RK501 K63 2^l?^'i^^' HX64072258 The American texf-b RECAP 133 [g|[inj Tin][rugr nHlfrugfr5TJfiM^M I i 1 1 1 1 1 i i i i THE LIBRARIES [E 1 COLUMBIA UNIVERSITY HEALTH SCIENCES LIBRARY la [^ ru^fiui]nTnJirinJFiTfil[iifgrnKI|^ m i i Digitized by the Internet Archive in 2010 with funding from Open Knowledge Commons http://www.archive.org/details/americantextbook1897kirk LIST OF CONTRIBUTORS. ANDREWS, R. R., A.M., D.D.S., F.R.M.S. BURCHARD, HENRY H., M. D., D. D. S. ; CASE, CALVIN S., M. D., D. D. S. ; CHRISTENSEN, WILLIAM E., D. D.S.; CLAPP, DWIGHT M., D.M.D.; CRYER, M. H., M.D., D.D.S.; DARBY, EDWIN T., M.D, D.D.S.; GODDARD, C. L., D.D.S.; GUILFORD, S. H., A.M., D. D. S., Ph.D.; JACK, LOUIS, D.D.S. ; KIRK, EDWARD C, D.D.S. ; OTTOFY, LOUIS, D. D.S. ; PEIRCE, C. N., D.D.S. ; THOMAS, J. D., D.D.S.; THOMPSON, ALTON HOWARD, D.D.S. THE AMERICAN TEXT-BOOK OPERATIVE DENTISTRY IN CONTRIBUTIONS BY EMINENT AUTHOBITIES. EDITED BY EDWARD C. KIRK, D.D.S., Peofessor of Clinical Dentistky in the University of Pennsylvania, Philadelphia; Editor of " The Dental Cosmos." ILLUSTRATED WITH 751 ENGRAVINGS. LEA BROTHERS & CO., PHILADELPHIA AND NEW YORK 1897. Entered according to Act of Congress in the year 1897, by LEA BROTHERS & CO., in tlie Office ol' the Librarian of Congress, at Washington. Ail rights reserved. WESTCOTT Ik THOMSON, PRESS OF ELECTROTYPEHS. PHILAOA. WILLIAM J. DORNAN. PHILADA. WITH THE CONSENT OF THE CONTRIBUTOKS THIS BOOK IS DEDICATED TO JAMES TRUMAN, D.D. S., THE CHARACTERISTIC OF WHOSE LONG PROFESSIONAL CAREER HAS BEEN THE INCULCATION OP THE PRINCIPLES UPON WHICH THE WORK IS BASED. PREFACE. The developments which have takeu place since the principles and art of Operative Dentistry were last gathered in text-book form may be said to have revolutionized the subject. So rapid has been its growth, and so pronounced has been the tendency to specialization in this as in other departments of dentistry, that the field has grown beyond the capacity of any single writer to represent it adequately. The com- posite plan of authorship therefore became necessary for securing a complete record of the ripest thought on the subject. The aim of the editor has been to secure a homogeneous treatment of the mass of data presented. The importance of a due recognition of the relation of principles to practice is appreciated by all who are concerned in the education of dental students, and has been kept constantly in mind by each of the contributors to this work. It has been written especially with a view to the needs of students of dentistry, and to that end scientific prin- ciples have been emphasized, and the descriptive data included are so treated as fully to embrace and illustrate the principles taught. The work is essentially a new departure ; old traditions have been subjected to critical study and rejected when found obsolete, or re-stated when their value was evident. The plan followed is one which it is hoped has resulted in a practical exposition of all that may be fairly included under the title adopted, so arranged and presented as to meet the requirements of those for whom it was written. Where statements are made they are either those of verified fact or are based upon deduc- tions which may be said to be Avarranted by existing knowledge. In a work of composite authorship it is unavoidable that differences of opinion as to the choice of nomenclature should frequently arise. It would be manifestly confusing as well as misleading to the student to meet with differences in the terms employed by different contributors for expressing the same idea. To avoid this the responsibility of har- monizing these differences has been assumed by the editor. In determining the range of topics which may be properly classified as coming within the field of Operative Dentistry the editor has been guided by the principle of distinguishing all those procedures the per- formance of which includes operative work upon the mouth as belong- 8 PREFACE. ing to operative, and all those which are performed in the laboratory as pertaining to prosthetic dentistry. Although, as a general rule, this distinction is sufficiently accurate, there are nevertheless instances where the two divisions merge and where certain operations cannot be said to belong exclusively to either class. This is notably true of ortho- dontia and of crown- and bridge-work. As the present volume is a companion to one already issued under the editorship of Prof. Essig dealing exclusively with Prosthetic Dentistry, in which crown- and bridge-work is treated exhaustively, that subject has not been in- cluded in this volume other than by occasional allusion. Orthodontia has, however, been elaborately presented purely as an operative procedure. It is that aspect of the subject which first presents itself to the operator in the consideration of irregularity cases, and it is here treated in a way to furnish a practical answer to the question, What shall be done for its correction? Dental Anatomy, Histology, and Embryology are so clearly funda- mental to a proper understanding of operative methods and a rational technique in practice that they are included as a part of the work. It will be seen that the volume has three principal divisions — viz. I. Dental Anatomy ; II. Operative Dentistry ; III. Dental Orthopedia. The last includes, besides the well-recognized department of ortho- dontia, the modification of facial contours, in which such large possi- bilities for the application of esthetic talent and mechanical skill have been foreshadowed by the demonstrations of its originator, Dr. Case. The thanks of the editor are due to the contributors for the uniform courtesy with which they have yielded to changes suggested for the purpose of securing harmony of literary treatment throughout the work ; to the publishers for their liberal policy in securing an excellent technical result; to Drs. Farrar, Talbot, Ottolengui, Guilford, and Angle ; and to H. D. Justi & Co., The Wilmington Dental Mfg. Co., and The S. S. White Dental Mfg. Co., for the use of illustrations. The editor desires here to acknowledge his grateful appreciation of the assist- ance rendered by Prof. H. H. Burchard, who from the inception to the completion of the work, in all its phases, has by wise counsel, intelli- gent criticism, and skilled effort largely contributed to the attainment of whatever excellence it may be found to possess. E. C. K. LIST OF CONTRIBUTORS. E. E. ANDEEWS, A. M., D. D. S., F. E. M. S., Cambridge, Mass. HENEY H. BUECHAED, M. D., D. D. S., Special Lecturer on Dental Pathology and Therapeutics, Philadelphia Dental Col- lege, Philadelphia. CALVIN S. CASE, M. D., D. D. S., Professor of Orthodontia, Chicago College of Dental Surgery, Chicago, III. WILLIAM E. CHEISTENSEN, D. D. S., Philadelphia. Munich. DWIGHT M. CLAPP, D. M. D., Clinical Lecturer on Operative Dentistry, Dental Department, Harvard L^niversity, Boston, Mass. M. H. CEYEE, M. D., D. D. S., Assistant Professor of Oral Surgery in the University of Pennsylvania, Philadelphia. EDWIN T. DAEBY, M. D., D. D. S., Professor of Operative Dentistry and Dental Histology in the University of Penn- sylvania, Philadelphia. C. L. GODDAED, D. D. S., Professor of Orthodontia, University of California, College of Dentistry, San Francisco, Cal. S. H. GUILFOED, A. M., D. D. S., Ph.D., Professor of Operative and Prosthetic Dentistry and Dean of the Philadelphia Dental College, Philadelphia. LOUIS JACK, D. D. S., Philadelphia. 10 LIST OF CONTRIBUTORS. EDWARD C. KIRK, D. D. S., Professor of Clinical Dentistry in the University of Pennsylvania, Philadelphia, and Dean of the Department of Dentistry. LOUIS OTTOFY, D. D. S., Professor of Clinical Therapeutics, Chicago College of Dental Surgery, Chicago ; formerly Dean and Professor of Dental Pathology, American College of. Dental Surgery, Chicago, 111. C. N. PEIRCE, D. D. S., Professor of Dental Physiology, Dental Pathology, and Operative Dentistry, and Dean of the Pennsylvania College of Dental Surgery, Philadeljihia. J. D. THOMAS, D. D. S., Lecturer on Nitrous Oxid, Department of Dentistry, University of Pennsylvania, Philadelphia. ALTON HOWARD THOMPSON, D. D. S., Professor of Dental Anatomy, Kansas City Dental College, Kansas City, Mo. CONTENTS. CHAPTER I. PAGE MACKOSCOPIC ANATOMY OF THE HUMAN TEETH 17 By Altox Howard Thompson, D. D. S. CHAPTER II. THE EMBEYOLOGY AND HISTOLOGY OF THE DENTAL TISSUES . . 53 By B. R. Andrews, A. M., D. D. S., F. R. M. S. CHAPTER III. THE EXAMINATION OF TEETH PKELIMINARY TO OPERATION- METHODS, INSTRUMENTS, APPLIANCES— RECORDING RESULTS, ETC 93 By Louis Jack, D. D. S. CHAPTER IV. PRELIMINARY PREPARATION OF THE TEETH— REMOVAL OF DEPOSITS AND CLEANING OF THE TEETH— WEDGING-OTHER METHODS OF SECURING SEPARATIONS— EXPOSURE OF CERVI- CAL MARGINS BY SLOW PRESSURE, ETC 100 By Louis Jack, D. D. S. CHAPTER V. PRELIMINARY PREPARATION OF CAVITIES— TREATMENT OF HY- PERSENSITIVE DENTIN BY SEDATIVES, OBTUNDENTS, LOCAL AND GENERAL ANESTHETICS— STERILIZATION, WITH A BRIEF CONSIDERATION OF THE PHYSIOLOGICAL AND THERAPEUTIC ACTION OF THE MEDICAMENTS USED 108 By Louis Jack, D. D. S. 11 12 COXTEXTS. CHAPTER VI. PAGE PREPARATION OF CAVITIES— OPENING THE CAVITY— REMOVING THE DECAY- SHAPING THE CAVITY— CLASSIFICATION OF CAVITIES 133 By S. H. GJuilford, A. M., D. D. S., Ph. D. CHAPTER VII. EXCLUSION OF MOISTURE— EJECTION OF THE SALIVA— APPLICA- TION OF THE DAM IN SIMPLE CASES, AND IN SPECIAL CASES PRESENTING DIFFICULT COMPLICATIONS— NAPKINS AND OTHER METHODS FOR SECURING DRY^NESS 157 By Louis Jack, D. D. S. CHAPTER VIII. THE SELECTION OF FILLING MATERIALS WITH REFERENCE TO CHARACTER OF TOOTH STRUCTURE, VARIOUS ORAL CONDI- TIONS AND LOCATION, DEPTH OF CAVITY AND PROXIMITY OF THE PULP— CAVITY LINING, AVITH ITS PURPOSES 167 By Louis Jack, D. D. S. CHAPTER IX. TREATMENT OF FILLINGS AVITH RESPECT TO CONTOUR, AND THE RELATION OF CONTOUR TO PRESERVATION OF THE INTEG- RITY OF APPROXIMAL SURFACES 177 By S. H. Guilford, A. M., D. D. S., Ph. D. CHAPTER X. THE OPERATION OF FILLING CAVITIES WITH METALLIC FOILS AND THEIR SEVERAL MODIFICATIONS 182 By Edwin T. Darby, D. D. S., M. D. CHAPTER XI. PLASTIC FILLING MATERIALS— THEIR PROPERTIES, USES, AND MANIPULATION 219 By Henky H. Burchakd, M. D., D. D. S. CHAPTER XII. COMBINATION FILLINGS 258 By Dwight M. Clapp, D. :M. D. CONTENTS. 13 CHAPTER XIII. PAGE INLAYS 280 By William E. Cheistensen, D. D. S. CHAPTER XIV. THE CONSERVATIVE TREATMENT OF THE DENTAL PULP 294 By Louis Jack, D. D. S. CHAPTER XV. THE TREATMENT AND FILLING OF ROOT CANALS 317 By Henry H. Burchard, M. D., D. D. S. CHAPTER XVI. DENTO-ALVEOLAR ABSCESS . 366 By Henry H. Burchard, M. D., D. D. S. CHAPTER XVII. PYORRHEA ALVEOLARIS 391 By C. N. Peirce, D. D. S. CHAPTER XVIII. DISCOLORED TEETH AND THEIR TREATMENT 420 By Edward C. Kirk, D. D. S. CHAPTER XIX. EXTRACTION OF TEETH 444 By M. H. Cryer, M. D., D. D. S. CHAPTER XIX. (Continued). EXTRACTION OF TEETH UNDER NITROUS OXID ANESTHESIA ... 508 By J. D. Thomas, D. D. S. CHAPTER XIX. (Concluded). LOCAL ANESTHETICS AND TOOTH EXTRACTION 518 By Henry H. Burchard, M. D., D. D. S. CHAPTER XX. PLANTATION OF TEETH ^^^ By Louis Ottofy, D. D. S. 14 CONTEXTS. CHAPTER XXI. PAGE MANAGEME^'T OF THE DECIDUOUS TEETH \ . . 542 By Clark L. Goddard, A. M., D. D. S. CHAPTER XXII. OKTHODONTIA EXCLUSIVELY AS AN OPERATIVE PROCEDURE . . 561 By Clark L. Goddard, A. M., D. D. S. CHAPTER XXIII. THE DEVELOPMENT OF ESTHETIC FACIAL CONTOURS 655 By Calvix S. Case, D. D. S., M. D. INTRODUCTORY. A STUDY of the advances which have of recent years taken place in the field of Operative Dentistry will reveal, beside the important addi- tions to our knowledge in the shape of novel methods and improved technique, a vastly more important advance manifested in a better and more general understanding of scientific principles, and the application of dental science to dental art, resulting in a more rational practice. Especially is this true in regard to the etiology of dental and oral pathological conditions, and the rationale of the modes of treatment indicated for the morbid states constantly confronting the dental practitioner. The modifications in surgical methods and the greatly improved results which are the outgrowth of modern scientific studies in bacterial pathology, while they have made a considerable impress upon dental operative methods, have not, however, received that universal practical acceptance among dental operators which their immense importance demands. There is no field of special surgery in which the import- ance of exact knowledge with respect to aseptic and antiseptic treat- ment is more marked than in the practice of dentistry. The dental operator is continually confronted with septic conditions, so that pre- cise knowledge of their origin, causes, phenomena, and treatment are essentials to the legitimate practice of the profession. The performance of any operation, and especially those which are classified as capital, with unclean hands or infected instruments would in the present stage of surgical art be regarded as criminal malpractice. It should be so considered in dentistry. The loss of a patient's life as the result of surgical septic infection is no longer permissible. Lack of antiseptic precautions in certain dental operations may directly lead to and as a matter of fact has been the cause of fatal results. It has been shown conclusively^ that a lai'ge variety of pathogenic micro- organisms are almost constant inhabitants of the oral cavity. In addi- tion to the numerous forms which bring about an acid reaction, there are many specified organisms which produce in inoculated animals pyemia and septicemia in their several clinical classes. But while the dental practitioner is not often called upon to face the issues of life 1 W. D. Miller, Dental Cosmos^, November, 1891. 15 1 6 lyTE OD UCTOR Y. and death in the course of his work, his responsibilities as related to the issues with which he does deal demand of him the same care and thoroughness in order to attain the character of result which the pos- sibilities of modern dentistry require of him. In the following pages the importance of asepsis and antisepsis in dental operations is con- stantly impressed upon the mind of the student. By the term asepsis is specifically meant the condition under which are excluded those influences or causes which induce infection by patho- genic micro-organisms ; when a tissue or surface has been rendered germ-free it is said to be in an aseptic condition. By antisej)sis is meant the means by which the septic state is combated or the aseptic state is attained. Under the aseptic condition repair of tissues takes place normally without interference, wounds and injuries heal with a minimum of dis- turbance, and the inflammatory concomitant is of the simple traumatic type, without suppuration or tendency to difl'usion. The aseptic state, in many operations in the mouth, is not readily attainable and cannot be maintained for any length of time ; but in all operations which involve the pulp and pulp chamber, as well as the periapical region through the pulp canals of teeth, strict aseptic con- ditions, as regards external infection, are perfectly attainable through exclusion of the oral secretions by means of rubber dam, the use of suitable disinfectants, and sterilized instruments. It is the class of operations here alluded to W'hich are most prolific of disturbance from infective inflammations caused by ignorant or careless manipulation. The time is at hand, if indeed it has not already arrived, when puru- lent inflammations following dental treatment will be regarded with the same condemnation of the dentist as of the general surgeon. The operative section of this work is Avritten in full recognition of the prin- ciples here indicated. OPERATIVE DENTISTRY. CHAPTER I. MACROSCOPIC ANATOMY OF THE HUMAN TEETH. By Alton Howaed Thompson, D. D. S. 1. Definition. — The teeth may be properly defined as hard, cal- careous bodies situated in that portion of the alimentary canal near the anterior or oral extremity. In man they are confined to the oral cavity and are supported by the maxillary bones only. In the lower verte- brates they may be scattered over all of the bones and cartilages sur- rounding the mouth. 2. Function. — The main function of the teeth is the mechanical sub- division of substances used for food, preparatory to their digestion ; these organs therefore belong to the alimentary system. The elements of their function are prehension, incising, crushing, mastication, and insali- vation. For the performance of these various offices, different forms of teeth are found in the denture of man. In lower animals food-habit induces the evolution of many various and extreme forms of the teeth. The secondary offices of the teeth in man are as adjuncts in vocal- ization and articulate speech ; they also bear an esthetic relation to the mouth and face. Fig. 1. Thu formation of single teeth from the single cone and its reijutition in cuniiilex teeth. 3. Mechanical Design. — All tooth forms are evolved by modification from a simple cone, which is the primitive, typal form. The teeth of fi.^hes and reptiles are but simple cones, and those of higher mammals are modifications of the single cone or combinations of two or more cones 2 17 18 MACROSCOPIC ANATOMY OF THE HUMAN TEETH. fused together. Thus in man the incisors are tbrmed of a single cone, the truncated apex of which is compressed to form tlie wide cutting- edge (Fig. 1, a). The canine or cuspid is a single cone, the apex of which is com- pressed into a trihedral point, or pointed pyramid (6). The bicuspids are composed of two cones fused together, the forms of the cones being quite distinct the entire length of the tooth, as in the upper bicuspids (c). The typal upper molar is formed by the addition of the third cone to the bicuspid form, as plainly noticed in the three roots and the primitive three cusps (d). The usual quadricuspid form is made l)y the addition of a cingule. The lower molars consist of four cones, which may be plainly distinguished by an analysis of its elements (e). Each cone in the structure of a tooth is surmounted by a cusp or tubercle. Extra cusps above the number of primary cones are but cingules or undeveloped cusps. In the genesis of tooth forms, therefore, the complex teeth, as the bicuspids and molars, are formed by the repetition and addition of cones and their accompanying cusps, both laterally and longitudinally of the jaw. 4. The Dental Arch. — The teeth of man are arranged around the margins of the upper and lower jaws in close contact, and have no Fig. 2. Square. Round Square. Round. Round V. The main types of the dental arch. interspaces between them. The basal arch is a graceful parabolic curve, with some variations which lead from the round arch to the incomplete l)arallelogram or even to a well-defined V shape. These variations may be classified as follows : First: The square arch (Fig. 2, «), This is found usually in persons of strong osseous organization, of Scotch or Irish descent — /. c. of Gaelic extraction — and is probably derived in the first instance from a dolichocephalic people. The squareness is more or less dependent upon the prominence of the large cuspids, which stand out very markedly at the angles of the square. The incisors present a flat front and project slightly, with little or no curve of the incisive line. The bicuspids and molars fall backward from the cuspids with no per- ceptible curve. The two sides are quite parallel, but sometimes there may be a slight divergence toward the cheek at the rear. This is the low form of arch which appears in the apes and some low races. THE OCCLUSION OF THE TEETH 19 Second : The round square (Fig. 2, b). This is the medium arch and is the form usually met with in ordinary, well-developed, ro- bust Americans. The cuspids seem to be only so prominent as to give character to the arch without a resemblance to the arches of the lower animals.' The incisors are vertical and the line curves slightly from one cuspid to the other. The bicuspid-and-molar line curves slightly outward from the cuspid and converges at the rear. Third : The round arch (Fig. 2, c). This is the circular or " horse-shoe " arch. It is nearly semicircular, the ends curving in- ward at the rear, the outlines of the arch tracing a decided horse-shoe shape. The cuspids are reduced to the level of the arch so that there is no prominence of these teeth. The bicuspids and molars follow the line of the curve. This arch is quite characteristic in some races, as the brachycephalic South Germans. Fourth : The round V (Fig. 2, d). In this form the round arch is constricted in front or narrowed so that the incisors mark a small curve whose apex is the centre. It is the arch of beauty and is that most admired in women of the Latin races. These are but the basal forms of the dental arch. Ordinarily, mod- ifications of these types occur in all degrees ; it is the variations, the composites, which are most met with. 5. The Occlusion of the Teeth. — The upper teeth describe the seg- ment of a circle larger than that of the lower teeth ; so that the edges of the anterior teeth above close over those below, and the buccal cusps of the grinding teeth above close outside of the buccal cusps of the lower teeth (Fig. 3). By this arrangement the buccal cusps of the lower grinders are received into the de- pressions or sulci between the buccal and lingual rows of the cusps and tubercles of the superior molars and bicuspids, and the lingual cusps of the upper grinders are received into the sulci of the lower grinders. By this arrangement the whole of the morsal surfaces of these teeth are brought into contact in the several move- ments of mastication, thereby rendering the performance of this function more effective. Then, again, the upper incisors usually close over the lower for one-third of their length. This allows of the shearing action by wdiich the incisive func- tion is performed as the edges of these teeth are drawn past each other. The line of the horizon of occlusion (Fig. 4, A-B) presents a decided Incisors. Fig. 3. Bicuspids. Molar The relative position of the upper and lower teeth in occlusion. 20 MACROSCOPIC AXATOMV OF THE HUMAN TEETH curve from front to rear, of greater or less degree in different forms of the arch. Thus it is high at the incisors, curving downward at the bicus- pids, reaching its lowest point at the first molar ; it curves upward rap- idly at the second molar, and is highest, again, at the third. In the round arch the plane is more flattened and exhibits the extreme Fig. 4. The horizon nf the line of occlusion and phane of occlusion. downward curve in the square arch. Between these extremes there is of course every variety of modification. The form of the plane of occlusion is shown in Fig. 4, C. Fig. 5. The apposition of the upper and lower teeth. The tendency of the bolus of food is toward the lowest i>art of the curve at the region of the lower first molar, so that the extraction of this tooth always affects the performance of mastication. In the apposition of the teeth of the opposite jaws the mechanical THE OCCLUSION OF THE TEETH. 21 arrangement is such that the dynamics of mastication is subserved and the greatest effectiveness secured (Fig. 5). Thus the morsal sur- face of the upper central incisor is opposed to all of that of the cen- tral incisor below and to the mesial half of the lateral ; the upper lat- eral opposes the distal half of the lateral below and the mesial face of the cuspid ; the upper cuspid, the distal half of the face of the lower cuspid and the mesial half of the first bicuspid ; the upper first bicuspid opposes the distal half of the lower first bicuspid and the mesial half of the second ; the upper second bicuspid opposes the distal half of the lower second bicuspid and part of the lower first molar : the upper first molar opposes the distal part of the lower first molar and the me- sial half of the second ; the upper second molar opposes the distal half of the lower second and part of the third ; and the upper third covers the remainder of the lower third molar. By this method of apposition the teeth are so arranged that two teeth receive the impact of half of two of the opposite jaw, thus distributing the force of occlusion and ensuring the safety and strength of the teeth. This " break-joint " arrangement permits each tooth to bear two opposing ones, and also helps to preserve the alignment. Fig. 6. Incisors. Canines or Premolars or Molars. cuspids. Bicuspids. The classes of the teeth, comprising the left half of a full denture. Then again, if one tooth be lost, the opposing teeth still rest against two teeth, one at each side of the space. The normal condition of the articulation is rarely preserved, however, as mutilation usually dis- turbs it ; the teeth move on account of the force of occlusion, and effec- tive mastication is more or less destroyed. 22 MACROSCOPIC ANATOMY OF THE HUMAX TEETH. 6. Number and Classes of the Teeth. — ]\Ian has tliirtv-two teeth, divided into four classes, viz. — (1st) incisors, (2d) canines or cuspids, (3d) PREMOLARS or BICUSPIDS, and (4th) molars (Fig. 6). This is expressed by the dental formula as follows : . 2-2 1—1 ;. 2—2 3 — 3 ^o I. , c. , oi, , m. = 32. 2-2' 1 — 1' 2 — 2' 3 — 3 (1) The incisors are eight in number, four above and four below, — two on each side of the median line. The two next to the median line are called the central ineisors, the ones next to them distally, the lat- eral incisors. (2) The cuspids are four in number, two above and two below, — one on each side immediately approximating the lateral incisor on the distal side. (3) The bicuspids are eight in number, four above and four l>elow, — two on each side approximating the cuspids on the distal side. The first of these next the cuspid is called the first bicuspid, the one next to it on the distal side the second bicuspid. The same designa- tion applies to both upper and lower bicuspids. (4) The molars are twelve in number, three on each side of each jaw, approximating the second bicusi)id on the distal side. The molar next to the second bicuspid, both above and below, is called the first molar ; the next one distally is called the second molar ; the next one distally, and the last tooth in the jaw, is called the third molar or " wisdom tooth " (dens sapientiu). Functionally, the incisors are formed for cutting, as their name im- plies ; the cuspids for prehension and tearing (for which purpose this tooth in lower animal forms is often excessively developed). It also serves in guiding the l)ite. The bicuspids are the crushing teeth, and the molars are formed for grinding, triturating and insalivating the food. The Incisors. 7. The Upper Central Incisor. — This is the first tooth in the den- tal series in man. It is situated in the front of the mouth, next to the centre of the arch, which is the mesial border of the intermaxillary bone. In adult man these bones fuse with the anterior borders of the right and left su])erior maxillary bones. Their junction with each other marks the centre of the dental arch. The (jeneral form is that of a truncated cone with its top flattened out to form the cutting edge. Its function is to cut or incise food, hence its name from the Lat. incisus, " to cut into." THE INCISORS. 23 The mechanical structure of the crown is a matter of importance. It will be observed that it consists of several elements : first, a broad cut- ting blade (Fig. 7, a) supported by two strong lateral columns (6) on each side, and that these columns are upheld by two strong marginal Fig. 8. .Fig. 7. The mechanical design of the crown of the upper central incisor : a, the blade ; 6, the two columns supporting the blade ; c, the marginal ridges acting as guys, brac- ing the columns ; cl, the basal ridge as the base of attachment for the guys. cl f Diagram of the labial face of the upper central incisor. ridges (c) leading up from the lower ridge (d). These ridges are but- tresses, which guy and uphold the columns which contain and carry the blade. Hence, when these ridges are destroyed by caries or in operating, the support of the column is lost and the blade readily breaks away. The form of the crown is spade-like, or a compressed-wedge shape, the edge being quite thin and the thickness increasing rapidly to the base. It is slightly bent toward the lingual side, or much curled over in some cases. The labial face is imperfectly square or oblong, the cervical margin being rounded (Fig, 8, a). It is convex from side to side, but only slightly so from cervix to edge. Two shallow depressions or furrows extend the length of the face perpendicularly (6) dividing it into thirds, called lobes, — the mesial, (e), median (d) and distal lobes (e). These furrows and lobes are quite conspicuous when the tooth is erupted, but are abraded by age and the Avear of use and denti- frices, until the face becomes smooth. The mesial margin is a little longer than the distal so that the cutting edge slopes upward toward the distal side (/). The lingual face is smaller than the labial, being on the inner and smaller curve of the crown, and is narrower from side to side (Fig. 9). It is triangular in outline, being wide at the edge and narrow and rounded at the base or cervix. The marginal ridges («) are high and conspicuous, and extend from the basal ridge to the edge on the Diagram of the lingual face of the upper central in- cisor. 24 MACROSCOPIC ANATOMY OF THE HUMAN TEETH mesial and distal margins of this surface. The basal ridge (6) is a strong elevation continuous with the marginal ridges at the base of the crown. It is sometimes developed into a raised cusp, the ridge at the base of which forms a cingulum. A ridge x)r lobe (c) extends from the basal ridge to the centre of the edge, uniting with the median lobe from the labial face to form the median tubercle. A depression or fossa {) which sometimes extends The mesial and distal faces and iii)ward OU the I'OOt. The poiut of COUtact edge of the upper central in- . i i • i . i cisor. With the opposing tooth is near the cutting edge. The distal face is also triangular in outline (Fig. 10) but it is more curved in the longitudinal axis, so that this surface is convex in all directions. It is most curved in the transverse direction. The enamel dips downward into the surface (d), as in the mesial, but there is not so much of a depression above this line. The point of contact is one-third of the distance from the angle (e). The edr/e, or morsal margin, of the crown is formed by the com- pression of the top of the truncated primitive cone. It is quite wide and square except at the distal corner, which is rounded. The angle with the mesial face is acute (Fig. 10, /). When the tooth is first erupted, the edge has three ]irominent tubercles (r/), which correspond to the ridges on the labial and lingual faces. These are soon Avorn off with use, so that the edge usually looks straight. The pitch of the edge is toward the median line. The neck of the central incisor is a rounded pear-shape in outline, the labial half being wider (Fig. 11, «) than the lingual. There is not much constriction of the tooth at the neck. The enamel edge curves upward on the root on the labial and lingual sides, and dips down- ward on the mesial and distal faces. It terminates aliruptly on all sides, especially on the lingual, where a considerable ridge is some- times raised (Fig. 10, c). THE INCISORS. 25 Fig. 11. The root of the upper cen- tral incisor. The root is cone-shaped and tapering (Fig. 11, h). The ronnded pear-shaped section continues ahnost to the end. The pi(^p chamber is spacious and open, and of the general form of the tooth (a and e). The radi- cal portion of the canal gives free access, but the flattened coronal portion is difficult to cleanse. In young teeth the cornua or horns of the pnlp may project far toward the angles (e). 8. The Lateral Incisor. — This tooth approxi- mates the central incisor on its distal side, and is also implanted in the intermaxillary bone. It is of similar spade-like form and of the same architectural design as the central, modified by the distal half being more rounded in every direc- tion. As the crown is narrower than the central, the destruction of the marginal ridges on the lingual face weakens the edge still more, so that it breaks off more easily. The crown is narrower in the mesio- distal diameter than the central, but, still almost as wide labio-lingually, the relative difference of thickness in the two directions is more ap- parent. The tooth has the appearance of being compressed mesio- distally. The thickness increases rapidly from the edge to the neck (Fig. 12, B). Fig. 12. ^^^■^ B C D The upper lateral incisor. The labial face (Fig. 12, C) is more rounded than that of the cen- tral. It is half incisor and half cuspid («), the mesial half toward the central incisor resembling that tooth (6), and the distal half tow'ard the cuspid resembling it (c). The mesial angle of the edge is quite acute, while the distal angle is rounded and obtuse. The three lobes may be well developed, similar to those on the central incisor, but are usually indistinct, although the central ridge is prominent. The lingual face (Fig. 12, D) is much depressed, but less concave than that of the central incisor. The marginal {d) and basal ridges {e) are quite prominent. The basal ridge is often raised into a prominent cingule or talon, an exaggerated example of which is sliown in Fig. 13, w^hich is a revival of the basal talon found in the apes, — and the insectivora. This cingule occurs more frequently on the lateral 26 MACROSCOPIC ANATOMY OF THE HUMAN TEETH. incisor than on any other of tlie anterior teeth. The de})ression above it is often the location of a fault, a fissure or pit, which be- comes the seat of caries. The basal ridge is f^fG- 13. . .1111. sometimes cut by a fissure which leads down quite upon the neck of the tooth (Fig. 12,/). Sometimes the entire surface is full and rounded without any concavity whatever. The mesial face (g) is of triangular form similar 5f to that of the central incisor. It is rounded toward the edge labio-lingually, but flattened at the neck, '^ with a depression at the enamel line which leads Showing unusual develop- mi i i • i i • ment of the cinguie or Upward upou the root. ilie labial angle is some- basal talon on an incisor, ^j^^^^^g ^^le Seat of a dcprCSsioU (h), which givCS the (From case reported by Dr. a v /? & w. H. Mitchell, Dental Cos- angle a Iiook shapc. The depression varies in wifAs^o . xxxiv.p. o .) ^vij^ji jii^j depth and may become the seat of caries. The point of contact with the central incisor is at the junction of the lower with the middle third of the length of the face. The distal face is more convex in all directions and resembles the cuspid in form, in harmony with the general form of the distal half of that tooth. From cervix to edge it is rounded and the contact emi- nence in the middle third is very full (/). From this point it rounds off rapidly to the edge. The upper third is depressed rapidly toward the cervix, with a considerable depression at the enamel line leading off to the distal groove on the root. The edge is divided into two portions by the prominent tubercle (j) in the middle which terminates the prominent central ridge of the labial face. The mesial half is straight, like that of the central. When w^orn, these features disappear and the edge becomes almost straight. The pitch of the edge, like that of the central, is toward the median line. The neck is much flattened mesio-distally, and is of a compressed pear shape, or flattened oval on section. The enamel margin pursues tlie same course as on the central incisor, rounding upward toward the root on the labial and lingual sides and dip])ing downward on the distal and mesial. It does not terminate so abruptly as that of the central incisor, and presents less of a ridge at the gingival margin. The )'Ofjt is commonly longer than that of the central incisor, is narrower, flattened mesio-distally (Fig. 12, A, B). It tapers gradually, not rapidly like the root of the central incisor. It is a flattened oval on section (e). Sometimes there is a hook at the end, curved distally. Grooves sometimes occur on the mesial and distal sides. The jndp canal \s flattened in conformity to the sha])c of the root, but is readily entered if the root be straight. THE INCISORS. 27 The lateral incisor is very irregular as to form, presenting various degrees of deformity or abnormality, and may sometimes be reduced to a mere peg. It is also erratic as to eruption, being sometimes sup- pressed, not appearing for several generations of a family. It follows the third molar in the frequency of its irregularities both as to form and frequency of non-eruption. The third incisor of the primitive typal mammal sometimes reap- pears in man, and is known as a supernumerary. It rarely assumes the proper incisor form and position in the arch, but usually erupts within the arch and is a mere pointed-peg-shaped tooth. 9. The Lower Incisors. — These are most conveniently described as a group, as they are very similar in form, having but slight variations between the central and lateral incisors to be noted. They are located in the anterior portion of the lower jaw, upon each side of the median line, opposite the incisors above. Their function is the same as that of the upper incisors, the cutting of food, which they per- form by opposing the upper. The lower central opposes only the cen- tral above ; the lateral, both the upper central and lateral incisors. The lower central incisor is the smallest tooth in the dental series. It is of spade-like form (Fig. 14), the crown being a doul)le wedge shape (a, 6). The first wedge (ci) is observed on viewing the crown from the front, the widest portion being at the morsal edge and the point at the cervix. The second wedge is observed from the side (6), the widest part being at the neck and the point at the morsal edge of the crown. The edge is thin, but the labio-lingual diameter increases rapidly to the cervix, which is the . rrM • • 1 '^^^ lower incisor. Widest part. The crown is widest mesio-distally at the edge, but diminishes to the neck, which is scarcely more than half the width of the edge. The tooth cone is therefore compressed in one direction at the edge, and in another at the cervix. The mechanical elements are the same as those of the upper central, but with the parts less strongly marked. The labial face is a long wedge shape {a), the widest part at the edge and narrowing to the cervix. It is usually straight, or nearly so, longitudinally, and straight across the edge, but round and con- vex at the neck and the cervical half. Sometimes vertical ridges are found on these teeth when they are first erupted, but these soon wear off. The lingual face is depressed and concave from edge to cervix (c), but less so from side to side. The marginal ridges are often well 28 MACROSCOPIC AXATOMY^ OF THE HUMAN TEETH. marked. In the lateral incisor the fossa is often more marked and the marginal ridges more distinct. The mesial and distal sides are of wedge-like form, straight from edge to cervix and widening in the same direction. A depression runs across the neck just above the enamel line. The nech is much compressed disto-mesially, and the root partakes of this flattening through its entire length. The section presents a compressed oval {e). The enamel line dips downward on the labial and lingual sides, and curves upward on the mesial and distal, in a manner characteristic of the incisors. The edge is perfectly straight from side to side, after the three tuber- cles, found when first erupted, are worn off. The root is flattened like the neck, and frequently a groove runs the entire length on the mesial and distal sides. Occasionally complete bifurcation results, which recalls the form of this tooth found in lower animals. The pulp canal (e) is of similar form to the root, and is flattened and thin, so that it is often diflicult to effect an entrance to it with instruments. The lateral is similar in form to the central incisor, but is Mider at the edge and the distal corner of the edge is slightly rounded (d). In all other features it resembles the central incisor. The Canines or Cuspids. 10. The Upper Cuspid. — This is the third tooth from the median line and approximates the lateral incisor on its distal side. It is the first tooth posterior to the intermaxillary suture and is imbedded in the maxilla proper. It is commonly said to form the spring of the arch, and conveys the impression of great strength, as is indicated by its strong implantation. It is more strongly implanted, and by a longer and larger root, than any of the other teeth. Zoologically it is the largest tooth in the dental series, but in man is much reduced from its prototype, the larger carnassial canine of lower animals, especially the carnivora. It is the principal prehensile tooth, and is therefore first in order of function in the dental series. The canine in man preserves the typal form, for its mechanical structure is still that of a single cone, brought to a point (Fig. 15, a). This is the earliest form of teeth found in the lower verte- brates, the fishes and reptiles, which present only simple conical teeth in all parts of the jaw. It has an older history than any other tooth, and still bears the marks of the many changes through which it has passed in the course of its evolution. THE CANINES OR CUSPIDS. 29 The croion has a spear-head shape (b), hence its name, cuspid, from the Lat. ciispis, "point, pointed end." It is constructed essentially for piercing and tearing. The central cusp or point is braced in all directions ; the edges leading up to it both mesially and distally (which serve for cutting as well), the strong labial ridge coming down- FiG. 15. The upper cuspid. f g h Avard from the cervix (c) to the median ridge leading up on the lingual surface {d), all support it in the office of prehension and the laceration of flesh. The labial face (b) presents the outlines of the spear shape, more or less rounded in different cases. Starting from the well-defined cusp just in front of the central axis of the tooth, it widens sharply for about one-third of its length, whence it narrows gradually to the gum line, Avhich is fully rounded. In some cases the mesial and distal angles are rounded and the outlines are more of a leaf shape (e). The surface is slightly rounded mesio-distally, so that the sides slope roundlv or flatly away from the central ridge. This ridge descends from the middle of the cervical margin, curving slightly forward and then backward to the point of the cusp (c). This curve recalls the curving shape of this tooth in the Felidse. It is usually a sharp, prominent ridge, but may be reduced and rounded so as to he scarcely perceptible. The three lobes of the surface are imperfectly marked, — the central ridge dominating and dwarfing the lateral ones. The lateral furrows on each side of the central ridge separating it from the lateral lobes are more or less marked, especially toward the edge. Wear reduces in time the prom- inence of the lobes and ridges and obliterates the furrows. The lingual face is of similar spear shape (d), but is more flat. It is rarely concave. The thickness of the crown increases gradually to the lateral prominences, which gives a blade-like edge, then rapidly to the shoulder at the base. A strong vertical ridge extends from the cusp to the basal ridge (rf), with a slight concave depression on each side. The basal ridge is well marked and sometimes develops into a cingule, more or less marked. The marginal ridges lead up on each 30 MACROSCOPIC ANATOMY OF THE HUMAN TEETH. side only so far as the lateral protuberances. They are not strongly marked as a rule. The foss» on each side of the vertical median ridge, between it and the marginal ridges, may be quite deep but are usually shallow and ill defined. The mesial face in outline is not unlike the central incisor, but its contour is very different, for it is more or less rounded in all direc- tions, and the lateral eminence in the lesser third makes this part espe- cially full («). From this point the surface is depressed roundly to the enamel line at the neck, where a depression of greater or less depth is found. It is somewhat flattened at the cervix. The point of contact is at the eminence, which touches the lateral incisor. The distal face is of similar form to the mesial, except that it is more full and the eminence more pronounced, which gives the increased width of the crown on that side. The surface descends ra])idly toward the neck and is rounded labio-lingually. The point of contact with the first bi- cuspid is on the lateral protuberance. The morsal edge presents a prominent cusp which is almost central to the long axis of the tooth. The side facets slope away, but still retain their cutting edge (b). The distal side of the edge is longer than the mesial, by reason of the increased size of the distal protuberant angle. The sharp point is soon worn off to a rounded cusp, and, as wear increases with age, it may be reduced to a straight surface between the mesial and distal protuberances (g). The neck is a flattened oval on section, or the lateral direction of the labial portion may be greater than that of the lingual (/;). The enamel line preserves the same curves as on the incisors, /. e. rounding upward on the labial and lingual surfaces and dipping downward on the mesial and distal. The enamel terminates gradually with l)ut a slight ridge, unless it should be on the lingual side. A depression occurs on both mesial and distal sides al)ove the curve, which may lead up as a groove on the root. The root is longer than that of any other tooth, and it is at least one-third larger than that of the central incisor. It is of a rounded trihedral form, or irregularly conical. It is usually straight, and tajiers to a slender point, which may be curved or very crooked. In well- arranged dentures, where it has erupted naturally, it is usually straight. The pulp canal is large and open, of the same form as the tooth, and easily entered. It is regularly formed exce])t in those cases where the root is curved, and even in these it can be filled if not too crooked, a» it is so o]»en and accessible. 11. The Lower Cuspid. — This is similar to the upper in form and outline, except that it is somewhat smaller, more slender, and more rounded in form (Fig. 16, a). It differs also in being more compressed THE CANINES OR CUSPIDS. 31 mesio-clistally and in being flattened in the neck and root. The crown leans backward on the root so that the mesial face is almost straight the entire length of root and crown. It forms the spring of the lower arch, and is strongly built to oppose the strong upper cuspid in the act of prehension and tearing. It opposes the mesial surface of the cuspid above and the distal surface of the upper lateral incisor. Fig. Ifi. The lower cuspid. The labial face is a long oval {a), the cusp being blunt and the neck rounded while the mesial side (c) is flattened. The lobes are indistinct and the central ridge rounded from side to side. The entire face is in- clined inward to accommodate the occlusion. The crown in many cases presents the appearance of being blunt toward the distal side. The lingual face (h) is flat, sometimes cup-shaped, and the marginal ridges are not prominent. The central ridge sometimes stands out strongly. The basal ridge is weak and is rarely developed into a cingule. The crown increases gradually in thickness from the point to the neck. The morsal surface presents a mere rounded eminence ; the cusp may be sharp in childhood, but usually it is soon reduced by wear. Some- times it remains sharp and prominent. The lateral edges are not devel- oped, but are mere ridges leading down to the lateral faces, which are not prominent, except the distal (f/), which is often full. The mesial face is quite flat, and straight with that face of the root. The eminence is not marked. It is rounded only at the eminence, but flattened at the cervical third (c). The distal face has the most prominent eminence {(J), the crown being bent in that direction. The cervical third of this face is flat. It descends rapidly from the eminence. The nech is usually oval (/) or, when compressed, spindle-shaped upon section (g), being depressed on the mesial and distal sides, at the origin of the grooves running up on the root. The enamel line is not so variable as on the incisor, but more nearly on a level on all four aspects. 32 MACROSCOPIC ANATOMY OF THE HUMAN TEETH. The root is long, flattened, and ta})ering [a, b, c). It is shorter than that of the upper euspid. It is grooved on the mesial and distal sides, — so much so as to tend toward bifurcation. This, indeed, sometimes hap- j)ens in man, thereby recalling the form usual to the primates and some other lower animals. The jj»//9 canal is of the same general form as the root, often pre- senting the spindle-shape on section. It is somewhat difficult to enter on account of its flattened shape and narrowed channel. Fig. 17. Tlie upper bicuspids. ment of a root to support it. The Bicuspids. 1 2. The Upper Bicuspids. — The upper Ijicuspid is formed by duplica- tion of the primitive cone and cusp in a transverse direction (Fig. 17, a). Viewed from the standpoint of com- parative dental anatomy, the external cone is the canine cone — and to this is added the internal or hicnxpul cone, the tooth being a double canine. The bi- cuspids are the first of the complex teeth. The internal cusp is formed by the raising of the inner primitive cusp of the cuspid and the develop- The distinctive feature of the architec- ture, therefore, is its formation from two cones, and this makes it a weak tooth as regards its mechanical structure and resistance to mas- tication, for the binding of the bases of the cones and cusps depends upon the connecting power of the two marginal ridges {b, b), and when these are destroyed the cones readily part and split ofl". The ])icuspids in man are homologous with the j)remolars of the (juadrumana and other lower mammals. They succeed and dis]>lace the molars or grinders of the deciduous set. They are placed next after the cuspids in both jaws, and midway between the cutting and ginnding teeth. Their function is the ciHishing of food preparatory to mastication. The upper first bicuspid apj)roximates the cuspid on the distal side. The buccal face (c) is of spear-head shape, similar to that of the cus])id. This is more apparent in some lower mammals than in man, in whom it is much reduced and rounded, so as to give usually the ap])ear- ance of a long, rounded oval. The buccal cusp (c) rises sharj)ly and prominently from the lower centre of the face, from which a strong ridge { on to the neck, especially upon the buccal side. The enamel line is quite irregular, dipping down on the lingual and buccal, and leading well up on the mesial and distal sides. The roots are two in number, placed with their longer diameter trans- versely to the jaw. They are wide bucco-lingually, and flat and narrow disto-mesially, being situated distally and mcsially to tlie crown. The posterior is formed of the two posterior cones, and the anterior of the two anterior cones (A). This is plainly shown in the formation of the roots, which are grooved both distally and mesially, and in the tendency to bifurcation, which sometimes actually occurs. They divide close to the crown, so that the grooves of bifurcation extend well up on the neck. The distal root is thicker and more rounded than the mesial, the latter being more flattened, with the grooves deeper, and it is more often bifurcated. Both are deflected from the median line. The pi'lp canal is shaped like the roots, with two main branches. The distal branch is the larger, being round and open, as the root is more rounded. The mesial branch is flat and spindle-shaped, being difficult to enter, and usually having two sub-branches following the buccal and lingual divisions of the root. These sub-branches are small and hair- like and troublesome to enter. The lower second molar (Fig. 25) differs from the first in many respects. It is of the same general form, but is more quadrangular, as it has but four tubercles. It is more rounded and symmetrical than the first, the four cones and four primitive tubercles being well marked. The absence of the fifth tubercle leads to most of the differences between the second and the first molar. The morsal face (c) has but four tubercles, one at each corner of the face, difft'ring from that of the first molar, whicli lias five. The fifth tubercle rarely appears in the higher races of maidvind, but is some- times found in tlie low and savage races, and occurs regularly in the apes. It is not uncommon in the negro, but is absent as a rule in THE MOLARS. 45 the European races. The tubercles are symmetrical, rounded and obtuse, the lingual being, however, sharper than the buccal. The sulci describe a cruciform shape, separating the four tubercles symmetrically from each other. The buccal groove sometimes continues on to the buccal face, rarely to the lingual. The triangular grooves run up on the morsal triangular ridges. The marginal ridges are well marked, the mesial and distal being often divided by grooves. The triangular ridges are usually well marked, leading to the centre of the tooth. They are full and strong. The buccal face (d) is convex and of more regular form than that of the first molar. It is divided into two lobes (e, e) by the Ijuccal Fig. 25. h h The lower second molar. groove (d), which is rarely deep. A pit is often found in the centre of the face, which may become the seat of caries. The face is curved toward the centre of the tooth, as in the first molar. The lingual face is similar to that of the first molar, but may be more rounded toward the morsal border. It is symmetrically convex in both directions. The mesial and distal faces (/) are similar to those of the first molar except that, the crown being smaller, they may be more perpendicular, but are well rounded. The 7ieck (g) is more regularly formed than that of the first molar, the margin of the enamel line being quite as irregular. It may be more constricted. The roots (h, h) are similar to those of the first molar, but are more rounded in shape, are usually crooked, and on that account difficult to treat. The pulp canals are similar to those of the first molar, but the tend- ency to crookedness renders treatment quite difficult. The direction of irregularity of form is so uncertain that no rule can be ap})lied to it. 17. The Third Molars. — The upper and lower third molars can best ■be described together, on account of their similar eccentricities. They are very irregular as to the time and to the frecpiency of their appearance in civilized man. About one-half of the individuals of Euroi)ean races 46 MACROSCOPIC AXATOMY OF THE HUMAN TEETH. erupt them at the normal period, /. e. seventeen to twenty-one years of age. In one-fourth they erupt at irregular intervals to the thirtieth vear, and in the remainder they may appear later, or the first, seeond, third, or all of them, may be absent altogether. In one series of forty adult skulls observed, twelve had one or more absent. The absence and other erratic peculiarities of these teeth sometimes seem to be hereditary and can be traced in families through several generations. This tooth is often reduced in size and may be a mere peg (Fig. 26, a). It is of very irregular form in civilized races, but is as large and as Avell formed as the other molars in most races low in the ethnological scale. The contraction of the jaws through disuse has much to do with the mal- development of this tooth, and it is , ,». V ™ often so cramped for room as to pro- duce distressing irritation which ne- The upi)er third molar. . . ' cessitates its removal. Impaction and malposition of the third molars render them difficult of extraction and are the fruitful source of many serious lesions. (See the chapter on Extraction of Teeth.) The upper third molar is more or less similar to the other upper molars when perfect and well developed, but it is very erratic as to form and structure. This tooth, when well formed, is of trituberculate form (b), the disto-lingual cingule being suppressed. This cingule diminislies grad- ually from the first molar, in which it is well formed, to the second, where it is reduced, then to the third, where it is almost or entirely absent. The obli(|ue ridge thus becomes the posterior marginal ridge (c), as in the typical trituberculate molar. The three tubercles are reduced and rounded. The sulci usually degenerate into fissures, as the formation of this tooth is notoriously faulty. The enlarged mesial fissures thus become the seat of extensive caries. The buccal face resembles that of the first and second molars, but is more rounded. The lingual face (d) is full and rounded, with but a single lobe, owing to the reduction or absence of the disto-lingual tubercle. The mesial face (e) is similar to that of the seeond molar, but reduced, and the distal face is round and short, as no tooth succeeds it in the rear. The neck is constricted and tapers toward the conate roots. It is of a rather rounded triangular shape. The three roofs of the upper molars are, in the third, usually more blunt, conate, short in form, and may curve backward. In lower races and sometimes in individuals having strong osseous organizations, the THE MOLARS. 47 The lower third molar. typical three molar roots are found. Sometimes there are multiple roots, which are likely to be curved in various directions and may have decided hooks. In the large conate root, the pulp canals usually coalesce, but in cases in which the root is divided there will also be division of the pulp chamber. The lower third molar is similar to the other lower molars in general form (Fig. 27, a), but is probably not so erratic and not subject to such extreme variations. The crown is quadrangular in section, the angles rounded. On the morsal face (b), there are four principal tubercles as in the second molar, but this may be supplemented by the ex- tension of the disto-marginal ridge into a cingule or heel (e). This heel is rather erratic ; it may be large or small, thus modifying the size of the morsal sur- face. Sometimes the face is wrinkled and, like this tooth in the orang utan, the sulci exhibit the cruciform shape similar to that of the second molar. The many grooves leading aw^ay from the main sulcus may be imperfect and become the seat of caries. The buccal groove running from the morsal on to the buccal face (a) is very subject to imperfection. The four lateral faces are similar to those of the second molar, except that the distal is more convex and full, and often very prominent if the fifth cingule is well developed. The neck is of similar shape to that of the second molar. The roots are similar to those of the other lower molars, but generally smaller as compared with the crown (d). They are usually divided like the others, but the two may be fused together, or be closely opposed. In either case they are usually projected distally more or less, leading backward into and under the ramus, thereby rendering extraction of this tooth difficult and dangerous, especially where the maxilla is of Fig. 28. The fourth molar. dense structure or where there is impaction. The roots are usually more rounded, especially the distal one, than those of the other molars. The pulp canals are generally divided, whether the root is or not. 48 MACROSCOPIC ANATOMY OF THE HUMAN TEETH. As the roots are usually crooked, the difficulty of euterins: them is increased as the canals follow the form of the roots. Fourth molars sometimes appear as supernumerary teeth, and are either fused to the up})er third molar in a yariety of uncouth forms (Fig. 28, a) or erupt separately as mere peg-shaped teeth bet\yeen the buccal faces of the second and third molars (6) or at the distal aspect of the latter tooth. The fourth molar rarely apjiears as a full molar, except in some of the large-toothed races, as negroes, Australians, etc., and then usually in the \o\\ev jaw. Among the negroes in Africa the fourth molar is sometimes found in full form as a typical molar. The Deciduous Teeth. The DECIDUOUS teeth are those which appear in infancy and serye the purpose of dental organs during the first years of the development of the individual, until the jaws and their environment are ready for the larger, permanent teeth to come into place. They bear a direct relationship to the conditions of the digestive apparatus and the food required at that early stage. The food of infancy being simple and requiring little mastication, the deciduous set are small and insufficient for the reduction of more resisting substances. As these foods come to form })art of the dietary, the larger teeth of the permanent set appear, and perform the duties of higher functional activity. The crowns of the deciduous teeth resemble, in a general way, those of the permanent teeth which succeed them, except the deciduous molars (Fig. 29, «, d), which are very diffi:'rent from the bicuspids of the permanent set which displace them. Fig. 29. Tilt' deciduous teeth. The incisors of ])()th jaws precede the analogous teeth of the same series of the permanent set. They are similar in form, l)ut reduced (6), THE DECIDUOUS TEETH. 49 and do not have the main features so characteristically marked. They are infantile in form and function. The roots of these teeth are resorbed at from the fifth to the ninth year, when the permanent incisors come into place, beginning with the lower centrals. The cuspids (c) of both jaws are still more reduced from the strong, full form of their permanent successors, and are but little more specialized than the incisors. They are of the same general form as the permanent cuspids, but much less developed. But in the deciduous molars are found some important features which mark distinctive differences. They are of true molar form as compared with the permanent molars, but they occupy the place of the bicuspids. There are no bicuspids in the deciduous set, the molars being of full molar pattern {a, d). The deciduous molars of both jaws are of irregular, quadrangular form on the morsal surface, diverging rapidly outward to the neck, which presents a large buccal ridge standing out at the margin of the enamel, and is rounded off suddenly to the neck, which is much con- tracted. This thick ridge is characteristic of the deciduous molars and is absent in those of the permanent denture. It is somewhat more prominent and bulging on the buccal than on the other faces. In adjusting ferrule crowns to these teeth, the gold need not be carried beyond this ridge but burnished over it slightly. The morsal surface (e) of the upper deciduous grinders presents the characteristic pattern of the upper molars, four tubercles, oblique ridges, etc., but reduced and contracted. A distinctive feature is that the marginal ridges and angles are more acute and sharp than in the per- manent molars. Sometimes the two lingual cusps are reduced to one and the lingual border is rounded and crescentic. The second molar is larger than the first and the morsal surface is wider. The transverse diameter of the crowns of the upper molars is the longest. The LOWEE MOLARS (cI) are similar to the permanent molars in pat- tern, but are more irregular as to the contour of the morsal surface (/). The tubercles may be higher than in the upper molars, and the tri- angular ridges more marked. The central fossa may be large and wide, or divided by the triangular ridges. The second molar is five-lobed, unlike the second permanent molar, which has but four cusps. The morsal face is decidedly trapezoidal in outline, the mesio-distal diameter being greater than the transverse. The roots of the deciduous molars are similar to those of the other molars, except that they are very divergent to accommodate the crown of the advancing bicuspids. They are thin and long, and difficult to 4 50 MACROSCOPIC ANATOMY OF THE HUMAN TEETH. enter and fill. The pulp chamber is large and open in the crown ; as a consequence of this caries soon reaches the pulp. Treatment and filling of the canals is difficult and uncertain. The Variations of Tooth Forms. 19. The teeth may vary quite extensively from the typal forms which have been described, and these variations may he due to a number of causes. Through all degrees of variation, however, the type is still pre- served, unless the tooth form is quite destroyed by pathological causes. The general causes of variation may be enumerated as follows : (1) Incompleteness of development. (2) Reversion to primitive types. (3) Temperamental impress. (4) Pathological lesions. (1) Under incompleteness of development may be grouped all those varieties of stunted growth which are the eifect of disuse and the consequent effort of Nature to reduce and suppress the teeth as useless parts. The third molar teeth suffer most from these suppressive attempts of Nature in the eifort toward economy of growth ; next to these teeth, the upper lateral incisors are most frequently aifected by reduction of size, stunted growth and suppression. Other teeth are rarely aifected, or but very slightly, by this influence, except in rare cases. (2) Under the second head, reversion to primitive types, we have a variety of interesting phenomena in the form of parts of the human teeth which seem to be a zoological legacy. These are conspicuous feat- ures which reappear and seem to recall the form of the teeth in loAver animal orders, especially of the quadrumana and insectivora. Among these features may be mentioned the curved upper central incisor with the prominent cingule on the lingual buccal ridge, making a notch which recalls the incisors of tlie moles ; the prominent cingule on the lingual face of the lateral incisor, which is not uncommon and recalls the form found in the insectivora and some of the quadrumana ; the extra-long, curved cuspid, with extra-large median ridges, which recalls the large forms of this tooth in the baboons and in the car- nivora ; the double root sometimes found in this tooth is also a re- version to the insectivorous type ; the three-rooted bicuspid is a quad- rumanous reversion ; the upper tricuspid molar is a primitive typal form, leading back to the lemurs and beyond them to the early typal mammals fijund in fossil formations ; the notched and grooved incisor recalls the divided incisor of the Galeopithecus ; the double-rooted loAver incisors and cuspids recall insectivorous forms ; the unicuspid lower first bicuspid is an insectivorous type and is often quite marked in man ; THE VARIATIONS OF TOOTH FORMS. 51 the fifth cusp on the lower second molar is a quadrumanous rever- sion ; the wrinkled surface of the lower third molar is like that of the orang. There are other features that might be named illustrating the work- ings of the law of atavism, by which parts once lost in evolution may reappear and be reproduced. (3) Under the third head, temperamental impress, may be noticed those differences of form and structure which have relation to the domi- nant temperament in the constitution of the individual. Great differ- ences exist between the teeth of different persons, and these are mainly dictated by temperament. The teeth of the jyrimary basal temperaments present the following physical peculiarities, which are characteristic of the particular tempera- ment : The BILIOUS TEMPERAMENT presents teeth that are of a strong yellow ; large, long, and angular, often with transverse lines of forma- tion, without brilliancy, transparency, and of but slight translucency ; firm and close set and well locked in articulation. The SAXGUIXE TEMPERAMEXT has teeth that are symmetrical and well proportioned, with curved or rounded outlines, and round cusps ; cream color, inclined to yellow, rather brilliant and translucent ; well set, and occlusion firm. The NERVOUS TEMPERAMENT has teeth which are rather loner, the cutting edges and cusps long and fine ; color pearl-blue or gray, very transparent at the apex ; the occlusion very penetrating. The LYMPHATIC TEMPERAMENT prcscuts teeth that are pallid or opaque, dull or muddy in coloring ; large, broad, ill-shaped, cusps low and rounded ; the occlusion lose and flat. Of the binary combinations : The SAXGUix^EO-BiLious has teeth which are large, M^ith strong edges and large cusps ; color dark yellow, and quality good. The XERVO-BiLious has teeth that are long and narrow, with long cusps ; color yellowish or bluish or both combined ; the enamel strong, the dentin soft. The LYMPHO-BiLious has teeth that are large, with thick edges and short thick cusps ; yellowish in color ; enamel of good structure and polish, and dentin fair. The BiLio-SAXGUiXEOUS has teeth of average size, round arch, well- developed cusps and edges ; rich dark -cream color ; excellent in quality. The NERVO-SANGUINEOUS has teeth of average size, good shape, round arch, good edges and cusps ; rich cream color ; enamel and dentin of excellent structure. The LYMPHO-SANGUINEOUS has teeth of more than average size, 52 MACROSCOPIC ANATOMY OF THE HUMAX TEETH. shapely edges and cusps, rounded arch ; color grayish cream ; enamel and dentin fairly good. The BiLio-NERVOus has teeth variable in size and form, sometimes broad, again very long with more pointed and long cusps ; the color generallv bluish ; enamel fairly good, dentin soft and sensitive. The SANGUINEO-XEEVOUS has teeth of average size, good shape, round arch ; color grayish blue ; soft and frail. The BiLio-LYMPHATic luis teeth usually large, with thick edges, short thick cusps, and flat arch ; color yellowish ; quality good. The SANGUiNEO-LYMPHATic has teeth of more than the average size, broad round arch ; color gray ; enamel and dentin poor. The XEEVf)-LYMPHATic has teeth of average size, good shape, aver- age length, rather round arch ; color bluish gray ; soft and poor. Combinations of the binary temperaments are of the most common occurrence in individuals, but there is usually one basal temperament that preponderates over the others and gives its characteristic to the teeth as a predominating influence. (4) Under the fourth head, patholog-ical lesions, are to be included all those disturbances of nutrition which eventuate in faulty formation of the teeth, whether due to specific hereditary diseases, mere malnutri- tion, idiosyncrasies, predispositions, defective functional life, etc. But this leads beyond the province of this chapter into the field of special pathology. CHAPTER IL THE EMBRYOLOGY AND HISTOLOGY OF THE DENTAL TISSUES. By R. R. Andrews, A. M., D. D. S. A CLEAR understanding of the histology of the teeth can only be had through a study of the complex processes through which the tissue elements have had their origin or have derived their forms. The teeth do not belong to the bony skeleton of the body, but, like the hair, nails, etc., are parts of the dermal system. The origin of the tissues of the teeth is from two of the three germinal layers of the blastoderm, the epiblastic and mesoblastic layers. A transverse section through the blastoderm of a chick shows that the epiblast, or outer layer, is formed of cells like columnar epithelium ; their shape is probably due to lateral pressure of adjoining cells. It is from this layer that epithelium is formed, and epithelial tissue is the origin of the enamel. The mesoblast, or middle layer, is composed of cells said to be derived from both hypoblast and epiblast, but princi- pally from the latter. They are merely nucleated structures, containing granules, the nuclei of the future cells of the connective tissues. In this state they have no cell-limit or wall ; as they grow older they accumu- late around themselves formed material. Only in maturer stages do these cells develop, on their surfaces, an optically distinct membrane or other structure. It is from the cells of the mesoblast that the em- bryonic comiective tissue which forms the dentinal papilla originates. Development of the Jaws. As stated by Prof. Sudduth,^ the first indication of the formation of the oral cavity is seen very early in the life history of the embryo. The superior maxilla arises from three separate points : on either side of the embryonic head a process springs from the first pharyngeal arch. The processes pass downward and forward, and unite with the sides of the nasal process. From the frontal prominence, the third process, the incisive, grows downward and fills in the space between the ends of the two preceding processes. By a union of these three processes the supe- rior maxillse are completed. The inferior maxilla is formed by buds growing from the first pharyngeal arch ; these buds grow rapidly until ^ American System of Dentistry, vol. i. p. 550. 53 54 EMBRYOLOGY AND HISTOLOGY OF DENTAL TISSUES. Fig. 30. — 1 '?^?3^s^ union occurs at the median line. The central portion of the arch thus formed, very soon after the union of the two lateral processes, becomes diiferentiated into a cartilaginous cord or band, which serves to strengthen the embryonic jaw. This is Meckel's cartilage. It is formed of two parts arising from the mallei of the ears and traversing both sides of the embvronic jaw to the point of union. While the jaw-bone is forming, Meckel's cartilage disappears, by absorption ; some authorities believe it becomes ossified, forming part of the inferior maxilla. The Embryonic Mucous Membrane. If at a time just previous to tooth formation a section across the lower jaw is cut, it will be found to consist of a central mass of embryonic connective - tissue cells edged on every surface by the in- nermost layer of the epithelium. This covering of epithelium is the Malpighian or mother layer, most important to the dental histologist, because from it originate the en- amel organs of the teeth, as well as the bulbs of the hair and the epi- thelium of the glands. Thus early the ]Malpighian layer consists of cells somewhat like those of the connective tissue within, but they stain more deeply and are really epithelial cells, having their origin from the cells of the epiblast. This Malpighian layer is, again, every- where covered by epithelial cells, which are continually formed by it. When the tissue is older, the cells of the stratum ]Malpighii become columnar, or prismatic in shape, standing somewhat vertically over the embryonic tissue beneath. They have large round nuclei, and some authors have stated that they have no cell-wall. Just without these are larger cells, sometimes called youthful cells, and external to these the cells are larger and are more polygonal in form, representing the cells in their middle life, in which the cell- wall has increased in thickness, while the nucleus is found to be smaller. Those cells on the outer surface are the aged cells, consisting almost wholly of formed material. They in time lose their vitality, having undergone changes, until, from the fresh mass of protoplasm, they finally become thin, lifeless scales, which in adult tissue are constantly cast off during the life of the individual. They are reproduced from the cells of the stratum Malpighii. Section of ja\\ , Lii.ijiy ! i-:-, showing the appearance of mucous membrane before the formation of the enamel organ : 1, epi- thelium ; 2, stratum Malpighii ; 3, embry- onic connective tissue. THE DENTAL RIDGE AND DENTAL GROOVE. Fig. 31. 'DO Section of jaw, embryo of pig, showing the epithelium highly magnified : 1, oldest epithelial cells ; 2, the younger cells ; 3, the infant layer, the stratum Malpighii ; 4, the embryonic connec- tive tissue. The epithelium, as has been stated, is derived from the epiblast, and is developed considerably earlier than is the embryonic connective tis- sue beneath. The Dental Ridge and Dental Groove. On that portion of the jaw which is to become the alveolar border, between the fortieth and forty-fifth days, there is seen a growth of cells, which looks as though it had been pushed up in the form of a smooth ridge. If a section is cut across the jaw at this time, and exam- ined, it will be found that this ridge con- sists of a mound of epithelial cells which some writers have called the maxillaey EAMPART. This growth of cells is seen to have had a more energetic growth inward into the substance of the embryonic tissue than it has had outward, so that a groove containing epithelium is formed around the entire upper border of the jaw, and in this condition has been called the tooth band. Fig. 32. M ) Section through the jaws of human embryo, showing developing en- amel organs. (Section by Dr. Sudduth.) 56 EMBRYOLOGY AND HISTOLOGY OF DENTAL TISSUES. Fig. 33. ,1 Section of lower jaw, embryo of pig, showing the lirst stage of growth in enamel organ : 1, epithe- lium ; 2, stratum Malpighii ; 3, dental groove : 4, commencing growth of temporary enamel organ ; 5, Meckel's cartilage ; 6, forming bone of jaw. (Section by Dr. Sudduth.) The cells of the laver next the embryonic connective tissue are always more or less columnar. They are directly derived from, and are a ])art of, the stratum Malpighii. It was the loss of this epithelial tissue, per- FiG. 34. Section of jaw, embryo of pie, showing growth of enamel organ : 1, epithelium : 2, stratum Malyjighii : .3, first stage in growth of enamel organ of temporary tooth ; 4, embryonic connec- tive tissue; 5, developing bone of jaw. THE DENTAL BIDGE AND DENTAL GROOVE. Fig. 35. 57 Section of jaw, embryo of pig, showing growth of enamel organ: 1, epithelium; 2, Malpighian layer ; 3, second stage in growth of enamel organ ; 4, embryonic connective tissue. Section of jaw, embryo of pig, showing growth of enamel organ : 1, epithelium ; 2, second stage in growth of enamel organ ; 3, embryonic connective tissue. 58 EMBRYOLOGY AND HISTOLOGY OF DENTAL TISSUES. Fig. 37. Section of jaw, embryo of pig, showing growth of enamel organ and zone of dentin-forming tissue : 1, epithelium ; 2, enamel organ ; 3, zone of dentin-forming tissue. Fig. 38. Section of jaw, cmbrj-o of pig, showing growth of enamel i-pithf"-- " ' " ' - '' away from the germ : 1, epithelium ; 2, enamel organ ; .3, dentin germ, (llie enamel organ nas been push awav from the deutin by the knife iu cutting the section, leaving a space between the two.) ,11 LTowth of dentin The enamel organ has been pushed THE DENTAL RIDGE AND DENTAL GROOVE. 59 haps by the action of too powerful reagents, which led Goodsir and his followers to describe the appearance of an open groove, — the Goodsir theory had no foundation in fact, because no such open groove ever existed in that situation. The various foldings found in embryonic tissue no doubt are an ex- pression of an economic provision on the part of Nature in caring for Fig. 39. Section of jaw, embryo of sheep, showing growth of enamel organ and dentin germ: 1, large mass of epithelium; 2, enamel organ; 3, dentin germ; 4, growing jaw. the tissue that is to be taken up by the expansion of the parts during its growth, as eventually they are all smoothed out. R5se's models^ show that the original inflection (stratum Malpighii) at an early stage divides into two portions, one of which, the outer, is nearly perpen- dicular, and is intimately connected with the formation of the lip furrow, whilst that immediately under consideration passes almost horizontally backward into the tissue beneath. At about the forty-eighth day, from the lingual side of this groove, at a point where a tooth is to be formed, a portion of the stratum Malpighii is found growing into the embryonic connective tissue, in ^ Models of Developing Teeth and Jaws. By Carl Eose, M. D. 60 EMBRYOLOGY AND HISTOLOGY OF DENTAL TISSUES. shape somewhat like a bud, and this is the first indication that a tooth is to be developed — the commencing growth of the enamel organ. This ingrowth increases, and assumes the shape of a tubular gland, pushing its way into the connective tissue. It may now be called an EPITHELIAL CORD, and at the end farthest from the epithelium proper a growth of cells takes place, this part expanding from the multiplica- tion of cells within, which causes it to assume the form of a Florentine flask. Just at this time, at a point somewhere between this expanding part and the Malpighian layer above, a budding takes place from this cord, which is the commencing growth of the enamel organ of the permanent tooth. A change is taking place in the embryonic tissue just under the flask-shaped enamel organ ; a very active growth of cells is seen to be Fio. 40. Section of jaw, embryo of pig, showing growth of enamel organ and dentin germ: 1, enamel organ ; 2, dentin germ ; 3, growth of jaw ; 4, tongue. going on, and this activity results in the formation of a pajnlla, the first stage in the growth of the dentin germ. As the enamel organ enlarges by an increase of cells within it, the borders of its base grow inward, covering the dentinal papilla like a cap or hood, enclosing it at its base. The cells within the enamel organ are seen to have changed ; they are no longer like epithelial THE DENTAL RIDGE AND DENTAL GROOVE. 61 formations, but form a reticulum and have a stellate appearance when seen in section. While the change in form of the central cells of the enamel organ is taking place, the dentin germ is assuming the form of the future tooth- point. From the base of the dentin germ, connective tissue is being Section of jaw, embryo of pig, showing development of temporary molar tooth : 1, enamel organ 2, dentin germ. formed around the enamel organ, like the outer walls of a bag, this layer being the wall of the dental sacculus ; and when the enamel organ is nearly enclosed, the epithelial cord that connects it with the Malpighian layer breaks up into epithelial clusters ; some of which wander toward the Malpighian layer, while others cluster to the wall of the sacculus, where it is supposed they become absorbed. In their origin the sacculus and dentin germ are identical, springing as they do from the embryonic connective tissue. At this time there is no evidence of a basement membrane. When the enamel organ and dentin germ become enclosed in the sacculus, it and its contents become the dental follicle, at which j^eriod calcifica- tion is about to commence. 62 EMBRYOLOGY AXD HISTOLOGY OF DENTAL TISSUES. Fig. 42. Section of jaw, embryo of pig, showiug development of temporary molar tooth : 1, enamel organ ; 2, dentin germ. The Enamel Organ. The enamel organ is now in its perfected state. On examination it is fonnd to be composed of three distinct celhdar forms. The essen- tial layer is the ameloblastic layer of colnmnar cells which rests upon the dentin germ. These are the cells that are to become the enamel cells or amdohlasts. They have become changed by pressure into very symmetrical hexagons, four or five times as long as they are broad, with a distinctly marked nucleus in the part farthest away from the dentin germ. Only the sides of the cells are said to have membranes : they are without covering at either end. These cells are longer just over the point of the dentin germ and are shorter as they approach its base, being here very much like those of the outer layer, the external epithelium of the enamel organ. This outer layer is composed of cells which are roundish, a little longer than they are wide, and seem to l)e losing their columnar form. Indeed, soon after calcification has commenced these cells disappear.^ ^ It is a question what becomes of tliem. Some autliorities tliink that tliey are the origin of Nasmytli'.'; membrane, but this is very doubtful, for investigation shows tliat THE ENAMEL ORGAN. 63 Just within these two epithelial layers there is found the second im- portant layer of cells, and this layer has been named the stratum inter- medium (see Fig. 54). The cells of this layer are intermediate in shape Fig. 43. Section of jaw, embryo of pig, showing development of dental follicle and first stage in the growth of the permanent enamel organ ; also the formation of walls of the sacculus : 1, epithelium ; 2, Malpighian layer ; 3, enamel organ ; 4, dentin germ ; 5, outer wall of sacculus ; 6, inner wall of sacculus ; 7, hud of enamel organ of permanent tooth ; 8, growing jaw. between the ameloblasts and those of the stellate reticulum. The layer was first described by Hanover, and is thought to be a supplying and nourishing layer to the ameloblasts. Over these they remain, while everywhere else they disappear as calcification progresses. It is prob- able that they give birth to new enamel cells as the circumference of the enamel layer increases by growth. By careful examination it will be found that they are connected by minute processes with the enamel cells and also with the stellate cells of the central portion. Dr. Lionel Beale first made the statement that a vascular network lies Avithin the stratum intermedium. This fact has recently been confirmed by other English they are completely lost some time before the completion of the calcification of the enamel. Just after a layer of dentin has been formed, everywhere upon its surface are seen the enamel cells, ready to form the enamel, and no trace of the outer epithelium can be seen. It has disappeared from that part in the perfected enamel organ. 64 EMBRYOLOGY AND HISTOLOGY OF DENTAL TISSUES. workers, for Tomes mentions the fact that Prof. Howes and j\lr, Ponlton have demonstrated this vascular network in the stratum intermedium of the enamel organ of the rat. Dr. J. Leon Williams, in an article on " The Formation and Struc- ture of Dental Enamel," ' demonstrates with his photo-micrographs the existence of this vascular network in the stratum intermedium of the rat which had been previously seen by these English observers, but it is to be remembered that this vascular network forms after the outer Fig. 44. Section of jaw, embryo of pig, showing development of dentin germ and enamel organ of per- manent tooth : 1, epithelium ; 2, enamel organ ; 3, dentin germ ; 4, budding of enamel organ nf nprmjlTiHtlt tfinth ! 5. dfiVf^loninsT iaw. of permanent tooth ; 5, developing jaw. portions of the enamel organ have disappeared, and only when the con- nective tissue of the jaw is in contact with the cells of the stratum intermedium. The third form of cells fills up the central portion ; they appear star-shaped, and have been called the stellate reticulum of the enamel organ. Between the cells is to be found a fluid rich in albumin ; the consistence of this is somewhat like a jelly ; indeed, enamel organs have been called enamel jelly or enamel pulps. Tomes states that the function and destination of the stellate reticulum is not very clear. Enamel can be very well formed without it, as is seen among reptiles ^ Dental Cotfinof^, February, 1896. THE ENAMEL ORGAN. 65 and fish, and even in mammalia it disappears prior to the completion of the enamel. It has been supposed to have no more important function than to fill up the space subsequently taken up by the growing tooth. Kolliker does not agree with this. He states that the stellate reticulum is certainly of great importance in the building up of enamel, and, owing to its richness in albumin and the gelatinous mass in its meshes, is, figuratively speaking, a pantry from which the enamel membrane (the ameloblasts) derives the material for its growth, — being some distance from blood-vessels. The cells of the stellate reticulum are characterized by the great length of their communicating processes. Dr. Sudduth thinks that Fig. 45. " H -^ Section of jaw, embryo of sliecj), showing development of dentin germ : 1, Inyer (portion of) of ameloblasts ; 2, external epithelium of enamel organ (most of the stellate reticulum has been washed out) ; 3, enamel organ of permanent tooth ; 4, dentin germ ; 5, whorls of epitlielial cells caused by breaking up of neck or cord of enamel organ ; 6, part of stellate reticulum. this appearance is largely due to shrinkage. He says : " I fully believe that if we could examine these cells at once before any shrinkage occurs, we should be able to prove the fact that in life they are not stellate but 5 66 EMBRYOLOGY AND HISTOLOGY OF DENTAL TISSUES. large polygonal cells." Dr. Williams has shown ^ that this supposi- tion of Dr. Sudduth is a fact. In his photo-micrographs he has clearly demonstrated the cell contents filling in the spaces between the stellate tissue. He shows them to be very perfect nucleated cells lying in the so-called stellate reticulum, which is really the slightly modified cell wall. The " stellate reticulum," then, may be regarded as a storehouse of Fig. 46. Section of jaw, oinlii \ - .1 | i_'. slmwiiig developing tooth (section teased away from tooth to show the fold in tlie enamel substance): 1, enamel organ; 2, enamel substance not yet calcified; 3, layer of formed dentin ; 4, a fold in the enamel substance ; 5, dentin pulp ; 6, folds at base of dentin germ; 7, developing bone. the calcium salts from which the first-formed layers of enamel are sup- plied. Tliat calcium salts exist in the meshes of the stellate reticulum may be proven by placing a droj) of dilute nitric acid on the slide when it passes under the cover-glass. The globules or granules Avhich were noticed there disappear as the acid reaches them, and bubl)lcs accumu- late and are forced out from under the glass cover. After the calcify- ing ])rocess commences and enamel is forming, the calcium salts are sup})lied by a rich plexus of blood-vessels now in direct contact with the cells of the stratum intermedium, all other portions of the enamel organ having disapj^eared from this })art. Indeed, it is difficult to demonstrate clearly the cells of the stratum intermedium after any ' Dental Cosmos, February, 1896. THE ENAMEL ORGAN. 67 considerable portion of the enamel has been formed ; they appear to have l^een lost in the connective tissue which is everywhere above them. The origin of the enamel organs of the -permanent teeth may be de- FiG. 47. Section of incisor of rat (X 175) : a, blood-vessels with corfjuscles in situ ; 6, branch of same de- scending to supply capillary loops about secreting papillae; c, ameloblasts. (Dr. J. Leon Williams' specimen.) scribed in general as follows : From the neck of the enamel organs of the twenty deciduous teeth, midway between the stratum Malpighii and the temporary enamel organ, growths in the form of buds are being Section of incisor of rat (X 80): a, capillary loops torn out of secreting papillae; b, secreting papillse after removal of capillary loops ; c, ameloblasts ; d, enamel ; e, dentin. (Dr. J. Leon Williams' specimen.) formed, increasing in length, and these result in the formation of the enamel organs of the permanent teeth, their growth taking place on the lingual surface of the temporary teeth. Soon after this, the tern- 68 EMBRYOLOGY AND HISTOLOGY OF DENTAL TISSUES. Fig. 49. ^f^5#^^i^^%^ f^-^ u\ ■V**. Section of jaw, embryo of rabbit; permanent t ntii -^on developing under tlie temporary molar: 1, enamel of temporary tooth ; 2, dental pulp; 3, developing alveolar wall ; 4, permanent den- tin germ. (Section by Dr. Sudduth.) * Fig. 50. :^- '^jg^' Section of developing tooth of human embryo (X 1000) : a, large nucleated cells of middle layer (reticulum) of enamel organ; h, stratum intermedium ; c, ameloblasts. (Dr. J. Leon Williams' specimen.) THE ENAMEL ORGAN. 69 porary enamel organ becomes separated from its cord. Between the temporary enamel organ and the permanent enamel bud, the cord of the temporary enamel organ is seen to be breaking up and losing its connection with the stratum Malpighii ; while the cord for the per- FiG. 51. Section of developing tooth, embryo of calf (X 1000) : a, b, nuclei of reticulum of enamel organ, showing spongiose character ; c, outer ameloblastic membrane ; d, inner ameloblastic mem- brane ; e,f, enamel globules faintly showing nuclear network. (Dr. J. Leon Williams' speci- men.) manent tooth appears as a continuation of the Malpighian end. The cord for the permanent incisor in the human embryo is formed about the fifth month, and while descending into the embryonic connective tissue, assumes a spiral form of growth, as do the necks of most of the enamel organs of the permanent teeth, growing down to take their positions under the temporary teeth, where they go through all the changes that 70 EMBRYOLOGY AXD HISTOLOGY OF DENTAL TISSUES. have been spoken of in describing the growth of the temporary enamel organ. Dr. Sudduth says that as a rule the cords for the permanent molars arise directly from the epithelium of the mouth, that is, the Malpighian layer. Other authorities state that the first permanent molar only is from the Malpighian layer, as is the enamel organ of the tem- porary tooth. Bodecker is the author of the statement that all the permanent molar teeth are an offspring of the enamel organs of the second temporary molar tooth. The enamel organ of the second per- manent molar is an outgrowth from the first permanent molar ; the enamel organ of the third permanent molar being an outgrowth from that of the second. Von Bruun holds that the primary function of the enamel organ is that of determining the form of the future tooth. He goes so far as to assert that its calcification into enamel in some animals is a secondary function taken on later. In support of this opinion, he says that enamel organs are universal, even where no enamel is found. He holds that wherever dentin is to be found, there is an antecedent " form-building" investment of enamel organ. The Dentinal Papilla. The dentinal papilla, or, preferably, the dentin germ, has its origin in the embryonic connective tissue of the jaw. Sometime about the second month of foetal life, as the enamel organ of the first-forming teeth assumes its flask-like shape, and the cells within its central portion are seen to be differentiating, just under it is noticed an area of dense tissue, in shape somewhat like a crescent. It is distinctly outlined by its dense and active cell-multiplication. This is the first indication of the commencing groAvth of the dentin germ. As the enamel organ enlarges, and assumes the shape of a surrounding cap, a papilla-like growth takes place coincidently with it. About the ninth week it assumes the pointed form of the future incisor. With these changes the outer layer of the connective-tissue cells next the enamel cells will be found to have changed their form, and to have assumed a very distinct columnar appearance, forming a layer somewhat like the enamel cells, but broader. This layer has been falsely called a membrane, " mem- brana eboris " or membrane of the ivory. But it is not a membrane, and all recent authorities ignore it. If the tissue has been carefully prepared, minute glistening bodies are seen, under the higher powers of the microscope, within the substance of the germ. These are calco- spherites, and are seen everywhere near the odontoblastic layer in the dentin germ, as well as in the enamel organ, near the enamel cells. They are mostly minute globules. Some are larger than others, caused undoubtedly by several merging together. They indicate that the THE DENTAL FOLLICLE. 71 process of calcification is about to begin, and are constantly present while it is going on, throughout the process of the formation of the tooth. Dr. Sudduth is authority for the statement that there is no real union between the dentin germ and the enamel organ. There exists no intimate connection between the two surfaces other than that of per- fect adaptation to each other : vessels or nerves have never been dem- onstrated to pass from one to the other. The relation is analogous to that sustained by the epithelium and dermal layers of the mucous membrane of the oral cavity, from which they have their origin. Bodecker, on the other hand, states that there is a connection between the two. He says that when the enamel organ is detached from the papilla — as it frequently is, in sections — its outer surface appears beset with an extremely delicate fringe, the true connection between the pa- pilla and the enamel organ. The Dental Follicle. The walls of the dental sacculus have their origin in the area of tissue which is so plainly marked by its increasing growth, seen just under the enamel organ while in the shape of a flask. At this early stage are seen, from the outer edges of this area of tissue, encircling processes which, as the dentin germ forms, grow rapidly up, surrounding the enamel organ on all sides (see Fig. 52). Some authorities have stated that the dental sacculus does not wholly cover the enamel organ, but in the collection of the writer are specimens where its walls are seen to completely cover the dentin germ, so that it apparently is wholly enclosed. The bone of the jaw is now forming rapidly about it (mak- ing a nest, as it were, in which the sacculus and its contents, now the dental follicle, rest. The cells within the tissue of this sac are found to have separated by growth into two layers. They have not changed their form, but remain connective-tissue cells. The outer layer is seen to be much denser, and very much more vascular than the inner one, and this is to form the dental periosteum ; the inner one is said to form the cementum of the root. This differentiation of a portion of the dental sac into a softer and looser tissue, but little firmer than that of the stellate reticulum of the enamel organ, has been thought by Magitot to be sufficiently pronounced to justify him in calling it a distinct organ, — the " cement organ." But the existence of such an organ is doubted by many authorities. Prof. Sudduth is of the opinion that the tissues of the sacculus do not arise wholly from the base of the dentin germ, but largely from a conden- sation of the fibrous connective tissue in which the enamel orran lies. The follicular wall just over the surface of the enamel organ is often- 72 EMBRYOLOGY AND HISTOLOGY OF DENTAL TISSUES. times found in folds. These have been called " papilliform eminences," and are seen to be projecting into or near the enamel cells. To this appearance some authors attach considerable importance, but it is Fig. 52. Section of jaw, embryo of pig, showing dental follicle: 1, dental follicle, consisting of enamel organ, dentin germ surrounded by the sacculus within the substance of the jaw ; 2, jaw-bone ; 3, tongue ; 4, papillary layer of tongue. doubtful if it has any significance. It, like the folds in many other embryonic tissues, is to be taken up by the expansion of the part by groAvth. In regard to the cement organ, Tomes says : " In those creatures which have cementum upon the roots of the teeth only, no special cov- ered organ exists ; but osteoblasts, which calcify into cementum, are furnished by the tooth sac." The gnbernaculum is a thin fibrous cord of dense tissue, connecting the permanent tooth follicle in its bony shell with the gum tissue just back of the neck of the corresponding temporary teeth. It is a struct- ure of no importance. CALCIFICATION. 73 Calcification. Calcification is a process by which organic tissues become hardened by a deposition of salts of calcium witliin their substance. In the intercel- lular tissue and in the substance of the cells themselves, these salts are deposited by the rich blood supply always near. They are deposited in minute particles and in such fine subdivisions as to make it difficult to demonstrate many of them even with the higher powers of the mi- croscope. The intercellular substance, either a protoplasmic or gelati- nous fluid or semifluid, contains the calcium particles. In it they change their nature chemically, uniting with the albuminous organic substance of the part, and form small globular bodies which have been called calco-spherites ; and these, blending or coalescing at the point of cal- cification, form a substance called calco-globulin. This calco-globulin, which is a lifeless matter, has been deposited through the cells into the gelatinous substance, where, by a further hardening process, it becomes the fully calcified matrix. Mr. Rainey, and later Prof. Harting and Dr. Ord, have devoted much time to the study of this substance. Mr. Rainey found that if a soluble salt of calcium be slowly mixed with another solution capable of precipitating it, the resultant calcium salt will go down as an amor- phous powder, and sometimes as minute crystals. But when the cal- cium salts are precipitated in gelatin, the character of the calcium salts is materially altered. Instead of a powder, there were found various curious, but definite, forms quite unlike the crystals or powder produced without the intervention of the organic substance. Mr. Rainey found that if calcium carbonate be slowly formed in a thick solution of albu- min, the resultant salt has changed in character ; it is now in the form of globules, laminated, like tiny onions, which coalesce into a laminated mass. In this Mr. Rainey claims to find the clue for the explanation of the development of shells, teeth, and bone. At a more recent date. Prof. Harting took up this line of investiga- tion and found that other calcium salts would behave in a similar man- ner. The most important addition to our knowledge made by Prof. Harting lay in the very peculiar constitution of the " calco-spherite," by which name he designated the minute globular forms seen and described by Rainey. Mr. Rainey found that albumin actually en- tered into the composition of the globule, since it retained its form even after the action of acids. Prof. Harting has shown that the albumin left behind after treatment of a calco-spherite with acid is no longer ordinary albumin ; it is profoundly modified, becoming exceedingly resistant to the action of acids. For this modified albu- min, he proposes the name " calco-globulin." Microscopic glistening 74 EMBRYOLOGY AND HISTOLOGY OF DENTAL TISSUES. globules like those described above are constantly seen at the edges of tissue where enamel, cementum, dentin, or bone are to be formed or are forming. Robin and Magitot have described isolated spherules of calcium salts as occurring abundantly in the young pulps of human teeth, as well as those of other animals, and Tomes suggests that per- haps all deposits of calcium salts commence in this way. These micro- scopic globular bodies are calco-spherites. CALCIFICATION OF THE DENTIN. Although the enamel organ is first formed, with its layer of amelo- blasts all ready to commence the process of calcification, it is at the tip and within the substance of the dentin germ where this process really begins. The papilla has assumed the form of the point of the future tooth crown, the cells everywhere upon its outer surface — the Fig. 53. Section of growing tooth of calf at birth, showing the layer of odontoblasts and fibril cells attached to tlie forming dentin. odontoblastic layer — are found to be actively at work, forming the first cap of dentin. They are seen to be imbedded in a transparent and structureless gelatinous substance, in which small globular masses are already forming. The cells are clearly defined, being somewhat broader than the ameloblasts just above them, and like them are seen to be in a single layer, which has been named the " membrana eboris," but it is not a true membrane (see Figs. 54 and 55). The cells are found to vary in form, according as the formation of the dentin is actively going on or not. During the period of their greatest activity they are broad at the end directed toward the dentin cap, so as to look almost abruptly truncated, having as many as three or four, in some instances as many as six, dentinal processes proceeding from a single cell. Boll having counted as many as six. The cells are finely granular, and are, accord- ing to AYaldeyer and Boll, destitute of membranes. The nucleus is CALCIFICATION. 75 oval and lies in that part of the cell farthest from the dentin, and is sometimes prolonged toward the dentinal processes so as to be ovoid or almost pointed. The dentinal process passes into the canals of the Fi<4. 54. 4 Fig. 55. Section of developing tooth, embryo of pig: 1, stellate reticulum of enamel organ ; 2, stratum intermedium; 3, internal epithe- lium of enamel organ (ameloblasts) ; 4, forming odontoblasts ; 5, pulp tissue. Section of jaw, embryo of pig; 1, ameloblasts showing Tomes' processes : 2, layer of formed dentin ; 3, odontoblasts ; 4, pulp tissue. (Sec- tion by Dr. Sudduth.) dentin, and it frequently happens that the layer of odontoblasts is slightly separated from the dentin in making a section, when these processes, which constitute the dentinal fibrils, may be seen stretching across the interval in great numbers. Intermediate between the per- manently soft central fibrils and the general calcified matrix is that portion which immediately surrounds the fibril, namely, the dentinal sheath. In 1891 Mr. Mummery noted, as the dentin was forming, the appearance of connective-tissue fibers, or bundles of fibers, just in ad- vance of the main line of calcification. Their high refractive index suggested their partial calcification, the processes being continuous from the formed dentin to the general connective tissue of the dentin germ. He found in a young developing tooth a distinct reticulum of fine fibers passing between and enveloping the odontoblasts. By careful focussing, he saw these fibers gathered into bundles and incorporated with the matrix substance of the dentin, out of which they seemed to spring. The origin of these fibers seems to be from connective-tissue cells, which are found everywhere in the formative pulp next the odontoblastic layer, and also, as he has demonstrated, between the odontoblasts themselves. These fibers are the scaifolding on which the tooth matrix is built up ; they are incorporated in the matrix of the dentin, and form really the basis of its substance. 76 EMBRYOLOGY AND HISTOLOGY OF DENTAL TISSUES. The odontoblasts are modified connective-tissue cells that superin- tend the deposition of the calcific material which is to form the calcified matrix. The thickening of the dentin is by successive deposits of this material in the form of layers which calcify. Fibrils from the odonto- blasts remain wdthin the formed and forming dentin as the persistent organic contents of the canals. This forming of the dentin is at the expense of the dentin germ, which is thus gradually reduced until it becomes, when the tooth is fully formed, its pulp. Thus it is seen that dentin is a secretion in the form of calcific material coming from the abundant blood supply in the pulp tissue near the odontoblasts. The material is given out from the cells in a globular form (calco-spherites) into a protoplasmic fluid, or semifluid, found everywhere against the calcifying dentin. In this substance is the scaffolding of fine con- nective-tissue fibers spoken of by Mr. Mummery, of London. The calco-s})herites, meeting against the formed dentin, coalesce into a layer of calco-globulin ; and this, becoming fully calcified, forms an additional layer of dentin, and the process continues until the tooth is formed. By the deposition of calcium salts into the protoplasmic layer calco- globulin is formed, and by its calcification the dentin tissue becomes a homogeneous mass, penetrated by many i)arallel canals filled with the persistent dentinal fil)rils. Beside these parallel canals with their fibrillar contents manv lateral canals are seen branchiuir ofl" from the main caiials and anastomosing with neighboring canals. Exceptions may be taken to many of the statements of histologists in this field ; many or most of which are traceable to faulty methods of technique. Processes which involve the securing of specimens while they are yet warm are greatly preferable. These are placed in a quarter of one per cent, to one-half of one per cent, solution of chromic acid, which is changed several times a day, for three or four days. At the end of this time the edges of the dentin which were calcified are found to be sufficiently softened to make a number of sections. The teeth are then taken from the acid solution, washed in distilled water, and placed in a solution of gum arable for several hours, next transferred to a solution of alcohol to abstract the water. Paraffin and lard are melted together and poured into a convenient mould. When this clouds in the process of cooling, the tooth, which has had its outer surface dried as much as possible with bibulous paper, is placed in it and the whole allowed to cool. The microtome for this purpose should permit the immersion of both tissue and knife when the sections are cut. These sections float off in the fluid, and remain there until used. Sections are cut until the calcified tissue is reached. The sections are placed in distilled water for a few minutes to dissolve out the CALCIFICATION. 77 gum, and then mounted in glycerin jelly. The difference in the appearance in the tissue prepared by this method is marked. It is seldom necessary to stain tissues which are to be studied under the higher powers of the microscope. The dentin matrix is mainly a connective-tissue calcification, and it should be remembered in examining sections of forming dentin that Fig. 56. Section of growing tooth of calf at birth, showing the formed dentin, the layer of calco-globulin and two odontoblasts ; a fibril is seen at the side of one of them. sections are seen at that stage of growth at which the death of the part left it. In some the odontoblasts are seen square and abrupt against the calcified matrix, having no appearance of other tissue between them. Fig. 57. A *LfiJj._ '*ft'^ rxite^- Section of growing tduth of calf at birth, showing the layer of oiLmtoMasts ^^iuare and abrupt against the forming dentin; some of the fibril cells, or dentin corpuscles, that are pear- shaped, are seen running between them. In others the odontoblasts are seen square and abrupt against a laver of a fibrous, gelatinous tissue, w4iich is seen to be filling with globular 78 EMBRYOLOGY AND HISTOLOGY OF DENTAL TISSUES. masses (Fig. 56). This layer is between the odontoblasts and the cal- cified matrix. A section from another embryo will show a different picture. Here is seen a layer of mostly pear-shaped cells, not quite afyainst the calcified matrix, showing their fibrils drawn out and run- ning into the canals of the matrix (Fig. 57). There is no appearance of a gelatinous layer, Avhile here and there against the calcified matrix are what appear to be used-up odontoblasts, only portions of them showino". The cells in this picture rarely show more than one fibril running into the canals of the matrix. Again, a section from another tooth will show layers of calco-globulin merging together and forming a new layer of the matrix, and, in this, parts of the odontoblasts seem to lose their identity (Figs. 58-60). An important fact not to be lost sight Fig. 58, Section of develoiiing tooth of calf at birth : cross section showing first-forming layer of dentin matrix. The calco-spherites are seen forming a layer of calco-globulin which by further calci- fication is to become the matrix. of is that all of these appearances indicate the different stages in the growth of the dentin matrix. Conclusions cannot be drawn from any one of them, so all must be studied. These appearances are not found at the early stages alone ; they are also seen when the matrix is nearly formed. The odontol)lasts are masses of protoplasm without membranes, and are at a certain stage of growth square and abrupt against the matrix (Fig. 57). It is an easy matter to find among them, and immediately adjacent, large numbers of pear-shaped cells, tapering into the dentinal fibril. The odontoblasts, when calcification is active, are scarcely more than masses of protoplasm, filled with minute globules (Fig. 61). The fibrils which a]>pear to come from them, described ])y Tomes as pulp, lateral, and dentin processes, originate probably from a fibril- CALCIFICATION. Fig. 59. n rt'AV < 79 Section of growing tooth of calf at birth, showing hbrils, libril cells and odontoblasts ; also the layer of calco-globulin and the forming dentin. Fig. .60. ' -^2^'^ t ■./-': ;': ' : ; ■ "^ . f 4 Section of growing tooth of calf at birth, showing fibrils, fibril cells, and odontoblasts. The pulp has been teased away, leaving these cells clinging to the formed dentin. Fig. 61. Section of growing tooth of calf at birth, showing odontoblasts and fibril cells. 80 EMBRYOLOGY AND HISTOLOGY OF DENTAL TISSUES. forming cell. These pass through the soft substance of the odonto- blasts (protoplasm) and seem to be a part of them, but in fresh, young sections the so-called processes move in the substance of the odonto- blasts by pressure on the cover-glass, and the fibril may be traced to a jjear-shaped cell beyond (Fig. 01 ). There will usually be found as many processes going out from sides or ends of the odontoblasts toward the pul]) as there are going into the matrix from the dentin end of the cell. In cross sections of the odontoblasts, delicate light spots are seen in the substance, which are probably the cut fibers. When the layer of odontoblasts is teased away from the forming dentin, fibrils are seen bridging the gap, apparently offshoots from the odontoblasts ; but on careful examination there will usually be found a decided line of demar- cation across the fiber at the point where it meets the square end of the Fig. 62. Section of growing tooth of calf at birth; odontoblasts that were square and abrupt against the forming dentin, showing the line of demarcation between the cell and the fibril. They are attached to the pulp. odontoblast (Fig. 62). This line seems to show that the fibril was not continuous with the protoplasm of the cell. Other sections which have bi'cn separated by teasing, show odontoblasts having their side masses of protoplasm drawn away from the fibril which api)arently has run through it. Some of this protoplasm is left upon the fibril, giving it a ragged ap]>earance as it ]xisses from a canal in the matrix across to the separated pulp tissue, bridging the gaj). The pear-shaped cell has perhaps a more important function than the odontoblast proper. It is to su])ply the life and nourishment to the whole of the calcified matrix, as the bone corpuscle within its lacuna supplies life and nourishment to bone and cementnm. Minute calcium globules or calco-spherites are seen to be arranging themselves against the already formed matrix, where they collect in large CALCIFICATION. 81' Fig. 63. ft: % Section of human tooth, showing globules of calco-globulin which have been deposited in the gelatinous layer by the odontoblasts ; these have been pulled away in making the section. (Section by Mr. Mummery.) Fig. 64. ^>W:iM jV^v Fig. 65. Fig. Sections of growing tooth of calf at birth, showing formation of layer of masses of calco-globulin to form layer of dentin. 6 82 EMBRYOLOGY AND HISTOLOGY OF DENTAL TISSUES. numbers, and lose their individuality by merging into one another, form- ing larger globules, of various shapes and sizes (Fig. 63), seeming to take into their substance portions of the odontoblast. These globules enlarge until they reach their typal width, expand laterally, meeting and coalescing with others. The minute globules are seen within the odontoblasts of diiferent sizes, all having a glistening appearance, some- thing like fat globules in cells. The early layers formed by the glob- ules are about the width of the band of formative cells. (See Figs. 64, 65, 66.) CALCIFICATION OF THE ENAMEL. The statement made by Tomes and others that enamel is formed by the actual conversion of the enamel cells into the enamel rods is an erroneous one. The enamel cell does not calcify ; it superintends the laying down of calcific material which is to form the rod. For the earliest deposit of enamel the calcium salts are stored in the meshes of the so-called stellate reticulum, and as the first enamel forms, the enamel organ proper disappears at this point. Only the two inner- most layers remain ; these are the layer of the columnar cells (amelo- blasts) over the forming enamel, and a layer of cells somewhat resem- bling connective-tissue cells (the stratum intermedium) over these. The two layers are separated by what appears to be a line of tissue which has been called a membrane. The embryonic connective tissue of the jaw is now in direct communication with the stratum intermedium, and a rich blood supply is developing near the point of juncture. The function of the cells of the stratum intermedium is supposed to be the supplying of new cells to the amelo- blastic layer as they may be needed by the increase in the circumference of the enamel, as new enamel is formed ; to furnish the organic fluid in which the calcium salts are deposited ; and to su})])ly the fine network of fibers, the scafiblding upon which the enamel rods are to be l>uilt. Prof Sudduth is the authority for the statement that enamel is nothing more or less than a coat of mail supplied l)y Nature to protect the dentin. The enamel cells that have l)een ])roper]y prci)ared and not shrunken will be seen filled with minute globules. The authorities who speak of Fig. 67. lI.-^-- m\^~7T: 'i>\ Section of liuman ui\ ilii|iiii>; i 0- cc » *e ci aj a 03 w > fc, O " ~ ^ csx; 223 o = g u :S cj a^ -, M «/a a _^ = o "3 w y "— 'i bi ^5 =2 w -a §3 a^ c/ ^ •Sas C o cj O fcC "3^ O ffl in a - .=2 OS'S 2 oaii Tt I* s5 =s s -; ^ G r; 53g.2 t^ 1 ^ taOQj ■5 -" S« o •s'la o'CS "* as g 03 0) Sas Cbco < , !='d a p S-S ^ o ii as p. cS •^1 Ik's •" a o 3 . =*< if . . cSS a-s a uo'o oo.a _a--+^-j "o a M s a " a§ =iS 3 a'" •^co §0 .§0 CiO od>a ^. s a ^ ,£3 »c ^ < . a II 13 « ft a ft |3 > s ■ o a a o gi| 003 -^ --3 3 3 «— cS ■o !^'3 s a — 5^ ^ o <2„ 2 Sla C c ce <«£ ..a tw o l-S^ 3 2 = 2 o go *^ *^ 1*H ^ n3 3 o 111 2 i 5 gI3ft oS'-3 £)->^+^ j3 s ^ ^ c 2|| Si 00 '=^ ^ "" 2 co^g ill rt< t- 00 a T1 M I> ^ SoS 23 03: So2 (5 CO S05o 1=1 1.0 ■^^ S2-^S lO"*^ CO CO "^ to*^^ CI CO 00 CO ■^ S c^ e^ CO CO Tjt lis r^ - o o •nl ■^ CO C5 t^ lO T}< CO (M — i> X =c: OJ O^ oqo«= ot-: c« •> C". ". i--^ I- ©■* t-^ CO CO* CI ci-iS oi-^co S^S i-o-i->tg S^2 fi*^S 90 EMBRYOLOGY AXD HISTOLOGY OF DEXTAL TISSUES. In a recent paper on the Histology of the Pulp, Ijy Erwin Hoehl, he states that the cells of the pulp show in the different life periods cha- racteristic differences in form and number. Three kinds are found, which arise from one another by metamorphosis in the following way : (1) Round cells with large nucleus and scanty protoplasm. (2) Irregu- larly shaped cells with many freely anastomosing processes. (3) Spindle- shaped cells with the same character as the foregoing. The changes of the cell form begin at the periphery and proceed toward the centre of the pulp. The outermost peripheral layer of the branched cells contains the elementary ot primary odontoblasts. Centralward from these is a cell layer which, with reference to the function of its elements, is called the conjugation cell layer. The secondary odontoblasts arise by conjugation of the primary odontoblasts with the conjugation cells, and they form the dentin. The conjugation processes probably cease only with the completion of growth in the tooth. Of the peripheral processes of the primary odontoblasts the larger one represents what will be the future dentin fibril. The increase of cells seems to be dependent upon the development of the capillaries, inasmuch as more cells are found where the distribution of capillaries is most dense, /. e. on the periphery of the pulp. The gradual decrease of the number of branch cells in the centre of the pulp during the course of development is because only trunk vessels are found here. In the place of these destroyed cells we find a delicate cellular network which is probably derived from the numerous anastomoses of the cell processes. Xext to or just within the odontoblastic layer is seen a bright zone variable in Avidth ; this is the so-called WeiVs layer. Between this and the fi])rous or central portion of tlie pulp is an intermediate layer which forms a contrast with the delicate fibrous elements of Weil's layer, and in this way AVeil's layer is made visible. The ground substance of the pulp by a certain method of treatment shows a dense interlacing of fibrillse which are arranged parallel to one another and seem to run in the direction of the axis of the tooth. The Gum. Gum tissue is the same as that of the general mucous membrane of the moutli. It is more dense because it is bound down to the l)one by numerous fibers of its own, and it is also united with the periosteal tissue which s])reads into it in every direction. Numerous large single and compound papillae are seen. The blood supply is abundant, but nerve tissue is not often found. The histological ap])earances which look like young enamel organs are the glands of Serres. Xear develop- ing teeth epithelial clusters are' frequently seen, the remains of the dis- appearing necks of the enamel organs. The cells of the stratum Mai- THE PERICEMENTUM OR ALVEOLO-DENTAL MEMBRANE. 91 pighii of the epithelium are seen to be in columns, and from these new cells are formed, which flatten and lose their vitality as they near the outer surface, where they are given otf as lifeless scales. The Pericementum or Alveolo-dental Membrane. This is a formation of fibrous connective tissue, having its origin from the outer layer of the sacculus (Fig. 74). It differs from the gum tissue in that it is not so dense. Tomes speak of it as having a rich supply of nerve fibers. Fig. 74. /' / ^.::^^. .^- . ^J. ,__ , .^, f^ Alveolar dental membrane (.section from jaw of kitleni ; 1, alveolar dental membrane : 2, bone of alveolus : 3, dentin. The pericementum passes into the gum at the tooth neck, where it is thicker than at any other part. It is seen to be everywhere connected with the periosteal membrane of the alveolar process. The general direction of its fibers is across, slightly wavy, downward from the alveoli to the tooth root. In the young tooth there are no breaks in the continuity. There is no appearance of two separate membranes, one for the root and the other for the alveolus ; but simply a mem- brane common to both surfaces. 92 EMBRYOLOGY AND HISTOLOGY OF DENTAL TISSUES. The pericementum forms an elastic membrane and acts as a cushion to lessen the concussion when the teeth come together during mastica- tion. Its connective-tissue fibers are seen to pass into the cementum, and within that substance are supposed to be Sharpey's fibers. AVhere the cementum is thicker, it is rich in cellular structure, the pericemen- tum then connects with the cementum by its fibers ; these in turn con- nect with the branches of the cement corpuscles, through these with the granular layer of Tomes, and thence on to the fibrils of the dentin. Nasmyth's Membrane. Concerning this structure Tomes states that — " Under the name of Nasmyth's membrane, enamel cuticle, or per- sistent dental capsule, a structure is described about which much differ- ence of opinion has been, and indeed still is, expressed. Over the enamel of the crown of human or other mammalian teeth, the crown of which is not coated by a thick layer of cementum, there is an exceed- ingly thin membrane, the existence of which can only be demonstrated by the use of acids, which causes it to become detached from the surface of the enamel. When thus isolated it is found to form a continuous transparent sheet, upon which, by staining with nitrate of silver, a reticulated pattern may be brought out, as though it were made up of epithelial cells. The inner surface of Nasmyth's membrane is, however, pitted for the reception of the ends of the enamel prisms, which may have something to do with this reticulate a])pearance. It is exceedingly thin, Kolliker attributing to it a thickness of only one twenty-thousandth of an inch. But, nevertheless, it is very indestructible, resisting the action of strong nitric or hydrochloric acid, and only swelling slightly when boiled in caustic potash. Notwithstanding, however, that it resists the action of chemicals, it is not so hard as the enamel, and becomes worn off tolerably speedily, so that, to see it well, a young and unworn tooth should be selected." The writer's investigations lead to the inference that the membrane is nothing more than the layer of cells of the internal epithelium of the enamel organ, the amelol)lasts, whicli, having performed their function, have filled with calco-globulin and have partially calcified, becoming somewhat like that tissue which we find on the borderland of calci- fication. It is probable that the lacunae found occupying a fissure between the cusps of the teeth, in the enamel, are nothing more than a little of the connective tissue which has become infolded and ossified before the eruption of the tooth. CHAPTER III. THE EXAMINATION OF TEETH PRELIMINARY TO OPERA- TION—METHODS, INSTRUMENTS, APPLIANCES— RECORD- ING RESULTS, ETC. By Louis Jack, D. D. S. The Operator. The attitude of the body of the dental operator has considerable influence upon the ease with which the various positions required in operating may be assumed, and also has some bearing upon the free- dom of his hands. The erect position should be maintained as far as possible and the preponderance of the weight should be sustained upon the balls of the feet. This secures equilibrium and enables movements to be made with little embarrassment. The shoulders should be held well back in order that the arms shall not be cramped, and to permit the respira- tion to be carried on deeply and with quietness. For obvious reasons the breathing should be always through the nose. The precise use of the fingers requires that in each application of the instrument a rest as a fulcrum or base of action should be used, and when force is to be applied a guard in addition is required to give secu- rity to the movement of the hand. The positions required in operating are various, depending upon the situation of the territory of operation and somewhat upon the natural tact of the individual, so that a defini- tion of them is scarcely required. Upon a careful application of the rests and guards depends the graceful and comfortable use of the instru- ments, and by means of them the hand passes by quick and easy grada- tion from the most delicate touch to the safe exhibition of considerable force. Each student should study and practice the use of the various rests and guards until they become by repetition involuntary and appro- priate to the situation.^ The contact with the patient .should be at as few points as possible and should be generally made with the fingers. Examination of the teeth and mouth in all their particulars is a necessary preliminary to the treatment of any diseased condi- ^ To aid in the study see American System of Dentistry, vol. ii. p. 44 et seq. 93 94 EXAMINATION OF TEETH. tion which may appear. The importance of this procedure cannot be overestimated, as on it depends the formation of a correct diagnosis of departures from the normal state and it becomes a basis for the formulation of plans for the treatment recpiired to restore the teeth and the related structures to a state of health, as Avell as to define the order in which the several operations shall be taken up, since an orderly pre- cedence in the treatment of individual teeth is frequently necessary. It is essential that the examination be most thorough, to prevent any failure to detect the least defect ; since an unobserved slight lesion may become a deeper injury in a few months, the consequences of an over- sight may have serious results. Appliances used in Examination. The appliances required to effect thorough observation of every portion of each tooth to ascertain the extent of any lesion are of several kinds, viz. mirrors, magnifying glasses, explorers, floss silk, and wedges. The MIRRORS should be both plane and concave. The plane mirror is important as a means to assist by the reflected image in determining the position of defects ; the concave as an adjunct to effect illumination, as it concentrates the rays of light and also may be used to produce an enlarged image. The enlarged image, however, is less sharp in defini- tion than the image of the plane mirror. Working to tJie Image. — The plane mirror is an important adjunct in all operative procedures connected with the teeth. ]\Iany situations in the mouth do not permit the direct reflection of the rays of light to the eye without assuming positions of the body and of the head of the operator which are awkward and embarrassing to free movement of the hand, as well as necessitating inconvenient and tiresome positions of the head of the patient. These difficulties may be overcome by the move- ments of the hand being directed by the image of the field of the pro- cedure on the mirror. This method of working to the image is at first difficult to the novice, since the images are reversed ; but by continued effort it becomes as easy to make correct application of movements by this method as by the direct rays of light. Further continued practice in this way renders the movements so completely under reflex control that the operator passes from a direct movement to a reverse one, and the contrary, without an apparent effort of the brain. This is equally true in all the various movements, even of those where considerable force is required to be employed. The Qiudity of t/ic Mirror. — These appliances should be always in good condition to enable a clear definition to be received. The best kind of glasses are tliose in wliich the surface is covered by a deposit of APPLIANCES USED IN EXAMINATION. 95 Fig. 75. pure silver. This furnishes a better reflecting surface and is more dur- able than is the so-called " silvering " with tin and mercury. Magnifying lenses of about four diameters are useful ^ _„ /> 1 T • -TIG. lb. to detect minute defects either of the teeth or of the condition 6 .^ of previous operations upon the teeth. They are used either di- rectly to magnify the parts or as a means to magnify the image on the face of the plane mirror when direct rays of light cannot be caught. This latter method gives a clearer definition than the mag- nified image of the concave mirror. The magnifying glass may be the ordinary watchmaker's glass held before the eye by the muscles of the brow and cheek or the lens mounted as shown in Fig. 75. Such glasses are indispensable to the careful practitioner, since with their aid defects of the teeth and of operations may be detected which would escape observation by other means. Explorers are, essentially, prolongations of the fingers ; they convey impressions by their vibra- tions to the tactile nerves, and are principally intended to be applied to parts where direct rays of light cannot reach. They should be of delicate make. The forms re- quired are simple and few. The form shown in Fig. 76, when made of flexible steel, may be bent in such forms as will reach every part of the mouth or may be applied to all surfaces of the teeth. They are best when made of piano wire. No. 18 American gauge, filed to a point and bent to the shape indicated by the figure. At the part a the size of the finer ones should be No. 26, and near the ultimate point, 6, No. 32. The temper of this kind of steel gives sufficient stiffness Magnifying lens. Explorer. 