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LIST OF CONTRIBUTORS. 
 
 BUNTING, RUSSELL W., D.D.Sc. 
 CAPON, WILLIAM A., D.D.S. 
 CONZETT, JOHN V., D.D.Sc. 
 COOLIDGE, EDGAR D., D.D.S. 
 HOPEWELL-SMITH, ARTHUR, Sc.D., M.R.C.S. 
 LYONS, CHALMERS J., D.D.Sc. 
 NOYES, FREDERICK B., B.A., D.D.S. 
 PRINZ, HERMANN, A.M., M.D., D.D.S. 
 THOMA, KURT H., D.M.D. 
 VOLLAND, ROSCOE H., M.D., D.D.S. 
 WARD, MARCUS L., D.D.Sc. 
 
THE 
 
 AMERICAN TEXT-BOOK 
 
 OF 
 
 OPERATIVE DENTISTRY. 
 
 IN CONTRIBUTIONS BY EMINENT AUTHORITIES 
 
 EDITED BY 
 
 MARCUS L. WARD, D.D.Sc. 
 
 PKOFESSOR OF DENTAL METALLURGY AND CROWN AND BRIDGE WORK, AND DEAN OF THE 
 COLLEGE OF DENTAL SURGERY, UNIVERSITY OF MICHIGAN 
 
 FIFTH EDITION, THOROUGHLY REVISED 
 
 ILLUSTRATED WITH 762 ENGRAVINGS AND A COLORED PLATE 
 
 LEA & FEBIGER 
 
 PHILADELPHIA AND NEW YORK 
 1920 
 
&l^^JmI!a^ 
 
 Z^-8l0( 
 
 
 COPYRIGHT 
 
 LEA & FEBIGER 
 1920 
 
\ 
 
 WITH THE CONSENT OF THE CONTRIBUTORS 
 
 THIS VOLUME 
 
 IS DEDICATED TO THOSE WHO HAVE AIDED IN THE DEVELOPMENT OF 
 
 OPERATIVE DENTISTRY 
 
 TO WHOM IT HAS NOT BEEN POSSIBLE TO GIVE CREDIT 
 
PREFACE. 
 
 The demand for a new edition of the American Text-book of Opera- 
 tive Dentistry has necessitated much more than a mere revision of the 
 previous text. The work has been largely rewritten and the fifth 
 edition is therefore practically a new book. Such a radical change has 
 been rendered necessary by the rapid evolution which has taken place 
 throughout the entire domain of the science and art of dentistry since 
 the publication of the previous edition. The accumulation of new 
 data, the investigation of the deeper problems of dental science, and the 
 modification exerted by these factors upon the practice of dentistry 
 have wrought changes that in certain departments are little less than 
 revolutionary. So rapid and far-reaching in their effects are many of 
 the changes which have taken place that the whole subject of operative 
 dentistry has been and still is in a state of flux. 
 
 The mirroring of the progressive movement in operative dentistry 
 will be evident in the plan as well as in the text of this work. The 
 constantly growing demand for preventive dentistry has made it 
 necessary to treat several subjects in a much more extensive manner 
 than has been done in former editions in order that the undergraduate 
 student may more intelligently comprehend preventive dentistry in its 
 relation to all other operative procedures. 
 
 It is fully recognized that the scientific basis of many of the subjects 
 which constitute preventive dentistry in its broadest sense is much 
 more fully elaborated in the present work than would be justifiable in 
 a treatise or text-book devoted exclusively to operative dentistry as an 
 art; but as there appears to be a demand upon the part of students and 
 practitioners for a volume furnishing a comprehensive view of the 
 fundamental principles upon which alone an intelligent and rational 
 practice may be based, the treatment of the subject of operative 
 dentistry in the present work has been extended to include those 
 principles. 
 
 Certain differences of opinion will be occasionally manifest in the 
 work in the treatment of allied subjects by different authors. While 
 such differences are, of course, not desirable, and while qo conflict of 
 opinion will be noticed with respect to established scientific principles, 
 
 (ix) 
 
X PREFACE 
 
 it is manifestly impossible to secure unanimity upon subjects which 
 have not as yet reached a stage of development entitling them to 
 classification among the exact sciences, and which are subject to the 
 variations in methods of procedure of different individuals. For exam- 
 ple, it will be observed that all the contributors to this work have used 
 the nomenclature advocated by Dr. G. V. Black iti describing the teeth 
 and their anatomy except the three who have written chapters who are 
 associated with departments of general and comparative anatomy. 
 The latter have used the words canine, premolar, etc., which appear 
 to some general and comparative anatomists as the logical terms, 
 while the former have adhered to the use of the terms cuspid and bicus- 
 pid, etc., in accordance with more common usage. As dentistry con- 
 tinues to develop as a branch of medicine, it appears possible that the 
 opinion of the anatomist will prevail and some of the terms now 
 generally used by the dental profession to describe the teeth, and 
 which seem to have been useful in the development of operative 
 dentistry, will be displaced by terms more accordant with the funda- 
 mental subjects of general and comparative anatomy. Such differ- 
 ences of opinion are not at present reconcilable, and cannot be, until 
 the bar of professional judgment has decided which school of thought 
 is based upon the better observation and experience. 
 
 The progress in the development of the fundamental principles and 
 technic of correcting mal-occlusion has been so rapid that orthodontia 
 has become a specialty with a scope so broad that it has seemed wise 
 to include in this work only the principles of orthodontia that a general 
 practitioner should know in order to enable him to advise intelligently 
 those who are in his care. In submitting this work to the critical 
 consideration of former contributors to the subject, fellow-teachers 
 and students, it is the desire of the editor to do so with the highest 
 respect for orthodontia as a progressive and preventive measure — his 
 only reason for curtailing the subject in this volume being inability to 
 allow a sufficient space for an appropriate presentation of the subject 
 in its present state of development. 
 
 The progressive movement in operative dentistry is still further 
 reflected in the chapter on roentgen diagnosis. A study of the advances 
 which have taken place in the field of roentgenology reveals, besides 
 important additions to our knowledge, a vastly more important 
 advance manifested in a better understanding of the value of the 
 roentgenogram in determining pathologic conditions, the result being 
 more rational practice. 
 
 Chapters XII and XIV are devoted to an equally progressive 
 development in the discovery of new substitutes for cocain which are 
 less toxic and equally effective in the removal of pain. With marked 
 
PREFACE XI 
 
 improvement in the technic of handling these new products local 
 anesthesia has become much more generally used by practitioners of 
 dentistry than before. It has been recognized that local anesthesia 
 was more desirable than any other anesthetic in many respects when the 
 operation was to be performed in the dental office where it was difficult 
 to prepare the patient properly and equally difficult to protect him 
 after the operation. Not until the advent of the new product novocain 
 or procain, together with improved technic, however, could local 
 anesthesia be used so satisfactorily for so many operations, especially 
 the extraction of teeth. 
 
 The recent attention given to work in cavity preparation by studying 
 the location and direction of progress of caries and the extension of the 
 cavity walls into relatively immune areas for caries prevention has 
 seemed to warrant a somewhat lengthy consideration of this subject, 
 first, because in. itself, it is a preventive measure, and second, because 
 it has been regarded fundamental to all work which involves restora- 
 tions for lost tooth tissue. 
 
 To have made this work in true monographic style with references 
 to all of the authors of every statement would have resulted in a book 
 of impracticable size and form. The policy that has been adopted 
 provides, as a rule, for reference to authorities for facts that have not 
 received general recognition. 
 
 The editor takes this occasion to express his deep sense of apprecia- 
 tion of the uniform courtesy and spirit of helpfulness which have 
 characterized the attitude of all his collaborators in this work, and 
 their willingness to sacrifice personal interests to the thoroughness 
 and accuracy of the work as a whole. To express adequately my 
 appreciation of the generous support accorded by my colleagues, Drs. 
 Bunting and Lyons and Miss Nita Faught and Miss Hazel V. Kramer 
 in the preparation of this work is not possible. Second, only to the 
 contributors, should these persons who have been intimately asso- 
 ciated with me, receive credit for any help that this work may be to 
 the progress of dentistry, 
 
 Marcus L. Ward. 
 
LIST OF CONTRIBUTORS. 
 
 RUSSELL W. BUNTING, D.D.Sc, 
 
 Professor of Dental Histology and Pathology, University of Michigan. 
 
 WILLIAM A. CAPON, D.D.S., 
 
 Assistant Professor of Dental Ceramics, The Thomas W. Evans Museum and 
 Dental Institute, School of Dentistry, LTniversity of Pennsylvania. 
 
 JOHN V. CONZETT, D.D.Sc, 
 
 Author of Many Valuable Articles on Operative Dentistry. 
 
 EDGAR D. COOLIDGE, D.D.S., 
 
 Professor and Head of the Department of Materia Medica and Therapeutics, 
 University of Illinois. 
 
 ARTHUR HOPEWELL-SMITH, Sc.D., L.D.S., M.R.C.S., L.R.C.P., 
 
 Professor of Dental Histology, Histopathology and Comparative Odontology, 
 The Thomas W. Evans Museum and Dental Institute, School of Dentistry, 
 University of Pennsylvania. 
 
 CHALMERS J. LYONS, D.D.Sc, 
 
 Professor of Oral Surgery and Consulting Dental Surgeon to the University 
 Hospital, University of Michigan. 
 
 FREDERICK B. NOYES, B.A., D.D.S., 
 
 Professor and Head of the Department of Orthodontia and Dental Histology, 
 University' of Illinois. 
 
 HERMANN PRINZ, A.M., M.D., D.D.S., 
 
 Professor of Materia Medica and Therapeutics, The Thomas W. Evans Museum 
 and Dental Institute, School of Dentistry, University of Pennsylvania. 
 
 KURT H. THOMA, D.M.D., 
 
 Lecturer on Oral Histology and Pathology, Harvard University. 
 
 ROSCOE H. VOLLAND, M.D., D.D.S., 
 
 Professor of Oral Pathology and Operative Technic, Iowa University. 
 
 MARCUS L. WARD, D.D.Sc, 
 
 Professor of Dental Metallurgy and Crown and Bridge Work, Dean, College 
 of Dental Surgery, University of Michigan. 
 
CONTENTS. 
 
 CHAPTER I. 
 
 THE ANATOMY OF THE TEETH OF MAN 17 
 
 By Arthur Hopewell-Smith, Sc.D., L.D.S., M.R.C.S., L.R.C.P. 
 
 CHAPTER II. 
 
 DENTAL HISTOLOGY WITH REFERENCE TO OPERATIVE 
 
 DENTISTRY 51 
 
 By Frederick B. Noyes, B.A., D.D.S. 
 
 CHAPTER III. 
 PREVENTIVE DENTISTRY 122 
 
 By Russell W. Bunting, D.D.Sc. 
 
 CHAPTER IV. 
 
 INSTRUMENTATION, CAVITY PREPARATION, AND THE FILLING 
 OF TEETH WITH GOLD FOIL, GOLD INLAYS, AMALGAM, 
 CEMENTS AND GUTTA-PERCHA 179 
 
 By John V. Conzett, D.D.Sc, and Roscoe H. Voll.\nd, M.D., D.D.S. 
 
 CHAPTER V. 
 
 GOLD INLAYS AS BRIDGE ATTACHMENTS 284 
 
 By Marcus L. Ward, D.D.Sc. 
 
 CHAPTER VI. 
 
 HIGH FUSING PORCELAIN INLAYS 299 
 
 By WILLM.M A. Capon, D.D.S. 
 
 CHAPTER VII. 
 
 PROPERTIES OF FILLING MATERIALS 339 
 
 By Marcus L. Ward, D.D.Sc. 
 
 CHAPTER VIII. 
 
 THERAPEUTIC PROCEDURES IN THE TREATMENT OF 
 
 INFECTED ROOT CANALS 411 
 
 By HER^LVN Prinz, A.M., M.D., D.D.S. 
 
XVI CONTENTS 
 
 CHAPTER IX. 
 
 THE PREPARATION AND FILLING OF ROOT CANALS . . . 431 
 By Edgar D. Coolidge, D.D.S. 
 
 CHAPTER X. 
 
 PATHOLOGY AND TREATMENT OF HYPERSENSITIVE DENTIN 454 
 By Hermann Prinz, A.M., M.D., D.D.S. 
 
 CHAPTER XL 
 
 DISCOLORED TEETH AND THEIR TREATMENT 467 
 
 By Hermann Prinz, A.M., M.D., D.D.S. 
 
 CHAPTER XII. 
 
 LOCAL ANESTHESIA 498 
 
 By Hermann Prinz, A.M., M.D., D.D.S. 
 
 CHAPTER XIII. 
 PYORRHEA ALVEOLARIS 527 
 
 By Russell W. Bunting, D.D.Sc. 
 
 CHAPTER XIV. 
 
 E?:TRACTI0N of teeth, and other surgical procedures 583 
 By Chalmers J. Lyons, D.D.Sc. 
 
 CHAPTER XV. 
 
 PRINCIPLES OF ORTHODONTIA FOR THE GENERAL PRACTI- 
 TIONER 653 
 
 By Frederick B. Noyes, B.A., D.D.S. 
 
 CHAPTER XVI. 
 
 ROENTGEN DIAGNOSIS IN DENTISTRY 675 
 
 By Kurt H. Thoma, D.M.D. 
 
OPERATIVE DENTISTRY. 
 
 CHAPTER I. 
 
 THE ANATOIVIY OF THE TEETH OF MAN. 
 
 By ARTHUR HOPEWELI^SMITH, Sc.D., L.R.C.P., M.R.C.S... L.D.S. 
 
 Introduction. — In determining the nature of his contribution to this 
 volume the author has been actuated by the main conception of pre- 
 senting the subject with due regard to the scope and character of the 
 entire work, to the average requirements of the general reader, and to 
 the limitations of allotted space. It is obvious that for a fuller treat- 
 ment of the subject text-books especially dealing with dental anatomy 
 should be consulted. Complete discussions of many of its branches 
 are not germane to the consideration of special technical methods of 
 immediate interest to the practitioner, important though they undoubt- 
 edly are to the anatomist, pathologist and surgeon. 
 
 Consequently, this chapter includes brief descriptions of the anatomy 
 of the dental organs which should influence daily clinical work, and 
 omits much of purely academic interest. The facts of dental histology 
 and histogenesis, the problems of dental physiology, and the resultant 
 principles of dental pathology cannot be here set forth: they must be 
 sought for elsewhere. 
 
 At the same time it must be noted that the earnest, progressive 
 seeker after truth should not be contented with what is here so concisely 
 detailed. Many recent advances have been made; but many debated 
 and debatable side issues increasingly demand attention. Many old 
 theories have been, and will still continue to be relegated to the past, 
 and the newer teachings of anatomy, medicine, surgery and pathology 
 employed and applied to the study of the science and art of dental 
 surgery. 
 
 The reader will be well advised, therefore, to refer to modern text- 
 books, written for the specific purpose of providing an enlarged, sure, 
 clarified, common-sense and scientific basis for the building up of the 
 2 (17) 
 
18 ANATOMY OF THE TEETH OF MAN 
 
 higher degrees of knowledge and learmng demanded today of the 
 practitioner of dental surgery. 
 
 The use of a stricter nomenclature, the appeal of a closer correlation 
 of science and practice, the recognition of the fact that the teeth are 
 organs of the body, acting in siiis modibus as part controllers of its well- 
 being, should be strongly insisted upon, if advancement in the interpre- 
 tation of symptoms and the diagnosis and treatment of diseases of the 
 oral cavity is desired, as it is certainly desirable. 
 
 In view of the foregoing the subject may be shortly considered 
 under the following headings: (I) Definitions. (II) Numeration. 
 (Ill) Morphology. (IV) Articulation. (V) Descriptive Gross Anatomy. 
 (VI) Relationships. 
 
 I. DEFINITIONS. 
 
 A. Collective. — ^Teeth may be defined as hard bodies generally* 
 found in the mouth, developed from the ectoderm and mesoderm, 
 articulated to the skeleton but not forming part of it, whose major 
 general functions are concerned with the comminution of food. 
 
 B. Individual. — The teeth of man, as of all the primates, are classi- 
 fied as incisors, canines, premolars and molars — so-called from their 
 predominant anatomic and physiologic characteristics, viz., those used 
 for sectorial purposes, those greatly developed in the canidce (dogs, 
 wolves, etc.), those occupying a position in front of the molars, and 
 those used after the fashion of a flat millstone for grinding food. 
 
 The maxillary incisors in each half of each jaw are two in number, 
 in articulation with the premaxillary bones, that is, the bones which 
 intervene between the right and left premaxillary suture. They are 
 called the first and second incisors. The older terminology — " centrals" 
 and "laterals" — is incorrect for several reasons. The words have 
 no specific meaning. The so-called "central" is central to no anatomic 
 entity. It occupies a position either to the right or to the left of 
 the interpremaxillary suture — ^which corresponds to the midline of the 
 jaws and face — on the endognathion,^ and is probably the homologue 
 of the first incisor of mammalian dentitions. The so-called "lateral" 
 similarly may assume a position in the dental arch on either side of the 
 labial or palatal surfaces of the first incisor, appears to be the homo- 
 logue of the second incisor in the mammalian dentitions, and is in 
 articulation with the mesognathion} The mandibular incisors are those 
 teeth attached to the lower jaw which, in occlusion, correspond directly 
 with the upper teeth. 
 
 * Teeth may also be found in the nasal fossse.i" sigmoid notch of the mandible, ^^ 
 ovarian teratomata,^ and testes,^ and attached to the temporal bone^ and external audi- 
 tory meatus.' 
 
DEFINITIONS 
 
 19 
 
 The maxillary canine is that tooth — no matter what its shape or size 
 — which is in articulation with the maxillary bone (the exognathion) ,^ 
 in that region immediately beyond the premaxillary suture. The 
 mandihular canine is that tooth in the mandible which in occlusion 
 passes in front of its maxillary congener. In the carnivora. for instance, 
 a space exists between the maxillary incisors and canine for the purposes 
 of the accommodation of this tooth. This space is termed a "dias- 
 tema," literally meaning "an interval." It is occasionally found in 
 man as a normal interruption to the regularity of the dental arch. In 
 the typically herbivorous animal there are no incisors or canines in 
 the upper jaw. The front portion of the mandible, however, carries 
 four teeth on each side of the suture at the symphysis menti. Of these 
 the fourth or outermost; is small and incisiform in shape. It is, never- 
 theless, a canine, its period of development and eruption being con- 
 siderably later than that of the three incisors, it being impossible for 
 mammals (except the polyprotodont marsupials) normally to possess 
 more than three incisors on each side of the middle line of the face. 
 
 Fig. 1. — Palatal aspect of maxillae of child aged five and a half years, showing various 
 sutures. 1, interpremaxillary suture; 2, endognathion; 3, mesognathion; 4, exognathion; 
 5, premaxillary suture; 6, median maxillary suture. 
 
 The premolars are two in number on either side of each jaw. They 
 are so-called because they are situated immediately in front of the 
 permanent molars, and in eruption have displaced two predecessors, 
 viz., the deciduous molars. They are termed the first and second 
 premolars, though they probably represent the third and fourth 
 premolars of the typical mammalian dentition. These teeth have 
 been generally known as "bicuspids," But recent trend of thought, 
 determined by a careful examination of many specimens in the mouth 
 of man, and by a study of the anatomic relationships of man to the 
 primates, show that the term is a misnomer, for the following reasons: 
 the crowns of many maxillary canines possess a prominent cusp on 
 their lingual aspects. Incisors frequently have a well-defined prominent 
 lingual tubercle. In both instances this is an elevation of the internal 
 
20 ANATOMY OF THE TEETH OF MAN 
 
 part of the cingulum. They are, therefore, bicuspid ate. Further, 
 the first mandibular premolar has often the lingual cusp so ill-defined 
 and underdeveloped that it appears merely as a raised tubercle and 
 cannot properly be called a cusp. The second mandibular premolar 
 is frequently tricuspidate, and may on occasion be multi-tuberculate. 
 These objections cannot be raised, however, if the teeth are considered 
 as the homologues of the mammalian dentition. 
 
 The 'permanent molars are three in number in each half of each jaw, 
 erupt in typical diphyodonts behind the milk molars, and have no 
 predecessors. The existence of a fourth molar is impossible; no 
 typical mammal possesses such a tooth. The "fourth molar" of some 
 authors^ is a more or less molariform supernumerary tooth. The 
 deciduous molars are those teeth which have been displaced during the 
 growth and eruption of the subjacent premolars. They are correctly 
 termed the first, second and third molars in the first instance and the 
 first and second molars in the second instance. 
 
 n. NUMERATION. 
 
 There is a marked reduction in the number of the teeth of man 
 compared with that of the typical mammalian dentition, as seen, for 
 example, in the mole, young horse and pig. Here the full dental 
 formula gives on one side of either jaw three incisors, a canine, four 
 premolars and three molars. Adopting the usual symbols this may be 
 represented graphically: 
 
 I I, C 1, Pm f, M, f = 22 or X 2 = 44 in the entire oral cavity. 
 The normal human permanent dentition is denominationally and 
 numerically expressed thus: 
 
 1 f , C I, Pm f , M f = 16, or X 2 = 32; 
 and the deciduous series: 
 
 i f , c 1, m f = 10, or X 2 = 20. 
 
 f , c 1, m f = 10, or X 2 = 
 
 Reasons for the Departure from the Typical Mammalian Formula. — 
 
 Examination of the preceding formulae shows that man has twelve 
 permanent teeth less than the typical number — four incisors and 
 eight premolars. The factors in the production of this condition are 
 probably^'' as follows: 
 
 1. Incomplete evolution of certain teeth which are practically 
 functionless, such as the third molars, following the rule of degeneracy 
 of other organs of the body, as exemplified, for instance, in the vermi- 
 form appendix and the plica semilunaris, which are important in the 
 rabbit, and as the third eyelid of birds and Hzards, etc. 
 
MORPHOLOGY 
 
 21 
 
 2. The progressive enlargement of the most actively functional 
 organs, as typified in the comparatively great size of the fourth pre- 
 molar in the felidce, the dynamic effects of unusually great muscular 
 action in the zygomatic region; and 
 
 Fig. 2. — Left side of jaws of man with permanent teeth in situ. 
 
 3. The shortening of the length of the entire jaw of man in com- 
 parison with that of many of the mammalian series of animals. This 
 reduction in the antero-posterior direction results in the crowding out 
 of teeth which, as organs for the comminution of food, can best be 
 spared. While the general size and shape of the teeth of modern man 
 have undergone little change during his evolution, his jaws have. 
 There is less room in his mouth for the attachment of his teeth than 
 there was in the more spacious oral cavity of his prehistoric simian 
 ancestor. 
 
 III. MORPHOLOGY. 
 
 In attempting to affix the conception of a geometrical basis to any 
 consideration of the shapes of the organs of man, it must be remembered 
 that, in spite of the necessity, when describing such organs, of adopting 
 mathematical ideals, it was probably never the intention on the part 
 of nature to construct an architectural type which would be completely 
 subservient to geometrical pattern or design. If it were so, then of 
 
22 ANATOMY OF THE TEETH OF MAN 
 
 all the organs of the body his teeth lend themselves most to this treat- 
 ment; more so than his palate or his dental arches. 
 
 It is usual, however, to describe the shapes of the teeth as being 
 dependent, especially as far as the roots are concerned, on the mor- 
 phological variations of that geometrical figure known as a cone. The 
 roots of human teeth are conical, thoroughly adapted to their unique 
 articulation with the alveolar processes of the jaws. Roots may be 
 cylindrical, flattened laterally, straight, curved or twisted. 
 
 With regard to the evolution of the pattern of their crowns three 
 schools of thought may be cited as holding concurrent views, varying 
 chiefly by reason of the differences of the viewpoint of their genesis 
 and development. 
 
 Of these the simpler is the theory of (A) the fusionists,^*^ ^^ ^^ ^'^ 
 who hold that in consequence of the decrease in shape and size of the 
 jaws, haplodont (cone-shaped) teeth may exist per se, or, becoming 
 fused, may produce a molariform pattern. (B) The trituberculists^^ ^^ 
 have advanced the theory that, during the course of evolution from 
 the primitive type, haplodont teeth may develop on the chief cone, 
 subsidiary cusps in anterior, posterior and lateral directions. A 
 further extension of the tubercular theory may be called (C) the multi- 
 tubercular theory,^^ 
 
 A discussion as to the merits of, and objections to, these views is 
 not relevant to this article. It may, however, suffice to say that prob- 
 ably the crowns of the human incisors are merely flattened cones, 
 that the canine largely retains its primitive shape, while the molariform 
 crowns of the three posterior teeth are chiefly due to a longitudinal 
 fusion of original haplodont cones. In the case of the premolars it is 
 believed that the internal cusp is a modification of the cingulum, in 
 which an elevation of its inner part produces a tubercle of varying 
 proportions. 
 
 The reasons for the diversities in shape of the crowns of teeth may 
 be ascribed to . the operations of the laws of adaptive modification, 
 which demonstrate that, following the deterioration and suppression 
 of disused and unwanted organs and the more complete morphological 
 development of really necessary and much used organs, certain slow, 
 progressive modifications from few and simple forms occur. Of all 
 the teeth the third maxillary molar and probably the second maxillary 
 incisor are the least used as mechanical agents. These teeth, par- 
 ticularly the former, have a tendency to undergo suppression and to 
 evince in their coronal patterns traces of retrogressive and unstable 
 characteristics. In short: the law which governs the fixed mor- 
 phological features of the teeth is founded upon the requirements of 
 nature in connection with the provision of an organ or of several 
 
ARTICULATION 23 
 
 organs most suitably designed and constructed to accomplish the very 
 definite purpose for which they were intended. 
 
 Succession. — Man, like most animals, is a diphyodont animal, 
 i. e., he possesses two sets of teeth, the deciduous or milk, and the 
 permanent series. A third set, occasionally spoken of by the unlearned, 
 cannot exist. Vestigial dental remains are exceptionally found in the 
 human jaws and are believed by some evolutionists^^ to point to a 
 reversion to a reptilian dentition in which a polyphyodont condition 
 obtains. 
 
 IV. ARTICULATION. 
 
 Teeth are attached to the jaws by means of a unique joint or articu- 
 lation, termed "gomphosis," exactly imitating the arrangement of a 
 nail or peg when received into a hole or mortise in a piece of wood; 
 hence the term. Gomphosis is a variety of synarthrosis^^ ^* — a fixed, 
 immovable joint, as exemplified in the methods of union of the bones 
 of the cranium. It is limited to the teeth. The socket containing 
 the cone-shaped root is termed the alveolus, and those portions of the 
 jaws which support the sockets are called the alveolar processes. The 
 teeth are immovably held in position through the cementum on the 
 inner side by a strong fibrous attachment to the lamina dura — a thin 
 sheet of compact bone surrounding their alveolar sockets on the outer 
 side — through the intervention of a dense, firm layer of connective 
 tissue called the alveolo-dental periosteum. 
 
 Just as it may be affirmed without fear of refutation that the masti- 
 catory organs of modern men are degenerate and unfitted to perform 
 properly their functions throughout the lifetime of the individual, 
 so may it be stated that their sockets are equally unsuited to their 
 desired requirements. It is the rule that they should atrophy and 
 disappear with the incidence of age. 
 
 The terminal margins of the sockets of the teeth of man are of a 
 degenerate character for the following reasons:^'' 
 
 1. Absence of muscular attachment. No muscles or parts of muscles 
 arise from or are inserted into the alveolar processes of the jaws, except 
 a few stray fibers of the buccinator in the neighborhood of the maxillary 
 molars. The fundamental function of bone is therefore entirely absent 
 in this situation. 
 
 2. The unique character of the structure of the bone does not 
 completely conform either to the compact or cancellous varieties. 
 
 3. Inadequacy of the blood supply tends to produce anemia of the 
 parts, and this, when long continued, is likely to lead to atrophy. 
 
 4. Physiologic resistance to disease and nutritional equilibrium are 
 
24 ANATOMY OF THE TEETH OF MAN 
 
 easily and readily lowered and disturbed by the extreme tenuity and 
 other histologic features of the external and internal alveolar plates. 
 
 5. There is a modification of the usual function of bones, which, in 
 this particular instance, is only required to support and afford attach- 
 ment to the roots of teeth. 
 
 V. DESCRIPTIVE GROSS ANATOMY. 
 
 A. The Permanent Series. — 1. The Maxillary Teeth.^ — ^The First 
 Incisor. — In articulation with the endognathion and placed on either 
 side of the intermaxillary suture, which corresponds to the midline of 
 the jaw and face, this tooth with its congener of the opposite side forms 
 one of the most striking objects of the dental series. The graceful 
 size and shape of its crown make it of great importance in its relation- 
 ship to the other teeth and to the aesthetic bearing it has on the features 
 generally. 
 
 It is usually placed in close proxinaity to its fellow in the other maxilla, 
 but frequently in early life a space exists between the two first incisors. 
 This is due to an excessive development and consequent enlargement' 
 of the bone of the alveolar sockets of the teeth, particularly at the side 
 nearest the suture, a hypertrophy probably induced and continued 
 by the presence and action of a large frenum labii, w^hich is inserted 
 into the soft tissues of the labial aspect of the alveolar process. 
 
 The crown has four surfaces, six borders, and two angles, named 
 respectively (1) labial, or vestibular, or external, or anterior, (2) 
 lingual, caval, internal, or posterior, (3) mesiaP and (4) distal; incisive 
 edge or inferior border, gingival edge or superior border, and mesio- 
 anterior and mesio-posterior and disto-anterior and disto-posterior 
 borders. The angles are mesial and distal. 
 
 Surfaces.- — ^The labial is the largest of all the surfaces. It is markedly 
 convex from above downward and from side to side. Its upper border 
 is narrow and rounder than the lower, thus making it triangular m 
 outline. Smooth usually, it may be traversed by numerous horizontal 
 ridges or pits or depressions, and is frequently discolored and pig- 
 
 1 The terms "mesial" and "distal," common in clinical parlance, are not strictly 
 anatomically correct. It is the rule in general anatomy to designate that part or surface 
 of a long bone nearest to the larger joint as "proximal," that away from the large joint 
 "distal." Thus, in the femur the part of the bone at the hip is called the "proximal 
 extremity," that at the knee the "distal extremity." So it should be with the teeth. 
 Owing to the shape of the dental arches the mesial surfaces of the incisors face in exactly 
 the same direction — toward the midline — as do the lingual surfaces of the premolars 
 and molars, their distal surfaces as the buccal surfaces of these teeth. It is more in 
 accordance with anatomic usage to consider the so-called "mesial surface," i. e., the 
 part further away from the joint, viz., the temporo-mandibular articulation — as the 
 "distal surface," and the so-called "distal" as the "proximal surface," For the conven- 
 ience of the reader, however, the usual clinical terms will be here adopted. 
 
DESCRIPTIVE GROSS ANATOMY 25 
 
 merited as the result of either congenital or acquired conditions. Oc- 
 casionally a median vertical ridge may divide the surface into two 
 unequal parts. 
 
 The lingual surface is remarkable for its pronounced double con- 
 cavities. Smaller than the above, with thickened and elevated bound- 
 aries, it is triangular in shape, the base being at the incisive edge. A 
 diminutive cusp or tubercle frequently appears at the gingival margin. 
 It represents an elevation of the cingulum. 
 
 On the mesial aspect the crown is slightly convex in both vertical 
 and lateral directions. It is enclosed by the rounded mesio-anterior 
 and mesio-posterior borders, which in many instances are scarcely 
 elevated from the general level of the surface and therefore indistin- 
 guishable to any extent. The upper borders follow more or less closely 
 the outline of the surface itself. Of its two parts, that directed to the 
 external side is shorter than that directed to the internal side. 
 
 The distal surface is more convex than the former, a little larger 
 generally, as a consequence of the superior border not curving down- 
 ward so markedly. The whole of this doubly-convex surface passes 
 into the disto-anterior and disto-posterior borders without any per- 
 ceptible interruption. 
 
 The incisive edge is blunt, slightly convex and slightly thicker toward 
 the mesial side. Three tubercles may be present here at birth. 
 
 The gingival edge varies over the different aspects of the crown. On 
 the labial side it forms part of the circumference of a circle. Lingually 
 it is considerably flattened — nearly in a straight line, mesially it dips 
 down some considerable distance near the middle portion toward the 
 mesial angle, and distally it is less curved than in the last-named 
 situation. 
 
 The mesio-anterior, mesio-posterior, disto-anterior and disto-posterior 
 borders are all rounded and smooth, and in the majority of instances 
 are not elevated over and above the surfaces which they enclose. 
 
 Of the angles, the mesial is nearly a right angle, the distal is obtuse. 
 
 The neck of the tooth is clearly defined, on account of the prominence 
 of the free edge of enamel and its relationship with the cementum 
 above. It does not lie in the same horizontal plane, but as it passes 
 around the tooth it is elevated or depressed, according to the situation. 
 Thus labially and lingually it is very much raised, distally and mesially 
 it is considerably depressed toward the incisive border of the crown. 
 
 The root is normally almost a cylindrical cone and the alveolar 
 socket also necessarily cylindrical. Usually straight, it may be de- 
 flected slightly toward the middle line. Flattened laterally, it becomes 
 at times somewhat triangular in outline. It may rarely be bifurcated, 
 the second root being placed on the lingual side. 
 
26 
 
 ANATOMY OF THE TEETH OF MAN 
 
 The pidiJ cavity generally follows in shape the outline of the tooth 
 itself, viz., two cones of dissimilar size placed together at their bases. 
 Of these the radicular portion is considerably the larger. Viewed in 
 a mesio-distal direction the lower part of the pulp cavity is the broadest, 
 and is divided into three cornua, of which the central — the smallest — 
 disappears at about the fifteenth year. The root canal is tube-like, 
 narrow and straight. 
 
 A B c D 
 
 Fig. 3. — Maxillary first incisor. A, labial surface; B, lingual surface; C, mesial surface; 
 
 D, mesio-distal section. 
 
 The calcification of this tooth begins during the first year after 
 birth ;^ its apical foramen forms about the tenth to eleventh years,^ 
 and it is erupted at the seventh year and ninth month.^^ 
 
 Length, approximately 25 mm.;^^ width, 9 mm. 
 
 Identification, from a number of specimens isolated from the mouth, 
 can be effected by placing the tooth in a horizontal position, with 
 convex coronal surface upward and root away from the observer, and 
 noting the more acute angle of the incisive edge. This points to the 
 side to which the tooth belongs. 
 
 Methods of normal occlusion. This tooth completely overlaps the 
 upper sixth of the labial surfaces of the first and second mandibular 
 incisors. 
 
 The Second Incisor. — ^This tooth, the second from the midline of 
 the face, in articulation with the mesognathio7i, is situated on the 
 distal side of the first incisor. It is frequently suppressed. It simu- 
 lates, though on a smaller scale, the first incisor in its main archi- 
 tectural features. 
 
 Similarly to the first incisor the croum has four surfaces, six borders 
 and two angles. 
 
 Of all the surfaces the labial is the largest, and differs from that of 
 the other incisor in the more pronounced diminution in size as it 
 approaches the gingival margin. Hence the whole aspect is very 
 triangular in outline. Markedly convex in both directions it assumes 
 
DESCRIPTIVE GROSS ANATOMY 27 
 
 a transitional type of shape between the flatter first incisor and the 
 more conical canine. Of the two convexities, that from side to side is 
 the more appreciable. Its superficial markings are not so well defined 
 as in the other incisor. 
 
 Lingually the appearance of the crown follows that of the first 
 incisor, save that it is smaller in every dimension. Its concavities 
 are greater. A slight vertical ridge may be formed at times on this 
 surface, separating two deep concavities. The internal cingulum may 
 be modified into a cusp. 
 
 The mesial surface is slightly larger than the distal. It is flattened 
 from side to side and slightly convex from above downward. It passes 
 imperceptibly into the mesio-anterior and mesio-posterior borders. 
 
 The distal surface is much more convex in both directions than the 
 former. It is smaller in area, being vertically shorter and encroached 
 upon by the disto-anterior and dis to-posterior borders. 
 
 The incisive edge is broad and round and does not present the blade- 
 like appearance as in the first incisor. It is short in a mesio-distal 
 direction, largely through the shape of the distal angle. Three tubercles 
 may frequently be seen. 
 
 The gingival edge is very narrow compared with the former, par- 
 ticularly on its labial aspect. It forms the arc of a much smaller circle 
 than in the first incisor. The cervical edge of enamel in this locality is 
 not very pronounced. 
 
 Of the borders, all are considerably rounded, flat and broad, so much 
 so that it is often impossible to define the actual limits of surface and 
 border. This condition is more obvious on the distal than on the mesial 
 side. 
 
 The angles are obtuse, particularly the distal. 
 
 The neck copies that of the first incisor, but the undulations are less 
 marked and the constriction less severe. 
 
 The Root. — Cone-shaped and flattened laterally the labial and 
 lingual sides of the root are broader than the other two surfaces. Of 
 these two the lingual is the narrower. The root is generally straight 
 but may be deflected toward the distal side, and may be bifurcated. 
 When in situ it has a tendency to be directed toward the midline of 
 the palate. Hence it follows that a dento-alveolar abscess resulting 
 from a septic pulp points over the palate in the cavum oris. 
 
 The Pulp Cavity. — Compared with the general size of the tooth 
 itself the pulp cavity is the largest of all; compared with that of the 
 first incisor it is a little smaller in every dimension. Two cornua 
 exist, as in the last-named tooth; the one on the mesial side being 
 frequently the largest. The root canal is a narrow tube; an accessory 
 root canal is a fairly common abnormality. 
 
28 
 
 ANATOMY OF THE TEETH OF MAN 
 
 Calcification begins during the first twelve months, finishes with 
 the formation of the apical foramen at the tenth to the eleventh year, 
 and the tooth is erupted at about the third year and ninth month. 
 
 It measures approximately 23 by 6.5 mm. in greatest length and 
 diameter. 
 
 Identify similarly to the first incisor. 
 
 Occlusion. — ^The lingual surface occludes with the upper sixth of 
 half the labial surfaces of the mandibular second incisor and canine. 
 
 A B 
 
 Fig. 4. — Maxillary second incisor. A, labial surface; B, lingual surface; C, mesial 
 
 surface; D, distal surface. 
 
 The Canine. — This important tooth is the third from the midline 
 of the face, its socket occupying the alveolar process of the exog- 
 nathion. Situated at the angle of the alveolar processes of the upper 
 jaw, in possession of a large root, and producing the canine eminence 
 behind the canine fossa on the facial surface of the maxillary bonC; 
 the tooth is remarkable for its size, strength and general appearance. 
 It is by far the largest tooth in the anterior part of the dental series. 
 
 The crown, a somewhat flattened cone, has four surfaces, six borders 
 and two angles. 
 
 The lahial surface, the largest of the four, is slightly convex from 
 above downward and more so from side to side. It forms the rough 
 outline of a pentagon, having one side above at the gingival margin^ 
 a second and third below at the cutting edge, and in front and behind 
 a fourth and a fifth, joining the extremities of the others. Frequently 
 this surface is divided by a median ridge into two unequal parts, of 
 which the anterior is the smaller. 
 
 On the lingual surface, which presents the outline of a five-sided 
 figure, are two deep depressions separated by a vertical ridge, which 
 terminates below at the extremity of the cusp, and above very often 
 in an accessory cusp of varying size, which, like that of the first incisor, 
 represents an elevation of the internal cingulum. Of these concavities 
 that on the distal side is the larger. 
 
 The mesial surface is flattened and smaller in extent than that of 
 
DESCRIPTIVE GROSS ANATOMY 
 
 29 
 
 the opposite side through the undue encroachment of the root at the 
 cervical margin. It is flat, triangular, with an indented base and 
 broad apex, and is generally on the same level as that of the root. 
 Hence the upper edge of enamel is very slightly elevated. 
 
 Distally a unique characteristic of the canine appears. This is a 
 prominence, not amounting to a definite tubercle or cusp, large in 
 extent, and situated at the lower part of the surface at the junction of 
 what would represent in the incisors the disto-anterior and disto-pos- 
 terior borders. The upper border of this surface is almost on a hori- 
 zontal plane. The canine does not usually possess any well-defined 
 borders. All its surfaces are more or less rounded and smooth. 
 
 Of the angles the distal is the more obtuse. At times they may be 
 raised into prominences w^hich give the appearance of a tricuspidate 
 tooth. 
 
 The neck forms a gentle undulating line which, labially, is part of a 
 flattened arc of a circle, and extends downward slightly on the mesial 
 and distal aspects, ending lingually in a nearly horizontal direction. 
 
 The root is an extremely elongated, flattened cone, of which the 
 mesial aspect is the broader and the lingual the narrower in diameter. 
 Two vertical grooves can usually be noted, that on the mesial side 
 being the deeper. The root, when unduly lengthy, may communicate 
 with the maxillary sinus. 
 
 The 2J^<?2^ cavity extends into the coronal region in the form of one 
 cornu. In the crown it is almost triangular in outline; at the neck 
 nearly cylindrical ; at the junction of the upper two-thirds and the lower 
 third compressed from side to side; and at the apex cylindrical. 
 
 A B CD 
 
 Fig. 5. — Maxillary canine. A, labial surface; B, lingual surface; C, mesial surface; 
 
 D, labio-lingual section. 
 
 Calcification begins during the third year and is completed from the 
 twelfth to the thirteenth. Eruption occurs at about the tenth year and 
 
30 ANATOMY OF THE TEETH OF MAN 
 
 sixth month, thus precedmg the complete formation of the apical 
 foramen. 
 
 Average length and width 27 mm. and 8 mm. 
 
 Identification can be effected by the same means as for the incisors. 
 The disto-coronal prominence points to the side opposite to that to 
 which the tooth belongs. 
 
 Occlusion. — By its lingual surface it occludes with the labial aspect 
 of the corresponding tooth in the lower jaw and the anterior part of 
 the upper portion of the labial surface of the mandibular first premolar. 
 
 The First Premolar. — ^Fourth from the front this tooth in man 
 probably represents the third premolar of the typical mammalian 
 dentition, thus following the general rule that when premolars are 
 absent from the dentition of an animal those nearest the canine are the 
 most likely to be suppressed. The definition of the premolars already 
 given suffices to indicate that these teeth are situated in the jaw in 
 front of the permanent molars and that they have displaced deciduous 
 molariform predecessors. It should further be noted, as will presently 
 appear, that a second mandibular premolar may present many cusps 
 or tubercles, and cannot, therefore, be strictly called a "bicuspid" at 
 all. 
 
 This tooth may be in relation with the antrum of Highmore in its 
 facial portion. 
 
 Totally unlike the preceding, the first premolar possesses a crown 
 with five surfaces, a neck, and a root or roots. 
 
 The crown presents for examination a labial, lingual, mesial, distal 
 and a morsal or occluding surface. 
 
 The shape of the labial surface in typical examples combines the 
 mathematical outlines of the pointed cutting edge of the canine and 
 the constricted neck of the second incisor. It is slightly convex from 
 above downward and more so from side to side. The median ridge and 
 lateral vertical grooves commonly seen on the corresponding surface 
 of the canine are often here entirely absent, the whole area being quite 
 smooth. The general outline resembles somewhat that of a diamond, 
 with the upper angle flattened. 
 
 A great resemblance exists between the lingual surface and the 
 former, the main difference being that its superficies is less in all direc- 
 tions, and the upper angle of the diamond is flatter. No grooves or 
 ridges normally exist. 
 
 The quadrilateral face of the mesial siuface is notable for the thick- 
 ening of its lower border, which in some cases may amount almost to a 
 unique elevation of the cingulum. It is slightly concave vertically and 
 in a labio-lingual direction. 
 
 The distal surface is similar to the above, but instead of being slightly 
 
DESCRIPTIVE GROSS ANATOMY 31 
 
 concave it is somewhat convex. It is rather larger in area, with rounded 
 borders. 
 
 The morsal or occluding surface is roughly trapezoidal in outline. 
 Its mesio-distal diameter is considerably less than its other diameters. 
 The labial border of the figure is the largest of the four, the next 
 largest being the posterior or distal border. The surface is not plain, 
 but is divided topographically into elevations or cusps, depressions or 
 sulci or fissures. Almost in the center of this surface extends a short, 
 deep sulcus which runs forward nearly parallel with the intermaxillary 
 suture. At its anterior (mesial) extremity it runs at an angle outward 
 and forward ; at its posterior (distal) end it runs at a more obtuse angle 
 outward and backward. Frequently in the latter situation it bifur- 
 cates. The chief cusp is on the external part of this surface. It is 
 very large and round on its morsal aspect, sharp and pyramidal on its 
 labial aspect. It is separated by the antero-posterior sulcus from the 
 smaller, blunter internal or lingual cusp. In well-formed specimens 
 the whole of this cusp is round, but in many examples the outermost 
 cusp is apparently formed by the union of four ridges of enamel, one 
 passing forward to the outer mesial angle, another backward to the 
 outer distal angle, another toward the center of the surface, and another 
 uniting with a possibly existing vertical ridge on the labial or buccal 
 surface of the crown. If the sulcus bifurcates at one or either extremity 
 one or two additional eminences of enamel are produced. It is there- 
 fore possible on the lingual side of this surface for two additional cusps 
 to be observed. 
 
 The neck is placed in a nearly horizontal plane, slight undulations 
 occurring on all four faces of the root. 
 
 The root or roots. In about 60 per cent, of cases the first premolar 
 is birooted. In single-rooted specimens, both very flattened surfaces 
 usually present a more or less deep groove, that on the mesial being 
 greater than that on the other side. If these grooves attain any great 
 depth during development the tooth then becomes bifid and birooted, 
 each portion containing a typically-shaped pulp canal. These roots 
 may be quite distinct throughout their whole extent, but generally 
 they are united through two-thirds of their length. Occasionally 
 one lingual and two buccal roots are found. This is probably an 
 expression of atavism. The apical region is frequently divergent and 
 deflected backward. 
 
 In the pulp cavity, which closely conforms to the shape of the crown, 
 the cornu found on the buccal side is the more extensive, penetrating 
 far into the cusp; if two pulp canals exist the division from the common 
 pulp chamber in the crown occm-s at the cervical region. The greatest 
 diameter of the pulp cavity is in the labio-lingual direction. 
 
32 
 
 ANATOMY OF THE TEETH OF MAN 
 
 Calcification commences at about the fourth year, and the apical 
 foramen becomes formed between the eleventh and twelfth. Eruption 
 takes place at about the ninth year, or the ninth year and sixth month. 
 
 Length, 20 mm.; ividth, 6.5 mm. 
 
 Identification. — ^The side of the mouth to which the tooth belongs is 
 indicated by the deeper of the two grooves of the root, when the tooth 
 is placed with its crowai toward the observer and its larger external 
 cusp also in the same direction. 
 
 Occlusion occurs by means of the lingual cusps of the crown coming 
 into contact with the distal ridges of the cusp of the mandibular first 
 premolar, and the mesial ridges of both cusps of the second premolar. 
 
 A 
 
 B 
 
 C D 
 
 Fig. 6. — Maxillary first premolar. A, buccal surface; B, distal surface; C, 
 surface; D, bucco-lingual section. 
 
 mesial 
 
 The Second Premolar. — ^The homologue of the fourth premolar 
 of the tj^ical mammalian dentition, this tooth is the fifth from the 
 midline of the jaws and face. It is more constant than the preced- 
 ing in its morphologic characteristics, and hence appears to undergo 
 fewer anatomic variations. In comparison with the first premolar 
 its crown is generally slightly smaller, shorter, rounder, and its cusp 
 less pointed. The bucco-lingual axis is directed inward and slightly 
 backward, the morsal sulcus, therefore, slightly backward and outward. 
 It appears normally to possess one root and therefore one pulp canal; 
 but two, if not three root canals are quite common. In the latter case 
 a bifurcation of the buccal root has occm-red, more or less along its 
 completed length, and the third canal opens into a common pulp cavity 
 with the other two. Frequent connection with the maxillary sinus 
 exists. 
 
 The Crown. — Of all fom- surfaces the labial or buccal is slightly 
 convex, being flatter than that of the first premolar from above down- 
 ward, and more convex than that tooth from side to side. It is diamond- 
 shaped, and usually free from vertical ridges or grooves. 
 
 Lingually the crown matches very closely the corresponding surface 
 of the first premolar. Indeed it is impossible when regarding these 
 
DESCRIPTIVE GROSS AX ATOMY 
 
 33 
 
 teeth, which have been removed from the same mouth, to determine, 
 by mere inspection of the Hngiial sm-faces, which is the first or which 
 is the second premolar. If there is a difference, it is that the secoad 
 has a romider cusp. For the size of the tooth the upper border of this 
 surface is wider antero-posteriorly and less curved than obtains in the 
 former. 
 
 Of the mesial surface the convexity is not remarkable, but distally 
 it is. Their upper borders pass almost imperceptibly into the Ime 
 of the neck of the tooth. 
 
 The morsal siuface resembles that of the first premolar. It is subject 
 to greater variations, however; its sulcus is shallower and shorter than 
 that there seen. Frequently three slight elevations extend outward 
 from the sulcus, separated by foiu short, narrow grooves, of which the 
 middle are the most pronounced. This divides the surface into several 
 tubercles; as many as five may be present. It is this fact which 
 serves on occasion to differentiate this tooth from the first premolar. 
 The sulcus may bifiucate at its anterior extremity and thus produce 
 another tubercle, which may sometimes attain the size of a definite 
 cusp. 
 
 The plane of the neck is normally horizontal. 
 
 The root is generally A'ery conical in longitudinal outline. Trans- 
 versely flattened, it exhibits btit seldom the definite deep grooves 
 associated with its neighbors. It is not often deflected, but may be 
 bifurcated and possess three root canals. 
 
 The pulp cavity is large in a buccolingual section and extremely 
 narrow in a mesiodistal section. Its cornua do not extend far mto the 
 cusps of the tooth. Of the two the outermost is the greater. 
 
 A B 
 
 Tig. 7. — Maxillary second premolar. A. buccal surface : 
 
 surface: D, bucco-lingual section. 
 
 mesial surface; C, dista 
 
 Calcification begins durmg the fiith year. The apical foramen is 
 closed dm-ing the eleventh to the twelfth year, eruption taking place 
 at the tenth year and third month. 
 
 Length, 22 mm.; mdtli. 5 mm. 
 
 Identification. — It is impossible to determine to which side of the 
 mouth this tooth belongs. 
 3 
 
34 ANATOMY OF THE TEETH OF MAN 
 
 In occlusion the tooth comes into contact with both the mandibular 
 second premolar and first molar; in the first instance by means of its 
 internal cusp and the posterior ridges of the two cusps of the premolar 
 and in the other by means of its internal cusp and the mesio-buccal 
 and mesio-lingual cusps of the molar. 
 
 The First Molar. — Of all the teeth of the human dentition this 
 is undoubtedly the most important. From the viewpoints of palaeon- 
 tology, histogenesis, homology, pathology, surgery and orthodontics, 
 it may be regarded as the most interesting. 
 
 The sixth tooth from the midline of the face attains the highest degree 
 of development in size of all the other posterior members of the series. 
 This is its most striking feature, for the morsal surface of its crown is 
 nearly as great as that of the two premolars put together. It is in 
 association, through its anterior buccal root, with the floor of the 
 antrum, and communicates with the cavuvi oris by means of its 
 palatine root and vestibulum oris by means of its buccal root. Obliquity 
 of the crown is always accompanied by marked obliquity of the roots. 
 It presents for examination a crown, neck and three roots. 
 
 The crown exhibits five surfaces: (i) buccal or external, (ii) lingual 
 or palatine, (iii) mesial, (iv) distal, and (v) morsal or occlusal. 
 
 Quadrilateral in outline the buccal surface extends in the antero- 
 posterior diameter a distance fully twice that of the same diameter 
 of either of the premolars, while its vertical measurements are less 
 than those of the same tooth. It is slightly convex in both directions 
 and is frequently divided into two unequal parts by a perpendicular 
 groove which begins at a slight distance below the cervical margin. 
 Its upper border is short and straight. Its lower border is distinguished 
 by two similar-sized curves — the external portions of the buccal cusps 
 — of which the convexities look downward. 
 
 The lingual surface resembles the preceding to some extent, the main 
 points of difference being the flatter inferior border, the rounder char- 
 acter of the angles of the same and the marked prominence of the 
 vertical groove which often curves backward in its lower part. The 
 distal portion of this surface is much more convex than the mesial. 
 
 Roughly rhomboidal in outline the mesial extensive, flat surface 
 possesses on its lower palatine aspect a pronounced, highly convex 
 slope downward and forward. Its upper border occupies a horizontal 
 plane, but the lower border is deeply indented near the middle and 
 internally carried considerably downward. 
 
 Unlike the former the distal quadrilateral surface is more generally 
 convex in both directions, the convexity being accentuated toward 
 the palatine side. It is free from grooves, and its junction with the 
 neck is hardly perceptible. 
 
DESCRIPTIVE GROSS ANATOMY 35 
 
 The morsal surface in outline is roughly quadrilateral, with rounded 
 angles. It possesses four cusps, an obHque ridge and two main sulci or 
 fissures. According to their position so are the cusps named. They are 
 called the antero-external, or mesio-buccal, the postero-external, or 
 disto-buccal, the antero-internal, or mesio-lingual, and postero-internal, 
 or disto-lingual. 
 
 Of these the largest, most pyramidal and most prominent, is the 
 antero-internal cusp. It is joined to the postero-internal cusp by the 
 oblique ridge, which, near the middle, is traversed by a slight depression, 
 amounting almost to a groove. These two cusps are separated from 
 the other two by the anterior and posterior sulci, the former short, 
 deep, bending at its middle at an acute angle, and thus passing at first 
 from without inward in a straight line, and then suddenly bending 
 forward; and the other beginning near the middle of the surface, 
 sometimes in a pit, and running inward and slightly forward. The 
 antero-external cusp is somewhat triangular in outline and the postero- 
 internal considerably flattened from side to side and from before back- 
 ward. With regard to size it is thus obvious that the dimensions of 
 the individual cusps decrease in the following order: antero-internal, 
 antero-external, postero-external and postero-internal. A fifth cusp 
 may be present as an elevation of the cingulum at the side of the 
 anterior internal cusp. 
 
 The neck occupies a horizontal plane and is unmarked by any notable 
 deviations from a straight line. In section the tooth is rhomboidal in 
 outline at the neck and is also more extensive on the lingual than on 
 the opposite side. 
 
 The Roots. — ^This tooth possesses three roots: (1) The anterior 
 buccal root is broad in the bucco-lingual direction, much flattened and 
 cone-shaped, its central axis looking upward and slightly outward and 
 forward. It is often grooved, especially on its inner side; hence two 
 root canals may exist, both of which terminate in a common apical 
 foramen. (2) The posterior buccal is considerably shorter and smaller 
 than the foregoing, probably normally more divergent, slightly grooved, 
 and consequently less likely to contain two root canals. (3) The pala- 
 tine root is a prominent feature of this tooth. Very divergent, and thus 
 ensuring great stability and strength in its articulation with the maxilla, 
 it is the least flattened of the three. It is frequently deflected and 
 twisted. It measures approximately half an inch in length, the lengths 
 of the others being about three-eighths inch. 
 
 The pulp cavity closely follows in its outline the shape of the crown. 
 At its roof it has three cornua, each extending somewhat into each 
 cusp, and on the floor or " infundibulum" the three openings of the root 
 canal, that on the palatine side being cylindrical, the others laterally 
 flattened. 
 
36 
 
 ANATOMY OF THE TEETH OF MAN 
 
 Calcification occurs in the first instance in about the eighth month 
 of intra-uterine Hfe and is completed during the eleventh or twelfth 
 year, eruption taking place at the sixth year and sixth month. 
 
 A B c D 
 
 Fig. 8. — Maxillary first molar. A, buccal surface; B, mesial surface; C, lingual or 
 palatal surface; D, bucco-lingual section. 
 
 Length. — From the apex of the palatine root to the most prominent 
 part of the crown is 22 mm., of the buccal root to the anterior part 
 of the internal border 21 mm., and of the disto-buccal root to the 
 posterior part of the external border 19 mm. 
 
 Identification. — ^The end of the oblique ridge nearest the observer 
 will point to the side to which the tooth belongs if the tooth is held 
 crown uppermost and the palatine root away from him. 
 
 Occlusion. — ^The mesio-buccal cusp is received into the central sulcus 
 of its lower congener, the disto-buccal cusp into the disto-lingual and 
 disto-buccal cusps and the mesio-buccal and mesio-lingual cusps of the 
 mandibular second molar. 
 
 The Second Molar. — Intermediate in size between the first and 
 third molars, this tooth, in general, follows the architectural plan of 
 the first-named, particularly on the buccal portions of crown and roots. 
 The greatest deviation in pattern from the first molar is to be found on 
 the lingual side. The opening of Stenson's duct is usually opposite this 
 tooth. This is the seventh tooth from the front of the mouth. It has 
 a crown, neck and three roots. 
 
 The coronal portion of the tooth is smaller, less quadrilateral in out- 
 line, and its usual features more pronounced than the former; thus 
 the buccal cusps are separated by deeper sulci and hence appear to be 
 more pronounced than in the first molar. 
 
 The buccal surface is flattened from above downward and slightly 
 convex from side to side. Often crossed by a broad horizontal depres- 
 sion, it is fairly quadrangular in outline, its longest border being the 
 inferior which, like that of the first molar, is divided by a fissure into 
 two uneven parts, and is doubly curved on account of the elevations 
 of the buccal cusps. 
 
 The most noticeable feature on the lingual side is the marked sloping 
 
DESCRIPTIVE GROSS ANATOMY 
 
 37 
 
 of the distal part and the very sHght elevation of the line of the lower 
 border. It is thus dissimilar to what obtains in the first molar. 
 
 The mesial surface is considerably broader in its bucco-lingual 
 diameter than its height. It is slightly convex and shelves off tow^ard 
 the inner side. 
 
 The distal surface is extremely convex in both directions and short 
 in the superior and inferior diameter. In both cases the upper border, 
 represented by the neck, is practically a straight line, while the lower 
 border is very diversified in this respect, particularly on the distal side. 
 
 Differing in a remarkable degree from that of the first molar, the 
 morsal surface of this tooth presents usually the four cusps of the typi- 
 cal molar, but in many instances three cusps only are seen, viz., antero- 
 external, postero-external and internal. When four are present they 
 are the homologues of those of the first molar. The large antero- 
 internal cusp is united with the postero-internal by an inconspicuous 
 oblique ridge, which is commonly traversed by a shallow sulcus. The 
 two outer cusps exhibit the usual mammilliform shapes of a typical 
 molar. They are separated by a deep fissure which ends at a point 
 near the center of the buccal surface. The antero-internal cusp is 
 frequently fused to the postero-internal cusp, the two forming a large 
 irregular eminence with pointed extremity and sloping sides. A 
 vertical depression, amounting sometimes to a fossa or pit, may here 
 be seen. 
 
 A B C D 
 
 Fig. 9. — Maxillary second molar. A, buccal surface; B, mesial surface; C, distal surface; 
 
 D, bucco-lingual section. 
 
 The neck lies in a horizontal plane and probably, when compared 
 with that of the first molar is somewhat more constricted. 
 
 The Roots. — ^The divergency of the three roots of the first molar 
 are not so marked in this tooth. Of smaller build, there is a tendency 
 for their union, especially of the palatine and the anterior buccal. 
 Obliquity of the crown frequently obtains, with consequent obliquity 
 of the roots. Deflection backward of all three is quite common. 
 
 Pulp Cavity. — ^The coronal part is broad in the bucco-palatine direc- 
 tion, narrow in the other. The floor of the cavity is fiat or depressed. 
 The root canals are exceedingly fiattened from side to side. 
 
38 ANATOMY OF THE TEETH OF MAN 
 
 Calcification commences at the fifth year, being completed between 
 the sixteenth and eighteenth. The tooth begins to erupt about 
 the end of the eleventh year. 
 
 Length, 22 mm.; width, 11 mm. 
 
 Identification, as in the first molar. 
 
 Occlusion. — ^The mesio-buccal cusp occludes with the central part 
 of the morsal surface of the mandibular second molar and the disto- 
 buccal cusp with both the distal cusps of the second molar and the 
 mesial cusps of the third molar. 
 
 The Third Molar. — ^More variations in size, shape, position and 
 anatomic features of the crown and roots exist in this than in any 
 other member of the dental series. Frequently suppressed it is the 
 smallest of the three molars and totally dissimilar in pattern to the 
 first molar. The crown presents five surfaces for examination. 
 
 Buccally there is a close resemblance to the corresponding surface 
 of the second and first molars. It is, however, more convex in both 
 directions, particularly from side to side; less extensive in the mesio- 
 distal diameter and its lower border less distinctive and more rounded. 
 A vertical shallow groove divides it into two unequal parts, of which 
 the anterior is the greater. The upper border is flat, the angles round, 
 especially that on the disto-buccal side. 
 
 On the lingual side the tendency to a shelving or sloping of the distal 
 portion, noticed in the middle molar, is much more accentuated here. 
 The whole surface is slightly convex from above downward, but later- 
 ally this convexity is greatly pronounced. 
 
 The mesial surface is broad and flat, and when the tooth is in situ 
 is close up against the distal surface of the second molar, thus con- 
 siderably reducing the capacity of the interproximate space. 
 
 Distally the crown is markedly convex, narrower from above down- 
 ward than in a lateral direction. 
 
 The morsal surface of the crown, on comparison with the other molars 
 is smaU, quadricuspid in about 50 per cent, of cases, and tricuspid 
 in about 50 per cent, of cases, and notable in the absence of any 
 deep sulci, fissures or elevated cusps. In the tricuspid form the internal 
 cusp is the largest, the postero-external the smallest. The crown is 
 frequently divided into seven or eight tubercles, each separated by 
 short, shallow and wide grooves; each also passing in every direction 
 from a short, central, deep sulcus running across the antero-posterior 
 diameter of the tooth. 
 
 The neck is more constricted on the distal than the mesial surface. 
 It lies in a horizontal plane. 
 
 Possessing normally three roots, which may be separate and some- 
 what divergent, or confluent, as usually happens — roots which are 
 
DESCRIPTIVE GROSS ANATOMY 
 
 39 
 
 short, small, deflected backward— this tooth may exhibit at times 
 four, five or six roots. The obliquity of the crown in these conditions 
 is repeated in the obliquity of the roots, which are often misshapen and 
 tortuous, the palatal root or roots being the most inconspicuous of all. 
 
 Fig. 10. — -Maxillary third molar. 
 
 B CD 
 
 A, buccal surface; B, palatal surface; C, mesial surface; 
 D, distal surface. 
 
 Triangular in outline and in shape the pulp cavity varies just as 
 much as the pattern of the crown. When triangular in outline the 
 buccal wall is the shortest; its " infundibulum" or base is absent; the 
 orifices of the root canals close together and exceedingly minute. 
 
 Calcification begins dm-ing the ninth year, is completed between the 
 eighteenth and twentieth years and the tooth begins to erupt at about 
 the eighteenth to twentieth year. 
 
 Length, 20 mm.; width, 11 mm. 
 
 Identification. — Can be effected by placing the tooth in the position 
 described for the first molar, when the flattened mesial surface of the 
 crown will point to the side to which the tooth belongs. 
 
 Occlusion. — In this the only tooth of the maxillary series occluding 
 with one mandibular tooth, the large central sulcus accommodates 
 the external and distal cusps and thus slightly overlaps the tooth on 
 the buccal as well as the distal side. 
 
 2. The Mandibular Teeth. — ^The First Incisor. — Situated on either 
 side of the alveolar process of the mandible at the symphysis menti, 
 which, in the junction of the two halves of the bone, as a rule, leaves 
 no traces in fully-formed conditions, this tooth is the homologue of the 
 first mandibular incisor in anthropoid apes and is the corresponding 
 tooth in occlusion with its maxillary namesake. It is probably less 
 variable in pattern and situation than any other tooth, and in the 
 absence of a tendency to formation of a cingulum, differs thus very 
 markedly from its congener in the upper jaw. It possesses a crown, 
 neck, root and pulp cavity. 
 
 The crown is well proportioned. Fashioned like a fiattened cone and 
 thus chisel-shaped, smooth with, at times, obvious imbrication lines 
 on the triangular labial side, it is more convex from above downward 
 
40 
 
 ANATOMY OF THE TEETH OF MAN 
 
 than from side to side, being devoid of a perpendicular groove. It is 
 broad at its superior or incisive edge, which at birth is often sur- 
 mounted by three tubercles, as in the maxillary teeth, and rapidly 
 narrows as it approaches the very inconspicuous inferior or gingival 
 border. 
 
 The lingval surface is concave in both directions, that from side to 
 side being particularly noticeable. The triangular proportions of the 
 labial surface appear here, but are more accentuated on account of the 
 somewhat greater elevation of the sides of the triangle, particularly at 
 its apex. This surface is nearly always free from depressions or grooves. 
 
 Mesially, a flat triangular surface, with its indistinguishable base 
 below at the gingival margin, and its apex at the mesial angle of the 
 incisive edge, it exhibits generally the same features on th.e distal 
 aspect of the crown, which, however, may be slightly concave in the 
 vertical and a little convex in the transverse direction. The mesial 
 surface is slightly larger than that on the opposite side. 
 
 The borders and angles are similar to those described in connection 
 with the maxillary tooth. 
 
 The neck is slightly constricted and therefore inconspicuous. It is 
 curved downward on the labial and lingual sides. 
 
 The root is long, narrow in the antero-posterior diameter, but broad 
 and flattened in the other direction. Its anterior side is slightly longer, 
 less convex, and broader than the other. The flattening of the sides 
 may amount at times to a shallow grooving extending nearly all the 
 length of the distal aspect of the root. 
 
 A B CD 
 
 Fig. 11. — Mandibular first incisor. A, labial surface; B, lingual surface; C, mesial 
 
 surface; D, mesio-distal section. 
 
 The outline of the pulf cavity follows that of the external portion of 
 the tooth, being quite narrow from side to side, and broad in labio- 
 lingual section. The root canal may be bifurcated, but this is not a 
 usual condition. 
 
 Calcification of this tooth begins diu-ing the first twelve months after 
 birth, and the apical foramen is formed by the tenth year. In 30 per 
 cent, of cases the tooth is erupted about the sixth year and sixth month. 
 
DESCRIPTIVE GROSS ANATOMY 
 
 41 
 
 Extreme length, 23 mm.; extreme width, 6 mm. 
 
 Identification. — In a horizontal position, with root toward the 
 observer, the longer side of the tooth indicates the side which it occu- 
 pies when in situ. 
 
 Occlusion occm-s on the labial side with the lingual aspect of the crown 
 of the maxillary first incisor. 
 
 The Second Incisor. — ^A reversal of the anatomic characteristics 
 of the upper incisor is found here in the fact that while the maxillary 
 second incisor is considerably smaller than the first incisor the mandib- 
 ular second incisor is larger than that just described. In some jaws 
 there is great disparity in size, but in well-constructed typical instances 
 difl^erences in the dimensions of the two are not so marked. 
 
 Crown. — ^Triangular in outline, the labial surface is broad at the base 
 and incisive edge and narrow at the gingival margin, but the angles 
 are not so acute as in the first incisor. The surface is a little more 
 convex in both directions than that tooth. It has a long upper border. 
 
 Lingually the surface is the counterpart of the first incisor. In some 
 cases the concavities are slightly more pronounced. There is no 
 attempt at the formation of an internal cusp, as in the upper tooth, 
 consequently no pits or fissures are here observed. 
 
 The mesial surface is long and either flattened or slightly concave. 
 Its superficies is trangular, with the base below and apex above, form- 
 ing with the incisive edge an acute angle. 
 
 A B C D 
 
 Fig. 12. — ^Mandibular second incisor. A, labial surface; B, lingual siu-face; C, mesio- 
 distal section; D, labio-lingual section. 
 
 Bistally the surface is short, flat, or slightly concave, and its angle 
 at the incisive edge nearly a right angle. 
 
 The Neck. — ^The coronal and radicular portions blend imperceptibly 
 into one another and the junction of the two usually cannot be seen 
 except on the lingual side. 
 
 The root is longer in this than in the preceding tooth. It is straight, 
 narrow from before backward, and broad from side to side. A median 
 
42 ANATOMY OF THE TEETH OF MAN 
 
 vertical groove often extends down its entire length on both sides, and 
 is generally more marked on the side toward the canine. 
 
 The pulp cavity resembles that of the first incisor, being extremely 
 flattened about the midportion of the root, but cylindrical in the 
 coronal and apical regions. In its coronal parts it extends somewhat 
 suddenly to form a not inconsiderable-sized cavity. 
 
 Calcification, root formation and eruption occur at the ages of the 
 first year, tenth to twelfth, and seven and a half years respectively. 
 
 Length, 24.5 mm.; width, 6 mm. 
 
 Identification as in the mandibular first incisor. 
 
 Occlusion takes place with the lingual aspect of the crowns of the 
 maxillary first and second incisors. 
 
 The Canine. — ^This tooth affords a good example of the transitional 
 type of organ from the chisel-like incisive crown of the anterior teeth 
 to the semi-molariform pattern of the posterior teeth. The intermediate 
 character of the coronal features here is justly noticeable. Occasion- 
 ally it may be an enormous tooth, especially in length. In tj^pical 
 specimens the buccal aspect of its crown has a greater superficies than 
 any other mandibular tooth. 
 
 Crown. — On its buccal side the crown presents an extensive surface 
 for examination. A vertical parallelogram, its upper border is pointed, 
 the apex being nearer the front than the back, thus dividing the incisive 
 edge into two unequal parts, of which the posterior may measure twice 
 the length of the anterior. The surface is convex in both directions, 
 more in the vertical than in the horizontal. A slight perpendicular 
 ridge of enamel may frequently be found here. The lower border is 
 in a straight line. 
 
 On the lingual surface a large, shallow concavity appears. This is 
 deeper from side to side than above downward. The floor of the 
 cavity is not smooth but overrun sometimes by one or more vertical 
 ridges, separated by grooves of varying depth and length. The borders 
 of this surface are much rounded, especially at their lower part, where 
 an elevation of the cingulum may occasionally be seen. A canine with 
 a lingual cusp always belongs to the upper, never to the lower jaw. 
 
 The mesial surface is triangular in outline, being similar in shape and 
 size to the distal surface of the second incisor. It is flat and extensive 
 and passes imperceptibly over to the root by means of an inconspicuous 
 neck. 
 
 The distal surface differs in a marked degree from that last described, 
 in that its surface is convex in both directions, particularly the vertical, 
 and joins with the sloping upper border of the crown to make a 
 prominent "contact point" with the neighboring tooth. It bends in 
 very suddenly toward the constricted neck, and thus is produced one 
 side of an unusually large interproximate space. 
 
DESCRIPTIVE GROSS ANATOMY 
 
 43 
 
 The most conspicuous part of the neck is on the labial and lingual 
 surfaces. 
 
 The root assumes great dimensions. It is broad at the cervical margin, 
 is usually straight, i. e., has the same longitudinal axis as the whole 
 of the tooth, but in every instance is inclined to be deflected somewhat 
 toward the distal side. Shallow grooves exist mesially and distally. 
 Of the four aspects of the root the lingual and the mesial are the 
 narrower. Bifurcation of the root canal is fairly common, and the 
 development of an extra lingual root not infrequent. 
 
 The pulp cavity bears some resemblance in shape to that of the 
 maxillary canine. It is large in the labio-lingual diameter, narrow and 
 tube-like in the mesio-distal section. 
 
 A B CD 
 
 Fig. 13. — Mandibtdar canine. A, labial surface; B, lingual surface; C, mesio-distal 
 section; D, labio-lingual section. 
 
 Calcification begins with the third year, is concluded at about the 
 twelfth or thirteenth, and the tooth begins to erupt in company with 
 its maxillary confrere before calcification is complete, about the eleventh 
 year and third month. 
 
 Length, 31 mm.; width, 12 mm. 
 
 Identification. — ^Placed horizontally, with root toward the observer, 
 the shorter of the two portions of the cutting edge is directed toward 
 the side to which the tooth belongs. 
 
 In occlusion the labial surface is in contact with the lingual surface 
 of the maxillary canine, and also of the distal portion of the same 
 surface of the second incisor. 
 
 The First Premolar. — Most interesting of all teeth from a mor- 
 phological point of view, this tooth, even better than the preceding, 
 exhibits and illustrates a gradational type between a tooth, with a 
 thin, incisive edge and that with a broad morsal surface. Though 
 there are no two teeth absolutely alike in shape and pattern, there is 
 generally a close similarity in the design of the corresponding teeth in 
 each half of the jaw. A variation exists here, for the two first pre- 
 
44 ANATOMY OF THE TEETH OF MAN' 
 
 molars may be entirely different, one presenting a crown like an under- 
 developed canine, the other molariform in general appearance. 
 
 The typical crown imitates the architectural features of the maxillary 
 canine, as will be described below. 
 
 Externally the buccal coronal surface closely resembles that of the 
 anterior tooth. It is less high, however, and approaches a pentagonal 
 form with a pointed upper extremity. It is markedly convex from side 
 to side; less so in the other direction. Its upper border is like that of 
 the canine. 
 
 The lingual surface is very inconspicuous. It is convex from before 
 backward, less so from above downward. It is four times as long as it 
 is broad, and surmounted by a tubercle which extends over the coronal 
 surface. 
 
 The mesial convex surface is more extensive than the opposite, 
 sloping obliquely inward from its junction with the buccal surface. 
 
 The area of the distal surface is much smaller than that on the mesial 
 side, due to the encroachment of the backward slope of the morsal 
 surface of the tooth. 
 
 Morsally, a unique appearance is presented by the absence or sup- 
 pression of the internal cusp, so conspicuous in the maxillary premolar. 
 That the internal cingulum is raised on this surface is obvious, for 
 frequently not only does it form a thickened tubercle, but a marked 
 ridge, which passes immediately upward to terminate in the apex of 
 the incisive edge, and is derived from the same elevated crest. Fur- 
 ther, from the base of this ridge also, frequently short thick bands 
 elevate themselves upward and forward and upward and backward. 
 The consequence of the production of these ridges is the formation of 
 deep pits on the mesial and distal aspects of the crown. Of these 
 the latter is the deeper. This triangular surface may exhibit four or 
 five tubercles, or two cusps, one prominent, the other less pronounced. 
 
 The neck occupies a horizontal plane. It is frequently almost 
 invisible, owing to its lack of constriction. 
 
 On the faces of the root, which follows with but little deviation the 
 line of the central longitudinal axis of the tooth itself, the broader 
 are on the buccal and mesial sides. Grooves existing on the mesial 
 and distal sides may be deepened to such an extent as to give the 
 appearance of the bifurcation or the production of a third root. In 
 the case of the latter the root is placed in an antero-external position. 
 
 The pulp cavity simulates in outline the general contour of the crown. 
 A small cornu may insinuate itself toward the lingual tubercle. Usually 
 the pulp chamber is a slightly flattened cylinder. In the case of an 
 additional root or roots the canals are cylindrical. 
 
DESCRIPTIVE GROSS ANATOMY 
 
 45 
 
 Calcification begins about the fourth year. The apical foramen is 
 completed at the eleventh to the twelfth year, eruption taking place 
 at the ninth year and tenth month. 
 
 Length, 25 mm.; width, 7 mm. 
 
 Identification. — In a vertical position, with the extremely rounded 
 labial surface of the crown nearest the observer, the round mesial 
 surface, with its fossa, points to the side to which the tooth belongs. 
 
 Occlusion. The mesial and coronal surfaces interdigitate with the 
 distal aspect of the crowns of the maxillary canine and its distal 
 surfaces with the inner cusp of the maxillary first premolar. 
 
 A B c D 
 
 Fig. 14. — Mandibular first premolar. A, buccal surface; B, lingual surface; C, distal 
 surface; D, labio-lingual section. 
 
 The Second Peemolae. — ^The main architectural features of this 
 tooth are entirely different from those just described. It approxi- 
 mates more closely that of the upper second premolar, save that in 
 typical specimens it is smaller in every particular. The crown is large, 
 with rounded angles, and its inner portion raised more nearly on a 
 level with the occlusal surface of the first molar than in the anterior 
 tooth. 
 
 The croum possesses five surfaces. Of these the buccal is the largest, 
 being almost identical in shape, size and contour with that of the first 
 premolar. It may measure a little less in the vertical direction. The 
 cusp is round. 
 
 Lingually — a fairly convex surface — the crown is wider from before 
 backward than from above downward, and thus presents the outlines 
 of a flat parellelogram. 
 
 Of the mesial and distal surfaces the former is larger, smoother and 
 more flattened than the latter, the presence of a cusp at the upper 
 part of the latter giving it an undue prominence over that of the 
 other side. 
 
 The morsal surface is somewhat square in outline; all of its four 
 borders are rounded, its cusps and tubercles less marked than those of 
 the upper tooth. The sulcus is fairly deep, runs from before backward, 
 and divides behind into two and sometimes three branches, enclosing 
 
46 
 
 ANATOMY OF THE TEETH OF MAN 
 
 elevations of enamel which, not being pronounced enough to designate 
 as cusps, are more correctly described as tubercles. The largest of 
 these is often placed most distally. 
 
 The neck is but slightly discernible on its convex distal side. It lies 
 in a horizontal plane. 
 
 The root is unusually long and large. Its buccal side is wider than 
 the opposite and its anterior aspect flat or slightly convex, its distal 
 surface concave or grooved. 
 
 The pulp cavity possesses two marked cornua, of which the larger 
 is contained in the labial cusp. The pulp canal is single and much 
 flattened from side to side. 
 
 I' 
 
 A BCD 
 
 Fig. 15. — Mandibular second premolar. A, buccal surface; B, mesial surface; C, mesio- 
 
 distal section; D, bucco-lingual section. 
 
 Calcification begins between the fourth and fifth years, is com- 
 pleted seven years later, and the tooth erupts at a date prior to its 
 completion, namely, about the tenth year and sixth month. 
 
 Length, 23 mm.; width, 8 mm. 
 
 Identification. — ^It is generally almost impossible to determine 
 whether the second premolar belongs to the right or the left side of 
 the mandible. 
 
 Occlusion. — ^This tooth occludes with the maxillary premolars, its 
 mesial coronal surfaces coming into contact with the distal surfaces of 
 the upper first premolar and its distal surfaces with the mesial aspects 
 of the crown of the second premolar. 
 
 The First Molar. — ^Upon this tooth the dentition of man probably 
 is principally dependent for the greatest stress and strain in the dental 
 arch, its position in the middle of the masticatory field giving it an 
 importance which is second only to that of its maxillary homologue. 
 It possesses a considerable degree of anatomical interest also, for its 
 morsal surface presents for examination a larger and more compli- 
 cated arrangement of parts than obtains in any other tooth. Its 
 relations to the sciences of palaeontology, anthropology and biology, 
 in addition to those of surgery and orthodontics, invest it with a degree 
 of interest which is unique. The obliquity which is so common a 
 
DESCRIPTIVE GROSS ANATOMY 
 
 •47 
 
 feature of the crown of the maxillary molar is here noticeable; the 
 tooth is therefore more or less variable in form. 
 
 A crown, neck and two roots are to be described. 
 
 The crown has five surfaces: mesial, distal, buccal, lingual and morsal. 
 
 The mesial surface is smooth and equally convex in both directions. 
 It has a curious outline, roughly similar to that of an isosceles triangle 
 with an extended base and considerably flattened apex, of which the 
 outer straight line bends inw^ard rather more than the opposite, making 
 a more acute angle at its junction with the base than the internal, which 
 contains almost a right angle. Its upper surface is marked by the 
 presence of two shorter and smaller apices — the anterior portions of the 
 antero-external and antero-internal cusps. The "contact point" of 
 this surface is to the outer side of the midline and about midway 
 between the neck and the upper border. 
 
 Distally the siu-face is fairly quadrangular in outline, broader in 
 the bucco-lingual diameter, and relieved by the elevation of the distal 
 surface of the fifth or distal cusp. Thus the upper border presents 
 three elevations of varying size, of which the most distal is the shortest 
 and most conspicuous. 
 
 A B c D 
 
 Fig. 16. — Mandibular first molar. A, buccal surface; B, lingual surface; C, mesial 
 
 surface; D, distal surface. 
 
 Of all the buccal surfaces of the teeth, that of this tooth is by far the 
 largest. It frequently measures 12 mm. from before backw^ard, approxi- 
 mately about 3 mm. longer than that w^hich obtains in the upper 
 tooth. It is exceedingly convex, from above downward, giving the 
 appearance of being inclined inward, less convex from side to side. 
 In outline it assumes the form of a rough parallelogram, wdth a flat, 
 straight base and somewhat divergent sides, and an indented upper 
 border raised into three points, of which the anterior is broad and round, 
 the middle sharp and the posterior small and blunt. A groove passes 
 between the two first named and frequently terminates in a con- 
 spicuous pit, a favorite site for dental caries. 
 
 The lingual surface resembles somewhat remarkably the buccal 
 
48 ANATOMY OF THE TEETH OF MAN 
 
 surfaces of the maxillary first and second molars, the points in the 
 upper border, however, being sharper than the rounder elevations 
 in the last named. Its smooth, slightly convex area is contained 
 in a fairly regular parallelogram, of which the upper and lower sides 
 are the longer. A pit or fossa is seldom, if ever, noticeable on this 
 surface. 
 
 Morsally this tooth presents a trapezoidal figure with five cusps 
 and five fissures. Of all the sides the anterior is the most nearly 
 straight, the distal the most acute, the innermost the longest and 
 the outermost divided into two even parts. The cusps are named 
 according to their position: (i) Antero-external or mesio-buccal; (ii) 
 antero-internal or mesio-lingual ; (iii) postero-external or disto-buccal ; 
 (iv) postero-internal or disto-lingual; (v) distal. The chief character- 
 istics of the individual cusps are as follows: mesio-buccal, the largest, 
 most rounded, with shelving outer part; mesio-lingual, the most 
 acutely pointed; disto-buccal, narrow from front to back, somewhat 
 wedge-shaped, with blunt apex; disto-lingual, short, triangular, fre- 
 quently subdivided into three small tubercles by two short grooves- 
 passing inward; and distal, small, prismatic in outline and possessing 
 an acute cusp. 
 
 The fissures vary greatly in depth, direction and dimensions. As 
 they are situated, so are they named. Thus, taking their origin from 
 the center of the crown the anterior separates the two mesial cusps, and 
 as it reaches its termination often bifurcates widely and so produces 
 an extra cusp, which is then named the mesial cusp; the j)osterior 
 running irregularly backward and enclosing in its bifurcation the 
 distal cusp; the buccal passing directly outward, separating the two 
 buccal cusps and extending over the ridge to the pit on the buccal 
 side; and the lingual, separating the two inner cusps and terminating 
 just short of the upper border of the lingual surface. The short fifth 
 fissure is centrally placed and unites the others together. 
 
 The neck is usually indistinct, quadrangular in outline and in the same 
 horizontal plane. 
 
 The roots are two in number: anterior or mesial, and posterior or 
 distal. The former is broad, extremely flattened from before backward, 
 slightly deflected backward, somewhat triangular in shape^ and grooved 
 on both sides, that on the distal side being the more pronounced; the 
 latter is smaller, more nearly straight, narrower and grooved on its 
 anterior aspect. 
 
 The pulp cavity is irregularly square in its coronal portion, with 
 extensive cornu at its upper corners. There is no cornua, as a rule, 
 beneath the distal cusp. Three pulp canals are frequently found, two 
 in the mesial root and one in the distal. Of these the former are small, 
 
DESCRIPTIVE GROSS ANATOMY 49 
 
 flattened laterally; the latter large and much flattened from side to 
 side. 
 
 Calcification begins during the eighth month of intra-uterine life. 
 The roots are completely formed by the ninth to the tenth years, and 
 eruption takes place at the sixth year and sixth month. 
 
 Length, 21 mm.; width, 12 mm. 
 
 Identification can be efl^ected by holding the tooth crown uppermost, 
 with the small triangular distal cusp away from the observer, the pit 
 on the buccal surface (or the very rounded character of the latter if 
 there is no pit) points to the side opposite to that to which the tooth 
 belongs. 
 
 Occlusion. — ^The mesio-buccal cusp occludes with the distal ridges of 
 both cusps of the maxillary second premolar, and the mesio-buccal and 
 mesio-lingual cusps of the maxillary first molar; and its disto-buccal 
 cusp with the central part of the morsal surface of the same tooth. 
 
 The Second Molar. — ^This tooth is modeled on a different archi- 
 tectural plan from that of the preceding. It differs in the facts that it 
 is smaller, more sjinmetrical in shape, its cusps more proportionally 
 equal in size. It has no fifth cusp and its roots are closer together 
 than in the first molar. 
 
 The croicn has five surfaces. Mesially the surface is slightly convex, 
 square in outline, with its superior border raised into two blunt points, 
 the sides of the mesial cusps. The lower border slopes gently downward 
 and outward. On the distal side a greater convexity of the surface is 
 observed over any other. Its upper border is nearly horizontal, being 
 relieved somewhat by the presence of two blmit apices. With the 
 exception of the superior surface the bnccal aspect of the crown is the 
 largest of all. Quadrangular in outline, its anterior and posterior 
 borders are more nearly parallel than in the first molar. It is smooth 
 and convex in both directions, especially the vertical. It is seldom 
 disfigured by the presence of a pit or fossa. The lingual surface is 
 broader antero-posteriorly than vertically. Slightly convex, it presents 
 a similar appearance to that of the opposite side. The occlusal surface 
 is remarkable for the regular arrangement of its constituent parts. 
 Its four cusps, mesio-buccal or antero-external, disto-buccal or postero- 
 external, mesio-lingual or antero-internal, and disto-lingual or postero- 
 internal, are distinctly uniform in character, outline, size, shape and 
 height. If there is a difference the mesio-buccal cusp is the most impor- 
 tant and pronounced. The fissiu-es emanate from a common central 
 spot in the middle of the crown. They vary slightly in depth, run in 
 straight lines, pass directly forward (mesial fissure) , backward (distal) , 
 outward (buccal), and inward (lingual) and seldom bifiu^cate or extend 
 over the sides of the crown. 
 4 
 
50 
 
 ANATOMY OF THE TEETH OF MAN 
 
 The constriction of the horizontally placed neck is unusually marked. 
 
 Similarly to the first molar there are two roots. Generally speaking 
 they are smaller, more confluent and less compressed from side to side 
 than those of the aforementioned tooth. The mesial is the larger and 
 broader and deflected somewhat backward; the distal, the straighter 
 and frequently the shorter and narrower. The distal root is not grooved. 
 
 The pulj) cavity follows in shape the general outline of the crown; the 
 root canals, of the roots, that on the mesial side being much flattened 
 laterally, the other more nearly cylindrical. 
 
 ^ 
 
 4^ 
 
 "w 
 
 } 
 
 ABC D 
 
 Fig. 17. — Mandibular second molar. A, buccal surface; B, lingual surface; C, mesial 
 surface; D, mesio-distal section. 
 
 Calcificatio7i occupies about eleven or twelve years, the first signs 
 appearing at the fifth year and the apical foramina completed by the 
 sixteenth or seventeenth year. Eruption begins about the eleventh 
 year. 
 
 Length, 23 mm.; width, 11 mm. 
 
 Identification. — ^A typical tooth has, as already indicated, a square 
 crown. If such a tooth is held crown uppermost, with the larger root 
 nearest the observer, the flatter of the two lateral surfaces will point 
 to the side to which the tooth belongs. 
 
 Occlusion. — ^The mesio-buccal cusp occludes with the disto-buccal 
 and disto-lingual cusps of the maxillary first molar, and the mesio-buccal 
 and mesio-lingual cusps of the second molar. Its disto-lingual cusp 
 interdigitates with the central part of the morsal surface of the maxil- 
 lary second molar. 
 
 The Third Molar. — Typical examples of this tooth are difficult to 
 find. It undergoes, however, fewer variations in size and pattern of 
 crown and shape of roots than its maxillary congener. In a well-devel- 
 oped jaw it is a large tooth; even in a small jaw it is still a relatively 
 large tooth. While not subject to much change in architectural details 
 it is frequently misplaced, and its surgical affections most important 
 in their induction of severe systemic and general disturbances. 
 
 The crown occupies nearly the upper half of the entire superficies. 
 This is more noticeable, perhaps, on its distal than on its mesial side. 
 
DESCRIPTIVE GROSS ANATOMY 
 
 51 
 
 The mesial surface is convex, slopes inward and is higher on the 
 internal than on the buccal side. The upper border is raised into two 
 more or less definite projections or points. 
 
 DistaUy the surface is markedly convex. The amelo-cemental junc- 
 tion at the neck is fully constricted. This surface is fairly square in 
 outline, and its upper border relieved by three or more blunt, variable 
 points. 
 
 A BCD 
 
 Fig. 18. — Mandibular third molar. A, buccal surface; B, lingual surface; C, mesial 
 
 surface; D, distal surface. 
 
 The buccal surface is much broader than deep. It is very convex, 
 particularly behind, where its distal angle is considerably rounded. 
 The lingual surface is broad from before backward, shallow from above 
 downward, the line of its upper border being deeply indented in the 
 center. 
 
 The occlusal surface presents many varieties of shape, outline, size 
 and pattern. It may be rounded or flattened, arched or tuberculate; 
 it may be roughly hexagonal; it may be broader antero-posteriorly 
 than bucco-lingually; it may have four, five, six, seven or eight cusps 
 of every different shape and size. It may closely simulate the pattern 
 of its neighbor; it may be entire dissimilar, presenting superficial pits, 
 grooves, fissures, fossse and the like. The table-land may be raised up 
 into one large cusp toward the lingual side of this surface with, at its 
 base, numerous tubercles, which sometimes are conical, oval, oblong, 
 round or pointed. Well-formed teeth exhibit fissiues which run in 
 similar directions to those of the second molar, but are generally shal- 
 lower and less regular in general character. 
 
 The cervical margin is well marked and nearly horizontal. 
 
 The roots are diminutive and disproportionate to the size of the 
 crown; inclined somewhat backward; usually confluent; occasionally 
 separate and in rare instances allowing the passage of the mandibular 
 nerve between them. Usually two are present, but there may be three 
 or even four, all of which rapidly taper down at their apices to a fine 
 point. 
 
 The shape of the common 'pulp cavity is governed by that of the 
 
52 
 
 ANATOMY OF THE TEETH OF MAN 
 
 crown. The canals are small and irregular, depending upon the general 
 shape and character of the roots themselves. 
 
 Fig. 19. — ^Vertical section through the left maxilla and mandible of man, with the 
 external alveolar plates removed, to show the general arrangement of the roots of the 
 teeth in situ, and the shapes, sizes and positions of their pulp cavities and root canals. 
 
 ■■ 
 
 i 
 
 ^^ 
 
 [■ 
 
 H^^i 
 
 r 
 
 ^ 
 
 ^■^H 
 
 ^m f^^Mii 
 
 
 ^^ 
 
 ^^^H^l 
 
 
 a» 
 
 1 
 
 I^^^^H 
 
 1 ^ flH 
 
 
 • 
 
 ^^^^^^^1 
 
 ix:' wm 
 
 ' -r 
 
 
 ^^^1 
 
 r »■>« • ^^H 
 
 
 
 ^^^^^H 
 
 '' "" ^1 
 
 » 
 
 
 ^^H 
 
 "f JHaj 
 
 
 
 .: ^ 
 
 
 
 1 
 
 m 
 
 ■i 
 
 
 If 
 
 ifll 
 
 A B 
 
 Fig. 20. — Horizontal sections through the alveolar process of the right maxilla of 
 man with the permanent teeth m situ at (A) the gingival margins, at (B) the root por- 
 tions, showing the shapes, sizes and positions of the pulp cavities and root canals. 
 
DESCRIPTIVE GROSS ANATOMY 
 
 53 
 
 A B 
 
 Fig. 21. — Horizontal sections through the alveolar process of right half of mandible 
 of man with the teeth in situ at {A) the gingival margins, at {B) the root portions, show- 
 ing the shapes, sizes and positions of the pulp cavities and root canals. 
 
 Fig. 22. — The occlusal surfaces of the permanent teeth in situ. The dental arch is 
 elliptical in shape in the maxilla, and parabolic in the mandible — a condition which 
 obtains in 70 per cent, of cases. 
 
54 ANATOMY OF THE TEETH OF MAN 
 
 Length, 16 mm.; width, 10 mm. 
 
 Identification. — ^Typical specimens may be identified as in the case of 
 the second molar, but it most frequently happens that it is impossible 
 to determine to which side of the mouth the tooth belongs. 
 
 Calcification commences between the eighth and ninth year and 
 continues until the eighteenth to the twentieth year. Eruption takes 
 place during any period between the twentieth and twenty-fifth years. 
 
 Occlusion. — The mesial cusps occlude with the ridges of the distal 
 cusps of the maxillary second molar and the remainder of its morsal 
 surface with the anterior half of the maxillary third molar. 
 
 B. The Deciduous Series. — It is unnecessary, in the author's judg- 
 ment, to describe in detail in this article the anatomy of the deciduous 
 teeth. A few observations, however, are desirable to complete what 
 has already been written about the human dentition. 
 
 Ten in number in each jaw, the deciduous teeth represent on a smaller 
 scale somewhat closely the main architectural features of the permanent 
 dentition. They differ in the following particulars: their general 
 smallness; their rounded, short coronal surfaces; their great disparity 
 in size with one another, particularly in case of the second incisor and 
 second molar; the universal simplicity of their coronal patterns, and 
 unusually constricted necks, due, not to an elevation of the enamel but 
 to a curious outward bending of the dentin beneath. 
 
 The incisors are remarkable in that their labial and lingual surfaces 
 are broader from side to side than from above downward, those of the 
 first incisor being nearly twice the width of the other two. This is 
 particularly noticeable in the maxillary arch. The outermost incisors 
 are very conical in shape. The canines have broader crowns than the 
 incisors. The roots of the maxillary teeth are extremely long, measur- 
 ing nearly twice the length of those of the first incisors. The first 
 molars may frequently be mistaken for a small first premolar. All 
 molars possess five surfaces which correspond in name with those of the 
 permanent series. The crowns usually are smaller than those of the 
 second molars, but may on occasion be larger. Each possesses one 
 large inner cusp and the three small tubercles, or two cusps arranged 
 as a buccal ridge. The central sulcus is shallow and may bifurcate 
 toward the outer side. Its three roots are smaller than in the second 
 molar and widely divergent. 
 
 The crowns of the second molars possess four well-marked cusps, of 
 which the largest is either the antero-internal or the antero-external, 
 the oblique ridge being well developed and running in the same direc- 
 tion as in the permanent teeth. The mandibular second molar has 
 five cusps, three on the buccal and two on the lingual side, the 
 
RELATIONSHIPS 
 
 55 
 
 smallest usually being the postero-buccal. The two roots are short; 
 widely separated, fairly straight and laterally flattened. 
 
 The teeth vary in size^^ from 3.8 mm. in the mandibular first incisor 
 to 8.5 mm. in the second maxillary molar. 
 
 Fig. 23. — The occlusal surfaces of the deciduous teeth in situ. 
 
 Calcification occurs approximately as follows : The first and second 
 incisors about the fourth month of intra-uterine life; the canine and 
 first molar about the fifth, and the second molar about the fifth to the 
 sixth month. At birth calcification has proceeded to the extent of 
 the formation of half the crown of the first incisor, one-third of that 
 of the second incisor, one-sixth of that of the canine, the upper part 
 of that of the first molar and the cusps of the second molar. They 
 erupt in the following order: first incisor, second incisor, first molar, 
 canine and second molar and at the following approximate dates after 
 birth : first incisor from the sixth to tenth month, second incisor from 
 the eighth to twentieth month, canine fifteenth to the thirty-third 
 month, first molar twelfth to the twenty-sixth month and second molar 
 twenty-eighth to the thirtieth month. 
 
 VI. RELATIONSHIPS. 
 
 The Dental Arches. — In shape the upper is elliptical, the lower 
 assuming a parabolic curve. The maxillary teeth in normal occlusion 
 
56 
 
 ANATOMY OF THE TEETH OF MAN 
 
 slightly overlap the mandibular teeth. The curve of von Spee, pro- 
 duced by a sHght concavity in the plane of the occlusal surfaces of 
 
 Fig. 24. — Semi-elliptical maxillary and mandibular dental arches — a condition which 
 obtains in 20 per cent, of cases. 
 
 Fig. 25. — The divergent arch — a condition which obtains in 6 per cent, of cases. 
 
RELATIONSHIPS 
 
 57 
 
 the mandibular teeth and a corresponding convexity in that in the 
 maxillary organs, is not always present; it is probable that the 
 normal arrangement of the parts is for both occlusal surfaces to lie in 
 a horizontal plane. 
 
 The Vascular System. — ^The vascular system is derived from the in- 
 ternal maxillary artery. The anterior dental branch of the infra- 
 orbital division of the third or ultimate stage supplies the maxillary 
 incisors and canines, the posterior dental branch the premolars and 
 molars. 
 
 1 
 
 ■p 
 
 
 1 
 
 |H:^' 
 
 i^^^H^H 
 
 5 
 
 
 1 ' I^^^^^E 
 
 
 ^ 
 
 
 
 HJI^HJHy * 
 
 
 Phi 
 
 ■HHJJI^^^HhK^ >« 
 
 Fig. 26. — The hyperbolic arch — a condition which obtains in 4 per cent, of cases. 
 
 In the lower jaw the mandibular or inferior dental artery supplies all 
 the teeth, a special branch — the incisive — passing directly to the 
 incisors and canines. 
 
 The Nervous System. — ^The trigeminal or trifacial nerve — the largest 
 of the cranial nerves, sensory in its upper two divisions and sensory 
 and motor in its lower third division — endows the teeth with sensation. 
 The antero-suyerior dental nerve is distributed to the maxillary incisors 
 and canines, the middle dental to the premolars and the posterior 
 dental to the molars. 
 
 The mandibular or inferior dental nerve is in relation with the molars, 
 premolars and canines in its posterior part, while anteriorly it transmits 
 an incisive branch to the incisors. 
 
58 ANATOMY OF THE TEETH OF MAN 
 
 The Lymphatic System. — There is no direct connection between the 
 pulps of the teeth and the lymph nodes of face and neck, but the 
 afferent channels and vessels of the gingival tissues, in common with 
 those of the cheeks, lips and anterior part of the tongue, communi- 
 cate with four or five submaxillary nodes found in the submaxillary 
 triangle on the surface of the submaxillary gland. They all discharge 
 their streams into the superficial and deep cervical nodes which 
 accompany the external and internal jugular veins respectively. 
 
 BIBLIOGRAPHY. 
 
 1. Albrecht: "Bec-de-lifevre," Societe d'Anthropologie, Bruxelles, 1882. 
 
 2. Black, G. V.: "Descriptive Anatomy of the Human Teeth," 1902. 
 
 3. Black, G. V.: "A Work on Operative Dentistry," 1908, vol. i. 
 
 4. 5, 6 and 7. Bland-Sutton: "Tumors, Iryiocent and Malignant," 1906. 
 
 8. Bolk: "Die Ontogenie der Primatenzahne (Odontolog. Studien L), 1913. 
 
 9. Broomell and Fischelis: "Anatomy and Histology of the Mouth and Teeth," 
 1914. 
 
 10. Colyer, J. F.: "John Hunter and Odontology," 1913. 
 
 11. Cope: "TheTritubercular Molar in Human Dentition." Journal of Morphology, 
 1888. 
 
 12. Cryer: "The Internal Anatomy of the Face," 1916. 
 
 13. Dolamore: "The Relation of the Deciduous to the Permanent Dentition." 
 Royal Dental Hospital Gazette, 1908. 
 
 14. Forsyth Major: "On some Miocene Squirrels, with Remarks on the Dentition 
 and Calcification of the Sciurinse." Proc. Zoo]. Soc, London, 1893. 
 
 15. Gray: "Anatomy: Descriptive and Applied," edited by E. A. Spitzka, 1913. 
 
 16. 17. Hopewell-Smith: "The Normal and Histological Pathology of the Mouth," 
 1918. 
 
 18. Hopewell-Smith: "An Introduction to Dental Anatomy and Physiology," 1913. 
 
 19. James, W. W. and Pitts, A. T.: "Some Notes on the Dates of Eruption in Four 
 Thousand Eight Hundred and Fifty Children, Aged Under Twelve," Proc. Roy. Soc. 
 Med., 1912. 
 
 20. Kukenthal: "Zur Dentitionfrage," Anatom. Anzeiger, 1895. 
 
 21. Leche: Morph. Jahrbuch, 1892. Biblio-theca Zoologica, 1895. 
 
 22. Marett Tims: "Evolution of the Teeth in the Mammalia." Jour. Anat. and 
 Phys., 1903. 
 
 23. Osborn: "Evolution of the Mammalian Molars to and from the Tritubercular 
 Type." Amer. Naturalist, 1888. . 
 
 24. Piersol: "Human Anatomy," 1918. 
 
 25. Rose : ' ' Ueber die Enstehung und Formabanderungen der Menschlichen Molar en. 
 Anat. Anzeiger, 1892. 
 
 26. Tomes, C. S.: "A Manual of Dental Anatomy," seventh edit., 1914. 
 
 27. Virchow: "Retention, Heterotypie und Ueberzahl von Zahnen." Verhand. d. 
 Berliner anthrop. Gesellschaft, 1886. 
 
CHAPTER II. 
 
 DENTAL HISTOLOGY, WITH REFERENCE TO OPERATIVE 
 
 DENTISTRY.^ 
 
 By FREDERICK B. NOYES, B.A., D.D.S. 
 
 In the fifteen years or more that have elapsed since this chapter was 
 prepared for the third edition of this work, there have been important 
 additions to our knowledge of the structure of the teeth and their 
 supporting tissues. But more important even than these additions 
 and changes in our knowledge of the facts are the development in the 
 dental profession and the recognition of the relation of the mouth 
 conditions to general systemic conditions and the health of the indi- 
 vidual. This development has changed the interest in dental histology 
 from one field to another. 
 
 When the chapter was first written dental histology was being 
 studied chiefly in its relation to the technical procedures of operative 
 dentistry and we may say with fairness that the study of the structure 
 of the enamel with reference to dental caries and the preparation of 
 cavities was its most important phase. The study of the microscopic 
 structure of the enamel of the tooth crown greatly- improved the pre- 
 paration of cavities, increased facility and rapidity of operation and also 
 improved the resulting filling operations. The facts are just as impor- 
 tant as ever but to a great extent they have already made their imprint 
 upon dental practice. 
 
 Today the most important question before the dental profession, 
 and the one in which the medical profession is most interested, is the 
 fate of the pulpless tooth and the relation of pathologic condition of 
 the supporting tissues to the health of the organism as a whole. Dental 
 histology must be studied from this point of view, and when the facts, 
 so far as they are known, are reviewed from this standpoint, om- knowl- 
 edge is found to be deplorably inadequate and defective. The rational 
 solution of the relation of the pulpless tooth to the human organism 
 cannot be reached until our knowledge of structural facts has been 
 greatly extended. It is important, however, to review the facts as 
 
 1 In the preparation of this material I am indebted to Dr. G. V. Black for the use of 
 his large and valuable collection of microscopic slides, and for much advice and many 
 suggestions. 
 
 (59) 
 
60 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 they are now known with reference to these problems. They are not 
 new problems, but the focus is now centered upon them. 
 
 From the standpoint of comparative anatomy, the teeth are found 
 to be not a part of the osseous system, but appendages of the skin, 
 and are to be compared with such structures in the body as the nails 
 and the hair. The teeth are a part of the exo-skeleton, and their 
 relation to the bones of the endo-skeleton is entirely secondary, for 
 the purpose of strength, the bone growing up around the tooth to 
 support it. 
 
 If we examine the skin, of such an animal as the shark, we find the 
 entire surface covered with small calcified bodies which are really 
 small, simple, cone-shaped teeth. The mouth cavity is to be regarded, 
 
 Fig. 27. — Shark's skull (Lamna cornubica) , showing succession of teeth. 
 
 when viewed in the light of its development, as a part of the outside 
 surface of the body which has been enclosed by the development of 
 the neighboring parts, and the dermal scales or rudimentary teeth 
 which were found in the skin covering the arches which form the jaws 
 have undergone special development for the purposes of seizing and 
 masticating the food. In the simplest forms there is only a develop- 
 ment in size and shape of these scales, and they are supported only by 
 the connective tissue which underlies the skin. These teeth are easily 
 torn off in the attempt to hold a resisting prey, and, as in the shark, 
 they are constantly being replaced by new ones (Fig. 27). In the more 
 highly developed forms there is a growth of the bone of the arch 
 forming the jaw upward around the bases of these scale-like teeth, to 
 support them more firmly and render them more useful. 
 
DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 61 
 
 If we compare the structure of the hair with that of the tooth, we 
 find in the case of the hair a horny structure formed by epithehal cells 
 resting upon a papilla of connective tissue; in the case of the tooth, a 
 calcified structure formed by epithelial cells resting upon a papilla of 
 connective tissue which is also partially calcified. 
 
 The relation of the bones of the jaws to the teeth is entirely a 
 secondary and transient one. The bone grows up around the roots of 
 the teeth to support them, and is destroyed and removed with the loss 
 of the teeth or the cessation of their function. In this way the develop- 
 
 y^ >4i^ 
 
 Fig. 2S. — Changes in the mandible with age ; buccal and lingual view. 
 
 ment of the alveolar process takes place around the temporary teeth; 
 all of this bone surrounding their roots is absorbed and removed with 
 the loss of the temporary dentition, and a new alveolar process grows 
 up around the roots of the permanent teeth as they are formed. This 
 development of bone around the roots of the teeth leads to the changes 
 in the shape of the body of the lower jaw, increasing the thickness above 
 the mental foramen and the inferior dtental canal. When the teeth are 
 finally lost this bone is again removed and the body of the jaw reduced 
 in thickness from above downward (Fig. 28). These phenomena are of 
 importance in their bearing upon the causes and treatment of diseased 
 
62 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 Fig. 29. ^Ground section of a canine: E, enamel; Cm, cementum; D, dentin; Pc, pulp 
 chamber- De, dento-enamel junction; Ed, enamel defect; G, junction of enamel and 
 cementum at the gingival line; Gt, granular layer of Tomes. (Reduced from photo-micro- 
 graph made in three sections.) 
 
ENAMEL 63 
 
 conditions of the teeth, particularly those which involve the supporting 
 tissues. 
 
 Dental Tissues. — ^The human teeth are made up of four tissues 
 (Fig. 29). 
 
 1. The enamel covers the exposed portion of the tooth, or crown, 
 and gives the detail of crown form. Its function is to protect the tooth 
 against the wear of friction. 
 
 2. The dentin forms the mass of the tooth and determines its class 
 form, the number of cusps and the number of roots being indicated 
 by the dentin form. 
 
 3. Cementum covers the dentin beyond the border of the enamel, 
 overlapping it slightly at the gingival line and forming the surface 
 of the root. Its function is to furnish the attachment of the fibers 
 of the peridental membrane, which fasten the tooth to the bone. 
 
 4. The pulp or soft tissue filling the central cavity in the dentin is 
 the remains of the formative organ which has given rise to the dentin. 
 Its functions are the formation of dentin and a sensory function. 
 
 In describing the structure of the teeth and the arrangement of the 
 structural elements of the tissues, directions are described with refer- 
 ence to three planes: 
 
 The mesio-disto-axial plane, a plane passing through the center of 
 the crown from mesial to distal and parallel with the long axis of the 
 tooth. 
 
 The bucco-linguo-axial plane, a plane passing through the center of 
 the crown from buccal to lingual and parallel with the long axis of the 
 tooth. 
 
 The horizontal plane, at right angles to the axial planes. 
 
 The Supporting Tissues. — The human teeth are supported on the 
 maxillary bones, their alveolar processes growing up around the roots 
 of the teeth, so that the roots fit into the holes in the bone. The 
 calcified structures of the tooth and bone are not, however, united, 
 but the roots are surrounded by a fibrous membrane, the peridental 
 membrane, or pericementum, which fastens the tooth to the bone. 
 
 ENAMEL. 
 
 The enamel differs from all other calcified tissues in the nature of the 
 structural elements of which this tissue is made up, in the degree of 
 calcification, and in origin, being the only calcified tissue derived from 
 the epiblast. 
 
 The enamel is formed from an epithelial organ derived from the 
 epithelium of the mouth cavity and indirectly from the epiblastic 
 germ layer, while all other calcified tissues are products of the meso- 
 
64 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 blast. In the case of bone and dentin, the formative tissue is persistent. 
 It is possible in the bone at least, therefore, to have degenerative and 
 regenerative changes, or the removal of part of the calcium salts and 
 their replacement through the agency of the formative tissue; while 
 in the enamel no such regenerative change is possible, as the formative 
 tissue disappeared when the tissue was completed and before the 
 eruption of the tooth. 
 
 The enamel is the hardest of human tissues. Chemically it is com- 
 posed of the phosphates and carbonates of calcium and magnesium 
 and a very small amount of the fluorids, water, also a very small 
 amount of organic matter, if any."^ The enamel in the natural con- 
 dition, bathed in the fluids of the mouth, contains a considerable 
 amount of water. If dried at a little above the boiling-point of water, 
 it gives up part of it and shrinks considerably, so as to crack in fine 
 checks. If heated almost to redness, it suddenly gives off from 3 to 5 
 per cent, (of the dry weight) of water with almost explosive violence. 
 These facts were demonstrated some years ago by Charles Tomes,^ 
 and account for most of what was formerly recorded as organic matter 
 in old analyses. 
 
 If we observe under the microscope the action of acids upon thin 
 sections of enamel, when the inorganic salts are entirely removed, the 
 structure of the tissue vanishes, there being no trace of organic matrix 
 left as in the case of bone or dentin. In the growth of bone and dentin 
 the formative tissue produces first an organic matrix in the form of the 
 tissue, and into this inorganic salts are deposited, combining with the 
 organic substances of the matrix. This union is comparatively weak, 
 however, for by the action of acids the combination is broken up and 
 the inorganic salts are dissolved; or by heat the organic matter is 
 removed, and in either case the form of the tissue will be maintained. 
 
 In the case of the enamel, the formative organ produces organic 
 substances containing inorganic salts, and the substances are arranged 
 in the form of the tissue after the manner of a matrix; but finally, 
 under the action of the formative organ all of the organic matter is 
 removed and substituted by inorganic salts, whatever organic matter 
 is found in the fully formed tissue being the result of imperfect exe- 
 cution of the plan. 
 
 1 von Bibra gives the following analysis of enamel: 
 
 Calcium phosphate and fluorid 89.82 
 
 Calcium carbonate 4.37 
 
 Magnesium phosphate 1 . 34 
 
 Other salts 0.38 
 
 Cartilage 3.3i& 
 
 Fat 0.20 
 
 Total organic 3.59 
 
 Total inorganic 96.41 
 
 2 Journal of Physiology, 1896. . . 
 
ENAMEL 
 
 65 
 
 The enamel is composed of two structural elements, the enamel 
 rods, or prisms, sometimes called enamel fibers, and the inter prismatic 
 or cementing substance, both of which are calcified. It is to the arrange- 
 ment of these structural elements that the characteristics of the tissue 
 with which we are most concerned in operative procedures are due. 
 
 While both the prisms and interprismatic substances of the enamel 
 are calcified, or, better, composed of inorganic salts, the two substances 
 — that is, the substance of the rods and the substance between the 
 rods — show markedly different properties both chemical and physical. 
 If treated with acid, the interprismatic substance is acted upon more 
 rapidly than the rods, so that the latter become more conspicuous. 
 
 Isolated enamel rods. (About 1000 X.) 
 
 By this means sections of the enamel may be etched to render it easier 
 to study the direction and arrangement of the rods. If the action of 
 the acid is carried far enough, the rods will fall apart before they are 
 themselves entirely dissolved. Fig. 30 is from the debris in a carious 
 cavity, and shows rods isolated by the action of the acids of caries. 
 
 The interprismatic substance is not as strong as the rods, so that in 
 splitting or breaking the enamel the tissue separates on the lines of the 
 cementing substance, occasionally breaking across a few rods but 
 following their general direction, the lines running between rods, not 
 at their centers. 
 
 In cleaving the enamel the chisel does not enter the tissue separating 
 rod from rod, but the edge engages with the surface, and the force 
 5 
 
66 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 applied at an acute angle with the direction of the rods fractures the 
 tissue in the lines of least resistance. If the edge be keenly sharp, it 
 will enter the tissue slightly, and then the bevel acts as a wedge in 
 addition to the force applied to the shaft of the instrument; but if 
 the edge be dull, it will rest across the ends of many rods, will not 
 engage with the surface, and the force applied will break and crumble 
 the tissue but will not cleave it. 
 
 The enamel rods, or prisms, are long, slender prismatic rods or 
 fibers, five- or six-sided, pointed at both ends and alternately expanded 
 and constricted throughout their length. They are from 3.4 to 4.5 
 microns^ in diameter,, some of them apparently reaching the entire 
 distance from the siu-face of the dentin to the surface of the enamel; 
 but as the diameter of the rods is the same at their outer and inner 
 ends, and as the crown surface is much greater than the surface of 
 dentin covered by enamel, there are many rods which do not extend 
 through the entire thickness. These short rods end in tapering points 
 between the converging rods which extend the entire distance. To 
 express this in terms of development: as the formation of enamel 
 begins at the surface of the dentin, the increasing area of cro^^Ti surface 
 requires more ameloblasts, and as new ameloblasts take their place in 
 the layer, the formation of new enamel rods begins between the rods 
 which were previously forming. These short rods are most numerous 
 over the marginal ridges and at the points of the cusps, and will be 
 considered more fully in connection with those positions. 
 
 In ground sections cut at right angles to the direction of the rods,^ 
 the tissue has the appearance of a mosaic floor, the outline of the 
 rods being more distinct if they have been marked out by treating the 
 section slightly with acid (Fig. 31). In longitudinal sections (Fig. 32) 
 the sides of the rods are not smooth and even like the sides of a lead 
 pencil, but are alternately expanded and constricted. They are well 
 illustrated by taking balls of soft clay and sticking them together 
 one above another to form a rod, then putting a number of rods to- 
 gether so that by mutual pressure they take hexagonal forms. This 
 illustrates also the manner of gro\\i;h of the tissue in formation. The 
 expansions and constrictions can be seen in rods that have been scraped 
 from a cleaved surface of enamel, but better by isolating rods by the 
 slight action of dilute acid (Fig. 33). 
 
 In the construction of the tissue the rods are so arranged that the 
 expansions of one rod come opposite to the expansions in the adjoining 
 
 1 A micron is the unit of microscopic measurement, and is equal to one-thousandth 
 of a millimeter. 
 
 2 In describing the direction of enamel rods they are always considered as extending 
 from the dentin to the surface, and the angle is formed at the surface of the dentin 
 with the locating plane, either horizontal or axial. 
 
ENAMEL 
 
 67 
 
 rods, and do not interlock with their constructions. This arrangement 
 leaves alternately a greater and a less amount of cementing substance 
 between them. 
 
 Fig. 31. — Transverse section of enamel rods. (About 8U X.) 
 
 Fig. 32. — Enamel rods in thin etched section. (About 800 X.) 
 
 When observed under the microscope, the enamel rods show a 
 characteristic appearance of light and dark lines running across them. 
 These markings are similar to the striations of voluntary muscle fibers, 
 
68 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 and are described as the striation of the enamel. It is seen not only in 
 isolated rods, but also in sections ground in their direction (Fig. 34). 
 This appearance of striation in the enamel is caused by the alternate 
 
 Fig. 33. — Enamel rods isolated by scraping. (About 800 X.) 
 
 Fig. 34. — Enamel showing striation. (About 1000 X.) 
 
 expansions and constrictions of the rods refracting the light like a lens. 
 In sections the expansions in adjoining rods are opposite to each 
 other, the difference in the refracting power of the prismatic and inter- 
 prismatic substances producing the same effect. 
 
ENAMEL 69 
 
 The appearance of striation is the record in the fully formed tissue 
 of the manner of growth, each dark stripe, or expansion, in a rod 
 representing a globule of partially calcified material. The ameloblasts 
 build up the rods by the addition of globule after globule, surrounding 
 them with a cementing substance and completing the calcification of 
 both. In this sense the striation of the enamel may be said to record 
 the growth of the individual rods. 
 
 While the enamel is a very hard substance when its structure is 
 complete and perfect, its most striking physical characteristic is a 
 tendency to split or crack in the direction of its structura,l elements 
 when a break has been made in the tissue. While it is difficult to cut 
 across the rods or make an opening on a perfect surface, if a break has 
 
 Fig. 35. — Enamel showing direction of cleavage. (About 70 X.) 
 
 been established it is comparatively easy to split off the tissue from the 
 sides of the opening when the rods lie parallel with each other. Fig. 35 
 shows a field of enamel illustrating the way in which the tissue splits 
 or cleaves in the direction of the rods. 
 
 Upon the axial siu-faces the enamel rods are usually straight and 
 parallel with each other, except where there has been some flaw or 
 disturbance in development; but upon the occlusal surface, although 
 sometimes straight, they are ver}- often much twisted and wound round 
 each other, especially at their inner ends. This difference in the arrange- 
 ment of the rods causes the greatest difference in the feeling of the tissue 
 under cutting instruments. Such a specimen of enamel as sho\\Ti in 
 Fig. 36 can be cut away easily, the tissue breaking through to the 
 dentin and splitting oft' in chunks; while a specimen like Fig. 37 will 
 
70 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 Fig. 36. — Straight enamel rods. (About 80 X.) 
 
 
 _^_^...^ 
 
 Fig. 37. — Gnarled enamel. (About 80 X.) 
 
ENAMEL 
 
 71 
 
 not cleave if supported upon sound dentin. If the outer ends of the 
 rods are straight, they will split part way to the dentin (Fig. 38) ; but 
 where they begin to twist round each other they will break across the 
 rods. If the dentin is removed from under such enamel, it will break 
 in an irregular way through the gnarled portion. 
 
 Fig. 38. — Gnarled enamel. (About 50 X .) 
 
 From a study of the arrangement of the enamel rods in the formation 
 of the crown it is apparent that the plan is such as to give the greatest 
 strength to the perfect structure, and may be likened to an arch. At 
 the gingival border the rods are short and are inclined apically 6 to 10 
 centigrades^ (20° to 35°) from the horizontal plane. These short rods 
 
 1 In the centigrade division the circle is 
 divided into one hundred parts, each called 
 a centigrade. One centigrade is equal to 
 3.6 degrees of the astronomical circle, 25 
 centigrades to 90 degrees, 12 centigrades 
 to 45 degrees. The cut gives a compari- 
 son of the two systems of measuring 
 angles. 
 
 2 70 
 
 180 
 Centigrade division. 
 
72 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 are overlapped for a short distance by the cementum. This iiidination 
 grows less and less, and at some place in the gingival half of the middle 
 third of the surface they are in the horizontal plane. At this point 
 they are also usually perpendicular to the surface of the dentin. Pass- 
 ing from this point they become inclined more and more occlusally 
 from the horizontal plane, at the junction of the occlusal and middle 
 thirds about 8 to 12 centigrades (28° to 40°) in bicuspids and molars, 
 and 8 to 18 centigrades (28° to 65°) in incisors and canines. In the 
 occlusal third the inclination increases rapidly, and often the outer 
 
 Fig. 39. — Diagram of enamel rod directions, from a photograph of a bucco-lingual sec- 
 tion of an upper bicuspid. 
 
 ends of the rods are inclined more than the inner ends. Over the point 
 of the cusps and the crest of the marginal ridges the rods reach the 
 axial plane, though they are often very much twisted about each other 
 in the inner half of their length. This position does not always corre- 
 spond with the highest point of the cusp, but is inclined slightly axially 
 from that position, and corresponds with the highest point of the dentin 
 cusp. 
 
 Passing down the central slope of the cusp, or ridge, the rods become 
 again inclined away from the axial plane toward the groove, or pit. 
 
ENAMEL 
 
 73 
 
 leaning toward each other where the two plates meet. The degree of 
 inclmation of the rods on the central slope of the cusps depends upon 
 the height of the cusps; the higher the cusp the greater the inclination 
 from the axial plane. Fig. 39, a diagram from a photograph of a 
 bucco-lingual section of an upper bicuspid, shows the plan of arrange- 
 ment and illustrates the arch principle in the construction. 
 
 Fig. 40. — Stratification of enamel; the cusp of a bicuspid: De, dento-enamel junction; 
 Ed, enamel defect showing in the heavy stratification band ; Ig, interglobular spaces in 
 the dentin. (About 40 X.) 
 
 In the study of longitudinal sections of the teeth, one of the most 
 conspicuous structural features is the stratification bands or brown 
 bands of Retzius. These bands are not parallel with either the outer 
 surface of the enamel or the dento-enamel junction. They begin at 
 the tip of the dentin cusps and sweep around in larger and larger zones. 
 
74 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 Fig. 41. — -Incisor tip showing stratification or incremental lines. Rods at A were fully 
 formed at the time the rods at B were beginning to form. (About 50 X.) 
 
 Fig. 42. — -Enamel showing both striatiou and stratification. (About 80 X.) 
 
REQUIREMENTS FOR STRENGTH IN ENAMEL WALLS 75 
 
 These stratification bands are better seen in comparatively thick 
 sections, and are caused by the varying amount of pigment deposited 
 with the calcium salts in the development of the tissue. They record 
 the growth of enamel of the crown as a whole, as each line was at one 
 time the surface of the enamel cap. These stratifications, or better, 
 incremental lines, are shown in Fig. 40. 
 
 At the time the rod at A (Fig. 41) was completely formed the rod 
 at B was just beginning to form at its dentinal end. From this it would 
 seem that any structural defect due to imperfect development would 
 not follow the direction of the enamel rods from the surface to the 
 dentin, but would follow the stratification lines; and if these struc- 
 tural defects influenced the penetration of caries, we should expect to 
 have the direction of penetration modified. Fig. 42 shows a structural 
 defect in the enamel over a cusp following the stratification band, and 
 it will be noticed also that there is a structural defect in the dentin at a 
 corresponding position. 
 
 HISTOLOGICAL REQUIREMENTS FOR STRENGTH IN ENAMEL 
 
 WALLS. 
 
 1. The enamel must be supported upon sound dentin. 
 
 2. The rods which form the cavo-surface angle must run uninterrupt- 
 edly to the dentin and be supported by short rods, with their inner ends 
 resting on the dentin and their outer ends abutting upon the cavity 
 wall, where they will be covered in by the filling material. 
 
 3. That the cavo-surface angle be cut in such a way as not to expose 
 the ends of the rods to fracture in condensing and filling material 
 against them. 
 
 In thinking of the supporting tissues it has been too much the habit 
 to think of the bone and the fibrous tissues as separate entities or 
 anatomically distinct things. Instead of this point of view, the sup- 
 porting tissues should be thought of as a connected tissue organ of 
 support, part of which is calcified for the purpose of rigidity. The bone 
 of the alveolar process, the fibrous tissue of the peridental membrane, 
 periosteum and septal tissue should be thought of as only parts of a 
 whole which function as an organ of support to the denture, sustaining 
 the teeth in their function and keeping the epithelium in proper relation 
 to the teeth for the protection of the supporting tissues from injury 
 and infection. 
 
 The first step, then, in the preparation of an enamel wall is to deter- 
 mine the direction of the enamel rods by cleavage with a chisel or 
 hatchet. In Fig. 43, No. 1 shows an enamel wall after cleaving the enamel 
 with a hatchet. It will be noticed that the split has not followed the 
 
76 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
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REQUIREMENTS FOR STRENGTH IN ENAMEL WALLS 77 
 
 direction of the rods exactly, but has broken across them, slivering the 
 rods as wood slivers in splitting. This would cause in the cut surface 
 a whitish, opaque appearance. The plane of the enamel wall should 
 
 be extended so as to form a small angle with the plane of the dental 
 wall, by shaving the surface with a very sharp hand instrument. No. 
 2 shows the same wall after it has been extended somew^hat; but it 
 
78 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 will be seen that it has not been extended enough, for the rods forming 
 the surface at A do not reach the dentin, but run out at B on the 
 cavity wall, and that piece would chip out in packing against it or if 
 force came upon the surface afterward. The angle should be extended 
 so as to produce the plane shown in No. 3; then the cavo-surface angle 
 may or may not be beveled as the position demands. 
 
 Fig. 45. — Occlusal fissure in an upper bicuspid, showing direction of rods. (About SOX.) 
 
 With reference to the direction of the enamel rods in relation to the 
 cavity, enamel walls may be divided into two classes: (1) those in 
 which the rods are inclined toward the cavity, characteristic of grooves, 
 fissures, and pits; and (2) those in which the rods are inclined away 
 from the cavity, characteristic of cavities beginning on smooth axial 
 surfaces. In the first it is easy to obtain the structural requirements for 
 
REQUIREMENTS FOR STRENGTH IN ENAMEL WALLS 79 
 
 a strong wall. In the second it is comparatively difficult. It is impor- 
 tant to remember that strength is measured by the degree to which the 
 structural requirements are attained. 
 
 Grooves, fissures, and pits are always positions of weakness, and 
 when a cavity approaches a groove or pit. a good margin, histologically, 
 cannot be prepared without cutting beyond it. Fig. 45 shows an 
 
 Fig. 46. — Bucco-lingiial section of upper bicuspid; enamel is broken from grinding: 
 A to B, area of weakness for enamel margins. (About 20 X.) 
 
 occlusal fissure in a bicuspid, which illustrates the conditions of struc- 
 ture characteristic of these positions. The rods are inclined toward the 
 fissure, and between the bottom of the fissure and the dentin are very 
 irregular. If a cavity wall were made to approach this fissure from the 
 lingual side, so as to come to the dotted line, the wall would have to be 
 inclined 6 to 8 centigrades (20° to 28°) from the axial plane toward the 
 fissure, and then the cavo-surface angle beveled, when the conditions 
 
80 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 would be similar to those in the wall of an axial surface cavity, and 
 not as strong as the location requires. Not only is this true, but it also 
 leaves a vulnerable point next to the margin of the filling— a point of 
 
 Fig. 47. — Enamel over tip of dentin cusp: D, dentin cusp. (About 80 X.) 
 
 liability. Cutting just beyond the fissure, the wall may be left in the 
 axial plane and have an ideally strong margin, and the point of liability 
 is removed. To state the conditions in general terms, a strong margin 
 
DENTIN 81 
 
 is more easily obtained where enamel rods are inclined toward the 
 cavity than where they are inclined away from the cavity. 
 
 The points of cusps and the crests of marginal ridges are positions 
 of strength in the perfect tissue; but when a cavity margin approaches 
 them they become points of weakness, because it is impossible to sup- 
 port properly the rods which form the margin. Over the marginal 
 ridges are many short rods which do not reach the dentin, and these are 
 usually very much twisted about each other, so as to form the strongest 
 possible keystone in the perfect structure. In preparing a margin in 
 such a position it is impossible to have the rods which form the margin 
 reach the dentin with their inner ends, and these short rods are sure 
 to break in completing the operation or to break out later. The 
 arrangement of enamel rods in such positions is to be borne in mind, 
 especially when extending approximate cavities in incisors toward 
 the lingual side and in large pit cavities in incisors. A similar condition 
 is found over the points of the cusps. Fig. 46 shows a bucco-lingual 
 section of an upper bicuspid. It will be noticed that the rods forming 
 the point of the cusp are not in the axial plane, and do not reach the 
 tip of the dentin cusp, but reach the dentin a little way down on the 
 outer slope. The enamel covering the tip of the dentin contains many 
 short rods, and they are very much twisted about each other, so that 
 the area from A and B to the point of the cusp is an area of weakness 
 for the cavity margins. If the margin reaches this area, the cusp must 
 be cut away and the enamel wall carried out in the horizontal plane. 
 Fig. 47 shows this area more highly magnified, and illustrates the 
 structure. It will be noticed that, in grinding, some of the short 
 twisted rods have broken out of the section. 
 
 DENTIN. 
 
 Dentin belongs to the connective-tissue group, and is made up of a 
 solid organic matrix impregnated with about 72 per cent, of inorganic 
 salts^ and pierced by minute canals or tubuli, which radiate from a 
 central cavity which contains the remains of the formative organ, or 
 pulp. The minute canals, or dentinal tubuli, are occupied in life by 
 protoplasmic processes from the odontoblastic cells which form the 
 
 1 von Bibra gives the following analysis of dentin: 
 
 Organic matter 27.61 
 
 Fat '....-.. 0.40 
 
 Calcium phosphate and fluorid 66.72 
 
 Calcium carbonate 3.36 
 
 Magnesium phosphate 1 . 08 
 
 Other salts 0.83 
 
 6 
 
82 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 outer layer of the pulp. Dentin contains two kinds of organic matter, 
 the contents of the tubuli and the organic basis of the matrix. 
 
 From a study of microscopic sections it appears that the total volume 
 of the dentinal tubuli amounts to approximately one-tenth of the entire 
 volume of the dentin. The contents of these spaces and its fate are 
 important factors in the question of pulpless teeth. Unfortunately 
 very little is positively known about the contents of the dentinal tubuli. 
 And there is a very great diversity of opinion among the authorities 
 on the subject. During the formation of dentin, it is apparent that 
 protoplasmic projections of the odontoblasts are left in the dentinal 
 tubuli (though this is disputed by some authors, see Hopewell-Smith) ; 
 but whether this condition is permanent or not is by no means certain. 
 Some authors (Howard Mummery) claim to have demonstrated nerve 
 fibers in the dentinal tubuli; at present the author feels that much 
 work must be done on this subject before the facts are clearly estab- 
 lished. In recent study the author has been convinced that in the 
 formation of dentin many cells are enclosed in the matrix but what 
 their fate is and what is their relation to the matrix is not known. 
 
 The dentin matrix, after the removal of the calcium salts by acids, 
 yields gelatin on boiling and resembles the matrix of bone, reacting in 
 a similar, though not identical, way with staining agents. The por- 
 tion of the matrix immediately surrounding the tubuli shows different 
 chemical characteristics from the rest of the matrix, resembling elastin, 
 and resisting the action of strong acids and alkalies after the rest of the 
 tissue has been destroyed. This portion of the matrix surrounding 
 the tubuli and lying next to the fibrils is known as the sheaths of 
 Neumann. 
 
 The dentinal tubuli are from 1.1 to 2.5 microns in diameter, and 
 are separated from each other by a thickness of about 10 microns of 
 dentin matrix. This is fairly uniform throughout the dentin. The 
 character of the tubuli is different in the crown and root portions. 
 
 In the crown the tubuli branch little through most of their course; 
 but in the outer part, close to the enamel, they branch and anastomose 
 with each other quite freely. Fig. 48 shows a field of dentin just 
 beneath the enamel, as seen with a high power and shows the diameter 
 of the tubuli, their branching, and the amount of matrix between one 
 tubule and the next. The relation of one tubule to another is shown 
 also in sections cut at right angles to their direction (Fig. 49). In 
 the crown portion the tubuli pass from the pulp chamber to the 
 dento-enamel jmiction in sweeping curves, so as to enter the pulp 
 chamber at right angles to the surface, and end next to the enamel 
 at right angles to that surface. This produces S- or F-shaped ( C ) 
 curves, which are known as the primary curves of the tubuli. 
 
DENTIN 
 
 83 
 
 Fig. 48. — Dentin at dento-enamel junction, showing tubuli cut longitudinally: Dt, 
 dertinal tubuli; D, dentin matrix. (About 760 X.) 
 
 
 ■HSi 
 
 m 
 
 ■ 
 
 V~ 
 
 ^^ € 
 
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 Fig. 49. — Dentin, showing tubuli in cross-seetii)n: Dt, dentinal tiitnili; D, dentin 
 matrix; S, shadow of sheaths of Neumann. (About 1150 X.) 
 
84 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 Throughout theu" coiuse the tubuh are not straight, but show a great 
 many wavy curves, known as the secondary ciu'ves. These appear 
 as waves when seen in longitudinal sections, but are really the effect 
 of an open spiral direction, as is seen by changing the focus of the 
 microscope in studying sections cut at right angles to the direction of 
 the tubuli. The branches throughout their length are few and small 
 and are given oft' at an acute angle to the direction of the tubule; but 
 just before the enamel is reached the tubuli fork and branch producing 
 an appearance similar to the delta of a river. These branches are given 
 
 Fig. 50. — -Crown of a molar, mesio-distal section, sho\^'ing penetration of caries : A , caries 
 penetrating dentin; B, line of abrasion; P, pulp chamber. (About 20 X.) 
 
 off from the tubuli for some little distance back from the enamel, and 
 they anastomose with other tubuli very freely. The branching of the 
 tubuli in their outer portion causes the spreading of caries. Just 
 beneath the enamel the microorganisms growing through the branches 
 from tube to tube, spread sideways beneath the enamel plates, and 
 penetrate the dentin in the direction of the tubuli. Fig. 50 shows the 
 penetration of caries in the dentin. It will be noticed that in decay 
 starting at the contact point, there has been more spreading under the 
 enamel than in that starting at the gingival line, but in both positions 
 the penetration has followed the direction of the tubuli. 
 
DENTIN 
 
 85 
 
 In the root portion the tubuli pass out from the pulp canals at right 
 angles to the long axis of the tooth and pass directly out to the cemen- 
 tum, showing only the secondary curves. Throughout their course 
 they give off a great many fine branches passing through the matrix 
 in all directions from tubule to tubule. These branches are so muner- 
 ous that in sections which have been mounted in such a way as to leave 
 air in them, or if the tubuli have been filled with coloring matter, they 
 give the impression of looking through a hazel bush; or they may be 
 
 Fig. 51. — Dentin from the root, showing tubuli cut longitudinally. (About 700 X.) 
 
 likened to the fine rootlets of a plant. These fine branches are shown 
 in Fig. 51, and the character of the dentin in the root portion is to be 
 compared with that in the crown portion as showm in Fig. 48. The 
 outermost layer of the dentin next to the cementum contains many 
 small irregular spaces, which connect with the dentinal tubuli and 
 give to the tissue when seen with low powers a granular appearance. 
 This layer was first described by John Tomes as the granular layer, and 
 has since been usually called the granular layer of Tomes. The spaces 
 of the granular layer are probably filled by the enlarged ends of the 
 
86 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 Fig. 52. — -Dento-enamel junction. (About 70 X.) 
 
 
 > 
 
 i'h' }"'■/ 
 
 ¥ 
 
 ¥i3,. 53. — Interglobular spaces in dentin: Ig, first line of interglobular spaces ; Ig', second 
 line of interglobular spaces. (About 30 X.) 
 
DENTIN 
 
 87 
 
 dentinal fibrils. The same appearance is sometimes seen beneath the 
 enamel, but is never as well marked as next to the cementum. 
 
 In recent study of material prepared by Dr. Newton G. Thomas 
 and Dr. William S. Skillen the author has been convinced that the 
 spaces in the granular layer of Tomes are formed and occupied by 
 cells enclosed in the formation of the matrix, but whether they are 
 persistent or not seems doubtful. 
 
 Fig. 54. — -Granular layer of Tomes: L, lacunse of cementum; Gt, granular layer of Tomes; 
 Ig, interglobular spaces. (About 200 X.) 
 
 The dentin at the dento-enamel junction seldom presents a smooth 
 surface, but the inner surface of the enamel plate shows rounded pro- 
 jections, between w^hich the dentin extends. In sections this gives 
 to the dento-enamel junction a scalloped appearance as shown in 
 Fig. 52; and often the deceptive appearance of the dentinal tubuli 
 penetrating for a short distance between the enamel rods. 
 
 In many specimens made by grinding dried teeth, large irregular 
 spaces are very conspicuous in the dentin. They usually occur in 
 lines or zones at about uniform depth from the surface. These have 
 
88 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 been called the interglobular spaces. They are really not spaces at all, 
 but are areas of imperfect development in which the dentin matrix 
 has not been classified. The dentinal tubuli pass through them without 
 interruption. In a dried specimen the organic matrix shrinks, and the 
 resulting space becomes filled with debris of grinding, so as to give the 
 appearance of black spaces. Fig. 53 shows two quite distinct layers of 
 interglobular spaces, the second much more marked than the first; 
 and in the enamel at a position corresponding to the first is seen an 
 
 Fig. 55. — Granular layer of Tomes: L, lacunge of cementum; GT, granular layer of 
 Tomes; Iff, interglobular spaces. (About 200 X.) 
 
 imperfection of structure marked by the very dark stratification band. 
 This is shown best in the region of the cusp (Fig. 40) from the same 
 section. Interglobular spaces in the root portion of the dentin are 
 shown in Fig. 54, close to the granular layer of Tomes. 
 
 The formation of dentin is not complete at the period of eruption of a 
 tooth, but continues for an indefinite period, thickening the layer of 
 dentin at the expense of the pulp. When the typical amount of dentin 
 has been formed the growth ceases, and does not begin again unless 
 
PULP 89 
 
 excited by some irritation to the pulp or the pulp of some other tooth 
 of the same side, which leads to the formation of a secondary dentin. 
 Secondary dentin is never as perfect in structure as primary dentin; 
 the tubuli are smaller, fewer, and much more irregular. Often in 
 ground sections several periods of formation can be determined by 
 differences in structure, each deposit becoming successively more and 
 more imperfect in structure. This is shown in Fig. 55. 
 
 PULP. 
 
 The dental pulp is the soft tissue occupying the central cavity of the 
 dentin. It is made up of embryonal connective tissue and contains a 
 large number of bloodvessels and nerves. Like all connective tissues, 
 the intercellular substance is large in amount and the cells are widely 
 scattered in this soft, jelly-like tissue, which contains but few fibers. 
 We recognize four kinds of cells in the pulp : the odontoblasts, forming 
 the outer surface of the pulp next to the dentin; and round, spindle- 
 shaped, and stellate connective-tissue cells. 
 
 Arrangement of Cells. — ^The odontoblasts are tall columnar cells, 
 sometimes club-shaped, and in older tissues, which have ceased to be 
 functional, sometimes become almost spherical. They form a con- 
 tinuous layer over the entire surface of the pulp, being everywhere in 
 contact with the dentin. The layer has been called the membrana 
 eboris, or the "membrane of the ivory." 
 
 The nuclei of the odontoblasts are large and oval, contain a large 
 amount of chromatin, and are very different from the nuclei of ordinary 
 connective-tissue cells. 
 
 Three kinds of processes have been described in connection with the 
 odontoblasts : 
 
 1. The dentinal fibril processes or fibers of Tomes. These are long, 
 slender protoplasmic processes projecting from the dentin end of the 
 cell into a dentinal tubule, and running through the tubule to the 
 outer surface of the dentin. Usually there is but one fibril extending 
 from each odontoblast, but sometimes two can be seen, extending into 
 two tubuli. These fibrils can be demonstrated in decalcified sections 
 or by removing the pulp from a recently extracted tooth by cracking 
 the tooth and carefully lifting the pulp out of the pulp chamber, and 
 then either teasing or sectioning. Fig. 56 shows the fibrils projecting 
 from the surface; but in this section the cut was not in the direction of 
 the long axis of the odontoblasts, but obliquely through them. Fig. 57 
 (from a photograph by Rose) shows the form of the odontoblasts in a 
 young tooth in which formation of dentin is actively progressing, with 
 the fibrils in the dentinal tubuli. 
 
90 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 2. Lateral processes projecting from the sides of the cells and uniting 
 one with another in the formation of the layer. 
 
 Fig. 56. — ^Odontoblasts. The section cuts obliquely through the odontoblasts: F, 
 fibrils; A?', nuclei of odontoblasts; iV', nuclei of connective-tissue cells; W, layer of Weil, 
 not well shown. (About 80 X.) 
 
 Fig. 57. — Odontoblasts and forming dentin: E, forming enamel; D, forming dentin- 
 O, odontoblasts; Dp, body of dental papilla. (From photo-micrograph by Rose.) 
 
PULP 91 
 
 3. Piilpal processes, projecting from the pulpal ends of the odonto- 
 blasts into the layer of Weil. 
 
 The odontoblasts, as the name indicates, are the dentin-forming 
 cells. They superintend the formation and calcification of the dentin 
 matrix, the fibril being left behind surrounded by the formed tissue. 
 Whether the fibrils have any share in the formation and calcification 
 of the dentin matrix has been a matter of controversy. 
 
 One author claims that the odontoblasts have no part in the for- 
 mation of dentin, but it seems incredible that this view could be held 
 by anyone who had made even a superficial examination of the tissues 
 during dentin formation. 
 
 The relation of the fibrils to the transmission of sensation is also a 
 matter of dispute; but at present the weight of evidence is that they 
 in some way transmit impressions to the sensory nerves of the pulp. 
 
 The relation of the odontoblasts and the fibril to the dentin matrix 
 is of great importance just now in the solution of the problem of the 
 pulpless tooth. It is important to remember that the dentin matrix 
 is a formed material of the same general class as other intercellular 
 substances and its relation to the odontoblasts and fibril is the same as 
 other intercellular substance and the cells which produce them. In 
 other words, there is a chemical relation between the cell and its inter- 
 cellular substance in which the cell and the normal circulation of 
 lymph are necessary to the maintenance of the intercellular substance 
 in its chemical and physical properties. When the cells in bone are 
 killed, the intercellular substance or bone matrix becomes a foreign 
 body and undergoes chemical and physical change. When the pulp is 
 removed from the dentin the dentin matrix becomes a dead substance, 
 a foreign body, it undergoes physical and chemical change as Black 
 demonstrated twenty-five years ago. Dentin from a pulpless tooth is 
 very much more easily broken than that from a vital, tooth, and would 
 be expelled from the body were it not for the fact that between it and 
 any other vital tissue is another tissue, the cementum, which encloses 
 the dentin and its vitality is not destroyed by the death of the dentin. 
 The only reason that a pulpless tooth is not exfoliated is because the 
 dead dentin is enclosed in living cementum.^ 
 
 The question as to what becomes of the dentinal tubuli and whether 
 they may produce decomposition products or split proteid elements 
 which reduce the vitality of neighboring tissues and render them liable 
 to the invasion of infection cannot be answered until a great deal of 
 hard work has been done in the laboratory. 
 
 1 The question as to whether the death of the dentin affects the vitality of the cemen- 
 tum in any degree is a matter of discussion at present. 
 
92 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 In the opinion of the author very Httle is really known about the 
 contents of the dentinal tubuli. 
 
 Just beneath the layer of odontoblasts is a zone which contains 
 very few connective-tissue cells. In thin sections, especially in the 
 body of the pulp, this appears as a clear layer about half as thick as the 
 layer of odontoblasts. It is known as the layer of Weil. Just beneath 
 the layer of Weil the connective-tissue cells are especially numerous 
 and form a more or less distinct layer of closely placed cells. In the 
 rest of the body of the pulp the cells are about uniformly distributed 
 throughout the intercellular substance. These connective-tissue 
 cells are of the characteristic forms, rather small, containing a small but 
 deep-staining nucleus, the protoplasm stretching out into slender 
 projections in two directions to form the spindle cells, or in more than 
 two directions to form the stellate cells. The stellate forms are more 
 common in the body of the pulp, the spindle form in the canal portions. 
 The round cells are comparatively few in number, and are probably 
 young cells which have not yet acquired the adult form. 
 
 Bloodvessels of the Pulp. — ^The blood-supply of the pulp is ex- 
 tremely rich, several arterial vessels entering in the region of the apex of 
 the root, often through several foramina. These large vessels extend 
 occlusally through the central portion of the tissue, giving off many 
 branches which break up into a very close and fine capillary plexus 
 (Fig. 58). From the capillaries the blood is collected into the veins, 
 which pass apically through the central portion of the tissue. A very 
 striking peculiarity of the bloodvessels of the pulp is the thinness of 
 their walls. Even the large arteries show scarcely any condensation of 
 fibrous tissue around them to form the usual adventitious layer, and 
 usually contain but a single involuntary muscle fiber representing the 
 media, while the walls of even the large veins are made up of only the 
 single layer of endothelial cells forming the intima and are in structure 
 like large capillaries (Fig. 59). This peculiarity of the bloodvessel 
 walls is of great importance as it renders the tissue especially liable to 
 such pathologic conditions as hyperemia and inflammation. 
 
 The lymphatic circulation of the dental pulp and the presence or 
 absence of lymphatic vessels in the tissue have been matters of dispute 
 for many years. 
 
 In 1909 Sweitzer demonstrated lymph vessels in the dental pulp by 
 injection.^ Since that time Sweitzer's work has been repeated in this 
 country and the direct injection of lymph vessels in the cervical glands 
 through the dental pulp has been accomplished. ^ 
 
 1 "Ueber die Lymphgefasse des Zahnfleisches u. der Zahne beim Menschen u. bei 
 Saugetieren," Arch. f. mikrosk. Anat. u. Entwickl., 1907, Ixix, p. 807; 1909, Ixxiv, p. 927. 
 
 2 Kaethe Dewey, Frederick B. Noyes: Dental Cosmos, 1917. 
 
PULP 
 
 93 
 
 ■.\ X', 
 
 
 
 
 y -I 
 
 Fig. 58. — Diagram of the bloodvessels of the pulp. (Stowell.) 
 
 Fig. 59. — Dog's head, showing lymphatic glands injected from dental pulp. 
 
94 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 The lymph is collected in very delicate vessels that have been fol- 
 lowed to theTegion of the odontoblastic layer. The vessels pass to the 
 apical region following the same course as the large bloodvessels. 
 Both independent vessels and perivascular lymph sheaths have been 
 demonstrated. The vessels leave the pulp through the apical foramina, 
 anastomose freely with those of the peridental membrane in the apical 
 portion, and pass through the bone to the inferior dental canal in the 
 lower jaw and the infra-orbital canal in the upper. They have been 
 demonstrated emerging from the mental and infra-orbital foramina 
 and followed to the submaxillary lymph glands. It is probable that 
 some of the incisors drain to the submental lymph nodes and that 
 probably the second and third molars communicate with lymph 
 vessels emerging from the posterior opening of the inferior dental and 
 infra-orbital canals and pass to the lymph nodes of the pharynx. Much 
 work is still to be done in this field. There is also some experimental 
 evidence that there is a flow or circulation of lymph in the tubuli of 
 the dentin, which is quite logical from a priori reasoning. 
 
 Nerve of the Pulp. — Several comparatively large bundles of medul- 
 lated nerve fibers, containing from six or eight to fifteen or twenty 
 fibers, enter the pulp in company with the bloodvessels and pass 
 occlusally through the central portion of the tissue. These bundles 
 branch and anastomose with each other very freely. Most of the fibers 
 lose their medullary sheath before reaching the layer of Weil, in which 
 position they form a plexus of non-medullated fibers; from these fibers 
 free endings are given ofl^, which penetrate between the odontoblasts. 
 In some cases these have been followed over on to the dentinal ends of 
 the odontoblasts, but in no instance have they been followed into the 
 dentinal tubuli. 
 
 In the opinion of the author the work of Carl Huber ^ though done 
 many years ago remains the most convincing of any on the enervation 
 of the dental pulp. Several authors have claimed to demonstrate 
 nerve fibers in the dentinal tubuli, but in the opinion of the author 
 the evidence based upon the gold chlorid method alone must be con- 
 sidered as unsatisfactory, and at least capable of other interpretation. 
 
 The Functions of the Pulp. — The pulp performs two functions, a 
 vital and a sensory. '^} 
 
 The vital function is the formation of dentin, and is performed 
 by the layer of odontoblasts. This is the principal function of 
 the pulp, and it is first manifested in the development of the tooth 
 before the dentinal papilla is converted into the dental pulp by being 
 enclosed in the formed dentin. After the tooth is fully formed the 
 
 1 Dental Cosmos, 1898. 
 
PIG. 1 
 
 FIG. 2 
 
 FIG. 8 
 
 
 Fig. 1. — Tooth split open, showing pulp and pulp ehaniber and. 
 lymphatic vessels as seen with magnification of about lO diameters. 
 Fig. 2. — Injected lymphatic vessels in the dental pulp. 
 Fig. S. — Injected perivascular lymph sheath. 
 
CEMENTUM 95 
 
 vital function is not manifested unless the pulp is stimulated by some 
 excitation affecting trophic centers and which causes the formation of 
 secondary dentin. There are some exceptions where the formation 
 is entirely local. 
 
 The Sensory Function. — In regard to sensation the pulp resembles 
 an internal organ. It has no sense of touch or localization, and responds 
 to stimuli only by sensations of pain. The pain is usually localized 
 correctly with reference to the median line, but, aside from that, is 
 localized only as it is referred to some known lesion. If several pulps 
 on the same side of the mouth and in teeth of both the upper and lower 
 arches were exposed so that they could be irritated without impressions, 
 reaching the peridental membrane, and the patient were blindfolded, 
 it would be impossible for him to tell which of the pulps was touched. 
 The pain originating from a tooth pulp may be referred to the wrong 
 tooth or to almost any point on the same side supplied by the fifth 
 cranial nerve. 
 
 The pulp is especially sensitive to changes of temperature, but is 
 incapable of differentiating between heat and cold; this fact is often 
 made use of in differential diagnoses (see Chapter XVI). The pulp 
 is also very sensitive to traumatic and chemical irritations, even when 
 these are conveyed to it through the agency of the dentinal fibrils. 
 Dr. Huber^ has suggested that this transmission may be accomplished 
 by the traumatic or chemical action upon the fibrils setting up meta- 
 bolic changes in the odontoblastic cells which act as stimuli to the 
 sensory nerves ending between the cells of that layer. 
 
 CEMENTUM. 
 
 The cementum covers the surface of the dentin apically from the 
 border of the enamel lapping slightly over the enamel at the gingival 
 margin (Plate I, Fig. 1). 
 
 This is undoubtedly the normal and ideal relation, though in many 
 extracted teeth it will be found otherwise.^ It forms a layer, thickest 
 in the apical region and between the roots of bicuspids and molars, 
 and becoming thinner as the gingival line is approached. The cemen- 
 tum resembles subperiosteal bone in structure, but differs from it in 
 the character and arrangement of the lacunae and in the absence of 
 Haversian systems; the layers or lamellae of the cementum also are 
 less uniform in character than those of bone. 
 
 The function of the cementum is to furnish attachment for the 
 fibers of the peridental membrane which holds the tooth in its position. 
 
 1 Dental Cosmos, 1898. 
 
 2 Hopewell-Smith: Normal Histology, p. 18. 
 
96 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 The surrounding tissues are never in physiologic connection with the 
 outer surface of the dentin, except to form cementum over it or to 
 remove its substance by absorption; and when absorption of the dentin 
 has occurred on the surface of a root, it is never repaired except by the 
 formation of cementum to fill up the cavity and reattach the membrane. 
 
 The cementum is intermittently formed during the functioning of 
 the tooth, being added layer after layer over the entire surface of 
 •the root, the difference in thickness of the tissue in the gingival and 
 apical portions being chiefly, though not entirely, due to the difference 
 in thickness of each layer in the two positions (Plate I, Fig. 2). The 
 cementum on the roots of newly erupted teeth is thin, and on the roots 
 of teeth of old persons is thick. This continued formation of cementum 
 is due to the necessity for change and reattachment of the fibers of the 
 membrane. 
 
 In the gingival portions, where the cementum is thin, the tissue is 
 clear and apparently structureless, and usually contains no lacunae; 
 while in the apical half and between the roots the lacunae are numerous. 
 In general, wherever the lamellse are thin, the lacunse are absent; but 
 where the lamellae are thick, they are found. The canaliculi which 
 radiate from the lacunse are not as regular as in the case of the lacuna? 
 of the bone. Sometimes they are numerous, sometimes few; they may 
 extend from a lacuna in all directions, or they may be confined to one 
 side, usually the side toward the surface of the cementum (Plate I, 
 Fig. 3). 
 
 The cementum is penetrated through all its layers by fibers of the 
 peridental membrane which have been imbedded in the matrix of the 
 tissue and calcified along with it. The first layer — that is, the one 
 next to the dentin — is usually structureless and- shows no fibers in it, 
 at least in its inner half. In ground sections the imbedded fibers often 
 appear in a number of layers, while they are not apparent in the rest 
 of the thickness. This is because just before and just after the for- 
 mation of the layers in which they appear the fibers were cut off and 
 reattached, changing their direction, so that in the other layers the 
 fibers are cut transversely or obliquely. This is illustrated in Fig. 60. 
 These imbedded fibers are very numerous in some places. If properly 
 stained, the tissue seems almost a solid mass of fibers. In ground sec- 
 tions they have sometimes been mistaken for minute canals from the 
 fact that they are not always as fully calcified as the cementum matrix, 
 and shrinkage causes the appearance of little open canals. 
 
 There has been much discussion recently of the relation of the dentin 
 and cementum, and the nourishment of the cementum. Much of the 
 discussion shows lack of the fundamental considerations of cytology, 
 tissue structure, nutrition, metabolism, and other biological ideas. 
 
CEMENTUM 
 
 97 
 
 The author is of the opinion that most of the root communications 
 between the lacunse and canaHcuh of the cementum and the tubuH of 
 the dentin are not typical of the tissue if they ever occur. From a 
 study of the formation of cementum and dentin it is evident that the 
 formation begins at the dento-cemental junction just as that of enamel 
 and dentin begins at the dento-enamel junction. The formation of 
 dentin proceeds from this line inward and that of the cementum out- 
 
 FiG. 60. — -Two fields of cementum showing penetrating fibers: Gt, granular layer of 
 Tomes; C, cementum not showing fibers; F, penetrating fibers. (About 54 X.) 
 
 ward. The formative process as well as the tissue produced is sup- 
 ported, for the dentin by the pulp, for the cementum by the peridental 
 membrane. While it is quite evident that there may be occasional 
 communication between the channels in the dentin matrix and those in 
 the cemental matrix, it seems well established that the nourishment 
 of one tissue is not dependent upon, or even related to, the other. 
 The relation of dentin and cementum in the region of the apex 
 7 
 
98 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 of the root becomes very complicated because of the way in which the 
 formation of the root apex is accomphshed, and the structure in this 
 region becomes important in the pathology of the region.^ 
 
 Hypertrophies of the cementum (formerly often called exostoses, 
 or excementoses) are very common. The increased thickness may be of 
 one lamella or of several lamellse in the region of the hypertrophy, or 
 all of the layers from first to last may take part in it. Small local 
 thickenings of a single lamella are seen in connection with the peri- 
 dental membranes wherever an especially strong bundle of fibers is to 
 be attached to the root to support the tooth against some special 
 strain. 
 
 PERIDENTAL MEMBRANE. 
 
 The peridental membrane may be defined as the tissue which fills 
 the space between the root of the tooth and the bony wall of its alveolus, 
 surrounds the root occlusally from the border of the alveolus, and sup- 
 ports the gingiva. 
 
 It is important to emphasize the three parts of the membrane and 
 to call attention to the fact that the membrane clothes the root 
 occlusally from the border of the alveolar process as far as the tissues 
 are attached to the cementum and supports the epithelium of the 
 gingiva. 
 
 There has been much discussion as to the origin of the myeloplax 
 or giant absorbing cells. Some have claimed that they are degenerate, 
 fused, osteoclasts^ It seems more probable to the author that they 
 originate from the endotheloid cells of the connective tissue which 
 at first act singly, but fuse as the area of absorption increases. It has 
 been referred to under many names, as pericementum, dental perios- 
 teum, alveolo-dental periosteum, etc. While this tissue performs the 
 functions of a periosteum for the bone of the alveolus, it differs in struc- 
 ture from the periosteum in any position, so that any name including 
 the word periosteum or implying a double membrane should be avoided. 
 
 The peridental membrane belongs to the class of fibrous membranes, 
 and is made up of the following structural elements: (1) Fibers. (2) 
 Fibroblasts. (3) Cementoblasts. (4) Osteoblasts. (5) Osteoclasts. 
 (6) Epithelial structures which have been called the glands of the 
 peridental membrane. (7) Bloodvessels. (8) Nerves. (9) Lymphatics. 
 
 The peridental membrane performs three functions: a physical 
 function, maintaining the tooth in relation to the adjacent hard and 
 soft tissues; a vital function, the formation of bone on the alveolar 
 
 1 Noyes : Dental Histology. 
 
 2 Arey, L. B.: Origin, function and fate of the osteoblast. Am. Jour, of Anatomy, 
 February, 1920. 
 
PERIDENTAL MEMBRANE 
 
 99 
 
 wall and of cementum on the surface of the root; and a sensory 
 function, the sense of touch for the tooth being exclusively in this 
 membrane. 
 
 Ap -! 
 
 Fig. 61. — Diagram of the fibers of the peridental membrane: G, gingival portion; 
 Al, alveolar portion; Ap, apical portion. (From a photograph of a section from incisor 
 of sheep.) 
 
 The fibrous tissue of the membrane is of the white variety, and may 
 be divided into two classes, the principal fibers and the indifferent 
 
100 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 or interfibrous tissue. The principal fibers may be defined as those 
 which spring from the cementum and are attached at their other end 
 to the bone of the alveolar wall, to the outer layer of the periosteum 
 
 Fig. 62. — Longitudinal section of peridental membrane from young sheep, showing 
 fibers penetrating cementum: D, dentin; C, cementum, showing embedded fibers; F, 
 fibers running to outer layer of periosteum covering the alveolar process ; F', fibers running 
 to the bone at the border of the process; B, bone. (About 80 X.) 
 
PERIDENTAL MEMBRANE 
 
 101 
 
 covering the surface of the alveolar process to the cementum of the 
 approximating tooth, or become blended with the fibrous mat of the 
 gum supporting the epithelium. They were so called by Dr. Black, 
 not only because they form the principal bulk of the tissue, but they 
 also perform the principal function of the membrane, the support of 
 the tooth and surrounding tissues. The interfibrous tissue, also of the 
 white variety, but made up of smaller and more delicate fibers, is found 
 filling spaces between the principal fibers and surrounding and accom- 
 panying the bloodvessels and nerves, and contains the lymphatics. 
 
 Fig. 63. — Longitudinal section of the peridental membrane in the gingival portion: 
 D, dentin; A'', Nasmyth's membrane; C, cementum; F, fibers supporting the gingiva; 
 F^, fibers attached to the outer layer of the periosteum over the alveolar process; F^, 
 fibers attached to the bone at the rim of the alveolus ; B, bone. (About 30 X.) 
 
 For convenience of description and study, the peridental membrane 
 is divided into three portions: the gingival, that portion which sur- 
 rounds the root occlusally from the border of the alveolar process; 
 the alveolar, the portion from the border of the process to the apex 
 of the root; and the apical portion, surrounding the apex of the root 
 and filling the apical region (Fig. 61). 
 
 The principal fibers spring from the cementum, the cementoblasts 
 building up the matrix^ around them and then calcifying both matrix 
 and fibers, in this way implanting their ends into the siuface of the 
 root. In Fig. 62 the fibers are seen passing through the last-formed 
 
102 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 layer of cementum. In most positions the fibers as they spring from 
 the cementum appear as well-marked bundles of fine fibers. A short 
 distance from the surface of the root they break up into smaller bundles, 
 which interlace and are reunited into larger bundles, to be attached at 
 their other extremity to the bone, cementum, or fibrous tissue. 
 
 To arrive at an understanding of the arrangement of the fibers of the 
 peridental membrane, they must be studied in both longitudinal and 
 transverse sections. In longitudinal sections of the membrane in the 
 gingival portion (Fig. 63) the fibers springing from the cementum at 
 the gingival line pass out for a short distance at right angles to the 
 long axis of the tooth and then bend sharply to the occlusal^ passing 
 into the gingiva to support it and hold it closely against the neck of the 
 tooth. These fibers are most numerous on the lingual side, where food 
 is brought against the gingiva with force in mastication and tends to 
 crush it down. In the middle of the gingival portion the fibers pass 
 out at right angles to the axis and are blended with the fibrous mat of 
 the gum on the labial and lingual sides, or are attached to the cementum 
 of the adjoining teeth on the approximate sides. A little farther from- 
 the gingival line the fibers are inclined slightly apically, passing over 
 the border of the process to be attached to the outer layer of the peri- 
 osteum. These fibers are especially large and strong and form what has 
 been called the ligamentum circulare. Just at the rim of the alveolus 
 the fibers are inclined slightly apically and inserted into the bone, 
 forming the edge of the process. 
 
 In transverse sections of the membrane in the gingival portion 
 (Fig. 64) the fibers spring from the cementum in large bundles; at 
 the center of the labial surface they extend directly outward, breaking 
 up into smaller bundles, passing around bloodvessels and bundles of 
 fibers, and blending with the fibrous tissue supporting the epithelium. 
 Passing mesially and distally toward the corners of the root, the fibers 
 swing around laterally and pass to the cementum of the next tooth. 
 On the approximate sides the fibers suddenly divide into smaller 
 bundles, which wind in and out around bloodvessels, and bundles of 
 fibers which pass into the gingiva and are reunited into large bundles 
 to be inserted into the cementum of the next tooth. On the lingual 
 side the arrangement is like that of the labial, except that the distance 
 to which the fibers of the membrane can be followed before they are 
 lost in the fibrous mat of the gum is usually greater than on the labial. 
 
 In the occlusal third of the alveolar portion of the membrane the 
 fibers pass, at right angles to the axis of the tooth, directly from the 
 
 1 In describing the direction and inclination of peridental membrane fibers, they are 
 always traced from the cementum to the bone, the angle with the horizontal plane being 
 formed at the surface of the cementum. 
 
PERIDENTAL MEMBRANE 
 
 103 
 
 Fig. 64. — -Transverse section of the peridental membrane in tlie gingival portion (from 
 sheep): E, epithelium; F, fibrous tissue of gum; B, point where peridental membrane 
 fibers are lost in fibrous mat of the gum ; P, pulp ; F', fibers extending from tooth to tooth. 
 (About 30 X.) 
 
 Fig. 65. — Fibers at the border of the alveolar process (from sheep): D, dentin; 
 C, cementum; F, fibers extending from cementum to bone; Bl, bloodvessel; 5, bone. 
 (About 80 X.) 
 
104 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 Pd 
 
 Cm 
 
 y -' ■ y-' 
 
 Al 
 
 
 
 ;A '■■■ 
 
 *S.. 
 
 lV: 
 
 
 ''^J 
 
 s- 
 
 
 *i 
 
 ■ M-^. 
 
 Al 
 
 YiG 66 —Transverse section of the peridental membrane in the occlusal third of the 
 alveolar portion (from sheep): ikf, muscle fibers; Per, periosteum; AZ, bone of the 
 alveolar process; Pd, peridental membrane fibers; P, pulp; D, dentm; Cm, cementum. 
 
PERIDENTAL MEMBRANE 105 
 
 cementum to the bone. In this position the fibers are large and do not 
 break up into smaller bundles, but the original fibers can be followed 
 uninterruptedly from the cementum to the bone (Fig. 65). In the 
 middle third the fibers are inclined occlusally, and this inclination 
 increases as the apical third is approached. In the apical third the 
 inclination is greatest, and the fibers as they arise from the cementum 
 are very large and break up into fan-shaped fasciculi as they pass 
 across to the bone. In the apical portion the fibers radiate from the 
 apex in all directions across the apical region and spread out in fan- 
 shaped bundles like those in the apical third of the alveolar portion. 
 
 In a transverse section near the border of the alveolus (Fig. 66), at 
 the center of the labial surface of the root, the fibers are seen to extend 
 directly out from the surface of the root to the bone of the process, 
 except where they are diverted to pass around bloodvessels. Passing 
 around distally at the corner of the root, the fibers swing laterally so 
 as to be almost at a tangent to the surface of the root, and are inserted 
 much farther to the distal on the wall of the alveolus. A similar 
 arrangement is noticed at the other corners of the root, though these 
 tangential fibers are usually more marked at the distal than at the 
 mesial corners. 
 
 Studying the arrangement of the fibers with reference to the physical 
 function of the membrane, it is seen to be the best that could be devised 
 to support the teeth against the force of mastication and to support 
 the tissues about them. In the gingival portion the fibers passing from 
 tooth to tooth form the foundation for the gingivae between the teeth 
 filling the interproximate spaces; so that if these fibers are cut off from 
 the cementum, by extending a crown band too far, or by the encroach- 
 ment of calculary deposits beginning in the gingival space, the gingivus 
 drops down and no longer fills the interproximate space. In the 
 alveolar portion the fibers at the border of the process and those at 
 the apex of the root together support the tooth against lateral strain, 
 while those in the rest of the alveolar portion are so arranged as to 
 swing the tooth in its socket and support it against the force of occlu- 
 sion (see Fig. 61). As seen from the transverse section, the fibers at 
 the occlusal third of the alveolar portion are so arranged as to support 
 the tooth against forces tending to rotate it in its socket. 
 
 Cellular Elements of the Membrane. — The fibroblasts are spindle- 
 shaped or stellate connective-tissue cells which are found between the 
 fibers as they are arranged in bundles. In sections stained with hema- 
 toxylin they take the stain deeply, and the fibers, which are unstained, 
 are differentiated by the cells lying in rows between them. The number 
 of fibroblasts in the membrane decreases with age. They are large 
 and numerous in the membrane of a newly erupted tooth, and com- 
 
106 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 paratively small and few in the membrane around an old tooth. This 
 is characteristic of fibroblasts in other positions. The fibroblasts are 
 shown as they appear in a hematoxylin-stained section with low 
 powers in Fig. 67, which gives part of the membrane in the gingival 
 
 Fig. 67. — Fibers and fibroblasts from transverse section of membrane: F, fibers cut 
 transversely; F^, fibers cut longitudinally, showing fibroblasts. (About 80 X.) 
 
 portion between two teeth. The cells are seen as spindle-shaped dots 
 which mark out the fibers; at F they are seen in a position where the 
 fibers are cut transversely. While these cells perform the same func- 
 tion for the cementum as the osteoblasts do for bone, they are in form 
 very different from the osteoblasts. The cementoblasts are always flat- 
 
 FlG. 
 
 -Cementoblasts. (Drawing by Dr. Black.) 
 
 tened cells, sometimes almost scale-like, and when seen from above are 
 very irregular in outline. This irregularity of outline is caused by the 
 cells fitting around the attached fibers of the membrane so as to cover 
 the entire surface of the cementum between the fibers. Fig. 68 from 
 
PERIDENTAL MEMBRANE 
 
 107 
 
 a drawing by Dr. Black shows several cementoblasts as seen when 
 isolated by teasing. The cementoblasts have a central mass of proto- 
 plasm containing an oval nucleus, and short irregular processes which 
 fit around the fibers as these spring from the surface of the cementum. 
 Fig. 69 shows them in section perpendicularly to the surface of the root, 
 where they are crowded between the fibers. The cementoblasts often 
 have processes projecting into the cementum like those from the 
 osteoblast, but processes projecting into the membrane have never 
 been demonstrated. 
 
 Fig. 69. — Transverse section, showing the cellular elements: Fh, fibroblasts; Ec, epithe- 
 lial structures; Ch, cementoblasts; Cm, cementum; D, dentin. (About 900 X.) 
 
 In the formation of the cementum occasionally a cementoblast be- 
 comes enclosed in the formed tissue filling one of the lacunae, in which 
 position it becomes a cement corpuscle. 
 
 The osteoblasts of the membrane cover the surface of the bone, 
 forming the wall of the alveolus, lying between the fibers which are 
 built into the bone. In form and function they are like the osteoblasts 
 in attached portions of the periosteum. They form bone around the 
 
108 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 ends of the peridental membrane fibers, building them into the sub- 
 stance of the bone. The bone thus formed over the wall of the alveolus 
 
 HB 
 
 PdB 
 
 Per 
 
 Fig. 70. — Border of growing process : Cm, cementum ; Pd, peridental membrane ; Pd.B, 
 solid subperidental and subperiosteal bone with imbedded fibers; Ms, medullary space 
 formed by absorption of the solid bone; H.B, Haversian-system bone without fibers; Per, 
 periosteum. (About 50 X.) 
 
PERIDENTAL MEMBRANE 
 
 109 
 
 is like the solid subperiosteal bone, and is penetrated throughout its 
 thickness by the imbedded fibers; but, as with the subperiosteal bone, 
 it is constantly being penetrated by perforating canals, the solid bone 
 being removed by resorption and rebuilt in bone with Haversian sys- 
 
 PdM 
 
 PdB 
 
 HB 
 
 Fig. 71. — Penetrating fibers in bone: PdM, peridental membrane; Oh^, osteoblasts of 
 peridental membrane; Ob^, osteoblasts of medullary space; PdB, solid subperidental and 
 subperiosteaV bone with embedded fibers; Ms, medullary space formed by absorption of 
 the solid subperidental bone with embedded fibers; H.B, Haversian-system bone without 
 fibers built around the medullary space. (About 200 X.) 
 
 terns. This process is shown in Fig. 70, a section through a growing 
 portion of the process around a permanent tooth. A higher power 
 (Fig. 71) shows the penetrating fibers and the formation of Haversian- 
 system bone without fibers, in the body of the process. 
 
 The osteoclasts, or myeloplaques, are bone-destroying cells (Fig. 
 
110 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 72) ; they act not only upon bone, but also upon cementum and dentin. 
 They are oval cells, often as much as 30 microns in diameter, and con- 
 tain many nuclei — from two or three to fifteen or twenty. They are 
 often called giant cells. The osteoclasts are not constantly found in 
 the membrane, but make their appearance whenever calcified tissues 
 are to be destroyed. In order that they may act upon a tissue they must 
 lie in contact with its surface, and therefore the first step in absorption 
 of the peridental membrane is the cutting off of the fibers imbedded 
 
 Fig. 72. — -Osteoclast absorption of bone over permanent tooth: Oc, osteoclasts; B, bone 
 of crypt wall; F, fibrous tissue of follicle wall; A, ameloblasts. (About 62 X.) 
 
 in the bone or cementum. Where the osteoclasts act upon the surface 
 of the tissue they produce bay-like excavations, in which they lie, and 
 which are known as Howship's lacunae. These excavations are shown 
 in Fig. 73, though the osteoclasts have disappeared. In Fig. 74, from 
 a ground section, the basin-like excavations are shown filled with 
 newly-formed cementum, thus leaving in the tissue the record of an 
 absorption repaired. In absorption of the roots of the temporary teeth 
 the osteoclasts are found not only in the membrane and attacking the 
 
PERIDENTAL MEMBRANE 
 
 111 
 
 surface of the root, but all through the medullary spaces in the bone, 
 removing the temporary alveolar process. 
 
 Fig. 73.— Root of a temporary mcisor, showing absorption and rebuilding of cementum 
 Urom sheep): G, gingiva; D, dentin -Cm, cementum; Ah, absorption cavity, showing 
 Mowship s lacunae; Cm}, newly-formed cementum. (About 50 X ) 
 
 When absorption is going on at one place on the surface of a root a 
 compensating formation of cementum is going on at another, so that 
 
112 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 not all of the fibers of the membrane are cut off. This is illustrated by 
 sections of temporary teeth that are read}' to be shed (Fig. 75) } 
 
 Fig. 74. — ^Record in the calcified tissue of an absorption repaired: D, dentin; Cm, cemen- 
 tum filling absorption cavity. (About 40 X.) 
 
 Epithelial Structures of the Membrane. — The peridental membrane 
 contains cellular structures of epithelial character which are so con- 
 spicuous that they demand consideration though their nature and 
 origin are not as yet fully understood. 
 
 Fig. 75. — Section showing absorption of the tooth of a sheep: a, cementum; b, osteo- 
 clasts in cementum and dentin; c, osteoclast in the peridental membrane. 
 
 These structures were first well illustrated and described by Dr. 
 Black, in his work on the periosteum and peridental membrane, in 
 
 1 Absorption of the Roots of Teeth, by Newton G. Thomas, Cosmos, 1920. 
 
PERIDENTAL MEMBRANE 
 
 113 
 
 Fig. 76. — Diagram of glands of peridental membrane. (Black.) 
 
 Fig. 77. — ^Epithelial structures of the peridental membrane (from sheep) : Fh, fibro- 
 blasts; Ec, epithelial structures; Ch, cementoblasts ; Cm, cementum; D, dentin. (About 
 468 X.) 
 
114 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 1887, and were called by him the glands of the peridental membrane. 
 About the same time von Brunn^ described what are probably the same 
 structures, and which he regarded as embryonal remains of the inner 
 layer of the enamel organ, which he described as growing down over 
 the surface of the root. These structures appear as cords of epithelial 
 cells arranged in the form of a network winding between the fibers of 
 the membrane, very close to the cementum and surrounding the root 
 
 Fig. 78. — Epithelial structures (from sheep): Fb, fibroblasts; Ec, epithelial structures; 
 Cb, cementoblasts ; Cm, cementum; D, dentin. (About 700 X.) 
 
 almost to the apex. This arrangement is illustrated in Fi^. 76, a dia- 
 gram by Dr. Black. The meshes of the net are close in the gingival 
 portion of the membrane, but grow more and more open in the alveolar 
 portion. They are not confined to the membranes of young teeth or 
 the temporary dentition, as Dr. Black has shown them in the mem- 
 brane of a tooth from a man seventy years old, though, like all of the 
 
 1 Archiv. f. mikros. Anat., 1887. 
 
PERIDENTAL MEMBRANE 
 
 115 
 
 cellular elements of the membrane, they become less numerous as age 
 advances. These structures are especially well shown in the mem- 
 branes of the pig and sheep. Fig 77 shows their appearance in a 
 transverse section of the root of an incisor of a sheep; here they swing 
 out from the surface of the cementum and back again in loops, winding 
 in and out among the fibers. Studied with higher powers (Fig. 78), 
 they are seen to be made up of epithelial cells with large oval nuclei 
 which react to the characteristic epithelial stains. They are arranged 
 
 Fig. 79. 
 
