) mandible, and those attached to the anterior portion of the man- dible, are balanced." Occlusal Relations of Permanent Teeth.— The fulfillment of natural or normal development in the dental and maxillary arches in the completed dentition constitutes a normal and ideal relationship of occlusion of the teeth from which it is possible to note deviations in malocclusion, and a guide for comparison in the restoration of normal conditions, viz., normal occlusion. The characteristics of this normal dental and maxillary develop- ment, including the normal development of adjacent structures, are 39 6lO ORTHODONTIA. necessarily specified and limited, and may be comprehended in the following definition. Normal Occlusion is a condition of perfect relationship existing be- tween the normally formed and arranged teeth of normally developed den- tal arches when in antagonism, the mandible being in its farthest posterior position, and in exact median register with the maxilla, and both in normal relationship with contiguous tissues. Fig 455. (Broomell.) Normal occlusion, in the ideal, is seldom found in any type of in- dividual, although the approximation of it in many cases varies but little from the ideal anatomical occlusion. In all branches of art, such as sculpture, painting, architecture, etc., a model of p)erfect art is chosen as a guide to reproductions which rep- resent the highest conceptions of a certain type, whether it be the Apollo in sculpture, the Madonna in painting, or the Renaissance in DEVELOPMENT OF THE DENTAL ARCHES. 6ll architecture. Normal occlusion is the highest conception of a type, not a relative or approximate condition. It is an ideal state of physical integrity, and can only be perfectly conceived in a perfect anatomical subject, which would necessitate, therefore, the normal, typical, and perfect development and relationship of contiguous tissues of the osse- ous and muscular tissues of the head and face, and the harmonious and proportionate development of the facial lines which are conforma- tive to beauty and harmony of the profile. It has been suggested that the word "occlusion" alone be used to designate this ideal relationship; that the word "normal" is un- necessary, since if occlusion is anything, it is normal; otherwise, maloc- clusion is the proper term, but the acceptance of this term without the limiting characteristic which the word "normal" adds to it would be confusing and unwarrantable in referring to the typically ideal anatom- ical occlusion. The commonly accepted use of "occlusion" is in reference to the relation of the interdigitating cusps of the teeth, whether there is a normal, or a malocclusion present, and it may be definitely described as follows: Occlusion is the most constant static relationship of the antagonizing surjaces of the arches of teeth in inter digitation. A Malocclusion is any variation from a normal occlusion either in size, shape or relation of dental arches, or perversion oj inclined cusp planes. The following relations of occlusion of the permanent teeth are based upon the description of normal occlusion by Angle. Characteristics of Normal Occlusion. — Fig. 455 exhibits a skull in which normal occlusion is present, and in which the following characteristics may be noted: 1. The normal shape and size (according to type) of each arch. 2. The normal position of each tooth in each arch. 3. The normal shape and size of each tooth (varying with type) in each arch. 4. The normal relationship of each arch to the other, and of the occlusal inclined planes of the cusps of the teeth in one arch to those of the other. The bilateral arrangement of the muscles, the shape of the arches of teeth, and their harmonious relation to each other; the form, size, and position of the teeth with their cusps interdigitating for mutual support, the proximal contact, the upward curve of the ramus, and the relations of the occlusal planes, all serve the purpoes of increasing the 6l2 ORTHODONTIA. efficiency of the organs of mastication, by providing the means whereby a co-ordination and equilibrium of forces are secured, which are essential for the preservation and function of the organs themselves, as well as for economy of force, and the production of lines of beauty not possible in any other arrangement. In examining the interdigitation of the teeth upon each lateral half, it will be seen that each tooth has two antagonists in the opposite arch, except the lower central incisor and upper third molar; tnis arrangement not only providing the greatest support for the teeth individually and collectively, but also allowing the inclined planes of the cusps of bicuspids and molars the best opportunity for articulating during the lateral excursions of the mandible. Relations of Inclined Cusp Planes. — Beginning at the median line of the dental arches in normal occlusion, the following cusp rela- tions which are conformative to the normal in the bucco-occlusal relations of the teeth may be noted. The upper central incisor is in occlusal contact with the incisal edges of the lower central in- cisor and one-third to one-half of the lower lateral incisor; the upper lateral incisor is in occlusal contact with the remaining two-thirds or one-half of the incisal edge of the lower lateral incisor, and the mesio-incisal angle of the lower cuspid; the upper cuspid occludes with its mesial incline in contact with the distal incline of the lower cuspid, and its distal incline in contact with the mesial incline of the buccal cusp of the lower first bicuspid; the buccal cusp of the upper first bicuspid occludes with its mesial incline in contact with the distal incline of the buccal cusp of the lower first bicuspid, and its distal incline in con- tact with the mesial incline of the buccal cusp of the lower second bicuspid; the buccal cusp of the upper second bicuspid occludes with its mesial incline in contact with the distal incline of the buccal cusp of the lower second bicuspid, and its distal incline in contact with the mesial incline of the mesio-buccal cusp of the lower first molar; the mesial inclines of the mesio- and disto-buccal cusps of the upper first molar occlude with the distal inclines of the mesio- and disto-buccal cusps of the lower first molar; the distal incline of the disto-buccal cusp comes into occlusal contact with the mesial incline of the mesio-buccal cusp of the lower second molar; similar relations of the inclined cusp planes are in evidence in the second and third molars, except that the upper third molar has no antagonizing plane for the distal incline of its disto-buccal cusp. A similar arrangement of the lingual cusps of the upper teeth in their occlusal relations with the lower renders the interdigitation of cusps for mutual support still more pronounced. DEVELOPMENT OF THE DENTAL ARCHES. 613 The object of this complex interdigitation of cusps is to give the greatest support, not only to the teeth individually, but as a whole, their sizes, forms and positions of cusps and inclined planes being best adapted for this purpose. Preservative Forces of Normal Occlusion.— Having outlined the positions of the individual teeth in normal occlusion, it is quite important that cognizance be taken of the forces which tend to pre- serve this normal arrangement, viz.: 1. The interdigitation of the cusps of the teeth. 2. The reaction and dependence of one arch upon the other. 3. The proximate contact. • 4. The; muscular influence of the lips, cheeks, and tongue, labially, buccally and lingually. As one arch is dependent upon the other for its regularity, it follows that a malocclusion in one arch implies a similar condition in the other, and the maintenance of the malocclusion is just as effectual as the maintenance of a normal occlusion through the normal influence of the above-mentioned forces. If the lower arch is contracted and the teeth crowded, the same conditions will be found in the upper arch as a result of the operation of these forces. Distinction between Occlusion and Articulation. — ^The syn- onymous use of the terms "occlusion" and "articulation" is not in accordance with their specifically different meanings, as generally un- derstood by those who have carefully studied them. Articulation is the relation between the antagonizing surfaces of the teeth of maxilla and mandible during the lateral and protrusive excursions of the latter, dependent upon its universal articulation at the glenoid fossa. There are three distinct stages of articulation, viz., incision, attrition, and occlusion. The first two stages represent the mandible in motion; the last, the mandible at rest, the teeth being closed. Occlusion is the passive phase of articulation, as compared to the active phases of incision and attrition. Occlusion represents the static, and articulation the dynamic, relation between the arches of teeth. Some writers have argued that occlusion should represent all that is meant by articulation in its relation to orthodontia, but such a gen- eralization of the term would be absurd, and any attempts at diagnosis of malocclusion from such a variable base would only result in con- fusion. However, it is impossible to completely separate these terms in their bearing upon the normal relationship of the arches of teeth, so intimately are they connected. A normal occlusion necessitates a 6 14 ORTHODONTIA. normal articulation, and a normal articulation necessitates a normal occlusion. The laws of articulation produced the perfectly formed arches of teeth, the depth of the overbite, the length of cusps, and relations of occlusal inclined planes, so that the definite form and positions of the teeth and relations of the arches known as normal occlusion was a pos- sibility. In occlusion, the lines of force are constant in their direction; in articulation, they are ever changing, varying as the relationship be- tween the arches of teeth causes stress to be made between antagonizing tooth surfaces in constantly changing angles. Relation between Overbite and Length of Tooth Cusps. --By carefully studying the forms and positions of the inclined planes of the cusps of the individual teeth, the length of cusps, decreasing in depth from the first bicuspid to the last molar, the depth of the overbite, and the "compensating curve" of the arches, it will be noticed that there is a distinct relationship existing between the length of the cusps m bicuspids and molars, and the overbite, and the "compensating curve," as pointed out by Bonwill. . For example, in cases in which the overbite of the incisors is long, the length of the cusps of the bicuspids and molars is also long, and in cases of short incisor overbite, the length of the bicuspid and molar cusps is correspondingly short. This is typical of the usual denture although cases have been observed showing that this relation was not constant. Turner* illustrates a case of this kind where there is a disproportion between cusp length and overbite. The Curve of Spee. — ^The so-called "compensating curve," or curve of Spee,f bears such an important relation to the length of cusps and overbite that a brief description of it will aid in its understanding. The curve of Spee is the segment of a circle, the path of the arc of which touches the edges of the lower incisors, the point of the lower cuspid and the tips of the buccal cusps of the lower bicuspids and molars, and passes either anteriorly or posteriorly to the articular face of the condyloid process (Fig. 456). In the relation existing between the length of molar and bicuspid cusps, the overbite, and the " compensating curve," or " Curve of Spee," the radius of the circle on which this curve is superinscribed is longer or shorter in direct proportion to the length of the cusps and the depth of the overbite, i.e., a long or deep overbite indicates a curve of Spee inscribed on the circumference of a circle with a short radius, * Chas. W. Turner, The Human Dental Mechanism, page 220, Fig. 197. t Described by F. Graf V. Spee. DEVELOPMENT OF THE DENTAL ARCHES. 6lS and vice versa. Also, this radius is shortest in those cases in which the angle of inclination of the glenoid fossa is the greatest, and longer in proportion to the approach of the angle of inclination of the glenoid fossa, and hence the path of the condyles. to the horizontal. The abnormal variation of the "curve of Spee" in certain types of malocclusion is sufficient evidence of the importance of giving it due Fig. 456. consideration in the diagnosis and treatment of malocclusion, cases of which will be later described. INormal Development of Associated Anatomical Structures of the Internal Face. — In order that a clearer idea of the field of the orthodontist may be engendered, a study of the internal facial anatomy- from a vertical transverse bilateral section of the head, as shown in one of Dr. Cryer's dissections, Fig. 457, revealing comparatively normal development of the maxillary arches and associated structures and sinuses, may serve to illustrate how closely the internal structures are associated, and to what extent they are interdependent for normal growth and function. Immediately above the floor of the hard palate may be observed a straight nasal septum, dividing the internal nose into two large and well formed meati, adjacent to which, the fully developed maxillary sinuses are situated. This normal and proportionate development of associated anatom- ical structures of the internal face is not a chance coincidence, but the result of a functional and structural relationship which is most im- portant to the diagnostician. First in importance in the development of these associated struc- tiu^es of the mouth and nose is the function of mastication, the natural action and reaction of the teeth of the mandible against those of the maxilla assisting in the development of the dental and maxillary 6i6 ORTHODONTIA. arches, and thereby in the development of the floor of the nose and associated sinuses etc. Second in importance in the development of the dental and maxil- laryarches is the function of normal nasal breathing, which is only possible with properly developed nasal meati. Abnormal breathing disturbs normal developmental functions, be- cause with deficient respiratory powers, as in the mouth-breather, the Fig. 457. {Cryer.) teeth seldom come into contact sufficiently to obtain the requisite amount of occlusion and articulation necessary for proper development of the arches. Co-ordination of Functions. — It will be apparent, therefore, that co-ordination of the normal functions of respiration and occlusion is the most potent factor in the symmetrical and proportionate develop- ment of the internal face, the nasal cavities and associated sinuses, and the maxillary and dental arches. Such symmetrical development of related parts implies as well the existence of full nutrition, and the absence of any untoward etiological SYMMETRY AND ASYMMETRY OF THE FACE. 617 factors which would tend to diminish functional influence or lower the vitality in any way. Any local functional and developmental disturbance may be the result of general systemic conditions, of lowered vitality from what- ever cause, so that any local pathological manifestation in diminished or perverted function and consequent modified anatomical structures should be considered in relation to the health of the whole organism. The association of nasal stenosis, mouth-breathing, arrested de- velopment of the maxillae, and dental malocclusion, is sufficient evi- dence of the interdependence of function and structure in these associ- ated regions to convince the most skeptical of the importance of the study of the pathological anatomy of the internal face with a view to the discovery of certain causative factors, which through treatment will assist in the remedy or cure of abnormal developmental conditions requiring an intelligent differential diagnosis. It is primarily, then, upon the structural continuity of the maxillary arches with the structures of the nose, and upon the contiguity of the internal sinuses, as well as upon the correlation of the functions of occlusion and respiration, that the possibility of influencing develop- ment and restoring function in these correlated parts of the face is based. These several relationships will be further considered in the chapter on etiology. PART II. SYMMETRY AND ASYMMETRY OF THE FACE. Dento-facial Orthopedia.* — Orthodontia has advanced beyond the teachings which its name might imply into the field of orthopedia to such an extent that there can scarcely be any orthodontic treatment which does not include orthopedic considerations. The restoration of esthetic facial contour through orthodontic and orthopedic treatment, although included in the field of orthodontia, may correctly be desig- nated dento-facial orthopedia, and be defined as follows: Dento-facial Orthopedia is the art of restoration of facial sym- metry through the correction of abnormal development of the dental and maxillary arches, and dental malocclusion. Physical Relations of Beauty. — The broadening of the field of orthodontia to embrace the field of facial orthopedia has necessitated a closer study of the art relations of the human face with a view of ascer- taining those qualities of beauty which are related to the normal and * Term coined by Desirabode. 6l8 ORTHODONTIA. typical in development, rather than those qualities of facial beauty which appeal to the esthetic faculties alone. Beauty is defined as "the assemblage of graces or properties which are pleasing to the eye, the ear, the intellect, the esthetic faculty, or the moral sense," or as "the multiplicity of symmetrical parts uniting in a consistent whole." It has been pointed out by artists that no fixed "line of harmony" exists in relation to the profile, but that beauty of the face consists in a proper balance of the features according to type. Limited, then, as the science of orthodontia is, to a consideration of the physical relations of certain definite parts of the face, the qualities of symmetry and proportion alone, as indicated by the normal and harmonious development of the face as a whole, including the under- lying osseous structures as well as the muscular tissues overlying them, can be consistently studied in the determination of the normal or abnormal relations of these structures. Facial Types. — The facial orthopedist should never lose sight of the fact that there are a great many types of faces, varying with nationality, climate and environment, and that the features con- form with great persistency to racial characteristics in particular. Area of Dento-facial Inharmony. — ^The area of dento-facial inharmony is chiefly included in the zone of the lower third of the face (Fig. 458), extending a slight distance above the lower border of the nasal cartilage (a) to the bottom of the chin / {b), and from this point to the external ear {h). feIn the simpler cases of malocclusion asso- (0\ ciated with facial asymmetry the area of ^w;^ facial inharmony is included between the J horizontal lines ce and df, as in cases of a \ slight arrest of full development of the dental .jk arches. Some of the more complex cases of mesial, distal, supra-, and infra-occlusion in- FiG. 458. ' ' r ' volve not only this area but also the zone m- cluded in the triangle abh. The distance from the nose to the symphysis of the chin in some cases is often less than normal and infrequently greater than normal. For example, in Fig. 459 this distance is less than it should be normally because of the infra-occlusion of the molars and bicuspids, as is frequently the case in this type of dento-facial de- formity. In Fig, 460 on account of the loss of a number of the teeth by extraction the distance from the nose to the chin is less than normal. SYMMETRY AND ASYMMETRY OF THE FACE 619 In Fig. 461 the distance from the nose to the point of the chin is abnormally long, due to abnormal development of the mandible in connection with infra-occlusion of the incisors, cuspids and bicuspids. In some instances, the abnormal development of the mandible has been so great that orthodontic treatment is barely practicable, and operative surgery of doubtful benefit. A case of this nature is shown in Fig. 462. -Fig. 459. Fig. 460. Facial Symmetry consists of the normal and proportionate develop- ment of facial contour primarily dependent upon the corresponding develop- ment and function of the underlying osseous structures and sinuses. Symmetrical Measurements of the Facial Profile. — ^Viewed from the standpoint of the artist, the harmony of proportions of the profile consists in a balance of the features as shown by a correspondence in measurement of prominent divisions of the profile from the top of the head to the chin; from the hair to the bottom of the chin should measure \ ^ Fig. 461 Fig. 462. three-quarters of the height of the whole head; the forehead to the root of the nose measures one-fourth; the nose one-fourth, and the mouth and chin one-fourth. A very comprehensive illustration of these measurements may be seen in Fig. 463, in which at the same time may be noted the correspondence of the facial curves of the forehead, nose and chin, and the normal development of each separate third of the face so that a proper balance of the face as a whole is attained. 620 ORTHODONTIA. Fig 463. Fig. 464. For the full development of the lower two-thirds of the face, there must not only be perfect function in the respiratory mechanism, result- ing in normal nasal breathing and development of the whole middle third of the face, but there must also be proper functional activity in mastication, and the absence of any untoward influence in tooth or arch development. In Fig. 464 the models of the teeth of the young lady, whose profile is shown in Fig. 463, exhibit likewise a conforma- tion to the normal in occlusal relations and development of the dental arches as might be expected in a profile as well balanced. A very well-proportioned profile with a correspondence of curves of the forehead, nose, lips and chin, is illustrated in Fig. 465. Accord- ing to the principles of facial symmetry, it would be expected that SYMMETRY AND ASYMMETRY OF THE FACE. 621 the functions of respiration and mastication were unimpaired in this, individual in order to have produced the correlation of symmetrical parts of the profile as seen in the illustration. The middle third of the face is well developed, the nostril wide and dilated, and there was no indication upon examination of any nasal obstruction or inflammation which might induce a diminution of the normal breathing function. The proportions of the lower third of the face are also so perfect that the diagnosis of almost perfect development of the arches of teeth and the absence of any marked malocclusion might be made with a degree of certainty, and upon examination of the model of the mouth in Fig. 465. Fig. 466. Fig. 466, the correctness of this diagnosis may be seen, there being but very slight deviation from the normal relationship of occlusion. The observance of this interrelationship between normally de- veloped dental arches and well-balanced profiles led to the estab- lishment of the following principle in orthodontia, "the best balance, the best harmony, the best proportions of the mouth in its relations to the other features require that there shall be the full complement of teeth, and that each tooth shall be made to occupy its normal position — normal occlusion" (Angle). Relations of External and Internal Anatomy. — A very in- teresting illustration of the relation of external and internal facial development may be observed in a sagittal section of a typical skull, Fig. 467, made by Cryer. The profile appears proportionate in the 622 ORTHODONTIA. development of its various divisions, and a vievi^ of the internal anatomy reveals well-developed osseous structures and sinuses in the middle third of the face, and a typically normal development of the maxilla and mandible, and a tongue which almost completely fills the oral cavity. Cryer has demonstrated by many sections of the frozen heads of l-lG. 467. {Cryer.) cadavers that variation of the internal anatomy of the face and head is of such frequent occurrence that typical and syirmetrical develop- ment of the corresponding osseous structures and sinuses of the two lateral halves of the head is the exception rather than the rule, thus accounting in part for such distinctly noticeable variation in develop- ment of the superficial muscular and other tissues. SYMMETRY AND ASYMMETRY OF THE FACE. 623 Facial Asymmetry consists of the abnormal and disproportionate development of the contour of the face, dependent primarily upon a cor- responding abnormal development and growth of the underlying osseous structures and sinuses. In the consideration of facia! asymmetry, as related to dental arch development, it is necessary to exclude the facial defects caused by such nen^ous lesions as paralysis, or the structural lesions of tumors, and other similar pathological manifestations not bearing directly upon the general laws of facial development, except such develop- mental neuroses as are admitted to be embryonic in character, and which, whether degenerative or not, must be taken into consideration by the diagnostician of structural deformities in any part of the body. Measurement of Facial Asymmetry. — ^The screen method of measuring the face, illustrated in Fig. 468, affords a means of de- termining the variations in height of the corresponding halves of the face, and also the variation from symmetry of the facial thirds, and the anatomical deviation from the central facial line. In this illustration the right eye and ear are observed to be considerably lower than the left eye and ear, and the central line of the chin does not coincide with the central line of the rest of the face. Inharmony of the Profile. — A face may be perfect in its type ex- cept for some slight deformity in the lower third which may exhibit lack of harmonious development. For example, in Fig. 469, the profile conforms in most of its lines to its type, and contains many of the elements of beauty in some of its proportions, but the apparent promi- nence of the lower lip offsets all the esthetic characteristics of the other parts of the face. A study of this profile will convince the careful ob- server that the apparent deformity or protrusion of the lower lip and of the mandible is an optical illusion, and that the upper lip alone is out of harmony with the rest of the profile, being retruded from the normal pose which it should occupy. As proof of this diagnosis, a study of the occlusal relations of the Fig. 468. (Parke Lewis.) 264 ORTHODONTIA. arches of teeth in Fig. 474 exhibits a normal relationship in the molar region, and an abnormal position of the upper anterior teeth alone, they being in lingual occlusion. Fig. 469. Deformities of this nature often affect the welfare and happiness of the unfortunate possessors for a whole lifetime, so keenly sensitive Fig. 470. are they to public notice and unfavorable comment by those with whom they come into daily contact. Any variation from normal and symmetrical development of the two sides of the face may be detected by the use of the measuring screen ETIOLOGY. 625 or by drawing an imaginary line through the center of the face from the forehead to the chin, as in Fig. 471, in which a marked deviation from this line is noticed in the lower third of the face, and caused by the malocclusion of the teeth, which forced the mandible to one side. An examination of the profile of this case, Fig. 472, exhibits the extent of the deformity, the chin being considerably protruded, giving the individual a senile appearance. The model of the mouth of this young lady in Fig. 695 exhibits just such a lack of harmony in occlusion as one would expect from a study of the facial inharmony. Fig. 471. Fig. 472. The functions of speech and mastication are seriously impaired, and were it not for the skill of the orthodontist, there would be no alleviation of the deformed condition which is such a handicap to the one having such a facial disfigurement. PART III. ETIOLOGY. Deductions From Early Symptoms of Developing Malocclu- sion. — The establishment of diagnostic interpretations from the basis of occlusion has caused an earnest study of early symptoms of develop- ing malocclusion, a very large percentage of cases exhibiting such pecu- liarities of maldevelopment of the arches as a whole, as to claim a most serious consideration of the possible etiological characteristics, 40 626 ORTHODONTIA. and their probable bearing upon operative treatment of abnormal conditions present. The exclusion of many local etiological factors in the production of small and crowded arches of teeth has led to the conclusion that malpositions of the teeth, individually and collectively, are but super-- ficial symptoms of deficient or arrested function and development of the arches as a whole, including the alveolar process and underlying bone, and even extending into the associated nasal structures and sinuses. The concomitant arrest of development of the nasal cavities, and a diagnosis of similar local or remote etiological factors, furnishes the strongest proof of the wisdom of observing and preventing abnor- malities in development during the earliest period of child life, when functional insufficiency interferes most profoundly with the normal growth of developing anatomical structures. Very marked malocclusions of the deciduous teeth, such as pro- nounced protrusions, have been not infrequently observed by the author and others in children of two years of age and younger, exhibit- ing some form of functional derangement, especially in the nose and throat, and indicating defects in development which may be of congen- ital origin. These disturbances in development occur very early in life, and if remedial treatment is not instituted before the sixth or seventh year, or even earlier in some cases, the possibility of permanent benefit, especially in the establishment of normal nasal respiration, where it is perverted, is greatly lessened. Intra-uterine Influences upon Arch Development. — The normal development of the dental arch, including the alveolar proc- ess and the deciduous and permanent teeth, preconceives primarily, the healthy structure and the molding and development of the maxilla and mandible during embryonic life, which are naturally dependent upon the nutritive and other conditions present in intra-uterine life. It is conceded that prenatal influences, whether they be of a nutri- tional, functional or nervous type, have a definite bearing upon the metabolic processes which tend toward symmetry or asymmetry of development of the embryo in whole or part. Hare-lip and cleft palate are recognized as simply lack of com- plete development in the embryo through some retardation in intra- uterine development, the causes for which are obscure only because of the inability to directly trace the particular influences which might arise from a neurotic or other tendency, which in turn affects the ETIOLOGY. 627 growth and development of cellular structures in those parts of the human organism peculiarly open to such influences. Talbot remarks: "The structures of the mouth and nose being exceedingly variable in evolution, and the structures of the jaws and teeth having taken an embryonic trend for the benefit of the body as a whole, under the law of economy of growth, disturbances of balance are peculiarly apt to occur here." "Not only is actual growth upset by the operation of this disturbance of balance, but certain poten- tialities are likewise interfered with." Whatever the particular stress may be which lowers potentiality or retards development in the embryo, it is enough to know that such influences exist, and invariably affect the development of particular parts of the organism in greater or lesser degree. Hellman* remarks, "If we should examine the countless modifica- tions that a developing organism passes through from inception to parturition, and realize the underlying conditions bringing about these remarkable transformations, until the completion of an individual, we shall not wonder that a malformation may appear now and then, but we shall be surprised that such disturbances are not the rule instead of the exception." This writer calls special attention to Ballantyne'sf charting of the periods of ante- and post-natal development with reference to the par- ticular form of interference with developmental conditions which may ensue during each period. Post-natal Factors in Arch Development.— After birth the nor- mal development of the dental arch is largely a question of proper nutrition and function, recognizing also, the possibility of an insuffi- ciency of nutrition and perversion of function with which the child may be born into the world, and from which inadequate foundation, normal function and normal structure are not readily developed. Heredity and Environment. — Just at this point it may be necessary to distinguish between the influences of heredity and environment, in order that a clearer conception of the two may be engendered. Quoting from Brady: J "The tendency to resemble ancestry is called heredity, and a character or condition that appears prominently through a series of generations is said to be hereditary or inherited. The surroundings of an organism are called its environment, and include * Hellman, Some Etiological Factors of Malocclusion, Dental Cosmos, Sept., 1912, p. 02. t Ballantyne, Manual of Antenatal Pathology and Hygiene. X The Influence of Heredity on Malocclusion. 628 ORTHODONTIA. every possible condition which might have any effect upon its devel- opment, such as food, climate, light, air, moisture, heat, cold, cultiva- tion, artificial benefits, natural enemies, companionship, mental con- dition, method of living, exercise, in fact, any and all things capable of exerting any influence for better or worse." " Heredity is the force that holds all life to its true forms throughout the ages, and its power is not set aside in a few years even under an intensely changeable environment." "Heredity always tends to promote the normal, the healthful, not the abnormal or diseased." "Aside from the fact that heredity promotes the normal instead of the abnormal, it is also very questionable if a feature like mal- occlusion can be transmitted at all. A violent change is much less likely to be transmitted than a slight one, and a bad case of mal- occlusion is certainly a great change from the normal. Weismann, the great writer on heredity, gives it as his opinion after years of observa- tion that only slight acquired conditions are ever transmitted, and scientists are very cautious as to their statements of what changes may become hereditary and what may not." "If a similar condition exists in parent and child, let us not jump to the conclusion that the defect is inherited, but rather let us in- vestigate the environment. If we find contracted dental arches in the same family it is a sign that all members have lived upon the same kind of food, and all have failed to give normal exercise to the teeth and jaws. If nasal or pharyngeal hypertrophies exist from one genera- tion to another, we will find the environment is inherited rather than the disease." Relations of Internal Secretory Organs to Malocclusion. — Recent investigations have shown that the entire chain of internal secretory organs, or ductless glands, are intimately connected with the growth of the whole body. Biedl* remarks: " The results of human pathology, especially the comparison of the clinical with the post-mortem findings, have in other directions supplied the most valuable evidence in favor of the doctrine of internal secretion. Instances are afforded by myxedema on the one hand, and by exophthalmic goiter and acro- megaly on the other. These pathological conditions have supplied facts concerning the physiology of the thyroid and pituitary glands, the value of which is incalculable." Acromegaly, which is a chronic disease characterized by overgrowth or enlargement of the bones and soft parts of the hands, feet, and face * Biedl, Internal Secretory Organs. ETIOLOGY. 629 furnishes a clinical picture of the results of hypertrophy of the pituitary body, or with disease of the thyroid. Cretinism, associated with thyroid disease, on the contrary, exhibits the inhibitory action on body growth as shown in dwarfing of the stature, idiocy, and mental dullness. Gushing* suggests that "There are few subjects in medicine which promise a wider overlap upon the field of special workers than hypophy- seal pituitary) disease." Thus it is that " in view of a new pathology based upon a new physiology, which recognizes the internal secretory organs," as Grieves expresses it, the etiology of such maldevelopmental conditions as malocclusion and facial deformity should include the possible effects of disease or insufiQciency of these ductless glands. In a summary of the investigations and clinical studies of the internal secretory organs, Grievesf has pointed out the rational theory of such an etiology of malocclusion and facial deformity, through the cor- relation between the physiological and pathological functions of these glands. He says, "that all of these tissues (the central and sympathetic nervous systems) and glands (the internal secretory) compensate and inhibit each other in cycle, any interfering influence or disease which disturbs this co-ordination seriously and very diversely affects nutri- tion, bodily development and function according to the time at which it occurs, before or after puberty, with the most marked effects at the periods of bodily stress and change, i.e., from birth to tooth eruption, the first and second dentitions, puberty and menstruation; pregnancy and lactation in the female, climacteric and senility in both sexes; that the internal secretory organs have each a special function in these important periods besides that of growth, presiding over paTturition,, controlling sex and sex characteristics, promoting lactation and main- taining immunity to infectious diseases in the infant, and all of this cycle is peculiarly susceptible to damage from the infectious diseases of child- hood, as scarlet fever, measles, chickenpox, whooping cough, etc." Also, "that normal development of the bones of the face and the base of the skull, the proper growth and articulation of these with the base of the skull, the growth of the nasal and post-nasal regions and accessory sinuses, and the eruption of the teeth, all depend upon the correct functioning of these organs and their correlation with the sym- pathetic nervous system, insufficiency or disease in any one, will interfere with the synchronism of the whole, causing various forms of deformity, * Gushing, The Pituitary Body and its Disorders, t Grieves, The Relation of the Internal Secretory Organs to Malocclusion, Fadal Deformity, and Dental Disease, Dental Cosmos, Aug., 1914. 630 ORTHODONTIA. as in the major expression, for instance, thyroid disease producing cretinism and myxedema, and pituitary disease producing acromegaly and giantism, all afifecting facial regions, as in minor expression, glandular insufficiency producing the different forms of malocclusion and defects in the teeth and their eruption." Grieves further points out that breast feeding by supplying activators or stimulants to action to the ductless glands has its ratio of influence in bodily growth, and bottle feeding, in its lack of supply of these same activators, has a corresponding reverse influence in inhibiting the action of these glands and retarding development, not only of the whole body, but especially of the teeth and jaws, and facial bones. Thyroid insufficiency and hypopituitarism represent enough of the derangement of function of two of these glands and consequent malde- velopment of the body so that the less known pathology of the thymus, the suprarenals, the spleen, and other ductless glands may well be con- sidered with a view to throwing further light on the etiology of such peculiar conditions of maldevelopment as present to the orthodontist. Functional Influences. — After birth, the influences which tend to normal arch development are largely functional, influenced of course by environment. Succeeding mammary function, which is believed to have consider- able influence upon general developmental conditions in infancy, the function of mastication, and the proper use of the muscles of the tongue, cheeks and lips, are the most important factors in the development of the dental arch after dentition is complete. The exclusion of other factors which would tend to retard development, such as anemia in- fluenced by malnutrition, and other constitutional conditions, and the absence of nasal or post-nasal obstruction to normal breathing, are essential to the normal growth of maxillary structures and the proper sequence of functions. Normal Muscular Action. — As illustrative of the effect of normal muscular action upon the development of bone in the maxilla and mandible, the lines of stress in developing bone caused by muscular action as seen with the X-ray by Walkhoff, offer sufficient evidence of the influence of muscular action in development, not only in embryo and infancy, but also during the entire period of development of the dental arches up to the time of the eruption of the last permanent tooth. This investigator has demonstrated conclusively that the stress upon the surface of the bone through the muscular attachments was directly related to the internal development of and arrangement of ETIOLOGY. 631 the bone spicules, which form themselves in lines parallel to the direc- tion of the exertion of the muscular force upon the external surface of the bone. Disuse 0} the muscles 0} mastication, or their abnormal use, therefore, must have its efifect in the deficiency and abnormality of development in the dental arches. The disappearance of the angle formed by the rami and body of the mandible in certain pronounced mouth-breathers of Class III is an evidence of the influence of abnormal muscular action uppn the shape of the underlying bone. Inflammatory Changes in Alveolar Tissues.