96 EXAMINATION OF TEETH. Fig. 77. ^^^^(] jjlgf) permits the .flight bending to make modifications of the form to meet all re- quirements. The ulti- mate point may be sharpened and renewed at pleasure. The han- dles in which these in- struments are inserted may be of wood, with metal sockets which should be of sufficient leny-th to come into contact with the finger ; or they may be fixed in metal holders, in Avhich case the latter should be tapered to avoid weight and to give balance. Either form of handle should be round, to permit fractional rotary change of direction. Floss silk is used to pass between the ap- proximal surfaces of the teeth at the points which are in too close contact to permit the ingress of fine explorers. In these positions floss silk may detect the presence of superficial softening of the enamel by the character of the friction or by the fraying of its fibers. It also is of use in determining the condition of fillings on approx- imal faces or the presence of a deposit of sali- vary calculus on similar parts. The silk should be slightly waxed in order to bind the fibers. Entire reliance cannot be placed upon the use of silk, since it may in some cases pass slight cari- ous spots without the fibers being displaced, but it frequently furnishes W indications for further ])rocedures by which to establish certainty as to the state of approximal surfaces. Wedc4ES arc used when neither explorers nor silk give jiositive indications of carious action but have raised doubts of the integrity of any part. They may be of wood where the Electric mouth lamp. THi: EXAMINATION. 97 teeth are not firmly fixed, when the space may be immediately made ; otherwise, where the fixation is firm, india-rubber or linen tape mav be forced in. Transillumination of the teeth and of the adjacent parts by the elec- tric mouth lamp (Fig. 77) is sometimes useful in cases of doubt, and is of service also in diagnosis of derangements of the antrum and to test the vitality of the pulp. The Examination. The parts of the teeth most liable to carious action are those which most easily retain deposits of sedimentary matter, food debris, etc. These are the labial and buccal surfaces, where the mechanical relations of the lips and cheeks tend to retain sediment ; the sulci, which by the direct force of mastication have food driven into them ; and the approximal surfaces. The latter are the most important to consider. The interproximal space is a serious predisposing cause of caries, be- cause the counteraction of the tongue and cheek in adapting the food between the occlusal surfaces of the teeth drives the finer particles of the food into the interproximal spaces, where it is retained by capillary attraction and by the apposition of the cheeks with the buccal surfaces of the teeth. This space is usually triangular, the gum forming the base of the triangle. The point where caries usually begins is at the apex of this triangle, where there is the least movement and inter- change of the contents of the space, as here the capillary force is the greatest, so that the fermentative processes of food decomposition are least interfered with. The technique of examination is as follows : After a cursory in- spection of the denture with the mirror, the explorer is applied to the previously indicated surfaces, particular care being used in determining the condition of approximal surfaces, by introdacing the instrument into the triangular space, the point being directed toward the acute angle. It should be drawn back and forth with a slight rotary move- ment so as to impinge the point successively upon the whole approxi- mal surface of each tooth. This movement should be made from the inner as well as from the outer aspect. In this manner the instrument will be brought into contact with every accessible portion of the inter- proximal surfaces. Then the sulci are explored and the buccal smfaces examined. The inspection is thus conducted from tooth to tooth. Next the lines of apparent contact are critically tested with the mirror for evidence of slow changes of structure as shown by discoloration or rapid alterations shown by a milk-like appearance of the tooth surface. Finally, all approximal surfaces which could not be explored are 7 98 EXAMINATION OF TEETH. silked. To do this the floss is wrapped upon the index finger of the left hand, and with the right is drawn between the contact surfaces with a sliding lateral movement. Care should be exercised that no injury be done to the gingival margin of the interproximal space by suddenly and forcibly driving the floss into contact with it. This acci- dent may be effectually avoided by a proper guarding and supporting of the fingers by contact with the adjoining teeth. Practice gives facility in determining by means of the silk the state of the parts in contact. In the inspection of previous stoppings, all margins, particularly those beneath the gum, should be critically inspected. (The tests for pulp exposures are considered in Chapters V. and VI.) The order of examination is best conducted by beginning at the median line of each quarter of the denture, progressing posteriorly with one line of observation and returning to the place of beginning with another line of observation. The Chart Record. — The chart record should at the same time be carried on by the principal, or better an assistant, with the view of Fig. 78. S-EX signifies : In the interproximal space. " Attention— re-examine. " Superfieial softening. " A carious cavity. " At the cervix. " To separate. " To polish. C signifies : Salivary calculus. EX " To examine. ~) " A pulp nearly exposed. 3 " A pulp probably exposed. 3 " A pulp fully exposed. D " A devitalized pulp. securing a complete record of each derangement, for guidance and for reference. The details of the record are indicated in a simjile manner by symbols which are illustrated by Fig. 78, and explained by the glos- THE CHART RECORD. 99 sary. These symbols may be combined, where required, to give fuller expression. From this temporary record important operations when executed may be transferred to a permanent record. The constitutional condition and the texture and density of the dental tissues ; the inherited tendency to diseases of the teeth ; the chemical reaction of the mucous and salivary secretions ; the state of the general health ; the condition of the mucous membrane of the mouth and throat ; the indications presented by the tongue ; the dietary habits and other hygienic relations ; the tendency to catarrhal aifections ; the presence of the rheumatic or gouty diathesis — are all questions which enter into the prognosis and frequently largely determine not only the hygienic directions to be given to the patient, but are of importance, in connection with the age and habits, in deciding whether the restorative operations shall be of a permanent character or only of a temporary nature to preserve the teeth until restored normal functions may make it judicious to perform more enduring operations. The foregoing considerations with respect to the examination of the mouth and teeth sufficiently meet the requirements for beginning rational treatment of dental disorders. CHAPTER ly. PRELIMINARY PREPARATION OF THE TEETH— REMOVAL OF DEPOSITS AND CLEANING OF THE TEETH— WEDGING— OTHER METHODS OF SECURING SEPARATIONS— EXPOS- URE OF CERVICAL MARGINS BY SLOW PRESSURE, ETC. By Louis Jack, D. D. S. Cleansing the Teeth. Before restorative operations are commenced upon the teeth all deposits of salivary calculus ii})on them should be removed and they should be cleansed of the covering of partially inspissated mucus which even in persons of more than ordinary carefulness is liable to be found upon them. This film favors the admixture with it of sedi- mentary matter from food substances and frequently has so much con- sistence as to oifer considerable resistance to its removal, and it pre- vents to a degree the contact of the naked brush with the teeth. Its presence for this reason is detrimental to the preservation of the teeth, since it favors the retention of bacterial forms and starchy matter, the acid produced by the fermentation of which is the exciting cause of enamel solution. This deposit is most frequently formed on the inner and outer surfaces of the posterior teeth, where it invades the inter- spaces and in some cases covers all surfaces which are not directly sub- ject to the friction of mastication. This deposit should he thoroughly removed and all surfaces be then carefully polished. The best means to effect this is to polish the parts with a mixture oi pulverized pumice with glycerin. The glycerin binds the particles of pumice and permits its retention upon the polishing instruments. The persistence of this deposit is shown by the fact that when the pumice is applied it is a moment before tlie ])olishing implement comes into actual contact with the enamel. To be suitable for tliis purpose the pulverized pumice should have been elutriated or passed through a fine bolting cloth to remove the coarse and irregular j)articles which if per- mitted to remain might cause injury to the enamel surface. After the removal a vitreous surface should be given by quick friction with stan- nic oxid ("putty powder"), which also is better applied when combined with glycerin or rul)l)ed up witli vaseline. 100 CLEANSING THE TEETH. 101 Salivary calculus is found precipitated at parts not subject to free friction, such as the buccal surfaces of the molars, the inner faces of the lower incisors, and it frequently invades the interspaces. These deposits also should be displaced and the surfaces polished. The better appliances for the removal of calculus are sickel-shaped scalers of various sizes and forms, which are in- serted beneath the free margin of the gum, when the direction of the move- ment should be obliquely toward the occlusal aspect to avoid injury to the gingival attachment with the tooth. The consideration of the removal of deeply seated salivary calculus where some serious injury has been caused by its presence is treated of in Chap. XVII. Polishing- the Triangular Portion of the Interproximal Spaces. — When this is required an efficient means is to employ gilling twine of sizes proportioned to the space. This is applied by looping one or more strands with a piece of floss silk, when the silk is drawn up- ward into the triangle and then is used to draw the twine into the space, which being armed with suitable powders is drawn to and fro until the absence of friction indicates that the surfaces have become smooth. Abbott's scalers. CARE BY THE PATIENT. Coincident with the preparation above described the patient should be given such instruction as will tend to maintain the state of cleanli- ness. The importance of this should be impressed as a necessary hygienic measure to preserve the teeth. This is to be accomplished by the use of suitable brushes and properly compounded powders. The detergent result of powder is principally effected by the particles be- coming mixed with the film of mucus. This action breaks up the con- tinuity of the film when it and the accompanying sediments are displaced by the friction of the brush. The correct use of the brush requires that it be placed with some degree of firmness upon the outer and inner faces of the teeth and then slightly rotated. The pressure drives the bristles into the valleys, and the rotary movement being away from the gum avoids injury to that structure. The application of this procedure in combination with the use of picTcs and floss silk should maintain a correct hygienic condition of the teeth, upon which, in the light of the present knowledge of the 102 PRELIMINARY PREPARATION OF THE TEETH. causes of solution of the enamel, depends the preservation of the teeth from that source of injury. It has been shown that when sound en- amel becomes attacked, the potent cause is the fermentation of the starchy deposits which are permitted to remain in contact with it. Further reason for care is found in the fact that the mouth in an unclean condition becomes 2i favorable habitat for the development of fjerms some of which may have pathogenic properties capable of affecting the general health. It therefore becomes the duty of the dental adviser to enforce correct hygienic conditions of the mouth. Treatment of the Mucous Surfaces. When the gums, the membrane of the mouth or of the throat are inflamed, treatment preparatory to operations upon the teeth should be directed toward restoring these parts to a normal state. Where the inflammatory condition is not expressive of derangement of the alimen- tary functions and is the result of some simple local irritation, the condition will usually respond to the topical action of stimulant tonics. It is necessary here to discriminate as to whether or not the inflamed surface has been produced by neglected care of the mouth, which fre- quently induces a lax condition of the gum from the absence of friction or by the presence of bacteria. These may cause a deficiency of tone or disorders in other portions of the mouth and of the throat. Should these conditions be present the employment of disinfectant gargles and mouth-washes is indicated. The presence of salivary calculus may also induce inflammatory dis- turbance of the gums, and from the points of deposit this may extend by diffusion over a considerable area. In this connection deposits, either calculus or sedimentary accimiulations, posterior to the lower third molars may induce serious diffuse inflammation of the contigu- ous tissues, sometimes extending to the fauces. For this condition the mechanical removal of the deposits combined with an antiseptic spray will usually be restorative. For diffuse redness and deficient tone of the mucous surfaces a wash composed of potassium chlorate and quinia will prove sufficient in most cases, as follows : ^. Potassii chloras, Sij ; Quininse sulphas, gr. iij ; Sp. rectificatus, Sj ; Aquse, ^vj. — M. S. For use as a gargle. A dessertspoonful to a wineglass of water, or directly upcjn the gum of full strength by means of a soft tooth-brush. CAVITIES Ox\ APPROXniAL SURFACES. 103 Concurrently with the local therapeusis the employment of massage of the gum with the finger, either naked or covered with a napkin, is of considerable value. When the conditions are catarrhal or are expressive of gastric derangement only general treatment with concurrent attention to the diet and correct hygienic relations will meet the requirements of the case. Coincident with the general treatment above indicated, the simpler operations upon occlusal surfaces may be carried on. In all cases of initial treatment for children or nervous patients it is important to begin with simple and, as nearly as may be, painless operations, to accustom such patients to the more or less disagreeable procedures and to elicit their interest and co-operation in what is being done for their benefit. Cavities on Approximal Surfaces. The preliminary treatment of this class of cases, on account of the limitation of space and the necessity for somewhat indirect application of the instruments and of the requisite force necessitates the closest attention to every detail. Upon the care here taken depends the comfort, and furthermore, indirectly in many instances, the health of the person. The procedure of first importance is to produce a sufficient enlarge- ment of the interproximal space. In all cases, whether the teeth are in apparent contact or whether they may, from loss of substance on the approximal aspect, present sufficient room for the management of the various procedures, spacing is equally necessary. It is done in order that when the stopping procedures shall have been completed the natural relations of the teeth with each other will be restored. This relation, as before indicated, is one of apparent contact near the occlusal surface with a triangular space at the cervix. The mechanical basis of this arrangement is such that the function of comminution of food is better effected if there is no breach in the continuity of the occlusal aspect of the denture. The consequences of breaches of continuity, especially in relation to the posterior teeth, are often of serious import. Xot only may the food be driven into the space, to the discomfort of the patient, but serious injury of the gum may follow, as in many cases the tissue becomes inflamed by the impaction of food in the enlarged interspace, which in- duces peridental disturbances and may occasion the ultimate loss of the affected tooth. It is also not unimportant to consider that the forms of the teeth have an esthetic value, and that the harmony of the features forbids the mutilation of their natural forms. 104 PRELIMINARY PREPARATION OF THE TEETH. Separation of the Teeth. Separation of the teeth is a procedure requiring care to avoid injury and to render the process comparatively painless. When the teeth are mobile, as in the case of children, the movement is more easily and more quickly made than when the alveolar walls are compact and when also the teeth are in close proximity. In the former case the arch easily expands and permits the teeth to yield ; in the other case the resistance requires more force to be used and the application of it for a longer period. In all instances the force and the material used should be adapted to the presented conditions and the movement should be sustained until the required space is gained, it being dele- terious to make repeated attempts to separate the same pair of teeth. When the proper precautions are taken there is no danger attending the process ; even the firmest structures of mature age permit sufficient spacing if it be slowly and steadil}' done. METHODS OF MAKING SEPARATIONS. The means by which these are effected are various and the choice is determined by the amount of space required, the time in which it must be accomplished, and the firmness of the supporting structures. Some regard must also be had for the peculiar susceptibilities of the patient to the pain which may be caused by the effort. These methods are — by immediate wedging, which may be made when the fixation of the teeth is not firm ; by the swelling of firmly impacted pellets of cotton or of tape, and by the resilience of strips of caoutchouc where the teeth are in general contact and Avhere they are firmly fixed. Immediate wedging is more applicable to the front teeth, where usually only a small space is required, and is a valuable method of securing a separation of the front teeth to determine their condition and to permit i)olishing strips to be inserted for the removal of super- ficial discolorations and for the treatment of superficial softening. Here the procedure is to insert a wooden wedge between the incisors near the incisive edge, when it is forced by pressure or by percussion until a suf- ficient opening is efFectcd, the space then being secured by another wedge of hard close-grained wood forced between the teeth at the cervix. This process in some instances is repeated by forcing farther the first wedge and again increasing the security by driving the cervical wedge. This plan is not applicable when the interspace at the neck is quite angular, since the fixing wedge cannot be made secure, as it then is disposed to advance against the gum. In this case some of the subsequent methods should be pursued. If the fixation of the teeth be not firm they yield by a slight enlarge- ment of the arch and by closing the neighboring slight sj^aces. SEPARATION OF THE TEETH. 105 Immediate separations may be eifected by mechanical separators, notably the ^Yilliam A. Woodward (see Fig. 80) for the front teeth and Fig. 80. Fig. 81. Wood\¥ard's separator. Perry's separator in conjoint use with matrix. the Perry (see Fig. 81) for the bicuspids and molars. It should be stated that each of these is preferably to be used when some previous space has been made by other means, following which a considerable increase of space may be secured by these appliances. Separation by the Swelling- of Fibrous Materials. — These act by the capillary force of water upon the fibrous structure of the material, whether it be of cotton or tape. This means is also more applicable when the fixation of the teeth is not firm, and has the advantage of being painless and more readily tolerated by children and by persons who are impatient of pain or of any form of dental distress. Pledgets of cotton are more applicable where a partial preliminary opening of a carious cavity has been made, and are more appropriate for the posterior teeth. Here, when there is no danger of pulp exposure, the pledgets may be packed with considerable firmness. In some instances it is advantageous to saturate the pledget with thin sandarac varnish, which attaches the fibers, but the time required is much in- creased, as the cotton yields to capillary attraction only as it loses the resin. Tape is more useful for the incisors ; it should be of linen and may or may not be waxed. Its entrance is facilitated by an immediate pre- liminary application of a wooden wedge. Caoutchouc — India-rubber. — When a strip of india-rubber is drawn into a close interspace the middle portion is constricted to great tenuity. The action is by the resilience determining the two exposed ends toward the middle, with the result that at length the space attains the size of the thickness of the strip. It will be perceived that the physical force is that of two opposed wedges acting with constant power. The effect is such that it overcomes the greatest resistance to separation of the parts and therefore is the most effective means which we have. Caution is required in the use of this material both as to the thick- 106 PRELIMINARY PREPARATION OF THE TEETH. iiess of the rubber and as to its purity. The pronounced resilience of pure rubber is generally painful and in most instances too greatly so. The force can be reduced by employing specimens of the material adul- terated to reduce the activity of the resilience. The Avhite-rubber tubing: of the shops cut longitudinally into various widths as used effects the object with less rapidity but surely, and generally without pain. The strip is drawn into position by a sliding motion, care being taken not to force the piece into contact with the gum. To prevent the rubber being conveyed to the gum as the space enlarges, a small portion should ex- tend slightly beyond the occlusal surface. As this kind of rubber is more difficult to introduce when the contact is close and firm, a previous partial opening should be made with a piece of rubber dam. This method has the value of painlessness, and also does not necessitate a period of rest after the separation has been eflPectod. Red Base-plate Gutta-percha. — When it is desirable to gradually effect considerable spacing between teeth, where the carious cavities are deep with well-defined boundaries but not involving the pulp, the method of Dr. Bonwill, of packing the cavities and the existing space with a sufficient mass of this form of gutta-percha, produces expansion by the continued force of mastication driving the material upward. This method also has value in some instances where it is desired to force the gum beyond the cervical margins, and may be an acceptable sub- stitute for aseptic cotton for this purpose. Securement of the Space. — Should soreness of the teeth have been caused by the separation, a period of rest should be given the parts until the distress has passed over. It is, however, important that large spaces should not be long retained, since in some instances alveolar resorption may be induced by the continuation of the changed position. An inter- val of two days usually suffices for the pericementum to recover from the disturbance, when the restorative procedures may be conducted. The retention of the space may be effected with gutta-percha or with the plastic cemoits, — the first being suitable when an open cavity appears ; pho.spjhate of zinc when from the smallness of the cavity gutta- percha may not be readily retained. Oxi/chlorid of zinc should be used when the cavities are not deep but are sensitive, — the reason for which will appear later. It is generally advisable to introduce a thin wedge of wood at the cervix and in contact with the gum to prevent the re- taining material from imj)inging upon this tissue and to give a base to sup})ort the introducing force. Exposure of Cervical Margins. — "When cavities extend beneath the gum, which frecjuently is the case when caries has recurred above the cervical margins of fillings, it becomes necessary to force the gum somewhat al)ove the carious border. This should be done quickly SEPARATION OF THE TEETH. 107 rather than slowly, otherwise iu adult subjects the continued pressure may arouse diffused inflammatory disturbance of the contiguous tissues. Generally it is preferable first to cut away the gum between the teeth with a straight, narrow bistoury, and gently force red gutta-percha against the gum, gradually moulding it to the form of the depression. Cotton pellets for this purpose are not admissible unless they are anti- septically charged, for which purpose an admixture of aristol with the cotton is the most suitable, since not being soluble in water it better maintains the asepsis. Cotton may be conveniently charged with aris- tol by saturating it with a solution of aristol in chloroform and allow- ing the greater portion of the solvent to evaporate before introducing the pledget. When hyperseusitiveness of the gum tissues exists it is admissible to paralyze the sensation with a suitable solution of cocain, previous to introducing the pellet of either gutta-percha or cotton fiber. A four per cent, solution of cocain hydrochlorate applied upon cotton to the sensitive tissues will speedily relieve the condition. CHAPTER V. PRELIMINARY PREPARATION OF CAVITIES— TREATMENT OF HYPERSENSITIVE DENTIN BY SEDATIVES, OBTUND- ENTS, LOCAL AND GENERAL ANESTHETICS— STERILIZA- TION, WITH A BRIEF CONSIDERATION OF THE PHYSIO- LOGICAL AND THERAPEUTIC ACTION OF THE MEDICA- MENTS USED. By Louis Jack, D. D. S. Hypersensitive Dentin. Dentinal hypersensitiveness frequently presents the most serious impediment to the procedures connected with the treatment of dental caries. This condition must be considered an exaltation of the normal sensitiveness of the dentin, and presents a wide range from slight pain on contact being made to so high a degree of sensitiveness as to he un- endurable. In tlie latter instance persons of the greatest capacity for tolerating pain will shrink from the most careful instrumentation. Im- mediately upon the opening of a carious cavity there usually are mani- festations of excitement of the vital elements of the dentin. This con- dition may be so slight as to present no obstacle to further procedures, or it may on the other hand be so excessive as to forbid all instru- mentation until a reduction of the sensitiveness has l)een effected. This altered state of the dentin has been considered by some as one of inJiaiiiiiKdion of the dentin. As the opportunity does not exist for the usual concomitants of inflammation as pathologically defined and which are induced by the alterations of the circulation of the blood, viz. heat, redness and swelling, with exaltation of nervous function caused by the additional supjily of arterial blood, the term inflamma- tion is a questionable one to apply to a hyperesthetic condition of dentin. This manifestation is more logically explainable as a disturb- ance caused by changed relations of a tissue which is naturally pro- tected by the enamel from irritating influences. The relation of the enamel and the dentin is analogous to that of the epidermal coat of the skin and the rete mucosum. Pain caused by abrasion of tlie epidermis is immediate and acute, and occurs before tlie increased supply of blood increases the intensity of it. It is hence induced by 108 HYPERSENSITIVE DENTIN. 109 the altered relation of the mucosum. The analogy is further borne out by the fact that in each instance a protective covering aifords salu- tory relief. The normal sensitivity of dentin is not high, as is shown by an immediate examination of a surface exposed by accident, but after a few days the denuded surface manifests impatience of mechanical contact and of applications of cold, which proves that the altered rela- tions induce a condition of the part similar to the condition of the skin when the epidermis is broken. This appears to be the case in- dependent of the influence of chemical agencies, as exaltation of sensi- tiveness occurs when the fluids of the mouth are in a normal state. The same indications are presented when a non-sensitive cavity is j^re- pared, as here, in case the cavity be not protected by a stopping, the same phenomenon subsequently appears. Generally also, in such cases, if a stopping is inserted without pre- ^^iously eifecting a coagulation of the surface of the cavity, pain arises •upon reduction of temperature. This condition is designated as sec- ondary sensitivity. In some cases of this kind the pain becomes so great as to require the removal of the stopping and the carbolization of the cavity. In extreme cases reflected pain in the other teeth may appear in consequence of the disturbed relations making an impression upon the nervous elements of the pulp. When exposure of the dentin has been brought about by caries, the sensitivity excited is liable to be much exalted above the normal and is only prevented from giving constant indications of this condition by the presence of the carious matter, which, being a poor conductor of heat, in a measure protects the pulp from thermal irritation. This accounts for the fact that while there may sometimes be acute pain in the early stages of decay of dentin, the irritability appears to become less as the progress of the caries advances. When the teeth are undergoing rapid decay the dentin is more sen- sitive than when the carious process is slow. As the color of the carious matter gives some indication of the rate of progress, we may from this indication form an impression of the probable degree of sensitiveness. When the carious matter is light, the action has been rapid ; when it is yellow or light brown it is less active ; and when it is dark brown or black, it has progressed very slowly. In some cases of the last character, when the parts are subject to friction, spontaneous cessation of decay takes place. The parts are then devoid of sensi- tiveness. The process by which the dentinal tubuli become obliterated by calcific deposits is called eburnaUon. When the dentin becomes ex- posed by attrition or abrasion, that tissue is not as easily irritated as it is by the progress of caries, since by reason of the gradual approach 110 PEELIMISARY FBEPARATIOX Ut CAVITIES, ETC. changes take place within the tulinles In- which their capacity to convey sensation is diminished or obliterated as the case may be. ]]lien the gum recedes, exposing the cementum, a very high degree of sensitivity is often excited, which is prone to decline by spontaneous changes of structure. There is often here the added influence of acid conditions of the mucous secretions where they flow out upon the teeth at this point, and where, too, the parts are not easily cleansed. It is a notable fact in connection with cervical hypersensitiveness that while it persists these parts are less liable to decay than when loss of sensitive- ness here takes place. The area of hypersensitivity usually is not evenly distributed throughout the carious cavity, but has its chief seat near the line of union of the dentin with the enamel, thus bearing out the law that sensitivity is greatest at the terminal end-organs of the sensory nerves, with the further qualiflcation that the more minute the flbrillse the greater may be the acuteness of the sensitivity. This fact is illus- trated by the example of cavities in the occlusal surfaces of the molars, which manifest pain only at the margins ; is only less evident in the cavities of approximal surfaces, and is strongly shown in the shallow buccal and labial cavities, which present their whole surfaces near the juncture of enamel and dentin. In most cases of caries, the zone of highest sensitivity is hnmedicdely beneath the softened jjortion of the decay, and when this layer of dentin is cut awav the pain becomes less, in some instances approaching the nor- mal. This statement, however, has force only in the milder manifesta- tions of this condition. The Effect of Acid Conditions of the Oral Fluids. — In the pre- vious chapter some allusion was made to the fact that an acid state of the oral fluids is detrimental to the teeth as promoting carious action, and that alkaline or even neutral states have a retarding influence. Here it must be considered as an axiom that no cause is so active as a primary influence in inducing dentinal sensitivity as a constant, slightly acid state of these fluids ; and, conversely, that a neutral or slightly alkaline state is non-irritating. These conditions should be kept in constant view in dealing with this subject. The degree of sensitivity of dentin is modified by a variety of general conditions. These are the relative density of the structure, the rapidity of the carious action, and the constitutional peculiarities of the person, and are connected most directly with nervous impressionability to disturbances of the tissues. The rate of progress of caries exerts considerable modifying influence over dentinal sensitivity. When caries is of slow progress the amount of organic tissue exposed to irritation is comjxiratively small, for the HYPERSENSITIVE DENTIN. Ill reason that the well-known salutary and protective changes of structure go on coincidently with .the sIoav inroad. The slight irritation of slowly advancing caries to some extent exerts a stimulating influence toward inducing tubular deposits. On the other hand, when the cari- ous process progresses with rapidity the organic elements of the tissue are denuded and sensitivity is increased to a proportionate degree. As these fibrillar elements are the means of extending the irritation to the pulp of which they have the character of being prolongations, it is evident how important a factor the active advance of caries is, and also how much the rapidity of the process increases the morbid con- comitants of dental caries. In this case the irritation is so acute as to limit or prevent the tubular consolidation alluded to. It has been pointed out that the area of hypersensitiveness generally pertains to a narrow line at the outer limit of the dentin, but in rapid caries this line is a broader one. The anatomical element of the dentin concerned with its sensi- tivity is contained mthin the tubuli. While the exact nature of the matter in these tubules has not yet been certainly determined, it has been shown to have sufficient consistence to permit of extension, as in separating sections under the microscope what appear to be fibers have been seen. Also the same appearance has been presented in fresh specimens when the pulp has been drawn away from the dentin. It is not difficult in reviewing these facts in connection with the various conditions and phases of dentinal sensitivity to conclude that the exalta- tion is inseparably connected with an irritated state of the tubular con- tents. The variation in the degree of sensitivity of different teeth of the same mouth — of those which are side by side and in a similar degree of progress of carious action ; the profound fact, heretofore stated^ that the dentin at a short distance beneath the decay is much less sen- sitive ; that in some instances sedatives modify the degree of pain, and that coagulants produce a marked impression upon the capacity of the tubular contents to convey sensation, force by inference the conclusion that in diseased conditions this anatomical element is largely concerned in conveying impressions to the central organ of the tooth. It is also undoubted that unusually high sensitivity of dentin is an inherent constitutional condition with some persons, and that it pertains to some families apparently as an inheritance, but may be explained in these instances as the transmission of acute nervous impressionability. In connection with this subject should be considered the further observation that the temperature sense of the teeth is varied ; that with some the application of ice makes no impression upon the teeth when in normal condition, while with others in the same condition the least cold is painful. It would further appear that the degree of sensitivity 112 PRELIMINARY PREPARATION OF CAVITIES, ETC. when caries occurs bears some relation to the relative tolerance of the teeth to reduction of temperature. On these premises it is not difficult to account for the manifestation of acute sensitivity, and to build thereon an hypothesis governing the various conditions presented by dentin when it is subjected to the irri- tation of the carious process. These views have steadily gained sup- port with the advance of microscopic study of the tissues, and have supplanted the older view that the sensitivity of dentin is a result of vibrations extending to the dental pulp. Treatment of Hypersensitivity of the Dentin. Having considered the general principles governing hypersensitivity of dentin, we are prepared to enter upon a study of the treatment. This is to be considered under the following general lines : namely, the therapeutic, the chemical, the anesthetic, and the mechanical. Treatment of Slig-ht Hypersensitivity. — The first requisites to be observed here are a calm manner and earnest sympathy, accompanied with the assurance that if severity of pain occurs, mitigated means will be resorted to. It is an important and laudable object to remove dread and secure confidence, which is attained among other means by select- ing at first the simpler and less painful operations. When confidence is secured, slight pain arouses the courage of the patient. The effect of the opposite course of indifference and harsh cutting alarms the patient, arouses apprehension, and greatly increases the nervous exaltation. In the simpler cases sharp instruments used with quick, light, and rapid movements are called for. It should in this connection be noted that cutting in this manner stimulates somewhat the nervous force of the patient, and if the movements are in very quick succession they appear to paralyze the part ; the pain is thus lessened in comparison with deliberate and slow instrumentation. The movements of the ex- cavators should be in a direction away from the l)ul}) rather than toward it, and the cuts should l)e by drawing the points instead of pushing them ; this is for the reason that the pressure in the latter case is greater than in the former. When the sensitiveness is so great as to interdict immediate excava- tion and formation of the cavity, some method of treatment of the sur- face is reipiircd to overcome or to diminish it within a tolerable degree. The Therapeutic Treatment. — Under this head the available reme- dies are morphia, veratria, and cocain, — each of them })eing applied with glycerin as a menstruum. It should be stated that neither have nuich innnediate effect, and therefi)re they should be sealed in the cavity after the o])ening in the cniiincl lias l)een ])re])ared, and the softer caries has been lifted and peeled off. The closure should be effected by DENTINAL ANESTHESIA BY ELECTRICAL OSMOSIS. 113 means of gutta-percha, or with what is probably better, a thin paste of phosphate of zinc laid over the dressing. After some days the pain will be found diminished in many instances. The therapeusis is eifected by the absorption of these sedatives by the partially disorganized tissues. It is advantageous as preparatory to this line of treatment to first neu- tralize the acidity of the cavity with an alkaline solution, which may be either ammonia, sodium carbonate, or sodium dioxid. Treatment of Hypersensitivity of Dentin by ElectrIcal Osmosis. Within a recent period a means of treatment of this condition has become prevalent which has been designated by the terms cata- PHOEESis, electrical DIFFUSION, and electrical osmosis. It has been demonstrated that the action of electrical currents conveys fluids, with the substances held in solution, from the positive elec- trode toward the negative electrode. Further, that an electrical current passing through a membrane accelerates the natural process of osmotic diffusion if the positive pole is applied on the side of a membrane or tissue from which the osmotic diffusion is taking place ; in case the situation of the poles be reversed, the osmosis is retarded or prevented from occurrence or is reversed. This action bears some analogy to that which takes place in electro-metallurgy when a metal in solution is conveyed from the anode (positive pole), and is deposited upon the cathode (negative pole). If the current be reversed the de- posited metal is again taken up by the solution and is conveyed back again to the other pole. This is a law connected with the passage of electrical currents through fluids which are capable of conduction. The following will illustrate the action which takes place : " If two compartments separated by a membrane are filled with a fluid and in each an electrode is placed, there is a streaming of the fluid through the septum from the positive to the negative pole, so that in time there is an increase in the negative side. This osmotic action, as is M'ell known, occurs naturally between two fluids of unequal density from the lighter to the denser liquid, but if the anode is placed in the denser liquid and the cathode in the lighter the natural osmotic current is not only overcome but is reversed." This then is an expression of electrical force. The application of this law of the passage of fluids from a higher to a lower electrical potential is the fundamental process which is employed in electrical diff'usion of medicaments. The depth to which medicaments may be conveyed depends upon the conductivity of the tissue and that of the medicament which is being applied. " The cataphoric action of electricity has often been made use of 114 PEELIMIXARY PREPARATION OF CAVITIES, ETC. experimentally to introduce drugs into the system through the skin. In man quinia and potassium iodid have been thus introduced and subsequently been detected in the urine." As early as 1859 Dr. B. AV. Richardson used this process to pro- duce local anesthesia, and completely demonstrated its power in this direction. It has also been clearly proven that when a solution of cocain is applied to the skin, its characteristic action upon the mucous membrane will not here take place. But when the anode is wet with the solution and a galvanic current is passed through the part to the cathode, placed upon an indiiferent surface, anesthesia is effected over the surface covered by the anode and to an indefinite distance in- ward. This effect is not produced by the current alone, wdiich has been abundantly proven by experiments that demonstrate that the galvanic current has the ability to carry into the tissues with it such medicaments as may be applied. When the medicaments so applied have anesthetic or analgesic properties their characteristic effects are produced. When this principle is applied to the transfer of medicaments it is found that they pass for an indefinite distance into the contiguous tissue along with the current from the anode toward the cathode, but with some degree of diffusion ; the diffusion depending upon the resistance of the tissue and upon the extent of the surface of the cathodal (nega- tive) electrode. GENERAL PEINCIPLES INVOLVED IN THE METHOD. The application of electricity requires the consideration of the general principles or laws governing its transmission. The source of this force is to be found in chemical transformation. Under the laws of the correlation of force it is capable of being con- verted into heat, light, magnetism, and mechanical power, and may be used to disorganize substances, when its action is called electrolysis. Its movements are constant in their direction, viz. from bodies of high to those of low potentiality. In perfectly conducting substances electricity moves with perfect freedom under any electro-motive force however small. In perfect non- conducting substances electricity will not move under any electro-motive force however great. In imperfectly conducting substances electricity moves only on the exhibition of intense electro-motive force, the force varying according as the substance is more or less a conductor. The active energy of electricity resides in a property^designated its current strength, and termed its amperage. The pressure is the force required to move the amperage against the resistance of imperfectly con- ducting substances, and is termed voltage. DENTINAL ANESTHESIA BY ELECTRICAL OSMOSIS. 115 The unit of strength is the ampere. The unit of j^ressure is the volt. The unit of resistance is the OHM. The unit of power is the watt. A VOLT represents the electro-motive force (E. M. F.) recjuired to impel one ampere of current through one ohm of resistance. An amp£;re of current is so much as will deposit 0.00118 gram of silver per second when passing through a standard solution of nitrate of silver — or which will decompose 0.09326 milligram of water in one second. Hence the ampere is the measure of rate of flow of an electri- cal current, and in connection with the voltage measures the energy of the current. The unit of resistance (ohm) is that degree of resistance which will permit the passage of one ampere of current at one volt of pressure. The WATT is the power exerted by one ampere of current at one volt of pressure. In the economic application of electricity its transmission is effected through metallic conductors. The resistance of these is varied by the character of the metal, the cross section, and the distance. For certain purposes other substances are employed to effect greater resistance than the metals. The current strength flowing in a circuit is equal to the pressure divided by the resistance. The resistance equals the pressure divided by the strength. The pressure equals the strength multiplied by the resistance. In elementary terms : Amperes = volts -^- ohms. Ohms = volts -^ amperes. Volts = amperes X ohms. Watts = volts X amperes. It follows from the formula that the amount of power and the cost of producing it is the same whether the current is of large amperage at low voltage or of small amperage at high voltage. Thus an' incandes- cent lamp may be supplied by 100 volts at i ampere or by 50 volts at 1 ampere — the result in each case being 50 watts. Electrical force may be produced from its source in galvanic cells by arranging them in series or in multiple. If in series the voltage is the sum of the volts of the cells so arranged, and the amperage is that of each of the cells. If joined in multiple the strength in amperes is the sum of the amperes of the cells, and the voltage is that of one cell. 116 PRELIMINARY PREPARATION OF CAVITIES, ETC. Fig. 82 ' represents the arranging of cells in series, the positive of one with the negative of the next. In case each cell has a voltage of Fig. 82. + a. ^ 2 and an amperage of 1 the electro-motive force of 5 cells will be 10 volt.-^ at 1 ampere. Fig. 83" represents the joining of cells in multiple. Here all the Fig. 83. positive elements are joined together and similarly all the negative to each otlicr. The voltage now is 2 and the amperage 5. The former method of assembling the cells is designated as ''high tension," the latter method as " low tension." When the source is the dynamo, high and low tension are produced by the strength or weakness of the magnetic field. For electrical osmosis the source should be from batteries in series, for the reason that in multiple the amperage would be too great when the voltao;e is of sufficient force to overcome the resistance. The degree of electrical energy tolerated by living dentin is exceed- ingly small, on account of the peculiar and intense pain excited by the transmission of electrical currents through the teeth. This is shown by the low initial voltage of the batteries u.>^ed for the purj)o.^e, varying from less tlian 5 to rarely more than 20. But tlie initial j)a.ssage of a current of as liigh electro-motive force as these would not be tolerable, and must tlicrcfore ])e r('diic<'(l bv suitMl)h' mctliods of effi?cting re- sistance. 1 See DenUtl Cosmos, December, 1S9(), p. 998. ■' Ibid. DENTINAL ANESTHESIA BY ELECTRICAL OSMOSIS 117 The apparatus used for this purpose is the controller, the purpose of which is through the resistance to diminish the energy of the current to sufficient weakness to meet the requirements of any given case. All forms are constructed on the principle of the use of materials which are highly resistant of the passage of electric currents. These substances are water, carbon, graphite, and coils of wire of known high resistance, the most effective being of German silver. In the case of the latter the degree of resistance is regulated by the length and fineness of the wire, the cross section being reduced to the size which will conduct the cur- rent without excessive heating, and to that end it is graded with refer- ence to the initial amperage of the current. In comparison with silver as a unit German silver has a resistance of 13.92. In the water rheostat one pole is placed in the bottom of a small column of water. The other is attached to a sliding rod. The current passes through the battery, the water, and the patient in series, and is regulated by varying the distance between the two poles of the column. The carbon and graphite controllers usually are constructed in the form of a broken ring — one pole of the battery being connected at one end of the ring, the other pole being attached to an index which travels over this annular disk. This method of construction gives a fine grada- tion of current with high resistance. It may be used in connection with a German-silver wire rheostat, where currents of great strength are used for reasons which will appear later. In the use of high-voltage cur- rents, such as the 110-volt circuit, it may be switched through the coils to a nearly definite low voltage by means of the rheostat, when the adaptation to the case may be effected through the graphite controller. Fig. 84. In the arrangement of the apparatus to effect electrical osmosis the battery, the controller, the instruments of observation, and the patient are in series. In the analysis of the course of the current it appears that the patient is another element of resistance, and that dentin is more highly resistant than the other tissues. In other words, there are two resistances in the circuit — the controller and the tissues of the patient. The result of the resistance of the dentin, unless the initial voltage is 118 PRELIMINARY PREPARATION OF CAVITIES, ETC. small and is reduced by the controller to an infinitesimal degree, is the occurrence of })ain which takes place with diilerent |)ersons at various degrees of tension. The indications are that this pain is caused l)y the evolution of heat in the dentin, induced by the resistance of this struc- ture — heat l)eing one of the inevital)le consequences of electrical resist- ance. The variation in the occurrence and the degree of pain mav be referable to the difference in individuals as to tolerance of irritation caused by thermal shock. Another consideration connected with this kind of electrical irrita- tion is that the course of the current through the dentin is short at very high resistance, as wdll later appear, and therefore the same kind of im- pulse which forces the current through the resistant film in an incandes- cent lamp may here produce the pain manifested. The fact that in some cases the very lowest initial voltage must be selected to avoid the irrita- tion that a greater number of cells produce would a})pear to bear out the above hypothesis. The pain limit as indicated is variable with different persons, and with different teeth for the same person. With some it is reached with the first influx of the current at low voltage with a record of -^ milli- ampere, this low record indicating high resistance of dentin and ])er- mitting but slow increase of the force until after cocain has diminished the sensibility of the irritated surface. With others the pain limit may not be reached Avith an initial voltage of 20 and a recorded amperage of ^ to -^Q milliampere. In respect of electrical irritation there must be taken into account also the high nervous sensibility of some persons, as with these there usually appears greater susceptibility to electrical irri- tation. In this connection consideration should be given to the fact that the dentin is an electrolyte, and therefore capable of disorganization. The following table of calculated resistances shows the resistance in ohms, and makes it a})pear how considerable is the liability to the generation of heat in the dental tissues in view of their density, and shduld imjH'ess caution as to the care to be used in the application of electrical force for the purpose under consideration. With 15 volts initial pressure at y^ milliampere in circuit the ohms are 37,500. " 15 " " iV " " " 150,000. " 10 " " 1% " " " 25,000. " 10 " " yV " " " 100,000. " 5 " " y4^ " " " 12,500. " 5 " " iV " " " 50,000. As the resistance of the body including the dental ti.ssues varies from 10,000 to almost 70,000 ohms, it woidd ap]icar necessary that the con- troller should have at the highest ])oint a resistance of 100,000 ohms. DENTINAL ANESTHESIA BY ELECTRICAL OSMOSIS. 119 The varying resistance of the current through the tissues depends upon the density of the dentin, the distance traversed, the condition of the surface of the skin, and the thickness of the adipose tissues. The average resistance of the patient as recorded by Dr. W. A. Price is about 25,000 ohms from cavity to hand, and the difference of resistance from tooth to hand and cheek to hand is from 3000 to 5000 ohms. He reports one case where the resistance from cavity to hand with a 40 per cent, solution of cocain was 28,500 ohms, which on placing the pad on the cheek was reduced to 23,000 ohms. Dr. Price further pkices the average resistance from hand to tongue at 9000 ohms, and from cheek to tongue at from 3000 to 7000. This would make the resistance of the dentin nearly 20,000 ohms. An exact determination of the resistance of the skin in any given case would enable a very close approximation for the dentin to be calculated. The condition of the cavity as to relative moisture and the degree of saturation of the pledget of cotton containing the anesthetizing agent as well as the percentage of the medicament exert a considerable quali- fying control of the resistance, as appears from the experiments of Dr. Price. When a section of dentin partially dry on the surface had a resistance of 30,000 ohms, after being dried and saturated with a 40 per cent, solution of cocain the resistance was reduced to 4500 ohms. The principles here stated and the facts presented apparently demon- strate the importance of careful selection of the degree of initial voltage of the current ; of the use of a relatively low amperage to the voltage ; of the necessity of controlling the current within the boundary of the pain limit ; of the importance of avoiding impulses of current by rapid advancement or by movements of or displacements of the anode ; and of attention to the maintenance of a constantly moist state of the anodal and cathodal contacts. These principles and facts have led to the application of galvanic currents for the production of a state of anesthesia of hypersensitive dentin ; and the results of experimentation in this direction have proven that the same effects have followed here as have occurred in the softer tissues. The extreme sensitiveness of the teeth to electrical currents and their resistance to the passage of electrical force were obstacles to the earlier application of this method of treatment in dentistry. The absence of means to control the current strength (the amperage) and to reduce the pressure (the voltage) to the capacity of the teeth prevented experi- mentation in this direction until within a recent period. The degree of amphxige at short circuit that is tolerated by the teeth is usually less than four milliamperes, which at the commencement of the application of the current is scarcely measurable. As the pres- 120 PRELIMINARY PREPARATION OF CAVITIES, ETC. sure of the current is increased the effects are produced within a recorded strength of three-tenths of a millianipere. The voltage pressure tolerable at first is equally small in proportion. It follows, therefore, that the apparatus to be employed in the administration must be capable of con- trolling both these properties of the electrical force. Any form of battery which is constant when the amperage of the individual cell is from one-fourth to five-eighths of an ampere will have sufiicient current strength. The potentiality may be from one to two volts per cell. The voltage required to produce the necessary electro-motive force in the application to the teeth to produce dentinal anesthesia varies from five to thirty. For children and where the teeth are apparently not dense, ten cells sometimes are sufficient, but generally fifteen to twenty are needed. The cells should be connected in a manner which enables the selection of any given number required to produce the required E. M. F. for any given case and to permit an increase of cells during the administration. The most important condition of the electrical force for the purpose is that the amperage shall be inconsiderable, since high amperage is intol- erable to the teeth. As the most efficient results are produced when the amperage at short circuit is rarely over three milliamperes, the use of a current of high amperage is unnecessary and is attended by distress. Equally so is high voltage painfnl, as the endeavor to force the current against the resistance of the dentin results in the evolution of heat. The influence of this when too high is a cause of pain, since the teeth are very sensitive to alterations of temperature above the normal. The j)rinciples governing the evolution of heat when electrical energy is forced against the resistance of a poor conducting medium explain the necessity for caution in the management of the circuit. The resistance of the dental tissues is evident from the fact that M'hen the circuit is being made through the caries and the dentin, the milliamperemeter rarely records more than three-tenths of a milliani- pere. The result, therefore, of the application of nnnecessary force in- duces some elevation of temperature, which is diffused through the adja- cent tissues and is modified by evaporation of the aqueous solution. The chlorid of silver cell is probably the one best suited for the purpose, as its electro-motive force remains practically constant under various conditions. The E. M. F. of each cell is about one volt ; the internal resistance eight ohms ; the strength one-fourth of an ampere. This battery on account of its constancy and durability is largely used in electro-medical apparatus. It is now furnished dry, and is more acceptable as being less troublesome on this account. The dry Leclanche battery is also one of the best forms, as it is an DENTINAL ANESTHESIA BY ELECTRICAL OSMOSIS. 121 open-circuit battery. As long as the circuit is open there is no action in the cell and consequently there is no loss. At present these two forms of galvanic battery cell appear to be the kinds best adapted for the purpose of inducing electrical osmosis. The storage battery may also be used with advantage, but the plates should be small ; each cell should contain but three plates to give the proper degree of current strength. When the plates are 3x3 inches the normal amperage at eight hours' discharge is five-eighths of an ampere. The voltage of each cell is two. This when discharged under the resistance required for application to sensitive dentin in cataphoric work should have a capacity for 800 applications, providing waste of current streno-th does not occur from accidental short-circuiting. The life of a chlorid of silver dry cell battery is stated to be 700 hours of cataphoric work under a high resistance of tissue, but it must be remembered that the continuance of energy of all forms of battery is varied by the resistance and the conversion of electrical energy into heat by the controller which regulates the amperage and the voltage. This principle applies to all sources of electrical force. The controller which at present appears best adapted to be interposed between the battery and the anode is the Willms Controller, which has a very high internal resistance, stated to be 90,000 ohms at the point of greatest resistance. The gradations of resistance decrease from this through 112 contact points. These permit a very gradual reduction of the resistance as the switch is conveyed from point to point in the circle. This controller also has the advantage of being of moderate cost and easily procurable. An important adjunct of any apparatus is a reliable milliamperemeter. This should have a scale to record divisions of twentieths of a milliampere. This appears necessary from the fact that the amperage of the current through the dentin is frequently efficient at less than two-tenths of a milliampere. The milliamperemeter also aids in detecting leakage of current, as where the indicated amperage exceeds five-tenths milliampere there is reason to suspect imperfection of the insulation of the tooth. In this case a longer period than usual will be required to effect the anesthetization, and the degree of this effect may be less. The use of the direct current of 110 volts or higher generated by the dynamo is of questionable utility as compared with the current from a battery. The dynamo has not as yet been sufficiently perfected to produce a perfectly steady and uniform flow of definite voltage. The unevenness of pressure produces a series of pulsating shocks upon the sensitive dentinal fibrillse which react as pain. The possibility of the transmission of severe shock through accident or defective apparatus where such excessive voltage is used is another and sufficient reason 122 PRELIMIXAEY PREPARATIOX OF CAIVTIES, ETC. Avhv the steady and low-voltage current of a battery is preferable for this class of operations. TECHNIQUE OF THE AD]\riNISTRATION. At the present period cocain has been found to be the most efifective anesthetic for obtunding dentinal sensitivity by electrical osmosis. It is used in strength varying from 12 to 24 per cent., and by some as high as 40 per cent, has been used ; li grain of one of the salts of cocain added to 5 minims of Avater procures a solution of 24 per cent. ; to 7^ minims, 18 per cent. ; to 10 minims, 12 per cent. The salts of cocain which have been under experiment are the hi/drochlorid and the citrate. Each is efficient in the strength stated. The rate of conductivity of these solutions for the electrical current has not been accurately determined. The indications are that the scale of solubilitv of the hvdroehlorid is slijrhtlv the hit>:her, tliouffh notwith- standing this fact, for reasons not at present apparent, the citrate has greater power when applied to dense tissue. The tooth to be operated upon is isolated by means of a rubber dam and is ligated at the cervix to prevent leakage of current. If there are metallic fillings in the tooth, these should be covered with a coat of varnish carefully laid on. This precaution does not always possess the value claimed for it, as the dentin beneath a metal filling, because of its density, will not convey the current as well as the carious mat- ter and the softer dentin of the fresh cavity. In some cavities where caries has occurred at the cervix above gold fillings and which do not permit of complete isolation of the fillings, the cataphoric influence is not interfered with. The carious matter should not be removed and need only be partially dried on the surfiice. The cavity is loosely filled with a small pledget of lint saturated Avith the solution of cocain. The anode, the point of which is of platinum, is covered with a thin stratimi of lint which is dipped in the solution and inserted in the cavity in contact with the pledget previously introduced. The cathode, Avhich should be at least one and a half inches in diameter, is placed at a convenient place on the face or neck. The desired number of cells are placed in circuit with the controller at zero. All being ready, the switch is placed on the first contact point. At this moment, however great the resistance of the controller, a slight sensation is experienced, but at once the switch may be passed slowly over the contacts until some sign from the patient indicates that the current is being felt. Here it is retained until subsidence of the sensation occurs, when the resistance of the controller should be very gradually lessened. This process is continued, keeping constantly Avithin DENTINAL ANESTHESIA BY ELECTRICAL OSMOSIS. 123 the limits of pain ; at length the switch may be more rapidly advanced. When this can be done without thrill, the indication is that anesthesia is complete. The switch is then carried back to the zero point, when the excavation may be conducted. Where it is necessary to remove the rubber (as the solution of cocain is strong) the preparation should be previously washed away to prevent any of it from being swallowed. The period of administration varies from eight to fifteen minutes in ordinary cases. When, however, the dentin is dense, as where denudation has taken place by attrition, a longer time is required to effect penetration by the cocain. The sphere of the action extends throughout the cavity, but to a somewhat less degree at the extreme lateral margins, and more particu- larly at the occlusal margin. Here usually no more than a normal degree of sensitivity is found, which appears to be due to the fact that in making the retentive undercutting this procedure may extend beyond the sphere of the complete influence of the cocain. The effect is most pronounced when the application is made directly to the carious matter. In this case the diffusion is greater than when the caries is removed, for the reason that in the latter case the current seeks the line of least resistance toward the pulp. It follows from this that when all parts of the cavity are equidistant from the pulp, the action should be more effective throughout upon the surface of the dentin. This is proven to be the case from the profound effect in cavities upon buccal and labial surfaces and in shallow cavities of occlusal surfaces. Besides the less diffusion of the cocain when the carious matter is removed, a degree of electrical force which in the former case is easily tolerated becomes painful. These facts make conclusive the importance of retain- ing the carious contents of the cavity. Conditions Influencing Tolerance of the Current. — As already stated, when the current at fifteen or twenty volts is brought into connection with the carious matter, the irritation caused by the current is of trifling degree and soon so subsides as to give indication that the anesthetic effect has been produced, but when the cavity is denuded of caries the above degree of force of current is not so tolerable, the irritation con- tinues longer and does not subside in the same manner, but the effect upon the tissue is nearly, if not quite, as marked. The nearer the bottom of the cavity is to the pulp, the greater the irritation. This is probably due to the evolution of heat taking place in the dentin, whereas in the former case, the resistance being largely in the carious matter, the con- version of heat is at the superficies of the cavity. This irritation is the more pronounced in proportion to the proximity of the pulp. Hence in this condition it becomes necessary to commence with a less degree of 124 PRELIMINARY PREPARATION OF CAVITIES, ETC. Fig. 86. voltaije. AVhile in the one case fifteen cells may be selected, in the other ten cells are more satisfactory. To avoid the removal of the caries the condition of the dentin as regards sensitivity should be tested at the line of its connection with the enamel. Some stress has been laid upon the necessity for rendering the solution of cocaiu more highly conduc- tive. This claim is probably more theoretical than practical in its character, since experience with the solutions given indicates that the conductivity is suf- ficient, and that the resistance is more to be looked for in the dentin than in the solution, and that when the tooth has become tolerant of the current at a com- paratively low voltage, an increase of pressure of the current is sufficient to complete the anesthesia. The form of the platinum anode should be such as to permit its easy entrance into the cavity when its point is covered with a layer of absorbent lint. Two or three points to screw into a common handle of small size are all that are required. Fig. 85 shows a satis- FiG. 85. Liciital aiiu illustrates the Hollingsworth Syringe Electrode, a device by which the cocain solution is supplied at will to the pledget of lint in the cavity by depressing the piston of the electrode and forcing the contained solution out at the ori- fice of its tubular point. The supply of cocain solution in the cavity may thus be maintained without interrupt- ing the circuit by removal of the elec- trode. A convenient CATHODE ELEC- TRODE is shown in section in Fig. 87. In this the surface is recessed DENTINAL ANESTHESIA BY CHEMICAL AGENTS. 125 to receive a disk of amadou (spunk) or cottonoid, one and a half to two inches in diameter, which retains an abundance of a solution of sodium chlorid to maintain contact. The surface is platinized to pre- FiG. 8 Cathode for cataphoresis. vent corrosion. The reverse side has the usual socket to receive the conducting cord, which is placed in a projection intended to pass through an opening in the band which supports the rubber dam. When there is much adipose tissue on the face, the usual negative hand electrode, covered with a small wet napkin to maintain close con- tact, may be better than the application to the face, but in general the nearer the cathode is placed to the angle of the jaw, the quicker and surer is the result of the administration. This method of treatment is little required where the degree of liypersensitiveness is such as to yield to desiccation of the dentin or the application of carbolic acid combined wdth caustic potassa (" Robin- son's Remedy "). But when the pain attending excavation requires active treatment, such as the employment of zinc chlorid or general anesthesia, the cataphoric method is far preferable to either, and is absolutely certain of giving relief. The results of successful cata- phoresis are marvellous, and it may be truly stated that no advance of recent years in the therapeutic treatment of the teeth is comparable to this. The Chemical Treatment. Under this head are included the application of warmed air, the use of coagulants, notably carl>olic acid or zinc chlorid, and, in combi- nation with these, one of the essential oils, preferably oil of cloves, for reasons previously given. Warmed Air. — This method is of great value ; it is applicalile to cavities of easy access, and is especially serviceable for the cavities of incisors and bicuspids. The effect here produced is due to the depriva- tion of the tissue, to a greater or less degree, of one of its elements, viz. water, and it is more effective in teeth of dense structure, since the sur- face of these is more easily desiccated than the softer teeth. If it were possible to remove all the water of the tissue from the surface to the depth of the irritated part all sensitivity would thereby be overcome, but generally this can be only imperfectly done ; nevertheless, the Ijenefit is generally considerable. This means is easily and quickly applied, 126 PRELIMINARY PREPA RATIOS OF CAVITIES, ETC. and as it presents the simplest method in the cases where it is applicable it furras therefore the easiest and most available procedure lor this purpose. The warmed air is best produced by heating the liulb of a waem- AiE SYEIXGE (Fig. 88) over a lamp or Bunsen burner, when a continu- FiG. 88. Warm-air syringe. ous Stream of air is forced through the nozzle into the cavity. Some tact is required to deliver the heated air in a manner to cause the least pain bv its impingement. If the nozzle be held too far away from the tooth the stream of air in passing through the atmosphere takes along with it so much of the surrounding cool air as to cause pain, and if held too close the heat is equally painful. In all cases the abstraction of the water, even wlun xlw degree of heat i> will lialanced. produces some unpleasant sensation, which soon passes away and after a few moments the case is reduced to a state of slight and simple sensitiveness. The Fig. 89. Electric warm-air svrin-'t blast should be gently applied at first at intervals of a couple of sec- onds ; when the pain induced by the abstraction of the water some- what diminishes, the force should be increased and made continuous, when in most cases the excavation may be continued. The air may also and preferably be heated by an electric warm-air syringe (Fig. 89), which has the advantage of maintaining an even degree of heat. As stated before, this means is of less use with soft teeth, and fre- DENTINAL ANESTHESIA BY CHEMICAL AGENTS. 127 quently fails when the teeth have a high grade of sensitivity which appears to be due to constitutional conditions, — where the sensitivity is not confined to the surface of the tissues immediately beneath the caries but pertains to the whole of the dentin. Preparatory to the use of heated air, the application to the cavity of absolute alcohol is serviceable, on account of its high affinity for water. Carbolic Acid. — This substance, while of little efficiency in con- trolling acute sensitivity, is of service in moderating that condition. Its efficacy is increased by adding to it a proportion of one-third of oil of cloves, which latter has some anesthetic influence. When other more active means are not admissible and the effect is not immediately satisfactory, a .better result is produced by placing this combination in the cavity and sealing it in with zinc phosphate until a subsequent visit, as before described. On account of the feeble affinity of carbolic acid for water, the obtundent effect is facilitated by the previous partial desiccation of the surface of the cavity by warm-air blasts. Carbolic acid in combination with caustic potassa, equal parts of each (Robin- son's Remedy), is often of much service in subacute sensitivity. The preparation should be laid in the cavity in contact with the denuded dentin and should be allowed to remain until it deliquesces. Carbolic acid in combination with tannic acid is also serviceable when sealed in the cavity by an impermeable temporary stopping. Zinc Chlorid. — Of all substances, when not interdicted by proximity of the dental pulp, zinc chlorid is the most efficient of the topical remedies for the condition under consideration. Its action is explained by the double power of its affinity for water and its extreme coagulating effect upon albumin. It is evident that if the tissue be deprived of two of its elements the function of sensitivity must be impaired or destroyed. In the degree to which this action takes place the tissue loses its capacity for irritation. As zinc chlorid in concentrated solution is an active escharotic to organic tissue, it must be employed with caution. After paralyzing the vital resistance of the part its action is by combining in definite propor- tions with the albuminous elements of the structure. It has the further property of an excessive affinity for water, which permits of its action being terminated by sufficient irrigation to remove all traces of the salt from the cavity. Its active coagulating power renders it a valuable agent in excessive dentinal sensitivity where there is not close proximity of the pulp, and its safety is ensured by the facility with which any re- mains of the salt may be taken up with water. Unless employed in excess and too long continued the action of the zinc chlorid does not pass beyond the zone of the exalted tissue, which. 128 PRELIMINARY PREPARATION OF CAVITIES, ETC. as we are aware, is of limited depth. The cessation of the pain pro- duced by it indicates the time for its removal, when usually the dentin will be found to be insensitive. There are instances, however, when no apparent effect is produced, which can only be satisfactorily explained on the ground that the vital resistance of the tissue is sufficient to over- come the coagulative power of the zinc salt. In general, zinc chlorid must be regarded as an entirely safe agent if used with discrctiou. It is more applicable to shallow cavities which are so situated, or are of such form, as to require much formative cut- ting at the margins of the cavities, as in Ijuccal and labial surfaces and in the superficial cavities of incisors and bicuspids. A warning, however, should be presented that as the pulp cornua of incisors frequently pro- ject near the surface, particularly in the young subject, considerable care is here required in any but shallow cavities of decay. If it were used in excess and its action extended there would always be danger, as its enerp-ies would not cease until the affinities of the whole amount were satisfied. In deep cavities the effect, ]>articularly in soft teeth, would eventuate in the ultimate devitalization of the pulp. It fol- lows, therefore, that it would be improper to seal up any quantity of this substance in a cavity. The action of zinc chlorid is terminated when the excess is removed and the cavity irrigated with water. The affinity it has for water quickly removes the excess and soon deprives the tissue of the remain- ing portion. When cavities are deep and it is found necessary to resort to this agent the surface of the deeper parts may be protected by an insoluble coating, when the margins, where the sensitivity is acute, may be acted u})on without detriment. Here it is necessary to first remove the deep caries, desiccate the surfiice and make a coating with a varnish. For this purpose red gutta-percha rul)bed in chloroform is ap])lieal)le, since it may be deftly ajjplied to any given part and when the chloroform has escaped is protective. To properly apply zinc chlorid it is highly important to isolate the tooth by means of rubber dam to protect the gum and to prevent the entrance of moisture. Its affinities for water are so great that even the vapor of the mouth dilutes it so much as to lessen its power. The form in which it is best to employ it is the saturated deliquesced salt, which is taken from a bottle containing the salt in excess. The fluid is introduced on a pledget of cotton and is permitted to remain until the pain occasioned by it has ceased. It will be found that there are two periods of pain : tlie first from its irritation of the fibrils in the bottom layer of the caries, and then again when it has reached the zone of exalted dcntiu a little beneath this ultimate laver of decav. DENTINAL ANESTHESIA BY CHEMICAL AGENTS. 129 It follows, if the caries has all been previously removed and the sensitive tissue interdicts further cutting, that but one period of pain is encountered. The cutting should therefore be deferred until after the second period of pain has passed. The disregard of this considera- tion has sometimes cast discredit upon the efficiency of this sovereign remedy. It is requisite that the chlorid be chemically pure, and the fused form is preferable to the crystals of the shops. The PAix following the application is sometimes extreme for a mo- ment. This can be moderated by air-drying the cavity and dressing it with carbolic acid, which does not seem to prevent the action of the chlorid. To avoid the loss of time which may be occasioned by the slow action it is advisable, after securing the dam at the neck of the tooth by a ligature, to very tightly tie the free portion of the rubber a short distance from the tooth with a strong ligature, and after cutting away the excess of rubber some other service may be rendered. When the pain has ceased the case may be proceeded with, or the excess of chlorid may be thoroughly washed out and the cavity temporarily closed until a subsequent time. Another method of securing; the action of zinc chlorid is to make a paste of ziyic oxychlorid and fill the cavity with it. Even after crys- tallization of the paste takes place it contains a slight excess of the chlorid, which slowly acts upon the hypersensitive tissue. This method, however, is not adapted to deep cavities, and care must be exercised con- cerning its use in teeth of inferior grade. Zinc chlorid is an extremely valuable remedy when the previously described agents prove insufficient or are not indicated. Conditions which render Zinc Chlorid inadmissible. — It has been stated that the chief danger of its use consists in the liability of the coagulant and escharotic action reaching the pulp in deep cavities. This danger is further enhanced when the teeth are soft, as in this con- dition the penetration is liable to be greater than would be the case with dense 'dentin. The same caution must be observed when the structure is incomplete, as it is in the teeth of young subjects. Even here, as extreme sensitiveness is always found at the peripheral limits of the tubules, it is not difficult to limit the action to this part by the means above pointed out if care be taken in the required procedures. The Acids. — Chromic and nitric acids are of service in extremely shallow cavities of very high sensitivity. The former acts by coagulation of the organic elements of the dentin and the latter by decomposition and solution. To apply these the adjacent tissues require to be pro- tected. Each should be carried in small quantity upon a gold probe. 9 130 PRELIMINARY rREPARATION OF CAVITIES, ETC. Nitrate of silver is applicable for reducing the sensitivity of den- tin after the removal of superficial caries or when by abrasion or by erosion the exposed tissue is intolerably sensitive. It is, however, only to be used in the back of the mouth on account of the discoloration which it produces. General Anesthesia. While some reluctance should exist as to the propriety of inducing general anesthesia, it sometimes becomes necessary to resort to this means of alleviation. Necessity for this election arises when the sen- sitivity is extreme, when the previous remedies have been inefficient, and when from the nature of the case zinc chlorid is inadmissible. The subjects should generally be adult persons of intelligence, who possess moral force and, having confidence in their adviser, are capable of giving the requisite indications of the progress of the anesthetic influences. Sulfuric ether is the most suitable anesthetic to be employed, and the operative procedures should be performed in the first stage, that of peripheral anesthesia. At this period, which is before the stage of excitement commences, dentin may be cut without the slightest pain being felt. This is an important consideration, since if the ad- ministration is continued into the period of excitement nothing can be done, and if it is conducted to a full degree the patient is not manage- able. Also the subsequent depression is to be avoided. While general anesthesia in the first stages is available for the relief of dentinal sensi- tivity, it is found, on the contrary, when resorted to for the removal of the pulp, as may occasionally be required in the most severe cases of congestion, that nothing short of profound anesthesia will suffice. When the first stage is reached, the patient being conscious and able to reply to questions, the cutting is commenced ; as the pain returns a few more inhalations are given, when another part of the cutting may be proceeded with. This may be repeated until the cavity is formed. The cutting should be quickly and deftly conducted. The amount of ether administered is fiir less than is required to induce full anesthesia, and the patient suffers far less depression than if the operation were performed without this means. There is also no danger of shock, since the patient is, or should be, intelligently concerned in the progress of the case. If the condition were carried into the second stage, when excite- ment exists and alarm is aroused in addition to the operative interfer- ence, there is liability to shock, which, being due to a profound impres- sion on the nervous system, is not liable to occur when the patient concurs in all the steps of the procedure. The time required to bring about a sufficient degree of dentinal GENERAL ANESTHESIA. 131 Fig. 90. The Allis inhaler. anesthesia frequently is less than two minutes. The ether should be pure and should be given with a free supply of air mixed with the vapor. The ordinary custom of using the towel to envelop the face is questionable, since this method does not permit enough air to accompany the ether vapor. An invaluable inhaler for this purpose is the one invented Ijy Dr. Allis (Fig. 90). This consists of an oval frame composed of a series of wires through which passes back and forth a continuous band of muslin. The layers of muslin are near each other, and still so far apart as to permit the free passage of the at- mosphere. The correct manner is to continuously drop the ether in small quantity upon the muslin to maintain it at an even degree of saturation. This appliance is one of value to the dental operator, as by it the anesthetic state can be more quietly brought about with less of the characteristic disturb- ances which attend the usual modes of applying sulphuric ether. The use of chloroform for the purpose under discussion is wholly inadmissible. The mechanical means consist in the use of temporary fillings, which may be either metallic or non-metallic. The metallic act by inducing, in consequence of the slight irritation of thermal conductivity, a consolidation of the subjacent dentin, which in time obliterates the tubules. The non-metallic act simply as a protective covering to the denuded dentin. Their action hence is more tardy than that \^'hic•h follows the use of the former. The metallic stoppings for this purpose may be composed of either tin foil or amalgam. Each of these requires cavities of reasonably good retentiveness, therefore they are not applicable to shallow cavities of unsuitable form. The non-metallic may be either gutta-percha, zinc phosphate, or zinc oxychlorid. The tw^o latter are the most desirable, as they adhere to any well-dried cavity, and having some irritating influence on the tissues tend to induce structural consolidation in addition to their protective action. They have, however, the disadvantage of suffering loss by chemical solution, and unless kept under close observation are delusive and in many instances are a deceptive means of preventing the recurrence of decay. In the employment of these substances due care should be exercised concerning the proximity of the pulp, in which cases 132 PBELIMTXARY PREPARATION OF CAVITIES, ETC. the previously indicated means of shielding the pulj) walls should be pursued. The ehief dis(|ualitication of gutta-percha is its lack of resistance to attrition, and when in positicjus shielded from wear it may be attacked bv low forms of bacterial life, which disintegrate it. Mechanical ])rotection of cavities is most applicable to teeth of a low grade of structure and f )r young children who may not have the ability to tolerate the more active means needed to reduce dentinal sensitivity. For these cases gutta-percha stoppings when carefully introduced are a great boon, since they ])rotect the tissues during the period of completion and consolidation of the teeth. CHAPTER VI. PREPARATION OF CAVITIES— OPENING THE CAVITY— RE- MOVING THE DECAY— SHAPING THE CAVITY— CLASSI- FICATION OF CAVITIES. By S. H. Guilford, A. M., D. D. S., Ph. D. General Considerations. — The importance of the proper preparation of a cavity for the insertion of a filling can scarcely be overestimated. Upon its being well done the success of the completed operation largely depends. As many fillings fail from lack of thoroughness in the pre- paration of the cavity as from any other cause. The operator should not be actuated by haste, but should be deliber- ate, careful, and painstaking. Each stage of the operation should be thoroughly performed in order that when completed the cavity may be in the best possible condition for the reception and retention of the filling. The operation is naturally divided into three stages : 1. Opening the Cavity. 2. Removing the Decay. 3. Shaping the Cavity. Opening the Cavity. Every cavity to be excavated must first be opened, so that it may be approached and operated upon at all points. The particular manner of doing this will have to be determined by the extent of the decay and its position, but in all cases the opening must be as full and free as the conditions will permit. The accessibility of the cavity will depend upon its location. Upon the three exposed surfaces of a tooth crown (occlusal, lingual, and labial or buccal) access to a cavity is usually easy, but upon the unexposed surfaces (approximal) access can only be had after the teeth have been pressed apart. For methods of securing temporary separation of the teeth see Chapter IV. A cavity upon an exposed surface, if small, can usually best be opened by the use of some form of engine bur. A few sizes each of the forms known as " fissure," " inverted-cone," and " round " (or 133 134 PBEPABATIOX OF CAVITIES. " rose-hcad " ) arc sliown in Figs. 91, 92, and 93. A spear-pointed drill is sometimes used, but is less serviceable on account of its tendency to ])e caught or broken in the irregularities of the cavity orifice. A modified form of fissure bur has found much favor in the opening of small cavities on exposed surfaces. It is made from an ordinary bur Fig. SI]. Fig. 92. Fig. 93. II luvertL'd-L'uiiL- l.mi>. Ki-'Uud bui; from which the head has been broken, by cutting spiral blades on the tapering neck of the shank. Being pointed, round, and tapering it easily eifects an entrance into the cavity and enlarges the orifice grad- ually and symmetrically. It is shown in Fig. 94. In cavities of larger size, where decay has made more progress, the overhanging walls of enamel can best be l)n)ken down In' chisels of suitable size and form. AVhere a straight chisel can be employed it will l)e found most efficient, but in positions difficult of access those having a slight curve or angle may need to be employed. Figs. 95 and 9G rei>rescnt both forms as well as the sizes usually preferred. The Fig. 94. Fig. 95. Fig. 96. I Modified fissure bur with tapering point. Straight chisels. Curved chisels. width of the blade may vary from one-sixteenth to one-eighth of an inch, l)Ut wider ones than these will seldom be re<|uired. A chisel may be used with either hand pressure or mallet force. If the former, great care must be exercised to prevent its slipping and causing pain or possible injury. The best safeguard in its use is to place the thumb of the right hand on the tooth being operated upon or some adjoining one and use it as a fulcrum or pivot upon which the REMOVING THE DECAY. 135 instrument may move in a curve. By this means the motion of the chisel is regulated and controlled and all danger of slipping avoided. It will sometimes be of advantage to roughly pack the interior of the cavity with cotton or spunk to receive the impact of the instrument should the chisel accidentally be forced to the bottom of the cavity. The better plan, however, in most cases, is to employ mallet force for the cleavage of enamel unsupported by dentin. By holding the chisel between the thumb and three fingers of the left hand and resting the little finger of the same hand on an adjacent tooth for steadiness, a smart but light blow of a mallet in the right hand upon the end of the chisel will easily and painlessly cleave oif portions of the enamel. In opening cavities of small extent or limited depth upon approxi- mal surfaces a round or inverted-cone bur will best -p g-, serve the purpose, but where caries is more exten- sive and the surrounding enamel is unsupported by dentin the orifice of the cavity can be more advan- tageously enlarged by means of a delicate chisel (shown in Fig. 97) the blade of which is bent at a slight angle to the shank and all three of the edges of which are bevelled to convert them into cutting edges. This instrument will be found especially useful in opening cavities of medium or larger size on the approximal surfaces of the incisors, the ]3oint doing the cleaving and the side edges being used to Delicate three-sided smooth the enamel margins. S^rnt, cl'^'es » After the orifice of the cavity has been sufficiently approximal sur- enlarged to afford a full view of its interior the next stage of the operation is entered upon — Removing the Decay. The character or consistence of the carious structure has much to do with the method and means employed for its removal. If it be of the semi-elastic or leathery variety so often found in the teeth of young persons, it can be most easily removed by means of spoon-shaped, or round-bkided excavators, which being oval or circular in edge out- line and free from marginal angles, will lift and separate the layers without danger of injuring the underlying healthy dentin and with the infliction of a minimum amount of pain. Fig. 98 illustrates this kind of instrument in some of its forms, selected from the Darby-Perry set. In the darh, hard variety of caries, as also in the white, chalky variety, the different forms of burs and excavators will be found best suited for the purpose. In the removal of caries care should be exercised to inflict as little 136 PREPARATION OF CAVITIES. pain upon the patient as possible. To this end, in cavities of con- siderable extent, it is best, after the orifice has been sufficiently enlarged, to make a sweeping cut with an excavator around the cavity just below Fm. 98. n r/ M i i 1 i 1 n tj ( n r.j Excavators. the enamel line, thus freeing the decayed portion at that point. Follow- ing this the remaining portion of carious dentin should be removed by placing the l)lade of the excavator near the bottom of the cavity and makinof draw-cuts toward the orifice. To cut in the reverse direction would produce uncomfortable pressure upon the most tender portion of the cavitv, and possibly, by inadvertence, expose and wound the pulp. When bui's are employed for the removal of caries it is safest to use only such as are more or less rounded on their circumference, such as the round or oval forms, for they more nearly conform to the natural outline of the cavity, leave no angular grooves in the dentin difficult or impossible to perfectly fill, and are not so likely to injure the healthy subjacent dentin. The varieties of bur known as the inverted -cone and vheel, while very useful for opening cavities, should not be used for the removal of caries in deep cavities, because of the irregularities of surface which their peripheral angles jiroduce. Rapidly revolving burs in an engine handpiece are very apt to cause pain by the development of frictional heat. This may largely be pre- vented by lifting the bur at short intervals and allowing it to run free for a moment, which will prevent overheating the tooth and thus avoid unnecessary ])ain. Thorough excavation of the cavity and the removal of all carious dentin is absolutely essential to success. To allow any portion of it to remain and trust to the employment of germicides for its sterilization is running the risk of failure, for we can never be entirely sure of disinfection. Besides this, there is no good reason for allowing cari- ous dentin to remain. By carious dentin is meant the remains or debris of the action of REMOVING THE DECAY. 137 caries, — a product resulting from this disintegrating action upon both the organic and inorganic constituents of dentin. In nearly all cavi- ties we find tico varieties of altered tissue. That nearest the surface is a mass of thoroughly disorganized and usually decomposed matter filled with micro-organisms. Beneath this and lying next to the healthy den- tin there is a zone or layer from which the calcium salts have been re- moved by the acid solvent, but which still retains its original form and vitality. This layer of decalcified dentin may be allowed to remain, especially in the bottom of a cavity, as it serves to protect the subjacent tissue from thermal shock and will in the great majority of cases be again converted into normal dentin by the re-deposition of calcium salts. As a precautionary measure, however, it should be treated to an applica- tion of some germicide such as carbolic acid, mercury bichlorid, or oil of cinnamon, before the insertion of the filling. Occasionally caries will be found to be self-limited. In such cases, through some unexplained change of conditions, the progress of caries has been checked and the layer of decalcified dentin been restored to its previous normal condition. Where this has taken place the restored tissue is usually of a darker color than ordinary dentin, and on this account may be mistaken for carious dentin and removed. It is, however, easily distinguished from caries by its hardness, and should in no case be removed except from the sides of a cavity, and then only when its dark color showing through the walls would prevent the cavity, after being filled, from having that clear and clean appear- ance which it should possess. With some practitioners it is the custom to prepare a cavity dry, because in this way the operation is more rapid and usually less painful. In such case the rubber dam is applied first of all and the operations of opening, cleansing, and shaping the cavity are all performed without the presence of moisture. Repeated applications of warm air from a syringe, at intervals during the operation, desiccate the dentin and di- minish its power of sensation. Others, in order to avoid the unpleasant- ness to the patient of having the dam in position for so long a time, prepare the cavity roughly in the presence of moisture, then apjjly the dam, dry the tooth thoroughly, and finish the operation. Whichever plan is adopted it is absolutely necessary, in all cases, to finish the preparation with the dam on and the tooth dry, for it is only after a tooth has been deprived of its moisture that we are able to decide whether all the niceties of preparation have been successfully carried out. Certain marginal and structural defects that are not noticeable while the tooth is moist are plainly revealed after it has been dried. 138 PREPARATION OF CAVITIES. Shaping the Cavity. This is one of the most important of all operations associated with the stopping of a cavity, for according as it is properly or improperly performed will success or failure result. Too much stress cannot be laid upon its importance, nor too great care be exercised in its accom- plishment. Inasmuch as a filling is retained in place mcchanicaUy it follows that the cavity must be of such shape as to favor retention. To this end it should be larger within (at least at certain points) than at the orifice. An exception to this rule lies in such cavities as are of small diameter and of more than moderate depth. In cavities of this character, parallel walls will suffice, because lateral-surface contact is so great in proportion to the mass to be held in place that displacement could not occur. In larger cavities of moderate depth, however, the reverse is the case, and they will require the assistance of internal enlargement for the retention of the filling. To govern each of the conditions two rules may be formulated : 1. When the depth of the cavity is greater than the diameter of the orifice, parallel lateral walls will prove retentive. 2. When the diameter of the orifice is greater than the depth of the cavitv, the latter will have to be somewhat enlarged internally to retain the filling. Examples of the first class are found in the narrow but rather deep cavities Avhicli occur on the lingual surfaces of the upper incisors near the cervix ; in the pit cavities on the buccal surfaces of molars ; and in the small cavities found on either side of the enamel ridge on the occlusal surfaces of the lower first bicusi)ids. Examples of the second class are found in numberless places on any of the crown surfaces. In some cases cavities will be found of such form that when the decay has been removed they will have a naturally retentive shape, but in the great majority of cases more or less sound tissue will have to be removed in order to give them the required fi)rm. To give a cavity a retentive form it is not necessary that its interior be enlarged throughout its whole extent, but it must be larger at two or more points, and these points must be opposite one another, Frecpiently it will be easier to enlarge the cavity at all points, and to this no objection can be urged provided too much sound tissue be not removed or the pulp be not too nearly approached. Too great enlargement tends to weaken the cavity walls and therefore should be guarded against. In shaping the cavity internally instruments should be employed that will leave the surface free from angles, for the filling material can- SHAPING THE CAVITY. 139 not be perfectly adapted to them. As in the removal of decay, excava- tors for this purpose should have curved edges, and burs should be of a round or oval form. If grooves are required they should neither be made deep nor too near to the enamel, for fear of weakening the walls. At the cervical margins of cavities grooves and starting pits should be avoided when- ever possible, for they weaken this portion of the cavity which is sub- jected to the greatest strain in the introduction of the filling, both mechanically and by cutting off the nutrient supply to the cervical margin, which tends to alter the resistive character of that portion of the tooth structure by devitalizing it. For the same reasons deep grooves or undercuts should not be made near the incisal or occlusal surfaces, for the strain of mastication will be liable to result in fracture of the wall if it is thus unduly weakened. In the process of shaping the cavity internally the enamel margins will naturally be assuming their ]3roper form, but the final part of the preparation should consist in giving these frail portals of the cavity very careful and minute attention. The value and permanency of a filling will largely depend upon the strength of the enamel loalls and their proper preparation. The enamel cap of a tooth when intact is exceedingly strong and capable of resist- ing great strain, but when its continuity has been broken by caries and it is left unsupported by dentin it is very Aveak and brittle. This is readily understood when we remember that enamel is composed of an aggregation of enamel rods or prisms in close juxtaposition, slightly joined together by a cementing substance, with their greater diameters perpendicular to the plane of the surface of dentin upon which they Fig. 99. Showing enamel strufture. rest. When continuous, these rods mutually su])port one another and are thus capable of resisting great strain ; ])ut when a lesion has occurred they lose support on the adjoining side and hence are easily separated in the direction of their length. Fig. 99 (after Black ^) shows this ^ Dental Cosmos, vol. xxxiii. p. 441. 140 PREPARATION OF CAVITIES. condition perfectly. A detached section of enamel prisms is represented at (I, and at 6 is shown a portion about being separated by a chisel. This will explain why enamel unsupported by dentin should not be allowed to form the margin of a cavity, for it will probably either be fractured while the filling is being introduced or afterward in mastication. On all convex surfaces of a tooth the enamel rods radiate outwardly, and by forming the margins of a cavity on these lines it will have a slightly flaring or trumpet-shaped orifice, which will not only aflx)rd the greatest strength l)ut will admit of a better finish being given to the edges of the filling. In many cases it will be necessary to give the margins of a cavity more of an outward bevel than would be obtained by simply follow^ing the cleavage lines of the enamel rods. This can be secured by cutting away the outer ends of the enamel rods in an oblique direc- tion as shown at c in Fig. 99. Ko weakening of the border will result in such cases, inasmuch as the shorter rods will still rest upon the dentin. If, however, the rods were cut so as to leave only their outer ends in place, as shown at d, they Avould have no substantial support^ and would be liable to be crushed daring filling or afterward. All cavity margins should have the outward bevel to a greater or less extent in order to secure the best and most permanent results. In cavities upon (Jejjrcssed or concave s>(rf((cc,-< of teeth it would not Fig. 100. ^^^ ^*^ have the enamel margins formed on the lines B B of enamel cleavae-e, for this would make the margin /iJ^LjK of the orifice the most contracted portion and result ^Hjra in frail marginal edges. Fig. 100, representing a 1^|W cross section of a bicuspid tooth with a cavity in the ,. ' . . sulcus, will illustrate this point : A shows the cavity Cross section of a bicus- ' i •' pid showing treat- orifice prepared on the lines of enamel cleavage, ment of enamel mar- i xi i • xi j. i X" i gins of cavity in the ^^^^ ^ t"^ dressing aci'oss the outer edges ot enamel sulcus. required to give the necessary strength. It may therefore be laid down as a rule that to secure the best results the line of a cavity w(dlfrom itntldn oatward slioidd form ivith the surface of the tooth at this point an obtuse angle. Beside the proper shaping of a cavity margin it should also be made as smooth as possible. In accessible cavities u})t)n exposed surfaces of teeth the final marginal smoothing or finish can best be effected by the use of a l)ur shaped somewhat like a fissure bur, but having a rounded end and being simply file-cut upon its surface instead of being bladed. Such a one is shown in Fig. 101. Its sides being parallel, no rounding of the cavity margins can occur when it is used with the end inside of the cavity. Any other form of bur with a short head would unavoidably give to the cavity margin either a concave or a convex surface, both of which would be incorrect. CLASSIFICATION OF CAVITIES. 141 The buccal, lingual, and cervical margins of a compound approximal cavity should never be finished with a bur, even of the plug-finishing variety, but should be smoothed with suitable chisels, broad-faced excavators, or approximal trimmers, the latter being shown in Fig. 102. Fig. 101. Fig. 102. File-cut enamel finishing bur. Approximal trimmer. The practice of finishing cavity margins with sand-paper disks, Hindostan-stone points, or wooden points charged with emery powder is very objectionable, as they are almost certain to give to the margins a rounded edge which cannot be filled and finished without leaving a feather edge of the filling overlying the enamel, which will eventually be broken off or flared up, leaving an imperfect margin. Classification of Cavities.^ I. SiJviPLE Cavities on Exposed Surfaces. Bicuspids and Molars. Incisors and Cuspids. A. Occlusal. -D. Labial. JB. Buccal. U. Lingual. C. Lingual. F. Incisal. II. Simple Approximal Cavities. Incisors and Cuspids. Bicuspids and Molars. G. Mesial and distal. H. Mesial and distal. III. Compound Cavities. Incisors and Cuspids. Bicuspids and Molars. I. Mesio-labial. P. Mesio-occlusal. J. Disto-labial. Q. Disto-occlusal. K. Mesio-lingual. R. Occluso-buccal. L. Disto-lingual. 8. Occluso-lingual. M. Mesio-incisal. T. Mesio-disto-occlusal. N. Disto-incisal. 0. Mesio-disto-incisal. ^ Following the suggestion of Dr. Black, in the above list the word lingual is used -for the same surfaces in both the upper and lower teeth, doing away with the word 142 PEErARATIOX OF CAVITIES. In the foregoing classification the cavities have been arranged pro- gressively from the simplest (A) to the most complicated (T). I. Simple Cavities on Exposed Surfaces. BICUSPIDS AND MOLARS. Class A. — Cavities upon the occlusal surface are very accessible and in full view, enabling the operator to see every part of the cavity and affording him plenty of room in which to operate. Naturallv those nearest the front, as in the bicuspids, present the advantage of greater accessibility, but none of them are difficult to prepare and fill except under unusual conditions. Usually the first part of a bicuspid crown to become affected by caries is the fissure between the cusps. Sometimes it presents merely as a black line into which only the point of an explorer will penetrate ; at a later stage the cavity is more fully defined by the greater pro- gress of caries and the crumbling of the walls of its orifice. In the first instance the cavity is most readily and comfortably opened by means of the tapering fissure bur shown in Fig. 94. After passing it into one of the terminal pits of the cavity it may be drawn along toward the other, opening the fissure quite freely. Once open, the decay may be removed and the cavity shaped by a suital>ly sized round bur (Fig. 93). As the decay has usually progressed farther in the region of the terminations of the cavity than in the space between them, the cavity when fully formed will be oblong in shape and contracted in the centre. In Fig. 103, A shows this form, while B represents the same surface before being operated upon. In preparing the cavity no more sound tooth-structure should be sacrificed than is absolutely necessary, l)Ut every portion of decay should be thoroughly removed and })articular attention be given to opening up the minor fissure terminations as shown at A, A, B, B (Fig. 104). AVhen completed, the cavity should be very slightly larger within than without, the margins should present no angles, but only a series of curves in outline, and the marginal edges should be slightly bevelled outwardly. Bicuspid cavities of this character vary in size according to the extent of decay, but the essential features in each case are very similar. The palatal. In the forming of compound terms, where the metiial or diMal surfaces are inchided. these terms precede tlie others. Where they are not included and the word occlusal is used, it is given first place. Fig. 103. Cavity in sulcus of a bicuspid. B B The fissure terminals. SIMPLE CAVITIES ON EXPOSED SURFACES. 143 lower first bicuspid diiFers normally from all others of its kind in having no sulcus and consequently no fissure between the cusps. In- stead of the two cusps being separated by a sulcus they are united by a ridge of enamel. (See Chap. I., p. 35.) The only points, therefore, that invite decay upon the occlusal surface of this tooth are the two pits that are -found, one on each side of the ridge. These are to be filled separately. They probably represent the very simplest form of simple cavities to be found anywhere in teeth. The occlusal surface of an upper first or second molar presents two points liable to decay. One is a pit formed by the junction of two small fissures near the mesial margin, and the other is a fissure which runs between the disto-buccal, disto-lingual, and mesio-lingual cusps. Both are represented in Fig. 105. When limited in extent they should be opened in the same manner as a bicuspid fissure cavity, but when larger they may be opened by means of a chisel followed by a suitable bur. In these, as in all cavities in sulci, the fissures must be followed and opened up to their extremest limits in order to ensure success, while the margins and marginal edges must be so formed as to be strong, smooth, and bevelled. The general form of these cavities when prepared is shown in Fig, 106. It will frequently be found that these two occlusal cavities Fro, 105. Fig. 106, Fig. 107. Fig. 108. Molar Assure cavities. Molar fissure cavities prepared for filling. are joined underneath, while near the surface they are separated by a ridge of enamel and dentin. In such cases the ridge should be cut away and the two cavities converted into a single larger one as illus- trated in Fig. 107. If the ridge were allowed to remain it would almost certainly be fractured either in the operation of filling or subsequently by the force of mastication. The upper third molar differs from those anterior to it in having but three cusps and consequently but one central pit with radiating fissures, A cavity occurring here when properly prepared will pre- sent a triangular outline with rounded angles, as in Fig, 108, The terminals of fissures should always be finally finished with a round bur to prevent any possible angles and opportunity for leakage at those points. The lower first molar, as well as the third, having five cusps with intervening sulci, a cavity upon this surface will be pentagonal in out- line, as represented in Fig. 109. 144 PREPARATIOX OF CAVITIES. Extreme care should be exercised in preparing cavities of this character to ensure that the fissures running between the buccal cusps are fully opened and cleared of every particle of decay and discolora- tion. Too often this is overlooked and caries supervenes. The lower second molar with its four cusps has tAvo sulci inter- secting each other at a right angle. Decay usually begins at the inter- section and extends along the radiating arms of the fissures. If the cavity Avere prepared by cutting out the fissures only it would yield a crucial-shaped cavity with four sharp or nearly sharp angles at the intersection as shown in Fig. 110. Owing to these angles of dentin Fig. 109. Fig. 110, Lower first molar with stel- late cavity. Prepared. Lower second molar with crucial cavity. Not pro- perly prepared. Prepared cavity in lower second molar. and enamel the perfect filling of the cavity would be exceedingly difficult. Tlie case may be simplified and better results in every Avay obtained by rounding these angles and giving the cavity a form like the one shown in Fig. 111. Class B. — Buccal cavities are seldom met with in the bicuspids except at the cervix. In this location they possess the same features as the similar class of cavities occurring; on the labial surfaces of the incisors. Their treatment will be described under class D. The upper molars also are seldom found decayed on the buccal sur- face except at the cervical l)order. Cavities occurring at this point are usually narrow and long, following the outline of the gum. They can best be prepared with an engine bur of suitable form, and if occurring on the second and third molars a rioht-anole attachment mav have to be employed to reach tlicm conveniently. Decay at this point is often of the white variety, and as it so nearly resemljles the natural color of the tooth extreme care will have to be exercised to include all of the decalcified portion within the limits of the cavity. A retentive form is most conveniently given to these cavities by slightly undercut- ting them in the direction of their length. In the third molars it is sometimes advisable to make an undercut or starting-pit at the distal end for the beginning of the tilling. Sometimes a small cavity will be fi)und at about the centre of the buccal surface of the upper molars, but far more frequently a cavity of greater extent will be fi)un(l upon the same surface of the lower second molar. It originates in a pit at the termination of the fissure SIMPLE CAVITIES ON EXPOSED SURFACES. 145 running over from the occlusal to the buccal surface between the two buccal cusps. Oftentimes the cavity is so large as to include the greater portion of this surface of the tooth. Its usual form and appearance are shown in Fig. 112. Not infrequently this cavity is compounded with one on the occlusal surface. In opening and preparing it a slightly undercut form is readily given to it. Class C — Decay rarely occurs upon the lingual sur- faces of molars on account of their smoothness and con- vexity, and because they are more or less constantly rubbed ^^^cai cavity by the tongue in speech and mastication. The evenness of in lower sec- this surface is, however, broken in the upper first and sec- ond molars by a fissure extending over from the occlusal surface and passing between the two lingual cusps. (See Chap. I., p. 39.) This fis- sure is deeper and more pronounced in the first molar, but in each tooth it is generally the seat of caries early or later in life. In the majority of cases this fissure is decayed throughout its entire length, forming a compound cavity, but occasionally only the pit at its termination on the lingual surface is aifected. Another point on the lingual surface liable to decay is on or near the mesio-lingual angle of the upper first molar, about midway between the cervical and occlusal margins. At this place is often found a supple- mental cusp, diminutive in size, and where it joins the main surface of the tooth a small fissure exists which invites decay. This additional cusp, when it does exist, is found only upon the ^^^' -'^'^• first molar. It is shown at A in Fig. 113. (See Chap. I., p. 39.) Neither of these cavities presents any diffi- culties in preparation except such as occur from their slight difficulty of access. Occasionally, though very rarely, the lingual surface of any of the molars may present a cavity of decay close to the gingival line and partly beneath it. Such cavities are doubtless caused by the retention of food debris beneath the free margin of the gum, and owing to their position they are difficult to treat. They should be opened and packed over-full with cotton and varnish or gutta-percha for a day or two, to press the gum away, after which they may be prepared and filled in the usual manner. INCISOES AND CUSPIDS. Class D. — Cavities upon the labial surfaces of incisors and cuspids are usually found along the gingival margin, and are the result of the direct action of acids probably formed at this point. In the beginning, and when small, they are entirely exposed, but wdien of greater extent 10 146 PREPARATION OF CAVITIES. they frequently extend beneath the free margin of the gum. They are nearly ahvays elliptical in outline and may consist of simple decalcified enamel still retaining the usual surface form, or they may possess the common characteristics of cayities in general. The opening and preparation of this class of cayities are not attended with any marked difficulties except that when they extend beneath the gum care will haye to be exercised not to wound this tissue, as the consequent bleeding would obstruct the yiew and interfere with the progress of the work. This may be preyented by pressing and holding the gum away with a suitable instrument held in the left hand while the cavity is being prepared. Particular attention should he paid to the care- ful preparation of the cervical margin of the cavity and to its terminal points. The former should be made smooth and even, and the latter should be extended far enough to include any enamel that shows the least sign of acid alteration. Slight grooves or enlargements at the base of the cavity along its upper and lower margins will give it a suf- ficiently retentive form. A second locality on the labial surface where decay is frequently found is anywhere between the central portion and the incisal edge, in pits and depressions that indicate imperfect development of the enamel. These pits or grooves extend in a nearly straight line parallel to the incisal edge, and are frequently the seat of decay. When quite shallow they may ])e obliterated by grinding the surface with a small corundum wheel and polishing, converting the surface at this point into a distinct concavity. When the pits are deeper and isolated they may be filled separately, the result being a lesser degree of conspicuousness ; but when they are connected by a groove, as they usually are. Pitted iucisor. tlicv will havc to be Converted into a single cavity and filled. A common type of this defect is shown in Fig. 114. When these pits occur upon the incisal edge or in close proximity to it the choice lies between an unsightly gold filling, a porcelain tip, or their removal by grinding and the resultant shortening of the crown. Class E. — There is usually but one point upon the lingual surface of incisors and cuspids that is liable to decay. It is in the pit at the junction of the basilar ridge or cingulum with the adjacent tooth surface. The incipiency of caries at this point presents only as a mi- nute cavity, the o})ening and shaping of which is readily accomplished with a round bur. Although the orifices of these cavities may be small, the dark spot that marks their direction is often continued quite a distance toward the pulp-chamber. This black point should in all cases be followed to its termination and obliterated. It will never be found to reach the pulp or to approach dangerously near it. As the SIMPLE APPROXIMAL CAVITIES. 147 depth of these cavities is greater than the diameter of their orifices, no special retentive shape need be given them. The orifice should always be bevelled and enlarged, if necessarv, to include any neighboring fissures. When these cavities are of greater extent they are prepared and filled like others of similar size and form. Class F. — Cavities upon and confined to the incisal edge or surface of incisors and cuspids are easily prepared on account of their accessi- bility. This particular surface should, and generally does, remain free from decay on account of the attrition to which it is constantly sub- jected ; but when defects in the enamel exist, caries sometimes occurs in connection with them. This surface often needs covering with gold to check abrasion in cases where, after middle life, the crowns (especially those of the upper teeth) have been shortened by excessive wear. Under these conditions the surface has to be so prepared and shaped as to retain the gold that is to cover and protect it just as though caries had originally injured the part. In forming the cavity in the exposed dentin it is only necessary to cut deeply enough to afford a lodg- ment for the filling, but the orifice must be so enlarged and cross-section of excessively bevelled as to reach to the marginal edge of cavity on in- enamel all around. This is done to protect the enamel from chipping or fracture in mastication. To afford the greatest security to the filling the cavity should be undercut throughout its whole extent. When thus prepared, the cavity in cross section will resemble a double dove-tail as shown in Fig. 115. II. Simple Approximal Cavities. INCISOES AND CUSPIDS. Class G. — Cavities upon the mesial and distal surfaces of the anterior teeth present only the difficulty arising from inaccessibility. To reach and operate upon these cavities, the teeth, if in normal contact, will usually have to be pressed apart either by gradual wedging or by immediate separation with a " separator." Even after this has been accomplished the cavity cannot be operated upon in a direct way as are cavities upon exposed surfaces, but will have to be approached from either the labial or lingual aspect of the crown. To do this, if the cavity be small, will generally necessitate an additional enlargement of the cavity toward the surface from which it is to be approached. As the lesser of two evils the enlargement is usually made toward the lingual surface, for in this way the exposure of gold Avhen the filling is 148 PREPARATION OF CAVITIES. completed will not be noticeable. When the cavity is of larger size and the enamel wall on the labial surface has been weakened by caries it will have to be removed, and access will thus unavoidably be atibrded from that side. AVhenever possible, however, undue enlargement of the cavity and consequent exposure of gold should be avoided. In ordinary cavities upon the appro.vimal surface the frail walls bordering the orifice should be broken awav with riG. 116. a small chisel, and after the decay has been removed by means of burs or excavators and the proper form given to the cavity, the margins should be carefully smoothed and bevelled with small plug-finishing burs or with the side-cutting edge of the small chisel shown in Fig. 97 and here reproduced (Fig. 116). Anchorage is obtained in these cavities by slightly deepening the cavity at its cervical termination and making a shallow undercut in the dentin near the I I incisal border. Retaining grooves should never be Delicate three-sided made in the labial or lingual walls of the cavities, chisel, useful for ^j , jj^| ge^.i^,,^! weaken them. In ainnv.xi- opening cavities on - - i l approximai sur- mal cavitics of large size where they extend from near the incisal edge to or beyond the free margins of the gum, the difficulties of producing a perfectly formed cavity are greatly increased. While affording greater ease of approach on account of their size, the cervical border of this class of cavities is apt to be less perfectly prepared owing to its obscure location. When the cervical border extends beneath the free margin of the gum the latter should be pressed and held away duriug excavating, so that the cervical wall may be plainly seen and operated upon throughout its whole extent. Cutting of the wall should be sufficiently extended rootward to in- clude any defects or checks in the enamel bordering it, and should be made entirely smooth and free from angles, for it is the most vulneral)le border of the cavity after the filling has been completed. Should the cavity extend to near the enamel termination at the cervix, it will be best to still further extend it so as to pass beyond this margin ; for if a small portion of enamel be left there it will be liable to be broken away in the process of filling and thus seriously impair the junction of the filling with the border. So, also, if the cavity on account of its size should approach very near to the incisal edge, it is best to remove this frail corner and eon- vert the cavity into a compound one. Where such a \veak corner is allowed to remain it is very fre(|uently broken away in subsequent mas- tication. This result is shown in Fi<>:. 117. An accident like this is SIMPLE APPROXniAL CAVITIES. 149 the more likely to occur in thin, flat teeth where the plates of enamel meeting at the incisal edge have little or no dentin between them. Where doubt exists as to whether the corner should be ^ ,,_ removed or allowed to remain, it is well, after the cavity has been prepared, to test the strength of the corner by strong pres- sure upon it in the direction of the long axis of the tooth with a piece of orange-wood. If it resists this strain it will prob- ably resist the force of mastication, and if it break away under the test it will demonstrate that it would have been unwise to allow it to remain. If the corner be left as a border and support for the filling it should not be weakened by a deep retaining groove. Such groove or anchorage should be shallow, and as far removed from the incisal border as the conditions will permit. In many cases, where the incisal wall would be seriously weakened by any attempt to use it as an anchorage or support for the filling, and where it seems undesirable to remove it, an ex- cellent anchorage for the lower border of the filling may be obtained by cutting an extension upon the lingual surface in the form of an arm, as show^n in Fig. 118.^ Such extension, if made but little deeper than the enamel, will not materially weaken the tooth and will secure the filling perfectly. Lingual ex- Its position should be near the incisal edge, but not so tension an- , • , 1 chorage. close to it as to weaken the part. In the anterior teeth the relative difficulties between mesial and distal Cavities are insignificant. BICUSPIDS AND MOLAES. Class H. — The preparation of small cavities on the medal and distal surfaces of the bicuspids and molars, though simple in character, is usually most difficult of thorough performance. This is due entirely to their inaccessibility when the teeth are closely approximated. How to approach these cavities is often a matter of no small concern to the student or young practitioner, and the preparation and filling of them is generally more difficult than that of larger and more complicated cavities in exposed situations. To lessen the difficulty of approach it is important, whenever practicable, to create by wedging beforehand as great a separation as possible between the teeth. The greater the space gained the less the difficulty of approach. When conditions will not warrant cutting down to them from the occlusal surface, and thus converting them into compound cavities, but two ways of approach are left open : one is from the direction of ^Dental Review, vol. ix. pp. 812 and 819. 150 PREPAEATIOX OF CAVITIES. the occlusal surface, and the other from the buccal aspect. Usually the former is chosen, as it involves less sacrifice of tooth structure, although by it the difiiculties are increased owing to the limited space iu which we are obliged to operate. These cavities can usually be best opened and mainly prepared with a round bur. After the decay has been removed and the walls defined and prepared, the cavity may be made retentive iu Ibrm by slight under- cutting throughout its entire circumference, or it may be enlarged at two opposite points only. The cervical wall can be inwardly deepened by an obtuse-angle excavator as illustrated iu Fig. 119, and the lower or occlusal wall be slightly undercut by an acute-angle excavator like Fig. 120. Fig. 119. Fig. 120. Obtuse-angle hoes. Acute-angle hoes. The sharp angles on the cutting edges of these excavators should be rounded before being used, so as to avoid the formation of angles in the cavity. As the enamel rods on this surface radiate outwardly at such an angle as to give the proper bevel to the orifice of the cavity, a careful following of their lines in the preparation of the cavity margins will be all that is necessary to give them the desired form and strength. Occasionally these cavities, instead of being round or nearly so, have a decided oval or oljlong form, their greater diameter being in a bucco- lingual direction, in which event the cavity may generally be best ap- proached, for preparation and filling, from the buccal aspect. When this seems desirable, the cavity should be extended so as to open at the approximo-buccal angle. A round bur is best suited for this purpose, and when the extension has thus been made the cervical and occlusal walls of the cavity may be slightly grooved with a hoe excavator and the inner or lingual wall be made abrupt and also slightly undercut. In all cases where sufficient space cannot be gained to operate sati.s- factorily from the direction of the occlu.|). SI 2 and S19. * I. C. St. John, L). 