 -Epithelial structures: Ec, epithelial cord, apparently showing a lumen; Ch, 
 cementoblasts; Cm, cementum; D, dentin. (About 500 X.) 
 
 in cords, though sometimes what seems to be a lumen of a gland tubule 
 can be found (Fig. 79). The cords are invested with a delicate base- 
 ment membrane, but no special relation to bloodvessels has been 
 demonstrated. The attempt to show their connection with the surface 
 epithelium has thus far failed. As the gingiva is approached (Fig. 80), 
 they seem to swing out from the surface of the root and are lost between 
 the projections of the epithelium lining the gingival space. There is 
 evidence that these structures are, at least in some cases, of importance 
 as the primary seat of pathologic conditions of the membrane. 
 
116 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 Fig. 80. — Longitudinal section: Ej^, epithelium lining lhe gingival spacf; (Ig, gingival 
 gland, so called; D, dentin; A'', Nasmyth's membrane; Du, duct-like structure stretching 
 away toward the gingiva from the epithelial cord, seen at Ec; Cm, cementum, separated 
 from the dentin by decalcification. (About 50 X). 
 
PERIDENTAL MEMBRANE 
 
 117 
 
 Bloodvessels and Nerves of the Membranes. — Bloodvessels. — The 
 
 blood-supply of the peridental membrane is very abundant. Several 
 vessels enter the membrane from the bone in the apical region. These 
 arteries branch and divide, forming a rich network, from which the 
 capillary vessels are given off. The arterial network is constantly 
 receiving vessels which enter the membrane through Haversian canals 
 
 Fig. 81. — Unstained section, showing lymph capillaries of the tooth side of the 
 gingivae and their drainage through the ligamentum circulare to the peridental mem- 
 brane. 
 
 opening on the wall of the alveolus, and in this way the size of the 
 vessels passing occlusally is maintained. Arterial vessels also enter the 
 membrane over the border of the process. This double or triple 
 supply of the membrane is important, as it maintains the health of 
 the membrane when the supply entering through the apical region 
 is entirely cut off by alveolar abscess. While the arterial supply of 
 the membrane is very rich, the capillaries in the membrane are com- 
 paratively few. This is, however, a characteristic of connective-tissue 
 membranes. 
 
118 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 Fig. 82. — Transverse section of the peridental membrane; showing injected 
 lymphatic vessels (oc, 3; obj., 16 mm.; reduced about one-tenth). 
 
 -» 
 
 
 
 
 •- ^ 
 
 :^>;^^ 
 
 Fig. 83. — Transverse section just at the apex of the root, showing injected lymphatic 
 vessels in the peridental membrane and in the canals passing to the pulp (oc, 2; obj., 
 16 mm.; reduced about one-third). 
 
PERIDENTAL MEMBRANE 
 
 119 
 
 Space will not permit an extended description of the lymphatics 
 of the dental region; for this the reader is referred to other and more 
 extended treatises. 
 
 The mucous membrane of the mouth, lips, cheeks, alveolar process 
 and gums gives rise to a very rich network of lymphatic capillaries 
 which drain through a limited number of trunks to the sub-mental, 
 the submaxillary and the upper group of deep cervical lymph glands. 
 The capillaries of the labial and buccal slopes of the alveolar process 
 including those from the outer slopes of the gingivae pass to the reflec- 
 tion of the soft tissue from the bone to the lip or cheek. On the lingual 
 side, in the upper arch, they pass obliquely backward and to the upper 
 
 Fig. 84. — Injected lymph vessels in the inferior dental canal. 
 
 group of deep cervical nodes; in the lower, those from the incisal 
 region probably pass to the submental nodes, while those from the 
 molar and bicuspid region join the collecting trunks from the lateral 
 portions of the tongue. 
 
 The course of this drainage is important in the effect of radical 
 curetting of infected areas about the teeth. 
 
 The first injections of the lymphatics of the peridental membrane 
 have been made in the last year or two. As a result of this work, the 
 following statements can be made with some positiveness. The lym- 
 phatics arising in the papilla under the epithelium on the buccal and 
 lingual slopes of the gingivae pass outside of the periosteum over the 
 
120 DENTAL HISTOLOGY, WITH REFERENCE TO DENTISTRY 
 
 alveolar process to a wreath of collecting trunk at the reflection of 
 the soft tissues from the bone to the lips or cheek. The lymphatics 
 arising in the papillee of the connective tissue supporting the epithe- 
 lium of the gingival space pass close to the cementum, penetrate the 
 ligamentum circulare and extend in the interfibrous tissue with the 
 bloodvessels and nerves through the peridental membrane to the apex 
 of the root. They anastomose with the vessel in the bone of the alveo- 
 lar process. At the apex of the root they receive the vessels from the 
 dental pulp and pass through the bone to the inferior dental or infra- 
 orbital canal. They have been traced emerging from the anterior 
 openings of these canals, and to the submaxillary lymph nodes, but it 
 
 Fig. 85 
 
 is probable that from the region of the second and third molars they 
 emerge from the posterior openings of these canals and pass to the 
 upper groups of deep cervical nodes. The course in the incisor region 
 is also not positively determined. It is probable that some of the 
 vessels from the low^er incisors drain through the submental nodes and 
 those from the upper incisors probably become superficial on the outer 
 surface of the maxilla or on the floor of the nose. In the dog's head 
 illustration, injections were made only in the canines and first molars 
 and the injecting fluid was followed throughout its course to the sub- 
 maxillary nodes. 
 
 Nerves. — The nerves of the peridental membrane have not been 
 sufficiently studied to be described in detail. Six to eight medullated 
 
PERIDENTAL MEMBRANE 121 
 
 nerve trunks enter the apical region in company with the bloodvessels, 
 and they receive other trunks through the wall of the alveolus and over 
 the border of the process, but the manner of their distribution and the 
 nature of their endings are not known. 
 
 The Changes which Occur in the Membrane with Age. — ^When a 
 tooth is erupted the roof of the bony crypt in which it was enclosed 
 in the body of the bone is removed by absorption and the crown 
 advances through the opening. The diameter of the alveolus at that 
 time is, therefore, greater than the greatest diameter of the crown, and 
 
 Fig. 86. — -Young and old membranes (from sheep): D, dentin; Cm, cementum; Cm^, 
 thickening of cementum to attach fibers at the corner; Pd, peridental membrane; 5, bone 
 forming the wall of the alveolus; P, pulp. (About 80 X.) 
 
 the peridental membrane which fills the space is very thick. By the 
 formation of bone on the wall of the alveolus and the formation of 
 cementum on the surface of the root the thickness of the membrane is 
 reduced. In the young membrane most of the large bloodvessels are 
 found in its outer half, forming a rather defined vascular layer near its 
 center. In the old membrane most of the bloodvessels are found very 
 close to the surface of the bone, often lying in grooves in its surface. 
 Both young and old membranes are illustrated in Figs. 85 and 86, which 
 are taken from the temporary teeth of a sheep, one just after eruption 
 and the other shortly before the time of shedding. 
 
CHAPTER III. 
 
 PREVENTIVE DENTISTRY. 
 
 By RUSSELL W. BUNTING, D.D.Sc. 
 
 The term preventive dentistry has been given a very flexible inter- 
 pretation and has included a wide range of operative and prophylactic 
 procedures. Not only has it been applied to the prevention of dental 
 disease, but also to the prevention of general diseases which may result 
 from dental or oral infection. As a result of the different viewpoints 
 of writers who have dealt with this subject, various statements and 
 opinions have appeared which are so contradictory and confusing that 
 in the minds of many the exact meaning and significance of the term 
 preventive dentistry is not clear. Strictly speaking, preventive dentis- 
 try should consist of the employment of those measures which will 
 tend to prevent dental and oral diseases; but, as will be pointed out 
 later, the successful accomplishment of this object will effectually 
 prevent many general bodily diseases, so that in the realization of one 
 the other is attained. Preventive dentistry in its broadest sense, 
 therefore, aims not only at the prevention of dental diseases, but also at 
 the prevention of any general disorders which might arise as a result of 
 dental disease. These two conceptions are therefore so closely related 
 that one may not well be considered apart from the other. 
 
 In a consideration of our present knowledge regarding the prevention 
 of dental disease, it must be admitted at the outset that as yet no 
 absolute methods of control have been found by which an immunity 
 to any of the special dental affections may be attained. No panacea, 
 specific drug, or vaccine has been discovered which will exert a definite 
 protective action against dental diseases after the manner of typhoid 
 and diphtheria immunization. Although dental diseases are not abso- 
 lutely preventable, it may be said that they are partially or relatively 
 preventable, for by the employment of certain measures the occur- 
 rence of dental disease may be decreased and in many cases entirely 
 eliminated. And further, dental disease may be permanently arrested 
 if taken early in its course, whereby the extent of the lesion is limited 
 and serious destruction of the tissue prevented. 
 
 Preventive dentistry therefore may be said to consist of the employ- 
 ment of all those measures which tend to decrease the inception of 
 oral diseases and in the early application of operative procedures to 
 arrest the progress of lesions which have already occurred. In many 
 
 (122) 
 
PREVENTIVE DENTISTRY 123 
 
 respects the practice of preventive dentistry is not unlike the present 
 methods of preventing tuberculosis. Preventive medicine has dis- 
 covered no infallible cure for this dread malady, but has found that 
 the observance of proper life conditions and hygiene will, as a rule, 
 successfully prevent its occurrence even in individuals who have a 
 tendency toward phthisis. And in those cases in which the disease has 
 already begun, if taken in the early stages, the lesion may be checked 
 and healing effected. At the present time, the greatest success in the 
 prevention of dental diseases and tuberculosis lies in the employment 
 in each case of those specific measures of partial prevention which tend 
 to inhibit these diseases. It is to the application of these measures 
 of prevention to dental diseases and their systemic effects that this 
 chapter is devoted. 
 
 The practice of dentistry and medicine in the past was limited to the 
 treatment of diseases which had already manifested themselves and to 
 the repair of tissues which had been damaged by disease or injury. 
 But in recent years both professions have recognized their inability to 
 maintain the health of the human race by curative measures alone and 
 have come to see that there is great need for more effective means of 
 disease prevention. The study of methods by which diseases may be 
 prevented has become, therefore, an important branch of dental and 
 medical practice. 
 
 In the field of dentistry, the greatest thought and energy have been 
 directed in the past toward the perfection of various operative pro- 
 cedures by which the dental tissues, which have been damaged by 
 disease, might be repaired, and their functions restored. To this end 
 dental technics have been developed to such a high degree of perfection 
 that extensive restorations and the rehabilitation of badly diseased 
 mouths have been made possible. Today, therefore, by virtue of 
 modern dental art, many cases which formerly would have been 
 considered hopeless and condemned to the forceps may be rebuilt and 
 restored to masticatory efficiency and esthetic appearance. In this 
 manner dentistry has endeavored to play her part in the general 
 scheme of public health. 
 
 But in the light of recent developments in medical science grave 
 questions have arisen as to the safety of many operative procedures in 
 dental practice. This question was most forcibly brought to our atten- 
 tion by Wm. Hunter,^ of England in a series of papers in which he 
 severely arraigned the practice of dentistry, especially the so-called 
 "American Dentistry" as carried on in England. He stated that many 
 dental restorations, such as gold fillings, crowns, and bridges cover and 
 
 1 Hunter, Wm. : The Role of Sepsis and Antisepsis in Medicine, London Lancet, 
 January 14, 1911; Dental Cosmos, July, 1918, p. 585. 
 
124 PREVENTIVE DENTISTRY 
 
 conceal septic material about the roots of teeth, and that these infec- 
 tions constitute a grave menace to the health of the individual. He 
 believed that these infectious organisms might enter the blood stream, 
 be distributed throughout the body, and give rise to a wide range of 
 disturbances, namely, affections of the digestive tract (ulcers, colitis, 
 enteritis, etc.), of the glands (adenitis), of the blood (anemia, and 
 septicemia), of the joints (arthritis), of the kidneys (nephritis), and of 
 the nervous system. It was the opinion of Hunter that these septic 
 teeth were retained in place and the areas of infection hidden for many 
 years by reason of faulty and ill-advised dental operations when, for 
 the good of the patient, they should have been extracted or allowed to 
 exfoliate. He inferred that the poor people who could not afford such 
 dental restorations were more fortunate than those who could and did 
 have them because in their case the diseased roots would tend to be 
 exfoliated and the peridental infections might escape to the surface 
 rather than be confined in the tissues and enter the circulation. 
 
 These criticisms at first aroused a storm of resentment and protest 
 on the part of the dental profession. They believed that the charges 
 made were unwarranted and unjust and they could not conceive the 
 possibility that skillful works of dental art by which diseased mouths 
 had been made serviceable and comfortable could be anything but 
 beneficial to the individual. But because of the interest which was 
 aroused in the question, extensive and careful studies of the peridental 
 tissues were made to determine the prevalence and extent of peridental 
 infection. By the wide application of improved methods of dental 
 roentgenographic technic, a great mass of data has been gathered and 
 reported, the results of which have been so startling that they have 
 revolutionized many of our previous concepts. For a clear under- 
 standing of these findings the reader is referred to the original reports 
 of investigation, a partial list of which is appended.^ The data which 
 
 1 Rosenow E. C: Elective Localization of Streptococci, Jour. Am. Med. Assn., 
 November 13, 1915, p. 1687. 
 
 Rosenow, E. C: The Relation of Dental Infection to Systemic Disease, Dental 
 Cosmos, May, 1917, p. 485. 
 
 Rosenow, E. C: The Pathogenesis of Focal Infections, Jour. Nat. Dent. Assn., 
 February, 1918, p. 113. 
 
 Billings, Frank: Focal Infection, Jour. Am. Med. Assn., September 12, 1914, p. 899. 
 
 Mayo, C. H. : Constitutional Diseases Secondary to Local Infections, Dental Review, 
 April, 1913, p. 281. 
 
 Mayo, C. H. : Mouth Infection as a Source of Disease, Dental Summary, January, 
 1915, p. 1. 
 
 Mayo, C. H.: The Control of Focal Infections, Dental Cosmos, November, 1918, 
 p. 963. 
 
 Hartzell, T. B., and Henrici, A. T. : Report of Mouth Infection Research Corps of 
 the National Dental Association, Official Bulletin, Jour. Nat. Dent. Assn., October, 1914, 
 p. 48; 1915, p. 333; November, 1916, p. 333; May, 1917, p. 477. 
 
 Black, A. D.: Roentgenographic Studies of Tissues Involved in Chronic Mouth 
 Infections, Jour. Am. Med. Assn., October 19, 1918, p. 1279. 
 
 Fischer, Martin: The Relation of Mouth Infection to Systemic Disease, Dental 
 Summary, August, 1915, p. 607. 
 
PREVENTIVE DENTISTRY 125 
 
 were obtained by these and other students of the subject clearly revealed 
 the fact that peridental infection and sepsis exist about the roots of 
 teeth far more commonly than previously had been suspected. Large 
 and small areas of necrotic change were discovered in the bone and 
 peridental membrane about the apices of devitalized teeth, as well 
 as deep septic pockets about the roots of pyorrhetic^ teeth. Upon 
 examination these areas were found to contain pure or mixed cultures 
 of streptococci, staphylococci, pneumococci and other organisms, 
 among which the Streptococcus viridans appeared to be especially 
 prominent. Many of these septic areas produced no pain and gave no 
 outward evidence of their presence other than that shown by the 
 roentgenogram. Clinical histories revealed that many of these 
 infections had in all probability existed for months or years about 
 the apices of devitalized teeth, the root-canals of which were incom- 
 pletely filled, and in deep pockets about loose pyorrhetic teeth which 
 had been held in place by ligatures or bridge work. These peridental 
 infections have been shown to occur with astonishing frequency 
 especially where the state of oral hygiene and the method of treating 
 and filling root-canals of teeth have been of an indifferent character. 
 In tabulations made in the large clinics of the great cities, it was found 
 that over 75 per cent, of the non-vital teeth were septic. It is true 
 that these data were taken from patients coming from the poorer classes 
 for whom dental services had been of an inferior grade, but it was also 
 found that even among the patients of the most skilled operators deep 
 infections occurred with great frequency. 
 
 The question then arose as to the significance of these peridental 
 infections and their possible relationship to general health. It was 
 noted clinically that many patients who had considerable oral sepsis 
 were also suffering from certain general disturbances. These disturb- 
 ances seemed to be of wide range but the most prominent and frequent 
 in occurrence were joint affections (arthritis) and heart lesions (endo- 
 carditis and myocarditis). Rosenow and others^ isolated bacterial 
 cultures from the infected peridental tissues and injected them into 
 animals with the result that in many cases the animals showed bodily 
 disturbances similar to those of the patient from whom the cultures 
 were taken. That is, certain organisms, especially the Streptococcus 
 viridans, taken from peridental infections and injected into the circula- 
 tion of an animal had the ability to localize in the joints, heart, or other 
 tissues of the animal and produce pathologic disturbance. Although 
 the theory which Rosenow advanced as to the method by which these 
 bacteria became localized (elective localization) has not received uni- 
 
 1 For use of term pyorrhea, see Chapter XIII. - Loc. cit. 
 
126 PREVENTIVE DENTISTRY 
 
 versal corroboration, the fact remains that septic material taken from 
 the tissues about the teeth and injected into animals will produce in 
 them general disturbances of bodily health, which in many instances, 
 are closely parallel to the clinical findings of the patient from whom the 
 infectious organisms were taken. All septic areas about the teeth are 
 therefore looked upon today as potential foci of general infection from 
 which organisms and their products may and frequently do spread by 
 way of the lymph and blood-stream to the various tissues and organs of 
 the body. Clinical observation teaches us that not every infection of the 
 peridental tissues gives rise to systemic disorders, for in many instances 
 these tissues are seriously infected while the general health is seemingly 
 unimpaired. In cases of this kind the local tissue reactions are so 
 complete that they effectually confine the infectious organisms and 
 prevent their spread in the general circulation. But there is always 
 the possibility that such localized infections may break through the 
 protective defenses at some future time, especially during a general 
 decline of body reactions and tissue defense. 
 
 At the present time, therefore, there remains little room for doubt 
 that systemic infection may, and frequently does, arise from localized 
 areas of sepsis about teeth, many of which may give no evidence of their 
 presence other than that shown by the roentgenogram. Consequently 
 dental operative procedures and oral sepsis have come to be recognized 
 by both the dental and medical professions as matters of great signi- 
 ficance to general health. No longer may the mouth be considered as a 
 separate and independent part of the body, but rather, it must be viewed 
 as an important and strategic avenue by which pathogenic bacteria 
 may gain entrance to the general circulation. 
 
 As a result of this newer conception of oral infection and the manifest 
 relationship of dental health to the general health, dentistry is confronted 
 with serious problems and responsibilities. Many dental operative 
 procedures which in the past have been considered safe and well-founded 
 are now known to be dangerous and often highly injurious to the health 
 of the individual. The question has arisen therefore, "What dental 
 procedures are safe and sane?" In answer to this question a very 
 careful study of all departments of dental practice which have a bearing 
 upon oral sepsis has been made with the view of proving the safety of 
 each operation and discarding from dental practice all those procedures 
 which are unsafe. Consequently, the viewpoint of practitioners of 
 dentistry has undergone such a radical change that tooth conservation, 
 which was formerly considered to be the matter of greatest importance, 
 has been superseded by, and made secondary to, the question of safety 
 in respect to oral sepsis and systemic infection. Already marked 
 changes have occurred in dental teaching and practice and it is reason- 
 
ORAL SEPSIS 127 
 
 able to expect that as our knowledge of oral sepsis shall be increased by 
 future study and research, further modifications will be made in opera- 
 tive dentistry to insure the safety of its procedures. It is today 
 generally conceded that fillings. cro\\Tis, and bridges should not be 
 placed on teeth which have septic areas about them and that all possible 
 means should be utilized to discover the presence of such infection 
 before beginning operative procedures. Severe lesions in the peridental 
 tissues either apical or pyorrheal are no longer treated with the hope 
 of cm'e, but on the contrary the affected teeth are extracted for the 
 safety of the patient. Indeed, there are many who claim that no 
 devitalized teeth should under any circumstance remain in the mouth, 
 believing that they always constitute a possible source of infection. 
 On the other hand, there are many others who believe that it is possible 
 to fill the root canals of devitalized teeth in a manner that is above 
 reproach and are attempting in every way to perfect the technic of this 
 operation. Operative dentistry then is undergoing a change in its 
 policies by which it is making an honest attempt to meet the new 
 situation to the end that its procedures may be safe and sane as regards 
 dental sepsis and systemic involvement. And not until all dental 
 operations shall be so ordered that the possibility of oral infection is 
 minimized or removed will dentistry fulfill her duty as a guardian of 
 public health or be fully accepted as a benefit to mankind. 
 
 ORAL SEPSIS. 
 
 The term oral sepsis is used to denote a relative state of mouth infec- 
 tion. The oral cavity is never sterile but, on the contrary, continually 
 harbors various forms of bacteria, pathogenic and non-pathogenic, in 
 health as well as in disease. These organisms thrive among the oral 
 secretions and retained foodstuffs, living in s>Tabiotic relationship to 
 each other. In health, the mucous membrane presents an efficient and 
 continuous barrier against infectious organisms by which the mouth 
 bacteria are prevented from entering *the deeper underlying tissues. 
 As long, therefore, as the protection is complete, the oral micro- 
 organisms are segregated in the mouth cavity and the digesti^'e tract 
 and are of no apparent significance to the general health. Normally the 
 bacterial flora of the mouth leads a low-grade, saprophytic existence 
 quite independent of the body as a whole. But when, by reason of poor 
 mouth hygiene, quantities of food debris are retained about the teeth, 
 fermentations take place and the bacterial flora is greatly increased. 
 In such cases certain t^^es of organisms may attain a high degree of 
 virulence producing rapid and extensive fermentation thereby changing 
 
128 PREVENTIVE DENTISTRY 
 
 the bacterial picture of the oral cavity from a normal low-grade flora 
 to that of a vicious, harmful overgrowth of microorganisms capable of 
 destroying the protective mucous barriers of the mouth and invading 
 the deeper tissues. This latter state is known as oral sepsis. 
 
 The manifestations of oral sepsis present a wide range of variation 
 dependent upon the type or types of organisms which predominate 
 in the overgrowth, the quality of oral hygiene, and the general health 
 of the host. Clinically, two general classes may be distinguished, 
 namely acute and chronic. The former consists of open and manifest 
 infections which rapidly involve the mucous surfaces of the oral cavity. 
 They excite intense inflammatory reactions in the gums, the cheeks, 
 and the tongue accompanied by more or less ulceration and desquama- 
 tion of the superficial tissues. To these the general term stomatitis 
 is applied, which includes a wide range of ulcerative conditions depen- 
 dent upon the type of predominating organism and the severity of its 
 proliferation. As a rule, these acute infections run a rapid and virulent 
 course and the symptoms which they produce are so alarming that the 
 attention of the patient and the operator is readily attracted to them'. 
 When prophylactic and abortive treatment is applied they are promptly 
 controlled and the tissues usually return to normal within a few days. 
 
 Unlike the acute type, the chronic forms of oral sepsis are mild and 
 inconspicuous in their action. They consist in an overgrowth of 
 organisms which do not produce ulceration or active inflammatory 
 reactions in the tissues. Thriving upon the retained foodstuffs about 
 the teeth and in mucoid plaques in the gingival areas they set up a 
 chronic low-grade irritation in the gmn tissues, as a result of which 
 chronic inflammation and slow degenerations of the peridental tissues 
 ensue. By reason of the insidious manner of their growth these chronic 
 infections may be easily overlooked and frequently may only be 
 recognized by staining the teeth with a disclosing solution. Conse- 
 quently they may exist in a mouth unobserved for months or years and 
 slowly accomplish a progressive degeneration of the peridental tissues, 
 thereby gaining entrance to the underlying deeper structures. 
 
 Recent investigations have been directed toward a study of the 
 various organisms which are involved in the several t^-pes of oral 
 sepsis. It has been found that in the acute ulcerative types of infection 
 and in abscesses the predominating organisms are of a purulent, hemo- 
 lytic type which have the ability to destroy tissue rapidly with the 
 formation of pus. Among others Streptococcus pyogenes. Staphy- 
 lococcus pyogenes albus and aureus^ Bacillus pyocyaneus are com- 
 monly found. Against them intense inflammatory reactions are set 
 up in the tissue by reason of which their course is limited and their 
 activities confined. The active and purulent types of infection, there- 
 
ORAL SEPSIS 129 
 
 fore, being restrained by the protective powers of the tissues, as a rule, 
 do not tend to spread far from the original seat of inoculation. 
 
 In the subacute or chronic forms of oral sepsis the predominating 
 organisms are usually a non-purulent, non-hemolytic type among which 
 Streptococcus viridans occurs with the greatest frequency. Various 
 streptococcal strains, of which viridans is one form, may be demon- 
 strated in practically every case of non-purulent gingivitis and pyorrhea 
 and in the periapical affections known as granuloma. This type of 
 organism does not excite active tissue reactions but rather induces in 
 them progressive degenerations against which the tissues have little 
 power of self protection. There is, therefore, a tendency for these 
 chronic t^^pes of infection to infiltrate deeply into the tissues which 
 they attack and on gaining entrance to the bloodvessels of that region 
 they may be introduced into the general circulation. 
 
 When we view these two forms of oral sepsis in the light of their 
 significance to the general health, it becomes evident that they are not 
 of equal importance. In former times the purulent type of infection 
 was looked upon with the greatest concern, and indeed, the peridental 
 abscess, purulent forms of pyorrhea and active tissue ulcerations were 
 the only infections that were given any serious consideration. It was 
 recognized that these infections would in time produce marked and 
 often extensive degeneration of the local tissues and occasionally the 
 more severe types resulted in general septicemia. But more recently 
 we have come to have a greater fear of the insidious- forms of bacterial 
 invasion, namely, the non-purulent streptococcal group of organisms 
 which manifest a greater tendency to penetrate into the deeper tissues 
 and enter the general circulation. 
 
 The true significance of these two types of infection and the manner 
 of their action may be expressed in terms of tissue resistance. 
 Nature has built in every oral cavity a complete lining which offers 
 resistance to the entrance of all kinds of organisms into the underlying 
 tissues. It is only by injury to this mucous membrane, or the teeth, 
 that oral sepsis may gain entrance to the general circulation. And 
 when, either by accident or by bacterial erosion, a lesion has been made 
 in the protective covering, the infectious organisms meet in the tissues 
 a second line of defense which consists of all the protective reactions 
 of the bodily tissues; namely, phagocytosis, bacteriolysis, antitoxins, 
 granulation tissue, etc. By these reactions the tissues seek either to 
 overcome and destroy immediately the infectious organisms, or, failing 
 in this, to form a protective wall of granulation tissue about the septic 
 invader to limit its action and confine it to one locality. This wall 
 at first consists of masses of lymphocytes and leukocytes which have 
 rallied to the spot under the direction of chemotaxis, and many new 
 9 
 
130 PREVENTIVE DENTISTRY 
 
 and rapidly growing bloodvessels which afford a very rich and free 
 blood supply to the part. Later, if the tissues succeed in checking the 
 invasion, this limiting wall is organized into a more permanent line of 
 defense by the growth of connective-tissue fibers until the infectious 
 material is entirely enclosed in a fibrous tissu e sac. When this has been 
 accomplished, the bacteria, as a rule, are effectually confined, although 
 the possibility still remains that they, or their toxins, may make their 
 escape in limited quantities by way of the capillaries which enter and 
 leave the sac. But the tissue reactions which have just been described 
 are not always complete. They, in the first place, are dependent upon 
 the type of bodily health and general activity which the individual 
 possesses. When the general health is good the local reaction to 
 infection will be far more vigorous than when the vitality is low. In 
 the second place, as the local tissue reactions arise in response to 
 bacterial injury, the type of reaction which is produced will be deter- 
 mined largely by the type of invading organism. Against the acute 
 purulent types of infection the tissue reactions are high and, as a rule, 
 sufficient to check and control effectually the invader, while against 
 the non-purulent streptococcal type of infection the protective reactions 
 are usually weak and insufficient to check the penetration of the organ- 
 isms into the tissues and the circulation. It is therefore that type of 
 infection against which the protections are weak that is most to be 
 feared, inasmuch as even in healthy individuals the tissues are fre- 
 quently unable to combat it successfully, but are seemingly at the 
 mercy of the invader. 
 
 In a consideration, therefore, of oral sepsis in its relation to systemic 
 disease, we must recognize that those forms of infection which are low 
 grade and non-purulent are most to be feared, not only on account of 
 the inability of the tissues to combat them, but also because of the 
 fact that since they excite no active tissue reactions, their invasion is 
 insidious, almost imperceptible, and their presence may be overlooked 
 easily. It is then to the control of this type of infection that the 
 greatest attention should be given in the practice of preventive 
 dentistry. 
 
 In a study of methods by which these infections may be controlled, we 
 are led to consider the avenues by which the organisms break through 
 the protective defenses of the mouth : that is, the areas of the oral cavity 
 which are most susceptible to bacterial invasion and which, therefore, 
 should be watched most carefully. Practically all deep infections of 
 the oral tissues occur in one of two general localities; the one through 
 a carious defect in a tooth involving the pulp, and the pulp-canal and 
 thence to the periapical tissues; the other by way of the gingival 
 crevice about the neck of a tooth into the deeper peridental tissues. 
 
ORAL SEPSIS 
 
 131 
 
 So comprehensive are these two avenues of infection that could they be 
 successfully protected and closed, practically all danger of oral sepsis 
 would be eliminated and systemic disease from a dental source would 
 most effectually be prevented. It is therefore to the guarding of these 
 two gateways of infection that preventive dentistry must be directed. 
 The question next arises as to the manner in which these invasions 
 occur. In the first type we find that the initial step is a lesion in a tooth, 
 a carious cavity, which is laden wath infectious organisms charac- 
 teristic of the mouth flora. As soon as the pulp is exposed, these 
 
 Fig. 87 
 
 organisms promptly invade the pulpal tissue, through which they 
 pass out through the apex of the root to be implanted in the 
 periapical tissues. If the infection be purulent in tj^pe, an acute 
 abscess is formed, accompanied by pus and a severe inflammatory 
 reaction. If, however, the infection be low grade and non-purulent in 
 type, a mild tissue reaction will be set up and a gradual destruction of 
 tissue will be effected with little or no outward signs or symptoms in 
 evidence thereof. At the present time we do not fully understand the 
 significance of these lesions. In many cases it seems that the tissue 
 
132 PREVENTIVE DENTISTRY 
 
 is able to construct a fibrous tissue wall about the infection forming 
 a so-called granuloma. Upon examination these granulomata are 
 frequently found to be sterile, from which it is inferred that the organ- 
 isms which caused the lesion have been overcome by the bactericidal 
 properties of the surrounding tissues. But many of these non-purulent 
 lesions contain pneumococci and Streptococci viridans which may act 
 as potential foci of systemic infection. As we have at present no means 
 at hand by which we may distinguish clinically the dangerous from 
 the benign types, all granulomata must be viewed with suspicion. 
 
 The successful treatment and elimination of periapical infections are 
 not easily accomplished. As a rule they have invaded far beyond the 
 end of the root so that the treatment of these lesions through the 
 root-canals is uncertain and of doubtful value. For the most part, 
 surgical excision of the root and curettage of the infected bone through 
 the gum tissues (root resection or apicoectomy) is the only efficacious 
 manner of treating all such cases save perhaps the more incipient forms. 
 And, indeed, there are many who hold that no tooth, the root-end of 
 which has been seriously affected, should in any case be retained. 
 
 Every tooth therefore in which the pulp has died from bacterial 
 invasion, by accident, or by operative procedures, must be looked upon 
 as a possible source of infection. The difficulty of completely filling 
 tortuous root-canals and the ease with which infectious matter may be 
 introduced during the operation of cleansing and filling the root-canals 
 make the coefficient of error and the probability of subsequent infection 
 exceedingly high. 
 
 A study of roentgenograms of a large number of pulpless teeth 
 has demonstrated clearly that the most certain root-canal filling is a 
 living and healthy pulp. That is not to say that root-canals of such 
 a tooth cannot be filled safely, but the fact should be emphasized 
 that the successful filling of root-canals is an exceedingly difficult and 
 hazardous undertaking which should be attempted only under the most 
 favorable circumstances and performed with the most careful technic. 
 
 The handling of pulpless teeth and root-end infections is, therefore, 
 a difficult problem in dental practice. It is conceded, however, that 
 periapical infections seldom occur on teeth having vital pulps. If^ 
 therefore, the pulps of all teeth could be kept alive, the dangers of 
 periapical infection as well as the difficulties of root canal operations 
 would be eliminated. Going still further, we may say that the great 
 majority of pulps die, either directly or indirectly, from dental caries. 
 If then, we could either prevent caries or check its lesions before they 
 involve the pulp, practically all teeth might remain alive. It follows_, 
 therefore, that the absolute prevention and control of dental caries 
 would automatically result in the prevention of periapical abscesses 
 
PERIDENTAL AFFECTIONS 133 
 
 and granulomata with all their attending sequelae. It is then in the 
 prevention and control of dental caries that the greatest hope of suc- 
 cess lies, by closing the root-end route through which oral infections 
 may enter the general circulation. 
 
 PERIDENTAL AFFECTIONS. 
 
 Turning to the second order of dental infections, the peridental 
 type, we find somewhat different conditions prevailing. In the first 
 place, we observe that of all the mucous coverings of the mouth the 
 gingivae are most vulnerable to the attack of infectious organisms. 
 In all other portions of the mouth the mucous membrane with its 
 thickened epithelium offers a continuous protective barrier against 
 the entrance of infectious organisms. But in the process of erup- 
 tion of the teeth, holes are made in this membrane, one for each 
 tooth, which apertures persist as long as the tooth remains in 
 position. Nature attempts to protect the body at these places 
 and to close the door against the entrance of infection through them 
 by causing the borders of each opening to be drawn in tightly about 
 each tooth with the formation of a purse-like flap, the gingiva, 
 which normally hugs tightly about the neck of each tooth. On the 
 inner side of this gingival flap there is a shallow space between it and 
 the tooth, the gingival crevice, at the bottom of which the mucous 
 membrane is firmly attached to the pericementum by strong connective- 
 tissue fibers. In health these gingival tissues are thin, firm, and so 
 closely adapted to the teeth that they offer considerable resistance to 
 the entrance of infectious organisms. So effective is the gingival 
 attachment that as long as the tissues remain in perfect normality 
 they successfully protect the underlying tissues. But when masses of 
 infectious material remain for some time in close contact with the 
 gingivae, as in cases of faulty oral hygiene, or when they are disturbed 
 by the traumata of food, calculi, crowns, bridges, overhanging fillings, 
 etc., the gingivae are irritated and become inflamed. Because of the 
 fact that the gingival tissues have an end-circulation, it follows that 
 slight irritations may produce profound disturbances such as active 
 and passive congestion, thrombosis, and other inflammatory reactions. 
 In the event of any of these conditions, the health and normal function 
 of the gingivae are profoundly disturbed. No longer do these tissues 
 cling tightly about the teeth, but rather do they swell and become puffy, 
 their normal tone is lost and they fall away from the teeth. In this 
 manner the gingival crevice is opened to mouth infection and an 
 excellent opportunity is offered for the growth of infectious organisms. 
 The surrounding tissues also, being disturbed in their circulation and 
 
134 PREVENTIVE DENTISTRY 
 
 metabolism are often less able to combat these infectious invaders. 
 The result is that deep penetration of septic organisms takes place. 
 If the infection be of a purulent type, superficial ulcerations of the 
 gingival tissues are produced or the deeper peridental affections char- 
 acteristic of true pyorrhea are affected consisting of the formation of 
 a pocket along the side of the root of the tooth and the production 
 of pus. If the infection be non-purulent in type, a slow disintegra- 
 tion of peridental tissues may take place with the formation of pockets 
 on the lateral surfaces of the root in which no pus will be found. In 
 either case, the infectious organisms have passed the epithelial barrier 
 and have become firmly entrenched in the deeper tissues where they 
 are either confined by the local tissue reactions or spread through the 
 circulation to remote parts of the body. The early stages of this 
 process are known as gingivitis while all forms of deeper penetration 
 and tissue destruction are commonly referred to under the general 
 term pyorrhea alveolaris. 
 
 Much has been written regarding the cause, course, and effects of 
 the so-called pyorrhetic types of infection and a wide diversity of 
 opinion is expressed. At the present time, however, the more rational 
 students of the subject agree that all of those conditions begin either 
 as an inflammation of the gingival tissues, or that the presence of 
 gingivitis is an integral part of the process. If this be true, it may be 
 argued theoretically at least, that if the gingival tissues be kept in 
 health, the inception of deep peridental infections would be prevented. 
 And in actual practice this has proved to be true. Few observers 
 today believe that pyorrhea can occur in a mouth in which all the 
 gingivae are normal and in perfect health. Practically all agree, there- 
 fore, that the most successful method of preventing these conditions 
 lies in the prophylactic supervision of the gingival tissues. 
 
 In the foregoing consideration of the two most important and almost 
 sole avenues by which oral sepsis penetrates the natural barriers set up 
 against it, we have been led to see that the successful prevention of 
 the one lies in the prevention and control of dental caries, and of the 
 other in the prevention and cure of gingivitis. It may be said, therefore, 
 that if we could keep the teeth intact^ and the gingivae in health, 
 practically all danger of oral sepsis would be removed. In our discus- 
 sion of preventive dentistry, therefore, it is toward the control of these 
 two affections, dental caries and gingivitis, that the greatest attention 
 will be directed. 
 
 The Prevention of Dental Caries. — ^The history of the development 
 of our present knowledge of dental caries is an interesting one. Exami- 
 nations of crania of earlier races show that all through the centuries 
 every type of people has been afflicted with this dental affection. In 
 
PERIDENTAL AFFECTIONS 135 
 
 the early Greek and Roman writings frequent allusion is made to the 
 pain and discomfort of decayed teeth, and various speculations were 
 indulged in regarding the cause and nature of the process. It was in 
 the 18th century that the first real interest was showii in the study of 
 dental caries and through the years that followed various conflicting 
 opinions were held concerning the etiology of caries and about each 
 certain definite schools of thought and teaching were built until the 
 time of ]\Iiller who gave what seems to be the true solution of the 
 problem. 
 
 Prominent among these hypotheses, the inflammation theory received 
 a wide acceptance from 1754 to 1835 and was championed by such 
 men as Hunter, Fox, Bell, Jourdain and many others who believed that 
 the hard structures of the tooth possessed a blood circulatory system, 
 similar to bone, and that distiu-bances of circulation resulted in a 
 necrosis of the tooth quite like bone necrosis. They therefore looked 
 upon dental caries as a disease which originates in the interior of the 
 tooth, probably the dentin, and progresses outward to the surface of 
 the enamel, the process being alluded to by Koliker of Philadelphia 
 as a "bony abscess." 
 
 In 1835 Robertson of England took exception to the inflammation 
 theory and stated that it "is to chemical and not to inflammatory 
 action that the destruction of teeth must be attributed." He believed 
 that the acids of caries arose from the decomposition of retained food- 
 stuffs about the teeth. This view was corroborated by Tomes who, in 
 his histological studies of the teeth, found that the dentin contained 
 no bloodvessels and therefore could not undergo true inflammation. 
 He turned then to the chemical hypothesis of Robertson as also did 
 Magitot who in 1878 published the most comprehensive treatise of his 
 time in which he described dental caries as a disintegration of the tooth 
 by chemical substances either developed in the mouth or introduced 
 with the food. Watt in 1868 advanced the theory that free nitric, 
 sulphuric, and hydrochloric acids were generated in the mouth as a 
 result of disintegration of foods and that each acid produced a specific 
 tjTDe of dental caries. 
 
 In 1867 Bridgeman formulated a theory in which he considered dental 
 caries a destruction of the tooth by acids formed from electrolytic 
 action. He believed that the crown of the tooth and the giuns were of 
 different potential and that they with the saliva as an electrolyte 
 formed a battery in which acid substances were set free at the positive 
 pole (the c^o^^^l) which acids decalcified the enamel. So also S. B. 
 Palmer, in 1874, claimed that recurrent caries of a tooth beneath a 
 filling resulted from a difference in potential between the filling and the 
 dentin and in the presence of the saliva a current would be set up with 
 
136 PREVENTIVE DENTISTRY 
 
 the formation of acids which either decalcified the tooth or disintegrated 
 the fining. 
 
 It was in 1867 that Leber and Rottenstein first called attention to 
 bacteria as a causative factor in the carious process. They succeeded 
 in staining with iodin and identifying several varieties of mouth 
 organisms in carious dentin. They believed that an initial lesion of 
 the enamel by some other means was necessary for the bacterial propa- 
 gation in the dentin. At the World's Medical Congress in 1881 Miles 
 and Underwood in an exhaustive treatise on the subject characterized 
 dental caries as "a combined action of acids and germs." They 
 believed that the acids which were active in the process were produced 
 by bacterial organisms which lived upon the contents of the dentinal 
 tubuli. 
 
 At this time, the knowledge that bacteria caused disease was largely 
 theoretical as no one had been able to demonstrate conclusively the 
 pathogenicity of these organisms. It was not until Koch completed 
 his epoch-making studies in 1880 that specific bacteria could be shown 
 to cause definite lesions and diseases. This he accomplished by the. 
 formulation of four rules or tests by which the type of organism might 
 be determined and its responsibility as the cause of disease established. 
 The four rules of Koch are as follows: 
 
 1. The microorganism is present and discoverable in every case of 
 the disease. 
 
 2. It is to be cultivated in every case of the disease. 
 
 3. Inoculation from such culture must reproduce the disease in 
 susceptible animals. 
 
 4. It must be reobtained from such animals and again grown in pure 
 culture. 
 
 It so happened that W. D. Miller was closely associated with Koch 
 in his laboratory at the time he was pursuing his studies, and as soon as 
 the principle was definitely established, Miller immediately applied 
 Koch's four rules to the problem of dental caries, in order that he 
 might determine definitely whether or not the process was due to 
 bacterial action. It was diu-ing the following year that he gave 
 out the results of his studies in what is now known as the Mil- 
 lerian theory of dental caries. Briefiy, it may be stated as follows: 
 dental caries is primarily a decalcification of the enamel and 
 dentin of the tooth by organic acids which ha^e resulted from the 
 fermentation of carbohydrates in the mouth and is usually asso- 
 ciated with, and localized by, mucoid plaques or films. Sec- 
 ondarily the decalcified dentin is disintegrated by a proteolytic 
 process. The bacteria which produce the initial lesion of enamel 
 caries are not a specific variety but a relatively large group of 
 
PERIDENTAL AFFECTIONS 137 
 
 organisms which have the abihty to form acids when acting on 
 carbohydrates. The process of dental caries is therefore infective 
 in type but certain other attending conditions are necessary for the 
 bacterial action to be effective; namely, carbohydrate food material, 
 and a protective covering by which the acids formed may be held 
 against the tooth and protected from dilution and neutralization by 
 the salivary secretions. Under this so-called mucoid plaque the 
 process of acid production and enamel dissolution may go on unmolested 
 with the result that a lesion in the tooth is accomplished. After the 
 initial cavity is once formed, the bacteria advance deeper and deeper 
 into the tooth progressively decalcifying the enamel and the dentin 
 as long as they are undisturbed. The theory which Miller thus 
 formulated has remained until today as the only tenable concept of the 
 caries process which has so far been advanced. 
 
 Although the Millerian theory has given us a fairly definite picture 
 of the manner in which dental caries operates, it did not reveal the 
 methods by which the process may be prevented. Miller later turned 
 his attention to this phase of the-^subject and spent considerable time 
 in the study of caries prevention. He first sought for some form of 
 antiseptic by which he might eliminate mouth infection. He found it 
 impracticable and virtually impossible to continuously rid the mouth 
 of acid-producing organisms, so that he was convinced that means of 
 caries prevention did not lie in the use of antiseptics or bactericides. 
 Then he began investigation of the methods of mechanically cleansing 
 the mouth and of reducing the amount of carbohydrate and infective 
 materials about the teeth by means of the tooth brush and dentifrices. 
 This line of attack he was still pursuing at the time of his death. 
 
 Extension for Prevention.^ — Since the time of Miller, many valuable 
 additions have been made to our knowledge of the subject, but among 
 these there are few concrete suggestions as to the practical control 
 of the process. Of these the earliest method and undoubtedly the 
 most practical one, so far advanced, is the excavation of cavities which 
 have already begun in the teeth and the filling of the defects with a 
 substance which will arrest the process and preclude a subsequent 
 infection. This procedure has received its most rational and successful 
 application when carried out according to the principles outlined by 
 G. V. Black, known as "Extension for Prevention."^ Many have 
 observed that caries has a tendency to occur on certain definite areas of 
 the tooth such as the approximate surfaces, and in the sulci of the 
 occlusal surfaces, while it seldom occurs on the angles of the teeth or 
 the cusps. It is argued that if, in the preparation of a cavity, the walls 
 
 1 Black, G. v.: The Management of Enamel Margins, Dental Cosmos, 1891, p. 85. 
 
138 PREVENTIVE DENTISTRY 
 
 might be carried outside of the susceptible areas to those of relative 
 immunity, the liability of recurrence of caries would be greatly lessened. 
 The rationale of this method has been supported by years of clinical 
 evidence that leaves little room to doubt its efficacy in caries limitation. 
 It is true that many advocates of this principle have been overzealous 
 in its application, carrying the extension of cavities to great extremes 
 and needlessly sacrificing tooth structure; but those who have extended 
 cavities advisedly and with due consideration of other factors involved, 
 have been rewarded with a high degree of success. It follows therefore 
 that the early detection of caries defects in teeth and the successful 
 repair of these lesions in accordance with the present approved methods 
 of operative dentistry constitute the most effective means of controlling 
 caries when once the process has been inaugurated. The application 
 of these principles in operative dentistry is fully considered in a 
 succeeding chapter. 
 
 The Oral Hygiene Movement. — About ten years ago examinations of 
 children in public schools clearly revealed that a great majority of the 
 children were suffering from dental defects and severe oral sepsis for . 
 which they were receiving little or no remedial care. So apparent was 
 the need of dental services that municipal dental dispensaries were 
 instituted in the schools for the gratuitous care of the children. The 
 work accomplished was mainly that of cleansing the mouths and 
 teaching the children to keep them clean. On the assumption that 
 dental caries is a filth disease, it was hoped in this manner to limit to a 
 degree the occurrence of caries, and to reduce the oral sepsis present. 
 In addition to cleansing the teeth, inspection was made at regular 
 intervals and cavities were filled promptly in order that a minimum 
 amount of damage might be done by the carious process. The results 
 which have been attained have been so gratifying that school clinics 
 have come into almost universal adoption and have proved to be of 
 real economic value. 
 
 A further extension of this service has been more recently made in 
 the establishment of similar dental clinics for the benefit of workers 
 in various mercantile plants and factories. Regular dental examina- 
 tions of the employes are made and advice given them regarding the 
 care of their mouths. The only operations performed are 'brief pro- 
 phylactic treatments, extractions, and emergency relief of pain, the 
 patients being referred to the family dentist for permanent restorations 
 and fillings. Over sixty dental clinics of this kind are now in operation 
 in this country. Without exception they have proved to be of great 
 benefit to the employes of the institutions in which they are operating, 
 and have produced a marked increase in the efficiency of the whole 
 organization. 
 
PERIDENTAL AFFECTIONS 139 
 
 Oral Prophylaxis. — A most exacting regimen of oral hygiene has been 
 advocated and practiced by certain members of the profession. Acting 
 upon the hypothesis that "a clean tooth never decays," they spend 
 considerable time in polishing the several surfaces of each of the teeth 
 in the mouth in order that they may be easily cleansed by the patient. 
 They enlist the cooperation of their patients and instruct them in the 
 performance of a vigorous and thorough daily care of the mouth. 
 Such patients are seen regularly once a month for the purpose of cleans- 
 ing those teeth which were habitually missed and encouraging the 
 patients to perfect the personal care of their mouths. This method of 
 practice, which is known as oral prophylaxis, has been followed more 
 or less extensively by a large number of dental practitioners. Perhaps 
 the periodontists have attained the highest degree of efficiency in oral 
 prophylaxis, while other general practitioners have adopted the 
 principles wdth varying degrees of thoroughness. There is also a 
 difference of opinion as to whether prophylaxis actually prevents dental 
 caries. Certain practitioners affirm that they are able to eliminate 
 practically all caries from the mouths of patients so treated. In 
 evidence they submit many cases of individuals who have been sus- 
 ceptible to dental caries, who cease to have cavities occur under the 
 regimen of oral prophylaxis, and cases of women who have been carried 
 through the susceptible period of pregnancy without dental defect. 
 Many other practitioners having rigorously carried out this method of 
 strict oral prophylaxis, or a modification of it, state that they have been 
 able to stop the inception of caries in a large number of patients who 
 previously had been susceptible to a marked degree. The more con- 
 servative, however, do not as yet believe that immunity from dental 
 caries can, in all cases, be obtained in this manner, but that in a large 
 majority its rate of occm"rence is decreased and occasionally it may be 
 entirely prevented by the thorough and continuous practice of oral 
 prophylaxis. Those who have carried out this method with a less 
 degree of thoroughness, have found little or no benefit resulting from it 
 other than the general decrease of oral sepsis. 
 
 The diversity of opinion regarding the value of oral hygiene and 
 prophylaxis as a caries preventive, has led to considerable uncertainty 
 in the minds of many as to the rationale of its adoption. The familiar 
 picture of apparently clean mouths being vigorously attacked by dental 
 caries, and filthy mouths that are wholly immune, is to many a direct 
 contradiction of the slogan "clean teeth do not decay." They are, 
 therefore, unwilling to subscribe to or put into practice the principles 
 of strict oral prophylaxis with the hope of preventing dental caries. 
 Rather do they look and hope for the discovery of some other control- 
 lable factor in the process of caries by which more definite and tangible 
 
140 PREVENTIVE DENTISTRY 
 
 results may be obtained. Let us, then, at this time consider what other 
 methods have so far been suggested by dental research for the solution 
 of this problem. 
 
 Sulphocyanate in the Saliva. — In 1900 Micheals of Paris reported 
 studies which he had made of the saliva and its relation to dental caries, 
 stating that the secretions of caries susceptibles differed from those of 
 caries immunes. Among other constituents he noted a difference in 
 the amount of sulphocyanates which he considered to be significant. 
 Acting on this suggestion, a large group of men in this and other 
 countries, began a systematic search of the salivas of carious and non- 
 carious mouths and a wide interest was shown in the investigation. 
 Many reported that a relationship did exist between the sulphocyanates 
 and dental caries, and suggested that potassium sulphocyanate be fed 
 to individuals who were susceptible to dental caries for the purpose 
 of establishing immunity to that disease. Perhaps no other form of 
 caries prevention has received the attention this received for a time; but 
 later investigations discredited the premises of the theory and resulted 
 in its abandonment by all save a few of its most ardent supporters. 
 
 Glycogen in the Saliva. — Michaels also stated that the saliva con- 
 tained glycogen as a variable constituent^ and that it was increased 
 in amount by excessive carbohydrate diets and by diabetes. Follow- 
 ing this line of thought. Kirk has written voluminously upon the effect 
 of excessive carbohydrate diets as productive of glycogen in the salivary 
 secretions which in turn, he believes, furnishes pabulum for lactic acid 
 fermentation and dental caries. As a caries preventive, he suggests 
 the limitation of carbohydrates in the diet. There is little doubt that 
 carbohydrates are active factors in dental caries for without their 
 presence in some form, lactic acid fermentation could not take place. 
 But the assertion that the most important source of carbohydrates in 
 oral fermentation and dental caries is to be found in the salivary 
 secretions is open to serious objections. In a former contribution,^ 
 we have reported analyses made of the total carbohydrate content of a 
 series of salivas, comparing the results obtained to the caries suscepti- 
 bility in each case. By the most exact methods we were able to demon- 
 strate only the most minute quantities of carbohydrate which, when 
 compared with the sugars and starches habitually retained in the 
 mouths, we deemed to be too insignificant to be given serious con- 
 sideration in the process of caries. Moreover, we were not able to 
 find any analogy between the slight glycogen variations of the samples 
 tested to the caries susceptibility of the individuals from whom they 
 were taken. 
 
 1 Bunting and Rickert: Dental Caries, Jour. Nat. Dent. Assn., No. 4, p. 16. 
 
PERIDENTAL AFFECTIONS 141 
 
 In a series of articles which he is now pubUshing, Herman Prinz^ 
 states that he has made exhaustive search in saHvas to determine the 
 presence of carbohydrates and glycogen and has been unable to find 
 them. He definitely denies the presence of sugars in the normal 
 saliva. 
 
 On the other hand, it is a matter of common observation that millers, 
 bakers, and confectioners are frequently attacked by rapid and exten- 
 sive dental caries. Unless their mouths be vigorously cared for, rich, 
 sticky carbohydrate pabulum is adherent to the teeth and fermentations 
 are high. These are the extreme cases of carbohydrate retention to 
 which many other caries susceptibles who ingest considerable quantities 
 of sugars and starches approximate to a less degree, especially if the 
 mouth hj'giene is poor. In all of these the quantity of food retained 
 in the mouth furnishes ample material for lactic acid fermentations and 
 greatly exceeds any possible sugar content which the saliva might 
 possess. These retained carbohydrates, therefore, seem to constitute 
 a direct and primary factor in the production of dental caries, for they 
 by their presence, may act as the determining cause of that process. 
 It follows that all the measures of diet selection and mouth hygiene 
 which tend to reduce the sugar pabulum habitually sticking about 
 the teeth will have a direct influence upon the inception and progress 
 of dental caries. 
 
 Diets. — Sim Wallace^ has written extensively on the subject of diets 
 and their relation to dental caries. He believes that the soft and pappy 
 foods which constitute the bulk of diets for younger children are 
 responsible for the prevalence of dental caries during the early years 
 of life. Such foods require little mastication and tend to form a sticky 
 carbohydrate pabulum about the teeth favorable to lactic acid fermen- 
 tation. Rather, he suggests that children be fed hard and tough foods 
 which afford the necessary exercise for proper development of the jaws, 
 stimulate a copious flow of saliva and salivary ferments to act upon 
 the food in the mouth, scour the teeth and cleanse them from food 
 debris. He also urges that the amount of easily fermentable carbo- 
 hydrates be limited and followed by fresh fruits, preferably apple, or 
 an acid food or drink which should always constitute the ending of 
 every meal. The results which he has obtained by practical applica- 
 tion of these principles in the diets of children in orphanages and in 
 boarding schools have convinced him of their efficacy and their super- 
 iority over any methods of artificial prophylaxis. In view of the data 
 which he presents he claims^ "that dental caries is one of the most 
 
 1 Dental Cosmos, February, 1918, et seq. 
 
 2 Prevention of Common Diseases of Childhood, 1912. 
 
 5 Wallace, Sim: Prevention of Dental Caries, Dental Record, 1912. 
 
142 PREVENTIVE DENTISTRY 
 
 easily and certainly preventable of diseases and there would seem now 
 no valid excuse for the bringing up of children with decayed teeth." 
 
 In his monumental contribution to the subject, H. P. PickerilP also 
 treats dental caries as a problem of dietetics. In many respects his 
 conception of the cause and control of dental caries is similar to that of 
 Wallace, but it differs in that he accentuates the importance of acid 
 foods and fruits in the diet over that of hard and tough substances. 
 Like Wallace, he believes that the occurrence of caries is dependent 
 upon the ability of the mouth to cleanse itself after meals, and that 
 caries may be prevented by the selection of a diet which will promote 
 the normal cleansing factors of the mouth. By extensive analyses of 
 the saliva, he shows a variation in that secretion in response to the 
 stimulation of foods. Dry bread increases the amount of saliva 2 to 1, 
 and apple or orange increases it 6 to 1 . He finds that all acid and highly 
 flavored foods increase the saliva in amount, in alkalinity, and in 
 ptyaline content, all three of which are, in his opinion, important in 
 the cleansing of the mouth and the prevention of dental caries. On the 
 other hand, bread and butter, meat, biscuits, sugars, tea, milk and" 
 other sapid foods are either neutral or depressant in salivary stimulation. 
 He suggests for caries control that all diets should begin and end with 
 some form of acid, preferably the organic or fruit acids; that sugars 
 should not be eaten to excess and should always be incorporated with 
 some form of acid ; and that, so far as possible, the diet should consist 
 of foods having a high flavor and acid taste. He also claims that alka- 
 line dentifrices have a depressant effect upon the secretions, tending 
 to mouth acidity, and suggests the use of acid mouth washes, prefer- 
 ably potassium acid tartrate, 0.50 per cent. The author reviews the 
 prevalence of dental caries among the various nations and peoples of 
 the world and states that among civilized races the susceptibility to 
 caries is high, while in many uncivilized tribes caries susceptibility is 
 low; that the diets of the civilized people are largely unnatural, sapid, 
 and low in acids, while those of the uncivilized people are composed of 
 natural foods, highly flavored and acid; and that caries susceptibility 
 is not due to civilization per se, but rather to the adoption of a civilized 
 diet. 
 
 The views of Pickerill have been concurred in by Wm. Gies of Colum- 
 bia University and his co-workers^ in their voluminous contributions 
 to this subject. They strongly object to the use of alkaline dentifrices 
 and urge the adoption of acid mouth washes as a means of caries pre- 
 vention. They suggest that organic acids be used for this purpose, 
 and prefer vinegar, either full strength or diluted claiming that it dis- 
 
 1 The Prevention of Dental Caries, H. P. Pickerill, 1912. 
 
 2 Jour. All. Dental Soc, 1912, p. 400; 1913, p. 283 et al. 
 
PERIDENTAL AFFECTIONS 143 
 
 organizes the mucoid plaques adherent to the teeth and stimulates a 
 copious flow of saliva, thereby decreasing oral fermentations and the 
 tendency to dental caries. 
 
 It is not practicable to discuss fully in this chapter the significance 
 of these views of caries prevention. It is evident, however, even from 
 a superficial examination that most authors consider the prompt 
 elimination of food debris from the mouth and the attainment of oral 
 cleanliness as matters of the highest importance in the control of dental 
 caries. The possibility of attaining this object by diet alone may be 
 determined -only by a wholesale application of these principles to a 
 large number of subjects under direct observation. That hard and 
 coarse foods mechanically cleanse the teeth and stimulate an active 
 flow of saliva to wash the food particles from the mouth is a well-known 
 fact. Consequently, they lessen the amount of carbohydrate material 
 about the teeth and reduce lactic acid fermentation. It is also true 
 that acids stimulate the salivary secretions in amount and in alkalinity 
 and have a tendency to leave the mouth clean. But the universal 
 adoption of acid diets and acid mouth washes is open to question. 
 In a former communication^ we have reported certain untoward effects 
 arising from the use of acid diets. Patients under our observation 
 gave evidence of pronounced gastric and digestive disturbances while 
 following a prescribed acid diet, and several developed a severe urticaria 
 which could be attributed only to hyperacidity. Others were found 
 who could not tolerate acid mouth washes as their teeth became 
 exceedingly sensitive to slight changes in temperature during their 
 adoption. Prinz also states^ as his opinion that the correctness of the 
 use of acid mouth washes is not substantiated by clinical experience, 
 that the pharmacologic principle involved in the selection of such solu- 
 tions is erroneously applied, that constant forcible stimulation of the 
 salivary glands by acids is followed by an impairment of glandular 
 function, and that the acidity of the solution kills the important salivary 
 ferments. It seems wise, therefore, to withhold opinion in regard to 
 this particular procedure until further scientific data have been 
 gathered. It is possible that in certain selected cases where the 
 saliva is thick and mucinous the judicious use of acids in the diet and 
 acid mouth washes may have a beneficial effect; but in cases of thin, 
 watery salivas with a tendency toward erosion of the teeth, it seems to 
 us that acids are contra-indicated. 
 
 Carl Rose looks upon dental caries as a form of physical decadence 
 and degeneration due to civiHzation. The uncivilized man, he believes,^ 
 
 1 Dental Review, 1916, p. 423. 
 
 2 The Therapeutic Efficiency of Oral Preparations, Jour. All. Dental Soc, June, 1916. 
 
 3 Dental Cosmos, 1912, p. 1214. 
 
144 PREVENTIVE DENTISTRY 
 
 has better teeth and less dental caries as a result of the laws of survival 
 of the fittest and sexual selection. Only those having good dental 
 organs are able to subsist on the hard and tough foods which compose 
 their diet. The primitive male chooses a mate that is strong physically 
 and has sound teeth, and the children which result from such union 
 inherit the strong physique and well developed dental organs of both 
 parents, thus continuing the race of caries immunes. Civilized man. 
 on the other hand, is so protected by law that physical strength is not 
 necessary to his existence and the character of his food does not require 
 that his teeth be sound or in a high state of efficiency. Natural selec- 
 tion or survival of the fittest, as regards physical development and 
 dental health has therefore been supplanted among civilized races by 
 panmixia and survival of the physically unfit resulting in a general 
 physical deterioration, one phase of which is dental defect and a ten- 
 dency to dental caries. Rose, accordingly, looks upon the prevalence 
 of dental caries among civilized peoples as a problem in eugenics and 
 believes that the remedy may be found only in the intermarriage of 
 those who are strong in body and perfect as to dental apparatus. He 
 naively accuses the dental profession of aiding in the process of evolu- 
 tionary decadence of the teeth by so repairing and replacing decayed 
 teeth with crowns and bridges that it is difficult for the casual observer 
 to determine who has good teeth and who has not. The views of the 
 author thus expressed are interesting and worthy of consideration; 
 but the means of control of dental caries which he suggests, namely, 
 the regulation of intermarriage, involves weighty problems in social 
 economics which as yet are unsolved, and their application on a large 
 scale at the present time is impracticable. 
 
 Rose also reports^ that in an examination of a large number of school 
 children in Germany, it was very evident that those who came from 
 sections of the country in which the calcium salts of the water and 
 soils were high had better formed teeth and better dental health than 
 did those who came from localities in which the calcium salts were low. 
 He states that the enamel of the hard and resistant varieties of teeth 
 has a better organization and contains a higher percentage of calcium 
 salts than does that of the softer forms. It is this degree of organization 
 and. calcium salt content that, in his opinion, renders them immune to 
 dental caries. In view of this, he suggests that a high calcium diet be 
 maintained and that the calcium be taken in the form of natural mineral 
 waters containing calcium. 
 
 The latter views of Rose coincide with those of PickerilP who demon- 
 strated that the enamels of soft and more poorly formed teeth were 
 
 1 Monatschrift f. Zahnheilkunde (abstract in Dental Cosmos, 1909, p. 135). 
 
 2 Loc. cit. 
 
PERIDENTAL AFFECTIONS 145 
 
 porous and contained canals which ran from the surfaces of the enamel 
 to the interior. Enamels of hard teeth he found to be compact and 
 free from canals. Also, that the enamels of all teeth are porous at the 
 time of their eruption, and that in time the enamel surface undergoes 
 a process of condensation. In some mouths the enamel becomes hard, 
 dense and sclerotic, the hard tooth, and in others the process is less 
 complete, the tooth enamel is soft and is more or less porous. Pickerill 
 states as his opinion, for which he has no definite proof, that the 
 condensation of the enamel after eruption is produced by infiltration 
 of calciimi salts from the saliva, and that the degree of condensation 
 is dependent upon the degree of calcium salt concentration in the saliva. 
 
 In former contributions^ we have given the results of determinations 
 made of the calcium in a large number of salivas. We found that the 
 saliva of every individual contained a definite percentage of calcium 
 which remained fairly constant in amount from day to day. Also, 
 that in those mouths in which the teeth are well formed, sound, and 
 free from dental caries, the calcium content of the saliva is uniformly 
 high; while in those cases in which the teeth are soft and carious, the 
 percentage of calcium in the saliva is low. So definite and in^"a^iable 
 were the findings which we obtained at that time and which are con- 
 stantly being corroborated by cases selected from the college clinic, 
 that we present them as definite proofs of the view that the quality of 
 the enamel and tendency of the teeth to caries are dependent upon the 
 calcium salt content of the salivas which bathe them. Of all the other 
 salivary constituents and factors which have been suggested as caries 
 controllers, we have found none which bear so close and definite a 
 relationship to clinical conditions. 
 
 We have fiu'ther sho^A^l- that the tooth is not an impermeable sub- 
 stance, but that salts and fluids may readily pass from the exterior of 
 the enamel through its substance to the dentin and pulp; and, con- 
 versely, from the pulp through the dentin and enamel according to the 
 laws of osmotic pressure. This being true, the tooth can no longer be 
 viewed as a stable, unchangeable substance, but rather as one that is 
 capable of being built up and condensed by salts from the blood and 
 saliva through osmotic interchange of these fluids through the tooth. 
 It is obvious, therefore, that in accordance with the laws of osmotic 
 pressure through permeable membranes, the degree of such condensa- 
 tion will be in direct relationship to the salt concentrations in the blood 
 and the saliva. 
 
 In om- attempt to make practical application of these theories for 
 the prevention of dental caries, we were met with certain difficulties. 
 
 1 Bunting and Rickert: Jour. Nat. Dent. Assn., 1912, p. 287; 1917, p. 81. 
 
 2 The Tooth, a Permeable Membrane, Jour. Nat. Dent. Assn., 1918, p. 519. 
 10 
 
146 PREVENTIVE DENTISTRY 
 
 Experimental medicine has for a long time sought means by which it 
 might permanently increase the calcium salt content of the blood, but 
 as yet no satisfactory method has been found. We, therefore, in our 
 endeavor to raise the calcium salts of the saliva by forced calcium 
 feeding and stomachic medication were confronted with the same diffi- 
 culties. At some future time, when the process of calcium metabolism 
 shall be more clearly understood and methods found by which it may 
 be raised, we may be able to increase permanently the calcium salt 
 content in salivas which are low in that constituent to the betterment 
 of the teeth and the reduction of dental caries. At present we are 
 limited to two methods of procedure in such cases, namely, the selection 
 of diet to the full calcium requirements for metabolism, and the use of 
 mouth washes containing calcium. These methods we have employed 
 on selected cases for some time with seemingly beneficial results, but 
 sufficient time has not yet elapsed to present proofs of their efficacy 
 further than the reasonableness of their adoption. 
 
 Viewing thus briefly the various methods of caries control we may 
 ask which of these methods are worthy of adoption to meet present- 
 day needs and in what manner they may be applied by the general 
 practitioner. It is evident that in dealing with caries susceptibility, 
 two distinct classes of causative factors present themselves, either of 
 which may act singly or in conjunction with the other: First, those 
 general and constitutional disorders which favor the carious process. 
 For example: cases of nutritional disturbance resulting in poor tooth 
 formation and deficient calcium in the salivary secretions; cases of 
 increased susceptibility as the result of general disease, bodily weakness, 
 nervous disorders or pregnancy; and those cases in which caries has 
 become acute following a change in habitat or climatic conditions. The 
 second class of factors includes those which are local and oral, namely, 
 the retention of food in certain localities of the mouth by irregularity 
 of the teeth, overhanging fillings, etc.; a general excessive accumulation 
 of carbohydrates in the mouths of children, millers, candy makers, and 
 those having habitually unclean mouths; and finally, the presence in 
 the mouth of virulent acid-forming organisms. It will be seen that 
 these two classes of causative factors may occur in an almost endless 
 number of combinations, making the analysis of every case an extremely 
 complicated matter. Also, that in those cases in which the first, or 
 constitutional group of factors predominates, we have at the present 
 time little means of control. But in those cases in which the second, or 
 local factors are the determining ones, definite and tangible methods 
 are at hand by which we may reduce the virulence of attack or entirely 
 prevent it. These methods are all those which make for continuous 
 mouth cleanliness and oral hygiene. 
 
PERIDENTAL AFFECTIONS 147 
 
 The field of oral hygiene is a broad one. In its practical application 
 the greatest benefits as regards caries control are to be obtained during 
 the age of childhood. As the deciduous teeth, one by one are lost and 
 are replaced by their permanent successors, the food has a tendency to 
 become packed and retained about the teeth due to the irregularities 
 of the dental arch, oral fermentations are high, and dental caries com- 
 mon. The enamels of newly erupted teeth, not having been condensed 
 by contact with the saliva, are imperfect and at this time are least 
 resistant to the inception of caries. Cavities, when once begun, grow 
 rapidly and early involve the pulp, resulting in its death and many 
 times in severe periapical infection. It is during this particularly 
 susceptible period of childhood that effective measures of caries control 
 are most necessary; for could we conserve the teeth of children and 
 bring them to manhood and womanhood with perfect dentures, we 
 would greatly enhance their chances for maintaining dental health 
 throughout the remainder of their lives. To this end there are certain 
 definite and obviously effective methods of procedure by which the 
 teeth of children may be preserved. These methods are of assured 
 value and quite apart from any theories or speculations regarding caries 
 control. Although these measures are well known to the dental 
 profession, it is regrettable that a great many practitioners fail to put 
 them into effect because of the fact that they are reluctant to operate 
 on children. They prefer to wait until their little patients are older, 
 then to build bridges and to make large restorations to repair as best 
 they can the damage that has been done. This is not a pleasant or 
 comforting admission, but, unfortunately, it is true. 
 
 A rational method of oral hygiene for children might be outlined 
 somewhat as follows: children should be seen regularly by the 
 family dentist for the purpose of assisting and encouraging them to 
 keep their mouths clean; cavities should be discovered early and filled 
 in their incipiency; imperfect sulci on bicuspids and molars should be 
 protected ; orthodontic interference should be given whenever indicated 
 to promote normal development of the dental arch; children should be 
 encouraged to include in their diet hard foods and a limited amount of 
 sweets combined with tart and acid fruits; special emphasis should be 
 given to the foods which are high in calcium, as milk, butter-milk, and 
 cheese, celery, spinach, turnips, radishes, string beans and kidney beans, 
 cabbage, cauliflower, and chard, in order that calcimn metabolism 
 may be amply provided; and, finally, the frequent use of lime water 
 as a mouth wash should be urged. A one-half of a saturated solution 
 of lime water seems to be beneficial as it increases the intra-oral calcium 
 content, softens the plaques about the teeth, and neutralizes acids 
 which may be present. 
 
148 PREVENTIVE DENTISTRY 
 
 This, or a similarly efficient regimen of mouth hygiene, for children 
 is being carried out most completely by certain dentists who have 
 limited their practice to the treatment of children. In this manner 
 they are bringing their patients through the susceptible age of child- 
 hood to maturity with a complete and often perfect dental apparatus. 
 The number of children so treated is comparatively small, but it is an 
 ever-increasing one. The great majority, however, must be cared for by 
 the general practitioner and the community dental clinic. For these the 
 task is colossal and may be accomplished only by the hearty cooperation 
 of every practitioner in the attempt to do his part in caring for the 
 children under his supervision. Could this work be performed com- 
 pletely, there would result a generation of people who would require 
 far less dental attention than the present one and for whom the problem 
 of dental infection and its attendant systemic involvement would be 
 largely solved. 
 
 Passing from the age of childhood to that of maturity, we find a 
 somewhat different set of conditions presented in regard to caries 
 control. Usually all the teeth have erupted and their enamels have 
 become more or less condensed. They have become established in a 
 certain fixed and permanent state of caries susceptibility, or immunity, 
 as the case may be, dependent upon the balance of forces which exist 
 in the oral environment. It is true that individual cases may change 
 from time to time in their susceptibility to dental caries as the result 
 of changes in general health or life conditions, but it is well known that 
 the majority may be classified as belonging to certain definite types of 
 virulence. For the relief of those cases which have a tendency toward 
 dental caries, we are limited for the present to those measures which 
 will most effectually eliminate or reduce the carbohydrates and fer- 
 mentations which are essential to the carious process. Could we but 
 keep the teeth continuously free from these, dental caries could not 
 exist. But mouth cleanliness is at best but a relative matter for lactic- 
 acid fermentations undoubtedly do exist in all mouths to a greater or 
 less degree. Our only hope, therefore, in oral prophylaxis is to reduce 
 these fermentations to the point where the other protective forces of 
 the mouth will establish caries immunity. It must be admitted that 
 the complete elimination of caries in every case by oral prophylaxis is 
 impossible; for, in certain mouths the forces of caries susceptibility 
 are very strong and the protective powers correspondingly weak. 
 Fortunately, it is also true that a very large percentage of susceptible 
 cases may be made practically immune and the severe types reduced 
 in virulence by the rational application of prophylactic measures. 
 After viewing the work of many operators who are practicing preventive 
 dentistry most intensively, the author personally applied the principles 
 
PREVENTION OF PYORRHEA ALV SOLARIS 149 
 
 of prophylaxis to a group of patients to substantiate or disprove the 
 claims which were made as to the efficacy of such measures. These 
 patients had been mider personal observation for some time and many 
 of them had been strongly susceptible to dental caries for years. In 
 several cases so treated, dental caries has not occurred during the past 
 four years, although previous to that time cavities appeared \\'ith 
 frequent regularity. Others showed a marked decrease, having but 
 two or three cavities diuing that time. One particularly suscept- 
 ible case was immune for three years and then suddenly became 
 susceptible coincident ^^'ith a protracted illness and general debility. 
 The results obtained from this limited number of cases have clearly 
 demonstrated that a regimen of strict oral prophylaxis does limit, and 
 in many cases^ controls the occurrence of dental caries. 
 
 THE PREVENTION OF PYORRHEA ALVEOLARIS. 
 
 In a succeeding chapter which -^tII be devoted to that subject, the 
 history of our present knowledge of the disease commonly knoT\Ti as 
 pyorrhea alveolaris and the various causative factors wliich are con- 
 nected \\dth the process "^ill be set forth in detail. By a careful perusal 
 of the matter there presented it "^-ill be seen that the author, after 
 having reviewed all the important theories and speculations thereto, 
 concludes that pyorrhea is a distinctly infectious process acting in 
 conjunction -^-ith a lowering of local tissue resistance. That is, the 
 process consists in a progressive destruction of the tissues about the 
 teeth by infectious organisms resulting in the formation of characteristic 
 pyorrhetic pockets. But these infectious organisms do not produce 
 their characteristic results upon the tissues unless the natural resist- 
 ance of these tissues against infections has been destroyed by some 
 form of injury or disturbance of circulation and metabolism. It 
 follows, that although the disease is essentially an active infective 
 process the determining factor in every case consists in one or more 
 predisposing causes which lower the resistance of the local tissues and 
 make the infective invasion possible. Fiu-ther, it may logically be 
 inferred that if the peridental tissues could be protected from injury 
 and kept in health and normal resistance, pyorrhea would most 
 effectually be prevented. At the present time of all the methods which 
 have been suggested for the prevention of peridental diseases those 
 measures which have been directed toward the maintenance of health 
 and normal resistance m the gums and gingi^'al tissues ha^'e yielded 
 the most beneficial results. 
 
 It has been pointed out previously that the mucous membrane 
 of the oral cavity normally possesses a high degree of resistance 
 
150 PREVENTIVE DENTISTRY 
 
 against infections. But, when the gingival tissues are disturbed either 
 by local irritations or by systemic fault of metabolism, gingivitis is set 
 up, the gingival tissues lose their normal tone and fall away from the 
 necks of the teeth. In this manner the gingival crevice is opened and 
 an opportunity is offered for the entrance and growth of oral micro- 
 organisms, which process constitutes the first step in the great majority 
 of cases of incipient pyorrhea. In general, the local causes of gingivitis 
 consist of various traumatic injuries, as the impaction of food, encroach- 
 ment of calculus, overhanging fillings, crowns and bridges, and exces- 
 sive stresses upon the teeth due to malocclusions; chemical injuries as 
 persistent localized growths of bacteria about the necks of the teeth 
 which continually irritate the gingival tissues; and certain other special 
 local irritants. The general or constitutional causes of gingivitis 
 consist of circulatory poisons such as lead, mercury, etc., or of general 
 disturbances of circulation and nutrition by which the metabolism of 
 the local tissues is altered. Of these two types of injury the local 
 causes are in the majority. Indeed, it may be seen in clinical practice 
 that when all local irritations are removed and the circulation of the " 
 peridental tissues is stimulated by proper massage, the gingival tissues, 
 as a rule, may be restored to health and maintained in that state even 
 in the presence of evident general and systemic disturbances. 
 
 The practice of preventive dentistry as regards the control of peri- 
 dental disease, therefore should consist of the thorough prophylactic 
 removal of all local irritants and other injurious influences from the 
 teeth and the peridental tissues. This should be accompanied by the 
 correction, so far as possible, of all systemic faults and the stimulation 
 of the circulation in the peridental tissues. By a rational application 
 of these measures it will be discovered that gingivitis is the most easily 
 and certainly preventable of all dental diseases. And it also follows 
 that in preventing gingival disturbance and by maintaining the health 
 and normal resistive powers of these tissues, the great majority, if not 
 all of the more serious peridental diseases are effectually prevented. 
 
 In all of the foregoing it will be seen that as we survey the whole field 
 of preventive dentistry, and the methods of procedure which thus far 
 have been suggested for the control of the two most important diseases, 
 namely, dental caries and pyorrhea alveolaris, oral prophylaxis in its 
 broadest application offers the greatest hope of success. Not that 
 these measures are presented as an infallible panacea for dental ills, 
 but that the faithful performance of those local procedures which 
 make for oral and dental health constitutes the most reasonable and 
 practical method of at least partial prevention with which we at this 
 time may combat dental disease. The efficacy of this form of practice 
 has been demonstrated clearly by a large group of operators who have 
 
ORAL PROPHYLAXIS 151 
 
 intensively applied the principles of oral prophylaxis to a large number 
 of patients with the result that for them dental and oral diseases have 
 been largely eliminated. These same procedures as outlined in the 
 following section may well be adopted in a modified form by every 
 dental practitioner. 
 
 ORAL PROPHYLAXIS. 
 
 The term prophylaxis has been widely applied in dentistry to the 
 operation of cleaning the teeth; so much so that in the minds of many 
 it has come to be synonymous with that procedure. In its broadest 
 sense, however, oral prophylaxis consists of not only cleaning, the 
 teeth, but also includes all measures which tend to protect the mouth 
 tissues from disease, and make for dental and oral health. Oral 
 prophylaxis therefore embraces all methods by which the various 
 harmful influences may be removed from the dental and peridental 
 tissues, and the tissues left in such condition that a continual mainte- 
 nance of oral cleanliness and oral health is possible. 
 
 In general, the practice of oral prophylaxis in a broad sense consists 
 of the following procedures: 
 
 1. Removal of all calcareous deposits, stains and other extraneous 
 substances from the teeth. 
 
 2. Smoothing and polishing of all exposed tooth surfaces and rough 
 fillings. 
 
 3. Detection and filling of all cavities. 
 
 4. Restoration of faulty proximate contacts and tooth contours. 
 
 5. Removal of overhanging portions of fillings, crowns, bridges, etc. 
 
 6. Relief of undue stresses on the teeth. 
 
 7. Protection or filling of defective sulci. 
 
 8. Instruction of the patient as to daily personal care. 
 
 9. Sustained periodic supervision and assistance. 
 
 It will be seen that all of the above procedures are directed toward 
 the removal of irritating and harmful influences from the teeth and 
 surrounding tissues and the establishment of oral conditions in which 
 the mouth will be practically self-cleansing, or capable of being 
 cleansed by the personal efforts of the patient. The question has 
 often been raised as to the need of such prophylactic measures and 
 the possibility that in their performance actual harm may be done. 
 Objection has been made to polishing the tooth surfaces on the ground 
 that the enamel would thereby be thinned and weakened and that 
 this operation could not be accomplished without doing irreparable 
 damage to the peridental tissues. It is undoubtedly true that as the 
 result of many overzealous and radical exponents of this form of 
 practice, an excessive amount of enamel substance has been removed 
 
152 PREVENTIVE DENTISTRY 
 
 from the teeth and extensive injury to the peridental tissues produced. 
 But these distressing and unwarranted procedures which have been 
 done in the name of oral prophylaxis cannot be construed as a real 
 objection to that process when safely and sanely performed. Upon 
 careful examination it will be seen that in a large percentage of mouths 
 the teeth are more or less incrusted with salivary calculi which act as 
 irritants to the peridental tissues and by virtue of the rough surfaces 
 which they present tend to mechanically hold food in contact with the 
 teeth and gums. On those tooth sm-faces which are not so incrusted 
 it will be seen that the enamel is frequently dull and rough, lacking 
 the -natural luster which it normally should possess. Tooth surfaces 
 of both classes offer considerable retention for food and bacterial 
 plaques; and cannot be cleansed by natural forces or the personal 
 efforts of the patient. The great prevalence of the roughened enamel 
 surfaces to be found in the mouths of the great majority of people 
 is evidently due in part to the soft and pappy diets which are almost 
 universally adopted today by the civilized world. In the primitive 
 and uncivilized races we find teeth with highly polished enamel surfaces 
 and a marked freedom from dental disease. Among these people the 
 diet contains more gritty and hard foods which in the act of mastication 
 produce considerable mechanical cleansing and polishing of the enamel 
 surfaces. Moreover, many races that are noted for the brilliance and 
 lustre of their teeth are known to spend considerable time each day 
 rubbing the surfaces of their teeth with various roots and herbs which 
 cleanse and polish them. It follows therefore that those who live upon 
 foods that tend to stick to the teeth rather than scour and cleanse 
 them, must substitute some artificial mechanical measures for the 
 natural action of the food if they would have clean and healthy mouths. 
 As a rule, the indifferent and irregular habits of personal dental care 
 on the part of the patient are not sufficient to compensate for the lack 
 of friction which the hard and gritty foods would give. Consequently, 
 in the great majority of mouths concretions form on those portions of 
 the teeth which receive the least friction and the enamel surfaces which 
 are continuously covered by bacterial films and plaques become 
 etched and roughened by acids which are formed on the spot. For 
 these it is evident that the first step in oral prophylaxis should be the 
 removal of concretions and the subsequent polishing of all tooth surfaces 
 to the end that the patient may cleanse the teeth properly by his 
 personal efforts. It is true that in some mouths the teeth are naturally 
 polished and clean. In such cases it will be found that the salivary 
 secretions are thin and low in mucin, while the teeth are frequently 
 abraded giving evidence of heavy and thorough mastication. From 
 this we see that in them the tendency for lodgement of food and calculi 
 
ORAL PROPHYLAXIS 
 
 153 
 
 upon the teeth is sHght and the natural friction of mastication is marked. 
 As a result, the mouth is naturally self-cleansing and as a rule free from 
 disease. This t}^e is, however, in the great minority while the rough- 
 ened and incrusted denture is much more common. 
 
 It follows, therefore, that the great majority of our patients need 
 assistance in the care of their mouths. They need careful and thorough 
 operative procedures to remove all forms of irritation from the dental 
 and peridental tissues, and to eliminate all mechanical hindrances to 
 oral cleanliness. Unless this be done, oral cleanliness is impossible in 
 the mouth of the average patient. 
 
 1. Removal of Concretions from the Teeth. — Calcareous deposits 
 on the exposed sm'faces of the teeth form masses which are more or 
 less evident and may be recognized easily (Fig. 88) . For their removal 
 
 ■j^H 
 
 ^mmmuMjg^imH^^m^gm^ ^- 
 
 ■ ' 1 ^ 
 
 
 • W^ ^w 
 
 ! 
 
 *" 
 
 ■M^' ^ 
 
 Fig. 88. — Salivary calculi. 
 
 a large variety of instruments have been suggested, scalers, cleaners, 
 files, planes, chisels, etc., among which considerable latitude for the 
 personal preference of the operator may be exercised. The chief 
 requisite of each is that by their use the deposits may be effectually and 
 completely removed and that the enamel siu-face will not be scratched 
 or injured in the operation. Calculi which are formed on the roots of 
 the teeth beneath the free margin of the gum are much more difficult 
 to remove. As a rule, they are entirely covered by the gum tissues, 
 are hidden from view, and may be detected only by an instrumental 
 exploration of the subgingival crevice. Certain forms are fine and 
 granular while others consist of thin and plate-like scales firmly 
 adherent to the surfaces of the root (Fig. 89) both of which may be 
 overlooked and are difficult of removal when discovered. 
 
154 
 
 PREVENTIVE DENTISTRY 
 
 In the removal of dental calculi, especially the subgingival varieties, 
 too much stress cannot be placed upon the means of discovering and 
 locating these deposits. Since they are frequently hidden from view, 
 the mouth mirror as a means of diagnosis cannot be relied upon. 
 Therefore, the operator must cultivate a keen sense of touch by which 
 he may read the character of the enamel and cementum surfaces by 
 passing the point of an explorer or other instrument over them. In 
 this manner he may judge as to the roughness or smoothness of these 
 surfaces and may detect all deposits and concretions which may be 
 attached to them. To this end it is desirable that the operator culti- 
 vate the habit of grasping and using the instrument after the manner 
 
 Fig. 89. — Subginlval calculi. 
 
 of holding the pen in the old Spencerian style of writing (Figs 90 
 and 91). 
 
 If the instrument be held lightly with the muscles of the hand at 
 ease and uncramped, the vibrations which are set up as the point is 
 passed over various rough and smooth surfaces will be transmitted to 
 the hand and will accurately portray the character of these surfaces. 
 For instance, one may try the experiment of passing an instrument 
 held in this manner over the surfaces of etched and smooth glass and 
 may easily distinguish one from the other by the feel or vibrations of the 
 instrument. If, on the contrary, the instrument be held tightly and 
 considerable force continually exerted upon it, the muscles of the hand 
 soon become cramped and the keen sense of touch is lost, 
 
DUAL PROPHYLAXIS 
 
 155 
 
 It is equall}' important tluit in all forms of prophylactic instrumenta- 
 tion the same Spencerian type of hand grasp should be maintained and 
 
 Fig. 90. — Method of lidldinji instrument. 
 
 the fingers should remain as nearly passive as is possible. If they are 
 continually flexed and extended for the purpose of moving the instru- 
 
 FiG. 91. — Method of holding instrument. 
 
 ment over the surface of the tooth, the sense of relationship is lost, and 
 as a result of continued muscular effort the fingers become cramped 
 
156 
 
 PREVENTIVE DENTISTRY 
 
 and the tactile sense is dulled. Rather should the instrument be 
 actuated by a rocking motion of the whole hand describing the arc 
 of a circle about the tip of the second or third finger which rests upon 
 some fixed point in the mouth as shown in Fig. 91 . This is accomplished 
 by flexion of the wrist or elbow by which the instrument may be made 
 to traverse the surface of the tooth in any desired direction without 
 any effort of the fingers other than to lightly hold the instrument in 
 position. If this method be adopted the operator may feel the sur- 
 faces of the tooth above and below the gum margins searching for 
 extraneous deposits and when he has found them he may, by the 
 momentary exertion of pressure, pry off the foreign body and continue 
 to smooth the tooth surfaces until by the sense of touch through the 
 instrument he knows that the deposit is entirely removed. In this 
 manner he may operate for hours still maintaining his keen sense of 
 touch and the free use of his hand. 
 
 Z 3 4 
 
 Fig. 92. — Tompkins' scalers. 
 
 In the selection of instruments adapted to the practice of oral prophy- 
 laxis the average practitioner may be easily confused by the wide range 
 of types which are offered by the dental supply houses and private 
 individuals. Leaving out of account the many clumsy and crude forms 
 which have no place in preventive dentistry, there are in common use 
 today four basic types of prophylactic instruments, namely, Tompkins' 
 scalers and Younger' s scalers, files, and planes. 
 
 The Tompkins' scalers (Fig. 92) consist of variously shaped instru- 
 ments, having aright angle turn at their extreme end. They are intended 
 to be used with a pull motion by which they may be hooked over a 
 calcareous deposit and remove it. This type of instrument has been 
 widely accepted and has been adopted in a modified form in the 
 Buckley, Logan and Adair sets. The chief objections to them are that 
 they are not adapted to smoothing the enamel or cementum after the 
 removal of the calculi, and in the hands of the inexperienced operator 
 
ORAL PROPHYLAXIS 
 
 157 
 
 considerable damage may be done to the tooth surfaces by the sharp 
 corners of the blade. 
 
 The Younger type of scalers (Fig. 93) is made in the form of slender 
 elongated spoons, the shanks of which are bent at various angles to 
 reach the several surfaces of the teeth. These are also intended to be 
 used with a pull motion, the instrument being so tipped that the 
 
 ^^=^/==^ 
 
 3 4- 5 6 
 
 Fig. 93. — Younger's scalers. 
 
 lateral edge of the blade is presented to the surfaces of the tooth at an 
 acute angle. In this manner the blade may be slipped down beneath 
 the gum margin at a right angle to the long axis of the tooth and by a 
 drawing motion the surfaces of the tooth may be cleansed and smoothed 
 without injury to the soft tissues (Fig. 94) . This type of instrument has 
 
 Fig. 94. — Younger's scaler, enlarged. 
 
 a wide range of usefulness and probably is the safest and most efficient 
 type in the hands of inexperienced operators. 
 
 Files of various shapes, sizes and fineness of cut have been extensively 
 used in prophylaxis. D. D. Smith made use of a selection of fine and 
 coarse files (Fig. 95) , the shanks of which were bent at various angles. 
 A somewhat different set of coarse files has been suggested by Towner 
 
158 
 
 PREVENTIVE DENTISTRY 
 
 (Fig. 96), which are very effective in removing calcuh and smoothing 
 roughened enamel and cementum. When sharp, the file is rapid in its 
 action and covers a greater surface with each stroke than other forms of 
 instruments. In many respects it is the most universal in its applica- 
 tion and the easiest to master. The chief objection to this form of 
 instrument is that its broad surface does not give the delicate sense of 
 touch that is obtained by a smaller blade and as a result the operator 
 
 II U 13 14- 15 16 
 
 Fig. 95.— D. D. Smith's files. 
 
 may easily be deceived regarding the character of the tooth surfaces, 
 either leaving upon them thin plates of calculi or cutting too deeply into 
 the enamel or cementum. 
 
 The planing form of instrument (Fig. 98) , as designed by Carr, James 
 and Hartzell, constitutes a special and distinct type. These sets are 
 composed of 150 different instruments nearly all of which have a right 
 angle turn at their extreme tip. The blade is much heavier than 
 
 Fig. 96. — ^Towner's files. 
 
 that of the Tompkins type and is so made that it has a relatively 
 broad and flat surface on the extreme end of the right angle tip 
 which is intended to ride upon the surface of the tooth when in use. 
 The shanks are so shaped that when the flat 5nd is laid upon the tooth 
 and the shank rests upon some other surface of the tooth, the inner 
 edge of the blade acts after the manner of a draw plane or scraper when 
 pulled over the surface of the tooth (Fig. 98) . When used in this 
 
ORAL PROPHYLAXIS 
 
 159 
 
 manner these instruments will roi:iove all foreign and extraneous 
 substances from the enamel and cementum and by continued applica- 
 tion will shave or plane down these surfaces until they are smooth. 
 The large number of instruments in the set are arranged in groups of 
 
 Fig. 97. — Planing instruments. 
 
 eight which are so shaped that they readily adapt themselves to eight 
 positions on the tooth. The various sets of eight instruments are then 
 grouped according to curvature of shanks, straight, convex and con- 
 cave; according to size, small, medium and large; and according to 
 angle of inclination of shank to handle, namely narrow and Made angle. 
 The principle upon which these planes are built and their wide adapta- 
 
 FiG. 98. — Plane in positic n in tooth, enlarged. 
 
 bility to reach all tooth and root surfaces make them in the hands of the 
 skilled operator the most efficient of the available prophylactic instru- 
 ments. On the other hand, it is true that the technic of using these 
 complicated sets of planes is not'easily or quickly mastered and may be 
 
160 PREVENTIVE DENTISTRY 
 
 successfully accomplished by only those operators who give consider- 
 able attention to this method of practice. They therefore are not to 
 be recommended to the general practitioner who gives but a small part 
 of his time and attention to dental prophylaxis. Rather should he 
 adopt some of the simpler forms of instruments, to begin with at least, 
 and master their use to the best of his ability. With the Younger 
 type of instrument combined with files and small delicate sickles 
 valuable and gratifying results may be obtained. 
 
 As has been said, the selection of instruments is more or less a per- 
 sonal matter. It is not so important that one particular type be 
 selected, as that some suitable set be adopted and mastered by the 
 operator so that he may completely remove all extraneous deposits 
 from the teeth. This may be successfully accomplished in a large 
 percentage of cases by any of the above types of instruments. 
 
 Stains. — ^The great majority of stains on the teeth are extraneous to 
 the enamel, being glued to the surface by mucoid films. It follows 
 therefore that when all such films and deposits are removed from the 
 teeth, the stains will also be eliminated. This may be accomplished 
 by instrumentation alone or by the subsequent polishing of the tooth 
 surfaces. Many of the nostrums which are recommended for the 
 quick and ready removal of stains are dangerous and should be avoided. 
 They are frequently highly acid in reaction and depend upon a super- 
 ficial decalcification of the enamel surface to release the stain. These 
 highly acid preparations, therefore, etch and destroy the natural 
 enamel surface and frequently accomplish considerable damage as a 
 result of their use. 
 
 For a discussion of the handling of stains which have penetrated the 
 substance of the tooth or have diffused outward from the pulp, the 
 reader is referred to Chapter XL 
 
 Plaques and Films. — The various forms of mucinous and bacterial 
 plaques which cover all neglected and unclean surfaces of the teeth 
 are of as great importance as, if not greater than, the dental calculi. 
 It is in these films that the salivary calculi and stains first become 
 impregnated and are attached to the surface of the tooth. So also do 
 they afford an excellent medium for the propagation of oral micro- 
 organisms, many of which when growing in this manner, exert a harmful 
 influence upon the teeth and surrounding tissues. For instance, acid- 
 producing bacteria beneath a plaque may produce sufficient acid to 
 decalcify the enamel and form an initial lesion of caries. Other types 
 of organisms when growing in a plaque contiguous to the gums at the 
 neck of the tooth frequently exert a. toxic and irritative effect upon 
 these tissues, producing chronic gingivitis and a tendency toward 
 pyorrhea. It is therefore highfy essential that all plaques and films 
 
ORAL PROPHYLAXIS 161 
 
 be removed from the teeth by prophylactic measures and the patient 
 taught to prevent their recurrence by daily personal care. 
 
 When these films are infiltrated with stains or calcareous deposits 
 they may be recognized easily, but when they do not contain these 
 products they are colorless and invisible to the eye. In many instances 
 they may be detected by the particular injury which they produce or 
 by the employment of a stain which will reveal their location and 
 distribution. For this purpose a disclosing solution which has been 
 suggested by Skinner is very valuable. The formula is as follows: 
 
 lodin (crystals) 50 grains 
 
 Potassium iodid 15 " 
 
 Zinc iodid 15 " 
 
 Glycerin 4 drams 
 
 Aqua 4 " 
 
 If this stain be applied to the surfaces of the teeth and washed off 
 with a stream of water, all films and plaques will be highly colored by 
 the iodin and will stand out in bold relief to the clean portions of the 
 teeth which will be clear. This, or some other, efficient disclosing 
 solution should be used in the diagnosis of every case and in the 
 beginning and the close of all prophylactic treatments. In this 
 manner the plaques may be located to the end that in the subsequent 
 polishing of the tooth special attention may be given to their removal. 
 
 2. Smoothing and Polishing Tooth Surfaces and Fillings. — ^When 
 all deposits have been removed from the teeth, the surfaces of the 
 enamel and cementum should be smoothed and polished. Much of 
 this may be done with the same instrument with which the calculi are 
 removed by simply continuing to plane the tooth surfaces after they 
 are cleaned until they feel smooth and free from irregularities. Occa- 
 sionally the enamel surfaces are so rough and corrugated that the 
 ordinary scalers and files are not sufficient to smooth them. Especially 
 is this true of the enamel in the region of the gingival line which is 
 frequently pitted and roughened by the action of acids produced by 
 cervical fermentations. These may be smoothed by planing instru- 
 ments or by the judicious use of stones and discs. When the enamel 
 has been made smooth in this manner, it should be polished with XXX 
 Silex^ or with combinations of these two substances followed by tin 
 oxid. This may be done with orange wood sticks and porte polishers 
 (Fig. 100), vigorously rubbing all accessible enamel surfaces until a high 
 polish has been obtained. The interproximate surfaces are reached by 
 thin tapes and the wide floss carrying the polishing powder, care being 
 taken to prevent injury of the interproximate gum tissues. This process 
 
 1 XXX Silex may be obtained from the Bridgeport Wood Finishing Company, 
 Bridgeport, Conn. 
 11 
 
162 
 
 PREVENTIVE DENTISTRY 
 
 may be expedited by substituting an engine polisher for the hand 
 rubbing. For this purpose the common bell-shaped rubber cup should 
 
 Fig. 99. — Orange-wood stick and porte polishers. 
 
 never be used as it invariably injures the gingival tissues. There are 
 however, two types of rubber cups, namely, the Young B. S. polisher 
 
 Fig. 100. — B. S. polishers. 
 
 (Fig. 101). and the Davis Polishing cup (Fig. 102), which are so shaped 
 that they may be adapted to the labial and lingual surfaces of practically 
 
 Fig. 101. — Davis polishing cup. 
 
 all teeth and if used with care will do no injury to the gingival tissues. 
 By the use of this form of polisher together with soft felt wheels, a 
 
ORAL PROPHYLAXIS 
 
 m: 
 
 smooth and highly lustrous polish may be given to the labial and lingual 
 enamel surfaces in a comparatively short time. 
 
 In the process of polishing enamel surfaces it should be borne in 
 mind that the enamel covering of the teeth is a highly important 
 structure and should not be sacrificed ruthlessly. We have shown 
 elsewhere^ that the outer surface of well formed enamel is more dense 
 and impervious to fluids than a cut enamel surface can be made by any 
 form of polishing (Fig. 102). It is undesirable, therefore, to reduce the 
 surfaces of those enamels which are naturally lustrous and polished. 
 And those that are dull and rough should be smoothed and polished 
 with the least iiossihle loss of enamel surface. This may be accomplished 
 
 Fig. 102. — Section of tooth showing portion of enamel at {A) which had been ground 
 and polished, the normal enamel surface being shown at (5) . The tooth was immersed 
 in silver nitrate after polishing and by a comparison of the depth to which the stain 
 has penetrated the enamel it will be seen that the ground and polished portion {A) is 
 more porous than the natural surface {B). 
 
 usually by the removal of a layer of enamel not greater than the thick- 
 ness of writing paper. When the teeth are polished in this manner 
 with due regard for the conservation of enamel substance, no harm will 
 result to the dental tissues and an inestimable benefit to oral hygiene 
 may be accomplished (Figs. 103 and 104). 
 
 Care should be exercised to prevent the injury of the peridental 
 tissues in the process of tooth polishing. The heroic measures which 
 are practiced by over-enthusiastic exponents of preventive dentistry, 
 such as the ruthless cutting of the gingival and interproximate gum 
 tissues and the vigorous sawing between the teeth in the act of polishing 
 
 1 Bunting and Rickprt: Jour, Nat, Dent. Assn., January, 1917, p. 90, 
 
164 PREVENTIVE DENTISTRY 
 
 the enamel surfaces, are unwarranted and unnecessary. The teeth 
 may be made sufficiently smooth to be self-cleansing and oral hygiene 
 may be established by much more conservative measures than these 
 without any attendant injury to the peridental tissues. 
 
 Fig. 103. — Upper cuspid before and after polishing for five minutes in the manner 
 
 described in the text. 
 
 All fillings should be polished and made absolutely flush with the 
 tooth surfaces. A rough cervical filling may often act as a nidus for 
 the attachment of a bacterial plaque which may promptly reappear 
 after a prophylactic treatment. When the filling is made perfectly 
 smooth and polished, these surfaces may be kept clean and free from 
 localized fermentation. 
 
 Fig. 104. — Upper molar before and after polishing for five minutes in the manner 
 described in the text. 
 
 3. Detection and Filling of All Cavities. — ^At this stage of the process 
 careful search should be made for carious lesions in the teeth and all 
 necessary operative procedures should be performed. Indeed, the 
 early detection and treatment of these defects should always be a 
 matter of prime importance in preventive dentistry. It is the small 
 cavity which is most successfully handled and, if taken early, the 
 treatment is not complicated by pulp disturbances and devitalization. 
 
Oral prophylaxis 
 
 165 
 
 4. Restoration of Faulty Proximate Contacts and Contours. — Faults 
 in form and contour of teeth are very prolific causes of peridental 
 irritation and disease. When proximate cavities are repaired by 
 fillings which are not sufficiently contoured to afford a normal contact 
 with the adjacent tooth, food is crowded between the teeth in mastica- 
 tion and as a result the interproximate gum tissue (Fig. 105)/ is severely 
 injured. Normally these tissues are protected by tight contacts which 
 in mastication tend to deflect the food labially and lingually and all 
 proximate fillings should be made to reproduce these normal inter- 
 proximate relationships. The importance of this procedure cannot be 
 too strongly emphasized since those who have studied these conditions 
 have recognized that open and faulty contacts constitute the point 
 
 Fig. 105. — Models showing the injury to gum tissues arising from the lack of proper 
 interproximate contact. 
 
 of inception of a very large percentage of peridental infection. Opera- 
 tive dentistry, therefore, to be consistent with the principles of oral 
 hygiene, must be so constructed that all proximate contours will be 
 restored and the normal relationships of the teeth to each other 
 reestablished. 
 
 It is equally important that the buccal and lingual contours be 
 restored to the full normal curvature. A comparison of the normal 
 contours of teeth will reveal the fact that certain types possess far 
 more buccal and lingual contour than others (Fig. 106). It is also 
 evident that when these contours are pronounced, the buccal and 
 lingual gum tissues are protected from the injury from excursions of 
 
 1 Friesell, H. E.: The Dental Items of Interest, 1918, p. 977. 
 
166 
 
 PREVENTIVE DENTISTRY 
 
 food against them during mastication. But in case the contours are 
 fiat, considerable damage may be done to the gingival tissues by the 
 impaction of food during mastication. Instance of this may be seen 
 in Fig. 107 in which it will be noted that the gingival margin about the 
 
 
 Fig. 106. — Types of teeth showing natviral variance in buccal and labial contours. 
 
ORAL PROPHYLAXIS 
 
 167 
 
 lower central incisor has been torn and caused to recede, by virtue of 
 the fact that the tooth in question was flat on its labial surface and 
 did not protect the gingivae. A correction of this natural fault may be 
 made by the introduction of bulging cervical inlays which will afford 
 
 Fig. 107. — Retraction of labial gum tissues about lower central incisor resulting from 
 excursions of food over fiat labial surface of the incisor. 
 
 artificial food deflectors. Perhaps the worst offender in this respect 
 is the straight sided type of crown about which the gingival tissues 
 are constantly in a state of irritation. In contrast to these, we find 
 that properly shaped and adapted crowns as in Fig. 109 protect the 
 labial and lingual tissues and cause a minimum amount of irritation. 
 
 Fig. 1 
 
 5. Removal of All Overhanging Portions of Fillings, Crowns, Bridges, 
 etc. — ^Fillings which are not flush with the tooth surfaces, and cro^^^lS 
 which are not closely adapted to the teeth at the cervical region offer 
 considerable retention for food and infectious materials and constitute 
 
168 
 
 PREVENTIVE DENTISTRY 
 
 potent predisposing factors in both caries and peridental disease. 
 So frequent are these operative faults that scarcely a case is presented 
 which does not have one or more of them. In the practice of preventive 
 dentistry it is necessary, therefore, not only to conform all new restora- 
 tions to these principles, but also to correct the faults of all operative 
 procedures which have previously been made, even if it involves their 
 removal and replacement. It frequently happens, however, that by 
 the judicious use of files and chisels a faulty filling may be reshaped 
 and made to conform very closely to the normal contours of the tooth. 
 So, also, overhanging edges of porcelain crowns may often be reduced 
 by small pointed stones and made flush with the end of the root. By 
 these procedures such faulty restorations may cease to be a menace 
 and may be retained for many years of service. 
 
 >i*~; 
 
 
 i 
 
 . r 
 
 Fig. 109. 
 
 -Traumatic occlusion, upper right cuspid being forced outward and distally 
 by undue stresses arising from the loss of molar occlusion. 
 
 6. Relief of Undue Stresses. — It has been noted by operators who 
 have studied peridental diseases that many cases of pyorrhea begin 
 about teeth upon which there has been excessive and unusual stress. 
 In such cases it will be seen that when the jaws are brought into 
 occlusion, these teeth are moved laterally in their sockets by the gliding 
 of the inclined planes of opposing teeth, one upon the other. This is 
 noted frequently in the upper anterior teeth when because of the loss 
 of a large proportion of the molars and bicuspids, the bite has closed 
 and the lower incisors strike against the lingual surfaces of the upper 
 incisors to produce a pronounced traimaatic injury. As a result, the 
 peridental attachments on the lingual surfaces of the roots of these 
 teeth are broken down, the teeth become loosened and drift labially 
 until they elevate the upper lip and in extreme cases assume a position 
 practically perpendicular to their original inclination (Fig. 109). It is 
 of the greatest importance that all such cases of excessive incisal 
 
ORAL PROPHYLAXIS 169 
 
 occlusion be discovered early before serious damage and protrusion of 
 the teeth have been accomplished, as the correction of these faults 
 and restoration of the teeth to their normal position are extremely 
 difficult and as a rule impracticable. The treatment of such cases 
 consists of either raising the bite by the insertion of mechanical appli- 
 ances to restore missing posterior teeth or the shortening of the lower 
 incisors by grinding until they no longer strike the opposing teeth. 
 
 Traumatic occlusion may produce injury in the peridental tissues 
 about teeth other than the incisors. Fig. Ill is taken from a mouth 
 which had slight indications of pyorrhea save that of a deep pocket on 
 the mesial of the upper right first molar and the distal of the adjacent 
 second bicuspid. It will be noted that the lower first molar had been 
 
 
 4^^ 
 
 
 ^t ■' 
 
 
 
 
 HHtai 
 
 
 
 
 j| 
 
 ^ 
 
 
 
 II 
 
 1 
 
 H^..^*^.. 
 
 l| 
 
 ■ 
 
 Itaaa^ 
 
 
 ^^■^ 
 
 Fig. 110. — Deep pyorrhetic pockets on mesial of first molar and second bicuspid upper 
 due to traumatic occlusion of lower second molar. 
 
 extracted some time previously and the lower second molar was striking 
 the upper first molar at an unusual angle. The traumatism thus occa- 
 sioned, associated with a general lowering of tissue resistance, of which 
 there was evidence in this patient, resulted in a serious pyorrhetic 
 involvement of the teeth under stress. Numerous examples of injiu"y 
 from occlusal stress are to be found in susceptible individuals when the 
 cusps of the molars and bicuspids are high and closely interlock in 
 occlusion. In them it is found that the teeth stand in such a position 
 that as they are brought together in rest the cuspal planes do not 
 immediately fit, but that two inclined surfaces first strike together and 
 then slide into position producing a lateral shearing strain upon both 
 teeth. Unless the resistance of the peridental tissues is exceedingly 
 
170 PREVENTIVE DENTISTRY 
 
 high peridental injury and degeneration result which are very frequent 
 causes of pyorrhetic affections. 
 
 In oral prophylaxis, therefore, the mouth should be examined for 
 all undue stresses, especially when the cusps of the teeth are high and 
 closely interlocked. And in all operative procedures which involve 
 the reproduction of tooth form, such as fillings, crowns, bridges, etc., 
 it is highly important that they be so shaped that no unnatural or 
 unusual stresses be exerted by them upon the opposing teeth. Many 
 teeth have been loosened by an over-full filling and many a bridge 
 which was otherwise technically perfect has failed because of faults of 
 occlusion, which have resulted in traumatic injury and loss of attach- 
 ment of the peridental tissues about the abutments. So also, may 
 prosthetic appliances produce injury to the peridental tissues by exces- 
 sive pressure upon the soft tissues and lateral stress upon the teeth. It 
 is only by a full appreciation of these factors and a close study of the 
 stresses in each individual case that preventive dentistry may success- 
 fully be accomplished. 
 
 7. Protection of Sulci. — It is a matter of common observation that 
 the sulci of many teeth are attacked by caries very early. Especially 
 is this true in the case of those teeth which have high cusps and corres- 
 pondingly deep and more or less patent sulci. In these occlusal crevices 
 food and acid-producing bacteria are retained under very favorable 
 conditions for the inception of dental caries. Prophylactic measures 
 directed toward the protection of these extremely vulnerable areas 
 in the tooth consist of the cleansing of the sulci with picks and explorers, 
 dessication and fiooding with copper cement, or other suitable sub- 
 stance. In this manner the defect in the tooth will be filled by a 
 material that will exert a continued antiseptic and germicidal action, 
 in its immediate vicinity and will effectually protect the tissues against 
 caries invasion for a considerable length of time. This form of treat- 
 ment is especially beneficial in cases of children's teeth, if performed 
 immediately after the eruption of the tooth before the carious process 
 has set in. 
 
 8. Instructions to the Patient. — As we read the various opinions upon 
 the subject we find that a wide range of procedures is suggested by 
 dental practitioners to their patients as to the personal care of the 
 mouth. All agree that the daily personal attention to the cleansing 
 of the mouth and teeth is a matter of highest importance in preventive 
 dentistry. The most that may be done by the operator is to so organize 
 the mouth that dental cleanliness is made possible and then the future 
 course of the case is determined largely by the manner in which the 
 patient cooperates in maintaining oral cleanliness. Obviously patients 
 should first be given definite instructions as to the method by which 
 
ORAL PROPHYLAXIS 171 
 
 they should cleanse then" mouths, but as yet no uniform technic of 
 personal care has been agreed upon. Differences of opinion have been 
 expressed as to the armamentarium to be used, some preferring one 
 style of brush and others another style. Mobile a few have objected to 
 the use of any kind of a brush on the ground that they believe them all 
 to be harmful to the oral tissues and suggest in their place the use of 
 cotton rolls and swabs. The majority, however, agree that some form 
 of brush and flat floss should be employed although the manner of their 
 use is not generally agreed upon. So also is there variance of opinion 
 regarding the form of dentifrice that should be adopted, individual 
 preference ranging through the whole gamut of powders, pastes, and 
 dental lotions. The most comprehensive statement of the views of 
 leading workers in preventive dentistry was obtained by the Editor of 
 the Items of Interest and was published in the ]May issue of that journal 
 for 1915. In answer to a letter relative to the instruction which should 
 be given to patients, a variety of opinions and statements were received 
 which were compiled into a symposium upon that subject. To this 
 the reader is referred for a general view of what are perhaps the most 
 sane and conservative lines of thought on this subject. It is not 
 possible to discuss in this place all these various views, but rather a 
 particular course of procedure will be outlined which is selected from 
 various sovu"ces and which seems to the author to be well founded. 
 These views are suggested, not as measiues par excellence, nor as views 
 possessing any special virtue, for it is true that each of the various 
 operators is daily accomplishing excellent results in the mouths of 
 patients by the use of the particular method of oral prophylaxis T\^hich 
 he advocates, but rather are these measures stated as a simple workable 
 basis which may be taught easily to the patient and which has yielded 
 very beneficial results under the personal supervision of the author. 
 
 It must be recognized at the outset that the purpose of brushing the 
 mouth and teeth is two-fold; first, the cleansing of the oral cavity of 
 all food and bacterial plaques; second, the production of mechanical 
 friction upon the peridental gum tissues which mil stimulate the cir- 
 culation and harden and toughen the epithelium to the point that it 
 becomes highly resistant to mechanical injm-y. To accomplish these 
 ends not only the teeth but the gums as well should be brushed 
 vigorously with a hard stiff-bristled brush used in the proper manner. 
 
 Brushes. — Diuing recent years the matter of obtaining suitable 
 brushes has been a difficult one, due to the fact that the war has inter- 
 fered with the importation of the best brushes and materials for making 
 them. As a result, at the present time, there are on the market two 
 forms which are acceptable, one the Rolling Brush (Fig. 112) and the 
 other a brush designed by Dr. Card, of Philadelphia (Fig. 114). These 
 
172 PREVENTIVE DENTISTRY 
 
 brushes are said to be made from the bristles of the Russian boar, and, 
 as a rule, wear very well. They are made of three grades of bristles, 
 soft, medium and hard, of which the hard is usually to be preferred. 
 
 Fig. 111. — The Rolling brushes. 
 
 In the selection of a brush, the largest size that can comfortably be 
 adapted to the mouth of the patient should be chosen. The largest 
 size of these two forms may be used in the average adult mouth, while 
 the smaller forms are well suited to small mouths and those of children. 
 
 Fig. 112. — Dr. Card's brushes. 
 
 The method of using the brush should consist of two general types 
 of motion. The first is a sweeping stroke beginning on the gums and 
 continuing over the teeth in a direction parallel with the long axis of 
 the teeth, down on the uppers, and up on the lowers. The brush is 
 placed on the buccal surface of the upper jaws with the bristles pointing 
 up and the side of the brush lying against the teeth. By a rotary 
 motion of the hand the bristles are made to sweep down over the gums 
 
ORAL PROPHYLAXIS 
 
 173 
 
 and the teeth, m a vigorous manner, thereby stimulating the gingival 
 circulation and cleansing the buccal and a portion of the proximate 
 surfaces of the teeth (Fig. 113). On the lingual a similar motion is 
 used while on the lower a reverse motion is employed, namely, a 
 sweeping upstroke on the gums and the teeth. 
 
 To reach the cervical portion of the tooth and embrasures a special 
 stroke is used. This is accomphshed in case of the upper teeth, by 
 placing the brush with its side against the upper jaw with the bristles 
 
 Fig. 113. — Two views of downward stroke. 
 
 pointing down in a position exactly the reverse of the first described 
 method (Fig. 114). The brush is then carried %^% down over the 
 teeth in a lengthwise, shaving stroke so that the inner row of bristles 
 will be forced gently into the interproximate spaces and against the 
 cervical portion of the buccal surfaces. By repeated motions of this 
 order those portions of the teeth which receive the least friction by the 
 first method are rubbed and cleansed. This may be accomplished by 
 the use of the single row Rolling brush and by the larger multi-row 
 
174 
 
 PREVENTIVE DENTISTRY 
 
 brushes used in the same manner, one row of bristles only being made 
 operative. On the lower jaw the same motion is used in a reverse 
 manner. For the lingual surfaces a peculiarly shaped brush has been 
 
 Fig. 114. — Two \dews of interdental stroke. 
 
 Fig, 115, — The single row Rolling brush (above) and the Barnes lingual brush 
 
 (below) . 
 
ORAL PROPHYLAXIS 
 
 175 
 
 suggested/ which may be made from any celluloid-handled brush. 
 The head of the brush is cut off removing all but two rows of bristles 
 together with that portion of the celluloid handle which holds them. 
 The celluloid handle is then softened in boiling water and bent to the 
 shape shown in Fig. 116. With this brush the patient may effectually 
 cleanse a large portion of the lingual surfaces and the lingual embra- 
 sures, by a gentle shaving stroke. 
 
 Dental Floss. — It should be obvious that by no method of brushing 
 may the entire mesial and distal surfaces of teeth in close contact be 
 reached. For cleansing these surfaces of the teeth which are so fre- 
 quently attacked by dental caries, it is necessary that the patient be 
 taught to pass the flat floss into each interproximate space to wipe off 
 the two proximate surfaces. For this purpose the fiat dental floss is 
 much to be preferred over the round cord as it covers more surface and is 
 more effective as a cleanser of the teeth (Fig. 116). In this operation 
 
 Fig. 116. — Flat dental floss. 
 
 great care should be exercised to prevent the snapping of the cord against 
 the interproximate gum septa for in this manner an over-zealous or 
 careless patient may do serious harm to the soft tissues. The floss, 
 therefore, should be held with the fingers of the two hands, exposing 
 but a short segment of the cord and by a gentle sawing motion it should 
 be carried beyond the point of contact (Fig. 117). Then the mesial and 
 distal surfaces should be gently and carefully wdped to rid them of 
 food and bacterial plaques, but in no case should the floss be sawed 
 or manipulated in a rough or vigorous manner. If ordinary care is 
 used in the instruction of the patient this procedure will do no harm 
 to the gum tissues but, on the contrary, will serve as an active and 
 effective means of combating interproximate caries and gingivitis. 
 
 Dentifrices. — ^The question of dentifrices is one about which there 
 has been considerable discussion. At the present time, however, there 
 is little accurate information on this subject. For the most part, the 
 
 Dr. Henry Barnes, Clevel9.nd 
 
176 
 
 PREVENTIVE DENTISTRY 
 
 dental profession has depended upon, and recommended, the various 
 dental preparations which have been placed on the market and widely 
 advertised without any definite knowledge of the ingredients of which 
 
 Fig. 1 17. — Carrying dental floss between the teeth. 
 
 Fig. 118. — Passing floss over mesial surface of bicuspid. 
 
 they are composed or the action which they exert when used. In a 
 former communication^ we published microphotographs showing the 
 shape and character of the grits contained in a number of the popular 
 dentifrices. At that time we called attention to the fact that certain 
 
 1 Bunting and Rickert: Jour. Nat. Dent. Assn., August, 1915, p. 247. 
 
ORAL PROPHYLAXIS 111 
 
 of these preparations are highly abrasive and rapidly cut the enamel 
 especially when a crosswise stroke of the brush is used. On the other 
 hand, many contained almost no abrasive materials and were exceed- 
 ingly bland in their action. 
 
 It is the opinion of the author that no one dentifrice should be 
 invariably adopted. Rather should a type of preparation be selected 
 which is best adapted to each individual case. In the preparation of a 
 mouth for preventive dentistry, a strongly abrasive dentifrice may be 
 prescribed which will assist materially in smoothing the tooth sm-faces 
 and in ridding the mouth of fermentation. When the mouth is under 
 control, it will be found that oral cleanliness may be accomplished by 
 less harsh measures. Then the patient may be given a smoother 
 preparation by which he can maintain the tooth surfaces in a highly 
 polished and clean state. Occasionally cases are presented in which 
 the viscosity of the oral fluids tends to make the cleansing of the mouth 
 so difficult that the bland dentifrices are inadequate. For them a 
 coarser preparation should be prescribed to be used either alone or 
 alternately with the finer form. In all such cases special supervision 
 should be given to see that damage to the tooth and peridental tissues 
 does not occur as a result of the abrasive action of the dentifrice. 
 
 As to the various dental lotions and mouth washes which are on the 
 market, it is the opinion of the author that none of them possess very 
 essential therapeutic action and all of them are of doubtful value. 
 Occasionally, when considerable hypertrophy of the soft tissue has 
 taken place, the zinc chlorid preparations, as Astringosol and Lavoris, 
 may be used for a short time to assist in reducing the inflammation, 
 but as soon as this has been accomplished they should be discontinued. 
 It must be remembered also that these preparations are impotent 
 when used alone and act only as simple adjuvants to the necessary 
 operative and surgical measures by which the local irritants must be 
 removed before the swelling and inflammation may be reduced. If a 
 dental lotion is desired, a 5 per cent, salt solution or a one-half satiu^a- 
 tion of lime water may be used to good advantage. The salt solution 
 seems to act as a tonic to the gum tissues as well as a detergent to cleanse 
 the teeth. The lime water, although not so palatable, is useful in that 
 it softens the mucinous plaques and by its alkalinity tends to neutralize 
 any acids which may be present. 
 
 9. Sustaining Supervision. — ^\Vhen a mouth has been reorganized as has 
 been outlined and the patient has learned how to care for it properly, 
 a complete change in the oral picture will be noted. Instead of the 
 fermentations and general uncleanliness which previously had existed, 
 the teeth appear clean and polished and the giuns are hard and firmly 
 resistant. If the patient continues to perform the dut}^ of daily cleans- 
 ing, the mouth will remain in this improved state of oral hygiene. But, 
 12 
 
178 PREVENTIVE DENTISTRY 
 
 as a rule, even the most careful cooperation on the part of the patient 
 is not sufficient to reach all the siufaces of the teeth and gums and in 
 time there will be fresh collections of food, bacterial plaques and other 
 concretions in those localities which have received the least care. For 
 the permanent maintenance of oral hygiene and preventive dentistry, 
 it is necessary that the patient be seen occasionally for the purpose of 
 assisting him in the care of those most difficult places, to note and 
 correct any beginning gingivitis and to discover any new cavities which 
 may have appeared. To this end simple measures of prophylaxis are 
 necessary which may be accomplished in from twenty to thirty minutes. 
 They should consist of the exploration of the cervical areas and gingival 
 crevices with a small Younger type instrument searching for and remov- 
 ing all accretions. The surfaces of the teeth may then be lightly 
 gone over with the engine cup and one of the abrasive dental pastes 
 followed by the use of the dental floss upon the proximate surfaces. 
 This, with a direction of the attention of the patient to certain places 
 in the mouth which need special care is all that usually is necessary. 
 The frequency of these sustaining treatments should be determined by 
 the nature of the case. Some will need to be seen once each month 
 while others may safely be allowed to go two and three months without 
 attention by the operator. 
 
 From the necessarily lengthy detailed description of this programme 
 of preventive dentistry, the reader may be led to think that the per- 
 formance of these measures is a long and tedious process. In cases 
 which require considerable reorganization of fillings, crowns, bridges^ 
 etc., it is true that considerable time may be consumed in preparing 
 the mouth so that it may be kept in a hygienic condition. But all the 
 necessary cleansing and polishing of the teeth usually may be accom- 
 plished in a relatively short time by the method suggested, not more 
 than two to four hours all told. To many, this may seem inadequate, 
 but by actual experience covering a large number of cases the author 
 has been convinced that very beneficial results may be obtained by the 
 expenditure of time which is not beyond the reach of the average 
 practitioner. Indeed, for a given number of cases in a busy practice 
 the institution of these measm-es should result in an actual saving of 
 time as mouths which are so reorganized will have far less dental and 
 peridental disease to be treated as time goes on. 
 
 The working details of the procedures which we have just described 
 or the benefits which are to be derived from them can never be fully 
 appreciated by an operator until he has faithfully applied them to a 
 variety of patients, has carefully worked out his own method of obtain- 
 ing the result and has watched the resultant changes which occur in 
 the mouths so treated. Then and only then will he fully understand 
 the principles of preventive dentistry and oral hygiene. 
 
CHAPTER IV. 
 
 INSTRUMENTATION, CAVITY PREPARATION AND THE 
 
 FILLING OF TEETH WITH GOLD FOIL, GOLD 
 
 INLAYS, AMALGAM, CEMENTS AND 
 
 GUTTA-PERCHA. 
 
 By JOHN V. CONZETT, D.D.Sc, 
 
 AND 
 
 ROSCOE H. VOLLAND, M.D., D.D.S. 
 
 Operative dentistry consists of all operations that are performed 
 upon the natural teeth and the tissues directly connected with them, but 
 the modern use of the term confines it to the operations that are per- 
 formed upon the teeth themselves, to correct the damage done by caries, 
 accident, and unusual wear of the surfaces of the teeth in mastication. 
 Crowns, regulations, and all restorations of teeth that have been lost, 
 are allotted to other departments of the profession. In this paper 
 operative dentistry will mean all operations that are made upon the 
 natural teeth that have for their purpose the restoration of lost tooth 
 tissue by means of fillings or inlays. The terminology and presentation 
 of the subject given to the profession by Dr. Black will be very largely 
 followed. 
 
 Cavity preparation is fundamental to all operations on the teeth, 
 and as the basic principles are the same for all materials and methods, 
 first the science of cavity preparation and the principles governing the 
 same will be taken up; then, the various materials with which to fill 
 the cavity will be considered with such exceptions in the preparation as 
 the physical characteristics of the material may demand. 
 
 Fundamentally, all cavities are the same no matter what may be the 
 material with which they are to be filled or what method may be used 
 to make the filling whether it be a filling of gold or one of the plastics 
 or whether it be an inlay of metal or porcelain. The only devia- 
 tion from the principles that will be laid down is that which may be 
 made imperative by the method used in the filling. For instance, in 
 the inlay, it will be impossible to use any retention that would make an 
 undercut of any description, for to do so would prevent the making of 
 a model or pattern that would fit the cavity; in the making of a porce- 
 lain inlay or a silicate filling, it will not be advisable to bevel the cavo- 
 surface angle, for the lack of edge strength of those materials would 
 
 (179) 
 
180 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 militate against the use of the bevel, as that would leave a thin edge of 
 the filling material at the margin of the cavity that would soon break 
 away and leave a vulnerable spot for the beginning of a recurrence of 
 decay. In nearly every respect, the principles may be applied to all 
 materials and methods, and in whatever case it is thought advisable 
 to depart from the principles here laid down, it will be emphasized in 
 the consideration of that particular method or material. 
 
 The first thing that the student should do in attempting to fill a 
 cavity is to study the conditions that surround the making of such an 
 operation. He should have a clear idea of the cause of the decay, 
 whether it was due to a defect in the tooth, as in a pit or fissure cavity, 
 whether it was a lack of cleanliness on the part of the patient, as in all 
 smooth surface cavities, and particularly cavities occurring in the gingi- 
 val surface of the teeth, or whether it was due to some mal-occlusion 
 that prevented the proper cleansing of the portion of the tooth in which 
 the initial penetration occurred. It is known that if it were possible 
 to keep the teeth surgically clean they would not decay, and it is knowu 
 that there are areas of susceptibility and areas of comparative immunity 
 upon the surfaces of the teeth. It is also recognized that the areas that 
 are most susceptible are those that are the hardest to keep clean by the 
 natural use of the teeth in eating. Therefore, if it were possible to keep 
 all of the surfaces of the teeth in the condition of the immune areas 
 there would be no decay. In our study of the conditions surrounding 
 the cavity in a tooth we should consider its position in relation to the 
 area of susceptibility or of immunity; whether the patient is negligent 
 in the care of his teeth or whether the cavity occurred, notwithstanding 
 that the most careful attention had been given to them. The operator 
 should carefully study the occlusion of the teeth, for he will not be able 
 to lay out intelligently his retentive and resistance cavity forms unless 
 he is familiar with the stress that will fall upon the filling that he is 
 going to place in that particular cavity. All men do not exert the 
 same degree of stress in mastication. One patient will bite with a 
 force of from 250 to 300 pounds as measured by the gnathodynamom- 
 eter, while another one will only exert a pressure of from 75 to 100 
 pounds. It would be inadvisable to cut as deeply for retention in 
 the case of the man with the weak bite as in the case of the man 
 with the strong one, and if, on the contrary, the same retention were 
 made for the man with the strong bite that you would think sufficient 
 for the weak one, you would invite failure by reason of a lack of enough 
 resistance on the part of the filling. It will be seen, then, how necessary 
 it is to study the conditions that caused the initial decay that we may 
 try to so make the filling that there will be no recurrence of decay, and 
 that the strength of mastication will not destroy the filling. If the 
 
CAVITY PREPARATION AND THE FILLING OF TEETH 181 
 
 student will make it a habit to study carefully the conditions surround- 
 ing the teeth upon which he is to operate, and will then apply the 
 principles of scientific cavity preparation to those conditions, he w^ill 
 have the pleasure of seeing his operations maintain themselves against 
 all of the natural usages of the teeth for long years to come, but neglect- 
 ing to do so will be disastrous and in the end will make him a failure in 
 his chosen profession. 
 
 After a thorough examination of the teeth they should be well cleaned. 
 If possible a thorough prophylactic treatment should be instituted 
 before any operations are attempted, for the reason that most patients 
 who present for the treatment of carious teeth have mouths that are 
 ill cared for, and the attempt to place the rubber dam upon such teeth 
 will drive many pathogenic organisms under the gingival margin, with 
 a very probable gingival irritation, if not a serious infection. If by 
 reason of an aching tooth such procedure is not possible, and it is found 
 necessary to make immediate attempts at relief, the teeth to be treated 
 should be cleaned as well as possible. The debris should be removed 
 by forcing an antiseptic spray about the gingival margin, painting the 
 gums with the tincture of iodin and then applying the rubber dam. 
 But the dam should never be forced upon a tooth that is unclean for 
 fear of infecting the gum tissue. During the cleansing of the teeth 
 an examination pad should be at hand to mark all of the defects that 
 will reveal themselves during the cleansing operation, and this tablet 
 should then be filed away for reference as the w^ork progresses. 
 
 An artist must have good instruments to accomplish good work and 
 a dentist is no exception to that rule. The authors are not of those 
 who believe in multiplying instruments; indeed, they believe that the 
 least number of instruments that will perfectly accomplish the desired 
 result is the ideal. In the multiplication of instruments beyond that 
 necessary for the accomplishment of the desired operation is the 
 multiplication of confusion. The student should thoroughly acquaint 
 himself with every instrument in his cabinet and know just where, 
 w^hen and how best to use that instrument and make every instrument 
 accomplish as much of the operation as possible. The reason that so 
 many operators are slow and sloven in their work is that they are 
 slaves to their instruments and can only accomplish a very little with 
 any instrument, and w^hen that little is done, must, perforce, find 
 another slightly different in design, in order to finish the operation. 
 The real artist will accomplish more with a piece of chalk and a shingle 
 than will a bungler wdth the finest outfit possible; therefore, every 
 student should be the master of a few instruments and add to that list 
 those that experience demonstrates are necessary and then master 
 those. 
 
182 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 Fig. 119. — Woodbury-Crandall instruments for cavity preparation. Nos. 1 and 2 are 
 hatchets for forming angles in the anterior teeth. Nos. 3, 4 and 5 are obtuse angle hoes. 
 Nos. 6 and 7, right angle hoes, instruments of the widest application in cavity formation. 
 Nos. 8, 9, 10 and 11, are right and left angle forming instruments, designed especially for 
 carrying out the sharp line angles in cavities, particularly in the anterior teeth. Nos. 12, 
 
CAVITY PREPARATION AND THE FILLING OF TEETH 183 
 
 A good mirror, several pairs of pliers, and five or six explorers must 
 be at hand to begin any operation. 
 
 The set of cutting instruments that were designed and selected by 
 Drs. Woodbury and Crandall are admirably adapted to the use of 
 student and dentist as well. These cutting instruments have been 
 selected with a view of obtaining the greatest service with the least 
 number of instruments. We append the description given by the 
 makers of the selection. 
 
 The engine instruments that will be necessary are round burs Nos. 
 2, 4 and 6, inverted cone burs Nos. 33|, 35, 37 and 39, fissure burs 
 Nos. 57, 58 and 59, and cross-cut fissure burs Nos. 701, 704 and 
 705. These should be for both the straight and contra-angle hand 
 pieces. In addition to the burs, there should be a sandpaper disk 
 mandrel for straight and right angle and a good assortment of 
 carborundum and gem stones. 
 
 Round. 
 
 Inverted cone. 
 
 Taper, 
 square end. 
 
 Fissure, 
 square end. 
 
 35 
 
 37 39 
 
 Fig. 120 
 
 57 58 59 
 
 Every student should know how to care for his instruments, for a good 
 workman is known by the condition of his tools. Duplicate sets should 
 be in the case of every operator as soon as he begins active practice, so 
 that an instrument once used may be discarded and not placed in the 
 operating case again until it has been sharpened and sterilized. 
 
 13, 14 and 15 are right and left, mesial and distal, gingival margin trimmers. Nos. 16, 17, 
 18, 19, 20, 21, 26 and 27 are right and left spoon excavators. Nos. 22 and 23, 24 and 25 
 are right and left enamel hatchets for breaking down enamel and shaping cavity walls in 
 bicuspids and molars; one of each pair is marked with a ring to distinguish the direction 
 of cut without examination of the cutting edge. Nos. 28 and 29, 30 and 31 are front and 
 back cutting enamel chisels; one of each pair is marked with a ring so that those which 
 cut on the back may be distinguished from those which cut on the face without examina- 
 tion of the cutting edge. Nos. 32 and 33 are special instruments for cutting mesially and 
 distally in molar cavities that are difficult of access. Nos. 34 and 35 are finishing knives, 
 designed for finding and removing overlaps along the gingival margin of fillings on the 
 proximate surfaces. Nos. 1 to 11, 22 to 25, and 32 and 33 have five cutting edges. The 
 sides of the blade, as well as the end, are sharpened. These additional surfaces are used 
 for push and pull cutting in the final smoothing of axial walls. After the end of the instru- 
 ment has been used in the preparation of the wall, the same instrument, with only a 
 slight change of the hand to bring the side of the blade into position, is used to remove the 
 slight irregularities left by the overlapping cuts of the end of the instrument. The enamel 
 instruments, Nos. 22 to 25, and 28 to 31, have a special temper differing from that of the 
 other instruments of the set. On account of their special hardness, they are not only 
 better suited for removing enamel, but will hold their edge longer. 
 
184 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 All burs should be thrown away as soon as they begin to lose their 
 edge. Nothing is more discouraging to an operator or more painful 
 to the patient than an attempt to operate with a dull bur. The best 
 possible obtundent to sensitive dentin is sharp instruments and their 
 proper use. 
 
 In sharpening the hand instruments, a large flat carborundum stone 
 of the finest texture is the best that the authors have found. The 
 stone should be five or six inches long and two or three inches in width. 
 
 The instrument to be sharpened should be held in the hand at the 
 proper angle, with a pen grasp; guiding the hand with the last knuckle 
 of the little finger, the instrument should be drawn the whole length of 
 
 Fig. 121. — Showing proper method of sharpening instruments, using a large stone, 
 the right method of holding the instrument, and the finger guide on the stone as the 
 instrument is drawn across it. 
 
 the stone with a firm pressure. If the instrmnent is not too dull, one 
 or two passes over the stone will sharpen it; but if it has completely 
 lost its edge, the drawing over the stone will have to be repeated until 
 a perfect plane is reproduced. Care should be exercised that every 
 pass of the instrument is at the same angle or there will be a dif- 
 ferent facet upon the edge of the tool for every passage over the stone 
 that the instrument has made. The edge on a dental instrument should 
 be as good as that on a carpenter's plane, and fully as sharp, and 
 the student should never rest content until he is able to reproduce such 
 an edge upon his instruments and keep it there, for unless he does he 
 will not be able to do good work. 
 
 All instruments should be scrupulously clean and should never be 
 
CAVITY PREPARATION AND THE FILLING OF TEETH 185 
 
 used upon a patient until they have been carefully sterilized and 
 sharpened. 
 
 In the preparation of the cavity and the making of a filling of any 
 kind it is best to apply the rubber dam for the following reasons: 
 
 (a) It provides a dry field of operation. 
 
 (6) It holds lips, cheeks and tongue away so that a free view^ of the 
 field of operation may be secured. 
 
 (c) The cuttings and debris produced in excavating the cavity are 
 easily and quickly removed by a blast of warm air. 
 
 {cl) The extreme limits of superficial decay can be made out only on a 
 practically dry tooth surface. This decay will appear as a dull white 
 chalky area on the enamel margin. 
 
 (e) The partial drying of the cavity reduces the sensitivity of the 
 dentin to cutting instruments. 
 
 (/) Since the cavity is mechanically cleansed and cut into sound 
 dentin in excavation the minimum of any infective material is left. 
 Saliva is continually charged with microorganisms, and it is not desir- 
 able to permit it to enter a cavity after the excavation is complete. 
 
 The dam should be medium heavy; a light dam is very undesirable. 
 A dark-colored, medium weight dam is preferred for the reason that the 
 dark-colored one will better reveal the holes punched in it for the 
 reception of the teeth. This is a great convenience, for if a light dam is 
 used the holes in it are difficult to find and a great deal of time is wasted 
 in attempting to do so. 
 
 The hole in the dam should be punched in a manner to correspond 
 with the position of the necks of the teeth in the curve of the arch, so 
 that the fit of the dam may be obtained without any wrinkles or 
 stretching of the rubber. It is good policy to start always at the 
 median line no matter how far back in the mouth the tooth that is to 
 be operated upon may be, for the reason that the method of having 
 many teeth through the dam assists in holding it away from the 
 field of operation, makes the work of the operator easier and gives 
 him better vision. 
 
 Before placing the dam, spray the mouth and teeth with an antiseptic 
 solution to remove any debris from around and between the teeth. 
 Then go between all of the teeth to be isolated with a piece of floss silk, 
 to see that the dam will be able to pass between them. If an}^ obstruc- 
 tion in the shape of food debris is there it will be dislodged, and any 
 sharp cavity margins that would cut the dam will be revealed and can 
 then be removed with a thin saw blade or sandpaper strip. If this is 
 not done, difficulty will be experienced in getting the dam in place and 
 the possibility of cutting the rubber is very great. 
 
 With the teeth prepared for the reception of the dam and the proper 
 
186 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 number and arrangement of holes punched in it, it is ready to be placed 
 in position. In order to facilitate its passage between the teeth, coat 
 the holes with soap or vaselin. Some operators have a piece of hard 
 soap whittled into an elongated cone, and just before placing the dam, 
 moisten the soap and insert the cone into each hole in the rubber, 
 thus coating the sides of the hole with a film of soap and lubricating 
 the rubber so that it slides over the teeth more easily. Perfumed 
 vaselin or oil may be used for the same purpose and will be as effective 
 and more pleasant to the patient. 
 
 The dam should be grasped with both hands and the first hole in the 
 rubber placed over the central incisor. When that is perfectly in place, 
 pass on to the lateral and so on until all of the teeth to be isolated are 
 in position; then place a properly selected rubber dam clamp over the 
 tooth farthest back and the fastening of the rubber dam retainer will 
 complete the operation. It is very convenient to have two dam 
 holders, the first, the usual double grasp holder for use against the 
 cheek, and the second, a single grasp one that will be placed on the 
 dam below the usual double grasp holder and passing back of the 
 neck be attached to the same position on the other side, thus firmly 
 holding the dam down on the chin and preventing the lower portion of 
 the dam from coming up, getting into the way and within the range of 
 vision of the operator. 
 
 If the incisors are the teeth to be operated upon it will be advisable 
 to include all of the incisors in the dam, and if the cavities are in the 
 distal surface of the central or in the laterals or cuspids, it will be well 
 to carry the dam as far as the bicuspids, using a clamp on the bicuspid 
 to hold it in place. If the dam has been properly placed it will not be 
 necessary to ligate the teeth, but the edges may be turned in under 
 the gum by slipping a piece of floss silk between the teeth and insinuat- 
 ing it under the dam and turning the edges under, which will help to 
 retain the dam in position. The teeth and dam should be thoroughly 
 washed with alcohol and dried with a blast of warm air. This will 
 remove any oily or muciferous material, will cause the dam to cling 
 tightly to the teeth and will do much to prevent dislodgment. It may 
 sometimes be necessary to ligate the teeth that are to be operated upon. 
 In doing so it will be found very convenient to use the Wedelstaedt tie. 
 
 This is made by throwing a double loop of silk around the tooth and 
 then uniting the ends with a surgeon's knot. This tie has the advan- 
 tage that it will not slip as you make the knot, because the double 
 thread will hold the silk firmly in place while the tie is being made. 
 Instead of pushing the silk under the gum with an instrument, it will 
 be found advantageous to place the ends of curved pliers between the 
 silk loop and the gum and then place the ends of the pliers under the 
 
CAVITY PREPARATION AND THE FILLING OF TEETH 187 
 
 gum, making traction on the ends of the silk, which will cause the loop 
 to follow over the curved ends of the pliers and slide off them under 
 the gum margin, where it will be held in place while the silk is drawn 
 tight by making firm traction on the ends. 
 
 A number of rubber-dam clamps should always be on hand and one 
 suitable to the case selected before attempting to place the rubber. 
 If an assistant is at hand it will facilitate the placing of the dam to 
 have her set her finger on the lingual surface of the last tooth to be 
 included in the isolated field and hold the dam in place while you fit 
 the clamp, or she may be trained to use the rubber-dam forceps and 
 place the clamp on the tooth after you have adjusted the dam. If an 
 assistant is not available the finger and thumb of the left hand may be 
 used to hold the dam in position while the forceps are used in the right 
 hand. 
 
 Fig. 122. — Surgeons' knot, also Wedelstaedt tie. 
 
 Another method of adjusting the dam in difficult posterior positions 
 is to cut the holes in it as usual, select the proper clamp and then insert 
 it into the last hole in the dam, grasp the clamp with the forceps and 
 place it over the tooth indicated in the isolation scheme. The rubber 
 will have to be somewhat rolled up and kept in the hand so that the 
 tooth to be clamped will not be obscured. When the clamp is in place 
 draw the rubber over it and over the tooth and then come forward and 
 include the other teeth to be isolated in sequence until all have been 
 included, when the retainers may be applied and the operation con- 
 tinued. 
 
 A w^ell defined plan should always precede any operation and the 
 student will find that if he will adopt and follow a system that is 
 rational he will make more progress and become more efficient than he 
 possibly could by the hit-and-miss fashion of operating. The system 
 given to the profession by Dr. Black will be followed in this treatise: 
 
 First, obtain the required outline form. 
 
 Second, obtain the required resistance form. 
 
188 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 Third, obtain the required retention form. 
 
 Fourth, obtain the required convenience form. 
 
 Fifth, remove any remaining carious dentin. 
 
 Sixth, finish the enamel wah. 
 
 Seventh, make the toilet of the cavity. 
 The outline form is the first portion of the operation to engage the 
 attention of the student, and he should learn to visualize the finished 
 filling before he makes the first move in the preparation of his cavity. 
 If he will learn to do this and have a well-defined plan to carry out his 
 vision he will soon become very adept in his operations; but if he has 
 no plan in mind and simply cuts away until his cavity bears some 
 semblance of a proper shape he will waste time and effort, and will, in 
 the end, obtain a very inferior result. The outline form comprehends 
 the doctrine of extension for prevention and the esthetic form. 
 
 Extension for prevention is the method of making the outline of the 
 cavity in such a manner that all of the margins thereof will be in an 
 area that is relatively immune to decay. 
 
 We stated in our preliminary remarks that there were areas of sus- 
 ceptibility and areas of relative immunity to decay. The areas that 
 are susceptible are all of the defective portions of the teeth, as open pits 
 and fissures, and those portions of the smooth surfaces that are not kept 
 clean. Decay begins by the invasion of the dental tissues by micro- 
 organisms attaching themselves to a surface of the tooth that is 
 not disturbed covering themselves with a gelatinous membrane 
 technically called the bacterial plaque. Under the protection of this 
 plaque they live upon the carbohydrates that are derived from the food 
 debris left around the teeth, and from which they elaborate lactic acid, 
 which attacks the cementing substance of the enamel. When the 
 enamel rods are broken and fall out the organisms have direct access 
 to the dentin, the destruction of the tooth is then rapid, and, if not 
 stopped, complete. The susceptible areas are those that are not 
 reached by the food in its excursions over the teeth in mastication or by 
 the movement of the tongue and lips, or not kept clean by the patient 
 in his toilet of the mouth. The proximate surface of a tooth, 
 especially that portion lying immediately gingivally to the contact 
 point, is the area of greatest susceptibility, and there will be found the 
 large majority of the cavities occurring in the smooth surfaces of the 
 teeth. As the point of greatest susceptibility is left and progress 
 toward the buccal and lingual angles is made, a lessening degree of 
 susceptibility is found until, when the angles are approached, we will 
 find a territory that is practically immune. The same may be said of 
 the march toward the occlusal and gingival margins until upon the 
 occlusal surface there is immune territory. Decay is never found upon 
 
CAVITY PREPARATION AND THE FILLING OF TEETH 189 
 
 the occlusal or incisal surfaces unless there is a defect in the enamel. 
 Also, toward the gingival margin susceptible territory is in evidence 
 until the cavity is carried under the free margin of the gum. On the 
 buccal and labial surfaces we will find an area of susceptibility at the 
 gingival margin and as far toward the occlusal surface as the curve of 
 the tooth will make difficult the scouring action of the bolus as it passes 
 over the tooth in chewing. The tooth with a large bell-shaped crown 
 will have a larger area of susceptibility at the gingival margin than a 
 tooth of more flat outline, occluso-gingivally, for in the case of the tooth 
 with a bell-shaped outline the belling of the tooth will cause the bolus 
 to miss the gingival portion, while if this surface were more flat the 
 food would have a scouring action over the entire buccal surface. 
 Also, in the bell-shaped tooth the curve of the bell will have a tendency 
 to prevent the frictional action of the muscles of the cheek upon the 
 gingival portion of the tooth, while in a tooth with a more nearly flat 
 surface the cheeks would move upon the entire buccal surface, with a 
 tendency to keep bacteria from making a lodgment upon them. As we 
 have said, the occlusal surfaces of the teeth are naturally in immune 
 territory, for the mastication of food would eft'ectually prevent any 
 organism from attaching itself to this surface; but, unfortunately, we 
 will frequently find here defects in the closure of the enamel plates 
 making pits and fissures into which the organisms of decay may 
 penetrate and find themselves immune from the frictional action of 
 mastication. 
 
 Finding that decay begins in certain territory and that it is rarely 
 if ever found in other areas, it is evident that if a recurrence of decay 
 is to be prevented around a filling that is made to correct the ravages of 
 decay the conditions that were responsible for the initial penetration 
 must be corrected. In order to do that the susceptible area will have 
 to be restored with a material that will be immune to the action of the 
 organism that caused decay and that material will have to be carried 
 far enough out of the susceptible area to prevent a recurrence of decay. 
 If this is not done it will make no difference how well the filling is made 
 nor how perfectly it may be adapted to the walls of the cavity. There 
 will be a recurrence of decay around it, not because the organism can 
 penetrate between filling and tooth, but because the original fault was 
 not wholly corrected. The organisms may find a hospitable territory 
 immediately next to the filling upon the surface of the tooth, and a 
 bacterial plaque being established in that position there will be a new 
 decay started, which will in time undermine the filling, and the whole 
 work will be destroyed. 
 
 In obtaining the outline form it will be seen then that it is necessary 
 to carry all of the margins of the cavity into areas of relative immunity 
 
190 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 to decay. The fact is that in large cavities the decay has practically 
 solved the outline form for the operator, for the penetration of the 
 carious process has been so great that the cutting necessary to lay the 
 cavity in sound tissue will usually find the margins in the area of 
 immunity. It means that the margins must be carried buccally and 
 lingually far enough out of the embrasures so that the margins of the 
 filling will not be in contact either with the proximating tooth or with a 
 filling in the tooth, and will therefore be kept clean by the progress of 
 the food over the tooth in mastication. In cavities in the incisors it 
 will be necessary to carry the margin far enough lingually and labially 
 so that the margins of the filling will be free of proximate contact. In all 
 cavities in the proximate surfaces it will mean the carrying of the lines 
 of the cavity margins below the free margin of the gum. In the case 
 of cavities in the occlusal surfaces of the teeth it will mean that all of 
 the pits and fissures will be cut out to their entire extent and that the 
 margins of the cavity will lie in smooth, sound territory. In short, 
 extension for prevention means the carrying of all margins of the cavity 
 into territory that can be kept clean by the natural functions of the 
 teeth, tongue and lips and under the free margin of the gum. 
 
 The esthetic form is that form which we give to the outline of the 
 cavity that will, to the greatest extent, preserve the beauty of the tooth. 
 A dentist should be an artist as well as an artisan, and it is his duty, and 
 should be his pleasure, to make all of his operations as beautiful as 
 possible. The highest art is to hide the art and make it appear natural, 
 therefore in the making of a filling it is of the utmost importance to hide 
 the restorative art as much as may be possible without the sacrifice of 
 utility or the ultimate preservation of the tooth. When utility and 
 esthetics come into direct antagonism, as they frequently do in the 
 making of restorations with gold, the usefulness of the masticatory 
 organ is paramount to the looks of the same and the tooth must be 
 preserved in spite of the lack of perfect color harmony. In short, when 
 the health and strength of the tooth demand the showing of gold, 
 do not hesitate to show it. Whenever possible make all of the opera- 
 tions with as little show of the filling material as practicable. Make 
 the outline form in such a way that the greatest mass of gold will be 
 out of the line of vision and preserve all of the enamel possible, thus 
 preventing the disfiguring display of gold. But lest it be misunder- 
 stood, let it be repeated, never under any circumstances hesitate to 
 display the gold when the preservation of the tooth demands it. 
 
 All of the external lines of the cavity should be slightly curved. 
 Nature abhors an angle, and a sharp angle on a filling is inharmonious 
 and very objectionable; therefore always round all angles that come 
 within the range of vision. Internal angles should be sharp in order 
 
CAVITY PREPARATION AND THE FILLING OF TEETH 191 
 
 to make for a greater degree of retention, but outline angles should be 
 rounded. 
 
 The natural outline of the tooth should always be restored to as 
 perfect a degree as the skill of the operator will permit. A tooth may 
 be restored with a filling that will be inharmonious in color, as with 
 gold, but if the form and size are correctly reproduced it will be much 
 more esthetic than if the color were to be perfectly restored while the 
 size and shape were to be distorted. In order to properly reproduce 
 the contour of a tooth it will frequently be necessary to separate the 
 teeth in order to obtain sufficient space to make a perfect form restor- 
 ation, for the reason that in the process of decay the teeth have fallen 
 together to such a degree that a large part of the mesio-distal dia- 
 meter of the tooth has been lost. If the loss is not great, sufficient 
 separation may be obtained by the use of the immediate separator 
 of the Perry or Ivory type; but if much of the mesio-distal diameter 
 has been lost it will be necessary to separate for some time in order 
 to obtain sufficient space. This may be accomplished in several ways : 
 
 (1) The operator may place an immediate separator upon the tooth, 
 and when as much separation has been obtained as is deemed wise, 
 gutta-percha may be packed into the cavity and left for several days, 
 the patient being instructed to call again, when the same process may 
 be repeated until a sufficient amount of space has been obtained to make 
 the proper restoration. (2) The cavity may be cleaned out and a 
 gutta-percha filling made, which will be a little more full than normal, 
 so that the patient will bite upon the filling. After wearing this for a 
 week a larger amount of the material may be placed in the cavity and 
 this repeated as often as necessary until the required space is secured. 
 This last method is the least painful and the best. 
 
 The resistance form is that form given to a cavity which will 
 enable the filling placed therein to withstand the stress that falls 
 upon it in mastication. When it is remembered that a filling will 
 have to stand the masticatory stress of from 100 to 300 pounds at each 
 closure of the jaw in the act of chewing the food, some idea is obtamed 
 of the necessity of studying closely the best form to give the cavity, so 
 that a filling placed in it will be able to bear this tremendous strain. 
 The best foundation known is the flat base, and the best form that can 
 be given a cavity is a flat base with parallel walls. A box with flat 
 seats and walls at a right angle would be the ideal cavity, and as nearly 
 as possible this should be the cavity that the student should strive 
 to obtain. In cavities occurring in the proximo-occlusal surfaces of 
 molars and bicuspids the double step is used, one in the occlusal surface, 
 called the occlusal step, and one in the gingival portion of the proximate 
 surface, called the gingival step. These fillings have to bear the 
 
192 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 greatest amount of stress, and this preparation best confers the abihty 
 to withstand the force brought to bear upon them. 
 
 The retention form is that form given to a cavity which pre- 
 vents the displacement of the filHng from any cause and consists very 
 largely of the same methods used in the resistance form, that is, the 
 flat seats and parallel walls. If the gold or filling material is thoroughly 
 condensed no other preparation is necessary, for the force of condensa- 
 tion will displace the elastic dentin slightly and the resultant spring of 
 the dentin will cause it to so hug the filling material that it will be 
 impossible to dislodge it. However, it is permissible to shape the 
 cavity so that it will be self -retentive; that is, the internal portion 
 thereof will be larger than the orifice, making a dovetail arrangement 
 of the whole cavity, which will prevent the displacement of the filling 
 short of breaking the tooth. This dovetailing should be very slight, 
 for it is not necessary to make much retention, and more than is neces- 
 sary is obtained at the sacrifice of useful dentin and the consequent 
 weakening of the tooth. 
 
 The convenience form is that form which we give a cavity which will 
 enable the operator to fill it more conveniently. After all, the filling 
 of the cavity is of the greatest importance, for no matter how perfectly 
 it has been prepared, if the filling material is not inserted so that it 
 hermetically seals the cavity the operation will be a failure. For this 
 reason it is of the greatest importance to make the cavity of such shape 
 that the operator can fill it perfectly. It is not possible to lay down any 
 hard and fast law on this subject, for here more than any other place 
 the personal equation of the operator comes into play. One operator 
 will be able to fill perfectly a cavity that will be impossible to another; 
 therefore the only rule that can be made is that every cavity should be 
 shaped so that the operator can fill it perfectly. One rule that is 
 universally true is that in the making of a gold-foil filling all portions of 
 the cavity should be so accessible that the plugger point can perfectly 
 reach them, for gold cannot be condensed around a corner. 
 
 Pits and pothooks are no longer permissible, for they are not only 
 useless as a means of retention but are positively harmful. A con- 
 venience pit may be used as a help in starting the gold, but not as a 
 means of retention. This sort of a pit should not be deep, only deep 
 enough to enable the operator to start his pellet of gold and have it 
 retained until he is able to fill that portion of the cavity and have the 
 general retentive form hold the gold firmly from that on. Many 
 operators do not use a convenience pit at all, simply depending upon the 
 point in one of the gingival angles for a starting place. 
 
 The removal of any remaining carious dentin should always be in- 
 sisted upon. Usually when the preparation of the cavity has pro- 
 
CAVITY PREPARATION AND THE FILLING OF TEETH 193 
 
 gressed thus far all of the infected dentin has been cut out, but in deep- 
 seated cavities there may be some decayed dentin left, and this should 
 be carefully sought out and removed, for any carious dentin is a menace 
 to the filling and a greater one to the life of the pulp. This should be 
 removed with a spoon excavator of as large a dimension as the size of 
 the cavity will permit. 
 
 The preparation of the enamel walls contemplates the beveling and 
 smoothing of the enamel margins. It may be remembered that the 
 outline form was obtained as the first part of the cavity preparation, 
 but the beveling and smoothing of the enamel margins was left as the 
 last part of the operation, for in the progress of the work the enamel 
 margins might be injured and roughened; therefore, the final finishing 
 of this important portion of the cavity is left until the last. The enamel 
 margins should be beveled all around the cavity for the protection of 
 the enamel margins themselves. In the study of the structure of the 
 enamel it will be remembered that it is composed of rods standing upon 
 end, resting upon the dentin, and in their general arrangement agreeing 
 to the form of the dentin. In studying the splendid reproduction of 
 Dr. Frederick B. Noyes' diagram upon the subject it will be noticed 
 that while there is a general agreement of the enamel rods in their 
 direction to that of the dentin, in some very important places there is a 
 discrepancy in their following the form of the dentin. 
 
 At the extreme gingival portion the enamel rods have a root-wise 
 inclination, and as they approach the middle third of the tooth they 
 straighten up, so that at that portion of the tooth they are practically 
 perpendicular to the dentin. As they approach the cusp of the tooth 
 the rods incline in the opposite direction, until at the apex of the 
 dentin cusp they are again perpendicular to the dentin. Passing 
 over the cusps they are found inclining toward the sulcus or fissure, if 
 there is one, and in the immediate vicinity of the fissure they join their 
 fellows on the opposite side in falling together to such an extent that 
 a cut through this territory will find no short rods upon the surface. 
 A study of this diagram will do more to teach the student the wisdom 
 and necessity of beveling the enamel walls than anything known. By 
 studying this it will be seen that a margin made in the gingival region, 
 if cut straight across the horizontal axis of the tooth, would leave a 
 large number of short enamel rods; that is, rods that were so cut that 
 the dentin portion did not rest upon the dentin. They were cut off 
 from their dentin base, and, as a consequence, are in a very weak con- 
 dition, so that the slightest stress will cause them to fall out and leave 
 a vulnerable spot in the filling. All modern operators are convinced 
 that more failures are due to this fault in cavity preparations than any 
 other, with the exception of a failure to carry out the lines of extension. 
 13 
 
194 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 Fig. 123. — Diagram of enamel rod directions, from a photograph'of a bucco-lingual 
 section of an upper bicuspid. (Noyes.) 
 
 Fig. 124. — -Diagram of enamel rod directions, drawn from a mesio-distal section of a 
 
 bicuspud. (Noyes.) 
 
CAVITY PREPARATION AND THE FILLING OF TEETH 195 
 
 On the contrary, when a pit or fissure is approached it will be found 
 that their arrangement is of such a nature that, as they are inclined 
 toward each other and into the cavity, a straight cut through them will 
 leave no short rods upon the surface. In the immediate vicinity of a 
 pit or fissure, therefore, it is not absolutely necessary to bevel the mar- 
 gin, and we do so only to be sure that we have removed any rods that 
 have been injured in the operative procedures. At all developmental 
 lines the rods are weak, and it is always a rule in the management of 
 the enamel margin, when a developmental line is approached, to go 
 beyond it and lay the margin in the strong enamel beyond the line of 
 fusion. 
 
 It will be noticed that as the enamel rods approach the cusps of any 
 of the teeth they incline toward the cusp. This will necessitate 
 making a very decided bevel as the cusp is approached, until arriving at 
 the crest of the cusps it is the part of wisdom to go beyond and cut off 
 the enamel and reproduce it in gold. A failure to do so will endanger 
 the filling by causing a breaking down of the enamel rods with an ulti- 
 mate destruction of the entire filling. 
 
 The beveling of the enamel margins, or the making of the cavo-sur- 
 face angle, as it is technically called, should be done with sharp chisels 
 and marginal trimmers. The occlusal and proximate portions may 
 be made with a chisel, but the gingival margins will be best obtained 
 with the marginal trimmers. Some operators prefer to make the re- 
 quired enamel bevel with sand-paper disks and strips, but this is an 
 error in technic, for the reason that a definite bevel cannot be as readily 
 obtained in this way, and for the further reason that the gold can- 
 not be adapted as easily to a polished surface as to a planed one. 
 Furthermore, the chisel in the hands of an observant operator is the best 
 indicator of the direction of the enamel rods. While in the main the 
 diagram of Dr. Noyes is correct, yet there are so many exceptions to 
 the rule that the operator is never sure of the lay of the rods in any 
 position on the surface of the tooth, except as it has been tested by the 
 cleavage under the chisel. Therefore the chisel in his hands becomes 
 the best possible guide as to where and how the enamel bevel should be 
 made in any particular case. 
 
 The toilet of the cavity comprehends the thorough cleansing of the 
 cavity of all chips and debris. As all of the operation has been con- 
 ducted under the rubber dam the tooth is in the best possible condition 
 for the reception of the gold, without any further treatment. If the 
 chip blower does not remove all of the cavity debris a piece of cotton 
 or spunk in the pliers will be all that is necessary. The freshly cut 
 dentin is in the best condition against which to pack the gold, so no 
 medicament of any description should be placed therein. If any 
 
196 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 moisture has penetrated to the tooth it should be dried thoroughly and 
 the dentin freshened by slightly cutting the surface with a sharp hoe. 
 
 There are five classes of cavities which are named according to the 
 tooth and their position on the surface thereof: 
 
 Class I. Cavities having their beginning in the defects of tooth 
 structure, as fissure and pit cavities. 
 
 Buccal Wall 
 
 Distal Wall 
 
 Mesial Wall 
 
 Lingual Wall Pulpal Wall 
 
 Fig. 125. — Occlusal cavity in the lower first molar, illustrating Class I cavities and 
 
 names of their walls. 
 
 Pulpal Wall 
 
 Buccal Wall 
 
 Lingual iVall 
 
 Gingival Wall Axial Wall 
 
 Fig. 126. — Mesio-occlusal cavity in the upper first molar, illustrating Class II cavities 
 
 and names of their walls. 
 
 Class II. Cavities having their beginning in the proximate surfaces 
 of bicuspids and molars. 
 
 Class III. Cavities having their beginning in the proximate surfaces 
 of incisors and cuspids not involving the angle. 
 
 Class IV. Cavities having their beginning in the proximate surfaces 
 of incisors and cuspids involving the angle, 
 
CAVITY PREPARATION AND THE FILLING OF TEETH 197 
 
 Class ^^ Cavities having their beginning in the gingival surfaces of 
 any of the teeth. 
 
 Labial Wall 
 
 Gingival Wall 
 Axial Wall 
 Lingvxil Wall 
 
 Fig. 127. — Mesial cavity in the upper central incisor, illustrating Class III cavities and 
 
 names of their walls. 
 
 GingivalWall 
 
 Axial Wall 
 
 Labial Wall 
 
 Lingual Wall 
 Distal Wall 
 
 Pulpal Wall 
 
 Fig. 128. — Mesio-incisal cavity in the upper central incisor, illustrating Class IV cavities 
 
 and names of their walls. 
 
 Gingival Wall 
 
 Mesial Wall 
 
 Distal Wall 
 
 Axial Wall 
 
 Incisal Wall 
 
 Fig. 129. — Labial cavity in the upper central incisor, illustrating Class V cavities and 
 
 names of their walls. 
 
 In the preliminary considerations we presented a plan of operation 
 that should be carried out in the preparation of any cavity, and in 
 
198 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 following the system it is advisable to adopt the sequence there given, 
 though it is possible to combine some of them in actual operation; for 
 instance, the resistance and retentive forms are so nearly alike in prac- 
 tice that it is nearly always possible to make them at the same time. 
 After one has been accustomed to this system of operation it will become 
 involuntary and will be followed without conscious thought or effort. 
 ' It is at this condition that the student should try to arrive, for the best 
 work is that which has been done so many times that the eyes and hands 
 have been so trained that they coordinate every step of the operation 
 without conscious effort, just as the organist plays the most difficult 
 compositions without giving thought to the technic, but devotes his 
 entire attention to the interpretation of the composer's thought, the 
 hands and feet involuntarily carrying out the designs of the composer. 
 Thus the dental operator, by repeatedly following the system here 
 given, finally arrives at the point where the system and its rules and 
 sequences are followed involuntarily, while the whole effort of the 
 operator is given to idealizing his work. 
 
 By reason of the failure of nature to close the enamel plates by fusion 
 with one another there will be a pit or fissure left at the point of failure 
 which will make an ideal place for the organisms of decay to penetrate 
 and begin the work of tooth destruction. Such places are the fissures 
 in the occlusal surfaces of bicuspids and molars, the pits in the buccal 
 surfaces of the lower and lingual surfaces of upper molars and in the 
 lingual surfaces of the upper incisors, particularly the laterals. 
 
 Class I Cavities. — If the carious process is just beginning there will be 
 only a fissure with very little decay, and that at a slight depth. This 
 is the ideal time to fill the tooth and prevent further destruction of 
 tissue, or any possible pulp complications by the incursion of the 
 pathogenic organisms, thereby causing irritation which might possibly 
 lead to inflammation and death. 
 
 Since the decay is very slight it will be necessary to open up the cavity 
 with an engine instrument. A cross-cut fissure bur No. 702 is the best 
 instrument with which to do this the most rapidly and efficaciously. The 
 bur should be placed in the point of entrance of the decay, and, when it 
 has penetrated through the enamel, rapidly follow the fissures to their 
 entire extent. With chisel No. 28 or No. 29 and mallet the enamel 
 may now be broken down to some extent, when, with an inverted cone 
 No. 37 or No. 39 the enamel may be undermined by cutting the dentin 
 from underneath the same. At the same time the depth of the cavity 
 may be obtained and the floor somewhat flattened. In this way the 
 required outline form is secured and at the same time some progress is 
 made in obtaining the resistance and retentive forms. When the 
 enamel has been undermined sufficiently for the chisel to break it the 
 
CLASS I CAVITIES 199 
 
 chisel should again be used and the entire outline form obtained. This 
 will mean that all of the fissures are eliminated and the margins of the 
 cavity are laid in smooth sound tissue. 
 
 In a cavity of this class there will be very little need of a resistance 
 form, for the force of masticatory stress will have a tendency to pound 
 the filling into the cavity, so the resistance and the retentive forms will 
 be identical. This form will consist of a flat pulpal wall, with the 
 lateral walls perpendicular to it, making the whole cavity as nearly 
 like a box as possible. The depth of the cavity will depend upon the 
 force of mastication, for a heavy masticatory stress would cause the 
 gold in a shallow cavity to flow and the filling would fail as a result. 
 The cavity should always penetrate the enamel and have the seat made 
 in dentin. It is rarely possible to make a filling that will stand the 
 stress of years of mastication with a depth of less than 1| mm., and it 
 would be as rare to have one deeper than 2| mm. If the penetration 
 of decay calls for a greater depth than that, it will be wise to fill the 
 cavity with a cement first, allowing the patient to wear this filling for a 
 week or more, and then, if all is well, make the cavity of the proper 
 depth, with the cement as a base. If there is only one point of deep 
 penetration, which is often the case, make the depth of the cavity 
 without considering the depth of penetration of this one point : do not 
 attempt to cut the floor of the cavity to the depth of the deepest part. 
 Make the rest of the floor flat at the required depth and then, when 
 finished, remove the decay from the part of deepest penetration and 
 proceed to fill in this way. 
 
 Fig. 130. — Occlusal cavity in the lower first molar. 
 
 In a cavity in this situation the convenience form is negligible, for 
 all parts of the cavity are accessible. However, if the filling is to be of 
 cohesive gold, do not make an undercut or even a perfectly perpendicu- 
 lar wall on the mesial, for to do so would make the adaptation of gold 
 at this point rather difficult (Fig. 130). 
 
 Slightly incline this wall mesially so that the plugger may reach the 
 
200 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 bottom of the cavity and perfectly adapt the gold to the walls. The 
 slight loss of retention, because of this preparation, will be more than 
 compensated by the ease of access and perfection of condensation of the 
 gold. If the filling is to be one of non-cohesive gold this convenience 
 form should be discarded and a sharp, square angle made at the mesial 
 portion of the cavity, for it will not be hard to adapt the non-cohesive 
 gold to an angle even though the line of force is not perfectly obtain- 
 able. The paralleling of the walls of the cavity can best be made by 
 the use of a fissure bur in the contra-angle hand-piece and the angles 
 made sharp with a hatchet. 
 
 All of the remaining carious dentin should now be removed. There 
 will usually be none left except in those cases in which there is a deeper 
 penetration of decay than it is thought advisable to make the cavity, 
 in which case, remove the remaining carious dentin until sound tissue 
 is found. The decay can best be removed with a spoon excavator of as 
 large size as the cavity will permit. The instrument should be placed 
 under the decay and the whole mass lifted out of the cavity. When all 
 of the decay has been removed it is well to thoroughly plane the under- 
 lying dentin to remove any infection and provide good, healthy tissue 
 against which to condense the gold. 
 
 The finishing of the enamel margins is the last act in the preparation 
 of the cavity and consists of smoothing all the lines of the cavity margin 
 and obtaining the cavo-surface angle. This should be made with a very 
 sharp chisel, carefully ascertaining the direction of the enamel rods and 
 then making a bevel about one-quarter of the thickness of the enamel 
 all around the cavity. It is best to make the cavo-surface angle with a 
 planing instrument rather than a stone or disk, because it has been 
 demonstrated that gold can be more easily adapted to a planed surface 
 than to a polished one. 
 
 The toilet of the cavity is made by the removal of any chips or debris 
 of any kind that may be left as a result of the preparation of the cavity. 
 The debris may usually be removed with a blast of warm air, but if not 
 the cavity should be wiped out with a piece of cotton or spunk. No 
 liquid of any sort should be used in the cavity, and if it becomes moist 
 through the leaking of the saliva through the rubber dam, or from any 
 other cause the cavity should be thoroughly dried and the dentin 
 freshened by going over it with a chisel or hoe. In case of close proxim- 
 ity to the pulp and the danger of thermal shock some non-conducting 
 substance may be placed between the gold and dentin. Dr. Black 
 advises a piece of quill, and this is very good. A good substitute may 
 be made of a piece of thin celluloid, cut so that it accurately fits the 
 bottom of the cavity. Or a little cavitin may be placed in the cavity, 
 care being used that none of it comes in contact with the walls or 
 
CLASS I CAVITIES 
 
 201 
 
 margins thereof. On the evaporation of the menstruum a thin layer of 
 celluloid will be adherent to the dentin and will make a very good 
 non-conductor of thermal changes. 
 
 Cavities occurring in the pits of upper molars are also Class I cavities 
 and are treated in the same manner as those in the occlusal surfaces of 
 the lower molars. The floors of the cavity are made flat, the walls 
 perpendicular to the floors and parallel to each other as much as the 
 nature of the case will admit and the enamel margins beveled all around 
 
 Fig. 131 
 
 Fig. 132 Fig. 133 
 
 Figs. 131, 132 and 133. — -Occlusal cavities in the upper first molar. Fig. 131 show- 
 ing cavities in central pit and distal fissure filled separately. Fig. 132 showing trans- 
 verse ridge cut across and pit and fissure cavities made as one. Fig. 133, same as Fig. 
 132, but disto- lingual fissure involved. 
 
 the cavity. If the oblique ridge has not been undermined and the 
 cavities are confined to the pits in the occlusal surface of the upper 
 molar it will not be wise to cut across the ridge and make the cavity as 
 one, but allow the ridge to remain intact, prepare a cavity in each 
 pit and treat them separately. In case the decay has progressed to 
 such an extent that the oblique ridge has been appreciably undermined, 
 it will be well to cut through the ridge, unite the cavities having their 
 beginnings in the central and distal pits and make them as one. In 
 this case the treatment will be practically identical with that of a cavity 
 
202 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 in the occlusal surface of the lower molar, except for such slight changes 
 as the anatomic form of the tooth will demand. If the lingual 
 marginal ridge remains intact the lingual margin of the cavity may be 
 established just before reaching the crest of the marginal ridge. But 
 if, as frequently happens the disto-lingual fissure is defective through- 
 out its length it is necessary to carry the cavity over the marginal 
 ridge onto the lingual surface of the tooth. Then the fissure should be 
 cut out the entire length until the margin will be laid in the smooth 
 territory to the gingival of the fissure. The fissure should be followed 
 with a No. 702 cross-cut fissure bur and the enamel broken down to the 
 outline form with a chisel. The gingival wall should be made flat with 
 a No. 35 or No. 37 inverted cone bur followed by the use of an obtuse 
 angle hoe of proper size to fit the situation. The mesial and distal 
 walls may be paralleled by the use of the inverted cone or the fissure 
 bur. A fissure bur is preferable in this situation. The making of the 
 cavo-surface angle offers but one point of emphasis, and that is the 
 lingual marginal ridge. The cavity as it p&,sses over this marginal ridge 
 finds the enamel rods bent toward the fissure and consequently in a 
 favorable condition to withstand the force of masticatory stress, for no 
 short rods are likely to be left upon the surface as a result of the prepara- 
 tion of the cavo-surface angle even though a straight cut were made 
 through the fissure. Owing to the unusual stress that will inevitably 
 come upon this portion of the filling it will be well to make a rather long 
 bevel so that the margins may be strengthened and at the same time the 
 filling so made that it will be able to withstand the stress of occlusal 
 force without flowing. Convenience angles may be made in the disto- 
 axial and mesio-axial angles, but the one in the mesio-axial angle should 
 not be very pronounced, for if it were it would be difficult to reach it 
 with the point of the plugger and an imperfect condensation of the gold 
 at that point would result. In preparing a cavity for the reception of 
 a gold filling it should be in the operator's mind never to prepare any 
 angle or position of the cavity in such a way that it will not be perfectly 
 accessible to the plugger, for gold cannot be well condensed around a 
 corner. The attempt to seal hermetically a place in a cavity that is 
 inaccessible to the plugger point will invite infiltration decay by 
 reason of a failure to perfectly adapt the filling material to the dentin 
 at that point. 
 
 Cavities occurring in the pits and fissures of the bicuspids, both upper 
 and lower, are Class I cavities, and their treatment calls for no further 
 amplification. The seats should be made flat and only as deep as the 
 carious condition will demand, for here there will be no unusual stress 
 and the carrying of the depth of the cavity through the enamel will be 
 sufficient to maintain the integrity of the filling. In case there is a 
 
CLASS f^C AVI TIES 203 
 
 deeper penetration of the decay it will be necessary to make the cavity 
 deeper, of course, but the resistance and retentive forms are amply 
 provided for if the filling is well anchored in the dentin. 
 
 Cavities in the buccal surfaces of the lower molars and lingual sur- 
 faces of the upper incisors are pit cavities and therefore in Class I. 
 Their preparation will be with the flat seat, parallel walls and the bevel- 
 
 a h c d 
 
 Fig. 134. — Occlusal cavities in the bicuspids, a, lower first bicuspid; b, lower second 
 bicuspid; c, upper second bicuspid; d, upper first bicuspid. 
 
 ing of the cavo-surface angle. No special mention need be made of the 
 preparation of these cavities, except to warn the student against the 
 exposure of the pulp in the case of the cavities in the lingual surfaces 
 of the upper incisors. If a very deep preparation should be attempted 
 there would be a great danger of pulp complications. These cavities 
 should be sought out at the very first opportunity and filled before there 
 
 Fig. 135. — Buccal cavity in the lower first Fig. 136. — Lingual cavity in the 
 
 molar. upper lateral incisor. 
 
 is any great penetration of decay. The depth of the cavity need not 
 be great for there will be little stress in this situation and a deep resist- 
 ance form is not necessary. The convenience angles should be made 
 in the disto and mesio-gingivo-axial angles for a point in the inciso- 
 axial angle would be so out of the line of force that it would be difficult 
 to fill perfectly. Therefore, the retention should be made by the box- 
 
204 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 like form of the cavity assisted by the angles in the gingival portions 
 of the cavity, making the angle in the incisal portion as acute as possible 
 to reach with the plugger point, but no more. Fortunately, no great 
 degree of stress falls upon a filling made in this situation so that a great 
 deal of retention is not necessary, and a perfect adaptation of the gold 
 to the cavity is of more importance than the resistance or retentive 
 forms. 
 
