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CROWN AND BRIDGE-WORK 
 
 FOR STUDENTS AIS^D PRACTITIONERS 
 
 BY 
 
 FREDERIC A. PEESO, D.D.S. 
 
 UIRLCTOlt OF THE DENTAL GKADUATE SCHOOL OF THE UNIVERSITY OF PENNSYLVANIA, 
 
 PHILADELPHIA 
 
 lllugtratcD wltb 732 cnaravinas 
 
 LEA & FEIM(4EI{ 
 
 J'H i l,.\ I)I;M'II I A AND N i; W ^()|{K 
 
 I •» 1 (i 
 
a.- 
 
 Entered according to the Act of Congress, in the year 1916, by 
 
 LEA & FEBIGER, 
 in the Office of the Librarian of Congress. AH rights reserved. 
 
TO MY BEST 
 FRIEND AND COLLEAGUE 
 
 ARCHIBALD C. EGLIN, D.D.S. 
 
 IN GRATEFUL RECOGNITION AND REMEMBRANCE 
 
 OF THE STIMULUS AND INSPIRATION 
 
 RECEIVED FROM HIM 
 
 THIS VOLUME IS RESPECTFULLY 
 
 DEDICATED 
 
PREFACE. 
 
 The technic of Oowu and Bridge-work has assumed far more 
 importanee since dentists and physicians have reahzed the close 
 rehition of oral cleanliness to the patient's physical Avell-being 
 To secure a full measure of stability with promise of long service, 
 with the restoration of function in mastication and speech, was 
 once considered the aim and end of successful Crown and Bridge- 
 work. 
 
 Though all careful dentists appreciate the importance of accurate 
 workmansliip in attaining these desirable results, and that these 
 ])rostlietic appliances should be so designed as to facilitate clean- 
 liness, the announcement that some cases of Crown and Bridge-work 
 which had fulfilled all mechanical requirements had, nevertheless, 
 proved a serious menace to the health of the patient, came as a 
 rude shock to the dental profession. 
 
 Errors in judgment or workmanship in repairing injuries to the 
 natural organs, or in treating their many pathological conditions, 
 are usually local, and are readily seen. Recently, attention has 
 been directed to the possibility of serious, even fatal, ])athol<)gical 
 lesions arising from unseen and unrecognized conditions developed 
 under Crown and Bridge constructions which had been worn with 
 comfort and satisfaction, aiul apparent!}' were well designed and 
 well made. That they were the cause of the trouble in the un- 
 fortunate cases reported was reached only by a process of excluding 
 otiicr probable causes. The proof was furnished by the conditions 
 revealed on their removal and the rapid and c()nij)letc recovery 
 which followed. 
 
 This has prompted the writer to give special attention to this 
 aspect of the subject. The troul)le justly complained of is not 
 iiilHTcnt in Crown and Bridge-work construction itself — it is due 
 entirely to errors of judgment in the selection or i)reparation of 
 supports or abutments, and .'ivoidabN- errors in designing an<i 
 constructing tlic ajjpliances. 
 
vi PREFACE 
 
 The writer desires to enforce the most exacting care in all pre- 
 paratory procedures to ensure a healthy condition of the supports 
 and abutments, and thoroughness in the mechanical preparation 
 for all attachments. If these are accurately fitted, and are strong 
 enough for the work demanded of them, and the requirements of 
 occlusion are fully met, he feels assured that the appliances will 
 prove aseptic, durable, and efficient. 
 
 In formulating and presenting to the profession the methods 
 found satisfactory in practice in the preparation for and con- 
 struction of Crown and Bridge-work, he has borne in mind the 
 paramount importance of a well-considered aseptic technic in 
 addition to that required to meet the mechanical problems 
 involved. 
 
 A long experience in private practice and in the teaching of 
 this dental specialty has enabled him to select and present 
 methods readily acquired, that produce results quickly and with 
 certainty, if carefully followed. He would add, however, the 
 caution that it requires long and patient practice to thoroughly 
 master the details of operations which, although common to the 
 dental workroom, when applied to Crown and Bridge- work are 
 more exacting, and call for a more skilful use of tools and 
 appliances than when used in constructing ordinary plate work. 
 
 The author cannot conclude without expressing his apprecia- 
 tion of the assistance given by Dr. Wm. H. Trueman, and especi- 
 ally Dr. Edward C. Kirk and Dr. A. C. Eglin, whose inspiration, 
 constant interest and encouragement for several years past have 
 been largely responsible for the production of this volume. 
 
 He also wishes to express his gratitude to Mr. Christian 
 Febiger, whose patience, courtesy and many kindnesses have done 
 so much to lighten the work. 
 
 F. A. P. 
 
 New York, 1916. 
 
COIs TENTS. 
 
 CHAPTER I. 
 Artificial C'uowns .• • ^' 
 
 CHAPTER II. 
 
 P\THOIOGir\L CoN'OtTIOXS IN THEIU RELATION TO CrOWM AND 
 
 22 
 Bridge-work 
 
 CHAPTER III. 
 
 Crown and Bridge-work in Relation to the Vitality of the Pulps 
 
 IN Supporting Teeth ' '^•^ 
 
 The Pulp C> 
 
 CHAPTER IV. 
 
 ..... 40 
 
 CHAPTER V. 
 
 Relative Strength of the Teeth as Supports for Bridge-work 72 
 
 CHAPTER VI. 
 
 Typical Shapes of the Teeth. Mechanical Preparation of the 
 
 Teeth AND Roots for THE Reception OF THE Bands .... 78 
 
 Impressions and Models 
 
 CHAPTER VII. 
 
 . . . 120 
 
 CI I A ITER VIII. 
 
 li, iLDi.NG IP Broken-down R<.ots with Amai^ciam Puhpakatouy to ^^^ 
 Crowning 
 
 CIIAI'TIIH IX. 
 
 . , . \r,{) 
 
 Prostmesls 
 
viii CONTENTS' 
 
 CHAPTER X. 
 The Making of the Crowns 187 
 
 CHAPTER XI. 
 Bridge-work 205 
 
 CHAPTER XII. 
 Removable Bridge-work -. 225 
 
 CHAPTER Xni. 
 Tubes and Split Pins 276 
 
 CHAPTER XIV. 
 
 Methods of Using Porcelain Crowns with Cast Bases in 
 
 Removable Bridge-work 301 
 
 CHAPTER XV. 
 Retaining Media 336 
 
 CHAPTER XVI. 
 Repairing Crowns and Replacing Broken Facings 342 
 
 CHAPTER XVII. 
 
 By Howard T. Stewart, D.D.S. 
 
 Bridge-work Designed for Rigg's Disease Conditions . . . . 351 
 
 CHAPTER XVIII. 
 
 By Louis J. Weinstein. 
 
 Dental Metallurgy 357 
 
 CHAPTER XIX. 
 By Fred'k K. Ream, M.D., D.D.S., 
 
 AND 
 
 Richard H. Riethmuller, Ph.D., D.D.S. 
 
 The Uses and the Value of Radiography in Crown and 
 
 Bridge-work 408 
 
INTKOnUCTlON. 
 
 Although crown and bridge-work has come down to us from 
 remote antiquity, it is only within the hist three or four decades 
 that it has assume<l an imi)ortant place in dental prosthetics. In 
 the beginnino; of this revival, most of the work was done in a hap- 
 hazard way, with but little or no understanding of the principles 
 involved, and with but little api)reciation of its requirements, its 
 possibilities, or its dangers. 
 
 The sole idea of the dental practitioner was to give the patient 
 something better than the i)artial plates then in use, something 
 resembling more closely the lost natural teetli in firmness and in 
 abihty to i)erform their normal functions. 
 
 Crude as crown and bridge-work then was, it was sufficiently 
 successful to be appreciated by the community, and to be considered 
 by the profession as promising greater usefulness than the appliances 
 it supplanted. Patients demanded it, and this prompted an earnest 
 effort on the part of many in the profession to discover and remedy 
 its shortcomings. As the result of this, within a few years crown 
 and bridge-work has earned recognition as a specialty- in dental 
 science. 
 
 As often happens when new things are introduced, or old things 
 are so revolutionized that they enter, quickly, upon a higher stage 
 of development, the limitations of crown and bridge-work were 
 but slowly recognized. The importance of firm and healtliN- supports, 
 due consideration of the mechanical principles in designing and 
 construction, careful attention to occlusion, and work that was 
 thoroughly aseptic, received but little thought during the early 
 days of crown and })ridge-work. As a result the work was usuallx 
 short-lived, was not cleanly, and the appliance was not always 
 comfortable or effective. 
 
 Looking back to this period in the development of crown and 
 bridge-work, viewing the monstrosities in.serted by thoughtless 
 enthusiasts as dental bridges, or reading the records of disappoint- 
 ment, failures and disasters, one wonders how the art survixcd. 
 
X INTRODUCTION 
 
 That it did survive is due to the unceasing efforts of a few earnest 
 workers who saw its promising future, and by careful study, step 
 by step, traced failures to their source, and unraveled the principles 
 involved in designing and constructing successful, lasting and 
 asceptic, crown and bridge-work. Though the ideal has not been 
 reached, crown and bridge-work has been placed upon a more 
 secure foundation, and a most promising future is unfolded as the 
 result of these labors. 
 
 That the crown and bridge-work of the early days was faulty 
 was not due entirely to poor workmanship. Many of the early 
 practitioners were especially skilful workmen, and did excellent 
 work. The trouble lay in the science not being sufficiently developed 
 to enable them to work understandingly, especially in the pre- 
 paratory work upon which so much depends. Treatment of patho- 
 logical conditions was not understood and appreciated as it is now. 
 Remedial agents and procedures, now considered indispensable, 
 were then unknown; instruments, appliances and precautionary 
 measures, which have aided so much to make this work effective, 
 were then undreamed of. 
 
 Recognition of the underlying principles or factors which make 
 for or against successful bridge-work came slowly. Prominent 
 among these was root and abutment preparation. In a majority 
 of the early cases, we might perhaps say in all, there was no 
 attempt made to prepare the mouth, scientifically, for the reception 
 of the work. The importance of pulp canal cleansing, thorough 
 treatment of pathological conditions, and effective pulp-canal filling 
 was appreciated by a few only, and these were hampered by de- 
 fective instruments and inability to promptly verify the accuracy 
 of their work. This handicap has since been razed by the intro- 
 duction of delicate pulp-canal instruments and the marvelous 
 x-ray. 
 
 Abutment trimming, so important to properly fitting abutment 
 crowns, was often ignored; indeed, until the introduction of prop- 
 erly shaped abrasive wheels and disks, it was practically impossible. 
 The introduction of these useful instruments was a step only, for 
 until it was demonstrated that a devitalized tooth made as good, or 
 even a better abutment than a vital tooth, the intense pain attend- 
 ing abutment trimming too frequently halted the operation before 
 it was complete. The discovery of pressure anesthesia, and other 
 anesthetic processes, making possible the painless devitalizing of a 
 pulp without injury to the tissues around the apex of the tooth. 
 
INTRODUCTION xi 
 
 was the last step that made possible scientific abutment trimming, 
 and the construction of an aceptic abutment crown. 
 
 Still another fundamental to crown and bridge-work success was 
 brought to the fore when a few scientifically inclined earnest workers, 
 in an eftort to make more effective artificial dentures, began a 
 careful study of the various movements of the mandible during 
 mastication. The object of these eft'orts was to devise a contrivance 
 to accurately reproduce these movements so as to enable the dental 
 workman, when mounting artificial teeth, to secure a more normal 
 occlusion. 
 
 Heretofore, if the upper and lower teeth articulated with each 
 other when the mandible was at rest, the work was deemed satis- 
 factory, notwithstanding that the dentures were quite ineffective 
 in mastication, t)wing to the fact that all the teeth met only when 
 the mandible was in the rest position. At other times but few teeth 
 were in contact. The immediate result of these investigations 
 was a better understanding of the mechanism of mastication, and 
 a higher appreciation of the importance of normal occlusion that 
 has since reached all departments of our profession. By occlusion 
 is understood a rubbing or grinding surface contact of all the 
 masticating surfaces of the teeth, during all the movements of 
 the mandible, as is always the case with the natural teeth in 
 their normal position. Articulation is a mere fitting together in 
 one position only. 
 
 This understanding of occlusion brought to the fore an imper- 
 fectly recognized cause of failure of many dental bridges. With 
 the mouth closed, the teeth on these bridges fitted the o})posing 
 teeth accurately, but during mastication they touched at a few 
 points only. Except for this fact these bridges might have given 
 many years of excellent service, but owing to defective occlusion 
 the force of mastication was concentrated upon a few teeth, which 
 resulted in literally pounding the structure to pieces in a .short 
 time. In other cases the stress set up a destructive irritation in 
 one or more of the supporting abutments, which just as surely 
 resulted in the bridge failing. 
 
 We now know that it is impossible for any one tooth to be niuhilx' 
 strained during mastication, or other movements of the mandible 
 if the occlusion of the denture has been properly adjusted, be it 
 a j^late, a rrowii, or a bri<lgc. 
 
 ('rr)Wiiiiig (»r \ital tcctli |)n)\<'(l to be the cause of iiiiiiicnuis 
 failures, although at one time a \ital abutment was (Iccnicd more 
 
xii INTRODUCTION 
 
 reliable than one devitalized. After a few years many cases, where 
 vital abutments were used, developed dento-alveolar abscesses, the 
 pulp in the meantime having died as the result of irritation, per- 
 haps from denuding of its enamel when preparing the crown for an 
 abutment cap, or perhaps from irritation due to the cement. In 
 other cases an overstimulation of the pulp produced secondary 
 dentin deposits, pulp stones, and other kindred troubles. 
 
 It was quite a step forward when the profession recognized that 
 the pulp was a formative organ, and that when its work was done, 
 it was no longer necessary to the life and health of the tooth. 
 Also when a technic was developed by which the pulp could be 
 removed painlessly and its place occupied by an inert substance, 
 with but little risk, if any, that the tooth would ever become a 
 source of trouble as the result of its devitalization. 
 
 Until within recent years but little thought has been given to the 
 stress of mastication, the force developed by the muscles moving 
 the mandible, and the force required to properly perform the 
 function of mastication. Until this information' was available, 
 designing a bridge to withstand this force year after year was mere 
 guess-work. Too often the stress of mastication and the strength 
 of the bridge or its abutments was grossly underestimated, and 
 failures thereby invited. We now know that ample strength must 
 be provided, and we know also, approximately, the relative strength 
 or carrying capacity of the different teeth when used as abutments. 
 This is another forward step, and an important one. 
 
 There is still another point, recently impressively brought 
 to the fore, and a very important point it is. A very serious charge 
 has been brought against crown and bridge-work by our medical 
 brethren. They claim that as generally designed and constructed, 
 crown and bridge-work is often a serious menace to the patient's 
 health. That many serious ailments have been caused and main- 
 tained by septic conditions associated with crown and bridge-work 
 often worn by the patient with great comfort and satisfaction. The 
 proof presented is so strong and' convincing as to challenge inves- 
 tigation, and prompts the question, Why? 
 
 This brief resume of the progressive development of crown and 
 bridge-w^ork will no doubt have suggested to the thoughtful reader 
 the answer to this important question, and may, perhaps, have 
 suggested another. Why was not this discovered earlier, when the 
 art was crude, and the work in all its phases more imperfectlj'^ done? 
 
 IMedical science has made a marvelous advance during recent 
 
IXTliODLCTWX Nlil 
 
 years in tracing pathological lesions to their causes. Man>' dis- 
 orders that were formerly treated with indifferent success, by 
 methods suggested by the symptoms developed, are now recognized 
 as pathological conditions due to remote causes, causes at times 
 located far from the seat of trouble, and seemingly to the un- 
 scientific observer, having no connection whatever with it. The 
 cause recognized and removed, the disease is cured. 
 
 This has been the case in many instances to wearers of crown 
 and bridge-work. They have suffered, in some cases for years, with 
 but little relief until the medical attendant was led to suspect 
 that septic infection was the real cause. A careful, step-by-step 
 diagnosis by exclusion has located this in a highly priced piece of 
 bridge-work, a masterpiece of prosthetic dentistry. Its removal 
 has disclosed a horrible condition of affairs. A judicious use of 
 the forceps and oral prophylaxis, followed })y a rapid cure, proved 
 the diagnosis correct. 
 
 In order to purge crown and bridge-work of any possible stigma 
 now resting upon it, our profession must make practical use of the 
 knowledge gained by experience, and that furnished by the research 
 and observations of our medical brethren. Xo half-way measures 
 will suffice. It must be made aseptic from the foundations up. 
 All pathological conditions must be thoroughly and radically 
 treated, and the treatment continued until a cure is effected and 
 all sources of septic invasion remo\ed. 
 
 In comparing the general output of crown and bridge-work as 
 we see it today with tliat of the pa.st, there is not that marked 
 difference in its diaracter we have a right to expect, considering 
 the tremendous advances which have been made in our knowledge 
 of the physiology and pathology of the dental pulp, and the technic 
 of root and pulp-canal treatment. This is really where the trouble 
 is. This knowledge has not l)een utilized as it should have been 
 in making crown and bridge-work better and safer. 
 
 Modern methods of treating such i)athological conditions as 
 lia\e been resj)onsible for the undoing of crown and i)ridge-work 
 are radical, and radically different from those which liaxc prevailed 
 in the past. I'ul)) and pul|)-canal treatment as it should be done 
 when prei)aring lor cnnvn and bridge-work is tedi()us, it takes time, 
 it requires patience and exacting care to make sure that it is well 
 done. The mechanical i)reparatioti of roots and abutmeiit teeth, as 
 we now know the.\- must be prepared, is \-er\ different from the 
 slijjshod methods of the past. It is regrettable that these matters 
 
xiv INTRODUCTION 
 
 have not been generally realized. Had this specialty correspond- 
 ingly developed with the development of our knowledge of the 
 various technical procedures underlying the scientific construction 
 of bridge-work, we should have so improved the character and 
 efficiency of the average output of bridge-work, as to have made it 
 beyond all comparison better than the bridge-work of the past. 
 
 In order that these results may yet be accomplished by the means 
 already at our command, it is necessary that we give earnest atten- 
 tion to, not only the underlying principles upon which all good 
 bridge-work is founded, but also sympathetic and careful attention 
 to the infinite number of minor as well as major details, both 
 technical and artistic, which are collectively necessary to the 
 attainment of excellence in this and in all things which are worth 
 doing well. 
 
CROAVN AND BRIDGE-WORK. 
 
 CHAPTER 1. 
 ARTIFICIAL CROWNS. 
 
 When the natural crown of a tooth lias become broken down 
 or decayed to such an extent that it is impracticable to restore 
 it by means of fillings or inlays it becomes necessary to resort to 
 some other means of restoration to enable it to perform its normal 
 function. This is done by means of an artificial crown. 
 
 There are three types of crowns which are used for this purpose, 
 dift'ering from each other chiefly in the manner of their retention, 
 the first type being retained in position by means of a pin or post 
 inserted into the enlarged pulp canal. The second is hel I in place 
 by means of a collar or band which encircles the stump of the tooth. 
 The third is a combination of these two, having both a band and 
 post to give the necessary support. 
 
 The first of these is used almost exclusively in the teeth anterior 
 to the molars. The second is confined almost wholl>' to the molars 
 but at times is used as far forward as the bicuspids and under cer- 
 tain conditions for the anterior teeth. The third is used principally 
 in the anterior teeth, but is also at times indicated in the posterior 
 teeth. 
 
 Fiu. 1 
 
 There are two classes of this first type of crown; one being that 
 in which the post is an integral part of the crown itself, being baked 
 into the porcelain or soldered to it fl''ig. I j. In the first class we 
 2 
 
18 ARTIFICIAL CROWNS 
 
 have the Logan crowns and the pin and post crowns. The second 
 class is one in which the crown and post are separate, there being 
 an opening in the base of the crown or entirely through it in 
 which the post is cemented or otherwise fixed (Figs. 2 and 3). 
 
 Fig. 3 
 
 Examples of this class may be found in the Bonwill crowns, 
 Davis crowns, Justi crowns, and the English tube teeth. 
 
 There is little choice between the different crowns of these types. 
 That which best meets the requirements of a given case in mold, 
 shade and texture may be chosen. 
 
 There are also two classes of the second type of crown. The 
 first is used exclusively in the back of the mouth, being made 
 entirely of metal and is represented by the gold shell crown. The 
 second class is a combination of both metal and porcelain, having 
 a band for retention, but the exposed portions, the face or occlu- 
 sal surfaces being covered with veneers or porcelain. An example 
 of this class may be seen in the jacket crown. 
 
 In the third type we have the so-called Richmond crown, or a 
 crown with a Richmond base and an all porcelain crown attached 
 to it. 
 
 These different types of crowns are used as single crowns, or as 
 abutment crowns, or dummies in bridge-work. 
 
 ESSENTIALS TO SATISFACTORY BRIDGE-WORK. 
 
 General Considerations. — When consulted regarding the advisa- 
 bility of inserting a piece of bridge-work, there are three funda- 
 mental factors to be considered: the number, position, and con- 
 dition, of teeth or roots available as abutments. The whole story 
 of requirements for this work may be summed up in these three 
 words. If the available teeth or roots are lacking in number, or 
 are unsatisfactory as to position or condition, an essential to success 
 is wanting, and the work is contra-indicated. 
 
 There are certain mechanical and scientific principles governing 
 this work and these same principles are involved whether we are 
 placing a bridge in the mouth or across a river. There must be 
 
ESSENTIALS TO SATISFACTORY BRIDGE-WORK 19 
 
 sufficient number of abutments to carry the weight which will be 
 imposed upon it, and their position and condition must be such as 
 to give stability to the structure, and to withstand any strain to 
 which it may l)e subjected, otherwise it will collapse. 
 
 Partial Plates vs. Bridge-work. — In a very large percentage, 
 probably in the majority of mouths where partial plates are now 
 worn, bridge-work could be used to much better advantage, and 
 would be far more serviceable than are the plates. Partial plates 
 are always decidedly objectionable and are to be avoided if possible. 
 The plates, almost invariably injure the soft tissues and the ad- 
 joining teeth, the pressure gradually forcing the gum away from the 
 necks of the teeth, which are abraded by the constant movement 
 of the plate, and in many instances this results in their loss. This is 
 especially true where the plate is of small dimensions, carrying 
 but one or two teeth. 
 
 In every case, or at least all but the simplest, it is best to take 
 plaster impressions of the mouth and make accurately articulated 
 models, trimmed so that they may be examined from every point 
 of view, both from the inside as well as the outside. These models 
 shoulfl be studied carefully before deciding on any definite line of 
 operation. 
 
 The number, position, and general condition of the teeth being 
 satisfactory, the success of a crown, or of a bridge, depends en- 
 tirely upon the preparation of the teeth, or roots, which are to 
 serve as abutments. By this preparation is meant not simply the 
 mechanical trimming of the teeth or roots for the reception of the 
 bands or posts, but it begins at the beginning with the treatment 
 of any pathological conditions which may be present, the dexital- 
 izing and removal of the pulp, and the sterilizing and filling of 
 the canals. This will be considered in the succeeding chapter. 
 
 The accompanying illustrations (pages 20 and 21) are accurate 
 reproductions from Traite de la Partie Mecanique de Fart du 
 Chirurgien-Dcnfis-fc, par (\ F. I)elal)arre, i)ublished in 1S2(). They 
 give a ver\' good idea of the crown work which was done at that 
 time. 
 
 We are cnablcl to reproduce these figures through the kindness 
 of Dr. K. J. Uanhofer, of New York. 
 
20 
 
 ARTIFICIAL CROWNS 
 
ESSENTIALS TO SATISFACTORY BRIDGE-WORK 21 
 
 A 
 
 0/1 
 
CHAPTER II. 
 
 PATHOLOGICAL CONDITIONS IN THEIR RELATION 
 TO CROWN AND BRIDGE-WORK. 
 
 It is not the intention of the writer to consider the treatment of 
 pathological conditions except as they are directly related to 
 crown and bridge-work. Inasmuch, however, as a healthy condition 
 of the teeth and roots utilized as supports for crowns and bridges 
 is a fundamental to success, pathological conditions of the teeth 
 and their treatment, is of the utmost importance to crown and 
 bridge-workers. 
 
 Each factor making for success or failure must be carefully 
 considered, and nothing left to chance. Loose teeth need not 
 necessarily preclude the idea of inserting a bridge; they should be 
 carefully studied in order to determine the cause, and whether or not 
 they can, by thorough treatment, be brought to a normal, healthy 
 condition. If this is impossible, then, of course, unless other teeth 
 are available, a crown or bridge is not to be thought of. 
 
 Loose Teeth. — Looseness of teeth may be brought about by many 
 causes, such as pyorrhea alveolaris, dento-alveolar abscess, kidney 
 troubles, malocclusion or want of occlusion, etc. Some of these 
 causes may require the services of a physician, those due to faults 
 of occlusion, and many others, will usually yield to thorough dental 
 treatment. Nothing should be done, however, until the cure is 
 effected and the teeth have become firm. 
 
 Pyorrhea Alveolaris. — A case of pyorrhea, if it be serious, is gener- 
 ally better referred to a specialist, as one specializing in this par- 
 ticular branch, will probably get better results than another who 
 treats it only occasionally. 
 
 In its earlier stages a cure may be effected by thorough in- 
 strumentation, and cleansing the parts affected with antiseptic 
 solutions. The affected teeth, when the disease is well advanced, 
 are generally useless as supports for crowns or bridges. 
 
 Pyorrheal Conditions. — Conditions are frequently met with in the 
 oral cavity resembling pyorrhea which are not really this disease. 
 
PUTRESCENT PULP CANALS 23 
 
 They may l)e caused by some Icx-al irritation, such as Ugatures 
 forgotten, and left around a tooth, below the gum margin, causing 
 irritation resulting in infection, and a flow of pus. The same effect 
 may be brought about by a splinter, as from a tooth pick, or 
 some such like irritation. These cases may, at first sight, be 
 mistaken for pyorrhea. The removal of the cause usually effects 
 a cure. 
 
 Putrescent Pulp Canals. — In treating a putrescent pulp canal the 
 first stej) is to cleanse it mechanically, as thoroughly as possible. 
 The greatest care must be exercised in doing this so as not to force 
 any of the putrescent matter or gas through the apical foramen. 
 The instruments best suited for this purpose are the Donaldson 
 canal cleansers. These instruments are barbed in such a manner 
 that the barbs follow around the shaft in the same manner as 
 does the thread on a right-hand screw, so that by rotating the 
 instrument is drawn into the canal without the necessity of using 
 the slightest force. 
 
 The instrument is dipped in carbolic acid or other strong anti- 
 septic, the point placed in the canal and the instrument turned 
 slowly to the right. As it is carrierl into tlic canal it is frequently 
 withdrawn and cleansed of the matter adhering to it, until the 
 vicious matter is entirely removed. By working in this manner there 
 is no danger of carrying any of the putrescent mass through the 
 end of the root. It is of the greatest importance that not the 
 slightest force be used on the instrument. After the bulk of the 
 softened mass is removed, the sides of the canal are scraped with 
 the same instrument, until it is fairly well cleansed. 
 
 Sodium and potassium, or sodium dioxide, is then used, being 
 carried into the canal with a fine instrument, })urning out any of the 
 disintegrated pulp tissue which remains in the root. This should 
 be done thoroughly, and a little of the sodium and potassium 
 left in the canal until a subseciuent sitting. When the patient 
 returns, the treatment with the sodium and potassium is repeated, 
 after which the canal should be washed out with a solution of 
 bichloride of rnercnry and jxToxide of hydrogen, "^riie caiiid is then 
 thoroughly flrierl and filled. 
 
 In the absence of the sodium and potassium, or sodium dioxide, 
 formalin may be used, but this should not be sealed in the root, 
 unless the foramen is closed, or is very minute, as it is an active 
 irritant and may cause consideral)]e pain and trouble. 
 
24 PATHOLOGICAL CONDITIONS 
 
 Sterilizing a Pulp Canal with Formalin. — In sterilizing a pulp canal 
 with formalin, the following method will prove effective. After 
 the root has been as thoroughly cleansed mechanically as is possible 
 under the existing conditions, it is dried with alcohol and the canal 
 wiped out with a strong solution of formalin, running from 10 to 
 40 per cent, the full strength of the solution, using a wisp of cotton 
 twisted around a broach as a carrier. It is then dried with hot 
 air or a heated root-drier, thereby driving the formalin into the 
 tooth structure. This operation is repeated a number of times until 
 it is certain that the root has been thoroughly sterilized, after which 
 it may be filled. 
 
 Where there has been a slight irritation in the apical region, it is 
 a good plan to enlarge the foramen very slightly before treating, 
 and a dressing of tricresol and formalin may be sealed in the canal 
 and left for a day or two, to be repeated if necessary. 
 
 Where there has been an excessive and continued irritation, it is 
 best to treat the case in a thorough manner, opening through the 
 process to the apex, giving it the same treatment indeed, as in the 
 case of a dento-alveolar abscess, and then filling the root at once. 
 
 When on opening into a tooth, if the pulp is dried up and in a 
 mummified condition, the canal should be given the same treatment 
 and care as though the pulp was putrescent. 
 
 The same treatment should be employed in the case of cotton 
 filled roots, which are sometimes met with, without regard to the 
 condition they may seem to be in, foul or sweet. In a major- 
 ity of these cases the canals are in a putrid condition, and before 
 being utilized they should be treated as advised for the canals of 
 putrescent pulps. 
 
 PULP INFECTION AND TREATMENT OF RESULTANT 
 CONDITIONS. 
 
 There are many causes which may bring about the death of the 
 pulp and unless this condition is recognized very early and properly 
 treated, trouble of a more or less serious nature is liable to follow. 
 
 There are cases where the pulp has become devitalized and re- 
 mained quiescent for a number of years, the patient being unaware 
 that there is anything wTong with the tooth, but this is not of 
 frequent occurrence; more frequently the trouble becomes manifest 
 within a comparatively short time. 
 
 With the infection and decomposition of the pulp tissue, the 
 
PULP INFECTION AND TREATMENT 
 
 25 
 
 danger begins. A minute portion of this putrescent matter, or a 
 little of the gas generated by it, finding its way through the apical 
 foramen will set up an irritation and inflammation; infection follows, 
 resulting in the formation of a dento-alveolar abscess. This condition 
 is too often lightly considered, and an abscessed tooth looked upon 
 as of minor importance, when in reality it is a grave condition and 
 may cause serious pathological disturbances, and not infrequently 
 death has followed from septicemia caused by resorption of pus. 
 
 Dento-alveolar Abscess. — This is one of the troubles with which 
 the crown and bridge specialist is most frequently confronted. 
 As a general thing, it is also one of the easiest to cure. 
 
 In this as in every step in crown and bridge-work, thoroughness 
 is necessary to success, and unless one is willing to give the time 
 and attention necessary to effect 
 a cure, it is far better not to 
 attempt its treatment. 
 
 With the formation of pus 
 around the apex of the root, there 
 is a destruction of tissue extend- 
 ing in all directions, thus form- 
 ing an irregular cavity or sac 
 into which the apex of the root 
 extends (Fig. 4). 
 
 As the amount of pus increases, 
 it will gradually force its way 
 
 through the alveolar process and gum tissue, thus establishing a 
 fistula. 
 
 If there is a cavity in the tooth through which the pus, after 
 passing through the canal, may be discharged into the mouth, 
 there will be no external fistula; this is termed a blind abscess. 
 
 The treatment of an abscess which has no outlet for the pus 
 excepting that through the root of the tooth, should never be 
 undertaken. It is practically impossible to force the remedies 
 through the apical foramen into the pocket or sac of the abscess, 
 or to cleanse it thoroughly and remove the debris without having 
 an external fistula. Treatment through the root may relieve the 
 trouble temporarily, but it is liable to recur at any time. 
 
 In the case of an acute dento-alveolar abscess, where there is a 
 fistula established, a cure can generally be eU'ected c|uickly and 
 easily. It is not necessary to have the patient make daily visits, 
 as with proj)(T care it is xcry rarely that it is necessary to give it 
 
 Fig. 4 
 
26 PATHOLOGICAL CONDITIONS 
 
 more than one, or, at the most, two treatments, in order to effect 
 a permanent cure, but in doing this, every step of the operation 
 must be done thoroughly. 
 
 For many years the writer has had almost uninterrupted success 
 in the treatment of this trouble by using the following method : 
 
 The canal is first cleansed as thoroughly as possible mechanically, 
 using Donaldson's canal cleansers, or instruments of that type, 
 and scraping the sides of the canal thoroughly so as to remove every 
 particle of diseased tissue which can be reached. 
 
 Fig. 5. — Bulb syringe. 
 
 It should then be ascertained beyond doubt that there is an 
 open fistula, through which the remedies will readily flow, and this 
 can be done by using distilled water or a mild antiseptic solution, 
 after which the first agent used is hydrogen peroxide. 
 
 Objections have been strongly urged against the use of this agent, 
 the claim being much that it will cause necrosis and sloughing, but 
 during the experience of twenty-five years, the writer has not had a 
 single case where this has occurred. If the peroxide were forced into 
 a closed sac under pressure, then serious trouble might ensue, but 
 where there is a free vent there is, practically, no danger from its use. 
 
 Treatment of Acute Dento-alveolar Abscess. — In the treatment 
 of acute dento-alveolar abscess it is necessary that suitable in- 
 strument for injecting the remedies be used. A rubber bulb syringe, 
 with platinum point, known as an abscess syringe is most useful 
 for this purpose (Fig. 5). The capacity of the bulb of this syringe 
 is one-quarter of an ounce. 
 
 In order to insure the remedy being forced through 
 
 (^S^^^^ the canal and out through the fistula, it is necessary 
 
 to use a packing, preferably of rubber. This is very 
 
 easily made by forcing the needle through a piece 
 
 of heavy separating rubber, of sufficient size to entirely cover the 
 
 opening in the tooth or root, letting the end of the needle extend 
 
 a little beyond this rubber packing, as in Fig. 6. 
 
PULP INFECTION AND TREATMENT 27 
 
 The point is then introduced into the opening in the canal or 
 tooth and the rubber pressed tightly over the opening and around 
 the needle with a pair of cotton-pliers. This will efFectually prevent 
 the fluid from escaping at this point, and will insure its reaching 
 the place where it is needed. 
 
 The abscess is first washed out with sterile water so as to ascertain 
 that there is a free vent, then hydrogen peroxide is forced very 
 slowly through the root and out of the fistula, and this is continued 
 as long as there is any eftervescence. It is sometimes necessary 
 to use a large amount of the peroxide before the pocket is entirely 
 cleansed. At times one or two ounces or even more may be required, 
 but it should be continued until the solution comes through perfectly 
 clear. 
 
 The hydrogen peroxide is followed by the standard solution of 
 aromatic sulphuric acid. This solution is used in its full strength 
 as given in the United States Pharmacopeia and contains about 
 10 per cent, by bulk, or 20 per cent, by weight, of sulphuric 
 acid. 
 
 The amoiuit of the aromatic sulphuric acid used is from one- 
 quarter to one-half of a syringeful, or from one-sixteenth to one- 
 eighth of an ounce, or at times even more than this. 
 
 The point of the syringe is inserted into the canal and the rubber 
 packing pressed tightly against the tooth, as with the hydrogen 
 peroxide, and the acid forced through very slowly. This heljrs to 
 destroy any remaining diseased tissue and acts as a stimidant. 
 The acid should be met, as it comes through the fistula with a 
 syringe full of a saturated solution of bicarbonate of soda, so as 
 to counteract, or neutralize, the action of the acid before it comes 
 in contact with the teeth and the soft tissues of the mouth. The 
 bicarbonate of soda should be used freely, as much as three or 
 four syringe fulls during the injection of the acid, and afterward 
 the mouth should be rinsed freely with the same. 
 
 After the acid has been used, the root should be filled at once. 
 If it is left open for any length of time, infection may recur, and it 
 will be necessary to repeat the operation as there is a serious risk 
 of reinfection as long as the root remains open. 
 
 After treating an abscess in this manner and filling the root canal, 
 it will generally recpure from ten days to two or even three weeks 
 before the parts are finally healed. During this time there will be a 
 discharge of blood and serum through the fistula, presenting the 
 aj)pearance of pns, but this is a perfectly nalnral condition, as there 
 
28 
 
 PATHOLOGICAL CONDITIONS 
 
 is a normal sloughing of the disintegrated tissues which must be 
 expelled as the parts are healing. 
 
 At times, when the edges of the wound are fresh, the fistula 
 may close up at once, or within two or three days, but it will break 
 out again, and this may be repeated several times; it will not heal 
 finally until all of the sloughed tissue has entirely disappeared and 
 healthy granulations have replaced it. 
 
 It is very rarely, in the case of an acute abscess, that it is necessary 
 to repeat this treatment, but it should be remembered that the 
 cure depends entirely upon the thoroughness with which the 
 operation has been performed. 
 
 Establishing a Fistula.- — If there is no external opening, and the 
 abscess has been draining through the pulp canal of the tooth, it is 
 necessary to establish a fistula. Occasionally, by sealing the 
 opening through the tooth for a time, nature will establish one with 
 comparatively little discomfort to the patient, but if this cannot 
 be done, it becomes necessary to make an 
 opening through the gum and process. 
 
 A spear-pointed drill is best suited for this 
 purpose; it should be of a large size, sharp, 
 and perfectly sterilized. 
 
 Locating the Apex of the Root.: — It is neces- 
 sary to first locate the apex so as to know 
 exactly where to drill. The foramen is slightly 
 enlarged in order to ascertain the exact length 
 of the tooth or root. This can be done with 
 a small hooked broach, passing it through the 
 canal and catching the hook over the end of the 
 root. A small piece of rubber dam is pressed 
 down over the broach to the incisal edge of the 
 tooth or against the end of the root (Fig. 7). 
 The broach is then removed. The position of 
 the rubber indicates the exact distance from the 
 end of the root or the incisal edge of the tooth to 
 the apex. A perfectly straight broach is then in- 
 serted, being of a larger size than the one used 
 in measuring the length of the root, one that 
 will wedge in the canal with the end passing 
 through the foramen into the pocket, the handle extending beyond 
 the incisal edge of the tooth, as in Fig. 8, a. By following the line 
 of this broach the exact direction of the canal is indicated. 
 
 Fig. 7 
 
PULP INFECTION AND TREATMENT 
 
 29 
 
 By placing the hooked broach over the gum and bringing the 
 piece of rubber dam even with the incisal edge of the tooth, or with 
 the end of the root, it will show exactly how far from the incisal 
 edge to drill in order to strike the pocket 
 or the end of the root (Fig. 8, b). 
 
 Using these two as a guide, and follow- 
 ing the direction of the broach which is 
 wedged into the root, the drill can be 
 directed so as to reach with certainty the 
 apex. This operation can be quickly and 
 easily performed by using a general anes- 
 thetic, but it is very rarely that a general 
 anesthetic is indicated, as the time re- 
 quired is so short that a local anesthetic, 
 used hypodermically, will give satisfac- 
 tory results. 
 
 Painless Insertion of the Hypodermic 
 Needle. — With patients who are of a 
 highly nervous temperament, or where 
 the tissues are extremely sensitive, the 
 l)ain caused by the insertion of the hypo- 
 dermic needle is at times almost as great 
 as would be the pain of the operation if 
 it were performed without an anesthetic. 
 The pain caused by the forcing of a 
 hypodermic needle into the soft tissue 
 
 may be greatly lessened if, when the syringe is filled, the flat- 
 tened side of the point of the needle is pressed tightly against 
 the gum and the end of the finger pressed ov(t the point, at the 
 same time pressing on the plunger. It is held thus for a moment 
 and gradually the needle is forced into the tissue, the pressure on 
 plunger being kept up all the time. In this way the tissues are 
 anesthetized in advance of the needle, and the operation rendered 
 almost painless. The gum should be first cleansed and dried with 
 alcohol and it is well to touch it with iodine before attempting 
 to insert the needle. 
 
 The opening through the gum to tlie process can be made with a 
 lance, a trephine, or by using a sharp spoon-shaped excavator; with 
 the lMtt<T, by dipping it in carbolic acid and scraping the gum a 
 little bit, then di])ping in the aci<l again and repeating this operation 
 until the process has been reached. It is possible thus to go through 
 
 Fig. 8 
 
30 PATHOLOGICAL CONDITIONS 
 
 the tissue to the process without drawing blood, and causing very 
 little or no pain to the patient. 
 
 It is possible to take a drill, with the edges of the blade very sharp, 
 and drill directly through the gum, but unless the edges of the drill 
 are very sharp, there is danger that the gum tissue may be caught, 
 and twisted around the drill, and badly torn. The use of the lance 
 is the quickest and easiest method, making a straight incision 
 on a line with the long axis and over the apex of the tooth, or, if it 
 is desired, a crucial incision may be made. 
 
 The point of the drill is placed over the apex of the root as indi- 
 cated by the broaches which are serving as guides. 
 
 The engine should be run very rapidly and the aim be to strike 
 the end of the broach which is wedged in the root canal, at about 
 the point where it emerges through the foramen. 
 
 Some operators, especially among the younger practitioners, are 
 timid and dread performing an operation of this kind, but it is 
 .very simple and is quickly done, not requiring more than a few 
 seconds at the most. 
 
 As soon as the pocket is entered, a fistula is established through 
 which the remedies can be forced freely. 
 
 Chronic Dento-alveolar Abscess. — When an abscess has become 
 chronic, extending over a period of several years, a necrotic condition 
 in the apical region is established, and a portion of the root will 
 also be necrosed. This necrosed area must be entirely cut away 
 and the diseased portion of the root removed in order to effect a 
 cure. 
 
 Treatment. — The apex is located in the manner already described. 
 The incision in the gum should be larger than where simply estab- 
 lishing a fistula. It should be at least one-half inch in length. A 
 large spear-pointed drill is first used and is followed by a large 
 Coarse rose or pear-shaped bur to enlarge the opening through 
 the process and bur away the necrosed bone. The necrosed bone 
 must be entirely removed, and during the operation, frequent 
 examinations should be made with an explorer or excavator, and the 
 burring continued as long as there is the slightest trace of necrosed 
 tissue. This can readily be determined by the sense of touch. 
 The necrosed bone has a coarse or honey-combed texture, readily 
 recognized by the instrument, while the healthy bone is smooth 
 in comparison. 
 
 After the diseased tissue is entirely removed, the wound is washed 
 out with sterile water, and is then given the same treatment as 
 
PULP INFECTION AND TREATMENT 31 
 
 already described in the case of an acute abscess using hydrogen 
 peroxide and aromatic sulphuric acid, after which the root is filled 
 at once. 
 
 Amputation of the Root End for the Relief of Dento-alveolar Abscess. 
 — In amputating the apex of a tooth root, some operators advise 
 the use of a fissure bur, cutting straight across the root, thus re- 
 moving the end in one piece. 
 
 In the writer's opinion, this is an error, as the piece is left in the 
 pocket and at times the part cut awaA' is so large that it can only be 
 removed by greatly enlarging the opening through the process. If 
 it is not removed it will act as an irritant and there will be a recur- 
 rence of the trouble. 
 
 A large rose bur or pear-shaped bur is indicated for this work, 
 starting from the apex and burring away the root gradually as 
 far as is necessary, the root is thus reduced to fine particles which 
 are easily washed out from the pocket. The after-treatment is the 
 same as that for an acute abscess. 
 
 ]\Iany operators prefer filling the root before amputating. When 
 this is done, the filling is burred away with the root. With this 
 method, there is always a possibility of loosening the root filling, 
 and thus leaving a chance for future trouble. 
 
 The writer believes that in an operation of this kind, the most 
 satisfactory and certain method is to fill the root after amputating. 
 The length of the root is taken with a hooked broach, and a canal 
 plugger is selected which will reach only to within about one-eighth 
 of an inch of the end, the same as in the filling of a root with an 
 enlarged foramen. 
 
 The j>ocket is first treated the same as for an acaite abscess, 
 being washed out with hydrogen peroxide, followed with aromatic 
 sulijhuric acid. 
 
 An instrument having a broad fiat end is j)assed through the 
 opening in the process and pressed tightly- over the end of the root, 
 being held firmly in that position with the left hand. The canal 
 is then thoi^oughly dried. 
 
 A gutta percha point, which has previously been selected and 
 which is slightly larger than the plugger which is to be used, the 
 length being about that of the canal between the end of the plugger 
 and the end of the root, is fastened to the i)lugger point by heating. 
 This is dipped in eucalyptus oil and packed tightly against the 
 instrument which covers the end of the root. H\ filling the root 
 in this way, we may be (piite sure that the filling is firm, and there 
 will ])(' no liability of leakage. 
 
32 PATHOLOGICAL CONDITIONS 
 
 If the crown of the tooth is good, and the canal is not to be used 
 for the reception of a post, the entire canal may be filled with the 
 gutta-percha, packing it tightly against the instrument covering 
 the end of the root. 
 
 If the wound is large, it is better that it be packed lightly with 
 antiseptic gauze, which will act as a seton and keep the part drained. 
 This dressing should be changed every two or three days and the 
 wound washed out with an antiseptic solution. Healthy granulation 
 will quickly begin and the depth of the wound will diminish as it is 
 filled in with healthy tissue. The treatment should be kept up 
 until the wound has become filled with healthy tissue to within about 
 one-quarter of an inch of the opening. The dressing and washing 
 may then be discontinued. Healing will be complete within a very 
 short time, if all of the necrosed tissue has been removed. If 
 this does not take place, it is evidence that there is still remaining 
 some diseased tissue, and further treatment, looking to its removal, 
 is needed. 
 
CHAPTER III. 
 
 CROWN AND BRIDGE-WORK IN RELATION TO THE 
 
 VITALITY OF THE PULPS IN SUPPORTING 
 
 TEETH. 
 
 For many years it was a question as to whether it were l)est to 
 devitalize a tooth preparatory to crowning, or to preserve the pulp 
 alive. There was rarely held a dental meeting of any importance 
 where this subject was not discussed. ]\Iuch was said both for and 
 against devitalizing, some claiming that the pulp should always be 
 retained wherever it was possible, devitalizing used only as a last 
 resort, while others held an opposite opinion. 
 
 The ^^Titer himself, at the beginning of his work, considered it 
 almost a capital offence to destroy a pulp if there was any possible 
 way of retaining it and still utilizing a tooth as an abutment. 
 
 After a time, however, it was found that the teeth from which 
 the pulps had been removed were doing as good work, or even giving 
 better results than those, in which the pulps had been preserved. 
 
 The excessive irritation caused by removing the enamel (which 
 was necessary in order to have a closely fitting band) and also the 
 irritation caused by cementing the piece in place seemed to excite 
 an overstimulation of the pulp, resulting in the deposition of 
 secondary dentin, the formation of pulp-stones, and kindred 
 troubles. 
 
 It is generally recognized at the present da\-, that the pulp is 
 purely a f(jrmative organ, and after it has performed its function 
 it is no longer necessary to the life and health of the tooth, and a 
 tooth from which the i)uli) has been removed and the canal has 
 been properly filled will do the work as a support for a bridge as 
 well or even better than one in which it has been retained. 
 
 Exceptions. — There are a few exceptions to this rule. In the 
 case of a patient of advanced years, where the tooth has been broken 
 or worn down by attrition, so that it can be trimmed or shaped witli 
 little or no pain, or where the pulps of the teeth may have receded 
 to such an extent that the canals have become nearly obliterated, 
 it is permissible, and many times advisable, to crown such teeth 
 without undertaking to devitalize. 
 
34 CROWN AND BRIDGE-WORK 
 
 In the case of very young subjects the teeth should never be 
 devitahzed for the purpose of placing a shell crown or a bridge, as 
 the teeth are not then fully developed, and the pulps should be 
 retained until the patient has matured and the roots are perfectly 
 formed. It is rarely that pulps should be devitalized until the 
 patient is at least seventeen or eighteen years of age. 
 
 In the case of a very young subject, where teeth have been lost 
 and the patient, perhaps, has been under orthodontic treatment, 
 and it is necessary to bridge the space in order to retain the teeth in 
 proper occlusion, a temporary bridge may be made, mutilating the 
 teeth as little as possible, simply making space enough between 
 those which are to serve as abutments and adjoining teeth to allow 
 for the thickness of a metal band, but not cutting through the enamel. 
 After the work has been placed in the mouth, it should be frequently 
 examined and a careful watch kept over the patient until such time 
 as it may be advisable to insert a permanent fixture. 
 
 THE CAUSE OF SOUND TEETH DISCOLORING AFTER 
 DEVITALIZATION. 
 
 There are times when a patient may object to having one of the 
 anterior teeth devitalized for fear that it may become discolored. 
 If the operation of devitalizing, and the after-care of the tooth has 
 been properly done, there will be no discoloration. The discolora- 
 tion of a tooth from which the pulp has been removed is d;ie not 
 to the fact that the tooth has been devitalized, but to its improper 
 treatment after devitalizing. 
 
 Quoting from his own experience, the writer does not recall a 
 single case in which a tooth has become discolored after removing 
 the pulp, but he has seen and treated many such cases, and has 
 invariably found unmistakable evidence of the manner in which 
 this condition was brought about. 
 
 The tooth is opened from the lingual or palatal side, or through 
 a cavity, perhaps, on the mesial or distal side, drilling in the direc- 
 tion of the apex. The pulp is removed through this opening and 
 the canal cleansed and filled. Usually it will be found that this part 
 of the work has been well done, but the operator has not gone far 
 enough in his work to prevent the trouble. As will be seen in the 
 illustration (Fig. 9), the horn of the pulp extends far up into the 
 crown of the tooth, while the opening has been made far below it. 
 The result is that this extension of the pulp remains in the tooth 
 
DEVITALIZATION OF THE PULP 35 
 
 after the canal and cavity has been filled, as in Fig. 9, where it 
 decomposes, and in time the tooth structure becomes infiltrated 
 with this putrescent matter causing the discoloration. 
 
 The writer does not remember, and has no record of ever ha^•ing 
 opened up a discolored tooth where he has not found the conditions 
 as described above. 
 
 After the canal has been opened, the pujp chamber should be 
 enlarged sufficiently near to the incisal edge of the 
 tooth to permit of the removal of every particle 
 of pulp tissue. This can be done with a rose 
 bur in the right angle hand-piece, working from 
 the lingual side, and opening it up enough so that 
 the extreme apex of the pulp chamber can be 
 reached, Fig. 10. After the pulp has been entirely 
 removed, the cavit^' is thoroughlv sterilized and ^^ „ t- ,« 
 
 . , " , Fig. 9 | Fig. 10 
 
 filled with cement of any suitable color. 
 
 Although, if the work of devitalizing and filling a tooth be properly 
 done, there will be no discoloration of the crown, there will always 
 be a slight difference in the opacity, owing to the removal of dentin 
 and the placing of the cement lining which may render it slightly 
 noticeable in certain lights, or when viewed from certain angles. 
 This will be especially true if the tooth so treated is standing next 
 to its mate, as would be the case if one of the centrals was devi- 
 talized. With the cuspid, there are so many teeth between it and 
 the corresponding tooth on the opposite side of the mouth, that 
 even a marked difference in color would not be in the least conspic- 
 uous. The following may be set down as a rule which should 
 invariably l)e observed. 
 