1). S., Dental t'- 137. stances the flow is naturally excessive, and in all cases it is stimulated by the operative procedures. An excessive flow of saliva is uncomfortable to the patient, by its accumulation it impedes the operation, and it interferes with the view of parts by refracting ^ the rays of light. During the preparation of accessible cavities, par- ticularly those of the upper front teeth and the occlusal surfaces, the accumulation may be carried off by the use of a SALIVA EJECTOE, a simple form of which is shown in Fig. 136, which form, or some modification of it, is used where a connection can be made with the water supply, and ordinarily it is used in association with the fountain cuspidors. An- other form, which is connected with a small reservoir of water, is shown in Fig. 137. Either of these forms has a further use for drawing off the saliva in con- nection with the employment of the rubber dam to lessen the dis- comfort of the patient. Use op Rubber Dam. During the preparation of cavi- ties on the approximal surfaces, ■where it is essential to have unrestricted view and the exclusion of blood, 157 158 EXCLUSIOy OF MOISTURE. the presence of "which is inseparable from thorough preparation of the cervical margins, it is necessary to make use of the eubber dam. When used for this purpose the material generally becomes impaired bv the action of the instruments in their free use at the cervix ; but the economy of time and the essentials of thorough performance of this class of operations warrant the application during this portion of the treatment. AVhen the case is ready for the filling process a new piece of the dam ^h(>uld be prepared, and adjusted with great care to prevent the ingress of the least moisture. "Without this appliance the greatest skill is pow- erless to secure sound results in large, difficult, or complicated cases. The introduction of this invention has made it possible to execute with gold, operations which previously were impossible ; not the least advantage resulting from its use is that the operator has free use of the left hand to assist the right. Quality of the Rubber. — The quality of the rubber greatly modi- fies the facility of its application. It should be of medium thickness and of light color, as it then absorbs less light. It should be freely extensible and so elastic that when the thumb is forcibly pressed into it it returns to its normal form on the removal of the force. If it re- sponds to that test it will not tear if fairly applied. The size and form of the piece should be such as to avoid encum- bering the face of the patient and to permit the lateral extension to be folded out of the way in such manner as to prevent obstruction of the view. The form generally best suited is a triangle, which form alsa permits of its most economical use. For the front teeth the piece should be moderately small ; for the bicuspids and molars the size should be ample and is best adapted when cut from strips about seven and a half inches in width. The selected piece should have holes cut in it of such size as ta correspond with the dimensions of the teeth over which it is to pass. AVhen more than one hole is required the holes should be at such dis- tances apart as will present a sufficient amount of material to allow for the take-up in the application, so that the strait which passes between the teeth shall be sufficient to allow the edge to ])e carried upward ta form a valve at the cervices of both teeth and not be under such strain as to interfere with the valvular action of the edges of the rubber. At the same time there should be no excess to hamper the view or inter- fere with the placement of the filling material. Attention to the valvular arrangement of the dam at the cervix will avoid subsequent difficulty and will prevent in many instances the infliction of pain in using ligatures except upon the tooth under treat- ment and the adjacent one. The appearance of this valve is shown in USE OF RUBBER DAM. 159 FiCx. 139. Fig. 138. h c d Diagrammatic drawing : form of valve. section by Fig. 138, a, b, c, d. The holes in the rubber may be formed with a punch of suit- able size, which should be forced upon the end of a close-grained piece of hard wood. They may be made with a little practice by drawing the rubber over a round-ended instrument with some force and pricking the rubber at a suitable point with a sharp knife, when a round section escapes. The diiference in size of the holes is deter- mined by the distance from the end of the instrument at which the puncture is made. The deter- mination, however, of size and distance is not so easily made in this manner. The best ap- pliance for the purpose is the Ainsworth punch (see Fig. 139), with which complete control of size and distance may be easily eiFected. The arrang-ement of the holes in the triangular piece should differ for each section of the mouth. Fig. 140 shows a piece for the central incisoj^s. sent inches. Fig. 141 shows the arrangement of holes for the upjm- bicusjMcls The Ainsworth punch. The figures repre- 160 EXCLUSION OF MOISTURE. and molars. It will be observed the line of holes is not parallel with the upper edge. For central incisors. Fig. 141 Fig. 142. For upper bicuspids and molars. For lower bicuspids and molars. Fig. 143. For lower front teetli. Fig. 142 show.-^ the arrangement for the lower bicuspids and molars. Here, too, the line of holes is not parallel with the edge, to allow for the difference in distance from the commissure of the lips to the ante- rior and posterior holes. Fig. 143 shows the arrangement when the incisors and cuspids are included. Here the line of the apertures is curved. By conforming to these arrangements of the openings in the riil)ber, and V)y extend- ing tlie line in conformity with it, as well as by increasing the size of the piece, any num- ber of holes may be made to include any portion or all of the teeth of one quarter of the denture when that may be required. The number of apertures in the rubber should be such as to give easy access to the operation and to permit the free entrance of light. For the anterior teeth five to six holes are necessary, and for the pos- terior teeth from four to six as may be needed to secure the above stated objects. In general, at least two teeth anterior to the one operated upon, and Avlien admissible the one posterior, should l)e included. The Placement of the Dam. — When the teeth are not in firm con- tact or where their attachments are flexible the adjustment of the dam is simple. But when the teeth are rigid certain ])reliminary conditions should be secured. It has been pointed out in .'^peaking of the })repara- tion of the teeth for a series of operations that they sliould be well cleaned of any deposits whicli may be upon them and be polished on their a])proximal surfaces. This makes easier the insertion and the aj)plication of the rubl)er. Generally where the case under treatment is an approximal surface the necessary preparatory sejiaration makes easy the immediate open- ing of any interstices near the (tperation. In cases of extreme fixa- tion of the teeth a piece of rul)ber dam placed for a day or so in a USE OF RUBBER DAM. 161 couple of the neighboring spaces makes it easy to enter the margin of the apertures. The passage of a silver tape with a little benne oil or cosmoline on it answers as an equivalent means. In the front teeth a thin wedge inserted just above a tight point permits an easy entrance. The preliminary silking of the adjoining spaces, particularly if the silk be coated with cosmoline or its equivalent, also facilitates the passage of the rubber, and for this purpose soaping the under surface of the rubber adjacent to the holes is recommended. At first the novice finds difficulty in making application of the dam, but practice cultivates facility. In general it is better to commence with the anterior hole and proceed posteriorly until all the intended teeth are included. Thus for the left lower teeth the rubber is taken with the index fingers applied to the upper surface, the other fingers to the under surface, and is grasped near the hole for the front bicuspid ; the hole is extended ; the edge of the rubber is inserted in the interstice and is carried down to the gum. It is then drawn over the tooth and passed into the next interstice in the same manner. This method is pursued with each tooth until all the intended ones are included. The passage of the rubber is facilitated by keeping it downward by the in- sertion of floss silk which is held taut, and with a firm and gently sliding movement the rubber is conveyed toward the cervix. When the most distant tooth is the third molar it is generally best, when the cavity is on either side of the last interstice, to pass the jaws of a dam clamp through the posterior hole ; the clamp is then made to grasp the tooth, the dam is conveyed to the gum by silking, and the adjustment is then carried forward from tooth to tooth. The same pro- cedure is sometimes applicable with short third molars in the upper denture, or in case any of the posterior teeth are so shaped as not to retain the rubber. "When the rubber is adjusted over the teeth the purpose of the dam is eiFected by directing the edge of the dam under the free margin of the gum. This is done by passing a silk thread around the tooth, and crossing the ends, when by a drawing movement of the thread it travels down the inclined surface of the cervix, carrying the dam with it, thus making a more secure formation of the valve. This method avoids the needless paining of the patient caused by pushing the threads against the gum with instruments. Whenever necessary for securement the ligature may be tied. This should be done on the teeth on both sides of an approximal cavity. It is necessary here to place the cervical margin of the cavity in full view and to make certain the exclusion of moisture, which otherwise might pass the valve by capillary attraction. The ligature should usually be passed but once around the tooth and 11 162 EXCLUSION OF MOISTURE. then be tied with a surgeon's knot, the place of the knot being on the outside. When there is much strain the thread may be passed twice around the tooth, but this should be avoided as being more painful and as increasing the bulk of the ligature. To prevent the rubber from displacement by the movement of the cheeks on the posterior teeth when they are long, if after drying the surface a little sandarac or damar varnish is applied at the last inter- stice, the rubber becomes fixed. In cavities extending above the cervix where a ligature cannot be placed above the cervical border of the cavity, other means have to be adopted to obstruct the entrance of fluids. Here the strait of rubber between the holes should be much wider than usual ; the abundant fold may then be forced beyond this margin with a matrix, when, by drying the parts and by the deft introduction of alcohol varnish and suitable wedges, dryness of the parts is attained. In the most extreme cases of this nature the part beneath the normal gum line may be filled with a permanent plastic substance, as described in the section on Lining Cavities (see Chapter YIII, p. 175). The Securement of the Dam from Displacement, — AMien the teeth are short from incomplete development or when their form is tapering from the gum toward the occlusal aspect there is always some tendencv of the rul)ber to escape, and the contraction of the commis- sure of the lips always tends to the displacement of the dam at the posterior teeth, the latter movement often being sufficient to overcome the friction of the ligatures. When these difficulties arise a clamp is required. The Clamp. — This is an instrument of much value not only as a means of securement of the rubber, but as an adjunct to prevent the rubber from obstructing the view. Clamps are more especially needed to detain the rubber on the molars and are rarely required for the bicus- pids or the anterior teeth, since, if the foregoing directions are followed, the necessity for their use will but seldom be jiresented. Tlie FoniiH of Clumps. — For the molars various sizes and shapes of Fig. 144. Fig. 145. Dr. Southwick's clainps. Dr. Huey's clamps. the " Southwick " and of the " Huey wisdom-tooth clamp " are sufficient for general use. In addition to these " Palmer's set of eight," after USE OF RUBBER DAM. 163 the sharp points of the jaws are rounded, will furnish the requisite variety. Fig. 146. Dr. Delos Palmer's set of eight clamps. The Application of the Clamp. — The selected clamp is extended by the clamp forceps to enable it to pass over the molar. It is con- veyed to the middle portion of the tooth, when the inner beak should be brought against the tooth at the gum margin, when with this point as a fulcrum the outer beak is carried to the cervix on the buccal surface. Much pain may be avoided in the employment of this appliance by deft and careful placement. Injury of the gum and needless pain has frequently been inflicted by careless use of force in the application of this appliance. Much of this may be avoided by the previous ligation of the tooth, which will prevent the tendency of the clamp to descend beneath the gum when the necks of the teeth are much inclined inward. When it is necessary to force the clamp against the soft tissues the previous application of a solution of cocain will obtund the tissue and render the application tolerable. The Arrangement of the Dam on the Face. — This concerns the con- venience of the operator and the comfort of the patient. To give easy access and permit the entrance of light, the rubber is drawn aside at each upper corner by dam-holders. The simpler forms of these are sufficient and are more Fig. 147. Novel rubber-dam holder. 164 EXCLUSION OF MOISTURE. convenient than the more complicated ones ^vhen triangular of rubber are employed. In addition a supporter shown at Fig. 149 passes over the head and engages at each end with the holder. The comfort of the patient is se- cured by including a napkin along with the rubber in Fig. 148. Design of Dr. Cogswell. A suiiporter. the clasps of the holder. The excess of the rul)ber at each side should be taken up in a fold and secured to the napkin by dressing pins. The suspended part of the rubber is kept taut by pendent weights. The ap])lication and arrangement of the dam becomes by practice a very simple matter, and should not be the occasion of discomfort or pain to the ])atient. The Use of Napkins. — There are many instances of simple cases in accessible positions not of approximal surfaces, when the general flow of saliva can be kept under control by the saliva ejector, when it is not necessary to use a rubber dam. Also for children when the teeth are too short to permit the correct application of the dam it is necessary to find other means to control the moisture. Here the reliance is upon napkins, and with them much skill may be displayed by deft operators. For this purpose the napkin should not be over eight inches square. The manner of folding is to carry two corners to the hypothcnuse, then fold each side again to the same line, and continue turning these two halves toward each other ; l)y this means the folds are retained from displacement. To a]iply a na])kin to the upper rir/Jif ^ide the point is taken l:)etween the riglit index finger and the tiiuml), the lu'oad end being held at the same time by the left hand. The lip near the right commissure is everted, the point is inserted here, and by the taut action of the left hand the napkin is next laid between the gum and the lij). It is next carried backward until it reaches the duct of Steno, when the left index finger is ap|)lied to maintain the c(mipression at this latter jioint. The free end of the napkin lies upon the lower lip. For the left side the action is the same by the reversal of the hands. USE OF RUBBER DAM. 165 For the loicer teeth tlie ajaplication diifers by commencing for each side at the upper cuspid of that side. When the duct of Steno is reached a longitudinal fold is made to effect the compression of the orifice of the duct, then the napkin is laid between the cheek and the lower teeth and kept in position by the left index finger, a mirror, or a cheek-holder. An important preliminary to the application of a napkin to these positions is that the ejector be first placed in action and that the surfaces of the gum and cheek be wiped to dryness, to cause the napkin to cling to the surface. If the surfaces are covered with mucus and at the same time are wetted with saliva the napkin easily becomes displaced. For the inner surface of the lower teeth a considerable fold of hihu- lom paper laid beneath the tongue materially prevents access of saliva here, and also, by preventing the contact of the tongue with the teeth, lessens the opportunity for the approach of moisture by capillary attrac- tion between the tongue and the teeth under treatment. In instances where the form of the parts permits, the fold of paper or of linen may be retained in place by a dam clamp upon any adjacent posterior tooth. For the medication of cavities where it is important to confine the remedy to the tooth ; in short operations such as temporary shapings, and particularly for the simpler Fig. 150. Fig. 151. The Denham shield. Shield in use. cases of children, the Denham coifer-dam shields shown in Figs. 150, 151 are of much advantage, more particularly for the lower teeth. AVith these the ejector forms a valuable aid. XAUSEA. The contact of rubber dam with the tongue and the contiguous parts, the presence of napkins, and the touch of the fingers to the oral surfaces frequently excites nausea. With some persons this kind of distress is extreme and produces a species of faintness and nervousness. This condition may generally be relieved by the use of aqua camphora, a few drachms being used as a gargle to the mouth and the throat. When 166 EXCLUSIOX OF MOISTURE. indications of fnintness appear a drachm may be swallowed with imme- diate benefit. In case excessive nausea is occasioned by the contact of the appli- ances with the tongue or palate, these surfaces may be painted with tincture of camphor. Camphor appears to relieve in these instances bv its antispasmodic power, and it is stated to have also a specific action upon the eighth pair of nerves. A condition somewhat simulating approaching syncope sometimes appears in connection with the use of the rubber dam, due to impeded respiration which is caused not so much by the obstruction of the mouth as by the unpleasant sensations occasioned ])y the application and pres- ence of the dam. This may at once be overcome by requesting the patient to breathe deeply through the nose. Nervousness coming on during any of the operations upon the teeth may as easilv and in the same manner be avoided. It will be observed that in neither of these conditions are the first signs of approaching syncope apparent, viz., sighing respiration, pallor, and clammy perspi- ration of the face. CHAPTEE VIII. THE SELECTION OF FILLING MATEEIALS WITH REFER- ENCE TO CHARACTER OF TOOTH STRUCTURE, VARIOUS ORAL CONDITIONS AND LOCATION, DEPTH OF CAVITY AND PROXIMITY OF THE PULP— CAVITY LINING, WITH ITS PURPOSES. By Louis Jack, D. D. S. The general object in view in the filling of a prepared cavity is to secure the future preservation of the tooth at that part from the recur- rence of caries. This involves a consideration of the character of the material to be used, in relation to its adaptability to the conditions of age, the quality of the teeth, and the oral conditions which for the time are an expression of the general state of the organism. The habits of the patient as to general care of the teeth also have some bearing upon the probability of permanence of the reparative operation. A material adapted to preserve the teeth when they are of resistant quality and when the general health is sound and the care good, may be out of place when the opposite conditions exist. Methods of procedure have some bearing upon the result, and the influence of these has also to be kept in view. The general characteristics of the material to be used as a pre- servative of tooth structure are of importance in the following order : Resistance to chemical action ; Capability of adaptation to the surface of the cavity ; Sufficient hardness to withstand the force of mastication and the con- sequent attrition. Form and smoothness are also important as bearing upon the ques- tion of cleanliness, which more than any other indirect influence has the greatest bearing upon the preservation of the margins from sub- sequent softening, as will further appear. The Materials. The various accepted materials in use are : gold, tin, amalgams, the basic oxid cements, gutta-percha. The first three named may be designated as permanent in their cha- 167 168 FILLTSG MATERIALS. racter, and the others as of a temporary nature, which, after fulfilling important uses in this way, are often prei)aratory to later and permanent treatment. Gold. — The properties of gold which adai)t it for the restoration of carious teeth are its plialiility and softness, Avhich permit its adaptation to the form of the cavity ; its tenacity, which gives facility of introduc- tion and consolidation ; and its agreeableness of color, which, when the surface is solid, smooth, and unburnished, approaches more nearly the shade of the teeth than any other metal. Xotwithstanding these appropriate qualities the packing of gold requires the employment of considerable force to overcome various resistances to its adaptation and solid condensation. To effect the requisite degree of density percussive force generally becomes necessary. The effect of percussive force, if employed throughout, is liable to be expended on the margin toward which it is directed, and while this may not inflict any injury upon the borders of cavities when the dentin and enamel are dense, it often proves injurious to teeth when the anatomical elements of the structure are not homogeneous and resistant. While it may be stated with the strongest assurance that gold pos- sesses the highest preservative qualities and promises greater durabil- ity and more satisfactory results than any other material, conditions are often presented when to persist in its use would lead to unsatis- factory results. Thus in the approximal cavities of the teeth of children, when the calcifying jirocess has not become complete and when by the use of the required fierce some impairment of the incomplete tissues is almost certain to ensue. The same maladaptability occurs later in life when senile conditions have set in, when the teeth not only have lost their density from the peculiar molecular changes which take place in the dentin and enamel, but when usually also their resistance to chemical influences is greatly impaired. These conditions, coupled with the usual inability to properly care for the teeth, render the use of gold very questional)le. Similar states of the dental tissues take place in middle life in both sexes, but more particularly in women during the pregnant state, when the teeth lose their resistant power, which may later be restored. While this condition lasts, materials requiring less force should be selected until restoration of resistance has occurred. The mode of effecting percussion should be taken into account in estimating the influences which bear against the use of gold. When percussion is effected by the electro-magnetic instruments with proper precautions with respect to the placement of the first portions of gold, there is less danger of marginal injury than when percussion is made with the hand or the automatic mallet. GOLD—TIN. 169 Finally, the fact must also be recognized that in cases in which the character of the structure of the teeth raises a question as to the adapt- ability of gold, the physical and nervous resistance of the patient is generally below that which would enable him to endure the ordeal connected with the thorough completion of the work in harmony with the high standard impressed by the continued advancement which has taken j^lace in dentistry. The tendency to caries of the teeth is a general consideration to be held in view in determining the propriety of employing gold. When the enamel is hard, the dentin solid, and the general tone of the health excellent, there can be no doubt that the inherent qualities of gold constitute it the most nearly permanent material. When, on the contrary, the opposite conditions exist, gold becomes, in propor- tion to the prominence of the unfavorable states present, the most questionable material. No correct conclusion, however, can be reached without consideration of the state of the oral secretions and of the habits of the patient as to the care taken of the mouth. The first stage of decay of the teeth is the softening of the enamel which is brought about as the conse- quence of the presence of carbohydrates undergoing fermentation in secluded positions, which effects the solution of the enamel at these places and prepares the way for the occurrence of caries of the dentin. Hence a correct hygienic condition of the mouth is the most important requirement for the protection of the margins of the tooth adjacent to fillings intended to restore them. The reaction of the oral secretions in their bearing upon the duration of operative procedures has also much weight, since, when they have an acid reaction, as the consequence of the presence of fermenting material, this condition favors the continuance of the process. Only an appreciable degree of alkalinity can inhibit enamel solution unless the general and local hygienic conditions are favorable. Tin. — This metal, in the form of foil, shavings, and rolled into thin strips, while not much in use, should have a wider field than is accorded it. It possesses great softness, when chemically pure, and is readily adapted to the walls of cavities for the reason that it pre- sents less resistance since it does not harden under the mechanical force employed. For the same reason, when the cavity is overfilled, the con- densing appliances effect by the lateral movement of the mass a better and more easily procured adaptation with the cavity walls. For these reasons it possesses excellent preservative qualities. Tin is also a poorer thermal conductor than gold, and this is an important consideration when thermal irritation is to be avoided, and is of great value in deep cavities approaching dangerously near to the pulp. 170 FILLIXG MATERIALS. The objections to this metal are its color when exposed to view and its softness, which greatly lessens its value in positions where it may be subject to severe attrition. Its most important use is for the temporary teeth of children, where it may be easily inserted and readily condensed, and rapid i^rogress in its introduction may be made, producing good results. Except when freshly prepared, tin is not cohesive, a quality which cannot be restored by heat, as may be done with gold. AMALGAMS. Their Composition. — The essential metals Avhich enter into the com- position of the dental amalgams are silver, tin, and mercury. To these are added various metals in varying proportions to modify the " setting," the color, and the affinity for sulfur compounds. For these purposes gold is used to influence the rate of chemical combination, and it also affects the color. Bismuth, antimony, or zinc are added in order to modify the shade and also to lessen the affinity for sulfur. The effect of various proportions of the metals entering into the formulas u])on the working qualities of an amalgam is extremely puz- zling ; slight differences in proportions causing widely varying results. The order in which the metals are introduced into the crucible and the degree of heat to which the mass is subjected in the fusing process also affect the working cpialities. The Proportion of the Ingredients. — Valuable tables have been given by Dr. Black which indicate that a nearly definite ratio between the silver and tin should be maintained. This ratio is found to be approxi- mately as follows — Silver 65, Tin 35 — when only these two metals are used to make the alloy. ^A"hatever addition of a modifving metal is introduced should be of small quantity and should be at the expense of the percentage of the tin. The ingot of the alloy should be finely divided either by filing or by thin shavings made by turning them off in a lathe. When the commi- nution of the alloy is made immediately before using, amalgamation is more easily effected than when the filings are kept for any considerable time unless there is a disproportion of tin or gold. This has been attributed to oxidation of the particles taking place wliich would in- hibit the amalgamation. Silver not being an oxidizable metal under ordinary conditions, the cause of the tardy combination with mercury is to be found in tlie attachment of sulfids to the surface, and also to the retarding influences of occluded gases which also tend to retard amalgamation. More recent investigations by Dr. Black tend to the conclusion that the difference in capacity for mercury observed in freshly cut alloy and AMALGAMS. 171 that which has been cut for some time is due to the diiFerence in molec- ular arrangement of the alloy, l^rouoht about by the comminuting pro- cess, which has the effect of hardening the grains and condensing their texture in the same manner that hammering the ingot would harden the entire mass. By the application of sufficient heat the particles of alloy may be " aged " artificially, and this aging is presumed to be simply an annealing process. The capacity of the aged alloy for mercury is markedly diflPerent from that of the freshly cut alloy, as are also the working qualities of the resulting amalgam mass, the aged alloy form- ing a slower setting and much smoother working amalgam than that made from freshly cut alloy. For the further details of this subject see Chapter XI., on Plastic Fillings. The proportion of mercury should be in excess to such a degree as to giye decided plasticity, thus establishing complete amalgamation of the particles of the alloy. When the amalgamation is complete the redun- dance is forced out through chamois skin, or the mass is kneaded in a napkin or piece of China silk which forces through the meshes most of the excess. It is claimed that this method of conducting the amal- gamation effects an approximately correct atomic relation of the metals with each other ; it being held that the freer proportion of mercury during the mixing process tends to this result, as the redundant metal is carried out with the excess of mercury as it is expressed. The Distinguishing Features of a Good Amalgam. — An amalgam (1) Should be non-shrinking ; (2) Should haye edge strength ; (3) Should maintain lightness of color under the yarying oral conditions ; (4) Should tend to assume a spheroidal surface. A further qualification is that the surfaces of the material may not undergo electrolysis. Indisposition to shrinkage is secured by a close conformity of the alloy Avith the proportions above given . JEdge strength is a term which has not as yet had a clear defini- tion in respect to the causes which determine the deficiency of this quality. The maintenance of unchangeability of the surface is directly related to this important desideratum, as roughening and erosion of the margins is the result of molecular waste, which causes a ragged and unclean appearance of the edges and an apparent separation of the fill- ing from the borders of the cavity. The causes which produce this condition are slowly progressive and are continuous. This kind of erosion is most marked when contraction takes place, from incorrect preparation or improper ratio of the metals entering into the formula, or careless manipulation, when capillary defects are liable to occur at the margins. The most probable hypothesis to account for these observed changes is that the presence of accidental moisture, by inducing electrolytic 172 FILLING MATERIALS. action between the metal:^, l)rings about the erosion of the material immediately within tlie margin.^. In these cases the exposed surfaces generally suffer little waste, for the reason that they are subject to the continued moyement of the oral fluids, but it is often observed that entire fillings undergo a similar gradual loss and disappear. This result is common where there is an excess of gold or mercury. In some instances the aboye described hction takes place to a limited degree upon the whole surface in proximity with the dentin, when a residue is found upon the filling as well as on the surface of the dentin. The conclusion from these observed facts is that the securement of edge strength depends upon an approximation to the chemical ratio of the elements of the alloy. This Ayould appear to be most nearly secured when the material is subject neither to shrinkage nor expansion. Expan- sion under some circumstances might produce marginal space and there- fore lead to the same result ; for instance, if in approximal or buccal cavities the depth were greater at one division than another the expan- sion of the thicker part of the united filling would tend to raise the edge surrounding the shallow part of the cavity, and would then subject the edge of the filling to electrolytic changes. The maintenance of propriety of size and form depends largely, if not entirely, upon the influence of silver. When the proportion of this element becomes less than 60 per cent, of the formula, the tendency to shrinkage appears and holds a nearly direct relation with the diminu- tion. AVhen the ratio of silver advances above 70 per cent, the expan- sion becomes marked, and at 80 per cent, is excessive. Lightness of Color. — The means by which this property may be secured have not as yet been well determined and should be the subject of extended experimentation. Some of the so-called white alloys approximate stability in this respect, but the ratios of the modifying metal have not been determined. Bulging is observed when the proportion of mercury is abnormally large, and when slow-setting formulas contain an undue proportion of silver. Amalgam as a filling material is adapted to large cavities in the pos- terior teeth Ayhen the margins are too frail to permit gold to be con- densed ; for positions where mechanical force cannot be exerted with efficiency, notably the cavities of the third molar ; distal cavities of the second molar when of large size ; and the lingual cavities of the lower m<»lars. AVhcn the teeth are of deficient resistance and when the con- dition of the oral secretions favors tlie rapid progress of caries these limitations may be extended to cavities where otherwise gold would api>ear to l)e a more suitable material. As a material for the filling of the deciduous teeth amalgam possesses THE MINERAL CEMENTS. 173 superiority over any other substance, for the reasons that it can be intro- duced with less effort than tin and has greater durability than either the mineral cements or gutta-percha preparations ; the exception to its use here being when the conditions prevent retentive formation of the cavity. Concerning the /or?>i of ihe cavity adapted to amalgam, it is necessary that the retentive formation be equally exact as for gold, since many of the formulas in use undergo slight movement for some time after their introduction, during which there is liability of marginal displace- ment which may lead to the defects treated of under the section con- cerning " edge strength." Amalgam, while presenting in its appear- ance an unfavorable comparison with gold, is capable of rendering important service when every consideration is given to the require- ments governing its successful employment. To attain the best results in the use of the amalgams requires extreme exactness as to the ratios of the ingredients and great care in all the procedures connected with the formation of the cavity, the form of the filling, and the subsequent finishing process. The disqualifications of amalgam are its unsatisfactory color and the unknown character of the composition of the formulas as furnished by the depots of supply. THE MIXEEAL CEMENTS. Oxychlorid of Zinc. — This material, because of its lacking the quality of indestructibility, is contraindicated in all exposed situa- tions. It possesses, however, a considerable degree of antiseptic power, and for this reason renders valuable service in deep cavities not nearly approaching the pulp, or even here when the pulp wall of the cavity has been previously protected by a layer of gutta-percha or a disk of asbestos paper. In such cases, particularly on occlusal aspects, the cavity may be nearly filled, leaving a remainder the thickness of enamel to be completed with gold. For the filling of root canals and pulp chambers it offers the best solution of the problem of preventing septic changes in the devitalized dentin. After many years, fillings of root canals and pulp chambers of this material remain unchanged and are found clean and without -odor on removal — a result that is not presented by any other filling material which may be introduced in these situations. Here it is im- portant that the material be not mixed very thin, es])ecially on account of the danger of forcing it through the apical foramen. A further use of this substance is to influence the shade of devital- ized teeth by the color tone it imparts to the crown of the tooth on account of its whiteness. This is enhanced by the fact that it comes 174 FILLING MATERIALS. into exact contact and remains without change, a quality which cannot be given to gutta-percha or other cements. As a temporary filling to correct extreme sensitivity of dentin in situations or under conditions which forbid ordinary therapeutic treat- ment, oxvchlorid of zinc has considerable value. Here when the pulp is not closely approached it may be retained for several months with considerable advantage. To secure the best results the proportion of zinc chlorid should be greater than in the formulas used for ordinary fillings. Zinc Phosphate. — This material, because of its greater power to withstand the infiuence of the oral secretions, has a wider use than the preyiously described cement. It cannot, however, be depended upon for permanent uses. While in some instances it may remain for several years when the oral fluids are neutral and when every attention is given toward the attainment of cleanliness, it is nevertheless a deceptive sub- stance, since it is liable under temporary changes of the secretions to undergo solution, more particularly in situations near the gum. When placed in approximal cavities it is extremely liable to become fissured at the cervical margin and then permit carious action insidiously to take place. Unlike oxy chlorid of zinc, the phosphate has no antiseptic influence, hence it does not inhil)it decay of the dentin in its proximity. Its chief use is as a temporary expedient for filling cavities on labial and buccal surfaces, where, being under easy observation, it may be used with benefit. On account of its chemical solution by the oral secretions, however slow this may be, it requires frequent renewal. Zinc phosphate is also of value for filling the principal portion of large compound cavities where the teeth would be injured by the force employed in the condensation of gold, and as a desideratum to avoid the great amount of time required to fill large cavities with this metal. It also here imparts in some instances much strength to frail margins. In the cavities which early form upon the occlusal surfiices of the permanent molar teeth of children it is of great value, as here it is kept clean by the friction of mastication, and l)eing under easy observation can be renewed when this is required. When the child reaches the age to have permanent operations the margins may be shaped for the reten- tion of gold, and in this case the principal part of the cement should be allowed to remain. Zinc phosphate is of questionable use in pulp chambers as not hav- ing antiseptic pro])erties, and being porous it becomes after several years quite offensive. For the same reason it is inadmissible for canal fillings. Furthermore, for this purpose it is questionable, on account of its adhesiveness, whether it is (•a[)abl(' of being thoroughly introduced CAVITY LINING IN RESPECT TO PROXIMITY OF THE PULP. 175 into root canals. All things considered, it is for these purposes greatly inferior to oxychlorid of zinc. Cavity Lining in Respect to Proximity op the Pulp. As caries approaches the pnlp it reaches a period when the proximity of this organ is so close as to require much care to avoid irritation and probable congestion. Under these circumstances it is necessary to avoid thermal conduction and to exclude chemical influences. After disinfection of the dentin some substance the ingrediency of which is non-irritating and non-conducting should be selected to overlay the pulp wall of the cavity. Here choice must be made between gutta- percha and either of the classes of mineral cements. When the use of gold is preferable for the external portion of the filling, it is required that the foundation be sufficiently solid to with- stand the force to be applied to the gold. Hence one of the cements is here necessary. Previous to the placement of the cement, should the pulp be near, the surface should be covered with a thin solution of one of the resins to prevent the influence of the fluid element of the cement from producing irritation. Copal ether varnish, a solution of hard Canada balsam in chloroform, or the solution of nitro-cellulose in methyl alcohol sold as " Kristaline " or " Cavitine " are effective materials for this purpose. When the cavity is deep the layer of cement should be brought to the inner line of the retentive grooves. As soon as hardening takes place the metallic covering may be given. When the shallowness of the cavity will not permit a considerable layer of the cement, a metal cap covering the pulp wall of the cavity filled with the cement may be laid in place, the metal of the cap thus sustaining the force. These forms of cavity lining are of great utility, and should be regarded as of importance. Marginal Cavity Lining-. — When cavities are situated on approxi- mal surfaces of the teeth and extend high up on the cervical aspect so as to place them beyond the probability of efficient service with metal foils, and when the lateral walls of cavities are weak either by their thinness or by instability from defects of structure, some form of " lining " is necessary. In the one case, to ensure certainty of per- formance at the cervix ; in the other, to prevent injury. For the cervical part the choice is between (1) tin, (2) a combination of tin and gold, and (3) amalgam. Tin has the objection when superimposed above gold that it suffers waste, in most instances by electrolysis, to which the mixture of tin and gold is not liable. This latter combination — made by folding a layer of the tin within the gold foil — appears to give the tin protection. This 176 FILLING MATERIALS. combination is more plastic and more yielding than gold alone, and permits adaptation and consolidation in places difficult of approach. When used in connection with a matrix thorough consolidation may be effected without injury to the cervical margin when the tissues are not dense. When the color of a lining at the cervix will not be objectionable, a quick-setting amalgam answers extremely well, and may at the same sitting be followed by the completion of the operation with gold. In this situation, whatever the lining material, close conformity with the lines of the cervical form (tf the tooth must be assured. In many instances the lining and the completion of this portion of the filling sliould be effected before the rubber dam is placed, when the lining portion is for the time being considered in its relations as a part of the tooth. When it is necessary to use the mineral cements on approximal sur- faces of the posterior teeth for temporary purposes, the cervical border should be covered with a line of gutta-percha stopping, to protect this vulnerable part of such fillings from the exposure of this border by the solution to which they are there liable. . Lining Lateral "Walls. — For this purpose choice should l)e made of zinc j)hosphate, since it has the required strength and enters into the necessary adhesive union with the margins to give the required secur- ity. The layer should be kept within the extreme outer border of the cavity, to permit the metal filling to overlay the margin of the enamel. W^hen the cavity is deep the retaining groove may be farmed in the cement. A general summary of cavity lining is, that tliis procedure is required in proportion to the difficulty of effective approach, and for the safe treatment of teeth below the average of structural quality, and when the oral conditions are unfavorable to the permanence of restorative operations. CHAPTER IX. TREATMENT OF FILLINGS WITH RESPECT TO CONTOUR, AND THE RELATION OF CONTOUR TO PRESERVATION OF THE INTEGRITY OF APPROXIMAL SURFACES. By S. H. Guilford, D. D. S., Ph. D. The treatment of a cavity of decay by filling must have a twofold object in order to subserve its best purposes : first, the restoration of the affected jDart to a healthy condition ; and second, the prevention as far as possible of a recurrence of the lesion. The first is accomplished by the removal of all disintegrated tissue and the perfect filling of the cavity with a suitable and durable material. The second demands for its success a proper understanding of the cha- racter of the surfaces operated upon and their mechanical and physio- logical relations. While the simple filling of a cavity, if properly done, will generally prevent the extension of decay on exposed surfaces, the same operation on surfaces less favorably situated may utterly fail to subserve the desired end. The contiguity of the approximal surfaces of teeth greatly favors the retention of food and the harboring of micro-organisms, while at the same time it prevents the free cleansing movement of saliva be- tween them. For these reasons such surfaces, though originally per- fect in their continuity, are attacked by caries more frequently than any others, except the occlusal surfaces where continuity is broken by fis- sures and pits. When once affected by caries, their restoration by fill- ing is difficult owing to their inaccessibility, and while the operations on this account often lack the perfection that would otherwise be secured and the fillings consequently fail, the recurrence of decay is more largely due to the same influences that brought about the initial lesion. This being the case it is obvious that the original conditions must be changed if immunity from future decay is to be expected. This principle was early recognized and the first attempt to alter the con- ditions was by filing or cutting the approximal surfaces so as to free them from contact, on the principle of " no contact, no decay." Where all of the teeth were thus separated immunity from decay was generally secured, although at the cost of great loss of masticating surface, much 12 177 178 THE SELF-CLEANSING SPACE. disfigurement, and gubsequent serious injury to the gum and peri- cementum. Where only an occasional space of this character was made, the operation proved a failure because in a short time, through the pressure of adjoining teeth and altered occlusion, the mutilated teeth would again be brought into contact and the opportunity for decay be increased a hundredfold. With the recurrence of decay, cutting or filing would again have to be resorted to until but little of the teeth remained and they were eventually lost. On account of its unfortunate results the method was for a time abandoned, but in 1870 it Avas revived in a modified form through the teachings and writings of Dr. Robert Arthur. His method consisted in altering the form of the approximal surfaces of teeth by filing or grinding so as to change the point of ap- proximal contact from near the occlusal surface to near the cervical margin. This not only changed the normally convex approximal sur- face into a flat or plane one, but was also supposed to free it ti\)m further liability to decay by i)re venting the retention of food debris and render- ing the surfaces and spaces " self-cleansing." The method was measur- ably adopted by numbers of conscientious practitioners as a means of obviating a difficulty hitherto unsuccessfully combated. In a short time, however, it was discovered that its promise of success was not being realized, and it was also gradually abandoned. Its failure was due to its being wrong in principle, for, while it seemed to offer tem- porary relief, its after results were most disastrous. By leaving a shoulder near the cervical margin the point of contact was simply transferred from one point to another with the result that the latter point was far more liable to caries than the former one, owing to its position. ISIore than this, the exposed dentin on the cut surfaces, lacking the natural ])rotection of the enamel covering, was apt to be sensitive, and the fi)od crowding into the space and pressing upon the gum rendered it hypersensitive and eventually caused its recession. Tlie discomfort fi»llowing this unnatural operation, together with the increased liability to decay resulting from it, were sufficient to condemn the method and cause its abandonment. These failures to secure freedom from decay by an unnatural altera- tion of the forms of approximal surfaces led to a more careful investi- gation of the causes responsible for its recurrence on these surfaces, and the gradual adoption of more rational and scientific methods for its pre- vention. It was apparent to even the most casual student of compara- tive dental anatomy that the number and kinds of teeth fi)und in the jaws of man, their arrangement in the arches, and their general form were all such as to best subserve the wants and needs of the individual, but the more minute points of their external anatomy, their inter- NORMAL CONTOUR IN RELATION TO CARIES. 179 dependence and relation to one another, and the part played by the fluids of the mouth in the causation of caries under both original and changed conditions, had not previously been carefully inquired into. Under the old belief that contact caused decay it was thought that decay upon approxi- mal surfaces always began at the point of contact and that this was due to the fermentative changes occurring in food debris retained at this point. Investigation proved, however, that the points of contact be- tween teeth were not only free from decay, but more or less polished from slight motion of the teeth in their sockets, and that approximal decay always began just above the contact point, that is, slightly nearer the gum ; also that it could occur nearly as readily without the presence of food as with it. It was further noted that the normal contact of teeth on their approximal surfaces, which was formerly supposed to be essential only for mutual support, was equally necessary for the protection of the tender gum tissue from injurious pressure of food in mastication. Finally it was observed that those portions of the crown of a tooth that were beneath the gum margin or those above it that were constantly covered by saliva (as on the approximal surfaces near the gum) were always free from the beginnings of decay, and that the approximal and buccal or lingual surfaces, when faultless in structure, were first attacked by caries on a line corresponding with the point to which the fluids of the mouth usually rose. An explanation of this peculiarity was soon found in the fact that the saliva is usually alkaline and consequently protective of the parts covered by it, but at its surface, in a state of rest (as in sleep), this condition of alkalinity is changed to one of acidity — the calcium salts are dissolved and decay is begun. As a result of the foregoing observations and investigations it became apparent to the mass of conscientious Avorkers in the field of operative dentistry : 1st. That the natural form or outline of each tooth was the best for its particular function, and that to materially alter it was to lessen its usefulness and hasten its loss. 2d. That contact of ad- joining teeth was essential both to the comfort of the individual and the durability of the organs. 3d. That inasmuch as the teeth originally decay in spite of their natural form and contact, some plan would have to be devised by which, in their repair after decay, liability to a recur- rence of caries would be greatly lessened if not entirely prevented. To fulfil these requirements there was but one course left to pursue, namely, to fill approximal cavities in such a way as to restore the original contour of the surface, and, in all cases where the extent of decay was sufficient to warrant it, to extend the cavities so far over upon the buccal and lingual surfaces as to bring the enamel margins within the range of protective influences. 180 CAPILLARITY OF APPROXIMAL SURFACES. The rationale of original and recurring decay upon approximal surflices is readily made ap})arent by considering certain facts and prin- ciples of physics. When a tube is inserted in a liquid capable of wetting its surface the liquid will rise to a higher level within the tube than the surface level of the surrounding liquid. This phenomenon is known as capil- lary attraction, and is explained upon the principle of " surface tension of liquids." If, instead of a tube, two rounded or flat plates are im- mersed in the liquid, the same rising of the fluid between them will be noticed. The smaller the tube, or the nearer the two plates are together the higher will the liquid rise between them. Applving the principles governing these facts to the teeth and con- sidering them as bodies immersed in a liquid (saliva), it will readily be seen that if the approximal surfaces of the teeth were parallel and close together the saliva would rise to a higher level between them and cover more tootli surface than if they stood farther apart, and being re- tained in this narrow space with little opportunity for motion the saliva would soon assume an acid character and destruction of the tooth tissue begin. This is exactly what takes place upon appr(»ximal surfaces made flat bv filing, and will occur whether fillings have been placed in such surfaces or not. Normally, however, the crowns of the human teeth are more or less convex upon their approximal surfaces and touch each other only at the point of their greatest transverse diameters, which is near to and just above the occlusal surface. From this point their diameters gradually become less until they reach the cervical border, where they are smallest. This leaves a triangular interdental space with the base of the tri- angle at the gum, as shown in Fig. 152, in which the saliva will rise but a short distance owing to the se})aration near the gum and the consequent lessening of the capil- lary attraction. For this reason teeth preserving their normal forms are less liable to ap])roximal decay than they could possibly be under any siu.w iiig normal i ontact of otlicr Conditions. The earliest treatment of approximal sur- faces with a view to the prevention of caries consists in gaining access to them by wedging, and if found to l)e sujierficially affected by caries the removal of the injured structure and tlie ])erfect polishing of the surfaces. When cavities of moderate size are discovered tliey sliould be care- fully j)r{'par('d and filled, ])reserving tlie original contour as far as possible. Decay may recur, but it is less likely to do so with advan- cing age, increased density of tissue, and proper ])ro[)hyhictic treatment. CONTOURING AS A PROTECTIVE MEASURE. 181 Where the decay is of larger extent, however, we have it in our power to make such physical change in the parts affected as to render future immunity from decay reasonably certain. First, it is necessary to separate the teeth well by wedging, to so enlarge the cavities as to bring their lateral margins well out upon the lingual and buccal surfaces, and to extend the cervical margins of the cavities down to or beneath the free margin of the gum. Next, the fillings must be carefully inserted, built out to fully restore the original contour, and most perfectly finished. When this has been done and the teeth have returned to their former positions the approximal surfaces will be in a better condition to resist the influ- ences of decay than they originally were, for any changes in the char- acter of the saliva cannot affect the gold, and while the cervical border of the filling is protected by being constantly covered by saliva the lateral borders are so far out upon their respective surfaces as to be sub- ject to the cleansing influences of the lips and tongue. In addition to this, and scarcely less important, the restoration of contour on the approximal surfaces affords normal protection to the tender gingivae by preventing the lodgment and pressure of food upon them. The contour method of filling, based as it is upon physiological, anatomical, and mechanical principles, has become the accepted method of operating. Experience has proven it to be the only rational method of treatment of approximal surfaces, for by it we secure all the desir- able conditions of preservation of the natural outline of the teeth, necessary contact, immunity from future decay, and protection of the gum margins. Its practice involves some sacrifice of healthy tooth structure along the buccal and lingual aspects, as well as greater ex- penditure of time in filling and finishing, but the results compensate for both of these. To properly perform the operation of filling and restoration of approximal contour requires not only manipulative skill of a high order, but also an artistically trained eye in order that the restoration may in all respects correspond both in extent and form to the original outline of the tooth ; both of these requisites will be acquired through frequent repetition. In certain cases, as where the teeth originally were not quite in contact, the contour may be advantageously exaggerated in order to close the space, but it should never be less than normal or the result will not be satisfactory. In the filling of an approximal surface next to a space, as where a tooth has been lost, the necessity for full restoration of contour does not exist and is not absolutely demanded, although a more artistic result is secured by its performance in all cases. CHAPTER X. THE OPERATION OF FILLING CAVITIES WITH METALLIC FOILS AND THEIR SEVERAL MODIFICATIONS. By Edwin T. Darby, D. D. S., M. D. In the selection of a tilling- material the operator should consider the character of the secretions of the oral cavity, the position of the tooth to be filled, the extent of the diseased area, the physical structure of the tooth, and the strength of the cavity walls. A filling material must possess certain inherent qnaliiications, the most important of which are adaptability, indestructibility, non-conductivity, hardness, absence of shrinkage, harmony of color, and ease of manipulation. All of these are not to be realized in any one material, and yet some of the more im])ortant are to be found in a single metal or in a combination of metals. Lead possesses the cjuality of softness and is easy of adaptation but is readily oxidized when exposed to the air or the secretions of the mouth. Likewise tin possesses characteristics, such for instance as duc- tility and softness, low conducting power, and the ease with which it may be manipulated, which ])lace it in the front rank as a preservative of carious teeth, but it is inharmonious in color, and its very softness, which is so desirable in manipulation, is an obstacle to its use upon surfaces Avhere there is much attrition. The zinc phospJiafcH, which are com])osed of zinc oxid and phos})horic acid in solution, form a com- bination which at first attracted the favorable attention of the dental surgeon as possible substitutes for metallic foil fillings. They possess, owing to their plasticity, ease of manipulation, harmony of color, com- parative non-conductivity, and absence of shrinkage, many desirable qualities, but are lacking in one essential qualification, namely, inde- structibility. Gold. Gold, which has been used for about a century, has fulfilled in a more marked degree than any other material or combination of materials the rc(|uirenients sought for in a filling for carious teeth. It has one or two objectional)le features, such as high conductivity of heat and inhar- monious color. 182 GOLD. 183 Too much stress cannot be laid upon the question of its purity if the best results are to be obtained from its use. While it is claimed by manufacturers of dental gold foil that their products are absolutely free from alloy, it is nevertheless trne that but few specimens of dental foil show a fineness above 999. If this standard were always attained the operator would have little cause for complaint. So small a percentage of alloy as 1 in 1000 would not materially affect the working qualities of the product, but when this is increased to 4 or 6 parts per 1000 it manifests itself by harshness and intractability under the instrument. Great care should be exercised in the preparation of the foil, since so much depends upon its purity and cleanliness. For a detailed description of the process of manufacture, from the ingot to the beaten and annealed foil, the reader is referred to an article by a joractical foil- maker.^ In former times the dental surgeon was restricted to one form of gold for filling. This was foil ranging in thickness from 4 to 10 grains to the leaf, but as the requirements of the operator broadened the art of manufacture increased, and new preparations were offered, until to-day the most fastidious can find such as will please his fancy : foils ranging in weight from 4 to 120 grains to the leaf; cylinders of various sizes and composed of non-cohesive and semi-cohesive foil ; cohe- sive blocks prepared for use ; rolled gold, varying in thickness from No. 30 to 120, and crystal gold possessing great cohesive properties. These are the more important forms in which gold is offered the operator at the present time. Before entering upon a description of the classes of cases where each of these seems best adapted, it may be well to describe somewhat in detail the peculiar qualities which each form of gold presents when subjected to clinical use. Soft or Non-cohesive Foil. — Prior to 1854, when Dr. Robert Arthur discovered and promulgated the desirability of cohesive foil in certain cases, the operator used gold which possessed very low cohesive properties. Used as it then was, in the form of large rope, tape, or as cylinders, the property of cohesion would have been a serious objection, since there would be constant danger of the mass clogging and bridging in the cavity, and the cause of many unfilled places along the cavity walls. The terms soft and hard, when used to designate the kind of gold, are misleading, since all gold foil prepared from pure gold or gold that is nearly pure possesses great softness under the instrument. The distin- guishing characteristics between the two kinds of gold are the inability to make a certain kind of foil cohesive when exposed to a reasonable ^ American System of Denistry, vol. iii. p. 839. 184 THE OPERATION OF FILLING CAVITIES. degree of heat, and the ability to render another make of equal purity cohesive by the application of a similar degree of heat. It has been claimed by some manufacturers of dental gold foils that they are able to procure from the same ingot samples of non-cohesive, semi-cohesive, and extra-cohesive gold, attaining these physical properties of the mate- rial without alloying with other metals. This has led to the belief that, since absolutely pure gold possesses inherent cohesive properties, some metallic salt or other foreign substance has been deposited upon the surface of the leaf of non-cohesive foil which has the power of pre- venting the union of the surfaces of the foil when contact is sought. It has been surmised that a thin him of iron has been deposited upon the surfaces of the leaf of non-cohesive foil, for the reason that if a leaf of such foil be melted into a globule, it presents a reddish brown appearance, which is not true of the leaf of cohesive foil when melted as above. Much of the so-called non-cohesive foil offered for sale is not, strictly speaking, of this variety, as the application of moderate heat will render it quite cohesiv^e. It possesses the softness peculiar to pure gold foil, but it should not be classed with the variety which does not weld with other particles of the same metal except when subjected to great heat. It has been claimed by some that non-cohesive foil has no place in dental practice — that any tooth which can be filled with gold may be filled with cohesive foil. This statement may be true in the main, but it is also true that many teeth having strong cavity walls can be just as well filled where a large portion of the filling is made with non-cohe- sive foil, and with a great saving of time. Adaptation, not hardness, constitutes the saving (|uality in cavity filling. As most non-cohesive foil is prepared in the form of sheets and is placed in books containing one-eighth of an ounce, the operator is compelled to prepare it in some form suitable for introduction to the cavity. The size and shape of the cavity will be some guide as to the best method of preparing the gold. The narrow tape, the mat, the tightly rolled cylinder, and the roll or rope are the forms best adapted for the use of non-cohesive gold foil. The tn the kid strip between the two pieces of board, and by bringing the two surfaces of the kid in contact the foil is rolled between them. The undressed surface of the kid should be the one upon wliich tlie gold is rolled. Ropes thus made may be cut in lengtlis to suit the size of the cavity to be filled, and, as gold thus pre- pared has great softness and ease of adaptation, it may be inserted in quite large pieces if plenty of condensing force be applied to it. Cohesive Gold Foil. — All gold which has ])een refined by any of the ordinary methods and is in a pure state may be said to Ijc cohesive. Nor is absolute freedom from alloy an absolute necessity. It has been shown that softness is dependent upon purity, but a foil may contain quite a percentage of silver, copper, palladium, or zinc, and yet its cohesion may not be impaired. It may also be alloyed or combined with ])latinum and not lose its cohesive properties. It is, however, desirable that cohesive gold be pure, since the smallest percentage of alloy destroys its softness. AYhen two sheets or laminte of freshly annealed foil are brought into contact and slight ])ressure apjdied, they form a permanent union and are practically inseparal)le. It is this property in gold to which the term cohesive has been applied. But this property in gold is soon lost by the occlusion of gases or impurities of any kind, which may be deposited upon the surface of the gold.' Experiments have demonstrated the fact that if the gold be sub- jected to the fumes of ammonia, hydrogen, hydrogen carbid, hydrogen phosphid, or sulfurous acid gas its cohesive property is quickly de- stroyed, but this property may be restored by heat except in the case of sulfur or phosphorus fumes. Hence the importance of excluding the gold as much as possible from the atmosphere, especially during the Avinter mouths when gases arising from the combustion of coal are most liable to 1k' ])resent in the operating room. Dr. Black has shown that ammoniacal gas has the power to prevent the deleterious influence of other gases, and recommends that the foil be subjected to the influence of carbonate of ammonia by keeping it in a drawer Avith a bottle of that salt. The advantages of cohesive foil cannot be overestimated. AVith its introduction in 1855 began a new era in the possibilities of saving cari- ous teeth. 0])erations which were deemed impossible by the use of non-cohesive foil were made comparatively easy by the intelligent use of cohesive foil. The restoration of broken-down or badly decayed ' G. V. Black, Ih-ntnl f\m,vm, vol. xvii. ji. 138. GOLD. 187 teeth became the common practice in the hands of the skillful, and mod- ern methods of practice coupled with intelligent use of this form of gold have made it possible for the operator of modern times to do that which the earlier practitioner deemed impossible. The beginner, however, must not lose sight of the fact that cohesive foil cannot be worked after the same methods as non-cohesive foil. To use cohesive foil in the form of mats or cylinders or in tightly rolled ropes would mean inevitable failure in adaptation. The very property which renders it valuable in the restoration of broken-down teeth and in surfacing is the one which would condemn it if used carelessly in the interior of inaccessible cavities. Non-cohesive gold may be introduced into a well-shaped cavity in large masses, and because of its softness and ease of adaptation may be made to touch all points of the cavity walls if persistent pressure be applied. On the contrary, cohesive foil should be introduced in small pieces, the first of which should be well anchored in a retaining pit or groove and each subsequent piece welded thereto. There are several modes of preparing the beaten cohesive gold foil for the cavity, and good results are obtained by either of the following methods. A loosely rolled rope made of a quarter sheet of No. 4 or 5 foil may be cut into lengths varying from one-eighth to one-quarter of Fig. 156. I I A Ribbons and strips. an inch, and after annealing carried to the cavity upon the point of the plugging instrument. Or a leaf may be folded with a spatula four 188 THE OPERATIOX OF FILLTSG CAVITIES. times, making a broad ribbon, which may be cut either lengthwise or crosswise of the ribbon in pieces one-sixteenth or one-eighth of an inch in width (see Fig. 156). This is a very convenient manner of working cohesive gold. Or the heavier foil up to Xo. 20 or Xo. 30 in thickness mav be cut in strips of a single thickness and of the widths above indi- cated, and after annealing may be packed into the cavity — the essential idea being ever in mind, that but a small quantity of the gold shall he under the instrument at a given time. Cohesive gold which has been rolled instead of beaten to the desired thickness is much prized by some. It has been asserted that greater softness is obtained Avhen gold has been thus prepared. Such gold should not be more than Xo. 20 or Xo. 30 in thickness to insure the best results. It should be cut in narrow strips and after annealing be folded back and forth as rapidly only as each previous fold has been well condensed. Good results are only attainable if each lamina be thoroughly welded. The loosely rolled cylinders and blocks which are prepared by some dealers and oifered as cohesive gold are usually but slightly cohesive, and if used in this form, without re-annealing, may be packed in the interior of cavities without danger of clogging, but if freshly annealed they are contraindicated, since there is more or less danger of imper- fect union of all particles af the gold. It is questionable whether the larger sizes are admissilile when the filling extends beyond the cavity walls and great solidity is an essential factor. Crystal Gold. — This form of gold was introduced by ]Mr. A. J. AVatt in 1853, and as prepared at the present time is one of the best preparations of cohesive gold. When first brought out the method of manufacture was faulty, since it was difficult or impossible to rid the spongy mass of nitric acid which Avas used in its preparation, but since Mr. Watt adopted electrolysis instead of chemical precipitation the objectionable features no longer exist. Gold thus prepared manifests great cohesive properties, and when used with care as beautiful opera- tions can be made with this gold as with any form of cohesive foil. The operator should not lose sight of the fact that the gold is to be intro- duced into the cavity in small quantities. Should failure attend its use, it would doubtless be from the attempt to introduce it too rapidly. Gold of this variety comes in bricks containing one-eighth of an ounce each, and is either torn apart in irregular-sha})ed pieces or cut by means of a razor into small cubes. This gold should be excluded as much as possible from the atmosphere and when used should be well annealed, although when recently made it is quite cohesive. There is no prepara- tion of gold better adapted for starting fillings in shallow or irregular cavities, or for surfacing fillings. Many operators make use of it always for starting and for lini-hiiig fillings. ANNEALING GOLD. 189 Crystal Mat Gold. — This is another form of crystal gold, and differs from that previously described in that it presents a more compact form, the crystals appearing smaller and matted together. It breaks and crumbles under the instrument to a greater degree than the other, and possesses no desirable qualities which the other has not. If it has any merit it is for finishing the fillings upon occlusal surfaces, or such surfaces as are easy of access, or it may be used in conjunction with amalgam. Gold and Platinum. — This form of gold has found much favor with many practitioners for the restoration of incisal edges, or where for any reason great hardness of surface is desired. An ingot or bar of pure gold and one of platinum are " sweated " together and then rolled to the desired thinness, usually about that of No. 20 or No. 30 foil. It is then cut into narrow strips, freshly an- nealed and used after the same manner as heavy foil. The commingling of the platinum with the gold gives the filling a tint more nearly the shade of the tooth, and for this reason it is much used upon labial sur- faces and in mouths where the teeth are much exposed. Gold thus combined with platinum is much more rigid than gold alone, and is contraindicated for making the bulk of most fillings. The best results are obtained by its use when the mallet is used quite generally in its condensation. Annealing Gold. After the manufacturer has reduced the gold to the desired thinness by beating, his last act before booking it is to heat it ; this is termed annealing. The object of this is to remove any harshness which has been given to it by the process of beating. All metals become more or less stiff or rigid by hammering, but become soft again by the applica- tion of considerable heat. Gold foil which has been recently made and excluded from the atmosphere, or certain gases, as previously men- tioned, may present sufficient cohesive properties to weld satisfactorily, but this property is soon lost, and reheating becomes necessary if it is desirable to get union of the various layers. Most operators make use of an alcohol flame for annealing gold ; others a small Bunsen gas burner. Some hold the piece of gold to be annealed in the direct flame or a little above it ; others place the gold upon a tray of Russia iron, mica, or platinum and hold this in the flame of the lamp or gas jet. This latter method is safest, since there are apt to be impurities in the flame dependent upon a charred wick, a particle of phosphorus dropping into the wick from the burning match, or, in the case of the gas jet, imperfect combustion which might give either 190 THE OPERATION OF FILLIXG CAVITIES. carbon or sulfur deposits upon the surface of the gold. All or any of these accidents would impair the working qualities of the gold. The most satisfactory method of annealing gold is by the use of the Electric Annealing Tray. Such a device has been invented by Dr. L. E. Custer, and is shown in Fig. 157. By this method the gold can be Fig. 157. Custer's electric annealing tray. heated to any desired degree and with a uniformity not easily attained by the methods generally used. The working qualities of foil whether non-cohesive or cohesive are greatly enhanced by the application of heat at the time of using. Gold that is absolutely non-cohesive is made tougher by annealing and yet its softness is not impaired, while cohesive gold may be made either slightly or decidedly cohesive according as much or little lieat may be applied to it. It is the ])ractice of many operators to use the gold but slightly cohesive when filling cavities sur- rounded by str(^ng walls, and the gold known as semi-cohesive, in the form of loosely rolled cylinders, is much used. As tlie filling approaches completion the cylinders are heated and additional cohesive property imparted to them. But when the object is the restoration of contour or building up of teeth which have been broken, the gold shcjuld be heated but little short of redness in order that the greatest cohesive property mav be realized. Introduction of the Gold, and Manner of Adapting It to THE Walls of the Cavity. It has been shown in Chapter VI. that few cavities are of proper shape for retaining tiie filling when the decay alone has been removed. Most cavities require to l)e given a retentive shape so that the filling shall not be dislodged during its introduction or by mastication or otherwi.se after its completion. In former times, when the operator was restricted to one form of gold and that the non-cohesive variety, he was compelled to prepare his cavities accordingly ; but at the present time, when the variety is almost endless, he can shape his cavity with a view INTRODUCTION OF THE GOLD. 191 to conserving tooth structure, and when he has given it a shape to please him he can select, from the many, a special form of gold that will meet his requirements. There are certain principles involved in the packing of gold which must be borne in mind, and the operator should study these before intr^ ^ ! Til ^1 fl 11 14 15 16 17 Dr. Bing's set of pluggers. 18 19 •20 This set should be supplemented by a small and a medium sized foot-shaped condenser (Fig. 159), for packing ^lo 159 cylinders, mats, or ])loeks against the cervical Avail. The handles of instruments u,d throughout with cohesive gold. Each cavity independent of the others should have retentive shape, so that in the event of one filling being displaced the other will remain intact. As a rule it is better to fill the cavity on tlie labial surface first, because the first pieces of gold are more easily anchored in an accessible COMPOUND CAVITIES. 203 Fig. 177. Fig. Hi cavity, and because also of the danger of displacing the gold in the approximal cavity when filling the channel connecting the two fillings. Every possible care should be exercised in packing the gold in cavities of this description. The gold should be made thoroughly cohesive by recent annealing, and be used in pieces sufficiently small to prevent clogging. Such operations are more or less exposed to view, and the greatest degree of artistic skill should be bestowed upon them to render them as pleasing as possible to the eye. The original outline of the tooth should be restored with the gold, because it pre- sents a better appearance than a space between it and the adjoining tooth (Fig. 177). Classes K and L. — Cavities upon the mesio-Ungual or disto-lingual surfaces of the teeth are filled in precisely the same way as those described under classes I and J. If the cavity be of con- siderable depth, non-cohesive gold may be used as part of the filling, but in any event the bulk of the filling should be made of cohesive foil (Fig. 178). Classes M and N. — Mesio-indsal ; Disto-incisal. — Cav- ities situated upon the approximal surfaces of the incisors and becoming confluent with one on the incisal edge require great care in the matter of packing gold. It is often an advantage to have the cavity on the approximal surface unite with a natural or an artificially made one upon the incisal edge, because much better anchorage can be obtained in such cavities. Cohesive gold prepared in the form of ribbon or in pellets or cohesive cylin- ders, if loosely rolled, may be used. The better method is to fill the undercut at the cervical border of the cavity first, and then bring the gold toward the incisal edge as squarely as possible, keeping the mass on a line with the labial and palatal walls. The operator feels a sense of security when he is able to an- chor such fillings in an undercut or retaining pit on the incisal edge. In teeth with broad incisal edges there is ample opportunity to make a strong retaining hold, but where the edge is narrow a lateral cut into the palatal wall one-third back from the incisal edge affords a strong and secure hold for that portion of the filling. Operations of this class require great thoroughness in the packing of the gold. It should be very cohesive and when possible condensed with some form of mallet (Fig. 179). Class 0. — Mesio-disto-incisal. — Where both approximal surfaces and the incisal edge are united in one cavity, the better plan is to begin the filling at the undercut near the cervical border of the distal cavity, Fig. 179. 204 THE OPERATION OF FILLING CAVITIES. and build the gold squarely down as in classes M and N until the in- eisal edge is reached, thence across the incisal edge, then fill the mesial cavity after the same manner, uniting the three fillings at the mesio- incisal corner. It is better to insert such fillings with an electric or a mechanical mallet, as there is always dan- ger, when packing across the incisal edge by hand pres- sure, of pushing one or the other of the fillings out of the approximal surfaces. Mesio-disto-incisai jf jjq accident occurs in the packing of the gold a fillings. . ... filling thus made is very secure, for its form is like a staple and each portion helps to bind the others securely in the triple cavity. Non-cohesive gold should form no part of such fillings (Fig. 180).' Bicuspids and Molars. Class P. — Mesio-ocdusal. — The filling of this class of cavities offers no serious difficulties provided sufficient space has previously been ob- tained. As it is desirable to restore with gold the original outline of the tooth, sufficient space to do this in is a necessity, and the operator will soon learn that he can only accomplish good results in proportion as he recognizes the importance of this preliminary. The cervical border is the vulnerable point for recurrence of decay, and imperfection here in the matter of packing the gold means speedy failure of the filling, hence the importance of a perfect joint between gold and tooth. This may be obtained by either non-cohesive or cohe- sive gold if due care be exercised in their use. Where the cavity has not great depth and the retaining grooves are also shallow, no better method of laying the cervical foundation can be adopted than by the use of Watt's crystal gold or the " Velvet " cylinders, which possess great soft- ness and some slight cohesive properties. If the operator has had some experience in working non-cohesive foil he will do well to use a mat of non-cohesive foil at this point, allowing the mat to extend some- what beyond the cervical border of the cavity. This may be followed by another mat or two, after which they should be malleted to place, a foot-shaped plugger point being used. The upper third or even one- half of the cavity may be filled after this method. He should then begin the use of cohesive gold. The two kinds can be incorporated as previously described and the filling completed witii gold which has been freshly annealed. It is always better to insert too much rather than too little gold, as the operator can shape the contour according to his fancy or to the necessities of the case. The occlusal portion of the filling should be thoroughly condensed, COMPOUND CAVITIES. 205 Fig. 181. as much depends upon this for holduig the filling in place. Great hard- ness is also essential to prevent battering in the act of mastication (Fig. 181). Class Q. — Disto-occlusal cavities may be filled in precisely the same manner as those situated upon the mesio-occlusal surface. The difficulties are slightly greater because these cavities are not so accessible. Cavities of this description can be greatly simplified by the use of the matrix. This little device converts compound cavities into simple ones, and when used with care and judg- ment facilitates the operation of filling to a wonderful degree. It will be observed in the Jack matrices (as shown in Fig. 182) that provision Fig. 182. Approximo-oeclusal cavities. The matrices of Dr. Louis Jack. has been made for contouring the filling. If this style be employed the operator must study the outline which he desires his filling to assume and select his matrix accordingly. He must have previously obtained ample space between the teeth for the placement of the matrix. When put in place the matrix should be thoroughly fixed against the tooth to be filled, with wedges of orange wood previously dipped in Fig 183. Loop matrices. moderately thick sandarac varnish. This will keep the wedges from slipping. A very good way of fixing the matrix is to pack between it and the adjoining tooth some quick-setting oxyphosphate of zinc. If the part be thoroughly dry the cement will become adherent to the matrix and the adjoining tooth and the matrix will thus be made secure. 206 THE OPERATION OF FILLING CAVITIES. Whenever the matrix is to be employed it must be understood that an important feature is absolute fixation of the device, otherwise the ope- rator will suffer continual annoyance throughout the operation. AVhere there is sufficient space between the adjoining teeth for a band matrix the operator will find great satisfaction in their use (these Fig. 184. Brophy's band matrices. are shown in Figs. 184, 185), but as most teeth are smaller at the neck than at the occlusal surface, there is often difficulty in adjusting the Fig. 185. i^^ U 'Oi :ii y Guilford's band matrices and clamps. matrix to that portion of the tooth : a wedge used as previously described will often overcome this difficulty. A modification of the band matrix has been devised by Dr. Guilfinxl, and is .shown in Figs. 185, 186. It will be seen that space upon both sides of the tooth to be filled is unnecessary, as the little clani]) binds the matrix to the tooth. Another style of matrix, and one admirably adapted to many cavities in the bicuspids and m(»lars, has been intro- duced by Dr. W. A. Woodward, and is shown in Fig. 187. It will be seen that this matrix has two screws which are driven against the COMPOUND CAVITIES. 207 adjoining tooth and keep the matrix firmly in place and at the same time act as a separator. If the operator feels that he has insufficient space, as his filling progresses he can occasionally tighten the screws and gradually gain space between the teeth, which is of value when he is ready to dress down and polish his filling. Several sizes of these should be at hand to meet the exigencies of individual cases. It has been said that the matrix converts a compound cavity into a simple one. This is accomplished by making of metal a temporary fourth wall to the cavity. It must be borne in mind, however, that Fig. 186. Examples showing uses of matrices. the use of the matrix does not lessen the care which should at all times be exercised in the packing of the filling. Direct pressure against the disto-buccal and disto-lingual borders of the cavity cannot be as well obtained when the matrix is used as when it is not, hence the importance of having the matrix so adjusted that these walls may be accessible. Cavities of this variety seldom require retaining pits. The cavity is supposed to be of a retentive form. If the matrix has been made to fit the cervical border of the cavity and is thoroughly wedged against it, the filling may be started with mats of non-cohesive foil or with loosely Fig. 187. rium ; a sub-chemical compound, or a mechanical mixture — altliough this latter is rare, as mercury exhibits some degree of affinity for all metals. There are two possible ways in which mercury brings about the S(jlution of other metals : First, by a chemical affinity for the metals; second, by lowering the melting-point of the solid metal, forming an alloy whose melting-point is higlu'r than that of a mean of the constitu- Fig. 204. « = » » T I __ J NATURE AND PROPERTIES OF AMALGAM. 221 ents. The former is the explanation more in accord with the observed phenomena relative to the combination. Physical Properties of Araalg-ams. — As a class amalgams have defi- nite physical properties. First, that of hardening ; and for some time subsequent to apparent hardening, nearly all of them undergo change of voliune and form. The change of volume may be either contraction or expansion. Contraction and Expansion. — In contraction the mass tends to assume the form shown in Fig. 204. It has been shown by Dr. Black ^ that the extent of this contraction is due to several factors : 1. To the composition of the pri- mary alloy. All other things being equal, an alloy of 65 per cent, silver, 35 per cent, tin, represents about the fixed point where there is a minimum ^. ^ , , . , i Diagram of amalgam shrinkage. of shrinkage. As a class, alloys con- taining less than 65 per cent, silver make amalgams which contract ; those containing more than 65 per cent, silver make expanding amalgams. 2. To the amount of mercury used in amalgamation. There appears to be a definite percentage of mercury which produces the greatest strength of an amalgam mass ; moreover, the percentage which produces the maximum strength increases the shrinkage of the shrinking formulse and increases the expansion of the expanding formulae. Surplus mercury in the amalgam mass can reduce neither the expansion nor contraction of the amalgam mass. While an excess or deficiency of mercury in- creases the shrinkage or expansion of an amalgam (according as the percentage of silver is 65 — or 65 +), these volume changes cannot be overcome by the percentage of mercury. An excess or deficiency of mercury weakens an amalgam. It would appear that the conditions which bring about the most perfect union of the metals produce the greatest changes of bulk in those formulse in which changes of bulk occur. An alloy the amalgam of which neither shrinks nor expands cannot be made to do so by changes in the amount of mercury em- ployed. 3. A strong controlling factor has been found to be the evenness of distribution of mercury and alloy throughout the amalgam mass. An increase of the ratio of silver above 70 per cent, is followed by an enormous expansion of the hardening mass. It had always been noted that the amalgam made of a coin-silver alloy bulged from the walls of ^ Dental Cosmos, 1S95, vol. xxvii. p. 637. 222 PLASTIC FILLING .MATERIALS. a cavity enclosing; it. This alloy contains, as stated, 90 per cent, of sil- ver. The appearance of an expanded amalgam is similar to that of ice at the mouth of an iron tube in which the water has been frozen. Copper amalgam is the only alloy tested by Dr. Black which under- went no change of form in hardening. " Flow " of Amalgam. — A property attributed to certain amalgams, that of spheroiding, has been shown by Dr. Black to be without exist- ence. The bulu-iny; of amalii'ams from the orifices of cavities was held to be due to the tendency of the mass to assume a spheroidal form, hence the term spheroiding. Tests show^ed the appearance to be delusive, the phenomenon being due to expansion and not to a spheroidal tendency. In addition to the properties of contraction and expansion the same investigator has discovered the property, hitherto unsuspected in amal- gams, that of flow. The property of flow — i. e. change of mass form, from molecular motion under stress — had been observed in the majority of metals, but as found in amalgams it has a unique expression. Instead of being limited to a definite degree, proportioned by the stress applied, it has been found that amalgams yield repeatedly to the same amount of stress when applied at intervals, as in mastication, or yield continuously when the stress is constant. The process appears to be without limita- tions. It is at zero in copper amalgams ; next less in amount with alloys containing 55-60 per cent, of silver with 5 per cent, copper and the remainder tin. It will be readily seen that this property exercises a great influence upon the integrity and adaptation of an amalgam filling. The notes quoted from Dr. Black were compiled from studies made of amalgams whose exact chemical com]K)siti()n had nf)t been actually tested by the investigator. Later experiments ' made with alloys pre- pared with the utmost care and exactitude by the investigator himself, gave widely different results (particularly as to the effect of adding a third or fourth metal to the basal alloy) in the direction of both flow and shrinkage. The first series of experiments which appeared to show an enormous increase of shrinkage and flow together with a lessening of ^'(V^i.^ strength, by the addition of a third or fourth metal (except copper, which the latest experiments still show to lessen flow and increase rigidity) were not confirmed when Dr. Black experimented with alloys made by himself, and an additional and unsuspected factor was taken into consideration, viz. the influence of heat upon the alloy. It has been noted by Dr. J. Foster Flagg^ that alloys which were freshly (!ut possessed working ])roperties different from the same alloys when " old cut," or when aged. Dr. Black's observations appeared to confirm this, and his later experiments were directed toward deter- mining the cause underlying the change. Motion, whicli was said to ' iJentdl Cosmos, December, 1896. ^ Plctslirs and Phistic Fillings. NATURE AND PROPERTIES OF AMALGAM. 223 bring about the change, was found to have no influence. After exhaus- tive and conckisive experiments it was ascertained that the change was due to a molecular alteration of the cut alloy, through a process of an- nealing — /. e. heat was the agent producing the change. The degrees of heat applied ranged from 130° F. to 212° F. It was found that the amount of time during which an alloy was subjected to the action of heat, governed the extent of tempering ; for example, alloy subjected to a temperature of 130° for a given period, had the amount of amalgam expansion reduced a given amount ; if the heat were maintained for a longer period the expansion was corre- spondingly decreased. Each formula has its zero point beyond which tempering has no effect. In general terms, it was found that alloys in amalgams which expanded in hardening had the extent of expansion reduced by anneal- ing ; those which contracted had the contraction increased. Alloys which were without alteration of volume unannealed, shrank when annealed. The following tables will show the extent of change produced by annealing. It Avill be noted that the alloy of 72.5 silver, 27.5 tin, ex- hibits the minimum contraction after annealing. It will also be observed that less mercury is required to effect amalgamation in the annealed alloy .^ Amalgams made from annealed alloys have both their flow and crushing stress slightly increased. I. Exhibit of Unmodified Silver-Tin Alloys. Formula. How prepared. Per cent, of mercury. Shrinkage. Expansion. Flow. Crushing stress. Silver. Tin. 40 60 Fresh-cut. 45.78 6 7 40.15 178 40 60 Annealed. 34.14 9 3 44.60 186 45 55 Fresh-cut. 49.52 4 8 25.46 188 45 55 Annealed. 32.13 11 1 28.57 222 50 50 Fresh-cut. 51.18 2 2 22.16 232 50 50 Annealed. 37.58 17 1 21.03 245 55 45 Fresh-cut. 51.62 2 2 19.66 245 55 45 Annealed. 40.11 18 17.53 276 60 40 Fresh-cut. 52.00 1 9.06 239 60 40 Annealed. 39.80 17 14,10 297 65 35 Fresh-cut. 52.00 1 3.67 290 65 35 Annealed. 33.00 10 5.00 335 70 30 Fresh-cut. 55.00 14 3.45 316 70 30 Annealed. 40.00 7 4.67 375 72.5 27.5 Fresh-cut. 55.00 42 3.92 275 72.5 27.5 Annealed. 45.00 3 3.76 362 75 25 Fresh -cut. 55.00 60 5.64 258 75 25 Annealed. 50.00 6 5.40 300 ^ For a full exhibit of this stupendous work of Dr. Black' s, the reader is referred to his contributions in the Dental Cosmos for 1S95 and 1896. 2 Black, Dental Cosmos, 1896, p. 982. 224 PLASTIC FILLING MATERIALS. II . Exhibit of Modified Silver- Tin Alloys} Formulae. i 1 How pre- Per cent. Shrinkage. Expansion. 1 Flow. Crushing Modifying metal. 1 Silver. 1 Tin. pared. of mercury. stress. 65 35 Fresh-cut. 52.33 1 3.67 290 65 35 Annealed. 33.00 10 5.00 335 66.75 33.25 Fresh-cut. 51.52 4 3.35 329 66.75 33.25 Annealed. 33.53 7 5.06 380 Gold 0. 61.75 33.25 Fresh -cut. 47.56 1 4.62 330 Gold 5. 61.75 33.25 Annealed. 30.35 7 6.07 395 Platinum 5. 61.75 33.25 Fresh-cut. 51.87 9 9.68 273 Platinum 5. 61.75 33.25 Annealed. 37.33 7 8.20 352 Copper 5. 61.75 33.25 Fresh-cut. 53.65 23 2.38 343 Copper 5. 61.75 33.25 Annealed. 35.60 5 3.50 416 Zinc 5. 61.75 33.25 Fresh -cut. 56.65 68 1.83 290 Zinc 5. 61.75 33.25 Annealed. 40.65 9 2.07 345 Bismuth 5. 61.75 33.25 P'resh-cut. 46.26 4.78 288 Bismuth 5. 61.75 33.25 Annealed. 23.67 6 5.58 308 Cadmium 5. 61.75 33.25 Fresh-cut. 57.57 100 6.40 225 Cadmium 5. 61.75 33.25 Annealed. 47.25 5 3.54 290 Lead 5. 61.75 33.25 Fresh-cut. 44.17 1 4.88 290 Lead 5. 61.75 33.25 Annealed. 32.76 10 7.18 276 Aluminum 5. 61.75 33.25 Fresh-cut. 65.00 445 Aluminum 1. 64.5 34.5 Fresh-cut. 46.98 166 12.60 198 Aluminum 1. 64.5 34.5 Annealed. 38.26 48 17.90 213 Edge Strength. — What is termed the edge strength of an amal- gam is the degree of resistance an edge or angle of an amalgam mass oifers to force which tends to fracture it. Amalgams have heretofore been regarded as rigid crystalline masses, utterly devoid of malleability. The discovery of the existence of flow at once modifies all previous conceptions and data regarding edge strength, for it is evident that a corner or angle might not fracture and yet might flow under the stress of the impact of mastication, whereupon edge strength might be said to be great, and in reality be Init slight. In view of the existence of the property of flo\v, edge strength must be measured as rigidity, the antithesis of flow, and a high crushing stress. It has been shown that contraction or expansion, and flow, are the influences which would disturb the maintenance of size and form of an amalgam filling ; therefore, a minimum of shrinkage and How are the primary considerations in a satisfactory dental amalgam. Color. — One of the serious drawbacks to the wide employment of amalgam has been its ol)jectionable color, both in its original state and furthermore when it has suffered discoloration through the formation of oxid.-^ or sulfids upon its surface. The silvery white of amalgam in its most acceptable condition is not so harmonious a color as the yellow of gf>ld, which fact has led first to the restriction of the use of amalgams to such spaces as are not readily visil)le, where its original and subse- quently its altered color could not be a strong objection ; and, next, ' I'.lack, Dental C'o.smo.s, 1896, !>. 987. NATURE AND PROPERTIES OF AMALGAM. 225 has prompted a modification of the silver-tin formulse with the object of maintaining their original color. The discolorations are not alone upon the external surfaces of fill- ings, but frequently (and most frequently in improperly prepared and filled cavities) the discoloration affects the dentinal walls bounding the cavity (see Fig. 205). Fig. 205. staining of tooth structure with amalgam (Bodecker) : e, enamel ; d, d, dentin ; B, border of cav- ity ; s, solidified dentin along the border of the cavity ; r, reticulum brought forth by the amalgam. (X 500.) As shown in the illustration the discoloration may be deep. This danger is increased by leakage, when decomposing albuminous sub- stances generate HjS, and metallic sulfids are formed in marked quan- tities. This danger of dentinal discoloration is guarded against by 15 226 PLASTIC FILLING MATERIALS. interposing a barrier between the cavity walls and the amalgam prior to the insertion of the latter. The influence of individual metals upon color will be discussed later. Thermal and Chemical Relations. — As a conductor of thermal influence, amalgam is midway between gold and the basic zinc cements. As to the actual effects upon the vital tissues of dentin, it has never been demonstrated that amalgam exercises any specific influence, except that cadmium appears to cause, through the cadmium sulfid formed, a degenerative influence (Flagg), and copper has antiseptic properties (Miller, Fletcher). Chemically the dental amalgams are, to all intents and purposes, insoluble in the fluids of the mouth, the common solvent found in the oral cavity, lactic acid, affecting them but little. Classification of Amalgams. — Amalgams are divided into binary, ternary, quaternary, and so on, according to the number of constituent metals. The only binary amalgams employed in dentistry are those of copi)er and of palladium. Binary Amalgams. — Copper amalgam is made by adding freshly precipitated and washed metallic copper to an excess of mercury ; when solution is complete, the surplus mercury is expressed through chamois. The plastic residuum is then packed into moulds to make small tablets of the usual form in which it is dispensed. A better method, which yields a product of greater purity, is to pre- cipitate the copper directly into the mercury by electrolytic process. This may be done conveniently by pouring a quantity of mercury into a suitable glass vessel — a small battery jar, for example — and suspend- ing a thick plate of copper, by means of a wooden support, some dis- tance above the surface of the mercury. A saturated solution of cupric sulfate is then poured into the jar until the copper plate is com- pletely submerged. The cathode pole of a battery or other source of electrical current is then connected with the layer of mercury, and the anode with the copper plate. All that portion of the cathode electrode in contact with the cupric sulfate solution should be insulated with gutta- percha, and only the point which is in contact with the mercury left exposed. The passage of the current causes solution of the copper from the anode and deposits it in the mercury continuously as long as the foregoing conditions are maintained. The preci])itation should be continued until the mercury is saturated, which will be evidenced by the appearance of the characteristic reri<>r to expressing the surplus of mercury. ' It is to be recalled in this connection that Dr. Black's measurements are made with instruments of uneiiualled accuracy, those of previous observers witli comparatively crude instruments. ^ Private conuniiiiication. USE OF AMALGAM. 229 Use of Amalgam. It is to be understood that amalgam is to be employed only in those conditions and situations which clearly indicate it as the proper mate- rial. As a general rule, it is excluded from the ten anterior teeth of each jaw, although this rule is open to exceptions. Its anterior limit of application is usually regarded as the distal surface of the first bicus- pid. Its more general employment has been greatly reduced in many places since the introduction of what are known as combination fillings (see Chapter XII.), and by improvement in the forms and character of artificial crowns. The first class of cavities to which amalgam is applied are those which extend beneath the gum margin ; the second, buccal cavities ; the third, compound cavities ; the fourth, approximal cavities ; the fifth, cavities upon the masticating faces of the teeth. These are the classes in which gold is most difficult of introduction and of proper shaj)ing and finishing, in the order named. Amalgam should rarely or never be packed against dentinal or enamel walls without the interposition of a layer which will prevent either the discoloration of the dentin or the bluish api'carance noted when amalgam underlies enamel. The shaping of cavities for the reception of amalgam fillings (see Chapter VI.) should be done with such care as will give assurance of the permanent retention of the filling and the perfect sterilization of the dentin before and during its introduction. The separation of the teeth, removal of gum overhanging cavity margins, and breaking down of frail enamel walls by means of chisels, precede the filling. The rubber dam is to be adjusted where and when possible, with such care that an exclusion of the fluids of the mouth is assured during the shaping, sterilizing, and filling of the cavity. As Dr. Black has shown,^ much of the permanency of form of an amalgam mass depends upon the even distribution of the constituents ; it is evident that every aid to this end should be utilized, an important one being that the mass should be packed into a cavity having but one orifice, that for the introduction of the filling. With the data relative to dental amalgams which have been given, it is evident that a dental amalgam mass is by no means simple, but is a very complex body. If sufficient mercury has been used to effect solution of the alloy particles the mass will consist, first, of a quantity of a chemical amalgam — i. e. one in which the metals are united in atomic ratios — this being surrounded by one or more other distinct ^ Dental Cosmos, 1895, vol. xxxvii. p. 553. 230 PLASTIC FILLING MATERIALS. amalgams, each having its own time of setting and rate of contraction. If only enough mercury has been used to make a creaky mass the sur- faces of each alloy particle are covered by an amalgam of indefinite composition which acts as a cement binding the particles together. In this line the same experimenter has shown that mixing the alloy and mercury in a mortar by means of a pestle, wringing the surplus mer- curial solvent from the mass by means of heavy pliers, and packing the filling with steel burnishers are all influences which lessen the strength of the completed filling. The conditions are now a prepared and sterilized cavity ; any miss- ing wall required to give four sides has been replaced by a properly adjusted matrix (see Figs. 186, 187, Chapter X.). Fig. 206. Dr. Ueiij.sl's iiialrix. Matrices. — Matrices may be readily and quickly formed by cutting strips from a sheet of very thin sheet steel which has been annealed Img. '20 Fig. 208. Herbst pliers. and polished. By means of contouring pliers the matrix is given the correct contour, then wedged or tied into place. They must USE OF AMALGAM. 231 be so adjusted that they are immovably held during the filling ope- ration. A rapid method of forming a matrix is that of Dr. Wilhelm Herbst : A strip of German silver No. 33, wide enough to extend from the cervical margin of a cavity to its mouth, and long enough to more than embrace the tooth, is passed around the tooth (see Fig. 206) ; the strip is caught near its extremities by a pair of Herbst pliers (Figs. 207, 208) and drawn taut; the pliers pinch the metal into close adapta- tion to the tooth walls. Held by the pliers the matrix is with- drawn, the line of junction touched with zinc chlorid, and soldered over an alcohol or Bunsen flame with soft solder. The matrix is replaced upon the tooth, the rubber dam applied, and the matrix pressed against the cervical margin of the cavity by means of a wooden wedge. The matrices of Guilford and those of Brophy (Figs. 184, 185, Chapter X.) are operated upon a common principle ; the band which most nearly fits the periphery of the tooth is adapted, then drawn into close apposition with the tooth by means of the screw appli- ances. The matrix of Woodward is one of the most convenient. Its mode of application is shown in Fig. 187, Chapter X. The Miller matrix (Fig. 209) is useful and adapted for the class of cavities shown in Fig. 210, as held in contact with cervical mar- FiG. 209. gins through the action of the duplex spring leaflets. Fig. 210. When necessary a wooden wedge is forced between the leaflets. (For other forms and applications of matrices see Chapter X.) Mixing the Amalg-am. — It is usually recom- Miiier matrix adjusted. mended that the proportion of mercury and alloy be determined by weight. An amount of alloy is first weighed, then weighed additions of mercury are added to it sufficient to make a plastic mass, when the two are to be mixed together; the relative amounts of mercury and alloy are to be gauged and recorded for each formula of alloy. With the " submarine " alloy of Flagg — 60 silver, 35 tin, and 5 copper— the 232 PLASTIC FILLING MATERIALS. ratio is equal parts by weight of filings and mer- curv. When a mortar is used for making the amal- gam, one of glass and having a glass pestle (see Figs. 211, 212) is to be preferred. Mixing in the palm of the hand is a dirty process, the hand and fingers becoming much discolored by the metallic oxids. Fig. 211. Fro. 212. Glass mortar. Glass pestle. A rubber mortar (Fig. 213) to be received in the palm of the hand has been devised by Dr. Genese. In view of deductions from Dr. Fig. 213. Dr. (ienese's rubber mortar. Black's experiments this latter method of mixing is regarded as usually the preferable one. The filings are placed in the receptacle, the mercury is added, and the mass is triturated — if in a mortar, by the pestle, if in the rubber basin, by the forefinger guarded by a rubber finger-stall. When the USE OF AMALGAM. 233 amalgamation appears to be complete, the mass is transferred to the hand and kneaded, then pressed into a ball. It is next enclosed in stout muslin, or China silk as recommended by Dr. C E. Kells, Jr., and the surplus mercury expressed by wringing ; when no more mer- cury appears through the muslin, the button is removed : it should break with a clean, white fracture surface. Another method of mixing the filings and mercury is that of Fletcher. Filings and mercury are placed in a long glass tube which is shaken vio- lently until amalgamation is complete. The Packing Operation. — Several devices have been invented for the purpose of carrying the amalgam to the tooth cavity, one of the Fig. 214. most simple being shown in Fig. 214, and another in Fig. 215. An- other excellent instrument is shown in Fig. 216, one end having ser- Fia. 215. rated points which engage the soft amalgam, the other a plugger head. Numerous methods have been advanced and advocated for the pack- ing operation. The one commonly followed is that of burnishing the amalgam. This has been shown by Dr. Black to weaken the mass. A small piece, rarely more than a cube of ^ in. side, is carried to the deep- est and most inaccessible recess of the cavity and pressed against its walls by tapping, burnishing, or uniform pressure. Dr. Flagg's method is by tapping. Each successive piece of amalgam is tapped upon by the packing instruments until it combines with its predecessor and is per- fectly adapted to the cavity walls. The set of instruments shown in Fig. 217 are those by which this process is accomplished — Nos. 30-34 being packing instruments, while the others are shapers. 234 PLASTIC FILLING MATERIALS. A convenient and effective set of instruments for accomplishing the packing are shown in Figs. 218-220. I 30 31 32 33 34 35 36 37 38 39 40 Dr. J. Foster Flagg's amalgam and zinc filling instrnments. Dr. W. G. A. Bonwill has advised a method which accomplishes the removal of surplus mercury and the even distribution of the mass, Fig. 218. Fig. 219. Woodson's double-end amalgam instruments during the progress of the filling. Small squares of folded bibulous paper are caught in the jaws of pliers and laid upon the amalgam, when the exertion of pressure by means of amalgam pluggers or pliers forces out the surplus solvent and it is wiped away with the pa])er. The same end is also accomplished by the use of bulbous points of soft rubber. When through either method the cavity is more than half full, the remainder of the amalgam mass is wrung out to express more mercury, and tlie packing is resumed until the cavity is more than full. At the later stages of the filling the process of wafering is usually USE OF AMALGAM. 235 Fig. 221. followed. By means of chamois and heavy pliers (Figs. 221, 222) the amalgam mass remaining is compressed into a wafer, driving the surplus mercury through the pores of the chamois. The amalgam is put in a piece of chamois, and the chamois sack A is entered between the beaks b and C (the latter a roller) ; closing the handles of the instrument progressively squeezes out the mercury till any desired degree of dryness is attained. When the amalgam is squeezed to the requirements of the operator, the han- dles are released, and the spring opens the ap- pliance. The action is analogous to the finger and thumb movement in common use, but is much more powerful, and therefore more cer- tain and more uniform. Small sections of the wafer are laid upon the half-completed filling and tapped into a union with it. The cavity is more than filled, and at the completion of the packing the amalgam should cut as though nearly set. Another and excellent method where applicable is to shape small pieces of half-vulcanized rubber and cement them upon broken excava- FiG. 222. Mercury expresser. Flagg's wafering pliers. tors, and use them as pluggers during the later stages of the filling. The fluid cementing amalgam will have its surplus mercury expressed about the sides of the plugger. Still another method is to fill the cavity more than half full, then cut away the softened portion, and complete the filling with drier amal- gam. Fillings the initial portions of which have been introduced com- paratively dry will be found more homogeneous, less likely to discolor 236 PLASTIC FILLING MATERIALS. and crevice than when more fluid amale-am has been used to begin the filling. An examination of an amalgam filling immediately after com- pletion will show the marginal portions to contain the softer amalgam, the harder being in the more central parts. The too common practice of placing in the prepared cavity sufficient amalgam in one mass to nearly or quite half fill it, is faulty. By no means can this method secure the accuracy of adaptation of filling material to cavity walls which is demanded of a correct filling. At the completion of the packing operation, unless the filling has been finished by wafering, the surface will be found still soft. It has been recommended ' that small pieces of annealed No. 1 gold foil be burnished over the surface of the amalgam, until no more gold can be amalgamated by this means, when the filling will be found quite hard. The indefinite cementing amalgam has combined M'ith the gold, for which mercury has a strong affinity, and formed a distinct amalgam upon the surface of the filling proper. As amalgams of gold are com- paratively soft, it is advisable to first fill the cavity more than full, apply the gold foil, then scrape the filling down to the cavity margins. Dr. Rhein's procedure is to fill the cavity with plastic amalgam and rub on the pieces of gold until no more gold is amalgamated. This gold amal- gam is permitted to remain. The surplus of mercury may also be con- veniently removed by absorbing it from the surface of the filling by pieces of sponge or crystal mat gold. An amalgam filling should be hard enough to resist cutting before the rubber dam is removed. In those situations where the rubber dam cannot be successfully employed, it is the accepted practice to prepare the cavity, sterilize it, when access is difficult sealing a germicide in the cavity for a day ; next adjust a napkin, and having mixed a submarine amalgam (one contain- ing copper and a high percentage of silver), the cavity is dried as well as possible ; a piece of the amalgam is then carried to the deepest recess of the cavity and quickly and forcibly compressed with a mass of bibulous paper. Another piece of amalgam is added and compressed, driving the surplus mercury from the amalgam. While the napkin is in position, a mass of temporary stopping (which see) is softened and placed in the remainder of the cavity. A knife blade passed over the edges of the amalgam will remove overhanging portions. At a subse- quent visit, the rubber dam is adjusted, the temporary stopping is removed, and the filling completed with amalgam. If the ojK'rator prefer, the rubber dam may be adjusted at once and the filling completed atone sitting ; the fi)rmer method is, however, pre- ferable, as the cervical portion of the filling may be perfectly finished, 'Oltolongui's Methuih vj FUlinrj Teeth. "Metliod of M. L. Klieiii." USE OF AMALGAM. 237 and not be in danger of displacement, while the second section is packed. In cavities extending beneath the gum, and opening broadly upon a surface of a tooth where discoloration would be highly objectionable, the cervical half of the filling is made of a submarine amalgam and is completed with an amalgam containing gold, which will retain a better color. Should the external face of the filling be readily visible and not subjected to the stress of mastication, its outer surface is made of a wafer of an amalgam containing zinc, known as a facing amalgam. Copper amalgam is used, when used at all (and that is but seldom), upon the distal and buccal walls of third molars, in cavities extending under the gum line, which are difficult of access and to sterilize, and which cannot be properly dried. A cavity is prepared which need be but slightly undercut. A pellet of the copper amalgam is placed in an iron spoon (Fig. 223) held above Fig. 223. Heating spoon for copper amalgam. a Bunsen flame until globules of mercury appear upon its surface, when it is quickly crushed in a mortar and pounded until made into a paste. There can be no objection to washing the soft mass in aqua ammonia to dissolve and remove oxids which later form discoloring salts, and thus permit a chemical union of the metals which would be prevented by their presence. A napkin, or always when possible the rubber dam, is adjusted, and the filling inserted in sections. At the end of the operation the filling should be firmly compressed with a broad-bladed spatula. In by far the greater number of cases where amalgam was at one time used alone, it is now the accepted practice to place a lining of a zinc cement, and add the amalgam as a resistant and insoluble covering. In cavities which approach the pulp the same precautions are taken for the prevention of thermal shock as with gold. The most difficult class of cases in which to obtain satisfactory results with amalgam are those opening alone upon the approximal surfaces of bicuspids and molars. While it is true that amalgam may be manip- ulated in spaces impossible with gold foil even in soft cylinders, it is essential that sufficient room be obtained for the perfect introduction of the material and its subsequent trimming and polishing ; for polishing is quite as necessary an operation with amalgam as with gold. This 238 PLASTIC FILLING MATERIALS. space is obtained either through wedging or by cutting through the occlusal foce of the tooth into the cavity. Space is to be obtained and amalgam packed in such a manner that the amalgam at the completion of the operation should exhibit no evidence of pastiness. To ensure the removal of the excess of the sol- vent, gold foil may be burnished over it as already described until it requires some effort to cut the mass with a lancet blade. Amalgam when set is more difficult to cut and polish than gold ; the greater por- tion of the carving is therefore done at the same sitting as the fillings l)ut should never be undertaken Avhile the filling is soft. It should be in such a condition that it is necessary to carve, not smear, it into shape. A suitable cutting instrument of the form of Nos. 37 to 40 of Flagg's set (see Fig. 217) is passed first across the cervical border of the filling, removing any excess due to imperfect contact of the matrix with the cervical margin of the cavity ; next the lateral borders are carved, and then the masticating surface. The body of the filling is left full, so that after two days, when the filling receives its final dressing and polishing with cuttlefish disks, strips, pumice, etc., the filling Avill be reduced to correct contour. A polished amalgam filling will retain an untarnished surface when an unpolished one will discolor very objectionably. jNIanv of the cases in which it was at one time the usual prac- tice to fill or restore almost entire tooth crowns with amalgam, Fig. 224. are trimmed down, shaped, and artificial crowns applied. One class of cases is fre- quently seen, in which the indication is for an enormous amalgam filling rather than an artificial crown ; this is, the loss of the dis- tal half of the crown of a molar. As a rule the teeth are pulpless, or it is necessary „ , .. ,, , .,, to devitalize the pulp. The appearance of Rt'sttiration of lower mfilar with i r i r amalgam. the crown after the removal of carious den- tin and cutting away frail enamel walls is seen in Fig. 224. A Herbst matrix is fitted, closely embracing all the margins of the cavity. The rubber dam is adjusted. It is of course understood that the root canals have been properly sterilized and filled. The posterior canal is drilled out for al)Out \ in. and screw-tapped. A thin solution of zinc phosphate is mixed and the tip of a screw to fit the tapped root has its point dipped into the cement, and then quickly .screwed into place. The amalgam is packed in larger masses than usual, using bibulous paper to compress it about the screw and into such scant undercuts as may be secured in the anterior portion of the tooth. The filling is completed with amalgam wafers. USE OF AMALGAM. 239 Such a filling should be well set before the rubber dam is removed. The upper surface is carved into cusps and sulci to occlude properly with the antagonizing teeth. The matrix should remain for twenty- four hours, when it may be split and removed. If the matrix has been exactly adjusted there should be no trimming of the margins required, no carving of contour, and no smoothing, the amalgam being ready for polishing strips. The occlusal surface is smoothed and polished with moosehide points and pumice ; using a stiif brush to polish the sulci. Finishing". — The process of finishing hard amalgam fillings is simi- lar to that of finishing gold. For example : a compound cavity occu- pying the approximal and occlusal faces of a molar. A fine saw is placed in a frame as in Fig. 225, but set to draw-cut with its teeth Fio. 225. The Kaeber saw frame. pointing toward the frame. The blade is passed above the cervical margin of the filling, engaging any projecting amalgam, which is then sawn oif. It is just as essential as with a gold filling that the cervical edge should be exactly flush. The lateral margins of the filling are next carved smooth ; strips of emery cloth are passed into the interdental space and the filling smoothed and rounded, completing this portion of the operation with emery strips of the finest grit. Linen tapes or metal polishing strips are next charged with pumice and passed over the surfaces until they are smooth and the margins are perfect. The occlusal portion is polished by means of rubber or moose- hide points and pumice. Should it be a plain approximal filling, not a " contour," the saw is used to cut away surplus amalgam, and the polishing accomplished by means of disks and powders. Fillings upon the buccal surfaces of teeth are smoothed by means of disks and polished with rubber cups or disks and pumice. 240 PLASTIC FILLING MATERIALS. Gutta-percha . Origin. — The gutta-percha of commerce is the coagulated juice of the Isonandra gutta, a tree of the order of Sapofacecv. The juice is found in all trees of this order, but some specimens are of much higher value than others. That from Borneo is regarded by manufacturers as being inferior ; it is the variety from which the name is derived — ISIalav, gatah or gittah, gum, and jiertja, a tree. The gutta Tuban from Singa- pore is regarded as a superior variety. The mode of securing the juice is by tapping the cambium layer of the tree and catching the juice as it exudes. From this stage to its formation into sheets it undergoes several processes (see works on gutta- percha) ; it is possible that in some of these operations it may have its texture injured by overheating. History. — Gutta-percha was introduced into dental practice as a fill- ing material about the year 1847. Soon after this a secret preparation was introduced by a Dr. Hill, which received his name. Numerous alleged analyses of Hill's stopping have been given, all of which are untrustworthy. It was found to subserve so useful a purpose that it received the tribute of wide imitation ; in fact, the white gutta-percha preparations of the present day had their foundation in this imitation. There is no entirely trustworthy evidence that the original was superior to the best of contemporary preparations. As at present employed as a filling material gutta-percha is in tM'o forms, the first the well-known pink gutta-percha base ])late, which is colored l)y the insoluble sulfid of mercury, the second the white prep- arations, made firmer in texture by additions of the soluble zinc oxid. The specimens of crude gum differ as to the amount of heat required to soften them to an equal degree. Dr. Flagg ^ states that the speci- mens requiring the greatest degrees of heat for softening, prior to the addition of the zinc oxid, afford the best dental gutta-perchas. The method of making the gutta-percha of dentistry is by softening a mass of the brownish-yellow gum on a slab which has been heated over boil- ing water ; and driving zinc oxid into the softened mass by a process of kneading, using a wedge-shaped steel instrument as the kneader. It requires infinite patience and much time to distribute the po\vder evenly throughout the mass. Overheating the material at any stage of its manufacture or manipulation is ruinous to its texture. Classes. — Gutta-perchas are divided into three classes according to the temperature of softening : Loir Jienf, softening below 200° F. 3Ie- dium heat, becomes plastic at 200° to 210° F. High heat, 210° to 218° F. The low-heat specimens contain 1 part by weight of gutta-percha to 4 ' Plastics and Plaxtic Filliny. GUTTA-PERCHA. 241 of zinc oxid ; in medium-heat the ratio is 1 to 6 or 7 ; and in the high- heat specimens the gutta-percha is almost saturated with zinc oxid. Physical Properties. — Gutta-percha is an almost perfect non-con- ductor both of heat and electrictity. It is less hard and rigid than any other filling material. It contracts in hardening, i. e. cooling. Softened masses of it are coherent when dry, but not when wet. Its color may be made to resemble that of the teeth. To vital tissues it is the most bland, unirritating filling material known. After it has served as a filling for a greater or less period it is found to have increased in hardness and difficulty of softening, and its surface, and perhaps its substance, has become porous in variable degree. The increased hardness is observed in such situations as those in which putrefactive decomposition occurs ; that is, in places where there is an evolution of hydrogen sulfid ; the gutta-percha apparently undergoes a species of vulcanization. It becomes somewhat porous in those situa- tions where the formation of a solvent is active (lactic acid), which abstracts the soluble zinc oxid from the mass. The pink variety con- taining the insoluble mercury sulfid does not become porous, but wears with a comparatively smooth surface when subjected to attrition. Examining in detail these several physical properties it will be noted that gutta-percha has but one property in common with gold — its insol- ubility. Its rational employment is therefore in such situations and conditions as those in which the use of gold is contraindicated. Indications for its Employment. — First, in its several forms it is employed as a temporary filling material for both the temporary and permanent teeth. Owing to its non-conductivity it is employed near the pulp ; its insolubility recommends its use at the cervical margins of cavities, particularly in the buccal cavities of molars which do not extend to the masticating surface, where the non-resistance of the material would cause its rapid wasting. This is the most common of the situations in which gutta-percha is applied : very deep cavities upon the buccal surfaces of molars, extend- ing beneath the gum, and having ragged enamel margins, the orifice of the cavity being much smaller than its body. Owing to its non- irritating quality, the condition of the gum in contact with a gutta- percha filling remains normal. It is used in approximal cavities of the anterior teeth which have a similar form to those just described ; also in labial cavities, particularly when these teeth are in any degree loose. For example : in a cavity opening alone upon the distal wall of a cuspid tooth the carious process has almost invaded the pulp, the enamel walls unsupported by dentin still retain their form and have a good texture. Pink base plate is invaluable for the temporary filling of spaces after 16 242 PLASTIC FILLING MATERIALS. wedging and also the cavities to be subsequently filled with metal. A mass of the material may be packed into such spaces and be permitted to remain for months if desired, the gum in contact with it after its prolonged presence exhibiting no indications of irritation. Masses of gutta-percha may be packed in interdental spaces where there is not sufficient space for the introduction of contour fillings ; with the pur- pose of having the teeth gradually separated by the impact of mastica- tion, the gutta-percha acts as a persistent and very gradual wedge. When it has been determined that an excavated cavity is unfit for the reception of a permanent filling, gutta-percha is the filling material par excellence. Although it is stated that gutta-percha shrinks markedly in harden- FiG. 226. Flagg's gutta-percha softener and tool-heater. ing, cavities in which it has been properly placed exhibit no evidences of softening after tlie material has been worn for months, or it may be G UTTA-PERCHA. 243 for years. Particularly is this true when the pink variety has been employed and the method of introduction is correct. Fig. 227. Mode of Softening. — Gutta-percha should never be heated beyond a point which permits of accurate adaptation to undercuts and frail walls. The soften- ing should be gradual. Any heat in excess of this is not only harmful but ruinous. For its proper softening some device is necessary which shall permit of this type and degree of heating (see Figs. 226-228, 237). Fig. 226 illustrates the heater of Dr. Flagg. There are three metallic shelves, the highest of which receives the least amount of heat, and is designed for softening low-heat gutta-percha. The second shelf is for the softening of high-heat specimens. The lowest shelf and rack support the packing instruments, which are kept at a higher temperature than the filling material. Fig. 227 illustrates a device of Dr. L. A. Faught for the packing of gutta-percha. The heating wires connect at the bases of the instrument points, which are of aluminum, and sufficient heat is conveyed to the gutta-percha to maintain it in a plastic state during the packing operation. Instruments. — As a rule the instruments used in packing gutta-percha are too large and the material itself is used in too large pieces. If the cavity is of considerable extent, and usually it is, the filling should be introduced in four or more pieces. It is preferable to warm all the packing instruments so that the gutta- percha will remain plastic until perfectly ada]3ted. Manipulation. — The rubber dam having been ad- justed, the cavity excavated and sterilized, the frail enamel edges broken away, without any particular object of margin form- ing, but to gain space, the cavity is dried for the reception of the gutta- percha. The field of operation should be dry, in order that each additional piece of gutta-percha shall adhere to its predecessor, which it would not do if wet. A softened pellet is taken upon the point of a probe and placed in the most inaccessible portion of the cavity and tapped into accurate contact with the tooth walls (by Order of placing gutta-percha peUets. Dr. Faught's electric heater. 