 There are a number of weak spots in the enamel in this surface, 
 being at the developmental lines, and care should be taken to seek them 
 out, remove any frail portions, and so bevel the margins that the 
 enamel will be perfectly protected. 
 
 Fig. 137. — Mesio-occlusal cavity in 
 lower first mola,r. 
 
 Fig. 138. 
 
 -Mesio-occlusal cavity in lower 
 second molar. 
 
 Class II Cavities. — Class II cavities are those having their beginnings 
 in the proximate surfaces of bicuspids and molars. The decay has its 
 inception on the proximate surface of the tooth just gingivally to the 
 contact point, and is not apparent to the patient until it has made con- 
 siderable progress; perhaps not until the carious process has gone so 
 far that a sudden force upon the occlusal portion of the tooth in mastica- 
 tion breaks the marginal ridge and the cavity is opened up, when the 
 patient presents with the statement that the cavity came all at once. 
 It is sometimes difficult for the dentist to find these cavities in their 
 inception, and yet that is the time they should be located and filled; 
 therefore, it is the duty of the dentist to make a careful search for this 
 class of, cavities, using small curved explorers for the purpose, being 
 assisted by the use of the electric mouth lamp and compressed air. 
 The lamp will frequently assist in locating cavities that defy the 
 ordinary methods of search, and the compressed air is valuable in 
 clearing away the saliva and debris and giving a clear field for inspec- 
 tion. 
 
 When a cavity of this class is to be filled it is the invariable practice 
 to fill it from the occlusal surface, making it a proximo-occlusal cavity. 
 
CLASS II CAVITIES 205 
 
 This is for the double purpose of making the extension and resistance 
 forms more perfect and making the cavity of such convenient form that 
 the gold can be well adapted to the walls of the same. Fillings made by 
 the old method of attempting to fill the cavity by making a simple 
 proximate cavity failed, because there was a recurrence of decay around 
 the margins that were not brought out into immune territory. The 
 cavities so made were very difficult of access and the gold was imper- 
 fectly adapted to the walls thereof, so that the fillings leaked and there 
 was a recurrence of decay by infiltration. 
 
 Frequently cavities occurring in the proximate surface of a bicuspid 
 or molar are complicated by the presence of decay starting in a fissure 
 in the occlusal surface. Whether that be true or not the entrance to 
 the cavity is through the occlusal surface. By the use of a cross-cut 
 or dentate fissure bur No. 702 an entrance is made through the enamel 
 into the dentin and the bur is made to travel toward the margin cutting 
 
 Fig. 139. — Two views of mesio-occlusal cavity in Fig. 140. — Mesio-occlusal cavity 
 
 upper first bicuspid. in the lower first bicuspid. 
 
 into the dentin and drawing it up through the enamel. In this way the 
 enamel is undermined and its organization broken up to such a degree 
 that the breaking down of the same is a very easy matter. If the decay 
 has penetrated into the dentin from the proximate surface to any great 
 extent it will be a very short time until the bur will fall into the cavity, 
 when the marginal ridge should be undermined with the bur cutting 
 upward at the same time, making a sweeping motion sideways to widen 
 the cavity. When sufficiently undermined the marginal ridge should 
 be broken down by the use of chisel No. 38 or No. 39. With the same 
 bur the cavity may now be deepened toward the gingival by cutting 
 close to the dento-enamel junction and sweeping the bur from lingual 
 to buccal. Cut the cavitj^ until a sufficient gingival depth has been 
 obtained. The enamel, being undermined by this operation, can be 
 cut away easily with the chisel and the buccal and lingual extensions 
 obtained in the sajne way. The easiest and most expeditious niethod 
 
206 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 of removing the enamel is to place the edge of the chisel at the enamel 
 margin where the break is desired, and then tap the end of the chisel 
 with the mallet. If the enamel has been properly undermined it will 
 be very easy to break it away until the proper outline form has been 
 obtained. The occlusal step should be made by the use of the inverted 
 cone bur No. 37 or No. 39 as the width of the step may demand. The 
 outline form has been obtained by the breaking down of the enamel 
 under the chisel and mallet, so it will be comparatively easy to cut the 
 dentin to the proper depth and form. The depth will have to be 
 gauged by the amount of resistance that the filling will have to with- 
 stand, and will comprehend one of the points of the resistance form, 
 which we should now have in mind. If it has been ascertained that 
 there is a strong occlusal force that will probably be exerted upon the 
 finished filling, it will be necessary to make the cavity correspondingly 
 deep and broad. If it is to be a deep and broad preparation, a No. 39 
 inverted cone bur should be the choice and the floor of the occlusal step 
 made as deep as necessary. If the force to be withstood is moderately 
 great a depth of 1| mm. will usually be sufficient; but if the occlusion is 
 particularly strong, 2 mm., and in rare cases, 2J mm. will be permissible. 
 In making the resistance form in the occlusal step the lines of the 
 recession of the pulp should be in mind and care should be observed 
 not to cut through these lines for fear of cutting into a prolongation of 
 a horn of the pulp, in which case the destruction thereof would be an 
 inevitable consequence. It will not be possible to give a study of the 
 recessional lines of the pulp in this treatise, but the student is urged to 
 familiarize himself with the subject so that he may avoid the distressing 
 accidents that an ignorance thereof will inevitably lead him into, 
 namely, exposure of the pulp. 
 
 When the cavity depth has been obtained the walls should be made 
 perpendicular to the floor and should be as nearly parallel to each other 
 as the form of the tooth will permit. The ideal that should be always 
 before the operator is to make his cavities as nearly like a box as 
 possible and only depart from that as the anatomic form of the cavity 
 and the exigencies of the carious process may demand. Decay does 
 not follow any hard and fast lines, and while the ideal should always 
 be sought it must be borne in mind it may not always be attained. 
 However, with an ideal in mind and an effort for its attainment one 
 may become a more perfect operator. 
 
 The squaring out of the cavity, paralleling of the walls, etc., will be 
 most easily obtained by the use of the fissure bur, either plain or dentate. 
 After the walls and floor have been roughly squared out by the use of 
 the burs they should be smoothed by the use of the hoe No. 4 or No. 5 
 or the chisel No. 29 or No. 31. 
 
CLASS II CAVITIES 207 
 
 The gingival wall should be made flat by the use of the inverted cone 
 bur No. 37 or No. 39 as the case may be, the choice of the smaller or 
 larger bur being determined by the resistance form that has been 
 chosen. If the resistance is to be great the larger bur should be the 
 choice, but if the seat is not to be as broad as that contemplated by the 
 use of the larger bur then the No. 37 should be used. The idea that 
 is to be in the mind of the operator all the time is to make the cavity 
 of proper proportions and adequate strength. The buccal and lingual 
 walls are to be made perpendicular to the step and parallel. In 
 the linguo-gingivo-axial and bucco-gingivo-axial angles, convenience 
 points should be made for the retention of the first pieces of gold, 
 whether the cohesive or non-cohesive methods are contemplated. 
 These points are made by allowing the shank of the bur to follow close 
 to the bucco or linguo-axial lines and then letting the head of the bur 
 sink into the gingival point angle. The angle may be made sharper by 
 the use of the 33| inverted cone bur or the hand instrument No. 8 or 
 No. 9. These instruments are primarily intended for the beveling of 
 the cavo-surface angle, but are admirably adapted for the making of 
 point angles in the dentin. 
 
 The general outline of the resistance form and retention form being 
 made by the use of the bur, it is well to smooth up the cavity by the use 
 of the obtuse angle hoes, going all over the dentin with a planing 
 motion thus making a smooth and beautiful finish. 
 
 In making a proximo-occlusal cavity in a molar or bicuspid we have 
 obtained the required convenience form, for no angle of the cavity so 
 made is placed so that the plugger point cannot directly reach it and 
 the condensation of the gold against all of the walls of the cavity is 
 assured if the operator uses the right technic in condensing the same. 
 
 If there is any remaining carious dentin it must be removed, after 
 which the enamel margins should be finished. This means that all of 
 the marginal lines should be squared up. The lines from the occlusal 
 to the gingival margins should be made as straight as possible. Par- 
 ticular care should be given to the linguo and bucco-gingival outline 
 angles to see that they are well out of the embrasures. These are the 
 points of the greatest vulnerability and are the points of the most 
 frequent failure by reason of a recurrence of decay around the margins. 
 Because of the fact that the angles have been rounded off or allowed 
 to fall so far within the embrasures that the margin of the filling was 
 within the area of susceptibility, and the bacterial plaques were there- 
 fore enabled to fasten themselves upon the enamel in proximity to the 
 filling, a new point of decay was started that undermined the filling 
 and the destruction of the same was the outcome. To prevent such an 
 occurrence, square out the angles of the cavity to such an extent that 
 
208 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 they will be in immune territory and no fear need be felt of a failure by 
 reason of a recurrence of decay if the gold has been properly adapted. 
 
 The cavo-surface angle must now be made, and at the gingival margin 
 in an upper tooth can best be made with right and left instruments 
 designed for this purpose, Nos. 8, 9, 10 and 11. These margins on 
 the proximate surfaces of the lower molars and bicuspids are best 
 made with the Nos. 12 and 13 for margins on the distal surfaces and 
 Nos. 14 and 15 for margins upon the mesio-gingival surfaces. The 
 buccal and lingual margins can be made with the chisels Nos. 28, 29, 
 30 and 31. 
 
 The cavo-sm-face angle upon the occlusal surface is also made with the 
 chisel. All of the cavo-surface bevel for the gold filling is made at an 
 angle of from 10 to 15 centigrades and from one-fourth to one-half of 
 the thickness of the enamel. 
 
 Fig. 141. — Proximo-occlusal cavity 
 in upper molar, showing method of 
 protecting a weak cusp, by cutting off 
 a portion and restoring with gold (a) 
 mesio-buccal cusp cut off. 
 
 Fig. 142. — Mesio-occlu so-distal cavity in 
 bicuspids, showing method of strengthening 
 weak cusps. 
 
 The toilet of the cavity finishes the preparation and the rubber dam 
 having been in position and the excavation having been made in a dry 
 cavity, there is usually little that need be done. A blast of warm air 
 is usually sufficient, but if not, this may be supplemented by going over 
 the cavity with a piece of cotton or spunk in the pliers. 
 
 If the carious process has progressed so far that the cusps of the tooth 
 are undermined or weakened by the near approach of the decay, it will 
 be necessary to protect them by cutting off a portion of the cusps and 
 building the gold over them. If this is not done there will be danger 
 of breaking off one or more of the cusps. This is particularly true 
 in the case of a tooth from which the pulp has been removed. In 
 the event that it is thought advisable to protect them, grind off a portion 
 of the cusp or cusps as may be thought expedient. The amount of the 
 tooth to be removed must be deterjuined by the amount of decay that 
 
CLASS II CAVITIES 209 
 
 has undermined the cusp and the amount of stress that will be brought 
 to bear upon the finished filling. It should always be enough to make 
 room for a sufficient bulk of gold to stand the stress of mastication 
 without flowing. A sufficient amount of the enamel should be removed 
 to bring the cavity to sound tissue supported by a good body of dentin. 
 In the finishing of the cavo-surface angle in this class of cases the bevel 
 should be decided and of sufficient depth to make for a goodly flange of 
 gold that will go over the enamel margin and effectually bind the walls 
 together. If the cavity is so made and the amount of gold that over- 
 lays the walls of the tooth is sufficient, there mil be little danger of a 
 fracture of the tooth. This rule is one that should be followed in all 
 cases whether the cavity occurs in a bicuspid or a molar. It is also of 
 ec[ual importance to protect the incisal angles of incisors and cuspids in 
 case of a like weakness. 
 
 a be 
 
 Fig. 143. — Three views of mesio-occluso-distal cavity in upper first bicuspid, a, mesia 
 view; b, occlusal view; c, distal view. 
 
 Cavities involving the distal and mesial surfaces of the same tooth 
 are restored by the making of a mesio-disto-occlusal filling. In these 
 cases the method of procedure is the same as in the case of a cavity 
 occurring in either the mesio-occlusal or disto-occlusal siu*face of a tooth. 
 The outline form is made so that all of the lines of the cavity are in 
 relatively safe territory, while the resistance and retentive forms follow 
 the laws of flat seats and parallel walls. The only difterence in the 
 cavit}^ is that the cavities in the two surfaces of the tooth are treated as 
 one and filled at the same time. 
 
 There is no difference in the principles governing the preparation of 
 the cavity, whether the carious process occurs in a lower or an upper 
 tooth. There is a difference in technic due to the location of the tooth 
 in the mouth and the dissimilarity of approach. In the making of a 
 cavity in the lower molars and bicuspids it will be expedient to use the 
 14 
 
2l0 CAVITY PREPARATION AND THE EILLING OF TEETH 
 
 contra-angle hand piece. This will bring the bur into proper relation 
 to the tooth to make the advised preparation. The walls of the 
 cavity and the internal angles can best be cut by the use of enamel 
 hatchets Nos. 22, 23, 24 and 25, assisted in some instances by the 
 very useful angle chisels Nos. 32 and 33. 
 
 As indicated above, the cavo-surf ace angle of the gingival margin in 
 the lower teeth is made with the special marginal trimmers Nos. 12, 13, 
 14 and 15, Nos. 12 and 13 being for the angles on the disto-gingival 
 margins and Nos. 14 and 15 being adapted for the making of the angle 
 on the mesio-gingival margins. In all other respects the cavities are the 
 same and the technic identical except in the processes enumerated. 
 
 a h 
 
 Fig. 144. — Mesial cavity in upper central incisor, a, labial view; b, lingual view. 
 
 Class O Cavities.^ — Class III cavities are those occurring in the proxi- 
 mate surfaces of the incisors and cuspids not involving the angle. The 
 beginnings of the decay are to be found immediately gingivally to the 
 contact point and should be discovered at the earliest possible moment. 
 There is very little excuse for these cavities attaining any appreciable 
 size in the teeth of patients that present for regular examinations. 
 Indeed, there is little excuse for a cavity in any surface of the tooth 
 making much headway if the patient is conscientious in presenting for 
 examination at frequent intervals. But while there might be some 
 excuse for overlooking an incipient cavity in the proximate surface of 
 the second or third molars there is no excuse for the failure to discover 
 a cavity beginning in the proximate surface of an incisor or cuspid. 
 
 In the treatment of Class III cavities, the rubber dam being in place, 
 separation must be made, if it has not already been obtained. A 
 separator of the Perry or Ivory type should be carefully placed. Too 
 much pressure must not be used on the single rooted teeth for fear of 
 making the movement so great and sudden that permanent injury may 
 be done to the peridental membrane or pulp. The pressure should be 
 applied gradually and the separator tightened as the tooth moves in the 
 
CLASS III CAVITIES 211 
 
 arch. When sufficient separation has been obtained the point of decay 
 may be entered with a No. 2 round bur. The dentin should be under- 
 mined by cutting under the enamel, after which with chisel No. 30 
 the enamel wall may be broken down to the extent of the undermining 
 thereof. This undermining of the enamel with the bur and breaking 
 down with the chisel should be continued until the desired outline form 
 has been obtained. This form contemplates carrying all of the margins 
 of the filling out of the areas of susceptibility and will mean that the 
 labial margin will be carried labially far enough out of the embrasure 
 to prevent the enamel coming into contact with the enamel or filling 
 in the approximating tooth. In making this extension it is not neces- 
 sary to bring the gold into such open view that it makes a glaring defect. 
 The cutting of the labial portion of the tooth to such an extent that it 
 disfigures the patient is not good practice, and except in case of exten- 
 sive decay should not be tolerated. If sufficient separation has been 
 obtained, enough room to perfectly adapt the gold to the walls of the 
 cavity can be obtained without a disfiguring restoration. At the same 
 time the extension must always be sufficient to cause the gold to clear 
 contact with the approximating tooth or the margin will lie in unclean 
 and therefore susceptible territory. 
 
 The gingival margin should be cut far enough to allow the gum to 
 cover the margin of the finished filling. The incisal portion should be 
 cut far enough to make the contact on the gold and not on the enamel. 
 Lingually the margin should be carried out far enough to bring it clear 
 of the approximating tooth. This margin should be rather generously 
 cut for the reason that it is not within the range of vision, and the 
 further reason that it is a more difficult portion of the filling to make and 
 by more extensive cutting a greater convenience form is obtained. 
 
 The points of greatest vulnerability, and therefore the areas of the 
 greatest number of recurrences of decay, are the labio and linguo- 
 gingival angles. The reason that there is so great a proportion of 
 recurrences of decay in this territory is that in the preparation of the 
 cavities these angles have not been properly squared-out. It is 
 natural, in making a cavity in this surface, to prepare a rounded angle 
 at the labio and linguo-gingival angles which leaves these margins so 
 far within the embrasures that they are not kept clean. The student 
 should emphasize these angles to such an extent that they are seemingly 
 overprepared, for in the large majority of cases an angle that looks 
 to him as though it was too far out of the embrasure will, when filled, 
 be just about right, with the probabilities in favor of the fact that he 
 has not cut far enough. In the outline form of a cavity in the incisal 
 or mesial surface of the cuspid we look for the esthetic form more than 
 in any other class of cavities, for here more than any other place does 
 
212 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 the filling obtrude itself upon the consciousness of the observer. There- 
 fore the angles that are within the range of vision should be rounded. 
 In attempting to make rounded angles the student is led into the greater 
 error of not bringing them out far enough, and it will take much time 
 and patient observation to obtain the necessary perfect balance. The 
 angle should first be brought out sufficiently far for purposes of safety, 
 and when that is accomplished the squared angles should be gently 
 curved and made to take on the esthetic form of outline. This is not 
 necessary at the linguo-gingival angle but must be made a matter of 
 routine in making the labial angles both at the gingival and incisal. 
 
 The resistance form takes the form of the squared cavity. The 
 gingival wall should be made flat from the axial wall to the surface of 
 the enamel, but labio-lingually it may be curved to harmonize with the 
 outline of the cemento-enamel juncture. The round bur should be 
 discarded as soon as the outline form has been obtained and should 
 never be used in making the resistance or retentive forms. In the 
 class under discussion the best bur to use is the No. 35 or No. 37 
 inverted cone. 
 
 The end of the bur should be used in making the flat seat at the 
 gingival and the sides of the bur may be used in making the labial or 
 lingual walls. These walls should be as nearly at right angles with the 
 gingival seat as the form of the tooth will permit. The incisors being 
 of a wedge form a cavity in the proximate surface that attempts to 
 conform in some degree to the shape of the tooth will of necessity 
 take the form of a triangle. The walls of the cavity will therefore con- 
 verge as they approach the incisal angle and the finished cavity will be 
 triangular in shape. The axial wall should be made to conform to the 
 shape of the pulp; the labial and lingual portions of the same being 
 made deeper than the center, that the pulp may have all the protection 
 of dentin that is possible. The angles should be slightly accentuated, 
 and this may be accomplished with a 33| inverted cone bur and the 
 point angles then sharpened with the hand instruments Nos. 8 and 9. 
 In making the emphasized angles at the labio and linguo-gingivo- 
 axial angles, there is usually sufficient convenience point to start the 
 filling, but if not, it is permissible to make a convenience point for the 
 starting of the gold in either of the gingival angles. 
 
 The labial and lingual walls may be cut out with the right angle 
 hoes Nos. 6 and 7 . The point angle at the incisal may be best made 
 with the 33| inverted cone bur. In making the cavity of the shape 
 suggested we have satisfied both the retentive and resistance forms. 
 The convenience form is very important in this class of cavities, for if 
 the operator is not able to reach all parts of the cavity with the plugger 
 point he will be unable to perfectly adapt the gold to the walls of the 
 
CLASS IV CAVITIES 213 
 
 same, and in this situation some of the parts of the cavity may be very 
 inaccessible if the cavity is not sufficiently opened up. It is important, 
 then, at this stage of the operation to determine whether all parts 
 of the cavity are accessible to the plugger point, and if not, to cut 
 away enough of the outline to make the cavity convenient. 
 
 The enamel margins should be beveled all around the cavity. The 
 labial and lingual margins may be planed with a chisel and the bevel 
 at the incisal may be made with the same instrument. The gingival 
 cavo-surface angle should be made with the right and left instruments 
 Nos. 10 and 11. The toilet of the cavity is made by removing all 
 debris, carefully searching out any remaining carious dentin and the 
 cavity is ready to fill. 
 
 Class IV Cavities. — Cavities of the fourth class are those occurring 
 in the incisors and cuspids involving the angle. 
 
 a be 
 
 Fig. 145. — Mesio-incisal cavity in upper central incisor, a, labial view; b, mesio-distal 
 longitudinal section; c, lingual view. 
 
 This class of cavities is more difficult to fill by reason of the fact that 
 in the loss of the angle so much of the tooth has been destroyed that the 
 problem of retention is considerably intensified. There have been 
 several ways suggested for its solution, but the step cavity has been the 
 best in practice and will be adhered to in this treatise. The outline 
 form will be obtained by breaking down all overhanging enamel walls 
 and bringing the margins of the cavity into sound territory. The 
 problem of extension for prevention is usually solved by the progress 
 of the decay, for if the angle has been involved it is more than probable 
 that the tooth has decayed so far that the finished filling will have its 
 margins in safe territory. After the enamel walls have been trimmed 
 down the incisal portion of the tooth should be ground with a flat 
 carborundum stone, the depth and extent of this cutting to be governed 
 by the study of the conditions obtaining in the special case. If the 
 
214 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 occlusion is great there will be the necessity for a considerable trimming 
 of the incisal portion of the tooth in order to allow for a sufficient 
 amount of gold over the incisal angle to withstand the stress of occlusion 
 without flowing. It is obvious that the least cutting that can be done 
 with safety should be the ideal, for here, more than in any other place, 
 will the gold be within the range of vision. In order to obviate this 
 difficulty, operators have made the incisal step entirely to the lingual, 
 leaving the enamel at the labial surface practically intact; but the 
 fallacy of this preparation has been proved by the breaking down 
 of the unsupported enamel at the labial or the infiltration of the 
 filling by the flowing of the insufficient mass of gold over the incisal 
 portion of the filling. In this place we will have to sacrifice 
 esthetics for utility and make as deep and broad a preparation as the 
 case demands or failure will result. In case there is no occlusion 
 the hiding of the gold by making nearly all of the step to the lingual 
 is permissible, but if the opposing incisors are able to come into 
 contact with the incisal portion of the tooth in question it will be 
 imperative to cut away enough of the labial plate to allow for a sufficient 
 mass of gold to stand up under stress. The amount of the incisal edge 
 involved, mesio-distally, will also be determined by conditions. Usually 
 it will be necessary to cut past the opposite developmental groove, for 
 in making the incisal step it will nearly always be necessary to carry 
 it past the middle of the incisal portion of the tooth, and in doing so 
 will carry the margin so near the developmental groove that the margin 
 of the cavity will be in weak territory. In order to prevent this it will 
 be found advisable to carry the margin past the groove and finish it in 
 the strong enamel beyond. The labial portion of the step will, in 
 ordinary cases, be cut to a depth of 1mm. or 1| mm., while the lingual 
 portion will be made considerably deeper. The lingual portion is made 
 deeper for several reasons: (1) because it is out of the line of vision, 
 it may be cut as deep as desired without the violation of any esthetic 
 ideal, and (2) because in the stress of mastication the lower teeth strike 
 against the lingual surface of the upper, and, as a consequence, the 
 greater mass of gold is required at that point. The incisal third of 
 incisors and cuspids is almost entirely composed of enamel, due to the 
 convergence and union of the labial and lingual enamel plates. There- 
 fore, in order to provide sufficient width of dentin labio-lingually, to 
 properly prepare a step, it is necessary to sacrifice one or both plates of 
 enamel. Since the preservation of the labial plate is desirable for 
 esthetic reasons, the lingual plate is cut far enough to provide sufficient 
 dentin in which to anchor the filling. The outline form being completed, 
 the resistance and retentive forms should be made. The gingival wall 
 is made as flat as the nature of the case will allow. In incisors and 
 
CLASS IV CAVIfiSS 215 
 
 cuspids, as has been said, it is permissible to follow the cemento- 
 enamel curve, which will cause the filling to seat upon the convex side 
 of an arch, which in mechanics is unobjectionable, especially when 
 there is not the tremendous stress that will be brought to bear upon 
 a filling in a molar or bicuspid. On the other hand, if we insisted on 
 making the gingival seat flat in the incisors and cuspids we would often 
 find that we would run into the cementum and perhaps the peridental 
 membrane in the central portion of the cavity when we were trying to 
 bring the labio and linguo-gingival angles into safe territory, for there 
 is frequently so great a curve of the cemento-enamel line that it is carried 
 down into the embrasure so far that a flat seat for the filling that would 
 not endanger this line would tend to make a very shallow linguo and 
 labio-gingival angle. Therefore it is the part of wisdom to curve the 
 gingival wall labio-lingually in incisors and cuspids, so that it will in 
 some degree conform to the curve of the cemento-enamel line. 
 
 This step is best obtained by the use of inverted cone burs Nos. 35 
 and 37, according to the size of the tooth being operated upon. The 
 proximate walls will be made triangular with the base to the gingival 
 and the apex toward the incisal. These walls should be as nearly at 
 right angles to the gingival step as the form of the tooth will permit, 
 having them converge as they approach the incisal. At the inciso- 
 proximate angle the cavity will pass into the incisal portion in a groove 
 cut into the dentin between the labial and lingual enamel plates. This 
 groove should not be very deep and should not cut into the enamel. 
 It should be confined entirely to the dentin and some dentin should be 
 left on either side to protect the enamel. After passing the site of the 
 recessional line of the pulp a pit is sunk into the dentin for a slight 
 distance to help resistance to lateral displacement. The groove in the 
 incisal portion of the cavity should be made with a small inverted cone 
 bur, usually a No. 35 in an upper incisor or cuspid. The pit may be 
 made with the same instrument and rendered slightly retentive by 
 undercutting to some extent. The linguo and labio-gingivo-axial 
 point angles should be definitely emphasized, for upon them, to a great 
 extent, depends the retentive form of the cavity. These angles should 
 be made in the same way as those in the corresponding angles in Class II 
 cavities in bicuspids and molars. The angles are made with a No. 35 
 inverted cone bur and accentuated with the instruments Nos. 8 and 9. 
 If desired a convenience point may be made in the linguo-gingivo-axial 
 angle, but the making of the retentive angles is usually suflacient for the 
 purpose of starting the filling. The shape of the incisal step cavity is 
 such that no more convenience form is needed, so it will not be neces- 
 sary to elaborate upon that. Any remaining decay should be carefully 
 removed, the cavo-surface angle beveled all around the margins with 
 
216 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 the usual hand instruments, the toilet of the cavity made and the 
 cavity is ready for the filling. 
 
 Fig. 146. — Mesio-incisal cavity, upper 
 cuspid. 
 
 Fig. 147. — Disto-incisal cavitj-, upper 
 cuspid. 
 
 In proximate cavities occurring in the distal surfaces of cuspids it is 
 very difficult to perfectly adapt the gold to the walls of a cavity made. 
 
 d e f 
 
 Fig. 148. — Gingival cavities, a, upper cuspid; b, upper central; c, lower cuspid; 
 d, lower first molar; e, lower second molar; /, lower third molar. 
 
 as is usual in CUass II. Therefore, some of our best operators have 
 suggested making all such cavities into Class IV, intentionally involving 
 
CLASS V CAVITIES 217 
 
 the angle and making a step in the incisal surface. They do this for 
 the purpose of making the cavity of sufficient convenience that the gold 
 may be perfectly adapted to it, rightly believing that it is wise to cut 
 away sound tooth structure that the rest of the tooth may be saved 
 with a filling rather than attempt to save a portion of the remaining 
 healthy tooth structure, and by so doing lose the whole tooth by a 
 recurrence of decay, because a perfect filling was not made by reason 
 of the difficulty of adaptmg the gold to a surface that was not -within 
 the reach of the plugger point. 
 
 In making this cavity the same rules and technic are followed as 
 outlined for a step cavity in an incisor. 
 
 Class V Cavities. — Cavities occurring in the gingival third of any of 
 the teeth are Class A' cavities. The placing of the dam in this class is 
 sometimes very difficult. Especially is this true if the decay has pene- 
 trated very far beneath the surface of the gum, as is frequently the case 
 in advanced cases. In order to place the dam properly it will be neces- 
 sary to have a special clamp to push the gum back and to hold the rubber 
 in place. There are several good clamps on the market. If the decay has 
 not penetrated very far an ordmary gingival clamp of the Ivory tx'pe may 
 be used effectively. The Hatch and Woodward clamps are well adapt- 
 ed for cavities in which it is necessary to retract the gum in order to 
 gain access. The Ivory clamp is a very superior clamp for this purpose. 
 It is adjustable and is provided with a movable gum retractor that is 
 actuated by a screw with which the gum may be pushed back at will 
 as far as the operator desires. It is advisable to use an anesthetic 
 in cases where there is any considerable retraction of the gum for the 
 pain of the operation is intense. A local anesthetic used upon the 
 gum prior to the operation will obviate all this and make a very trying 
 operation, one that w]\\ be bearable. 
 
 When the dam has been placed and the field of operation cleansed, the 
 cavity may be opened with a spoon excavator and all of the decay 
 removed. In case it is a cavity in its incipiency it will be necessary to 
 open it up ^-ith a bur, when it is wise to use a No. 3 or Xo. 4 romid bur. 
 With this instrument excavate under the enamel imtil the walls may 
 be chiseled to the desired outline form. The axial wall of the ca^■ity 
 may now be flattened -^-ith an inverted cone bur of the proper size, 
 and ■s\'ith the same instrument the walls may be made parallel. The 
 general shape of the cavity should harmonize T^-ith the festoon of the 
 gum, ca^r^'ing the mesial and distal portions to the angles of the tooth. 
 The gingival margm should be placed well imder the free margm of the 
 gum, and the portion of the cavity looking toward the occlusal siu-face 
 of the tooth brought as far occlusally as will be necessary to obtain the 
 scouring action of the bokis as it passes over the teeth in mastication. 
 
218 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 As has been said, this will differ in teeth of varying shapes, the bell- 
 shaped tooth requiring a greater extension occlusally than a flat tooth 
 occluso-gingivally, for the reason that in the bell-shaped tooth the bell 
 will cause the bolus to leave the tooth a little beyond the middle third 
 and the gingival third will not receive any of the scouring action. It 
 will be wise to study the shape of the tooth in order to see how far occlus- 
 ally it will be necessary to carry the extension. In cases of any con- 
 siderable decay there will usually be a well-defined line of demarcation 
 showing where the frictional action of the food in mastication ceases. 
 Cut a little beyond this white line and the cavity will usually be in safe 
 territory. 
 
 The general shape of the cavity will be of a half-moon with blunt 
 edges, and the internal shape will be a flat seat and box-like walls. A 
 convenience point may be made in the disto-gingivo-axial angle for an 
 aid in starting the gold. The cavo-surface angle bevel should be made 
 all around the cavity, not so much for the protection of the enamel 
 rods, for in this class of cavities there will be very little stress upon 
 them, as to be sure that the enamel margins are sound and that there 
 are no loose rods lying upon the surface of the cavity. The toilet of 
 the cavity should now be made, assuring one's self at the same time 
 that all remaining decay has been removed. 
 
 FILLING TEETH WITH GOLD. 
 
 There are two kinds of gold used in filling cavities in teeth — gold foil 
 and the various makes of crystal gold. 
 
 The foil comes in the cohesive and non-cohesive forms and is used in 
 pellets, ribbons, cylinders and ropes. 
 
 The cohesive gold is pure gold with an uncontaminated surface. 
 Gold is a metal that does not oxidize when pure, and, consequently, 
 its portions being in the pure and uncontaminated state will cohere. 
 If any contamination adheres to the surface of the gold it becomes 
 non-cohesive; therefore, the operator heats it before using to drive 
 off any moisture or volatile substance that may have adhered to its 
 surface, or may have been placed upon it by the manufacturer. 
 
 There are two kinds of non-cohesive gold: that which is made tem- 
 porarily non-cohesive by the deposition upon its surface of some 
 volatile substance and the permanently non-cohesive gold, that is so 
 made by the deposition upon its surface of a substance that is not 
 driven off by heat, and, as a consequence, retains its non-cohesive 
 properties despite any heating that may be given it. We prefer 
 that which is made non-cohesive by the deposition of some volatile 
 substance for the reason that we may use the same gold for non- 
 
PILLING TEBlTH WITH GOLD 219 
 
 cohesive and cohesive filUngs as it suits our purpose, depending upon 
 whether or not we heat it. When this gold has not been heated it is 
 in the non-cohesive form, and when desired in the cohesive form it is 
 only necessary to heat it. 
 
 This form of non-cohesive foil is usually made by subjecting the gold 
 to the fumes of ammonia gas, which, being deposited upon the surface 
 of the gold, prevent the particles of gold from coming into perfect 
 contact and thereby prevent cohesion. 
 
 There are certain substances that, when condensed upon the surface 
 of gold, defy the power of heat to dispel them, and thus make the gold 
 permanently non-cohesive, a quality that is sometimes taken advantage 
 of by the manufacturers of the permanently non-cohesive types. Some 
 of these substances may be deposited upon the gold as it lies in the 
 cabinet or upon the operating tray. The fact that this does occur is 
 attested by the occasions when we find that it is impossible to make a 
 certain pellet of gold cohere to that placed upon the filling, or when we 
 find that the filling becomes flaky and the pellets fail to properly cohere. 
 That is the reason that an experienced operator uses nothing but freshly 
 prepared gold in his cohesive fillings, knowing from experience that if 
 he does not he will invite failure by having the gold fail to properly 
 weld. Therefore we advise the use of the non-cohesive or so-called 
 soft gold. The name soft gold is a misnomer, as all pure gold that is 
 annealed is soft. Gold becomes soft by annealing and hard by beating 
 or rolling; therefore, the cohesive gold is just as soft as the non-cohesive 
 when it is annealed. The reason that the non-cohesive gold is called 
 soft is because the old operators used the gold in the non-cohesive 
 forms, and when it became cohesive it was hard to use in the way in 
 which they were accustomed to use it. The non-cohesive form, by 
 reason of its non-cohesive qualities, worked more easily and seemed 
 soft under the instruments in contradiction to the harsh properties of 
 the cohesive gold sticking to the gold in the cavity and preventing the 
 newly placed gold from going easily to position. The names soft and 
 cohesive came from that source, but should now be discarded for the 
 better terms, heated and unheated or, if preferred, cohesive and non- 
 cohesive. We find, therefore, that we have two kinds of soft foil: 
 
 (1) non-cohesive foil, that which cannot be made cohesive by heating; 
 
 (2) non-cohesive foil, that which can be made cohesive by heating. 
 Both of these foils are called soft, but the first remains soft after heating, 
 while the second becomes cohesive or hard after heating. For this 
 reason we divide the non-cohesive foils into two divisions as follows: 
 unheated — soft foil — non-cohesive, and heated — soft foil — cohesive. 
 
 The non-cohesive is advised, because it has its surface protected by a 
 film of volatile gas — usually ammonia — which prevents the deposition 
 
220 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 upon its surface of any contaminating substance that would make it 
 permanently non-cohesive and would make a fault in the filling of which 
 it became a part. The ammonia remains upon the gold until it is 
 ready for the filling, when, upon being heated, it is driven off and a 
 perfectly pure fresh surface of the gold is presented for cohesion with 
 that in the cavity and that which is to follow it in the filling, making 
 for perfect cohesion and the possibility of a dense filling. 
 
 In preparing the pellets for use in making a cohesive filling we use the 
 No. 4 non-cohesive or soft foil. This comes in books of foil. The 
 pellets are prepared in eighths, sixteenths, thirty-seconds and sixty- 
 fourths. By this we mean that a sheet of gold is taken and divided 
 into eight parts and rolled into pellets, each pellet containing an eighth 
 of a sheet of gold. Likewise a sixteenth pellet is one containing 
 one-sixteenth of a sheet of gold, a thirty-second is a pellet contain- 
 ing one-thirty-second of a sheet of gold, etc. This is done in order 
 that we may definitely know the amount of gold under our plugger 
 point at any particular time. Definite methods produce definite results, 
 therefore we choose to know the amount of gold that we are using at 
 any given time, so that we may know the amount of force that will be 
 required to condense the gold to a required specific gravity. If we did 
 not know the amount of gold we were condensing we would not be sure 
 of the method we were using and could not be sure that we were produc- 
 ing the desired result. 
 
 The various forms of crystal gold in the market are cohesive and 
 have no particular advantage over the foil. In the opinion of the 
 authors they are not so good, but excellent fillings may be made with 
 them if the same care is taken in condensing as that given to the foils. 
 The reason that so many failures of condensation and pitted fillings are 
 made with the crystal foil is not the fault of the gold primarily but of 
 manipulation. It requires as much force to condense the crystal golds 
 as it does the foils; indeed, in Dr. Black's laboratory it was found that 
 it really required more force to obtain the same specific gravity with a 
 crystal gold than it did with a foil. If, however, the operator is not 
 misled by the belief that a perfect filling can be made without the 
 expenditure of much condensing force, and uses the same mallet pres- 
 sure upon a filling made with crystal gold that he uses in making a 
 foil filling, he will be able to make a good filling. 
 
 The foil, for use as a non-cohesive gold, must have an entirely dif- 
 ferent treatment, for here we will have to depend upon the mechanical 
 retention of the gold without any assistance of the coherence of the gold 
 itself. In making a non-cohesive filling, in whole or in part, this fact 
 must be ever in mind, that we must not depend upon the coherence of 
 the gold to help in the retention of the filling. 
 
FILLING TEETH WITH GOLD 221 
 
 Non-cohesive foil is used in cylinders, ribbons and ropes, but in this 
 treatise only the cylinders will be considered, because the other forms 
 are unnecessary and will only confuse the student if elaborated upon. 
 
 The cylinders are used in whole sheets, half sheets, quarter sheets and 
 eighth sheets. They are made by taking a sheet of non-cohesive 
 gold and dividing it into the number of parts required for the size of 
 cylinder wanted. If it is to be a half sheet cylinder the sheet of gold is 
 divided into two parts. One-half of the sheet is taken and made into 
 a ribbon by folding the gold upon itself a sufficient number of times 
 to make a ribbon of the width we want the length of the finished 
 cylinder to be. In our operations we will want a number of different 
 length cylinders according to the depth of the cavity upon which we are 
 operating. Knowing the length of the cylinder we will want, the ribbon 
 will be made to conform to that width. The ribbon of gold is now taken 
 and rolled upon the end of a Swiss broach or long pin of some kind. 
 A Swiss broach is more useful because the instrument is not round but 
 triangular in shape and the gold will roll better upon it because the 
 angles of the broach will engage with the gold and hold it from slipping 
 while the rolling process is going on. If a smooth instrument be used 
 the gold will have a tendency to slip and it will be difficult to make a 
 cylinder. The cylinder should not be too tightly rolled, nor so loosely 
 rolled that it will not maintain itself as a cylinder and unroll. The 
 ends of the cylinder should be smoothed by holding the cylinder in the 
 hands and slightly pressing in the ends between pliers. In this way a 
 smooth symmetrical cylinder may be made. If much operative work 
 is done it is well to have an assortment of soft gold cylinders of various 
 sizes and pellets of cohesive gold made up ready for use. In case an 
 assistant is available it is wise to make the preparation of the gold 
 a part of her duties. 
 
 In the use of the non-cohesive foil for fillings we may use it alone or in 
 combination with the cohesive foil. If it is used alone the cavity 
 should be of box form with four sides. The ideal cavity for the use of 
 non-cohesive gold is one in the occlusal surface of one of the molars. 
 The preparation of the cavity is no different from that in which the 
 cohesive gold is used. 
 
 For example, let us fill a cavity of the occlusal surface of a lower 
 molar. A half sheet cylinder is placed on end in the distal portion of 
 the cavity and pressed to place with a large foot plugger. In this 
 position the cylinder is placed on end, one end resting on the dentin of 
 the pulpal wall of the cavity and the other extending out of the cavity. 
 The cylinder should be long enough to extend out of the cavity 1 mm. 
 or 1| mm. The cylinder is made to rest on end because the leaves of 
 gold have no cohesion and will therefore not cohere to each other. If 
 
222 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 we placed the cylinder on its sides, with one of the sides extending out 
 of the cavity, the leaves of the cylinder would peel off and the filling 
 would in that way disintegrate; but if placed on end the sides of the 
 cylinder will be held in place by the other cylinders that are wedged 
 in place against it. 
 
 Fig. 149. — Cavity in lower molar pre- 
 pared for non-cohesive gold filling. 
 
 Fig. 150. — Same cavity with cylinder 
 in place in distal portion of same. 
 Cylinder standing on end. 
 
 The first cylinder is followed by other cylinders placed on end coming 
 forward to the center of the cavity when a cylinder is placed in the 
 buccal and lingual angles. It will now be advisable to place a cylinder 
 in the mesial angle of the cavity and thereby have the walls of the 
 cavity entirely filled, leaving an opening in the center. The cylinders 
 should be condensed toward the walls of the cavity all around, using 
 
 Fig. 151.— Cavity half fiUed. 
 
 Fig. 152. — ^Cavity filled with the excep- 
 tion of the key cylinder which is illustrated 
 beside the tooth. 
 
 hand-pressure and a strong wedge-shaped plugger. Keep on filling 
 around the sides of the cavity until it is impossible to introduce any 
 more of the half cylinders into the center. By the wedging process a 
 small opening will be left in the center that should be as deep as possible 
 and into this opening a tightly rolled half or eighth cylinder is forced 
 
FILLING TEETH WITH GOLD 
 
 223 
 
 to place, and the entire occlusal surface is now malleted with strong 
 mallet-pressure. In this way the whole mass of gold is thoroughly 
 condensed and the cylinders wedged together, keying the whole mass 
 to place, and, though there is no cohesion of the gold, by wedging the 
 cylinders tightly into a box-like cavity they are so thoroughly locked 
 into it that it is impossible for them to become dislodged. This form 
 
 Fig. 153. 
 
 -Cavity full of cylinders but 
 not condensed. 
 
 Fig. 
 
 154. — Gold condensed by hand 
 matlet. 
 
 of a filling makes one of the best fillings that can possibly be made, and 
 many of those made by the great operators of the past are still doing 
 splendid service. The only difficult part of this operation is the 
 making of the central key, and this difficulty is obviated by the use 
 of cohesive gold to make the center wedge. Into the opening that is 
 left in the center of the cavity, introduce a pellet of heated gold, which 
 
 Fig. 155. — Finished filling. 
 
 makes it cohesive, mallet this to place and fill the central opening full 
 of the cohesive gold, and then mallet the entire surface of the gold as 
 though it were all non-cohesive foil. A filling that would require a 
 long and tedious operation may be made in a very short time and 
 accomplished much more effectively than could be done by the use of 
 cohesive foil alone. 
 
224 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 Another place where the non-cohesive foil is of great advantage is in 
 the gingival thirds of cavities in the proximate surfaces of bicuspids 
 and molars. Three cylinders are usually used and should be of the 
 proper size to fit the cavity. In a fairly large cavity in a molar we would 
 use two cylinders of half-sheet each in the angles and one of quarter- 
 
 FiG. 1 56. — Cavity in proximate surface of bicuspid 
 ready for gold filling. 
 
 Fig. 157. — Non-cohesive cyl- 
 inders in bucco and linguo- 
 gingival angles. 
 
 sheet in the center. The cylinders having been selected, one of the 
 halves is taken in the pliers, slightly compressed and firmly tucked into 
 the linguo-gingivo-axial angle; then the other half is in like manner 
 placed into the angle on the buccal surface and between these two 
 cylinders is firmly wedged the quarter sheet cylinder of the non- 
 cohesive gold. The three cylinders should now be condensed with 
 
 Fig. 
 
 158. — ■ Central cylinder keyed in 
 between the two cylinders. 
 
 Fig. 159. — Cohesive foil beginning to 
 be built over the cylinders, note foil 
 built in step. 
 
 hand pressure, being careful not to push them out of the cavity. They 
 will be held in place by the approximating tooth, but can be dislodged 
 easily by pressure exerted in the wrong direction. The gingival portion 
 of the cavity is now filled and the operation has been accomplished in a 
 quarter of the time that would have been necessary to condense cohesive 
 
FILLING TEETH WITH GOLD 
 
 225 
 
 gold into the same place and the adaptation of the gold to the walls 
 of the cavity is as nearly perfect as it is possible to make it. 
 
 The filling should be completed with cohesive foil. Begin the filling 
 by starting a pellet of heated foil in one of the angles at the distal of 
 the occlusal step. The foil may be heated in several ways: it is 
 possible to heat over the open flame, using for that purpose a flame 
 
 Fig. 160. — Foil in step built over the 
 edge of the step and uniting with gold 
 built over non-cohesive cylinders. 
 
 Fig. 161. — Building of cohesive foil 
 finished but non-cohesive cylinders not 
 condensed. 
 
 in which the combustion is perfect and in which the gas burns with a 
 perfectly blue flame. The slightest evidence of imperfect combustion 
 is cause to reject the flame, for the products of the imperfect combustion 
 will be deposited upon the gold and will prevent a perfect cohesion, and 
 a flaky filling, or one that will break, will be the result. It is better 
 not to use the open flame for heating at all. Use either a mica or por- 
 
 Fig. 162. — Non-cohesive cylinders 
 condensed. 
 
 Fig. 163.— Finished filHng. 
 
 celain plate over the flame, upon which the gold may be placed and 
 heated as the operator proceeds with the filling. The best heater is 
 the electric, for with this there is plenty of heat to perfectly dissipate 
 the gaseous deposit placed there for the protection of the gold and 
 prepare it for perfect cohesion, and there is no danger of the contami- 
 nation of the gold by the products of imperfect combustion. 
 15 
 
226 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 The first pellet having been placed is malleted to adaptation and the 
 next built upon it. 
 
 There are several methods of condensing gold: the hand mallet in 
 the hands of a trained assistant, the hand mallet used by the operator 
 himself, the automatic plugger, the pneumatic engine and the electric 
 mallets. Each one of these has its advocates, and operators trained 
 in the use of the different mallets obtain splendid results with any of 
 them; but the hand mallet in the hands of a trained assistant holds 
 first place in the opinion of the authors. With it the amount and direc- 
 tion of force may be more easily and certainly adapted to the purpose 
 of condensation than with any other. In case the student does not have 
 an assistant he may choose the automatic plugger or use the hand mallet 
 himself, if he trains himself thoroughly in the use of the mallet, which 
 involves the use of the left hand in such an expert manner that he will, 
 with it, perfectly obtain his line of force and the proper amount of 
 hand-pressure. 
 
 The making of a gold filling means more than the mere adaptation 
 of the gold to the walls of the cavity. That may be perfectly accom- 
 plished and still the filling may be a failure. If the gold has not been 
 condensed to a degree that gives it a specific gravity of at least 14 it 
 will contain so great a percentage of air spaces that it will be little 
 more than a sponge and will not make an impermeable filling. It 
 requires considerable force to obtain a high degree of specific gravity 
 in malleted gold in a tooth. The specific gravity of gold is about 19.3 
 and a filling with a specific gravity of 18 will make a filling that is about 
 as nearly perfect as the hand of man can make it, so far as density is 
 concerned; but a filling with a specific gravity of 16 will make a very 
 good filling and few operators attain that. The reason that so many 
 gold fillings in the posterior teeth begin to pit and break down in a short 
 time is because of the low density of the filling, caused by the failure 
 to obtain sufficient mallet force in making the filling. Most of this is 
 caused by a failure to use the proper methods of condensation or by 
 improper use of those at hand. The reason we prefer to use the pellets 
 that we make ourselves is because we desire to know just the amount 
 of gold that is under our plugger point at a given time, for we know the 
 amount of force that a given quantity of gold must receive in order to 
 obtain a certain density. In order to obtain this definite density, 
 definite methods should be used. With the hand mallet used with a 
 force of ten pounds to the blow, augmented with a five-pound hand- 
 pressure on a plugger point that has a diameter of 0.5 mm. x 0.75 mm., 
 give 20 blows of the mallet to a sixty-fourth pellet, 40 to a thirty- 
 second, 80 to a sixteenth and 160 to an eighth. This method will give 
 the student and operator a definite method of obtaining a specific 
 
FILLING TEETH WITH GOLD 227 
 
 gravity that is as nearly perfect as he will be able to obtain. There 
 are always sources of error, of course. The thickness of the cushion 
 of the peridental membrane will cause quite a serious error in density 
 if it is great. For this reason it is very difficult to make a good hard 
 gold filling for children. The force of the condensing blow is so greatly 
 dissipated by the elastic cushion made by the thick peridental mem- 
 brane that it is inadvisable to attempt large gold restorations for 
 children. 
 
 Another source of error is the shape of the plugger. A long, thin 
 curved shank on a plugger will take up a very large amount of the con- 
 densing force of the blow in the elastic spring of the curved shank. 
 The plugger should be as nearly straight as it is possible to have it and 
 yet not have the point out of the range of vision. The shank should 
 not be long but as short as may be conveniently made. The pluggers 
 adopted by Drs. Woodbury and Crandall are as nearly perfect as it is 
 possible to obtain, and are the ones advised in this treatise. The size 
 of the plugger point is also of great importance for the amount of force 
 delivered at the plugger point is directly proportional to the force of the 
 blow and inversely proportional to the square of the plugger point. It 
 will thus be seen that an increase in the size of the plugger point rapidly 
 decreases the condensing power of the mallet. Use as small a point 
 as is consistent with good results. Too small a point chops the gold 
 instead of condensing it and too large a point fails in power of condensa- 
 tion. The ideal point is one that is about 0.5 mm. x 0.75 mm. 
 
 Cohesion and condensation are important, but unless the gold is 
 perfectly adapted to the walls of the cavity it wdll make no difference 
 how dense or compact the filling may be; it will fail because it will 
 leak. Perfect adaptation of the gold to the walls of the cavity is the 
 first desideratum. The other things must follow in the making of a 
 perfect filling. 
 
 The adaptation of the gold to the walls of the cavity is obtained by 
 the right use of the plugger in flowing the gold toward the walls of the 
 cavity. The first piece or two of gold having been started in the 
 convenience point or angle the other pellets follow in sequence, and as 
 they are placed the condensing force should be applied, beginnmg 
 toward the center of the cavity and stepping the plugger in an orderly 
 sequence toward the wall against which the gold is to be condensed. 
 Each step of the plugger should be about the distance of 75 per cent, of 
 the diameter of the plugger point so that the operator is shingling the 
 gold, each blow partly overlapping the preceding one until the wall of • 
 the cavity is reached, and then the plugger should be lifted up, retraced 
 toward the center of the cavity and again stepped toward the wall. In 
 tjiis way the gold is being continually forced toward the wall of the 
 
228 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 cavity and the last blow upon the gold is that which wedges it tightly 
 against the wall of the cavity. If the plugger started back from the 
 wall toward the center of the cavity it would be found that the gold 
 would be drawn away from the wall and a leaky place would be the 
 result. In this way pellet should be added to pellet, laminating the 
 gold back and forth, building up and forward until we come to the step 
 of the cavity leading toward the gingival surface. It will be remem- 
 bered that three cylinders of non-cohesive gold were placed in the 
 gingival surface and then no more attention was paid to them; but the 
 building of the cohesive gold in the distal portion of the occlusal step 
 was commenced. The cohesive foil is built forward over the non- 
 cohesive cylinders in the gingival seat, effectually locking them to 
 place. The gold is built up to occlusal and proximate form, correctly 
 contoured and the size and shape of the tooth restored as perfectly as 
 possible. 
 
 When inserting the non-cohesive cylinders it must always be remem- 
 bered to so place them, in any form of cavity, that the ends will be 
 extending out of the cavity and not the sides. This rule having been 
 adhered to in this case, we will find the ends of the cylinders tightly 
 resting against the approximating tooth. With a long, fairly wide 
 foot plugger the cylinders are malleted into the cavity by inserting the 
 foot plugger between the approximating tooth and the gold and making 
 strong condensation with the hand mallet. This drives the non- 
 cohesive cylinders tightly into the cavity and firmly against all margins, 
 and maintains a perfect adaptation at the gingival. 
 
 The use of the combination of non-cohesive and cohesive gold is 
 only possible in that class of cavities that will enable the cohesive gold 
 to be perfectly anchored in the tooth without the aid of the non-cohe- 
 sive gold, for there will be no cohesion between the two kinds of gold. 
 For instance, we use the non-cohesive foil in the gingival third of 
 bicuspids and molars because the non-cohesive cylinders may be keyed 
 into the cavity by condensing the cohesive foil over them and anchoring 
 the cohesive foil in the step in the occlusal surface. That retention 
 will be sufficient to retain the filling without the aid of the retention in 
 the gingival third. Also, in the occlusal surfaces of the molars, when 
 the non-cohesive foil is adapted to the walls of the cavity, the center 
 may be wedged with the cohesive and it will maintain itself, even 
 though there is no cohesion between the two kinds of gold. 
 
 In the case of a proximate cavity in an incisor it will be necessary to 
 use the cohesive foil entirely, because the cavity will need all of the 
 retention of the cohesive gold to maintain the filling. This is also true 
 of all fourth-class cavities, for in these there will not be sufficient 
 incisal anchorage to retain the filling if non-cohesive foil be used in 
 
FILLING TEETH WITH GOLD 
 
 229 
 
 the gingival third. The rule is to use the non-cohesive foil in only 
 those cavities in which sufficient anchorage may be obtained for the 
 filling after the non-cohesive foil is in place. 
 
 Class III cavities are filled with cohesive foil, beginning the filling by 
 placing a pellet, No. 32, in the linguo-gingival angle and slightly con- 
 densing it. At this point in the operation an assistant plugger is invalu- 
 
 FiG. 164. — Cavity ready for filling. 
 
 able. This may simply be any other plugger that is used to hold the 
 pellet of gold steadily in place, while the condensing force is being 
 applied, or, better still, it may be in the form of a gold carrier that is 
 used to pick up the pellet of gold, place it in the proper position and then 
 hold it steadily during condensation. The use of the combined carrier 
 and assistant plugger is a time-saver, in that the operation of picking up 
 
 Fig. 165. — Filling started in linguo- 
 gingival angle and built over the gingival 
 waU to the bucco-gingival angle. 
 
 Fig. 
 
 166. — Same process carried 
 farther. 
 
 the gold, placing it in the cavity and holding it in place is accomplished 
 with one instrument instead of two if pliers were used to carry the gold. 
 A very useful assistant plugger may be made by shaping a piece of 
 16-gauge iridio-platinum wire, sharpening it to a point and using it in 
 a good-sized broach carrier. The iridio-platinum will have the advan- 
 tage over steel in that it will not contaminate the gold with any dele- 
 
230 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 terious material. Other pellets are adapted to the first one, building 
 the mass of gold into the angle and gradually condensing the gold 
 across the gingival wall of the cavity. In placing each pellet the 
 condensing force should be begun at the point nearest the center of the 
 cavity and stepping the plugger toward the wall against which the gold 
 is being condensed at that particular time. Never step the plugger 
 
 Fig. 167. — Build up the filling, being 
 careful to keep the lingual portion in 
 advance. 
 
 Fig. 168. — Mesial angle built in. 
 
 away from the walls toward the center. The last blow of the plugger 
 should be at the extreme point of adaptation between the filling and the 
 wall of the cavity, thus calking the filling by wedging the gold between 
 that already condensed and the wall of the cavity. The assistant 
 plugger should hold the gold firmly to place during this part of the 
 condensation, for until the filling is built across the gingival seat and 
 
 Fig. 169. — Labial wall protected. 
 
 Fig. 170.— Finished filling. 
 
 firmly anchored in the labio-gingival angle, locking the gold in the 
 gingival to place there is danger of displacing the filling and causing 
 it to rock. If such an accident does occur, immediately remove the 
 gold already placed and begin over, for it will be almost impossible 
 to make an impervious filling after a portion has loosened from its 
 anchorage. 
 
FILLING TEETH WITH GOLD 231 
 
 When the filling is Ijuilt up along the gingival wall and thoroughly 
 locked to place the lingual wall of the cavity should be built up. The 
 lingual wall should be perfectly protected before much gold is added to 
 the body of the filling, for if this is not done there will be an insufficient 
 mass of gold along the lingual margin and it will be very difficult to 
 adapt it after the body of the filling is built up. Access to it from the 
 labial aspect will have been destroyed and the method of condensing 
 from the lingual surface will be found very difficult, if the filling is 
 started from the labial. After the lingual wall is well built the body of 
 the filling may be filled in, being very careful not to trap the labial wall 
 of the cavity without a sufficient quantity of gold to fill it, for there 
 again difficulty will be met in adapting the gold if there is no room to 
 do so. When the filling approaches the cavo-surf ace angle of the cavity 
 the gold should be lapped over the margin with a burnishing motion 
 of the plugger. No condensing force should be applied until a sufficient 
 mass of gold is in place to protect the enamel margin from the impact 
 of the plugger. If this were not done and the sharp serrations of the 
 plugger were driven through the thin mass of gold against the enamel 
 margin there would be grave danger of checking the enamel. When 
 the first pellet is burnished over the margin, condense up to the cavity 
 wall and then place another pellet and burnish it over the first, repeating 
 this operation several times, when a sufficient mass of gold will protect 
 the margin to allow condensation. The walls of the cavity having 
 been cared for, the filling should be contoured to form, the surface 
 thoroughly condensed and it is ready for the finishing. 
 
 The pluggers used in the condensation of both the non-cohesive and 
 the cohesive foils are the Woodbury-Crandall set of 26. This selection 
 of pluggers is most admirable and the student will find all of the points 
 necessary for any filling that he will be called upon to make. We can 
 do no better in giving a description of the pluggers and their use than 
 to use the words of the designers: Woodbury-Crandall gold pluggers 
 are designed for use in conjunction with a hand mallet in the hands of 
 an assistant. The forms are sufficient for any gold-foil operation, 
 though special forms may be added as conveniences rather than 
 necessities. 
 
 The set is made up of fourteen pluggers for cohesive gold numbered 
 from 1 C to 14 C ; nine pluggers for non-cohesive gold, numbered from 
 15 NC to 23 NC. Nos. 1 C and 2 C are for general work. No. 1 C 
 is used for starting fillings, filling very small cavities, convenience 
 points, etc.; No. 2 C for general open work in building up a filling after 
 it has been started. 
 
 Nos. 3 C and 4 C are for building along parallel walls, driving the gold 
 into sharp line angles and for general building. Their convex face 
 
232 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 causes the gold to spread more freely than a flat face does, thus obtahi- 
 mg more fully the effect of the wedging principle. These instruments 
 
 vmmrmmmwimgi/, 
 
 are also useful when approaching a margin, as their round face is not 
 likely to chip the enamel as a flat face. 
 
 Nos. 5 C and 6 C are for use in those locations that are not conven 
 
 so 
 
FILLING TEETH WITH GOLD 
 
 233 
 
 iently reached by Nos. 3 C and 4 C; their bends make them more 
 convenient, but also more springy. They are best used as auxiliaries 
 to Nos. 3 C and 4 C. 
 
 'M&MiimkUi Mil i li MMi'MUlML 
 
 No. 7 C is especially designed for filling the retention form in the 
 incisal angle and the labio-gingival angle of cavities in the proximate 
 surfaces of anterior teeth. 
 
 No. 8 C is convenient for use in the distal and occlusal surfaces of 
 bicuspids and molars. 
 
234 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 The form of No. 9 C allows the flat end of the plugger to bear upon 
 those places where it is necessary to incline the plugger to quite a degree 
 to reach different parts of the cavity. 
 
 Fig. 172. — Fourth class cavity ready for filling. 
 
 Fig. 173. — Starting in gingival angles and 
 building across gingival walls. 
 
 Fig. 174. — Continuing the building. 
 
 Fig. 175. — Progress. 
 
 Fig. 176. — Gold built up to incisal step. 
 Now starting in pit in mesial surface- 
 
 No. 10 C is used to reach inaccessible places, condense over angles, 
 smooth the surface of the gold, etc. 
 Nos. lie and 12 C are for use on the distal and occlusal surfaces of 
 
FILLING TEETH WITH GOLD 
 
 235 
 
 bicuspids and molars, the long angles allowing almost any part of these 
 surfaces to be reached with a correct line of force. 
 
 Fig. 177. — Built over incisal surface and 
 anchored to body of filling. 
 
 Fig. 178.— Gold all built in. 
 
 Fig. 179.— Finished filling. 
 
 Fig. 180. — Class V cavity ready for 
 filling. 
 
 Fig. 181. — Gold started in disto-gingival 
 angles and built up to disto-mesial angle. 
 
 Fig. 182.— Gold built over floor of 
 cavity. 
 
 Nos. 13 C and 14 C are back-action pluggers, intended for use only 
 in locations that cannot be reached with a correct line of force with 
 direct-action pluggers. These two instruments have twelve-inch 
 handles, with hard-rubber grips. 
 
236 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 Nos. 15 NC to 23 NC, for non-cohesive gold, should never be used 
 for cohesive gold, as they have faces so large that cohesive gold cannot 
 be condensed with them. 
 
 Fig. 183. — Process continued. 
 
 Fig. 184. — Building gold over cavo- 
 surface angle, burnishing it over to 
 obtain mass before malleting. 
 
 Fig. 185. — ^All cavo-surface angles 
 protected. 
 
 Fig. 186.— Gold all built in. 
 
 Fig. 187.— Finished filling. 
 
 Nos. 15 NC and 16 NC are used to drive the non-cohesive cylinders 
 against the gingival wall and into the axio-gingival line angle in cavities 
 in the proximo-occlusal surfaces of bicuspids and molars. 
 
 No. 17 NC is used for driving the cylinder against the axial walls 
 in cavities in occlusal surfaces. 
 
FINISHING THE FILLING 237 
 
 Nos. 18 NC and 19NC are used for driving the cylinders farther into 
 the cavity from the occlusal surface after the filling has otherwise 
 been made. 
 
 Nos. 20 NC and 21 NC are for use in cavities in the proximo-occlusal 
 surfaces, mesial aspect, for driving the cylinders in the interproximate 
 space against the axial wall, after the filling has been otherwise com- 
 pleted. 
 
 Nos. 22 NC and 23 NC are back-action pluggers for use on distal 
 surfaces in the same way that 20 NC and 21 NC are used on mesial 
 surfaces. They have twelve-inch handles with hard-rubber grips. 
 
 FINISHING THE FILLING. 
 
 The filling should be finished with as perfect a polish as that which 
 nature gives to the enamel of the tooth for the reason that food debris 
 will not cling to a polished surface as well as to a rough or uneven one. 
 All margins of the filling should be flush with the tooth surface so that 
 an explorer will not catch between the tooth and filling when lightly 
 passed over the surface. This is particularly true of the finish at the 
 gingival margin, for here a rough or overhanging margin will be the 
 cause of a considerable irritation to the gingival tissue with a resulting 
 inflammation and a not infrequent pyorrhea. Many teeth have been 
 lost by the careless placing of a filling with rough overhanging margins. 
 Dr. Arthur Black and others have demonstrated that many cases of 
 pyorrhea have had their inception in such faulty operations. It is 
 therefore essential that the filling should be finished as perfectly as 
 possible. The first point in the operation of finishing the filling is 
 trimming to form. The contour of the tooth and the true anatomic 
 form of the occlusal surface should be accurately reproduced. In 
 order to do this, the student must possess the knowledge of tooth form, 
 for without an accurate conception of the form of the tooth, he will not 
 be able to reproduce it. 
 
 In finishing fillings placed in the occlusal surfaces of molars and 
 bicuspids, the filling should be ground down to approximate occlusion 
 with a suitable carborundum stone of the proper size. It should not 
 be too large to be of service in bringing the surface of the filling to a 
 relatively close approximation of the form desired, nor should it be so 
 small that it will be likely to cut the surface of the filling and make it 
 irregular. After the stone has brought about an approximation of the 
 result desired, a round finishing bur is used to carve the surface of 
 the tooth making therewith the sulcus and grooves thus making the 
 surface of the filling correspond with the surface of the natural tooth. 
 The skill and artistic ability of the operator can be given full play at 
 
238 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 this point and results beautiful, as well as useful, will follow in the 
 train of a well-executed finish. After the filling is trimmed to form and 
 occlusion, as well as to anatomic correspondence, it should be well 
 polished. This can be accomplished by the use of the rubber cups 
 
 Fig. 188. — G. V. Black's adjustable saw frame. 
 
 charged with wet pumice and rapidly revolved in the engine hand piece. 
 If a high polish is desired the wet pumice may be followed by dry 
 pumice, used with the same instrument to be followed by any of the 
 tooth powders, also used dry. This will give a very high polish, but in 
 
 Fig. 189. — G. V. Black's finishing files and knives. 
 
 the opinion of the authors is contra-indicated in all fillings that come 
 within the range of vision for a highly polished gold filling will so absorb 
 the rays of light that it will look almost black. The best way to leave 
 the filling is with the w^ll snioothed surface that is obtained hy the use 
 
FINISHING THE FILLING 239 
 
 of the wet pumice, or a very fine sandpaper disk. This leaves a surface 
 that does not look dark but on reflection of light shows in its true 
 color. 
 
 In finishing a filling in the proximate surface of a molar or bicuspid 
 the approximate form is reproduced by the use of a Black saw, knives 
 and files. The Black saw is one of the most useful instruments ever 
 devised for the finishing of the proximate surface of gold fillings. It is 
 a heavy saw frame into which is inserted a Kaeber saw, which has been 
 ground down upon its smooth edge until the saw is of thread form. 
 The grinding of the saw is accomplished by inserting it in the saw frame 
 and holding the back of the saw against a carborundum stone in the 
 engine or lathe until the desired width has been secured. The entire 
 back of the saw is ground down with the exception of the portions that 
 engage with the saw frame, for if these were ground down the saw 
 would not maintain itself in the frame when it was in use; therefore, 
 the ends of the blade should be left as they come from the manufac- 
 turer. 
 
 In use the saw blade is inserted into the interproximate space, above 
 the filling, with the teeth toward the occlusal surface. If there is not 
 room to insert the saw, space can be made by cutting out a portion of 
 the gold with a Black knife. These knives are illustrated in the 
 Woodbury-Crandall set as Nos. 34 and 35. The saw is inserted and 
 the frame attached to it as it is in its position between the teeth. This 
 is necessary for the reason that we wish to cut the gold out of the inter- 
 proximate space, but do not want to cut away any of the contact. 
 Therefore, the saw must be inserted above the filling and the gold 
 removed from the interproximate space by sawing from the gingival 
 margin toward the occlusal surface. In this way the surplus gold 
 can be easily and most expeditiously removed from the interproximate 
 space with ease to the operator and comfort to the patient. The cutting 
 with the saw must stop short of the contact, for to cut through that 
 would be to ruin the form of the filling. When the gold is removed 
 to the contact point the saw should be disengaged from the frame and 
 drawn out of the interproximate space by pulling it out of the buccal 
 embrasure. The contour form is finished by the use of the Black files, 
 or those designed by Dr. J. M. Prime. With these files the form of the 
 filling may be made to conform perfectly to the shape of the tooth, 
 being careful to make all the lines of the filling slope toward the contact 
 point, which should not be finished until the last. With the Black 
 knives, careful search should be made for any overhang, and if any 
 is discovered it should be removed and the gingival margin made 
 perfectly flush and smooth. The occlusal form should be reproduced 
 with stones and burs as in an ordinary occlusal surface filling, being 
 
240 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 very careful to see that the marginal ridge is maintained. If the 
 marginal ridge is not reproduced and the sulcus made so that the bolus 
 in its excursion over the tooth in mastication is driven toward the 
 middle of the tooth and out of the sides of the embrasure instead of 
 toward the contact, there will be a very great probability of the food 
 finding its way between the contacts and into the interproximate 
 space, to the great detriment of the septal tissue and the inconvenience 
 and pain of the patient. For this reason, the occlusal surface of the 
 tooth should never be ground flat as has been the custom of many 
 good operators in the past. Nature made the form of the tooth not 
 only for the purpose of the mastication of the food, but also so shaped 
 it that in the process of mastication that function could be normally 
 accomplished without harm to the investing tissues. 
 
 If the separator is in position it should now be tightened a little, in 
 order to obtain a little more space to finish the contact point. If it is 
 not on, it should be placed and the desired space obtained. Very little 
 finishing of the contact point is needed, for if the work thus far has been 
 properly done the whole of the filling is finished to form, and as all of 
 the lines of the filling slope toward the contact, that point will be but a 
 point indeed, and all that will be required to finish it will be to obtain 
 the requisite space and pass a polishing strip between the points and a 
 few moments of the same will finish the operation. In the use of 
 sandpaper disks for finishing the fillings in the posterior teeth the right 
 angle mandrel is indispensable, for the proper angle of approach cannot 
 be obtained by the use of the straight hand-piece. In the use of the 
 right angle the operator will immediately see many of its advantages 
 and will soon add places in which he will find the instrument of the 
 greatest assistance. The interproximate portions of the filling may be 
 polished with a fine strip, the rest of the filling disked and the whole 
 polished with the rubber cup and wet pumice. When the separator 
 has been removed and the teeth have resumed their normal relation 
 the contacts should be so tight that a piece of floss silk will pass between 
 them with a decided snap. 
 
 Fillings in the proximate surface of incisors are finished to form with 
 files and knives, the gingival space polished with a sandpaper strip, 
 and the labial and lingual portions disked with the aid of the right- 
 angle mandrel, after which separation should be made and the contact 
 polished with a fine strip. 
 
 In the use of the sandpaper strip it should be cut on one end to a 
 narrow point, that it may be threaded in between the teeth into the 
 interproximate space. Then, in the posterior teeth especially, it is 
 caught in the end of a split instrument that engages the end of the strip, 
 which when wound around the instrument is held fast and the operator 
 
AMALGAM 241 
 
 using the instrument in the mouth to hold the strip and managing the 
 other end with his hand is enabled to use the strip with more ease and 
 certainty. 
 
 The instrument may be made by taking an old excavator and cutting 
 a slot in the end of it about 4 or 5 mm. deep and wide enough to 
 accommodate a strip easily. 
 
 At no place in performing an operation does the finished product 
 display the skill of the operator so much as in the form and finish of 
 the filling. It therefore behooves every dentist to survey more critically 
 his own handiwork in the light of the finished product, and strive more 
 earnestly to make the finish of a gold filling perfect. 
 
 AMALGAM. 
 
 Amalgam is an alloy of any metal with mercury. In dentistry it 
 may be an alloy of copper and mercury making the copper amalgam, 
 or it may be an alloy of two or more metals with mercury, as in the 
 silver tin alloys, which are in general use by the profession today. 
 Copper amalgam has many points of superiority in that it will neither 
 shrink nor expand, and, by reason of its great plasticity, is easily 
 adapted to the walls of a cavity. It is used very sparingly in dentistry 
 today because of the fact that it rapidly wears out of the cavity and also 
 because of its black color. In the filling of deciduous teeth, however, 
 it has a place that is entitled to respect, for here it usually maintains 
 its integrity as long as it is wanted; also the antiseptic action of the 
 copper salts makes it a very valuable aid in saving children's teeth 
 when utility for a short space of time is paramount to appearance. 
 
 The silver tin alloys are the ones in general use, and the reader is 
 referred to Chapter VII for a study of the physical characteristics, 
 formulse and methods of manufacture. This article will attempt to 
 illustrate only the technic of the filling of teeth with amalgam, leaving 
 all discussion concerning its properties to the author of the chapter on 
 that subject. 
 
 The preparation of the cavity for the reception of a filling of 
 amalgam is identical with that for a gold filling, except that the cavo- 
 surface angle is made wider to allow a greater mass of amalgam at 
 the edge of the filling, thus giving the filling greater edge strength. The 
 reader is therefore referred to the article on the preparation of cavities 
 for gold fillings by the authors of this treatise. 
 
 By reason of the color of amalgam, its use is not indicated in the ante- 
 rior teeth and should be used rarely, if ever, anterior to the first molar. 
 If the filling preserved its color at all times it would not be so objec- 
 tionable, but old amalgam fillings invariably become much discolored, 
 16 
 
242 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 making their use anywhere within the range of vision, a very doubtful 
 practice. If the filling is well made and there is no infiltration of moisture 
 between the filling a,nd dentin there will be no discoloration of the tooth, 
 but if there is a leakage, no matter how slight, there will be a discolora- 
 tion of the dentin, owing to the formation of sulphids, and the penetra- 
 tion of the dentin by the resulting sulphids. This coloration may vary 
 from a slight grayness near the margin of the filling to a dense blue- 
 black of the entire tooth. A result of this kind is indicative of faulty 
 manipulation of the amalgam under the plugger, hence the necessity 
 for a care ul technic in condensing the filling. 
 
 In order to successfully fill a cavity with amalgam it is necessary to 
 have four walls, for it cannot be perfectly condensed unless confined 
 to the cavity while pressure is being made. All simple occlusal cavities 
 have four walls and can therefore be filled without any complications, 
 but cavities in the proximate surfaces of molars and bicuspids should 
 
 Fig. 190. — Copper matrix and cavity. 
 
 be supplied with the lost wall. This is accomplished by the use of a 
 matrix of some sort. The matrix that is made for the particular case 
 under consideration is advised. 
 
 Such a matrix is made by taking a piece of thin sheet copper, of 36 
 gauge, and cutting an oblong piece that will conform to the length of 
 the tooth and be long enough to encircle the tooth to about two-thirds 
 of its diameter. A small wing is turned up at each of the corners that 
 are to be at the gingival portion of the tooth to be the recipient of the 
 matrix, for the purpose of holding the ligature and preventing it from 
 slipping off the matrix into the gum. The matrix is now adapted to 
 the tooth and a piece of floss silk thrown around it, making a double 
 turn of the silk. This is drawn tight, carefully watching to see that the 
 matrix is being properly adapted to the tooth. Too much stress should 
 not be applied to the silk or it will cause the matrix to be pushed into 
 the cavity on the proximate aspect of the tooth. After the matrix is 
 
AMALGAM 243 
 
 ascertained to be in proper relation to the tooth and cavity, and it is 
 seen that it properly restores the lost wall of the tooth, the ligature 
 should be tied and the matrix held perfectly in place. If the matrix 
 does not fit at the gingival margin it is advisable sometimes to adapt 
 a small orange-wood wedge at the gingival margin to hold the matrix 
 
 Fig. 191. — Matrix tied on. 
 
 firmly to place and prevent the amalgam being forced between the matrix 
 and the tooth into the gum. If this happens, and it is not discovered 
 and removed, it will cause a very sore tooth and the possible loss of the 
 same by the severe inflammation which such an irritant may cause. 
 The matrix should now be contoured from within the cavity with a 
 small ball burnisher and the contact made by cutting a hole in the cop- 
 per matrix with a No. 4 round bur. This will leave a hole at the con- 
 
 Matrix wedged at gingival. 
 
 tact point which will enable the operator to condense the amalgam at 
 that point directly against the approximating tooth, preventing the 
 displacement of the amalgam and making it possible to obtain a very 
 tight contact. The cavity should be prepared, dam in place, matrix 
 adapted and all things in readiness before the amalgam is mixed. 
 
244 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 When making an amalgam filling the point of greatest interest is the 
 choice of the alloy, for failure to use a good alloy will cause a failure of 
 the filling. The operator may do some things perfectly, but no man 
 can operate a faulty alloy in such a way that he can make a filling that 
 will stand the stress of time and mastication. At the present time, 
 happily, there is little need of making a faulty selection. Expansion 
 and shrinkage of the filling is out of the hands of the operator and in 
 the hands of the manufacturer, but the strength or weakness of the 
 filling is largely an operative procedure. Too much mercury in the 
 mix, so that a sloppy mass is the result, will make a weak filling, while 
 too little mercury will also make a weak filling and one that has a 
 tendency to be very brittle. Therefore, to make a strong filling it will 
 be safer to have the proper amounts of alloy and mercury at each mix. 
 This is accomplished by weighing the separate parts of the mix on a 
 balance, first ascertaining the proportion of alloy and mercury to take 
 for the particular alloy that is to be used. This can be done by 
 experiment, finding the amount of mercury that will give the proper 
 consistency to a definite amount of alloy. The amalgam that gives the 
 best results is a mix that, when well kneaded, will leave the print of 
 the fingers well outlined on the mass. When the proper amounts to 
 produce this consistency have been obtained it is advisable to weigh 
 out a number of such units of alloy and place them in ordinary gelatin 
 capsules and set them aside until wanted. The same may be done 
 with the mercury. The proper amount of mercury is weighed and 
 placed in capsules; when a filling is to be made a capsule of alloy and 
 one of mercury are taken and the mix made from them. If the proper 
 amounts have been ascertained and carefully weighed out there will 
 be approximately the right mixes every time without the care and 
 thought whenever a filling is to be made. 
 
 The alloy and mercury are placed in a good-sized Wedgewood mortar 
 and thoroughly triturated until a good amalgamation has been secured, 
 when the mass is turned into the hand and kneaded thoroughly for some 
 time until a perfectly homogeneous mix is obtained, which, as has been 
 said, is evidenced by the fact that the resultant mass will reproduce 
 the marks of the fingers upon its surface. There is one school of 
 amalgam operators that teaches that the filling should be made from a 
 mix that is so soft that it is sloppy in order to obtain a more perfect 
 adaptation, while another school insists upon the use of a mix that is so 
 stiff that it is almost impossible to get it into the cavity before it has 
 set. Neither school is correct, for the sloppy mix, while seemingly 
 easier to adapt to the walls of the cavity, in reality is not so, and the 
 fact that such a mix is bound to make a filling that will be too weak 
 to stand the stress of continued use would be enough to discredit it. 
 
AMALGAM 
 
 245 
 
 The too stiff mix is so difficult to manipulate that the majority of fillings 
 made with it will be found of faulty adaptation. The better way is to 
 choose the medium mix which will make possible a good adaptation 
 and a strong permanent filling, if properly condensed. This mass 
 should be broken into several fragments and is ready for the filling.^ 
 
 The instruments that are used in condensing the amalgam are those 
 selected by Dr. Crandall. We reproduce the illustrations and explana- 
 tion of their use by their designer: 
 
 15 
 
 40 
 
 50 
 
 60 
 
 SO 
 
 30 
 
 18 
 
 35 
 
 50 
 
 so 
 
 8 
 
 10 
 
 10 
 
 12 
 
 12 
 
 
 
 
 
 
 
 
 
 
 
 10 
 
 11 
 
 12 
 
 13 
 
 14 
 
 3 
 
 6 
 
 20 
 
 20 
 
 15 
 
 16 
 
 Fig. 193. — Walter G. Crandall's'amalgam'condensers. 
 
 These instruments have been designed to fit into the proximate and 
 occlusal portions of such cavities as are usually made in bicuspids and 
 molars for amalgam fillings. They have shortened shanks, bringing 
 the working point of the instrument closer to the grasp that controls 
 
 1 The reader is referred to the section on Amalgam, in Chapter VIII, for a further 
 discussion of this subject. 
 
246 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 it and affording great leverage and very accurate control. When used 
 as pluggers to carry a mass of amalgam and to condense it under heavy 
 hand pressure supplemented by mallet force, they will produce the 
 greatest possible density and strength in the completed restoration. 
 
 Nos. 1 to 7 are for cavities in the lower teeth which are inaccessible 
 with the bayonet-shaped instruments, Nos. 8 to 14. 
 
 Nos. 7 and 14 are especially valuable, as their size allows them to 
 condense a mass of amalgam over all of the margins of the cavity 
 simultaneously, thus avoiding the movement away from some portion 
 of the margins which is always produced by the use of small pluggers. 
 
 Nos. 15 and 16 are amalgam formers, used for reducing the excess of 
 amalgam to the cavity margins and for preliminary carving in the 
 restoration of the natural tooth form. 
 
 A piece of amalgam about the diameter of the cavity is taken in the 
 pliers and carried to the cavity, where it is pressed into place with the 
 finger, and pressed firmly to the floor of the cavity by a plugger as large 
 as the entrance will permit. Then a slightly smaller plugger is used to 
 condense the amalgam against the walls, carrying the material from 
 -the center of the cavity toward the walls thereof, as is done in condens- 
 ing a gold filling; then wedge the next piece in between the amalgam 
 condensed against the walls, thus taking advantage of the wedging 
 principle in forcing the material more tightly in its adaptation to the 
 walls of the cavity. This should be continued until the cavity is full, 
 when a piece of amalgam slightly larger than the orifice is placed on 
 the filling and heavy pressure made with a large plugger, which may 
 in some cases be advantageously augmented by the mallet. The 
 filling is made more dense and strong in proportion to the pressure 
 made upon the amalgam during the packing of the filling. Dr. South- 
 well, many years ago, demonstrated the fact that very few amalgam 
 fillings were able to withstand a pound of air-pressure without leaking, 
 because their adaptation to the walls of the cavity was so poor, and 
 Dr. Crandall admits that the packing of an amalgam filling in order 
 to make it impervious to moisture is a very difficult operation. It 
 therefore behooves the student to study the technic of the packing and 
 condensation of amalgam with the greatest care if he expects to make a 
 success of its manipulation. 
 
 The amalgam should be allowed to set for several minutes until it 
 has become fairly hard before the matrix is removed, and then care 
 -must be exercised not to break the filling in removing it. If a hole has 
 been made in the copper at the point of contact, and the portion of the 
 matrix extending gingivally above the surface of the filling has been cut 
 . before the matrix is applied, the matrix can usually be torn asunder 
 after the amalgam has hardened, parting at the point where the hole 
 
AMALGAM 247 
 
 was made for the contact, when the two ends can be withdrawn easily 
 from the buccal and lingual surfaces and the filling left undisturbed. 
 If there is any danger of breaking the filling it is better to allow it to 
 set until it has become perfectly hard, when it may be manipulated 
 as desired. 
 
 The reason that it is desirable to remove the matrix before the 
 amalgam has become perfectly hard is that it may be carved to form 
 much more easily before it attains its hardness. 
 
 After the removal of the matrix the filling should be carved to con- 
 tour with the Black knives and polished with a fine sand-paper strip, 
 inserting the strip between the teeth gingivally to the contact point. 
 This can be done more expeditiously if the strip is cut to a point and 
 then threaded into the interproximate space, as advised in the finishing 
 of a gold filling. 
 
 The occlusal surface of the filling should be made to resemble the 
 natural tooth as closely as possible, and in this work the art of the 
 operator can be beautifully demonstrated in the carving of the cusps 
 and sulci. The carving of an amalgam filling is so easly done thatjthe 
 making of a flat occlusal surf ace on an amalgam filling is little short of 
 malpractice. It is certainly indicative of gross carelessness. 
 
 When the filling is carved to form it is advisable to dismiss the patient 
 and polish at a future sitting, when the filling should be disked to 
 smoothness and polished to a mirror surface by the use of rubber cups 
 and pumice, first used wet and then dry for the final polish. An 
 amalgam filling so made will give the patient years of useful service 
 and will, in a high degree, resist the deposits of food debris upon its 
 surface due to the high polish which it will take and retain. 
 
 In many badly broken-down teeth that would usually require crowns 
 the amalgam filling can be used to restore the tooth to usefulness better 
 than a crown. In these cases the cavity is prepared with all the 
 retention that is possible, cutting down the cusps and reinforcing them 
 by carrying the metal over their surfaces and restoring them with the 
 amalgam. Frequently in those cases where the pulp has been involved 
 and the canals filled the pulp chamber can be utilized for retention and 
 the foundation of the filling made in it. When the cavity is prepared 
 a copper band is made to fit the case or a ready-made band is chosen 
 and adapted to the tooth, carefully festooning the metal where it would 
 otherwise impinge upon the gum. The band is contoured as well as the 
 skill of the operator will permit, which can be done more easily if 
 the band is slit gingivally from the contact, thus enabling the ligature 
 to adapt it more closely to the tooth. The band will be allowed to 
 remain upon the tooth for a day after the filling has been made. 
 
 The contact points should be made possible by cutting a hole in the 
 
248 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 band at the proper point with a round bur and the cavity is ready for 
 the fining. Sometimes it is difficult to adjust the dam before the band 
 has been placed. If so it will be an easy matter to place it after the 
 band is on the tooth, for it will take the form of the tooth and the 
 rubber can be slipped over it. 
 
 Fig. 194. — Copper tube festooned, trimmed and prepared for mesio-occluso-distal 
 
 cavity. 
 
 The amalgam can now be packed into the band using all the care that 
 we would use in the packing of an ordinary filling. The occlusal sur- 
 face should be carved to form while the amalgam is still plastic, but the 
 remainder of the finishing would better be left until the following day. 
 The band should be left in place until that time, for the attempt to 
 
 Fig. 195. — Matrix adjusted and tied. 
 
 remove it would be likely to break the filling and spoil the entire opera- 
 tion. When the case is seen the next day the band should be split 
 with a sharp knife and removed and the filling dressed to shape 
 with stones, disks and strips and polished to a mirror surface. This 
 operation when completed will be of better service than that given 
 
GUTTA-PERCHA AND THE CEMENTS 249 
 
 by a crown, for the gingival margin is smoother and less liable to irrita- 
 tion. In all operations, whether with amalgam or any other material, 
 one of the objects of the greatest importance is to obtain a smooth and 
 polished surface at the gingival margin, for the delicate septal tissue 
 will not tolerate the slightest roughness. The beginnings of pyorrhea, 
 as Drs. G. V. and Arthur Black and others have pointed out, lie in the 
 rough gingival margins, due either to faulty dental operations or to 
 the deposition of calcareous substances thereupon. If the cause is a 
 faulty dental operation it is a stigma upon the operator and one that 
 the student should teach himself to abhor. 
 
 In summing up, making an acceptable amalgam filling consists of 
 a proper cavity preparation, choice of a good alloy, the proper manipu- 
 lation of the alloy and mercury, adaptation of a well-made matrix, the 
 condensation of the filling, the removal of the matrix and shaping of 
 the filling and the polishing of the filhng. 
 
 GUTTA-PERCHA AND THE CEMENTS. 
 
 Gutta-percha is a very valuable temporary filling, but is not used 
 with any idea of permanency. It is used principally as a sealing for 
 the various medicaments used in the treatment of teeth and as a stop- 
 ping in cavities after the wax pattern is made for an inlay, and the 
 patient has been dismissed for a future sitting. It is also very useful 
 in making separations where the teeth have fallen together by reason 
 of extensive decay, and it is necessary to separate them for a time in 
 order to produce sufficient space to restore properly the mesio-distal 
 diameter of the tooth. It may also be used as a temporary filling in 
 any case that may be desirable, but not with any thought of per- 
 manency. 
 
 The cavity preparation for gutta-percha is the same as for any of the 
 plastics; therefore it will not be necessary to go into that subject in 
 this treatise. 
 
 In filling the cavity with gutta-percha it is necessary to have the 
 cavity dry, for the material will not adhere to a wet surface. It is well 
 to moisten the cavity with the oil of eucal}T)tus or oil of cajuput prior 
 to the introduction of the filling, for these oils have the power of dis- 
 solving gutta-percha and making it adhere to the surface of the tooth. 
 The gutta-percha should never be softened in the flame, for to do so 
 will endanger its structure by overheating and consequent disintegra- 
 tion. If too high a degree of heat is used it will catch fire and burn. 
 The best way to soften it is to place small pieces of the material on a 
 heating tray for gold, such as the mica that is used over an alcohol 
 lamp to heat gold or if the Custer gold annealer is at hand it may be 
 
250 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 used conveniently by placing a piece of porcelain or glass upon it and 
 allowing the electricity to heat the porcelain to a moderate degree, when 
 
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 n .^ njU 
 
 
 uin" f 
 
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 SI 1 
 
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 f'Sl'S 
 
 £S nn 
 
 J»" ! 
 
 Hi 
 
 ii 
 
 1 1 
 
 f.-sisg 
 
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 IS : 
 
 Fig. 196. — Rivet plastic instruments. 
 
GUTTA-PERCHA AND THE CEMENTS 251 
 
 the heat is turned off and the gutta-percha placed on the porcelain. 
 It will remain warm sufficiently long to make the filling, keeping the 
 gutta-percha plastic, the very best possible condition for use. 
 
 A suitable set of instruments for the introduction of the gutta-percha 
 and cements is one here illustrated. The set should consist of smooth 
 end pluggers of slightly curved and bent angle shape in order to make 
 convenient the placing of the material in any cavity no matter where 
 situated; also, an assortment of smooth blades of slightly curved form 
 for the trimming of the material in the proximate surfaces. 
 
 Gutta-percha should be inserted in the cavity in small pieces and 
 adapted to the walls in the same way as an amalgam filling, that is, the 
 material should be forced from the center of the cavity toward the 
 walls thereof and the following pieces inserted in the space in the center 
 made by condensing the material toward the walls of the cavity, this 
 procedure to be followed until the cavity is full. The filling may be 
 trimmed to form with the warm instrument, for to attempt to cut the 
 gutta-percha with a cold instrument will pull the material away from 
 the walls of the cavity and make a very ragged surface. After the 
 filling is trimmed to form it may be further smoothed by taking a firm 
 piece of cotton pellet and washing the surface of the gutta-percha with 
 eucal3q3tus or cajuput. 
 
 In placing gutta-percha over dressings in the tooth it is necessary to 
 use a great deal of care not to make pressure upon the medicament 
 that is used, for if over a pulp, pressure will cause a great deal of pain, 
 and if over a dressing placed in the pulp cavity in the treatment of 
 root canals the pressure may cause a portion of the medicine to be forced 
 through the apical foramen, causing intense irritation and pain. This 
 may be obviated by the careful manipulation of the material. x\ 
 small piece should first be used and placed over the medicine saturated 
 cotton and lightly packed to place with a warm instrument that has 
 been moistened with eucalyptus. After this piece has been allowed to 
 harden more of the material may be introduced, but care should be used 
 all through the operation not to use too much pressure. 
 
 Gutta-percha is invaluable for making a temporary filling in a cavity 
 that has been prepared for an inlay until a convenient time may be 
 obtained for the setting of the same. In such cases the filling should 
 be made with as much care as if it were to endure for a longer period 
 for if the gutta-percha is carelessly jammed into the tooth and up into 
 the interproximate space it will crowd out the septal tissue and may 
 cause considerable pain as w^ell as a great deal of damage. 
 
 Gutta-percha is of great value in those cases in which the gum tissue 
 has crowded into a cavity in a tooth that has had the decay progress 
 below the gum and has caused such a gingival irritation that the 
 
252 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 gum has hypertrophied to such an extent that it partly or entirely 
 fills the cavity. In many cases it is possible to cut out the tissue; 
 but some cases do not call for that treatment, when a gutta-percha 
 plug may be inserted and the patient instructed to call again the 
 next day. If the tissue has been displaced to the extent desired a 
 temporary filling of the gutta-percha may be inserted, care being used 
 not to impinge upon the septal tissue and the patient dismissed until a 
 time desirable for finishing the operation. If the tissue is not suffi- 
 ciently displaced crowd in a little more gutta-percha until the gum is 
 entirely clear of the cavity and then it may be filled as usual. 
 
 In the separation of teeth which have fallen together by reason of 
 decay the material may be crowded into the cavity between the teeth, 
 leaving it a little overfull, so that the patient will bite upon the filling. 
 In doing this a constant pressure will be made against the two teeth and 
 will crowd them apart. This plug may be worn for a few days and then 
 replaced with a new one that is again a little more than full ; this treat- 
 ment should be repeated until the proper amount of space has been 
 obtained. 
 
 CEMENTS. 
 
 The cements used in dentistry are the oxyphosphates of zinc and 
 copper and the silicates. The student is referred to Chapter VII for 
 a description of the chemical and physical characteristics. The present 
 article will only comprehend the use of cements in dentistry. 
 
 Practically the only use of cements for the filling of teeth is of a 
 temporary nature, for the permanent cement is still to be found. 
 The silicates are more nearly permanent, but the silicate that will 
 stand the test of permanency is yet to be brought to the attention of 
 the profession. It is a great mistake that will undoubtedly refiect 
 upon the reputation of the practitioner to tell a patient that any 
 cement is permanent. 
 
 It may be good practice to use the silicates, for their esthetic effect 
 is good and many patients prefer it to the unsightly effect of gold; but 
 it is always advisable to warn the patient that the filling may have to 
 be remade from time to time, depending upon the condition of the 
 fluids of the mouth of the patient under consideration. If the patient, 
 with this understanding, chooses to have the silicate used, well and good, 
 but a patient should never be told that any cement filling is as nearly 
 permanent as some other materials. 
 
 The preparation of the cavity for a cement filling is the same as for 
 any other filling except that the cavo-surf ace angle demands a different 
 treatment, owing to the slight edge strength possessed by the cements. 
 
CEMENTS 253 
 
 The cavo-surface angle should be without bevel and should always 
 follow the long axis of the enamel rods, so that there will be no short 
 rods upon the surface of the cavity, and there will be no sharp angle 
 to make a thin portion of cement at the edge of the filling, for to do so 
 will be to cause the edge to break away and leave a vulnerable point 
 for the beginning of a recurrent decay. 
 
 For a filling of any kind, the silicates are usually to be preferred, as 
 they are less soluble, are harder, decidedly more harmonious in color 
 and will make a more lasting filling than one made of any of the 
 zinc cements; therefore, in the description of the filling of teeth with 
 cement the silicates are understood. 
 
 The filling must be made under the most exacting conditions of 
 dryness, for the slightest amount of moisture before the cement has set 
 is inimical to good work and the lading quality of the material. The 
 rubber dam should therefore always be placed upon the tooth before 
 the operation and the cavity dried thoroughly. It is nearly always 
 advisable to use a matrix of some kind. A matrix made of celluloid is 
 preferred, as it imparts a smooth, polished surface to the filling and 
 does not endanger the color by imparting any deleterious product to 
 the cement during its manipulation as a metal matrix might. The 
 slightest foreign substance incorporated with the cement will endanger 
 its integrity and will be likely to cause a discoloration of the filling. 
 
 If the filling is to be made in the proximate surface of an incisor a 
 strip of thin celluloid is inserted between the surfaces of the teeth on 
 the side opposite the one that is to be filled, and then one end brought 
 around the lingual surface of the tooth and carried over the cavity. 
 To illustrate: if a cavity presents in the distal surface of an upper left 
 central incisor one end of the celluloid strip should be inserted between 
 the two central incisors and the other end carried over the lingual sur- 
 face of the left central up between the central and lateral, thus making 
 the strip act as a matrix for the cavity in the distal surface of the left 
 central. The matrix can be manipulated with the fingers to suit the 
 operator and form the cement under the celluloid matrix. 
 
 If the filling is to be in a proximate surface of any of the posterior 
 teeth the celluloid can be used just as with the copper matrix for an 
 amalgam filling, only using the celluloid instead of the copper. 
 
 The cement should be mixed upon a slab made by using the surface 
 of a large flat bottle. This bottle is to be filled with water at a tem- 
 perature of about 60° F., for a cement mixed at that temperature will 
 give the best results. In case the day is too hot and humid such a 
 procedure may not be best, as the cool bottle in such an atmosphere 
 will have moisture condense upon its surface and the result be worse 
 than using a slab at room temperature. Therefore, the temperature 
 
254 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 and humidity of the atmosphere must be taken into consideration.^ 
 The siHcates are so sensitive that weather conditions may either make 
 or mar an operation. A portion of the powder should be placed on one 
 end of the slab and a portion of the liquid at the other. A small portion 
 of the powder should be incorporated in the liquid and mixed thoroughly 
 with an agate spatula. One made of any of the metals will be likely 
 to discolor the filling by the abrasion of its surface and the incorpora- 
 tion of the abraded particles into the mass of the filling. A spatula of 
 tantalum, however, may be used, for it is of such hard consistency that 
 it will suffer little abrasion and will not discolor the cement. 
 
 The mix should be of a soft putty consistency and should be thor- 
 oughly spatulated until the mass of powder is perfectly incorporated 
 in the liquid. 
 
 The instruments that are used for the insertion of the silicate 
 should be not of steel but of ivory, tortoise shell or tantalum. The 
 tantalum instruments are preferred as they are stiffer and can be 
 made of more convenient shapes and can be used with more force than 
 the others. The cement should be placed in the cavity as quickly as 
 possible and shaped to form before crystallization begins, and should 
 not be disturbed after it begins to set, for if it is the forming crystals 
 will be broken up and the best results not obtained. 
 
 After the cement has hardened it may be trimmed to form after 
 which it should be allowed to set under the protection of the rubber 
 dam for at least fifteen minutes, when it may be coated with the varnish 
 furnished by the manufacturers or by a varnish made by the solution 
 of white rosin in ether. The rubber dam may then be removed and the 
 patient dismissed. 
 
 The silicates may be used in the form of a crown for the restoration of 
 badly broken-down teeth by the use of the Caulk' s tooth forms. These 
 are hollow celluloid forms of the teeth, and are so made that when 
 the proper form is selected it may be filled with the enamel in the 
 proper shades to suit the case, making the gingival portion a little 
 yellow, the central portion of the color of the approximating teeth and, 
 if called for, shading the incisal with a little blue to simulate the enamel 
 that is without a dentin background, as is the case in long thin incisors. 
 In making these mixes at the same time it will be necessary to have an 
 assistant make one mix while the operator makes the other. 
 
 The form filled with the suitable silicate is pressed down upon the 
 prepared tooth and allowed to harden. It should be kept dry for fifteen 
 or twenty minutes and then the patient dismissed with the celluloid 
 form in position, with instructions to call the following day to have it 
 
 1 The reader is referred to Chapter VII for a further discussion of this subject. 
 
MANAGEMENT OF CHILDREN'S TEETH 255 
 
 removed and the crown polished, if necessary. If the work has been 
 done carefully there will be very little polishing necessary, for the 
 polished surface of the celluloid form will give a high polish to the 
 enamel crown. 
 
 In the same manner, broken bridge facings may be repaired with the 
 same material. In this case the forms are not entire crowns, but 
 merely the facings, which may be selected for the case and filled with 
 the suitable material and pressed to place over the pins in the backing 
 of the broken facing. When the cement has hardened the form is 
 removed, the facing coated with varnish and the patient dismissed. 
 In these and many other ways that will suggest themselves to the 
 ingenious dentist the silicates fill a large place in the practice of a busy 
 man and serve the patient very well indeed. But to reiterate, a restora- 
 tion of any kind made with a cement is not permanent if the cement is 
 exposed to the fluids of the mouth and the friction of mastication. 
 
 The oxyphosphates are valuable for all kinds of temporary work, 
 the sealing in of medicaments in root treatment, the treatment of 
 children's teeth and the setting of inlays, crowns and bridges. 
 
 The inlay regime has brought the cements into use more than ever 
 before, and protected by a perfectly fitting inlay, this makes about as 
 near the ideal restoration of broken-down tooth tissues as modern 
 science has yet attained. 
 
 For an inlay it is necessary to mix the cement a little thinner than for 
 a filling, for if the mix is made too stiff the inlay will not go to place. 
 The mix should be of a heavy cream consistency about as stifle as will 
 drop from the spatula when held up from the slab. It should be placed 
 in a dry cavity, but the modern hydraulic cements of the oxyphosphate 
 type do not need to be kept dry after the inlay is seated. The fact is 
 the makers say that it is necessary to have the addition of moisture 
 to perfect the setting. (See Chapter VII.) 
 
 For the setting of crowns and bridges the oxyphosphates are also 
 used and are found the best medium for that purpose, for their tenacity 
 is such that they add somewhat to the retention of the crown. It will 
 be found necessary to make the mix for crowns and bridges thinner 
 than for fillings, but a little stiff er than that used for the setting of the 
 inlay. 
 
 THE MANAGEMENT OF CHILDREN'S TEETH. 
 
 The first point in the management of the teeth of children should be 
 the instruction of the parents in the importance of the temporary or 
 deciduous teeth, for very few of them realize, in any degree, the 
 necessity for maintaining the deciduous teeth in any sort of health. 
 The frequent expression, "Oh! they are only first teeth and he will 
 
256 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 soon lose them," is indicative of the carelessness with which the 
 average parent views the ravages of decay in relation to the first, 
 deciduous teeth. Therefore it should be the business of the dentist 
 to institute a campaign of education among the parents of children to 
 instruct them in the importance of the deciduous teeth in relation to 
 the comfort, health and development of the child. From the manner 
 in which many dentists dismiss the subject, it is evident that they also 
 need a little enlightenment upon the subject, or at least should have 
 their conscience awakened by being taught the baneful effects upon the 
 growing child of a mouth full of diseased teeth. 
 
 In this day, when we are taught that many of the ills of the human 
 family are directly traceable to foci of infection in and about the 
 teeth, we should not overlook the fact that an abscess at the root of a 
 deciduous tooth harbors the same organisms that make the one on a 
 permanent tooth dangerous. If these organisms are dangerous to the 
 adult they are in even a larger degree dangerous to the child. Not 
 only so, but the fact that the teeth in decaying cause irritated pulps 
 with consequent pulpitis and all forms of toothache, which are as 
 painful to the child as to the adult, should make every lover of children 
 do all in his power to avert the needless suffering that is thus caused. 
 That suffering by reason of toothache is the cause of much of the ill- 
 health of childhood is an undoubted fact, for the nervous system of 
 children is easily upset and the reflex action caused by a severe and 
 long-continued attack of toothache will frequently so disturb the nerve 
 balance of the child that a severe illness and possible fatal result may 
 ensue. 
 
 The decay of the teeth causes an inability to eat properly, and the 
 child, with a mouth full of decayed teeth, either refuses food or bolts 
 it whole or very imperfectly masticates it. Food thus entering the 
 stomach of the child is not fit for digestion and the child suffers from 
 all of the ills that follow in the train of digestive disturbances. Not 
 only so, but the constant swallowing of the millions upon millions of 
 bacteria and their toxins, that are holding high carnival upon the 
 substance of the teeth, is not conducive to the health and development 
 of the child. Many an adult today is suffering from digestive disturb- 
 ances and faulty food habits that are the result of neglected conditions 
 in the deciduous teeth. 
 
 Cavities in the teeth are ideal culture mediums for all sorts of patho- 
 genic organisms, and the child who has overcome an attack of diph- 
 theria, scarlet fever or any other infectious disease becomes a carrier 
 of that disease by harboring the organism in the cavities of the teeth, 
 and then expelling them in the saliva, in expectorating, coughing or 
 sneezmg, to the detriment of all of the other children m the vicinity. 
 
MANAGEMENT OF CHILDREN'S TEETH 257 
 
 One of the strongest arguments for the compulsory exammation and 
 care of the teeth of children is this fact. The child with decayed and 
 diseased teeth is not only a menace to himself, but also to every child 
 with whom he comes in contact. It may not make very much diflfer- 
 erence to us how much the children of the poor may suffer, but when 
 we reahze the truth that they will not and do not suffer alone, but pass 
 on the germs of their misery to your child and mine, it makes us think. 
 
 The future generation will never be what it could be until the teeth 
 of the children of this generation are kept from the ravages of decay, 
 and the sooner the public realizes this truth the sooner will the world 
 enter upon a real foundation of the prevention of disease. 
 
 The first thing, then, in the treatment of children's teeth is prophy- 
 laxis, the prevention of disease. The child should be under the care of 
 the dentist as soon as the first teeth erupt, and sometimes it is necessary 
 to see them before the emergence of the teeth from the gums, for if the 
 teeth do not erupt easily the disturbances to the nervous system of the 
 child may be very serious, even to the point of bringing on convulsions. 
 If the gums are inflamed and tender and the child irritable and crosg^ 
 with every indication of painful dentition, it will be good practice to 
 lance the dense gum tissue over the erupting tooth or teeth and assist 
 nature in bringing the tooth to the surface. In doing this a very sharp 
 lancet should be used and the cut made in accordance with the needs 
 of the case. If it is an incisor a straight cut following the incisal edge 
 of the tooth will be all that is necessary. If a molar it will be wise to 
 make a cross-cut, one from the disto-lingual angle and one from the 
 disto-buccal angle, diagonally across the gum where the tooth is to 
 emerge. These two incisions will cross each other at about the point 
 of the center of the tooth and continue to the opposite angle from 
 whence they started. 
 
 It is usually only necessary to lance one or two teeth at a time, for 
 there are not more than four erupting at any one time, and there are 
 not many cases in which all are gum-bound. The relief given to the 
 child is usually almost immediate and the reflex symptoms rapidly 
 abate. 
 
 When the teeth have been erupted they should be kept clean and the 
 mother and nurse should be instructed in the importance of so doing. 
 The cleansing of the teeth with a soft cloth will do for the first few 
 months, but as soon as possible the child should be accustomed to the 
 proper use of the brush. Simply sweeping the brush over the labial and 
 buccal surfaces of the teeth will do little good and may do much harm, 
 for it gives a false sense of security to the patient. A small brush 
 should be obtained, and following the system of Dr. Charters, of Des 
 Moines, Iowa, the bristles at the heel of the brush should be cut oft' 
 17 
 
258 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 with a sharp knife, leaving a tuft of bristles at the end. In use the 
 brush should be placed at right angles to the teeth and the bristles 
 inserted between them, so that they enter the interproximate spaces, 
 and then the brush should be rotated in such a manner that the 
 bristles may scrub the approximating surfaces of the teeth, just the 
 places where the bacterial plaques first attach themselves. If these 
 surfaces are kept clean there will be no possibility of the bacteria form- 
 ing the destructive plaque, and the teeth will not decay. After the 
 teeth have been thus treated from the labial surface the brush should be 
 inserted in the embrasures from the lingual surface and the method of 
 cleansing the proximate surfaces of the teeth followed from within the 
 arch. This method cleanses the portions of the teeth that need it, 
 and in addition to that the friction of the brush upon the septal tissue 
 makes it firm, resistant and healthy. Tooth pastes and mouth washes 
 are not essential, but a bland paste of pleasant taste and a normal salt 
 mouth wash are all that are necessary.^ The child should be encouraged 
 to rinse the mouth forcibly after each meal, this to be done by holding 
 the lips together with the fingers and then forcing the wash between 
 the teeth with so much force that it would be sprayed out of the mouth 
 were not the lips held tightly together with the fingers. A pleasant 
 and efficient mouth wash may be made at home by taking one tea- 
 spoonful of salt, one of bicarbonate of soda and ten drops of the oil 
 of cassia to the pint of water; this to be brought to a boil and then 
 bottled for future use. This wash is pleasant to the taste and the 
 children usually like to use it. Also, it makes them think they are 
 using something more than water, so the psychology of its use is good. 
 
 The children should be brought to the dentist at least every six 
 months after the eruption of the teeth for a cleansing and any repara- 
 tive work that may be necessary. If this is faithfully carried out there 
 will be little danger of dental complications in childhood. In cleaning 
 the teeth a soft piece of wood should be shaped to a point and charged 
 with the flour of pumice. With this every surface of the teeth should 
 be thoroughly polished, all the time making play of it. Life to a child 
 is one big game and the dentist who can enter into the spirit of play 
 with them and make the operation a game will have little difficulty in 
 the management of children. 
 
 Incipient decay in the pits and fissures of the teeth may be treated 
 with nitrate of silver. The Howe ammonium solution is of splendid 
 service. The silver solution should be infiltrated into the defective 
 places in the teeth after having dried the tooth and protected the 
 mouth with a cotton roll or napkin. 
 
 1 The reader is referred to Chapter III for a further discussion of this subject. 
 
MANAGEMENT OF CHILDREN'S TEETH 259 
 
 After the silver solution has had a chance to soak into the fissure, 
 reduce the silver with eugenol. This will cause a deposit of metallic 
 silver within the defect and will not only sterilize the cavity but will 
 infiltrate the decayed process with metallic silver and protect it from 
 a recurrence of decay for some time at least. The process of using the 
 silver solution and reducing with eugenol should be repeated several 
 times to make the deposit as heavy as possible. In case the decay has 
 progressed so far that an appreciable cavity is in evidence the enamel 
 margins should be cut away as much as necessary and as much of the 
 decay removed as can be without pain to the patient. It is desirable 
 to cause as little pain to the patient as consistent with the preservation 
 of the teeth. This is particularly true of the first few times they 
 are operated upon. After the confidence of the child is won he will 
 bear a great deal if he is told honestly that it will hurt some. Never 
 deceive a child, for if his confidence is once destroyed it will be impos- 
 sible to do much with him. After removing as much decay as possible, 
 sterilize that remaining with the silver solution and fill with one of the 
 cements, gutta-percha or copper amalgam. 
 
 Cement in children's teeth is very valuable, in that the operator is 
 enabled to introduce it into a cavity which would not retain a metal 
 filling. By reason of its adhesiveness it will maintain itself in a shallow 
 cavity for a considerable time, and is a very valuable material with 
 which to temporize in the treatment of children. It is much better to 
 make a cement filling that will have to be made over in a few months, 
 and not hurt the child, than to make a permanent filling and destroy 
 the confidence of the child in dentists forever. 
 
 The engine should be used very sparingly indeed in the treatment of 
 children's teeth for several reasons: (1) because of the dread children 
 have for the instrument, and (2) because the use of a bur in the decidu- 
 ous teeth is dangerous in that the pulp is very close to the surface, and 
 a little injudicious cutting with a bur is likely to penetrate the pulp 
 chamber causing intense pain to the child and the loss of the pulp. The 
 cavity preparation should be nearly all made with hand instruments, 
 and inasmuch as we are not expecting the fillings to endure for a long 
 time, sufficient retention can be obtained for all practicable purposes. 
 
 Gutta-percha is also a valuable material to use in children's teeth, 
 but should not be used in proximo-occlusal cavities, for the nature of the 
 material is such that it will jam into the interproximate space under 
 mastication and cause annoyance and pain. In occlusal cavities or 
 proximate cavities which do not involve the occlusal surface its use is 
 good practice. 
 
 One of the best materials for use in children's teeth is copper amal- 
 gam. It is black in color, but in the posterior teeth of children that is 
 
260 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 of little importance. Its antiseptic qualities and the fact that it 
 does not shrink make it most valuable in filling such teeth. The 
 fact that it wears out in time is an objection to its use in the 
 permanent teeth, but it lasts long enough to be of great service in the 
 deciduous teeth. Its physical characteristics are also in its favor, for 
 its plasticity enables the operator to place it in the child's tooth quickly 
 and efHciently, 
 
 In making a proximate filling the contact point should be maintained 
 as well as in a filling for an adult, for the same reason. The packing of 
 fibrous food into the interproximate space is as much of an irritant to 
 the child as it is to an adult, and the same measures should be insti- 
 tuted to prevent it. 
 
 Unfortunately the dentist does not have control of all, nor indeed of 
 many of his little patients, and the first time that he sees most of them 
 is when they are brought to the office suffering with a toothache, and 
 in many cases frightened almost to convulsions with fear of the 
 dentist. In such cases it requires the greatest tact and patience to 
 accomplish anything for the little sufferers. The only thing that 
 should be done is to attempt to relieve the pain. In case it is a pulpitis 
 this may be done by washing out the debris as gently as possible and 
 avoiding the use of instruments except those absolutely required. The 
 food debris may be washed out with a warm solution, flavored with a 
 little oil of cassia, which will attract the attention of the child if he is 
 told that it is candy water, and he will usually learn to like it and even 
 to ask for it. If it is necessary to remove some of the decay, do it 
 carefully so as not to cause the slightest pain, and then flow into the 
 cavity a thin solution of zinc oxid in eugenol. Over this drop a thin 
 portion of an oxyphosphate cement, tamp it gently to place with a 
 moist piece of cotton and dismiss the patient. The next time be as 
 gentle as possible, all the time gaining the confidence of the little man 
 or woman and in a short time he will allow the dentist to work at will 
 with him. In cases of pulpitis that respond to treatment it may not be 
 necessary to extirpate the pulp. If the hyperemia subsides, remove as 
 much of the decay as possible without exposing the pulp, then thorough- 
 ly infiltrate with the silver eugenol solution and make a cement filling, 
 carefully watching the patient for symptoms of a dying pulp. It is 
 much better to preserve the pulp if possible, but on the first symptom 
 of its death the tooth should be opened and the pulp removed. 
 
 The extirpation of the pulp in the teeth of children is a difficult and 
 trying operation. Arsenic should not be used at all in deciduous teeth. 
 If the pulp must be devitalized, it can be accomplished by the repeated 
 application of phenol, ammonia or formocresol in cases of a putrescent 
 odor. In the removal of the pulp and the filling of the canal the same 
 
GOLD INLAY 261 
 
 asepsis should be observed as in the treatment of the adult teeth, for 
 the child is susceptible to the same organisms and may suffer the same 
 general diseases due to focal infections. If possible to place the dam 
 it should be done. But the difficulty of doing so with a child in the 
 treatment of deciduous teeth is realized. If not possible, much can 
 be accomplished with cotton rolls and the saliva ejector, the assistant 
 helping with both. 
 
 Howe's silver solution is invaluable in the treatment of the root 
 canals. The solution should be introduced into the pulp chamber and 
 allowed to penetrate the canals by capillary attraction. Much instru- 
 mentation should be avoided, for if the solution is forced past the apical 
 foramen it will cause an irritation that will be difficult to relieve. If 
 not forced through by instrumentation there is little danger, however. 
 In the teeth of children it is advisable to reduce the silver with eugenol 
 rather than use the formic acid method, because of its non-irritating 
 property. This method seals the tubuli and sterilizes them at the 
 same time, after which the canals can be filled. The filling is accom- 
 plished with Buckley's euca-percha, followed by a cone that has had 
 the end clipped off' so that it will not penetrate the foramen; the pulp 
 chamber is filled with gutta-percha and the cavity finished with a 
 cement. Later on the cavity may be filled with amalgam if desirable. 
 All deciduous teeth that have had the pulp removed and the root 
 canals filled should be watched from time to time to see that no marked 
 destruction has taken place and that the coming tooth in the permanent 
 set is erupting properly, for in many cases the roots of the deciduous 
 teeth will not be absorbed and the permanent teeth will not come into 
 their proper places in the arch as a consequence. If either happens 
 extract the deciduous tooth. It is advisable for the development of 
 the arch to retain the deciduous teeth as long as nature intended, but if 
 infection or irregularity is likely to occur as a consequence of the 
 retention of a pulpless tooth it is the part of wisdom to choose the lesser 
 of the evils and extract the offending tooth. Abscesses on deciduous 
 teeth are an indication that such teeth should invariably be removed. 
 It is not wise to take the chance of a possible systemic infection with a 
 child. 
 
 GOLD INLAY. 
 
 The preparation of a cavity for the reception of a gold inlay does 
 not differ materially from that for a gold filling. The only difference 
 is that a cavity for a gold filling may be made so that it offers some 
 internal retention in the way of undercuts, which are obviously contra- 
 indicated in making a cavity for a gold inlay, for if an undercut were 
 made, the wax pattern would not draw and, if it did, the inlay would 
 
262 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 not go to place when completed. Fundamentally, however, the prin- 
 ciples of making a cavity for a gold inlay are the same as for a gold 
 filling. Therefore, it will not be necessary to discuss the preliminary 
 observations on cavity preparation, as they have been given in the 
 article on gold fillings, to which the reader is referred. The same 
 sequence of operation and cavity classification will be followed in this 
 article. 
 
 a b 
 
 Fig. 197. — Mesio-occlusal cavity in the upper first molar: a, for gold inlay; b, for gold foil. 
 
 The principles governing the construction of a gold inlay are compre- 
 hended in the preparation of the cavity; making the model or pattern; 
 investing and burning out the pattern; casting; and cementing and 
 finishing. 
 
 Fig. 198. — Preparation of a cavity in the occlusal surface of a lower molar, and cross- 
 section thereof, showing the flat pulpal wall, the parallel axial walls and the bevel of the 
 cavo-surface angle. 
 
 Cavity Preparation. — Class I cavities are prepared with flat seats 
 and parallel walls. These cavities are those occurring in the occlusal 
 surfaces of molars and bicuspids and the buccal pits of molars and 
 lingual pits of the incisors. The buccal and lingual walls are cut out 
 
GOLD INLAY 
 
 263 
 
 with a cross-cut fissure bur, No. 702, and the pulpal wall made flat 
 with the same instrument. 
 
 The preparation of the cavo-surface angle is a little different from 
 that of a cavity for a gold filling, for the bevel is a little longer. This is 
 done for the reason that it makes a longer flange upon the inlay and for 
 
 Fig. 199. 
 
 -Occlusal cavity in lower 
 first molar. 
 
 Fig. 200. — -Occlusal cavity with ex- 
 tension in buccal groove in lower second 
 molar. 
 
 the additional reason that a short bevel on the inlay would not have as 
 great edge strength as a malleted filling, as the gold in the filling is 
 harder than the gold in an inlay. The bevel for the inlay should be 
 nearly, if not quite, the depth of the enamel and should make an angle 
 with the wall of the cavity of about 90 degrees. 
 
 Fig. 201. — Occlusal cavity in upper 
 first molar. 
 
 Fig. 202. — Occlusal cavity with exten- 
 sion in disto-lingual groove in upper second 
 molar. 
 
 There is practically no difference in the preparation of Class II 
 cavities from that for the gold filling. The steps are made flat, the 
 walls parallel and the cavo-surface angle is beveled all around. The 
 emphasis should be placed upon making the walls parallel, for the 
 retention of an inlay depends a great deal upon frictional resistance. 
 Dependence cannot be placed upon any internal retention, for that 
 
264 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 would militate against the making of an inlay, and in proportion as we 
 depart from the paralleling of the walls and make the cavity cone- 
 shaped, with the base at the occlusal and the walls converging pulpall}^, 
 we lose the frictional resistance of the walls of the cavity, and the 
 
 Fig. 203. — Mesio-occlusal upper first bicuspid. 
 
 Fig. 204. — Mesio-occlusal upper first 
 molar extending to oblique ridge. 
 
 Fig. 
 
 205. — Mesio-occlusal upper first 
 molar involving distal pit. 
 
 Fig. 206. — Mesio-occlusal lower first molar. 
 
 retentive form thereof. Retention is secured by the paralleling of the 
 walls plus depth of cavity. If the cavity is not of sufficient depth, 
 there will not be enough wall to make resistance even though it be 
 made parallel. The cavity should never be less than the thickness of 
 the enamel, and usually considerably more, depending entirely upon 
 
GOLD INLAY 265 
 
 the amount of stress the finished inlay will have to resist. All inlays 
 and fillings should be anchored in the dentin and never in the enamel. 
 If there is Httle or no occlusion it will be necessary only to clear the 
 enamel and anchor in the dentin, but if the stress is great, the cavity 
 should be cut proportionately deeper. 
 
 a b c 
 
 Fig. 207. — Mesio-occluso-distal cavity in upper first bicuspid: a, mesial view; 
 b, occlusal view; c, distal view. 
 
 Mesio-occluso-distal cavities in molars and bicuspids, while following 
 the general principles outlined, may have the mesial and distal walls 
 converge slightly, as in this class of cavities there is sufficient frictional 
 resistance offered by the great amount of wall space to afford plenty of 
 retention and the converging walls make the obtaining of the pattern 
 and the placing of the inlay a much easier matter. 
 
 Fig. 208. — -Mesio-occluso-distal cavity Fig. 209. — Mesio-occluso-distal cavity 
 
 in upper first bicuspid with buccal cusp in upper first bicuspid, both cusps cut 
 
 cut away for protection. away for protection. 
 
 If there is a weakness of the buccal or lingual walls it is advisable to 
 cut off a portion of the cusps and build the inlay over them in order to 
 prevent the fracture of either wall under stress. The inlay lends itself 
 beautifully to this class of operative procedures and many teeth that 
 
266 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 formerly would have been crowned are now restored by the inlay. In 
 some instances, where much of the dentin is gone and the pulp has been 
 removed, the inlay is anchored in the pulp chamber and a subpulpal 
 seat made for retention. 
 
 Fig. 210. — Mesio-occluso-distal cavity 
 in lower second molar with buccal cusp 
 cut away for protection. 
 
 Fig. 211. — Mesio-occluso-distal cav- 
 ity in lower first molar with lingual cusps 
 cut away for protection. 
 
 Class III cavities are approached from the lingual surface and the 
 preparation differs considerably from that for the gold filling. With a 
 fissure bur. No. 702, entrance is gained into the cavity from the lingual 
 surface and the axial wall made flat, cutting to a depth that will leave 
 a small amount of dentin between the cavity and the labial wall of 
 enamel. 
 
 Fig. 212. — Mesio-occluso-distal cavity in upper first molar with disto-lingual cusp cut 
 
 away. 
 
 The labial cavity outline need not be very great if the decay does not 
 demand it. The enamel on the labial surface should be cut only far 
 enough to cause the inlay to clear the approximating tooth, thus 
 making for a clean margin and satisfying the law of extension for 
 prevention. This is done for the purpose of hiding the gold as much 
 as possible and also allowing a seat for the inlay, which in this class 
 of cases is against the labial wall. The gingival and incisal walls 
 
GOLD INLAY 267 
 
 should be made to slope slightly away from each other, the gingival 
 one sloping apically and the incisal one incisally, thus causing them to 
 diverge as they approach the axial wall. This will make a dovetail 
 in the preparation that will prevent any lateral displacement and will 
 allow the inlay to be inserted from the lingual and from no other direc- 
 tion. The cavo-surface angle should be beveled all around, but it is 
 obvious that there can be no real bevel made upon the labial margin 
 or the wax would not draw. Fortunately, we find that the lay of the 
 enamel rods in this position is such that a straight cut through the 
 tooth from labial to lingual will leave no short rods upon the surface, 
 for the natural curve of the tooth is such that as the rods bend over in 
 conformity to the shape of the tooth they are cut in such a way that 
 all rods reaching the surface are those that have their base in contact 
 
 a be 
 
 Fig. 213. — a. cavity for inlay in upper central incisor, lingual aspect; b, same 
 cavity, labial view; c, same cavity, proximate view. 
 
 with the dentin. Therefore a straight cut through from lingual to 
 labial is to all intents and purposes a bevel and a flange will be cast 
 upon the inlay to perfect contact with the enamel. The approaching 
 of the cavity from the lingual surface in the upper incisors affords 
 additional security in that the stress of occlusion comes from the 
 lingual surface as the lower teeth impinge upon the upper from that 
 direction, which serves to pound the inlay into the cavity, and there is 
 little danger of its displacement. In the lower incisors this is not true. 
 Nevertheless, we approach the cavity from the lingual, for the labial 
 approach is of such bad esthetic form that it is absolutely contra- 
 indicated. If the incisal angle is not involved there is little danger of 
 the incisal stress displacing an inlay in a lower incisor that is made 
 from the lingual, for there is really no stress that reaches the inla}'; but 
 if the incisal angle is involved it will be necessary to obtain additional 
 
268 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 retention by making an incisal step cavity and a sufficiently deep 
 incisal anchorage. 
 
 In Class IV cavities we again depart considerably from the conven- 
 tional gold-foil preparation on account of the difference in retentive 
 problems. 
 
 There are two methods of obtaining retention in this class of cavities : 
 one, the incisal step and the other the lingual dovetail cavity. 
 
 In making the incisal step cavity a portion of the incisal surface of 
 the tooth is ground down with a carborundum stone, as for a gold foil 
 operation, and the outline form obtained on the labial surface in the 
 same manner; but the outline form on the lingual surface is different 
 from that used in the foil preparation by reason of the fact that the 
 
 Fig. 215 Fig. 216 
 
 Figs. 214, 215 and 216. — Mesio-incisal cavity in upper central: Fig. 214, labial view; 
 Fig. 215, incisal view; Fig. 216, lingual view. 
 
 internal preparation demands a treatment that makes the outline form 
 on the lingual surface of different shape. The form of an incisor or 
 cuspid is wedge-shaped or conical; therefore, the treatment of the 
 lingual and labial walls takes on the laws governing conic sections. 
 We know that parallel lines must leave the cone at some point and the 
 farther apart are the lines the sooner will they leave the cone in their 
 progress toward the apex thereof. We cannot make the internal prepa- 
 ration of the cavity in such a way that there will be any undercuts 
 or retention that will not permit the wax to draw, therefore the 
 walls are made parallel, as far as the shape of the tooth will 
 permit. But as the lines must leave the tooth at some place we 
 choose to make the walls parallel at the labial contour of the tooth, 
 as then the labial line does not leave the tooth at all but travels along 
 
GOLD INLAY 
 
 269 
 
 the long axis of the tooth until it reaches the ineisal angle. Therefore, 
 the wall along the lingual aspect will of necessity leave the tooth sooner 
 than it otherwise would, and it does so at about the beginning of the 
 middle third of the tooth. This method of preparation is chosen for 
 esthetic reasons, for if the line at the labial were allowed to leave the 
 tooth at any portion thereof it would make a very unsightly appearance 
 in the labial outline form. Inasmuch as the wall at the lingual leaves 
 the tooth at the middle third there is very little retention due to the 
 parallel walls, and it is necessary to obtain some additional retention. 
 This is done by cutting a pit in the pulpal wall of the preparation after 
 the cavity passes the lines of pulpal recession, for to cut a pit at the 
 line of recession would endanger the pulp. The cavo-surface angle is 
 beveled all around as in any other cavity. 
 
 Fig. 217 Fig. 218 
 
 Figs. 217 and 218. — Mesio-incisal cavity in upper central incision. Fig. 217, lingual 
 view. Fig. 218, labial view. 
 
 The lingual dovetail preparation is made by approaching the cavity 
 from the lingual surface as in a simple Class III cavity, but as the ineisal 
 angle has been destroyed by the progress of decay, additional retention 
 is necessary. This is obtained in the lingual dovetail preparation by 
 making the cavity as nearly retentive as possible, following the method 
 of the simple Class III preparation and then cutting an additional dove- 
 tail in the lingual surface of the tooth. The stress of mastication on 
 an upper incisor tends to drive the inlay farther into the cavity rather 
 than out of it, and this makes this preparation of particular value. It is 
 necessary to be very careful not to expose the pulp in the preparation 
 of the lingual dovetail, as there is danger of doing if the cavity at this 
 point is made too deep. It is only necessary to cut the dovetail through 
 
270 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 the enamel and anchor well into the dentin. If this is done there is no 
 danger of pulpal complications. If it is thought necessary to make a 
 deeper preparation for the lingual dovetail by reason of extreme stress 
 
 Fig. 219 Fig. 220 
 
 Figs. 219 and 220. — Disto-incisal cavity in upper cuspid. Fig. 219, labial view. Fig. 
 220, lingual view showing lingual dovetail. 
 
 or abnormal occlusion in the region opposite the proximate surface in 
 which the cavity is located, sink the dovetail deeper into the dentin. 
 This will give a preparation that will make a thinner mass of gold as 
 
 Fig. 221 Fig. 222 
 
 Figs. 22 1 and 222. — Mesio-inciso-distal cavity in upper central incisor, 
 
 it passes over the pulpal area, but will be deeper and heavier and sink 
 farther into the dentin when in safe territory. The cavo-surface angle 
 is beveled all around this cavity as well, observing the rule on the labial 
 
GOLD INLAY ■ 271 
 
 surface that obtains in the preparation of the cavo-surface angle in 
 Class III cavities. 
 
 This preparation provides a, restoration that is much more esthetic 
 than the incisal step cavity, and one that is fully as likely to maintain 
 itself against the stress of mastication and wear. 
 
 The same rules apply to cavities in the lower incisors and cuspids, but 
 owing to their diminutive size the preparation is more difficult and calls 
 for a larger degree of patience and skill to accomplish the desired result. 
 
 Class V cavities occurring in the gingival thirds of any of the teeth 
 are treated much the same as like cavities in the gold-filling series. The 
 outline forms and the axial walls are the same, the only difference being 
 in the preparation of the mesial, distal, gingival and occlusal walls. 
 These will not admit of any undercuts and must be made as nearly 
 parallel as the skill of the operator will permit. The departure from 
 the parallel walls will proportionately make for a lack of retention, and 
 while there is practically no stress that falls upon inlays in this position, 
 it is a fact that if there is not sufficient retention these inlays will fall 
 out. The saucer preparation is decidedly contra-indicated in making 
 a gold inlay. The cavo-surface angle is beveled all around the cavity. 
 
 Making the Pattern. — Any good wax that is hard at mouth tempera- 
 ture and perfectly disappears under the amount of heat to which it is 
 thought desirable to submit the investment may be used. It is pref- 
 erable to use one that is hard at mouth temperature, as all of the steps 
 of making the pattern, investing, etc., should be carried out at the same 
 temperature, and if a wax were used that was so soft that it required 
 a dash of cold water to harden it, it would shrink so much that a good 
 pattern would not be obtained. Heat expands and cold contracts; 
 therefore if the pattern is to be a perfect reproduction of the cavity 
 it must be handled at as nearly the same temperature throughout the 
 operation as it is possible to do. 
 
 The wax may be warmed in any way that is convenient but should 
 not be melted in the warming. If softened over a flame it should be 
 held high enough above the heat so that it softens slowly and should 
 be constantly turned and watched to see that it does not melt. After 
 a little trial the color of the wax will be the index to the eye of the 
 operator of the degree of softness. 
 
 The wax may also be softened in warm water of about 130° F. A 
 convenient way to do this is to obtain a large flat cork and thrust a 
 number of pins through the cork. Upon these pins, portions of the 
 wax may be impaled and the cork then inverted in a glass of water of 
 the proper temperature. In a short time the wax will be of the right 
 consistency to use. Dr. Taggart has invented a very valuable instru- 
 ment which is designed to keep the wax at the proper temperature. 
 
272 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 The wax should be drawn to an elongated cone, the apex of which is 
 slightly softened a little more than the rest of the wax by holding it for 
 a moment over a flame: this for the purpose of making a softer 
 portion of wax to be inserted into the cavity and the harder part to act 
 as a piston to force the wax mto every part of the cavity. Pressure should 
 
 Fig. 223. — Taggart automatic heater for casting wax. 
 
 be made upon the wax from every direction and maintained until the 
 wax is hard. This pressure is obtained by using the index finger and 
 thumb of the left hand on the lingual and buccal sides of the tooth if a 
 molar or bicuspid, and on the lingual and labial if an incisor or cuspid. 
 This forms a matrix into which the wax is forced by the pressure of the 
 
GOLD INLAY 273 
 
 index finger or thumb of the right hand as it presses the wax into the 
 cavity. This pressure is necessary as the wax shrinks in hardening 
 and as the pressure is maintained more wax is forced into the cavity 
 to take the place of the shrunken portions, thus obviating a discrepancy 
 and a more nearly perfect reproduction of the cavity is obtained. After 
 the wax has hardened it may be carved to form. It is not advisable 
 to allow the patient to bite into the wax to obtain the occlusion, for the 
 wax has now hardened and biting into it will disturb the adaptation. 
 The pattern should be carved to occlusion and anatomic form. The 
 patient may try the occlusion very easily from time to time if thought 
 desirable, but the skillful operator will not need much of that, for he 
 will know his dental anatomy so well that if there is no abnormal occlu- 
 sion he will have very little difficulty in carving to form and occlusion. 
 If there is an abnormality of occlusion, or if for any other reason the 
 operator desires to obtain the direct occlusion of the opposing teeth, 
 he may do so by warming slightly the occlusal surface of the wax with 
 a warm ball burnisher or the hot-air syringe, then allowing the patient 
 to bite into the warm wax. The body of the wax being hard and the 
 surface soft there will be no danger of the distortion of the pattern. 
 One of the best instruments to use in carving the proximate surface of 
 the pattern, and especially that portion near the gingival margin, is a 
 large sickle-shaped exploring instrument, the fine prong of which can be 
 inserted into the interproximate space and the wax carved out at will. 
 It is also convenient in obtaining the adaptation at the gingival below 
 the free margin of the gum and cutting off any overhanging wax. The 
 occlusal surface should be carved to anatomic form, being careful to 
 restore the marginal ridge. The inlay lends itself beautifully to the 
 artistic reproduction of all of the markings of the tooth, and an impres- 
 sion taken of the tooth after the inlay is in place should look as though 
 it were the perfect tooth instead of a restoration thereof. 
 
 When the carving is finished the whole pattern should be washed 
 with the oil of cajuput, which will smooth the surface by slightly dis- 
 solving a film of the wax. 
 
 In removing the model a sprue wire of the proper size may be warmed 
 and allowed to melt its way into the pattern and kept there until it is 
 perfectly cool and the wax around it has hardened, when the pattern 
 may be lifted out of the cavity very easily. Or if a curved explorer be 
 used the point should be inserted into the inlay about where the contact 
 should be and the pattern carefully lifted out. Force should never be 
 used in dislodging the pattern, for to do so will endanger the perfection 
 of the impression. A slight distortion will spoil the entire operation. 
 
 If the model has been made for a proximo-occlusal cavity it is mse to 
 take a shaving of the wax where it comes in contact with the occlusal 
 18 
 
274 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 step. In the preparations it will be noticed that there are no shelves 
 in the cavity on which the inlay may ride, and all of the lines of the 
 preparation flow into the cavity, so that if the inlay did not reach the 
 gingival portion of the cavity through some slight shrinkage of the wax 
 or gold it would sink down into the cavity until it rested on the gingival 
 seat if it were not for the occlusal step. Therefore, the relieving of the 
 wax at that point will allow any descrepancy at the gingival to be 
 corrected by the inlay seating a little deeper into the cavity, thereby 
 making a perfect adaptation at all of the margins. 
 
 Fig. 224. — Position of hands while inserting warmed sprue into wax pattern after it has 
 been removed on an explorer. 
 
 The pattern should be invested as soon as removed from the tooth 
 to prevent any movement of the wax through any change of tempera- 
 ture that it might encounter in lying around the office waiting for the 
 investment. The pattern should be washed with a soft camel's hair 
 brush, using peroxide of hydrogen, alcohol or soap and water — to 
 remove any oily or muciferous materials from its surface so that the 
 investing material will more easily adapt itself to the wax. The 
 water in which the investing compound is mixed should be the 
 same temperature as that used to cool the wax while carving to avoid 
 a change in the volume of the wax. 
 
 Fig. 225. — Taggart measuring device for investing material and water; large end for 
 investing material, small end for water. 
 
 Any good investing compound may be used, or the operator may 
 make one himself that is very satisfactory by taking 3 parts by measure 
 of finely pulverized silex to 1 part of plaster of Paris, This should be 
 
GOLD INLAY 
 
 275 
 
 thoroughly mixed together. It may be mixed by taking an ordinary 
 flour-sifter, such as housekeepers use in making bread, and sifting the 
 mix through this three or four times, when a homogeneous mass will 
 
 Fig. 226. — Position of plaster bowl while it is being revolved and jolted on the bench. 
 
 Fig. 227. — Taggart automatic mixing device for investing material and water. 
 
 be obtained. A balance or some kind of measuring device should 
 always be used so that the proper proportions of the investing material 
 and water may be used each time. The mix should be thoroughly 
 
276 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 spatulated and then the bowl turned around and around, at the same 
 time jolting it on the bench to cause the bubbles in the mix to rise to 
 
 Fig. 228. — Automatic mixer for investing material and water attached to ordinary 
 laboratory lathe. (Suggested by Taggart.) 
 
 Fig. 229. — Taggart's crucible former with sprue inserted into the wax and into crucible 
 former ready for investing. 
 
 Fig. 230. — Inlay covered with investing 
 material previous to placing ring on cruci- 
 ble former. 
 
 Fig. 231. — Casting ring filled with 
 hardened investing material, and cru- 
 cible former and sprue removed. 
 
BURNIXG OUT OF THE PATTERN 277 
 
 the surface and break, thus obviating, to a great extent, the danger of 
 bubbles upon the pattern, with a consequent ball of gold cast on the 
 inlay where the bubble appeared on the pattern (Figs. 226, 227 and 228) . 
 The pattern on its sprue is placed in a crucible former supplied with the 
 casting machine used and the investing compound is painted upon the 
 sui'face (Figs. 229, 230 and 231). Great care should be used to see that 
 the investing compomid is evenly and thoroughly adapted to every 
 surface and inequality of the pattern, repeatedly blowing the invest- 
 ment off of the pattern and repainting, to be sure there are no air 
 bubbles adhering to its surface. The flask should be inverted, placed 
 on a piece of paper and filled vdih the compound, and the pattern as it 
 is painted with the investing material should be slowly inserted into 
 the mass, all the time vibrating the pattern as it sinks into the in- 
 vestment, to clear it of any air that might attach to its surface. 
 The investment should be allowed to harden, but not remam too long 
 before the burning out is begmi. 
 
 THE BURNING OUT OF THE PATTERN. 
 
 One of the most important parts of the entire operation is that of 
 bmiiing out the wax. It is necessary to dissipate the pattern in order 
 to make the mold for the reception of the gold, but too great a degree 
 of heat vnll disintegrate the plaster and cause a distortion of the 
 finished inlay. ]More misfits are caused by the injudicious use of heat 
 in the bm-ning out of the wax than any other cause. A flame should 
 never touch the investing material or flask and the temperature should 
 never rise above 320° F. "\Mien the wax is dissipated, allow the flasks 
 to cool perfect!}' and cast cold (Fig. 232). 
 
 In casting gold into a mold as small as one must be in order to make 
 an inlay for a human tooth it is necessary to use some force in order to 
 cause the metal to flow into the mold. It is also necessary to resort 
 to some method m making the model that is a departure from the usual 
 method of making molds, that is, the method of using separable flasks 
 and making the mold in these flasks, then separating the flask and 
 removing the model, then replace the separate parts of the flask in 
 immediate contact and cast. In the case of an article as small as the 
 inlay, and one that requues the exactness of duplication, the separable 
 flask is out of the question; therefore use is made of the principle of 
 the disappearing model. The model should be made of a material that 
 would disappear under the influence of heat and then mto the mold so 
 made the melted metal is forced. There are a number of devices for 
 casting the inlay. The first to be considered is the Taggart machme 
 (Fig. 233). This is automatic in action and consists of a stand for the 
 
278 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 reception of a nitrous oxid gas cylinder, which is used for the purpose 
 of making the oxyhydrogen flame to be used in melting the gold and 
 also for the purpose of making pressure with which to force the gold into 
 the mold. On the same base is located the receptacle for the flask 
 containing the mold. This seat for the flask is immediately under a 
 movable disk which is actuated by a lever which forces it down upon 
 the flask, completely closing it. When the lever closes, the flask also 
 automatically throws the blowpipe away from the crucible contained 
 
 Fig. 232. — Taggart automatic gas apparatus for burning out the wax.^ 
 
 in the upper part of the flask in which the gold is melted, and releases 
 the gas from the cylinder, which by its pressure immediately forces 
 the molten gold into the flask, thereby filling the mold with gold and 
 completing the operation of casting. 
 
 The advantage of the Taggart machine is its automatic action, and 
 having all the operations of casting, such as the blowpipe, release of 
 
 1 Several electric devices have been designed for burning out the wax, but none seem 
 to have been developed to a greater accuracy than the gas device. 
 
BURNING OUT OF THE PATTERN 
 
 279 
 
 19 - 17 15 
 
 Fig. 233. — Taggart casting appliance. 
 
 Fig. 234. — Monson's centrifugal casting machine. 
 
280 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 the pressure principle, etc., in the same machine, the art of casting is 
 quite simple. Besides, it enables the operator to retain pressure upon 
 the casting as long as necessary, a very essential part of the casting 
 principle. 
 
 Another very effective method is the centrifugal one (Fig. 234). 
 This method takes advantage of the force that causes all matter to fly 
 off at a tangent when revolved. The machine consists of an arm that 
 revolves around a central base of some kind; the arm is actuated by 
 a spring or geared wheel, which on being turned rapidly causes the arm 
 to revolve. At the end of the arm is placed a receptacle for the flask. 
 The gold may be melted in a crucible in the top of the flask, as in some 
 machines, or it may be melted in a crucible placed in front of the 
 orifice of the flask. In either case, when the gold is melted and the 
 machine actuated, as the flask begins to revolve the gold is thrown into 
 the flask and held there by centrifugal force. This method of casting 
 is very popular and beautiful results are obtained by its use. Its 
 advantages are simplicity of operation, possibility of retaining pressure, 
 and in the machines that have a crucible away from the flask itself, 
 the possibility of melting the gold without heating the flask or invest- 
 ment — a very desirable feature. 
 
 The suction method is an adaptation of the air-pressure principle, 
 but instead of using direct pressure, atmospheric pressure is used, by 
 exhausting the air in the flask and thereby causing the pressure of the 
 atmosphere to force the gold into the mold. The machine consists 
 of a vacuum chamber, from which the air is exhausted by an air pump, 
 a table upon which the flask rests, which is connected to the vacuum 
 chamber by a pipe to which is attached an air valve, which releases the 
 vacuum when desired. The flask must rest upon the vacuum table 
 with a contact that is perfectly air tight, or the vacuum will not be 
 communicated to the flask but will be dissipated by the entrance of 
 air through the leak between the table and flask. This method is 
 popular with some operators and good results are obtained with it, but 
 it is not so convenient nor simple as either of the other methods. 
 
 There are several crude methods that are used with home-made 
 machines, using the principle of steam and mechanical pressure. The 
 steam-pressure method consists of heating the gold in a crucible in the 
 flask and when melted forcing a wet asbestos pad on the flask, which 
 seals it, and, by the action of the heat contained in the melted gold, 
 produces steam which forces the gold into the mold. This method is 
 very uncertain and the same amount of pressure is never obtained at 
 two consecutive castings, owing to the difference of heat and the 
 amount of moisture contained on the pad. At best it is an unreliable 
 method. The mechanical pressure method consists of making a pad of 
 
FINISHING THE INLAY 281 
 
 molding, and upon the gold being melted the pad is forced into the 
 crucible, when it seals the top of the flask and then by reason of its 
 softness is forced deeper into the crucible and the gold is forced into the 
 mold. This method is the least desirable of any and should not be 
 used, if possible to make use of any other. 
 
 When it is said to cast cold it is meant to cast cold and not to heat up 
 the flask to a red heat in making the cast, as is the habit of some. 
 The flask should be so cool after the cast is made that it can be picked 
 up immediately in the fingers. In order to accomplish this a blowpipe 
 must be used and the small flame directed upon the gold nugget and 
 not allowed to touch any part of the flask or investment compound. 
 If a centrifugal machine is used the gold can be fused in a crucible 
 away from the flask in some machines, and when melted the spring is 
 released and the molten gold thrown into the cold flask. Pressure 
 should be maintained for at least one minute in order to force additional 
 gold into the mold as the fused gold takes on the solid state. Experi- 
 ments conducted by Dr. Weston A. Price have appeared to demon- 
 strate that up to a certain point additional gold will flow into the 
 freezing mass, thereby reducing shrinkage to the minimum. The 
 breaking away of the sprue from the inlay and the pitting of the inlay 
 at or near the insertion of the sprue wire are sure indications that 
 pressure has not been maintained sufficiently long to allow the 
 compensation of additional fused gold to the freezing mass. 
 
 The inlay should be allowed to cool slowly before the flask is opened. 
 When cold remove the inlay, wash and pickle in hydrofluoric acid, 
 boil in hydrochloric acid or heat and drop into a 50 per cent, solution 
 of sulphuric acid, and the inlay is ready for finishing. 
 
 FINISHING THE INLAY. 
 
 The inlay should be partially finished before it is tried in the cavity. 
 If the model or pattern has been well made there will be little finishing 
 to be done, as the casting will be like the pattern. The sprue should 
 be cut off and the sanded finish smoothed with a disk; then it should be 
 placed in the cavity and malleted to place. If it does not go to place 
 perfectly it should be removed and search made for any bubble or fault 
 in the investment that might militate against its perfect adaptation 
 to the walls of the cavity. When perfectly adapted it should be 
 burnished toward the walls all around the cavity, in order to make sure 
 that the adaptation is perfect. An inlay that is not perfect will save 
 the tooth for a time because the cement will fill up the defect, but the 
 operator who depends upon a bruised reed of that kind for the security 
 of his operations will surely come to grief. An inlay that shows a 
 
282 CAVITY PREPARATION AND THE FILLING OF TEETH 
 
 discrepancy at any margin should be discarded and a new one made. 
 The entire inlay may now be disked, always running the disk toward 
 the margin of the cavity and never away from it. In this way the gold 
 is flowed toward the margin and a more perfect adaptation is obtained. 
 If the inlay is worth using the margins should be so tight that they are 
 not discernible to the naked eye. If so the adaptation is so good that 
 with the sealing virtue of the cement the inlay will save the tooth as 
 long as the patient will need it, as far as any infiltration decay is con- 
 cerned. 
 
 Wheii this adaptation is secured the inlay should be removed aad the 
 tooth made ready for cementation. (See also Chapter V.) The ideal 
 method is to place the rubber dam and dry the tooth with warm air 
 supplemented by a bath of alcohol or chloroform. But most operators 
 and patients object to the use of the dam for so short an operation, and 
 the use of cotton rolls and the saliva ejector will keep the cavity dry 
 sufficiently long to enable the operator to dry and disinfect the cavity- 
 and place the inlay. If so the cement slab with the proper portions 
 of cement should be on the bracket ready for use, the cavity should be 
 washed out with a strong dash of warm water from a good water syringe 
 and the cotton rolls immediately placed in position. The tooth should 
 be dried and washed out with alcohol or chloroform, again thoroughly 
 dried with the hot-air syringe and the cement mixed to a creamy con- 
 sistency. By a creamy consistency is meant a mix that will drop off of 
 the spatula rather easily and yet will follow the instrument for some 
 little distance as it is lifted in the air. If the mix is too thick the inlay 
 will not go into place, and if too thin the cement will not have sufficient 
 body to make a good cementation medium. The cavity should be filled 
 with cement, care being used to see that all of the margins of the same 
 are covered. Many failures have been noted on account of not 
 perfectly filling the cavity with cement, thereby making a discrepancy 
 between the inlay and tooth at some point, which later on will start 
 an infiltration decay. If the inlay is well made this is about the oiily 
 possibility for infiltration decay, for if the cement has been well adapted 
 and protected by the inlay there is no possibility of a percolation of the 
 fluids of the mouth between the inlay and dentin. If there is to be any 
 further burnishing it must be done while the cement is soft and before 
 it begins to crystalize, but there should be no necessity for burnishing 
 at this time; the burnishing that might have been necessary should 
 have been done when the inlay was tried in the cavity. After the 
 cement has set, either at this time or at some future engagement, the 
 inlay may be polished with sandpaper disks, rubber and pumice. 
 The amount of polish that may be given is at the discretion of the 
 operator, but better results are obtained by a finish that is not too high, 
 
INDIRECT METHOD OF MAKING GOLD INLAYS 283 
 
 for too great a polish will so reflect the light that the gold will look 
 black in some lights. Be sure that there is no cement under the free 
 margin of the gums or between the teeth, wash out all cement particles 
 and dismiss the patient. 
 
 INDIRECT METHOD OF MAKING GOLD INLAYS. 
 
 The reader is referred to Chapter VI for a description of this 
 process. 
 
CHAPTER V. 
 GOLD INLAYS AS BRIDGE ATTACHMENTS. 
 By MARCUS L. WARD, D.D.Sc. 
 
 This chapter is written as a short supplement to Chapter IV, in 
 order to fill what appeared to some of my colleagues a void in the 
 presentation of modern operative dentistry. 
 
 During very recent years, with the development of better technic 
 for the construction of cast gold inlays, there has been a quite general 
 use of the gold inlay as a bridge attachment which has brought a new 
 branch of work from the field of bridge-work into operative dentistry. 
 With the rapid recognition of the many advantages of the inlay form 
 of attachment for bridge-work it appears likely there will be an even 
 more general use of the gold inlay, thereby bringing the subjects of 
 crown and bridge-work, and what has formerly been designated as 
 operative dentistry, into such close relationship that it will be difficult 
 to distinguish one from the other. It is this probability that makes 
 the presentation of the subject of gold inlays appear incomplete 
 without some reference to their use as bridge attachments. It does 
 not seem advisable to enter into a discussion of the subject of bridge- 
 work in this chapter, for that would involve a discussion of many 
 problems that are at the present time properly assigned to books on 
 bridge- work. It is rather to enlarge upon the statements made by the 
 authors of Chapter IV with respect to the advantages of the gold inlay 
 than to enter into a discussion of the subject of bridge-work. This is 
 particularly true regarding the amount of stress that a gold inlay will 
 resist without dislodgment. 
 
 It has been pointed out in Chapter IV that all fillings, gold inlays 
 included, should have as nearly parallel walls as possible, and flat 
 seatings in order to best resist the stress of mastication. This is 
 unquestionably the most rational practice to pursue with every form of 
 filling except possibly the gold inlay. Inasmuch as many operators 
 have found it more advantageous to deviate from this form of cavity 
 preparation in some cases, there has developed a group of operators 
 who believe that the cavity for the gold inlay does not necessarily need 
 parallel walls for retention. Not only do they believe that parallel 
 walls are not always necessary for the single inlay, but they believe 
 ( 284 ) 
 
GOLD INLAYS AS BRIDGE ATTACHMENTS 
 
 285 
 
 that quite extensive fixed bridges may be attached to them without 
 dislodgment, provided certain precautions have been taken to resist 
 stress from certain directions. There is practically a unanimity of 
 opinion on the technic of construction of the gold inlay, except the 
 necessity for parallel walls, and the reader is referred to Chapter IV 
 
 Fig. 235 
 
 for this discussion. This chapter, therefore, will be devoted to a brief 
 consideration of tapered walled cavities for gold inlays and their use 
 in the construction of inlay attachments for bridge-work. 
 
 Fig. 236 shows a tooth and cavity which represent approximately 
 the form of cavity preparation that the author used for gold inlays 
 during the years just preceding and those immediately following the 
 
 Fig. 236 
 
 introduction of the cast gold inlay in 1907. The length of the bevel 
 shown at B was varied, as necessity seemed to demand in order that the 
 requirements of acceptable cavity formation might be met. Bucco- 
 lingual extensions, as well as cervical extensions, were also varied wdth 
 the susceptibility or immunity of the case in hand. Likewise the depth 
 
286 
 
 GOLD INLAYS AS BRIDGE ATTACHMENTS 
 
 of the occlusal portion of the cavity was varied with the stress likely 
 to be applied, especially at the proximo-occlusal margin. 
 
 In October, 1908, on assuming charge of the inlay clinics at the 
 University, an investigation was made with a view of improving 
 the technic of making cast gold inlays which were receiving general 
 attention. Many of the casts made at that time did not fit, some for 
 one reason and some for another. Oftentimes it seemed impossible to 
 get certain casts near to an acceptable fit of the cavity notwithstanding 
 that much effort had been made to obtain one. It was noted that 
 mesio-occluso-distal cavities were the most difficult to manage, the 
 greatest defect appearing at the cervical portion of the inlay. Many 
 other operators made the same observation. One large dental society 
 had one of the profession's distinguished men give a clinic a second 
 time to show how to remedy the defect observed by the use of crystal 
 gold. The defect observed at the cervical portion of the casting was 
 
 Fig. 237 
 
 large enough so that an explorer could be passed between the casting 
 and the cervical wall of the cavity, and could be seen with the naked 
 eye in ordinary light. Many dentists and a few investigators attrib- 
 uted this defect to the shrinkage of the gold. Others, however, knew 
 that the shrinkage of gold on a piece of the size of an M O D inlay in a 
 molar could not be seen with the naked eye as readily as the observed 
 defect could, and proceeded to investigate other parts of the technic 
 with the thought in mind that perhaps the form of the cavity was a 
 factor of importance. The author was one of the latter and had made 
 some hard metal molar teeth with cavities in them on the same plan 
 as those shown in Figs. 235, 236 and 237 and several forms from which 
 wax patterns could be made. The hardness of the metal teeth and the 
 metal forms made bright spots on the castings at the places of contact 
 when a little pressure was applied to the castings. In the MOD 
 casting the bright spot occurred first at points A and B (Fig. 237). 
 
GOLD INLAYS AS BRIDGE ATTACHMENTS 287 
 
 As the pressure was applied to the occlusal part of the casting it 
 continued to bulge out at the cervical part C and D until there was a 
 space between the casting and cavity that would allow the passage of 
 an ordinary explorer with ease. At this time it was observed that the 
 casting had not become seated at the occlusal part E, which led to the 
 belief that the shape of the cavity had much to do with the production 
 of the defect so generally observed at the points C and D, for the casting 
 had been brightened by the metal tooth at points A and B and at no 
 others. 
 
 Cavities were then made in metal forms to correspond to the cavities 
 shown in Figs. 235 and 236 from which castings were made. Careful 
 inspection showed no particular place on the castings made for the 
 occlusal cavity (Fig. 235), which seemed to come in contact with the 
 tooth before other places did. They seemed to go to place without 
 pressure and without any fitting. The castings made for the cavity 
 shown in Fig. 236 almost always had a bright place on them at A 
 when pressure was applied. When the bright spot was removed by 
 grinding these castings would go to place without force. The conclu- 
 sion drawn was that the angle formed by the axial and occlusal v/alls of 
 the cavity at A was reproduced in the investing material and was not 
 strong enough to resist the force of the gold when it was thrown into 
 the mold. In other words, it appeared that there had been a slight 
 compression of the investing material at the point A, resulting in a 
 little too much gold in the casting. Work was then taken up on the 
 MOD cavity (Fig. 237) in connection with the M O cavity (Fig. 236). 
 In both cases the angles A, Fig. 236, and A and5. Fig. 237, were removed, 
 making a distinctly flat surface instead of an approximate right angle. 
 Castings made for these improved cavities showed that our conclusions 
 were right. There had been a compression of the investing material 
 at this attenuated point. The bright line did not appear at A, Fig. 236, 
 when pressure was applied and these castings went to place almost as 
 well as those made for the occlusal cavity, Fig. 235. The castings 
 made for the MOD cavity did not go to place so well as did those for 
 the occlusal and mesio-occlusal cavities. The bright line that had 
 previously appeared at A and B, Fig. 237, now appeared slightly nearer 
 to the cervical portion of the casting. This led to the conclusion that 
 the gold had shrunk, and that shrinkage prevented placing the casting 
 over the septum of dentin between the mesial and distal portions of the 
 tooth. This presented an entirely different problem than was presented 
 in the compression of the attenuated part of investing material. In 
 neither the mesio-occlusal nor the occlusal cavity had it been necessary 
 to construct a casting that would go over the septum of dentin which 
 separated the mesial and distal portions. As we ground away the 
 
288 
 
 GOLD INLAYS AS BRIDGE ATTACHMENTS 
 
 mesial and distal axial walls of the cavity at A and B, and toward the 
 cervical, these castings did not bulge out at C and D as before. From 
 this it appeared that a problem in cavity preparation was presented in 
 the MOD cavity that did not exist in any others. It was evident 
 that a casting which had shortened in a mesio-distal direction in the 
 slightest degree would not go to place until ?t had been stretched. This 
 
 Fig. 238 
 
 deduction led to the adoption of tapered axial walls and the production 
 of other metal teeth (Figs. 238, 239 and 240), with one incline from the 
 seat of the cavity to the margins instead of the two inclines that we had 
 used previously, and which are shown in Figs. 235, 236 and 237. This 
 was done on the basis of first being able to get a wax pattern that was 
 more accurate, and second, and equally important, to stretch the gold 
 
 Fig. 239 
 
 Fig. 240 
 
 better with a cone-shaped septum of dentin than with a septum which 
 had parallel walls. The results with this form of cavity were very 
 gratifying. The castings before they were fitted did not go to place. 
 With the gradual taper that was given to the axial walls, however, 
 only a little pressure was necessary to force castings of pure gold to 
 place. In fact, these castings were forced to place so easily that one 
 
GOLD INLAYS AS BRIDGE ATTACHMENTS 
 
 289 
 
 was hardly conscious of having exerted any pressure. When other 
 materials were used for these castings much more difficulty was 
 encountered in fitting excellent castings. Such materials as dark 22 
 carat gold, clasp metal, etc., required repeated annealings and an equal 
 number of applications of pressure in order to get them to fit as accu- 
 rately as the pure gold ones did with little pressure. 
 
 The fact that the alloys of gold did not go to place as easily as the 
 pure gold castings led many to believe that greater shrinkage had 
 taken place when the former rather than the latter were used. While 
 it is possible that future research may demonstrate a greater coefficient 
 of volume change for the alloys of gold than for pure gold, it has not 
 been done, and, as a result, we are left with only one explanation for 
 
 . 
 
 1 J" 
 
 Fig. 241 
 
 Fig. 242 
 
 Fig. 243 
 
 the greater ease with which the pure gold castings are fitted, namely, 
 they stretch easily. The ease with which pure gold may be stretched 
 may be shown by the use of a hardened steel cone such as is shown in 
 Figs. 241 to 244 inclusive. Fig. 241 shows a receptacle for the forma- 
 tion of a wax washer and a paralleling device for the removal of the wax 
 without distorting it. Fig. 242 shows the device partially opened with 
 the wax lifted from its seat and not touching the steel cone. Fig. 243 
 shows the device with the wax trimmer placed over the cone for the 
 purpose of making the wax washer perfectly flat on the top and of the 
 same thickness all around. The steel cone is three inches high and 
 0.03 of an inch smaller at the top than the bottom which is 0.250 of an 
 inch, and is as nearly a perfect taper as can be made. Fig. 244 shows a 
 19 
 
290 
 
 GOLD INLAYS AS BRIDGE ATTACHMENTS 
 
 set of six steel cones with tapers of 1, 5, 10, 15, 20 and 25 per cent, per 
 inch taper. The longest of the six cones is three inches high and is 
 exactly like the one shown in Fig. 241. This makes it possible to remove 
 a wax washer from the wax former and from it make a gold washer, 
 which may be used either on the cone, on the wax former or on the set 
 of cones with their different tapers. If such a gold washer be made 
 under the best technic known at present it will not go to the bottom of 
 the steel cone from which the wax washer came. It will go to about 
 the place shown on the cone at the left end of Fig. 244. If it be cast 
 from pure gold, slight pressure will carry it farther down on the cone. 
 Thorough annealing and another application of pressure will carry it 
 nearer to the base of the cone. A repetition of the process of annealing 
 and application of pressure will carry it still farther down. If, on the 
 other hand, the washer be made from dark 22 carat gold, coin gold 
 or clasp metal it will be found very difficult to get the washer down by 
 
 Fig. 244 
 
 repeated annealings and applications of the same pressure as was used 
 on the pure gold washer. In fact, it will require a mallet to make much 
 progress with a washer containing as much gold as the one used, which 
 was 0.500 of an inch in diameter, 0.100 of an inch in thickness and had a 
 hole in the center 0.250 of an inch in diameter. If a washer be made 
 from the same material that contains less gold it will be just that much 
 easier to carry it to the base of the cone. 
 
 If a perfectly straight rod be placed in the wax former instead of the 
 cone with its 1 per cent, per inch taper and a pure gold washer be made, 
 it will not even start over the rod on account of shrinkage of the gold. 
 Any attempt to force it will result in an upsetting of the gold at the edge 
 of the hole in the washer. This appears to be exactly what takes place 
 when MOD cast inlays are made from cavities with parallel axial 
 walls, for it is at this place that the shrinkage of the gold first interferes 
 with placing the casting. Ffonj this it seems not only inipracticable, 
 
GOLD INLAYS AS BRIDGE ATTACHMENTS 291 
 
 but impossible to construct satisfactory MOD cast gold inlays from 
 patterns made from cavities with parallel axial walls. Some claim 
 that they can do it, but it is doubtful if their observations are correct 
 with respect to the walls being parallel, for it does not seem possible 
 in the laboratory where accurate measurements can be taken. In the 
 mouth it is not possible to tell whether the walls are parallel or not. 
 A taper of 1 per cent, per inch on the walls of most cavities is not visible 
 to the naked eye. Indeed, it is not distinctly visible on the steel cones 
 until the cone has been carried to a height of about three inches. With 
 a special caliper the author has been unable to be certain of tapered 
 axial walls until about 5 per cent, per inch had been made on the average 
 cases that have come to the clinics. (See second cone from left end.) 
 As the taper reaches 25 per cent, per inch (see cone at right end) it 
 may be seen readily even on very short cones. 
 
 With the set of cones as a guide and the special caliper the author 
 and his staff have made a careful study of the amount of taper that 
 could be used not only on the axial walls, but on the buccal and lingual 
 portions of both the proximate and occlusal parts of such cavities as 
 shoTMi in Figs. 238, 239 and 240 as well as their modifications due to 
 caries, and have the castings resist the forces of occlusion without 
 dislodgment. The results of this study lead us to believe that from 5 
 per cent, per inch (see second cone from left end) to 20 per cetit. per 
 inch (see second cone from right end) is permissible, the amount used 
 depending, first upon the length of the castiag from the cervical to the 
 occlusal, and second, upon the amount of stress to be applied. Short 
 teeth which require short castings from cervijcal to occlusal are not 
 suitable for bridge attachments in the work of mastication, for the 
 amount of resistance to lateral stress is not sufficient to hold an ordinary 
 fixed bridge. 
 
 In fact, it seems that the length of the cavity from cervical to occlu al 
 is one of the most essential factors to be considered, and upon this question 
 alone one may settle the question of advisability of using an inlay attach- 
 ment for a bridge. It seems to make little difference whether there is 
 a taper of 5 to 20 per cent, per inch provided the cavity is in a tooth 
 that is long from the cervical to the occlusal. On the other hand, if 
 the tooth be one that is short from cervical to occlusal there can be no 
 question but that the least taper consistent with the removal of the 
 wax pattern and the fitting of the casting the better will be the reten- 
 tion, though success cannot even then be expected to attend the use of 
 such teeth for attachments for bridge- work unless the pulp be removed 
 and a dowel inserted into the pulp chamber. 
 
 These deductions have led many to a deviation from the accepted 
 policy of paralleling the walls of cavities for the reception of fillings. 
 
292 GOLD INLAYS AS BRIDGE ATTACHMENTS 
 
 These deviations as shown in Figs. 238, 239 and 240 are hmited to the 
 preparation of cavities for the reception of cast inlay filHngs and bridge 
 attachments for the following reasons : 
 
 1. Parallel walls cannot be detected in cavities in teeth in the mouth. 
 It requires upward of 5 per cent, per inch on short axial walls in order 
 to be certain that there are no undercuts. 
 
 2. Parallel walls will not permit the removal of an accurate wax 
 pattern from the cavity. 
 
 3. Tapered walls facilitate the fitting, especially in M O D castings. 
 
 4. Parallel walls are not necessary for the retention of cast gold 
 inlays either as fillings or bridge attachments except in teeth which are 
 short from cervical to occlusal. In such cases it is a question whether 
 the judgment of the profession will not eventually lead us to consider 
 such cases contra-indicated for bridge attachments. 
 
 5. A sharp angle in any part of a cavity such as is shown at A, 
 Fig. 236 or A B, Fig. 237, will produce an attenuated place in the. 
 present investing materials and result in an inaccurate casting. 
 
 A study similar to the one made on the shapes of cavities for fillings 
 has been made on castings that are capable of retaining fixed bridges 
 of four and five teeth, for example, one from cuspid to first or second 
 molar or from cuspid to cuspid either in maxilla or mandible. Care- 
 ful records of scores of cases have shown that the MOD cast inlay in 
 molars (Fig. 240) or bicuspids that have their pulps in them and have 
 not had the dentin cut away between the mesial and distal portions, 
 and are of the average length from cervical to occlusal, will hold the 
 average fixed bridge of the length mentioned, provided the casting has 
 been done with an alloy of gold that is as strong or stronger than dark 
 22 carat gold. It should be obvious that a molar which has the dentin 
 cut away between the mesial and distal portions is likely to fracture 
 when the stress of a bridge involving only three teeth is attached to it. 
 A bicuspid being a smaller tooth has even less dentin on the buccal 
 and lingual walls if a channel has been cut through the dentin con- 
 necting the buccal and lingual walls by previous filling or caries, and 
 is, as a result, less desirable than a molar under such conditions from 
 the standpoint of the fracture of the tooth. Such inlays will often 
 become dislodged more easily than those made from teeth which have 
 a good septum of dentin between the buccal and lingual walls. 
 
 From the standpoint of liability of fracture of the tooth and the 
 greater chance of dislodgment, the MOD inlay seems contra-indicated 
 in cases which do not have a good, strong septum of dentin between 
 the buccal and lingual walls in either teeth with pulps in them or 
 pulpless teeth. 
 
 Many different forms of partial crowns have been suggested which 
 
GOLD INLAYS AS BRIDGE ATTACHMENTS 
 
 293 
 
 would protect the tooth from fracture, but, as a general rule, this has 
 been done without having first given special attention to the forces which 
 fracture such teeth. Some of the partial crowns that have been suggested 
 as bridge attachments have covered entirely too much of the tooth and the 
 result has been either devitalized or irritated pulps within a year or two after 
 the insertion of such a bridge. The adventitious effect of large masses of 
 metal in contact with tooth tissue has been studied by several pathol- 
 ogists, and some work has been reported which seems to indicate the 
 use of the least amount of metal in contact with the tooth tissue that 
 is consistent with strength. It is necessary that the inlay or partial 
 crown does not stretch under the stress of mastication, for if it stretches 
 even a slight amount it is usually dislodged soon afterward. The 
 stretching will manifest itself by a pulling away from the remainder of 
 the inlay of the proximate portion of the inlay that is soldered to the re- 
 mainder of the bridge. This may be prevented by making the occlusal 
 
 Fig. 245 
 
 Fig. 246 
 
 portion of the inlay deeper and wider and by extending the gold 
 around the lingual portion of the tooth as shown in the upper molar 
 (Fig. 245) and around the buccal portion of the lower molar^ (Fig. 246) . 
 These castings will stretch when pressed over a conical piece of dentin 
 but will not stretch under the stress of mastication if proper precautions 
 are taken to get the proper resistance to stress. 
 
 Some have suggested the extension of the gold toward the cervical 
 to the point A, Fig. 247, and a similar place, Figs. 245, 246 and 249, 
 but it seems to have only one thing in its favor, namely, it furnishes 
 a little more surface retention for the cement between the tooth and 
 inlay. The additional amount of metal that this extension necessi- 
 tates in contact with the tooth at a vulnerable point appears to more 
 than counterbalance any other thing in its favor. Up to the present 
 
 1 The location of the contact points on the lower molars and bicuspids usually makes 
 it more practicable to use the buccal side. 
 
294 
 
 GOLD INLAYS AS BRIDGE ATTACHMENTS 
 
 time inlays from such cavities as shown in Fig. 248 seem to be much 
 less irritating to the pulps of teeth than those which extend near to 
 the cervical portion of the teeth. This form of inlay attachment is 
 simply an M O D inlay which has been extended over to the buccal 
 and lingual surfaces sufficiently far to prevent fracture of the tooth. 
 
 Fig. 247 
 
 It^may be seen that the hold which this attachment has on the tooth 
 is much like that of a crown, though it has much less metal in contact 
 with the tooth than the crown has. This attachment has been very 
 satisfactory for pulpless teeth and for teeth with pulps in them which 
 have had the dentin between the mesial and distal portions cut away. 
 In fact this attachment is doing all that any gold crown has done in 
 
 Fig. 248 
 
 the author's hands and has been the means of nearly eliminating the 
 full crown. It permits the retention of the pulp when the teeth are 
 vital, and in all cases makes it unnecessary to employ a band, thereby 
 eliminating one of the most frequent sources of irritation and infection. 
 Fig. 249 shows tooth and an attachment for upper bicuspids similar 
 
GOLD INLAYS AS ISRtDGE ATTACHMENTS 
 
 295 
 
 to the one for molars, which has been equally satisfactory though 
 applicable in a less number of cases on account of the greater objection 
 to the exposure of gold to view as the teeth are located anterior to the 
 molars. 
 
 
 
 
 f%\ 
 
 /. 
 
 >^ 
 
 I K"v>*" 
 
 ^J/\ 
 
 \ 
 
 / If i 
 
 r-i 
 
 Kill 
 
 I •^ 
 
 ^ \ 
 
 
 
 1 
 
 L- 
 
 J| 
 
 \ 
 
 V W^ • " ~- 
 
 ■ 
 
 
 
 
 Fig. 249 
 
 Fig. 250 
 
 Fig. 250 shows a lower bicuspid, an M O D, and a partial crown pre- 
 paration. It is seldom that the MOD inlay is indicated in the lower 
 
296 
 
 GOLD INLAYS AS BRIDGE ATTACHMENTS 
 
 bicuspids, for the lingual wall is usually weak. On account of the low 
 lingual cusp, especially on the first bicuspid, and the narrowness from' 
 mesial to distal of the lingual side of these teeth, the preparation shown 
 in Fig. 250 c, is preferable in nearly all cases. The location of the 
 contacts of these teeth with adjacent teeth makes it necessary, as a rule, 
 
 Fig. 251 
 
 to make the partial crown preparation in order to get room to solder 
 the attachment to the remainder of the bridge. 
 
 Figs. 251 and 252 show MOD inlays for cuspids that will carry one 
 end of a bridge from cuspid to the first or second molar. They are 
 simply MOD inlays that have either one 22 gauge iridio-platinum pin 
 set each side of the horn of the pulp, Fig. 251, or a groove from mesial 
 to distal (A, Fig. 252) for the purpose of resisting stress from the labial. 
 
 Fig. 252 
 
 Some have suggested preparations for the cuspid teeth that were cut 
 on the lingual to the position A, Fig. 253. Such castings, however, 
 will not resist labio-lingual and bucco-lingual stresses as well as those 
 made from the cavities shown in Figs. 251 and 252, unless a groove has 
 been cut along the axial wall at B, Fig. 253. Some claim they are able 
 
GOLD INLAYS AS BRIDGE ATTACHMENTS 
 
 297 
 
 to do this, but the author has been unsuccessful in his attempts to teach 
 students to cut grooves along the axial walls of proximate cavities 
 except in the teeth of middle aged and old people. 
 
 The development of the attachment shown in Figs. 251 and 252 
 seems to meet the demands of both young and old people, and for the 
 present the grooving of all axial walls has been abandoned. 
 
 Fig. 253 
 
 Figs. 254 and 255 show preparations that have been successful in 
 central incisors that are very similar to the cuspid preparations. As 
 in the cuspid preparation the abseace of the lingual cusp makes it 
 necessary to use either the pins, A, Fig. 254, or groove, A, Fig. 255, 
 to prevent force from the labial from dislodging the attachment. It 
 
 Fig. 254 
 
 Fig. 255 
 
 should be remembered that cuspids, incisors, lower bicuspids and often 
 second lower bicuspids do not have the same resistance to forces from 
 the labial and buccal that a molar or upper bicuspid has, and when 
 an attachment for a bridge is to be made for these teeth some form of 
 resistance to these stresses must be made. Three ways have been 
 suggested, namely: 
 
298 COLD INLAYS AS BRIDGE ATTACHMmTS 
 
 1. Extension of the metal to either the labial or buccal or lingual, 
 or both walls. 
 
 2. Placing small pins in the incisal portion of the tooth. 
 
 3. Cutting a groove either across the incisal portion of the tooth or 
 along the axial walls, the latter usually applicable to teeth of persons 
 who are middle aged or older. 
 
 It may be noted that all of the attachments suggested as having been 
 successful are made on the plan of tapered walls. Scores of these 
 attachments have been inserted during the last seven or eight years 
 under all kinds of conditions except in short teeth. None, in recent 
 years, have been placed in teeth which were short from cervical to 
 occlusal, for success has not attended this kind of practice, notwith- 
 standing that the walls of such cavities have been made as nearly 
 parallel as possible, with proper protection against undercuts. With 
 the exception of the short teeth, therefore, and with proper attention 
 to the precautions pointed out with respect to liability to fracture, 
 stretching of the inlay at the occlusal portion, protection against 
 labial and buccal stresses on teeth without lingual cusps, the tapered 
 walled cast inlay attachment may be regarded one of the most 
 rational methods of practice. 
 
CHAPTER VI. 
 
 HIGH FUSING PORCELAIN INLAYS. 
 
 By W. a. capon, D.D.S. 
 
 PREPARATION OF CAVITIES. 
 
 The success of an inlay will depend largely upon four points of differ- 
 ence between its cavity preparation and that for those of foil, gutta- 
 percha, amalgam, or cements, viz., upright walls, square enamel edges, 
 no undercuts, and depth. The walls being perpendicular or nearly so, 
 allow the easy withdrawal of the metal matrix either of platinum or 
 gold, or in the case of the impression for casting with wax or any mate- 
 rial for the purpose of making a model. The enamel edges are made 
 square so that the inlay will have no overhanging frail edges of 
 porcelain. 
 