— The thickening and hardening of the cancellated and cortical portions of the alveolar process through suppurative conditions caused by diseased teeth in- terferes with normal and uniform development of the bony tissues in which these changes take place, and no doubt is causative of some of the peculiarities of development of the dental arches, especially of tooth impaction. Tooth-sacs of Permanent Teeth ^''^^^ ■^_ ^_^a: ^^^ M %^^£* is. / ■ ^ wt^"^^ f '^*Vr ^; wnf^^sm^ 1 . . Tooth-sacs of Deciduoiis Teeth Periosteum of Hard Palate Fig. 473. — Tooth-follicles for deciduous and permanent teeth, three months after birth. (Broomell.) Disease. — The influence of such diseases as rickets, syphilis, and others may seriously affect the development of the osseous structures of the maxillae. Malocclusion is often a result of pyorrhea, the teeth becoming elongated, and forced into malpositions through the undue influence of their own inclined planes. Abnormal Arch Development. — In consideration of the factors in dental arch development which have been stated, it is interesting to note the positions of the permanent tooth follicles at a period in child life when the deciduous teeth are unerupted, and speculate upon 632 ORTHODONTIA. the possibilities of arrested development upon the permanent arches of teeth. Fig. 474. Fig. 475- Fig. 473 represents the dissected tooth follicles of the deciduous and permanent teeth in the mouth of a child three months after birth, the ETIOLOGY. 633 plastic tissues in the center of the cut being the periosteum covering the hard palate, the tooth follicles being imbedded and firmly adherent to the fibrous tissues laterally and anteriorly. The tooth sacs of the deciduous teeth are upon the periphery, being external to, and larger than the sacs of the permanent teeth. The arch of the deciduous teeth, which are nearly ready for eruption anteriorly, is very nearly uniform in shape and development, while that of the permanent teeth has not at this age even assumed any definite- ness in the uniformity or position of its teeth, the four permanent in- cisors being more fully developed than the cuspids and bicuspids, but the lingual position of the laterals indicates that considerable Fig. 476. Fig. 477. arch development must take place before there will be sufficient space for these teeth to erupt into their normal positions in line with the centrals. If, by reason of any infantile cachexia, such as malnutrition, from whatever cause, arrest of arch development should occur at this age, or even later up to five or six years of age, the resultant effect upon the arch of the permanent teeth might be such as is illustrated in the two casts shown in Figs. 474 and 475 at the ages of seven and twenty-seven, in which the positions of the central and lateral incisors are seen to be almost identical with those of the permanent incisor follicles in Fig. 473- It will be observed that the adult arch in Fig. 475 did not develop 634 ORTHODONTIA. any larger than the arch of the deciduous teeth in Fig. 474, the arrest of development being almost permanent except for the eruption of the permanent teeth into positions of irregularity, so great was Fig. 478. the functional disturbance which left its impress upon the maxilla and overlying processes. Another interesting feature about the case of this adult is that there was no apparent facial deformity except the slightly marked deviation of the central facial line at the age of four, see Fig. 476, ETIOLOGY, 635 but at the age of twenty-seven, Fig. 477, the distortion of the facial lines indicates serious malocclusion and maldevelopment. Again, in Fig. 478, is observed the upper deciduous arch of a four year old child, and the undeveloped upper arch of a ten year old child.* The feature of striking interest in the case is the fact that the arch of the ten year old child is scarcely larger and is not more developed than that of the child of four with which it is compared. Such studies as these prove to the observer that, although the func- FiG. 479. tion of occlusion is perverted, and its beneficial influence upon the growth of the dental arches lacking, there are still present causative factors of the arrested development, of either prenatal or post-natal origin, which must be given due consideration. ^Mouth-breathing. — One of the most serious abnormal conditions with which the rhinologist and the orthodontist have to deal, and one as intimately connected with the disturbance of normal function and structure in the field of the one as in that of the other, is the partial or complete loss of normal respiratory function through the obstruction of the nasal, naso-pharyngeal, and oro-pharyngeal air passages, causing oral respiration, commonly known as mouth-breathing. That this condition, with all of its injurious results upon the de- 636 ORTHODONTIA. velopment of the bones of the head and face, the disfiguring of the features, and the undermining of the general heaUh, is becoming more prevalent, one hardly needs statistics to show, in view of the great numbers of those afflicted with this trouble in all walks of life. Fig. 479 represents the face mask of a typical mouth-breather, the characteristic features noticeable being the open and drooping mouth, the short upper lip, the undeveloped nose and undilated nos- tril, and the malocclusion of the teeth. The vacant stare especially accompanies the presence of large ade- noids, and is said to be caused chiefly by the stagnation of lymph at the base of the skull. On examination of the relations of the arches of teeth (Fig. 480) Fig. 480. Fig. 481. of the patient whose face mask is illustrated in the previous figure, it will be noticed that arrested and abnormal development of the arches of teeth is in evidence, sufficient to cause a very great lack of|harmony of the facial lines. The upper arch is narrow and elon- gated, the upper bicuspids and molars being in lingual occlusion,, and the lower arch distal to its normal position, a case of the first division of Class II, Angle's classification. It has been the observation of the author that a mouth-breather may present a malocclusion of any one of the different classes into which it is possible to divide the abnormal relations of occlusion, rather than of only one or two of them, as has been suggested by some writers. The shapes of the arches of teeth are varied, also, and the extent of the mal- occlusion measured somewhat by the degree to which oral respiration is resorted to. One of the most aggravating forms of malocclusion associated witb ETIOLOGY. 637 mouth-breathing is that of the "open-bite" malocclusion, as it has been termed by some writers. Lack of anterior occlusion and "infra- occlusion" are similar designations for the same condition. Fig. 481 illustrates such a case belonging to Class I. There is a noticeable lack of development of both arches in this case, there being insufficient growth for the eruption of the per- manent teeth, especially in the incisor region. Fig. 482 exhibits a very com- mon form of malocclusion, of Class II, Div. i, found among mouth-breathers, the lower arch being distal to normal in occlusion, and the shortness of the upper lip, and therefore lack of function in supporting the incisors, allowing them to protrude to a considerable extent, a con- dition which is intensified by the lower lip adjusting itself between the upper and lower incisors and forcing the upper incisors still Fig. 482. Fig. 4S3. Fig. 484. farther, forward, and further aggravated by the wrong tension of the muscles of the upper lip over the canine region. The elongation of the upper incisors from non-support of the lower incisors follows, and the articular motions of the mandible still farther extends the protrusion of the upper incisors. A very similar in- harmony of occlusion of the anterior teeth and disfigurement of facial lines is often seen in the protrusion"^ of Class I. 638 ORTHODONTIA. It is believed that the distal position of the lower arch in cases of this class is caused primarily by the lack of lateral development of the upper arch, because expansion of the upper arch in the early treatment of these cases often restores the normal relations of occlusion in the molar region, by allowing a farther forward position of the mandible without cusp interference. Figs. 483 and 484 represent a mouth-breather at the ages of six months and seven years respectively, and it will be noted that the open and drooping mouth and other symptoms are plainly noticeable in both pictures, showing that the mouth-breathing was of early origin, and had persisted and become more aggravated in its symptoms as the child grew older. The casts of the child's teeth in occlusion in Fig. 485 exhibit a maloc- clusion of Class II, Div. i (Angle). Both arches are contracted and un- FiG. 485 developed, there being insufficient space for the eruption of the upper and lower lateral incisors, and in addition, the lack of anterior occlusion. Mouth-breathing is usually regarded as a habit, but in reality is a necessity, because of the inability to breathe properly through the nose, there being a lack of development of full nasal space, or inflammatory conditions, or some impediment in the nasal tract which will not allow sufficient air to pass through. Obstructions to Nasal Breathing. — Among the various obstruc- tions to nasal breathing may be mentioned deflection of the nasal septum, hypertrophied tonsils and turbinate bones, adenoids, and the diseased conditions resulting from syphilis, tumors, polypi, and cysts. "If the nasal and post-nasal passages are unobstructed, every inspiration empties the ethmoid veins and through them the longi- ETIOLOGY. 639 tudinal sinus and cavernous plexus. When there is obstruction to nasal respiration, the circulation at the base of the skull is interfered with, and a long train of ills brought about which interferes very greatly with the health of the individual. In the first place, the quantity of air aspirated through the mouth in a case of nasal obstruction is not equal to that of normal nasal respiration, and the system suffers from lack of sufficient oxygenation" (Griinwald). Ziem's experiments in producing nasal stenosis in young animals by occluding one-half of the nose artificially, with the result of the asymmetrical development of the two sides of the nose and adjacent bony tissues, the obstructed half being arrested in development, as well as the contiguous tissues on that side of the face, are worthy of Fig. 486. note as proof of the correctness of the theory that nasal obstruction is causative of arrest of development in the human head and face. It is important that the diagnosis of the obstruction of the air passages should be made as early as possible after its incipiency, so that by proper treatment and operation, if necessary, normal develop- ment may not be more seriously interfered with, and the health of the child seriously impaired. There are so many local symptoms of this abnormal condition that even the novice ought to be able to diagnose it. Vocalization is impaired, especially in the pronunciation of the 640 ORTHODONTIA. letters m and n, which, in the muffled voice of the mouth-breather sound like b. A persistent catarrhal condition, often mistaken by parents for an ordinary cold, together with an unusual dryness of the pharyngeal mucous membrane, and the continued drooping open of the mouth, ought to give warning of the beginning of serious nasal obstruction. If allowed to continue, deficient nasai respiration may be causa- tive of arrested development, not only in the face and head, but in other parts of the body, insufficient oxygenation causing anemic conditions of the general system, the dulling of the mental faculties, and a favor- able opportunity for the inception of infectious diseases, especially tuberculosis. Deviation of Nasal Septum. — In the normal subject the nasal septum occupies a position in the nasal cavity dividing one-half of the nose from the other. Slight deviations are frequently seen in people who are not troubled with nasal stenosis to any degree, but where there is an extensive devia- tion from the median line, oc- clusion of the side toward which the deviation takes place occurs, with consequent deficient nasal and enforced mouth-breathing. Fig. 457 illustrates a skull sec- tion (from Cryer) in which the nasal septum is in its normal median position, the choanae on each side being equal in size. Fig. 486 portrays a marked deviation of the septum to the right. The choana on the side toward which the septum is de- flected is very much smaller than the other, and must have been almost completely occluded dur- ing life, and there is every reason to believe that the subject was a mouth-breather. Operations for the straightening or partial removal of the septum when deflected, are of common occurrence, and are usually followed by immediate relief in cases of deficient nasal respiration. Hypertrophy of Faucial Tonsil. — Another cause of nasal stenosis is the hypertrophy of the faucial tonsils, and from the Fig. 487. ETIOLOGY. 641 frequency with which operations for their removal are performed, their diseased condition and obstruction to nasal breathing cannot be judged uncommon. The faucial tonsils are frequently the seat of infection and disease because of a hypertrophied condition and improper per- formance of function. The large globular masses of tissue in Fig. 487 are the faucial tonsils removed from the throat of a two year old child, and are so hypertrophied that they nearly occluded the throat. Hypertrophy of the turbinate bones, especially the inferior, is not an infrequent cause of nasal stenosis, and consequent mouth- breathing. Fig. 488 exhibits a portion of the inferior turbinate which was removed from the nose of a patient who was suffering from partial nasal stenosis. Adenoids. — One of the most common causes of mouth-breathing is found in the hypertrophy of the pharyngeal, or Luschka's tonsil, which Fig. 488. Fig. 489. is situated in the vault of the naso-pharynx, usually just out of sight above the uvula. A mass of this enlarged glandular tissue may be seen in Fig. 489, being a posterior rhinoscopic view of the naso-pharynx, and it can be readily understood that the naso-pharyngeal passages may become partially occluded by the downward growth of this tissue. Parke Lewis has called attention to the possibility of impairment of function of nutritive vessels passing through the carotid canal 41 642 ORTHODONTIA. (which bears the carotid artery, the superior cervical sympathetic and the lymphatics) through the pressure of adventitious growths in the naso-pharynx upon the tissues which pass through the foramen lacerum medium, which is immediately above the site occupied by the adenoid tissues, and which opens into the carotid canal. The conclusions of Parke Lewis are based upon those of Sajous in regard to the control of all oxygenation processes in the body through the pituitary bodies, which are very closely associated with the nutrient vessels passing through the carotid canal. Sajous' Theory. —Sajous indicates the significance of these organs and their physiological and pathological importance in this connection as follows: "It will be apparent that any lesion capable of blocking the afferent and efferent impulses that traverse it at all times, and Fig. 490. which represent the aggregate of the organism, inciting and governing energy, must necessarily compromise life, or the functions of an organ to which the blocked nerves are distributed." "The large mortality under chloroform in adenectomy is in all probability due to the shock conveyed to the posterior pituitary body through the foramen lacerum medium immediately over the lymphatic enlargements." "It will readily be seen, therefore, that whatever interferes with the nutritive functions at the vault of the pharynx may disturb the subsequent development of the whole skull and its contents." ETIOLOGY. 643 The very close relationship which exists between the tissues of the pharynx, and the nutritive vessels of the carotid canal may be seen from observation of the position and direction of the more nearly vertical of the two probes passing through the skull section in Fig. 488, it being passed through the foramen lacerum medium and emerging into the space occupied by the pituitary body. The inferior opening of the foramen lacerum medium is in the adenoid region, and the vessels which enter it are very apt to be impinged upon by hyper- trophy of the pharyngeal tonsils, and the nutrient and nerve supply to the pituitary bodies cut ofif enough to materially aflfect the proper performance of the functions of these organs, with consequent disturb- ance of development of the whole skull and its contents, as well as that of the entire organism. The horizontal probe in Fig. 490 passes through the optic foramen into the space occupied by the pituitary bodies, illustrating the very close relationship between the vessels of the eye and the pituitaries, and suggesting the probability of visual defects and insufficiencies from hypertrophied tissues in the naso-pharynx. Talbot,* in his work, also notes the possible influence of the pituitary body on the growth of the palate and of bone. He says, "In dealing with the development of the palate, both pre- and post-congenitally, the relations of the hypophysis, or pituitary body, have to be taken into account, since it has been well demonstrated that this body exerts an influence over body growth and the structures thereto related." . . . . " Strain on the development of the hypophysis after birth can not only produce undue growth of bone, but can also check development of it."* Removal of Adventitious Growths. — Granting that the theory of pressure from the impingement of adventitious growths in the pharynx upon the nutrient vessels and nerve supply of the pituitaries has not been really demonstrated, it would hardly seem to be necessary to argue the necessity of early treatment of malocclusion and the removal of all nasal and post-nasal obstructions to nasal lespiration, thus promot- ing normal developmental conditions before the period of normal and rapid growth has passed, and choosing the opportunity of greatest benefit to the patient. Irreparable damage may be done by the neglect to observe the early symptoms of nasal obstruction, and by the failure to place the patient in the hands of a competent rhinologist for operative treatment. * Talbot, Etiology of Cleft Falate, Sec. V, Page 195; Trans. Fourth Internat. Dental Congress. 644 ORTHODONTIA. The operation for the removal of post-nasal obstructions is a com- paratively slight one, some cases not even requiring the use of a general anesthetic, although, where the faucial tonsils as well as the adenoids are to be removed^ the more thorough surgery in this region is assured under general anesthesia. Fig. 491 represents a very characteristic expression of a mouth- breather of four years of age, who later, at the age of seven, was brought to the author for treatment of malocclusion. The segregated mass of tonsillar adenoid tissue shown in Fig. 492 was removed from the naso-pharynx of this patient by a rhinologist, before treatment of the malocclusion was instituted. Fig. 491. A diagnosis of the malocclusion revealed the mesial occlusion of the lower arch of teeth as seen in Fig. 691, and the restoration of the normal mesio-distal relations of the arches resulted in the change of occlusion noted in Fig. 692, the operation being performed entirely upon the deciduous teeth. The change in the appearance of the boy's face from the mouth-breather in Fig. 493, with his features all distorted in his efforts to close the mouth, to the calm, peaceful facial lines after the removal of these obstructing growths and correction of the malocclusion, in Fig. 494, indicates the advantage gained by early operating in this class of cases. ETIOLOGY. 645 The development of this face along normal lines of growth is now assured and there is nothing left undone to insure the very best Fig. 4g2. results in the restoration of facial harmony and normal respiration, and consequently the attainment of proper physical . development which in this case, was alreadv deficient. Fig. 493. Fig. 494. Mechanical assistance in holding the mouth closed after removal of nasal obstructions, and correction of malocclusion, such as the 646 ORTHODONTIA. wearing of head bandages and mouth plasters, is beneficial in the treatment. Irremediable harm is done by the oft repeated advice to "wait until the permanent teeth are all erupted before beginning operations for correction of malocclusion," and even greater damage may be done by the neglect to observe the early symptoms of nasal obstruction, and the immediate reference of the patient to a competent rhinologist for operative treatment. Deformed arches of teeth and disfigured features become confirmed in their abnormality after a long period of abnormal development, and neither the local tissues nor the general system will res[)ond to remedial measures to anything like the degree that they would had they been operated on at an early age. The head contains the portals of the human body, and it should be the duty of the orthodontist to guard against any ill effects to the health through the neglect of the oral cavity, its teeth, and related structures of nose and throat. Mouth-breathing, especially, should be prevented by such means as are at one's command, with the aid of the rhinologist, and the correction of such resulting defects in occlusion Fig 495- of the teeth and inharmony of the facial lines as may be necessary at the time the case presents with the symptoms of nasal stenosis. Local Factors in Malocclusion. — Among the local causes of malocclusion of the teeth may be mentioned; prolonged retention of deciduous teeth, premature loss of deciduous teeth, loss of permanent teeth, thumb-sucking and lip-biting, supernumeraries, and abnormal frenum labium. Prolonged Retention of Deciduous Teeth.— The retention of a deciduous tooth beyond the time for its natural Iqss through absorptioB ETIOLOGY. 647 of its roots forms a mechanical barrier to the normal eruption of its permanent successor, which is deflected labially, buccally, or lingually. The permanent central incisors in Fig. 495 were deflected lingually through the prolonged retention of the deciduous centrals, the roots of which did not absorb. As soon as these conditions are observed, the deciduous teeth which have been retained beyond the time for their natural loss should be extracted, and the permanent teeth which have been deflected, assisted into normal positions in the arch. Premature Loss of Deciduous Teeth. — One of the prolific secondary causes of malocclusion and lack of arch development is the premature loss of the deciduous teeth, especially of the incisors and cuspids. That the mechanical influence of the deciduous teeth in assisting in the development of the arch is a necessity up to the time when natural absorption of the roots of the deciduous teeth should take place, one has only to observe the contraction of the spaces occupied by prematurely lost deciduous teeth to readily understand. Fig. 496. An illustration of the retarded development caused by the pre- mature extraction of all deciduous teeth at eight years of age may be seen in Fig. 496. It is easy to prognosticate a serious malocclusion upon the eruption of the remaining permanent teeth. The loss of the approximal surfaces of the deciduous teeth by caries is also causative of lack of arch development through the loss of the mechanical influence of the deciduous teeth hi their entire mesio-distal diameters, and such carious conditions should be observed in their earliest stages and fillings inserted to restore full approximal contour. The loss of permanent teeth through extraction or disease, by de- stroying arch integrity is another frequent cause of malocclusion, which is considered under the heading, "The Problem of Extraction." 648 ORTHODONTIA. Thumb-sucking and Lip-biting. — The habits of thumb-sucking, lip and tongue biting are responsible for the inception of some maloc- clusions, and for the aggravation of a very great many cases, with other primary causative factors. Thumb-sucking is not as frequent a causative factor in malocclusion as is generally supposed, but that it does affect the development of the arch is certain. Usually, but one side of the mouth is aflfected, according to which thumb is used, although it is not uncommon to find that the thumb is held in the center of the mouth, protruding the upper central incisors. When the thumb is held on either side of the center, the upper incisors on the side in which the habit is induced are protruded. In Class I and II cases in which the upper incisors are protruded, the habit of biting the lower lip has a pernicious influence in increasing the extent of the malocclusion, and in some cases is believed to be the initial cause of the abnormal occlusal relations. The inculcation of a similar habit with the tongue is productive of more or less deviations from the normal in occlusal relations, and the observance of any of these habits by the parent or dentist should be followed by efforts on their part to overcome the habit and the damage already done. Prevention of Thumb-sucking. — A very practical method of preventing a child from sucking the thumb is to enclose its hands in Fig. 497- polished aluminum balls, such as is shown in Fig. 497, an attachment being made by a sleeve to the child's arm, and worn as much of the time as possible, especially at night, until the habit is broken up. The wearing of a simple apparatus of this kind will enable the child to use its arms, yet at the same time, prevent the possibility of getting the fingers or thumbs into the mouth, and is much more humane than tying the arms. The balls are ventilated by several small holes, and the sleeve and ball may be easily sterilized by boiling. Supernimierary Teeth.— Supernumerary teeth are occasionally found in the mouth, and are often of the peg-shaped variety shown in DIAGNOSIS. 649 Fig. 498, occasionally presenting with several irregular cusps, although sometimes resembling an adjacent normally developed tooth to such an extent that an X-ray diagnosis is necessary to differentiate between them. Their removal is usually indicated, and the restoration to normal position of the teeth which have been forced out of their alignment. Abnormal Frenum Labium. — The abnormal attachment of the frenum labium sometimes causes the separation of the upper central incisors, acting as a rubber cushion to force these two teeth apart. Cases of this character are somewhat difficult to treat, although operative measures are now seldom resorted to for the partial removal of the ligament. Fig. 49S. PART IV. DIAGNOSIS. General Considerations. — A thorough diagnosis of any case of malocclusion should include the observance of every pathological in- dication in the oral cavity and adjacent parts of the head and face, for only with a full understanding of the variations from normal con- ditions is it possible to produce the best results in treatment. If the deciduous teeth are present in part or whole, it should be noted whether they occupy their full mesio-distal space, and are assisting by their presence in the development of the arches. Their premature loss is usually indicated by a closing up of part or all of the space which they originally occupied, and indicates non-development. 650 ORTHODONTIA. A primary examination of the permanent denture should first deal directly with each individual arch, noting the absence of teeth, and their effect upon each arch, tracing minutely the changes incident to their removal in the contraction of the arch, and secondarily the effect upon the occlusion and articulation. Accurate plaster models should be made and the normal sizes of the arches determined by a method of arch pre-determination to be described. The case should be classified, and the variation of the facial lines from harmony should be studied in relation to the occlusion. The etiological characteristics in the case should be carefully considered, and an inquiry into the history and habits should, by exclusion, remove any doubt as to their signification in the case. Mouth-breathing, especially, will be readily detected from an observance of the distortion of the face and mouth peculiar to this pathological condition. The presence of enlarged tonsils may be easily seen with the tongue depressed slightly, and adenoids may be felt with the index finger carefully and quickly inserted into the throat above the uvulae. The examination for adenoids and deflected septa and other nasal obstructions should be made by the rhinologist as soon as there is any suspicious indication of there being such patho- logical conditions present in the case. The patient's general health should be inquired into, and the probable effect of any of the infectious diseases of childhood upon the development of the dental arches should be noted. As any diagnostic interpretation is of value only in so far as it is of use in prognosis, it will be recognized that the greatest benefits to be secured from treatment can only be assured by an intelligent percep- tion of all the etiological and pathological factors involved in the case, no one of which is so obscure as not to be considered. The history of the patient, with carefully outlined subjective and objective symptoms of pathological significance should be a matter of careful detail and should be recorded systemically for future reference in the treatment of the case. Fundamental Pathological Conditions in Malocclusion. — It has been pointed out by Lischer that four fundamental pathological conditions conjoin in malocclusion, viz., Malposition of the Teeth, Malrelation of the dental arches. Malformation of the jaws, and Malposi- tion of the Mandible. The first two of these fundamental pathological conditions are found separately and together, and form the basis of the Angle classification DIAGNOSIS. 651 of malocclusion, which has done admirable service as a "working classification" for the last fifteen years. As orthodontia develops, it may be necessary to provide a more extensive classification to include the jaw malformations and man- dibular malpositions, especially in view of the fact that the orthodontic or surgical treatment of some of these more complex pathological conditions has become more definitely established in a small percentage of favorable cases. Designation of Malpositions of Individual Teeth. — ^The nomenclature of Angle in designating the malpositions of individual teeth is based upon their deviation from the "line of ocdusion^^ which he defined "as being the line with which in form and position according to type, the teeth must be in harmony in normal occlusion^ According to this nomenclature, if a tooth is outside of this line it is in labial, or buccal occlusion; if inside of this line it is in lingual occlusion; if it is forward of this line, it is in mesial occlusion; if in the reverse direction, it is in distal occlusion; if rotated upon itself, in torso- occlusion; teeth which have been elongated beyond normal relations are in supra-occlusion; and those which are insufficiently elevated are in infra-occlusion. Malrelation of the Dental Arches. — ^Under this heading is in- cluded the mesio-distal variations of the dental arches, and is embodied in Angle's classification of malocclusion, which represents three distinct classes, and an occasionally found fourth class. Class I, Angle's Classification. — ^To the first class belong those cases of malocclusion which are characterized by normal mesio-distal relations of the dental arches, with contracted and undeveloped maxillary arches, especially in the anterior portion, in which the teeth often assume varied forms of individual malocclusion, and often simu- lating in this anterior region, the peculiarities of Classes II and III, both in the occlusion and facial deformity. Class II. — In the second class of malocclusion are placed all those cases in which the lower dental arch is distal to the upper on one or both lateral halves, having two divisions of bilateral distal occlusion, the first division being characterized by protruding upper incisors, usually mouth-breathers, and having a subdivision in which the distal occlu- sion is confined to one lateral half, the other half being in normal mesio-distal relations; the second division having retruded upper in- cisors, usually normal breathers, and its subdivision having the distal occlusion on one lateral half of the dental arches only. The facial profile of a case of the first division of Class II is usu- 652 ORTHODONTIA. ally diagnostic of the occlusal relations, the upper lip being short, and revealing the protruded upper incisors, and the receding chin indicat- ing the distal occlusion. As these cases are usually mouth-breathers, the characteristic open drooping mouth and peculiar tension of the facial muscles is a sure indication of naso-pharyngeal obstruction of present or previous date. The facial deformity is not so pronounced in the second division, the patients usually being normal breathers, the upper lip being of proper length, but the features disfigured by the receding chin and lower third of the face. Class III is characterized by a position of the lower arch which is mesial to the upper, with protruding lower incisors, having a division in which the mesial occlusion is bilateral and a subdivision in which the mesio-distal relation to the upper is normal in one lateral half of the lower arch and mesial to normal in the other. The facial profile is correspondingly deformed, the chin being prominent, the middle third of the face undeveloped, the angle of the rami of the mandible being more obtuse than normal, and, in some cases of long duration, there is scarcely any discernible angle between the point of the chin and the articular ends of the condyles. This class of cases would be included under the classification. Malformation of the Mandible. Mouth-breathing is frequently observed in Class III, and its exist- ence in any case serves to increase the inharmonious lines of the already deformed face. Class rV. — A very rare class, although found to exist in sufficient numbers to be worthy of record, and treatment, is Class IV, in which the occlusal relations of the dental arches present the peculiar condi- tion of being in distal occlusion upon one lateral half, and in mesial occlusion upon the other half of the mouth. As diagnostic of these various classes, the variation from the normal mesio-distal relations is usually best indicated by the relative mesio- distal relations of the upper and lower first permanent molars in occlusion, since they present a history of the longest lived occlusion during the ages in which malocclusion usually presents, and having such an important part in the building of the permanent dentition as to be appropriately styled "the bulwarks of the dental arches." Classification Chart. — In order that the principles upon which this classification is based may be the more readily understood, the author has arranged the three common classes and one rare class in comprehensive chart form in Fig. 499, the right and left lateral halves DIAGNOSIS. 653 in occlusion being represented in each section, with the line of diagnosis intersecting the occlusion of the mesio-buccal cusps of the first permanent molars of each class, and illustrating at a glance, the deviation from the normal mesio-distal relations of each lateral half in each class, division and subdivision. The use of the upper first molar for the purpose of noting mesio- distal variation of the lower dental arch presupposes a certain un- varying stability or a fixed position of this tooth in relation to the maxilla and the adjacent anatomical regions, which might be under- stood as being absolute, but such is not the case. Cases have been reported in which the upper first molar was mesial or distal to its normal position in the arch, although the infrequence of these cases and their observance only affects the classification as far as certain details of the treatment is concerned, the main points of the treatment indicated thereby being essentially unaffected. In simple, the indications for treatment as observed in the chart are, first, the restoration of normal shape and size of the dental arches in each class, second, the restoration of the normal mesio-distal relations of the arches in Classes II, III, and IV. Infra-occlusion. — Infra-occlusion, or lack of occlusion of the teeth, is a condition of abnormal development occurring in several different forms, and more or less common to all classes of malocclusion requiring special description in a classification based upon the mesio- distal variations only of malocclusion. Varying as it does from the slight infra-occlusion of one or two teeth to complex cases in which the entire dental apparatus is involved, its diagnosis, in any extensive form, places the presenting case in the class of the most difficult to treat. Associated as it usually is, with mouth-breathing, the functions of normal breathing must be restored before treatment is successful, as it is believed that mouth-breathing is the greatest causative factor in its production. Add to this the overdevelopment of one region and the under- development of another part in the same maxillary arch, and the extent of the abnormal conditions present may be understood. Variations of Infra-occlusion. — Infra-occlusion occurs in several forms, best described by the designation of the region in which it is observed, as infra-occlusion of incisors, cuspids and bicuspids, infra- occlusion of bicuspids and molars, and full bimaxillary infra-occlusion. Infra-occlusion of Incisors, Cuspids, and Bicuspids. — By far the most common form of infra-occlusion is observed in the 654 ORTHODONTIA. CLASS I CLASS II DIV. 1 CLASS II DIV. 1. SUB-DIV. CLASS II DIV. 2. \ LINE OF DIAGNOSIS. / Fig. 499. — Diagnostic chart of the mesio distal variations in malocclusion, Based upon the Angle classification. DIAGNOSIS. 65s CLASS II DIV. 2. aUB-DlV. CLASS IV \ LINE OF DIAGNOSIS. /^ Fig. 4v9. — Diagnostic chan of the mesio-distal variations in malocclusion. 1 ased upon the Angle classification. 656 ORTHODONTIA. lack of occlusion of the incisors, cuspids, and bicuspids, sometimes including the first and second permanent molars, varying usually with the extent of the mouth-breathing. It is especially characterized by lack of development of the pre- maxillary portion of the arches, and oftentimes overdevelopment of the posterior portion of the same arches. Fig. 498 illustrates an extensive case of infra-occlusion extending distally as far as the molar region. Bilateral Infra-occlusion of Bicuspids and Molars. — Exten- sive infra-occlusions involving the molars and bicuspids on one or both sides, may occur in any of the various classes of malocclusion. Fig. 652 represents a case of bilateral infra-occlusion of the molars and bicuspids, and in its mesio-distal relations, it may be classified as a Class I case. Fig. 500. Unilateral infra-occlusion 0} molars and bicuspids is a condition more commonly observed as the result of arch mutilation through extraction, especially of the first permanent molars. Full Bimaxillary Infra-occlusion. — Another extensive case of infra-occlusion, involving all of the teeth of both arches, described by Case,* is worthy of especial notice, as requiring special classification. As seen in the cast on the right of the cut, Fig. 501, the teeth, anteriorly and posteriorly, are very much too short in relation to the plane of occlusion, although being comparatively normally related mesio-distally, and the arches quite fully developed and of normal shape. When the jaws are closed, as in the model on the left of this * Dental Cosmos, for December, 1905, page 141 1. DIAGNOSIS. 657 figure, the facial appearance is that of an edentulous mouth, with its lines of senility caused by the approximation of the nose and chin, and the unnatural fullness of the lips and cheeks, as illustrated in the face mask on the left of the cut. The model and face mask on the right, the normal pose of the profile, was obtained by placing a piece of modeling compound between the teeth, and the distance between the arches of teeth adjusted until the profile appeared normal. Arch Predetermination. — An accurate conception of the normal size and shape of the dental arches in malocclusion is no longer a matter of guesswork since the mechanically and anatomically recon- structed arch has been made a possibility by the application of the laws of Bonwill in the synthetic reproduction of the normal arch for Fig. 501. any given case, as worked out geometrically by Hawley, who by a reversal of the method of triangle construction of Bonwill has succeeded in predetermining the size of the arch by constructing a triangle from a primary measurement of the arc of the centrals, laterals and cuspids. A scientific determination of the normal arch in any case of mal- occlusion not only removes any doubt as to the extent of arch expan- sion in treatment, but provides for the establishment of the normal function of articulation, which is most important in mastication, and preservation of arch integrity, which the construction from an equi- lateral triangle, aided by the relationship of length of cusps to depth 42 658 ORTHODONTIA. of overbite, and the compensating curves from cuspid to molars, affords by the harmonious working of these laws. Quoting from Hawley's article on arch determination, the con- struction of the triangles and reproduction of the normal arch for any given case is as follows: Bonwill's Diagram. — "In Fig. 502 we have Bonwill's geometrical figure, an equilateral triangle, AFG, inscribed within a circle, its base FG representing the distance between the condyles, which varies in the livmg subject from three to five inches. According to his plan, in >l- -B E -I4 D r - ■ ■ - ->** A ^ '^^Z 7 * , - '„>'^ / 1 * ^^^T ""*-. ^ A' X ' ' \ ^\. ^^^ ^' \ / / ' ^ ^\. /' ^^ / be, leav- ing the other pins untouched so that the other anterior teeth may be used as anchorage in the lateral movement of the first tooth. After the first tooth has been moved far enough mesially or distally, the next adjoining tooth is moved toward it in the same manner, and so on until all of the anterior teeth have been consecutively and bodily moved. OPERATIVE TECHNIC. 