 Where there is a choice of teeth, one of which is to be devitalized 
 to serve as an abutment for a bridge, always devitalize the tooth 
 which danda farthest away from its vuite. 
 
 In the case of a lost lateral, the cuspid and central being in equally 
 good condition, the cuspid should be used as the abutment, but 
 if the central incisor is badly decayed or broken, then of course 
 it will be policy to utilize it. 
 
 DEVITALIZATION OF THE PULP. 
 
 When it is found necessary to deviudize the pulp of a tooth |)rior 
 to its preparation for an artificial crown, there are several (juestions 
 to be considered. The first of these is: In which of the methods 
 
36 CROWN AND BRIDGE-WORK 
 
 that may be employed is there the least danger of irritation or 
 injury to the tooth or its adjacent parts? (2) In what way may the 
 operation be performed with the least pain to the patient? (3) 
 How can it be most quickly and easily accomplished'' 
 
 Arsenic. — There are several methods and agents employed for 
 the devitalization of the pulp, any of which may be indicated under 
 certain conditions. Among the agents that are generally used for 
 this purpose, arsenious acid has been longest in use and more 
 generally employed. It is the one, however, which requires the 
 greatest care in its use; is dangerous in unskilled hands, and is not 
 always certain in its action. 
 
 Dr. Herman Prinz's Method. — Innumerable formulas for compounds 
 of arsenic with other drugs are suggested for dental purposes. The 
 principal object has always been to combine the arsenic with an anes- 
 thetic. If the pulp is in a normal condition, very little or no pain 
 is manifested by the arsenical application; if the nerve cells are 
 inflamed or are undergoing necrobiotic changes, the increased irri- 
 tation brought about by the powerful oxidation and reduction as a 
 result of the pharmacologic action of arsenic increases the already 
 existing neuritis and more or less severe pain results. Arsenic 
 is very diffusible; it quickly destroys the nerve endings, and con- 
 sequently there is little chance for the anesthetic which may be 
 added to it to exercise its specific function. For this very reason it 
 is questionable if the addition of a local anesthetic is of any benefit. 
 
 A more rational procedure consists in applying to an aching pulp 
 a concentrated solution of a local anesthetic-cocaine, novocain, 
 etc., prior to the introduction of the arsenical paste. Tanning 
 agents are frequently added to the paste for the purpose of changing 
 the pulp tissue to a leathery, material, so as to facilitate its ready 
 removal. 
 
 Tannic acid or the various forms of formaldehyde are useful 
 for this purpose. It is better practice to apply such agents after 
 the arsenic dressing has been removed; the less we interfere with 
 the absorption of the arsenic, the better and quicker will be the 
 results. 
 
 As a vehicle for the paste, only such media as are more or less 
 solvents of arsenic, and which allow ready absorption by the pulp, 
 are justified. Glycerin is preferable to any other medium. Lanolin, 
 a natural wool fat, has been recommended; it, however, prevents 
 the ready absorption of the paste. Phenol, creosote, or the essen- 
 tial oils, and similar liquids, have been used for many years as 
 
DEVITALIZATION OF THE PULP 37' 
 
 vehicles for the paste; their influence on the action of arsenic is 
 apparently of very little consequence; they certainly do not exercise 
 their typical pharmacologic action in this connection. Strong 
 coagulants should not be used, as they hinder the ready absorption 
 of the poison by forming a scab. 
 
 To give a distinct color to the paste, very small quantities of 
 carmine or lampblack may be added. Some practitioners prefer 
 to apply arsenic in the form of a paste mixed with cotton fibers, 
 or in the form of paper disks saturated with a soft paste. Arsenical 
 fiber is prepared by mixing cross-cut cotton with the paste, and the 
 disks are made by saturating very small squares of hard white 
 blotting paper with the thin paste, which are then dried and 
 preserved. 
 
 Prior to the application of arsenic, the cavity should be excavated, 
 and if possible the pulp should be thoroughly depleted, either by 
 puncturing the organ or by producmg artificial anemia. Szabo 
 recommends lavage for this purpose — washing the pulp with hike 
 warm water, changed slowly to cold water. Quicker results are, 
 however, obtained by applying adrenalin chloride solution under 
 pressure. 
 
 The cavity must be free from blood, to prevent the formation of 
 inactive arsenic hemoglobin. If the pulp is inflamed and painful, 
 it is absolutely necessary to apply suitable remedies to relieve the 
 conditions before the paste is applied; an inflamed j)ulp materially 
 hinders the ready absorption of arsenic, and continuous servere 
 pain is certain to follow. A mixture of tannic acid, cocain hydro- 
 chlorid, and liquid phenol is serviceable for this purpose. These 
 remedies, if sealed into the cavity, usually alleviate the condition 
 in from twenty-four to forty-eight hours. 
 
 If pus is present, it must be drained oft', and washed away with 
 a mild, warm antiseptic solution. Pulp nodules occasionally obstruct 
 the ready diftusibility of the chemical. Removal of these calcareous 
 deposits by means of sulphuric acid or by a drill, after cocain 
 pressure anesthesia has been applied, is indicated. Cocain should 
 never be applied cataphorically under these conditions, as the electric 
 current will drive the previously applied arsenic through the a])ical 
 fijramen into the soft tissues. Occasionally one meets a ])atient 
 who presents an unexplained idiosyncrasy to the action of this 
 chemical. 
 
 TIk; cavity lor tiie recejAion of the arsenical aj)i)lication should 
 l)e of ready access, and so jjrepared as to easily retain the temporary 
 
38 CROWN AND BRIDGE-WORK 
 
 filling. The arsenical compound is preferably placed in direct 
 contact with the freely exposed pulp by means of a blunt instrument, 
 or on a depressed metallic disk or a piece of cardboard, or on cotton 
 or spunk. Close contact insures quick action. Arsenic will act 
 by osmosis, although slower, through any thickness of dentin. 
 This very fact is the reason its use as a remedy for hypersensitive 
 dentin has been abandoned; death of the pulp was invariably the 
 sequence of such a procedure. Some operators prefer to cover the 
 arsenical dressing with an intermediate film of plain or oiled paper, 
 or pledget of cotton. The final sealing of the cavity consists of a 
 temporary filling of cement or of a gutta-percha preparation. 
 
 Extreme care should be exercised in this simple, yet most 
 important operation. Cotton fibers mixed with sandarac or mastic 
 varnish, to be used as a retaining medium should be avoided ; they 
 readily become foul in the fluids of the mouth, or they may leak, and, 
 besides, they swell, causing pain from pressure on the pulp. Kirk 
 has advocated the use of surgeon's rubber plaster where but a 
 portion of the tooth is left, carrying it around the tooth; it will 
 adhere satisfactorily for several days, or long enough to accomplish 
 the object. The gutta-percha preparations are the best media for 
 a temporary dressing seal; most experienced operators agree that 
 a cavity correctly sealed with this material ofters less possibilities 
 for the seeping through than the various cements or other materials. 
 In Europe Fletcher's artificial dentin is used universally for such 
 work. In applying the temporary stopping, it is very essential 
 to avoid pressure on the dressing. In approximal cavities, where 
 overhanging tooth substance prevents ready access, and therefore 
 presents danger of misplacing the arsenical dressing, gutta-percha 
 packed between the two teeth, and thus acting as a splint, is of 
 service." (Prinz.) 
 
 The writer believes that it is best to avoid the use of arsenic if 
 this can be done, as there is always a possibility of disturbances 
 following its use, such as arsenical pericementitis or even necrosis. 
 The former of these may not manifest itself immediately, but 
 sooner or later it may appear either in a mild or an aggravated form. 
 
 If the arsenic is not sealed in perfectly, especially if the cavity 
 extends below the gingival margin, necrosis is sure to ensue, which 
 in some cases might have far-reaching effects. Some patients 
 are peculiarly susceptible to this poison; and in the mouths of such, 
 arsenic applied for a few hours only would be sufficient to devitalize 
 the pulp completely, while in others it might remain for days with 
 
DEVITALIZATION OF THE PULP 39 
 
 seemingly little effect. In the former case, if it were left in the tooth 
 for an\- great length of time, it is almost certain that its action wonld 
 not be limited to the pulp itself, but would extend through the 
 foramen and beyond the apex and involve the surrounding tissue. 
 Especially would this be true if the foramen were somewhat enlarged. 
 The danger would be greater when usmg it on a young patient 
 than on an elderly patient, as in the former the root may not be 
 fully developed, and the foramen be widely patulous, in which cases, 
 carbolic acid, creosote or some such agent is indicated. 
 
 Cases also occur in which there is an imperfection in the walls 
 of the root-canals. A condition of this kind is fortunately very 
 rare and it is one which it is impossible to foresee and guard against. 
 If arsenic is used, disturbances which may result in serious injury 
 to the patient are unavoidable. Very rarely it may hap])en that 
 the pulp will resist the arsenic and repeated applications will have 
 no effect, in which event, some other method of devitalization 
 must be employed, although it will generally be fonnd that where 
 the pulp resists the action of the arsenic it is also likely to resist 
 the action of any other drugs which may be used. 
 
 By far the safest and most rapid method is immediate devitaliza- 
 tion. There are several different ways of accomplishing this by 
 surgical means, either by the use of a general or a local anesthetic 
 and extirpating the pulp at once with broaches or by using what 
 was termed the heroic method. This latter consists of driving the 
 pulp out with a pointed orange-wood stick without anesthetizing. 
 Since the aflvent of pressure anesthesia, this method has become 
 nearly obsolete, but there are still occasions where it can be used 
 to advantage and a few words descriptive of the technique will 
 not be out of i)lace. 
 
 The Heroic Method. — This method was successfully emplo.N'ed, 
 wherever jjossible, for many years by numbers of dentists who 
 feared the use of arsenic. It was characterized, by some as being 
 barbarons, and in fact, to one not familiar with the operation it 
 might seem to be so, but there are times where it is indicated and 
 if the operation is skilfully performed, it is instantaneous in accom- 
 plishing the result and comes as near being painless as any method 
 that can be employed. 
 
 It is especially indicated in the anterior part of the mouth and 
 for single-rooted teeth wlicre there is a full exposure of the pulp, 
 as in the case of a Utoth bnjken off from a blow, leaving the jnilp 
 protruding. 
 
40 
 
 CROWN AND BRIDGE-WORK 
 
 In employing this method of pulp extirpation, the pulp must be 
 well exposed and the operator should have a clear idea as to the 
 general shape and size of the pulp canal of the tooth to be operate 
 upon. The end of an orange-wood stick is whittled to correspond 
 in size to the canal, and is placed within convenient reach together 
 
 with a heavy, loaded mallet 
 (Figs. 11 and 12). 
 
 If the crown of the tooth 
 is to be removed, it may be 
 cut as nearly through as 
 possible by making a groove 
 labially and lingually with 
 a thin carborundum disk 
 and then it is nipped off 
 with excising forceps (Fig. 
 13). 
 
 The rubber dam should 
 be applied wherever it is 
 possible to do so. This hav- 
 ing been done, the point 
 of the orange-wood stick is 
 dipped in carbolic acid and 
 placed at the entrance of 
 the canal and a quick, sharp 
 
 Fig. 11 
 
 Fig. 12 
 
 Fig. 13 
 
 blow given it with the mallet. If the orange-wood has been 
 properly shaped, the pulp will be forced out between the canal 
 wall and the stick, or will be found clinging to the latter when it 
 is withdrawn. If this does not occur and any of the pulp remains 
 in the canal, it is carefully removed with barbed broaches. The 
 canal is then thoroughly cleansed, sterilized and filled. 
 
 This method is especially applicable to the single-rooted teeth, 
 but it has been successfully employed in the upper first bicuspids 
 
TREATMENT OF INFLAMED AND ACHING PULPS 41 
 
 and under favorable conditions, even to the larger canals in molars 
 where the crowns have been so badly broken down as to render the 
 canals easily accessible. In the upper molars, if the body of the 
 pulp has been removed, that portion in the palatal canal may almost 
 always be removed in this way, but the buccal canals are generally 
 too small and difficult of access. In the lower molars the pulp in 
 the canal of the distal root can be extracted, but in the mesial 
 canals there would be the same trouble as in the buccal canals 
 of the upper molars. 
 
 The operation is performed so quickly that the pulp is paralyzed 
 by the shock, and the pain should be no greater than that felt from 
 the slight prick of a pin. This happy result depends entirely upon 
 the careful following out of the technique, for at the hands of an 
 awkward manipulator it might cause the patient a great deal of 
 pain 
 
 TREATMENT OF INFLAMED AND ACHING PULPS PREPARA- 
 TORY TO DEVITALIZING. 
 
 It should always be borne in mind that neither arsenic nor an 
 anesthetic will act upon an inflamed or congested pulp. If the pulp 
 is in this condition, it has been the experience of the writer that a 
 dressing of oil of cloves or eugenol and sulphate of morphia is one 
 f)f the best applications for relieving the pain and reducing the 
 inflammation. A pellet of cotton is saturated with the oil of cloves 
 or eugenol and from one fortieth to one thirtieth of a grain of the 
 morjjhia is added to it. This is ])la('ed in the cavity and allowed 
 to remain until the pulp is quiescent, which will usually be in from 
 twenty-four to forty-eight hours, after which the arsenic or the 
 anesthetic may be ai)pli('d. 
 
 Pressure Anesthesia as Used in the Removal of the Pulp. — 
 With the introduction of pressure anesthesia the work of devitalizing 
 and removing pulps has been very much simplified. 
 
 A number of instruments have been d('\ iscd for anesthetizing 
 the pulp through the crown of the tooth. These are in the form of 
 a fjowerful syringe, by means of wliicli great |)r('ssnre can be 
 obtained. 
 
 An o|)cning is made tlirongli the enainci to tlic dentin with a 
 small bur, corresj)onding in size to the point of tlie syringe, which 
 is tli<'n i)lafed in this opening, and pressure applied to force the 
 anesthetic into the tooth structure. if the point (its (he hole 
 
42 CROWN AND BRIDGE-WORK . 
 
 accurately, in a majority of cases a satisfactory anesthesia will 
 be obtained. Many times, however, the syringe point does not 
 accurately fit the hole through the enamel, the anesthetic escapes 
 around it instead of being forced into the dentin, and in conse- 
 quence the application is ineffective. 
 
 Another, and in fact the original method, is to place the anes- 
 thetizing solution into a carious cavity, or an opening made for 
 the purpose, and over this a piece of un vulcanized rubber is placed. 
 This is pressed into the cavity with a strong instrument, forcing 
 a sufficient quantity of the solution into the tooth structure to 
 produce a satisfactory anesthesia. This latter method is the one 
 preferred by the writer. It the proper technic is carefully followed 
 positive and satisfactory results may be confidently expected. 
 
 One, and perhaps the principle cause of failure in applying the 
 pressure in this manner, is that the operator uses for carrying the 
 solution a piece of cotton entirely too large for the purpose. The 
 cotton is dipped into the anesthetic solution, placed in the cavity 
 and the pressure applied. If the mass of cotton is too large to be 
 covered by the rubber, some fibers are left projecting from the sides 
 of the cavity; when the pressure is applied, these give vent to the 
 solution, so that instead of its being forced into the tooth structure, 
 it escapes by following the cotton fibers extending over the edge 
 of the cavity. 
 
 It must be remembered that in applying pressure anesthesia in 
 any manner whatsoever, that the pressure must be direct and 
 positive, without any leakage, in order to force the solution into 
 the dentin or into the pulp. 
 
 Sterile Field for Operation. — Before applying pressure anesthesia 
 the greatest care must be used to insure a sterile field for the opera- 
 tion. If there is a gangrenous or septic condition of the body or 
 any part of the pulp, this must first be corrected and the parts made 
 as thoroughly aseptic as possible. If this is not done, septic gases 
 or matter may be forced through the apical foramen and cause 
 serious trouble. 
 
 In order to devitalize a perfectly sound tooth, an opening should 
 be made directly on line with the axis of the tooth so as to gain 
 direct and free access to the pulp. The first step is to grind through 
 the enamel. This is best done with a small stump carborundum 
 point, or a diamond disk or drill. The engine should be run rapidly 
 and the tooth kept flooded with iced water, which prevents heat- 
 ing, and also acts as a slight obtundent. By using ice-water freely. 
 
TREATMENT OF INFLAMED AND ACHING PULPS 43 
 
 the enamel can be quickly pierced, sometimes, even continued until 
 the pulp is exposed, with but little or no pain at all to the patient. 
 In the anterior teeth this opening is made on the palatal or lingual 
 side, while in the bicuspids and molars it is made directly through 
 the center of the tooth. Fig. 14. 
 
 The rubber dam is applied as soon as the enamel has been pene- 
 trated. If from any cause this cannot be done, napkins may be 
 substituted to keep the secretions of the mouth from encroaching 
 upon the field of operation. 
 
 The instruments needed should be ready at hand, convenient 
 for instant use. These shoukl include broaches for removing the 
 
 9 e 
 
 Fig. 14 
 
 Fig. 15 
 
 Fig. 16 
 
 Fig. 17 
 
 pulp from the canals, a large spear-pointed drill, large coarse rose 
 burs, a large cross-cut fissure bur, and one or two sharp spoon 
 excavators which may be used to remove the body of the pulp. 
 
 A large spear-pointed drill is the best instrument for drilling 
 through the dentin (Fig. 15). It should not be used for drilling 
 through the enamel, as the latter is so hard that it c^uickly dulls the 
 point, with the result that it not only takes more time, but the 
 increased pressure necessary to make it cut, heats the tooth, and 
 renders the ojjeration much more painful than it would be otherwise. 
 
 It is very rarely these instruments are well made as they come 
 from the dental depots. They are generally too thick and at the 
 cutting edges are not backed off sufficiently to cut well. They can 
 be greatly improved by first grinding them very thin and then 
 backing them off so as to leave a good sharp-cutting edge which 
 will cut deeply and cleanly into the denti?ie and clear itself readily. 
 (Fig. 10). If the edges are thick and straight across and have not 
 this clearance (Fig. 17), the drill will drag and heat, causing i)ain and 
 rendering the f)peration more lengthy and diflienlt. 
 
 The enamel having been picTced, the rubber dam is applied, the 
 tooth thoroughly dried, and the point of the drill placed on the 
 
44 CROWN AND BRIDGE-WORK 
 
 dentin pointing in direct line with the axis of the tooth's root, 
 with the engine running at high speed. As soon as the patient 
 experiences pain, it is time to begin the use of pressure anesthesia. 
 
 Ethyl chloride may also be used in making the exposure. In 
 drilling the opening, when the tooth begins to be sensitive, the 
 spray should be applied, intermittently at first, touching the tooth 
 only for an instant, repeating at short intervals, each time keeping 
 it on for a little longer period, until the tooth becomes insensible. 
 In this way the tooth is cooled gradually and the pain or shock 
 which occurs when the spray is applied directly and continuously 
 is avoided. The spear-pointed drill is now used, and if the tooth 
 again becomes sensitive before the pulp is reached, the spraying is 
 repeated. 
 
 There are a number of different preparations used in the devi- 
 talization or the anesthetizing of the pulp. Novocain seems to 
 be a favorite agent with many dentists. The writer, however, has 
 had excellent results from using the pure crystals of cocain in con- 
 junction with some fluid as a vehicle, usually favoring a local 
 anesthetic solution. 
 
 The local anesthetic, which seems to work best, and in fact, has 
 been found by the writer superior either for extracting or wherever 
 a local anesthetic is indicated, is as follows: 
 
 Acid, carbolic 10 gr. 
 
 Cocain hydrochlorid 10 gr. 
 
 Atropia sulphate 2 per cent, solution 10 min. 
 
 Nitroglycerin 1 per cent, solution 10 min. 
 
 Adrenalin chlorid Sol. (1 : 1000) 10 min. 
 
 Distilled water 2 oz. 
 
 After using and recommending it for nearly twenty years, the 
 writer has neither seen nor heard of any ill results following its use. 
 It is, however, wise to use this, and all allied preparations with 
 caution, using no more than is absolutely needed. 
 
 In making the application, only a very minute piece of cotton 
 should be used. A piece no larger than one-quarter the size of a 
 pin head is ample for the largest tooth. This is dipped in the anes- 
 thetic solution and then a slight excess of the cocain, which has 
 previously been finely powdered on a glass slab, is taken up on 
 the cotton and it is placed at the bottom of the cavity. 
 
 A piece of soft, unvulcanized rubber is then placed over it and 
 pressure brought to bear with an instrument which nearly fills the 
 opening. It must be remembered that in order to obtain perfect 
 
TREATMENT OF INFLAMED AND ACHING PULPS 45 
 
 results there must be a positive pressure, and if the instrument be 
 too large or too small it will not do the work as well. If a positive 
 pressure is obtained, it is not necessary to keej) it up longer than 
 from twenty to thirty seconds. The vulcanite and the pellet of 
 cotton are then removed, the opening dried, and the spear-pointed 
 drill is once more used. 
 
 If the tooth becomes sensitive again before the pulp is exposed, 
 the operation is repeated. It will be found, however, that, as a 
 general rule, with one or two aj)plications of the anesthetic, the 
 exposure can be obtained, without i)ain to the patient. After the 
 exposure has been made, the final ajiplication should be made 
 directly on the pulp, the pressure being kept up for about thirty 
 seconds, when it will be found that the \n\\\y has been completely 
 anesthetized and the i)uli) chamber can be opened and the pulp 
 removed. 
 
 It should be remembered that in using the anesthetic with 
 pressure, the pulj) is not devitalized, but simply anesthetized, and 
 if the operation of removing the pulp is long continued, sensation 
 may return. In multi-rooted teeth, when the canals are very 
 minute and difficulty is ex]>erienced in opening into them, sensation 
 may return to the pulp of one or two of the canals while the pulp 
 was being removed from the others. This necessitates a second 
 application. 
 
 If the tooth has been broken down by decay and a cavity exists 
 through which the pulp is accessible, this cavity may be utilized. 
 The disintegrated tissue, however, must first be thoroughly removed, 
 for its presence will hinder the action of the drug. The anestheti- 
 zing solution on a small pellet of cotton is then placed in the cavity, 
 and pressure applied as before described. 
 
 If the pulp cavity is freely exposed, the anesthetic may be 
 injected into it with a hypodermic syringe. This, however, is 
 more painful, and possesses no advantage over the method just 
 described. 
 
CHAPTER IV. 
 THE PULP CANALS. 
 
 POSITION OF THE PULP CANALS. 
 
 Before undertaking to remove the pulp from devitalized teeth, 
 the operator should have an accurate knowledge of the anatomy 
 of the teeth. He should know the number of roots which each 
 tooth should possess, and where to look for entrance to the canals 
 on the floor of the pulp chamber of a normal tooth, and should also 
 be able to form some idea of their approximate size. 
 
 Some of the canals are frequently very minute and difficult to 
 locate, and a knowledge of their normal position is helpful in 
 finding them. 
 
 All operations are more quickly and thoroughly done if the 
 operator works systematically, and by some well-considered rule. 
 This applies with much force to the operation of locating and 
 opening the pulp canals. 
 
 Opening into the Pulp Chamber of Molar Teeth. — Li enlarging the 
 entrance to the pulp chamber do not fear to make a large opening. 
 
 It is impossible to get into the different 
 canals in the molars, and cleanse them as 
 they should be cleansed, through a minute 
 opening in the crown of the tooth. A 
 large opening should be made through the 
 crown, and the pulp chamber opened to its 
 full size so that the entrance to every canal 
 is easily accessible. It does not weaken 
 the tooth to do this. As a chain is only 
 as strong as at its weakest point, so with 
 a tooth, and this point is where the pulp 
 chamber approaches the sides of the tooth (Fig. 18). 
 
 After drilling into the pulp chamber, the enamel at the entrance 
 to the cavity should be removed with a cross-cut fissure bur, but 
 the use of this bur should not extend to the pulp chamber. The 
 best instrument to enlarge this, is a large rose bur, passing it through 
 
 Fig. 18 
 
 Fig. 19 
 
POSITION OF THE PULP CANALS 
 
 47 
 
 the opening and under the ledge, or as it might be termed, the roof 
 of the pulp chamber, and pulling the bur toward the occlusal 
 surface (Fig. 19). 
 
 This should be continued until the explorer shows that the sides 
 of the cavity are flush with the sides of the pulp chamber and the 
 explorer slides smoothly into it. 
 
 A fissure bur, an inverted cone, or any square-ended instrument 
 should not be used in doing this work, as they are sure to strike 
 the sides of the pulp chamber, leaving ledges or grooves on which 
 the broaches will catch, and render the locating of the canals much 
 more difficult; whereas, by using round burs only, the floor of the 
 pulp chamber, is not marred, there will be no roughness to inter- 
 fere with the instrument, which will then much more readily find 
 the openings to the different canals. 
 
 1 
 
 Fig. 20. — a, Kerr Ijroaches; b, K<jir ctuinl files. 
 
 Locating the Pulp Canals of the Upper Molars. — As a rule, it is 
 more convenient to first locate the i)alatal canal in the upper molars. 
 This canal is much larger, and occupies a position which renders 
 it more easy of access than are the others, anfl it is rarely that there 
 is any trouble in locating it at once and removing the pulp. 
 
 The writer has found that the best instruments for locating the 
 canals are the short, knob-handled broaches of the Kerr or Downey 
 type (Fig. 20). These instruments are made of triangular steel 
 wire, twisted, and brought to a fine j)oint. They are much stronger 
 and are less liable to be broken than are the barbed broaches. 
 Then, too, being shorter, without l)arbs, and with just the right 
 degree of stiffness, they afhnit of a far more delicate sense of tone!) 
 than docs a long and very flexible instruniciit. 
 
48 THE PULP CANALS 
 
 When using these broaches, if conditions peimit, the rubber dam 
 should always be in place, but if this is not possible, the mouth should 
 be protected with napkins, so as to keep the parts dry, and also, 
 if the broach should slip from the fingers, to prevent its dropping 
 into the throat. 
 
 The palatal canal having been located, the next one to look for is 
 the anterior buccal. To reach this, the handle of the broach is passed 
 distally and palatally, reaching the point of the instrument far 
 forward toward the mesiobuccal corner of the tooth, and if the 
 pulp chamber has been carefully opened, there will be very little 
 difficulty in finding this canal. It sometimes happens that the 
 entrance to this canal is located so far mesially that it will be neces- 
 sary to cut entirely through the mesiobuccal corner of the tooth 
 in order to get free access to it. 
 
 There still remains the distal canal to be accounted for. If, 
 when the instrument is in the anterior buccal canal, it is slowly 
 withdrawn, sliding the point lingually through the groove in the 
 floor of the pulp chamber, as a rule the point will find the entrance 
 to this canal with but very little difficulty. These canals are often 
 very minute and extremely difficult to open. For this the Kerr, 
 or Downey, broaches are used, beginning with the small ones, and 
 working very carefully; using little or no force to push them into 
 the canals, but allowing them to work their way easily as the 
 broach is rotated. The sodium and potassium preparation may be 
 used to advantage in such cases, working it in with a broach. 
 Sodium dioxide is also used for this purpose, and will at times prove 
 quite effective. Again, a 50 per cent, solution of sulphuric acid 
 may be of assistance. A little of it, indeed, may be sealed into the 
 root and allowed to remain until a subsequent sitting, when it 
 frequently will have so softened the contents of the canal that the 
 broach will readily find its way to the end. 
 
 Fig. 21 will give a fair idea as to the position in which these 
 canals are generally found, the large palatal canal c being about in 
 the center of the palatal root and the anterior buccal canal a being 
 found very close to the anterior buccal corner. The distal canal h 
 will be found nearly on a line between the anterior buccal and the 
 palatal canal, or slightly distally to it, but very rarely at right 
 angles with the other canals. Occasionally, the two buccal canals 
 have a common opening into the pulp chamber (Fig. 22), and in 
 such cases, the entrance to the separate canals will be found just 
 a little below the pulp chamber floor. 
 
POSITION OF THE PULP CANALS 49 
 
 Occasionally, but \ery rarely, an upper first or second molar 
 will have but a single root. When this is the case, the canal will 
 be very large, the pulp chamber sloping from all sides toward the 
 center of the tooth, and the canal tapering to the apex (Fig. 23). 
 
 Again we may find one of these teeth which has two roots. When 
 this is the case the buccal canal is usually as large or even larger 
 than the palatal canal. If, on opening the tooth, the instrument 
 drops readily into the buccal canal, midway between the mesial 
 and distal sides of the tooth, and if it is very much enlarged through- 
 out its entire length, it is a fairly certain indication that there are 
 no more than two canals. If, on the contrary, this canal is very 
 much constricted, it indicates the existence of another canal. 
 
 o oj 
 b 
 
 Fig. 21 Fig. 22 Fig. 23 Fig. 2-4 Fig. 25 
 
 Where the molar has four roots, the two palatal canals will 
 generally be larger than the two buccal, and one will be almost 
 directly behind the other following the line of the arch (Fig. 24, 
 a and b), although neither of them will be as large as where there 
 is but a single palatal root. The two buccal canals will be about 
 in normal position (Fig. 24, c and d). 
 
 Locating the Pulp Canals of the First and Second Lower Molars.— 
 Normallx', the lower UKjlars have but two roots, almost invariably, 
 however, there are three distinct canals which must be cared for, 
 one in the distal, and two in the mesial roots. While in reality 
 there is but a single canal in this root, it is so constricted between 
 the buccal and lingual openings that this part of the canal is almost 
 obliterated, the s{)ace between the walls of the canal at this point 
 being so slight that there is, practically, no pulp tissue between 
 them (Fig. 25). 
 
 The distal canal r being the one most easily accessible, is naturally 
 the one first looked for. Tiiis canal being nnich larger than those 
 in the anterior root, and the position being favoral)le, it is readily 
 located and the jjnlp easily removed. 
 
 The canal next sought for is generally det('riniiie(| b.N the inclina- 
 tion f>f the tooth, if this be excessively to the lingual it would 
 4 
 
50 
 
 THE PULP CANALS 
 
 Fig. 26 
 
 Fig. 27 
 
 naturally be the lingual canal (Fig. 25, h), as this position of the 
 tooth renders it more easy to reach. In locating the canals in this 
 root, the rule in regard to the order in which they are opened is 
 not followed as closely as it is in locating the buccal canals in the 
 upper molar. At times, the buccal canal (Fig. 25, a) is more 
 quickly and easily located than the lingual. 
 
 Very frequently the distal slope of these roots is such that it 
 will be necessary to cut the mesial wall of the tooth almost to the 
 gum line in order that the instrument may follow 
 ; / the line of either the mesial or distal canals (Fig. 26) . 
 The buccal canal of the mesial root is the principal 
 offender in this respect, and it is sometimes neces- 
 sary to cut the mesio-buccal corner of the tooth 
 entirely away before an entrance into the 
 canal can be effected. 
 
 The mesial canals are frequently so 
 constricted and tortuous as to render it 
 extremely difficult to open them all the 
 way to the apex. At times it is necessary 
 to spend hours, or even days, toget these 
 canals properly opened and enlarged, but one of them, at least, 
 must be opened all the way to the end of the root. 
 
 These canals sometimes diverge buccally and lingually as they 
 leave the pulp chamber, and converge as they approach the apex, 
 having a common foramen (Fig. 27). 
 
 If it is practically impossible to entirely open but one of these 
 canals, and the other has been opened to within a very short dis- 
 tance of the apex, the little pulp tissue remaining in this small 
 space between the filling that is to be placed in the canal which has 
 been opened to the end of the root, and the filling which will be 
 placed as far down in the other canal as it can be placed (Fig. 27, a 
 and b), will hardly do any harm. 
 
 The canals, of course, must be perfectly sterilized, particular 
 attention being paid to the one which has not been opened entirely 
 to the apex. The canal from which the pulp has all been removed 
 is filled very carefully, making certain that it is filled all the way to 
 the end. The remaining canal, which has not been fully opened, 
 is saturated with a solution of zinc chloride, after which it is filled 
 as far as possible, so that only a little thread of coagulated pulp 
 tissue is left in the root. This is entirely cut off and isolated so 
 that the danger of subsequent trouble is very remote. If the 
 
POSITION OF THE PULP CANALS 51 
 
 operator desires, this canal can be filled with some mummify- 
 ing paste, but it is only in cases of this kind that such a filling is 
 indicated. 
 
 Occasionally these teeth, as in the case of the upper first and 
 second molars, may possess a greater or less number of roots than 
 normal, and there may be but a single root or there may be several. 
 There is rarely any trouble in opening the pulp canal of a single 
 rooted lower first or second molar, all the way to the end of the 
 root. As in the case of an upper molar, the pulp is always very 
 large and peg-shaped, so that it is easily removed. 
 
 The third molars or wisdom teeth are especially lacking in uni- 
 formit\- as to the number of their roots; they may have but a single 
 root or there may be many. These roots frequently converge and 
 may be fused together forming one large peg-shaped root in which 
 there may be several canals. These canals are frequently so small 
 and tortuous as to render it impossible to open all of them their 
 entire length. In such cases, the operator must be satisfied with 
 something less than the ideal, so far as filling them to the end is 
 concerned, but should make every effort to insure that they are 
 at least perfectly sterile. 
 
 It is this uncertainty in regard to their condition which some- 
 times renders them unserviceable as abutments for bridge-work. 
 In such teeth it would be impossible to give any fixed rule as to 
 opening of the canals and removing the pulp, except that the 
 pulp chamber should be fully opened so as to give free access to 
 all the canals which it is i)<)ssible to find. 
 
 Locating and Opening up the Pulp Canals of the Upper Bicuspids. — 
 The ui)per first bicuspid, is a double-rooted tooth with the canals 
 opening on the buccal and lingual side. The canals of these roots 
 are sometimes quite constricted, and require considerable time to 
 open them all the way to the end. With a little perseverance and 
 the use of the sodium and potassium, or sulphuric acid, this can, 
 however, generally be accomplished. 
 
 Occasionally the root has a very sharp curve near the apex. 
 Indeed, it is at times bent almost, if not cjuitc, to a right angle with 
 the rest of the root. In such cases it will be impossible to remove 
 all of the i)ulp tissue. As much as possible is taken away with the 
 broaches, using the sodium and i)otassium, or the sodium dioxide, 
 and then trust nnist be placed in antiseptic; treatment to prevent 
 future trouble. There are times when it may be advisable to ampu- 
 tate these curved root ends, before using the teeth as abutments. 
 
52 
 
 THE PULP CANALS 
 
 The upper second bicuspids sometimes show exactly the same 
 conditions as are to be found in the mesial root of the lower molars, 
 a single root, but practically two canals, which should be treated 
 in a similar manner to those of the lower molars. These canals 
 may be entirely separate and present all the appearance of a first 
 bicuspid, but if they are opened all the way to the end, it will be 
 found that they unite at the apex in one common foramen, and if 
 one of the canals be filled, the filling will be forced a little distance 
 up into the other canal. 
 
 A two-rooted second bicuspid occasionally is found, but this is 
 rare and need not be especially considered, as the treatment would 
 be the same as for the first bicuspid. 
 
 Fig. 28 
 
 Fig. 29 
 
 Locating and Opening up the Pulp Canals of the Lower Bicuspids 
 and Anterior Teeth. — The lower bicuspids have but a single root, 
 and the pulp is approached directly through the center of the cusp. 
 
 All of the six anterior teeth, both upper and lower, are opened 
 from the lingual side, as near the center as possible, and it is very 
 rarely that any trouble will be encountered in removing the pulp 
 and thoroughly sterilizing the canals. 
 
 X-rays in Pulp Canal Work. — The discovery of the Roentgen rays 
 and the introduction of the .r-ray machines has been of great value 
 to the dentist, and especially so in pulp-canal work. It has enabled 
 him to open up the pulp canals, and to work with almost absolute 
 certainty, where, before its introduction, he had been working 
 in the dark, and pulp canal operations were, to a certain extent, 
 mere guesswork. 
 
 In all cases where there is the least uncertainty, and in fact, in 
 treating any of the teeth, and especially those having more than a 
 single root, it is advisable to have an .r-ray taken before beginning 
 operations. The film will show at a glance the number, position, 
 
POSITION OF THE PULP CANALS 
 
 53 
 
 and approximate length and shape of the roots, and the location 
 of the canals, thus enabling the operator to work much more 
 quickly than he otherwise could (Fig. 28). 
 
 In difficult cases, after having opened and enlarged the canals, 
 it is an excellent plan to insert fine wires to the depth to which they 
 have been opened, and then have another ;r-ray taken to verify 
 
 Fig. 30. — Wires in canals showing dis- 
 tal canal perfectly opened to apex, but 
 wire in mesial root shows side of root 
 slightly penetrated anterior to the 
 canal. 
 
 Fig. 31. — Upper first Iiicuspid show- 
 ing buccal canal entirely filled and pal- 
 atal canal only upper third filled, the 
 balance of canal being used to insert a 
 post for a crown. 
 
 the work (Fig. 29). The illustration shows this very clearly, and 
 we can appreciate the value of these pictures as an aid in this 
 work. Many times, as in Fig. 30, the second picture will show that 
 a canal, in which it was thought that ^ 
 the work had been perfectly done, had 
 not l)een opened nearly to the end, and 
 had it been filled without carrying the 
 work further, might have resulted in 
 serious trouble. At times it is well to 
 submit the patient to a third exposure 
 before proceeding to fill the canals. 
 It is also often advisable in difficult 
 cases, and at all times a great satis- 
 faction, to know whether our work 
 has been perfectly done, or otherwise. 
 An ar-ray taken after the roots have 
 been filled will readily show this 
 (Fig. 31). 
 
 The use of the .r-ray is often a great saver of time. At times the 
 writer has worked for hours over a tooth, endeavoring to open up 
 certain canals, but lias failed until an .r-ray of the root has been 
 
 Fig. 32.— The above r:i(lii)Kiaph 
 shows .a sharp turn biu^kward of the 
 mesial root of the lower first molar 
 and the canal only partly (illcd. 
 With the aid of the dim, it was 
 possible to open up both roots 
 easily and (|uickly all the way to 
 the apex. 
 
54 
 
 THE PULP CANALS 
 
 taken. This has shown, perhaps, a curve in the root which neces- 
 sitated the cutting away of a large portion of the mesial wall of the 
 crown before it was possible to get into the canal more than a short 
 distance, but after securing the films, he has been enabled to com- 
 plete the work and open the root all the way to the apex within a 
 very short time (Fig. 32). 
 
 The value of the a;-ray to the dentist cannot be overestimated, 
 and those who are taking advantage of it are doing far better work 
 than it would be possible for them otherwise to do. A chap- 
 ter on this work has been written by Dr. Frederick K. Ream, 
 of New York, and will prove very instructive reading. 
 
 REMOVING THE PULP AND CLEANSING THE PULP 
 
 CANAL. 
 
 The Donaldson canal cleansers, and instruments of that 
 type are best suited for the purpose of removing the pulp 
 where the canal is sufficiently large to admit of their 
 entrance (Fig. 33). These broaches are barbed on all sides, 
 the barbs being cut around the shaft following the direction 
 of the thread of a right-hand screw. Such instruments 
 
 should be used with care, being 
 necessarily very delicate, as in 
 
 ] barbing them, the broach is 
 
 cut partially through, weaken- 
 ■ ing it to a great extent. 
 
 The broach should be held 
 in the fingers lightly and 
 sholud never be forced. In 
 entering the canal the broach 
 is rotated slightly to the right, 
 allowing it to be drawn into 
 the pulp tissueand after enter- 
 jljllj^ llll ing to a sufficient depth may 
 
 I 'Plil Hi be withdrawn with the pulp, 
 
 Fig. 33.— Donaldson's pulp canal cleansers. Or a portion of it adhering tO 
 
 it. Never allow the broach to 
 become jammed. Keep touching lightly, twisting it the least bit 
 with each forward motion until it catches a little, then with- 
 drawing it, and continue these movements until the apex is 
 reached. Should the broach become jammed, it is released by 
 rotating carefully to the left. 
 
REMOVING PULP AND CLEANSING PULP CANAL 55 
 
 Where the canals are very small, the Kerr or Downey broaches 
 can be used to enlarge the canals and remove the pulp, beginning 
 with the smaller broaches and working up to the larger. While 
 these broaches are much stronger than are the Donaldson, care 
 must be exercised in their use, as the finest of them are very 
 delicate. 
 
 Where the canals are so minute that trouble is experienced in 
 opening them, even with the finest broaches, the use of sodium 
 and potassium, or sodium dioxide, is indicated, the soldium and 
 potassium being preferred. A small amount of the preparation 
 is carried to the canal on the broach and worked into it with 
 a pumping and rotating motion. This will facilitate matters 
 and tend to enlarge the canal slightly, so that the broach may 
 readily follow it. 
 
 At times a drop of 50 per cent, sulphuric acid in the canal will 
 very materially assist in the work, and sometimes if a little of the 
 acid is sealed in the canal and left there until a subsequent visit 
 of the patient, it will frequently enable the remainder of the canal 
 to be easily opened. 
 
 The openings from the canals into the pulp chamber are generally 
 somewhat constricted, as shown in Figs. IS and H). They should 
 be slightly enlarged at this point with a Gates-(ilidden drill. They 
 are thus not only rendered easier of access to the broach, l)ut the 
 removal of the ])uli) is also facilitated. 
 
 Instruments must be Perfectly Sterile. — It is to be understood that 
 in all of these operations, the instruments nuist be thoroughly 
 sterilized before using, and sometimes during the operation. This 
 is best done in superheated steam or by boiling. The former is 
 by far the most thorough and efficient of any method which can be 
 employed. Fig. 'M shows an apparatus for sterilizing by steam. 
 The instruments are placed in a tray, which is i)ut in a highly 
 heated cxlinder. A little water is then injected into the cylinder 
 and is instantl\' converted into steam of several hundred degrees 
 of heat and the instruments are thoroughly sterilized in a very 
 f(nv moments. 
 
 {''orrnaJin is also a very good sterilizing agent, but it is better to 
 use a stronger solution than is generally employed for this purpose. 
 A solution of Formalin diluted with water alone will corrode the 
 instruments so as to rnin them in a short time, bnt a solution com- 
 posed of one part formalin to thre(; parts of a saturated solution 
 of l)i<;irl»f)nate of soda, may be safely nsed and is very eiVective. 
 
56 
 
 THE PULP CANALS 
 
 Instruments placed in this solution and left for several days will 
 remain as bright and clean as when first put in. 
 
 The canal should first be cleansed mechanically, the sides being 
 thoroughly scraped with the barbed cleansers so as to remove every 
 particle of pulp tissue that it is possible to reach. 
 
 At all times, after the pulp has been removed and the canals 
 opened, it is well to use the sodium and potassium. A platinum 
 point is best suited for this purpose, although twisted broaches of 
 the Keer or Downey type may be used. A small portion of the 
 sodium and potassium is taken up on the instrument, carried into 
 the canal and worked in as previously described. This will have 
 a tendency to destroy any organic matter remaining in the canal 
 and render it perfectly sterile. 
 
 Fig. 34 
 
 The sodium and potassium may be used freely, but its use must 
 not be carried to an excess, as an excessive use of this agent has a 
 tendency to burn the life out of the tooth structure and render 
 it brittle. 
 
 After the canals have been opened to the end of the roots, those 
 which are very minute should be enlarged sufficiently^ to allow the 
 filling to be properly inserted. This can be done with the canal 
 files by working them back and forth in the canals until they are 
 of the desired size. The Donaldson canal cleansers can be used, 
 but greater care must be exercised, as they are more easily broken. 
 
 When the canals are not to be filled at the time of the removal 
 of the pulps, a small portion of the sodium and potassium may be 
 sealed in the canals until a subsequent sitting. 
 
 This delaying the completion of the work, to a subsequent sitting, 
 applies especiall}^ to the multi-rooted teeth, where the canals are 
 
TENDERNESS AFTER REMOVAL OF THE PULP 57 
 
 very minute, and much difficulty has been experienced in opening 
 them. 
 
 In the single-rooted teeth, and also in the larger canals of the 
 molars, where there has been no difficulty in opening them all the 
 way to the end of the root, the work of devitalizing and removing 
 the pulp, the cleansing and sterilizing of the canals, and the filling 
 of the root should be completed at one sitting. 
 
 Where the work has been delayed, when the patient returns and 
 the tooth is opened, the use of the sodium and potassium is repeated, 
 but only a moderate quantity should be used. The canal is then 
 thoroughly waslied with a solution of bichloride of mercury and 
 peroxide of hydrogen, the solution being composed of one and 
 tliree-quarter grains of bichloride of mercury to two ounces of 
 peroxide of hydrogen. This makes a bichloride solution of a 
 strength of about one to five hundred and will insure the 
 thorough sterilization of the canals. This solution should not be 
 used, however, until just previous to filling the roots. If it is 
 sealed into the canals, it is apt to cause the patient pain, which 
 may continue for some time. After having used the bichloride 
 solution, the canals are wiped out and thoroughly dried with 
 alcohol preparatory to filling. 
 
 Where the pulp has been removed and the canals are to be filled 
 at the same sitting, the operator should proceed in the same manner, 
 using the sodium and potassium thoroughly, and then washing the 
 canals with the bichloride solution and drying them. 
 
 TENDERNESS OR SENSITIVENESS AFTER THE REMOVAL OF 
 
 THE PULP. 
 
 Tenderness or sensitiveness after the removal of the i)ulp may 
 be due to a minute portion of pulp tissue missed by the broaches, 
 and still adhering to the walls of the canal. This is especially likely 
 to occur when the canal is very much flattened, and the puli) is 
 compressed to a knife-like edge, generally on the lingual or 
 palatal sifle fFig. 3.5). This is most likely to occur in the 
 cusjiids and lower bicuspid teeth. 
 
 Occasioriallv, when a patient returns to have the pulp 
 
 *' I'll! '**' 
 
 canal filled, on a visit subs('(|nciit to that on wliicli the i)ulp 
 was removed, the tooth will be extreiriely sensitive. When such 
 is the case, it is (piite likely that a small portion (tf |)nl|) tissue 
 still remains in the eanal. 
 
 (!) 
 
58 
 
 THE PULP CANALS 
 
 Sometimes the pain will cease at once on thrusting a barbed 
 broach quickly to the end of the root and twisting it. Generally, 
 however, the sodium and potassium preparation will enable us to 
 remove this thread of sensitive tissue. 
 
 In obstinate cases it may be necessary to use a little cocain, or 
 local anesthetic, pumped as far into the canal as possible, before 
 being able to remove the cause of trouble. 
 
 ENLARGING THE PULP CANAL. 
 
 In enlarging the canals for the reception of the post, none but safe- 
 ended instruments should be used. Instruments such as rose burs, 
 spear-pointed drills, fissure burs and those of a similar character, 
 should never be employed for this purpose, as they will not follow 
 the canal, and there is danger of perforating the sides of the root, 
 and causing trouble for both the patient and the operator. 
 
 Determining the Length of the Root. — When enlarging the pulp 
 canals it is important to first determine the exact length of the 
 root, so as to know just how far it will be safe to go and how long 
 a post can be used. The Kerr broaches or canal files, or instruments 
 of a similar type are suitable for this purpose, beginning with a very 
 fine one, and carrying it slowly to the apex, first cautioning the 
 
 Fig. 36. — Gates-Glidden nerve-canal drills. 
 
 patient to give notice on the first sensation of pain, or of feeling the 
 instrument at the apex. After testing carefully a number of times 
 to be certain that no mistake has been made by the patient, the 
 depth to which the instrument has gone can be registered by pushing 
 a small piece of rubber dam over the broach and pressing it down on 
 the face of the root, or the incisal edge of the tooth, while the point 
 is at the apex. This gives an exact measure of its length. The larger 
 broaches can then be used, but only to within about one-eighth 
 of an inch, or a little less, from the apex. Gates-Glidden drills, 
 Fig. 36, of different sizes, beginning with the smallest and ending 
 with the largest, can then be used to the same depth. 
 
 These latter instruments are safe-ended, having a round, smooth 
 guide point, which will follow an opening, but will not cut at the 
 
ENLARGING THE PULP CANAL 
 
 59 
 
 end (Fig. 36, a). The instruments should not be forced at all, 
 but should be allowed to work their own way into the canal, with- 
 drawing frequently to clear them, and just touching lightly until 
 the desired depth has been reached. 
 
 These instruments were first made with the shank tapered, with 
 the lightest and weakest part close to the head (Fig. 36, b) and if 
 broken, only the head of the instrument remained in the canal. It 
 was very difficult, at times, indeed, impossible, to remove them. 
 Later they have been made tapered in the opi)osite direction, so 
 that the lightest and weakest part is far uj) on the shank, and if 
 broken at this i)oint (Fig. 36, c) the part left in the root can be 
 removed with comparative ease. When pur- 
 chasing instruments it is wise to see that they 
 are of the later ])attern. 
 
 The Gates-Cilidden drills are followed with 
 reamers of suitable size, bearing the writer's 
 name (P'ig. 37), enlarging the canal sufficiently 
 to take a pin or a tube of the size desireil. 
 These instruments are also safe-ended, having 
 a smooth-rounded guide point the same as the 
 Gates-Glidden drills. They will follow the 
 canal and enlarge it, but will not cut at the end, 
 and in using them there is not the slightest 
 danger, hardly a jjossibility, with ordinary care, 
 of perforating the root. 
 
 The manner in which the canal of a tooth 
 is enlarged depends upon the style of a crown 
 that is to be used. 
 
 Enlarging Pulp Canals for Richmond Crowns. — Where a Uichinond 
 crown, or a crown with porcelain facing and a, solid metal back is 
 to be used, after the canal has been opened, the reamer is i)artly 
 withdrawn and sloi)ed lingually, enlarging the canal at the gingival 
 end of the root in that direction (Fig. 3S, a and h). The object of 
 enlarging the canal in this maimer is to allow jjlenty of room 
 labially, to place tlu; facing. 
 
 if, in any of the six anterior teeth, the canal is sinii)ly enlarged 
 on its original line, the facing will come directly over the ()i)ening. 
 Tliis would necessitate cutting the i)in olV finsli witli the floor 
 of the cap, in order that the facing might set flat on tUv floor 
 (Fig. 39j. 'i'he aternative wonhl be to pursue another method. 
 This consists of grinding the liiignal side of the fiieing, toward the 
 
 Fi(i. 37.— Root- 
 reamers. 
 
60 
 
 THE PULP CANALS 
 
 gingival end, and curving it outward so that only a small portion 
 of it rests on the extreme labial side of the cap. The backing is then 
 made to conform with this, coming down flush with the floor, thus 
 making room enough to engage the pin in the solder (Fig. 40). 
 
 In the first method, by grinding off the pin, and setting the facing 
 fiat on the floor of the cap, the crown would be rendered very weak, 
 as the only attachment the post would have would be to the thin 
 
 Fig. 38 
 
 Fig. 39 
 
 Fig. 40 
 
 Fig. 41 
 
 floor of the cap, and but little force would be necessary to tear it 
 away (Fig. 39). By sloping the canal lingually and then giving 
 the post a slight bend in that direction, it will leave plenty. of room 
 labially to place the facing in its proper position without weakening 
 in the least the attachment of facing or post (Fig, 41). 
 