 An undercut will prevent the easy removal of the matrix frequently 
 distorting it, and when using wax not even the slightest undercut is 
 permissible. In connection with porcelain, depth of cavity has much 
 to do with retention, in fact it is more important than various keys and 
 irregular forms advocated by many writers on this subject. Unfor- 
 tunately we cannot always get sufficient depth, and, on the contrary, 
 many cavities, when entirely cleared of decay, are too deep to obtain 
 an unmutilated matrix particularly with platinum; however, when this 
 condition exists, it is an easy matter to reduce it by partially filling 
 with cement or gutta-percha. 
 
 The advantages of depth are retention, strength, through quantity 
 of material, and purity of shade by having sufficient volume of porcelain 
 which assists materially in reducing the opacity caused by the cement. 
 
 This rule pertaining to deep cavities has not the same value when 
 applied to the cast gold inlay, and it is well to note that the same rules 
 which apply to porcelain inlays are applicable to matrix gold inlays, 
 except that point pertaining to shading, because cavities prepared 
 for matrices have always the burnishing feature prominent, which 
 means curves and all surfaces accessible to the burnisher. 
 
 The formation of cavities is greatly assisted by special burs, stones 
 and chisels of various sizes and curves, as illustrated in Figs. 256 and 
 257. 
 
 (299) 
 
300 
 
 HIGH FUSING PORCELAIN INLAYS 
 
 The following representations of various cavities in natural teeth 
 where porcelain is indicated and applicable are shown with the same 
 cavity prepared and ready for the matrix. By this means the student 
 will readily note what is requisite and necessary without detailed 
 description and technical nomenclature. 
 
 4 5 6 7 8 9 10 11 
 
 Fig. 256. — Simpson's automatic chisels (proximate). 
 
 *2 
 
 1 ■ ■ 
 
 O 
 
 D D 
 
 13 
 
 Fig. 257. — ^Burs and stones. 
 
 Simple Cavities. — Figs. 258 to 265 show simple cavities, and in each 
 case the border has been extended beyond the outline of decay, for the 
 same consideration with respect to extension is applied in this class of 
 work as if the cavity were to be filled with gold. 
 
 Figs. 266 and 267 are in the same class but are more difficult, for they 
 have resulted from another cause, viz., abrasion or erosion, and it is 
 noted particularly because this condition is common, and the cavity 
 preparation much more difficult. The depth is insufficient and the 
 margins are never defined, which necessitates extensive cutting into 
 hard and unusually sensitive dentin, and as this kind of cavity is almost 
 as common in lower teeth, the difficulty of preparation and general 
 manipulation is increased. This applies to all labial cavities and is 
 
PREPARATION OF CAVITIES 
 
 301 
 
 noticed more in porcelain operations, because when the cavity is ready 
 the matrix must be held in position firmly, a procedure interfered with 
 
 Fig. 258 
 
 Fig. 259 
 
 Fig. 260 
 
 Fig. 261 
 
 Fig. 262 
 
 Fig. 263 
 
 by the lower lip and the saliva. The use of rubber dam is not desirable 
 because it reduces the working space, but it has other advantages 
 occasionally. 
 
302 
 
 HIGH FUSING PORCELAIN INLAYS 
 
 Proximate Cavities. — Figs. 268 to 277 show cavities presenting greater 
 difficulties both in preparation and general manipulation. The prep- 
 aration of cavities in such positions requires ample space between the 
 
 Fig. 264 
 
 Fig. 265 
 
 Fig. 266 
 
 Fig. 267 
 
 adjoining teeth, otherwise a matrix cannot be withdrawn or the finished 
 filling inserted. Sometimes it is impossible to get sufficient space for 
 drawing the matrix without distortion; in such instances the cavity is 
 
PREPARATION OF CAVITIES 303 
 
 prepared with this point as a first consideration. Fig. 277 shows a 
 cavity of this kind. If there is not much difference in outHne of the 
 
 Fig. 268 Fig. 269 Fig- 270 
 
 cavity labiallyor Hngually, choose the labial side from which to remove 
 the matrix; or, if cutting the labial margins does not interfere with 
 the welfare of the tooth, resort to this assistance in preference to diffi- 
 
 FiG. 271 Fig. 272 
 
 culties of lingual matrix removals. In Figs. 269 and 271 the matrix 
 under ordinary condition^ will be withdra,wn lingually. Figs. 270 ^nd 
 
304 
 
 HIGH FUSING PORCELAIN INLAYS 
 
 272 show uncertain incisal edges which are reduced in Figs. 273 and 275; 
 therefore the difficulties of drawing a matrix in this case are very much 
 
 Fig. 273 
 
 Fig. 274 
 
 Fig. 275 
 
 Fig. 276 
 
 Fig. 277 
 
 reduced, for the cavity is so large that working space is greatly ex- 
 tended. Large proximate cavities of Fig. 272 type, where the incisal 
 edge is of greater strength and is retained, are very difficult and frequent. 
 
PREPARATION OF CAVITIES 
 
 305 
 
 The matrix formation requires skill and patience, but the reward is 
 durability — for the inlay in this case is thoroughly protected and is 
 rarely unseated. 
 
 Figs. 278 and 279 show a cavity on the gingival border extending under 
 the gum margin and involving a considerable portion of the tooth 
 mesially and distally. It is a typical representation of this form of 
 cavity and the position is one demanding a restoration with porcelain. 
 The cavity walls are governed by its extent, for the matrix will warp 
 if a strict rule of upright walls is carried out here. The cervical wall 
 will not be at right angles to the pulpal wall or floor, or if so made they 
 cannot be of that form at the extreme mesial and distal border; there- 
 fore, in these cavities strict adherence to a right angle upright wall is 
 not possible for the best result. When the matrix is burnished it should 
 
 Fig. 278 
 
 Fig. 279 
 
 be packed with gum camphor in preference to other materials recom- 
 mended. It is not always possible to make a very extensive inlay of 
 this kind of one piece, therefore it should be divided at the median line 
 of the tooth and two operations made. 
 
 Proximo-incisal Cavities. — Figs. 280 to 284 represent extensive proxi- 
 mate cavities or fractures extending to the incisal edge, and in a position 
 where porcelain is of great importance. The apparent insufficient 
 anchorage deters many operators from using porcelain, and the prep- 
 aration of these cavities is the cause of more different opinions than 
 any other. It is claimed that, without a key or step on the lingual 
 surface, porcelain will not be retained by the ordinarily prepared 
 cavity, and unnecessary cutting of good tooth structure is taught with 
 most deplorable results — in many instances, irregularity of cavity and 
 its borders increase the matrix-formation difficulties, therefore a simple 
 20 
 
306 HIGH FUSING PORCELAIN INLAYS 
 
 preparation is taken advantage of. With few exceptions the cavity 
 can be prepared similarly to Fig. 280, defining the labial and lingual 
 
 Fig. 280 Fig. 281 
 
 walls and anchorage increased by a groove with a round bur at the 
 gingival border resembling a deep undercut, as for a gold filling. 
 
 Fig. 282 Fig. 283 Fig. 284 
 
 Anchorage is also increased by grooving between the enamel plates at 
 the incisai edge. The matrix must be burnished to these surfaces, 
 
PREPARATION OF CAVITIES 307 
 
 otherwise the value of the preparation is lost. The labial outline, 
 Fig. 283, can be varied in many ways, but angles are to be avoided 
 whenever possible. Very often the corner is of the form of an 
 irregular triangle tapering to a wedge point at the cutting edge. The 
 porcelain at that point is very frail and will break, leaving an irrepar- 
 able notch. To avoid this, cut an axial wall as in Fig. 284, and thus 
 make a body of porcelain, giving strength at a weak point. This same 
 cavity is sometimes so extensive that anchorage is made by wire pins 
 or staples. In instances where the incisal section of the tooth has 
 been lost by accident or decay, this process of retention is preferable 
 and highly recommended for permanency. 
 
 Fig. 285 
 
 Fig. 285 shows a central tooth, a matrix, and the porcelain section with 
 wire anchorage. This case shows loss of one-fourth of the tooth and 
 the cavity made by cutting the dentin to the required depth, an opera- 
 tion possible with few exceptions. The enamel edges are made true 
 by a fiat stone, after which the matrix is made of the walls and edges, 
 and shown without a floor. The wire is iridio-platinum, gauge 24, 
 made in the form of a staple or loop, and inserted while the matrix 
 is in place; with these in position, porcelain in paste form is pressed 
 over all and excess moisture is absorbed by holding a napkin or bibu- 
 lous paper to its surface. The combination is carefully taken from the 
 cavity and fused, thus forming a base with a wire loop or pins held 
 securely without soldering. This foundation is now placed on the 
 tooth and matrix edges thoroughly burnished, after which the opera- 
 tion is completed by repeated fusing. When the matrix is removed, 
 the contoured tip will resemble the third section of Fig. 286, and is ready 
 for cementing. When the first porcelain is applied it will likely fill the 
 loop, but this must not be corrected until after fusing, when the porce- 
 lain is easily broken away with blunt pliers. Frequently the staple or 
 loop is inverted to suit conditions, but the form represented is the 
 most durable in every particular. The difficulties of this operation 
 are increased by the irregular form of fracture, for usually they extend 
 lingually and frequently quite to the gum margin; a restoration of 
 
308 
 
 HIGH FUSING PORCELAIN INLAYS 
 
 this kind should not be attempted until the operator has had con- 
 siderable practice, for the making of an incisal tip acceptably is one 
 of the most difficult operations. 
 
 Fig. 286 
 
 Fig. 287 
 
 Fig. 288 
 
 Fig. 290 
 
 Fig. 291 
 
 Fig. 292 Fig. 293 Fig. 294 Fig. 295 Fig. 296 
 
 Figs. 286 to 296 show the staples in various applications, including corner restorations. 
 
 Bicuspid and Molar Cavities. — Figs. 297 to 306 show cavities in bicus- 
 pids and molars for porcelain inlays. The forms are very similar and 
 directions for cavity technique are applicable in either instance. The 
 value of porcelain in these positions is questioned because the force of 
 
 Fig. 297 
 
 Fig. 298 
 
 Fig. 299 
 
 contact is increased and the esthetic value is decreased. There are 
 many exceptions, and the opportunities exist in mesial surfaces of 
 superior biscupids and molars. The occlusion is the first consideration, 
 size and depth of cavity are next, although the latter is generally 
 
PREPARATION OF CAVITIES 
 
 309 
 
 regulated by a step as shown in the sketches. This step is made of 
 cement or gutta-percha and not of the same extent as if preparing for 
 
 Fig. 300 
 
 Fig. 301 
 
 a gold inlay. The gingival borders are more curved and the step is 
 rounded and allowance made for greater thickness of porcelain at the 
 occlusal surface. The inlay will be more secure without a step or 
 
 Fig. 302 
 
 Fig. 303 
 
 interior preparation of any other material, but bicuspid and molar 
 cavities are usually too deep for successful matrix formation. If 
 
310 
 
 HIGH FVBING PORCELAIN INLAYS 
 
 this can be accomplished, there still remains the difficulty of placing 
 the inlay, because of greater bulk than it is possible to get space for; 
 however, there can be no set rule, circumstances and good judgment 
 
 Fig. 304 
 
 Fig. 305 
 
 must be factors at all times. In any case the cavity must not extend 
 into the sulci between cusps unless the sulci are of sufficient size to 
 assure strength of porcelain. Figs. 302, 304 and 306 show enamel sur- 
 face edges without any extension to the sulci. 
 
 F 
 
 ^ 
 
 1 
 
 ■ 
 
 1 
 
 ^.«#*" 
 
 Hre" ■ 
 
 1 
 
 ^H 
 
 p^'^l^l 
 
 K: 
 
 rl 
 
 ^^^K -n 
 
 B 
 
 1 
 
 
 Fig. 306 
 
 The following illustrations represent what may be termed unusual 
 cavities both in form and extent for porcelain inlays. 
 
PkEPARAfiON OF CAVlfiM 
 
 311 
 
 Fig. 307 incisal edge, requiring very accurate adaptation because of 
 small opportunity of retention. If the mesial and distal walls are not 
 too thin on the incisal enamel, a groove in the cavity will assist, but 
 the general form of the tooth will govern this suggestion. 
 
 Fig. 308 an unusually large form of labial cavity extending to the 
 extreme mesial and distal borders and leaving only the lingual enamel 
 plate. 
 
 Fig. 309 a labial cavity toward the incisal edge more frequently 
 seen at the gingival border. 
 
 Fig. 307 
 
 Fig. 308 
 
 Fig. 309 
 
 Fig. 310 represents a tj^e of preparation for a porcelain tip, the 
 original enamel being defective in form and color. 
 
 Fig. 311 a mesial cavity extending from the gingival border to the 
 incisal edge of a central. Cavity converging extensively labially and 
 the lingual cutting edge shortened because of decay and weak enamel. 
 
 Fig. 310 
 
 Fig. 311 
 
 Fig. 312 linguo-mesial cavity extending to incisal edge. Lingual wall 
 reduced because of weakness of enamel, but that loss is added strength 
 to the porcelain inlay. 
 
 Fig. 313 an extensive labial cavity involving the whole mesial surface 
 and extending lingually. In preparing this cavity the pulpal wall 
 angles must not be so acute that the matrix cannot be withdra-wn from 
 the incisal section between the enamel plates or reducing the axial 
 wall at the incisal edge to a plaia surface may be necessary to prevent 
 distortion of the metal. 
 
312 
 
 BIGH FUSING PORCELAIN INLAYS 
 
 Fig. 314 incisal, labial and lingual preparation with angles to assist 
 retention. 
 
 Fig. 315 lingual preparation for mesio-incisal restoration, more appli- 
 cable to gold inlays. This form of retention for porcelain is not gener- 
 
 FiG. 312 
 
 Fig. 313 
 
 ally recommended because of increased difficulty in obtaining a matrix 
 from the under surface and the doubtful assistance of a substance of 
 such friable composition. 
 
 Fig. 314 
 
 Fig. 315 
 
 PORCELAIN RESTORATION FOR CHILDREN'S TEETH. 
 
 One of the most difficult operations for any dentist is the restoration 
 of a broken permanent incisor of a child between the ages of seven and 
 twelve years. The tooth is generally broken by an accident and fre- 
 quently the pulp is not affected, but the tooth is extremely sensitive. 
 If the pulp is exposed, devitalization is the only resort, and the restora- 
 tion can be made with porcelain, using an iridio-platinum pin extending 
 into the canal, or a wire loop of the same metal. No. 24, anchored in 
 the remaining part of the crown. 
 
 This work is comparatively easy, because the main requisite for 
 strength is anchorage, which is possible under these conditions. When 
 the pulp is alive and apparently healthy it is generally desired that such 
 a condition be preserved, which is not an easy matter under these 
 
PORCELAIN RESTORATION FOR CHILDREN'S TEETH 
 
 313 
 
 circumstances. Something must be applied for protection, and there- 
 fore cement is used because of its tenacity. No mechanical anchorage 
 is possible. The child is young and the teeth are undeveloped, there- 
 fore they must be kept comfortable, if not presentable, for some years, 
 for it is my experience that a case of this kind at the age mentioned 
 is irresponsible and the dentist must bear the burden, which means con- 
 tinual replacement and general botheration. I recommend, therefore, 
 that nothing permanent be attempted until the case has arrived at an 
 age of maturity, when the patient is willing to use care with what has 
 been done and has arrived at the age when personal appearance has 
 some value. 
 
 A girl patient will be ready for a permanent operation about two 
 years before a boy. Therefore, it is fairly safe to consider a finished 
 operation at the age of thirteen to fifteen years. In the meantime, 
 during the intervening years, fracture surfaces must be covered in some 
 agreeable manner, and to that end I present the following plan of 
 making a presentable restoration. 
 
 Fig. 316 
 
 Fig. 317 
 
 Fig. 316 represents the case of a boy, aged eight years, left central 
 broken by a fall, pulp not exposed, but too sensitive to allow any instru- 
 mentation whatever. I kept the surface covered with cement for one 
 year, which demonstrated the fact that the pulp was not materially 
 affected by the fracture. The parents insisted that something more 
 presentable be done, so an accurate impression of the broken section 
 was taken in plaster, and, after drying, a model was made of Mellotte's 
 metal. Platinum foil No. 38 was swaged to fit the broken surface, 
 extending lingually to the gum line and labially one millimeter. 
 
 This formed an accurate shell, which covered the tooth except on 
 the labial and proximate surfaces. This thin platinum form was then 
 reinforced by 25 per cent, platinum solder and a small staple attached 
 to the broken surface (Fig. 317) for the purpose of holding the porcelain. 
 After three fusings the restoration was completed as shown in Fig. 318. 
 The small line of platinum on a labial surface did not detract from the 
 finished operation to any objectionable extent because the porcelain 
 
314 
 
 til Gil FUSING PORCELAIN INLAYS 
 
 corner was so much greater in size; however, the improvement quite 
 paid for the trouble. 
 
 Wire used for the staple was iridio-platinum No. 24. The surface 
 of porcelain contact was etched to give every opportunity of attach- 
 ment. This case was in use for five years and had the advantage of 
 easy replacement of either the whole shell or repair of porcelain if 
 necessary. If gold is preferred, the metal can be cast direct to the 
 foundation, which should be made of gold instead of platinum. 
 
 Fig. 318 
 
 FORMATION OF THE MATRIX FOR PORCELAIN. 
 
 The difficulties pertaining to the making of a matrix are much 
 reduced by having plenty of space between the teeth, and this must be 
 obtained prior to the operation by means of tape, cotton, or rubber 
 wedges. Mechanical appliances may be used as an assistant when the 
 inlay is made and the space for easy insertion is insufficient, but holding 
 the teeth apart while making the matrix is usually an interference that 
 can be avoided by giving this part of the work proper consideration. 
 Room to work is a good rule to follow in any operation, but it is posi- 
 tively necessary with the inlay, because the mass is hard and unyield- 
 ing with breakable edges. It must be placed while the cement is soft, 
 and without delay, and the slightest interference may mean much loss 
 of time and poor results. 
 
 A gold inlay can be forced to place without damage, but an 
 unpleasant experience or two with porcelain will demonstrate the 
 desirability of having plenty of space. 
 
 The reproduction of the form of a cavity in foil for an inlay is called 
 the matrix, in which the porcelain is moulded by heating to a degree 
 required to fuse the component parts of the material to a vitrified mass. 
 The metal most generally used is pure platinum foil, tto¥ of an inch 
 in thickness. Gold foil No. 40 is also largely used, but only in connec- 
 tion w^ith a low fusing porcelain which fuses at a temperature of 300° 
 to 500° less than gold. Platinum has the advantage in the fact that it 
 cannot be affected by any heat required to fuse the highest grade porce- 
 lain. It is not so ductile, nor so easily moulded to form, but this dis- 
 
PORMATiON OF THE MAfRIX FOR PORCELAIN 
 
 Sl5 
 
 advantage is counterbalanced by its stability, which allows greater 
 freedom from care as to the changing of its form while filling with 
 porcelain. 
 
 A gold matrix is invariably invested to prevent its changing form 
 and protect it from overheat. This requires time and care, therefore 
 platinum is more desirable from many points, and practice will assist 
 greatly toward easy manipulation. There has been much discussion in 
 the past upon the proper thickness, but it is now generally conceded 
 that ToV 0" of an inch will suit all cases better than any degree thinner 
 or thicker. A thinner material has not the stretching quality, and 
 an3i;hing heavier will cause a thicker cement line. 
 
 Fig. 319 
 
 A simple cavity on the labial surface of a central will serve to illus- 
 trate the mode of procedure, which is the cutting of a square section 
 of the foil sufficiently large to extend over the adjoining teeth, holding 
 the corners in the manner of Fig. 319, and while held securely by the 
 fingers, press the foil over the cavity with some material such as spunk, 
 cotton, small chamois disks, or a soft rubber point like a pencil end, and 
 in this manner the cavity will be outlined on the foil and that portion 
 covering the cavity concaved so there can be no mistake as to what 
 portion is to be burnished. Then use ball-pointed burnishers of various 
 sizes, such as amalgam instrmnents shown in Figs. 320 to322,and gently 
 rotate, gradually pushing the burnished surface to the cavity walls and 
 floor, using care not to break the margins. The metal will probably 
 split or break as it is forced to place, but unless extremely ruptured, it 
 will not interfere with final results. When the interior portion is fairly 
 fitted, packed with spunk, cotton, or gum camphor, and held seciu-ely 
 with a blunt instrument, a flat, blunt instrument should be used to get 
 perfect margins. Then the packing is removed (except when using 
 camphor, which is biunt out), the matrix released with very fine 
 
316 
 
 HIGH FUSING PORCELAIN INLAYS 
 
 pointed pliers, and results noted. Three desirable sets of burnishing 
 instruments are illustrated in Figs, 323, 324 and 325. 
 
 If satisfactory, the next step is filling the 
 mold with porcelain. 
 
 Platinum foil should be thoroughly an- 
 nealed in the furnace muffle; the heat re- 
 quired to improve its softness is at least 
 2200° F. The foil purchased at the present 
 time is usually ready for making the matrix, 
 having already been thoroughly softened at 
 a very high temperature. A matrix of 
 complex character will require more than 
 usual burnishing, which will have a ten- 
 dency to make the metal harsh. It can 
 then be re-annealed to advantage, provided 
 the temperature is not less than the degree 
 already mentioned. 
 
 An excess of material is recommended in 
 labial cavities for the purpose of holding 
 securely, but in other places the reverse 
 ..i i^ ^1 is desired; notably on proximate surfaces, 
 where the excess will interfere with removal 
 after taking the form of the tooth. Bur- 
 nishing the matrix in proximate cavities, 
 corners, and tips is greatly assisted by 
 strips of either cotton, rubber dam, or gold- 
 beater's skin held securely over the metal, 
 insuring its proper position and preventing 
 tearing on the sharp cavity edges (Fig. 326). 
 Avoid lapping or folding of matrix on cavity 
 edges. 
 
 After the matrix is made, the next pro- 
 cedure is filling it with porcelain. This is 
 done by holding the mold in straight, fine- 
 pointed pliers, applying the porcelain with 
 a fine sable pencil brush, or the end of a 
 spatula made for the purpose (Fig. 327). 
 The porcelain powder is mixed with pure 
 water, distilled preferably, into a stiff paste. 
 Fig. 320 Fig. 321 Fig. 322 and after applying, it is shaken to position 
 
 either by tapping or drawing the serrated 
 instrument handle across the pliers. This jarring brings the moisture 
 to the surface, and after tracing the cavity outline and removing 
 
FUSING THE INLAY 
 
 317 
 
 excess with brush, it is laid face down on a clean towel, bibulous or 
 blotting paper, which absorbs the excessive moisture. The inlay is 
 
 4 5 6 7 8 9 10 
 
 Fig. 323. — Reeves set of inlay burnishers. 
 
 then dried out in front of the furnace mufHe, gradually pushed 
 into the furnace, and fused. Too rapid drying will cause 
 porcelain to jump from the mold. A high fusing porcelain 
 mixed into a stiff paste will shrink about one-fifth its bulk, 
 therefore a second or third fusing is required before the inlay 
 can be called finished. If the porcelain is thin, its proportion 
 of shrinkage will be greater, and it will not bridge or carry its 
 weight across any tear or aperture that may exist in the 
 bottom of the matrix; and in deep cavities this condition is 
 nearly always present; therefore it is necessary to always 
 turn the matrix wrong side up and carefully note its condi- 
 tion. Clean ofi^ any excess with the brush and thus avoid a 
 misfit, for it is impossible to remove fused porcelain without 
 distorting the matrix or totally destroying the work up to 
 this point. 
 
 FUSING THE INLAY. 
 
 The first fusing is usually called "first bake" or "biscuit," 
 which is a stage wherein the component parts of porcelain are 
 brought together by the heat and made into a hard, homo- 
 geneous mass without gloss. 
 
 It is at this stage that shrinkage is most apparent, and it is a 
 condition that exists in every porcelain operation of whatever 
 dimensions. Shrinkage is governed by quantity and quality of material 
 and is a prominent factor toward success or failure. In small inlays shrink- 
 age is of less import, but in proportion to size it must be dealt with. This 
 
318 
 
 HIGH FUSING PORCELAIN INLAYS 
 
 shrinkage may be sufficient to distort the matrix or cause porcelain to 
 attach to the matrix walls. As it is never consistent, it is very impor- 
 tant to control it, but this is only possible to a small extent. Shrinkage 
 toward the matrix wall is most desired and can be assisted by a slight 
 cut or groove across its greatest extent, thereby giving the porcelain 
 an impetus in that direction. In large spaces much assistance in con- 
 trolling shrinkage is derived from using small particles of baked 
 porcelain mixed with the unfused paste. 
 
 Fig. 324. — ^Weber's glass burnishers. 
 
 After the first fusing of the inlay the excess platinum or matrix 
 material should be trimmed, leaving a working margin to allow a 
 refitting in the cavity. In small, simple cases this may not be neces- 
 sary, but in the majority of cavities it will assist greatly. If the matrix 
 has become slightly altered by shrinkage or careless handling, the change 
 is noted at once and corrected. In contour work it will assist the eye 
 to determine where to add or reduce; in fact, there can be only very 
 small argument against a trial of the embryo inlay in its place and 
 reburnishing the cavity edges. 
 
FUSING THE INLAY 
 
 319 
 
 Selecting the shade is the first requirement, as the foundation should 
 approximate the final shade, but after the inlay is reburnished, this 
 
 2 3 4 5 6 
 
 Fig. 325. — Sausser's matrix burnishers. 
 
 question must be settled in the operator's mind, and the 
 final fusing proceeded with. First, clean off the inlay with a 
 brush dipped in alcohol or warm water, thus removing saliva, 
 blood or any undesirable particles, then carefully fill any crevice 
 caused by shrinkage or breakage, finally filling the matrix or 
 building the contour or section as desired, always considering 
 shrinkage. A second bake may be sufficient, but usually a 
 third is required or even a fourth. Frequent firing is not 
 harmful, provided the porcelain has not been carried to a 
 finishing heat previously. Shrinkage must be overcome, 
 therefore withdraw the work from the furnace before it is 
 fused and note its condition. 
 
 After the inlay is properly fired the matrix is removed by 
 turning the metal back from the edge with pointed pliers, re- 
 leasing the inlay. Frequently small particles of metal adhere 
 to the porcelain. If a pointed instrument fails, use a discarded 
 bur, but in larger inlays small quantities of adhering metal will 
 make no difference in any way. The inlay is now tried in place, 
 having the cavity wet, which helps the porcelain to blend with 
 the natural tooth, and at this stage the patient should be 
 shown the results, for at a later period the cement and dry- 
 ing of the tooth make a change not always satisfactory, but 
 fortunately this is largely corrected by time. 
 
 The inlay is grooved or undercut by wheel disks such as 
 hard-rubber, corundum, or copper coated with diamond dust. 
 An additional retention is secured by using hydrofluoric acid. 
 This acid has a great affinity for all vitrified surfaces, therefore 
 great care is necessary that the outer and finished surface is ^ 
 thoroughly protected, and the most simple method is to soften the 
 surface of a small piece of paraffin or beeswax, and embed the inlay face 
 
320 
 
 HIGH FUSING PORCELAIN INLAYS 
 
 downward . Then cover the exposed surface with a few drops of the hydro- 
 fluoric acid, and after about five minutes wash with a spray of water . 
 The use of acid for this purpose is very common, and the tendency 
 to carelessness is sometimes checked by a bad burn, which is always 
 
 Fig. 326 
 
 painful and very slow to heal. After the 
 inlay has been subjected to acid, it should 
 be soaked in alcohol, which will soften the 
 white scale, which is removed by scraping 
 the surface with a sharp instrument, and 
 thereby give the cement a better attach- 
 ment to the roughened surface. This is a fjq 327 
 point not generally considered, but it is 
 reasonable and practicable, and many small inlays have 
 been lost through non-observance of this fact. 
 
 As the inlay is now ready for inserting, the tooth is dried 
 and protected from moisture either by napkins or rubber 
 dam. The latter is preferable, but not necessary, provided 
 the operator can use a napkin properly. Successful inlays 
 depend upon perfect adaptation and cementation, but 
 frequently the operation is spoiled through carelessness 
 or a desire to hurry the case to a finish, therefore too much 
 stress cannot be placed on this important part of the work. 
 The cement, the shade of which should approximate that 
 of the tooth and inlay, must be mixed thoroughly, be of 
 creamy consistency and of medium to slow setting quality. 
 Apply it to the cavity with a small spatula tip, then 
 gently press the inlay into position, wipe off excess with 
 spunk or tape, and note the line of demarcation. If this 
 is satisfactory, hold the inlay in position until the cement 
 has commenced to harden, then protect from moisture 
 by covering with melted paraffin, wax, sandarac varnish, 
 or chlora-percha. If the inlay is extensive, it can be ligated 
 with floss silk or held by a wedge, always avoiding the 
 use of excessive force, or the delicate porcelain edges will 
 shatter. 
 
 ^ 
 
 Fig. 328 
 
MAKING INLAYS BY THE INDIRECT METHOD 321 
 
 A later sitting is required for a final finishing, for the best of inlays will 
 need smoothing of edges, which is done with small stones or sandpaper 
 disks and strips. 
 
 MAKING INLAYS BY THE INDIRECT METHOD. 
 
 While the majority of porcelain workers are satisfied that the best 
 results are to be obtained by working directly on the tooth from start 
 to finish, it is claimed by others that results equally as good may be 
 had by swaging, or by what was originally known as the water-bag 
 process, introduced a few years ago by a London manufacturing firm. 
 
 The system has some ardent supporters who claim that by it the 
 presence of the patient is needed only for the impression and the finish 
 of the inlay, the rest of the operation being done in the patient's absence 
 and by a laboratory assistant if so desired, The claim is plausible, and 
 from the fact that many dentists use this process, it is worthy of 
 consideration. 
 
 Dr. F. T, Van Woert is an ardent supporter of this form of operating, 
 and in an article on this subject says: "The essentials necessary for 
 securing an accurate impression of any cavity are (1) suitable trays; 
 (2) proper impression material; and (3) a knowledge of its manipula- 
 tion. 
 
 " The material for trays which has given me the most satisfaction is 
 sheet platinoid of 32, 34 and 36 gauge, because it has a rigidity, to- 
 gether with more pliability than any other metal that I have been able 
 to find. Another very good quality, while not essential, is that it has a 
 finely finished surface, which at least has the appearance of being clean, 
 and is pleasing to the patient. The second requisite is the impression 
 material, and while it is a matter of opinion, personally, I prefer that 
 made by the Detroit Dental Mfg. Co., because it softens at a lower 
 temperature, sets quicker, and when cold is as hard if not harder, and 
 gives a very much sharper definition of detail than others I have tried. 
 After forming the tray, a suitable quantity of compound is heated, the 
 tray held over the flame until it is hot enough for the material to adhere 
 to it, and the compound then pressed into a cone-shaped mass with the 
 fingers and then chilled. The surface of the cone should be held in a 
 small flame, so that it is quickly heated to the point of running, and 
 then forced into position, and either compressed air or cold water used 
 for setting it. 
 
 " I find it a great advantage in large cavities in molars and bicuspids 
 
 to force between the tray and adjoining tooth the blade of a thin cement 
 
 spatula to bring up a sharp line at the cervix. This is easily removed 
 
 after the chilling, and facilitates the removal of the impression as well. 
 
 21 
 
322 HIGH FUSING PORCELAIN INLAYS 
 
 This is frequently advantageous in approximate cavities of the anterior 
 teeth also. 
 
 "Method of Making Amalgam Models. — If we have succeeded in 
 securing an accurate impression, it is only the beginning of a successful 
 ultimate result, and the next procedure, that of making the model, 
 requires as careful consideration and manipulation as any part of the 
 technic. Various materials have been recommended for this purpose, 
 all of which I have given a most careful and impartial trial, and I am 
 forced to the conclusion that there is but one reliable material, and that 
 is a good amalgam. When I say 'a, good amalgam,' I mean one having 
 good edge strength, as little shrinkage as possible, and the propert}^ of 
 setting quickly, although this is not essential. I use the standard alloy 
 made after one of Dr. Black's formulse. 
 
 "First the impression must be embedded in plaster to a sufficient 
 depth, and with enough body surrounding it to permit of pressing the 
 amalgam well down into the impression. The amalgam is then mixed 
 with enough mercury to make it very plastic, and this is burnished into 
 place with suitable instruments until the impression is filled. Then the 
 excess of mercury can be eliminated by folding a piece of rubber dam 
 several times, and placing it on the amalgam and pressing upon it with 
 the thumb. 
 
 " The mixing of the amalgam is one of the most important points in 
 the procedure. In my early efforts I tried to fiU these impressions as I 
 would a cavity in a tooth, and the force required in burnishing it to 
 place invariably marred the impression which resulted in an imperfect 
 model of the cavity. 
 
 "Advantages of Impression Method. — If we succeed in getting an 
 accurate model, a filling made to fit it must fit the cavity which it repre- 
 sents. This being the case, let us consider the advantages to be derived 
 from the impression method : first, we are none of us so perfect in any 
 branch of our art that we are not liable to make mistakes. Second, it 
 is beyond question thai we all have many accidents that are just as 
 deplorable as the mistakes we might make, and when such happen in 
 the direct method of making inlays, we are obliged to acquaint our 
 patients with the fact that we have erred, or met with a misfortune in 
 the form of an accident, either of which is humilitating to the operator 
 and frequently exasperating to the patient, and, occasionally, to such 
 an extent that the patient loses confidence and seeks service elsewhere. 
 
 "We will take, for example, porcelain restorations. In the direct 
 method, where the matrix is burnished to the cavity, which, by the way, 
 is a much more tedious operation than that of taking an impression, 
 we have confronting us the possibility of some distortion in its removal, 
 or, perhaj)s, in the handling after it has been successfully removed^ a§ 
 
SWAGING THE PLATINUM MATRIX 323 
 
 well as the possibility of warping in the fusing of the porcelain itself. 
 There is still further the difficulty which arises in many cases of securing 
 a suitable color, or just the proper form of contour, all of which is a large 
 combination of defects which remains to be explained to the patient. 
 
 "The impression method eliminates all of these difficulties. In the 
 first place, the matrix is secured by swedging the gold into the die with 
 the Brewster press (Fig. 329) and the swedged matrix is less likely to 
 change its shape when removed than the burnished one. The shape of 
 the swedged matrix can be retained by filling it with a hard wax; it is 
 then removed and invested, and later the wax washed out. Should 
 the filling prove a failure, another, or several others, if necessary, can 
 be made without the patient's knowledge; and where the question of 
 color or contour is liable to cause trouble, several fillings, varying from 
 a light to a dark shade, can be made; or if it be a troublesome contour, 
 several of different shapes, so that when the patient presents, the 
 suitable filling can be selected without subjecting him to another or 
 several operations, and without the unnecessary loss of time to the 
 operator. 
 
 "Cast-gold Fillings. — The same procedure is applicable with cast- 
 gold inlays, with the exception that the wax filling is fitted to the tooth, 
 as described by Dr. Taggart, omitting the final carving of detail in bite 
 and contour which should be done to the die. If the die is correct, the 
 wax filling will go to place without difficulty; but one is surprised to 
 note the little defects in the filling, such as here and there a small point 
 where the wax has not conformed to the sharp edge of the cavity mar- 
 gin. This is due to the lack of resistance at such places; the wax being 
 of one temperature throughout its entire body, it is forced by the occlu- 
 sion from inward out, and on a line with the cavity margin. It may be 
 said that this defect can be remedied by running a hot spatula around 
 the line, but I have found this extremely difficult, particularly at the 
 cervix. It is also claimed that such defects may be corrected by biu- 
 nishing the gold casting after it has been cemented to place. This has 
 proved just as difficult and unreliable in my hands; and it is a potent 
 point that these difficulties do not exist when cast fillings are made 
 from the impression and amalgam model properly constructed." 
 
 SWAGING THE PLATINUM MATRIX. 
 
 The cavity is prepared as described for the usual method, edges 
 square, margins strong, and without undercut. Talcum powder is 
 rubbed into the cavity and on the adjacent surfaces. 
 
 Then an impression is taken in cement. This is invested in plaster 
 of Paris, and the surplus cement which extended around the tooth on 
 
324 
 
 HIGH FUSING PORCELAIN INLAYS 
 
 both sides of the cavity is trimmed away to about one-sixteenth of an 
 inch from the margins. Additional cement is then mixed to a very stiff 
 consistence, the fingers being dipped in talcum powder and the cement 
 
 Fig. 329 
 
 Fig, 330 
 
 well kneaded. The first impression is surfaced with talcum, and this 
 second mix pressed into the first one and allowed to stand until quite 
 
 Fig. 331 
 
 Fig. 332 
 
 hard. Then separate and invest this second impression or model in one 
 of the steel cups, in plaster, or, if preferred, in one of the very shallow 
 cups, in cement or sealing wax. Invest so that the center is slightly 
 
SWAGING THE PLATINUM MATRIX 
 
 325 
 
 higher than the edges of the cup. When the plaster Is hard, place a 
 square piece of platinum (one one-thousandth of an inch thick) on the 
 cement model. With pledgets of cotton wool press the platinum down 
 into the cavity; put into the swager, with a water bag over the wool, and 
 swage. Remove from the swager and burnish out wrinkles or folds; 
 then anneal well in the furnace, replace on the model and re-swage with 
 water bag, but without the wool. Reverse the press handles, remove 
 the cup from the cylinder, and examine the matrix. If any wrinkles or 
 folds still remain on the margins, they must be burnished out; and if the 
 matrix does not appear to be perfectly adapted to all parts of the cavity, 
 it should be again annealed and then subjected to harder pressure in 
 
 Fig. 333 
 
 the swager. Any crack in the matrix at the bottom or near the bottom 
 of the cavity will not affect the fit of an inlay. 
 
 In building in the porcelain where the cavity is a large one, first grind 
 an "inlay rod" to fit tightly across the matrix at its widest part; sur- 
 round this, except upon its upper surface, with foundation body; and 
 when it is quite dry, bake. Keep the foundation body sufficiently away 
 from margins to allow for the thickness of enamel body necessary to 
 produce the desired color. When baked, return to the model, and if 
 baking the foundation body has caused any change in the fit of the 
 matrix,*the next swaging will correct it. After this last swaging pro- 
 ceed to fill in the enamel body. Lay the dark shades in first and bake; 
 
326 HIGH FUSING PORCELAIN INLAYS 
 
 then add the Hghter colors necessary to finish. The foundation body 
 first baked in the matrix will prevent any change of form during the 
 baking of the enamel body. 
 
 The press should be screwed to the bench. The solid rubber is for 
 swaging heavy metal cusps and also for inlays. Should a water bag 
 break, carefully dry out the cylinder and plunger. Do not allow any 
 rust to accumulate in the cylinder. The inlay rods above mentioned are 
 made of high fusing material and are of assistance in large contour work 
 by other methods. 
 
 The most recent appliance for this process is the Roach model press 
 with trays which are cut to form of cavity and are recommended for 
 bicuspids and molars (Figs. 330, 331, 332 and 333). 
 
 FUSING PORCELAIN. 
 
 For many years there was much controversy regarding the qualities 
 of various products, particularly between the advocates of a high heat 
 porcelain and those of low fusing qualities. While this question is still 
 debatable, it is an indisputable fact that in America porcelains of the 
 higher grade have the preference. This may be from the fact that 
 the manufacturers of artificial teeth in this country have always used a 
 high fusing material, and as the product has stood the test of time, it is 
 only natural to apply this argument to the inlay question. 
 
 English tooth body fuses about 400° F. lower than the highest fusing 
 American body, which places the English on our list as a medium fusing 
 material, and its excellent quality is indisputable; in fact, the majority 
 of our inlay bodies fuse at a medium heat, ranging from 2150° F. to 
 2300° F., therefore the difference between this fusing degree and that 
 of low body of 1600° F. or thereabouts is the point of argument. 
 
 When porcelain inlays were introduced, the standard material was 
 the continuous gum bodies then well known to porcelain workers and 
 put on the market for their use. It was the only material to be had, and 
 while it possessed the required quality, it had no variety of shade. 
 After some years this was remedied, and the advent of the pyrometer 
 enabled us to learn the approximate fusing temperatures of the old 
 continuous gum bodies which were found to be about 2300° F. These 
 bodies have not been much improved upon either in quality or finish. 
 The first low fusing material was introduced in 1892 by Dr. Downie, 
 but was not satisfactory for inlay work because of its poor shades, 
 although it was quite extensively used for crowns. A few years later 
 Ash & Sons made up a small assortment much improved in shades. 
 Dr, Jenkins introduced his low fusing enamel in 1898. After this 
 
t'VBiNG PORCELAtn 327 
 
 date manufacturers of porcelain produced an assortment suitable to 
 all circumstances. 
 
 The wearing qualities of various porcelains are practically equal in 
 certain positions, notably in cavities not extending to incisal edges or 
 masticating surfaces, and in shallow labial cavities. Low fusing porce- 
 lain has an advantage from the fact that its opacity prevents the cement 
 from changing the shade, which is frequently the case with a high 
 fusing and more translucent body. 
 
 Workers of higher fusing porcelain will be more or less conversant 
 with all porcelains and their variations, because this field is greater 
 and has practically no limitation; but a low fusing porcelain worker is 
 usually at sea if not using that material, while anyone accustomed to 
 the higher heats can fuse the lower, provided care is used not to over- 
 heat. Too much heat is fatal to low fusing body, as it means not only 
 loss of shade, but also loss of strength. The same rule applies to all 
 porcelains, but not to the same extent if the porcelain is high fusing, 
 for its working latitude is much greater. Low fusing material is usually 
 molded in a gold matrix which is invested. Platinum must be used 
 as the matrix for higher heat porcelains, and no investment of it is 
 necessary. 
 
 As pyrometers are commonly used, a list of the most popular bodies, 
 and approximate fusing points will assist the student, bearing in mind 
 that these figures are based on two-minute tests, with conditions favor- 
 able for accuracy. 
 
 Low fusing. Medium fusing. 
 
 Ash & Sons, 1550° F. S. S. White's Medium, 2100° F. 
 
 Jenkins, 1550° F. Ash & Sons' "High," 1900° F. 
 
 High fusing. 
 S. S. White's Inlay, 2300° F. 
 Close's Continuous Gum, 2300° F. 
 Whiteley's Inlay, 2200° F. 
 Whiteley's Inlay special, 2400° F. 
 Consohdated Inlay, 2600° F. 
 Johnson & Lund's, 2500° F. 
 
 It is generally conceded that fusing porcelain is one of the greatest 
 difficulties that must be overcome before the novice can feel that he 
 has made any advancement toward the successful making of an inlay 
 or anything in which porcelain is the component part. It is an indis- 
 putable fact that this part of the work is a veritable stumbling block, 
 and the cause of much discouragement which is only overcome by per- 
 sistent practice, for without this necessary knowledge successful results 
 are not possible. 
 
 Porcelain may have a fusing point as low as 1600° F., and varying 
 to 2600° F. or even higher, therefore the operator must become familiar 
 with these varied heats and their productions. This will mean contin- 
 
328 HIGH FUSING PORCELAIN INLAYS 
 
 uous application and training the eye to the various stages and changes 
 of the material. Using a timepiece with a pyrometer will be of great 
 assistance, but the personal equation is always the dominant factor, and 
 herein lies the difficulty of giving directions that will be accurate 
 under all conditions. Before the advent of the pyrometer the eye was 
 the only test of heat, therefore to the beginner this device has consid- 
 erable value, together with the fact that the fusing points of the numer- 
 ous porcelains are known. Thus a certain time by the watch with the 
 fusing point of the porcelain already known and the pyrometer showing 
 the temperature, the fusing of porcelain seems comparatively easy. 
 Various sizes of porcelain require different heats, therefore it is abso- 
 lutely necessary to know porcelain in all its changes, without any 
 assistance whatever, otherwise the work will be either over or under- 
 fused, and only by chance will it be correct if the machines are depended 
 upon entirely. There can be no difference of opinion on this fact, 
 therefore the best equipment is the personal knowledge which makes 
 one independent of any appliance or set of rules and regulations. It 
 is generally contended that exposing the eye to such severe changes of 
 light is injurious, and this may be true beyond a certain point, viz., 
 2300° r., a temperature sufficient for the majority of our porcelains. 
 There is a product by a well-known firm which requires a heat of 
 2600° F., and there is no doubt that the eyes should be protected 
 from the glare of this heat, which is unnecessarily high, especially for 
 inlay work. 
 
 As electric furnaces are most commonly used for fusing porcelain, it 
 is not very difficult for the student to become familiar with the various 
 changes of heat as regulated by the rheostat, and thereby know what 
 step will fuse a certain known product. For instance, the first step 
 on the majority of furnaces will fuse a low fusing body of 1600° F. in 
 probably one minute or even less, but the same heat will fuse a much 
 higher porcelain if given longer time. Then again, voltage must be 
 considered, for in many cases it is only approximate, sometimes vary- 
 ing three or four points less or that much more, and still coming under 
 the class of 110 volts direct. This fact is particularly noticeable in 
 local establishments such as office buildings. The alternating current 
 is usually more even, that of 220, however, being very strong and 
 harder on the furnace muffles. 
 
 The best fusing is obtained by inserting the porcelain at the lowest 
 temperature and gradually and slowly raising the heat until the fusing 
 point is obtained, thus passing the material through its various stages 
 of condensation. These stages are called "biscuiting," and a porcelain 
 partially fused may be called a medium or hard biscuit. In the latter 
 condition the porcelain has a half glaze and has shrunk to a solid mass 
 
FURNACES 329 
 
 and is ready for the additional material required to give form. Then 
 the porcelain can be fired until it has the finished gloss, which is 
 determined by the eye of the manipulator. The best results are always 
 obtained by underfusing the first bake, because several high heats will 
 overfuse the groundwork which reduces its strength and solidity. 
 Using a porcelain of slightly lower fusing point the finishing will obviate 
 this tendency, which is detrimental to the whole work. 
 
 As an instance of this, note a manufactured tooth which is finished 
 in one baking, and the same directions are applicable to carved teeth 
 for special cases. A student will readily learn the proper glaze 
 required if he will take any plain or plate tooth and apply porcelain to 
 its surface and watch the various changes until his material has reached 
 the same condition. This simple experiment will also help him to 
 recognize the heat required for these changes and ultimately enable 
 him to acquire self-confidence in the management of the fusing process. 
 
 Porcelain. — Porcelain bodies made for inlay purposes are to be had 
 in great variety, both in fusing point and texture; in fact, there is such 
 a number for choice that the unexperienced must necessarily be 
 bewildered. 
 
 However, this difficulty will settle itself like many others that may 
 at one time have been just as perplexing. 
 
 FURNACES. 
 
 The advancement in the matter of furnaces has been so rapid that 
 less than thirty years ago the user of porcelain depended on such an 
 apparently crude appliance as is shown in Fig. 336 (old coke furnace), 
 and yet the beautiful porcelain dentures and carved work of the older 
 dentists have not been surpassed. 
 
 It was early recognized that a small, quick heating appliance was a 
 necessity, and this difficulty was solved by Dr. C. H. Land by inventing 
 the first gas furnace in 1886. This machine, while a great improve- 
 ment, was slow and tiresome, as the constant use of bellows was neces- 
 sary for half an hour before the furnace was hot enough for use. A 
 smaller and quicker gas furnace succeeded this, more applicable for 
 inlays and crowns, and was successfully used until superseded by 
 electrical outfits, which have the advantage of cleanliness, purity, and 
 noiselessness. 
 
 A gas furnace is noisy and gives much trouble in carbonizing the 
 porcelain, or as it is usually termed "gassing." Fortunately, that is a 
 discouragement of the past, for electricity has reduced fusing cares to 
 the minimum. Other furnaces of that time were the Parker-Stoddard, 
 Downie, and Fletcher. 
 
Fig. 334. — Custer No. 1, for crown, bridge and inlay work. 
 
 Fig. 335. — Custer, No. 2, for crown, bridge, inlay and continuous gum work. 
 
FURNACES 
 
 331 
 
 Dr. L. E. Custer invented the first electric furnace in 1894, and 
 while it was a distinct improvement, there was much trouble in muffle 
 wires burning out, which caused much delay and retarded the general 
 
 Fig. 336.— Old style coke 
 furnace. 
 
 Fig. 337. — The Hammond furnace No. 1. 
 
 Fig. 338. — ^S. S. White furnace with pyrometer attachment. 
 
332 HIGH FUSING PORCELAIN INLAYS 
 
 use of this class of furnace. The Custer electric furnaces (Figs. 334 and 
 335) as now perfected are practically useful and are strong favorites. 
 Five years later the Hammond was patented, and immediately became 
 popular from the fact that a "damaged" muffle could be replaced 
 immediately. 
 
 This furnace has remained a favorite until the present time, but is 
 being gradually replaced by the S. S. White Co.'s new furnace (Fig. 338), 
 which is similar, but improved in certain details, and it is also arranged 
 with pyrometer attachment. 
 
 In 1902 the Pelton appeared. Besides these furnaces there are sev- 
 eral others distinct in form, and all, with few exceptions, have a pyro- 
 meter attachment. They are: the Fletcher, Peck, Gerhardt, and 
 Roach, and others including the Price, which has been withdrawn, 
 although Dr. Price was the first to apply the pyrometer. 
 
 In addition, furnaces are also made for gasoline use. The principal 
 types are the Turner and Brophy. They are of great value to the 
 out-of-town dentist, because they not only fuse porcelain, but have 
 equal facility in blowpipe work and metal heating, thus enabling" 
 those not possessing gas or electricity to be practically on the same 
 footing with the city practitioner. 
 
 PRODUCING PROPER COLORS IN PORCELAIN INLAYS. 
 
 The pigments most commonly used in the manufacture of dental 
 porcelains are precipitated gold and platinum, purple of Cassius and 
 the oxids of gold, titanium, manganese, cobalt, iron, uranium, silver 
 and zinc. The colors produced by the use of these pigments in varying 
 proportions are red, yellow, blue, green, brown and gray. Red is not 
 used extensively by inlay workers. All gum enamel frits are tints of 
 red. It may be used in the manufacture of browns and grays, also to 
 build the gingival portion of many inlays. 
 
 Yellow. — ^Yellow is the most important color for the porcelain 
 worker. It is used to form the body of most inlays; it adds brilliancy 
 to the browns or grays when combined with them. Yellows of a greenish 
 hue tend to lose their luminosity in yellow light. Two yellows, in their 
 deeper tones, may match each other perfectly, but when diluted to 
 give hghter tints, may differ quite widely. One may be of a greenish 
 hue, while the other may tend toward a grayish. 
 
 Blue. — ^This color is used to build the body of the incisal or occlusal 
 portion of inlays for those teeth with blue incisal edges or cusps. There 
 is a variation in tone from greenish blues to those of a reddish hue. 
 Blues of a greenish hue appear to be more translucent. 
 
PRODUCING PROPER COLORS IN PORCELAIN INLAYS 333 
 
 Other Colors. — Green is seldom used alone, it may be added to blue 
 to increase its translucency. Browns are used to build the gingival 
 portion of some inlays and for the body of inlays for discolored teeth 
 with a brownish hue. They may be added to yellows to modify them. 
 Grays are used to build the middle and incisal or occlusal portions of 
 many inlays. They are also used to tone yellows and blues. 
 
 Shading. — This part of making porcelain inlays is the most difficult 
 to the majority, and is an uncertainty with all of us. The problem 
 of shrinkage is an unknown quantity, and its remedy is purely mechan- 
 ical, but the problem of shading is a combination of various considera- 
 tions which may be followed most minutely and then the object may be 
 defeated by some detail not always possible to avoid, and this most 
 common defect is caused by the opaque cements. The most experi- 
 enced have this discouragement, but it can be decreased by using a 
 variety of shades and matching carefully. We have and can mix an 
 almost endless variety of porcelain shades, but this is only a part of the 
 requirement, for position and tooth density must also be considered, 
 together wdth quantity of porcelain to be fused. There is also the 
 additional difficulty of correct fusing to reproduce the desired shade. 
 
 Overfusing is the cause of more shade failures than any other, but 
 practice will largely obviate this trouble as in other difficulties. The 
 most careful directions are inadequate as compared with actual demon- 
 strations. After all has been said, there is still the possibility of 
 failure to appreciate this phase of the work, because this part of it 
 appeals directly to the artistic sense, and can only be comprehended 
 through observation and experience. 
 
 The difficulty of obtaining colors that accurately match the natural 
 teeth is a part of inlay w^ork w^hich will always be perplexing, for the 
 teeth are largely composed of organic matter, while the material used for 
 repair is an inorganic composition, differing in texture and density. 
 When selecting the colors for inlays, note the various shades of the 
 natural tooth, for frequently there are three or more. If the tooth is 
 vital these hues have a distinction which is lost after devitalization, 
 thus increasing the difficulties of matching, but if the variant and 
 uncertain hues of the pulpless tooth are once reproduced in an inlay, 
 the subsequent change attending the cementation is not so marked 
 because of the pulpless tooth opacity. 
 
 Position of the inlay is a factor which largely governs the shade, for 
 the shadow problem is an incident which forces consideration also. 
 This is particularly evident in proximate cavities, aud is remedied to 
 some extent by making the inlay a shade lighter, and is also controlled 
 by the size of the inlay. A lateral incisor being much smaller than a 
 cuspid must be treated accordingly, for the density of the latter is much 
 
334 HIGH FUSING PORCELAIN INLAYS 
 
 greater and will allow a deeper shade. Labial inlays, particularly 
 bordering the gingival line, can safely be made a shade deeper; but 
 due consideration must be given to depth, for if very shallow, the por- 
 celain should be of greater density and thus overcome the cement 
 change. Inlays of this kind are improved in texture by using nearly all 
 base body, and in some instances low fusing porcelain is more effective 
 because of its less translucency. 
 
 With one exception all inlay porcelains are of the same texture from 
 base to finish, which is an advantage in the instance just cited, but the 
 introduction of a combination consisting of a basal body to be covered 
 by enamels was a step toward procuring more natural results in the 
 majority of cases. This basal body represents the dentin, which in 
 turn is covered by a more transparent material representing the enamel, 
 thus enabling the operator to blend the various hues of shade of which 
 the natural tooth is composed, thereby producing a translucent effect 
 not possible by one dense porcelain no matter how expert the operator 
 may be. 
 
 The restoration of an incisal tip or corner is an operation that requires 
 much practice and artistic skill, for its prominence demands perfect 
 shading and adaptation. An operation of this character, while testing 
 the ability to shade, has the advantage of not being affected by the 
 cement line because of greater proportion or volume of porcelain. How- 
 ever, perfection must not be expected because there is always the differ- 
 ence between the natural translucency of tooth structure and the 
 unavoidable density of porcelain which in certain positions is more 
 noticeable by the deflection of light rays. 
 
 A common mistake in shading is in not considering the difference 
 between the volume of shade exposed on the porcelain shade guide and 
 the quantity required to fill the cavity. 
 
 The mixing of several shades to gain the one desired is largely one of 
 intuition, because that shade cannot be known until properly fused. 
 This difficulty is unfortunate, but cannot be avoided, as all porcelain 
 powders are practically the same, with the exception of a few extreme 
 shades, and herein lies the difference between the porcelain artist and 
 the painter whose pigments are mixed and the desired shade revealed 
 to the eye by simple manipulation. 
 
 CEMENTS AND MANIPULATION. 
 
 It is generally conceded by porcelain operators that while a material 
 of this kind is almost an ideal filling, it falls short of the ideal because 
 W? are forced to use as an attachment a substance detrimental to that 
 
CEMENTS AND MANIPULATION 335 
 
 aim which we have in view, namely, the absolutely invisible restora- 
 tion of tooth form. 
 
 What cement do you use? is an ever-present query in all porcelain 
 discussion, for when there is a failure the cement is generally blamed 
 for it. This is a natural deduction when it is considered that a student 
 in porcelain is more familiar with cement than with other parts of the 
 operation, and if there is a failure it is a natural supposition that it is 
 caused by poor material. A cement must be tenacious, finely ground, 
 and not quick setting, and of a quality most likely to resist moisture 
 when setting, for it is not always possible to keep the work free from 
 dampness during that important stage. There are many cements 
 manufactured that have these requirements, and, like other materials 
 with similar merits, the choice rests with the operator. They all have 
 the same disadvantage, viz., opacity, and the perfect porcelain opera- 
 tion cannot be claimed until the attaching medium is transparent, or 
 nearly so. A common trouble is mixing cement too thick, thus pre- 
 venting proper seating of inlay, which makes the joint conspicuous and 
 unfinished. When this occurs, quickly remove and cleanse every part 
 thoroughly, replacing with a thinner mixed material. 
 
 As already stated, a filling of porcelain can be made perfect in shape 
 and shade and the texture may approximate tooth substance in a 
 highly satisfactory manner; but immediately upon attaching it per- 
 manently the shade is changed through the differences between the 
 three substances, all of different density, which come in close contact, 
 namely, porcelain, cement, and tooth. The cement being the chief 
 point of difficulty, it is important that its objectionable features should 
 be reduced to the minimum. 
 
 It is a poor cement that is not at least preservative. Many cements 
 are similar in manipulative qualities with the difference of slow, medium 
 and quick setting tendencies. Some are coarse and others are fine, and 
 a few have a combination of many good qualities but with that ten- 
 dency to "pack" under pressure which causes annoyance to porcelain 
 workers. A cement closely ground, of clear color and medium to slow 
 setting, having the maximum adhesiveness with the least amount of 
 powder, is what is recommended for a successful operation; add to this 
 one that has the greatest amount of resistance to moisture during what 
 is usually called the "setting" period. 
 
 Shading a cement to match the tooth, or to lighten or darken either 
 the porcelain or tooth, or both, is quite bothersome at times and dis- 
 appointing also. It is of considerable assistance to mix pellets of cement 
 of a variety of shades and mount them in the most convenient manner 
 to allow of comparison, in that way saving much time and avoiding 
 guess-work. Whenever possible use the deepest yellow because pur^ 
 
336 HIGH FUSING PORCELAIN INLAYS 
 
 calcined oxid of zinc is quite yellow, and its chemical combination with 
 phosphoric acid is more complete than when otherwise changed.^ 
 
 For instance, a white or very light yellow is made so by oxid of zinc, 
 thus reducing the chemical union to a marked degree; and the same 
 applies to darker shades, such as browns, blues, and grays. This is a 
 point of some advantage in setting crowns and bridges, or whenever 
 tenacity is a first requirement; for such purposes use the purest yellow 
 cement just as it comes from the bolting cloth without the slightest 
 manipulation whatever. 
 
 Some years ago there was invented by Dr. C. H. Land a material in 
 the form of a paste or paint which is applied to that part of the porcelain 
 intended for attachment, and which is then subjected to heat of about 
 2000° F., thus giving the porcelain a semi-vitrified surface composed 
 of a substance which has a chemical affinity for cement and acts 
 as a medium of attachment. This promises to be of most important 
 assistance in many cases wherein strength is of first consideration. This 
 material is called "Media" and is made for both high and low fusing 
 porcelain, and will also be found of value in repairing facings of broken- 
 crowns and bridges. It is claimed that by its use added strength is 
 given to porcelain, enabling the operator to extend the field of porcelain 
 work to all masticating surfaces or other places where the strain is too 
 great to use porcelain with cement as the only attachment. I am 
 prompted to mention this article at this time, because I am interested 
 in any and everything pertaining to this branch of dentistry that may 
 seem to promote its advancement, and also because I have privately 
 and publicly made tests sufficient to give confidence in its merit and 
 convince me that its use will be general when once its advantages are 
 known. 
 
 UNDERCUTS FOR RETENTION PURPOSES. 
 
 Undercuts are not necessary in the tooth cavities, but they are 
 imperative in the filling for retentive purposes, and are made with 
 diamond or hard rubber and corundum disks. The latter are made in 
 such a variety of shapes and sizes that I think they are all that can be 
 desired, for their cutting power is equal to any other and the cost very 
 moderate. Some dentists claim that cuts in the porcelain are not 
 necessary, as hydrofluoric acid will roughen the surface sufficiently to 
 stand any strain and that cutting of porcelain is a source of M^eakness 
 which is not occasioned by using acid. This may be so if the undercuts 
 are made too near a wearing surface, but again experience is our test 
 
 1 The reader is referred to the subject of cements, Chapter YII, for a further discus- 
 sion of this subject. — Editor. 
 
UNDERCUTS FOR RETENTION PURPOSES 337 
 
 and that is much in favor of undercuts. In very small inlays acid can 
 be used to advantage, and it cannot be a disadvantage to use it in con- 
 nection with undercuts, but to stake your trust entirely on the use of 
 acid is a mistake which will cause trouble. 
 
 The method of using it on very small inlays where an undercut is 
 impossible, is to soften the surface of a piece of beeswax or paraffin and 
 embed the porcelain, taking care not to have edges exposed, then drop 
 a little acid on the exposed surface and allow it to act for a few minutes ; 
 then wash off with a water syringe. 
 
 Placing the porcelain in position is a part of this work that requires 
 extreme care and frequently great patience. Care should be observed 
 that the cavity is thoroughly dry before the insertion of the filling 
 and kept dry until the cement is hard enough to resist moisture. Use 
 alcohol freely in the cavity and on the filling; then apply hot air and 
 mix the cement to a creamy consistence; this, when applied to the 
 cavity walls, almost grows there, the afiinity is so great. As quickly as 
 possible place the inlay and gently press into position and hold until it 
 becomes fixed. The excess of cement is removed by a small piece of 
 firm spunk. In proximate work I use waxed silk, drawn over the surface 
 gently working from center to edges, for in this way excess cement is 
 easily taken from between the teeth, which, if left until hardened, may 
 loosen the filling in removing it. It is risky to try to get everything 
 clean, much better to leave the surfaces a little smeary. For protection 
 against saliva the parts should be covered with a little hot paraffin. 
 Rubber and sandarac varnish and chloropercha are used by some, but 
 paraffin is the favorite because it is cleaner and has a blending effect 
 which is quite an advantage at that time, for the tooth is lighter by the 
 drying process and the cement has given the porcelain a more opaque 
 appearance; so it is just as well that the patient should not be allowed 
 to inspect the result too closely just after the insertion of the filling. 
 The time to show it to the patient is before the tooth is dried; put the 
 filling in its place and allow the saliva to be the cement for the time 
 being. Frequently it is never seen to better advantage. 
 
 At a subsequent sitting the edges are touched with a stone, and the 
 most expert operator will find this necessary, for the tongue will find 
 an edge if he cannot. Fortunately for us, after a time there is a blending 
 of the porcelain and tooth that is quite gratifying; but it is better to 
 explain this to the patient, for some people are unreasonable enough 
 to expect perfect results with very imperfect agencies. The difficulties 
 besetting a porcelain worker are growing less each year because when 
 a thing is demanded and that demand comes through confidence, then 
 allowances are made which will assist the operator provided he has 
 skill and is tactful. 
 22 
 
338 HIGH FUSING PORCELAIN INLAYS 
 
 Cementation of Inlays with Silicate Cements. — The attachment of 
 inlays with siUcate cement greatly adds to the beauty and complete- 
 ness of the inlay, but its use is governed by certain conditions. This 
 cement is not so adhesive to the tooth structure as oxyphosphate, 
 therefore a decided undercut in the cavity is absolutely necessary. The 
 silicate cement will adhere to the porcelain with small assistance and 
 apparently has all the adhesiveness necessary in the cavity, but after a 
 time, probably a few months, this tenacity is diminished, rendering 
 an undercut a necessity. This condition is a reversal of the qualities 
 of the older cements and may be remedied in the future, thereby over- 
 coming the "cement line" objection. A porcelain inlay well shaded 
 and adapted, then attached with a silicate cement, is a perfect restora- 
 tion. . 
 
CHAPTER VII. 
 
 PROPERTIES OF FILLING MATERIALS. 
 
 By MARCUS L. WARD, D.D.Sc. 
 
 Introductory. — The chapter on properties of filling materials is 
 written as a separate chapter in order not to break the continuity of 
 thought that a student or practitioner of dentistry has when engaged 
 in a study of the operations described in the chapters dealing with the 
 practice of dentistry. This chapter is intended to be more a corre- 
 lation of the more important data on the physical and chemical proper- 
 ties of materials used in the practice of dentistry than a treatise on 
 practice. It appears to have been customary in former years to omit 
 data of this nature from text-books on operative dentistry and to refer 
 the readers of such work to text-books on metallurgy, which, in most 
 instances, have not treated the subject with specific reference to oper- 
 ative dentistry. This practice on the part of editors seems to have be- 
 come antiquated, for it has been tried long enough to have produced 
 better results if it had possessed much merit. It is hoped, therefore, 
 that the manner of treating the subject and the close promixity of 
 the data in question to the data on the more practical part of dentistry 
 will result in a better understanding of the materials that are in so gen- 
 eral use. Gold is treated comparatively briefly because the use of all 
 the available data on it does not seem warranted in a text-book on 
 operative dentistry, and because students of dentistry usually receive 
 more instruction on this subject than on most others. The subject of 
 amalgam has included in it a discussion of the subject of manipulation 
 because many of the properties depend so largely upon the manipu- 
 lation. Porcelain has been omitted from the list of materials con- 
 sidered, primarily because the data concerning it are largely in the 
 hands of the manufacturers and secondarily because the compara- 
 tively limited knowledge of the subject is well covered in Chapter V. 
 
 GOLD. 
 
 Gold is one of the first metals with which man became acquainted. 
 As a result of this an appreciable amount of data has accumulated, 
 
 (339) 
 
340 PROPERTIES OF FILLING MATERIALS 
 
 for from the first gold has attracted much attention because of its 
 wonderful properties and intrinsic value. In the search for gold, 
 men have endeavored to produce it by the transmutation of base 
 metals, and in doing so have made many discoveries which have 
 probably aided in laying the foundations for the science of metallurgy. 
 It is doubtful if the metallurgy of some metals would have been as 
 well developed if it had not been for the work done on gold. On 
 account of the part it has played in the development of metallurgy, 
 its intrinsic value and wonderful properties, gold has been termed the 
 most noble of metals. A solid mass of pure gold is yellow in color, 
 but when finely divided, as it is when volatilized, or when precipitated 
 from solution it may be violet, ruby, purple or brown in color. Com- 
 mon examples of violet gold are seen when the oxyhydrogen blow-pipe 
 has been used to melt gold for casting purposes, the gold having col- 
 lected around the edges of the cold casting ring. Examples of brown 
 gold may be observed in the various sponge golds in the market for the 
 purpose of filling teeth. If a very thin sheet of gold be supported upon 
 a glass plate, it appears green, on account of transmitted light. If the 
 plate containing the gold be heated to 250° C. it will appear white, due 
 to the formation of aggregates of gold between which the light 
 passes. Various colored golds may be produced by alloying with 
 other metals.^ 
 
 Gold possesses a very high specific gravity. SchnabeP gives the 
 specific gravity of gold as follows: 19.30 to 19.33 at 17.4° C. after it 
 has been fused and cast. Rose^ gives it as 19.33 to 19.34 when it has 
 been compressed and 19.55 to 20.72 when precipitated by ferrous 
 sulphate. Hoffman^ lists gold along with other metals in a table to 
 show the effect of rolling and hammering upon specific gravity. His 
 figures are 19.25 for cast gold and 19.35 for hammered gold. The 
 specific gravity of fillings made from foil varies between 14 and 18 for 
 good operators. 
 
 The melting-point of gold is usually given by dental authorities 
 above 2000° F. and by metallurgical authorities as 1063° to 1065° 
 C. The most reliable authority, however, gives it as 1064,4° C. 
 (1947.92° F.) 
 
 The approximate melting-points of the various gold products of 
 the J. M. Ney Company are published by this company according to 
 the table on the opposite page. 
 
 1 For a discussion of this subject the reader is referred to the various works on metal 
 coloring. 
 
 2 Handbook of Metallurgy, vol. i. ' Metallurgy of Gold. 
 4 General Metallurgy. 
 
GOLD 341 
 
 Degs. Fahrenheit. Degs. Centigrade. 
 
 2200 Ney-Oro gold plate No. 3 1204 
 
 2100 Ney-Oro "elastic" gold 1150 
 
 2075 Ney-Oro gold plate No. 1 1135 
 
 1975 Ney's high fusing clasp metal 1080 
 
 1975 Ney-Oro gold plate No. 2 1080 
 
 1960 Ney-Oro casting gold "E" 1070 
 
 1945 Ney's pure gold (24 k.) ' 1063 
 
 1945 Ney-Oro casting gold "A" 1063 
 
 1940 Ney's green backing 1060 
 
 1900 Ney-Oro casting gold "B" 1035 
 
 1900 Ney's light 22 k. plate 1035 
 
 1825 Ney's dark 22 k. plate ; 1010 
 
 1800 Ney-Oro casting gold "C" 980 
 
 1735 Coin gold (U. S. standard) 946 
 
 1735 Ney-Oro casting gold "F" 946 
 
 1725 Ney's regular clasp metal 940 
 
 1675 Ney-Oro gold solder No. 84 915 
 
 1625 Ney's gold solder for 22 k 885 
 
 1550 Ney-Oro gold solder No. 76 840 
 
 1525 Ney's gold solder for 20 k 820 
 
 1450 Ney-Oro gold solder No. 68 785 
 
 1425 Ney's gold solder for 18 k 770 
 
 The gold products of the S. S. White Company have approximately 
 the following melting-points according to this company's statements: 
 
 Melting-point. 
 Degree Degree 
 
 Metal. F. C. 
 
 Plates and Wires: 
 
 18 k 1740 949 
 
 20 k 1729 943 
 
 No. 1 clasp 1850 1010 
 
 No. 3 clasp 1760 960 
 
 Plates: 
 
 18 k. light 1895 1035 
 
 Coin 1706 930 
 
 22 k. dark 1859 1015 
 
 22 k. light 1913 1045 
 
 Solders: 
 
 For 14 k. . 1360 738 
 
 16 k 1441 783 
 
 18 k 1470 709 
 
 20 k 1521 827 
 
 Coin 1567 853 
 
 22 k 1578 859 
 
 The boiling-point of gold at atmospheric pressure is approximately 
 2200° C. The volatility of gold is given by Schnabel as very little at 
 1045° C. and barely appreciable at 1075° C. He states, however, that 
 at 1250° C. it is four times greater than at 1100° C. The specific heat, 
 or ratio between the heat required to raise the temperature of water 
 and metal 1° is given as 0.030 to 0.032. 
 
 Ductility, or the property of gold to extend by traction as compared 
 with some of the common metals, is as follows: gold, silver, platinum, 
 iron, nickel, copper, aluminum, zinc, tin, antimony. It is stated that 
 one grain of gold can be drawn into a wire 160 yards long and can be 
 
342 PROPERTIES OF FILLING MATERIALS 
 
 beaten into a sheet T^oViTTr of an inch thick. Schnabel states that 
 Reaumur succeeded in producing a sheet 0.00000087 of an inch thick. 
 
 Malleabihty, or the property of being extended in all directions 
 without cracking when rolled or hammered, is shown to be in the same 
 position as ductility with the order of the other metals somewhat 
 changed. It is as follows: gold, silver, aluminum, copper, tin, platinum, 
 lead, zinc, iron, nickel. 
 
 The hardness of gold as compared with some of the other non-ferrous 
 metals is given in hardness numbers on a Brinnell hardness testing 
 machine as follows: 
 
 Copper 74.00 
 
 Silver 59.00 
 
 Antimony 55.00 
 
 Gold 48.00 
 
 Zinc 46.00 
 
 Aluminum 38 . 00 
 
 Tin 14.00 
 
 The hardness of gold and the principal alloys of gold in use in 
 dentistry were recently tested with a Shore Scleroscope and found to 
 be as follows:^ 
 
 Hardness of Various Dental Golds. 
 
 Each of the valaes is the average of ten readings on a Shore Scleroscope. 
 
 Ney's Ney's Ney's Ney's Ney's Ney's Ney-Oro S.S. White 
 
 24 k. 22 k. 22 k. 20 k. 22 k. 20 k. 18 k. "E" clasp 
 
 L. C. D. C. plate. solder, soder. solder. clasp metal. 
 
 metal. 
 
 Cast ... 4.9 5,5 12.5 18.3 25,4 33.8 59.8 25.4 37.9 
 
 Rolled . . . 33.0 45.2 52.0 70.7 73.9 79.1 80.7 86.5 80.4 
 Annealed^ after 
 
 rolling . . 5.8 6.4 14.3 22.5 30.8 39.9 42.9 50.9 41.2 
 
 The hardness of a metal varies with the treatment given it. The 
 hardness values of the common dental golds are shown in the table to 
 be high when rolled or hammered, low when cast and somewhat between 
 the two when annealed after rolling or hammering, with the exception 
 of 18-carat solder. As a rule, metals are soft when cast and hard when 
 rolled or hammered. Alloys, especially the more complex ones, do 
 not follow this rule but may be either hard or soft when cast. A good 
 example of this is shown in the softness of the clasp metals, which are 
 soft when cast, and the 18-carat solder, which is hard when cast, both 
 of which contain four metals. (See paragraph on annealing.) 
 
 The rate of cooling may cause the hardness of a metal to vary, and 
 usually has a marked effect upon the hardness of alloys. The author 
 recently subjected the various golds shown in the table to different 
 
 1 These tests were made for this chapter by Marcus L. Ward and E. O. Scott. 
 
 2 The annealing was done by heating to redness and quenching. 
 
GOLD 343 
 
 rates of cooling and found that the practice of dentists of heating to 
 redness and quenching produced the results desired in the higher carat 
 golds and solders, but as the 18 and lower carat solders and clasp 
 metals were reached the results were very irregular. In fact, they 
 were so irregular that it seemed inadvisable to publish them until they 
 could be confirmed with further work. It seems, therefore, in order 
 to obtain the desired properties from the complex alloys, such as the 
 solders and clasp metals, that research work on cooling is necessary 
 for each one of them and that instructions should be given for the 
 cooling of such products. 
 
 The term hardness may often be taken as synonymous with strength. 
 This is not always true, however, for the term hardness is used to 
 express at least five ideas: resistance to scratching, to indentation, to 
 elastic impact, to cutting and to permanent deformation, and the 
 term strength is used to define resistance to at least five forces, as 
 follows: forces which fracture, twist, pull, compress and change 
 shape. A good illustration of hardness without toughness or proper 
 resistance to all stresses is the hardness of the minerologist, as follows: 
 showing ten minerals in the order of their hardness: talc, gypsum, 
 calcite, fluorspar, apatite, feldspar, quartz, topaz, corundum and the 
 diamond. 
 
 Metals or alloys which are as hard and brittle as these materials 
 would be of little use in dentistry, for they would not resist the forces 
 of mastication. Whenever the terms hardness and strength are used 
 synonymously, therefore, it should be understood that strength implies 
 both hardness ard toughness. 
 
 Gold which has been hardened by rolling or hammering may be 
 softened by annealing, which is usually done by heating the gold to 
 redness and quenching in hydrochloric acid (50 per cent, or more) or 
 in sulphuric acid of the same strength. The former is preferred by 
 many for the reason that it is not so destructive to linen or clothing 
 with which it may come in contact. It is not accessary to heat gold 
 to redness in order to anneal it. It has been shown^ that if gold is 
 heated to 150° C. and held at this temperature for thirty minutes or 
 longer it will become quite well annealed. Other metals may be 
 annealed at comparatively low temperatures if the heat be main- 
 tained for a long time, and like gold will be annealed more completely 
 and quickly with slight vibration in connection with the heat. The 
 maaner of annealing the complex alloys, as has been stated, is not 
 known. Dentists usually give them the same treatment as pure gold, 
 though it seems likely that investigation will show this practice to be 
 
 ^ Rose, Institute of Metals, 
 
344 PROPERTIES OF FILLING MATERIALS 
 
 erroneous in some cases. In this connection it may be stated that 
 Gulliver^ and others refer to the hardening of steel by quenching and 
 the softening of bell metal by the same treatment. When a pure metal 
 is chilled rapidly from a molten condition about the only difference that 
 is observed from the normal structure is the smallness of the grains. 
 This is because the number of centers of crystallization have been 
 increased. If, on the other hand, the metal is allowed to cool more 
 slowly the centers of crystallization are fewer in number ^nd the 
 metal appears more coarse-grained. This, obviously, will alter mark- 
 edly the physical properties of some metals and most alloys. 
 
 The tensile strength of gold is given by Hoffman as 37,000 pounds 
 per square inch for hard-drawn wire and 24,000 pounds per square 
 inch for soft-drawn wire. It is probable that these figures refer to 
 unannealed and annealed drawn wire. Hiorns gives the tensile strength 
 of gold as 7 tons per square inch, but does not state whether it is 
 annealed or unannealed. It is strange that more work has not been 
 done on the strength of gold. Perhaps the figures available are quite 
 accurate. It appears, however, that they hardly represent the differ- 
 ences that should exist between the annealed and unannealed metal. It 
 is not strange that compression tests have not been made on gold, for 
 with gold as with many metals there is no definite crushing point under 
 compressive stress, as is the case when metals are subjected to a tensile 
 or traction test. When some metals are subjected to a compressive 
 stress they simply spread when the elastic limit has been reached. 
 Inside of this point they return to the original form after the load is 
 removed. With other metals, however, and with some alloys, when the 
 elastic limit is reached there is a definite breaking-point. Amalgams 
 furnish a good example of the common alloys which have quite definite 
 breaking-points and for which a compressive stress test is preferable 
 to a tensile stress test. 
 
 Gold has a coefficient of linear expansion for 1° C. between 0° and 
 100° of 0.0000144. In general, when heat energy is added to a body 
 its volume changes. Volume change is known as cubical expansion. 
 In the discussion of expansion and contraction, however, one dimen- 
 sion is usually all that is considered. This is along a linear dimension 
 of the body and is known as linear expansion. The coefficient of expan- 
 sion increases with increases in temperature and is quite marked near 
 the melting-point. It also varies with the physical condition of the 
 metal. An operation which increases the density will also increase the 
 expansion. It is a general rule that all metalfe expand when heated and 
 contract when cooled. There are one or two exceptions, however. 
 
 1 Metallic Alloys. 
 
GOLD 345 
 
 Copper, bismuth and antimony are among the metals claimed to 
 expand while cooling. It is claimed that copper expands while cooling 
 only under conditions which have been favorable to occlusion and dis- 
 solving of gases which are expelled during the cooling process. For 
 bismuth and antimony, however, no explanation seems to have been 
 made which would account for the phenomenon of expansion when 
 cooling. Coefficients of expansion and contraction are for given tem- 
 peratures only, for as the melting-point of most metals is reached the 
 volume is decidedly increased. 
 
 Shrinkage being the reverse of expansion may be estimated by the 
 expansion, as a general rule. Shrinkage, therefore, is very marked as 
 the metal changes from the liquid to the solid state and corresponds 
 to the expansion at other temperatures than the ones which bring it 
 to a liquid state. It would be interesting to know the coefficient of 
 volume change for gold at its liquefying point, for with the advent of 
 the casting process into general use it is necessary to fill molds of every 
 conceivable shape with gold or gold alloys in order to meet the demands 
 of modern dentistry. The only research that has been done to deter- 
 mine the shrinkage of gold in casting it into molds would lead one to 
 believe that it was about 2 per cent. The absence of some very essen- 
 tial data in connection with this work makes it of little value. It is 
 probable, however, that the total shrinkage of gold from a state of 
 fluidity which would permit the filling of a mold for a filling is somewhat 
 above 1 per cent., depending upon the temperature of the gold when 
 it is forced into the mold. Many operators make the mistake of casting 
 gold at or near its boiling-point, at which the gold is in a very much 
 expanded condition, and, consequently, must result in an excessive 
 shrinkage. 
 
 Numerous theories have been advanced by practitioners of dentistry 
 about the excessive shrinkage of gold under certain conditions. It is 
 probable that too much heat has been used or the gold has been 
 alloyed with something which results in excessive shrinkage. It should 
 be remembered that the volume change of many alloys, especially the 
 complex ones, cannot be calculated. Metals are subject to volume 
 change from changes in temperature, but alloys have volume change 
 from changes in temperature and from the reaction between the con- 
 stituent metals which cannot be calculated. 
 
 Pure gold can be welded in a cold state. Ordinaril}^ welding is accom- 
 plished by bringing the metals to a temperature that makes them pasty 
 when the motion of the molecules is so accelerated that they inter- 
 penetrate or diffuse into one another when slight pressure is applied. 
 In heating readily oxidizable metals it is necessary to exclude the air 
 or use fluxes which will slag any oxids formed and form a somewhat 
 
346 PROPERTIES OF FILLING MATERIALS 
 
 impervious coating. Inasmuch as gold does not oxidize under ordinary 
 conditions, or have the ordinary contents of the air condense upon its 
 surface, it may be welded in a cold state. There are certain gases, 
 however, which do combine with and condense upon the surface of 
 gold and prevent both cohesion and welding. The following are said 
 to be capable of condensing upon the surface of gold to such an extent 
 that its cohesion and welding are impaired: carbon dioxid, sulphur 
 compounds, iodin, the various oils used in dentistry and other volatile 
 substances. Chlorin is said to combine with gold sufficiently when con- 
 densed upon the surface in the form of ammonium chlorid to prevent 
 cohesion and welding. It is claimed by some that, as a result of this 
 action, ammonia has been adopted for condensation upon the surface 
 of pure gold to make cohesive gold non-cohesive. 
 
 The thermal conductivity^ of gold is 53.20, copper being 73.60 and 
 silver 100, according to Hoffman. The electric conductivity of gold 
 has been given by Matthiessen as 77.96, copper as 99.95 and silver as 
 100, all of which were drawn metal. Cast metals are poorer con- 
 ductors than those which have been hardened by drawing, hammering 
 or rolling. Conductivity may vary with purity and temperature. 
 
 Gold in solid form is said to absorb gases when heated to redness 
 and in spongy form at ordinary temperatures (Schnabel). Some other 
 writers claim that gold is an exception to the general rule that molten 
 metals absorb gases and does not absorb an appreciable amount. The 
 conclusion that seems to be warranted is that the subject is not well 
 understood at the present time. 
 
 Gold is not soluble in a single acid except selenic (Il2Se04). It is 
 soluble in aqua regia on account of the chlorin available. Gold is 
 readily dissolved by chlorin or any substance which yields chlorin. 
 Gold may be precipitated by organic substances, several gases, most 
 metals and by some metallic salts. 
 
 Gold does not oxidize either at the ordinary temperatures or at 
 elevated ones. Two oxids of gold are claimed to exist, however, 
 aureus oxid, AU2O, and auric oxid, AU2O3. The former results when 
 mercurous nitrate and neutral auric chlorid are put together or by 
 treating aurous chlorid or bromid in the cold with caustic potash. The 
 latter is obtained when auric chlorid solutions are treated with some 
 alkaline substance. Gold is not acted upon by sulphur and sulphur 
 compounds in the same manner as most metals are. With free sulphur 
 it does not combine at all and with hydrogen sulphid it does not appear 
 to combine except when the hydrogen sulphid is introduced into solu- 
 tions of gold. Gold alloys readily unite with other metals, sometimes 
 forming definite chemical compounds. 
 
 From the foregoing it is clear that gold is one of the most perfect of 
 
GOLD 347 
 
 the metals, but it is necessary to impart to it a greater degree of strength 
 than it alone possesses, for the manufacture of jewelry, coins and many 
 dental restorations. 
 
 Silver and copper are the metals most commonly used, and when 
 used in small quantities do not alter very markedly the properties 
 of gold. Copper seems to produce a greater change in properties than 
 silver. The effect of alloying gold with 10 per cent, of copper to produce 
 the standard coin is well known. The effect of alloying gold with silver 
 is less well known, though it appears quite probable that in the future, 
 as restrictions are placed upon the use of large quantities of gold in 
 places where something else will serve quite as well, there will be 
 created a new interest in alloys of gold and silver for many large cast- 
 ings. The difference in the effect of alloying gold with copper and 
 silver is shown in the table of hardness tests. It may be seen that 
 there is a marked difference in hardness between Ney's dark 22 k. 
 gold and 22 k. light gold. The formula of each may be seen in the 
 following list of formulae^ of gold plates in general use : 
 
 22 k. dark gold plate. 22 k. light gold plate. 20 k. gold plate. 
 
 Gold . . . 92.00 Gold . . . .92.00 Gold . . 83.25 
 
 Silver . . 4.50 Silver .... 7.70 Silver . . 12.00 
 
 Copper . . 3.50 Copper .... 0.30 Copper . . 4.75 
 
 It may be noted that almost 8 per cent, of silver has made practically 
 no difference between the hardness of the light 22 k. gold and that of 
 pure gold. The slight difference in hardness shown is probably due to 
 the very small amount of copper contained in this alloy. Silver and 
 copper unite in all proportions and form a valuable series of alloys, 
 having many applications in the arts. Whenever these two metals in 
 the form of an alloy are combined with gold they seem to have a 
 marked influence in hardeniag it, as may be observed by the tests on 
 the 20 k. gold plate, which has considerably higher percentages of both 
 copper and silver than the higher carat golds. The alloys of gold, 
 silver and copper are also sufficiently tough to resist the forces of masti- 
 cation when used in the quantities which are permissible, and are used 
 in large quantities by dentists in the coastruction of crowns, bands, 
 inlays and other restorations. 
 
 Zinc is also used to alloy gold in the prod iction of solders for the 
 operations which require the union of the various parts of restorations. 
 The gold solders are designated as 22 carat, 20 carat, 18 carat, etc., as 
 the case may be, which indicates the carat of the gold upon which they 
 may be melted without loss of form of the gold plate. The following 
 
 ' These and the following analyses shown for the various alloys of gold were made for 
 this chapter by E. O. Scott during the early part of 1920 from alloys obtained from the 
 market. 
 
348 PROPERTIES OF FILLING MATERIALS 
 
 formulse of three of these alloys show that they are not of the carat 
 that they are named, but are intended to be used upon gold of the 
 carat marked upon them. 
 
 Formula of Solders. 
 
 
 22 k. solder. 
 
 20 k. solder. 
 
 18 k. solder. 
 
 Gold . 
 
 . 84.00 parts. 
 
 Gold . . 76.00 parts. 
 
 Gold . . 68.00 parts 
 
 Copper 
 
 7.50 " 
 
 Copper . 11.50 " 
 
 Copper . 14.50 " 
 
 Silver . 
 
 5.50 " 
 
 Silver . . 8.50 " 
 
 Silver . . 12.50 " 
 
 Zinc 
 
 3.00 " 
 
 Zinc . . 4.00 " 
 
 Zinc . . 5.00 " 
 
 Zmc, like copper, lowers the melting-point and hardens the gold. 
 The latter, however, seems to be the principal reason for the use of 
 zinc in solders, for the former could be obtained with copper. Zinc 
 also controls the color to some extent. 
 
 The formulae of the solders given are correct for one manufacturer's 
 product only. There are variations in the quantities of gold used by 
 the different manufacturers. Some of them may reduce the quantity 
 of gold for the purpose of reducing the melting-point, some may want- 
 to vary the color somewhat and some undoubtedly pursue this practice 
 to lessen the cost of production of the solder. The following table 
 shows the advertised fineness of three manufacturers' solders: 
 
 1 
 
 Carat. 
 
 Fineness. 
 
 Carat. 
 
 2 
 
 Fineness. 
 
 Carat. 
 
 3 
 
 Fineness 
 
 22 
 
 750 
 
 22 
 
 802 
 
 22 
 
 830 
 
 20 
 
 729 
 
 20 
 
 735 
 
 20 
 
 708 
 
 18 
 
 6661 
 
 18 
 
 656 
 
 18 
 
 615 
 
 The variations in the amount of gold used are likely to cause varia- 
 tions in the color of the solder and appreciable differences in the melting- 
 points. It is generally safer, therefore, to use the same make of solder 
 as the plate. 
 
 Platinum and palladium are used with copper and silver to alloy 
 gold to produce hard and elastic alloys known as clasp metals. The 
 following formulae represent two well-known clasp metals in the 
 market : 
 
 Gold . . 
 
 64. 00 per cent. 
 
 Gold . . . 
 
 . 63.25 per cent 
 
 Platinum . 
 
 11.00 
 
 Platinum . 
 
 . 10.00 
 
 Palladium 
 
 16.50 
 
 Silver . 
 
 . 19.35 
 
 Silver . 
 
 1.50 
 
 Copper 
 
 7.40 
 
 Copper 
 
 7.00 
 
 
 
 Other alloys containing gold, platinum, palladium, silver and copper 
 have been recently introduced as desirable for casting fillings, crowns, 
 etc. This class of alloys usually contains not less than 80 per cent, of 
 gold, from 6 per cent, to 10 per cent, of platinum, about 2 per cent, of 
 
NATURE OF AMALGAM 349 
 
 palladium, 0.05 per cent, to 2 per cent, of silver and 2 per cent, to 9 
 per cent, of copper. This class of alloys generally has lower melting- 
 points than either platinum or pure gold. They are said to be more 
 fluid when melted and as a result enable the mold to be filled more 
 perfectly than with other alloys. 
 
 NATURE OF AMALGAM. 
 
 An amalgam is a combination of two or more metals, one of which 
 is mercury, and may be either a liquid, solid or semi-solid. The term 
 amalgam is derived from the Greek malagma, from mallasso, to soften, 
 the presence of mercury lowering the melting-point of such a mixture. 
 
 The term metal indicates a certain number of chemical elements 
 which in the present state of chemical science are undecomposable 
 and possess certain well-defined characters in common, such as opacity, 
 luster, conductivity, high specific gravity and plasticity or capability 
 of being drawn, squeezed or hammered without loss of continuity.. 
 
 Comparatively few of the metals possess characters such as render 
 them suitable to be employed alone by manufacturers, although there 
 are many applications for most of them when two or more are caused 
 to unite permanently. The compound thus formed by the union of 
 two or more metals is termed an alloy. The word alloy is believed 
 to have been derived from the French aloi (the metal of the standard 
 coin), a contraction of a la loi (according to law). Aa amalgam, then, 
 represents that class of alloys which contain mercury: the agencies 
 by which the union of metals is efi^ected are heat, electro-deposition, 
 pressure at ordinary temperatures and the dissolving of one or more 
 metals which exist in a solid state at ordinary temperatures in a metal 
 which exists in a liquid state at ordinary temperatures. 
 
 Practically all alloys, except dental amalgam alloys, are formed 
 through the agency of heat, but certain soft metals, such as lead, tin, 
 bismuth, cadmium, etc., have been shown by Professor Spring, of 
 Liege, to form true alloys under pressure and absence of heat. This 
 process, however, has not as yet found application much beyond the 
 laboratories, where it is used to demonstrate that there is actual 
 union between the particles of different metals in the cold when they 
 are brought into intimate contact. Certain alloys, such as gold and 
 copper, or copper and zinc, may be prepared by electro-deposition. 
 Several alloys are prepared by this method on a large scale. 
 
 The utility of dental amalgam alloys depends largely upon the 
 property which mercury has of dissolving most other metals to the 
 point of saturation, forming alloys which, when allowed to stand for 
 some time, harden or set. This hardening or setting process is probably 
 
350 PROPERTIES OF FILLING MATERIALS 
 
 due to the formation of a chemical compound between the mercury 
 and one or more of the metals used in combination with it. The mass 
 thus formed of metal or alloy in combination with mercury cannot be 
 regarded, however, as a true amalgam, for Matthiessen has pointed out 
 that such a mixture may be either a chemical compound, a solidified 
 solution or a mixture of all three. 
 
 There are some phenomena, such as change in volume, change in 
 strength and evolution of heat that lead to the belief that definite 
 compounds do exist in definite proportions by weight. Most of the 
 metals used to form the alloy which is combined with mercury to form 
 an amalgam are capable of existing in a state of chemical combination, 
 although they are subject to Matthiessen's classification, and are 
 usually united by feeble affinities, for it is necessary, in order to produce 
 energetic union, that the constituents exhibit much dissimilarity in 
 properties. There is little doubt that some of these metals do unite 
 in definite proportions, although it is difficult to obtain them as such 
 since the compounds thus formed dissolve in all proportions in the 
 melted metals from which they do not differ very Widel}^ in their 
 melting-points. For these reasons it has been questioned whether not 
 only amalgams, but any alloy were a true chemical compound. 
 
 Definite compounds have been proved to exist, however, in both 
 the native and artificial states. Hiorns^ has given a good illustration of 
 a chemical compound between two metals in the alloy of copper and 
 tin which may be represented by the formula SnCu2, containing 38.4 
 parts of tin and 61.6 parts of copper. A well-known native chemical 
 compound of two metals is represented by silver and mercury, which 
 are found crystallized together in the following proportions: (Ag2Hg2 
 or Ag2Hg6) and (Ag2Hg6) . Many other examples may be given. 
 
 Under the term solution of one metal in another we understand one 
 like ether and alcohol, or any two substances which may be mixed in 
 all proportions and will not separate into layers by standing. Solidified 
 solution would indicate the solidification of a perfectly homogeneous 
 diffusion of one body in another and has been represented by glass, 
 which is formed in the liquid state at a high temperature and solidified 
 on cooling without separation of the different silicates. Hiorns quotes 
 Mendeleef as saying that solutions are fluid, unstable, definite chemical 
 compounds in a state of dissociation, and that of such a kind are most 
 metallic alloys. They have been considered in the Journal of the 
 Chemical Society as solidified solutions of metals which contain definite 
 compounds in excess of one of the constituent metals. The subject of 
 solution apparently has a most important application in the production 
 pf dental amalgams. 
 
 1 Mixed Metals qr M^tallig Alloys, 
 
NATURE OF AMALGAM 351 
 
 In the same manner that water dissolves saHne substances, alcohol 
 dissolves resins, ether dissolves fats, etc., mercury dissolves most 
 metals. A very interesting phenomenon to observe in this connection 
 is the manner in which most solvents act upon solids (Hiorns.) As a 
 rule the dissolving power of each liquid is confined to a certain class of 
 solids. It is also a general rule that the solubility of a body in any 
 medium depends upon a similarity in the constitution of the body and 
 the solvent. 
 
 When a liquid has dissolved all of a solid that it is capable of retaining 
 at a given temperature it is said to have become saturated; but even 
 if it be saturated with one solid it may yet take up another, and often- 
 times that solvent power is thereby increased. 
 
 A general survey of the literature reveals quite a lack of knowledge 
 of the peculiarity of solidified solutions and appears to explain to some 
 extent why there has been so much misunderstanding connected with 
 the use of amalgam. While it appears important that the subjects of 
 solutions, crystallization and diffusion should be considered in con- 
 nection with the formation of dental amalgams, it does not seem pos- 
 sible to make anything but general statements from the data available. 
 
 It seems to be generally accepted that when one or more metals 
 combine with mercury to form a dental amalgam, when the mass sub- 
 sequently sets and the final complete diffusion takes place the same 
 agencies control ordinary chemical phenomena. External heat, for 
 example, influences these phenomena^ to a marked degree in some 
 instances, it being considered that a rise in temperature of 10° C. will 
 double the velocity of most chemical reactions. The conversion of 
 chemical energy into heat may also influence these phenomena. The 
 condition of contact between the mercury and metal or alloy will 
 likewise have its influence upon these phenomena.^ Internal move- 
 ments of the component parts of the mass may facilitate diffusion, 
 solution and chemical reactions. Vibration, in some cases, will do the 
 same. In fact, about the only difference that appears between dental 
 amalgams and most chemical reactions in regard to controlling factors 
 is that the metals are united by feeble affinities, and there exists a 
 tendency for the amalgam to possess the properties of the constituents. 
 There are some cases where a combination is totally difterent from 
 either constituent but the general effect is for each constituent metal 
 to maintain its identity. Oftentimes two metals with like physical 
 properties may be combined to produce a whole series of alloys which 
 have the same properties as the constituent metals. On the other 
 
 1 Arthur W. Gray, Director of the Caulk Physical Research Laboratory, Journal 
 National Dental Assn., 1919, and Transactioua q( th.^ Affierican Institute of Mining 
 Engineers, 1918, 
 
 « Xbid. 
 
352 PROPERTIES OF FILLING MATERIALS 
 
 hand, if two metals with dissimilar physical properties be combined, 
 the result may be a product quite different from either constituent 
 depending upon the nature and arrangement of the eutectic. 
 
 The advantage in alloying metals, therefore, seems to be to assemble 
 in one compound a number of properties which cannot be found in one 
 metal. 
 
 Through the work of Flagg and Black, silver, tin, copper, zinc, and 
 occasionally gold in small quantities have been found to possess more 
 desirable and less undesirable properties than any other equal number 
 of metals. Since the work of Dr. Black^ two new but distinct classes 
 of alloys have appeared as the principal products of nearly all leading 
 manufacturers. One of them contains from 65 to 68 per cent, of 
 silver, 26 to 28 per cent, of tin, 3 to 5 per cent, of copper, and | to 2 
 per cent, of zinc. The other contains from 43 to 48 per cent, of silver, 
 48 to 58 per cent, of tin, and 1 to 2 per cent, of zinc. The first class 
 is known as high percentage silver alloys, quick setting alloys, and 
 Black's alloys, the three names being synonymous. The second class 
 is known as low percentage silver alloys, slow setting alloys, and plastic 
 alloys. Both classes seem to have grown out of Black's work, the 
 latter class undoubtedly to the detriment of dentistry. 
 
 The first class seems to be based upon the properties of 72| per cent, 
 of silver and 27| per cent, of tin, the most important of which is the 
 small amount of shrinkage which takes place when this alloy is con- 
 verted into amalgam. The second class seems to be based upon the 
 dual movement of 50 per cent, of silver and 50 per cent, of tin, which, 
 by referring to Dr. Black's^ charts is seen to be about 2 points. Besides 
 the two principal classes of alloys mentioned, there are in the market 
 many of the alloys made and used previous to Dr. Black's work in 
 1895-1896. 
 
 Townsend's original alloy of silver 42 per cent, and tin 58 per cent. 
 is still used by some. 
 
 Flagg' s alloys, especially the one containing silver 60 per cent., tin 
 35 per cent, and copper 5 per cent., are still in the market and used by 
 some. 
 
 There are a dozen or more alloys made to supply the varied demands 
 of the profession. Some of them have one or more prominent qualities, 
 but, as a rule, they are not free from a reduction in volume at the 
 time of and subsequent to insertion, nor do they seem to be based upon 
 any particular principle, as are the two classes which have resulted 
 from Black's work. Inasmuch as these alloys are also composed of 
 silver, tin, copper and zinc, they are subject to the same consideration 
 
 1 Dental Cosmos, 1895-1896. 2 jbid. 
 
NATURE OF AMALGAM 353 
 
 as far as physical and chemical properties are concerned. It would 
 seem that dental amalgams are best understood by dividing them into 
 the two classes spoken of as high percentage silver alloys and low per- 
 centage silver alloys. The difference between the two can probably 
 be best represented by first considering the most important properties 
 of each constituent. 
 
 Silver unites with mercury in definite proportions, and through its 
 comparatively strong aflfinity for mercury and its large proportions it 
 largely controls the setting. It tarnishes quite readily in sulphuretted 
 hydrogen and soluble sulphids. It increases in volume when amal- 
 gamated. It increases edge strength, lessens the fiow and because of 
 its great tendency to crystallize and its property of going into solu- 
 tion in mercury slowly at ordinary temperatures it causes the alloy to 
 amalgamate tardily and the mass to work hard. 
 
 Tin unites with mercury in all proportions at all temperatures, 
 forming a weak crystalline compound. It retards the setting, decreases 
 in volume when amalgamated, decreases edge strength, increases the 
 flow, and imparts plasticity, thus causing the mass to work easily. 
 
 Copper unites with mercury with difficulty at ordinary temperatures, 
 although in definite proportions it generally hastens the setting, 
 increases edge strength, lessens flow, does not change appreciably in 
 volume when amalgamated and is easily tarnished by sulphuretted 
 hydrogen and soluble sulphids. 
 
 Zinc unites with mercury easily and in definite proportions, increases 
 in volume when amalgamated, hastens the setting, increases edge 
 strength, lessens flow, improves color and imparts a peculiar smooth- 
 ness to the mass during amalgamation. 
 
 Gold when melted with the other constituents, as most of the 
 present alloys are made, adds almost no desirable properties and adds 
 one or two undesirable properties. It adds a little to the color and 
 makes a very tough amalgam, but imparts a peculiar pasty springi- 
 ness which makes it difficult to pack. There are some possibilities in 
 the use of gold in small quantities, however, that are not fully developed 
 and which may lead to a more general use of this metal. 
 
 From the nature of metallic alloys we may assume that certain 
 proportions of these constituents enter into combination and other 
 portions are simply in a state of mixture or solution. From the similar- 
 ity of the metals we may assume that energetic union has not taken 
 place, and, as a result, the portions united chemically are not expected 
 to have properties diverging widely from their constituents. 
 
 Since solutions and mixtures generally possess the properties of 
 their constituents, we would expect a compound of these metals to be 
 quite largely the sum of the properties of its constituents. Such seems 
 23 
 
354 
 
 PROPERTIES OF FILLING MATERIALS 
 
 to be the case with these alloys. A point to be observed in the con- 
 sideration of these alloys is that one or two metals are used as the base 
 of the alloy and the others as modifiers, the attempt being made to 
 add to the properties of the basal constituents some of the properties 
 of other constituents. 
 
 A consideration of the alloys now in use, with one or two exceptions 
 shows that the selection of these metals and the proportions of each 
 have been made with reference to their physical behavior, special 
 emphasis being placed upon changes in volume, color and strength. 
 Fenchel,^ however, has studied amalgams from a different point of view. 
 He has taken a break in the cooling curve of any liquid (including 
 melted metals) to indicate a change in physical constitution, and from 
 this traced the crystallizing curve of some of these alloys in increasing 
 proportions to each other. He has studied the structure of these 
 alloys microscopically as well as with reference to alteration in form, 
 resistance to stress, specific gravity and electromotive force of currents 
 set up in the mouth by different metals, all of which form a very valu- 
 able part of scientific literature. Fenchel's work may be said to follow, 
 more closely the chemical phases of alloys than the physical ones, 
 while the work of others seems to be devoted largely to the physical 
 properties. 
 
 A B c D E F 
 
 Fig. 339. — Test cylinders of amalgam prepared by amalgamating 6 gm. alloy. Cylin- 
 ders A and B from low-silver alloy compress and crack. Cylinders C, D, E, and F from 
 high-silver alloy burst explosively. Cylinders B and D, both packed under 400 kg. show 
 difference in size of amalgam from same weight of alloy. D is 25 per cent, larger and 
 75 per cent, stronger than B. C, D, and E are packed under 141, 400, and 1131 kg. 
 per cir. cm. respectively. Natural size 10 mm. in diameter. 
 
 It would appear that a clear understanding of the physical behavior 
 of these alloys cannot be had without at least a working knowledge 
 of their chemical behavior. For the present, however, our knowledge 
 of alloys (the two classes mentioned) is confined largely to their 
 physical behavior. The principal difference between the two classes 
 of alloys should be obvious. The first, with more silver, less tin and 
 some copper is stronger, more stable in form, more free from decrease 
 in volume, though it works hard and sets quickly. The second, with 
 
 1 Fgr a gtudv of Fenchel's work see his various papers in the D^n^al CpsmQs, 
 
NATURE OF AMALGAM 
 
 355 
 
 3000 
 
 y 4000 
 O h 
 
 K 2 
 
 np 
 i_ z 
 
 V? uJ 
 ^ O 
 
 tB < 
 
 5^ 
 
 >:: £ 
 
 O c 2000 
 
 2 y 
 X Q. 
 ^o 
 
 Z 1000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 /^ 
 
 
 
 
 -• ■ 
 
 
 
 
 
 • 
 
 
 
 - 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ?5— 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 HIGH 
 SILVER 
 
 LOW 
 SILVER 
 
 10 20 
 
 AGE OF AMALGAM IN DAYS 
 
 30 
 
 40 
 
 4000 
 
 UJ 
 
 in 2 
 
 L. U 
 
 < :;! 3000 
 
 Z 3 
 
 lU U 
 
 !o o 
 
 ,3 c 2000 
 
 z u 
 X Q- 
 
 §3 
 
 z 1000 
 
 • 
 
 yf-H ^ 
 
 i __^ "i I* T 
 
 HIGH 
 SILVER 
 
 LOW 
 SILVER 
 
 2 4 
 
 AGE OF AMALGAM IN HOURS 
 
 Fig. 340.- 
 
 -Hardening of amalgams. Amalgam from high-silver alloy is 75 per cent, 
 stronger than that from low-silver fjUoy. 
 
356 PROPERTIES OF FILLING MATERIALS 
 
 its high percentage of tin, low percentage of silver and absence of 
 copper is easier to amalgamate, sets slower, is weaker and is a little 
 lighter in color (Figs. 339 and 340). ^^ 
 
 These two classes of alloys resemble some of the older as well as 
 many of the newer ones by having some properties in common. 
 
 Contraction and expansion, for example, seem to be phenomena 
 accompanying the setting of all dental amalgams. Pioneer workers 
 seem to have attributed these properties to the composition of the 
 alloy. Later work showed that annealing the cut alloy had a marked 
 influence upon change in volume. The most recent work has furnished 
 additional evidence to substantiate the claims of the author in a 
 former edition of this book that other things than composition and 
 annealing of the cut alloy had their influence upon the phenomena 
 accompanying the setting of dental amalgams. 
 
 The thoroughness with which this recent work has been done seems 
 to have proved, beyond doubt, that many of the same factors which 
 control the behavior of other alloys control dental amalgams. Promi- 
 nent among such factors are: packing pressure, packing time, tri- 
 turation time, mercury alloy ratio, size of the alloy particles, tem- 
 perature at which the dental amalgam is kept and age of the amalgam. 
 On account of the acknowledged inferiority of the low percentage 
 silver alloys little or no data will be presented to show their behavior, 
 it being assumed that a modern high-grade practice cannot be con- 
 ducted by the use of these materials. What follows, therefore, has 
 special reference to the high percentage silver alloys (Figs. 341 and 
 342) .3 4 
 
 It may be seen that the curves (Fig. 342 and curve 180, Fig. 341) 
 agree in a general way with respect to the changes in volume that 
 take place at the time and subsequent to the combination of the 
 mercury and alloy in a high percentage silver amalgam. There appears 
 to be a contraction at the time and immediately after the combination 
 of mercury and alloy has taken place, which is followed by a slow 
 expansion. This is followed by a still slower contraction which, if the 
 alloy be properly made, brings the volume of the amalgam to approxi- 
 mately the point of beginning. Earlier workers have failed to note the 
 first movement of dental amalgams on account of the use of instru- 
 ments not suitable for this work, and have, in many instances, failed 
 to detect the final slow contraction. 
 
 This manner of manipulation to produce this typical reaction curve 
 is described under the chapter on Manipulation of Amalgams, with 
 the possible exception of the pressure used in packing. In Fig. 341, 
 curve No. 180 was packed with 100 kg. per circular centimeter. No. 
 
 1 Arthur W. Gray. 2 jbid. s Ibid. 
 
 ^ Souder and Peters: Dental Cosmos, March, 1920. 
 
NATURE OF AMALGAM 
 
 357 
 
 178 with 400 kg. per circular centimeter and No. 181 with 1600 kg. 
 per circular centimeter. It remains to be proved that the pressure 
 used in the production of the typical reaction curves is not more than 
 
 0.05 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 <^ 
 
 ><-^ 
 
 
 RI80 
 
 
 . 
 
 
 
 
 
 — 
 
 
 ^ 
 
 "^^ 
 
 ^---- 
 
 R178 
 
 j^^^^ 
 
 J 
 
 
 
 0,05 
 
 
 
 
 RI8I 
 
 
 
 
 
 
 
 
 
 
 
 
 
 2 4 6 8 
 
 AGE OF AMALGAM IN HOURS 
 
 Fig. 341. — Typical reaction expansion curve (R180) and modifications caused by 
 increase of packing pressure. 
 
 is used in practice if the movements represented by these curves are 
 to be taken as indicative of what takes place in practice. There seems 
 to be no doubt but that they are quite accurate and furnish a valuable 
 lesson for those who have been inclined to ignore the packing pressure 
 as a factor in modifying the behavior of dental amalgams. It may 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 V 
 
 ^ 
 
 ^-f~- 
 
 ^ 
 
 ^ 
 
 
 
 
 
 
 
 /?-/ 
 
 il-e 
 
 t.sc 
 
 /i 
 
 f 
 
 ,v*^ 
 
 
 :::::- 
 
 ^_ 
 
 _^ 
 
 
 — 
 
 
 
 
 S■^ 
 
 Zl'l 
 
 t t< 
 
 
 / 
 
 / 
 
 
 
 
 
 
 — - 
 
 
 
 '"' 
 
 A. 
 
 — i^ 
 
 fiSA. 
 
 f 
 
 / 
 
 
 
 
 
 
 
 
 
 
 
 6-4 
 
 H-c 
 
 tl.CC 
 
 V 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ^ s J 4 s e 7 e 5 w // la ij /-f /s 
 Fig. 342. — Setting changes in amalgam maintained at nearly the same temperature. 
 
 be noted that in curve No. 178, where the packing pressure was raised 
 from 100 kg. to 400 kg. there is no initial contraction shown, for the 
 reason that the increase in the pressure has hastened the reaction to 
 
358 
 
 PROPERTIES OF FILLING MATERIALS 
 
 such an extent that this movement has taken place before it could be 
 detected or possibly during the mixing of the alloy and mercury. 
 Curve No. 181 shows the slow expansion that we formerly thought 
 took place in an hour or two to have taken place during the first few 
 minutes, due to a further increase in the packing pressure from 400 kg. 
 
 0.20 
 
 0.15 
 
 0.10 
 
 0.05 
 
 0.05 
 
 0.10 
 
 
 
 
 
 
 
 
 R58 
 
 
 
 
 
 
 > 
 
 
 
 
 
 
 
 ^ 
 
 ^ 
 
 
 
 
 
 
 y 
 
 
 
 
 
 
 > 
 
 ^ 
 
 
 
 
 
 
 
 ^ 
 
 
 
 
 
 
 
 // 
 
 ""^ 
 
 \ 
 
 
 
 
 
 
 
 
 
 "^^ 
 
 
 
 
 
 
 
 
 R59 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 V 
 
 
 
 
 
 
 
 
 \ 
 
 
 
 
 
 
 
 
 \ 
 
 ^ 
 
 
 
 
 
 
 R66 
 
 
 
 
 - 
 
 
 
 
 
 
 
 
 age: of amalgam in hours 
 
 Fig. 343. — Effects of changing size of^alloy particles. 
 
 to 1600 kg. and consequently a further hastening of the setting. While 
 it is true there is less mercury retained in a mass of amalgam (Fig. 343) 
 as the pressure is raised, these and other data that are available appear 
 to show that increases in pressure hasten the reaction between alloy 
 and mercury and, as a result, change the reaction curve of volume 
 change. This should be expected, for it is well known that as com- 
 bining substances are brought into more intimate contact the more 
 rapid will be the reaction. 
 
 It has recently been demonstrated that continuing the pressure 
 longer than usual will produce somewhat the same result as increasing 
 the pressure, though undoubtedly to a less extent. Increasing the 
 trituration time (see Mixing Alloys) of alloy and mercury also has to 
 
MATURE OF AMALGAM 350 
 
 do with condition of contact and has been demonstrated to accelerate 
 the reaction of the alloy and mercury up to a certain point where 
 setting begins. This will likewise change the reaction curve. In a 
 similar manner the rate of reaction may be modified by varying the 
 percentages of mercury and alloy for this, too, may modify the con- 
 dition of contact. 
 
 Still further data on modification of the reaction curve by varying 
 the condition of contact between the reacting substances are con- 
 tained in Fig. 343,^ which shows the results of amalgamating three 
 different sizes of alloy particles. 
 
 Curve R58 represents the reaction that took place from the use of 
 alloy particles that were too coarse to pass through a sieve of 48 meshes 
 to the inch. Curve R59 shows the reaction when alloy particles that 
 would pass through a sieve 200 meshes to the inch were used and R66 
 when still finer particles were used. By comparing these curves with 
 the typical reaction curves (Figs. 341 and 342) it may be seen that as 
 the alloy particles were made progressively finer the reaction was 
 accelerated and characteristic features appeared earlier and more 
 prominently. 
 
 It is well knowTQ that as heat is increased, molecular activity is also 
 increased, resulting in accelerated chemical reactions and increased 
 solubility of some substances for others. Not until recently, 
 however, has this been recognized as having its influence upon the 
 reaction between mercury and alloys with which to produce dental 
 amalgams. It does not appear that the temperature of amalgam 
 fillings inserted by the dentist can be detected and controlled, hence 
 this factor in volume change is not of special interest to him. Those 
 who are doing experimental work, such as comparing different products 
 with delicate instruments for detecting changes in volume, may observe 
 marked differences in the reactions that will take place at freezing 
 temperatures and temperature of the body. 
 
 It has not been customary for those familiar with the behavior of 
 dental amalgams to mention the age of the amalgam when descriptions 
 of changes in volume were given. Notwithstanding this custom it 
 has been known for many years that amalgams changed in volume 
 and that this change in volume did not all take place suddenly. By 
 referring to Fig. 341 , it may be seen that Gray shows changes in volume 
 at the end of seven hours and Souder and Peters (Fig. 342) show 
 changes at the end of twenty-five hours. The author has repeatedly 
 found these changes to continue over a period of several months when 
 the amalgam was packed with hand-pressure and the mass has been 
 incompletely mixed, as is often done in practice. If, therefore, the 
 
 1 Gray, Arthur W. 
 
360 PROPERTIES OF FILLING MATERIALS 
 
 amount of volume change that accompanies the setting of these amal- 
 gams is to be given, the age should also be given, for it is of little value 
 to know that an amalgam expands or contracts a certain number of 
 points unless it is known whether the figures represent the total volume 
 change or only a portion of it. 
 
 From the foregoing it seems established that there are several ways 
 that one who makes a dental amalgam filling may vary its volume 
 change. The two factors of most importance, however, are compo- 
 sition and the annealing of the cut alloy, both of which are under the 
 control of the manufacturer of these products, the former entirely and 
 the latter to a marked degree. / 
 
 With Flagg's work as a basis, Black seems to have established suffi- 
 ciently accurately for practical purposes the contraction and expansion 
 ranges for the metals that appear most suitable for the production of 
 alloys for making dental amalgams. He assumed that of the properties 
 which amalgams possess, nothing was of as much importance as free- 
 dom from contraction. He regarded it as imperative that there must 
 be absolute freedom from contraction and only a minimum of expan-- 
 sion. With this view of the situation he constructed more accurate 
 instruments than had been used previously and made numerous 
 experiments to determine not only the metals but the proportions 
 which would yield such an amalgam as the one referred to. 
 
 He concluded that an amalgam could be made that would lie abso- 
 lutely still while hardening. Later workers,^ - ^ with more delicate 
 instruments than those used by Black, seem to have demonstrated 
 (Figs. 341 and 342) that none of the amalgams now in use are entirely 
 free from change in volume. 
 
 In describing his experiments. Black"* stated that a fixed formula 
 was not good for general use on account of inability to get metals 
 which are chemically pm-e at a price that was permissible for the 
 production of these alloys for amalgams. He and those who followed 
 his teachings clakaed that a general formula might be adopted for a 
 given batch of metals, and then it was necessary to experiment with 
 this batch of metals by varying this general formula in order to get a 
 product that would lie still. 
 
 Some reputable manufacturers declined to accept this view and 
 claimed their products were made from fixed formulae. Inasmuch as 
 the claims of the adherents to a fixed formula have not been disproved 
 and their products appear to show the same behavior as the products 
 that are said to be made from a plan instead of a fixed formula, it 
 appears more reasonable to believe that fixed formulse will yield given 
 results provided the technic in production is properly controlled. Since 
 
 1 Souder and Peters. ^ Gray, Arthur W. 
 
 3 Ward, Marcus L. : Dental Cosmos. * Operative Dentistry, vol. ii. 
 
NATURE OF AMALGAM 361 
 
 nothing has been written by Dr. Black or his followers about the 
 manner of preparing these products nor the character of the impurities 
 that silver, tin, copper and zinc are said to contain, it appears likely 
 that inability to produce fixed products from fixed formulae was due 
 to inability to maintain fixed conditions in the process of production, 
 A review of Fenchel's work and the earlier work of Kirk and Burchard, 
 each of whom has viewed more closely the chemical phases of alloys, 
 would not suggest the plan offered by Black. 
 
 The question, " Why does a fixed formula not give an alloy with a 
 definite volume change," has been asked of the author so many times 
 by teachers and practitioners alike, that it would seem that the plan 
 suggested by Black has not been understood nor accepted by the 
 profession. All seem agreed, however, that the plan gives as good 
 results, and furnishes the profession with as good alloys, as our present 
 knowledge of the subject will permit. It is in the manner of reaching 
 the result that there seems to be a difference of opinion. The plan 
 implies more than the mere assumption that impure metals will not 
 give a definite change in volume. It implies that metals cannot be 
 constantly obtained with a degree of impurity, for if a metal contained 
 a certain impurity in certain quantities every time it was purchased, 
 allowance could be made for it in the formula. 
 
 While, as a rule, native metals are not to be relied upon, there are 
 some instances in which impurity can be determined and allowance 
 made for it comparatively easily. It is quite sweeping in its scope, 
 however, to say that refined metals cannot be obtained which are 
 quite constant in their impurities. 
 
 The author made analyses of three high percentage silver alloys 
 within the last year, which were, in his opinion, most widely used and 
 most accurately made, with a view of further confirming his opinion 
 that more than one formula will give practically the same volume of 
 change provided the formula selected lies within the ranges given for a 
 high percentage silver alloy. They are as follows: 
 
 No. 1 
 
 Silver 68 . 00 per cent. 
 
 Tin 26.00 
 
 Copper 5.00 " 
 
 Zinc . 1.00 " 
 
 No. 2 
 
 Silver 67.00 
 
 Tin 27.00 
 
 Copper 5.00 
 
 Zinc 1.00 
 
 No. 3 
 
 Silver :. 67.00 
 
 Tin 27.00 
 
 Copper 5.00 " 
 
 Zinc 1.00 
 
362 PROPERTIES OP PJLLlKG MATERIALS 
 
 By comparing these analyses with the many pubhshed formulae 
 contained in dental literature it may be seen there is a much nearer 
 uniformity in composition than existed about ten years ago. Repeated 
 analyses of the first alloy, however, have shown a constant tendency 
 to contain more silver than most alloys in the market, though the 
 volume change seems to be the same under the same conditions of 
 manipulation. 
 
 There appears to be one thing of special interest in the three analyses 
 given, namely, the uniform use of zinc in small quantities. Within 
 recent years a very few manufacturers have eliminated the zinc entirely, 
 apparently on the basis of some of the last words from Dr. Black on 
 the subject of amalgam, which seem not to have been substantiated 
 by experimental work. Dr. Black stated that 0.05 per cent, of zinc 
 was not desirable, for the reason that amalgams containing it would 
 continue to change in volume for five years or more. Determinations 
 for zinc in alloys for amalgams have been made by the author on 
 several of the best products now in use, with affirmative results in 
 most cases showing that the judgement of a large majority of the manu- 
 facturers is in favor of the use of zinc in small quantities, in order that 
 their products will be more free from contraction and more permanently 
 light in color. The few who manufacture so-called high percentage 
 silver alloys without any zinc are not known to possess modern instru- 
 ments for detecting changes in volume, nor are they among those 
 who have published anything with respect to the effect of using zinc 
 in alloys except that Dr. Black advised against its use in his latter days. 
 
 Since Dr. Black is supposed to have approved of the use of zinc in 
 his earlier days of experimentation, and practically all of the best 
 products in the market (the high percentage silver alloys) have been 
 based upon its use, the placing in the market of the same alloys without 
 the zinc has caused some controversy. Both participants to the contro- 
 versy claim to have products made according to Black's plans. Those 
 who use no zinc claim to have a product that is more free from expan- 
 sion, while those using the zinc claim to have products more free 
 from contraction. The author has studied this problem for some time 
 and has had hearty cooperation on the part of some of the most able 
 manufacturers as well as advice from the Bureau of Standards on 
 instruments for detecting changes in volume. As these studies have 
 proceeded it has become more evident that if an alloy for a dental 
 amalgam is to have a minimum of contraction it must contain from 
 I per cent, upward, not exceeding 2 per cent, of zinc. Reference to the 
 analyses given shows the judgment of three large, reliable, and, in the 
 opinion of the author, most capable manufacturers, which is that about 
 1 per cent, of zinc should be used. 
 
NATURE OF AMALGAM 303 
 
 The other known factor in changes in vohnne, annealing the cut alloy, 
 is of special interest for the reason that to a small degree it is con- 
 trolled by the dentist, though it must be kept in mind that this variable 
 is controlled largely by the manufacturer. 
 
 Annealing of Alloys. — Dr. J. Foster Flagg seems to have been the 
 first to call attention to the fact that alloys which were freshly cut 
 behaved differently when amalgamated than the same alloys did after 
 they had stood for some time. Dr. Black traced the phenomenon 
 through a great number of experiments and finally arrived at the 
 conclusion that the cut alloy is hardened by the violence in cutting, 
 the condition thus produced being analogous to the condition of the 
 same metals in hammering. His earlier observations led to the belief 
 that motion brought about the change, but later experiments showed 
 that it had no influence. Oxidation was thought to be a factor, but 
 was finally eliminated as one of the causes. After a great many 
 experiments it was proved that the change was produced by annealing 
 or tempering, that is, a molecular alteration of the cut alloy. The tem- 
 perature at which this is produced ranges from room temperature 
 upward. If the alloy be subjected to room temperature for a year or 
 more the same effect is produced as when it is subjected to a higher 
 temperature for a shorter time. It has been found that the low tem- 
 perature and longer time of exposure bring about a more complete 
 annealing. The change can be brought about by subjecting the cut 
 alloy to the temperature of boiling water for about twenty minutes, 
 although there is not quite the same quality to the alloy that there is 
 when it is subjected to a temperature of 120° F. for from two days to 
 a week. The amount of heat required to bring about the change is not 
 the same for all alloys, although each formula seems to change in many 
 of its properties with this treatment. That the property of these alloys 
 to change by so-called ageing or annealing is a physical phenomenon, 
 has been the opinion of Dr. Black and of Fenchel,^ but whether it is 
 caused by hardening during the cutting ptocess, as suggested by Dr. 
 Black, is a question worthy of consideration by those interested in the 
 cause of this peculiarity. 
 
 It is well known that the working of metals forces their molecules 
 into unnatural positions, and that by annealing they are largely restored 
 to their normal state. But it is also well known that the rate and 
 manner of cooling of many metals may preserve in some cases and 
 alter in others the mode of existence of the molecules at the time they 
 were molten. It is also worthy of note in this connection that unequal 
 stresses are set up in some castings by cooling the outer layers of the 
 
 1 Dental Cosmos. 
 
364 PROPERTIES OF FILLING MATERIALS 
 
 metal much more quickly than the interior, thereby causing a com- 
 pression of the interior by the outer layers. 
 
 By annealing, which is the reverse of hardening, the metal flows, 
 and this tension is relieved. The effect of annealing upon changes in 
 volume appears to reduce the amount of expansion of alloys which 
 expand and to increase the contraction of those which contract. Its 
 effect upon the strength of amalgam seems to be to increase the strength 
 of those which set very quickly up to a certain point, after which it 
 seems to decrease the strength somewhat. It does not appear to have 
 the same effect upon the strength of amalgams made from low per- 
 centages of silver. Whether or not these alloys are not hardened as 
 much in their production cannot be said definitely. It seems, however, 
 that practically all alloys for amalgams are hardened to some extent 
 in their production in one way or another and the annealing restores 
 them to what appears to be their natural condition. The makers of 
 high percentage silver alloys for amalgams recognize that these pro- 
 ducts are in a different physical condition after annealing, and as a 
 result of the change produced by the annealing arrange the formulae 
 for these products so that the properties desired are obtained after the 
 annealing has taken place. This procedure is necessary for the reason 
 that annealing of these alloys takes place at room temperature and 
 upward. If, therefore, the change that takes place in the annealing had 
 not been provided for by the maker, and if the annealing had not been 
 given to the alloy by the maker, the practicing dentist would very 
 often have an alloy for amalgam that would vary in the results it 
 would give. 
 
 Another interesting phenomenon brought out by annealing is reduc- 
 tion in the percentage of mercury required to make a plastic mass of 
 alloy and mercury. When the high percentage silver alloys are freshly 
 cut they set so quickly that it is almost impossible to add enough 
 mercury to keep the mass plastic for longer than a very few seconds. 
 As annealing takes place the mass sets more slowly and less mercury 
 is required to make the mass of alloy and mercury plastic. As much as 
 70 per cent, of the mass of alloy and mercury must be mercury before 
 annealing takes place if the alloy used be a high percentage one, while 
 after the same alloy has been fully annealed 50 per cent, will be 
 sufficient. 
 
 This makes four ways that annealing is known to have an effect 
 upon the final result: (1) upon change in volume; (2) upon strength; 
 (3) upon the rate of setting; (4) upon the percentage of mercury to 
 make a plastic mass. 
 
 Some of the makers of these products take advantage of the annealing 
 to control the rate of setting and place upon the market alloys for 
 
NATURE OF AMALGAM 365 
 
 amalgams which are marked rapid setting, medium setting, and slow 
 setting. Present knowledge of the subject leads to the conclusion that 
 this practice is not likely to produce the best result for the reason that 
 annealing also controls, to some extent, volume change. It appears 
 more likely that this practice is followed in order to produce, without 
 adopting the other alternative of altering the formula, alloys with 
 different rates of setting for those who want the mass of alloy and 
 mercury to set quickly enough to enable it to be polished to some 
 extent at the time of setting. 
 
 Thermal Expansion. — Until very recently no data were available 
 to show the relation of amalgam to other materials in common use in 
 dentistry with respect to the expansion that takes place when a sub- 
 stance is heated, and the contraction when cold is applied. The 
 following chart^ has been prepared recently to show how some of the 
 more common materials behave in this respect: 
 
 TABLE I. — ^AVERAGE EXPANSION COEFFICIENTS. RANGE 20° TO 50° C. 
 
 Expansion. 
 Material. Coeff. x lO^ 
 
 Tooth (root) 8.3 
 
 Tooth (across crown) 11.4 
 
 Tooth (root and crown) 6.4 
 
 " 8.7 
 
 " " 8.3 
 
 Synthetic porcelain 7.1 
 
 " " 8.1 
 
 " " 7.5 
 
 Amalgam H ■ . . 26.4 
 
 C 25.0 
 
 K 22.1 
 
 P 24.5 
 
 A 25.4 
 
 B 28.0 
 
 L 24.8 
 
 C ....... 25.0 
 
 C 24.7 
 
 C 28.0 
 
 Porcelain (Bayeux) 4.1 
 
 Gold 14.4 
 
 Platinum . .' . 9.0 
 
 Silver 19.2 
 
 Mercury (linear) 60.6 
 
 Zinc 29.2 
 
 Tin 22.3 
 
 Copper 16.8 
 
 Gutta-percha 198.3 
 
 Aluminum 23.1 
 
 Steel 11.0 
 
 Note. — The above expansions are tabulated as amount of expansion, in microns, for 
 a specimen 1 mm. in length, when heated 1° C., e. g., amalgam C wUl change 25 microns 
 per meter per degree; or, in terms of a specimen 1 cm. long (the approximate diameter 
 of a molar) the expansion is 0.25 micron per degree = 2.5 micron per 10 degree range = 
 12.5 microns per 50 degree range, etc. 
 
 1 Souder and Peters, 
 
366 
 
 PROPERTIES OF FILLING MATERIALS 
 
 Strength of Amalgams. — Strength of alloys indicates those proper- 
 ties by which alloys sustain the application of force or strain without 
 yielding or breaking, and may be considered under two heads, namely, 
 crushing resistance and flow. Crushing resistance is that property 
 by vu-tue of which alloys resist force without fracturing, while flow 
 is that property by virtue of which they resist force without change 
 in shape. 
 
 2 4000 
 
 O 
 
 < 
 
 J 
 
 D 
 
 o 
 
 § 3000 
 
 u 
 a. 
 
 ^ 2000 
 
 z 
 
 1000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 • 
 
 
 
 
 
 
 
 
 X 
 
 
 
 
 
 
 • 1 
 • 
 
 • • 
 
 
 
 
 
 ' 
 
 / 
 
 A 
 
 
 
 
 
 
 
 
 / 
 
 ''. 
 
 
 
 
 
 
 
 
 X 
 
 / 
 
 
 
 
 
 
 
 
 
 / 
 
 
 
 
 
 
 
 
 
 / 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 0.5 
 
 MERCURY-ALLOY RATIO 
 
 1.5 20 
 
 PACKED UNDER 141 KILOS 
 
 Fig. 344. 
 
 — Effects of varying relative amounts of mercury and alloy that are mixed 
 together in making an amalgam. 
 
 Crushing resistance of dental amalgams may be treated (1) as a 
 property of the alloys used to form amalgams, and (2) as a property 
 of the amalgam mass. The crushing resistance of the alloys from which 
 dental amalgams are made seems to be controlled primarily by the 
 composition of the alloy, and secondarily by the annealing and possibly 
 by the process of alloying and chilling. It should be obvious that as 
 the percentages of silver and copper are increased, strength will be 
 increased, other things being the same. Tin being a very soft metal, 
 will decrease the strength as the percentage is increased, other things 
 being equal. Tlie effect of zinc on strength seems to lie between tin 
 and silver and copper. The crushing resistance of amalgam prepared 
 from tjiese allovs presents not oxA^ the same phenomena as tjie alloys^ 
 

 
 
 
 1 
 
 
 
 
 
 
 1 
 
 4000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 '.< 
 
 »^^^ 
 
 < 
 
 
 • • 
 
 • • 
 
 
 
 
 • 
 • 
 
 t 
 
 
 3000 
 
 
 
 / 
 
 / 
 
 
 
 
 
 
 
 
 
 f 
 
 
 
 
 
 
 
 
 2000 
 
 
 I 
 
 f 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ' 
 
 
 0.5 1.0 
 
 WERCURY-ALLOY RATIO 
 
 1.5 2.0 
 
 PACKED UNDER 400 KILOS 
 
 Fig. 34.5.— Modification of Fig. 344, produced by increasing packing pressure from 
 141 to 400 kg. per cir. cm. 
 
 H 
 Z 
 kJ 
 O 4000 
 
 a. 
 
 o 
 
 e 
 u 
 
 ^ 3000 
 
 3 
 
 Z 2000 
 
 (9 
 
 Z 
 
 u 
 
 i 1000 
 
 z 
 
 X 
 
 «J 
 
 O 
 
 • I I 
 
 OS 1.0 
 
 MLRCURY-ALLOY RATIO 
 
 1.5 2.0 
 
 PACKED UNDE.R 1131 KILOS 
 
 Fig. 
 
 346. — Modification of Figs. 344 and 345 by further increase of packing pressure 
 to 1131 kg. per cir. cm. 
 
368 
 
 PROPERTIES OF FILLING MATERIALS 
 
 but the additional complications arising from the union of the mercury 
 with the alloy, and the conditions under which these alloys are com- 
 bined with mercury in the practice of dentistry. 
 
 Gray has shown (Figs. 344/ 345^ and 346^) that as the pressure in 
 packing is increased from 141 kg. to 1131 kg., the crushing resistance 
 in circular centimeters is raised from 800 kg. to 4600 kg. There seems 
 to be no doubt that the variations in the pressure used in packing 
 amalgam in the great variety of places where this material is used in 
 the practice of deatistry result in similar variations in strength. 
 
 a: 
 
 UJ 
 
 S 4000 
 O 
 
 o 3000 
 
 ^ 2000 
 
 1000 
 
 
 
 
 
 
 
 
 
 X 
 
 
 
 
 
 
 
 
 
 \ 
 
 
 
 
 
 
 
 
 < 
 
 K 
 
 
 
 
 
 
 
 
 
 \ 
 
 
 
 
 
 
 
 
 « 
 
 k: 
 
 
 
 
 
 
 
 
 N 
 
 
 
 
 
 
 
 
 
 t , 
 
 
 
 
 
 
 
 
 •I 
 
 
 
 
 
 
 
 
 K 
 
 -a^H*-, 
 
 »*a-«. 
 
 20° 4-0° 60° 
 
 TEMPERATURE CENTIGRADE 
 
 80° 
 
 Fig. 347. — Effect of temperature on crushing strength. Transition region shown by the 
 rapid fall in strength between 70° and 80°. 
 
 The same writer has shown that the temperature of the amalgam 
 when it is subjected to stress has a marked influence upon its resistance 
 to force (Fig. 347^). 
 
 When this feature of the behavior of amalgam was first published 
 it was questioned somewhat on account of the comparatively low 
 temperatures used for the tests, but as the work was checked up by 
 experiments it seemed to be no more cause for surprise than was the 
 discovery of the low temperatures at which alloys for amalgams would 
 
 1 Gray, Arthur W. 
 
 2 Ibid. 
 
 3 Ibid. 
 
 Ibid. 
 
NATURE OF AMALGAM ' 369 
 
 become annealed. As this is compared with the various processes in 
 nature which are known to be going on at equally low temperatures, 
 and with the known behavior of other materials at different tempera- 
 tures, it seems strange that other investigators had not observed this 
 phenomenon before. Hadfield, Dewar and Le Chatelier^ and others 
 have investigated the tensile strength and elongation of copper at 
 temperatures varying from —182° C. to 530° C. and found that the 
 tensile strength was approximately six times as much at the former 
 temperature as it was at the latter. They found the elongation was 
 approximately three times as much. The tensile strength of aluminum 
 has likewise been studied^ and found to be much less at elevated tem- 
 peratures. Several alloys of commercial interest have been studied 
 with similar results. There seems to be so much similarity between the 
 apparent behavior of amalgam at different temperatures and what is 
 known about the behavior of other metals that the phenomena shown 
 in Fig. 347 will probably be accepted. It is possible, however, that the 
 curve shown by Gray will be modified somewhat for the reason that 
 the 400 kg. per circular centimeter pressure used in making the fillings 
 for the tests seems somewhat higher than is permissible in practice. 
 When metals have been worked in the cold state or have been sub- 
 jected to high pressures their decrease in strength is more rapid as the 
 temperature rises than in those which have been cast and allowed to 
 cool. From this it seems likely that the curve shown may be modi- 
 fied to show a little less rapid change in crushing strength with rise 
 in temperature. 
 
 From the beginning of the use of amalgam it has been recognized 
 that the time devoted to trituration of the mercury and alloy had a 
 marked effect upon the strength of amalgam. With comparatively 
 simple instruments for the purpose of detecting differences in strength, 
 teachers and practitioners alike have been able to show that fillings 
 could be made to show little or no strength when there had been little 
 trituration of the mercury and alloy, and that as the trituration time 
 was increased, the strength increased rapidly to the maximum. With 
 this knowledge of the situation, the author carried on an appreciable 
 number of experiments to determine approximately, at least, how much 
 trituration was necessary in order to develop the maximum strength 
 of amalgam and stated in the former edition of this book that it 
 required from three to five minutes, depending upon the rapidity of 
 the operation. It should be obvious that one operator may leisurely 
 triturate the mercury and alloy while another may work rapidly and 
 as a result accomplish double the number of units of work. Recently 
 
 1 Law, E. F. : Alloys and Their Industrial Application. * Ibid, 
 
 24 
 
370 
 
 PROPERTIES OF FILLING MATERIALS 
 
 the matter of trituration time has been given further consideration 
 and found to be approximately as previously stated. It may be noted 
 that Fig. 348^ shows that the trituration may be carried on for six 
 minutes before the incipient setting begins to show a decline in the 
 crushing strength. Since the amount of annealing that was given 
 the alloy used for the tests and the rapidity of the operator are unknown, 
 it appears to the author there is a possibility that the person who 
 triturated the mercury and alloy for these tests worked a little slower 
 than the oue who made those for the author and as a result did not 
 
 4000 
 
 3000 
 
 2000 
 
 1000 
 
 O -^2 4 
 
 TRITURATION TIME IN MINUTES 
 
 1131 
 400 
 141 
 
 Fig. 348. — Gain in crushing strength produced by increasing trituration time. 
 
 reach a stage in the setting of the mass where the decline begins quite 
 so soon. 
 
 It seems quite probable, therefore, that six minutes is the maximum 
 time that will bring out the maximum strength. It should be kept in 
 mind in this connection that if the maximum time has been devoted to 
 trituration, the packing must be done very quickly. Inasmuch as 
 this is not always possible in the practice of dentistry, it is questionable 
 whether it is advisable to triturate the mercury and alloy which have 
 been fully annealed for a longer time than four and one-half or five 
 minutes. 
 
 1 Gray, Arthur W. 
 
NATURE OF AMALGAM 371 
 
 In arriving at accurate conclusions with respect to the strength of 
 amalgams it is assumed that the proper proportions of mercury and 
 alloy have been used. If in one instance too little mercury has been 
 used there will have been too little alloy dissolved in the mercury, and 
 the mass when set will be comparatively weak. If, on the other hand, 
 too much has been used and it has been left in the mass, the filling will 
 be comparatively weak, due to the presence of more mercury than is 
 necessary to react with the alloj^ used. By referring to Fig. 344, it 
 may be seen that the maximum strength is obtained when about 1.6 
 per cent, of mercury is used. It may also be seen that no further 
 increase of strength was observed by further increasing the percentage 
 of mercurj' and that the pressure was sufficient to remove the excess of 
 mercury, for no decline in strength is sho\\Ti as the proportions of 
 mercury reach 2.5 per cent. If in this case the pressure had been low 
 there would have been a decline of strength sho^Mi, as excess mercury 
 was retained in the filling. 
 
 It seems to be generally accepted that the age of a filling should be 
 given when statements regarding strength are made, for it is well 
 known that strength begins to develop as the setting progresses. In- 
 asmuch as the reaction curves previously given seem to indicate con- 
 tinuations of the setting process that begins as soon as the alloy and 
 merciu-y begm to combine, it is to be expected that variations in the 
 strength will follow variations in the reaction curve. It may be noted 
 that Gray has sho^Ti the strength of these amalgams at the end of 
 forty days. This is undoubtedly quite accurate for the pressures he 
 has used. For lower pressures, such as are common in inaccessible 
 places in the practice of dentistry, it may be expected that the maxi- 
 mum strength will not develop until at least three or four months 
 have elapsed. 
 
 It is well kno;^T^i that the heat treatment given to the cut alloy has 
 a marked effect upon the strength. When freshly cut particles of 
 alloy are combined with mercury the combination takes place so 
 rapidly that it is not possible to continue the trituration to a place 
 where the mass becomes fine grained for the reason that incipient 
 setting takes place. This mass appears to be composed of a cementing 
 layer of amalgam around the comparatively coarse alloy particles. 
 If the alloy be annealed the combination takes place less rapidly and 
 trituration may be carried on further, resulting in a mass in which 
 there are particles much smaller. The general effect of making the 
 combination of mercury and alloy slower seems to be to increase the 
 strength up to a certain point and then a continuation of the annealing 
 seems to cause a decline in the strength. The amount of annealing 
 that should be given to each formula varies with the composition of the 
 alloy and the mechanical treatment given it during the cuttmg process. 
 
372 PROPERTIES OF FILLING MATERIALS 
 
 Flow of Amalgam. — ^A solid metal can flow like a viscous fluid if 
 sufficient pressure is applied.^ The property seems to be different with 
 different metals and varies with different forms of the savie metal. 
 Some metals with a distinctly granular structure seem to flow less 
 than the same metal when in a less granular structure, though the 
 tenacity and elongation of the two forms may be nearly identical. The 
 differences in the rate of flow between different metals depend largely 
 upon their plasticity, by virtue of which they yield to the pressure and 
 allow the molecules to slip over each other and assume new positions. 
 
 If we subject a bar of pure silver or copper 3 mm. square to a force 
 of 200 kg. it will yield a very little soon after the pressure is applied, 
 then it will yield no more until the weight is increased. If we try a 
 similar block of tin in the same way we find that it yields much more 
 easily; 15 kg. will cause considerable change, and if we leave it under 
 this pressure without increasing it will continue to yield until the 
 greater part of the tin has flowed from between the points and been 
 reduced to a thin sheet. One writer^ has stated that this is proof that 
 tin is not only a softer metal but has a physical property totally dif- 
 ferent from any possessed by silver, the property of continuous flow 
 under a given pressure. This indicates the effect of tin and silver upon 
 flow, though it implies that the flow of tin is a peculiar property rather 
 than that it is a property of all metals, tin being one possessed of a 
 high rate of flow. 
 
 A hard metal like silver has an elastic limit wjiich must be exceeded 
 and the pressure maintained in excess if a continuous flow is produced, 
 while a soft metal like tin has practically no elasticity, and is therefore 
 capable of being changed in form with almost any pressure. The 
 composition of the alloy controls largely the property of flow, the hard 
 and elastic metals reducing it and the soft ones increasing it. The 
 effect of annealing upon flow depends upon the composition, some 
 formulae being affected more by annealing than others. Generally 
 speaking the softening of an alloy by annealing increases flow, although 
 with some formulse flow may be slightly decreased by annealing. 
 
 The manner of incorporating the alloy and mercury, percentage 
 of mercury used during amalgamation, the condition of the cut, or the 
 amount of mercury left in the filling modify flow, although apparently 
 not with regularity even in a given alloy. The least change in compo- 
 sition so modifies flow that each of these phases must be considered 
 separately with each formula. An excess of mercury left in the filling, 
 however, increases flow quite regularly, there being some exceptions 
 in the ternary amalgams, which are high in silver and low in tin. The 
 
 1 Hiorns: Mixed Metals and Metallic Alloys. 
 * Black: Operative Dentistry, vol. ii. 
 
NATURE OF AMALGAM 
 
 373 
 
 property of flow depends largely- upon the softness and absence of 
 elasticity, and is at its maximum in alloys known as low silver alloys, 
 Spheroiding of amalgams is a phenomenon associated with flow and 
 increase in volume. It has been held that amalgams possess a strong 
 tendency to become spherical in shape, due to the influence of mercury 
 which is spherical in shape when divided finely. This influence which 
 mercury is supposed to exert seems to be a misconception of the cause 
 of the tendency to spheroid. Mercury is spheroidal or globular in 
 shape when divided somewhat, the smaller the particle the more 
 nearly a sphere. There seems to have been a tendency to regard this 
 as a property peculiar to mercury. This is not true. The property 
 is possessed by other metals when in a fluid condition. 
 
 Fig. 349. 
 
 The above illustrations show a spheroided filling produced by an 
 alloy which increased in volume and flowed easily. It was composed 
 of silver, 49 per cent.; tin, 49.1 per cent.; zinc, 1.9 per cent. Fig. 350 
 shows the surface of a filling made from this plastic alloy and kept in 
 
 Fig. 351. 
 
 the thermostat at body temperature for eight months. The surface is 
 seen to be spheroided. Fig. 349 shows a companion filling like that of 
 Fig. 350, except that the walls of the test-tubes are highly polished, 
 this being accomplished by making the test-tube with removable 
 bottom, as seen in Fig. 351. It may be seen that the filling (Fig. 349), 
 
374 PROPERTIES OF FILLING MATERIALS 
 
 instead of spheroiding, has risen nearly as much at the borders as it 
 has at the center of the filHng. The filKng (Fig. 350) has assumed a 
 much more spheroidal surface than the one (Fig. 349), due apparently 
 to the walls of the cavity being purposely roughened. This spheroidal 
 tendency seems to disappear somewhat with alloys high in silver and 
 copper, these alloys possessing less flow. It has not been produced 
 to any extent in alloys which do not expand decidedly and flow com- 
 paratively easily, although irregular expansions and contractions appear 
 to produce in some instances bulged surfaces and in others concave 
 surfaces in alloys possessing little flow and expansion. 
 
 General Considerations. — Washing Amalgam. — ^Much importance 
 has been attached to the washing of the alloy particles during the 
 process of incorporation with the mercury. Such substances as dilute 
 acids, alcohol, ether, chloroform and sodium carbonate have been used, 
 but with doubtful value in many cases, for the reason that the pro- 
 fession has not mastered the technic of mixing the alloy and mercury. 
 The advantage of washing the alloy is to remove some of the metallic 
 compounds that have formed during the cutting process and annealing, 
 process, and by subsequent standing exposed to contaminating atmos- 
 pheres for some time. It has been stated that washing alloys increases 
 shrinkage, but this can be accounted for easily when it is considered 
 that practically all alloys had considerable shrinkage previous to 1895. 
 Since that time alloys have been made that possessed little shrinkage 
 and litte or nothing has been said about the effect of washing alloys. 
 Another disadvantage of washing alloys is that it is difficult to prevent 
 some of the material from becoming incorporated in the amalgam as a 
 foreign body, thus lessening the strength. If, however, the material 
 used for washing actually loosens the metallic coinpounds upon the 
 surface of the alloy particles, or if it dissolves them and they are then 
 well removed by rolling the amalgam mass into a thin sheet between 
 two pieces of absorbent material, the result will be a better solution of 
 the alloy in the mercury with a brighter color and better strength. 
 
 A still better plan than washing the alloy at the time of making a 
 mix with mercury is to wash it some time in advance. This is probably 
 better done by the manufacturer, though it may be desirable for the 
 dentist to do it if a quantity of alloy has become contaminated by 
 exposure after leaving the manufacturer. 
 
 One of the leading manufacturers has recently taken out a patent^ on 
 a process for washing and drying the alloy after it is cut and annealed. 
 It seems likely that hydrochloric acid in small quantities in alcohol 
 is used in this instance. 
 
 1 Alloy and Method of Purifying Same, Paul Poetschke, patent No. 1278744. 
 
NATURE OF AMALGAM 375 
 
 Thermal and Chemical Relations. — Amalgam, like gold and other 
 metals, is a conductor of thermal impressions. Just where amalgam 
 stands as a conductor of heat and electricity is not known, although 
 it can safely be placed quite near gold. The composition of the 
 amalgam will influence its conductivity. Any rise in temperature 
 will usually retard and a fall in temperature will increase conductivity, 
 although the resistance of alloys to conductivity does not always 
 behave in a manner that would be expected from the nature of their 
 constituents. Certain anomalies which are known to exist make it 
 seem possible that certain temperatures with certain formulae might 
 result in a variation from the general rule. Dental amalgams are 
 practically insoluble in the fluids of the mouth. The common solvent 
 found in the oral cavity, lactic acid, affects them only a little. There 
 is, however, a constant wasting away of many amalgams, due to the 
 formation of compounds which are soluble in the oral fluids or which 
 are worn off during mastication. Amalgams that are high in copper 
 furnish an example of the constant wasting which may be due to the 
 formation of the green basic carbonate in small quantities or salts 
 from the action of hydrogen sulphid and soluble sulphids. The two 
 principal classes of alloys now in use are not affected in this manner to 
 any appreciable extent. 
 
 There are probably no alloys in use which exert any particular 
 influence upon the tooth tissues except those high in copper or possibly 
 silver or tin. One or two alloys containing high percentages of copper 
 are heralded as great tooth preservers, not simply because they are 
 free from contraction, expansion and flow after insertion, but 
 because they possess "antiseptic properties." A critical examination 
 of them fails to reveal any reason why they should exert a marked 
 influence on account of their comparative insolubility. The action 
 of copper amalgam upon the tooth tissues, however, has been studied 
 by Miller, Fletcher, Witzel and others, and the general opinion seems 
 to be that it possesses antiseptic properties not possessed by amalgams 
 containing small percentages of copper. (See Copper: 1. Amalgam. 
 2. Cements.) 
 
 Copper Amalgam. — Copper Amalgam differs so markedly from all 
 other amalgams, both ui composition and behavior, that it deserves 
 separate consideration. The foregoing data apply only m slight 
 degree to copper amalgam. It is an alloy of copper and mercury and 
 may be made by adding freshly precipitated and washed metallic 
 copper to an excess of mercury until the solution is complete; the 
 excess mercury is then removed by compressing the mass in chamois 
 skin. The portion which does not pass through the chamois skin 
 is packed into molds and allowed to stiffen. The product may be 
 
376 PROPERTIES OF FILLING MATERIALS 
 
 purchased in the form of small tablets, which may be softened by heat- 
 ing slowly in a spoon (Fig. 352) after which it may be molded and 
 packed into the cavity. Many dentists have made copper amalgam 
 by grinding copper filings in a mortar with dilute acids and washing 
 with a variety of substances immediately before insertion of the 
 amalgam. A far better method, and one which yields a product of 
 greater purity and uniformity, has been suggested by Dr. E. C. Kirk. 
 It is done by precipitating the copper directly into the mercury by 
 electrolysis. "This may be done conveniently," says Dr. Kirk, "by 
 pouring a quantity of mercury into a suitable glass vessel — a small 
 battery jar, for example — and suspending a thick plate of copper, by 
 means of a wooden support, some distance above the surface of the 
 mercury. 
 
 Fig. 352. 
 
 "A saturated solution of cupric sulphate is then poured into the jar 
 until the copper plate is completely submerged. The cathode pole 
 of a battery or other source of electric current is then connected with 
 the layer of mercury and the anode with the copper plate. All of the 
 cathode electrode that is in contact with the cupric sulphate 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 main- 
 tained. The precipitation should be continued until the mercury is 
 saturated, which will be evidenced by the appearance of the character- 
 istic red color of the excess of copper at the cathode pole. 
 
 " When the saturation point has been fully reached the mass should 
 be washed, first in dilute hydrochloric acid and then in water, dried 
 and compressed, as is usual with this amalgam when prepared by the 
 ordinary process." Copper amalgam prepared in this manner changes 
 in volume very little, if at all, as a result of the union of mercury with 
 the copper, either in the mixing or subsequent to its insertion into the 
 oral cavity. The only known alteration in form that occurs is the 
 comparatively small one resulting from the thermal changes. It is 
 antiseptic. These two qualities make one of the best tooth preservers 
 now in use, although it has other qualities so undesirable as to exclude 
 
NATURE OF AMALGAM 377 
 
 its use in a great majority of cases. It turns almost black in most 
 mouths, has a peculiar metallic taste, is sometimes a marked cause of 
 voltaic disturbance, and if moisture through any cause enters between 
 it and the walls of the tooth the latter becomes discolored. Often, 
 although no visible leakage of the filling is apparent, there is discolored 
 tooth tissue, due probably to the absorption of the salts of copper into 
 the dentinal tubuli. Copper amalgam is not quite as indestructible in 
 the fluids of the mouth as other amalgams, as it readily forms salts 
 which are either dissolved or carried away by abrasion. This is com- 
 monly shown by a sort of cupping out of the surface of the filling. 
 
 Classification of Amalgams. — Amalgams may be divided into 
 classes according to the number of constituent metals. A binary 
 dental amalgam may be represented by copper and mercury or palla- 
 dium and mercury, each of which has a very limited usefulness in 
 dentistry. Some of the older alloys of silver, tin and mercury, such as 
 that designed by Dr. Townsend, represent what may be called a ternary 
 dental amalgam. Amalgams of silver, tin, copper and mercury, such 
 as designed by Dr. Flagg, may be said to be quaternary dental amal- 
 gams. This class is also represented by the so-called plastic amalgams 
 made since 1895-1896, and composed of silver, tin, zinc and mercury. 
 The high percentage silver amalgams, composed of silver, tin, copper, 
 zinc and mercury, may well represent a quinary amalgam. The terms 
 binary, ternary, etc., have not gained in popularity with the profession 
 in the last decade, although amalgams are in use representing each of 
 the classes mentioned. 
 
 Buying and Keeping Alloys. — The question, "Which is the best 
 alloy to buy?" is asked so often that it seems quite certain that the 
 profession in this particular does not exercise the same judgment with 
 which it selects other dental materials. It indicates quite clearly that 
 there is yet much mystery surrounding the purchase of an alloy. When 
 supplies the nature of which is not understood are required the majority 
 of the profession select them from a dealer who is believed to be reliable 
 in this respect and who is known to be wholly reliable in others. As a 
 rule the larger supply houses are best equipped for distributing uniform 
 supplies of all kinds, and most likely to secure the services of competent 
 men to manufacture their products. This is true in the manufacture of 
 alloys and should be used as a guide in their selection. Sometimes a 
 good product comes from a dealer who is not well nor favorably known, 
 but this is the exception rather than the rule. Alloys and cements above 
 all other products should be made and placed upon the market by com- 
 petent chemists if the dentist is to be rewarded for his work. The 
 practicing dentist should never attempt the manufacture of these 
 products himself without first spending considerable time preparing 
 
378 PROPERTIES OF FILLING MATERIALS 
 
 himself by learning the peculiarities of these products with special 
 apparatus built for the purpose. 
 
 Dentists, as a rule, are kept changing alloys by solicitous dealers 
 who advance this or that quality of their alloy as a cure-all. For 
 example, one dealer lauds his product as being superior because it 
 contains more silver than a like article made by another. Another 
 makes the same claims regarding the quantity of zinc in his product. 
 Others advance the argument that the manner of cut of their manu- 
 facture has much to do with the success attending its use, and so it is 
 with nearly every dealer. These arguments generally reward the 
 dealer with sales because dentists, as a rule, are not sufficiently 
 informed on the subject to enable them to judge the merits of the 
 products themselves. 
 
 It is true that some of the best manufacturers differ as to what con- 
 stitutes the "best alloy, all things considered," but, as a rule, the differ- 
 ence of opinion is an honest one rather than an effort on the part of the 
 producer to lessen the first cost of the article. This is shown by 
 several leading dealers' products, which are found to contain from 65 
 per cent, of silver to 68 per cent, of silver, yet each will claim to have 
 an alloy made after Dr. Black's plan, etc. The maker who uses 68 
 per cent, of silver knows that he obtains a little stronger filling, although 
 he is conscious of the fact that it works a little harder and sets faster 
 than one that contains only 65 per cent, of silver. On the other hand, 
 he who uses 65 per cent, of silver knows that his product works a little 
 more easily aad sets a little more slowly, although he is conscious that 
 it is a little weaker. The maker who uses only 65 per cent, of silver 
 probably considers it better to give the operator a little more time to 
 work than to have a little stronger filling. 
 
 The same is true of the quantity of zinc now used in high percentage 
 silver alloys. Some claim better and permanent light color in the mouth 
 as a result of the use of a little more zinc, while others admit a loss in 
 color as a result of its elimination, but claim to have a product more 
 permanent in form, as a rule. Neither disputes the other's claims, but 
 each places greater stress upon the distinctive qualities of his product 
 in contrast to those of his competitors. Thus it becomes a matter of 
 judgment which quality is of most importance. 
 
 The leading dealers' high percentage silver alloys are all good, well- 
 made, uniform products, and except for the difference mentioned, 
 they are nearly of equal value from a practical standpoint. Whether 
 an alloy contains 65 or 68 per cent, of silver is not a guide to the quality 
 of either. The same is generally true with the small quantities of zinc 
 now used, although it is quite generally understood that zinc, while 
 it improves color, facilitates change in volume subsequent to insertion 
 
NATURE OF AMALGAM 379 
 
 when used in large quantities. This is not so, however, if used in small 
 quantities. Dentists cannot rely upon the quantity of each or any 
 constituent as a guide to quality, although present knowledge of the 
 subject confines the qualities of each constituent for the best alloys 
 to the ranges stated. All things considered the high percentage silver 
 alloys are best, and should be chosen by dentists. 
 
 There are, perhaps, some places where the quick-setting properties 
 make the use of these alloys questionable, but, taken as a general rule, 
 dentists soon learn to open the orifice of the cavities and master the 
 manipulation of these quick-setting, stiff-working products. When 
 purchasing an alloy from a manufacturer who makes his product in 
 both filings and shavings the filings should be chosen. Shavings as a 
 rule, are too coarse and not of the proper shape to permit their being 
 dissolved readily in mercury. Not all manufacturers make their 
 products "cut in two forms." As some dentists demand them, the 
 maker sometimes can hold his trade by no other means than by 
 supplying shavings to those who want them. 
 
 Some makers of high percentage silver alloys make only one grade 
 of alloys as regards setting qualities while others make their product 
 in two or three grades. This, too, is usually done to catch trade, since 
 most makers are aware that if more than one grade is supplied, some 
 of the grades are imperfect products at the time of making. "Rapid 
 setting,'' "slower setting," and "slow setting" are terms used to desig- 
 nate these products. They are the same in composition, but have not 
 had the same amount of annealing. 
 
 Manipulation of Amalgam. — The high percentage silver alloys are 
 made by some manufacturers in two and three grades of setting. They 
 are of the same composition, cut just the same and marketed just the 
 same, except that some packages may be marked "slow setting," 
 some "rather rapid setting," and others "rapid setting." The differ- 
 ence in their production is in the amount of annealing given them, 
 annealing causing them to set more slowly, and their behavior is 
 usually more marked. 
 
 Alloys marked "rapid setting" will require much more mercury to 
 amalgamate them if they have not been in stock long enough to be- 
 come annealed. They will set so rapidly that it is difficult to pack 
 them properly, even in cavities of easy access, and almost impossible 
 to insert them where there is not ready access. The amount of expan- 
 sion that will take place subsequent to insertion is much greater with 
 improperly annealed alloys. The finished product is represented by 
 alloys marked "slow setting." Some manufacturers make their high 
 percentage silver alloys in one grade only. These alloys will have no 
 mark to designate their manner of setting. 
 
380 PROPERTIES OF FILLING MATERIALS 
 
 The alloy to be selected from general use is the finished product, 
 although the occasional use of "rapid setting" alloy when the patient 
 cannot be seen by the operator to finish the filling seems to be desirable. 
 It should be remembered that while alloys marked "rapid setting" 
 expand more than those marked "slow setting," contraction and 
 expansion are not controlled by the manipulation of them during 
 amalgamation and insertion. The operator may modify these move- 
 ments but he cannot control them, the controlling factors being com- 
 position and annealing. 
 
 In choosing an alloy it should be remembered that the property 
 which can be controlled most by the operator is strength, and even 
 then the alloy must be properly made or a strong filling cannot be 
 produced. 
 
 A strong filling cannot be made from a poor alloy, although a weak 
 filling may be made from a good one. The amount of alloy necessary 
 for the filling should be placed in a small ground glass or Wedgwood 
 mortar and ground with the required amount of mercury until the 
 mass becomes coherent enough to be turned into the palm of the hand 
 conveniently, after which it should be kneaded rapidly and vigorously 
 for from three to five minutes, depending upon the coarseness of the 
 cut, amount of annealing and composition of the alloy. 
 
 A complete union of the alloy and mercury cannot be effected at 
 ordinary temperatures. The operator must be guided in amalgamating 
 these alloys by the consistency of the mass. It should be fine grained 
 and smooth and tough enough to be rolled out into a long roll without 
 breaking before the mixing is discontinued. 
 
 The amount of mercury to be used with a given weight of alloy is 
 slightly more than the weight of the alloy. The proportions given by 
 most makers of high percentage silver alloys are, approximately: 
 alloy, 5 parts; mercury, 7 parts, by weight. These proportions are 
 as nearly correct as can be determined by experiment, although 7 
 parts of mercury will be found none too much for alloys marked 
 "rapid setting." The low percentage silver alloys of all grades will 
 require less mercury. It will usually be found necessary to use more 
 than equal weight of mercury for a given weight of alloy to make a 
 smooth, fine-grained mass. The amount of mercury to be used with a 
 given amount of alloy of known composition is a question which cannot 
 be answered unless the " condition of the cut" and the age of the alloy 
 are known. 
 
 All alloys require less mercury as they become annealed, hence the 
 proportions given by makers of alloys are correct for a comparatively 
 freshly made alloy only. 
 
 The older any alloy becomes, the more easily it works, the weaker it 
 
NATURE OF AMALGAM 381 
 
 is, and the less mercury it requires, although if properly made, it will 
 not contract appreciably. It may be noted that manufacturers having 
 similar products recommend slightly different amounts of mercury to 
 be used with a given amount of alloy. Some products may be marked : 
 " Use 5 parts of alloy with 7 parts of mercury;" "4 parts of alloy with 
 5 parts of mercury;" "9 parts of alloy with 11 parts of mercury," etc. 
 Chemical analyses show many of these alloys to be nearly identical 
 in composition, but there is some diflference in the "cut" of them, a 
 little difference in the amount of annealing, and probably some differ- 
 ence in the manner of casting and cooling, which accounts for the 
 variation of about 10 per cent, in the amount of mercury required. 
 The correct amount of mercury to be used during amalgamation does 
 not mean the amount of mercury to be left in the filling. It means 
 that a slight excess of mercury should always be used to start the filling, 
 and as soon as it is noticed it should be removed. Dr. Black has 
 stated^ that "it is certainly best to have just the right amount," but 
 in the same sentence states that " superfluous mercury does little harm 
 if removed as soon as noticed." 
 
 Dr. Black has remained practically silent on the subject of "per- 
 manency of form" or changes in amalgam subsequent to insertion. 
 Consistency of the mass seems to have been a prominent factor with 
 him. This is unquestionably a vital point in the packing process, 
 but an amalgam which packs nicely may be the most unstable kind. 
 
 The factor of supreme importance in the production of a stable 
 amalgam is a fairly complete solution of the alloy in the mercury. 
 This can only be produced by the use at all times during the amal- 
 gamation process of slightly more mercury than makes a mass of the 
 consistency to pack well. As soon as the mass begins to stiffen and 
 shows a tendency to set, any surplus mercury should be removed. 
 There is not even a remote possibility of an operator producing a true 
 amalgam out of modern high percentage silver alloys under ordinary 
 conditions. The best that can be done is to produce as much true 
 amalgam as possible around the undissolved particles of alloy and yet 
 keep the mass of a consistency to pack well. The latter often depends 
 upon the presence of a certain number of undissolved alloy particles. 
 
 Alloys low in silver and those high in silver that are very old may 
 dissolve so completely in mercury that the mass is too soft to pack 
 well. 
 
 The ultimate aim of the operator should be the production of a 
 mass of amalgam that is both stiff and tough and with the alloy well 
 into solution in the mercury. To accomplish this more mercury than 
 
 1 Operative Dentistry, vol. ii. 
 
382 PROPERTIES OF FILLING MATERIALS 
 
 is to be left in the filling should be used to start amalgamation. This 
 amount is stated on the packages of alloy, and is correct for freshly 
 made alloys. The alloy and mercury may be weighed on a balance or 
 turned out approximately correct by an experienced operator from the 
 containers. It is immaterial whether the exact amount of mercury is 
 weighed or not, as the operator never knows whether these proportions 
 are correct. It is convenient, however, to have them weighed in the 
 proportions the maker has determined for fresh alloys, since a little 
 mercury is easily removed during the amalgamation process if it be 
 found necessary. Earlier observations of the author led to the belief 
 that the alloy and mercury should be determined and weighed care- 
 fully, as in that way a mass was obtained of a consistency to pack 
 well; but later observations on the changes occurring in these bodies 
 subsequent to insertion lead to the belief that while the packing of an 
 alloy is a vital point, it is not of so much importance to the life of the 
 filling as to have the alloy worked with sufficient (though not enough 
 to make a sloppy mass) mercury at all stages up to and including the 
 packing. 
 
 After the alloy and mercury have been ground in a mortar, then 
 turned into the hand and worked vigorously for a few seconds, it should 
 be noted whether the mass is becoming sloppy. If it is, a little mercury 
 should be removed quickly between the thumb and forefinger. The 
 mass should not be put into pliers, chamois skin or muslin, as these 
 processes require too much time. Surplus mercury should be removed 
 quickly, or the mass stifi^ens so that the object of the operation is 
 partially or wholly defeated. The mass should be quickly turned into 
 the hand and again kneaded vigorously. If it again appears a. little 
 sloppy, remove some mercury as before. Do not remove too much 
 mercury or the alloy will not be anywhere near completely into solu- 
 tion. This process should be repeated three or four times, the last 
 time using all the pressure that can be exerted in removing the excess 
 mercury, so that the mass will be stiff enough to enable it to be packed 
 well. Three or four repetitions of this process usually consume from 
 three to five minutes and result in a tough, stiff and fine-grained mass. 
 
 The question might then be asked, "What is an excess of mercury?" 
 And it might be answered in a general way by saying that it is the 
 difference between the amount used to amalgamate the mass and 
 the amount that should be left in the filling. 
 
 Any amount of mercury left in the filling over and above an amount 
 which makes a stiff, tough and fine-grained mass of amalgam would, of 
 course, be regarded as superfluous. Every step in the amalgamation 
 process should be done rapidly, not allowing the amalgam to lie still. 
 If the mass lies still a few seconds it stiffens so much that the particles 
 
NATURE OF AMALGAM 383 
 
 of alloy are not broken down in the mixing and surplus mercury is 
 usually retained in the mass. The packing should be begun imme- 
 diately using flat-end serrated instruments. Several instruments have 
 been designed for the packing operation, but the consensus of opinion 
 seems to favor a flat-end or cup-shaped serrated instrument such as 
 shown in Chapter IV. 
 
 The round burnisher has been used with some degree of success, but 
 it has been proved that it does not give the maximum density or 
 adaptation. Pluggers used for foil fillings have been used somewhat 
 successfully, but they are too small for most places, and as a result 
 chop the amalgam mass to pieces and do not compress it. Great care 
 should be exercised in packing amalgam, as it is a most diflScult 
 material to adapt to cavity walls. Too little pressure results in a weak 
 filling. Too much pressure, such as that exerted by sudden blows 
 from a mallet, disturbs the whole mass, and as a result weakens the 
 filling. Heavy, steady pressure gives the strongest and best adapted 
 filling (Figs. 344, 345 and 346). The amalgam mass should not be 
 broken up any more than is necessary for convenience in placing it 
 into the different parts of the cavity. Much has been said in regard 
 to the part of the cavity in which to begin the packing, but it is doubt- 
 ful if any one method can be carried out in all cavities. 
 
 In all cases an effort should be made to wedge the amalgam, piece 
 after piece, between the opposing walls or between one wall and the 
 already condensed amalgam, finishing by wedging some amalgam 
 between the main mass and the cavity waHs. Experience will teach 
 how much force can be used in the wedging and what size of pluggers 
 will not chop the mass to pieces. Instruments of varying sizes must be 
 in readiness on the table, so that the operator has at his immediate 
 command instruments that will compress and wedge amalgam into 
 any pocket or crevice that may appear during the operation. Amalgam 
 to be packed properly must be stiff. Soft amalgam cannot be packed 
 to make even a fair margin when examined under the lens. It is in 
 this part of the work that the modern high percentage silver alloys 
 exceed all others, the low percentage silver alloys with no copper 
 scarcely deserving comparison. The cavity must have four walls if 
 any degree of compression is obtained. With the great variety of 
 matrices and matrix retainers provided by the manufacturers, together 
 with the facilities at the operator's command for making special 
 matrices, there is seldom occasion for the insertion of an amalgam 
 fining unless the cavity has four walls. (See Chapter IV.) 
 
 The cavity should always be filled to overflowing. Amalgam should 
 be packed with steady force and with as large pluggers as are consistent 
 with the operation, upon the orifice of the cavity and left until the 
 
384 PROPERTIES OF FILLING MATERIALS 
 
 mass has become hard before any of it is removed. After the mass 
 has hardened somewhat, surplus amalgam should be removed by carv- 
 ing toward the borders with sharp plastic instruments or excavators, 
 so that amalgam once packed along the margin and allowed to stiffen 
 will not be disturbed. Attention may be directed to the fact that this 
 can only be accomplished with the high percentage silver alloys. 
 
 Only very light burnishing should be done at the time of insertion 
 of an alloy lest the margins be disturbed. The matrix should be re- 
 moved with great care or it may disturb the margins or even the bulk 
 of the filling. An amalgam filling should be finished in the same 
 manner as a gold filling after it has "fully set." (See Chapter IV.) 
 
 If the filling be given its final finish prior to reaching its maximum 
 hardness the best finish cannot be obtained. Generally speaking, 
 forty-eight hours is sufficient to lapse between the insertion of amal- 
 gam filling and the time of giving its final finish, although a week is 
 better. 
 
 Amalgam fillings should be polished repeatedly. Not more than a 
 year should lapse after the insertion of an amalgam filling before it 
 should again have its margin polished and burnished. 
 
 Attention has been called to the fact that alloys have bulk changes 
 after as well as at the time of insertion. This often causes the filling 
 to appear spheroided, tilted, warped or otherwise distorted within a 
 year or two after insertion. Such fillings should be ground down with 
 small stones and the surface again finished. 
 
 During the packing operation mercury is often removed from the 
 amalgam mass and remains upon the surface. This is almost always 
 true if the operator uses very high pressure (Fig. 353),^ but is not 
 very marked if the mass has been worked properly and the excess 
 mercury removed by good, firm pressure just previous to packing, when 
 the regular amalgam pluggers are used. The use of quick blows, as 
 has been mentioned before, is bad practice, since it disturbs the 
 amalgam mass even when large pluggers are used. As fast as mercury 
 appears at the surface during packing it should be removed hastily 
 with an excavator or other instrument and more amalgam inserted 
 into the cavity. 
 
 If there is no easy access to the cavity, pressure enough to bring 
 mercury to the surface will seldom be exerted. This is also the case 
 if the matrix is not used. It is quite generally true that if there is 
 good access, if a little mercury is not removed during the packing the 
 pressure has been faulty. Gold foil, silver foil and tin foil have been 
 used to absorb the excess of mercury appearing at the surface of 
 
 1 Gray, Arthur W. 
 
NATURE OF AMALGAM 
 
 385 
 
 amalgam fillings, and little harm has probably resulted, although this 
 practice cannot be said to add to the qualities of the amalgam. New 
 alloys are formed upon the surface when anyone of these materials is 
 used, and experiments have proved that mercury and one metal do 
 not form an alloy having the most desirable qualities. 
 
 When tin foil is used to absorb mercury appearing at the surface a 
 soft non-crystalline, shrinking alloy results. Similar comment may be 
 made upon the use of the other materials, gold being no exception. 
 
 100 
 
 80 
 
 60 
 
 AO 
 
 20 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ^ 
 
 — j 
 
 — -_J 
 
 f 
 
 ' 
 
 i 
 
 , 1 
 
 1 — i 
 
 
 I- , 1 
 
 ^ 1 
 
 1 — 1 
 
 4 
 
 t~~ \ 
 
 M 
 
 
 f 
 
 f ■' 
 
 
 1 — ' 
 
 
 1 
 
 
 ' ■ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 141 
 
 o: o 
 
 400 ^ 
 
 . </5 
 
 1131 
 
 z u 
 2 ir 
 o u 
 
 1^ 
 
 Fig. 353. 
 
 2 4 6 8 
 
 TRITURATION TIME IN MINUTE.S 
 
 -Percentage of mercury in an amalgam filling is less when high pressure has 
 been used to pack it than when low pressure has been used. 
 
 Mercury which has appeared on the surface during the packing 
 provided the packing has been done with care, should be removed and 
 not used again without being redistilled. The affinity of such mercury 
 for other metals is probably weaker, even though it remains liquid. 
 
 It is possible that the presence of other metals in mercury may be 
 found to improve its different qualities, but it has not yet been done. 
 On the other hand, mercury which has been removed from amalgam 
 during packing has almost invariably been found to contain more tin 
 than other constituents. Dr. Black's later observations seem to con- 
 firm this,^ but in the same chapter he has stated that " if the alloying 
 
 1 Operative Dentistry, vol. ii. 
 
 25 
 
386 PROPERTIES OF FILLING MATERIALS 
 
 is a perfect combination, I have reason to believe that no one metal 
 will be dissolved more than another." It is a fact, however, that when 
 two metals are cooled, certain alloys of these metals may solidify first 
 and a more fusible alloy of these metals is left, and is known as the 
 eutectic alloy. It is a general rule that this defect is intensified when 
 four or five metals are used, as is the case in the production of dental 
 amalgam alloys. With these facts in view we may assume that an 
 ingot of alloy before it is cut contains quantities of globules or strata 
 of eutectics which may be more soluble as well as more fusible. Mer- 
 cury which has had ever so slight a contact with alloys should be 
 discarded, since it will pick up some of the alloy and have its affinity 
 partially satisfied. 
 
 CEMENTS. 
 
 The term cement formerly implied a material which was used to 
 unite two or more substances. This has required that the uniting 
 material should be plastic and highly adhesive and have other proper- 
 ties similar to those possessed by filling materials. During recent 
 years the possibility of obtaining these products in a more translucent 
 form has led to the development of several products known as cements, 
 because of their composition, which have little of the power of uniting 
 substances. Comparatively recently it has been shown that the 
 solubility of these products could be taken advantage of by the intro- 
 duction of compounds known to have antiseptic properties, and the 
 result has been the development of a class of cements not possessed 
 primarily of adhesive properties, but of antiseptic properties together 
 with a fair degree of adhesive properties. 
 
 The term cement as it is used today, therefore, is a much broader 
 term than it was formerly, and includes a variety of products which 
 may be grouped, for convenience, under three heads, namely, zinc 
 oxyphosphates, copper oxyphosphates and silicates. In each case 
 these products reach the practitioner of dentistry in the form of a 
 liquid which in all cases is an acid and a powder which may be one or 
 more inorganic compounds. When the acid is placed in contact with 
 the basic material the result is the formation of a new compound 
 accompanied by many of the usual phenomena that accompany the 
 union of the more common and simple acids and bases. For example, 
 heat is generated, strength is changed, solubility is changed and the 
 working properties are different. Inasmuch as most of the cements 
 now in use are the result of recent investigations, it is not possible to 
 give the same amount of information with respect to their properties 
 and behavior as is the case with amalgams. Only general statements 
 seemito be recorded. 
 