733 Treatment of Infra-Occlusion of Incisors with Sectional Arch. — By giving a slight bend occlusally in the middle section of the arch wire distal to the cuspids, the pms being locked in the tubes on all the teeth in infra-occlusion, force is exerted in the line of the long axes of the incisors, and the simpler cases of infra-occlusion may be cor- rected in this manner. The more pronounced cases may be treated the additional use of intermaxillary force or with the plain arch. Adjustment of Sectional Arch for Deciduous Dentures. — In the expansion of the deciduous dental arch, the sectional arch is adjusted after a method illustrated and described by J. L. Young. The cuspid teeth are banded and provided with two parallel and vertical tubes in which are fitted correspondingly located pins on the arch wire, Fig. 617. Fig. 618. {Butler.) Thesedouble locking pins and tubes lessen the liability of breaking the pins under the spring pressure from the straightening out of the loops which are arranged as shown in the drawing, one mesial and one distal to each cuspid. Auxiliary Lock Pins. — ^A stronger form of pin, to be used where there is a very great strain has been devised by Butler. It is in the form of a latchpin as shown in Fig. 618. This form of pin may be used on the molar anchor band when intermaxillary anchorage is to be used, or on the cuspids in expansion of the deciduous arch, or on any other ofhhe teeth where unusual strain is to be exerted. These pins are made with pliers, by winding .22-inch gold and platinum wire around the beaks of a pair of pliers with the ends fashioned as in Fig. 618, in steps, which are of different lengths for different lengths of tubes. 734 ORTHODONTIA. PART VII. TREATMENT. General Considerations. — ^The conditions involved in individual malocclusions must of necessity be considered in the same general way as are diseases or deformities of other parts of the body. There should be recorded on a chart the history of the case in some- what similar manner to that in vogue in general medicine. The form of chart in use by the author allows of a record of the age, health, and habits of the patient, the possible etiological factors involved, such as the effects of childhood diseases, measles, whooping-cough, diphtheria , symp- toms of rachitis, the conditions of the naso-pharynx, noting the presence of adenoids, enlarged tonsils, deflected septi, or enlarged turbinates. Also the association of visual or aural defects should be noted, with the possibility of their having the same general cause as the malocclusion. A study of the various facts brought out in a chart diagnosis of this kind cannot fail to be of great value in prognosis and treatment. In some cases, the history of the patient is of such a nature that treatment of the malocclusion alone is of little value, in others, it is the one necessary thing that will restore the normal function of the masticatory organs, and bring beauty to a face marred by lines of inharmony. Again, the treatment of the malocclusion may so stimulate the develop ment of structures and sinuses adjacent to the dental arches that better respiration is established, and better nutrition inaugurated through the established function of mastication. The possibilities of benefit to the general health through these and more obscure channels, such as a possi- ble stimulus to the organs of internal secretion by which bodily growth is controlled, are worthy of considerations. The lack of development in the dental arches can no longer be considered in the light of local etiology, when such profound symptoms of general disturbance of function, of nutrition, metabolism and bodily growth are found associated with many of the cases presenting with malocclusion. Some of the cases presenting with marked symptoms of pathological conditions in the nose and throat are apt to have suffered to such an extent the ill effects of the troubles coincident with the "vicious cycle" in which adenoids, mouth-breathing and malocclusion are in evidence, that restoration of normal conditions of either nose, throat or dental arches seems an impossibility. In other cases, however, if the patho- logical symptoms have been of short duration, and the orthodontic treatment instituted during a period of general bodily growth, the TREATMENT. 735 benefits of dental arch expansion and stimulation to the growth of the structures of the maxilla and adjacent regions of the internal naries have been very marked. The effects of habits in malocclusion are so important in their relation to treatment, that unless they are taken cognizance of, failure is apt to ensue. For example, if a malocclusion be caused by thumb- sucking, and the cause of the malocclusion be not prevented during treatment the continuance of such a habit will cause the return of the malocclusion. Local Considerations. — In making a diagnosis of the maloc- clusion, after noting the class, any peculiar features of malocclusion should be taken cognizance of, such as the prolonged retention of deciduous teeth, loss of permanent teeth, absence of germ of perma- nent teeth, impacted teeth, and supernumeraries. The X-ray should be brought into frequent use in determining the shape and position of the roots of impacted teeth, and supernumeraries. The relation of arch width to arch length, the height of the plate, and underdevelopment or overdevelopment of bony structures should be taken cognizance of. The depth of the overbite, and conditions involving supra- or infra-occlusion should be carefully noted with a view to their effect upon the articular movements of the mandible, and the possibility of restoration of natural articular as well as occlusal function. Finally, a study of the case should be made with reference to the problems of dynamics and anchorage involved, and treatment should not be instituted until they are satisfactorily solved. The beneficient results of treatment should follow along the lines of development of the dental arches, improvement in occlusion and facial lines, better masticating powers, better respiration, and better general health. Early Treatment of Arrested Developmental Conditions in the Arches. — Any arrested or deficient development of the arches of teeth may be diagnosed in advance of the permanent dentition, and should be stimulated to normal growth and development as early as the age of the patient will allow of the wearing of delicate appliances for the purpose. The lack of mesial and distal spacing between the deciduous incisors and cuspids at about five or six years of age is a very certain indication of a lack of anterior development sufficient for the proper eruption of the permanent teeth succeeding them. The upper deciduous arch may be in lingual occlusion, or the 736 ORTHODONTIA. lower arch may be mesial or distal to its normal position, or there may even be infra- or supra-occlusion present in the deciduous teeth, all of these conditions being readily diagnosed. If the deciduous arch needs widening, it is better to perform this operation some little time before the roots of the deciduous molars have begun to absorb, since the crowns of the permanent bicuspids are enclosed within the roots of the deciduous molars, as may be ob- served in Fig. 619, and the result of the expansion will be to move the crowns of these permanent teeth as well as the deciduous teeth and surrounding alveolar tissues into a larger arc, aflording a gentle stimulus to the normal development of the entire arch. Fig. 619 If treatment is delayed until just before the time for shedding of the deciduous first molars, the roots of these teeth, being almost absorbed, can afford no resistance to the appliance in expansion, and their crowns will be shed before any expansion can be accomplished in this region, which will then delay the development of the arch in this region until the permanent bicuspids are fully erupted, there being no other means of anchorage in the meantime, except what may be pos- sibly obtained through the ligation of the deciduous cuspid, which many times is prematurely shed. The author has obtained the best results in arch development between the ages of six and eight years, and in some cases still younger, especially in cases of mesial or distal occlusion, lingual occlusion of the TREATMENT. 737 whole, or portions of the, upper dental arch, and upper protrusions of Class I. It is reasonable to suppose, from the rapidity of development of the alveolar process during the primary stages of eruption of the permanent teeth, that the movement of the deciduous teeth some little time previous to the period when absorption of the roots of deciduous cuspids and molars is about to be initiated, conforms most nearly to a natural and physiological process, and that the amount of absorption of alveolar process in advance of moving teeth is comparatively slight, the change in these structures being analogous to the natural develop- mental changes which would occur in case no arrest of development had been observed. Fig, 620. Realizing the benefits of such early development of the dental arches, the orthodontic specialist prefers to operate upon the chil- dren in whose mouths the presence of firmly implanted deciduous teeth offer a firm resistance for the development of the dental arch in advance of the eruption of the majority of the permanent teeth. Fig. 620 illustrates the development of an upper dental arch in a case in which the deciduous molars were used for resistance throughout the treatment and the restoration of the proper size and shape of the arches at this age conforms more nearly to a physiological process or a stimulation to normal development, rather than a tearing down and rebuilding process to which such treatment is analogous at a mature age. Early treatment in a case of this kind is undertaken at a time when the alveolar processes are more cartilaginous in character than later, the teeth being thus more readily moved because of lessened resistance than when the cartilaginous structures are fully calcified. Again the function of the dental arches being restored early in child 47 738 ORTHODONTIA. life, all developmental processes in relation thereto, such as the growth of the dental and maxillary arches and the nasal cavities, and the con- formation of the muscles of mastication and expression, will have the best chance for normal development, and the attainment of har- mony in the profile will thus become a possibility through such normal relationships. Furthermore, the earlier treatment is undertaken, the less tendency exists for the return of the malocclusion, and the less the need of reten- tion, as age only increases resistance to tooth movement, confirms the deformity in its relationship by long and improper function of occlusion and muscular expression, and initiates structural changes in bony and muscular tissues which cannot be altered by treatment. PART VIII. TREATMENT OF CLASS I. Diagnosis. — Malocclusions of Class I (Angle), are recognized by the normal mesio-distal relationship of the dental arches, usually deter- mined by noting the occlusal relations of the mesio-buccal cusps of the Fig. 621. upper first permanent molars with the lower first permanent molars, when present in the arches. In the absence of one or more of these teeth, the occlusion of the bicuspids will serve to denote the normal mesio-distal relation of the dental arches. When a tooth is impacted, the closing up of the space for its eruption must be taken into account, and the occlusion of all of the erupted teeth must be observed as the TREATMENT. 739 cusp relation might in cases of this kind indicate a mesial or distal occlusion either of a molar or bicuspid, and confuse the diagnostician. The contraction of an upper dental arch will often cause the cusps of the lower first permanent molars to assume a slight distal position, which become normal in their relation on a very little expansion of the upper dental arch. This fact should also be taken into account, so that a case exhibiting these peculiarities of deficient development be not diag- nosed as belonging to Class II. Again, if the facial inharmony be taken as a guide without observ- ing the mesio-distal relationship of the dental arches, a case might be thought to belong to Class II, because it exhibited protruding upper incisors and an apparently receding chin, when an examination of the occlusal relations in the molar region would immediately prove it to be one of the not infrequent cases of Class I having only the facial symp- toms of Class II. Likewise cases belonging to this class simulate the general appear- ance in malocclusion and in the facial inharmony the characteristics of Class III with retruded upper incisors and an apparent protrusion of the lower dental arch and of the chin, while the molar teeth on each lateral half are in the normal mesio-distal relation of Class I. Another complication of Class I is the variation of the underbite from the normal line of occlusion to the "open bite" or infra-occlusal positions, or to that in which the underbite is very deep, the lower inci- sors often pressing into the gum tissue lingual to the upper incisors. The infra-occlusion may be in the incisor region or extend distally as far as the second molar, or there may be infra-occlusion in the bicus- pid region alone, or in the bicuspid and molar region and not in the incisor region. The variations in occlusal and facial inharmony are more varied in Class I than in any other class, and these factors, together with the mul- tiplicity of malpositions of the teeth, and the simulations in general appearance of the malocclusion of Class II and Class III, make the class under consideration the most misleading in its characteristics and difficult in its diagnosis. Relative to the multiplicity of malpositions of individual teeth, in Class I, one or more teeth may be in buccal or lingual occlusion, or in supra or «w/ra-occlusion, or in /or^o-occlusion, characteristics belonging, however, to any of the classes of malocclusion. Among the local etiological characteristics noted in this class, as well as in some of the other classes, are the prolonged retention of deciduous teeth, the premature loss of deciduous teeth, loss of permanent teeth, the 740 ORTHODONTIA. Fig. 622. Fig. 623. TREATMENT OF CLASS I. 74 1 shortening of mesio-distal diameters of permanent teeth through the ravages of caries, supernumerary teeth, abnormal frenum labium, and the habits of lip or cheek biting, thumb or tongue sucking and mouth- breathing. Fig. 624. Symptoms of mouth-breathing should be immediately noted, and the case referred to a competent rhinologist for examinationrof the^nose and throat and removal of nasal or pharyngeal obstructions if present. Fig. 625. Other habits such as sucking the thumb or tongue, and biting the cheeks and lips, should be combated from the beginning of treatment, or their continuance will disarrange whatever perfection of occlusal rela- tions that might be attained as a result of treatment. 742 ORTHODONTIA. Extraction, as a beneficial procedure, should be excluded except in rare cases, and usually where it has already been resorted to, the restoration of space which has been lost by contraction in the region of extraction, should be accomplished and the space retained by proper methods. The diagnosis of this Class being indicated by the normal mesio- distal relation of the dental arches, the treatment indicated should be along the lines of dental arch development according to the indica- tions for that treatment previously described. To follow a consistent sequence in describing the treatment of cases belonging to Class I, those cases, which, on account of their youth, and the greater possibilities therefore of the fullest development of dental arches, will be first described, and next thereafter in order the cases of more mature years in which the lesser development of dental arches is possible. Treatment of Special Cases. Case I. — ^Although the malocclu- sions of Class I present varied occlusions of the anterior teeth from supra- to infra-occlusion, there is a common type of malocclusion in which the overbite is normal, and the anterior malocclusion simply one of lack of development exhibited by lack of sufficient space for erupting incisors. A case of this character, age nine years, is shown in the occluded casts in Fig. 621. As is usual in such cases both the upper and the lower dental arches are deficient in their growth, and the indicated treatment is a gentle mechanical stimulation to normal development by means of the application of either the plain or sectional expansion arches. An examination of the upper dental arch, Fig. 622 shows that the deciduous cuspids and molars are still intact and firm in their positions, and capable of offering sufficient resistance to the appliance for lateral expansion and of carrying laterally with them the crowns of the per- manent bicuspids enclosed by the roots of these deciduous teeth. • Although the permanent central incisors and first molars have erupted, as far as development is concerned, it is still a partially decidu- ous dental arch, and the diagram for a .39 central incisor indicates that considerable anterior and some posterior expansion is necessary in order to secure sufficient development of the arch for the accommodation of the permanent teeth yet to erupt. The result of treatment of this upper arch, according to these indica- tions, is shown in Fig. 623 in which the after-treatment arch conforms to the .39 diagram which predetermined to a nice degree the extent of development necessary. Fig. 624 exhibits the appliances used for treatment of the upper TREATMENT OF CLASS I. 743 dental arch. Plain bands with lingual wire extensions and round buccal tubes were used for the anchorage, and a 17-gauge expansion arch for the force appliance. Lateral expansion was secured by ligating the lingual wire extensions to the expansion arch after placing it in position with a medium amount of lateral spring. Spurs were Fig. 626. placed on the arch to direct the deciduous cuspids distally and regain space for the unerupted laterals. A similar arrangement of the expansion arch and lingual wire extensions was used for the development of the lower dental arch. Fig. 627, The retention of the upper arch of this case is illustrated in Fig. 727, the deciduous teeth being utilized for resistance until such time as the absorption of their roots will render them unfit for such use. The width of the arch is retained by the lingual retaining wire, soldered to the bands upon the deciduous cuspids and molars, and the central incisors are held 744 ORTHODONTIA. firmly in approximation. by bands soldered together and cemented in position. The treatment of the lower arch was very similar to that of the upper, and the increased development obtained was retained by a lingual wire soldered to molar bands. The after-treatment model of this case, Fig. 625, represents the ex- FlG. 628. treme of dental arch development in a case in which the facial lines showed no particular indications of undeveloped dental arches. Case II. — Fig. 626 represents the right side in occlusion, before and after treatment, of an average case of Class I, the arches being con- tracted and the teeth anterior to the first molars in various positions of Fig. 629. malocclusion previous to treatment. After treatment the teeth are in normal occlusal relations as noted in the model on the right of this 'figure. The left side in occlusion, in Fig. 627, illustrates the corrected posi- tion of the upper left central from lingual to normal occlusion, and the regaining of the proper space for, and eruption to normal position of, TREATMENT OF CLASS I. 745 the left lower second bicuspid. Fig. 628 exhibits the restoration of the normal size and shape of the upper arch, the malposed teeth being placed in the line of occlusion, as noted in the cast on the right of the cut. Fig. 629 presents the chief difficulties encountered in the case, in the extent of the contraction of the anterior portion of the lower arch, and the attainment of the ideal in the size and shape of the arch as a final result. The lower unerupted bicuspid very quickly took advantage of its release from imprisonment between the first bi- cuspid and first molar, and erupted into occlusion without mechanical aid, lending its additional support as a keystone to hold the arch intact. The presence of the unerupted bicuspid in the process could be diag- nosed by the protuberance of the gum tissue overlying the tooth, without the use of the X-ray diagnosis often necessary in these cases. The appliances used in this case were the expansion arch and anchor clamp bands. In the upper arch, the left central was banded, and a ligature extended from a lingual spur to the arch, with a rubber wedge between the mesial angle of the tooth and the arch to assist in its rotation. Very little expansion was needed in the upper arch beyond that necessary for the accommodation of the left central, and the harmonizing in size of the upper with the lower arch. In the lower arch considerable lateral expansion was necessary, and the appliances were adjusted so as to obtain reciprocal anchorage from one side of the arch to the other through ligatures on the expansion arch. The left lower first bicuspid was banded, and a ligature extended from a mesio-lingual lug on the band to a spur on the arch wire, so as to secure the two necessary movements of rotation and lateral re-alignment of this tooth. The case just illustrated, although presenting some difficulties in the treatment of the lower arch, is simple compared with the problems of normal arch and occlusal restoration exhibited in the treatment of the next case, the right occlusion, before and after treatment of w^hich is shown in Fig. 630. Case III. — The case is that of a boy fourteen years of age, and in the model on the left of Fig. 630 may be noted the contracted arch, and the closing up of the space for the upper second bicuspid and the partial closure of the space for the lower bicuspids, which are impacted in the alveolus just external to their positions in the arch. The etiological factors in this case were obscure, in that the boy was a normal breather, of good history, and, beyond the pre- mature loss of the deciduous cuspids and molars as a mechanical 746 ORTHODONTIA. factor in the causation of the undeveloped arches, very little could be learned of a pathological nature which might have affected the nor- mal development of the dental arches. Fig. 630 Fig. 631. The occlusal view of the upper casts, before and after treatment, in Fig. 631, exhibits a degree of expansion which would not have been believed possible by the uninitiated in the secrets of occlusal restoration. The upper second bicuspid on the right side was freed from impaction, TREATMENT OF CLASS I. 747 and erupted to its proper position of occlusion, the cuspids also being restored to alignment, or rather the rest of the teeth in the anterior part of the arch changed to the cuspid alignment, as the cuspids were Fig. 632. Fig. 633. more nearly in their normal positions than any of the other anterior teeth. The lower cast on the left of Fig. 632 exhibits the impaction of 748 ORTHODONTIA. three teeth, two bicuspids on the right side and the second bicuspid on the left side, the release of which could never have been possible without the interference of the orthodontist. In the cast on the right, the successful accomplishment of the necessary expansion for the accommodation of these teeth in the arch may be noted. By com- parison of the before and after casts of both upper and lower arches in this case, the unusual amount of lateral expansion may be observed, showing how far short Nature came in her development of the arches, and indicating the possibilities of applied science in the restoration of the normal in development and the ideal in occlu- sion and harmony of contour of the arches of teeth. The picture of the left occlusion of the case before and after treatment, in Fig. 633, needs no description. The result of ideally correct treatment without extraction is very evident, and the classic lines in the after-treatment model can scarcely be excelled in beauty by any masterpiece of the sculptor's art. Notice the graceful curves of the arches, the symmetry and proportion of contour, the wonderful harmony which prevails in the arches through the perfect adjustment of each occlusal inclined plane of the antagonizing teeth to the requirements of normal occlusion. The accompanying profile of this patient in Fig. 634 is shown to illustrate the fact that such an extensive operation of expansion of the dental arches does not produce undue protrusion of the upper and lower lips. The lower part of the face is entirely in harmony with the rest of the features, being proportionate for its type, and in its contour hardly suggestive that an operation of this extent had been performed upon the dental arches. The appliances used in this case were similar to those in the previous case, and the treatment differed only in the extent of expan- sion carried out, and the opening of the greater number of spaces necessary for the accommodation of the teeth which were either par tially or wholly unerupted. Soldered spurs upon the arches guided the direction of the ligatures upon teeth contiguous to the spaces to be opened, some of which Fig 634. TREATMENT OF CLASS I. 749 teeth it was necessary to band, and provide with lingual spurs for the most positive action of the appliance to be exerted upon them. In the upper arch, the lateral incisors and right first bicuspid were banded and ligated to the expansion arch from spurs attached to their disto-lingual angles. In the lower arch, the teeth needing banding in a similar manner were the right cuspid and the left first bicuspid, as a most positive attachment of ligatures was necessary in order to reopen the adjacent spaces for the unerupted teeth. Case IV. — ^A very interesting case of Class I in the peculiarity of its malocclusion, and in the combination of appliances and anchorage nec- FiG. 635. essary for its treatment, is illustrated from the occlusal aspect of the upper arch before treatment in Fig. 635, the feature of particular interest being the disto-lingual position of the upper right cuspid, which, on account of its extreme distal position opposite the lingual embrasure between the two bicuspids, is apparently secure in its malocclusion, presenting unusual obstacles to its restoration to the line of occlusion. By a careful conservation of anchorage and operation of the appliances, the accomplishment of the desired result was secured, as shown in the after-treatment cast of the upper arch in Fig. 636. 750 ORTHODONTIA. Fig. 636. Fig. 637. TREATMENT OE CLASS I. 751 The primary anchorage and its usual re-enforcements by ligatures for expansion of the arch, is entirely inadequate to produce the desired results in a case of this kind, for although the space for the right cuspid could be regained by a proper direction of ligatures on the expansion arch, the control of the cuspid in lingual occlusion in this same manner is impracticable. Fig. 638. The cuspid needed first to be moved forward opposite its regained space by means of a traction screw operating from the first molar anchorage, being attached to the lingual screw, as seen in Fig. 637, the right angled end operating in a horizontal tube soldered to the mesial surface of a band upon the cuspid. 752 ORTHODONTIA. Fig. 639. Pig. 640. TREATMENT OF CLASS I. 753 The expansion arch was in operation at the same time enlarging the arch and making room for the cuspid, the incisors being directed toward the opposite side of the arch by spurs located toward the left side of the arch from each incisor, and the right lateral having a band with a lingual spur for more positive action of the ligature at this point. It is evident that the combined distally reacting forces of the ex- pansion arch on the buccal, and the traction screw on the lingual side of the first molar, would be greater than the resistance of the first molar without re-enforcement, and the use of intermaxillary anchorage for this purpose as illustrated in Fig. 638 effectually counterbalanced the tendency to distal movement of the molar, so that the forces acting mesially from this base could operate without disturbing the stability of the anchorage. Fig. 641. Fig. 642. The operation on the lower arch was comparatively simple, re- quiring lateral and anterior expansion to harmonize the occlusion with that of the upper arch, at the same time regaining the full space for the lower right first molar, part of the mesio-distal diameter of which had been lost through caries. The success of this combination of appliances may be noted in the right occlusion, before and after treatment, in Figs. 639 and 640, the cuspid occupying its normal position in the arch, and the occlusion of both arches being restored to harmonious cusp relationship. Case V. — Simulations of Class II. — An upper protrusion of Class I simulating Class II is illustrated in Figs. 641 and 642 before and after treatment. In addition to the protrusion of the upper incisors, the lower arch was contracted in the region of the second bicuspid which was une- 48 754 ORTHODONTIA. rupted, and its space in the arch considerably diminished on account of the early loss of the second deciduous molar. The use of the expansion arches for treatment of this case was very similar to its application in Class II with the intermaxillary elastics stretched from the distal end of the buccal tubes on the lower molar bands to the hooks on the upper expansion arch are illustrated in the drawing in Fig. 643. The resistance of the entire lower arch was enlisted by ligating all Fig. 644. Fig. 645. of the eight anterior teeth to the lower expansion arch, allowing the nuts to be tightened occasionally for enlarging the lower arch and regaining the space for the unerupted second bicuspid. By allowing the expansion arch to slide distally in the anchor tubes on the upper molar bands, all of the intermaxillary force was directed TREATMENT OF CLASS I. 755 against the labial surface of the incisors, and the normal occlusion of the anterior teeth restored. The patient had been a mouth-breather in early childhood, but had been operated upon for the removal of adenoids early enough so that ' through the restoration of the normal in occlusal relations of the arches of teeth, the asymmetry of the facial lines was completely overcome, as is evidenced from the photographs of the profile in Figs. 644 and 645. The asymmetry of the facial lines in this case is so similar to the most severe types of the first division of Class II, that a differential diagnosis cannot be made without a diagnosis of the cusp relationship of the arches of teeth in occlusion. Variations in the Overbite. — ^The occlusion of the upper with the lower incisors in Class I has a wide range of variance from the "end Fig. 646. to end bite" to the lapping of the upper over the lower incisors so as to completely hide the latter from view when the lips are parted and the teeth closed. Often the lower incisors are elongated and occluding with the gums lingual to the upper incisors. This condition is usually due to infra-occlusion of the bicuspids, or molars, sometimes to a supra-occlusion of the incisors at the same time. The plane of occlusion of the upper arch, instead of being convex is concave, and the treatment for this condition is the same in Classes I and II. One method for its treatment consists in the wearing of a bite plate for opening the bite in the incisor region, while the triangular use of the intermaxillary elastics as in Fig. 557 elevates the molars into occlusion. This method of treatment should be instituted, if possible, before the eruption of the bicuspids so that they may be made to seek the new plane of occlusion in eruption, and thus permanently retain the established occlusion. Another method of treatment of this condition of infra-occlusion. 756 ORTHODONTIA. which is applicable only after the eruption of the bicuspids, is to apply the light expansion arch as a double elastic lever springing it downward over hooks on upper bicuspid bands and under hooks on upper incisor 'bands, as in Fig. 608. A lingual arch attached in a similar manner can be used for retention. Case VI. — Simulations of Class III. — Fig. 646 illustrates a not uncommon case of Class I in which the characteristics of Class III are simulated in the apparent protrusion of the lower arch, and the inhar- mony of the facial lines. Fig. 647. Fig. 648. In the treatment of this case, anterior expansion of the upper arch alone was necessary, with bands upon the lateral incisors, and ligatures so directed and manipulated that the space for the unerupted cuspids was regained, after which a lingual retaining plate was used for reten- tion, a buccal spur extending through the cuspid spaces. In many of these cases which resemble Class III in the anterior mal- occlusion, however, it is necessary to apply intermaxillary force to sus- tain the upper molar anchorage. The lack of intermaxillary develop- ment in the upper arches of these cases is so marked that the use of the sectional arch for bodily movement of the incisors is advisable. TREATMENT OF CLASS I. 757 The profiles of this patient, before and after treatment, in Figs. 647 and 648, show the result of the treatment in restoring harmony to the face, and contrast the error of diagnosis from the facial lines alone, as a casual observance of the profile alone would indicate a protrusion of the lower arch characteristic of Class III. Fig. 649. (Lourie.) Case VII. — Infra-occlusion of Incisors and Cuspids. — ^Lack of occlusion of the incisors and cuspids and often of the bicuspids is a condition not uncommonly found, usually in mouth-breathers, and varying in extent somewhat according to the aggravation of the habit. It occurs in all classes of malocclusion, and because of the less number Fig. 650. of complications it presents in Class I, it responds more readily to treatment than in the other classes. As this condition is essentially a lack of development of the pre- maxillary portion of the arches, and an abnormal development, in many cases, of the posterior part of the arches, cases presenting infra-occlusion 758 ORTHODONTIA. of the anterior teeth should be treated as early as possible, and especially normal habits of breathing should be restored at the same time so that development may be further unimpeded by any nasal or other respira- tory obstruction. Fig. 649 illustrates a case of infra-occlusion of this class, the after- treatment model representing as near the ideal in treatment of these conditions as it is possible to attain. In the treatment of a case of this character, intermaxillary an- chorage should be established between the anterior parts of the upper and lower arches, and the expansion arches adjusted over spurred bands with the intermaxillary elastics extending from hooks on the lower expansion arch to hooks on the upper expansion arch, as shown in Fig. 650. It is advisable, of course, to first obtain the normal shape and size of each dental arch before applying the intermaxillary force. The elastics should be worn as continuously as possible and should be adjusted so as to operate very slowly in order not to move the teeth out of their sockets in advance of the developing downwards or upwards of the maxillary processes. It is possible to treat the simpler cases of infra-occlusion of the anterior teeth of Class I without the use of individual bands upon the teeth, the wire or silk ligatures around the incisors and cuspids and other teeth sufficing to move these teeth as desired. However, cases of any difficulty respond much more quickly when the individual teeth are banded, with spurs extending from the bands over the expansion arch. The same result may be obtained in the use of the sectional arch by bending the lateral loops to cause downward pressure on the vertical pins in the incisor tubes as suggested by J. L. Young. After the age of development has passed, the difficulties attendant upon retaining the teeth in occlusion, even though the operation might be otherwise possible and feasible, render it advisable in many cases to perform the simpler operation of extensive grinding of the molars and bicuspids until occlusion is obtained, even if the vitality of one or more of the molars be sacrificed in so doing. The author has obtained good results from this procedure in adult cases, observing, however, great care that a certain amount of cusp articulation is preserved in order that the functions of articulation and mastication may not be interfered with. In other words, the molars should not be ground off flat, but grooved for cusps as in grinding artificial teeth for articulation. The operation is a difficult one, in that it requires the greatest care not to grind too much upon certain teeth and not enough upon others. Occlusal contact points should be TREATMENT OF CLASS I. 759 ground a little at a time, on one side of the arch and then upon the other, approximating the arches of teeth only a limited amount at each of several sittings until occlusion is obtained. The shortness of the lips, especially the upper Hp, in most of these cases is such as to preclude the idea of elongation of the incisors to occlusion, an unnatural length being unesthetic. Infra-occlusion of Anterior Teeth Involving Change of Angle of Mandible. — In the severest cases of infra-occlusion of the anterior teeth, including the bicuspids and first molars the facial lines are very much disfigured, the angle of the mandible being apparently bent down- ward very obtusely, and the naso-mental distance greater than normal. This condition, described by Carabelli as "Mordex apertus," is more of a de- formity of the mandible than of the teeth ■ and their processes, but is found in the three main classes as noted by the mesio-distal relationship of the denta arches, and until a simpler classification of these mandibular deformities is found, it would seem reasonable to in- clude them in the " three-class scheme " of Angle's classification, where their in- dividual peculiarities may be described, and special treatment indicated. The causative factors, while very obscure, seem to be involved with mouth breathing, and abnormal work- ing of masticatory muscles, and with the diseases of childhood, especially rachitis (Lind). It would appear to the author that this condition is largely one of faulty respiration, which induces wrong muscular action upon the mandible, which becomes deformed as a result of the abnormal action of these muscles upon its surface, the form and structure of the bone being an expression of bone function. Some of these cases seem to have rachitic tendencies, others not. The treatment of advanced cases of this type is not attended with any degree of success, but if undertaken when the cases are incipient, in the early stages of childhood, good results may be obtained by the use of headgear and chin cap such as has been described by Law and Lind.* Fig. 651 illustrates the Lind headgear and chin cap. By the use of * Transactions European Orthodontia Society; 19 13. Fig. 651. 760 ORTHODONTIA. Fig 652 (Kern pie ). Fig. 653. TREATMENT OF CLASS I. 761 this apparatus at night only in very young children for a comparatively long period, the anterior teeth may be brought together and retained. The Lind apparatus depends upon the use of heavy elastics in front of the face from headgear to chin cap, while the Law apparatus has the heavy elastics adjusted from the side of the headgear exerting more (of an upward and backward pull. Case VIII. — Infra-occlusion of Molars and Bicuspids. — Figs. 652 and 653 illustrate a Class I case of infra-occlusion of the molars and bicuspids. This condition is a very unusual one, presenting as it does, Fig. 654, with the incisor region in perfect normal occlusal relations and an entire lack of occlusion from the cuspid to the second molar on each side. The patient was fifteen years of age and the function of mastication was limited to the six anterior teeth, in each arch. Such peculiarities of abnormal development are hard to explain, yet the fact that they exist ought to bring to bear a much closer study of the underlying factors in development which produced them. In the treatment of this case. Fig. 654, expansion arches were ad- justed to each arch, using the first molars as a primary anchorage for the clamp bands, banding the eight bicuspids, with spur extensions over the expansion arches above and below. The incisors and cuspids were allowed to remain free from ligation, as they were not to share in the movements to be undertaken. 