244 PLASTIC FILLING MATERIALS. means of the corkscrew plugger No. 32 or No. 33), as shown in No, 1 of Fig. 228. A second pellet is added (No. 2) and similarly manipulated. The Nos. 3, 4 pellets are packed in the order shown in the figure. In adding the last piece broad-faced instruments are used, adapting the gutta-percha accurately to the margins of the cavity. The softened gutta-percha may be made to adhere better to the walls of the cavitv if these be first coated with one of the lining varnishes. Another method of manipulation is to line the walls of the cavity with pellets until a cylindrical cavity remains. A cylinder of gutta- percha of that size is nearly softened and pressed firmly into the cavity by means of a broad spatula. Should the cavity be very deep, the pulp almost exposed, the por- tion of dentin overlying the pulp is to be covered by a thin pellet of low- heat gutta-percha softened sufficiently to permit of adaptation. A disk of pink gutta-percha ))ase plate answers admiral>ly for this purpose. Dr. How's Improved Gutta-percha Fillings. — Dr. W. Storer How ^ has published a method of packing gutta-percha which is as excellent as rational, when the directions given are closely followed : "Many approximal cavities like C, Figs. 229, 230, may well be Fig. 229. Fig. 230. Fig. 231. m /Bl U —A mL Approximal cavities. filled with gutta-percha, and such as C, Fig. 230, where a gold filling would slioAV through the thin enamel front, can better be filled Avith suitable gutta-percha. The section, Fig. 231, shows the angles .^, .4', Avhich should be given the enamel-edges when practicable, and in any case the enamel-margin should have a squarely defined angle at its surface border. Fig. 232. Fig. 233. Fig. 234. Fig. 23o. Fig. 236. Cervieo-labial and buccal cavities " Cervico-labial or buccal cavities, as shown in Figs. 232 to 236, admit of permanent gutta-percha fillings. Of course due attention ^ Dental Cosmos, vol. xxxiv. p. 281. GUTTA-PERCHA. 245 must be given to the retention of the fillings by enlarging the interior walls of the cavities when they have not already such expansions. After suitably preparing the cavity, it should be made as dry as possible and so kept. The problem of conveniently and properly softening pellets of gutta-percha has been solved by the production of the ther- moscopic heater shown in Fig. 237, which approximates the exact size Fig. 237. r^ Thermoscoplc heater for gutta-percha. of the device. The heater is in this instance made of steatite, because of its heat-retaining property and the desirable physical qualities of its surface. The handle is of wood, at the opposite end from which, in the centre of the circular recess, is a small disk {A) of metal, fusible at about 112° F. On the heater near the metal a suitable number of gutta-percha pellets, as 1, 1, are placed, and the heater held over the flame of the annealing lamp or burner (as in the illustration) until the fusible metal melts, when the heater is placed on a piece of cardboard (or an empty foil-book), and the gutta-percha will be found to be prop- erly softened. The steatite plaque retains the heat long enough for an ordinary operation, but if the metal meantime loses its fluidity and so indicates a lowering of the standard heat, it may be quickly restored by a moment's holding of the heater over the flame, which will again fuse the metal. " When the flame is a]>plied directly under the metal, as in the illus- tration, the material placed at 1 will, when the metal is seen to be fused, be at the heat of near 208° F., while the pellets at 2 will be heated to about 200°, those at 3 and 4 to near 194° and 180° respectively. Of course the location of the heat-source will produce corresponding varia- tions in the relative temperatures of the materials as severally situated ; 246 PLASTIC FILLING MATERIALS. but with a visibly definite standard such as the metal A, having a known fusing point, the desired degree of lieat may repeatedly be produced at any place on the receiving surface of the heater. A few seconds' contin- uance of the heater over the flame, after the metal has melted, will raise the surface heat to 212° or 215°, as the case may be ; but as a suitable indicator for a high-heat stopping, a button {B) of metal fusing at 230° is provided as a substitute for A, which is first melted and poured out on a piece of clean paper, the heater cavity being undercut so that when cold the metal cannot be shaken out. The boiling of a few drops of Waaler in the heater cavity will likewise serve to indicate the proper temperature, but the fusible metal is in every way preferable. The preferable procedure is to hold the heater over the flame until the Pj ^gg metal melts, set down the heater, blow hot air into the previously prepared and dry cavity until the tootli is sensibly warm, hold the heater again over the flame to melt the metal, and then with a suitable broad and cold instrument pick from the heater a pellet or group of pellets sufficient to a little more than fill the cavity, and by a quick, firm, rock- Trimming margins of iug pressure force the mass into the cavitv as if it gutta-percha liUing. ^^.^^.^ ^^^^^j^^ ^^ ^^^j,^ ^^_^ impression of the same. Then dip the instrument into ice-water, wipe dry, and hold it firmly against the filling for one or more minutes, after which witli a keen- edged thin blade pare oif the surplus, cutting from the centre ol)liquely toAvard the margin, as in Fig. 238, taking great care that the filling B shall be flush with the cavity margin at every point, as at A, A', Figs. 239 and 240. " Access to approximal cavities, as C, C, Figs. 229 and 230, will seldom permit the instantaneous mass-method just described, but in many such cases a warm, broad, flat blade, as stiff as the space will admit, can by repeated quick pressures be made to squeeze the soft mass into the cavity of the warmed tooth, and be instantly followed by a very thin strip of metal held tightly in both hands and wrapped with hard pressure over the filling around that side of the tooth, to l)oth condense and contour the plastic and produce the closest adaptation of the material to all parts of the cavity walls. " There is good reason for the belief that tlie common mode of suc- cessively introducing small })ieces of imperfectly softened gutta-percha into a com})aratively cold cavity, and employing instrument points more or less heated for packing the cooled j)lastic against one side of the cavity after the other, must in the nature of the case result in a leaky filling, such as gutta-percha is commonly said to make, whereas the defect is due not to the material, but to its inconsiderate manipulator. GUTTA-PERCHA. 247 " In order to definitely determine whether or not suitably softened gutta-percha inserted by the mass-method will make a moisture-tight filling, some porcelain teeth of natural sizes and forms were made, hav- FiG. 240. A'- FiG. 244. A' A'- n ing cut in them, prior to baking, cavities of the class shown in Figs. 229 to 236. These cavities have been filled with gutta-percha, leaving a surplus over the margins as at a, a,' Fig. 241, and when quite cool paring them flush as at A, A', Figs. 239 and 240, and after several days' immersion in dilute aniline ink, the fillings have been removed without a trace of color showing on the walls of either the fillings or the cavi- ties. The only exceptions have been where the margins were rounded, as at a, a', Fig. 241, and the fillings not cut below them as shown, but left feather-edged as at d, d', Fig. 243. In these few instances discolor- ations were found under the laps, but in no case extending farther than to A ', A ' , Fig. 244. The tests prove that under conditions as nearly practically parallel as extra-oral tests can well be, gutta-percha fillings properly made will exclude external moisture. Obviously, it is better to pare the filling below the enamel-slopes, as in Figs. 242 and 244, than to leave it overlapping, as in Figs. 241 and 243. For a final finish use a rapidly revolved, lightly-touching cuttlefish-paper disk, followed by a wisp of bibulous paper or piece of tape wet with chloro-percha, applied for but an instant, to glaze the surface of the filling, " In the case of a very thin enamel front like that of Fig. 230, that part of the cavity C may be varnished with thin chloro-percha and dried with hot air just prior to filling it as before said. It might first be thinly coated with a tinted oxyphosphate or oxychlorid of zinc, Avhich should be given ample time to harden before placing the gutta-percha. Indeed, it is a fundamental feature of good gutta-percha work that while one cannot operate too rapidly when the plastic is at its proper temperature, the preparatory and completing processes should be given as much time, care, and close scrutiny as more elaborate and often less enduring gold operations. There is furthermore room for the exercise of the artistic faculty in having at hand chloro-percha, or cellulose varnish of varied colors, with which, by means of a small 248 PLASTIC FILLING MATERIALS. brush, a gutta-percha filling as B, Fig. 232, and one in the like cavity C, may be given an inconspicuous ^hade, and the painting be rencAved from time to time, if that be necessarv bv reason of wear. Fie:. 245 is a sectional view of fillings like B, C, Fig. 232." Finishing Gutta-percha Pilling-s. — If a gutta-percha filling has been packed with the proper amount of care and skill, it should require but little trimming. It should be undisturbed until cold. Its harden- ing may be hastened and intensified by holding ice-water in contact with it for a few moments. The portions overlying the margins are to be trimmed with extremely sharp lancets or by warm blades. Every cut should remove a little of the surplus material, never a mass of it, and should be made toward the cavity margins, never away from them. The filling should have been made so that no fulness is present to require reducing. It is a general practice to give a smooth face to a gutta-})ercha filling by wiping it with a tape which has been slightly moistened, not wet, with chloroform. The surface produced by this means, although smooth, does not retain its integrity so well as when the surface is formed by cutting. The use of gutta-percha as a canal filling is discussed in Chapter XYII. Basic Zinc Cements. Zinc Oxychlorid. — The basic zinc cements employed in dentistry are the oxychlorid and the phosphate, the oxysulfate should also be included. The oxychlorid is formed by the combination of calcined and pul- verized zinc oxid with a solution of zinc chlorid : ZnO + ZnCL + H.O = 2ZnClHO. This compound was introduced as a dental filling material about 1850, its hardness, whiteness, and apparent insolubility recommending it for that purj)ose. It required no lengthy ])eriod of time to demonstrate that as a filling material per se it was unfit for use. It disintegrated ra])idly and was not free from shrinkage, Pkoi'ERTIes, — Freshly mixed, this material is irritating to vital tissues with which it is brought in contact ; ai)plied close to or upon an exposed pulp it may l)e productive of a transient or a persistent irrita- tion, or even inflammation. The extent of the irritation is largely governed by the fluidity of the cement paste, /, e. the amount of zinc chlorid present. It sets in fifteen minutes sufficiently to permit the packing upon it BASIC ZINC CEMENTS. 249 of an amalgam, and in half an hour a gold filling. After setting it is whiter though less hard than the zinc phosphate ; it shrinks, particularly when used in large masses. It is a poor thermal conductor, and, like all bodies containing zinc oxid, is soluble in lactic acid — the usual sol- vent in the oral cavity. These several features are at present regarded as limiting the application of oxychlorid to — first, a lining material for carious cavities over which the insoluble filling proper is to be placed ; second, as a root-filling material (its use in this connection is discussed in Chapter XVII.). It is to be noted that the cement retains after setting an antiseptic power for a greater or less period. Use. — Zinc oxychlorid is usually employed as a lining material in teeth having what is known as poor structure — those in which caries proceeds to great depths without external evidence of the extent of invasion. After these cavities have been partially excavated it is found that further excavation and the removal of the deepest layers of the leathery dentin which appear to have retained sensitivity would prob- ably uncover the pulp ; it may be that the pulp has given subjective evidence of a mild attack of active hyperemia. In such cases the deepest layer of the partially disorganized dentin is permitted to remain and is subjected to the prolonged — fifteen minutes or longer — contact of hydrogen peroxid in the 25 per cent, ethereal solution (caustic pyrozone), or preferably a saturated solution of thymol in alcohol. The cavity walls are well dried with bibulous paper and the warm air blast. Upon a mixing slab (see Fig. 246), a drop or two of the zinc chlorid is placed, and beside it a quantity of the zinc oxid powder. The powder is gradually incorporated with the fluid by means of a spatula until a creamy paste is made. A number of balls of bibu- lous paper are to be at hand. A portion of the paste is taken upon the end of an instrument and placed in the cavity, where it is quickly pressed into a layer against the cavity walls by means of the balls of bibulous paper. The walls are to be covered to a uniform depth of about one-sixteenth of an inch in thickness. The prompt application of the bibulous paper usually prevents any irritation due to the contact of the oxychlorid with the dentin overlying the pulp. Should the cavity be very deep it is advisable to protect the pulp by interposing a film of ethereal varnish between the oxychlorid and the dentin over the pulp. At the completion of the lining operation, the margins of the cavities are to be cleansed of the oxychlorid and the filling completed with the material indicated. Zinc oxychlorid as an obtunding agent in the treatment of hyper- sensitive dentin is of considerable value, and its use for that purpose is described in Chapter Y., p. 129. 250 PLASTIC FILLING MATERIALS. The use of zinc oxychlorid as a canal filling, and the mode of using it, are discussed in Chapter XVII. The powder of this cement is made of zinc oxid calcined and pow- dered ; to which have been added substances (borax, silica, etc.) which affect its properties but little if at all. The fluid is made by dissolving pure zinc or its oxid in hydrochloric acid to the point of saturation ; or, by making a solution of zinc chlorid 4 parts, Avater 3 parts, and filtering the solution. The use and effects of zinc oxychlorid as a jiulp capping are dis- cussed in Chapter XIV. Zinc Phosphate. — These cements are nominally a combination of calcined zinc oxid with a syrupy solution of orthophosphoric acid : 3ZnO + 2H3PO, = Zn3(PO,), + SH.O, although their actual composition is more variable than that of any other filling material. Both base and solvent commonly contain impurities — those of the base owing to lack of discrimination, or worse, in the source of the oxid. Many of the impurities of the phosphoric acid are due primarily to the well-known inconstancy of the acid itself, and others to the mode of its manufacture. Many of the specimens of powder are prepared from commercial metallic zinc, and therefore contain the impurities of that metal. Among the latter is arsenic, so that the presence of arsenic compounds in inferior cement powders is by no means impossible, which no doubt explains in many cases the death of non-exposed pulps in teeth which have been filled with zinc jjhosphate. A common source of the glacial phosphoric (metaphosphoric) acid of commerce is from sodium phosphate, variable quantities of which are retained in the acid solution as acid sodium phosphate (dihydrogeu sodium phosphate). This substance is soluble in water, and must there- fore greatly increase the solubility of any cement containing it. To properly make pure specimens of zinc oxid and phosphoric acid are comparatively expensive operations, which will serve to explain the seemingly high cost of fine specimens of cement, and incidentally serve as a warning against the indiscriminate use of cheap cements. Making of Poavder. — A quantity of pure zinc oxid is luted in a sand crucible and kept at the highest forge-heat for hours. AMien cool the crucible is broken away and the vitreous mass of yellowish zinc oxid is reduced to a powder which will pass through a fine bolting cloth. This powder is placed in tightly stop])ered bottles, for if exposed to the air it absorbs carbon dioxid and a portion of it is converted into the hydrated carbonate of zinc. This change may be noted in old powders, BASIC ZINC CEMENTS. 251 by the effervescence due to the disengagement of carbonic oxid when phosphoric acid is added to them. Numerous substances have been added to the basal powder with the object of lessening the disintegra- tion, /. e. chemical solution, when used as a dental cement. Usually these additions are the oxids of other metals. The oxid of magnesium added to the powders causes the cement to set more rapidly ; the oxid of aluminum increases the rapidity of setting and makes a finer-grained cement, the central texture of which is, however, inferior. Cements of zinc oxid and phosphoric acid alone are apparently less soluble in lactic acid than when the oxids of aluminum and magnesium are added. Various other substances have been added which do not enter into chemical combination with the phosphoric acid, in the hope of confer- ring greater durability on the cement, but as yet but few of them have been shown to possess any value. The Fluid. — Phosphoric acid in its pure state is formed by hydrating phosphorus pentoxid : PA + 3H20 = 2H3PO,. Much of the phosphoric acid used for cements is made by hydrating the glacial (metaphosphoric) acid, HPO3. The acid dissolves readily in water, being even deliquescent when pure. Difficulty of solution is therefore an indication of impurity af the glacial acid. It requires a definite degree of heat to bring about the chemical hydration of the acid. At a temperature of 210° F. the union occurs, which is attended by the evolution of heat, the glacial acid being transformed into ortho- phosphoric acid. These acids are all hygroscopic. They will even ab- stract water from sulfuric acid. Impurities. — The commercial glacial acid is commonly, or as a rule, impure, containing variable amounts of sodium and magnesium phos- phates. These salts, particularly the dihydrogen (acid) sodium phos- phate, are permanently soluble in the phosphoric acid, and therefore give no evidence of their presence by the formation of precipitates. They are also soluble in water, which fact has a direct bearing upon the durability of cements made with the impure acid. It has been stated by writers that the acids of cement were occasion- ally the meta- and pyrophosphoric. A test of some of them said to be of these varieties, showed none of them to give the reaction of the pyro- acid ; a few giving traces of the meta- acid. Precipitates which form in cement fluids are probably metallic phos- phates. The instability of cement fluids is notorious. Aside from the known or probable contaminations which they may contain this insta- bility is to be regarded as a distinctive feature of phosphoric acid. 252 PLASTIC FILLING MATERIALS. The Cement. — To make the cement, successive portions of the oxid are mechanically incorporated with the fluid until a stiff paste results. In five minutes a ball made of the paste glazes, and reboftnds when dropped upon a hard surface. It breaks with a granular surface ; in fifteen minutes it is cut with some difficulty. If the cement fluid con- tain the acid sodium phosphate, an acid reaction may remain for hours or davs. The atmospheric conditions markedly modify the properties. In warm, or hot and moist weather, the setting is more rapid and it may be sudden. In cold weather it is delayed. The greater the dilu- tion (the thinner the fluid), the more rapid the setting. In its freshly mixed state zinc phosphate is adhesive, losing this property in a great degree when set, if surrounded by moisture. It has a higher rate of heat conductivity than zinc oxychlorid. Uses. — Its legitimate field of usefulness is in situations and under conditions where its advantageous properties may be utilized, and its disadvantages minimized. One of the principal facts to be borne in mind is the solubility of the cement in lactic acid, which is present almost always about the necks of the teeth, in approximal spaces, and along gingival margins. Its clinical use is therefore attended by the greatest measure of success when placed at a distance from such situa- tions — as, for example, in cavities opening upon the masticating sur- faces of teeth, where its great hardness is an element of advantage. Good specimens have been known to last for periods varying from three to eight vears. Dr. Henry Weston has cited cases where an un- usually good zinc phosphate filling has lasted for ten years. As a filling material per se, zinc phosphate has but limited employ- ment except for the teeth of children, and as a temporary filling in the teeth of adults. Times and occasions will suggest themselves to every operator M-^here gold, amalgam, and gutta-percha are contraindicated as filling materials ; in such cases zinc phosphate performs a useful ser- vice. Its great field of usefulness — where, indeed, there is no substi- tute for it — is in the filling of the greater portion of extensive cavities, which are then filled and sealed with gold or amalgam by an inlay, or it may be by a partial crown. It is invaluable, and in most cases indispen- sable, as the retaining medium of fixed bridge work and of many forms of artificial crowns. Prior to placing the zinc phosphate filling in a cavity, it is a wise precaution to line the cavity with one of the quick-drying ethereal var- nishes, to protect the dentinal walls from contact with acid sodium phosphate which may be present in the cement. In some cases the placing of the cement in proximity to a non-exposed pulj) is productive of marked suffering. Should the cavity be very deep it is the usual practice to place a softened disk of gutta-])ercha over the wall nearest BASIC ZINC CEMENTS. 253 Fig. 247. Fig. 249. m Fig. 246. Fig. 248. the pulp. The rubber dam should always be adjusted before the inser- tion of a phosphate filling, to ensure dryness not only during the inser- tion but during the period of hardening, at least fifteen minutes. Mixing of Cement. — This is an operation of equal or greater im- portance than any other in the manipulation of zinc phosphate. Dr. Henry Weston has demonstrated how, almost entirely, the mixing of cement governs its stability. Specimens of the same powder and fluid mixed after dif- ferent methods gave entirely different results, not only in the appearance but also in the hardness, texture, and solu- bility. The method of mixing set forth is that of the same experimenter. As- suming for illustration that an approx- imal cavity is to receive a contour filling, or a large occlusal cavity is to be filled, or an extensive cavity is to be three- fourths filled by cement : A drop, or, where a large mass of cement is required, two drops of fluid are placed upon a scrupulously clean glass (Fig. 246) by means of the drop- Glass mixing tablet, with rubber feet. per shown in Fig. 247, and a mass of powder, in great apparent excess of that required, is heaped at a distance from it, taken from the bottle by the scoop (Fig. 248). A portion of the powder is drawn into the fluid by means of a stout spatula (Fig. 249), and stirred with a rotary movement until a thin paste is made ; another portion of powder is then added and is slowly and thoroughly incor- Seoop. Spatula. 254 PLASTIC FILLING MATERIALS. porated ; more powder is added until the mass is as thick as putty and difficult to smear with the heavy spatula ; the mass is scraped together, taken from the spatula, and rolled between the forefinger and thumb, which have been well scrubbed. The mass is now kneaded, then rolled into an oblong pellet. If for an occlusal cavity a piece about one-fourth the size of the cavity is set in the deepest portion and tapped into perfect apposition with the cavity walls by means of a burnisher. Other pellets are added, and the process is repeated until the cavity is exactly full, the burnisher form- ing the surface of the filling and outlining clearly every margin of the cavity. The filling should remain under rubber dam for at least fifteen minutes — longer when possible. A coating of ethereal varnish, a solu- tion of gutta-percha in chloroform, or melted paraffin, as suggested by Dr. Bonwill, is applied to the surface and the grinding of the filling deferred for a day or two. Should the cavity be upon an approximal side of a tooth, a matrix is to be employed ; the most satisfactory and quickly adapted instrument for this purpose is one of the composition silver strips used for carrying polishing powders (Fig. 250). A strip Fig. 250. Polishing strip. as wide as the length of the tooth is to have one end rolled upon itself until it forms a cylinder more than one-sixteenth of an inch thick (Fig. 251, .1). The strip is passed into the next interdental space and drawn Fig. 251. through until the cylinder {A) rests firmly upon the teeth; the free end is now passed through the space into which the cavity opens ; where it rests upon the lingual surface of the tooth it is burnished into contact with the edges of the cavity, forming walls to the latter (251, B). The cement is introduced as in the preceding case, and when the cavity is full, the free end of the strip is drawn upon, compressing and round- ing the filling. Should the cement be an adhesive specimen or mixed TEMPORARY STOPPING. 255 thinner than described, the surface of the flexible mat- Fig. 252. rix is to be faintly oiled by means of olive oil. At the completion of the operation the cement should be exactly flush with the margins except at the labial aspect, and the surface of the cement should have such smoothness that polishing is not necessary. Cement fillings are polished dry with the finest of cuttlefish disks. The process of filling the body of any cavity is the same, except when the enamel walls are thin and frail. In the latter case, where space permits, it is preferable to line the walls with the oxychlorid of zinc over which the phosphate is placed. Before inserting a veneer fill- ing of gold or amalgam, each cavity margin must be scraped free from cement. When orthodontic appliances such as rings or caps, or prosthetic appliances, crowns and bridges, are to be set it is preferable to use a cement prepared for that purpose, although it is the general practice to use the cement to which the operator is accustomed, mixing it thinner than for filling purposes. Wherever possible, it is advisable to operate under rubber dam, even while setting orthodontia appliances. The tooth is cleansed with chloroform — as, for ex- ample, when a ring or cap is set^ — to remove fatty mat- ters, and a layer of shellac varnish applied, which is then dried by the air blast (chip blower). Cement paste is formed, of such consistence that it will flow readily and yet not be watery ; the inside of the band or cap is filled with cement by means of an appropriate spatula (Fig. 252) ; a layer of cement is placed on the tooth where it is to be embraced by the band, which is then pressed into position and is to remain without disturbance until it is hard. The application of bands or ligatures should be deferred until the following day. As soon as the cement is hard the surplus is cut away and the dam removed. Pointed spatula. Temporary Stopping. Preparations of this name are compounds of gutta-percha with various substances added to lessen the temperature of softening. As procured from the manufacturer they are of two varieties, the adhesive and the non-adhesive — or, to be more precise, the less adhesive^ 256 PLASTIC FILLING MATERIALS. The former preparations, the adhesive, are usually made of gutta-percha (generally the pink base plate), Burgundy pitch, white wax, and chalk or zinc oxid. In the non-adhesive varieties the Burgundy pitch is omitted. The latter varieties are usually made of a pink color, to furnish a safe- guard against mistaking a filling of temporary stopping for one of gutta- percha. As the name implies, they are designed for temporary use, retaining dressings in teeth, to maintain space between teeth which have been wedged apart, until the attendant pericementitis subsides ; to press away gum tissue overhanging the margins of a cavity ; to fill excavated cav- ities for a few days. Unlike gutta-percha, most of these preparations cannot l)e permitted to remain for a prolonged period ; they usually become oifensive, par- ticularly so when the hygiene of the mouth does not receive proper attention. To maintain space and press away gum tissue they are used as gutta-percha ; their lower heat of softening permits their application close to the pulj) of a tootli without the painful response associated with placing hot gutta-percha in the same })osition. A prominent use of the material is the sealing of arsenical applications in teeth. As with any other material, it is necessary, in order to have the minimum of pain, to make the application and mani})ulate the stopping so that no pressure shall be exerted upon the pulp. Temporary stop- ping is inferior to zinc phosphate for this purjione, as the latter may be flowed into a cavity and over an arsenical application without causing the slightest pressure. Should the cavity of decay extend to or beyond the gum, a small conical piece of the temporary stopping should be softened and packed carefully against the cervical margin and gum, to act as a guard to the latter against contact with the virulent irritant arsenic trioxid. The arsenical paste on a minute pledget of cotton is laid upon the exposed pulp — if the latter be hypersensitive, beside it — and the remainder of the cavity and interdental space are filled with one very soft piece of temporary stopjiing. Temjiorary stopjjing, in cones, has been used as a canal filling (see Cliapter XA^II.) and as a filling for the bulbous portion of pulp chambers. Another im])ortant use of the material is the sealing of the occlusal cavities of teeth which are under treatment for septic pericementitis. Plugs of softened temporary stopping have been nsed for the arrest of alveolar hemorrhage ; also for the temporary setting of artificial crowns. LINING VARNISHES— OXYSULFATE OF ZINC. 257 Lining Varnishes. These are solutions of various gums and resins in alcohol, chloro- form, and ether, which are employed to furnish a non-conducting and impermeable film to cover the dentinal walls of excavated cavities. The first, sandarac varnish, is a thin solution of saudarac in alcohol. The second, a solution of virgin rubber in chloroform. The third a solution of hard Canada balsam, copal, or dammar in ether. Another is the preparation known as kristaline, a solution of trinitro- cellulose in methyl alcohol. Before lining a cavity with zinc oxychlorid, a film of one of these varnishes, the quick-drying ones preferred, is applied, and when this is dry the cement may be inserted without causing pain. A'^arnishes have been used to furnish an adhesive surface upon which to pack gutta- percha fillings. It is always advisable to varnish the walls of a cavity which is to receive a filling of zinc phosphate, to prevent the action of any free acid or acid salt upon the dentinal walls. Some of these varnishes are admirable non-conductors, and serve in that capacity under gold or amalgam fillings in a most satisfactory manner. They may be used to prevent the tooth discoloration due to the pres- ence of amalgam, particularly of copper amalgam. OxYSULFATE OF ZiNC. What is known as the oxysulfate of zinc, in dental parlance is merely a thin zinc oxychlorid, containing zinc sulfate. A true zinc oxysulfate is made by mixing a saturated solution of zinc sulfate with uncalcined zinc oxid. It forms a white paste which sets quickly and attains about the hardness of an inferior plaster-of-Paris. It is bland and unirritating to exposed pulps ; is a non-conductor ; is faintly and persistently astringent.^ Its principal use is as a pulp capping or protective. A thin paste is made, in which a disk of paper is dipped, then quickly and accurately laid upon the area of exposure. When hard (in a few seconds) a drop of fresh thin paste is flowed over the capping. The cavity may then be lined with zinc phosphate. As a pulp protector from thermal shock it is applied in a thin layer, and over it a lining of zinc phosphate is packed. ^ J. Foster Flagg. 17 CHAPTER XI I. COMBINATION 1 FILLINGS. By Dwight M. Clapp, D. M. D. The use of more than one material for filling a single cavity was suggested by the observation of the condition of fillings composed of but one material and noting the effects of time and use thereon. If a large number of amalgam fillings in crown cavities are exam- ined, many will be found to have imperfect edges. One cause of this imperfection is, undoubtedly, the brittle character of amalgam, in con- sequence of which the edges have become broken. In other words, amalgam as a filling material lacks edge strength. Its dark, sometimes almost black, color also renders it very objectionable, especially if used in conspicuous positions. If the same number of gold fillings in occlusal cavities are examined, the edses will be found in better condition than was the case with the amalgam. One reason for this is, undoubtedly, because gold is not brittle, but possesses sufficient edge strength to withstand the force of mastication. Its color is also less unsightly than that of amalgam. For occlusal cavities, therefore, gold is regarded as the better filling material. If a series of occluso-approximal cavities filled with gold be studied, it will be found that the teeth are in much better condition on the oc- clusal surface than at the cervical borders of the fillings. Compare gold fillings with a series of amalgam fillings in the same class of cavities, and the condition of the teeth will be reversed : at least a much larger percentage of the teeth will be found in good condition around the ap- proximal portion of the fillings than was the case with the gold. Hence, the deduction is inevitable that, of these two materials, amalgam is the better to fill the cervk-ul portion of approximal cavities. ^ The term "combination " is adopted for the various fillings here described, in which more than one material is used, V)ecause it seems to be the most comprehensive. The putting together of different materials in filling teeth makes in no sense a chemical combi- nation, in which "any part of the compound is the same as any other part of it." Strictly speaking, the fillings are more "mixtures" than "combinations." According to the best autiiorities, however, the meaning given to combination makes its use here quite admissible. 258 Z/JVC PHOSPHATE AND AMALGAM. 259 Zinc phosphate cement has many admirable qualities and is one of the most valuable filling materials known. It is easily worked, its color is good, its adhesiveness serves to bind tooth and filling together as the stonemason's cement unites the blocks of granite that he piles one on the other into one solid piece of masonry. As a tooth-saver it has no equal ; but its one great defect, its solubility in the fluids of the mouth, restricts, in a great degree, its usefulness when exposed to these fluids. From this it will be easily understood why it is often desiraVjle to combine in one filling two or more diiferent materials ; and it may be said with truth that the operator who selects his filling materials with the best judgment, and combines and uses them with the most skill, will save the greatest number of teeth. There would be just as much common sense and scientific reason for an electrician to make a dynamo entirely of copper, or a watchmaker to use nothing but gold in making a watch, as for a dentist to fill many of the cavities that come to him with but one material. It is an error to think that combination fillings are resorted to because more easily made than fillings of but one material, or, that it indicates a lack of skill on the part of the operator who makes and recommends them. On the contrary, it is often much more difficult to make a suitable combination filling than one of any single material ; and the student will find that combination work will give ample opportunity for the employment of all the skill and ingenuity he may possess. Every operation must be made with the greatest amcjunt of care and attention to minute details, or the object sought will be unattained, and the result be an inferior piece of work which will sooner or later cause grief to the patient and chagrin to the operator. It is impossible to describe all the combination fillings that have been found advantageous and useful, therefore only some of the most important will be considered in detail. The list is limited only by the perverse manner in which teeth decay, and by the ingenuity of the ope- rator to devise scientific and practical combinations to meet the cases presenting. It is to be understood in every instance in this chapter that the teeth are in proper condition to be filled without further treatment. If pulp- less, the roots are supposed to have been put in a healthy condition and filled. In cases of exposed, or nearly exposed, pulps, they are supposed to have been properly protected, and the teeth ready in every respect for the mechanical operation of inserting the fillings. Zinc Phosphate and Amalgam. In Simple Cavities. — This combination is of the greatest service in saving badly decayed teeth, that otherwise might have to be cut off and 260 COMBIXA TION FILLINGS. Fig. 253. crowned, or, perhaps, lost altogether. The simplest cases where it may judiciously be employed are occlusal cavities. Many such cases are seen where there is little left but the enamel, which, however, is thick around the orifice of the cavity, and, if properly supported, will have sufficient strength to withstand the ordinary strain of mastication. Great care should be taken to remove the decay from every i>art of the cavity, being sure that none is left under the cusps or any i)art of the overhanging enamel. The edges of the cavity must be carefully trimmed, so that the filling can be finished flush with the external surface, in order not to leave any overhanging portion of amalgam to be l^roken off, as it certainly will be if so left, to the great injury of the filling. There are but few cases, even in occlusal cavities, where the rul)ber dam should not be used, at least for the final excava- tion and for putting in the filling; for it is almost im- possible to l)e sure that all decay has l)een removed from a cavity unless it is dry. No filliug should be allowed to get wet before it is all in place if it can possibly be avoided. It is much better to err by using the rubber dam too often than not often enough. Fig. 253 shows a cavity such as described. The cavity being ready, sufficient amalgam to fill one-third of it is prepared. Before introducing the amalgam, however, the cavity is filled two-thirds or three-fourths with rather soft cement, into which pieces of the prepared amalgam are crowded, forcing the cement into every })ortion of the cavity. The cement which has oozed out around the edges is then removed with an excavator, and the operation will liave the ap- pearance shown in Fig. 254. The filling is then com- pleted in the same manner as an ordinary filling of amalgam in an occlusal cavity. The advantages of this kind of filling are many : The bulk of it is of cement, which does not change its shape jierccptibly, and is the best of materials when not ex- ])osed to the fluids of the mouth. The cement firmly unites the tootli to tlie filling, thus making a support to the frail walls as well as a sto))})ing to the cavity. The amount of metal is reduced to just enough for a covering of sufficient strength to guard the cement, and the tooth will not be discolored by the amalgam, as is often the case in teeth of not very dense structure, and especially in the mouths of young patients, when not thus ]>rotected. The cond)ination of cement and amalgam, as described above fi)r occlusal cavities, may be used in tlie same manner in sim])le approximal Large occlusal cavity. Fig. 2-54. Section of cavity and fillinii. ZINC PHOSPHATE AND AMALGAM. 261 cavities in the molars and bicuspids, and even in the six front teeth, when the cavities are so situated that the amalgam does not show. When used in the front teeth the cement should be allowed to remain very near to the edges of the cav- iKJ^o5. ity. The amalgam need not be more in amount at this point than the thickness of an ordinary visiting card (see Fig. 255). For the front teeth very light colored amalgam should be selected, as color is of more importance than strength. In the temporary molars this combination can be used, many times, with the greatest satisfaction, espe- Combination filling in ^ _ •' ' ° _ _ ' i mcisor : a, enamel ; cialiy in those shallow approximal cavities where but &, cement; c, amai- little undercut can be obtained without exposing the ^^^' pulp. The cement should be used quite thin, and the amalgam worked into it with a burnisher, or rounded instrument, forcing the cement to a feather edge at the margins of the cavity. In cases of this kind resto- ration of contour should not be attempted, as the force of mastication might serve to fracture the cement and dislodge the filling. In this manner many troublesome and difficult cavities can be successfully treated, and teeth made to last their allotted time that would otherwise be prematurely lost. In Compound Cavities. — A more extended description will be necessary for the treatment of compound cavities in the bicuspids and molars, especially where it is desirable to restore contour. In these cases a matrix is often a necessity. There are many matrices that may be used successfully, but, as they are described in other parts of this work, only one need be mentioned here. This is selected on account of being almost universal in its apjjlication. It can be made from any metal not acted on by the mercury contained in amalgam. German silver is inexpensive and seems to meet every requirement, and is, therefore, recommended. For ordinary use it should be from jS!"o. 35 to No. 38 gauge. If stiff it should be annealed, so as to be readily bent to the form of the tooth. It can be easily polished so as to reflect light into the cavity, by drawing a narrow strip of it between two pieces of stationers' rubber (ink erasers). Place one piece of the rubber on a table, then the strip of metal held with pliers in one hand is placed on the cake of rubber, while with the other hand another piece of rubber is held firmly down on the metal, which is drawn between the two until sufficiently bright. For ordinary cases, a piece is cut from the German silver, as shown in Fig. 256, wide enough to extend from the top of the tooth to a little beyond the cervical wall of the cavity, and long enough to a little more than cover the cavity laterally when tied in place. Sometimes it is 262 CO MB IX A TlOX FILLINGS. necessary to make the matrix with a lip to extend under the gum, as shown in Fig. 257, or in some other irregular form, so that it can be Fkj. 256. Firi. 257. .Matrix and ligaiui( Lippeil matrix and ligature. Fig. 258. Manner of ligatintr the matrix. made to properly fit the cavity. Special cases may require a very wide or a very narrow one. The operator's ingenuity must devise the right shape. For tying the matrix to the tooth, coarse, well-waxed floss silk is the best, which is passed through the holes punched in the metal, as shown in Figs. 256 and 257. When these holes are made, the edges must be finished smooth, or the silk will be cut when drawn tightly around the tooth. The operator must use tact as to how and where to make his knots in tying on the matrix. Usually, a good way is to place one end of the ligature, a, between the teeth, then to make a sur- geon's knot, as shown in Fig. 258. The other end of the ligature, h, is then forced between the teeth, and the knot tightened. This will bring the knot between the teeth and opposite the matrix and will hold the latter until it can be shaped and bent into place with a burnisher or other suitable instru- ment. The knot is again tightened, and the two ends of the ligature carried to the back of the matrix and a similar knot tied there. The second knot, when drawn tightly against the back of the matrix, forces it closely up to the cervical border of the cavity, and makes a firm resistance when the filling is being condensed. The silk is then wound round and round the tooth and matrix until it nearly covers both, or at least sufficiently to ensure its remaining in ])lace during the oj^cration. A knot may be tied each time the silk is wound around the tooth, or not, as a])]K>ars to be necessary. Sometimes, when the sides of the tooth are sloping, the ligature has a tendency to slij) off'. This can usually be overcome by turning back, with tweezers, the two ujiper corners, as shown in Fig. 262. To saturate the ligature with sandarac or other sticky varnish will sometimes be sufficient to prevent the same tendency. When the cavity involves a large portion of the crown, or the mesial ZINC PHOSPHATE AND AMALGAM. 263 Fio. 260. Matrix with marginal slits. and distal surfaces, the matrix should be long enough to almost encircle the tooth, the ends nearly joining against the sound remaining wall (see Fig. 259). In such cases it may be desirable to slit it one or more times, in order that it may be made to take the form of ^ the tooth more easily (Fig. 260). After the tying is completed, a suitably shaped bur- nisher is used to form the matrix, by pressing it outward, to a proper contour. One of the desirable features of the matrix here de- scribed is the ease with which it is made to give just the right shape and contour to the filling. When used for gold fillings it yields enough so that with a little care in packing the gold can be forced beyond the margin of the cavity suf- ficiently to ensure a flush filling when burnished, after removing the matrix. A matrix put on as described will have sufficient resistance for a gold filling ; for amalgam, cement, or gutta-percha it may not be necessary to tie it quite so securely. For compound fillings of cement and amalgam two methods, A and B, are here given. A. Those cavities which, although large and involving much of the tooth, may have but small or comparatively small openings, especially if a matrix be used — and there are but few cases where the matrix is not advisable. If, after putting on the matrix, in this class of cavities, cement is introduced, and pieces of amalgam thrust into it, the cement will most likely be carried to the margin of the cavity at the cervical wall, and it ^11 be found, after removing the matrix and finishing the filling, that a part of the external portion is of cement, and not being protected by the amalgam, would be washed out. To avoid this, a portion of the filling is made before the matrix, is put on. Cement is put in, followed immediately by the amalgam as described for " occlusal cavities," with the added complication of the missing approximal wall. After sufficient amalgam has been put into the cement, the portion of the latter which may have oozed out must be carefully cut away, so as to expose the entire outer edge of the cavity, including the cervical wall (see Fig. 261). After this has been done, the matrix may be tied on and the filling completed as though it were but a simple cavity. Sometimes it is well to leave the matrix in place until the amalgam is fully set. If this be done, care must be taken that no sharp edge or corner of it be left to wound the tongue or cheek. Fig. 261. Cement lining and amalgam. 264 COMBINATION FILLINGS. Fig. 262. c. Portion of cavity to be nearly filled with cement and finished with amal- gam : 6, amalgam packed against the matrix ; a, mat- rix. Fig. 263. B. Cavities with large openings. The rubber dam and matrix having been adjusted, enough amalgam is packed againd the matrix to form a shell of sufficient strength to make the ai)proxim:il wall of the filling (see Fig. 261). This will leave a large portion of the cavity unfilled as shown in the figure ; in this space is placed cement, which is gently worked into the soft amalgam, but with care not to carry it through to the matrix. Before the cement be- comes hard, more amalgam is put in, the sur- plus cement is removed, and the whole finished to look like an entire amalgam filling, while in reality it is onlv a shell of amalgam, perfectly fitting the outside of the cavity, cemented into i)lace. If the walls of the tooth are frail, the cement will serve to greatly strengthen them. If, as some claim, large metal fillings alter sufficiently under changes of temperature to fracture frail walls, the danger is bv this method reduced to a minimum, as the amount of metal is only just sufficient to give requisite strength. There is another class of cavities which may be described in this connection, presenting great difficulties in themselves, yet, with this simple matrix, they are often easily filled. It is those cases where decay has reached the alveolar border approximally, and extended on cither the buccal or lingual portion of the tooth, or both, in such a manner that the dam cannot be made to stay beyond the cervical border of the cavity. If a liga- ture is used, it will draw into the lateral grooves of decay and be of no use (Fig. 263). The mode of treatment is as already described, with the exception that the matrix is adjusted before the j-ubher is jjiit on. After the matrix is in place, it is but the work of a moment to put a Palmer clamp on to the tooth, and slip the rubber dam over clamp, matrix, and tooth. If the matrix has been carefully fitted there will be no troul)le in keeping the cavity dry long enough for any ordinary operation. Tliere are certain buccal cavities, also, below M"hich it is diffictdt to retain the rubber dam. A very narrow matrix, adjusted with ligature and Matrix and clamp dam]) (Fig. 264), over which the rubber is placed, adjusted, ready for ^vill often iTivatlv sim])]ifv the oi)eration. Modifica- application of the . >• \ ■ ' i i i i i- i i dam. tions oi tJiis method may also l)e apj)lie(l to the a, Alveolar line be- yond which the liga- ture cannot be made to Slav. Fig. 2o4. CEMENT ANT) GOLD. 265 bicuspids, and sometimes even to marginal cavities in the incisors and cuspids, with good results. Cement and Gold. This combination may be used, with but slight modification, in the same manner and in the same class of cases that have been mentioned for the use of amalgam and cement, cases under B excepted. The cement is placed in the cavity, and, while soft, pieces of some of the so-called " plastic " golds are put into it, in the same manner as has been described for cement and amalgam ; the surplus cement is carefully cut away, and, after waiting for that in the cavity to become so hard as not to break or crumble under pressure, the pieces of gold placed in the soft cement are thoroughly condensed. For this pur- pose, Steurer's Plastic Gold, White's Crystal Mat Gold, Carpenter's C. P. Gold, and "Watt's Crystal Gold are recommended. The filling can then be completed with the same or any kind of cohesive gold. Care must be taken to place a sufficient amount of the plastic gold into the cement to make, when condensed, a solid foundation upon which to build the rest of the filling. If too little gold has been used, it will " chop up " and not make a secure union with the cement. In some large cavities it may be found more convenient, after having filled the approximal portion with the cement and gold, to make a second mix of cement for the rest of the cavity, into which the gold is put as before. In some special cases it may be well to use foil in this manner, but, as a rule, the jDlastic golds will be found preferable. Too much stress cannot be laid on the desirability of this method for frail teeth, remembering always that the cement is the strengthening and supporting medium. The mason would not build a bridge pier of granite alone, or a house of bricks without mortar. However nicely the blocks of granite or the bricks might fit each other, it is the cement and the mortar that hold them together as in one piece. Especial attention is called to this combination of gold and cement for the six front teeth. In the teeth of young patients, and those having teeth of low-grade structure there are often found large cav- ities that, if filled with gold alone, will in a few years, sometimes months, show discoloration around the fillings. If filled as above de- scribed, every vestige of decay having first been removed, a combination is the ideal preservative filling as far as present knowledge and fiicilities go. Pulpless front teeth that are much decayed can be improved in appearance and greatly strengthened by this method. Fig. 265 shows 266 COMBINATION FILLINGS. Fig. 265. Fig. 266. a cavity in a central incisor that can be filled to advantage with cement and gold. Fig. 266 shows a cavity in a central incisor with the pulp removed and but little of the crown remaining but the enamel. The greater part of the cavity has been filled with cement into which plastic gold has been put and condensed. The filling can be completed with any cohesive H'old. In compound cavities in molars and bicuspids, after the cement and gold have been put in, as descril)ed for cement and amalgam A, and the matrix adjusted, soft foil can be used to great ad- vantage at the cervical portion of the cavities, as elsewhere described for using soft and cohesive golds. a, a, Frail enamel walls : h, gold surface matle by- plastic gold condensed into cement. Amalgam and Gold. Gold may be used in coml)ination with amalgam — A, by allowing the amalgam to become hard before adding the gold ; B, by adding the gold while the amalgam is soft and finishing the filling at one sitting. A. Allowing- the amalg-am to harden and then adding- gold at a subsequent sitting will usually be done in c()in])()und cavities in bicus- pids and molars, for the purpose, principally, of overcoming the dark appearance of the amalgam. For instance, a filling involving the occlu- sal and mesial surfaces of an upper first molar will, in many mouths, show more or less, and, if of amalgam, be dark and unsightly. To avoid this, the cavity may be nearly filled with amalgam, leaving a })()rtion of the occlusal and along the buccal wall (this being the part of the filling most likely to show), for completion with gold later. The matrix should be used as described for cement and amalgam fillings. It is a good plan to leave it in place, when convenient, until the amalgam is hard. Before adding the gold, it should be ascertained what part of the filling will show, and the amalgam trimmed and shaped so that the gold may form that portion of the filling that will be in sight. Fig. 267 shows a compound cavity in a molar partially filled with amalgam. The amalgam has been left until hard and the filling is now ready to be finished with ffold. The fit>;ure also shows the cement lining under the amalgam. Suitable retaining places must be made in the amalgam to hold the gold in position, as there is no union between the two in this case, as there is when gold is added to unset amalgam. The gold being added makes a filling much superior in ap])earance to (^ne entirely of amalgam. The gold will also make a better wearing material for the masticating surface, having better edge strength than the amalgam, and therefore AMALGAM AND GOLD. 267 being less liable to be broken away from the Avails of the cavity by the force of mastication, as spoken of elsewhere. Large amalgam fillings, when it is not necessary to have gold added on account of color, will be greatly improved if a channel is made with a small fissure bur between the amalgam and the enamel, and this care- fully filled with gold. Fig. 268 also shows cement lining. Fig. 267. Occluso-approximal cavity partly filled witli amal- gam ready for completion with gold : a, a, amal- gam ; 6, cement lining. Fig. 268. Amalgam and cement com- bination with channel cut in occlusal margin for re- ception of gold : a, amal- gam ; 6, gold ; c, channel burred out ready for gold, shows also combination. Fig. 269. Gold and amalgam com- bination in incisor: a, amalgam ; 6, gold. All amalgam fillings when gold is intended to be added, should be put in with soft cement, whenever possible, as described for " Cement and Amalgam " fillings. This wall prevent much of the discoloration from the amalgam, as well as strengthen the teeth. Many front teeth can be saved and made to look well by filling with cement and amal- gam, as before described, and, after the amalgam becomes hard, cutting away that portion which is in sight, and filling with gold (Fig. 269). B. Amalgam and gold fillings, the gold being added while the amalgam is soft. These fillings will be indicated, usually, in com- pound cavities of the molars, and in the occluso-distal and sometimes even the mesial surfaces of the bicuspids. The amalgam will occupy not more than one-quarter or one-third of the approximal portion of the cavity, but sometimes in distal cavities of molars it may be good judgment to have as much as three-fourths of that portion of the fill- ing, amalgam. No operation requires greater attention to detail, or more neatness of execution, than where gold is used in conjunction with soft amalgam. If chips of the unset amalgam are left around the matrix, or in the folds of the rubber, or in any place where they may be caught up on the disk or finishing strip and rubbed over the surface of the gold while tlie filling is being finished, they will give it a coating of mercury and injure the appearance of the work. On the other hand, if the method given is followed carefully, no detail left out of account, no slovenly manipula- tion allowed to pass for neatness and tact in handling the materials, the 268 COMBTNATION FILLINGS. fillings can be finished as soon as the last piece of gold is consolidated, without the least danger of silver coating. In preparing the cavity for a filling of this kind, almost no tooth substance has to be cut away simply to get access to the cavity, to prop- erlv start and pack the filling, as is often necessary if an entire gold filling is to be made. As a consequence, much valuable tooth substance is saved, for, so long as the decay is removed and frail edge walls are cut awav, the amalgam can be perfectly packed, no matter how irregular the surfiice to which it is to be adapted. Of course, the excavation must be planned so that a filling of proper contour can be made, and walls cut back, when, by so doing, future decay can be better guarded against. There will be many cases encountered, however, where, by this method, much of a tooth structure can be left, whereas, if gold were to be used, it would be necessary to cut, often causing severe pain, in order that the part might be properly filled. For the ]niri)ose of describing a simple combination filling of this kind, a cavity involving the occlusal and distal surface of an upper sec- ond bicuspid is selected as an example. In the first place, sufficient space must be secured fijr a filling of the right contour, and to allow for passing in a very thin strip for finishing the filling. It is best to secure this room by previous wedging. Space having been secured, the cavitv is prepared with proper undercuts, and the walls of the approxi- mal part, to be filled with gold, made at as nearly a right angle to the matrix as possible. This is in order to facilitate packing the gold, it being very difficult to obtain a satisfactory margin if the walls form a very acute angle with the matrix. A matrix so adjusted that it will stand the pressure of putting in the filling M'ithout moving is an absolute necessity for this combination. It having been put on as described under the head of '' Cement and Amalgam" fillings (page 262), enough amalgam is carefully })acked at the cervical wall to fill one-finirth or one-third of that jiortion of the cavity. It should 1)e thoroughly consolidated by using properly shaped instruments and sufficient force to drive it into every part of the cav- ity. It is a good plan to use small pellets of bibulous paper, forcing them against the amalgam with medium-sized instruments. The free mercury which rises to the surface should be carefully removed. It is well to put in considerably more amalgam than is to be left, cutting out the surplus, which method leaves a good surfiice upon which to begin with the gold. Before the gold is added, however, care should be taken to remove every chip of soft amalgam from the folds of the dam, or any that may be clinging to tlie matrix, or in any position where it might be brought in contact with the gold when finishing the filling. These chips will remain for a long tiine soft enough to coat AMALGAM AND GOLD. 269 laro-e as the the gold with mercury if rubbed against it, therefore they must be disposed of or an unsatisfactory filling will be the result. The proper amount of amalgam having been packed in the cavity, medium-sized pieces of some of the plastic golds before referred to are immediately added. The instruments used first on the gold should be as cavity will accommodate, as they will break it up less and more readily carry the piece where it is wanted, after which each piece of gold should be thoroughly condensed with smaller instruments. As soon as the gold touches the amalgam it will absorb mercury, and sometimes several jjieces of the gold will be entirely amalgamated. The surface of the filling will be- come very granular, and " chop up " to a certain degree as the first pieces of gold are used, and the instrument will cause a peculiar squeaky sound as it is pressed against the filing. The condensation must be very thorough at this point of the work, or the filling will be porous and the union between the amalgam and gold unsatisfactory. If the work is thoroughly done, however, the filling will be just as strong at this point as any other. As piece after piece of the plastic gold is added, the mercury will soon cease to penetrate it, and the surface become entirely gold. As soon as this stage is reached, and no more mercury is visible, any kind of cohe- sive gold can be used for the remaining portion of the filling. Fio;. 270 will show some instruments that have been found especially useful in this work. The gold may be packed with hand or mallet pressure, or both. After the gold is all packed the matrix is removed, and the filling finished with sandpaper disks, strips, burs, and stones, in the ordinary manner. For finishing the amalgam portion of the filling only fine disks or strips should be used. The amalgam being yet in a granular condition, and not thoroughly hard, will be dragged from the edges somewhat and made slightly imperfect if a coarse grade of sand or emery paper be used. The gold will not break away from a filling made in this manner, even if there be no undercut in the tooth for holding it ; the union with the amalgam will be quite suf- ficient to retain it. The cavity must have the proper shape, Gold-pack- ing instru- ments. 270 COMBINATION FILLINGS. however, for holding in the filling as a whole, the same as if it were entirely of gold or amalgam. Cases may occur where it does not matter whether the amalgam and gold are firmly united or not ; then, instead of putting the plastic gold into the amalgam, soft foil may be used against it in the manner described for the combination of " Soft and Cohesive Golds." Having become familiar with the simplest form of fillings of amalgam and gold, it will be well now to go a step farther, and take up some of the complications that constantly occur. Even the small amount of amalgam that is used will sometimes discolor a tooth slightly, especially if the buccal wall is thin or if the tooth is not of very dense structure. When there is danger of this discoloration taking place, it can be largely prevented by placing a medium-sized pellet or fold of Fig. 271. foil, known as "gilded platinum," against the buccal wall of the cavity before putting in the amalgam. This foil being faced with platinum, which has but very slight affinity for mercury, the amalgam can be consolidated against it with little danger of discoloration following. On the mesial surface of bicuspids and molars it will a, Amalgam; 6, uot be cuough, always, to put the gold and })latinum foil guid extend- ^gaiust the buccal wall ; more or less of the proximo- ing on the '^ ' •■ buccal side buccal surface of the filling being exposed to view — /. e. gum margin'' ""^^ hidden by the tooth anterior to it — it would look badly if made of amalgam ; consequently, in these cases the gold must be carried to the cervical wall, as shown in Fig. 271, the amalgam occupying a triangular space. Cement, Amalgam, and Gold. There are many teeth with very large cavities and frail walls, that can be rendered serviceable for years and made to look surprisingly well by the use of this triple combination. For instance, a molar or bicuspid, having lost its pulp and a large portion of its crown, and occu])ying a conspicuous position, presents to the conscientious dentist a serious problem. He knows that if filled with amalgam it will be an eyesore to every one by its unsightliness. If filled Mith gold, it would take hours, and exliaust both patient and operator, and there would be every jirobability of the walls soon breaking away, and the filling com- ing out, testifying to the poor judgment of the operator in recommend- ing such a filling under such circumstaiiccs. If filled with cement it will have to be refilled often, and with each refilling would more than likely be somewhat weakened. The loss of contour by the wasting away of the cement will allow the tooth to change position, and its usefulness GUTTA-PERCHA AND CEMENT. 271 will gradually be lost, and the tooth sacrificed because the dentist did not bring the requisite amount of knowledge and skill to his aid to meet the opportunity offered. It is in saving such teeth as these that the reputation of the dental profession for skill and usefulness is in- creased, and honor and gratitude is accorded to the men who can accomplish it. The method of procedure will vary according to the size, shape, and position of the cavity. If small, a little amalgam can be put into the soft cement before putting on the matrix, as described for " Cement and Amalgam " A, the surplus cement removed from the entire edge of the cavity, the matrix adjusted, more amalgam put in, and gold added, as described for " Amalgam and Gold." In larger cavities, involving more of the crown, after having filled the approximal portion of the cavity with the cement, amalgam, and gold, cement should be put in a second time, into which plastic gold is carried, and the filling completed by building gold on to that which was added to the amalgam, and joining it to that which was put into the second mix of cement. In still larger cavities, the matrix can be put on first, amalgam packed against it to form the outer shell of the approximal side, as described for " Cement and Amalgam " B ; cement is then put into the body of the tooth, and into this gold is pressed {not amalgam) and afterward added to until it joins the amalgam, thus completing the metallic shell. From the specimen shown in Fig. 272 the matrix has been removed to better show the partially completed filling. It will be seen that the cement plays a very important part in this- operation. It will preserve the color of the tooth though it may have been necessary to use a little of the gilded platinum, or to have the gold extend to the cervical border of the buccal corner of the cavity to support and bind firmly together the tooth and filling, yet it is pro- tected from external influences which would destroy it. Fig. 273 shows section of a filling of cement, amalgam, and gold. Fig. 272. Fig. 273. a, Amalgam and gold to form approximal shell of filling; &, cement and gold to which is to be added gold to complete the filling. a, Cement ; 6, gold ; amalgam. Gutta-Percha and Cement. This combination is extensively used for what may be termed tem- porary work, in the teeth of young patients, in teeth of poor quality, and in badly decayed and frail teeth. 272 COMBINATION FILLINGS. It is generally believed that zinc phosphate will not last as well at, or just under, the gum margin in apprcjxinial cavities as will gutta- percha ; although exceptions might be taken to such a general rule. It is the common custom to coml)ine these materials, placing the gutta- percha at cervical margins, using the cement for the occlusal and con- tour portions of the tilling. There is no doubt that fillings of these materials last much better when inserted with considerable pressure, thereljy condensing well and making them solid. In accomplishing this, the matrix is of great assistance. It not only allows force to be used on the material while in a plastic state, but prevents its being crowded out of the cavity and up into the gum, and leaves the tilling in such condition that but little shaping and finishing are necessary. Anv suitable matrix — the one previously described in this chapter is recommended — having been adjusted, gutta-percha sufficient to fill the cavitv a little below the gum margin is carefully packed into place with warm instruments. Sufficient heat must be used to make it thoroughlv ])histic, ])ut great care must be taken not to l)urn or overheat the material. If the gutta-percha is overheated its physical properties and durability are very mndi impaired. All cavities where gutta-percha is used should be varnished with a thin coating: of white resin or Canada balsam dissolved in chloroform. This will prevent the dragging away of the gutta-percha from the walls of the cavity in finishing, and wall make the filling water-tight. Sufficient gutta-percha having been put in, the rest of the cavity is filled with cement. The matrix being in place and pro})erly shaped, the operation is reduced, practically, to that of filling an occlusal cavity. It is of great imjiortance that the cavities be kejit dry, consequently the rubl>er dam should be used wherever it is possible to do so. The cement should be kept dry for at least fifteen minutes after it is put in, and then covered with varnish or vaselin to prevent the disagreeable taste due to its acid reaction, also to keep the filling for a still longer time from the saliva after the dam is removed. Cement will wear better if smooth and well polislied. A fine glossy surface can be obtained with an oiled burnisher wlien tlie cement is at just the right degree of hardness, /. c when but slightly plastic. A convenient method of oiling burnishers and other instruments for plastic fillings is to place on the back of the third joint of the forefinger of the left hand a bit of vaselin, half the size of a drop of water, just before beginning to put in the filling. The instrument can l)e readily touched to this, and it (juite does away with the necessity for an '' oil pad." An excellent lubricant fi»r instruments used to manipulate gutta- GUTTA-PERCHA AND GOLD — VARIOUS KINDS OF GOLD. 273 percha or cement is cocoa butter. A small porcelain druggist's jar into which it has been melted is convenient to have on the operating table. Plastic tillings will rarely stick to instruments that have been rubbed on cocoa butter. If a shaving of it is placed on a completed cement filling it will instantly melt and flow over the entire surface, preventing the disagreeable taste when the dam is removed, and will keep it from contact with the saliva for some time. Gutta-percha and Gold. For many years it has been the habit of some good operators to fill the interior of large cavities with gutta-percha, covering it with gold. Although this may not be objectionable practice in some cases, it cer- tainly cannot be recommended for general use. The principal objection to it is the danger of frail walls being fractured by the subsequent expansion of the gutta-percha. So many instances have been noticed where fracture has followed this combination that the fact seems well demonstrated that this danger exists. Again, there is no need of com- bining these two materials when zinc phosphate, which is so much better tlian gutta-percha for this purpose, is available and does not pos- sess the dangerous quality of expansion attributed to gutta-percha. Gutta-percha and Amalgam. What has been said in regard to gutta-percha and gold will apply equally well to gutta-percha and amalgam. Rarely, if ever, can this combination be used to so good advantage as can zinc phosphate and amalgam. Various Kinds of Gold in Combination. (A) The So-called Plastic or Crystal Mat Gold, with Other Forms of Gold. — Within a few years, preparations of gold other than that known as foil, or foil made into cylinders, ropes, and so forth, have been introduced and have become of great value in the filling of teeth. These golds are commonly known as " plastic gold." The term is, however, misapplied. The granular quality of these gold preparations, i. €, lack of fibre, is what gives them their peculiar and, for certain purposes, very valuable working qualities. To understand this charac- teristic, take a piece of White's " crystal mat gold " and place it upon a piece of blotting paper, then press the point of a medium-sized gold packer upon the center. It will be observed that when the pressure is applied the gold is not inclined to curl up, but rests in its flat posi- tion, and the instrument has cut a clean track in the gold, condensing only that which is directly under the point. The gold being without 18 274 COMBINATION FILLINGS. " fiber," so to speak, the particles not directly under the point are not drawn down as the pressure is applied. This is why this preparation of gold is so useful for starting fillings. Now take a cylinder made of gold foil, place it on blotting paper as before, and with the same instrument press on the centre of it. It will be noticed that the instrument does not make a clean cut through the cylinder, as was the case with the piece of mat gold, and, instead of remaining flat on the blotting paper, it is inclined to curl up. The fibrous quality of the foil is an advantage when a corner is to be built on to a tooth, or in any place where toughness of the material assists in its manipulation. By using these golds for starting cavities, the peculiar qualities just referred to will be exhibited. For illustration, we will take an extreme case — that of a shallow circular cavity in the buccal surfoce of a lower molar. This cavity is entirely without angles or undercuts, its walls flarina: outward, the bottom being flat, *= . 1 • I Fig. 2/0. or as nearly so as it can be made w^ith ^^ « « \ V a large bur (see Fig. 274). A piece of ^k\ U^ \ '''^ plastic gold a little larger than the cavity is placed in position, then with Fig. 274. Royer plugging instruments. a flat, very slightly serrated instrument («, Fig. 270) it is carefully and gently worked into place. When it is condensed about even with the outer edge of the cavity, a smaller instrument is used to condense around the edge. As only the portion of gold under the ])oint is dis- turbed, this can be done quite readily without dislodging the whole piece. Soon sufficient force can be used to thoroughly condense the whole. Care must be used in selecting a first piece that it be not too large, but large enough, so that it will not chop up as it is being manipulated. After getting the first piece in place, the filling can be finished with the same or any other preparation of gold. If of the same, it is well to use oval points (Fig. 275) and work the gold toward the sides of the cavity with a sort of rotary motion, keeping the edges of the filling higher than the centre. This gold is very soft and takes a very sharp impression of the sur- VARIOUS KINDS OF GOLD IN COMBINATION. 275 face on which it is packed, as shown by the cross lines on the filling, a, Fig. 274, which are reprodnced from those made in the cavity shown at b in Fig. 274. The lines across the bottom of the cavity were made with the sharp point of a hatchet excavator. This form of gold can be used to advantage, sometimes, at the cervi- cal wall of compound cavities, provided a matrix has been tightly ad- justed. For starting fillings in approximal cavities in the front teeth it is sometimes invaluable, and it can be used in conjunction with any other form of gold, or interchangeably. If at any point in a filling the oper- ator sees a place where he thinks he can put a piece of plastic gold better than any other, there is no reason why he should not use it. Sometimes it is particularly useful to thrust into soft foil to make a sur- face upon which to build cohesive foil. It can be packed with either hand or mallet force, and with smooth or serrated instruments. (B) Non-cohesive and Cohesive Gold. — Strictly speaking, non- cohesive gold cannot be made cohesive by annealing, and can be used only on what is known as the " wedge " principle. " Soft gold," as the term is generally understood, is non-cohesive when used without anneal- ing, but when annealed it becomes cohesive. Softness and toughness are the qualities necessary to make tight joints between fillings and cavity walls, and good preparations of non-cohesive aud soft golds have these qualities. Consequently, a method that will admit the use of these golds against cavity walls with a sufficient amount of cohesive gold added to ensure strength and hardness, when strength and hardness are necessary, will be desirable. An exaggerated illustration of stopping a cavity watertight with soft or cohesive gold is that of stopping a bottle tightly by using a velvet cork or a piece of hickory. It can be done with the hickory, but the time required to do it perfectly, as compared with doing it with the velvet cork, is not unlike the difference between making a filling of soft or of cohesive gold. Simple cavities, whether in occlusal or approximal surfaces, can often be half or two-thirds filled with soft gold in a very few minutes, and the rest of the cavity filled with cohesive gold. A filling made in this manner is as good as, or even better than, one made entirely of cohesive foil, and the time required to do it is much less, as the soft gold can, on account of its softness, be used much faster than can the cohesive. In cavities of easy access the soft gold can be so manipulated as to be against the walls of the cavity at every point. Small cylinders, or any other form of soft gold, can be set around the edges, and the central portion of the cavity filled with cohesive gold. Care must be taken to carry the cohesive gold into the soft with instruments not too large, so that a mechanical union between the two golds is effected, as but little 276 COMBINATION FILLINGS. cohesion can be had between soft and cohesive gold. In large cavities, after the first pieces of soft gold have been pnt in place and cohesive gold worked in, the two kinds of gold can be nsed interchangeably. A piece of soft gold can be placed against a portion of the wall of the cav- ity, followed by a piece of cohesive, which is first attached to the cohe- sive portion of the filling and then used to force the piece of soft gold to its place. Dexterity and tact in using these two golds together can only be obtained by experience, and carefully noting the characteristics exhibited under manipulation. In compound cavities soft gold i)lays a most important part. Fill- ings in these cavities fail, usually, at the cervical wall, and too much care cannot be taken in making them at this place as nearly perfect as possible. For this purpose it is now generally conceded that soft gold is much better than cohesive. A suitable matrix will greatly facilitate the operation and assist in obtaining the proper contour. The thorough packing of the gold will also be much simplified if the cavity is so prepared that the walls form no acute angles with the matrix, therefore attention to this point is important. A matrix having been properly adjusted — the one described under "Amalgam and Gold" fillings is recommended — one-half or two-thirds of the approximal portion of the cavity is filled with soft gold. For this purpose soft cylinders, ropes, pellets, or mats can be used. Great care must be taken in condensing the gold that it does not tilt under the instrument. The pressure shonld fi)rce the matrix away from the tooth enough to allow the gold t(j be condensed just a little over the edge of the cavity, so that when the burnisher is a])plied there will be sufficient gold to make a flush filling. When all the soft gold has been put in that the case will allow, the cohesive gold should first l)e added in very small pieces in order to facilitate the driving of it into the soft gold, so as to make a strong union between the two. For this purpose very small cohesive cylin- ders or No. 3 or No. 4 foil w^ill generally be used, but sometimes No. 30 or No. 60 foil or some of the plastic or crystal gold can be used. The filling can be finished with any cohesive gold, that kind being selected which the operator has found by experience he can best manipu- late under the existing conditions. He will also remember, as the work go(>s on, that a piece of soft gold laid against an exposed wall, and backed up with cohesive, as before descril^ed, will do much toward securing a good filling. (C) Soft, or Cohesive Gold, and Heavy Gold. — Fillings of soft or cohesive gold, or a combination of the two, shouhl sometimes be finished with heavy f/old. Nos. 30, 40, 60, and sometimes No. 120, GOLD AND TIN— TIN-GOLD. 277 can be used to advantage. These heavy golds — which are usually rolled, not beaten — make a very dense filling, and, when great strength and hardness are required, they are preferable to lighter grades. When a filling that is to be finished with heavy gold has been brought to the point where the thick gold is to be added, the surface should be as nearly level as possible, as it is difficult to adapt the heavy gold to indentations and irregularities. The instruments used should have the very finest serrations, if any at all. The gold can be put on by hand or mallet pressure, or by burnishing with oval points having very slight serrations, or with an ordinary burnisher. When done in this way the burnisher is apt to become gold plated, and the instrument will stick to and drag away the gold. When this happens the gold plating can be removed from the steel by rubbing on a piece of ink eraser, or on flour-of-emery paper. In using heavy gold great care is necessary that no portion of the piece added be left uncondensed. Hard pressure must be applied to every part of the gold, or it will flake off and destroy the good appear- ance, if not the utility, of the filling. Gold and Tin. Compound cavities are sometimes partially filled with tin and then finished with gold. At the present time it is a disputed question whether tin, if used as above suggested, will not be dissolved out, after a time, by the action upon it of the fluids of the mouth, leaving a cavity. It can be used exactly as described for soft and cohesive golds, sub- stituting the tin for the soft gold, or for a portion of it — for, as a rule, much less tin would be used than soft gold. If desired enough tin can be used to cover the cervical wall, followed by suflicient soft gold to complete one-half or two-thirds of the filling, the final finish being of cohesive gold. The matrix will be found of the same service as in the case of soft and cohesive gold. Tin-Gold. The term " tin-gold " has been applied to the combination of tin and gold when a sheet of tin and a sheet of gold have been laid one upon the other, and rolled, folded, or crimped together, being then used in the same manner as non-cohesive foil, depending on the " wedge " prin- ciple for holding in the filling. Various authorities recommend diifer- ent proportions of the tin and gold to be used in this manner. All the way from one-quarter of tin to three-quarters of gold, i. e. the propor- tion of one-quarter of a sheet of tin and three-quarters of a sheet of 278 CO MB IN A TIOS FILLINGS. gold to be folded or crimped together, to three-quarters of tin and one- quarter of gold. A convenient May of preparing " tin-gold " for use Fig. 276. Foil crimpers. Fig. -27 Criinjifd tin in niedium-.^izcd cavities is to take one-third of a sheet of Xo. 4 tin foil, upon which one-third of a sheet of Xo. 4 non-cohesive foil is laid. It is then placed upon crimpers (Fig. 270) and drawn into an evenly folded mass (Fig. 277j. This is to be cut into lengths suitable to be used for the cavity in hand. These pieces can be doubled to make blocks, or rolled around a broach into cylinders, if desired. For larger cavities one-half, two-thirds, or even a whole sheet each of the tin and gold foils can be used. For very small cavities, one- quarter sheet of each may be sufficient. If it be a fact, as often claimed, that tin has peculiar preservative qualities as a filling material, it will be best to so crimji or fold the " tin-gold " that the tin will l)e on the outside, in order that it may be placed against the cavity walls. To obtain good results with this combination, it must be used with the same care and accuracy that are required for working gold. It is very tough and soft, and can be worked with great rapidity by an expert. For method of using see chapter on Xon-cohesive Gold, and work " tin-gold " as there described for non-cohesive gold. After a filling of " tin-gold " has been in for some time it will often be found to have changed in character, and instead of being a mass of malleable metal, as it was when put in, to have become hard and brittle, closely resembling amalgam, but, unlike it, will not stain or discolor the teeth. " Tin-gold " is recommended for use in the temporary teeth, in occlusal and buccal cavities of molars, especially in teeth of poor (pial- ity, and in the mouths of young patients. Small approximal cavities AMALGA3IS OF DIFFERENT QUALITY— CEMENT AND ALLOY. 279 in all the teeth may be filled with it to good advantage, when located where its dark color will not be objectionaiile. "Tin-gold" and Gold, — ''Tin-gold" can be used in connection with gold in the same manner as has been described for the use of tin and gold, or soft and cohesive golds. Amalgams of Different Quality in Combination. For certain amalgams is claimed a greater preservative character than is possessed by others. But on account of very dark color or little edge strength ^ they may be undesirable for the surface of fillings, especially when contour is necessary, or when prominently exposed to view. In simple cavities it is very easy to fill nearly full with the amalgam deemed best for its preservative cpialities, and to finish with that having superior color or edge strength as the case may require. For compound cavities fill about two-thirds with the first-mentioned amalgam, cutting away the surfaces and exposing the entire outer rim of the cavity, as shown in Fig. 267. The matrix is then adjusted and the remaining portion of the cavity filled with amalgam having the requisite edge strength for contour work. Cement and Alloy. Mixing alloys (such as used for amalgam) with cement has been recommended to a certain extent. This can be done by adding from 25 to 50 per cent, of the alloy fillings to the cement powder and then mixing with the licpiid, or the alloy may be worked into a thin mix of cement. The object of the alloy is to protect the cement, in a measure, from the fluids of the mouth, thereby making the filling more lasting. ^ See Chap. XT. also writings of Dr. J. Foster Flagg. CHAPTER XIII. INLAYS. By William E. Christensex, D. D. S. Although the terra " inlay," especially in Germany, has been api)lied to anything put into a tooth or the cavity of a tooth — medica- ment, gold, etc. — it has become customary to apply this name especially to such substitutes of lost tooth structure as are inserted into the cavity of a tooth in one solid piece. This method of restoring decayed teeth and preventing the recurrence of decay has been practised as long as has the art of dentistry. In the j)eriod of primitive dentistry teeth were filled by driving a solid piece of lead into the cavity — and doubt- less of a still older date are those greenstone inlays found in the central incisors of the skull of a man, found at Copan, Honduras, by Professor Owens a few years ago, and now exhibited in the Peabody ^luseum of Harvard College. At the present time inlays are inserted in preference to other kinds of fillings in two kinds of cavities, viz. in very large cavities where a specially hard and duraljle filling is needed to withstand the force and wear of mastication, and in cavities of the front teeth conspicuously located, when it is desirable to restore the tooth with porcelain of the same shade as the tooth. Many kinds of materials are used for making inlays, l)ut none serve the purpose as \vell as does porcelain. Gold inlays have been recommended, and arc still inserted by some dentists in large cavities — the idea being to save time and probably make a stronger or at all events a harder filling. The gold is fused into a matrix, made in sand and plaster from an impression taken of the cavity with wax or gutta-])ercha or with platinum foil burnished to the walls of the cavity, and tlie inlay when finished is set with cement. Such an inlay is inferior to a gold filling, made by packing the gold into the cavity, and ought not to be made. Amalgam inlays have been recommended for restoring large contours in the posterior teeth, and a few years ago such inlays were manufiictured and sold by the German dealers. They were filed into diiferent shapes 280 INLA YS. 281 and sizes, so as to fit all cases, exhibiting a polished, differently con- toured surface with a swallow-tailed catch on the back, and were intended to be set with freshly mixed amalgam. The value of such inlays is certainly questionable, since the filling made in this manner has no advantage over a common amalgam filling, and is not even as good. To restore a decayed tooth, not only to its original strength and usefulness but also to its original appearance, has always been the aim of the scientific and artistic dentist. As no material so far has been found which can be packed into a cavity, like gold, amalgam, or cement, and which at the same time resembles the tooth structure in appearance, various methods have been practised for grinding pieces of porcelain to fit into cavities and retaining them in situ with cement, or by packing gold around the edges. This kind of inlay work has rarely been prac- tised except in cavities in the labial surface of the upper incisors and cuspids. The best method for making them and for obtaining a fair fit to the edge of the cavity, is to take a piece of tin foil about No. 20 thickness, and after the cavity has been prepared (Fig. 278, b) and been Fig. 278. a bed e a, Defect at gingival margin; b, cavity prepared; c, mark of edge on tin foil; d, tin foil cut out and glued to artificial tooth ; e, piece of porcelain ground and cemented into the cavity. given as even and as smooth an edge as possible ; place the tin foil on the flat end of a clean rubber bottle-stopper and press it over the cavity, just enough to mark the edge in the foil (Fig. 278, c). Then carefully cut out the piece of foil and glue it to the surface of an artificial tooth (Fig. 278, d) which has been selected of the proper shade to match the case. The foil will serve as a guide for grinding out the section of porcelain, and a fair fit may be obtained if the work has been done very carefully (Fig. 278, e) ; however, such inlays are seldom satisfactory, and, besides, it is comparatively the most time-absorbing operation of all the inlay methods. Fig. 278 illustrates the steps of the operation. Many other methods for making porcelain inlays have been recom- mended, but all of them lack the essential qualities of a satisfactory operation. Ready-made porcelain inlays in different shapes and sizes, so-called porcelain stoppers (Fig. 279), can be obtained from the dental 282 INLA YS. depots. They are intended to be ground to fit a cavity, or the cavity must be shaped so as to fit the inlay. A set of instruments (Fig. 280) Fig. 279. © © 00 10000 V i/N^ y OOOOO Porcelain cavity stoppers. has been devised by Dr. Geo. H. Weagant. It consists of five tre- phines in different sizes, made of copper and charged with diamond dust. With these instruments pieces of porcelain can be cut out of an Fig. 280. Fig. 281. 1 LJ Dr. Weagant's diamond trephines. L)r. How's inlav burs. Fig. 282. artificial tooth so as to fit the cavity, which must have been prepared with one of Dr. How's "inlay burs" (Fig. 281), the corresponding sizes of trephine and bur being used. This method has not been used more than any of the others, it having several weak points. One of its worst and most strik- ing faults is that, in order to give the cavity the circular shape, a great deal of sound tooth structure must be sacrificed. For example, a cavity such as shown in Fig. 282, a, would have « ^ to be extended to the size and shape shown in Fig. 282, 6, for which reason but very few operators would recommend such an operation. One more kind of inlay may be mentioned which, though imperfect, INLA YS. 283 may perhaps have the merit of having led toward the final satisfactory solution of the question of how to make artistic and satisfactory inlays. It will be seen that the principal fault of the methods which have so far been mentioned lies in the difficulty of obtaining a satisfactory fit. This circumstance led to the idea of taking an impression of the cavity, either in wax or gutta-percha, from which a matrix resembling the shape and size of the cavity could be made in plaster and sand ; or a matrix was made by burnishing gold or platinum foil to the walls and edges of the cavity, and into this foil matrix the solid material could be fused so as to give a well-fitting inlay. This procedure, indeed, solved the question of obtaining an accurate fit, but it was of little value so long as only gold, rubber, or such kinds of material were used, which in no way resembled the appearance of the tooth structure, or which would give a better filling when packed directly into the cavity. About 1887 it was believed the right thing had been found, when Dr. Herbst of Bremen recommended the fusing of powdered glass into an impression or matrix taken with gold-platinum foil. The powdered glass was furnished by the dealers in several shades, and when fused it produced a somewhat transparent and most beautiful looking inlay, which when cemented into the cavity restored the tooth almost to its natural appearance. But the inlay under the action of the saliva soon lost its satisfactory appearance ; first it became opaque — then it lost its shade altogether, and even became black, and on occlusal surfaces it wore away like semi-hard amalgam. The powders for making these inlays are still in the market, and are sold also under the name of " Richter's Glasmasse" ("glass-body"). Other preparations of a similar kind are " Myers and Herbst's Venetian Enamel," which consists of powdered Venetian glass beads in a num- ber of different shades. The reason why glass and not ordinary porcelain was used, was the fact that the glass fused at a comparatively low heat. In fact, the manner of fusing them was that of simply holding the foil matrix, in which the powder had been placed, in the flame of a Bunsen burner, or even the flame of a small alcohol lamp would furnish sufficient heat to fuse it. But in order to render glass fusible at so low a heat, it must contain a large amount of flux, and this was the reason why the result- ing inlay, though it at first exhibited a smooth, enamel-like surface, be- came porous and unfit to resist the action of the saliva. On the other hand, porcelain requires a very high degree of heat for fusing, and could not be used without a suitable furnace, which could hardly be used in the dentist's office or laboratory. Such a furnace, however, was constructed and sold to the profession by Dr. C. H. Land ; its comparatively high price was, however, an obstacle to its 284 lyLA YS. general adoption. Since the Downie Crown-furnace and furnaces of its type, also the Custer Electric Oven, have been put upon the market, porcelain inlays are becoming parts of the daily work of the artistic dental operator. Selection of Cases. One of the most important points in connection with porcelain inlay- ing is to select the cases very carefully. Porcelain inlaying is not a type of work applicable to all classes of cavities. There are only three kinds of cavities for which it may safely be recommended : (1) Cavities on the hd)ial or buccal surfaces of all teeth which come into view in talking or laughing. (2) Large approximal cavities, especially those in tlie central incisors and cavities, and in the mesial portions of the first l^icuspids. (3) Large cavities in the first permanent molars, when one or more of the walls and large portions of the occlusal surface have been destroyed, and the cavity involves almost one-half or more of the entire crown of the tooth. The larger the cavity is, the greater is the value of the porcelain inlay ; at the same time it becomes easier to make, and saves the dentist and the patient time and trouble, and furnishes the strongest and best- looking kind of a filling thus far attainable. Preparation of the Cavity. Before taking the impression the cavity must be carefully excavated, cleaned, and suitably shaped. The margins must be given special atten- tion ; those of buccal and labial cavities must be evenly smoothed with large round finishing burs, and all sharp corners must be removed. The edges of approximal cavities and those in the molars are best smoothed with sandpaper disks or carborundum stones of fine grit. Slight undercuts, merely to hold the cement, should be made only after the impression is taken. The walls may be bevelled outwardly for a like distance from the margins, so that when the platinum of the impression is removed the inlay will fit tightly on the margin at the bevel and will set into the cavity the tliickness of tlie platinum removed, thus taking up the space occupied by the foil and making a perfect fit. For large approximal contour fillings the cavity must be given a deej) undercut at the cervical portion, to serve as a retaining groove for the inlay. In Fig. 283, a shows in section the prepared cavity of a central incisor for a large contour inlay ; b shows how the inlay must fit into it ; c and d are views of a laV)inl cavity, j)r('parcd and with the inlay in position. If the pulp has been destroyed the cavity can TAKING THE IMPRESSION. 285 be extended into the pulp chamber, so that the inlay will have a still stronger hold. When a large approximal contour has been destroyed by caries, the teeth will usually be found to have moved together. In such cases gradually separate the teeth with rubber as much as possible, then insert the inlay, restoring the full contour of the tooth, so that the inlay, when the teeth move together again, has an additional support from the pressure from the neighboring tooth. Taking the Impression. Different methods have been recommended for taking impressions of cavities in teeth, but none is as simple and as reliable for our pur- pose as is that of pressing a sheet of platinum foil into the cavity, bur- nishing it close to the edges, and baking the inlay in the matrix thus obtained, without investing it in plaster and sand or any other material. If an imjjression is taken with wax, or gutta-percha, or with foil and wax, or in fact whatever kind of an impression is taken except it be with platinum foil, a plaster-and-sand matrix must be made from it into which the porcelain is fused, but which on account of the expan- sion and contraction of the plaster and its probable cracking will never give as satisfactory results as when the porcelain is baked or fused directly in the platinum matrix without any investment. Dr. Genese of Baltimore recommends that the impression be taken with No. 4 gold foil, filling it up in the cavity with wax or gutta- percha, and investing it in j^laster and sand ; then removing the wax or gutta-percha, leaving the gold foil in position and fusing the porce- lain in this matrix. He uses a body containing flux enough to make it fuse at a lower heat than the gold. This method is a return to the point where Richter and Herbst started, and can only result in the same kind of failures as have already been described. The fusing-points of all kind of porcelain bodies are far above that of gold, and if reduced to fuse below that degree they are rendered incapable of withstanding the action of the fluids of the mouth. If, on the other hand, the gold melts, it will combine with the porcelain, so that the back and the 286 INLA YS. edge of the inlay acquire a pink shade. Even platinoiis gokl (" clasp metal") fuses at a lower heat than the Downie porcelain bodies. To take ihe impra^sion, and at the same time make a matrix, pro- ceed as fjllows : After the cavity has been prepared, take a i)iece of pure platinum foil considerably larger than the cavity. According to the size of the cavity use thin or thick foil. The thinnest, which may be used for the smallest cavities, resembles gold foil No. 20 ; the thickest, which is used for large cavities, resembles gold foil No. 60. The foil must be well annealed to make it as soft as possible. In order to introduce the foil into the cavity without tearing it or pressing the instruments through it, fold it up in a triangular shape (Fig. 284) and introduce it into the cavity as shown in Figs. 285 and 286, holding Fig. 284. Fig. 285. Fig. 286. Platinum foil folded for introduction. Mode of introducing foil. it with a pair of ])liers, and with a second pair of pliers, which must not be very pointed, press small cotton balls, of a size corresponding to the size of the cavity, into the foil matrix, pressing the foil against the bot- tom of the cavity. The foil, when folded as indicated, will reach the bottom and spread to the walls without tearing. AYhen a sufficient impression of the cavity has been obtained to secure for the inlay a good hold, bend the foil over the edge, and Avith a smooth Herbst's burnisher secure a sharp and exact mark of the edge. The exact impression of the edge is the most important part of the whole procedure. In using- the burnisher do not use it with the engine, but work by hand pressure only. Tiie matrix may then be removed from the cavity, and the excess of foil should be trimmed off a little distance from the mark of the edge, then it should again be placed in the cavity and be pressed into position with a piece of caoutchouc, which must be large enough to cover the whole edge of the cavity at once. The rul)ber sliould be manipulated so as to exercise a uniform pressure at once over the Avhole matrix, wiiich will secure a most perfect impression. The matrix should then be removed, and great care must be taken not to bend it when intro- ducing the body into it. It re<|uires some {)atience and practice to THE BAKING. 287 handle it successfully ; however, the platinum foil is pretty stiif, and a skilful operator soon becomes able to manipulate it without bending it. If the cavity is an approximal one, the foil must l)e folded as shown in Fig. 284, and the rubber should be cut in the shape of a wedge, and used as shown in Fig. 287. Although the best results are invariably obtained by baking the porce- lain in the foil matrix without investing the matrix in plaster, it sometimes becomes neces- Fig. 287. sary to use an investment ; for example, when the thinnest foil is used for a very large cavity, or when the foil, in spite of all care, may have torn at the bottom, etc. If the student has not had any experience in this line of work, he should never use the thinnest foil Vvdthout in- vesting it. In this case the matrix, before its removal from the cavity, should be filled with gutta-percha or with yellow wax, which must showing rubber Avedge m not be heated, and the investment used should be two parts of plaster to one part of asbestos fiber. The fiber should not be used just as obtained from the depot, but should be cut so as not to be longer than from one-twelfth to one-sixth of an inch. This is easily accomplished by taking a bulk of the fiber as large as a walnut and cut- ting it with a pair of sharp scissors. Before proceeding to the baking of the porcelain, the investment should be allowed a day or two ta become entirely hard. The Baking. The baking or fusing of porcelain inlays is a process similar to that of baking continuous gum work or porcelain teeth, consequently any furnace used for these purposes can also be employed in baking inlays • but, for obvious reasons, it is advisable to use a smaller — in fact, the smallest obtainable furnace capable of developing sufficient heat to fuse the porcelain. A furnace without a muffle should not be used, for the reason that if the flame comes in contact with the porcelain it will stain its surface. This will even occur sometimes when a muffle is used, if the latter is not sufflciently tight — especially with clay muffles, which easily crack or on account of their porosity permit gases to pass through the walls. For this reason it is preferable to use platinum muffles. The Downie Crown Furnace (Fig. 288) has a muffle of platinum, ^ in. wide by f in. high, around which the heat is concentrated. It is designed for baking crowns and porcelain inlays, being just large enough to admit of such work, and to do it in the shortest possible time. 288 ISLA YS. It will fuse the porcelain in from one and a half to three minutes according to the size of the work. Fk;. 28S. The Downie crown furnace. Fig. 289 shows the Custer Electric Furnace, which is admirably ada])tcd for making inlays, as the source of lieat is under perfect con- trol and there are no products of combustion to produce injurious effects upon the texture of the inlay. The porcelain body is obtained in the form of fine powders. The Downie bodies come in twenty-four shades, with which, when proj^erly applied or mixed, almost any desired shade can be obtained. One pure shade will seldom match the tooth well, but in mixing yellow and gray, or light brown and blue in different proportions, shades can be developed to match the natural tooth almost to perfection. The mistake of select- ing too light shades is usually made by operators inexpert in this kind of work — the inlays look better in the mouth when they are darker rather than when lighter than the natural tooth. It must also be borne in mind that teeth are darker and more yellow near the gingival margin, so that, when a large cavity occurs in that portion of the tooth, the THE BAKING. 289 inlay must usually be made more yellow than the portion of the tooth near the cutting edge. When the matrix has been prepared, the body should be mixed with distilled water to a cream-like consistence, and should be introduced Fig. 289. Custer electric furnace. into the matrix with a small pointed camel-hair brush, or, better, with a pointed steel instrument. Care must be taken that the body reaches the bottom of the matrix. Dry powder can then be added, as much as the water will absorb. If the matrix be held with a pair of pointed tweezers, and the tweezers tapped with the handle of an excavator, the body will settle down and the Avater will come to the surface and render it smooth. On account of the contraction of the body, the matrix must 19 290 INLA YS. Fig. 291. ^<2>^ Showing methud witli extra large contours. be only a little more than half filled for the first baking. Two, or as a rule three bakings are necessary, and only at the last baking should the powder touch the edge of the matrix. This is because the body in fus- ing adheres to the platinum and would contract and change its shape if tlie edge had not been left free and the body shaped so as to have a convex surface. Fig. 290 shows in diagram how the powder should be shaped in the matrix, a, before the first baking ; b, before the final baking. If the surface of the body is con- vex before the baking, it will be found to be flat when fused and will not have contracted the matrix, whereas if it is flat before it will be concave after the fusing ; besides, it will have contracted the matrix. If a large contour is to be made, body should be added gradually and baked several times until the desired contour has been obtained. Only with very large contours it is advisable to mould the section in wax or gutta-percha, and to invest it together with the matrix in plaster and asbestos, covering the back part of the contour, so that when the wax is removed the investment forms a base and a guide for the correct size and shape of the contour (see Fig. 291). Before starting the baking, the furnace should be well heated, then the section should be put into the muffle and allowed one-half to one and a half minutes to become dry and slowly heated ; if it is heated too quickly, the steam from the water is apt to throw the body out of the matrix. If the matrix has been invested in plaster, about three minutes will be necessary for fusing the Downie porcelain body, whereas one and one-half minutes is sufficient if there is no plaster investment to withdraw the heat from the body. If the matrix has not been invested, it should be placed in the muffle on a small platinum tray filled with powdered silcx, but if invested it should be put at once into the muf- fle without the tray. The focus of highest heat is about midway be- tween the middle and the back of the muffle. The muffle need not be closed during the baking, so that the operator at any time can over- look the work. The porcelain will be tougher and of a better appear- ance if allowed to remain in the muffle and cool down slowly after each baking. Setting the Inlay. After the baking the platinum of the matrix sticks considerably to the porcelain ; however, it may be removed by simply pulling it off" with the finger nails, or the rim of the matrix may be twirled around the SETTING THE INLAY. ' 291 points of a pair of pointed tweezers ; when this is carefully done the foil can be pulled off without injury to the inlay. Otherwise it may be re- moved with a corundum wheel, but it should always be removed from the edge by pulling it off or scratching it off with an excavator. The edges of the inlay will usually exhibit a slightly jagged appearance, which should be carefully smoothed with a cuttlefish disk or an Arkansas stone. Inlays in the front teeth should always be set with dental cement. The Harvard cement being the most sticky and plastic variety, is the best suited to the purpose. It should be mixed to a cream-like consistence, as when used for setting crowns and bridges. When the inlay fits well, very little cement is needed ; only sufficient to fill up the space be- tween the inlay and the wall should be put into the cavity previous to the inlay, since an excess might prevent it from setting into its right position. Approximal inlays are best forced into position by means of a wooden wedge, which may be ^^' left between the teeth to hold the inlay securely for a day's time — it is also well to leave the excess of cement over the joint for the same period. If the inlay fits properly, the joint will be scarcely notice- able (see Fig. 292), and the cement is not liable to wash out, since there is hardly any surface for the saliva to act on ; however, should it wash out, the joint may at a later date be filled up with a cement ^^^'^'^ pj.opgj.iy fluted of a stiffer mix. In the construction of IcM^ge inlays in the molars, a wide joint may be made purposely by using heavy foil for the matrix, and when the inlay has been set with cement the surface of the joints should be cleaned out with an excavator or with a very small bur, and filled uj) with amal- gam. In this manner the washing out of the cement is absolutely prevented. An additional hold for the inlay can be obtained by placing a ball in proportional size of plaster of Paris on the bottom of the matrix before the introduction of the body ; when this plaster is after- ward removed there will be a retaining groove in the inlay itself (see Fig. 291). If the inlay is a flat one, a similar hold can be made by placing some coarse sand on the bottom of the matrix, but very great care must then be taken not to get the sand mixed into the body. If the tooth is a pulpless one the pin of an artificial tooth may be baked into the inlay so as to extend into the pulp chamber. Porcelain inlay work can only be successfully done by the operator who devotes to it much time, patience, and care, with the observation of an endless number of small details ; where it is undertaken merely for the purpose of saving time and money the result will be failure. 292 INLA VS. Gold Inlays. The same principle of operation as that described in connection with porcelain inlays may be applied with gold as the fusible contour material instead of porcelains, and using the same form of platinum matrix. This method and modifications of it have been followed to a limited extent, but owing to faulty methods of design have not had the wide application which they deserve. Dr. C. L. Alexander' has furnished descriptions of methods and technique, which materially widen the field of application of the general principle. The substitution of gold for porcelain permits the use of types of contour restoration whicli would not be admissible with porcelain, owing to the brittleness of the latter material ; as for example, the occlusal edges and masticating surfaces of teeth which it is possible but inex- pedient to restore by means of gold foil (Fig. 293). Fig. 293. Showing details of the process for making cast filling for incisor: a, Post with plate adapted; B, restored contonr in wax ; c, the contour invested ; d, cast contour detached ; e, e, the finished restoration. The method is applicable to pulpless teeth or those containing vital pulps. In the former case anchorage for the piece is secured by means of a post which occupies the pulp canal, as shown in A, Fig. 293. The tooth is prepared and its edges formed as represented at a. Thin platinum plate, of gauge not less than No, 40, is to be Avell annealed and pressed into contact with the pre]iare(l edges and surfaces of the tooth ; the adaptation must be perfect. The plate is punctured at the site of the enlarged pulp canal and a platinum post inserted as shown in cut. Softened modelling compound is pressed over plate and ])ost which in hardening holds the pieces in correct relative positions. The piece is invested, and the post soldered to the plate by means of 24-karat gold. Returned to the tooth the platinum plate is burnished to close adaptation and a bite and impression are taken ; the piece being withdrawn in the latter. A cast is made of sand and ))lastor, and an articulation mounted. Upon the platinum base hard wax is l)uilt until the contour of the 1 Dental Comios, ()ct()l)er, 1890. OOLD INLAYS. 293 tooth is restored. Around and over the wax, which should be chilled, platinum foil is burnished, covering all of the wax except at one wall. The model tooth, with the platinum base and wax form, is cut from the model and the piece invested, being entirely covered by investing mate- rial except at the uncovered wax surface. The wax is boiled from the metallic matrix, which is then filled with pieces of 22-karat solder ; the investment is well heated, when a fine blowpipe flame directed into the matrix fuses the gold. More solder is added until the matrix is full : 22-karat solder, or better 23-karat solder, is preferable to 24- karat gold for this purpose, as the latter in fusing may appear upon the under surface of the platinum and destroy the adaptation. Removed from the investment the piece is filed to its correct lines and smoothed and polished. It is then cemented to its position, and when the cement is perfectly hard a final finishing is given. Fig. 294 ^ shows the method of restoring a broken-down bicuspid. Fig. 294. Fig. 295. Kestoration of bicuspid by cast filling. Front and back view of an incisor restoration, and cast filling for molar. Fig. 295^ shows the application to vital teeth. The pits for the reception of the pins in. these cases are to be at such points, and of Fig. 296. Foil matrix invested. Cast filling for molar. such depth, that the pulp is not endangered. Fig. 296 ^ shows another useful application of this method. The pieces may be made to serve as efficient abutment pieces in bridge work. 1 Ibid. CHAPTER XIY. THE CONSERVATIVE TREATMENT OF THE DENTAL PULP. By Louis Jack, D. D. S. As the dental pulp by its supply of nutritive pabulum maintains the vitality of the dentin and increases the resisting power of the tooth, it is important when this organ becomes exposed to agencies which threaten its destruction, to attempt its preservation when the condi- tions are favorable to that object. A further reason for maintaining the vitality of the dentin is that when the pulp becomes devitalized the loss of cohesive force which occurs as a consequence leads sooner or later to the fracture and early loss of the tooth — this final result being delayed in proportion to the inherent strength of the tooth and the period of life at which devitalization takes place. The treatment of teeth when the pulp has been approximately reached by the invasion of dental caries has been previously consid- ered (Chapter V.). Here will be set forth a rational line of treatment when the carious action has encroached upon that organ. Normal Characteristics and Pathological Tendencies of THE Dental Pulp. The minute anatomical elements of the dental pulp are given in Chapter II. and in treatises upon dental histology. The salient fea- tures of these elements which have to be kept in view in connection with treatment are — (1) The minuteness of the apical foramina, which restricts the cir- culation, wOien the vascular phenomenon known as " determination " occurs. (2) The ultimate nervous distribution immediately beneath the odon- toblastic layer, forming a plexus which renders the whole surface of the organ highly sensitive when the blood supply is increased as the effect of irritation. (3) The arrangement of the capillary circulation in loops which arise from the vertical vessels. This relation of the vessels lessens the tend- ency to inflammatory diffusion. 294 PATHOLOGICAL TENDENCIES OF THE PULP. 295 (4) The absence of lymphatics, which deprives the pulp of the power to remove inflammatory effusions or to convey insoluble medicaments. It should be noted that the pulp in a normal state is not a highly sensitive organ, but is rendered exquisitely so by the irritation from external chemical and infections influences incident to its exposure, and that it is under all conditions so extremely impatient of compression that a severe shock of that kind renders recuperation nearly impossible. This is probably due to the liability of disconnection of the pulp with its walls at some point on account of its feeble attachment to them. The pathological tendencies of the pulp under irritation are — (1) To hyperesthesia. (2) To circumscribed hyperemia under slight irritation. (3) To congestion or mechanical hyperemia under increased irrita- tion which terminates at length in stasis by the restriction of the circulation. (4) To proliferation of the deeper tissues as the result of latent con- gestion attended by fatty degeneration of cells and the development of dentinal nodules — pulp stones. A further important consideration connected with the treatment of the pulp is the indication presented by a state of the teeth designated as the " temperature sense." This is a variable condition with different individuals, some being able to apply the coldest water in the mouth and to crunch ice without pain, whilst others whose teeth are sound are impatient if cool water is brought into direct contact with these organs. This kind of irritation of the teeth appears to be a function of the stratum granulosum, since the effect is produced immediately upon the application of low temperature to the enamel. When irritation of the pulp occurs this sense is exaggerated in the individual tooth. This variation from the normal, as determined by a comparative test of the sound teeth, becomes an important diagnostic indication, as will appear later. A further pertinent consideration bearing upon the various condi- tions of the exposed pulp, as shown by the symptomatology, is here in place. It has already been indicated that when the exposure of the pulp to irritation has been slight — that is, where this organ has been measur- ably protected from exterior influences by the covering layer of incom- pletely decalcified dentin — the pulp is ordinarily but slightly affected. When the denudation has become complete and the amount of pulp surface in contact with the carious matter has become considerable, and further, when by the solution and displacement of the carious matter the influence of the contents of the mouth is direct, the disturb- ances of the pulp become progressively increased. In the light of pres- ent knowledge of these injurious influences the causes of their operation 296 COySERVATIVE TREATMENT OF THE PULP. must be attributed to infection of the pulp by the various minute organ- isms which have their habitat in the mouth. The pulp tissue becomes infected in the degree to which it is exposed and in proportion to its power of resistance to the pathogenic character of these forms of life. It is axiomatic that the activity of inflammatory processes is usually in proportion to the degree and the kind of infection. Therefore it must be held here as elsewhere in surgical procedures that the existence of infec- tive influences and their control have to be kept clearly in view. This consideration enables us to understand the causes which render conservative treatment inoperative, in cases in which there has existed for a considerable period the opportunity for active invasion of the pulp by micro-organisms. When these deleterious influences have long con- tinued, the deeper tissues of the pulp, as before stated, become involved ; the chief factors producing the disturbed state eventuate in a sujjpura- tive condition — which is only a form of expression for invasion by pyo- genic germs, the inflammatory processes attending this condition being superinduced by the peculiar irritation caused by the infection. This results in some instances in stasis folhjwed by gangrene ; in other cases, where the arterial tension has not been great, in suppuration. The cha- racter of the suppurative process, rarely, is a circumscribed abscess of the pulp, the more common form being by progressive and destructive ulceration of the organ. Fig. 297 (after xVrkovy) shows the phenomenon of invasion of the pulp by micrococci.^ In the treatment of an organ which cannot be brought under ocular inspec- tion, the chief guides to determine its state are the apparent conditions — the peculiar circumstances in connection with the symptomatology of the case under treat- ment. The above-stated anatomical relations, physiological qualities, and pathological tendencies have an interesting bearing upon conservative treatment of the pulj). Exposure of the Pulp. — As an indication of the tolerance of the pulp to the approach of caries it is a common experience that after solution of the enamel has taken place, caries of the dentin proceeds until the pulp is nearly reached by the destructive process with little or no signs of irritation, as evinced by pain, appearing. It is the excep- tion that even persons of high nervous sensibility are cognizant of the ^ Tn this connection see Micro-orrjanisyns of the Human Mouth, by W. D. Miller, pp. 293-295. Fig. 297. Invasion of pulp by micrococci. METHOD OF OPENING THE CAVITY. 297 influence of the carious process upon the pulp previous to actual encroachment. In the earlier stages of exposure the elements of the organ involved are its peripheral nerve filaments, which are hyperesthetic from the hyperemic state of the organ immediately adjacent to the point of encroachment. At this stage the pulp becomes impatient of cold, and may indicate the nature of the lesion by reflex pain in other branches of the trigeminus. Later on, unless these conditions are subdued by treatment congestion of the organ takes place, when objective symp- toms in the organ itself may be elicited. This is shown by some sore- ness upon percussion, accompanied by pain on the application of heat. These indications point to a greatly increased blood supply. Dila- tation of the arterial trunk of the apical space occurs, and the blood being unable to enter at the foramen is distributed to the peridental membrane. These manifestations indicate that the point of danger has approached. Soon thereafter congestion becomes so far estab- lished that prospect of successful conservative treatment vanishes. When patients are under frequent observation and have regular and periodical care taken of the teeth the pulp exposures which occur should be found in the hyperemic state, and if placed under treatment early after the carious action has approached the pulp, the prognosis should be favorable. But when neglected cases appear the history of which is obscure, and where the patient is forced to seek relief by the occur- rence of objective symptoms as narrated above, accompanied by local pain and pulsation, the indications point to devitalization and extirpa- tion as the suitable recourse. The exposure of the pulp is often discovered in the treatment of ordinary cavities in a somewhat unexpected manner, no indications appearing until the part is uncovered, or a variety of subjective or objective indications may be elicited which plainly point to this con- dition. At the commencement of the treatment to restore the lost tissue in any given carious tooth, except in very small cavities, the proba- bility of encroachment upon the pulp should be a supposition, and each step should be made with reference to this probability. The destruc- tion of the dentin is frequently surprisingly deep, or the cornua of the pulp may be acutely pointed and may be unexpectedly encountered. Therefore, in what may seem simple cases, cautious approach should be made toward the bottom of the cavity. Method of Opening the Cavity. The opening of the cavity should be effected by instruments which will not easily enter the cavity, and the softer caries removed in a 298 CONSERVATIVE TREATMENT OF THE PULP. manner which will not induce pressure of the carious matter upon the pulp. For this reason, in the removal of the caries the excavation should be first carried on at the sides of the cavity, and also along the margin of the cervical wall in approximal cases. Then the carious matter nearest the pulp should be carefully peeled off without pres- sure and without irritation. In this manner a pulp may be uncov- ■ered and the cavity cleansed of carious matter without contact being made with the pulp. To do this is the acme of skilful preparation. The instruments for removing caries should be of thin edge, very sharp, and always having cutting surfaces which are rounded, since angular or square-ended excavators are liable to make exposures un- necessarily. It is important that the direction of movement of the ex- cavators should be from the cervix toward the occlusal part — in other words, by drawing cuts instead of pushing cuts. The difference in the excitement of pain between these two methods of cutting is surprising, and can only be appreciated by those who have experienced the com- parison upon their own teeth. The probable reason for this is that the force of the pushing cut is necessarily greater, and this direction may induce compression of the caries or of fluids against the pulp. It causes more pain at the moment, and the cleansing in this manner is followed by greater after-irritation. Patients will complain at the time of reflected pain being caused by pushing cuts. It is obvious that every mode of procedure which increases the local irritation in the preliminary procedures of a pulp treatment must be deleterious in its results. The danger of making accidental exposures and of forcing the instruments upon the pulp are increased under push cutting. It is also clear that the use of burring instruments upon the pulp wall of cavities is questionable, since the infliction of some com- pression by excavating in this manner is nearly unavoidable. Here an interesting question appears : A cavity may be sufficiently deep to cause an exposure ; it has been carefully cleansed of caries, and the cor una are not apparent. It is then necessary to determine whether there is a real but minute exposure or whether there is a safe amount of healthy dentin to protect the pulp beneath the stopping material. One method is to cro.ss-hatch the cavity by a very fine explorer. This is effected by holding the instrument very lightly and passing it gently over the surface in parallel lines in two directions. If the pulp has been reached, the instrument at the point of encroachment will lose its resistance or will drag the point of the cornu, as the case may be. While there may ho no visual evidence of exposure, the certainty of it is frequently shown during the prej^aration of the cavity or the test- ing by a peculiar expression of the face of the patient, different from METHOD OF OPENING THE CAVITY. 