CEMENTS 387 
 
 Liquid Portion. — The liquids which are used in all three classes of 
 cements are compounds of ortho-phosphoric acid, aluminum hydroxid, 
 and water. The following is the result of an analysis^ of the liquid of 
 one of the leading zinc oxyphosphates : 
 
 Orthophosphoric acid (85 per cent, acid) 79.00 per cent. 
 
 Aluminum hydroxid 10.00 " 
 
 Water 11.00 
 
 100.00 
 
 A few of these cements may be found to contain small quantities of 
 zinc oxid, and one or two compounds of iron probably in phosphate 
 form, and still others a little copper, also probably in phosphate form. 
 Possibly some of the older products may be found that contain alkaline 
 modifiers in the liquid, but it seems unlikely since practically all 
 investigators report the use of aluminum phosphate as the best modifier 
 and partial neutralizer of the ortho-phosphoric acid for use with 
 zinc oxid. One ^\Titer2 reports the use of the oxids of calcium 
 strontium, beryllium, zinc, and aluminum in solution in the ortho- 
 phosphoric acid as the liquid for the silicates. The introduction of 
 new products containing these compounds confirms this report. From 
 this it seems that it is quite probable that the composition of the 
 liquid for the silicates may be changed eventually into a more complex 
 compound than the one most desirable for use in the formation of a 
 zinc oxyphosphate. 
 
 About the only generally accepted effect that is recorded with 
 respect to metallic modifiers in the ortho-phosphoric acid is that 
 aluminum phosphate so modifies the acid that less heat is generated 
 when the liquid and powder are brought into contact. Improvements 
 in the physical properties of dental cements of several years ago, 
 including the property of setting promptly in the presence of moisture, 
 are probably due in a degree to the presence of alummum phosphate 
 in the liquid. 
 
 Much the same may be said in regard to reliable information con- 
 cerning modifications of the acid by the addition of water. Ortho- 
 phosphoric acid is ordinarily known as a colorless, odorless syrup, 
 with a specific gravity of 1.7 and containing from 83 per cent, to 85 
 per cent, of phosphoric acid (H3PO4). 
 
 In chemistry, however, it is known as a translucent, very deliques- 
 cent soft solid, with a specific gravity of 1 .88, containing nothing else. 
 
 It should be obvious, therefore, that the 100 per cent, acid is not 
 in a form suitable for combination with a prepared powder. The 
 
 1 Ward, Marcus L. and McCormick, R. M.: Jour. Nat. Dent. Assn., 1915. 
 
 2 Voght, C. C: Jour. Nat. Dent. Assn., April, 1918. 
 
PROPERTIES OF FILLING MATERIALS 
 
 85 per cent, acid is in a much more favorable form, but it has been 
 proved less desirable from many standpoints than a still more dilute 
 and partially neutralized acid such as previously given for use in the 
 formation of a zinc oxyphosphate. The acid with a greater dilution 
 not only acts as a better solvent, but the water apparently plays an 
 important part in the chemical reactions with the powder resulting in 
 beneficial changes in physical properties of the product after it has set. 
 With certain cement powders the addition of a small percentage of 
 water to the phosphoric acid will hasten the setting while with others 
 the subtraction of water will retard the setting. This should be kept 
 in mind as well as the fact that phosphoric acid is deliquescent, for a 
 cement liquid may be nicely balanced with respect to water content 
 when it leaves the manufacturers' hands and later become unbalanced 
 upon exposure to the air, with marked changes in properties. An 
 atmosphere such as exists in a steam-heated room in the winter months 
 is usually dry. If a bottle of cement liquid be left exposed to such an 
 atmosphere it may lose from 10 per cent, to 20 per cent, of the water 
 content. If, on the other hand, the bottle be left exposed in a room" 
 that is warm and saturated with moisture, such as frequently happens 
 in rainy weather, the liquid may take up as much as from 1 per cent, 
 to 4 per cent, of water. Such changes have been shown to produce 
 marked changes in the properties of the cement, and should, therefore, 
 be guarded against in every way possible. 
 
 Powder Portion. — Zinc-oxyphosphates. — For many years zinc oxid 
 has been regarded the most suitable single constituent to combine with 
 modified phosphoric acid to produce a dental cement. Earliest obser- 
 vations, however, showed that unmodified zinc oxid did not yield a 
 cement that possessed as many desirable properties as zinc oxid which 
 was modified by either calcination of the zinc oxid or combining some 
 other compound with it. When unmodified zinc oxid combines with 
 phosphoric acid, or the prepared phosphoric acids now in use, the mass 
 sets too rapidly, making it impossible to make a smooth mass. The 
 mass is also less adhesive, weaker and more soluble. Many of the 
 earlier cements were made from plain zinc oxid, slightly pigmented, to 
 produce different shades, though they failed to meet the demands 
 placed upon these products. As the cements have been developed 
 to meet more of the demands on these products, more and more 
 modification of the zinc oxid has taken place. Among the .first modi- 
 fications to be adopted was calcination of the zinc oxid. As zinc 
 oxid is heated it becomes fused and takes on the appearance of 
 powdered glass or powdered silica, turns slightly yellow in color, is less 
 soluble, becomes much less flocculent and reacts with phosphoric acid 
 much less rapidly. Its chemical composition does not change but it§ 
 
CEMENTS 
 
 389 
 
 physical composition is markedly different, and when combined with 
 phosphoric acid or a prepared phosphoric acid the result is quite 
 different than when used unmodified. Another method of modifying 
 zinc oxid for use in dental cements consists of dissolving zinc oxid in 
 nitric acid and subsequently evaporating to dryness. The zinc oxid 
 thus produced from the nitrate is quite similar to zinc oxid 
 prepared by calcination, except that in this instance the particles of 
 zinc oxid are in a definite form. If the nitration process has been 
 carried out carefully, practically every particle seems to be of the same 
 
 1. Heating or nitration practiced by all manufacturers. 
 
 2. Fineness of comminution practiced by all manufacturers. 
 
 Cement pow- f Bi203 (used by Caulk, Ames, Smith 
 
 der is zinc (a) To improve I and Fleck). 
 
 oxid (ZnO) properties | MgO (used by Caulk, White, Smith 
 
 modified by I and Fleck). 
 
 (b) To color the | MnOo (black). 
 powder \Fe203(red). 
 
 3. Addition of 
 other com- 
 pounds 
 
 (c) 
 
 To add an- 
 tiseptic 
 properties 
 
 f CuO (black) 
 
 Ci (i 
 
 CuaO (red) 
 
 CU2I2 (white) 
 
 CuSiOs (greenish- 
 blue) 
 
 AgCl (white) 
 
 AgsPOi (yellow). 
 Both turn black 
 on exposure to 
 light. 
 
 99% Ames. 
 25% Caulk. 
 25% Fleck. 
 
 8% Caulk. 
 
 2% Caulk. 
 
 2% Smith. 
 
 2% S. S. 
 2% S. S. 
 
 White. 
 White. 
 
 size and shape, while with the calcination process the particles may be 
 of all sizes and shapes. As shown in the foregoing chart, both of these 
 processes are adaptable to practically all manufacturers' products 
 which, as a result of the combination of zinc oxid and phosphoric acid, 
 are known as zinc oxyphosphates. 
 
 By referring to the chart on cement powders it may be observed also 
 that zinc oxid may be modified in a third way, namely, by the addition 
 of other compounds. The first class of compounds is added for the 
 purpose of improving the color, the second to change the color and the 
 third to add antiseptic properties. 
 
 The principal compounds that have been found to be desirable 
 in modifying zinc oxid for cement powders are bismuth trioxid and 
 magnesium dioxid. Just what part these compounds play in the 
 cement-making process has not been recorded and the author has done 
 comparatively little work on them.^ 
 
 The limited work done by the author on the influence of bismuth 
 trioxid tends to show that it is added principally for the purpose 
 
 1 Ward, Marcus L., and McCormick, R. M.: Jour. Nat. Dent. Assn., November, 1915. 
 
390 PROPERTIES OF FILLING MATERIALS 
 
 of making a smoother mass. It does not appear that the bismuth 
 compound sets when combined with a prepared phosphoric acid but 
 produces a smooth, oily appearing mass, which remains in a plastic 
 state. It would seem from this that bismuth trioxid exerted a retard- 
 ing influence upon the rate of setting. While nothing definite is 
 recorded with respect to the influence of magnesium dioxid upon the 
 cement mass, it is to be expected that it plays a very important part 
 in the hydration process, for its behavior alone and in combination 
 with other compounds is well known. 
 
 Examination of the various products in the market reveals that in 
 some instances something has been added to the zinc oxid, magnesium 
 dioxid, bismuth trioxid compound to color it. Zinc oxid is white before 
 it has been heated or nitrated and yellow after either treatment. 
 Bismuth trioxid is a citron yellow compound and magnesium dioxid 
 is a white compound. When the three are combined it is obvious that 
 the result is likely to be white or yellow in proportion to the amount 
 of calcination given to the zinc oxid; the amount of heat applied to 
 the mixture of bismuth trioxid, zinc oxid, and magnesium dioxid; and. 
 the percentage of bismuth trioxid used. 
 
 The white and yellow powders thus produced may be converted 
 into various shades of gray, including greenish gray, by the addition 
 of very small quantities of a black compound. The author has repeat- 
 edly found one manufacturer's product to contain manganese dioxid 
 in the gray powders and has found upon experiment that as low a 
 percentage as 0.20 of this black compound will produce the shades of 
 gray and greenish gray. 
 
 The author has also repeatedly found some of the brown and reddish- 
 brown powders to be colored with ferric oxid. This appears to be the 
 only other coloring matter than manganese dioxid necessary to produce 
 the various shades of zinc oxyphosphates now in the market, which 
 are at present limited to shades white, yellow, gray and brown. 
 
 Copper. — Oxyphosphates (Antiseptic Cements). — ^The third class of 
 compounds added to the zinc oxid is for the purpose of adding anti- 
 septic properties, and, as may be noted from the chart, is limited at 
 present to compounds of copper and silver, both of which, for a long 
 time, have been known to possess antiseptic properties largely in pro- 
 portion to the percentage of the copper or silver compound added. 
 Four compounds of copper have been found in present products; one 
 is black (cupric oxid), one red (cuprous oxid), one white (cuprous 
 iodid) and one greenish-blue (cupric silicate). Recently two com- 
 pounds of silver have been introduced, one of which is white (silver 
 chlorid) and one yellow (silver phosphate) . With the exception of the 
 first product marketed by the W. V. B. Ames Company containing 
 
CEMENTS 391 
 
 practically all cupric oxid, all of the leading cement powders in the 
 market which have compounds of copper or silver added for the pur- 
 pose of adding antiseptic properties are modifications of the regular 
 cement powders. The first product shown contains cupric oxid, with 
 a very small quantity of a compound of cobalt, and is placed in the 
 group of modifiers of zinc oxid only for the purpose of showing at a 
 glance those cement powders which have varying degrees of anti- 
 sepsis. By the total elimination of the zinc oxid, bismuth trioxid, and 
 magnesium dioxid the maker of this product has a material which 
 represents the maximum in germicidal efficiency. All the other 
 products shown may be treated as ordinary cement powders which 
 have had added to them a copper or silver compound for the purpose 
 of making them more antiseptic than the ordinary cement powder is. 
 It may be noted that these products have been used in quantities 
 ranging from about 2 per cent, to about 25 per cent. It may be noted 
 also that the compounds of copper and silver, in the quantities used, 
 result in the production of three classes of cement powders with respect 
 to color, one black, one red and one light. 
 
 The class of light copper cements may contain any one of the last 
 four compounds shown in the chart on cement powders. This class of 
 cements is not light in color on account of the original color of the 
 copper or silver compound, but because there is not a sufficient quan- 
 tity of the silver or copper compound contained in this class of anti- 
 septic cements to turn the cement mass into a dark color. Both of the 
 copper and both of the silver compounds shown which, when intro- 
 duced into a cement powder, are comparatively light in color, are 
 capable of turning almost, if not quite, black upon exposure. The 
 only way, therefore, that is known by which a class of copper or silver 
 antiseptic cements may be made is to keep the percentage of copper or 
 silver compound so low that when they have turned dark they will 
 not make the mass very dark. 
 
 It seems that with one or two exceptions, compounds of copper and 
 silver are added to the ordinary cement powders in quantities ranging 
 from about 2 per cent, to about 25 per cent., resulting in the production 
 of three classes of compounds with respect to color. Because the ques- 
 tion of antisepsis is of principal importance, and because of the more 
 general use of compounds of copper than of silver for the purpose of 
 obtaining antisepsis, these products have been designated as copper 
 oxyphosphates to distinguish them from the ordinary cements known 
 as zinc oxyphosphates. The general practitioner of dentistry has fur- 
 nished to him by the manufacturers of dental products these three 
 colors of copper oxyphosphates, some of which have very little more 
 antiseptic value than the ordinary cement^ while others have decidedly 
 
392 
 
 PROPERTIES OF FILLING MATERIALS 
 
 more, depending upon the quantity of copper or silver present and the 
 solubihty of the cement after it has hardened. It is to be expected 
 that the dental profession will undertake to determine what degree of 
 antisepsis is necessary in these products in order to maintain a satis- 
 factorily hygienic condition on, and adjacent to, many of the restor- 
 ations retained in the mouth by cementation. At the present time, 
 however, practically all that is recorded regarding antiseptic cements is 
 by the manufacturers of dental materials, and is so conflicting in sub- 
 stance^ that it is of little value to the average general practitioner of 
 dentistry. 
 
 The first of the articles,^ 3 4 56 ^^s written in 1914 by W. V. B. 
 Ames, who is the maker of the first product shown in the chart. This 
 product differs from the others by having its germicidal agent the 
 principal cement-making material. In this article the writer speaks of 
 the impregnation of a cement powder with cuprous iodid as " a senseless 
 temporary expedient," and designates his product as the "real oxy- 
 phosphate." Since the appearance of this article several others have 
 appeared apparently, in most instances, as a defence of the procedure 
 which Ames condemns. Among other things, Poetschke speaks very 
 highly of cuprous iodid, but does not say that the product marketed 
 by Ames is not more antiseptic. Smirnow's work leads to the con- 
 clusion that cuprous oxid is the most germicidal, while Bacon's work 
 implies that all of the copper cements are sufficiently germicidal. 
 Quite recently the S. S. White Dental Manufacturing Company has 
 published a statement that their experience with these products has 
 caused them to eliminate compounds of copper from consideration. 
 
 This company has sent out some literature, with the following chart, 
 to show the reason for the use of silver compounds instead of the more 
 generally used copper compounds: 
 
 O -- V X 
 
 X * 
 
 
 
 Comparative tooth 
 
 
 
 
 
 and cement dis- 
 
 
 Comparative 
 
 Necessary for 
 
 
 coloration in effi- 
 
 
 germicidal 
 
 eflaciency. 
 
 
 cient percentage 
 
 
 strength. 
 
 Per cent. 
 
 Natural color. 
 
 strength. 
 
 Copper oxid (black) 
 
 100 
 
 50 
 
 Jet black 
 
 100 
 
 Copper oxid (red) 
 
 100 
 
 50 
 
 Red 
 
 100 
 
 Copper silicate 
 
 100 
 
 30 
 
 Green white 
 
 40 
 
 Copper iodid . 
 
 350 
 
 30 
 
 Light brown 
 
 35 
 
 Silver chlorid 
 
 3200 
 
 2 
 
 White 
 
 
 
 Silver phosphate 
 
 . 10400 
 
 1 to 2 
 
 Light gray 
 
 slight 
 
 Paul Poetschke,^ a chemist for the L. D. Caulk Company, states 
 that his results show that silver cements are not as efficient as most 
 
 1 The reader is referred to an article on this subject in the Dental Review for August, 
 1916, Marcus L. Ward. 
 
 2 Ames, W. V. B.: Dental Review, 1914. 
 
 * Poetschke, Paul: Jour. Indus, and Engin. Chem., 1915. 
 
 * Smirnow, M. R. : Dental Cosmos, 1915. 
 6 Bacon, Raymond F.: Ibid, 1916. 
 
 6 Poetschke, Paul: Ibid., 1916. ' Caulk Scientific Bulletin No, 1. 
 
CEMENTS 
 
 393 
 
 of the copper cements, and claims to be able to obtain an efficiency of 
 only 72 per cent, to 80 per cent, after fifteen minutes' exposure. In 
 the same contribution and in the following chart^ he shows that an 
 efficiency is obtained with the use of copper cements as high as 100 
 in the same length of exposure. 
 
 RECENT GERMICIDAL EFFICIENCY TESTS OF SILVER CEMENTS, 
 
 Sample. 
 S. S. White silver cement A 
 S. S. White silver cement B 
 S. S. White zinc cement 
 
 No. of living bac- 
 teria per c.c. just 
 before addition of 
 1 gram of sample. 
 
 After exposure 
 of 15 minutes. 
 
 Per cent, germicida 
 
 efficiency after 
 
 exposure of 
 
 15 minutes. 
 
 21,110,000 
 
 5,830,000 
 
 72.3 
 
 28,300,000 
 
 5,380,000 
 
 80.9 
 
 21,510,000 
 
 21,450,000 
 
 0.3 
 
 GERMICIDAL EFFICIENCY, CRUSHING STRENGTH, AND RETROGRESSION 
 IN STRENGTH IN SALIVA. 
 
 Sample. 
 
 Percentage of germicidal efficiency Crushing strength in saliva 
 after exposure of after exposure of 
 5 min. 15 min. 1 hour. 1 day. 7 days. 28 days. 
 
 Percentage 
 
 retrogression 
 
 in strength 
 
 in saliva. 
 
 1 . . 
 
 . . 0.0 
 
 66.6 83.3 
 
 970 903 
 
 797 
 
 17.8 
 
 2 . . 
 
 . . 99.4 
 
 100.0 100.0 
 
 595 755 
 
 833 
 
 0.0 
 
 3 . . 
 
 . . 97.1 
 
 100.0 100.0 
 
 788 800 
 
 918 
 
 0.0 
 
 4 . . 
 
 . . 96.0 
 
 100.0 100.0 
 
 935 1000 
 
 788 
 
 21.2 
 
 5 . . 
 
 . . 10.0 
 
 96.0 98.0 
 
 280 270 
 
 
 
 100.0 
 
 6 . . 
 
 . . 0.0 
 
 96.4 97.1 
 
 530 570 
 
 705 
 
 0.0 
 
 These two charts are quite indicative of the condition of the dental 
 literature with respect to antiseptic cements. Obviously they do not 
 agree, nor do they mention the question of relative solubility. The 
 authors of both charts refer rather briefly to solubility in their con- 
 tributions but do not include data on this property. Without these 
 data it is very difficult to draw conclusions of value in the practice of 
 dentistry. 
 
 It seems to be generally acknowledged that all cements are antiseptic 
 while in the plastic state, due to free phosphoric acid and acid phos- 
 phates. The free phosphoric acid and acid phosphates are soon fixed 
 through the chemical combination with the basic constituents of the 
 powder, and through occlusion in the set mass of cement. This tran- 
 sition from the plastic to the hardened state is of short duration, and 
 coincident with it there is a marked change in the physical and chemical 
 properties of the cement. 
 
 It should be obvious, therefore, that if prolonged germicidal action 
 is to obtain the hardened cement and not the plastic cement must 
 furnish it. If the hardened cement were wholly insoluble there would 
 be no germicidal action even though it contained large quantities of 
 
 1 Jour. Engin. Chem., No. 4, viii, 308. 
 
394 PROPERTIES OF FILLING MATERIALS 
 
 germicidal compounds. On the other hand if the cement be somewhat 
 soluble the germicidal compounds will be slowly released. If two 
 cements possess equal solubility germicidal efficiency will depend upon 
 the presence of potent germicides, but if they have unequal solubility 
 the one with the less solubility will be less efficient as a germicide. The 
 question that at once arises in the mind of the practitioner of dentistry 
 is which is the better of the two. No definite answer can be made 
 until more definite knowledge regarding the degree of germicidal 
 efficiency necessary under the varying mouth conditions is known. 
 In the light of our present knowledge of the far-reaching effects of 
 pericemental infections, and in view of the demands now being made 
 for their prevention, it seems that whenever there is a question between 
 solubility and germicidal efficiency a proper degree of germicidal 
 efficiency should be given the preference if the cement is located where 
 it is in contact with susceptible tissue. This question, however, is not 
 likely to be of much interest to the practitioner of dentistry for the 
 reason that most manufacturers prefer to increase the quantity of 
 germicidal compound or select a more potent one than to increase 
 solubility for the purpose of making their cement more germicidal. 
 Some manufacturers make two or three antiseptic cements so that a 
 given solubility may be preserved and at the same time have a variety 
 of germicidal efficiencies. 
 
 It is to be hoped that in the near future more data will be available 
 on what constitutes the proper degree of germicidal efficiency, for, as 
 may be seen, the chart shows a variety of opinions expressed in the 
 manufacture of a variety of products with no information as to the 
 places where they are indicated. It seems safe to prophesy a very 
 limited use of the copper cements containing only about 2 per cent, of 
 a copper compound (light copper cements). As a class they seem not 
 much more germicidal than the ordinary cements for general use. 
 The manufacturers of some of these products claim that they are 
 sufficiently germicidal and that they will not discolor in the mouth. 
 The claim of sufficient germicidal efficiency is not based upon proof 
 that is known to be reliable. The claim that they will not discolor in 
 the mouth is perfectly justifiable because any light compound of copper 
 when oxidized into cupric or cuprous form, thus becoming black or red, 
 will not discolor cement or tooth appreciably when used in only 2 
 per cent. 
 
 One manufacturer furnishes a small bottle of cement powder con- 
 taining 10 per cent, of cuprous iodid with the ordinary product of the 
 company, Instructions accompany the package advising the use of 
 as much of the cuprous iodid with the ordinary cement powder as is 
 thought necessary. This allows the practitioner of dentistry to obtain 
 
CEMENTS 395 
 
 any percentage of cuprous iodid up to ten, and, in principle, appears 
 to be more in harmony with modern therapeutics than the adoption of 
 fixed percentages. 
 
 It may be possible, however, to determine upon fixed percentages 
 that will meet the demands of average cases. It seems at this time that 
 if this course be adopted it will not be necessary to manufacture 
 products containing less than 5 per cent, of cuprous iodid or its equiv- 
 alent, for as the subject is studied, more and more evidence accumu- 
 lates to show that the light copper cements containing about 2 per cent, 
 of copper are comparatively inefficient as germicides. 
 
 Silicate Cements. — Comparatively recent improvements in the 
 zinc oxyphosphates and the copper oxyphosphates have stimulated 
 investigation with the use of compounds which would yield products 
 which were more translucent than were obtainable with zinc. The 
 efforts of the manufacturers have been directed toward the development 
 of a product that would have most of the properties of the zinc cement 
 and at the same time possess the additional property of translucency. 
 At the present stage of these efforts such materials as silicon dioxid, 
 calcium oxid, aluminum oxid are used to form a powder which, when 
 mixed with a liquid composed of phosphoric acid and water and metallic 
 oxids, sets in much the same manner as the zinc cements. 
 
 The general use of silicon dioxid and the similarity between these 
 products in translucency has apparently led to the adoption of the 
 name silicate cements. 
 
 On account of the recent development of these products to a place 
 where they were suitable for a trial in practice, little reliable informa- 
 tion is available. In fact, only two writers,^ ^ have attempted to reveal 
 the information that is possessed by the manufacturers. A few others 
 have written at some length, but have revealed little. 
 
 Voght claims that in addition to the constituents mentioned it is 
 necessary to add some additional components, such as fluorids, in 
 order to aid in fusing at a low enough temperature to keep the alumi- 
 num oxid in such a condition that it is chemically active while the 
 mass remains translucent. 
 
 He also states that the oxids that are used in solution in the phos- 
 phoric acid and water are aluminum, beryllium, calcium and zinc. It 
 is assumed that not all of these oxids are used in any one liquid. Pro- 
 bably one or two are used, making the liquid not much different from 
 the liquids used for the production of the zinc cements, so far as con- 
 stituents are concerned. The same writer states that non-metallic 
 oxids or acid anhydrids, as, for example, the oxids of phosphorus, 
 
 1 Voght, C. C: Jour. Nat. Dent. Assn., vol. v. 
 
 - Poetschke, Paul: Jour. Indus, and Engin. Chem., April, 1916. 
 
396 PROPERTIES OF FILLING MATERIALS 
 
 boron and titanium, may also be present in the powder portion. From 
 this it may be seen that these products are very complex and little 
 understood, or that those in possession of information are not inclined 
 to reveal it. In either case it does not seem possible to discuss the 
 subject except in a very limited way. 
 
 It seems to be common clinical observation that the silicate cements 
 are more translucent and more insoluble than the zinc cements, and 
 that, as a class, they are less adhesive, less tough and less hydraulic. 
 
 Some Properties Common to all Cements. — It should be obvious 
 that each class of cements has one or more properties developed to 
 a greater degree than other classes which are intended to be used 
 for other purposes. For example, a zinc oxyphosphate that was not 
 quite adhesive and possessed of a high degree of hydraulicity would 
 not be generally accepted for the reason that such cements are used, as 
 a rule, for the retention of inlays, crowns, bridges, bands, etc. In 
 accordance with the needs, the manufacturers develop these two 
 properties to a higher degree than they do with the other cements. 
 It should be equally obvious that a copper oxyphosphate or silver 
 oxyphosphate must have a higher antiseptic value than other cements 
 or there would be little reason for their manufacture. Likewise, sili- 
 cate cements should be more translucent than other cements or there 
 would be little demand for them. 
 
 Among the properties which are most desired in any dental cement 
 are: insolubility, constancy of volume, high resistance to stresses, 
 hydraulicity, adhesion, density, non-porosity. In addition it has been 
 pointed out that some cases demand a cement which is antiseptic and 
 some demand one that is translucent. 
 
 Among other properties which are usually taken into consideration 
 by the manufacturer are : heat generated during and subsequent to the 
 insertion of the cement into the tooth, toxic action on the pulp, rate of 
 setting and permanency of color. 
 
 It does not appear that present knowledge of chemistry and physics 
 will permit the production of a cement which possesses all of these 
 properties developed to a degree desired by dentists, so the manu- 
 facturers have done the best possible to meet all the demands placed 
 upon these products rather than to develop one or two properties 
 to the exclusion of others. If it were not quite necessary to have dental 
 cements of certain colors and have them set at a given rate it might be 
 possible to produce a dental cement that is as insoluble as some of the 
 commercial cements. To ignore color and rate of setting would render 
 some cements worthless in the practice of dentistry. The situation is 
 much the same regarding other properties. A dental cement must pos- 
 sess properties which are acceptable from several standpoints and will 
 
CEMENTS 397 
 
 not be useful if the varied demands of dentists upon these products 
 have not been taken into consideration by those who produce them. 
 
 Solubility. — One of the properties which all cements should possess 
 is a reasonable degree of insolubility, for in few instances in the practice 
 of dentistry is it practicable to completely prevent these products from 
 coming into contact with the saliva. At the present time no reliable 
 standard of insolubility has been established except that of clinical 
 observation. Dentists usually are able to observe whether cements 
 remain in position a reasonable length of time without loss of mass. 
 In comparison with metallic fillings they are seen to be the more sol- 
 uble of the two. In comparison with one another cements are seen to 
 be more soluble in some cases than in others. This may be due to the 
 composition and manufacture of the cement, or to the greater solvent 
 action of the saliva in some cases than in others, or to the manipula- 
 tion given the cement. 
 
 A cement which has been so manufactured that it is more soluble 
 than another when used under the most favorable conditions cannot 
 be improved much by the manipulation, nor will the media in which 
 it is placed improve its inherent solubility. 
 
 A cement which is known to be one of the most insoluble may show 
 much more loss of material in some cases than others, even though 
 the abrasion on the two has been equal. This is due to differences in 
 the solvent power of the saliva. More than a decade ago Joseph Head^ 
 pointed out the restraining power of saliva upon lactic acid and other 
 substances. He showed that a 1 to 500 lactic acid and water may in 
 some instances turn tooth enamel white in one-half an hour, while in 
 other cases it may not turn it white in several weeks and yet the latter 
 solution would turn blue litmus red and possess an acid taste. He also 
 showed that the saliva of an individual may change from time to time. 
 
 Dr. Kirk^ has called attention to the possibility of mucin being a 
 protective element in the saliva which prevents the action of dilute 
 acids upon the teeth. He has also called attention to a quite analogous 
 phenomenon, in which he showed that both acid and basic sodium 
 phosphate may exist in the same saliva and not be neutralized by each 
 other. 
 
 With further reference to the solubility of cements it should be 
 remembered that debris and food particles may restrain the action of 
 acids in much the same manner as mucin or other constituents of saliva. 
 
 Inasmuch as calcination or nitration of zinc oxid lessens its solubility, 
 it is natural to expect the yellow cements to be more insoluble than 
 the very light ones. It is possible, however, to make a very light 
 
 1 Pental Cosmos, 1908. 2 Jbjd,, Hi, 735. 
 
398 PROPERTIES OF FILLING MATERIALS 
 
 cement yellow by heating it with the bismuth-tri-oxid that is often 
 used which would not lessen the solubility. The average yellow cement, 
 however, is not made this color this way, which makes it generally 
 safer to choose the yellow cements where this color is not objectionable 
 and the maximum insolubility is desirable. 
 
 Furthermore, cements which have a given solubility when tested by 
 the manufacturer may show a different solubility test when tested by 
 someone else if the instructions of the maker have not been followed 
 closely. In fact, such influences as temperature and humidity which 
 are usually neglected by those inexperienced in testing these products 
 are likely to mislead the novice. Fully as important as these, however, 
 is the consistency of the mix. If the manufacturer of one of these pro- 
 ducts has after long experimentation so balanced his product that there 
 is a minimum of solubility, it is likely that another consistency of the 
 mass than the one used by the manufacturer will show another rate of 
 solubility. With some cements this is known to be the case. With all 
 others it is probable. A hardened mass of cement mixed to such a con- 
 sistency that it may be handled with the fingers without sticking to 
 them contains many granules of zinc oxid which have been attacked 
 only slightl}^, if at all, by the liquid. As a rule such a mass possesses 
 not only quite a different solubility than a hardened mass which was 
 mixed so that it would drop easily from the spatula, but also different 
 strength, volume change, adhesion, etc. Solubility, therefore, is 
 dependent, to some extent, upon the consistency of the mass. (See 
 Mixing Cements.) 
 
 From these data it does not seem possible to establish a standard by 
 which the solubility of cements can be determined in advance of 
 clinical use for the reason that there are too many variables. Labora- 
 tory tests furnish excellent guides to what may be expected in prac- 
 tice if conducted under fixed conditions, but if they are not conducted 
 under fixed conditions they are often worthless. 
 
 Volume Changes. — ^The better cements are tested for volumetric 
 change at the time of making the mix and during the setting. On 
 account of the energetic action between the ordinary cement liquid 
 and powder it is very difficult to learn the first movement that takes 
 place during the initial stages of setting. With some of these products 
 the first movement will have nearly all taken place before a contact 
 can be made to determine the amount of it. 
 
 It is the aim of the manufacturer of these products to have them as 
 free from volume change as possible. If the directions that the better 
 manufacturers place upon the packages are followed the volume change 
 that occurs subsequent to insertion will not be detrimental to the 
 products. If, however, no attention is given to them there may be a 
 
CEMENTS 399 
 
 marked change in volume, thereby making operations in which cements 
 are used of less value than they would otherwise be. For example a 
 cement which will shrink markedly when kept perfectly dry may 
 expand very much if subjected to a water-bath during the early stages 
 of setting. Likewise a cement which is accompanied by a certain 
 movement when mixed thin may give a different one when mixed to a 
 thicker consistence. 
 
 In much the same manner a cement which is mixed rapidly and for 
 a long time may have a different movement if hastily mixed for a short 
 time. In the one instance there is more nearly a combining weight 
 of powder for each combining weight of liquid, while with the other 
 there are likely to be many more combining weights of powder than 
 of liquid or many granules of zinc oxid not acted upon by the liquid 
 on account of insufficient mixing. Like the question of solubility, 
 no standards have been established, and it is therefore not possible 
 to give the same amount of data concerning this phenomenon as is 
 possible with amalgams. 
 
 Strength. — ^What has been said regarding the variables connected 
 with solubility and volume change in a general way applies to the 
 strength of cements. Almost any strength may be obtained from 150 
 kg. to 700 kg. on a cylinder 1 cm. in diameter, depending upon the 
 kind of cement, the manner of mixing, humidity of the atmosphere 
 in which it sets, etc. 
 
 Some cements show a retrogression in strength if tested dry and 
 after having been subjected to saliva or water. This is an indication 
 of the destructive influence of the saliva and water, and is also some- 
 what of an index of the solubility of the cement. 
 
 Hydraulicity. — Hydraulicity is a term comparatively recently applied 
 to dental cements which set promptly in the presence of consid- 
 erable moisture in the atmosphere or even in the presence of water. 
 This property seems to accompany the cements so manufactured 
 that they are rapid setting. With a given manufacturer's cements 
 it will be found that the rate of setting is controlled by the dentist 
 by furnishing different grades of liquid. These are often marked 
 "A," "B," "C," etc. Sometimes they sire marked rapid setting, 
 medium setting, slow setting, etc. It will generally be observed that 
 hydraulicity disappears somewhat as the slower setting liquids are 
 used. Since the rate of setting is controlled to a large extent by the 
 amount of water in the liquid and powder, hydraulicity may be changed 
 by exposure of either liquid or powder to the atmosphere. As a general 
 rule the silicate cements are more sensitive to alteration than the zinc 
 oxyphosphates. What generally happens when cement liquids are 
 exposed is loss of water, and as a result the cement is slower setting and 
 
400 PROPERTIES OF FILLING MATERIALS 
 
 less hydraulic; and when cement powders are exposed to a humid 
 atmosphere the result is absorption of water and more rapid setting. 
 It should be remembered, however, that the formula of the cement 
 and the method of manufacture are factors which influence these 
 phenomena. 
 
 Adhesion. — ^The property of adhesion is one that is usually developed 
 to the highest degree in the zinc oxyphosphates. Like most other 
 properties of cements it is influenced by mixing, humidity, consistency, 
 etc. Adhesion gradually appears as the powder portion is added to the 
 liquid portion up to a certain consistency for each cement and gradually 
 disappears as a putty-like consistency is reached. For the retention 
 of inlays, bands or crowns which are likely to be subjected to con- 
 siderable stress it is desirable to have adhesion developed to the highest 
 degree. It should be the aim of the dentist, therefore, to learn the 
 consistency which results in the greatest adhesion. 
 
 Mixing Oxyphosphate Cement. — It is usually advisable to have 
 everything in readiness before the powder and liquid are exposed to 
 the air, for, as has been pointed out, both are likely to have marked - 
 changes produced in them by alteration of the water content. When 
 the powder and liquid are placed upon the glass slab they should be 
 mixed at once and inserted. The amount of cement to be mixed may 
 be determined by placing upon one end of the slab, one, two, three 
 or more drops of the liquid. On the other end may be placed a sufficient 
 amount of powder to make either a thin mix or a thick one as the case 
 demands. The powder should be divided into from six to eight portions 
 before beginning the mix. One of the portions should be drawn into 
 the full amount of liquid and thoroughly spatulated, after which 
 another should be drawn in. This should be repeated until the con- 
 sistency required for a given operation is obtained. For the cemen- 
 tation of an inlay a consistency that will permit the cement to drop 
 slowly from the spatula is most suitable. For a cement filling a con- 
 sistency that is thick enough to enable the operator to handle it withv 
 but little adherence to instruments is usually best. If a large mass of 
 powder be suddently incorporated with the liquid and stirred the result 
 will be the generation of excessive heat, and as a result of the heat the 
 cement will set very rapidly. If, on the other hand, the powder be 
 added slowly and each portion thoroughly spatulated the heat gener- 
 ated will be conducted away by the slab. There is a marked difference 
 in the properties of a cement which has a given consistency reached by 
 adding rapidly a little powder thus causing the cement to set rapidly, 
 and one which has a similar consistency reached by adding much more 
 powder more slowly. The latter with more powder will possess many 
 more desirable properties than the former. The aim of the dentist should 
 
GUTTA-PERCHA 401 
 
 be to incorporate with the Hqiiid all the powder possible and maintain 
 the consistency which the operation demands. This is overlooked by 
 many dentists and their failures from the use of cements may in many 
 cases be traced to the use of a cement which had a consistency reached 
 by rapid setting instead of one which had a consistency reached 
 by the incorporation of more powder. A mass of cement which has 
 reached a certain consistency by the addition of plenty of powder will 
 set very quickly when it comes in contact with a warm tooth, but when 
 set is a much better cement from every other standpoint. 
 
 Cements should be mixed upon a large glass slab that will remain 
 cool during the mix, and should be spatulated with a large spatula 
 that will hold a large amount of the cement mass under the spatula. 
 Otherwise the spatulation is little more than a stirring process which 
 does not combine the powder and liquid as well as thorough spatulation. 
 The temperature of the glass slab should never be above that of normal 
 room temperature, and usually it is much better to cool the slab to 
 about 16° C. The mass should be spread well over the slab so that the 
 temperature will not rise much above that of the slab. There is no 
 occasion to hurry, for from one and one-half to two and one-half 
 minutes may be devoted to spatulation and incorporation of the powder 
 and liquid. German silver or platinum or gold spatulas are preferable 
 for mixing the oxyphosphates and agate spatulas or some other spatulas 
 which are highly non-corrosive and non-abrasive should be used for 
 the silicate cements. 
 
 The technic for mixing the silicate cements varies somewhat with 
 the different manufacturers' products, making it inadvisable to outline 
 a technic for mixing them. It is much more likely to yield good results 
 if the user of these products follows carefully the instructions of each 
 manufacturer as they are issued from time to time as these cements 
 are developed. 
 
 GUTTA-PERCHA. 
 
 The gutta-percha of commerce is the concrete juice of the Ison- 
 andra gutta, an evergreen tree of the order of Sapotacese, found chiefly 
 in the Malay peninsula and archipelago. The juice is secured by 
 tapping the cambium layer of the tree and catching the juice as it 
 exudes. The juice thus obtained undergoes many processes for puri- 
 fication before it is formed into sheets as seen in commerce (see works 
 on gutta-percha) and several more before it appears in the market for 
 dental purposes. 
 
 "The purified gutta-percha probably consists of a hydrocarbon 
 (pure gutta), having the formula CioHie; albane, C40H64O3; and a 
 variable compound named guttane. Pure gutta-percha possesses all 
 26 
 
402 PROPERTIES OF FILLING MATERIALS 
 
 the good qualities of gutta-percha in a much enhanced degree, becoming 
 soft and plastic on heating and hard and tenacious on cooling, without 
 being in the least brittle. The resins seem to be simply accessory com- 
 ponents which have a decidedly detrimental effect when they pre- 
 ponderate. Water, wood fibers, bark, sand, etc., occur as mechanical 
 impurities of gutta-percha." (Obach.) 
 
 It will be seen that gutta-percha resembles rubber in composition, 
 since it consists chiefly of a hydrocarbid, in which the two elements, 
 carbon and hydrogen, are present in similar proportions. Gutta- 
 percha resembles rubber also in its origin, both coming from the milky 
 juice of certain trees, although some claim a superior quality of gutta 
 is obtained by processes of extraction from the dried leaves and buds. 
 Apart from these similarities the two substances are not so very 
 similar. Rubber is a very elastic body, i. e., it is capable of returning 
 to its original form when a mechanical force causes it to undergo a 
 change. Gutta-percha, on the other hand, has a tendency to preserve 
 the change in form produced on it by the action of similar forces. 
 Rubber containing no sulphur softens under heat, as does gutta-percha,- 
 but preserves its elasticity if the heat be kept within certain limits; 
 beyond a definite degree of heat its physical and chemical properties 
 are altered. Gutta-percha, on the contrary, under heat which does not 
 exceed 110° C, is very plastic and malleable and on cooling preserves 
 the appearance and shapes which have been given to it while in the 
 plastic state. Several other differences between the two exist, such as 
 the action of light, moisture, and air, the action of sulphur on the two, 
 their non-conducting properties, etc., though the principal difference 
 in this connection is their elasticity. 
 
 Because gutta-percha preserved the shape given to it exceedingly well 
 for a material of its nature, it was introduced as a filling material into 
 dental practice, according to Dr. Kirk, about the year 1847. Since 
 that time several secret preparations have been introduced, all of which 
 have probably been gutta-percha to which other substances have 
 been added for the purpose of changing the physical properties by 
 improving the desirable ones and masking or destroying the undesirable 
 ones. One of the first to appear was by Dr. Hill, which received his 
 name. Several analyses of Hill's stopping have been given, all of 
 which are probably untrustworthy. Dr. Herman Prinz,^ however, 
 gives the formula of Hill's stopping as: feldspar, 1 part; quartz, 1 
 part; quicklime, 2 parts; gutta-percha base-plate, a sufficient quantity 
 to make a stiff mass. 
 
 Dr. Prinz does not give his authority for this formula, although it 
 
 1 Dental Formulary. 
 
GUTTA-PERCHA 403 
 
 would seem that if both feldspar and quartz were added it would be done 
 empirically. Dr. Kirk has said: "It subserved 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." Undoubtedly the present gutta-perchas and their modi- 
 fications have gradually developed from this preparation in the same 
 manner that other filling materials have become very complex com- 
 pounds as a result of years of study. The gutta-perchas for dental use 
 are divided into three classes according to the temperature of softening: 
 "Low heat," softening below 200° F.; "medium heat," becoming 
 plastic at 200° to 212° F.; "high heat," 210° to 220° F. The three 
 kinds are often numbered to distinguish them from each other, one 
 manufacturer assigning No. 6^ to the low heat, No. 7| to the medium 
 heat and No. 8^ to the high heat gutta-percha. According to Kirk 
 the low heat gutta-percha contains about 1 part by weight of gutta- 
 percha to 4 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. 
 
 In some of the products materials other than zinc oxid are used to 
 mix with the gutta-percha. The proportions, however, remain about 
 the same. Calcium carbonate, some of the sulphates, silica and other 
 oxids are among the substances claimed to be substituted for the zinc 
 oxid. 
 
 Physical Properties. — Gutta-percha in the pure state is almost 
 colorless, the small amount of coloration varying from rose to grayish 
 white. It is inodorous and insipid. It is naturally cellular in structure 
 but if drawn out its texture becomes fibrous and more resistant length- 
 wise and less transversely. It will not break until a load of about 
 25 kg. per square millimeter has been applied to it. It is but slightly 
 elastic. It is a very good non-conductor of both heat and electricity. 
 It contracts in hardening, i. e., cooling. Its density varies from slightly 
 under that of water to slightly over it, depending upon the compression 
 given to it in forming it into sheets. To the vital tissues it is very 
 bland. Gutta-percha which has been in the mouth for some time often 
 becomes harder, and its surface porosity is increased. Kirk states in 
 regard to these changes: "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 sulphid; the 
 gutta-percha apparently undergoes a species of vulcanization. It 
 becomes somewhat porous in those situations where the formation of 
 a solvent is active (lactic acid), which abstracts the soluble zinc oxid 
 from the mass. The pink variety containing the insoluble mercury 
 sulphid does not become porous but wears with a comparatively 
 
404 PROPERTIES OF FILLING MATERIALS 
 
 smooth surface when subjected to attrition." This would seem to 
 explain some of the changes very satisfactorily, but there are some 
 where other explanations would seem to apply. For example, gutta- 
 percha which has been exposed to air and light becomes friable like 
 resin and its solubility in certain reagents is increased. If, however, 
 the gutta-percha be submerged in water no perceptible change is 
 produced. Oxygen aided by light is supposed to be the factor of prime 
 importance in this change, and as a result the process is generally 
 spoken of as oxidation, although some refer to it as resinification, since 
 the extent of the change depends largely upon the resin present in the 
 gutta-percha. Thus it would seem that oxygen produces a condition 
 in gutta-percha quite analogous to the one observed by Kirk, which 
 he has attributed to the action of sulphids. In both cases, however, 
 whether the gutta-percha be in the mouth or out of it, the change is 
 apparently what he has called "a species of vulcanization." What 
 Kirk states regarding the porosity of the surface is probably true. It 
 would seem, however, since the solubility of gutta-percha in alkalies 
 increases with oxidation, that there was a chance for the surface to 
 become porous in the absence of lactic acid. Gutta-percha in the 
 normal condition is insoluble in dilute acids and concentrated alkalin 
 solutions. It is soluble in carbon bisulphid, chloroform, coal-tar oils, 
 benzol,boiling ether and oil of turpentine. 
 
 Indications for Employment. — Gutta-percha in its white and pink 
 forms, and in the three classes, low, medium and high heat, is used 
 as a temporary filling material for both the temporary and permanent 
 teeth. Its non-conductivity makes it a good material to place near the 
 pulp. Conditions are met in which the use of gold, amalgam, zinc 
 oxyphosphates, and silicate cements alone is contra-indicated because 
 of the close proximity to the pulp. In such cases a thin layer of gutta- 
 percha may be placed over the pulp, after which the permanent filling 
 materials may be inserted without serious injury to the pulp from 
 thermal changes. It has been quite a common practice to fill deep 
 undercuts with gutta-percha and cover it with amalgam or cement, or 
 cement and gold, but recent requirements for better cavity formation 
 seem to have created a demand for a harder material, and as a result 
 the zinc oxyphosphates have been more widely used. 
 
 Gutta-percha is generally used to fill the pulp chambers of devitalized 
 teeth, but even here it is, as a rule, conceded better practice to confine it 
 to the root portion of the pulp cavity and to fill any remaining portions 
 which require a similar plastic material with one of the best zinc oxy- 
 phosphates. It has been used extensively for cervical cavities in molars 
 and bicuspids which do not extend to the masticating surfaces, but the 
 demand for better oral hygiene is such that this practice has become 
 
GUTTA-PERCHA 405 
 
 less common except for relatively temporary operations. It has been 
 used for all classes of cavities in the temporary teeth, and often seems 
 to be practically the only available material which will meet the requne- 
 ments of these cases. There is a tendency, however, to use less gutta- 
 percha in the temporary teeth because of the demands of orthodontists 
 for the retention of normal contact when restoring proximate portions 
 of these teeth. There is likewise a tendency to use it less in other 
 locations in the deciduous teeth for the reasons previously given in 
 regard to better oral hygiene. 
 
 To the casual observer it might seem from this that there was little 
 use to which gutta-percha might be put. Such, however, is not the 
 case. Instead there are a great many places where gutta-percha seems 
 to satisfy more of the requirements than any other material. There are 
 places, however, where its insertion represents almost anything but 
 cleanliness. Many have a misconception regarding the impermeability 
 of gutta-percha, and as a result are reluctant to substitute other 
 materials when it can as well be done. 
 
 Dr. Black^ says: "The trial that has been made of gutta-percha 
 for the exclusion of moisture for long periods of time from ocean cables 
 has shown its absolute impermeability." That gutta-percha, used as 
 a cover for ocean cables, is almost impervious, is conceded, but it is 
 to be regretted that this statement was not qualified somewhat, 
 because as it stands the average person would take it that gutta-percha 
 was likewise impervious in the mouth. 
 
 Attention has already been called to the fact that gutta-percha did 
 not combine perceptibly with the oxygen of water, but that it did with 
 the oxygen of the air in the presence of light. Under the latter con- 
 ditions gutta-percha undergoes rapid decay and gives off an acrid 
 odor. Kirk has called attention to the action of sulphids upon gutta- 
 percha. Thus while gutta-percha is impervious when inserted it under- 
 goes decay from at least two causes. Of course, it will remain in the 
 mouth for a considerable length of time before the decay becomes very 
 perceptible, but fillings of long standing will show considerable change. 
 
 Gutta-percha is still a very useful material, but it should not be 
 allowed to remain exposed to the oral fluids for any great length of 
 time. It may be used to set almost all kinds of crowns on roots which 
 have been prepared for their reception, but should be allowed to remain 
 for a comparatively short time only. Often an operation may be nearly 
 complete, but the operator may wish to do something more before a 
 crown is placed permanently. In such cases a little gutta-percha which 
 has been made plastic by heat may serve to retain a crown. 
 
 1 Operative Dentistry, vol. ii. 
 
406 PROPERTIES OF FILLING MATERIALS 
 
 The same is true regarding its use for fillings. In an extensive 
 inlay practice gutta-percha is almost indispensable as a temporary 
 stopping from the time the cavity is prepared until the inlay is ready 
 to be set. It is usually best not to allow much time to elapse between 
 the preparation of the cavity and the setting of the inlay, but in an 
 extensive practice occasions continually arise in which this is necessary. 
 Gutta-percha may be used for sealing in treatments in the teeth when 
 the cavity is sufficiently large to permit of its adaptation without com- 
 pression of the pulp, or where the stress of mastication will not dislodge 
 it. Dr. Black^ states that "It should be the only material used for 
 sealing in dressing and for the temporary stoppings in connection with 
 treatments." As he says, gutta-percha is a trying material to handle 
 until the technic of its manipulation has been mastered, but it is diffi- 
 cult to understand why he should declare that it is the only material 
 which should be used for sealing in dressings, etc., when it is generally 
 conceded that the zinc oxyphosphates fulfil many requirements better 
 than gutta-percha. For example, suppose an accidental exposure is 
 made in the preparation of a cavity of a young patient in whom the. 
 pulp is near the surface, or suppose that the exposure has been made by 
 caries and the pulp is in a highly inflamed condition. In either case 
 the medicinal agent would probably be mixed with one of the nicely 
 prepared oxids as a carrying agent and placed gently over the exposure. 
 As a sealing for the cavity, shallow as most are, nothing would seem 
 to meet the requirements as well as one of the adhesive zinc oxy- 
 phosphates, which could be applied without perceptible pressure. 
 There are many cavities which present a different problem. They may 
 be deep and easy of access. In such cases gutta-percha would be 
 preferable to any other material. 
 
 One of the first considerations is that the surfaces to which gutta- 
 percha is applied should be dry and free from greasy materials. This 
 may be accomplished by the adjustment of the rubber dam or by the 
 use of rolls and the aid of an assistant, according to the case treated. 
 If the gutta-percha is to be inserted into a cavity the walls should be 
 parallel or even have slight retaining points, although in most cases 
 the cavity formation may be varied somewhat from that for gold or 
 amalgam. 
 
 When the cavity has been prepared for the filling it is often found 
 advantageous to moisten the walls with eucalyptol or cajuput oil. 
 This will soften the gutta-percha somewhat and add to its adhesive- 
 ness. The gutta-percha should then be made plastic by passing it over 
 the flame or by placing it upon one of the specially designed heaters. 
 It is often convenient to use the different varieties of gold annealers 
 
 1 Operative Dentistry, vol. ii. 
 
GUTTA-PERCHA 
 
 407 
 
 r^ 
 
 Fig. 355. — Flagg's gutta-percha softener and tool heater. 
 
408 PROPERTIES OF FILLING MATERIALS 
 
 for this purpose. The heater most commonly used is made of steatite, 
 and is shown in Fig. 354. The heat-retaining properties of soapstone, 
 together with its desirable surface, make it as good a heater as any 
 
 Fig. 356. — Trimmer for gutta-percha heated by electricity. 
 
 that have been designed. After the gutta-percha has been softened 
 it may be rolled into a single piece of a shape convenient for insertion, 
 and packed in place with cool instruments. It may also be inserted 
 gradually by adding piece after piece to the walls of the cavity and the 
 
GUTTA-PERCHA 
 
 409 
 
 already inserted gutta-percha. This method is usually better if there 
 is not easy access or if there is danger of compressing the pulp or forcing 
 medicinal agents through the apical foramen in devitalized teeth. 
 After the cavity is filled it should be trimmed to shape with the ordinary 
 plastic instruments by warming them to a point where they will cut 
 through the gutta-percha without tending to draw it from the cavity. 
 The instruments should be heated gently in the flame or in one of the 
 heaters, as shown in Fig. 355. Several instruments which are heated 
 by the electric current have been designed for trimming gutta-percha 
 (Fig. 356). They are very useful for some operations, but, as a general 
 rule, a little more clumsy than the regular plastic instruments. 
 
 Fig. 357 
 
 For finishing some gutta-percha fillings where it is not necessary to 
 direct the blast of hot air against the soft tissues the hot air syringe 
 is useful. It may be used in heating crowns which have been set 
 temporarily with gutta-percha. With this instrument a blast of hot 
 air may be directed against a porcelain crown, having a metal post, 
 until it can be removed easily. When the hot-air syringe is used to 
 soften the gutta-percha only very sharp instruments should be used 
 to trim off the excess, or the mass will be moved in the cavity. In 
 general, gutta-percha should not be warmed after being inserted into 
 the cavity, but should be chilled and trimmed with warm, sharp instru- 
 ments. Gutta-percha may be trimmed into shape with the ordinary 
 plastic instruments by warming them. It is better, however, to use 
 more of the sharp-edged instruments, such as carvers and excavators. 
 Heat may also be conveyed to large masses of gutta-percha, especially 
 in removing crowns set with this material, by heating a larger burnisher 
 and placing it upon the mass of gutta-percha. It is still better to place 
 a good-sized piece of copper upon an instrument handle (Fig. 357). 
 
 For the use of gutta-percha as a root canal filling see Chapter IX. 
 
410 PROPERTIES OP PlLLlNO MAT§RIALS 
 
 Gutta-percha with Other Materials.— Temporary Stopping. — ^This 
 material differs from ordinary gutta-percha chiefly in its working 
 qualities. It is prepared from both white and pink gutta-percha by 
 the addition of some of the gums or waxes, together with other materials 
 such as certain sulphates, carbonates or oxids. 
 
 It is also made without the gums or waxes. It may be prepared so 
 that it exhibits considerable adhesiveness by the addition of Burgundy 
 pitch. These preparations are designed for a variety of purposes; 
 their principal use is the stopping of excavated cavities for a short 
 time. 
 
 As the name implies they are intended for work more temporary in 
 nature than that which would require gutta-percha. As a result of 
 their use for the most temporary operations many of the qualities of 
 other plastics have been given to this material by the addition of some 
 of the above-named materials. Many of these preparations remain 
 quite hard in the mouth, although some are less resistant than gutta- 
 percha, and more plastic in every way. The most conspicuous differ- 
 ences between them and gutta-percha are that they are generally 
 softened with lower heat and have little or none of the toughness and 
 stringiness so prominent in gutta-percha. Their manipulation is 
 similar to that of gutta-percha. 
 
 Gutta-percha and Gum Shellac. — Gutta-percha may be mixed with 
 gum shellac to make a stiff and yet tough material, for use largely as 
 a base-plate. It may be used, however, for a variety of purposes where 
 other forms of gutta-percha would scarcely be rigid enough. 
 
 Gutta-percha with Medicinal Agents.^ — Such substances as oxid of 
 copper, finely divided tin, silver nitrate, eucalyptol, creosote, etc., are 
 often incorporated with gutta-percha. It is claimed by the makers 
 of some of the gutta-percha points supplied for filling root canals that 
 the process of refining the crude gutta-percha removes a natural oil 
 which should be supplied before the points are suitable for use. The 
 addition of some of the oils in such cases not only supplies what it is 
 asserted to have been removed, but for a time makes the points more 
 or less antiseptic. 
 
 The other substances mentioned are less frequently added to gutta- 
 percha. The salts of copper and finely divided tin may be advan- 
 tageously incorporated when it seems imperative to leave gutta- 
 percha in the mouth exposed to the saliva for some time. The use of 
 gutta-percha with either of these materials is hmited to remote parts 
 of the mouth on account of their color. The manipulation of these 
 mixtures is similar to that of gutta-percha alone. When these two 
 materials, or other similar substances, are combined with gutta- 
 percha, the resulting product is not unlike it, but some of the properties 
 of the combined substance are added. 
 
CHAPTER VIII. 
 
 THERAPEUTIC PROCEDURES IN THE TREATMENT OF 
 INFECTED ROOT CANALS. 
 
 By HERMANN PRINZ, A.M., M.D., D.D.S. 
 
 A MOST serious question that confronts the dental profession today — 
 and for that matter has confronted it in the past — is that which is 
 involved in establishing absolute sterility of an infected root canal. 
 The disposal of this problem in a truly scientific manner necessitates 
 the determination of the established sterility by bacteriologic tests 
 in each individual case. While the author realizes that the carrying 
 out of such procedures in the average dental qpice of today will meet 
 with numerous difficulties, due to the fact that the older members of 
 our profession have not had sufficient training in these directions, 
 nevertheless there exists no good reason why it should not be done by 
 the recent graduate who has received adequate instructions in labora- 
 tory technic. The time is not far distant when the public will demand 
 a laboratory diagnosis of serious root-canal infections for the same 
 reason that a bacteriologic examination of a diphtheritic throat is 
 demanded at present. Since the sequences of imperfect root-canal 
 sterilization in the form of focal infections resulting in metastatic dis- 
 turbances of distant organs are of common occurrence, it must follow 
 that our present methods of establishing perfect sterility of an infected 
 root canal are inadequate. 
 
 From a logical deduction based upon the much discussed problem of 
 infected root canals, it is evident that its treatment resolves itself 
 into three definite procedures: the mechanical, the chemical and the 
 therapeutic. Mechanical manipulations are intended to dispose of the 
 debris of the dead pulp, chemical procedures are primarily applied for 
 the purpose of facilitating the removal of obstructions, and therapeutic 
 applications are utilized to overcome septic conditions. 
 
 Chemical Procedures. — For the chemical disintegration "of the pulp 
 detritus, but primarily for the purpose of assisting in the opening of 
 obliterated root canals, two specific methods are in vogue, viz., the 
 alkali method, as introduced by Schreier in 1892, and the acid method, 
 as advocated by the late Callahan in 1893. Schreier's alkali method 
 intends to destroy the organic substances by means of the freshly 
 formed hydroxids of potassium and sodium derived from an alloy of 
 
 (411) 
 
412 TREATMENT OF INFECTED ROOT CANALS 
 
 potassium and sodium in the presence of water. Thereby the remain- 
 ing inorganic debris is rendered more friable and offers less resistance 
 to the advancing broach or reamer. Callahan's sulphuric acid treat- 
 ment produces the opposite effect, i. e., it destroys the inorganic sub- 
 stances by dissolution and carbonizes the remaining organic material. 
 Both methods have their advocates, and as they virtually accomplish 
 the same purpose, it is difficult to recommend one method as being 
 superior to the other. The preference in selecting one specific method 
 is largely a matter of personality. However, a most important physical 
 property possessed by the alloy and not possessed by the acid should 
 be mentioned which places the alkali treatment somewhat at an advan- 
 tage over the acid treatment. This property manifests itself as a 
 pronounced capillary affinity of the freshly formed hydroxids for mois- 
 ture, and, consequently, the caustic alkali solution penetrates into 
 those minute apertures of the root canal which a broach cannot reach 
 and in which the acid will not flow. The author has observed that the 
 opening of completely obliterated canals is often materially facilitated 
 by alternating the alkali and acid methods. Both methods incidentally, 
 destroy the offensive odor of putrescence which is always very pro- 
 nounced in a closed root canal and less so in an open canal. However, 
 it should be clearly understood that the complete absence of foul odors 
 is by no means an indication of sterility. 
 
 Dental potassium sodium (kalium-natrium) usually consists of one 
 part of metallic potassium and two parts of metallic sodium melted 
 together beneath kerosene. It is of a pasty consistency and resembles 
 mercury in appearance. The alloy is supplied in small glass tubes 
 sealed with wax or paraffin to protect it from moisture. In using this 
 alloy a barbed tantalum or an iridio-platinum broach is thrust through 
 the paraffin stopper or directly into the broken-off upper end of the 
 tube. Steel broaches are not to be recommended for this work; the 
 alloy disintegrates the metal, and, as a consequence, the broaches 
 frequently break in the canal. The very small quantity of the paste 
 adhering to the broach is worked into the pulp debris. At once a 
 chemical decomposition of the contents of the root canal takes place, 
 manifesting itself by heat and a hissing sound, with the escape of gas. 
 Potassium-sodium alloy in the presence of water is changed at once 
 into its respective hydroxids with the liberation of hydrogen. The 
 hydroxids dissolve in the remaining water and form a more or less 
 concentrated caustic alkaline solution. The putrescent pulp contains 
 water, fat, fatty acids, gases and the debris of decomposed protein 
 material. The rationale of the action of the potassium-sodium alloy 
 on the putrescent pulp debris present in a root canal may be summar- 
 ized as follows: fat and fatty acids are changed to soluble soaps. 
 
CHEMICAL PROCEDURES 413 
 
 The protein substances are rendered soluble by the caustic hydroxid 
 solution and the liberated hydrogen forces the undissolved debris to 
 the surface of the canal. The calcareous deposits in the lumen and 
 upon the walls of the canals lose their crystalline structure and become 
 friable and thereby offer less resistance to the advancing broach. The 
 offensive odor of putrescence is almost instantly destroyed. Copious 
 washing with water will remove the saponified contents of the canal, 
 and, on drying, its clean ivory-white walls are visible. The substitution 
 of the hydroxids of potassium and sodium for the metallic alloy is not 
 to be recommended; their application is difficult and their physical 
 nature does not lend itself to this procedure as readily as the alloy 
 from which the above hydroxids are obtained in statu nacendi during 
 their application. The tube containing the alloy must be hermetically 
 sealed directly after using to prevent the decomposition of the latter 
 by moisture absorbed from the air. If the sealing is not carried out 
 in a proper manner the operator will find that the contents of the tube 
 will change to a hard, crystalline mass, namely, the hydroxids of the 
 two metals. 
 
 The sulphuric acid method for opening obstruction root canals has 
 found many admirers among the practitioners, and it is probably more 
 widely employed at present than any other chemical procedure. 
 Other acids, such as hydrochloric, nitric, nitro -hydrochloric and 
 phenol-sulfonic have been advocated for this purpose during the last 
 twenty-five years. The strength of these various acids as used for 
 this specific purpose should be carefully noted as it varies greatl3\ 
 Sulphuric acid is usually employed in approximately a 50 per cent, 
 solution, hydrochloric acid in a 10 per cent, solution, nitro-hydrochloric 
 acid either pure or in a 50 per cent, solution, while phenol-sulfonic 
 acid is used in its pure form only. The therapeutic absurdity of the 
 last compound has been dealt with by the author on a former occasion, 
 and consequently it is omitted in the present discussion. 
 
 Nitro-hydrochloric acid (aqua regia) as introduced by G. W. Weld 
 in 1897 is the most efficient acid for the above purposes. It should 
 be preserved in glass-stoppered bottles and kept outside of the operating 
 room, as its fumes are most destructive to metallic instruments. A 
 50 per cent, solution of this acid may be prepared as follows: 
 
 Nitric acid 1 dram ( 4 c.c.) 
 
 Hydrochloric acid 4 drams (16 c.c.) 
 
 Water 5 drams (20 c.c.) 
 
 It may be applied upon a steel broach. Concentrated aqua regia 
 has practically very little eftect on steel, as the broach is at once 
 covered by a protective oxid by the action of the evolved nitrosyl 
 chlorid, which checks the further action of the acid upon the metal. 
 
414 TREATMENT OF INFECTED ROOT CANALS 
 
 Whatever acid is employed it should be neutralized by sodium 
 dioxid, as recommended by Kirk in 1893, and not by sodium bicar- 
 bonate, which is practically of very little value for this specific purpose. 
 The sodium dioxid is carried into the root-canal by means of a broach 
 previously dipped into chloroform; the latter liquid merely acts as an 
 indifferent conveyer of the sodium dioxid to the root canal, which if 
 water or ordinary alcohol were used readily decomposes. The chemical 
 interchange between the various acids may be portrayed by their 
 respective reactions as follows: 
 
 H2SO4 + Na202 = NaaSOi + H2O2. 
 
 or2HCL + Na202 = 2NaCl + H2O2. 
 
 or 2HNO3 + Na202 = 2NaN03 + H2O2 and 
 
 2HCL + Na202 = 2NaCl + H2O2. 
 
 The freshly formed hydrogen dioxid of the last reaction combines 
 with the available hydrochloric acid and forms nascent chlorin: 
 
 H2O2 + 2HC1 = 2H2O + CI2. 
 
 There seems to be quite a diversity of opinion concerning the self-- 
 limiting action of these acids upon tooth structure. Fifty per cent, 
 sulphuric acid solution is self-limiting; a tooth placed in this acid will 
 be coated within a day or so on every accessible surface with freshly 
 precipitated insoluble calcium sulphate, and consequently no further 
 action occurs. A tooth placed in 10 per cent, hydrochloric acid, in 
 pure or in 50 per cent, nitro-hydrochloric acid, will be completely dis- 
 solved in two or three days; these acids form soluble calcium salts. 
 The greatest solvent power is exhibited by 50 per cent, nitro-hydto- 
 chloric acid. 
 
 From a clinical point of view it is readily understood that the small 
 quantities of either acid pumped into a root canal when used with 
 caution will do no harm, especially when neutralized by sodium 
 dioxid. It is to be understood, however, that no acid should be forced 
 through the foramen. 
 
 Therapeutic Procedures. — Soon after the inauguration of the anti- 
 septic era in surgery (in 1868 by Lister), dentistry adopted his methods 
 for the treatment of root canals in an empiric way by using phenol as 
 advocated by Witzel in 1873. Since then innumerable other drugs 
 and drug compounds have been recommended at various times for 
 this purpose, among which may be mentioned: creosote, phenol, 
 chlorophenol, lysol, cresol, creolin, beta-naphthol, salicylic acid, hydro- 
 gen dioxid, zinc chlorid, mercury bichlorid, silver nitrate, iodin solu- 
 tions, iodoform, the essential oils, thymol, eugenol, eucalyptol. Black's 
 1-2-3, sodium dioxid, formaldehyd, electro-sterilization (ionization), 
 dichloramin-T, and many others. From a clinical point of view the 
 
THERAPEUTIC PROCEDURES 415 
 
 cresol-formalin mixture, as introduced by Gysi in 1899 and widely popu- 
 larized by Buckley in 1904, has received greater approval than any 
 other medicinal compound recommended for such purposes. The true 
 criterion of the efficiency of an antiseptic is its bacteriologic test 
 upon clinical cases. The high standard of the germicidal activity of 
 formalin has been frequently established by rigorous experiments. 
 Clinical data collected in the early days of the use of the above mixture 
 pointed to most favorable results. In due time, however, it was 
 observed that while "clearing up" of an infected root canal, as far as 
 the ordinary diagnostic evidence is concerned, as applied in the 
 average dental office, i. e., absence of foul odor, occurred much more 
 rapidly by the use of this mixture than by employing any of the 
 numerous other drugs usually advocated for this purpose, nevertheless 
 secondary manifestations about the periapical tissues were of frequent 
 occurrence. These disturbances are an indication that the supposed 
 sterility of the canal was not obtained at the time of its treatment with 
 the cresol-formalin mixture or that this compound produces a predis- 
 position of the periapical tissues to future infections. To be sure, 
 dental literature is pregnant with statements such as this (referring 
 to the cresol-formalin mixture) : " This dressing should remain for at 
 least three days, by which time the remedy will have sterilized the 
 entire tubular structure of the dentin, thus establishing asepsis." 
 As no bacteriologic proof is furnished to substantiate the claim, this 
 empirical statement does not carry any scientific weight, and it is out 
 of harmony with existing facts. Asepsis of an infected root canal 
 can be temporarily established by applying mechanical and chemical 
 measures, but complete sterilization of "the entire tubular structure 
 of the dentin" in a tooth in situ is impossible with the methods at 
 present in vogue. 
 
 In regard to the application of a powerful antiseptic drug for the 
 treatment of infected root canals, one should be always mindful of the 
 following facts : 
 
 1 . The agent must be able to develop the highest degree of antiseptic 
 power without doing harm to the periapical tissue. 
 
 2. It must maintain its activity for at least twenty-four hours when 
 sealed into the root canal. 
 
 3. It must not cause pain. 
 
 4. It must not discolor the tooth structure. . 
 
 Of all the above enumerated drugs only a very few answer these 
 requirements. Without entering into a lengthy discussion of the merits 
 or demerits of these drugs, it may be stated that, in general, the 
 aromatic series, i. e., phenol, and its isomers, are caustic when applied 
 in concentrated solution. The metallic salts are strong precipitants 
 
416 TREATMENT OF INFECTED ROOT CANALS 
 
 of albumin; incidentally, some of these salts, i. e., mercury, bichlorid 
 and silver nitrate, permanently discolor the tooth structure. Iodo- 
 form, on account of its most disagreeable odor and other drawbacks, 
 cannot be recommended for the work and some of the iodin compounds 
 produce lasting stains. The essential oils do not possess sufficient 
 antiseptic power as compared with other drugs. Formaldehyd in 
 the strength in which it is usually applied for root-canal treatment will 
 always kill the soft tissues when brought in contact therewith either 
 directly or in vapor form in the same manner, as the ill-fated desensitiz- 
 ing paste by its formalin content eventually kills the pulp through any 
 thickness of sound dentin. As will be pointed out in detail later under 
 Reinfection of Root Canals, no antiseptic treatment now in vogue will 
 permanently sterilize a once infected root canal. 
 
 Of all known antiseptics, chlorin, freshly prepared, and in the pres- 
 ence of moisture and a suitable temperature, possesses the highest 
 germicidal power. In suitable concentration, especially in an oily 
 solution, it is harmless to the periapical tissues and maintains its 
 activity for about twenty-four hours when sealed into a root canal-. 
 These oily chlorin solutions will not cause pain and they do not discolor, 
 but rather "bleach" tooth structure. 
 
 Regarding the concentration of the solution of dichloramin-T for 
 the purpose of treating infected root-canals, we have found that a 5 per 
 cent, solution of the salt in chlorinated paraffin, i. e., chlorcosane, 
 answers our purpose quite satisfactorily. We have heard an opinion 
 expressed to the effect that a 5 per cent, solution is too irritating when 
 used in root-canal work. We cannot subscribe to such assertions; 
 we rather believe that the pain resulting from its application was due 
 to two causes — a spoiled solution and a faulty technic. 
 
 Solutions of dichloramin-T preserve their activity for a limited time 
 only; they usually deteriorate within two or three months, and therefore 
 it is best to prepare a convenient quantity which may be readily used 
 up within a month or so. To prepare an ounce of the solution, 25 grains 
 of dichloramin-T are placed in a dark amber-colored glass-stoppered 
 bottle, which must be absolutely clean and free from moisture. One 
 ounce of chlorcosane is added, the whole is thoroughly shaken and the 
 bottle is placed in a pan containing very hat water or upon a radiator 
 or other source of indirect heat. Within a quarter of an hour complete 
 solution usually results. Direct heat in making the solution is to be 
 avoided, as it is likely to injure the compound. The solution is 
 immediately ready for use ; filtering is not necessary. As stated above, 
 only dark amber-colored or black bottles should be employed as 
 storage vessels; blue glass does not protect the solution against the 
 actinic effects of strong light. 
 
THERAPEUTIC PROCEDURES 417 
 
 Solutions of dichloramin-T must be carefully protected against heat, 
 light, water, alcohol and most metals; in fact, most common sub- 
 stances have a strong affinity for chlorin, hence the ready decomposition 
 of this solution when brought in contact therewith. Whenever the 
 solution becomes turbid and forms a deposit of crystals in the bottom 
 of the bottle or develops a pronounced odor of hypochlorous acid it 
 should be discarded. Fresh solutions, if chilled, may temporarily 
 become cloudy or even precipitate, owing to the separation of either 
 dichloramin-T or solid paraffin. Slightly warming the solution quickly 
 restores its usefulness. 
 
 Fig. 358. — Office-preparation bottle. 
 
 For office purposes it is best to keep the dichloramin-T solution in an 
 amber-colored office-preparation bottle with a ground cap (Fig. 358). 
 A small glass rod or tube kept in the bottle readily assists in obtaining 
 the few drops necessary for each treatment, to be placed upon an 
 aseptic glass tray. Under no condition should pliers charged with 
 cotton, etc., be introduced into the preparation in the bottle, and no 
 unused portions of the solution should be returned to the stock-bottle. 
 
 Dichloramin-T shares with other chlorin compounds the property of 
 being a very active lymphagogue, i. e., the amount of wound secretion, 
 especially in the beginning of the treatment, may be considerably 
 increased. The author's attention has been frequently drawn to this 
 fact by fellow-practitioners who have tried the compound in treating 
 root canals and who complained of the increased secretions from the 
 canals, which, incidentally, influences the granulation of the wound 
 most beneficially. 
 
 The application of the antiseptic principle as utilized in wound 
 sterilization depends primarily upon three definite conditions: 
 
 1. Absolute contact of the antiseptic with the infecting organism. 
 27 
 
418 TREATMENT OF INFECTED ROOT CANALS 
 
 2. Time during which this contact is maintained. 
 
 3. Sufficient concentration of the antiseptic at the point of contact. 
 Absolute contact between the antiseptic agent and the substances to 
 
 be acted upon must be rigidly observed, as no antiseptic is known to 
 act at a distance. 
 
 Finally the permissible concentration of the antiseptic depends 
 largely upon the tolerance of the tissues with which it is brought in 
 contact, and is usually obtained from clinical observation. The con- 
 centration of the antiseptic solution determines its mass action, which 
 can be safely employed for tissue sterilization (Fig. 359). 
 
 After the root canal has been suitably prepared by mechanical and 
 chemical means, so as to present a conical shaped tube, a freshly flamed 
 wire is inserted to the very apex and bent so as to form a shoulder 
 near the pulpal wall and a roentgen picture is taken. The tooth is 
 again placed under a rubber dam, the wire is removed and the canal is 
 
 Fig. 359. — Aseptic medicament tray. 
 
 washed with sterile water and dried out. Sterile paper points assisted 
 by a few drops of acetone or absolute alcohol and warm air are service- 
 able for this purpose. Fair dryness of the canal must be insisted upon, 
 as otherwise the future treatment with dichloramin-T is materially 
 impaired. 
 
 A suitable paper point is now saturated with dichloramin-T, carried 
 to the root canal and with a pumping motion an attempt is made to 
 coat the walls of the latter, and if possible a drop is forced into the 
 periapical space. The use of the warm air blast is of material assistance 
 in getting the oily solution into the finer ramifications of the canal. 
 The warm air blast is recommended in this connection solely for its 
 mechanical effect in aiding the diffusion of the dichloramin-T through- 
 out the dentin. The natural moisture present in the tooth structure 
 will assist in the production of the nascent chlorin from the reaction of 
 the dichloramin-T with the water of the organic structure of the tooth. 
 
 A fresh point carrying a drop or two of the chlorin solution is now 
 
ELECTRO-STERILIZATION 419 
 
 slowly forced into the canal to its very end and immediately sealed 
 with a suitable retainer. As we have stated above, close contact of the 
 antiseptic solution with the walls of the root canal, and if possible with 
 the surface of the involved infected area within the periapical tissues, 
 is essential to obtain therapeutic results. The first application remains 
 undisturbed for twenty-four hours. At the return of the patient the 
 point is removed aseptically and carefully examined. 
 
 A second, a third or, on rare occasions, a fourth dichloramin-T 
 treatment is placed in the dry canal and these applications again remain 
 respectively undisturbed for twenty-four hours. The paper cone 
 removed at the last sitting must show no discoloration; it must have a 
 distinct odor of chlorin and not of hypochlorous acid and it must be 
 fairly free from absorbed exudates. If possible the treatments should 
 not be left in the canal over twenty-four hours; at the end of this time 
 the chlorin compound is completely exhausted and usually a flow of 
 lymph, as referred to above, is the sequence. Should the flow of lymph 
 be rather copious a dry, sterile paper cone may be inserted for a day or 
 two under a hermetical seal; usually normal conditions of the periapical 
 tissues will speedily return. If at the last treatment the canal is found 
 satisfactorily clean a microscopic examination in the form of a smear 
 obtained from the removed cone is made. If the examination indicates 
 sterility no time should be lost in filling the canal at once. 
 
 Regarding the existing sterility of a primarily infected root canal 
 as treated by the above-outlined dichloramin-T method, it should be 
 emphasized that rigorous bacteriologic tests were made in numerous 
 instances in the routine way by plating out scrapings by incubation 
 upon agar plates in bouillon, etc. After exposure in an incubator for 
 various lengths of time, usually from forty-eight to seventy-two hours, 
 it was observed that bacterial growth from the previously infected 
 canals was negative, i. e., no cultures were obtained usually after the 
 third, and, in a few cases, after the fourth treatment. 
 
 ELECTRO-STERILIZATION. 
 
 When a solid, a liquid or a gas enters into solution and is capable of 
 conducting an electric current, according to Arrhenius, the solution 
 undergoes certain changes which are grouped under the generic term 
 electrolysis. This latter term, with the following nomenclature, was 
 introduced by the English physicist Faraday (1791-1867) and is still 
 generally employed. The solution itself is known as the electrolyte 
 while the dissociated products are referred to as ions. The terminals 
 at which the electric current enters or leaves the electrolyte are called 
 electrodes. An ion (ion = going) ma^y be referred to as being the dis- 
 
420 TREATMENT OF INFECTED ROOT CANALS 
 
 sociated product of a chemical decomposition which is capable of con- 
 ducting an electric charge and which travels in the direction of an 
 oppositely charged pole. Those ions, which are charged negatively, 
 migrate to the anode, i. e., the positive pole, and are known as anions, 
 while the positively charged ions migrate to the negative pole, the 
 cathode and are known as cations. Relatively speaking, all metals, 
 alkaloids and hydrogen are positive ions, i. e., cations, while all acids, 
 bases, halogens, hydroxyl compounds and oxygen are negative ions, 
 i. e., anions. 
 
 As Ostwald has suggested the cation may be designated by the posi- 
 tive sign + or by • , and the anion by the negative sign — or by ' . 
 "An ion may be either a charged atom, as in the case of the silver ion, or 
 a charged group of atoms or molecules. In the case of silver nitrate 
 AgNOs the cation is Ag and the anion is the molecule or radicle NO3. 
 The charge of the NO3 ion is one negative unit and that of the Ag ion 
 is one of positive unit, as both the ions are monads or monatomic." 
 (Lewis Jones.) 
 
 A simple solution of salt in water dissociates the salt into electro^ 
 molecules, the ions, which exist independently of the action of a gal- 
 vanic current. The number of positively and negatively charged ions 
 is equimolecular, i. e., the solution is electrically neutral. The ions 
 themselves are suspended in the solution in a chaotic mixture. The 
 passing of the galvanic current, according to Nernst, by its electro- 
 motive force, causes a definite movement of the ions in an orderly 
 direction to their specific centers of attraction, ^. e., respectively to the 
 positive and the negative poles. 
 
 The degree of concentration of the solution to be ionized has no effect 
 upon the number of ions produced; the latter depends upon the strength 
 of the current multiplied by the time for which it is applied. In other 
 words, ionization is a manifestation of transformed electric energy in 
 accordance with Faraday's law. The amount of decomposition of an 
 electrolyte is proportional to the amount of electricity which flows 
 through it. 
 
 The process of electro-sterilization of infected root canals concerns 
 itself primarily with the disinfectant action of the liberated ions and 
 less so with their supposed medicinal qualities. The disinfectant action 
 is principally confined to the surface of the object treated, although a 
 certain depth of penetration is desirable. 
 
 The electric current, per se, at least in the strength suitable for root 
 sterilization, does not produce any measurable bactericidal action. A 
 weak current passed for hours through diluted sulphuric acid prior to 
 entering an inoculated Petri dish does not inhibit the growth. In 
 the presence of an electrolyte the current acts on the dissociated ions 
 
ELECTRO-STERILIZATION 
 
 421 
 
 of the latter, and, depending upon their specific chemical nature, some 
 of the most powerful disinfectants may be obtained. It is claimed 
 that certain pure metals as such possess slight antiseptic action. This 
 property was first observed by the late Professor Miller. According 
 to Behring this antiseptic action is the result of the reaction of certain 
 waste products of bacteria, primarily lactic acid, with those metals 
 which are capable of forming soluble salts and which diffuse through the 
 medium. This antiseptic action of metals must not be confounded 
 with the oligo-dynamic action of certain pure metals in their colloidal 
 
 Fig. 360. — Long-handle electrode with iridio- 
 piatiniim point. 
 
 Fig. 361. 
 
 -Insulated electrode 
 holder. 
 
 state, as copper, for instance, on low-type plant cells. Of the pure 
 metals, according to the classic experiments made by Thiele and Wolf, 
 mercury, silver and copper are the only ones which produce poisonous 
 salts in the presence of bacteria, while the other tested metals, i. e., plati- 
 num, palladium, gold, aluminum, magnesium, zinc, lead, tin and iron 
 are wholly devoid of action. In the discussion of electro-sterilization 
 of infected root canals great stress is frequently laid by certain men 
 upon the specific nature of the metallic electrode placed in the root 
 canal as being the factor which produces the desired germicidal effect. 
 
422 TREATMENT OF INFECTED ROOT CANALS 
 
 Rheim, for instance, insists on using a chemically pure zinc electrode 
 in the presence of a sodium chlorid solution, claiming that "nascent 
 zinc chlorid" is formed during the process of electrolysis. Other 
 practitioners employ a copper electrode and a weak zinc chlorid solu- 
 tion as a substitute for the sodium chlorid solution. A zinc electrode 
 employed for electro-sterilization of root canals is not onl}' devoid of 
 any germicidal action, but it is also an ill-chosen metal for this purpose, 
 because a zinc wire is too brittle to be filed fine enough to readily enter 
 a minute root canal without inviting danger of breaking (Figs. 360 and 
 361). 
 
 Ionization of a metallic electrode occurs primarily in the presence of a 
 suitable electrolyte, i.e., a solution of a salt of the metal of the respective 
 electrode. While theoretically it is true that ions of the respective 
 electrode must be produced as a secondary sequence of the primary 
 ionization of the electrolyte, practically, in employing the low amperage 
 tolerated by the human body these ions are not demonstrable with the 
 ordinary chemical reactions, consequently they cannot exercise any 
 therapeutic effect. A zinc electrode in the presence of a sodium chlorid 
 solution is not ionized in the short space of time and with the low amper- 
 age employed in the electro-sterilization of root canals, consequently 
 "nascent zinc chlorid" ions, which are believed to have been produced 
 from zinc electrodes, are imaginary therapeutic bodies. When a high 
 amperage is employed in experimental work outside of the human 
 body, sufficient hydrochloric acid is obtained as a secondary product 
 which will act on the zinc pole, forming zinc chlorid. 
 
 The Electric Current and Its Accessories. — ^The only current suitable 
 for electro-sterilization is the direct current. The alternating current 
 cannot be used unless it is changed by a transformer. This may be 
 accomplished by a chemical "rectifier" or a small motor dynamo. 
 The chemical rectifier without potential equalizer has not been found 
 satisfactory by the author. The source of the current may be obtained 
 from the main line, from an accumulator or a storage battery or from 
 a series of cells. If the street current is used it must be reduced by a 
 rheostat to about 30 to 40 volts. A number of lamps, mounted in 
 series, one lamp of sufficiently high voltage, or a wire rheostat, is 
 usually employed for this purpose. An ordinary switchboard is less 
 suitable, as there is always danger of shocking the patient through 
 imperfect control (Fig. 362). If the street current is used a knife 
 switch should be interposed between the rheostat and the current 
 controller. If cells are employed — and many practitioners and most 
 of the reliable electric supply houses regard a cell series as the safest 
 means for the purpose in view — about 18 to 24 Leclanche wet cells or 
 an equal number of ordinary dry cells (Columbia No. 6) are most 
 
ELECTRO-STERlLIZA TION 
 
 m 
 
 Useful (Fig. 363). Tlie silver chloric! cell is less serviceable for our 
 purpose. x\n ordinary wet or dry cell furnishes approximately a little 
 
 Fig. 362. — Switchboard for electro-sterilization. (Mcintosh.) 
 
 Fig. 363. — -Galvanic battery for electro-sterilization. 
 
424 
 
 TREATMENT OF INFECTED ROOT CANALS 
 
 over one and a half volts. Recently, compact types of dry-cell batteries 
 furnishing a current of very low amperage and medium voltage, 
 intended for wireless telegraphy, have been placed on the market. 
 
 Fig. 364.— The S. S. White current controller. 
 
 These cells are mounted in series and connected to binding-posts. 
 From these posts the current is conveyed by means of flexible conduct- 
 ing cords to a suitable controller (Fig. 364). The most important 
 feature of a serviceable controller consists in the gradual increase or 
 
 Fig. 365. — Weston milliamp^remeter. 
 
 decrease of the current in very small fractions of a milliampere without 
 shocking the patient. A graphite or a series wire rheostat, either 
 plain or as a shunt, is serviceable for such purposes. The markings 
 
ELECTRO-STERILIZATION 425 
 
 on the current controller, be they volts or arbitrary numbers, have little 
 bearing on the practical application of the current. 
 
 The current controller, in turn, is connected with a milliampere- 
 meter, an instrument for measuring the quantity of strength of the 
 current (Fig. 365). The milliamperemeter is the instrument of preci- 
 sion which guides the operator in his work, consequently too much 
 emphasis cannot be placed upon the importance of obtaining a perfect 
 working instrument. 
 
 At this point the author may be permitted to digress for a moment 
 from the subject proper and call to the mind of the reader the funda- 
 mental nomenclature governing electrical measurements — as far as it is 
 utilized in the following discussion. By the term ampere is meant the 
 unit of strength of a current. A milliampere is a thousandth part of 
 an ampere, expressed as MA. A volt is the measure of the unit of 
 pressure of the current, i. e., the electric power necessary to drive a 
 current of one ampere through a resistance of one ohm. It is referred 
 to as the electromotive force and expressed as E. M. F. An ohm 
 measures the resistance of a circuit through which a current flows. 
 
 From the above explanation, as related to the process of electro- 
 sterilization, it is obvious that the correct measurement of the amount 
 of current applied to a patient is of the utmost importance, as it is 
 the safest means of guiding us during its application. Hence the impor- 
 tance of procuring a trustworthy milliamperemeter. The best instru- 
 ments are those constructed after the Deprez-d'Arsonval deadbeat 
 (non-trembling) type. The Weston milliamperemeter is a most reliable 
 current gauge. The face of the latter instrument, suitable for this 
 work, should be calibrated into 5 milliamperes, with subdivisions of a 
 tenth to a twentieth of a milliampere. To convey the current to the 
 patient, different colored flexible cords are employed which terminate 
 in suitable electrodes (Fig. 366) . In connecting up the whole apparatus 
 extreme care must be observed in joining equal poles to each other, 
 namely, positive pole must be connected to positive pole, and vice 
 versa. To locate the respective poles the following simple experiment 
 may be employed. Moisten a piece of blue litmus paper with water, 
 place the two poles of the battery about one inch apart on the wet 
 paper and turn on the current. In a few moments a pink spot will 
 develop where the ■positive pole touches the paper. 
 
 The two electrodes are terminals attached for the purpose of convey- 
 ing the current to the patient, and consist of a negative electrode 
 which is to be placed on the patient's skin surface, and a positive 
 electrode to be introduced into the tooth. The negative electrode 
 may be a piece of metallic tubing held firmly in the patient's hand, or a 
 sponge electrode fastened to his wrist, or one of various modifications 
 
426 
 
 TREATMENT OF INFECTED ROOT CANALS 
 
 thereof. The size of the negative hand electrode is important; it 
 should present at least five square inches of surface area, which are to 
 be brought into contact with the patient. A large surface of the nega- 
 tive electrode reduces the resistance, and consequently the tingling 
 sensation 6v even blistering caused by the heat of a small electrode is 
 
 Fig. 366. — Metal negative hand electrode. 
 
 avoided. The author prefers the plain tube hand electrode, as it 
 avoids the cumbersome wetting with salt water, loss of time in adjusting 
 it, etc. It is immaterial in which hand the electrode is held. Rings, 
 bracelets, wrist watches, etc., must be removed, otherwise blistering 
 of the patient's skin by mere contact may occur. Placing the negative 
 
ELECTRO-STERILIZATION 427 
 
 electrode upon the patient's cheek, lip or giun surface by means of a 
 clamp or spring, as recommended by some operators, is to be avoided, 
 for the reason that severe burns may result. It has been stated that 
 this blistering results from the formation of caustic sodium hydroxid 
 near the negative pole. The blistering is the result of imperfect 
 contact between the skin and the metal electrode, thereby increasing 
 the resistance of a small area to such an extent as to produce high heat, 
 i. e., an electric burn. The positive electrode to be introduced into the 
 tooth consists of a piece of iridio-platinum wire, No. 20 gauge, about 
 one inch long and tapered to a delicate point. The iridio-platinum 
 alloy possesses the necessary flexibility, which is lacking in pure plati- 
 num. The point itself is ground blunt so as to avoid being caught 
 when introduced into tortuous canals. Various sizes of these points 
 may be kept on hand. No other metal should be employed for such 
 purposes. To substitute the iridio-platinum point by zinc, copper or 
 any other metal, with the view of aiding its therapeutic effects is not 
 only useless, but markedly interferes with the action of electrolysis in 
 the relatively sm.all area of a root canal and the resultant ions may dis- 
 color the tooth. A long-handle electrode holder, insulated with hard 
 rubber, is essential to suitably unite the electrode with the conducting 
 cord. The holders ma}' be of various types so as to give ready access 
 to all parts of the oral cavity. From the foregoing description of the 
 source of the current, its control and its mode of application, it may 
 be observed that essentially it is a duplicate of the armamentarium as 
 applied in producing cataphoresis. Any apparatus, therefore, that is or 
 has been used for inducing cataphoresis may be equally successfully 
 employed for the electro-sterilization of root canals. 
 
 Electro-sterilization Equation. — ;In the various communications treat- 
 ing on root sterilization by electrolysis the very important questions 
 concerning the time during which the current is applied, the number 
 of milliamperes employed and hacteriologic tests of the resultant 
 sterility are usually vaguely treated. When sterility of a primarily 
 infected root canal is spoken of in the present light of hacteriologic 
 knowledge the truth of this assertion has to be proved by rigorous 
 tests, otherwise the term sterility loses its significance. These tests 
 are readily made b}^ obtaining cultures at stated intervals from the 
 canal under treatment until complete negative results of growth are 
 obtained. Regarding the hacteriologic tests as applied to electro- 
 sterilization, the author proceeded as follows : cultures of the infected 
 root canal were made before treatment was instituted and then every 
 five minutes thereafter for a given period of time, usually twenty 
 minutes. The infected agar plates were incubated in the routine 
 manner. Incidentally the time of applying the current and its 
 
428 TREATMENT OF INFECTED ROOT CANALS 
 
 strength were carefully noted. By comparing the results obtained 
 a definite relationship between the strength of the current, the 
 time of application and the resultant sterility could be established. 
 Zierler deserves credit for having first noted the interrelationship of 
 these factors, and he has suggested the use of a numerical constant 
 which furnishes a working basis for its clinical application. This 
 constant is 30. By multiplying the number of milliamperes employed 
 by the time in minutes used in the process of obtaining a sterile root 
 canal, invariably a number was obtained which closely hovered about 
 the figure 30; or, reversely, by dividing the constant 30 by the number 
 of milliamperes employed a quotient is obtained which gives the time 
 in minutes during which the current must be applied. Apparently 
 a given infected surface area requires for its sterilization a specific 
 amount of migrating ions; at least this assertion can be verified, as far 
 as the germicidal action of ionized chlorin is concerned, in the steriliza- 
 tion of infected root canals. Hence the numerical constant 30 may be 
 looked upon as expressing in units the surface area of an average root 
 canal. In the author's experimental work and in clinical practice he 
 has based his observations upon the above principle and has collected 
 sufficient data as proofs that the appended electro-sterilization equation, 
 as this formula has been termed, is a reliable guide for the application of 
 these procedures in the treatment of infected root canals; 30 MA = T, 
 the 30 representing the numerical constant, MA the number of milliam- 
 peres and T the time in minutes. 
 
 Clinical Application of Electro-sterilization. — To convey to the 
 reader a practical working knowledge of the clinical application of the 
 principles of electro-sterilization it is probably best to describe the 
 actual modus operandi in detail as employed in a typical case. The 
 patient seated in the chair is covered with a rubber apron sufficiently 
 large to reach over the chair arms, so as to protect him from accidental 
 shock by "grounding" the current. The root canal of the tooth to be 
 treated must be mechanically cleansed of its debris, and if necessary 
 enlarged so as to give free access to the wire electrode. Before starting 
 the ionizing process it is best to assure one's self of the correct working 
 of the current by bringing the two poles together for a moment; the 
 moving of the needle of the milliamperemeter in the right direction 
 acts as an indicator that the apparatus is in working order. The 
 rubber dam having been adjusted the root canal is now flooded with a 
 1 per cent, saline solution — an S. S. W. minimum syringe is useful for 
 such purposes. The patient takes a firm hold of the negative electrode 
 with his hand, which must not carry rings, bracelets, etc. Before 
 introducing the freshly flamed positive pole into the canal the operator 
 should see that the knife switch is open, and that the controller is 
 
ELECTRO-STERILIZATION 429 
 
 set at zero. If the wire electrode fits the canal too loosely a few 
 fibers of cotton moistened with salt water are wrapped about it. The 
 needle is introduced as near to the apex as possible and the knife switch 
 is closed. The controller is now very slowly turned on and the patient 
 is told to at once raise his hand when he feels the slightest sensation. 
 The moving needle of the milliamperemeter will indicate to the operator 
 that the current is flowing in the right direction. When the patient 
 raises his hand the controller is turned very slightly back, left at this 
 point for about half a minute and again very slowly turned forward 
 until the patient again responds or until the point of tolerance is estab- 
 lished. This point the author has termed the "irritation point." 
 A glance at the milliamperemeter informs the operator of the number of 
 milliamperes employed. The operator now recalls to his mind the 
 numerical constant 30 and quickly calculates the time of his particular 
 case of electro-sterilization by dividing thirty by the number of milli- 
 amperes employed. The resultant quotient gives the time in minutes 
 for which the current must be applied. Example: if the patient's 
 irritation point is 2.5 MA, twelve minutes by the watch are required for 
 the sterilization of this particular root canal. If the resultant quotient 
 is a fraction the author recommends that the next higher unit be sub- 
 stituted as the indicator of the time. Each root canal of a multi- 
 rooted tooth is preferably treated separately. If a clamp electrode 
 holder is employed to clasp the two or three wires inserted into the 
 multirooted tooth care should be exercised to prevent short-circuiting. 
 To avoid polarization of the positive electrode, i. e., covering by a film 
 of nascent gases which materially interferes with the flow of the 
 current, the needle should be removed at five-minute intervals (turn 
 off current previously!) and wiped off. During the process of electro- 
 sterilization a drop of salt water should be added about every minute 
 to make up for loss by evaporation. Care must be exercised to 
 prevent short-circuiting of the current by allowing salt water to seep 
 under the rubber dam and thus transfer the current to the gum tissue. 
 After finishing the operation the controller is slowly turned to zero, the 
 knife switch is opened and the electrode removed from the tooth. 
 Never remove the electrode without having first cut off the current, 
 otherwise the patient receives a disagreeable shock or a flash of light 
 passing in the eyes. On passing a few fibers of cotton or a paper cone 
 in the root canal a pronounced odor of chlorin should be perceptible. 
 A wisp of cotton or a cone wet with salt water is placed in the root 
 canal and the latter is closed with gutta-percha stopping. The 
 treatment is to be repeated within twenty-four hours, and if necessary 
 again on the third day, and the canal is immediately filled after the 
 last treatment. A root canal should never be filled immediately after 
 the initial treatment; an interval of at least twenty-four hours should 
 
430 TREATMENT OF INFECTED ROOT CANALS 
 
 be allowed before doing so. Migrating ions do not develop their 
 maximum degree of therapeutic efficiency within the short period of 
 time during which the current is applied. It requires practically 
 twenty-four hours to produce their full activity within the region of a 
 root canal and its surroundings. The clinical indications of complete 
 sterility are definite odor of chlorin and a clean paper or cotton cone 
 after twenty-four hours' insertion. In doubtful cases sterility should 
 be verified by a bacteriologic test. If a metal filling is present in 
 the tooth under treatment it should be removed, because if touched by 
 the electrode after the current is turned on it may be short-circuited 
 through the filling and the patient will receive a shock. Moreover the 
 action of the chlorin ions upon the metals of the filling materials results 
 in the formation of metallic chlorids, which infiltrate the dentin 
 structure, producing discoloration. This is particularly true in the 
 case of gold chlorid thus formed, which by secondary decomposition 
 stains the tooth structure a deep purple tint. 
 
 When the products of pulp decomposition pass beyond the foramen 
 of a tooth, localized pathologic disturbances of the pericementum, 
 arise, which usually lead to the formation of an abscess. Without 
 entering into the further discussion of the pathology of the disturbances 
 at this moment, let us assume that the disturbances are eradicated by 
 establishing drainage along the lines of least resistance. If the drainage 
 takes place through the root canal this condition is spoken of, although 
 wrongly, as a blind abscess, while if the drainage occurs through an 
 artificially established canal through the bone and gum tissue a fistula 
 results. Acute types of the enumerated disturbances yield readily 
 to electro-sterilization, provided the salt solution and the positive 
 electrode reach the seat of the infection. For the treatment of an 
 abscess draining through the root canal the positive electrode is thrust 
 through the foramen into the abscess cavity; the treatment of an 
 abscess with a fistula requires a somewhat modified application. In 
 the latter case complete communication between the root canal and the 
 mouth of the fistula must be first established by forcing warm salt 
 water through the canal. The root canal is now treated as outlined 
 above; the fistula itself requires a separate application of the procedure. 
 The positive electrode is passed into the fistula, entering at its outlet 
 and carried along the fistulous tract until the root is felt, while the 
 negative pole, consisting of a piece of copper wire surrounded by salt 
 water, is placed in the root canal. The sterilization equation for this 
 treatment is the same as already outlined. Usually the patient requires 
 a lower milliamperage for such work. All types of chronic abscesses 
 will yield to this method of treatment, provided the necrotic area 
 involved is very small and that the seat of disturbance is reached hj the 
 pl^ctrode and by the salt watey , 
 
CHAPTER IX. 
 
 THE PREPARATION AND FILLING OF ROOT CANALS.^ 
 
 By EDGAR D. COOLIDGE, D.D.S. 
 
 Introduction. — There never has been a time when a greater or more 
 vital problem confronted the dental profession than the present one 
 in the proper handling of pulpless teeth. The one extreme practice of 
 extracting all pulpless teeth or the other extreme of retaining all teeth 
 regardless of the condition of the peridental membrane and alveolar 
 process about their roots is not the best service to mankind. There are 
 many teeth being extracted which should be properly treated and the 
 roots filled and at the same time some of the profession are failing to 
 recognize the danger to the general health of the patient in retaining 
 badly infected teeth involving the periapical tissue. The difficulties 
 encountered in the operation of pulp removal and filling root canals of 
 most teeth are weighing down upon the profession and as a result the 
 tendency to extract teeth requiring root-canal operations is becoming 
 too general. The tooth which is saved by good root-canal filling is 
 usually able to render a service to the patient unequaled by an artificial 
 substitute. It requires much patience and skill coupled with persever- 
 ance to accomplish good results in root-canal filling and the operator 
 who acquires these characteristics and takes advantage of the improved 
 equipment and the higher standards of excellence in this work will 
 doubtless have a degree of success in proportion to his effort. 
 
 EQUIPMENT FOR ROOT-CANAL OPERATIONS. 
 
 The equipment for root-canal operations may be grouped for con- 
 venience under the following headings: 
 Sterilizers. 
 Root canal instrument cabinet. 
 
 1 Credit is hereby given to those in whose minds many of the ideas herein expressed 
 originated or were developed. The continued study of the most excellent chapters on 
 root canal operations in the two books: "Operative Dentistry" and "Special Dental 
 Pathology" by Dr. G. V. Black has been the guiding light in my efforts to successfully 
 fill root-canals. Dr. Black's minute description of dental anatomy and his detailed and 
 most complete exposition of the operations on root canals have been of immeasiu-able 
 benefit to the dental profession in standardising root-canal operations and the greatest 
 tribute to his work is the fact that hupdredp of dentists are attempting to follow his 
 teaching. 
 
 (43;) 
 
432 PREPARATION AND FILLING OF ROOT CANALS 
 
 Supply bottles. 
 Containers. 
 Cotton supply. 
 Burs and broaches. 
 Pluggers. 
 Filling materials. 
 Operating tray. 
 Sterilizers. — Sterilization may be accomplished by the following 
 methods : 
 
 Boiling. Dry heat. 
 
 Steam. Disinfectant drugs. 
 
 Fig. 367. — Dry heat sterilizer. Automatic control makes it possible to maintain any 
 degree of temperature from 200° F. to 350° F. for an indefinite period. A temperature 
 of 230° F. will sterilize in ten minutes, with a higher degree of temperature less time is 
 required, and with a lower temperature the time must be lengthened proportionately. 
 Especially useful for cotton, absorbent points, gutta-percha cones, napkins, dressings, etc. 
 
 The first equipment for root-canal operations is a sterilizer that is 
 practical and efficient. For the sterilization of metal instruments 
 most any water heater in which instruments can be conveniently boiled 
 for at least twenty minutes answers the purpose for sterilizing by boiling 
 and there are many satisfactory makes available for the particular 
 needs of every office. The sterilization of dressings, cotton, towels and 
 other root-canal materials has become a necessity for the dental office 
 and it is necessary to have a suitable sterilizer for this purpose (Figs. 
 367 and 368) . Simplicity is an important item in the construction and 
 operation of a sterilizer for dressings and other materials for root canal 
 
EQUIPMENT FOR, ROOT-CANAL OPERATIONS 
 
 433 
 
 work. If the operation of the sterilizer is too burdensome or there is 
 too much time lost in sterilization there is a great temptation to neglect 
 this most important procedure. The initial cost should not be so great 
 
 Fig. 368. — Steam chest sterilizer. Moist heat may be obtained varying from 190° F. 
 to_215° F. and can be maintained for an indefinite period. It is necessary to maintain 
 this temperature at least thirty minutes and is safer to sterilize three successive days 
 before using the materials under sterilization. Especially useful for materials used in 
 root-canal operations as Fig. 367. 
 
 as to limit the use of proper equipment in any office. There are some 
 objections to boiling broaches, especially those with barbs. These 
 may be subjected to dry heat at 230° F. for ten minutes or they may be 
 
 28 
 
434 PREPARATION AND FILLING OF ROOT CANALS 
 
 immersed in a 10 per cent, solution of lysol in water (Fig. 369). For 
 barbed broaches, root files and surgical knives this form of sterilization 
 is quite satisfactory if all organic matter and debris are thoroughly 
 cleansed from the instruments before immersing them in the solution. 
 The solution should be renewed daily. While the operation is under- 
 
 FiG. 369. — ^B id die broach sterilizer. Compartments to keep broaches separate while in 
 
 lysol solution. 
 
 way, broaches should be immersed in 95 per cent, phenol followed by 
 alcohol before each insertion into the pulp chamber and canal. This 
 necessitates a suitable container for these liquid sterilizing agents 
 which is convenient and attractive. The container or medicament 
 tray (Fig. 370) should be kept before the operator constantly and used 
 for the purpose of maintaining asepsis of the broaches during the 
 
EQUIPMENT FOR ROOT-CANAL OPERATIONS 
 
 435 
 
 operation. It is quite as important to provide against contamination 
 of the instruments while operating as it is to start with sterile instru- 
 ments and this method of immersing the broach is simple and con- 
 venient and soon becomes a matter of unconscious habit. 
 
 Fig. 370. — Medicament tray. Convenient tray with compartments for phenol and 
 alcohol to sterilize broaches while operating. Other compartments for other drugs and 
 for broaches. 
 
 Root Canal Instrument Cabinet. — The equipment for root-canal 
 operations should be kept separate from the other operating instru- 
 ments. The large instrument cabinet has no satisfactory place in 
 which to keep these instruments and materials. They should all be 
 kept together as a unit in a small cabinet separated from all other 
 equipment and as an aseptic precaution should be constantly subjected 
 
 Fig. 371. — Root canal instrument cabinet. Air tight cabinet for formaldehyde 
 sterilization. Shelves being removable make convenient operating trays with complete 
 equipment for operation in place. 
 
 to formaldehyde to maintain sterilization (Fig. 371). The cabinet 
 shelves should be removable so that the entire contents of a shelf may 
 be taken out at one move to be used as an operating tray carrying the 
 entire operating unit. This shelf containing all the instruments and 
 materials makes an ideal aseptic operating tray to be placed upon the 
 bracket before the operator. 
 
436 
 
 PREPARATION AND FILLING OF ROOT CANALS 
 
 Supply Bottles. — It is quite necessary to have a stock of broaches 
 sterilized, ready for use and kept within easy reach while operating, 
 for one is often compelled to draw upon the surplus supply during 
 an operation. By placing the stock in small screw top glass bottles 
 
 Fig. 372. — Broach bottles. Screw top bottles for surplus broach supply. 
 Broaches sterilized and kept ready for use. 
 
 (Fig. 372) the operator can see at a glance when the stock is low and 
 order before the supply is exhausted, saving much inconvenience. 
 
 The drugs which are regularly used may be kept in dropping bottles 
 to save time and inconvenience. Glass dropper stoppered bottles 
 
 Fig. 373. — Glass dropping stoppered bottles. For dropping drugs upon the medicament 
 tray instead of dipping into bottles. 
 
 one-half ounce in size (Fig. 373) make very satisfactory containers for 
 daily use. The habit of dipping into bottles containing drugs should 
 be discontinued. 
 
 Chloropercha can best be kept in a small bottle with a glass cap top 
 
EQUIPMENT FOR ROOT-CANAL OPERATIONS 437 
 
 from which a small i)ortion may be remo\'t'd \vh.e]i needed for the 
 operation. 
 
 Containers. — In operating in root canals it is necessary to use many 
 small instruments of different sizes as well as several drugs. In order 
 to accommodate these various articles during the operation it is well 
 
 
 
 Fig. 374. — Glass container for gutta-percha cones. Gutta-percha cones cut in short 
 
 lengths ready for use. 
 
 to have several small glass or porcelain dishes (minim trays) for the 
 broaches, small cups for different drugs for use during the operation 
 thus to avoid dipping into the medicine bottle. A suitable dish with 
 compartments for different sizes and lengths of gutta-percha cones 
 (Fig. .374) may be obtained which accommodates these various pieces 
 without their becoming mixed, thus conserving 
 the operator's time as they should always be 
 prepared for use by the assistant in advance. 
 
 The Cotton Supply. — The cotton supply for 
 root-canal operations should include sterile cotton 
 pellets and absorbent paper points (Fig. 375). 
 There is no need for loose cotton. It is not 
 necessary to wrap cotton upon a broach since 
 the advent of the absorbent paper point. The 
 method of keeping cotton constantly before one in 
 an open jar and rolling it with the fingers should _ ak b nt 
 
 be abandoned because it is not aseptic without paper point. 
 
 sterilization after being handled. Sterilization of 
 cotton wrapped upon a broach is easily overlooked or neglected, hence it 
 is far safer to abandon the loose cotton than to attempt to sterilize it 
 after wrapping it upon the broach. When the broach is remo\ed from 
 the canal it usually carries debris or organic matter which must be 
 cleaned from it. A small square of sterile gauze or muslin, five inches 
 each way fastened to a corner of the towel covering the patient, is a 
 
438 
 
 PREPARATION AND FILLING OF ROOT CANALS 
 
 clean and convenient means with which to remove such debris and adds 
 to the neatness of the operation. A pair of small scissors is necessary 
 to cut pellets or points to satisfactory size. 
 
 Burs and Broaches. — There is a great variety of burs and broaches 
 which may be used to advantage and different operators might vary in 
 their selection. The spear drill for straight or contra angle hand-piece 
 for cutting enamel; the cylinder or fissure bur No. 59 and the large 
 
 Fig. 376. — Short handle barbed broaches. 
 
 round bur No. 7 are all that seem necessary. The Gates-Glidden burs 
 are very useful in opening the mouth of the canal to facilitate entering 
 the canal with the broach. 
 
 Broaches should be selected in graded sizes from the XXX (triple X) 
 fine to the fine in both smooth and barbed broaches. Short handled 
 broaches (Fig. 376) are superior to long ones as the sense of touch is 
 lessened in proportion to the distance from the working point. Metal 
 broach handles should be used because of convenience of sterilization 
 
 12 3 4 5 
 XIP XP F M C 
 Style B 
 
 Fig. 377. — Root canal files. 
 
 and in order to economize the operator's time it is well to have one for 
 each size of broach to be used. The handles should be marked to 
 prevent loss of time in looking for the proper size. The root canal file 
 (Fig. 377) is an indispensable instrument for enlarging canals and 
 should be used in the various graded sizes from extra fine to coarse. 
 
 Root Canal Pluggers. — The pluggers (Fig. 378) for packing the 
 gutta-percha into the canal should be slender and long with sufficient 
 
EQUIPMENT FOR ROOT-CANAL OPERATIONS 
 
 439 
 
 temper to stand considerable pressure. Untempered pluggers are of 
 little use in packing. The Kerr Nos. 1-3-5 or the S. S. White Nos. 
 34-36-39 answer the requirements and are satisfactory and sufficient 
 for usual cases. 
 
 Fig. 378. — Root canal pluggers. 
 
 Filling Material. — As a temporary sealing for the tooth between 
 appointments, base plate gutta-percha has many advantages. It is 
 easy to remove at the next sitting and if properly manipulated will 
 seal the cavity from moisture. However, care must be used to prevent 
 pressure upon the dressing or any contents of the canal which might 
 be injurious to the periapical tissue. Gutta-percha unless carefully 
 used will cause the fracture of the crown of the tooth weakened by the 
 extensive drilling necessary to thoroughly uncover the canals. The 
 
440 PREPARATION AND FILLING OF ROOT CANALS 
 
 most satisfactory method of sealing is gutta-percha beneath covered 
 well with temporary cement. Soft temporary stopping should not be 
 used for root-canal operations. 
 
 Requirements of a satisfactory root-canal filling are as follows: 
 
 It should be plastic so as to be easily manipulated and carried into 
 all parts of the canal. 
 
 It should not be irritating to the periapical tissue. 
 
 It should not absorb moisture. 
 
 It should be a non-conductor of thermal change. 
 
 It should not be soluble in the fluids of the body. 
 
 It should not shrink or change form after insertion. 
 
 It should be opaque to the Roentgen ray. 
 
 Up to the present time gutta-percha comes the nearest to meeting 
 the requirements of a successful root-canal filling material. It can be 
 made plastic by dissolving in chloroform or by softeiiing with heat so 
 that it can be forced and packed into all parts of the root canal. The 
 
 Fig. 379. — Gutta-percha cones. 
 
 addition of a few grains of resin or some antiseptic drug to the chloro- 
 form before adding the gutta-percha is recommended by some operators, 
 but the advantages claimed for such drugs seem to be of little value 
 and often they increase the difficulties of root-canal filling. The great 
 problem of root-canal filling is the removal of the organic matter from 
 the canal and wherever that may be removed gutta-percha can be placed 
 to mechanically fill the space. If organic matter is left in the canal it 
 will decompose and the presence of any drug is of little value to counter- 
 act the products of such decomposition. The ultimate purpose of 
 filling root canals is to completely fill them and to maintain a healthy 
 periapical tissue. This tissue is subject to injury by mechanical irri- 
 tation, by chemical action of drugs or by bacterial action when invaded 
 by virulent organisms which cause a destructive inflammation followed 
 by suppuration. The filling material should be selected with the con- 
 sideration of the efi^ect it might have upon the periapical tissue should 
 it escape through the apical foramen. The complete filling of the 
 
EQUIPMENT FOR ROOT-CANAL OPERATIONS 
 
 441 
 
 canal is of great iiii])()rtance and this is a very difHciilt tliiiii;" to accoiu- 
 plish without the escape of some of the material through the foramen. 
 Gutta-percha answers the requirements quite well. The tissue will 
 accommodate itself to it although a mechanical injury is produced 
 where it passes beyond the apical foramen. It does not absorb mois- 
 ture nor is it soluble in the tissue fluids. It will not shrink away from 
 the walls of the canal unless some other substance is added which will 
 dissolve or evaporate. Solutions of gutta-percha will shrink but short 
 pieces of gutta-percha (Figs. 374 and 379) softened and packed under 
 pressure into a dense mass will not shrink and the filling will be imper- 
 vious to moisture if it seals the canal at each end. 
 
 Fig. 380.— Operating tray. Aseptic tray from root canal instrument cabinet con- 
 taining complete equipment of instruments and materials used in the operation. Always 
 ready to use if sterilized before replacing in cabinet. 
 
 The Operating Tray. — The operating tray (Fig. 380) is simply a 
 sterile tray or perhaps a shelf removed from the root canal instrument 
 cabinet with sufficient room upon it to hold all the instruments and 
 materials necessary for the operation. There are two distinct advan- 
 tages in this plan. First, cleanliness and second, conxenience. If the 
 shelf or tray is prepared after each operation before replacing it in the 
 cabinet it is in readiness when needed with every instrument sterilized 
 and all sterile material in place upon it. This procedure encourages 
 carefulness and cleanliness in the operator and assistant and gives the 
 patient a feeling of confidence in the cleanliness of the operator and his 
 work. 
 
 Upon the tray should be the aseptic medicament tray and several 
 small porcelain minim trays for broaches of every size and style needed 
 for the operation, sterilized cotton pellets and absorbent points, metal 
 
442 PREPARATION AND FILLING OF ROOT CANALS 
 
 broach handles and root canal pluggers, an acid loop and a pair of 
 scissors and any other instruments or materials needed in the operation 
 
 (Fig. 380). 
 
 ASEPSIS IN ROOT-CANAL OPERATIONS. 
 
 Asepsis in root-canal operations is as important as it is in any surgical 
 operation. Doubtless, a large percentage of the infected conditions 
 found in the periapical tissue about the roots of teeth originated in 
 infection introduced dutinjg the operation of filling the root. At the 
 present time there is no way to differentiate between the various 
 causes of the infections found in the periapical tissue about the 
 roots of pulpless teeth. It is evident, however, that in a very large 
 percentage of all cases showing absorbed bone areas about the root 
 apices the root is not well filled. A careful survey of a large 
 number of roentgenograms of pulpless teeth and an accurate 
 record of the condition found show substantial clinical evidence in 
 favor of the right kind of root-canal filling. The report of such a 
 survey by Dr. Arthur D. Black,^ covering roentgenograms of 1500 
 root-canal fillings, shows an interesting record. Dr. Black classified 
 the fillings according to large and small canals and good and poor 
 fillings. The roots with large or small canals showing mechanically 
 good fillings had an evidence of periapical disturbances in only about 
 10 per cent, of them while the large or small canals showing poor fillings 
 gave evidence of periapical disturbance in about 65 per cent, of them. 
 This tabulation was made in 1918, and there is no doubt that a very 
 large percentage of the operations was completed before the campaign 
 for greater asepsis in root-canal operations had been generally effective. 
 It is safe to assume that with the aseptic precautions that are being 
 used in the operations of today a much better showing will be made in 
 a similar survey a few years hence. Root-canal fillings which the 
 roentgenogram shows to be mechanically perfect usually have a healthy 
 periapical tissue so with the proper methods of asepsis in these opera- 
 tions of today there should be a decided improvement in the future 
 record of results. 
 
 The Instruments and Materials. — Under the heading of Sterilizers, 
 several methods of sterilization of root-canal instruments and materials 
 were mentioned. The all-important point is that adequate steriliza- 
 tion must be used. It is not difficult to find suitable equipment for this 
 but it is somewhat difficult to work out a routine of practice that is practi- 
 cable and efficient. When constant use is made of different instruments, 
 all very small and hard to handle, the routine should be as simple as is 
 
 Journal American Medical Association, October, 1918. 
 
CLEANING AND ENLARGING THE CANAL 443 
 
 consistent with thoroughness so that adequate sterilization may never be 
 neglected by either assistant or operator. 
 
 The cabinet containing the root canal unit constantly subjected to 
 formaldehyde will maintain sterilization and keep instruments and 
 materials previously sterilized ready for immediate use. They may be 
 sterilized just previous to the operation if desired. There will not 
 be the danger of neglecting sterilization, however, when the cabinet 
 contains the instruments and materials always in readiness for use. 
 Here again the time-saviilg method of having a removable cabinet 
 shelf to use as an operating tray (Fig. 380) with all materials and 
 instruments arranged for the operation is a decided advantage. 
 
 The operation upon the root canal may now be begun in an aseptic 
 manner. To maintain asepsis during the operation the aseptic medica- 
 ment tray (Fig. 370) containing phenol and alcohol should be before 
 the operator constantly to dip the broach in each time before inserting 
 it into the canal. This should become a matter of unconscious habit. 
 
 Preparing the Field of Operation. — It is needless to say that the 
 rubber dam must be used in all cases of root-canal operatioQS. When 
 the tooth is badly broken down it becomes necessary to cement a thin 
 copper band around the tooth to support the clamp to hold the rubber 
 in place. If the band be properly fitted and cemented to place without 
 interference with the occlusion it may be left upon the tooth until the 
 root has been filled. There are special clamps for roots previously 
 prepared for dowel crowns which will crowd the gum back and grip the 
 end of the root in almost all cases, thus saving the time required to fit 
 a copper band. The canal should never be open without the rubber 
 in place. The rubber isolates the field of operation which is absolutely 
 necessary to perform an aseptic operation. Just before adjusting the 
 rubber the gums and teeth should be sprayed with an antiseptic wash 
 and tincture of iodin painted on the gum and teeth adjacent to the 
 tooth to be operated upon. When the rubber is in place the surface 
 of the teeth included within the field should be again washed with 
 tincture of iodin. 
 
 CLEANING AND ENLARGING THE CANAL. 
 
 1. Gaining Access to the Pulp Chamber. — ^The crown of the tooth 
 should always be cut away sufficiently to expose the entire pulp 
 chamber to view and show the openings of the canals. It is not possible 
 to successfully manipulate broaches around curves and angles, there- 
 fore as many as possible of such obstructions should be eliminated by 
 cutting away the enamel and dentin covering the pulp chamber. It is 
 far better to sacrifice a little tooth structure which obstructs root-canal 
 
444 PREPARATION AND FILLING OF ROOT CANALS 
 
 operations than to work at a great disadvantage and perhaps fail to 
 thoroughly clean and fill the canal. 
 
 Incisors and Cuspids. — Incisors and cuspids can best be treated 
 through a small opening near the center of their lingual surfaces. 
 However, when the tooth presents with a cavity on the mesial or distal 
 surface through which access to the canal may be obtained with very 
 little further cutting of the enamel it is better to make the entrance 
 through the cavity. When entering on the proximate surface the 
 opening of the canal should be cut well over toward the cavity to enable 
 easy entrance of the broach into the canal. Both mesial and distal 
 horns of the pulp chamber must be carefully opened and cleaned to 
 prevent subsequent discoloration of the tooth. 
 
 Bicuspids and Molars. — In exposing the pulp chamber of a bicuspid 
 or molar the tooth structure should be cut away according to the 
 requirements of each case. The occlusal opening on a bicuspid should 
 be extended buccally and lingually sufficiently to enable the operator 
 to see the mouth of each canal. The entire roof of the pulp chamber 
 should be cut away and the mesial wall beveled to facilitate access 
 with the instruments. The molar crown should be cut both in a bucco- 
 lingual and a mesio-distal direction according to the shape of the pulp 
 chamber and the location of the canal openings. The upper and lower 
 first molars require considerable cutting toward the mesio-buccal angle, 
 for usually the mesio-buccal canal is located directly under the apex 
 of the mesio-buccal cusp. The entire roof of the pulp chamber should 
 be cut away and frequently the wall on the buccal needs cutting back 
 because the canal lies so close in the angle of the pulp chamber. If 
 the tooth presents with a disto-occlusal cavity it is best to seal it with 
 cement and open directly on the occlusal surface cutting well to the 
 mesio-marginal ridge. Should the tooth contain a good filling on 
 the mesial surface extending on the occlusal surface it is better to 
 remove it and enter the pulp chamber with convenience than to leave 
 it to become an obstruction later and thereby interfere with the success 
 of the operation. Each tooth requires a little different cutting, for 
 there is a slight variation in the shape of the pulp chambers and 
 location of the canals of each. There is a marked variation in the first 
 and second upper molars. However, the location of the mesio-buccal 
 canal is usually directly beneath the apex of the mesio-buccal cusp. 
 The opening of the canals in the floor of the pulp chamber are usually 
 located so that if lines should be drawn connecting them they would 
 form the sides of a triangle (Fig. 381). 
 
 The opening of the canals should not be disturbed until the pulp 
 chamber is entirely opened so that all cuttings may be blown away 
 without allowing them to enter the canals to clog them up. Often it is 
 
CLEANING AND ENLARGING THE CANAL 
 
 445 
 
 necessary to bevel the mesial wall toward the mesio-marginal ridge and 
 cut away part of the buccal and lingual walls to bring the opening of 
 the canals into view. 
 
 B 
 
 c 
 
 D 
 
 Fig. 381. — The molar triangle. Imaginary lines drawn between canal openings in 
 pulp chamber. Drawings to illustrate location of canals in different forms of teeth. 
 A, B, C, upper molars; D, lower molar. 
 
 2. Gaining Access to the Apical Foramen. — The object of filling 
 root canals is to seal the apical foramen after the organic matter of the 
 pulp tissue has been removed. This objective can only be attained 
 when there is sufficient access to the foramen to enable the operator to 
 cleanse the canal thoroughly and pack gutta-percha into the space. 
 The large canals seldom give much trouble but the small canals like 
 the mesial canals of lower molars and the buccal canals of upper molars 
 and the upper first bicuspid canals are difficult to enlarge and cleanse 
 and when the roots are curved or there is secondary dentin present to 
 obstruct the canal the difficulty is greatly increased. 
 
 A B 
 
 Fig. 382. — Gaining access to the apical foramen. A, Drawing to illustrate curved 
 mesial root of lower molar. B, Drawing to illustrate straightening the canal. The 
 obstructing dentin should be removed to allow a straight instrument to pass as far as 
 possible, leaving only one curve to travel. Obstructing dentin at (a) should be carefully 
 filed and cut away without making a ledge in the dentin. 
 
 The process of cleansing and enlarging the canal also straightens 
 it and the more nearly straight it becomes the better access is obtained. 
 A careful study should be made of the roentgenogram of the tooth 
 before entering the canal and the obstructing dentin should be cut 
 away as much as possible to allow more direct entrance into the canal 
 (Fig. 382). When the finest broach will pass to the foramen of the 
 root, and it usually will if the attempt is made before any other instru- 
 
446 PREPARATION AND FILLING OF ROOT CANALS 
 
 merit has been inserted into the canal, the process of cleansing and 
 enlarging should be completed successfully and the canal filled perfectly. 
 There are many difficulties to encounter during the process of enlarge- 
 ment, such as packing debris into the apical third of the canal, making 
 a ledge on the side when the broach fails to follow a curve in the canal, 
 or losing the tip of a broach on a curve; anyone of these three mis- 
 fortunes makes the foramen inaccessible and a complete canal filling 
 impossible. A brief consideration of these difficulties follows: to 
 remove the debris from a canal does not seem to be a serious problem 
 and is not if the broach used for cutting is frequently removed and the 
 debris cleaned off. The files are very useful for enlarging but they do 
 not remove the debris very well, so it becomes necessary to follow them 
 with a very fine (XXX) barbed broach to rake out the filings and 
 shreds of organic materials. This is attended with considerable danger 
 of losing a point of the broach for the canal is very small and perhaps 
 curved and the slightest binding of the barbs upon the side of the canal 
 may cause a piece of the broach to break away and plug the canal at 
 that point. Another difficulty, that of making a ledge or losing the 
 canal, is caused by using too large a broach which will not follow the 
 curve in the root and consequently bores a depression in the dentin 
 at the curve instead of following the canal around the curve. When a 
 curve is encountered the walls must be carefully filed away with small 
 files to straighten the canal to give access to the foramen (Fig, 382). 
 The opening of the canal in the pulp chamber may be enlarged with a 
 small Gates-Glidden drill to facilitate locating it, but the point of the 
 instrument must always be kept in the canal to prevent making a false 
 pocket which would be a great handicap in the following operation. 
 The curves should be carefully filed away and the debris removed, using 
 the finest broaches until the foramen is reached. A broach should 
 never be used which is too large to pass to the foramen ^ach time until 
 the canal has been enlarged and straightened to remove the danger of 
 losing the canal and making a false pocket in the dentin. 
 
 3. Checking up by Roentgenogram.^ — A roentgenogram should be 
 made of every tooth requiring treatment before beginning the operation 
 in the pulp chamber or canals. Sometimes the roentgenogram will 
 show a condition which makes canal operations inadvisable because of 
 crooked roots or obstructed canals and very frequently the periapical 
 tissue will be found so badly diseased that the retention of the tooth 
 might be a menace to the general health of the patient. 
 
 When the operation is under way and there is some difficulty encoun- 
 tered or some doubt as to the progress of the operation it is well to insert 
 a wire in the canal allowing one end to be flush with the occlusal surface 
 of the tooth (Fig. 383) and, after sealing up the cavity with temporary 
 
FILLING THE CANAL 447 
 
 stopping, a roentgenogram should be taken to check up the work to 
 this point. This is a great aid to the operator and requires but very 
 little time and inconvenience especially where the operator makes his 
 own roentgenograms. 
 
 When the canal is ready to fill a small stiff root canal plugger like 
 Kerr No. 1 or the S. S. White No. 34 should pass to within three milli- 
 meters of the apical foramen (Fig. 384). The space between the end 
 of the plugger and the apical foramen is the most important portion of 
 the canal and the future health of the periapical tissue is largely depen- 
 dent upon the successful filling of this part of the canal, especially of the 
 larger canals. 
 
 4. Measuring Length of the Canal and the Diameter of the Foramen. 
 — The length of the canal is determined by the length of the measm-e 
 wire inserted before taking the roentgenogram. The roentgenogram 
 shows the relative length of the wire in comparison to the root. The 
 wire should be cut so that one end is flush with the occlusal surface 
 when it is in the canal. Frequently the roentgenogram gives an eloa- 
 gated or shortened picture of the tooth and the inaccuracy of the 
 picture can usually be estimated and added to, or deducted from, one 
 end because the other end of the wire is even with a definite surface 
 landmark from which measurement can be calculated. 
 
 The diameter of the apical foramen may be calculated by the size 
 of the plugger which will pass to it, or by an absorbent paper point 
 with the small end clipped off until it will just reach the foramen but 
 not pass through. 
 
 Now with the measure wire corrected to the proper length and with 
 a fairly close measure of the diameter of the foramen the filling of the 
 canal may be started. 
 
 FILLING THE CANAL. 
 
 When the canal has been thoroughly cleansed and enlarged to ac- 
 commodate instruments suited for packing gutta-percha to the apical 
 foramen it is ready for filling unless some complication is encountered. 
 The canal must be dry and aseptic and the apical tissue in a healthy 
 condition before a successful root-canal filling can be inserted. 
 
 The measure wire and the absorbent point used to ascertain the 
 length of the canal and the diameter of the foramen should be upon the 
 tray before the operator. The plugger which will pass to the apical 
 third of the canal should be marked or bent so as to show when it is 
 within three millimeters of the apical foramen when placed in the canal. 
 When it is in the canal as far as the mark, the operator has only to 
 estimate the small space between the end of the plugger and the fora- 
 
448 
 
 PREPARATION AND FILLING OF ROOT CANALS 
 
 men (Figs. 384 and 385). This is the most important part of the entire 
 fining and the more successful the operator is in thoroughly sealing 
 the apical foramen without injury to the periapical tissue the nearer 
 will the result approach a perfect operation. The gutta-percha cone 
 
 Fig. 383 Fig. 384 Fig. 385 
 
 Fig. 383. — Measuring length of canal. Wires flush with occlusal landmark. 
 Fig. 384. — Plugger No. 1 inserted in buccal canals. The bend in shank indicates the 
 distance necessary to insert. 
 
 Fig. 385. — Plugger to reach within 3 mm. of foramen. The space between the plug- 
 ger and the foramen is the most important of the entire space to be filled. 
 
 suitable for the canal should be selected and cut in pieces of about 
 three millimeters in length. It is necessary to use many more of the 
 small ends of the gutta-percha cone than the other pieces, therefore it 
 saves time to have a dish with compartments to contain cut cones of 
 
 Fig. 386 Fig. 387 Fig. 388 
 
 Fig. 386. — Plugger No. 1 carrying first piece of gutta-percha cone selected to seal the 
 apical foramen. Plugger is inserted to bend in shank and gutta-percha should just reach 
 the apical foramen and be large enough to prevent passing through the foramen. 
 
 Fig. 387. — First piece of gutta-percha cone packed in place sealing the foramen. If 
 measurement is accurate there should be no excess filling. The second piece is packed 
 against this with considerable pressure followed with piece after piece, until the canal is 
 full. 
 
 Fig. 388. — Canals filled. Short pieces added one by one in same manner, packing 
 each thoroughly until the roots are all filled. 
 
 different sizes (Fig. 374). The larger sizes, Nos. 3 and 6 (Fig. 379) 
 furnish the best first points to be used in plugging the foramen while 
 the smaller sizes 8, 10 and 12, furnish better pieces for filling the middle 
 third of the canal. 
 
FILLING THE CANAL 
 
 449 
 
 The point piece of gutta-percha suitable for plugging the apical 
 foramen should be selected and placed upon the end of the root-canal 
 plugger. The plugger should be heated slightly in the flame so that 
 the gutta-percha will adhere to it when pressed upon the larger end of 
 the piece. 
 
 The canal should be dry before filling. It should then be slightly 
 moistened with eucalyptol throughout its entire length. A very small 
 amount of chlorapercha may be carried into the canal to adhere to the 
 walls and to help in filling all the opea space in the apical portion of 
 
 '^ Fig. 389. — Wires measuring length of 
 lower molar canals. Tooth in position. 
 
 Fig. 390. — Root-canal plugger inserted 
 in distal canal. Bend at occlusal surface 
 marks the distance the plugger should be 
 inserted to reach within 1 mm. of foramen. 
 
 Fig. 391. — Canals filled. Distal canal divided into two branches. 
 
 the canals. The less clilorayercha used the more accurate should he the 
 result since it is impossible to prevent overfilling when much chlora- 
 percha is used. The large carals require less chlorapercha than the 
 small ones since the gutta-percha points can be packed clear to 
 the apical foramen of large canals with little difficulty. Now the 
 plugger carrying the selected piece of gutta-percha cone should be 
 inserted into the canal and forced slowly down till the mark or bend 
 indicates that it has gone to place (Fig. 386). If the measurement has 
 been accurate this will seal the foramen since the gutta-percha on the 
 end of the plugger should just reach the foramen when the plugger is 
 29 
 
450 PREPARATION AND FILLING OF ROOT CANALS 
 
 Fig. 392 
 
 Fig. 393 
 
 Fig. 394 
 
 Fig. 395 
 
 Fig. 396 
 
 Fig. 397 
 
 Fig. 398 Fig. 399 
 
 Figs. 392 to 399. — Root-canal fillings. Figs. 392 and 393 show branches of the main 
 canal have also been filled. 
 
RECORDING 451 
 
 inserted as far as the mark (Fig. 387) . This should be followed by 
 selected pieces of cut cones softening each slightly by warming and 
 packing them into the canal until it is filled. After sealing with a hot 
 burnisher the filling is complete. 
 
 A roentgenogram of the tooth should be made to prove the filling 
 (Fig. 388) and unless it is satisfactory it should be removed and the 
 canal refilled. 
 
 TO REMOVE ROOT FILLINGS. 
 
 A gutta-percha root-canal filling can be removed easily by heating a 
 small root-canal plugger or explorer and softening it as much as possi- 
 ble, then by flooding the pulp chamber with chloroform or xylol. The 
 last named drug will soften gutta-percha very rapidly but care must be 
 used to prevent it passing through the foramen, as it is quite irritating. 
 Xylol should never be sealed in the tooth. Chloroform or eucalyptol 
 may be sealed within the pulp chamber for twenty-four hours to a good 
 advantage in some cases. Root-canal fillings of cement are extremely 
 difficult to remove as this material is so hard that the instrument will 
 not follow it. Hydrochloric acid will sometimes assist but it must 
 be used with great care and must be neutralized with a solution of 
 sodium carbonate. The difficulty of removal is one of the chief 
 objections to the use of cement as a filling material for root canals. 
 
 RECORDING. 
 
 A complete record should be kept of every tooth having root-canal 
 operations, The record should begin with the condition of the pulp 
 and periapical tissue before the operations are begun. If we had a 
 record today of the condition of the periapical tissue surrounding the 
 teeth with root-canal fillings before they were inserted it would be 
 possible to differentiate between some of the causes of the absorptions 
 of periapical tissue. As we have not such a record we can only class 
 all absorptions together. A detailed daily record of the method of 
 pulp removal, the drugs used in the treatment and the method of seal- 
 ing the treatment in the tooth should be kept. A very useful form has 
 been suggested by Dr. A. D. Black of Chicago whereby such a record 
 may be kept with very little inconvenience and loss of time (Fig. 400) . 
 If we record the condition of the pulp and periapical tissue of each 
 tooth before the operation is begun and keep a complete roentgeno- 
 graphic record of the periapical tissue from the time of treatment, it 
 will be of great value in the history of pulpless teeth relating to the 
 development of future conditions. It is evident that every drug used 
 in the treatment of pulpless teeth has some effect upon the condition 
 
452 PREPARATION AND FILLING OF ROOT CANALS 
 
 DENTAL PULP CASE HISTORY 
 
 Patient's 
 Name 
 
 Age 
 
 Patient's 
 
 NtTMBEK 
 
 Address 
 
 Tooth. 
 
 Diagnosis. 
 
 Color. 
 
 Removal. 
 
 Treat- 
 ment. 
 
 Seal- 
 ing. 
 
 Root filling. 
 
 c 
 
 Subsequent 
 radiograph. 
 
 Color. 
 
 O 
 
 l-I 
 
 "3 
 H 
 
 o 
 a 
 
 "3 
 
 > 
 
 £ 
 
 p. 
 .a 
 "3 
 > 
 
 .2 
 
 "3 
 > 
 
 o 
 c 
 
 G 
 
 1 
 
 c 
 
 "3,-^ 
 
 
 
 £ 
 
 "3 
 £ 
 o 
 
 -d 
 
 1 
 
 "c 
 
 5 
 
 < 
 
 s 
 o 
 
 c 
 o 
 
 "3 
 
 ll 
 
 II 
 
 X r 
 r S 
 
 Oi 
 
 
 1 
 
 i 
 
 o 
 3 S 
 
 o o 
 
 Jo 
 
 
 
 d 
 
 3 
 
 d 
 
 1 
 
 !< 
 
 a 
 
 ci 
 
 X 
 
 - 
 
 .C 
 
 i i < ^ 
 
 ■6 
 
 
 
 
 
 
 
 
 
 
 
 
 ^ 
 
 
 i 
 
 1 
 
 - 
 
 
 
 
 
 
 
 
 - 
 
 
 
 
 
 
 
 
 
 1 ' ! 
 
 j 
 
 1 
 
 
 
 
 
 
 
 
 
 
 i 
 1 
 
 
 
 
 
 
 
 
 
 Fig. 400. — Dental pulp case history. Directions. This chart is printed on an 
 envelop, the illustration being actual size. The history is to be made out as the case 
 progresses; the radiographs of the case to be kept in the envelop. If the pulp is dead 
 or if the root has been pre^aously filled the patient is required to have a radiograph made 
 before treatment is begun. 
 
 1. Enter patient's name, age and address. 
 
 2. Indicate tooth by number or letter. 
 
 3. Diagnosis: (a) If the pulp is %'ital and normal and is to be removed because a croTvn 
 is to be made, or if it is accidentally exposed in cavity preparation, mark X in first 
 column. (6) If pulp is vital and is removed on account of hj-peremia which has developed 
 into inflammation, mark X in second column, (c) If pulp is \dtal and exposed bj' caries 
 or so nearly exposed that its removal is required, mark X in third column, (d) If pulp 
 is dead, mark X in fourth, fifth or sixth column, according to the condition shown by 
 the radiograph. It ■n'ill be considered a slight abscess if any injury to the bone is shown 
 and treatment is undertaken. It will be marked in column " Abs. Extract" if treatment 
 is not considered ad\-isable. (e) If there is a previous root filling, mark X in the last 
 column also an X in column four, five or six, according to the condition shown by the 
 radiograph. 
 
 4. Color of tooth: Mark X in proper column. 
 
 5. Removal of pulp: (a) If arsenic is applied, enter date in figures in proper column 
 as 5, 2, 16. (b) If cocain-pressure is used or novocain anesthesia, infiitration or conduc- 
 tive, enter date in proper column, (c) Enter date the pulp is removed in proper column. 
 This date is to be entered if arsenic was applied or if the tissues were anesthetized or if 
 the pulp was dead. 
 
 6. Treatment: Enter date of application of medicaments. If a second treatment of 
 the same drug is made, enter date on second horizontal, etc. Doubtless many dentists 
 would prefer to have other drugs entered in these column headings. 
 
 7. Sealing: Mark X in the proper column. 
 
 S. Root filling: (a) Mark in first column length of tooth from occlusal surface or 
 incisal edge in millimeters, making measurement with a fine smooth broach and using 
 a Boley gauge. If the crown is bioken off so state at bottom edge of envelop. Place 
 diagnostic wire and have radiograph made, (h) Mark date in second or third column to 
 indicate gutta-percha alone or chloropercha and gutta-percha used as root filling, (c) 
 If canal is inaccessible to apex, indicate by fraction y, f or f, etc., according to distance 
 
RECORDING 453 
 
 of the periapical tissue so it is of great importance that such a record 
 should be kept in the tooth history. The method of filling and the 
 material used should be recorded and any other remarks regarding the 
 nature or peculiarity of the case, which might have some bearing upon 
 future conditions, should be kept. Teeth should be saved, not all 
 diseased teeth, but teeth that are healthy or that can be made healthy 
 and it is the duty of the profession to master this great problem and 
 successfully cleanse and fill root canals so that they may be retained 
 with safety to function in mastication as nature intended. 
 
 diagnostic wire shows in radiograph, (d) Have radiograph made of root filling. Mark 
 X indicating whether it is considered a good or a fair filling. In case it is a poor filling 
 a new root filling should be made, also another radio.graph. (e) In cases of teeth ha\dng 
 more than one canal, use a separate horizontal line for each canal and indicate each by 
 writing the initials, as ni-l, m.-b, d-h, dis., ling., hxc., etc. 
 
 9. Resection: If root is resected, enter date in this column. 
 
 10. Subsequent Radiograph: It is the intention to send for patients to return in 
 about six months and make a check-up radiograph. When this is done the date should 
 be entered in the proper column, indicating the condition of the bone at that time. 
 Additional radiographs should be made after several j-ears. 
 
 11. Color. The color of the tooth will be marked by the date of a subsequent exami- 
 nation. — Dental Summary, October, 1919, xxxix, 749. 
 
CHAPTER X. 
 
 PATHOLOGY AND TREATMENT OF HYPERSENSITIVE 
 
 DENTIN. 
 
 By HERMANN PRINZ, M.D., D.D.S. 
 
 Hypersensitive dentin may be defined as a state in which the 
 exposed dentin of a vital tooth is painfully responsive to mechanical, 
 chemical, thermal and electrical irritation. The primary cause must 
 be attributed to its exposure to an irritant. Absence of enamel or 
 otherwise pathologically exposed dentin is the iritial condition essential 
 for its causation. Enamel, which protects the dentin of the crown, 
 may be absent as a result of incomplete calcification, or may be lost ■ 
 through pathologic processes — that is, caries, erosion, abrasion or 
 trauma, while the exposed dentin of the root of a tooth is primarily 
 brought about by premature or senile atrophy of its protective alveolar 
 process. 
 
 Pathology. — Before entering upon a discussion of the pathology of 
 hypersensitive dentin the anatomy and physiology of normal dentin 
 should be recalled briefly. Dentin is made up of about 72 per cent, 
 inorganic salts, about 10 per cent, water and an organic matrix con- 
 stituting the remaining percentage. The dentin is traversed by a very 
 large number of tubuli measuring about 1^ to 5 ^ in diameter aud radi- 
 ating from the pulp cavity, more or less wave-like, toward the peri- 
 phery, where they branch off, forming a deltoid network. Roemer has 
 counted from 25,000 to 30,000 dentinal tubuli within the area of a 
 square millimeter. The tubuli are filled with lymph and with the 
 protoplasmic processes of the odontoblasts, as originally described by 
 Koelliker, and they are known as Tomes's fibers. These fibers are 
 structureless threads and are continuous through the full length of the 
 tubuli and their branches. 
 
 Physiologically normal dentin has no sensation; its vital protoplasm 
 transfers tactile impressions, thermal changes and chemical or electrical 
 irritation to the pulp. 
 
 The so-called innervation of dentin is still a much mooted question. 
 
 Professor Hopewell-Smith interprets its present status as follows: 
 
 " It is an interesting and important fact that it has not yet been proved 
 
 to the entire satisfaction of all observers that nerve fibers exist in the 
 
 (454) 
 
PATHOLOGY 455 
 
 dentinal tubes. Thus there is a wide difference in men's views as to 
 the innervation or non-innervation of the dentin. One school of 
 belief, headed by Boll, Morgenstern, Roemer, Dependorf, Fritzsch 
 and Howard Mummery endeavors to explain sensitiveness to the 
 occurrence of peripheral nerve fibers in the dentinal tubuli, while the 
 other school denies the existence of nerve fibers in this tissue. Among 
 those included in this group are Retzius, Koelliker, Tomes, Huber, 
 Walkhoff, Gysi and Hopewell-Smith. By persistent search in teeth 
 of mammals and reptiles no definite nervous system has been dem- 
 onstrated, the nerve fibers terminating in arborizations around the 
 odontoblasts on the surface of the dental pulp. 
 
 Impulses are carried through the dentin to the pulp nia the contents 
 of the dentinal tubuli, i. e., dentinal fibrils, the peripheral processes of 
 the odontoblasts, and lymph. There is an abundance of protoplasm 
 in these innumerable channels. Members of the second school of 
 thought are divided in their views as to the causes of sensation. The 
 hylopathist ascribes it to abnormal movements of the molecules of the 
 dentinal fibrils while the others claim that demarcation currents, con- 
 vection and osmosis are responsible for pain. All, however, are agreed 
 that the cerebro-spinal nervous system has no share in its production 
 beyond that in the dental pulp." 
 
 Personally the author is in full accord with the concepts of the 
 second school of histologists, i. e., the non-innervation hypothesis of 
 dentin. From a pharmacologic point of view he is able to furnish 
 sufficient data to substantiate this assumption. Basing his own con- 
 ception upon this hypothesis, he assumes that hypersensitive dentin 
 denotes a state in which the contents of the dentinal tubuli are patho- 
 logically altered. This change is brought about by external physico- 
 chemical influences which interfere with surface tension, absorption and 
 diffusion. All three of these processes are closely allied phenomena. 
 
 According to Gibb's law all substances which lower the surface 
 tension of a solvent become more concentrated in the surface film than 
 in the interior. It is a phenomenon which depends upon the increase 
 of attraction of the molecules in the surface film for one another and 
 puts the film under pressure. Thereby a hydrostatic pressure is 
 created which materially increases the normal osmotic pressure. As a 
 rule inorganic neutral salts and many sugars raise the surface tension 
 very slightly, whereas acids, bases and most organic substances lower 
 the surface tension. The colloids concentrated in the surface film 
 become very viscous, finally forming a membrane insoluble in water. 
 Colloidal solutions readily absorb water and dissolve salts from the 
 surrounding medium. The absorption of water increases proportion- 
 ally with the concentration of the salt solution to a certain point and 
 
456 PATHOLOGY OF HYPERSENSITIVE DENTIN 
 
 thereby an increase in the internal pressure of the colloidal solution 
 is obtained. 
 
 Surface tension is constantly trying to reduce itself; in a uniform 
 fluid this is impossible, while in a mixture consisting of two or more 
 substances which in themselves possess different surface tension the 
 lighter fluid has a tendency to collect on the surface of the more tense 
 fluid. Under the influence of these different forces, dynamic equi- 
 librium is established within a certain time.^ These various factors 
 favor mechanical absorption, reduction of surface tension, increase of 
 solubility under pressure and compressibility of water. 
 
 Chemical absorption is of less interest in this connection. The most 
 important factor which influences absorption is the ion concentration 
 of a fluid. The equilibrium of a phase relative to its ion concentration 
 is controlled by the law of mass action. 
 
 The relative viscosity of a fluid plays a most important role. If the 
 surface of a solution absorbs a dissolved substance the viscosity of its 
 surface may be markedly increased. As a consequence albumins, 
 soaps, saponins, dyestuffs, etc., form a surface fllm which materially 
 interferes with the dift'usibility, as compared to pure water, of 
 dissolved substances. 
 
 When the colloidal contents of the dentinal tubuli become exposed 
 to the fluids present in the oral cavity their surface tension becomes 
 altered by absorption and diffusion in accordance with the above 
 enumerated physico-chemical processes; they become overdistended 
 and thereby exert pressure upon the underlying odontoblastic cells. 
 The fluids in the tubuli cannot be compressed as water possesses no 
 elasticity; it represents a rigid column which transmits pressure in the 
 form of motion undiminished in all directions. Any additional pres- 
 sure which is exerted upon the overdistended surfaces is at once trans- 
 mitted to the nerve filaments located at the sm-face of the pulp (the 
 plexus of Boll), that is, the anatomic threshold of sensation. 
 
 Cutting the enamel does not produce painful sensation. As soon as 
 the dento-enamel junction is reached, marked pain is usually exper- 
 ienced by the patient. Beneath the dento-enamel junction are located 
 the interglobular spaces of Czermak, which are filled with semifluid 
 protoplasm. Pressure and heat produced by the revolving bur upon a 
 relatively large surface area of fluid in this region are quickly trans- 
 mitted to the pulp, and hence pain is felt. Within the area of dentin 
 which lies beyond this zone, sensation is lessened until the advancing 
 bur reaches within close proximity of the pulp. In carious dentin, 
 excavation of the zones of complete disorganization and of decalcifica- 
 
 1 Decrease in surface tension is readily demonstrated by the following simple experi- 
 ment: to 100 c.c. of absolute alcohol contained in a graduated cylinder, add 100 c.c. 
 of distilled water. After equilibrium is established the mixture measures only 192 c.c. 
 
PATHOLOGY 457 
 
 tion does not produce sensation because the contents of the tubuU are 
 destroyed. As soon as the zone of turbidity is reached, marked pain 
 is manifested. Here the contents of the exposed dentinal tubuU are 
 subjected to intense irritation brought about by acidity and other 
 products of bacterial metabolism. The surface tension of the fluids 
 in the tubuli is altered markedly, hence the quick response to pressure 
 and thermal influences. Below this zone of turbidity the '^ translucent 
 zone of Tomes" is observed in chronic caries. This translucency of 
 dentin is the product of a vital reaction. The chronic irritation of the 
 odontoblasts causes the pulp to respond promptly by depositing 
 adventitious dentin within the lumen of the tubuli, which necessarily 
 lessens their diameter in varying degrees, or even produces complete 
 obliteration. Hence a smaller surface of the tubular contents is 
 exposed to the advancing bur, and, consequently, lessened sensation is 
 felt. The gradual reduction of surface area of the dentinal tubuli 
 is a physiologic process in the life cycle of a tooth, hence sensitiveness 
 diminishes with advancing age. 
 
 IMechanically abraded teeth or those subjected to the as yet little 
 known process of erosion are rarely hypersensitive in the later stages. 
 Abrasion and erosion are usually intensely chronic processes, hence 
 their very slow progress offers to the irritated odontoblasts sufficient 
 time to deposit adventitious dentin within the tubuli and thereby 
 protects the underlying pulp from further irritation. Sections of 
 mechanically or chemically abraded teeth containing living pulps 
 always show a translucent zone. 
 
 As stated above the process of removal of enamel of a sound tooth 
 by cutting and grinding, if done under proper precautions to avoid 
 undue heat, is usually not painful. The freshly exposed dentin is 
 relatively free from sensation. Within a short lapse of time, however, 
 usually mthin twenty-four hours, this exposed dentin is extremely 
 hj-persensitive. The exposure of the contents of the tubuli to the 
 ffuids of the mouth, as explained above, changes the sm-face tension 
 so as to cause pronounced irritation of the odontoblastic cells. 
 
 Dehydration of the overdistended tubuli by physical means relieves 
 the hypertension; consequently, such an agent as warm air reduces 
 the sensibility. Alcohol, potassium hydroxid or similar hygroscopic 
 chemicals act sjiichronically as dehydrants and caustics. Self- 
 luniting caustics, as silver nitrate, perhydrol, etc., superficially destroy 
 the vitality of the protoplasmic fibers, and they protect the contents 
 of the tubuli by solid plugs of precipitated albumin. The disturbing 
 elements are thereby permanently excluded from reaching the dentin. 
 The distiu-bed equilibrium of the tubular fiuid readjusts itself in a 
 short time and, consequently, hyperesthesia is relieved. A substantial 
 
458 PATHOLOGY OF HYPERSENSITIVE DENTIN 
 
 illustration of this fact is furnished by protecting immediately arti- 
 fically exposed dentin with a coating of silver nitrate or a temporary 
 cap set with gutta-percha and not with an irritating cement. Such 
 dentin will exhibit no particular sensation at any time after the 
 operation. 
 
 Any general condition which lowers the normal psychic reaction of 
 a patient naturally also influences the reactivity of the tooth pulp. 
 Therefore, such disturbances as acute nasal catarrh, influenza, exanthe- 
 matous fevers, increased intradental blood-pressure, menstruation, 
 anemia, general debility or certain neuropathic conditions, as neuras- 
 thenia, may leave their imprint upon the pulps in the form of congestive 
 hyperemia and, consequently, any irritation of the exposed dentin of a 
 tooth under these conditions is prone to exhibit indirectly excessive 
 sensibility. 
 
 From the above discussion of its pathology the author concludes 
 that hypersensitive dentin designates a state of irritation of the 
 odontoblasts of a vital pulp. Irritation is produced only by external 
 agents, i. e., physico-chemical processes induce changes in the surface 
 tension (hypertension) of the exposed contents of the tubuli. The 
 increased reactivity of the disturbed equilibrium transmits any 
 additional physical or chemical impulse at once via Tomes' fibers to the 
 congested odontoblastic cells covering the pulp, which are in direct 
 contact with the nerve fibers of the plexus of Boll, i. e., the anatomic 
 threshold of sensation. 
 
 Symptoms and Treatment. — The principal subjective symptom of 
 hypersensitive dentin consists of more or less severe pain, which is 
 usually elucidated by marked temperature changes, chemical irritation 
 or mechanical interference of the exposed dentin surface. The pain is 
 not continuous, it merely lasts as long as the irritant is present. The 
 patient may present a carious or otherwise defective crown of a tooth, 
 an exposure of its root or, frequently, an incomplete union at the 
 periphery of the enamel and cementum at its neck. The thermal 
 test with hot, and especially cold, water or pressure exerted by an 
 instrument placed upon the exposed surface of the dentin is very 
 pronounced. Changes in the color of the tooth, percussion, palpation 
 and roentgenogram are negative. Hypersensitive dentin offers good 
 chances for conservative treatment; under proper management it 
 may be eradicated readily. 
 
 The rational principle of treatment should be based on the recogni- 
 tion of its pathologic cause, that is, hypertension of the contents of the 
 dentinal tubuli. Any method or means which favors the readjustment 
 of the altered colloidal equilibrium and prevents further irritation of 
 the exposed dentin surface is useful for the purpose. 
 
SYMPTOMS AND TREATMENT 459 
 
 In general the remedies employed should conform to the following 
 requirements : 
 
 1 . The remedy must not injure the organic or inorganic constituents 
 of the tooth. 
 
 2. The remedy must not permanently interfere with the welfare of 
 the pulp. 
 
 3. The administration of the remedy must not require a complicated 
 instrumentarium . 
 
 4. The pharmacologic action of the remedy must be exhibited within 
 a few minutes. 
 
 5. The remedy must be readily applicable to all classes of cavities 
 with regard to their location. 
 
 6. The remedy must not produce pain. 
 
 7. Permanent discoloration of dentin must not occur. 
 For convenience, we may divide the applied remedies into: 
 
 A. Physical and chemical procedures: 
 
 1. Keen edged instruments. 
 
 2. Caustics. 
 
 B. Local and general remedies: 
 
 1. Local anesthetics and sedatives. 
 
 2. General anesthetics and sedatives. 
 
 Sharp Instruments.- — ^The superiority of sharp instruments over dull, 
 ragged-edged tools when working upon living tissue is generally 
 recognized by every-day experience. Sharp excavators cut without 
 much pain when employed with a definite, precise movement at right 
 angles to the long axis of the tubuli. Dull engine burs produce heat by 
 friction and by being held in too continuous contact with the cavity 
 wall. They should not only be sharp but run at high speed and 
 allowed to touch the surface very lightly as they revolve. A thin 
 coating of vaselin further reduces undue friction. 
 
 Caustics. — Caustics are substances which destroy living tissue by 
 virtue of their coarse chemical or physical action. This action may 
 manifest itself by abstracting water from albumin, by dissolution or 
 precipitation of the albumin, by oxidation or substitution. Caustics 
 which are employed for the purpose in view are principally dehydrants 
 and albumin solvents or precipitants. Alkalies containing hydroxyl 
 groups — KOH and XaOH — are very powerful albumin solvents, and 
 they are not self-limiting. The albumin precipitants are represented 
 primarily by the metallic salts, by certain organic compounds, as 
 phenol, alcohol, etc., and by heat. Mineral acids should not be applied 
 on living tooth structure for such purposes. The precipitates obtained 
 by metallic salts differ widely in regard to their density; silver nitrate, 
 
460 PATHOLOGY OF HYPERSENSITIVE DENTIN 
 
 for instance, produces a dry, dense scab, while zinc chlorid combines 
 with the albumin to form a loose, flocculent clot. 
 
 As we have stated above, hypertension of the contents of the dental 
 tubuli is the primary cause of hypersensitive dentin. The removal of 
 this tension will necessarily interfere with or prevent the transmission 
 of impulses; hence the most simple and most logical method of reducing 
 hyperesthesia of dentin for the purpose of excavating is to dispel the 
 moisture from the tubuli. It has been found that desiccation of a 
 cavity by subjecting it to a current of warm air in conjunction with 
 absolute alcohol will bring about a condition of immunity to sensation 
 in proportion as such desiccation is thorough or partial. To accomplish 
 desiccation of the dentin best the rubber dam should be adjusted to the 
 tooth and the greater portion of the carious mass carefully removed 
 with spoon excavators; the cavity should be bathed with absolute 
 alcohol^ and then subjected to a stream of warm air applied in some 
 convenient manner. The ordinary air syringe or chip-blower may 
 have its point heated in a flame, and then, by forcing the air in the 
 bulb slowly through the tube, a jet of warm air will be delivered into 
 the cavity. By holding the nozzle of the syringe at the proper distance 
 and having learned by experience how much heat to apply, one can 
 often inject a current of air into the cavity at nearly the same tempera- 
 ture as that of the tooth ; but if the air when it reaches the cavity should 
 be either perceptibly above or below the proper temperature, pain will 
 be produced. In some warm-air sjTinges the tube is provided with a 
 hollow receptacle somewhere along its length, which, when heated, 
 raises the temperature of the air within it before being directed into 
 the tooth cavity. Neither of these methods is at all exact, and either 
 is therefore liable to produce more or less pain in the act of dehydration. 
 A better plan would be to employ a sjTinge in which a coil of fine 
 platinum is contained within the orifice ; this coil is connected by wires 
 through the body of the syringe with a source of electric current; in 
 operation the resistance encountered by the current of electricity 
 passing through the platinum coil heats it and maintains a steady 
 temperature. Air forced over this coil and through the nozzle, especi- 
 ally air supplied from a receiver and under pressure that can be con- 
 trolled, may be heated to a temperature that will approximate very 
 closely that of the tooth, and therefore produce little or no pain. If the 
 air passing from the nozzle of the syringe should be too warm it can be 
 modified by holding it a little farther away from the tooth, or if not 
 warm enough, more heat will be delivered when it is held in closer 
 proximity. 
 
 1 Absolute alcohol for this purpose may be prepared by adding either J ounce anhy- 
 drous copper sulphate or an equal quantity of well-burned unslaked lime to 3 ounces of 
 commercial alcohol. 
 
SYMPTOMS AND TREATMENT 
 
 461 
 
 An instrument of this character with a compressible bulb instead of 
 an air supply from a receiver is represented in Fig. 401. The operation 
 of desiccation should not be hurried; time must be allowed for raising 
 the air to a suitable temperature, so as to cause as little pain as possible. 
 In addition the operation should be continued until the dentinal walls 
 of the cavity have become perceptibly lighter in color, indicating that 
 they have been robbed of their moisture. If desiccation is not carried 
 to this point it will fail in its effectiveness; but if the moisture has been 
 removed from the dentin to a considerable depth, as it may be if desic- 
 cation be continued sufficiently, sensitiveness will have become nearly 
 or entirely obliterated. Whether we depend entirely upon dryness to 
 relieve hypersensation or not it should be resorted to, for it proves a 
 most valuable preliminary means when it is to be followed by medica- 
 tion of anv kind. 
 
 Fig. 401. — Electric warm-air syringe. (Guilford.) 
 
 Caustic alkalies are preferably applied in the well-known form of 
 Robinson's remedy, which is composed of equal parts of potassium 
 hydroxid and crystalline phenol forming potassium phenate when 
 triturated together in a warmed mortar, with the addition of a very 
 small quantity of glycerin to render it plastic. It should be preserved 
 in well-stoppered bottles. A small quantity of this compound applied 
 to the previously dehydrated painful dentin surface and rubbed into 
 it with a warm burnisher will often prove to be of benefit. An intimate 
 pasty mixture of potassium carbonate, four parts, and pure glycerin 
 one part kept in a tightly corked bottle, has also been lauded very much. 
 The caustic and dehydrating effect of these agents combined with the 
 warm air blast lowers hyperesthesia markedly. 
 
 Their benumbing action, however, is only superficial, and they have 
 to be applied repeatedly as the preparation of the cavity progresses. 
 
 Albumin precipitants are principally represented by silver nitrate, 
 zinc chlorid and phenol. The silver salt acts very superficially and very 
 slowly. Incidentally, by combining with the chlorin present in the 
 
462 PATHOLOGY OF HYPERSENSITIVE DENTIN 
 
 albumin and in the presence of light, it produces jet-black discoloration 
 of the involved dentin. On all exposed dentin surface, especially on 
 the exposed roots of the posterior teeth where the resultant color is no 
 objection, it is an admirable desensitizer. It is best applied as a freshly 
 prepared saturated aqueous solution. Other silver salts are of less 
 value in this connection, as they are less caustic. It should be remem- 
 bered that the pharmaco-dynamic action of silver nitrate depends upon 
 the precipitation of albumin by the nitric acid ion and not upon the 
 silver ion. The latter merely combines with the albumin forming a 
 complicated double salt, i. e., silver-albumin chlorid, which in the 
 presence of light is partially reduced to a black oxid. Zinc chlorid 
 is an admirable desensitizer; its application in crystal form or as a 
 saturated solution is somewhat painful on account of its acid reaction. 
 As it is not self-limiting it should not be applied into deep-seated 
 cavities on account of the danger of pulp irritation at the time of its 
 application or subsequently. Liquefied phenol does not penetrate 
 deeply into tooth structure and may be applied safely to cavities of 
 any depth. When applied into a dehydrated cavity in conjunction 
 with the warm-air blast it produces quick and marked superficial 
 benumbing effects, hence it is widely employed for this purpose. The 
 addition of local anesthetics to phenol for this purpose, i. e., cocain, 
 etc., is an irrational procedure. 
 
 Within the last few years Buckley^ has lauded dry formaldehyde 
 (trioxymethylen) in the form of a paste as: "A new, safe and reliable 
 remedy for hypersensitive dentin." This empirically compounded 
 paste contains approximately 35 per cent, of dry formaldehyd mixed 
 with vaselin and a few minor substances of no direct value. Inter- 
 national dental literature of the last decade is filled with references 
 relative to the use of formaldehyd as a desensitizing agent, and all 
 writers, except Buckley, agree that it is a most dangerous agent for 
 this purpose, as it will injure and, in most instances, kill the pulp. 
 It produces numbness of dentin in the same manner as arsenic, only 
 acting somewhat slower. 
 
 Trioxymethylen acts as a non-self-limiting caustic which penetrates 
 comparatively quickly through any thickness of dentin.^ As an illus- 
 tration of the intense caustic action it may be stated that in the hands 
 of some practitioners the Buckley desensitizing paste constitutes the 
 routine application for the purpose of destroying the pulps in deciduous 
 teeth. The same deleterious results are obtained with the so-called 
 "Norwegian Dentin Anesthetic." This compound contains carpain 
 
 1 Items of Interest, December, 1914. 
 
 2 Prinz: Dental Cosmos, August, 1915. 
 
SYMPTOMS AND TREATMENT 463 
 
 and paucin, two alkaloids which act somewhat like erythrophlein, i. e., 
 they kill the pulp. 
 
 Occasionally, protoplasmic poisons are recommended for the pm'pose 
 of desensitizing dentin. In many instances these drugs are referred 
 to erroneously as caustics. A protoplasmic poison should be designated 
 as a drug which endangers, or even kills living cell structure without 
 visible changes. Protoplasmic poisons are not self-limiting in their 
 action. Arsenic trioxid and, to a less extent, the alkaloids nervocidin, 
 erythrophlein and paucin, are the principal substances of this group 
 that have been employed as desensitizing agents. Arsenic when 
 applied even in the very minutest quantities will usually kill the pulp, 
 as its action cannot be controlled. This is equally true of the above- 
 named alkaloids; they have only historical interest at present. 
 
 Local Anesthetics and Sedatives. — ^True local anesthetics, cocain or 
 its substitutes, when applied to exposed sound dentin without pressure, 
 do not produce any pharmacologic effects. Even if sealed into a fairly 
 deep-seated cavity in which the underlying dentin is not decalcified 
 no effect is obtained. Living protoplasm reacts unfavorably against 
 the ready absorption of substances by endosmosis for two reasons: 
 (1) the albumin molecule is relatively very large and is not easily 
 diffusible, and (2) it possesses, as an integral part of its life, vital 
 resistance toward foreign bodies. According to Hertwig, protoplasm 
 primarily transfers irritation and, secondarily transmits absorbed 
 materials. Therefore the anesthetic solution has to pass through the 
 entire length of tbe dentinal fiber before the nerve tissue of the pulp 
 proper is reached. Consequently a certain period of time is required 
 before the physiologic effect of the anesthetic is manifested and the 
 period of this latency is dependent upon the thickness of the inter- 
 mediate layer of dentin. The migration of a protoplasmic poison 
 through dentin may be observed by adding a vital stain to it, as, for 
 instance, methylene blue added to arsenic or dry formaldehyd. The 
 time required for its passage through about 5 mm. of sound adult 
 dentin is twenty-four or more hours. The pharmaco-dynamic power of 
 a drug depends upon its reaction with the living protoplasm through the 
 catalytic action of ferments. The decomposition of the absorbed drug 
 occurs comparatively quickly, usually within a few minutes. These 
 observations are seen daily on injecting anesthetics or other solutions 
 hypodermically. An average hypodermic dose of cocain is completely 
 decomposed by the ferments of the protoplasm within the period of an 
 hour, i. e., its typical local anesthetic effect is manifested within a few 
 minutes after the injection. The anesthesia remains at its height for 
 about thirty minutes, and from then on it diminishes until by the end 
 of the hour there is fairly complete recovery of normal sensation. 
 
464 PATHOLOGY OF HYPERSENSITIVE DENTIN 
 
 Therefore, if we apply cocain to sound dentin it is decomposed on its 
 passage over Tomes' fibers before it reaches the anatomic threshold 
 of sensation, i. e., the nerve plexus at the surface of the pulp, and 
 hence no anesthesia is produced. The nature of the cocain salt, whether 
 it is a hydrochlorid, nitrate or lactate, has no bearing upon its therapeu- 
 tic action. The apparent results obtained with these cocain salts must 
 be attributed to the preliminary dehydration, protection of the exposed 
 dentin by a temporary filling, etc., and not to its therapeutic effects. 
 This is equally true in regard to most of the heterogeneous mixtures of 
 cocain with other substances, as, for instance, potassocoin, vapocain, 
 etc. Again, in the widely recommended solution of cocain (alkaloid) 
 in chloroform and ether the cocain base plays no part. The apparent 
 results obtained are produced by the process of evaporating to dryness 
 and thereby obtaining a marked reduction in temperature, which is the 
 obtundent factor. When cocain or any of its substitutes is forced into 
 the living protoplasm of the unobstructed dentin tubuli under pressure, 
 its anesthetic action is manifested within a few minutes. The vital 
 resistance of protoplasm is readily overcome by comparatively slight 
 force, which quickly transfers the anesthetic solution by an increased 
 osmotic interchange to the surface of the pulp. The phenomenon is 
 to be explained as an anesthesia obtained by intimate contact under 
 pressure, either mechanical or by electromotive force (cataphoresis) . 
 The pulp of a tooth and, consequently, the dentin may be desensitized 
 completely by any one of the well-known methods of contact anesthesia 
 by using hand pressure or that derived from a dental hypodermic 
 syringe or some other more complicated apparatus or by electricity. 
 (See chapter XII.) 
 
 Electric Endosmosis. — Some years ago cataphoresis, for the purpose 
 of desensitizing dentm, was much lauded. This process consists of 
 placing a concentrated solution of cocain on cotton in the sensitive 
 cavity and having it carried along the dentinal tubuli toward the pulp 
 by means of a galvanic current, i. e., by electromotive force. A battery 
 is employed with the negative electrode, the cathode, inserted in the 
 cavity, and the anode placed upon some part of the patient's body, as 
 the band, etc. The current carries the cocain via Tomes' fibers into 
 the pulp and anesthetizes it. While in this condition, which usually 
 lasts for an hour or more, the tooth may be worked upon without any 
 pain. For a while this method met with great favor because of the 
 perfect results obtained, but it was found to be a very slow process, 
 requiring a cumbersome apparatus and often consuming more time 
 than the operator had at his command, and occasionally requiring a 
 second application in order to produce complete anesthesia; hence at 
 present it has been largely discarded. 
 
SYMPTOMS AND TREATMENT 465 
 
 Of the numerous essential oils which have been suggested as obtun- 
 dents of dentin, oil of cloves stands out prominently. 
 
 Its pharmacologic action depends on the presence of eugenol, an 
 unsaturated aromatic phenol. The basic constituent of eugenol 
 consists of para-amido-benzoic acid, a body which as such does not 
 exhibit any marked therapeutic effects. Its methyl ester, anesthesin, 
 is an efficient local anesthetic; however, it is only slightly soluble in 
 water. Einhorn and Uhlfelder, taking anesthesin as a base for their 
 synthetic research, finally succeeded in preparing para-amido-benzoyl- 
 diethyl-amino-ethanol, commercially known as novocain or procain, 
 which at present is the most efficient substitute for cocain. 
 
 Essential oils, in general, possess marked penetrating power. How- 
 ever, upon a fairly thick layer of sound dentin they are of little value 
 when employed as obtundents. A different pharmaco-dynamic action 
 is observed with arsenic. Arsenic trioxid, AS2O3, in the presence of 
 certain ferments of living protoplasm, i. e., oxydases and catalases, is 
 changed to the pentoxid, AS2O5, which again is quickly reduced to the 
 trioxid. This perpetual oxidation and reduction within the protoplasm 
 of the cell causes a violent oscillation of the molecule of active oxygen, 
 and thereby its therapeutic effects are manifested. The metalloid 
 arsenic merely plays the role of an auto-oxidizer. The presence of the 
 absorbed arsenic can be detected in the tissues by chemical analysis, 
 that of absorbed cocain cannot. 
 
 Among the local sedatives, refrigerant anesthetics should be men- 
 tioned. These agents lower the temperature, diminish sensation and 
 reduce the volume of the parts to which they are applied. 
 
 Physically reducing hyperesthesia of dentin by the application of 
 cold is best accomplished by employing a chemical which has a low 
 boiling-point. Pure ether (boiling-point 95° F., 35° C), free from 
 water, produces good results. Certain other hydrocarbons possess 
 similar properties in varying degrees, depending upon their individual 
 boiling-point. Pure ethyl chlorid (boiling-point 55° F., 13° C.) is 
 best for this purpose, as it lowers the temperature of the tissues suffi- 
 ciently to produce a short, superficial anesthesia in a few minutes. 
 Too rapid cooling or prolonged freezing produces deep anesthesia, but 
 such procedures are dangerous; circulation in the pulp may be cut off 
 so completely as to produce death. Liquid nitrous oxid, liquid carbon 
 dioxid, and liquid air, all of which have a boiling-point far below zero, 
 are recommended for such purposes, but they require cumbersome 
 apparatus, and some of these agents are extremely dangerous to handle. 
 
 In general, it should be stated that the application of cold for the 
 purpose of obtunding hypersensitive dentin is a barbaric procedure. 
 The initial pain produced by the cold is, in many instances, most 
 30 
 
466 PATHOLOGY OF HYPERSENSITIVE DENTIN 
 
 intense and more pronounced than that experienced by cutting the 
 untreated dentin. 
 
 Indirectly, hyperesthesia of dentin may be ehminated completely 
 by blocking locally the sensory nerve fibers leading to the pulp of the 
 respective tooth. Any one of the well-known methods or combinations 
 of methods, i. e., infiltration and conduction anesthesia, is available 
 for this purpose. On an average, most satisfactory results in a single 
 tooth are obtained by using the pericemental injection, provided the 
 pericementum is sound. (See Chapter XII.) 
 
 The paralj^zation of the central end-organs in the brain by a general 
 anesthetic will also anesthetize all the tooth pulps. Nitrous oxid is 
 possibly more often used for this purpose than any other anesthetic 
 agent. The much-lauded " analgesia" of a few years ago was, as might 
 have been expected, a failure. With the improvement in the various 
 methods of local anesthesia, general anesthesia for this specific purpose 
 has lost much of its former significance. 
 
 The control of hypersensitive dentin by the administration of 
 narcotics or sedatives is called for rarely. Of the general sedatives 
 the bromids are usually recommended. Large, continuous doses are 
 required to manifest their action, as they impair the perception of 
 sensory stimuli only to a very mild degree. Average doses of morphin 
 require at least one-half hour before a depression of the sensory impulse 
 is manifested, while chloral hydrate shows a marked lowering within 
 ten to fifteen minutes. Morphin-scopolamin administered hypoder- 
 mically causes most pronounced general narcotic effects and, of course, 
 marked lowering of the sensory reaction of the pulp. 
 
 Sensation in a tooth may be measured experimentally by passing a 
 weak electrically induced current through it, and the above data are 
 based upon observations obtained by such measurements. 
 
 Recently the author has been informed that certain practitioners 
 advocate painless operations about the teeth by administering such 
 powerful narcotic mixtures as morphin-scopolamin (hyoscin), also 
 known by various trade names. These drugs are intended to imitate 
 what is known in general surgery as "twilight sleep." Such procedures 
 are eminently dangerous. It should be remembered that ''doses of 
 these drugs, which without the aid of one of the gaseous anesthetics 
 cause a narcosis of sufficient depth, carry with them greater dangers 
 than any of the other various methods of producing anesthesia." 
 The author most emphatically discourages such practice. The 
 dentist who, on account of ignorance, administers powerful narcotics 
 of this type may suddenly find himself entangled in the meshes of the 
 law. 
 
CHAPTER XL 
 
 DISCOLORED TEETH AND THEIR TREATMENT.^ 
 
 By HERMANN PRINZ, M.D., D.D.S. 
 
 Pigments which cause discoloration of a tooth may be classified 
 as endogenous pigments, pigments formed within the tooth, and 
 exogenous pigments, pigmentary substances acquhed from external 
 sources. In the great majority of cases, endogenous pigments are 
 the source of permanent tooth discoloration and are obtained from 
 the blood. Temporary discoloration from endogenous pigments is 
 occasionally observed as a sequence of general diseases, as Asiatic 
 cholera, acute exanthematous skin eruptions, typhus fever and similar 
 distiu-bances which produce a pinkish color or in pronounced cases 
 of jaundice (icterus) a diffusion of bile pigment (bilirubin, which is 
 isomeric with hematoidin) may occur in teeth having living pulps 
 which produces a distinct orange-yellow stain. These various stains 
 usually disappear with the termination of the underlying disease. 
 Exogenous pigmentations usually result from the application of drugs 
 employed in the treatment of teeth, from medicines, from food or from 
 che'^ing stimulants, such as tobacco, betel nuts, etc. 
 