62 ORTHODONTIA. Fig 655. Fig. 656. TREATMENT OF CLASS I. 763 Intermaxillary elastics were then adjusted between spurs on the buccal tubes of the molar clamp bands and from each expansion arch in the region of the first bicuspids. The after-treatment models of the case are shown in Figs. 655 and 656, showing the molars and bicuspids have been drawn into occlusion with each other, and a very successful result obtained. The retention consisted of a continuation of the use of the intermaxillary force in Fig. 657. connection with a more delicate and inconspicuous appliance for an indefinite period. Operation for Abnormal Frenum Labium. — The separation of the upper central incisors through the abnormal lingual attachment of the frenum labium, extending between the teeth to the lingual tuft in some cases, usually requires the bodily movement of the two teeth together, and their retention for a considerable period, until the frenum assumes a higher position in its growth. The present methods of treatment of these cases vary considerably; in one case the frenum is partially dissected from its attachment be- y64 ORTHODONTIA. tween the central incisors, by making incisions upon either side of it, and cutting it off with a pair of gum scissors sHghtly above the necks of the incisors, cauterizing the incised wound with the electric cautery ; in another case the operation may not be necessary after moving the usually diverging roots of the incisors together and retaining them during a sufficient period of growth. In either case, the centrals are fitted with bands having the vertical tubes of the new Angle appliance properly placed nearer the mesial angles of the incisors, and the bands cemented in position. If the cen- trals need rotating, the tubes may be located nearer the distal angles. A case of abnormal attachment of the frenum labium, before and after treatment by incision and moving the incisors together is shown in Fig. 657. Fig. 658. A portion of the new Angle sectional arch wire, .030 in., with ver- tical pins fitting the tubes on the incisor bands, and a contractile loop in the base wire between the centrals, as in Fig. 658, will serve to move them together, and act as a retainer as well. The movement of the incisors together occupies but a short period of time, but their retention is a matter of a year's time even in the young- est cases. The two central incisor bands are usually soldered together and cemented in position for the retention of these cases. It is not necessary to perform the operation of frenum resection in every case presenting with separation of the central incisors., the simpler and sometimes the more severe cases responding to the treat- ment indicated of movement of the incisors together, with a prolonga- tion, however, of the period of retention. TREATMENT OP CLASS II. 765 PART IX. TREATMENT OF CLASS II. Diagnosis of Class II. — The distinguishing characteristic of Class II in occlusal relations, is the bilateral or unilateral distal occlusion of the lower arch, the upper arch being narrow with protruding incisors in the first division, and retruded incisors in the second division. The facial profile is deficient in contour in such a way as to be indicative of the malocclusion, the chin and lower lip receding, and the upper lip protruding, in the first division of this class, as illustrated in Fig. 672. In the second division, a marked recession of both upper and lower lips and chin is noticeable, as in Fig. 688. The habit of mouth-breathing, and the open and drooping mouth, Fig. 659. the short upper lip, the receding chin and the facial expression, are peculiarly diagnostic of the first division of Class II, although it is sometimes difficult to distinguish it from the mouth-breather of Class I by observance of the facial inharmony alone. The presence of adenoids and enlarged tonsils is sufficient evi- dence of the causative factors underlying the mouth-breathing, which should receive early operative treatment by the rhinologist. The study of the possible etiology of the particular malocclusion manifested in Class II cases is important to the diagnostician, as upon his ability to recognize the chief causative factors present in these con- ditions rests his success or failure in their treatment. Following back the history of this class of cases to a period when cer- tain arrested developmental conditions were inaugurated, it may be assumed that, consecutively, arrest of development first occurred in one or both of the dental arches, and secondly, the later growth of the dental arches was along abnormal lines influenced by such factors as malocclu- 766 ORTHODONTIA. sion of the inclined cusp planes, and in many cases by the habit of mouth-breathing, with its abnormal tension of muscles. In a careful study of these conditions, the author believes that there is a predisposition to the malformation of the dental arches and the distal occlusion in these cases long before the eruption of the permanent teeth to occlusion. The existence of distal occlusion of the deciduous arches establishes the claim that certain persistent factors other than any cusp influence must have been pre-operative in causing these conditions in the decidu- FlG. 660. ous arches. That distal occlusion is not uncommon among children of less than six years of age is a fact which the model collections of the specialist in orthodontia can easily prove. Treatment of these conditions of distal occlusion in the deciduous arches is established upon the same basis of restoration of normal occlusion and development as with the dental arches which contain at least the four permanent molars of the second dentition. Figs. 659 and 660 illustrate the distal occlusion and facial profile of a child two years and ten months old. Not only is the distal occlusion of considerable extent, but the facial inharmony is easily noticeable at this age. TREATMENT OF CLASS II. 767 It is the author's opinion that the large majority of cases of distal occlusions are initiated during the retention of the deciduous teeth, and the impress of arrested function and growth so made upon the developing structures of the maxillae that none but artificial stimulus can again restore the normal in developmental conditions. It is possible that holding the mouth open in mouth-breathing gives the mandible its distal pose in these cases, and it is certain that in those cases of Class II, Div. i, having the [shortened upper lip, the abnormal tension of the muscles is an etiological factor in the narrowifig of the upper arch, which latter is, of itself, an effectual barrier to a forward pose of the mandible. In the treatment of certain cases of Class II, Div. i, it has been frequently observed that after a sufficient expansion of the upper dental arch, especially in children under ten years of age, the mandible moves forward of its own volition until the first molars are in correct mesio-distal relations. Recognizing the possibility of arrested or deficient development of the maxillary arches being primarily due to such general causes as malnutrition, or defective metabolism of a peculiar nature, associated with such local conditions as nasal stenosis and mouth-breathing, it will be admitted that the time the interference with development occurs will bear a certain definite relation to the period of deficiency in local asso- ciated functions of the oral and nasal cavities or of the general nutritive functions. Ottolengui very aptly states this theory in the following manner: "Malnutrition is the special cause of malocclusions of Classes II and III. The permanent teeth do not displace those of the primary set, but erupt into a larger, and what is more important, an entirely different arch, and the bony process is a new bone built about them during their eruption. Grant this hypothesis, and it is evident at once, that if, during this period of transformation, there be an interference with normal functions, there may and probably will be a lack of bone building nutriment. What will result? The permanent teeth, all larger than their predecessors, erupt into the same small arch which the temporary teeth had occupied, or into one insufficiently enlarged, because of insufficient nutritive elements." " Thus the consequent malocclusion oj the teeth will he in nature and degree constantly related to the extent and time of the disturbance in nutri- tional functioning.^'* * R. Ottolengui, "A Contribution to the Etiology and Treatment of Class II" Transac- tionb of the American Society of Orthodontists, IQ07. 768 ORTHODONTIA. If this lack of development be possibly due to functional insufficiency on the part of the organs of internal secretion, the time of the initial arrest of developmental conditions may extend back to prenatal or early postnatal life, and be related in extent to the degree of profound- ness or persistence of the initial functional disturbance. It is of special importance that the treatment of Class II cases should be begun at an early age in order to take advantage of a normal growth period during and after the correction of the malocclusion, the stimulation to normal development through treatment assisting materially in the per- manent retention of the normal occlusal relation. Cases may be begun before the eruption of the first permanent molars, but the author has had better results in beginning them just after the eruption of these teeth. Examination for Mouth -breathing and Tongue and Lip Habits. — ^Inasmuch as mouth-breathing is so commonly co-existent with distal occlusion, its diagnosis in any case should be followed by an examination of the nasal and pharyngeal passages by a competent rhinologist, and the removal of respiratory obstruction if found. Tongue and lip habits should be noted and their effects counteracted as soon as possible. Technic of Operative Treatment in Class II, Div. I. — The operative treatment of Class II, Div. I, may be divided into several stages, the restoration of normal size and shape of the dental arches, the shifting of the occlusal relations from distal to normal mesio-distal relations, and changes in the occlusal plane when necessary in cases of deep overbite, or of infra-occlusion of the anterior teeth. The restoration of the size and shape of the dental arches is secured by the application of the expansion arches as in Class I, and the shifting of the occlusion as obtained by the use of interrriaxillary force as illus- trated in Fig. 556. Normal Overbite. — ^In cases presenting with a short overbite of the lower incisors, the technic differs somewhat from that of cases in which the overbite is deep. In the cases presenting with a short overbite or a normal overlap of the upper incisors, the two consecutive steps in the treatment consist first, in the development or expansion of the den- tal arches, and second, in the shifting of the occlusion from distal to normal. The expansion arches are adjusted as in the treatment of Class I, except that the upper expansion arch is provided with hooks for the attachment of intermaxillary elastics. On account of the not infrequent breaking of the upper expansion arches through the pull of the elastics, the arch should be of a larger gauge as it enters the buccal tube di- minishing in diameter in the anterior arc, if it is desired. TREATMENT OF CLASS U. 769 Intermaxillary force and anchorage is secured by the attachment of the rubbers from the hooks on the upper expansion arch to the ends of the tubes on the lower expansion arch, as illustrated in Fig. 661. In simple cases of this class the first permanent molars may be used for attachment of anchor bands in case the second molars are erupted, since the intermaxillary force can be made strong enough to move the upper molars distally and the lower molars mesially. It may be necessary in the treatment of mixed dentures in which there is much anterior expansion needed in the lower dental arch, and in which the second premanent molars are unerupted, to apply intermax- illary force at first as a re-enforcement of the lower molar anchorage and later with force enough to shift the occlusion. YlG. 661. After the lower arch has been partially shifted the lower expansion arch'may be removed and a lingual arch soldered to the molar anchor bands which are provided with hooks instead of the buccal tubes. The lingual arch acts as a retainer and the lower incisors can be more easily kept clean during the long period of treatment. In more mature cases of this class, in which the bicuspids and second molars are present, and especially cases in which it is desired to move the upper molars distally to any extent, the anchor bands should be placed on the upper second molars and shifted to the first molars as soon as the desired movement of the second molars has been accom- plished. It may even be necessary to remove the anchor bands from the upper first molars and place anchor bands on the upper second, and even first bicuspids in succession for support of the expansion arch and further shifting of the occlusion in the bicuspid region. During the use of intermaxillary force for shifting the molar occlusion, the front of the 49 770 ORTHODONTIA. upper expansion arch should be kept free from the anterior teeth by tightening up the nut in front of the anchor tubes so as to apply the greatest amount of distally exerted force directly to the molar teeth. The strength of the intermaxillary force can be increased by using a heavier ligature or a number of the same size, cut from French tubing. While these manipulations of anchor bands and expansion arches are being carried on in the upper arch, the entire lower arch may be used part of the time as resistance for the shift- ing of the upper molar occlusion, by the ligation of a sufficient number of teeth to the lower arch to insure its stability. Again, the lower incisors may Pig 652. be ligated to the expansion arch and moved forward, and suc- cessively, also, the cuspids and the bicuspids, to secure direct appli- cation of the force from the turning up of the nuts in front of the lower anchor bands, these teeth, in turn, being moved mesially by the intermaxillary force. There is one very important detail in the manipulation of this anchorage in Class II and III cases which uught to be described in this connection, and that is the tipping backward of the upper molars in Class II, and the lower molars in Class III — and the tipping forward of the lower molars in Class II, and the upper molars in Class III — which in turn shifts the expansion arch upward or downward, as the case may be. To remedy this, and keep up the efficiency of the anchorage, the anchor bands should be removed and the angle of the incHnation of the tubes changed according to the necessities of the case and the class. Fig. 780 A exhibits the tipping of upper molars and downward inclina- tion of the expansion arch in a case of Class II, and B the restoration of the arch to position after re-aligning of the tube on molar clamp band. In shifting the occlusion from distal to normal in some cases in which the permanent teeth are nearly all erupted, it will be found that although the molars may respond readily to the intermaxillary force, the cuspids and bicuspids, especially in the upper arch, may not be so easily moved in the desired directions through the application of the elastics from the hooks upon the upper expansion arch to the distal TREATMENT OF CLASS II. 771 ends of tubes on lower molar clamp bands. In these cases, Casto has suggested the use of intermaxillary elastics between individual banded teeth of the upper and lower arch to overcome the difficulty, as in Fig, 661. Excessive Overbite. — A feature of no small importance in many cases of distal occlusion is the excessive overbite in the incisor region, which, if not overcome, will militate against the success of the treatment through the abnormal action of the inclined cusp planes of the incisors. • Often the lower incisors will be completely hidden from view by the upper incisors, in some cases striking the gums lingual to the upper incisors and causing absorption of the soft tissues. Again, it will be observed that the lower incisors occlude with the gingival ridges of the upper incisors, enhancing their protrusion, and initiating an inflammatory condition of the peridental membranes of the upper incisors. Fig. 663. The treatment of cases of Class II, Div, i presenting with the deep overbite varies from the treatment of cases of this class presenting with a short or normal overbite in that the plane of occlusion has to be altered until the overbite is normal. The lower molars must be ex- truded, and oftentimes, the upper or lower incisors intruded in their sockets. If these cases are begun before the eruption of the bicuspids and second molars, the wearing of a bite plate (Fig. 663) to hold the dental arches apart, and the wearing of the triangular intermaxillary elastics as in Fig. 557 to extrude the molars will change the occlusal plane so that while the occlusion of the molars is changed from distal to normal the normal overbite is obtained. The same method of treatment will apply to a lesser degree in more mature cases in which the bicuspids and second molars have erupted,. 772 ORTHODONTIA. but occasionally it is necessary to change the compensating curve of either or both of the upper and lower arches by the use of the expansion arches as double elastic levers as in Fig. 608. A modification of the bite-plate principle has been embodied in an inclined plane of 26 gauge clasp metal, Fig. 664, soldered to the lingual surface of gold bands, cemented upon the upper central incisors. This suggestion (Reoch) is adaptable in most of the fixed inclined planes in use at the present writing for changing the over- bite, and it is useful as well in the retention of Fig. 664. . these cases. Another form of the bite plane is seen in the looped wire plane (Young) attached to incisor bands as in Fig. 759. In order to establish the bite plane so that the upper incisors are not bound together, and so that each incisor may have freedom to exercise its function in occlusion,. Hawley has suggested the use of the individual staple planes as in Fig. 661. Treatment of Special Cases. Case I. — Fig. 668 repre- sents a case of bilateral distal occlusion of a seven-year-old boy whose facial profile Fig. 668 indicated that he was suf- fering from mouth-breathing. Considerable adenoid tissue was removed by a rhinologist, and after a few days' recu- peration from this slight operation, treatment of the maloc- clusion was inaugurated by first expanding the dental arches, opening up spaces in the upper arch for the permanent laterals, and in the lower arch for the cuspids. The Hawley chart for a .39 incisor indicated a great deal of lateral de- velopment of both arches which was obtained with expan- sion arches before the treatment for the distal occlusion. Intermaxillary elastics were then applied from hooks upon the upper expansion arch to the distal ends of the tubes upon the lower molar anchor bands, and the occlusion shifted from distal to normal. The final result in occlusion is seen in Fig. 667. The before and after treat- ment profiles of the patient are seen in Figs. 668 and 669. Such a series of operations as were performed upon this patient, first in the removal of the post-pharyngeal obstructions, second, the cure of the mouth-breathing habit, and third, the restoration of the normal function and growth of the dental and maxillary arches through scientific arch expansion and occlusal restoration cannot fail to be of the greatest benefit in cases of this character. Case II. — ^A very typical case of Class II, Div. i,is illustrated in Fig. 665. TREATMENT OF CLASS II. 773 Fig. 666. Fig. 667. Fig. 668, Fig. 669. 774 ORTHODONTIA. Figs. 670 and 671, the before- treatment models on the left exhibiting full distal occlusion of the lower arch, the protrusion of the central incisors in the upper arch, accompanied by all the displeasing and inhar- monious facial lines of the mouth-breather as seen in the short upper Fig. 670. lip, and the rolling of the lower lip under the upper incisors, illustrated in the front and profile pictures of the case before treatment in Fig. 666. The expansion arches were adjusted to both upper and lower dental arches in a manner similar to the adjustment in Fig. 550, ligating the Fig. 671. anterior teeth, and considerable lateral spring was given to the upper expansion arch to obtain the effect of widening the upper arch poste- riorly and retruding the upper incisors. TREATMENT OF CLASS II. 775 The treatment of the case was aggravated by the loss of the lower right first permanent molar, as it was necessary to regain this lost space by banding the second bicuspid and ligating it to the lower Fig. 672. expansion arch by a spur soldered a little in advance of this tooth, and turning up the nut on the expansion arch until normal occlusal re- lations were established, the intermaxillary force on this side being 776 ORTHODONTIA. made strong enough by doubling the elastics to resist too great a distal movement of the second molar. The models on the right of Figs. 670 and 671 illustrate the very per- fect occlusal relations which were established, and the pictures on the right of Fig. 072 exhibit the improvement in the profile as the result of treatment. The retention in this case consisted of interlocking spurs extending from upper to lower molar anchor bands, the upper arch being also retained in its altered shape by a lingual arch connected with the upper molar anchor bands, and attached to incisor and cuspid bands. Treatment of Class II, Div. 1, Infra-occlusion. — One of the most difficult complications occurring in any class of malocclusion is that of the "open bite," or lack of occlusion extending from the central incisors distally sometimes as far as the first and second molars, the arches being separated anteriorly from one-sixteenth to one-half an inch, according to the degree of malformation present. The inability to close the teeth anteriorly renders mouth-breathing more or less of a necessity, since lip function is almost 'entirely lacking in these cases, and the distortion of the features is much more dis- pleasing than if only the distal occlusion were present. The combination of "open bite" malocclusion and distal occlusion is such as to. increase the difficulties of treatment, and sometimes to baffle the efforts of the most expert operator. In the treatment of an "open bite" distal occlusion of the first divi- sion of Class II, the advisability of applying force for the restoration of the normal mesio-distal relationship simultaneously with, or pre- vious to, the application of force for the closing of the bite, will depend largely upon the age of the patient and the extent of the infra- occlusion of the anterior teeth. In a child under twelve years of age, the greater possibilities of development and growth of the alveolar process and underlying bony tissues of maxilla and mandible, might call for much more ideal treat- ment than in a more mature case. For example, the distal occl usion and "open bite ' ' malocclusion would respond readily to treatment, and if normal breathing and lip function were restored and an effectual retention of the restored occlusion be secured in the child under twelve years of age, success in the attain- ment of ideal results may be somewhat assured. In the adult the conditions for ideal treatment are very unfavor- able, since, although it might be possible to restore the normal rela- tions of occlusion and close the bite by the efficient use of intermax- TREATMENT OF CLASS II. 777 illary force, the indefinitely continued use of the same force, with a multiplicity of bands and wires for the retention of the normal rela- tionship, would render it somewhat inadvisable in the majority of cases. However, there is a method of treating such a case which appeals to the author as reasonable and practicable, both from his own ex- perience and from that of others, viz., to close the bite by grinding down the cusps of molars and bicuspids, allowing the front teeth to occlude. Case III.-^To illustrate, in Figs. 673 and 675, is represented an "open bite" bilateral distal occlusion of a fifteen year old boy, an Fig. 673. habitual mouth-breather, anemic in temperament, and with so few ^ of the teeth in contact that mastication of his food was an impossibility. To add to the difficulties of treatment, the upper right first and second molars were in lingual occlusion, and the crown of the lower left first molar was destroyed by caries. In order to be conservative of anchorage, the first step in the treat- ment was to bring the upper molars into buccal positions, and allow them to settle into occlusal relations with the lower molars before proceeding with the further treatment of the case. 778 ORTHODONTIA. The expansion arches and rubber elastics were then adjusted as in Fig. 556, for shifting the occlusion, which was successfully accomplished after a few months' treatment, but with the result that the anterior open bite was somewhat increased, as is usual in these cases. Although not assured of successful retention of the mesio-distal relationship of the arches and the occlusion of the anterior teeth, intermaxillary force was applied between the upper and lower incisors, cuspids, and bicuspids, as in Fig. 650, with the result that although these teeth moved more or less readily into occlusion, the appearance Fig. 674. was not as much improved as might be expected, the incisors elongating to an abnormal extent, and not carrying the process with them. The intermaxillary force was withdrawn, and the anterior teeth allowed to settle back into their former positions, and the method of treatment changed in a manner that has proved of more permanent value. The plan was adopted of so grinding the molar cusps of both upper and lower molars to close the bite that the inclined planes could be made to act as a permanent retention for the restored mesio-distal relationship TREATMENT OF CLASS II. 779 of the arches, and by very carefully grinding one cusp at a time, and exaggerating the distal inclines of the lower and the mesial inclines of the upper molar cusps, this desirable result was effected, retaining the normal mesio-distal relationship without the aid of any appliance such as the interlocking planes usually used for the purpose. The front view of the restored occlusion may be seen in Fig. 674, and the effectual interlocking of inclined planes of the cusps of the molars and bicuspids in Fig. 676 is of more than passing interest in view of the difficulties surrounding this class of cases in which distal occlusion, Fig 675. "open bite" malocclusion, and the confirmed habit of mouth-breathing were such insurmountable obstacles to any other method of treatment. One very gratifying feature of the treatment was that the boy had been examined by a rhinok)gist previous to coming under the author's care, and, although adenoids had been found, it was considered best to await the results of orthodontic treatment before they should be re- moved, and upon referring the case back to the nose and throat spe- cialist, he was unable to find any adenoids, which was a surprise, as such an occurrence had not before been recorded. 78o ORTHODONTIA. The disappearance of these adenoids was no doubt due to the ex- pansion of the upper arch, and restoration of normal occlusion, which gave better opportunities for normal breathing and better masticating function, so that the tonsillar growths were reabsorbed through a restoration of functions which meant increased metabolism and con- sequent improved nutrition. The author has also performed the operation of grinding the cusps of the molars and bicuspids in open bite malocclusions of the anterior teeth of adult cases of Class I and Class III with very gratifying success. Fig. 676. Care should be taken that the inclined planes be preserved in the grind ing, and be made to serve the purposes of articulation as well as occlu- tion by trying the articular movements of the mandible during the proc- ess, and seeing that the stress of articular mastication is properly sup- ported by both buccal and lingual cusps of molars and bicuspids, as is done m the grinding of artificial teeth upon an articulator constructed upon the Bonwill principle. In very severe cases of open bite malocclusion, it may be found necessary to devitalize the pulp of one or more of the molar teeth, since TREATMENT OF CLASS II. 78 1 the pulp cavity will have to be partially encroached upon in order to do sufficient grinding to secure occlusion of the anterior teeth, and yet this need not be considered an objection in view of the benefits obtained through the proper performance of masticatory function, and the correction of the mouth-breathing habit. Treatment of Class II, Div. 1, Subdiv.— The characteristics of the subdivision of Div. i, Class II, are very similar in the general appearance of the dental arches to those of the full first division, the upper incisors being protruded, the upper arch narrow, and the facial disfigurement almost identical, the distinguishing feature of the sub- FiG. 677. division being the unilateral distal occlusion, one lateral half exhibiting normal mesio-distal relations. The treatment, therefore, follows along the same lines as if the occlusion was distal bilaterally, except that it is obviously imnecessary to shift the occlusion on the normal side, although intermaxillary elastics of less strength may be applied on that side to assist in balancing the forces on each side of the mouth. Case IV. — ^Figs. 677 and 679 exhibit a case of Class II, Div. i, sub- division, in which the right lateral half is m distal occlusion, the left being in normal mesio-distal relations in the region of the first permanent 782 ORTHODONTIA. molars. The space for the eruption of the lower left second bicuspid being partially lost through premature loss of the deciduous second molar, the lower left first bicuspid and cuspid drifted into this space until they occupied distal positions. The expansion arches were applied in the same manner as de- scribed for the treatment of the full bilateral distal occlusion, the mesial force upon the lower left first molar being compensated by the distal force exerted by the expansion arch in forcing the lower left cuspid and first bicuspid mesially into their normal positions. This latter move- ment was expedited by ligating from a lingual spur upon a band on the Fig. 678. first bicuspid to a spur on the expansion arch slightly forward of the first bicuspid. After restoring the size and shape of the individual arches, and shifting the occlusion to normal relations, the result shown in Figs. 678 and 680, in right and left occlusion, was obtained. Intermaxillary retention was used in this case for a few months only, as the tendency of the dental arches was to remain in normal relations after normal occlusion and function of the occlusal planes had been restored. Treatment of Class II, Div. 2. — The occlusal characteristics of the second division of Class II include a distal occlusion of both lateral TREATMENT OF CLASS II. 783 Fig. 679. Fig. 680. 784 ORTHODONTIA. halves of the dental arches, with contraction of the anterior portion of the upper arch, usually presenting with some of the upper incisors in- clining lingually, or overlapping, as illustrated in the classification chart. As with the first division of this class, the profile shows the effect of the distal occlusion, though not to such a marked degree, the lower third of the face being more uniformly receded from the normal pose. Although cases of this division are usually normal breathers, it is not unusual to find mouth-breathers among them. Fig. 68 1. The distal occlusion in this division is probably in existence in the deciduous arches before the eruption of the first permanent molars, and the upper incisors are forced into lingual and overlapping positions through Nature's effort to conform the arches to some uniformity in size for better occlusion, the pressure of the lips being powerful factors in such arch conformation. Case V. — ^Fig. 68i illustrates the right occlusion of a case of bilateral distal occlusion in an eleven year old child, the upper central incisors inclining lingually and overlapped by the lateral incisors. In the treat- ment of this case, the intermaxillary elastics were applied for shifting the occlusion to normal mesio-distal relations, keeping the upper central TREATMENT OF CLASS II. 785 incisors clear of the lower incisors by expanding the upper arch and moving the deflected central incisors towards their normal positions a little in advance of the mesial movement of the lower dental arch. The restoration of normal relations of occlusion in Fig. 682 is of exceptional interest in that the mesio-distal relations of the arches were not artificially retained, the normal function of occlusal planes of the teeth being sufficient to hold the dental arches in their normal pose. The only retaining appliance worn consisted of a lingual retainer for the upper central incisors, being attached to bands upon the lateral incisors. Treatment of Class II, Div. 2, Subdivision. — The occlusal rela- tions of one lateral half of the dental arches being normal in the sub- FlG. 682. division of the second division of Class II, treatment for shifting the occlusion is necessary only upon the lateral half which exhibits distal occlusion. Expansion of both arches, however, may be necessary, in order to secure normal size and shape of the dental arches. Case VI. — A characteristic case of this subdivision is illustrated, before and after treatment, in Figs. 683 and 684, right occlusion, and 685 and 686, left occlusion. 5° 786 ORTHODONTIA. Fig. 683. Fig. 684. TREATMENT OF CLASS II. 787 Fig. 685. Fig. 686. 788 ORTHODONTIA. The distal occlusion is on the right lateral half, and the apparent simulation of a distal occlusion on the left side is due to the closing up of the space for the lower second bicuspid which is unerupted, allow- ing the first bicuspid to drift back until it is in contact with the first molar, carrying along with it by lack of anterior development, the cus- pid and incisors on the left side. An X-ray of the left side of the mandible revealed the presence of the second bicuspid in its proper place but, of course, unerupted. Upon the adjustment of the expansion arches, the upper with hooks Fig. 687. for the intermaxillary elastics, and the lower with a spur opposite the lower first bicuspid which was banded and ligated to the spur, the intermaxillary elastics were applied to both sides of the arches, that on the right being adjusted to shift the distal occlusion to normal, and the one on the left to re-enforce the lower molar anchorage which is to resist the force used to move the cuspid and bicuspid on that side forward in the line of the arch. Immediately upon the removal of the appliances, the case presented the appearance seen in Fig. 687, in which the anterior part of both arches seems to be abnormally protruded, a condition which it has been er- TREATMENT OF CLASS III. 789 roneously claimed the orthodontists of the " new school" are apt to ob- tain as a result of their treatment without extraction. From four to six weeks after this model was made, the teeth had settled back through the guidance of the retaining appliances to the beautiful relations of occlusion shown in Figs. 684 and 686. Fig. Fig. 6S9. The before and after treatment profiles of this case, Figs. 688 and 689, show a decided improvement in the art relations of the face. PART X. TREATMENT OF CLASS III. Diagnosis of Class III. — This class presents with bilateral or unilateral mesial occlusion of the lower dental arch, and, in the extreme, is probably the most disfiguring of any class of malocclusion. In cases of this class the maxilla is usually considerably arrested in develop- ment, and the mandible protruded, with its incisors inclining lingually. Most all of the cases of Class III are mouth-breathers, and naso- pharyngeal obstructions are unusually persistent. Accompanying many of these cases is the condition of "open bite" malocclusion with its added difficulties of treatment. The inception of mesial occlusion is during a very early period in child life, when it is least noticeable in the facial lines, and yet it is at 790 ORTHODONTIA. this early period when the malocclusion should be diagnosed and the abnormal conditions overcome which are causative of it, if the most beneficial results are to be obtained. In severe cases of this class, the angles formed by the rami and body of the mandible disappear, leaving almost a straight line from the chin to the ear. These cases may usually be diagnosed from the profile, the mandible being protruded, and the upper lip receding. The conditions of arrested development are usually persistent, the upper arch remaining small and undeveloped, and the lower arch changing in form according to the general direction of abnormal ten- sion of muscles. The etiological factors are somewhat obscure, although it is believed that the habit of holding the mandible forward to assist in breathing when the faucial tonsils are hypertrophied, has a strong tendency to cause the mesial occlusion. Fig. 6qo. Hypertrophied or diseased tonsils should beremoved'as early as diag- nosed, since if they are allowed to remain, it is impossible to overcome the faulty breathing, and abnormal relations of muscles which persist in holding the mandible forward. Technic of Operative Treatment in Class III. — The operative treatment of Class III may be divided into two stages, the restoration of the normal size and shape of the dental arches, and the shifting of the occlusion from mesial to normal relations. The use of the intermaxillary force for shifting the occlusion is necessary, as in Class II, although the direction of the force and the manipulation of the anchorage is exactly the reverse from that in the second class. TREATMENT OF CLASS III. 79 1 The direction and points of application of the intermaxillary force in treatment of Class III may be seen in Fig. 690, the elastics extend- ing from the distal ends of the tubes on upper molar clamp bands, to the hooks on the lower expansion arch. The expansion arches are illustrated without ligatures, so that the intermaxillary anchorage may be more clearly shown. In actual treatment, proper ligation of the teeth in both dental arches to the expan- sion arch should be made according to the tooth movements desired, and the degree of re-enforced anchorage necessary in either arch. It is also necessary, in extreme cases of this class, to shift the anchor bands from first molars to bicuspids in the lower arch, in order to con- serve anchorage and secure distal movement of the bicuspids. Fig. 691, Owing to the fact that mesial movement of the teeth requires less force than distal movement, appliances almost always operate to move the teeih of the upper arch mesially more than to move the teeth of the lower arch distally in these cases. It is considered especially advantageous in this class of cases to obtain, if possible, a deep overbite, or overlapping of the upper over the lower incisors after shifting of the occlusion, as the increased length of the inclined cusp planes serves to more efifectually retain the restored relations of occlusion than where but a short overlapping is present. It is advisable to begin the treatment of this class of malocclusion as early as it is possible to manage the child, for with added years comes an exaggeration of the deformity, the mandible assuming a more for- ward pose, and the shape of the bone and the relations of the muscles 792 ORTHODONTIA. becoming conformed to an abnormal condition which makes it much more difficult and sometimes impossible to completely overcome. Case I. — Fig. 691 exhibits the model of the case of the seven- year-old boy, from whose throat the adenoids and tonsils shown in Fig. 492 were removed at the beginning of treatment. Anchor bands were fitted to the deciduous second molars and the 18 gauge expansion arches adjusted as in Fig. 690, the intermaxillary elastics being attached in the same manner as in a dental arch of per- manent teeth. The occlusion was changed in a few weeks to that shown in Fig. 692 and a persistent retention by means of the buccal spurs was established, and the case dismissed to be seen only at intervals of a couple of months, Fig. 692. until the permanent teeth should erupt, in order that any untoward developments might receive immediate attention, should they arise. The profile pictures of this case are exhibited in Figs. 693 and 694. After a year's retention, the development of the facial lines through the establishment of normal functions of occlusion and respiration has been most gratifying. Case II. — Another case of this class, the before treatment models of which are shown in Fig, 695, and which was treated by M. T. Wat- son, is unusually interesting in view of the fact that the restoration of occlusion and facial lines was accomplished solely by means of the Angle chin cap and headgear, a combination which has fallen somewhat into disuse since the general adoption of intermaxillary force for the mesio-distal changes in occlusion. TREATMENT OF CLASS III. 793 Beginning with a very gentle elastic pressure for the first few days of treatment, two No. 33 Goodyear elastic bands were adjusted between headgear and chin on each side, followed in the course of a week Fig. 693. Fig. 694. by the substitution of a No. oooj for the lower of the two bands, which represented the maximurn of force used in the treatment. Aside from a slight crowding of the lower incisors, the results of about six weeks' treatment produced almost normal mesio-distal Fig. 695. relations of the dental arches, the final occlusal relations established being shown in Fig. 696. The necessity for the subsequent use of appli- ances inside of the mouth for perfecting the occlusal relations does not detract from the scientific value of the method just described for early treatment of this class of cases, especially as it is the only recorded case 794 ORTHODONTIA. in which the treatment was confined solely to the use of the chin re- tractor, and therefore exhibiting " a change which must necessarily be confined to the shape of the mandible itself, or to a change in the tem- poro-maxillary articulation, or both, the latter probably being the case." (Watson.) Fig 696. Fig. 697 illustrates the before and after treatment profiles of the case, the latter picture being taken about four months after the first one. The slight prominence of the lower lip in comparison with the upper may be accounted for by the loss of the upper deciduous central incisors during the treatment, and the lack of the permanent centrals being sufficiently erupted to lend any contour to the upper lip. Fig. 697. Case m. — ^A comparatively simple case of this class is illustrated in Fig. 698 before and after treatment. This case was undertaken just as the bicuspids were erupting to occlusion and the change from mesial to normal occlusion as a result of treatment gave the cuspids and bicus- TREATMENT OF CLASS DI. 795 pids an opportunity to complete their eruption into normal locking with the inclined planes of their antagonists. The expansion arches were placed upon both upper and lower arches and the intermaxillary elastics