 The objection to the second method, that of grinding the facing 
 labially, carrying the backing down to the point of contact with 
 the floor of the cap, and filling in this space with solder, is that it 
 
 Fig. 42 
 
 Fig. 43 
 
 Fig. 44 
 
 too often makes the work conspicuous. The mass of gold being 
 carried so near to the labial face of the tooth renders it visible. 
 It will glitter, or cast an ugly dark shadow between the teeth, and 
 be very unsightly. This is especially true if the teeth are quite 
 fan-shaped, with broad spaces between them near the necks and 
 applies particularly to the upper six anterior teeth (Fig. 42) . There 
 are times when the facings may be gound in this manner, as in the 
 
ENLARGING THE PULP CANAL 
 
 61 
 
 case of the bicuspids, or more rarely, even in the cuspid, where they 
 are broad at the neck, but orchnarily it is not advisable. 
 
 Enlarging Pulp Canals for an all Porcelain or Downie Crown. — Where 
 an all i)orcehun crown or a Downie crown is to l)e used, either 
 building up the entire crown with porcelain, or using a facing and 
 building up the lingual portion only, the canal is simply enlarged 
 in its original direction so that the pin will set directly in the center 
 of the tooth. This applies especially to the upper anterior teeth 
 where there is but little force exerted except in an outward direc- 
 tion. The reason for this is as follows: Porcelain is a very fragile 
 material and its strength is only in proportion to its bulk. By 
 having the post in the center of the root, and cutting a groove on 
 the lingual side of the facing between the tooth pins (Fig. 43), so 
 that the post will set in nearly flush with the back of the facing, 
 it permits a greater bulk of porcelain lingually to the post, thus 
 giving increased strength to the crown (Fig. 44). 
 
 If the post is allowed to come lingually, as in the case of a Rich- 
 mond crown, it would permit of but little porcelain back of it, 
 particularly if the bite was very close, thus rendering it very much 
 weaker than it would otherwise be. This does not apply so par- 
 ticularh' to the lower anterior teeth as with them the greater 
 pressure is inward. 
 
 Fig. 45 
 
 Fig. 4() 
 
 Wlicii j)lacing a Richmond or a porcelain crown on an upjxT 
 first bicusj)id root, it is very rarely that there is any necessity for 
 using more than one of the canals for the post and the palatal canal 
 should always be chosen. In mastication, the force exerted on 
 these teeth is always upward and outward (Fig. 45), consccjuentiy 
 if the post is well anchored into the |>alatal root, there will be no 
 necessity for a post in the buccal root, for the reason that the direc- 
 tion of force is such that the crown will always be forced tightly 
 
62 THE PULP CANALS 
 
 against the root on the buccal side, and the post in the palatal canal 
 will bind it firmly to the root at that point (Fig. 46). The only 
 exception to this is where the teeth have extruded somewhat, and 
 the roots are much decayed far down under the gum. From the fact 
 of their being so short, it might at times be advisable to utilize 
 both canals in order to give the necessary retention, 
 
 FILLING THE PULP CANAL. 
 
 There are many different methods and materials used for filling 
 pulp canals. Satisfactory and permanent results, however, depend 
 fully as much on the manner in which these fillings are inserted as 
 it does on the materials which are employed for the purpose. 
 Among these we find gutta-percha points, oxychloride of zinc, gold, 
 chlora-percha, paraffin and even wood points. It is probable that 
 gutta-percha and oxychloride of zinc are more extensively used 
 than are any of the others. 
 
 Gutta-percha Points. — Of all materials, the writer believes that 
 the very best results are obtained from using gutta percha points. 
 He also believes that a filling of this material is much more easily 
 inserted, and that it is possible to carry the filling to the extreme 
 end of a very fine canal with a great deal more certainty than can 
 be done with any other material. 
 
 As a preliminary to the operation, it is understood that the 
 rubber dam is to be applied, if the conditions will permit, and if not, 
 napkins should be used to keep the mouth as dry as possible. 
 
 A point is selected of a size corresponding to the canal which is 
 to be filled, and placed for a time in the bichloride solution to 
 sterilize it. It is then dried on a napkin and attached to 
 the end of a canal-plugger by heating the point of the instru- 
 ment. The canal, being thoroughly cleansed and dried with 
 alcohol, is slightly moistened with eucalyptus oil, carrying it into 
 the root on a small wisp of cotton twisted around a broach, or 
 between the points of a pair of fine dressing pliers. The gutta- 
 percha point is first dipped into the oil of eucalyptus and then 
 just the tip of it into aristol, or iodoform, after which it is placed 
 in the canal and worked into it with a slight pumping motion, 
 carrying it farther and farther, as the oil softens it, until the extreme 
 apex is reached, which, in the majority of cases, can be told by the 
 patient wincing. If the point has not become loosened from the 
 plugger by this time, it can be freed by rotating the plugger a 
 
FILLING THE PULP CANAL 63 
 
 little, after wliieli the point is packed tightly into the end of the 
 canal. 
 
 It is not objectionable to see the patient wince a little during the 
 operation of filling a pulj) canal. In fact, it is rather desirable, as 
 it is a very good, though not an infallible indication that the end 
 of the root has been reached. 
 
 Chloroform may be used in place of the eucalyptus oil, injecting 
 it into the root and working the point with a pumping motion the 
 same as where the oil is used. It is not probable, however, that 
 it will make as perfect a filling as where the eucalyptus oil has 
 been used. The chloroform evaporates or penetrates the tooth 
 structure ^'ery rapidly, so that the softened gutta-percha soon 
 becomes a sticky mass adhering to the side of the canal, and has a 
 tendency to ])re^'ent the point going freely to the apex. Then, too, 
 the rapid evaporation of the chloroform is liable to cause a shrinkage 
 of the gutta-percha, so that after a time it ceases to fully fill the 
 canal. 
 
 The eucalyptus oil is much to be preferred to chloroform, as it 
 is of a healing and soothing nature, besides possessing antiseptic 
 properties which persist in the canal for many years. It is also a 
 slight sohent of gutta-percha, and makes an excellent lubricant, so 
 that the point slides into the canal freely. 
 
 The canals are filled with the gutta-percha to within about one- 
 sixteenth of an inch of the floor of the pulp chamber. The part 
 which remains unfilled is then carefully cleansed with alcohol and 
 dried thoroughly, after which it is filled with oxychloride of zinc. 
 
 Where it is intended to enlarge the canal in order to insert a 
 post as an attachment for a crown, the canal may be enlarged at 
 once, with a reamer, to the desired size and depth, enlarging it to 
 within about one-eighth of an inch, or a little less, from the apex, 
 before filling. 
 
 A very short gutta-perdia point is then used, dipping 
 it in eucalyptus and aristol, and just filling the apex, i)ack- 
 ing it tightly against the shoulder left by the reamer (Fig. 
 47j. 'J'he canal is then wijx'd dry and the gutta-percha j,^^ ^^ 
 covered liglitl\' with oxychloride of zinc. 
 
 Filling Pulp Canals with Enlarged Foramen.- Where the aj)ical 
 foranicM is very much enlarged, as it will be in the case of an unde- 
 vclojx'd tooth, gutta-|)ercha is the only suitable material for filling, 
 and care must be used so that the filling is not forced beyond the 
 apex. The exact length of the root is first ascertained by passing 
 
64 
 
 THE PULP CANALS 
 
 Fig. 48 
 
 a hooked broach through the enlarged opening and marking the 
 length with a small piece of rubber placed over the broach (Fig. 
 48, b). 
 
 It is always advisable to have at hand a series of different sized 
 canal pluggers, from which one is selected which will pass into the 
 canal only to within about one-eighth of an inch, 
 a b c or a little less, from the end (Fig. 48, a). This 
 can be told by placing it alongside of the hooked 
 broach used for measuring its depth. A blunt 
 gutta percha point is now selected, slightly larger 
 than the end of the canal plugger and a little 
 shorter than the distance from the end of the 
 plugger to the end of the canal (Fig. 48, c). This 
 is attached to the end of the plugger, and is then 
 dipped in eucalyptus and aristol and pressed firmly 
 in place at the end of the root, the canal hav- 
 ing been previously dried. The plugger is then 
 loosened by rotating, after which the canal is 
 washed and dried w^ith alcohol and the gutta-percha is covered 
 over lightly with oxychloride of zinc. 
 
 The diameter of the gutta-percha point having been somewhat 
 greater than that of the canal to be filled and also slightly shorter, 
 it packs very tightly in place as far as the plugger point will carry 
 it, and at the same time the contraction of the canal elongates it a 
 little, so that the apex is perfectly closed. Then too, the plugger 
 being of large size, renders it impossible for the filluig to be forced 
 beyond the point desired, and through the foramen where it might 
 act as an irritant. 
 
 A plugger of a smaller diameter than the apical foramen should 
 never be used in filling these canals. An accident or a sudden 
 movement of the patient might cause the filling to be forced through 
 .the end of the root, with no possibility of removing it. 
 
 If the entire length of the canal is to be filled, the operation will 
 be very similar to the one described. The size of the foramen is 
 ascertained with a suitable plugger. The plugger used for filling 
 should be just large enough so that it will pass into the opening of 
 the canal from the floor of the pulp chambers, not much more than 
 one-sixteenth of an inch. The size and length of the gutta-percha 
 point is determined from these two pluggers and the hooked broach. 
 It is made of a slightly larger diameter and a little shorter than the 
 canal. After it has been dipped in the eucalyptus oil, it is packed 
 
FILLING THE PULP CANAL 65 
 
 tightly in place as far as the plugger point will carry it. The one- 
 sixteenth of the canal remaining unfilled, is covered with oxy chloride 
 of zinc. 
 
 Where chlora-percha is used as a filling, a little iodoform or 
 aristol should first be put into the canal, after which the chlora- 
 percha is pumped in with a broach, a fresh supply being added as 
 the chloroform evaporates. 
 
 When it is carried well into the canal, a gutta-percha point may 
 be forced into it, but it is questionable if this will make as perfect 
 a filling as a gutta-percha point, as there is necessarily a much 
 greater shrinkage where chloroform is used than there can be with 
 only a \'ery small portion of the oil of eucalyptus. 
 
 Oxychloride of zinc should never be used for a filling where 
 the foramen is very much enlarged, and it is probable that 
 in all cases, the gutta-percha point is to be preferred. Zinc 
 chloride is a strong irritant, and if a slight amount is carried be- 
 yond the apex and into the tissues, it may set up an inflammation 
 difficult to control, causing considerable pain and discomfort to 
 the patient. 
 
 On the other hanrl, gutta-percha is an inert substance, and if a 
 little is carried beyond the apex, the irritation caused by its presence 
 is slight, and will soon pass away. 
 
 Another objection to the use of oxychloride of zinc as a canal 
 filling, especially in any of the teeth anterior to the molars, is the 
 difficulty of opening the canals so filled for the reception of a post, if 
 at some futnre time it should become necessary to crown the roots. 
 This difficulty, however, may be overcome to a certain extent, if 
 after the canal has been filled with the oxychloride of zinc cement, 
 before it begins to harden, a gutta-percha point is inserted and 
 forced as far toward the apex of the root as possible. Indeed, it 
 is a wise precaution to do this in all cases, when using oxychloride 
 of zinc as a canal filling. 
 
 Filling Pulp Canals with Paraffin. — Paraffin is also advocated and 
 used by some for filling pulp canals. The canals are thoroughly 
 dried and a little iodoform or aristol is sifted into the openings of 
 the canals. The paraffin is then carried into the canals with a fine 
 heated broach. It is claimed that this makes a good root filling, 
 especially in the lower teeth, but the writer does not recommend 
 its u.se." 
 
66 THE PULP CANALS 
 
 TREATMENT OF PERFORATED ROOTS. 
 
 A perforated root is a complication frequently encountered, and 
 unless slight and favorably located it is at times quite difficult for 
 the operator to decide what is best to do. If the perforation is 
 large; if there has been much mutilation of the root or irritation of 
 the soft tissues, or it has been of long standing, it may, perhaps, be 
 best to remove the tooth or root. Each case, hoM^ever, must be 
 decided upon its own merits, with a strong leaning toward the 
 forceps in all doubtful cases. 
 
 On the other hand, if the tooth or root is especially valuable to 
 the patient, and conditions are favorable, it is best to make the 
 effort, as it is sometimes possible to restore even a badly perforated 
 root to a healthy state with a fair chance of its remaining so. 
 
 Where the perforation is recent, and there has not been much 
 mutilation of the tissues, it can nearly always be treated and 
 properly filled so as to render the tooth serviceable. 
 
 In all of these cases unless the perforation has been very recent 
 it is quite likely that the soft tissues have grown into the cavity. 
 This intruding tissue must first be removed by excision, or it may 
 be cauterized with trichloracetic acid, carbolic acid, or iodin. Where 
 the size of the growth is not great, the opening may be cleared by 
 packing the cavity tightly with dry absi?rbent cotton. This will 
 expand as it becomes moist, and will force the gum tissue out. 
 At times gutta-percha may be used for this purpose, the cavity 
 being tightly packed. 
 
 There are different materials which may be used for closing 
 these perforations, such as gold, gutta-percha, oxyphosphate of 
 copper, thin platinum or tin foil burnished over the perforation 
 and then covered with one of the above, and lastly, copper amalgam. 
 
 In the experience of the writer copper amalgam has proven to 
 be the most satisfactory material which can be used in such cases. 
 The tissues seem to take more kindly to it than to any of the others, 
 and if the work is done carefully, there will be practically no irrita- 
 tion. Many times, where everything else has been tried and failed, 
 copper amalgam has proved most effective. 
 
 Manner of Treating Perforated Pulp Chambers or Canals. — The parts 
 are first thoroughly sterilized and then a little adrenalin chloride 
 may be left in the cavity for a few minutes, to check any hemorrhage 
 or flow of serum, after which the cavity is thoroughly dried with 
 alcohol. 
 
TREATMENT OF PERFORATED ROOTS 67 
 
 Where there is a ^•e^y hirge perforation in the floor of the pulp 
 chamber it is well to lay a little piece of platinum in the form of 
 a cross over the opening, as in Fig. 49, so as to prevent any excess 
 of the amalgam from being forced through. This is then covered 
 with the copper amalgam, using a broad faced burnisher and spread- 
 ing it carefully over the floor of the pulp chani})er, the sides of 
 which have been ])reviously undercut slightly so as to hold it. The 
 mercury should be well squeezed out of the amalgam before puttmg 
 it into the ca\'ity. 
 
 Fig. 49 
 
 The canals should also be kept free from the amalgam. If the 
 perforation extends near them, pins, which have been oiled or 
 wiped with vaseline or cocoa butter, can be placed in the entrance 
 (jf the canals, and the filling smoothed into place, after which the 
 pins may be removed, leaving the entrances to the canals free (Fig. 
 50). The copper amalgam at this stage being very soft, and also 
 very slow setting, the teeth should be carefully i)rotected and any 
 further operation in the pulp chamber or canals should be postponed 
 to a subse(|uent sitting. The amalgam may be covered lightly 
 with temporary stopping, care being exercised not to use pressure 
 enough to force any excess through the perforation. 
 
 Where the ])erforation is at the end of the root, it may be filled 
 with a gutta-percha i)oint, in the manner described in treating of 
 filling pulp canals with enlarged foramen, or packed with coi)i)er 
 amalgam, using a large instrument which will penetrate the root 
 only to within about one-eighth of an inch of the apex. 
 
 Where there has been much inflammation, a dressing on cotton, 
 comjK)sed of one of the essential oils and iodoform or aristol or 
 tricresol and formalin may be kept in the canal until the soreness 
 has passed away, when the root may be filled as already described. 
 An excess of the oils or tricresol and formalin should be avoided, 
 or it may act as an irritant. After dii)i)ing the cotton in the litjuid, 
 it should be sciuee/ed in the folds of a napkin bd'ore a|)plying. 
 
 Where the perforat i(»ii is at the side of the root, if it be not 
 
68 THE PULP CANALS 
 
 far below the gum line, a small, thin, flat-ended instrument can 
 often be passed under the gum and held to the side of the root, so 
 as to cover the opening. With this in place, the amalgam can be 
 packed into the perforation and against the instrument. When the 
 opening is so located as to be inaccessible from the outside, a trial 
 plug should be made for the perforation, showing the size of the 
 opening and also giving an idea as to the amount of material which 
 will be necessary to fill it. For this purpose, a piece of base plate 
 gutta-percha is used, passing it into the canal, packing it carefully 
 into the opening and forcing it through to the outer wall of the 
 
 root. This plug is then removed and will give the 
 A size and shape of the perforation (Fig. 51). A little 
 w adrenalin chloride may be left in the cavity while 
 
 the filling is being made ready. 
 
 A small piece of copper amalgam, slightly larger 
 
 than the trial plug is now prepared. The cavity 
 
 thoroughly sterilized and dried, and the sides of 
 the opening grooved or slightly roughened, so as to hold the filling 
 in place. The material is then packed into place and smoothed over 
 carefully, so that no excess material is forced through the opening 
 and into the tissues. It is then left to harden. 
 
 If it is desired to use gutta percha to close the perforation, the 
 trial plug can be sterilized and shaped so that it will reach not quite 
 to the outer wall of the root, leaving a slight excess on the inner 
 side. The plug is then lightly fastened to the end of the instrument 
 and placed in the opening and packed flush with the canal wall. 
 
 It should be remembered that if the root is to be banded, the 
 amalgam should be kept within bounds so that it will be impossible 
 for it to come in contact with the band. 
 
 FRACTURED ROOTS. 
 
 This is a troublesome complication and of somewhat frequent 
 occurrence. It is often difficult to decide whether a root which has 
 been split can be saved or should be extracted. The fracture of 
 a root is often brought about by placing upon it an artificial crown 
 without banding or protecting the root, and more frequently occurs 
 in the incisors and bicuspids, than in the other roots. 
 
 In the majority of cases, where there is a bad fracture of long 
 standing, and where the broken parts are widely separated, it will 
 be necessary to remove the root, but sometimes it can be made to 
 
FRACTURED ROOTS 69 
 
 do good service, even when it has been spHt all the way to the 
 apex. As an example an upper central incisor may be taken 
 (Fig. 52). If the fracture is recent, and the 
 parts are not much separated; so that the gum 
 tissue has not crowded in between the broken 
 parts, they can be brought together, and by 
 crowning the root properly, it can be made to 
 last for a number of years. 
 
 As a preliminary, any tissue which may have 
 worked in between the separated parts should ^'*^" ^^ ^^^' ^^ 
 be carefully removed and the opening washed 
 out and thoroughly sterilized. To facilitate this, an instru- 
 ment should be placed in the split and the broken halves forced 
 farther apart, and after the cleansing are drawn together. This may 
 be done by using a strong iron wire. The wire should be heavier 
 than that used for taking the measurements of the roots, being 
 about twent}'-eight or thirty gauge in thickness and is placed 
 over the root and forced under the gum, down against the process 
 as far as possible. At times it may be necessary to slit the gum 
 on the labial side in order that it may be placed far up on the 
 root. The wire is twisted tightly on the labial side until the parts 
 are brought into close contact (Fig. 53). After the parts are 
 brought together, the excess of the twisted end of the wire is cut 
 away and the remainder pressed upward close to the gum so that 
 the sharp end may not injure the lip. 
 
 Frequently, a strong clamp placed over the root will assist very 
 materially in bringing the parts in close contact, and the wire is 
 pas.sed under this and tightened. The root is then very carefully 
 .shaped and a tightly fitting band made for it with pin and floor 
 comi)lete. The l)and should l)e made of heavier material tliaii for 
 an ordinary crown and twenty-eight gauge of coin gt)ld is here 
 indicated. 
 
 Tiie completed caj) is then j)ut in position, the impression taken 
 and the crown C()mj)leted. After the crown has been made, it 
 is cemented to th(! root aJid when the cement has thoroughly 
 hardened, the wire is remo\'ed. This renders the root perfectly 
 firm, and if the work lias been skillfully don<', it may last for a great 
 many years. 
 
 WIktc there is only a minor fractnrc of llic root, tiic |)i('c(' which 
 is broken away can be rcrno\c(l iind the bjind made to coxcr the 
 line of frarture. 
 
70 
 
 THE PULP CANALS 
 
 BANDING ROOTS WHICH HAVE BROKEN APART AND 
 SEPARATED. 
 
 Cases are met with where the roots of broken-down molar teeth 
 have separated from each other, but are still, individually, long 
 and firmly set. If properly treated, many of these may be used to 
 assist in supporting a bridge as well as though the entire tooth was 
 standing. 
 
 Take the case of an upper molar, where the palatal root has 
 become separated from the other two, as in Fig. 54. These roots 
 
 Fig. 54 
 
 Fig. 55 
 
 Fig. 56 
 
 should be brought together. The gum, however, must first be 
 crowded from between and from around the sides of the roots, so 
 that a clear impression of the outline can be obtained. 
 
 The canal in the palatal root and the canal of one of the buccal 
 roots are enlarged as much and as deeply as possible and pins 
 placed in them, and an impression taken. 
 
 A model is prepared from this and dried thoroughly. It is 
 then trimmed, carefully cutting down the sides of the root and 
 
 Fig. 58 
 
 Fig. 59 
 
 across- the line of fracture, care being exercised not to scrape the 
 sides of the roots in the least. The plaster is then cut away from 
 between the roots (Fig. 55), and the two parts are brought in con- 
 tact in their normal position and held there by waxing or setting 
 in fresh plaster (Fig. 56). A band is fitted to this plaster stump, 
 carrying it well into the depression where the roots are constricted 
 (Figs. 54 and 57). 
 
BANDING ROOTS WHICH HAVE BROKEN APART 71 
 
 The pins having been removed from the model, a staple of heavy 
 round platinized gold, or clasp wire, with a large loop (Fig. 5S), is 
 then made and fitted in the canals, as shown in the model, so as to 
 go in with a spring and hold the parts tightly together, as in Fig. 59. 
 This staple is then pressed still closer together and is forced in the 
 root in the mouth. The spring exerts a steady pressure and it 
 will generally be found that in a few hours the parts have been 
 brought into contact. The staple should be left in position for a 
 couple of days after the j)arts are in contact so that the roots may 
 become somewhat set in their proper position. The staple is then 
 removed, the canals thoroughly' cleansed ancl the staple reset with 
 cement. The band is then placed on the stump, the impression 
 and articulation taken and the crown finished in the usual manner. 
 After it has been cemented, providing the work has been carefully 
 done, the tooth will be practically as good as ever and will last 
 for manv vears. 
 
 Fig. 62 Fig. 63 
 
 Another case which is frequently encountered is where the two 
 roots of a lower molar have become separated, at times, for quite 
 a fHstance. If they are of good length and firmly set they can be 
 utilized. If they are standing far apart (Fig. (iO), it may be well 
 to crown the roots separately and then build up aii>' form of abut- 
 ment to carry a })ridge that conditions favor. If the distance is 
 not very great, say, not exceeding one-sixteenth of an inch at the 
 most, they can be treated in the same manner as iidvised for the 
 upper molar. If they are standing well out of the gum they can 
 frequently be brought more cpiickly together by ])laciiig a very 
 strong clamj) (Fig. OlJ over them, and leaving it for a time (Fig. 
 i')2). This will help to bring the separated roots together, and after 
 they are in contact they can be held in position with the staple in 
 the mamier already described (Fig. (VA). 
 
CHAPTER V. 
 
 RELATIVE STRENGTH OF THE TEETH AS SUPPORTS 
 FOR BRIDGE-WORK. 
 
 Those who do crown and bridge-work should have a good under- 
 standing as to the relative strength of the different teeth, and what 
 can be expected of them as supports in carrying a bridge. (The 
 carrying capacity of the different teeth varies greatly, and it is 
 important to know, approximately, what may be expected from 
 each.) 
 
 For many years the writer has made a careful study of this 
 subject with the view of determining just wdiat may or may not 
 be expected of the different teeth when serving as anchorages for 
 bridge-work. He has made many observations under widely varied 
 conditions, and has arranged a table for the upper and lower series. 
 
 Of course it is understood that conditions may exist which would 
 cause a variation in the order as given, but where the conditions 
 are normal the table will be found to be nearly correct. 
 
 Teeth in the Upper Jaw. — The teeth which may be considered 
 as first in strength and endurance as abutments are the cuspids. 
 These are followed by the first and second molars. It is perhaps 
 a question as to which of these teeth, the molars or the cuspids, 
 form the most permanent anchorages, but it is probable that the 
 balance is rather in favor of the cuspids. After the first and second 
 molars come the second and first bicuspids. It is really difficult to 
 choose between these teeth, as under proper conditions each seems 
 to do the work equally well, although, if there is any choice, it might 
 perhaps be given to the second bicuspid. 
 
 Next in order come the central incisors, then the laterals and 
 lastly the third molars or wisdom teeth. The third molars are 
 placed last in the list on account of the uncertainty regarding them, 
 and also their position being so far back in the mouth as to ren- 
 der them very difficult of access in devitalizing, treating, and in 
 preparing them for the reception of the crowns and fitting of the 
 bands. At times these teeth are large and strong and well rooted, 
 and will serve as abutments, practically, as well as the other molars. 
 
STRAIN ON A BRIDGE OCCLUDING WITH A PLATE 73 
 
 lasting for a great many years, but on account of the uncertainty 
 associated with them, they are placed at the end of the list. 
 
 Lower Series. — The strength of the lower series follows practically 
 the same order as those in the upper, with the exception that here 
 the lateral and central incisors are placed at the end of the list. 
 The roots of these teeth are very small and frail, and they are placed 
 last, notwithstanding the uncertainty associated with the third 
 molars. 
 
 Form of the Arch. — The formation of the arch is an important 
 factor in the carrying capacity of the teeth. A bridge which in 
 one mouth might be of the utmost value to the patient, in another, 
 where the conditions are seemingly the same, the teeth being 
 equally good, but with a differently shaped arch, bridge-work 
 might prove to be a detriment rather than a benefit. 
 
 Properly treated, a tooth can be made to do far more work than 
 it was originally intended to do. One tooth may do the work of 
 two or even three, under certain conditions, but these conditions 
 must be carefully and conscientiously studied. It is impossible 
 to lay down any fixed rules governing this point, and show just where 
 bridge-work is or is not indicated. In two cases, which on first 
 seeing may seem to be identical, there will be found some point of 
 dift'erence, such as occlusion, inclination of abutments, etc., w^hich 
 may necessitate the treating of one case in an entirely different 
 manner from the other. 
 
 Frequently, a case may be presented which at first glance seems 
 ideal for this kind of work, l)ut on studying it carefully, will prove 
 to be altogether unsuitable. On the other hand, a case, which on 
 first thought seems unsuitable, may, after careful scrutiny, prove 
 to be one of the best. To sum up in a few words, there are no two 
 cases which are exactly alike and each must be carefully studied 
 and decided upon its own merits. 
 
 THE STRAIN ON A BRIDGE OCCLUDING WITH A PLATE. 
 
 Whether a bridge is to occlude with natural teeth, or with arti- 
 fi(;ial teeth on a plate, may properly have a deciding infiuence when 
 coiisiflcring its construction. 
 
 If the bridge is to occlude with teeth on a i)lute it can be made 
 longer, and with weaker abutments, than would be safe were it to 
 <tcc\\u\(' witli natural teeth, as the force of mastication is far less 
 where a plate is worn than where the natural teeth are standing. 
 
74 RELATIVE STRENGTH OF THE TEETH 
 
 BRIDGE SUPPORTS. 
 
 When and Where Bridge-work is Indicated. — Although it is im- 
 possible to lay down any fixed rules governing this work, there are 
 some typical cases which are frequently presented that will be 
 considered. 
 
 Beginning with the simpler cases, take the anterior part of 
 the mouth where one tooth is missing, for example an upper 
 lateral, both of the adjoining teeth being in perfect condition. 
 Now, in the majority of these cases, a small plate is used to restore 
 the missing tooth, but the ideal fixture would be a small bridge 
 anchored to the adjoining teeth. 
 
 In a bridge of this kind, it is necessary that the tooth serving as 
 an abutment should be devitalized, and that tooth should always 
 be the cuspid. The reason for this is not that the central is a weak 
 tooth, for it would be amply strong to carry the dummy, but for 
 very good reasons which will be given later. 
 
 It is rarely that it is necessary or advisable to cut oft' the crown 
 of this abutment tooth, but by devitalizing it and using an inlay 
 abutment, we preserve the natural crown and the bridge will, if the 
 work be carefully done, last a long time. 
 
 There is an inflexible rule which should be followed in all cases of 
 restoration with bridge-work whether it be of a single tooth or of a 
 longer series of teeth. It is this, always have at least two swirporis jur 
 a bridge. Never trust to a single tooth to carry the dummy. Always 
 provide some additional support at the opposite end of the bridge, 
 if it has but a single retaining abutment, even though it be a slight 
 one. 
 
 When the two lateral incisors are missing, ordinarily the two 
 centrals will safely carry the dummies restoring the lost teeth, but 
 if the teeth should seem weak or the arch V-shaped, additional 
 support should be had in the way of a light spur resting against a 
 small gold filling or inlay on the lingual surface of the cuspids. 
 This will prevent the bridge from being forced labially. 
 
 Where the central incisors have been lost, the laterals will serve 
 as abutments. It is best to cut them off and crown them, as these 
 teeth are generally too weak and slight for inlay abutments, but they 
 should receive additional support from the cuspids, as in the case 
 of the missing laterals. 
 
 Where a central and a lateral, both of the same side, have been 
 lost, as in Fig. 64, the central and lateral of the opposite side may 
 
BRIDGE SUPPORTS 
 
 75 
 
 serve as the main or retaining abntments, but they should have 
 additional support from the cuspid in the way of a spur resting in 
 a pit or groove in a gold filling or an inlay. In a case of this kind, 
 the cuspid alone might serve as a retaining abutment with the spur 
 resting on the lingual side of the remaining central. 
 
 Where the central and lateral of opposite sides (Fig. 65) are to 
 be restored, the remaining central and lateral may be used with 
 additional support from the cuspids, as above. In either of the 
 above cases, if the lateral and central abutments are not very strong, 
 
 Fig. 64 
 
 Fig. 65 
 
 one or at times both of the cus])ids should be devitalized and 
 utilized as retaining abutments, using inlays and pins, or if the 
 bridge be removable inlays with tubes and split pins. 
 
 Where all of the incisors are missing, a lasting bridge may be 
 made by using only the cuspids as abutments, providing these teeth 
 stand well apart and the bridge can be made on nearly a straight 
 line with the abutments, or with only a slight outward curve, 
 (Fig. ()()). Where the arch is V-shaped and narrow, so that when 
 in position the center of the bridge will extend outward far 
 
 Fig. 66 
 
 Fig. 67 
 
 beyond the line of abutments, as in Fig. 07, the leverage would 
 be so great, if the cnspids only were used, as to force the body of 
 the bridge ui)vvard and outward, thus carrying the cuspid roots 
 forward, making a gradually incrcasiiig sj)a('e between the upjxT 
 and lower incisors and e\cntu;illy loosening the cnspid abutnients 
 (Fig. (iSj. 
 
 With an ardi of this shape, it is necessary to sccnrc sonic addi- 
 tionaj supports. Tliis can be done by utilizing the first l)icusj)ids 
 and gJN'ing tliem a broad otclusal surface. This will eU'ectually 
 
76 
 
 RELATIVE STRENGTH OF THE TEETH 
 
 overcome the tendency of the body of the bridge to move upward. 
 In order to do this, it would be necessary to force the bicuspid 
 abutments downward, the cuspids, which are always deeply set, 
 serving as a fulcrum, and this would be impossible on account of 
 their occlusion with the lower teeth. 
 
 In the case of a full denture there should be at least four good 
 strong abutments. The two cuspids and a first or second molar 
 
 on each side of the arch would form 
 an ideal case for a minimum number 
 of anchorages. A bridge of this kind 
 should be made in one piece, thus 
 making one side assist in supporting 
 the other. 
 
 Large Bridges One Piece or Divided. 
 — If, with only the four abutments, 
 the bridge is made in two parts, 
 divided at the median line, the tendency will be for the two halves 
 to be forced outward buccally, thus separating the parts and leav- 
 ing an ever-widening space between the central incisors. If we 
 increase the number of abutments, having the two central roots 
 in position, then the bridge might be made in two sections divided 
 at the median line. In a case of this kind, however, all of the 
 abutments should be made parallel, as they would be if the bridge 
 was to be made in one piece, so that if the parts ever showed a 
 tendency to separate, they could be removed and connected by 
 soldering, with the certainty that they would go easily into their 
 proper position in the mouth after having been united. 
 
 Fig. 68 
 
 Fig. 69 
 
 It should be remembered that we cannot have too many supports, 
 and that every additional abutment adds just so much to the 
 chances of long life for the bridge. 
 
 Another typical case is where the first bicuspid and first molar 
 have been lost, as in Fig. 69. In this case, ordinarily the second 
 bicuspid and second molar would be sufficient as abutments, unless 
 the bicuspid had moved back toward the second molar, so as to 
 leave a much greater space than could be filled by a single bicuspid 
 
CONDITIONS FOR SUCCESS IN CROWN AND BRIDGE-WORK 77 
 
 dummy; in which event the cuspid should be used as an additional 
 supporting abutment as the increased leverage of the dummies 
 would be too great a strain on the bicuspid abutment, Fig. 70, 
 The same plan should be followed where the two bicuspids are 
 missing and the two molars are used as abutments. 
 
 Where a single bicuspid or a single molar is missing, as a rule 
 there need be but a single retaining abutment, but the other end 
 of the bridge should have a support in the way of a spur resting 
 in a filling or an inlay. 
 
 ^Ye might go on indefinitely giving instances where bridge-work 
 might be used, but these few typical cases will serve as a guide for 
 further operations of this character which may be encountered. 
 
 CONDITIONS MAKING FOR SUCCESS IN CROWN AND 
 BRIDGE-WORK. 
 
 The success of crowji and bridge-work depends entirely on the 
 preparation of the teeth and roots. By this preparation, it is not 
 meant simply the mechanical trimming for the reception of the 
 bands or caps, but it begins at the beginning, the devitalization 
 of the teeth and the cleansing and filling of the canals. If this 
 is not properly done, bridge-work can never be a success. 
 
 A loose or diseased tooth does not necessarily preclude the idea 
 of using it as an abutment for a bridge. There are many times 
 where such teeth, by proper treatment, may be brought to a per- 
 fectly firm and health\' condition, and a tooth or root should not 
 be sacrificed as long as there is the slightest chance of bringing it 
 to such a state, but we should not decide definitely to use it until 
 it is certain that a cure has been effected. 
 
CHAPTER VI. 
 
 TYPICAL SHAPES OF THE TEETH. MECHANICAL 
 
 PREPARATION OF THE TEETH AND ROOTS 
 
 FOR THE RECEPTION OF THE BANDS. 
 
 The surgical treatment of the teeth having been properly carried 
 out, the success of the work then depends upon the mechanical 
 preparation of the teeth and roots for the reception of the caps or 
 bands. In order to do this properly, it is necessary that the operator 
 should thoroughly understand and be familiar with the anatomy 
 of the teeth. A careful study should be made of the shapes of the 
 different teeth as they would appear if cut off about one-sixteenth 
 of an inch below the gum line. ■ ^ 
 
 It is an excellent plan for the beginner to take the different teeth 
 and cut them off to about one-sixteenth of an inch beneath the 
 gum line, or grind them until the contour is entirely removed to 
 about that point, so that the band can pass over the stump and 
 fit the root tightly. He should not confine his study to a single 
 tooth of a given character, but should observe many, and note any 
 variation from the typical shape. There is a typical shape to all of 
 the teeth, and it is rarely that this shape will vary, probably not in 
 1 per cent, of all the cases encountered. 
 
 All of the teeth or roots, if properly prepared, present something 
 of an oval or triangular shape, being broad on the buccal or labial 
 side and narrower on the lingual or palatal side. This must, of 
 necessity, be the case in order that they may be accommodated in 
 the arch. The appended chart. Fig. 71, well illustrates this and will 
 give an idea of their various shapes as they would appear when 
 observed frorii the occlusal or incisal ends of the stumps or roots. 
 
 The cross sections are made at the extreme overlapping edge 
 of the enamel or about one-sixteenth of an inch beneath the gum 
 line, the distance to which the band is supposed to be carried on the 
 root, 
 
 TEETH OF THE UPPER JAW. 
 
 In making a study of the teeth in the upper jaw, we find that the 
 cuspids are nearly true ovals, or egg-shaped, being broad on the 
 buccal and narrower on the lingual sides. 
 
TEETH OF THE UPPER JAW 
 
 79 
 
 The shape of the hiteral incisors is ahnost an exact reproduction 
 of the cuspids but of course being very much smaller. 
 
 Vui. 71 
 
 In the first bicnspid, while it still preserves the same general oval 
 shape, it will be seen that it is innch broader buccally and linf,nially 
 pntportionalely, than are the cuspids, the buccal and lin<;ual 
 diameter of llii.> tooth beiu'^ nearl\- twice as <ireat as the mesial 
 
80 TYPICAL SHAPES OF THE TEETH 
 
 and distal. After the contour has been entirely removed from this 
 tooth to about one-sixteenth of an inch below the gum line, it will 
 be found by following the curve of the buccal and lingual sides of 
 the root and completing the circle on each of these sides, that there 
 will be two perfect circles, the lingual being slightly smaller than 
 the other (Fig. 72). 
 
 The second bicuspid root is practically of the same shape as the 
 first, the only difference being that the second bicuspid root will be 
 slightly smaller than the first, but the proportionate mesial distal 
 and buccal and palatal diameters remain practically the same. 
 
 In the first molars, this tjiangular shape is still preserved, but as 
 in the case of the bicuspid, the buccal and lingual diameter is usually 
 
 Fig. 72 Fig. 73 
 
 about twice as great as the mesial and distal, being broader on the 
 buccal side, where we have the two buccal roots, and narrower on the 
 lingual, where there is but one. This may vary at times, and the 
 tooth be as broad, or even broader on the lingual side, when there 
 is an excessively large palatal root and the disto-buccal root sets 
 well inside of the arch between the mesio-buccal, and palatal root 
 as in Fig. 73, but this is an abnormality and very rarely occurs. It 
 will always be found that the distal root sets considerably farther 
 inside the arch than does the mesial, thus giving the stump a more 
 distorted appearance. 
 
 The second molar presents the same general shape as in the case 
 of the first, but the stump is proportionately a little shorter buccally 
 and lingually than is the first molar. 
 
 Very rarely the first or second molars have but a single root 
 and then again, at times, they may have four. In the latter case, 
 the palatal side will nearly always be broader than the buccal, as 
 the two palatal roots usually follow the curve of the arch more 
 nearly than do the buccal roots, and stand side by side mesially 
 and distally, one directly behind the other (Fig. 24). 
 
 With the third molar, or wisdom tooth, if it has the normal 
 
 number of roots, it will have the same general shape as in the other 
 
 two molars, but this will be still smaller proportionately, buccally 
 
 "and lingually, than the second, being more nearly round than are 
 
TE^TH OF THE LOWER JAW 81 
 
 the others. However, the shape of this tooth is subject to a greater 
 variation than are any of the others, as it may have but a single 
 root or at times even as many as five or six. 
 
 The central incisors, have still the same general ovoid form as the 
 others, but somewhat distorted. This root has more the general 
 outline of the molars, but is proportionately very much shorter 
 labially and lingually, and is decidedly triangular in shape. If these 
 teeth are properly set in the arch, there will be a V-shaped space 
 between the two roots lingually. The distal sides of the labial face 
 of these roots, as in case of the molars, set a little farther in the 
 inside of the arch than does the mesial. 
 
 TEETH OF THE LOWER JAW. 
 
 In the lower jaw we find the central incisors still preserving their 
 oval character, but decidedly different in shape from the upper, 
 being proportionately much longer labially and lingually than are 
 the centrals in the upper. These roots are very small and as a 
 general rule are of little value as supports in bridge-work. 
 
 The lateral incisors are practically of the same shape and char- 
 acter as are the centrals, but somewhat larger, and while not of 
 particular value as supports for a bridge, still they are much better 
 than are the centrals. The shape of both of these roots, is often 
 very much like that of the upper second bicuspids, and at times the 
 labiolingual diameter is nearly twice that of the mesial and distal. 
 
 The cuspids, as in the upper, are nearly true ovals, but the lingual 
 corner is generally much sharper than is the case with the upper 
 cuspids. 
 
 The first and second bicuspids are also nearly true ovals and l)()th 
 practically of the same shape, the first being slightly smaller than 
 the second, but the lingual side is proportionately broader and 
 rounder than are the cuspids. 
 
 The shape of the lower molars is very different from tiiat of the 
 molars in the upper jaw, but they still tend to the oval. 
 
 First Molars. — This tooth is more nearly square, l)eing 
 broad anrl nearly flat on the mesial side, the same on the 
 buccal and lingual, the lines converging slightly toward the 
 distal, while the distal side is more convex owing to the 
 difl'erence in the shapes of the roots (Fig. 74). The mesial root is 
 almost exactly the same in character and shape as the n|)per second 
 bicuspifl rf>ot, the; buccal and lingual diameter being about twice 
 6 
 
82 TYPICAL SHAPES OF THE TEETH 
 
 that of the mesial and distal, while the distal root is more rounded 
 than is the mesial. If there has been a recession of the tissues 
 there will be a slight depression on the mesial side of the stump 
 where the root is constricted, and also on the buccal and lingual 
 sides where the roots begin to bifurcate (Fig. 74). 
 
 The second molar presents the same general shape, but the distal 
 root is smaller, making this tooth slightly narrower proportionately 
 on the distal side than is the first molar. 
 
 With the third molar, if they have the normal number of roots, 
 the distal root is still smaller, the prepared stump often forming an 
 almost perfect triangle, with the corners rounded. As is the case 
 with the upper wisdom tooth, however, the shape of this tooth 
 is subject to more variation than are the others, as they may have 
 but a single root or they may have several. 
 
 The foregoing is a fairly accurate description of the shapes which 
 the stumps of the different teeth will present after they have been 
 properly prepared for the reception of bands. If we carry these 
 shapes in mind, we will find that the work of trimming will be very 
 much simplified. In trimming, we are always working toward the 
 typical shape and being familiar with these shapes will materially 
 aid us in the work of preparation and will also enable us more readily 
 to detect any variation from the typical formation. 
 
 TRIMMING OF THE TEETH. 
 
 Wherever bridge-work is used, it is necessary that the teeth 
 or roots, which are to serve as abutments, should be reinforced as 
 much as possible in order to give strength and stability to the 
 abutments, and also to overcome, as far as may be, the possibility 
 
 of their being fractured. In order to accomplish this result, it is 
 essential that the roots should be banded. To do this properly, 
 the contour of the tooth must be entirely removed, so that the band, 
 when it is passed over the crown of the tooth, will hug the neck 
 tightly, and reduce the possibility of gingival irritation to a minimum 
 
TRIMMING OF THE TEETH 83 
 
 (Fig. 75). If this contour is not removed, the band will stand away 
 from the root, cut into the tissues and set up an irritation which may 
 eventually result in the loss of the tooth (Fig. 76). 
 
 In all of the teeth the bulk of the trimming will be on the mesial 
 and distal surfaces, the contour of the crown being greatest at the 
 points of contact with the adjoining teeth, and gradually diminishing 
 as we approach to gum line, until at a point about one-sixteenth 
 of an inch beneath this line, or at the overlapping junction of the 
 enamel with the dentin, it entirely disappears. 
 
 Trimming of Lower Molars. — In taking up the technic of the 
 preparation of the teeth for the reception of the bands, the prepara- 
 tion of the lower first or second molar will be first consitlered. 
 
 Mewed from the buccal or lingual sides, the contour of these teeth 
 is very great. The mesial and distal diameter at the point of contact 
 with the adjoining teeth is from one-third greater to, at times, even 
 twice that which it is at the neck, or about one-sixteenth of an inch 
 
 i-iG. 76 
 
 below the gum line, at the point of junction of the enamel with 
 the dentin. Viewing them from the occlusal surface, they are 
 oblong, generally being slightly broader at the mesial side than at 
 the distal side. 
 
 The teeth should be trimmed so that the sides are very nearly 
 parallel, being slightly larger at a point about one-sixteenth of an 
 inch beneath the gum line (Fig. 77). It is very necessary that the 
 stumps should not be made too conical, as if this is done, there will 
 be very little hold for the crown which is to be placed on it and after 
 being cemented it would require but a slight blow or strain to loosen 
 it (F'ig. 78). On the other hand, if the sides are nearly parallel, 
 a very strong retention is obtained and it would require a greater 
 strain than is orrlinarily brought to bear on the teeth to loosen the 
 cap from its position (Fig. 79). 
 
 In order to give the teeth the desired shape, it is necessary to 
 have instruments of suitable design, so that the work of preparation 
 may be performed easily, and at the same time with as little pain 
 and inconvenience to the patient as possible. 
 
84 
 
 TYPICAL SHAPES OF THE TEETH 
 
 The trimming of these teeth cannot be done with a hand-instru- 
 ment, as the bulk of material which must be removed, in order to 
 allow the passing of the band, is so great that if sufficient force were 
 exerted to strip the enamel or contour from the tooth, it would be 
 great enough to remove the tooth from the socket, so that the 
 only way to remove it is by grinding. 
 
 It is impossible to prepare these teeth with a straight flat-faced 
 wheel, so that they will be parallel with an anterior abutment, as 
 in order to remove the contour entirely on the mesial side, it is 
 would be necessary to cut far back toward the center of the tooth, 
 
 Fig 
 
 thus giving it a backward slope from the gum line (Fig. 80) . Further- 
 more, to remove the contour from the distal side with a straight, 
 flat-faced wheel would necessitate cutting forward and into the distal 
 root, leaving a ledge which would render the fitting of the band 
 
 Fig. 81 
 
 extremely difiicult (Fig. 81). This trimming is best done with a 
 saucer-shaped disk, as shown in the iflustration (Fig. 82). With 
 this the sides can be reached from almost any angle, the contour 
 
TRIMMING OF THE TEETH 
 
 85 
 
 easily removed, and at the same time the parallelism with the 
 anterior abutment preserved. 
 
 The wheels which have been found most suitable in these cases 
 are the Leaming disks, or wheels of the same design. These Learn- 
 ing disks are made of carborundum and vulcanite, are very uniform 
 in textiu-e and are much superior to the ordinary carborundum 
 wheels, as they will wear evenly and remain perfectly round and true 
 until thev are worn awav entirelv to the hubs. 
 
 Fig. 82 
 
 The disk, which is used most frequently, is known as No. 421, 
 (Fig. 82). This disk is very thin and of an equal thickness from 
 center to circumference. This disk is suitable only for cutting 
 on its edge as it is very thin and continued pressure on either the 
 face or reverse side is liable to break it off at tlie hub. 
 
 Fig. H3. — liiilb syriiiKP. 
 
 The wheel and tooth should be kept constantly flooded with cold 
 water, preferal>ly iced. This can best be done with a .syringe small 
 enough to be held in the left hand, at the same time leaving some 
 of the fingers free to hold the lijjs or cheek out of the way of the wheel. 
 A small bulb syrinue is most siiitablc for tliis piirpos(i (r'ig. H^). 
 
TYPICAL SHAPES OF THE TEETH 
 
 There are appliances made for keeping the wheels wet which are 
 attached to the hand-piece, the water being carried through a 
 tube to the wheel (Fig. 84), but generally these are not as satis- 
 factory as the ordinary syringe; as they are in the way of the operator 
 and do not allow of a firm grasp on the hand-piece. When an assist- 
 ant is employed at the chair, the operator can hold the lip or cheeks 
 away with a mirror or other suitable instrument, while the assistant 
 drops the water. 
 
 Devised by Dr. C. E. Edwards. 
 
 The tooth is examined carefully with an explorer in order to 
 determine the approximate amount of tooth structure which will 
 have to be removed. The edge of the wheel is then placed on the 
 occlusal surface at just about the point determined by the explorer, 
 and the bulk of the contour can be removed in one piece (Fig. 82). 
 
 The hand-piece should be firmly held so that it is impossible for 
 it to escape from the control of the operator. It is grasped between 
 the thumb, and the first and second finger of the right hand. In 
 working in the lower part of the mouth, the third and fourth fingers 
 are braced firmly against the anterior teeth in the lower jaw, as in 
 Figs. 85 and 86. In this manner the instrument is held perfectly 
 steady, and should it become jammed between the teeth, the wheel 
 might be broken, but could hardly escape from the operator's 
 control so as to injure the tongue or cheek of the patient. 
 
 By working in this manner, the operator has absolute control 
 of the instrument and the firm grasp will inspire his patient with 
 
TRIMMING OF THE TEETH 
 
 87 
 
 confidence in his abilit\- to do the work with the least possible 
 injury to the soft tissues. 
 
 If the dentist be left-handed, the method of work just described 
 should be reversed. 
 
 Trimming the Lower Molars. — Mesial Side. — In trimming the 
 lower molars, there are three principal cuts to be made (see Fig. 87). 
 The first, and generally the greatest, is on the mesial side of the 
 tooth. The second is on the distal side while the third is on the 
 lingual side. These cuts should be made in the order here given. 
 
 Fig. 8.5. — Shows the position of the hands and instruments in trimming the 
 teeth in the lower left side of the mouth, while Fig. 86 shows the position in working 
 on the right side. 
 
 The explorer shown in the illustration (Figs. S8 and 89), is most 
 suitable for use while trimming the teeth, as it is so shaped that 
 every part of a tooth is easily accessible to it and the sides of a very 
 long tooth can be reached to, or even beyond, the gingival border. 
 
 Mesial Side. — In grinding, the hand should be held very steady and 
 tli<- wliccl must not be forced, but should be allowed to work its way 
 through the tooth with little more pressure exerted than that which 
 
88 TYPICAL SHAPES OF THE TEETH 
 
 the weight of the hand-piece gives to. it. This is continued until 
 the contour on the mesial side of the tooth has been removed (Fig. 
 90). If on examination with the explorer, it is found that not quite 
 enough of the tooth structure has been taken away, and that there 
 still remains a little shoulder, as shown in the illustration (Fig. 91), 
 the use of another wheel is indicated. This wheel is known as No. 
 
 422 (see Fig. 91) and is of the same make as No. 421. It is saucer- 
 shaped, as is the other, but as seen by the illustration, that while it 
 comes down to a fairly sharp edge, it thickens gradually as it 
 approaches the hub, and is made of a coarser material. It is much 
 stronger and cuts more rapidly than does the No. 421. The wheel 
 being thick and strong, the face or reverse side of it can be used. 
 
TRIMMING OF THE TEETH 
 
 89 
 
 The shoulder left after using the fine wheel should be examined in 
 order to determine just about how much more material it is necesary 
 to take away. The face of this wheel is then placed against the tooth, 
 the same angle being preserved as with the first wheel, and the face 
 of the tooth cut back until the explorer shows that we have gone 
 the required distance (Fig. 92). 
 