 Death of the pulp is the principal source of permanent discoloration. 
 While this does not always nor necessarily invoh^e discoloration of the 
 tooth structures, yet when the condition does exist the general cause is 
 as stated. Progressive interstitial staining of the entire dentin struc- 
 ture is the usual result, exclusive of certain metallic stains, also localized 
 stains resulting from the imbibition of pigmentary matters occasionally 
 observed when small areas of dentin have become denuded of enamel 
 covering or when the latter has been so imperfectly formed as to afford 
 an insufficient barrier to the ingress of pigmentary matters from the 
 food or oral secretions. 
 
 Three classes of conditions are presented for consideration and 
 treatment: (1) discoloration which has resulted from death of the 
 pulp due to causes other than its exposure; (2) discoloration from death 
 of the pulp caused by exposiue; (3) special discol orations from death 
 of the pulp due to adventitious causes superadded to the conditions 
 affecting the cases included in the foregoing second division. 
 
 1 The greater portion of this chapter has been written for former editions by Dr. 
 Edward C. Kirk. 
 
 (467) 
 
468 DISCOLORED TEETH AND THEIR TREATMENT 
 
 DISCOLORATION FROM DEATH OF PULP DUE TO CAUSES 
 OTHER THAN EXPOSURE. 
 
 Any of the numerous traumatic causes which bring about death 
 of the pulp, viz., blows, sudden contact with hard substances, biting 
 threads, violent thermal shocks, the injudicious application of con- 
 tinuous force in regulating, the application of arsenous oxid to the 
 dentin, where no exposure or only minute exposure of the pulp exists, 
 organic or inorganic poisons, certain bacteria or even the exposure to 
 severe cold (ethyl chlorid), may produce hyperemia and congestion 
 of the pulp, or strangulation of its circulatory system, the formation 
 of emboli, thrombus, hemorrhagic infarct, etc., leading to a breaking 
 down of the corpuscular elements of the blood, the escape of hemo- 
 globin from the stroma of the red corpuscles, its solution in the blood 
 plasma, and resulting infiltration of the tubular structure of the dentin 
 by the hemoglobin solution, giving the tooth a distinctly pinkish hue 
 when examined by direct light or by transillumination. An interesting 
 observation relative to tooth discoloration is made by Thomas Bell.^ 
 He states: "I have frequently examined the teeth of persons whose 
 death has been occasioned by hanging or drowning, and have invariably 
 found the whole of the osseous part colored with a dull deep red, which 
 could not have been the case if these structures were devoid of a 
 vascular system. In both instances the enamel remains wholly free 
 from discoloration." 
 
 Suffusion of the dentin structure by discharged hemoglobin may be 
 produced readih^ by the topical application to the exposed pulp of medi- 
 caments having hemolytic properties; for example, spirit of trinitro- 
 glycerin (glonoin) as an ingredient of a cocain solution intended for the 
 production of local anesthesia, will frequently produce hemolysis with 
 suffusion of the dentin when the mixture is applied locally to a bleeding 
 pulp. Even distilled water exerts a hemolytic effect, rupturing the 
 stroma of erythrocytes by endosmosis; therefore, all solutions intended 
 for topical application to a bleeding pulp should be at least isotonic 
 with the plasma or preferably of greater density in order to avoid 
 staining the dentin with diflfused hemoglobin. 
 
 Teeth so affected 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. 
 
 The violence of the hyperemia preceding the death and disintegra- 
 tion of the pulp determines, to a considerable degree, the rapidity of 
 
 1 Anatomy, Physiology and Diseases of the Teeth, 3d Am. Edition, Philadelphia, 1837. 
 
DISCOLORATION FROM DEATH OF PULP 469 
 
 the process of subsequent tooth discoloration. When congestion of 
 the pulp has been relatively slight and the necrotic process has pro- 
 ceeded 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 illumi- 
 nation, 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, even- 
 tually grow darker, and while they may not acquire a degree of dis- 
 coloration equal to those which have suffered sudden or violent death 
 of the pulp, they become so unsightly as to demand treatment for the 
 restoration of their normal color. 
 
 The Rationale of the Process of Discoloration. — In teeth discolored as a 
 consequence of the death of the pulp without its exposure it is evident 
 that the sources of pigmentation are internal to the tooth and are 
 sought for solely in the products of decomposition of the elements of 
 the pulp tissue and 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 decomposi- 
 tion, 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 
 histologic 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 corpuscles contain as their charac- 
 teristic component hemoglobin or oxyhemoglobin depending upon 
 whether the blood is venous or arterial, and this substance is its essen- 
 tial 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 
 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 extravasated blood 
 
470 DISCOLORED TEETH AND THEIR TREATMENT 
 
 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 bloodvessels and lymphatic system of the 
 part. 
 
 In passing through the cycle of color changes due to its progressive 
 decomposition, hemoglobin undergoes several alterations in com- 
 position, among which are formed a number of definite compounds, 
 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 gradual decomposition 
 of the coloring matter of the blood here noted may 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 (Hammersten), 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 hydrogen 
 sulfid is conducted through fresh blood or a solution of oxyhemoglobin 
 in the presence of air or oxygen, sulfomethemoglobin is formed, which 
 is greenish red in concentrated solutions and green in dilute solutions. 
 If we la}^ a recently 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 tempera- 
 ture 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, gangrenosa, etc., or even in inflammatory conditions of 
 less importance, 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 the belief that a combination 
 takes place resulting in the formation of this same compound, which 
 Miller regards as productive of certain stains upon the external surface 
 of the teeth. 
 
 The slaty gray or bluish pigmentation always noticeable upon the 
 visceral walls and frequently beneath the skin of animal bodies under- 
 going putrefactive decomposition is a familiar example of the action 
 
DISCOLORATION FROM DEATH OF PULP 471 
 
 of hydrogen sulfid or its ammonia combinations upon decomposing 
 hemoglobin in hemorrhagic extravasations, 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 pidp. "When red corpuscles are just beginning to disintegrate, 
 the coloring matter formed is hemoglobin; but the yellow and brown 
 granular masses foimd in cells and lying free in tissues are, as a rule, 
 derivatives of hemoglobin, not hemoglobin itself. These derivatives 
 are divided into two groups depending upon whether or not they con- 
 tain iron, the former being called hemosiderin, the latter hematoidin. 
 When acted upon by ammonium sulfid (a derivative of putrefactive 
 decomposition of albumin), hemosiderin becomes black, iron sulfid 
 being formed."^ Hemosiderin is a mixture of pigments in which iron 
 exists in a most accessible form to be demonstrated readily by the 
 Prussian-blue reaction. Grohe^ believes that as a result of putrefaction 
 iron is liberated from its compound with hemoglobin, so that when 
 thus freed it combines readily 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 
 constituent of the red corpuscles which is the essential chromogenic 
 factor from first to last in their cycle of color changes. 
 
 The process of putrefactive decomposition consists of a series of 
 chemical changes brought about through the agency of microorgan- 
 isms, involving the breaking down, by successive stages, of highly 
 complex organic compounds and their resolution into compounds of 
 much simpler composition. It is not known to what extent this split- 
 ting up of the components of the pulp and its vascular elements is 
 ultimately carried in the series of changes resulting in the permanent 
 discoloration of the tooth. From what is known of the ultimate compo- 
 sition of the compounds involved, it may be inferred that reduced to 
 its lowest terms, the residt so far as pigmentation is concerned, would 
 be the formation of iron sulfid, the elements of which, with the excep- 
 tion of some unimportant alkaline and earthy salts, are the only ones 
 entering into the original compounds which are fixed and therefore 
 capable of forming a stable residuum in the tubular structure of the 
 dentin. While iron sulfid cannot be held wholly accountable for the 
 final bluish-black color of a tooth, the pigmentation is almost certainly 
 due to it or to some allied compound in which iron and sulfm', with 
 some organic constituents, largely enter, and which, by a further 
 slight decomposition, would yield true iron sulfid. 
 
 1 Ziegler: General Pathology, 1895. 
 
 2 Virchow's Archiv, Band xx. 
 
472 DISCOLORED TEETH AND THEIR TREATMENT 
 
 The significance and importance of a recognition of the possible 
 presence of the iron compound as a factor in tooth discoloration are 
 further brought out in the stud}^ of bleaching methods. 
 
 Discoloration of Teeth Following Death of the Pulp Consequent Upon 
 Its Exposure. — When death and decomposition of the pulp are conse- 
 quent 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 
 may aftect the character of the resulting discoloration. Thus, the 
 yellowish 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 original sufi^usion of the dentin by hemo- 
 globin has not taken place ordinarily and, moreover, the progress of the 
 putrefactive process is comparatively rapid, the conditions being more 
 favorable, so that the coloring matter of the blood is sooner reduced 
 to its lowest terms in the scale of decomposition products, i. e., to the 
 slaty blue or black pigmentation before noted. The pigmentation of 
 the dentin in cases of pulp exposure with subsequent decomposition 
 of that organ is due to the diffusion of some of the decomposition 
 products of hemoglobin that have been formed in the pulp chamber and 
 not in the tubuli as in the class of cases first considered. In addition 
 to the increased rapidity of putrefactive decomposition incident to 
 cases of discoloration following pulp exposure, another important modi- 
 fying factor in the process of discoloration is the ingress afforded to the 
 oral fluids, food materials, and other adventitious substances which 
 find their way into the mouth, and ultimately, through the open 
 cavity of the tooth, to its pulp canal, and thence to the tubular struc- 
 ture of the dentin. These extraneous substances, in the course of time, 
 may infiltrate the tooth structure, and while no especially noticeable 
 or characteristic effect may be observed so far as color is concerned, yet 
 frequently they 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. 
 
 Fatty or oily substances or astringent and coagulant agents, for 
 example, may act upon the coloring matter in such a way as to set 
 it permanently in the same manner that mordants form insoluble 
 compounds or lakes with the dyestuffs used in the dyeing of textile 
 fabrics. 
 
DISCOLORATION FROM DEATH OF PULP 473 
 
 Another important class of substances which is frequently the cause 
 of staining the tooth structure is metallic salts used in dental thera- 
 peutic treatment or accidentally formed during the application of 
 corrosive medicaments to the teeth, through the action of such reme- 
 dies upon fillings in situ or upon the instruments by which the applica- 
 tions are made. An example of this is the use of iodin or sulfuric acid 
 or other metallic solvents in connection with steel instruments and the 
 subsequent use of medicaments containing tannin as an ingredient. 
 
 Treatment. — ^The treatment of these conditions will be considered 
 separately. 
 
 Teeth Suitable for the Bleaching Operation. — In deciding upon the 
 advisability of attempting the bleaching operation in any given case, 
 the general conditions which determine the action of the operator with 
 respect to all dental operations should govern his course. 
 
 As most therapeutic and restorative measures in dentistry are a 
 series of compromises with disease conditions or their sequelae, it is 
 usually the duty of the operator under the circumstances to capitulate 
 upon the basis of greater advantage to the patient. Therefore, if 
 discoloration of a tooth is practically the onl}^ 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 frac- 
 ture has not been so great as to preclude a satisfactory restoration by 
 proper filling or replacement of the lost structure by a porcelain inlay 
 or other material. 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 useless to attempt the bleach- 
 ing 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, due to the thickness of their walls and 
 the consequent depth of the structure requiring treatment. It is also 
 held to be useless to attempt the bleaching of teeth which have been 
 discolored throughout their structure by metallic stains. 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. 
 
 While teeth discolored by metallic stains present problems of great 
 complexity and require not only 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, in 
 
474 DISCOLORED TEETH AND THEIR TREATMENT 
 
 justice to the patient the attempt should be made to bleach them, even 
 though ultimate failure results, in order that the necessity for destruc- 
 tion of the natural crown for the purpose of its replacement by an 
 artificial substitute may be postponed, if possible, for as long a period 
 as may be attainable. 
 
 Nature of the Problem Involved in Tooth Bleaching. — The bleaching 
 process is dependent upon a chemical reaction between a compound 
 having color and some substance capable of so affecting its composition 
 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. For this 
 very reason, the process of bleaching is extensively employed in the 
 industries to textile fibers, to straw, paper stock, feathers, hair, oils and 
 fats, etc. 
 
 The substances concerned in discolor ation of tooth structure, as has 
 been previously shown, are derived from the pulp and its vascular 
 elements and the organic contents of the tubular structure of the 
 dentin, 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 arrange- 
 ment of a molecule having its individual group of chemical and physical 
 properties, among which latter is a characteristic color. If the surface 
 of a body possesses the property of reflecting the combined spectrum 
 of the sunlight without decomposition, that body is recognized upon 
 our retina as white. If, however, the surface possesses the power of 
 neutralizing a part of the projected white sunlight, i. e., to decompose 
 it, and to reflect its remaining part, the body will now be recognized by 
 the retina as that color which is the characteristic property of the 
 predominating reflected light rays, viz., red, or green, or blue, etc. 
 
 Whatever brings about an alteration in the composition of a 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 staining of a 
 tooth by means of an agent capable of effecting an alteration in the 
 atomic arrangement of composition of the color molecule, we may expect 
 incidentally to remove or discharge its color feature. 
 
 Two general classes of substances have been used successfully 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 
 
DISCOLORATION FROM DEATH OF PULP 475 
 
 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 congeners iodin and bromin act as indirect oxidizing 
 bleachers; the dioxids of hydrogen and of sodium are direct oxidizers. 
 Potassium permanganate may be classed also with this group, although 
 its successful use as a bleaching agent depends upon a subsequent 
 treatment of the substance to be bleached with some solvent capable 
 of removing 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. 
 
 The only agent belonging to the group of reducing bleachers which 
 thus far has been found available for bleaching teeth is sulfur dioxid, 
 either in the gaseous state or in aqueous solution. 
 
 Chlorin as a Bleaching Agent. — The general use of chlorin as a bleach- 
 ing 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 its use for bleaching 
 teeth into a coordinated sj^stem, was by the late 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 cavity of decay in the tooth. Chlorin is 
 liberated from the bleaching powder by the action of dilute acetic acid. 
 When this takes place in contact with the discolored tooth, it is bleached 
 rapidly as a result of the action of the chlorin upon the coloring matter 
 contained in the dentinal tubuli. Numerous modifications of this 
 original method of bleaching tooth structure have been suggested, but, 
 as the ultimate result in each is accomplished tlirough 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 the 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 combination with a number of them, under favorable circum- 
 stances, with great energy — forming, as a rule, compounds that are 
 soluble in water. 
 
 One of the distinguishing features, and one which is directly con- 
 cerned in its use as a bleaching agent, is a strong affinity for hydrogen. 
 So strong is this affinity, that when a molecule of chlorin is brought 
 
476 DISCOLORED TEETH AND THEIR TREATMENT 
 
 into contact with a molecule of water under favorable conditions, the 
 hydrogen of the water molecule is seized upon by the chlorin to form 
 chlorhydric acid, and the oxygen is set free in the nascent state, a 
 condition under which its oxidizing powers are exhibited in their greatest 
 intensity. This powerful affinity of chlorin for hydrogen enables it to 
 decompose many other hydrogen-containing molecules in a similar 
 manner, forming 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 
 important constituent. This applies also to the decomposition pro- 
 ducts whose presence in the tubular structure of the dentin is the cause 
 of tooth discoloration. 
 
 These organic stains exhibit the property of color by virtue of certain 
 definite conditions of molecular composition; hence, when chlorin acts 
 upon the coloring matter in the tooth by seizing upon and combining 
 with the hydrogen of the organic pigment, the identity of the com- 
 pound 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 the 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 
 hydrochloric acid; thus: CI2 + H2O = 2HC1 + O. That such is the 
 nature of the process in many cases is a reasonable deduction from the 
 behavior of chlorin under analogous conditions when it acts indirectly 
 as an oxidizing agent. 
 
 Whatever may be the exact natiu-e of its ultimate action, it is to be 
 borne in mind that the bleaching effect is due solely to the alteration 
 which is made in the composition of the color molecule and that there 
 is no solvent power whatever on the organic matter upon which it acts. 
 Chlorin changes its characteristics, but does not remove the molecule 
 by solution. It should be noted also, 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 compounds — the oxids and sulfids, for example. Hence it is 
 that when stains owe their color to the presence of certain organic 
 compounds with some of the metals, or even when the coloration is due 
 to decomposition products of hemoglobin, the color may be discharged 
 
DISCOLORATION FROM DEATH OF PULP 477 
 
 readily by chlorin; but if the iron chlorid thus produced by the action 
 of chlorin on the iron constituent of the hemoglobin remains in the 
 tooth structure, it is gradually decomposed and new combinations of it 
 are to occur, which result in a return of the discoloration. 
 
 All tooth-bleaching methods should aim not only to discharge the 
 color by suitable chemical means, but to remove all organic debris 
 and by-products of the bleaching process from tubuli, for as long as 
 any remain, the tendency to a return of the discoloration is always a 
 possible menace to the permanent success of the operation. However, 
 care should be exercised in the removal of the organic constituents of the 
 tooth structure so as not to weaken it unduly. 
 
 When the tubular contents cannot be removed successfully, the 
 tendency to a return of discoloration may be combated by hermetically 
 sealing the tubular orifices with an impermeable resinous varnish or 
 by permanently coagulating them. This feature is described more 
 fully in relation to the details of the bleaching procedure. 
 
 Preparation of the Tooth for the Operation of Bleaching. — It is neces- 
 sary to observe certain general details in the preparation of teeth for 
 the bleaching operation, whatever may be the method of treatment 
 employed. 
 
 Appropriate treatment for the removal of all septic matter from 
 the pulp chamber and canal, and for the relief of any existing conditions 
 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 which permanent closure of the apical foramen of the root 
 may be performed safely. 
 
 The rubber dam should be adjusted with si>ecial care and should 
 include only the tooth to be bleached. If two adjoining teeth are to 
 be bleached, both may 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 all cases desirable, 
 there are good reasons why such a plan should not be pursued in the 
 bleaching procedure. The chemicals used for the purposes may 
 possibly have some disintegrating or solvent action upon the enamel 
 structure and such action, should it occiu-, should be confined strictly 
 to the tooth undergoing treatment and held within the limits of safety 
 by close observation and appropriate treatment, which conditions can- 
 not be controlled as thoroughly and the process managed as satisfac- 
 torily when several teeth are included in the field of operation. 
 
 Furthermore, as nearly all of the bleaching agents used, or those 
 which are employed as adjuvants to the process have a more or less 
 irritative or escharotic effect upon the soft tissues of the mouth, extra 
 
478 DISCOLORED TEETH AND THEIR TREATMENT 
 
 precautions must be taken in adjusting the dam against leakage at its 
 attachment to the cervix of the tooth. For the reason that the chances 
 of leakage are greatly multiplied when several holes are punched in the 
 dam for adjustment to as many teeth, 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 carried 
 gently 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 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 the center by making six or eight turns of the 
 thread loosely around the end of the index finger of the left hand. 
 
 Fig. 402 
 
 Upon withdrawing the finger there is a series of loops through which 
 one of the free ends of the thread is now passed, as in making the first 
 half of a flat knot, as illustrated in Fig. 402. 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 the knot as described shall be 
 located 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 
 labio-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 dam and gingival margin, the 
 ligatm*e at the same time being drawn tightly until the anatomic 
 constriction of the tooth at its cervix will serve to hold it from slipping 
 downward, especially upon the palatal aspect of the tooth. 
 
 When the ligature is found to be securely placed as described, the 
 
DISCOLORATION FROM DEATH OF PULP 479 
 
 knot upon the labial aspect is completed and further enlarged by retying 
 the thread four or five times. The free ends of the ligature should be 
 cut off close to the knot. As an additional safeguard against leakage 
 of irritating bleaching agents through the cervical attachment of the 
 dam upon the soft tissues, it is well, after making the tooth perfectly 
 dry, to paint the ligatiu-e and a narrow band of its adjacent territory 
 with chloropercha, which, after evaporation of the solvent, will effectu- 
 ally prevent any accident from leakage. No clamps must be used, as 
 chlorin acts directly upon the steel forming soluble salts. 
 
 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 secm-ely against slipping downward, but holds it away 
 from the palatal sm-face which is ordinarily the point of entrance to 
 the pulp chamber and canals in these cases. The point of canal 
 entrance, however, may be through a proximate cavity, if such a one 
 affords sufficient access. 
 
 The canal filling in all cases of bleaching, without exception, should 
 be gutta-percha. Xo 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 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 crowTi. This is especially necessary when more or less recession 
 of the gum from its normal attachment has occurred, leaving the 
 cervical cementum exposed to the action of the oral fiuids, 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 procedm*e which 
 should not be omitted in any case, but where any bleaching method is 
 used which invoh'es the employment of chlorin as the active agent it 
 becomes necessary for reasons which are explained in connection with 
 the description of the chlorin methods. Aside from other considera- 
 tions, the removal of all fillings preparatory to the bleaching operation 
 has a decided value in facilitating the process by exposing an increased 
 area of dentinal structure and thereby permitting the action of the 
 bleaching agent over a larger territory of ingress. 
 
 When all fillings or softened tooth structure have been removed by 
 mechanical process, as well as all septic and extraneous matter of 
 w^hatever character, the tooth should be washed thoroughly with 
 dilute ammonia water, or better, with a hot saturated solution of borax 
 in distilled water. The object of this treatment is to remove by 
 
480 DISCOLORED TEETH AND THEIR TREATMENT 
 
 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, on opening into such a pulp chamber 
 for the first time, a dark layer of oily or greasy material lining its walls. 
 The thorough removal of this dark layer should be effected 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 excavators or round 
 burs in the engine. The thorough removal of this layer necessitates 
 free access to the pulp chamber, which, as a general rule, should be 
 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. 
 
 After he has effected a thorough cleansing of the tooth by mechanical 
 means and through the agency of borax or ammonia and hot distilled, 
 water, the operator should dry it to the extent of removing all super- 
 ' fluous moisture. Then the tooth will be in condition for the applica- 
 tion of whatever method of bleaching may be chosen for the particular 
 case in hand. When sodium dioxid or Schreier's kalium-natrium with 
 hydrogen dioxid is to be used as the bleaching agent, the preliminary 
 saponification of the canal contents with ammonia or hot borax solution 
 becomes unnecessary. 
 
 Truman's Method. — ^This, as before stated, was the first method 
 successfully employed for bleaching teeth. It consists of liberating 
 chlorin from ordinary chlorinated lime by means of a weak acid in the 
 pulp chamber of the tooth. Any acid will effect the liberation of 
 chlorin from the bleaching powder, but acetic, tartaric, or oxalic acids 
 are generally used. Care must be observed in selecting a good quality 
 of bleaching powder, as that substance rapidly undergoes spontaneous 
 decomposition, especially in a moist atmosphere. Good chlorinated 
 lime is a dry powder having a strong odor of chlorin which should con- 
 tain not less than 35 available per cents. 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 they are invariably contaminated with metallic chlorids due to the 
 slow action of the contents upon the container. The return of dis- 
 coloration in many cases after bleaching by the Truman method is 
 undoubtedly due to the use of bleaching powder so contammated. 
 The powder dispensed in glass bottles or in paraffined paper cartons is 
 more reliable. 
 
DISCOLORATION FROM DEATH OF PULP 481 
 
 Its application to the tooth may be effected in several ways: 
 
 (a) By packing the dry powder in the pulp chamber and then 
 moistening the latter with the acid. 
 
 (b) By mixing the powder with sufficient distilled water to make a 
 coherent mass which is more easily manipulated, then packing it in 
 the pulp chamber and applying 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 carrying 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 zinc 
 oxyphosphate if desired, but it is usually unnecessary to use anything 
 other than gutta-percha or one of the soft temporary stopping materials 
 for the pm'pose. 
 
 The case may be dismissed for one or two days and the treatment as 
 outlined repeated at similar intervals until the tooth is restored to 
 normal color. 
 
 The instruments used in connection with this process should be of 
 vulcanite, bone, ivory or wood. Under no consideration should steel, 
 gold, or platinum instruments be used, as chlorin acts directly upon 
 each of these metals, forming soluble chlorids, which, if carried into the 
 tooth structure, will give rise to a permanent staining of most intract- 
 able character. The only metals which may be used safely in connec- 
 tion with any chlorin process of bleaching are zinc and aluminum, the 
 chlorids of which are colorless, but, nevertheless, they are objectionable 
 for the reason that both are coagulant and color mordants. Aluminum 
 instruments for the purpose may be improvised quickly out of wire or 
 heavy plate. Gold instruments have been recommended but they are 
 open to the very grave objection of forming a chlorid by direct combina- 
 tion with chlorin, which salt is one of the most important staining media 
 known to the histologist; as a matter of fact, the author 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 bleaching, and there is certainly no reason why the same 
 result should not follow the using of gold instruments in the same 
 connection. 
 
 It is good practice to bleach the discolored tooth a shade or two 
 31 
 
482 DISCOLORED TEETH AND THEIR TREATMENT 
 
 lighter than its mate, as a bleached tooth usually darkens slightly in a 
 short time. 
 
 When the tooth has been restored to its proper color it should be 
 washed thoroughly with liberal quantities of very hot distilled water, 
 dried out with bibulous paper, and thoroughly desiccated with a 
 current of dry hot air, after which the canals, pulp chambers, and 
 cavities should be filled with zinc oxychlorid. 
 
 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 period may be 
 prolonged to four or six months with advantage. 
 
 The final washing of the tooth with hot distilled water previous to 
 the insertion of the zinc oxychlorid filling is a feature of the operation 
 which requires special care and attention. As left after the application* 
 of the bleaching agent, the pulp chamber and canals and dentinal 
 structure are filled with free chlorin in solution, iron chlorid from the 
 combination of the chlorin with the iron element of the color molecule, 
 calcium acetate, or other salt of calcium, depending upon the nature 
 of the acid used in the process and probably some undecomposed 
 bleaching powder. These substances should be removed thoroughly 
 by the hot water douche. At least a pint of water should be injected 
 strongly into the interior of the tooth by means of a large bulb sj^ringe 
 or other convenient means, before the dam is removed. A thick towel 
 or a suitable basin held in close proximity to the tooth will catch the 
 water as it returns from the tooth and protect the clothing of the 
 patient. Distilled water should be used in all cases for this iirigating 
 douche, as river water and many other specimens of water from natural 
 sources contain iron in solution, which could readily become a con- 
 taminating factor, leading to subsequent return of discoloration. 
 
 Zinc oxychlorid is selected as the permanent filling for the pulp 
 chamber, for the reason that it is necessary so to act upon the bleached 
 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 indefinitely. 
 A mass of zinc oxychlorid, before it sets, that is, before chemical com- 
 bination takes place between the zinc oxid 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 
 
DISCOLORATION FROM DEATH OF PULP 483 
 
 debris in the tubuli is as stated, and the material, if the operation has 
 been performed successfully, is effectually prevented from further 
 alteration, upon which condition the permanence of the operation 
 depends. 
 
 Another method for preventing subsequent alteration of the bleached 
 organic debris in the tubular structiue is to desiccate the tooth thor- 
 oughly by means of the hot air blast and saturate the dentin with some 
 insoluble resinous varnish, such as copal ether varnish, or, still better, 
 the solution of trinitrocellulose in methyl alcohol and amyl acetate, 
 known in commerce as ''kristaline," or in the market as "cavitine." 
 The pulp chamber and canals may then be filled with any suitable 
 filling. 
 
 As between the zinc oxychlorid filling and the varnish lining, the 
 choice in general should be of the former. The varnish lining is adapt- 
 able to cases of long standing, where complete liquefaction of the 
 tubular contents had left them practically empty, and where, as a 
 consequence, there is nothing upon which zinc chlorid can exert its 
 coagulating effect. 
 
 Other Chlorid Methods. — The solution of chlorinated soda known as 
 Labarraque's solution, or liquor sodse chloratse U. S. P., may be 
 applied to the previously desiccated tooth structiue until the dentin 
 is saturated with the solution, after which an application of a dilute 
 acid which liberates chlorin is made. The chemical principles involved 
 are analogous to those upon which the methods with bleaching powder 
 depend, the only difference being that the source of the active agent, 
 chlorin, is in one case its calcium compound, which is a dry powder, 
 and in the other the analogous soluble sodium compound. 
 
 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 nor 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, Virginia. This 
 involved the use of a complicated apparatus by which a continuous 
 jet of chlorin was thrown into and about the tooth. 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. 
 
 lodin. — Reference has been made previously to iodin as a bleaching 
 agent. Its chemical action is nearly analogous to that of chlorin, 
 though less energetic. In slight discolorations, however, iodin often 
 may be used to considerable advantage by simply satm^ating the 
 dentin with an alcohol solution of iodin, viz., the official 7 per 
 
484 DISCOLORED TEETH AND THEIR TREATMENT 
 
 cent, tincture, until the tooth structure is stained a characteristic 
 yellow. Then the cavity is sealed temporarily with a gutta-percha 
 filling and the case dismissed for twenty-four hours, at the expiration 
 of which period a marked improvement in color will be observed. 
 The same precaution is necessary in the use of iodin for bleaching 
 purposes as with the use of chlorin in regard to the removal of metallic 
 fillings and the avoidance of contact with metallic instruments. 
 
 Bleaching by Means of the Dioxid of Hydrogen and 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 has 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 treatment 
 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 structiue of a discolored tooth Imight^be 
 restored successfully to normal color. 
 
 Nascent oxygen may be furnished by two kinds of auto-oxidizers — 
 one direct source is its allotropic form known as ozone, and the other 
 is represented by the many dioxids, chiefly hydrogen dioxid, and those 
 of the alkali and alkaline earth metals. The nascent oxygen obtained 
 from both sources is based on the same principle of formation. 
 Ozone = 0—0—0, or O3, is split up in O2O (nascent state). 
 
 A dioxid, X— O— O, or XO2, is split up inXO— O (nascent state). 
 
 According to Nernst, the formation and the association of ozone are 
 illustrated by the following equation: 
 
 03^02+0 
 
 02 7!;o +0 
 
 Only one of the three atoms of the ozone molecule enters into active 
 or atomic oxygen, the other two forming molecular or inactive oxygen. 
 This is true of the oxygen molecule of a dioxid, one atom is set free 
 while the other one remains combined with the metal in the form of an 
 oxid. The ozone molecule and the dioxid molecule play the role of a 
 single atom of oxygen in the reaction of oxidation. The amount of 
 available oxygen in a dioxid depends on the degree of superoxidation of 
 the original oxid. Ozone, as well as the]^dioxids, are endothermic 
 compounds, that is, they require energy in the form of heat or electricity 
 for their formation. They are comparatively easily decomposed, 
 liberating again the same amount of energy in the form of heat which 
 was absorbed in their formation. Ozone has, thus far, been produced 
 
DISCOLORATION FROM DEATH OF PULP 485 
 
 only as a gas, while the dioxids, with the exception of hydrogen dioxid, 
 are solids. Oxygen obtained from ozone is usually produced by electric 
 energy at the place of its consumption ; it is an unstable gas which, for 
 practical purposes, cannot well be stored. The dioxids are usually 
 fairly stable compounds; they furnish any fixed amount of oxygen, if 
 so desired, at any moment and are in reality transportable accumulators 
 of available oxygen. Atomic oxygen — oxygen in its nascent state — 
 has a free valency; it cannot remain in that state, but energetically 
 seeks to combine with organic matter. This powerful affinity for every 
 oxidizable substance, including albumin, is known as oxidation, or 
 when accompanied by heat and light, as combustion. 
 
 The earlier dioxid preparations were found to be lacking in strength; 
 aqueous solutions containing more than 3 or 4 per cent, of absolute 
 hydrogen dioxid were 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. 
 
 Subsequent to the introduction of the pyrozone preparations, the 
 firm of Merck has produced a 100-volume solution of hydrogen 
 dioxid under the trade name of perhydrol, which is the most active 
 and efficient of the hydrogen dioxid preparations as tooth bleaching 
 agents. Aside from the ordinary 3 per cent solution of hydrogen 
 dioxid, higher concentrated solutions are found on the market. A 25 
 per cent, solution of hydrogen dioxid in ether is known as caustic 
 pyrozone, and a 30 per cent, solution in water is known as perhydrol, 
 or as peraquin. Caustic pyrozone is put up in glass tubes containing 
 a few cubic centimeters, while perhydrol is marketed in paraffin-lined 
 bottles of various sizes. In opening a pyrozone tube, great care should 
 be exercised to prevent explosion by placing the tube in cold water 
 and wrapping it in a wet towel before the end is broken off. Its con- 
 tents must be transferred at once to a glass-stoppered bottle, provided 
 with a ground cap, to prevent evaporation of the ether. Perhydrol 
 solution is to be greatly preferred whenever a highly concentrated 
 solution of hydrogen is desired. It is a chemically pure solution of 
 H2O2 in distilled water, furnishing about 30 per cent, by weight or 
 100 per cent, by volume of available oxygen. It is absolutely free from 
 acid, and may be diluted with water or alcohol to any desired strength. 
 Solutions should be made fresh as needed. If carefully preserved in 
 the original container and stored in a cool place perhydrol will retain 
 its oxygen for some time. Very recently, hydrogen dioxid in dry form, 
 known as perhydrit, has been placed on the market. Perhydrit is a 
 compound of hydrogen dioxid and urea, containing about 30 to 35 
 per cent, of available hydrogen dioxid. It is a very unstable compound. 
 
486 DISCOLORED TEETH AND THEIR TREATMENT 
 
 Any soluble dioxid compound intended for bleaching purposes should 
 be tested for its oxygen content. A simple test is made as follows: 
 mix ten cubic centimeters of distilled water with ten drops of dilute 
 sulphuric acid, one drop of potassium chromate test-solution (one part 
 potassium chromate dissolved in sufficient water to make one hundred 
 cubic centimeters), and two cubic centimeters of ether. On the 
 addition of the solution containing hydrogen dioxid, a blue color will 
 appear at the line of contact which will, after shaking, separate with the 
 ethereal layer. 
 
 Hydrogen dioxid, H2O2, belongs to the class of oxidizing bleachers, 
 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 
 liberate one of its oxygen atoms. In contact with pus, blood, inspis- 
 sated mucus, albumin, and in fact, almost every kind of organic 
 matter, its decomposition takes place, liberating oxygen and decompos- 
 ing the organic matter either wholly or in part. Hydrogen dioxid does 
 not bleach all of the decomposition products of hemoglobin with equal 
 facility. It quickly removes the pink discoloration following the initial 
 extravasation of hemoglobin into the dentin, but when the brown stage 
 has been reached, indicative of the formation of hematin, its action is 
 but slight. Later, however, it bleaches more readily. The refractory 
 nature of hematin with respect to hydrogen dioxid has been tested 
 experimentally upon the substance out of the mouth. 
 
 It is important to note that all acids promptly convert hemoglobin 
 into hematin, which is highly resistant to the action of hydrogen dioxid; 
 therefore, whenever hydrogen dioxid is used to bleach a tooth in the 
 primary or pivot stage of discoloration the hydrogen dioxid should be 
 made alkaline with sodium carbonate or hydroxid to neutralize at least 
 its usual slight acidity, otherwise its acid content will act upon the 
 hemoglobin, converting it into hematin, and thus set the color in such 
 a way as to be invulnerable to the action of the hydrogen dioxid. 
 
 In bleaching discolored teeth with hydrogen dioxid, perhydrol or 
 the ethereal 25 per cent, solution known as pyrozone is applied 
 directly to the internal portions of the tooth upon small pledgets of cot- 
 ton or cotton wisps rolled upon a fine flexible canal instrument. After 
 each application the menstruum is evaporated by blasts of warmed 
 air from a hot air syringe, and the applications similarly made are 
 repeated until the desired effect is produced. It has been found in 
 practice that more rapid and permanent effects are produced when the 
 solution is rendered alkaline. This may be done readily by the 
 addition of a few drops of liquor ammonise fortior or by a solution of 
 one of the caustic alkalies, namely, sodium or potassium hydroxid or 
 
DISCOLORATION FROM DEATH OF PULP 487 
 
 sodium dioxid. A very satisfactory method of securing the alkahue 
 effect in this process is that suggested by Dr. D. N. McQuillan. His 
 method is to treat first the pulp chamber and canals with applications 
 of Schreier's kalium-natrium preparation and after the debris from its 
 action has been mechanically removed with instruments and cotton 
 twists, without washing the canal, an application of pyrozone is made. 
 The bleaching action follows with great rapidity, and has apparently 
 greater permanence than when the pyrozone is used alone. In cases 
 in which 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 treatment 
 will usually complete the operation. 
 
 In this, as in all bleaching operations, it is advisable to fill the tooth 
 temporarily with some filling which may be easily removed m order to 
 test the permanence of the 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 filled permanently. 
 
 Harlan's method consists in acting upon hydrogen dioxid by alumi- 
 num chlorid. The aluminum salt is packed in the cavity and moistened 
 with the dioxid. Experimental study of the reaction between alumi- 
 num chlorid and hydrogen dioxid by Dr. E.G. Kirk developed the fact 
 that oxygen and no chlorin was given off, and that the aluminum 
 chlorid was unaltered during the process. Hence it was discovered that 
 the reaction was due simply 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 hydrogen dioxid is applied directly. 
 
 The Sodium Dioxid Method. — Sodium dioxid, Na202, is the chemical 
 analogue of hydrogen dioxid, and like the latter is characterized by the 
 readiness with which it parts with its atom of loosely combined oxygen 
 under similar circumstances. The essential difference in its properties 
 is the character of its by-product after its decomposition has taken 
 place. Being a strong caustic alkali, sodium dioxid still retains its 
 alkaline 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 vege- 
 table 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 contained organic matter, whether normal or in a 
 state of decomposition. Having the oxidizing and consequently the 
 
488 DISCOLORED TEETH AND THEIR TREATMENT 
 
 bleaching quality in addition 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 always applied to the dentin in 
 saturated solution, and never in the solid. In making the solution 
 special care is necessary in order to avoid raising 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 1 ounce capacity, about 2 drams of distilled 
 water, and immersing the beaker in a larger vessel or dish containing 
 iced water or pounded ice. The can containing the dioxid powder 
 should then have its lid perforated with a number of small holes 
 similar to the lid of a pepper shaker, and the powder should be dusted 
 slowly into the distilled water in the small beaker; or the powder may 
 be dropped gradually into the water by tapping it from the point of a 
 knife or spatula. The powdbr is added to the water until the solution 
 assumes a semi-opaque appearance, indicating the point of saturation. 
 
 On removing the beaker from the cooling mixture, the dioxid solution 
 in a few minutes will assume a transparent, straw-colored appearance 
 and is ready for use. 
 
 The applications are to be made similarly to those of hydrogen 
 dioxid, but upon asbestos fiber instead of cotton, as the latter is acted 
 upon by the sodium dioxid and converted into a glue-like material, 
 which is difficult to remove and which interferes with the success of the 
 operation. 
 
 After the dentin, which should have been desiccated previously, is 
 thoroughly saturated with the dioxid solution, an application of 
 10 per cent, sulfuric acid should be made, which neutralizes the 
 strong alkali, forming sodium sulfate and hydrogen dioxid, thus : 
 
 Na202 + H2SO4 = Na2S04 + H2O2. 
 
 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 be 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. 
 
 Sodium dioxid solution, as prepared for bleaching, may be applied 
 
DISCOLORATION FROM DEATH OF PULP 489 
 
 to the pulp chamber and root canal without the preliminary treatment 
 required where other bleaching agents are employed. It is without 
 harmful irritative action upon the apical tissues unless used in excess 
 or forced through the foramen by careless manipulation. It is a power- 
 ful germicide and disinfectant, and therefore peculiarly suited to the 
 treatment of putrescent cases, which, by its action, are rendered sterile 
 and aseptic as well as bleached at one operation. Its saponifying and . 
 solvent properties remove completely the greasy dark layer of decom- 
 posed material which is found lining the pulp chamber and canals, 
 alluded to previously, so that the use of the sodium dioxid method 
 makes unnecessary the preliminary application of borax or ammonia 
 for its removal. When sodium dioxid is used for its sterilizing property, 
 the foramen should be allowed to remain unsealed until after the 
 bleaching operation has been completed. It happens sometimes that 
 the improvement in color following the application of the dioxid 
 methods is only partial, and the result falls short of restoration to 
 normal ; or, in other words, the bleaching reaches a certain point beyond 
 which the color resists the further action of the bleaching agent. In 
 such cases the decomposition of the color molecule has probably 
 resulted in the formation of iron oxid as an end-product. In practice 
 this residual discoloration can be removed generally by treatment 
 with oxalic acid. A small crystal is to be sealed in the moist pulp 
 chamber for twenty-four hours, and afterward washed out with a 
 copious irrigation of hot distilled water. 
 
 The sodium dioxid method removes the tubular contents more 
 completely than any other method, and the result is unique from the 
 fact that not only is the tooth restored to normal color, but to normal 
 translucency; the opaque 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 satm-ated 
 as thoroughly as possible with an unalterable varnish before the final 
 filling is inserted. 
 
 The Sulfur Dioxid Method. — Reference has already been made to 
 sulfur dioxid as the single example of the reducing t^^pe of bleaching 
 agent. Its activity is due to its affinity for oxygen, and it bleaches 
 by seizing upon, and combining with, that element of the color molecule, 
 thus destroying its identity and consequently its color. Attempts 
 have been made to utilize the bleaching property of sulfur dioxid in the 
 treatment of discolored teeth by direct application 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, 
 
490 DISCOLORED TEETH AND THEIR TREATMENT 
 
 proved inefficient. The gas may be used successfully 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 already described. For this purpose Dr. Kirk's method 
 may be employed conveniently: 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 tightly-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 with a stopping of gutta-percha previously prepared 
 and warmed. A reaction ensues between the boric acid and sodium 
 sulfite whereby sulfur dioxid is liberated, thus : 
 
 2H3BO3 + 3Na2S03 = 2Na3B03 + 3H2O + 3SO2. 
 
 The process is effective in many cases in which the chlorin methods 
 have failed, but is slow in its action, and is largely superseded by the 
 hydrogen dioxid and sodium dioxid methods. 
 
 CATAPHORIC BLEACHING OF TEETH. 
 
 It has been found that aqueous solutions of hydrogen dioxid may be 
 carried into the dentinal structure with great ease by the cataphoric 
 action of the continuous electric current. The appliances necessary 
 for tooth bleaching operations by this means are practically the same 
 as those required in the treatment of hypersensitive dentin. 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 
 twenty-five to thirty volts will be all that is necessary, other cases will 
 require as high as sixty volts to carry 1.5 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 made 
 quickly by shaking together in a test-tube one volume of water 
 and two volumes of 25 per cent, pyrozone. The H2O2 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 
 
CATAPHORIC BLEACHING OF TEETH 491 
 
 sulfate will diminish greatly the resistance of the solution to the 
 passage of the current. 
 
 With the tooth isolated by the rubber dam and having received the 
 treatment preliminary to bleaching, as already described in detail, 
 the aqueous solution of H2O2 is dropped upon cotton in 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 in the tooth. The cotton must at all times be kept wet with the 
 solution. 
 
 The arrangement of the electric terminals with respect to the bleach- 
 ing operation is both theoretically and practically correct as described, 
 namely, the flow of current should be from the anode point through 
 the bleaching solution and tooth and the body of the patient to the 
 cathode. In practice it has been found in some cases which have failed 
 to bleach, with the elements arranged in the series as stated, that upon 
 reversing the poles and direction of current flow the bleaching has 
 followed rapidly. The explanation of this apparent paradox is that 
 by the application in normal order H2O2 was first carried into the tubu- 
 lar structure, and the reversal of the current has acted upon the tubular 
 contents now satiu-ated with the dioxid, and by its propulsive as well 
 as electrolytic effect has removed the pigmentary matter pulpward 
 from the tubuli. Bleaching with reversed poles would be impossible 
 without previous saturation of the dentin by the dioxid solution. 
 
 Dr. M. W. Hollingsworth has devised an ingenious apparatus for 
 cataphoric bleaching which is of special value, as it makes possible the 
 enveloping of the entire tooth with the bleaching fluid, in which it is 
 immersed. The appliance is shown in situ in Fig. 403, and consists 
 of a thin vulcanized caoutchouc bulb shaped like the bulb of a medicine 
 dropper. Through a perforation at its rounded end, made with the 
 ordinary rubber dam punch, the tooth is slipped by mounting the bulb 
 on the applicator (Fig. 404) and 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. 405). Before the electrode is attached the bulb and 
 glass tube are filled with the aqueous pjTozone solution by means of a 
 duplex sjT-inge (Fig. 406), the lower and larger bulb of which exhausts 
 
492 DISCOLORED TEETH AND THEIR TREATMENT 
 
 Fig. 403. — Hollingsworth's device for applying the bleaching agent to the tooth. 
 
 Fig. 404. — Applicator. 
 
 Fig. 405. — Tube electrode. 
 
 Fig. 406. — Duplex syringe. 
 
LIGHT AS AN ADJUVANT TO BLEACHING PROCESS 493 
 
 the contained air in the apparatus and the smaller thumb bulb injects 
 the bleaching solution into the exhausted apparatus. Connection is 
 now made with the source of current as usual, and the bleaching is very 
 rapidly effected. Dr. Hollingsworth recommends the addition of 
 about 1 per cent, of zinc sulfate to the aqueous pjTozone solution, 
 which not only diminishes the resistance 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 satis- 
 factory. 
 
 LIGHT AS AN ADJUVANT TO THE BLEACHING PROCESS. 
 
 If a piece of raw textile fabric is subjected to the simultaneous 
 influence of air, moisture and sunlight, it is bleached. This process 
 is known as natural or Holland bleaching to differentiate it from chemi- 
 cal or artificial bleaching. Most likely, during the process of natural 
 bleaching ozone, O3, is obtained which in tm"n is split up in O2 + O 
 (nascent state). This very slow process may be facilitated materially 
 by utilizing a concentrated solution of hydrogen dioxid in the presence 
 of concentrated artificial light. 
 
 In 1907 Magay^ introduced an improved method of bleaching dis- 
 colored teeth which consisted in applying perhydrol and concentrated 
 sunlight. To overcome the inconvenience of the untrustworthy sun- 
 light, Levy,2 in 1912, substituted artificial light with most gratifying 
 results. 
 
 For a clear understanding of the action of light in this respect, it is 
 probably not amiss to recapitulate briefly the nature of light rays from 
 the physicist's point of view. The solar spectrum fmnishes a band of 
 colors consisting of violet, indigo, blue, green, yellow, orange and red 
 shades, which overlap each other. Beyond either end of the visible 
 spectrum are found a number of rays, the more important ones being 
 known as the electric, and ultra-red rays near the red shade and ultra- 
 violet rays near the violet shade. The rays between the ultra-red and 
 blue division are heat producers and are spoken of as thermic or caloric 
 rays; the rays between the red and violet division are predominant in 
 the production of light and are referred to as luminous or optic rays, 
 while the rays between the red and the tri-ultra-violet division exercise 
 a marked chemical influence on organic and inorganic matter and are 
 known as chemical or actinic rays. The most active actinic rays are 
 those between the blue and ultra-violet division and are known as 
 
 1 Deutsche Monatschrift f. Zahnheilkunde, 1907, p. 65. 
 
 2 Ibid., 1912, p. 138. 
 
494 
 
 DISCOLORED TEETH AND THEIR TREATMENT 
 
 Finsen rays. By interposing either clear or various colored glass lenses 
 in the path of the rays, certain rays are absorbed, as, for instance, red 
 glass obstructs the passage of the light and chemical rays, clear glass 
 absorbs most of the blue and ultra-violet rays (the Finsen rays), blue 
 glass causes a partial absorption of heat rays. In experimenting with 
 the various rays to ascertain their influence on the bleaching process, 
 it has been observed that primarily the heat, and to a less extent the 
 luminous rays, are the principal factors, the actinic rays apparently 
 playing no part therein. The source of light for this purpose may be 
 obtained from any illuminating device. However, a light of very high 
 candle power which can be focussed in the desired direction is to be 
 
 Heaty 
 Rays^ 
 
 
 
 Ultra Red 
 
 
 
 Optic^ 
 Rays^ 
 
 
 Red 
 
 
 
 Orange 
 
 
 Yellow 
 
 
 Green 
 
 
 .Cherr 
 rActiv 
 
 Blue 
 
 
 
 Indigo 
 
 
 Violet 
 
 
 
 Ultra-violet 
 
 ically 
 
 VFi.nsen 
 ' Rays 
 
 Fig. 407. — Diagram of the incomplete spectrum. 
 
 preferred. A tungsten flash light, a dental illuminator, an electric 
 arc lamp or a special bleaching apparatus provided with a suitable 
 reflector and a double convex collecting lens are serviceable. The 
 preparation of the tooth for bleaching by this method is precisely the 
 same as outlined above. The pulp chamber is loosely filled with cotton 
 and a piece of gauze is tied about the tooth and moistened with perhy- 
 drol applied with a medicine dropper. The light is focussed directly 
 upon the exposed tooth and a drop of perhydrol is added from time to 
 time to replace the solution lost by evaporation. In the course of 
 twenty to thirty minutes, the tooth is usually restored to its normal 
 color in such cases as are amenable to the bleaching action of the 
 
SPECIAL DISCOLORATIONS AND THEIR TREATMENT 495 
 
 dioxids. It is always preferable to apply a second treatment after the 
 lapse of a week. 
 
 The bleaching of discolored teeth by the combined utilization of 
 concentrated hydrogen dioxid and light offers most satisfactory results. 
 
 SPECIAL DISCOLORATIONS AND THEIR TREATMENT. 
 
 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 cavity either as food or as medicine may produce discoloration 
 when absorbed by the tooth through the open cavity walls. 
 
 Metallic Salts. — Metallic salts are particularly likely 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 medicaments used in pulp-canal treatment, or even for 
 hjqpersensitive 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 discoloration of this 
 class. It is of the utmost importance to treat these, and much may be 
 accomplished when the causes of the discoloration are known and the 
 proper bleaching method is applied. 
 
 Gold Stains. — Gold stains may arise, as has been indicated, from the 
 injudicious use of gold instruments or failure to remove all gold fillings 
 when applying some of the chlorin methods of bleaching. In the 
 course of time the tooth assumes a pinkish hue, which merges into a 
 characteristic violet or purple, finally becoming black. 
 
 Iron Stains. — 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 used in connection with canal treat- 
 ment. The iron stain is yellowish at first, gradually becoming brown 
 and finally black. 
 
 Copper and Nickel Stains. — 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 chlorophyl green, which eventually becomes 
 black. 
 
 The best general treatment for all of the foregoing stains is to bleach 
 
496 DISCOLORED TEETH AND THEIR TREATMENT 
 
 the tooth by the chlorin method, with observance of the several precau- 
 tions 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 
 per 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 permanent results. 
 
 Silver Stains — Silver stains are comparatively easy to remove, either 
 by an application of the chlorin method or by saturating the tooth with 
 tincture of iodin, thus converting the silver into a chlorid or iodid, as 
 the case may be, after which it may be dissolved out with a saturated 
 solution of ammonia or sodium hyposulfite applied as a bath to the 
 tooth. For this purpose the Hollingsworth bulb dam (see Fig. 403) 
 answers admirably, and although the experiment has not been as yet 
 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. — 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 when 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 solution of potassium iodid. In both cases a final 
 washing with hot distilled water is a sine quo non. 
 
 Manganese Stains. — ^ Manganese stains frequently occur from the use 
 of potassium permanganate, in solution or in substance, in the treat- 
 ment of putrescent canal conditions. The manganese stain is a char- 
 acteristic mahogany brown. It is removed very readily 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 decolorize the stain, after which a liberal treatment 
 of hot distilled water is required as in the foregoing cases. 
 
 Organic Stains — Organic stains are occasionally observed after the 
 use of organic drugs employed in the treatment of infected root canals. 
 Preeminent among these drugs are the essential oils of cassia and to 
 a very much less extent that of cloves. These oils contain furfurol, 
 a colorless pyromucic aldehyd, which readily turns brown on exposure 
 to air and light and stains the tooth structure a tan color. These 
 pigments are removed readily by any one of the dioxid bleaching 
 methods. 
 
 Superficial organic stains from foodstuffs, especially fruits, such as 
 blueberries, black cherries, etc., from the use of tobacco or from chewing 
 
SPECIAL DISCOLORATION S AND THEIR TREATMENT 497 
 
 betel nuts and the green discolorations upon the teeth of children 
 (growth of various molds and fungi upon Nasmyth's membrane and 
 formation of sulfomet hemoglobin) and occasionally from colored 
 dentifrices, are usually removed readily by employing a fine abrasive 
 (pumice stone) mixed into a paste with hydrogen dioxid. In tobacco 
 and betel nut stains alcohol mixed with pumice stone powder is to be 
 preferred. 
 
 In bygone days it was customary with the married women of Japan 
 to blacken their teeth with a concoction known as ''Okaguro" or 
 *'Kane" and which is said to be composed of urine, iron filings and sake. 
 The stain produced by this caustic fluid is more or less permanent. 
 At present, this custom has fallen largely into disuse. 
 
 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 noted 
 carefully, and treatment 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 special reference to the character 
 of the discoloration and applied with due care to its details in order 
 that the chemical requirements of the operation may be met intelli- 
 gently, without which care success is impossible. 
 
 32 
 
CHAPTER XII. 
 
 LOCAL ANESTHESIA. 
 
 By HERMANN PRINZ, M.D., D.D.S. 
 
 Local anesthetics are agents which are employed for the purpose of 
 producing insensibility to pain in a circumscribed area of tissue. 
 
 History. — ^From an historical viewpoint, comparatively few important 
 facts are to be recorded prior to the introduction of cocain for the pur- 
 pose of obtunding pain locally. The compression of nerve trunks for 
 the abolition of pain seems to be of an old and unknown origin, which 
 was revived by Guy du Chauliac and Ambroise Pare, and indirectly 
 found a permanent place in surgery as the Esmarch elastic bandage. 
 Physically reducing the temperature of a part of the body by the appli- 
 cation of cold was instituted much later. Bartholin and Severino 
 introduced this method in the middle of the sixteenth century. It 
 became a lost art, however, until John Hunter, of London, again called 
 attention to its benefits by demonstrating it upon animals, and Larrey, 
 the chief surgeon of Napoleon's army, employed it for amputations in 
 1807. Through the efforts of Sir B. W. Richardson, in 1866, it was 
 placed upon a rational basis by the introduction of the ether spray. 
 The various narcotics which were employed for internal purposes were 
 also made use of as local applications. Mandragora, henbane, aconite, 
 the juice of the poppyhead, and many other analgesic drugs enjoyed 
 a world-wide reputation. The empirical search for new methods and 
 means pressed the mysticism of the electric current into service, open- 
 ing a prolific field to the charlatan which even to this day has not lost 
 its charm. Richardson's voltaic narcotism for a time attracted the 
 attention of the medical profession; and Francis, in 1858, recommended 
 the attachment of the electric current to the handles of the forceps for 
 the painless extraction of the teeth, and as dental markets still contain 
 appliances of this nature for sale, it seems that the method is still in 
 vogue with some operators. In the early days of modern dentistry 
 we met with many feeble efforts to alleviate pain during trying oper- 
 ations. Chloroform, alcohol, ether, aconite, opium, the essential oils, 
 and many other drugs were the usual means employed, either simply 
 
 (498) 
 
MEANS OF PRODUCING LOCAL ANESTHESIA 499 
 
 or as compounds, usually under fanciful names, for such purposes. 
 Snape's calorific fluid, composed of chloroform, tincture of lemon 
 balm, and oil of cloves; nabolis, consisting of glycerite of tannic acid 
 and a small quantity of chloral hydrate; Morton's letheon, which was 
 sulphuric ether mixed with aromatic oils, are examples of proprietary 
 preparations which enjoyed quite a reputation in their time. 
 
 In 1844 F. Rynd, an Irish surgeon, introduced a method of general 
 medication by means of hypodermic injections which, in 1853, was 
 much improved by Alexander Wood, of Edinburgh. It was suggested 
 at once that such drugs as morphia or tincture of opium be employed 
 for the purpose of producing local anesthesia. The results were not 
 encouraging, however, until Koller, in 1884, advocated cocain. With 
 the introduction of this drug into therapeutics, local anesthesia achieved 
 results which were beyond expectations, and its adoption created a 
 new erajn local anesthesia. 
 
 Means of Producing Local Anesthesia. ^ — The term anesthesia (without 
 sensation), which was suggested to Dr. Morton in 1846 by that great 
 physician-litterateur, Oliver Wendell Holmes, is usually defined as an 
 artificial deprivation of all sensation, while the mere absence of pain is 
 referred to as analgesia. Correctly speaking, the term local anes- 
 thesia is partially a misnomer. In producing local anesthesia we do 
 not fully comply with all the requirements that anesthesia demands, 
 because a part of the sensorium — the sense of touch, for instance — is 
 not abolished. The term local anesthesia has, however, acquired 
 such universal recognition that it would seem unwise to recommend a 
 change. 
 
 Anesthesia may be produced artificially by inhibiting the sensory 
 nerve fibers at their central end-organs in the brain or at their peri- 
 pheral end-organs in the tissues, thus producing general and local 
 anesthesia. Local anesthesia may be obtained in two definite ways: 
 we may inhibit the function of the peripheral nerves in a circum- 
 scribed area of tissue, and refer to this process as terminal anesthesia; 
 or, we may block the conductivity of a sensory nerve trunk somewhere 
 between the brain and periphery, and speak of it as conduction anes- 
 thesia. Dental terminal anesthesia is usually produced by a sub- 
 periosteal injection (indirect anesthetization) or a peridental injection 
 (direct anesthetization), while conduction anesthesia may be pro- 
 duced by injecting into the nerve trunk proper — endoneiu"al injection — 
 or by injecting into the tissues siu-rounding a nerve trunk— perineural 
 injection. The latter form is the usual method pursued when conduc- 
 tion anesthesia for dental purposes is indicated. 
 
500 LOCAL ANESTHESIA 
 
 LOCAL ANESTHESIA. 
 
 Terminal anesthesia Conduction anesthesia 
 
 Subperiosteal Peridental Endoneural Perineural 
 
 injection injection injection injection 
 
 The successful practice of local anesthesia involves the carefully 
 adjusted cooperation of a number of important details, each one 
 constituting a definite feature in itself, which, when neglected, must 
 necessarily result in failure. The more important details follow: 
 
 1. A sterile solution of drugs possessing active anesthetic potencies 
 and which, in their composition, must correspond to the physical and 
 physiologic laws which govern certain functions of the living cells. 
 
 2. A carefully selected sterile hypodermic armamentarium. 
 
 3. A complete mastery of the technic. 
 
 4. A proper selection of the correct methods of injection suitable for 
 the case in hand. 
 
 5. Suitable preparation of the site of injection. 
 
 6. The complete cooperation of the patient. 
 
 7. Good judgment of prevailing conditions. 
 
 PHYSIOLOGIC ACTION OF ANESTHETICS. 
 
 According to more recent therapeutic conceptions, it is generally 
 recognized that a drug or combination of drugs which simultaneously 
 produces local anemia and inhibition of the functions of the sensory 
 nerves in a circumscribed area of tissue is the logical solution of the 
 question of local anesthesia. Certain important factors, however, 
 relative to the physiologic and physical action of the solution employed 
 for hypodermic injection upon the cell, govern the successful appli- 
 cation of such methods. It is of prime importance, therefore, to 
 comply with the laws regulating the absorption of injected solutions, 
 namely, osmotic pressure. 
 
 If we separate two solutions of salt of different concentration by a 
 permeable membrane, a continuous current of salt and water through 
 the membrane results, which ceases only after equalization of the den- 
 sity of the two liquids, namely, when equal osmotic pressure, according 
 to the Boyle — ^Van't Hoff's Law — is established. The current passes 
 in both directions, drawing salt from the stronger to the weaker solu- 
 tion and water, vice versa, until osmotic equilibrium is obtained. The 
 
PIIYSIOLOaiC ACTION OF ANESTHETICS .jlJl 
 
 resultant solutions are termed isotonic (I)e Vries). Osmotic pressure 
 is a physical phenomenon which is possessed by water and all aqueous 
 solutions; it is dependent upon the number of molecules of salt present 
 in the solution and upon their power of dissociation. In organized 
 nature these osmotic interchanges are an important factor in regu- 
 lating the tissue fluids of both animals and plants. In the animal 
 tissue the circulation depends principally upon the mechanical force 
 exerted by the heart. The life of the cell depends upon the continuous 
 passage of the fluids which furnish the nutrient materials, consisting of 
 water, salts and albumin. These chemicals are normally present in 
 certain definite proportions. The membrane of the living cell is, 
 however, only semi-permeable, namely, the cell readily absorbs dis- 
 tilled water when surrounded therewith; it becomes macerated, 
 loses its normal structure and finally dies. If, on the other hand, the 
 siuTounding fluid be a highly concentrated salt solution, the solution 
 absorbs water from the cell; no salt molecules enter the cell body proper. 
 The cell shrinks and finally dies. This process of cell death in general 
 pathology is referred to as necrobiosis. 
 
 A further important factor teaches us that all aqueous solutions 
 which are isotonic possess the same freezing point, namely, all solutions 
 possessing an equal freezing point are equimolecular and possess 
 equal osmotic pressure. This law of physical chemistry has materially 
 simplified the preparation of such solutions. The freezing point of 
 human blood, lymph, serum, etc., has been found to equal, approxi- 
 mately, 0.55° C, which in turn corresponds to a 0.85 per cent, sodium 
 chlorid solution. Such a solution is termed a physiologic salt solution. 
 In the older works on physiology a 0.6 per cent, sodium chlorid solu- 
 tion is referred to as a physiologic salt solution; this solution corre- 
 sponds to the density of the blood of a frog. A slight deviation above 
 and below the normal percentage of the solid constituents is per- 
 missible. When physiologic salt solution at body temperature is 
 injected into the loose connective-tissue under the skin in moderate 
 quantities, neither swelling nor shrinkage of the cells as such occurs; 
 a simple wheal is formed which soon disappears; therefore no irri- 
 tation results, and no pain is felt. Similar bodies which are equally 
 soluble in water act in the same manner, with the exception of the 
 salts of the alkali and earth metals, such as potassium or sodium bromid. 
 The latter substances produce intense physical irritation, followed by 
 prolonged anesthesia, and consequently, are termed by Liebreich 
 "painful anesthetics." If, on the other hand, simple distilled w^ater 
 be injected, a superficial anesthesia only is produced; the injection 
 itself is very painful and acts as a direct protoplasm poison by macer- 
 ating the cell contents and resulting in severe damage or even death 
 
502 LOCAL ANESTHESIA 
 
 of the cell. If distilled water approximately at the ratio of 10 drams 
 to the pomid of body weight be injected into dogs, they will succumb 
 in a short time. The injection of higher concentrated salt solution 
 produces opposite effects; water is removed from the cells with more 
 or less pronounced pain, followed by superficial anesthesia. The red 
 corpuscles are extremely susceptible to any injected fluid which is not 
 isotonic in its nature. They are destroyed (hemolysis) by the injection 
 of fluids which are not represented by an isotonic salt solution. Hypo- 
 tonic solutions cause swelling of the tissues, while h^-pertonic solutions 
 produce shrinkage. These manifestations are proportionately the 
 more intense the further the solution is removed from the freezing point 
 of the blood. Furthermore, hypotonic solutions as well as hypertonic 
 solutions, require much more time for their absorption than isotonic 
 solutions; the osmotic pressure must be standardized to the surround- 
 ing tissue fluids. 
 
 Local anemia prevents the rapid absorption of fluids that are 
 injected into the affected area. Retarded absorption means increased 
 action and consumption of the injected drug and, as a consequence," 
 less danger from general absorption. 
 
 The more important means to produce local anemia are: (1) the 
 Esmarch elastic bandage; (2) the application of cold, and (3) the 
 extract of the suprarenal capsule. 
 
 Some observers have maintained that local anemia produces anes- 
 thesia. This, however,, is not the case; it is merely an important means 
 of confining the injected anesthetic to the anemic region, and thus 
 bringing about an increased and prolonged action of the drug. Con- 
 sequently, the concentration of the anesthetic solution may be of a 
 lower percentage, which, of course, lessens the danger of intoxication. 
 For plausible reasons the Esmarch elastic bandage cannot be made 
 use of for dental operations. 
 
 Physically reducing the temperature of the body by the application 
 of cold (ice pack, ice and salt mixture, cold, metals, etc.), was practiced 
 by the older surgeons. Arnott in 1849 and Blundell in 1855 advocated 
 ice packs for the painless extraction of teeth. Through the efforts of 
 Sir B. W. Richardson, in 1866, this method was placed on a rational 
 basis by the introduction of the ether spray. To obtain good results, 
 a pure ether (boiling point 95° F., 35° C.) free from water is necessary. 
 Certain other volatile hydrocarbons possess similar properties in vary- 
 ing degrees, depending upon their individual boiling point. In 1867 
 Rottenstein called attention to the use of ethyl chlorid as a refrigerating 
 agent, and Rhein, in 1889, introduced methyl chlorid for the same 
 purpose. In 1891, Redard reintroduced ethyl chlorid as a local anes- 
 thetic, which since has become known by many trade names — as 
 
ETHYL CHLORID AND ITS ADMINISTRATION 503 
 
 antidolorine, kelene, narcotile, etc. Mixtures of the first two in 
 various proportions known as anestol, anestile, coryl, metethyl, etc., 
 are extensively used in minor oral and general surgery. A pure ethyl 
 chlorid (boiling point 55° F., 13° C.) is best suited for this purpose, 
 as it lowers the temperature of the tissues sufficiently to produce a 
 short superficial anesthesia in a few minutes. Too rapid cooling or pro- 
 longed freezing by methyl chlorid (boiling point, —12° F., —24.5° C.) 
 or the various mixtures thereof, produces deeper anesthesia. Such 
 procedures are dangerous because they frequently cut off circulation 
 in the affected part so completely as to produce sloughing (necrosis) . 
 Liquid nitrous oxid, liquid or solid carbon dioxid (recently known as 
 carbonic acid snow), and liquid air, all of which have a boiling point 
 far below zero, are recommended for similar purposes, but they require 
 cumbersome apparatus and are extremely dangerous. 
 
 Fig. 408. — Ethyl chlorid spray tube. (Metal.) 
 
 ETHYL CHLORID AND ITS ADMINISTRATION. 
 
 Ethyl chlorid (monochlorethane; hydrochloric ether; C2H5CI). "A 
 haloid derivative, prepared by the action of hydrochloric acid gas 
 on absolute alcohol." At normal temperature, ethyl chlorid is a gas 
 and under a pressure of two atmospheres it condenses to a colorless, 
 mobile, very volatile liquid, having a characteristic, rather agreeable 
 odor, and burning taste. It boils at about 55° F. (13° C.) and is very 
 inflammable, burning w4th a smoky, green-edged flame. It is stored 
 in sealed glass or metal tubes, and when liberated at ordinary room 
 temperature, 70° F. (21° C.) evaporates at once. In commerce it is 
 supplied in plain or graduated tubes of from 30 to 60 grams capacity, 
 or stored in metallic cylinders holding from 60 to 100 grams or more. 
 To remove the ethyl chlorid from the hermetically sealed small tubes, 
 the neck must be broken off, while the larger glass and metallic tubes 
 are provided with suitable stopcocks of various designs to allow definite 
 amounts of the liquid to be released. 
 
 Mode of Application. — ^For the extraction of teeth, immediate removal 
 of the pulp, opening of abscesses and other minor operations about the 
 
504 LOCAL ANESTHESIA 
 
 oral cavity, the tube should be warmed to body temperature by placing 
 it in heated water, and its capillary end should be held about six to 
 ten inches from the field of operation. The distance depends upon the 
 size of the orifice of the nozzle. Complete vaporization should always 
 be produced. The Gebauer tube is fitted with a spray nozzle, which 
 shortens the distance one to two inches, and is especially well adapted 
 for dental purposes. The stream is directed upon the tissues until 
 the latter are covered with ice crystals and have turned white. For 
 the extraction of teeth, the liquid should be projected directly upon the 
 surface of the gum, as near to the apex of the root as possible, but care 
 should be taken to protect the crown of the tooth on account of the 
 painful action of cold on this part. The tissues to be anesthetized 
 should first be dried and well surrounded by a film of vaselin or glycerin, 
 and protected by cotton rolls and napkins, to prevent the liquid from 
 running into the throat. Let the patient breathe through the nose. 
 Occasionally light forms of general anesthesia are induced by inhaling 
 the vapor. On account of the difficulty of directing the stream of 
 ethyl chlorid upon the tissue in the posterior parts of the mouth, it is 
 not successfully applied to those regions. The intense pain produced 
 by the extreme cold prohibits its use in acute pulpitis and in peri- 
 cementitis. To anesthetize the second and third branches of the 
 fifth nerve, it is recommended that the stream of ethyl chlorid 
 be directed upon the cheek in front of the tragus of the ear, but the 
 author has not seen any good results from such a procedure. Caution 
 should be exercised in using ethyl chlorid near an open flame or in 
 conjunction with the thermocautery, as severe burns have resulted by 
 setting the inflammable vapor on fire. 
 
 THE ACTIVE PRINCIPLE OF THE SUPRARENAL CAPSULE AND ITS 
 SYNTHETIC SUBSTITUTES. 
 
 Within the last decade the active principle of the suprarenal capsule 
 has evoked extensive comments in therapeutic literature. It has been 
 isolated by a number of investigators under different names, as epi- 
 nephrin by Abel, suprarenin by Fuerth, and adrenalin by Takamine 
 and Aldrich. Many other titles are given to this chemical, as adneph- 
 rin, paranephrin, suprarenalin, supracapsulin, hemostasin, etc. Epi- 
 nephrin is a grayish-white powder, slightly alkaline in reaction, and 
 perfectly stable in dry form. It is sparingly soluble in cold and more 
 soluble in hot water, is insoluble in ether or alcohol, and with acids it 
 readily forms soluble salts. The preparation that is employed mostly 
 for therapeutic purposes is a solution of epinephrin hydrochlorid in a 
 1 to 1000 physiologic salt solution, to which preservatives, as small 
 
ACTIVE PRINCIPLE OF THE SUPRARENAL CAPSULE 505 
 
 quantities of chloretoiie, tlixinol, etc., are added. Alkali of any kind 
 is especially destructive to this sensitive alkaloid; even the small 
 quantities of free alkali present in ordinary glass are dangerous. 
 Bottles intended for storing epinephrin solutions should be made of 
 amber-colored alkali-free or Jena glass or bottles of ordinary glass 
 should be immersed in a diluted solution of hydrochloric acid for a 
 few days and then thoroughly washed in running water before they 
 are used. Epinephrin solution does not keep well. On exposure to 
 the air or light it is easily decomposed, becoming pink, then red, and 
 finally brown, and with this change of color its physiologic property is 
 destroyed. If the epinephrin solution be further diluted, it becomes 
 practically worthless within a few days. 
 
 When epinephrin is injected into the tissues, even in extremely small 
 doses, it temporarily raises the arterial blood-pressure, acting as a 
 powerful vasoconstrictor by stimulating the smooth muscular coat of 
 the bloodvessels, and thus produces local anemia. Large doses finally 
 reduce the blood-pressure, and heart failure results. The respiration 
 at first quickly increases, but slows down and finally stops with expir- 
 ation. Its action is largely confined to the smooth muscle fibers of the 
 peripheral vessels. Epinephrin is destroyed by the living tissue cells, 
 the body ridding itself of the poison in some unknown manner. While 
 epinephrin does not possess local anesthetic action, it increases very 
 markedly the effect of certain anesthetics when combined with them. 
 These observations are of vast importance in connection with the pro- 
 duction of local anesthesia. Carpenter, Peters, Moller, and others 
 referred to the use of epinephrin in this respect, and finally Braun, in 
 1902, published his classic researches, and to him and his co-workers, 
 especially Heinze and Laewen, belongs the credit of establishing a 
 rational basis for the production of local anesthesia. It is claimed that 
 secondary hemorrhage frequently occurs after the anemia produced by 
 the epinephrin has subsided, and that the tissues themselves suffer 
 from the poisoning effect of the drug, resulting in necrosis. Such 
 results are produced only by the injection of too large quantities, w^hich, 
 by their deeper action, close up the larger capillaries. The prolonged 
 anemia will give way to a dilation of the bloodvessels, and if the tissues 
 are too long deprived of the circulation, we are able to miderstand 
 why sloughing may result. Small doses of epinephrin have no effect 
 upon the tissues or on the healing of a wound. Palpitation of the 
 heart and muscular tremor, which were occasionally noticed in the 
 early period of th-e use of the drug, are the direct result of too large 
 doses. Recently a synthetic epinephrin has been successfully pre- 
 pared by Stolz, which, with hydrochloric acid, forms a stable and 
 readily soluble salt. It is known as synthetic suprarenin hydrochlorid. 
 
506 LOCAL ANESTHESIA 
 
 The new chemical has been carefully tested physiologically and in 
 clinical work, and the consensus of opinion points to the fact that it is 
 not only equal, but in certain respects superior, to the organic prepara- 
 tions. Synthetic suprarenin solutions may be sterilized readily by boiling. 
 They are relatively stable, and their chemical purity insures uniform 
 results. They are comparatively free from dangerous side actions. 
 The author's observations regarding the value of synthetic suprarenin 
 relative to its general behavior are in full accordance with the above 
 statements,, and its advantage over the organic preparations has led 
 him to adopt it as a component in the preparation of local anesthetic 
 solutions. For dental purposes, that is for injecting into the gum 
 tissue, the dose may be limited to one drop of the epinephrin solution 
 (1 to 1000) or the synthetic suprarenin solution (1 to 1000) added to 
 each cubic centimeter of the anesthetic solution, 5 drops being approxi- 
 mately the maximum dose to be injected at one time. 
 
 The dosage of the relative amounts of epinephrin solution may be 
 arranged as follows: 
 
 Add 1 drop of epinephrin to 1 c.c. of the novocain solution. 
 
 Add 2 drops of epinephrin to 3 c.c. of the novocain solution. 
 
 Add 3 drops of epinephrin to 5 c.c. of the novocain solution. 
 
 Add 4 drops of epinephrin to 8 c.c. of the novocain solution. 
 
 Add 5 drops of epinephrin to 10 or more c.c. of the novocain solution. 
 
 THE LOCAL ANESTHETICS. 
 
 Cocain. — Cocain, when injected into the tissues, produces typical 
 local and general effects. Locally, it possesses a definite affinity for 
 the peripheral nerves; it causes constriction of the smaller arteries, 
 producing slight anemia in the injected area with diminished action 
 of the leukocytes. However, different parts of the organism require 
 different doses to bring about the same reaction. Upon mucous sur- 
 faces, paralysis of the sensory nerves is produced; the senses of touch 
 and smell are temporarily inhibited. The blood and the circulation 
 suffer little. If cocain in sufficient quantities be absorbed by the 
 circulation, general manifestations are produced from bringing other 
 tissues in close contact with the poison. The principal disturbances 
 of the central nervous system make themselves known by vertigo, a 
 very soft pulse, enlarged and staring pupils, and difficult respiration. 
 Vomiting may occur; the throat feels dry; intense excitement is 
 followed by epileptiform spasms; finally complete loss of sensation and 
 motility results, which terminates in death from cessation of respiration. 
 The general character of the disturbances is closely related to that 
 which occurs in chloroform or ether poisoning. The typical picture of 
 
LOCAL ANESTHETICS . 507 
 
 cocain poisoning is produced when the blood flowing through the 
 central nervous system contains a sufficient quantity of the drug, 
 even for a moment only, which is dangerous to this organ. No 
 maximum dose can be positively established. This is equally true of 
 chloroform and ether when used for general anesthetic purposes. The 
 many cases of so-called idiosyncrasy probably find an explanation in 
 the too large doses which formerly were administered so frequently. 
 
 With our increased knowledge of the action of cocain upon the 
 tissues and a proper technic of the injection, dangerous results are 
 comparatively rare at present. No direct antidotes are known; the 
 treatment of general intoxication is purely symptomatic. Anemia of 
 the brain, which is of little consequence, may be overcome readily by 
 placing the patient in a recumbent position or by complete inversion, 
 if necessary. As a powerful dilator of the peripheral vessels the vapors 
 of amyl nitrite are exceedingly useful ; it is best administered by placing 
 3 to 5 drops of the fluid upon a napkin and holding it before the nostrils 
 for inhalation. Flushing of the face and an increase in the frequency 
 of the pulse follow almost momentarily. For convenience, amyl 
 nitrite may be procured in small glass capsules, holding the necessary 
 quantity for one inhalation. Nausea may be remedied by administer- 
 ing small doses of spirits of peppermint, aromatic spirits of ammonia, 
 etc. To overcome the disturbances of respiration^ quickly instituted 
 artificial respiration is the alpha and omega of all methods of resusci- 
 tation. In cases of shock, Mumford recommends the hypodermic 
 injection of morphin. Engstadt lauds very highly the administration 
 of ether for such purposes and claims that it is the antidote for cocain 
 and novocain. To obtain the best results, the ether should be admin- 
 istered upon a mask by the drop method and only to the degree of 
 mild surgical analgesia. 
 
 The relative toxicity of a given quantity of cocain solution depends 
 upon the concentration of its solution. Reclus and others have clearly 
 demonstrated that a fixed quantity of cocain in a 5 per cent, solution 
 is almost equally as poisonous as five times the same quantity in a 
 I per cent, solution. From the extensive literature on the subject, 
 we are safe in fixing the strength of the solution for dental purposes 
 at 1 per cent. This quantity of cocain raises the freezing point of dis- 
 tilled water just a little above 0.1° C. To obtain an isotonic solution 
 corresponding to the freezing point of the blood, 0.8 per cent, of sodium 
 chlorid must be added. Having thus prepared a cocain solution which 
 is equal to the blood in its osmotic pressure upon the cell wall, it is 
 necessary to aid the slightly vasoconstrictor power of the drug by the 
 addition of a moderate quantity of epinephrin, thus increasing the 
 confinement of the solution to the injected area by producing a deeper 
 
508 . LOCAL ANESTHESIA 
 
 anemia, for a two-fold purpose: (1) to act as a means of increasing 
 the anesthetic effect of cocain, and (2) to lessen its toxicity upon the 
 general system by slower absorption. As stated above, 1 drop of 
 epinephrin solution added to 1 c.c. of the isotonic cocain solution is 
 sufficient to produce the desired effect. 
 
 A suitable solution for dental purposes may be prepared as follows: 
 
 Cocain hydrochloric! 5 gr. (0.30 gm.) 
 
 Sodium chlorid 4 gr. ( 0.25 gm.) 
 
 Sterile water 1 fl. oz. (30.00 c.c.) 
 
 To each syringeful (2 c.c.) add one drop of epinephrin chlorid solu- 
 tion when used. 
 
 Ready-made cocain solutions are sterilized with difficulty and will 
 not keep when frequently exposed to the air. Ready-made anesthetic 
 solutions as found in the market usually contain preservatives, such 
 as phenol, naphthol, boric acid, iodin, essential oils, alcohol, etc., in 
 variable quantities. Some of these solutions have a distinct acid 
 reaction. While they may produce a serviceable degree of anesthesia; 
 they usually damage the injected tissues sufficiently to retard the 
 normal process of wound healing. 
 
 Substitutes of Cocain. — ^Ever since the introduction of cocain into 
 materia medica for the purpose of producing local anesthesia, quite a 
 number of substitutes have been placed before the profession, for which 
 superiority in one respect or another is claimed over the original 
 cocain. The more prominent members of this group are tropacocain, 
 the eucains, acoin, nirvanin, alypin, stovain, novocain, quinin and 
 urea hydrochlorid. None of these compounds, with the exception of 
 novocain, now also known as procain, has proved satisfactory for the 
 purpose in view. The classical researches of Braun have established 
 certain facts which are essential to the value of a local anesthetic. 
 These facts concern their relationship to the tissues in regard to their 
 toxicity, irritation, solubility and penetration, and to the toleration 
 of epinephrin. 
 
 It is not necessary to enter into a discussion of the pharmacologic 
 action of the drugs usually classified as local anesthetics. Let it suffice 
 to state how the above mentioned drugs fulfil the demands of Braun. 
 Tropacocain is less poisonous, but also less active than cocain, and 
 completely destroys the action of epinephrin; the eucains partially 
 destroy the epinephrin action, and are, comparatively speaking, 
 equally as poisonous as cocain; acoin is irritating to the tissues and 
 more poisonous than cocain; nirvanin possesses little anesthetic value; 
 alypin and stovain are closely related. Both are slightly acid in 
 reaction, produce pain when injected, and occasionally necrosis. 
 
LOCAL ANESTHETICS 509 
 
 According to Le Brocq, the toxicity of these chemicals may be 
 expressed as follows : if the toxicity of cocain is taken as the standard 
 and expressed as 1, then that of alypin will represent 1.25; nirvanin, 
 0.714; stovain, 0.625; tropacocain, 0.5; novocain, 0.49; eucain B, 0.414. 
 
 Novocain alone fully corresponds to every one of the above claims. 
 Its toxicity is about six times less than cocain; it does not irritate 
 in the slightest degree when injected, consequently no pain is felt 
 from its injection 2^^^ se; it is soluble in its own weight of water; it 
 will combine with epinephrin in any proportion without interfering 
 with the physiologic action of the latter, and it will be absorbed readily 
 by the mucous membrane. The studies of Biberfield and Braun 
 brought to light another extremely interesting fact concerning the 
 novocain-epinephrin combination. Both experimenters, working inde- 
 pendently of each other, observed that epinephrin anemia on the one 
 hand, and the novocain anesthesia on the other hand were markedly 
 increased in their total effects upon the tissues. Consequently, a 
 smaller quantity of this most happy combination is required to pro- 
 duce the same therapeutic effect as a large dose of each individual 
 drug would produce when injected separately. 
 
 Novocain. — Novocain (procain) is the hydrochloric salt of a syn- 
 thetically prepared alkaloid, the methyl ester of a p-amino-benzoic 
 acid. It is a white crystalline powder melting at 263° F, (150° C). 
 It may be heated to 200° F. (120° C.) without decomposition. It dis- 
 solves in an equal amount of cold water, the solution having a neutral 
 character; in cold alcohol it dissolves in the proportion of 1 to 30. 
 Caustic alkalies and alkaline carbonates precipitate the free base from 
 the aqueous solution in the form of a colorless oil, which soon solidifies. 
 It is incompatible with the alkalies and alkaline carbonates, with picric 
 acid and the iodids. Its solutions may be sterilized by boiling without 
 decomposition. 
 
 As stated above, the relative toxicity of a given quantity of cocain 
 in solution depends upon its concentration; this same peculiarity is 
 not shared by novocain. The dose of novocain may be fixed safely at 
 one-third of a grain for a single injection. For dental purposes a 1| 
 or 2 per cent, solution in combination with epinephrin has been injected 
 without any ill results. On account of its pow^erful vasoconstrictor 
 action, the addition of epinephrin in small doses is well suited to the 
 purpose of confining the injected novocain to a given area. It is the 
 important factor which prevents the ready absorption of both drugs, 
 and consequently largely nullifies poisonous results. An injection of 
 10 drops of a 2 per cent, solution of novocain labially into the tissue 
 produces a diffuse anesthesia lasting approximately twenty minutes; 
 the same quantity, with the addition of one drop of epinephrin 
 
510 
 
 LOCAL ANESTHESIA 
 
 chlorid solution, increases the anesthetic period to over one hour, and 
 locaHzes the effect upon the injected area. 
 
 A suitable solution of novocain for dental purposes may be prepared 
 as follows: 
 
 Novocain 10 gr. (0.60 gm.) 
 
 Sodium chlorid 4 gr. (0.25 gm.) 
 
 Distilled water 1 fl. oz. (30.00 c.c.) 
 
 Boil. 
 
 To each cubic centimeter add one drop of epinephrin solution when used. 
 
 A sterile solution may be made extemporaneously by dissolving the 
 necessary amount of novocain-epinephrin in tablet form in a given 
 quantity of boiling physiologic salt solution. A suitable tablet may be 
 prepared as follows: 
 
 Novocain .... 
 Suprarenin hydrochlorid 
 
 gr. 
 
 (0.015 gm.) 
 (0.000054 gm.) 
 
 One tablet dissolved in 20 minims (1 c.c.) of boiling physiologic salt 
 solution makes a 1| per cent, solution of novocain ready for imme- 
 diate use. 
 
 Solutions for hypodermic purposes should be made fresh when 
 needed. A simple porcelain crucible or a graduated porcelain dissolv- 
 ing cup held by a suitable twisted aluminum 
 tongue and a dropping bottle constitute a 
 simple outfit for this work. The dropping 
 bottle should hold about 4 ounces and should 
 be provided with a dust cap. A groove on one 
 side of the neck of the bottle, and a vent on the 
 other connected with two grooves in the back of 
 the stopper allow the contents to flow drop by 
 drop. A quarter turn of the stopper closes 
 the bottle tightly. The number of drops pres- 
 ent in each cubic centimeter differs with the 
 various sizes of the dropping bottle, hence each 
 bottle has to be standardized with a tested 
 minim graduate or a tested burette. The 
 standardized number may be marked on the 
 respective bottles with a carborundum stone. 
 
 Hypodermic Armamentarium.^ — A hypodermic 
 s;yTinge that answers all dental purposes equally 
 well is an important factor in carrying out the 
 correct technic of the injection. The injection 
 into the dense gum tissue often requires 10 or 
 more pounds of pressure as registered by an 
 interposed dynamometer, while in pressure anesthesia even greater 
 pressure is frequently applied. 
 
 Fig. 409. — Dropping 
 bottle. 
 
LOCAL ANESTHETICS 511 
 
 The selection of a suitable hypodermic syringe is largely a matter 
 of choice. All-glass syringes, glass-barrel syringes, and all-metal 
 syringes are the usual types found in the market. An all-glass syringe 
 that answers every reasonable demand regarding asepsis, durability, 
 and perfect construction, and that is giving universal satisfaction, has 
 been brought out recently by the S. S. White Dental Manufacturing 
 Company. The syringe is constructed after the well known Luer 
 pattern, holding 1^ c.c. and it is marked with suitable divisions on the 
 barrel. The piston and the barrel are ground so perfectly that no 
 washers are required to make water-tight joints. An adjustable finger 
 rest is easily slipped over the assembled parts which greatly assists in 
 adjusting the needle-opening in any desired direction and in exerting 
 pressure on the piston. The piston-rod, made of solid glass, is suffi- 
 ciently long to allow about two inches of space between the finger rest 
 and the piston top. This space is of importance, as it allows the last 
 drop of fluid to be expelled under pressure without tiring the fingers. 
 A removable cane-handle, made of metal, greatly facilitates the exer- 
 tion of pressure on the piston. The needle-adapter carries a universal 
 thread so as to accommodate the hub of the ordinary hypodermic 
 needles. The various parts of the syringe may be detached in a few 
 moments to allow sterilization by boiling. 
 
 Glass-barrel syringes are not to be recommended for dental purposes, 
 as they are too troublesome to keep in order. After carefully testing 
 most of the metal hypodermic syringes offered in the markets within 
 the last ten years, by means of the pressure gauge and in clinical work 
 subjecting them to a routine wear, the author has found that the 
 syringes of the so-called "Imperial" type are to be preferred over other 
 makes. They are usually made of nickel-plated brass which, however, 
 is a disadvantage, as the nickel quickly wears off from the piston, and 
 exposes easily corroded brass. The piston should preferably be made 
 of pure German silver. An all-metal syringe as pictured in Fig. 410 
 gives good results in heavy pressure work and can be recommended. 
 The syringe holds 40 minims (2 c.c), is provided with a strong finger 
 crossbar, and is extremely simple in construction. The piston consists 
 of a plain metal rod, without a thickened or ground piston-end or 
 packing. The packing consists of leather washers inserted at the 
 screw-joint, and is quickly removed and replaced if necessary. 
 
 The hypodermic syringe requires careful attention. It is not neces- 
 sary to sterilize it by boiling after each use, unless it should be con- 
 taminated with blood or pus. The simple repeated washings with a 
 mixture of one part of glycerin and seven parts of alcohol and careful 
 drying are sufficient. The cap should be readjusted,, and the piston 
 rod covered with a thin carbolated vaselin or sm-gical lubricating jelly 
 
512 
 
 LOCAL ANESTHESIA 
 
 and placed in position. If the syringe be boiled, all the washers must 
 be removed. The syringe is best kept in a covered glass or metal case; 
 a large bacteriologic Petri dish is suitable for this purpose. Leather- 
 lined or felt-lined boxes afford breeding places for bacteria, and should 
 
 Fig. 410. — Metal syringe. 
 
 not be used. Some operators prefer to keep their syringes constantly 
 in the above mentioned glycerin-alcohol solution when not in use, and 
 others prefer to place them in a special sterilizing jar which may now 
 be purchased in the market. 
 
LOCAL ANESTHETICS 
 
 513 
 
 Dental h>']Dodermic needles should be made preferably of seamless 
 steel, or still better, of vanadimn steel, 24 to 26 B and S gauge and 
 proA'ided with a short razor edge point. Thicker needles cause unneces- 
 sary pain, and thinner needles are liable to break. Iridio-platinum 
 needles are preferred by some operators, as they may be readily steril- 
 ized in an open flame. The needle should measure from a half to one 
 inch. For infiltration or conduction anesthesia one and a half -inch 
 
 Fig. 411. — Hood's sterilizing jar. 
 
 needles are necessary and cm'ved attachments of various shapes are 
 essential in reachmg the posterior parts of the mouth. The "Schim- 
 mel"" needles are excellent, but do not fit every syringe. For pressure 
 anesthesia special needles are required, and may be bought or quickly 
 prepared by grmdmg oft' the steel needle at its point of reinforcement. 
 The sterile needle should be kept in well-protected glass contamers. 
 The needles are sterilized after each use by boiling in plain water, 
 dried with the hot air s^Tino;e. and immediateh' transferred to a 
 
514 LOCAL ANESTHESIA 
 
 covered sterile glass dish. The dried sterile needles should not be 
 touched again with the fingers, and the customary wire insertion is 
 unnecessary. 
 
 TECHNIC OF THE INJECTION. 
 
 Various methods of injecting solution about the teeth are in vogue. 
 For the sake of convenience, we may be permitted to divide them as 
 follows : 
 
 1. Terminal anesthesia: 
 
 Subperiosteal injection. 
 Peridental injection. 
 
 2. Conduction anesthesia. 
 
 Injection at the infra-orbital foramen. 
 Injection at the maxillary tuberositj^ 
 Injection at the incisive foramen. 
 Injection at the posterior palatine foramen. 
 Injection at the mandibular foramen. 
 Injection at the mental foramen. 
 
 3. Pulp anesthesia. 
 
 Before starting any surgical interference in the mouth, the field of 
 operation should be thoroughly cleansed and sterilized by painting 
 with diluted tincture of iodin. A serviceable dilution of the tincture 
 for such purposes is made as follows: 
 
 Tinctiire of iodin (U. S. P.) ^ oz. (15 c.c.) 
 
 Aceton 1 oz. (30 c.c.) 
 
 Keep in glass-stoppered bottles and apply with a cotton swab. 
 
 After the diagnosis is made the method of injection best suited for 
 the case in hand is decided upon. The required quantity and concen- 
 tration of the anesthetic solution is now prepared and the syringe a ad 
 hypodermic needle fitted ready for the work. The correct position 
 of the syringe in the hand of the operator and its proper manipula- 
 tion are important factors which are acquired by practice. The hand 
 holding the syringe is governed exclusively in its movement by the 
 wrist, so as to allow delicate and steady movements, and the fingers 
 must be trained to a highly developed sense of touch. The syringe is 
 filled by drawing the solution up into it; it is held perpendicularly, 
 point up, and the piston is pushed upward until the first drop appears 
 at the needle point, which precaution prevents the injection of air into 
 the tissues. 
 
 The Subperiosteal Injection.- — ^The subperiosteal injection about the 
 root of an anterior tooth is best started by inserting the needle midway 
 between the gingival margin and the approximate location of the apex. 
 
TECHNIC OF THE INJECTION 515 
 
 The pain of the first puncture may be obviated by using a fine, very 
 sharp-pointed needle, by the simple compression of the gum tissue 
 with the finger tip or by holding a pledget of cotton saturated with the 
 prepared anesthetic solution on the gum tissue for a few moments. 
 The needle opening faces the bone, the syringe is held in the right hand 
 at an acute angle with the long axis of the tooth, while the fingers 
 of the left hand hold the lip and cheek out of the way. After punc- 
 turing the mucosa, a drop of the liquid is at once deposited in the tissue, 
 and the further injection is painless. Slowly and steadily the needle is 
 forced through the gum tissue and periosteum along the alveolar bone 
 toward the apex of the tooth, depositing the fluid under pressure close 
 to the bone on its upw^ard and return trip. The continuous slow moving 
 of the needle prevents injecting into a vein. A second injection may be 
 made by partially withdrawing the needle from the puncture ard 
 swinging the syringe anteriorly or posteriorly, as the case may be, from 
 the first route of the injection. This latter method is especially indi- 
 cated in injecting the upper molars. After removing the needle, place 
 the finger tip over the puncture and slightly massage the injected area. 
 A circular elevation outlines the injected field. The naturally pink 
 color of the gum will shortly change to an anemic hue, indicating the 
 physiologic action of the epinephrin on the circulation. No wheal 
 should be raised by the fluid, as that would indicate superficial infil- 
 tration and consequently failure of the anesthetic. 
 
 As the liquid requires a definite length of time to pass through the 
 lamina of bone so as to reach the nerves of the peridental membrane 
 and the pulp, from five to ten minutes should be allowed before the 
 extraction is started. The length of time depends on the density of 
 the surrounding bony structure of the tooth. The progress of the 
 anesthesia may be tested with a fine pointed probe, and its complete- 
 ness indicates the time when the extraction should be started. 
 
 The upper eight anterior teeth usually require a labial and a lingual 
 injection; the molars require both a buccal and a lingual injection. 
 Buccally the injection should be made midway between the mesial 
 and distal root, and on the lingual side over the lingual root. 
 
 The lower eight anterior teeth are comparatively easily reached 
 by the injection. The needle is inserted near the apices of the teeth, 
 the syringe is held in a horizontal position, and the injection may be 
 made as previously outlined. 
 
 The lower molars require a buccal and a lingual injection. The 
 needle is inserted into the gum margin, midway between the roots and 
 the apices. The external and internal oblique line materially hinders 
 the ready penetration of the injected fluid, and therefore ample time 
 should be allowed for its absorption. 
 
516 LOCAL ANESTHESIA 
 
 If two or more adjacent teeth are to be removed, the injection by 
 means of infiltrating the area near the gum fold directly over the 
 apices of the teeth is to be preferred. It is advisable to use a one inch 
 needle for this purpose, holding the syringe in a horizontal position, 
 so as to reach a large field with a single injection. 
 
 The injection into inflamed tissue, into an abscess, and into phleg- 
 monous infihration about the teeth is to be avoided. The injection 
 into engorged tissue is very painful; the dilated vessels quickly absorb 
 the anesthetic without producing complete anesthesia, and general 
 poisoning may result. In purulent conditions an injection is decidedly 
 dangerous, as it forces the existing infection beyond the line of demar- 
 cation. If the abscess presents a definite outline, the injection should 
 be made into the sound tissue surrounding its focus. If a tooth is 
 affected with acute diffuse or suppurating pericementitis, a distal and 
 a mesial injection usually produce successful anesthesia by blocking 
 the sensory nerve fibers in all directions. 
 
 PERIDENTAL ANESTHESIA. 
 
 Teeth or roots standing singly, or teeth affected by pyorrhea or 
 similar chronic peridental disturbances, are frequently anesthetized 
 quickly and satisfactorily by injecting the anesthetic solution directly 
 into the peridental membrane. This method is known as peridental an- 
 esthesia and its technic is very simple. In single-rooted teeth the short 
 hypodermic needle is inserted under the free margin of the gum, or 
 through the interproximate papilla, into the pericemental membrane 
 between the tooth and the alveolar process. At times the needle may be 
 forced through the thin lamella of bone so as to reach the peridental mem- 
 brane directly. To gain access to this membrane in teeth set close 
 together, slight separation with an orange-wood stick or other suitable 
 means is often found to be of advantage. Two and sometimes three 
 injections are necessary. To force the liquid into the peridental mem- 
 brane usually requires a higher pressure than that which is necessary for 
 injecting the periosteum covering the alveolar process, but the quantity 
 of the anesthetic liquid used is less than that which is required for the 
 former injection. Acute inflammatory conditions of the peridental 
 membrane and its sequelae prohibit the use of this method. Peridental 
 anesthesia is the purest form of local anesthesia, since the seat of the 
 nerve supply of the tooth is very quickly reached,' and as a consequence 
 the results obtained are in the majority of cases extremely satisfactory, 
 provided that general conditions justify its application. 
 
 Injection at the Infra-orbital Foramen. — ^To reach the nerve plexus 
 which passes through the infra-orbital foramen and furnishes inner- 
 
PERIDENTAL ANESTHESIA 517 
 
 vation to the upper incisors and cuspids, an injection is readily 
 made in this region and it is always followed by the desired results. 
 The infra-orbital foramen is easily located about one-quarter inch 
 below the middle of the inferior ridge of the orbit by palpating with 
 the index finger of the left hand. The lip is drawn up with the thumb 
 of the same hand and the one and a half inch needle is inserted into 
 the gum fold between the cuspid and the first bicuspid teeth. Slowly 
 the needle is forced upward along the surface of the bone, injecting 
 a few drops of fluid on its way until the needle point is felt under the 
 ball of the compressing finger resting over the foramen. The syringe 
 is now slowly emptied and withdrawn. 
 
 After the injection, slight massage is advantageous in every case. 
 To reach those branches of the anterior superior dental nerve which 
 enter into the body of the maxillary bone, a good sized cotton tampon 
 
 Fig. 412. — ^Average range of anesthesia after an injection about the infra-orbital foramen. 
 
 saturated with a 20 per cent, solution of novocain in distilled water is 
 placed in the lower meatus of the nose and left there during the oper- 
 ation. A few drops of the anesthetic solution injected about the 
 marginal gum tissues of the tooth or teeth under consideration will 
 materially assist in obtaining complete anesthesia. 
 
 Injection at the Maxillary Tuberosity. — ^To reach the posterior superior 
 dental nerves which pass through numerous small foramina at the 
 surface of the tuberosity the syringe mounted with a long needle and 
 held at an acute angle is introduced into the half-opened mouth and 
 inserted high up near the reflection of the mucous membrane within 
 the region of the second molar. The needle, lying close to the bone is 
 pushed slowly backward, upward and inward and simultaneously 
 about 1 to 1| c.c. of the solution is slowly injected. 
 
 In many instances the lower border of the spheno-maxillary fossa 
 is reached which materially assists in the dissemination of the fluid 
 
518 LOCAL ANESTHESIA 
 
 within the vicinity of the foramen rotundum through which the second 
 division of the fifth nerve passes. 
 
 Injection at the Incisive Foramen. — ^The nasopalatine nerves pass 
 through the foramina of Scarpa (incisive foramen) which are located 
 
 Fig. 413. — Average range of anesthesia after an injection about the posterior dental canal. 
 
 (Maxillary tuberosity.) 
 
 within the suture of the maxillary bones. If an imaginary line passing 
 over the hard palate is drawn from the distal borders of the two cuspids, 
 the line will ordinarily pass through the foramina. If the needle is 
 inserted into the papilla directly back of the two upper central incisors, 
 on its upward course it will pass directly into the foramen. Eight to 
 
 Fig. 414. — Average range of anesthesia after an injection about the incisive foramen. 
 
 ten drops of the solution slowly injected are usually followed by intense 
 blanching of the anterior palate. 
 
 Injection at the Posterior Palatine Foramen. — ^The posterior palatine 
 foramen is usually easily recognized by a slight depression in the 
 
PERIDENTAL ANESTHESIA 519 
 
 mucous membrane about one-half inch above the border of the alveolar 
 process near the last erupted molar. The short needle is inserted in 
 advance of the depression and gently pushed backward and upward; 
 about eight to ten drops of the solution are injected. 
 
 Fig. 415. — Average range of anesthesia after an injection about the posterior palatine 
 
 foramen. 
 
 Injection at the Mandibular Foramen. — ^The successful anestheti- 
 zation of the lower molars by the subperiosteal injection is frequently 
 
 Fig. 416. — Average range of anesthesia after an injection about the mandibular fora- 
 men. The shaded area is innervated by fibers of the buccal nerve and requires an 
 additional subperiosteal injection within that region. 
 
 fraught with many difficulties on account of the h.esi\y bony ridges 
 on both sides of the teeth, which form strong barriers to the ready 
 penetration of the solution into the bone. To overcome these difficulties 
 Braun, in 1905, introduced a method, originally suggested by Halstead, 
 
520 LOCAL ANESTHESIA 
 
 in 1885. of centrally anesthetizing the mandibular and, incidentally, 
 in many instances, the lingual nerve near the region of the mandibular 
 foramen. 
 
 By palpating the surface of the ramus in the open mouth with the 
 finger, the anterior sharp border of the coronoid process is easily felt 
 about three-quarters of an inch posterior of the third molar. The 
 process passes downward along the side of the last molar, and loses 
 itself in the external oblique line. Mesially from this ridge is to be 
 found a small triangular concave fossa, which faces downward and 
 outward, bounded lingually by the internal oblique line and covered 
 with mucous membrane. As there is no anatomic name attached to 
 this space, Braun has called it the retromolar triangle. Immediately 
 back of the lingual border of this triangle, directly beneath the mucous 
 membrane, lies the lingual nerve, and about three-eighths of an inch 
 farther back the mandibular nerve. This last nerve lies close to the 
 bone, and enters into the mandibular foramen which is located at the 
 lower border of the mandibular sulcus and is partially covered by 
 the mandibular spine or lingula. 
 
 Before starting the injection the patient should be cautioned to rest 
 his head quietly on the head-rest of the chair, as any sudden movement 
 or interference with the hand of the operator may be the cause of 
 breaking the needle in the tissues. 
 
 The syringe is provided with a one and a half inch needle, held in a 
 horizontal position and placed in the half open mouth across the tongue 
 in the direction of the internal oblique line of the ramus. The needle 
 opening faces the bone. The body of the syringe should rest between 
 the cuspid, lateral incisor, or bicuspid, as the case may be. The 
 thumb or the index finger of the left hand should be employed for 
 palpating the retromolar triangle and the nail edge should be placed 
 directly over the border of the internal oblique line. This point marks 
 the place for the insertion of the needle. The beginner usually selects 
 a point too far mesially. At the moment of inserting the needle, the 
 nail of the finger is withdrawn and the needle strikes the bone directly 
 beneath the mucous membrane about one-half inch above the occlud- 
 ing surface of the last molar. The needle should be slowly advanced 
 along the surface of the bone and at the same time the syringe should 
 be swung gradually toward the other side of the mandible so as to 
 rest upon the occluding surfaces of the teeth. The touch of the bony 
 surface of the ramus which had been lost for a few moments, is again 
 felt and the needle steadily advances in the direction of the mandi- 
 bular spine. From now on, the touch with the bone must never be 
 lost. About I c.c. of the anesthetic solution should be injected on 
 its way to the sulcus and about 1| c.c. deposited under steady backward 
 
PERIDENTAL ANESTHESIA 
 
 521 
 
 and forward motion of the needle within the region of the manthbular 
 fossa. From fifteen to twenty minutes are usually required for the 
 anesthetization of the mandibular nerve. A slight infiltration of the 
 gum tissue about the teeth to be operated upon insures a painless 
 operation. Injection at the mandibular foramen is possible only 
 when the patient can open the mouth sufficiently to allow the ready 
 introduction of the syringe. If the tissues about the third molar are 
 infiltrated with inflammatory exudates, local anesthesia is absolutely 
 prohibited. 
 
 Conduction anesthesia of the mandible is serviceable if a number of 
 teeth are to be removed at one sitting. It should be borne in mind, 
 however, that in general only one-half of either jaw should be anes- 
 thetized at one sitting, so as to keep the quantity of the injected 
 anesthetic solution within the limits of ordinary dosage. 
 
 Fig. 417. — -Average range of anesthesia after an injection about each of the mental 
 
 foramina. 
 
 Injection at the Mental Foramen. — ^The mental foramen is usually 
 easily located by exerting slight pressure near the apices of the first 
 and second bicuspids upon the buccal surface of the mandible. The 
 needle should be inserted in this region holding the syringe in a per- 
 pendicular position pointing dowai-ward. The finger tip should be 
 placed over the foramen to act as a guide to the needle in its slightly 
 forward and downward course. About ten to tweh^e drops should be 
 injected and slight pressure exerted by the finger which will assist in 
 the passage through the foramen into the mandible. 
 
 Pulp Anesthesia,^ — By pressure anesthesia, pressure cataphoresis, 
 pulp anesthesia, or contact anesthesia, as this process is variously 
 termed, we understand the introduction of an anesthetizing agent in 
 
 1 The omission of a discussion of the use of arsenic for pulp devitalization should not 
 be interpreted to be a condemnation of this drug. 
 
522 LOCAL ANESTHESIA 
 
 solution by mechanical or electric force through the dentin into the 
 pulp or directly into the exposed pulp for the purpose of rendering this 
 latter organ insensible to pain. Simple hand pressure with the finger or 
 with a suitably shaped instrument, with the hypodermic syringe or with 
 the so-called high pressure syringe, is recommended for such purposes. 
 
 Before describing the modus operandi of the various methods, the 
 histologic structure of the dentin should be recalled briefly. Dentin 
 is made up of about 72 per cent, inorganic salts, about 10 per cent, water 
 and an organic matrix constituting the remaining per cent. The dentin 
 is traversed by a large number of more or less wave-like tubuli, radiat- 
 ing from the pulp cavity toward the periphery, where they branch off, 
 forming a deltoid network. Roemer has counted about 30,000 dentinal 
 tubuli within the area of a square millimeter. These tubuli are filled 
 with processes of the odontoblasts, known at present as "Tomes" 
 fibers, and they are concerned with the metabolic changes occurring 
 in the dentin. The dentinal fibrils are protoplasmic in their nature and 
 normally do not carry physiologic sensation in the sense we under- 
 stand this term. We can cut, file, or otherwise injure the sound dentin 
 without much inconvenience to the patient. When the fibers have 
 become highly irritated, a mere touch upon the dentin may at once call 
 forth a paroxysm of pain. 
 
 1. When the Pulp is Exposed or Covered with a Layer of Decalcified 
 Dentin. — Isolate the tooth with the rubber dam, and clean it with 
 water. Excavate the cavity as much as possible, and, if the pulp is 
 not fully exposed, wipe out the cavity with chloroform to remove 
 fatty deposits from the cartilaginous layer of dentin, and dehydrate 
 with absolute alcohol and warm air. Saturate a small pledget of cotton 
 with a warm concentrated novocain solution in sterile water, carry it 
 into the prepared cavity and cover it with a large pledget of cotton, and 
 then, with a piece of slightly warmed unvulcanized rubber which should 
 completely fill the cavity, and with a broad-faced amalgam plugger or 
 some other suitably shaped instrument, apply slowly, increasing pres- 
 sure from one to three minutes. The pulp may now be fully exposed 
 and tested. If it is still sensitive, repeat the process. Loefiler states: 
 "This pressure may be applied by taking a short piece of orange wood, 
 fit it into the cavity as prepared, and direct the patient to bite down 
 upon this with increasing force. In this way we can obtain a well- 
 directed regulated force or pressure, and with less discomfort to the 
 patient and the operator." Miller describes his method as follows: 
 "After excavating the cavity as far as convenient and smoothing the 
 borders of it, take an impression in modelling compound, endeavoring 
 to get the margins of the cavity fairly well brought out; put a few 
 threads of cotton into the cavity and saturate them thoroughly with 
 
PERIDENTAL ANESTHESIA 
 
 523 
 
 a 5 to 10 per cent, solution of novocain, cover this with a small bit of 
 rubber dam, and then press the compound impression down upon it. 
 A perfect closure of the margin may thereby be obtained, so that the 
 liquid cannot escape, and one can then exert pressure with the thumb 
 sufficient to press the solution into the dentin." Instead of novocain 
 solution, a so-called novocain "pluglet" may be used. A pluglet is 
 introduced into the cavity covered with a wisp of cotton dipped in 
 sterile water and the further procedure is precisely the same as des- 
 cribed above. 
 
 2. When the Pulp is Covered with a Thick Layer of Healthy Dentin. — 
 With a very small bibeveled drill bore through the enamel or directly 
 into the exposed dentin at a convenient place, guiding the drill in the 
 direction of the pulp chamber. Blow out the chips, dehydrate with 
 
 Fig. 418 
 
 alcohol and warm air and apply the hypodermic or high pressure 
 syringe, provided with a special needle, making as nearly as possible 
 a water-tight joint. Apply slow, continuous pressure for two or three 
 minutes. With a bur the pulp should now be exposed, and, if still 
 found sensitive, the process should be repeated. As an anesthetic for 
 this purpose a 5 or 10 per cent, solution of novocain in sterile water is 
 recommended. Or a wisp of cotton saturated with the same solution 
 or a moistened novocain pluglet may be placed in the hole, and then 
 covered with an instrument that will just about fit into the opening. 
 Slight pressure should then be exerted. 
 
 Within recent years a number of complicated syringes, variously 
 known as high pressure syringes or obtunders, have been advocated. 
 Their mechanism is based upon the conception of forcing anesthetic 
 solutions through sound tooth substance by high pressure. Close 
 
524 LOCAL ANESTHESIA 
 
 contact of the anesthetic fluid with the dentinal fibers, plus the neces- 
 sary time for conveying the absorbed anesthetic via the Tomes' fibers 
 to the nerve endings in the pulp, explains the phenomenon very plaus- 
 ibly. A strong metal syringe, provided with an especially prepared 
 needle to make as nearly as possible a water-tight joint, is all that is 
 required. Those who prefer a special high pressure syringe for such 
 purposes may purchase any one of the many devices that will suit 
 their fancy. The Weaver obtunder and the Jewett-Willcox syringe 
 are much lauded for such purposes. 
 
 Any one of the various methods for anesthetizing a tooth as outlined 
 in the preceding discussion may also be used for anesthetizing the pulp. 
 
 In teeth not fully decalcified and in so-called "soft" teeth, pressure 
 anesthesia produces most satisfactory results, while the process fails 
 in teeth of old persons, teeth of inveterate tobacco chewers, worn, 
 abraded, and eroded teeth with extensive secondary calcified deposits, 
 teeth whose pulp canals are obstructed by pulp nodules, teeth 
 with metallic oxids in tubuli, teeth with leaky old fillings, mainly from 
 the same cause, namely, clogged tubuli. In most cases no amount 
 of persistent pressure will prove successful. According to Hertwig 
 the protoplasm of the cell primarily transfers irritation, and secon- 
 darily, transmits absorbed materials, and therefore the anesthetic 
 solution has to pass through the entire length of the dentinal fiber 
 before the nerve tissue of the pulp is reached. Consequently a certain 
 period of time is required before the physiologic effect of the anes- 
 thetic is manifested, and this period of latency is dependent upon the 
 thickness of the intermediate layer of dentin. The successful anes- 
 thetization of the pulp depends largely upon this most important 
 factor of allowing sufficient time for the proper migration of the drug. 
 
 Other soluble local anesthetics, such as nervocidin, erythrophlein 
 hydrochlorid, quinin and urea hydrochlorid, etc., have been advised 
 at various times as reliable pulp anesthetics. Owing to numerous 
 drawbacks, these drugs have never obtained popularity. Refrigerant 
 local anesthetics have also been advised for the extirpation of the pulp. 
 The application of this group of anesthetics for such purposes is usually 
 accompanied by many disadvantages which materially limit its useful- 
 ness. 
 
 Local Anesthesia for Operations about the Mouth, Exclusive of the 
 Extraction of Teeth. — In operating about the mouth for a cyst, a tumor, 
 etc., the rhomboid infiltration of the affected tissue according to 
 Hackenbruch affords the simplest means of producing a most satis- 
 factory anesthesia. 
 
 The needle is inserted at (a), and at once slow pressure is exerted 
 on the piston, moving the needle steadily along the external line of 
 
PERIDENTAL ANESTHESIA 525 
 
 the tumor. The needle is now partially withdrawal, without, however, 
 leaving the original puncture, and a second injection or as many as 
 may be needed are made in opposite directions. This maneuver is 
 now repeated at (6), and thus a circumscribed infiltration of the whole 
 tumor is obtained. If the tumor, etc., be very large, additional punc- 
 tures and injections may be made as outlined in the schematic drawing. 
 After waiting ten to fifteen minutes, the extirpation of the tumor 
 may be begun. 
 
 The anesthetization of the soft and hard palate is accomplished 
 comparatively easily. The injection on the hard palate is started at 
 the gingival edge of the alveolar periosteum on both sides of the jaw 
 toward the median line. As the gum tissue is extremely dense, great 
 force is required for a complete infiltration in this region, and only 
 small quantities of the solution are required. The soft palate is easily 
 infiltrated by inserting the needle posteriorly to the third molar. 
 
 Fig. 419 
 
 Small tumors and cysts on the tongue or the floor of the mouth are 
 best anesthetized by the rhomboid infiltration of Hackenbruch. For 
 the complete extirpation of a ranula, the injection is made into the cyst 
 wall near its periphery, after which the cyst is slit open and a small 
 quantity of the anesthetic solution is injected into its inner surface. 
 Large cysts, tumors, and major operations on the tongue requu-e the 
 anesthetization of both lingual nerves. In injecting and operating 
 on the floor of the mouth, the index finger of the left hand should be 
 placed on its external surface as a guide to the needle or the knife. 
 
 Local anesthesia is indicated in most minor and, relatively, in many 
 major operations on the mucous surfaces, the skin, and the teeth. 
 Local anesthesia is not a substitute for general anesthesia; its useful- 
 ness is materially increased by familiarizing one's self with the methods 
 of its production and with a perfect mastery of its technic. The danger 
 of poisoning has been eliminated by using an isotonic solution contain- 
 
526 LOCAL ANESTHESIA 
 
 ing a relatively small percentage of the anesthetic in combination with 
 epinephrin. Even if the danger of general narcosis is small under the 
 very best conditions, the danger of local anesthesia is always less. 
 The great majority of all dental operations can be safely carried out 
 under local anesthesia, provided the operator has acquired a complete 
 working knowledge of the various components, which, as a whole, con- 
 stitute this important branch of dental therapeutics. 
 
CHAPTER XIII. 
 
 PYORRHEA ALVEOLARIS. 
 
 By RUSSELL W. BUNTING, D.D.Sc. 
 
 The term pyorrhea alveolaris, meaning a flow of pus from the 
 alveolus, has been given a very broad application. Strictly speaking, 
 it should be applied only to the pyogenic forms of peridental infection 
 by which the tissues about the teeth are broken down with a resultant 
 formation of pus. But by common usage the term pyorrhea has 
 been loosely applied to all peridental diseases which are related to the 
 gingivae, including infective, non-infective, purulent and non-purulent 
 types. As a large number, if not the majority, of peridental infections 
 are non-purulent in character, it follows that the term pyorrhea is 
 very often a misnomer for the conditions to which it is applied. An 
 effort therefore has been made to find a more suitable name by which 
 the various peridental affections might be designated. Among other 
 terms which have been suggested, periodontoclasia {peri about, odon 
 tooth, klasis a breaking, literally a breaking about the tooth) has 
 received the widest acceptance. This term for the sake of brevity 
 and euphony may be shortened to dental periclasia of which several 
 types may be differentiated, as suppurative, non-suppurative, gingival, 
 alveolar, etc. Although these terms are in many respects commendable 
 and are the most comprehensive so far suggested, their usage at the 
 present time is very limited. In view of this fact, for the sake of clarity 
 we will use in this discussion the following two terms: gingivitis, which 
 will include all disturbances of the gingivae in which little or no loss 
 of attachment of the soft tissues to the teeth has been effected, and 
 pyorrhea alveolaris, which will be applied to those forms of peridental 
 disease in which the attachment of the hard and soft tissues has been 
 destroyed an appreciable distance down the side of the root. It will 
 be necessary, therefore, to use the anomalous term non-purulent pyor- 
 rhea, but in doing so it must be remembered that pyorrhea refers, in a 
 generic sense, to a general class of peridental diseases. 
 
 The history^ of the development of our knowledge of pyorrhea, like 
 that of dental caries, is an interesting one. Examinations of the skulls 
 of prehistoric man show that even these peoples were afflicted with 
 
 1 The early history of pyorrhea is largely taken from the account by E. C. Kirk in 
 the American System of Operative Dentistry, 1914. 
 
 (527) 
 
528 PYORRHEA ALVEOLARIS 
 
 peridental diseases, and early writings make frequent mention of mouth 
 affections which caused the teeth to loosen and fall out. The earliest 
 recorded treatise dealing with the disease is that of Pierre Fauchard 
 in 1728 who described its most prominent clinical features. Following 
 the work of Fauchard, sporadic writings appeared from various sources 
 in which meager descriptions of the symptoms and course of pyorrhea 
 were related. In 1867 E. Magitot made an important contribution 
 to the subject in which he described the disease as a progressive 
 inflammation which destroyed the periosteal membrane and cementum. 
 He thought that these conditions originated deep in the tissues and 
 were not necessarily preceded by gingival irritation or inflammation. 
 He attributed their cause to constitutional changes and associated 
 them with gout, diabetes, albuminuria, and rheumatism. 
 
 In 1880 Serran took exception to the views of Magitot, and stated 
 as his opinion that all peridental diseases began in an inflammation 
 of the gingival tissues due to the presence of infection or calculi about 
 the teeth. He believed them to be manifestations of purely local 
 conditions and not necessarily dependent upon general or systemic 
 states. Because of the widely diverging views of these writers and 
 the discussions which grew out of them, the Societe de Chirurgie of 
 Paris appointed a commission of scientists to investigate the matter 
 to determine which of the two theories was the more tenable. In the 
 report^ which they gave at the conclusion of their study of the problem 
 the commission corroborated the views of Magitot. They stated that 
 peridental diseases did not begin as gingival affections but rather that 
 the primary lesion occurred deep in the pericementum and that the 
 gingivae were affected only secondarily. They held that the disease 
 was not due therefore to local causes, but was rather a manifestation 
 of constitutional disturbance. 
 
 In this country the first important contribution to the subject was 
 made by John W. Riggs of Hartford, Conn., in 1875.^ He emphatically 
 denied that peridental disease arose from constitutional causes. On 
 the contrary, he claimed that it began as a local inflammation of the 
 gingival tissues which in turn was caused by the irritation of calculi 
 and other accretions upon the teeth contiguous to or beneath the free 
 margin of the gums. His views were based largely upon his practical 
 observations that if in the treatment of pyorrhetic affections the 
 accretions be completely removed from the teeth, the disease is usually 
 arrested and permanently controlled. These views concerning the 
 etiology of peridental diseases and the clinical demonstrations which he 
 made setting forth the manner of their treatment aroused so much 
 
 1 Bulletin et Memoirs de la Soc. de Chir., Tome vi, p. 411. 
 
 2 Pennsylvania Journal of Dental Science, vol. iii, p. 99. 
 
PYORRHEA ALVEOLARIS 529 
 
 interest that for many years this condition was known as "Rigg's 
 disease." 
 
 During the years that have followed, students of these affections have 
 been divided into two classes: one, the localists who believe that the 
 disease is purely a local disturbance arising from causes that are 
 proximate in origin, while the other group might be called the consti- 
 tutionalists who believe that pyorrhea occurs entirely independent of 
 local conditions and that it is in reality an expression of constitutional 
 disturbance or disease. Among the more important writings on the 
 subject are those of G. V. Black^ who treats pyorrhea alveolaris as a 
 purely local disease. He considers it to be largely an inflammation 
 and destruction of the peridental membrane by a process which is 
 specific in character. He describes the initial lesion as an invasion of 
 the peridental membrane by certain infectious organisms which pene- 
 trate deeply into the tissues along the so-called pericemental glands of 
 Black. The infections which have thus gained entrance to the deeper 
 tissues set up inflammations and degenerative changes which spread 
 to the adjacent alveolar process and cause their destruction. 
 
 A somewhat different view was expressed by A. Witzel of Germany^ 
 who stated that peridental disease begins as an inflammation and caries 
 of the alveolar border. As a result of the bone destruction a deposit 
 of calculus is formed upon the teeth just beneath the free margin 
 of the gum, which in turn constitutes a source of irritation to the 
 gingival tissues producing gingivitis and disturbances in the surround- 
 ing tissues. Witzel claims that this process is wholly local and inde- 
 pendent of constitutional states, but that it originates in the deeper 
 bony structures about the teeth rather than at the gum margins. 
 
 As a result of his close microscopic study of peridental tissues in 
 disease, Zamnesky^ has given a very clear description of the process 
 by which they are destroyed. He believes that pyorrhea begins as an 
 inflammation of the gum margin destroying first the epithelial lining of 
 the gingival crevice and gradually involving the deeper soft and hard 
 tissues to produce necrotic changes in them. Therefore he considers 
 the process to be a local necrotic disintegration of the alveolar process 
 which begins with gingival inflammation. 
 
 Eugene S. Talbot who since 1896 has written voluminously on the 
 subject,^ takes a middle ground in the discussion. He recognizes the 
 
 1 American System of Dentistry, vol. v, p. 953; Operative Dentistry, G. V. Black, 
 1908, and Special Dental Pathology, G. V. Black, 1915. 
 - British Journal of Dental Science, vol. xxv, p. 153. 
 
 3 Journal of British Dental Association, vol. xxiii, p. 585. 
 
 4 Talbot: Dental Cosmos, 1896, pp. 310, 660; ibid., 1905, p. 310; 1909, p. 1147; 1915, 
 p. 485. Talbot: Dental Summary, 1903, pp. 435, 538; ibid., 1917, p. 282. Talbot: 
 Dental Items of Interest, 1906, p. 837. Talbot, E. S.: Interstitial Gingivitis, 1899 and 
 1913. 
 
 3i 
 
530 PYORRHEA ALVEOLARIS 
 
 importance of certain local causative factors such as infection, calculi, 
 etc., but he believes that the most significant factor in the process 
 is a preliminary degeneration of the alveolar process. He points out 
 that because of evolutionary development of man a marked degenera- 
 tion of the alveolar process has occurred with the result that in the 
 present generation these bones are lightly built and are prone to 
 degenerative changes under any stress or nutritional disturbance. 
 He states that the initial lesion therefore consists in preliminary 
 degeneration of the alveolar bone due to senility, constitutional fault, 
 poisons, etc. If, then, local irritative factors be present, they acting 
 in conjunction with the underlying degenerative changes, may produce 
 the characteristic lesions of the disease. If, on the contrary, oral 
 hygiene has been maintained and no local irritations are present the 
 degeneration of the bone results in an atrophic shrinkage of the soft 
 and hard tissues about the teeth rather than in true pyorrhea. 
 
 More recently, however, the great majority of writers and con- 
 tributors have leaned toward the localist's point of view, giving special 
 emphasis to the part played by the infectious organisms involved. 
 Inasmuch as bacteria and other mouth organisms are present in every 
 case of pyorrhea, it has always been a matter of speculation as to 
 whether these organisms were primarily responsible for the disease or 
 only secondary inhabitants of the lesions. Exhaustive studies of the 
 bacteriology of pyorrhea have been made by various investigators each 
 of whom has searched for some ever-present predominating organism 
 which might prove to be the specific cause of the disease. 
 
 W. D. Miller^ isolated from pyorrheal pockets the Staphylococcus 
 aureus and albus and Streptococcus pyogenes, and described about 
 sixteen other types of organisms which he did not isolate. He stated 
 that pyorrhea is essentially an infective process in which the peridental 
 tissues are destroyed by bacteria. These organisms he found thriving 
 in the lesions in a mixed culture, several different forms usually being 
 present in symbiotic relationship to each other. As he could determine 
 no constant type or group of organisms which was uniformly present 
 in every case. Miller concluded that pyorrhea may be produced by a 
 wide group of organisms in varying combinations and is not caused 
 by any specific type of bacteria. 
 
 Vaccine Therapy.^ — Kenneth Goadby^ also studied the bacterial 
 flora of pyorrhea and found that S. pyogenes, M. catarrhalis and S. 
 albus and aureus are the most frequent organisms met with in this 
 disease. He claimed he had succeeded in curing cases of pyorrhea by 
 the use of autogenous vaccines made from the organisms present in 
 
 1 Microorganisms of the Human Mouth, 1890, p. 329. 
 
 2 British Medical Journal, 1905, vol. ii, p. 562. 
 
VACCINE THERAPY 531 
 
 the lesions. In his attempt to control pyorrhea by vaccines he was 
 pioneer in the practice of vaccine therapy for that disease, a method 
 which later came into considerable prominence and which for a time 
 was very widely adopted. 
 
 Notable in this connection is the work of L. S. Medalia who, begin- 
 ning with 1913^ wrote several extensive articles on the bacteriology of 
 pyorrhea and the treatment of the disease by vaccine therapy. He 
 quotes Zamnesky^ in slipport of his opinion that pyorrhea is essentially 
 an affection of the bones and therefore should be known as chronic 
 alveolar osteo-myelitis. He believes that these tissue degenerations 
 are produced by local infections which are variable in character, no one 
 organism being the specific cause. For the control of these infections 
 he recommends the use of autogenous vaccines for the purpose of 
 raising the opsonic index of the body against the particular strains of 
 bacteria which happen to be present in the lesions. By vaccine therapy 
 in conjunction with oral prophylactic measures Medalia claims to have 
 had a high percentage of cures. 
 
 As a result of the statements made by Medalia and others regarding 
 the benefits which were to be derived from the use of vaccines in the 
 treatment of pyorrhea, many dental investigators and practitioners 
 made practical application of the measures suggested, the reports of 
 which show a varying degree of success. Very soon those who were 
 most conversant with the disease and who had the widest experience 
 in its treatment lost faith in vaccine therapy and discontinued its use. 
 They arrived at the conclusion that^ the promiscuous use of vaccines 
 is dangerous, that vaccines when used for pyorrhea are not specific 
 in their action, and that the disease might be successfully controlled 
 by the more simple measures of surgical interference, without which 
 the vaccine would be of no avail. 
 
 One of the most serious objections to the use of vaccines for the 
 treatment of pyorrhea is the fact that they are misleading in their 
 symptomatology. It is true that following the injection of autogenous 
 and even stock vaccines a marked improvement of the case is fre- 
 quently seen. The pus flow may cease and the peridental inflammation 
 may rapidly decrease; so that from superficial observation it might 
 appear that the case were permanently cured. But unless by careful 
 instrumentation all accretions have been removed from the denuded 
 roots and the root-surfaces carefully planed no permanent reattach- 
 ment of the soft tissues to the root can take place. Many operators, 
 therefore, who depend upon vaccine therapy in the treatment of 
 
 1 Dental Cosmos, 1913, p. 24. 
 
 ^ Journal British Dental Association, vol. xxiii, p. 585. 
 
 3 Merritt: Dental Cosmos, 1916, p. 62. 
 
532 PYORRHEA ALVEOLARIS 
 
 pyorrhea, being deceived by the chnical improvement of the case, fail 
 to perform the necessary operative procedures with the result that the 
 pockets still remain about the teeth to be reinfected at a subsequent 
 time. Vaccines then are but temporary in their action and may be 
 considered only in the light of questionable adjuncts to surgical pro- 
 cedures. Today vaccine therapy in the treatment of pyorrhea has 
 largely fallen into disrepute and is only used in a limited way by a few 
 of its most ardent supporters. '■ 
 
 The Ameba Theory. — Perhaps no subject ever caused such widespread 
 interest in the dental world in so short a time as did the announce- 
 ment of Endameba buccalis as the specific cause of pyorrhea alveo- 
 laris by the simultaneous reports of three independent groups of men. 
 In July, 1914, Angelo Chivaro'^ in a paper given before the American 
 Dental Society of Europe in Paris, states that the Endameba buccalis 
 is usually present in the "materia alba" of unclean mouths and is 
 always found in pus from pyorrheal pockets. He advances the 
 opinion that "the endameba has not a pathogenic action; on the 
 contrary, as it feeds on bacteria, it is most probably an aid to auto-- 
 disinfection of the mouth." It is evident, therefore, that he considered 
 the endameba in the light of a mouth scavenger and not as a cause of 
 pyorrhea. 
 
 During the same month M. T. Barrett^ before the Pennsylvania 
 State Dental Society in Philadelphia gave a preliminary report of the 
 studies which he and A. J. Smith had made of the endameba in pyor- 
 rhea. In this and subsequent writings, Barrett and Smith place great 
 stress on the supposed pathogenic action of oral amebse, characterizing 
 them as the specific cau,se of pyorrhea, although they admit that 
 bacteria may have a part in the destructive process. Being confident 
 of the validity of their claims they began the administration of emetin, 
 a specific drug for ameba, which they gave in the form of subcutaneous 
 injection, mouth washes, and by stomachic dosage. In the use of this 
 amebacidic treatment, Barrett and Smith and their collaborators 
 claim to have had many remarkable cures of pyorrhea. 
 
 In September, 1914, Bass and Johns of New Orleans read a paper^ 
 on the amebic theory of pyorrhea in which they hastened to publish 
 the results of their investigations, which according to their own state- 
 ment, had not been pursued more than one month. As the result of 
 this brief consideration they announced as their opinion that amebse 
 are the specific cause of pyorrhea, that they are not to be found on 
 
 1 Dental Review, 1914, p. 1122. 
 
 2 Dental Cosmos, August, 1914, p. 948. 
 
 ' Dental Summary, December, 1914, p. 994, and Jour. Amer. Med. Assn., February 
 13, 1915, p. 553. 
 
SUCCINAMIDE OF MERCURY 533 
 
 open surfaces or in healthy mouths, and that the use of amebacides 
 will cure pyorrhea. They later published a book entitled "Alveolo- 
 dental Pyorrhea" in which they considered the various types of the 
 disease as being produced by endameba buccalis. 
 
 From the extravagance of the claims made by the American expon- 
 ents of this theory, a widespread interest was aroused and as a conse- 
 quence, a wholesale use of emetin in the treatment of pyorrhea followed. 
 At the same time careful studies of the theory were made by dental 
 scientists and practitioners who sought to know the truth about the 
 matter. Notable among these are the investigations of Price and 
 Bensing^ who describe the various types of amebse which inhabit the 
 mouth. They found, as did Chivaro, that the amebse ingested bacteria, 
 from which fact they inferred that these protozoa were beneficial to 
 the tissues rather than harmful to them. HartzelP made practical 
 and clinical studies of the effect of emetin on cases of pyorrhea, the 
 results of which convinced him that such medication was of doubtful 
 value, and that proper surgical and prophylactic means would effect 
 a cure without the aid of emetin. The views of Hartzell were 
 corroborated by practically all practitioners who treated pyorrhea 
 intensively. The great mass of evidence and opinion which was 
 given out by those who studied the subject was largely contradictory 
 to the theory while very little corroboratory evidence could be found. 
 Cases in which emetin was used seemed to show a temporary improve- 
 ment, but, as in the use of vaccines, the operator almost invariably 
 relied so much upon the beneficial effects of the drug that he failed to 
 perform properly the necessary operative and prophylactic measures. 
 As a result, healing of the pockets was not attained and a relapse 
 occurred within a very short time. Consequently the interest which 
 was aroused by the amebic theory of pyorrhea and the use of emetin 
 in its treatment w^as short lived, dying out almost as rapidly as it arose, 
 and the treatment of pyorrhea by means of emetin is no longer practiced 
 except by a very few enthusiasts. 
 
 Succinamide of Mercury. — ^During the year 1915 and later, the dental 
 corps of the Navy reported the successful treatment of pyorrhea by 
 deep muscular injections of succinamide of mercury. G. H. Reed,* 
 Wright,^ and White,^ acting upon the supposition that mercury pro- 
 duces antibodies in the blood and thereby retards the action of parasites, 
 made use of that drug in the form of a succinamide to control the 
 gro\\i;h of the microorganisms in pyorrhea. From its use they claimed 
 
 1 Journal National Dental Association, 1915, p. 143. 
 
 2 Emetin vs. Surgery, Hartzell, Journal Allied Dental Society, 1916, p. 7. 
 ' Items of Interest, April, 1915, p. 241. 
 
 * Dental Cosmos, 1915, p. 1003, and the Journal Allied Dental Society, 1916, p. 305. 
 6 Dental Cosmos, 1915, p. 405. 
 
534 PYORRHEA ALVEOLARIS 
 
 they had obtained pronounced beneficial results in which the pus ceased 
 to flow from the pockets within twenty-four hours after the injection, 
 the inflammation of the tissues subsided and a disappearance of the 
 pyorrheal lesions ensued. It was suggested by them that this method 
 be used in conjunction with careful operative procedures, but beneficial 
 results were noted even when no instrumentation was performed. It is 
 the opinion of Wright that the mercury has a two-fold parasitrophic 
 action: first, the mercury unites directly with the organisms, that is, 
 it forms a chemical combination with the bacterial proteins; and, 
 second; the mercury stimulates in the tissues the formation of a specific 
 antibody against the organisms of pyorrhea. In the treatments which 
 they gave four or five doses of succinamide of mercury were admin- 
 istered one week apart, beginning with f grain and reducing i each week. 
 The injections were made deep in the gluteal muscles alternating each 
 week between the two sides of the buttocks. Only scanty reference 
 has been made to this treatment in the literature, from which we infer 
 that the method has not received any wide acceptance or adoption. 
 There are good reasons to believe that in certain types of cases the 
 administration of the drug in conjunction with careful operative and 
 prophylactic procedures may be of benefit in controlling the infection. 
 This is especially true when the organism present is of a virulent and 
 persistent type which the surrounding tissues are not able to success- 
 fully combat. This form of treatment is, however, open to the same 
 criticism as are vaccines and emetin in that when used to combat 
 pyorrhea it affords a sense of false security by which many operators 
 will be led to neglect or incompletely perform the necessary surgical 
 procedures without which no drug or medicament can effect a cure of 
 the disease. 
 
 More Recent Views of the Cause of Pyorrhea Alveolaris. — In addition 
 to the amebic theory several hj'potheses have been advanced as to 
 the specificity of one or another type of mouth organism to produce 
 pyorrhea. Of these the opinions of Noguchi, Kritchevsky and Seguin, 
 and Hartzell are the most notable. Each of these investigators looks 
 upon pyorrhea as a local infective process in which the peridental tissues 
 are destroyed by a specific type of organism which they believe is 
 responsible for the disease. 
 
 H. Noguchi,^ of the Rockefeller Institute of Medical Research, 
 isolated from pyorrheal pockets and grew in pure culture a new species 
 of spirocheta which he has called the Treponema mucosum. This 
 organism which is smaller than the Vincentini spirillum has regular 
 convolutions similar to the organism of syphilis. They do not grow 
 
 1 Treponema Mucosum, Journal of Experimental Medicine, 1912, xvi, 103. 
 
VIEWS OF THE CAUSE OF PYORRHEA ALVEOLA HIS 535 
 
 on healthy tissues but thrive only on such as have been injured or 
 impaired in their nutrition. They are purulent in type and occasionally 
 stimulate a mucinous secretion. Noguchi recognizes the presence of 
 streptococcus,, staphylococcus and pneumococcus groups, of organisms 
 in peridental disease, but he believes that the Spirocheta mucosum, 
 together with the Spirocheta microdentinum, and the Vincentini 
 spirillum, with the fusiform bacillus, constitute a class of organisms 
 which are directly responsible for the disease. 
 
 In 1918, Kritchevsky and Seguin^ of the Pasteur Institute reviewed 
 the work of Noguchi on Spirochetee and that of Wright, Kolle, and 
 others who claimed to have successfully treated pyorrhea by arsenical 
 and mercurial preparations which have a specific action against 
 spirochete. The authors then reported a large series of pyorrhetic 
 cases which they had treated by intravenous injection and by local 
 application of salvarsan and neosalvarsan. They claimed that in this 
 manner they had obtained very beneficial results consisting of a rapid 
 disappearance of the spirochete from the pyorrheal pockets, and a 
 remarkable improvement in the clinical appearance of the cases. They 
 stated, however, that this treatment alone gives but a temporary relief 
 and that for a permanent cure it is necessary that a most careful scaling 
 and polishing of the roots be performed and a thorough and unrelenting 
 course of oral hygiene be established. 
 
 In a discussion of the cause of pyorrhea, Hartzell in August, 19 18,^ 
 stated emphatically as his belief that it was the streptococcal group of 
 organisms which produced the initial lesion of the disease. As a result 
 of the extensive investigation which he has made of this type of infec- 
 tion during the past five years, he believes that streptococci are neces- 
 sary to true pyorrhea, and that they are the first to penetrate the tissue 
 and create the initial lesion, thus preparing the way for the staphy- 
 lococci and other purulent types of organisms which in turn dissolve 
 the peridental tissues and create the pocket. He emphatically states 
 that the streptococcal, staphylococcal, and pneumococcal group are 
 the only organisms of any importance in pyorrhea, and of these the 
 streptococci are the specific instigators of the process. For the control 
 of these infections and the cure of the disease he depends solely upon 
 the thorough application of surgical and hygienic measures. 
 
 It will be noted that practically all American students of pyorrhea 
 consider it to be a local disease arising largely from local irritations and 
 infections, with the exception of Talbot, who takes a middle ground, 
 believing that both local and constitutional causes are involved. The 
 
 1 La Presse Medicale, Paris, May 13, 1918, and the Dental Cosmos, September, 1918, 
 p. 781. 
 
 2 Items of Interest, January, 1919, p. 45. 
 
536 PYORRHEA ALVEOLAR! S 
 
 majority of European students, however, have taken the opposite view 
 of the question and regard pyorrhea as an expression of systemic disease. 
 Their opinions were very clearly summed up by Maurice Roys^ of 
 Paris in a paper which he gave in London at the Sixth International 
 Dental Congress in 1914. He reviewed the writings of Magitot, 
 Galippe Julien Tellier, Mendell Joseph, Hopewell-Smith, Talbot and 
 others, all of whom placed considerable stress on the early degenerative 
 changes in the alveolar bone in cases of true pyorrhea, Roys then 
 attempts to rule out all other causes of pyorrhea by a process of 
 exclusion and formulates a theory in which he places the greatest 
 emphasis on an initial degeneration of the bone due to what he terms, 
 "precocious senility." He believes that local trauma and infection 
 enter into the process of peridental destruction but considers them to 
 be adjuvant causes and secondary to degenerations in the alveolar 
 bone which are general and systemic in their origin. He asserts that 
 local irritation, such as mechanical stress, infection and faulty oral 
 hygiene, when acting alone, produce gingivitis but not pyorrhea unless 
 a precocious senile degeneration of the alveolar border has taken place. ■ 
 In this manner he explains those cases in which the oral hygiene is 
 poor and the gingivae are inflamed but no pyorrhea is present. On the 
 other hand, he believes that senile degenerations of the alveolar bone 
 without local irritations produce only an atrophy of the peridental 
 tissues, and if a rigid oral hygiene he maintained no pyorrheal pockets 
 will be formed. This contribution of Roys is an excellent exposition of 
 the constitutionalist's conception of pyorrhea and should be carefully 
 studied by all those who are interested in the subject. 
 
 In all of the foregoing the reader will have seen that there are many 
 phases of the problem of pyorrhea alveolaris which at the present time 
 are not fully understood. The variance of opinions which have been 
 expressed has caused considerable confusion in the minds of many as 
 to the nature of the process and the basic principles which are involved, 
 so that it stands today as the least widely understood and most neglected 
 of all dental diseases. Having reviewed the various theories and opin- 
 ions which have been suggested as to the cause and course of pyorrhea 
 alveolaris, we will now consider the known facts regarding the process 
 and point out definitely established principles relative to the practical 
 control of the disease, irrespective of the theories and speculations which 
 have been advanced thereto. 
 
 The Significance of Local Operative Procedures.— During all of the 
 years in which the controversy regarding the cause and nature of 
 pyorrhea has been carried on, a certain group of operators has been 
 
 1 Dental Cosmos, August, 1918, p. 659. 
 
GENERAL PRINCIPLES OF PYORRHEA 537 
 
 successfully treating and controlling pyorrhea by local operative pro- 
 cedures. New theories came and went but these pyorrhea workers 
 continued in the even tenor of their ways to cleanse surgically the 
 affected root-surfaces, to remove all irritants, and to establish per- 
 manent mouth cleanliness, as a result of which an arrest of the destruc- 
 tive process and a subsequent healing of the lesions was secured in a 
 large percentage of cases. So beneficial have been the results obtained 
 by those operators who have become proficient in this form of treat- 
 ment that there is no longer any room for doubt as to the efficacy of 
 these measures to control many forms of pyorrhea. If constitutional 
 factors are involved in their cases, these operators have considered 
 them only in a general way, bending their greatest efforts toward the 
 perfection of a careful technic of root-surgery and the establishment of 
 thorough mouth cleanliness. In a great majority of cases in which the 
 destructive process has not advanced too far an arrest of the disease 
 is effected and a healing of the lesion is brought about while in beginning 
 cases, practically without exception, the pyorrheal tendency is checked 
 and the progress of the disease permanently prevented by local pro- 
 phylactic measures and by the establishment of oral hygiene. By 
 reason of the success which was obtained by these local procedures, 
 many have been led to believe that pyorrhea is wholly a local disease 
 and is entirely independent of systemic conditions. Even those who 
 believe in the constitutional origin of pyorrhea admit that local 
 measures, if thoroughly performed, are largely effective in checking the 
 disease, and indeed there are few who have made a close study of the 
 problem and have impartially adjudged the results of these operators 
 who do not agree as to the efficacy of this method of treatment. The 
 question then arises as to how the conception of pyorrhea as an expres- 
 sion of systemic or constitutional disease may be reconciled with the 
 fact that it is amenable to local treatment. For a better understanding 
 of this phase of the subject it will be necessary to consider more in 
 detail the causes and course of pyorrhea alveolaris. 
 
 General Principles of Pyorrhea. — Pyorrhea alveolaris is a disease of 
 the oral cavity which is confined to the tissues immediately surround- 
 ing the teeth and is characterized by infections, inflammatory changes 
 and a progressive destruction of the attachment of the supporting 
 tissues about the teeth. These degenerations consist in a disintegra- 
 tion of the pericemental membrane and a scission of its fibers beginning 
 at the gingival crevice and proceeding apically along the root of the 
 tooth. Concurrently, degenerative changes take place in the contigu- 
 ous bony structures of the alveolar process by which they undergo 
 molecular disintegration or metaplasia to fibrous tissue. As a result 
 of these two degenerative processes a characteristic lesion or pocket is 
 
538 PYORRHEA ALVEOLARIS 
 
 formed along the lateral surface of the root and is progressively 
 deepened as the disease advances. When the supporting structures 
 have been sufficiently destroyed the tooth becomes loose and eventually 
 is lost. 
 
 This destructive process is not constant or uniform but varies quite 
 widely in its course and the pathologic picture which it presents. In 
 some instances severe inflammation is set up with the production of an 
 active flow of pus while in others the inflammatory reactions are slight 
 and no pus is evident. Certain cases are associated with calculus 
 formation both external and subgingival, while others are devoid of 
 calcareous deposits. Pyorrhea, therefore, is not a definite or specific 
 disease but rather is a variable complex of symptoms expressive of a 
 combination of local and general factors which enter into the process. 
 Of these a wide variety of local irritative and infective factors may be 
 recognized which exercise an evident causal relationship to the disease. 
 These local disturbances are augmented by many general constitutional 
 states which predispose the tissues toward pyorrheal affections. The 
 course of each case is determined by the particular type of local or 
 general factor which is most prominent as a causative agent and the 
 quality of the local tissue reactions. It is, therefore, possible to recog- 
 nize certain definite forms of pyorrhea and to catalogue the various 
 types according to the specific causative agents which are present and 
 the type of tissue reactions to them. For a clear understanding of 
 this complex disease, concerning which there is so much uncertainty 
 and confusion, it is necessary that we learn to analyze each case by rea- 
 soning from cause to effect, that we search for all possible causes both 
 local and systemic, and that we study and evaluate the type of bodily 
 resistance as it is expressed in local tissue reactions. In this manner 
 the course and clinical pictures of a large majority of these cases may 
 be made clear to us so that we may truly appreciate the nature of the 
 pathologic process which has taken place and determine the manner in 
 which it may be checked. 
 
 In the study of pyorrhea alveolaris it is necessary that we consider 
 the structure and peculiar qualities of the tissues which are involved 
 by the disease. The tissues are those which immediately surround 
 the teeth, namely, the alveolar bone, the peridental membrane and the 
 overlying gum tissues (see Fig. 88) . The alveolar process which affords 
 support to the teeth and the soft tissues consists of cancellous bone, 
 except on the periphery and the walls of the alveoli, where it is con- 
 densed and cribriform in type. Normally this alveolar bone surrounds 
 the roots of the teeth nearly to the gingival line and in the interproxi- 
 mate region it projects crownward in a tapering wedge to support the 
 
GENERAL PRINCIPLES OF PYORRHEA 539 
 
 interproxiuiate gingivcv. The peridental membrane lines the walls of 
 each alveolus and by its dense white fibrous tissue gives firm attach- 
 ment betw^een the tooth and the surrounding bone. The peridental 
 fibers also extend upward into the free margin of the gum on all sides 
 of the tooth and by the pull which they exert upon these tissues they 
 serve to draw them tightly about the neck of each tooth. The peri- 
 dental membrane possesses a rich and free blood supply which is derived 
 from vessels which enter the tissue from three sources, namely, at the 
 apex from vessels w^hich enter the pulp, on the lateral surfaces of the 
 root from vessels w^hich enter the membrane through the walls of 
 the alveoli, and in the cervical region from the periosteal circulation. 
 The vessels of the peridental circulation are arranged for the most part 
 parallel with the long axis of the tooth and are accompanied by a 
 system of Ij'mphatics^ which take the same general direction. Overly- 
 ing the bony structure there is first a periosteal covering upon w^hich 
 is superimposed a dense connective tissue submucosa and a highly 
 specialized stratified pavement epithelium, the mucous membrane. 
 These mucous and submucous tissues are firmly attached to the bone 
 by fibers of the periosteum and to the teeth by the fibers of the peri- 
 dental membrane. Unlike the deeper structures the gingival tissues 
 are supplied by bloodvessels w^hich have no collateral communication, 
 being endarterial in tjT)e. 
 
 Normally these tissues are highly resistant to infection and to traum- 
 atic injm'ies incident to the mastication of hard foods. In health, 
 the overlying tissues are hard and firm and are not easily ruptured or 
 torn from their positions. And w^hen they have been injured the oral 
 tissues show^ a remarkable recuperative power by which healing of even 
 severe w^ounds is rapidly accomplished when the injiu-y is not of long 
 diu-ation. But, on the other hand, injuries which are continued for a 
 considerable space of time even though they be of low potential and 
 seemingly insignificant may induce profound degenerative changes in 
 these tissues and a lowering of normal resistive power. These low grade 
 chronic irritations set up circulatory changes in the gingival tissues, 
 namely, active and passive h5T3eremia which, because of the fact that 
 these tissues possess little or no collateral circulation usually terminate 
 in passive congestion and stasis. The vessels become engorged with 
 stagnant or slowly moving blood, the tissues swell and are infiltrated 
 with inflammatory exudates producing a marked distm-bance of the 
 overlying tissues w^hich condition we designate as gmgivitis. These 
 circulatory disturbances vary according to the severity of the irritant 
 
 1 Noyes and Dewey: The Lymphatics of the Dental Region, Jour. Am. Med. Assn., 
 1918, p. 179. 
 
540 PYORRHEA ALVEOLARIS 
 
 and the t^^e of tissue reaction to them. In one individual a given 
 local irritant will give rise to a profound inflammatory reaction and 
 hypertrophy of the gingival tissues, while in another, in response to the 
 same irritant the peridental tissues will degenerate rapidly because of 
 the fact that the local protective reactions are weak. 
 
 If the tissue reactions are sufficiently active, severe inflammations 
 of the gingivae may continue for some time without any serious affection 
 of the deeper tissues or disturbance of their attachment to the roots of 
 the teeth. Gingival inflammation may exist, therefore, for years under 
 these conditions without the production of true pyorrhea. But when 
 the resistive powers of the tissues are not of good order or when a 
 particularly virulent type of organism becomes implanted in a gingival 
 crevice, especially when the gingival circulation has been disturbed 
 by local irritation or by systemic fault, degenerations of the deeper 
 tissues take place. The first step in this process consists in a meta- 
 plasia of the bony alveolar border about the tooth and a dissolution of 
 the peridental fibers. The bony trabeculse undergo halesteresis osseum 
 by which they are decalcified and changed to fibrous tissue. At the 
 same time the peridental fibers are progressively severed and a sub- 
 gingival space or pocket is formed which is open to the gingival crevice, 
 being bounded on one side by the root of the tooth and on the other by 
 the inflamed and degenerating gingival, subgingival and alveolar tissues. 
 
 In this pyorrheal pocket various infectious and pathogenic organisms 
 live and thrive, exerting their characteristic action upon the surround- 
 ing tissues, against which the tissues in tiu-n seek to protect themselves. 
 As in the case of periapical infection the type of protective reaction 
 depends upon the type of organism which predominates in the lesion. 
 When the infection is an actively purulent type, the reactions against 
 the 1 are acute and highly inflammatory. By a profuse diapedesis of 
 leukocytes and lymphocytes a wall is built about the lesion which later 
 becomes organized into a permanent granulation tissue similar to that 
 of an abscess. It then virtually becomes, first an acute and later, a 
 chronic abscess which may persist in statu quo for months or years. 
 After the manner of an abscess, the organisms continually break down 
 tissue, blood, and lymph cells with the production of pus, while the 
 granulations about, either partially or completely replace the lost 
 tissues by bringing in new blood and lymph cells and fibroblasts. 
 When the condition becomes chronic there is a tendency on the part of 
 the surrounding tissues to wall off the infectious process by the forma- 
 tion of a fibrous tissue capsule as in chronic abscesses. This is the 
 purulent type of pyorrhea alveolaris. 
 
 But when the predominating organism is non-purulent in character 
 like the streptococcus-pneumococcus group, a somewhat different 
 
GENERAL PRINCIPLES OF PYORRHEA 
 
 541 
 
 picture is presented. Against these organisms the tissue reactions are 
 of low order and less protective than the former tj'pe. As a rule, the 
 overlying gingival tissues are not highly inflamed or h^pertrophied, 
 and frequently show little pathologic change other than a slight 
 retraction. Consequently, these may easily be overlooked, especially 
 in their early stages. The deeper tissues undergo a mild form of 
 
 Fig. 420. — Pyorrhea, hypertrophic type; swelling of gum tissues ; strong tissue reactions. 
 
 degeneration and are replaced by a fibrous tissue of new order. Deep 
 peridental lesions are formed in which there is little or no pus, and in 
 the adjacent tissues many lymphocytes and plasma cells are massed 
 in an unorganized state. This form of pyorrhea corresponds in tj-pe, 
 therefore, to the periapical granulomata, in which the infectious 
 
 Fig. 421. — Pyorrhea, passive type; deep pockets about practically- all tcetli but no outward 
 signs present. No swelling; gums nearly normal in color; no inflammatory reaction. 
 
 organisms tend to penetrate the tissues and produce in them prolifera- 
 tive degenerations. It is undoubtedly in these non-purulent types of 
 peridental infection that the danger of metastatic focal infection is the 
 greatest. 
 
 The characteristic action of the different t^pes of infection and the 
 varying local and general reactions to them are reflected in the clinical 
 
542 PYORRHEA ALVEOLARIS 
 
 appearances of pyorrhea which are presented. In case the reactions 
 are of a good order, the tissue changes are clearly evident, often livid 
 in appearance^ and are readily recognized (Fig. 420). While in other 
 cases, either because of the presence of a streptococcal organism of low 
 virulence or a low state of general bodily activity the tissue reactions 
 are mild, the clinical disturbances are slight and little evidence of the 
 process is given other than a hidden and obscure pyorrheal pocket 
 (Fig. 421) . It follows that cases of pyorrhea in which the most dangerous 
 types of infection are involved and the most severe tissue destruction 
 is accomplished often escape clinical observation and no effort is made 
 to check them. In every clinical examination, careful search should 
 be made for the characteristic pyorrheal pocket and only when it is 
 determined that the gingivae are firmly attached about each tooth and 
 that no sub-gingival pockets have been formed may it safely be said 
 that pyorrhea does not exist. 
 
 Causes of Pyorrhea Alveolaris. — In a consideration of the causes of 
 pyorrhea, it is very essential that we keep clearly in mind that the seat 
 of the primary lesion is unquestionably located in the investing tissues • 
 about the teeth, which, in the course of the disease, are progressively 
 destroyed or changed in their character. Irrespective of all the con- 
 flicting theories which have been held thereto, it must be admitted that 
 as long as the normal attachment of the gingival tissue remains intact 
 about the teeth, there can be no characteristic lesion of pyorrhea. It is 
 only by the breaking of this close union of gingival tissue to the neck 
 of the tooth, that a pyorrheal pocket may be effected. If, therefore, 
 these gingival tissues could be kept in health and normal relationship 
 to the teeth which they surround, true pyorrhea would not occur. 
 
 Inasmuch as the perfection of the attachment of the gingival tissues 
 to the tooth and their resistance to infectious organisms depends 
 upon the healthy tone or pull of the peridental fibers which support 
 them, it follows that, whenever disturbances occur in the gingival 
 circulation, either from local or constitutional causes, the tissues suffer 
 from malnutrition, the tone of the fibers is lowered and the gingival 
 tissues fall away from the neck of the tooth. Thus, by reason of local 
 circulatory disturbances, the gingival crevice becomes widened and 
 patent, affording an easy access by which the oral microorganisms 
 may invade and attack the deeper tissues. Following the initial 
 invasion, the future coiuse of the infectious process depends upon 
 the type of local tissue reactions which oppose it. In one case 
 active hyperemia will be set up which may effectually protect the 
 deeper tissues from invasion, and confine the infection to the super- 
 ficial tissues, while in another case when the tissue reactions are 
 not of good order a similar injury may give rise to a rapid degeneration 
 
CAUSES OF PYORRHEA ALVEOLAR! S 543 
 
 and deep infection of the underlying peridental tissues. Because of 
 the complex nature of this process it is often difficult to determine 
 whether the various types of local disturbances to the peridental 
 circulation act as primary and exciting causes of the disease or merely 
 predispose to it by preparing the way for some other factor. But 
 clinical observation has definitely determined that when in the treat- 
 ment of these disturbances all local irritants have been completely 
 removed and the normal peridental circulation has been reestablished, 
 the course of the disease is checked, and in the majority of cases is 
 permanently arrested. In the treatment of these conditions by local 
 operative measures the relationship between cause and effect, namely, 
 the local irritants and the peridental disturbance, is so evident that we 
 are led to view the local disturbances of circulation as highly important 
 factors in the inception of pyorrhea. The causes of these disturbances 
 may be enumerated as follows : 
 
 Local Causes — Trauma of Foods. — The oral tissues are constantly 
 subjected to various forms of traumatic injury. A certain amount of 
 friction and buffeting of the teeth and surrounding tissues by the 
 mastication of hard foods seems to be beneficial to them, as it assists 
 in cleaning the mouth and stimulates the peridental circulation. But 
 when excessive and repeated pressures are brought to bear upon the 
 hard or soft tissues of the mouth, irritation and circulatory disturbances 
 are set up which result either in a hypertrophy or a degeneration of the 
 tissues depending upon the type of their reaction to the injury. Trau- 
 mata frequently occur in interproximate spaces, when the normal 
 contact has been lost and food is crowded upon the interproximate gum 
 septa during mastication. An example of the hypertrophic type may 
 be seen in Fig. 422 in which the interproximate gum is swollen as a 
 result of the crowding of food between the teeth. In Fig. 423 a similar 
 case is sho-v^ai in which the gum tissue has been destroyed and deep 
 pyorrheal pockets have been formed along the roots of the adjacent 
 teeth. 
 
 A single pyorrheal pocket may be established on the labial, buccal, 
 or lingual surface of a tooth as the result of injury by the excessive 
 excursions of food against it when the corresponding enamel surface 
 is flat or lacks normal contour. As has been pointed out (see p. 165) 
 these flat tooth surfaces usually result in a simple retraction of the 
 gum contour at that point, but it not infrequently occurs that a 
 specific rupture is made in the tissues and by subsequent infection a 
 deep pyorrheal lesion is effected (Fig. 424) . 
 
 Operative Traumata. — In the performance of various operative pro- 
 cedures the gum tissues are frequently injured. As a rule, wounds 
 of the mucous membrane heal readily, but when the resistance is low 
 
544 PYORRHEA ALVEOLARIS 
 
 infectious organisms may become implanted on the site of such injuries 
 to form a deeper lesion. For example, cutting of the gingival tissues 
 by saws, files, ligatures, bands, etc., may be followed by an infection 
 of the wound leading to the establishment of a pyorrheal lesion. Gold 
 shell crowns which are poorly fitted to the roots and extend down deep 
 
 Fig. 422. — -Interproximate trauma of Fig. 423. — Interproximate trauma of 
 
 food between molar and bicuspid, pro- food between molars, producing shrink- 
 
 ducing hypertrophy of gum tissues. ^ age of tissue and loss of gum septum. i 
 
 into the pericementum, overhanging proximate fillings and ill-fitting 
 clasps on dentures are common offenders of this type. These injuries 
 set up circulatory disturbances in the surrounding tissues by the irrita- 
 tions which they produce and if the protective reactions are not of high 
 order, infection and tissue destruction will ensue. 
 
 Fig. 424. — Retraction of gingivse on labial surface of upper and lower left centrals 
 resulting from traumata of food excursions over teeth having no labial contour. Upper 
 right central is a porcelain crown having a prominent labial contour which has effectually 
 protected the gum tissues about it. 
 
 Traumatic Occlusion. — Pyorrheal lesions may be established about 
 one or more teeth as the result of excessive or abnormal occlusion. 
 Not every case of mal-occlusion will produce such lesions, but in cases 
 in which the general health and metabolism are of low order, the 
 irritation of excessive occlusion frequently acts as a predisposing cause 
 of peridental infection. In the treatment of all cases of pyorrhea it 
 
 1 Whinney, M. A.: Dental Review, 1907, p. 611. 
 
CAUSES OF PYORRHEA ALVEOLARIS 
 
 545 
 
 has been found necessary, therefore, to correct, as far as is possible, all 
 faults of occlusion for the reason that they act as a contributory cause 
 of irritation which must be corrected before healing of the lesion may be 
 effected (see p. 168). 
 
 Trauma of Calculi. — It is a matter of common observation that the 
 great majority of cases of pyorrhea are associated with a deposition of 
 calculi on the teeth. Considerable speculation has been made as to 
 the part which these deposits play in the process. It is not clear 
 whether they are active exciting causes of the peridental disturbance 
 or are secondary depositions laid down as a result of the tissue degenera- 
 tion. Certain it is that they do act as important factors in the process 
 whenever they are present. If they impinge upon the soft tissue, 
 either externally or beneath the gum margin, 
 they will produce injury to them as the teeth 
 move in mastication. By the rough surface 
 which they present they interfere with the 
 cleansing of the mouth and tend to harbor 
 food and infectious materials about the teeth. 
 They are actively irritant in the peridental 
 tissues and constitute a contributory factor 
 to peridental disease. 
 
 Several different varieties of calculi may 
 be distinguished, which have been divided 
 by the majority of writers into two classes, 
 salivary and serumal or sanguinary. It is 
 not clear where the dividing line between 
 these two varieties of calculi may be placed 
 since all pyorrheal pockets are more or less 
 open to the saliva and there is always a pos- 
 sibility that even deposits which are formed 
 deep down on the lateral surface of the roots 
 
 may be salivary in origin. This we have shown experimentally to be 
 possible^ by producing outside of the mouth deep calculi on teeth which 
 were covered with modeling compound to simulate the gums leaving 
 narrow crevices along the lateral surfaces of the roots to form deep 
 pockets. When immersed for several weeks in a solution of calcium 
 salts, the concretions shown in Fig. 425 were produced. 
 
 Calculi vary in color, form, hardness, brittleness and the rapidity 
 with which they are built. Accumulations on the surface of the teeth 
 occur most frequently on the buccal surfaces of upper molars and 
 bicuspids opposite the opening of Stenson's duct and on the lingual 
 
 Fig. 425. — Subgingival 
 calculus formed artificially 
 on root imbedded in model- 
 ing compound with a pocket- 
 like crevice about. Labial 
 portion of modeling com- 
 pound broken away to show 
 calculi. 
 
 1 Bunting and Rickert: Journal National Dental Association, August, 1915, p. 256. 
 35 
 
546 PYORRHEA ALVEOLARIS 
 
 surfaces of the lower incisors. These deposits are self-evident and 
 easily recognized but those which are formed beneath the gum are not 
 so easily discovered. The subgingival types consist of small granules, 
 plates or scale-like rings (Fig. 90) which may encircle the necks of the 
 teeth or extend along the lateral surface of the root in a deep pyorrheal 
 pocket. They are frequently hidden from view and offer considerable 
 difficulty in removal (Fig. 426) . 
 
 Fig. 426. ^Pyorrhea with heavy subgingival calculus about roots of all teeth. 
 
 Nature and Origin of Calculi. — ^The salivary calculi on analysis are 
 found to be composed of masses of calcium phosphate and carbonate 
 built upon a mucinous or colloidal matrix and arranged in concentric 
 layers about a central nidus. The findings of Rainey and Ord^ relative 
 to the origin of biliary and urinary calculi have shed considerable light 
 on the method by which salivary calculi are formed. They found that 
 in a medium containing colloid, earthy salts were precipitated in 
 spheroidal masses which in time coalesced to form large concretions. 
 They proved that urinary and biliary calculi are formed by the precipi- 
 tation of urinary and biliary salts in colloidal materials as mucin, 
 albumin, etc. In the same manner the formation of salivary calculi 
 may be explained as a precipitation of calcium salts from the saliva in 
 the mucin and colloids present in the mouth. It has been observed^ 
 that the first step in the formation of calculi consisted in the deposition 
 upon the teeth of calco-globulin in the form of a flaky white precipitate. 
 This deposit when first laid down is soft and viscous, insoluble in water 
 but may be removed easily by the brush or finger. In time it becomes 
 hard and brittle and takes on the general characteristics of dental 
 calculi. A copious flow of this calco-globulin follows the ingestion of a 
 full meal of highly nutritious foods and is also more abundant during 
 
 1 On the Influence of Colloids upon Crystalline Forms and Cohesion, London, 1879. 
 
 2 Black, G. v.: Dental Review, 1912, p. 337, and in his Special Dental Pathology. 
 1915. 
 
CAUSES OF PYORRHEA ALVEOLAR! S 547 
 
 illness. The statement has also been made^ that salivary calculi are 
 formed as the result of fermentation processes in the oral cavity giving 
 rise to acids, notably lactic acid. The acid thus formed supposedly 
 precipitates the mucin from the saliva which in turn drags down the 
 phosphates and carbonates of calcium to form a mass upon the teeth 
 which in time hardens to form calculi. 
 
 It is evident that calculi when first laid down are soft and mucinous 
 in character, in which form they may be removed easily by the tooth 
 brush and other mechanical measures. Later they become hard a ad 
 firmly attached to the surface of the teeth from which they may only 
 be dislodged by considerable force. The rate of tartar formation in 
 the mouth is not dependent upon the amount of calcium in the saliva, 
 for we have found that the calcium content of the saliva is no higher 
 in individuals who have considerable dental calculus than in those who 
 have little. The process seems to be dependent upon the amount of 
 mucinous and colloidal matter in the saliva which when deposited upon 
 the teeth constitutes a matrix in which inorganic salts from the saliva 
 and possibly the blood are precipitated. The control of calculus 
 formation therefore may be accomplished by the limitation of calco- 
 globulin in the salivary secretion by regulation of the diet and by the 
 removal of the deposits from the teeth daily while they are soft, at 
 which time their removal may be accomplished readily by the tooth 
 brush and dental floss. Furthermore, it is a common observation that 
 when a mouth is put under a strict regime of oral prophylaxis by which 
 oral fermentations are largely decreased, the tendency to form calculi 
 is greatly diminished. 
 
 Bacteria.- — ^As we have related in the section on History, every 
 pyorrhetic lesion is infested with a variety of microorganisms of 
 which the most common forms are streptococci, staphylococci, B. 
 fusiformis, spirochete, and types of amebse. These organisms doubt- 
 less play an active part in tissue destruction and in the formation of the 
 characteristic lesions of the disease. It is usual, however, that upon 
 close study of the case some other predisposing cause, either local or 
 general, may be found which prepared the way for the bacterial invasion 
 and without which the infection would not have occurred. But occa- 
 sionally a case is presented in which no predisposing cause is apparent; 
 no calculi or other traumata are present and no constitutional fault is 
 evident. In them the active causative factor is a particularly virulent 
 type of organism which seemingly has the ability to penetrate the 
 peridental tissues unaided by any other factor. Beginning cases of 
 this type may be seen in mouths that are comparatively clean and 
 
 1 Burchard, H. H.: Dental Cosmos, 1895, p. 821, and 1898, p. 1. Also E. C. Kirk and 
 others. 
 
548 
 
 PYORRHEA ALVEOLARIS 
 
 hygienic, their only fault being a narrow plaque of bacterial growth 
 about the cervix of each tooth (Fig. 427). As a result of this growth a 
 marked gingivitis is seen about all the teeth (Fig. 428), which disappears 
 after careful and thorough prophylactic measiu-es have been performed. 
 
 Fig. 427.- 
 
 -Location of bacterial plaque with disclosing solution. Highly infective organ- 
 isms present producing gingivitis. 
 
 These cases are relatively rare and are seemingly due to the presence 
 of a highly infective type of organism, although it is possible that if our 
 clinical vision were keen enough we might discover some predisposing 
 and determining factor which inaugurates the process other than the 
 microorganisms. 
 
 Fig. 428. — Severe gingivitis, infective type, no calculus being present. 
 
 Cigarette Smoking. — ^We have observed a limited number of cases 
 of pyorrhea in which the lesions were confined to the labial surface of the 
 upper anterior teeth, the remainder of the mouth not being affected 
 (Fig. 429). In each of these cases a history of inveterate cigarette 
 smoking was obtained. The nature and location of the lesions coupled 
 with the history led us to suspect that the resistance of the labial 
 mucous tissues had been lowered by the direct action of the smoke 
 from cigarettes held in the lips. This view was supported by the fact 
 that when the cigarettes were held in a mouth-piece by which the smoke 
 was directed beyond the teeth to the interior of the mouth and prophy- 
 
CAUSES OF PYORRHEA ALVEOLARIS 
 
 549 
 
 lactic measures were instituted, the inflammation subsided and the 
 tissues healed. 
 
 Although the local causes of pyorrhea just enumerated in many cases 
 seem to be active and potential factors in the disease, the local dis- 
 turbances which they produce are profoundly modified by the general 
 and constitutional status of the body as a whole. As has been pre- 
 viously stated, a most prominent characteristic of peridental disease 
 is the inflammatory reaction by which the tissues oppose the invading 
 process. When these reactions are of high order, local irritations excite 
 strong circulatory reactions which are hypertrophic in type and are 
 strongly resistive to invading organisms. In this manner the tissues 
 successfully withstand continued indignities from local injury without 
 undergoing degeneration or disintegration. On the other hand, when 
 the local reactive powers of the affected tissues are low, rapid destruc- 
 tion and deep pyorrheal involvement may take place as the result of a 
 
 Fig. 429. — Severe pyorrhea f)n anterior teeth, associated with heavy cigarette smoking. 
 
 mild local injury. The significance of the local causes, and their ability 
 to produce peridental disease is directly dependent therefore upon the 
 protective powers of the tissues affected. As the quality of protective 
 reaction which the local tissues possess is, in turn, largely determined 
 by the general health and bodily metabolism of the individual, the 
 inception and progress of every case of pyorrhea is uifluenced and often 
 dominated by general and constitutional states. Abundant illustra- 
 tions of this fact may be seen in the differmg t}3)es of cases which are 
 presented, on the one hand, in individuals who are weak, debilitated, 
 and mal-nourished, and on the other, in those who are strong, robust 
 and full blooded. Those who are constitutionally weak are frequently 
 predisposed to pyorrheal infections which run a rapid course and 
 produce deep involvement and destruction of tissues. The stronger 
 type of individual is more often affected by gingivitis of a h;yTpertrophic 
 and proliferative order and, as a rule, shows a marked immunity toward 
 
550 PYORRHEA ALVEOLARIS 
 
 pyorrhea! invasion. When pyorrhea does occur in this latter class, 
 some other metabolic fault may often be found by reason of which 
 the natural resistance of the local tissues has been lowered. These 
 nutritional disturbances may be so slight that they escape clinical 
 observation or they may be manifest derangements which are severe 
 in type. It has been observed frequently that pyorrhea may be asso- 
 ciated with various systemic diseases, as arthritis, diabetes mellitus, 
 syphilis tuberculosis and other debilitating affections. These systemic 
 disturbances undoubtedly act as predisposing causes to peridental 
 disease by lowering the general bodily resistance against infection and 
 certain of them have a more direct causative relationship by virtue of 
 the fact that during the course of the disease various foreign and 
 irritative substances from the altered salivary secretions are laid down 
 in or upon the peridental tissues. 
 
 Systemic Causes. — Gout and Arthritis. — Among the systemic dis- 
 eases which are associated with pyorrhea, gout and arthritic affections 
 are very commonly recognized. In the course of these diseases the body 
 suffers from an excessive retention of uric acid in the blood and tissues 
 as a result of which serious nutritional and metabolic disturbances are 
 produced in all bodily tissues. As a further characteristic of these 
 affections, salts of uric acid may be deposited in certain tissues in the 
 form of crystals of sodium biurate. These deposits usually occur in 
 the articulatory joints producing gout and arthritis and may also be 
 laid down in the gingival capillaries and in the peridental membrane, 
 where they act as irritants and mechanical obstructors of the circula- 
 tion. In cases of severe arthritis, the resistance of the peridental 
 tissues to pyorrhetic mfections may be potentially lowered with the 
 result that individuals so affected are definitely predisposed to peri- 
 dental diseases. 
 
 Diabetes Mellitus. — It has been noted that diabetic patients are 
 prone to pyorrhea. The marked debility and nutritional disturbances 
 attendant upon the disease are sufficient to account for the lowered 
 resistance of the oral tissues. Furthermore, as a prominent charac- 
 teristic of the disease there is a tendency of all tissues toward infection 
 and these infections when once begun run a rapid and virulent course. 
 The mouths of diabetics are usually in a poor state of oral hygiene and 
 bacterial growth is prolific. About all the teeth there is found a pasty 
 mucous colloidal material which interferes with oral cleanliness and 
 in which the microorganisms thrive. In diabetes, therefore, the oral 
 fermentations are high, the resistance of the tissues is lowered and 
 pyorrhea! invasion is common. 
 
 Systemic Poisons. — ^Predisposition to pyorrhea may arise from 
 systemic intoxication. The source of these poisons may be the 
 
CAUSES OF PYORRHEA ALVEOLARIS 551 
 
 introduction of drugs through stomachic or subcutaneous routes, 
 the elaboration of toxins from bacterial invasion, and the production 
 of poisonous substances as the result of faulty body metabolism. In 
 the first group, perhaps the most spectacular example is that of mercurial 
 poisoning which has long been associated with oral disease and saliva- 
 tion. After a continued dosage of mercury the gum tissues take on a 
 characteristic bluish color which is diagnostic of mercurialization. In 
 the circulation of this drug through the body there is a tendency for it 
 to become lodged in the gingival capillaries where it mechanically 
 occludes the vessels and produces passive congestion and thrombosis. 
 The blue color of the gums is indicative of venous congestion in the 
 vessels which lie immediately beneath the mucous membrane. As a 
 result of profound circulatory and nutritional disturbances the resist- 
 ance of the peridental tissues is lowered and they frequently succumb 
 to pyorrhetic invasion. It has been noted, however, that if in cases 
 of mercurialization the mouth be kept clean and in a hygienic state, 
 these congestive and inflammatory conditions of the gingival tissues 
 do not occur. In explanation of this phenomenon it is claimed that 
 the deposition of mercurial salts in the gingivge is dependent upon the 
 presence in the mouth of certain products of fermentation (probably 
 sulphides), arising from the decomposition of foods. When the 
 mercuric compounds in the gingival circulation come into contact with 
 these sulphides which may diffuse through the mucous membrane an 
 insoluble compound of mercury is formed which is lodged in the 
 capillaries of the peridental tissues. When no oral fermentations 
 exist the mercury remains in solution in the blood stream and is not 
 deposited. The rationality of this premise is well supported by the 
 fact that in many syphilitic clinics in which a rigid regime of oral 
 prophylaxis is instituted for every patient large qy.antities of mercury 
 are given without producing any serious disturbance in the peridental 
 tissues. In many instances dentifrices containing potassium chlorate 
 are used. This ingredient supposedly assists in maintaining the 
 mercury in the soluble chlorid form. 
 