stretched from hooks soldered well forward upon the lower expansion arch to the distal end of the buccal tubes upon the upper molar clamp bands, as in Fig. 690. When the upper incisors are but slightly distal to the lower incisors as in this case, the first effort should be directed to moving the upper incisors into positions mesial to the lower incisors, so as to gain the advantage of the inclined planes of the lingual surfaces of the upper incisors acting upon the labial inclined planes of the lower incisors during the rest of the treatment, for until this change is made, the reverse action Fig. 698. of the inclined planes of the incisors will tend to prevent a change in occlusion of the molars. To accomplish this movement of the upper incisors, the lower ex- pansion arch was securely ligatured to the lower incisors and bicuspids, and the lower arch used as a stationary anchorage, as it were. The upper incisors were then ligated to the upper expansion arch, the nuts in front of the anchor tubes turned up tight twice a week and the inter- maxillary force being constantly in action, not only prevented the upper molars from distal movement, but hastened the mesial movement of the upper incisors. After this change in the occlusion of the incisors was effected, the intermaxillary force, continuing in action, produced the change from mesial to normal occlusion of the lower molars. It will be ob-served from the cut that some expansion of both arches was accomplished at the same time. 796 ORTHODONTIA. Even with such a slight change in occlusion as is exhibited in this case, a very decided improvement in the facial lines is seen in the com- parison of the before and after treatment profiles in Figs. 699 and 700. Case IV. — A much more difficult case than the one just described on account of increased age and consequent greater density of alveolar tissues and conformation of occlusion and facial lines to abnormal conditions is illustrated in Fig. 701, the before and after treatment models being observed from the left side. Fig. 699. Fig. 700. Orthodontists have been cautioned against the possibility of ab- normal eruption of the lovi^er third molars during or after the period of distal movement of the lower second and first molars in cases of this class, and while it is advisable to observe unusual precautions to pre- vent any maleruption of these teeth, the experience of the author in this case and other similar cases, leads him to believe that in the majority of cases the restoration of occlusion and consequent proper function of the maxillae, may aid rather than interfere with the normal develop- ment of the third molars. The lower third molars in this case erupted into their normal positions soon after treatment was finished, and with no more difficulty than if the operation had not been performed. The change in the profile is apparent from a comparison of the before and after treatment pictures in Fig. 702. Case V. — ^There are many cases occurring in practice which seem t« be exceptionally difficult to diagnose and treat on account of the loss of TREATMENT OF CLASS III. 797 many of the permanent teeth, and the consequent complications caused by the migration and elongation of remaining teeth in already contracted arches. Fig 701. Fig. 702. A case of this character, age twenty years, belonging to Class III, is exhibited in Figs. 703 and 704, before and after treatment of both right and left sides of the mouth. The loss of many of the teeth by caries 798 ORTHODONTIA. and necessary extraction, and the elongation of teeth which had no antagonists, rendered it exceedingly difficult to treat, especially as the problems of anchorage for the use of intermaxillary force seemed rather uncertain. Fig. 703. By a careful conservation of anchorage, however, the case was finally brought to a successful completion, the after treatment models being shown on the right of Figs. 703 and 704, with retaining appliances in position. Fig. 704. In this case the plate plays a very important part, not only in retain- ing temporarily the spaces regained for permanent teeth, but also supply- ing artificial substitutes for the missing natural teeth. A view of the upper casts of this case in Fig. 705 shows the retention of five of the anterior teeth with a lingual wire soldered to the left TREATMENT OF CLASS III. 799 cuspid and right lateral incisor bands, and a roof plate, with spring clasp attachments and three artificial teeth, effecting the retention of the rest of the teeth in the upper arch. Another plate with spring clasp attachments and artificial substi- FlG. 70: tutes for natural teeth, accomplishes the greater part of the retention of the lower arch as illustrated in Fig, 706. The profile of this case, before and after treatment, is exhibited in Fig. 707, the improvement in facial contour being very pleasing. Fig. 706 At a later period, the plates were removed and bridge- work inserted for permanent retention and increased function of mastication which was attained. Case VI. — A case like that illustrated in Fig. 708, pre- sents such difficulties in the way of treatment, that the operation of 8oc ORTHODONTIA. resection of the mandible for the purpose of securing the best results in improved mastication and facial contour has occasionally been recommended. The infrequency of the operation of mandible resection, and the reports of a few failures in the hands of incompetent surgeons, has not aided in making it more desirable. The operation has been successfully accomplished by the general surgeon, and it is be- lieved by the author that in the near future, it will be more commonly performed and by the trained oral surgeon, especially with the help of the orthodontist. In the particular case illustrated in Fig. 708, the author performed an orthopedic operation which resulted not only in improvement in Fig. 707. masticatory occlusion, but in a transformation of the disfigured facial lines into those of a most pleasing character, besides restoring the func- tion of correct phonation in speaking. The operation consisted in opening up an artificial space upon each lateral half of the maxilla, between the cuspid and first bicuspid, the width of a bicuspid tooth, moving the six anterior teeth forward to occlusion with the lower incisors, by a conservative use of intermaxillary force and special manipulation of the expansion arches. At the same time, the teeth in the lower arch were moved distally as far as distal inclination of the lower incisors, and the accompanying movements of the upper teeth would allow, until the result shown in Fig. 709 was attained. The upper arch was retained by a fixed lingual TREATMENT OF CLASS III. 8oi arch soldered to bands upon the cuspids and first bicuspids, with buc- cal hooks upon the bicuspid bands, and with elastics extending from these to hooks on lower cuspid bands for a continuation of the in- termaxillary force as retention. Artificial teeth, soldered to the lingual retaining wire, artistically filled up the opened spaces until such time as permanent bridge-work could be substituted for the retention. Fig. 708. The improvement in the profile may be seen upon comparison of the before and after treatment pictures in Figs. 710 and 711. Case VII. — ^Double Resection of the Mandible in Class III. — We are indebted to Max Ballin for the first published illustrations of a suc- cessfully operated case of double resection of the mandible, a brief description of which is given here in condensed form. The patient was a young man twenty-two years of age, who pre- sented himself to the surgeon on May 10, 1907, for possible surgical treatment of a protruded mandible, which orthodontic treatment had for some reason failed to remedy. The extent of the protrusion measured one-half inch from the labial SI 802 ORTHODONTIA. surfaces of the upper incisors to the lingual surfaces of the lower incisors, and the relations of the two dental arches in occlusion was such that it was almost impossible to masticate the food. (See Fig. 712.) The loss of several teeth from each lateral half of the mandible left spaces in which considerable resorption of the process had taken place, and from which it was thought advisable to cut comparatively uniform sections of the mandible, and readjust and unite the anterior and posterior sections. Fig. 709. Previous to operating. Angle's fracture bands were fastened to the teeth on either side of the area from which the sections were to be cut, by a dentist who was called in consultation. The operation was performed on May 20, 1907, at Harper Hospital, Detroit. Ether was administered, and the incision made in the soft tissues under the lower border of the body of the mandible. The soft tissues were separated from the buccal and lingual surfaces of the bone in the region to be resected, and the mucous membrane was detached from the alveolar process with a curved bistoury, care being taken not to make the slightest entrance into the oral cavity. TREATMENT OF CLASS in. 803 A trapezoid shaped piece was then resected from the mandible with a circular saw driven by an electric engine such as is used for tre- phining. In repeating the operation upon the other half of the man- dible, the old style chain saw was found to work much easier and took considerable less time. A Deschamps aneurysmal needle was used to lead the saw around the mandible. The base of the resected pieces was about one-half inch in length and somewhat longer than the apices. Fig. 710. Fig. 711. Holes were drilled through the lower edges of the remaining seg- ments of the mandible, the segments were adjusted together, and silver wires were inserted from one segment to the other on each side. After suturing the external wound, the union of the segments was made more secure by the ligating of the buttons upon the fracture bands within the mouth, from the teeth on the anterior segment to those upon the posterior segments. The entire operation, with the exception of the ligation of the fracture bands, was performed outside of the mouth, so as to make it as aseptic as possible. The patient made a quick recovery, being in the hospital about one week, the wound healing by first intention. The after-treatment model in Fig. 713 and profile in Fig. 714 show a marked improvement over former conditions. Ballin remarks: "In the first place, strict asepsis should be a 804 ORTHODONTIA. condition without which successful work is impossible. Therefore, opening of the oral cavity during the operation should not occur as this would certainly lead to suppuration and non-union of the bones. If the teeth are extracted during the operation, communication between the external incision arid the extraction wound will always take place. I would recommend, therefore, to extract the teeth necessary to be Fig. 712. removed for the resection, first, and then wait some months until the extraction wound is completely healed and atrophy of the alveolar proc- ess has taken place." In commenting upon this operation, the author believes that Ballin has solved the difficulties in the way of preventing the in- TREATMENT OF CLASS IV. 805 ception of septic conditions, in operating entirely external to the oral cavity. One suggestion made by Angle in regard to preparation for this operation seems an improvement in the technic and that is the re- section of the previously made plaster cast of the mandible, and re- adjustment with the upper cast for the purpose of obtaining the best occlusion, and cutting out a section of the mandible which most nearly approximates the plaster section which was removed. In this way, the lines of direction for the chain saw might at least be approximated Fig. 713. Fig. 714. more perfectly than without any measurements, and the mandible better adjusted for occlusal relations. In any event, the co-operation of surgeon and orthodontist seems advisable in working out the details of double resection of the man- dible in order that the peculiar skill and experience of each may serve the purpose of obtaining the most beneficial and scientific results. PART XL TREATMENT OF CLASS IV. Diagnosis of Class IV. — ^The characteristics in occlusion of Class rV being a mesial occlusion upon one lateral half, and a distal occlusion upon the other lateral half of the dental arches, as observed in the classi- 8o6 ORTHODONTIA. fication chart, the indications for treatment are a distal shifting of the occlusion on one side, and a mesial shifting of the occlusion on the other side of the arches. These movements may be secured at the same time by operating upon each lateral half as if they were independent of the other in their mesio-distal relationship, making use of the intermaxillary force as indicated by the attachment of hooks and elastics in Fig. 715, the elastic extending from a hook upon the upper expansion arch upon one side to the distal end of the tube on the lower molar clamp band, and from a hook upon the lower expansion arch to the distal end of the buccal tube on the upper molar clamp band upon the other side. Fig. 715. The cases presenting with Class IV characteristics are so rare that they are seldom reported. The few cases that have been reported have been treated as described with a fair degree of success. PART XII. THE PROBLEM OF EXTRACTION. Extraction of the teeth of either deciduous or permanent set in orthodontia, must be viewed from a different standpoint than in general dental practice, since the whole aim of the orthodontist is the restoration of the dental arches in occlusion with the full comple- ment of teeth, while the dentist is intent upon the restoration of contour, etc., of the individual tooth. If the general practitioner could see his work through the light of occlusion, articulation and development, all of his cases for bridge- work would be sent to the orthodontist for restoration of normal THE PROBLEM OF EXTRACTION. 807 sized arches, and the regaining of spaces partially or completely, from which teeth have been extracted. The radical departure from the older methods of treatment by the "new school" of orthodontia in the adoption of conservative methods of treatment, bases its assurance of propriety upon the premises that in the attainment of the normal and ideal in occlusion, all of the dental organs must be preserved in the correction of malocclusion. This arbitrary standard is not made by the specialist, but it is indicated by the perfection of the occlusion in the normal and ideal, in which is recognized the value of the individual tooth as a factor in the preservation of the integrity and regularity of the arches of teeth, the loss of one or more teeth from either arch causing deformity to just the degree of extraction which is resorted to. Fig. 716. With this conception of treatment in orthodontia, extraction as a beneficial procedure, that is, towards restoring the normal in occlu- sion, is of course absurd, for with extraction comes mutilation of the arches, impairment of speech and mastication, and the formation of lines of inharmony in the face which are surely not desirable as a result of the efforts of the orthodontist. A very large per cent, of the deformed arches of teeth which present to the specialist, are caused by the premature extraction of deciduous teeth, or the unwise extraction of permanent teeth. A very firequent question asked of the specialist by parents is as to the advisability of extraction of one or more of the deciduous teeth in the mouths of their children to "make room" for the permanent teeth. The acquiescence by the dentist in the unwisdom of this falla- 8o8 ORTHODONTIA cious and pernicious idea has led to the wholesale extraction of decidu- ous teeth in the vain hope that the space thus created will allow the permanent teeth more room to erupt. The result of such operations is just exactly the reverse of that which is intended, for the dental arch instead of being any larger, becomes still more contracted through the contraction of the space of the lost deciduous teeth, and the permanent teeth have less room to erupt than if none of the deciduous teeth had been extracted. Results of Extraction of Deciduous Laterals. — For example, in the cast on the left of Fig. 716, the deciduous lateral incisors were re- moved in the belief that the two permanent centrals would have more room for eruption, as they were apparently crowding somewhat in their effort to erupt. As a result of this treatment, the centrals erupted almost perfectly in alignment, but it will be noticed that their distal angles are almost in approximation with the deciduous cuspids, Fig. 717. and that there is no space left for the eruption of the permanent lateral incisors, necessitating an operation for the restoration of these spaces and anterior development of the arch as seen in the cast on the right of Fig, '716, the deciduous laterals immediately erupting upon being released from imprisonment. Results of Extraction of Deciduous Cuspids. — A Class I case, in which the lower deciduous cuspids have been prematurely ex- tracted, with the complete loss of their space and anterior arrest of development in consequence, is illustrated in Fig. 717. The lower incisors, having lost their support in the cuspid region, have become inclined lingually, and the upper incisors have been THE PROBLEM OF EXTRACTION. 809 Fig. 718. 8lO ORTHODONTIA. forced back against the lower incisors through the pressure of the lips and abnormal function. The treatment of this case was undertaken at the time it presented with this condition of occlusion, and both arches were expanded, in the lower, the cuspid spaces being regained, as shown in the casts at the top of Fig. 718, and in the upper, the centrals moved forward, and the space for the right first deciduous molar regained, as shown in the casts in the lower part of Fig. 718, and this relationship estab- lished through proper retention until the eruption of the permanent cuspids and bicuspids. A very noticeable improvement in the profile through this treat- ment may be seen in the central portion of Fig. 718, showing that the harmony of the facial lines is effected by such apparently slight arrest Fig. 719. of development as is caused by the loss of the lower deciduous cuspids and an upper deciduous molar. Result of Extraction of Deciduous Molars. — The model on the left in Fig. 719 exhibits a case in which the lower deciduous molar was prematurely extracted, the subsequent closing up of its space, and arrested anterior development of the lower arch, with the dropping lingually of the upper incisors in an attempt on the part of Nature to obtain a contact occlusion with the lower incisors. The model on the right illustrates the case after the space has been regained for the extracted molar, the arches harmonized anteriorly in occlu- sion, and a band and bar retention attached from cuspid to first molar in the lower arch, pending the eruption of the permanent bicuspids. The loss by extraction of any of the deciduous teeth has a similar THE PROBLEM OF EXTRACTION. 8ll destructive effect upon the occlusion, the difference being only in degree. Evil Effects of Extraction of Permanent Teeth.— In the loss of teeth by extraction from the second dentition, somewhat similar effects upon the dental arches are observed as those produced by extraction or premature loss of the deciduous teeth. Successively, the results of extraction of one or more of the perma- nent teeth are the destruction of the integrity of the dental arches, the destruction of occlusion and articulation, and finally the marring of the facial lines. The extent of the deformity is usually proportionate to the degree of the extraction, every additional tooth lost causing just that much more aggravation of conditions and change to the abnormal. Relative Value of First Permanent Molars. — In view of the prevalency of the extraction of the first molars it may be well to con- FiG. 720. sider first their relative value and then the result of their extraction from the arch. Some of the more important reasons for their preservation in the arch are as follows: 1. They are the first of the permanent molar teeth to erupt, and during the period of shedding of the temporary dentition, afford the broadest and best masticating surfaces in the mouth. 2. By reason of their great size and strength, they are the only teeth that can serve as a means of preserving the normal relationship between the dental arches, and consequently the symmetry of the face, at a time when no other of the permanent teeth, except the in- cisors, are erupted to occlusion. 3. Their presence is an aid in the forward development of the mandible. 8l2 ORTHODONTIA. 4. Statistics comparing the relative frequency of caries in the first and second molars prove the second molar more often carious than the first. 5. The first molar, on the average, is a better constructed tooth than either the second or the third molar. 6. Its extraction is the cause of a large percentage of cases of malocclusion, and consequent facial inharmony. Results of Extraction of First Permanent Molar. — The history of the case of malocclusion in Fig. 720 dates its inception to the time of the extraction of the lower right first permanent molar, and the series of intricate changes in occlusion to the abnormal are commonly observed. The model on the right of the cut represents the left side of the case in occlusion, exhibiting normal cusp relationship of upper and lower teeth as far forward as the cuspid. Fig. 721. The model on the left illustrates the destruction of occlusion and the shortening of the right lateral half of the dental arch as a result of the extraction of the first molar. To the student of occlusion, the changes in occlusal relations after the loss of the first permanent molar are more or less familiar, and it is comparatively easy to follow the consecutive stages whereby the ruination of otherwise beautiful dental arches has been accomplished. Consequent upon the loss of the first molar in this case, ensued not only the tipping mesially of the second molar, but also the drift- ing distally of the second bicuspid into the space, followed by the distal movement of the first bicuspid, the cuspid and incisors, and the contraction of the whole arch. THE PROBLEM OF EXTRACTION. 813 The effect of this contraction upon the upper arch is noticeable in the lingual positions of the incisors, and the torsion of the right lateral incisor. The closing together of the teeth in occlusion tends to force the lower right second molar still farther mesially, and to draw the right lateral half of the lower arch distally to a considerable extent. The occlusal views of the upper and lower arches in this case in Fig. 721, illustrate from this aspect, the mutilated arches, both being contracted and the upper arch flattened in the incisor region, produc- ing a similar effect in the facial profile, as a consequence. The author has observed a patient with a similar case of maloc- clusion, who was on the verge of nervous collapse as a result of suck Fig. 722. changes in occlusion as to make mastication painful and almost im- possible. Result of Extraction of Second Bicuspids. — A variation from these changes in occlusion as a result of the extraction of a lower second bicuspid is observed in Fig. 722. Although not revealed by the picture, the second bicuspid on the right side of the lower arch was also extracted so that the change in occlusion was comparatively uniform bilaterally. The loss of these teeth has caused an apparent protrusion of the upper arch in Fig. 722 as a result of the perversion of function of the occlusal planes and also of the lips, the lower lip tending to roll up under the upper incisors and force them still farther outward. The first and second molars in occlusion have retained the normal mesio-distal relationship of the arches, and the contraction of the 8 14 ORTHODONTIA. lower arch has been entirely anterior to the first molars, the second bicuspid spaces being almost entirely closed. Complications in Treatment after Extraction of Teeth. — The treatment of cases of malocclusion caused, or mutilated, by ex- FiG. 723. traction of the permanent teeth, is necessarily much more complicated than if the full complement of teeth were present, so that complete arch restorations as well as occlusal relations might be established. As a rule, it is imperative that all spaces of teeth which have been lost through extraction should be restored and artificial substitutes Fig. 724. inserted in order to secure harmony in occlusion between the dental arches. In the cast on the left of Fig. 723, it will be noticed that the lower right lateral incisor is missing, it having been extracted for the pur- THE PROBLEM OF EXTRACTION, 815 pose of "regulating" on account of its having been located in lingual occlusion. In the restoration of this arch to normal size, the space for the right lateral was regained, as shown in the cast on the right of Fig. 723. How much more scientific it would have been to have enlarged this arch to this extent when the case first presented with the lateral in lingual occlusion and to have restored it to its normal position in FiG- 725. {Gough.) the arch. Here, indeed, is the clue to the proper solution of the case and illustrates, in a nutshell, the impropriety of extraction either "to make room" or correct alignment. The before and after treatment models of the case viewed from the front in Fig. 724 illustrate the necessity of regaining the space for the lateral incisor and providing an artificial substitute in order to restore the normal relations of occlusion. If the upper arch only had been restored to its normal size and 8i6 ORTHODONTIA. shape, it would have been larger than the lower by the width of the missing lower lateral incisor. The illustration of a few practical cases in pairs, of the same class, one of the pairs having been treated by extracting, the other by restor- ation of normal occlusion, may serve, by comparison, to show the relative value of the two methods of treatment. Fig. 725 exhibits a Class I case in which the dentist, who originally had it in charge, before referring it to the orthodontist, thought it neces- sary to extract the upper first bicuspid on the left side in order to " make room" for the eruption of the left upper cuspid which was formerly in a position similar to that of the right cuspid seen in labial occlusion in the model on the left of the cut. Fig. 726. The operation of extraction was performed as indicated, the upper left cuspid erupting into the space, partially, but so incompletely filling it that the patient was unwilling to have the same thing done upon the right side of the arch. On examination of the occlusal view of the upper and lower casts in the same cut, it will be observed that the lower arch is contracted anteriorly, the cuspids being in torso-occlusion, and if an operation for expansion of both arches had been performed, normal occlusion could have been obtained. Fig. 726 illustrates a precisely similar case, both as to etiology and diagnosis, except that the malocclusion is limited to the left lateral half of the arches. The prognosis in cases of this kind is always favorable to treat- THE PROBLEM OE EXTEACTION. 817 ment without extraction, and the diagnosis assures such splendid results as are shown in the after treatment model on the right of Fig. 726, the arches being restored to normal size and shape, and normal occlusal relations being established. Fig. 727. Fig, 727 exhibits a somewhat more severe case than the one just described, and it might have been governed by the same laws in its treatment if thev had been understood. Fig. 728. Two mistakes were made in the treatment of this case, however, one by the extraction of the upper second bicuspid, the other the neglect of the slight irregularity in the lower in the treatment of the case. The after treatment model on the right shows alignment to a 52 8i8 ORTHODONTIA. certain degree but it will be noticed that the arch is still crowded, and that the possibility of harmonizing the arches and restoring occlusion is forever lost. All that was needed was the regaining of some lost space in the lower arch and the harmonizing of the upper arch to it, saving all of the teeth. Fig. 728 illustrates a similar case in which the ideal has been attained in the restoration of normal occlusion without extraction, each occlusal plane having been moved into its correct relationship with its antago- nist of the opposite arch, and the production of a harmonious result which is truly beautiful. These results were obtained some fifteen years ago when the principles of occlusion were much less known than now. Fig. 729. Coming now to another class of deformities in which extraction of one or more of the bicuspids has been advised as of value in the reductions of protrusions such as is here illustrated, Fig. 729, let us note in the case the results of such extraction upon the arch. The first bicuspid was extracted and the anterior teeth drawn distally until the space of the extracted tooth was closed, a very common operation extant among the profession for the correction of this deformity. The model of the completed case on the right exhibits no such harmony of contour as the models of the completed cases which are illustrated under the treatment of the first division of Class II. The curves are not graceful, the mutual support of the full complement of THE PROBLEM OF EXTRACTION. 819 teeth has been lost, and a lame and crippled appearance is distinctly noticeable. In the majority of cases in orthodontia, extraction of the teeth is not indicated, in fact, an almost iron clad rule has been established by some specialists operating from the basis of occlusion, condemning extraction in all cases. While this rule is a safe one to follow in the majority of cases, to attempt to practise it in every case would be entirely unwise, as there are cases in which it is not only impossible to restore normal occlu- sion, but in which extraction is indicated in order to obtain any sort of harmony of the occlusion. These exceptions do not necessarily lower the standard of perfec- tion which the restoration of the normal or ideal in every case might imply, since their very existence and the difficulty of their diagno- sis should, in the nature of things, compel the operator to use his best judgment and follow a safe rule. In what cases, then, is extraction advisable ? The answer to this question is the knotty part of the problem, for although we are cer- tain of the advisability of the procedure in some cases, to lay down a set rule for such cases would militate against the best results which might be obtained without extraction, for in two identically similar cases, extraction may be found necessary in one, while in the other, the restoration of the ideal in occlusal harmony may be easily diagnosed and obtained. Exceptions to the general rule of occlusal restoration in which it is advisable to extract does not give license to extract promiscuously, and the only hesitation which the author feels in attempting to point out these exceptions lies in the possible exaggeration of the number of cases in which the novice, because of his lack of experience, and the un- scrupulous dentist, because of his indifference, might feel justified in ex- tracting teeth unnecessarily because of any loophole which the knowledge of an exception to the general rule of non-extraction might give them. But in the publication of a scientific work on orthodontia, which, to be scientific and most helpful to the general practitioner, should not be misleading, the obligation laid upon the author is so great, that to attempt to encourage the attainment of impossible results through non-extraction and futile attempts at occlusal restoration, would defeat the object of the promulgation of the truth which should be paramount in the building up of any science which tends in any way to benefit the human race. It might be correctly stated that extraction is advisable in some 820 ORTHODONTIA. few cases in which it is impossible to obtain a satisfactory result after an intelligent and persistent effort in following out the laws of occlusal restoration. Or, in cases of monstrosities of tooth dentition, such as in extreme hypertrophy of the alveolar processes, where restoration of normal occlusal relations would only exaggerate the deformity and increase the inharmony of facial contour. In cases already mutilated by extraction, in which it is not advisable to restore normal occlusion by regaining all spaces lost by such extrac- tion, it may be necessary to extract according to the requirements which are peculiar to the individual case, and for which no set rule may be established. So seldom is extraction indicated that in the author's practice, it has been resorted to in but six cases in fifteen years, and a similar record will be found in the practices of other specialists operating from a conservative basis. In these cases, the advice of a specialist of at least five years' ex- perience in orthodontia ought to be sought, in order that an error in judgment may not be made through simple lack of experience. PART XIII. RETENTION. The Object of Retention. — ^A clear perception of the field of re- tention necessitates a proper understanding of the ultimate purpose of the treatment of arrested developmental conditions in the dental arches, which is the restoration of function, through the stimulation of struc- tural development in the maxillary arches, and the attainment of the normal in occlusion and articulation. It will be inferred from this statement that the development and restoration of the normal in shape and size of the individual dental arch is the primary, and the attainment of normal positions of inclined planes of antagonizing cusps of occluding teeth the secondary, con- sideration. in treatment, these two phases being so related, however, that the consideration of the one without the other would be incom- prehensive of the scope of orthodontia. Necessity for Retention. — ^In the dental malocclusions of the child from six to ten years of age, the rapid restoration of function through orthodontic treatment is so aided by this stimulation to normal growth that the retention of these cases is a matter of a few weeks or months only, except in cases of distal occlusion and its accompan)dng RETENTION. 82 1 ack of vertical development of the dental arches, or in cases of infra- occlusion in the incisor region. Expanded arches of these early undertaken cases need to be retained only until the eruption of permanent incisors, cuspids or bicuspids, according to the age treatment is begun. Incisors which have been rotated during or soon after eruption need but a few weeks' retention before the rapidly developing alveolar process and the fibers of the peridental membrane accommodate themselves to new conditions of resisting tendencies to displace these teeth from their new positions in normal occlusion. In the more mature cases, the resistive qualities of the osseous structures in which the teeth are implanted, and of the fibrous elastic membranes with which they are surrounded, are in evidence until long after treatment is completed, and unless these reactive forces are inhibited for varying periods after the completion of treatment, more or less of a return of former conditions of imperfec- tion of form, and of occlusal relations of the dental arches is inevitable. Added to these untoward influences the possible abnormal habits of mouth-breathing, thumb- and lip-sucking, and the abnormal tension of the muscles of the tongue, lips and cheeks, and the abnormal influence of inclined cusp planes present in many cases, the forces which tend to resist normal development and function may be considerable. Hence it is that retention is really a passive or at least a less active stage of treatment, and success in treatment is only assured when reten- tion is carefully provided for. Retention may he defined as the maintenance of such development of the dental arches and relations of occlusion as may have been established through treatment, by a proper antagonism of any forces which may in- terfere with these normal structural and functional conditions. The establishment of mechanical resistance to these return tend- encies through appliances attached to the teeth must be sufficient so that an equilibrium between the forces of reaction and the applied resistance is obtained. An insufficiency of resistance in a retaining appliance would result in a partial return of former conditions. Retention, then, as in anchorage, is a measure of resistance values, the proper appreciation of which is essential to the permanence of results obtained in treatment. Length of Retention. — Usually the retention of a corrected mal- occlusion is a matter of more than a few weeks in point of time, many cases requiring months, and some of the more severe, several years of fixation in order to overcome the resistance of the fibers of the peridental membrane, and the tendency of the arches to contract or assume their 822 ORTHODONTIA, original forms and relationships after having been restored to a normal condition of occlusion, or after being mechanically developed up to a physiological limit. The retention of the deciduous teeth is a process of temporary fixation for the development of the arch alone, v^hlle the retention of the permanent teeth is often a necessity for their maintenance in their relative positions in the arch, although developmental changes are still going on. The length of time of retention of the arches of deciduous teeth, at the most, can only last until the eruption of the permanent teeth, in whole or in part. Permanent teeth, which have been moved into their normal lines of occlusion during eruption or immediately after, need retention for a far shorter time than if they have been confirmed in their abnor- mal positions for some time before being corrected. It is a well known fact in orthopedic and orthodontic practice thai the rapidity of the restorative or building up process in bony tissues, as after setting of fractures, is proportionate to the degree of fixation of the parts during the period immediately following the corrective operations. To the end, therefore, of shortening the time of retention, as well as obtaining a more perfect development and greater strength of the tissues surrounding the moved teeth, and avoiding the possibility of any loss from contraction of arches after expansion or regaining of spaces, the fixed retaining appliance, with cemented bands, is gener- ally to be preferred to any other. Retention Classified. — Retention may be classified as follows: Occlusal, simple, reciprocal, intermaxillary, and occipital, according to the quality of resistance used in opposing the reactive forces, or the return tendencies. Of especial importance is the influence of the inclined planes of the cusps in retention, their normal function ending in occlusion and articulation, to preserve the integrity of the arches. Occlusal retention is the maintenance of the normal occlusal posi- tions of the teeth, individually or collectively, through the normal functional influence of the inclined planes of the cusps, and the contributory forces gained through restoration of arch integrity. In order to secure the harmonious working of the inclined planes it is necessary that not only should the full complement of teeth be present, preserving individual arch integrity by proximate contact, but that the normal size and shape of the arches be restored, which would include the restoration of articulating planes and compensating RETENTION. 