299 that manifested by the cutting of the most exquisitely sensitive dentin. This change of the countenance, accompanied by a slight start of the features^ may occur without the recognition of pain. This indication sometimes appears previous to the removal of all the caries ; it is then probably caused by some tension of the apex of the cornu produced by the disturbance of the carious dentin. The influence of cold constitutes another test of exposure, Avhich may be applied in doubtful cases, and may often be used to determine the probability of exposure before the treatment has commenced. This is of assistance when the cause of reflected pain is occult, and w^here we have to determine whether the pain, amounting almost to a tic, is caused by a disturbed pulp, or is brought on by malarial influence or a visitation of gouty neuralgia. The effect of the influence of cold applied to the enamel has been alluded to as indicating an actively hyperemic and consequent hyper- esthetic condition of the pulp. The irritability of the teeth to cold, whether it appears naturally or in an aggravated degree, is conveyed through the enamel, as heretofore stated, and in the latter case is a positive sign of disturbance not to be mistaken. By means of it the earliest stages of pulp excitement may be determined by isolating the suspected tooth and making a test. The test is made by passing it through a piece of rubber dam. If carious the cavity should be slightly closed with varnished cotton, when cold water or a piece of ice is applied to the enamel. In making this trial the adjacent sound teeth should be tested to attain a comparative result. This is necessary because of the varying degree of normal sensitivity of different persons. The use of this is also of value to determine whether any given irritation in doubtful cases is dependent upon the condition of the teeth. If the case is one of malarial or gouty origin, the teeth do not abnormally respond to the cold test. Another diagnostic sign of pulp irritation is the occurrence of pain, usually of a reflected character occurring in the evening. On the contrary, neu- ralgic attacks dependent upon malaria or gout are more frequent in the early hours of the day. The stages of pulp exposure are divisible into three periods — (1 ) of quiescence ; (2) of subjective symptoms, and (3) of objective manifestations. (1) Quiescence may continue in many instances for a considerable period after caries has reached the pulp where the situation is such that the force of mastication cannot cause compression of the contents of the cavity. Notwithstanding constant saturation of the gelatinous covering, and the presence of the micrococci concerned in producing the caries of the dentin, excitement of the pulp may not occur. The fact should not be overlooked that some persons escape odontalgic 300 CONSERVATIVE TREATMENT OF THE PULP. symptoms notwithstanding such progressive alteration of the pulp tissue takes place as to result in gangrene of the organ. (2) Usually, however, after a period of quiescence of a longer or shorter duration there arises a train of subjective disturl^ances brought on by the continuance of chemical irritation and by the presence of fluids in the cavity, these influences becoming accelerated as the area of exposure becomes increased. The pain which occurs in this stage is reflected to one or more branches of the fifth pair of nerves. Flashes of pain occur to the teeth of the other maxilla, to the eye, or the supraorbital region, the most common region affected being the nerves of the ear, pain in this organ being probably the most general form of reflection which occurs. The exacerbations take place usually in the evening and at first entirely remit in the daytime. The pain in this stage will fre- quently pass away as the pulp is relieved from pressure and chemical irritation. In this stage the surface of the pulp does not present indications of being inflamed. From the lack of continuity of the symptoms it is a reasonable inference that the hyperesthesia observed in this condition is due to impressions made upon the point of encroachment and is con- fined to the nerve fibrils distributed about the capillary loops involved, and thereby induces the reflected manifestations, the nerve fibrils being in this stage the anatomical element chiefly implicated. (3) Objective symptoms comprise those manifestations which after the subjective ones have continued for some time become localized in and about the affected tooth. These are — some soreness of the peridental membrane ; sensitiveness to heat, accompanied throughout with heavy pain in the tooth, and at length pulsative throbs. Tills order of statement is the usual sequence in which these indica- tions appear. They are the result of the extension of the disturbance to the deeper circulatory elements of the tissue. When this condition appears on the presentation of a case, or Avhen in the course of the treatment it becomes apparent, the prognosis usually is rendered unfavorable to recuperation. The Technical Treatment op the Uncovered Pulp. Accidental Exposures. — These, which happen in the preparation of cavities, if produced Ijy clean (aseptic) instruments where compres- sion has been avoided, require but simple treatment. The pain is relieved by the application of tincture of calendula one part, to four of water. When the bleeding ceases, the point of exj)Osure should be antiseptically dressed and capped in the manner to be described. If the injury has been slight, the cavity may l)e at once filled with a metal, having regard to the strengtli, the placeuient, and the fixation THE TECHNICAL TREATMENT OF THE UNCOVERED PULP. 301 of the cap used to defend the part from compression. Here the fixa- tion may be made by covering the cap with a broad block of gold foil ; after adapting this to the margins of the pulp wall of the cavity the filling may be proceeded with. In case of doubt a metal of less con- ductivity may be used, such as tin or amalgam. A metal filling is better in these cases, since the slight thermal irritation tends to the ultimate recovery. (See Chapter V., p. 131.) Treatment of Recent Exposures. — When the pulp has been fully uncovered, as previously described, the cavity should be washed clean with tepid water, be securely protected from the fluids of the mouth with rubber dam, dried, and lightly filled with a pledget of lint sat- urated with a mild disinfectant. On account of the invasion of the zone of dentin immediately beneath the caries by bacteria and micro- cocci, it is recognized that some means of sterilization must be adopted. This being necessary in the treatment of ordinary cavities, it is evidently here more demanded. On account of the impatience of the pulp to medication it is important to be careful in the selection of the sterilizing agent. The choice should be between hydronaphthol, acetanilid, and formalin : the first in the strength of 1 to 300 parts water ; the second, 1 to 200 parts ; the third, not stronger than 3 per cent. The saturated pledget of cotton may remain in the cavity during the procedures of the preparation of the dressing paste, the selection of the cap, etc. When these preparations are complete the cavity should be again dried, the drying being finished by a few pufPs of warmed air. The point of exposure and the adjacent dentin are now touched with lint, filled with carbolic acid and oil of cloves, equal parts. The effect of this is to coagulate to a superficial degree the point of exposure. This practice is largely empirical. It may be avoided in cases where no disturbance has previously existed ; but where there are evidences of irritation it is indispensable. The application of carbolic acid in this manner should be for a moment only. As carbolic acid has a very feeble affinity for water and as the topical touch is but momentary, it probably does not invade the tissue to an appreciable degree. It will also be observed that the com- bination possesses anesthetic properties. The student will not fail to hold in vicAV that the treatment is appli- cable to cases in which it is evident the pulp tissue is not under much irritation. The condition should be one of hyperemia of the organ and gives indications of this by the existing hyperesthesia. Congestion should not have taken place, neither should inflammatory indications exist. Therefore the inference is that after the soft caries is removed the surface of the dentin and the point of exposure may be sterilized 302 CONSEEVATIVE TEEATMEST OF THE PULP. and the vital force of the pulp be given the opportunity to overcome whatever slight bacterial invasion may have reached that organ. Here the case must rest npon the well-established fact that the tissues have considerable power of mastering the inflnence of non-pathogenic germs as a factor in the process of recuperation. Treatment of Old Exposures. — In the conditions which exist where denndation has taken place to a considerable degree and where irritation has long continued, the disturbances Avhich have arisen in consequence of the extension of the disorder to the large blood-vessels and the attendant alteration of most of the anatomical elements of the pnlp, the chances of establishing quiescence are slight. In the earliest stages of objective disturbances when the constitu- tional conditions are favorable an attempt may be made at conservative treatment after the inflammatory conditions are subdued by antiseptic treatment, accompanied l)y the use of resorbents and counter-irritation upon the gum. Capping the Pulp. A prominent feature in the conservative treatment of the pulp is the means to protect it from pressure, in agreement with the established fact that there is no irritation so fatal to the normal functions of the pul]) as compression, and no condition from which it recovers with so much difficulty as this. Therefore all means directed toward its con- servation must conform to the necessity of preventing the least degree of compression. The means employed to prevent this form of disturb- ance have given this method of treatment the common appellation of " capping the pulp." Another principle of equal importance connected with the foregoing is that the capping material sliould be l)rought into immediate apposi- tion with the pulp. This is for the reason that if the least space be permitted to exist between the capping and the exposed point this space will fill with effused fluids, and the putrefactive changes taking place in these fluids induce the formation of gases which produce compression. METHODS OF CAPPING. Various methods of capping are practised, such as laying on the part disks of paper or asbestos rendered antiseptic in various ways : Using of disks of paper coated on the side to be placed next the pulp with " chloro-percha " or other plastic matter ; flowing over the exposed point a coating of oxysulfate or oxychlorid of zinc, being careful with the latter to use a formula of the fluid element in which the zinc chlorid is only in sufficient proportion in relation with the water that the union with the zinc oxid is not active. In connection with this method it has been common to mistakenly employ the strength of the CAPPING THE PULP. 30a fluid which is used when the formula is adapted for temporary fillings. When this method is used the coating is flowed over or laid in a cap on the pulp, and when somewhat "set" the cavity is temporarily filled with a more resistant material laid upon it with great care. An objection to this method is that it is not applicable to small cavities unless the paste is contained in the concavity of a metal cap. The results are salutary with the cautions here outlined. With all the precautions which may be taken these described dress- ings are somewhat complicated and not applicable to small cavities or those difficult of access. In these cases the writer has generally depended upon the use Fig. 298. of a dressinp; comijosecl of carbolic acid and .^^^ ,^», -^ ft ^ i^ ,^ ^^ f ^ 1 ^ 1 ■ 1 vu ■ Q) © O i i B O oil 01 cloves equal parts combmed with zinc ^0 '^^ ^^^ m w ^ Oxid to form a plastic paste of such consist- westons dental cavity caps. ence that when it is laid upon the pulp it will yield, as it is adapted to the part, without producing pressure, and will flow out around the margins of the metal cap when this is used to convey the dressing. The composition of the dressing is based upon the considerations that the menstruum is antiseptic, and possesses some anesthetic value. It also remains unchanged within the space and in time becomes, from the dissipation of the menstruum, somewhat firm in its character. The therapeutic action of the menstruum when combined with the zinc oxid is mild, and is employed for the reason that it is slowly given up by the oxid, and therefore makes an acceptable dressing. The Cap. — In all cases it is essential to use a metal cap. The methods where this is used are simpler and l^etter under control than when dressings are made without this appliance. The reason for this is that the avoidance of compression is more certain. The caps are best when made of platinum, for the reason that it is a resistant material and is of convenient formation. When the outer filling is to be of gutta-percha or of the mineral cements, caps may be formed of concave disks of pure tin. These and the platinum caps are stamped from the plate by the hollow punches of the hardware shops, by which means various sizes of round and elliptical ones may be formed. The effect of punching them upon the end of a block of wood gives the suitable concavity to meet the require- ments. For ordinary purposes they should be quite thin, but when gold fillings are made over them the thickness and the concavity should be such as to enable them to sustain the force applied. In cases where there are indications of approaching congestion, or where it is probable that the exposure is not recent, the dressing should have added to it a portion of guaiacocain. 304 CONSERVATIVE TREATMENT OF THE PULP. Fjg Placing the Cap in Position. — Placing the cap in position is a step in the treatment requiring care. It should be assured that it is of suf- ficient size to pass well beyond the borders of the ex- posed organ, and in the approxinial cavities it should cover the pulp Mall of the cavity without intruding upon the marginal ^valls. If there is a single exposure it should be round ; if two cornua are exposed, either two caps should be laid or one oval one employed, as may best suit the case. In molars, usually, where two j)oints are exposed, two caps are generally best; in the bicuspid, one oval one under the same circumstances. The cap should be inserted edgewise in such manner that as it is laid in place the excess of dressing may flow out at the margin toward the operator. This is to prevent undue pressure, and to avoid air being included beneath the dressing, which would prevent complete apposition of the dressing with the pulp. In cases of easy access the cap may be laid in place with fine-pointed pliers — notable the Bogue pliers ; but in the majority of instances it is preferable to previously coat the convex side of the metal Avith yellow wax, when, with an instrument adapted to the case, it may l)e carried into position and then placed in the manner described. It should next- be pressed into position with sufficient force to bring the margins in contact with the dentin. Any excess of dressing should be taken away by light touches of an excavator, and when the cavity is to be filled temporarily it is better to fix the cap in place by flowing over it a little chloro-percha, which, when dried, prevents disturbance of its position in the filling procedure. Care should be taken that when the pulp is found exposed in a de- pression, as occtirs sometimes in the molars, this depression should be filled nearly or quite to a level with the floor of the cavity by taking a little of the dressing upon a suitable instrument and carefully filling this point ; otherwise, when the cap is placed, the paste may not find its way into contact with the pulp. At the moment of placing the cap, as the ])aste is yielding under the gentle pressure of forcing the edges of the caj) into contact Avith the dentin, a little pain Avill sometimes be observed ; but unless the paste is too stiff no compression of the pulp should be caused. Pilling the Cavity. — "Whether the cavity shall be filled temp(jrarily or permanently depends upon the prognosis. This, as will be perceived, is based U])on the constitutional conditions and the state of the pulp at the time of treatment. Fig. 300. Cap in position. CAPPING THE PULP. 305 For those of small experience in this line of treatment it would not be safe to attempt the permanent stopping of the cavity, except in acci- dental exposures and in cases where the history of no previous disturbance can be elicited. Even in the latter class it is generally best to delay permanent closure by a conductor of heat until after an experience of a year or more with a non-conducting stopping. At the end of this time the filling may be nearly all removed, care being taken not to disturb the cap, when, with suitable precaution, a metallic filling may be inserted. In the majority of instances it is safest to fill the cervical part with gutta-percha stopping, carrying the material over the cap, and then to complete the filling with zinc phosphate. In this way, with an occa- sional renewal of this temporary work, cases may be carried forward from ten to fifteen years. They may, however, be closed permanently and safely after an experimental trial of five years where no irritation has appeared. In many instances recovery takes place by secondary deposits of dentinal tissue the exact character of which has not been made out. The writer has observed a multitude of cases in practice when the open- ing at the point of exposure has become occluded by bony tissue. In some instances this has occurred in two years, in others after longer periods. In one instance a lateral incisor became protected by this formation, but in consequence of mistaken diagnosis of another condi- tion causing pericementitis. A drill was passed through the new tissue to the living pulp and this new opening healed. In the same mouth another incisor also recuperated in the same manner. In some cases when entire quiescence has been maintained for many years the pulp will be found not to have undergone any protective changes. It is not remarkable, however, that pul[>s may remain in a state of quiescence for a long period, when it is considered tliat in slowly- advancing caries the pulp will often be exposed for a long time without the occurrence of any signs of irritation, unless, by the position of the mouth of the cavity, the pulp has been subjected to the pressure of food. It may be concluded that, whether the pulp becomes protected by secondary deposits or acquires complete quiescence, conservative treat- ment in these cases has considerable advantage over immediate devital- ization. Still, in this connection in order to avoid embarrassments the necessity exists for careful selection of subjects to be treated in this manner, and also for proper analysis of the apparent condition of the pulp itself. To aid in this discrimination the following summary of conditions should be held in mind : 20 306 CONSERVATIVE TREATMENT OF THE PULP. (a) Where no previous observable disturbances can be elicited. (6) Where the tooth has been impressed only by the application of low temperature. (e) Where, in addition, reflected pain in related parts has been observed. ((/) Where the tooth has become subject to impressions by heat. (e) Where continued objective disturbances appear, such as soreness to touch, or local pain of spontaneous character accompanied by pulsa- tion. Classes a, b, and e may be considered as amenable to treatment, and also, problematically, class d if taken early. Class e must, in view of the principles stated in this section, be eliminated from the held of con- servative treatment ; and where cases in the other divisions apparently amenable subsequently take on disorders coming within this classi- fication they usually have passed beyond the reach of palliative treat- ment. It is important here to consider the influence of the physical endow- ments of the patient upon the conservative treatment of the pulp. For some persons this treatment is followed by the happiest results ; no impatience of the operation appearing, and even cases somewhat un- promising doing well. Again, with others, any case, however simple, goes down the scale to class e in spite of every care. The first constitutional condition favorable to success is that of soundness. As to what are called temperamental indications, when the subject is of good health, the lymphatic should alone be excluded and more particularly the bilio-lymphatic. These latter do not respond to pulp treatment in any conditions which occur to them ; and in reference to their exposed pulps the probabilities are that in the sluggish condi- tion of the parts involved the organ is early invaded by bacteria, and such changes have quickly taken place in the anatomical elements of the pul}) as to render all chances of successful treatment valueless. The most promising cases are those for persons of active temperaments, with good circulation, thin skins, healthy gums, and limpid oral secretions. After-treatment. — It is not unusual for classes «, b, and c to require after-treatment. For this reason close observation for some time should be maintained. It is presumed that the judicious operator has made careful selection of the cases to be conservatively treated and that he will early decide from an analysis of the evident conditions whetlier the prognosis is promising or not. As previously indicated, some of the apparently favorable cases will not yield to treatment for the reason that the actual condition of the pulp cannot be made out. Part of the difficulty here is occasioned by the indefinite ('hara(!ter of the statements of the patient, who should id all cases be instructed to return for con- CAPPING THE PULP. 307 sultation if impatience of cold appears or if reflected pain should occur. If these conditions supervene it is a sign of needed care to avert in- creasing: disturbance. A most marked form of reflected pain is felt in the ear, and this frequently occurs previous to the aggravation of the temperature sense. So much importance should be attached to this symptom of pulp dis- turbance that the first question asked a patient appearing with pain, or on approaching a suspected pulp, is, Have you had any pain in the ear of that side? As reflection to the ear often occurs long in advance of similar pain in other branches of the fifth pair, it becomes important to maintain close observation of this indication. In this state, sedation combined with counter-irritation is required. In any case where the tooth has been impressed by cold, either before the treatment or afterward, an application should be made to the gum over the tooth, of tincture of aconite root two parts, chloroform one part. The mode of application is important. A pledget of cotton or muslin to cover an area of one-half by three-fourths of an inch should be filled with the prescription, then squeezed out nearly to dryness between folds of a napkin to prevent an excess flowing over the mouth and with the saliva entering the fauces, to which it is extremely irritating as well as unnecessarily medicating the patient. Before the pledget is applied the surface of the gum should be cleansed of the coat of mucus cover- ing it, otherwise the remedy will fail to come in contact with the mem- brane. It is equally important that dryness of the surface be secured. This application should be maintained for from twelve to fifteen seconds. If allowed to remain too long upon the part, vesication takes place. The general after-treatment consists in the repeated application of aco- nitum, the repetitions not being made at the same point more frequently than at intervals of forty-eight hours. When it is desired to increase the counter-irritation, the gum may be scarified very superficially by quick, light movement of a small scalpel. The patient should be in- structed to avoid subjecting the tooth to extremes of temperature in either direction. The control period of conservatively treated cases is usually within the first fortnight after the capping. It sometimes becomes necessary to open the cases and recap. This usually occurs when in reviewing the case it is considered that some oversight has occurred. There may have been two exposures. The cap may not have completely covered the exposed part. There may have been some compression from forcing the cap. It may have been displaced during the after procedures. The case may be determined to go down the scale of irritation, and in despair we sterilize again and make another trial. The most careful records of cases should be kept, with a relation of 308 COySERVATIVE TREATMENT OF THE PULP. the condition and of the controlling- symptom?;. These records should be methodically preserved in a book ke})t for this purpose. Should sub- sequent irritation occur, a new diagnosis may be formed from the recorded facts and the new conditions. The record of conservatively treated pulps should be carried forward to the examination chart at each recurring periodic examination of the teeth. It is better that they be marked in symbol with red ink, to prevent the unnecessary removal of temporary fillings and to explain the reason for their presence and thus avoid the accident of an unnecessary uncovering of the pulp in such cases. Calcific Changes in the Pulp as related to the Operation OF Pulp Capping. When loss of suljstance takes place slowly, either by carious action or by attrition, a notable calcific gro^vth takes place in the ])ulp cham- ber opposite to the point of waste in the direction of the radiant course Fk;. 301. Secondary dentin, resulting from irritation of the dentinal fibrils by caries (Blaekl A, Diagram of an incisor having a decay in the labial snrface, a, and a deposit of secondary dentin at h. The point from which the illustration B is taken is shown by c B, Illustration of the tissue of the secondary deposit in A : a, primary dentin ; h, secondary dentin; c, seems to be a blood- vessel that has become calcified ; f/, an irregular fault having some resemblance to the lacunse of bone : e, pulp chamber. It will be noted that there are irregular deposits of granular matter in the substance of the secondary dentin, and that the tul>nles wind about tlieni. of the tubules (see Fig. 301V If the lo.ss of substance from the ex- terior progre.s.ses with sufficient slowness encroachment uj)on the pulp does not take place. The pulp chamber may become obliterated by the progressive deposition of calcific matter, whicli has the designation of secondary dentin. The morphologicid character of the secondary de])osit is histologically irregular, being fre(|uently of mixed character, presenting some of the CALCIFIC CHANGES IN THE PULP. \m characteristics of dentin and also containing cemental cells with radiant and anastomosing canaliculi. For this reason deposits have been desio-nated as osteo-dentin. In the earlier years of life opportunity does not ofter to study these changes of structure, as the usual progress of caries is too rapid, ]jut in advanced life they are common, it being not infrequent to find complete obliteration of the pulp cavity as well as of the canal of the root (see Fig. 302). In some instances nodules of calcific material appear un- FiG. 302. i^h Calcification of the dental pulp (Black). At A is shown the outline of a lower molar with a cavity at 6. The pulp chamber is much reduced in size and filled with calcific material, as shown in B. a, a large granular mass of calcific material, which is very transparent but finely granular. A very few irregular lines are seen in the centre, which slightly resemble dentinal tubes ; h, an erratic growth of irregularly formed and unusually transparent dentin ; c, line of the growth of dentin from the floor of the pulp chamber : the growth from other directions is so perfectly regular as to leave no markings; d, margin of the cavity of decay; e, a bundle of cylindrical forms of calcific material extending down into the root canal. These extended to the apex of the root. attached to the walls of the pidp cavity (Fig. 303). These increase sometimes by external development and in other cases hy the coalescence of several contiguous nodules. Again, several nodules iidiabiting the pulp chamber may increase in size without becoming fused, and, accom- modating themselves to each other as development progresses, they at length completely fill the cavity, from which they are severally removed with great difficulty. It is remarkable that while in some instances pulp nodules become the cause of producing violent pain by their pressure upon the nerves of the pulp, in the majority of cases substitution of the normal tissue 310 COySERVATIVE TREATMENT OF THE PULP. takes place until nearly complete occlusion of the }>ulp cavity is affected without the occurrence of pain. Small pulp nodules are not infrequently found in pulps otherwise perfectly normal, but generally they are evidence of continued irritation Fig. 3Uo. A, Outline of a lower molar, with a large carious cavity at a : b, pulp-chamber. The shaded por- tion, c, was occupied by cylindrical calcifications. B, Illustration of the cylindrical calcifica- tions. X 100. (Black.) of a mild form usually attending the progressive slow advancement of caries of the tooth. But this is not necessarily the case, since some of the most violent attacks of dental neuralgia have arisen from the pres- ence of nodules in perfectly sound teeth. The diagnosis of the existence of pulp nodules as the cause of pulp irritation is not easily made out. The determination of the condition usually can be reached only by the process of exclusion. As they do not occur early in life while the teeth are undergoing ordinary develop- ment, they may be looked for only after middle life. The pain is dull and reflected, and the paroxysms are frequent. There is sensibility to cold, and rarely pain appears on percussion. When the teeth are sound, the disturbing one will usually be determined by the tem- perature tests. An important differentiation from the usual irritation of ordinary pulp disturbance from exposure or the thermal irritation caused liy the approximation to the pulp of large metal fillings, is that the disturbance from nodular irritation is not rapidly progressive and that the irritation may continue without marked exacerbations or subsidence for consider- able periods. Treatment is useless which does not include drilling to the pulji and devitalizing it. The difficulties involved in treatment by devitalization are liable to be attended by great pain, since when the pulp chaml^er is much occupied by nodules the action of the devitalizing agent has not free course. In these ca.ses the remains of the pulj) between the nodules CALCIFIC CHANGES IN THE PULP. 311 and the walls of the chamber are attenuated, and when irritated by the arsenous acid give expression to an excessive degree of pain.^ The Influence of Pulp Exposure, and the Effect of Conservative Treat- ment of the Pulp upon Calcific Dejjositions. — Allusion has been made to calcific deposits occurring on the walls of the pulp chamber as the result of peripheral irritation. Here, as stated, these accretions only occur when the degree of irritation is slight and of long continuance. The examples of this which have been given in dental literature are conclusive as to the ability of the pulp at all stages of its existence to take on this action when the conditions are as stated. On the contrary, when the disturbances are active the formation of calcific deposits on the walls of the pulp chamber do not take place, or if in the earlier progress of decay they have commenced, as the progress of the destruc- tive action approaches the pulp this change is suspended and in some instances resorption of the secondary deposit takes place. It is apparently in this manner that the pulp becomes denuded under the influence of thermal or traumatic irritation in cases in which there Avas no evidence of exposure at the time of the preparation and filling of the cavity. This result would appear to be related to the principle that secondary structures and tissue of repair are liable to resorption as the result of irritation or disturbances of nutrition. The frequent occurrence of secondary dentin following the conserva- tive treatment of the pulp and in some instances occurring spontaneously over exposed pulps, raises important considerations connected with the subject. The Avriter has had many instances come under his observation in which secondary dentin has obliterated exposures, both in his own cases and in those of others. The influence of the tendency to nodular deposits upon the results of conservative treatment does not appear to be detrimental unless the pulp chamber becomes largely filled with them. The pulp at the period of life when calcific deposits usually take place is not so sensitive as it is at an earlier age, and therefore, unless senile conditions appear to be present or imminent,' the existence of such deposits should not be inim- ical to the preservation of the pulp. The writer, who has had frequent cases of pulp devitalization after conservative treatment, has rarely ob- served " pulp stones " in these cases. It is an important consideration that when calcific deposits take place beneath fillings where the pulp has been nearly exposed, or where they have followed conservative treatment of the pulp, they are liable to resorption on the occurrence of irritation of the pulp from any cause which brings on an increased blood supply. This is more remarkable since there are no lymphatic vessels in the pulp. This change can occur ^ For the form and extent of nodular calcification see American System of Dentistry. 312 CONSERVATIVE TREATMENT OF THE PULP. onlv l)v the development of osteoclasts on the surface of the pulp. Of this development there have been several recorded instances where the dentin has suifered resorption until the enamel has been encroached upon bv the process of denudation, and when favorable conditions Mere established a deposition or formation of secondary dentin has occurred. Devitalization and Extirpation of the Dental Pulp. When the existing conditions are such as to require the devitalization of the pulp there are several requirements essential to secure a satis- factory result : (1) That little pain be inflicted. (2) That the destrnction be quickly effected. (3) That precaution be taken to prevent discoloration of the dentin. The first requirement is the most important, since, if the means used to effect the devitalization are painless or nearly so, the pulp promptly yields to the devitalizing agent and there is little danger of discoloration of the dentin. At present there are three general methods of procedure : by chemi- cal means, by extirpation with suitable instruments, and by narcotization of the tissue. Reliance has usually been placed upon chemical agents, these being — 1. Zinc chlorid ; 2. Caustic potassa ; 3. Chromic acid ; 4. Arsenous acid ; 5. Arsenical ore (cobalt). The agents 1, 2, 3 are usually painful, of slow progress, difficult of application, and uncertain. Hence arsenous acid has usually been depended on. This substance, notwithstanding certain objections, is the most available and most reliable of the substances above named. It has generally Ix-en combined with acetate of morphin in variable pro- portions, to which has been added in the formation of this paste a suf- ficient quantity of creosote, carbolic acid, or one of the essential oils, to give the combination the consistence of cream. ^ In making this formula it is important that the ingredients be thoroughly ground together to effect the comminution of the arsenic and the morphin as well as to intimately mix the components. The m(»rpliin is used as a sedative to counteract the excessive irritation fre- quently caused l)y tlie action of the arsenous acid, which is also modified by the anesthetic influence of the creosote. Carbolic acid has been fre- ' Of late cocain has largely superseded the morphin salt as an ingredient uf these pre- scriptions. As — R Acid, arsenosi, Cocainx' hydrochl., cm. 01. cinnamomi, q. s. M. et ft. pa.ste. DEVITALIZATION AND EXTIRPATION OF THE PULP. 313 qiiently substituted for creosote as being of less disagreeable odor, and as, from its coagulative action upon the surface of the pulp, it prepares the tissue to absorb the arsenic and markedly lessens the time of absorp- tion. It is a well-known fact that with great frequency the application of arsenous acid to the pulp is so greatly irritating to it that much pain is excited, which brings about congestion of the surface of the pulp to such a degree as to delay absorption of this agent. When the above-stated combination is applied to a living pulp which has not been in a state of disturbance, and therefore is in the condition of quiescence considered in the section on conservative treatment of the 2)ulp, little or no excitement of the organ takes place. If the paste be carefully applied in such a manner as to avoid pressure the pulp does not usually become excited and promptly succumbs to the chemical force of the arsenic. When on the contrary the pulp is in a condition of active congestion, such as is presented by long exposures, and where congestion has supervened as the consequence of futile attempts at con- servation, the danger of violent further excitement of the pulp is nearly certain. In this condition the pulp resists the absorption of the arsenic and repeated applications are liable to produce no better results. The failure to discriminate the different conditions of the pulp accounts largely for the variation in the action of the same formula upon the exposed pulp. , It becomes important, therefore, to reduce the state of hyperesthesia of the pulp and to relieve the congestion in many instances before commencing the devitalization. The relief of congestion requires, first, the disinfection of the surface of the pulp and of the dentin contiguous to it. The most efficient agent for this purpose, generally, is formalin, which after the first slight pain produced by it is almost immediately soothing. Formalin owes its value as a disinfectant to its extreme diifusibilityand in the strength applicable does not appear to be coagulative in its action. The strength should for this purpose not be greater than 5 per cent. As formalin is composed of 40 volumes of formaldehyde with 60 of water, the above- stated percentage is produced by adding 1 volume of formalin to 7 volumes of water. Iodoform has been much used in combination with arsenous acid in the devitalization of the pulp ; its value depends upon its disinfecting power, but this frequently fails to prevent the arsenical irritation when the two drugs are mixed together, in cases which are in a state of con- gestion, for the reasons given above. When violent congestion is manifest and when the pain attending the removal of the carious matter forbids the complete baring of the pulp, a paste composed of tannic acid and oil of cassia sealed in the 314 COXSERVATIVE TREATMENT OF THE PULP. cavity will so far subdue the conditions as to permit complete removal of the caries. This application should be allowed to remain for several days. For the relief of ordinary congestion of the pulp cocain offers the best means, since it has direct and positive action over the capillaries, which has generally been adduced to account in part for its anesthetic influence, as by lessening the supply of blood in the capillaries it there- bv reduces the stimulation of the nerve fibrils. In eases of known con- gestion as determined by the symptomatology when there is no effusion of lymph or pus from the exposed surfoce, the pulp is bathed with a strong solution of cocain and is then covered with a deep cap filled with a paste of cocain and oil of cinnamon hermetically sealed in for several days, when usually the arsenical paste may be used with much-lessened danger of irritation. In these cases, and indeed in all cases, an excellent formula for de- vitalization will be found in the combination of 10 grams of arse nous acid ground well with 20 grams of cocain. This is taken upon a minute pledget of cotton previously charged with oil of cinnamon, which is laid upon the exposed point and then sealed in hermetically, care being taken to avoid compression l)y arching over the dressing a suitable cap, or bv flowing over the dressing a paste of one of the mineral cements. When there is evidence of the exudation of pus, this is checked by the application of deliquescent zinc chlorid or by washing with pyrozone. Usually in such cases the surface of the pulp has become necrotic by the suppurative process and will not be so repel la nt of the arsenic as in ordinary cases. The time usually required for the action of the arsenic to reach well toward the apex of the roots is from four to six days. This, however, depends upon the quantity of the preparation applied and the resistance of the ])ulp tissue. As the aim should be to procure the nearly com- plete death of the ])ulp by one application, the longer period is preferable as entailing less difficulty and the expenditure of less time than when sli Micro-organisms found in cultures from a gangrenous pulp. the smaller cocci and diplococci (5) nearest the apex of the root (c. Fig. 304, 1 ) where suppuration was in progress ; the larger forms and more varieties were found in the necrosed and decomposing portions of the ' Miller, Dental Cosmos, .July, 1894. PATHOLOGICAL CONDITIONS. 319 pulp (4, 3, 2), The cases of gangrenous pulps exhibit a mixed infec- tion, several varieties of cocci, bacilli, and spirochsetes being found/ Cases are occasionally seen in which the pulp of a non-carious tooth has been devitalized in consequence of a blow, injuring the vessels as they enter the apex of the root ; the same effect is not rare as a conse- quence of too rapid or extensive movement of teeth in regulating. The pulps in such cases are probably destroyed by thrombosis of the vessels at the root apex. The death of the pulp may not be detected for years ; when evidences of albuminous decomposition are discovered, a growing opacity and changing color of the tooth may be detected. In other cases alveolar abscesses may form and discharge at some point near the tooth, or it may be at some distance from it. It is presumed, that the organisms which have effected this decomposition of the pulp resulting in the suppurative process have found their way to it via the blood current. It is within the experience of every dentist that the products of decomposition occurring under these conditions afford a suitable soil for the development of virulent micro-organisms as soon as the tooth is opened to the air. The several conditions described are to be regarded, for purposes of treatment, as definite pathological states. The treatment is to be directed to the attaining of such conditions as shall ensure the retention of the tooth with an entire absence of pathological manifestations. Rational therapeutics should govern each procedure. Cases in ivhich the Pulp has been Intentionally Destroyed and Re- moved en masse. — As this procedure usually has been determined upon in consequence of suppuration or inflammation of the pulp, the septic organisms, the staphylococci, streptococci, and bacilli, have followed the course of the inflammation, i. e. along the veins. The organisms of putrefaction, if present, have affected but in very limited degree the most external portions of the pulp, so that the color of the dentin is unaltered except to a very slight depth. After the removal of the pulp the contents of the tubules are chemically unchanged, and the canals contain no organic matter, except the blood which may have escaped in consequence of tearing away the pulp. There may also remain odonto- blasts which have become mechanically detached during the operation. Provided no organisms have been introduced during or subsequent to the operation of extirpation, the canals are aseptic. If proper anti- septic precautions have been taken, sterilizing and isolating the tooth to be operated on and also the instruments employed, no infection occurs. These are the cases in which immediate root filling has been recom- mended and practised with success. 1 See Fig. 304. 320 THE TREATMEST AND ETLLTSG OF ROOT CAXALS. Fig. 305. Pignieut. S — ha?moglobin. COo.XHa; H«0 and HoS If the septic process has invaded the pulp extensively the pnlp tissue, as its destruction progresses, be- comes the seat and soil of putrefactive decomposition involving also to a vari- able extent the contents of the dentinal tubules, and the color of the dentin un- dergoes a series of changes.' The ap- pended figure (Fig. 305) gives a graphic diagrammatic representation of the serial decomposition of an infected pulp. The albuminous constituents of the pulp un- dergo fatty transformation ; next putre- factive decomposition attended by the evolution of hydrogen sulfid, ammonia, and other end products. According to the romatic and Gxtcut of invasion and its variety, waste fatty prod- products are formed (ptomains and al- lied substances) by the organisms which act as irritants to the vital tissues, until, when the apical l)ut still vital portions of the pulp become the soil for the de- velopment of pyogenic organisms, the tissues of the apical space are affected. Usually in the later stages of pulp sup- puration the tooth becomes sensitive upon percussion. Succeeding this state of aflPairs is a period of delusive quiet, during which the apical tissues, although doubtless affected by the toxic substances present, exhibit 1)ut slight subjective symptoms. The remnants of the pulp are undergoing progressive decomposition, as are also the contents of the ad. q.s. to make stiii paste. — M. Ol. cassiae, j ^ ^ ** A tannate of mercury is formed ; it is insoluble, and but little pain is caused by its absorption." It is to be understood that these preparations and this method of pulp preservation are only to be utilized when reasons exist which would preclude the perfect cleansing and filling of canals. These , reasons may be economic, or, the impracticability of thoroughly extir- pating all pulp remnants. Failing in perfect extirpation, the paste is to be packed into parts where the irremovable pulp remnants exist. Topographical Anatomy of the Pulp Chambers and Canals. A familiarity with the topographical anatomy of pulp chambers and canals is an essential preliminary to their proper opening and cleansing. Figs. 308, 309, and 310 (see pp. 331-333) illustrate the average pulp- chamber forms. The following outline figures (Figs. 311-346) are exact reproductions of sections made of typical teeth which have been shown by comparison with numerous other sections to be about the average anatomical forms. The Upper Central Inckov. — The pulp chamber (Fig. 311) approxi- mates in form that of the tooth itself. The opening of the canal is seen to be almost circular, and in the central axis of the tooth. Upper Lateral Incisor. — The chamber of the lateral incisor (Fig. 312) Fig. 312. s Upper central incisor. Upper lateral incisor. has a similar form ; the canal exhibits a tendency to diverge from the straight line toward the a})ieal end (see Figs. 313, 314, 315). The en- trance to the canal is nearly oval. FORMS OF PULP CHAMBERS AND CANALS. 335 Upper Cuspid. — The chamber of the upper cuspid is large and open and has an elliptical canal entrance (Fig. 316). The root of this tooth Fig. 313. Fig. 314. Fig. 315. Upper lateral incisors (Ottolengui). may also deflect from the line of the general axis. In rare cases a bifurcation of the root is seen (Figs. 317, 318). Fig. 316. Fig. 317. Fig. 318. Upper cuspids. The upper first bicuspid very commonly exhibits a bifurcation of the roots which may extend to any distance toward the crown (Fig. 319). At its entrance the pulp canal has a dumb-bell form, the handle of the dumb-bell being much attenuated. The distinct canals may begin almost at the base of the chamber, or be evident only near the apices of the roots. Tw^o distinct canals may be present even in the absence of bifurcation of the root. The roots of this tooth may be much curved. Fig. 320. Fig. 321. Upper first bicuspids. Fig. 320 presents a condition occasionally seen : a trifurcation of the root of a bicuspid. Fig. 321 represents a section through the buccal 336 THE TREATMENT AND FILLING OF ROOT CANALS. roots ; Fig. 321 also shows the neck section of the tooth. In the same mouth were found three bicuspids exhibiting the same condition. The bifurcated cuspid, Fig. 318, was from the same denture. Upper Second Bicuspid. — Sections of two typical forms of upper second bicuspid are shown in Fig. 322, a and b. In such a case as b — far from uncommon — it will readily be seen what dangers exist as to difficulty of perfectly filling the flat general canal beyond the ellip- tical obstruction. The neck section in both types is almost alike. Upper First Molar. — The neck section of the upper first molar Fio. 322. Fig. 323. Upper seccmd bicuspid. Upper first molar. (Fig. 323, a) shows a free entrance to the palatal root ; the anterior buccal root has a triangular entrance, near the mesio-buccal angle of the tooth. The entrance to the disto-buccal root is very small ; 6, Fig. 323, shows a section through the buccal roots of the tooth. Cases are occasionally seen where a short crown is associated with very long and divergent roots (Fig. 324). Fk;. 324. Fig. 325. Fig. 326. Upper molar. Upper second molars. Upper Second 3Iolar. — The arrangement of canals in the second upper molar (Fig. 325, a) is much like that in the first ; except that the tooth has a compressed form which brings the canal entrances closer together. A section through the buccal roots is seen in Fig. 325, b. This tooth occasionally presents marked aberrations in the location and distribution of pul]) canals. Fig. 326 illustrates a case in which there was a trifurcation of the palatal root. Other abnormalities of the canals FORMS OF PULP CHAMBERS AND CANALS 337 of upper molars are shown in Figs. 327, 328, 329, 330, 331, and 332 (Ottolengui ^). Fig. 327. Fig. 328. Fig. 329. Fig. 330. Fig. 331. Fig. 332. Upper molars (Ottolengui). Upper Third Molar. — The three roots of the upper third molar are frequently compressed together, giving the external appearance of a Fig. 333. Upper third molars. single round conical root. In many instances there will be found but a single large canal, as in Fig. 333, a. The rule is three canals, as Fig. 334. Fig. 3.35. Fig. 336. Lower incisors and cuspid. shown in Fig. 333, b, which shows also a section through the buccal roots. The root is generally curved backward more or less. , ' Methods of Filling the Teeth. 22 338 THE TREATMENT AND FILLING OF ROOT CANALS. Lower Anterior Teeth. — The forms of the canals and canal entrances to the lower anterior teeth are shown in Figs. 334, 335, and 336. The form of partial canal bifurcation shown in Figs. 335 and 336 was noted frequently in longitudinal sections of typical teeth. Loioer Bicuspids. — The forms of the canals in the lower bicuspids are much alike ; the canal of the first, however, exhibits a tendency to the dumb-bell form of entrance (Figs. 337, 338). Tortuosities of the Fig. 337. Fig. 338. Lower first bicuspid. Lower second bicuspid. canal are far from uncommon, many of them of such nature as to ren- der full and complete entrance to their ends next to impossible ; in Fig. 339. Fig. 340. Fig. 341. Lower bicuspids. Fig. 339 the root was of corkscrew form, in Fig. 340 bent at right angles, and in Fig. 341 a short crown is associated with an extremely long and bent root. Fig. 342. Lower first molars. Loioer First Molar. — The lower first molar usually presents two canals : a large open canal for the posterior root, as seen in Fig. 342, a and b, while the anterior root presents a flat ribbon-like canal very FORMS OF PULP CHAMBERS AND CANALS. 339 difficult of entrance. A transverse longitudinal section of the ante- rior root is shown in Fig. 342, c. In order to effect an entrance to the majority of these canals it is absolutely essential that the rubber dam be applied and the tooth well dried. A section through both roots is shown in Fig. 342, 6. Not uncommonly two distinct anterior canals are found, and in rare instances two distal roots may be present, as shown in Fig. 342, d. The roots of this tooth, as those of the other lower molars, as a rule, bend backward. Fig. 343 (from Ottolengui) shows an exaggeration of this bending. This tooth not infrequently requires canal treatment before the roots are fully formed. A section through the anterior half of an immature Fig. 343. Fig. 344. ^<^ Lower first molar. Lower first molar, immature. tooth is shown in Fig. 344, a ; through the posterior half. Fig. 344, b. Lower Second Molar. — A section of the lower second molar resem- bles that of the first, but distinct double canals in the anterior root are more frequently seen, as shown in the section of the anterior half in Fig. 345, 6. Lower Third Molar. — In the lower third molar the roots are fre- quently compressed together, exhibiting bifurcation toward their apices (Fig. 346). Fig. 345. Fig. 346. Lower second molar. Lower third molar. The canals of any tooth may exhibit constrictions or flexions at any points of their lengths. Although there is no absolute indication as to the presence of flexions or abnormal lengths, an examination of the overlying gum should always be made, when lengths and irregularities may possibly be determined if the gum tissue and alveolar wall be very 340 THE TREATMENT AND FILLING OF ROOT CANALS. thin. If any of these irregularities be present it is important that they be discovered, and additional care be taken to eifect a complete entrance to the canals. Instruments for Canal Treatment. The description thus far has included the territory to be operated upon and its condition as regards sepsis, the agents commonly employed to produce asepsis and antisepsis, and those applied to maintain these conditions. The lirst, the condition of the root canals and dentin ; the second, the various antiseptics employed therein ; the third, the several materials used as canal fillings. The next study includes the instru- ments employed and their specific applications. The first are enamel chisels. These are employed to cut down weak unsupported enamel walls and those portions of enamel removable by such instruments, which interfere wdth direct access to the pulp canals. The next, burs, of several forms; the first, that known as the "dentate fissure bur," for cutting enamel ; next rose, inverted cone, and oval forms for enlarging cavities and removing infected dentin. Xext, several forms of broaches, canal cleanserx, and probes, Gates-Glidden reamers for enlarging canals ; syringes, pluggers, and finally rubber dam and the appropriate selection of clamps. In relation with this latter device, it is to be recalled that demon- strations have shown the saliva to be a highly infective fluid, for the reason that it contains a variety of pathogenic organisms which must be excluded from pulp canals if asepsis of these passages is hoped for. No other single means serves so effectively as isolation by the rubber dam. A variety of syringes will be required, a large instrument for irriga- tion (Fig. 347), to wash away loose debris which may be present in the cavities ; smaller syringes will be required to accurately place definite quantities of medicaments in canals (Figs. 348, 349, and 350). Dentate fissure burs are invaluable instruments fi>r removing por- tions of sound enamel walls which interfere with direct access to the root canals. Cutting from within outward, giving the bur a sawing motion, a groove may in a few minutes be extended across the occlusal face of a molar from a distal cavity to a point directly over the ante- rior root. Large rose, inverted cone, and oval burs are employed to remove the dentin which may obstruct direct entrance to the canals ; these are as a rule to be used with a draw-cut, ])laced first in the deepest portion of the cavity, and while revolving drawn toward the operator. Care is to be exercised that no more than necessary of the walls, particularly the floor of the pulp chamber, is to be burred away, to avoid mechan- ically weakening the tooth. INSTRUMENTS FOB CANAL TREATMENT. 341 The broaches employed are of several forms ; a broach is, accurately speaking, an instrument designed to enlarge openings ; so that the Fig. 347. Fig. 348. Fig. 349. Dental syringe. Minim syringe. J. N. Farrar's alveolar abscess syringe. barbed nerve broach is not employed as a broach but as a pulp-extrac- tor (Fig. 351). They and other forms of extractors (Fig. 352) are used to loosen and remove debris from canals. 342 THE TREATMENT AND FILLING OF ROOT CANALS. Fig. 350. Bulb syringe. The toughness of these instruments is remarkable. They are so tem- pered that thev can be bent in any desired direction and wlien properly manipulated will readily follow a .i)r()ximal surfaces, entrance is gained to the pulp chamber by extend- ing at the palatal aspect of the cavity a groove from the cavity to over the entrance of the pulp chamber (a, Fig. 357). The same rule is observed with the lateral incisors and cuspids. Should the pulp have died subsequently to the insertion of fillings which are mechanically faultless, entrance to the ])ulp canal is made in the basilar pit (n, Fig. 358). For cuspids the opening is made at a higher point, about one-third the way toward the cutting edge. These openings, while they should be large enough to afford free access to the THE CLEANSING OF CANALS. 347 canals, should not be made so large as to weaken the crown, or there is danger of fracturing it when in physiological use. Cavities in bicuspids invading the pulp are usually upon the ap- proximal surfaces ; they are to be extended over the occlusal face of the tooth until access to the canals may be had (see Fig. 359). Fig. 360. Fig. 357. Fig. 358. Fig. 359. Cavity in bicuspid. The same procedures are to be followed in molar teeth. In lower molars if the carious cavity be upon the distal wall, it is to be artificially lengthened across the occlusal face until the probe may be carried directly into each canal (Fig. 360, a) ; the same method is pursued if for a mesial cavity. In upper molars, especial care is required to gain primary access to the anterior buccal root, and tooth structure must be cut away until this access is secured (Fig. 360, 6). Should the carious cavities open upon the buccal faces of the posterior or lingual faces of the anterior teeth, the upper cavity edge, that farthest from the gum, must be extended toward the cutting edge of the tooth until a bent probe may be readily passed to the apex of each root (Fig. 360, c). In operating upon many, or most, of the canals of the posterior teeth it is necessary to bend the pulp extractor or canal cleanser until it is almost or quite at a right angle with the instrument carrier. In the six anterior lower teeth where openings are to be made in them in the absence of large cavities of decay, entrance is etfected through the lingual wall. The advice of Dr. J. Foster Flagg is appended, as to the position of tap openings to be made in the several teeth, when the teeth if carious have not the carious cavity in such position as to aiford access to the pulp chamber : " By means of a diamond drill or an inverted cone bur, a rough spot is made in the centre of the face to be perforated ; this prevents slipping of the spear-pointed drill which is then employed to enter the pulp chamber. The outlines of the chamber are to be obliterated with burs." The dentate bur is a most eifective means of enlarging such openings. " The opening is to be enlarged until a fine probe may be 348 THE TREATMENT AND FILLING OF ROOT CANALS. passed into each canal ; the teeth are tapped in the following sit- uations : Upper Teeth. — Centrals and laterals : On the lingual face. Cuspids : On the tuberosity, or disto-labially. First or second bicuspids : On occlusal or buccal face. First molars : On occlusal, or, as a second choice, on buccal face. Second molars : On occlusal, mesio-ocelusal, or buccal face. Third molars : On mesio-occlusal face. Lower Teeth. — Centrals and laterals : On lingual face just posterior to cutting edge. Cuspids : On disto-labial portion near the gum. Bicuspids : On mesio-buccal face. First, second, and third molars : On mesial, buccal, or mesio-occlu- sal face." Treatment of Canals. The tooth and adjoining teeth being isolated by the rubber dam, direct access to each canal having been gained, the tooth having its walls sterilized and each instrument which has been or is to be used being sterilized, the subsequent procedures depend entirely upon the condition of the pulp chamber, canals, and dentin (and perhaps the peri- cementum), as regards sepsis. One of the several conditions described in the opening of the chapter is present ; which of these it is, governs the therapeusis. First : A case hi which the pulp has been intentionally devitalized and extirjxded. The pulp having been removed en masse it has carried with it, provided of course no organisms have been introduced during or subse- quent to its extirpation, all of the sources of infection. The remote danger is now the existence of small fragments of pulj) tissue which if unremoved might form a soil for the develo])ment of organisms ob- taining entrance to them ; or blood may have escaped into the canals where the dead ]^ul]> was torn from its connection at the apex. These must both be removed. Hydrogen dioxid, being the agent which will most quickly and effectively disorganize the blood corpuscles, is carried into the canals and permitted to act for a few minutes, when it is absorbed by means of cotton, or taper twists of bibulous paper ; then canal cleansers, beginning with the smaller sizes, are employed to scrape the walls of the canals free of any adherent pulp shreds or odontoblasts which may have been torn off when the pulp was removed. I^arger sizes are to succeed these until tlie caliber of the canal is made larger and smooth. If it be a round root and there be any interference with the passage of these instruments to the apex of the root, it is evident that the same difficulty would be found in carrying filling material to its aj)ex. A judicious TREATMENT OF CANALS. 349 Fig. 361. reaming of the root removes this difficulty and is therefore done. That size of the Gates-Glidden reamer which will enter the canal readily is revolved by hand, or, if in the engine, is revolved very slowly, stopping the moment any resistance is felt. The reamer is frequently withdrawn to remove the debris which collects behind it. As soon as resistance is felt, a fine canal cleanser is passed beyond the point and the walls scraped, when the reamer is reapplied ; this alternation of instruments is continued until sensitivity shows that the point of the reamer has reached the pericementum. The next size of reamer is then employed to enlarge the canal uniformly. As soon as a canal is reamed a tem- porary dressing of alcohol on cotton is placed in it to prevent the ingress of debris from other canals — that is, ifit.be a tooth having two or more roots. In upper molars, the palatal, and in lower molars the distal, root is to be first cleansed and dressed. If the subject of operation be a single-rooted tooth, preparation is now made for hermetically sealing the apex and filling the canal ; if a multi-rooted tooth, the canal next in size is entered if the root be round as evidenced by the general shape of the canal. For example, the anterior roots of lower molars, the buccal roots of upper molars or of bicuspids, which exhibit a round opening, have usually but not always a rounded body ; those showing a ribbon-like out- line are likely to have a corresponding outward form. Any efforts at reaming such canals should be confined to that portion showing a rounded opening ; thus, if a lower molar, the finest reamer, rotated by hand, the device of Dr. W. W. Walker (Fig. 361), is employed to enter and enlarge the buccal and lingual extremities of the ribbon-like canals. Any further enlarging should be done with the canal cleansers. The same rule applies to the buccal roots of upper molars and to bicuspids. When any doubt exists, the enlarging should always be done with the cleansers instead of the reamers. Not infrequently cases are found in which the root canals, or one of them, may have such contracted caliber as to refuse entrance to the finest canal cleansers. As a rule, such canals will be found in the buc- cal roots of upper molars and the anterior root or roots of lower molars ; occasionally the bicuspids, particularly the upper first bicuspids, will exhibit this condition. It is in such cases that the method of cleansing and enlarging introduced by Dr. Callahan will be found effective. A rose bur is employed to form a small pit of which the entrance of the pulp canal is the centre. In this pit a drop of sulfuric acid, 50 per cent, solution, is placed ; immediately upon the contact of the acid the Walker pulp-canal reamers. 350 THE TREATMENT AND FILLIXG OF ROOT CANALS. finest size of Donaldson canal cleanser is passed as far as it will go into the canal, the cleanser is inserted and partially withdrawn, scraping away the calcinm sulfate formed by the action of the acid upon the cal- cium salts of the tooth. The acid is quickly neutralized and fresh applications are made drop by drop, the scraping and pumping Avith the cleanser being continued until the point of the instrument is felt to reach or pass the apical foramen. Any organic matter, such as filaments or minute fragments of pulp tissue, Avhicli may have been present in the canal is destroyed. This applies also to organic matter undergoing de- composition or to organisms which may be present. As there is no marked degree of force required in the operation it may be pursued even in cases of pericementitis or acute abscess, to gain direct and free entrance to the seat of morbid action, the focus of germ development. In the event of the operator being unable to detect through instru- mental means the openings of minute canals, Dr. Callahan advises that a pellet of cotton containing a minute portion of acid be placed over the probable situation of each canal and sealed in over night. The follow- ing day, when the rubber dam is applied and the cavity dried, the spot of application of acid will be represented by a small white area, in which, if a canal entrance exist, it will l)e represented by a black dot. A pit is made at this point and acid is applied, when entrance by cleansers is attempted ; should failure to gain entrance result, it is most probable that the canal is almost or quite obliterated with secondary deposits formed by a receding pulp, hence no future sepsis is probable. As soon as the cleanser is felt to touch or pass the apical foramen the canals are syringed out with a saturated solution of sodium bicarbonate. Carbon dioxid is disengaged, which drives the debris left in the canals into the pulp chaml)er, and the acid is neutralized. Thus far has been described the entrance to and thorough cleansing and uniform enlarging of canals of a tooth from which the intentionally devitalized pulp has been extracted ; the immediate question is, What treatment shall now be pursued ? Owing to the method of i)ulp with- drawal, the contents of the dentinal tubules are as yet chemically un- changed ; and it scarcely requires argument to demonstrate that, can they be kept in a stable condition, they constitute the best material for occupancy of the tubules. Examining the list of medicaments applica- ble as preservatives zinc chlorid is the agent fixed upon as the one which will best procure an unchangeable condition of the contents of the tubules. The experiments of Prof. Jas. Truman ' have shown that this agent quickly diffuses through a capillary tube containing albumin, converting it into a whitish coagulum, an albuminate of zinc, which every anatomist knows to be one of the most efficient of all preserva- ^ Proc. Academy of Stomatology, Philadelphia, 1894. THE ROOT-CANAL FILLING. 351 lives. Anatomical specimens of parts injected with a zinc chlorid solution, and which have been subjected to all the conditions known to favor the development of putrefaction, remained nnchanged after the lapse of years. It is advised, therefore — advice endorsed by a majority percentage of operators — that a solution of zinc chlorid be now placed in each canal. A twist of absorbent cotton is dipped in a solution of the salt. Should the apical foramen be large, a weak solution, about 10 per cent., is employed ; if fine, the strength of the solution may be 40 per cent. Unless carelessly manipulated or too great an excess of the coagulant be employed there is but little danger of forcing the solu- tion beyond the apex of the root. After about ten or fifteen minutes the application is withdrawn, and cotton or paper cones passed in the canal to absorb any excess of the chlorid which may be present, and the canals are now ready for filling. The Root-canal Filling. When oxychlorid of zinc has been determined upon as the perma- nent canal filling, the preliminary treatment of the canal with zinc chlorid solution is superfluous, as the coagulating and antiseptic action of the zinc chlorid used in making the oxychlorid cement fully answers the purpose in the short period of time elapsing before chemical com- bination of the fluid and powder results in a hardened body. Examining the available statistics regarding the several materials which have been employed for canal filling in such cases, there is found a greater percentage of success — that is, a fewer number of cases pres- ent subsequent evidences of sepsis — when zinc oxychlorid has been used. This is quite in accord with rational therapeusis ; the material is capable of hermetically sealing the apex and is unchangeable in the conditions surrounding it. Its antiseptic action probably plays little or no con- tinued part, disappearing shortly after the material sets ; it is, however, indisputable that when this material has been employed as a pulp cap- ping it has not infrequently converted the entire pulp into a hyaline coagulum which has remained permanently aseptic. This material is mentioned first on account of the ease, readiness, and certainty with which it may be placed. Gutta-percha ranks second in point of favor as a canal filling ; this not on account of any deficiency of specific properties contraindicating^ its use, but there is not the same certainty of accurate placement and hermetical sealing as with the oxychlorid. Gold and tin, the remain- ing materials which have found any extensive employment in such cases, are open to the same common objection, viz. difficulty of manipu- lation. 352 THE TREATMENT AND FILLING OF ROOT CANALS. These are the practically irremovable materials. The removable materials which have been recommended are, first — Cotton. — It is dne to Prof. J. Foster Flagg that this snbstauce has been extensively employed, not as a filling material per .sr, but as a medium holding an antiseptic. The variety of cotton employed is the crude uncarded cotton wool. Dr. Flagg cites as a proof of the imper- meability of this niaterial when properly packed, that bales of cotton which have floated in sea-water for long periods, when opened show no evidences of moisture in their interior. Evidence regarding the value and danger of this material is con- flicting. It is asserted by the advocates of cotton canal fillings that, properly inserted, they remain unchanged for long periods, are readily packed into position, and if necessity demand may be readily removed. Those who oppose the use of cotton assert that it soon becomes filled with products of decomposition ; and that after some years the texture of the material is destroyed, rendering its removal very difficult. In consequence of these conflicting opinions, the weight of evidence being with those who oppose its use, cotton has found but limited endorsement. The other removable materials, salol and paraffin, are innovations too recent to determine their value and position as canal fillings. The reports regarding salol are sufficiently conflicting to warrant advising its use only in conjunction with a central mass of gutta-percha or tin points ; the salol filling the space between the gutta-percha or metal point and the walls of the canal. These are the arguments for and against the several materials ; the weight of evidence being largely in favor of, first, the oxychlorid of zinc ; and second, gutta-])ercha. The question is, now. When shall the canals be filled ? Shall it be done immediately, or shall a period be permitted to elapse for assurance that no inflammatory action shall arise and tlie filling be a bar to its prompt reduction ? There are two causes which might be productive of inflammatory action : First, the dental manipulations of removing the pul]) and cleansing the canals might be productive of sufficient irritation to give rise to inflammatory reaction ; in that event the open canal would affi>rd an escape for inflammatory effusions. The second danger would depend upon whether septic organisms had been intro- duced or had not been thoroughly destroyed ; their sealing in the canals might be productive of septic inflammation. If the foregoing meas- ures of cleansing have been followed it is scarcely possible that any organisms could survive. General experieuce demonstrates that in but a small j)ercentage •►f cases does the ])eri<'enientum suffer markedly from traumatism during the cleansiug and sterilizing of canals, so that the THE BOOT-CANAL FILLING. 353 weight of evidence clearly teaches that such canals may be filled at once, and little or no reaction occur. Freshly mixed zinc oxychlorid being markedly irritating to vital tissues, it is usual to place between the paste and the tissues of the apical space a barrier to the former. This may be of gutta-percha. A very fine cone of gutta-percha about one-quarter inch long is dipped in oil of eucalyptus or oil of cajuput to soften it ; it is then carried to the apex of the root upon a fine probe and pressed into position. Or, a small pellet of cotton is dipped in a strong solution of thymol or aristol. It is extremely probable that when the freshly mixed oxychlorid is placed over it, the cotton becomes converted into amyloid which her- metically and permanently seals the apical foramen ; the same change occurs in the cotton upon which the oxychlorid is carried into position. Slender wisps of cotton are rolled thin enough to pass readily into the canals. A thin paste of oxychlorid is mixed, the cotton wisps are rolled in it until the meshes are full, when the extremity of a Avisp is caught upon the end of a long, smooth, and slender canal plugger and carried up the canal to contact with the guard at the apex ; the plugger is withdrawn about one-eighth of an inch, and that length of the cotton is crimped upon itself; the remainder of the canal is plugged in the same manner until it is full, when the surplus length of the cotton is cut off and bibulous paper is pressed against the canal filling to absorb the surplus zinc chlorid. The floor of the pulp chamber may be covered with the stiffening paste from the mixing slab. A method by which cotton fiber loaded with the oxychlorid may be carried to the root apex with great accuracy and precision is as follows : The smallest size Donaldson bristle with smooth sides has its hooked end cut off with the scissors and the cut end made flat by rubbing lightly upon a fine Arkansas stone. This may be readily done by grasping the bristle very near to its point between the thumb and index finger and lightly rubbing it back and forth upon the surface of the stone. The bristle is then laid flat upon a glass slab and burnished from heel to point until the surface is perfectly smooth and any burr turned upon the point by the action of the burnisher is fully re- moved. A few fibers of cotton wool are then held between the thumb and index finger of the left hand, the direction of the fibres being in the line of the long axis of the index finger. The point of the prepared broach is then laid upon the cotton fibers, and both broach and cotton are rolled together between the finger and thumb. The rolling action of the finger and thumb serves to felt the cotton fiber on to the l^roach, and should be continued until the cotton is evenly felted over the squared end of the broach. The whole operation is done by the left hand. The broach is not twirled into the cotton with the right hand as 23 354 THE TREATMENT AND FILLING OF ROOT CANALS. Fig. 3(1-2. is ordinarily done where a roughened eotton-carrying probe is used. With a smooth broach and the cotton iiber felted on as described the broach may be pushed forward with considerable force into a canal without puncturing the cotton, which is securely carried as far as the broach will go. On account of the smoothness of the sides of the broach it may be easily withdrawn for a slisfht distance, and then engaGrino;: in the surroundinfr cotton it is used as a plugger to pack the cotton ahead of it, and the plugging action continues until the material is all packed in place. The adjustment of the cotton to the broach as described really forms a tube-like arrangement of the cotton with the instrument in its central lumen — an arrangement greatly fovoring the operation of carrying the cotton into place and enabling the operator to use the cotton or any suitable fiber as a vehicle for canal dressings or for permanent filling in connection with the oxychlorid of zinc cement. If gutta-percha be the material selected for filling the canal, a careful examination is made to determine whether the apical foramen be comparatively large or very small ; in the latter case ehloro-percha may be first pumped into the canals ; in the former it is wiser to omit the fluid, owing to the possibility of passing it through the apical foramen. In all cases where a canal filling is to be made of gutta-percha cones it is advisable to first lubricate the walls of the canal with one of the antiseptic oils, cinnamon, eucalyptus, or cajuput ; these will facilitate the passage of the point to the apex, and as solvents of gutta-percha will soften its surface and permit a more close adaptation to the canal walls. Should the apical foramen be found large enough to admit the pointed extremity of one of the gutta- percha cones, the end of the latter is cut off. The canal is lubricated with the oil, the cone itself dipped in the same medium, its base caught upon the end of a canal plugger, and it is passed carefully into the canal as far as it will go, when the plugger is withdrawn ; blasts of hot air from a hot-air syringe are directed against the exposed end of the cone until it is softened, and it is then pressed firmly into position by means of fine pluggers. A sufficient number of cones are added, softened and packed in position, filling the canal flush with the i)ulp chamber. In fine tortuous canals it is the usual practice to first pump them full of thin ehloro-percha. A portion of the solution is caught be- I Flagg's dress- ing pliers. THE BOOT-CANAL FILLING. 555 tween the points of a pair of Flagg's dressing pliers (Fig. 362) and car- ried to the opening of the canal, when, if the points are opened, the drop of fluid is deposited there ; it is then pumped into the canal by means of a fine smooth broach. To minimize the leakage due to the skrinkage of the chloro-percha in hardening, it is advised to thrust into the fluid material in the canal as large a gutta-percha cone as the canal will admit. Dr. Ottolengui advises that the pieces of silk described in the beginning of the chapter be used and an end left projecting into the pulp chamber, when, should removal of the filling ever become necessary, this end may be caught and the entire filling withdrawn. Should it be designed to fill the canal with gold, its exact length is measured by placing a small disk of rubber dam over a canal plugger, which may be carried to the apex, and inserting the plugger in the canal. The floor of the pulp chamber engages the rubber dam, and when the plugger point has reached the end of the canal the little gauge piece of rubber dam marks its exact length. Minute pieces of soft gold foil are cut, and one by one are carried to the end of the canal, the rubber upon the plugger being the guide to completeness of access to the root apex. This method is to-day rarely followed. Dr. W. S. How advises the use of shredded tin for sealing the apex of canals. By a series of fine probes the canal length is measured (as shown in Figs. 363-367), Fig. 364. Fig. 365. Fig. 363. and particles of shredded tin foil are carried to the apex and impacted by means of measured probes. Salol and paraffin are both manipulated after one manner. A very fine probe is passed into the canal to its apex ; a portion of the ma- terial is caught between the beaks of a pair of dressing pliers (Fig. 362) and held above an alcohol flame until it is melted, when the closed beaks are placed in the canal beside the probe, and opened, and the fluid 356 THE TREATMENT AM) FILLING OF ROOT CANALS. material runs into the canal. Slowly withdrawing the probe, the fluid runs into the space occupied hv the probe, filling the canal to the apex ; it is advisable, however, to warm a broach, and by a jnimping motion Fig. 366. Fig. 367. ensure the carrying of the filling to all parts of the canal. If salol be employed a cone of gutta-percha of such size as may be readily carried to the apex should be thrust into the fluid material, virtually filling the greater portion of the canal with gutta-percha. Several trustworthy observers have noted a disappearance of salol from canals in which it has been placed ; the gutta-percha minimizes the risk attendant u}>on such disa]>pearance. The gutta-percha subserves another purpose : should it ever be necessary to remove the canal filling, blasts of warm air directed against the end of the gutta-percha may be made to melt the salol about it, when the cone may be readily withdrawn. This melting and withdrawal are more quickly accomplished if the central mass be of metal. Paraffin is unchangeable in the conditions under which it is placed. Treatment of Root Canals with Mummified Pulps. The remaining member (tf the aseptic cases is that of mummified pulp. So long as these cases remain perfectly aseptic they give rise to no symptoms and are, as a rule, uncovered by accident, rarely by design. Their usual history is as follows : At some time (perhaps years) before, an exposed or almost exposed pulp has been covered with a cap or cavity lining of the oxychlorid of zinc. They have remained com- fortal)l(' thereafter. At some subsc([uent time it may be necessary to open the tooth, n.-ually on account of recurring caries : the total absence of dentinal sensitivity is noted, the tooth has changed color but SEPTIC CASES. 357 little, if at all, and the operator burs carefully toward the pulp to determine its condition. (It should be remarked here that absence of dentinal sensitivity in a tooth having normal color and which con- tains a very large filling is an indication of aseptic death of the pulp, and the operator should renew all of his antiseptic precautions as to isolation of the tooth by the rubber dam and complete sterilization of all instruments and of the territory of operation.) The burring is con- tinued without any evidence of sensitivity, and the instrument is finally felt to pass into the pulp chamber. There is no odor, no escape of fluid, the pulp being found dry and shrivelled. If sterilized pulp extractors are passed into the canals, the remnants of the pulp may be withdrawn, exhibiting none of the usual signs of decomposition such as odor and confluent softening. It is highly improbable that any organisms are present, unless they should have been introduced by the operator from the exterior. The possibility of this occurring should promjjt caution, for it is the expe- rience of many that although organisms have not been present in the canals, when introduced from without they find a fruitful soil for devel- opment. Reaction indicating infection may occur within a few hours or may be delayed for perhaps two days. This condition may arise even in connection with teeth whose pulps have died under a capping of zinc oxychlorid, from the fact that the quantity of zinc chlorid used in the capping material was insufficient to completely saturate the pulp tissue and render it permanently antiseptic. It is advisable, therefore, to cleanse the canals with some powerful and penetrating antiseptic to destroy any chance organisms and to insert a j)robationary though per- fect root filling until the time of danger has passed. The antiseptic which meets the indications is the ethereal 25 per cent, solution of hydrogen dioxid known as pyrozone, permitted to remain in the canals for several minutes. The canals are then dried, and for the temporary filling salol is the rational indication. At the expiration of three days if no evidences of pericementitis are present the operator may remove the salol, reapply the antiseptic, and fill the canals with oxychlorid or with gutta-percha. The use of formalin (40 per cent, aqueous solution of formic alde- hyde) should be mentioned in this connection. A 5 per cent, solution placed in the canals is a coagulant antiseptic which q\uckly and cer- tainly penetrates into and sterilizes the finest recesses. Septic Cases. The second great class of cases, the septic, comprises those in which the pulp has undergone some extent of decomposition. As a rule, the first organisms which invade pulp tissue are the staphylo- 858 THE TREATMENT AND FILLING OF BOOT CANALS. cocci and stre])tococci, which find a suitable habitat in the live pulp. Advancing first along the lines of the veins, their toxic waste prod- ucts causing inflammation, the organisms invade, peptonize, and liquefy the inflammatory effusions. As these cocci advance toward the apex of the root, the necrotic and altered tissues which are left behind become the breeding-ground of other organisms, particularly the bacteria of putrefaction. The altered portions of pulp tissue are decomposed into products of progressively simpler chemical composition, until all of the albuminous substances have been transformed : first peptones are formed, further decomposition produces ptomains, next such bases as leucin, tyrosin, and the amines, together with fatty acids ; ^ finally the end products are hydrogen sulfid, ammonia, carbon dioxid, and water (see Fig. 305). "Fermentation and putrefaction can only occur rrhere the fnnr/i concerned live, and the extent of decomposition is conditioned by the number of fungi" (Ziegler). As there are several distinct types of decomposition, so is there a cor- responding number of varieties of organisms. The septic cases may be divided into two classes : First : Those in which septic invasion has not passed beyond the apical foramen and given evidence of pericemental irritation or inflammation, these tissues being threatened though not invaded. Second : Those in which the pericementum has become the seat of septic invasion. This latter class is subdivided according to the nature and extent of the septic processes : the first subdivision comprises cases of acute pericementitis non-})urulent ; the second, of chronic peri- cementitis without evident pus formation ; the third, of purulent peri- cementitis, which may be either acute or chronic. 1. In the first of the first class of these cases — those in which the suppurative process has invaded the pulp to near its end — the necrotic portions of the pulp are undergoing putrefactive decomposition. To- w'ard the end of the process, when the apical portion of the pulp is invaded, it is not uncommon to find evidences of pericemental irrita- tion ; this frequently ceases spontaneously, as though the irritation had caused the fi»rmation of a barrier between the tissues of the apical space and the suppurating pulp. An increasing discoloration of the dentin shows the contents of the dentinal tulndes to be also undergoing de- composition. It is necessary to remove this mass, destroying the ])ro(lucts, the eft uses, and the soil of de('omj)osition : this without carry- ing infection to the vital tissues beyond the apex. AVhen the odor of hydrogen sulfid may l)e detected, it is evidence that the ultimate de- composition of albuminous matter is in ju'ogress. As it is quite prol)- able and an imminent danger that organisms might, upon a broach injudiciously employed, be carried from the body of the putrescent 1 Ziegter, Generd Pathohrpj, 1S95. r>. 487. SEPTIC CASES. 359 mass to the apex of the root, it is the part of wisdom and prudence to destroy the organisms as a primar}- measure. There is no quicker or effective means of destroying H2S, and probably the causes leading to its production, than applications of iodin. The reaction involved in the decomposition of HgS by iodin was pointed out by Dr. W. F. Litch : ^ " In passing a stream of hydrogen suliid through tincture of iodin, the latter element seizes upon the hydrogen, forming hydriodic acid, which remains in solution, the sulfur falls as a precipitate ; the solution is decolorized." Any excess of iodin which remains may be readily removed by an application of ammonia water, a solution of ammonium iodid being formed which may be readily washed away. A penetrating antiseptic is now indicated, to sterilize to as great a depth as practicable. A 10 per cent, solution of formalin fulfils this indication. It is permitted to act for some time. The contents of the canal are scraped away, never pushing the broach by which the scraping is done, for fear of carrying organisms deeper into the canal. As the end of the canal is approached 5 per cent, formalin is substituted. As stated, septic canals contain certain fatty bodies and derivatives of albumin, together with more or less partially disorganized pulp tissue and a mixed bacterial infection. Examining the list of therapeutic agents it is seen that one of them, sodium dioxid, possesses properties capable of neutralizing each of the offending elements. This material may be employed either in the solid form or in solution. Solutions of sodium dioxid must be made with great care to prevent escape of the oxygen. A tumbler of distilled water is set in a vessel containing ice- water ; into the distilled water the sodium dioxid is dusted slowly in small amounts. Each addition is attended by the evolution of heat.- The sodium dioxid is added to the point of saturation, and reduced to the desired percentage strength by additions of distilled water.^ A drop of the saturated solution is placed upon a wisp of asbestos fiber (as it destroys cotton fiber) and is carried into the canal ; in a few moments the cavity may be syringed, and a deeper application of the dioxid solution made — this time of 50 per cent, solution. Each time the asbestos is removed it is seen that the discolored dentin surrounding the canal becomes whiter, the discoloring matter in the tubules has been destroyed. When a broach may be passed freely to the apex of the root, and the solution comes away clear from the root, sterilization is presumably ^ Dental Cosmos, 1882. ^ Dr. Wm. Trueman advises that the soldered lid of the can containing the oxid be perforated as a pepper caster, and the sodium dioxid shaken into the distilled water through tlie perforations. ^ E. C. Kirk, Dental Cosmos, vol. xxxv. p. 495. 360 THE TREATMENT AND FILLISG OF ROOT CANALS. complete. A 10 per ceut. solution of sulfuric acid is pumped into the canals by means of iridium broaches ; this neutralizes any free alkali which mav be present. The canal or canals are next washed out with hot distilled water, dried with cotton, filled with alcohol, and well dried by blasts of warm air. Many operators immediately and permanently fill such canals ; however, as there is the possibility that sterilization may not be abso- lute, it is the usual practice to fill the canals tentatively yet perfectly. Salol and a metallic point make an excellent canal filling in such cases. When the canals and dentinal walls are dried by means of the alcohol and warm blast they are filled with salol made very fluid, and the metallic point thrust into the canal containing it. Some slight pericemental disturbance may follow, but quickly subsides under the influence of a counter-irritant applied to the gum over the root (tr. iodin., tr. aconit. et chloroform. <'id. pars ceq. The crown cavity is sealed with sticky temporary stopping for a few days, when if the condition of the pericementum is found normal, the salol filling is removed (if the operator desires) by heating a pair of tweezers and grasping the protruding end of the metal cone. It is the general practice to then fill the canal with oxychlorid or gutta-percha. Should the case present evidences of profound change in the contents of the tubules, /. e. much discoloration, the 50 per cent, solution of sodium dioxid may be sealed in the canal for a day ; the next day the canals are svringed" freely with an acid solution of hydrogen dioxid. Dr. Kirk advises that the dentin be saturated with the sodium dioxid solution, then upon the addition of hydrochloric acid, hydrogen dioxid is formed wherever the sodium has penetrated, and drives out the soapy matters formed by the action of sodium hydroxid upon the products of decomposition. Preliminarv to filling the canals it is the usual practice to fill them for a few minutes with an antiseptic, which will exercise an influence over a considerable period of time. Of all antiseptics, oil of cinnamon gives evidence of the most prolonged presence when so placed. Cases in which Pericementitis is Present. The next class for consideration includes the cases in which the tissues of the apical space arc; invaded. The first evidence of such invasion is tenderness of the tooth upon pressure. The cause of this is, no doubt, the inflammatory reaction of these tissues consequent upon con- tact and absorption of the waste products of organisms which are developing in the pulp canal. In the milder cases the tooth is sore to the touch, is slightly loose and extruded, and the gum over the aifected root is redder than normal. Here, as in all grades of this disturbance, CASES IN WHICH PERICEMENTITIS IS PRESENT. 361 the aim is to get rid, first, of the causes of the inflammation ; second, when necessary to treat the inflammation itself. In entering the canals of such teeth — and of course they should be opened and cleansed as quickly and as thoroughly as possible — " The tooth should receive lateral support against the pressure of the burs used in excavating ; if the cavity be approximal the tip of a finger is placed against the face of the tooth on the opposite side to the bur. Should the direction of entrance be in a perpendicular line a ligature of linen twine having long ends may be tied tightly about the neck of the tooth, and traction exerted as a counter-pressure." ' If the conditions permit, the cleansing and sterilizing are to be well done at once. Should the tooth be too tender to permit the usual manipulations, the gross mass is removed by treatment with sodium dioxid solution or by syringing with meditrina, and stirring with broaches ; then a pellet of cotton saturated with lysol, a strongly alka- line and penetrating cresol, is placed against the putrescent mass ; the gum is painted with iodin at a little distance from the site of the inflam- mation. When quiet is secured, the cleansing and sterilization of the canals should be thoroughly done ; and a dressing of a sedative anti- septic introduced. Campho-phenique or cinnamon oil answers well in this particular. In more pronounced cases the tenderness, extrusion, and looseness of the tooth are more marked ; in case the tooth should contain a filling beneath which a pulp has died — and this is a common history of such cases — the release of the imprisoned mephitic gases is imperative. Ex- ercising counter-pressure, a very sharp and small spear-pointed drill is passed into the pulp chamber ; it may be necessary in cases of extreme soreness to effect this entrance at the neck of the tooth as the shortest path. After a few minutes the opening is syringed out with meditrina ; and a blister is applied over the gum at a distance from the tooth, about two teeth posterior to it. The patient is directed to immediately take a hot mustard foot-bath, and to use frequently a 3 per cent, solution of pyrozone or other strong antiseptic solution as a mouth-wash. When the tooth is much extruded and is kept irritated by striking upon the occluding tooth, it is advisable to place a cap over the tooth posterior to the one affected. A cap may be readily made in a few minutes, by taking an impression in moldine or in plaster of the tooth to be capped, pouring a small die of fusible metal ; drive this into a block of soft lead, and then swage a piece of silver or German silver. No. 26, to fit the die. This cap, covering the occlusal face and about half the walls of the tooth, is attached by means of zinc phosphate, thus securing surgical rest for the affected tooth. It was at one time a general prac- * J. Foster Flagg's Lectures. 362 THE TREATMEST AXD FILLISG OF ROOT CANALS. tice to permit the vent hole drilled at the neck of a tooth to remain open for the escape of the gases of decomposition, consequently the cases were in a constant state of sepsis. The practice is obsolete and is to be unqualifiedly condemned. In cases where the inflammatory action runs high, the tooth is ex- tremely tender, much extruded, and loose, the gum over the tooth be- comes livid, the pulse increases, there is some, and it may be marked, febrile action, the tongue is coated and the breath oifensive. Energetic measures are necessary to avert necrotic action in the apical tissues. In this, as indeed in all cases without exception, the promptness and thoroughness of relief depends })rimarily upon the thoroughness with which the exciting cause of the inflammation is removed, /. e. the septic contents of the pulp chamber. In any case where direct access may be had to the canals, and this is very frequently the case, every effort short of that producing great suffering to the patient should be employed to wash away and broach away the putrescent material, using, where ne- cessary, sulfuric acid to enter the canals, powerful antiseptics always preceding the broach. Lysol is an excellent medicament in this con- nection, and campho-]>henique another. The canal is syringed freely and repeatedly with 3 per cent, pyrozone, which should also be used as an antiseptic mouth-wash. Local bloodletting, as advised by Dr. G. V. Black,' is fre(|uently an effective means for securing relief. Make a deep cut in the gum, clear to the process, the incision to be about one- quarter inch from the margin of the gum and encircling the neck of the tooth ; this will tend toward unloading the engorged vessels of the apical space ; dry cups over the face and to the neck, and always hot mustard foot-baths, are valuable adjuncts. Should the inflammatory disturbance run high, and a full, bounding pulse, coated tongue, marked fever, constipation, headache, and other febrile symptoms appear, attempts should still be made to abort the inflammatory action. After as thorough a cleansing of canals and anti- septic washing as possible under the circumstances, local bloodletting as described and advised by Dr. Litch - is efficient, by means of Swedish leeches, washing the gum, touching it with sugar, then applying the leech, which should ])e first ])laced in a test-tube, the mouth of the tube then being placed over the gum ; when the leech is gorged, it drops back into the tu])e. The mouth is then rinsed with warm water, to continue the bleeding. Quinin in doses never less than gr. vj is given in the hope of limiting the exudation into the inflamed area. As one of the best and most effective means of derivation is the induction of watery alvine dis- charges, the patient may be directed to take a saline cathartic or a rectal ^ American System of Dentistry, vol. i. p. 927. 2 Ibid., vol. i. p. 928. CASES IN WHICH PERICEMENTITIS IS PRESENT. 363 injection of half an ounce of pure glycerin. If the pulse remain full and bounding, and headache persist, tr. aconiti or tr. veratri viridis is to be used as an arterial sedative, gtt. j of the tr. aconiti rad., or gtt. ij of the tr. verfitri viridis, repeated every hour, until the pulse slows and lessens in volume and tension. At bedtime, if the inflammation be not markedly lessened, a sedative diaphoretic is administered, Dover's pow- der in full dose, gr. x, given in hot lemonade ; while the patient is drink- ing the latter he or she is to be well wrapped in hot Ijlankets and the feet and legs immersed in a hot mustard foot-bath. The following morning a saline cathartic — magnesise sulph. sss — is given in a goblet of water. These directions (substantially those given by Dr. Litch, ibid.), may be followed with gratifying results in many cases ; even when the inflammation is not aborted, its violence is almost invarial:)ly lessened. Should the inflammation remain at its height for more than twenty- four hours, it is almost certain that pus has formed, and the indication is to give it exit. A spear-pointed bistoury is thrust through the gum over the apex of the aflected root with such decided force as to pene- trate the process if possible. In the event of not accomplishing this end, the point of a spear-head drill revolving very rapidly is passed through the process to the apical space. Although this operation may be performed very quickly it may be necessary to administer nitrous oxid to quiet the patient and render the drilling painless. Anesthesia may be secured by means of the injection of a drop of a 15 per cent, solution of cocain. Dr. Black has described a painless method of effect- ing an entrance to the apical space.^ A napkin is placed about the parts, the gum dried and touched at the point of election with a drop of 95 per cent, solution of carbolic acid (trichloracetic acid full strength may be used). The necrosed membrane is scraped away by means of a coarsely serrated plugger until sensation is felt, when another drop of acid is applied, and the scratching is resumed until the bone is laid bare ; a sharp chisel is then used to open the apical space. Xo blood should be drawn during the operation except at the last step. The case in its present stage belongs to and is described in the suc- ceeding chapter, upon Alveolar Abscess. In any case presenting in which there is reason to 1)elieve the patient is the victim of syphilis — and alveolar periostitis is an occasional accompaniment of tertiary syphi- lis ^ — the use of large doses of potassium iodid is imperatively indicated. Unless decided measures are taken to abort such cases — and the usual antiphlogistic measures are of little avail — dangerous involvement of the general periosteum may occur, leading to necrosis. Not less than ^ American System of Dentistry, vol. i. p. 928. * See case — Heath, Injuries and Diseases of the Jaws, 3d edition. 364 THE TBEAT3IEyT AXB FILLING OF ROOT CANALS. gr. v} doses of potassium iodid are to be administered every three hours. Should there be evidence of detachment of the periosteum, evidenced by boggy swelling, a bistoury is to be passed boldly to the bone, making a large and free incision. Treatment of Chronic Pericementitis. The most usual form of chronic apical pericementitis is that associ- ated with pus formation, and will be discussed in the succeeding chapter under the head of Chronic Apical Abscess. A not inconsiderable number of cases may be seen in which pus formation is not evident and yet a chronic inflammation is present in the tissues of the apical space. If the pulp chamber be open the cause is evident, and its treatment has been described. A not inconsid- erable number of cases are due to mal-occlusion. This point is to be carefully observed, for it frequently affects teeth containing vital pulps and free from caries. The tooth is slightly loose and sore to pressure. Examination reveals abnormal occlusion, either too severe or in the wrong direction. Should the tooth contain a filling, it usually gives a normal response to applications of heat and cold ; examining the filling a spot is seen marking excessive occlusion ; in both cases grinding off the redundant tooth structure or filling and aj^plying a counter-irritant over the apex subdues the inflammation. Its exciting cause being removed, it subsides. A class of cases is occasionally met with in which there is evidence of sluggish and persistent inflammation about the apices of pulpless teeth which have been filled ; acute inflammatory disturbance of a severe grade occurs but seldom. The most common cause of this con- tinued inflammation is probably the decomposition of a minute filament of pulj) tissue which has not been removed from a canal ; or, again^ well-cleansed canals which have not been filled to the apex. Such cases are those of mild sepsis : perfect restoration to health is only pos- sible by re-cleansing, sterilizing and perfectly filling the canals. These teeth are always more or less hypersensitive even though it be unnoticed, and therefore are not of a full measure of service until cured. Other cases in which there is reasonable assurance of perfect steril- ization and complete filling exhibit vascular sluggishness over the apex of the root. Continued and repeated massage is beneficial,^ the disorder being apparently due to j)aralysis of vessel walls and not to septic causes. The tonus of the vessels may be improved by application of the galvanic current. This principle has wide application in general medicine and surgery. It is to be remembered that when tiic tissues about the apex of a ^ Dr. W. F. Rehfuss, Iiitermitiomd Dental Journal, vol. xi. p. 581. TREATMENT OF CHRONIC PERICEMENTITIS. 365 root have been irritated, it may be for months, by the products of a decomposing pulp, a series of degenerative changes may have occurred in them which recjuire some time to remedy. Sterilization should be prolonged, and too hasty a stopping of the canal be avoided. In such cases, after each periodical treatment the canal should be dressed with some stimulant antiseptic : campho-phenique ; oil of cinnamon, or the admirable 1, 2, 3 mixture of Dr. Black : Oil of cinnamon, 1 part ; Carbolic acid, 2 parts ; Oil of wintergreen, 3 " Repeated applications of tr. aconit. et iodin. are to be made to the gums. A source of chronic apical pericementitis — frequently not detected until abscess has formed and discharged, it may be, at a distant point — is found in the death of a pulp from thrombus or jugulation. At some period the tooth has received a blow, or, it may be, has been moved too rapidly by a regulating appliance, or idiopathic pulpitis has occurred. Years afterward, a chance examination may reveal a deeper color of the gum overlying the tooth than over the others ; by reflected light it ■shows an opacity or discoloration of the body of the tooth. It may be slightly sore to percussion, wdiich elicits a dull souncL " Dead pulp " is diagnosticated ; the tooth is opened under extraordinary antiseptic pre- cautions and cleansed freely with sodium dioxid — the ideal material in this instance — dried, and filled at least tentatively with salol. Another class of cases in which a similar condition of the pulp is found consists of those in which a pulp has died from repeated thermal shock received through a metallic filling placed in too close proximity to it. Although constructive action resulting in secondary deposits is the usual consequence of such irritation, profound degenerative changes in the tissue of the pulp frequently occur at later periods. The treat- ment is the same as in the preceding case. Unless the degree of antisepsis stated be employed in cleansing the canals of such cases, an annoying and it may be an obstinate perice- mentitis is lighted up which is difficult to conquer. A word of caution should be spoken in regard to the importance of the removal of inflammatory troubles, particularly the subacute forms, which affect the apical pericementum. It is supposed and with good reason that not only may tumor formations have their beginning in chronic inflammations ; various reflex disturbances of sensation and of special sense may be traced to such sources ; but any inflammation having such an anatomical situation is a smouldering fire which may •under certain systemic conditions become a pathological conflagration. CHAPTER XVI. DENTO-ALVEOLAR ABSCESS. By Heney H. Burchard, M. D., D. D. S. Definition. — In describing the septic inflammation aifecting the tissues of the apical space in the previous chapter, it was stated that a common result of the inflammatory action Avas cellular necrosis and pus formation ; this condition is known as cdveohir abscess or dento-alveolar abscf.s.^. Although alveolar abscess aifecting some other portion of the peri- cementum may and does occur without death of the pulp/ septic infec- tion and bacterial invasion of the tissues of the apical space from septic pulp canals is the most common source and cause of the affection. The term as technically applied refers to septic apical pericementitis. Causes of Dento-alveolar Abscess. The exciting- causes of the disease process will be found in the pyo- genic cocci and probably other pyogenic organisms which inhabit and develop in the deepest portions of the putrescent pulp, finding entrance to the tissues of the apical space through the apical foramen of the tooth. The ptomains and other waste products formed as the result of the life processes of these organisms cause poisoning and debility of the cellular elements of the part. Even granting that the organisms are present in like amount, there is another element for consideration ; an- other factor is involved which determines to a great extent the occur- rence, time of occurrence, and severity of the disease, /. e. the predispos- ing causes — including under this head the condition of the tissues which favor or deter the development of the organisms. Predisposing Causes. — It is unquestionably true that different in- dividuals will exhibit in their tissues marked differences in the degree of resistance to the invasion of disease causes. It is a well-recognized axiom of pathology that one of the most potent antiseptics, if not the most potent, is an inherent resistance of healthy protoplasm ; that is, healthy tissues offer a barrier to the development of the exciting causes * Cases reported in Proc. Academy oj Stomatolofjy of Philadelphia, 1895. 366 PATHOLOGY AND MORBID ANATOMY. 367 of disease, while tissues which are debilitated through any of the many- causes that affect them exhibit a diminished resistance to the invasion of the causes of acute disease. Prominent among the causes which favor the development and ex- tension of pyogenic processes are the inherited conditions indefinitely classified as strumous. The tissues of children having a family history of, for example, syphilis and tuberculosis, frequently exhibit evidences of lack of vital resistance. They are attacked and readily succumb to agencies which affect children of healthy parentage but slightly if at all. Inflammations about the teeth or of the soft tissues of the mouth run a severe course ; septic affections of the pericementum are attended by involvement of neighboring lymphatics and by evidences of septic intoxication. These predispositions may persist throughout the life of the individual ; as a rule, however, they grow less pronounced or less evident with age. Acquired cachectic conditions of the adult also form a strong pre- disposition to malignant invasion of the tissues by septic organisms. It is a matter of frequent observation that tuberculosis and, in a more pronounced degree, syphilis are constitutional conditions which mark- edly diminish the resistance of the tissues. Inflammatory disturbances which in an individual free from cachexia would probably be circum- scribed, when they occur in the cachectic are diffuse and virulent. Local predisposing causes consist of faulty hygiene, producing debility of the tissues, for it is noted that abscess is more likely to run a violent course in unclean mouths than in those kept free of fermenting masses ; this is a general, though not a universal truth. Pathology and Morbid Anatomy. The pathology of septic pericementitis has been described in Chapter XV. That of alveolar abscess begins as soon as there is death of cellular elements in the exudation. The exudation is liquefied in the focus of the inflammation by the action of ferments ; the leucocytes are invaded by and strive to devour the pyogenic cocci which are present — the species of warfare described by Metchnikoflf; the leucocytes succumb, die, and form pus corpuscles, which are found to contain the pyogenic cocci. The cellular exudate is then broken down into a granular detritus, which, with the dead corpuscles and peptonized effu- sion, constitutes pus. The diplococcus of pneumonia is said to be a constant attendant on alveolar abscess, and this particular organism is believed by Schreier to be the usual exciter of the inflammatory action in these cases. The primary seat of the abscess is usually in the pericementum, between its attachment to the cementum and its attachment to the 368 DENTO-ALVEOLAR ABSCESS. alveolus. From the central cavity of softening the necrotic process spreads peripherally ; cell by cell the inflanimatory wall forming the outlines of the abscess and the exudates are liquefied and the cavity grows larger. The cancellated bone about the apex of the root is involved and becomes the seat of molecular necrosis. Larger and larger grows the volume of the abscess until the periosteum covering the alveolar process is involved, softened, and raised from the bone. The inflammatory action precedes the advance of the pus along the line of least resistance ; and if it run high the periosteum may be softened over quite an extensive area and raised from the bone by the exudation beneath it. The pus penetrating the periosteum, the soft tissues are involved and softened, when the pus breaks through the mucous mem- brane, discharging usually by the shortest route from the abscess to the exterior. The progress of septic destruction is along the line of least resistance, and although as a rule this points immediately above the apex of the affected root, it may follow other directions. In some cases the pus finds exit through the pulp canal of the affected tooth, forming what is commonly though incorrectly known as blind abscess. In these cases the abscess cav- ity is usually comparatively .small, and the inflammatory action is less severe than \ i Kr\ when the pus has a longer path of exit (see Fig. 368). The pus may exhibit evi- dences of semi-encystment. Fig. 368. Fk^. 3()9. Blind abscess at the root of an upper incisor (Black): a, abscess cavity in bone; b, drill hole exposing the pulp chamber for treatment. Acute alveolar abscess of a lower incisor with pus cav- ity between the bone and the i)erio.steum (Black) : a, iius cavity in the bone ; b, pus between the peri- osteum and bone; c, lip: (/, tootli ; e, tongue. Collections may apparently remain in the tissues of the gum for long periods without fistula. A case in practice presented conditions similar PATHOLOGY AND MORBID ANATOMY. 369 to that exhibited in the illustration (Fig. 369) ; it had existed for several years about a replanted tooth, and responded promptly to treatment. In other cases the line of tissue destruction and pus escape is along the pericementum, the pus discharging at the neck of the affected tooth. Many of these cases occur in connection with pulpless teeth which have elongated, or those in which there has already been loss of pericementum. Abscesses upon the upper central or lateral incisors may perforate the nasal floor (see Fig. 370). After a period of marked pericemental Alveolar abscess at the root of a superior incisor discharging into the nose (Black) ; a, large abscess cavity in the bone; h, mouth of fistula on the floor of nostril ; c, lip ; d, tooth. Alveolar abscess at the root of an upper molar discharging into the antrum of Highmore (Black): a, abscess cavity in the bone ; 6, mouth of fistula on the floor of the antrum ; c, pus in the antral cavity. disturbance, the inflammatory action running high, causing pain and swelling of the nostril of the same side, the symptoms may suddenly abate without any evident signs of pus having been discharged. Soon after a purulent discharge may be noted from the nostril, leading to the belief that purulent nasal catarrh (ozena) is present ; many of these cases are diagnosed and treated as ozena. In injection of the pulpless incisor, particularly with pyrozone, the pus and fluid are seen to emerge from the nostril, exhibiting the true source of the pus. Abscesses upon upper second bicuspids and molars may perforate the floor of the antrum (Fig. 371). In the lower jaw the pus may pass out of the alveolar process and fail to perforate the overlying soft tissues, pursuing a path which may lead to its exit upon the face beneath the jaw or chin (Fig. 372). In others the pus may burrow through the body of the bone and open upon the face. (See Figs. 373, 374.) In a case of persistent fistula opening upon the side of the face over .the body of the lower maxilla, there was no evidence of inflammatory disturbance in the edentulous gum. An exploratory incision, made at 24 370 DEXTO-A L VEOLA R A BSCESS. a point indicated by a probe passed into the sinus, revealed the presence of a small root-fragment. Healing of the fistula was spontaneous upon Fig. 372. Fig. 373. Chronic alveolar abscess at the root of a lower incisor with a fistula discharging on the face under the chin (Black) : a, abscess cavity in the bone ; 6, b, b, fistula following in the periosteum down to the lower margin of the Vjody of the bone and dis- charging on the skin. Chronic alveolar abscess of the root of a lower incisor with abscess cavity passing through the body of the bone and discharging on the skin beneath the chin (Blackj: a, very large ab- scess cavity ; b, mouth of the fistula. its removal. Prof. M. H. Crver ^ records a case of abscess opening over the body of the lower maxilla immediately anterior to the groove for Fig. 374. Fig. 375. Fistula passing down through the body of the lower maxilla (Black). Abscess with tortuous sinus opening upon the face: A, tissue of cheek; B, floor of mouth ; C, abscess tract. the facial artery (Fig. 375). A flexible probe passed into the fistula ' Proc. Academy of Stomatology, 1896. CLINICAL HISTORY OF ACUTE ALVEOLAR ABSCESS. 371 appeared to enter the submaxillary triangle ; in the absence of evident dental cause, the case had been diagnosticated and treated as abscess of the submaxillary gland. The direction taken by the probe gave no indication of a tooth being involved. The usual therapeutic measures applied to a submaxillary abscess proving unavailing, a serial examina- tion, one of many, of the teeth of that side was made. In one tooth, the second molar, was a large amalgam filling. The pulp responded, though feebly, to the usual tests for vitality ; upon entrance to the tooth the anterior portion of the pulp was found partially vital, the posterior portion dead and decomposing. The pulp was removed ; antiseptics were pumped through the posterior root, found exit at the fistula, and the causal relation of the putrescent pulp and the abscess was shown by a prompt disappearance of the disease. In one case of abscess upon a lower third molar, the pus made en- trance into the tissues about the insertion of the internal pterygoid muscle. Cases have been recorded in which the pus from abscess about a lower molar has burrowed through the bone and, caught beneath the platysma myoides muscle, it has passed down the muscle, discharging from an opening upon the neck or upon the shoulder. Abscess upon an upper molar may find exit upon the face beneath the malar bone. Occasionally the duct of Steno may be involved in the abscess tract and salivary fistula result. Dr. Black states ^ that the cases of abscess opening beneath the malar bone are usually of the acute variety. As a rule, however, cases which exhibit the pus exit at a dis- tance from the seat of abscess are of the chronic variety. The acute and chronic cases differ as to their clinical histories. Clinical History of Acute Alveolar Abscess. Cases of apical pericementitis in which suppuration occurs usually present pronounced evidences of severe inflammatory action. The throbbing and tenderness, swelling and vascular engorgement are marked ; there may be, and usually is, more or less febrile disturb- ance with its attendant symptoms ; a full, bounding pulse, more or less oedema of the surrounding parts, the eye of the affected side may be injected, etc., as described in Chapter XVII. under the head of Acute Pericementitis. In from twenty-four to forty-eight hours a spot of fluctuation makes its appearance at the summit of the swelling, the spot becomes yellow and soon opens, affording escape to the abscess contents. As soon as the pus has discharged the inflammatory symptoms subside promptly and a persistent fistula remains, communicating with the abscess cavity. This comparatively benign course and termination is not universal. It is not at all uncommon to find cases which at the ^ American System of TJentistry, vol. i. p. 940. 372 DENTO-ALVEOLAR ABSCESS. height of the inflammatory disturbance exhibit evidences of septic intoxication. The septic substances formed by the micro-organisms, and in other cases the organisms themselves, gain entrance to the lymph channels and are conveyed to the nearest lymphatic glands, producing evidences of inflammation in them ; sAvelling and pain of these glands are very common. Cases are recorded in ^vhich streptococci appear to have invaded the subcutaneous tissue, giving rise to marked phleg- monous inflammation. Dental literature contains the records of many cases indicating the occurrence of a pyemic condition consequent upon alveolar abscess ; organisms, by gaining entrance to the blood channels, forming septic emboli. The mild and less severe cases run the average course described. Many of them by finding early exit of the pus through the pulp canal of the aifected root have comparatively light inflammatory disturbance ; in those cases in which the evacuation of the pus is delayed, or in which the opening occurs at points distant from the disease focus, the inflammatory action may be severe and prolonged. If the pus point toward the face, the skin, the subcutaneous tissues, and it may be the in- ternal periosteum also exhibit evidences of marked inflammation ; there is much swelling, the skin may become oedematous, there is redness, heat, and throbbing pain. The external application of poultices by the patient, not at all an uncommon mode of domestic treatment, may aggravate the symptoms, soften the tissues, and induce the progress of the pus to the exterior. If in any of the cases which point in the mouth an undue SAvelling is formed at the height of prolonged inflam- ^^"- ^'^^- ^ matory action, pus beneath the perios- teum is to be feared, the })us stripping the softened membrane from the bone over an area. Should these cases not ob- tain quick relief by evacuation of the pus, necrosis of the denuded bone may occur (Fig. 376). Re-attachment of the perios- teum may take place even after extensive Necrosis of the buccal plate of the Separation, provided the pus be evacuated alveolar process from alveolar ab- pnrlv scess (Black). ^^^ ^^ ' Cachectic conditions exert a strong modifying influence upon the course and termination of alveolar abscess. In strumous or debilitated persons the disease tends to invade neigh- boring structures, whose resistance is lessened. This is well illustrated by a case of obstinate maxillary caries, which destroyed the entire pro- cess of one side, the beginning of the disease being apical j^ericementitis of a lower bicuspid. The carious process became chronic soon after the DTAONOSIS AND PROGNOSIS. 373 extraction of the offending tooth, and persisted until the death of the patient from tuberculosis. Alveolar abscess occurring in syphilitic patients is prone to involve the deep structures, and more or less necrosis is not an uncommon sequel. Clinical History of Chronic Alveolar Abscess. After the subsidence of the symptoms attendant upon the formation and discharge of acute abscess, there is rarely a spontaneous healing or filling of the abscess cavity and tract with healthy granulation tissue ; the development of organisms in the abscess cavity and pulp canal con- tinues and produces a continuance of the suppurative process, forming a chronic abscess. In other cases abscess may have developed without marked inflam- matory symptoms, and yet a prolonged and obstinate pus formation occurs in the tissues of the apical space, the pus finding exit through the pulp canal, constituting what is known as blind abscess, one of the most common of the chronic types. Many of the cases which open upon the face are of the chronic variety ; during the development of the abscess and its discharge there may be but little evidence of inflammatory action about the affected tooth. This is a common history of cases which have followed the death of a pulp through trauma, years before the discovery of the ab- scess. At some period a tooth receives a severe blow, and for some time is the seat of traumatic pericementitis, which subsides : it may be years after that a fistula is established in the mouth or upon the face, without a history of inflammatory disturbance. As pointed . out by Dr. Black, the direction of pus-burrowing in chronic abscess is determined by gravity ; thus, if the abscess be upon a lower incisor the pus may burrow, opening beneath the chin, as shown in Figs. 374, 375. Sir John Tomes ^ has called attention to the tendency of pus to open at the angle of the jaw in abscesses affecting the lower third molars (see cases noted above). Diagnosis and Prognosis. Diag-nosis. — If the pericementum of a pulpless and open tooth have been the seat of acute and marked apical inflammation of septic origin for a longer period than thirty-six hours pus is almost invariably formed, and alveolar abscess is present. The diagnostic symptoms are those of acute pericementitis described in Chapter XVII. In case any marked inflammatory disturbance is found about the maxillary region ^ Dental Surgery. 374 DENTO-ALVEOLAR ABSCESS. either within or without the mouth, examination of the teeth of the aifocted side should always be made, as a large percentage of such in- flammations are of dental origin. Any fistula existing in the maxillary regions, either within or without the mouth, is to be suspected as having origin in a septic pericementitis of some tooth. A soft silver probe is to be passed along the tract to determine its direction and, if possible, which tooth is affected. As a rule, such a tooth will itself exhibit objective evidences of abscess and the patient will give a history of subjective symptoms — those of inflammation of pericementum. Should the tooth indicated as the affected one be free from caries, the thermal test is to be applied to indicate the vitality or the necrosis of the pulp. Should the tooth not respond to applications of cold, it is possible it may offer slight response to applications of heat. It is next examined by light reflected from the ordinary, or better the electric mouth mirror, when, if the pulp be dead, opacity of the crown will be detected. An abscess upon an upjjer incisor opening upon the nasal floor may cause a discharge simulating that of ozena ; an examination of the nose will reveal a teat-like elevation upon the mucous membrane covering the nasal floor and an incisor beneath will be found carious and having a putrescent pulp, or, if non-carious, a history of traumatic pericemen- titis and a present opacity. It may be mentioned here in connection with death of the pulp from traumatism, that continued thread-biting, biting very hard substances such as pieces of ice, nuts, etc., may cause death of the organ, presum- ably by thrombosis. It is possible that the direction taken l)y the probe which is passed into the fistula will point away from the teeth present, passing into a space from which a tooth has been extracted. In that event the pres- ence of a root fragment, or piece of necrosed process, may be suspected.' Should the neighboring teeth be excluded as causes of an inflammation, there should be no hesitation in making an exploratory incision, down to the end of the probe which has been passed into the fistula. Cases of dentigerous cysts have been detected in this manner. This condition would, however, be susjjected when there was an absence of a tooth or teeth from the arch, no evidence jxist or present of pericementitis in any of the teeth of the arch, and a cystic tumor present in the jaw, or it may be a fistula discharging upon the face after a history of maxillary periostitis. Caries or necrosis, although in many cases the result of septic apical pericementitis, may yet exhibit fistuhe opening into the mouth, without ' See case of Dr. Jjlack's, American Systan of Dentistry, vol. i. DIAGNOSIS AND PROGNOSIS. 375 evident connection with the teeth. As a rule, cases of necrosis exhibit marked and wide evidences of chronic inflammation of the tissues over- lying the dead or dying bone ; there are usually several fistulse dis- charging from it. Caries may have but a single fistula and simulate closely ordinary alveolar abscess. Diagnosis is made by passing an excavator through the fistula. Dead bone is readily detected by touch, it has a rotten feel ; in caries the instrument may be passed through the dead bone in various directions, and a characteristic dead sound is elicited by tapping upon it. Careful examination of the teeth must be made in all of these cases, to determine the condition of the pulp and pulp canals. In passing an instrument through a fistula to the apex of an ab- scessed root, where the disease action has been of long duration, it may be found that the apex of the root is denuded of pericementum, and roughened — that is, the apical cementum is necrotic ; foreign deposits may be detected occupying portions of the necrotic area. Prognosis. — There are several factors which enter into the prognosis of a tooth and its surroundings which are aifected by alveolar abscess. First, the severity and character of the inflammatory action and septic invasion. In cases in which inflammatory action is localized and pre- senting none or but little febrile disturbance the prognosis is, as a rule, favorable ; but a slight amount of tissue necrosis occurs. Should, on the other hand, the inflammatory action proceed with volcanic violence, it is possible that not only may the pericementum suffer extensively, but a considerable portion of the periosteum over the process may be raised from the bone during the escape of the pus. Should this separation of periosteum be maintained for more than a few hours, the underlying bone may suffer to the extent of necrosis. In case of marked lymphatic involvement, the neighboring glands being swollen and tender, or even the skin over them exhibiting evidences of glandular inflammation beneath, more or less septic intoxication will probably occur, and un- less the focus of infection be promptly sterilized, septicemia is to be feared. Should evidences of diffuse cellulitis occur, indicating the invasion of streptococci into the adjacent soft tissues, it is a danger signal of threatening pyemia.