 A similar relationship is noted in regard to lead and other forms of 
 metal poisoning. In each case they disturb the gingival circulation 
 and lower the resistance of these tissues against infection. As a rule 
 it may be said that their deposition is largely favored by faulty oral 
 hygiene. 
 
 Auto-intoxication. — ^During the com-se of many diseases and dis- 
 tm-bances of metabolism poisonous substances are produced by the 
 body and are given off to the general circulation. These may consist 
 of waste products which the body has failed to eliminate or in abnormal 
 and harmful products of cell metabolism. Examples of this class have 
 
552 PYORRHEA ALVEOLARIS 
 
 already been cited in the cases of arthritis and gout. The condition 
 known as acidosis also should be included in this class of poisons. 
 Normally, the reaction of the blood is alkaline and the maintenance of 
 this alkalinity is of great importance to body metabolism. When by 
 disturbances of function an excess of acids is present in the blood and 
 tissues all enzyme and chemical changes in the body are disturbed. 
 Severe acidosis occurs in diabetes, cancer, after anesthetics and in 
 certain periods of pregnancy. A milder form arises from excessive acid 
 ingestion or from incomplete oxidation of foods by the body. These 
 hyperacid states are usually obscure and not easily recognized but 
 there are strong evidences that they often act as predisposing factors 
 in peridental disease and unless corrected, militate against the successful 
 treatment of the case. Under the direction of a competent internist 
 acidosis may often be relieved by prescribing a balanced diet and by 
 the administration of alkalies. 
 
 Intestinal Intoxication. — It has been noted by many writers and 
 practitioners that pyorrhea is frequently associated with constipation. 
 In addition to the ingested food and drug poisons which may be 
 absorbed from the intestine there is a class of poisonous products 
 which are formed in the intestine by the bacterial fermentation of 
 ingested food. This latter form of intoxication is, as a rule, much less 
 acute than that of drugs and food poisons. They constitute a mild 
 subacute or chronic intoxication producing changes in metabolism which 
 are not easily traced to their ultimate source. The elaboration of these 
 poisonous products and their absorption from the intestine are favored 
 by chronic constipation and obstruction or dilatation of the bowel. 
 The most significant intestinal poisons are the various split products 
 of protein decomposition, indol, skatol, phenol, ptomaines, etc., which 
 when absorbed into^the system act either as active poisons or as dis- 
 turbers of cell metabolism. In many cases when the individual has 
 followed an ill-balanced diet which is overloaded with proteins and 
 when because of sedentary occupation, lack of exercise or digestive 
 faults, the foods undergo putrefaction in the intestinal tract, rather 
 than digestion, the products of this decomposition and retained fecal 
 matter may enter the circulation to produce systemic poisoning. The 
 frequency with which pyorrhea is associated with constipation, exces- 
 sive meat ingestion and lack of exercise strongly suggests that intestinal 
 intoxication may play an active part in the inception and continuation 
 of peridental disease. 
 
 Age. — Pyorrhea seldom occurs in the young and vigorous indivi- 
 duals but is limited almost solely to those of middle or advanced age. 
 The great predominence of its occurrence in the later years of life 
 indicates that predisposition to peridental disease increases with age. 
 
CAUSES OF PYORRHEA ALVEOLARIS 553 
 
 This tendency may arise from a physiologic decadence of the peridental 
 tissues, from a general lowering of metabolic efficiency and resistance 
 of the body as a whole, or to a change in the oral secretions as a result 
 of which calculi and viscous materials are laid down upon the tissues 
 to act as local irritants or to interfere with oral hygiene. 
 
 In a consideration of the etiology of pyorrhea it must be admitted 
 that constitutional factors play a more or less important part in every 
 case of the disease; in certain instances it is only a subordinate one and 
 in others it constitutes the dominant and determining factor. As we 
 have stated previously, many operators who are successful in the 
 treatment of peridental disease have failed to observe the relationship 
 of general bodily states to the affections which they treat because of 
 the fact that by the performance of local operative and prophylactic 
 measiu-es alone they are able to arrest and control a great majority of 
 pyorrheal cases. Since the disease frequently yields to local operative 
 procedures, they conclude that it is essentially a local disturbance and 
 independent of constitutional causes. In the explanation of this 
 situation and in answer to the question which was asked in the section 
 on the Significance of Local Operative Procedures, as to the manner 
 in which pyorrhea, a systemic disease, might be controlled by local 
 measures alone, the following statements may be made: 
 
 If, as has been pointed out, pyorrhea is essentially a destruction of 
 peridental tissues by infectious organisms arising from a lowering of 
 the resistance of these tissues, it follows that any procedure which 
 will decrease the causative factors and increase the resistance and 
 combative power of the tissues will tend to arrest the progress of the 
 disease and may effect a cure. It is to this end that practically all 
 operative and oral prophylactic measures are directed. Upon the 
 removal of all traumatic and mechanical irritants, the disturbances 
 which they have produced in the peridental circulation will cease. As 
 a rule, in these cases excessively high fermentative processes predomi- 
 nate throughout the oral cavity and the bacterial life is vastly increased 
 over the normal. When prophylactic measures are completely per- 
 formed these abnormal bacterial growths are reduced to the point at 
 which they are no longer significant and the general infective pictiue of 
 the oral cavity disappears. A similar process occurs in the pyorrhetic 
 lesion. In the act of removing the sub-gingival calculi from the roots 
 by operative measures and by planing their surfaces a considerable 
 amount of infective material is mechanically removed from the tissues. 
 In this manner the tissues are relieved by mechanical irritation and the 
 bacterial flora both oral and sub-gingival are greatly reduced. Further- 
 more, in the performance of these operative procedures more or less 
 bleeding occurs as a result of which the stagnant and congested blood 
 is drained from the tissues and an active circulation is stimulated. 
 
554 PYORRHEA ALVEOLARIS 
 
 The immediate effect of local operative measm'es consists in the 
 removal of mechanical irritants, a marked decrease of infectious 
 organisms, and a stimulation of the peridental circulation. If the 
 infectious organisms be sufficiently decreased to the point where the 
 invaded tissues with their quickened and renewed circulation may 
 successfully combat the remaining organisms (complete sterility not 
 being practicable in oral tissues) the peridental disease may be arrested 
 and healing take place as the direct result of local procedures alone. 
 And in fact, this is frequently accomplished even in cases in which 
 general and constitutional factors have been largely concerned in the 
 process. In them the decrease of the attacking force and the increase 
 of resistance and recuperative power of the local tissues are able to 
 control the disease notwithstanding the general predisposing factors 
 which may exist. It is very evident that the treatment of such 
 cases will be facilitated and the chances of success greatly enhanced 
 if the general and constitutional factors involved be recognized and 
 corrected, concurrent with the local treatment. A neglect of the 
 systemic causes which lie behind these local degenerative processes" 
 frequently results in the failure and inability of local measures to 
 control the disease. 
 
 In view of this wide range of local and constitutional factors which 
 may enter into the various cases of pyorrhea it will be recognized that 
 this disease is an extraordinarily complicated and involved process. 
 As each may be the product of any or all of these causative factors, it 
 follows that almost an infinite number of combinations may be formed 
 which may militate against the health and integrity of the peridental 
 tissues. Pyorrhea, as has been previously stated, is not uniform nor 
 constant in its manifestations but presents many phases and variations 
 in its course. Success in treating and controlling these conditions is 
 dependent upon the recognition of the most predominating factors in 
 each case, and the institution of measures which will either remove 
 these determining causes or reduce them to a state of inefficiency. To 
 accomplish this a close study of the various cases which are presented 
 must be made and methods of diagnosis must be established by which 
 the various types of pyorrhea may be recognized and classified to the 
 end that intelligent treatment may be instituted to control the disease. 
 
 Diagnosis. — ^The means by which the type and severity of various 
 cases of pyorrhea may be determined consist of certain local symptoms 
 and disease manifestations associated with the state of general health 
 of the patient. The primary symptoms may be classified into four 
 definite groups namely, changes in color, form, and density of the gums 
 and their attachment to the necks of the teeth. These are supple- 
 mented by secondary or more advanced local symptoms such as the 
 
DIAGNOSIS 
 
 555 
 
 loosening of the teeth, the presence of ])us and roentgenographic evi- 
 dence, together with a consideration of the general systemic condi- 
 tions. It is by the proper interpretation of these sjinptomatic changes 
 that the various types of pyorrhetic affection may be analyzed and 
 classified. 
 
 Changes in Color. — The color of the normal gum tissues varies in 
 different individuals from light to dark shades of pink, but in all cases 
 the color is uniform tlu-oughout (Fig. 430). This color is the reflection 
 of the hemoglobin of the blood in the capillaries which lie immediately 
 beneath the mucous membranes while the depth of the color is deter- 
 mined by the amount and quality of the blood in the vessels. In full 
 blooded individuals the submucous circulation is filled with red blood 
 which gives a deep pink or dark red color to the gum tissues. In con- 
 trast to these the anemic and undernourished t^^pes have a less amount 
 
 Fig. 430. — Normal, healthy.gums. 
 
 of blood in the peripheral circulation, the hemoglobin content is usually 
 low and the color of the gum tissues is normally a light shade of pink 
 (Fig. 431). Thus we may read in the general gum color many interest- 
 ing and important facts concerning the general health and the character 
 of the general circulation. 
 
 Any localized deviation from that uniform color which is t^'pical to 
 an individual is indicative of local changes in the circulation. Darker 
 shades of red usually denote hyperemia, the depth of the color depend- 
 ing upon the severity of the circulatory distiubance. Deep red and 
 blue (Fig. 432) are indicative of stasis and passive congestion and an 
 engorgement of the submucous circulation with venous blood. These 
 localized changes in the gum color should be to the operator a signal of 
 danger for, as a result of the circulatory derangement, these tissues 
 mil suffer from a lack of nourishment and will lose their normal tone 
 and resistive power. It may also be noted that in the vicinity of these 
 
556 
 
 PYORRHEA ALVEOLARIS 
 
 color changes some form of irritant, either chemical, bacterial or 
 mechanical, may be found which is, producing an active injury, upon 
 the removal of which the color of the tissues, as a rule, promptly returns 
 
 Fig. 431. — Pale anemic gums, evidence of poor circulation. 
 
 Fig. 432. — Localized change of color between upper central incisors, deep red to purple, 
 indicative of localized irritation at that point. 
 
 Fig. 433. — Gingivae highly inflamed and congested in response to some foim of local- 
 ized irritation. Indicative of strong protective tissue reaction and as a rule responds 
 readily to treatment. 
 
 to normal. By experience one may also read in these gima colors the 
 types of protective reaction which are put forth by the tissues to com- 
 bat the injury. In those cases in which the tissues are red and give 
 evidence of strong inflammatory reaction (Fig. 433) it will be found 
 
DIAGNOSIS 
 
 557 
 
 that the pyorrheal invasion advances slowly and that when the irrita- 
 tions have been removed the tissues show a rapid recuperative power. 
 Conversely, when the guin colors are pale or dark blue (Fig. 421) the 
 reactions are less complete, the invasion is more rapid and a cure 
 more difficult to obtain. Color changes, therefore, constitute a very 
 important diagnostic factor in the discovery of pyorrhea and in the 
 evaluation of the local tissue reactions. 
 
 Changes in Form. — ^Normally the gum contour about the teeth follows 
 that of the edge of the enamel at the neck of the tooth which it slightly 
 overlaps. In the interproximate it extends up to the point of contact 
 completely filling the space between the adjacent teeth. Deviations 
 from the normal are of two types, namely, shrinkage or retraction of the 
 gum line, and swelling or h}^7)ertrophy of these tissues. Examples of 
 the former may be seen in the retretction of the buccal or lingual 
 
 Fig. 434. 
 
 -Loss of interproximate bone and gum tissues in beginning pyorrhea. 
 Reaction poor. 
 
 contours due to tooth brush abrasions or to the atrophy of old age. 
 So also, the gingival tissues are retracted as a result of deep pyorrheal 
 involvement. A slight retraction of the interproximate tissues is sho\^^l 
 in Fig. 434, and a more severe involvement in Fig. 435. Swelling of 
 the gum tissues about the teeth frequently occurs (Fig. 436) in the 
 early stages of gingivitis and pyorrhea. It is indicative of strong 
 inflammatory reaction and usually denotes a high degree of resistance 
 and recuperative power. As in the case of color changes one may also 
 read in the behavior of the gum contours the t;^^e of tissue reactions to 
 various irritations. When their tendency is to shrink and retract it 
 may be inferred that the resistance of the tissues is low and that 
 degenerative changes are easily induced. But when in response to 
 injury the tissues swell, especially if the color is bright red, the local 
 tissue reactions are usually of good order and highly resistant to 
 pyorrhetic invasion. 
 
558 PYORRHEA ALVEOLARIS 
 
 Changes in Density. — ^The normal gum tissues are hard, firm and 
 resistant to mechanical injuries. The mucous membrane is tightly 
 stretched over an underlying dense connective tissue which is sup- 
 ported by the alveolar process. This epithelium is so tough that in 
 the act of vigorous mastication and brushing of the teeth no abrasion 
 
 Fig. 435. — Extensive loss of alveolar bone and retraction of gingiva; in advanced pyorrhea 
 (case treated and under control at time picture was taken) . 
 
 or hemorrhage of the soft tissues will occur. But when the gum tissues 
 are soft, spongy, and bleed easily as the result of slight injuries they are 
 no longer normal or in health. This latter condition is indicative of 
 chronic inflammation or general bodily disturbance and tissues so 
 affected are often highly susceptible to pyorrhetic infection. 
 
 Fig. 436. — Gingivitis, hypertrophic type, indicative of strong tissue reactions. 
 
 The Line of Attachment. — ^Normally the gum tissues are firmly 
 attached about each tooth to the peridental membrane at the bottom 
 of a shallow gingival crevice. When by exploration it is determined 
 that this normal attachment has been disturbed and that a space 
 exists between the root and the surrounding peridental tissues, it is 
 evident that the tissues have suffered some form of injury which in the 
 
DIAGNOSIS 559 
 
 great majority of cases is pyorrheal in type. No matter how much 
 inflammation and swelhng may be present in the superficial and 
 gingival tissues true pyorrhea does not exist as long as the line of 
 attachment of the soft tissues about the root remains normal. The 
 crucial test of pyorrhea consists, therefore, in the careful exploration of 
 all gingival crevices to determine whether or not definite breaks in the 
 normal line of attachment have been effected. This is the most impor- 
 tant and the most certain method of diagnosing pyorrhea. 
 
 Loosening of the Teeth. — It is only in the more advanced and severe 
 cases of pyorrhea that the teeth become loosened. Because pyorrheal 
 lesions, as a rule, are confined to but one or two sides of the teeth and 
 tend to extend apically along the sides of the roots rather than about 
 them, deep lesions may be produced about teeth which still possess 
 sufficient peridental attachment to hold them securely in position. 
 When by reason of extension of the disease one or more of the teeth 
 becomes loose, it may be inferred that the condition is very serious and 
 the possibility of successful treatment of these teeth is doubtful. The 
 loss of stability on the part of a tooth may arise either from a rapid and 
 extensive destruction of the peridental membrane by which the attach- 
 ment of the root is cut off from the surrounding alveolar bone, or from 
 a disintegration, or a metaplasia of the bone to fibrous tissue by which 
 the attachment of the tooth becomes wholly fibrous and unfirm. The 
 prognosis in case of a loosened tooth depends upon the type of degenera- 
 tive process which has occurred. When there is only a moderate degree 
 of movement and by roentgenographic evidence it is determined that at 
 least the apical half of the root is embedded in bone^ if other conditions 
 permit, treatment may be attempted. But when on percussion the 
 tooth plays up and down or may be rotated in its socket, and the 
 roentgenographic findings show that the surrounding bone has been 
 destroyed, treatment, as a rule, is contra-indicated. In this latter case 
 the successful cure of the disease would involve not only the healing 
 of the lesions and a reattachment of the tissues to the teeth, but also 
 a regeneration of sufficient bone to give stability to the root. This 
 result may be obtained occasionally in young and healthy individuals 
 under most favorable circumstances, but should never be hoped for 
 when systemic derangement exists or in patients past middle life. 
 
 Pus. — The presence of pus has been used by many as an important 
 and specific means of diagnosing pyorrhea. But as we have previously 
 pointed out, pus is not a specific feature of pyorrhea inasmuch as a 
 large majority of pyorrheal lesions have no visible purulent discharge. 
 The only information that may be derived from pus is that the pre- 
 dominating organisms are of the purulent type and that against them 
 the tissue reactions are of good order. Instead of being a symptom of 
 
560 PYORRHEA ALVEOLARIS 
 
 grave significance, pus is an indication that the tissues are combating 
 the infection and perhaps controlUng it and that in view of the active 
 local reaction the prognosis of treatment of such a case is favorable. 
 
 Roentgenogra'phic Findings. — ^There are many roentgenographers who 
 claim that they are able to diagnose all stages of pyorrhea by the roent- 
 genogram, but in our experience this form of diagnosis is accurate and 
 valuable for only one phase of the process, namely, the extent of bone 
 destruction. In all other questions regarding a pyorrheal involvement 
 one may be easily misled by roentgenographic evidence; as for instance, 
 it is difficult and often impossible by these means alone to differentiate 
 between an active pyorrheal state and a healed lesion of the disease. 
 An opinion, therefore, regarding a case of pyorrhea, should never be 
 formulated from the evidence of a roentgenographic film alone, but 
 rather should all other means of diagnosis be employed in which the 
 roentgenogram is but one factor. From the roentgenogram a more or 
 less accurate idea of the amount of bone destruction may be obtained. 
 In this also there is a possible source of error in that destruction of the 
 interproximate bone may take place to produce a hole or cup-shaped 
 depression between two adjacent teeth, while the labial and lingual 
 plates are still intact, in which case the exact status of the osseous 
 lesion is not easily determined by the roentgenogram. So also the 
 destruction of bone on either the labial or lingual aspects of the tooth 
 may not be apparent when the opposite bony walls are unaffected, as 
 the shadow of the healthy portion obscures the outline of that which is 
 diseased. Too much dependence should not be placed on the roent- 
 genogram in the diagnosis of pyorrhea, but rather should it be employed 
 only as an auxiliary and a subordinate factor in the whole chain of 
 evidence. 
 
 General Considerations. — In every case that is presented the first ques- 
 tion to be determined is whether treatment should be attempted or 
 extraction prescribed. By means of the foregoing methods of diagnosis 
 accurate information may be obtained regarding the local conditions, 
 but this alone will not suffice. As we have previously attempted to 
 point out, no disease should be considered as a local process independent 
 of general and bodily states. The diagnosis and treatment of pyorrheal 
 affections should not be made without a careful and thorough con- 
 sideration of the general health, age, temperament, occupation, environ- 
 ment and personal characteristics of the patient. This is especially 
 true in those cases in which the systemic health is an active factor in 
 the disease. As a rule, treatment is contra-indicated in patients who 
 are in ill health, especially if their disabilities are of an infective type. 
 Whenever treatment is attempted in such cases the possibility of the 
 pyorrheal infections being foci of general infection should always be 
 
TREATMENT 561 
 
 clearly borne in mind and if a prompt improvement of the local and 
 general distm'bances is not obtained, all suspected teeth should immedi- 
 ately be extracted. On the other hand, if the general health is good 
 and all other conditions are favorable, many severe and advanced 
 cases of pyorrhea may be treated and the lesions successfully healed. 
 The decision concernmg the expediency of treatment of any individual 
 case of pyorrhea should be determined very largely by the general 
 systemic status of the patient and all contributing influences which 
 may help or hinder the favorable outcome of such treatment. To this 
 end many operators insist that all patients submit to a complete 
 physical diagnosis before treatment is attempted, and in many instances 
 such a course is highly desirable but in a large nrmaber of cases a fairly 
 accm-ate opinion of the general health may be obtained by a few well 
 directed questions and the general appearance of the patient. 
 
 Treatment. — Any consideration of the treatment of pyorrhea should 
 be preceded by a clear conception of what benefits may reasonably be 
 expected to result from such remedial measm-es. The statement 
 frequently has been made by many writers that pyorrhea cannot be 
 ciu-ed and this opinion still obtains in the minds of many practitioners 
 today. If by cm'e is meant the healing of the lesions of the disease and 
 the complete restoration of all lost tissues by structm-es that are 
 identical with the original tissues, it is true that severe and advanced 
 cases of pyorrhea in which a considerable portion of the ah'eolar 
 process and the overljdng tissues are lost, cannot be cured. But if a 
 permanent arrest of the disease, and a healing of the lesions by a 
 reattachment of the soft tissues about the teeth at a lower level on the 
 roots be considered a cm*e, then a large percentage of cases of pyorrhea 
 may be cured. The condition is quite similar to that of a deep ulcera- 
 tion in any part of the body which by treatment is checked but in the 
 process of healing a defect is left because of an incomplete restoration 
 of the lost tissues. In either case the disease is stopped and the lesions 
 have healed but in case the conditions which caused the first appearance 
 of the disease shall subsequently obtain, the lesions may reappear. 
 If on the contrary, ordinary hygienic measm-es be established by which 
 the causative factors are continuously removed or made ineffective, 
 the cure of the disease is permanent. 
 
 This is actually what does happen in a large majority of cases of 
 pyorrhea, when a rational treatment has been employed followed by a 
 regime of oral prophylaxis. By the complete removal of all local 
 irritants a prompt reduction of circulatory disturbances such as hyper- 
 emia, congestion and inflammation, is usualh' obtained. When, by 
 fiu-ther operative procedm*es, all denuded root sm"faces are planed 
 smooth to the bottom of the pockets the siurounding tissues usually 
 36 
 
562 PYORRHEA ALVEOLARIS 
 
 may be made to reattach themselves to the cementum, thereby com- 
 pletely obliterating the pocket. In time the soft tissues about the teeth 
 become hard, firm and highly resistant to infection and traumatic 
 injuries and as long as this state of oral hygiene is maintained the like- 
 lihood of a return of the pyorrheal infection is very remote. 
 
 Considerable skepticism has been voiced by a number of writers 
 concerning the possibility of a reattachment of the soft tissues about 
 a pyorrheal pocket to the "pus-soaked cementum" of the root. Many 
 of these writers have emphatically stated their unqualified opinion 
 that this has never occurred and that it is impossible of accomplish- 
 ment. The actual histologic proof that healing of this order has taken 
 place in a pyorrheal pocket is difficult to obtain, as patients are unwill- 
 ing to part with a tooth that has been successfully treated in this 
 manner. But clinically there is an abundance of evidence to convince 
 any fair minded and unprejudiced observer. Personally we have seen 
 cases without number, under our own care and in the hands of many 
 others, in which deep pockets freely exuding pus and extending two- 
 thirds and even three-quarters of the length of the root, in response to 
 operative measures gradually became more shallow, filling in at the 
 bottom day by day until the tissues were fully attached up to the free 
 edge of the gum margin, save a gingival crevice of normal depth. It is 
 argued by the oppositionists that this is not a true attachment but 
 merely a close coaption of the hard and soft tissues without a physical 
 union. To this we may reply that in cases in which healing has taken 
 place, if an exploration be made with a smooth nerve broach in a 
 gingival crevice at which point a pyorrheal lesion previously existed, 
 no entrance can be effected and if pressure be exerted, blood flows and 
 the patient winces from pain. There is, indeed, no example to be found 
 in any other part of the body in which the hard and soft tissues have 
 so closely coapted without physical union. Furthermore, in case of 
 implanted porcelain roots we see excellent examples of coaption of 
 tissues without physical union but in all of these an instrument may be 
 readily passed between the tooth and soft tissues at any point. We 
 recognize the fact that this perfect healing of pyorrheal lesions may not 
 always be obtained since in many cases it is not possible to completely 
 prepare all affected root surfaces or the vitality of the surrounding 
 tissues may be so low that regeneration does not take place. But we 
 are confident that when conditions are favorable and the operative 
 procedures have been completely performed, a physical reattachment 
 of the soft tissues to the root to obliterate the pyorrheal pocket does 
 take place in a large percentage of cases. When, by severe involve- 
 ment, the interproximate gum tissues and the buccal and lingual con- 
 toius have been considerably deflected, it must not be expected that 
 
TREATMENT 
 
 563 
 
 these tissues will regenerate along the root, crownwise, to assume their 
 old positions except in young individuals when the recuperative power 
 is high. As a rule, all that may be obtained is a healing of these tissues 
 and an attachment to the roots of the teeth at their present position. 
 Indeed, during the treatment, the gums may shrink down about the 
 teeth to a lower level on the roots because of a reduction of swellings 
 and circulatory disturbances (Fig. 437). 
 
 It will be recognized that the greatest success in the treatment of 
 pyorrhea is to be obtained in the early stages of the disease. At this 
 time the destruction has not been severe and if the remedial measures 
 are properly applied the disease may be checked promptly and the 
 tissues restored to approximate normality. Could all cases of pyorrhea 
 be treated in their incipient stages the handling of this disease would 
 be a simple matter. But when the process has advanced to the point 
 
 Fig. 437. 
 
 -Before and after treatment of case of advanced pyorrhea, showing retraction 
 of gingival line after reduction of peridental inflammation. 
 
 where deep lesions are effected in the peridental tissues and the alveolar 
 bone has degenerated, the treatment is much more complicated and 
 the chances of success greatly reduced. In the treatment of these 
 more advanced cases care should be taken not to attempt the impos- 
 sible. When the general health and bodily resistance are low or indica- 
 tions of severe general infections are present all seriously affected teeth 
 should be extracted at the outset. Seldom is it advisable to attempt 
 treatment of lesions which extend more than two-thirds of the distance 
 to the apex of the root. Treatment is also ill-advised when the tooth 
 plays up and down in its socket or may be rotated by pressm-e. So 
 also, when by roentgenographic evidence it is determined that there is 
 not sufficient bone remaining about the apex of the root to support the 
 tooth, successful treatment cannot be hoped for except in very young 
 and favorable individuals. 
 Treatment of pyorrhea, therefore, should be attempted only after a 
 
564 ■ PYORRHEA ALVEOLARIS 
 
 careful prognosis has been made, taking into account the extent of the 
 local destruction, the type of local reaction, and the age, general health 
 and the probable cooperation of the patient in carrying out the oral 
 hygienic measiu-es. When conditions are favorable, highly satisfactory 
 results may be obtained by proper operative and prophylactic measures; 
 but when the attending conditions are unfavorable or the disease is too 
 far advanced, attempted treatment is certain to result in disappoint- 
 ment and failure. 
 
 The method of treatment of those cases of pyorrhea which in the 
 light of careful diagnosis show promise of a satisfactory result, is largely 
 that of the application of the principles set forth in Chapter III and the 
 extension of these procedures to include the surfaces of the roots which 
 have been denuded of their normal pericemental attachments. It must 
 be recognized that in all cases of pyorrhea the general bacterial flora of 
 the mouth is abnormal and the first step in the process is to decrease 
 and change the t^-pe of oral fermentations. To this end thorough and 
 rigorous prophylactic measures should be employed to rid the mouth 
 of all foreign and harmful agencies. All calculi and foodstuffs should 
 be removed from the crowns of the teeth and between the teeth, and 
 all rough enamel surfaces should be smoothed so that they may be kept 
 clean. It is advisable to remove all ill-fitting crowns and bridges 
 which irritate the soft tissues or tend to harbor food materials beneath 
 them. All fillings which overhang their margins should be trimmed 
 down until they are flush with the enamel surfaces. In case of proxi- 
 mate fillings which do not have proper contacts with the adjacent 
 teeth the defect should be remedied or the filling replaced. All open 
 cavities should be filled, if not permanently at least with a temporary 
 stopping. 
 
 When these general prophylactic measures have been carefully 
 performed, the next step should be that of equalizing occlusal stresses 
 of all the teeth. By the use of carbon paper the points of greatest 
 stress may be located and by judicious grinding with stones any undue 
 and excessive stress of one tooth upon another may be relieved. In 
 this manner teeth which are severely affected by pyorrhea may be 
 lightened of their occlusal load and the stress of mastication shifted 
 back to other teeth which are more able to bear the burden. This 
 feature of the process is highly important to the successful treatment of 
 the disease. When all of the foregoing procedures have been carried 
 out the mouth and teeth are ready for the special treatment of the 
 pyorrheal lesions. 
 
 This treatment should consist in suitable operative procedures by 
 which the denuded cemental surfaces may be completely cleansed of 
 all calculi and foreign materials and subsequently planed to a smooth 
 
TREATMENT 
 
 505 
 
 homogeneous surface. It nuist l)e remembered that the outer surface 
 of the cementum is rough and pitted by reason of the apertures in which 
 are embedded the broken ends of the peridental fibers. If the outer 
 cemental surface be allowed to remain, its pitted surface offers an 
 admirable retention for bacterial growths, the organisms, thriving 
 like cave dwellers in the side of a cliff from which they come forth at a 
 future time to attack the surrounding tissues. If by careful planing 
 this outer pitted surface be slightly reduced, a deeper and more homo- 
 geneous layer is reached which offers little retention to infectious 
 organisms. But in the reduction of this surface great care must be 
 exercised not to cut too deeply, for the cementum on the lateral surface 
 of the root is thin and with little effort a sharp instrument improperly 
 
 D 
 
 A — 
 
 B 
 
 ^sn^^ ^esssm . 
 
 ^■:\A. :r ^ 
 
 *• ' 
 
 
 iiMi!ij.yiiii;, ...... ,..,-..• jjiii 
 
 Fig. 438. — Cross-section of root carefully smoothed with files. D, dentin; T, granular 
 layer of Tomes; C, cementum; 4, portion of cementum not touched with files; B, portion 
 of root filed, showing removal of cementum and cutting into the dentin. 
 
 applied will cut through the cementum and the homogeneous layer which 
 lies below into the granular layer of Tomes on the periphery of the dentin 
 (Figs. 438, 439 and 440). When this unfortunate result has occiu-red 
 the surface so cut can never be made smooth but will be deeply pitted 
 by spaces opening directly into the dentinal tubuli in which the pyor- 
 rheal infections may find a permanent habitation to prevent the success- 
 ful healing of the lesion. It is therefore of the highest importance 
 that in the operation of preparing the root surfaces too much cementiun 
 should not be removed, but rather should these surfaces be carefully 
 and evenly smoothed until by the sense of touch transmitted through 
 the instrument it is determined that a homogeneous siu^face has been 
 obtained and then all further reduction at that point should cease. 
 This operation may be accomplished by the various types of instru- 
 
566 
 
 PYORRHEA ALVEOLARIS 
 
 ments described on p. 153 which should be used in the manner outHned 
 for preventive dentistry. In each case an instrument should be selected 
 
 D. 
 
 iV- -•• 
 
 — H'^-. 
 
 > ■"•1 
 
 f 
 
 Fig. 439. — Cross-section of root smoothed with Younger type of instrument. D, dentin ; 
 T, granular layer of Tomes ; C, cementum which has not been appreciably reduced by 
 the instrumentation. 
 
 which best adapts itself to the position upon the root it is desired to 
 reach and then the blade should be carefully introduced beneath the 
 
 Fig. 440. — -Cross-section of root smoothed with planing instruments. D, dentin; 
 T, granular layer of Tomes ; C, cementum ; A , portion of root not touched with the planers ; 
 B, portion of root planed, showing reduction of cementum nearly to cemento-dental 
 junction. 
 
 gum to the bottom of the pocket to plane the surface of the root with 
 a draw motion, crownwise, until the root is smooth. 
 
TREATMENT ' 567 
 
 The operative treatment of pyorrhea should not be done in a hit or 
 miss manner but should follow a consecutive plan of procedure which is 
 directed toward a definite object to be attained. This object is the 
 surgical cleansing and smoothing of every surface of each denuded 
 root and the reduction of the infective organisms to the point that the 
 resistance of the tissues may gain ascendency over them. To this end 
 the operative procedures should begin in one corner of the mouth, for 
 instance the last upper right molar, and progress tooth by tooth about 
 the mouth until all are surgically clean. Each tooth should be finished 
 before another is attempted and if the surfaces are properly prepared 
 it should not be necessary to do any further instrumentation upon 
 them other than the cleansing of the pockets as will be described later. 
 
 In view of the fact that this form of treatment is a careful exacting 
 operation and is more or less painful to the patient it is always wise to 
 make the appointments short, not more than thirty to forty-five minutes 
 to be repeated each successive day, treating but two or three teeth at 
 each sitting until all have been covered. In cases of highly infective 
 type in which the tissue resistance is low the treatment of only a few 
 teeth is a distinct advantage. It is noted that operation upon these 
 highly infective types of pyorrhea frequently is followed by a distinct 
 shock. As a result of the operative procedures the protective tissue 
 wall about the infection is broken down and through the surgical 
 wounds that are produced a quantity of infectious organisms and their 
 products are introduced directly into the circulation. Consequently, 
 fever and general bodily disturbances may follow drastic treatment 
 of too many pyorrheal lesions at any one sitting. When only a few 
 such lesions are operated upon, the general effects are usually less 
 marked or are insignificant. 
 
 When a surgeon operates in a sterile field he closes the wound and 
 does not disturb it unless infection subsequently sets in. But when the 
 wound is on a surface that necessarily must be reinfected and cannot 
 be kept sterile, he washes and dresses the wound daily until healing 
 has taken place. Operations on pyorrheal tissues are of this second 
 type, in that the wound is constantly open to oral infections, food 
 materials, and other foreign substances which irritate the tissues and 
 miHtate against their healing. 
 
 Of special significance in this regard are the fine subgingival calculi 
 which are laid down upon the roots of teeth in a pyorrheal lesion 
 subsequent to operation upon them. It is frequently noted that 
 although the root-surfaces may have been thoroughly planed and 
 smoothed at one sitting, the next day a new deposition of calculi may 
 be found beneath the gum line which will continue the irritation to the 
 surrounding soft tissues and prevent their healing. The som-ce of 
 
568 PYORRHEA ALVEOLARIS 
 
 these rapidly forming calculi is not definitely known, but it is probable 
 that they are an inflammatory exudate of the diseased tissues. When 
 by prophylactic measures the peridental inflammation has been 
 reduced and the tissues have assumed their normal color and density 
 this tendency to form subgingival calculi is terminated. It is therefore 
 necessary at each daily sitting to go about the teeth which have pre- 
 viously been treated and carefully enter the pockets to remove any 
 foreign materials and infectious matter from them, extreme caution 
 being taken not to tear down the new peridental attachments which 
 have been formed in the process of healing. This may be done with a 
 small Younger type instrument or with dull files, after which the pocket 
 should be flushed with a bland solution. When this procedure is carried 
 out daily it will be seen that day by day the instrument may be intro- 
 duced a shorter and shorter distance beneath the gum until finally no 
 pocket remains, healing having been completely accomplished from the 
 base of the lesion up to the gingival line. 
 
 Thus as the result of instrumentation alone in favorable cases the 
 pus fiow may cease after one treatment and by daily cleansing and 
 washing a complete attachment may be effected between the teeth and 
 the peridental tissues. As an adjuvant to these measures the pockets 
 may be flushed out with a weak iodin or a saline solution. The follow- 
 ing iodin lotion is admirable for this purpose as it is antiseptic, sedative, 
 astringent and stimulative in its action. The formula is as follows: 
 
 Phenol (5 per cent.) 1 part 
 
 Aconite (tinct.) 2 parts 
 
 Iodin (tinct.) 3 " 
 
 Glycerin 4 " 
 
 This may be introduced into the pockets with a glass barreled syringe 
 having a platinum point which may be sterilized readily in the flame 
 (Fig. 441). In many cases a 5 per cent, sodium chlorid solution will 
 give equally beneficial results. This strength is to be preferred over 
 the bland physiologic salt solution for the reason that the hj^pertonic 
 salt in contact with the tissues produces in them an exosmosis and 
 exudations which tend to wash the mucous surfaces. Furthermore, 
 the lymph and blood fluids are in this manner attracted to the spot 
 bringing many germicidal and immune principles to aid in the reduction 
 of infection. 
 
 It is the opinion of the author that no other drugs are necessary in 
 the treatment of pyorrhea except in rare cases. Occasionally an old 
 tough granulation tissue will be found about a chronic pyorrheal 
 pocket and when such a tissue obstinately refuses to heal after proper 
 instrumentation, it may be treated with phenol-sulphonic acid (Merck) . 
 
TREATMENT 569 
 
 This may be introduced into the pocket by means of a thin wedge made 
 of bamboo held in a porte-pohsher. 
 
 As heahng takes place, the patient may be seen less and less fre- 
 quently. During this time he should be instructed in the proper 
 method of caring for his mouth, encouraged to keep the tissues con- 
 tinuously clean, and to massage the gums with the brush until they are 
 hard, firm and highly resistant. When the case is finally under control 
 and the pockets healed, the patient should be requii'ed to report at 
 intervals of from one to three months, depending upon the case, in 
 order that he may be assisted in the care of his mouth and that all 
 incipient gum lesions may be noted early in their course. Usually 
 these lesions may be easily aborted in their incipiency by the removal 
 of the irritation which has caused them and as a result, the tissues are 
 readily restored to normal health. In certain types of cases when the 
 lesions have healed and the infections have been eradicated, the 
 
 Fig. 441. — Syringe for washing out pyorrheal pockets. 
 
 tissues remain permanently in health and no tendency to recurrence 
 is evident. But in other types, especially when the saliva is thick and 
 mucinous, the mouth hygiene is not easily maintained, infections are 
 high and the tissue resistance is low. There is in them a constant 
 tendency toward a recurrence of the pyorrheal invasion^ for the pre- 
 vention of which it is necessary to combat continuously the predisposing 
 factors wdiich are present. 
 
 Thus we see that the successful treatment of a given case of pyorrhea 
 depends upon the severity of the case, the reaction of the local tissues, 
 the generak health, and the thoroughness with which the operative 
 procedures are performed. Provided that the first three of these con- 
 siderations are favorable the degree of success is largely determined 
 by the perfection of technic which is employed in the sm'gical pro- 
 cedures. Half way measures are worse than none, for they cause 
 pain and discomfort to the patient and result only in failure. But 
 
570 
 
 PTOHRHEA ALTEOLARIS 
 
 careful and conscientioTis study of these conditions and the technic 
 involved to relieve them vrill enable the oi)erator to obtain a permanent 
 healing and a x>otential cure of a large majoritj" of such favorable 
 
 Fig. m; 
 
 rrheal mvotvemeiit vith deep 
 rei "witli tlifn scales of Iiard, 
 11-; recoTered after ocirplete 
 
 Fie. 
 
 -- r - nptly recoTered after tltorciiighi operaave pro- 
 
 L T::ream(i aft^: 
 
 izz lecoT-ay fottowing operative treatmer: 
 
TBEATJtEXT 
 
 571 
 
 A soies of eases wijidi Imxe been tpmted in ti*e maiDUQier wlakii iaas 
 beem ootjiiied, is shown in Fig^- 412 to 451 iniAiMve. "Haese cases hare 
 been sdected hoaa. the cdl^ie dime and fecMii pnvate pcactice, ilie 
 
 Fbs, 155 . — Case ©f ae^rese 
 
 ihmra griggnra afffrgsr ii«iHMa«wf^iMS.- ^® S^ri^eisms (i€ 
 
 iise. -sAt. — (Las? r; srTjr 
 Teass affttor Ereaiiiffliieiiii- E;~ 
 
 
 within a few weds ol eacli :" 
 to e#ect a conqJete core buE 
 
572 
 
 PYORRHEA ALVEOLARIS 
 
 ment in the clinical appearance of the case, the pyorrheal invasion had 
 been stopped, the lesions were healing and the case was e^'idently under 
 
 Fig. 448. — The Ht. Family — Father. Before and after treatment. Severe involve- 
 ment, upper central incisor extracted, case under control one year later. Pictures taken 
 one month apart. 
 
 Fig. 449. — -The Ht. Family — Mother. Before and after treatment. Severe pyorrhea with 
 mal-occlusion. Case under control one year later. Pictures taken one month apart. 
 
 Fig. 450. — -The Ht. Family — Daughter, aged twenty-one. Before and after treat- 
 ment. Incipient pyorrhea which promptly yielded to treatment. Pictures taken one 
 month apart. 
 
 control. Many of them when kept under prophylactic supervision for 
 some time continued to improve and much of the tissue which had been 
 
PERICEMENTAL ABSCESS 
 
 573 
 
 lost in the course of the disease was restored by the heahng process. 
 Other cases which passed out of supervision for over one year were 
 still in good condition and showed little or no evidence of active 
 P3'orrheal invasion. Figs. 445, 446 and 447 are pictures of finished cases 
 of some five or six years' standing which originally had suffered from 
 severe pyorrhea but which had shown no recurrence of that disease 
 since the original operative treatment. Figs. 448, 449, 450 and 451 are 
 interesting as they were taken from the members of one family, namely, 
 father, mother and two daughters, aged twenty-one and fourteen 
 respectively. Both father and mother had severe cases of pyorrhea, 
 although not of the same type and both daughters showed beginning 
 pyorrheal involvement of a type like that of the mother. 
 
 Fig. 451. — The Ht. Family — Daughter, aged fourteen. Tendency toward peridental 
 disease similar to elder sister. 
 
 PERICEMENTAL ABSCESS. 
 
 In comparatively rare cases, abscesses are formed on the lateral 
 surfaces of the roots of teeth which are seemingly unrelated to the 
 apical or gingival areas. They occur on teeth in which the pulps and 
 periapical areas are normal and may or may not be associated with 
 pyorrhea. Two general classes of pericemental abscesses may be 
 distinguished: first, those which are situated on roots of teeth which 
 have been attacked by pyorrhea and which are virtually deep extensions 
 of pyorrheal lesions some distance down the side of the root, and second, 
 those which apparently are unaccompanied by any other peridental 
 disease. In their course they may be marked by extensive inflamma- 
 tory changes and swelling or they may develop in a gradual insidious 
 manner without pain or other outward evidence of their presence. 
 When they are purulent in type, the pus may burrow its way to the 
 surface along the peridental membrane and be evacuated in the gingival 
 crevice or a pyorrheal pocket, or it may penetrate the overlying 
 submucous and mucous tissues to form a fistula on the lateral surface 
 
574 PYORRHEA ALVEOLARIS 
 
 of the gum after the manner of periapical abscesses. It is difficult to 
 differentiate abscesses of the first type from true pyorrheal lesions 
 and the latter type may be easily confused with true periapical abscess. 
 On the surface of the root corresponding with the initial point of abscess 
 formation the pericementum is denuded and usually a deposit of thin 
 plate-like calculus may be fomid firmly adherent to the cementum. 
 The source of these deposits and the deep infection in these peridental 
 tissues is not clear. Pierce^ found that many of the calculi answered 
 to the murexid test for urates from which he concluded that they were 
 laid down by the general circulation as the result of a uric acid diathesis. 
 Kirk^ found that in a number of cases which he examined the infection 
 involved was a pure culture of pneumococcus. In many cases perice- 
 mental abscesses seem to be deep and penetrating forms of pyorrheal 
 invasion in which the infection having burrowed into the tissues some 
 distance beyond the apparent lesion, has produced at its farthest exten- 
 sion an acute exacerbation of tissue destruction accompanied by 
 calcareous deposit. In other cases they occur on the roots of vital 
 teeth about which there is no evidence of pyorrheal involvement. 
 This latter form has been thought to arise from systemic or constitu- 
 tional cause which may be associated with various local traumatic 
 injuries such as malocclusion, excessive stress, accidents, etc. Indeed 
 they seem to occur with greater frequency in individuals who suffer 
 from certain systemic distm-bances as gout, diabetes, Bright's disease, 
 and other like affections. More recently it has been found^ in cases 
 of faulty oral hygiene when oral fermentations are high that micro- 
 organisms, especially the streptococcal type may penetrate deep into 
 the pericementum without producing an apparent lesion. In view of 
 this fact, it is possible to conceive that all pericemental abscesses may 
 arise as the result of invasion of infectious organisms from the gingival 
 crevice when the resistance of the peridental tissues against them is of a 
 low order."* 
 
 The lesions formed by pericemental abscesses may be extensive, 
 involving a considerable portion of the peridental membrane. The 
 prognosis of these affections is extremely unfavorable especially in 
 individuals who are suffering from constitutional or nutritional dis- 
 turbances. In the favorable case, if the root be freed of calculi and 
 carefully planed, slow healing may take place. The author has in 
 
 1 International Dental Journal, 1894, p. 1. 
 
 2 Dental Cosmos, 1900, p. 1149. 
 
 ' Collins and Lyle, in the Journal National Dental Association, April, 1919, p. 370, 
 state that they have found abundant evidence that periapical infection may arise from an 
 extension of infected organisms from diseased gingival tissues. 
 
 ■* Roys claims that every case of pericemental abscess has a twisting, serpigenous tract 
 by which it communicates with the gingival crevice and that it is along this tract that 
 the infection enters the deep pericemental tissues. — Dental Cosmos, 1918, p. 659, 
 
VINCENT'S ANGINA 
 
 575 
 
 mind a case of pericemental abscess situated at the bifurcation of the 
 roots of a lower first molar, in which healing was successfully accom- 
 plished in this manner and the bone which was involved largely regen- 
 erated as was showTii by roentgenograms taken one year apart (Figs. 452 
 and 453) . But many cases are presented which do not respond to the 
 most careful operative technic and which persist in a state of active 
 infection and suppuration as long as the tooth remains in position. 
 For them the only remedy is extraction. 
 
 Fig. 452. — Rueutjienofirumof perice- 
 mentai abscess at bifurcation of roots of 
 lower molar, showing destruction of 
 alveolar bone. 
 
 Fig. 453. — Roentgenogram of case 
 shown in Fig. 452, one year after treat- 
 ment by curettage, showing bone regen- 
 eration. Lesion healed. 
 
 VINCENT'S ANGINA. 
 
 Certain ulcerative affections of the oral tissues frequently may be 
 confused with, and often erroneously diagnosed as, pyorrhea. Of these 
 perhaps the most common t}^e is a spreading diphtheria-like lesion 
 which usually begins in the pharjoix from which it spreads to the oral 
 tissues. The specific organisms of this affection were identified by W. D . 
 Miller in 1883 as the fusiform bacillus and an accompanying spirochete. 
 Later Vincent more fully described the disease since which time it has 
 been known as Vincent's Angina. He classified the lesions as belonging 
 to two groups as follows: 
 
 A. "The superficial, pseudo-membraneous or diphtheroid form in 
 which a thin grayish white film usually starts over one tonsil and 
 gradually spreads, often over a wdde area. Usually the membrane is 
 easily removed, though not en masse, leaving a red bleeding base and a 
 shallow ulceration. There is generally an associated diffused pharyn- 
 gitis. 
 
 B. "The ulcerative, and more common form, in which there is deep 
 tissue necrosis, covered by a thick, creamy, yellowish or gray exudate, 
 which comes away easily and again leaves a raw, granular, bleeding 
 base. This leads to the formation of crater-like ulcers mth irregular, 
 somewhat indurated and undermined edges." 
 
576 PYORRHEA ALVEOLARIS 
 
 This description' is fairly comprehensive with the exception that the 
 ulceration is not confined to the pharynx but rather does it frequently 
 spread to the tissues of the oral cavity on which it produces its charac- 
 teristic lesions. Diuing the late war it occurred as an epidemic among 
 the troops in a highly infective and contagious form, spreading through- 
 out the camps and hospitals with great rapidity. Here it was known 
 as "trench mouth" or "trench gunis."^ 
 
 Vincent's angina usually begins with a sore-throat and a diffused 
 pharyngitis following which a thin white membrane spreads over the 
 surface of the fauces which may or may not be accompanied by definite 
 ulcerative lesions of the pharyngeal tissues. From this region the white 
 film is extended toward the oral cavity which it encompasses by spread- 
 ing along the buccal gums and gingival areas toward the anterior part 
 of the mouth. In various locations ulcers may occm* which form a 
 creamy exudate, upon the removal of which a raw bleeding surface is 
 revealed. These affections light up rapidly and exhibit a high degree 
 of bacterial overgrowth so that within a few days all the tissues of the 
 mouth may be involved by the inflammatory and ulcerative process. 
 It is noted, however, that the patient is never as ill as the condition 
 of the mouth might seem to warrant. Seldom does the temperature 
 rise over 101° but in severe cases the patient suffers from extreme 
 depression, pain in joints and loss of appetite. The author observed 
 one case, that of a soldier, who refused to eat for two weeks. As the 
 result of his fasting, combined with the severe Vincent infection, the 
 patient became extremely emaciated and was for sometime in a very 
 precarious condition. 
 
 In the mouth Vincent's angina may be recognized by a general 
 inflammation of all the oral mucous membranes, accompanied by a 
 characteristic white, pseudo-membrane on the gum tissues and deep 
 ulcerations filled with white creamy exudate. The bacteriologic find- 
 ings of material taken from the lesions reveal a mixed culture of 
 organisms in which the fusiform bacillus and its accompanying spiro- 
 chete greatly predominate (Fig. 454). Two forms of the B. fusiformis 
 have been described, one a Gram-negative organism which has flagellse 
 and is motile, the other Gram-positive and non-motile, having a tendency 
 to clump.2 The bacilli appear thickened in the middle and pointed at 
 both ends. They are always associated with a large spirochete with 
 which they live in symbiotic relationship. These fusiform-spirochete 
 cultures are anaerobic in type under which conditions they have been 
 isolated and grown on artificial media. On the tissues they are associ- 
 ated with extensive ulcerations, but show no tendency to infiltration 
 
 1 Barker and Miller: Jour. Am. Med. Assn., September 7, 1918. 
 
 2 Hartzell: Journal National Dental Association, 1917, p. 477. 
 
VINCENTS ANGINA 
 
 577 
 
 or metastasis. The relationship of these two organisms to Vincent's 
 angina is not clear. Although they are always present in its lesions 
 and disappear as they are healed, artificial production of the disease 
 by inoculation of fusiform bacillus and spirochete cultures has never 
 been accomplished. Moreover these organisms are frequent inhabi- 
 tants of healthy mouths in which no evidence of Vincent's disease is 
 apparent. This is especially true when the oral hygiene is poor and 
 fermentations are high. But although accurate proof of the specificity 
 of these organisms has not been forthcoming, the consensus of opinion 
 today is in support of the view that the fusiform bacillus and its accom- 
 panying spirochete are at least essential factors in the production of 
 Vincent's disease. 
 
 Fig. 454. — Fusiform bacillus and spirochete from case of Vincent's angina. i 
 
 Although these conditions are severe in their course and present 
 clinical pictures which are startling and alarming, they usually may be 
 controlled and promptly arrested by the employment of relatively 
 simple remedial agencies. In the great majority of cases the mouth 
 hygiene has been faulty and quantities of food and other deposits are 
 lodged about the teeth in which the infectious organisms are thriving 
 in a high state of virulence. By simple prophylactic measures alone 
 the infective process may be greatly reduced and many times it may 
 be completely eradicated in this manner, no other treatment being 
 necessary. To be effective, however, these prophylactic measm-es 
 must be completely and carefully executed. All foreign matter must 
 
 1 Simon in Adami and McCrae's Text-book of Pathology. 
 
 37 
 
578 PYORRHEA ALVEOLARIS 
 
 be removed from about the teeth and the gingival crevices. Special 
 attention should be given to those localities which, by mechanical 
 retention, offer breeding places for the Vincent organisms. In pyor- 
 rheal pockets and beneath the gum flap about partially erupted third 
 molars, the organism may be retained to reinfect the mouth and bring 
 on a recurrence of oral infection unless special attention is given to 
 these areas. In addition to prophylactic measures a variety of thera- 
 peutic agents have been suggested for the control of the infection. 
 Local applications of iodin, silver nitrate (10 per cent.), chromic acid 
 (5 per cent.), zinc sulphate, hydrogen peroxid, wine of ipecac. Fowler's 
 solution, salvarsan and arsphenamin, are recommended by various 
 authorities as well as the systemic administration of arsphenamin and 
 fusiform-spirochete inoculations. All writers agree that mercury in all 
 forms is contra-indicated in these conditions as the drug tends to in- 
 crease the virulence of Vincent's angina and actively interferes with 
 its control. 
 
 The following method has been used successfully by the author in a 
 large number of cases : 
 
 Swab the mucous membrane of the mouth and pharynx with cotton 
 saturated with H2O2, in this manner mechanically remove the white 
 pseudo-membrane. 
 
 Superficial oral prophylaxis, care being taken not to injure the soft 
 tissues. 
 
 Cleanse ulcerative lesions and remove slough with cotton swab 
 saturated with silver nitrate (10 per cent.), or argyrol (25 per cent.). 
 
 Swab the mouth with iodin lotion (p. 161). 
 
 Instruct the patient to rinse the mouth every three hours with 
 hydrogen peroxide (1 per cent.) followed by potassium permanganate 
 0.5 per cent, and swab mucous membrane with cotton to remove the 
 infective film. 
 
 If the lips are cracked and peeling they may be painted with tincture 
 of iodin. 
 
 At subsequent sittings the oral prophylaxis should be completed as 
 soon as the condition of the soft tissues will allow. Swab with iodin 
 lotion. 
 
 These measures should be continued until all evidences of inflamma- 
 tion have disappeared. 
 
 Finally, all residual nests of organisms should be eradicated. 
 Diseased tonsils and impacted or partially erupted third molars are 
 favorite breeding grounds, which frequently must be removed to per- 
 manently control the infection. 
 
 In a great majority of the cases a careful performance of these 
 measures will result in the immediate improvement of the diseased 
 
RETRACTION OF THE GUMS 
 
 579 
 
 tissues and a rapid return to health, complete recovery even of 
 severe cases frequently occurring in a few days or a week (Fig. 455). 
 When the infection still persists for some time after treatment, or 
 periodically recurs after a temporary abatement, it is very probable 
 that either the prophylactic measures have been incompletely per- 
 formed or some hidden breeding ground exists from which the mouth is 
 continually being reinfected. When Vincent's disease is associated 
 with pyorrhea the treatment is not so simple a matter and complete 
 eradication of the specific organism cannot be accomplished without 
 concurrent treatment and obliteration of the pyorrheal lesions. 
 
 Fig. 455. — Before and after treatment of a case of severe Vincent's angina. 
 
 taken six weeks apart. 
 
 Pictures 
 
 RETRACTION OF THE GUMS. 
 
 In this connection we should consider certain conditions which 
 result in the shrinkage and retraction of the gum tissues about the 
 teeth and which are often erroneously considered as pyorrhea alveo- 
 laris. It is a matter of common observation that the gingival margins 
 about the teeth may be retracted exposing more or less of their roots 
 without the formation of subgingival pockets. The process is essen- 
 tially that of a deflection of the gingivae, apically, along the roots of the 
 teeth, the remaining peridental tissues appearing quite like the normal. 
 This retraction of the gum may take place about one tooth, or may 
 occur about several or all of the teeth in the mouth. These changes 
 in the gingival contour are not due solely to shrinkage of the gum 
 tissues, but are associated with degenerative changes in the alveolar 
 crest of bone by which the bone is reduced in size and the overhing 
 gum tissue and gingivae sink down with it exposing the cementum of the 
 root to which the free border of the gum is firmly attached. Since no 
 subgingival pockets are formed these lesions are not pyorrheal in t^-pe 
 and should not be confused with that condition. They occur in 
 several different forms which may be grouped as follows: 
 
580 
 
 PYORRHEA ALVEOLARIS 
 
 Senile Atrophy. — In individuals past middle age the gum margins 
 frequently are retracted from the normal positions on the tooth and a 
 portion of the cementum is exposed. In these cases the crest of alveolar 
 bone has undergone senile atrophy, and as a result, the gums and 
 gingivse on all sides of the teeth gradually settle down to lower and 
 lower levels about the roots. A very similar condition may arise in 
 earlier years from a premature or precocious senility of the individual. 
 If the mouth and teeth are kept clean and free from irritating agents 
 senile degeneration of the peridental tissue takes place slowly and is 
 of little significance other than that it may be followed by sensitivity 
 of the root surfaces and an unsightly appearance of the teeth. 
 
 Traumatism. — ^A similar retraction of the gum tissues on the buccal 
 and labial surfaces of the teeth frequently occurs as the result of 
 excessive and improper tooth-brushing. When the teeth are brushed 
 
 Fig. 456. — Severe labial recession from tooth brush abrasion. 
 
 vigorously in a cross-wise manner undue stress is placed upon the 
 gingivae with the result that degenerations may take place in the under- 
 lying tissues and the gingival border is retracted. These lesions occur 
 at the site of the irritation and are usually associated with a lesion 
 in the enamel of the tooth due to tooth brush abrasion (Fig. 456) . 
 
 Triaumatic retraction of the gum tissues about the teeth may be 
 produced also by the encroachment of calculi on the gingivse by 
 operative procedures, crowns, fillings, etc., and by the abnormal 
 excursions of food in mastication. Examples of the latter are seen in 
 cases in which the normal proximate contact of the teeth is lost by 
 reason of which food is habitually crowded between them in mastication 
 and the interproximate gum tissues are severely injured (Fig. 106). 
 So also in those cases in which the teeth do not have a proper buccal 
 or lingual contour the gingivse may be accidentally torn in the act of 
 biting some hard substance and future irritations of food may continue 
 
RETRACTION OF THE GUMS 
 
 581 
 
 the retraction for a considerable distance down the side of the root 
 (p. 167). If the oral hygiene be poor, these forms of traumatic gum 
 retraction may develop into true pyorrheal lesions at the site of injury 
 and they should always be considered as factors predisposing to that 
 disease (Fig. 457). In the case of tooth-brush abrasion, a correction 
 
 Fig. 457. — -Severe labial recession on lower right cuspid from the traumata of food and 
 
 pyorrheal involvement. 
 
 of the manner of brushing the teeth will usually suffice to prevent 
 further recession of the gum. Retractions from the traumatism of 
 calculi and irritations of food, fillings, etc., may be arrested in their 
 progress by a careful and complete removal of the irritant or a correc- 
 tion of faulty tooth contours, but the lesion which has already been 
 
 Fig. 458. — Before and after treatment of case of Vincent's angina showing regeneration 
 of interproximate gum tissues in bicuspid region. Two pictures six months apart. 
 
 accomplished usually remains as a permanent defect. In acute cases 
 in which the alveolar bone is not seriously affected, a removal of the 
 irritant may result in a regeneration of the interproximate gum tissues, 
 but rarely are they replaced on the buccal or lingual surfaces of the 
 teeth. 
 
582 , PYORRHEA ALVEOLARIS 
 
 Ulcerative Gingivitis. — Occasionally a rapidly growing superficial 
 type of infection may produce an ulceration of the free margins of the 
 gums by which they are eroded and retracted. The fusiform bacillus 
 in Vincent's angina frequently produces lesions of this type. The 
 interproximate tissues suffer most severely, becoming inverted while 
 the labial and lingual borders are retracted to expose the cementum. 
 By careful prophylactic measures and the establishment of oral hygiene 
 these ulcerations may be promptly arrested and if they have not 
 progressed far enough to seriously affect the alveolar bone the eroded 
 gum tissues usually will be regenerated and restored to their normal 
 form (Fig. 458). 
 
 Healed Lesions of Pyorrhea. — ^Following the successful treatment of 
 pyorrhea it will be found that, as a rule, the gum tissues have shrunken 
 about the teeth. This is due to the fact that in the removal of the 
 peridental irritations the gingival circulation is stimulated, congestion 
 and inflammatory derangements are abated, and the swollen tissues 
 shrink to their normal thickness. Since in the process of the disease, 
 the underlying bone tissues have degenerated and decreased in size 
 the overlying gum tissues which cover them will consequently fall away 
 from the neck of the teeth and attach themselves to the roots at a line 
 farther apically than is normal. It follows, therefore, that in all cases 
 of severe pyorrhea, when as the result of successful treatment the 
 peridental tissues have become attached to the roots and the subgingival 
 pockets obliterated, a new gingival line will be formed which will be 
 retracted from the normal position (Figs. 435 , 437, 447 and 448) . These 
 post-pyorrheal gum retractions if properly cared for and kept free from 
 excessive irritations form permanent attachments to the cementum and 
 constitute the most effectual approach to healing of pyorrheal lesions. 
 
CHAPTER XIV. 
 
 EXTRACTION OF TEETH AND OTHER SURGICAL 
 PROCEDURES. 
 
 By CHALMERS J. LYONS, D.D.Sc. 
 
 Surgical Anatomy. — To extract teeth successfully, the operator should 
 be m possession of a thorough knowledge of the anatomy of the teeth 
 and surrounding parts m order that the forces in the line of least 
 resistance may be applied intelligently. The relation of the teeth to 
 the maxillary sinus, the character of the bone, the importance of the 
 canine eminence, the canine fossa, and the surfaces of the bone in the 
 upper jaw, as well as the relation of the teeth to the inferior dental 
 canal, the positions of the mental and mandibular foramina, together 
 with the study of the character of bone and the relation of the teeth to 
 the coronoid process in the lower jaw, are all matters which will be 
 great aids in the success of the operation of extraction of teeth. 
 
 The Relation of the Teeth to the Maxillary Sinus. — "Because of the 
 close anatomical relation of the maxillary sinus with the tooth germs 
 and the roots of the permanent teeth, it is evident that the sinus must 
 be more or less influenced by them. As the teeth develop and descend 
 into their normal position, the sinus increases in size. If a tooth situ- 
 ated near the sinus be retarded in its eruption, the development of the 
 sinus is interfered with at that particular point. "^ Fig. 459 shows how 
 closely the apices of the teeth may be associated with the maxillary 
 sinus. Particularly is this true with the first and second bicuspids and 
 first molars. In rare cases the apical end of the root of the cuspid and 
 the second and even the third molar may encroach upon the antral 
 cavity. Infection about the roots of these teeth may, and frequently 
 does, give rise to morbid conditions in the maxillary sinus. 
 
 In the extraction of the upper first molar, care should be exercised 
 that a portion of the floor of the antrum is not fractured away during 
 the operation. The roots of this tooth passing up on both sides of the 
 antral cavity predispose to such an accident. In the extraction of the 
 roots of the upper bicuspids the same care should be exercised that 
 they are not forced through the floor of the maxillary sinus in the 
 endeavor to engage them in the forceps. 
 
 1 Cryer: Internal Anatomj- of the Face. 
 
 (583) 
 
584 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 Character of the Bone of the Maxillse. — ^The alveolar process of both 
 upper and lower jaws consists of an outer and inner plate of dense 
 cortical bone. Between these two plates are the sockets for the roots 
 of the teeth. The sockets are surrounded by a very thin layer of 
 cortical bone, and the remaining portion of the alveolar process between 
 the outer and inner plates is filled in with cancellated or spongy bone. 
 Running through this cancellated or spongy bone are fine canals for 
 nerves and bloodvessels, the remaining portion of it being connective 
 tissues. The surfaces of the outer and inner plates have no definite 
 line of demarcation between the maxillse proper and the alveolar 
 
 Ostium 
 maxillare 
 
 First molar 
 
 Fig. 459. 
 
 First molar 
 
 -(Cryer.) 
 
 process, but continue from the cervical margin over on the maxillse 
 and are lost on the outer and inner surfaces of these bones. The 
 alveolar process is covered with muco-periosteum, which is thick and 
 dense and contains mucous glands. This covering is commonly known 
 as gum tissue. The bone proper is covered with true periosteum. Fig. 
 460 shows the anterior view of a normally articulated skull. It may 
 be seen that the central incisors are in close proximity to the suture 
 which unites the right and left maxillse. This is important knowledge 
 for the operator when extracting under local anesthesia. (See Chapter 
 XII.) The outer plate covering the lateral incisors is very heavy 
 because the labio-lingual diameter of the lateral incisors is less than 
 
CANINE EMINENCE 
 
 585 
 
 that of the teeth on either side. T]ie outer i)late of the ah^eolar i^rocess 
 is deflected from the cuspid tooth over on the central incisor tooth. A 
 depression results from this deflection and forms the incisive fossa. 
 
 Fig. 460. — Anterior view of the typical skull. (Cryer.) 
 
 The Canine Eminence. — In viewing the anterior surface of the skull 
 we may observe a heavy bony structure extending over the cuspid 
 teeth (the canine eminence). This varies in thickness in individuals 
 
586 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 and must be taken into consideration in the extraction of the cuspid 
 teeth. 
 
 The Canine Fossa. — ^The canine fossa marks the thinnest part of the 
 outer plate of the superior maxilla and forms the outer wall to the 
 maxillary sinus. This plate is extremely thin in old age and in such a 
 case great care should be exercised in the extraction of the bicuspids 
 and molars, that this surface be not injured and the antral cavity 
 exposed. 
 
 The Infra-orbital Foramen. — ^This foramen, through which the infra- 
 orbital nerve emerges on the face, lies above the canine fossa. It 
 becomes an important landmark in the use of conduction anesthesia 
 for the extraction of the anterior teeth. (See Chapter XII.) 
 
 Fig. 461. — Zygomatic surface of superior maxilla. 
 
 The alveolar process of the superior maxilla is less dense than that 
 of the inferior maxilla, which condition usually renders extraction of 
 teeth less difficult than in the inferior maxilla. 
 
 The posterior or zygomatic surface of the superior maxilla assists 
 in the formation of the spheno-maxillary fossa and presents the tuber- 
 osity, which is a rounded prominence above the third molar tooth 
 (Fig. 461). This part of the superior maxilla contains innumerable 
 fine canals for the accommodation of the nerve and bloodvessels. The 
 tuberosity varies in size in each individual and may vary on the two 
 sides of the jaw in the same individual. 
 
 Palatine Surface. — ^The landmarks on the palatine surface of the 
 superior maxilla which should be observed in the extraction of teeth, 
 are the foramina of scarpa which are located one centimeter distal to 
 the central incisor teeth and the posterior palatine foramina which are 
 located about one centimeter toward the median line from the upper 
 
INFERIOR MAXILLA 
 
 587 
 
 third molar teeth (Fig. 462). The nerves and vessels supplying the 
 hard and soft palates emerge at these points. 
 
 Fig. 462. — ^Anterior portion of the base of a typical skull. (Cryer.) 
 
 Inferior Maxilla. — ^The exterior of the bone and landmarks of the 
 inferior maxilla or mandible should be studied by the operator. The 
 alveolar process of this bone being more dense than that of the superior 
 maxilla, extraction of the teeth will be more difficult. 
 
 Mental Foramen.^Ahout five millimeters below the bicuspids and 
 two millimeters in front of the second bicuspid the mental foramen 
 may be found (Fig. 463). This point is considered the weakest point 
 in the mandible and fractures of the jaw through this area are more 
 common than at any other point. Posterior to the mental foramen 
 the alveolar process becomes very dense and heavy, consequently 
 the lower molars are usually more difficult to extract than any of the 
 
588 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 other teeth. Also, on account of the density of the alveolar process, 
 infiltration anesthesia for extraction of teeth in this region becomes 
 less satisfactory. (See Chapter XII.) 
 
 
 V„^,,,|ii»i 
 
 Fig. 463. — The right side of the lower portion of face. (Cryer.) 
 
 J 
 
 Mandibular Foramen. — On the inner surfaces of the mandible on 
 a line with the occluding surfaces of the teeth and about half-way 
 between the coronoid and condyloid processes, there is an important 
 foramen (the mandibular) (Fig. 464) . This foramen marks the entrance 
 of the inferior dental nerve and vessels into the mandible. Arising 
 from the body of the mandible are two processes, the one in front 
 being the coronoid, and the one behind, the condyloid process. 
 Arrested development of the inferior maxilla will result in the crowd- 
 ing and impaction of the teeth. In the process of development of the 
 mandible, room for the normal eruption of the first, second, and third 
 molars is provided by the physiologic absorption of the anterior 
 surface of the coronoid process. Not infrequently a pathologic con- 
 dition arises which interferes with this process of development and 
 this knowledge is necessary for the operator iii determining the degree 
 of force and direction of the application of it in the extraction of the 
 inferior teeth. 
 
INDICATION AND CONTRA-INDICATION FOR EXTRACTION 589 
 
 Indication and Contra-indication for Extraction. — ^The conditions which 
 should govern the practitioner in determining the indication and 
 contra-indication for the extraction of teeth are so varied that it is not 
 practicable to formulate any hard and fast rules that will apply in all 
 cases. Not only the local conditions but the general systemic condi- 
 tions of the patient must be considered in determining whether or not 
 the teeth should be extracted. There seems to be quite a diversity of 
 opinion at this time as to the exact status of pulpless teeth. Some 
 operators go so far as to state that all pulpless teeth are a menace to the 
 welfare of the patient and that such teeth should be extracted; others 
 believe that under certain conditions pulpless teeth can be made safe 
 if properly treated and that the patient will be able to retain them 
 indefinitely. In view of the recorded data on this subject, it would 
 
 Fig. 464.- — Inner surface of the inferior maxilla. (Cryer.) 
 
 seem that in determining the indication or contra-indication for the 
 extraction of such teeth the physical condition of the patient and the 
 strategical importance of the teeth, respectively, should be the deciding 
 factors. Some of the most important causes which demand extraction 
 of the teeth are as follows : 
 
 1 . INIolar teeth which have lost their occluding teeth in the opposite 
 jaw and are partially exfoliated from their alveoli and are becoming a 
 source of annoyance. When such a condition occurs in the bicuspid 
 region, the vacant space in the opposite jaw should often be filled with 
 an artificial tooth to prevent the exfoliation of the natm'al tooth. 
 
 2. Multi-rooted teeth with chronic alveolar abscesses, when Roent- 
 genographic evidence shows disease and death of the pericemental mem- 
 brane in the apical area. In single-rooted teeth this condition ma}^ be 
 
590 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 taken care of by apicoectomy/ provided the physical resistance of the 
 patient indicates it. Extraction is indicated in any single-rooted 
 tooth wherein there is evidence of disease or death of the pericemental 
 membrane extending over more than the apical third of the root. 
 Such a condition would preclude the possibility of saving the tooth by 
 apicoectomy. 
 
 3. Malposed teeth which cannot be corrected by orthodontic 
 measures so as to become useful. 
 
 4. Pulpless teeth with constricted or crooked canals which will 
 prevent their proper treatment. 
 
 5. Teeth in which the pulps are encroached upon by pulp stones and 
 cannot be properly treated. 
 
 6. Unerupted teeth which are apparently lying dormant in the jaws 
 or where they are causing a dental cyst. The possibility of these teeth 
 giving rise to morbid conditions always makes their removal desirable. 
 
 7. Lower third molars which are partially erupted and are causing 
 the surrounding tissues to be impinged upon by the occluding teeth, 
 so that inflammation results periodically. 
 
 8. A tooth that is partially or completely impacted and is impinging 
 upon another tooth may be the seat of extreme nervous disturbances 
 with manifestations remote from the impacted tooth; an impacted 
 tooth that is causing partial resorption of the tooth upon which it is 
 impinging; and an impacted tooth that is the seat of a periodical 
 inflammatory process. 
 
 9. When preparing a mouth for an artificial denture, the removal of 
 sound healthy teeth may be indicated for the purpose of making a 
 more efficient denture. 
 
 10. Teeth which have become loosened by any inflammatory process 
 to such an extent that a considerable portion of the alveolar process 
 has been lost. This condition may be applied to roots that have 
 supporting crowns and bridges that have become loosened due to some 
 pathologic condition. 
 
 11. Deciduous teeth which are retained after the time of their normal 
 exfoliation and are preventing the eruption of the permanent teeth. 
 
 12. Abscessed deciduous teeth which will not respond to treatment 
 and are a menace to the health of the patient. It will sometimes 
 tax the judgment of the operator to choose the right method of pro- 
 cedure in these cases. If the tooth be extracted before the normal time 
 for the eruption of the permanent tooth, mal-occlusion may result; if 
 not extracted, the patient's health may be impaired. 
 
 13. Supernumerary teeth that are of no particular value and are 
 interfering with the normal eruption of the permanent teeth. 
 
 ' This subject is treated fully at the end of the chapter. 
 
CONTRA-INDICATIONS FOR THE EXTRACTION OF TEETH 591 
 
 Contra-indications for the Extraction of Teeth.- — A careful examination 
 of the whole mouth should be made before extraction of any of the 
 teeth is begun so that a needless sacrifice of tooth function will not be 
 made. The demand that a tooth be extracted should not be taken into 
 consideration, because a patient's knowledge of mouth conditions is 
 necessarily limited, and the patient is not capable of judging the value 
 of the tooth in question. The operator's judgment should always 
 prevail. ]\Iany times a small cavity in an otherwise perfectly normal 
 tooth may be causing the patient considerable pain, and the patient, 
 not placing the proper importance on the tooth, may request its 
 removal. It should be considered bad practice to accede to the 
 patient's wishes in these matters unless by so doing the patient's future 
 welfare will be better taken care of. The operator should decline to 
 remove a tooth that is of any value to the patient. The patient's 
 futiue welfare must always be uppermost in the operator's mind when 
 determining the indications and contra-indications for the extraction 
 of teeth. Some of the most important contra-indications for the 
 extraction of teeth are as follows : 
 
 1. Often when preparing a mouth for an upper or lower denture, 
 certain teeth, such as upper or lower cuspids that are in good alignment, 
 will help to retain the artificial denture and should not be extracted. 
 
 2. With patients of advanced age who have lost bicuspids and 
 molars, where there has been marked resorption of the alveolar pro- 
 cesses and the remaining teeth are worn down by mechanical abrasion, 
 it is sometimes a debatable question whether the patient's welfare ^dll 
 be better taken care of by extraction, or by leaving the teeth in the 
 mouth and depending upon the abraded surfaces for mastication. 
 In such cases, artificial dentures are not usually very satisfactory. 
 
 3. The extraction of a tooth is contra-indicated in patients who have 
 organic heart lesions such as valvular insufficiency, hj^Dertrophy, and 
 fatty degeneration. The shock from extractions in such cases may 
 result fatally to the patient. When it is necessary to extract teeth 
 under such conditions, the patient's physician should be present. 
 
 4. In cases of abscessed teeth, which are to be extracted when the 
 operator is assured that the abscess can be evacuated by the removal 
 of the tooth, extraction is always a safe procedure. But in certain 
 other cases of acute alveolar abscess where there is extreme cellulitis 
 and the patient is suffering from septic intoxication, when the proba- 
 bilities are that the extraction of a tooth will not evacuate the 
 abscess, and the possibilities are that the extraction of a tooth will 
 turn septic intoxication into septicemia, extraction is contra-indicated. 
 In these cases palliative treatment should be instigated and continued 
 until normal conditions are reestablished. 
 
592 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 5. Often in partially unerupted third molars the gum tissue over- 
 lying the occluding surface of the third molar will become bruised as a 
 result of mastication, and an irritation will be set up which will later 
 cause an inflammatory process followed by trismus. It is good prac- 
 tice to treat the condition and allay the inflammatory process before 
 extracting the tooth. 
 
 6. When a patient with a history of profound bleeding presents for 
 extraction, great care should be exercised against extracting too many 
 teeth at one time. Whenever possible a general treatment should be 
 instituted. The administration of calcium lactate in ten-grain doses, 
 three times per day for three or four weeks preceding the operation will 
 sometimes yield good results. These patients should be put under 
 the care of a physician before extraction of the teeth. 
 
 7. In all cases of pregnancy the operation should be postponed, if 
 possible. In cases when it is necessary to remove one or more teeth 
 for the comfort of the patient, it should be done under the order, and 
 if possible, in the presence of the family physician. 
 
 8. The shock of extraction of teeth for epileptics may bring on an 
 attack. When it is necessary to extract teeth for these patients, 
 they should be watched following the operation. Should an attack 
 follow, the patient should be laid in a comfortable position with 
 plenty of fresh air, and the condition should not be considered 
 alarming. 
 
 Other conditions may arise where the judgment of the operator may 
 be taxed to the utmost in order to determine the right course to pursue. 
 The present general health of the patient, the resistance of the patient 
 to disease, the question of the patient's future welfare following 
 the sacrifice of a tooth are all factors that must govern the operator in 
 determining the operative procedure. The operator should endeavor 
 to make a judicious diagnosis in every case. In many cases a complete 
 physical diagnosis by a physician may be necessary to complete the 
 chain of factors which must be considered in determining the indications 
 and contra-indications for the extraction of certain teeth. 
 
 Management of the Patient During the Extraction of Teeth,^ — There 
 is probably no minor operation in surgery that the average patient 
 looks upon with so much fear and dread as that of the extraction of a 
 tooth. The patient comes into the office in a nervous condition, and 
 the first duty of the operator is to get the patient's mind in a con- 
 dition for the operation. With young children it is bad practice to 
 promise a painless operation when the operator knows that he cannot 
 do it. These children will be the future patients, and once their 
 confidence in the dentist is lost, it is sometimes hard to regain. The 
 operator should never manifest nervousness before his patient. If the 
 
EXTRACTION OF INDIVIDUAL TEETH 593 
 
 operator feels absolute confidence in his own ability, this will be 
 imparted to the patient. 
 
 Position of Patient. — ^The patient should be made as comfortable in 
 the chair as possible, and should then be placed in a position with the 
 principal object of securing a good view of the affected tooth and the 
 surrounding parts. The position of the patient and operator will 
 vary slightly for the extraction of each tooth. The tooth to be operated 
 upon should be in full view of the operator, and the head of the patient 
 in such a position that it can be steadied and controlled by the left arm 
 and hand of the operator. The modern dental chair is the best appara- 
 tus obtainable upon which the operation can be made. At times it 
 may be necessary to extract teeth while the patient is in bed or on an 
 operating table. In such cases, the position of the patient may not 
 always be the most desirable one, and the operator will have to adjust 
 his position to meet the requirements. When operating on a table, 
 the best position for the operator is at the head and a little to the right 
 side. The position of the patient and operator will be taken up in 
 detail in the description of extracting individual teeth. 
 
 Extraction of Individual Teeth. — ^We will first consider extraction of the 
 superior teeth. As a rule, this operation is not so difficult as the 
 extraction of the inferior teeth, for the reason that the superior teeth 
 are more accessible and the alveolar process is not so dense. The 
 forceps are the principal instruments used in the extraction of superior 
 teeth. Occasionally chisels, elevators and drills may be used to 
 advantage in the removal of roots and unerupted and impacted teeth. 
 
 The position of the operator when operating on the superior teeth 
 is to the side and slightly to the front of the patient's head when 
 extracting on the right side, and a little in front of this position when 
 extracting those on the left side. The order of extraction may be made 
 a matter of preference with the operator. Usually the field of opera- 
 tion can be kept in sight better if he proceeds from the anterior to the 
 posterior, first on the left, then on the right side. The position of the 
 patient for operating on the superior teeth should be erect and the 
 patient raised in the chair to such a height that the patient's head comes 
 just below the shoulder of the operator after the chair has been tilted 
 slightly back. The head may be turned from one side to the other as 
 conditions will require. Usually all of the teeth can be extracted 
 without changing the adjustment of the chair after it is once made. 
 
 Extraction of Superior Central Incisor. — ^Fig. 465 shows position of 
 operator and patient for the removal of superior central incisors. 
 The left arm of the operator is placed upon the head of the patient 
 with the palm of the hand over the left cheek. The upper lip is raised 
 to show the field of operation with the index finger. The second finger 
 38 
 
594 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 is used as a retractor for the purpose of retracting the cheek. The 
 palm of the hand and remaining fingers support the jaws. This 
 position of the hand and arm enables the operator to hold the patient's 
 head securely during the operation. The forceps usually employed in 
 the extraction of superior incisors are those shown in Fig. 479. The 
 forceps are adjusted to the labial and lingual surfaces of the central 
 incisor and forced upward under the free margin of the gum to the 
 edge of the alveolar process. The handles of the forceps are then 
 
 Fig. 465 
 
 gripped firmly and by the force of rotation slightly to the left, then to 
 the right, the tooth is loosened from its attachment and by a slight 
 force of traction the tooth is lifted from the socket. The forceps 
 should be adjusted in a direct line with the long axis of the tooth. If 
 this is not done, fracture of the tooth may result. 
 
 Extraction of Superior Lateral Incisor. — ^This tooth is much smaller 
 than the central. Its root is somewhat more flattened and sometimes 
 curved. The apex of the tooth often curves distinctly toward the 
 
EXTRACTION OF INDIVIDUAL TEETH 
 
 595 
 
 cuspid. The position of the patient and operator is practically the 
 same as for the extraction of the central incisor. The same forceps 
 may be used, and should be adjusted in the same manner as that 
 described in the extraction of the central incisor. The forces used are 
 slight rotation, a little pressure labially and lingually,. and slight 
 traction. The neck of this tooth is sometimes restricted to such an 
 extent that some precaution must be exercised that it is not fractured. 
 
 Fig. 466 
 
 Extraction of Suyerior Cusjnd. — Fig. 466 shows the position of the 
 patient and the operator for the extraction of the superior cuspid on 
 the right side. Fig. 467 shows the position of the patient and the 
 operator for the extraction of the superior cuspid on the left side. This 
 tooth is one of the most difficult teeth in the upper jaw to extract on 
 account of its thickness labio-lingually and the length of its root, and con- 
 siderable force is often required to break up its attachment on account 
 of the density and thickness of the alveolar process surrounding it. The 
 position of the patient is the same as for the extraction of the central 
 and lateral incisors. The position of the operator when extracting 
 on the right side is slightly back of the position for the central and 
 lateral, and when extracting on the left side it is slightly in front of 
 
596 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 this position. The same forceps are used for the extraction of the 
 cuspids as for the lateral and central incisors, and are applied to the 
 tooth in a similar manner, care always being taken to force the forceps 
 well up under the gingival margin. The forceps should be grasped with 
 much more firmness than is required for the extraction of the central or 
 lateral incisor. Pressure labio-lingually applied with an out-and-in 
 motion and at the same time slightly rotating will usually break up the 
 attachments. Slight force of traction is then used to remove it from 
 its socket. The cuspid next to the lower third molar is more often 
 
 Fig. 467 
 
 impacted or unerupted than any other. The details of the operation 
 for the removal of unerupted and impacted cuspids will be taken up 
 under the subject of unerupted and impacted teeth. 
 
 Extraction of Bicuspids. — Superior first and second bicuspids. Fig. 
 468 shows the position of the patient and the operator for the extraction 
 of superior bicuspids on the right side. Fig. 469 shows the position of 
 the patient and the operator for the extraction of superior bicuspids 
 on the left side. The technic of the operation for the extraction of 
 the first and second superior bicuspids is practically the same. 
 
EXTRACTION OF INDIVIDUAL TEETH 
 
 597 
 
 Fig. 468 
 
 Fig, 469 
 
598 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 The position of the patient in the chair, and that of the operator is 
 practically the same as that described for the extraction of the cuspid 
 tooth. The main difference is in the position of the patient's head; 
 when operating on the right side, the patient's head should be turned 
 to the left, and when operating on the left side, the patient's head 
 should be turned slightly toward the operator. The forceps used for 
 this operation are those shown in Fig. 479. The movements used in 
 the extraction of the bicuspids are to the buccal and lingual, for the 
 purpose of loosening its attachment. In exerting such force more 
 
 Fig. 470 
 
 pressure should be exerted to the buccal than to the lingual for the 
 purpose of springing the external plate of the alveolar process. After 
 the attachments are loosened the force of traction should be used. On 
 account of the shape of the roots of the first and second bicuspids, the 
 force of rotation should never be used because it may result in fracture 
 of the roots. 
 
 Extraction of Superior First and Second Molars. — Fig. 470 shows the 
 position of the patient and the operator for the extraction of superior 
 molars on the right side. Fig. 471 shows the position of the patient and 
 
EXTRACTION OF INDIVIDUAL TEETH 
 
 599 
 
 the operator for the extraction of superior molars on the left side. 
 The technic for the operation of extracting the first and second molars, 
 is practically the same and will be given together. For extraction of 
 superior molars the relative position of patient and operator is similar 
 to that for extraction of superior biscuspids. The forceps used are 
 two in number, one for the right side, and the other for the left side. 
 These are shown in Figs. 480 and 481. 
 
 The beaks of the forceps should be adjusted to the tooth in line with 
 its long axis and forced well up under the free margin of the gum, 
 
 Fig. 471 
 
 sufficiently so that the point of the buccal beak passes between the 
 buccal roots. The force used in this operation is pressure first to the 
 buccal, then to the lingual then with an in-and-out motion the tooth 
 may be loosened from its attachment. Here again greater pressure 
 should be brought to bear on the buccal so that the buccal plate may 
 be sprung slightly outward, thus loosening the tooth from its attach- 
 ment. Then again because of the shape of the roots of the molar 
 teeth, it is not practicable to bring a great deal of pressure to the 
 lingual on account of the long lingual root which would oppose pressure 
 in that direction. After loosening the tooth from its attachment. 
 
600 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 slight force of traction is used to dislodge it. On account of the shape 
 and number of the roots, the force of rotation should never be used 
 since there is danger of fracturing one or more roots. 
 
 Extraction of Superior Third Molars. — ^The position of the patient and 
 the operator will be the same as that for the extraction of the first and 
 second molars. The forceps used may be the same or may be especially 
 designed for superior third molars as shown in Fig. 482. The normal 
 superior third molar is usually not a difficult tooth to extract on account 
 of the porosity of the alveolar process surrounding it. The roots are 
 usually fused together. The forceps should be adjusted well up under 
 
 Fig. 472 
 
 the gingival margin and the forces used should be pressure buccally and 
 lingually applied with an in-and-out motion, and with a slight rotation 
 to the buccal with more pressure brought to bear on the buccal than the 
 lingual, the force of traction being used for the purpose of removing the 
 tooth. Occasionally the roots of these teeth are spread widely apart 
 and in these cases extraction becomes more difficult. In some cases 
 the gum tissue is very adherent to the distal surface of the upper third 
 molar and great care should be used not to lacerate the soft tissues 
 when extracting this tooth. 
 
EXTRACTION OF INFERIOR TEETH 
 
 601 
 
 Extraction of Inferior Teeth. — As a general rule, the extraction of the 
 inferior teeth is attended with more difficulties than that of the superior 
 teeth, since they are less accessible to the operator, and their surround- 
 ing tissues are more dense. The tongue also may sometimes interfere 
 with the operation. The position of the patient is different from that 
 for the extraction of the superior teeth. Fig. 472 shows the position 
 of the patient and the operator for the operation of extracting the 
 inferior incisors. The head of the patient should be much lower than 
 
 Fig. 473 
 
 for the extraction of the superior teeth. The operator should stand 
 at the back and slightly to the right of the patient. The patient's head 
 should be straight in the head-rest. The left arm of the operator is 
 placed around the patient's head with the palm of the hand supporting 
 the lower jaw. The fingers of the left hand are used to retract the lips. 
 In the application of the forceps to the tooth, the same general principles 
 should govern the extraction of an inferior tooth as those governing the 
 extraction of a superior tooth. The beaks should be in line with the 
 
602 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 long axis of the tooth at all times. When all of the inferior teeth are 
 to be extracted, the central incisor should be extracted first, then all of 
 the teeth on the left side distally to the molars, and then beginning at 
 the right lateral incisor, all the teeth distally to the molars on the right 
 side. Then the molars first on the right, then on the left should be . 
 taken in their order. The lower jaw should have firm support by the 
 left hand of the operator. The jaw itself being movable, some difficulty 
 may be experienced in holding it rigid while the operation is in progress. 
 
 Fig. 474 
 
 Extraction of Individual Teeth. — Extraction of inferior lateral and 
 central incisors. As the inferior central and lateral incisors are very 
 similar in shape and size, the technic for their removal will be described 
 together. Usually these teeth are not very difficult to extract, their 
 roots being slightly conical in shape. Slight rotation may be indicated 
 combined with pressure to the labial. These movements will loosen 
 the attachments. Then by the force of traction the tooth may be 
 removed from the socket. Occasionally the root of the lateral incisor 
 may be curved slightly to the distal, in which case much rotation would 
 have a tendency to fracture it. Such a tooth is removed in the line of 
 least resistance, and pressure toward the cuspid may be used. The 
 lorceps used are those shown in Fig. 484. 
 
EXTRACTION OF INDIVIDUAL TEETH 
 
 603 
 
 Extraction of Inferior Cuspid. — ^This tooth is usually more firmly set 
 in the jaw than the incisors. The process surrounding the tooth is 
 heavier, the roots of the tooth are longer and heavier than the lateral 
 or central incisors. The position of the patient and operator is 
 practically the same as for the extraction of the lateral and central 
 incisors. Fig. 473 shows the position of the patient and the operator 
 for extracting the inferior cuspid on the right side. Fig. 474 shows the 
 
 Fig. 475 
 
 position of the patient and the operator for extraction of the inferior 
 cuspid on the left side. The application of the forceps is the same as 
 for the lateral and central incisors. The tooth is loosened from its 
 attachments by the application of pressure to the buccal with slight 
 rotation. It is then removed from the socket by the force of traction. 
 The forceps used are those shown in Fig. 484. 
 
 Extraction of Inferior Bicuspids. — ^Fig. 475 shows the position of the 
 patient and the operator for the extraction of inferior bicuspids on the 
 
604 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 right side. Fig. 476 shows the position of the patient and the operator 
 for the extraction of inferior bicuspids on the left side. The forceps 
 used are those shown in Fig. 484. The technic for the extraction of the 
 first and second bicuspids is practically the same. The roots of these 
 teeth are somewhat flattened and sometimes bifurcated. The same 
 forceps are used for the extraction of the lower bicuspids as for the six 
 anterior teeth. The position of the patient and the operator is similar 
 to that for the six anterior teeth. The force of pressure to the buccal 
 is usually sufficient to break up the attachments, after which the force 
 of traction may be used to remove the tooth from its socket. 
 
 Fig. 476 
 
 Molars. — ^Extraction of inferior first molar. Fig. 477 shows the 
 position of the patient and the operator for the extraction of inferior 
 molars on the right side. Fig. 478 shows the position of the patient 
 and the operator for the extraction of inferior molars on the left side. 
 When all the teeth are in position, the first molar is a somewhat diffi- 
 cult tooth to extract on account of the widely diverging roots. When 
 operating on the left side, the patient's head should be turned slightly 
 to the right, and when operating on the right side, the patient's head 
 should be turned slightly toward the operator. The forceps used are 
 
EXTRACTION OF INDIVIDUAL TEETH 
 
 605 
 
 those shown in Fig. 485. These forceps are universal and can be used 
 on either side. The beaks of the forceps should be adjusted to the 
 tooth in the same manner as in the extraction of the anterior teeth, 
 with the points of the beaks well down under the free margin of the gum 
 and resting between the mesial and distal roots. The forces used are 
 considerable pressure to the buccal, and traction to remove the tooth 
 from its socket. These forces will usually break up the attachments. 
 Great care should be exercised in the extraction of the first molar so 
 
 Fig. 477 
 
 that the mesial root does not engage the second bicuspid and thus 
 remove this tooth at the same time. 
 
 Extraction of Inferior Second Molar. — ^The inferior second molar is 
 not so difficult to extract as the inferior first molar since the roots are 
 not so diverging. The position of the operator and the patient is the 
 same, and the application of the forceps and forces used in extraction 
 are similar. 
 
 Extraction of Inferior Third Molar. — The conditions involving the 
 inferior third molars are so varied that a definite technic for their 
 
606 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 removal cannot be given readily. The roots of a normal third molar 
 are usually curved slightly to the distal, and for such teeth the Leclues 
 elevator (Fig. 487) is a very satisfactory instrument to use for their 
 removal. The point of the elevator should be inserted into the inter- 
 proximate space between the second and third molars, using the alveolar 
 process at the cervical line as a fulcrum, and by a rotary force break up 
 the attachment. The removal of the abnormal lower third molar will 
 be taken up under a separate heading and the technic will be described. 
 
 Fig. 478 
 
 Extraction of Deciduous Teeth. — In the extraction of deciduous teeth, 
 the principles involved are the same as those applied in the extraction 
 of the permanent teeth. One of the principal features to observe in 
 the extraction of deciduous teeth is that the developing permanent 
 teeth be not injured in the operation. This is particularly true in the 
 removal of deciduous molars whereby the oncoming permanent bicuspid 
 teeth may be injured or may be removed in the operation of extraction 
 of the deciduous molars. Usually, if the deciduous teeth are extracted 
 at the proper time, there will be little or no difficulty in their removal 
 as at this time the roots should be completely decalcified so that the 
 crowns are held in position only by the soft tissues. The instruments 
 
EXTRACTION OF ROOTS OF TEETH 607 
 
 for the extraction of deciduous teeth are practically the same as those 
 described in the extraction of the permanent teeth. In the handling 
 of these little patients no deception should be practiced. The patients 
 should be made acquainted with the fact that there will be some pain. 
 If they are deceived, subsequent operations will be performed with 
 much difficulty after the little patient has once lost confidence in the 
 operator. Frequently the roots of the deciduous teeth which have not 
 resorbed in the process of exfoliation of the deciduous teeth, will remain 
 in the jaws and will become wedged between the permanent teeth. 
 All such roots should be extracted when observed. Frequently the 
 employment of an elevator for this purpose will be more satisfactory 
 than the employment of forceps. 
 
 Extraction of Supernumerary Teeth. — ^When supernumerary teeth are 
 present, they are usually located in the region of the anterior teeth. 
 Occasionally they may be found distally to the third molar. When 
 these teeth are of no permanent value to the patient, they should be 
 removed. Frequently these teeth will prevent the eruption of the 
 permanent teeth, particularly in the region of the central incisors. 
 The early removal of them, therefore, should always be indicated. 
 The technic for extraction will not vary perceptibly from that for the 
 extraction of permanent teeth. 
 
 Extraction of Roots of Teeth. — One of the most common accidents in 
 the extraction of teeth is the fracture of a tooth, thus leaving certain 
 portions of the root in the alveolus. These fragments of the root should 
 always be removed because of the danger of future infection. They 
 may be removed by alveolar forceps or by elevators. The alveolar 
 forceps may sometimes be used very satisfactorily on roots in either 
 the superior or inferior maxilla. The forceps for superior roots are 
 those illustrated in Fig. 483. They consist of long narrow beaks and 
 sharp edges for the purpose of cutting through the alveolar process. 
 The technic for the extraction of these roots is to insert the beaks of 
 these forceps well up under the free margin of the gum mitil the 
 operator is sure that solid tooth structure will be encountered, and with 
 the sharp edges of the beaks to cut through the alveolar process, until 
 the forceps come into contact with the root to be extracted. Then by 
 the force of rotation and traction the root is removed from the socket. 
 This same technic should be used for the extraction of teeth that have 
 decayed under the free margin of the gmn. In the inferior maxilla 
 the technic is similar, using the lower alveolar forceps as illustrated in 
 Fig. 484. On account of the density of the alveolar process, elevators 
 may be used more advantageously than the forceps when one is operat- 
 ing distally to the cuspid teeth. The elevators for the removal of roots 
 which are very satisfactory are those illustrated in Fig. 486 known as the 
 
608 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 Cryer elevators. The method of procedure is to engage a portion of 
 the root with the point of the elevator, using the alveolar process as a 
 fulcrum and rotating the root out. In the multi-rooted teeth sometimes 
 the socket of one root may be used as point of access to the fractured 
 root. In roots which have been exostosed it may sometimes be 
 necessary to cut away the alveolar plate with a drill in order to remove 
 the root. This is best done by drills illustrated in Fig. 492, 
 
 Instruments. — ^The instruments used in the extraction of teeth are 
 forceps, elevators, chisels, drills, lancets, gum scissors, and mouth 
 gags and curettes. The proper selection of suitable instruments is a 
 matter of considerable importance and, since much depends upon the 
 instrmnents in this operation, a judicious selection of them should be 
 made. The mastery of the application of a few instruments is better 
 than a little knowledge of the application of many. The principal 
 instruments for the extraction of teeth are the forceps. The operator 
 should have a well selected set so that he may become thoroughly 
 familiar with every detail in their application. The principal features 
 of the forceps which should be taken into consideration in selecting 
 them are the beaks, joints, and handles. The beaks should be so 
 constructed that they will fit the tooth for which they are intended. 
 The ends of the beaks should be thin so that they may be inserted under 
 the free margin of the gum with ease. The beaks should be bent at an 
 angle with the handle so that the tooth may be grasped in line with its 
 long axis and permit of the extraction of the tooth without the inter- 
 ference of the handles of the forceps with the cheeks and lips of the 
 patient. To allow for an easy opening and closing of the beaks, the 
 joints of the forceps should have free play. The edges of the joints 
 should be rounded to avoid engaging the soft tissues in them while 
 operating. The handles should conform in so far as possible, to the 
 hand of the operator. By constant use of the forceps the operator soon 
 becomes accustomed to the feeling of them in his hands. All of the 
 forceps for the superior teeth should have full-ended handles (Figs. 479 
 to 485) to assist the operator in forcing the beaks of the forceps up under 
 the free margin of the gums. For the inferior teeth the handles should 
 be curved so as to fit the hand. One of the handles should be shorter 
 with a curved end to the handle which fits over the little finger when the 
 forceps are put into application. The following forceps have been 
 selected for the extraction of teeth because of the broad range of 
 usefulness. It is not possible nor practicable to give a complete descrip- 
 tion of all of the forceps that might be used in the extraction of teeth. 
 It is believed that if the operator will perfect his technic with a few well 
 selected forceps he will become more proficient. 
 
L._ 
 
 IarcI 
 
 Fig. 479 
 
 39 
 
 Fig. 480 
 
Fig. 481 
 
flARC 
 
 Fig. 482 
 
Fig. 483 
 
IXSTBVMEXTS 
 
 613 
 
 Forceps for Superior Trcfh. — For the superior teetli tlie following 
 forceps are essential: 
 
 Fig. 484 
 
 Fig. 4S5 
 
 Standard forceps Xo. 1, Fig. 479 for central lateral incisors, cuspids 
 and biscuspids. Both beaks are alike and set in line with the axis of 
 the handles. 
 
614 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 Standard forceps No. 3R and ;3L, right and left (Figs. 4S0 and 481), 
 for first and second molars. These forceps may be used also for the 
 third molars. The end of the buccal beak comes to a point so as to fit 
 between the mesial and distal buccal roots. The lingual beak is oval. 
 The beaks are set about two centimeters out of line with the axis of 
 the handle. 
 
 Standard forceps No. 4 for third molars (Fig. 482), which are appli- 
 cable to both sides of the arch. Both beaks are alike and set about 
 two centimeters out of line with the axis of the handles. 
 
 Standard forceps No. 2 and Standard forceps No. 5 (Fig. 483), for 
 roots of all of the upper teeth. Standard forceps No. 2 may also be 
 used for the extracting of the upper bicuspids. Both beaks are alike 
 and set about two centimeters out of line with the axis of the handles. 
 Standard forceps No. 5, has long and narrow beaks which are slightly 
 curved in their mesio-distal axis. 
 
 Forceps for the Inferior Teeth. — Standard forceps No. 6 for central 
 lateral incisors, cuspids, and bicuspids (Fig. 484) . These may also be 
 used as alveolar forceps in the extraction of all of the roots of the 
 inferior teeth. Both beaks are alike and set at an obtuse angle with 
 the handles. 
 
 Standard forceps No. 7 universal, for lower molars on both sides of 
 the jaws (Fig. 485) . Both beaks are alike and set at an obtuse angle 
 with the handles. 
 
 Elevators. — ^Elevators may be used to advantage in the removal of 
 lower third molars^ roots, and impacted teeth. Fig. 486 shows the 
 Cryer elevator. All elevators should have metal handles so that they 
 may be sterilized by boiling. This elevator is used in the extraction of 
 roots; the operator using the point to engage the side of the root and 
 with the alveolar process as a fulcrum rotates them out.- The Lecluse 
 or spade elevator (Fig. 487) , is useful in the extraction of the lower third 
 molar and for rotating out impacted teeth. The point and straight 
 side of the elevator are used to engage the side of the root or tooth 
 allowing the rounded surface to rotate on the alveolar process while 
 the tooth or root is being forced out of the socket. The shank of this 
 elevator may be straight or it may be canted at an angle to conform 
 with the position of the mouth in which it is used. Fig. 488 shows the 
 Jones elevator. It is designed somewhat after the Lecluse elevator. 
 It has a long narrow shank with a thin blade. This elevator is used in 
 the removal of lower third molars. The blade is inserted between the 
 second and third molars with the flat surface toward the third molar, 
 then by a rotary motion the third molar is loosened from its attach- 
 ments. This elevator may also be used in the dislodgement of roots 
 of teeth by placing the point of the elevator between the alveolar 
 
INSTRUMENTS 615 
 
 process and the tooth, engaging the tooth root with the point of the 
 elevator, and forcing the root from its socket. Fig. 489 shows the 
 
 Fig. 486 
 
 Heidbrink elevator. This is designed especially for roots in the ante- 
 rior part of the mouth when the decay has so far progressed that the 
 
616 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 use of a forcep cannot be satisfactorily employed. It is used by insert- 
 ing the blade in the interproximate space and forcing it between the 
 alveolar process and the root, or it may be used between the buccal 
 plate of the alveolar process and the root for the purpose of loosening 
 
 Fig. 487 
 
 Fig. 488 
 
INSTRUMENTS 
 
 617 
 
 the root. Fig. 490 shows the Crane elevator. This elevator has the 
 shape of an ice pick and can be used advantageously in the removal of 
 
 Fig. 489 
 
 Fig. 490 
 
 upper thu-d molars by forcing the point of the elevator through the 
 alveolar process, engaging the third molar v^ith its point, and with a 
 prying motion loosening the tooth from its attachment. 
 
618 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 Chisels. — Yig. 491 shows the Lyons chisel-elevators. These instru- 
 ments may be employed in the removal of impacted third molars. 
 These are the carpenter's edge chisels and are so designed that they 
 
INSTRUMENTS 
 
 619 
 
 may be used as ele^'ato^s as well as chisels. They may be used as 
 hand chisels or vnth the mallet. 
 
 Drills. — ^Fig. 492 shows the Henahan surgical bone drill. This may 
 be used for the piu-pose of cutting away the alveolar process around 
 tooth roots or cutting away the buccal plate around the alveolar 
 process siu-rounding impacted third molars. 
 
 Fig. 492 
 
 Lancets. — ^Fig. 493 shows a gum lancet. It should be of all-metal 
 construction so that it can be sterilized. The lancet is used to sever 
 the soft tissues around the teeth ^o as to prevent laceration of the 
 tissues in the process of extraction by the soft tissues adhering to the 
 tooth. Unless we have reason to believe that the soft tissues are 
 
 Fig. 493 
 
 adhering to the tooth, the lancet should rarely be employed previous 
 to the extraction, because hemorrhage from the incision of the lancet 
 might interfere with the operation. 
 
 Gum Scissors. — ^Fig. 494 shows curved scissors. This instrument 
 may be used advantageously in trimming gimi tissues around the 
 alveolar socket follo^^■ing extraction. It may also be used in severing 
 
620 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 the soft tissues from the tooth to prevent laceration. The scissors 
 may be used to advantage in trimming the soft tissues following the 
 operation of alveolectomy. 
 
 Fig. 494 
 
 Mouth Gags. — ^The mouth gag is a very valuable and indispensable 
 instrument for the dentist to have when extracting under a general 
 anesthetic. Fig. 495 shows a soft rubber mouth gag which is very 
 efficient for retaining the mouth open during the process of anesthesia. 
 When using a metal mouth gag, it is advisable to have a rubber protec- 
 tion over the jaws of it, so as to prevent injury to the tooth surfaces. 
 Fig. 496 shows a metal mouth gag which is very satisfactory when 
 operating around the mouth. The handles are away from the field of 
 
ACCIDENTS DURING THE PROCESS OF EXTRACTING TEETH 621 
 
 operation, and will not interfere with the mask or face-piece in the 
 administration of a general anesthetic. The gag should be applied 
 always on the side opposite the field of operation. 
 
 Fig. 495 
 
 Fig. 497 shows the Bogle curettes. These instruments may be used 
 following the extraction of abscessed teeth and the operation of apicoec- 
 tomy for mechanically eliminating infected areas. They may be used 
 also in any place where diseased tissue should be removed. The 
 handles are large and will permit of considerable pressure upon the 
 blades of the instruments. The blades are spoon shaped with sharp 
 cutting edges. 
 
 Accidents During the Process of Extracting Teeth. — Accidents will 
 happen frequently during the process of extracting teeth, and the 
 operator should be familiar with all of the features of such accidents 
 and should aim to prevent them whenever possible. There are many 
 accidents which are wholly unavoidable in the operation of extracting 
 teeth. There are many more which are avoidable but which frequently 
 happen to the beginner. When these accidents occur, the operator 
 should not become confused, but should remain composed so as not to 
 excite the patient. When it is necessary the patient should be made 
 acquainted with all the facts concerning the accident; this procedure 
 will instill assurance and confidence in the patient. One of the most 
 common accidents which occurs in the extraction of teeth is the 
 
622 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 fracture of a root. Such accidents may be avoided by making a careful 
 survey of not only the tooth, but the anatomic structures surrounding 
 the tooth before proceeding with the operation; then by the selection 
 of instruments adapted to the operation, many of these fractures may 
 be avoided. Much will depend upon the proper apphcation of the 
 
 Fig. 496 
 
 "forceps, and the movements which are required to loosen the tooth 
 from its attachments. Much will also depend upon the correct posi- 
 tion of the patient in the chair. In all cases of extraction, the operation 
 should not be done too rapidly because that is one of the causes of 
 many fractured roots. The patient may interfere with the proper 
 
ACCIDENTS DURING THE PROCESS OF EXTRACTING TEETH 623 
 
 Fig. 497 
 
624 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 application of forces by the operator, by grasping the operator's hands 
 or arms and this might predispose to fracture of the tooth. The roots 
 of the teeth may be abnormal in shape which fact may result in fracture 
 of the roots during the operation. Whenever a fracture of a tooth 
 occurs, the roots should always be removed. It is not permissible to 
 leave a portion of the tooth root in the socket, on account of the 
 probable chances of infection following later. 
 
 Fracture of the Alveolar Process. — A fracture of the external plate of 
 the alveolar process is not an infrequent accident following the extrac- 
 tion of upper molar teeth. This fracture may be so extensive that the 
 antral cavity will be opened. When such an accident occurs the 
 patient should be made aware of the fact, and the muco-periosteum 
 covering the walls of the antrum should be sutured back in normal 
 position. The posterior portion of the alveolar process and the 
 maxillary tuberosity may be fractured in the removal of an upper 
 third molar tooth. This may occur from two causes: first, if the beaks 
 of the forceps are improperly applied to the tooth so that the beaks 
 grasp the alveolar plate instead of the tooth, fracture may result when- 
 the forces of extraction are applied; second, in some individuals the 
 alveolar plate is so thin that when there is a calcification of the peri- 
 cemental membrane and adhesion of the membrane to the alveolar 
 process, the force required to remove the tooth may fracture the 
 tuberosity. These injuries should not be considered serious as com- 
 plete repair will take place almost as rapidly as if no fracture had been 
 made. Such a fracture can easily happen under a general anesthetic 
 when the operator may be operating with undue haste. 
 
 Another accident which may occur on account of a hasty operation 
 is that of extracting the wrong tooth. An accident of this kind is 
 wholly unwarranted. The operator should be very careful especially 
 when extracting under a general anesthetic, to see that the beaks of the 
 forceps are placed upon the proper tooth before using the forces of 
 extraction. Even when this has been done, the removal of a tooth 
 adjacent to the tooth to be extracted may occur. The roots of these 
 teeth may be partially fused together or the roots of one may be so 
 shaped that they will engage the other, thus making the extraction of 
 one without the other extremely difficult. When an adjacent tooth is 
 removed accidentally, it should be immediately replanted and ligated 
 to approximating teeth. Following this procedure, the pulp of the 
 tooth should be removed and the canal filled. The injury of unerupted 
 permanent teeth may occur when extracting deciduous teeth. This 
 may occur by the beaks of the forceps being inserted top deeply and 
 engaging the crown of the permanent tooth. In rare cases the roots 
 of the deciduous teeth may be attached or engaged to the crowns of 
 
FRACTURE OF THE ALVEOLAR PROCESS 625 
 
 the permanent teeth, such as the deciduous molar tooth root being 
 attached to the permanent bicuspid, and the removal of the molar 
 might loosen the bicuspid attachment to such an extent that both 
 teeth might be removed together. In the removal of a superior bicus- 
 pid or molar, there is a possibility of forcing a part or whole of the 
 tooth into the antral cavity by permitting the forceps to slip from the 
 tooth or root in the process of extracting, and forcing the tooth through 
 the thin wall of the antrum. It should always be removed even though 
 a radical antral operation be performed. It is never permissible to 
 leave such a foreign body in the maxillary sinus. This accident may 
 occur in forcing the root into an abscessed cavity which has been 
 formed in either upper or lower jaws. In these casss the ends of the 
 roots should always be accounted for, and the cavity should be suffi- 
 ciently opened to permit exploration of all its walls. In the removal of 
 an upper third molar, the operator may force it up into the spheno- 
 maxillary fossa where it may become lodged so that the position of it 
 can be ascertained only by the use of the roentgen ray. When such an 
 accident occurs, the patient should be apprised of the conditions, and 
 the tooth should be removed. In either the upper or lower jaws it is 
 always possible to force a tooth between the soft tissues and alveolar 
 process. In the lower jaw the tooth may be forced as deep as the 
 submaxillary fossa. In these cases, an explorer should be used to 
 locate the tooth, then by a properly shaped hemostatic forcep and 
 curved instruments, the tooth should be teased out. In those accidents 
 where the soft tissues are lacerated, it is good practice after sterilizing 
 the wound, to suture the mucous membrane as repair will take place 
 much more rapidly. 
 
 A quite common accident which occurs, is the loosening of an adja- 
 cent tooth or teeth. This is not serious, and by pressing back the tooth 
 into its position, rapid repair will take place. A crown or inlay may be 
 removed easily in the extraction of teeth. By close examination 
 previous to the operation, the operator may see the possibility of such 
 an accident, and he should acquaint the patient mth the possibility 
 so that if it occurs, the patient will not censure the operator. A porce- 
 lain crown may be fractured easily by the instruments being forcibly 
 brought in contact mth it during the operation. During the adminis- 
 tration of general anesthesia, when a mouth gag is used, the instriunent 
 should not come in contact vdth porcelain facings on account of the 
 possibility of fracture. Injury to the lips and adjacent tissues by 
 mouth gags should always be avoided. 
 
 The breaking of a point of an elevator or other instrument in the 
 process of extraction is an accident that occasionally occm-s, and when 
 it does, the point of the elevator or other instrument should be remo\'ed 
 40 
 
626 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 entirely. The wounding of the tongue, cheeks or floor of the mouth 
 is an accident that may occur during the extraction under a general 
 anesthetic. Such accidents occur for the reason that the mouth is 
 filled with blood and the field of operation is obscured so that the 
 forceps are improperly applied. When operating under a general 
 anesthetic the operator should always have a clear field before him. 
 This can be accomplished by the use of sponges. When such an 
 accident occurs sutures should be used to restore the parts to normal 
 condition. 
 
 Another accident that may occur is the dislocation of the mandible. 
 This may happen to those patients who are subject to habitual disloca- 
 tion of the jaws, or it may occur with any other patient where undue 
 force is exerted in the endeavor to remove a lower molar tooth. When 
 this occurs a reduction of the dislocation should be made immediately. 
 This can be accomplished by placing a block of wood between the 
 molars, and by pressing upward on the symphysis, and at the same time 
 causing considerable backward pressure, the head of the condyle thus 
 being forced back into the glenoid fossa. 
 
 Another accident that may sometimes occur in the removal of lower 
 third molars is a fracture of the mandible at the angle of the jaw. 
 This usually occurs on account of too much force being applied in the 
 attempt to dislodge the tooth. Such an accident may also occur by 
 cutting away so much of the mandible in an endeavor to release the 
 tooth that it becomes weakened. It will occur more frequently in 
 older than in the younger patients. When this accident occurs, the 
 mandible should be immobilized by interdental ligation. The lower 
 jaw should be immobilized for a period of four or five weeks. 
 
 Another accident that may occur particularly in the administration 
 of general anesthesia is that of a tooth slipping from the beaks of the 
 forceps in the process of the operation and passing into the pharynx. 
 This accident may be avoided by operating slowly and in those cases 
 where there is not good access to the field of operation, a sponge should 
 be placed back in the pharynx during the operation so that no foreign 
 body may drop into it. In the extraction of teeth under a general 
 anesthetic, when there is considerable hemorrhage, it is best to use an 
 aspirator for the purpose of keeping the blood out of the pharynx. 
 Pneumonia may be avoided by so doing. 
 
 Hemorrhage Following Extraction. — ^Hemorrhage following extraction 
 may be arterial, venous, or capillary in character, depending upon the 
 vessel from which the blood escapes. When arterial, it is usually 
 located in the socket of the tooth and may be stopped by packing 
 firmly the socket with medicated gauze or absorbent cotton. Before 
 inserting the cotton or gauze, it is good practice to roll the cotton in 
 
HEMORRHAGE FOLLOWING EXTRACTION 627 
 
 Monsel's solution or in tannic acid, or use it in connection with adrena- 
 lin chlorid for the purpose of contracting the arterial walls. Adrenalin 
 chlorid is a powerful vasomotor constrictor, and one of the most power- 
 ful hemostatics known. Although its effects do not last long after 
 the hemorrhage has once ceased, it is not difficult to keep it under 
 control. A pledget of cotton rolled to the shape of the tooth socket and 
 dipped in sterile sandarac varnish is very efficient in blocking off the 
 hemorrhage. A modeling compound impression of the socket may be 
 made and after it hardens it is withdrawn and coated with soft plaster 
 of paris and again inserted and held until the plaster of paris hardens. 
 This packing mil completely adapt itself to any part of the socket 
 and block ofi^ any vessel. It T\dll also remain in the socket with- 
 out retention of any kind. In those cases in which it is necessary 
 to cause pressure upon the wound in order to control the hemorrhage, 
 gauze or absorbent cotton should be placed between the jaws over the 
 wound, using a figm-e-of-eight or Barton's bandage to bind the jaws 
 together. 
 
 In the removal of several teeth there may be considerable hemor- 
 rhage follo\dng, particularly in anemic individuals, and it may test the 
 ingenuity of the operator to ascertain the best means of control. If 
 the hemorrhage is coming from more than one tooth socket, that fact 
 should be ascertained, and each socket treated separately until the 
 hemorrhage has subsided. In cases of hemorrhagic diathesis the 
 treatment should be begun before extracting. If the patient presents 
 with a history of bleeding, then he shoidd be placed under the care 
 of a physician for two or three weeks previous to the extraction of 
 the teeth. In such a case, the blood does not coagulate normally and 
 will be very slow in forming a clot. It is also possible in such a case 
 that the walls of the vessels have lost their tone so that the severed 
 vessels do not contract normally to close the lumen. ^Mien the 
 patient is in good health a hemorrhage will cease usually by a proper 
 coagulation and the normal contraction of the vessels. This abnormal 
 condition of hemorrhagic diathesis is brought about by certam diseases, 
 and an early examination should be made in these cases by a physician 
 before operating on many teeth. 
 
 "Whenever it is necessary to operate, the administration of calcium 
 lactate 10 to 15 grains, three or four times per day before the operation 
 will sometimes be of aid in the forming of prompt coagulation. When 
 the patient presents with such a history, it is not best to open too much 
 tissue at once; extraction of a single tooth at a time is always best. 
 
 If the hemorrhage is severe, it may be controlled by the injection 
 of horse serum in 10 c.c. doses. This promotes coagidation. Death 
 rarely follows as a result of hemorrhage after the extraction of a tooth. 
 
628 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 However, there may be marked constitutional symptoms as the result 
 of the loss of blood. In these cases the general appearance of the 
 patient is changed from the normal. The lips, ears, conjunctiva, as 
 well as the general integument are of a yellow color. The general 
 appearance of the patient is pinched or shriveled. The body is bathed 
 in a general sweat, the pupils dilated. Because the brain is anemic, 
 humming or roaring sounds are heard. The general sensibility is 
 benumbed, and if the loss of blood is severe, unconsciousness follows. 
 In these cases, the first thing to do is to control the hemorrhage, after 
 which stimulants are to be given the patient such as strong whisky 
 or brandy. When the patient has not been anesthetized, ether is a 
 good stimulant to ward off syncope. Atropia, j^q grain doses act as 
 a respiratory. External heat by hot water bottles should be used 
 diligently. Normal salt solution 100° to 105° F. as it emerges from the 
 needle should be injected into a vein or the soft tissue of the breast, 
 the abdomen, or the rectum. Injection into the breast or abdomen 
 requires no special apparatus but a large size hypodermic needle. A 
 great loss of blood may bring on a condition commonly known as shock. - 
 Pre-operative Treatment in the Extraction of Teeth. — ^Bacteria, as a 
 rule, gain entrance into the human system through rupture of the 
 tissues. A wound, an abrasion, and an inflamed or injured part pre- 
 pare the way for bacteria by lowering the local resistance. After this, 
 if followed by a profound constitutional depression, due to exposure, 
 excesses or disease, the growth of bacteria will be rapid and destructive. 
 The extraction of a tooth necessarily opens the tissues and prepares the 
 way for the entrance and propagation of microorganisms. In order 
 to limit the number of microorganisms which may enter the system 
 through a wound, prophylactic measures should be instituted previous 
 to the extraction of a tooth. These prophylactic measures should 
 consist of spraying out the mouth with a normal salt solution just 
 previous to the operation. This should be followed by painting the 
 field of operation with a 7 per cent, solution of tincture of iodin to 
 remove the gross sepsis. It should be understood that all instruments 
 connected with extraction of teeth should be sterilized on the same 
 plan as instruments are sterilized for any other surgical operation. 
 The instruments should be boiled for at least fifteen minutes previous 
 to using them. The aim should be to reduce the number of micro- 
 organisms that might possibly enter the system through the wound. 
 
 Post-operative Treatment. — ^Any accident that may have occurred 
 during the operation of extraction should be recognized at once by the 
 operator and treatment instituted as circumstances warrant. All 
 loose portions of the processes or loose pieces of the gum tissues should 
 be removed following the extraction. When there has been no patho- 
 
POST-OPERATIVE PAINS 629 
 
 logic condition present, when the gum tissue has not been contused 
 or lacerated, and when there have been no overhanging ragged edges 
 of the alveolar process, irrigating immediately with a 5 per cent, salt 
 solution will usually yield good results. This irrigation will flush out any 
 debris that may have entered and lodged in the tooth socket. The 
 primary hemorrhage which follows the extraction will usually cease in 
 a few minutes and a blood clot will be formed, which acts as a scaf- 
 folding, through which normal repair will take place. The blood clot 
 will protect the wound during the process of repair so that in these 
 simple cases further dressing will not be indicated. 
 
 The patient should be instructed to irrigate the mouth daily with a 
 5 per cent, salt solution. Simple cases of extraction wliich are treated 
 in this manner will usually cause no further trouble. In cases of 
 difficult extraction when there has been considerable traumatism to the 
 tissues, a condition of alveolitis may follow the operation. Immediately 
 following such an operation, the socket should be irrigated with a 5 per 
 cent, salt solution and counter-irritants such as aconite and iodin or 
 iodized phenol used to allay the inflammation. The patient should 
 return every day for treatment until the Inflammatory condition subsides. 
 In these cases, it is necessary to keep the field scrupulously clean. All 
 of the body eliminating processes should be made active. 
 
 When there has been a stripping off of the muco-periosteum to any 
 great extent over the alveolar process, it should be sutured back into 
 normal position, using horse hair or dermal suture for this pinpose. 
 In cases of extraction of teeth with alveolar abscess, the sockets should 
 be thoroughly curetted following the operation. Spoon shaped hand 
 curettes are the most desirable for this procedure. 
 
 In a case of extraction of a tooth with a granuloma at the apical end, 
 the same procedure should be instituted. In many cases it will be 
 necessary to remove the buccal plate over the sockets of the teeth in 
 curetting, so that every surface of the abscess cavity may be explored. 
 Following the curettage, the cavity should be irrigated and the treat- 
 ment instituted as for all other extractions. In case pus is present 
 following extraction of an abscessed tooth, packing the socket for 
 twenty-four hours with iodoform gauze for the purpose of maintaining 
 drainage is good procedure, after which the same treatment as in other 
 extractions will yield good results. All precautions should be used in 
 the extraction of teeth to prevent infection following the operation, 
 but if infection occurs, it should be treated in the same manner as an 
 infection that is present at the time of extraction. 
 
 Post-operative Pains. — The patients should be acquainted with the 
 fact that in all probability there will be some pain followhig the 
 operation of extracting a tooth. They should be informed that a 
 
630 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 wound in any part of the body as great as that made in the extraction 
 of a tooth will cause considerable pain, and the mouth will be no excep- 
 tion. Usually pain from simple extractions will not endure for any 
 great length of time. There are several conditions that will bring 
 about post-operative pain: 
 
 1. Extensive traumatism which results in alveolitis. 
 
 2. Infection either present at the time of the operation or following 
 the operation. 
 
 3. A fractured root with a portion of the pulp exposed that was not 
 removed. 
 
 4. Lack of normal blood supply to the parts, which results in the 
 formation of the so-called dry socket. 
 
 In the first and second instances, the treatment should be instituted 
 as indicated above for alveolitis. In the third instance all particles 
 of the tooth root should be removed even though greater traumatism is 
 produced. In the fourth instance where there is a dry socket formed, 
 a curettage of the tooth socket is indicated and an effort made to pro- 
 mote a flow of blood so that a clot may be formed in the tooth socket, 
 and the normal process of repair permitted to proceed. In all cases 
 of untoward sequelae following the operation of extraction of teeth, 
 the patient should be kept under observation by the operator until 
 normal conditions have become reestablished. 
 
 Remedies for post-operative pain following extraction are given 
 under "Post-Operative Treatment for Impacted and Unerupted 
 Teeth." 
 
 IMPACTED AND UNERUPTED TEETH. 
 
 The Impacted Lower Third Molar. — ^This condition is in a large per- 
 centage of cases caused either by lack of normal development, or by 
 arrested development of the inferior maxilla. The second rnolar 
 immediately in front and the coronoid process behind bound the space 
 allotted to the third molar. Each tooth which has no deciduous 
 predecessor is developed beneath the base of the coronoid process. 
 This is true of the first, second, and third permanent molars. The 
 only manner in which these teeth are able to take their places in the 
 normal arrangement of the teeth in the jaw is by the physiologic 
 resorption of the anterior surface of the coronoid process. While this 
 process of resorption is going on, on the anterior surface of the coronoid 
 process, through the laws of compensation, nature has provided for a 
 deposition of bone on the posterior surface of the condyloid process. 
 Through these two physiologic processes, resorption and deposition of 
 bone respectively, all of the molars are able to erupt into their proper 
 
IMPACTED AND UNERUPTKI) TEF/ril 
 
 031 
 
 positions. Figs. 498, 499 and 500 show (le\cloi)ineiitHl stages of first, 
 second, and third molars. 
 
 Fig. 498 
 
 Fig. 499 
 
632 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 However, when either or both of these physiologic phenomena in the 
 process of development of the mandible are arrested, the interval 
 between the anterior surface of the coronoid process and the last 
 erupted tooth which is usually the second molar, will be insufficient for 
 the normal arrangement of the presenting third molar. Under these 
 conditions, the tooth in pressing forward, takes a direction in which 
 the least resistance to its progress is offered and a condition becomes 
 manifest which is termed impaction. 
 
 Fig. 500 
 
 Another condition which must be recognized in accounting for the 
 mal-position caused by the impaction, is that the tooth has been directed 
 from its course at a comparatively early period of development, irrespec- 
 tive of resistance offered at the time of eruption. This condition may 
 be accounted for by a change in the character of the cancellous bone 
 immediately adjacent to the developing tooth. If, through some 
 inflammatory process, peculiar to the individual, or by the same process 
 set up through some pathologic disturbance, or trauma, a secondary 
 deposit of dense bone is laid dowU; around the developing tooth, a 
 
IMPACTED AND UNERUPTED TEETlf O-W 
 
 change in the (hrection of ernption of the tooth may take ])lace or tliere 
 may be a prevention of its eruption. This retarded condition is also 
 due to the fact that at the points where all of the other teeth are 
 located, soft spongy bone or alveolar process is found and resor])ti()n 
 of tissue takes place more readily at these points than at the points of 
 eruption of the third molars which is made up of dense cortical or true 
 bone. Frequently the third molar will erupt u?itil it comes in contact 
 with the second and then stop on account of insufficient space, in which 
 case only a small part of the tooth will be presented. An upper third 
 molar presents an entirely different condition on account of the dif- 
 ference in the character of the bones in the superior and inferior maxillae. 
 When, for any reason there is a retarded development of the superior 
 maxilla which makes it shorter in its anterior posterior diameter, so 
 that there is not sufficient room for the normal eruption of the third 
 molar, the crown of this tooth will point toward the cheek, taking the 
 direction of least resistance in its course. It slides out to the side, being 
 guided by the second molar, which is already in place. If there were 
 sufficient room, both upper and lower third molars would erupt without 
 pain, but this is rarely the case. 
 
 The cuspids are the next in the series most likely to be impacted. 
 The etiology of this condition is the same as that of the impacted molars, 
 namely, insufficient spaces for the normal presentation of the teeth 
 in the process of eruption. The cuspid teeth make their appearance 
 long after the eruption of the lateral incisors and sometime after the 
 eruption of the first bicuspids. In case of retarded development of 
 the maxillse, there may not be sufficient room between the lateral 
 incisors and first bicuspids for normal eruption of the cuspids and as a 
 result impaction occurs. 
 
 On account of the tendency of erupting teeth to follow the course of 
 least resistance, they will slide out to the buccal or into the lingual 
 surfaces of the maxillse. It is also true that at an early period of 
 development of these teeth, a secondary deposit of bone in the maxillse, 
 due to an inflammatory process, may influence a change of direction 
 in the developing teeth so as to change their position entuely when they 
 erupt. 
 
 While the thu-d molars and cuspids are predisposed to impaction 
 more frequently than any others, yet any tooth in either maxilla may 
 become impacted if the environment is not such that normal eruption 
 can be made possible. 
 
 The next anomaly which may be considered is the unerupted or 
 aberrant tooth. This condition may be present in any part of either 
 maxilla and any tooth may be the offending member. 
 
 There is alwa}^s a reason for such teeth being unable to erupt norm- 
 
634 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 ally. The developing teeth meet some obstruction in their normal 
 course, such as supernumerary teeth or normal teeth which have 
 previously erupted and already occupy the space belonging to the 
 erupting teeth. Again, a previous inflammatory condition in the 
 cancellous bone may have set up secondary deposits of dense bone 
 which will prove an obstruction to the developing teeth and deflect 
 them out of normal alignment. 
 
 Pathologic Possibihties. — Some of the pathologic conditions which 
 are induced by these dental anomalies will now be considered. The 
 impacted lower third molars will be taken up first. 
 
 Perhaps the most common disturbance to be encountered is local 
 infection of the soft tissues surrounding the teeth. This condition is 
 usually present in the partially erupted teeth when the gum tissue 
 which should occupy the space between the anterior surface of the 
 coronoid process and third molar has been forced out over the disto- 
 occlusal surface of the tooth and becomes contused in mastication. 
 Bacteria-laden saliva and food particles are forced into the interstice 
 between the tooth, and swollen tissue and infection take place. Inflam- . 
 mation is set up and maintained, which is not limited to the injured 
 parts, but more commonly extends to the adjacent structures involving 
 the soft textures about the ascending ramus and frequently involving 
 the paratonsilar region. 
 
 Deglutition becomes painful and trismus is set up. Many times the 
 patient is imable to open the jaws more than two or three millimeters. 
 After a time suppuration takes place and the movements of the jaws 
 become less constrained. 
 
 In these acute conditions immediate surgical procedure is contra- 
 indicated. The treatment indicated is to apply counter-irritants, the 
 application of cold compresses or ice to the face, and to have all of the 
 body eliminating processes active. 
 
 After the inflammation has subsided and the jaws have become less 
 constrained, conditions should be restored to normal by surgical pro- 
 cedure to obviate repeated attacks. This condition will rarely be found 
 around other impacted teeth than the lower third molars. 
 
 A pathologic condition which may occur as a result of an impacted 
 tooth is pressure resorption. When the crown of one of these teeth is 
 lodged or impacted against the root of an adjacent tooth, the hard 
 enamel surface of the impacted tooth will cause a resorption of the 
 tissues of lesser resistance of the other one. This may go on to such an 
 extent that the pulp of the adjacent tooth will be encroached upon. 
 
 A very serious condition may arise from an impacted lower third 
 molar by pressure being exerted upon the inferior dental nerve. The 
 position of this tooth in the maxilla predisposes to impingement upon 
 
IMPACTED AND UNERUPTEl) TEKTII 035 
 
 the inferior dental canal. In such cases a reflected ])aiii may be set 
 up which will be expressed in any part of the liead wliicli lias its 
 sensory nerve supply from the fifth or trigiminal nerve. 
 
 Neuralgia may have its etiology in such conditions. The late 
 Dr. Henry S. Upson, former professor of Neurology in the Western 
 Reserve University, ascribed many of the nervous disorders which 
 "mankind is heir to" to impacted teeth. He stated that "certain 
 types of nervous disturbances caused by dental impactions have almost 
 the clearness of a laboratory experiment, as in them the severest 
 symptoms are set up by the simplest irritant. Pain may be from the 
 beginning to the end quite lacking." It is the constant though mild 
 irritation, perhaps not sufficient to produce pain, that sets up some of 
 these nervous disturbances which may of themselves take on a \'iolent 
 form. 
 
 Alopecia areata, or baldness occurring in sharply defined patches, 
 leaving the scalp smooth and white, is a condition due to a nervous 
 disturbance. An impacted tooth must be considered an etiological 
 factor in this affection. 
 
 During the last few years, the author has had several cases of this 
 nature that showed marked improvement after the removal of impacted 
 teeth. 
 
 Another abnormal condition that is quite frequently found associated 
 with the presence of impacted lower third molars is a tendency for 
 these teeth in their effort to erupt to force all of the lower teeth forward. 
 Orthodontists have found it almost impossible to retain normal occlu- 
 sion following orthodontic treatment with these teeth present in the 
 jaws. Many fine orthodontic results have been ruined by the presence 
 and activity of impacted teeth. 
 
 What are the pathologic possibilities of unerupted teeth? It is a 
 remarkable fact, and one which has not been fully explained, that 
 unerupted teeth having lain dormant for years in the jaws suddenly 
 become the seat of purulent inflammation wdth sometimes serious 
 symptoms. Such cases are by no means rare. Some lATiters are of the 
 opinion that under certain conditions such teeth may act as foreign 
 bodies and may even fall prey to resorption. Under these conditions 
 where an irritation has been set up and piuulent inflammation has 
 become seated, a bone abscess may form around the region of an 
 unerupted tooth. This abscess may develop until a large portion of the 
 maxilla becomes involved. 
 
 Another condition which is seen frequently in the mouths of men 
 and women under thirty years, is the cystic growths connected with 
 these teeth whose eruption is retarded. In the light of our present 
 knowledge the explanation for the formation of these cysts is largely 
 
636 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 theoretical. Tomes has suggested the most plausible theory. He 
 states that when the development of the enamel of a tooth is com- 
 pleted, its outer surface becomes perfectly detached from the investing 
 soft tissue and a small quantity of transparent fluid not uncommonly 
 collects in the interval so formed. This fluid ordinarily is discharged 
 when the tooth is erupted, but when from some cause the eruption of 
 the tooth is prevented, it increases in quantity and gradually distends 
 the surrounding tissues, causing a resorption and disintegration of the 
 osseous structures. These cysts may go on developing until a large 
 portion of the maxilla is involved. 
 
 Again, an unerupted tooth may, by coming in contact with the roots 
 of the normal erupted teeth, cause pressure resorption and thus produce 
 a permanent injury to them. When this tooth lies in close proximity 
 to a nerve trunk, it may cause undue pressure and set up the same 
 obscure nervous disturbances which have been attributed to impacted 
 teeth. 
 
 Treatment.^ — ^We have considered briefly the etiology and pathology 
 of some of these dental anomalies. We will now consider the treatment. 
 
 An unerupted tooth should be removed when it is suspected of any 
 disturbance. Successful diagnosis is made only by a process of 
 elimination and when such a tooth is present in the jaws and the patient 
 is suffering from obscure nervous disturbance, the removal of it is 
 indicated in order to eliminate a possible source of trouble. Its 
 removal, together with the entire cystic lining must be accomplished 
 in cases of dental cysts. This should not be attempted without a 
 good roentgenogram, which should point out the location of the tooth 
 and the dimensions of the cyst. 
 
 In fact, the removal of any unerupted tooth should not be attempted 
 without a good roentgenogram for the reason that any unnecessary 
 cutting or laceration of the tissues is not permissible in these operations. 
 In the removal of these teeth the author prefers to uncover them by 
 means of a chisel and mallet, thus the landmarks are not destroyed 
 which otherwise might be the case in the use of the bur and engine. 
 After the location of the tooth and the character of its environment 
 have been determined, the use of the bur or drill is permissible in the 
 further removal of the osseous tissues and in the dislodgment of the 
 tooth. 
 
 In the removal of an impacted tooth other than the lower third 
 molar, no definite technic can be followed since each case will usually 
 present entirely different conditions. 
 
 In the removal of the impacted lower third molar, however, the 
 author believes that it is possible to follow a definite technic in prac- 
 tically every case. In other words, the operator should have a clear 
 
IMPACTED AND UN ERUPT ED TEETH 637 
 
 conception of the whole situation and know exactly what has to be 
 accomplished in order to remove the tooth with the least amount of 
 traumatism. In a large percentage of cases no more traumatic injuries 
 should be made upon the osseous tissue than in the extraction of the 
 first or second molars. 
 
 The difference in the character of the process of repair of the two 
 wounds is due largely to the extent of the pre-operative inflammatory 
 process present, which is usually very much greater in the case of an 
 impacted molar. 
 
 Technic for Removal of Impacted Lower Third Molars. — After the field 
 of operation has been sterilized of its gross sepsis and anesthetized, an 
 incision 1 centimeter long is made through the soft tissues over the 
 tooth. Then a vertical incision is made about 2 millimeters distal 
 to the second molar and extended to a point half way between the 
 gingival margin and the root of the second molar (Fig. 501). The 
 triangular flap is then raised, exposing the osseous tissue surrounding 
 the tooth (Fig. 502). 
 
 The next step is to remove by the chisel and mallet a section of the 
 process overljdng the tooth to an extent that there will be sufficient 
 space between the second molar and the osseous structure covering 
 the tooth to permit it to be displaced (Fig. 503). A surgical drill is 
 then used to remove a section of the cortical bone 2 mm. in mdth 
 contiguous to the buccal surface of the tooth (Fig. 504). The wedge 
 of cancellous bone between this surface and the tooth socket is readily 
 removed with the chisel. Then the chisel is driven between the 
 buccal surface of the tooth and buccal plate of the alveolar process 
 mth the bevel of the chisel next to the buccal plate, and by a prying 
 motion the buccal and lingual plates are sprung apart sufficiently to 
 loosen the tooth (Fig. 505) . Fig. 506 is a cross-section of an impacted 
 third molar, showing the thin lingual plate. Then, by means of an 
 elevator (preferably the Lecluse) the tooth is rotated backward and 
 out (Figs. 507 and 508). At the stage in the operation necessitating 
 the use of the elevator, the chisel may be used as an elevator and the 
 tooth removed. The elevator should never be used until the tooth is 
 seen to rotate slightly in its socket under the stress of the chisel. Until 
 this time, the impaction has not been relieved, and any attempt to 
 use the elevator might result in fracture of the tooth or of the alveolar 
 process, or even of the mandible. 
 
 The same principle is followed with any degree of impaction and 
 also with a tooth that is not only impacted but unerupted as well. 
 The cutting should all be done from the buccal siu"face, as there are no 
 vulnerable tissues at this point, while on the lingual siuface the lingual 
 nerve and artery might be injm"ed if much cutting were attempted. 
 
638 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 Under novocain anesthesia there is very little hemorrhage and this is 
 controlled by a gauze sponge inserted on the buccal surface adjacent 
 
 Fig. 501 
 
 Fig, 502 
 
 to the operative field. There is one point for the operator to keep in 
 mind and that is that the impacted tooth is wedged into the jaw and 
 the impaction has to be relieved before the tooth can be removed. 
 
IMPACTED AND UNERUPTED TEETH 
 
 639 
 
 This may be done with burs, drills, stones, cutting forceps or chisels. 
 The wound made from the chisel is a clean sharp one and not rough 
 
 Fig. 503 
 
 Fig. 504 
 
 and ragged such as those made by burs. Conseciuently repair will 
 take place around a wound made with a chisel much more quickly 
 than if the tissues are lacerated by burs. 
 
640 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 Post-operative Treatment. — ^The procedure which has been very 
 satisfactory in the author's hands is to saturate plain or iodoform 
 gauze with euroform paste and pack the socket with it for twenty-four 
 hours immediately after the operation. This preparation is antiseptic 
 
 Fig. 505 
 
 and its sedative action is most beneficial. At the end of twenty-four 
 hours the dressing is removed and the patient instructed to use a warm 
 5 per cent, salt solution as a mouth wash. Dentalone on absorbent 
 cotton rolls inserted into the socket may be used to advantage. 
 
 F 
 
 ^ 
 
 
 1 
 
 / 
 
 
 U 
 
 ^^S 
 
 *l 
 
 H 
 
 
 ¥ 
 
 b. '. ,^ 
 
 
 ^ 
 
 Fig. 506 
 
 The wound should be kept free from all food deposits and debris 
 by the use of sprays of 5 per cent, salt solution, until repair takes place. 
 No curettage is necessary in these cases unless an abscessed condition 
 
IMPACTED AND UNERUPTED TEETH 
 
 641 
 
 is present, in which case curettage of the socket is indicated. In cases 
 of post-operative pain, asperin 15 grains may be given as a nerve 
 sedative. Pyramidon in 5-grain doses acts as an antip\Tetic and an 
 
 Fig. 507 
 
 Fig. 508 
 
 analgesic and will yield good results. Dusting of anesthetic powder 
 such as novocain powder, novoesthene or parathesen into the socket 
 will be an aid incontrolling post-operative pain. 
 
 41 . 
 
642 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 A thorough knowledge of the pathologic possibilities of these dental 
 anomalies, a definite technic for their elimination, and a scientific 
 treatment for pre-operative and post-operative conditions are all 
 essential for success. The personal ability of the operator will be the 
 predominating factor in the success or failure in their diagnosis and 
 treatment. 
 
 Fig. 509 
 
 External Alveolectomy.^ — In cases of prognathism it is sometimes 
 very desirable to remove the external alveolar plate in either the upper 
 or lower jaws, or both, following the operation for the extraction of 
 teeth. By so doing, a more efficient denture can be obtained. This 
 operation can be done either under local or general anesthesia, and 
 should be done immediately following the operation for the extraction 
 of teeth when indicated. Fig. 509 shows a case in which such an 
 
 1 The author is indebted to Dr. Wm. L. Shearer, of Omaha, Nebraska, for the valuable 
 illustrations in the external alveolectomy and the modified external alveolectomy. 
 
IMPACTED AND UNERUPTED TEETH 
 
 643 
 
 operation is indicated. After the extraction of the teeth the muco- 
 periosteum is reflected back by means of a flat periosteal ele\'ator 
 to a point opposite the apices of the tooth sockets. This is shown in 
 Fig. 510. Then by Rongeur forceps (Fig. 511) the external plate of the 
 alveolar process is entirely removed. At the same time the border of 
 the internal plate is made straight and smooth (Fig. 512). Following 
 this, the internal and external margins of the periosteal flaps are 
 trimmed so that even margins are obtained. The flaps are then 
 brought together and sutured, bringing the outer and inner muco- 
 periosteal flaps into normal position over the exposed bone, as illus- 
 trated in Fig. 513. The sutures should be left in for a period of 
 
 Fig. 510 
 
 about eight days. This operation can be used advantageously in any 
 case following extraction of all the teeth. The operator can so shape 
 the ridge of the mouth as to make an artificial denture more efficient. 
 Modified External Alveolectomy.— INIodification of the operation of 
 external alveolectomy may be made successfully in cases where exten- 
 sive curettage is indicated. Fig. 51-1 illustrates a case where the buccal 
 plate of the alveolar process is involved through to the muco-perios- 
 teum. Such a case usually represents an infectious process of long 
 standing, or what is termed chronic dento-alveolar abscess. In some 
 of these cases by raising the muco-periosteal flap, as illustrated, the 
 granuloma will be raised with the flap and it is sometimes ^•ery adherent 
 

 J 
 
 V. 
 
 Fig. 511 
 
IMPACTED AND UNERUPTEf) TEF/rif 
 
 645 
 
 «l»s^^ 
 
 il 
 
 w/ 
 
 l^^ 
 
 WW 
 
 aT^ 
 
 
 1 
 
 FiG.'512 
 
 Fig. 513 
 
 Fig. 514 
 
 Fig. 515 
 
646 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 by a tough fibrous tissue attachment. After raismg the muco-periosteal 
 flap, all diseased areas should be curetted thoroughly as shown in Fig. 
 
 515. This procedure is of advantage to the operator since he can see 
 when he has curetted down to healthy tissue. The muco-periosteal 
 flap is then returned to normal position and sutured as shoT\Ti in Fig. 
 
 516. These sutures should be removed after six or eight days. 
 
 
 
 , ^ 
 
 
 
 J^ 
 
 Ipip^^ /- 
 
 -^_ 
 
 
 ¥i 
 
 ^^k 
 
 1 
 
 I 
 
 
 
 Clte^ 
 
 1 
 
 \ 
 
 
 Im 
 
 ^^c>^ 
 
 
 
 iH^rC'' 
 
 ^p^ 
 
 
 
 1 nS&^fitf 
 
 / 
 
 
 
 Mm: 
 
 1 
 
 1 
 
 
 ^/f' 
 
 4' 
 
 ■ \ - 
 
 1 
 
 
 Fig. 516 
 
 The post-operative treatment for both the external alveolectomy, 
 and the modified external alveolectomy consists of keeping the sm"faces 
 absolutely clean with sprays of 5 per cent, salt solution and painting 
 the surfaces with 20 per cent, solution of argyrol. 
 
 Apicoectomy. — The author has previously referred to apicoectomy as 
 a means of eradicating infection aromid certain teeth. It has seemed 
 advisable to treat this subject followdng that of extraction of teeth. 
 
 Indication and Contra-indication for Apicoectomy. — ^For many years 
 ends of roots of teeth have been excised under the names of root 
 amputation, root excision, maxillotomy, apiectomy, apicoectomy, 
 and root resection. As early as 1884 the technic of the operation was 
 
IMPACTED AND UNERUPTED TEETH 647 
 
 described by Farrar. Many writers since that time have written on 
 one phase or another of the subject until today it would seem that 
 this is an operation that should become an important one in every well 
 conducted dental practice. 
 
 Dental and medical science have made it clear that pathologic 
 conditions of the pericemental membrane and diseased ends of the 
 roots of the teeth are a contributing factor to, and frequently the 
 primary cause of, general systemic distiu-bances. Dentistry must 
 now assume the tremendous responsibility of eliminating these morbid 
 conditions, either by the extraction of the teeth followed by a curettage 
 or by some other surgical or therapeutic procedure. 
 
 It is a well known fact that with the present methods of root canal 
 therapy few of these morbid conditions can be eliminated. Assimiing 
 then that our deductions are correct, there is only one course left open, 
 namely, surgical procedure. 
 
 The surgical procedure can be accomplished in one of two ways — 
 either by the extraction of the tooth and ciu*ettage, or by opening 
 through the alveolar process, excising the diseased root end, and 
 thoroughly curetting the diseased area. 
 
 The question now arises, how are we to make a correct diagnosis of 
 the case so as to govern our surgical procedure? 
 
 No hard and fast lines can be drawn as to just where apicoectomy is 
 indicated and w^here extraction of the tooth should be the operation 
 of choice. 
 
 Apicoectomy is by no means a "cure all" for all conditions of 
 chronic alveolar abscess when medicinal therapy has failed. Indeed 
 it is the opinion of the author that in many of these cases the patient's 
 welfare will be better taken care of if extraction of the tooth followed 
 by curettage is resorted to. 
 
 What then are to be the signs and symptoms which mil govern in 
 the selection of the operation that is indicated? 
 
 A correct diagnosis of each case is not at all a simple matter. The 
 first thing to take into consideration is the present state of health, 
 past illness, and the possible recuperative or reserve force of the 
 patient. The lowering of the vitality through chronic alcoholism or 
 such diseases as tuberculosis, s^q^hilis, and diabetes which lead to a 
 state of constitutional dyscrasia will have a profound influence in 
 preventing repair after these operations. In such cases the operation 
 of choice in eliminating the pathologic conditions around root ends is 
 extraction of the offending tooth followed by thorough curettage of 
 the bone. Age may be a factor which should be considered in deter- 
 mining the indications and contra-indications for apicoectomy. In the 
 aged the process of repair is slow and the prognosis for bone repair is 
 
648 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 not so good as in the young or in the middle-aged. In a patient of 
 advanced years it would be a question whether the cavity following 
 this operation would be filled in with normal tissue. Particularly would 
 this be true if there were much involvement of the apical area, conse- 
 quently the operation would be undertaken with considerable hazard. 
 
 The normal or abnormal circulation of the blood is another factor 
 that plays a very important role in the success or failure of the opera- 
 tion. It is an established surgical fact that without a certain definite 
 blood supply to a part, repair of tissue will not take place. Notwith- 
 standing the fact that the teeth and surrounding tissues have a very 
 rich blood supply, in certain types of individuals and under certain 
 pathologic disturbances such as in the anemic and poorly nourished, 
 there is not sufficient blood supply to the apical area to insure repair 
 of the parts after the operation. This condition is found in the young 
 as well as in the aged, and the clever diagnostician will discover it 
 before making his decision as to whether apicoectomy or extraction 
 is indicated. 
 
 It is unfortunate that many men are depending entirely upon the 
 roentgenogram in diagnosing mouth infection and are governing their 
 whole course of treatment on this knowledge alone. They seem to 
 overlook the fact that the roentgenogram is merely the shadow of 
 conditions in the bone and does not show a picture of the pathology 
 involving the parts. 
 
 In making the diagnosis which will lead to an operation such as 
 apicoectomy, the roentgenogram must be used as only one of our 
 means of forming our conclusions. The roentgenogram may show the 
 appearance of greater pathology than is actually present and again 
 the tooth root may be interposed between the ray and the morbid 
 area in such a way that it may appear that little or no pathology is 
 present; therefore the extent of the pathologic involvement that will 
 appear to be present will depend upon the angle from which the roent- 
 genogram is taken. This you will readily conceive is not sufficiently 
 definite to rely upon wholly in forming a judicious and conservative 
 diagnosis. The roentgenogram then should be considered only one 
 link in the chain of evidence upon which we must base our decision. 
 Then again, there may have been some involvement and rarefaction 
 of the tissues before therapeutic measures were resorted to, which the 
 patient's natural power of immunity and resistance will clear up after 
 the infection has been eliminated from the canal and tubuli of the 
 tooth. 
 
 If we can be satisfied that the end of the root is not denuded of its 
 pericemental membrane, then, in the author's opinion, the case may be 
 watched and a series of roentgenograms taken at stated intervals and 
 
IMPACTED AND UNERUPTED TEETH 649 
 
 compared. The patient should be apprised of the fact that this par- 
 ticular tooth is under suspicion. Here again the general state of health 
 of the patient must be considered, and the technic of sterilizing and 
 filling the root canal must be a part of the chain of evidence which 
 governs our procedure. 
 
 If the case be an alveolar abscess of long standing or an imperfectly 
 filled root canal with granuloma where all the evidence points to dis- 
 ease and death of the pericemental membrane in the apical area, it is 
 the opinion of the author that surgical procedure rather than dental 
 therapy is indicated. 
 
 The character of the surgical procedure may be apicoectomy in 
 favorable teeth and extraction of the teeth in unfavorable cases. 
 What are to be considered favorable cases for apicoectomy? 
 
 The operation is often done with the view of saving a nice piece of 
 bridge work and no attempt is made to eliminate the source of the 
 infection. It should be a matter of routine that the canals and tubuli 
 be sterilized and filled just previous to the operation. We are not doing 
 good surgery when this is not done. 
 
 The most favorable teeth for this operation are single rooted teeth. 
 This limitation has been made for two reasons. First, because of the 
 accessibility of these teeth, a clean surgical operation can be performed. 
 Second, sterilization and filling of the root canals can be made more 
 accurate. 
 
 In multi-rooted teeth the patient's welfare will be better taken care 
 of by extraction of the tooth followed by curettage of the bone. In no 
 case should this operation be resorted to when the tissues are diseased 
 beyond the apical third of the root of the tooth. 
 
 The success of the operation will depend upon whether or not the 
 diagnosis has been correct. The welfare of the patient should be the 
 first consideration and a hasty diagnosis may lead to an operation 
 rather than a successful treatment of the condition. 
 
 Surgical Technic of Apicoectomy. — ^The foundation upon which the 
 success or failure of this operation rests, is the condition of the root 
 canals and tubuli, and the extent of pathologic involvement. It is 
 imperative that the canals and tubuli be sterilized and the canals filled 
 just preceding the operation. The possibilities^ of reduced silver in the 
 preparation of roots for resections, seem most encouraging. 
 
 The silver solution used for rapid reduction is made up as follows: 
 silver oxid is precipitated from a silver nitrate solution with KOH or 
 NaOH. This is carefully washed to remove all impm-ities and kept 
 moist in a small amber-colored bottle. In this condition reduction is 
 
 1 This is a modification of a method advocated by Howe for silver reduction. 
 
650 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 so slight that it can be kept for a long time without much change. 
 If a small amount is insoluble in excess of ammonia, there has been too 
 much reduction and the silver oxid should be freshly prepared. This 
 is the stock solution and it will be seen that it is more desirable than 
 the ammoniacal solution made from silver nitrate, because it is free 
 from nitric acid and other impurities. 
 
 When rapid reduction is desired as for apicoectomy, the silver oxid 
 is added to a drop or two of ammonium hydroxid to the point of 
 saturation. This forms silver ammonium oxid. In this state the 
 ammoniacal solution is reduced easily. The case in which reduction 
 takes place with this solution is so marked that bm-nishing with a 
 warm glass rod is sufficient to reduce it to the lustrous metallic silver. 
 A precaution that should be mentioned is that after a few hours, ful- 
 minates of silver may be formed from the ammoniacal solutions, which 
 are very explosive. Serious accidents are possible from even wet 
 solutions. Only very small amounts of ammoniacal solutions should 
 be made and the unused portion discarded immediately after treat- 
 ment. After complete reduction there is no danger and only old ammo- 
 niacal solutions, especially after drying, are to be avoided. 
 
 The following technic is the one used preparatory to resection: the 
 canals are opened, using the rubber dam, and the silver solution is 
 introduced to the very apex. Five or ten minutes are allowed for 
 penetration before the reducing agent is applied. This treatment is 
 applied several times. The canals are then very carefully filled by 
 packing with small pieces of gutta-percha points softened by gently 
 heating or other acceptable material. 
 
 Assuming now that the root canals and dental tubuli have been 
 sterilized and the root canals properly filled, what is the modus operandi 
 of apicoectomy? 
 
 In the first place, this operation consists of invading the soft tissues 
 as well as the alveolar process, and a recognition of the difference 
 between surgical and dental cleanliness must be made. If this opera- 
 tion is • to take a place in conservative practice, the same surgical 
 asepsis must be maintained not only in the field of operation, but with 
 the operator as well, as would be necessary in any surgical work in the 
 same or a similar field. 
 
 Local anesthesia, either conduction or infiltration, is the anesthetic of 
 choice for this operation on account of the ability to secure the coopera- 
 tion of the patient and to control the hemorrhage. These are factors 
 not to be ignored. Clinical experience has demonstrated that an 
 isotonic anesthetic solution if properly used does not interfere with the 
 process of repair. 
 
 After the field has been anesthetized, the first step in the operation 
 
IMPACTED AND UNERUPTED TEETH 651 
 
 is to remove the gross sepsis from the field of operation. Tliis is 
 accompHshed by the use of alcohol to dry the surface over the field of 
 operation, followed by swabbing with 7 per cent, tincture of iodin. 
 
 A curved incision is then made over the point where the tooth is to 
 be resected, about 2 centimeters in length with the convexity toward 
 the cervical line. The incision should be made through the muco- 
 periosteum to the alveolar plate. The muco-periosteum is then raised 
 by blunt periosteal elevators to form a muco-periosteal flap. By so 
 doing, the outer plate of the alveolar process over the infected area is 
 exposed. In some cases the outer plate will have become disintegrated 
 so that the raising of the periosteal flap will expose the apical end of the 
 tooth root. In other cases, when the outer plate of the alveolar 
 process is intact, the apical end of the tooth root may be exposed by 
 the use of sharp hand chisels, using them to cut away the outer plate 
 until the root end is exposed. The author prefers the chisels for expos- 
 ing the root end on account of the ability to preserve the landmarks 
 during the entire operation. 
 
 A sufficient area of the outer plate should be removed so that the 
 infected crypt and the apical end of the tooth root are exposed. The 
 resection of the apical end of the root is made at the floor of the crypt 
 and the root of the tooth is cut down to healthy tissue. 
 
 The Henahan surgical drill No. 4 is a very eflacient instrument for 
 the purpose of resecting the root. The resected end is now lifted out 
 of the crypt and the pocket thoroughly curetted with spoon-shaped 
 bone curettes. A large round bur is next used to smooth off the sharp 
 edges of the alveolar plate and to cut the end of the root and base of 
 the crypt down to healthy tissue. The cavity and root end is then 
 polished with a gold finishing bur or stone. 
 
 Many procedures have been resorted to in the past to secure a 
 protection for the exposed root end. Amalgam has been used with 
 more or less success. Encapsulation with gutta percha has been used. 
 Filling the apical end of the canal with gold has been tried. Filling 
 the whole canal with lead canal points and, after resecting, burnishuig 
 the lead over the end has been practiced. All of these methods have 
 met with objections. None has accomplished the full requirement of 
 completely sealing over the exposed root end. 
 
 Silver reduced over the exposed ends of the root seems to meet the 
 requirements of completely sealing the end of the root and does not 
 seem to interfere in any way with the process of repair. 
 
 The technic for reducing silver over the resected end is as follows: 
 the silver ammonium oxid is applied by suitable pipettes to the dry 
 resected end of the root. It is left there for from three to five minutes 
 after which a small amount of some reducing agent such as eugenol is 
 
652 EXTRACTION OF TEETH AND SURGICAL PROCEDURES 
 
 added and left for one minute. The excess is removed and^the resected 
 end burnished with a warm burnisher. The treatment may be repeated 
 until there is a dense black layer of silver deposited over the root end. 
 
 After the process of reducing silver over the exposed end of the root 
 is completed, the next question to decide upon is whether it is better 
 to bring the edges of the flaps together and suture or to pack the wound 
 and let the process of repair take place by granulation. Clinical 
 experience has shown that when the crypt has not been too extensive, 
 repair will take place more rapidly and with less pain when the wound 
 has been sutured than when left open, Horse hair or fine dermal suture 
 seems to be preferable to other materials for this purpose. Twenty 
 per cent solution argyrol used as a spray over the wound immediately 
 afterward and every twenty-four hours is indicated for postoperative 
 treatment. 
 
 In extensive cases when it is deemed best not to close the wound, 
 but to depend upon granulation for repair, iodoform gauze packed 
 lightly into the crypt for twenty-four to forty-eight hours and then 
 removed and the wound irrigated every twenty-four hours thereafter 
 with 5 per cent, salt solution until repair is complete has been the 
 treatment that has been followed in the author's clinics. 
 
 In checking up with the roentgenogram following the operation of 
 apicoectomy, the fact must not be overlooked that the roentgenogram 
 is merely the shadow of conditions present. In some cases it is not at 
 all probable that the regeneration of the new tissue will have the same 
 density as the original, consequently there may be for sometime a 
 difference in the density of the shadow and to the inexperienced this 
 may be misleading. 
 
 If this operation is to take its place in conservative dental practice, 
 the diagnosis of the case will play a greater role in the success or failure 
 than will the technic of the operation. In the final analysis, methods 
 of procedure in the operation play only a small part, and the methods 
 which are successful in one man's practice might be a failure in 
 another's. 
 
 After all, the final results are the determining factors. There are 
 four cardinal points to keep in mind: (1) a correct diagnosis of the 
 case; (2) recognition and maintenance of surgical asepsis; (3) elimina- 
 tion of the infection; (4) complete sealing of the end of the exposed root. 
 
 If these principles are carried out in every case, the results will take 
 care of themselves. 
 
CHAPTER XV. 
 
 PRINCIPLES OF ORTHODONTIA FOR THE GENERAL 
 PRACTITIONER. 
 
 By FREDERICK B. NOYES, B.A., D.D.S. 
 
 The author's purpose in the preparation of this chapter is to make as 
 clear a statement as possible of the fundamental principles upon which 
 the development of modern orthodontia has been based. It is not 
 expected that it will furnish a sufficient basis for the practice of ortho- 
 dontia, but that it will give the general practitioner a sufficiently clear 
 grasp of the subject for him to cooperate intelligently with the special- 
 ist to the very great atlvantage of his pat'ent. The general practi- 
 tioner usually has the opportunity to see cases in their early stages, at 
 the time when treatment should be begun and before so marked a 
 deformity has developed as to attract the attention of the laity. It 
 becomes a most important duty of the general practitioner to recognize 
 deviations from the normal developmental mechanism, so that during 
 the period of dentition normal occlusion may construct a normal 
 denture and a balanced face. It is also hoped that it may give a 
 sufficient statement of principles for the beginning of his study if he is 
 attracted to this field of dental science. 
 
 The development of modern orthodontia from the chaotic condition 
 of fifty years ago may fairly be said to have begun with the recognition 
 of normal occlusion as the basis of the science. For this the dental 
 profession is indebted to Dr. Edward H. Angle. Dr. Angle has defined 
 orthodontia as "that science which has for its object the correction of 
 mal-occlusion of the teeth," and he follows the definition immediately 
 by the statement that "occlusion is the basis of the science of ortho- 
 dontia." To combine these statements in one definition, orthodontia 
 might be defined as the science of occlusion and the art of correcting 
 mal-occlusion. One of the most important phases of the science of 
 occlusion is the study of the relation of the teeth to the development 
 of the face. 
 
 Occlusion. — Occlusion has been defined as the relation of the occlusal 
 inclined planes of the teeth when the jaws are closed. Normal occlu- 
 sion is the normal relation of these planes (Figs. 517, 518 and 519); 
 mal-occlusion is any deviation from the normal relation. The study 
 
 (653) 
 
654 PRINCIPLES OF ORTHODONTIA FOR THE PRACTITIONER 
 
 of normal occlusion from the orthodontic standpoint has led to a very 
 great development of our understanding of the meaning and importance 
 of the relation of the occlusal inclined planes of the teeth. This is 
 
 Fia. 517. — Typical occlusion. (BroomeU.) 
 
 Fig. 518. — Typicarocclusion; lingual view. (Cryer.) 
 
OCCLUSION— THE DEVELOPMENTAL MECHANISM 
 
 655 
 
 seen to be not merely the relation of cusps for the purpose of the 
 mastication of food, but a mechanism for the development of the 
 denture as a whole and the maintenance of it in oerfect function. 
 Occlusion becomes therefore not simply a means of mastication but a 
 developmental mechanism, through which all of the forces of function 
 are distributed in perfect balance, bringing about the normal develop- 
 ment of the bones of the face, the development of the denture as a 
 unit and the maintenance of each tooth in its perfect position. 
 
 Fig. 519. — Typical occlusion of molars; transverse view. (Cryer.) 
 
 OCCLUSION. THE DEVELOPMENTAL MECHANISM. 
 
 In considering occlusion as a developmental mechanism there are 
 two phases to be studied: first, the relation of the occlusal inclined 
 planes of the teeth, which receive and distribute the forces of function; 
 second, the forces of function, which are distributed through the 
 occlusal inclined planes of the teeth and bring about the normal 
 development of the supporting bones. A perfect denture and a normal 
 face therefore can only be developed by a perfect mechanism and 
 normal functional forces. If the relation of the inclined planes is 
 abnormal the forces of function will drive that tooth farther and 
 farther from its normal position and unless the forces of function are 
 normal in amount and in proper balance the supporting bones will not 
 be developed so as to carry the teeth to their proper relation to the 
 skull as a whole. 
 
 From the orthodontic standpoint the unit of the mechanism is a 
 single cusp. Each cusp may be represented as a four-sided pjTamid, 
 presenting four inclined planes: (a) mesio-buccal; (6) disto-buccal; 
 (c) mesio-lingual ; {d) disto-lingual. 
 
 For instance, the buccal cusp of the lower second bicuspid occludes 
 
656 PRINCIPLES OF ORTHODONTIA FOR THE PRACTITIONER 
 
 with the four cusps of the upper bicuspids, its mesio-buccal slope 
 antagonizing the disto-lingual slope of the buccal cusp of the upper 
 first; its mesio-lingual slope antagonizing the disto-buccal slope of the 
 lingual cusp of the upper first; its disto-buccal slope meeting the mesio- 
 lingual slope of the buccal cusp of the upper second bicuspid; and its 
 disto-lingual slope, the mesio-buccal slope of the lingual cusp of the 
 second bicuspid. It is therefore wedged in position both mesio-distally 
 and bucco-lingually. The more powerful the forces of function the more 
 perfectly the tooth is held in position. In the entire denture, therefore, 
 each cusp is the unit upon the perfect relationship of which is dependent 
 the perfect development and maintenance of the denture. No single 
 slope can be lacking without producing its modification in the support 
 of the entire machine. The problem of orthodontia becomes that of 
 establishing and maintaining the normal relation of these inclined 
 planes and the development of the normal forces which, distributed 
 in perfect balance, bring about the normal development of the features, 
 the perfect development of the masticating apparatus, the health of the 
 supporting tissues and constitute the most important factor in nature's" 
 method of cleansing the surfaces of the teeth by the mastication of 
 food, and consequently the prevention of caries. The beginning of the 
 study of orthodontia, therefore, must be the thorough and detailed 
 study of the relation of the inclined planes of the cusps of the teeth in 
 the fully developed and ideal denture. This is just as important for 
 the general practitioner as for the orthodontist, for the preservation 
 of the denture, the health of the supporting tissues and the prevention 
 of caries depend upon the preservation or restoration of the cusps of the 
 teeth and all their inclined planes. In the past the dental profession 
 has been too prone to be satisfied with "having teeth meet" without 
 regard to their cusp relationship. 
 
 The Development of the Denture. — ^Every practitioner of dentistry 
 should have as clear an idea as possible of the development of the 
 normal denture and a grasp of the complicated and interrelated forces 
 which are at work throughout this whole period of growth. The most 
 important factors in this process car best be studied from a series of 
 skulls from infancy to adult life. At birth the maxillary bones contain 
 the germs for all of the temporary teeth and all the permanent ones 
 except the second and third molars. The growth of these teeth in their 
 crypts exerts forces which are most important factors in the develop- 
 ment of the bones. Fig. 520 shows the maxillary bone of a child of 
 about one year, with the outer plate removed so as to expose the devel- 
 oping teeth. Fig. 521 shows one at about one and a half years. The 
 incisors have erupted and the growth of the unerupted cuspid and molars 
 exerts forces which tend to carry them in an occlusal and outward 
 
OCCLUSION— THE DEVELOPMENTAL MECHANISM G57 
 
 direction. The multiplication of cells in the formation of the roots 
 is a very important source of force which is transmitted from the 
 
 Fig. 520. — -Maxillae at about one year. 
 
 
 ^^^r ^^^ft '* "*'*>' ^^^^1 
 
 
 
 ^^^^^^^k^ 
 
 
 Fig. 521. — Maxillae at one and one-half years. 
 
 erupting teeth to the teeth already in position. In Fig. 522 from the 
 skull of a child in the second year the second temporary molars are seen 
 
 42 
 
658 PRINCIPLES OF ORTHODONTIA FOR THE PRACTITIONER 
 
 to be exerting forces which carry the incisors and cuspids occlusally 
 and outwardly. In this process the entire bone is undergoing rapid 
 transformations, increasing the distance from the floor of the nose to 
 the incisal edges of the teeth and the thickness of the mandible from the 
 lower border upward. In all of this period the action of all of the 
 muscles attached to and surrounding the bones exerts pressures which 
 help to mold this growth. At about three years the temporary denture 
 is complete. A comparison of Fig. 523 with the previous figures shows 
 the changes in the bone. During the period of the function of the 
 
 Fig. 522. — Maxillae in the second year, showing the relation of the erupting teeth. 
 Note the relation offjthe crypt of the second molar to the inferior dental canal. 
 
 temporary denture, from three to six years of age, while the teeth retain 
 their same relation to each other, they do not retain the same relation 
 to the skull. During this entire period they are constantly moving in 
 three dimensions of space, under the influence of muscular pressures 
 and forces exerted by the development of the permanent teeth. For 
 the present we shall consider only the forces exerted by the developing 
 teeth. Each permanent tooth is enclosed in a bony wall or crypt. 
 The multiplication of cells within this crypt pushes the wall back until 
 the resistance below is greater than the resistance above. Between 
 
OCCLUSION— THE DEVELOPMENTAL MECHANISM 659 
 
 five and six years of age the first permanent molars in their crypts exert 
 forces at the distal of the temporary denture, carrying all of the tem- 
 porary teeth forward and occlusally until room has been made for their 
 eruption. The second temporary molars guide them into relation 
 with their antagonists, but there is a period when they are coming into 
 occlusal relation, during which comparatively slight variations from 
 normal muscular pressures and action may cause their cusps to lock 
 abnormally and pervert the whole future development. The first 
 permanent molars should erupt and lock their cusps in normal relation 
 before the first temporary tooth is shed, and during the whole period in 
 
 Fig. 523. — The complete temporary dentition (about three years), showing the 
 relation of the developing permanent teeth. 
 
 which the permanent teeth are being substituted for the temporary 
 ones the first molars maintain the relation of the maxilla and mandible. 
 The importance of the normal locking of these teeth will therefore be 
 recognized at once. The abnormal relation not only shifts the position 
 of the mandible with reference to the maxilla but changes the balance 
 of muscular forces, which modify the development of the entire man- 
 dible. Every child should be examined when the first molars are 
 erupted to see that they lock their cusps in normal relation. 
 
 Between the ages of five and seven the most active growth is in the 
 region of the incisors, increasing the arc from cuspid to cuspid and 
 
660 PRINCIPLES OF ORTHODONTIA FOR THE PRACTITIONER 
 
 making the room required for the increased size of the permanent 
 incisors. While at four years the temporary incisors should be in 
 contact with each other on their mesial and distal surfaces, before 
 they are shed they should be standing wide apart with large spaces 
 between them. This is brought about by the development of the 
 permanent incisors and cuspids, and the relationship of the root of 
 
 Fig. 524. — Front view of the skull. Note the relation of the permanent incisors and 
 cuspids to each other and the roots of the temporary teeth. 
 
 the temporary cuspid to the tip of the developing permanent cuspid 
 is a most important factor. The normal relationship is shown in Fig. 
 524. As the permanent teeth develop they carry the temporary teeth, 
 alveolar process and all, in an occlusal and outward direction. The 
 loss of any factor in the relationship will result in the failure of the 
 proper distribution of forces. For instance a slight shifting of the 
 
OCCLUSION— THE DEVELOrMENTAL MECHANISM 001 
 
 temporary cuspid distally because of the loss of teuiporary molars, 
 ill whole or in part, will cause its root to lose the normal relation to the 
 permanent cuspid and the growth of the long cuspid root will not bring 
 about the normal development of bone in this region (Fig. 525). 
 
 Fig. 525. — Dentition in the eighth year. Note the position of the cuspids and 
 compare with Fig. 526. 
 
 Between the ages of six and eight the permanent incisors come into 
 place and take their normal relationship. Between the ages of eight 
 and eleven growth is most active in the region from the cuspid to the 
 second molar and is largely dependent on the development of the 
 bicuspids, which force the temporary molars occlusally, and on the 
 development of the second molars, pushing at the distal of the first 
 (Figs. 526, 527, 528 and 529). It is important to emphasize that dur- 
 
662 PRINCIPLES OF ORTHODONTIA FOR THE PRACTITIONER 
 
 ing the entire period of development the teeth are moving under the 
 influence of developmental forces and are being carried into new posi- 
 tions with relation to the skull by the growth of bone. The process is 
 dependent upon the maintenance of each tooth until the normal time 
 for its loss, and the extraction of a tooth does not make more space but 
 
 Fig. 526. — Dentition in the eleventh year. Note the growth of the cuspids and 
 bicuspids. The second molar is about to erupt. 
 
 less. It would seem unnecessary to emphasize the importance of the 
 temporary molars. Nature provides a slightly greater mesio-distal 
 diameter of the temporary molars as compared with the bicuspids so 
 as to allow space for their eruption. If the temporary molar is pre- 
 maturely lost the second permanent molar will crowd the first molar 
 mesially before the bicuspid can take its place. 
 
OCCLVmOM—TlIl^ DEVELOPMENTAL MECHAnISM 663 
 
 After the eruption of the second molars and bicuspids the movement 
 of all of the teeth in the denture should continue under the influence 
 of muscular pressure and the growth of the third molars. Compare 
 in Figs. 527 and 529 the distance from the tip of the upper incisor root 
 to the floor of the nose and of the lower incisors and cuspids to the 
 lower border of the mandible, between the ages of thirteen and a fully 
 developed adult. This growth seems to be dependent upon the vigor 
 of muscular action which stimulates cell activity in the bone not only 
 by mechanical influence but by the increase of blood circulation. 
 
 
 
 
 
 ^^^^^^^H 
 
 w ^ ^^^^1 
 
 
 w -"^ ^^ ^^^1 
 
 
 l[»-'^^f|^' .- -*^' ; ^H 
 
 
 ^ y J \ ^^ - ^l^ 
 
 ^■^'^"'^^^^ 
 
 
 
 ^'"^ ■*- jJ| f i ^^^^1 
 
 
 ^ ''^A' f-S i^ .^H 
 
 
 B^^^^jH 
 
 Fig. 527. — Dentition in the thirteenth year. Note the relation of the bicuspid 
 crown to the roots of the lower temporary molar. 
 
 The Forces Governing Occlusion. — The forces governing occlusion 
 are defined as those forces which tend to guide the teeth into their 
 normal relation to each other and their normal position with refer- 
 ence to the skull. They may be divided into two classes — potential 
 forces and dynamic forces. The potential forces are: (1) the occlusal 
 inclined planes of the teeth, which distribute through the opposing 
 planes the forces of function and growth; (2) the contact of approxi- 
 mating surfaces of the teeth, which distribute through the entire den- 
 ture the forces of developing and unerupted teeth; (3) the resultant 
 
664 PRINCIPLES OF ORTHODONTIA FOR THE PRACTITIONER 
 
 harmony in the size and relation of the arches. Through these poten- 
 tial agencies the dynamic forces are distributed. 
 
 The dynamic forces are: (a) cell activity; (6) muscular action and 
 pressure: (1) respiration; (2) deglutition; (3) mastication; (4) speech; 
 (5) expression; (6) atmospheric pressure; (7) attention and muscular 
 tone. 
 
 Fig. 528. — The dentition of a young adult. The third molars have not erupted. 
 (About fifteen years.) 
 
 (a) Cell Activity. — It has long been known that in the multiplication 
 of cells very considerable forces are generated. The sprouting seed 
 forces its way through the earth; growing rootlets, entering between 
 stones, force them apart. The forces generated by the multiplication 
 of plant cells have been studied and more or less accurately measured 
 
OCCLUSION— THE DEVELOPMENTAL MECHANISM 005 
 
 by botanists. The same forces in the niukiphcation of c-ells in the 
 growth of the tooth germ and in the development of the tooth roots 
 are important sources of dynamic energy in the development of the 
 denture. Not much is known of their nature, but they are evidently 
 dependent upon general nutrition and vital energy. We see many 
 instances, especially in frail individuals, in which the cellular activities 
 do not manifest sufficient energy to exert their normal forces. 
 
 Fig. 529. — Adult dentition. Note the distance from the apices of the incisors to 
 the lowest border of the mandible and the floor of the nose. 
 
 (6) Muscular Action and Pressure. — All of the forces generated by 
 muscular action in the performance of function are distributed through 
 the potential forces and the growth of the supporting bones is a response 
 to these mechanical stimuli. The positions which the teeth come to 
 occupy are dependent upon the vigor and balance of these functions. 
 Failure of normal action or abnormal balance of action results in pro- 
 portional underdevelopment of bone and modification of the dentm-e, 
 and may lead to the perversion of the potential forces. It may be 
 worth while to examine somewhat in detail the action of the individual 
 functions. 
 
666 PRINCIPLES OF ORTHODONTIA FOR fHE PRACflTlONm 
 
 1. Bespiration. — Respiration is probably the most important func- 
 tion with reference to the development of the denture, for it is in con- 
 stant action. Nature intended man to breathe through the nose. In 
 order to exert its normal influence respiration must be not only normal 
 in performance but sufficiently vigorous in action. In forced respira- 
 tion the muscles attached to the hyoid bone are vigorously contracted, 
 drawing the tongue upward and forward, forcing it against the lingual 
 surfaces of the teeth and the supporting bones. This is one of the 
 most important factors in the development of the dental arches. The 
 author has been amazed at the instruction given by physical directors 
 in high schools in training boys for track teams to have them breathe 
 through the mouth. 
 