823 curves, etc. Experience will prove that articulating planes can be only approximately obtained in the correction of malocclusion, so compli- cated is the mechanism of articulation, and the lack of development of the arches in malocclusion so disturbing the harmonious working of the laws of articulation that accurate arch and cusp protection in articular movements is outside the range of possibility of treatment, except in special cases. In malocclusion there is abnormal function of occlusal inclined planes of cusps, often deficient respiratory mechanism, and tongue or lip insufficiency, and abnormal muscular pressure, which, if not corrected will still continue their abnormal influence upon the arches of teeth. The nearer the approach to normal occlusion and articulation in the treatment of any case of malocclusion, the less need will there be for mechanical retention beyond that afforded by the normal action and reaction of the inclined planes of the cusps. It must be remembered however, that the restoration of the normal functions of occlusion and articulation does not counteract the tendency of the fibers of the peridental membrane and the alveolar process to assume their former relations of abnormality, except to a slight degree, otherwise there would be very little need for mechan- ical retention of teeth and arches. The normal relations of occlusal inclined planes in the attainment of normal occlusion, cannot he depended upon alone, for retention, until after varying periods of fixed retention of the teeth and arches with mechanical appliances, except in simple and special cases. An upper incisor tooth, moved from lingual to normal occlusion, if there is sufficient overbite, will be retained by the action of the lingual incline of the upper incisor upon the labial incline of the lower incisor. The same effect will be observed where there is sufficient overbite in any of the upper teeth which have been moved into their line of occlusion from lingual occlusion and restored to the normal action of the inclined planes. To a lesser degree, also, the restoration of upper bicuspids and molars in buccal occlusion, lower incisors and cuspids in labial occlusion, and lower bicuspids in lingual or buccal occlusion, will be retained by the restoration of the normal influence of their inclined planes in occlusion. Infra-occlusion of the teeth, on the other hand, demands long and persistent retention of corrected occlusion. Also, teeth which have been rotated, unless at a very early age, as 824 ORTHODONTIA. during their eruption, will need retention by mechanical appliances for varying periods of time. Again, anterior and posterior expansion of arches will usually need retention for periods of time varying according to the degree or extent of the expansion, the age of the patient, the peculiarities of the case, etc. Extensive cases of Classes II and III, will always demand a very persistent mechanical retention, often for several years. Simple cases of Class II, especially of the second division, and its subdivision, and of Class III, are often retained by normal cusp in- fluence alone, as far as the mesio-distal relations of occlusion are concerned. Fig. 682 is an example of bilateral distal occlusion, Class II, Div. 2, which was retained in its mesio-distal relations entirely by the interdigitation of the cusps of bicuspids and molars, although the upper incisors were retained by bands and spurs for a short time. Auxiliary Occlusal Retention is the maintenance of the normal occlusal relations of the individual teeth, or of the dental arches as a whole by means of auxiliary occluding inclined planes. Examples of auxiliary occlusal retention are seen in the auxiliary cusps on cuspid bands for retention, the lingual inclined planes on upper incisor bands, or on lingual arches, and the spur and plane retention of Class II and Class III. Simple retention is the antagonism 0} the forces of reaction by the resistance of one or more teeth, in the same arch , which afford a compara- tively stable resistance in opposition to these forces. Fig. 730. For example, in Fig. 730, A, the central incisor which was in lingual occlusion is retained in position by cementing upon it a band with labial spur extending over the labial surface of each adjoining tooth, as shown at B in the same figure. The adjoining teeth may have shared in a general expansive movement to a slight degree, but would still afford a comparatively stable resistance for retaining the lingual tendency of the central incisor which was in lingual occlusion. A torso-mesial occlusion of the one central may be retained by the cemented band and lingual spur over the lingual surface of the other central which may, or may not have been moved to a slight ex- RETENTION. '25 tent labially or lingually. An absolutely stable resistance in single tooth movements is, of course, to be preferred for retention purposes. Reciprocal retention is the counterbalancing oj the return tendencies of two or more teeth in the same arch or in opposite arches by the antago- nism or opposition oj their reactive forces. Simple reciprocal retention would be represented by the antago- nism of the reactive tendencies of two teeth which have been moved in opposite directions, as illustrated in Fig. 731, the two centrals being Fig. 731. rotated in opposite directions, and the retention consisting of two bands soldered together, and cemented upon the centrals. Another example of simple reciprocal retention is illustrated in Fig. 732, the lateral incisor and first bicuspid being reciprocally an- tagonized in their return tendencies by the band and spur method. Compound reciprocal retention would be represented by the antago- nism of the tendencies to return of several teeth in the same or opposite arches. Fig. 732 In Figs. 733, 734 and 735 are illustrated various methods of securing simple and reciprocal retention. For example, in B, Fig. 733., the rotating tendency of the central incisor may be antagonized after correc- tion by simple retention by means of labially and lingually placed spurs on a cemented band as in C, Fig. 733. In D, Fig. 733, the tendencies of the mesial angles of the two centrals to rotate in opposite directions may 826 ORTHODONTIA. be counteracted by simple reciprocal retention as in E, Fig. 733, by a spur from the mesial angle of one central band to the other, simple retention would be here represented by the labial and lingual spurs extending from the central bands to the adjacent laterals. At F, Fig. 733, is shown a variation of simple retention in the use of spurs from the central bands bent over a lingual arch, as suggested by Lourie. Fig. 734 exhibits at GH and KL the application of compound recip- rocal retention by the use of bands and spurs. In Fig. 735 compound F Fig. 733. reciprocal retention is illustrated in the use of spurs from the central incisor bands attached to a lingual arch, which assists in retaining the lateral incisors at the same time. Intermaxillary retention may be compound reciprocal retention between teeth of opposite arches when properly provided for. In the retention of the expanded arch, as in Fig. 739, the resistance of one lateral half is pitted against that of the other, and is an illustra- tion of compound reciprocal retention. G H K Intermaxillary retention consists of the continuation of the use of intermaxillary force in cases of mesial or distal shifting of occlusion in such a manner that a reciprocation of force and resistance is established RETENTION. 827 which is capable of the retention of the mesio-distal chattges in occlusion. In adult cases or in "mixed dentures" of Class II or III, the necessity for the use of the intermaxillary force for a considerable time after treatment, in order to retain the normal mesio-distal re- lations of the dental arches, or the restored occlusal planes, is evident to the experienced orthodontist. This form of retention is especially applicable in cases of the first division of Class II and in Class III. Intermaxillary retention is also of great value in upper protrusions of Class I. ^Occipital retention consists of a continuation of the wearing oj the headgear and traction bar or chin cap for counteracting the resistance offered by the lower dental arch or the mandible after treatment of mesial occlusion or of infra-occlusion with occipital force and anchorage. Occipital retention is seldom used except in cases in which the chin cap has been used in connection with it for correction of severe cases of M N Fig. 735. mesial occlusion or of infra-occlusion of the anterior teeth. After the use of the headgear for treatment in Class II or Class III, intermaxillary retention is usually substituted as being sufficient to retain the mesio- distal changes in occlusion. Field of Retention. — i . In the simpler cases of malocclusion where the arches are in normal mesio-distal relation, the dental arches being fully developed, and the overbite normal, the retention of corrected slight malpositions of individual teeth is all that is necessary. The usual case, however, presents with a complication of malocclusions, necessitating retention of expanded arches and individual tooth malpo- sitions, often with infra-occlusion or supra-occlusion, requiring a change in the occlusal plane and its retention, and occasionally still further com- plicated by a distal or mesial malocclusion requiring particular methods of retention. 828 ORTHODONTIA. In general, then, the field of retention may be divided as follows: i. The retention of corrected malocclusions of individual teeth; 2, reten- tion of expanded arches; 3, retention of changes in the occlusal plane; 4, retention of mesial or distal changes in occlusion. Retention of Malocclusion of Individual Teeth. — In the reten- tion of malocclusions of individual teeth, the age of the patient and the length of time the teeth have been in malocclusion must be considered. Incisors moved from lingual to normal labial positions need no reten- tion other than the occlusal retention of the cusps. Occlusal retention may also be depended on for the retention of cuspids, bicuspids and molars moved from lingual occlusion to normal if the malocclusion is not one of loner standing. Teeth which have been erupted but a few months^ such as incisors in torsal occlusion, need but a few weeks' retention. In more advanced cases in which the permanent teeth are all erupted, ':orrected lingual positions of incisors in Class I need only natural occlusal retention. Corrected torsal positions of incisors in these cases, however, need a persistent simple or reciprocal retention as in Figs. 731 and 733 for at least one year. FiG. 736. Retention after Bodily Movement of Teeth.— Again the reten- tion of teeth which have been moved bodily must be of a different nature than that of teeth moved by inclination movement. At the present writ- ing the best method of retention after bodily movement of teeth is a continuation of the wearing of part of or all of the appliance which was used to effect the bodily movement. In some cases the author has used a portion of the .30-in. arch wire with vertical pins locking in tubes as in Fig. 736 to retain the positions of the four incisors which have been moved bodily. Various combina- tions of this nature will suggest themselves to the operator. Retention of the Expanded Arch.— The age at which treatment is begun, and the number of permanent teeth erupted, will necessarily require a variation of forms of retention according to the demands of the individual case. If uniform development of the dental arch has occurred during treatment, that is, the arch being expanded in the molar as well as the RETENTION! 829 cuspid region, the retention will have to be so applied that this expan- sion will be uniformly retained. In many cases, however, only the anterior portion of the dental arch is developed, hence, the retention of the entire dental arch is unnecessary. The earliest indication for retention in the deciduous arch is after a certain amount of expansion of the anterior portion of this arch for securing development enough for the eruption of the incisors and cus- pids, and possibly the bicuspids. The need for a fixed retention of a part of the deciduous arch, during a varying period of natural development and including the eruption of some of the permanent teeth is therefore apparent. Fig. 737. Retention of Anterior Part of Developing Arch. — An appliance which will efifectiially retain the anterior part of the arch during the developing period and which is attached entirely to the deciduous teeth, is shown in Fig. 737, being the retention of the anterior part of the ex- panded arch shown in Fig. 620, The deciduous cuspids are banded and connected by a lingual wire of 18 or 19 gauge, B. & S., and short spurs are extended distally from the lingual surface of the cuspid bands upon the lingual surface of the deciduous molars. A great amount of strength in a retaining appliance attached to the deciduous teeth is never necessary because of the slight resistance they oflFer to the action of force appliances in their movement, due to their small short roots, and the cartilaginous nature of the al- veolar process. 830 ORTHODONTIA. If more development of the anterior portion of the arch is re- quired after the expansion has been carried on as far as possible, the retainer may be constructed as in Fig. 738, in which the lingual wire slips into short tubes soldered to the cuspid bands, and by pinching with the wire stretching pliers, as suggested by Angle, the arch may be still further expanded in this region during the period of retention. The lingual wire in this case should be constructed of platinized gold sufficiently soft to be easily stretched in this manner without breaking. Retention of the Entire Deciduous Arch. — In case that the deciduous arch has been uniformly developed by expanding anteriorly and posteriorly, an immediate need exists for the retention of all the increased width and length of the arch which has been gained in the treatment. Fig. 738. Fig. 739. To illustrate, the upper arch in Fig. 623, although the permanent central incisors and first molars are present, is still the same in width as the deciduous arch, and in development is still a de- RETENTION. 831 ciduous arch. The central incisors being .39 inch wide, require, according to the Hawley measurements, an arch considerably larger than the average. Having been expanded during a period when the deciduous teeth present were comparatively firm in their attachments, the crowns of the permanent teeth being moved laterally through their envelopment by the roots of the deciduous molars, the indicated retention in the case is a fixed retention of the entire deciduous arch until such time as the natural developmental processes have been completed so that the eruption of the remaining permanent teeth may take place in a sufficiently enlarged arch. According to these indications, the retention exhibited in Fig. 739 was ad- justed, bands of iridio-platinum being fitted to the deciduous cuspids and second molars, and connected by a lingual retaining wire of 19 gauge, B. & S., iridio-platinum, soldered to their lingual surfaces, and extending across the lingual surfaces of the first permanent molars. In order to secure a more accurate fit, the lingual wire was adjusted Fig. 740. Fig. 741. and soldered to the bands upon the plaster cast, the bands having been removed with the impression. The central incisors were retained with two iridio-platinum bands united with solder, and cemented in position. A slight lateral spring may be given to the lingual retain- ing wire to assist in further stimulus to lateral development of the arch if necessary. 832 ORTHODONTIA. Retention of Anterior Portion of Permanent Arch. — Where the permanent arch has been expanded anteriorly, it is essential that the increased width of the arch should be retained for some time, so as to allow the development of the alveolar process and the overcoming of the forces of reaction. For example, if the arch has been expanded ante- riorly to allow the centrals or laterals to be rotated, etc., the retention of these individual teeth in their lines of occlusion is not sufficient in most cases, as the reactive force in the contractive tendency of the arch will soon cause a malocclusion to appear, such as the overlapping or torsion of one or more of the incisors. Fig. 742. It is advisable, therefore, to always retain the arc of the six anterior teeth by means of a fixed retaining appliance which will hold the width, gained between the cuspids, such as is shown in Fig. 740, adding a lingual spur to the first bicuspids when they have also been included in the lateral expansion. Fig. 741 illustrates the expansion and retention of the anterior por- tion of an upper arch, in which space was made for the eruption of the cuspids. Bands were cemented upon both of the first bicuspids, these bands having previously been united with the strong 18 gauge bar of plati- nized gold extending along the lingual surfaces of the incisors, and having spurs of 21 gauge gold wire bent around the distal angles of the lateral incisors to the labial surfaces to hold the four incisors intact. RETENTION. 833 This appliance is as simple and esthetic as can possibly be con- structed for a case of this character, and it might well be used as a standard retention for similar cases in which no rotation of teeth is necessary in the incisor region. The Lingual Arch Retainer. — The use of the Ungual arch re- tainer, as suggested by Lourie, invites many possibilities of prac- tical and esthetic retention of the dental arches, because of its efficiency and inconspicuousness. Consisting, as shown in Fig. 742, of a gold and platinum or an iridio- platinum wire closely adapted to the lingual surfaces of the incisors, cuspids, and bicuspids, and attached distally to the ends of the lingual screws or lingual surfaces of molar or bicuspid clamp bands, or to the lingual surface of plain bands, it is correct in principle since it provides for complete retention of the entire dental arch after general expansion, Fig. 743. at the same time providing for such retention of the individual teeth as may be necessary. The retention of teeth which have been moved labially or lingually, extruded or intruded, may be accomplished with this method by at- taching hooks to the lingual surfaces of individual bands upon the teeth, and bending these hooks above or below the lingual arch, and in such positions as will tend to overcome the particular resistance required. The principle of the lingual arch with lingual hooks or spurs attached is shown in Fig. 735. In Fig. 742 its use in retaining the extrusion of the incisors in a former case of open bite malocclusion is effective, especially with the spurs over the occlusal surfaces of the deciduous molars, enlisting their resistance in supporting the lingual arch in position which in this instance is attached to clamp bands upon the deciduous molars. In Fig. 743 the lingual arch presents a feature of additional value 53 834 ORTHODONTIA. in its prevention of the tipping or rotation of the teeth which sup- port the buccal spurs for retention of the mesio-distal relations of the arches. Retention of Entire Permanent Arch. — After expansion of the permanent arch laterally and anteriorly, a fixed retaining appliance which will hold the form and size of the arch may be constructed as shown in Fig. 743, the cuspids and first molars being banded and con- FiG. 744. nected with a lingual wire which supports the intervening teeth. It is advisable to construct this retaining appliance and fit it to the teeth temporarily, allowing the teeth to settle somewhat, when the appliance may be permanently fitted and adjusted. Teeth which have been rotated should be banded, and either retained by labial and lingual spurs upon the bands or by some attachment of the bands to the Fig. 745. lingual wire to counteract their return tendency. Whereas, in many of the simpler cases of arch expansion this form of retention is most excellent, yet it is somewhat faulty in construction for those cases in which the cuspids have been in labial occlusion, similar to the positions shown in Fig. 744, for with the cuspids banded and supported by the lingual wire, they are held rigidly forward, while the incisors, having RETENTION. 835 some freedom, settle back sufficiently to allow the cuspids to appear somewhat in labial occlusion. In order to obviate this difficulty, the author has constructed a retaining appliance for these cases upon slightly dififerent lines, as shown in Fig. 745. The lingual wire is attached to bands upon the lateral incisors and first molars, spurs extending distally over the labial surfaces of the cuspids, effectually retaining them in position* and allowing them to settle into their positions even more perfectly. Ini some of the simpler cases in which the cuspids are not in labial occlusion^ the lingual arch may extend from one first molar to the other with- out being attached to incisor or cuspid bands. A very ingenious and efficient retaining appliance, designed by H. A. Baker for retention of the entire arch is illustrated in Fig. 746. In effect, it is a lingual arch, KL, of clasp wire, 17 gauge B. & S.^ closely adapted to the lingual surfaces of the incisors, cuspids, and Fig. 746. bicuspids, soldered anteriorly to the lingual surfaces of gold bands upon the cuspids, with its distal ends engaging in rings upon the lin- gual surfaces of gold bands upon the molar teeth. The labial wire, F, extending from one cuspid band to the other, is designed to retain the incisors from a return to positions of torsal or other malocclusion. For greater accuracy of adaptation, this appliance is preferably made upon a cast, the four bands having been previously constructed upon the natural teeth, and an impression taken of the arch with them in position. The molar bands, M and N, are first cemented into place, and then, after filling the cuspid bands with cement, the distal arms, K and L, are slipped into the lingual rings on the molar bands, and the anterior 836 ORTHODONTIA. portion of the appliance forced into position upon the anterior teeth, there being enough play in the lingual rings upon the molar bands for this downward movement of the appliance. Retention of Changes in the Occlusal Plane. — ^The changes in the occlusal plane necessitating retention are usually those demanded after treatment of infra- and supra-occlusion. Retention of Infra-occlusion of Incisors and Cuspids. — ^A continuation of the use of the operative appliances after correction of infra-occlusion of the incisors and cuspids is often the only practical means of affecting their retention. For example, after treatment of this condition with the Angle .30 inch sectional arch with upright pins, locked in tubes on incisor and cuspid bands it is difficult to construct a retaining appli- ance that is more effective than the operative appliance, hence it may be left in position for retention. After the use of the plain expansion arch for the correction of simple cases of infra-occlusion of the incisors, as in Fig. 609, the expansion arch may be left in position for retention, or a lingual arch of .30 inch substituted, Fig. 742, the incisor bands being provided with lingual hooks which engage with the lingual arch and prevent the return of the infra-occlusion. In more pronounced cases of infra-occlu- sion of the incisors and cuspids in which the Fig 747 (C 5 Case) expansion arches have been adapted as in Fig. 650, and intermaxillary force used to correct the infra-occlusion, the continued wearing of the expansion arches with the use of very light intermaxillary elastics is essential for the retention. C. S. Case illustrates and describes one of the most inconspicuous retaining appliances, after correction of infra-occlusion in his work on Dental Orthopedia. Its adaptation is shown in Fig. 747. In the severe cases of infra-occlusion in which the angle of the man- dible has been changed by means of a specially constructed head gear and chin cap, one form of which is shown in Fig. 651, the continuation of the wearing of the head gear and chin cap affords the best means of retention of the case. Retention of Infra-occlusion of Bicuspids. — ^The retention of cases after tieatment with the light expansion arch for infra-occlusion of the bicuspids as in Fig. 608 consists in the substitution of a lingual arch extending from one first permanent molar to the other and arranged so that it will pass gingivally to lingual hooks on bicuspid bands and RETENTION. 837 occlusally to hooks on incisor bands as in Fig. 748. Although it has been claimed by some writers that there is no supra-occlusion of the incisors in connection with infra-occlusion of the bicuspids, the author regards this theory as incorrect from the observations of cases from practice in which the incisors have been intruded in their sockets as much as the bicuspids have been extruded. In this retention, then, there is a reciprocation of the resistance of the bicuspids to become intruded and the resistance of the incisors to become extruded. Fig. 748. Retention of Corrected Infra-occlusion of Deciduous and Per- manent Molars. — In Class I (upper protrusion) after the correction of the infra-occlusion of the permanent molars in a mixed denture by means of intermaxillary force exerted between the upper and lower molars, held apart by the lower incisors occluding with a bite plate as in Fig. 557, the new occlusal plane established is retained by a continuation of the use Fig. 749. of intermaxillary force with elastics exerting a very gentle pull, the rubber bite plate being worn at the same time. Retention of Mesio-distal Changes in Occlusion. — As cases of the second and third classes of malocclusion present the greatest difficulties in the way of treatment, so also do they require exceptionally diflBcult retention, for in addition to the necessity of retaining each dental arch in its corrected form and size, including the malposed teeth which have been restored to normal positions, it is almost always essential that the mesio-distal change in occlusion shall be persistently 838 ORTHODONTIA. retained for some time after treatment, varying with the age of the patient and the extent of the mesio-distal malocclusion. Retention of Class II. — In Class II, Div. i, the average case re- quires retention of expanded arches, of corrected malpositions of the in- dividual teeth, and of corrected mesio-distal changes in occlusion. Also, the corrected changes in the occlusal plane, especially v^here the abnor- mal overbite is corrected, require especial means of retention in addition. Occasionally a case presents in which the restoration of function of the occlusal inclined planes needs no other retention than the normal action and reaction of these inclined cusp planes upon each other in occlusion and articulation. A case of this kind belong- ing to the second division of Class II is described under treatment of this class and illustrated in Figs. 68 1 and 682. Fig. 750. As illustrative of the fact that mesio-distal retention upon the molars is not always necessary after treatment in the divisions of Class II, in early treated cases, Reoch reports a case in which the retention con- sisted simply of an inclined plane of gold attathed to the upper central incisors, illustrated in Fig. 664, tending by its action at each closure of the mouth to cause normal locking of occlusal planes. Antagonizing Spurs. — The simplest retention of the normal mesio-distal relations of the dental arches, after shifting the occlusion, is by means of spurs soldered to the buccal surfaces of upper and lower molar anchor bands, these spurs being so related that they act as inclined planes continually forcing the occluding molars into their proper cusp relationship during each closure of the jaws. Fig. 749 illustrates the positions of the buccal spurs for the retention RETENTION. 839 of the mesio-distal relations established after treatment of a case of Class II. The buccal spurs upon the molar bands are preferably constructed of square wire, of platinized gold or iridio-platinum, afifording flat surfaces for the antagonizing of the two spurs in occlusion. These spurs are adjusted after a method suggested by Watson, being a modification of the spur and plane method described by Angle. Occasionally it will be found that the buccal spur on the upper molar band in Class II may be dispensed with, allowing the lower buccal spur to antagonize the plane of the mesial angle of the mesio- buccal cusp of the upper first molar, especially in cases in which the permanent bicuspids are unerupted. The buccal spurs are also effectual in retaining single molar or bicuspid teeth which have been moved buccally or lingually into proper occlusion, as described by Angle. Fig. 751. Figs. 750 and 751 illustrate the right and left occlusion of a case of Class II, Div. I, before and after treatment. It is useless in cases in which the upper incisors are protruded to the extent shown in this case to expect that restoration of function of the inclined planes of the incisors will be sufficient to retain the normal relations of occlusion which have been established in the incisor region, and it is advisable to retain the mesio-distal change in occlusion until the eruption of the permanent bicuspids in a case undertaken as early as this one. A buccal and occlusal view of the retaining appliances used in this case is shown in Figs. 752 and 753, the antagonizing spurs upon upper and lower molar bands serving to retain the normal mesio-distal rela- tionship established between the arches. 840 ORTHODONTIA. The lingual arch, acting in conjunction with cemented incisor bands, attached with lingual hooks, effectually retains the upper arch in its normal form and the upper incisors in their normal positions. Fig. 752. ^Intermaxillary Retention in Class II.— (Normal Overbite.) A method involving the use of intermaxillary retention of Class II, Div i, Fig. 753. illustrated and described by Watson in 1908, is still in use with but few modifications. The upper appliance A, Fig. 754, engaging with the lower RETENTION. 841 appliance by means of intermaxillary elastics, consists of a threadless buccal arch, of 18 to 20 gauge iridioplatinum (20 per cent, iridium) sliding into close-fitting buccal tubes on first molar clamp bands, a little collar soldered to either side of the arch just in front of the buccal tube, causing the pressure to be equally distributed. The intermaxillary Fig. 754. {Watso?i) elastics are adjusted with the lower appliance so as to preserve a proper balance only of the forces tending to cause a return of the distal occlu- sion, a very delicate elastic being finally used for the purpose. The retention of individual teeth is independent of this appliance. A modification of the appHance on the upper dental arch, described Fig. 755. (Watson) by Watson, consists of an arch wire, C, Fig. 754, so formed as to rest on the labial surfaces of the incisors, and passing between the cuspid and first bicuspid on each side, extends and is attached to the mesio-Hngual angle of the molar clamp band the screw of which is turned distally. Hooks for intermaxillary elastics are attached at the angle formed 842 ORTHODONTIA. by the arch wire bending lingually in the cuspid region. This form of arch wire serves to retain arch expansion in the bicuspid region, as well as the form of the anterior portion of the arch. The retention of the lower arch was also effected by means of a lingual wire attached to the molar clamp band and re-enforced an- teriorly by a lingual wire attached from cuspid to cuspid, as illustrated in Fig. 755^. The six lower anterior teeth are retained by banding the cuspids and uniting these bands with a lingual wire resting above the lingual ridge. A lingual arch is then bent to fit against the lingual surfaces of the bicuspids, resting against the cuspid bands and fitting closely under the ends of the wire attached to the cuspid bands and crossing the lingual surfaces of the incisors in close proximity to the gums. The distal ends of this lingual arch are attached to the mesio- lingual angle of the molar clamp bands with lingual screws pointing distally, and the hooks for intermaxillary elastics are soldered to the Fig. 756. buccal surface of these bands. The object of the appliance being thus made in two separate pieces is twofold: 1. The six anterior teeth, especially the cuspids, are more perfectly retained with a lingual wire from one cuspid band to the other than by a lingual arch attached to molar bands and resting against these six anterior teeth. 2. The teeth thus retained in sections have an opportunity to become self-supporting more rapidly than when all the teeth in one arch are bound together, as it were, by a lingual wire attached firmly to cuspid and molar bands. In the wearing of these appliances for retention of cases of Class II, Div. I, the intermaxillary elastics may be worn at night, and discarded after a time, leaving the buccal and lingual arches in position to retain the form and development of the dental arches for a still longer period. RETENTION. 843 In the simpler cases of mixed dentures of Class II, Div. i. in which there has been no appreciable change in the underbite, a mesio-distal retention only being necessary in addition to the retention of expanded upper and lower arches and corrected individual tooth malpositions, the author uses a modification of this method in that the upper expansion arch which was used for treatment is worn day and night during the first part of the retaining period, with intermaxillary elastics of de- creasing strength, then in the second part of the retaining period the upper expansion arch is worn with the most delicate elastics at night only, then alternate nights, and finally discarded. The expansion arches in these cases must closely fit the buccal tubes and be provided with friction nuts. The lower dental arch, when of regular form, needs but little reten- FiG. 757. tion for lateral development beyond that afforded by a single lingual arch attached to molar bands, having intermaxillary hooks soldered to their buccal surfaces. Occasionally, in more mature cases, the conditions of malocclusion will seem to demand the continued use of an upper lingual retaining arch, attached to cuspid and molar bands, and sometimes to incisor bands. In these cases, the buccal arch may be dispensed with and the inter- maxillary hooks soldered to the cuspid bands. In Fig. 756 is exhibited another method of application of intermax- illary force for the retention of the normal mesio-distal relations of a case of Class II, Division i after treatment which is occasionally used. An elastic is stretched from labial hooks upon upper cuspid bands to buccal hooks upon bands on the lower first molars. The retention of the expanded arches, as shown in Fig. 757, is provided for at the same time by the lingual wires attached to cuspid and molar bands. In the upper arch, D, the central incisors are 844 ORTHODONTIA. also attached to the h"ngual wire, the incisor bands having labial spurs extending over the lateral incisors, thus effectually preventing a return of the pointed arch w^hich v^as restored to normal shape during the treatment. The use of so many soldered bands is always an objectionable fea- ture of retention, because they give so little opportunity for the teeth to become self-supporting, and also because of the difficulties attending the re-cementation of the bands when one or more become loosened. When necessary to attach the lingual arch to incisor and cuspid bands, it is advisable to use lingual hooks bent over the arch as suggested by Lourie. Fig. 758. (Rogers.) Retention of Class II, Div. 1, Subdivision.— The intermaxillary retention of the subdivision of Class II, Div. i, in which the occlusion is normal on one lateral half and distal on the other, varies but little from the retention of the corrected bilateral distal occlusion, since it is neces- sary to wear a very light intermaxillary elastic on the normally related side in order to more perfectly balance the force of the elastic necessary on the side formerly in distal occlusion. Intermaxillary Retention in Class II after Change of Occlusal Plane. — (Abnormal Overbite.) In some of the cases of mixed dentures "of Class II, Div. i, in which the occlusal plane has been changed, the operative appliances shown in Fig. 557 are used for retention, the expan- sion arch being continued on the upper in connection with the use of the RETENTION. 845 bite plate, the lower arch being retained with a lingual arch wire. In these cases it is necessary to retain both a mesio-distal change in the dental arches as well as a change in the occlusal plane. Hence, the intermaxillary elastics should be adapted as in the treatment to exert a vertical as well as a horizontal pull affected by the triangular arrange- ment in Fig. 557. The elastics used should be decreased in strength during retention so that only the most delicate intermaxillary force is needed to balance the antagonizing resistance. This retention should be worn day and night during part of the period of retention, and nights only for another period, and finally discarded after the eruption of the bicuspids to occlusion if the length of time of retention and the develop- mental changes will warrant it. In some cases it is advisable to use the fixed inclined plane for reten- tion of these cases one form of which is shown in Fig. 752, a combination suggested by Rogers in which the triangular arrangement of the inter- maxillary elastics is used with the inclined plane for both treatment and Fig. 759. retention. A lower lingual arch is substituted for the expansion arch during retention. Fig. 759 illustrates an inclined plane of looped wire in connection with an apparatus similar to that shown in D, Fig. 757. The use of the wire loops, suggested by J. L. Young, makes a much lighter inclined plane that can be constructed any other way and the open spaces make it more easily cleaned. The distal tendency of the lower arch is counteracted by the inclined plane all of the time whether the intermaxillary elastics are worn or not, and in some cases this com- bination is advisable. Retention of Corrected Infra-occlusion of Bicuspids and Mo- lars in Class II, Div. 1 . — ^The occlusal planes of both upper and lower dental arches in some of the more mature cases require such extreme 846 ORTHODONTIA. changes that the tendencies to return to these abnormal planes requires retention by a continuation of the use of the operating buccal expansion arches as in Fig. 608 or the use of lingual arches antagonizing these reactive tendencies in a similar manner as shown in Fig. 748. Occasionally it is necessary, either after correction of the infra-occlu- sion of the lower bicuspids and molars or of a supra-occlusion of the lower incisors, to adopt this same form of retention of the lower dental arch. Retention of Class II, Div. 2. — ^The retention of Class II, Div. 2, differs from that of the first division of Class II in very few respects. The upper dental arch, however, presenting with a torsal or lingual tend- ency of the upper incisors, requires usually the use of the lingual retaining arch, with bands and spurs on the individual incisors to resist the tendency to rotate or return to positions of lingual inclination. Fig. 760. These cases usually possess a deep underbite, indicating infra-occlusion of the bicuspids and molars, and occasionally supra-occlusion of the incisors, and the retention of corrected occlusal planes in this division is the same as in that of the first division of Class II. The use of the spur and plane is well adapted for retention of the mesiodistal change in this division of Class 11. Occasionally, however, the continued use of intermaxillary force may be indicated. Retention of Class III. — ^The retention of a corrected mesio- distal change in Class III is usually much simpler than in Class II. In • early treated cases, where a sufficient overbite is obtained after treat- ment, considerable dependence may be placed upon the occlusal reten- tion of the incisors in normal occlusion. In early treated cases in which it is impossible to obtain much of an overbite of the incisors, an upper CONSTRUCTIVE TECHNIC. 847 lingual arch holding the upper incisors forward, attached to molar bands, with buccal spur and a lower buccal plane reversed from the relations, shown in Fig. 749 for Class II retention is advisable. In more mature cases of greater severity, as in Fig. 760, intermaxillary retention adjusted as in Fig. 761 from a lower expansion arch to hooks to upper molar bands attached to a lingual arch seems necessary. The chief consideration beyond that of the correction of mouth- breathing habits is the establishment of an overbite. In some cases it is necessary to discontinue treatment if an "open bite" condition is liable Fig. 761. to ensue on continued treatment with intermaxillary force, hence, in the use of this force for retention the occlusal relations of the upper and lower incisors must be carefully guarded. PART XIV. CONSTRUCTIVE TECHNIC. Necessity for Technical Instruction. — ^The necessity for tech- nical instruction in constructing appliances or parts of appliances adapted for the individual case is more evident at the present writing than at the time of publication of the first edition of this chapter in which the author stated that "the orthodontist of the future must be a constructive ortho- dontist." The ready made appliance needs as much reconstruction work upon it to adapt it to the dental arch, as if it were made entirely in the laboratory. The use of the plain bands on molars in preference to the clamp band for the majority of cases, the multiplicity of bands and tubes upon the anterior teeth, the soldering of telescoping pins and the 848 ORTHODONTIA. adjustment of expansion arches in the technic of the newer appliances for bodily movement, requires constructive ability of no mean order. Again, the field of retention, with its unlimited possibilities in the me- chanical construction of retaining appliances, requiring a combination of art and esthetics in the production of an efi&cient and inconspicuous apparatus, looms up before one with a demand for the most consum- mate skill in the art of construction. To the lover of the art of orthodontia, also, the various phases of constructive technic, in both the mechanical and esthetic features, present considerable scope for skill and originality. Materials for Construction of Appliances. — The first considera- tion in a material for the construction of appliances to be used in the mouth should be the selection of a metal or alloy that will be the least affected by the fluids of the mouth, and which in turn will least affect the surfaces of the teeth with which it comes into contact. Any orthodontic appliance in the mouth interferes more or less with the natural cleansing action upon tooth surfaces of the saliva, and of the tongue and cheeks in mastication, and to minimize this tendency, an appliance should not only be simple in design and application, but should be constructed of materials which will give the greatest im- munity from caries. Providing the quality of efficiency is not impaired by such a selec- tion of material, the choice of a metal or alloy for appliance construction is of paramount importance, the manner of its application and subse- quent adjustment being of lesser moment. So many different metals have been advocated in the past for the construction of appliances that it is necessary to point out from the standpoint of clinical experience those metals or alloys which are of the greatest advantage for use in the mouth, where physiological conditions must be taken into account. German silver was used to the exclusion of almost every other metal or alloy for many years in the United States, and for mechanical effi- ciency, except in the possession of the requisite tempers for the manufac- ture of expansion arches and bands, was almost an ideal material for the purpose. German silver, however, is acted upon by sulphuric, hydrochloric, and nitric acids; even a weak acid like acetic acid will attack it, form- ing a combination of the basic acetates of copper, which at least is not desirable. Pyrozone and iodine attack it vigorously. In the mouth German silver discolors and in a large number of cases corrodes upon the surface, sometimes to the extent of perforation CONSTRUCTWE TECHNIC. 