^ Heath - records a case of oedema of the glottis due to the involvement of the connective tissues about the glottis in the oedema accompanying a developing abscess upon a lower molar. The prognosis is good in a vast majority percentage of cases, when the offending tooth is extracted early in the attack, or at its height ; this applies even with apparently very grave cases ; still the prognosis ^ See case— Dr. E. C. Kirk, Proc. Odoniological Society of Pennsylvania, 1892. ^ Injuries and Diseases of the Jaws, 3d ed. 376 DENTO-ALVEOLAR ABSCESS. as to the retention of the affected tooth is also very good, unless the abscess run a phagedenic course. In many of the cases of chronic abscess having a distant discharge the abscess may be cured and the tooth retained. Other cases obstinately refuse to heal so long as the offending tooth is present. Treatment. Treatment of Acute Abscess. — The general principles of treat- ment of alveolar abscess are those for the treatment of abscess in any part ; the details are of course modified in accordance with the anatom- ical peculiarities of the part to be acted upon. These principles are the removal of all dead matter, together with the active causes of the inflammation and suppuration, /. e. micro-organisms and their products, and the induction of a tissue regeneration which shall serve to restore parts lost through the formation of the abscess. The therapeutic means applied are instrumental and medicinal. The instrumental are the instruments employed to gain access to the focus of disease action, and those applied in the mechanical removal of dead parts. The medicinal measures include the agents employed to wash out the abscess tract ; second, those applied to destroy the active causes of the suppuration ; third, the remedies applied to induce new tissue growth ; and next, those employed to maintain asepsis mitil the healing process is com- plete. The great primary objects in the management of acute alveolar abscess are four : First, if the case be seen early, to use every endeavor to abort the inflammation, as described in Chapter XVII. Second, to limit as far as possible the extent of pus formation, hence tissue destruction ; third, the earliest possible evacuation of the pus which has formed ; fourth, the thorough sterilization of the abscess cavity and its walls. Cases when seen may be at any stage of the disease process from an incipient pericementitis to the establishment of a fistula. The treatment of the early cases is that of pericementitis. In all of these cases one fact is never to be forgotten : that the pulp canals are the centres of infec- tion, and the more quickly and thoroughly they are drenched with powerful antiseptics the more limited will be the inflammatory action both in degree and extent, and the more limited will be the pus forma- tion. Attempts are therefore made to enter and sterilize cavities ptwi pfvisu with the antiphlogistic measures applied to abort or limit inflam- matory action. Treatment of Abscess without Fistula. — Abscess has been de- scribed by the older surgical pathologists as the process through which Nature rids herself of an irritant. This is in a measure true, but it is TREATMENT. 377 essentially a destructive and not a conservative process. Nature does rid herself of the irritant through suppuration ; but it is done at the expense of tissue loss, and the wise surgeon endeavors to remove the irritant and limit the destruction. After the inflammatory action has persisted at its height for twenty-four hours, pus is probably present in the tissues of the apical space ; if immediate exit be given to the pus the inflammatory symptoms will subside. If the tooth be not so sensi- tive as to preclude touch upon it, an endeavor is made, after washing the pulp chamber with powerful antiseptics, to pass a very fine Donald- son's bristle through the apical foramen. In many cases this may be done ; the pus escaping through the canal, the inflammatory symptoms begin to subside. This is a case of acute blind abscess ; its treatment will be first discussed. The conditions existing are more or less remnants of pulp tissue undergoing putrefactive decomposition. The contents of the dentinal tubules are also in process of dissolution. Beyond the apical foramen is a fibrous tissue containing blood-vessels and nerves, in the meshes of which tissue pus is forming. Beyond the spots of suppuration, the tissues, which are in small part fibrous but are mainly osseous, are the seat of inflammation. The pus evacuated, the parts tend to spontaneous recovery provided the sources of irritation be removed. The first step in sterilization is the destruction of putrescent matter in the pulp canals. If the tooth be sore after evacuation of the pus through the apical foramen, the patient is directed to use repeatedly an antiseptic mouth-wash, 3 per cent, pyrozone or any of the solutions of hydrogen dioxid, and report in a few hours, when the broach is again passed through the apex of the root, the canal syringed out with hydrogen dioxid and dismissed for twenty-four hours, when the inflammatory symptoms will have so far subsided as to permit working upon the tooth. At this sitting, a slight flow of pus will still be found ; the canals are syringed, rubber dam applied, but never with a clamp on the affected tooth. Sodium di- oxid either dry or in 50 per cent, solution is placed in the canals, and frequent re-applications made. At the expiration of about a half-hour the canals and abscess cavity are syringed out with an acid solution of hydrogen dioxid, and dried. The canals will now be sterilized and also the general abscess cavity. It is possible, however, and probable, that organisms may still occupy the deeper recesses of the tissue bounding the abscess cavity. The parts forming the abscess wall are of com- paratively low vitality and may not dispose of organisms present as would be done in more vascular tissues. It is the usual practice, there- fore, to apply to them a powerful antiseptic : campho-phenique. Dr. Black's 1, 2, 3 mixture, and lysol are all admirable agents in this par- 378 DEXTO-ALVEOLAR ABSCESS. ticular ; they are pumped into the abscess sac as well as possible, and the excess in the canals wiped away with wisps of cotton. There will be, immediately following this operation, a greater or less amount of exudation from the abscess walls, which diminishes as granulation proceeds about the apex of the root. The condition is one of granulating ulcer. An escape is provided for this exudation by leaving the dried canals unfilled for twenty-four hours, when a loose cotton dressing may be applied, hermetically sealing the cavity com- municating with the saliva after each dressing. In two days the dress- ing is removed, always sterilizing the tooth walls and isolating it when the cavity is to be opened. On the third day a larger dressing of cotton, dipped in cam])lio-phenique and wrung out, may be applied. After two days, should the cotton exhibit little or no evidence of exuda- tion, a firmer dressing is applied, to remain about four days ; the next dressing remains a week, when the abscess cavity should be filled with tender granulations. Pending the organization of the granulation tissue there is probably no better canal filling than sah^l having a core of gutta-percha. It is unirritating and may be applied without causing irritation. Should the effort to enter the apical space through the canal fail, and pus be present, an entrance should be effected through the gum. At a point on the gum immediately overlying the apex of the affected root, a pointed bistoury is quickly thrust down to the bone, the bleeding is encouraged by the use of hot water for several minutes, when a pellet of cotton which has been di])ped into 95 per cent, carbolic acid is laid against the periosteum at the bottom of the cut. In a few seconds a spear drill driven by the engine is passed through the bone into the tissues of the apical space. Any bleeding which may occur is encour- aged as above mentioned. For washing the incisions and the abscess in such cases there is no agent more acceptable than a 20 per cent, solu- tion of phenol sodique, it being both sedative and antiseptic. A thread of floss silk dipped in carbolic acid is passed into the fistula to the seat of abscess, its projecting edge lying upon the gum ; this will prevent too rapid a healing of the fistula. The case now resembles an abscess Mith a fistulous opening, the next variety of acute alveolar abscess ; the treat- ment for ])t)th is the same. Treatment of Abscess •with Fistula. — Cases of acute alveolar abscess discharging through a fistulous opening are either seen when the pus has perforated the bone and is making its exit through the soft tissues, or in cases Avhere the inflammatory symptoms run liigh, the usual methods of aborting the inflammation having failed, pus forms and the abscess discharges ra])idly, it may be within thirty-six hours. The use of pepper plasters and like devices to induce pointing of an TREATMENT. 379 abscess are irrational ; they render no service which cannot be per- formed better and more expeditiously by an incision made down to the bone by means of a sharp bistoury. In all cases of acute apical pericementitis where the swelling of the gum is marked, an early and deep incision is useful and advisable. If pus be already formed and the abscess pointing, escape is afforded it ; if the pus have not yet per- forated the periosteum that structure receives early relief from a condi- tion which might threaten it. The greater the swelling the more imperative is the necessity for this incision, which must be freely made. A sharp curved bistoury is held as a pen, its point directed always toward the bone, and is passed boldly down to the bone immediately over the apex of the root. Inflammatory symptoms, as a rule, subside promptly as soon as exit is afforded the pus. As soon as the tooth may be operated upon its canals are opened freely and, treated as virulently and deeply infected centres, are sterilized with the utmost thoroughness. The usual and satisfactory method of accomplishing this is by means of a 50 per cent, solution of sodium dioxid ; after which a stout syringe filled with 3 per cent, pyrozone is to have its contents driven forcibly through the abscess tract, the application to be repeated until the peroxid comes away clear. A few drops of carapho-ph^nique or Dr. Black's 1, 2, 3 mixture are placed in the pulp canal by means of Flagg's dressing pliers. This may be drawn into the abscess sac along its tract, emerging at the fistulous opening, by a little device of Dr. T. M. Hunter.^ One of the rubber cups used for finishing fillings and cleaning teeth is to have its tool opening filled with gutta-percha, the concavity of the cup moistened and pressed flat against the gum, covering the fistula ; removing the pressure from the centre of the cup but keeping its edges closely in con- tact with the gum, a suction is created drawing the medicament through the abscess tract. The writer has used these cups, but mounted on a No. 300 mandrel (Fig. 377), for this purpose for several years ; indeed the discovery that Dr. Hunter had employed and ad- vised it as a means of emptying abscess cavities was a gratifying surprise, as he states that they serve this purpose admirably. The sterilized canals are now to l)e thoroughly filled with cotton twists or gilling twine which has been dipped in the last-named antiseptic, the crown cavity sealed, and the case dismissed. In twenty-four hours, but a slight serous exudate should be pressed from the fistula. In a ^ Dental Cosmos, vol. xxxiv. p. 82. Fig. 377. 380 DENTO- ALVEOLAR ABSCESS. week the abscess cavity should be healed. In that time a permanent canal filling may be inserted ; but it is wiser to defer the filling of the crown cavity for some time, that is, if it is to be filled with cohesive gold. In case of acute abscess where marked inflammatory symptoms with involvement of neighboring parts persists after the evacuation of the pus, the gum overlying the tooth being purplish and tumid, the tooth very loose, and no diminution of the attendant fever, neighboring structures in addition to the tooth are in danger, and the latter should be extracted. An early and free incision will frequently avert this con- dition and necessity for extraction. Should the case when first seen exhibit marked evidences of involve- ment of the tissues of the face, a threatening of the abscess toward pointing on the face, prompt and active measures are necessary. As a rule in these cases the domestic practice of applying poultices to the face has been followed, and in consequence of this pernicious practice the tissues of the cheek are distended and softened, lessening the suffer- ing but inducing the flow of pus along the line of softening. Com- presses wet with lead-water and laudanum — ^. Pkimbi subacet., oj ; Tr. opii, 5J ; Aquffi, Oj.— M. should be laid upon the face, and an incision made at the line of junc- tion of the cheek with the gum, down to the bone over the apex of the root. As a rule, in these cases the pus has found its way into the tissues of the cheek, but drains through the incision ; a cut must always be made away from, not toward the cheek, to avoid cutting the fiicial artery or any of its branches. Opening upon the face may be averted by this means, even when the pus is beneath the skin. The danger of inclusion of the duct of Steno should be borne in mind should the case be one of abscess upon an upper molar, and energetic measures pursued to prevent the establishment of that annoying trouble, salivary- fistula. Wlien fluctuation of tlic inflaramatoiy tumor U])on the face becomes evident, indicating that an external opening must l)e made, it is prefer- able that it be made with a sharp knife and not by suppuration. Scars left by abscesses discharging spontaneously are irregular and disfiguring, those following clean incision are but a line. A curved bistoury is used to transfix the summit of the swelling, the knife is then carried out- ward, making an incision about an inc^h long. In this as in all cases of abscess where pus is detected the indication is to give it immediate exit. It occasionally occurs that abscess may be found upon the lateral TREATMENT. 381 aspect of a tooth containing a vital pulp. The tooth is free from caries, and is perfectly translucent. The most usual situations of these abscesses are upon the labial faces of the anterior teeth and the buccal faces of the molars, between the gingival margin, which may be intact, and the apex of the root. As a rule the evacuation of the pus and dressing with antiseptics causes a speedy disappearance of the abscess. Left to themselves they discharge as a rule at the gum margin. They are a frequent associate of the condition graphically described by Dr. G. V. Black as phagedenic pericementitis. Believers in the gouty origin of this disorder note their occurrence in gouty patients.' In these cases the abscess is attended by more or less destruction of the pericementum. Cases may be seen in which the abscess involves the tissues near the apex of the root, the pulp being vital ; its death, how- ever, will doubtless result from the invasion. Acute apical abscess may discharge at the margin of the gum, follow- ing the pericementum. These cases are to be treated as abscess with fistula. In some cases subsequent to the treatment of the abscess there appears to be a restoration of the pericementum lost in the formation of the fistula. In others a permanent loss of tissue results. This mode of discharge is common about dead roots which have been in the jaw crownless for a long period ; a resorption of alveolar process has occurred and the root is retained by fibrous tissue. The treatment in these cases is that accorded any and all roots which may not be made serviceable — extraction . Treatment of Chronic Abscess. — For purposes of treatment, chronic abscesses are divided into two classes : those discharging through the pulp canal, what are known as blind abscesses ; second, those dis- charging upon the gum, at the neck of the tooth or in fact at any point through a fistula. The usual condition existent with the blind abscess, is a cavity which may have any volume, its diameters, however, rarely exceeding three-eighths of an inch ; this cavity is bounded upon all sides by a fibrous capsule, analogous to the indurated surroundings of an ulcer; the wall represented by the cementum of the affected tooth may be devoid of fibrous tissue, the pericementum being necrotic. The pulp chamber is the centre of infection ; the abscess cavity is the habitat of l)acteria, which cause the peptonization of the inflammatory exudate from the wall of circumvallation, and destroy the exudation corpuscles, thus producing a continued pus formation. The observation and statement of Dr. Black have been quoted above, wherein he states that gravity largely determines the direction pursued by the pus in chronic abscess. This tendency will be found to exist with the blind variety also. ^ Typical cases are recorded in Proc. Academy of Stomatology of Philadelphia, 1895. 382 JJESTO-AL VEOLAR ABSCESS. The tendency of long-continued pus formation about the roots of the upper teeth will be to progress along the pericementum, resulting in a molecular necrosis of that structure from the apex downward. The condition is represented in Fig, 378. The extent to which the apex of the root projects into a cavity increases with the progress of the necrotic process. In the lower teeth, the influence of gravity carries the suppurative Fig. 378. Chronic blind abscess of upper incisor, showing tendency of pus to progressively destroy peri- cementum owing to the influence of gravity. Chronic blind abscess upon lower tooth, showing tendency of pus to sink into the substance of the lower maxilla owing to the influence of gravity. process away from the apex of the root, the abscess cavity increasing downward (Fig. 379). If the case be seen shortly after the subsidence of the inflammatory attack which may have ushered in the suppurative process, the cavity may be very limited in size, but a trifling amount of the pericementum being destroyed. It is advisable in these cases, after a thorough sterilization of the canals and dentin by means of sodium dioxid, to increase the size of the natural drainage tube, by enlarging the pulp canal : a fine Donaldtjon cleanser should pass freely through the apical foramen. The abscess cavity is now forcibly and thoroughly syringed out with 3 per cent, pyrozone. It is advisable after effervescence ceases to mechanically withdraw, or aspirate the contents of the abscess. This may be readily done by passing the point of a syringe into the canal, filling around it with gutta-percha and withdrawing the piston, when the contents of the abscess will flow into the syringe. Any instrument (syringe) employed for this purpose should soak for hours in an antiseptic before using it in other cases (a 20 per cent, solution of phenol sodique is an excellent TREATMENT. 383 sterilizing agent) ; the same syringe should never be used for any other purpose. A small amount of 25 per cent, pyrozone, ethereal, may now be placed in the canals and pumped into the abscess cavity ; then canals and sac are dried by means of warm blasts, and a wisp of cotton dipped in campho-phenique and wrung out is packed in the canal. The patient reports the day following, and if no discomfort be felt the tooth remains closed until the following day. If upon opening the tooth no evidence of exudation is seen, and no effervescence occurs upon applica- tion of 3 per cent, pyrozone, the drying and dressing are renewed, to remain about three days. If any evidence of pus be detected, the canals and abscess are syringed with weak pyrozone, and a small amount of campho-phenique. Dr. Black's 1, 2, 3 mixture, or myrtol may be pumped into the abscess, and by repeated blowing of warm blasts driven into all parts of the cavity. In twenty-four hours a slight serous flow should be observed, but if after three days any evidence of pus be de- tected, it is the signal to establish an external fistula. This is done in the manner before described. The treatment is now the same as that for the next class : chronic abscesses having fistulous opening. Chronic Abscess with Fistulous Opening-. — In these cases, the canals are opened, and sterilized as in all others by the powerful anti- septics named. The abscess tract is syringed out with 3 per cent, pvro- zone., until bubbling at the external orifice ceases. The canals are filled with campho-phenique, or the 1, 2, 3 mixture, after the dressing-plier method, and drawn into and through the abscess cavity and tract by means of the rubber cup device already mentioned. The canals are filled with cotton saturated with the antiseptic, and, as a rule, the case proceeds rapidly to recovery. Fresh cleansing and dressing are indicated if all evidences of inflammatory action, seen in the gum color, are not absent in three days ; in a week the external fistula should be closed. If after a week the fistula remain open, discharging serum, a sterilized excavator is passed through the fistula and it may detect denudation and roughness of the apical cementum. After a root has been the seat of chronic apical abscess for a long period, not only may the apical pericementum be destroyed (Fig. 380), but the cementum itself may become saturated with the products of decomposition, and invaded by septic eij^o^ic abscess : show- organisms. It is not uncommon to find deposits of ing denudation of 11. iiiii j_ cii apex of root (a to &), calculi upon the denuded cementum. ouch an apex ^j^j^ deposits of cal- ls the source of constant irritation ; it is a foreign ("^lus upon cemen- body, and is to be removed. The operation of removal is technically known as amputation of the 384 DENTO-ALVEOLAR ABSCESS. apex. The canal thoroughly sterilized is to be solidly filled with gutta- percha. A vertical incision is made which includes the fistula and exposes the process ; the opening through the process is enlarged, by sweeping around its borders a large dentate bur. The incision, open- ing and abscess cavity are now packed with cotton saturated with phenol sodique, until all bleeding ceases. The necrosed cementum is now exposed ; a small and extremely sharp fissure bur, driven rapidly, is laid against the distal wall of the root and a constant pressure upon the bur maintained until the dead part is ampu- tated. A sharp scaler may now be employed to round the edges of the root and make the cut surfiice smooth. The cavity is syringed with phenol sodique, to thoroughly remove all blood-clots — favorable breeding-grounds for organisms ; as a final measure the walls are touched with campho-phenique, and the edges of the incision brought together, using if necessary a stitch to unite the upper edges. In the abscess cavity iodoform or nosophen gauze is to be packed, and renewed in a couple of days. For a week the patient is directed to employ repeatedly a mouth-wash of 3 per cent, pyrozone. No attempt should be made to fill such a tooth with cohesive foil for several months. In some of the cases of anomalous root form, such as a sharp bend upon the upper end of the root, and which renders it impossible to gain access to the apex of the root even through the aid of sulfuric acid, it may be necessary to treat the abscess through the fistulous opening. The roots are sterilized and cleansed to as great a depth as possible by the aid of sulfuric acid and fine cleansers, and the endeavor made to force hydrogen dioxid tlirough the apical foramen and out of the fistula by means of a syringe. The cavity of the crown is filled with pink gutta-percha, and through it the nozzle of a syringe filled with 3 per cent, pyrozone is thrust, well up the canal. The piston of the syringe is forced down ; it may be the solution will appear at the opening of the fistula, or it may be the solution will fail to penetrate the fora- men and its backward pressure will force the gutta-perclia from posi- tion. In that event myrtol is placed in the canal, which is filled with thread holding the same material. Three ])er cent, pyrozone is injected into the abscess cavity through the fistula, until effervescence ceases. The nozzle of a minim syringe (Fig. 348), charged with cam])ho- phenique or the 1, 2, 3 mixture is passed into the abscess sac, and a couple of drops deposited. In very many cases the abscess will then proceed to recovery. The treatment should be repeated if necessary. If several dressings applied at intervals of a Aveek do not cause a disappearance of pus formation, amputation of the offending portion of the root will be necessary. An heroic method of treating chronic TREATMENT. 385 abscesses which obstinately refuse to heal is by extraction and replanta- tion.' The method applies alone to single-rooted teeth, although it has been successfully performed upon molars. The patient's mouth is to be sterilized, and the tooth extracted. It is immediately placed in a solution of 1 : 1000 mercuric chlorid at a temperature of 120° F. It has been repeatedly asserted, however, with- out satisfactory demonstration, that the cells of the deeper layer of the pericementum and the cementoblasts, and also the cement corpuscles retain their vitality for some period after extraction, and immediate replantation results in a re-establishment of the physiological union between the tooth and alveolus. It is certain that means and measures which are necessary to thoroughly sterilize the tooth before its reinser- tion would be fatal to any cellular vitality which might exist in the cementum and its covering. The pulp canal is opened from its apex and cleaned out with canal cleansers, and pyrozone 25 per cent, placed in the canal, where it is al- lowed to remain for some time. In the meantime the socket from which the tooth has been removed is syringed out with pyrozone, and should the pericementum not be adherent to the tooth, the depth of the socket is scraped by means of large spoon excavators to remove the tissues implicated in the abscess. The cavity is washed out with pyrozone, and a pledget of cotton which has been dipped in campho-ph^nique is placed in the socket at its bottom. The tooth is dried by means of Avarm air ; the soft tissues, if any be present, at the apex are cut away for about one-eighth of an inch. The canal is filled with gutta-percha or solidly filled with gold, the end of the root cut ofP as far as it has been denuded of pericementum, smoothed, and returned to the antiseptic solution. The cotton is removed from the tooth socket, which is syringed out with 3 per cent, pyrozone, and the tooth returned to posi- tion. It is tied to the adjoining teeth by means of silk ligatures or held in place by an appropriate retaining appliance. Occasionally the seat of an alveolar abscess may be at the bifurca- tion of the roots of a molar. This may occur upon vital teeth OAving to a foreign body being driven beneath the margin of the gums and into the point of bifurcation. In these cases it is noted that the inflamma- tion affects the gum about the neck of the tooth ; over the apices of the roots there may be no evidences of inflammation ; pus forms and dis- charges quickly. Syringing out the tract Avith 3 per cent, pyrozone usually frees it from pus and the offending substance — it may be a bristle of a toothbrush — and the case heals rapidly. Cases are seen in Avhich the gum attachment about the neck of the tooth is unbroken ; and free access may be had to the apex of each root of a tooth manifestly suflering from acute pericementitis, pre- 25 386 DENTO-ALVEOLAR ABSCESS. sumably due to a putrescent pulp. In a day or two a discharge of pus may be noted about the neck of the tooth. Such teeth when extracted exhibit an unmistakable abscess sac in the pericementum at the bifurcation of the roots. Whether the pyogenic organisms have traversed the dentin in the bottom of the pulp chamber and the ceraentum beneath, and thus inaugurated the suppurative process, is undetermined ; it may be, however, that Avaste products from this source following the channel named may have saturated the cementum Avith noxious material and caused the inflammation, or the organisms may have found entrance at the gum margin. The diagnosis of such a con- dition is most uncertain, before pus finds exit at the gum margin. Such a case is to be treated by sodium dioxid, full strength, placed in the floor of the cavity, frequently washed away and renewed until the base of the pulp chamber is bleached lohife. The abscess cavity is syringed out with pyrozone. Another variety of abscess should receive mention : that occurring about lower third molars, affecting the gum tissues partially enclosing the emerging crown. The gum overlying and surrounding the erupting tooth becomes reddened, tumid, and excpnsitely sensitive ; if the inflam- mation be not aborted by timely incision and antiseptic washes, pus may form, and the gum acquire an ulcerous appearance. The treatment is free incision, dividing the swollen gum, and syringing with 3 per cent, pyrozone. If there be ulcerous surfaces they are to be touched with 50 per cent, solution of trichloracetic acid. Occasionally the muscles of mastication may become affected by the inflammatory process, and inability to open the jaws result. Such cases are not uncommon when the eruption of the tooth is delayed by lack of room between the ramus of the jaw and the second molar. The extrac- tion of this latter tooth may be required before relief is secured. Complications op Alveolar Abscess. The complications of alveolar abscess arc due in acute cases to the involvement of other tissues than those commonly affected in the course of abscess formation and discharge. They depend in great part upon peculiarities of the anatomical relations existing between teeth and their surroundings, and, as anatomical variations are not uncommon in these parts, aberrations of disease process may be found with unwelcome fre- quency. An examination of some of Dr. Cryer's sections^ will exhibit in one case the root of a lower second bicuspid penetrating the ])assage- way for the inferior dental vessels aud nerves. It is quite possible that an abscess upon such a tooth discharging about the fibrous sheaths of ^ Proc. of American Dental Association, 1895. COMPLICATIONS OF ALVEOLAR ABSCESS. 387 these vessels might travel to distant parts — backward through the in- ferior dental foramen, or forward through the mental foramen. The roots of molar teeth instead of having their thinnest bony cov- ering overlying their buccal aspects, may have their apices almost per- forating the lingual wall of the bone ; in others the apex of the root of a lower molar is found beneath the line of insertion of the mylo-hyoid muscle. Abscess from such a case as this would probably discharge not into the cavity of the mouth, but in the submaxillary triangle. (See the case of Dr. Cryer's noted early in the chapter.) Dr. Harrison Allen ' records one of these cases. The septic roots of a lower third molar were the exciting cause of pericementitis, followed by osteitis and maxillary periostitis. Pus found exit beneath the mylo-hyoid muscle and gravitated, forming a collection about the hyoid bone, and from that point passed upward upon the face in the line of the facial artery. The abscess in addition pressed directly upward against the floor of the mouth and caused unilateral glossitis, from the mechanical eifects of which upon the organs of respiration the patient died. The duration of the extra-maxillary complication was but four days. In the progressive resorption of the inner substance of the superior maxillary bone which results in the formation of the maxillary sinus, a process which certainly continues longer in some persons than in others, the bony structures may be removed to such an extent that but a thin layer of bone, periosteum and mucous membrane covers the apices of the roots of molars. Dr. Cryer's sections exhibit two cases in which the excavation of the sinus has proceeded down between the roots of an upper molar, creating such a condition that abscess upon either palatal or buccal roots must almost inevitably discharge into the sinus. jS^o doubt many cases of incipient empyema of the antrum are aborted by the early extraction of abscessed molars, the antral complication being unrecognized. It is presumable that most of the cases of empyema of the antrum afford subjective evidence comparatively early, owing to the lighting up of inflammation, and purulent catarrh. The student is advised, in studying the relations of the teeth with the maxillary sinus, to a careful and repeated reference to the sections of Dr. Cryer. He calls attention to a fact frequently overlooked and un- taught, that the orifice of opening connecting the maxillary sinus with the nasal passage is near the roof of the former, so that while the patient is in the erect position collections of fluid must nearly fill the sinus before there is a discharge. In the recumbent position, however, the fluid escapes and may be found in the nostril of one side. This is symptomatic of antral empyema. In acute cases of the antral disease there is much swelling, oedema about the eyelid, etc. ; sharp lancinating ^ GaiTetson' s Oral Surgery, 6th edition. 388 DENTO-ALVEOLAR ABSCESS. pains dart about the jaw. In the chronic cases, large accumulations of pus may occur and not be detected until the bone is thin and bulged, emitting a crackling sound upon pressure. Extraction of the offending tooth furnishes an outlet for the pus. It is usual to attempt the passage of an instrument through the pulp canals into the antrum and endeavor to preserve the tooth. Such a drainage is insufficient ; the wall of the antrum should be perforated. Tlii-; little operation is readily done : At a point about one-eighth of an inch or more above the apices of the roots of the molars an incision is made through the mucous membrane of the buccal alveolar wall, clear to the bone ; a spear-pointed drill, a large one driven rapidly by the engine, is passed instantly through the outer antral wall. The drill is directed upward and inward. The opening is made sufficiently large to permit free irrigation. Into the opening thus made the point of a syringe, perforated to sprinkle, is placed, and the cavity washed out with 3 per cent, pyrozone which has been diluted one-half and made faintly alkaline by the addition of sodium dioxid. As pointed out by Dr. W. H. Atkinson many years ago, unless the irrigating fluid be made faintly alkaline it is irritating. As a stimulant injection to fol- low, Lugol's solution (liquor iodi corapositus, gtt. xx to the ounce) is excellent. The canal of the tooth is to be thoroughly sterilized and filled. In the treatment of other complications, if the case be acute, the im- mediate extraction of the offending tooth and the free use of antiseptic month-washes will usually effect a cure. In the treatment of chronic cases, if the focus of infection, the pulp canals, be made antiseptic and the medicinal agents can be introduced into the abscess tract through- out, surprising cures may result, as the literature of dentistry testifies. Abscess upon Temporary Teeth. — Among the most trying classes of cases with which the dental operator is confronted are those of ])eri- cemental disturbance affecting the temporary teeth. The operator is torn by conflicting emotions : the desire to afford quick relief to the little sufferers and the hesitancy or dread of inflicting the amount of suffering necessary to relieve the acute pain. Fortunately the pain is relatively less than in adults ; the tissues being softer the child escapes the agoniz- ing pain attending the rapid formation of pus in the aj)ical tissues of the adult. The swelling, redness, and febrile disturbance are usually greater in the child than in the adult ; pus forms more quickly and makes its appearance in the gum sooner. The principle of treatment is the same as with the adult — evacuation of the pus. The necessary incision may be made almost paiidessly by em])loying a sharp-pointed bistoury hav- ing a razor-like edge. The child, reassured by a gentle examination and firm kindness, is directed to open tiie mouth and close the eyes, COMPLICATIONS OF ALVEOLAR ABSCESS. 389 when the bistoury, held as a pen, is passed quickly into the swell- ing- The canals of temporary teeth are to be sterilized first with pyrozone, next with oil of cassia, and should be filled with " balsamo del deserto." Dr. W. H. White, to whom we are indebted for the introduction of this material, states that in roots of temporary teeth in which it has been placed the resorptive process is not interfered wdth. Abscess upon children's temporary teeth should receive prompt at- tention and treatment to avoid possible injury to the permanent tooth beneath ; this, however, does not appear to be as frequent as might be supposed. There is a tendency in strumous children toward marked lymphatic involvement attending alveolar abscess ; and secondary abscess of the lymphatic glands is not uncommon. Chronic abscess in the cachectic individual which may not respond to the usual local measures of treatment, may be materially benefited by constitutional treatment. This comprises regulation of the functions of the alimentary canal ; the use of such foods as beef peptonoids, mal- tose, etc. 'Iron and arsenic are administered when the patient is, as is usually the case, anemic. More important than any medicinal thera- jDCutics is systematic exercise in the open air. Raising the bodily tone raises the recuperative power of the tissues, and hitherto resisting dis- ease may be conquered. Perforated Roots. — Perforation of the walls of a root canal expos- ing the pericementum occurs, as a rule, in consequence of two causes : first, the invasion of dental caries ; second, the injudicious or unskilful use of the reamer employed in enlarging canals, or, it may be, burring through the walls in the forming of a socket for the rece23tion of the post of an artificial crown. The direct consequence of the perforation is inflammation of the pericementum, and the usual result is ulceration of that structure. The symptoms and their severity are, as a rule, governed by the situation of the perforation. If this be at the lower half (toward the crown) of the root, there is usually a proliferation of tissue which intrudes upon the pulp chamber. This hypertrophied tissue may increase in amount, a resorption of the edge portion of the process occur, and a fungous mass bearing a close resemblance to fungous pulp bulge into the pulp cham- ber. In fact, in many cases it is impossible to distinguish between the naked-eye appearance of fungous pulp and the condition under discussion. The growth fills the pulp chamber and obscures the per- foration ; it is in addition, in many cases, exquisitely tender. In either event, whether pulp or hypertrophied gum, it is necessary to remove the growth. A spray of ethyl chlorid directed against the mass is perhaps the 390 DENTO-ALVEOLAE ABSCESS. most effective anesthetic ; in a few minutes a sharp fine-pointed lancet is passed around the growth as far as it can be, and the excised portion removed. An application of tannin will check the bleeding ; pledgets of cotton dipped in tr. iodin. are packed against the remainder of the growth and covered in with cotton and sandarac varnish for twenty- four hours. This dressing is renewed from day to day until, if it be a fungous gum, the margins of the perforation are plainly seen. The canal is cleansed, sterilized, dried, and filled with salol and gutta-percha, or with paraffin and gutta-percha, to about half its depth. The re- mainder of the canal and crown cavity are washed out with 25 per cent, pvrozone, and a dressing of temporary stopping applied, filling the per- foration and yet not exercising much pressure upon the soft tissues. In two days the temporary stopping is removed and the cavity is washed out with 3 per cent, pyrozone and dried. A piece of No. 60 gold is cut, larger than the aperture ; this is dipped in chloro-percha and laid over the perforation. A disk of gutta-percha larger than the piece of foil is warmed, laid upon the foil, and pressed against it, sealing it to the cavity walls. The remainder of the cavity is then filled with zinc phos- phate. In case the perforation should be nearer the apex of the root the dif- ficulty is greatly increased. Attempts at passing cleansers to the apical foramen usually result in pricking the pericementum at the perforation and a flow of blood follows, filling the canal. The cleansers are bent so that in passing them to the apex they press against the wall opposite the perforation ; the apical portion of the canal may be detected and cleansed after this manner in some cases. The temporary dressings in these canals should be one of the antiseptic oils, cassia or myrtol. A dressing of oil on cotton should remain a week, and no attempt at canal filling be made until all evidences of pericemental disturbance vanish. A fine cone of gutta-percha is passed, when practicable, into the canal beyond the perforation ; the remainder of the canal is filled with chloro- percha, and the silk points covered with gutta-percha. The canal at the proximal side of the perforation is filled with the solution, ])y means of the long dressing jiliers, the gutta-percha-covered silk being carried gently in position while the general mass is fluid. Balsamo del deserto should apply well in these cases. The canal is filled, or partially filled, with the material, and a large gutta-percha point introduced. CHAPTEE XVII. PYORRHEA ALVEOLARIS. By C. N. Peiece, D. D. S. Definition. — " Pyorrhea alveolaris " is a generic term which, strictly defined, means a flowing of pus from an alveolus. It describes merely a symptom which may be and usually is attendant upon a variety of disorders. The term is applied in clinical dentistry to a complexus of pathological conditions which more or less clearly indicate a specific disease. History, — That pyorrhea alveolaris is not a recent disease, or one due to modern constitutional states alone, is rendered evident from the examination of the skulls of ancient as well as modern races. The alveolar processes of many crania widely separated both in time and in locality exhibit marked impairment of structure which bears the closest resemblance to that presented by processes which were known to have been the result of pyorrhea during life. Recorded observations of this disorder date at least as far back as 1746, when M. A. Fauchard described its essential clinical features, but failed to designate it by any specific term. Following this, communica- tions describing the disease were published by Jourdain in 1778, by Toirac in 1823, and by M. Marechal de Calvi in 1860, in which it was described as a " conjoint suppuration of the gums and alveoli," ])yorrhea inter-alveolo-dentaire, and gingivitis exjjulsiva respectively. The most important contribution to the knowledge of the nature of the disease which had up to that date been made was by Dr. E. Magitot in 1867. In his paper he states that the disease is characterized by a slow but progressive inflammation destructive of the periosteal mem- brane and cementum, proceeding from the neck to the apex of the root and involving the loss of the teeth. From the exact seat of the lesion he designated the disease osteo-periostiti cdveolo-dentaire. Soon after the appearance of the periosteal inflammation, it became complicated with diseases of the gums and the osseous walls of the alveolus, though these are never primarily the seat of inflammation. Magitot regarded the causes of the inflammation as very complex, and to be sought for not in the teeth and gums, but in certain conditions of the general nutri- 391 392 PYORRHEA ALVEOLARJS. tion. The gouty and rheumatic presented the disease most frequently, though its presence in those suffering from diabetes and albuminuria was extremely common. The deposition of tartar on the roots of the teeth, which might at first glance be regarded as playing an important part in the causation of the disease, Magitot considered as accidental and not to be looked upon as a causative agent. With reference to the efficacy of any treatment, however, he advised the removal of the tartar as an indispensable preliminary. The points of diagnosis differentiating between this condition and the former, that of gingivitis, however severe, were also clearly recognized and noted. Following Magitot's able paper was one by Serran in 1880, in which the author took exception to certain of Magitot's views, as well as to the term by which the latter proposed to designate the disease. He recog- nized, however, that the disease was most common in middle life and occurred principally among the gouty, the diabetic, and the albuminuric. He believed that the primary manifestation Avas a local congestion of the gums, followed by an exudation into the peridental membrane which destroyed its vitality and led to the formation of pus and all the other symptoms and pathological conditions characteristic of the disease, A commission composed of MM. Despres, Delens, and Magitot was ap- pointed by the Societe de Chirurgie to consider the statements of Dr. Serran. In this report^ they denied the gingival origin of the dis- ease, and stated their belief that the periosteal membrane and the cementum were the primary anatomical seat of the lesion ; that the succession of morbid phenomena completely precluded the idea of an initial gingivitis ; that the disease begins without any trace of conges- tion of the gums ; that after its formation the pus burro \vs toward the gingival border, which it detaches — without, however, for a time de- stroying its normal aspect ; that only after considerable augmentation of the flow of pus and the loosening of the teeth do the gums become implicated ; that the disease has nothing in common Avith the hyj)othesis of a gingival malady, and that it is most frequently a manifestation of a general state, or a diathesis. Tiiese were the views entertained and pul)lished by French surgeons on the nature of " pyorrhea alveolaris" about the period when the disease began to receive consideration from American dentists. Though pyorrhea alveolaris had long been recognized in the United States and various observations regarding its pathology and treatment had been published, it Avas not until Dr. John AV. Riggs, in October, 1875, read a paper before the American Academy of Dental Surgery, entitled " Suppurative Inflammation of the Gums and Absorption of the Gums and Alveolar Processes," that the disease began to attract the attention ^ Bulletins et Memoires de la Societe de Chirunjie, tome vi. p. 411. HISTORY. 393 its gravity merited. Notwithstanding the views entertained by Magitot and others regarding the constitutional character of the disease, Dr. Riggs in his communication ^ emphatically denied that the disease is an affection of the bone or of the gums, or that it is hereditary or constitu- tional, but, on the contrary, that it is the roughened teeth themselves, in consequence of the accretions from whatever source derived, which are the exciting cause of the inflammation ; that it is purely local in origin, the result of concretions near and under the free margins of the gums, the removal of which even in the third stage is followed by cure. In 1877 Dr. F. H. Rehwinkel^ entered his protest against the theory of the local origin of the disease, and endeavored to prove that it not only may but does exist independently of foreign deposit and must depend on other than merely local causes, and that it is an hereditary and constitutional disease. Dr. L. C. Ingersoll, in 1881, published a paper entitled "San- guinary Calculus," ^ in which it was stated that the persistent flow and discharge of pus along the side of the tooth was caused by an inflamma- tion and ulceration at or near the apex of the root ; as a result of which molecular death the liquor sanguinis escaped from the blood-vessels into the surrounding tissues and became disorganized, the lime salts crystal- lized on the surface of the roots, and formed the deposit which from its origin he designated " sanguinary calculus." This deposition he re- garded as entirely distinct from salivary calculus, and as derived from the blood — the result of inflammatory action and not its cause. In other words, he held that pyorrhea is a local disease but beginning centrally ; that is, at or near the apex of the root. In 1882, Dr. A. Witzell read a paper before the German Society of Dentists,^ in which it was asserted that the primary pathological change was an inflammation and caries of the alveolar border followed by a deposit just beneath the free margins of the gums, Avhich became re- tracted and reverted. The entrance of micro-organisms into this carious region developed pus which became more or less infectious. In conse- quence he termed the disease " infectious alveolitis." He regarded the disease as a primary local alveolitis, having no constitutional relations whatever, a molecular necrosis of the alveoli or caries of the dental sockets produced by septic irritation of the medulla of the bone. In 1886, Dr. G. V. Black prepared for publication probably the most exhaustive paper in print in the United States, wherein pyorrhea ^ Pennsylvania Journal of Dental Seieyice, vol. iii. p. 99. ■^ Report of the Committee on Pathology and Surgery, Trans. American Dental Asso- ciation, 1877, p. 96. ■'* Ohio State Journal of Dental Science, vol. i. p. 189. * Vierteljahresschrift fiir Zahnheilkunde, 1882; British Journal of Dental Science, vol. sxv. p. 153. 394 PYORRHEA ALVEOLARIS. alveolaris is treated as a local disturbance.^ Calcic inflammation and phagedenic pericementitis are the terms he employs to indicate its cha- racter. Though he believes it to be wholly local, he thinks a serumal or sanguinary deposit may be closely allied with its origin. He de- scribes it as a destructive inflammation of the pericemental membrane, distinct from other inflammations of this tissue though having many features in common with them. The disease, he estimates, is essentially one of the peridental membrane rather than of the alveolus, though the destruction of these two structures is so nearly synchronous that it is difficult to say which has gone first. In 1886, Dr. AV. J. Reese read a paper before the Louisiana State Dental Association on "Uremia and Its Eifect on the Teeth,"- in which the chemical, physiological, and pathological relations of uric acid to the general nutrition were discussed. In this communication Dr. Reese ex- pressed the opinion that the inflammation of the pericemental membrane followed by suppuration and disorganization when in contact with the secretions of the mouth, is caused by the deposition of uric acid derived from the blood ; that the disease should be termed " phagedena peri- cementi ; " that " pyorrhea alveolaris " is a misnomer. He also stated that while the tophus on the roots of the teeth is the usual con- comitant of uric acid, it is not necessarily so, but that absorption of the pericemental membrane may take place without any deposit. Though a local treatment was advocated, he stated that without sys- temic or constitutional treatment the return of the trouble may be expected. Dr. John S. Marshall, in 1891, expressed his conviction that pyor- rhea has a constitutional origin and is closely allied to the rheumatic or gouty diathesis ; " 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 formations found in the joints and fibrous tissues of gouty and rheumatic individuals." ^ The writer, in a series of papers published during 1892-94-95,* pre- sented a number of clinical and pathological facts which in their totality it was believed established a kinship between pyorrhea alveolaris or hematogenic calcic pericementitis and the constitutional state familiarly known as the gouty or uric acid diathesis. Recent literature by American writers has dealt largely with the ^ " Diseases of the Peridental Membrane having tlieir Beginning at the Margin of the Gum," American System of Dentistry, vol. i. p. 953. ' Dental Cosm,os, vol. xxv. p. 550. ' '' The Rheumatic and Gouty Diathesis, with its Manifestations in the Peridental Membrane," Trans. American Medical Association, 1891. * International Dental Journal, vols, xiii., xv. and xvi. TERMINOLOGY. 395 problem of the etiology of the disease in question and has been princi- pally concerned in determining whether it is of constitutional origin or of local origin, or of both. Of the more important recent writings on the subject may be mentioned those of Drs. E. T. Darby, H, H. Bur- chard, G. V. Black, M. L. Rhein, E. C. Kirk, James Truman, Junius E. Cravens, Louis Jack, R. R. Andrews, and B. Ottolengui. Terminology. — No disease in the whole domain of surgery has received so many and such diverse names as the one under consideration. Each succeeding title was an attempt at the production of a comprehen- sive descriptive designation of the disease, but when it is recognized that the essential nature of the pathological processes involved is, even now, not fully made out, it is evident that the many names simply represent as many diverse views and can therefore have no permanency, nor do they, indeed, deserve any. The following is a fairly complete list of the synonyms of the dis- order : Suppuration conjointe ; Pyorrhea inter-alveolo-dentaire ; Gingi- vitis expulsiva ; Osteo-periostiti-alveolo-dentaire ; Pyorrhea alveolo ; Cemento-periostitis ; Infectioso-alveolitis ; Pyorrhea alveolaris ; Calcic inflammation ; Phagedenic pericementitis ; Piggs' disease ; Hemato- genic calcic pericementitis ; Blennorrhea alveolaris ; Gouty pericemen- titis. Examining the foregoing list, from the pathologic point of view, it will be observed that there is a wide divergence of opinion as to the conditions which should be included under the generic title of pyorrhea alveolaris. As the term is now understood, pyorrhea alveolaris includes all of those cases of morbid action characterized by the following features : A molecular necrosis of the retentive structures of the teeth (their liga- naent, the pericementum), an atrophy of the alveolar walls, together with a chronic hyperemia of the gum tissue which leads to limited hypertrophy. After a variable period the teeth drop out, and the mor- bid action ceases with their loss. An examination of the roots of the teeth .before or after their exfoliation, usually exhibits deposits of cal- culi upon their surfaces. The disease is generally though not always attended by a flow of pus from the alveoli. Clinically the cases in which these phenomena are observed may be divided into two classes : First, those in which the disease process ap- pears to begin at the gum margin. The second class, those in connec- tion with which there is much controversy, begin at some portion of the alveolus between the unbroken and apparently healthy gum margin and the apex of the root, the pulp of the tooth being alive. These two conditions are so clearly differentiated from one another that each re- quires a separate description. Between these two classes, but intimately 896 PYORRHEA ALVEOLA RIS. associated with the hitter, are to be inchided the cases described by Dr. G. V. Black ' as " phagedenic pericementitis." Class I. Pyorrhea Alveolaris beginning at the Gum Margin (Ptyalogenic Calcic Pericementitis). The first class — those cases beginning not at, but immediately be- neath the gum margin — are perhaps the most common, are by some erroneously supposed to be the only type of cases, and will require description first, as their causes, progress, prognosis, and treatment differ radically from those of the second class. Causes of Class I. — As in any disease, the causes of pyorrhea alveolaris grouped as Class I. may be divided into predisposing and exciting. The predisposing causes may all be included under the head of disorders causing a subacute inflammation of the gingivae. General catarrhal conditions, small but irritating deposits upon the necks of the teeth, as the accumulations upon the teeth of smokers ; fermenting deposits of food ; spirit-drinkers' stomatitis, mouth-breathers' gingivitis; overcrowding of the teeth, mal-occlusion, and non-occlusion. The pre- disposing causes may also frequently be the exciting causes. The excit- ing causes proper are, however, subgingival scaly deposits of calculi. Clinical History. — In the mouth of a patient of one of the above- mentioned classes there will be noted at some period a gingivitis — a sw^elling of the gum which does not extend far from their margins. It is noteworthy that in these cases, as in the succeeding class, it is usual to find the disease attack teeth which are comparatively or quite exempt from the inroads of caries. Soon after the incipiency of the disease there may be squeezed from beneath the gum margins a detritus, of food debris and inspissated mucus. At a later stage a sharp scaler passed beneath the gum margin may detach a flat greenish or black de- posit of calculus. Later, the gingivae are seen to become swollen and are gradually detached from the neck of the tooth, the flattened calculus in- creases in volume, and the irritation and injection of the gum deepens. " It is probable that these deposits have their origin in a reaction be- tween the altered raucous secretion of the gingival glands and the pro- ducts of lactic fermentation, their calcic salts being derived from the saliva." ^ The detachment of the gum does not become marked until these dark scaly deposits have encroaclied upon the margins of the alveolus. Soon thereafter, or indeed Ijcfore, evidences of infection are observed, from the fact that pus may be pressed fi-om the ])ockets. The disease progresses, the teeth loosen, and ultimately drop out or are re- * American System of DentiKtr)/, vol. i. ■^ H. II. Burchard, Denldl Cosmos, October, 1895. PATHOLOGY AND MOBBTD ANATOMY. 397 Fig. 381. moved with the fingers, the injected gum remaining as a flabby mass and all evidences of dental disease ceasing with the loss of the teeth. The process may involve one, two, or more teeth and in some cases an ■entire denture. The origin of these deposits as well as those of ordi- nary calculi are so clearly traceable to the saliva that the writer has suggested for the conditions caused by them the name of ptycdogenic calcic pericementitis. Pathology and Morbid Anatomy. — The appended figure, semi- diagrammatic, will illustrate clearly the nature of the disease process (Fig. 381). It represents a longitudinal section through a tooth and its alveolus, with the vascular supply to the tissues. The peri- cementum and alveolar walls for some distance from the apex of the root are in a healthy condition. At the neck of the tooth are seen two deposits of calculi (a, a). The overlying gum (6, h) is seen to be swollen and tumid at its edges. Immediately below the calculus, where it encroaches upon the pericementum, the latter tissue and also a portion of the alveolar periosteum is seen to have under- gone necrotic changes {d). The portion of alveolar wall uncovered by periosteum is in process of dissolution. In the pocket beneath the ■calculus a collection of pus is seen (c, c), so that the tissues beyond the calculus are involved in suppura- tive degeneration, which may be slow ■or rapid in its progress. The diagnosis is by sight and touch and not infrequently by odor, as par- ticularly in unhygienic mouths an offen- sive odor attends the progress of the disease. The gums are tumid ; from about the necks of the teeth pus may be pressed, and touch demonstrates the presence of flat, dark, and firmly ad- herent scaly calculi. The prognosis is favorable at even advanced stages, provided certain con- ditions may be obtained, viz. a removal or correction of the predisposing causes and a perfect removal of the exciting causes. Treatment. — The treatment is based purely upon the existing conditions, with two main objects in view. ■The first is to remove every source of irritation ; the second, to procure surgical rest until there is a return of the surrounding tissues to a normal condition. Ptyalogenic calcic pericementitis (Burchard). 398 P YORRHEA A L VEOLARIS. As a general rule the first step of the operation consists in a careful and thorough scaling of the teeth. It is essential that the use of bulky- sealers be avoided — first, for the reason that they rarely reach the deepest portions of the deposits ; second, that if they do, they cause more or less laceration of the gum, Avhich should be kept as free from injury as possible. The instru- ments employed for this purpose by a majority of operators are the set known as Cushing's scalers (Fig. 382). Their mode of appli- cation and their position relative to the root are shown in Figs. 383, 384. No instrument with a draw cut can remove these deposits with the same thoroughness as one operated with a push cut. With proper guarding it is improbable that these instruments should do harm to the vital parts beyond the calculus. Great care should be exer- cised in the use of pushing instruments to avoid forcing the dislodged particles into the deeper tissues. The scaling is a tedious operation, but one Avhich should be persisted in until the root of the affected tooth is absolutely smooth. The scal- ing is alternated with a washing out of the pockets with 3 per cent, pyrozone or hydrogen dioxid, which washes out the detached particles of calculus and disinfects the parts. " When the gums are tumid and interfere notably with the scaling pro- cess, applications are made of a solution of trichloracetic acid 1:10 upon cotton tents ; this checks oozing, shrinks the gum, giving a better view of the parts, and tends to soften the de- posits." ' " It not infrequently happens that the teeth have suffered such extensive loss of their retaining structures that the operation of scaling tends to still further loosen them. In these cases the correction of mal-occlusion and splinting the teeth should be attended to before proceeding farther with the ■ operation. The teeth should be ligatured to their fellows, and the excessive occlusion corrected by grinding away the points of contact with corundum wheels sufficiently to relieve the teeth of strain and to permit the fixing of a metallic splint by means of which the teeth may be held firmly, during and subsequent to the scaling operation." - Splints for these cases are usually swaged metallic caps made of ^ E. C. Kirk. ^ H, H. Burchard, International Dental Journal, August 1895. PATHOLOGY AND 3I0EBID ANATOMY. 399 No. 31 metal, gold or silver, which are cemented to the teeth (Fig. 385). When the teeth have suitable forms, a succession of rings sol- dered together may be employed ; in other cases the teeth are lashed together by means of fine gold wire. For temporary use No. 31 or 32 annealed brass wire may be used, and when left m situ for weeks or months it exerts no deleterious eifect. In fact, it appears to possess Fig. 383. Showing the manner of holding an instrument for detaching calcareous deposits when using the pushing motion. The third finger rests on the edges of the teeth, allowing freedom of the hand to make rapid and effectual movements in dislodging the calculi. antiseptic properties similar to those attributed to copper amalgam when used as a filling material. Or, if frequently renewed, floss silk may be used. Devices for this purpose are as numerous as designs for bridge work. Each root is to be perfectly scaled before proceeding to a second tooth. At the completion of the scaling the pockets are freely syringed out with pyrozone 3 per cent., and an application of an astringent made: a 10 per cent, solution of zinc chlorid, 20 per cent, solution of zinc 400 PYORRHEA ALVEOLARIS. Fig. 384. ioclicl, or tr. iodin. U. S. P. diluted one-half with alcohol. Prepara- tions of aristol and the officinal tincture of iodin are also used, all of which subserve the desired end, to sterilize the parts and to constringe the dilated vessels of the gum. An antiseptic and astringent mouth-wash Fig. 385. is prescribed which the patient is to use several times daily. The follow- ing preparation applied on a small roll or tuft of cotton wool or by means of a soft toothbrush admirably meets the conditions : Showing the application of a thin flat instrument to the labial anil approxi- mal surfaces of an upper bicuspid (pushing motion). 'Sf,. Zinci chlorid., cryst., Aquse menthse pip., S. Apply locally to the gums. f.^iv.— M. In a week, should the gums still exhibit tumefaction, or pus be pressed from beneath their margins, exploration should be made to detect any minute calculi, which must be removed. A method of treatment which has given much satisfaction to the writer is as follows : First thoroughly cleanse the mouth and each particular pocket with hydrogen peroxid, electrozone, or some other equally efficient antiseptic. Then with a blunt but flexible broach, gold or steel, let each pocket from which pus has been issuing be very carefully saturated with trichloracetic acid ; this is repeated each visit if ])us continues to flow. Following this, the pockets and gingival borders or margins are thoroughly treated with hydronaphthol and alcohol : ^. Hydronaphthol, Sij ; Alcohol, ,liv. This must l>e used with caution, for it is of sufficient strength to give the patient much discomfort if brought in contact with lips and tongue. The frequency of the visits and apjilications must depend upon the viru- lence of the disease. A wash for the patient's daily use made from the following formula Avill be of great service : GOUTY PERICEMENTITIS. 401 ^. Hydronaphthol, gr. x ; Glycerol, Sj ; Alcohol, Sj ; Aquse dest., §ij. The use of hydronaphthol in pyorrhea alveolaris was suggested by Prof. James Truman. The loss of alveolar walls is permanent ; the utmost the operator can hope in extreme cases is a reorganization of the tissues which have been softened as a consequence of the inflammatory action. Class II. Pyorrhea Alveolaris of Constitutional Origin — Gouty Pericementitis. The second class of pyorrhea cases — those in which local therapeusis has not been attended Avith permanent good results — are usually chronic, extending over a variable period of time, owing to the fact that they are but the local expression of constitutional states. Of these many forms of pyorrhea, one is particularly persistent, terminating only, unless prop- erly treated, with the exfoliation of the affected teeth. This particular form, which has been the subject of much discussion during the past twenty-five years, the writer believes himself to have shown to be but a local expression of the gouty diathesis and directly dependent on the depo- sition of the uric acid, urates, and calcium salts in the pericemental mem- brane. Inasmuch as the origin of the salts is from the blood, the writer suggested the term hematogenic calcie pericementitis. Subsequently Dr. E. T. Darby suggested the happily applicable term gouty pericementitis. Clinical History. — It is noted that many patients who have mag- nificent dentures almost exempt from caries, at a period about middle life begin to have a loosening of the teeth which if unchecked leads to the loss of the entire denture. The disease may be observed at any stage from a slight loosening to impending exfoliation. An exam- ination of many cases will show that although they present apparently diverse conditions, yet beneath these differences there is a striking uni- formity, particularly as to the family history of such patients. A complete and accurate study of the succession of symptoms which a typical case of gouty pericementitis presents from its inception to its termination is rendered difficult, owing to the lack of extended observa- tion of the disease throughout the entire period of its evolution and dis- solution. This is especially true of this disease in its earlier stages. Nevertheless from an attentive study of a large number of individual cases in various stages of development it is believed that a fairly cor- rect picture can be deduced. First as to the teeth themselves ; as stated, they are almost exemi)t from caries, although this is not always true. The teeth frequently 26 402 PYORRHEA ALVEOLARIS. exhibit a tendency to mechanical abrasion upon their cutting edges. If the patient be of the sanguine temperament — and this, with its combinations with the bilious temperament, is the most frequently aifected — the teeth may wear down very much. Between the ages of thirty and forty, as a rule, some of these cases will exhibit a series of excavations usually upon the labial or buccal surfaces of the teeth, which are clearly not due to the causes or progress of dental caries ; it is the condition known as erosion. In nearly all cases, should excavation of cavities in the teeth become necessary, or sections of lost teeth be examined, it will be found that the pulp has receded, /. c. has suffered a continued stimulation of its func- tional activity and it may be almost obliterated. The patient may consult the operator as to the causes of repeated nocturnal attacks of dental neuralgia, or the reason of consultation may be the alteration of position of one or more teeth. An examination of the organs reveals no evident cause for either the neuralgia or the' dis- placement. If the malposed tooth be kept under observation it will usually be seen to become elevated, loosen, and finally drop out. Other teeth become affected in a similar manner. " It will thus be noted that the disorder appears to have three distinct phases : ' First, tooth indura- tion ; second, erosion or chemical solution of the crowns of the teeth ; third, a loss of the retaining structures of the teeth. Pathologically stated, there is a stimulative stage ; second, an irritative, characterized by altered secretion (erosion) ; third, the necrotic." By far the greatest number of cases present themselves when the disease has made marked advance about one or several teeth and their immediate loss is threatened. Assuming that the gouty diathesis however well or poorly developed may be a predisposing cause, and the deposition of some characteristic specific gouty material from the blood into the pericemental tissues the immediate or exciting cause, we have an explanation for the irritation and necrosis of the alveolo-cemental membrane, Avhich even in its early stages is easily recognizable. Coexistent with the pericemental liyper- emia there is more or less redness and turgescence of the gums, accom- panied by a sense of tenderness, soreness, and in many cases neuralgic pain, which latter symptom frequently precedes all other symptoms. In individuals already suffering from pyorrhea, the early irritative stage of the disorder may be frequently observed in teeth previously free from all signs of the disease. In nearly all such instances the focus of the diseased action is confined almost exclusively to the region toward the apical extremity of the root without there being the slightest evi- ^ H. H. Burchard, Proc. PhUadelphia County Medical Society, 1894. GOUTY PERICEMENTITIS. 403 clence of peripheral local gingivitis. Too much stress cannot be placed on this fact, as it unquestionably marks the incipiency of the disease and is one of the early diagnostic symptoms. Somewhere near the apex of the root a distinct swelling occurs simu- lating an acute apical abscess. The tooth is sensitive upon percussion, but less so than when affected by purulent apical pericementitis ; more- over by isolating the tooth it is found to respond to applications of cold, proving that its pulp is alive. A bistouiy passed into the swell- ing is followed by an escape of blood, and usually by a glairy purulent discharge also, although not always. In some cases a probe passed into the opening may show an absence of alveolar process at that point, and by a roughness reveal the presence of a deposit upon the root of the tooth. The teeth so affected usually present an appreciable elevation or protrusion from their alveoli in consequence of the enlarged or thick- ened and congested pericemental membrane. Should this congestion be permitted to continue, the inflammatory stage in consequence of the continued presence of the irritating deposit will supervene, with its con- comitant symptoms, heat, pain, swelling, and marked impairment and in some instances total arrest of the functions of the tissues involved. Inflammation once established will now eventuate in localized sup- puration. The location of the suppurative process, if the case be seen and recognized early, will be found in the large majority of cases to be near the apical extremity of the root. Not unfrequently the pus taking the line of least resistance burrows directly toward the labial or buccal surface and thereby establishes a fistula somewhat similar to one result- ing from acute alveolar abscess from devitalized pulp, though by no means so persistent in character. More frequently, however, the pus burrows its way along the side of the root to the gingival border, thus separating the more vascular tissues from the cementum of the root, and from this locality at the neck of the tooth it is discharged into the mouth, where it mingles with the oral secretions. Once established, these conditions of increased vascularity, tumefac- tion of the gums, and persistent discharge of pus may continue for months or years ; the rapidity with which the disease progresses and the extent to which the lesions develop will be directly dependent upon the state of the general nutrition and habits of the individual. As a result of the continued irritation increased by the deposit, the inflammation extends, the disturbed relation between blood and sur- rounding tissues increases, and the gums become flaccid, spongy, altered in color, and liable to hemorrhagic discharges. Associated with the congested and thickened condition of the pericemental membrane there is a gradual softening and absorption of the alveolar process, which may advance to such an extent as to almost or in some cases quite 404 PYORRHEA ALVEOLARIS. expose the root throughout its entire extent. The tooth thus freed from its retentive structures becomes loose, is freely movable in its enlarged and partially destroyed socket, is extremely liable to dislodgment by slight mechanical means, or if by care these are avoided it will within a limited time be exfoliated in consequence of the final and complete destruction of all its retaining structures. With this final result the progress of the disease is arrested. The alveolar socket being freely opened, the partially dead and decomposing tissues are removed and the remaining structures gradually restored to a normally healthy con- dition by the usual processes of repair. When once established, pyorrhea alveolaris does not confine itself to any one tooth, but may extend to adjoining teeth or make its appear- ance in rapid succession in widely separated regions of the mouth in the lower as well as the upper jaws until the whole denture becomes involved, with an eventual exfoliation of all the teeth and a complete resorption of the alveolar process. When these exfoliated teeth are examined there will be found at some point of the root surface, almost always near the apex, an incrustation of a dark, rough cal- culus, or it may be several of them, all minute. The origin of the deposits being clearly not from the saliva, which is the source of the calculi in the disease described under the head of Class I., it has been called serumal or sanguinary calculus (Ingersoll, Black) ; the writer has suggested as the name of the disease caused by such deposits, hemato- genic calcic 'pericementitis. A chemical analysis of the deposits shows that they are composed at least in part of salts of uric acid. The latter fact has led the writer into an investigation as to the family history of patients who are aifected by this disease. Almost Avithout exception these individuals have been shown to be either the victims of some phase or form of gout, of alleged rheumatism or of rheumatoid arthritis (rheumatic gout), or to have a clear family his- tory of one of these disorders. Careful investigation by several other observers has brought to light similar testimony, particularly within the past three years (Kirk, Darby, Burchard, Jack, and others). It had been noted by succeeding generations of practitioners that the therapeutic resources (local) of dentistry were insufficient to either check or cure the disease condition. All local means of treatment having been exhausted and shown to be of little or no avail, there was a natural inquiry into the exact nature of the predisposing and exciting causes of the malady, so that the therapeusis might be placed ui)on a rational basis. No purely local causes having been found sufficient to account for the dental conditiitartrate, also alka- lithia prepared in the same form as the above-named compounds — com- pressed tablets containing five grains each ; one tablet three or four times daily will be found sufficient. The tablet taken at midday, placed in the mouth for solution without water, has from its local effect a good influence upon the gingival borders. Should the use of these lithia tablets not agree w'ith the patient, the potassium carbonate in ten-grain doses, in some simple bitter — gentian or quassia water — three or four times daily, may be substituted. A valuable adjunct to the medicinal treatment is the free use of alkaline waters, which assist in the elimi- nation of waste products, though it is probable that the good effects attributed to these are largely due to the quantity of liquid consumed. The Saratoga, Vichy, alkaline waters of Wisconsin, the Marienbad, Carlsbad, Apollinaris, etc. have all been found efficacious. Should the patient be very dyspeptic, as is frequently the case, remedies directed to the digestive viscera are of course indicated. If anemia be a concomitant, iron and quinin will be necessary. A combination which has been found of great value in improving the quality of the blood is one of iron and a salt of potassium. Bland's pills, consisting of these two ingredients, is a desirable form for administration; one three times a day will l)e sufficient. There is in addition one factor which may be regarded as therapeutic or at least prophylactic, and which is deserving of more than a passing notice, viz. the exercise of great care in the avoidance of injuries to the ])ericemental membrane, wherever there is a possibility of the presence of the unfortunate diathesis. However ingenious our interpretation of pathological conditions may be, and however jilausible our deductions may appear, the ultimate test of their value will be the readiness with which they yield to and disappear under appropriate treatment. GOUTY PERICEMENTITIS. 417 If pyorrhea alveolaris be a manifestation of the gouty diathesis, and the symptoms and pathological conditions which characterize it be ex- cited and maintained by the deposit and pressure of uric acid and its salts, it should be in general terms amenable to the therapeutic measures which have been efficacious in the treatment of all other forms of gout in other portions of the body. It must be borne in mind, however, that though a case be cured for a period of six months, or even a year, this does not preclude a relapse should the patient return to an improper diet or irregular mode of life. It is hardly necessary to say that this is true of all diathetic diseases. In individuals predisposed to uric-acid accumulations, a new mode of life is to be instituted and followed with extreme care for a long period of time. The conclusions entertained may be represented in a condensed form in the following postulates : (1) Pyorrhea alveolaris of constitutional origin — which is its most destructive and unyielding form — primarily begins as a local inflam- matory disorder in tissues on the side of the root near the apical ex- tremity, and secondarily advances in the very large majority of cases toward the gingival borders. (2) The cause of this inflammation, or gingivitis and pericementitis, is the plasma exudation from the blood-vessels freighted with salts, which in their deposition and crystallization upon the cementum of the root and infiltration of the more vascular tissues, exert the influence of foreign bodies and react as irritants. (3) The salts in question, as disclosed by chemical analysis, are cal- cium and sodium urates, free uric acid, and calcium phosphate. (4) The chemical nature of these salts indicates a condition of the blood in which there is an excess of uratic salts and uric acid due to either increased formation or imperfect elimination. (5) The excess of these salts, as is well known, is regarded by gen- eral pathologists as indicative of a faulty metabolism, and is the imme- diate cause of a series of local disturbances to which the term gouty has been applied, the nutritional disturbance giving rise to what is known as the " uric acid diathesis." (6) An attentive study and accurate observation of the various organs and tissues of patients suffering with pyorrhea alveolaris have disclosed the coexistence, in a very large proportion of them, of one or more local expressions of this constitutional diathesis. (7) Recognition of the fact that a constitutional malady presents itself, one phase of which only has claimed the attention of the dental practitioner, indicates that a treatment designed to be curative must have reference not only to the local expression, but especially to this important systemic condition as well. 27 418 PYORRHEA ALVEOLARIS. (8) Results from constitutional treatment in connection with the usual local applications in a number of well-authenticated cases of pyorrhea alveolaris have been so markedly satisfactory that the writer feels fully justified in his assumptions regarding the origin of the disease. AYliile the foregoing pages embody views quite consistent with an extended experience, yet the writer fully appreciates the fact that many abnormal conditions closely allied in superficial characteristics to those above recognized and described may exist without any other local expressions indicating a uric acid dyscrasia. The association of the class of dental diseases included under the generic title of pyorrhea alveolaris with conditions of general mal- nutrition has been recognized by many writers during the past hun- dred years, but until within very recent times no systematic attempt had been made at their classification. Dr. M. L. Rhein, who has closely studied the relations existing between general disorders and the dental diseases, finding that many general diseases are accompanied by the symptom pyorrhea alveolaris, and that the dental disorder persists so long as the general disease is in activity, suggests that the diseases known under the latter title be divided into two classes — pyorrhea simplex and pyorrhea complex. Under the head pyorrhea simplex are included all of those varie- ties and cases in which local therapeutic measures suffice to effect a cure.^ Pyorrhea complex covers those cases and varieties in which local therapeusis fails to subdue the dental disease, and which are associated with some perversion of general nutrition. This class is subdivided into five groups : («) Those due to nutritional disorders such as gout, diabetes, chronic rheumatism, nephritis, scurvy, chlorosis, anemia, leukemia, pregnancy ; (b) Those occurring during attacks of acute infec- tive diseases, as typhoid fever, tuberculosis, malaria, acute rheumatism, pleurisy, pericarditis, syphilis ; (c) Those due to nervous disorders, cerebral diseases, spinal diseases, neurasthenia, hysteria ; (d) Conditions resulting from the action of toxic drugs — mercury, lead, iodides. Dr. Khein believes from his studies that each member of the group of pyorrhea complex has a distinctive clinical expression, Avhich might be utilized as diagnostic signs of the constitutional conditions. One who is familiar with oral abnormalities and able to differentiate them must be very liberal in the interpretation of causes in order to embrace the wide range of pathological conditions which, in some stages of development, present appearances that would or could very properly be termed pyorrhea alveolaris, yet whose very ready response to topical 1 Dental Cosmos, 1894, p. 780. GOUTY PERICEMENTITIS. 419 remedies would naturally suggest that they were not associated with a uric acid habit. While fully recognizing the fact that this uric acid dyscrasia can be associated with almost any disease which is a concomi- tant of malnutrition, we must remember and fully appreciate the fact that imperfect assimilation of food and faulty metabolism are often responsible for local abnormalities, and at the same time they may be factors in the establishment of a uric acid dyscrasia. In one's judgment of the soundness or unsoundness of theories or hypotheses, the fact must not be overlooked that aifections of the kid- neys, the liver, the lungs, the heart, the mucous membrane, the stomach, etc. may exist without any other recognized expression, or we may have irritation of the pericemental membrane alone associated with any one of them, the disturbance of the normality of this tissue being severe or slight as the functional or organic abnormality of the organ is exalted or inconspicuous. While in the previous pages the treatment advocated had reference mainly to that form of pyorrhea the concomitant of the gouty diathesis, it must nevertheless be borne in mind that a similar condition of the pericemental membrane is at times associated with other perversions of the general nutrition, as pointed out by Dr. M. L. Hhein, and which therefore must receive treatment especially adapted to the general con- stitutional state. Inasmuch as these constitutional conditions are complex in their manifestations and their medicinal and hygienic management almost exclusively in the hands of the physician, the duty of the dental prac- titioner is confined largely to the question of diagnosis ; the local treat- ment, however, must be varied in accordance with the peculiarities of the local pathological condition. CHAPTER XVIII. DISCOLORED TEETH AND THEIR TREATMENT. By Edward C. Kirk, D. D. S. Discoloration of a tooth is consequent upon death of its pulp. While death of the pulp does not always or necessarily involve dis- coloration of the tooth structures, yet when the condition does exist the general cause is as stated. Reference is here made to a progres- sive interstitial staining of the entire tooth structure, and is exclusive of certain metallic stains, and also localized stains resulting from the imbibition of pigmentary matters which occasionally are observed where small areas of dentin have become denuded of enamel covering, or where the latter has been so imperfectly formed as to afford an in- sufficient barrier to the ingress of pigmentary matters from the food or oral secretions. Three classes of conditions are presented for consideration and treat- ment : First, cases where discoloration has resulted from death of the pulp due to causes other than its exposure ; second, discoloration from pulp death consequent upon exposure ; and third, special discolorations due to adventitious causes superadded to the conditions affecting the cases included in the foregoing second division. Any of the numerous traumatic causes which bring about death of the pulp, c. g. blows, sudden contact with hard substances, biting threads, violent thermal shocks, the injudicious application of continuous force in regulating, or the application of arsenous oxid to the dentin (see p. 315), where no exposure or only minute exposure of the pulp exists, may produce hyperemia and congestion of the pulp, or strangu- lation of its circulatory system, the formation of emboli, thrombus, hemorrhagic infarct, etc., leading to a breaking down of the corpus- cular elements of the blood and an infiltration of the tubular struc- ture of the dentin by hemoglobin, giving the tooth a distinctly pinkish hue when examined by direct or transillumination. Teeth so aflPected rapidly change in color through various gradations in tint from the original pinkish hue, which becomes yellow, this, grow- ing darker, passes into brown, and after the lapse of considerable time the tooth may become a permanent slaty gray or black. 420 RATIONALE OF THE PROCESS OF DISCOLORATION. 421 The violence of the pulpitis preceding the death and disintegration of the pulp, in a considerable degree determines the rapidity of the process of subsequent tooth discoloration. Where congestion of the pulp has been relatively slight and the necrotic process has proceeded slowly, the sudden infiltration of the dentin with hemoglobin does not occur, consequently the initial change in color following complete death of the pulp may be so slight as to escape detection except upon most searching examination with special means of illumination, and even then may be manifested only by a slight diminution in the normal translucency of the tooth as compared with adjoining teeth. Such teeth, however, if permitted to remain untreated, eventually grow darker, and while they may not acquire a degree of discoloration equal to those which have suffered sudden and violent death of the pulp, still they become so unsightly as to demand treatment for the restoration of their normal color. The Rationale of the Process of Discoloration. — In teeth dis- colored as a consequence of the death of the pulp without its exposure — viz. those of the first class — it is evident that the sources of pigmenta- tion are internal to the tooth and are to be sought for solely in the products of decomposition of the elements of the pulp tissue and of its vascular supply. The proteid elements of the pulp tissue are complex combinations of carbon, oxygen, hydrogen, nitrogen, sulfur, and phosphorus, which in their gradual breaking down by the process of putrefactive decom- position are split up finally into carbon dioxid, water, ammonia, and hydrogen sulfid, with possibly the formation of traces of phosphatic salts. The group of substances entering into the composition of the histological elements of pulp tissue contains no constituents which in the progressive changes resulting from putrefactive decomposition should form compounds likely to cause permanent discoloration of the tooth structures. When, however, the vascular supply is considered as a factor, the explanation of the cause of discoloration in the cases in question becomes reasonably clear. The red blood corpuscles contain as their characteristic component hemoglobin or oxyhemoglobin according as the blood is venous or arterial, and this substance is its essential coloring ingredient. When undergoing gradual decomposition, hemoglobin passes through a variety of alterations in its chemical constitution, accompanied by a corresponding series of color changes. A familiar illustration of these color changes is furnished by the cycle of color alterations witnessed in a bruise. Immediately following an injury to the flesh, of the character alluded to, an extravasation of blood in the bruised territory occurs, causing undue reddening of the 422 DISCOLORED TEETH AND THEIR TREATMENT. skin ; this is soon followed by an increasing darkening of the tissue, until there results what is popularly termed a " black-and-blue spot." Further decomposition of the coloring matter of the extra vasated blood induces a variety of color changes ranging through the scale of yellows and browns, until the pigmentary matter is finally removed by absorp- tion through the capillary blood-vessel system of the part. In passing through its cycle of color changes, hemoglobin undergoes several alterations in composition during which a number of definite compounds are formed, each having marked chromogenic features. Of these decomposition products, methemoglobin (brownish red), hemin (bluish black), hematin (dark brown or bluish black), and hematoidin (orange), are the most important and best known. While the gradual decomposition of the coloring matter of the blood here noted may and doubtless does account for certain phases of tooth discoloration, other factors which exert a profoundly modifying influence upon the process are yet to be considered. The putrefactive decomposition of the proteid elements of the pulp results, as before stated, in the production of hydrogen sulfid in con- siderable quantity. The albumins contain from 0.8 to 2.2 per cent, of sulfur (Hammarsten) which in the splitting up of the compound during putrefaction yields a large amount of hydrogen sulfid. In pulp decom- position this hydrogen sulfid is generated in contact with the hemoglobin and necessarily exerts a marked modifying action upon the decomposi- tion process of that substance. Miller says, " If a current of sulfuretted hvdrocren is conducted throuo-h fresh blood or a solution of oxyhemo- globin in the presence of air or oxygen, sulfomethemoglobin is formed, \vhich is greenish red in concentrated solutions and green in dilute solu- tions. If we lay a freshly extracted tooth in a mixture of meat and saliva so that a part of the enamel surface remains free, and moisten the surface with blood, it will take on a dirty-green color if kept at blood temperature in an absolutely moist condition for from twenty-four to forty-eight hours. It is quite possible that the dirty-green deposits which form in putrid conditions of the mouth, in stomatitis mercurialis, scorbutica, gangrrenosa, etc., or even in inflammatory conditions of less imjwrtance, as well as in cases of absolute neglect of the care of the mouth, may owe their green color to the presence of sulfomethemo- globin." As in pulp decomposition hydrogen sulfid is being formed in the presence of hemoglobin, this fact warrants tlie belief that a combina- tion takes ])lace resulting in the formation of this same compound, which INIiller regards as productive of certain stains upon the external surface of the teeth. The slaty gray or bluish pigmentation always noticeable upon the RATIONALE OF THE PROCESS OF DISCOLORATION. 423 visceral walls and frequently beneath the skin of animal bodies under- going putrefactive degeneration is a familiar example of the action of hydrogen sulfid upon decomposing hemoglobin in hemorrhagic extrava- sations, and is a process and form of pigmentation exactly analogous to that which is here described as taking place in the dentinal structure from putrefactive decomposition of the pulp. " When red corpuscles are just beginning to disintegrate, the coloring matter formed is hemo- globin ; but the yellow and brown granular masses found in cells and lying free in tissues are, as a rule, derivatives of hemoglobin, not hemo- globin itself. These derivatives are divided into two groups according as they contain iron or not, the former being called hemosiderin, the latter hematoidin." ^ " When acted upon by ammonium sulfid (a deriv- ative of putrefactive decomposition of albumin) hemosiderin becomes black, iron sulfid being formed." ^ Grohe ^ believes that as a result of putrefaction iron is liberated from its compound with hemoglobin, so that when thus freed it readily combines with the hydrogen sulfid. Iron is the most important element to be considered in the list of factors causing the discoloration of this group of cases. It is the iron which is a constituent of the red corpuscles that is the essential chromo- genic factor from first to last in their cycle of color changes. The process of putrefactive decomposition consists of a series of chemical changes wrought out through the agency of micro-organisms, involving the breaking down by successive stages of highly complex organic compounds and their resolution into compounds of much sim- pler constitution. It is not known to what extent this splitting up of the components of the pulp and its vascular elements is ultimately car- ried in the series of changes resulting in the permanent discoloration of the tooth. From what is known of the ultimate composition of the compounds involved it may, however, be safely inferred that, reduced to its lowest terms, the result would be the formation of iron sulfid, the elements of which, with the exception of some unimportant alkaline and earthy salts, are the only ones entering into the original compounds which are fixed and capable of forming a stable residuum in the tubular structure of the dentin. While iron sulfid as such cannot be held wholly accountable for the final bluish-black color of a tooth which has reached the stage of permanent discoloration, the pigmentation is almost certainly due either to it or to some allied compound in which iron and sulfur, with some organic constituents, largely enter, and which by a further slight decomposition would yield true iron sulfid. The significance and importance of a recognition of the possible presence of the iron compound as a factor in tooth discoloration is further brought out in the study of bleaching methods (pp. 427-442). • Ziegler, General Pathology, 1895. ^ Ibid. ^ Virchoiif s Archiv, Bd. xx. 424 DISCOLORED TEETH AND THEIR TREATMENT. Discoloration of Teeth following- Death of the Pulp consequent upon its Exposure, — When death and decomposition of the pulp is consequent upon exposure of that organ, through caries or otherwise, to the irritative influences of infective agents present in the oral secretions and food, or to thermal shock, etc., the putrefactive process involving the pulp tissues is modified in character and rapidity to a degree which mav affect the character of the resulting discoloration. Thus the yel- lowish or brownish discoloration so often seen in teeth whose pulps have been devitalized through systemic or traumatic causes, and which in many cases appears to be more or less permanent in character, is rarely observed in those teeth whose pulps have been devitalized through exposure by caries. In these latter cases the progress of the putrefactive process is com- paratively rapid, the conditions being more favorable so that the color- ing matter of the blood is sooner reduced to its lowest terms in the scale of decomposition products, /. e. to the slaty blue or black pigmentation before noted. In addition to the increased rapidity of putrefactive de- composition incident to cases of discoloration following pulp exposure, another and important modifying factor in the process of discoloration is the ingress afforded to the oral fluids, food materials, and other ad- ventitious substances which find their way into the mouth and ulti- mately, through the open cavity of the tooth, to its pulp canal and thence to the tubular structure of the dentin. These extraneous sub- stances, in the course of time, may infiltrate the tooth structure, and while no especially noticeable or characteristic efl'ect so far as color is concerned may be observed, yet they frequently exert an influence upon the coloration of the tooth which so alters its character as to render successful bleaching treatment extremely difficult and a resort to special methods or a variety of methods necessary. The introduction of fatty or oily substances or of astringent and coagulant matters, for example, may act upon the coloring matter in such a way as to permanently " set " it in the same manner that mor- dants form insoluble compounds or lakes with the dye-stuffs used in the dyeing of textile fabrics. Another and important class of substances which frequently are tlie cause of staining of the tooth structure are metallic salts Avhich are used in dental therapeutic treatment or are accidentally formed during the application of corrosive medicaments to the teeth, through the action of such remedies upon fillings in fsitu or upon the instruments bv which the applications are made. For example, the use of iodin or sulfuric acid in connection with steel instruments and the subsequent use of medicaments containing tannin as an ingredient. The treatment of these conditions will be sei)arately considered. TOOTH-BLEACHING— USE OF CHLORIN. 425 Tooth-Bleaching. — Use op Ohlorin. Nature of the Problem Involved in Tooth-Bleaching. — The bleaching process is dependent upon a chemical reaction between a com- pound having color and some substance capable of so affecting its com- position that the color is discharged, or, in other words, of so affecting the integrity of the color molecule as to destroy its identity, which results in a loss of its distinguishing characteristic, viz. its color. The substances concerned in discoloration of tooth structure, as has been previously shown, are derived from the organic contents of the tubular structure of the dentin, the pulp and its vascular elements, through the gradual putrefactive processes which become operative subsequent to the death of the pulp. These pigmentary products of pulp decomposition we know to be organic in character ; and further, that they exhibit the property of color by virtue of definite conditions of molecular composition — that is to say, a certain arrangement of a definite kind and number of atoms has resulted in the formation of a molecule having its individual group of chemical and physical prop- erties, among Avhich latter is a characteristic color. Whatever brings about an alteration in the composition of the mole- cule at once destroys the identity of the matter so treated. Hence if we can act upon the coloring matter which gives rise to the staining of a tooth by means of an agent capable of effecting an alteration in the atomic arrangement or composition of the color molecule, we may expect to remove or discharge its color feature. Two general classes of substances have been successfully used as bleaching agents : First, those which act by virtue of their power to evolve oxygen in the active or nascent condition, and known as oxidiz- ing agents ; second, those which act in an opposite manner by virtue of their strong affinity for oxygen and which are called reducing agents. The oxidizing bleachers destroy the identity of the color molecule by seizing upon its hydrogen element to form water. The reducing agents act by removing the oxygen atom from the color molecule to form by- products depending upon the character of the reducing agent used. Chlorin and its associates iodin and bromin act as indirect oxidizing bleachers ; the dioxid of hydrogen and of sodium are direct oxidizers. Potassium permanganate may also be classed with this group, though its successful use as a bleaching agent depends upon a subsequent treat- ment of the substance to be bleached with some solvent capable of re- moving the manganese dioxid formed as a by-product of the action of the permanganate. It has somewhat extensive and satisfactory use as an agent for bleaching sponges, and has been used for bleaching teeth, but is of greatly inferior value to other agents for the latter use. 426 DISCOLORED TEETH AND THEIR TREATMENT. The only agent belonging to the group of reducing bleachers which has thus far been found available for bleaching teeth is sulfurous oxid, either in the gaseous condition or in aqueous solution. Chlorin as a Bleacher. — The general use of chlorin as a bleaching agent in the arts no doubt suggested its use in the treatment of tooth discoloration. Its introduction as a tooth-bleaching agent, as well as the assembling of the general principles of tooth bleaching into a co-ordi- nate system, are due to Dr. James Truman, whose method depends upon the liberation of chlorin from calcium hypochlorite, commonly called bleaching powder or "chlorinated lime," in the pulp chamber and cav- ity of decay in the tooth. Chlorin is liberated from the bleaching pow- der by the action of dilute acetic acid ; this taking place in contact with the discolored structure, it is rapidly bleached as a result of the action of the chlorin upon the coloring matter contained in the dentinal tubules. Numerous modifications of this original method of bleaching tooth struc- ture have been suggested, but, as the ultimate result in each is accom- plished through the activity of chlorin, a rational understanding of the mode of action of chlorin in this relation is of importance as an aid to the intelligent use of those methods for tooth-bleaching which are dependent upon or owe their efficacy to that agent. Chlorin is an elementary gaseous body, greenish in color, soluble in water, having a disagreeable odor, intensely irritating to the air-passages when inhaled, and poisonous when breathed in sufficient quantity. It has a strong affinity for all metallic bodies, entering into direct combi- nation with a number of them, under favorable circumstances, with great energy — forming, as a rule, compounds that are soluble in water. One of its distinguishing features and one which is directly concerned in its use as a bleaching agent is its strong affinity for hydrogen. So strong is this affinity, that when a molecule of chlorin is brought into contact with a molecule of water under favorable conditions, the hydro- gen of the water molecule is seized upon by the chlorin to form chlor- hydric acid and the oxygen is set free in the nascent state, a condition under whicli its oxidizing powers are exhibited in their greatest intensity. This powerful affinity of chlorin for hydrogen enables it to decompose many other livdrog-en-containing: molecules in a similar manner, form- ing chlorhydric acid and destroying the identity of the matter acted upon. It has been shown that all organic compounds which are the products of the vital processes of the animal body, contain hydrogen as an im- portant constituent. This applies also to the dccom]>osition products whose presence in the tubular structure of the dentin is the cause of tooth discoloration. These organic stains exhil)it the property of color by virtue of TOOTH-BLEACHING—USE OF CHLOBIN. 427 certain definite conditions of molecular composition ; hence, if chlorin is caused to act upon the coloring matter which causes the staining of a tooth, by seizing upon and combining with the hydrogen of the organic pigment, the identity of the compound as such is destroyed, and its characteristic feature, that of color, is lost. The principle here outlined is involved in what is termed the direct action of chlorin in bleaching. There is, however, another method by which chlorin is believed to act as a bleacher in which its function is indirect. In some cases it has been observed that chlorin fails to act, except in the presence of moisture, and the rationale of this is that the bleaching under such conditions is effected by nascent oxygen liberated from the water molecule when the chlorin combines with its hydrogen to form chlorhydric acid. That such is the nature of the process in many cases is a reasonable deduction from the behavior of chlorin under analogous conditions where it acts indirectly as an oxidizing agent. Whatever may be the exact nature of its ultimate action, it is to be borne in mind that its bleaching effect is due solely to the alteration which it makes in the composition of the color molecule, and that it has no solvent power whatever on the organic matter upon which it acts. It changes its characteristics, but does not remove it by solution. It should be also noted in this connection that the chlorin compounds of most of the metallic elements, especially when in dilute solution, are almost colorless as compared with many of the other metallic com- pounds — the oxids and sulfids for example. Hence it is that where stains owe their color to the presence of certain organic compounds with some of the metals, or even where the coloration is due to decom- position products of hemoglobin, the color may readily be discharged by chlorin, but if the iron chlorid thus produced remains in the tooth structure it is gradually decomposed and new combinations of it are liable to occur, which results in a return of the discoloration. All tooth-bleaching methods should aim not only to discharge the color by suitable chemical means, but' should go farther than this and, so far as it may be possible to do so, remove all organic debris from the tubules, for as long as this remains the tendency to a return of the dis- coloration is always a possible and indeed probable menace to the com- plete and permanent success of the operation. Where the tubular contents cannot be successfully removed, the tendency to a return of discoloration may be combated by hermetically sealing their orifices with an impermeable resinous varnish or perma- nently coagulating them. This feature is described more fully in rela- tion to the details of the bleaching procedure. Teeth Suitable for the Bleaching- Operation. — In deciding upon the advisability of attempting the bleaching operation in any given case, 428 DISCOLORED TEETH AXD THEIR TREATMENT. the general conditions which determine the judgment of the operator with respect to all dental operations should govern his course. As all therapeutic and restorative measures in dentistry are a series of compromises with diseased conditions or their sequelae, it is the duty of the operator to capitulate upon the basis of greatest advantage to the patient under all circumstances. Therefore if discoloration of a tooth is practically the only factor in the problem presented by a given case, the effort should be made to restore the organ to its normal condition of color. The same rule should be applied to all cases of discolored teeth in which structural loss by caries or fracture has not been so great as to preclude a satisfactory restoration by proper filling or replace- ment of the lost structure by a porcelain inlay. The cases in which it is not advisable to attempt a bleaching operation are only those in which loss of structure is so extensive as to require a crowning operation. In the judgment of many operators it is considered useless to at- tempt the bleaching of any teeth excepting the incisors, because of the difficulty and length of time frequently required for the successful bleaching of cuspids, bicuspids, and molars, owing to the thickness of their Avails and the consequent depth of structure requiring treatment. It is also held to be useless to attempt the bleaching of teeth which have been discolored bv metallic stains throuohout their structure. The fallacy of such a view is self-evident when it is considered that if any portion of the dentinal structure of a discolored tooth is amenable to the bleaching treatment, its complete restoration is simply a question of continuance or repetition of the operation until the desired end is attained. With regard to discoloration by metallic stains, while teeth so af- fected present problems of great complexity, and require not only special study but the application of special methods of treatment based upon proper recognition of the chemical relationships involved between the nature of the stain and that of the agent used for its removal, the attempt should be made in justice to the patient, even though ultimate failure result, in order that the necessity for destruction of the natural crown for the purpose of its replacement by an artificial substitute may, if possible, be postponed for as long a period as may be attainable. Preparation of the Tooth for the Operation of Bleaching. — Cer- tain general details are necessary to be observed in the preparation of teeth for the bleaching operation, whatever may be the method of treat- ment employed. Ap]n-o])riate treatment for the removal of all septic matter from the pulp chamber and canal, and for the relief of any existing condition of irritation of the pericemental membrane and tissues of the apical region, should have been carried out and the tooth brought to the condition in TOOTH-BLEACHING— USE OF CHLORIN. 429 which permanent closure of the apical foramen of the root may be safely performed. The rubber clam should be adjusted with esjjecial care and only include the tooth to be bleached. If two adjoining teeth are to be bleached they may both be isolated by the dam, but in no case should one or more adjacent normal teeth be included with the tooth to be bleached. While the inclusion of teeth adjacent to the one which is the subject of any ordinary dental operation is in nearly all cases desirable, there are good reasons why such a plan should not be pursued in the bleaching procedure. The chemicals used for the purpose may possibly have some disintegrating or solvent action upon the enamel structure, and such action, should it occur, should be confined strictly to the tooth undergoing treatment and held within the limits of safety by close observation and appropriate treatment, which conditions cannot be as thoroughly controlled and the process as satisfactorily managed when several teeth are included within the territory of operation. Furthermore, as nearly all of the bleaching agents used or those which are employed as adjuvants in the process have a more or less irritative or escharotic effect upon the soft tissues of the mouth, extra precautions must be taken, in adjusting the dam, against leakage at its attachment to the cervix of the tooth. As the chances of leakage are greatly multiplied when several holes are punched in the dam for ad- justment to as many teeth, it is for this reason also that no other than the tooth to be treated should have the dam adjusted to it. Supposing the tooth to be an upper incisor, the dam should be slipped over it and the margin of rubber encircling the cervix should be gently carried under the free margin of the gum either by means of a small flat burnisher of suitable angle and curvature, or by means of a waxed floss-silk thread. One or two turns of a ligature should then be thrown around the cervix below the dam to hold it securely in place. The dam may be fixed with greater security, especially as against any accidental traction made upon it during the operation, by fastening it with a ligature made as follows and thrown around its cervix : A piece of waxed ligature silk about eighteen inches in length has a large knot tied at about its middle portion by making six or eight turns of the thread loosely around the end of the index finger of the left hand. Upon withdrawing the finger a series of loops are had iihrough which one of the free ends of the thread is now ])assed, as in making the first half of a flat knot, as illustrated in Fig. 387. By drawing upon the free ends of the thread until all of the loops are closed upon themselves, a hard knot of more or less spheroidal shape is formed about midway between the ends of the ligature. The ligature so prepared is placed around the tooth in such a manner that 430 DISCOLORED TEETH AND THEIR TREATMENT. the knot as described shall be located ii])on and at the middle portion of the palatal cervical margin. A half knot is then made by tying the ligature in front so that it shall rest directly opposite the palatal knot, viz. at the middle portion of the labial cervical margin. The ligature is drawn into fairly close contact with the tooth, and, with both ends held firmly in the left hand and drawn somewhat tense, the portion encircling the tooth is firmly but gently forced up against the rubber Fig. 387. dam and gingival margin, the ligature at the same time being drawn tightly until the anatomical constriction of the tooth at its cervix will serve to hold it from slip])ing downward, especially upon the palatal aspect of the tooth. When the ligature is found to be securely placed as described, the knot upon the labial aspect is completed and further enlarged in bulk by re-tying the thread four or five times. The free ends of the ligature should then be cut off close to the knot. As an additional safeguard against leakage of irritating bleaching agents through the cervical attachment of the dam, and out upon the soft tissues, it is well after making the tooth perfectly dry to paint the ligature and a narrow band of its adjacent territory with chloro-percha, which will effectually prevent any accident from leakage. The placing of a large knot upon the palatal aspect at the cervical margin has another decided advantage in that it not only holds the dam more securely against slipping downward, but holds it away from the palatal surface, which is ordinarily the point of entrance to the pulp chamber and canals in these cases. The point of canal entrance may, however, be through an appnjximal cavity, if such an one affords sufficient access. The canal filling in all cases of bleaching without exception should be gutta-percha. No other material used for canal filling possesses the generally desirable qualities needed for that purpose in this class of cases. The extent of the canal filling should include one-third, or at least not over one-half, of the distance from the apex. A considerable portion of the canal beyond the level of the gingival margin is thus left unfilled in order that the coronal end of the root may be bleached as well as the tooth crown. This is especially necessary where more or less recession of the gum from its normal attachment has occurred,, TOOTH-BLEACHING— USE OF CHLORIN. 431 leaving the cervical cementum exposed to the action of the oral fluids, food, etc., which have a tendency to cause discoloration of the exposed root tissue. The root being filled as directed, all fillings wherever existent in the tooth should be removed. This is a preliminary procedure which should not be omitted in any case, but where any bleaching method is used which involves the employment of chlorin as the active agent it becomes imperatively necessary foiy reasons which are explained in con- nection with the description of the chlorin methods (page 432). Aside from other considerations, the removal of all fillings preparatory to the bleaching operation has a decided value in facilitating the process by ex- posing an increased area of the dentinal structure and thereby permit- ting the action of the bleaching agent over a larger territory of ingress. When all fillings or softened tooth structure have been removed, as well as all septic and extraneous matter of whatever character, by^ mechanical process, the tooth should be washed thoroughly with dilute ammonia water, or better with a hot solution of borax in distilled water in the proportion of 3j to fgj. The object of this treatment is to re- move by saponification and solution all fatty matters which may obstruct the ingress of the bleaching agent into the dentinal structure. In nearly all cases where discoloration has occurred from a decom- posed pulp and where the canals and pulp chamber have been left untreated, there will be observed in opening into such a pulp chamber for the first time, a dark oily or greasy layer of material lining the walls of the pulp chamber. The thorough removal of this dark layer should be eifected prior to any attempt at bleaching, as it appears to prevent the ingress of the bleaching agent into the dentinal structure. The most satisfactory method for removing the dark greasy layer is by the use of suitable instruments — either properly shaped spoon or hoe ex- cavators or round burs in the engine. The thorough removal of this layer necessitates free access to the pulp chamber, which should be as a general rule obtained by means of an ample opening upon the lingual aspect of the tooth in the case of incisors, and through the morsal surface in bicuspids, etc. Having by mechanical means and through the agency of borax or ammonia and hot distilled water eifected a thorough cleansing of the interior portion of the tooth, it should next be dried to the extent of having all superfluous moisture removed, and it will then be in condi- tion for the application of whatever method of bleaching may be chosen for the particular case in hand. Dr. James Truman's Method. — This, as before stated, was the first method successfully employed for bleaching teeth. It consists in liberat- ing chlorin from ordinary chlorinated lime by means of a weak acid 432 DISCOLORED TEETH AXD THEIR TREATMENT. in the pulp chamber of the tooth. Any acid will effect the liberation of chlorin from the bleaching powder, but acetic, tartaric, or oxalic are generally used. Care must be observed in selecting a good quality of bleaching powder, as that substance rapidly undergoes decomposition spontaneously, especially in a moist atmosphere. Good chlorinated lime is a drv powder having a strong odor of chlorin. If it is moist or pasty and has but a feeble odor it should be rejected as worthless. Brands of bleaching powder dispensed in metallic packages should not be used, as thev are invariably contaminated with metallic ehlorids due to the slow action of the contents upon the containing package. This is par- ticularly the case where sheet-iron boxes are used. The return of dis- coloration in many cases after bleaching by the Truman method is undoubtedly due to the use of bleaching powder so contaminated. The powder dispensed in glass bottles or in paraffined paper cartons is more reliable. Its application to the tooth may be effected in several ways : (a) By packing the dry powder in the pulp chamber and then moist- ening the latter with the acid ; (6) By mixing the powder Avith sufficient distilled water to make a coherent mass Avhich is more easily manipulated, then packing it in the pulp chamber and aj^plying the acid ; (c) By first moistening the interior of the tooth with the acid, next dipping the instrument into the powder and then into the acid, each time carrpng the mixed materials into the tooth until the desired change of color is produced. Probably the most satisfactory method is to pack the dry powder into the tooth and apply the acid to it, after which immediately seal the cavity with a single pellet of gutta-percha. By using a 50 per cent, solution of acetic acid the evolution of chlorin will take place with a satisfactory degree of uniformity, and not so rapidly as to interfere with its penetration throughout the discolored tubular structure of the dentin. The bleaching mass may be sealed in place by means of oxyphosphate of zinc if desired, but it is usually unnecessary to use anything other than gutta-percha or one of the soft temporary stopping materials for this [)urpose. The case may be dismissed for one or two days and the treatment as outlined repeated at similar intervals until it is restored to normal color. The instruments used in connection with this ])rocess should be of vulcanite, ])one, ivory or wood. Upon no consideration should steel, gold, or ]>latinum instruments be used, as chlorin acts directly upon each of these metals, forming soluble ehlorids which if carried into the tooth structure will give rise to a })ermanent staining of most intract- able character. The onlv metals which mav be safelv used in connec- TOOTH-BLEACHIXG—USE OF CHLOBIX. 433 tion with anv chlorin process of bleaching are zinc and aluminum, the chlorids of which are colorless. Aluminum instruments for the purpose may be quickly improvised out of wire or heavy plate. Gold instruments have been recommended, but they are open to the very grave oljjection of forming a chlorid by direct combination Avith chlorin, which salt is one of the most important staining media known to the histologist ; as a matter of fact the writer has seen several cases where a permanent purple staining of the tooth has resulted from neglect to remove gold fillings before applying the chlorin method of Ijleaching, and there is certainly no reason why the same result should not follow the using of gold instruments in the same connection. "When the tooth has been restored to its proper color it should be thoroughly washed ^dth very hot distilled water, dried out with bibu- lous paper and thoroughly desiccated with a current of dry hot air, after which the canals, pulp chamber, and cavities should be filled with oxychlorid of zinc. The final filling of the cavities of entrance and of decay should be postponed until by a lapse of considerable time the permanence of the operation has been established. This probationary jjeriod may with advantage be prolonged to four or six months. The final washing of the tooth with hot distilled water previous to the insertion of the oxychlorid of zinc filling is a feature of the opera- tion Avhich requires special care and attention. As left after the appli- cation of the bleaching agent, the pulp chamber and canals and denti- nal structure are filled with free chlorin in solution, calcium acetate, or other salt of calcium depending upon the nature of the acid used in the process, and some undecomposed bleaching powder. These sub- stances should be thoroughly removed by the hot-water douche. At least a pint of water should be strongly injected into the interior of the tooth hy means of a large bulb syringe, before the dam is removed. A towel held in close proximity to the tooth will catch the M'ater as it re- turns from the tooth and protect the clothing of the ])atient. Distilled water should in all cases be used for this irrigating douche, as river water and many other specimens of "water from natural sources contain iron in solution, which could readily become a contaminating factor leading to subsequent return of discoloration. Oxychlorid of zinc is selected as the permanent filling for the pulp chamber for the reason that it is necessary to so act upon the l)leached organic residuum in the tubular structure as to prevent any alteration of its character which may result in the production of a subsequent coloration. Zinc chlorid possesses the property of converting many organic substances into unalterable compounds by its coagulant action, thus tanning or mummifying animal tissue and preserving it indefi- 28 434 DISCOLORED TEETH AND THEIR TREATMENT. nitely. A mass of oxychlorid of zinc, before it sets, i. e. before chemical combination takes place bet\veen the oxid-of-zinc powder and the zinc chlorid liquid, is functionally free zinc chlorid — and as a matter of fact the properties of zinc chlorid are manifested by such a mass for a con- siderable period of time after the mass has apparently set. When introduced into the pulp chamber and canal, its action upon the organic debris in the tubuli is as stated, and the material, if the operation has been successfully performed, is effectually prevented from further alter- ation, upon which condition the permanence of the operation depends. Another method for preventing subsequent alteration of the bleached organic debris in the tubular structure is to thoroughly desiccate the tooth by means of the hot-air blast and saturate the dentin with some insoluble resinous varnish, such as copal ether varnish, or what is still better the solution of trinitrocellulose in methyl alcohol, known in com- merce as " kristaline " or at the dental depots as " cavitine." The pulp chamber and canals may then be filled with any suitable filling. As between the oxychlorid of zinc filling and the varnish lining the choice in general should be of the former. The varnish lining is adapt- able more especially to cases of long standing where complete liquefac- tion of the tubular contents has left them practically empty, and where as a consequence there is nothing upon which zinc chlorid can exert its coagulating effect. Other Chlorin Methods. — The solution of chlorinated soda known as Labarraque's solution, or Liquor sodse chloratfe U. S. P., may be applied to the previously desiccated tooth structure until the dentin is saturated with the solution, after which an application of a dilute acid is made which liberates chlorin. The chemical principles in- volved are exactly analogous to those upon which the method with bleaching powder depends, the only difference being that the source of the active agent, chlorin, is in one case its calcium compound, which is a dry j)owder, and in the second case the analogous soluble sodium compound of chlorin is the material from which the active agent is evolved. The precautions necessary to be observed are exactly the same as those required in Truman's method already described. The results obtained by this process are not as thorough or as satisfactory as by the Truman method. Chlorin per se has been used for tooth-bleaching, and was the basis of a method devised by Dr. E. P. Wright of Richmond, Ya. Wright's method involved the use of a complicated apparatus by which a glass vessel of about a half-liter capacity, and filled with chlorin previously prepared in the laboratory, was connected by means of a doubly perforated rubber stopper and two pieces of rubber tubing with BLEACHING BY HYDROGEN DIOXID. 435 a glass adapter, around the open end of which was tied the rubber dam encircling the tooth to be operated upon. About midway of the length of one of the rubber tubes connecting the chlorin reservoir with the rubber dam was interposed an ordinary syringe bulb, so arranged with hard-rubber valves that by repeatedly compressing and relaxing it the chlorin would be drawn from the reservoir and injected through a glass delivery jet into the pulp chamber. Return of the gas to the reservoir was provided for by the second piece of rubber tubing first alluded to. In this way a continuous jet of chlorin was thrown into and about the tooth, which, by means of the rubber dam, was placed in a close cham- ber forming a part of the apparatus ; none of the gas could escape into the surrounding atmosphere. The complexity of the apparatus was a formidable obstacle to the general use of the method and it was abandoned, though the results were in many cases very satisfactory. The Dioxid Bleaching Methods. Bleaching by Means of the Dioxid of Hydrogen and the Dioxid of Sodium. — The commercial introduction of solutions of hydrogen dioxid marked a new era in the operation of bleaching discolored teeth. The bleaching property of hydrogen dioxid had been known to chemists for many years, but the application of this property to tooth-bleaching dates from the medicinal use of hydrogen dioxid solutions for the treat- ment of purulent conditions of the pulp canal and about the roots of teeth. When applied in the canals of discolored and infected teeth it was observed that a noticeable bleaching of the discolored structure resulted. The hint thus given was further studied until it was found that under proper conditions the whole structure of a discolored tooth might be successfully restored to normal color. The earlier preparations were found to be lacking in strength ; aqueous solutions containing more than 3 or 4 per cent, of absolute hydrogen dioxid w^ere found to be too unstable to keep for any length of time, and hence were unreliable. The problem of securing a stable high-percentage solution of the dioxid was solved by using ether as a menstruum, and the 25 per cent, solution of hydrogen dioxid made by McKesson & Robbins of New York and sold as " caustic pyrozone " is now generally used Avhere hydrogen dioxid is employed as a bleaching agent in connection with discolored tooth structure. Hydrogen dioxid, H^02, belongs to the class of " oxidizing bleach- ers," and owes its activity in this respect to the weak state of chemical combination in which one of its atoms of oxygen is bound to the water molecule. Many substances serve to disrupt the compound and liber- ate one of its oxygen atoms. In contact with pus, blood, inspissated mucus, albumin, and in fact almost every kind of dead organic matter, 436 DISCOLORED TEETH AND THEIR TREATMENT. its decomposition takes place, evolving oxygen and decomposing the organic matter either wholly or in ])art. In bleaching discolored teeth with hydrogen dioxid the ethereal 25 per cent, solution known as pyrozone is directly applied to the internal portions of the tooth upon small pledgets of cotton or cotton wisps rolled upon a fine flexible canal instrument. After each application the ethereal menstruum is evaporated by blasts of warmed air from a hot-air syringe, and the applications similarly made are repeated until the desired eifect is produced. It has been found in practice that more rapid and permanent effects are produced when the pyrozone solution is rendered alkaline. This may be readily done by the addition of a few drops of liquor ammonife fortior or by a solution of one of the caustic alkalies, e. g. sodium or potassium hydroxid or sodium dioxid. A very satisfactory method of securing the alkaline effect in tliis pro- cess is that suggested by Dr. D. N. McQuillen. His method is to first treat the pulj) chamber and canals with applications of Schreier's Kalium-natrium pre})aration and after the debris from its action has been mechanically removed Avith instruments and cotton twists, with- out washing the canal, an application of pyrozone is made. The bleaching action follows with great rapidity, and has apparently greater permanence than where the pyrozone is used alone. In cases where the action proceeds very slowly, for example when at the end of a thirty minutes' continuous treatment the bleaching is not complete, it is well to seal an application of pyrozone upon cotton in the canal and allow it to remain for twenty-four hours, when a second treatnu'ut will usually complete the operation. In this as in all bleaching operations it is advisable to fill the tooth teni|)orarily with some easily removable filling in order to test tlie per- manence of tlie operation, and after the lapse of a reasonable time if there is no tendency to a return of the discoloration the canals and cavity may be permanently filled. Dr. Harlan's method consists in acting upon hydrogen dioxid by aluminum chlorid. The aluminum salt is packed in the cavity and moistened witli the dioxid. The technique of the procedure is the same as for tlie methods already described. This process was origin- ally classified with the chlorin methcjds, as the decomposition was sup- posed to take place according to tlie fi)ll()wing equatiou : K\C\ + 3HA = AlA + 3H,0 J-6C1. More recent experimental study of the reaction between aluminum chlorid and hydrogen di(>xid devcl()i)ed the fact that oxygen and not chlorin was given off", and that the aluminum cliluiid was unaltered THE SODIUM DIOXID METHOD. 