 Fig. 90 
 
 Fig. S7 
 
 Fio. 88 
 
 Fig. 91 
 
 FiQ. 89 
 
 This will leave a little ledge, because this wheel should not be used 
 for cutting below the gum line, as its thicker edge and coarser 
 material would mutilate the gum unnecessarily. 
 
 The thin disk, No. 421 with which the first cut was made is then 
 used, placing the edge of the wheel on the ledge and cutting to the 
 
00 TYPICAL SHAPES OF THE TEETH 
 
 required depth beneath the gum Hue. The explorer is now used and 
 sh'ould pass freely under the gum, and smoothly along the root. If 
 it is found that it is the least bit too full, the cutting should be con- 
 tinued until it is perfectly flush and smooth with the side of the root. 
 
 It should be understood that to trim the teeth properly it is 
 necessary to mutilate the gum tissue more or less. If the contour 
 is entirely removed it is necessary to cut to a sufficient depth 
 beneath the gum line and the loss of a little blood should occasion 
 no alarm. There is no tissue in the body which heals as quickly 
 as the gum tissue. In a perfectly healthy mouth, even where the 
 gum has been quite badly mutilated, the tissue will be found 
 entirely healed in a few days. It is absolutely essential in all of 
 these operations that the instruments be perfectly sterile. 
 
 By using ice-water freely, in fact to have pieces of ice in the glass 
 from which the water is taken it will act as a partial local anesthetic 
 for the time being, so that the cutting beneath the gum can be accom- 
 plished with much less pain to the patient than it would be otherwise. 
 
 Distal Side. — The mesial side having been satisfactorily finished, 
 the second principal cut in the trimming should be undertaken 
 (Fig. 87). This cut is made with the same wheel or disk as was 
 used in trimming the mesial side. 
 
 It should be remembered that the distal roots of these teeth are 
 more rounded than the mesial. If the hand-piece be held perfectly 
 steady in grinding down this side, owing to the shape of the wheel 
 the distal surface of the stump would be ground concave rather than 
 convex. This can be overcome by giving the hand-piece a to and 
 fro sidewise motion following the outline of the root, determining 
 with the explorer whether it has been done accurately. This should 
 be carefully watched, and the grinding continued, using the same 
 motion, until the instrument shows that the contour on this side 
 of the tooth has been entirely removed. 
 
 Trimming of the Lingual Side.- — ^The natural inclination of these 
 teeth is lingually, as will be seen in the illustration (Fig. 93), and 
 in making this third cut they should be ground so that the lingual 
 side is nearly perpendicular. 
 
 In removing the lingual contour, it is best to stand on the side 
 of the patient on which the tooth to be trimmed is located. If the 
 tooth is standing by itself, a thin fiat disk (Fig. 93) may be used, 
 and nearly the whole amount of the contour removed with one cut, 
 starting from the occlusal surface in the manner already described 
 in the trimming of the mesial side (Fig. 93). The trimming of this 
 
TRIMMING OF THE TEETH 
 
 91 
 
 side should be carried well below the gum line, perhaps even further 
 than on the mesial or distal sides. 
 
 A smaller wheel of a different shape may also be used for this 
 purpose, and also to complete the trimming, after the bulk of the 
 contour has been removed. This wheel, one of the Leaming set, 
 is of an inverted cone-shape and known as Xo. 500 (Fig. 94). 
 
 Fig. 94 
 
 If there is an adjoining tooth, great care must be exercised so 
 as not to mutilate it, and in that case, we would use the reverse 
 side of the Xo. 500 throughout the trimming of this surface (Fig. 94). 
 
 Fig. 95 
 
 Fig. 96 
 
 There are diamond disks made to correspond in shape with these 
 wheels, which work beautifully. The disk Xo. 1 , Fig. 95, corre- 
 sponding in shape to the Xo. 500, can be used wherever the Xo. 
 oTK) is iridicatefi. 
 
 The disk Xo. 2, Fig. 9b, of the shape of the No. 421, will take the 
 
92 TYPICAL SHAPES OF THE TEETH 
 
 place of the carborundum disk of that number and also of the No. 
 422, as it is made of copper charged with diamond dust, there is 
 no danger of the disk being broken when using it on its face or on 
 the reverse side. 
 
 The initial cost of the diamond disks is much greater than that of 
 the carborundum and vulcanite, but as they will last a great deal 
 longer they are perhaps the cheapest to use in the long run, as 
 one of them will probably outwear a dozen or more of the others 
 and will not break should it become jammed. 
 
 Buccal Side. — ^The three sides of the tooth having now been 
 completed, there remains the buccal side to be trimmed. 
 
 As will be seen from the illustration (Figs. 93 and 94) when the 
 lingual contour has been removed so that this side of the tooth is 
 nearly perpendicular, there is very little tooth structure to be re- 
 moved from the buccal side and at times, if the lingual inclination 
 of the tooth is excessive, there may be nothing at all. The little that 
 may have to be removed can be taken away with the reverse side 
 of the inverted cone. No. 500. It is most easily reached from the 
 opposite side of the mouth, grinding away a little at a time, using 
 great care not to cut too much, as should this happen it will leave a 
 shoulder or ledge under the gum over which the band must pass, 
 thus making the fitting of the band a very difficult operation. It 
 will be found necessary to remove a little more structure toward 
 the distobuccal side, as the buccolingual diameter of the distal 
 root is somewhat less than that of the mesial. 
 
 Fig. 97 
 
 At times, where the mouth is large or the cheeks are very flexible 
 and can be drawn well back, the trimming of this side of the tooth 
 can be done with the flat face of the No. 500 wheel (Fig. 97), or 
 the face of a small flat disk, working from the side of the mouth 
 
TRIMMING OF THE TEETH 93 
 
 on which the tooth is located (Fig. 98), using, of course, extreme 
 care to protect the adjoining teeth. 
 
 The trimming of the four sides of the tooth having been satis- 
 factorily completed, it will be found that the stump is nearly square, 
 being slightly narrower on the distal side than on the mesial and it 
 should also be slightly conical, being a little larger just below the gum 
 line. The operation is completed with the rounding of the corners. 
 
 Fig. 98 
 
 The mesio-lingual corner can be reached by using the No. 421 
 disk or the diamond disk corresponding to that number, working 
 from the opposite side of the mouth and giving a rotary or swinging 
 motion to the hand-piece, being careful not to cut too deeply into 
 the stump so as to leave a ledge. 
 
 The mesio-buccal corner can be reached with the same wheel 
 or with the face of a small flat disk, using the rotary motion and 
 carefully following the curve of the root at that point. 
 
 In trimming the distal corners, if the tooth is standing alone, 
 they can be easily rounded by using the reverse side of the No. 500 
 wheel and giving jt a rotary motion sweeping around the corners 
 from side to side. If there is a tooth adjoining the one which is 
 being trimmed, it will be necessary to use more care in grinding. 
 A part of this corner contour can be removed by using the reverse 
 side of the inverted cone, going as nearly to the gum line as possible 
 without cutting the adjoining tooth. After the operator has taken 
 away all that he can with the disk, it will be necessary to remove 
 aii\- corners or points remaining with scalers, or other suitable 
 hand-instrument. 
 
 The rjiamond disk corresponding to No. 500 can be mounted 
 on a suitable mandrel with the face or concave side of the disk 
 outward, and if used in the right-angle hand-piece, the distal cor- 
 ners can be finished to a sufncicnt depth beneath the gum line, so 
 that there will be no necessity for using the hand-instrument. 
 
94 
 
 TYPICAL SHAPES OF THE TEETH 
 
 Very coarse emery cloth disks will be found to be a great help 
 in rounding and finishing the distal corners of these teeth, after 
 they have been rovighed down with the carborundum or diamond 
 disks. These are also especially useful where there is an adjoining 
 tooth standing distally to the one which is being prepared. Their 
 flexibility renders it possible to follow the rounded corners of the 
 roots and at the same time, as they are safe-sided, there is no 
 possibility of injuring the face of the tooth behind it. 
 
 Where there is a very great forward inclination of the molar, 
 as is so frequently the case, where teeth anterior to it have been 
 lost for some time, as in Fig. 99, there will be little or no cutting 
 
 Fig. 99 
 
 necessary on the distal side of the tooth. All of the trimming, 
 will be on the mesial side. The tilting of the tooth so far forward 
 will allow of the band being passed perpendicularly over the crown 
 of the tooth, clearing the enamel on the distal surface and striking 
 the neck of the tooth beneath the gum line, as in Fig. 99. 
 
 The same wheel should be used for grinding the mesial surface 
 of the tilted tooth, as would be used were the tooth to stand in 
 normal position. In such cases it is necessary to start far back to 
 or beyond the center of the tooth and cut well below the gum line 
 on the mesial side, even farther than it would be, were the tooth 
 standing upright so that if the band were the fraction of an inch 
 longer than necessary it would not pass beyond the trimmed side 
 of the root and leave a sharp edge cutting into the tissues, as the 
 
TRIMMING OF THE TEETH 
 
 95 
 
 inclination of the root is such that there would be a very decided 
 overhangino; ledge at any depth on the root to which we might 
 grind (see Fig. 99). 
 
 Fig. 100. — Show.s the position of the small cup-shaped disk in trimming the distal 
 side of the lower bicuspids or molars. 
 
 The buccal and lingual surfaces of the tooth are trimmed in the 
 manner already described, using the same instruments as where 
 the tooth stands in normal position. 
 
 It should be remembered that it is better to oxer- 
 trim a tooth than to undertrim it. If too much of 
 the contour is removed, so as to leave a ledge beneath 
 the gum, so that the band cannot pass over it, the 
 band can rest on this Icflge and do very little harm 
 (Fig. 101); whereas, if undertrimmed, the band will 
 stand away from the neck of the tooth below the 
 gingival margin and with the ragged line of cement may set up 
 an irritation which will c\entuallv result in the loss of the tooth. 
 
 Fid. 101 
 
96 
 
 TYPICAL SHAPES OF THE TEETH 
 
 Lower Bicuspids. — In trimming the bicuspids, the same methods 
 and wheels may be used as in trimming the molars, using the edge, 
 face and reverse side of the wheels. The mesial and distal contour 
 of these teeth may often be removed in one piece, as in the case of 
 the molars; but it frequently happens that the contour is not 
 sufficient to allow of this. In such cases the operator should cut 
 down between the teeth carefulh' and remove the contour verv 
 
 Fig. 102. — Shows the manner of using the small cup-shaped diamond disk in the 
 right angle hand-piece in trimming the buccal side of the bicuspids and molars. 
 
 gradually, using the Xo. 421 disk. The No. 500 can be used for 
 the lingual and buccal sides. The greater amount of contour 
 here, as in the case of the molars, is on the lingual side, but 
 proportionately not so great as in the case of the molars. 
 
 The mesio-lingual corners of the lower bicuspids are the most 
 difficult to reach, and in many instances it may be necessarj^ to 
 use a scaler to remove the tooth-structure at these points which 
 has been left by the wheel. However, the diamond disk corre- 
 sponding to the No. 500 used in the right angle, will very materially 
 assist in the operation, held in the same manner as in Fig. 102. 
 
TRIMMING OF THE TEETH 
 
 97 
 
 The mesio-buccal comers can be best rounded by using the face 
 of ven thin, small flat disks, and giving the hand-piece a rotary 
 motion. The trimming of the distal comers should be done the 
 same as in the molars, using the reverse side of the X(j. .'>(X) wheel 
 and rotating to follow the cur\'e of the rrxjt. In case there is an 
 adjoining t(x>th, the scalers or the inverted cone diamond disk 
 may be used in the right angle. 
 
 Flo. lO'J. — .Shows the same instruincnt in the right angle trimniiug the lingual tade 
 of the lower hicur/sidi;. 
 
 The Upper Molars. — The shape of the upjx-r molars is very 
 different from that of the lower molars, although as in the case 
 of the lower molars, the greatest amount of t(xjth stmcture to be 
 removed is from the mesial and distal surfaces. 
 
 The cTowns of the upper molars, viewed from the occlu.sal surface, 
 are diamond-sha[)efl, the greatest diameter Ix-ing from the anterior 
 buccal comer to the j>osterior palatal (Fig. JfM;. The same wheels 
 may be u.sed in their preparation as were used in the preparation 
 of the lower molars. 
 
 7 
 
98 
 
 TYPICAL SHAPES OF THE TEETH 
 
 As in trimming the lower molars, there are three principal cuts 
 to be made, mesial, distal and buccal (Fig. 105). 
 
 A.B. 
 
 Fig. 104 
 
 Fig. 105 
 
 Mesial Side. — The first cut is on the mesial side of the tooth, 
 and the bulk of the contour will be found at this point, being slightly 
 greater than that on the distal side. The first cut should be made 
 
 Fig. 106 
 
 with the No. 421 carborundum or with the diamond disk of the same 
 shape. The bulk of the contour can be removed with a single cut. 
 In trimming the right upper molars, the third and fourth fingers 
 are braced on the lower anterior teeth in the manner shown in the 
 illustration (Fig. 106). 
 
TRIMMING OF THE TEETH 
 
 99 
 
 In grinding the left npper molars, the third and fourth fingers 
 are braced on the lingual surfaces of the upper anterior teeth (see 
 Fig. 107). 
 
 If an examination shows that a sufficient amount has not been 
 removed, wheels of the same character can be used as on the 
 lower molars, cutting back for a distance at the gum line with 
 the Xo. 422 or diamond disk, and finishing with the No. 421. 
 
 Fk;. 107 
 
 Distal Side.— The distal side of the ui)i)er molars, unlike that 
 of the lower molars, is nearly flat. The contour on this surface 
 can be removed with the No. 421, or the diamond disk, rotating 
 the hand-piece slightly from side to side, but not so much as in the 
 case of the lower molars. 
 
 If the tooth has extruded or the gum has receded around the 
 neck, it will generally be found neces.sary to groove this surface 
 slightly miflway between the buccal and palatal sides, in order 
 to allow the band to be bent in at this place, so that it will hug the 
 root at the f)oint where the roots begin to bifurcaU'. 
 
100 
 
 TYPICAL SHAPES OF THE TEETH 
 
 ' Disto-buccal Side. — The third principal cut will be on the disto- 
 buccal corner. The distal root, setting further inside the arch 
 than the mesial, the contour is consequently greater at that point. 
 The removal of the contour from the distobuccal side may be 
 accomplished with the No. 500 or diamond disk, using the reverse 
 
 Fig. 108.- 
 
 -Shows the manner of using the small diamond disk in the right angle 
 hand-piece in making this cut. 
 
 side and working from the opposite side of the mouth, giving a slight 
 rotary motion to the hand-piece, or with the diamond disk used 
 in the right angle hand-piece, care being used not to cut too deeply 
 (Fig. 108). _ . _ 
 
 Mesio-huccal Side. — On the mesio-buccal corner it will be found 
 that there is very little, and at times nothing at all to be removed, 
 as frequently there is practically no contour at this point, the root 
 
TRIMMING OF THE TEETH 101 
 
 at the gingiva being nearly flush with the crown of the tooth. This 
 
 necessitates only the rounding oft' of the sharp corner, which can be 
 
 done with the face of a thin flat disk, rotating from side to side, using 
 
 care not to cut into the root so as to leave a ledge, as a ledge at this 
 
 point would render the fitting of the band much more difficult. 
 
 Palatal Side. — On the palatal side it will also be found that there 
 
 is very little contour (Fig. 109) and that it can be removed with 
 
 the reverse side of the No. 500 wheel or diamond 
 
 disk, working from the side of the mouth on which 
 
 the tooth is located, and rotating to follow the curve 
 
 of the palatal root 
 
 The corners mav be rounded with the wheels of the 
 
 1 " 111 1 • ^^^- 1*^9 
 
 same character as were used on the lower molars, usmg 
 
 the No. 421 or diamond disk for the mesio-palatal, with the rotary 
 
 motion, and the reverse side of the No. 500 for the distal corners. 
 
 The emery cloth disk will also be found useful in rounding and 
 
 smoothing the distal surfaces and corners. 
 
 Upper Bicuspids. — The bicuspids of the upper jaw, wherever a 
 shell crown is indicated, which is rarely, are prepared in the same 
 manner as are those of the lower, the same character of wheels, 
 being used. The corners of the upper bicuspids are much easier 
 to get at and trim than are those of the lower jaw, and the bulk 
 of the tooth structure left at these points by the wheel can 
 generally be easily removed with a hand instrument. 
 
 In cutting oft the occlusal surface, enough of the tooth structure 
 should be removed to allow of the placing of a thick solid cusp. 
 Usually there should be not less than one-sixteenth of an inch 
 between the top of the stump and the occluding teeth. This can 
 readily be ground away with a square-edged carborundum or corun- 
 dum wheel. The corners at the occlusal surface should be rounded 
 slightly and smoothed so as to prevent their cutting the tongue or 
 cheek. 
 
 If, for any reason, after the teeth have been prepared and ready 
 for the impression, the bridge cannot be placed in the mouth for 
 some weeks, as would be the case if the patient were leaving the 
 city for a time, it would be better to leave the occlusal surfaces 
 of the teeth intact. The bands are placed in position, and the 
 impression taken. 
 
 The models are then prej)ared and after the bands have been 
 removed, the occlusal surfaces of the abutment stumps on the 
 models are cut away to a sufficient depth. 
 
102 
 
 TYPICAL SHAPES OF THE TEETH 
 
 The bridge is then completed, and when the patient returns, 
 before undertaking to place the bridge in the mouth, the occlusal 
 surfaces of the stumps are ground away to a depth corresponding 
 to that which has been removed from the model. 
 
 It very frequently happens, where the teeth have been trimmed 
 and the occlusal surfaces ground away, that the irritation neces- 
 sarily attending their shaping will cause these stumps to elongate 
 very rapidly, or shift their position, so that if several weeks have 
 elapsed between the taking of the impression and the placing of the 
 bridge they may have extruded so far as to be in contact with the 
 occluding teeth. This would necessitate the further grinding of 
 the occlusal surfaces, with the result that, from the necessity of 
 the band passing so much farther on the stump than it did originally, 
 the fit at the gingival end might be impaired or entirely destroyed. 
 
 By leaving the cusps intact, however, the danger of the teeth 
 elongating is entirely overcome, and at the same time, the cusps 
 interlocking with their antagonists, the teeth are held in their 
 original position and prevented from shifting, 
 
 Trimming the Anterior Teeth. — In the preparation of the ante- 
 rior teeth the work should be done almost entirely with hand 
 instruments. 
 
 Fig. 110 
 
 Fig. Ill 
 
 Fig. 112 
 
 Fig. H: 
 
 When trimming these teeth, the stump should be left standing 
 out of the gum for from one thirty-second to one-sixteenth of an 
 inch, until after the contour has been entirely removed, and the 
 band has been fitted (Fig. 110). The reason for this is as follows: 
 
 If the root be cut at once below the gum line, as it will be even- 
 tually, in order to hide the band when the crown has been completed 
 and put in place, the gum will crowd over the face of the root 
 (Fig. HI). This, and the excessive bleeding which is sure to 
 occur, will interfere with the vision and render the operation of 
 trimming much more difficult for the operator and decidedly more 
 
TRIMMING OF THE TEETH 
 
 103 
 
 painful for the patient. The taking of the measurement of the 
 root is rendered much more difficult and at times practically 
 impossible, especially if there has been a great deal of recession 
 of the gum on the labial side. 
 
 The difficulty of fitting the band is greatly increased, as each time 
 the band is placed over the stump, it is necessary to crowd the gum 
 
 Fig, 114 
 
 Fig. 115. — Enamel scaler. 
 
 away in order to place it, so that on the whole it is \ery disagreeable 
 and in (satisfactory to both patient and operator. 
 
 Where the stump is left extending out of the gum, it serves as a 
 guide for the instrument in trimming and enables the operator 
 to .see much more clearly just what he is doing. It also serves as a 
 guide in taking the measurement and in fitting the band by keep- 
 ing the gum away, and enabling the fitting to be done better and 
 inudi more quickly, and with far less pain to the patient. 
 
104 
 
 TYPICAL SHAPES OF THE TEETH 
 
 After the band has been fitted, it may be removed and the stump 
 cut to any desired depth below the gum hne, after which the band 
 can be replaced on the root and scribed around on the inside at 
 the top of the stump, so that it may be trimmed to the proper 
 length. 
 
 The maximum diameter of the root is at the point of junction 
 of the enamel with the root, and this diameter generally continues 
 
 Fig. 116.- 
 
 -Shows the trimming of the lingual, mesial, and distal sides of the right 
 cuspid root. 
 
 about the same for from one-sixteenth to one-eighth of an inch 
 below the enamel before the root begins to taper (Fig. 1 12). 
 
 If this enamel is entirely removed, it will be found that the root 
 is of about the proper shape for the reception of the band so that 
 it will hug the root tightly (Fig. 113) unless there has been an 
 excessive recession of the gum, in which case it would be necessary 
 to do some cutting on the root itself. 
 
TRIMMING OF THE TEETH 
 
 105 
 
 The bulk of this enamel can always be removed with scalers 
 or enamel cleavers, and it is very rarely that any other instruments 
 need be used. 
 
 The most useful instruments for this purpose are an enlarged 
 special No. 3 scaler (Fig. 114) and also the Xo. 7 scaler, which is 
 of a slightly different shape and much thinner (Fig. 115). 
 
 Fif;. 117. — Shows the trimming of the labial and aproxiinal sides of the rifiht 
 
 fuspid root. 
 
 The.se instruments .should have large handles in order that 
 the operator may hold them with a firm grip and have perfect control 
 of the instrument so that there is no possibility of its slii)ping, or 
 twisting in the hand, and injuring the soft tissues. The heavy 
 handles shown in the illustration will be found mo.st suitable for 
 u.se with these trimmers (Fig. 114). 
 
 Trimming the RooIh of the Upper Anterior Teeth. — In working 
 oil the upper anterior roots, the instrument is grasped in exactly 
 the same manner as a knife is held in shari)eiiiiig a pencil, the only 
 
106 
 
 TYPICAL SHAPES OF THE TEETH 
 
 difference being that instead of resting on the ball of the thumb, 
 the end of the thumb is placed against an adjoining tooth, as in 
 Figs. 116 and 117, and the force exerted to strip the enamel from 
 the root by a slight opening and closing movement of the hand. 
 The special scaler (Fig. 1 14) is of such shape that it closely follows 
 the contour of the root. It is passed down below the gum line, 
 crowding the gum away from the root until it goes beyond the 
 enamel which is thus stripped off until the root is perfectly smooth. 
 
 Fig. 118. — Shows the trimming of the lingual portions of the left cuspid root, 
 the thumb of the hand holding the instrument, resting on the thumb of the left 
 hand. 
 
 In cases where the stump may stand by itself, and there is no 
 adjoining tooth on which to secure a rest; especially if the gum 
 be somewhat tender, the thumb or finger of the other hand may be 
 placed on the gum with the end of the thumb of the hand holding 
 the instrument resting against it (Figs. 118 and 119). 
 
TRIMMING OF THE TEETH 
 
 107 
 
 As we go farther back in the mouth, especially if the mouth be 
 small and the cheeks tense, there will be times when it will be 
 impossible to hold the instrument in the manner described. Then 
 it may be necessary to grasp the instrument firmly in the right 
 hand, and exert the force to strip the enamel with the thumb or 
 finger of the left hand. The illustrations give a fair idea of the 
 manner in which this is done (Figs. 120 to 125). 
 
 Fig. lip, — Shows trimmiriK of the labial side of loft cuspid, instrument and hands 
 in same position as in Fig. 118. 
 
 Trimming the Hoots of the Lower Anterior Teeth. — Trimming the 
 roots of the lower aJiterior teeth is much more difficult than is the 
 trimming of the roots of the upper and the dift'erent portions of 
 the roots are far more difficult of access. It is impossible to hold 
 the instruments in the maimer in which they are held in trimming 
 the upper roots. The same instruments are used, however, the 
 operator standing at the back, and to the left of the patient, the 
 
108 
 
 TYPICAL SHAPES OF THE TEETH 
 
 chair being in its lowest position. The instrument is held in the 
 right hand, and as nearly on a line with the long axis of the tooth 
 as possible. 
 
 The fingers which are not used in holding the trimmers are 
 braced against the teeth or some part of the upper jaw, so that 
 there will be no possibility of the operator losing control of the 
 instrument and injuring the tissues. The principal force is exerted 
 with the thumb and finger of the left hand, that of the right being 
 used only to steady and to give a pull to the instrument. 
 
 Fig. 120. 
 
 -Shows trimming of right second bicuspid from buccal side, thumb of 
 right hand resting on thumb of left hand. 
 
 In trimming the buccal or labial surfaces of the teeth on the 
 right side of the mouth and around to the median line, the force 
 used in stripping the enamel is exerted by the first finger of the 
 left hand, the thumb being braced on the lingual side of the tooth 
 or jaw and in such a manner that it will not be struck by the point 
 of the instrument. The instrument is passed beneath the enamel 
 
TRIMMING OF THE TEETH 
 
 109 
 
 and pressed tiglitly against the root, while the pull is being exerted 
 with the right hand, as shown in Fig. 126. Nearly all of the mesial 
 and distal sides of the teeth may also be reached by working the 
 instrument in the same wav. 
 
 Via. 121. — Shows nearly same position, but part of the force for stripping llic inaniol 
 exerted by thumb of left hand. 
 
 On trimming the lingual side of these teeth, the force is 
 exerted by the thumb of the left hand and the fingers are braced 
 on the buccal c^r labial side of the teeth (Fig. 127). In trimming 
 the teeth on the left side of the mouth, these methods are reversed, 
 the thumb being used to exert the force when working on the buccal 
 
no 
 
 TYPICAL SHAPES OF THE TEETH 
 
 or labial sides of the roots and the fingers when working on the 
 lingual (Figs. 128 and 129). 
 
 On the mesial and distal sides, the force is applied the same as 
 for the buccal and lingual, either the thumb or finger being used 
 as is most convenient. 
 
 Where the operator is left-handed, the method of operating 
 and the manner of holding the instrument would be reversed. 
 
 Fig. 122. — Shows trimming buccal corners of upper left molar, force exerted by first 
 
 finger of left hand. 
 
 The enlarged special scaler (Fig. 114) is used on the labial or 
 lingual sides of the root and if there is sufficient room between it 
 and the other teeth it can be used on all sides; but if there are adjoin- 
 ing teeth so close as to prevent this, then the smaller scaler (Fig. 
 115) is used on the mesial and distal sides. 
 
 The scaler (Fig. 114) is the most universal, and can be used in 
 almost every position where there is sufficient space between the 
 teeth. 
 
TRIMMING OF THE TEETH 
 
 111 
 
 At times the enamel, principally of the cuspids and especially 
 on the lingual side, is so heavy and so very firmly attached to the 
 dentin that it is impossible to start it with these instruments, in such 
 cases, the Case enamel cleavers may be used to start with, and 
 afterward the finishing is done with Xo. 3 scales. 
 
 Fig. 12.3. — Shows trimming of lingual corners of upper left molar, force exerted by 
 
 thunil) of left hand. 
 
 Tlie C'a.se enamel cleavers (Fig. 130) have a strong sharp bit, 
 and are very useful when a great deal of force is necessary. Their 
 shape is sueli, Iio\v('\(t, that they do not leave the root smooth; the 
 surface from wliicli they have stripjx'd the enamel is left in grooves 
 and ridges, s(; that it is necessary to follow them with Xo. 3. 
 
 \t times, even these instruments will not break the enamel, and 
 it becf)mes neeessar\' to start its remoNal with small carborundum 
 points or diamc^nd wheels, finishing with the Xo. 3 scaler. 
 
112 TYPICAL SHAPES OF THE TEETH 
 
 FACING ROOTS FOR VARIOUS FORMS OF CROWNS. 
 
 It has already been said that the stump should be left standing 
 for a considerable distance out of the gum, until after the root has 
 been trimmed and the band fitted. 
 
 Richmond Crowns. — In the case of a Richmond crown, after the 
 root has been trimmed, the band fitted, and the canal enlarged. 
 
 Fig. 124. 
 
 -Shows trimming of buccal corners of upper right molar, force exerted by 
 thumb of left hand. 
 
 the stump is cut away labially to from one-thirty-second to one- 
 sixteenth of an inch below the gum margin, so that when the 
 crown is completed the band will be entirely hidden. Lingually, 
 if the bite will permit, it may be left standing from one-thirty- 
 second to one-sixteenth of an inch out of the gum, so as to give 
 
FACING ROOTS FOR VARIOUS FORMS OF CROWNS 113 
 
 additional support and strength to the crown, cutting the stump 
 in a straight hne from the hngual to the kibial side (Fig. 111). 
 This will apply to single crowns or those used as abutments for 
 fixed bridges. 
 
 Fig. 125. — Sho.'... lumuiing of lingual corners of upper right molar, force exerted 
 by forefinger of left hand. 
 
 Porcelain or Downie Crowns. — For a porcelain crown a double slope 
 is given to the root. The root is cut labially to the same depth 
 below the gum as for a liichmond crown, but lingually it should 
 be carried just to the gum border, leaving it high in the center. 
 
 The reason for this double bevel, instead of making it straight 
 
 across from buccal to lingual, is that it is necessary to festoon the 
 
 lower edge of the band to follow the gum line, and also to allow for 
 
 a greater bulk of porcelain in order to give increased strength. 
 
 8 
 
114 
 
 TYPICAL SHAPES OF THE TEETH 
 
 The septum of the process comes much higher up on the root 
 mesially and distally than it does at the buccal and hngual sides 
 of the teeth, and therefore it is necessary to festoon the band 
 accordingly (Fig. 131). 
 
 Fig. 126. — Shows trimming buccal side of lower teeth, on the right side of the mouth, 
 force exerted by finger of left hand. 
 
 If it were cut straight across, in order to place a perfectly flat 
 floor on the band, the band would be cut entirely away mesially 
 and distally, as shown in Fig. 132. As previously stated, the strength 
 of porcelain is only in proportion to its bulk. For the purpose of 
 illustration, we will exaggerate the figure somewhat, so as to make 
 clear the reason for preparing the roots in the manner described. 
 
FACING ROOTS FOR VARIOUS FORMS OF CROWNS 115 
 
 We will suppose the case of an upper bicuspid crown where the 
 bite is fairly close. It will be noticed that by giving? a direct slope 
 from the buccal to the lingual side, as would be done if it were a 
 Richmond crown, that when the facing has been ground in place 
 and the lingual side of the tooth built up with porcelain, it 
 
 Fig. 1:^7. — Shows trimming linguiil side of lower teeth on the right side of mouth, 
 force exerted by thumb of left hand. 
 
 would render it very weak on that side, and would be quickly 
 crushed, as there is so very little porcelain to give strength 
 (Fig. i:«). 
 
 If it were a Richmond crown where a gold back was to be used, 
 then of r-ourse it would not make the slightest difference, as a small 
 
116 
 
 TYPICAL SHAPES OF THE TEETH 
 
 bulk of gold at this point would give far greater strength than would 
 be possible if it were made of porcelain. 
 
 It will be seen that if the tooth is cut away to the gum line, so 
 as to give it a double slope to the stump, that a much greater bulk 
 of porcelain could be used with a corresponding increase in the 
 strength of the crown (Fig. 134). 
 
 Fig. 128.- 
 
 -Shows trimming of buccal side of lower teeth on left side of the mouth, 
 force exerted by thumb of left hand. 
 
 The facing of the roots may be done with a square-edged car- 
 borundum wheel, but this necessitates an unnecessary mutilation 
 of the gmn tissue. The best instruments for this purpose are the 
 Ottolengui root facers (Fig. 135). These instruments are made in 
 different sizes to correspond with the different teeth, and will 
 do the work perfectly with but little or no mutilation of the soft 
 tissue. 
 
FACING ROOTS FOR VARIOUS FORMS OF CROWNS 117 
 
 As these instruments come from the dental depots, the guide 
 point is very much longer than it should be, unless the root is to 
 be faced perfectly flat and at right angles with the canal. If, in 
 order to slope the face of the root in either direction, the instrument 
 
 Fk;. 129. — Shows trimming lingual side of lower teeth on left side of the mouth, 
 force exerted by finger of left hand. 
 
 is inclined either labially or lingually, and unless the canal be very 
 much enlarged the end of the point will strike the opposite wall of 
 the canal so as to prevent the instrument facing tlie tooth on an 
 angle, as will be seen in the illustration (Fig, 136). This point should 
 
118 
 
 TYPICAL SHAPES OF THE TEETH 
 
 be ground off so that its length is about the same as its diameter, 
 and then there will be no trouble in sloping the face of the root in 
 
 Fig. 130. — Enamel cleavers. 
 
 the desired direction (Figs. 137 and 138). If the root is much 
 decayed and enlarged at the entrance to the canal, the length of 
 the pin will make little difference. 
 
 Fig. 131 
 
 Fro. 132. 
 
 Fig. 133 
 
 Fig. 134 
 
 In using these instruments, it will frequently be found that a 
 facer, which is large enough to cover the root mesially and distally, 
 will not reach the lingual and buccal sides. 
 
 I ■ 
 
 Fig. 135. — Root facers. 
 
 Fig. 136 
 
 Fig. 137 
 
 Fig. 138 
 
 Fig. 139 
 
FACING ROOTS FOR VARIOUS FORMS OF CROWNS 119 
 
 After the floor has been united to the })and and phiced on the 
 root, it may be that it does not go under the gum so as to be hidden. 
 On removing the cap and examining the root, it will be seen that 
 the facer has left a little ridge of dentin on the labial side which 
 has prevented the band from going to place (Fig. 188). Where 
 such is the case, by reaming the canal a little labially or lingually 
 as shown by the illustration (Figs. 137 and 139), and enlarging the 
 entrance to the canal to a slight depth, it will allow the facer to 
 cover the root at both of these places. 
 
CHAPTER VII. 
 
 IMPRESSIONS AND MODELS. 
 
 An impression for a working model on which a crown or bridge 
 is to be made should always be taken in plaster. Modeling com- 
 position, wax or any of the plastic materials which are used for 
 taking impressions should not be used for a working model, as there 
 is no plastic impression material made which will give an accurate 
 impression where there are undercuts or dovetailed spaces. The 
 material will draw and drag, and become distorted on removing 
 it from the mouth, with the result that the model made from such 
 an impression will be imperfect. 
 
 IMPRESSION AND MODEL PLASTER. 
 
 A first class impression plaster should be fine and quick setting, 
 thus rendering the impression soft and easily cut away from the 
 model in separating. 
 
 A good model plaster, on the contrary, is coarse and slow setting, 
 and becomes very hard. 
 
 The difference between a good impression plaster and a good 
 model plaster can be instantly determined by rubbing it between 
 the fingers. The impression plaster will be fine and smooth like 
 flour between the fingers, while the model plaster will be coarse 
 and the grit is plainly felt. 
 
 If so situated that it is difficult to secure the different grades of 
 plaster, it is better to procure the hardest model plaster that it is 
 possible to get. Then, by bolting this through a fine cloth a good 
 impression plaster will be secured, in the finer material which passes 
 through the cloth, and at the same time, by removing this fine 
 plaster, the model plaster will be improved. It will be slower 
 setting, and its hardness increased, 
 
 WEINSTEIN'S ARTIFICIAL STONE. 
 
 This new material (a calcium barium silicate) is eminently 
 suitable for making models and articulations for bridgework, 
 
 (120) 
 
WEINSTEIN'S ARTIFICIAL STONE 121 
 
 vulcanite work, and other purposes, where a stronger and more 
 durable material than plaster of Paris is required. INlodels made 
 from it are remarkably hard and durable and not friable, like 
 plaster of Paris or any of the Portland cement preparations. 
 
 Another most valuable property of the artificial stone lies in the 
 fact that it possesses practically no expansion or contraction. 
 Upon periodic examination of a number of specimens under test 
 for a year, no measurable change was found after the initial set 
 had taken place. It contains no gritty or coarse particles and 
 models made of it are very dense and smooth. 
 
 The following instructions for manipulating artificial stone are 
 given by Mr. Weinstein: 
 
 Proportions for Mixing. — Accurate proportioning of the powxler 
 and the water that it is mixed with is imperative, and the results 
 far more than repay the little effort that it takes to weigh out the 
 powder and measure the water. For an upper or lower model, the 
 following proportions are suitable: To 1| fluidounces of water 
 add 78 to SO dwts. (Troy) of the artificial stone powder. 
 
 The mixing is done in a rubber bowl, first incorporating approx- 
 imately one-half of the powder, and gradually adding the balance, 
 until all the powder is thoroughly incorporated. If the propor- 
 toins taken are correct, the mass will be as stiff as a very thick mix 
 of plaster. 
 
 Preparation of Impressions. — The impression, if plaster, should be 
 \arnished with one coat of shellac, which should be allowed to dry 
 for at least one-half hour, and then varnished with a coat of san- 
 darac, which should be allowed to dry for at least one hour. The 
 impression should then be immersed in water for at least five 
 minutes, so that it may become thoroughly saturated. It is then 
 removed and the excess water blown off with compressed air or 
 wiped off with cotton, leaving the surface of the impression moist, 
 but not wet. It is important that this be strictly observed, as a 
 dry impression will absorb moisture from the artificial stone, while 
 it is setting and produce a poor model. Modeling compound, or 
 wax imi>rcssions rcf^uire no special treatment. 
 
 Filling Impressions. — As the artificial stone is mixed quite thick, 
 it cannot be poured like plaster, but must be brushed or packed 
 carefully into all deep parts before filling in the bulk to l)uil<l up a 
 model. To facilitate the placing of the material into deep crevices 
 or depressions, such as are found in an impression of a case with 
 standing teeth, the following suggestion will prove helpfiil : i)repare 
 
122- IMPRESSIONS AND MODELS 
 
 mix according to proportions given; take off about one-half tea- 
 spoonful, place it in the palm of the hand, or on a cement slab and 
 incorporate with it some additional powder until it becomes as 
 stiff as putty. Prepare from this small mix a number of small 
 cones, lay them aside; work down some of the regular mix into the 
 deep recesses, using a small brush or other means, then place a 
 cone into each depression and tamp dow^n with a small stick or the 
 eraser end of a lead pencil. This will serve to force the plastic mix 
 into all inaccessable places. The balance of the impression may 
 then be filled in practically the same manner as in manipulating 
 a thick mix of ordinary plaster. As this material sets quite slowly, 
 ample time may be taken to fill the impression carefully. 
 
 Separating Impression. — The filled impression should be permitted 
 to set at least four hours prior to separating; however, it should not 
 be allowed to stand more than twelve or fifteen hours before sepa- 
 rating as the hardness gradually increases, making it more difficult 
 to do the required trimming. 
 
 The model will become as hard as well-set plaster of Paris within 
 six or seven hours after pouring, and may then be used if necessary. 
 The maximum hardness is attained within thirty-six to forty-eight 
 hours. 
 
 IMPRESSION AND BITE. 
 
 In order to secure perfect results, the model on which the bridge 
 is to be constructed must be as nearly perfect as it is possible to 
 make it. The impression must be clear and sharp, so that the caps 
 and bands, which have been in position in the mouth when the 
 impression was taken, will fit accurately into place. 
 
 It is necessary that the articulation should be as perfect and 
 accurate as is the model. These results can best be secured by 
 taking what is known as a "squash bite," that is, taking the 
 impression and bite simultaneously in plaster and by so doing 
 far better results will be obtained than it is possible to secure in 
 any other way. 
 
 In taking the impression and bite in this manner, the plaster is 
 allowed to become quite hard and is then carefully broken away 
 and afterward the broken parts are easily assembled, and the 
 model secured from this will be a perfect reproduction of the 
 required part of the mouth. 
 
 It is the general custom to take the impression for this work in 
 the ordinary manner, using a tray for the purpose. A separate 
 
COLORING AND FLAVORING IMPRESSION PLASTERS 123 
 
 bite is afterward taken in wax or modeling composition and the 
 model prepared from this. It is not possible to secure anything 
 like the accuracy, in taking the impression and bite in this manner, 
 as it is by taking the squash bite in plaster. 
 
 The model is first cast, and after it has become hard and has 
 been separated the waxed bite is pressed into place. It generally 
 happens that this bite has to be trimmed more or less in different 
 places before it can be pressed into position. The wax being hard, 
 considerable pressure is necessary and it is liable to be forced 
 farther down on the model in one place than in another, with the 
 result that the articulation is not exactly as it should be. Then, 
 after the bridge is completed, it is necessary to do more or less 
 articulating when it is adjusted in the mouth. This necessitates 
 taking the piece to the laboratory for refinishing. 
 
 Where a plaster impression and articulation has been taken in the 
 manner described, it is possible to construct a bridge and finish it so 
 that when it is placed in the mouth the occlusion will be so nearly 
 perfect it will rarely be necessary to do any grinding at all. 
 
 COLORING AND FLAVORING IMPRESSION PLASTERS. 
 
 It is an excellent idea to tint the impression plaster slightly, as 
 this difference in color from the model will very materially aid in 
 separating the impression from the model. Another good plan is to 
 flavbr the plaster slightly. It has been the custom of the waiter 
 for many years to tint the impression with carmine, and also to use a 
 few drops of cologne in the water in which the plaster is mixed. This 
 cologne not only imparts an agreeable flavor to the plaster, but in 
 many instances it will entirely overcome the nausea to which some 
 patients are subject when plaster is placed in the mouth. It has 
 been iouud that in many instances, where it has been impossible 
 to get a plain plaster impression without the patient l)ecoming 
 nauseated, that these few drops of cologne water will entirely 
 prevent it. 
 
 The method of j^reparing the carmine and cologne solution is as 
 follows: A half ounce bottle is filled about one-quarter full with 
 carmine, and the bottle then filled up with strong ammonia, this 
 being the only agent available that will thoroughly dissolve it. 
 This solution is well shaken until the carmine is all dissolved. The 
 bottle is then left unstoi)pered for a day or two, until the fumes of 
 arnrnoiiia have jiassed ofl'. 
 
124 IMPRESSIONS AND MODELS 
 
 About one-fifth to one-quarter of this carmine solution is put in 
 a six ounce bottle and the bottle filled with cologne and this gives 
 us the coloring and flavoring solution. A few drops of the solution 
 is added to the water in which the plaster is to be mixed, thus 
 giving it the color and flavor desired. The cologne used should be 
 an alkaline solution, as should it be acid it would precipitate the 
 carmine. 
 
 The setting of the plaster may be hastened in many ways, and 
 it is generally desirable that this be done in taking impressions. 
 It may be accomplished by mixing the plaster with warm water 
 or bv adding to the water a little common salt, or potassium sul- 
 phate. Much stirring also will have the same result. The pro- 
 portions of water and plaster used will also accelerate or retard 
 the setting. The writer prefers the potassium sulphate for this 
 purpose, as very little will accomplish the purpose, and it does not 
 impart a disagreeable taste to the mixture as is the case where the 
 salt is used. 
 
 The amount used depends on the size of the impression which 
 is to be taken. If this be small, we can use proportionately more 
 than we could for a large impression, as a longer time is required 
 to spread the plaster in the mouth for a large impression than it 
 does for a small one. In the case of a full impression, very little 
 should be- used, and at times none at ah. The amount used, how- 
 ever, will depend upon the particular batch of plaster with which 
 we are working, as there is hardly any two lots of plaster which will 
 work exactly alike, some setting much more quickly than do others. 
 Iia getting a new supply of plaster, it is always best to make one or 
 two mixes, before using it in the mouth, in order to become familiar 
 with its properties. 
 
 To get the best results for impressions, the plaster should also 
 be thoroughly mixed. The method of mixing is as follows: First 
 place a little of the potassium sulphate in the bowl, adding a few 
 drops of the carmine and cologne solution, and then as much water 
 as is needed for the impression under consideration. The plaster 
 should never be thrown in the bowl carelessly and in large quantities, 
 but should be sifted into the water carefully and in small quantities, 
 taking it on the spatula and sifting it round the edges of the bowl. 
 The plaster will work toward and settle in the center so that there 
 will be no air confined in a mass of dry plaster. 
 
 The plaster should be added slowly until it comes just about to 
 the surface of the water, but not enough is used to take up all the 
 moisture. This is then carried to the chair without stirring. By 
 
TAKING IMPRESSION WITH ABUTMENTS IN PLACE 125 
 
 refraining from stirring the mix, the plaster does not begin to set 
 and it will give some little time in order to examine the mouth and 
 see that everything is all right, the caps in position, etc. After it 
 has been ascertained that everything is as it should be, begin mixing 
 the plaster, stirring it with the flat of the spatula and cutting through 
 the mass with the spatula held edgewise to work out the air bubbles. 
 The stirring should be kept up until the plaster is just stiff enough 
 so that it will not drop from the blade of the spatula when it is 
 inverted. It is then ready for use in the mouth. 
 
 TAKING THE IMPRESSION WITH ABUTMENTS IN PLACE. 
 
 First cover well with the plaster the bands or caps on the abut- 
 ments, and then fill in the spaces between the abutments, and also 
 taking in several of the adjoining teeth. The occlusal surfaces of 
 the occluding teeth are also covered with the plaster. 
 
 The patient is then instructed to close the mouth tightly and 
 the teeth which have not been included in the impression are care- 
 fully examined to see if the proper closure has been obtained. 
 
 Securing the Proper Closure. — At times it is very difficult to get 
 the patient to close the mouth properly on a mass of plaster or wax. 
 There are many different ways of inducing the patient to give the 
 proper bite, such as having the patient swallow, throwing the head 
 far back while closing the mouth, and at times even using force to 
 throw the chin back where it belongs. 
 
 The writer has frequently found that where every other method 
 would fail, a proper occlusion could be secured if the patient would 
 turn the tip of the tongue as far back on the soft palate as possible 
 and hold it there while bringing the jaws together. It will be 
 found that it is impossible for a patient to give a wrong closure if 
 the tongue is held in this position until the jaws are closed, as the 
 chin cannot be thrust forward or from side to side without moving 
 the tongue. 
 
 The impression should be left in the mouth until the plaster has 
 become thoroughly hard and brittle. This is ascertained by testing 
 from time to time the plaster remaining in the bowl. As soon 
 as it breaks with a clean, sharp fracture, and when a small particle 
 rubbed between the thumb and finger cannot be crushed, the 
 impression will be sufficiently hard to be removed from the mouth, 
 but as long as the plaster can be crushed between the thumb and 
 finger and moisture squeezed from it, it should not be removed. 
 
126 IMPRESSIONS AND MODELS 
 
 When it has thoroughly hardened, the patient is instructed to 
 
 open the mouth, and the impression is carefully removed, every 
 
 broken particle being saved. It is very rarely that an impression 
 
 taken in this manner will come away whole, but will be more or 
 
 less broken up, sometimes in many pieces. It is well to have a little 
 
 tray with the bottom covered with a piece of blotting paper, on 
 
 which to lay the impression. The broken parts, as they come from 
 
 the mouth, should be so placed on the tray that it can be remembered 
 
 where they belong. This will render much easier the task of putting 
 
 together the broken impression. 
 
 The caps and bands are then removed from the abutments. If 
 
 any of the abutments are in the anterior part of the mouth where 
 
 bands are supposed to be hidden, the stumps should be protected. 
 
 This can generally be done by simply taking a piece of 
 
 base plate gutta-percha and rolling it something in the 
 
 shape shown in Fig. 140. The root is then thoroughly 
 
 dried, the gutta-percha slightly heated and the small end 
 
 ^^„ introduced into the canal. The bulbous portion is then 
 Fig. 140 , ^ 
 
 pressed over the face of the root carrying it well over the 
 edge and forcing the soft tissues away. This will prevent the gum 
 from growing over the face of the root, and will render the 
 subsequent placing of the band or cap much easier than it would 
 otherwise be. 
 
 At times a large-headed tack may be used for this purpose. 
 The point of the tack can be shortened, so as to allow the head to 
 come flush with the gum line. The shank is covered with base 
 plate gutta-percha, and it is then warmed and forced into the 
 root and the surplus gutta-percha carried over the head of the 
 tack, so that the metal will be covered (Fig. 141). 
 
 Treatment of Impression, — After the impression has been removed 
 from the mouth, it should be left on the blotting paper for from 
 fifteen to twenty minutes, so as to allow the excess moist- 
 ure to be absorbed, but not long enough to dry the plaster, 
 as the impression can be put together more easily and 
 quickly, and also more accurately, if the impression is a 
 little moist. The parts are then carefully assembled and fig. 141 
 fastened together with a strong wax. The wax for this 
 purpose should be sticky, tough and sufficiently hard that it will 
 not bend in the handling. 
 
 The writer has found that the following formula will make the 
 best wax for this purpose: 
 
TAKING IMPRESSION WITH ABUTMENTS IN PLACE 127 
 
 Pure white beeswax 16 ounces. 
 
 Pure white resin (powdered) 3 ounces. 
 
 Gum Damar (powdered) 3 ounces. 
 
 It should be melted in the order given, and well stirred until 
 the powdered resin and gum damar are thoroughly incorporated 
 with the wax. It can be poured in cups or moulds, or rolled into 
 sticks of any desirable size or length. 
 
 The ordinary dark beeswax and dark resin, may be used in making 
 the wax, but it does not make a hard wax that is as clean and nice 
 to work as does the white. We must be certain, however, that the 
 beeswax is perfectly pure. If there should be the slightest trace of 
 paraffin in it, the wax made from it will be worthless. 
 
 After the impression has been put together, the caps and bands 
 are put back in it in their original positions, care being taken to 
 see that they fit exactly into place. They are then waxed firmly 
 in the impression with sticky wax. In the case of an anterior abut- 
 ment where we have a cap and tube, the cap is held in position firmly 
 with the instrument, and the edges of the band are waxed tightly 
 labially and lingually (Fig. 142, points a and b) before waxing it on 
 the sides, thus holding the caps immovable while the sides are being 
 waxed. If we attach it in one place only at first, say on the lingual 
 side of the cap, the contraction of the wax on cooling is liable to 
 draw the cap away from the impression labially, thus giving to it a 
 false position, so that, after the model is made and the bridge com- 
 pleted, it will be found that it will not go in the mouth as it should. 
 
 The edges of the caps standing out of the impression are waxed 
 heavily on the outside with hard, sticky wax (Fig, 143). This will 
 not only hold the band in place, but will also help to hold the 
 impression together. The inner side of the cap is covered with a 
 very thin film of pink paraffin wax. In the case of a cap for a 
 
 p .n- cz. -n 
 
 I-'k;. 142 V\(i. 143 Fiu. 144 Fig. 145 
 
 shell crown, or where the band is larger at the occlusal end (Fig. 
 144), enough wax should be put on the inside of the band to 
 obliterate aii>- undercuts or do\'etai)ed spaces (Fig. 145). If there 
 arc i)ins or tubes in the caps they should also be covered lightly 
 witli the paraffin and wax. 
 
128 IMPRESSIONS AND MODELS 
 
 The gingival edge of the band should be scraped clear of wax, 
 so that it will set down tightly to the model. The obiect in having 
 the outer edges of the band covered thickly with wax we will now 
 explain. 
 