849 of a molar anchor band. The pits formed by this corrosion become breeding places for bacteria, retaining a certain amount of the soft foods in their cup-like pockets. (Grieves.) Potassium sulfo-cyanate, which is normally present in the saliva, and which gives immunity to caries when present in sufficient quantity, badly discolors German silver. German silver will sometimes leave upon tooth surfaces, a metallic stain which is difficult to remove, unless careful prophylactic measures are taken during the treatment of a case. From a physiological standpoint, then, there is much to be desired in a combination of metals for appliances to be used in the mouth other than is possessed by the alloy of German silver. A material which will not discolor nor corrode, and which is not attacked by the fluids of the mouth, at the same time possessing the requisite temper for all the parts of an appliance, is much to be. preferred. The alloys of gold and platinum possess all these requisite qualifi- cations, and are made up in the form of band material and wire, possess- ing high degrees of temper and high fusing points. The alloys of gold and platinum will neither corrode, discolor, nor be affected by any acid or alkali, except aqua regia. The fusing point of platinum is 1775° Cent., of gold, 1075° Cent. An alloy composed of 90 per cent gold and 10 per cent platinum fuses at a temperature of 1130° Cent., which is very significant, proving that pure gold may be used as a solder upon this alloy without danger of fusing the latter, since the fusing point of the alloy is 55 degrees higher than the fusing point of gold. The points of chief importance in a gold alloy for appliance con- struction are that it shall contain sufficient platinum so that the fusing point will be so high that the ordinary blowpipe flame will not melt it while soldering and that it shall have the requisite temper. Gold alloys without platinum can be used, but invariably when sol- dered attachments are made to the arch in these alloys, if anything higher than i8k solder is used, the gold alloy is in danger of being melted. With platinum alloyed with the gold in proper proportion, soldered attachments may be made to an arch of the alloy with 22k solder and even pure gold. Soldiering Requirements. — ^The attainment of skiU in constructive technic in orthodontia lies chiefly in one's ability to perform difficult soldering operations in a rapid and efficient manner, involving a train- S4 850 ORTHODONTIA. ing of the eye as well as the hand in the building up of the units of a given appliance. The technic of the orthodontist is not up to date without every facility for easier and more rapid methods of soldering than are obtain- able by the investment of pieces to be united, or the approximation of parts by the use of bulky tweezers, and the use of the large flame of the Bunsen burner. The requirements for this class of soldering operations are as follows 1. A blowpipe flame of proper fineness and easily controllable. 2. Clean, bright surfaces on parts to be united, 3. Easy flowing solders, in convenient form for use. 4. A quickly acting flux in convenient form to apply. 5. Perfect approximation and fixation of parts to be united. The Blowpipe. — ^Taking up these re- quirements in order, the form of blowpipe should receive the first consideration. The necessities of the work require that a blow- pipe should not be more than a few inches in height, the burner to be upon a substan- tial base, and having attached to it easily adjustable valves for both gas and air, the tip of the burner being so constructed that a continuous fine, needle point flame of suffi- cient intensity may be obtained, and varied in size and intensity by valve control to suit the needs of the varying size and bulk of appliances to be soldered. A blowpipe which most perfectly answers these requirements, Fig. 762, is the invention of J. L. Young. The burner pillar is in sections, having a ball and socket at its lower end to enable it to be revolved in the base in any direction desired, and from a vertical to a horizontal posi- ion, a great advantage in soldering appliances. By turning a ring, and closing an air valve a Bunsen flame is secured. A compressed air outfit is most desirable in connection with a blow- pipe of this kind, as the ordinary bellows will not answer the purpose, the use of the foot in pumping moving the whole body enough to seri- ously disturb the soldering operations. Removal of Oxidation. — ^A clean, bright surface is always essen- tial to a successful attachment of solder, and oxidized surfaces should be carefully polished with a fine sandpaper disk in the engine be- fore soldering, or boiled in acid or alum solution and polished on the lathe. Fig. 762. CONSTRUCTIVE TECHNIC. 851 Solder. — While the higher carat gold solders in sheet form may be cut up to any requisite degree of fineness for marking the various sol- dered attachments (except for iridio-platinum and the attachments of pins and tubes for the sectional arch), the use of solder in the form of fine wires is far superior. These wire solders should be cut up in convenient lengths with a ring at one end as in Fig. 763 to distinguish them readily from platinum and gold alloyed wire. Fig. 763. With this form of solder, there is a great saving of time, as the end of the wire solder has only to be touched to the surface of one of the parts of an appliance to be attached, when a sufficient quantity will be fused in the required position. In the use of the other sheet form of solder, besides the number of motions required to pick up and place a small piece of it in position, it is continually slipping off from the appliance and lost, an annoyance not encountered with the wire solder. Fig. 764. Easy flowing gold solders in wire form are now obtainable at the depots, and in the use of the gold solders, for making attachments upon gold and platinum appliances, an intelligent use of the higher carats (22k) in the uniting of primary parts, with the consecutive use of a lower carat (i8k) for secondary attachments, will give assurance of the success of each soldering operation in their order, and if the degree of heat is Fig. 765. properly gauged, the union of a number of very small parts in close approximation may be much more safely accomplished than if but one grade of solder were used. It is possible, however, to become so adept that most of the soldering of gold and platinum appliances may be done with one grade of solder. In soldering iridio-platinum, pure gold must be used as a solder and it can also be used in wire form to advantage. 852 ORTHODONTIA. Fluxes. — Next in importance in soldering operations is the use of a flux which will quickly cleanse the oxidized surfaces so that the solder willxflow readily. Borax is the usual constituent of all fluxes for hard solders of either gold or silver, and when properly calcined and prepared for conv'enient use, will answer every purpose. A favorite method of Fig. 767 some operators is to have a specially prepared borax slate with various sizes of solder mixed with creamed borax on its surface, ready for imme CONSTRUCTIVE TECHNIC. 853 diate use. Considerable time is consumed in mixing the borax before every soldering operation in this manner, and the displacement of the solder from position when placed in the flame is an annoying and not infrequent occurrence. To overcome these difficulties, the author has combined a flux in a specially prepared wax soldering stick, of the sizie and shape shown in Fig. 764, and containing a calcined borax flux, which is not only instan- taneous in application, but by means of the wax body fixes cut pieces of Fig. 768. solder in position so that they cannot be displaced before fusion takes place. The only caution necessary in its use is that the surface to be soldered should be slightly warmed, and not heated to redness, before touching with the wax stick. -'i-o p!-. Borax fluxes incorporated in a vaseline base are also to be obtained in the depots and give very satisfactory results. A pair of solder t^veezers of the size and shape shown in Fig. 765, should be used for picking up pieces of solder, and its points should be kept clean and out of the soldering flame in order to be in proper con- dition to use. For cutting gold and platinum, iridio-platinum, and sheet solder, a pair of small shears with especially strong blades, such as is illustrated in Fig. 766, is especially adapted for use at the operating cabinet, being preferable to the larger laboratory shears for the purpose. Approximation of Parts to be Soldered. — ^A number of years ago, the author devised a set of delicate clamps, Fig. 767, for the approxima- tion of the various parts of bands and appliances while being united with solder, and the fifteen years of constant use and improvement have 854 ORTHODONTIA. brought them up to a standard of perfection which makes the operation of soldering extremely simple, accurate and rapid, as well as saving in time, patience, and nerves from the hand soldering method. There is hardly a single practical combination of appliance parts that cannot be perfectly adjusted in these clamps. Hand Soldering. — ^The hand soldering technic, in which parts of appliances are held in the fingers and adjusted by resting some of the fingers of one hand against those of the other, is a splendid manual training, and occasionally may be advantageously used in combination with mechanical methods of holding parts of appliances. Construction of Plain Bands for Incisors and Cuspids. — One of the most important adjuncts to the direct application of force to the upper and lower ten anterior teeth, is the plain band, or Magill band as it is often called after its originator. For use with the expansion arch, plain bands may be made of gold and platinum of .003 inch, thickness, and of an average width of .09 Fig. 770. inch. With the Angle sectional arch, the bands should be made of iridioplatinum .003 inch in thickness and of an average width of .19 inch, as this material can be used much thinner than the gold and platinum material, and will occupy correspondingly less space between incisors where all of them are banded. Gold and platinum band material is now furnished by the depots in strips of the form shown in Fig. 768 in any length desired. The band material should first be formed into a loop, the edges of which are forced between the mesial and distal approximating sur- faces of the tooth to be banded and the adjoining teeth, the free ends directed lingually or labially as desired, and after pulling the band material taut on the tooth, it should be removed and the proximal edges festooned so that they pass just beneath the labial and proximal gum margins. The ends of the loop should then be pinched together close to the tooth surface, as at A in Fig. 769. The ends of the band material should meet at right angles at the point of union, so as to form CONSTRUCTIVE TECHNIC. 855 a continuous inner surface of the band when soldered, asatB in the same cut. The author's band-forming ph'ers, shown in Fig. 770, are especially designed for this purpose, having concavo-convex beaks which accu- rately fit the surface of the teeth. Fig. 771 illustrates the nicety with which the concave edge of the beaks fits the labial surface of an upper incisor, when the pinch is made on the labial surface, and the accuracy with which the convex edge fits the lingual surface of a lower incisor. The plain band should be fitted closely to the tooth surface, for there will always be sufficient space for the cement for proper fixation of the band and protection of the tooth surface. The burnishing of the margins of the band may be done after it is in position and the cement still soft. Oftentimes, in forming the cuspid band, it is neces- sary to make an additional pinch at the mesial and distal angles, filling the pinched portion with solder and trim- ming off the projecting edge. Soldering the Band. — In uniting the ends of the plain band with solder, they should be held in a suitable tweezer, or in an automatic clamp as in Fig. 772, and having been fluxed, the band is held in the fine flame of the blowpipe, a piece of wire solder touching the edges of the joint until it is fused. The surplus ends are next cut off, and the ridge which remains polished smooth with the sand- paper disc, after which the band, if of gold and platinum, is trans- ferred to a boiling solution of acid or alum to deoxidize it, and then polished. If it is not to be cemented on at once, it should be properly indexed and filed until the next sitting. The iridio-platinum band material for use with the sectional arch should be roughened by drawing it over a round file No. 3 cut, leaving a surface to which the cement will better adhere. Also, in making the plain band of this material for use with the sectional arch, one edge of the iridio-platinum band should be trimmed to pass beneath the free margins of the gum, the edge presenting occlusally to be festooned so that it will be gingival to the contact points when in position which is of Fig. 771. 856 ORTHODONTIA especial importance when all of the incisor teeth are banded, economiz- ing the space of a double thickness of band material at the contact points. Accessories to the Plain Band.— As the plain band is usually utilized for the more direct attachment of ligatures, and for retaining appliances, as well as for lever tubes and traction screw tubes, the various methods of making these attachments should be carefully studied. Where the banded tooth does not need rotation, but simply a direct movement toward the arch, a notch in the seam of the band will prevent the ligature from slipping, as at A, Fig. 773. Fig. 772. Lingual spurs for rotation may be attached as at B, Fig. 773. The band should be held in a tweezer or a No. i clamp in the left hand, and a length of wire solder adjusted with the right hand to the point at which it is desired to attach the spur, and the parts to be united are held in the flame until the end of the wire solder fuses, when the band is quickly removed, the surplus solder cut off, and the spur finished. The retaining spur shown at D, Fig. 773, is attached as follows: a length of the retaining wire is held against the band with the right hand, the surface of the band having had a small piece of solder fused A B c D E F Fig. 773. upon it previously. The band itself is held in a tweezer or the No. i clamp. The lever tube, at C, Fig. 773, preferably square, is cut off the de- sired length and held in approximation with the surface of the band by the No. 3 clamp alone. Larger sized tubing for the ends of the traction screw, as at E and F, Fig. 773, may be adjusted to position with the Nos. 2 and 4 clamps^ as illustrated in Fig. 767. The short tubes may be held in the tip of the No. 4 clamp at any desired angle to the band while being soldered, being especially useful in the attachment of the tube at one corner of a cuspid band for the end of the traction screw. CONSTRUCTIVE TECHNIC. 857 Hooks and Spurs for the Expansion Arch. — For convenience in use, and saving of time at the chair, a number of pieces of iridio- platinum, and gold and platinum wire of two different sizes, i8 and 21 gauge, B. & S., about four or five inches long, should be kept in stock. Hooks may be easily made by bending a step in the end of one of these wires as shown in Fig. 774, the end soldered to the expansion arch in the desired position, and the surplus wire cut off. Spurs for the expansion arch should preferably be made of the iSk wire solder, <^r' '""""S- I attached similarly to the spurs on plain -^ bands. Fig 774. Construction of the Plain Anchor Band. — H. A. Baker has devised a valuable method of construction of the plain anchor band. The method is as follows: Upon a plaster cast of the teeth trim down the second bicuspid and second molar at an oblique angle from their occlusal surfaces to 1-32" or 1-16" below the gum line adjacent to the first molar which is to be used for the anchor tooth, as in Fig. 775. Continue the labial, lingual, and proximate surfaces of the molar Fig. 775. on vertical lines into the plaster cast beyond the gingivae, extending these surfaces to a level 1-32'' to 1-16" below the gum margins and preserving the contour of the tooth. Varnish the exposed portions of the tooth with shellac to obtain a hard surface. A plain band is then made to fit the first molar, soldering the joint upon the lingual surface and afterward burnishing the edges of the band into the grooves and depressions on the labio-occlusal and linguo-occlusal aspects of the tooth. The upper edge of the band should extend underneath 858 ORTHODONTIA. the gum a short distance. The band should next be fitted to the natural tooth, contouring in the gingival edge of the band enough so that the band will spring over the widest diameter of the crown of the molar. The first molar should be separated from the adjacent bicuspid and second molar so that the plain band will slip over the crown of the first molar freely, this separation being made during the interval between the first and second visits of the patient. The buccal tubes may be soldered upon the plain bands on the first molars and the expansion arch adjusted and aligned upon the Fig. 776. plaster cast, so that at the second sitting of the patient, the molar bands may be cemented in place and the expansion arch adjusted upon the natural teeth. The method described has many advantages, chief of which are the greatercomfort for the patient, and the expendi- ture of a minimum amount of time in fitting the appliance to the natural teeth. The author's method of making plain anchor bands is somewhat dififerent except in the general contouring necessary for the adapting of Fig. 777 the band to the anchor tooth. A number of convenient sizes of cylin- drical bands previously soldered are kept in stock, Fig, 776, ready for immediate use. These sizes for the average permanent molars are in length of band material as follows: 1.38 inches, 1.40 inches, 1.42 inches, 1.43 inches, 1.45 inches, 1.47 inches, 1.50 inches, 1.52 inches, 1.55 inches. The ends of these sections of band material are first beveled oppositely with a file, the band material formed into a cylinder with the bevels lapping. The ends are soldered with i8k solder, or with 24k gold, the latter making the union soft and pliable. CONSTRUCTIVE TECHNIC. 859 A band is selected which will fit tightly when slipped over the crown of the molar past the contact points. It is then removed and the oc- clusal edge contoured inward all around, when it is replaced on the molar and adapted to the grooves and cusps with the instrument illustrated in Fig. 582. The band is removed once more and the buccal and Fig. 778. lingual edges which present gingivally also contoured, so that it will cling tightly to the tooth on these edges, when it is ready for attach- ing the buccal tubes, lingual wires, etc. Assembling the Parts of the Anchor Clamp Band.— The molar clamp band is made up of a short piece of band material, and a lingual Fig. 779. screw passing through a short tube soldered at one end of the band, adjusted with a nut turned upon the lingual screw. For the construction of the clamp band, the author P has invented a set of five special clamps which enable I the operator to quickly assemble and solder the several I parts of the clamp band. For adjusting and soldering the band and the lingual screw, the author makes use of No. 6 special clamp, which holds the two parts in adaptation during the soldering operations, as shown in Fig. 777. The solder and flux are always placed between the parts to be united before placing in the flame. The short tube is held in apposition a short distance from the other end of the band with a No. 7 clamp of the set shown in Fig. 778. In case the lapping end is not desired, the short tube is held on the extreme end of the band with clamp No. 8, shown in Fig. 779. 86o ORTHODONTIA. The band is then formed in a circle, the screw thrust through the lingual tube and the nut adjusted to it, when it is ready for the attach- ment of the buccal tube. Soldering Buccal Tube on the Anchor Clamp Band. — ^This oper- ation is one that is frequently done and requires so much exactness that the aid of special clamps is almost indispensable to facilitate rapid and correct soldering of these parts. Almost two-thirds of the molar bands purchased at the depots have to be subjected to a change in the position of the tube so as to secure proper alignment of the arch wire as in Fig. 780. During the treatment of Class II and III cases, the tipping of the anchor teeth distally and mesially requires a re-alignment of the an- chor tubes occasionally to keep up the efficiency of the anchorage. rN. a--' \ ; y i r\ ■1/ HB BBSntBWnCBB iA Fig. 7S0. To prevent the expansion arch from dropping below the edges of the incisors, as at A, Fig. 780, in a Class II case, the anchor clamp-bands should be removed and the buccal tubes realigned so that the expan- sion arch will rest upon the surfaces of the incisors as at B, Fig. 780. The technic of this operation is as follows: The molar clamp band is held in a vice-like grip in the dog jaw of special clamp No. 9 (Fig. 781) which is attached to the distal part of the clamp band so as to enable this clamp to be held in the fingers of the left hand, while those of the right control clamp No. 10, which engages the buccal tube, with the mesial end toward the handle of the clamp. Having previously attached a piece of solder on the buccal side of the surface with the wax flux, at the point at which the tube is to be CONSTRUCTIVE TECHNIC. 86i joined, the right angle arm of the No. 9 clamp is placed on the lingual side of the band, and the arm holding tube is allowed to drop down into position on the buccal surface of the band. The tube is aligned horizontally with the edge of the band, and then the clamp band and tube are held in the flame of blowpipe until the solder is perfectly fused. Construction of Complicated Retaining Appliances. — It has been the custom of many operators to make, at the chair, retaining appliances soldered to a lingual wire, fitting the lingual wire from one band to the next, solder- ing and fitting to place, with the possibility of inaccuracy and failure of the appliance to do the work for which it was intended. The author has given up this method of attaching the bands to the lingual wire, preferring in every case to make and fit the bands to the teeth and solder the lingual wire to the bands upon a plaster cast, obtained from a plaster or modelling compound impression of the teeth with the bands in position. The bands are replaced in the impression and the cast poured, the bands ap- pearing upon the teeth of the plaster cast when the im- pression material has been removed. Laboratory Soldering Stand. — ^A reversible blow- pipe. Fig. 782, attached to a soldering stand has been made up, at the suggestion of the author, for laboratory use in cases where appliances are soldered upon plaster casts. By means of the swivel joints of the blowpipe, the flame may be directed upon any portion of the inside circum- ference of the soldering block, and fixed at any desired position. The position of the blowpipe is under such per- fect control that the direction of the flame may be changed from left to right, up or down, on or away from the ap- pliance by a slight pressure on the handle. Soldering Technic of the Angle Sectional Arch. — The constructive technic of the new Angle sectional arch requires more delicacy of manipulation, especially in solder- ing, than the assembling of the parts for use with the plain expansion arch and its anchor bands and auxiliary lingual wires, etc. Hand soldering, although still effective for the uniting of the parts of the new appliance, has given place largely to methods whereby the smaller and more delicate parts to be united, Fig. 781. 862 ORTHODONTIA. such as the vertical tubes to the plain bands and the upright locking pins on the middle arch sections, are held in a specially constructed jig or an automatic clamp of special design. One method (Angle) of solder- ing the vertical tube to the plain band is to place a staple of solder, Fig. 783 {i8k for gold and platinum and 24k gold for iridio-platinum bands) upon the mark on the labial surface of the band, lay the tube upon it, and hold the band in the flame of the blow^pipe v^^ith a solder tweezer until the staple fuses. Another method, suggested by the author, is to use an automatic clamp, Fig. 784, for holding the vertical tube in position in addition to the staple solder. The upper arm of the clamp has inserted into it a short section of stub steel wire, tapered at one end to receive and tightly hold the vertical tube so that it cannot be lost or dis- placed during soldering. A still more delicate soldering operation is that of uniting the arch pins to the middle section at the indi- cated points and at the proper angles of inclination for each tooth. The hand soldering technic described by Angle consists in the use of a pin Fig. 782. Fig. 783. Fig. 784. holder (Fig. 785) which is held in one hand and the arch wire sup- ported in the other by a pin vise which will be found of assistance in holding the arch wire firmly. Fig. 785. Owing to the difficulty of placing a piece of solder between the pin and the arch, the use of solder rings has displaced other methods of manipulation. One of these rings. Fig. 786, is sprung on the fish-tail end of the pin, the head end being in the pin-holder, and the pin and arch CONSTRUCTIVE TECHNIC. 863 wire held in approximation, the pin at the properly judged angle of inclination to perfectly fit the tube, and the solder fused into pla( e. To still further prevent inaccuracy in the alignment of the pin paral- lel with the tube that is to receive it, and to get the exact angle of inclina- tion, the soldering jig (Fig. 787 A, B, C), was invented by Angle, assisted by Gough and Lane. The arch wire, resting passively in position in the mouth, is firmly held in the vise A at a point not more as B Fig. 786. Fig. 787 than a half inch away from the point at which the pin is to be sol- dered, the copper wire B is clamped into a hole near the top of the vise with a set screw, and the other end of the wire bent so that it rests against the point the head of the pin will occupy when in place. The proper inclination is given by bending the copper wire. On removing the jig, still fastened to the arch wire, from the mouth, the pin carrier, C .holding the arch pin with hook pointing labially and a ring of solder Fig. 788. in place, is telescoped over the end of the copper rod in exact register for the pin to be soldered to the middle section when adjusted. Another method of soldering these delicate arch pins in place is the use of a delicate compound clamp (Fig. 788) devised by the author. The arch is inserted in a hole of the same diameter in the upper arm of the clamp, where it is held by friction. The middle arch section is slipped into an extra spring arm on the lower part of the clamp, where it is securely held, while the pin is adjusted to the notch in the arch wire at the properly judged angle of inclination, and soldered. If the angle of inclination is incorrect after trial in the mouth it is easily corrected on readjustment of the arch wire in the clamp by slightly rotating the clamp on the arch wire while the solder is fused at the base of the pin. 864 ORTHODONTIA PART XV. PLASTER TECHNIC. Necessity for Accurate Models. — The primary importance of ■diagnosis in the consideration of the possibilities of treatment of malocclusion, renders it necessary that accurate models of the teeth and dental arches should be made of every case so that a foreknowledge of every condition of malocclusion and of every special pathological indi- cation may be gained by a careful study of such models. The charts of Dr. Hawley for arch predetermination, and the sym- metroscope of Dr. Griinberg were both designed for use with plaster casts which accurately reproduce the dental arches, and the measure- ments taken and conclusions drawn from these methods of diagnosis would otherwise have no definite value. Readings from Casts. — ^The casts of each dental arch in occlusion should represent, to the minutest degree, the exact variation of the occlusion from the normal, the depth of cusps and length of overbite the compensating curves. Separately they should exhibit all the fine lines of the anatomical structures which it is intended they should copy, such as the rugae and stipples of the gum tissue, the form and attachment of the frenum labium, the height and width of the palate, abscess fistulas, and pathological conditions such as hypertrophy of the gingivae, the degree of development of the arch well up to the line of demarcation of the cheek and gum tissue, and especially the perfection or imper- fection of every tooth surface, including developmental grooves and inclined planes, and the facets of the cusps, which latter, to the ex- perienced eye, tell a story which can be learned in no other way, of the articular movements of the mandible. Reference to the model during the treatment of a case is of value in indicating the changes in growth of the dental arches, since it exhibits the exact degree of arrested or deficient development at the beginning of treatment, and comparative measurements taken occa- sionally will record the progress in a given case. PLASTER TECHNIC. 86s The model also indicates the proper relations of retaining appli- ances upon completion of the treatment. A collection of finely made models serves not only as a library of reference and study, but also as an accurate indication of the individual skill of the operator, both in the making of the models themselves, and in the perfection of treatment which they exhibit. Medico-legally, the plaster reproduction of the teeth in the model is an accurate record of fact, which is accepted as evidence in a court Fig. 789. of law, thereby ensuring some protection to the operator from the unappreciative and dishonest who resort to questionable methods in the evasion of their just obligations. Impression Materials and Methods. — ^Plaster-of-Paris has long been recognized as the ideal material for taking accurate impressions of the teeth, casts from which are absolutely accurate in detail of re- production, as in its use in surgery, its reproduction of internal or external structural anatomy having not been superseded by any other material. 55 866 ORTHODONTIA. Angle was the first to place model making in the list of the arts by the introduction of a method, which in its main char- acteristic, is still followed, the improvement in technic and detail which have been suggested by others in the same field being here described. As the impression in plaster will reproduce the finest lines of tooth surfaces, care should be taken that all hard and soft deposits be removed, and the teeth thoroughly cleaned before the impression is taken. The Impression Tray. — The Angle impression trays, illustrated in Fig. 789, are especially adapted for taking full impressions of either arch, having high rims, and being so shaped and polished that they may be removed soon after insertion in the mouth by a slight manip- ulation, leaving the setting plaster in the mouth to be sectioned, frac- tured, and removed in several pieces. ; ^ Trays should be selected according to the size of the mouth, large enough to allow for at least one-eighth of an inch of plaster between the teeth and the sides of the tray, which will admit of a slight bending for such adaptation. Fig. 790. These trays are provided in graded sizes 21, 21^, 22, 22^, 23, and 23^ in the upper set, and in corresponding sizes 24 ,25, 26, and 27 in the lower set. The surfaces of the impression trays should never be scratched nor indented, as any marring of the surface prevents easy removal of the tray from the impression in the mouth. It will be found an economy of time to replace slightly marred trays with new ones. Mixing of the Plaster.— On account of the quick setting of im- pression plaster, the use of salt or potash for hastening this process is unnecessary in the plaster mix, in fact, they are detrimental to the securing of a perfect impression because of the haste necessary in manipulation, and the coarseness of crystallization of the plaster, which is destructive of the fine lines on the surface of the impression. Distilled water at a temperature of about 70° F. is preferred for comfort and for perfect mixture of the plaster. The quantity of water necessary for the usual mix should be some- I PLASTER TECHNIC. 867 what accurately gauged, and the plaster gradually sifted in until it absorbs the water completely, when it is ready for immediate pouring into the tray which has been selected of a litde larger size than the dental arch of which an impression is desired. Only the best impression plaster should be used, French's plaster as furnished by the depots in a metallic can with tightly fitting cover being preferable, as it may be kept perfectly clean and dry in this receptacle. Distribution of Plaster in the Tray.— If the impression is to be of an upper arch, the palatal portion of the tray should not be covered with the plaster, the rest of the tray being about three quarters filled. Fig. 791. — (Rogers.) and a small surplus allowed to rest upon the handle to be forced under the lips. If necessary, the buccal and labial spaces may be first filled, using a bone or glass spatula to carry the plaster to place, as suggested by Rogers. The tray is then inserted in the mouth, and pressed quickly into position, taking care that the teeth are about equally distant from either side and the bottom of the tray. While being held in position with the middle finger of the left hand, the surplus plaster may be cleaned from the tray with the tweezers and cotton. The impression should be allowed to harden until it will fracture properly, when the tray should be renoved by exerting a slight and uniform downward pressure upon the handle, after which surplus pieces may be removed from the mouth with the tweezers and cotton. 868 ORTHODONTIA. The impression should next be grooved vertically, on both sides usually over the cuspid region, with a form of knife shown in Fig. 790, which is best adapted for reversal in grooving both upper and lower impressions without danger of cutting the lips, the short curved blade being admirably shaped for skillful manipulation. By prying from the bottom of one of the grooves with this same knife, after the plaster is hard, the central section of the impression may be removed easily, and the two buccal portions by exerting an outward prying motion with the thumb against the anterior edge, leaving the palatal portion to be gently pried out with an instrument. Fig. 792. — (Rogers.) The pieces are then placed in a small box upon which is marked the name, date, and age to be copied later on the index record of the patient. The lower impression differs from the upper only in the detail of the manipulation of the tray, care being taken not to allow of an excess of plaster in the distal ends of the grooves. Figs. 791 and 792 represent very perfect lower and upper impressions of the teeth after the fractured pieces have been assembled. Assembling the Impression. — The fractured pieces should be thoroughly dried, over night usually, although they may be quickly dried by placing them upon a piece of tin over a burner, and then assembled, beginning with the larger 'pieces, adding one at a time, and dropping a small bead of hard sticky wax upon the outside of the impression at intervals of about one-quarter of an inch along the lines J PLASTER TECHNIC, 869 of fracture, as illustrated in Fig. 793. The edges of the fractured portions should be cleaned of crumbled pieces before uniting them. Occasionally, it will be of advantage to replace broken pieces in the tray, but, as a rule, better results are obtained without doing so. Varnishing the Impression. — After being properly assembled, the impression should be varnished with a solution of shellac allowed to dry for half an hour, and then varnished with a solution of sandarac, repeating the last varnish again in another half hour. These solutions are so thin that they leave a scarcely perceptible coating upon the surface of the impression, although rendering it easily separated from the cast, the shellac giving a color line to cut to, and filling the pores, and the san- darac simply filling over the surfaces of the pores, so that capillary attrac- tion cannot take place when the impression is filled.* Fig. 793. Filling of the Impression. — The varnishes being thoroughly dried, the impression may be placed in a basin of clean water to become infiltrated from the outside with water, while the plaster is being mixed ready for its pouring. A slow setting model plaster is preferred for a hard cast, although many have used the impression plaster with good results, its fineness giving a very beautiful surface. The plaster should be mixed in the same manner as for the impres- sion, and a small portion placed in the heel of the impression and carefully worked forward from one tooth cusp to another with the ♦According to Angle, these solutions should be prepared in the proportions of i ounce of shellac to 3J ounces of alcohol, for the shellac varnish and i ounce of sandarac to 2^ ounces of alcohol for the sandarac varnish. SjO ORTHODONTIA. camel's hair brush, until all the cusps are perfectly filled, when the remainder of the impression may be quickly filled with the plaster knife, which should be of platinoid so as to prevent rusting. A portion of plaster should be placed upon a clean glass slab and the impression inverted thereupon, and pressed down so that the anterior Fig. 794. edge is within one-half inch of the glass surface, preserving a parallel between the bottom of the impression, or tray, if present, and the hori- zontal line of the glass slab, as in Fig. 794. The surplus plaster is then trimmed away with the plaster spatula, and the plaster allowed to harden for about twenty minutes before it is ready to be again touched. Fig. 795. Sectioning and Removal of Impression. — The impression is more easily removed from the cast within half an hour from the time of its filling, as it then contains the greatest amount of moisture. However, it should be immersed in water again for a few seconds to still further soften the surface before attempting to separate the im- pression from the cast. PLASTER TECHNIC. 871 The small beads of wax should be cut o£F and the portion of the cast extending above the impression roughly trimmed with the cast trimmer, shown in Fig. 798, to approximately the shape to which it is intended to conform when finished. The sides of the impression may then be vertically and horizontally Fig. 796. grooved as in Fig. 775 using ihe smaller knife shown in Fig. 796, a method suggested by Rogers. The depth of the grooves should not be greater than the brown color of the shellac varnish, which appears as the bottom of the groove approaches the surface of the cast. Fig. 797. Beginning at the heel of the impression, one section at a time is pried away with the grooving knife, removing the upper sections first. The author prefers to shave down the surface above the occlusal edges of the teeth until the brown color above the prominent tooth cusps begins to appear before making the vertical and horizontal 872 ORTHODONTIA. grooves in most cases, and many times a single vertical groove in the region of the cuspid on each side is sufficient for the easy removal of the sections extending from these grooves to the heel of the impression. The front of the impression should always be horizontally grooved to prevent accidental injury to the incisors in removal. Oftentimes, the lines of fracture, which may run along the cusp surfaces of the teeth, will facilitate the removal of the impression very materially. It will almost always be found necessary to groove the lingual surface of the impression upon a lower cast before it is possible to remove it. In an upper impression also, it will often be necessary to make a groove lengthwise of the palatal section of the impression and then remove one-half of the palatal portion at a time. It is well to mark on the surface of an impression, before pouring, the positions of teeth in labial or lingual occlusion, to prevent marring them in the sectioning process. Trimming of the Model.— After the removal of the casts from the impressions, they should be moistened in clean water, and then roughly trimmed to the geometrical outlines which have been accepted as most artistic and harmonious for each, the base for the lower cast being trimmed to the inside pattern in Fig. 797 with slightly rounded front, and the up- FiG. ^^?,.-{Eastman Kodak Co.) P^r cast to the outside pattern of this figure, being precisely similar to the upper outline, except for the pointed front, which not only affords extension for a frenum labium of varying size, but gives a pleasing and distinctive variation to the capital of the model. From a geometrical standpoint, the two patterns present the forms of two triangles with equiangular basal angles which have been clipped by lines parallel to the lateral lines of the triangle from one-quarter to one-half an inch in length, and the anterior angle cut across from inter- sections directly over the cuspids on the lateral dimensions by the curve on the lower cast and the obtuse angle on upper cast. Constructed upon these lines, the base and capital present almost similarly formed designs, with the long sides of the triangles parallel to the buccal surfaces of the bicuspids and molars, and the median line of the anterior sections equidistant from the cuspids except where there is much divergence of the anterior teeth mesially or distally, when the median line of the capital may be made to coincide with the central line of the cast as indicated by the rugae. PLASTER TECHNIC. 