437 during the process. Hence it was discovered that the reaction was simply due to a catalytic action of the aluminum salt (a property which in this relation it shares in common with many other metallic salts), whereby nascent oxygen is liberated from the hydrogen dioxid. The process, therefore, has no greater value than those in which hydro- gen dioxid is directly applied. The aluminum chlorid being an active coagulant is contraindicated as a factor in the bleaching process until a point has been reached where a coagulant is needed as a fixative after the bleaching has been effected. The Sodium Dioxid Method. — Sodium dioxid, NajO^, is the chem- ical analogue of hydrogen dioxid, and like the latter is characterized by the readiness with which it parts with its atom of loosely com- bined oxygen under similar circumstances. The essential difference in its properties is the character of its by-product after its decomposition has taken place. Itself a strong caustic alkali, it still retains its alka- line and caustic properties after the loss of one of its atoms of oxygen, becoming Na20, which in combination with water is ordinary sodium hydroxid or caustic soda. This substance as well as the sodium dioxid has not only a saponifying property for all of the vegetable and animal oils and fats, but also a solvent action upon animal tissue. This property is of great value in removing from the dentin structure all of the con- tained organic matter, whether normal or in a state of decomposition. Having the oxidizing and consequently the bleaching quality in addi- tion to its solvent and saponifying properties it is, therefore, one of the most valuable bleaching and detergent agents at our command. The substance is dispensed as a yellowish white powder in tin cans or glass bottles hermetically sealed, as it is very hygroscopic and after twenty-four hours' exposure to moist air absorbs nearly its own weight of water ; it also loses much of its activity. For use as a bleaching agent it is applied to the dentin in saturated solution. In making the solution especial care is necessary in order to avoid elevation of temperature, by reason of the energy with which it enters into combination with the water. If the solution is allowed to become heated in the making, decomposition of the compound with loss of oxygen occurs and its bleaching power is destroyed. The solution is best made by pouring into a small beaker of about one ounce capacity about two drachms of distilled water, and immersing the beaker in a larger vessel or dish containing ice-water or pounded ice. The can containing the dioxid powder should then have its lid per- forated with a number of small holes similar to the lid of a pepper caster, and the powder be slowly dusted into the distilled water in the small beaker. The powder is added to the water until the solution as- sumes a semi-opaque appearance, indicating the point of saturation. 438 DISCOLORED TEETH AXD THEIR TREATMENT. On removing the beaker from the cooling mixture, the dioxid solution will in a few minutes assume a transparent, straw-colored appearance and is ready for use. The applications are to be made similarly to the hydrogen dioxid applications, but upon asbestos fiber instead of cotton, as the latter is acted upon bv the sodium dioxid and converted into a glue-like mate- rial, amvloid, which is difficult to remove and interferes with the suc- cess of the operation. After the dentin, which should have been previously desiccated, is thoroughly saturated with the dioxid solution an application of 1 per cent, sulfuric acid should be made, which neutralizes the strong alkali, forming sodium sulfate and hydrogen dioxid, thus : NaP, + H2SO, = Na^SO, -r H^O The reaction is usually attended with some effervescence, which taking place in the tubular structure of the dentin, mechanically forces out its contents and thus exerts a detergent action upon it. The tooth should now l)e washed with hot distilled water in copious quantity and the dioxid application repeated, omitting the subsequent treatment with acid but washing again thoroughly with the hot water. The sodium dioxid method removes more completely than any other the tubular contents, and the result is unique from the fact that not only is the tooth restored to normal color but to normal translucency ; the oi)aque white effect resulting from other methods of bleaching is due to the bleached organic debris remaining in the tubuli, but by the solvent action of the strong caustic alkali this is removed. The final treatment of the tooth is the same in this as in other methods, though the dentin should be desiccated and saturated as thoroughly as possible with an unalterable varnish before the final filling is inserted. The Sulfurous Acid Method. — Reference has already been made to sulfurous acid as the single example of the reducing type of bleach- ing agent. Its activity is due to its affinity for oxygen, and it bleaches by seizing upon and combining with this element of the color molecule, thus destroying its identity and consequently its color. Attemj)ts have been made to utilize the bleaching property of sulfurous acid in the treatment of discolored teeth by direct ap])lications of the solution of the gas in water and by igniting small quantities of sulfur in the root canal by means of the electro-cautery wire. These methods have, however, proved inefficient. The gas may be successfully used in bleaching teeth by evolving it from its compounds placed in the cavity and root canal in a manner analogous to that employed in the Truman chlorin process CATAPHORIC BLEACHING OF TEETH. 439 already described. For this purpose the writer's method may be con- veniently employed : 100 grains of sodium sulfite and 70 grains of boric acid are separately desiccated and afterward ground together in a warm dry mortar. The powder is then to be transferred to a tightlv stoppered bottle. For bleaching purposes the powder is packed into the root canal and cavity of the tooth, and then moistened with a drop of water and the cavity immediately closed as tightly as possible M'ith a stopping of gutta-percha previously prepared and warmed. A reaction ensues between the boric acid and sodium sulfite whereby sulfurous acid is liberated, thus : 2H3BO3 + 3:NXS03= 2^XB03+ 3H,0 +3SO2. The process is effective in many cases where the chlorin methods have failed, but is slow in its action and is largely superseded by the dioxid- of-hydrogen and dioxid-of-sodium methods. Cataphoric Bleaching of Teeth. Since the revival of interest in cataphoresis and its application to dental operations its possibilities as an adjuvant in the tooth-bleaching process are being investigated with much promise of valuable results. It has been found that aqueous solutions of hydrogen dioxid may be car- ried into the dentinal structure with great ease by the cataphoric action of the continuous current. The appliances necessary for tooth-bleaching operations by this means are practically the same as those recpiired in the treatment of hypersensitive dentin, and are detailed at length in the chapter dealing with that subject (page 108j. The resistance offered by the hard structures of the tooth is much greater after loss of the tooth pulp, requiring a much higher voltage pressure to drive the bleaching agent into the tissue. While in some cases 25 to 30 volts will be all that is necessary, some cases will recj[uire as high as 60 volts to carry 1^ milliamperes of current through the dentin. The ethereal solution of hydrogen dioxid has been found to oppose too great resistance to the current, but the aqueous solution containing a slight addition of some salt to increase its conductivity is entirely manageable. A 25 per cent, aqueous solution of hydrogen dioxid may be cjuiekly made by shaking together in a test tube one volume of water and two volumes of 25 per cent, pyrozone. The HjO^ dissolves in the water, and the ether of the pyrozone may be removed by pouring the mixture into a small evaporating dish of porcelain or glass and gently heating it over a water bath until all of the ether has evaporated. The addition of a small quantity of sodium acetate or sulfate will greatly diminish the resistance of the solution to the passage of the current. 440 DISCOLORED TEETH AND THEIR TREATMENT. With the tooth isolated by the rubber dam, as already described in detail, the aqueous solution of HoO, is dropped upon cotton within the tooth cavity and a platinum needle anode is applied in contact with it. The cathode may be a sponge electrode moistened with salt solution and held in the hand or applied to the cheek or neck. The hand, however, is preferable because of the amount of voltage required in the operation. Great care must be exercised that the external surfaces of the tooth are kept dry so that short-circuiting of the current may not take place. In some cases a more rapid effect is obtained by making contact of the cathode pole through a needle electrode upon the external surface of the tooth, and with the anode applied to the pyrozone solution on cotton within the tooth. The cotton must at all times be kept wet with the solution. Dr. M. W. Hollingsworth has devised an ingenious anode for feed- inir the bleaching solution or other medicament into the cavitv as de- sired. The instrument (Fig. 85) is described in Chapter V., p. 124. Another device by Dr. Hollingsworth is of especial value, as it makes possible the enveloping of the entire tooth with the bleaching fluid in which it is immersed as in a bath. The appliance is shown in Fig. 388. Dr. Holliiiffsworth's device for applying the bleaching agent to the tooth. situ in Fig. 388, and consists of a thin vulcanized caoutchouc bulb shaped like the bulb of a medicine dropper. Through a perforation Fio. 389. at its rounded end made witli the ordinary rul)ber dam punch, the tooth is slipped by mounting the bulb on the applicator (Fig. 389), and CATAPHORIC BLEACHING OF TEETH 441 forcing it over the tooth as though it were a rubber dam. A glass tube is then attached to the open end of the bulb, and to the glass tube is connected a spiral platinum wire electrode (Fig. 390). Before the elec- FiG. 390. Tube electrode. trode is attached the bulb and glass tube are completely filled with the aqueous pyrozone solution by means of a duplex syringe (Fig. 391), the Fig. 391. Duplex syringe. lower and larger bulb of which exhausts the contained air in the appa- ratus and the smaller thumb bulb injects the bleaching solution into the exhausted apparatus. Connection is now made with the source of cur- rent as usual, and the bleaching is very rapidly effected. Dr. Hol- lingsworth recommends the addition of about 1 per cent, of zinc sulfate to the aqueous pyrozone solution, which not only diminishes the resist- ance to the passage of the current, but has a coagulating effect upon the bleached organic matter which gives it translucency and greatly enhances the permanency of the operation. The results obtained by this method are extremely satisfactory. 442 DISCOLORED TEETH ASD THEIR TREATMENT. Bleaching Methods for Special Stains. Pulpless teeth are especially liable to discoloration from external and accidental causes. If decayed and the cavity has remained unfilled for a length of time many substances which find their way into the oral cavitv either as food or as medicine may produce discoloration when absorbed by the tooth through the open cavity walls. MetaUk salts are particularly apt to cause such staining by reaction with the sulfids with which the dentin structure is usually saturated during decomposition of its organic contents. Many of the medica- ments used in pulp-canal treatment or even for hypersensitive dentin may stain the tooth structure, and finally the action of sulfids in the structure of a pulpless tooth may react with amalgam fillings, forming salts of mercury, silver, tin, copper, etc., which are absorbed by the tooth, resulting in its discoloration. The treatment of these stains, which were grouped as Class III. at the beginning of this chapter, is extremely difficult and often unsatisfactory. However, there may arise individual cases of discolorations of this class where it is of the utmost importance to remove them, and much may often be accom- plished when the causes of the discoloration are known and the proper bleaching method is applied. Gold stains may arise, as has been already indicated, from the inju- dicious use of gold instruments or failure to remove all gold fillings when applving some one of the chlorin methods of bleaching. In the course of time where this has happened the tooth assumes a pinkish hue which merges into a characteristic violet or purple, finally becoming black. Iron stains may arise from the use of steel instruments in connection with the chlorin methods of bleaching or in contact with iodin or any of the mineral acids in connection with canal treatment. The iron stain is yellowish at first, gradually becoming bi'own and finally black. Copper and nickel stains may arise from contact with these metals or their alloys, as copper amalgam or nickel or German silver dowels for artificial crowns or anchorages for fillings. The stains from these metals are — for copper, bluish to black, and for nickel a characteristic chlorophyll green which eventually becomes black. The best general treatment for all of the foregoing stains is to re-bleach the tooth by the chlorin method, with especial care as to the .several precautions already recommended, and when the color of the metallic stain has been discharged by conversion of the dark-colored salt into a soluble chlorid, wash the tooth thoroughly first with dilute chlorin water 50 ])er cent., and afterward with hot distilled water to remove all of the metallic chlorid which has been formed. The process may require repetition to secure jUTinanent results. BLEACHING METHODS FOR SPECIAL STAINS. 443 Silver stains are comparatively easy to remove, either by an applica- tion of the chlorin method or by saturating the tooth with tincture of ioclin, thus converting the silver salt into a chlorid or iodid as the case may be, after which it may be dissolved out with a saturated solution ■of sodium hyposulfite applied as a bath to the tooth. For this pur- pose the Hollingsworth bulb dam (see Fig. 390) answers admirably, and although the experiment has not as yet been tried, there is good reason to believe that the cataphoric method with electrodes applied in reverse order would under these circumstances greatly facilitate the solution and removal of the metallic salts. Mercurial stains are always black from the formation of mercuric sulfid,and are removable by the same method as are silver stains, with the exception that where the stain has been converted into a chlorid by the chlorin method, the mercuric chlorid is best removed by an aqueous ammoniacal solution of hydrogen dioxid, or when the stain has been converted into mercuric iodid by the use of a saturated solu- tion of potassium iodid. In both cases a final washing with hot dis- tilled water is a sine qua non. Manganese stains frequently occur from the use of potassium per- manganate, in solution or in substance, in the treatment of putrescent canal conditions. The manganese stain is a characteristic mahogany brown. It is very readily removed by a 25 per cent, aqueous solution of hydrogen dioxid in which oxalic acid crystals have been dissolved to saturation. A few applications of this mixture will quickly de- colorize the stain, after which a liberal treatment of hot distilled Avater is required as in the foregoing cases. In all cases a careful diagnosis of the chemical nature of the dis- coloration should be made when possible. Much information upon this point may be gained by a detailed study of the present condition of the tooth and its environment, but in addition to this the patient should be questioned as to the history of the case, and especially as to its previous treatment. The data thus obtained should be carefully noted and treat- ment instituted in accordance with the conditions to be met. Success in the bleaching of teeth demands a recognition of the fact that each case presents individual peculiarities, that the problem is essentially a chemical one always, and that the bleaching method in any given case must be selected with especial reference to the character of the discoloration and applied with due care as to its details in order that the chemical requirements of the operation may be intelligently met ; without which care success is impossible. CHAPTER XIX. EXTRACTIOX OF TEETH. By M. H. Cryer, M. D., D. D. S. Indications for the Operation. It is impossible to formulate a set of exact rules by which the prac- titioner may be governed, in deciding upon the extraction of teeth. So many circumstances both local and general must be taken into consid- eration that little more can be done than to suggest the most important causes MJiich demand the operation. Deciduous Teeth. — The indications for extracting deciduous teeth are — First : When the teeth are a source of irritation affecting the gen- eral health or comfort of the child and do not respond to treatment. Second : When the deciduous teeth are preventing the eruption of the permanent teeth into their normal positions. Occasionally a de- ciduous tooth will assist in the proper placing of a permanent one, in which case it should not be removed as long as it is of such use. Third : When a lower permanent incisor shows signs of erupting on the labial side of the deciduous tooth, the latter should be removed at once, but if the erupting tooth appears on the lingual side the removal of the deciduous tooth may in that case be delayed somewhat longer. Fourth : When upper permanent incisors show a tendency to erupt on the palatal side of the temporary teeth, the latter should be extracted, but when they are erupting on the labial side the deciduous teeth may be allowed to remain for a time, as they are often useful in forcing the permanent teeth outwardly. This, however, must l)e closely watched to prevent the permanent incisors from moving too far. Permanent Teeth. — The indications for extraction of the permanent teeth are — First : Diseased roots which cannot be cured and so made useful for crowning, or assisting in retaining a bridge, plate, or other pros- thetic device. 444 INDICATIONS FOB THE OPERATION. 445 Second : Teeth of mastication that have lost their occluding teeth and in consequence thereof are being pushed from their alveoli and are a source of trouble. As a rule, this refers only to the second or third molars, and more particularly to the third molar. When it occurs with other teeth the opposite vacant space should be filled by an artificial tooth to prevent the extrusion of the natural tooth. Third : When incurable abscesses originating from teeth in the upper jaw tend to open into the nasal chamber, maxillary sinus, or zygomatic fossa, the teeth associated with such abscesses should be ex- tracted. When diseased teeth are the exciting cause of an incurable ab- scess in the lower jaw which opens or threatens to open externally on the chin, jaw, or below the bone into or upon the neck, they should be removed. Fourth : Teeth which occupy irregular positions in the arch, that cannot be corrected so as to become useful or contribute to the gen- eral symmetry of the mouth, should be removed. Fifth : Erupting teeth that are retarded because of lack of room in the jaw, if giving pain, should be extracted or else the tooth that is preventing the eruption should be removed. A marked example of this is often found in the eruption of the third molar when all the other teeth are of good size and are in place. These molars when retarded €ause the greatest distress, sometimes producing serious results, and must be extracted if possible, or if they cannot be safely removed the second molar may be extracted, in consequence of which the third molar will usually be erupted near its place. When an upper third molar is erupting under the same circumstances there is usually less difficulty, as having but slight resistance distally it can erupt outwardly or slightly backward, though, should it impinge upon the soft tissues covering the ramus of the lower jaw, it should be extracted. Sixth : Teeth so badly diseased that they will not respond to treat- ment and are a source of discomfort to the patient should be removed, as they impair the general health. Seventh : First molars. There has been much discussion regarding the early extraction of these teeth, many claiming that if the pulp of one becomes devitalized at an early period of life and it is deemed best to extract it, the other three should also be removed. No fixed general rule, however, can be given ; each case must be considered separately. There are cases where the extraction of all is necessary, and others where it would be a most unwise thing: to do. When the anterior teeth are fully in position, the bicuspids occluding correctly with their oc- cluding teeth and the second molars are about to erupt, the case may then be one for extracting the four first molars, provided it be neces- sary to extract one of them, or if it be likely that one or more of them 446 EXTRACTION OF TEETH. will be lost in a few years. If, however, the bicuspids are not in good position it is better not to extract the first molars, as they assist in keep- ing the jaws in position and preventing the lower anterior teeth from biting against the upper gum. Removal of Sound Teeth Preparatory to Inserting- Artificial Dentures. — When preparing the mouth for an artificial denture the removal of sound teeth may be indicated as a measure of expcdi- encv in relation to mechanical and hygienic considerations. For ex- ample : (1) Roots which a plate or bridge would cover, excepting when they assist in holding the device. (2) Teeth from which the gums have receded to such an extent as to become useless or unsightly. (3) Teeth that are being extruded from their alveoli from the ab- sence of occluding teeth. The extraction of these depends, however, on the extent of " elevation " and the possibility of placing occluding artificial teeth in position. (4) Where there is but one tooth remaining, or two teeth standing together, or in certain cases when several isolated teeth remain which cannot be made to contribute to the mechanical adaptation of an arti- ficial denture, extract when in the upper jaw. They interfere with the fitting of an upper plate, l)ut in the lower jaw they may be useful in retaining the plate. (5) When there are two teeth, one on each side of the upper jaw, in good position and desirable shape for clasping, do not extract unless they are the third molars or the oral teeth. ( 6) In preparing the upper jaw when two cuspid teeth alone remain, or when there is also a molar or bicuspid, or both, and it is decided to extract the molars and bicuspids, then extract the two cuspid teeth also. It has been claimed by some of the very best dental practitioners, whose opinions must be respected, that by keeping these teeth the expression of the face is less likelv to be marred. For the following- combined reascms, however, extraction is advised : a. It is very difficult to obtain a correct impression of the mouth while these teeth only are in position. 6. It is nearly impossible to perfectly match, grind, and arrange the lateral incisors beside single cuspids. c. The adhesion of the plate to the mouth is interfered with, as air and food work in between the plate and these natural teeth. d. The plate is very much weakened by being cut out for the accom-^ modation of these teeth at wliat might be termed the abutments of the arch. In the loicer jaw single teeth Mhich are sound are usually of great. INSTRUMENTS AND* ACCESSORIES FOR EXTRACTING. 447 importance. They should not be removed, as they assist in retaining- a denture by means of clasps or other devices. Especially is this true in persons advanced in years, as then the alveolar process is generally much absorbed. If the lower process is much absorbed even an imper- fect tooth will do good service of this character for a time, and if it is the first plate the patient has worn it will serve a good purpose by assisting in the retention of the plate until the patient has become ac- customed to it, after which the tooth, if giving trouble or if it is un- sightly, may be removed and an artificial one placed on the plate. Instruments and Accessories for Extracting. The instruments used in extracting teeth are forceps and elevators of various shapes and sizes. Forceps. — The forceps should be made of steel of the best quality for the purpose obtainable, in order to give great strength and stiffness, and at the same time toughness, so that they will not break. Forceps that will spring or bend destroy the sensitivity of the hand using them in such a way as to prevent the operator from discerning in what di- rection the resistance to extraction is being made. The beaks of the forceps as a general principle should be shaped so as to fit and adjust themselves to as great a surface of the various teeth or roots as pos- sible so that they may take a firm hold. They should be at such an angle in relation to the handles as will permit them to be easily and readily placed in the proper position. The inner surface of each beak should be concave in a transverse section and without serrations, as these are of no assistance but tend to weaken the beaks and are dif- ficult to clean. The edges of the concave portion should be sharp enough to cut through the alveolar process if necessary. The points of the beaks should be sharp and tapering so they can be forced into position. The handles should be of a shape to allow a firm grasp, and as the hands of different operators vary in shape and size, it will be evident that the same size of forceps handles will not be perfectly satisfactory to all. The curvature of the handles should vary accord- ing to the general or special use of the forceps, and should be so shaped as to interfere as little as possible with the view of the tooth and asso- ciated parts. The curved ends, as seen in Fig. 392, are of little use, and should be done away with in all forceps excepting perhaps those made especially for the upper and lower molars. The joints of extracting instruments should be so made that the handles can be separated by some simple mechanism to permit of thorough and easy cleansing. Figs. 392 and 393 represent an instru- ment of this character. There are others of the same nature, but 448 EXTEACTIOX OF TEETH. Fig 392. this being tlie most simple and the strongest should be gen- erally adopted unless a similar device can be adapted to the " knuckle-jointed " instrument. (Fig. 394.) There should be no sharp angles or crevices, and if the ordinary forceps is used, that portion around the joint in a transverse section should be oval. Forceps are often made with octagonal joints, but these should be condemned, as they may not only hurt the lips of the patient, but in case of a slip, which may happen with the best operators, they are more liable to cause injury by striking the other teeth ; moreover they are very clumsy and require more room. Fig. 393. Antiseptic universal lower molar forceps. Joint of an antiseptic lower molar forceps INSTBUiMEXTS AND ACCESSORIES FOR EXTRACTING. 449 Fig. 394. Unless the antiseptic joint (Figs. 392 and 393) is used the union of the joints is usually made upon one of two principles : first, by one half passing into a mortise in the other and held in the centre by a pinion (Fig. 395). The second is known as a knuckle-joint (Fig, 394) made by each portion being let half way into the other and held to- gether by a screw. This is a neater joint and does away with many of the objectionable fea- tures noted in other forms of forceps joint. All handles should be ser- rated as shown in the illustra- tionSj and the instruments if properly cared for need not be nickel-plated. The number of forceps in a practical set will vary with the requirements of every individual who extracts teeth, therefore only the general principles which should govern the selection of a set of instru- ments will be here given ; at the same time the uselessness of a very large selection is here em- phasized. As an illustration of the range of tooth extractions which may be performed with a limited number of instruments the forceps represented by Figs. 395 and 396, showing the exact size, will serve as examples. They are smaller than the ones generally used, especially in America. The instrument shown in Fig. 395 may be used almost universally for the upper teeth. Fig. 396 is a forceps of the same general character as that in Fig. 29 Knuckle-joint root forceps. 450 EXTRACTION OF TEETH. 395, only the beaks are at a different angle to the handles. This pair Fig. 395. Fi«- 39«. l^f^ ■a Universal upper mcisor and root forceps. Universal lower incisor ami root forceps. may be used similarly for the lower teetli. Tliese foree})s are useful iu all cases, except in the full areh, when eitlier a first or second molar is INSTRUMENTS AND ACCESSORIES FOR EXTRACTING. 451 Fig. 397. Fig. 398. m m m m nv\ m. For the ten upper anterior teeth. Root, upper front. Straight. 452 EXTRACTIOy OF TEETH. Fig. :^99 to be extracted. If the teeth are large, the jaw strong, and the line of grinding surfaces concave, it is better to use the special lower molar forceps as shown in Figs. 392 and 404. Fig. 397 and Fig. 398 rep- resent very useful forceps for extracting the ten upper an- terior teeth. Fig. 398 has longer beaks and its points are finer. In skillful hands where too Q-reat a force will not be brought to bear on the points they are the better forceps. Under nitrous oxid and where many teeth are to be extracted, thus requiring I'apid work, the instrument shown in Fig. 397 is preferable. Figs. 399 and 400, right and left, represent forceps s})ecially used for extracting the first and second upper molars on either side. The outer beak is made pointed for the ])urpose of pass- ing in between the l)uccal roots, the inner beak is concave in order to grasj) the palatal root. Figs. 401 and 402 show forceps especially made for extracting the up])er third molars, Fig. 402 l)eing used for up[)er roots. The ends of the handles of all forceps which are forcied in by the palm of the hand should have a broad surface as shown in Fig. 402. Foivepsfor Extracting Lower Teeth.— JnAvixd of the beaks of the forceps l)eing nearly on a line with the handles as in IC1-4IU ui,,H. molar. tliosc for the uppcr jaw they are bent at nearly a right angle. For the incisors of the lower jaw INSTRUMENTS AND ACCESSORIES FOR EXTRACTING. 453 Fi«. 400. there are no better forceps than those shown in Fig. 396. The forceps represented in Fig. 395 can also be vised to advantage for these teeth, the operator standing behind and working over the head of the patient, as shown in Fig. 452. Fig. 403 also exhibits a special instrument. It is made for extracting the loAver cuspid and bicuspid teeth of either side. Fig. 404 is a special instrument used for the lower molars of either side. The beaks are pointed with a convexity on each side of the point to allow it to pass in between the roots. The two concave portions fit against each root. Fig. 405 shows forceps especially designed for the extraction of the lower third molar ; it is useful in some cases. Fig. 406 represents a uni- versal lower root forceps. Elevators or Root Ex- tractors. — There are many kinds of elevators iised in ex- tracting roots. Some are also occasionally used in the ex- traction of teeth (usually the third molar). Fig. 407 shows one of the most useful forms of this in- strument. Fig. 408 represents two scalers, right and left ; they are extremely useful in ex- tracting roots. They are so unlike an extracting instru- Left upper molar. ment that patients do not dread the appearance of them, as they do 454 EXTRACTION OF TEETH. Fig. 401. Fig. 402. m Universal uppti third m ilar Dorr's upper root forceps. INSTRUMENTS AND ACCESSORIES FOR EXTRACTING. 455 1- iG. 403, Fig. 404. rniversal lower cuspids and bicuspids. Universal lower molars, designed by Lir. Chapin A. Harris. that (jf forceps. By carefully inserting the blade with the point toward the root to be removed, between it and the adjoining root ar 456 EXTRACTION OF TEETH. Fig. 405. Fig. 406. Universal lower third molar. Root, lower. Half curved. INSTRUMENTS AND ACCESSORIES FOR EXTRACTING. 457 tooth, and giving a slight rotary motion, the point will force the root from its socket with but little pain. Fig. 408. Fig. 407. |l,l Elevator. Right and left sealers used for extracting roots. Lancets. — Figs. 409 and 410 represent various forms of lancets, the more useful of which are Nos. 1 and 6, which are all that are 458 EXTRACTION OF TEETH. required for lancing in cxtractincj or for relief of retarded eruption of deciduous or other teeth. They are also useful in Fuj. 409. general surgery of the mouth. Fig. 410. sizes, reniov It is ed or Lancets with ebony liandles and with solid steel handles. Scissors. — A good pair of curved scissors, as shown in Fig. 411, should be at hand in case a portion of gum tissue is found to be attached to the root. If the scissors were slightly more curved they would be even better adapted for this purpose. In connection with the instruments already men- tioned, there should be a mouth mirror (Fig. 412), and one or two excavators and probes for general ex- amination of the teeth and especially for examining the position and character of a root or tooth which it is ])roposed to extract. M( )UTH Props. — When an anesthetic is to be given it is advisable to use some kind of a mouth prop, in order to keep the mouth well open. Some operators do not use them, as they may interfere with the giving of the anesthetic by impeding respiration. Fig. 413 illustrates excellent props devised by Dr. Frederick Hewitt of London, England. Thk Mechanical Mouth-opener (Fig. 414). — This instrument is made in various shapes and inserted between the jaws when the props are to be in cases of trismus, and may also be used to separate SURGICAL ANATOMY. 459 Fig. 411. the jaws and retain them so in cases of emergency or during cer- tain operations within the oral cavity. All dentists, and especially those who extract teeth, should have at least one pair of pharyngeal for- ceps (Fig. 415). It is possible that they may never be used, but on the other hand an accident may occur such as a fragment or tooth slip- ping into the pharynx, where if the finger cannot reach it this instru- ment will be absolutely necessary. Surg-ical Anatomy. — To extract teeth successfully it is first neces- sary to be perfectly familiar with the general shapes of the different Fig. 412. Curved scissors. Mouth mirror. teeth and their position in relation to the jaw and to their associates, in order that the operator may intelligently apply the force in the line of the least resistance required for their removal. This knowledge cannot be obtained from books ; they are but the guides to it. The jaws of the dead subject must be dissected — both the cleaned bones and those with the soft tissues left upon them. "Dissection" means that not only shall the superficial relations be studied, but that the bones shall be cut in various directions, both with the saw and other instruments, until the relations of the teeth of the upper jaw with the floor of the nasal chamber and the maxillary sinus are fully understood. In the lower jaw, the relations of the teeth with the inferior dental canal and the 460 EXTRACTION OF TEETH. position of the roots, especially those of the third molar, must also be thoroughly known. Fig. 413. Hewitt's mouth props (half size). The alveolar process of both jaws is made up of two plates, external and internal, consisting of dense compact bone. The interspaces between Fig. 414. Mechanical mouth-opener (half size). these plates form the sockets for the teeth and are surrounded by a very thin cribriform plate of bone. The remaining space is filled with can- FiG. 415. Pharyngeal forceps (half size). ccllated tissue, small bony channels, connective tissue, nerves, vessels, etc. As this process belongs to the teeth, being develo]^ed with them, and is for the purpose of holding tliem in position, it disappears to a SURGICAL ANATOMY. 461 greater or less extent when the teeth are lost. The resorption of this process does not take place alike in each ja^y. In the upper jaw the external j^late disappears more rapidly and to a greater extent than the inner plate ; in the lower jaw the resorption of" the two plates is about ecpial in extent and rate. The inner plate of the upper jaw is partially supported by the external plate of the palatal process, in fact one merges into the other. The outer alveolar plate of the upper jaw being resorbed to a greater extent than the inner one is of advantage to the dentist in fitting teeth to the gums ; consequently, in extrac- tion that fact should be remembered and injury to the internal plate avoided. At the same time it does no harm to remove a small por- tion of the outer plate, though loss of the gum tissue should be avoided if possible. In the lower jaw it is not so important to avoid removing slight portions of the inner plate, as resorption takes place about equally in the two plates. These plates may be resorbed in such a manner that a slight ridge is left between the places which they occupied. This resorption of both plates of the alveolar process of the lower jaw makes it more diffi- cult to fit single plain teeth in the lower than in the upper jaAV. Fig. 416. Alveoli of permanent teeth— upper jaw. Fig. 416 shows the alveoli of the upper denture, Fig. 417 that of the lower. Fig. 418 illustrates a typical upper and lower jaw, the external sur- 462 EXTRACTION OF TEETH. Fig. 417. Alveoli of permanent teeth— lower jaw. Fig. 418. ^■%\- I I I V N- Typical upper and lower jaw. SURGICAL ANATOMY. 463 faces of the crowns of the teeth, also a normal occlusion. Figs. 419 and 420 illustrate the occluding surfaces of the teeth and their rela- tions with each other. They are made from the same skull as Fig. 418. Fig. 419. ^ Showing the occlusal surfaces of the upper teeth. (From same skull as Fig. 418.) Fig. 421 is from a photograph taken from the right side of a skull. It gives a good representation of a fairly normal occlusion of the Fig. 420. — ^^/^-^ Showing occlusal surfaces of the lower teeth. (From same skull as Fig. 418.) teeth, their shape, roots, and their relation with the cancellated tissue and the inferior dental canal or cribriform tube of the lower maxilla. 464 EXTR ACTIOS OF TEETH. Fig. 4-Jl. -howing the buccal surfaces of the crowns and roots in position. Fig. 422. Fr'jiu SUBGICA L AXA TO MY. 465 In the upper jaw the boue is thin over the position of the molar teeth, and their roots are comparatively straight ; none of these should be difficult to extract. The buccal roots of the first molar are somewhat divergent from each other. The same roots of the second molar spread only slightly as they leave the crown and close in at the points. The Fig. 423. Hs Mec T A's Hp HSy Hiatus semilunaris; J/ec, middle ethmoidal cells; CI, crystalline lenses: Cp, uncinate pro- cess; Mt, middle turbinated bone; Mm, middle meatus; Ms. maxillary sinus; Im, inferior meatus ; It, inferior turbinated bone ; Vm, vestibule of mouth; 1st M, first molar; Dis. r. Ut M, distal root first molar; Idn, inferior dental nerve; T, tongue; Ns, nasal septum; Hp, hard palate. roots of the third molar are together and slightly curved backward. In the lower jaw the roots are comparatively straight. Those of the first molar are spread only a little apart, this being the usual condition. The roots of the second molar are almost straight and are nearly parallel with each other. The anterior root of the third molar curves slightly backward until it joins the posterior root. rio<. 422 is taken from the left side of the same jaw as Fig. 421. In Fig. 421 the roots have been exposed down to their apices ; in Fig. 422 only the external or cortical plate has been removed. These two illus- 30 466 EXTRACTION OF TEETH. trations give a correct idea of the relations of the teeth to the internal structures of the jaw. Figs. 423 and 424 are good illustrations of the relations of the roots Oms - , 0ms 0ms, Opening maxillary sinus ; Ist M, first molar. with the floor of the maxillary sinus. It will be noticed that the roots of the molars pass up on both sides of the sinus, and because of this fact in extracting teeth from a jaw of this character it is necessary to use Fio. 425. Ar 1st M, Anterior root of tirst laolur; li :2d HI, ritol iif sccoiul bicusijid ; Idn, inforior dental nerve ; U, U-shaped or cortical portion of lower jaw. the greatest caution, otherwise a portion of the floor of that cavity might also be removed. Or if a tooth l)e broken and much upward force used in endeavoring to take hold of the root, the root could easily be forced into the sinus. The lower portion of Fig. 423 gives a general idea SURGICAL ANATOMY. 457 of a transverse section of the lower jaw made posterior to the mental foramen. Especial attention is drawn to the U-shaped formation of the cortical portion of the lower jaw which terminates in the two plates of the alveolar process, and between which the roots are imbedded in the cancellated tissue. It also shows how the roots extend toward the mterior dental nerve. Fig. 425 shows the relation, length, and position of the second bicus- ¥iG. 426. pid, showing that its root is sometimes placed to the inner side of the anterior root of the first molar. The roots of these bicuspids are flat, as will be seen by looking at Fig. 440. On taking into consideration their length, position, and thinness it will be readily seen why it is so often difficult to extract them without breaking. Fig. 426 is taken from horizontal sections of the lower and upper 468 EXTRACTION OF TEETH. jaws, showing the transverse sections of the roots of the teeth. The section is made a little above the margin of the alveolar process of the upper jaw and a little below in the lower. The illustration shows the shape and position of the various roots, with their relations to the pro- cess and to each other. Particular attention should be ":iven to the fact Fig. 427 Rc Uli Dn, Dental nerve; i? M M, roots of third molar: R '2d M, roots of second molar: R 1st .V. distal root of first molar; R2dBi, root of second bicuspid; R IH Bi, root of first bicuspid; Re, root of cuspid ; Rli, root of right lateral incisor. that the roots and process are in such close relation as to make it im- possible to force the beak of a forceps between them without breaking one or both plates of the process. The lines leading from the roots show the proper direction for applying what is known in extracting as the " out-and-in motion." Fig. 427 rej)resents a horizontal section made through the lower jaw near the ends of tlie roots, and from the same bone as that shown in the lower half of Fig. 42(j. The cancellated portion with the soft tissue filling the spaces can be plainly seen. The nerve ])assing into its tube, the ends of the roots of the second and third molars, the tip of one of the roots of the first molar, and the roots of the first and second bicus- pids are all plainly shown. A litth' of tlie lateral incisor can be noticed, but the centrals do not reach so i'lw down. SURGICAL ANATOMY. 469 Figs. 428 and 429 are taken from a sagittal section of the upper jaw, external to the infraorbital foramen, and through the roots of the Fig. 429. — Om Ifs, Infraorbital sinus ; If, infraorbital foramen ; Pic, piece of paper passing through infraorbital canal ; Ms, maxillary sinus ; Aa, apical abscess. Om, Opening into malar bone ; Ifs, infraorbital sinus. molar teeth. This illustration shows how the roots often extend above the lower portions of the floor of the sinus, an abscess from the palatal root of the first molar having discharged into the floor of the sinus at the point Aa. It has been demonstrated both anatomically and clinically that in- fectious matter from a suppurating tooth may eventually give rise to an inflammation of the meninges of the brain. Should pus from a dento- alveolar abscess discharge into the maxillary sinus it may pass out into the hiatus semilunaris and ascend into the frontal sinus or in the vicin- ity of the cribriform plate of the ethmoid through the infundibulum when the passage through the hiatus into the middle meatus is small or con- stricted, as it usually is when inflamed, or the pus may pass directly through the infundibulum. Recent research has shown that the frontal sinus, the cribriform plate of the ethmoid, and the meninges of the brain are in close relation at the anterior portion of the cribriform plate, a dis- eased condition at which point is liable to involve all three structures. Fig. 430 is from a longitudinal section of the lower jaw, and gives a good idea of the cancellated tissue, the relations of the sockets of the teeth to one another, and the position of the inferior dental canal. Fig. 431 is taken from several transverse sections of a lower jaw. The bone is not quite normal, as several teeth were extracted before 470 EXTRACTION OF TEETH. Fig. 430. Fig. 431. SURGICAL ANATOMY. 471 death, the loss having caused changes in the character of the bone. Some of the sections show but one canal while in others there are many, requiring close observation to tell in which the nerves and vessels have passed. At point d it will be seen that the root of the second molar penetrates the true nerve canal. Fig. 432. Fig. 432 is taken from the inner side of the right half of a lower jaw. The second molar has been broken off, the roots still remaining Fig. 433. in position. The points of the roots of the third molar pass out through the inner wall a considerable distance below the mylo-hyoid ridge. A 472 EXTRACTION OF TEETH. portion of the ridge has been cut away, exposing the remainder of the internal surface of the roots. This will be further alluded to when ex- traction of the lower third molar is considered. Figs. 433 and 434 are from the outer side of the right half of a lower Fig. 434. j:i\\ , Fig, 433 showing an impacted third molar lying horizontally in the jaw. Fig. 434 is of the same jaw with the tooth removed from its bed, showing the inner surface. The second molar is a pulpless tooth the distal root of which shows where the impacted tooth has pressed against it, causing the absorption of a portion of the root and exposing the ]>ulp canal within, producing death of that organ. This must have caused neuralgia. The cancellated tissue of this bone, it will be noticed, is not like that sliown in Fig. 419, the change in the character of this tissue being the result of irritation caused by the impacted tooth. It will be seen that the roots of the other teeth in this jaw are longer than usual, the cuspid tooth passing below the nerve and to the outer side. Figs. 435 and 436 represent the inner side of the left half of a lower jaw. It shows an impacted third molar pointing slightly downward. The distal root of the second molar is slightly absorbed. On uncover- ing the tooth and taking it from its bed, it Avas found to be incased in a thin shell of bone as though the dental sac had ossified separately around this tooth ; this thin incasement of bone may, however, have been an inflammatory product. The inner ])orti()n of this shell can be seen in position. The nerve and its accompanying tissue passes into the infe- rior dental foramen immediately against the shell and has the appear- SURGICAL ANAT03IY. 473 ance of being flattened out. It divides and sends a branch around the internal half of the shell. Fig. 435. WOk. !^ * '^■ Inner side of left half of lower jaw, showing an impacted third molar. Figs. 437 and 438 are taken from the right and left halves of the lower ja\v. Fig. 437 shows the internal surface of the right half; Fig. 436. (Same as Fig. 435. > Fig. 438, the external surface of the same. In Fig. 437 the roots of the third molar curve backward, are joined together, and are so 474 EXTRACTION OF TEETH. enlarged by an abnormal deposit of cementum caused by continued hyperemia due to the prolonged irritation that the form of each root is lost ; the bone also is much thickened. Fig. 438 shows an impacted Fig. 437. Right half of Inwer jaw. tooth pressing directly against the one in front of it, the roots of which have become much enlarged by the deposit of cementum. The sur- rftunding; bone is also thickened and much more com})act than the nor- mal bone. The character of the cancellated tissue of the lower jaw is lost by the deposit of bone caused by continued irritation of that tissue. Fig. 438. Ltjft lialf of lower jaw. Figs. 4;i9 and 440 show the normal forms of the teeth, and Fig. 441 is taken from a group of abnormal teeth. If only normal conditions of the teeth had to be considered, as shown in Figs. 439 and 440, ex- S URGICAL ANA TOMY. 475 traction would be a very simple operation, but unfortunately this is seldom the case. It often happens that even when the teeth them- selves are normal they are situated in abnormal positions, and for this Fig. 439. Deciduous teeth — left side (Burchard). reason alone their extraction becomes necessary. In fact, so varied and complicated are the different abnormalities presented that it would be impossible to describe them all. The diagnosis of unerupted teeth occu- FiG. 440. Permanent teeth — right side (Burchard). pying abnormal positions has been greatly facilitated by special applica- tions of the newly discovered skiagraphic method. Its general use in this connection is but a question of time and further development. A careful study of the comjjlications most frequently occurring will, how- ever, give good preparation for meeting the emergencies. Figs. 432, 433, 434, 435, 436, 437, 438, and 442 show abnormal positions of various teeth. It will be readily seen that no set of rules 476 EXTRACTION OF TEETH. Fig. 441. H AVjiiorraalities in teetli. could l)e made to govern the extraction of these teeth ; tlierefore only the general principles governing extraction can be here set forth. General Principles in Extracting Teeth. These principles may l>e classified under the following heads : (1) Management and Position of Patients. (2) .Selection of Instruments. (3) Techni(|ue of the Operation. GENERAL PRINCIPLES. 477 Management of Patients. — The first important step toward a suc- cessful operation in dentistry is to gain the confidence of the patient, who must be brought to rely entirely on the judgment and skill of the Fig. 442. Abnormal jaw showing impacted cuspids operator. If the operator feels entire confidence in his own ability' to successfully carry out an operation he can, by his manner of approaching the patient, impart a feeling of almost absolute trust in his skill. This feeling of confidence in himself should be cultiyated, as it is evident that a slight neryousness on his part, even though he be most skillful, will tend to alarm the patient to such an extent as may cause great interference with the operation. Position of the Patient. — The principal object to secure in placing the patient is to obtain a good view of the affected tooth and contiguous parts ; after which the position should be made as comfort- able as possible both for the patient and operator, taking care that the territory of operation can be reached with but little strain or effort. The position both of patient and operator varies slightly for the extraction of each tooth. The main points to be observed are to have the particular tooth to be operated upon in view, and the head of the pa- tient in such a position that it can be controlled by the left arm and hand. The chair should be steady, strong, and comfortable, with arms and a good head-rest of rather a concave shape. It should also have a suit- able foot-rest. When the regular dental chair is not obtainable, an ordinary strong wooden chair can be used. If two of these chairs are placed back to back the extra one gives a good place for the left foot of the operator, and a head-rest may thus be made of his thigh. The patient should be directed to grasp the seat at both sides with his 478 EXTRACTION OF TEETH. hands. At times it may be necessary to extract while the patient is in bed or on an operating: table ; in such cases the operator must obtain the best position available. AMiere an operating table or couch is used it is well, if possible, to stand at the head of the couch or table and a little to one side of the patient. By reacliino; over the head, the for- ceps shown in Fig. 395 may be used to advantage in work on the lower jaw ; the same forceps may be used for the upper jaw by standing to one side of the patient. If the operator is ambidextrous, so much the better, as it is very advantageous to be able to use the instrument in the left hand, especially in extracting the teeth of the right side of the lower jaw. If, however, only the right hand can be used, the operator should, as a rule, stand at the right of the chair, the left arm and hand being used in various ways to control the head of the patient. The mouth is opened as far as necessary, and the left hand is then used to hold the lips away and keep the jaw as steady as possible. (See Figs. 450, 451.) Selection and Use of Instruments. — The selection of instruments depends on the nature of the operation to be performed. The means used in extraction should be of the most simple character. Many de- ciduous teeth and permanent teeth from about which most of the pro- cess has been resorbed can often be easily extracted with the thumb and finger. Children feel less apprehension with this method than wlien an instrument is used. The thumb should be covered with a nai)kin and placed on the inner surface of the tooth with the fingers against the outside of the jaw. The tooth is then forced outwardly toward the cheek or lips. The roots of the deciduous teeth often break, but this is of little importance, for when extraction is demanded the roots are weakened by the natural process of resorption and will soon disappear. Elevators of the various patterns shown in Figs. 408, 44.3, 444, and 445 Fig. 443. Manner of holding elevator Fig. 407. should be used whenever practical)le for removing roots, and in some cases teeth also. Fig. 407 is especially useful in removing the third molars. GENERAL PRINCIPLES. 479 When the internal anatomy of the jaws is well understood, this will be appreciated. Fig. 444. Elevator in use labiallv. Fig. 426 shows how firmly the roots are embraced at their necks between the two hard plates of compact tissue. It is usually impossible Fro. 445. Elevator in use linressure being exerted upon the tooth), pressing against the handle nearest the palm just back of the joint. The first finger should rest a little between the handles, thus giving a firmer grip on the right handle (see Fig. 446). Many ope- GENERAL PRINCIPLES. 481 rators do not place the first finger between the handles (see Fig. 447j. The second and third fingers pass to the outside of the left handle and Fig. 446. Use of forceps. are used to close the forceps, while the little finger resting between the handles is used to open the forceps, the thumb being used to force Fig. 447. Use of forceps. the beaks into the required position. After the forceps is in position for extracting, then the first finger is placed along the side of the sec- 31 482 EXTRACTION OF TEETH. Olid finger to give more power to extract. After it has been decided to extract by nsing the forceps, the partieuhir forms indicated must be selected and arranged in a convenient place, ready for immediate use as needed. Especially should this be the case when the operation is done under the anesthetic influence of nitrous oxid. Having the patient's head in position, the forceps are grasped as previously described and the beaks adjusted to the tooth. As a rule, the inner beak should be placed in position first, and then the outer one — this is very important, especially for the lower teeth — taking care not to include a portion of the tongue or the soft tissues of the floor of the mouth, as both are liable to get in the way. When the forceps are adjusted to the inner and outer surfaces of the tooth, they should be forced between it and the gum until they come in contact with the edge of the alveolar process. It is a common error of students to use too much force in pressing the handles together; only sufficient force should be used to securely hold the tooth or root. The forceps should grasp as much of the roots as possible, avoiding pressure upon the crown and being careful not to force the beaks between the alveolar plates, as this would result in breaking one or both plates over the tooth or root extracted and also over the adjoining tooth. Cases have occurred in which the entire external plate of one side has been forced off in this w^ay. At times it maybe advisable to take away a portion of the outer plate, in which case the lancet shown in Fig. 409 should be used to cut through the gum a little beyond the point of process to be removed, dissecting up the gum slightly ; the inner beak is then adjusted and the outer one passed between the divided gum and the process as far as recpiired ; the forceps should then be closed with only sufficient force to cut through the bone and grasp the tooth, taking care not to crush it. After the forceps are in position the tooth is loosened by rotating it slightly if it be a round conical-rooted tooth, such as a central incisor, but if it be a flattened one it should be removed by an outward and inward movement. By the " out-and-in motion " is meant that after the forceps are ap- plied the force used in loosening teeth is directed in such a manner that the tooth is worked outward and inward from the median line of the mouth (see Fig. 426, in which the lines show the direction of the motion for each tooth). Tlie individual teeth do not always bear the same relation to the median line of the jaw as shown in Fig. 426. When the axis of a tooth is not regular it should be loosened by mov- ing backward and forward, and the movement should be in line with its strongest diameter. GENERAL PRINCIPLES— DECIDUOUS TEETH. 483 In the upper jaw the inward movement is made after the outer, but with not so much force, as the structure is more dense. Rotation of a tooth in extracting is seldom practiced, as the single- rooted teeth are usually flattened and teeth that have more than one root cannot be rotated. Of the single-rooted teeth, the upper central incisors alone have roots nearly conical in shape which permit rota- tion as well as the out-and-in motion. A rotary motion is usually of advantage in extracting the roots of the upper first bicuspid when double, and of the upper molars after the crowns are broken away so that the roots are disunited. These roots are usually round, conical, and somewhat curved in shape. If possible, the tooth should be kept in view during the operation so that the results of the movements may be seen. A beginner may let the forceps slip and extract the wrong tooth when he is not observ- ing each movement, but an experienced operator can almost depend on his sense of touch alone. The amount of pressure a tooth will stand while loosening it by an " out-and-in motion " depends on the size, con- dition, and density of the bony tissue surrounding it. Experience is the only reliable guide in this matter. When a tooth resists ordinary effort, if the operator is not quite sure of the cause of the resistance of the tooth, it is better to desist temporarily and allow the patient to rest in order to investigate the condition of the tooth and its surround- ings. Fig. 437 will give some idea of the causes of the resistance offered by apparently normal crowns. After the forceps are applied and the tooth slightly moved, if the operator has a cultivated sense of touch he will feel that the tooth is yielding in one particular direction ; as a general rule, the tooth should be carried in that way. The force applied to safely and judiciously extract teeth should be made with arm and wrist motion ; if the whole body is used the sense of touch is blunted and accidents are liable to occur. Extracting- Deciduous Teeth. — In extracting the deciduous teeth the principles involved are nearly the same as for the permanent. A care, however, must be taken that is not necessary with the perma- nent teeth, i. e. to avoid injuring the developing permanent teeth that are situated immediately beneath them. Fig. 448, which shows all the deciduous and the developing perma- nent teeth except the third molars, gives a true idea of their relative positions. Special attention is drawn to the position of the crowns of the bicuspids as related to the deciduous molars. It will be seen that they are situated between the roots of the latter teeth, and by using undue force in adjusting the forceps these crowns could easily be mis- placed, extracted, or injured. 484 EXTRACTION OF TEETH. If the deciduous teeth are extracted at the proper time they can usually be removed by the thumb and finger as described. If not, one of the forceps shown in Figs. 395 and f396 should be used. Fig. 448. Dentures of a child six years of age. Extraction of Individual Permanent Teeth. The anatomy of the individual teeth and the majority of their often- repeated variations as well as the general principles governing the extra(;ting operation, being understood, the extraction of each tooth will now be studied, those of the upper jaw being first considered. The Upper Teeth. THE central incisor. This tooth has a strong, round conical root. The forceps are carried into position by placing the inner beak at the palatal surface of the neck of the tooth ; the outer one is then placed in position and the instru- ment forced upward with a slight rotary motion between the gum and the tooth until it comes in contact with the alveolar process. As the THE UPPER TEETH. 485 root is round and conical, it is loosened by rotation and the out-and- in motion and then removed by drawing it directly from its socket. It is, as a rule, easily extracted. THE LATERAL INCISOR. This tooth is much smaller than the central. The root is flattened and somewhat curved, the apex being often bent in the direction of the cuspid teeth. After applying the forceps as directed for the central incisor, the motion should be outward and inward. As the tooth has a delicate root, the force used must be light. When loosening and removing it, care must be exercised, as its root is not straight. The tooth is carried in the direction of the least resistance, which is usually toward the cuspid tooth. THE CUSPID. This tooth is usually more firmly set in the jaw than any other, and it often requires considerable force to break up its attachments. The root is long and slightly flattened. After applying the forceps its attachments are broken up by the out-and-in motion. After loosening it is usually easily removed from its socket. As this tooth is erupted after the adjoining teeth are in position, it is often malposed. If the deciduous cuspid has been lost before its proper time, and the first bicuspid has pushed forward, there is no ' room for the cuspid to take its true position. This irregularity varies to a great extent. The cuspid may also be out of position from unknown causes. A marked specimen is seen in Fig. 442, where both cuspids are impacted. They were entirely covered by a bony lamina. Sometimes the roots of these teeth project into the maxillary sinus, or even into the nasal chamber, while the crowns aire impacted be- tween the palatal plate and the plate forming the floor of the nose. Fig. 449 represents a Fig. 449. cuspid, lateral, and central incisor which were extracted from the sinus, the roots being |:^ ^-\ \..\ imbedded in its inner wall. Teeth thus im- pacted are often a source of trouble in vari- '■ . \ V ous ways and when discovered should be re- ^^_ _g ^^^ moved. When the tooth is so covered by bone cuspid, lateral, and central .-, , ,-, /. ,1 tiji 1 incisor extracted from that the lorceps cannot be applied the bone maxillary sinus. must be cut away sufficiently to allow the forceps to grasp it. A very good instrument for removing the bone is the elevator shown in Fig. 407 ; after the point has been sharpened it may be used as a chisel or gouge. 486 EXTRACTION OF TEETH. THE BICUSPIDS. The first bicuspid usually has a bifurcated root and the only motion that can be used safely for loosening is the out-and-in, as these roots are sometimes considerably divergent. The removal after loosening is not Fig. 450. Showing position for extracting upper teetli of left side. always easily accomplished, a little outward pressure being frequently necessary. If the force required is used too suddenly the inner root is liable to break. The second bicuspid usually has a single flattened root, though occa- sionally it is bifurcated. The motion used to loosen this tooth is the outward and inward, using the same precaution as with the first bicus- pid on account of the possibility of a double root. THE UPPER TEETH. 487 THE FIRST AND SECOND MOLAES. These teeth are nearly similar, having three roots, two buccal and one palatal, which vary so much in degrees of separation that no set rule can be given for their extraction. The roots of the first are usually more divergent than those of the second. Only the out-and-in motion Fig. 451. Showing position for extracting upper teeth of right side can be used, rotation being out of the question in loosening them, as the roots often diverge to a great extent. (See j9. Fig. 441.) After the tooth has been loosened there is at times a difficulty in removing it, on account of the distance around the three roots ; owing to their divergence this distance is greater than the size of the anatomical neck of the tooth corresponding to the opening of the socket. The only general rule that can be given is to carry it in the direction of the least resistance. Each tooth has more or less of an individual character, and therefore the operator must be governed by circum- stances. The main precaution to be observed is not to be in too great haste, as there is danger of breaking one of the roots or re- moving a large piece of the outer plate of the alveolar process. (See Accidents, p. 494.) THE THIRD MOLAR. This tooth so varies as to the shape and number of its roots that it is seldom spoken of as an abnormal tooth, no matter in what form or 488 EXTRACTION OF TEETH. position it may be found ; the greater number have roots curved back- ward and outward. Their position in the jaw also varies considerably. The forceps shown in Fig. 395 is the instrument to use in extracting. After the forceps have been firmly placed, the principal motion is the out-and-in, though more out than in. If there is much resistance the hand should be carried outward and upward, or in the direction of the least resistance. This tooth is sometimes erupted at the side of the alveolar process with its occlusal surface pointing toward the cheek. It is not well to have the mouth opened too far, as it brings the coro- noid process of the lower jaw in the way. In stating the general rules of extracting, caution was given not to make the movements faster than could be seen ; this applies very partic- ularly to the third molar. It is so near the ascending ramus in the lower jaw that it is possible, especially when the roots are curved and spread out, to fracture this angle, or in the upper jaw the tuberosity may be broken away, thus opening into the maxillary sinus. The gum tis- sue often adheres to the posterior portion of this tooth ; when this hap- pens it is best to desist from attempts at extraction and sever the tissue from it with a curved lancet or scissors before removing the tooth with the forceps, or, as before advised, dissect the gum away before applying the forceps. The Lower Teeth. As a rule, the teeth of the lower jaw are more difficult to extract than are those of the upper jaw, the lips and cheeks being in the way. The tongue is also troublesome, covering the tooth, and when the inner beak of the forceps is placed in position especial care must be used to prevent part of the tongue from being caught in the instrument. THE ORAL OR ANTERIOR TEETH. (For position see Fig. 452.) These six teeth have small single, straight, compressed roots. Their extraction is only necessary when they become loosened by accident or from disease or when it is necessary to clear the mouth for inserting artificial teeth. The operator should stand a little back and to the right side of the chair, being somewhat elevated above the usual posi- tion, passing the first finger of the left hand between the lips and the alveolar border, and place the remaining fingers beneath the chin with the thumb on the inside of the teeth. For the incisors use the lower root forceps shown in Fig. 406 or the universal forceps shown in Fig. 396. The cuspids are larger and more firmly set ; delicate root forceps, therefore, are not usually suitable ; the instrument shown in Fig. 396 or, better, the bicuspid forceps Fig. 403 are much better. An out-and-in motion is proper for loosening all these teeth. THE LOWER TEETH. 489 THE . BICUSPIDS. The lower bicuspids have compressed roots seldom bifurcated, and are generally extracted by the out-and-in motion. The special forceps for these teeth should be made so that they grasp a considerable por- tion of the surface of the tooth. These teeth are often difficult to extract without breaking when all the teeth are in position, the roots Fig. 452. Showing position for extracting lower anterior teetli. being long and narrow and often situated in an awkward position. As shown in Fig. 425, the position of the roots of the second bicuspid is a little to the inner side of the anterior root of the first molar. The tooth illustrated in this particular case would be very difficult to ex- tract without breaking. 490 EXTRACTION OF TEETH. THE FIRST MOLAR. (For position see Fig. 453 for the left side, Fig. 454 for the right side.) The first molar, if in a month where all the teeth are in })osition, is generally the most difficnlt of all the teeth to extract. The roots are Fig. 453. Showing position for extracting lower teeth of the left side. nsually long and diverging. It is lower in the arch than the other teeth, and is in fact similar to an inverted keystone ; consequently, when extracted it is drawn through the arch. When the teeth are close together the second bicuspid and second molar yield a little, but great care must be taken that one or both of these teeth are not extracted with the first molar. In placing the forceps on the lower molars the points of tlie beaks of the special molar forceps (Fig. 392 or 404) are placed in between the roots on each side of the tooth. Care should be exercised to avoid including a portion of the tongue or soft tissues of the floor of the mouth in the forceps. If the forceps are not well placed the wrong tooth may be extracted, as it is possible for them to slip in between two teeth. In loosening these teeth the out-and-in motion is used, and as they are wedged in it is often necessary to continue this motion while extracting them from their sockets. At times it is advisable to move the tooth out- THE LOWER TEETH. 491 wardly after it has been slightly lifted from its socket. Occasionally the roots diverge so far that either the crown has to be broken from the Fig. 454. Showing position for extracting lower teeth of the right side. roots at their bifurcation or the tooth divided in the line of bifurcation with splitting forceps ; each root being then extracted separately. THE SECOND MOLAE. The roots of this tooth are not as diverging as those of the first molar, as may be seen by examining Fig. 421, nor is the tooth wedged in as tightly as in the case of the first molar. The out-and-in motion is required for these teeth, using the same precautions that are necessary in the extraction of the first molar. THE THIRD MOLAE. In these teeth the roots may vary so much in number and shape that there can hardly be said to be a typical third molar. Fig. 421 shows what might be called a normal third molar, but these are only found in well-developed jaws, where the teeth are not so large as to cause crowding. They vary in character from the one shown in Fig. 421 to the two shown in the right and left jaws represented in Figs. 437 and 438. Figs. 433, 434, 435 and 436 show other forms and posi- 492 EXTRACTION OF TEETH. tions of the third molar. There are also third molars having three, four, or five roots, o, Fig. 441, shows another form of the third molar ; h, c, d, e, f show where the third molar has united with the second molar ; g and h illustrate three molars united ; j, h, I, m, n, o, and p show variations of roots. The positions these teeth occupy may vary in all degrees from that shown in Fig. 421 to those shown in Figs. 432-438. Where the third molar is in the position shown in Fig. 421 and there are no other complications, its extraction is easy. The tooth is removed by placing either the special lower molar forceps shown in Fig. 405 or the forceps shown in Fig. 396 in position, and using the out-and-in motion with a slight raising of handles. But when it is of irregular form and position, as shown in the various illustrations, the difficulty increases with the degree of variance from that of the normal tooth shown in Fig. 421. These cases should be closely studied. If por- tions of the teeth are in view, as shown in Figs. 437 and 438, they will assist to some extent in the diagnosis of the position of the roots. In this particular case, the bone as well as the roots being much hyper- trojjhied, it would be impossible to extract the roots without fracturing the process to a greater or less extent. It will be noticed, on exam- ining the section Fig. 437, that to have fractured the inner portion of the jaw the inferior dental nerve and vessels and also the mylo-hyoid nerve and ^•essels would be endangered. If in attempting to extract this tooth it should not yield to a pressure which if increased would break the bone, it is better to desist and cut away the bone with a bur in the surgical engine as was done in the case of the specimen from which the illustration was made. Those represented in Figs. 433, 434, 435, and 436 would be more difficult to diagnosticate, as no portion of the teeth is in view. If trouble existed in this region the explora- tions would have to be made with sharp steel probes. The bone would then have to be cut away until the tooth could be grasped by the forceps. In Fig. 432 the third molar is in such position as to be easily ex- tracted, though if proper care were not used the extraction might have serious conscfpiences. It will be noticed that the points of the roots are just through the inner U-shaped cortical portion of the lower jaw below the mylo-hyoid ridge and project into the submaxillary region. Now, should this tooth or the roots be pushed downward in attempted ex- tracting, as is sometimes taught, it might be forced into the submaxillary region and consequently be lost for a time, with the possibility of having to perform a subsequent surgical operation to cut it out from the neck. An impacted third molar often causes great distress by initiating an inflammation which extends to the region surrounding the angle of the TREATMENT AFTER EXTRACTION. 493 jaw, and often including the temporo-maxillary articulation and soft parts within the mouth. Under these conditions the jaws can only be partly opened, deglutition is impaired, and solid food cannot he taken. One of two things must be done : either the offending tooth or the one in front of it must be extracted. If any part of the third molar can be seen it is best to extract that tooth ; the inflammation of the adjacent parts will generally quickly subside. As the mouth can only be opened slightly, it is impossible to use the large special molar forceps. An elevator is sometimes recommended in these cases, but it may prove to be a dangerous instrument to use under such conditions, for w^hen the tooth is lifted out of its position in the mouth, it might easily slip back into the larynx. It is well in some cases to loosen a tooth wdth an elevator and then remove it with the forceps shown in Fig. 396, Fig. 455. Showing the direction in which the lower third molar is to be extracted. as they are small and are so shaped that the beaks can be carried back to the tooth mainly along the vestibule of the mouth, the inner blade being placed between the teeth by passing the forceps l^ack of the second molar. Often it is impossible to see completely what is being done, therefore it is not well for a beginner to undertake this kind of extract- ing. After the forceps is in position the tooth should be worked in any direction in which it will yield ; this is generally outward, upward, and backward, in the manner of unfastening a hook. (See Fig. 455.) Treatment after Extraction. The operator should recognize immediately any accident that may have happened during the operation of extraction, and treat it as the circumstances indicate ; but if nothing unusual occurs, then the patient may be allowed a few moments' rest, after which the mouth should be 494 EXTRACTION OF TEETH. carefully examined. If there are any loose portions of the process or pieces of gum hanging to the parts operated upon, they should be re- moved by any convenient means, such as a curved pair of scissors or a curved lancet (Figs. 409 and 411). When several teeth have been extracted leaving ragged edges of the outer walls of the alveolar process, these should be removed with the excising forceps, or better still, by the use of either forceps Fig. 395 or 396, according to circumstances, as the beaks can be carried between the gum and the process better than can the blades of the excising forceps. An antiseptic mouth-wash consisting of a tablespoonful of phenol sodique to a glass of water should be used several times daily for the next few davs. Any other suitable antiseptic mouth-wash which may be more agreeable to the patient may be used instead, tliough the phenol sodique is highly efficacious. Occasionally, in a few days after extraction, pain will be noticed in and about the alveolus, especially when the tooth has been the seat of pericemental inflammation. Relief in such a case is usually given by removing any clot that may have formed, and breaking down the de- generated tissues which should have adhered to the root. A pledget of cotton saturated with the full-strength solution of phenol sodique should then be inserted as a dressing. Accidents. . When accidents of any kind whatever occur, the operator should be calm and appear perfect master of the situation. He should be pre- pared to successfully deal with whatever conditions may arise. One of the most common accidents is the breaking of a whole or portion of a tooth or root. If the operator has any doubt of his ability to remove the tooth entire, he should inform the patient that there is a possibility of its breaking, in which case not to be alarmed. If the tooth is removed without breakage so much the better ; even if it does break it will not cause alarm to the patient. It is more desirable that all of a tooth should be removed, for if its surrounding membrane has been inflamed, or if a root has been broken having a portion of the pulp attached, either will be the source of obstinate pain. It is better, however, under some circumstances, to let certain roots remain if they are broken, than to break away a large amount of process. Roots are sometimes so situated that they can be easily forced into the maxillary sinus (see Figs. 423 and 424), or into the submaxillary region (see Fig. 432), or upon the inferior dental nerve. If there are good reasons for believing that the njot will not cause undue pain, and there is danger of breaking a large amount of process, it is preferable to let it remain, as in a short time the contraction of the soft parts and ACCIDENTS. 495 the expulsive efforts of Nature will force the root outward and it can then be removed without danger. If roots are forced into the maxil- lary sinus they must be followed and removed. If several teeth are to be extracted, and the gum should adhere un- duly to one of them, the operator should desist from its removal and proceed with the other extractions, after which the adherent gum should be severed with a curved lancet or a pair of curved scissors and the tooth then removed. If the gum be much torn and the bone exposed to a great extent, it should be held in place by a few interrupted sutures. If, however, proper care is taken in extracting, this should not occur. In extracting crowded teeth, or those having frail alveolar surround- ings, it is possible to remove a piece of the alveolar plate, especially in Fig. 456. Fig. 457. Fig. 458. Fig. 460. Fig. 461. Fig. 462, Fig. 463. Fig. 464. extracting the first and second molars, the broken piece extending back- ward, forward, or in both directions to the adjoining tooth. (See Figs. 456 to 464.) The tooth in front may even be partially lifted from its socket. As soon as the operator sees the impending accident he should either stop and see if his method of extraction could be im- 496 EXTRACTIOy OF TEETH. proved, or, this point being negatively decided, hold the parts in posi- tion with the left hand as well as he can, and after the tooth is removed force the injured parts into position; they will usually stay, but if not, appliances of appropriate forms can be used for retention. In extracting the upper third molar, the tuberosity is sometimes broken awav, opening into the maxillary sinus (see Figs. 456, 457, 458, 461, and 464, showing where teeth have been carried away with the tuberositv). If it is a simple fracture the parts can be forced into place and thev will in a short time reunite. But if the parts are torn loose it will be of little use to try to replace them ; the best course is to trim away tlie ragged edges, using the curved scissors for this purpose. After such a fracture it is possible that hemorrhage may occur from rupture of the posterior dental artery. This is sometimes difficult to control. One of the best remedies, however, is to tightly pack the parts M'itli medicated gauze. This application must l)e left in for a few days and then be carefully removed. It is sometimes well to take out only part of the gauze at a time, the loosened portions being cut oif with a pair of curved scissors. Hemorrhage after extraction usually ceases in a short time, and then there is no occasion for treatment ; when, how- ever, the adjoining parts are much inflamed, or the patient is in an anemic condition, or the case is one of hemorrhagic diathesis, special treatment will be necessary. Hemorrhage of extraction may be divided into two classes, arterial and capillary. AVhen arterial, it is usually located in the socket of the tooth, and may usually be stopped without much difficulty by taking a twist of absorbent cotton, shaping it into a thin tapering roll, and thoroughly packing the socket. Before inserting the cotton tampon, it should be rolled in tannic acid until the fibers will hold no more, then the cotton is to be packed tightly into the alveolus with a dental plugger. In packing the cotton it is well to begin at one end and crimj) it upon itself until the socket is entirely filled. A narrow strip of iodoform gauze when ])acked in the same way makes a good plug, and the more rapid healing of tlie parts afterward and freedom from any offensive odor makes it a more satisfactory tam])on than the tannic acid and cotton plug. The plug in a few cases may require retention in position by compression. This is accomplished by holding a few folds of muslin or similar material over the plug, closing the mouth and l)inding the jaws together with a few turns of a Barton's bandage. (See Figs. 465 and 466.) Where hemorrhage occurs from the surrounding tissue, as in patients in an anemic condition or in cases of hemorrhagic diathesis, the case usually falls into the hands of a general practitioner for systemic treatment, but the local treatment usually employed by physicians in ACCIDEyTS. 497 these cases is often nnsatisfactory, many using Monsel's solution of persulfate of iron, which, although it may be a good stv'ptic for use in Fig. 465. Fig. 466. Barton's head bandasre. Fig. 46/ other parts of the body, should not be used in the mouth. The local treatment in such cases, whether soon after extracting or not, is first to remove all clots from the wound and find the exact place or places from which the blood is exuding. A suitable styptic and compression are the principal means used for stopping it, the latter perhaps being the most important. Tannic acid applied on cotton, lint, or similar substances, is a good styptic to use in the mouth. Iodoform gauze, for the reasons al- ready given, is better, and though it has not been used in this connection very much as yet, may eventually take the place of tannic acid and cotton. Compression can be applied as the ingenuity of the operator may direct. When a hemorrhage occurs from a socket between good teeth, it can be readily controlled by two ligatures, making one fast to each tooth ; then placing in position and tying the four ends together over the compress, as shown in Fig, 467. In a few rare cases an impression of the parts should be taken in wax or other modelling compound in order that a rubber or metallic plate can be made to hold the styptic compress in position. A ping of half- hardened plaster of Paris may be made and forced into the bleeding socket in obstinate cases, or in extremis the extracted tooth might be soaked well in phenol sodique and reinserted. The systemic treatment is often important ; if tlie patient is seen to be anemic or known to be of the hemorrhagic diathesis, the treat- ■A2 Showing compress and ligatures. 498 EXTRACTION OF TEETH. ment should be begun before extracting. This is done by thoroughly building up the system by a course of hygienic and tonic treatment. The cause of bleeding in cases where the hemorrhagic diathesis exists is but imperfectly understood ; the blood may be so defibrinated that it has lost the power of coagulation and so will not form a clot, or the muscular coats of the vessels have lost their tonicity, either through general debility or the lack of energy in the vasomotor nervous system, which prevents their contracting so as to close the lumen. Certainly the walls of the capillaries permit free transudation of the blood. In good health the proper coagulation and the contraction of the blood- vessels will stop the hemorrhage even when an artery of consider- able size is lacerated, especially if the flow be held in abeyance by arti- ficial means for a short time. It is when the blood will not coagulate and the vessels fail to contract that a thorough systemic treatment must be given. This lack of normal function on the part of the blood and vessels may arise from various diseases, and in order to judiciously treat a patient exhibiting the hemorrhagic diathesis a thorough exam- ination must be made and such treatment given as the diagnosis indi- cates. Among the most common causes of hemorrhage are anemia, syphilis, purpura, tuberculosis, and a generally impaired vitality, rarely an over-acting heart ; the passive hyperemia attendant upon a weak heart is a potent factor requiring a course of preliminary treatment. Specific and special diseases must of course receive the treatment peculiar to these conditions. On general principles the following tonics are advisable : Quassia, cinchona and its alkaloids, iron in its various forms, sulfuric and hydrochloric acids, arsenic, phosphorus, nux vomica and its alkaloid strychnin. W\x\\ these general tonics various hemo- statics can be given, such as alum, tannic acid, ergot, erigeron Cana- densis, and gallic acid. Very frequently the digestive organs require special medication, when such remedies as pepsin, pancreatin, hydro- chloric acid, and bismuth subnitrate are indicated. The following prescriptions have jjroved to be very excellent in their special province. As general tonics : gr.J ^. Strychnite sulphatis, Acidi arsenosi, Quinise sulphatis, gr. xxx Ferri sulj)hatis exsiccat., gr. xv. M. et ft. piluke Xo. xxx. S. One immediately after each meal. I|«. Elixir ferri, quinise et strychniae, fsiv. S. Teaspoonful four times daily. USE OF GENERAL ANESTHETICS. 499 To improve digestion and assimilation : I^. Acidi hydrochlorici diluti, f^ij ; Ext. ignatise amaris fld., f^j ; Pepsin, Siss ; Ext. ipecacuanhge fid., TTLiv ; Infusi gentianse comp., q.s. ut ft. f^vj. — M. S. Dessertspoonful in sherry glass of water immediately after meals. In cases of undue hemorrhage after extracting, it is well to adminis- ter a hemostatic while at the same time styptics and pressure are being applied locally. The following are very good : ^. Vin. ergotse (Squibb' s), f^iij. S. Teaspoonful every two hours. ^. Ext. ergotse solidificat., 3j ; Ext. cannabis indicse, gr. v ; Strychnise sulphatis, gr. ss. M. et ft. pilulse No. xxx. S. One pill three times a day. Gallic acid and aromatic sulfuric acid may be administered. Digitalin exhibited in doses of y^^ to ^ a grain three or four times daily for a series of weeks will often effect such change in the capillaries as to overcome the hemorrhagic tendency. This has been repeatedly and suc- cessfully accomplished in epistaxis, and as the conditions are analogous it can be employed in this diathesis with expectation of similar results. Extraction under the Influence of General Anesthetics. While it is undoubtedly true that the extraction of teeth under the influence of a general anesthetic is in accordance with the general spirit of the age which seeks to spare all suffering or cause the infliction of but slight pain, yet many evils attend their general and too often indiscriminate use. "A patient under the effect of so powerful a drug that consciousness is destroyed is nearer death than an ordinary human being, since the primary depressive influence upon the high nervous centres may speedily pass to the lower vital centres in the medulla oblongata." ^ The indiscriminate use of general anesthetics, beside their possible danger to life and health, has an accompanying evil in the demand for the extraction of teeth which are salvable and useful, but which ^ H. A. Hare, in Parli^ s Text-Book of Surgery, vol. ii. 500 EXTRACTION OF TEETH. a patient insists upon having removed in order to avoid the discom- fort attendant upon their treatment and filling. No one questions or denies the enormous benefit of general anesthetics in dentistry, particularly when painful operations are to be performed upon ner- vous women and children, but if the patient be willing to suffer a little pain it is generally better to extract without a general anesthetic, as in that case the patient can assist the operator by keeping the head in a desired position with the mouth and lips well open, and in various other wavs, while under the influence of an anesthetic the muscles supporting the head, jaws, and cheeks are so relaxed that it is dimcult to keep the mouth and lips well open. If the operation is to extract a difficult tooth, the operator is limited to the time when the patient is under the influence of an anesthetic, and in the case of nitrous oxid the time is very short ; but without an anes- thetic there is not this limitation as to time, and the extraction may be done with that care and deliberation essential to a proper operation. It is an important rule in any branch of surgery that the time required to do an operation must be sufficient to do it properly and without un- necessary injury to the adjoining tissues. Examination of a Patient before the Administration of a Gen- eral Anesthetic. — The physical examination should be made in such a way that it will not cause alarm to the patient. The result of this ex- amination governs the selection of the anesthetic, and to some extent shows how far the patient should be carried under its influence. It has been said that a greater amount of care should be used if the patient has or is suspected of having organic or functional disease of either the heart or the lungs. This is quite trne, but at the same time the greatest amount of care should be observed in all cases. For the physiological action of various anesthetics the student is referred to special works on this subject. The question often arises whether anesthetics should be used at all if the patient has either organic or functional disorder of the heart. That depends to a large degree on other conditions of the patient. If the shock of extraction will be less under ether or nitrous oxid, then by all means give the anesthetic and carry the patient fairly well under its influence, so that there will be neither pain nor knowledge of the ope- ration. Occasionally patients suffering from heart disorders can bear a certain amount of ])ain without shock ; in such cases it is better, if the operation be a simple one, to extract while in the normal condition. The use of ether for extracting has certain advantages. If for any reason the o])eration requires longer time for its performance than the influence of the nitrous oxid will last — say from thirty to sixty seconds — it is better to use ether. Ether can be given after the patient lias USE OF GENERAL ANESTHETICS. 501 Fig. 468. become anesthetized by nitrous oxid and oxygen and he may be kept un- der its influence for a considerable time ; in this way the struggling stage of ether is avoided. When the teeth are to be extracted at the patient's home or at any other place outside of the office, ether is more conve- niently carried than nitrous oxid. If properly used and the patient has perfect confidence in the operator, it can be so administered that one, two, or three teeth may be extracted during what is known as the first stage of ether anesthesia, before complete unconsciousness and long before the strug- gling stage commences. The best way to accomplish this is to administer the ether in a cone made by a napkin or towel, with the small end slightly opened so as to allow the patient to inhale a small quantity of air ; it also permits the patient to exhale freely and with a less suf- focating effect. It is well to place in the cone a small soft sponge that has been well washed with hot water. After the cone is ready the patient should be instructed to breathe several long and full inhalations ; this clears the lungs of much impure air and ac- customs the patient to the kind of breathing required. Then the appliance is placed in front of and some distance from the mouth and nose, being careful to allow none of the ether to drop from the cone upon the face, as it will demoralize the pa- tient. The inhaler is to be advanced toward the face slowly and gradually, watch- ing the effect upon the pa- tient ; if there is a tendency to cough, the advance should be interrupted until this has passed. After the cone has closed tightly over the mouth and nose, it is a good plan to ask the patient to hold up the left hand as long as possible ; this will concentrate his thoughts upon the act and away from the operation. When the hand begins to fall, the request to raise the hand should be repeated ; it will soon fall, and in a few seconds Nitrous oxid gasometer. 502 EXTRACTION OF TEETH. afterward one, two, or three teeth may be removed, the number de- pending entirely upon their position and the diiheulty to be overcome in their extraction. As soon as the teeth are extracted the head of the patient should be raised from the head- rest and the body carried forward, and, having a hand cuspidor in front, the patient should be Fig. 469. Water line To gas cylinder Sectional view of gasometer. requested to eject the blood from the mouth ; this direction is usually complied with. The patient in most instances recovers in a fcAv moments and with no disagreeable after-effects, but if the ether is carried beyond the struggling stage to the point of complete sur- gical narcosis the nauseating after-effects are very disagreeable unless the patient has been thoroughly prepared for the occasion. Nitrous oxid is the anesthetic most commonly administered for the USE OF GENERAL ANESTHETICS. 503 extraction of teeth, and nnder ordinary circumstances is the best. Until lately every operator was his own maker of the gas — this was a great disadvantage— but now it can be procured in a liquefied form com- FiG. 470. Nitrous oxid inhaler. pressed in cylinders. There are many diiferent appliances used for the administering of this gas even when using it in a condensed form. The most prominent one is that shown in Figs. 468 and 469, in which 504 EXTRACTION OF TEETH. the ga^ i- drawn into a reservoir and then passes through a flexible tube into a receiving-bag, and thence passes to the mouth-piece (Fig. 470). Fig. 471. Hood inhaler. The two principal mouth-pieces are Fig. 470, which should liave the detachable lip-.shield removed so that the tube may be placed directly into tlie mouth and the lips comjn-essed around the tube by the operator, and Fig. 471, which is known as a hood inhaler; it is USE OF GENERAL ANESTHETICS. 505 made to cover the nose as well as the mouth. The advantage of the first mouth-piece is that the lips may be closely watched for the change of color denoting oxygen-starvation of the blood, which the experienced operator combats by admitting a certain amount of air with the gas as required. Fig. 472 represents a portable appliance to be used at a patient's home or away from the regular office. Fig. 472. Portable nitrous oxid apparatus. Dr. He-witt's Method. — Dr. Frederick Hewitt of London, England, has devised the apparatus shown in Figs. 473 and 474. The three cylinders contain the compressed gas, two being filled with nitrous oxid and one with oxygen. The valves of the cylinders are opened by a key which is controlled by the foot of the operator. The tube passing from the cylinders to the receiving-bag is double, a smaller tube being placed within the outer larger tube. The receiving-bag is also double, being divided by a rubber septum into two compartments which have their outlet in the double tube which leads to the inhaler. To the receiving- bag is attached a mixing-chamber, and to this the inhaling-tube or hood is fastened. This appliance is used very successfully in England and has been introduced into the United States. It has proved satisfactory to all who have tried it. The bags and tubing should be made of more durable material when intended for use in the American climate. 506 EXTRACTION OF TEETH. The manner in which the appliance is used is as follows : The valves in the mixing-chamber (Fig. 474) are closed, then oxygen is let into its compartment of the receiving-bag until the latter is nearly filled, when the nitrous oxid is admitted into its compartment. The patient being prepared, the inhaling-tube or hood is placed in position, and the patient is directed to breathe — long, full, and steadily. If the tube is used it is necessary to close the nose by the thumb and finger. Fig. 473. Complete apparatus of Dr. Hewitt for adnunistering mixed nitrous oxid and oxygen. The valves are not changed for a few inhalations, during which time only air is inhaled ; then, pressing the indicator a downward to the first notch b, the air is cut off, and the patient receives pure nitrous oxid ; this is allowed for a few more inhalations, and then the indicator is car- ried to the next notch and one part of oxygen is allowed to pass into the respiration. When the indicator is carried to the third notch two parts are received by the patient, and so on until the maximum amount of oxygen required by the patient has been reached. It has been found by careful study of many thousands of cases and by special scientific investigation that the asi)hyxial condition incident to most cases of nitrous oxid inhalation is quite unnecessary to the pro- USE OF GENERAL ANESTHETICS. 507 duction of nitrous oxid anesthesia. It is also justly considered to be subjecting a patient to an unwarrantable danger to permit the asphyxial effect to manifest itself to a profound degree, as in many cases it is a menace to life and health, and might have a fatal effect. The object of Dr. Hewitt's method is to control or eliminate the asphyxial element by administering a requisite amount of oxygen. Fig. 474. Showing arrangement of the mixing-chamber, with dial and valve for controlling the relative proportions of the gases. No fixed rule can be laid down for the quantity of oxygen to be added, as each case will require a different amount and this amount varies during the several stages of the anesthetic procedure. The operator is guided entirely by the symptoms of the patient during the administration, his object being to avoid on the one hand the tendency toward asphyxia indicated by cyanosis of the lips, and return of con- sciousness and sensation on the other hand, which is easily produced by an excess of oxygen. By the admixture of oxygen, as in Dr. Hewitt's method, the anesthesia is somewhat prolonged over the ordinary nitrous oxid method and is slower of induction, but there is entire absence of cyanosis, stertorous breathing, jactitation, or any of the symptoms of asphyxia. Similar results are obtained when air is admitted to the patient during the nitrous oxid administration. The details of this procedure are set forth in the following chapter. CHAPTER XIX. (Continued). EXTRACTION OF TEETH UNDER NITROUS OXID ANESTHESIA. By J. D. Thomas, D. D. S. To extract a tooth without the aid of an anesthetic is to-day little short of barbarous. It is cruel to the patient, and if the subject be a child, wantonly so. Very few people can submit to the operation with- out more or less physical resistance, and even though this be involuntary no operator can do full justice in such a case, no matter how skillful he may be. Such resistance causes more or less unnecessary strain to be applied in one direction or another against the process, which results in increased inflammation as a sequence. Besides, as a rule the liability of breaking the tooth or portions of the alveolar plate or other accidents is increased a hundredfold. Nitrous oxid is in all respects the very best anesthetic for the pur- poses of the dentist. Properly used, it is almost entirely free from danger and is rarely productive of nausea or depression as an after- effect, even temporarily. It seldom requires over sixty seconds to pro- duce anesthesia, and in less than that period of time the patient is fully recovered, with no knowledge of the operation, and is ready to depart as soon as bleeding ceases. To accomplish such a result, of course, requires experience and some degree of dexterity, but the con- ditions are such that any dentist with a fair amount of experience can o])erate successfully with it for the removal of from one to four or five teeth, and perhaps more — the main essential in operating by the aid of nitrous oxid being to utilize every second of time during the period of anesthesia, and not to waste it in hunting forceps or deciding how they should be used. The best success is obtained by formulating a system of working by which one can accomplish the most in the shortest space of time. The operating period seldom extends over forty-five seconds and often less, so that every second wasted in any way whatever is so much time lost, and success is diminished to just that extent. Nitrous oxid must be absolutely pure, and if be kept over water it must be fresh. In former times when the dentist manufactured his own 508 ADMINISTRATION OF NITROUS OXID. 509 gas, to ensure perfect purity it was necessary to test the ammonia nitrate before using it for making the nitrous oxid, but at the present day the pure gas is made with great accuracy by the manufacturers and is supplied chemically pure, compressed in cylinders, so that the individ- ual dentist is relieved of the responsibility of manufacturing his own gas and of the troubles necessary to secure purity. The first essential to success in its administration is a perfect INHALER. This should be sufficiently large to permit the patient to breathe without the slightest exertion. Patients are always in a more or less nervous state upon approaching the dental chair for extraction. There is usually accelerated heart-beat and consequently deranged respiration, and unless they can breathe through the inhaler with per- fect freedom they labor under a sense of suffiDcation which adds greatly to their apprehension and disturbs their equanimity while passing under the influence of the anesthetic. The inhaler shown in Fig. 471 is perhaps the best one upon the market, but has the disadvantage of having hard disk valves, and while the size is sufficiently large for most purposes the space between the outer circumference of the disk and the inner circle of the pipe is so small that it does not at all times permit of free ingress of the gas to the lungs, and, besides, such valves are not always airtight. The best inhaler is one made of vulcanized rubber turned to the proper dimension and fitted with valves made of rubber dam (Fig. 475). These valves have the property of fitting closely, making the Fia. 475. Thomas's inhaler. passages airtight, and being flexible they admit the gas to the lungs with little or no obstruction. This inhaler is the one employed by most operators who make a specialty of extraction, and is made only upon special order. 510 EXTRACTION OF TEETH UNDER NITROUS OXID. In giving nitrous oxid it is necessary that the valves of the inhaler shall be airtight, for if there is a leakage by which air is constantly being admitted, it will interfere greatly with the production of the desired results. The hood face-piece should never be used. Aside from the impossibility of fitting the face so closely as to preclude the admis- sion of some air during the administration, particularly when beard exists, it covers the lips from view and these are an important index dur- ing the process of anesthesia ; the color of the blood as shown through the mucous membrane of the lips should never be lost to sight. There is no separation of the elements of nitrous oxid at the tem- perature of the human body, or during its inhalation, consequently it is practically an inert gas so far as its power to support life is con- cerned. It possesses strong anesthetic properties but it is also to a degree productive of asphyxia, and the color of the lips must be ob- served as a guide to indicate the extent to which asphyxia is taking place. It has been previously said that the valves of the inhaler must be airtight, for a constant leakage of air will prevent the production of complete anesthesia, and yet at the proper time during the inhala- tion the admission of air, controlled by opening the nose or raising the lips, is not only desirable but essential to the proper and successful ex- hibition of the anesthetic. By the judicious admission of air at the proper time the accompany- ing symptoms of approaching asphyxia are obviated and perfect anes- tliesia is secured without any of the convulsive muscular twitching which takes place when the pure gas is given. Dr. Hewitt of London advocates the admixture of oxygen with nitrous oxid, for which he has introduced the appliances described on p. 505, but by admitting air as here suggested the results are obtained with less manipulation and the patient is not led to imagine that he is undergoing a serious ordeal, is more readily and peacefully brought under its influence, and has less occasion for nervous apprehension. The use of props to keep the jaws open is necessary to insure suc- cess. They give free scope for operating, and there is no time lost in prying the mouth open, as always happens when props are not used. . Props made of hard wood and of diiferent sizes are the most satisfactory ; they should have strings attached, more to reassure the patient than for any other reason. Unfortunately, a lumiber of years ago a patient died as a result of getting a cork in the larynx, and this has never been forgotten. Consequently the string is an assurance to the patient that the prop cannot slip down the throat. The ordinary dental chair is not desirable for use in administering nitrous oxid, particularly those chairs having stationary footstools at- tached. Patients are sometimes restless, and every motion made by the ADMINISTRATION OF NITROUS OXID. 511 feet upon a fixed footstool will produce a responsive movement of the body, thereby increasing the risk of accident to the part being operated upon. A detached stool upon casters is easily pushed away, so that any disposition to move the extremities may be permitted without affecting the stability of the upper part of the body. This apparent resistance on the part of the patient is not necessarily the indication of a knowledge of what is being done ; the upper brain function may be paralyzed while the sensory peripherals and motor ganglia are not, under which circumstances the patient is not thoroughly anesthetized. Resistance may take place at the beginning or just at the termination of the anesthetic procedure, and if the operator ceases at once the patient will declare absolute unconsciousness of the operation. It is, however, sometimes permissible to operate during the stage just noted in cases where the systemic conditions are such that it would be unwise to carry the patient to the state of profound insensibility. These are, however, exceptions and not the rule. To have the exhibition per- fectly satisfactory there should be no resistance or outcry. A competent assistant is necessary, not only as a protection against charges which might be suggested by lascivious dreams — as has occurred when ether has been employed (though the period of insensibility under nitrous oxid is so short that it would seem that no one, however evilly or honestly disposed, could ever sustain such a charge) — but an assist- ant can render much aid by holding the tube, lowering or raising the head, taking care that the operator does not bruise the lips, holding the patient if restless, particularly the hands, and waiting upon the patient during recovery from the anesthetic. The assistant should be a woman, as it adds very materially to the comfort of female patients to have such a person in attendance. The operator should receive the patient in such a manner as to inspire entire confidence. If necessary, any doubts or possibilities of accident should be clearly explained to the patient, so that in the event of untoward results there will not be a humiliating sense of failure. The patient is seated, and after a careful examination has been made and the condition of the tooth or teeth is ascertained, the prop is placed where it will be least in the way. The assistant then places the tube in the mouth and the patient is directed to close the lips and breathe through the mouth instead of the nose ; in the meantime closing the nostrils with the third finger and thumb of the left hand, the first and second pressing the upper lip about the mouthpiece, while the thumb and fingers of the right hand support the lower lip. While inhaling the gas it is desirable that patients should breathe as in ordinary respiration, for two reasons : First, if instructed to take long and deep breaths they exert themselves beyond their natural 512 EXTRACTION OF TEETH UNDER NITROUS OX ID. rhythm, and Avith unconsciousness comes involuntary suspension for some seconds, and should it occur in one who becomes quickly asphyxiated the few seconds of suspension are sufficient to produce alarming symp- toms which will require some effort to counteract. Second, if the patient breathe slower or less deeply than is natural there is a sense of suffocation produced which grows in intensity until unconscious- ness supervenes, when the lungs and diaphragm will exert their func- tion, producing violent respiratory effort which will be followed by marked exhaustion upon recovery. None of these effects need be produced if the operator have complete control of the situation. No one can explain the symptoms of approaching and complete anesthesia in such a manner as will inform a novice sufficiently well to undertake the responsibility of administering the gas ; these can only be learned through observation and experience, but the first prominent indication will be a discoloring of the lips and subsequent pallor of countenance, which is not, however, an indication of cardiac depres- sion, but is due to the blood color shown through the skin. Should the patient be of the blonde and florid type this appearance will be more marked, and it is here that the admission of a small amount of air is called for, particularly if the blueness seems to approach more rapidly than the anesthesia. If the pure gas is given to complete narcosis, there will be twitching of the muscles of the neck and wrists. Stertor and irregular breathing and sometimes decided convulsive action occur, which to one inexperi- enced becomes distressing, if not alarming, to behold. All these symptoms are at once relieved by air-breathing, and if there is a judicious admission of air during the administration of the anesthetic they will be avoided entirely. The patient being anesthetized — and the instruments being always in place so that there will be no delay in picking up the pair of forceps required, so that every second of time may be utilized by the work in hand — the next step is the extraction. The Operation of Extraction. — The proper way to perform the operation is to stand in one position, at the right side of the patient, during the whole proceeding. For extracting with the greatest facility the operator should assume such a position that in standing erect the patient's head will be about opposite his upper waistcoat pocket. To do this a pair of stools should be used, one just back of the chair and one by the side which may be easily pushed aside when not needed. While administering, the operator can stand upon the floor, and ascend the stool just before the time for operating. This position is assumed by the most successful operating s^iecialists, and is adopted as the result of long experience and dictated by the desire to bring about a position THE OPERATION OF EXTRACTION. 513 for work which permits of its most rapid performance and at the same time enables him to bring to bear the greatest amount of force with the least physical exertion. In the position described, main force for pull- ing is supplied by the use of the legs and body, the hands and arms being used for skillful guidance. When extracting, for example, a lower tooth, and it is necessary to force the beaks of the forceps well clown through the process, the instrument is manipulated by the hand and wrist with the arm held closely to the body to steady it. The weight of the body is allowed to descend to the proper degree by bending the knees, and when the for- ceps are fixed, should force for pulling be required, the straightening of the knees will raise the body, the arm being held firmly as described. The hand will be used exclusively for manipulating and guiding, while the force will be supplied by straightening the knees much the same as is applied in lifting weight from the ground. Of course, to become expert one must have all of his limbs equally trained. In operating on the upper jaw the method is much the same, only reversed, bending the knees first to lower the body and forcing the instrument to position by straightening and throwing as much of the bodily weight upon the arm, by bending the knees, as is necessary for pulling. By so doing a tooth will never be allowed to leave the socket suddenly as by a jerk, for the operator has perfect control of his hand and wrist, and the danger of bruising the opposite teeth in either jaw by the forceps is avoided. The Forceps. — Seven pairs of forceps are all that are required for extraction in ordinary cases. For the upper teeth, a right and left pair for the molars, a bayonet-shaped instrument with the outer beak pointed to fit between the buccal roots, and both beaks serrated. In work- ing upon both sides of the mouth a pair without pointed beaks may be used with advantage to avoid changing. One alveolar pair will suffice for the roots of all molars and bicuspids on either side. These are made bayonet-shaped with smooth concave beaks, but having well sharpened edges. The pair for the incisors is straight, with beaks simi- lar to the alveolar pair, and when extracting, say all the upper teeth, can be used upon all ten front ones with equal facility. For teeth in the lower jaw the molar pair is made with both beaks pointed, serrated, and gracefully curved so as to bring the force as nearly direct as possible; these are equally applicable for all the molars on either side and are shaped the same as the alveolar pair. The alveolar pair are shaped the same as those for the molars, have smooth concave beaks with sharp edges, and are used for all molar roots and bicuspids (Fig. 476). The pair for front teeth is curved under the handle and may have serrated beaks, as the roots of the lower centrals and laterals 33 514 EXTRACTION OF TEETH UNDER NITROUS OXID. Fig. 47 i m W^ Kccyc JJ^S^ 1^^. Alveolar forceps. are so flat that a sharp beak is apt to cut them off, if too much grasp is applied. They seldom require the force necessary in the extraction of other teeth. Forceps should not be nickel-plated. This produces a slippery or "greasy" feeling to the handle, making the hold less secure, which increases the force of the operator's grasp, consequently the liability of catting or crushing the tooth. With forceps having beaks that are not serrated, teeth having conical tapering roots Avill prevent the perfect fitting of the cutting edge ; these will sometimes slip through the posterior opening of the upper or lower alveolar pairs with great force. The writer has seen, in one instance, a tooth slip through the beaks of an unserrated pair of for- ceps and break a pane of glass in front of the chair, and an under single molar root which shot up with sufficient velocity to penetrate the soft palate. In extracting, particularly under nitrous oxid, no instrument should be used which will not securely retain any tooth or root until it is safely placed outside the mouth. Elevators are Avholly out of place when work- ing under an anesthetic. They permit no control of the root or tooth whatever, and the liability of a tooth slipping into the throat under such circumstances is too great to warrant the risk. The art or " knack " of extract- ing does not consist of giving a rotary motion to one kind of tooth and a lateral or " in-and-out motion " to another, but rather of " working'" the tooth in the socket without any pulling until it is started or loosened from its at- tachment, when the pulling force may be applied, and to do this the forceps must be placed upon a tooth so nicely that the tooth and instrument will feel to the hand THE OPERATION OF EXTRACTION. 515 as one continuous object, so that the shghtest motion in any direction will have immediate effect in " starting " the tooth. The operation is completed by continued working while the pulling is applied in the direction which will prove the most effective in dislodgment. This " working " should be done with as little motion as is possible, for the smallest degree of straining upon the process laterally only adds so much more distention to the alveolar plates, and increases the inflammation and pain after the operation. When nitrous oxid was first introduced and extracting was transferred to those who made it a specialty, it was noticed that there was less soreness of the mouth follow- ing the operation, and it was thought by some that the oxygen of the gas produced a beneficial effect upon the blood which caused better healing, but such is not the case. The object, in extracting, of one who becomes expert by constant practice is to save the surrounding parts from all unnecessary strain, consequently less pain and soreness follows the operation. There are teeth having curved and divergent roots, and cases of exostosis, which will rec[uire great effort to remove, but even in these the position as- sumed and the process of "working" the tooth in the direction of the force applied all tend to accomplish the result with less injury than Avould be otherwise produced. In this way the breaking of a tooth need seldom occur unless inten- tionally. If in extracting an upper or lower molar one finds by the extra amount of force required that it will not readily yield, then it is better to break the crown off and with the sharp alveolar forceps remove the roots separately. This can be done with less injury to the alveolar plates than if much greater force were applied to remove the tooth as a whole. There will be cases of fracture of points of roots which are much curved or divergent, but many of these retained fragments may be per- mitted to remain until in the process of exfoliation they come to the surface if their retention is regarded as likely to give rise to less trouble than the injury incident to their removal would cause. But these need rarely occur if the operator has by experience acquired that sense of feeling which tells him at once the direction of the curve or the size of the exostosis. Inverted or impacted third molars are the most difficult cases which present themselves for extraction. Instead of being surrounded by pliable process they are planted in compact bone at the angle of the jaw, bound in by the second molar in front and hard bone on the buccal side, so that above it in the angle is the only direction offered for removal, working them toward the tongue where the bone is thinnest. 516 EXTRACTION OF TEETH UNDER NITROUS OX ID. In addition to the difficulty in removing these teeth, this severe process of pressing the inner alveolar plate toward the tongue excites a state of inflammation, easily communicated to the soft tissues of the throat, and the after-effects assume in many cases such serious condi- tions that it is better practice to remove the second molar. If the third molar is sound it may remain and will cause no further trouble, as the jirimary difficulty was caused by crowding and pressing upon the second molar ; and should it be necessary, from decay, to re- move it, the extraction of the second molar first, renders the oi)eration sim})le and easy of accomplishment. After-treatment. — When a tooth continues troublesome beyi^nd the possibilitv of saving, extraction is advised as a final resort and usually but little if any thought is given to the after-treatment. A dentist should not dismiss his patient after extraction without further atten- tion. The operation of tooth extraction often requires the application of much physical force. Being situated in connection with the soft tissues of the mouth and the different brandies of the fifth pair of cranial nerves, patients sometimes suffer just as severely for a time after the operation as before it. Teeth with exostosed, curved, or diver- gent roots cannot be removed without a considerable strain to the sur- rounding alveolar process ; if such cases have been in a condition of ])ericementitis or incipient abscess the operation is sure to be followed by considerable pain and increased inflammation. In ordinary cases appropriate mouth-washes will accelerate the heal- ing process, but in the cases cited it is better to first apply heat by hold- ing water, as hot as can be borne, over the wound. If the inflannnation tends to the production of pus, the heat will hasten the jirocess and relief will be more speedily obtained ; should it be otherwise the hot aii])lication l:)rings quick relief by distending the capillaries and pro- moting rapid diffusion. After extraction antiseptic mouth-washes should be used for several days. Should pus be discharged into the socket it is necessary to keep it clear of putrescence by antiseptic syringing and dressings, such as 3 per cent, pyrozone or a 20 per cent, solution of phenol sodique. In cases of severe abscess where extraction is indicated, necrosis of the process invariably accompanies to a greater or less extent, and such a condition will require careful subsequent treatment. Sometimes the ])ulps of the adjoining teeth will be destroyed if the inflammation has extended beyond the limits of the original abscessed tooth ; this must also be carefully watched. These conditions appear much more fre- quently than formerly, as a consequence of the system of ])r()longed treatment of pulpless teeth with chronic abscesses, wliich has been fol- lowed for some years. THE OPERATION OF EXTRACTION. 517 Frequently this necrotic condition involves the alveolar plates ex- tending over the surfaces of two or three adjoining teeth. After free discharge has been obtained by the hot application and the cleansing of the socket with hydrogen dioxid, an application of a ten-grain solu- tion of zinc sulfate will soon cause the sequestrum to form and exfolia- tion to take place. Hemorrhag-e. — This will seldom occur if the proper care is taken not to lacerate the gums or distend the process. It is well in cases which exhibit a tendency to excessive bleeding to apply phenol sodique or tannic acid before permitting patients to leave the office, at which time the application will generally prove sufficient for the purpose, but for cases of the hemorrhagic diathesis in which the bleeding is either primary or secondary, these remedies are not as happy in their results as Monsel's solution. Many object to this remedy on account of its unpleasantness in the mouth, but it is the quickest and most effective hemostatic, and may be used with little or no objection. It is well to first touch the surface of the gum down to the edge of the process with silver nitrate, which will check the capillary bleed- ing temporarily, and immediately apply a drop of Monsel's solution on a pledget of cotton upon the spot from whence the blood comes, packing it well into the socket and holding it firmly with the finger for a few minutes. In most cases this will be sufficient, but should it not be so the hemorrhage will have been reduced to very little oozing, when a second pledget may be placed in like manner to the first ; success has by this means always proved certain in a few minutes in the hands of the writer. The packing should be removed the next day and the cavity wiped with a 10 per cent, solution of silver nitrate ; a dressing of phenol sodique should then be lightly applied, after which liability to recur- rence of the bleeding ceases and the soreness soon disappears. CHAPTER XIX. (Concluded). LOCAL ANESTHETICS AND TOOTH EXTRACTION. By Henry H. Burchard, M. D., D. D. S. Prior to the discovery and application of cocain, the local anes- thetics employed to produce a condition of analgesia of the structures surrounding a tooth to be extracted were sprays of extremely volatile substances. Through the rapid evaporation of a spray of one of the lighter hydrocarbons, a condition of refrigeration of tissues was brought about during which a tooth could be extracted painlessly. Sprays of rhigolene and of ethylic ether have been superseded by those of ethyl and of methyl chlorid, these substances being more volatile ; directed in a fine spray over the gum of the tooth to be extracted, an intense local anemia is produced, and as a consequence analgesia results. If the refrigeration be rapidly produced and the operation be performed promptly upon the attaining of analgesia, the frozen tissues recover with but slight reaction. It is to be remembered that the tissues are frozen, and if the action be prolonged a condition akin to chilblain is present. The mode of application is as follows: All of the mucous membrane, except that over the roots of the doomed tooth, is to be pro- tected from the spray by means of napkins. The spray is directed against the exposed gum, the vial containing the ethyl chlorid being held about a foot from the mouth. When the gum becomes intensely anemic, indicated by pronounced whiteness, the tooth is to be extracted. Ethyl chlorid must be kept in a cool place, and far from any flame ; it is inflammable and explosive. Preparations containing cocain (benzoyl-methyl-ecgonin) have to a great extent superseded all other local anesthetics employed for this purpose. It was clearly shown soon after the introduction of this alkaloid that its local anesthetic action when a])plied to the gums did not extend beyond the depth of the mucous membrane, so that its epi- dermic ajiplication does not render the operation of tooth extraction painless. The hypodermatic application was found to render the tissues infiltrated perfectly analgesic. A recklessness was evinced in its use after this method which was promptly followed by repeated disasters ; 518 COCA IN. 519 a formidable list of casualties grew. Reports of cases of respiratory and of cardiac paralysis following its employment were not uncommon. It apparently needed disaster to demonstrate that cocain belonged in the category of actively poisonous alkaloids, being by no means the bland and safe agent many operators seemed to think it. This lesson, learned at great cost, is one the operator is ever to heed, particularly in the hypodermatic employment of the agent. Dr. M. H. Cryer has re- ported ^ cases of ascending degenerations of the trunks of the maxillary nerves following upon cocain injections about the jaws. For the origin, composition, physiological effects, and toxicology of the drug the student is referred to the standard works upon materia medica. There are several points, however, which cannot be over- emphasized, the first being in regard to the drug itself. A full dose of cocain hydrochlorid by the stomach is about gr. f . The composition of the commercial specimens is not constant ; some of them appear to contain the actively poisonous alkaloid isatropylcocain. A safe dose when applied hypodermatically is not in excess of gr. ^. The lethal effect of cocain is upon the respiratory centre. Its absorption is followed by a stimulation of the cardiac and respira- tory functions, which is commonly followed by a reaction, the stimu- lation giving way to depression. Idiosyncrasies as to the effects of cocain are common ; cases of susceptible women have been noted in which gr. ^ produced toxic effects. It is to be noted that the depres- sion, following as a secondary effect upon the primary stimulation, may not occur for an hour or later. In prescribing cocain for hypodermatic injection, the analgesic is the first element to be considered in the prescription. The dose is not to exceed gr. ^. The second factor demanding attention is a physio- logical antidote, one which will not neutralize the analgesic effect and yet will prevent the toxic action of the cocain upon the cardiac and respiratory functions. Morphin is that agent. As its full physiological effect is not required, a small dose, gr. -^, will be sufficient. The next ingredient of the prescription is an agent which shall prevent abrupt spastic contraction of the arteries and heart. Trinitrin is this agent. One drop of the 1 per cent, solution is the indicated dose. Fungi develop freely in solutions of cocain, so that if the pre- scription is to be a permanent solution, an antiseptic is required to prevent decomposition. Cinnamic alcohol answers well for this pur- pose. One drop of carbolic acid to each half-grain of cocain is an efficient antiseptic. By boiling cocain is split up into methyl, benzoic acid, and ecgonin, so that cocain solutions cannot be sterilized by boiling. ^ Proc. Academy of Stomatolofjy, Philadelphia, 1896. 