 If we put but a thin film of wax around the outer edge, as we do 
 on the inside of the band, it will be noticed that after the model 
 has been made and the band removed, that the^e is a fine groove 
 in which the gingival end of the band rests (Fig. 146). The result 
 will be that after taking off and putting on the cap a few times, 
 some of the plaster may be scraped from around the sides of the 
 stump which, working into the groove, will fill it partially, with 
 
 Fig. 146 Fig. 147 Fig. 148 
 
 the result that by the time the crown is completed, the band may 
 not go nearly as far beneath the gum as it was originally intended 
 that it should (Fig. 147); whereas, if it is waxed heavily on the out- 
 side, when the band has been removed, the wax is stripped away, 
 leaving a wide groove on the model around the stump, so that if 
 any plaster is scraped from the model and gets into the groove, it 
 is quickly noticed and easily removed (Fig. 148). 
 
 Separating Medium. — Different materials are used for this purpose 
 such as soap, oil, shellac, or sandarac varnish, or shellac and san- 
 darac varnish combined. Oil is a very good separating medium 
 but the surface of a model cast in an oiled impression is never as 
 hard as it should be, and it is also more liable to be porous. The 
 same may be said of soap, as a separating medium. It makes 
 separating the impression from the model very easy, and will give 
 a clear-cut, sharp-outlined model, but as in the case of the oiled 
 impression, the surface of the model will not be ver^^ hard. If soap 
 is used, after using, the impression should be thoroughly washed 
 with clear water, otherwise there will be bubbles and a porous 
 surface which wi]l render the model unfit for use. 
 
 Shellac is used by many to first color the impression, which is 
 then given a coating of sandarac varnish. The use of both of these 
 varnishes is unnecessary, as, if the sandarac varnish is slightly 
 colored, it will accomplish the object. The varnish can be colored 
 with various dyes, but a very simple way is to scrape a little of the 
 
TAKING IMPRESSIONS IN SECTIONS 129 
 
 crayon of an indelible pencil into the varnish, this on dissolving 
 will impart to it a purple color. <^ 
 
 The impression, which is varnished until it has a glazed surface, 
 will give a model with a much smoother and harder surface than 
 it is possible to secure by using soap or oil. However, the varnish 
 should not be so thick as to obliterate the fine lines which we wish 
 to preserve in the model. 
 
 The impression should be moist in order to take the varnish and 
 leave a glazed surface. If it is placed on a blotting pad and left 
 for fifteen or twenty minutes after the impression has been removed 
 from the mouth, it is generally in the right condition to take the 
 varnish best. If the model is too dry, the varnish Avill soak in and 
 not give a glossy surface. If the impression stands for some hours 
 after taking before assembling and varnishing, it will have become 
 too dry, and should be dipped in water and then placed on a blotter 
 for a few minutes, before varnishing. If the model is too wet the 
 varnish will not stick, but will roll up and scale off. 
 
 As soon as the varnish has hardened, which will be in four or five 
 minutes, the impression can be dusted with talcum powder, w^hich 
 is afterward blown out with a chip blower. This will render the 
 separation of the impression and model very much easier. 
 
 TAKING IMPRESSIONS IN SECTIONS. 
 
 At times it is desirable to secure an impression where the teeth 
 are very much loosened, and where it w^ould be impossible to obtain 
 an impression in an ordinary tray, with any material, without risk 
 of removing the teeth with the impression, and also causing the 
 patient considerable pain. 
 
 There are times when some of the lower incisors may be so loose 
 that it would be possible to remove them easily with the thumb 
 and finger, yet it is desirable to retain them in position for a time, 
 with some kind of a splint. By taking the impression for a case of 
 this kind in sections, it can be done without the pain to the patient, 
 nor the slightest danger of removing the teeth. 
 
 The plaster is prepared and mixed the same as described for 
 taking an impression and bite simultaneously. The teeth are 
 pressed into their proper position and held so with one of the 
 fingers of the left hand (Fig. 149). With the aid of a spatula 
 the plaster is placed on the lingual side of the teeth and smoothed 
 off, letting it extend a little above the iiuisal edge. 
 9 
 
130 
 
 IMPRESSIONS AND MODELS 
 
 After the plaster has hardened, the finger is removed from the 
 labial side, the plaster holding the teeth firmly in place. The 
 plaster is then trimmed flush with the incisal edges, beveled on the 
 lingual side and then slight grooves are made in one or two places 
 to serve as guides in putting the sections together (Fig. 150). This 
 is now covered with a separating medium and for this purpose a 
 soap solution is most convenient. 
 
 Fig. 149 
 
 A fresh mix of plaster is then made, and the labial side of the 
 teeth is covered heavilv, the plaster being carried over the incisal 
 edges, and over the beveled portion of the plaster impression on 
 the lingual side (Fig. 151). It is then left until it has become quite 
 hard. The labial side of the impression is then pried away, forcing 
 it outward and upward, after which the lingual side is carefully 
 removed. 
 
 These two halves are then put together and waxed, and we have 
 
TAKING IMPRESSIONS IN SECTIONS 
 
 131 
 
 as perfect an impression as it is possible to secure (Fig. 152), giving 
 the interspaces between the teeth, which cannot be gotten by any of 
 the ordinary methods of impression taking. When the model has 
 been made from this impression, it gives an exact reproduction of 
 the teeth in their normal position, from which a splint or retaining 
 bands can be made. 
 
 Fig. 150 
 
 Fig. 151 
 
 Fig. 152 
 
 This method of impression taking may also be employed to 
 advantage in any case where there are dovetail spaces or deep 
 undercuts. It is also valuable in securing accurate models for 
 orthodontic or other purposes, or in the reproduction of models. 
 When it is desirable to get a very accurate impression of a lower 
 jaw, where the teeth are inclined very much lingually, or where there 
 are do\'etail interspaces from which teeth have been lost, by this 
 method impressions of the greatest accuracy are easily obtained. 
 
 Fig. 153 
 
 In securing a full impression, the lingual sides of the teeth are 
 first covered, the plaster being carried well down over the gum, 
 and then smoothed so that the sides will slope away from the sides 
 of the teeth the same as a core on an undercut model in getting a 
 mould for casting a die (Fig. 153, a and h). The upper side is 
 trimmed, preferably, about one-thirty-second of an inch below the 
 occlusal surfaces of the teeth. The plaster is then given a coating 
 
132 
 
 IMPRESSIONS AND MODELS 
 
 of the soap solution, and an impression taken over this, using an 
 ordinary tray, carrying it well down over the plaster which has 
 been placed on the lingual sides of the teeth (Fig. 154). 
 
 Fig. 154 
 
 After the impression has hardened, the tray is removed together 
 with the impression, leaving the plaster cores first placed on the 
 lingual sides of the teeth, still in the mouth (Fig. 153, a and b). 
 These pieces are then pried away and placed back in the impression 
 in the tray (Fig. 155). 
 
 Fig. 155 
 
 A full and perfect impression of the mouth has thus been secured 
 from which a much more accurate model can be made than it is 
 possible to obtain from an impression taken in the ordinary manner. 
 
 Fig. 156 
 
 Fig. 157 
 
 This method will also be found very useful where an exact reproduc- 
 tion of a plaster model is desired. 
 
ARTICULATORS 133 
 
 An impression of dovetailed interspaces, from which teeth have 
 been lost (Fig. 150), can easily be obtained by putting plaster first 
 on the lingual side of the teeth, and letting it come to about half 
 way through the space to the buccal side. This is smoothed off, 
 covered with a separating medium, and filled in from the buccal 
 side (Fig. 157), and an impression taken over that in a tray in 
 the manner already shown in Fig. 154. 
 
 ARTICULATORS. 
 
 In crown and bridge-work, the question of occlusion is of most 
 vital importance, as the stability and life of the work depends to 
 a very great extent upon its proper occlusion with the opposing 
 teeth. 
 
 In all extensive cases of bridge-work, it is absolutely essential 
 that only first-class anatomical articulators, capable of reproducing* 
 the natural, lateral or triturating movements of the mandible, so 
 necessary for perfect mastication, should be used. For single 
 crowns, and at times for small bridges, it is permissible to use some 
 other type. 
 
 Nearly all of the small, so-called crown articulators on the market 
 are absolutely worthless so far as securing good results are con- 
 cerned. \yith these articulators, the only movement possible is 
 simply the up and down, or opening and closing movement of the 
 mandible. Of late, a few small articulators have been placed on 
 the market which are capable of imitating the various movements of 
 the lower jaw. 
 
 A plaster articulator, if it is properly made, will give excellent 
 results for single crowns and also for small bridges, and the manner 
 of making such articulations will be described further on. 
 
 In making an entire denture, the matter of occlusion is of especial 
 importance, and the difficulty of securing an accurate occlusion 
 is far greater than where only a portion of the teeth are to be 
 restored. If a full bridge is to be made for the upper jaw, and the 
 majority of the teeth in the lower jaw are in place, the attachments 
 for the molars can be made and if properly articulated will then 
 serve as a guide in getting the bite, or the occlusal surfaces of 
 these teeth may be built up with cement so as to interlock with 
 the lower teeth, and open the bite to the proper distance. 
 
 In the majority of these cases, the impression and bite should 
 be taken in plaster, the same as in smaller cases, and the face-bow 
 
134 IMPRESSIONS AND MODELS 
 
 should be used to serve as a guide to mount the models properly 
 on the articulator. The semicircular plate, to which the stem of 
 the face-bow is attached, is pressed in the soft plaster as soon as 
 the patient has closed the mouth and the upper surface of the disk 
 partially freed from the plaster, as it is necessary to remove it to 
 permit of the plaster impression being nearly all cut away before 
 the model is mounted on the articulator. 
 
 The face-bow is used in exactly the same manner as in taking a 
 wax bite for. a plate. The index rods are adjusted to the external ends 
 of the condyles and the stem of the plate, which is imbedded in 
 the plaster, is fastened in the clamping device and the whole 
 retained in place until the plaster has thoroughly hardened, when 
 the impression with the bow attached is removed from the mouth. 
 
 It will be remembered that after imbedding the disk in the impres- 
 sion, the plaster has been scraped partially away from the upper 
 surface for the purpose of weakening it so that the disk can easily 
 be removed. This is done by holding the impression m one hand 
 and grasping the stem in the other and lifting it until it breaks 
 away, care being used not to disarrange the adjustment of the stem 
 in the bow. 
 
 The caps and bands are now removed from the mouth and care- 
 fully placed in the impression and waxed in place, in the manner 
 already described, and the impression varnished. After varnishing 
 it is well dusted with talcum powder and the surplus powder is 
 blown out with the chip-blower so as to render the separating 
 easier. 
 
 The lower half of the model is cast first and the surplus plaster 
 placed on a slab. The model is then placed on the plaster and 
 leveled very carefully. After this has hardened, the upper side is 
 cast and this is also inverted and placed on the surplus plaster on the 
 slab, leveling it so that this side is parallel with the lower half. In 
 casting both the upper and the lower, care must be used not to get 
 any plaster at the point where the plate, from the face-bow, has 
 been broken away. 
 
 After the model has thoroughly hardened, the bulk of the impres- 
 sion is carefully cut away, simply leaving a few points of contact 
 to hold the halves in position and also preserving the surfaces where 
 the semicircular plate has been attached. The plate is then carefully 
 fitted in its proper position and waxed firmly in place. The bow 
 is attached to the articulator and the models are fastened and 
 built up properly with plaster. The face-bow is now removed 
 
ARTICULATORS 
 
 135 
 
 from the articulator and the remainder of the impression is cut 
 away, thus releasing the halves and giving a perfectly occluding 
 working model. 
 
 In making a full denture, it is more necessary, than in small 
 cases, that the articulator which is used should be one which will 
 give all the natural movements of the mandible. The Gritman 
 or Snow articulator is recommended, being simple and easy of 
 manipulation (Fig. 158). 
 
 If the face-bow has not been used, the model is prepared in the 
 same way, casting the lower half first and leveling it very carefully 
 on the surplus plaster on the slab, sa that the occlusal plane will 
 be as nearly correct as it is possible to make it. The upper half 
 is then cast in the same manner and made so that the upper and 
 lower surfaces are perfecth' parallel. 
 
 Fig. 158 
 
 After the model has thoroughly hardened, the impression is cut 
 away, leaving only three or four points of contact to retain the 
 parts in their normal position. In such cases, the anterior part 
 should be well exposed, and also the buccal sides of the molars 
 on each side of the model, so that the position of the median line 
 can be determined. The exposed parts will serve as a guide in 
 mounting it on the articulator, after which the remaining parts of 
 the impression can be cut away. 
 
 Making a Plaster Articulation. — It is always best to follow some 
 fixed rule in making small models from a "squash" plaster impres- 
 sion and bite. In fact, to follow some fixed rule of procedure in 
 all of our operations will be time-saving. The lower half of the 
 model is always cast first, irrespectiv^e of which jaw the bridge is 
 being made for. The object of this is as follows: 
 
136 
 
 IMPRESSIONS AND MODELS 
 
 A very large proportion of bridges made are those which restore 
 teeth which have been lost from either side of the mouth, extending 
 from the bicuspids to the molars. The models for these cases will often 
 be made on nearly a straight line, their shape giving no clue as to which 
 side of the mouth they belong. After the two halves have been cast, 
 the next step, after removing it from the slab, will be to cut away 
 the surplus plaster, and do a portion of the trimming before separat- 
 ing. If the rule of casting the lower half of the model first has been 
 followed, as soon as the distal portion of the model has been trimmed 
 
 Fig. 159 
 
 sufficiently to show upon which half the grooves were cut, it can be 
 told at a glance which is the upper and which is the lower half. 
 (Fig. 159). This enables the operator to tell very nearly where the 
 abutments are located, and knowing this, the impression can be cut 
 away more quickly and certainly than if the models were made in 
 a haphazard way. In the latter case, the operator would have to 
 work much more slowly, carefully cutting into the impression until 
 a part of the model was exposed, before determining which was the 
 upper and which was the lower, thus losing many minutes of valu- 
 able time. 
 
 CASTING OF PLASTER MODELS. 
 
 The models should always be well made and neatly prepared, 
 and should also be of a size corresponding to that of the work 
 which is to be done upon them. 
 
CASTING OF PLASTER MODELS 
 
 137 
 
 A piece of work should never be undertaken on an irregular and 
 ungainly mass of plaster, called a model. The models should be 
 carved and finished neatly. It is an old saying that a good workman 
 can do good work with poor tools and instruments, but there is no 
 question but that he could do much better work if he had better 
 toojs and instruments with which to do it with, and so can a man 
 do much better work on a model which is well 
 and neatly prepared than it is possible to do 
 on one which is poorly made. 
 
 As previously stated, the model plaster 
 should set very hard and is coarser than the 
 impression plaster. The difference between 
 the two can be readily distinguished by simply 
 rubbing it between the fingers, the impression 
 plaster being fine and smooth like flour, while 
 the model plaster will feel coarse and rough in 
 comparison. In mixing the plaster, cold water 
 is used and nothing should be added to hasten the setting as this 
 will tend to make a softer model. It should be stirred very lightly, 
 as much stirring has a tendency to hasten the setting of the plaster, 
 thus making it softer. The water is first put in the bowl and then 
 the plaster carefully sifted from the knife or spatula around the 
 edges of the bowl, allowing it to work toward the center. The 
 
 Fig. 160 
 
 Fig. 161 
 
 plaster is slowly added until all the moisture is taken up so that it 
 will be a fairly stiff mass. The plaster should never be so soft that 
 it can be poured into the impressions. It is well to remember that 
 the stiffer the plaster is mixed, the harder will be the model. It 
 should be stirred just enough to thoroughly incorporate the plaster 
 and follow this by cutting through the mass, with the spatula edge- 
 wise, to work out any air bubbles which may be there. 
 
138 
 
 IMPRESSIONS AND MODELS 
 
 The impression previously coated with separating solution and 
 dusted with talcum powder, is dipped in water and the water lightly 
 shaken out, leaving very little in the deeper parts. A small portion 
 of the plaster is then placed on the sides of the impression and 
 worked down into the deeper parts by jarring it 
 with the hand (Fig. 160), adding a little at a time, 
 and working it down gradually, so that no air 
 bubbles are enclosed in the mass. This is con- 
 tinued until the impression is filled. The excess 
 of plaster is then placed on a glass slab and the 
 impression inverted and pressed into it. The 
 excess plaster should extend about one and one- 
 half inches back of the impression (Fig. 161). 
 This can then be smoothed off and grooves cut 
 into it to the depth of a little less than one-eighth 
 of an inch, say about three thirty-seconds, one 
 groove being cut at right angles to the mass, and 
 the other parallel with the sides and in the center 
 of the extension (Fig. 161). 
 
 A simpler and quicker method is to use the 
 little articulating plates designed by the writer, 
 and which can be purchased at any of the dental depots (Fig. 162). 
 They were carefully designed and much study was given to the 
 depth of the grooves which they would make in the plaster. The 
 grooves are made so that with the lateral movement, the model 
 
 Fig. 162 
 
 Fig. 163 
 
 will be raised and lowered to about the same degree as the cusps 
 would give to the same movement in the mouth. If the grooves 
 are made too deep, in moving the model in any direction, the 
 articulator would be opened too wide, and if they are too shallow 
 the movement would not be sufficient. 
 These articulating plates are used as follows: The excess of 
 
CASTING OF PLASTER MODELS 
 
 139 
 
 plaster is extended backward from the impression about one and 
 one-half inches. The lower side of the plate is moistened and 
 covered with soft plaster and is then pressed into the surplus extend- 
 ing back of the impression, so as to come even with the occlusal 
 surfaces of the teeth (Fig. 163). The excess of plaster is trimmed 
 away from the impression and flush with the edges of the plate 
 and the model left until the plate will come away by simply touching 
 it lightly on the under side of the extending handle. This will 
 
 Fig. 164 
 
 Fic. 165 
 
 generally be in from five to eight minutes after the model has 
 been cast. It is not well to undertake to remove the plate forcil)Iy 
 before the plaster has hardened, as if this is done the plaster will 
 adhere to it and will roughen the articulating surface. 
 
 After the plate has been removed, the grooves will be in the right 
 position and of i)roi)er depth. The model is loosened from the slab 
 by holding the slab over the Bunsen flame for an instant. The 
 
140 ~ IMPRESSIONS AND MODELS 
 
 model is trimmed, the sides smoothed and the articulating surface 
 varnished with the colored sandarac. 
 
 The second or upper half is now cast in exactly the same way, 
 wetting it and then jarring the plaster in, a little at a time, until 
 the impression is filled and the plaster carried back to about the 
 same depth over the articulating surface. 
 
 The excess plaster is then put on the slab as before and the piece 
 inverted and pressed into it, keeping both sides parallel. After 
 it has become sufiiciently hard to remove it from the slab, it can 
 be trimmed and smoothed, preparatory to separating. 
 
 In making the articulation, the model should be made to articu- 
 late so that the movements will be exactly the same as in the mouth. 
 If the crown or bridge is on the side of the mouth, the articulation 
 should be carried directly back from the molars following the line 
 of the arch (Fig. 164). If it is in the anterior part of the mouth, it 
 should be directly back of and in line with the median line and the 
 center of the palate (Fig. 165). 
 
 SEPARATING THE IMPRESSION FROM THE MODEL. 
 
 When the plaster for the impression has been tinted, the impres- 
 sion and model are easily distinguished by the difference in coloring. 
 It can readily be seen, from having run the lower half first, on which 
 half of the model the bridge is to be made, and knowing that the 
 occlusal surfaces of teeth are on a line with the articulating surfaces 
 of the model, it is possible to determine very nearly where the abut- 
 ments are located. The impression is rapidly cut away over these 
 abutments until they are exposed, and they will serve as a guide for 
 removing the remainder of the impression. This should be done very 
 carefully and after it has been removed, the separation of the bal- 
 ance can very easily be completed by working them slightly from side 
 to side or introducing the point of the knife between the forward 
 end of the articulating surface and rotating it a little. The model 
 is then trimmed and carved as may be desired. 
 
 Preparing Working Models. — In making a bridge for the back of 
 the mouth, where the abutments are to be shell or telescope crowns, 
 if, the teeth are properly prepared, the entire work of making the 
 bands and completing the bridge can be done on the model. There 
 will be no necessity for seeing the patient after we have taken 
 the impression and bite, and we can be sure that the bridge, when 
 completed, will go in place as it should. 
 
SEPARATIXG THE IMPRESSION FROM THE MODEL 141 
 
 When the work is to be done entirely on the model, the teeth 
 must be carefully and accurately trimmed, and not only should the 
 abutments be parallel, but there must be no ledges below the gum 
 line which will interfere with the placing of the bands in position. 
 
 Extreme accuracy in the preparation of the abutments, so that 
 the sides will be only slightly larger beneath the gum line and 
 practically free from ledges, will come only with practice, and bv 
 using great care in the work. The knowledge that if this perfect 
 preparation is accomplished, all of the work can be performed out 
 of the mouth, will serve as an incentive for the operator to put 
 forth his best efforts. 
 
 It is always advisable to do as much of the work as possible on 
 the model and only such as may be necessary in the mouth, as the 
 moral effect on the patient is something to be desired. It does 
 not make any difference how skillful the operator may be, his best 
 efforts will, at times, seem clumsy to the patient. They do not 
 always realize the care and accuracy which is absolutely essential 
 in fitting the band. The constant taking off, trimming and replac- 
 ing the bands on the teeth is necessarily painful, and may often 
 suggest to them that if the operator was as skillful as they had 
 supposed, he should be able to do the work more quickly, and with 
 less pain. On the other hand, if, after the impression has been 
 taken, they are not required to call again until after the bridge is 
 completed, it will seem to them marvelous that such beautiful work 
 could be produced from an impression that appeared to them to be 
 but a few worthless bits of broken plaster, and they will immedi- 
 ately be inspired with a much higher opinion of the skill 
 and abilities of their dentist. 
 
 After the models have been separated and carved, they 
 should be thoroughly dried with a gentle heat. If they 
 are dried rapidly, the plaster will become baked, with the 
 result that it will be soft and chalky, easily crum})Ie(l 
 between the fingers, and worthless as a model. In cold 
 weather, by placing the models in front of a register or 
 over a radiator, the proper amount of heat to dry them 
 slowly and render the models hard will be obtained. '° 
 
 After the models are thoroughly dried out, they should 
 be <-arcfully trimmed. This is best done with a fairly 'gogg '~ 
 bn^ad hoe-shaped excavator (Fig. KUi), with the edges of 
 the inner sides of the instrument slightly rounded so that it will 
 not scrape the sides of the abutments. The plaster is carefully cut 
 
142 
 
 IMPRESSIONS AND MODELS 
 
 away to about one-sixteenth of an inch beneath the gum Hue, using 
 great care to cut to the same depth all around, and also, not to 
 scrape the sides of the stumps so as to change their size and shape, 
 otherwise bands which are fitted to the model will not fit the teeth 
 in the mouth (Fig. 167). 
 
 After the stumps have been carefully trimmed, the models should 
 be thoroughly saturated with dilute sandarac varnish. This can 
 be done by using a brush and painting them repeatedly with the 
 solution, giving them one coating after another 
 as long as the varnish will soak into the plaster, 
 or until it begins to glaze. If the models are not 
 too large, they may be placed in a large jar of 
 the varnish and left in it until they have taken 
 up all that they will. The varnish should be 
 thin so that it will soak well into the plaster. 
 The sandarac varnish as procured at the dental 
 depots, diluted from one-half to three-quarters with alcohol, will 
 be of about the right consistency. 
 
 The models are now again dried out thoroughly with a gentle 
 heat, and it will be found that the surfaces are extremely hard. 
 By using care, a number of pieces might be made on the same 
 model, with but little or no abrasion of the stumps. 
 
 There are other ways of hardening models. A favorite one is, 
 after they have been carefully prepared and thoroughly dried, 
 to boil them in sterine or paraffin. This makes a beautiful model, 
 but one not as good to work on as those which have been treated 
 with sandarac varnish. The varnish makes them much harder 
 and gives them a better wearing surface. 
 
 Fig. 167 
 
CHAPTER VIII. 
 
 BUILDING UP BROKEN-DOWN ROOTS WITH AMALGAM 
 PREPARATORY TO CROWNING. 
 
 The building up of roots with amalgam, preparatory to crowning, 
 is a very questionable proceeding. Every dentist knows, or should 
 know, that gold antl mercury have a great affinity for each other. 
 It is this known affinity of the metals which is taken advantage 
 of in the treatment of gold by the amalgamation process. If the 
 mercury could be entirely removed from the amalgam of course 
 there would be no objection to its use, but this cannot be done and 
 if it could, it would no longer be an amalgam. 
 
 The gold crown, coming in contact with the amalgam, is attacked 
 by the mercury and disintegrated. Many times, even where gold 
 bands come in contact with old amalgam fillings which have been 
 
 Fig. 168 Fig. 169 
 
 in the mouth for years, the effect will be the same. The writer 
 has seen many instances of this kind, where a tooth having amalgam 
 filling has been covered with a gold crown, the band coming in con- 
 tact with the filling, with the result that within a year or two the 
 entire side of the cnnvn has been disintegrated and broken away. 
 Of course, if the band be made of crown metal, or of platinum, the 
 eff'ec-t would not be so marked, but the platinum caps, in connection 
 with the bridge, arc undesirable and unsightly. 
 
 Another objection to tiiis method, ignoring entirely the remark- 
 able affinit>- which gold and mercury have for each other, is that 
 from a practical staiid|)oint, in the majority of cases, in a root so 
 built \\]> with amalgam, the amalgam stump is in reality an element 
 of weakness rather than of strength. 
 
 (143) 
 
144 BUILDING UP BROKEN-DOWN ROOTS 
 
 We will take, for example, a molar which is broken or decayed 
 well below the gum line. The general practice, in building up these 
 roots, is to put pins in the canals and then build the stump above 
 the gum, trimming the amalgam flush with the sides of the stump 
 (Fig. 168). The band is fitted to the amalgam stump, the crown 
 made and the bridge connected to it (Fig. 169). 
 
 In masticating, the lateral strain on this stump is very great 
 and the tendency is for the amalgam to pull away from the face of 
 the root labially and lingually, allowing moisture to work in, with 
 the result that the tooth or stump will decay, eventually resulting 
 in its entire destruction. We say that there is a tendency for this 
 to happen, but there is more than a tendency . There is an absolute 
 certainty that this will occur sooner or later. There is also a lia- 
 bility of the root becoming fractured from the extra strain which 
 is thus placed upon it. 
 
 CROWNING BROKEN-DOWN ROOTS. 
 
 When a tooth is broken or decayed below the gum line, the band 
 should always be carried below the line of fracture or decay in 
 order that the root may be perfectly protected. 
 
 In a majority of cases of this kind, it is practically impossible to fit 
 the band in the mouth or indeed, even to get a correct measurement 
 of the root. Even if it were possible to do so, it could be done only 
 at the expense of excruciating pain to the patient. In all cases of 
 this class, the band should be made and fitted to a carefully prepared 
 model. 
 
 Taking Impression and Preparing Models for Broken-down Teeth 
 or Roots. — We will consider first a very common example of this 
 class. An upper first or second bicuspid. The roots of these teeth 
 are often found decayed far below the gum line. Sometimes, on 
 the mesial and distal sides, below the process, while on the buccal 
 and lingual sides they may be decayed beneath the gum, but not 
 to the same depth as mesially and distally (Fig. 170). It can be 
 readily seen that a root in this condition, cannot be treated in the 
 same manner as one which is standing out of the gum, and the 
 only method which can possibly be followed with accuracy and a 
 minimum amount of pain to the patient is to first secure an accurate 
 impression of the face of the root and then prepare a model on 
 which to fit the band. 
 
 Usually the gum tissue has. grown over the stump. This must 
 first be removed, either by cutting it away with gum scissors or a 
 
CROWNING BROKEN-DOWN ROOTS 
 
 145 
 
 lancet, or by using trichloracetic acid or some other powerful 
 escharotic. After this has been done, it is better, in order to still 
 further free the root-end from the gum tissue, to pack it tightly 
 with gutta-percha or cotton, and let it remain for a day or two, so 
 that when the work is commenced, the face of the root may be per- 
 fectly free from all intruding tissue. 
 
 It is rarely that there is much trimming to be done on such 
 roots, as the decay has generally passed beyond the line of enamel 
 to a point where the sides of the root are nearly parallel. The 
 little trimming may be necessary should be carefully done, and 
 with very sharp instruments. 
 
 Fig. 170 
 
 Fig. 171 
 
 Fig. 172 
 
 Fig. 173 
 
 In such a case it is plainly impossible to get an accurate impres- 
 sion with plaster. A material must be used which will force the 
 soft tissues away from around its margin'^, and at the same time 
 give a clear outline of the root. A fairly hard and tough wax is 
 indicated. The writer has for many years used pink paraffin and 
 wax for this purpose. This wax is moulded in the form of a cone, 
 of about the size and shape shown (Fig. 171). 
 
 Plaster-of-Paris moulds may readily be made, in which to cast 
 these cones, and it is well to prepare a number, and keep them on 
 hand for use as needed. The cones are used nearly full hard, being 
 warmed slightly by holding in the hand for a moment before 
 using. The point of the cone is then placed in the center of the 
 root (Fig. 172), holding it in place with the thumb. Pressure is 
 gradually applied and as the cone softens slightly from the heat 
 of the mouth, the wax is spread out over the stump, and the tissues 
 are forced away from around the margin of the root (Fig. 173). 
 This is necessarily somewhat painful, but it does not last long, 
 and the patient never objects. After it has been jjressed up as 
 far as necessary, it is removed. By this means a clear sharp impres- 
 10 
 
146 
 
 BUILDING UP BROKEN-DOWN ROOTS 
 
 sion of the outline of the root can be obtained, even though it be 
 decayed far below the alveolar border (Fig. 174). The model is 
 now made from this impression. 
 
 Preparing the Models. — ^The model can be made of oxyphosphate 
 of zinc if so desired, but one made of hard plaster will answer 
 every purpose. The plaster is mixed very thick, the impression 
 is moistened, a little of the plaster placed on it and jarred carefully 
 in place. This must be done carefully, so as to make sure that the 
 fine lines will be reproduced. After the plaster has well hardened, 
 the impression is separated from it and the model is thoroughly 
 dried out. It is then trimmed, great care being used not to break 
 the thin edges, representing the thin edges of the root, while follow- 
 ing the outline, and cutting parallel with the sides of the root to 
 
 Fig. 174 
 
 Fig. 175 
 
 Fig. 176 
 
 Fig. 177 
 
 Fig. 178 
 
 about one-sixteenth of an inch below the line of decay (Fig. 175). 
 It is then soaked in thin sandarac varnish and again thoroughly 
 dried. The decay having eaten deeply into the center of the tooth, 
 the edges of the stump are very frail (Fig. 176). To lessen the 
 liability of their breaking while fitting the band, the cavity may 
 be filled with hard wax flush with the edges of the stump. 
 
 The measurement can now be taken and the band made, fitting 
 it in closely at the constriction between the two roots, and trimming 
 it so that it will exactly follow the outline of the cavity (Fi^. 177). 
 The edges are then beveled from the outside, leaving a keen 
 knife-edge on the inside of the band, and it is ready for the mouth 
 (Fig. 178). 
 
 The gum around the stump is then cocainized, and the band 
 forced into place, the sharp edges being driven between the root 
 and the process, thus gripping the root firmly. 
 
 After the band is in position on the root, the canals can be opened 
 and treated, the band, being firmly fixed, will keep away the soft 
 tissues, blood and moisture. When the band is removed, the 
 stump should be tightly covered with hard gutta-percha to keep 
 
CROWNING BROKEN-DOWN ROOTS. 
 
 u: 
 
 the gum from crowding over the face of the root. An ordinary 
 large-headed tack is good for this purpose, covering the post well 
 with the gutta-percha and forcing it into the canal, the excess 
 gutta-percha being forced over the face of the root by the head of 
 the tack. The head can then be covered lightly with gutta-percha 
 and it will keep in position for any desired length of time. 
 
 It is more than twenty years since the writer first employed this 
 method of crowning such like roots. It was feared that forcing 
 the band between the root and the process might cause resorption, 
 but he considered the experiment was well worth trying and he 
 has not since regretted it. Since that time, this has always been his 
 method of procedure in these cases, and so far as is known there 
 has not been a single failure. This method may be employed in 
 nearly all cases where the tooth has been broken or decayed below 
 the gum line. 
 
 Fig. 179 
 
 Fig. 180 
 
 Another class of cases, which is frequently encountered, is where 
 a large cavity in a molar extends far up on the root beyond the 
 gum margin, as in Fig. 179. The gum should be first cleared from 
 the cavity. This can be done by lancing, or if there is not very 
 much soft tissue in the cavity, trichloracetic acid may be used. 
 Frequently, the impaction of food has kept the cavity partially 
 clear of soft tissues, and it may be possible to force out any 
 remaining tissue by packing gutta-percha or cotton tightly into 
 the cavity, and leaving it there until a subsequent sitting. 
 
 The decay is first entirely removed, and the cavity prepared so 
 that it is non-retentive in shape (Fig. 180). If there are any 
 undercuts, they may be temporarily filled with gutta-percha. 
 The remaining sides of the tooth are trimmed so that they are 
 nearl\' parallel, the same as though preparing the entire tooth 
 for a crown. The cavit\' is then filled with a slow-setting cement, 
 and this is carefully trimmed, following closely the sides of the 
 
148 
 
 BUILDING UP BROKEN-DOWN ROOTS 
 
 root, making sure that the cement does not project in the least, 
 beyond the margins of the cavity, and making the filhng nearly 
 parallel with that part of the tooth which remains standing. It 
 should be notched or grooved slightly on the top (Fig. 181). 
 
 An impression of the stump is now taken with the cement filling 
 in position. After the impression has hardened, it is removed 
 from the mouth (Fig. 182), and the cement filling (Fig. 183) 
 
 ///A/^y 
 
 Fig. 181 
 
 Fig. 183 
 
 removed from the tooth and placed in position in the impression, 
 and waxed lightly, as in Fig. 184. The tooth cavity should be 
 packed with gutta-percha so as to keep it open and the margins 
 clear. 
 
 The impression is now varnished and a model of hard plaster 
 made from it in the usual manner (Fig. 185). After drying out 
 thoroughly, the model is trimmed to about one-sixteenth of an inch 
 
 Fig. 184 
 
 Fig. 185 
 
 below the gum line, cutting the plaster away from around the 
 cement filling to about the same depth, thus exposing it and showing 
 the exact outline of the cavity (Fig. 186). 
 
 The measurement of the stump should be taken just below 
 the gum line. The band is made, and the gingival end trimmed 
 carefully, so that it follows the outline of the cavity and covers well 
 the line of decay (Fig. 187). The edges are then beveled. It is 
 then tried in the mouth, fitted over the stump, and driven into 
 
CROWNING BROKEN-DOWN ROOTS 
 
 140 
 
 place. The impression and articulation is then taken, the model 
 prepared and the crown completed (Fig. 188), and after completion, 
 is cemented in the mouth. It will be found to cover the margins 
 and fit the root more perfectly than would have been possible to 
 make it fit in any other way (Fig. 189). 
 
 Anterior teeth, such as the centrals or laterals, are frequently 
 found, which have been broken off as from a blow, the fracture on 
 
 Fig. 187 
 
 Fig. 188 
 
 Fig. 189 
 
 the lingual side extending far below the gum line (Fig. 190). They 
 should be treated in practically the same way as the molars in the 
 preceding case. The stump standing out of the gum is trimmed 
 very carefully so that the sides are parallel. In this case, much 
 greater care should be exercised to have these sides parallel than 
 where the whole stump is standing and the root has simply to be 
 crowned. The canal is enlarged and a post fitted into it, extending 
 well out of the stump. 
 
 Fig. 190 
 
 Fig. 191 
 
 Fig. 192 
 
 It is understood that the tissues should be first i)ressed away 
 (Fig. 191). The fractured part is then built up with cement to 
 about the same height as the part of the stump left standing out 
 of the gum, care being taken to trim close to the margin of the 
 root and make the sides of the cement filHng parallel to the stand- 
 ing stump (Fig. 192). 
 
 1 f ue have the part of the root which has been broken of}', it can be 
 \)\\t back in j)osition after removing any of the enamel which may 
 
150 
 
 BUILDING UP BROKEN-DOWN ROOTS 
 
 adhere to it, instead of replacing it with cement. The impression is 
 taken with this in place, the same as with the molar. The broken 
 piece of the root or the cement is then removed together with the 
 post, and placed in the impression, and a model made in the man- 
 ner already described in treating of the molar. The model is then 
 trimmed, carefully, well below the gum margin labially, and below 
 the line of fracture lingually (Fig. 193). The cement and post are 
 
 Fig. 193 
 
 Fig. 194 
 
 Fig. 195 
 
 now removed and the labial side of the stump cut off enough so 
 that the band will be hidden by the gum (Fig. 194). On this model 
 the band is fitted, festooning it carefully so that it will come below 
 the line of fracture lingually, and well under the gum on the labial 
 side (Fig. 195). 
 
 If, for this case, a Richmond crown, with a facing and a gold 
 back, or an all porcelain crown with a soldered or a cast base, 
 is to be made, the upper edge of the band may be cut flush with 
 
 Fig. 196 
 
 Fig. 197 
 
 Fig. 198 
 
 the edges of the stump lingually, and well under the gum labially 
 and a floor soldered or sweated to it. The post is next fitted and 
 waxed in position and soldered to the floor of the cap (Fig. 195). 
 This completed cap is then placed on the root in the mouth, an 
 impression and articulation taken, the model prepared and the 
 crown made and finished in the usual manner, carrying the solder 
 down to the edge of the band on the lingual side (Fig. 196). 
 Where it is intended to use a facing, building up the lingual 
 
RELATION OF PROSTHODONTI A AND ORTHODONTIA 151 
 
 side with porcelain, the band and floor are made of iridio-phitinum. 
 The band on the hngual side should extend at least one-thirty- 
 second of an inch above the line of fracture (Fig. 197). On this 
 side a floor should be fitted to the inside of the band over the 
 broken face of the root, allowing the band to extend above it, 
 but on the labial side it can be brought over the top of the band 
 and well under the gum. The band extending above the floor of 
 the cap on the lingual side forms a protected seat in which porce- 
 lain is baked so that there will be no thin margins of porcelain 
 which would be liable to crack and flake off (Fig. 198). 
 
 PORCELAIN. BRIDGES. 
 
 The porcelain bridge as advocated by many dentists some years 
 ago has become nearly obsolete. Porcelain is a fragile material, 
 it cannot be made sufficiently strong to withstand the force of 
 mastication without great depth and bulk of porcelain, as the 
 strength of porcelain is only in proportion to its bulk. 
 
 Where the posterior teeth have been lost it is, in the majority 
 of cases, necessary to open the bite. By doing this the masticatory 
 force is greatly increased, and there is no porcelain made which 
 will withstand the strain, unless, as before stated, the bridge is 
 made with great depth and bulk of porcelain, or the patient is 
 wearing a plate in the opposite jaw. 
 
 Taken purely from an esthetic point of view% porcelain is the 
 ideal material to use, but from a practical standpoint, it is not so 
 ideal. A porcelain bridge would stand better if it were a fixed 
 bridge than it would if it w^re removable, as the springing which 
 occurs in removing and replacing the appliance will, in every 
 case, sooner or later, cause a checking of the body, necessitating 
 constant repairs. 
 
 RELATION OF PROSTHODONTIA AND ORTHODONTIA. 
 
 Quite frequently when the services of an orthodontist has been 
 emi>loyed the cooperation of the prothodontist is necessary to 
 complete and render his work permanent. Where the teeth have 
 been regulated in mouths where some of the teeth have been lost, 
 it is necessary to restore these lost organs by some rigid fixture, 
 otherwise the teeth which have been put in proper occlusion will 
 quickly /eturn to their former condition. Where such conditions 
 
152 BUILDING UP BROKEN-DOWN ROOTS 
 
 exist, there is no appliance so far suggested as satisfactory and 
 efficient as a properly constructed bridge. 
 
 In a large number of these cases the patient is too young to have 
 any permanent appliance made which would necessitate the devi- 
 talization of a tooth. Where this is so a temporary bridge can be 
 made, the abutment teeth being trimmed only just enough to allow 
 of the passing of the band between them and the adjoining teeth, 
 but not cutting through the enamel. 
 
 The bridge can then be made and cemented into position, and 
 should be carefully watched until the patient is old enough to have 
 a permanent fixture made. Generally this is not advisable until 
 the patient has reached the age of at least eighteen years. 
 
 There are many cases where slight irregularities of the teeth 
 brought about by the loss or decay of others can be, previous to 
 crowning, easily and quickly corrected without employing the 
 services of an orthodontist.^ 
 
 Fig. 199 Fig. 200 
 
 An example of this would be where a tooth, say a lateral incisor 
 may be standing a little distance inside of the arch (Fig. 199). It 
 has been the custom with some dentists to cut off such a tooth, 
 making a cap for it and letting the floor extend over the ridge to a 
 point in line with the labial face of the adjoining teeth. The facing 
 is then ground in position, backed and soldered, with the backing 
 carried lingually, and over the root cap, so as to bring the facing 
 into proper position, as in Fig. 200. This is not good practice if it 
 can possibly be avoided, as it makes a weak and uncleanly appliance. 
 
 It is better that this root or tooth should be brought out in line 
 with the other teeth before attempting to crown it. This can often 
 be done in a few days with some little simple mechanical appliance. 
 
 One of the simplest appliances for this purpose would be a piece 
 
 ' The writer is not posing as an orthodontist and does not intend to give any 
 advice as to the regulating of teeth except in cases where the irregularities are so 
 slight that they may be corrected in a few days. 
 
RELATION OF PROSTHODONTIA AND ORTHODONTIA 153 
 
 of spring wire attached to the adjoining cuspid and extending over a 
 few of the teeth adjoining. To this the lateral can be attached 
 with a ligature and by tightening it frequently the teeth can be 
 brought in line very quickly. If the crown is lost a staple or 
 hook can be placed in the root and the ligature attached to 
 that. 
 
 Another appliance, which can be quickly and easily constructed 
 and which gives a more positive pressure than does the spring wire, 
 is made in two parts. The first consists of a platinized gold bar, 
 heavy enough to resist the strain and long enough so that the ends 
 will rest on the adjoining teeth. A hole is drilled through at a point 
 opposite the lateral which is to be moved. The second part is a 
 small round rod of the same metal, one end of which is shaped so 
 as to form a hook and the other end having a thread cut on it to 
 which a nut has been fitted. 
 
 The rod is hooked to the staple or other fixture in the lateral, 
 the other end passed through the hole in the bar and the nut screwed 
 on. By tightening this nut frequently, the tooth or root is quickly 
 and easily brought in line (Fig. 201). 
 
 In cases where the space for a lateral or a central incisor is nearly 
 closed, and it is necessary to move a number of the teeth in order 
 to make room, it may be advisable to employ the services of an 
 orthodontist. 
 
 Fig. 201 Fig. 202 
 
 Another class of cases of slight irregularities which are very 
 frequently encountered is where the crowns of certain teeth are 
 lost and the adjoining teeth have moved together, so as to partially 
 close the space and there is not enough room to insert a crown of 
 normal size. In fact, quite often the space may be narrower than 
 the width of the broken-down root. This is frequently seen where 
 the crown of a first or second bicusi)id is lost, and the adjoining 
 bicuspid anfl molar has moved forward so as to partially close the 
 space as in Fig. 202. 
 
 It would be bufl prac-ticc to place a crown on a root, where these 
 
154 BUILDING UP BROKEN-DOWN ROOTS 
 
 conditions exist, without first forcing them apart so as to get room 
 enough in which to place a crown of normal size. This can be 
 done easily and quickly, in the majority of cases, even when none 
 of the molars are missing, without making any mechanical appliance 
 at all, but simply by wedging. 
 
 If the three molars are standing, and the second bicuspid missing, 
 the first step would be to put a blocking of wedges tightly between 
 the molar and the first bicuspid, so that the molars could not move 
 forward. Then begin by making a separation between the second 
 and third molars, starting at first with as large a piece of separating- 
 rubber as can be placed between these teeth. After they have been 
 forced apart, somewhat, the work of separating may be completed 
 with orangewood wedges. The space between is dried out and a 
 piece of well compressed orangewood is driven in between the 
 teeth as tightly as possible. As the wood becomes moistened, it 
 expands and forces the teeth still further apart. This is repeated 
 until the amount of separation between the second and third molars, 
 added to that of the space of the first molar and first bicuspid 
 will give sufficient space for a crown of normal size. 
 
 The next step is to start wedging between the first and second 
 molars, at the same time easing up, as progress is made, the separa- 
 tion between the second and third molars, wedging with the orange- 
 wood until the second molar has been forced back against the 
 third. 
 
 Fig. 20.3 
 
 There now remains only the one tooth to be moved to its normal 
 position, the first molar. This is moved in the same manner as the 
 others, by increasing the size of the wedges between the first bi- 
 cuspid and first molar, and decreasing those between the first and 
 second molars, and keeping this up until a little more space than 
 is necessary for a normal sized crown has been secured, (Fig. 203). 
 The space should be carefully preserved with wedges until the 
 root is prepared and the crown made, and in place, otherwise 
 the molars would quickly resume their former positions. 
 
nELATIOX OF PROSTHODONTTA AND ORTHODONTIA 155 
 
 It has been claimed that the third molars cannot be forced back 
 but with this the writer cannot agree, as it has been done many 
 times, in the manner stated. 
 
 There are many cases Where the work of securing a separation 
 can be done entirely by the patient, especially if the third molar 
 or second and third have been lost. The first step is to cut an 
 orangewood stick of such a length that it will wedge in tightly 
 between the bicuspid and the molar, concaving it a little at each end 
 so that it cannot be forced out bucally or lingually. A number of 
 these orangewood plugs are prepared, each one a little longer than 
 the others, the last one being slightly longer than the space which 
 is needed for the crown (Fig. 204). They are numbered 1 , 2, 3, etc., 
 beginning with the shortest which is numbered 1. The Xo. 1 plug 
 is now forced into position between the bicuspid and the molar 
 (Fig. 205). The others are placed in an envelope on which instruc- 
 
 FiG. 204 Fig. 20.5 
 
 tions are written, and given to the patient, the instructions stating 
 that as soon as the wedge which is in the mouth has become loosened 
 somewhat, so that it can be moved easily, the No. 2 is put in position 
 and bitten into place. This is repeated as soon as the No. 2 is loose, 
 the No. 3 is forced in place and so on until the last one is in. The 
 patient is instructed to return after the last plug has been in place 
 for three or four days. 
 
 It will be found that in the majority of cases the teeth can be 
 moved for a considerable distance in ten days or two weeks with 
 practically no pain to the patient. As the teeth are forced apart 
 they are held perfectly rigid, so that there is no movement which 
 will keep up an irritation. 
 
 The same method of gaining space may be adopted in the anterior 
 part of the mouth. Many times, where the crown of a tooth has 
 been broken away, say that of a central, or where the central root 
 is missing, the remaining central and lateral will come together 
 
156 
 
 BUILDING UP BROKEN-DOWN ROOTS 
 
 so that perhaps the space between them is less than half the width 
 of the remaining central (Fig. 206). 
 
 In such a case a crown on the root or a bridge restoring the missing 
 tooth should not be placed unless the tooth can be made of a size 
 corresponding very nearly to that of the remaining central. If a 
 narrower crown is placed, one not nearly as large as its mate, it is 
 unsightly, and these teeth should always be separated so as to make 
 room for a tooth of normal size. 
 
 This can usually be done in exactly the same manner as has al- 
 ready been described in speaking of the bicuspid. Sometimes in 
 forcing the teeth apart in this manner there will be a tendency 
 for them to overlap and pass each other. This difficulty can gen- 
 erally be overcome by ligating. 
 
 It not infrequently happens that it will be found that one of 
 these teeth has been loosened, perhaps from a blow, which has 
 
 Fig. 206 
 
 Fig. 207 
 
 destroyed the bony attachment and is holding only by the gum and 
 is laying over the labial side of the adjoining teeth. The remaining 
 central and lateral will have closed in behind it. For esthetic reasons 
 the patient may not wish to have the injured tooth removed with- 
 out having something which can be used temporarily while the 
 permanent fixture is being made restoring a central of a size corre- 
 sponding to the one remaining. 
 
 As an illustration the following description of a case of this kind 
 which came under the care of the writer will serve. 
 
 The patient, a lady over fifty years of age, several years previous 
 had received a blow in the mouth which had loosened the left central 
 incisor. The condition had become worse, until it had only a 
 slight gum attachment and the tooth was practically held in position 
 only by the lip (Fig. 207) . An impression of the parts was taken 
 and a model carefully prepared. The cast of the loose tooth was 
 then cut from the model (Fig. 208) and the model separated by saw- 
 
RELATION OF PROSTHODONTIA AND ORTHODONTIA 157 
 
 ing through between the remaining central and the lateral. The 
 hahes of the model were then forced slightly apart and a tooth, 
 matching the other central in shade, was ground to fit in this space 
 and the outer edges slightly beveled lingually. A thin backing 
 was then fitted to the lingual side of the facing extending beyond 
 it mesially and distally and this extension burnished over the lin- 
 gual side of the adjoining central and lateral (Fig. 209). This was 
 
 Fig. 208 
 
 Fig. 209 
 
 then waxed and invested and covered over with solder. The model 
 was then separated a little farther and another and larger facing 
 ground in place and backed and prepared in the same manner. A 
 third and fourth facing were prepared the same as the others, the 
 last of which was as wide or a little wider than the space required. 
 The teeth with the backings were made in such a way that they 
 would wedge between the central and lateral but could not be 
 forced either labially or lingually (Fig. 210, a and h). 
 
 Vui. 210 
 
 The patient was then sent for, the loose tooth removed and the 
 smaller of the backed facings was forced in between the central 
 and lateral. The i)atient was then given some narrow linen tape 
 and was instructed that as soon as the ap])liance had loosened a 
 little to put a thickness of the tape between the sides of the appliance 
 and the adjoining teeth, and to keep this up until there were three 
 or four thicknesses in place, and then wear it until the piece became 
 slightly loose again. 
 
 In the meantime, the work of devitalizing the adjoining teeth 
 
158 BUILDING UP BROKEN-DOWN ROOTS 
 
 and preparing them for a bridge had been progressing. As soon as 
 the smaller appliance had forced the teeth apart, so that it was loose 
 when worn with several thicknesses of tape, the second appliance 
 was put in and the same directions given regarding the tape. After 
 that had served its purpose the third and then the final appliance 
 was put in position and worn until the permanent fixture was ready 
 to be put in position. 
 
 Tube and inlay attachments were used in this case, and the 
 bridge made to fill the space, the temporary appliances being worn 
 in the meantime, and discarded only when the bridge was ready 
 for the mouth. This made an easy and certain way of getting the 
 needed separation, and during which time the patient was spared 
 the disfigurement which would have been caused by an ordinary 
 separation, and only those intimately acquainted with her knew 
 that there was a tooth missing. 
 