873 This rough trimming may be done with great accuracy and little effort by cutting the vertical and horizontal planes with a cast trimmer, designed like the print trimmer shown in Fig. 798, but modified for plaster work by being provided with a brass covered base and a high beveled removable steel blade, which is kept sharpened to the edge of a fine chisel. Fig. 799. — S B, shooting board. P, plane. ^ The vertical planes on the lower cast should be cut first to within a quarter of an inch of the perfected pattern, and then the base of the cast trimmed so that it is parallel to the plane of occlusion. In cases in which the compensating curves are very marked, the plane of occlusion might be represented by the plane passing through Fig. 800. — {Rogers.) or touching the tips of the distal cusps of corresponding molars on either side and the edges of the central incisors. The vertical planes are next corrected and finished to almost the exact final pattern, the finishing touches, however, being reserved for the plaster plane. 874 ORTHODONTIA. Northcroft has invented an accurate, labor saving plaster plane which runs on a shooting board provided with an adjustable angle piece, with which to accurately produce the several vertical planes on the case (see Fig. 799). A step is also a convenient part of the shooting board, Fig. 801. since it facilitates the cutting of the anterior planes without danger of injury to the incisors. The author prefers the steel blade to one of phosphor-bronze as the former retains its keen edge for a much longer itme than the blade of a rust proof alloy which has no advantage exceut its freedom from rusting. Fig. 802. The thickness of the mechanically finished portion of the cast is determined somewhat by the size of the anatomical portion, but should seldom, in a cast of the permanent teeth, be less than one-quarter of an inch in the height of the anterior vertical planes. PLASTER TECHNIC. 875 After the lower cast is properly aligned and finished to form the base of the model, the upper case is cut to approximate the inside pat- tern shown in Fig. 797, and is then placed in occlusion with the base so that all surfaces and angles of the capital may harmonize with those oi the base. The upper surface of the capital should then be planed down until it is parallel with the horizontal, unless it is too thin, in which case the required thickness may be secured by inversion of the occluded model, capital downward, upon a small quantity of fresh plaster upon a glass slab, it being necessary to manipulate the inverted occluded casts so that the base of the model will be in the horizontal plane as judged by the eye. The planes of the sides of the capital should be all vertical planes, and the posterior vertical planes should coincide, if possible, giving Fig. S03. an accurate guide to the occlusion if it should not have been marked on the cusps, as shown in Fig. 800. A slight bevel cut around the entire edge of both capital and base adds to the artistic finish, and preserves the model from chipping of otherwise sharp angles in handling. The mechanically finished surfaces of the model may be made still smoother by finishing with a fine broad, flat, jeweler's file after the casts are perfectly dry. The trimming of the capital and base according to certain definite geometrical lines, is not only the most artistic and best proportioned conformation of otherwise ungainly reproductions, but it serves the very practical purpose of a standard for uniformity which enables 876 ORTHODONTIA. the busy orthodontist to more quickly and consecutively follow out the definite rules for obtaining esthetic effects than by the old and less accurate methods of model trimming. The anatomical portions of the model should represent perfectly the parts which they are intended to reproduce, and will be perfect in proportionate degree to the care which has been taken in the consecutive steps of their production. Marking and Numbering of Models. — When such infinite pains have been taken and artistic skill used in securing a beautiful and har- moniously proportioned model, it should not be ruined by marking the name of the patient, the age and the date of commencement of treatment upon every surface of the mechanical portion, as is often done. Each model needs its serial number for the cabinet, which may be Fig. 804. stamped with India ink upon the labial surface of the base ofthe model and the posterior surface of the capital, leaving all other surface of the model void of any marks whatever. In numbering, it is advisable to keep the same serial number for the before treatment and after-treatment models, distinguishing consecu- tively made models by progressive alphabetical lettering such as 105a, 1056, 105c, etc. Repairing Defects. — If a good impression has been first secured and the detail of assembling of the fractured portions, the varnishing, pouring and removal of the cast, carried out according to the instruc- tions previously given, very little, if any, retouching will be necessary upon the anatomical portion of the cast. PLASTER TECHNIC. 877 But, at least, the amateur is liable to get a few air bubbles or other imperfections upon the surface of some of his casts, which will need some little skill in the use of the camel's hair brush to render them un- noticeable. Air bubbles and other indentations such as are often caused by the knife blade in separating, are filled with plaster in the following manner: first, moisten the cast or the portion of it needing repair, then with the camel's hair brush carry a small quantity of very thinly mixed plaster into the bottom of the air bubble, repeating until it is a little more than full, when the correct contour is obtained by a twisting, wiping motion of the slightly moistened brush over the surface. Fig. 801 represents an upper cast which has a considerable number of air bubbles caused by carelessness in pouring the impression, and the loss of contour of some of the cusps of the teeth makes the cast rather unsightly. A little practice with the brush and plaster will en- FiG. 805. able the operator to restore the contour as in Fig. 796, which illustrates the same cast as in the previous figure after it has been treated by this method. Fractured teeth and cusps are somewhat differently treated, since it is almost impossible to force plaster of any consistency into a crack such as is visible on adjusting two fractured portions of a tooth together. One of the surfaces of the fracture should be carved out to a cres- cent shape, not touching the periphery of the cusp or tooth, however, as this will be needed to place it in register, after which the groove thus made may be filled with thin plaster in the same manner as the air bubbles. This method of uniting fractured pieces is very artistic in effect and the result permanent, being preferred to cement which causes a line of demarcation which is especially noticeable in a photograph. Fig. 803 represents a badly fractured cast, the right cuspid, both centrals, and the left lateral having been accidentally broken off. Fig. 804 exhibits the same cast after the fractured pieces have been reunited by this method. The right central was restored in contour entirely with the brush, since the fractured portion was lost. It is possible to restore even such a delicate part as the frenum labium, 878 ORTHODONTIA. which seldom escapes fracturing in separating, but a knowledge of the minute anatomy of the parts is essential to the attainment of artistic and esthetic results in attempting the reproduction of lost portions of the anatomical part of the cast. The lines of fracture of the impression are reproduced in the cast, and should be carefully burnished down with the spoon blade of a wax spatula adapted for the purpose, such as is illustrated in Fig. 805, being an S. S, White No. 7 double bladcd spatula. The smaller blade may be sharpened upon one edge to be used in removing any superfluous plaster contiguous to the festoons of the gums on the cast, also in carving out any surplus plaster from the embrasures of adjoining teeth, and the cusps of bicuspids or molars which are im- perfect. Any attempt at carving beyond the shaving of superfluous plaster, quickly shows its artificiality and should be avoided. PART XVI. PROPHYLAXIS. Mouth Hygiene. — During the wearing of appliances in the mouth the greater liability of food collecting around the teeth, and the lessened activity of the oral fluids in performing their natural cleansing function makes it imperative that especial prophylactic measures be instituted. The patient's teeth should be thoroughly cleaned before the com- mencement of operations, and during treatment instructions should be given for the frequent use of the tooth brush, preferably after each meal and upon arising. A tooth brush with one row of bristles is much better adapted to cleansing above and below the expansion arch than the brush with several rows of bristles. Frequently, the removable parts of the appliance should be removed, and the teeth cleansed carefully with pumice or washed with alcohol. It is of still greater benefit to have the patient referred back to the family dentist for more detailed prophylactic treatment, especially with the orange wood stick and pumice. Care of Ligatures. — Silk ligatures should be frequently renewed as they readily absorb the food products and become active agents in the formation of "retention centers." If silk Hgatures are saturated in campho-phenique, and kept tightly sealed in glass tube containers, they will remain free from the products of food decomposition for a much longer period. PROPHYLAXIS. 879 Pneumatic Sprays. — The compressed air spray in connection with antiseptic mouth washes, is most beneficial as a prophylactic measure, being used at each visit of the patient throughout the treatment. Ferris has recommended a combination of sprays which have certain peculiar reactions which make them of exceptional value, being both chemical and mechanical in their action. The first of the series of sprays contains the active agent iodine in combination with potassium iodide, which acts germicidally to de- stroy the spores and parent cells in albuminous material, which it read- ily penetrates, staining the bacterial plaques so that they are visible upon tooth surfaces. The second spray consists of a starch solution which absorbs the stained plaques, forming a flocculent precipitate, which is readily removed by the third spray which is a simple solution of sodium car- bonate, having the power to decolorize the precipitate previously formed, at the same time freeing the surfaces of the teeth still further by saponifying the fats. The antiseptic and beneficial value of these sprays, used consecu- tively, is not excelled by any other at present known methods of oral an- tisepsis. The series of sprays are given below in the order of their use, it being necessary to have separate nozzles for each spray, which also must be used at the temperature noted in order to have the desired efifect. I. I^ — lodini, gr, xxx. Potassii iodidi, gr. xix Aquae dest. ad. q. s. 5 iv. Sig. — To be used in spray under high pressure at the temperature of 98° F. II. I^ — Starch, gr. xxxviii Aquae menth. pip. 5 iv. Oleum menth. pip. rr\ xx. — M. Sig. — To be used at the temperature of 115° F. In makin ■ this compound, mix the first two ingredients and let stand for five minutes, then boil for five minutes, then add the flavoring. III. I^ — Sodii carb., gr. xxxviii. Aquae gaultheria, 5 iv. Olei gaultheria, n\ xxx. — M. Sig. — To be used at the temperature of 115° F, 88o ORTHODONTIA. Tonic Mouth Wash. — Ferris also recommends a tonic mouth wash to give tone to the mucous tissues, and to develop normal secretion during abnormal conditions. The formula is as follows: — Formula No. IV. I^ — Hydronaphthol, Menthol, aa gr. xxx. Oil gaultheria, Oil cassia, aa n^ iv. Alcohol, 5 X. Tinct. capsicum, 3 i Aquae dest., ad q. s. 5 xx. M. Sig. — Teaspoonful to half-glass hot water five times dail INDEX. Guide to the Index. — The index has been arranged with a view to direct the reader to his subject without delay. All readers do not think of the same subject matter in the same form, therefore the same subject will be found indexed in various forms. For instance: "Preparation of cavities:" "for fillings, i6i" "Cavities:" "preparation of, for fillings, i6i" "Fillings, preparation of cavities for, i6i" Where a — appears before a line it indicates that the indexed line relates to the sub-heading above it. Abnormal arch development, 631 frenum labium, 649 operation for, 763 Abscess, acute alveolar, 360 chonic alveolar, 362 pericemental, 370 pocket, secondary, 369 with sinus, 364 without sinus, 363 Absorbed root, 368 Absorbents, the use of, 161 Accessories to the plain band, 856 Adaptation of the arch, 699 Adenoids, 64J Adjusting the arch wire and pins. 731 the rubber dam, 152 Adjustment of anchor clamp bands, 706 Adventitious growths, removal of, 643 After-pains of extraction, 454 After-treatment of extraction, 455 Alveolar hemorrhage from the extraction of a tooth, 452 Amalgam, 244 Amalgam and cement, 256 Analgesics, 226 Anatomy of the human teeth, i Anatomical parts of the teeth, 2 Anchorage, 679 anterio-posterio re-enforcement of anchorage, 686 conservation of, 693 first molar, 680 fixed appliances, 693 intermaxillary, 687 uses of. 689 mechanical requirements of, 681 occipital, 689 simple, 683 stationary, 683 summary of principles, 695 Anchor clamp bands, adjustment of, 705, 706, 708 teeth, bodily control of, 669 tubes, alignment of, bucco-lingual, 707 Anesthesia, local, 393 56 88x Anesthetization and devitalization of pulps, 32s for removal of pulps, 326 Anesthetizing the pulp, method of, 415 Angle of the tooth, 2 Angle's classification, 651 Anodynes, 226 Antagonizing spurs, 838 Anterior and posterior arch retention, 832 Antrum, 369 Apex, 2 Apical foramen, 2 Application of principles, 696 of the Roentgen ray to dentistry, 541 Appliances : choice of metals for (orthodontia), 848 efficiency of (orthodontia), 692 materials for construction of (ortho- dontia), 848 Approximation of parts to be soldered, 853 Arch: expansion, 696 — divided, 698 — threadless, 698 — variety in form, 697 integrity preservative forces of, 613 predetermination, 657 retainer, lingual, 833 Arches: Case reciprocating, 691 malrelation of. 651 of temporary teeth, 605 Area of den to-facial inharmony, 618 Arrangement of light in the operating room, 85 Arrested developmental conditions in the arches, early treatment of, 735 Arsenical poisoning, 340 Articulation, 613 Artificial roots, 484 Asepsis in the operating room, 89 Assembling the impression (orthodontia), 868 parts of molar clamp band (ortho- dontia), 859 882 INDEX Assistants in the office, 526 Associated anatomical structures, devel- opment of, 615 Auxiliary lock pins, 733 Badly decayed root, 359 Band: accessories to the plain, 856 assembling parts of anchor clamp, 859 construction of the plain anchor, 857 Magill, 854 removing plier, 709 soldering the, 855 Bands, plain, 854 Beauty, physical relations of, 617 Bending of loops, 731 Bibs, 160 Bicuspids: lower first, 27 — buccal surface, 27 — cervical margin, 29 — distal surface, 29 — lingual surface, 27 — mesial surface, 29 — occlusal surface, 27 — pulp cavity, 30 — root, 30 second, 30 upper first, 19 — buccal cusp, 19 — buccal surface, 20 — cervical margin, 23 — distal surface, 22 — lingual surface, 21 — mesial surface, 22 — occlusal surface, 19 — pulp cavity, 23 — root, 23 second, 24 Bilateral expansion of the dental arch, 718 infra-occlusion of bicuspids and molars, 656 Blood-vessels of the pulp, 83 Blowpipe, the Young, 850 Bodily control of anchor teeth, 669 Bon will's diagram, 658 Bromids, 226 Buccal cavities, 272 Buccal tubes on anchor clamp band, 860 Bucco lingual alignment of anchor tubes, 700 Burs, 185 Cabinet, the dental, 91 Calculus, 109 Capping the pulp, 320 Card system, 532 Caries, pathology of dental, 119 Case reciprocating arches, 691 Casualties attending tooth extraction, 451 Causes and treatment of dbcolorations of teeth, 375 Cavities : division of, 168 examination of teeth for discovery of, 131 fissure, 170 Cavities: instruments for preparation of, 182 management of large proximo-occlu- sal in pulpless bicuspids, 217 large, in pulpless molars, 217 nomenclature, 165 of internal parts of, 167 preparation of, in bicuspids and molars involving the occlusal surface, 212 — buccal and labial, 272 — for fillings, 165 — for inlays, 271 — for restoration of incisal tips, 276 preparation of simple proximal cav - ties in incisors and cuspids, 274 — in occlusal surfaces of bicuspids and molars, 279 — involving the proximal and oc- clusal surfaces of bicuspids and molars, 277 — proximal cavities involving the incisal angle, 274 — proximal in incisors and cuspids involving incisal angle, 202 steps in formation of, 168 Cement, 250 for inlays, 292 Cemental fusion of roots, 451 Cementoblasts, 83 Cementum, 73 Central incisor, lower, 10 upper, 3 Cervical clamps, 158 Characteristics of normal occlusion, 611 Chemical constituents of enamel, 63 — composition of saliva, no Chemistry of pulp decomposition, 349 Children's teeth, treatment of, 385 Chisels, 183 Chloroform, 226, 227 Choice of metals for appliance (orthodon- tia), 848 Chronic alveolar abscess, 362 Clamp bands, adjustment of anchor, 705 Clamps, 157 Classification of cavities, 166 chart (orthodontia), 652 malocclusion, 651 Closing up spaces between incisors, 715 Coagulating agents, 355 Cocain, 224 hydrochlorid, 402 Cold, 221 ComlDination filings, 255 amalgam and cement, 256 cement and gutta-percha, 257 gold and amalgam, 256 gold and cement, 256 gold and tin, 256 platinum and gold, 255 Comparative measures of resistance (or- thodontia), 679 Complications incident to removal of pulp, 338 . f T. in treatment after extraction of teeth, 814 INDEX 883 Conditions necessitating removal of pulp, 3.25 Conservation of anchorage, 693 Construction of complicated retaining ap- pliances, 861 Construction of gold inlays, 305 difficult cavities filled by the Taggart method, 309 posts for cast gold inlays, 311 Co-ordination of functions, 616 Corrected radius (orthodontia), 663 Correction of lines of exerted force in expansion arch, 700 Cotton for separating, 139 Crown, 2 Curve of Spec, 614 Cuspid, elevation of (orthodontia), 715 extrusion of, 715 Cuspid, the lower, 1 7 cervical margin, 18 cusp, 18 distal surface, 18 labial surface, 17 lingual surface, 18 mesial surface, 18 pulp cavity, 18 root, 18 Cuspid, the upper, 14 Cusps, 2 Cutting of the flap, 480 Daily records, 528 Deciduous: arch, 830 cuspids, results of extraction of, 808 laterals, results of extraction of, 808 lower central incisors, 57 lower cuspid, 58 first molar, 58 lateral incisor, 57 second molar, 59 molars, results of extraction of, 810 teeth, materials for filling, 387 premature loss of, 647 prolonged retention of, 646 pulps and abscesses in, 366 upper central incisor, 54 cuspid, 55 first molar, 56 , lateral incisor, 55 second molar, 57 Decomposition of the pulp, 349 Deductions from early symptoms of de- veloping malocclusion, 625 Definition of matrix, 259 Dental: cabinet, 91 caries, 119 engine, 185 pulp, 76 Dentin, 69 histological constituents of, 69 treatment of sensitive, 219 Dento-facial orthopedia, 617 Denture, normal human, i Denuded end of root, 367 Deposits, 107 removal of, 114 serunaal, 112 Designation of malpositions of teeth, 651 Details as to manipulation of matrix, 264 Development of associated anatomica structures, 615 Developmental spaces (orthodontia), 606 Deviation of the nasal septum, 640 Devitalization of dental pulp, 334 Diagnosis: class II, 765 class III, 789 class IV, 805 orthodontia, 649 pyorrhea, 493 radiographic, 666 Diagram, Dr. Bonwill's, 658 Dr. Hawley's, 658 Direction of growths of dental arches, 606 Discolorations of teeth, causes and treat- ment of, 375 Discomfort in mastication, 388 Disease (orthodontia), 631 Dislocation of lower jaw, 451 Distal movements of molars, 723 Distance between holes in rubber dam, 151 Distribution of plaster in the tray (ortho- dontia), 867 Divided expansion arc, 689 Division of teeth and cavities, 168 Double resection of the mandible, 801 Drilling of the socket, 480 Drug irritants, 343 Dynamics, 668 arch: — expansion, 676 divided, 677 double, 679 gauge of, 676 production of force, 677 — sectional, 677 economy of force, 679 contraction of silk, 675 definition, 668 effect of force on tooth movement, 668 elasticity of flexion, 671 — of rubber, 673 — of stretching of soft wire, 675 — of torsion, 672 elementary force-producing machines, 670 — jackscrew, 671 — screw, 670 — spring, 671 — traction screw, 671 interdental elastic force, 673 intermaxillary force, 674 lever, 672 movements, 669 — bodily, 669 — extruding, 670 — inclination, 669 — intruding, 670 — rotating, 670 requirements in orthodontia, 668 wheel and axle, 673 884 INDEX Early treatment of arrested developmen- tal conditions in the arches, 735 Efficiency of appliances (orthodontia), 692 Electric current, 221 furnace, 302 Electrical units of measurements, 601 Elevation of cuspid (orthodontia), 715 Employment of matrix for gold restora- tions, 261 Enamel, 62 chemical constituents of, 63 rods, 64 strength of, 69 wall, proper bevel and polish of, 178, 201 Encystment of root, 368 Engine, the dental, 185 Environment (orthodontia), 627 Epithelial structures, 83 Erosion, 307 treatment of, 515 Erosions, no Eruption of the teeth, 428 Escape of a tooth into the larynx or pharynx, 451 Escharotics, 222 Establishing sinus, 365 Ether, 226 Ethyl chlorid, 226, 399 Etiology: and diagnosis of class I, 738 and diagnosis of class II, 765 and diagnosis of class III, 789 orthodontia, 625 pyorrhea alveolaris, 487 Eugenol, 225 Examination of teeth to discover cavities, 131 cleanliness, 132 concluding notes, 134 conditions for examination, 132 diagnosis, 131 dryness, 132 gingival, 131 lines of union, 131 marginal, 132 physical exploration, 131 proximal, 131 records, 134, 528 regional divisions for, 131 at stated periods, 131 system and method, 132 systematic record, 131 Excessive overbite, 771 Excision of root, 369 Exclusion of moisture from teeth during operations, 149 Expanded arch, retention of, 828 Expansion: arch, spurs and hooks for, 857 vertical alignment of, 701 Extension for prevention, 171 External anatomy, relations of (orthodon- tia), 621 Extraction, 419 after-pains of, 454 after-treatment of, 455 Extraction, alveolar hemorrhage from, 452 casualties attending, 451 compl cations in treatment after, 814 deciduous, 447 — cuspids, results of, 808 — laterals, results of, 808 — molars, results of, 810 first permanent molars, results of, 812 of impacted teeth, 459 of wrong tooth, 451 permanent, evil effects of, 811 problem of (orthodontia), 806 roots, 448 second bicuspids, result of, 813 shock during, 452 sterilizing instruments for, 455 under anesthetic agents, 455 Extruding bicuspids, 727, 728 Eye-strain, 87 Facial asymmetry, 623 — profile, 619 — symmetry, 619 Faucial tonsil, hypertrophy of, 640 Fees, 537 Fibroblasts, 83 Filling: deciduous teeth, 387 the impression (orthodontia), 86f large canals, 372 materials, 229 the matrix for inlays, 284 root canals, 355, 371 small canals, 373 the use of the matrix for, 259 Fillings, preparation of cavities for, 165 Fissure cavities, 170 preparation of, 187 Fixation: of expansion arch, 703 principle of, 681 Floor of pulp chamber, 24 Fluxes, 852 Force and resistance (orthodontia), 668 appliances for producing, 670 Forcing teeth or roots into antrum, 452 Forms of the matrix, 260 Fracture (extraction): of alveolar process, 451 of crown of tooth, 451 of jaws, 451 Frenum labium, abnormal, 649 operation for, 763 Full bimaxillary infra-occlusion, 656 Functional influences (orthodontia), 630 Fundamental pathological conditions in malocclusion, 650 Furnaces, 299 Furnaces, electric, 302 gasoline, 303 Fusing porcelain, 286 Fusion of the roots, cemental, 451 Gasoline dental furnace, 303 Gassing, 301 Gelatinous plaques, 123 INDEX 885 General anodynes or analgesics, 226 Gingival margin, 2 Glossary (Rontgen ray), 600 Gold, 229 and amalgam, 256 and cement, 256 and platinum, 255 and tin, 256 inlays, construction of, 305 Green stain, 108 Growth of dental arches, 606 Gutta-percha, 253 and cement, 257 fillings, 266 for separating, 138 Gum lancets, 450 Hand matrix, 263 Harmony of facial profile, 619 Hawley's diagram, 658 Heat, 220 Heredity (orthodontia), 627 Histological constituents of dentin, 69 Histology of the human teeth, 60 Hoes in rubber dam, 150 distance between, 151 location of, 152 Hooks for expansion arch, 857 Human denture, normal, i teeth, the anatomy of, i — the histology of, 60 Hygiene of the mouth, 97 in operating room, 85 Hypertrophy of faucial tonsil, 640 of turbinated bones, 641 Hypodermic armamentarium, 406 Injection, technique of, 408 Immunity to decay, period of, 124 Impacted lower third molars, treatment of, 459 definition, 459 class I, 460 class II, 462 Implanting teeth, 477 Impressions (orthodontia): assembling the, 868 filling the, 869 materials and models for, 865"! sectioning and removal of, 870 tray, 866 varnishing tray, 869 Imcisor: lower central, 10 — cervical margin, 12 — deciduous, 56 — distal surface, 12 — incisive edge, 12 — labial surface, 10 — lingual surface, 11 — mesial surface, 12 — pulp cavity, 13 — root, 13 lateral, 13 — deciduous, 57 mesial and distal movements of (or- thodontia), 606 Incision : upper central, 3 — cervical margin, 6 — cervical ridge, 4 — cingulum, 4 — deciduous, 54 upper central, distal surface, 5 — labial surface, 3 — lingual surface, 4 — mesial surface, 5 — pulp canal, 6 — pulp cavity, 6 — pulp chamber, 6 — root, 6 lateral, 7 — cervical margin, 9 — deciduous, 54 — distal surface, 9 — incisive edge, 9 — labial surface, 7 — lingual surface, 8 — mesial surface, 9 — pulp cavity, 10 — root, 9 Incisive edge, 2 Indications for the planting of teeth, 478 Infant, oral hygiene of the, 97 Inflammatory changes in alveolar tissue, 631 Influence of the pituitary body, 629 Infra-occlusion, 653 anterior teeth, 759 bilateral of bicuspids and molars, 653 class II div. I (orthodontia), 776 full bimaxillary, 656 of incisors, cuspids and bicuspids, 653 and cuspids, 757 of molars and bicuspids, 761 treatment of, 728, 733 variations of, 653 Inharmony of the profile, 623 Inlays, 267 gold, construction of, 305 indications for use of, 267 porcelain, 281 posts for cast gold, 311 preparation of cavities for, 271 the Taggart method, 306 Irritants, drug, 343 mechanical, 344 Instruments: employed for extraction of teeth, 430 for preparation of cavities for fillings, 1 82 — chisels, 183 — cutting edge, 183 — handle, 183 — hatchets, 183 — hoes, 183 — shank, 183 — spoons, 183 sterilization of, 93, 455 Intermajtillary, anchorage (orthodontia 687 retention, 826 Internal anatomy, relations of (ortho- dontia), 621 886 INDEX Interproximal spaces, 53 Intra-uterine influence upon arch develop- ment, 626 Lancets, 450 Large canals, filling of, 372 Lateral incisors: deciduous lower, 57 upper, 54 the lower, 13 the upper, 7 Layer of Weil, 77 Lever, 726 Ligating the teeth, 154 Ligatures, 710 as auxiliaries in anchorage, 694 care of, 878 variety of, 710 Light, 221 Lingual bar and ligature, 714 arch retainer, 833 movements of incisors, 732 Lip-biting, 648 Local anesthesia, 393 anodynes, 223 means of producing, 395 Location of holes in rubber dam, 152 Loops, bending of, 731 Lower cuspid, 17 first bicuspid, 27 molar, 44 second bicuspid, 30 molar, 49 third molar, 52 Magill band, 854 accessories to, 856 Malocclusion, 611 classification of, 651 fundamental pathological conditions in, 650 local factors In, 646 Malrelation of dental arches, 651 Management of large proximo-occlusal cavities in pulpless bicuspids, 217 in pulpless molars, 217 of an ofiice practice, 519 Mandible: double resection of, 801 Mastication, discomfort in, 388 Materials for construction of appliance (orthodontia), 848 for filling deciduous teeth, 387 Matrix : definition of, 259 _ details as to manipulation of, 264 employment of, for gold restorations, 265 filling of, for porcelain inlay, 284 the hand, 263 introduction and management of, 264 materials and forms of, 260 mechanical, 260 for porcelain inlay, 281 removal of, 265 the use of, in filling teeth, 259 Measuring the force of expansion, 717 Mechanical: advantage (orthodontia), 692 irritants, 344 separator, 142 advantages of, 145 Medication (pyorrhea alveolaris), 503 Menthol, 225 Mesial and distal movements of incisors, 716 of anterior teeth, 732 Metals for appliances, choice of (ortho- dontia), 848^ Method of anesthetizing the pulp, 415 Methods of removing the pulp, 326 Mixing of plaster, 866 Models (orthodontia): marking and numbering of, 876 necessity, for accurate, 864 trimming the, 872 Moisture, exclusion of, from the teeth, 149 Molar: clamp band, 859 assembling parts of, 859 deciduous, 55, 56, 57, 58 distal movements of (orthodontia), 723 lower first, 44 — buccal, 47 — distal, 48 — lingual, 48 — mesial, 48 — occlusal, 44 — pulp cavity, 49 — roots, 48 second, 49 — buccal, 50 — distal, 50 — lingual, 50 — mesial, 50 — occlusal, 49 — pulp cavity, 52 — roots, 50 third, 52 — pulp cavity, 52 — roots, 52 — surfaces, 52 upper first, 31 — buccal, 34 — cusps, 32 — distal, 36 — fossae and grooves. ^^ —lingual, 35 — mesial, 35 — occlusal, 31 — pulp cavity, 37 — roots, 36 second, 38 — buccal, 39 — distal, 40 — lingual, 40 — mesial, 40 — occlusal, 38 — pulp cavity, 41 — roots, 41 third, 41 — buccal, 42 INDEX 887 Molar: upper third distal, 43 — lingual, 42 — mesial, 43 — occlusal, 42 — pulp cavity, 43 — roots, 43 Mouth-breathing, 635 examination for, 768 Mouth, hygiene of, 97 Mouth-wash, preparation for, 106, 107, 880 Muscular action, normal (orthodontia), .630 Mutilation of the maxillary tuberosity, 45 2 Nasal breathing, obstructions to, 638 Nasal septum, deviation of, 640 Nearly exposed pulps, treatment of, 319 Necessity, for accurate models (ortho- dontia), 864 for retention (orthodontia), 820 Neck of the tooth, 2 Nerves of the pericementum, 84 Nerves of the pulp, 79 Nitrous oxid, 227 Nomenclature: cavity, 165, 167 Normal development of associated anat- omical structures of the internal face, 615 human denture, i muscular action (orthodontia), 630 occlusion, characteristics of, 611 overbite, 768 Notification of patients, 535 Novocain preparation, technique of injec- tion of, 408 Obstructions to nasal breathing, 638 Obtundants, 496 Occipital, anchorage, 689 retention, 827 Occlusal: relations, 607 — of permanent teeth, 609 retention, 822 surface, 2 — cavities, preparation of, 212 Occlusion : definition of, 611 line of (orthodontia), 666 normal, 514, 610 — characteristics of, 611 transition period of, 608 Office practice, management of, 519 Oil burners, 304 of cloves, 225 Operating chair, the window in front of, 86 room, asepsis in, 89 hygiene and arrangement of light in, 8s Operation for abnormal frenum labium, 763 Operative: technic (orthodontia), 696 treatment, technic of (orthodontia), 790 Opium, 226 Oral hygiene of the infant, 97 Ordinary pericementitis, treatment of, 343 Orthodontia, 603 scope of, 603 trend of modern theory and practice, 604 Orthopedia, dento-facial, 617 Osteoblasts, 83 Osteoclasts, 83 Oxidation method (discolorations), 380 removal of, 850 Pathology of dental caries, 119 Pericemental abscess, treatment of, 370 Pericementitis, 343 Pericementum, 80 Period of immunity to decay, 124 Permanent teeth, during childhood, treat- ment of, 389 evil effects of extraction of, 84 Personal treatment of patients, 525 Phenol, 222, 225 Physical : agents, 220 explorations of teeth, 131 relations of beauty, 617 Physiologic action of anesthetics, 396 Pit and fissure cavities, preparation of, 187 Pituitary body, influence of, 629 Plain bands (orthodontia), 854 Planes, relation of inclined, 612 of the teeth, 168 Planting of teeth, 473 Plaster: mixing of, 866 technic, 864 Platinum and gold, 225 Plier, arch-removing, 704 Pneumatic spray, 879 Porcelain: bodies, 297 inlay, 281 section attachment, 291 Position of operator and patient (extrac- tion), 429 Posts for cast-gold inlays, 311 Post-natal factors in arch development, 627 Practical case, ideal treatment of, 78 Preparation of cavities: in bicuspids and molars which involve in the occlusal surface, 212 in bicuspids and molars which do not ir^volve the occlusal surface, 210 buccal and lingual margins, 171 bevel and polish of enamel wall, 178 burs for, 185 cavity nomenclature, 165, 167 classification of cavities, 166 definitions, 165 dental engine, 185 developmental grooves, 171 divisions, of cavities, 168 —of the teeth, 168 extension for prevention, 171 for fillings, 165 888 INDEX Preparation of cavities: fissure cavities, 170 general conditions of outline form, 168 for inlays, 271 instruments for, 182 lower incisor and cuspid cavities, 202 management of large cavities in pulp- less molars, 217 management of large proximo-occlu- sal cavities in pulpless bicuspids, 217 proximal cavities in incisors and cus- pids which involve the incisal angle, 202 proximal cavities which do not in- volve the incisal angle, 195 pulpless incisors having large proxi- mal cavities, 209 resistance form, 175 retention form, 177 sharpening of instruments, 186 Preparation of cavities: smooth surface cavities, 191 steps in cavity formation, 168 Preparation for mouth wash, 106, 107 Precautions in planting teeth, 478 Premature loss of deciduous teeth, 647 Preservative forces of arch integrity (orthodontia), 613 Prevention of thumb-sucking, 648 Principle of fixation, 681 Problem of extraction (orthodontia), 806 Procedure for planting teeth, 479 Profile, inharmony of, 623 Prognosis, caries, 129 in planting of teeth, 476 Prolonged retention of deciduous teeth, 646 Proper bevel and polish of enamel wall, 178 Prophylaxis, 878 Proximal surface, 2 Proximo-occlusal cavities in pulpless bi- cuspids, 217 Pulp, 76 anesthetization and devitalization of, 325. 326, 334, 415 capping the, 320 complications incident to removal of, 338 conditions necessitating removal of, 325 methods of removing, 326 nerves of, 79 partially alive, 359 removal and subsequent treatment of, 325 treatment of putrescent, 355. 359 Putrescent pulp in deciduous teeth, treat- ment of, 366 Pyorrhea alveolaris, 487 diagnosis of, 493 etiology and pathology of, 487 medication for, 503 obtundents for, 496 retainers for, 496 subsequent treatment, 505 Pyorrhea alveolaris surgical treatment, 498 systemic treatment, 506 treatment of, 493 Qualifications of appliances (orthodontia), 692 Radiographic diagnosis, 666 Readings from casts, 864 Reception of patients, 524 Reciprocal anchorage, 690 Reduction method (discolorations), 380 Re-inforced anchorage (orthodontia), 683 Relations: of beauty, physical, 617 of external and internal anatomy, 621 of inclined planes, 612 of internal secretory organs to mal- occlusion, 628 of overbite and length of tooth cusps, 614 Relative value of first permanent molar, 811 Removal : of adventitious growths, 643 of deposits, 114 of impression (orthodontia), 870 and subsequent treatment of pulp, 325 — anesthetization for, 326 — complications, incident to, 338 — conditions necessitating, 325 — methods of, 326 Repairing defects in impressions and models (orthodontia), 876 Replanting teeth, 473 Resection of the mandible, double, 801 Resistance, form for prepared cavities, 175, 203 comparative measures of (orthodon- tia), 679 values in anchorage (orthodontia), 576 _ Results of extraction of deciduous cuspids, laterals and molars, 808, 810 of first permanent molar, 812 of second bicuspids, 814 Retainer, the lingual arch, 833 Retainers (pyorrhea alveolaris), 496 Retaining appliances, construction of, 861 wires, 731 Retention form for prepared cavities, 177, 204 Retention (orthodontia), 820 after anterior expansion, 719 after bodily movements of teeth, 828 anterior part of developing arch, 829 anterior part of permanent arch, 83a classified, 822 of changes in the occlusal plane, 836 of class II, 838 of class III, 846 of corrected infra-occlusion of molars, 837, 845, of corrected infra-occlusion of bicos- pids, 845 INDEX 889 Retention (orthodontia), expanded arch, 828 field of, 827 intermaxillary, 826 intermaxillary in, class II, 840, 844 of entire deciduous arch, 830 of entire permanent arch, 834 of malocclusion of individual teeth, 828 of mesio-distal changes in occlusion, 827 necessity for, 820 occipital, 827 occlusal, 822, 824 reciprocal, 825 simple, 824 Rontgen ray, 541 adjustment, 556 apparatus, 546 box, developing, 570 — examining, 582 characteristics of X-ray, 584 coil, 547 . compression diaphragm, 559 current, inverse, 554 dangers, 542 developers, temperature, 573 developing agents, testing, 579 developing paraphernalia, 571 electrical units of measurements, 601 films, 560 — bromide paper, 576 — care of, 563 — consulting photographer, 576 — cutter, 564 — deterioration of, 576 — enclosing, 564 — hardening, 574 — holders, 561 — lead backing, 576 — making photographic prints, 576 —packet, 565 — preparation board, 563 — sizes of, 576 —testing, 577 fluoroscope, 550 focal distance, 569 glossary, 600 head rest, 549 history of Rontgen ray, 541 hypo, test for, 574 interrupter, 547 inverse, 557 —current, 554 measurements, electrical units of, 601 meters, 549 nomenclature, 541 penetrameter, 551 peridental membrane, 583 plant, 545 — testing of, 565 posing the patient, 567 ray, secondary, 584 rays, strength of, 556 rheostat, 548 room, X-ray, 545 ruby lamp, testing, 581 safety of operator, 544 Rontgen ray: safety of patient, 544 screen protection, 551 —intensifying, 553 skiagraphs: — examining, 581 —filing, 577 —improving, 575 — interpretation, 582 — marking, 578 — recording, 579 —taking, 570 stereographs, 593 third terminal, 557 tubes: — connecting X-ray tubes, 55'* — exclusion, 559 —rock, 558 —stand, 557 — suggestions for use, 555 —X-ray, 553 uses of ray, 584 vacuum, regulation, 556 — to raise vacuum, 555 value of ray, 584 visible hemisphere, 556 X-ray room, 545 tubes, 553 Root, 2 absorbed, 368 artificial, 484 denuded end of, 367 excision of, 369 encystment of, 368 Root canals, filling of, 371, 372, 373 Rotation of molars (orthodontia), 725 of incisors, 731 of teeth with levers, 726 Rubber dam: the use of, 150 adjusting, 152 cervical clanips, 158 clamps, 157 distance between holes, 151 holes, 150 ligating the teeth, 154 location of holes, 152 number of teeth isolated, 152 rubber cups, cotton rolls, napkins,'i6o saliva ejector, bibs and accessories, 160 size and shape of, 150 use of absorbents, 161 Rubber for separating, 140 Sajou's theory, 642 Saliva, chemical composition of, no ejector, 160 Scope of orthodontia, 603 retention (orthodontia), 820 Screw post, technique of inserting, 217 Secondary abscess pocket, 369 Sectional arch and its advantages, 728^ Sectioning and removal of impression, (orthodontia), 870 Sensitive dentin, treatment of, 219 Separation of teeth, 137 cotton for, 139 890 INDEX Separatiop of teeth, gutta-percha for, 138 miscellaneous conditions requiring, 146 previous-slow wedging, 138 rubber for, 140 tape for, 141 wood for, 141 Separator: the best, 142 the mechanical, 142 Serumal deposits, 112 Shading, 295 Sharpening instruments, 186 Shock during tooth extraction, 452 Shoeing, 208 Silver nitrate, 223 Simple anchorage, 683 retention, 824 Simplified method (orthodontia), 659 Smooth surface cavities, 191 Socket, drilling of the (planting), 480 Soldering the band, 855 requirements, 849 technic, 851, 861 Spaces, developmental (orthodontia), 606 Sprays, pneumatic, 879 Spurs, 713 for expansion arch, 857 pliers, 713 stationery, 538 Steps in cavity formation, 168 Stereographs, 593 Sterilization of instruments, 93, 455 Sterilizing agents, 485 Stomatitis, 106 Subsequent treatment (pyorrhea), 505 Summary of anchorage principles, 695 Superficial defects, 170 Supernumeraries, 648 Surfaces of teeth, 2 buccal, 3 labial, 2 lingual, 3 proximal, 2 Surgical treatment (pyorrhea), 498 Symmetry of the face, 617, 619 Symptoms of developing malocclusion deductions from, 625 Syncope, 451 Systemic treatment (pyorrhea), 506 Table of average measurements, 661 Taggart method, cast inlay, 306 difficult cavities filled by, 309 Tape, 141 Technique: constructive, 847 instruction, advantages of (orthodon- tia), 847 plaster, 864 of inserting a screw post, 217 of novocain, injection, 408 Teeth: anatomy of the human, i anatomical parts of, 2 arches of temporary, 605 deciduous, 53 Teeth: eruption of, 428 examination of, to discover carious cavities, 131 extraction of, 419 — deciduous, 447 forcing into antrum (extraction), 452 histology of the human, 60 — impacted, extraction of, 459 implanting of, 477 loss of permanent, 647 materials for filling deciduous, 387 neck of, 2 occlusal relations of permanent, 609 planting of, 473 replanting of, 473 separation of, 133 transplanting of, 477 treatment of discolorations of, 375 treatment of putrescent pulps and abscesses in deciduous, 367 use of matrix in filling, 259 Temporary teeth, arches of, 510 Therapeutics for obtunding sensitive den- tin, 220 Thrush, 104 Thumb-sucking, 648 Tin, 249 Tipping up molars (orthodontia), 724 Tooth: alveolar hemorrhage from extraction of, 452 angle of, 2 casualties attending extraction of, 451 escape of into larynx or pharynx, 451 extraction of the wrong, 451 Treatment: of children's teeth, 385 of discolorations of teeth, 375 of exposed or nearly exposed pulps, 319 of infra-occlusion, 728, 733 — complications in, after extraction of teeth, 814 — early of class II, 768 — of arrested development, early (orthodontia), 735 — of class I, 738 — of class II, 765, 768 — of class II, div. I, 776 — of class II, div. I, sub. div., 781 — of class II, div. II, 782 — of class II, div. II, sub. div., 785 — of class III, 789 — of class IV, 805 — impacted lower third molars, 459 — of special cases, 742, 772 — technic of operative, 776, 790 of permanent teeth during childhood, 389 of pyorrhea alveolaris, 493 — erosion, 515 — subsequent, 505 — surgical, 498 — systemic, 506 of sensitive dentin, 219 Trichloracetic acid, 223 Trimming the model (orthodontia), 278 INDEX 891 Unilateral expansion of the dental arch, Varnishing the impression (orthodontia) 721 869 Use of the matrix, 259 of the rubber dam, 150 Uses of intermaxillary anchorage (ortho- dontia), 687 Utilization of time in the ofSce, 526 Variations of infra-occlusion, 653 of overbite, 755 Variety of ligatures, 710 Weil, the layer of, 77 Window in front of operating chair, 86 Wood for separating, 141 Wrenches, 709 Young blowpipe, 850 Zinc chlorid, 222 COLUMBIA UNIVERSITY LIBRARY Thi, hook is due on the date indicated below, or at the e.pirn°:'rdefinitepeHodaf^rthed^^^ as provided by the rules of the Library or oy p rangement with the Librarian in charge. C2a(239)M100 RK501 Johnson . J62 1915 A text-book of operative dentistry 2002399318 AUG 4 ICZ?