520 LOCAL ANESTHETICS AXD TOOTH EXTRACTION. The dose commonly employed of the components of the prescription IS- ^. Cocainse hydrochlorid., gr-i; Morphinse siilph., gr- T2 I or Atropina? .siilph., g^- 150 ; Trinitrin. (1 per cent, sol.), gtt. j ; Acid, carbolic. gtt.j; A q life. q. s. 3SS.— M. S. The above represents a half-syringefiil and is a full dose. This solution has been employed with general success, provided strict antiseptic precautions have been taken. Untoward results are occasionally found even with this seemingly safe formula. In the hypodermatic use of cocain the relatively safe maximum dose should never be exceeded and the exact amount administered in a given case always definitely known. A common error has been the dependence upon solutions of a given percentage composition. The danger of such dependence becomes evident when it is considered that the safe maxi- mum dose of cocain salt may be easily exceeded by the use of a sufficient quantity of a low-percentage solution, while on the other hand it is quite possible to keep within the limits of safety by using minute quantities of a high-percentage solution. The supposed harmlessness of a dilute cocain solution is erroneous and misleading unless the factor of the absolute quantity of the drug contained in a given amount of solution is constantly kept in mind. A method which is in all respects safer and which enables the oper- ator at all times to know the exact amount of cocain salt injected is to make the solution upon the basis of eight grains of the salt to one ounce of the menstruum, which will give one grain in each drachm and -^^ of a grain in each minim. Of such a solution from five to eight minims may be injected about a tooth with a reasonable degree of assurance that the safe limits of physiological eifect have not been exceeded. The menstruum in which these ingredients are combined is an inter- esting feature. It has been repeatedly shown that the injection of a quantity of water will produce anesthesia of a region. The nerve fila- ments are compressed by the fluid and do not transmit painful impres- sions. Dr. Schleich of Greifswald ' follows, for the induction of local anes- thesia for operations in general surgery, an infiltration method. The injection is divided and the punctures made seriatim about the territory to be operated upon. The remarkable feature of his procedure is the minute dose employed. He uses a 1 : 4000 solution of cocain, to which » T. Parvin, Proc. Phila. Co. Med. Soc, Nov. 13, 1895. SCHLEICH'S SOLUTIOyS^TBOPACOCAIN. 521 is added A of 1 per cent, sodium clilorid and a small quantity of 4 per cent, tricresol. One syringeful, about a drachm, is sufficient to infil- trate the tissues about a tooth and render its extraction painless. A drachm of the 1 : 4000 solution contains about gr. y\j- of cocain. The strongest solution employed by Schleich is a 1 : 500, A drachm of such a solution would contain less than gr. ^ of cocain. Dr. W. F. Litch (ibid.) has pointed out that low-percentage solutions will give a safer result than those of high percentage, even though the absolute amount of the drug should be the same. It is seen, therefore, that the quan- tity of menstruum in which the dose of cocain is suspended is an im- portant consideration. Tablets for making Schleich's solutions may be had of pharmaceu- tists. Tablets for making the strong solution contain — ^,. Cocainee hydrochl., gi'-lj Morphinse hydrochl., gr Sodii chlorid., gr. S. Dissolve in Vfi 100 of distilled water. 1 . 40 > Almost without exception the nostrums advertised and sold under high-sounding titles, for employment in this field, contain cocain. Neither their names nor any information vouchsafed by their venders give any indication of the amount of alkaloid present, and so all of them should be tabooed. It is nothing short of criminal to employ these nostrums without a knowledge of their exact composition. Tropacocain (benzoyl pseudo-tropin) has been employed to render the operation of tooth extraction painless. It possesses decided advan- tages over cocain. It is only one-half as toxic ; has but slightly de- pressant action upon the cardiac ganglia ; has no paralyzant action upon the respiration ; anesthesia is more quickly produced, and its solutions are slightly antiseptic. Solutions of the drug are made in distilled water ; the full dose is gr. 1 to |-. The reader, of course, at once draws the correct inference that Schleich's method gives promise of safety. Applications made hypo- dermatically of the elaborated prescription presented are not without danger even in physiological dose. It is necessary that the field of operation be made aseptic before injection. The mouth should be washed repeatedly with a powerful antiseptic, 3 per cent, pyrozone, 10 per cent, electrozone, or 3 per cent, formaldehyd solution. The syringe should be aseptic ; repeated washing of syringe and points in a 25 per cent, solution of phenol sodique will serve this end without detriment to the syringe piston or the metallic parts of the 522 LOCAL ANESTHETICS AND TOOTH EXTRACTION. syringe. A syringe having stout finger-rests and holding about a dram is employed. The needles should be reinforced for half their length, and should have sharp, fine points. The gum is to be dried and touched with a 20 per cent, solution of cocain ; in five minutes the needle may be inserted painlessly. The syringe is filled with the analgesic solution, the needle screwed on, and the piston pressed down until all air is expelled from the syringe and needle. The latter is now thrust into the gum about midway between the neck of the tooth and the apex of the root, until it comes in contact with the alveolar process, when it is slightly withdrawn and a few drops of the solution are driven into the tissues. A second injection is made over the apex of the root ; if the strong solutions be used, the amount of fluid injected must not contain more than gr. \ of cocain ; even though several punctures be made. Care must be exercised to confine the injection to the tissues of the gum ; if the submucous tissue beneath the junction of the cheek and gum be injected into, alarming emphysema may result. For multirooted teeth an injection is made over each root. If Schleich's solution be employed, a full drachm of fluid should be in- jected, until the gum over the tooth is tense and white, when extrac- tion may be accomplished painlessly. In some instances, the intense anemia present at the moment of extraction may be succeeded by local hemorrhage as soon as reaction is established. An antiseptic hemostatic should be applied to the alveolus after extraction ; phenol sodique, full strength, is an admirable agent for this purpose. The imminent dangers to be feared in this connection are : first, the toxic effects of the drug. As these are usually manifested in contrac- tion of the blood-vessels the antidote is amyl nitrite. A supply of pearls each containing TTliij of amyl nitrite should be kept in the medicine cabinet. When a patient exhibits great pallor, a small pulse, and bluish- white lips, one of these pearls is crushed in a napkin and the nitrite quickly inhaled. The conjoint administration of gtt. xx. aromatic spirits of ammonia, or about half an ounce of brandy, is advised. Should these measures not prove promptly effective, artificial respiration should be immediately begun and be prosecuted vigorously. The second danger is septic infection, either through imperfectly sterilized instruments or by carrying septic organisms from the mucous membrane covering the gum into the deeper tissues during the opera- tion of injection. This is avoided by a careful sterilization of the syringe before it is used, and the repeated apj)lications of antiseptic mouth-washes previous to injection. Prescriptions which contain a large percentage of carbolic acid are liable to cause sloughing. EUCAIN. 523 Injections forced between the periosteum and bone may produce serious injury. The introduction of eucain as a local anesthetic was due to the observed chemical similarity of that synthetic body with cocain ; an instance of presaging the physiological effects of a drug by its chemical composition. Its local effect upon blood-vessels is to produce hyper- emia, instead of the ischemia induced by cocain. It is less poisonous than cocain and its solutions are chemically more stable. Its primary action upon the central nervous system is one of exaltation, and this is followed by paralysis, the effect being central, not ascending. The sedative central influence causes a quickening of the heart-beats through sedation of the inhibitory (pneumogastric) nerves. Although eucain is less toxic than cocain it also produces a greater degree of analgesia ; so that the dose need not be greater than that of cocain, about ^ to f of a grain being the maximum. Eucain may be kept in permanent and stable solutions in distilled water. A 10 per cent, solution may be made in distilled water (48 grains of eucain hydrochlorid to the ounce of distilled water) and the solution sterilized by boiling, which does not decompose eucain. From five to eight minims of such a solution is a proper dose. The precau- tions to be observed and the mode of application are the same as for cocain. The hypodermatic use of alkaloids is a distinctly more dangerous method of rendering the operation of tooth extraction painless than is the administration of the safest of anesthetics, nitrous oxid. CHAPTER XX. PLANTATION OF TEETH. By Louis Ottofy, D. D. S. The transplantation of a tooth signifies the insertion of a nat- ural tooth into a natural alveolus other than the one it originally occu- pied. The tooth may be an old and dry specimen transplanted into an alveolus from wiiieh a tooth lias been recently removed, or it may be a freshly extracted tooth transplanted from one part of the mouth of an individual to another part of the mouth of the same individual, or it may be a freshly extracted tooth transplanted from the mouth of one person into that of another. Replantation signifies the replacing of a tooth in the alveolus whence it had been removed by design or accident. The operation may be performed at once or at any time before the socket is filled with new tissue. Under the term implantation are included all those operations which involve the formation of an artificial alveolus for the reception of the root of a human tooth. The operation of altering the size or form of an existing alveolus to receive a tooth belongs to this class, although it is a combination of trans- and implantation. The operation of replantation probably far antedated that of trans- plantation, as the latter preceded implantation, but its definite history is unknown. It is safe to presume that it has been practiced ever since mankind conceived of the natural healing power of the body. Even when perfijrmed with crudity and without any clear comprehension of the mode of repair, favorable results have been reported. The ope- ration is at present an uncommon one : the condition for the relief of which it was at one time practiced with comparative frequency, chronic alveolar abscess, has been found amenable to less radical treatment. The operation of transplantation is first noted in the writings of Ambroise Pare in the sixteenth century, though credit has generally been given to Dr. John Hunter, who gave the subject considerable attention. Hunter's experiment of im]ilantiug a tooth in the comb of a cock is classical. The records of the operation do not exhibit any 524 BIOLOGICAL CONDITIONS IN PLANTATION. 525 great measure of success attending it. Hunter noted cases of trans- plantation of dead teeth which remained for years. No one disputes with Dr. Younger of San Francisco the authorship -of the operation of implantation. The date of his first operation was •June 15, 1885, although Bourdet in 1780 was the first to mention the •operation, stating that " irresponsible persons claim to make a socket, and implant into it a tooth." An attempt at partial implantation is recorded in Dental Cosmos, vol. xix. p. 258. In order that an intelligent conception may be had of the intimate nature of the biological conditions which surround the teeth after inser- tion by either of these operations, it is essential to study the general Fig. 477. Fig. 478. I 15 1 A tooth and its normal attachment and vascular supply : 1, 1, Apical pericementum in which is seen the main pericemental artery, 5 : 2, 2, anastomosing blood-vessels or channels of the alveolar walls ; 3, 3, the marginal anasto- mosis of alveolar and pericemental arteries. Conditions following replantation: 1, 1', The pericementum and inflammatory effusion between pericementum and alveolar walls ; 2, 2, source of blood-supply to the area of repair; 3, 3, terminations of alveo- lar arteries ; 5, obliterated apical artery. processes which attend the repair of tissues, and their behavior toward foreign bodies. As all of these operations are performed under the strictest antiseptic precautions, the consideration of bacterial influence is omitted at this juncture. As it is impossible to secure specimens which would show these several parts in their true relations, the illustrations are neces- sarily diagrammatic and theoretical. ' Figs. 477-480 are from drawings by Dr. H. H. Burchard. 526 PLANTATION OF TEETH. Fig. 477 exhibits a longitudinal section of an incisor, its attachments and support, together with its vascular supply, in its normal relations, the blood-vessels from the pericementum anastomosing with those of the alveolar periosteum. The pericemental space is filled with fibrous tissue. To avoid confusion the nerves and veins have been omitted. Fig. 478 represents the conditions following replantation. The tooth has been sterilized and its pulp canal hermetically sealed. The perice- mental blood-vessels have been destroyed in extraction. Portions of the pericementum are seen clinging as fibrous remnants to the cemen- tum. The remainder of the alveolus is filled with inflammatory corpus- FiG. 479. Fig. 480. Conditions following transplantation : 1, 1', Embryonic tissue which will be organ- ized into repair tissue replacing the original pericementum ; 5, obliterated apical vessels. Conditions following implantation : 1, 1, Alveo- lar arteries ; 2, 2, gingival margin ; 3, inflam- matory still unorganized tissue filling the space between the cementum and walls of the artificial alveolus; 4, 4, phagocytes, mul- tinucleated cells attacking cementum of im- planted tooth ; 5, obliterated apical vessels. cles. The vascular supply to the regenerated pseudo-pericementum is derived first from the vessels of the alveolar periosteum via the alveolar process. Fig. 479 shows the conditions existing soon after the operation of transplantation. The mechanical violence of extraction has irregularly enlarged the natural alveolus. The tooth, its apex rounded, is shown with the blunted extremity. The vascular supply is similar to that of Fig. 478. The alveolar space is filled with inflammatory corpuscles. REPLANTATION AND TRANSPLANTATION. 527 Fig. 480 exhibits the conditions probably existent soon after an implantation operation. The vascular supply is the same as shown in Figs. 478, 479. Instead of having a layer of periosteal bone, the for- mation of the artificial alveolus is into the spongy medullary bone. The artificial alveolus, being necessarily different in size and outline from the tooth, is filled with inflammatory products. Some of the cells, becoming multi-nucleated, are seen to be exercising their phagocytic — or, in this connection, resorptive — function upon the cementum. Replantation and Transplantation. Replantation. — In the present state of dental practice the following conditions may be regarded as warranting replantation : (1) When a tooth has been dislodged by traumatism, a blow, by a ball, club, or fall, etc. (2) When a tooth has been accidentally removed by the slipping of the forceps during the performance of a dental extraction. (3) When some disease, otherwise incurable, aflPects either the root or some portion of its alveolus. The first two causes are practically the most frequent under which replantation is justifiable. In case a tooth has thus been dislodged and found, it should at once be cleansed of all foreign matter and then be carefully examined for fractures or other injury. Any cavities present should be filled, the contents of the root canal removed, and the space filled in the manner described later ; fractured or abraded portions or surfaces are to be made smooth, and the tooth placed in an antiseptic solution. A careful ex- amination of the socket should then be made. It will be noticed when the accident has befallen a young individual, that as a result of the flexibility of the bone, the alveolar process is seldom fractured — an accident more prone to happen in adult life. Some discrimination should be exercised as to the promptness with which to replant the tooth. If there is considerable inflammation as the result of injury, it is not advisable to immediately replace the tooth. In that event the socket should be made aseptic and if possible normal hemorrhage re-established. As a general rule several days should be allowed to intervene when the inflammation is excessive ; otherwise a tooth may be replaced at any time as soon as it has been prepared. The governing pathological principle is as follows : Immediately after an injury, a certain amount of inflammation takes place and there is retrograde metamorphosis — a destruction or breaking down of tissue ; and this is not the most favorable time to expect re-attachment to take place. As a rule, within a few days a building-up process, constructive 528 PLANTATION OF TEETH. metamorphosis, has set in, and the replacement of a tooth at this time is likely to be followed by more favorable results. This period sets in at any time from three days to a week, the socket being then partially filled ^v^ith active living cells. Just prior to the replacement of the tooth the socket and the gum surrounding it having been cleansed and sterilized, the tooth itself being brought forth from its antiseptic medium, it must be promptly replanted. As a rule, constant but not severe pressure will permit the tooth to assume its original position in the socket, although sometimes it is necessary to remove a part of the apex. It ha])pens occasionally that the location of the tooth and the general surroundings are such that a tooth like this may be retained without any further attachment, but as a rule it is not safe to trust to uncertainties regarding the attachment of the tooth. An impression of the tooth and its neigh- bors can be quickly secured with Melotte's compound or in clay, a die is easily made, from which a cap, such as will be described, is quickly made. It is needless to dwell upon the second cause mentioned. No dentist can ever be excused for accidentally removing a sound tooth, but in case the accident does happen the above procedure is indicated. The opportunities enumerated under the third section are also, for- tunately, exceedingly rare. The cases in which formerly replantation w'as resorted to, on the ground that the case was incurable, are now much less frequently met wdth, and when they are encountered they often yield to treatment, wdiich is now more clearly understood — such as amputation of the root, removal of the necrosed jiortion of the alveolar process, etc. When, however, it has been decided to extract a diseased tooth and to replant it, diseased portions of the root should be removed and a sufficient time allowed to elapse before replantation for the socket and tissues to have assumed a healthy aspect, even if this should necessitate the enlargement of the socket. In cases of pyorrhea alveolaris, which sometimes has been suggested as coming under this class, treatment by rei)lantation is out of the ques- tion, provided the case has made sufficient progress to suggest such a course. Replantation implies the presence of a socket, and when pyorrhea alveolaris has made any great degree of progress, the socket is wanting. Hence it is but in rare cases that an attempt to cure by this method is justifiable. Dr. Louis Jack ' has recorded marked success in several cases at- tending an operation of modified rej)lantation for the cure of some of the earlier phenomena of ])hagcdenic pericementitis, n<)taV)ly the com- mon malposition due to what has been termed voluntary tooth move- ment. ' See IVann. Academy of Stumatoloyy, 1895. PREPARATION OF THE TEETH FOR PLANTATION. 529 Transplantation. — There is a broader range for the practice of transplantation than either of the other operations treated in this chapter. As has been seen, replantation is limited in its application, and implantation must, from the nature of the operation, be also con- fined to a comparatively circumscribed sphere. The operation may be performed at any period of an individual's life, although as a rule young, vigorous, and mature adult life offers the greatest promise of success. Any socket in any part of the mouth, when placed in a healthy condition, is a more or less favorable location for the reception of a tooth about to be transplanted. It is true that sometimes a socket needs to be enlarged or deepened for this purpose, but this is a comparatively simple matter. Before the advent of the intelligent practice of crown and bridge work, treatment of diseases of the pulp and peridental membrane, and the bleaching of teeth and the intelligent practice of orthodontia, transplantation was resorted to as a remedy for the correction of many trivial disorders. In the light of the present day, transplantation is confined to sockets whence teeth have been removed for any cause which could not be remedied by some other method of treatment : sockets which remain as the result of the loss of teeth from accident of any kind (the lost teeth not having been recovered) ; from which roots beyond salvation have been extracted ; from which diseased teeth must be removed ; from which roots have been removed having carried crowns or having served as abutments for bridges until their period of usefulness has passed. The same rule laid down for the care of a socket previous to re- plantation holds good for transplantation ; namely, that inflammation must be reduced, and the tooth transplanted into the socket at a time when progressive constructive metamorphosis is taking place. This period is stated as usually from three to seven days after the removal of the tooth. In instances where considerable disease, such as a chronic alveolar abscess of years' standing has been present, even a longer time should be allowed to intervene before transplantation. Preparation op the Teeth for Plantation. With the exception of such special directions as are necessary in each class of the operations described in this chapter, the following general directions are applicable to all cases. The Scion Tooth. — For replantation a recently dislodged tooth is supposed to be at hand, hence there is a fresh tooth. For transplanta- tion it is implied that the tooth is either at hand or about to be secured, but in a case of transplantation or implantation the age of the tooth may be unknown and indefinite. Teeth have been planted whose age and origin have been absolutely unknown, and they have become firm 34 530 PLANTATION OF TEETH. in their new locations. Nevertheless it seems reasonable to take the ground that whenever it is possible, teeth should be fresh and something of their previous environment should be known. There are no cases on record where disease has been transmitted through the medium of a planted tooth, although portions of the early literature of this subject do indicate such results. The principal objection to old and dry teeth is that, the water having been evaporated, these teeth are almost invaria- bly fractured or cracked from shrinkage. When these fractures extend to the crown portion, the enamel frequently chips off within a short time after the tooth has been planted ; while in some instances the entire root has been fractured. Another objection to teeth promiscu- ously gathered, is that it is seldom possible to find teeth in which the crowns are sufficiently perfect to be serviceable and to be presentable in the mouth. The crown of a dry tooth permits of but slight altera- tion with the grinding stone or sandpaper disk without endangering its integrity ; while if it is affected by caries to such an extent as to require an extensive operation, the life of the filling is likely to be of shorter duration than a similar operation performed on a freshly extracted tooth or a tooth with living connections. For this reason it is preferable to use only the roots of teeth, attaching to them artificial crowns. This permits the selection of a crown suitable in size, color, and shape, and which permits of being ground for articulating purposes, an important matter in these cases. If therefore an old, dry tooth must be used, let it be carefully selected with a regard to the absence of checks or cracks or fractures, and if it is impossible to secure a tooth with such a crown, let there be selected a good root to which a crown, as described later, can be attached. If a freshly extracted tooth can be secured, even though the crown may be slightly carious, the necessary filling operation is advisable, and such a tooth should be used, if possible. Root-filling. — Roots may be filled either from the apex or through an opening or cavity in the crown. Gutta-percha seems to answer all the necessary purposes, but for a short distance from the apical extrem- ity it is well to fill with gold wire or foil. Pericementum. — The theory that the pericementum becomes revivi- fied does not seem to be tenable ; at least the proposition that life is maintained in the ])ericementum for any period of time after the tooth has been removed from vital attachment is not in accord with gen- eral physiologic laws, although periosteum as a tissue maintains its vitality for some period after separation.^ For the purpose of securing a living attachment there is no necessity for the presence of the perice- ' See Ziegler's General Pathology. PREPARATION OF THE TEETH FOR PLANTATION. 531 mentum ; but it is reasonable to assume that the nearer to natural states the root and the socket are in, the more favorable is the prognosis. It is, therefore, a safe rule to follow, to preserve as much of the perice- mentum as is possible. The preservation of the pericementum has an advantage from the fact that after the tooth has been planted, the peri- cementum under the influences of bodily heat and moisture expands and thus acts in the nature of a sponge graft, enabling the tissues to more quickly obliterate spaces which are present and to attach them- selves to the root. Subsequent Care of Planted Teeth. — Numerous methods for the retention of planted teeth have been recommended by various authors at different times. While many of them are original and ingenious, all are to be condemned except those means which look to the firm, rigid, immovable retention of the planted tooth for a definite period, that of surgical repair. Neither the rubber-dam splint, silk ligature, nor gold or other metal wire comes under this heading. Planted teeth must be retained immovably for a period of two to six weeks, occasionally from two to eight, ten, or twelve w^eks. The shortest time of immobility consistent with subsequent attachment is preferable. The tooth to be transplanted or implanted should be fitted after preparation in a model, made from an impression of the gum where the tooth is to be planted, and of the adjoining teeth, as shown in Fig. 481. An impression is then taken of it and of the adjoining teeth on each side. A retention cap is then swaged to cover the grinding surfaces of three or more teeth, half the length of the crown on the labial surface and nearly the full length on the lingual or palatal surface, as shown in Fig. 482. Fig. 482. Model showing prepared tooth in place : Model sliou ing retention cap a, Gold filling at cervical joint. in situ. The cap may be made of pure gold, platinum, or German silver. The gauge, according to the metal used, should be from No. 32 to No. 38. This cap is cemented upon the crowns adjoining the planted tooth in such a manner that it may be removed without disturbing the 532 PLANTATION OF TEETH. planted tooth. The operator can remove the cap by springing the metal away from the teeth, examine the condition of attachment of the ])lanted tooth, and replace the cap if it should be necessary. Where the articulation interferes with the retention of the cap, the latter may be ligated to the adjoining teeth in addition to being cemented to them, and still admit of removal without disturbing the planted tooth. There is at present no method of ligaturing or banding the teeth which will permit removal of the ligature or band without more or less disturbance of the planted tooth. Aside from the necessity of inimol)ility for a certain period, the planted tooth and surrounding tissue generally require but little atten- tion. In occasional cases the tissues may be stimulated, l)y painting the gum with a mixture of equal parts of tincture of aconite root, chloroform, and iodin paint (the latter is a saturated solution of iodin in alcohol), or by the use of stimulating mouth-washes, notably those containing capsicum. The patient should be cautioned to encourage the downward growth of the gum by the use of the toothbrush, to prevent the accumulation of remnants of food or saliva, and to pre- vent their subsequent putrefaction should particles become unavoidably lodged around the tooth or cap. This is best accomplished by using a camel's-hair brush dipped in hydrogen dioxid or pyrozone, electrozone, meditrina, etc., washing out the interstices frequently. A syringe or spray from an atomizer may be used. Artificial Roots. — Experiments have been performed looking toward the use of roots other than those of natural teeth. Roots made of ivory, corrugated or perforated porcelain, lead, gold, platinum, and other metals have been used. The writer's experiments in this direc- tion have all resulted in failure. There is no recorded evidence that any have resulted successfully. Mode of Attachment. — As to the mode of attachment of planted teeth the subject is clouded in obscurity. From the nature of the con- ditions it is difficult to secure definite information. Dr. Younger holds to the belief that the pericementum becomes revivified and hence the attachment is almost physiological. Others maintain that the filling of the space around the root of the tooth with compact bone tissue is sufficient to account for the retention of the tooth. In the appear- ance of planted teeth which have failed there should be found the best illustrations of the causes of success. It is ])roV)able that a planted tooth, by reason of the absence of the cushion formed by the living pericementum, causes more or less irritation in the socket ; that this irritation leads to resorption of the root; that in this resor])tion and the subsequent filling up of these resorbed surfaces are found reasons for the success of the operation. Fig. 483, at a, a, shows how a par- PREPARATION OF THE TEETH FOR PLANTATION. 533 tially resorbecl root may be retained in place. The length of time during which a planted tooth is retained depends entirely upon the rapidity of the resorptive process and the activ- ity of the tissues in maintaining a healthy con- Fig. 483. dition. Replanted and transplanted teeth have been known to do good service for from twenty to forty years. The time of the observation as to implanted teeth is shorter, the oldest cases being less than twelve years old. In the writer's observations, extending over a period of nearly ten years, a number of teeth have been noted which have been retained successfully for that ^^ implanted tooth m period; how much longer they will remain ser- «««.• a, a, excavations of ,, , , „ .,, ttie cementum due to re- viceable, and what percentage oi success will sorptive process. attend later cases, will require further time to determine. Dr. Younger has had successfully implanted teeth under observation for eleven years. Precautions. — There is no special danger connected with any of the operations described in this chapter, provided the usual antiseptic pre- cautions are observed and dane-erous anesthetics avoided. Aside from these, during the operation of replantation and transplantation no special skill is necessary. During the operation of implantation cer- tain precautions are essential. Inasmuch as implantation is an essen- tially esthetic operation, it should be borne in mind that it is confined principally to the ten anterior teeth and that it is more frequently per- formed in the upper jaw than in the lower. The territory involved is therefore limited. The operator who contemplates forming in this territory a socket for the reception of the root of a tooth, should be intimately acquainted with the anatomical and histological relationships of the various parts. In the first place it should be remembered that where alveolar resorption has taken place, the relative depth of bone is considerably less than where a tooth is still in situ and surrounded by the abnormal alveolar process. The operator must therefore not penetrate deeper into the bone than the original depth of the socket may have been. Indeed, it is not as a rule necessary to penetrate so far. In the upper jaw the principal danger in making a socket for the reception of central incisors lies in the proximity, posteriorly, of the anterior palatine nerve, artery, and vein, which have their exit from the bone through its foramen, often near the roots of these teeth. With the lateral incisor the principal precaution necessary is the preservation of the labial plate of the alveolus. If the lost tooth has been absent for some time, and much resorption has taken place, it is sometimes im- 534 PLANTATIOX OF TEETH. possible to drill a socket so that the tooth has a proper direction and prominence in the arch, and vet be able to secure a bone cov'cring for its labial surface. As a rule there is sufficient process in the cuspid region to enable the operator to secure all the attachment desirable. The bicuspid and molar regions present the danger of perforation of the floor of the maxillary sinus. This is liable to happen anywhere from the first bicuspid to the second molar. Extreme caution should be ex- ercised to avoid it. In two instances in practice the perforation was fol- lowed by no unpleasant complications. Care was taken not to infect the sinus, the teeth were implanted in the usual manner, and the cases re- sulted successfully. Subsequently one of these teeth was lost, but dur- ing the process of root attachment or encystment the perforation into the sinus was closed. In the lower jaw the principal difficulties encountered are the follow- ing : In the incisive region there is a deficiency of alveolar process, and hence much difficulty is encountered, at times, in securing a sufficiently deep bony socket. At the location of the cuspid tooth the lower jaw becomes broader and there is usually sufficient room to enable the making of a good socket. In the bicuspid region the principal pre- caution necessary is in regard to the mental foramen. It must be borne in mind that normally the exit of the nerves and vessels at this point is directly below the second bicuspid tooth and that when resorption of the alveolar process has taken place this foramen is often near the upper border of the jaw. From this point posteriorly implantations are rarely performed, and when done the principal precaution must be in regard to the inferior dental canal, which is near the surface if much resorp- tion has taken place. Artificial Cro"wns. — The precautions necessary in the selection of a tooth for transplantation or implantation have been noted, and it might be proper at this time to describe the prepara- tion of a root with an artificial crown, presuming that it is only in rare instances that a suitable entire natural tooth can be obtained. Attention was called to the necessity of securing asepsis of the root, and the filling of the root-canals has been described. The most suitable form of crown has been found to be the Natural root with Loffan, which is ffround to suit the occlusion and artificial crown. '^ ' ^ cemented into the root canal without much regard as to a careful fit at the cervix of the crown to the root. After the cement has hardened, the margin between the root and crown is pre- pared with engine burs, and a filling of gold introduced, making a circle around the tooth. When this is polished down there is a GENERAL CONSIDERATIONS. 535 perfect gold filling level with the root and crown, which is preferable to a soldered band. (See Fig. 484.) General Considerations. Asepsis. — The operations described in this chapter must always be performed under perfect aseptic conditions ; that is, the hands and person, instruments and other accessories, the tooth about to be planted, and the field of surgical operation, must be maintained in a clean aseptic condition. Any of the usual accepted methods can be resorted to. As a rule, however, the drugs selected for this purpose should not be of an irri- tating nature. For the hands and person, pure soap, followed by a 5 per cent, solution of carbolic acid is sufficient. The instruments and other accessories can be kept free from inoculating bacteria by the use of pyrozone, euthymol, or a 5 per cent, solution of carbolic acid. The use of bichlorid of mercury in the proportion of 1 part to 2000 of water is also permissible, although it is not as advisable on account of its irritating nature. The sterilization of the tooth about to be planted differs according to circumstances. A tooth whose source is unknown, and which has been kept in a dry state for a long period, will not be benefited by being placed into an antiseptic solution until just prior to the time when it is to be used. Hence dry teeth can be kept in any clean box covered with clean cotton until they are ready for use. After the necessary preparation hereinafter described, the dry tooth should be placed in a solution of glycerol and carbolic acid (about 5 per cent, of the latter), and just before using, it can be placed in a pyrozone solu- tion or in a solution of carbolic acid and water. Freshly extracted teeth should, of course, have their pulp chambers and root canals cleansed and hermetically sealed, and then be placed at once in fluid, preferably in glycerol to which a few drops of carbolic acid have been added. It is, of course, of exceeding importance that the socket into which a tooth is about to be planted shall be free from disease germs or bacteria. As a general rule flowing blood is the best of antiseptics, washing away any bacteria which may become lodged from external sources, hence so long as a socket is constantly being filled with flow- ing blood during an operation, but little further care need be bestowed upon it. As a general rule the socket and the tissues surrounding it will react more quickly after operation the less the medication has been ; hence the very slightest and mildest of antiseptics are indicated. Zinc chlorid, 2 to 5 grains to the ounce of lukewarm water, or the 5 per cent, solution of carbolic acid in lukewarm water, ffive most satisfac- tory results. These solutions will be found quite sufficient to maintain the field of surgical operation aseptic. 536 PLASTATION OF TEETH. Anesthesia. — For the purpose of allaying pain, the use of anes- thetics is justified Avhen imperatively demanded, but unfortunately, in the plantation of teeth the benefits derived are frequently outweighed by the disadvantages accruing from their use. Anesthetics are either general or local. An operator would scarcely be justified in assuming the risks attendcnt upon the use of chloroform, ethvlic ether, ethyl bromid, or any of the combinations in which these anesthetics are administei'ed. Xitrous oxid would, in the majority of instances, be contra-indicated by reason of the shortness of the period of anesthesia which it induces. There do not appear to be any records of satisfactory results with hypnosis. That field is open to the intelligent investigator whose inclinations lie in that direction. Local anesthesia, therefore, is the means generally employed. The use of cataphoresis with local anes- thetics has not as yet been satisfactory for this purpose. The usual method has been confined to the injection or other intro- duction of cocain, the dose being variable, but usually about 10 to 40 minims of a 4 per cent, solution of the hydrochlorid of cocain. A seri- ous objection to injection through the gum has been noted, viz. that more or less sloughing or destruction of the tissues may result, and this is very unfavorable for subsequent success. In replantation or trans- plantation, sufficient anesthesia is often obtained from the wash used in cleansing the socket ; but in implantation the formation of the new socket is often an exceedingly painful operation, and in these cases good results may be had by dipping the instrument with which the socket is being made, into crystals of cocain, and thus by the friction of the instrument rubbing it into the parts that are being operated upon. The subject of anesthesia may be dismissed with the sole injunction that its use should be resorted to only in those instances where it is absolutely necessary. The majority of the cases of plantation are per- formed with no more pain than is inflicted in filling operations. The same care should be given to the retention of transplanted teeth as is given to the retention of replanted teeth. Teeth thus carefully transplanted, in individuals of good health, often remain as useful members for a number of years. In the past insufficient atten- tion has been given to asepsis, and this, coupled with the fact that the root had not always been properly filled, has not resulted in as much success as is attained with present methods, and yet transplanted teeth are known to have remained in a healthy and serviceable condition for from twenty to forty years. THE OPERATION OF IMPLANTATION. 537 The Operation of Implantation. Implantation, in order to yield the best results, should be confined to mouths which are habitually clean and free from disease, and to a part of the individual's life during which the power of the developed mental processes is not impaired. Unclean personal habits, the ex- cessive use of stimulants, and occupations calling for an unusual ex- penditure of nerve force are unfavorable. A suitable case having been selected, an impression of the space and of the teeth adjoining it is taken. A plaster cast is made, the proper-sized socket drilled therein, the tooth is selected and prepared, either with or without an artificial crown in the manner previously described, the occlusion is adjusted, and a retention cap is made. These preliminaries having been satis- factorily accomplished the case is ready for the operation. Under the heading of General Considerations, the question of anesthesia has been already treated. The first step in the operation is the making of an incision through the gum tissue. A number of different kinds of incisions have been recommended by different operators, nearly all of them looking toward the preservation of the largest amount of gum tissue. Some recom- mend a crucial incision X, turning back the four corners of the gum tissue. Others have recommended an incision in the shape of the lett;er H, turning back the two flaps thus made. The principal objection to all of the incisions recommended lies in the fact that they all look toward the preservation of the gum tissue equally for the labial and lingual surfaces ; while, as a matter of fact, if proper provision is made for the protection of the cervical line on the labial surface, the lingual surface will take care of itself, for it will be noticed in cutting through the gum tissue that it is much thinner where it reflects over the alveolar border upon its labial aspect than upon its lingual. Hence, frequently, if no attention whatever has been paid to the retention of gum tissue on the lingual surface, the neck of the tooth will nevertheless be sufficiently protected. Fig. 485. Incision In gum for implantation. Another serious objection to an incision which leaves two or more points or margins to be preserved, is that the tenacity of the gum tissue 538 PLANTATION OF TEETH. Fig. 486. n Chisels. makes it utterly impossible to preserve intact from the cutting instru- ments these various flaps and projections. The writer's method consists in an incision resulting in one flap, with a view of protecting the labial surface of the tooth to yig. 487. be implanted, and of preserving this single flap from in- jury during the progress of the operation. A combina- tion, or rather a modification, of the most suitable incis- ions recommended is therefore the one shown in Fig. 485. This incision is made with ordinary chisels as shown in Fig. 486, cutting with the chisel to and including the periosteum, lifting it for- ward and holding it out of the way of the operator by means of an instrument similar to the one shown in Fig. 487. The operation thus far is usually sim- ple and as a general rule not very pain- ful. The drilling of the socket varies with different individuals according to the density of the bone, the length of time that the tooth has been out, etc. In some instances the reamer or trephine or knife pro- gresses rapidly, while in others progress is very slow, or sometimes variable as the instrument enters into medul- lary spaces or passes through the more or less dense parti- tions which divide these medullary spaces from each other. The operator will determine during the operation, by the progress he is making with different instruments, which are the best to use. In some instances the entire socket can be made with an ordinary engine bur, while in others the strongest instruments especially designed for implantation are none too strong. In some instances an instrument which clears itself well during one operation clogs annoyingly during another. It is desirable to de- scribe at this point the various useful instruments which have been designed and are now upon the market. While all of them are not necessary, some one or more of each class are indispensable. The trephines of Dr. Younger, of San Francisco, whicih have been im})roved by Dr. W. W. Walker of New York, have (as shown in Fig. 488), a set-screw collar, also shown detached, which slides on the instrument for shank and is first fixed by a set-screw as a gang(> of the during the length (jf the tooth root. As will be noticed the trephines operation. cut only on the edge, and hence they do not entirely clear themselves ; i THE OPERATION OF IMPLANTATION. 539 the reamers described on a previous page are then used to remove the core and enlarge the socket. Fig. 488. 12 3 4 5 Younger-Walker trephines. Fig. 489. Rollins' spiral knives. The spiral knives (Fig. 489) devised by Dr. W. H. Rollins of Boston are in many cases very useful. They are also open to the objection of clogging. As an improve- ment upon these the spiral crib knife shown in Fig. 490 has the advantage of permitting the core to pass within it. Fig. 490. Fig. 491. Ottofy spiral crib knife. 1 2 Two forms of Cryer's spiral osteotome. 12 3 4 5 Ottolengui's reamers. Dr. R. Ottolengui, of New York, has devised a set of reamers (Fig. 492). There are nine leaves to each reamer and each leaf is divided into five teeth. Three of the leaves reach the apex of the cone point and thus allow a more rapid forward drilling into the bone. A sliding collar forms a gauge to indicate the proper depth to drill. 540 PLASTATIOy OF TEETH. The reamers designed by Dr. Younger, illustrated in Fig. 493, are also very suitable for this purpose. Dr. Cryer's spiral osteotome— two forms of which are shown in Fig. 491, one with dentate edges the other without — is an admirable instrument for forming the artificial socket. When it is necessary to deepen or alter the shape of the socket, it is done very simply with either the ordinary burs of the dental engine or, what is preferable, a bur with a long shank such as shoAvn in the accompanying illustration (Fig. 494). Fig. 494. Fig. 493. Dr. Younger's reamers. Li J, ft 1 ^w v'igv 7iji ^ 12 3 4 Engine burs with long shank. The following are to be recommended : Nos. 1 and 3 of the Walker- Younger trephines, Xos. 1 and 3 of the Younger reamers, Nos. 1 and 2 of the Rollins spiral knives, Nos. 1 and 2 of the Ottofy spiral crib knives, and Xos. 1, 3, and 4 of the Ottolengui reamers and Cryer's osteotome. During the progress of the drilling of the socket, the tooth should be frequently inserted until a proper adjustment has been secured. Occasionally these teeth can be implanted and so perfectly fitted that it is almost impossible to remove them with the unaided fingers ; while at times the bone is so cancellated, and the tissues so flabby, that a socket drilled never so carefully w'ill not retain the tooth in place. Nothing is gained by a too close adju.stment of the root, as pressure must un- doubtedly be exerted, and pressure causes resorption, and may be fol- lowed by inflammation. A fair, moderate fitting of the root is all that should be aimed at. Just before the final adjustment the socket, gums, tooth, and all parts contiguous thereto, should be placed in an aseptic condition and the cap adjusted in the manner before described. Planted teeth when lost, are lost as a rule as the result of resorption of their roots. The true cause of the resorption of the roots is unknown. The process seems analogous to the resorption of the roots of deciduous THE OPERATION OF IMPLANTATION. 541 teeth. The present status of planted teeth seems to indicate that resorption of the roots is slowest in progress in replanted teeth. It is more rapid in transplanted teeth and most rapid in implanted teeth. Intelligent observation over replantations and transplantations extends from twenty to forty years. The observation of Dr. Younger of implanted cases extends at this writing to about twelve years, and he has had successful cases under observation which have remained in the mouth over ten years. The writer has the records of cases which have remained and done good service for ten years. CHAPTER XXI. MANAGEMENT OF THE DECIDUOUS TEETH. By Clark L. Goddard, A. M., D. D. S. Eruption. — The first operation the dentist is called upon to perform for the deciduous (temporary) teeth is lancing the gums as an aid ta eruption of those organs. This is not necessary in normal but only in pathological cases. Although gum tissue in its normal condition is. comparatively insensitive, when it is inflamed it is exceedingly tender. The principal source of pain, however, is not in the tissue overlying, but when a tooth, bound down by the dense gum tissue above it, by its. own growth presses upon the formative organ below, it causes pain which in many cases may be so excessive as to cause reflex disorders of alarming character. Dr. J. W. White' says.: " The manifestation of functional inharmony from pathological dentition will depend, as in trouble arising from any other disturbing cause, upon the temperament and health of the child, its dietetic management, and its hygienic surroundings. In some cases, there is a gradual development of biliary, gastric, enteric, and cerebral complications, a slow but steady loss of vital power, with no effort at recuperation and feeble resistance to the undermining influences which gradually but surely wear out the young life. " In other cases the indications of disturbance of function are mani- fested primarily in the nervous system : the symptoms are all charac- teristic of acute derangement and are dangerous from their violence and uncontrollability. High fever, vomiting, choleraic diarrhea, men- ingitis, convulsions, stupor and death are the rapidly succeeding phenomena. Between these two phases there is every conceivable grade of symptoms, every imaginable complication." By many as an objection to lancing the gums it has been urged that, in case the tooth does not erupt immediately, cicatricial tissue is formed over it which will bind the tooth down more rigidly than before. Cica- tricial tissue is, however, of a lower degree of organization than normal tissue, and is more easily broken down. ' Amer. System oj Dentistry, vol. iii. p. 327. 542 ERUPTION. 543 The indications for interference are not so much local as general — the fretfulness, inability to sleep, and other symptoms mentioned by Dr. White. The gum tissue over the erupting tooth may or may not be highly inflamed, but the absence of such inflammation does not con- traindicate lancing. In fact some of the gravest systemic disturbances occur where no local manifestations are evident. The object is to divide the gum tissue which binds down the tooth and to allow it free egress. The most suitable instrument is shaped like that shown in Fig. 495 and sometimes used for lancing around teeth before extraction. It should be held like a pencil in „ . . '- Fig. 495. writmg, so that one or more fingers can form a rest and guide. For operating on the lower jaw the child is best seated in the lap of the operator with the head against his breast. By passing the left arm around the infant's head and in- serting the left thumb in its mouth with the fingers under the chin, the lower jaw can be held rigidly, while the right hand performs the operation. For operating on the upper jaw it is best to lay the child across on the nurse's lap. The operator takes the head on ^ , ^ ^ Gum lancet. or between his knees, opens the mouth by inserting one or more fingers of the left hand, and holding the thumb and forefinger on each side of the alveolar ridge, thus preventing injury to contiguous parts during possible struggles of the child. For incisors a simple longitudinal incision is made a little longer than the cutting edge of the tooth. The lancet should be sharp, so as to easily penetrate to the tooth. No harm will be done except to the blade of the lancet. For the cuspids a single incision is good, but a crucial incision is better. Sometimes lancing is necessary for the cuspid after it is partially erupted, as the gum tissue, pierced by the point only of the tooth, may form a dense ring around this point and interfere with further eruption. In such a case a division of this ring in two or more opposite places will give relief. For the molars a crucial incision is best, one cut extending from the posterior buccal to the anterior lingual cusp, and the next from the posterior lingual to the anterior buccal. Sometimes lancing is necessary for these teeth after partial eruption. After the cusps have pierced the gum, the tooth may be held back by the bands of tissue in the sulci. In such cases division of these bands in the same direction as before described for an unerupted tooth will give relief. Sharp-pointed curved scissors are well adapted to this lat- ter operation. Fig. 496 will illustrate the direction of the incisions described. The 544 MANAGEMENT OF THE DECIDUOUS TEETH. relief afforded is generally immediate. In one case a child who had been fretful for several days, and who had not slept at all during the day, was asleep in the writer's arms within five minutes after the ope- ration. The gum tissue is not very '^' sensitive, so the operation is often .0 painless. The little sulterer will often recognize the relief obtained and point to other portions of the gums for further relief. ^ I ] Duration of the Deciduous ^' "^N?*,^ ^ ^-'' Teeth. — The importance of filling ^^ ' ^ _ cavities in the children's temporary I, teeth is often overlooked, even by Lines of incision in lancing : a, a, over the dcntists thcmselveS, aS tllCSC tcctll are molars ; 6, 6, over the cuspids and incisors i j. i i ^ i x_ before eruption: c, r, cover the molars SUPpOSed tO be lost SO early aS tO and cuspids after partial eruption (J. w. render such Operations unnecessarv. White). rn, . . 11 . , , .' Ihis IS generally true with the in- cisors, is less true with the cus])ids, while the molars often need at- tention. Fig. 448 (Chapter XIX.) shows the relations of the deciduous to the permanent dentures in a child of about six years of age. A study of the following table will show that while the incisors are superseded early by their successors the molars are in place nearly twice as long : Time of Eruption. Loss. Duration. Central incisors 6-8 months. 6th-7th year. h\ to 65 years. Lateral 7-9 " 7th-8th " " " ''■ " First molars 14-10 " 9th-10tli " 7J " 9 " (1 yr. 2 m.-l yr. 4 m.) Cuspids 17-18 " finf. 8th-10th " m yrs.) ISup. 11th- 12th " 7 " 10 " Second molars 18-24 " 12th-13th " 10 "11 " [\\ yrs.-2 yrs.) The temporary molars should be preserved for three reasons : 1st. To prevent the child suffering pain. 2d. To allow proper mastication of food. This latter is of extreme importance, as these years are especially important ones in the child's growth. If he is prevented by pain from properly masticating his food it will not be assimilated, and a habit of swallowing food without masticating may be continued even when the permanent teeth have erujited. 3d. To preserve the fulness of the arch for the permanent teeth. Early loss of the deciduous second molar will allow the first per- manent molar to move forward and occujjy room that should be pre- served by the bicuspids. Early loss of the first temporary molar will ODONTALGIA. 545 allow the second temporary and the first permanent molar to move forward. The crowns of the temporary molars are much larger than the necks of these teeth, and caries of the approxiinal surfaces will allow them to crowd together with the same result. Approximal fillings inserted should be so shaped as to preserve the original contour. If the first permanent molar thus moves forward of its natural position a Fig. 497.1 Decalcification of the deciduous teeth. Tlie numbers indicate years. smaller arch is left for the successional teeth. The result may be a constricted arch, a pointed arch, upper protrusion, or the labial dis- placement of the cuspids. Odontalgia. — The first visits by children are usually for the relief of " toothache," and may occur at any age from two years upward. The first treatment of most children's teeth should be palliative. In many cases a fear of the dentist has been engendered, which it should be the prime object to remove. Make the acquaintance of the little patient in the reception room, talking perhaps of things altogether foreign to the case in hand, and distract its attention. If the child is very timid examine the teeth while it is seated in an ordinary chair, or in its parent's lap, and apply some dressing to relieve the pain. In the operating room the chair should be adjusted to its smallest size ; a special child's seat may be used, or a cushion half the size of the chair seat, and not too soft. The child's head should be made comfort- able in the head-rest. The operator should not let the child detect him in an endeavor to hide instruments ; the necessary ones may be shown to him if they arouse his curiosity, and their purpose explained. On account of the difficulty the child has in making himself under- stood, or from his not knowing what he wishes to describe, diagnosis is difficult. A child cannot always distinguish just where pain is felt, nor always remember its exact location. In most cases the first occurrence of pain is during mastication. ' Prof. Peirce in Amer. Si/stem of Dentistry, vol. iii. p. 639. 35 546 MANAGEMENT OF THE DECIDUOUS TEETH. It is necessary to ascertain whether pain is caused by an erupting tooth, a nearly exposed pulp, a pulp inflamed and dying, a putrescent pulp, or an alveolar abscess. If the nearly exposed pulp is suspected, test it by the application of a drop of cold water. Pain during masti- cation may be caused by thermal changes, by pressure of food in the cavity, or by pressure on a tooth whose pericementum is inflamed. If the tooth is aching while the child is in the chair, syringe out the cavity with warm water, dry it with bibulous paper, and apply a pledget of cotton saturated with oil of cloves, canipho-phenique, or whatever has been found effective with permanent teeth. Fletcher's carbolized resin ^ has been invaluable for this purpose in the writer's practice. Applied on a pellet of cotton it acts as an anodyne, and the resin hardens in the cotton, forming with it a temporary stopping which will even bear the force of mastication for a few days. It is sometimes best to renew this dressing a few times before attempting a more per- manent treatment or filling. If the child cannot be brought to the office again within a few days, let the parent provide himself with a bottle of the carbolized resin and an inexpensive pair of dressing pliers. Instruct the patient how to apply the cotton dressing. This is the best domestic remedy for odon- talgia. Other medicaments may be used by the parent, such as oil of cloves, campho-phenique, etc., but their effect is much more temporary. A more durable dressing may be made by mixing zinc oxid and car- bolized resin to the consistence of putty and applying it in the cavity previously dried. It hardens under moisture, and makes a stopping that will remain, in some cases, for several weeks. During such palliative treatment, sometimes unavoidably extended over several weeks or even months, the child is growing older, is gain- ing experience, is becoming used to manipulation, begins to recognize the benefit of treatment of the teeth — in a word, is being trained or educated for a good patient for whom more permanent operations may be attempted. Prof. li, L. Dunbar says : " As a domestic palliative always at hand, in the treatment of pulp exposure and restricting odontalgia, use ammonia on cotton : its repeated use will devitalize the pulp, at the same time effecting its removal by saponification." Treatment with Silver Nitrate. More than forty years ago the application of silver nitrate for arresting decay was advocated, but for many years no notice was taken ' Carbolic acid, Resin (colophony), da. ,f j ; Chloroform, f.fss. TREATMENT WITH SILVER NITRATE. 547 of it. Within the last five years it has Ijeen advocated again, especially for use in the temporary teeth. The fact that it blackens the decayed surface is not as objectionable as with permanent teeth. Dr. Stebbins^ advocated the use of a solution of the crystals of silver nitrate in cari- ous cavities in temporary teeth. He applies it by means of a small stick inserted in a socket instrument as shown in Fig. 498. Many Fig. 498. cases will need no further treatment, decay being completely arrested. Some cases will need secondary treatment after a few months. In many cases he advises filling the cavity with gutta-percha after the application. Dr. C. N. Peirce^ advises saturating pieces of blotting paper with 40 per cent, solution of silver nitrate, and keeping these on hand for use. Dr. E. C. Kirk advises the use of asbestos felt for saturation with the solution in preference to blotting paper or cotton. He says :^ " The contact of silver nitrate with vegetable fiber of any sort involves not only a destruction of the fiber but also of the silver nitrate, so that the preparation in a short time loses its desirable qualities." He advises that the asbestos felt be heated before the blowpipe before saturation, to burn out any organic material which may be present. Dr. A. M. Holmes * advises its use as follows for approximal cavities : " Cut away the walls to a V shape, and with a piece of gutta-percha, softened by heat, of the proper size to fill the space, bring the surface to come in contact with the diseased part of the teeth, in contact with the powdered crystals of silver nitrate and carry it to the place in the tooth or teeth prepared for its reception, packing it firmly and leav- ing it there to be worn away by use in mastication. When that takes place, the surfaces of the teeth treated will be found black and hard, with no sensitiveness to the touch or to change of temperature, and they will remain so indefinitely. In case the child is so timid as to prevent this course, dry the cavity, take out as much softened dentin as the patient will permit, carry the crystals on softened gutta-percha into the cavity and pack it, leaving it until such time as desirable to make a more thorough operation." ^ International Dental Journal, 1891, p. 661. * Ibid., 1893, p. 152. 2 Dental Cosmos, 1893, p. 667. * Ibid., 1892, p. 982. 548 MANAGEMENT OF THE DECIDUOUS TEETH. In the writer'.s opinion it is better to open approximal cavities from the occlusal surface rather than make V-shaped spaces, as the full diameter of the teeth should be left to preserve the fulness of the arch. Silver nitrate in its action penetrates but a short distance. The Character of the Patient. The conditions of operating on the deciduous teeth vary so much from those pertaining to the permanent teeth that a different consid- eration must be taken of filling materials. The little patients' mouths are small. They are often too young to reason with or to understand the purpose of the operation. They have been too often frightened ])y thoughtless remarks of their elders in speaking of their dentist. Oftentimes the first sitting must be utilized merely to make the acquaintance of the child, perhaps cleaning the teeth a little, or intro- ducing some palliative dressing in an aching tooth. The greatest care should be taken not to hurt the child. After it has gained a little experience it recognizes the benefit of the treatment, and will often submit to operations that older patients even shrink from. Filling Materials. Gutta-percha. — Pink base-plate gutta-percha is a most valuable filling material. In approximal cavities where it is not exposed to wear and where the shape of the cavity is such as to retain it, it is practically indestructible. In approximal and occlusal cavities in which it is exposed to wear it has wonderful durability, lasting in some cases for several years. Directions for Use. — Cut the gutta-percha in small pieces and place them on a gutta-percha Avarmer (see Fig. 237), where they can be kept soft but not heated enough to injure the material. The instruments also should be warmed (see Fig. 226), Occlusal Cavities. — Cut away the margins of thin enamel with suitably shaped chisels, and remove the decayed and softened dentin with scoop and hatchet excavators. Do this as thoroughly as the patient will permit, but do not sacrifice the patient to thoroughness, for the thorough removal of softened dentin is not as essential as with per- manent teeth, because the gutta-perclia is, by mastication, ke})t in such accurate contact with all of the walls of the cavity that further soften- ing will go on very slowly if at all. No special attention need be paid to the form of the cavity, except that its mouth should not be larger than the rest, nor should any parts of the cavity be inaccessible to the FILLING MATERIALS. 549 filling material. After excavating, dry the cavity with bibulous paper, and apply campho-phenique, oil of cloves, or carbolic acid, to sterilize any softened dentin which may not have been removed. For drying cavities, prepare paper cylinders, of different sizes, as follows : Tear the bibulous paper in strips from half an inch to two inches in widtli. Roll or twist each of these strips into a rope, but not too tightly — just enough to retain the shape. Cut these ropes into cylinders from a quarter to half an inch in length. Some of these will be as large around as a lead pencil and others no larger than the lead itself. Protect the tooth from moisture as well as possible. For lower cavities fold a small napkin diagonally from the corner till it is about half an inch wide. Put the end of this between the gum of the upper cuspid and the lip and extend the napkin back between the upper molars and the cheek beyond the last tooth, then down behind the last lower molar, and press it between the lower teeth and tongue. Tell the patient to raise the tongue as it is applied, then to lower the tongue and hold the napkin with it. The part of the napkin between the upper teeth and the cheek will cover the mouth of the duct of Steno, and prevent or absorb the flow of saliva. It is better to cover the mouth of this duct with a piece of spunk about half an inch in diameter before applying the napkin. The folds of napkin between the lower teeth and tongue and under the tongue will absorb the saliva from the submaxillary glands. This part of the napkin can be held in place with a mouth mirror or other blunt instrument, by the operator or assistant. After applying the napkin use a large bibulous paper cylinder to absorb the moisture from the tooth to be filled and also from contiguous ones. With smaller cylinders or pellets dry the cavity. Apply once more campho-phenique or other medicament, and absorb the excess. The gutta-percha having been meanwhile warmed and softened, pick up a small piece of it with a cold round-pointed instrument and press it into the cavity. If the cavity is not large, a single piece of gutta-percha of a diameter less than that of the cavity, but longer than the cavity is deep, can be pressed in quickly and at one movement. For medium-sized cavities select a piece of gutta-percha large enough to cover the floor of the cavity and press it into place with a cold instrument, as a warm instrument might drag it from its place. Add similar pieces, pressing each one to the place in which it is to remain, till the cavity is full. If at any time the gutta-percha in the cavity becomes so hard as to lose its plasticity, apply a warm instrument to soften the surface, so that the next piece will adhere to the others. As the filling nears completion select a small piece for the last, just large enough to complete the filling and no more, so that none will 550 MANAGEMENT OF THE DECIDUOUS TEETH. have to be trimmed away, for in trimming the siirpkis away the filling may be drawn from contact with the walls of the cavity. In filling large cavities it may be necessary to hold the first piece in position with another instrument till sufficient material is added for self- retention. At the completion of the filling slight pressure with a warm instrument should be made in such a manner as to force the material ao-ainst all the margins of the cavitv. Approximal Cavities. — Where possible, approximal cavities should be opened from the buccal surfaces, as advised by Dr. Bon- will, as in such cases gutta-percha fillings will not be exposed to the force of mastication. This plan is not often practicable because the patient is seldom presented till the cavity has become visible by open- ing into the occlusal surface of the tooth. In such cases cut away the enamel only enough to give access to the cavity, excavate the decayed dentin, and trim the buccal, lingual, and cervical avails until a smooth, firm margin is obtained. In filling such a cavity use small pieces of softened gutta-percha, pressing each piece where it is to remain, and avoid a surplus. Press the gutta-percha against the adjoining tooth as if it were a matrix or a fourth wall of the cavity and let it remain.' It is useless to trim it away from the adjoining tooth, because the force of mastication would soon spread the filling against it again. If an approximal cavity cannot be readily shaped so that it Mill retain the gutta-percha, it may be packed against the adjoining tooth, as if it were an occlusal cavity. It will prevent decay, especially if silver nitrate is applied as described on page 546, and may be retained till the patient is older, when a more thorough operation may be per- formed. The spreading of the gutta-percha by the force of mastication will tend to separate the teeth — which is sometimes an advantage ; and also to press upon the gum in the interproximal space — which is a disad- vantage. In filling children's teeth we cannot always reach the ideal, but must select the method and material which will have the greatest advantage with the least disadvantage. If the teeth separate so much that the pressure of the gutta-percha upon the gum tissue becomes a serious annoyance, some other material must be substituted. Zinc phosphate cement is probably the best. Advantages of Gutta-percha. — It is easily applied to the cavity ; it is insoluble ; is durable even when masticated u])on ; is a non-conductor of thermal impulses ; the filling is finished as soon as the cavity is full ; it spreads under the force of mastication, and is thus kept in contact with the walls of a cavity ; it can be used even under moisture. Disadvaidayeis. — Gutta-percha is softer than other filling matei'ials, FILLING MATERIALS. 551 and hence wears away more rapidly. In approximal cavities it will spread the teeth apart, and may then press upon and irritate the gum. Dryness of the caVity, though very desirable, is not absolutely neces- sary. Advantages of Zinc Phosphate Cement. — It is a poor conductor of heat ; it withstands the force of mastication better than gutta-percha ; it adheres to the walls of the cavity, and hence will remain where no other material can ; it is easily applied ; its color may be selected to match the tooth. Disadvantages. — Absolute dryness of the cavity is a prerequisite to its success ; it must be kept dry for several minutes after it is inserted in the cavity. Zinc phosphate cement disintegrates in some mouths much more rapidly than in others. If placed too near the pulp it may by chemical irritation devitalize it. Application of the Rubber Dam. — AYhile many hesitate to attempt the use of the rubber dam with children, it will be found upon trial that most of them will submit to it without trouble, and many will prefer it to other means of keeping cavities dry. Although there is an advantage in applying the rubber dam before excavating — because dryness makes the teeth less sensitive, and a clearer view of the cavity is obtained — still, for the sake of not tiring the little patients by too long restraint in one position, it is better to do most of the excavating before its application. The small size of the necks of the deciduous teeth compared with that of the crowns renders the retention of the rubber dam easier than with permanent teeth. Even considering the smallness of the patients' mouths, the application of the rubber dam is not difficult in many cases. For retaining the rubber dam on the second molar a clamp will sometimes be necessary, but for the other deciduous teeth a floss silk ligature will be sufficient. Having punched holes of suitable size through the rubber dam, apply it over the teeth affected. If the cavity is in the occlusal or buccal surface only, it will not be necessary to apply it over more than one tooth, but if the cavity is in the approximal surface it will be necessary to apply the rubber dam over two or some- times three teeth, or even more, if several cavities are to be filled at one sitting. It is not always necessary to tie a ligature around the neck of the tooth, as merely passing the waxed floss silk between the teeth will often force the rubber around the neck of the tooth enough to retain it even above an approximal cavity. The silk may then be removed by drawing the end through between the teeth. With a thin burnisher or spatula turn up the edge of the rubber 552 MANAGEMENT OF THE DECIDUOUS TEETH. around the neck of the tooth toward the gum. The tendency of the rubber then will be to slide in that direction and not oiF over the crown. If a ligature be necessary to hold the rubber above the edge of an approximal cavity tie it tightly around the neck of the tooth, even forcing it toward or under the edge of the gum with an instrument when necessary. The clamp on a second molar may often be dispensed with after a ligature is applied, unless it is needed to hold the rubber out of the operator's way. The only object in omitting the clamp is to pre- vent pain or discomfort to the child. If a simple ligature will not retain the rubber on a second molar before the first permanent molar has appeared, its efficiency may be greatlv increased by stringing a bead, about an eighth of an inch or less in diameter, on the thread and tying a simple knot in it so that the bead will be in about the middle of the ligature. Tie the ligature around the tooth so that the bead will lie against the distal surface of the second molar on or near the gum. This bead will prevent the rubber slipping off the tooth. A short cylinder of bibulous paper can be tied in the ligature and applied with the same effect, and even a large knot in the ligature on the distal surface of the tooth will often answer the purpose. The corners of the rubber dam should be held out of the way by a suitable holder extending around the head (see Fig. 147, Chap. VII). The lower border may be held out of the operator's way by small weights, hooked in the edge. Dry the cavity and the whole tooth or teeth, and complete the excavation. Filling" Cavities with Cement. — As cement can be applied easily in undercuts and very irregularly shaped cavities it is not necessary to cut away the enamel more than is sufficient to enable the operator to thoroughly remove the disintegrated dentin. Even the thorough re- moval of the latter is not as essential for a cement filling as for other materials, for, if the edge of the cavity can be made smooth and the softened dentin be thoroughly sterilized, the cement will hermetically seal it and prevent further disintegration until it is worn away beyond the sound edges. The operator may take much greater risks in leaving disintegrated dentin tlian with permanent teeth, for the object is simply to retain the tooth till the time arrives for its successor to appear. It must be remembered in excavating cavities in deciduous teeth that the pulp is much larger in proportion t«j the size of the crown than in permanent teeth, and that in trying to make undercuts or retaining grooves deep enough to retain a filling, the pulp may be exposed — an accident which should be carefully guarded against, for the ])nlp has FILLING MATERIALS. 553 not even the recuperative power possessed by the pulp of a permanent toothy and in case of its death it is more difficult to give a deciduous tooth proper treatment. Moreover, death of the pulp prevents normal resorption of the root and may thus cause irregularity of the permanent teeth. For most cases the cement should be mixed as thick as can be easily and quickly manipulated, but if the pulp is nearly exposed the cement should be used so thin that it can be applied without pressure, by flowing it over the floor of the cavity. Cement mixed moderately thin will adhere better to the walls of the cavity than when it is as thick as it is possible to apply it. The thinner the cement, the longer time it will take to harden, but the thicker it is mixed the more dur- able it will be. Do not keep the little patient in a constrained posi- tion longer than necessary. The easier the first operation is for him the more readily will he return for the second. If the pulp is very nearly exposed apply Fletcher's carbolized resin over the floor of the cavity. For this purpose remove the stopper of the bottle till by evaporation the carbolized resin has thickened to the consistence of molasses. Dip a small probe in this thickened mass, so that a small drop will adhere to the end. This drop may be then con- veyed to and spread over the floor of the cavity. This will prevent contact of the cement with the most sensitive dentin and lessen the possibility of deleterious action on the pulp. Where it is possible to apply the rubber dam and excavate thoroughly the same excellent result with cement may be expected as when it is used in permanent teeth, but often it is not possible to operate as thoroughly. By applying melted paraffin to the cement,^ the rubber dam may be removed sooner than otherwise, and the cement will be protected from moisture by the coating of paraffin. As paraffin is insoluble in any agent that can attack it in the mouth, the more it is absorbed by the cement the longer it will protect it from everything but wear ; therefore, do not be content to merely flow the melted paraffin over the cement, but hold a heated instrument in contact with the filling and keep the paraffin melted until all that is possible is absorbed. If an approximal filling has been inserted pass a very thin heated spatula between the cement filling and the adjoining tooth to make sure that the paraffin covers it to its cervical margin. When the rubber dam cannot be applied, cement may still be used with success if the cavity can be kept dry w^th napkins or rolls of cotton or spunk until it is inserted and quickly covered with melted paraffin. 554 MANAGEMENT OF THE DECIDUOUS TEETH. Deep cavities may be advantageously lined with cement and protected with paraffin till the cement is hard, when the paraffin may be removed and gutta-percha or amalgam inserted. Cavities in Incisors. — Decay in deciduous incisors is much more rare than in the other teeth, and they are lost so early in child life that it is seldom necessary to fill them. Zinc phosphate cement is the best filling material for these teeth, because they are so small that it is very difficult to shape the cavities properly for retaining other materials. If it is found that cement disintegrates rapidly in approximal cavities, an attempt should be made to shape them so as to retain gutta-percha. The first filling of cement may have removed the sensitiveness suf- ficiently to allow deeper excavating at a subsequent sitting, or there may have been a deposit of secondary dentin, thus removing the pulp from danger of exposure in properly shaping the cavity. Amalgam. — "While amalgam is a valual^le filling material, its use necessitates much greater care in the preparation of cavities than is necessary with gutta-percha or cement, for it neither spreads under mastication like the former nor does it adhere to the walls of a cavity like the latter. The spreading of gutta-percha will stop a leak that would be fatal to an amalgam filling, and cement will adhere in a cav- ity from which amalgam would be easily dislodged. Amalgam should be used when the decay can be thoroughly excava- ted and the cavity prepared with strong smooth edges, and good under- cuts or retaining grooves. As amalgam is a better conductor of thermal impulses than either of the materials before mentioned it will not be tolerated so near the pulp, hence deep cavities must be lined with either gutta-percha or zinc phosphate. The large size of the pulp of deciduous teeth — greater in proportion than that of the permanent teeth — must not be forgotten in exca- vating, and often it is impossible to make suitable retaining grooves for amalgam Avithout cutting dangerously near the pulp, especially in ap- proximal cavities. The preparation of occlusal cavities is comparatively simple, as the enamel may be easily cut away so as to make firm edges, slightly bevelled, and to allow thorough excavation of softened dentin. The burring engine can be used to greater advantage with children than many would suppose. The Avhirring noise often distracts their attention from a slight ])ain they might otherwise notice, and the assur- ance that the work can be done more quickly is a great encouragement. In preparing approximal cavities fi)r amalgam a free opening should be made in the occlusal surface and given a dovetail shape, extending farther upon the occlusal surface in proportion to the size of the cavity than in permanent teeth, because more reliance must be placed on it for FILLING MATERIALS. 555 retention than upon lateral grooves, for there is not much depth of dentin in which to make them. The cervical border of the cavity must be smooth and the floor at right angles to the long axis of the tooth. The lateral walls must be cut smooth and bevelled, and may be slightly grooved. If the cavity extends below the margin of the gum the latter should be crowded away with a temporary stopping or by packing a tightly rolled pledget of cotton between the teeth and relying on its swelling. While the application of a rubber dam is not as essential as in using cement, it is a great aclvantaare, Prepared cavity showms? ^ ' • /- 1 • bevelling of enamel for it renders the proper preparation of the cavity edges, a,a, and square more certain, but it need not be applied till the base for fining, s. cavity is nearly prepared. Its use is more often necessarv with the lower teeth than with the upper. Amalgam should not be mixed too dry, but should be plastic enough to be packed easily without crumbling. In occlusal cavities introduce a piece half as large as the cavity, and with a small ball burnisher spread it over the floor of the cavity toward the walls. Introduce other smaller pieces and proceed as before until the cavity is nearly full. Excess of mercury is thus forced to the edges of the cavity, whence it can be brushed away with cotton or bibulous paper. The last pieces of amalgam should be " wafered," as recommended by Prof. J. Foster Flagg — that is, squeezed in chamois skin with large flat-nosed pliers till as much mercury as possible is pressed out (see Fig. 221). This leaves the amalgam in a thin, brittle wafer, too hard for ordinary use. Break it up in pieces half the diameter of the cavity. Press one of these in the middle of the nearly completed filling. It will readily absorb the excess of mercury that has been worked to the surface, and can be spread toward the margins with a round burnisher. Other pieces can be burnished on till the filling is quite hard. In filling approximal cavities the same plan may be follovv'ed if a matrix of thin steel or German silver be used. In lieu of the matrix a very thin spatula may be held between the teeth. Whenever possible, fillings in deciduous molars should be contoured to avoid the crowding of food between the teeth and also to prevent the first permanent molar from crowding them together and thus taking up room which will be needed by the bicuspids. The child should be cautioned against masticating too soon upon approximal fillings, though no caution is needed in case of occlusal fill- ings hardened by the " wafering " process. Tin and gold are excluded from the list of desirable filling materials for temporary teeth, not because they are not good filling materials but 556 MANAGEMENT OF THE DECIDUOUS TEETH. because the circumstances are such that they cannot be used to advan- tage. Though a small gold filling may be inserted in a few minutes in an occlusal cavity, the insertion of a large gold filling would be inflict- ing a needless cruelty on a child on account of the length of time it must be held in one position. As the insertion of a tin filling is nearly if not quite as difficult and tedious an operation, it is open to the same objections. Exposed Pulps. On account of the difficulty of properly capping an exposed pulp in a deciduous tooth, the operation should seldom be attempted. It is better to devitalize the pulp and remove it. The writer has found the following formula ^ an excellent one : I^. Acidi arseniosi, Morphise acetatis, Pulv. opii, da. pars. ceq. Creosoti q. s. to make paste. Whv opium and acetate of morphia should both be used in the same prescription is lu^t clear, as their properties are so nearly the same, but the paste has been satisfactory in devitalizing pulps with no pain, or with a minimum amount. Other fornudas may be equally satisfactory. In occlusal cavities its application is sim])le. Excavate the softened dentin as thoroughly as possible without inflicting pain, using spoon- shaped excavators to prevent puncturing the pulp. If the excavation can be carried far enough to apply the paste directly to the pulp its action will be more rapid. Dry the cavity, apply a small amount, not larger than half a pinhead in size, with a small probe and cover it with a pellet of cotton, or place in the cavity a small pellet of cotton one side of which has been touched to the paste. Add enough pellets of dry cotton to fill the cavity, then apply a drop of sandarac varnish, suf- ficient to saturate at least half the depth of cotton. This is a better plan than dipping the pellets in the varnish before inserting, because an excess of the latter is apt to come in contact with the pulp and cause ])ain, or, penetrating between the paste and the pulp, may render the former inoperative. Temporary stoppings such as Gilbert's, AVhite's, or Fowler's are excellent for sealing the cavity, but take a little more time than cotton and varnish. Such temporary sto})ping should be well softened by heat to prevent pressure on the pulp in its insertion. A good plan is to warm the end of the long stick of sto])})ing and press it into the cavity, using the remainder of the stick as a handle, then remove the surplus and smooth with a warm instrument. ^ Used by Dr. E. X. Clarke iu the "fifties." FILLING PULP CANALS. 557 In approximal cavities extending near or under the margin, the gmn should be protected, before applying the paste, as follows : Make, by rolling between the fingers, a cylinder of cotton as long as the width of the tooth and about the size of the lead of a pencil. Saturate it with sandarac varnish and pack it between the teeth upon the gum, extending part of it below the edge of the cavity, thus sealing this portion of the cavity and reducing it nearly to the form of an occlusal cavity. Paste applied in an approximal cavity so protected cannot flow upon the gum unless too great a quantity has been used. The paste should be applied and sealed as in an occlusal cavity. " Devitalizing fiber " is very satisfactory and may be used with less ■fear of its affecting the gum tissue. The paste may be allowed to remain in the cavity for from twelve to forty-eight hours. The possibility of the dressing being dislodged, so as to allow the paste to come in contact with the gum tissue, should warn one to have the patient return much sooner than when the case is an occlusal cavity from which it is impossible for the paste to escape. Much has been said about the danger of application of arsenic in deciduous teeth when the roots are undergoing resorption, but the writer has never seen any bad effects from such use ; still it must be admitted that the ratio of danger varies Avith the degree of resorption of the root. "An examination of Prof. Peirce's diagram (Fig. 497) will show the average amount of resorption at different ages, and enable one to discriminate. The writer believes that the sensitiveness of a deciduous pulp varies inversely with the amount of resorption of the root, and that devitalization is called for in very fcAV cases in which there is danger of deleterious action. Prof. L. L. Dunbar advises the use of aqua ammonia for devitaliz- ing the pulp of a temporary tooth, by applying it on a pledget of cotton in the cavity, one or two applications being sufficient in most cases. This plan is not open to the objections urged against the use of arsenous oxid. When the pulp is devitalized, open the cavity freely into the pulp chamber and apply on cotton a solution of tannic acid in glycerol. Leave this about a week, by which time the pulp tissue will have be- come so hardened by the tannin that it may be removed much more readily than without such treatment. Pilling Pulp Canals. In the pulp canals apply iodoform paste made by mixing iodoform and glycerol to such a consistence that it can be readily applied on a probe. Fill the pulp chamber with " temporary stopping " or gutta-percha. 558 MANAGEMENT OF THE DECIDUOUS TEETH. and the cavity with cement, gutta-percha, or amalgam according to indications. If the tooth be very frail, fill the cavity with cement, because, owing to its adhesive properties, it strengthens the tooth. If the cavity be ai)proximal and it is desirable to wedge the teeth apart, use pink gutta- percha. If the walls be strong and some time will elapse before the natural exfoliation of the tooth will occur, fill with amalgam. If absorption of the roots occurs, the iodoform in the canals will not interfere. Salol, which was advocated as a root filling for permanent teeth by Dr. A. E. Mascort ' of Paris, France, is well adapted also for filling the canals of deciduous teeth. " It is a white crystalline powder, insoluble in water and glycerol, but soluble in alcohol, ether, chloroform, etc. ; fuses at 40° C. but crystallizes quickly again." Melted together, salol and aristol, salol and iodoform, or salol and paraffin, become liquid like salol alone. After a pulp canal is thoroughly dried the salol may be fused on a small spatula and carried to the canal, into which it will be taken by capillary attraction or a broach may be heated and inserted in the salol. A small quantity will adhere like a drop of liquid and may thus be carried to the canal. The heated broach may be again introduced in the canal to ensure thorough application. Dr. Mascort uses the hypodermic syringe with a small needle for introducing into the canals. It will crystallize in a very short time, making a solid fill- ing. Though the writer has not had much experience with salol as a root filling, he is so far well pleased with the result. (See Chapter XV., p. 327.) Alveolar Abscess. The treatment should be the same as with the permanent teeth, that is, removal of the cause — which is, almost invariably, a decomposed pulp. Even with a decomposed pulp an abscess seldom occurs if there be any opening from the cavity of decay to the pulp chamber, unless such opening has become stopped by some foreign substance. Make a free opening into the pulp chamber and with a syringe wash out as much of the contents as possible. Dry the chamber and with a " minim " syringe (see Chapter XV., Fig. 348), or drop tube, apply hydrogen dioxid. AVhile capillary attraction will carry this into a dry canal, the application of a nerve broach, preferably platino- iridium, will serve to mix it thoroughly with the contents of other canals, and increase its efficiency. If a fistulous opening has formed through the outer alveolar plate but not through the gum, an opening should be made through the latter ' Dental Cosriioii, 1894, p. 352. PROPHYLACTIC TREATMENT. 559 with a sharp lancet about five minutes after the application of 4 per cent, cocain hydrochlorid solution on a wad of cotton. If hydrogen dioxid can be forced from the pulp chamber through the root canals and fistulous opening, the accumulated pus will be thoroughly evacuated and the cure hastened. As a rule, however, the abscess disappears after the cause is removed, that is, the putrescent or decomposed contents of the pulp chamber and canals. After drying the pulp chamber and canals, apply iodoform paste therein and seal the cavity for a few days with temporary stopping. When the inflammation of the pericementum has disappeared the pulp chamber and canals may be filled as before directed. In many cases the inflammation of the pericementum will be so great, or in popular expression the tooth so " sore " to the touch, when the case is presented that at the first sitting nothing more can be done than to make an opening into the pulp chamber to allow the escape of pus or gases of decomposition. By this means the pain will be re- lieved and the rest of the manipulation and treatment may be left till the inflammation has subsided. Prophylactic Treatment. This lies more in the hands of the parent than of the practitioner^ but should be strongly urged by the latter upon the former. The nurse or parent should begin early to clean the child's teeth by means of a cloth wrapped around the finger. If the teeth cannot be kept clean in this manner a small brush should be used, especially after eruption of the molars. Floss silk should be used daily between the teeth. One end of the silk should be held in each hand in such a manner as to pass over the end of each index finger and be made taut between them. This taut part can be pressed down between the teeth and passed up and down against the approximal surface of each tooth, then one end of the thread should be released from one hand and pulled through the interdental space with the other. This will drag out any particles of food that may be there, and is much better than the toothpick for the purpose. If particles of meat or other food have lodged so firmly that the plain waxed silk will not dislodge them, tie a single knot in the thread and pull that through. This cleansing with the cloth, brush, and silk should be done before the child retires at night, for that is the "■ period of decay." The parts are at rest longer than at any other time, and the fluids of the mouth are not kept in circulation between the teeth by means of the tongue, lips, and cheeks. Theoretically the teeth should be thus thoroughly cleaned after each meal, but " satiety breeds disgust," and it is not best to insist on more than will probably be accomplished. 560 MANAGEMENT OF THE DECIDUOUS TEETH. Children will soon learn to nse the brush and floss silk themselves, and finding tlie mouth much more comfortable when "clean" they will endeavor to keep it so. Many a child has been denied candy for years from the belief that " sweets decay the teeth," but parents may be as- sured that no harm will be done if the " sweet " is not allowed to remain between and around the teeth till it becomes acid, and that may be prevented by cleansing the teeth after the candy or sugar is eaten. A child may be taught cleanliness in this manner who would be only taught rebellion by the repeated denial of sweets, the reason of which he cannot understand. Prophylactic mouth-washes should be used — such as listeriue diluted to a 10 per cent, solution. CHAPTER XXII. ORTHODONTIA EXCLUSIVELY AS AN OPERATIVE PROCEDURE. By Claek L. Goddaed, A. M., D. D. S. The Normal Arch. — As the study of physiology is necessary before the study of pathology, so is a study of the normal arrangement of the teeth necessary before the treatment of their irregularities should be undertaken. The ideal facial profile is shown in Fig. 500. The face from the Fig. 500. The facial profile. hair to the chin measures three-fourths of the whole height of the head. The forehead to the root of the nose measures one-fourth, the nose one- fourth and the mouth and chin one-fourth. The distance vertically from the root of the nose to its lower border is equal to the distance from this point to the bottom of the chin. Of this latter distance one- half is occupied by the lips and one-half by the chin. The nose, then, equals in length the lips and chin. 36 561 562 ORTHODONTIA AS AN OPERATIVE PROCEDURE. The upper dental arch is shown in Fig. 501. The six anterior teeth are arranged in the segment of a circle. The bicuspids and molars Fig. 501. Normal upper flental arch. form almost straight diverging lines from the cuspids, though the posi- tion of the third molar is somewhat outside of that line. The normal occlusion of the teeth is shown in Fig;. 502. The six upper anterior teeth close over the six lower from a third to a half Fk). 502. Normal occlusion. of the length of the latter. The lower second bicuspid occludes between the cusps of the two upper bicuspids ; this is a point easily remem- bered. Each bicuspid and molar of each jaw, excepting the upi)er third molar, is antagonized by two of the teeth of the opposite jaw. THE NORMAL ARCH. 563 Fig. 503. The six anterior upper teeth. The buccal cusps of the lower teeth close between the buccal and lingual of the upper, and the lingual cusps of the upper close between the lingual and buccal cusps of the lower. As the lower jaw moves laterally during mastication the cusps of the bicuspids and molars grind upon each other, while the six anterior teeth, overlapping but not touching, pass by each other and escape wear. In order to touch the cutting edges of the upper and lower incisors upon each other the lower jaw is protruded, and at such a time the masticating teeth do not occlude. In examining the upper six an- terior teeth from the labial aspect (Fig. 503) it will be seen that they touch each other at one point only, about one-fourth of the distance from the cutting edge to the gum, and that the long axes of the teeth are not parallel but the crowns slant toward the median line. Of the six upper anterior teeth the central incisors are the longest, the laterals next, and the cuspids shortest, though popularly the cuspid is thought to be the longest tooth because of its prominence and the length of its cusps. It will be noticed that the gum line is higher on the cuspid, thus adding to its apparent length. A line connecting the cutting edges and cusps of half the upper teeth forms a double curve, highest at the third molar and lowest at the central incisor, the line of beauty, while such a line on the lower teeth forms but one curve, highest at its ends. While the aim of the student of orthodontia will be to correct all irregularities, and reduce the abnormal to the normal, it will be possible in many cases to do this only in degree. The normal may always be approached, but not always attained. Order of Eruption of Permanent Teeth} 1 . Central Incisors — from 6th to 8th year. 2. Lateral " u 7th" 9th 3. Lower Cuspids ii 8th " 10th 4. First Bicuspids a 9th " 10th 5. Second " (C 10th " 12th 6. Upper Cuspids u nth " 12th 7. First Molars iC 5th " 6th 8. Second " a 12th " 14th 9. Third (( 17th " 25th Farrar, Treatment of Irregularities of the Teeth, vol. i. p. 483. 564 ORTHODONTIA AS AN OPERATIVE PROCEDURE. While most tables place the eruption of all the cuspids after that of the bicuspids, it will be noticed that, in this, the lower cuspid pre- cedes and the upper cuspid follows both bicuspids. The lateral incisor fails to erupt more often than any tooth except the third molar. It also erupts out of line more often than any tooth except the cuspid. The difference in order of eruption of the upper and lower cuspids has an effect upon the position of those teeth. The upper cuspid erupts out of line more often than the lower, while irregularity of the lower ljicus})i(ls is more frequent than of the upper. In each case, being the last of the suecessional teeth to erupt, there is often insufficient room to enable them to assume their normal positions. Etiology of Dental Irregularities. The causes of irregularities of the teeth may be divided into heredi- tary and acquired. As children inherit other peculiarities of structure from father, mother, grandparent, or even from more remote ancestors, so may irreg- ularities of the teeth be inherited. The causes are operative before the birth of the child. Hereditary causes may be divided into two : {; plan has been successfully applied by the writer for elevating bicuspids and molars which do not occlude. Bands with hooks are attached to both upper and lower teeth and a rubber band stretched from each upper hook to a corresponding lower ' Pacijic Coast Dentist, vol. i. p. 14. PARTIAL ERUPTION. 597 one, or the place of either upper or lower band is supplied by a liga- ture. The teeth, being drawn out of their sockets toward each other, will soon meet and adapt their occlusal surfaces to each other. This Fig. 578. ' Restoration of occlusion. adaptation may be assisted by grinding or re-shaping any cusps that may be an obstruction. The following case will serve to illustrate reciprocal movement : The central incisors of a patient about twenty years of age were par- tially denuded of enamel for about ^ of an inch from the cutting edge. Fig. 579. Labial bow for elevating centrals and depressing cuspids. The lateral incisors had the same defect at the cutting edge only. It was thought best to elevate the central incisors, and grind oif the por- tion denuded of enamel. Bands were fitted to the centrals (Fig. 579) with hooks on their labial surfaces pointing upward, also on the cuspids Fig. 580. Labial bow for retention. with hooks pointing downward, and on the second bicuspids with tubes on their buccal surfaces. A wire bow was extended from the tube on the left bicuspid to the tube on the right, and caught under the hooks 598 ORTHODONTIA AS AN OPERATIVE PROCEDURE. on the cuspids. Slender rubber bands wei'e then stretched from the wire over the hooks on the centrals, and soon elevated them sufficiently to grind off the denuded portion. The same ajipliance was used as a retainer by bending the bow wire upward slightly and hooking it over the hooks on the incisors. The elevation of a broken upper incisor is sometimes interfered with by occlusion of the lower incisors on the slanting lingual surface Fig. 581. Flattening lower arch with laljial liow. so that it is necessary to shorten the lower incisors by grinding. In some cases it is warrantable to grind away the upper incisor on the lingual surface, where too much grinding of the lower teeth would mar their appearance. In the case just described it was necessary to press the lower incisors back by flattening the arch as shown in Fig. 581. Fig. 582. Forcible eruption of cuspids. The following case of forcible eruption may be instructive : Miss R. W., aged eighteen, presented herself with the point of the upper left cuspid erupting behind the lateral incisor while the deciduous TOOTH SHAPING. 599 cuspid was still in place. The cusp had penetrated the gum about a year before, but had during that time made no progress in eruption. The writer decided to cause the tooth to erupt forcibly, by means of a coiled spring as suggested by Dr. Talbot. As the deciduous cuspid was large and firm and but slightly decayed, it was thought best to let it remain in place till the permanent tooth was erupted far enough to see if it were well formed. By depressing the gum slightly a hole was Showing result of operation. drilled in the enamel in the lingual surface of the tooth. In this hole was inserted one end of a coiled spring, which was attached to a plate, as shown in Fig. 582, which shows the cusp emerging from the* gum. The tooth was soon erupted to its normal length, when the deciduous cuspid was extracted. By means of a rubber band from a labial bow, the ends of which rested in tubes attached to bands on right and left bicuspids, the tooth was readily brought into line as shown in Fig. 583. Fig. 584. Fig. 585. A band-and-bar retainer (Fig. 536) was applied to keep the tooth in place till it became firm. Tooth Shaping. — The operation of grinding has been referred to in the shortening of an extruded tooth, and also for re-shaping a tooth from which a corner has been broken after haviug first elevated the tooth. (See Fig. 574.) It may be advantageously employed for re- 600 ORTHODONTIA AS AN OPERATIVE PROCEDURE. shaping teeth which have been left longer than the contiguons ones by the wearing away of the latter, as shown in Figs. 584-587, suggested by Dr. AV. S. How.' In many instances upper incisors are worn away on their lingual surfaces, leaving thin edges of labial enamel Avhich are easily broken away irregularly. (See Fig. 588.) These broken edges may be re- moved and the teeth improved very much in appearance by grinding. The cusps of bicuspids and molars sometimes interfere with the Fig. 586. Fig. 587. desired movement of an antagonizing tooth and may be reduced by grinding so as to present no obstruction. Lower cuspids Avhich prevent upper cuspids or lateral incisors from moving into their proper position may have the apex of the cusp ground away, and in some cases even a portion of the labial enamel may be re- moved to advantage. An incisor which inclines toward the contiguous tootli so much as to present one angle lower than the other may have this corner ground away so as to present the cutting edge in line with tiie other teeth. Fig. 589 shows Fig. 588. Fig. 580. Worn or broken teeth (Farrar). Showing thickness of enamel (Farrar). how much of the enamel of a tooth may be removed in various cases without exposing the dentin. " Truing up " is a term apjjlied by Dr. Farrar to the process of re- moving overlap])ing portions of teeth so that they will present a normal appearance. (See Figs. 590 and 591.) Much di-scomfort may be prevented if the corundum Avheel be held as in Fig. 592, as the tooth is supported by the contiguous ones and less jar is felt. Fine-grained corundum wheels should be used and the ' Dental Cosmos, vol. xxviii. p. 741. TOOTH SHAPING. 601 surface should afterward be thoroughly polished by means of cuttle fish disks, or with felt or wooden wheels carrying polishing powder. If the grinding should not be carried so far as to be painful a slight sensi- tiveness may be felt for a few days, when the operation may be resumed. Cataphoresis has been successfully applied by the writer for allaying sensitiveness. If a tooth needs to be reduced considerably in length Fig. 590. Truing up (Farrar). the dentin may be exposed on the cutting edge with impunity, as it is kept free from decay by the tongue and lips. The enamel may be beveled on one or both surfaces to reduce the thickness of the cutting edge. Approximal Surfaces. — In rare instances the removal of a slight amount of enamel from approximal surfaces of incisors or cuspids is permissible for the purpose of making room. The operation should be confined to teeth easily kept clean, to teeth unusually rounded on their ap- Fig. 592. proximal surfaces, and they should be reduced only to a normal contour and Fig. 591. Truing up (Farrar). Position of corundum wheel (Farrar). be thoroughly polished. Flat approximal surfaces should never be produced, as caries is almost sure to be the result. The patient should be warned to use extra care with the brush and floss silk. Disks or strips of sandpaper, emery, or garnet may be used for 602 ORTHODONTIA AS AN OPERATIVE PROCEDURE. removing a portion of enamel, after Avliich cuttlefish disks or strips should be used for polishing. Class 6. Two or More Teeth in Any or All of the Five Mal- positions. — One of the oldest and simplest appliances, which requires very little skill in its construction, is shown in Fig. 593. It can be Fig. 593. Labial bow and plate. (From Kingsley.) used with either upper or lower jaw, and consists of a vulcanite plate fitted against the lingual surfaces of the teeth. Imbedded in this plate are the ends of a wire which extends through such gaps, when the jaws are closed, as are most favorable, and around the buccal and lingual surfaces of the teeth. The cut shows the manner of attaching rubber Fig. 594. Plate and wire bow for moving teeth in all positions. bands by which teeth may be drawn forward. The wire should l)e from jlg to 1^ of an inch in advance of the teeth to be moved, and may l)e elongated from time to time by hammering the sides on the beak of an anvil. By attaching rubber bands to the plate, teeth may be drawn into the arch, as shown in Fig. 594, B. By stretching rubber bands SEVERAL TEETH IN MALPOSITION. 603 either from the wire or plate to hooks such as shown in Fig. 594, A, teeth may be rotated. For such purpose it is in some cases best to solder hooks on both labial and lingual surfaces of a band, and thus apply force from wire and plate at the same time. By attaching a rubber band at that part of the wire which emerges from the plate (Fig. 594), a tooth may be drawn backward along the ridge. If the wire extends near to the cutting edge an incisor may be extruded by ligating a rubber band at the neck and extending it to the wire. In some cases it is necessary to ligate the plate firmly to tem- porary molars or bicuspids. This has a wider range of use than any other single apj^liance, for wdth it teeth may be moved outward or in- ward, rotated or elongated, or the arch may be spread. (See Fig. 594, A, B, C, D.) It is, however, much less stable and much more un- cleanly than are many other appliances attached directly to the teeth. Fig. 595. Labial and lingual bows for teeth in all positions. The same movements may be made with the bows shown in Fig. 595. Bands are cemented on one or two teeth on each side of the mouth, pre- ferably two for stability, in which case the bands should be soldered together. Tubes are soldered on both buccal and lingual sides of the bands. In these tubes are inserted wire bows, screw-cut on the ends and supplied with nuts. One bow extends around the labial and the other around the lingual surfaces of the teeth. To these wire bows, rubber bands may be attached to move teeth in all directions, for instance at B, for moving a lateral incisor into the arch ; at A, for rotating a central incisor ; at D, for drawing a cuspid backward along the ridge ; and at C, for drawing a lateral forward. This last rubber band should not be applied till after the cuspid has been moved out of the way. The bows may be used independently as follows : the labial bow may 604 ORTHODOyTIA AS AN OPERATIVE PROCEDURE. be used for moving incisors backward by placing the nuts behind the tubes (Fig. 545), or for moving incisors forward by placing the nuts in front of the tubes, and ligating the wire to the incisors, or putting it Fig. 596. Labial and lingual bow. under hooks soldered to bands on the incisors. It may be used for the attachment of rubber bands for drawing incisors forward (Fig. 605), in which case the wire may be bent in a bayonet shape at the ends, or the rear ends of the tubes mav be closed. Ftg. 597. Lingual bow fur moving incisors fonvard (Matteson). The lingual bow may be used for moving any or all four incisors forward by placing the nuts in front of the tubes. The anterior portion of the wire may rest in notches in the bands on the incisors (Fig. 597), RETENTION OF TEETH MOVED FORWARD. 605 Fig. 598. or a short piece of wire may be soldered to the front of the bow and inserted between the centrals above the points and their mesial surfaces. Other short wires may be soldered on so as to engage the distal borders of the laterals to prevent their being moved sideways. (See Fig. 596, B.) This appliance has as wide a range of application as that shown in Fig. 594, and is much more stable. Fig. 598 shows the writer's modi- fication of the Coffin spring plate for moving incisors forward. A wire should be imbedded in the anterior portion of the plate to project between the centrals to prevent sliding on the inclined surfaces. Retention of Teeth Moved FoRWAED. — This has often been ac- complished by a simple vulcanite plate retained by atmospheric pressure and impinging on the lingual surfaces of all the teeth involved. Objections to this are that it is easily displaced, even sometimes by the incisors on whose inclined surfaces it impinges ; retention of fermenting debris or secretions in contact with the teeth, and liability to be left out by the carelessness of the patient when the teeth return partly to their malpositions. Fig. 599 shows a retaining appliance of Prof. Angle's, consisting of a wire bent so as to rest in Writer's modiflcation of Coffin split vul- canite plate. Fig. 599. E.H.A. Angle's retainer. contact with the lingual surfaces of the teeth involved, soldered to bands on the cuspids, and the ends cemented in pits drilled in the molars. It may be used in the lower arch as well as the upper. 606 ORTHODONTIA AS AN OPERATIVE PROCEDURE. In many cases the anterior portion only of this appliance may be used. Several teeth moved in different positions may be retained by bands soldered together and cemented in place. (See Fig. 600.) Lower Incisors Crowded in All Positions. — This is a very common irregularity owing to the teeth being too large for the incisor space, or the space being encroached upon by the cuspids. The simplest way to make room is to extract liand. soidLicd together ^^^^^ ^^ ^^iQ crowdcd tccth, the one forthest out of for retention. position or that rotated the most. The four teeth are so nearly of the same size that few can tell without counting whether there are three or four between the cuspids. AVhen room has been made, the remaining teeth may be brought into line by the same means that have been described for upper incisors. The labial bow attached to bands on bicuspids or cuspids will form attachment for rubber bands or ligatures for moving the incisors into position. In some cases it is better to spread the arch as shown in Fig. 609. Owing to the relative positions of the alveoli of the central incisor and cuspid to that of the lateral incisor there is always a tendency for the lateral incisor to erupt within the arch of the adjoining teeth. Class 7. Prominent Cuspids and Depressed Laterals. — Etiology. — This common form of irregularity may be — (a) Constitutional — due to lack of development of the intermaxillary bone. (6) Inherited — large teeth and small jaws, (c) Acquired — from premature extraction of the deciduous cuspids, {d) From premature extraction of second deciduous molar and crowding forward of first jiermanent molar, leav- ing less than the normal room for bicuspids and cuspid. (Figs. 601 and 603 show this irregularity.) Treatment. — To make room for ])roper arrangement of the teeth in this class, it is necessary either to expand the arch or to extract one or more teeth. Unless the arch will admit of expansion to advantage, extraction is better. If expansion would make the arch too large, or the anterior teeth too prominent, extract. If the .superior maxilla itself is so narrow that expansion would make the bicuspids and molars .slant outward too much, extract. If caries is prevalent, extract. In favor of expansion, it may be said that if the full number of teeth are retained, the pain of extraction is obviated, and the narrow arch is widened to correspond with the other features. PROMINENT CUSPIDS AND DEPRESSED LATERALS. 607 In favor of extraction : Room is gained more easily ; the treatment is simplified, as there are fewer teeth to be moved ; the teeth are retained in their new positions more easily, because if the full number of teeth Fig. 601. Case treated by extraction only. be retained the same cause that produced the irregularity may tend to reproduce it, while if room be made by extraction the action of the lips and tongue tends to move the teeth into the normal arch. Fig. 602. Showing the same denture as Fig. 601 a few months after extraction. In many cases no other treatment than extraction is necessary, as shown in Figs. 601 and 602. Having decided upon extraction in any case under consideration, the choice lies between a lateral incisor and some tooth posterior to the cuspid. The cuspid should never be extracted, as on account of, its 608 ORTHODONTIA AS AN OPERATIVE PROCEDURE. long root and prominent position its loss causes a depression of tlio corners of the lip and wing of the nose which can never be remedied. The choice between a lateral incisor and some tooth posterior to the cuspid depends on the position of the apex of the root of the cuspid, and also of the lateral. If the apex of the root of the cuspid is so situated that the crown slants away from the median line, or \\\\\ do so after being moved into its normal position, the extraction of one or botli laterals may be admissible. If a lateral is unusually tar l^ack of the normal line and the apex of the root also, when the tootli is moved forward till the cutting edge is in line with the centrals the neck of the tooth will be back of its proper position — that is, the tooth will have an unnatural slant forward. This is not of as much importance as the position of the apices of the roots of the cuspids, but it should be taken into consideration in connection with the other factors. One method of moving incisor roots is shown in Figs. 677-G81. In verv rare cases a central incisor may be extracted to gain room — that is, if very badly decayed, if an incurable abscess exist, or if only the root remain and cannot be crowned to advantage. In the lower arch an incisor may be extracted to advantage in many cases ; the four teeth are so nearly alike in appearance that the absence of one is not noticed. If in a given case it seems best to extract some tooth posterior to the cuspid, the choice will be between a bicuspid and the first molar. If the bicuspids and first molar be equally sound, extract the first l)icuspid. That will leave tAvo teeth for anchorage in retracting a cuspid (Fig. 603, left), or, if the second molar be erupted far enough, Fig. 603. Writer's modification of Guilford's appliance. three teeth may be utilized. Very secure anchorage is necessary in this instance, for the cuspid is the most difficult tooth to move, and oftentimes the two anchor teeth will move more readily than the cuspid. In some cases tlie cuspid needs to be moved back but little ; then tlie PROMINENT CUSPIDS AND DEPRESSED LATERALS. 609 second bicuspid only need be used for anchorage (Fig. 603, right), and the two teeth moved toward each other to fill up the space. The molar will follow, owing to the tendency of the posterior teeth to move forward. If, however, the second bicuspid or first molar be so defect- ive as not to be easily preserved by filling, the defective tooth should be extracted. This, however, will complicate the case, as there are more teeth to be moved and fewer for anchorage. In using the appliance shown in Fig. 603 rubber bands are gener- ally utilized for applying force, but twisted ligatures of silk, linen,, or wire may be used, as shown in Fig. 604, in which case there is less liability to pericemental in- flammation. Fig. 604. Fig. 605. Twisted ligatures of silk, linen, or wire. Labial bow added to retracting appliance. After the cuspid is moved into position, it may be retained by substi- tuting fine platinum or silver suture wire for the rubber bands. The buccal tubes, which served as hooks in the first case (see Fig. 603), may now be utilized for inserting the ends of a wire bow which passes in front of the incisors. Rubber bands or twisted ligatures from ^^^- ^^^' this bow will draw the lateral incisors forward. (See Fig. 605.) An inner bow may be placed in the lingual tubes and utilized for Fig. 606. Stationary anchorage (Angle). Angle's drag-screw. drawing central incisors backward, or rotating them, as is often neces- sary in such cases. ;^9 610 ORTHODONTIA AS AN OPERATIVE PROCEDURE. If either cuspid needs rotating, a rubber band will be needed on one side of the tooth only, and the hook may be so placed on the band that the tooth will be rotated while it is being drawn back. Prof. Angle advises the use of the drag-screw for retracting cuspids, as shown in Fig. 606, By soldering a long tube to two bands which are cemented to two teeth, and extending the drag-screw through this tube, he reduces to a minimum the possibility of the teeth tilting. This appliance is very effective. The position in which the hook is attached to the cuspid band will depend on whether it should be rotated or not in retraction. (See Fig. 607.) After the cuspids are moved to their new position the same appliance mav remain as a retainer. It will be found that a cuspid moved into its proper place, when room has been made by extraction, will need retention less than any other tooth. Greater anchorage may be obtained Ijy a plate such as shown in Fig. 608, for it impinges upon the anterior alveolar ridge and Fig. 608. Plate for retraction. incisors as well as upon the posterior teeth. Its use is especially advantageous when a second bicuspid or first molar has been extracted, for then one or two teeth must be moved before the cuspid. The cut will explain the method of applying force to the teeth to be moved. The wire or clasp should encircle the posterior tooth, for greater anchorage. Fig. 609 shows a reciprocal appliance for these cases by Dr. R. L. Taylor of San Francisco. The laterals are drawn forward and the cuspids ])ushed back and elevated at the same time, after the first bicuspids had been extracted to make room. Fig. 610 shows a valuable appliance by Prof. Guilford for moving four incisors fi)rward, and bicuspids back, to make room for cuspids. He thus descrilies it : " Magill bands were made to fit the laterals, with gold spurs extending along the palatal surface of the centrals to ensure PROMINENT CUSPIDS AND DEPRESSED LATERALS. 611 uniform movement of the four incisors. Palatal bands were also at- tached to the first bicuspids. All of these bands were reinforced with an additional piece of platinum soldered to the portion next to the space. Through these reinforcements, at about the centre of the tooth, Fig. 609. Dr. R. L. Taylor's reciprocal appliance. holes were drilled entirely through the bands. Piano wire was next bent into the form of small U-shaped springs, with the ends at right angles, similar to Dr. Talbot's plan but without the coil. Grasping these near the neck with a pair of narrow-beaked right-angle forceps. Fig. 610. Guilford's appliance for increasing space. transversely grooved near the points to seize the wire, the springs were placed in position with their ends resting in the holes in the bands. As from time to time the force of these springs became spent they were removed and their power renewed by enlarging their curves." In case of extraction of first molars, the bicuspids may be moved backward and the incisors forward by Prof. Guilford's appliance. 612 ORTHODONTIA AS AN OPERATIVE PROCEDURE. Fif. 611 shows Prof. Angle's method of reinforcing the anchor teeth by a wire bar extending to the lateral incisor. Fig. 611. Angle's reinforcement. Fig. 612 shows another method of Prof. Angle's for drawing the cuspid in. Fig. 612. Drawing cuspid in. The lower cuspid is the most difficult tooth to move. If the first bicuspid be extracted to make room, the second bicuspid and first molar will in many cases be moved for- ward in an attempt to use them as anchorage in retracting the cuspid either with a screw or elastics. It Fio. 614. Fig. 613. Jackson's appliance for lower arch. Flat tube for piano-wire sprin<. is often necessary to construct an appliance of such a shape that all the other teeth can be used as anchorage. SPREADING THE ARCH. 613 Fig. 613 shows Dr. Jackson's method of retracting the lower cuspid in such cases. The base wire rests against all teeth that it is not desired to move and gives etFective anchorage. Fig. 614, A, shows another method of applying a piano-wire spring by bending a loop on one end and inserting it in a flat tube soldered to . Fig. 615. Author's combination for expansion. a molar band. The spring is thus prevented from turning. The loop may be so bent that the spring may be inserted in the posterior end of the flat tube. Spreading the Arch. — For .spreading the arch an appliance should be firmly fixed upon the teeth and should have suflicient power, Fig. G16. Matteson taps in place of binds m appliance foi expansion. which can be well regulated. For such an appliance the writer has made a combination of Magill bands, Angle's jack-screw, and Talbot's spring, as shown in Fig. 615. While resembling other devices for the same purpose, it has this distinction : The bar connecting the bands on 614 ORTHODONTIA AS AN OPERATIVE PROCEDURE. the lingual surfaces of the teeth is perforated at short intervals by holes in which are fitted the ends of a Talbot spring or an Angle jack- screw. This bar should be stiff, about Xo. 23 B. & S. gauge. The position of the screw or spring may be changed, according to the part which needs the greater expansion. If necessary, two springs or two Fig. 617. . Writer's combination with Angle's jack-screw. jack-screws may be used at the same time. The coiled spring should be bent to conform to the palatal vault, so as to interfere but little with the patient's tongue as does the jack-screw. In case of very short molars and bicuspids it is best to use Matte- son caps in place of bands, as shown in Fig. 616. Fig. 618. Writer's appliance for widening lower arch and moving incisors forward. Fig. 617 shows the use of the jack-screw and Fig. 618 the appliance for the lower arch. In this the Matteson spring is used Avith two coils between which is a straight part which lies near the floor of the mouth. When the arch has been spread the bent wire c, Fig. 615, is sub- THE POINTED OB GOTHIC ARCH. 615 stituted for the spring or jack-screw, for retention. It may lie along the necks of the teeth, and in such position be utilized for attachment of rubber bands for retracting or rotating incisors, as shown in Figs. 549 and 595. The long wire a, b, Fig. 615, is used for moving incisors forward, as shown in Fig. 605. These two wires are the labial and lingual bows previously referred to. Class 8. The Pointed or Gothic Arch (the V-shaped Arch). — Etiology. — The pointed arch (generally miscalled the V-shaped arch) may be due to the presence of teeth too large for the jaw or to the first permanent molar having moved forward from its normal position on account of premature loss of the second deciduous molar. In either case, taking the first molar as a fixed point for the base of the arch on each side, the teeth forward of that point must arrange themselves in a portion of the jaw which is too small for them. The incisors erupt first, the bicuspids next, and the cuspids last. It depends on the manner of approximal contact whether the result is a pointed arch, a constricted arch, or results in Class 7 — " Prominent cuspids and depressed laterals." If all of these teeth erupt in proper alignment, they will touch each other approximally like the stones of an arch ; the second bicuspid not Fig. 619. Pointed arch (V shaped arch). having sufficient room — either from its extra size or because the first molar has taken part of its room — will crowd the first forward, and the cuspid, erupting as a wedge in front of the bicuspids, which are immov- ably fixed against the first molar, will crowd the incisors forward, because they are situated in a thin alveolar process which is easily moved. As the incisors move forward, crowding upon each other, they rotate in their sockets and assume the V shape. ^ ^ See Talbot, 3d ed., chap, xxxii., and Ottolengui, Dental Cosmos, June, 1892. 616 ORTHODONTIA AS AN OPERATIVE PROCEDURE. The teeth may assume a pointed arch from having too much room, either on account of extraction or from being too small for the jaw. When the teeth are deprived of approximal sujiport there is a tendency for the sides of the arch to flatten or move toward the median line. The semi-V of Dr. Talbot's classification is one in which the causes named have operated on one side only of the arch. Fig. 620 shows a semi-V arch due to the last cause mentioned. The V shape assumed by the central incisors may be due to lack of development of the inter- FiG. 621. Fig. 620. Semi-V-shapt'