CHAPTER IX. 
 PROSTHESIS. 
 
 AUTOGENOUS SOLDERING, OR THE "SWEATING PROCESS," 
 AND SOLDERING. 
 
 There are two methods in use, where constructing crown and 
 bridge-work, for the making of caps and bands, or uniting pieces of 
 gold of the same carat. First, that of melting or welding the parts 
 together without the use of solder and which is known as the " sweat- 
 ing process," or to use a more scientific term, "autogenous solder- 
 ing." And second, soldering, by the use of alloys a trifle more fusible 
 than the metals to be united, fused between and over the surfaces 
 to be joined, uniting them firmly together. These alloys, termed 
 solders, may be of various grades of fineness, or be of the same grade 
 and yet vary a great deal in point of fusibility. These variations 
 depend upon the kind and quantity of alloy used. As a rule, the 
 higher the carat, or the nearer the fusibility of the solder approaches 
 that of the plate, the stronger will be the union. The higher the 
 fusing point of the solder the less alloy it contains, or the alloy used 
 is, in character, more like the plate. 
 
 Autogenous soldering, or sweating, at its best, makes by far the 
 strongest union. Its chief merit in crown and bridge-work is that it 
 is not re-fused in subsequent solderings. In favorable positions, with 
 a little practice, the art of autogenous soldering is easily acquired, 
 and the union is very satisfactoy. It requires, however, a steady 
 hand, a good blowpipe well managed, and a fair degree of "knowing 
 how," that can be acquired by practice only, to so heat two pieces 
 of metal that the surfaces in contact are fused while the body is 
 near to but not actually at its fusing point. I'nder these conditions 
 there seems to be a molecular attraction between the fused surfaces 
 and they Hcnv together and unite. A little less heat, and the opera- 
 tion is a failure, a little too much, and the appliance is ruined. 
 The real secret of success is in knowing how far to go, and when to 
 .stop. When once the "knack" is acquired, it is surprising how 
 seldom "just right" is missed, and how, as one advances in experi- 
 ence, quickly and with certainty complicated pieces are united 
 
 (159) 
 
160 
 
 PROSTHESIS 
 
 by the sweating method. In fact it is more quickly and easily 
 
 done and with less liability of burning than where solder is used. 
 
 When a band has been joined 
 by this method, there has been 
 a molecular change in the metal 
 so united which renders it 
 somewhat of the nature of cast 
 gold. It has not the same 
 tenacity and strength at that 
 point unless it has been well 
 overlapped. In order to over- 
 come this weakness and bring 
 about a rearrangement of the 
 molecules, the band is placed 
 over the beckhorn of an anvil 
 with the seam uppermost, and 
 the seam is hammered until it 
 is of the same thickness as 
 the rest of the band, and has 
 become entirely obliterated. 
 This forging condenses the 
 gold and restores its tenacity, 
 and makes the band practi- 
 cally seamless, and as strong 
 where it has been joined as at 
 any other point. 
 
 Flattening the seam or 
 stretching a band may be 
 done as well by compressing 
 it between the beaks of a 
 powerful pair of pliers which 
 were designed by the author 
 for this purpose and are known 
 as "stretching and contouring 
 pliers" (Fig. 211). 
 
 Another advantage of the 
 sweating process is that the 
 Pig. 211 seam or joint will not discolor 
 
 after the appliance has been 
 
 worn in the mouth for some time, as does a seam or joint made 
 
 with solder. 
 
AUTOGENOUS SOLDERING, OR SWEATING PROCESS 161 
 
 Another point in favor of the sweating process is that a cap or 
 a crown bnilt up by sohlering and used as an abutment for a bridge, 
 is much more easily burned in any subsequent resoldering opera- 
 tions to which it may be subjected than is a sweated crown. The 
 reason for this is very simple and should be understood by every 
 one doing metal work. 
 
 In using solder, the surface of the gold to which the solder is 
 applied becomes alloyed, the depth to which this alloy extends 
 depending upon the carat, the character, the amount of solder used 
 and also the amount of heat to which the mass has been subjected 
 
 Fig. 212 Fig. 213 
 
 in melting the solder. The carat of the gold has thus been lowered, 
 sometimes to the entire depth of the thickness of the band. The 
 result is, that in such a band, we have already a much lower carat 
 at the point of union than we had at the beginning and far greater 
 care must be exercised in any subsequent solderings with the con- 
 sequent greater danger of burning the band. 
 
 If solder is used for uniting the bands and caps, it should be used 
 in small quantities, and of as high a carat as the gold will stand. 
 
 Fig. 214 Fig. 215 
 
 This can easily be of the same carat as the band, as solder will fuse 
 at a lower temperature than plate of the same carat. Thus, 22 
 carat solder can be used in soldering 22 carat plate.^ 
 
 When j)rcj)ariiig a band for soklering, it is optional whether to 
 unite the ends by an abutted joint, or by lapping them one over the 
 other. An abutted joint is not as strong as one lapped. It is also 
 more difficult to bring the al)utted ends into i)erfect contact and 
 
 ' T\u: carat of K"1<1 dcpond.s upon the quantity of alloy only. The; fusing point 
 ui>on thr; ijuantity and character of the alloy. Any carat may be high fusing or low 
 fiiHing. 
 
 II 
 
162 
 
 PROSTHESIS 
 
 hold them so while uniting them than it is to adjust and hold in 
 contact the ends of a band with a lapped joint. However close an 
 abutted joint may be, the parts are not in actual contact, and after 
 it has been sweated together, it will be really a little thinner at 
 that point, than the band was originally (Fig. 212) thus weakening 
 it somewhat. 
 
 In making a lapped joint there is no necessity for beveling more 
 than one end of the band. The beveled end is brought around 
 and under the end which has not been beveled, sufficiently far to 
 well overlap it, as shown in Fig. 213. Then, the overlapping end is 
 brought back a little, and pressed downward under the other 
 (Fig. 214) so that when it is again restored to its proper position 
 the elasticity of^ the metal wdll hold the two ends in close over- 
 lapping contact. 
 
 Fig. 216 
 
 The joint is then sweated together, melting the overlapping 
 edge well down (Fig. 215). The joint is next hammered on the anvil 
 beak, or flattened with the stretching pliers until the seam on the 
 inside has been entirely obliterated. 
 
 Several different flames may be used in the sweating process, 
 usually, however, after one has mastered the principles involved, 
 the details become a personal matter, and are modified to suit the 
 operation. 
 
 After the ends of the band have been brought into contact and 
 fluxed, it is placed with the lapped edge uppermost on a piece of 
 charcoal. An asbestos block may be used, but it is not as good as 
 the charcoal. Charcoal is cleaner, and reflects the heat, which 
 
CLEANSING GOLD AFTER ANNEALING OR SOLDERING 1G3 
 
 materially aids in the operation. The blowpipe is employed, using 
 a small brush flame until the band is brought to a red heat, almost 
 to the point of fusing. As it begins to glisten, showing that the 
 surface is nearly ready to fuse, the flame is shortened to about 
 from an inch to an inch and a quarter in length and passed slowly 
 along the joint, using the inner point of the blue flame, until it is 
 perfectly united along its whole length (Fig. 216). 
 
 Another method is to sweat the parts together entirely with 
 the brush flame. The band is placed in the same position on the 
 charcoal as in the previous method, and the large brush flame is 
 applied, holding it on the band until it begins to fuse. As soon as 
 the parts are united, the flame is quickly removed. 
 
 Fig. 217 
 
 Still another method is to invert the band, having the seam down- 
 ward. It is then caught lightly with a pair of soldering pliers and 
 held in the Bunsen flame and watched carefully until the gold 
 is seen to melt when it is quickly withdrawn (Fig. 217). The joint 
 is then hammered on the beckhorn of the anvil obliterating the seam. 
 This later method is perhaps easier than are the others and will 
 probably be favored by the majority of those doing this work. 
 
 CLEANSING GOLD AFTER ANNEALING OR SOLDERING. 
 
 A .'>() per cent, solution of sulphuric acid, technically termed 
 "jjicklc," is user! for cleansing tlic surface of gold after anneahng 
 
164 PROSTHESIS 
 
 and for removing the oxidation and fused flux after soldering. 
 This acts without heat if given sufficient time; it is usual, how- 
 ever, to keep the pickle in a porcelain evaporating disk mounted so 
 that it can be boiled, to hasten the operation. There is always 
 more or less unpleasant fumes given off by the acid, especially 
 when it is boiled. Where much work is done it is best to provide 
 a hood or small closet with a door which can be tightly closed, and 
 with a vent to the outside of the building to carry off the fumes, in 
 which to keep the acid. Small pieces can be boiled in a test tube 
 more conveniently than in the dish, they are, however, very fragile, 
 the work must be allowed to slide in gently, if dropped in the tube 
 will in all probability be broken. 
 
 Dilute hydrochloric or muriatic acid is also used for cleansing 
 the gold. It does the work equally well, but should never be used 
 except in a tightly closed closet as the fumes are most corrosive 
 and if left exposed will quickly ruin all the steel instruments 
 in a laboratory. 
 
 It is desirable to have at hand a solution of bicarbonate of soda 
 in which to rinse work taken from the pickle, especially if it is to 
 be immediately fitted in the mouth. It promptly neutralizes the 
 unpleasant acidity of the pickle. 
 
 When annealing small pieces of gold, or cleansing bands or 
 shell crowns preparatory to soldering, they may be brought to a 
 red heat and then plunged into the cold pickle, but where 
 porcelain is present it is necessary to boil the work. 
 
 A saturated solution of alum, used boiling, is quite satisfactory 
 for pickling, and very much more pleasant to use, although not 
 quite as convenient, as it must always be boiled. It may be kept 
 in a narrow lipped pitcher, and when required for use sufficient 
 to well cover the work poured into a porcelain or copper dish 
 in which it may be boiled. When the work is clean, the alum 
 solution is poured back into the pitcher and the work rinsed with 
 water while still in the dish. The alum solution is not corrosive, 
 as is the acid, and is not destructive to clothing, etc., if spilled. 
 
 GOLD ALLOYS USED FOR MAKING BANDS AND CROWNS. 
 
 The gold alloy used for making bands and crowns should be 
 sufficiently pliable to permit its accurate adaptation to the stump 
 or root, and at the same time should be hard enough, and possessed 
 of sufficient tensile strength so that there will be no liability of its 
 
RELATIVE MERITS OF CROWNS 1G5 
 
 stretching out of shape, and so defeating the object for which the 
 band was designed. It should also be of a sufficiently high carat 
 to withstand the oral secretions. 
 
 An alloy of gold and silver is more easily adapted than is a 
 harder alloy, but is too soft to give the best results, especially 
 for crowns used as anchorages for bridge-work. A tight fitting 
 band of this alloy driven over a stump is likely to become buckled 
 and distorted. A gold alloy possessing the properties of American 
 gold coin as regards strength, rigidity and elasticity, is more suit- 
 able for this purpose than is the ordinary twenty -two carat gold 
 of the dental depots. 
 
 Although coin gold is somewhat more difficult to manipulate 
 than is the other, it will make a far stronger and more lasting 
 band or crown, and is much to be preferred, especially if the band 
 or crown is used as an abutment for a bridge. 
 
 The copper in coin gold gives it a deeper color than has the 
 same carat with a large proportion of silver in the alloy. Some 
 object to it for this reason, but the w'riter prefers the deep rich 
 reddish color of the coin rather than the light lemon color of the 
 twenty-two carat gold plate of the dental depots. There is very 
 little difference in the carat of the two alloys, the coin being 21,6 
 carat, or 900 fine, and the other 22 carat, or 910 fine. 
 
 RELATIVE MERITS OF SWAGED SEAMLESS CROWNS AND 
 BUILT UP CROWNS WITH SOLID GOLD CUSPS. 
 
 There have been a number of outfits placed on the market for 
 making of seamless gold shell crowns. Some are more elaborate 
 than others, but there seems to be very little difl'erence in the 
 quality of the work done by these different devices. 
 
 The seamless shell crown does not meet the writer's approval. 
 It must be made of a soft metal, and therefore it possesses very 
 little strength, and should be used only as a temporary appliance. 
 
 In making these crowns, the metal, at every part except at the 
 gingival edge, is stretched during the operation of contouring and 
 forming the cusps, so that the metal necessarily becomes very 
 much thinner than it originally was, and this is especially true of 
 the metal on the occlusal surface of which the cusps are formed. 
 
 Many of these crowns are cemented in position without any 
 reinforcement of the occlusal surfaces, with the result that within 
 a very short time they are worn through, the cement is disinte- 
 
166 PROSTHESIS 
 
 grated, and the operation soon becomes a wreck. It should be 
 a general custom, when these crowns are used, before cementing 
 them in place, to flow solder into the caps, filling the cusps well so 
 as to stifi^en them and enable them to withstand the strain and 
 wear of mastication. 
 
 It not infrequently happens that in contouring and in form- 
 ing the cusps, that the gold is over-strained, and there will be 
 minute cracks in the fissures which extend entirely 
 
 lllpll, through the gold, but are so minute as not to be noticed. 
 
 rlBIBl ^^ flowing the solder into the cusps, it is rarely that 
 
 |m|||H) it will overflow the fissures which are the highest 
 
 points in the inverted cusps, but it will always drop 
 
 Fig. 218 {^to the cusps which are the deepest part of the crown 
 (Fig. 218). 
 
 When cemented in place, the crown may protect the tooth for 
 a time, but the moisture and fluids of the mouth will be carried 
 through these cracks in the fissures, disintegrating the cement, 
 causing decay and many times the tooth is entirely ruined before 
 the patient is aware that there is any thing the matter with it, the 
 same as when the cusps have been ground through. 
 
 This very often happens where a crown of this type is used for 
 an attachment for a bridge, another abutment perhaps holding 
 the bridge in place so that the patient is not conscious of any 
 change which may take place until it is too late to save the tooth. 
 
 Another objection to this crown as an attachment, aside from 
 the possible defects already mentioned is that a crown of this 
 type is not of suflficient strength to give support to a bridge. 
 Being made of such thin and soft material, if there is much stress 
 on the bridge, the side of the crown is frequently torn out at the 
 point where the dummies are united to it, and the whole piece is 
 rendered useless. 
 
 Again, if the crown is made to fit the stump, accurately contoured 
 as it should be contoured, and carefully articulated, it will take a 
 much longer time to make it with any of the seamless crown ap- 
 pliances that are on the market than it would to make an accurately 
 contoured and solid cusp built-up crown, while there can be no 
 comparison as to the strength and lasting qualities of the two 
 crowns. 
 
 As before stated, these crowns may be used for a temporary 
 protection of the natural crown of the tooth, but should not be 
 considered in permanent work. 
 
HOW TO USE THE SHEARS IN FESTOONING A BAND 167 
 
 HOW TO USE THE SHEARS IN FESTOONING A BAND. 
 
 In festooning a band, the flat side of the scissors or the inside of 
 the blade should always be placed next to the band. If cutting 
 to an outside mark, the edge which is being trimmed should be to 
 the left, the flat of the scissors placed against the edge and cutting 
 from the top of the band, as in Fig. 219. 
 
 Fig. 219 
 
 If cutting to an inside mark, as where the inside of the band 
 has been scribed around the top of the stump, this edge of the 
 band should be turned to the right, placing the flat of the scissors 
 on the lower side and following the marks (Fig. 220). 
 
 If the outside of the blade is placed against the metal, it will be 
 impossible to festoon it without distorting the band. 
 
 Fig. 221 shows curved crown shears. 
 
 Fig. 222 shows straight crown shears. 
 
168 
 
 PROSTHESIS 
 
 Fig. 220 
 
 Fig. 221 
 
 Fig. 222 
 
HOW TO USE THE SHEARS IN FESTOONING A BAND 169 
 
 Characteristics of the Cusps of Upper and Lower Bicuspid and 
 Molar Teeth. — In making a selection of cusp buttons or moulds 
 to serve as models from which to make the occlusal face of bicuspid 
 and molar crowns or in carving the cusps it is important to have 
 a general idea of the characteristic or typical form of the cusps 
 of the natural bicuspid and molar teeth. Although there are 
 slight variations, each normal tooth has certain characteristic 
 markings, or cusp forms, which indicate at a glance the position 
 it should occupy in the mouth. These will now be considered; 
 they should be borne in mind when selecting the model for or 
 carving the cusps of bicuspid and molar crowns. 
 
 Upper First Molars. — Looking at the first upper molar from the 
 occlusal surface, it will be seen that it is diamond-shape, the greatest 
 diameter being from the anterior buccal to the posterior palatal 
 corner (Fig. 223), and also in the outline drawing of Fig. 226, the 
 outside line showing the outline of the first molar. These teeth 
 have four cusps, the buccal and lingual being very different in 
 
 shape from each other. The lingual aspect of the buccal cusps 
 slope inward to the fissure on nearly a straight line, the mesio- 
 buccal and disto-buccal cusps being nearly of the same size and 
 with a prominent ridge near the center of each cusp; the buccal 
 occlusal points being fairly sharp (Fig. 224 a). 
 
 The lingual cusps, on the contrary, are large and well rounded 
 (Fig. 224 h), the disto-palatal being entirely separated from the 
 other cusps by a deep fissure extending from the middle of the 
 distal aspect to midway on the palatal side of the tooth (Fig. 223). 
 This cusp is distinctly different in shape from the others and will 
 always indicate on which side of the mouth the tooth belongs. 
 
 The Upper Second Molar. — In studying the upper second molar 
 closely ( I'ig. 22.")j, it will be found, on looking at the occlusal sur- 
 faces, that they are very nearly of the same shape as are the first 
 molars, with the exception that the diameter of the tooth from the 
 anterior buc(;al to the posterior j;alatal corner is slightly less pro- 
 portionately than it is in the first molar, as will be seen in the lines 
 
170 PROSTHESIS 
 
 in the drawing (Fig. 226), the middle line in the posterior palatal 
 corner representing the outline of the second molar. It is also to 
 
 Fig. 225 Fig. 226 
 
 be noticed that the disto-palatal cusp is smaller and not so well 
 defined as it is in the first molar. 
 
 The Third Molars. — With the third molar where there is the normal 
 number of roots, will be found the same general shape prevailing 
 as in the other molars (Fig. 227), but in the third molar the diameter 
 of the tooth from the anterior buccal to the posterior palatal is 
 still further decreased, and in many cases will be found to be less 
 than the disto-buccal to the anterior palatal (Fig. 226), the inner 
 line at the posterior palatal corner showing the outline of the 
 third molar. The disto-palatal corner also is still further rounded 
 so that the occlusal end of the tooth frequently presents a trian- 
 gular or rounded appearance rather than the typical diamond- 
 shape. Often, too, the disto-palatal cups will have almost entirely 
 
 Fig. 227 Fig. 228 Fig. 229 
 
 disappeared, but still in nearly every case, there is to be found 
 some trace of it, and the cusps may appear simply in rudimentary 
 form on the disto-palatal corner of the tooth, below the line of 
 the other cusps, as in Fig. 228. It is very rarely that all traces 
 of it are absent. 
 
 Where a number of upper molar cusp buttons, both for the 
 right and the left side have been mixed together, they can readily 
 be distinguished and separated by placing them on the table cusp 
 up, and with the buccal side toward the viewer. Take note of the 
 disto-palatal cusp, and whichever way that points, whether to 
 the right or the left, the cusp is for that side of the mouth (Fig. 
 229). A knowledge of this fact facilitates very much, not only 
 the separation of the cusp buttons of the right side from those 
 of the left, but the character of the palatal cusp, together with 
 
HOW TO USE THE SHEARS IN FESTOONING A BAND 171 
 
 the general outline of the crown, will indicate whether it be the 
 first, second or third molar. 
 
 Lower Molars. — In the lower molars, the shape of the crown 
 of the tooth is very different from that of the uppers. Viewed 
 from the occlusal surface, it is in the form of a parallelogram, the 
 mesio-distal diameter being much greater than the bucco-lingual. 
 It is also frequently slightly broader at the mesial side than at the 
 distal (Fig. 230). ' 
 
 Lower First Molar. — The lower first molar has five cusps and in this 
 instance we ha\e the reverse of the upper molar, the sharper cusps 
 being the lingual (Fig. 231 a) and the broad and rounded cusps being 
 the buccal (Fig. 231 b). This must of necessity be the case in order 
 
 b a 
 
 Fig. 230 
 
 Fig. 231 
 
 that there may be a perfect occlusion, as in Fig. 232. On the 
 buccal side there are three cusps, the mesial cusp and the middle 
 cusp being the larger. The fissure between these two is a little 
 anterior to the center, while the distal cusp is the smallest of 
 the three, the fissure extending generally from about one-sixteenth 
 of an inch from the disto-buccal side of the tooth diagonally toward 
 the center (Fig. 233). 
 
 Fig. 232 
 
 Fig. 234 
 
 The anterior sulci will be found fairly close to the mesial face of 
 the tooth, being broad and extending buccally and lingually across 
 al)out one-third to one-half of the width of the tooth. Distal ly 
 the fissure is forked, one branch separating the middle and distal 
 cusp and the other reaching in an oi)iK)site direction toward tlie 
 lingual side of the tooth. The shape of the cusps and the character 
 of the fissure are the distinguishing marks of these teeth. 
 
172 PROSTHESIS 
 
 Lower Second Molars. — In the second molar, there are but four 
 cusps, the two sharper cusps lingually, the two buccal cusps being 
 broad and rounded and of nearly equal size. This also has the 
 broadened fissure in the anterior part of the cusp, the same as 
 the first molar and also the fissure is forked distally, the structure 
 between the fork forming a rudimentary fifth cusp in the middle 
 of the distal side of the tooth (Fig. 234). 
 
 Lower Third Molars. — With the third molars or wisdom teeth, 
 the crown is generally smaller and narrower than are the other 
 two molars. The cusp may be similar in character to the second 
 molar, but this tooth is subject to a much greater variation than 
 are the other two, and in fact at times the character and arrange- 
 ment of the cusps are entirely different not only from any other 
 tooth in the mouth, but from any other human tooth. 
 
 The difference between the rights and lefts in the molars of the 
 lower jaw is not so marked as it is in the case of the upper, and 
 occasionally it is so slight that they may be used interchangeably. 
 This is especially true if it is desirable to cross the bite so that the 
 lower molars will bite outside the upper rather than on the inside. 
 In this case, the cusp of a right lower molar may be used on the left 
 side or that of a left may be used on the right, so as to bring the 
 broad buccal cusp on the lingual side, thus giving a broader occlusal 
 surface. 
 
 Again, the cusp might be reversed end for end so as to secure a 
 better occlusion, and then, after a little carving, it can be made 
 to represent the tooth which is being reproduced. 
 
 This interchangeability will very rarely work in the case of an 
 upper molar. It should be remembered in this connection, that the 
 one thing for which the operator is working is to restore the mouth 
 to as nearly a normal condition as possible, and in order to do this, 
 it is absolutely essential to secure the most perfect occlusion it is 
 possible to obtain. 
 
 The Upper Bicuspids. — In the upper bicuspids, as the name implies, 
 there are but two cusps, the buccal cusp being sharp, as in the case of 
 the buccal cusps of the upper molars, and very similar in character, 
 while the lingual cusps are more rounded, although not to the 
 same extent as are those in the molars. The first bicuspid is the 
 larger of the two, but the character of the cusps of the two are nearly 
 identical. 
 
 The Lower Bicuspids. — The first bicuspid has a long sharp buccal 
 cusp, but there is very little in the way of a lingual cusp. In fact, 
 this tooth often presents the appearance of a cuspid with simply a 
 
CONSTRUCTING A CONTOURED GOLD CROWN 173 
 
 rudimentary cusp on the lingual aspect of the tooth just above the 
 basilar ridge and is of no assistance in mastication. 
 
 With the second bicuspid, which is larger than the first, the 
 buccal cusp is not so high nor so sharp as that of the first. The 
 lingual cusp is broader and flatter than that of the first, and is 
 often divided so as to form what might be called a tricuspid. 
 
 Both the cusps of the upper and lower bicuspids may often be 
 used interchangeably for either side of the mouth, in order to secure 
 better results, and the character of the cusps of the opposite sides 
 is so similar that it is very rarely that the change would be detected. 
 
 CONSTRUCTING A BUILT UP CONTOURED GOLD CROWN 
 WITH SOLID GOLD CUSPS. 
 
 Taking the Measurement of the Root. — The measurement of the 
 stump or root should be taken straight across and as nearly at a 
 right angle with the sides as possible. It is very rarely that this 
 measurement should actually follow the gum line. Where there has 
 been a recession of the gum on one or more sides of the tooth, if the 
 wire with which the measurement is taken is carried down to these 
 points all around, it will be found that the band, when it is made, 
 will be too large to fit the stump. 
 
 As will be seen in the illustration of a lower molar where the 
 tissues are high at the back, but show a considerable recession 
 on the mesial side of the tooth (Fig. 235), if the measurement is 
 
 Fig. 235 
 
 taken following the line of the gum from a to b, when it is brought 
 up .so that it extends straight across following the line a to c, it 
 will be much larger than it should be. The wire .should be forced 
 as far under the gum distally as j)ossible and then brought straight 
 acro.ss to the point d. Then, too, in Fig. 236, showing an upper 
 molar with considerable recession of the tissues buccally and lingu- 
 ally, it can readily be .seen if the measurement follows the gum 
 line fn»m a to b that when it was .straightened out it would extend 
 from r to (I, with the result that a band marie to this measurement 
 would be much too large. 
 
174 
 
 PROSTHESIS 
 
 Built up Shell Crowns with Solid Cusps. — A built up crown, with 
 solid cusps, is the best and most enduring crown that can be made, 
 whether used as a single crown or as an abutment for a bridge 
 (Fig. 237). _ 
 
 Where it is necessary to restore very much contour (Fig. 238), 
 the band should be cut on a bevel, measuring from the gingival 
 
 Fig. 237 
 
 Pig. 238 
 
 edge and flaring it outward toward the occlusal, the amount of 
 the flare depending on the amount of the contour which is to be 
 given to the crown (Fig. 239). Where the adjoining teeth have 
 
 Fig. 239 
 
 Fig. 240 
 
 Fig. 241 
 
 closed in on the stump, and there is very little or no contour to be 
 restored, as in Fig. 240, the ends of the band may be cut parallel 
 with each other (Fig. 241). If in this case, the band were cut on 
 a bevel and made larger at the occlusal end, when forced onto 
 
 Fig. 242 
 
 Fig. 243 
 
 Fig. 244 
 
 the stump it would be squeezed together mesially and distally 
 and forced out buccally and lingually beyond the line of the adjoin- 
 ing teeth as in Fig. 242. 
 
 One end of the band is then beveled to a knife edge and the 
 ends are brought together and sweated or soldered. The band 
 should now be given the approximate shape of the tooth which is to 
 
CONSTRUCTING A CONTOURED GOLD CROWN 
 
 175 
 
 be crowned (Figs. 243 and 244) and is next roughly festooned so 
 as to follow the gum line approximately (Fig. 245). 
 The shaping of the bands is best done with the 
 collar pliers shown in Figs. 246 and 247. The beaks 
 of Fig. 246 are very narrow, one having a flat face, 
 the other being rounded and slightly shorter than the 
 other. Fig. 247 is made on the same plan, having 
 one flat and one rounded, but the beaks are much 
 broader than Fig. 246. Fig. 246 is used in shaping fig. 245 
 
 I'n^. 24G — Pccso pliers. 
 
 Fig. 247— Kobinson pliers. 
 
176 PROSTHESIS 
 
 lower incisors and other small bands, and Fig. 247 for molar, 
 central incisor and cuspid bands. 
 
 The band is placed on a stump and scribed around on the out- 
 side with a sharp instrument following the gum line carefully (Fig. 
 245), after which it is removed and trimmed to the line and the 
 outer edge bevelled so that it will pass under the gum without irri- 
 
 FiG. 248. — In using the file, the band should be held gingival edge up and filed 
 from the inside outward so as to throw the feather edge to the outside, leaving 
 the band smooth on the inside. The feather edge is afterward removed by beveling 
 the edge of the band on the outside. 
 
 tating it. It is then replaced on the stump and forced well down 
 over it. It is again marked, and removed and with a fine file accu- 
 rately shaped to the gum line, so that it will pass, evenly, about 
 one-sixteenth of an inch beneath the gum all around (Fig. 248). 
 After it is accurately in position the impression is taken. 
 
 The model is cast and prepared as already described when treating 
 
CONSTRUCTING A CONTOURED GOLD CROWN 177 
 
 of making models. The band is removed by warming it slightly or 
 by grasping it with a pair of warm pliers which softens the wax 
 and allows it to come away from the model. The remaining wax 
 should be burned awRv and the band cleansed in dilute sulphuric 
 acid. The wax should also be removed from around the stump 
 on the model. 
 
 Contouring the Band. — The stretching of the band for contouring 
 may be done on the beckhorn of the anvil or with the stretching 
 and contouring pliers (Fig. 211) as previously described. In 
 stretching the band, whether with the pliers or on the anvil, it is 
 started at a point slightly above the gingival edge, working around 
 the banil from this point and gradually increasing the pressure 
 as the occlusal end is approached, giving the band something 
 of a bell-shape, until it is flared somewhat more than enough to 
 give the required contour (Fig. 249). 
 
 In using the pliers, one beak of which has a broad flat face, while 
 the other is narrow and has a round face, the smaller beak is placed 
 
 Fig. 249 Fig. 250 
 
 inside the band and the larger flat faced beak on the outside; 
 the stretching is done by closing the handles lightly and working 
 around the band, gradually increasing the pressure as the work 
 progresses from the gingival to the occlusal end. 
 
 The band is then annealed, and with a pair of Robinson pliers 
 (Fig. 247) the occlusal end is straightened so as to give the desired 
 broad point of contact with the adjoining teeth. The edge should 
 not be tipped inward in the least, but the sides should be brought 
 so that they are parallel with each other for approximately about 
 one-third the length of the band, as in Fig. 250. 
 
 If the band is simply stretched and not straightened up toward 
 the occlusal end, it will be seen by the illustration, that if the cusp 
 was soldered on and the crown completed, the point of contact 
 would be very slight and the crown would not in the least resemble 
 the crown of a natural tooth (Fig. 251). 
 
 If the shaping of the band is done with a pair of contouring pliers, 
 and the edge turned in too much at the occlusal end, when the 
 12 
 
178 
 
 PROSTHESIS 
 
 cusp is in place, the point of contact will be below where it is united 
 to the band, leaving a groove extending around the whole crown 
 at the point of union of the cusp, giving the crown something of 
 a door-knob effect (Fig. 252). 
 
 After the occlusal end of the band has been straightened as 
 described above, it is shaped so as to bring out the normal contour 
 
 Fig. 252 
 
 
 'H, \ - 
 
 ^-j-^ 
 
 >3 t 
 
 r-- c 
 
 Fig. 254 
 
 of the tooth and to bring it in close contact with the adjoining 
 teeth (Fig. 253). The occlusal end is filed perfectly flat and it is 
 then ready for the cusp. 
 
 The Making of the Cusp. — There are many different methods of 
 making the cusp, any one of which may be indicated in certain 
 cases. One method is to carve the cusp in wax, modeling com- 
 position, or plaster. A fusible metal die and counter die is then 
 
CONSTRUCTING A CONTOURED GOLD CROWN 
 
 179 
 
 made and a matrix of very thin pure gold, about three one- 
 thousandths of an inch in thickness, is swaged from this and 
 filled with coin gold or the trimmings from the band. 
 
 Another method is to have a supply of cusp buttons, similar to 
 those used in the Hollingsworth system (Fig. 251). These buttons 
 consist of a thin copper matrix filled in with soft solder. There 
 are many good cusp buttons supplied with the Hollingsworth 
 System, but they can be added to very easily by the dentist himself, 
 as it is impossible to have too many of these buttons. 
 
 liii 
 
 ' Fig. 255 
 
 In making cusp buttons an impression is taken, and a model 
 [>r(;par('d of any cusp which it is desired to rej)roduce, and a die 
 and ccjuntcr die made of fusible m(;tal. The matrix is made of very 
 thin brusli copper, about No. .'iO-gauge, which can generally be 
 obtained at an electrical supply house. This is well annealed and 
 .swaged between the die and counter die, carefully l)urnishing out 
 any wrinkles which may appear. 
 
180 
 
 PROSTHESIS 
 
 It may be necessary to anneal the copper two or three times 
 during the operations. After a perfect matrix has been obtained, 
 it is thoroughly cleansed. This may be done by heating and 
 dipping it in a 50 per cent, solution of alcohol and water. It is then 
 fluxed with zinc chloride and filled in with tinner's half and half 
 soft solder. This is very easily done by using 
 the solder in the form of wire. The margin of 
 Fig. 256 the cusp matrix should be left until after it has 
 
 been filled and the excess filed away. 
 The cusp matrix is first fluxed with zinc chloride and then 
 grasped with a pair of pliers and held over the flame of a Bunsen 
 burner, and the wire solder fed in (Fig. 255), using enough so as 
 to leave the surface slightly convex (Fig. 256), after which it is 
 thoroughly cleansed with water to wash away the zinc chloride. 
 Then the cusp button is laid on a very coarse flat file, grasped in 
 
 Fig. 257 
 
 the fingers, and rubbed back and forth, the extending surplus of 
 the copper matrix protecting the fingers (Fig. 257), and the sur- 
 plus solder is filed away until the under surface is perfectly flat. 
 
 After it is filed perfectly smooth and flat, the cusp button is 
 completed by trimming and smoothing the edges (Fig. 258). 
 
 By having a large selection of these cusp buttons, one can gener- 
 ally be found which will so nearly fit the case in hand as to require 
 but slight changes. It should be slightly larger than the band. 
 If there are any points which need raising they can 
 be built up with hard wax and suitably carved. 
 
 A pure gold matrix for a gold cusp is made by 
 
 using one of the swaging devices to be procured at 
 
 any dental depot. They consist of a base with a 
 
 raised anvil, a heavy metal tube passing over the anvil with a 
 
 soft rubber plunger which fits into the tube and over this a metal 
 
 plunger (Fig. 259). The pure gold used for the matrix is about 
 
 Fig. 258 
 
CONSTRUCTING A CONTOURED GOLD CROWN 
 
 181 
 
 three one-thousandths of an inch in thickness. This, when the 
 gold is doubled, will fit into No. 34 Brown and Sharpe gauge. 
 A piece of this pure gold, a little larger than the button, is 
 
 Vu:. 2.Vi 
 
 annealed and pressed over the })utton as it lays on the anvil 
 (Fig. 259). The metal cylinder is then put in j)lace and the 
 
182 
 
 PROSTHESIS 
 
 rubber dropped into it on top of the pure gold, and over this 
 the steel plunger. The swager is then placed on a large anvil and 
 the plunger is struck a sharp blow with a heavy hammer.^ The 
 
 
 Fig. 260 
 
 matrix will be a perfect reproduction of the button which has 
 been used. This matrix is now filled with coin gold. 
 
 Filling the Cusp Matrix.— The trimmings of the band and other 
 scraps of coin gold are fused into a button sufficiently large 
 
 1 A rawhide hammer, or a hammer having a fiber face is best, as it will not mar 
 the plunger as does a steel hammer. 
 
CONSTRUCTING A CONTOURED GOLD CROWN 
 
 183 
 
 to fill the matrix. The matrix is placed on the charcoal block, 
 cusp side down, and the heated ball of gold is placed in it 
 and fused with the blow-pipe. This can be done by using 
 a brush-flame, care being taken not to use more air than is 
 necessary to keep the flame steady, holding the blow-pipe about 
 two and one-half to three inches above the button of gold, using 
 a steady pressure of air, just enough to carry the flame to the 
 button and curl a little at the end, as in Fig. 260. The flame is 
 flashed oft' for an instant, if the matrix becomes over-heated, and 
 
 Fig. 261 
 
 Fig. 262 
 
 then back again, repeating this as may be necessary until the 
 gold is melted and fills the matrix. This slow soft flame will give 
 sufficient heat to melt the coin gold, but not the pure gold matrix, 
 which has a higher fusing point, unless it is held in one place for a 
 long time. 
 
 To successfully fill a thin i)ure gold matrix with coin gold requires 
 care, but a little careful practice with the blow-pipe will enable 
 one to accompli-sh it with very little danger of burning. If too 
 much air is used, it will give a hotter flame, and perhaps l)urn the 
 matrix. The pure gold, being of a higher carat, with a slightly 
 
184 
 
 PROSTHESIS 
 
 higher fusing point, will withstand a greater heat and allow the 
 coin gold to melt and fill the matrix, provided the heat is con- 
 centrated upon the coin gold. 
 
 The cusp matrix can also be filled by keeping a small hot 
 blue flame on the button of coin gold until it melts and fills the 
 cusp (Fig. 261), but care must be exercised to keep it on the coin 
 gold all the time, because if it should be moved a little to one side, 
 
 Fig. 263 
 
 so that the flame strikes the pure gold, it will be promptly burned 
 as it is so very thin, and the flame so very hot. After it has been 
 properly filled, it is cleansed and the under surface of the cusp is 
 filed perfectly flat (Fig. 262). 
 
 In order to file this surface easily, the cusp should be held 
 firmly. This can best be done by setting it in the end of a soft 
 pine stick. The cusp is laid, flat side down, on an anvil, the 
 end of the soft pine stick resting upon it, and the stick struck a 
 
CONSTRUCTIXG A CONTOURED GOLD CROWN 
 
 185 
 
 sharp blow, with a mallet or hammer, thus driving the cusp into 
 the wood (Fig. 263). 
 
 Another method is to heat the cusp red hot and place it on an 
 end of the stick, cusp down and let it burn its way into the wood 
 until it is nearly flush. Either method will hold the cusp firmly, 
 so that it can be easily filed. 
 
 Uniting the Cusp to the Band. — After filing, the cusp is wired to 
 the band in its proper position, the wire being brought over the cusp 
 and across the gingival end of the band, and twisted in the center 
 so as to draw and hold the cusp in contact with the edge of the band. 
 
 Fig. 265 
 
 Then the line of contact between the band and the cusj) is well 
 fluxed. 
 
 The twisted ends of the wire are grasped in a pair of pliers and 
 the crown held over the tip of a Bunsen flame (Fig. 204). As the 
 cusp b(;comes thoroughly heated and the gold almost reaches the 
 fusing j>(>iiit, the crown is lowered slowly toward th(; center of 
 the flame (Fig. 265). By watching it carefully a dark line appear- 
 ing like flowing solder, will seem to flash around the cusp where 
 
186 PROSTHESIS 
 
 it joins the band. This is the metal melting, and indicates that 
 the cusp and the band are perfectly united. 
 
 As before stated, the crown should be held to the tip of the flame 
 until the cusp has become thoroughly heated. If it is at once 
 lowered into the flame, the cusp, being so thick and heavy, 
 becomes heated very slowly, and the flame passing up around its 
 sides would melt and ruin the lighter band before the cusp was 
 hot enough to be sweated to it. 
 
 It should be remembered, that in sweating, the parts to be 
 united should be brought to nearly the same degree of heat, other- 
 wise one part will melt before the other, and there will be no union. 
 
CHAPTER X. 
 THE MAKING OF THE CROWxXS. 
 
 RICHMOND OR PORCELAIN-FACED CROWNS. 
 
 In making a banded crown for any of the teeth in the anterior 
 part of the mouth, the stump should be left standing from one- 
 thirty-second to one-sixteenth of an inch out of the gum, until 
 after the root has been trimmed and the band fitted. 
 
 After trimming, the measurement of the root is taken with a wire, 
 straight across, at right angles to the long axis of the root (Fig. 266). 
 It should not follow the festoon of the gum line, 
 as that would carry the measuring wire lower on 
 the buccal and lingual sides than on the mesi«,l and 
 distal, bringing it on a curve so that when the wire 
 was straightened out it would be larger than the cir- 
 cumference of the root. 
 
 The gokl strip is cut, to measurement, with the 
 ends parallel with each other so that when the band 
 is made the sides will be parallel. One end is beveled and the 
 lap made, and the band is sweated together and afterwards shaped 
 and fitted to the stump, as in the case of the molar crowns already 
 described. 
 
 Fig. 266 
 
 Fig. 207. — Kirk's dentinictcr, suilablo lor t:ikiiiK flu; moasuremcnt of roots. 
 
 It should be carried well under the gum, especially on the labial 
 side, being festooned carefully to follow the gum line (Fig. 2()8). 
 After the band has been fitted it is removed and the root faced 
 off, cutting well beneath the gum on the labial side so that the 
 band will be entirely hidden. This ordinarily woukl be carried 
 about one thirty-second of an inch below and at times even to a 
 greater depth if the conditions are such to allow of its being done. 
 
 This work is accomplished with the root facers in the manner 
 
188 
 
 THE MAKING OF THE CROWNS 
 
 already described, after which the band is replaced on the stump 
 and forced up as far as it will go. It is then scribed around on the 
 inside, jBush with the face of the stump, with a sharp instrument. 
 The band is now removed and trimmed and filed to this line with 
 
 Fig. 268 
 
 Fig. 269 
 
 a very fine flat file. The cutting and filing must be done very 
 carefully, as the band, being narrow and frail, is easily bent out of 
 shape. After filing, it is again tried on the root, so as to be sure 
 that it has not become distorted, before sweating on the floor 
 (Figs. 270 and 271). 
 
 Fig. 270 
 
 Fig. 271 
 
 It is not necessary that the band be wide on the labial side. 
 In fact it is rarely that it should be more than one-thirty-second of 
 an inch in width at this point. It is only necessary that it extend 
 over far enough to get a good grip on the root, but great depth is 
 
RICHMOND OR PORCELAIN-FACED CROWNS 
 
 189 
 
 not essential, as the greatest strength of the band is at the point 
 nearest to the floor. 
 
 The band being properly filed, a piece of coin gold, Xo. 30 gauge, 
 is prepared about one-sixteenth of an inch larger than the band. 
 This is made perfectly flat. A little swaging device is used for this 
 purpose, consisting of a steel anvil with a flat, smooth face, inserted 
 in one end of a brass tube and having a steel plunger with a per- 
 fectly flat polished face which fits into the tube (Fig. 271). 
 
 The metal for the floor is annealed and then placed on the center 
 of the anvil at the bottom of the tube. The steel plunger is then 
 inserted into the tube over the gold and tapped with a hammer 
 until the metal is perfectly flat. 
 
 The gold is then cleansed in acid. The band is now placed on 
 this piece of gold so that it extends about an even distance from the 
 edges all around. It is fluxed, one corner 
 of the floor grasped in a pair of pliers and 
 held in the Bunsen flame until it is sweated. 
 The band and floor being of about the 
 same thickness, it should be held near the 
 middle of the flame, so that the flame will 
 spread and come up around and over the 
 cap, heating both the band and the floor 
 equally (Fig. 272). 
 
 As the piece is held in the flame, the 
 edges of the floor will begin to melt and 
 curl up slightly, just as the floor and 
 band reach the fusing point. When this 
 is seen it is removed from the flame. 
 
 It will generally be found that at the corner where the floor was 
 grasped by the pliers, the band and floor have not been united, 
 owing to the pliers drawing the heat from the gold at this point. 
 The floor is again caught by the opposite corner and held in the 
 flame until the two parts are thoroughly united all around. The 
 surplus metal of the floor is now trimmed flush with the side of the 
 baiul. It is then ready for the pin. 
 
 Where to Drill the Hole in the Floor of the Cap for the Pin. — There 
 are several ways of locating the point at which to drill the hole 
 for the pin in the floor of the cap. Some operators use wax on the 
 under side of the cap and press the cap on the root, the i)osition 
 of the hole is thus marked on the wax. Others, place in the root a 
 short post with a sharpened end projecting just above the face of 
 
 Fig. 272 
 
190 
 
 THE MAKING OF THE CROWNS 
 
 the root, so that when the cap is forced in place it will make a 
 mark over the opening. But such methods are not necessary and 
 take up valuable time. 
 
 In the six anterior teeth the canals are exactly in the center of 
 the root. In enlarging the canal for a post for a Richmond crown, 
 after having followed the canal, the reamer is partly withdrawn and 
 the canal given a lingual slope, cutting it in that direction about the 
 width of the pin lingually from the original line of the enlarged 
 canal (Fig. 273). In making the hole in the floor of the cap, first 
 locate the center of the floor and then drill, or punch the hole in the 
 floor just the width of the post lingually (Fig. 274), and then by 
 giving the post a slight bend, to follow the canal, it will pass 
 through the floor, far enough from the buccal side to allow of 
 plenty of room for the facing. This will apply to any of the six 
 anterior teeth. When making a porcelain crown, the hole is 
 
 Fig. 273 
 
 Fig. 274 
 
 Fig. 275 
 
 Fig. 276 
 
 drilled exactly in the center of the floor and we know of a cer- 
 tainty that the post will be in its proper position. 
 
 The pin for a first bicuspid crown, should always be placed in the 
 lingual root. Unless the stump has been broken or decayed far 
 below the gum so as to make the two roots very short, there is no 
 necessity for using more than a single pin. The force exerted on 
 these teeth is always upward and outward, there being practically 
 no stress at all in the lingual direction (Fig. 275). If a single pin 
 were placed in the buccal canal, the force being outward and upward, 
 it would tend to loosen the crown from the lingual side, perhaps 
 enough so that the edge of the band would clear the root at this 
 point, with the result that the crown would be forced outward, 
 and would almost certainly fracture the buccal side of the root 
 (Fig. 276). 
 
 If the post be placed in the lingual root, the cap is bound down 
 
RICHMOND OR PORCELAIN-FACED CROWNS 
 
 191 
 
 tightly at that point, and there is but Httle risk of its being forced 
 outward, or being loosened from the buccal side, as the force of 
 mastication will keep it pressed tightly against that face of the root 
 (Fig. 277). 
 
 Fig. 277 
 
 Fig. 278 
 
 Fig. 279 
 
 Fig. 280 
 
 In order to locate the opening in which to place the pin in these 
 roots, follow out the lingual curve to a complete circle on the floor 
 of the cap, and drill the hole exactly in the center of this circle. 
 The pin will then enter the canal freely (Fig. 278). 
 
 The second bicuspid, has but a single root, but this is broad and 
 flat, and there is more leeway than in the first bicuspid. In this 
 case drill the hole a little lingually from the center, having enlarged 
 the canal along this same line. It will also give more room in 
 which to place the pin, as the root is somewhat constricted in 
 the center (Fig. 279). 
 
 In grinding the facings for the Richmond crowns, it is better 
 that they should be ground flat to fit the floor of the cap (Fig. 280), 
 especially in the six anterior teeth where there is a likelihood of 
 the gold being seen from the front if the facings are beveled so 
 
 Fia. 281 
 
 Fig. 282 
 
 Fig. 283 
 
 as to just come in contact with the Hof)r only at the labial side 
 (Fig. 281 J. With the bicuspids there is not the same likelihood of 
 
192 THE MAKING OF THE CROWNS 
 
 the gold being visible between the necks of the teeth, so there is no 
 objection to beveling the lower part of the facing, if it is desired. 
 
 The hole in the floor having been located and drilled, the cap is 
 placed on the root and the pin put in position, carrying it as far 
 down the canal as possible, waxed in place, removed, invested and 
 soldered (Fig. 282). These pins are preferably made of round 
 platinized gold clasp wire, and should be of about No. 14 to 16 
 gauge, the size of the pin depending on the tooth which is to be 
 crowned. 
 
 Backing and Soldering. — The backings for these teeth are pre- 
 ferably made of soft platinum about three or four one-thousandths 
 of an inch in thickness. Crown metal plate which has one surface 
 of gold and the other of platinum may also be used. If it is desired 
 to lighten the shade of the tooth, the gold side is placed next to 
 the facing. The backings should fit the facing closely and extend 
 from the lower edge of the lingual side of the facing to about one- 
 sixteenth of an inch beyond the incisal edge, as in Fig. 283. The 
 pins are flattened and then bent upward toward the incisal edge 
 and against the backing, thus holding it close to the facing. The 
 pin roughing and bending pliers are used for this purpose and are 
 shown in Fig. 284. 
 
 Fig. 285 shows a small wax spatula especially adapted for light 
 work of this kind. 
 
 The facing is waxed in position on the cap with sticky wax. 
 After it has chilled, it will be found that the contraction of the 
 wax on cooling has tilted the facing slightly so that it rides on 
 the cap on the lingual side of the ground portion of the facing 
 raising its labial side clear from the floor of the cap (Fig. 286). 
 If it were soldered without remedying this defect, the facing would 
 be still further drawn from the floor on the labial side, due to the 
 contraction of the solder, leaving a V-shaped space between the 
 facing and the floor of the cap. 
 
 To overcome this difficulty, after the facing has been waxed, 
 it should be pressed outward at the incisal edge until the labial 
 side presses on the floor of the cap, and the lingual side is just 
 clear of it, so that if it is held up to the light, it can be seen that 
 it is not in actual contact at that point (Fig. 287). If this has 
 been done, when the crown is soldered, the contraction of the 
 metal will draw the facing close to the floor on the lingual side, 
 without disturbing its contact on the labial side, thus making a 
 perfect joint. 
 
RICHMOND OR PORCELAIN-FACED CROWNS 193 
 
 Fig. 284 
 
 13 
 
194 
 
 THE MAKING OF THE CROWNS 
 
 The investment should be only large enough to hold the parts 
 in position (Fig. 288). A small amount of the investment is placed 
 on the slab and smoothed, as in soldering a porcelain crown. The 
 inside of the cap is filled with investment and laid face down on 
 
 Fig. 285 
 
 the investment which has been placed on the slab and settled in 
 place until the lingual side of the facing is exactly flush. The pin 
 is covered with investment and the extending backing on the 
 incisal edge is also covered, bringing it flush with the lingual side 
 of the facing, as in Fig. 289. 
 
 Fig. 286 
 
 Fig. 287 
 
 After the investment has hardened, it is warmed slightly and the 
 wax removed, after which it is heated thoroughly, and soldered. 
 No more solder should be used than is necessary to restore the 
 normal contour of the tooth, but the incisal edge should be covered 
 thickly. After it has cooled, it is removed from the investment, 
 cleansed in acid and finished. 
 
 
 Fig. 288 
 
 Fig. 289 
 
 The gold at the incisal edge should be left as thick as the bite 
 will permit, in order to protect the facing, and it should be ground 
 so as to leave it a little higher on the lingual side, but not enough 
 so that it can be seen (Fig. 290). 
 
PORCELAIN CROWNS {DOWNEY CROWNS) 
 
 195 
 
 The normal shape of the tooth should be restored as nearly as 
 possible. The lingual surface of the incisors should be made con- 
 cave from the incisal edge for about half the length of the crown 
 (Fig. 291), and not convex as is so frequently done (Fig. 292). 
 
 The Richmond or pin crowns, and shell crowns are the principal 
 attachments used in fixed bridge-work. 
 
 Fig. 290 
 
 Fig. 291 
 
 Fig. 292 
 
 PORCELAIN CROWNS (DOWNEY CROWNS). 
 