 2. Deglutition. — The normal individual who breathes through the 
 nose swallows about once in two minutes, night and day. In this act 
 the muscles attached to the hyoid bone are also contracted, and pres- 
 sures are exerted as in forced respiration. One need only to close the 
 lips and swallow voluntarily to be conscious of the pressures exerted. 
 When breathing is carried on normally the secretions collect in the 
 mouth and are expelled by swallowing, so that this impulse to growth is 
 repeated at frequent intervals, night and day, and becomes an impor- 
 tant factor in development. If respiration is carried on through the 
 mouth the secretions are evaporated by the air, swallowing is omitted 
 and this impulse to growth is lost, with consequent lack of development 
 in the dental arches. 
 
 3. Mastication. — ^While mastication is the first functional force to be 
 thought of in connection with the development of the dental arches it is 
 undoubtedly not the most important, for it is most intermittent in 
 action. On the other hand its action has the most direct influence 
 upon the bone of the alveolar process, stimulating both its blood supply 
 and its cell activity. It is the grinding motions of the teeth which 
 exert the most influence in modifying the form of the dental arches. 
 In this action the lower teeth are forced against the lingual slopes of the 
 buccal cusps of the upper teeth in such a way as to tend to widen and 
 round the dental arches. This is markedly seen in the study of the 
 relation of the diet to the form of the denture in different races. The 
 meat-eater tends to have a long narrow arch; the vegetable-eater, a 
 broad, round arch. Many cases of mal-occlusion would never develop 
 if the child ate the shredded wheat biscuit and drank the cream instead 
 of soaking the cereal and swallowing it without mastication. 
 
 4. Speech. — Space will not permit the detailed examination of the 
 influence of speech on the development of the denture and the bones of 
 the face, but it exerts an important influence, especially in the forces 
 
OCCLUSION— THE DEVELOPMENTAL MECHANISM 667 
 
 acting upon the labial and buccal surfaces of the teeth and bones. 
 It is interesting to note that anthropologists have long since pointed 
 out that the development of the chin begins with the power of speech, 
 and all forceful speakers have a well-developed chin. Training in 
 elocution sometimes becomes a help in the correction of mal-occlusion. 
 
 5. Expression. — Most mental states are accompanied by action of 
 the facial muscles, which react through the potential forces in the 
 molding of the bones. Certain mal-occlusions are undoubtedly related 
 to habitual mental states, and in a very literal way every thought molds 
 not only the expression but the framework of the face. 
 
 6. Atmospheric Pressure. — Atmospheric pressure is closely related 
 to the function of deglutition and nasal breathing. In swallowing with 
 the lips closed the air and liquid contents of the mouth cavity are 
 expelled, the soft palate is brought into contact with the posterior 
 portion of the tongue, and, as the muscular action relaxes, a partial 
 vacuum is produced, which exerts a downward pressure upon the roof 
 of the mouth, a pressure of the lips against the labial surfaces of the 
 incisors, and pressure against the lingual surfaces of the buccal teeth. 
 In nasal respiration, inhalation and exhalation, in proportion to their 
 vigor, produce alterations of atmospheric pressure in the nasal spaces 
 and their accessory sinuses, which, exerted against the walls of these 
 cavities, bring about their normal development. 
 
 7. Attention and Muscular Tone. — In recent literature we have often 
 seen the statement that the occlusal surfaces of the teeth are not held 
 in contact. This statement is literally true of the idiot but not of the 
 normal individual. In proportion as the attention is dhected and 
 concentrated the teeth are brought firmly in contact. To demon- 
 strate this, one need only see a child sitting in a dreamy state with the 
 lips parted and jaw dropped, and speak to him quickly or sharply and 
 see the lips tighten and the teeth come together with a click. The lack 
 of concentration arid attention as a general state is responsible for a 
 lowering of muscular tone, not only in the muscles of the face, but of 
 the entire body. It is important to remember that we cannot expect 
 to have the normal muscular tone in the muscles which mold the 
 denture if it is absent in the general muscular system. 
 
 In the consideration of the forces governing occlusion, therefore, we 
 see in the potential forces a machine which, actuated by the power 
 generated by the dynamic forces, molds the entire development of the 
 features. In order that the face may become the expression of the 
 individual and an index of his personality, we must maintain through 
 the developmental period the perfect action of the machine and the 
 normal balance of the forces. 
 
668 PRINCIPLES OF ORTHODONTIA FOR THE PRACTITIONER 
 
 ETIOLOGY OF MAL-OCCLUSION. 
 
 1. Mechanical. 
 
 (a) Loss or perversion of the potential forces governing occlusion. 
 
 (b) Premature loss of temporary teeth in whole or in part. 
 
 (c) Prolonged retention of temporary teeth. 
 
 (d) Loss or absence of permanent teeth. 
 
 (e) Improper or imperfect restorations. 
 
 2. Abnormal functional habits. 
 
 (a) Abnormal breathing and lack of sufficient vigor of breathing. 
 (6) Loss of normal swallowing. 
 (c) Snuffles and similar habits. 
 
 3. Abnormal nervous habits. 
 
 (a) Thumb sucking. 
 
 (b) Lip and tongue habits. 
 
 4. Psychological. 
 
 (a) Associated with mouth-breathing. 
 
 (b) Mental states. 
 
 5. Pathologic conditions. 
 
 (a) Destruction of supporting tissues. 
 (6) Pathologic growths. 
 
 6. Accidents and injuries. 
 
 (a) Mutilations. 
 
 (b) Burns. 
 
 7. Freaks and deformities. 
 
 From the study of the development of the normal denture it is 
 apparent that the causes of mal-occlusion are but the perversion of 
 nature's plan. The purposes of this chapter do not allow for the 
 elaboration of these in detail. 
 
 NOMENCLATURE AND CLASSIFICATION. 
 
 Seven words and their combinations will describe accurately any 
 position that a tooth out of harmony with the line of occlusion may 
 occupy. These terms are generally accepted and used in the literature 
 of orthodontia. 
 
 1. Labial or buccal occlusion. 
 
 2. Lingual occlusion. 
 
 3. Mesial occlusion, 
 
 4. Distal occlusion. 
 
 5. Infra occlusion. 
 
 6. Supra occlusion. 
 
 7. Torso occlusion. 
 
NOMENCLATURE AND CLASSIFICATION 669 
 
 Two or even three of them may be combhied in the description of the 
 position of a single tooth. For instance, a canine nearer the median 
 line and farther to the labial than normal, and at the same time turned 
 on its axis, would be said to be in mesio-labio-torso occlusion. 
 
 Classification. — The Angle classification has undoubtedly been one of 
 the very important factors in the development of orthodontia, since for 
 the first time in the history of the subject it gave a scientific grouping 
 of cases upon which the procedures in treatment could be based. The 
 Angle classification is great because it is not an arbitrary grouping of 
 cases by the mesio-distal relation of two teeth, but the mesio-distal 
 relation of the first permanent molars is recognized as the most impor- 
 tant single factor in the development of the denture, and therefore it is 
 made the basis of the grouping. Whatever modification there may be 
 in it in the future it will undoubtedly remain fundamentally unchanged. 
 
 Before giving the classification of mal-occlusion I want to quote this 
 paragraph from Dr. Angle's book, stating the basis of classification. 
 He says: 
 
 "These classes are based on the mesio-distal relations of the teeth, 
 dental arches and jaws, which depend primarily upon the positions 
 mesio-distally assumed by the first permanent molars on their erupt- 
 ing and locking. Hence, in diagnosing cases of mal-occlusion we must 
 consider, first, the mesio-distal relations of the jaws and dental arches 
 as indicated by the relation of the lower first molars with the upper 
 first molars — the keys to occlusion; and second, the positions of the 
 individual teeth, carefully noting their relations to the line of occlusion. 
 
 Class I. — Arches in normal mesio-distal relations, as indicated by 
 the first molars. 
 
 Class H. — Lower arch distal to normal in its relation to the upper 
 arch, as indicated by the first molars. 
 
 Division H. — Bilaterally distal, protruding upper incisors. Pri- 
 marily, at least, associated with mouth-breathing. 
 
 Subdivision. — Unilaterally distal, protrudmg upper incisors. Pri- 
 marily, at least, associated with mouth-breathing. 
 
 Division. — Bilaterally distal, retruding upper incisors. Normal 
 breathers. 
 
 Subdivision. — Unilaterally distal, retruding upper incisors. Normal 
 breathers. 
 
 Class HI. — Lower arch mesial to normal in its relation to upper 
 arch, as indicated by the first molars. 
 
 Division . — Bilaterally mesial. 
 
 Subdivision. — Unilaterally mesial. 
 
 Every practitioner of dentistry should be thoroughly familiar with 
 this classification and able to recognize any mal-occlusion at once, and 
 
670 PRINCIPLES OF ORTHODONTIA FOR THE PRACTITIONER 
 
 name the divisions or subdivisions to which it belongs. It is so 
 simple and so easily grasped that a very little consideration will enable 
 anyone to do this. 
 
 FUNDAMENTAL PRINCIPLES OF TREATMENT. 
 
 Growth Not Tooth Movement. — The first great fundamental principle 
 that must be clearly grasped in considering treatment is that during 
 the entire period of growth the teeth are moving in three dimensions 
 of space by the development of bone under the influence of natural 
 forces. This movement in no way differs from ideal movement by 
 artificial force, and the tissue changes in the two are identical. The 
 author could show in sections identical reactions of bone to natural 
 forces and to properly controlled and directed artificial forces exerted 
 upon the teeth by mechanical appliances. The teeth are not, or should 
 not be, pushed through the tissues, but are carried by tissue activity into 
 their normal positions and relations. 
 
 Treatment must force, or, better, enable nature to carry out her ideal 
 or intention, and so teeth should move in the direction and the manner 
 of the normal process. To illustrate, a dental arch is to be widened at 
 the first bicuspids. While the teeth are moving buccally they are also 
 moving occlusally. Incisors are to be moved labially, but while they 
 are moving in that direction they are also moving incisally, increasing 
 the distance from the floor of the nose. It has been the tendency to 
 think of tooth movement in terms of two dimensions. It should be 
 thought of in three dimensions. The tissues respond better and more 
 easily to stimulation to growth in their normal directions than to 
 forces opposed to them. 
 
 In natural processes growth is intermittent. A period of rapid 
 advance is followed by one of organization and the gathering of forces 
 for a new advance. In the stimulation of growth by artificial forces 
 the stimulus should not be repeated more rapidly than the tissue can 
 organize and prepare for a new growth. Time was when orthodontic 
 appliances were tightened every day or two. No tissue could maintain 
 such a pace. 
 
 Whatever the form of appliance used to generate the force the force 
 must be positive in character, constant in direction, moderate in amount 
 and limited in range of action. Inflammation is at once set up in the 
 tissue if the tooth is allowed to move back and forth or if the force 
 is constantly changing direction. It is surprising how quickly soreness 
 can be set up when these conditions occur. 
 
 Time of Treatment. — As soon as a definite fault in the mechanism 
 of development which makes its further normal action impossible is 
 
FUNDAMENTAL PRINCIPLES OF TREATMENT G71 
 
 discovered it should be corrected, so that the natural forces may con- 
 tinue normal development. Mal-occlusion in the temporary denture is 
 comparatively rare, but if it occurs it should be corrected at once and 
 every effort made to establish and maintain the normal developmental 
 mechanism. ^Yhile the author is heartily in favor of early treatment 
 the most common mistake that is being made at present is the wearing 
 of inefficient appliances continuously for long periods. There are 
 definite periods in which certain things should be done. The work 
 should be accomplished rapidly with a positive and efficient appliance, 
 the results maintained, and then nature given a chance to carry on her 
 work under the normal influences of growth. 
 
 Periods of Active Treatment. — In the development of the denture there 
 are certain periods of danger, and especially active gro-^-th. These 
 should be the periods of active treatment. 
 
 1. The Eruption of the First Permanent Molars. — If when these 
 teeth erupt they do not lock normally, appliances should be placed 
 on the teeth and the necessary movements accomplished to lock them 
 normally. They should then be retained in their normal relation until 
 their cusps have been firmly locked, when all appliances should be 
 removed and nature allowed to proceed. 
 
 2. When the Permanent Incisors Erupt. — If the development in this 
 region is deficient appliances should be placed, the necessary develop- 
 ment accomplished and retained for a comparatively short time and 
 nature allowed to proceed again. 
 
 3. While the Bicuspich and Second Molars are Erupting. — ^This 
 should be the final period of treatment. Very often work during this 
 period is commenced too soon and as a result it is necessary to wear 
 appliances for a long time, waiting for the eruption of some tooth. 
 
 Time of Completion of Treatment. — All orthodontic treatment should 
 be completed by the time the second molars are in full occlusion, but 
 because of the deficiency of the forces which should cause the develop- 
 ment in the width of the arches it is often necessary to use some simple 
 method of maintaining the width for a long time. 
 
 Means of Treatment. — ^There are tw^o means of treatment at the 
 command of the orthodontist: 
 
 1. The use of artificial forces derived from mechanical appliances. 
 
 2. The development and stimulation of natural forces of function. 
 In the past it is certainly true that too much attention and reliance 
 
 have been placed on the first and too little on the latter. It is much 
 easier to make an appliance to replace or supplement a deficient natural 
 function than to develop it to normal power. During active treatment 
 positive and efiicient appliances should accomplish definite results as 
 rapidly as possible. During retention and between periods of active 
 
672 PRINCIPLES OF ORTHODONTIA FOR THE PRACTITIONER 
 
 treatment attention should be given to the development of the natura. 
 forces, for it must be remembered that throughout life the teeth remain 
 only in the position in which all of the forces to which they are sub- 
 jected are balanced. 
 
 Complications of Treatment. — Caries. — Caries during orthodontic 
 treatment is a serious matter and requires the cooperation of the 
 orthodontist, the dentist, the parents and the patient. With reason- 
 able cooperation of all there is no reason for damage to the teeth. 
 With the modern appliance the teeth can be kept clean with reasonable 
 effort. Three things are most important: 
 
 1. The care of the teeth by the dentist before treatment and in 
 intervals between active treatments. 
 
 2. The systematic instruction and training of the patient in cleansing 
 the mouth. 
 
 3. The insistence upon carrying out of the instruction. 
 
 Loss of Dental Pulys. — Pulps may be destroyed by unreasonable and 
 improper application of force through orthodontic appliances, but it 
 seems equally certain that reasonable use of appliances will not endanger' 
 the life and activity of the pulp. Many cases of pulp destruction during 
 treatment are in no way related to the treatment. In the last few 
 years the author has seen several instances in which pulp destruction 
 occurred during treatment in teeth that had never had any artificial 
 force applied to them and the occurrence could not possibly be referred 
 to the treatment. 
 
 Inflammation of the Gums. — Hypertrophic inflammation of the gum 
 margins caused by filth is not uncommon in children from eight to 
 twelve years of age. The same condition sometimes occurs during 
 orthodontic treatment. It is caused by lack of proper mouth hygiene, 
 but may be augmented by sloven technic in the application of bands. 
 When it occurs the bands must be removed and the conditions reduced. 
 If it cannot be prevented when the appliances are replaced the treat- 
 ment should be abandoned until the patient can be made to keep the 
 mouth clean. 
 
 Absorption of Permanent Tooth R,oots. — ^This is probably due to 
 improper application of force, the attempt to move teeth in an impos- 
 sible direction or improper control of force. Such absorptions occur, 
 however, in rare instances when there has been no orthodontic treat- 
 ment, and caution should be used in blaming the treatment for it 
 without good evidence. When it is caused by the orthodontic appliance 
 the author believes that it is usually the result of lack of constancy in 
 the direction of the force, or by forcing the root against some such 
 impossible resistance as the root of another tooth. 
 
PRINCIPLES OF ORTHODONTIC TECHNIC 673 
 
 PRINCIPLES OF ORTHODONTIC TECHNIC. 
 
 The first requirements in orthodontic procedure or examination are : 
 
 1 . Perfect models from accurate plaster impressions which show not 
 only the teeth and their occlusal relations but the details of bone struc- 
 ture as far as the attachments of the soft tissues will permit. 
 
 2. Photographs of the face showing correctly the features in repose, 
 both front view and profile, and 
 
 3. Roentgenograms showing the roots of the teeth and unerupted 
 teeth. Instruction in technical methods is beyond the scope of this 
 chapter. For such instruction those interested are referred to the 
 standard text-books. 
 
 The record of the original conditions is the foundation of all treat- 
 ment, and no adjustment should ever be made without first determining 
 the distance and direction in which the tooth has been moved and 
 exactly what is to be accomplished by the adjustment contemplated. 
 If fewer adjustments were made and each were studied more carefully 
 orthodontic treatment would be accomplished faster and better. 
 
 Soldering. — Orthodontia has developed a soldering technic which is 
 fundamentally different from that used generally in dentistry. In 
 dentistry large masses of solder are used to unite masses of metal often 
 widely separated. The principles of orthodontic soldering are: 
 
 1. Perfect contact of the metal surfaces to be united. 
 
 2, Perfect union with the smallest amount of solder. Strength 
 depends upon perfection of contact and area of surface united. 
 
 Sloppiness in soldering is a common cause of inefficiency in an 
 appliance. For instruction in soldering technic the student is referred 
 to text-books on orthodontia, but the beginner must realize that he is 
 to master a new set of principles not generally used in dentistry. 
 
 Appliances. — It is not the appliance but the intelligence with which 
 it is used that accomplishes results in orthodontia. Undoubtedly 
 results may be obtained with very clumsy and inefficient appliances 
 used with skill and knowledge. The rational method is to find the 
 appliance that will furnish the most positive and efficient force under 
 the most perfect control and then learn to apply it with knowledge, 
 judgment and skill. Satisfactory results will never be attained by using 
 a different appliance in each case. 
 
 In the author's opinion the ribbon arch and bracket band appliance 
 possesses the above requirements to a greater degree than any instru- 
 ment yet devised, but it will never be used with success except by those 
 who exercise the most painstaking accuracy and skill in its adjustment 
 and the highest degree of knowledge and judgment in its application. 
 An inefficient appliance is less dangerous in careless and inexperienced 
 43 
 
674 PRINCIPLES OF ORTHODONTIA FOR THE PRACTITIONER 
 
 hands than an efficient one, for it will produce results so slowly that 
 undesirable results may be noted before serious damage has been done 
 while improper adjustment of an efficient instrument produces bad 
 results with the same precision that proper adjustment does in bringing 
 about the desired end. 
 Retention. — ^There are three periods in retention: 
 
 1. Fixation. 
 
 2. Antagonizing tendency to return to old position. 
 
 3. Establishment of the normal balance of forces. 
 
 After teeth have been moved from a position of mal-occlusion into 
 harmony with the line of occlusion they must be fixed in the new posi- 
 tion for a very brief period — just long enough for the primary readjust- 
 ment and reorganization of the supporting tissues. This is best accom- 
 plished by allowing the working appliance to remain in a state of rest 
 for a short time. 
 
 If appliances are removed the teeth will rapidly return to their 
 original positions. The retaining device should antagonize this tend- 
 ency to return, but limit the freedom of the teeth in no other way, 
 leaving them exposed to all the action of the normal forces. If in 
 the new position the forces are balanced the supporting tissue will 
 rapidly be completely reorganized. The obtaining of the normal 
 balance of force is often the most difficult problem, especially when 
 it involves the breaking up of old and long-established abnormal 
 functional habits and the establishment of new and normal ones. 
 
 In concluding this chapter, which has sought to give the general 
 practitioner an elementary statement of the fundamental principles 
 of orthodontia, it may be said that orthodontia is a part of dentistry 
 only in the sense that it has to do with the teeth and mouth. Dentistry 
 is the study and treatment of the diseases of the mouth and their 
 relation to the health of the individual. Orthodontia is the study of 
 the development of the denture and the correction of deviations from 
 normal. Dentistry has to do with pathologic processes, orthodontia 
 with normal developmental processes. Orthodontia is in no sense a 
 part of prosthetic dentistry, and the fundamental principles upon which 
 its practice is based are not involved in the practice of dentistry. If 
 the general practitioner can grasp this idea there will be better coopera- 
 tion between the dentist and the orthodontist for the good of the 
 patient and humanity. 
 
CHAPTER XVI. 
 
 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY. 
 
 By KURT H. THOMA, D.M.D. 
 
 One of the greatest aids in examination of the mouth and teeth, 
 in diagnosis of oral lesions and in the discovery of obscure defects 
 and abnormalities, is the roentgen method. Its usefulness has 
 increased to such an extent that today it is a necessary part of modern 
 dental practice, not only for the purpose of examination but also to 
 check up the result of mechanical procedures and surgical treatment. 
 The diagnosis from a roentgen picture alone, however, should not 
 be relied upon, it does not replace any of the other means of exami- 
 nation, but should be considered in conjunction with other methods 
 of diagnosis. 
 
 The value of the diagnosis made from a roentgen picture depends 
 of course, entirely upon correct interpretation and, therefore, on the 
 experience and skill of the roentgenologist. It would seem advisable, 
 on this account, for the general practitioner to refer his patient to 
 the roentgen specialist, who would naturally have a much wider 
 experience and a specialized training in this branch of dentistry. 
 On the other hand the specialist cannot always have a full knowledge 
 of the problem which is referred to him, and he cannot, therefore, 
 always produce the picture best suited to the case in question. There 
 is no doubt whatever that the patient, as a rule, will receive greater 
 benefit if the dentist, for routine work, makes his own roentgen 
 pictures, except in cases of an extensive nature and for unusual con- 
 ditions requiring extraoral exposures. A roentgen machine large 
 enough to take good dental films in from three to five seconds would 
 therefore be sufficient for his needs and, being close at hand, would 
 lead to more frequent use than if the patient had to be sent to someone 
 else. The possibility of taking roentgenograms promptly when the 
 need arises and of getting the result in a short time enables the dentist 
 to use this method extensively for routine work. 
 
 ROENTGEN NOMENCLATURE. 
 
 There are a great many roentgen terms in use, and there has, so 
 f9,r, been no st9,nda,rdiza,tion in dental literature. In this book the 
 
 (075) 
 
676 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 terms employed are those which have been adopted by the American 
 Roentgen-ray Society, October 1, 1913, and accepted by the Journal 
 of the American Medical Association. The Committee on Nomen- 
 clature of the American Institute of Dental Teachers also recom- 
 mends their use: 
 
 Roentgen Ray. — A ray discovered and described by Wilhelm Conrad 
 Roentgen. 
 
 Roentgenology. — ^The study and practice of the roentgen ray, as 
 applied to medical science. 
 
 Roentgenologist. — One skilled in roentgenology. 
 
 Roentgenogram. — A shadow picture produced by the roentgen ray 
 on a sensitive plate or film. 
 
 Roentgenograph (verb). — ^To make a roentgenogram. 
 
 Roentgenography. — ^The art of making roentgenograms. 
 
 Roentgen Diagnosis. — A diagnosis made by means of roentgeno- 
 grams. In addition to these terms the following words have been 
 made use of, the three latter having been supplied by Dr. Ottolengui 
 to meet a long felt need adequately to express certain properties: - 
 
 Radiahility. — ^The property of an object to transmit the roentgen 
 ray. 
 
 Radioparent (Radioparency) . — Offering no barrier to the roentgen 
 ray. 
 
 Radiolucent (Radiolucency) . — Offering slight resistance to the 
 roentgen ray. 
 
 Radiopaque {Radiopacity) . — Impervious to the roentgen ray. 
 
 THE PRODUCTION OF ROENTGEN RAYS. 
 
 It needs but little practice to manipulate a roentgen machine, 
 detailed instructions being always furnished by the manufacturers. 
 The way to produce suitable roentgen rays for the best results is 
 soon learned, once the principle is thoroughly understood. The first 
 requirement is to produce the most suitable type of ray. The quality 
 of the rays varies according to the vacuum in the gas tube and accord- 
 ing to the temperature of the filament in a Coolidge tube. The more 
 perfect the vacuum in a gas tube and the colder the filament in a 
 Coolidge tube the greater the resistance offered to the current passing 
 through them. A tube with high resistance emits "hard rays" while 
 a tube with low resistance generally gives what is called "soft rays." 
 The quality of the rays, therefore, can be altered at will by changing 
 the resistance of the tube. In the gas tube (Fig. 530) this is accom- 
 plished by letting a very weak current pass through the regulating 
 chambers. The heat generated produces gases from the chemicals 
 
PRODUCTION OF ROENTGEN RAYS 
 
 677 
 
 contained therein, which pass into the tube, lowering the vacuum and 
 decreasing the resistance. When at rest the vacuum returns to its 
 normal state. New tubes have recently been constructed which, 
 together with other improvements, "come back" in a comparatively 
 
 Fig. 530.— Gas tube. 
 
 Fig. 531. — Nitroken tube. 
 
 "•PI---"-' 
 
 "^ -^!t=E=p-«|.- 
 
 FiG. 532.— Coolidge tube. 
 
 short time to their original vacuum, which is very much higher than 
 in the old-style gas tube. The advantage of this is that the same 
 tube, by proper adjustment before each exposure, can be used for the 
 production of either hard or soft rays. The regulator is said to be 
 
678 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 designed so that overreduction is impossible. An example of this 
 tube is the Nitroken tube shown in Fig. 531. In the Coolidge tube 
 (Fig. 532) the resistance is changed by heating the filament in the 
 cathode by means of a low-tension current. A rheostat is used to 
 produce the change which affects the temperature. At a certain 
 temperature of the filament not more than a certain number of milli- 
 amperes can pass through the tube, regardless of how high the output 
 of the machine. The penetration of the rays increases as the voltage 
 is increased above that needed for the current value. 
 
 Soft rays are of a bluish-green color and have little penetrating 
 quality. The hard rays, which have a much greater penetrating 
 power, are suitable for bone and dental work. Too much penetration, 
 however, gives a picture with very little contrast, a fault which renders 
 it worthless for making a diagnosis of pathological conditions, which 
 often cause only a slight difference in the radiability of the tissues. 
 
 METHOD OF TAKING ROENTGEN PICTURES OF THE 
 
 TEETH. 
 
 Roentgenograms of the teeth may be taken by either the extra-oral 
 or the intra-oral methods. The former is used in making a general 
 survey, so as to get an idea of the relation of the neighboring structures 
 to the teeth and pathological conditions which may affect them. 
 Malposed teeth, extensive bone infection, cysts and fractures are not 
 infrequently overlooked when only small dental films are used. The 
 latter, however, show details of the teeth and alveolar structures 
 with much greater accuracy for the simple reason that they can be 
 placed closer to the tissue which is to be investigated and because 
 there is less distortion and fewer superimposed shadows. The large 
 size (2| X 3") intra-oral films are very useful for more extensive pictures 
 of the tissues of the upper jaw, especially in the anterior region, which 
 cannot be clearly reproduced in an extra-oral plate or film. The film 
 is placed between the teeth, as far back as possible, with the sensitive 
 side directed against the upper jaw. The same method is sometimes 
 useful for the lower jaw, especially to locate calculi or foreign bodies 
 in the fioor of the mouth. For the latter the head-rest of the chair 
 must be so adapted that the patient can tip the head way back, allow- 
 ing sufficient space to get the right position of the tube in front of the 
 patient. The sensitive side of the film is placed downward toward 
 the part to be roentgenographed. The small dental films are most 
 generally used in operative dentistry. A new dental film put on 
 the market recently by the Buck X-Ograph Company, St. Louis, 
 Missouri can be recommended very highly. It is far superior to 
 
METHOD OF TAKING ROENTGEN PICTURES OF TEETH 679 
 
 the original Eastman films on account of its improved method of 
 packing. The rounded corners make it possible to get the film much 
 closer to the tissue, and when once placed they are less liable to slip 
 from their original position than the Eastman films. 
 
 For taking the roentgen picture the patient is seated in the chair. 
 The position of the head makes no great difference, although it is 
 advisable to have all patients in the same position, as this makes it 
 possible to develop a routine and so get uniform results. The author 
 always has the patient placed so that the lower border of the mandible 
 lies in a horizontal plane. 
 
 Elongation of picture 
 
 -Ray 
 
 Fig. 533 
 
 Fig. 534 
 
 Finding the Correct Angle. — The angle at which the rays are directed 
 toward the object is of the greatest importance and varies consider- 
 ably, not only for different teeth but for different patients. The 
 anatomic make-up of the inside of the mouth shows many variations, 
 which govern the placing of the film. If the patient has a high vault 
 and a long alveolar process the film can be placed almost parallel with 
 the teeth in the upper jaw, while in a mouth with a flat palate the film 
 may be at a decided angle to the teeth. The question then arises 
 whether the rays should be directed vertically to the teeth or to the 
 film. Fig. 533 shows the result of directing the rays vertically to the 
 
680' ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 object (22 mm.), producing an elongation (24 mm.). Fig. 534 shows 
 the rays directed vertically to the film, which foreshortens the picture 
 (IS mm.). The rays should be directed vertically to an imaginary 
 plane lying exactly half-way between the plane of the object and the 
 plane of the film. This gives a picture of natural size (22 mm.) 
 (Fig. 535). 
 
 This principle applies to all single-rooted teeth, both m the upper 
 and lower jaws. Multi-rooted teeth present a more complex problem. 
 If it is necessary to get a picture showing the exact condition and 
 correct length of all the roots it is often necessary to take two or three 
 pictures from different points of view. A picture is taken of each 
 root, the angle being calculated as if a single rooted tooth were being 
 roentgenographed. In addition one must choose a direction which 
 prevents overlapping. The teeth which present the greatest diffi- 
 
 Imaginary plane 
 Plane offilnA . 'Plane of object 
 
 Fig. 535 
 
 culties are the upper molars, especially the first and second molars. 
 An entirely different angle is necessary for the palatal root and the 
 buccal roots. For the former the rays are directed from a high posi- 
 tion of the tube, which gives a foreshortening of the buccal roots 
 and a clear picture of almost the entire palatal roots (Figs. 536 and 
 537). The buccal roots are taken with a more horizontal direction 
 of the rays, Figs. 538 and 539, and as there is nearly always super- 
 imposition of the palatal over one of the buccal roots, it is necessary 
 to take one picture from a mesial aspect to isolate the disto-buccal 
 root, and one from a distal point of view bringing out the mesio- 
 buccal root, in case it is not fused to the palatal one (Figs. 540 and 
 541). This method also overcomes another anatomic difficulty, which 
 often occurs. This is the zygomatic process, which may, at a certain 
 angle, obscure the picture (Fig. 542). 
 
METHOD OF TAKING ROENTGEN PICTURES OF TEETH 681 
 
 The upper bicuspids frequently present special problems. If 
 roentgenographed from a straight buccal aspect it frequently appears 
 as if there were but one root canal and in first bicuspids only one 
 root, even when there are two quite distinct and divergent ones. 
 Generally it is only necessary to take one exposure of these teeth if a 
 slightly mesial direction is chosen (Fig. 543). Should the tooth, how- 
 ever, be twisted so as to face buccally to a slight extent with its distal 
 surface it will be found that a disto-buccal view gives a better picture. 
 
 Fig. 536 
 
 Fig. 537 
 
 Fig. 538 
 
 Fig. 539 
 
 In root-canal work the operator may want to know which is the buccal 
 and which the lingual root. This can be easily determined. If the 
 picture is taken from a mesial aspect the buccal root is projected 
 distally, that is, nearer the second bicuspid, the lingual root mesially, 
 or next to the cuspid. The same holds true for the root canals in both 
 teeth (Fig. 544). In the lower jaw the technic is less complicated. 
 If there be two canals In a molar root they can be identified by means 
 of a slightly mesio-buccal or disto-buccal direction of the rays exactly 
 as has been explained for the upper bicuspids. 
 
682 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 Fig. 540 
 
 Direction for 
 Mesio-Buccal root 
 
 Direction for 
 Disto-Buccal root 
 
 Fig. 541 
 
 \ Buccal root 
 \Lingual root 
 
 Fig. 542 
 
 Fig. 543 
 
 aK^s:i?aH«&"'.'S33»:!»r 
 
 Fig. 544 
 
METHOD OF TAKING ROENTGEN PICTURES OF TEETH 683 
 
 Length of Exposure. — ^Various factors govern the time of exposure. 
 The greatest variations are due to the type and output of the machine 
 and the make of tube. It is therefore a matter which will have to be 
 ascertained in the individual case and may be determined after a 
 little experimentation. It will be found, however, that after a while 
 a slight increase in time is needed unless the output of the machine 
 can be increased to overcome a decrease of the efficiency, which comes 
 with the use of the induction coil and the aging of the tube. 
 
 The milliamperage of the current passed into the tube is, perhaps, 
 the most important factor. The time of exposure can be decreased 
 in proportion to the increase of the milliamperage. If the milliamper- 
 age is doubled the time of exposure is cut down one-half. 
 
 A variation in the distance of the target from the plate also changes 
 the length of the exposure, the change being in proportion to the 
 square of the distance. If, for example, the target distance should 
 be doubled it would be necessary to make the exposure four times as 
 long. If with a known exposure time of T seconds and a target dis- 
 tance of Da inches a new target distance (Db) be chosen, the new 
 exposure time (X) can be calculated by the following equation: 
 
 iW 
 
 Variations in the object to be roentgenographed have to be con- 
 sidered both in regard to changing the penetrating quality of the rays 
 as well as the length of the exposure. Thick and dense bone needs 
 greater penetration, a higher vacuum in the tube and a longer exposure. 
 It skpuld be remembered that bone varies not only in different parts 
 of the jaws but also according to the build of the bony frame of the 
 individual. In old people, again, we find a higher degree of calcifica- 
 tion than in a child. 
 
 Further factors are the sensitiveness of the roentgen film or plate. 
 The different makes vary and there are both fast and slow films on 
 the market. The latter usually give better results because slight 
 mistakes will not result in poor pictures. The fast films permit only 
 slight variations. A slow film, if overexposed, can be saved in the 
 developing process. The length of exposure can also be greatly 
 decreased by the use of intensifying screens. These are most useful 
 for extra-oral exposures, especially for sinus pictures. The new 
 Eastman double-coated films, which are used for head work in the 
 sizes 6x8 or 8 x 10 give splendid pictures when used with double 
 screens in special screen holders or cassettes, the purpose of which 
 is to bring the film into close contact with the screens. The action 
 
684 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 of the intensifying screen depends upon a fluorescence, which is pro- 
 duced on the surface of the screen when the roentgen rays pass through. 
 The actinic hght, which the screens emit, will continue to act on the 
 emulsion even after the exposure is completed. With double screens 
 the length of exposure can be decreased to at least one-fourth of 
 the normal time. 
 
 The effect of the developing must also be considered sometimes 
 when viewing a thin picture. It may appear to have been under- 
 exposed when the real fault lay in the development. If the developer 
 is too weak or too cold the picture will not be as good as could be 
 expected. 
 
 Table Giving Time of Exposure. 
 
 Object. 
 
 Target 
 distance 
 in inches. 
 
 Resistance 
 of tube back 
 up in inches. 
 
 Milliam- 
 peres. 
 
 Time of 
 expos- 
 ure. 
 
 Milliam- 
 
 peres, 
 seconds. 
 
 For 
 
 change 
 
 in target 
 
 distance 
 
 Db 
 
 CooUdge tubes 
 figure niilHam- 
 pere seconds. 
 
 Letters used in 
 equation 
 
 Da 
 
 V 
 
 A 
 
 T 
 
 AxT 
 
 AxT 
 
 
 
 
 
 
 
 
 150 
 
 
 Teeth intra-oral . 
 
 15 
 
 4 
 
 30 
 
 5 
 
 150 
 
 210 
 
 1 AxT 
 
 Jaws intra-oral . 
 
 18 
 
 4 
 
 35 
 
 6 
 
 210 
 
 260 
 
 |AxT 
 
 Jaws extra-oral . 
 
 20 
 
 4 
 
 35 
 
 7 
 
 260 
 
 P' 
 
 |AxT 
 
 Sinuses, anterior- 
 posterior 
 
 22 
 
 4i 
 
 40 
 
 8 
 
 320 
 
 320 
 /22\ 2 
 
 i AxT 
 
 Development of Roentgen Films. — The films are developed in a dark- 
 room or developing cabinet. Three porcelain bowls, approximately 
 five inches wide, are used to contain the developer, the iixing-bath 
 and the rinsing water. Special clips (Fig. 545) are designed to use 
 with such bowls. They facilitate the management of the films and 
 make it possible to do the developing without immersing the fingers 
 in staining chemicals. A clip is attached to each film, and care 
 should be taken to wash the clips well after use. The developing 
 fluid is best prepared from powders, which are manufactured by 
 concerns like the Eastman Company. After using it should be 
 poured back into a bottle or covered over to prevent free access of air 
 which causes oxidation. It is a good plan to add a certain amount 
 
METHOD OF TAKING ROENTGEN PICTURES OF TEETH 685 
 
 of new developer when it is used again, as the chemicals become less 
 active with age and use. The fixing fluid can be used for a con- 
 siderable length of time and may safely be kept in an open bowl. 
 The films must be well rinsed after they are taken from the developer 
 before being transferred to the fixing-bath. The temperature of the 
 developing fluid affects the picture considerably, and in winter it is 
 often necessary to heat it slightly. The proper temperature is about 
 65° F. In hot weather the films are often spoiled because the emul- 
 sion becomes too warm and melts or causes blisters to appear on the 
 surface of the film or frills on the margin. It is often advisable to use 
 ice water for the washing and to cool the solution. The author prefers 
 to add a teaspoonful of alum to the bowl of fixative, as well as into the 
 washing water. The astringent action preserves the film. 
 
 Fig. 545 
 
 Roentgen films are developed in the same manner as photographic 
 negatives, and one who has some experience in photography will be 
 able to save a good many pictures which have not been quite properly 
 exposed. The inexperienced operator will probably at first get most 
 satisfactory results if he times the developing. With the Eastman 
 developer for dental films the time is five minutes, after which the 
 film is rinsed in clear water and placed in the fixing-bath until it is 
 entirely transparent when held to the light. A film may be left in 
 the fixing-bath any length of time without spoiling it. After being 
 fixed the film should be washed in running water for about fifteen 
 
686 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 minutes or in standing water for an hour, during which time the 
 water should be changed several times. It should be finally hung 
 up by the hook of the clip until dry, when it is finished. The drying 
 process may be hastened by putting the film into alcohol for a few 
 seconds after washing it. 
 
 There are various opinions as to the appearance of a perfect roentgen 
 negative. Some roentgenologists like them very dark, so as to neces- 
 sitate holding in front of a strong light, while others prefer light, but 
 contrasting pictures, which may be examined in ordinary daylight, as, 
 for example, in front of a window. The author prefers the latter 
 type, which are made with a fairly high penetration, but backed up 
 by enough milliampere seconds to give, if properly developed, an 
 entirely black picture of the radioparent parts and a very translucent 
 picture of the parts which are radiopaque. 
 
 Recognition of the Cause of Poor Results. — It is generally difficult 
 for the student to determine the cause of a poor picture and to find 
 the reason for his failure to get as good results as someone else. Quite 
 frequently he blames the machine, when the fault is clearly a matter 
 of technic. When trying to trace the cause of the failure it is best 
 to think the matter over carefully and to consider first the roentgen 
 machine. It can be easily and quickly tested by attaching it to a 
 tube with a certain back-up and taking the reading of the milliampere- 
 meter. If the reading is less than usual it is a sign that the output 
 of the machine has been decreased. This may be due to a drop in the 
 incoming street current or improper functioning of the interrupter 
 or induction coil, of the transformer or commutator, or other parts, 
 according to the type of machine. 
 
 The tube may not be working properly. Gas tubes often become 
 freakish, flitter and become soft during the exposure. If the tube is 
 too high the picture will not show enough contrast and will appear 
 flat (Fig. 546) . If the tube is too low in vacuum there is not enough 
 penetration of the hard tissue and the resulting picture will be thin 
 (Fig. 547). In Fig. 548 the patient moved and the picture therefore 
 is not very clear. 
 
 The result of overexposing or underexposing can often be corrected 
 by proper development. Such errors are due to exposing the film 
 too long or for too short a time or to the use of too large or too small 
 a milliamperage. If too many milliampere seconds are employed 
 and the picture is developed the normal length of time it becomes 
 very black and may be so dense as to make it impossible to read it, 
 even by a very strong artificial light (Fig. 549). An overexposed 
 picture develops almost instantly and can only be saved by imme- 
 diately diluting the developer and removing the film fis soon ^s it is 
 
METHOD OF TAKING ROENTGEN PICTURES OF TEETH 687 
 
 
 Fig. 546 
 
 Fig. 547 
 
 Fig. 548 
 
 LJ 
 
 Fig. 549 
 
 Fig. 550 
 
 Fig. 551 
 
 \ ^ 
 
 Fig. 552 
 
 Fig. 553 
 
 Fig. 554 
 
 Fig. 555 
 
 Fig. 556 
 
 Fig. 557 
 
688 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 finished. Overexposed pictures may also be improved by the use 
 of a reducing fluid, such as can be bought from any photographic 
 supply house. If too few milliampere seconds are used the picture 
 develops very slowly, the radioparent parts fail to become black 
 enough and if the development is forced, that is, if it is continued much 
 longer than usual, the negative becomes fogged and, after being 
 fixed, often has a yellowish color (Fig. 551). Fig. 550 shows a normal 
 roentgenogram for comparison. 
 
 The effects of development have already been described. When 
 the developer is too cold the result is a very thin picture, as shown in 
 Fig. 552. A similar condition may be produced by a developer which 
 is too old or by underdevelopment of the negative (Fig. 553). An 
 overdeveloped picture looks about the same as an overexposed one 
 (Fig. 554). 
 
 Other poor results may be produced by movement of the patient, 
 vibrating of the tube or slipping of the film, which cause the picture 
 to become indistinct, losing in sharpness. If the supply of films is 
 not properly stored they may become fogged (Fig. 555) . Films should 
 be kept in a lead box so as to protect them from the rays when expo- 
 sures are being made. Daylight will not affect them so long as the 
 packing is intact, but if the packing becomes torn, or if light is allowed 
 to strike the film through carelessness before or during the develop- 
 ment the picture may be partly defective, fogged or entirely spoiled 
 (Fig. 556) . Hot weather often causes the emulsion on the film to melt 
 as seen in Fig. 557. 
 
 INTERPRETING ROENTGEN PICTURES. 
 
 To interpret a roentgen picture correc^"ly is the most important 
 work of the roentgenologist. It is absolutely necessary that he 
 should have careful training and special knowledge in the anatomy, 
 histology and pathology of the parts he is to examine. If he is a 
 dental roentgenologist he should also be familiar at least with the 
 various dental procedures and problems of dentistry or he will not 
 be able to cooperate with the general practitioner sufficiently to give 
 him the greatest possible benefit from his services. The author 
 cannot forego this opportunity to lament the fact that, on account 
 of inefficient laws, roentgen laboratories have been established in 
 most of the larger cities by laymen who not only make roentgen 
 pictures but also supply most elaborate reports. Through advertis- 
 ing they attract patients and, worse still, otherwise reputable dentists 
 who refer their own patients to them. Such practitioners lower the 
 
INTERPRETING ROENTGEN PICTURES 689 
 
 standard of this important specialty and of the dental profession in 
 general, to say nothing of exposing their patients to false advice, based 
 upon the opinion of an ignorant person. 
 
 The value of roentgen diagnosis depends upon correct interpretation 
 of the picture, and such interpretation can only be made from a good 
 roentgenogram. When reading a picture, however, one should not 
 forget the history of the case and the clinical findings. The roentgen- 
 ogram does not picture disease. It only records changes in the radia- 
 bility of the tissues, which have been brought about by pathologic 
 processes as well as surgical and medicinal treatment. Such changes 
 in the outlines;, or radiability, are correct and accurate pictures of 
 grosser structural abnormalities; finer pathologic conditions, such 
 as those seen under microscope, cannot be recognized. A roentgen 
 diagnosis is, therefore, made by drawing deductions from the records 
 made by the roentgen examination and the roentgenologist must 
 become proficient in associating roentgen signs with corresponding 
 diseased conditions. In a roentgenogram of a tooth, for example, 
 the picture of the pulp is the same, whether diseased or normal; but 
 if a dark area, indicating decay, is shown in the crown of the tooth, 
 and if this area comes close to the pulp, one may suspect pulp disease. 
 If there be symptoms, or clinical evidence of pulp disease, the diag- 
 nosis is fairly certain. If, in addition to the above, the picture shows 
 changes around the apex of the tooth which are associated with infec- 
 tion the roentgenologist can, from this evidence alone, without clinical 
 indications, draw conclusions which lead to the diagnosis of pulp 
 disease. 
 
 With advances in technic and improvement in the quality of the 
 pictures it is possible to demonstrate finer changes, while experience, 
 careful observation and systematic study of a large number of similar 
 cases, as well as comparison of roentgen diagnosis with post-operative 
 findings, or results of pathologic examinations, wall make it possible 
 to carry the roentgen diagnosis to a finer and finer point. As an 
 example, take the difi^erentiation between granulating ostitis and a 
 radicular cyst. In both cases a large dark area may be shown in 
 the film, due to the increased radiability of the area w^here loss of bone 
 has occurred. Granulating ostitis is distinguished from the cyst by the 
 appearance of the outline of the diseased part in the picture. An 
 irregular margin and gradual change from the diseased to the healthy 
 part indicates ostitis, while a clear demarcation of definite outline 
 indicates that the bone itself has not become infected, but th,at pres- 
 sure absorption has occurred, the bone cavity having been reinforced 
 by a dense layer of normal cortical bone. 
 
 A roentgen picture is a record upon a photographic plate or film 
 44 
 
690 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 of the radiability of tissues through which the rays are passed. Soft 
 tissue is very radiolucent and, if not too thick, transmits the rays 
 almost as well as air. Bone containing a large percentage of calcium 
 salts is very much less radiolucent and enamel, containing almost no 
 organic matter, is the most opaque tissue in the body. Gold, silver, 
 lead and other metals are almost entirely radiopaque. Figs. 558, 559 
 and 560 illustrate changes in radiability. Fig. 558 shows the normal 
 molars in the lower jaw. A cavity drilled into the buccal surface of 
 the second molar increases the radiability and, since-the obstruction to 
 the passage of the rays is decreased, a dark shadow, corresponding to 
 the size and outline of the hole, appears on the film (Fig. 559) . Metal 
 placed into this cavity renders the area impervious to the roentgen 
 rays and a light area is shown in the picture (Fig. 560). 
 
 When examining a roentgenogram look first for any departure 
 from the normal, such as irregularity in size or outline of the object 
 or any change in its normal radiability. It is of great advantage to 
 compare the part under observation with the corresponding part on 
 the other side of the individual, especially when there is any doubt- 
 when the appearance of the condition in the picture is not pronounced 
 and not readily recognizable. The age of the patient should also be 
 considered. An unerupted tooth, for example, is a normal condition 
 in a child, while in the adult it deserves serious consideration. 
 
 Misconceptions may arise from distortion of the angle at which 
 the picture is taken, from faulty technic in the development, lack 
 of sufficient knowledge to recognize pictures of anatomic structures, 
 such as the mental foramen, the incisive foramen and the maxillary 
 sinuses, or shadows of interposing parts, such as the coronoid process 
 of the ramus in the upper third molar region or the nose and nostrils 
 in front of the upper jaw. The picture of the mental foramen may 
 be projected so that it comes exactly over the apex of a bicuspid root, 
 appearing the same as would an apical abscess. The mandibular 
 canal, however, may usually be traced to it, which helps in the identi- 
 fication. The incisive foramen will often give a picture superimposed 
 over that of the apex of the central incisor, especially if the exposure is 
 made from a slightly lateral angle. A new film, taken from a difi^erent 
 viewpoint, will usually clear up all doubt. Beginners often mistake 
 parts of the maxillary sinuses for extensive diseased conditions. 
 Occasionally a case is referred to the author for extraction of an 
 upper third molar tooth root, which is only the shadow of part of 
 the ramus, taken from a fairly vertical direction and an extremely 
 (iistal point of view, 
 
INTERPRETING ROENTGEN PICTURES 
 
 691 
 
 Fig. 558 
 
 Fig. 559 
 
 Fig. 560 
 
692 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 GENERAL ROENTGEN EXAMINATION OF THE TEETH. 
 
 The method of examination of the mouth, as practiced by the 
 average dentist in the past, is thoroughly inadequate. As a rule, 
 little care is taken to consider the mouth as a whole, and even in 
 localized conditions there is a tendency to try various methods of 
 treatment before ascertaining the cause and the exact nature of the 
 trouble. In a general way we may say that we have two kinds of 
 patients to examine, those who come with a definite complaint and 
 those who want a general examination of the mouth. It is with the 
 first class that most of our mistakes are made. Take, for instance 
 the patient who wants to have one particular tooth extracted because 
 he thinks it is the cause of some systemic disturbance; the folly of 
 extracting this one tooth, even if it were an infectious focus, without 
 thoroughly investigating the condition of the rest of the teeth is 
 obvious. It is extremely unwise to jump at conclusions. The most 
 proficient diagnosticians seldom depart from a systemic plan of exami- 
 nation, and it is always well to adopt a certain routine and follow it" 
 in every case. 
 
 It is advisable to inquire into the patient's general health, for it must 
 be borne in mind that the teeth are not isolated organs but are in 
 immediate relation to other important structures and closely asso- 
 ciated with the rest of the body. The mouth may be the seat of 
 secondary lesions of general diseases, such as the eruptive fevers, 
 tuberculosis and syphilis, and, on the other hand, infectious lesions 
 in the mouth may be the primary or contributory cause of somatic 
 disturbances. If there be some special local condition of which the 
 patient complains an exact history should be taken. The mouth 
 should then be inspected, the condition of the teeth being noted first 
 to see whether they are healthy or neglected or whether they show 
 signs of dental work, either good or poor. The lips, cheeks, palate and 
 gums should be examined next. Inflammatory changes, swellings and 
 fistulse are also noted. 
 
 Unless it is evident that the teeth are perfectly healthy, that there 
 are no large fillings, crowns or bridges, a roentgen examination is 
 indicated. A patient seen for the first time, or an old patient whose 
 teeth have never been roentgenographed, should have a routine 
 examination — that is, pictures of all the teeth (Figs. 561 to 577). 
 If this is systematically carried out one will often be surprised to 
 find definite diseased conditions on teeth which would have passed 
 by in a superficial examination. Indications of decay under fillings 
 or of cavities concealed under the gums are frequently discernible; 
 unerupted teeth may be discovered and the conditions of root canal 
 
GENERAL ROENTGEN EXAMINATION OF TEETH 693 
 
 Fig. 561 
 
 Fig. 562 
 
 Fig. 563 
 
 Fig. 564 
 
 Fig. 565 
 
 Fig. 566 
 
 Fig. 568 
 
 Fig. 569 
 
 Fig. 570 
 
604 ROENTGEN DIAGNOSIS iN OPERATIVE DENTISTRY 
 
 fillings and status of devitali/.ed teeth are disclosed. Pus pockets due 
 to faulty contact points, overhanging fillings and other mechanical 
 irritations become clearly visible, together with their cause, and in 
 
GENERAL ROENTGEN EXAMINATION OF TEETH 
 
 (m 
 
 pyorrhea! conditions, valuable information can be gathered as to the 
 amount of bone destruction and deposit of serumal calculus in the 
 pockets. The roentgen examination is of further value in leading to 
 the discovery of other conditions which cannot be definitely demon- 
 strated in the picture, but the appearance of which arouses suspicion 
 and indicates the necessity of further clinical study. 
 
 The pictures, after completion, should be mounted on a film mount 
 designed to hold the entire set, so that the views of the whole mouth 
 can be seen at once and carefully studied before the patient comes 
 
 Dentist 
 ,Phj 
 (File 
 
 Original^ for , pu„„i-:„n 
 Copy 1 the i i-^'JP'"^*^ 
 
 RIGHT ^ 
 
 FLOOR 0P\ 
 ANTRUM 
 
 LEFT 
 
 FLOOR OP 
 
 Peiiapical-Alveolar abscess 9. 
 
 Canal not filled 10. 
 
 Absorption of apex ii. 
 
 Apex not filled 12. 
 
 Apex filling projects 13. 
 
 Wire-Broach in canal 14. 
 
 Perforation of canal 15. 
 
 Irritation, shell crown 16. 
 
 Irritation, filling 
 Pericementitis (Lame tooth) 
 Alveolar Absorption — pyorrhea 
 Gingivitis 
 Cavity 
 
 Unextracted root 
 Fracture of root 
 Unerupted tooth 
 
 17. Supernumerary tooth 25. 
 
 18. Impacted tooth 
 
 19. Fracture of jaw 
 
 20. Process fractured 
 
 21. Cementoma 
 
 22. Pulp stone 
 
 23. Bone "whorl" 
 
 24. Bone cyst 
 
 Bone tumor 
 Root in antrum 
 Antral empyema 
 Apex amputated 
 Test vitality 
 Amputate root 
 Extraction indicated 
 Contact point. 
 
 (Dr. Bryon C. Darling Dental Chart.) 
 
 Copyrighted, 1918. 
 Fig. 578 
 
 The Peck Press, New York. 
 
 in again. Records should then be made on an examination chart. 
 The trouble with the majority of dental examination charts is that 
 they are designed to indicate only the condition of the crowns of the 
 teeth. Darling's dental chart, seen in Fig. 578, may be used by 
 the roentgenologist. For the general practitioner of dentistry this 
 chart does not give enough room for the recording of cavities and 
 fillings in all the tooth surfaces. The Potter chart (Fig. 579), which 
 is more elaborate, makes it possible to include a record of all dental 
 conditions. This chart has been carefully worked out by Professor 
 
696 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
GENERAL ROENTGEN EXAMINATION OF TEETH 
 
 mi 
 
698 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 William H. Potter from originals of historical interest by Carabelli. 
 The back of the chart is arranged for bookkeeping. The films should 
 be kept mounted on file until the patient is finally dismissed, and 
 at each visit the pictures should be before the operator. After the 
 work is completed the film may be dismounted and filed in envelopes 
 with the patient's record. 
 
 ROENTGEN EXAMINATION OF THE JAWS IN SOMATIC 
 
 DISEASE. 
 
 It is not within the scope of this contribution to discuss the relation 
 of oral infections to somatic disease. There is no reason why dental 
 diseases are not as likely to be the cause of focal infection as diseased 
 tonsils, infected sinuses or gastro-intestinal disturbances. With the 
 roentgen method it is possible to discover infections in the jaws which 
 cause no symptoms and cannot be diagnosed by any other means, but 
 whether such infectious lesions in the mouth are the original foci, or 
 one of several from which bacteria have migrated to other organs; 
 whether it is only absorption of toxins from these foci which cause 
 the secondary disease, or whether the dental infections and the sys- 
 temic conditions are simply coexistent and not directly related to each 
 other, are questions which must be considered separately for every 
 case. Also positive statements cannot be made with absolute certainty 
 as to thie probable benefit from removing the focus, since the secondary 
 lesion or disease may be of such long standing that the removal of 
 the original focus has but little effect, the secondary lesion not having 
 received proper attention, or the tissue changes may be so extensive 
 that restoration to the normal can no longer be expected. The best 
 results are obtained in cases of short duration and especially in those 
 in which the secondary disease is due to a toxemia rather than to 
 bacterial migration. After finding oral lesions in a patient who com- 
 plains of symptoms caused by diseases conceded to be due to focal 
 infection the patient should first be carefully examined by an internist. 
 It is for him to decide the nature of a given case and whether focal 
 absorption of toxins or bacteria may be an etiological factor. 
 
 Another aspect of this problem is the question as to whether it is 
 perfectly safe for an otherwise healthy patient to retain teeth which 
 on account of their chronic character, give no local disturbance, but 
 which show infectious processes at the ends of the roots when roentgen- 
 ographed. While there is little doubt in most cases as to what should 
 be done with badly infected teeth, there are, nevertheless, cases in 
 which we should like to recommend and try more conservative methods 
 if we could be sure that no absorption was taking place. In cases of 
 
ROENTGEN EXAMINATION OF JAWS IN SOMATIC DISEASE 699 
 
 long standing, in which apical necrosis and absorption are discovered 
 in the roentgen picture, indicating clearly that Nature wants to elimi- 
 nate such an obnoxious foreign body, extraction is indicated from a 
 purely dental point of view. No one w^ho has studied the tooth and 
 bone pathology of old pus-soaked teeth, or who has experienced the 
 odor of one which has been removed, would ever hesitate to recom- 
 mend extraction simply for the sake of cleanliness. But in cases 
 of short standing, especially in younger patients, treatment and 
 retention of the tooth would seem advisable if the roentgenographic 
 indications are favorable to root-canal work. Two tests have recently 
 been used by the author, with the kind cooperation of Dr. Cotton, 
 of the New Jersey State Hospital, and Dr. Charles Lawrence, of 
 Boston, to demonstrate whether or not products of bacterial activity 
 have been absorbed. Dr. Cotton^ recommends the complement- 
 fixation test for streptococci for this purpose, with which he has 
 made extensive experiments. The skin test, as used for proteid 
 poisoning, is more readily available, and if it continues to prove 
 reliable when verified by the complement-fixation test and bacterio- 
 logical study of the tooth roots it will be of the greatest value. 
 
 The most common oral diseases from which absorption takes place 
 are alveolar abscesses, pus pockets, pyorrheal infections, infections 
 around impacted teeth, as well as more extensive bone infections in 
 the jaws, such as ostitis, osteomyelitis and infected cysts. A sys- 
 tematic roentgen examination of the teeth and jaws is necessary in all 
 these conditions, and with few exceptions a complete set of dental 
 films should be taken. 
 
 The case of Mr. G. is a good illustration: he complained of pain 
 in his back and shoulders, which incapacitated him for w^ork, as he 
 was a chauffeur. Roentgen examination of the shoulders and spine 
 revealed no bony changes, which led to the conclusion that the disease 
 was of recent standing. He had a careful physical examination and 
 no cause was found to which his trouble might have been attributed. 
 A complement-fixation test of the blood showed a 3+ reaction to 
 hemolytic streptococci, 3+ to Streptococci viridantis and 3+ to the 
 colon bacillus. The skin test reacted positively to hemolytic strepto- 
 cocci. Streptococci viridantis and pneumococci. No skin test was made 
 for the colon bacillus. Roentgen pictures were taken of all the teeth, 
 which showed many abscesses, as seen in Figs. 580 to 589. The left 
 upper first and second molars, the left lower first and second molars, 
 the right upper central and lateral incisors and the first molar and 
 the right lower first and second molars were extracted. Pure cultures 
 
 1 Cotton, Henry A. : The Relation of Oral Infection to Mental Diseases, The Journal 
 of Dental Research, vol. i, No. 3, p. 269. 
 
700 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 Fig. 580 
 
 Fig. 581 
 
 Fig. 582 
 
 Fig. 583 
 
 Fig. 584 
 
 Fig. 585 
 
 e-i-} 
 
 i 4 
 
 Fig. 586 
 
 Fig. 587 
 
 I 
 
 L'J 
 
 Fig. 588 
 
 Fig. 589 
 
ROENTGEN EXAMINATION OF THE TEETH 
 
 701 
 
 of Streptococci viridantis and hemolytic streptococci were obtained. 
 The patient improved very rapidly, so that he was able to go to work 
 very soon, and is now driving a truck. 
 
 ROENTGEN EXAMINATION OF THE TEETH IN DISEASES OF THE 
 MAXILLARY SINUSES. 
 
 Maxillary sinusitis in its various forms is, according to Brophy, 
 in about 75 per cent, of the cases due to diseases of the teeth. Acute 
 infections may be caused by careless instrumentation (Fig. 591), 
 
 Fig. 590 
 
 Fig. 591 
 
 Fig. 592 
 
 Fig. 593 
 
 or pushing of an infected root into the antrum. Chronic abscesses 
 on the upper teeth very frequently cause chronic infection of the antra, 
 with polypoid degeneration of the mucous membrane. This condi- 
 tion often develops without the patient's knowledge and is discov- 
 ered only in routine examination. If large abscesses are seen in the 
 roentgen pictures of the upper molars and bicuspids, as shown in Figs. 
 590 to 592, sinus disease should always be considered as a possibility. 
 Roentgen pictures of the head should be taken for investigation of the 
 sinuses (Figs. 594 and 595), and, on the other hand, in cases of sinus 
 symptoms or sinus disease the teeth should not be neglected and their 
 
702 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 condition must be investigated roentgenographically. Maxillary sinu- 
 sitis caused by a tooth and cured by its extraction is illustrated in the 
 following case : The tooth in question, a right upper bicuspid, had been 
 devitalized for several years on account of an exposure made when pre- 
 paring the tooth for a cohesive gold filling. About one year ago a 
 roentgenogram was taken, which showed a very slight bone infection. 
 The root canal was treated experimentally by various modern methods 
 and then filled under strict asepsis. Later a bridge was attached to the 
 
 Fig. 594 
 
 tooth, which became slightly tender, and one morning three months 
 later a fulness and throbbing sensation was felt in the region of the 
 right maxillary sinus when stepping hard arid a small amount of 
 gelatinous substance was discharged through the right nostril. An 
 anterior-posterior roentgen picture taken the same day (Fig. 594) 
 showed the right sinus to be dense, and on transillumination it was 
 entirely dark. The tooth shown in Fig. 593 was extracted at once and 
 a probe passed into the alveolar socket, which showed, however, that 
 
ROENTGEN EXAMINATION OF THE TEETH 
 
 703 
 
 there was no opening through the floor of the antrum. No further 
 treatment was resorted to; the symtoms disappeared and, after seven 
 weeks, the sinus was clear on transillumination and in the roentgen 
 picture (Fig. 595). 
 
 Fig. 595 
 
 ROENTGEN EXAMINATION OF THE TEETH IN TRIFACIAL 
 NEURALGIA. 
 
 The extensive area of distribution of the trifacial nerve and its 
 frequent communications with other cranial nerves and the sympathetic 
 system explains the clinical manifestations that pa;in and irritation 
 originating from some dental or oral cause may be referred to very 
 distant parts of the face and head, including the ear (otalgia dentalis), 
 the eye, the nose and accessory sinuses. Such pain may be continu- 
 ous, intermittent or periodic; it may be intense, sharp, throbbing or 
 dull, and it may be a sensation of obscure, indefinable pressure. It 
 sometimes results in more serious nervous disorders, such as insomnia, 
 melancholy and epilepsy. 
 
704 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 The suffering that goes with these conditions is often intense, and 
 if of sufficient duration wears the patient out. The cause may be 
 difficult to ascertain and the condition calls for a careful study with 
 temperature and electrical tests as well as painstaking roentgen 
 examination both of the entire side of the affected jaws and the teeth. 
 Frequent etiologic factors are impacted and unerupted teeth, obscure 
 pericemental infections and affections of the dental pulp, such as 
 irritation from improperly fitting bridges, poor fillings, pulp nodules 
 (Fig. 596) and infection from decay starting either underneath the 
 gum or continuing, on account of insufficient sterilization, after the 
 tooth has been filled. An illustration is to be found in the follow- 
 
 FiG. 596 
 
 Fig. 597 
 
 Fig. 598 
 
 ing case report. Mrs. V. G. L. had attacks of neuralgia on the left 
 side of the face at intervals. For three days she had been in severe 
 pain, which was especially located in the ear and zygomatic region. 
 Roentgen examination (Fig. 597) showed a large radiolucent area 
 also a radiolucent area indicating infection at the apex of the tooth. 
 From these findings we conclude that the pulp is diseased. The 
 operative findings revealed a pulp which was necrotic. In another 
 case the cause was found in the upper jaw. Miss R. had had periodic 
 headaches in the back of the head for several years. They were 
 quite severe and always on the right side. Sometimes the whole half 
 of the head would ache. Roentgen examination (Fig. 598) showed 
 
SPECIAL ROENTGEN STUDY OF DENTAL DLSEASES 705 
 
 infection of the right upper first and second molars, with formation of 
 a small cyst, also an unerupted, impacted third molar. The pressure 
 exerted by this tooth caused the well-illustrated tipping of the second 
 molar. A frontal plate of the sinuses was negative. Extraction of the 
 three molars was decided upon, and during the operation the antrum 
 was opened and, after u-rigation, closed with sutures. The treatment 
 relieved the symptoms. 
 
 SPECIAL ROENTGEN STUDY OF DENTAL DISEASES. 
 
 It has already been stated that a roentgenogram is not a picture of 
 disease but a record of the changes in the radiability of the tissues, 
 brought about by pathologic processes or surgical interference. In 
 interpreting a roentgen picture the history and clinical manifesta- 
 tions should also be considered, as they often will be of great help. 
 One of the best means of learning to read roentgen pictures is by 
 carefully studying typical illustrations in a text-book,^ which are 
 reproduced with the full history, symptoms and clinical signs, patho- 
 logic report and findings during and after the operation or treatment. 
 The purpose of this chapter, therefore, is to show the reader such 
 typical cases, giving, if possible, photographs of specimens of similar 
 pathologic conditions to illustrate how the disease affects the tissue 
 and its radiability. 
 
 Although this contribution is to be restricted to the roentgenology 
 of conditions which concern operative dentistry the author intends to 
 include such lesions and diseases as are closely associated with the 
 teeth. The operator should be familiar with their pathology and 
 diagnosis, so as to be able to differentiate them from simpler affections 
 of the teeth, recognizing them early and advise the patient in time. 
 For example, large cysts are frequently treated with root-canal medi- 
 cation and an extensive osteomyelitis, as pyorrhea. 
 
 Abnormal Dentition. 
 
 Irregular Eruption. — If temporary teeth decay early and become 
 abscessed, or if they are retained too long, it is advisable to 
 investigate the progress of development and the size of the per- 
 manent teeth by means of roentgen pictures. The permanent teeth 
 may be prevented from erupting on account of impaction of the 
 temporary teeth. In the case illustrated by Fig. 599, a child, aged 
 twelve years, lacked the second bicuspid in the lower jaw. No tem- 
 porary second molar could be seen, but part of the tooth was visible 
 
 1 Thoma, K. H. : Oral Roentgenology, Boston, M. C. Cherry. 
 45 
 
706 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 through a perforation in the gum, which had the appearance of show- 
 ing a broken-down root. Roentgen examination showed the entire 
 crown of the second temporary molar impacted between the first 
 molar and the first bicuspid. Its roots had been absorbed, but its 
 retention prevented normal eruption of the second bicuspid. A 
 similar condition is shown in another case (Fig. 600). A girl, aged 
 twelve years, had a temporary molar which was entirely under the 
 
 Fig. 599 
 
 Fig. 600 
 
 gum, impacted between the two permanent teeth. Its roots showed 
 signs of resorption, but the second bicuspid was mal-shaped and 
 showed only rudimentary development. 
 
 Misplacement of a tooth germ is frequently the cause of permanent 
 teeth not erupting. In the case shown in Fig. 601 a space was held 
 open for the permanent cuspid for a long time until a roentgenogram 
 showed it to be entirely out of position. 
 
 Fig. 601 
 
 Fig. 602 
 
 Sometimes, however, the permanent teeth are entirely missing. A 
 large roentgen picture should always be taken to make sure they 
 have not migrated to a position outside the realm of the small dental 
 film. In the case shown in Fig. 602, a child, aged fourteen years, the 
 second temporary molar was retained, while all the other bicuspids 
 had erupted. The roentgen picture showed slight resorption at the 
 root apices and absence of the permanent tooth which should take 
 its place, 
 
SPECIAL ROENTGEN STUDY OF DENTAL DISEASES 707 
 
 In congenital absence of temporary teeth the permanent ones 
 may be missing also. In the case of a boy, aged twelve years (Fig. 
 603), the temporary lateral incisor had never come through. By 
 means of roentgen diagnosis it was found that not only the temporary 
 but also the permanent lateral was entirely missing. 
 
 If the temporary tooth is present and is retained it is important to 
 know whether its roots have become absorbed or whether they show 
 a normal condition. The author has seen healthy temporary teeth 
 with well-shaped roots and vital pulps in patients up to the age of 
 forty. 
 
 Fig. 603 
 
 Artificial Eruption. — Many times, especially in younger people, un- 
 erupted teeth can, in favorable cases, be erupted artificially. iVfter 
 locating the exact position of an unerupted tooth by the roentgen 
 methods the gum is incised and the bone overlying the tooth removed, 
 so that part of the enamel is exposed. The tissue is then cauterized 
 and packed w^ith rubber tissue. After forty-eight hours the packing 
 can be removed and, if proper care is taken, without causing any 
 bleeding. A small loop of platinum wire is then cemented into a 
 hole drilled into the tooth. To this may be attached an extension 
 from the orthodontia arch wire, by means of which gradual force is 
 applied until the tooth is moved to its normal position. To illustrate 
 what may be done the following case of Dr. iVlfred Rogers' serves as 
 an illustration. Fig. 604 shows the condition two days after the 
 author had operated on an unerupted cuspid, the appliances having 
 just been attached. After nine months the tooth was almost in its 
 
708 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 Fig. 604 
 
 Fig. 605 
 
 Fig. 
 
 Fig. 607 
 
 Fig. 
 
SPECIAL ROENTGEN STUDY OF DENTAL DhSEASES 709 
 
 proper position, except that a certain amount of rotating was still 
 necessary. The condition at this time is shown in Fig. ()05. Not 
 always, however, can such successful results be obtained. In the 
 case illustrated by Fig. 606, which shows the condition before treat- 
 ment and Fig. 607, which shows the tooth after attachment of the 
 appliances, constant force was applied for ten months with apparently 
 no result whatever, as seen in Fig. 608. The cuspid is still in its old 
 position, probably firmly impacted over the resorbed surface of the 
 lateral. Examine also the apices of the roots of the other incisors. 
 They are all vital, the condition of the roots being due to incomplete 
 formation. 
 
 Fig. 609 
 
 Fig. 610 
 
 Replacement by Bridge-work. — If bridge-work is contemplated to 
 replace a missing tooth, the history of which is not entirely known, 
 it is better to ascertain by means of a roentgen picture whether it is 
 embedded in the jaw. This precaution may save the patient con- 
 siderable trouble. In the case of an adult patient a bridge was con- 
 structed by her dentist to replace a cuspid which was missing. Some- 
 time later the lateral incisor began to get very sore, with a feeling of 
 pressure in the anterior part of the jaw on that side. The dentist 
 advised removing the pulp in the lateral, or removal of the bridge, 
 without further investigating the real cause of her condition. The 
 trouble is clearly shown in Fig. 609 to be due to an unerupted cuspid. 
 The effort of the cuspid to erupt resulted in pressure on the root of 
 the lateral incisor. Another case is shown in Fig. 610. The patient 
 said that the central incisor felt sore from time to time. Roentgen 
 examination showed an unerupted cuspid pressing against the root 
 of the central in its effort to grow out of the jaw. 
 
710 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 Unerupted and Impacted Molars.— The third molars being the last 
 teeth to take their position in the dental arch are most frequently 
 found to be unerupted and impacted. This is principally due to 
 underdevelopment of the jaws, which fail to grow large enough to 
 accommodate all the teeth. Their position in the jaw varies greatly. 
 They may be partly erupted but prevented from entire eruption by 
 a bulging distal surface of the second molar or the ascending ramus. 
 At other times they may be entirely unerupted. Unerupted teeth 
 are either in upright position, mesially or distally inclined, but are 
 sometimes at a great distance from their proper places. They may 
 be found in any part of the ramus or maxillary bone, as illustrated in 
 two cases in the author's text-book on Oral Roentgenology,^ first edition, 
 Figs. 33 and 189. 
 
 Unerupted molars are frequently the cause of obscure feelings of 
 pressure and neuralgic symptoms, which may be continuous, inter- 
 mittent or periodic. The pain may be intense, sharp, throbbing or 
 dull, and may be referred to distant parts of the face and head. Local 
 conditions, especially infection, are often associated with partly 
 erupted teeth. After the gum has been pierced by the cusps of the 
 tooth, an orifice is made which allows food and bacteria to enter 
 between the enamel of the tooth and its overlying soft tissue. The 
 condition frequently is aggravated by biting on the inflamed tissue 
 during mastication. The inflammation then spreads to the neigh- 
 boring tissue, causing a trismus of the muscles of mastication, so that 
 the mouth can be opened but very little. The submaxillary lymph 
 glands become enlarged and tender, with marked swelling on the side 
 of the face and neck. One sequel may be pharyngitis, sometimes 
 even leading to the formation of a pharyngeal abscess, simulating a 
 peritonsilar abscess. In the case of Mr. R. B. T. such a condition 
 is exemplified. He presented a history of repeated trouble with the 
 left lower third molar. The last attack was the worst, being accom- 
 panied by large swelling, difficulty in swallowing, trismus of the 
 muscles of the jaws and pus discharge around the tooth. He con- 
 sulted a laryngologist, as he thought the primary trouble was in the 
 throat. Roentgen examination (Fig. 611), however, disclosed an 
 impacted lower third molar with a large cavity in the crown, appar- 
 ently involving the pulp and causing an extensive infection of the 
 surrounding parts. 
 
 Another complication occurs if pressure exerted by the impacted 
 tooth causes absorption of part of the second molar. A good example 
 is shown in Fig. 612. The patient had suffered neuralgic pains for 
 
 1 Thoma, K. H. : Oral Roentgenology, Boston, M. C. Cherry. 
 
SPECIAL ROUMTGEN STUDY OF DEMTAL DISEASES 711 
 
 several weeks. The roentgen picture revealed a partly erupted upper 
 third molar, which caused pressure absorption on the distal surface 
 
 Fig. 611 
 
 Fig. 612 
 
 of the second molar to such an extent that khe pulp barely escaped 
 involvement. 
 
 Roentgen examination is the most valuable means, and sometimes 
 the only one, by which unerupted teeth can be discovered. The size 
 of the picture should be such as to include the entire tooth and 
 
 Fig. 613 
 
 a considerable portion of the surrounding structures. A roentgen- 
 ogram which shows only part of the tooth is, of course, sufficient to 
 
712 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 reveal its presence. To the surgeon who must remove it, however, 
 such a film is useless, for he needs exact information as to the number, 
 size and shape of the roots and the position of the tooth and its rela- 
 tion to the bone of the ramus. Fig. 613 shows an extra-oral picture 
 of an unerupted upper third molar impacted under the distal surface 
 of the tooth in front. Note also the root formation of the third molar 
 in the lower jaw. Another case is illustrated in Figs. 614 and 615. 
 The patient, aged nineteen years, suffered for several years with 
 periodic headaches, especially on the right side in the region of the 
 frontal sinuses, with indefinite subjective symptoms of pressure in 
 the back of the head. At times the pain disappeared entirely and 
 then a period of suffering followed. Roentgen pictures, showing 
 unerupted third molar teeth, had been taken two years before the 
 patient presented for examination. These teeth, however, apparently 
 did not exert pressure against those in front (Fig. 614), and were, for 
 this reason, considered innocent. Roentgen examination two years 
 
 Fig. 614 
 
 Fig. 615 
 
 after the first plates had been taken (Fig. 615) showed that the lower 
 molar had grown into a position which one would not have expected 
 from the position shown in the first plate (Fig. 614). It was decided 
 to remove all four third molar teeth, which resulted in complete relief 
 from all the symptoms. This case demonstrates the fact that pain 
 is often caused by the development of the roots of the teeth against 
 the inferior alveolar nerve. , ; 
 
 Supernumerary Teeth. — ^These may be well-formed teeth or in rudi- 
 mentary peg-shaped form. They may be erupted in natural position 
 or outside the dental arch. Fig. 616 shows a roentgen picture of the 
 jaw of a girl, aged seventeen years. The orthodontist has kept open 
 a space for the cuspid which was slow in erupting. A picture was 
 taken to find out what its position was. The roentgen finding, how- 
 ever, showed that the tooth about to erupt was a supernumerary 
 bicuspid, the cuspid being unerupted and quite a distance from its 
 normal place. In another case a small rudimentary molar was seen 
 
SPECIAL ROENTGEN STUDY OF DENTAL DISEASES 713 
 
 behind the second molar. The roentgen picture revealed a fourth 
 unerupted molar of normal size (Fig. 617). 
 
 Fig. 616 
 
 Fig. 617 
 
 Follicular and Dentigerous Cysts. — Other disturbances of normal 
 dentition of a more serious character are caused by abnormal develop- 
 ment of a tooth follicle during the developmental stage of a tooth. 
 Instead of a tooth a cyst may be formed, in which case it is called a 
 follicular cyst. Such cysts may be formed from the enamel organ 
 without the development of a tooth. In other cases, however, one 
 or more teeth may be found in the cyst, when it is called dentigerous. 
 Sometimes only masses of calcified tooth particles are produced, and 
 these may be composed of enamel, dentin, cement and dental pulp. 
 Occasionally they also contain bone. Such a lesion is spoken of as a 
 cystic odontoma. Calcified tissue, however, is not always formed, 
 and microscopic examination may show a mass of enamel organs 
 with cylindrical epithelial cells. Typical ameloblasts are sometimes 
 developed, and these may be found laying down enamel. This is 
 called a cystic adamantonoma. 
 
 The cyst sac is usually composed of a fibrous membrane lined by 
 epithelium, which may be in a single layer, stratified or epidermoid 
 in character. The liquid contained in the sac is clear and straw- 
 colored, originating principally from a secretion by the epithelial 
 cells. Cholesterin crystals are usually present, and if infection has 
 taken place it is contaminated by pus. 
 
 Roentgen diagnosis is of greatest help, as there is often little clinical 
 indication, and the symptoms may be very misleading. The roentgen 
 picture also gives valuable information as to the cause, extent and 
 type of cyst and helps in determining the mode of operation. Teeth 
 in dentigerous cysts can be located fairly accurately, which facilitates 
 
714 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 their removal. Extra-oral exposures or large intra-oral films should 
 be taken, as small ones seldom cover more than a part of the lesion. 
 The dark area representing radiolucency, due to absorption of bone, 
 is defined by a light line, the cortical layer of bone which forms the 
 wall of the bone cavity. 
 
 In the case of Si. (Fig. 618), a man, about sixty-five years old, the 
 patient complained of a bad-smelling fluid escaping from a sinus in 
 the third molar region. The second and third molars were missing. 
 The second molar had been extracted a short time before, but this 
 
 Fig. 618 
 
 did not improve the complaint. Roentgen examination by means of 
 a small dental film showed a dark area at the root of the first molar, 
 but no impacted tooth. A large plate was then taken (Fig. 618). 
 This shows a large dark area extending to the lower border of the 
 mandible and almost to the angle of the ramus. The area is sur- 
 rounded by a distinct light line, the typical picture of a cyst. The 
 third molar is found near the angle of the jaw. A diagnosis was 
 made of dentigerous cyst, infected from the mouth. In the case of 
 W. W. (Fig. 619), that of a boy, aged nine years, the following history 
 
SPECIAL ROENTGEN STUDY OF DENTAL .DISEASES 715 
 
 was given: his mother first noticed a swelhng in the left upper side 
 of the jaw in the cuspid region about one year previous to the con- 
 sultation. She thought it was the cuspid about to erupt. There 
 
 Fig. 619 
 
 Fig. 620 
 
 Fig. 621 
 
 was no pain or soreness. A little later the left upper first temporary 
 molar started to feel tender. It was filled, treated and refilled by a 
 dentist, and finally fell out. Nearly a year later a slight swelling on 
 
716 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 the left side of the face and side of the nose was noticed by his physi- 
 cian, who referred him back to the dentist, from whom he was sent to 
 the author. Physical examination revealed little besides the swelling 
 on the face. The alveolar process showed no signs of a cyst. Roent- 
 gen pictures, however, showed a large dentigerous cyst containing an 
 unerupted cuspid, apparently encroaching somewhat on the maxillary 
 sinus, and being located between the alveolar process, the nasal cavity 
 and the palatal process. In another case, that of a boy, aged sixteen 
 years, the patient noticed a swelling under his upper lip for several 
 months, the left upper central and lateral incisors being somewhat 
 tender to the touch. His dentist opened the left upper lateral incisor, 
 removed the pulp and treated the root canal. Whenever the root-canal 
 dressing was changed a yellowish fluid escaped through the tooth. 
 The treatments failed to help the condition and the gum was lanced 
 several times without result. The patient was sent in for consulta- 
 tion on November 8, 1918, at which time a roentgen picture (Fig. 
 620) was taken and from this and the clinical evidence a diagnosis of 
 cystic odontoma was made. Fig. 621 shows a microscopic picture 
 of the cyst with its contents. 
 
 Traumatic Injuries of Teeth. 
 
 Injuries, especially of the front teeth, are a frequent occurrence in 
 children and occasionally in adults with accidental injuries. The 
 teeth may become dislodged and sometimes are forced deep into the 
 tissues. A case of the latter type is exemplified in the following 
 patient: a young girl, as a result of falling down stairs, had a badly 
 cut lip and tongue. No teeth could be seen in the anterior part of 
 the upper jaw. The roentgenogram (Fig. 622) shows that the tem- 
 porary incisors were driven into the jaw, the permanent teeth escaping 
 injury. 
 
 Teeth which are loosened by an accident may be fractured or only 
 broken out of the process. A roentgen picture will help to determine 
 the condition. If no fracture has occurred and the tooth is retained 
 it should be examined from time to time to find out whether the pulp 
 remains normal. Fractures of teeth sometimes show plainly when 
 roentgenographed, especially when the fracture occurs in a transverse 
 direction or in a plane vertical to the film. If the plane of fracture 
 is parallel to the film there may be some difficulty in making a correct 
 diagnosis. The patient whose roentgen film is shown in Fig. 623 was 
 in a motor cycle accident. The upper front teeth were slightly broken 
 at the edges. The left upper incisor was very tender and there was 
 a slight swelling over the gum. The roentgen examination shows 
 
SPECIAL ROENTGEN STUDY OF DENTAL DLSEASES 717 
 
 fracture of the root. The small radiolucent area at the apex indicates 
 the beginning of an apical abscess. 
 
 Another case is shown in Fig. 624. From an accident the bicuspid 
 had been fractured in a horizontal plane, as can be seen in the illus- 
 tration, with a dark area indicating bone infection surrounding the 
 site of the fracture. 
 
 N 
 
 f \ ^ 
 
 Fig. 622 
 
 Fig. 623 
 
 Fig. 624 
 
 Fig. 625 
 
 Posts of crowns and bridge abutments are sometimes the cause of 
 a fractured root, as illustrated by the following case: the patient 
 whose roentgen ray is shown in Fig. 625 had a Richmond crown on 
 a second bicuspid. The gum was inflamed and the tooth sensitive. 
 Roentgen examination showed that the post had caused a vertical 
 fracture of the roots. 
 
 Dental Caries. 
 
 • Cavities in the incisors and occlusal surfaces of the posterior 
 teeth are easily recognized. Proximate cavities in molars and 
 bicuspids, however, are frequently overlooked and decay under 
 a filling often cannot be recognized before considerable harm has 
 resulted. The roentgen method has not yet come into general use to 
 
718 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 find obscure cavities in routine examination, but judging from inci- 
 dental findings in systematic search for infectious lesions it might be 
 well worth while to use the roentgen ray for this purpose. Decay 
 
 Fig. 626 
 
 Fig. 627 
 
 under fillings and crowns of various types may escape notice in the 
 most careful instrumental examination. Its timely recognition is, of 
 course, of greatest value not only in cases in which there is obscure 
 
 Fig. 628 
 
 Fig. 629 
 
 pain, but particularly to prevent the infection of dental pulps. Caries 
 is recognized in a roentgenogram as a dark area, due to increased 
 radiabib'ty, which is due partly to decalcification of the dentin by 
 
 Fig. 630 
 
 Fig. 631 
 
 bacterial ferments and partly to actual loss of tooth substance. Fig. 
 626 shows a roentgenogram of a molar tooth with a large cavity at 
 the distal surface. Figs. 627 md 628 show obscure cavities under 
 
SPECIAL ROENTGEN STUDY OF DENTAL DISEASES 719 
 
 fillings. In the first there was slight pain from hot and cold food; in 
 the two latter a neuralgic pain of the jaw, caused by the cavity at 
 the distal side under the cervical part of a filling. Fig. 629 shows 
 a crowned first molar with decay at the cervical margin on the distal 
 side. 
 
 When caries extends deep into the tooth substance it produces a 
 protective reaction, which very probably is also called into activity if 
 large fillings are inserted without an insulating layer of cement. The 
 irritating action of the infection, as well as chemical and thermal 
 influences, stimulate deposit of secondary dentin, which, of course, 
 decreases the size of the pulp chamber. This can be easily recognized 
 in any roentgen picture of the teeth. Fig. 630 shows upper incisors 
 with large cavities at both sides. The pulps have receded, due to 
 deposits of secondary dentin, filling the pulp canal in the crown entirely. 
 Fig. 631 shows recession of the pulp in an upper first bicuspid, due to 
 a large disto-occlusal filling. 
 
 Fig. 632 
 
 Fig. 633 
 
 Cavity Fillings. 
 
 Different filling materials have a different degree of radiability. 
 Porcelain cement fillings often appear the same in a picture as a 
 cavity, on account of their radiolucency. Oxyphosphate cements 
 also are more radiolucent than the substance of a tooth, and, there- 
 fore, give a similar picture. Metal fillings, of course, are com- 
 pletely radiopaque and gutta-percha offers a similar barrier to the 
 rays. Fig. 632 shows an upper central incisor with a gutta-percha 
 root canal filling. On its distal side a porcelain cement filling has been 
 inserted. Compare the radiability of the tooth with the porcelain 
 filling and the gutta-percha. Fig. 633 shows upper incisors with two 
 gold fillings in each central and another gold filling in the mesial 
 surface of the right lateral incisors. 
 
 Every dental roentgenologist could produce a large number of films 
 showing poor gold, amalgam, cement and gutta-percha fillings and 
 gold inlays. Large overhangs injuring the peridental mernbrane and 
 
720 
 
 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 alveolar bone, as well as lack of contact points giving occasion for the 
 formation of so-called food-pockets, are the most frequently observed 
 evils. A collection of such cases is shown in Figs. 634 to 639. 
 
 Fig. 634 
 
 Fig. 635 
 
 The first film (Fig. 634) shows amalgam fillings with rough over- 
 hangs extending down between the teeth, causing periodontal inflam- 
 mation and pockets. Fig. 635 shows lack of contact points between 
 
 Fig. 636 
 
 Fig. 637 
 
 the two molars and roughness of the filling in the second molar at 
 the cervical margin. Fig. 636 shows an extensive overhang at the 
 mesial side of a lower second molar, which was the cause of an inflam- 
 
 FiG. 638 
 
 Fig. 639 
 
 matory reaction of the investing tissues. In Fig. 637 am'algam fillings 
 of ragged outline are shown, with decay under the mesial portion of 
 the fillings, both in the first and second molar, as well as lack of proper 
 contact points. A gold inlay is shown in Fig. 638 in an upper second 
 
SPECIAL ROENTGEN STUDY OF DENTAL DISEASES 721 
 
 molar. There is lack of contact with the third molar tooth. Note the 
 feather edge at the cervical margin, distal side. Roentgen fihii (Fig. 
 639) shows a disto-occlusal gold inlay i,n the lower first molar, fitting 
 poorly at the cervical margin. Note also the poor filling at the distal 
 side of the second bicuspid, with decay underneath. 
 
 Restoration by Crown and Bridge-work. 
 
 A careful, systematic study of crown and bridge-work gives evidence 
 of the fact that very little attention is paid to the condition of the teeth 
 or roots, which are used as abutments. The problem is, by many, 
 regarded as a purely mechanical one, simply to restore the masticating 
 efficiency and the appearance, and any tooth which is useful as a 
 mechanical support is retained without investigation of its condition. 
 This short-sightedness often makes it necessary to destroy bridges of 
 very recent construction in order to remove an abutment which is 
 causing extensive periapical infection or to treat the root canal of a 
 tooth in which the pulp has become infected. 
 
 Roentgen Diagnosis before Planning Crown and Bridge-work. — 
 Before undertaking any restoration the teeth which are to be used as 
 abutments should be carefully roentgenographed. It is necessary to 
 determine whether a tooth is vital or whether its pulp is infected. If 
 it is devitalized the quality of its root-canal filling should be investi- 
 gated and possible bone infection around the apex of the tooth should 
 be discovered. If there be a chronic alveolar abscess present the out- 
 line of the root may be found to be either normal or pathologically 
 changed. In the latter case there may be absorption or hypercemen- 
 tosis of the apex. Sometimes unerupted teeth are discovered and 
 quite frequently there are broken-off roots, over which the gum may 
 have completely healed, in the alveolar process which is to be covered 
 by a bridge. Fig. 640 shows the case of a young man who had three 
 porcelain crowns on upper incisors. These crowns were of very good 
 appearance, but after a short time, when his general health became 
 poor, an acute process set in, causing acute suppurating ostitis of the 
 jaw. A roentgen picture, taken at this time, showed bone infection 
 around the roots, and the apical part of the pulp canals was entirely 
 unfilled. It also revealed partial root-canal filling in a bicuspid, to 
 which was attached a gold crown and dummy. This tooth also shows 
 slight infection around the apex of the root. Fig. 641 shows a case in 
 which a large fixed bridge had been constructed to replace several 
 missing teeth. Sometime after the bridge had been cemented into 
 place the central incisor began to get sore. A roentgen picture 
 revealed an unerupted cuspid pressing against the root of the incisor. 
 46 
 
722 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 Fig. 642 shows a small bridge attached to a vital bicuspid. When the 
 patient was seen she complained of soreness in the gum, and, without 
 
 Fig. 640 
 
 Fig. 641 
 
 a roentgen picture, one might have been led to believe that the pulj) 
 in the bicuspid had become infected. The picture, however, showed 
 
 Fig. 642 
 
 Fig. 643 
 
 Fig. 644 
 
 Fig. 645 
 
 that one of the apices of the first bicuspid had been left in the jaw 
 and the dark area around it showed there was a good-sized abscess 
 
SPECIAL ROmTGBN STUDY OF DENTAL DISEASES 723 
 
 connected with this root. Fig. 643 is a picture of a bridge made seven 
 years ago. The patient had no symptoms. Only the anterior abut- 
 ment is shown in this picture. There is a partial root-canal filling 
 and a large area around the apex, indicating bone involvement. The 
 floor of the antrum is clearly outlined. Examination of the antrum 
 revealed abnormal condition. There are also pockets at each side 
 of the tooth. Fig. 644 shows a bridge in the mouth of a patient who 
 had been suffering from arthritis for about a year. He had several 
 abscesses on other teeth. The illustrated bridge is attached to a 
 bicuspid with corkscrew root-canal filhng and a molar, which shows 
 decay at the mesial side under the crown. A root has been left under 
 the bridge and the patient complained of soreness of the gum. Clinical 
 examination showed an inflammatory condition, due to lack of hygiene 
 and probably also infection from the root. Fig. 645 shows a roentgen- 
 ogram of a patient who complained of slight pain on the right side of 
 the face and discharge from the nose. A roentgen picture of the 
 maxiUary sinuses verified the clinical findings of a diseased antrum. 
 Besides an infected pulp in the right upper first molar, due to decay, 
 there is a second bicuspid holding a small bridge. The pulp in the 
 bicuspid must have become infected, as evidenced by the changes 
 around its apex, which indicate the pathologic condition of the bone. 
 In addition there is an infected root underneath the dummy. 
 
 The Pulp of the Bridge Abutment. — Since our better knowledge of 
 the pathologic conditions, both local and systemic, so frequently 
 caused by devitalized teeth, we have been impressed with the serious- 
 ness of pulp extirpation. Whenever possible restoration should be 
 made without sacrifice of the pulps in normal teeth. If, however, 
 the pulp has become involved from decay, or if there is danger that 
 pathologic processes may start after the bridge is made, it is, of 
 course, better to consider its removal under favorable conditions. 
 A careful roentgen study should be made to determine whether root 
 treatment is advisable. The various steps in the root-canal treat- 
 ment should be checked up by means of other pictures, as described 
 later. It is a mistake to believe that a tooth must be devitalized for 
 the attachment of a gold or porcelain jacket crown. The author has 
 seen many roentgenograms of teeth which were perfectly normal after 
 carrying crowns for a long time. Fig. 646 shows an upper bicuspid 
 with a gold crown which has been on the tooth more than ten years 
 without causing any pathologic condition. Fig. 647 shows two jacket 
 crowns on a cuspid and bicuspid with normal pulps. 
 
 If pulp disease is found it may have started when the tooth was 
 prepared or chronic infection of the pulp and periapical tissues may 
 have existed before the crown was made. Again, the pulp disease 
 
724 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 may have been caused by decay starting under poorly fitting crowns 
 and unclean bridges or from improper root-canal work. Fig. 648 shows 
 a jacket crown on a tooth with signs of periapical infection, due to 
 
 \jXjg 
 
 Fig. 646 
 
 Fig. 647 
 
 chronic pulpitis. Fig. 649 reveals extensive chronic bone infection 
 around the root of a lateral incisor to which a porcelain crown had 
 recently been attached. The apical part of the canal is not filled, 
 
 Fig. 648 
 
 Fig. 649 
 
 the infection probably having existed before treatment was under- 
 taken by the dentist. Fig. 650 shows a first molar with a gold crown. 
 At its mesial side a cavity had formed, which almost separated the 
 
 Fig. 650 
 
 Fig. 651 
 
 mesio-buccal root. Fig. 651 is a roentgenogram of a patient who had 
 a slight infection at the apex of a bicuspid, the root canal of which 
 had not been properly treated before the bridge was attached. Note 
 also the large area around the cuspid. 
 
SPECIAL ROENTGEN STUDY OF DENTAL DISEASES T2'h 
 
 Technical Constraction. — Perfect mechanical results are quite as 
 important as proper diagnosis. Fixed bridges are, of course, contra- 
 indicated in patients who will not take proper care of their teeth 
 
 Fig. 652 
 
 Fig. 653 
 
 and mouth, and unless they are willing to have regular prophylactic 
 treatments and to do their part at home, removable bridge-work only 
 should be considered. Fig, 652 shows a bridge which caused infection 
 
 Fig. 654 
 
 Fig. 655 
 
 of the abutments and loss of almost all the alveolar structure on 
 account of septic conditions. In the bridge shown in Fig. 653 decay 
 had progressed underneath a crown to such an extent as to separate 
 
 Fig. 656 
 
 Fig. 657 
 
 almost entirely the roots from the crown. The fit, or misfit, at the 
 cervical margin can be shown up very nicely in roentgen pictures, as 
 seen in Fig. 654, which shows that a large surplus of cement has been 
 
726 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 left at the mesial side in the interproximate space. Fig. 655 shows a 
 crown with a large overhang at the mesial side. Fig. 656 shows the 
 very poor fit of a gold crown at the cervix, and in Fig. 657 an extreme 
 overhang at the margin of the mesial side is shown. 
 
 Fig. 658 
 
 Fig. 659 
 
SPECIAL ROENTGEN STUDY OF DENTAL DISEASES 727 
 
 Good work can also be proved by means of roentgen pictures. Figs. 
 658 and 659 show two cases in point. The first (Fig. 658) shows 
 a bridge mth inlay attachments in the lower jaw. The other picture, 
 Fig. 659, illustrates another case. Both of these show beautiful fits. 
 
 Pulp Disease and Treatment of Root Canals. 
 
 The greatest benefit the dentist has derived from the roentgen ray 
 is, without doubt, its use in diagnosing conditions of pulps and root 
 canals and to check up the progress of root-canal cleaning and filling. 
 This work has heretofore been very unsatisfactory, not only on account 
 of obscure conditions which could not be properly diagnosed, but, for 
 the same reason, because of the small percentage of perfect results 
 obtained. The following general conclusions of the result of root-canal 
 operation, performed without the aid of the roentgen method may 
 be drawn from examining many thousands of roentgenograms. 
 
 1. A very small percentage of devitalized teeth show perfect root 
 canal fillings. Of these some show entirely normal conditions of 
 the periapical tissue, as far as one is able to judge from a perfect 
 roentgen picture, while others reveal decided periapical changes 
 notwithstanding the fact that the whole canal, as far as the apex, may 
 have been filled. Whether such conditions are due to periapical 
 infection having occurred before the root canal operation was per- 
 formed, and having persisted, or whether they represent an infection 
 which took place during or after the filling of the canal, cannot be 
 ascertained. Fig. 660 is a roentgen picture of a tooth with a perfect 
 root-canal filling, done twenty-one years ago. The periapical tissue 
 appears normal. Fig. 661 shows a tooth with a perfect root-canal 
 filling and periapical infection. 
 
 2. A certain number of roentgen pictures show up accidents which 
 happened during the root-canal operation. The most frequent ones 
 are caused by motor-driven root-canal instruments. They are also 
 due to miscalculation of the direction of the canal or to crooked roots. 
 Fig. 662 illustrates a case in which a perforation is seen in the lateral 
 incisor. The channel, which is very large, extends to the distal side 
 and must have been made by a burr or engine reamer. Fig. 663 shows 
 another case. A first bicuspid, with a porcelain crown attached by 
 means of a post, revealed no visible root-canal filling, and the post 
 is seen to extend just through the distal surface of the root. There is 
 a radiolucent area both at the apex of the tooth and on the side, 
 indicating that infection has occurred in both places. 
 
 3. Poor root-canal fillings, on account of anatomic conditions or 
 Calcifications obstructing the canal, are not so frequently found as 
 
728 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 those due to faulty technic, which will be considered later. Fig. 
 664 shows an anatomic vagary which made a perfect root-canal 
 
 Fig. 660 
 
 Fig. 
 
 filling impossible. The root of the second bicuspid is very crooked, 
 but it must be admitted that even in this case a better result might 
 
 Fig. 662 
 
 Fig. 663 
 
 have been expected. In Fig. 665 the canal in the lateral is obstructed 
 by calcareous deposits and makes root-canal treatment impossible. 
 
 Fig. 664 
 
 Fig. 665 
 
 4. By far the largest percentage of poor root-canal fillings are 
 caused by improper and careless technic, and because before the use 
 of the roentgen ray there was no means of telling whether the operation 
 was successful or not. No doubt in most cases the work was done 
 
SPECIAL ROENTGEN STUDY OF DENTAL DISEASES 729 
 
 as well as possible under the circumstances, but toda}- there is no 
 excuse for working in the dark. A small percentage of partly filled 
 root canals show no periapical infection. Whether this is due to 
 
 Fig. 666 
 
 Fig. 667 
 
 perfect sterilization and aseptic methods or to antiseptic preparations 
 used in connection with the filling it is difficult to determine. Fig. 
 666 shows a lower bicuspid with the root only half -filled. Although 
 
 Fig. 668 
 
 Fig. 669 
 
 the tooth had been in this condition for many years the peridental 
 membrane and the bone around the apex show no changes whatever. 
 However, the majority of teeth with poor and incomplete root-canal 
 
 Fig. 670 
 
 Fig. 671 
 
 fillings show involvement of the periapical tissue, affecting not only 
 the peridental membrane but also the tooth tissue and the bone. 
 Teeth bearing porcelain crowns attached by means of posts invariably 
 
730 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 have poor root-canal fillings. This may be because crown and bridge- 
 workers do not pay enough attention to the proper treatment and 
 filling of root canals or because frequently the root filling is torn out 
 of the canal when using reamers to fit the post. Fig. 667 illustrates 
 such a case. Pictures of teeth showing partial filling, a broken instru- 
 ment in the canal, cork-screw filling and poorly condensed fillings 
 are presented in Figs. 668, 669, 670 and 671. 
 
 i k 
 
 Fig. 672 
 
 Fig. 673 
 
 Roentgen Diagnosis of Pathologic Changes of the Pulp. — 
 Secondary Dentin, Pulp Nodules and Calcifications. — These are the 
 only changes of the pulp which can actually be demonstrated in a 
 roentgenogram. In the case of secondary dentin the outline of the 
 root canal is changed, while pulp nodules and calcifications cause a 
 direct change in the radiability of the pulp. The nodules may be 
 round or oblong and calcifications may close up and obstruct the 
 entire lumen of the root canal. Fig. 672 is a picture of the left lower 
 
 Fig. 674 
 
 Fig. 675 
 
 molars of a patient who had worn down the occlusal surfaces of his 
 teeth. Secondary dentin had formed, decreasing the size of the pulp 
 chamber. Compare the size of the pulp chambers in the first and 
 second molars. Fig. 673 shows large calcareous deposits in the pulp 
 chamber of the first molar. Fig. 674 shows formation of calculi in 
 the canals of both central incisors. Note also the accessory foramen 
 in the left central incisor, Fig. 675 reveals 9, round pulp nodule in the 
 
SPECIAL ROENTGEN STUDY OF DENTAL DLSEASES 731 
 
 pulps of two upper molars. The patient had attacks of neuralgia at 
 intervals on this side of the face, which had become more severe, 
 including also the ear, three days before he was examined. Removal 
 of the pulps in both the second and third molars permanently relieved 
 all symptoms. In Figs. 676 and 677 calcareous deposits in the pulp 
 canals of teeth are shown. 
 
 Fig. 676 
 
 Fig. 677 
 
 Pulp Infection and Necrosis. — Inflammatory and infectious changes 
 cannot be directly demonstrated by means of the roentgen ray, but 
 by comparing clinical symptoms and roentgen findings it is sometimes 
 possible to make important discoveries. Fig. 678 is a roentgenogram 
 of the anterior teeth in the lower jaw. The patient had been suffering 
 a great deal of pain for two nights. A cavity is seen in the lateral 
 incisor near the cervical margin, extending close to the pulp. The 
 pain, therefore, is due to a pulpitis in this tooth and was caused by 
 
 Fig. 678 
 
 Fig. 679 
 
 infection from the decay. Another patient had been suffering from 
 neuralgic pain on the right side. Clinical examination revealed 
 nothing important, but there was a history of the pulp in the first 
 molar having been capped. Fig. 679 shows that the filling extends 
 close to the pulp. Slight changes are noticeable around the apices 
 of both roots, but these have not the appearance of typical periapical 
 infection. From these findings a diagnosis of necrosis of the pulp 
 in the first molar may be made. The operative findings confirmed 
 the diagnosis, 
 
732 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 Frequently it is possible to draw the necessary deductions from 
 the roentgenogram alone in order to make a diagnosis of pulp disease. 
 This is especially important in all cases of chronic pulpitis without 
 history or symptoms. As soon as the infection spreads from the 
 pulp through the apical foramen, changes can be demonstrated in 
 the periapical tissue. If these findings are seen connected with a 
 tooth in which the root canal has never been treated, and if, in addi- 
 
 FiG. 680 
 
 Fig. 681 
 
 tion, we can demonstrate some causative factor, the diagnosis of pulp 
 disease may be made with certainty. Fig. 680 shows periapical changes 
 around the roots of the upper first molar. There is also decay at 
 the cervical margin under the filling. The diagnosis, therefore, is 
 chronic pulpitis and periapical infection. Fig. 681 is an interesting 
 study. Periapical infection, apparently caused by pulp disease, is 
 revealed on all four lower incisors. Many porcelain cement fillings 
 and two gold fillings appear in the crowns. Whether the infection 
 
 Fig. 682 
 
 Fig. 683 
 
 originated because the patient neglected to have the cavities excavated 
 and filled when they were small or whether it was due to some action 
 of the porcelain cement is not so easily determined. Attention has 
 already been drawn to pulp disease caused by. crowns and bridges. 
 This is usually due to an infection having occurred before the crown is 
 cemented on the tooth (Fig. 682), or to decay which starts under the 
 gum or under a poorly fitting crown after the cement has washed out. 
 
SPECIAL ROENTGEN STUDY OF DENTAL DISEASES 733 
 
 Fig. 083 sliows such a coiulition in which l)ull> infection has been caused 
 by decay at the distal side luider the crown of the first bicuspid; there 
 is also decay under the inlay in the second bicuspid. 
 
 In the cases mentioned so far the infection of the i)uli) started from 
 the crown of the tooth and extended through the canal into the peri- 
 apical tissues. In some cases the infection travels along the peri- 
 dental membrane, forming a pus pocket at the side of a tooth. On 
 reaching the apex pulp infection occurs as illustrated in Fig. 684. 
 
 Fig. 684 
 
 Fig. 685 
 
 The patient had some pain in the left side of the low^er jaw, and after 
 a roentgenogram was taken the left lower first molar was extracted. 
 The symptoms continued oflF and on and did not entirely disappear, 
 A few days before the author saw the patient the pain had grown 
 worse and the second molar had become loose and sore. A roentgen 
 picture taken at this time is shown in Fig. 684. Apparently the pocket 
 had existed between the first and second, molar and is still visible in 
 
 Fig. 686 
 
 Fig. 687 
 
 the negative. The infection had spread from this pocket to the apex 
 of the second molar, causing infection of the pulp. 
 
 Another possibility of pulp infection is presented by the case shown 
 in Fig. 685. It discloses periapical infection on the lateral mcisor 
 w^hich had been treated. The tooth next to it, although perfectly 
 sound, with no cavity or filling, had an infected pulp, which reacted 
 to the heat test. It had become infected from the periapical infection, 
 which had spread from the neighboring tooth. 
 
734 ROENTGEN Diagnosis in operative dentistry 
 
 Prognostic Roentgen Examination before Treating Pulps or Root 
 Canals. — Before undertaking any pulp canal operation, no matter 
 whether the pulp be normal or diseased, it is absolutely necessary to 
 
 B«' 
 
 Fig. 688 
 
 Fig. 
 
 make a careful diagnosis of the condition of the root and root canal 
 by means of the roentgen ray. The root may show abnormal devel- 
 
 FiG. 690 
 
 Fig. 691 
 
 opment or deviations in the number, size and location of the root 
 canals. Fig. 686 shows two bent bicuspid roots and Fig. 687 a very 
 
 Fig. 692 
 
 Fig. 693 
 
 badly curved root of an upper first bicuspid. Root-canal treatment 
 would be contra-indicated in a case like this. 
 
Special roentgen study of dental diseases 735 
 
 The apical part of the tooth presents many variations besides decided 
 curves at the very end. We frequently find one or more accessory 
 foramina, and the number of root canals is not as staple as one might 
 be led to believe from the older text-books on dental anatomy. Two 
 canals are frequently found in the lower bicuspids; even three occa- 
 sionally, while the mandibular cuspids and incisors quite often have 
 bifurcated canals leading to a common foramen. The lower molars 
 sometimes present in each root two canals and the third molars are, 
 of course, always uncertain. In young teeth the apical foramen is very 
 large and funnel shaped (Fig. 688), while we sometimes find lack of 
 proper development in vital teeth, as seen in Fig. 689. The patient, 
 who had had orthodontic treatment, had a roentgen picture taken to 
 locate the permanent cuspid, which was missing. The roentgenogram 
 showed also a very peculiar condition at the apices of all four incisors, 
 from which one might be led to believe that absorption had taken 
 place. Fig. 690 shows a bifurcated root canal in a lower first bicuspid 
 and in Fig. 691 an accessory canal is shown in an upper central incisor. 
 Two canals are seen in both lower bicuspids in Fig. 692 and Fig. 693. 
 Pathologic changes outside the tooth, but closely connected with 
 the root canal, should also be properly diagnosed before deciding on 
 the method of treatment. The author has seen cases in which root 
 canals have been treated for months without ever getting a sterile 
 condition. Roentgenograms of these cases revealed conditions which 
 never could have been affected by root-canal medication nor by 
 thermal or electrolytic treatment. Necrosis of the cementum at the 
 apical part of the root and extensive bone infection, as well as enor- 
 mous cysts, are often revealed by roentgen examination. Such cases 
 are cited under the headings in which their pathology and diagnosis 
 are discussed. 
 
 The Roentgen Ray as an Aid in Root Canal Cleaning.— The 
 importance of the removal of every particle of pulp tissue, whether 
 normal or diseased, from the canal or canals of a tooth has only 
 recently b*een fully realized. It is also important to properly and 
 completely ream the root canal and to enlarge it slightly either 
 by mechanical or chemical means, so as to facilitate the filling of 
 the canal. The only safe and sure way to determine whether the 
 canal is properly prepared for successful filling is by taking roentgen- 
 ograms. If the operator has a roentgen machine by his chair he can 
 insert broaches and take pictures with the rubber dam on, developing 
 the films at once and so losing no time. When taking pictures the 
 rubber dam clamp should be removed and replaced with heavy liga- 
 tures, to avoid confusion in the picture. If the film is to be taken at 
 some future time, or if the patient is to be referred to a roentgenologist. 
 
736 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 fine wires witli looped ends can be inserted into the canals, together 
 with a root-canal dressing, after which the cavity is sealed as usual. 
 The process should be repeated until a picture shows the wire inserted 
 to the very end of the root. 
 
 Fig. 694 
 
 Fig. 695 
 
 The Roentgen Ray as an Aid in Root Canal Filling. — ^The 
 filling of root canals should also be checked up by means of 
 roentgen pictures. Gutta-percha or chloropercha, or the solution 
 
 Fig. 696 
 
 which forms when the root-canal point dissolves in the chloroform 
 and rosin when Callahan's method is used, are of radiopaque nature 
 
 Fig. 697 
 
 Fig. 698 
 
 and show clearly in the roentgenogram. This investigation should 
 be made immediately after the filling is placed in the canal, because 
 at that time it is easy to condense it further, press it deeper into the 
 
SPECIAL ROENTCEN STUDY OF DENTAL DISEASES 
 
 M 
 
 canal or remove it, so that it can be replaced by a more perfect one. 
 Figs. 694 to 698 show pictures taken for the cleaning and filling of the 
 canals of a lower molar. In Fig. 699 a root-canal filling with a so-called 
 "cap'ping" at the apex is shown. The canal in Fig. 700 is filled just 
 to the apex, and in Fig. 701 the canal filling of a central incisor is shown 
 to include both the main and accessory foramina. 
 
 Fig. 699 
 
 Fig. 700 
 
 Fig. 701 
 
 Checking up Devitalized Teeth by the Roentgen Method.^ 
 
 It is highly commendable to take roentgenograms of devitalized 
 teeth at certain intervals to find out whether they remain normal 
 or become absorbed and cause bone infection. If a slight periapical 
 infection existed when the root canal was treated the tooth should 
 again be examined after six months, and after one year to ascertain 
 whether the bone changes have been repaired. If this is found to be 
 the case it indicates that the tooth is sterile and is being tolerated 
 by the system. 
 
 Periapical Infection. 
 
 Before discussing the roentgen method of diagnosing periapical 
 infection it is first necessary to review briefly the pathology of such 
 conditions. The infection caused by pulp disease starts, as a rule, 
 at a natural opening of the root canal, the apical foramen. We, 
 however, occasionally find infection at the side of a root, generally on 
 account of accidental perforation of the root by an engine reamer or 
 other root-canal instruments. If such injury is followed by infection 
 an abscess may form at this point, and we speak of it as a lateral 
 abscess. Fig. 702 shows such a root with a lateral abscess. If a per- 
 foration is made between the roots of a multi-rooted tooth and infection 
 occurs it is spoken of as an inter-radicular abscess. Such a case is 
 shown in Fig. 703 in which the floor of the pulp chamber has been 
 perforated. 
 47 
 
738 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 Periapical infection originating from a diseased dental pulp may 
 follow either of two chains of pathologic changes. The first is of 
 a destructive nature and begins with a reaction causing all the symp- 
 toms of acute inflammation, while the other, from the beginning, is 
 characterized by a mild and chronic reaction, which starts and con- 
 tinues without giving any local symptoms. 
 
 Fig. 702 
 
 Fig. 703 
 
 Acute Periapical Infection. — This condition starts as acute perio- 
 dontitis and involves a violent inflammatory reaction of the tissue. 
 Serum and polymorphonuclear leukocytes infiltrate the tissue, causing 
 an increase in volume of the peridental membrane, which results in 
 the well-known symptom which gives the impression that the tooth 
 has become elongated. Purulent exudations soon accumulate, the 
 cells of the periodontal membrane and the surrounding bone being 
 destroyed, and the condition is then called an acute alveolar abscess. 
 This may spread and cause suppurating ostitis of greater extent or 
 else the pus may soon find an outlet to the surface via the Haversian 
 canals, which penetrate the outer cortical layer of the bone. When 
 the pus collects under the periosteum a reaction sets in at once, caus- 
 ing a widespread serous infiltration of the soft parts, cheek or neck. 
 Finally the pus burrows a channel through the soft tissue, forming a 
 fistula into the mouth, nose, maxillary sinus or outside of the face. 
 After this process of destruction has reached its climax nature makes 
 an attempt at repair and the acute symptoms disappear; but unless 
 the cause (a diseased pulp or necrosed root apex) is removed the 
 condition becomes chronic. In this stage it may last for an indefinite 
 period, with the fistula discharging pus if the destructive process 
 becomes more active, or closing up for a time if the defensive system 
 predominates, only to reopen with more or less marked subacute 
 symptoms when suppuration again becomes more active. 
 
 The roentgen picture shows at first an increased space between the 
 
SPECIAL ROENTGEN STUDY OF DENTAL DISEASES 739 
 
 alveolar socket and the apex of the tooth. This is a sign of perio- 
 dontitis. Pus, which accumulates in the cancellous part of the bone, 
 may cause a tremendous reaction in the tissues before enough bone 
 destruction has taken place to become visible in the roentgen picture. 
 At other times, especially if the apex of the tooth is near the surface, 
 the pus may gather under the soft tissues without affecting the bone 
 to any great extent, and so give no roentgenographic record. A case 
 which exemplifies this is that of a patient who had suffered from a 
 swelling under the lip for several days. Clinical examination showed 
 a protruding upper lip and large swelling on the gum. The anterior 
 teeth in the upper jaw had large fillings, gold in the lateral and porce- 
 lain in the central incisor. Both were loose and tender to the touch. 
 Fig. 704 shows no radiolucent area, as might perhaps be expected with 
 such large abscess formation. The lateral incisor was opened and the 
 pulp found to be very putrescent. An incision on the labial part of the 
 gum released about an ounce of pus. 
 
 Fig. 704 Fig. 705 Fig. 706 
 
 Sometimes, however, the bone becomes extensively involved before 
 an outlet is made. In such cases a large radiolucent area is usually 
 found around the apex of the tooth. A case of acute alveolar abscess 
 of this nature is seen in Fig. 705. The central incisor had recently 
 been filled on the labial side. The tooth then started to ache and the 
 condition became worse. When examined the left central incisor was 
 very loose and tender and the two neighboring teeth were also slightly 
 affected. The gum was swollen and the lip protruded. Roentgen 
 examination showed a large radiolucent area, apparently starting from 
 the left central incisor. The infection must have spread from the pulp 
 to the bone, causing extensive suppurative ostitis. 
 
 When the acute stage is over the bone destruction, of course, is 
 still recognizable in the roentgen picture, although the outer swelling 
 
740 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 may have disappeared entirely. Slight pus formation continues in the 
 chronic stage, the exudation either being absorbed or discharged 
 through a fistula when there is sufficient accumulation. Fig. 706 
 shows a case of chronic alveolar abscess which had become more 
 active. The pulp was infected, and when the roentgenogram was 
 taken the patient was having a subacute attack. The amoimt of 
 bone dissolved is clearly indicated by the radiolucent area. 
 
 Blind Abscess or Dental Granuloma. — The difference between an 
 acute alveolar abscess and a blind abscess, or dental granuloma 
 should be clearly understood. The former is a suppurative inflam- 
 mation and involves a process of destruction of the peridental tis- 
 sues, dissolving them into pus. The latter is a reaction to a mild 
 injurious agent, stimulating inflammatory new growth as we see in 
 specific infections, as the tuberculous granuloma (tubercle) and the 
 syphilitic granuloma (gumma, syphiloma). Active suppuration does 
 
 Fig. 707 
 
 not occur at first, but an exacerbation may change the pathologic 
 picture so as to simulate a typical acute alveolar abscess. The blind 
 abscess, or granuloma, begins and continues to grow without giving 
 any symptoms. The defensive system of the body takes care of the 
 slight amount of pus formed, which is absorbed through the lymphatics 
 or blood channels. When speaking of a blind abscess, therefore, we 
 must think of a focal accumulation of leukocytes and lymphocytes 
 in the newly formed granulation tissue rather than of a cavity filled 
 with pus. Sometimes a dental granuloma is described as being a 
 tumor, but this is not correct, as it is distinctly of infectious origin and 
 histologically presents a picture of chronic inflammation. 
 
 The disease, of course, spreads at the expense of the bone. After 
 the stratum durum of the alveolar socket has disappeared the infec- 
 tion spreads into the medullary spaces, destroying the trabeculi3e 
 of the cancellous part of the bone. The process, however, is not 
 
SPECIAL ROENTGEN STUDY OF DENTAL DISEASES 741 
 
 always restricted to the inner part of the bone. When the tooth 
 apex is near the surface, or if the lesion is extensive, the outer cortical 
 layer frequently becomes involved. The Haversian canals are next 
 
 Fig. 708 
 
 Fig. 709 
 
 implicated and enlarged, a condition which Is easily recognizable in 
 a skull, by the many small holes on the surface of the bone (osteo- 
 porosis) (Fig. 707). The outer plate may be attacked so extensively 
 
 Fig. 710 
 
 Fig. 711 
 
 that a part of it disappears entirely, as seen in Fig. 708. It is evident 
 that if a hole has formed in the outer wall of the bone the picture 
 of the abscess cavity will be much more intense (Fig. 709). Similar 
 
 Fig. 712 
 
 bone infection is shown around two old decayed roots of a lower molar 
 in Fig. 710, as illustrated by a similar case in the upper jaw shown in 
 If the disease spreads it may result in a regular granulating 
 
 Fig. 711 
 
742 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 ostitis, as showr in Fig. 712, where the infection caused extensive bone 
 
 destruction without giving symptoms or causing excessive suppuration. 
 
 The first reaction which occurs in the peridental membrane is 
 
 Fig. 713 
 
 Fig. 714 
 
 called proliferating periodontitis, which appears in the roentgen 
 picture as a dark shadow of very moderate size. Fig. 713 shows a 
 devitalized cuspid, with partial root-canal filling and a slight radiolu- 
 
 FiG. 715 
 
 Fig. 716 
 
 cent area at the very apex of the tooth. A proliferating periodontitis, 
 but a slightly more extensive one, is seen in Fig. 714, where a cuspid 
 with partial root-canal filling is involved. The dark area around 
 
 Fig. 717 
 
 Fig. 718 
 
 the apex is slightly larger. Figs. 715 and 716 show blind abscesses, or 
 granulomata, of usual size, both on lateral incisors. There is a fine 
 difference in the two pictures. Fig. 715 shows a blind abscess of the 
 
SPECIAL ROENTGEN STUDY OF DENTAL DISEASES 743 
 
 granulating ostitis type, while Fig. 716 shows a granuloma which would 
 develop into a periodontal cyst. The difference in the roentgeno- 
 graphic aspect of these conditions lies in the light outline of the dark 
 area in Fig. 716, which is typical of cyst pictures (see paragraph on 
 Periodontal Cysts) . It is a common occurrence to find blind abscesses 
 of larger size, such as that seen in Fig. 717 on two teeth. Note the 
 gradual change from diseased to normal tissue. This is typical and 
 indicates the spreading character of the disease. Fig. 718 shows a 
 larger area still, which is usually spoken of as granulating ostitis. 
 More extensive cases are described under a special heading on bone 
 disease. 
 
 It should be noted that the roentgenogram does not show whether 
 the periapical infection is of acute or chronic character. It shows 
 loss of bone and, on account of the space where the bone has been 
 destroyed being radiolucent, a dark area appears in the picture. 
 The density of this area in the film depends upon various factors. If 
 the abscess cavity is shallow and on the surface, or inside the jaw 
 only, with massive cortical layers of bone on each side, as in the man- 
 dible, the radiability is but little affected. When, however, the 
 cavity is large in proportion to the thickness of the bone, or with 
 a large opening through the outer or inner wall of the bone, the radi- 
 ability greatly increases, resulting in a well-defined dark picture. 
 The contents of the abscess cavity affects the radiability very slightly; 
 whether it is filled with liquid pus or inflammatory granulation tissue 
 makes little difference. A large amount of cholesterin, however, may 
 decrease the radiability, as the author had occasion to observe once 
 or twice, when the abscess almost looked as if it had healed. 
 
 The fact that blind abscesses develop and exist without causing 
 pain or giving other local symptoms of inflammation makes their 
 discovery impossible without the use of the roentgen ray. Teeth with 
 necrotic roots and extensive involvement of the surrounding bone 
 often remain in the jaw of the unsuspecting individual, unrecognized by 
 the dentist unless he makes careful roentgen examination of all the 
 teeth. 
 
 The importance of recognizing such conditions is clearly proved 
 if cultures are made from the pus-soaked tooth after its extraction, 
 although its odor should be sufficient proof. It is today almost an 
 offence of negligence to give an opinion as to the condition of a patient's 
 mouth without first making a careful roentgen diagnosis. 
 
 Complications Caused by Periapical Infection. — When considering 
 the frequent occurrence of these localized bone abscesses around the 
 teeth it is surprising that one does not encounter more often a spreading 
 of the infection to adjoining teeth, extensive involvement of the jaws 
 
744 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 and adjoining cavities of the face. The reason for the infection re- 
 maining locahzed on one tooth is not easily explained, but one seldom 
 gets involvement of the teeth on each side if they are perfectly normal. 
 In Fig. 719, however, we see a devitalized lateral incisor with partial 
 root-canal filling and periapical infection. The picture of the abscess 
 cavity shows that it is connected also with the root of the central 
 incisor, the root canal of which has never been opened. The patient, 
 after being told of the condition, did not believe that it was of any 
 consequence, as it had never given her any trouble. Nothing was 
 done to either of the teeth. She came to the office two days later 
 with well-marked symptoms of pulpitis in the central incisor. A 
 similar case is shown in Fig. 720. The diseased pulp in the left central 
 with a porcelain filling apparently attached with two platinum posts 
 caused infection of the right central, which was otherwise entirely 
 normal. Infection and pus discharge sometimes persists after extrac- 
 
 // 
 
 Fig. 719 Fig. 720 
 
 tion of a tooth. This may be due to the fact that two teeth were 
 involved. If, for example, treatment had been undertaken in the 
 case shown in Fig. 719 without having a roentgen diagnosis made, prob- 
 ably only one tooth would have been extracted, the other giving no 
 clinical symptoms. The abscess on the second tooth would, of course, 
 have continued as long as the tooth was retained. Such a case is 
 presented by a patient who had a lower second bicuspid extracted. 
 Pus, however, continued to discharge through the alveolar socket 
 where the tooth had been removed. The roentgen picture is shown in 
 Fig. 721 and clearly discloses an abscess around the apex of the first 
 bicuspid, with a definite channel to the place where the other tooth 
 had come out. 
 
 Bone infection is, however, not always eliminated by simply extract- 
 ing the tooth. This is shown in the next case. The patient said 
 that the upper lateral incisor had been opened and the pulp removed 
 
SPECIAL ROENTGEN STUDY OF DENTAL DISEASES 745 
 
 two years previous to examination. The root was perforated and 
 finally extracted a year and eight months later. When seen by the 
 author a boil had formed near the wing of the nose. The roentgenogram 
 in Fig. 722 shows the condition. A bridge had been attached to the 
 cuspid to replace the lateral incisor and in the bone is seen a dark area, 
 which indicates the site of the original abscess cavity. When opening 
 it from the labial side of the gum it was found to be filled with inflam- 
 matory granulation tissue, containing a slight amount of pus. 
 
 In another case the nasal cavity was involved. The patient had 
 a swelling of the face and complained that for two days pus had 
 discharged from her nose. The upper central incisor was very sore 
 and a roentgen examination was resorted to for diagnosis of the 
 condition. Fig. 723 shows the picture in which a dark area is seen 
 over the central incisor. The tooth had a necrotic pulp, and after 
 extracting it a probe could be passed into the nose through a fistula. 
 
 n 
 
 Fig. 721 
 
 Fig. 722 
 
 Fig. 723 
 
 Infection of the maxillary sinuses has already been dealt with at 
 length under a separate heading. The importance of careful investi- 
 gation of the teeth in sinus disease cannot be impressed too strongly. 
 
 Other more serious complications are seen by the oral surgeon in 
 increasing numbers and quite frequently are entirely overlooked by 
 the dentist, or are improperly diagnosed. Among these belong the 
 various bone infections and periodontal cysts, which are also of infec- 
 tious origin. Such diseases will be considered under a special heading. 
 
 Condition of the Tooth Apex. — Periapical infection, especially if it is 
 of long standing, causes changes in the cementum of the tooth. Nutri- 
 tion is usually disturbed, the cells of the apical part of the periodental 
 membrane may become destroyed and the cementum, which is very 
 porous and easily absorbes the products of inflammation, becomes 
 pus-soaked. In this condition the tooth becomes an obnoxious 
 foreign body, which nature tries to eliminate. Osteoclastic absorp- 
 
746 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 tion starts on the surface of the cement, which then presents a rough- 
 ened appearance. Marked indentations are formed and the cement, 
 and later also the dentin, dissolves. The recognition of this condition 
 in a roentgen picture is of greatest importance, because it indicates 
 that only one kind of treatment is possible, either root resection or 
 extraction. The apex, in such a state, is a dead piece of bone, and, 
 like a sequestrum, has to be removed before healing can take place. 
 
 Fig. 724 
 
 Fig. 725 
 
 There is no medicinal treatment which could restore such a tooth to 
 its normal condition. If the periapical infection is of recent origin 
 the outline of the root is usually well defined and clear in a roentgen- 
 ogram, which shows that the cementum has not been attacked as 
 yet. Fig. 715 illustrates such a case. When the cement becomes 
 affected first an indistinct outline of the apex of the root only may 
 be observable. Later we can see resorption of the root, due to osteo- 
 clasia. Fig. 724 shows a lateral incisor and a cuspid with periapical 
 
 Fig. 726 
 
 Fig. 727 
 
 infection. In both teeth resorption is clearly indicated at the root 
 apex. In Fig. 725 a central incisor with partial root-canal filling is 
 seen showing a peculiar dark area, indicating resorption at the side 
 of the apex. Two upper bicuspids with decided loss of tissue at the 
 apices are shown in Fig. 726. A similar case, in which the disease 
 has become more extensive, is illustrated in the roentgenogram of a 
 cuspid (Fig. 727). Careful study is necessary to detect resorption on 
 
SPECIAL ROENTGEN STUDY OF DENTAL DISEASES 747 
 
 the mesial root of the first molar in Fig. 728. The distal root shows 
 only a roughness, which may be hardly noticeable in the printed 
 reproduction of the negative, on account of loss of detail, while a 
 perfectly normal outline of the cement is seen on the roots of the 
 twelve-year molar. 
 
 Fig. 728 Fig. 729 
 
 Hypercementosis in various stages may be found in connection 
 with some of these infections, due to the stimulation of some cemento- 
 blasts, which have survived. Fig. 729 shows such a condition on the 
 mesial root. Loss of tissue can be noticed at the very apex, but on 
 both sides of the root end a decided enlargement has taken place. 
 It is not necessary to mention that this makes extraction much more 
 difRcult. 
 
 Bone Repair Following the Treatment of Periapical Infections. — 
 The roentgen picture not only serves to diagnose properly the extent 
 of the involvement of the periapical tissues, that is, the bone and 
 tooth root, but furnishes also a means of checking up the progress 
 of bone repair no matter whether the treatment was medicinal, electro- 
 lytic or surgical. It should be remembered that bone formation is 
 the only thing shown and that it takes from six months to a year for 
 healing to be distinctly noticeable. One should not, however, be too 
 optimistic when a change is found in the roentgen picture, as a tem- 
 porary improvement may, for some time, decrease the extent of bone 
 inlection but does not necessarily imply a cure. It is also important 
 to regulate the exposure and development so that the two pictures 
 to be compared are about the same in these respects and the contrast, 
 density and angle of exposure will be parallel in the two films. If 
 healing is progressing properly bone bridges should be seen filling 
 the cavity in a uniform manner. 
 
 Figs. 730 to 732 show a case in which root-canal treatment was 
 started in December, 1916, under strictly aseptic care. Ionization was 
 employed and the canal filled after the treatment was completed. 
 Fig. 731 shows the root-canal filling and progress of healing after a 
 period of three months. In December, 1919, a new film was taken. 
 
748 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 This is shown in Fig. 732 and reveals definite resorption at the apex 
 of the root, although the abscess area at the side of the tooth has 
 healed. 
 
 Fig. 730 
 
 Fig. 731 
 
 Fig. 732 
 
 ^ T^ 
 
 Fig. 733 
 
 Fig. 734 
 
 Fig. 735 
 
 Fig. 736 
 
SPECIAL ROENTGEN STUDY OF DENTAL DISEASES 740 
 
 i\.iiotlier case of periapical infection, on a lower second molar, is 
 shown in Fig. 733. The pulp in this tooth had recently become infected. 
 It was removed and the root canal treated from May 2 to May 15, 
 1919, and filled on May 23. The condition at that time is shown 
 in Fig. 733. A new picture, taken March 1, 1920 (Fig. 734), records 
 the healing as it had progressed up to that time. 
 
 After apicoectomy, or root resection, the heahng process can also 
 be checked up by the roentgen method. A film should be taken 
 immediately after the operation for use later in comparison. Fig. 
 
 735 reproduces a roentgen picture taken just after such an operation. 
 The apices of the two upper incisors were resected and the dark area 
 in the bone around these roots represents the size of the cavity. Fig. 
 
 736 shows the same case after two years. The former abscess cavity 
 had entirely filled in with bone. 
 
 Alveolar Infection. 
 
 Injury and infection of the gingivse and the neck of a tooth causes 
 an inflammatory condition which can easily be recognized in the 
 mouth if careful examination be made. There are a great many 
 causes for gingival inflammation, the chief one being traceable to poor 
 dentistry in such work as fillings, pooHy fitting crowns and lack of 
 contact points between the teeth. Such dental shortcomings have 
 already been discussed in the chapter on these subjects. The inflam- 
 mation next spreads to the periodontal membrane and attacks the 
 cervical part of the alveolar process. At this stage changes are 
 visible in roentgenograms. At first an irregular outline is seen on the 
 bone edge between the teeth ; later when the disease spreads along the 
 root of the tooth, more bone becomes absorbed, so that a pus pocket 
 forms at the side of the tooth, progressing generally in a vertical 
 direction. On account of the bone being replaced by inflammatory 
 gi'anulation tissue a picture of a pocket is clearly recorded in the 
 roentgen film, and, as a rule, the cause is also discernible. Inter- 
 radicular infection sometimes results from cervical infection of the 
 alveolar process, the disease spi-eading to the alveolar septum betw^een 
 the roots of a multi-rooted tooth, often forming an abscess, which 
 closely resembles clinically any of the stages of an acute alveolar 
 abscess, due to disease of the dental pulp. The roentgen picture, 
 therefore, is an important means of differential diagnosis. Fig. 737 
 shows a pocket on both the mesial and distal sides of the first bicuspid, 
 caused by a poorly fitting gold crown. Fig. 738 reveals a large pocket 
 between the second bicuspid and molar. The space between these two 
 teeth was constantly filled with stagnant food. In Fig. 739 another 
 
750 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 large pocket between two molars is shown. This condition was 
 probably caused by lack of contact between the two teeth. Fig. 740 
 illustrates a case in which there was a pocket between the two molars 
 
 Fig. 737 
 
 Fig. 738 
 
 Fig. 739 
 
 * 4 
 
 Fig. 740 
 
 Fig. 741 
 
 Fig. 742 
 
 Fig. 743 
 
SPECIAL ROENTGEN STUDY OF DENTAL DLSEASES 751 
 
 in the lower jaw. The contour of the gold crown on the molar was 
 not sufficiently built out to close the space. In Fig. 741 the cause of 
 a pocket between a bicuspid and molar is seen to be due to an over- 
 hanging gold crown and also to some excess filling material which was 
 left between the gold crown and the distal side of the bicuspid. In 
 Fig. 742 an inter-radicular abscess appears on a lower molar. It was 
 caused by a pus pocket and inflammation of the gum at the buccal 
 side. Fig. 743 also shows an inter-radicular abscess. The dark area 
 between the roots indicates the abscess, which has replaced the bone 
 of the alveolar septum, and at the inner surface of the roots deposit 
 of serumal calculus can be seen, which leads to the conclusion that 
 the condition has existed for a considerable time. 
 
 Pyorrhea Alveolaris. — Pyorrhea alveolaris can be demonstrated 
 roentgenographically just as soon as the bone becomes involved. If 
 one roentgen picture of only part of the mouth is examined and an 
 occasional pus pocket is found a diagnosis of pyorrhea should never 
 be made, as this may be due to some local traumatic cause. It is 
 necessary to have clinical confirmation of roentgen diagnosis of 
 alveolar infection and pus pockets on most of the teeth, as pyorrhea 
 is not a disease which confines itself to one part of the mouth. Roent- 
 gen evidence is especially valuable to show the extent of the disease 
 an,d the amount of bony support which remains to hold the teeth 
 firmly in place. In the early stages we see only an irregular outline 
 at the alveolar margin, the compact part having been destroyed, so 
 that the outline of the bone between the teeth is irregular and has 
 a spongy appearance. Later the stratum durum, the cortical part 
 of the alveolar socket, becomes dissolved and a wider space than is 
 normally occupied by the peridental membrane can be seen between 
 the tooth and bone. More and more of the bone is then destroyed 
 and regular pockets form. In cases of very long standing w^e may 
 find places where the entire alveolar socket has disappeared, leaving 
 a funnel-shaped pocket, the alveolar bone between the teeth often 
 being entirely destroyed, so that finally the teeth are only supported 
 by the gum and consequently become extremely loose. At this stage 
 a pulpitis usually sets in, sometimes causing an acute alveolar abscess. 
 The cementum of the tooth not only becomes pus-soaked, but also is 
 covered with scales of serumal calculus, which can easily be discerned 
 in a good roentgen film. The roentgenogram reveals principally 
 pockets at the sides of the teeth, and, while these may be extremely 
 deep, there may be sufficient bone lingually and buccally to support 
 the tooth, so that it appears very firm. On the other hand large 
 pockets may exist at the labial and lingual surfaces when the roentgen 
 picture shows normal bone at the mesial and distal sides. 
 
752 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 The illustrations are all of one part of the mouth, showing various 
 degrees of pyorrhea. The same condition could be demonstrated 
 
 Fig. 744 
 
 Fig. 745 
 
 Fig. 746 
 
 Fig. 747 
 
 Fig. 748 
 
 Fig. 749 
 
 Fig. 750/' 
 
 Fig. 751 
 
 on other teeth. Fig. 744 shows a case in which there was a perfectly 
 normal condition of the alveolar process. Note the normal peridental 
 
SPECIAL ROENTGEN STUDY OF DENTAL DISEASES 753 
 
 membrane, the stratum durum lining the alveolar sockets and con- 
 tinuing as a dense layer of bone at the alveolar margin between the 
 teeth. Fig. 745 shows a case in which the bone has just started to 
 become involved. Figs. 746 and 747 both show loss of bone between 
 the teeth. The marginal part of the alveolar bone shows a spongy, 
 irregular appearance, but no deep pockets have been formed. Figs. 
 748 and 749 are two cases in which the pockets have formed at the 
 sides of the teeth, indicated by the dark, wedge-shaped spaces along 
 the roots. Fig. 750 shows an extreme case in which extensive bone 
 destruction has occurred around the mesial root of the first molar. 
 The inter-radicular septum of the tooth has also been entirely lost. 
 The pulp is probably infected and calcareous deposits are seen at 
 the distal side of the first bicuspid and on the molar roots. Fig. 751 
 shows the lower incisors of a pyorrhea case, with large deposit of 
 salivary calculus at the alveolar margin. 
 
 Bone Infection. 
 
 If we consider the frequency of dental infections it is surpris- 
 ing how rarely we find very extensive bone infection and serious 
 involvement of the adjoining structures and the alveolar process. 
 The reason for this is probably to be found in the bountiful blood 
 supply of the bone in the immediate neighborhood of the roots 
 of each tooth, from which a defensive system is built up to prevent 
 the spreading of infection, carrying away the products of bacterial 
 activity so successfully that there is but seldom an outlet or fistula 
 formed to the face or gum. Peridental infections sometimes result 
 in extensive lesions of the jaw, as well as radicular or periodontal cysts, 
 which are also of the infectious type. It is a deplorable fact that 
 they are generally not recognized for a long time and the general 
 practitioner of dentistry often treats devitalized teeth associated 
 with large bone infections for months by means of root-canal medica- 
 tion without making an accurate diagnosis, and, therefore, the jaws 
 are frequently seriously involved when the patient finally consults a 
 roentgenologist or oral surgeon. Every operator should be familiar 
 with various types of bone infection and recognize them clinically and 
 roentgenographically. 
 
 Diffuse Osteomyelitis. — Diffuse osteomyelitis of the jaws is, for- 
 tunately, a rare occurrence. The author has seen only five typical 
 cases during the past five years. One, in the upper jaw, healed rapidly 
 after the removal of several sequestra. The other four, occurring in 
 the mandible, were much more serious. In one case there was spon- 
 taneous fracture at the angle of the jaw before the patient noticed 
 48 
 
754 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 any diseased condition. In all of these cases the disease was very 
 stubborn, new sequestra formed continually, involvement of formerly 
 unaffected parts could not be prevented and with the best of care it 
 took months for complete recovery. 
 
 Fig. 752 
 
 Fig. 753 
 
 For comparison, Fig. 752 shows the anterior part of an entirely 
 normal upper jaw. Fig. 753 reveals a blind abscess, or granuloma, on a 
 devitalized central incisor. In diffuse osteomyelitis we find roentgeno- 
 graphically, at first, a rarefied condition in the entire cancellous part 
 
 ■ 
 
 ■ 
 
 1 
 
 
 
 ■ 
 
 W 
 
 m 
 
 K 
 
 ^P 
 
 
 KIm 
 
 F 
 
 
 
 9Hi 
 
 
 
 
 
 
 i 
 
 ] 
 
 •j 
 
 1 
 
 
 4 
 
 i 
 
 Fig. 754 
 
 Fig. 755 
 
 of the jaw. This is due to changes caused by infection in the marrow 
 spaces. Figs. 754 and 760 show the typical appearance of the first 
 stage of the disease. Later necrosis sets in, sequestra are formed, and, 
 in the roentgen picture, channels are seen which can be compared with 
 
SPECIAL ROENTGEN STUDY OF DENTAL DISEASES 755 
 
 the appearance of worm-eaten wood. Fig. 755 shows a case of osteo- 
 myeUtis with bone necrosis in the upper jaw. The patient, a girl, 
 aged nineteen years, complained that her mouth had been feeling 
 sore for about eight months, although two teeth had been extracted 
 and replaced by a bridge. The bridge was later taken off and the 
 gum lanced without giving relief. When the patient was presented 
 for consultation a roentgen picture was taken at once, which showed 
 a typical case of osteomyelitis with bone necrosis. When operated 
 upon a large sequestrum was found loose and removed with the 
 left upper central incisor and first bicuspid attached to it. There 
 were also two other bone sequestra found. The healing progressed 
 quickly and without complication. Another case is shown in Fig. 
 761, the earlier stage of which appears in Fig. 760. The patient, Mrs. 
 
 Fig. 756 
 
 Fig. 757 
 
 L., had been in perfect health. On December 24, 1915, she had a 
 tooth "capped" by her dentist. December 26 the tooth was extracted 
 by another dentist on account of an abscess. December 28 the 
 patient went to the hospital and received palliative treatment. On 
 January 18, 1916, she complained of pain in the entire lower jaw, 
 inability to open her mouth and soreness of the teeth. Temperature, 
 99.5° F. Examination revealed that the only teeth of the mandible 
 present were the front ones from the left lower first molar to the right 
 lower second bicuspid. All these teeth were extremely loose and 
 there was evidence of the right lower first molar having recently been 
 extracted. All the remaining upper teeth were firm and in good 
 condition. At first the roentgen plates showed only a rarefied area 
 extending from one side of the mandible to the other. Surgical 
 
756 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 treatment was started at once and several sequestra removed. The 
 disease spread as far as the angle of the jaw on the left side, when, 
 on March 2, the roentgen picture showed the more advanced stage 
 seen in Fig. 761. 
 
 Ostitis. — This is a bone infection of a more extensive type, developing 
 often from periapical infections. It may be of the suppurative type, 
 accompanied by violent acute symptoms, but more often is of a chronic 
 character, developing from chronic periapical infection. This type 
 is called granulating ostitis. It may involve large portions of the 
 jaw and several teeth without causing much swelling or pain. A fistula 
 is seldom formed, and when it does occur is due to an exacerbation 
 causing more active pus formation. It may lead to the nose, the 
 mouth, the outside of the face or the maxillary sinuses. The roentgen 
 
 Fig. 758 
 
 Fig. 759 
 
 picture shows an area of dark appearance, usually of irregular outline, 
 with very indistinct margins, due to a gradual change from healthy to 
 diseased tissue. Fig. 756 shows a case of gtanulating ostitis of large 
 dimensions. Compare this picture with Figs. 752 to 759 and note 
 the difference in the general appearance and outline. 
 
 Radicular or Periodontal Cysts. — The radicular cyst is of inflam- 
 matory, infectious origin and is developed from a blind abscess, or 
 granuloma, a chronic inflammatory lesion M^hich forms at the apex 
 of an infected tooth. Epithelial rests, remnants from the enamel 
 organ, are frequently found in the normal peridental membrane and, 
 through irritating influences, such as those exerted by chronic inflam- 
 mation, these are caused to proliferate, forming chains of epithelium 
 which grow like a network through the lesion. Having a tendency 
 
SPECIAL ROENTGEN STUDY OF DENTAL DISEASES 757 
 
 to grow between vital and necrosed tissue the epithelium soon forms 
 an entire lining of the abscess cavity. Accumulation of broken-down 
 tissue and exudates causes extension of the cyst. It often grows to 
 tremendous size at the expense of the bone, which disappears through 
 pressure absorption. The bone may become so thin that a cracking 
 sound can easily be heard on palpation. In the upper jaw cysts may 
 encroach on the nasal cavity or develop inside the maxillary sinus, 
 sometimes filling it almost completely, a condition which is very 
 difficult to diagnose. In the lower jaw they are found in the body 
 of the mandible as well as in the ramus. Radicular cysts sometimes 
 have apparently no connection with a tooth root. In such cases the 
 
 Fig. 760 
 
 guilty tooth may have been extracted, the cyst having escaped notice 
 at the time, or there may have been left in the jaw an epitheliated 
 granuloma, which developed into a cyst later. 
 
 Just how long cysts remain unnoticed depends a great deal on their 
 location and rapidity of growth and upon accidental changes in the 
 pathologic development. Symptoms may appear as changes in the 
 facial contour, such as swellings on the cheek or side of the mandible, 
 on the hard palate or under the lip. Distention of the cyst is often 
 evidenced by indefinable obscure pressure and occasionally causes 
 displacement of some of the teeth. Pain is extremely rare, but in 
 two cases I have seen complete paresthesia of the lower lip, due to 
 
758 ROENTGEN DIAGNOSIS IN OPERATIVE DENTISTRY 
 
 Fig. 761 
 
SPECIAL ROENTGEN STUDY OF DENTAL DISEASES 759 
 
 involvement of the inferior alveolar nerve, A cyst with an opening 
 into the mouth is noticed by the discharge of its excretion, which 
 causes a bad taste and a disagreeable odor in the mouth. Secondary 
 infection, which occurs through the diseased pulp canal or pus pocket 
 of an adjacent tooth frequently causes symptoms of acute or sub- 
 acute dental abscesses and, subsiding, may leave a fistula on the 
 gum, which often leads to faulty treatment. 
 
 The diagnosis of a cyst is easily made by means of the roentgen 
 ray. The roentgen examination should be made on large films or 
 plates, as the small ones seldom cover more than part of the lesion. 
 The cyst cavity appears as a black area on the negative, because it 
 decreases the resistance which in normal bone conditions is put in 
 the way of the rays. The bone immediately surrounding the cavity, 
 however, is usually cortical and dense and so we find the typical 
 picture of a cyst showing a light, but distinct, surrounding line, well 
 illustrated in Figs. 758, 759 and 762. In case of cysts the roentgen 
 picture is also an aid in making a differential diagnosis as well as to 
 give exact information regarding the shape, size and location of the 
 lesion. It shows its relation to important neighboring structures, such 
 as the inferior alveolar nerve, the maxillary sinus and the nose. It 
 will show the number of teeth involved and be a valuable guide for 
 the operative technic. 
 
INDEX. 
 
 Abnormal dentition, diagnosis of, 705 
 Abscess, pericemental, 573 
 Alloys for amalgam See Amalgam, 
 for plates and solders. See Gold, 
 of gold, 347-349 
 Alveolectomy, external, 642 
 
 modified, 643 
 Amalgam, 349 
 
 annealing of, 363 
 buying of, 377 
 chemical relations of, 375 
 classes of, 353-354 
 classification of, 377 
 composition of, 352-360, 361 
 contraction of, 356-363 
 copper, 375 
 
 expansion of, 356-363, 365 
 fillings of, 241 
 flow of, 372 
 keeping of, 377 
 manipulation of, 379-386 
 nature of, 349 
 pluggers for, 245 
 preparation of cavity for, 241 
 properties of, 349 
 strength of, 355, 366 
 thermal relations of, 375 
 washing of, 374 
 Anatomy, surgical, 588, 589 
 
 of teeth, 24-39 
 Anemia, 502 
 
 Anesthesia for dentin, 522 
 injection for, 514 
 
 at incisive foramen, 518 
 
 at infra-orbital foramen, 516 
 
 at mandibular foramen, 519 
 
 at maxillary tuberosity, 517 
 
 at mental foramen, 521 
 
 at posterior palatine foramen, 
 
 518 
 subperiosteal, 514 
 local, 498 
 
 agents for, 503-510 
 areas anesthetized, 517-526 
 armamentarium for, 510 
 conduction, 499-514 
 for operations other than ex- 
 tractions and pulp removal, 
 524 
 history of, 498 
 
 Anesthesia, local, means of producing, 
 499 
 physiologic action of, 500 
 places for injection, 517-526 
 for pulps of teeth, 521 
 technic of, 514 
 terminal, 499-514 
 for pulp, 521-524 
 
 injections for, 521 
 Anesthetics for sensitive dentin, 463 
 Angina, Vincent'^, 575 
 Annealing of alloys, 363 
 
 of gold, 343 
 Antisepsis in root-canal operations. 442 
 Antiseptic cements. See Copper oxy- 
 
 phosphates. 
 Antiseptics, 177 
 Apical foramen, filling of, 445 
 Apicoectomy, 646 
 
 indications and contra-indications 
 
 for, 646 
 technic of, 649 
 Arches, dental, relationships of, 55-57 
 
 shapes of, 53 
 Arthritis, 125 
 Articulation of teeth, 23 
 Atmospheric pressure, occlusion of teeth 
 
 and, 667 
 Atrophy, senile, 580 
 
 of teeth, 23 
 Attachments for bridges, 284-298 
 Auto -intoxication, 551 
 
 B 
 
 Bacteria, 547 
 Bicuspids, canals of, 444 
 
 extraction of, 596, 603 
 Bleaching of teeth, 473 
 
 cataphoresis in, 490 
 
 chlorine in, 475 
 
 dioxid of hydrogen in, 475 
 of sodium in, 475 
 
 Harlan's method of, 487 
 
 iodine in, 475 
 
 light in, 493 
 
 McQuillan's method of, 487 
 
 sulfur dioxid in, 475 
 
 Truman's method of, 480 
 Bloodvessels of peridental membrane, 117 
 of pulp, 92-93 
 
 (761) 
 
762 
 
 INDEX 
 
 Bridge attachments, 284-298 
 
 preparation of cavities for, 284- 
 298 
 Brushes, tooth, 171 
 
 how to use, 173-174 
 Burnishers, 316, 317, 319 
 Burs, 183 
 
 fissure, 183 
 inverted cones, 183 
 l^ound, 183 
 tapered, 183 
 
 Calcification of teeth. See An atomy of. 
 Calcuh, 153-154, 545 
 diagnosis of, 678 
 Canals, root, preparation and filHng of, 
 431-453 
 , treatment of, 411 
 Canines, anatomy of deciduous series, 54 
 
 of permanent series, 28, 42 
 Caries, diagnosis of, 717 
 prevention of, 134 
 susceptibility to, 188 
 Casting of gold inlays, 278-281 
 Cataphoresis in bleaching of teeth, 490 
 Cavities, classification of, 196 
 
 class I, preparation and filling 
 of, 198 
 
 II, preparation and filling 
 of, 204 
 
 III, preparation and filling 
 of, 210 
 
 IV, preparation and filling 
 of, 213 
 
 V, preparation and filling 
 of, 217 
 
 filling of, 164. 
 
 preparation of, instruments for, 182 
 for porcelain inlays, instruments 
 
 for, 300 
 system of, 187 
 
 for amalgam, 241 
 
 for bridge attachments, 
 
 284-298 
 for cements, 252 
 for gold foil, 187-218 
 
 inlays, 261-284 
 for gutta percha, 249 
 for porcelain inlays, 299 
 tapered, 284-298 
 Cell activity, occlusion of teeth and, 664 
 Cement, fillings of, 252 
 Cementation of gold inlays, 282 
 of porcelain inlays, 334-338 
 Cementoblasts, 106 
 Cements 386 
 
 copper oxy phosphates, 390 
 germicidal. See Copper oxyphos- 
 
 phates. 
 mixing of, 400 
 preparation of cavities for, 252 
 
 Cements, properties of, 386 , 396-400 
 
 silicate, 252, 254, 338, 395 
 
 silver. See Copper oxj^hosphates. 
 
 zinc oxyphosphates, 387-388 
 Cementum, exostosis of, 98 
 
 formation of, 96 
 
 fimction of, 95 
 
 hypertrophies of, 98 
 
 nature of, 95 
 
 structure of, 96-97 
 Charts, roentgenogram, 495 
 Chemicals for root-canal treatment, 411- 
 
 414 
 Children's teeth, filling of, 255-312 
 Chlorapercha, 449 
 Chlorine in bleaching of teeth, 475 
 
 use of, in root canals, 416 
 Clamps, rubber dam, 187-217 
 Cocaine, 506 
 
 Concretions, removal of, 153 
 Conduction anesthesia, 499-514 
 Conductivity of gold, 346 
 Contact, proximate, 165 
 Contours, 165 
 
 Contraction of amalgam, 356-363 
 Copper amalgam, 375 
 
 oxyphosphates, 390 
 
 liquid portion See Zinc oxy- 
 phosphates. 
 powder portion, 390 
 Cresol-formalin, use of, in root canals, 415 
 Cuspids, canals of, 444 
 
 extraction of, 595, 603 
 Cysts, diagnosis of, 713-756 
 
 Deciduous teeth, 23, 54 
 extraction of, 606 
 filling of, 255 
 Deglutition, occlusion of teeth and, 666 
 Dental floss, 175 
 Dentifrices, 175 
 Dentin, 81 
 
 anesthesia for, 522 
 
 composition of, 81 
 
 derivation of, 81 
 
 granular layer of Tomes, 85, 88, 89, 
 
 97 
 hypersensitive, 454 
 pathology of, 454 
 symptoms of, 458 
 treatment of, 458 
 innervation of, 454 
 interglobular spaces of, 86 
 junction of, with enamel, 86 
 matrix of, 82 
 structural elements of, 82 
 tubuli of, 82-91 
 direction of, 84 
 Dentistry, operative, description of, 179 
 preventive, description of, 122-127 
 
INDEX 
 
 763 
 
 Dentition, abnormal, diagnosis of, 705 
 Devitalized teeth, 698 
 
 retention of, 699 
 Diabetes mellitus, 550 
 Diagnosis. See Roentgen diagnosis. 
 Dichloramin-T, use of, in root canals, 416 
 Diets, 141 
 
 Dioxid of hydrogen in bleaching of teeth, 
 475 
 of sodium in bleaching of teeth, 475 
 Disclosing solution, 161 
 Discoloration of teeth, 467 
 
 causes of, 467 
 
 rationale of process, 469 
 
 special, 495 
 
 treatment of, 467 
 
 which can be removed, 473 
 Ductility of gold, 341 ■ 
 
 E 
 
 Electrolysis, use of, in root canals, 419- 
 422 
 
 Enamel margins, 195 
 of teeth, 63 
 
 cementing substance of, 65 
 cleavage of, 69 
 composition of, 64 
 derivation of, 63 
 incremental lines of, 74 
 rods of, 65 
 
 direction of, 72, 194 
 stratification bands of, 73 
 strength of, requirements for, 75 
 structural element of, 65 
 
 Endocarditis, 125 
 
 Endosmosis, electric, for sensitive den- 
 tin, 464 
 
 Ethyl chlorid, 503 
 
 Eucapercha, 261 
 
 Exostosis, 98 
 
 Expansion of amalgam, 356-363, 365 
 of gold, 344 
 
 Expression, occlusion of teeth and, 667 
 
 Extension for prevention, 137, 188 
 
 Extirpation of pulps of teeth, 723 
 
 Extraction of teeth, 588-642 
 accidents during, 621 
 bicuspids, 596, 603 
 contra-indications for, 591 
 cuspids, 595, 603 
 deciduous, 606 
 hemorrhage following, 626 
 impacted, 630, 637 
 incisors, 593, 594, 602 
 indications for, 591 
 instruments for, 608-641 
 management of patient for, 592 
 molars, 598-600, 604, 637 
 pathology involved in, 634 
 post-operative pains in, 629 
 
 treatment in, 628-640 
 pre-operative treatment in, 628 
 
 Extraction of teeth, roots, 607 
 supernumerary, 607 
 unerupted, 630, 637 
 
 Files for finishing, 238 
 Filling of apical foramen, 445 
 
 materials, properties of, 339 
 
 of pulp chambers, zinc oxychlorid 
 
 for, 482 
 of root canals, 431-453 
 Fillings of amalgam, 241 
 of cement, 252 
 finishing of, 237 
 of gold, 218 
 of gutta-percha, 249 
 of inlays, 261-299 
 radiolucency of, 719 
 Fihns, 160 
 
 for roentgenograms, 679-683 
 development of, 684 
 Finishing fillings, 237 
 files for, 238 
 of gold inlays, 281 
 knives for, 238 
 saw for, 238 
 strips for, 240 
 Fissure burs, 183 
 Floss, dental, 175 
 Forms of teeth, diversities in, 22 
 Formula for alloys for amalgam. See 
 Amalgam, 
 for plates and solders. See Gold. 
 Furnaces, 329 
 Fusing of porcelain inlays, 317-326 
 
 G 
 
 Germicidal cements. See Copper oxy- 
 
 phosphates. 
 Gingivitis, ulcerative, 582 
 Glycogen in saUva, 140 
 Gold, 339 
 
 alloys of, 347-349 
 
 conductivity of, 346 
 
 ductility of, 341 
 
 expansion of, 344 
 
 fillings of, 218 
 
 foil, preparations of cavities for, 187- 
 
 218 
 hardness of, 342 
 inlays, 261 
 
 as bridge attachments, 284-298 
 casting of, 278-281 
 cavities for, 262-270 
 
 conflicting opinions con- 
 cerning, 284-298 
 preparation of, 261-284 
 cementation of, 282 
 finishing of, 281 
 gold for, 289 
 
764 
 
 INDEX 
 
 Gold inlays, indirect method for, 283- 
 321, 323 
 pattern for, 271 
 
 investing of, 274 
 removal of, 277 
 
 malleability of, 342 
 
 melting-point of, 340 
 
 oxidation of, 346 
 
 pluggersfor, 231-233 
 
 preparation of, for fillings, 218 
 
 properties of, 339 
 
 solubility of, 346 
 
 specific gravity of, 340 
 
 tensile strength of, 344 
 
 volatiHty of, 341 
 Granular layer of Tomes, 85, 88, 89, 97 
 Gums, retraction of, 579 
 Gutta-percha, 401, 449 
 
 employment of, 404 
 
 fillings of, 249 
 
 preparation of cavities for, 249 
 
 properties of, 401, 403 
 
 radiolucency of, 719 
 
 with other materials, 410 
 
 H 
 
 Hardness of gold, 342 
 
 Harlan's method of bleaching teeth, 487 
 
 Haversian canals, 117 
 
 Hemorrhage following extraction of 
 
 teeth, 626 
 High-pressure syringes, 523 
 Histology of teeth, 59 
 Hunter's "Anathematization of Ameri- 
 can Dentistry," 123 
 Hygiene movement, oral, 138 
 Hypersensitive dentin, 454 
 
 pathology of, 454 
 
 symptoms of, 458 
 
 treatment of, 458 
 Hypertrophy, 98 
 Hypodermic syringes, 511, 512 
 
 Impacted teeth, diagnosis of, 710 
 
 extraction of, 630, 637 
 Incisive foramen, injection at, for anes- 
 thesia, 518 
 Incisors, anatomy of deciduous series, 54 
 of permanent series, 24, 39 
 canals of, 444 
 
 extraction of, 593, 594, 602 
 Infection, diagnosis of, 137, 743, 749 
 Infra-orbital foramen, injection at, for 
 
 anesthesia, 516 
 Injection for anesthesia, 514 
 
 at infra-orbital foramen, 516 
 at incisive foramen, 518 
 at mandibular foramen, 519 
 at maxiUary tuberosity, 517 
 
 Injection for anesthesia at mental fora- 
 men, 521 
 for other operations thanextrac- 
 
 tions and pulp removal, 524 
 at posterior palatine foramen, 
 
 518 
 of pulp, 521 
 subperiosteal, 514 
 Inlays, fimngs of, 261, 299 
 gold, 261 
 
 as bridge attachments, 284-298 
 casting of, 278-281 
 cavities for, 262-270 
 
 conflicting opinions con- 
 cerning, 284-298 
 cementation of, 282 
 finishing of, 281 
 gold for, 289 
 indirect method for, 283, 321- 
 
 323 
 pattern for, 271 
 
 investing of, 274 
 removal of, 277 
 porcelain, 299 
 
 cavities for, 299-314, 336 
 
 preparation of, instruments 
 for, 300 
 cementation of, 334-338 
 colors of, 332 
 furnaces for, 329 
 fusing of, 317-326 
 indirect method for, 321 
 matrix for, 314-323 
 shading of, 333 
 Instruments for cavity preparation, 182 
 chisels, 182 
 hatchets, 182 
 hoes, 182 
 
 trimmers, marginal, 182 
 for extraction of teeth, 608-641 
 for fillings, 231, 233, 245 
 for finishing fillings 237-258 
 plastic, 250 
 sharpening of, 184 
 sterilization of, 431, 511, 514 
 Intestinal intoxication, 552 
 Intoxication, auto-, 551 
 
 intestinal, 552 
 Iodine in bleaching of teeth, 474 
 
 Knive6 for finishing, 238 
 
 Light in bleaching of teeth, 493 
 
 Local anesthesia, 498. See Anesthesia, 
 
 local. 
 Lymphatic system of teeth, 58 
 Lymphatics of peridental membrane, 119 
 of pulp, 92-93 
 
INDEX 
 
 765 
 
 M 
 
 McQuillan's method of bleaching teeth, 
 
 487 
 Malleabihty of gold, 342 
 Mal-occlusion of teeth, 668 
 etiology of, 668 
 treatment for, 670 
 
 appliances and technic for 
 
 673 
 retention, 674 
 time of, 670 
 Mandibular foramen, injection at, for 
 
 anesthesia, 519 
 Mastication, occlusion of teeth and, 666 
 Matrix, use of, 242-248 
 Maxillary sinuses, diseases of, diagnosis 
 of, 701 
 tuberosity, injection at, for anes- 
 thesia, 517 
 Melting-point of gold, 340 
 Mental foramen, injection at, for anes- 
 thesia, 521 
 Mercury, 380 
 Mixing cements, 400 
 Molars, anatomy of deciduous series, 54 
 of permanent series, 34, 46 
 
 f>Q rj o 1 c of A.A.A. 
 
 extraction of, 598-600, 604, 637 
 Morphology of teeth, 21 
 Muscular action, occlusion of teeth and, 
 
 665 
 Myocarditis, 125 
 
 N 
 
 Necrosis, diagnosis of, 731 
 
 Nerve tissue of peridental m.embrane, 
 
 117-120 
 Nervous system of teeth, 57 
 Neuralgia, diagnosis of, 703 
 Nitro-hydrochloric acid, use of, in root 
 
 canals, 413 
 Novocaine, 509 
 
 O 
 
 Occlusion of teeth, 653 
 
 development of, 655-656 
 forces governing, 663 
 
 atmospheric pressure, 
 
 667 
 attention and muscu- 
 lar tone, 667 
 cell activity, 664 
 deglutition, 666 
 expression, 667 
 mastication, 666 
 muscular action, 665 
 respiration, 666 
 nomenclature and classification, 
 
 668 
 normal, 654 
 
 Occlusion of teeth, traumatic, 544 
 Odontoblasts, 89-90. *S'ee also Teeth. 
 Operative dentistry, description of, 179 
 Oral hygiene movement, 138 
 prophylaxis, 139-151 
 sepsis, 127 
 Orthodontia, principles of, 653. See also 
 
 Occlusion. 
 Osteoclasts, 109 
 Osteomyelitis, diagnosis of, 753 
 Ostitis, diagnosis of, 756 
 Oxidation of gold, 346 
 Oxyphosphates of copper, 390 
 liquid portion, 387 
 powder portion, 390 
 of zinc, 387-388 
 
 liquid portion, 387 
 powder portion, 388-389 
 
 Pain, cause of, 456 
 
 post-operative, 629 
 
 Palatine foramen, posterior, injection at, 
 for anesthesia, 518 
 
 Paste polisher, 162 
 
 Patient, instructions to, 170 
 
 Pericemental abscess, 573 
 
 Pericementum, 98 
 
 Peridental affections, 133 
 membrane, 98 
 
 arrangement of, 99-103 
 bloodvessels of, 117 
 cellular elements of, 105 
 cementoblasts of, 106 
 changes in , with age, 121 
 epithelial structure of, 112-115 
 functions of, 98 
 giant cells of, 98 
 IjTuphatics of, 119 
 nerves of, 117-120 
 osteoclasts of, 109 
 structural elements of, 98 
 
 Permanent teeth, 23, 24 
 
 Pigments, source of, 467 
 
 Planing instruments, 159 
 
 Plaques, 160 
 
 Pluggers for amalgam, 245 
 for gold, 231-233 
 
 Pneumococci, 125, 669 
 
 Pockets, pyorrheal, 169 
 
 Poisons, systemic, 550 
 
 Polishing cups, 162 
 
 teeth and fillings, 161 
 
 Porcelain inlays, 299 
 
 cavities for, 299-314, 336 
 preparation of, 299 
 
 instruments for, 300 
 cementation of, 334-338 
 colors of, 332 
 furnaces for, 329 
 fusing of, 317-326 
 indirect method for, 321 
 
766 
 
 INDEX 
 
 Porcelain inlays, matrix for, 314-323 
 
 shading of, 333 
 Potassium sodium, use of, in root canals, 
 
 412 
 Preventive dentistry, description of, 122, 
 
 127 
 Prophylaxis, oral, 139-151 
 Pulp, anesthesia for, 521-524 
 
 canals, disease of, diagnosis of, 727, 
 
 730, 731 
 cavities of teeth, 52, 53 
 chambers, filling of, zinc oxychlorid 
 
 for, 482 
 of teeth, bloodvessels of, 92-93 
 derivation of, 89 
 enervation of, 94 
 extirpation of, 723 
 function of, 94 
 layer of Weil of, 92 
 lymphatics of, 92-93 
 membrana eboris of, 89 
 nerve tissue of, 94 
 odontoblasts of, 89, 90 
 structure of, 89 
 sensory, 95 
 Pus, 559 
 Pyorrhea alveolaris, 527 
 
 cause of, 534-542 
 definition of term, 527 
 diagnosis of, 554, 751 
 general principles of, 537 
 healed lesions of, 582 
 history of, 527-534 
 operative procedures for, 536 
 prevention of, 149 
 pockets of, 169 
 treatment of, 561 
 
 R 
 
 Radiolucency of fillings, 719 
 
 of gutta-percha, 719 
 Records for root-canal work, 451 
 Respiration, occlusion of teeth and, 666 
 Retraction of gums, 579 
 Roentgen diagnosis, 675 
 
 in abnormal dentition, 705 
 
 of abscesses or granulomata, 740 
 
 of bone repair, 747 
 
 of caries, 717 
 
 of cysts, 713-756 _ 
 
 in diseases of maxillary sinuses, 
 701 
 of pulp canals, 727, 730, 731 
 
 for impacted and unerupted 
 teeth, 710 
 
 nomenclature of, 675 
 
 of osteomyelitis, 753 
 
 of ostitis, 756 
 
 of pulps of teeth, 723-727 
 
 of pyorrhea alveolaris, 751 
 
 in root canal fillings, 736 
 
 in somatic disease, 698 
 
 Roentgen diagnosis for supernumerary 
 teeth, 712 
 for trifacial neuralgia, 703 
 Roentgenogram, 675 
 angle of rays, 679 
 exposure for, 683 
 development of films, 684 
 interpretation of, 688 
 mounting of, 695 
 production of rays, 676 
 recording of, 695 
 tubes for, 677 
 
 use of, in root-canal work, 446 
 Roentgenology, 675 
 Root canals, 431 
 
 preparation and filling, 431-453 
 
 equipment for, 431-442 
 treatment of, 411 
 chemical, 411 
 electric, 419-430 
 therapeutic, 414 
 fillings, making of. See Root canals, 
 removal of, 451 
 Roots of teeth, arrangement of, 52, 53 
 
 extraction of, 607 
 Round burs, 183 
 
 Rubber dam, application of, 185, 443 
 clamps, 187, 217 
 
 Saliva, glycogen in, 140 
 
 sulphocyanate in, 140 
 Saw for finishing, 238 
 Scalers, 156, 157, 158 
 Sedatives for sensitive dentin, 463 
 Senile atrophy, 580 
 Separators, 210 
 Sepsis, oral, 127 
 Shading of inlays, 333 
 Silicate cements, 395 
 Silver cements. See Copper oxyphos- 
 
 phates. 
 Solubility of gold, 346 
 Specific gravity of gold, 340 
 Stains, 160 
 
 Staphylococci, 125, 669 
 Sterilization of instruments, 431, 511-514 
 
 of root canals, 411, 414, 427 
 Streptococci, 125 
 Stresses, amount of, in mastication, 180 
 
 relief of, 168 
 Subperiosteal injection for anesthesia, 5 14 
 Sulci, protection of, 170 
 Sulfur dioxid in bleaching of teeth, 475 
 Sulphocyanate in saliva, 140 
 Sulphuric acid, use of, in root canals, 413 
 Supernumerary teeth, diagnosis of, 712 
 
 extraction of, 607 
 Suprarenal capsule, 504 
 Surgeon's knot, 187 
 Surgery, 558 
 
 extraction of teeth, 558-642 
 
INDEX 
 
 767 
 
 Surgery, other surgical procedures, 642- 
 
 652 
 Syringes, high-pressure, 523 
 hypodermic, 511, 512 
 
 Tapered burs, 183 
 Teeth, 17 
 
 anatomy of deciduous, 54 
 calcification of, 55 
 canines, 54 
 incisors, 54 
 molars, first, 54 
 second, 54 
 occlusal surfaces of, 55 
 permanent, mandibular, 39 
 canines, 42 
 incisors, first, 43 
 
 second, 45 
 molars, first, 46 
 second, 49 
 third, 50 
 premolars, first, 43 
 second, 45 
 maxillary, 24 
 canines, 28 
 incisors, first, 24 
 
 second, 26 
 molars, first, 34 
 second, 36 
 third, 38 
 premolars, first, 30 
 second, 32 
 arches of, dental, shape of, 53 
 articulation of, 23 
 atrophy of, with age, 23 
 bleaching of, 473 
 
 cataphoresis in, 490 
 
 chlorine in, 475 
 
 dioxid of hydrogen in, 475 
 
 of sodium in, 475 
 Harlan's method of, 487 
 iodine in, 475 
 
 McQuillan's method of, 487 
 sulfur dioxid in, 475 
 Truman's method of, 480 
 calcification of. See Anatomy of. 
 canines, 19 
 
 mandibular, 19 
 maxillary, 19 
 cementum of, exostosis of, 98 
 formation of, 96 
 function of, 95 
 hypertrophies of, 98 
 nature of, 95 
 structure of, 96-97 
 dentin of, composition of, 81 
 
 granular layer of Tomes, 85, 88, 
 
 89, 97 
 interglobular spaces of, 86 
 junction of, with enamel, 86 
 matrix of, 82 
 
 Teeth, dentin of, structural elements of, 
 82 
 tubuli of, 82-91 
 
 direction of, 84 
 devitahzed, 698 
 
 retention of, 699 
 discoloration of, 467 
 causes of, 467 
 rationale of process, 469 
 special; 495 
 treatment of, 467 
 which can be removed, 473 
 diversities in shape of, 22 
 enamel of, cementing substance of, 
 65 
 cleavage of, 69 
 composition of, 64 
 derivation of, 63 
 incremental lines of, 74 
 rods of, 65 
 
 direction of, 72 
 stratification bands of, 73 
 strength of, requirements for, 75 
 structural elements of, 65 
 extraction of, 588-642 
 accidents during, 621 
 bicuspids, 596, 603 
 contra-indications for, 591 
 cuspids, 595, 603 
 deciduous, 606 
 hemorrhage following, 626 
 impacted, 630, 637 
 incisors, 593, 594, 602 
 indications for, 589 
 instruments for, 608-641 
 management of patient for, 592 
 molars, 598-600, 604, 637 
 pathology involved in, 634 
 post-operative pains in, 629 
 
 treatment in, 628, 640 
 pre-operative treatment in, 628 
 roots, 607 
 
 supernumerary, 607 
 unerupted, 630, 637 
 genesis of, 59 
 histology of, 59 
 impacted, diagnosis of, 710 
 extraction of, 630, 637 
 incisors, first and second, 18 
 
 central and lateral, 18 
 mandibular, 18 
 maxillary, 18 
 lymphatic system of, 58 
 mal-occlusion of, 668 
 etiology of, 668 
 treatment of, 670 
 
 appliances and technic for, 
 
 673 
 retention, 674 
 time of, 670 
 mammalian formula of, 20 
 molars, first, second, third, 20 
 deciduous, 20 
 permanent, 20 
 
768 
 
 INDEX 
 
 Teeth, morphology of, 21 
 nervous system of, 57 
 occlusion of, 653 
 
 classification of, 668 
 development of, 655 
 forces governing, 663 
 
 atmospheric pressure, 
 
 667 
 attention, 667 
 cell activity, 664 
 deglutition, 666 
 expression, 667 
 mastication, 666 
 muscular action, 665 
 
 tone, 667 
 respiration, 666 
 nomenclature of, 668 
 normal, 654 
 peridental membrane of, 98 
 
 arrangement of, 99-103 
 bloodvessels of, 117 
 cellular elements of, 105 
 cementoblasts of, 106 
 changes in, with age, 121 
 epithelial structures of, 
 
 112-115 
 functions of, 98 
 giant cells of, 98 
 lymphatics of, 119 
 nerves of, 117-120 
 osteoclasts of, 109 
 structural elements of, 98 
 premolars, first and second, 19 
 
 known as bicuspids, 19 
 mandibular, 20 
 pulp of, bloodvessels of, 92-93 
 cavities of, 52-53 
 enervation of, 94 
 extirpation of, 723 
 function of, 94 
 sensory, 95 
 layer of Weil of, 92 
 lymphatics of, 92-93 
 membrana eboris of, 89 
 nerve tissue of, 94 
 odontoblasts of, 89, 90 
 structure of, 89 
 roots of, arrangement of, 52-53 
 succession of, 23 
 
 deciduous or milk, 23 
 permanent, 23 
 
 Teeth, supernumerary, diagnosis of, 712 
 extraction of, 607 
 
 types of, 166 
 
 unerupted, diagnosis of, 710 
 extraction of, 630, 637 
 
 vascular system of, 57 
 Tensile strength of gold, 344 
 Terminal anestliesia, 499-514 
 Therapeutics of root-canal treatment,414 
 Tomes, granular layer of, 85, 88, 89, 97 
 Tooth brushes, 171 
 
 how to use, 173-174 
 Traumatic occlusion, 544 
 Traumatism, 580-543 
 
 diagnosis of, 716 
 Trifacial analysis, diagnosis of, 703 
 Truman's method of bleaching teeth, 480 
 Tubuli of dentin, 82, 91. See also Teeth. 
 
 U 
 
 Ulcerative gingivitis, 582 
 Unerupted teeth, diagnosis of, 710 
 extraction of, 630, 637 
 
 Vascular system of teeth, 57 
 Vincent's angina, 575 
 Volatility of gold , 341 
 
 W 
 
 Wadelstaedt tie, 187 
 
 X-RAYS. See Roentgenogram. 
 
 Zinc oxychlorid for filling pulp cham- 
 bers, 482 
 oxyphosphates, 387-388 
 liquid portion, 387 
 powder portion, 388-389 
 
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