 In making a so-called Downey crown for any of the six anterior 
 teeth, where a facing is used, and the lingual side built up with 
 porcelain, the root is given a double slope in the manner already 
 described, cutting well beneath the gum labially and carrying it 
 just about to the gum on the palatal side (Fig. 293). 
 
 The cap is made of iridio-platinum plate. No. 32 gauge, and in 
 the same manner as the cap of a Richmond crown, with the ex- 
 
 Fig. 29.3 
 
 Fh;. 294 
 
 Fig. 295 
 
 ception of its being soldered with pure gold and lia\iug a double 
 slope (Fig. 294;. 
 
 The pin is placed exactly in tiic center of tlie cap, and the facing 
 ground so that the gingival end touclies the Hoor lightly at the labial 
 side only fFig. 29.')). 'i'his will allow of the porcelain body being 
 worked inidcr the faring n'lorc readilx' than if the facing had a broad 
 C()ntact with the floor. The fiiciiig iii;iy be grooved out between 
 the pins to permit of l\\v. post setting well into the facing (i^'ig. 
 
196 
 
 THE MAKING OF THE CROWNS 
 
 296), allowing plenty of room on the palatal side for the porcelain 
 body. The two pins may be notched slightly with the edge of a 
 small half-round file (Fig. 297) toward the incisal end to allow of 
 their being bent flat against the facing, and bring them in contact 
 with the sides of the post (Fig. 295). They should not be bent 
 out and around the post, as this would frequently carry them so 
 far lingually as to show through the porcelain, and consequently 
 weakening the crowns. 
 
 Fig. 296 
 
 Fig. 297 
 
 After the pins are bent in contact with the sides of the post, 
 they are waxed firmly with hard sticky wax. A small amount of 
 wax should be flowed around the labial edge of the band between 
 it and the facing to prevent any of the investment material from 
 working in between the facing of the cap. 
 
 In investing this, for soldering the pins to the post, a small amount 
 of investment is placed on the slab and smoothed off perfectly 
 flat, leaving it from about three-eighths to one-half an inch in 
 
 Fig. 298 
 
 Fig. 299 
 
 thickness. The crown is then laid face down on the investment 
 and pressed lightly until it is imbedded even, or flush, with the 
 lingual side of the facing. A little of the investment is then placed 
 over the end of the pin to hold it in position (Fig. 298). 
 
 No investment should be placed inside of the cap. This should 
 be kept perfectly clear, the bulk of the pin and the cap being exposed 
 to the flame. If the cap is filled with investment material, and the 
 post and cap thoroughly covered, as in the illustration (Fig. 299), 
 
JACKET CROWNS 197 
 
 it will require a greater length of time, and much more heat to unite 
 the pins to the post, as there would then be such a large mass 
 of investment to heat up. The investment taking the heat from the 
 post, would make it very difficult to get it hot enough to solder the 
 pins of the facing to it with pure gold. On the other hand, if the 
 cap and the larger part of the post is left exposed, as soon as the 
 investment is heated up to a red heat, by throwing the flame on 
 the metal parts, the pure gold will quickly flow in. between the 
 pins and the post. 
 
 The flame of the blowpipe should never be thrown on the metal 
 parts until after the investment and facing are thoroughly heated 
 to a bright red heat, otherwise the facing will be broken, owing to 
 the sudden expansion of the platinum pins. After it has been sol- 
 dered, it is cleansed in acid and is ready for the application of the 
 porcelain body. 
 
 HALF CAPS OR WINDOW CROWNS. 
 
 The half cap, or window crown, was at one time used quite 
 extensively as an anchorage for bridges. It was very unsightly 
 and was a very poor attachment to say the least, and while at 
 the present time there are some who still use it, it is becoming 
 obsolete, so that it would be a waste of time to go into a description 
 of its construction. 
 
 JACKET CROWNS. 
 
 The jacket crowns are designed to be used where it is desirable 
 to avoid devitalizing a tooth. They are indicated when it is 
 necessary to crown peg-shaped laterals or unde- 
 veloped teeth of a similar character, where the 
 crowns are very small, or where the crowns of 
 teeth are much decayed, and the pulps have 
 receded (Fig. 300). ^'°- ^^^ 
 
 The method of making these crowns varies according to conditions 
 to be met, and the materials used in their construction. 
 
 VVhere the crowns are needed for much decayed anterior teeth, the 
 labial face of the tooth is ground awa}- as much as possible without 
 endangering the life of the pulp, cutting well under the gum, as in 
 Fig. 301. The enamel is also removed from the sides and palatal 
 portion so that the band will hug the root tightly under the gum. 
 The band is then made and fitted to the stump and cut out on the 
 labial side flush with the tooth (Fig. 302). The palatal side of the 
 
198 
 
 THE MAKING OF THE CROWNS 
 
 band is pressed in close to the stump and the mesial and distal 
 sides of the band spread out nearly to the width of the facing which 
 is to be used, and a floor of coin gold sweated or soldered to it 
 (Fig. 303). A thin facing is then ground so as to leave a little space 
 between it and the cap, touching the latter only at the gingival end 
 
 ) 
 
 Fig. 302 
 
 Fig. 301 
 
 Fig. 303 
 
 (Fig. 304) . The facing is now backed with thin platinum or crown 
 metal, which is allowed to extend about one-sixteenth of an inch 
 beyond the incisal edge. It is then waxed to the cap, invested 
 and soldered, flowing the solder between the facing and the cap 
 and if necessary over the palatal portion of the band (Fig. 304). 
 
 Another method of making the jacket crown 
 
 . is to carry the band to the full height of the 
 
 /\ /] tooth, to contour it, and cut it out on the face 
 
 j|M I/* to the depth of the facing. The facing is then 
 
 ^^ ^ ground to fit the edge of the cap so formed 
 
 Fig. 304 Fig. 305 and a backing of coin gold fitted carefully to it (Fig. 
 
 305) . This backing with the facing in position, 
 
 is then adjusted to the cap, waxed, the facing removed and the 
 
 backing sweated, or soldered to the cap with 22 carat solder (Fig. 
 
 306) . The facing is then put in place, the pins waxed on the inside 
 
 of the cap, and the crown invested. The crown is invested face 
 
 down and covered but lightly, leaving the opening fully exposed, 
 
 Fig. 306 
 
 Fig. 307 
 
 Fig. 308 
 
 as in Fig. 307. It is thoroughly dried out and flux placed on and 
 around the pins. A piece of 18 or 20 carat solder is then placed 
 over the pins, the whole brought to a brigth-red heat, and with 
 the fine blue point of the blow-pipe flame thrown on the inside, 
 the solder is melted, uniting the facing to the cap. Fig. 308 shows 
 the completed crown. 
 
CASTING PROCESS IN CROWN WORK 199 
 
 In making a porcelain-faced crown for a bicuspid having a vital 
 pulp, the tooth is prepared in the same way as for an anterior 
 tooth, cutting it well out on the buccal side, and grinding away 
 the inner cusp (Fig. 309) . The band is then made as for a full gold 
 crown, and cut even with the cusp at the top and enough on the 
 buccal side to allow for the facing (Fig. 310). The facing is then 
 ground to fit the edges of the cap (Fig. 311), and a backing of 
 coin gold fitted to it. The backing being fitted to the facing, 
 it is placed in position on the cap and waxed and soldered with 
 22-carat solder. The backing is then cut oft' even with the rest 
 of the band and filed flat (Fig. 312). The tip of 
 the facing is then ground on a bevel with an angle 
 of about 45°, the lower edge of the bevel being on 
 a line with the top of the cap (Fig. 313). 
 
 A cusp is then selected, the under surface filed 
 flat and the buccal side beveled to meet the bevel 
 of the facing (Fig. 314). The cusp is then wired to Fig. 309 
 
 the cap and soldered with 22-carat solder, the facing 
 having first been removed. The cap is then cleansed in acid and 
 the facing replaced in position and waxed. It is then invested and 
 soldered from the inside as already described in Fig. 307. The 
 jacket crowns described can be used as abutments in fixed bridge 
 work. 
 
 Where it is desired that the crown should be of all porcelain, 
 the cap should be made of soft platinum, No, 32 gauge, and 
 fitted carefully to the stump all around. The facing is then ground 
 
 ^ 
 
 Fici. 310 Fig. 311 Fig. 312 Fig. 313 Fig. 314 
 
 in place and attached to the caps by means of the pins soldered to 
 it with a very minute quantity of pure gold, after which the crown 
 is completed by building up with porcelain. 
 
 THE CASTING PROCESS AND ITS AVAILABILITY IN CROWN 
 
 WORK. 
 
 The introduction of the casting jiroccss opened up a large field 
 in this braric-h of prosthesis, but it must be employed with a full 
 
200 THE MAKING OF THE CROWNS 
 
 recognition of its limitations. Cast gold is not as strong as rolled 
 gold, and a bridge of cast gold is not as strong as one built up and 
 soldered. The shrinkage of the metal in cooling must also be taken 
 into account or failure on that score is sure to result. 
 
 The metal used for this work should be of a high carat, and of 
 as great tensile strength and rigidity as possible. It should not be 
 overheated. Coin gold appears to be well adapted for this purpose 
 as it possesses the qualities above mentioned and gives a good 
 sharp casting. 
 
 All Porcelain Crown with Cast Base. — This, being one of the simplest 
 and easiest crowns to make, will be first considered. The root 
 for a crown of this character requires little preparation, as com- 
 pared with one for a Richmond or other banded crown. The face 
 of the root may be irregular from decay or fracture, or it may have 
 been ground down to meet the requirements of the case. In any 
 event, it should be cut well beneath the gum line on the labial side, 
 and on the lingual side enough to suit the requirements of occlu- 
 sion. The lingual side should, if it is possible, be beveled so that 
 the base will overlap, thus giving additional support to the crown, 
 and at the same time, serving to strengthen the root and overcome 
 the liability of fracture (Fig. 315). 
 
 The crowns used for this purpose may be any of the numerous 
 varieties which are made by the different manufacturers, even to 
 the diatoric teeth which are made for vulcanite work. The crown 
 selected is ground to conform to the size and shape of the root, 
 and to touch it only at the labial side, leaving plenty of room between 
 the face of the root and the crown to allow of a heavy base, as in 
 Fig. 316. 
 
 The post, or pin, which is preferably made of iridio-platinum 
 or platinized gold wire, is then adjusted, and should be of sufficient 
 length to go nearly or quite to the bottom of the hole in the base 
 of the crown and into the root to a depth at least equal to the length 
 of the crown (Fig. 316). It is well to first flow a little sticky wax 
 around the post, between the base of the crown and the face of the 
 root, at point a in Fig. 316, as the wax, of which the base is to be 
 made, will adhere to the post better than it would otherwise. 
 
 The base of the crown should be moist or be lightly oiled or 
 coated very thinly with cocoa-butter to prevent the wax from 
 adhering to it, and the base wax, which should be a little softer 
 and tougher than the ordinary inlay wax, is softened and pressed 
 around the pin at the base of the crown, which is forced on the 
 
CASTING PROCESS IN CROWN WORK 
 
 201 
 
 root and carefully adjusted in position. After the wax has been 
 chilled, the surplus should be carefully trimmed, until it is per- 
 fectly smooth and flush with the sides of the crown and root 
 (Fig. 317). The crown, together with the pin, is then removed 
 from the root and the sprue wire attached, or it may be attached 
 in the mouth as in Fig. 317, by heating it just sufficient to imbed 
 it slightly in the wax. It may be more firmly fixed by flowing 
 
 Fig. 315 
 
 Fig. 31G 
 
 Fig. 317 
 
 a very small amount of wax around it at the point of entrance, 
 after which the crown has been removed. 
 
 The sprue wire is now placed in the base of the flask (Fig. 318) 
 and the crown base is invested in the same manner as an inlay, 
 painting the investment on very carefully so that there may be 
 no air bubbles, which would be reproduced in gold in the casting 
 and interfere with the fit of the base. After casting, it is cleansed 
 
 Fig. 318 
 
 and polished and adjusted to the crown and root. The base is 
 first cemented to the crown and after the cement has thoroughly 
 hardened, it is cemented in the mouth. 
 
 This makes a satisfactory crown when used singly, but it is not 
 suitable for a bridge, as all bridge abutments should be banded. 
 
 Banded Crowns.^ — The caps for these crowns can be made in the 
 same nianncr as for a Richmond crown, being carried well beneath 
 
202 THE MAKING OF THE CROWNS 
 
 the gum labially. The impression is taken and the model prepared 
 in the usual way. 
 
 The crown is ground in the manner already described in treat- 
 ing of a crown with a cast base, being beveled lingually and on 
 the mesial and distal sides about half or two-thirds of the way to 
 the labial face (Fig. 319). This allows a sort of a socket for the 
 crown to set in, and, at the same time, insures the correct position 
 of the crown on the base. 
 
 The base of the crown is lubricated, so that the wax will not 
 stick to it, and the wax flowed in between the crown and the cap, 
 until it is well filled, after which it is carved flush with the crown 
 and the band and the sprue wire attached, as in Fig. 320. The 
 crown is now removed, leaving a wax base attached, as in Fig. 321. 
 It is then set in the flask base and invested and cast in the usual 
 manner. The base should be polished with the crown in position, 
 
 Fig. 319 Fig. 320 Fig. 321 
 
 after which the crown is cemented to the base and kept under 
 pressure until the cement has hardened. It will then be ready 
 for the mouth. 
 
 This method of procedure may be followed in making any crown 
 of this type from molars to incisors. 
 
 Casting Base for Crown with Porcelain Facings. — In crowns of 
 the Richmond type, where a porcelain facing is used, the cap and 
 pin are made and fitted to the root, and the facing ground to place 
 sloping it slightly more than the floor, so as to allow the wax to 
 flow under the facing (Fig. 322). If there has been much recession 
 of the gum, so that the band has to be sloped greatly labially (Fig. 
 323), it is well to grind a step in the bottom of the facing, in order 
 that there may be a good base for it to rest on, thereby rendering 
 it less hable to be forced down the incline and fractured (Figs. 323 
 and 324). The facing should then be lubricated on the lingual 
 side, and held in place with a little sticky wax on the labial side, 
 
CASTING PROCESS IN CROWN WORK 
 
 203 
 
 or a light wall of plaster or modeling composition. The lingual 
 side should be built up with hard inlay wax and carefully carved 
 and smoothed (P'ig. 325). It should be remembered that the more 
 carefully the crown is finished in the wax, the easier it 
 will be to finish the completed crown. 
 
 The sprue wire is attached, as shown in Fig. 325 the 
 facing carefully removed and small pins of graphite 
 inserted in the holes left by the tooth-pins, leaving 
 them long so as to be gripped in the investment (Fig. 
 326). 
 
 Another method is to enlarge the pin-holes in the 
 wax after removing the facings and dovetail them on 
 the inside, as in Figs. 327 and 328. This can be readily 
 done with a small coarse bur. It is then invested, care being 
 taken to fill with the investment if the pin-holes have been enlarged. 
 
 Fig. 322 
 
 Fig. 323 
 
 Fig. 324 
 
 Fig. 325 
 
 1^ 
 
 Fig. 326 
 
 If graphite pins have been used, after the casting has been made, 
 they are removed, the sides of the holes roughened, and the piece 
 cleansed and polished. The tooth-pins are then lightly threaded 
 
 Fig. 327 
 
 Fig. 32« 
 
 or roughened and the facing cemented in j)lace. If the holes 
 were enlarged and dovetailed, the pins may be flattened a little 
 and then bent at right angles, as shown in Fig. 329, and cemented 
 in place. 
 
204 THE MAKING OF THE CROWNS 
 
 Casting Directly on the Facings. J-In making a single crown or a 
 small bridge, where it is intended to cast directly against the 
 facings, great care should be taken that the wax does not overlap 
 the porcelain at any point. This is of the utmost importance, 
 for should the wax be extended so as to grip the facings when the 
 casting is made, the contraction of the metal on cooling will be 
 certain to crush them. The wax should be carefully trimmed to 
 the edges of the porcelain, and it is a good plan to clean them well 
 by rubbing the edges with a piece of tape or cloth before investing. 
 
 Drying out and Heating up the Flask. — The flask should be dried 
 out carefully and then brought to a very high heat throughout so 
 that the facing will be red hot when the gold comes in contact with 
 it. If the facing is cold, or but slightly heated, when the casting 
 takes place, the rapid expansion of the platinum pins, taking the 
 heat so much more quickly than does the porcelain, will fracture 
 the facing. After casting, the flask should be allowed to become 
 cold before opening, after which the piece is cleansed and is ready 
 for finishing. 
 
 The crown, or the bridge, which has been made in this way will 
 be satisfactory, providing there is little or no strain on the facings, 
 but otherwise the method is decidedly objectionable. 
 
 In a facing which is reheated, in soldering or otherwise, the 
 strength of the porcelain is diminished, and especially is this the 
 case if a mass of gold is forced upon it in a molten state. The 
 piece may come out with the facings seemingly intact, but they 
 have been weakened and in the majority of cases, if examined under 
 a microscope, will show innumerable fine checks running all through 
 them. If it is possible to avoid it, it is far better not to subject 
 the facings to this refiring, as they are thereby rendered much 
 less serviceable than they otherwise would be. 
 
CHAPTER XI. 
 BRIDGE-WORK. 
 
 A DENTAL bridge consists of a continuous masticating surface, 
 or of a succession of crowns or dummies having incisal edges. As 
 fts name implies, it is a bridge proper, depending for its retention 
 and support upon the natural teeth or roots in the mouth, which 
 serve as abutments. The success and the permanence of the device, 
 in this, as in the case of any other form of a bridge, depends 
 entirely upon the number, position and condition of the abutments. 
 
 The primary object of bridge-work has been, and is, to do away 
 with the inconveniences associated with a plate, and to give patients 
 an appliance which through its firmness and immobility will enable 
 them to perform the masticatory function more perfectly than can 
 possibly be done with a plate. 
 
 The natural teeth or roots supporting a bridge are called the 
 abutments, and the intervening portions are known as the body of 
 the bridge. The body of the bridge is made up of one or more 
 pieces representing the different teeth and these are known as 
 dummies. 
 
 The idea of bridge-work is not new. We fine many traces, even 
 among the ancients, of attempts to restore lost teeth. These early 
 efforts were confined almost exclusively to fastening together with 
 wire the crowns of natural teeth, and these in turn were bound to 
 the remaining teeth in the mouth by wires. These restorations 
 were entirely for esthetic purposes, and were of no practical value 
 to the wearer for mastication. 
 
 Modern bridge-work is of comparatively recent date, and it is 
 only within the past thirty or thirty-five years that it has been 
 put to really practical use, and today it is recognized as being an 
 important specialty of the dental profession. There is no form of 
 denture made which so nearly approaches nature in the restoration 
 of the normal function of the lost organs. 
 
 CLASSIFICATION OF BRIDGES. 
 
 Dental bridges arc divided into two primary classes, fixed and 
 removable. 
 
206 BRIDGE-WORK 
 
 Fixed bridges are those which are attached to the abutments so 
 that it is impossible for the patient to remove them, or even the 
 dentist, without more or less mutilation of the abutment crowns. 
 
 Removable bridges are those which can be removed from the 
 mouth by the patient for cleansing of other purposes, without 
 interfering with or disturbing the stability or integrity of the 
 appliance. 
 
 The insertion of dental bridge-work requires the mutilation of 
 the teeth, serving as abutments, to a greater or less extent, and in 
 nearly every case the pulp must be sacrificed. This was at first 
 considered as one of the great objections to bridge- work, but it 
 was simply a case of sacrificing one for the good of many. If the 
 work was properly done, it was found that this sacrifice was justified 
 in the increased comfort and improved health of the patient. 
 
 The value of bridge-work is unquestionable. This value depends 
 entirely upon the manner in which the work is done, and where 
 it is used and not abused, there is nothing that can take its place. 
 
 Bridge-work is not universal in its application, and is not intended 
 to do away with other forms of denture, but it is unquestionable 
 that in a large number of cases where partial plates are being placed 
 in the mouth, that they are in reality an injury, rather than a 
 benefit of the patient, and bridge-work is positively indicated and 
 would render far greater service than is possible with the dentures, 
 which are given them. 
 
 REQUISITES OF A DENTAL BRIDGE. 
 
 The first requisite of a dental bridge is that it should restore 
 as nearly as possible the lost functions and appearance of the 
 teeth which have been lost. Esthetic conditions are too frequently 
 lost sight of in this work, but they are as important in this as in 
 any prosthetic operation, and as much attention should be paid 
 to esthetic effect as can be safely done without sacrificing the 
 utility of the piece. 
 
 The crowns or facings which are to be used should be carefully 
 selected, with due regard to their proper sizes, shapes, texture and 
 colors. The occlusal surfaces should be made so that they shall 
 effectively perform the work of mastication, and at the same time 
 with no undue strain on the abutments. 
 
 Every portion of the bridge should be made with the idea of 
 accessibility to the bristles of the toothbrush in cleansing, so that 
 
THE PREPARATION OF ABUTMENTS 
 
 207 
 
 it may be kept as free as possible from foodstuffs and other debris. 
 Spaces between the facings themselves, or between the facings and 
 the abutments in bridges restoring teeth in the posterior part of 
 the mouth should be partially filled with gold so as to offer as little 
 lodgment for foreign substances as possible. Unnecessary exposure 
 of gold is always to be avoided, and never in any bridge, placed 
 anterior to the bicuspids, should gold be shown. 
 
 THE PREPARATION OF ABUTMENTS. 
 
 The first and most important consideration in preparing for the 
 insertion of a bridge is the condition of the abutments. The direc- 
 tions given in Chapters IV-VI on the treatment and the preparation 
 
 Fig. 330 
 
 Fig. 331 
 
 of the roots and the perfect adaptation of the bands to the stump 
 or roots will apply with far greater force when these roots are to 
 serve as abutments for a bridge. 
 
 Paralleling the Abutments. — Regarding the mutual relation of the 
 individual abutments, they must be made parallel, or very nearly so, 
 especially where there are more than two. As previously stated, 
 there is a slight natural movement to the roots of which advantage 
 can be taken to help hold the bridge firmly in position, and the 
 abutments may be very slightly converging or diverging, so that 
 there will necessarily be a slight spring to them in placing the 
 bridge in the mouth; but this movement must be very slight, 
 otherwise it would result in the loosening of the teeth. 
 
 In i^aralieling a series of abutments, the start should always 
 
208 
 
 BRIDGE-WORK 
 
 be made with the smallest and the others paralleled to that one, 
 especially if this small abutment is an anterior root in which a pin 
 or tube is to be used. The object of doing this can readily be seen 
 by studying the illustration. If one of the abutments is a lateral 
 incisor and another a cuspid or a tooth on which is to be placed a 
 shell or telescope crown, the lateral being a very small root allows 
 very little leaway in placing the post or tube, as the canal must 
 necessarily be enlarged on its original line. If a cuspid is used as 
 another anchorage, the root is of sufficient size so that the canal 
 can easily be sloped to one side or another to make it parallel with 
 the lateral abutment, as shown in Fig. 330. Should one of the 
 other abutments be a shell crown, the stump can readily be ground 
 on one side or another to make it parallel with the lateral or 
 bicuspid abutment (Fig. 331). 
 
 Fig. 332 
 
 THE WEINSTEIN PARALLELING DEVICE. 
 
 Mr. L. J. Weinstein's paralleling device is essentially practical. 
 The mechanical construction is very simple and it combines ease 
 of manipulation with perfect accuracy. Its range of adaptability 
 is far greater than anything else available up to the present time. 
 The device consists of an arch of steel, perforated at intervals as 
 shown in the illustration (Fig. 332). In these holes are fitted 
 studs, held in place with collar, and nut with spring giving constant 
 tension. Through the square opening in the top of this stud is 
 
THE WEINSTEIN PARALLELING DEVICE 
 
 209 
 
 passed a hollow square bar with a V cut in- one end. Through 
 this bar is passed a round rod with a hole in one end to receive the 
 mandrel, the other end being threaded to receive a knurled nut. 
 
 The mandrel is placed in the hole in the rod and the nut tightened, 
 drawing it into the Veed end of the hollow bar and holding it per- 
 
 FiG. 333 
 
 ^Kd^ 
 
 ■ 
 
 ^ 
 
 fM 
 
 1 
 
 n 
 
 Im 
 
 ^^^^B^^^^^BBfcBtt;T!/v 
 
 ^^ 
 
 g^^gs^^HH^H 
 
 Fig. 334 
 
 fectly rigid. This bar can be nio\cd horizontally in any direction 
 and locked in place by tightening the nut on the stud on the 
 underside of the arch. The device will accommodate any required 
 numlx-r of the mandrel holding rods and several abutments can 
 be paralleled simultaneously. The caj)s can be placed on the 
 14 
 
210 
 
 BRIDGE-WORK 
 
 roots, the tubes on the mandrels and after entering them in the 
 canals they can be waxed to the caps, removed and soldered. 
 
 Another method is, after placing the tubes in position, to take 
 an impression, covering the ridge, caps and mandrels with plaster. 
 After the plaster has hardened, the impression is removed from 
 the mouth, with the caps and tubes in place, as shown in Figs. 
 333 and 334. The impression is removed from the paralleling 
 device by loosening the nuts at the end of the square rods and 
 withdrawing the mandrels from the holders. The caps and tubes 
 are then waxed from the under side in the manner already described, 
 the impression varnished and a model prepared, and the waxing 
 
 Fig. 335 
 
 of the tubes to the caps is done on this model. The caps and 
 tubes are then removed, invested and soldered. 
 
 Fig. 335 shows the manner of paralleling posterior abutments 
 to an anterior abutment, either in the mouth or on the model. 
 The mandrel is fitted in the tube in cuspid root and locked to the 
 arch. Another mandrel is locked tightly in a holder distally but 
 the nut locking the bar to the arch is tightened only enough to 
 hold the mandrel holder in proper position so as to allow of easy 
 movement in a horizontal direction. The mandrel in the cuspid 
 tube rotating freely, allows the other mandrel to move freely to 
 any point so that the molar or bicuspid caps are easily adjusted. 
 
OCCLUSION 
 
 211 
 
 The paralleling device outfit consists of two arches (sn:all and 
 large) and the necessary mandrel holders, a gauge for quickly 
 neasuring the diameter of mandrels or tubes and a number of 
 non-nisfing mandrels, one-half to one-thousandth of an inch smaller 
 than the hardened steel m.andrels o^•er which the platinum tubes 
 fit snugly. These mandrels are very useful as they will not rust 
 from contact with saliva, or when being exposed to the air, and 
 being just a trifle sm.aller, go in and out of the tubes easily, whereas, 
 the hardened steel mandrels, over which the tubes are made or 
 drawn, must, of necessity, fit quite snugly. 
 
 All the parts of the paralleling device are rust-proof so that it 
 is not aft'ected bv moisture. 
 
 Fig. ."536. — Upper and lower teeth in occlusion. (From photoKniph of 
 specimen in the Wistar Institute of Anatomy.) 
 
 OCCLUSION. 
 
 In addition to its other rccpiircmcnt. the occlusion of a bridge 
 piece must be as nearly jjerfect as it is possible to make it. This is 
 a most important consideration and one to which too little atten- 
 tion is generally given. A bridge which properly occludes with 
 the ofjpositig teeth will not only be more effective than one faulty 
 in this resijcct, but its nse will be attended with liir less liability 
 of loosening or injuring of the iibiitnients. 
 
212 
 
 BRIDGE-WORK 
 
 A large percentage of the cases of bridge-work are for the posterior 
 part of the mouth, the dentist being most frequently called upon • 
 
 Fig. 337. — Occlusion of the incisor teeth. (From photograph of specimen 
 No. 4237, Wistar Institute of Anatomy.) 
 
 Fig. 338. — Occlusion of the molar and bicuspid teeth, external view. (From 
 photograph of specimen in possession of the author.) 
 
 to restore lost molars and bicuspids. Where these teeth in either 
 jaw have been lost for any length of time, their antagonists in the 
 
OCCLUSION 
 
 213 
 
 opposite jaw are sure to have elongated to a greater or less extent 
 (Fig. 340), and if no measure is undertaken to prevent it, they will 
 eventuallv be exfoliated. The normal line of occlusion must be 
 
 Fig. 339. — Occlusion of the molar and bicuspid teeth, internal view. (From 
 photograph of specimen in possession of the author. Same specimen as Fig. 338.) 
 
 restored in such cases, if a satisfactory denture is to be made to 
 replace the lost teeth, whether it be a i)late or a bridge. If a bridge 
 
 Vu;. 340 
 
 Fk;. 341 
 
 is constructed without doing this, it can nc\cr be as scr\iceablc to 
 the patient as where the occlusion has been made normal. The 
 triturating motion, so necessary for the perfect pcrforniiiiice of the 
 
214 BRIDGE-WORK 
 
 masticatory function, is interfered with or altogether lost, the only 
 movements possible being the opening and closing of the jaws, in 
 which case the food may be pressed or crushed, but not ground. 
 The moment the mandible is thrust the least bit forward, the jaws 
 are thrown apart and the only point of contact is the distal cusp 
 of the elongated molar, with the mesial cusp of the lower molar 
 opposite (Fig. 341). 
 
 Where this elongation of the teeth has taken place, they must 
 be ground to the normal line of occlusion and the teeth carved so 
 as to reproduce, as nearly as possible, the original cusps. If they 
 have become very much elongated, it may be necessary to devitalize 
 and crown them, or to restore their masticating surfaces by building 
 up with gold or porcelain. 
 
 SELECTION OF FACINGS. 
 
 In choosing facings or crowns for a crown or a bridge, or in fact 
 for any form of partial denture, the greatest care should be exer- 
 cised to select those of proper mold and shade. If it is impossible 
 to get a facing to match exactly, it is better that it should be slightly 
 darker in shade rather than lighter than that of the natural teeth. 
 If a crown is the least particle too light in color it is conspicuous, 
 and is the first tooth seen when the patient opens the mouth, while 
 if it is but slightly darker than the neighboring teeth it is not so 
 noticeable. 
 
 In restoring the six anterior teeth, the facings should not be 
 bought in sets as put up by the manufacturers. In the human 
 mouth, these teeth are never all of the same shade. The central 
 incisors have generally a yellowish cast. The laterals are of the 
 same general shade but are clearer at the tip with a slight bluish 
 tint, while the cuspids are the yellowest teeth in the mouth anterior 
 to the molars. If the facings, restoring these teeth, are all of one 
 color, they will not present a natural appearance, since their 
 uniformity of color will at once advertise their artificial nature. 
 They should be selected in pairs, the centrals, lateral and cuspids, 
 each from a different set in accordance with the natural shading 
 of these teeth, but the blending should be perfect. 
 
 As we go farther back in the mouth we find the bicuspids are 
 more on the order of the lateral incisors, being clearer at the tips 
 and of a slightly bluish tint, while the molars are generally yellow. 
 In selecting these teeth, the bicuspids, especially the first, should 
 
FIXED BRIDGES 
 
 215 
 
 be matched as nearly as possible. With the molars there is not 
 the same necessity for being so exact. They should be of the 
 same general shade and blend well, but may be darker than the 
 natural teeth, but in no case should they be lighter. 
 
 The shapes of the teeth also should be studied carefully, and the 
 form of those lost should be reproduced as nearly as possible by 
 their substitutes. The types of teeth vary greatly, some having a 
 broad flat face, others being very much rounded (Figs. 342 and 
 343). Again, it will be found that some are nearly flat from the 
 
 Fig. .342 
 
 Fig. 343 
 
 Fig. 344 
 
 Fig. 345 
 
 incisal edge to the gingiva while others are decidedly convex, as 
 in Figs. 344 and 345. Where one of these types prevail a corre- 
 sponding tooth to replace it or its mate should always be selected. 
 The remaining natural teeth will serve as an index for the form 
 i)f the selected crowns or facings. 
 
 FIXED BRIDGES. 
 
 In considering the construction of a fixed bridge, as a common 
 type, one which might be called a skeleton bridge will be selected, 
 one in which two full gold crowns or a full gold crown and a porce- 
 lain-faced crown are to serve as abutments, carrying one or more 
 dummies, the occlusal and lingual surfaces being of gold, and using 
 porcelain veneers simply for esthetic effect (Figs. 34() and 347). 
 
 I..- 
 
 Fi(i. 340 
 
 Fig. 347 
 
 The bands or caps having been adjusted in their resi)ective 
 positions in the mouth, the impression and articulation are taken, 
 and the model is preparerl in the maimer already described. The 
 shell crowns are c()mi)lct('d aixl articulated aii<l are then ready for 
 the facint:s. 
 
216 
 
 BRIDGE-WORK 
 
 In selecting the facings for the case, it is desirable to choose 
 them of such length that when they are ground into place, the necks 
 will touch the gum lightly and the occlusal edges will be in contact 
 with the antagonizing teeth (Fig. 348). They are ground to follow 
 the gum line and should set very close to each other, but should 
 not be in actual contact (Fig. 347). After they have been ground 
 into place, a wall of plaster is built-up on the buccal side of the 
 model, nearly to the occlusal or incisal ends of the facings, to retain 
 them in position (Fig. 348) . 
 
 Fig. 348 
 
 Fig. 349 
 
 After the plaster has hardened, the facings are removed, and 
 their occlusal ends ground off about one thirty-second of an inch 
 and at an angle of about forty-five degrees with the back of the 
 facing (Fig. 349). The line of their occlusal ends should be con- 
 tinuous, that is, the bevel of one facing should not be higher than 
 another. 
 
 The facings are then backed, and for this purpose, platinum, 
 crown metal or pure gold may be used. The gold will have a ten- 
 dency to lighten the color of the facing and give it a slightly yellower 
 
 Fig. 350 
 
 Fig. 351 
 
 cast, while the platinum will tend to darken it and confer a bluish 
 tint. If the backing is of platinum or crown metal, it may be very 
 thin, about three one-thousandths of an inch. It should extend from 
 the inner edge of the bevel at the occlusal end, to about one-sixteenth 
 of an inch beyond the lower edge where it has been ground to fit the 
 
FIXED BRIDGES 
 
 21: 
 
 gum (Fig. 350) . The backing of each facing should touch or sUghtly 
 o\erlap that of the one next adjoining and those of the end facings 
 should be in contact with the abutment crowns (Fig. 351). 
 
 The pins are flattened with a pair of pin-roughing pliers, and are 
 bent down over the backing, thus pressing it close to the facing. 
 The facings are then waxed together and to the abutment crowns 
 with hard adhesive wax, a piece of oiled-paper being placed under- 
 
 FiG. 352 
 
 Fig. 3.53 
 
 neath on the surface of the cast to prevent the wax from adhering 
 to it. The wax should be built up high enough to support the 
 cusps for the dummies (Fig. 352). Suitable solid cusps are then 
 made, ground or filed to fit the bevel of the facings, and fastened 
 in place with adhesive wax (Fig. 353). • 
 
 The bridge is now ready for investing and soldering. It is taken 
 from the model, and the inside of the abutment pieces filled with 
 the investing material and the whole bridge partly imbedded in 
 it with the facings down. The investment should come over the 
 backings which extend beyond the lower angle of the facings, hold- 
 ing them in place and preventing their springing up under heat 
 (Fig. 354, a), and nearly to the lingual edge of the cusp (Fig. 354, h) 
 
 
 Fig. 3.'>6 
 
 Fig. 3.54 
 
 Fig. 355 
 
 Fig. 357 
 
 and should be small, large enough only to hold the parts securely 
 together. The abutment crowns are partly covca-ed to protect 
 them horn the Hame. 
 
 In grinding the facings of the dummies for an>- of the six anterior 
 teeth, they should be made to set closely to the model, and after 
 they are properly fitted a wall of plaster is made 011 the labial side. 
 
218 BRIDGE-WORK 
 
 The facings are then backed, the backings extending over the 
 beveled portion at the neck and about one-sixteenth of an inch 
 beyond the incisal edge and the pins flattened and bent toward this 
 edge close to the backing (Fig. 355). In investing, the investment 
 should cover the extending portions of the backing, both at the 
 incisal and gingival ends, to prevent its warping (Fig. 356). 
 
 After investing, a wire of coin gold should be fitted to, and laid 
 over, the backings at the gingival edge as shown in Fig. 357, so that 
 in soldering, the lingual side may be built up more nearly to the 
 normal contour of the tooth. 
 
 Bridges of three or four teeth may be soldered in one piece, but 
 large cases should be soldered in sections, because the contraction 
 of large masses of solder, when the piece is cooling, has the effect 
 of disturbing the relation of the abutment pieces, and in conse- 
 quence the fit of the bridge is impaired. A full bridge of twelve or 
 fourteen teeth should be soldered in three or four sections. If in 
 three, the incisors may be soldered in one piece, and the sides, 
 from the cuspids back, separately. If in four sections, the central, 
 lateral and cuspid of each side may be soldered separately, and 
 also each side sections. 
 
 The different sections are finished and polished except where 
 they are to be united. They are then replaced on the model, waxed 
 together with adhesive wax, and a strong iron or brass wire bent 
 to conform to the lingual side of the bridge and thoroughly waxed 
 to the different parts. This will hold them firmly in their relative 
 positions, and prevent their springing while being removed from 
 the model and invested. The bridge is then invested, the divisions 
 between the several sections being freely exposed and the parts 
 united with the same, or a slightly lower carat solder than has been 
 used in the previous soldering. When the investment has cooled, 
 the bridge is removed, pickled in dilute sulphuric acid, and finished. 
 
 Interchangeable Facings. — In using interchangeable facings of the 
 Steele or Evslin type (Figs. 354 and 355), the facings are ground in 
 as are the ordinarj^ pin-facings, and afterward a wall of plaster is 
 built around them, reaching nearly to the incisal edges. The back- 
 ings are then fitted and should be carried a little beyond the incisal 
 edge. The backings should be made so that they will come in 
 contact with each other, after which they are waxed firmly together 
 with hard, sticky wax, a heavy iron or brass wire being laid across 
 the lingual side of the backings to prevent their becoming distorted 
 in removing the facings and investing. 
 
PIXED BRIDGES 
 
 219 
 
 After the facings are removed, it is well to give the labial side 
 of the backings a coating of anti-flux (whiting may be used for this 
 purpose) before investing. This will tend to prevent any solder 
 from flowing on that side of the backings. 
 
 Fig. 35S 
 
 Fig. 359 
 
 
 Fig. 360 
 
 They are then invested, labial face down, and should lay nearly 
 level. After the wax has been removed a heavy gold wire, prefer- 
 ably square, should be fitted along the gingival 
 edge of the backings, as in Fig. 360, and the piece 
 heated up for soldering. Twenty or twenty-one 
 carat solder should be used for soldering, and 
 the solder built up so as to restore as nearly as 
 possible the normal lingual surfaces of the teeth, 
 leaving it thick at the incisal edge. It will be found that the 
 wire across the base of the backings will very materially aid in 
 giving form to the backs. The piece is then cleansed and finished. 
 In finishing a bridge of this character, it is well to outline and 
 contour the lingual surfaces of each tooth restored so that they 
 will resemble the lingual surfaces of the natural teeth as nearly as 
 possible and j)resent a more artistic efl'ect, and consefjuently a 
 much more comfortable feeling to the tongue. 
 
 In finishing the incisal edges of the backings, the facings should 
 first ])v replaced and then the backings ground from the labial 
 side flush with the facings at that point and extend- 
 ing a little upward on the lingual side, as in Fig. 
 'MW , so that the backing will be a little longer at 
 this j)()int and will protect the facings. The gold 
 should be left as thick as the bite will allow at 
 Fig. :mi the incisal edge so as to protect the facings and 
 
 lessen the liability of their being broken. Such 
 facings are nnich weaker than are the ordinary pin-facings, and for 
 this reason, it is always best to prepare duplieates which may be 
 
2'20 BRIDGE-WORK 
 
 used in case of an accident. In any event, the shades and mold of 
 the crowns or facings used should be placed on record. In grinding 
 in the duphcates, whether crowns or facings, they should be made 
 very exact so that if it were necessary to replace one, the duplicate 
 could not be told from the original. Each crown should be ground 
 separately, with all of the others in position. 
 
 If duphcates are to be made of the six anterior teeth, they should 
 be taken one at a time, removing the cuspid first and grinding in 
 the duphcate cuspid so that it exactly corresponds with the original. 
 After this has been completed, the original cuspid is replaced and 
 the lateral removed and the duplicate lateral ground in, After 
 which the original lateral is replaced and the central removed and 
 the new one ground in place and so on until duplicates of the 
 entire set have been made. 
 
 In this way as many duplicates as may be desired can be made 
 with the knowledge that they are all absolutely interchangeable. 
 This same order should be followed whether facings or crowns 
 are being used. 
 
 EXTENSION BRIDGES. 
 
 In a very large majority of the smaller extension bridges which 
 are made, where the whole or a portion of the body of the bridge 
 extends beyond the single abutment, as in Figs. 362 and 363, the 
 entire principle -is faulty and the whole piece a mechanical impos- 
 sibility. Notwithstanding this, pieces of this description are placed 
 in mouths to the detriment of the patients. Sooner or later the 
 
 Fig. 362 Fig. 363 Fig. 364 
 
 abutments to which these pieces are anchored are sure to be forced 
 out of their normal position and frequently are lost. In the 
 anterior part of the mouth, where an appliance, such as shown' in 
 Fig. 363 has been inserted, the rotation and consequent loosening 
 of the root is inevitable. 
 
 In Fig. 364, where a dummy having an occlusal surface is attached 
 to a single abutment there is not only a strong lateral strain which 
 
THE USE OF PORCELAIN CROWNS IN BRIDGE-WORK 221 
 
 will give a constant twisting motion to the root, but there is also 
 a direct force which is being continually exerted, gradually tilting 
 the abutment and forcing the dummy into the tissues (Fig. 364) 
 with the resultant loss of occlusion and the eventual loss of the 
 tooth to which the bridge is attached. 
 
 One inflexible rule applies in all of these cases and that is that 
 there must always be a support at each end of a bridfje and never 
 under any consideration should a single point (f attachment be 
 depended upon to carry a dummy. 
 
 A small spur of platinized gold or iridio-platinum, attached 
 to the lingual side of the dummy, and resting in a small gold filling 
 or inlay on the lingual side of an adjoining tooth, as shown in Fig. 
 365, will entirely overcome the possibility of rotation, and will 
 make the piece a permanent fixture rather than a temporary one. 
 
 Fig. 365 Fig. 360 
 
 A spur resting in the lingual side of the cuspid or in a filling or 
 inlay in the fissure of a molar or bicuspid (Fig. 366), will effectu- 
 ally prevent future trouble and render a piece serviceable which 
 would otherwise be worthless. 
 
 Extension Bridges with Saddles. — Extension bridges, in which 
 saddles, resting on the ridge, are employed as an additional sui)port 
 should never be used in fixed bridges, as it is impossible to properly 
 cleanse an appliance of this kind. Irritation and inflammation 
 are sure to ensue, and its use will sooner or later result in the loss 
 of the abutment teeth, if not in troubles of a more serious nature. 
 
 THE USE OF PORCELAIN CROWNS WITH SOLDERED BASE IN 
 FIXED BRIDGE WORK. 
 
 Where porcelain crowns are used in fixed bridge-work, there 
 must be a deptli of bite great enough to allow a sufficient mass of 
 metal beneath the crowns to give strength and stability to the 
 appliance, and at the same time allow of space enough on the 
 lingual side between the base and the gum to permit of properly 
 cleansing the piece. In any of the six anterior teeth, unless there 
 
222 BRIDGE-WORK 
 
 has been a great resorption of tissue, the dummy crowns should be 
 ground so that they will rest on the gum at the labial side, but be 
 freely clear of the gum on the lingual, as in Fig. 367a. 
 
 After the crowns have been properly ground and arranged on 
 the model, a wall of plaster should be built up on the labial side 
 so as to retain them in position (Fig. 367 b). The lingual side and 
 
 Fig. 367 Fig. 368 Fig. 369 
 
 on the mesial and distal about half or two -thirds the way to the 
 labial should be beveled in order that the bases may come up over 
 the edges of the crowns at these points and form a positive seat in 
 which the crowns may rest (Fig. 368). They should all be ground 
 symmetrically and on line one with another so that one will not 
 stand conspicuously above its mates. 
 
 The foregoing will apply to the preparation of crowns for the 
 posterior part of the mouth when the depth of the bite is not too 
 great. 
 
 The bases for the crowns of pure gold, No. 35 or 36 guage, are 
 first made. These may be fitted by swaging or burnishing, the 
 gold extending up over the beveled edges of the crowns. Openings 
 are made through the floors of the bases and through these openings 
 posts of platinized gold are fitted. These are then waxed, removed, 
 invested, and the posts soldered to the bases from the under side 
 with a little piece of coin gold (Fig. 369). They are then replaced 
 on the crowns, properly assembled on the model and waxed firmly 
 together. It is a good plan to lay a piece of heavy iron or brass 
 wire across the bases and wax it firmly to prevent their changing 
 position while investing. The crowns are then removed and the 
 bases invested,- leaving the under surface well exposed. It will 
 assist materially in soldering, if a small wire of coin gold is placed 
 
THE USE OF PORCELAIN CROWNS IN BRIDGE-WORK 223 
 
 throughout the length of the piece on the Hngual iside and the 
 solder built up to that (Fig. 370). 
 
 Fig. 370 Fic. 371 
 
 After soldering, the piece is cleansed in acid, polished and finished, 
 except at the points where it is to be united to the abutment caps 
 (Fig. 371 ). The crowns are then put in place on their bases and care- 
 fully adjusted on the model, and the bases waxed carefully to the 
 abutment caps. The crowns are then removed and the abutment 
 caps, together with the crown bases, are invested and united with 20- 
 or 21-carat solder. After the piece has been cleansed and polished, 
 it is ready for the cementing of the crowns. The pin holes in the 
 crowns are filled with cement, as are the bases, and the crowns 
 are forced into place and kept under pressure until the cement has 
 well hardened, after which the excess of cement is trimmed away 
 and the l)ridgc is ready for the mouth. 
 
 Use of the Cast Base. — If the bases are to be cast, posts of plat- 
 inized gold may be fitted into the post-holes in the crowns, or the 
 posts may be made at the same time the base is cast, by forcing 
 a small, pointed piece of inlay wax in the hole in the base of the 
 crown and this being united with the wax base becomes a part of 
 the casting. The bases of the crown should be lubricated with 
 cocoa butter or glycerin, and a piece of tin foil or oiled paper 
 fitted over the ridge to protect the model from the wax and permit 
 of their easy removal, and the space between the crowns and the 
 paper filled in with inlay wax, after which it is removed and carved, 
 cutting awa\' enough of the wax on the under side lingually so 
 that it will clear the gum sufficiently for cleansing i)urposes. 
 
 The crowns should be removed and replaced several times to 
 make sure that they are perfectly free. 
 
 If there should be not more than two or three bases to be made 
 they may be cast in one piece. If the four incisors are to be restored 
 it is better to divide the base at the median line and cast the two 
 halves separately, afterward uniting them with solder. 
 
 The sprue wire is firmly attached to the lingual side, and this 
 should be done before fiFially removing the crowns, so that there 
 
224 BRIDGE-WORK 
 
 is no likelihood of distorting the wax on the inside of the base 
 (Fig. 372). 
 
 In the posterior part of the mouth, where the gold is not likely 
 to show, the bases may be carried through to the buccal side, and 
 
 Fig. 372 Fig. 373 
 
 in such cases the base of the crowns are beveled slightly all around 
 so that they may be firmly seated. They should be cut high on the 
 lingual side, the same as the anterior crowns, for cleansing purposes 
 
 (Fig. 373). 
 
CHAPTER XII. 
 REMOVABLE BRIDGE-WORK. 
 
 WiiH the advent of removable appliances, the possibilities of 
 bridge-work have been greatly increased. The field of operations 
 has been extended so as to include, not only many cases where 
 fixed bridges have been worn, but also a great many others where, 
 up to that time, the only hope of the patient was a plate, more or 
 less satisfactory. 
 
 The advantages of removable bridge-work o\er fixed bridges 
 are many, and it is very questionable whether there is a single 
 instance where fixed bridge-work answers the purpose better than 
 removable. It is undoubtedly true that in almost every case where 
 fixed bridge-work has been placed, removable bridge-work could 
 have been used to a much better advantage and would have given 
 far greater satisfaction to the patient. Then again, there are many 
 cases where conditions are such that a removable bridge is indicated, 
 where a fixed bridge should not be thought of. 
 
 From a hygenic point of view, there can be no question as to 
 which is the best. A removable piece can be taken from the mouth 
 and thoroughly cleansed and sterilized by boiling or any other 
 method which the patient may desire. When the bridge has been 
 removed, the abutment caps, being i)erfectly simple and easily 
 accesible, can be thoroughly cleansed at every point. 
 
 In the case of. a bridge which is immovably fixed to its supports, 
 there are spaces and crevices in which particles of foodstufi" or 
 other material may lodge, which cannot be reached even by the 
 dentist. It is impossible to thoroughly- cleanse and sterilize such 
 a briflge, as there is nothing which can be taken in the mouth that 
 is of sufficient strength to perfectly cleanse and sterilize it without 
 injury to the soft tissues. 
 
 Another advantage, which a removable bridge j)ossesses over 
 a fixed bridge, is the facility with which it can be repaired in case 
 of an accident. The bridge can be removed and the entire work 
 of re|)airing can be done in the laboratory, without the slightest 
 inconvenience to the i>atient. In the case of extensixc (hnnage 
 -to a fixed bridge, it is fre(|uently necessary to so cut and nnitilatc 
 it, in order to remove it from tlic niontli, as to nearly destroy it, 
 15 
 
226 REMOVABLE BRIDGE-WORK 
 
 necessitating, in many instances, practically the making of the 
 entire bridge over again. 
 
 This is especially true in a case where there are many abutments. 
 In making extensive restorations, where there are a large number 
 of anchorages, a fixed bridge should never be placed. It may 
 at any time happen, that in cementing a fixed bridge of this charac- 
 ter, from one cause or another, the cementing of one or more of 
 the abutments has been faulty, and before this is discovered, these 
 roots have been entirely destroyed through leakage and decay. 
 It would be impossible for this to happen in the case of removable 
 work, for should one of the abutment caps become loosened, it 
 will manifest itself at once by coming away with the bridge, in 
 which case it can easily be recemented, rendering the piece as firm 
 as ever. 
 
 Another very decided advantage in a removable piece is the 
 facility with which affected teeth adjacent to the bridge may be 
 treated. Every dentist has probably had the experience of under- 
 taking to place a gold filling in an approximal cavity in a tooth 
 adjoining a fixed bridge. 
 
 rf the bridge be removable, it can be taken from the mouth, 
 leaving ample room for any operation which may be necessary. 
 With the advent of cast gold inlays, these operations have been 
 much simplified. The insertion of such an inlay is not nearly so 
 difficult as was the putting in of a gold filling by the old method. 
 But the fact remains that we can much better place an inlay if, 
 by the removal of the bridge, we have ample room in which to work. 
 
 The value of removable bridge-work depends entirely upon 
 the attention given to the numerous details, and upon the accuracy 
 with which the work is done. The fittings must be as nearly perfect 
 as it is possible to make them, otherwise the work will not prove a 
 success. The training which one gets in doing this class of work, 
 tends not only to make him more proficient in bridge-work, but 
 more proficient in every branch of the profession, as the care and 
 skill required develops a delicacy of touch, and exactness in manipu- 
 lation to a far greater degree than does the ordinary routine of the 
 dental work-room. 
 
 ATTACHMENTS TOR REMOVABLE BRIDGE-WORK. 
 
 Retaining and Supporting Abutments. — There are two classes of 
 abutments in both fixed and removable bridge-work, and these 
 
RETAINING ABUTMENTS 227 
 
 are known respectively as retaining abutments, and supporting 
 abutments. 
 
 By a retaining abutment is meant an abutment which not only 
 gives support to the bridge, but also retains it in its proper position 
 in the mouth, as in the case of a Richmond crown, shell crown, 
 telescope crown and others of a similar character. 
 
 A supporting abutment is one which gives support to the bridge, 
 but has nothing to do with its retention. An example of an abut- 
 ment of this kind would be where a spur is resting in a gold filling 
 or in an inlay in an adjoining tooth, and serving simply to prevent 
 anv lateral movement and to resist the force of occlusion. 
 
 RETAINING ABUTMENTS. 
 
 There are many different styles of attachments for removable 
 work, and the writer will describe those which he has found 
 most useful, and which have the most variable application. In 
 discussing these different attachments, we will first consider those 
 which are most frequently indicated in the posterior part of the 
 mouth for the molars and at times for the bicuspids. The first of 
 these is the telescope crown. 
 
 The telescope crowns should not be confounded with the shell 
 crowns, which are simply, as the name indicates, shell caps fitted 
 to the stumps. The telescope crown is really a crown in which 
 one part telescopes the other with the ease and accuracy of the 
 slides of a telescope. 
 
 Telescope Crown. — This crown is especially adapted to the 
 molars, and where great strengtii is required, or where the gold 
 can be hidden, as far forward as the second bicusj)id, and at times 
 even the first, but should never be carried beyond the first bicuspid, 
 and rarely to that tooth. The telescopes may be used where there 
 are two retaining abutments, providing the telesco])e can be matle 
 of sufficient length to give a permanent and firm grij). 
 
 Alloys Suitable for Making Telescope Crowns.- The alloy suitable for 
 a telescope (Touii iiiiist possess great tensile streiigtii and rigidity, 
 and also a certain amount of elasticity. I'he 22 carat gold alloyed 
 with silver, which is most connnonly sold at the dental de])ots, is 
 altogether unsuitable for this work, the silver alloy rendering it 
 .soft, with the result that if this were used, the strain which is 
 necessarily brought to bear on the bridge will cause the gold to 
 
228 REMOVABLE BRIDGE-WORK 
 
 stretch and so render the crown worthless within a comparatively 
 short time. 
 
 The best results have been secured by using a copper alloy, and 
 the writer has found the American coin gold, 21.6 carats fine, to 
 be the most suitable for this purpose. It is tough, strong and rigid, 
 and experience shows that it will wear better than any other high 
 carat alloy.^ 
 
 It is not necessary, and perhaps not always desirable, that the 
 abutments for a removable bridge should be exactly parallel, but 
 they must be very nearly so. The pericemental membrane acting 
 as a cushion, permits of a slight natural spring to the teeth which 
 can be taken advantage of to help hold the bridge firmly in position. 
 If the natural inclination of the teeth is such that they diverge 
 slightly, they can be trimmed and the bands so fitted to them that 
 the bridge can be made to accommodate this inclination. The result 
 will be that as the bridge is placed in position, the teeth are drawn 
 together very slightly and then spread apart and resume their 
 normal position as the bridge is forced home. If the teeth converge, 
 when the bridge is put in position, they are forced apart very 
 slightly, resuming their normal position when the bridge is in place. 
 
 This movement of the teeth, of course, must be very slight, for 
 should it be very great, it would have a tendency to loosen the 
 teeth, but the slight natural spring will do no harm, and as before 
 stated, will help to hold the bridge more firmly in its place. 
 
 In a telescope crown which has been carefully and accurately 
 made, there will be practically no wear even after they have been 
 in use for years. The fluids of the mouth forming a coating which 
 protects the metal so that there is in reality no actual contact 
 between the outer and inner caps. On the other hand, if the fitting 
 has not been accurate, and there is the slightest play between the 
 outer and inner caps, there will be a very decided friction which 
 will, in a very short time, render the piece worthless. 
 
 The Technic of the Telescope Crown. — The trimming of a tooth 
 for a telescope crown is done in practically the same manner 
 as for an ordinary shell crown, being ground so that the stump is 
 tapering, and being slightly larger a little below the gum line, 
 the only difference being that the occlusal surface should be cut 
 
 ^ Within the past few years Mr. L. J. Weinstein, of New York, has been making 
 extensive experiments in dental alloys for this and other work, and has produced some 
 which gives excellent results. A chapter by him in another part of this work will 
 prove interesting and valuable reading, not only to the crown and bridge specialist, 
 but to the general practitioner as well. 
 
RETAINING ABUTMENTS 229 
 
 away a little more than for a shell crown, as there is a greater 
 thickness of metal at the occlusal end in a telescope crown than 
 in a shell crown. 
 
 The measurement of the stump is taken in the manner described 
 directly across. The band should be cut to this measurement, the 
 ends being nearly parallel, but not quite, flaring a little and being 
 slightly longer at the gingival edge (Fig. 374). The length from 
 
 Fig. 374 
 
 the occlusal to the gingival edge of the band should be such that 
 it will extend from well beneath the gum line to a little above the 
 occlusal end of the stump, or nearly in contact with the occluding 
 teeth. 
 
 The thickness of the gold of which the band is made should be 
 number 80 Brown & Sharpe gauge. One end is beveled to a knife 
 edge and the other overlapped and the two parts sweated together. 
 The band should then be shaped carefully to conform to the shape 
 of the stump and festooned accurately to follow the gum line, being 
 certain to have it nearly parallel with other abutments. In shaping 
 it to the stump, care should be used not to wrinkle the band, but to 
 keep it perfectly smooth. The gingival end should tlien be beveled 
 slightly from the outside, any feather edge which may have been 
 turned over by the scissors or the file being remo\ed, so that it 
 will pass freely under the gum without mutilating it or causing 
 the patient unnecessary pain. It should be remembered that the 
 occlusal end of the band should have exactly the same shape as 
 the gingival end, or in other words, the occlusal end of the band 
 should follow parallel with the gingival. 
 
 It is important that this be done accurately, for should the 
 occlusal end not have the same outline as the gingival end, if it be 
 pressed together too much mesialiy and distally, or buccally and 
 lingually, it will be conical from this direction (I<'ig. 875), but will 
 be forced out at the occlusal end at the other sides, giving it a 
 flaring top which would render it impossible to perfectly fit the 
 outer band fFig. 87()). 
 
230 REMOVABLE BRIDGE-WORK 
 
 The band is then placed on the stump, forcing the gingival 
 edge to nearly one-sixteenth of an inch below the gum line. An 
 
 Fig. 375 Fig. 376 
 
 impression is then taken and a model prepared in the manner which 
 has been already described. After the model has been separated 
 from the impression and neatly trimmed, the band may be removed 
 by grasping it with a pair of heated pliers. The model should 
 then be thoroughly dried, treated with several coats of thin sandarac 
 varnish and then again dried to harden it before proceeding with 
 the work. This being done, the band is replaced on the stump, 
 and enough of it cut from the occlusal end to allow for a thick 
 strong cusp. The extreme occlusal edge of the band is then 
 turned inward slightly all around (Fig. 377), care being taken to 
 keep the edge parallel with the gingival end of the band. 
 
 The object of turning the edge of the band in, is to give this 
 end of the cap a slightly rounded form in order to facilitate the 
 placing of the bridge over it in the mouth. If this were not done, 
 and the top of the cap was left with a sharp, square edge all 
 around, it can readily be seen by the illustration (Fig. 378), that if 
 
 Fig. .377 Fig. 378 . Fig. 379 
 
 the abutments were the least out of parallel, the edge of the outer 
 cap would catch on this square edge and render the insertion of the 
 bridge very difficult. If the top edge of the cap is rounded slightly, 
 the outer cap will slip over it from almost any position, and the 
 bridge can be dropped in place very easily. 
 
 The occlusal edges of the band having been turned in, this end is 
 filed perfectly flat and the floor of No. 28-gauge coin gold is flattened 
 in the swagging device and sweated to it in the same manner as 
 already described in the making of the cap for a Richmond crown 
 
RETAINING ABUTMENTS 
 
 231 
 
 (Fig. 379). The extending edges of the floor are then trimmed flush 
 with the band, and the sides of the cap are nicely smoothed with a 
 file or a fine disk and polished. The floor of the cap is not polished 
 at this time, the reason for which will be given later. 
 
 The inside of the cap is then given a very thin coating of wax. 
 After the wax is applied, all the excess that can be removed is 
 scraped away with the spatula. The cap is next grasped with pliers 
 and passed quickly through the Bunsen flame so as to distribute the 
 little remaining wax evenly, leaving only a very thin film. If 
 there is too thick a coating of wax on the inside of the cap, it can 
 easily be pulled away from the fusible metal stump, or it will be 
 found that when the outer band is driven over, the wax will be 
 squeezed out around the edges, allowing the inner band to buckle, 
 with the result that the work will have to be done over again 
 (Fig. 380). 
 
 Fig. 381 
 
 A tube of paper is then made, or a piece of rubber tubing may be 
 used, and the band pushed well down into it so that the gingival 
 edge is an inch or more below the upper end of the tube. The 
 paper tube should fit the caj) tightly, and is hehl in place with a 
 gum band or piece of wire (Fig. 3S1). The tube is now filled with 
 fusible metal which is allowed to cool thoroughly before renioving 
 the paper. Fig. 3X2 shows a ladle especially adajited for fusible 
 metal, when used in small (piaiitities. It has a long, narrow lip, 
 which allows of the riictal being poun-d iiit(» a very small open- 
 ing as the i>ai)cr tubes in which the caps are placed. The ladle 
 will also hold enough metal to p(;ur a large-si/ed die for a saddle. 
 
232 REMOVABLE BRIDGE-WORK 
 
 The metal used for this purpose should have a very low fusing 
 point. Melotte's metal, or any of the metals which require a 
 higher heat than the boiling point of water to melt, are not suitable 
 for this purpose. The metal which the writer has found most 
 
 Fig. 382 
 
 suitable for thus reinforcing the caps is made from the following 
 formula of Dr. CM. Richmond, which was published many years 
 ago in one of the dental journals. 
 
 Tin 20 parts. 
 
 Lead 19 " 
 
 Cadmium 13 " 
 
 Bismuth 48 " 
 
 100 " 
 
 They are not melted in the order of their fusibility, but in the 
 order in which they are given, as the metals combine better if 
 melted in this manner. A new crucible should be used for the pur- 
 pose, or one which has been used only for the making of the metal. 
 The tin is placed in the crucible and heated until it is entirely 
 melted and as soon as this has taken place, the lead is dropped in. 
 When this has also melted, the cadmium is added and when this 
 too has melted, the crucible should be taken from the fire, or the 
 fire should be turned out. The bismuth is then added in pieces 
 and stirred in with a pine stick until it is entirely melted. It must 
 not be forgotten to remove the crucible from the fire as soon as the 
 cadmium has disappeared. If this is not done before adding the 
 bismuth, the fusing point of the mass is lowered so rapidly that 
 the metal will burn and become worthless for the purpose for 
 which it is intended. 
 
 This metal fuses at about 160*^ F. It is quite hard and does not 
 shrink at all on cooling, and after using, it can readily be removed 
 from the gold cap by placing it in hot water. 
 
 The metal-filled cap having become quite, cold, the paper is 
 removed and a perfectly solid and rigid stump results, over which 
 it is possible to make a perfectly-fitting outer cap, and the surplus 
 
RETAINING ABUTMENTS 
 
 233 
 
 metal extending as it does over an inch or more beyond the cap, 
 makes a con^•enient handle bv which to hold it for further operations 
 (Fig._3S3). 
 
 It is well to emphasize the fact that the band should be thoroughly 
 polished before filling it with the fusible metal. Being reinforced, 
 and having the extending stump for a handle, it would be easier 
 to polish and finish it after it has been filled with the metal, but 
 there would be danger of future trouble should this be done. Should 
 the band be polished at this time, it would be impossible to prevent 
 the polishing wheels from coming in contact with the fusible metal. 
 The surface of the gold of the inner cap would thus become con- 
 taminated, so that in fitting the outer band it would in turn become 
 contaminated from the film of the base metal which has been 
 brushed over the inner cap, even th'ough it could not be seen, and 
 the band, at the first annealing, by alloying with the base metals 
 would become so brittle as to be absolutely worthless. 
 
 It cannot be too strongly impresse<:l upon the reader, the danger 
 of the precious metals becoming contaminated by contact with 
 base metals on the work bench. The greatest care should be used 
 to keep them from unnecessary contact. Even the slightest trace 
 of any of these base metals or alloys will, on the piece being heated, 
 as in annealing or in soldering, entirely destroy the working qualities 
 of the precious metals, so that they are good for nothing until 
 refined and remelted. All pieces swaged or fitted upon base metal 
 dies should be given a bath in nitric acid before 
 annealing or soldering. 
 
 The bench on which base metal has been used, 
 and the instruments which may have been used 
 around it, should be thoroughly cleansed before 
 again coming in contact with gold or platinum. 
 
 Making the Outer Cap. — The measurement of the 
 inner cap is taken just below the point where the 
 occlusal end has been rounded (Fig. 383, aa), and the 
 outer band cut from Xo. 30-gauge coin gold on an 
 angle of the same degree, or even slightly greater 
 than was the inner band (Fig. 374). This is then 
 beveled and sweated together in the same manner as 
 was the iimer band, and afterward the lapped joint 
 is hammered over the beck-horn of an anvil or 
 squeezed between the jaws of the stretching pliers until the seam on 
 the inner side is entirely obliterated. It is now annealed and given 
 
 Fio. ^83 
 
234 
 
 REMOVABLE BRIDGE-WORK 
 
 approximately the shape of the stump, and the inner cap is driven 
 into it by placing the occlusal end of the band on the anvil and 
 
 Fig. 384 
 
 Fig. 385 
 
 tapping the end of the fusible metal stump with a small hammer, 
 forcing it into the outer band which is thus stretched over it, as in 
 Fig. 384. 
 
RETAIN I Xa ABUTMENTS 
 
 231 
 
 It should not be allowed to come in contact with the fusible 
 metal except in such cases as will be described later. The band 
 will be foimd to fit the inner cap so tightly as to render it immovable. 
 This may be remedied by using a heavy steel burnisher (Fig. 385) 
 and burnishing the sides of the band as it fits over the inner cap. 
 This burnishing will stretch it very slightly, but sufficient to allow 
 of it being removed from the stump. It should not be burnished 
 so as to make it loose, but just enough to permit of it being forced 
 ofJ with an instrument. 
 
 The band is then marked and carefully trimmed to a line parallel 
 with the gingival edge of the inner band, and again driven on until 
 it comes to within a little less than one-sixteenth of an inch of the 
 gingival edge of the inner cap (Fig. 386). The occlusal end is trimmed 
 very nearly to the floor of the inner cap and then pressed in all 
 around over the rounded edge of the inner cap so that it fits at this 
 point closely (Fig. 386). This can be done with the face of a flat 
 
 Fig. .387 
 
 file by giving it a rolling motion, laying it flat on the side of the 
 band and rolling over the occlusal end. It should not be done by 
 burnishing as the burnishing would stretch the metal at this point 
 and make it impossible to obtain an accurate fit. 
 
 The occlusal end is then filed flush with the floor of the inner cap. 
 In doing this and in making it i)crfectl\' flat, it will be necessary to 
 Hie away some of the floor of the inner cajj and it was for this reason 
 that the floor was made of No. 28 gold (Fig. 387). We now have 
 an outer telescoping cap which fits the imier perfectly, atxl there 
 is no method which can be employed which will give so perfect a 
 
236 REMOVABLE BRIDGE-WORK 
 
 fit. The outer band is then removed and a floor of No. 30 coin 
 gold is sweated to it. Up to this point, no solder has been used, 
 so that in any subsequent soldering operations tJiere is no possi- 
 bility of any solder making its way to the inside of the cap through 
 the seams, and thus destroying the fit. 
 
 The edges of the floor are then trimmed flush on the buccal and 
 lingual sides of the cap, leaving it extend a little out from the cap 
 centrally on the mesial and distal sides, as in Fig. 388, to assist 
 in giving the cap a normal contour at these points. 
 
 Fig. 388 Fig. 389 
 
 It is essential that the contour of the cap or crown be restored 
 so that it will present a normal appearance. This is done by building 
 it out mesially and distally with coin gold. Pieces of No. 28 gauge 
 coin gold are used, being cut about one-half or three-quarters longer 
 than the buccal and lingual diameter of the cap and shaped approxi- 
 mately as in the drawing (Fig. 389), the gingival edge following the 
 festoon of the band and coming to within about one-thirty-second 
 of an inch of this edge and extending about one-thirty-second to 
 one-sixteenth of an inch above the occlusal end. 
 
 These pieces of gold are called the contour wings. One is placed 
 in position on the cap about one-thirty-second of an inch above the 
 gingival edge, the other side resting on the extended floor of the 
 
 Fig. 390 , Fig. 391 . 
 
 outer cap (Fig. 390). This allows only the lower edge to touch the 
 band and it prevents the solder from flowing farther up on the cap 
 than intended. If the floor has been trimmed close to the band 
 all around, the same result can be obtained by giving the wing a 
 short bend close to the gingival edge as in Fig. 391. It is held 
 in position with a pair of pliers and fluxed with liquid-flux^ between 
 
 1 A solution of borax and boracic acid. 
 
RETAINING ABUTMENTS 
 
 237 
 
 the wing and the cap. It is then held over the flame of a Bunsen 
 burner, drying the flux and thus holding the wing temporarily in 
 position. 
 
 The cap is then placed on a charcoal block, the side on which the 
 wing is tacked being uppermost, and it should so rest that the wing 
 is nearly level. A very minute piece of 21-carat solder, no larger 
 than a quarter of the size of a pin head is placed on the lower edge 
 of the cap in contact with the wing, as in Fig. 392. The whole is now 
 thoroughI>- heated up until the solder melts and the wing is tacked 
 to the band with this small piece of solder. The cap is then cleansed 
 in acid and the wing on the opposite side is attached in the same 
 
 Fig. 3!>2 
 
 Fig. :im 
 
 Fig. ;i!)4 
 
 Fig. 8<»5 
 
 manner. The cap is next placed on the stump and the wings are 
 brought into shape with the pliers so as to give a contour to the 
 crown, the ends being trimmed as may be necessarv to give this 
 result (Fig. 393). The fact of their being only just lightly tacked at 
 the gingival edge permits them to be adjusted outward or inward 
 or in any way desired to give the required contour. Fig. 394 
 represents an upper molar with the wings brought in proper posi- 
 tion and Fig. 395, a lower molar. 
 
 When the wings have been brought into shape, the spring of the 
 metal will be such as to keep the edges from actual contact with the 
 band. To overcome this, it is necessary to amieal them while held 
 in close contact, as follows: The edge of the contour wing is grasped 
 with a pair of pliers, one beak being inside of the band, and the 
 other resting on the edge of the contour wing, holding it in place. 
 The flame of the blow-pipe is then thrown onto the wing, bringing 
 
238 REMOVABLE BRIDGE-WORK 
 
 it to a red heat, holding it in the pliers, as in Fig. 396, until it is 
 cool. This will bring it in contact with the band, and overcome 
 the spring of the metal. This is repeated at different places until 
 all points of the wings are in contact with the band. 
 
 The cap is thoroughly cleansed in acid and after it is rinsed and 
 dried, it is well fluxed between the wings and cap and also around 
 the edges and buccally and lingually between the two wings. It is 
 now placed on a charcoal block with either the buccal or lingual 
 sides uppermost and a large piece of 21 -carat solder placed between 
 the ends of the wings, as in Fig. 397. 
 
 The whole cap is then thoroughly heated up with the blow-pipe 
 and the solder drawn in between the wings and the cap and along 
 the edges, using sufficient solder to flush it well between the edges 
 of the wings and cap, but not enough to more than partly fill in 
 between the contour and the band, as in Fig. 398. 
 
 Fig. 396 Fig. 397 Fig. 398 
 
 The cap is then cleansed again and soldered on the opposite side 
 in the same manner, bringing the solder flush between the ends of the 
 wings, also along the lower edge between the wings and the band. 
 It is then cleansed in acid and the extending wings cut and filed 
 flush with the floor of the cap (Fig. 398). A suitable cusp button 
 is selected, a pure gold matrix made, filled flush with coin gold and 
 the under surface filed perfectly flat. This cusp may be selected 
 after the band has been contoured, or it may be selected before and 
 the contour brought out to correspond with the cusp. 
 
 The edges of the cusp should extend slightly beyond the contour. 
 After it has been filed perfectly flat, the under surface is fluxed 
 as well as the floor of the cap at the point of contact and held in the 
 flame of the Bunsen with a pair of pliers, until the flux has dried, 
 thus tacking the cap and cusp together. The cusp and cap are then 
 wired tightly and placed on the charcoal block, as in Fig. 399. 
 
 A large piece of 20-carat solder is placed on the buccal or lingual 
 
RETAINING ABUTMENTS 
 
 239 
 
 side of the cap, resting on the extending edges of the cusp. The 
 flame of the blow-pipe is directed on the cusp which should extend 
 a little over a depression in the block so as to allow the cusp, which 
 
 Fig. .399 
 
 is \'ery thick and heavy, to be thoroughly heated up first, and the 
 solder melted (Fig. 399), flowing it in between the floor of the cap 
 and cusp. The cap can then be placed on its side, as in Fig. 400. 
 and the c-usp first heated thoroughly and the flame then passed over 
 
 Vui. 400 
 
 the u|jpcr and lower edge. Frcsii solder is added and as it melts, 
 it can be drawn through from one side to the other, uniting the 
 cusp and the caj) firmly. 
 
240 REMOVABLE BRIDGE-WORK 
 
 The solder should always be drawn from one point and enough 
 of the solder should be used to be certain that it is drawn entirely 
 through and filled flush all around the edges of the contour, uniting 
 the cusp thoroughly at all points. If the operator were to start at 
 one point and unite it there and then turning the crown and uniting 
 it at different points all around on the outside, he might afterward 
 find that it was perfectly soldered on the outside, but the solder 
 had not drawn entirely through from one side to the other, and 
 that the entire floor of the cap was not united to the cusp. The 
 possible result would be that in future operations, when the piece 
 has been very highly heated, that the floor of the cap at the point 
 where it was not united with the cusp may have expanded and 
 bulged inward as in the illustration (Fig. 401), leaving 
 a large blister at this point. If this does happen, 
 the cap may be placed on a block and the bulged 
 floor driven back into place with a stick. This can be 
 Fig. 401 accomplished so that very little or no harm will result, 
 but the appearance of the cap on the inside is spoiled. 
 After the cusp has been soldered, the extending edges are ground 
 off flush with the contour and the whole crown is finished and 
 polished. The outward appearance of the crown is now the same 
 as an ordinary contoured shell crown, but at the same time, it 
 fits the inner cap perfectly. 
 
 After the telescope crown has been completed, the inner cap is 
 removed from the fusible metal stump by immersing it in boiling 
 water. The cap is grasped in a pair of pliers and as the metal 
 softens, the cap is lifted from the water and any metal remaining 
 in it is shaken out while it is still hot. 
 
 The cap is then thoroughly dried and placed in chloroform to 
 dissolve any wax which may remain on the inner surface of the crown 
 after which it is placed in nitric acid and left for a time, or else 
 boiled in the acid in a test tube, so as to remove any traces of the 
 fusible metal, as the slightest trace of this metal left in the cap 
 would, should it be reheated, render it brittle and worthless. 
 
 Casting Cusps and Contour. — It is well to say a word at this point 
 in regard to casting the cusp and contour on the telescope caps. 
 It has been advocated by some, that the outer cap be made in the 
 manner described, up to putting on of the contour, and the cusp 
 and contour be then molded in wax. This is then invested and 
 cast in the customary way. A telescope crown made in this manner 
 will not fit the inner cap. The contraction of the metal is such that 
 
TELESCOPE CRO]VX AM) TUBE AM) SPLIT PIX 241 
 
 the outer cap will become too small, and it will be necessary to 
 grind it on the inside in order to make it go over the inner cap, 
 thus destroying the fit, and defeating the object to be attanied, 
 an accurately fitting telescope crown, besifle making the crown 
 unnecessarily heavy. 
 
 The contours of the telescope crowns are always mesially and 
 distally, except where the teeth are in an abnormal position. A 
 molar or a bicuspid may be turned one-quarter around. Then the 
 contour would be placed buccally and lingually, as the tooth stands 
 in the arch, but at the same time it would really be on the mesial 
 and distal sides of the tooth, as in the illustration. Fig. 402 shows 
 a rotated molar and Fig. 403, a bicuspid. 
 
 Fig. 402 Fig. 403 
 
 As previously stated, the telescope crowns should be used in 
 the posterior part of the mouth only, and never, under any cir- 
 cumstances, anterior to the bicuspids. 
 
 THE TELESCOPE CROWN IN COMBINATION WITH THE 
 TUBE AND SPLIT PIN. 
 
 . This crown is indicated where there is but a single retaining 
 abutment for a bridge, or where there are two retaining abut- 
 ments, but the crowns are so very short that it will be impossible 
 to get sufficient hold witli a simple telescope crown. It is nearly 
 always indicated in the lower third molar, and very fre(iuently in 
 the second lower molar. 
 
 As is usually the case with the lower third molars, the crown is 
 very sliort, and at times (mi the distal side, it is necessary to cut the 
 stumj> nearly Hush witii the gum, or even beneatii it, in onk'r to 
 place a cusp thick enough to give strength and support to the body 
 of the briflge which is to Ik; coimected with it. 
 
 It is also fn-cpieiitly indicated in the uj)i)cr mohirs, and at times 
 ill the lower bicusj)ids, but very rarely for th<' uj)|)er bicuspids. 
 
 The Construction of the Telescope Crown with the Tube and Split 
 Pin. The iiiiKT baud is iiiadc and fitted to the stumjj in exactly 
 16 
 
242 REMOVABLE BRIDGE-WORK 
 
 the same manner as for the ordinary telescope crown. If the crown 
 of the tooth is of sufficient length so that the depth of the pulp 
 chamber, from the floor to thp occlusal end of the stump, is in the 
 neighborhood of three-sixteenths to one-quarter of an inch, it is not 
 necessary that the tube should go in deeper than to the pulp chamber 
 floor. If, however, the crown is very short, it may be necessary 
 to drop the tube for a little distance into one of the roots. In the 
 lower molar, it is generally advisable to utilize the mesial root for 
 this purpose, as the position of these teeth is frequently such, that 
 the mesial root stands at a better angle to receive the tube, as in 
 Fig. 404. It is only necessary to drop the tube for a very short 
 distance into this root, and as a general rule, owing to the lingual 
 inclination of the tooth, it would be placed toward the lingual side. 
 
 Fig. 404 Fig. 405 
 
 In the upper molars, the palatal root is the best, as it is of a 
 greater size than are the others. The band is placed in position 
 and a heavy wire, of a slightly greater diameter than the tube 
 which is to be used, should be placed in the pulp chamber or the 
 enlarged canal, resting on the bottom, and held lightly in position 
 with some soft wax and bent so as to clear the bite, as in Fig. 405. 
 
 The impression and articulation are then taken. When the 
 impression has been obtained, the pin and band will often come 
 away with the impression. Should they not do so, they can be 
 removed and replaced in the impression, after which they are 
 properly waxed in place and the sides of the pin lightly covered 
 with wax. The impression is then varnished and the model is 
 made and separated in the usual manner, the band and pin 
 removed and the model dried. 
 
 The edges of the occusal end of the band are turned in slightly, 
 the same as in the regular telescope, and a floor of No. 28-coin gold 
 is sweated to it, and the excess gold of the floor trimmed away. 
 By observing the hole in the stump, where the heavy wire has been 
 removed, it can be ascertained about where the hole should be 
 drilled in the floor of the cap for the reception of the tube. The 
 
TELESCOPE CROWN AND TUBE AND SPLIT PIN 243 
 
 hole in the floor should be made of a diameter about one-half greater 
 than the diameter of the tube which is to be used (Fig. 40(j). The 
 tube, with the mandrel inserted, is then placed through 
 the opening, in the floor of the cap while the cap is on 
 the model, the lower end resting on the floor of the 
 pulp chamber or on the bottom of the cavity made 
 to receive it, and adjusted so that it will be parallel 
 with the anterior abutment (Fig. 407). 
 
 The tube must also be adjusted so that the outer cap, when the 
 crown is finished, with the pin in position, will draw freely from 
 
 Fig. 406 
 
 
 Fig. 407 
 
 the inner cap. This should be tested carefully while the tube is 
 waxed in position, before investing and soldering. This may be 
 done by leaving the mandrel in the tube and testing it from all 
 sides with a flat instrument or a small straight edge ])laced against 
 the .sides of the band, as .shown in the illustration (Fig. 40,S). The 
 cap being slightly conical, it is not necessary that the tube be 
 l)erfectly parallel with the sides of the band at any point, but it 
 mu.st be in such a ])osition that it will draw freely. 
 
 By placing the edge of a flat file on the side of the l)an(l on a line 
 with the mandrel, if, as the mandrel and file leave the band, they 
 are i>arallel or converge toward the upper end from all sides, it will 
 be known that the outer cap will pass over freely after the pin 
 has been soldered to it (Fig. 40S). On the contrary, if, as the man- 
 drel and file leave the band, they dixcrge, as in the illustration, 
 it can readily be seen that it will be inipo.ssible to make an outer 
 band which will fit the irnier band aeenrately and have it draw with 
 the pin of the outer cap in place, as shown in Fig. 409. 
 
244 
 
 REMOVABLE BRIDGE-WORK 
 
 As stated above, the diameter of the hole in the floor of the cap 
 should be considerably larger than the outside diameter of the 
 tube to permit, when the tube is soldered in place, of countersinking 
 
 Fig. 408 
 
 Fig. 409 
 
 it well at the entrance, so that the pin may readily find the open- 
 ing. The tube should be in the center of the opening and the wax 
 flowed around it to a depth of about one-thirty-second to one- 
 sixteenth of an inch beneath the floor. 
 
 The wax is then chilled, the mandrel removed from the tube, 
 and the cap invested, care being taken to have the inside perfectly 
 filled with investment, and it is then ready for soldering (Fig. 
 410). 
 
 The invested piece is then warmed slightly and the wax removed, 
 after which it is thoroughly dried out and heated to redness and the 
 tube soldered in place with 20-carat solder. This is best done by 
 using the solder in a strip, having first fluxed the tube and edges 
 of the floor at the opening. 
 
 The solder is held as shown in the illustration, and as the flame 
 of the blow-pipe melts it, it is pushed through the opening around 
 
TELESCOPE CROWN AND TUBE AND SPLIT PIN 245 
 
 the tube to the under side of the floor, fillhig the space which has 
 been left by the melted wax (Fig. 41 1). After it has been soldered, 
 it is removed from the investment, cleansed in acid and dried. 
 
 Fig. 410 
 
 Fig. 411 
 
 The tube should be thoroughly dried out before cutting off the 
 excess, as should moisture be left in it; the filings, working into 
 the tube, will form a sort of paste which is difficult to remove, 
 while if it is perfectly dry, the filings can be readily shaken out, 
 with the saving of quite a little time. 
 
 The cap is then smoothed and polished, waxed lightly on the 
 inside and filled with fusible metal, the same as for the regular 
 telescope. 
 
 The measurement is taken and the outer band made. In a case 
 of this character, where the crown is very short, it will probably 
 be necessary to carry the oiiter band <h)wn over the fusible metal 
 stump, for the time being, in order to s'ecure a fit and a hold on the 
 inner cap sufficient to allow of the turning in and filing of the 
 occlusal end of the band to conform with the inner cap, as shown 
 in the illustration (Fig. 412). 
 
 'I'he edges having been turned in at the occlusal end to conform 
 to the rounih'd corners of tlie iruier cap, it is filed flush with the 
 floor of the irmer caj), enough of the floor being filed oil to make 
 it perfectly flat and smooth on the surface. The outer band is 
 now removed and cleansed in nitric acid. T^nless this be carefully 
 ol)servcd trouble- will surely foll(»w. The gingival i-nd is sliortencd 
 
246 
 
 REMOVABLE BRIDGE-WORK 
 
 and festooned to follow the edge of the inner cap, but from one- 
 thirty-second to one-sixteenth of an inch shorter (Fig. 413), and a 
 floor of No. 30 coin gold is sweated to it. 
 
 Fig. 412 
 
 Fig. 413 
 
 In the making of a telescope crown it should be remembered 
 that after the outer band has been filed flush with the floor of the 
 inner cap and removed, it should always be wiped 
 out thoroughly on the inside before sweating the 
 floor to it. If this precaution is omitted or if any of 
 the filings or dust should adhere to the inside of the 
 band, they will become sweated to the sides during the 
 process of uniting it to the floor. This would render 
 the inside of the band rough, and would result in the 
 scratching of the inner band when the outer cap is 
 being removed or replaced. 
 
 The floor of the cap is trimmed, as in the case 
 of the regular telescope crown, being made flush on 
 the buccal and lingual sides and extending slightly 
 beyond the band mesially and distally. The band 
 is then contoured with wings and solder in the 
 same manner as in the making of a regular telescope 
 crown. 
 
 The opening in which to place the split pin should 
 
 now be located. The floor of the inner cap having 
 
 been filed perfectly flat and smooth, the inner edges of 
 
 the tube are sharp and clear, like the edges of a steel 
 
 Fig. 414 die. The outer cap is placed over the inner cap, and 
 
TELESCOPE CROWN AND TUBE AND SPLIT PIN 247 
 
 the floor of the outer cap, at the point over the entrance to the tube, 
 is placed on the end of a soft pine stick and the fusilile metal stump 
 struck a sharp blow (Fig. 414), indenting the floor into the tube 
 and leaving on the inside a clear sharp outline of the opening 
 (Fig. 415). _ 
 
 The next operation is to countersink the tube and tit the pin to it. 
 The split pin should tit in the floor of the outer cap tightly, so that 
 no excess of solder can pass through to the inner side of the cap; 
 in this it is not like the tube in the inner cap which fits loosely. 
 
 
 Fig. 415 
 
 Fig. 416 
 
 Fig. 417 
 
 Fig. 418 
 
 RJ3 
 
 Fig. 419 
 
 It is advisable here to emphasize a most important point which 
 applies in all cases where tubes are used. It is well known that 
 a molten mass of metal contracts on cooling. Thus the placing 
 of a large amount of solder around the tube results in its contraction. 
 It is evident that if the pin were made to fit the tube, without first 
 enlarging it at the opening, it would touch only at the point where 
 it had been soldered, leaving the lower end free in the tube. 
 
 For the sake of illustration, these conditions have been somewhat 
 exaggerated in the enlarged drawing (Fig. 416). It will be observed 
 that the contraction of the metal around the tube has drawn it 
 in so as to give it a neck smaller than the body of the tube. It 
 will be noticed that the only point of contact of the pin with the 
 tube is at the neck (Fig. 417) so that the entrance must be enlarged 
 at the opening in each case sufficient to allow the mandrel over 
 which the tube has been made to enter freely. This is best done 
 with a flame-shaped finishing bur (Fig. 418). After the neck has 
 been enlarged, the entrance to the tube is countersunk and 
 smoothed in order that the pin may readily find the opening (Fig. 
 419). It should be remembered that this is not to be done until 
 after the location of the entrance to the tube has been marked 
 in the floor of the outer cap. The pin is then made to fit the tube 
 and it should fit easily, but not loosely, or in other words, it should 
 fit. \ pin which fits a tube loosely does not fit at ah. 
 
248 
 
 REMOVABLE BRIDGE-WORK 
 
 The hole in the floor of the outer cap should now be made, the 
 marking on the inside giving the position. It should be enlarged 
 with the outer cap in position on the inner cap, just enough to 
 allow the pin to pass through it and fit the hole in the floor of the 
 outer cap tightly. 
 
 The selected cusp having been filled and filed perfectly flat on 
 the under surface, is then placed in position on the outer cap, the 
 pin for the time being having been removed. The under surface of 
 the cusp is marked through the opening in the floor which was 
 made for the pin (Fig. 420). 
 
 FiCx. 420 
 
 Fig. 421 
 
 The cusp is then removed, the pin replaced in the tube through 
 the floor of the outer cap, with the split of the pin running buccally 
 and linguall3^ The pin is waxed firmly in position, chilled, and the 
 outer cap with the pin in place is removed from the inner cap and 
 invested (Fig. 421). The inside of the cap should be moistened 
 before filling with investment, so that the operator may be certain 
 that it is perfectly filled and that there are no air bubbles, or any 
 unfilled space around the pin on the inside of the cap, which would 
 allow any of the solder to pass beneath the floor. It should then 
 be heated-up and soldered with 21 -carat solder, a very small piece 
 being used for the purpose. The flame is first thrown on the split 
 pin, as it is much heavier than the floor of the cap, until it is well 
 heated. The flame is then lowered to the floor of the cap, drawing 
 the solder around the pin and uniting it perfectly (Fig. 421). 
 
 A hole should then be drilled through the cusp at the point 
 marked through the opening in the floor of the cap and enlarged 
 sufficiently to allow it to readily pass over the pin extending through 
 the floor, leaving space on all sides, as in Fig. 422. The pin should 
 be cut off close to the floor so that when the cusp is soldered to the 
 cap, the pin will be entirely covered with solder. The pin should 
 
TELESCOPE CROWX AND TUBE AXD SPUT PfX 
 
 240 
 
 not extend abo^•e the cusp so that it may be seen, as the color 
 of this metal being much hghter than the cusps, if it is not covered 
 with solder will show and sj)oil the appearance of the occlusal 
 surface of the crown. 
 
 Fig. 422 
 
 Fig. 42.3 
 
 Fig. 424 
 
 The cap is invested, care being taken to fill it perfectly on the 
 inside. The investment should extend about half way to the occlusal 
 surface on the outside. The investment is now thoroughly dried 
 and the floor of the cap and the under side of the cusp is well fluxed 
 and the cusp is placed in position. It is then thoroughly heated 
 and soldered with 21 -carat solder, the .solder being used in a strip, 
 the end of the strip being placed in the opening through the cusp 
 over the pin (Fig. 428). As the solder melts, the strip is pressed 
 into the oi)ening until it is drawn through from this point to all 
 sides of the crown, and also filling the opening and covering the 
 pin fFig. 424). This is also an excellent way of uniting the cusp 
 to the outer cap in an ordinary telescope crown, making a smaller 
 hole in the center of the cusp, then wiring it in place and investing 
 and drawing the solder to all parts through the hole in the center 
 of the cusp. Soldered in this way there is little likelihood of there 
 being any point between the floor and the cus]) which is not ])crfectly 
 united. 
 
 The crown is now removed from the investment, cleansed in acid 
 and finished in the .same maimer as the regular telescope crown. 
 If, on carving the cusps, it is found that the pin shows through the 
 solder, it can be ground away with a bur or small stone and then 
 covered again with a small amount of solder. 
 
 The imiercap is then removed from the fMsiblc nictnl stnuij) and 
 
250 REMOVABLE BRIDGE-WORK 
 
 thoroughly cleansed with chloroform and nitric acid. It must be 
 remembered that the cap must not be put in the flame or reheated 
 again, until it is certain that every trace of the fusible metal has 
 been removed. 
 
 THE KEY AND SHOE ATTACHMENT. 
 
 Another stvle of anchorage, especially adapted to bicuspids 
 and molars having long crowns, is the dovetailed key and shoe 
 attachment. 
 
 The key is made of iridio-platinum and filed smooth to form a 
 dovetail, as in Fig. 425, A and B. 
 
 
 
 Fig. 425 Fig. 426 Fig. 427 Fig. 428 
 
 A strip of the iridio-platinum. No. 32 gauge, is bent to fit the 
 sides of the key perfectly and filed off flush with the face or broad 
 side of the key, and a floor of the same metal fitted to it and 
 soldered with a little pure gold (Fig. 426, A and B). 
 
 In using this form of abutment, the side of the crown to which 
 the key is to be attached should be straight from the gum line to 
 the top of the cusp and should be reinforced with a piece of No. 
 28-gauge coin gold soldered across the whole face of the crown 
 with 21 carat solder and polished (Figs. 427 and 428). 
 
 The key is then put in place, a hole drilled through it and the 
 side of the band to which it is attached with a small platinum 
 rivet, such as a tooth pin (Fig. 429, A,B), the under surface of the 
 
 Fig. 429 Fig. 430 Fig. 431 
 
 key having first been covered with pure gold, as the union between 
 iridioplatinum and the solder is not strong. The key may then 
 be tuned a little to the right or left, revolving it on the rivet 
 (Fig. 430) to make it parallel with the other abutment. 
 
REMOVABLE ATTACHMENT FOR ANTERIOR TEETH 251 
 
 After it litis IxH'H iuljiisti'd, it is soIcUtccI to the Cii]), usiiiu' a small 
 amount 20 carat solder which is ))lacc<l on the lower end of the key 
 next to the band at point r, Fig. 429, .1, and from there drawn to 
 the upper end of the key, uniting it firmly to the face of the crown. 
 
 The female part of the attachment, or the shoe, is then slipped 
 over the key and a thin piece of platinum plate cut out to slip down 
 over it next to the crowai (Fig. 431), and this is burnished closely 
 to it. It is then waxed to the shoe, removed, invested, and covered 
 with pure or coin gold, uniting it to the shoe and filling the sides 
 flush, as in Fig. 432. After having been cleansed, it is trimmed 
 to its proper dimensions, and replaced on the crowai. The facings 
 are now ground in and the bridge constructed. The shoe being 
 soldered into the end of the body of the bridge as in Fig. 433. 
 
 /^^^^^ 
 
 Fig. 432 • 
 
 If a saddle is to be used, the plate facing the crown, with the 
 shoe attached, is carefully fitted to the saddle. The saddle is then 
 waxed firmly to it, imbedding a piece of inm or brass wire in the 
 wax along the shoe and saddle to stifl'en it and prevent distortion 
 while removing it from the key and crown, invested and soldered 
 with 21 -carat solder. 
 
 The necessary trimming and fitting is now done and it is replaced 
 on the model and the bridge constructed, as will \)v described in 
 Chapter on Saddle Bridges. 
 
 REMOVABLE ATTACHMENT FOR THE ANTERIOR TEETH. 
 
 These atttachments are designed for the teeth anterior to molars, 
 where it is undesirable that any gold should be seen. The cap is 
 made practically the same as for a Fvichmond crown, the stump being 
 left standing out of the gum until after the tooth has been trinuned 
 and the band fitted. 
 
 In fitting the band to the root, care should be taken to have it 
 nearly i)arallel with the long axis of the tooth, as in Fig. 434, and 
 any excessive incliiiation in aii,\- direction as in I''ig. h')') should be 
 avoided. 
 
252 REMOVABLE BRIDGE-WORK 
 
 After the band has been fitted, the stump is faced in the same 
 manner as for a Richmond crown, except that it should not be cut 
 quite as far under the gum labially, for the following reason. In 
 
 Fig. 434 Fig. 435 
 
 a Richmond crown, the band should be from one- thirty-second 
 to one-sixteenth of an inch beneath the gum on the labial side 
 (Fig. 436), so that the band will be entirely hidden for a number 
 of years. If the same procedure be followed with a removable 
 piece, the band being far beneath the gum line allows the gum to 
 crowd over the edge of the cap and onto the floor when the bridge 
 is removed, so that when the bridge is replaced, the gum would 
 be pinched between the outer and inner caps, and a constant 
 irritation of the tissues result. 
 
 Fig. 437 
 
 The tooth should be trimmed from one-sixty-fourth to one 
 thirty-second of an inch below the gum line on the labial side 
 and should stand about the same distance above the gum line on 
 the lingual side and the band trimmed flush with it. The placing 
 of the floor on this will raise it high enough so that there will be 
 little liability of the gum coming over the floor sufficiently to 
 allow of its being pinched between the outer and inner caps (Fig. 
 437). 
 
 The canal is enlarged with reamers, which are made for the 
 purpose, as far lingually as possible for the reception of the tube. 
 
 The band is then faced off and a floor of No. 28-gauge coin gold 
 sweated to it. The surplus metal is trimmed away and a hole made 
 through the floor to allow for the placing of the tube in position. 
 
REMOVABLK ATTACHMENT FOR ASTKRIOR TEETH 23:5 
 
 As in the case of the telescope crown with tube and split pin, 
 the hole in the floor of the cap should be considerably larger than 
 the outside diameter of the tube, so as to allow the solder to run 
 through and provide for countersinking (Fig. 438). The cap is 
 then placed on the stump, the tube placed in the root and held 
 in position while it is being thoroughly waxed (Fig. 439). 
 
 Fu;. 4:is Fit;- 439 
 
 After waxing, the cap is chilled with cold air or ice-water and 
 removed from the root with the tube in position. This should 
 be tlone by passing a hooked instrument under the gum and oyer 
 the edge of the band, working from different sides, and mo^•ing 
 it a little at a time, so as not to change the position of the tube in 
 the cap. It should be noted whether the wax has drawn through 
 to the under side of the floor of the cap on all sides and should there 
 be any point at which it has not done so, a little wax may be added 
 and the cap again tried on the stump. 
 
 The cap is then invested, care being taken to have the inside 
 of the cap well filled with the investment, and soldered with 20- 
 
 carat solder. 
 
 The same care should be exercised in placing the tube through 
 the cap, to get the sides of the tube and the sides of the cap parallel 
 or so that the outer cap will draw, as in the case of the telescope 
 crown with the tube. The correctness of the inclination of the 
 tube .should be ascertained by i)lacing a flat instrument on the 
 lingual side of the cap and also on the mesial and distal sides, 
 the mandrel being left in the tube while the test is being made. 
 The correct relation of the tube on the lingual and mesial and dis- 
 tal sides of the cap is shown in Figs. 440 and 441, an.l un<ler no 
 consideration should they be placed in the position indicated m 
 Figs. 442 and 443. 
 
 If after the tube has been waxed in position and it together 
 with the cap is removed fn.in the root, a condition similar to that 
 shown in Figs. \V1 and 113 is found, it should be n-plaeed on the 
 root to see if the relation of the tube and a cap have not been changed 
 
254 
 
 REMOVABLE BRIDGE-WORK 
 
 in remo\'ing it from the stump. If it is found that it lias not changed, 
 it may be necessary to make a new band throughout, tilting it 
 enough in one direction or another so that a correct relation of the 
 tube and cap can be obtained. No attention need be given to the 
 relation of the tube to the labial side of the cap, as the half-band 
 engages only the lingual half of the inner cap. 
 
 Fig. 440 
 
 Fig. 441 
 
 Fig. 442 
 
 Fig. 443 
 
 After soldering, the cap is removed from the investment, cleansed 
 in acid and finished. The cap and the inside of the tube should 
 be thoroughly dried out before doing any filing or grinding. The 
 excess metal of the tube is cut away, the floor filed perfectly flat 
 and the neck of the tube opened so that the mandrel over which 
 it has been made, will enter freely, after which it is countersunk, 
 leaving the edges of the opening perfectly smooth (Fig. 444). 
 
 Fitting the Pin in the Floor of the Outer Cap.— The pin is then 
 fitted to the tube. The floor of the outer cap should be made of 
 No. 28 gauge coin gold. A piece of the metal, a little larger than the 
 cap, is selected, and the hole drilled through it at an angle corre- 
 sponding to the angle of the floor of the inner cap with the tube. 
 The pin should fit tightly into this, passing through the floor to the 
 bottom of the tube, care being taken that the outer floor fits closely 
 down to the floor of the inner cap at all points. The pin is then 
 waxed to the floor (Figs. 445 and 446). 
 
REMOVABLE ATTACH MEXT FOR AXTERIOR TEETH 2o5 
 
 As the strain on any bridge is always buccally and lingually or 
 labially and lingually, and never mesially and distally. in placing 
 the pin in the cap, the split should always extend from the labial 
 to the lingual sides, as in Fig. 447. 
 
 t 
 
 Fig. 444 Fig. 445 Fig. 446 Fig. 447 Fig. 44S 
 
 Thus strength of the pin is far greater if placed with the split 
 labially and lingually, than it would be if it were placed mesially 
 and distally. This can readily be demonstrated with a strip of the 
 half round wiTe, of which the pins are made (Fig. 448). It will be 
 found that it can be bent very easily flatwise, but in trying to bend 
 it edgewise, it will be very stiff. If the pin were placed with this 
 split mesially and distally any lateral movement would have a 
 tendency to bend the pin much more easily, the two surfaces 
 sliding together, but by having the strain come edgewise on the 
 pieces, far more than double the strength will be obtained than if 
 it were placed reversely. 
 
 Investment should be made as in Fig. 449, making a small invest- 
 ment corresponding with the size of the piece to be soldered, care 
 being taken to get the investment thoroughly around the pin on 
 the under side of the floor where it passes through it. Very little 
 solder should be used to connect this, the solder being placed at the 
 mesial side of the pin in contact with the floor (Fig. 449, «) the pin 
 and opening in the floor having previously been fluxed. It is then 
 soldered with 21 -carat sfdder. In soldering, the investment should 
 be first thoroughly heated-up and after it has reached a red heat, a 
 small blue flame is thrown directly on to the i^in which is so much 
 thicker and heavier than the H(.(»r that it requires a greater length of 
 time in heating up. The flame is held «»ii the pin until the melting 
 point of the solder is nearly reachetl. It is then gradually lowere<l 
 to the point of junction of the floor and pin and held there until 
 the solder flows entirely around. The ca|) is then rem(»ve«l from the 
 investment, cleansed in acid and dried. 
 
25G 
 
 REM VABLE BRIDGE- WORK 
 
 The pin and floor are now placed in position over the inner cap 
 and the floor trimmed just flush, and paraUel with the sides of the 
 cap (Fig. 450). This should be done with a file or a wheel, and care 
 taken not to trim it to a bevel, as in Fig. 451, but to leave it flush, 
 as in Fig. 450, otherwise when the half-band is put in position it 
 could not be brought in contact with the floor of the outer cap. 
 
 Fig. 449 
 
 Fig. 450 
 
 Fig. 451 
 
 Making a HaK-band. — The half-band should be made of the same 
 material and gauge as the floor of the cap, No. 28. It should not 
 come farther labially than the labial side of the pin and should 
 extend a little above the floor of the outer cap and down nearly 
 to the lower edge of the inner cap (F'ig. 452). It should be bent 
 and fitted carefully so that it is in contact with the floor at all 
 points, and when waxed tightly to the floor of the cap, removed 
 for investment. The piece should first be moistened on the under 
 side so that the investment may fill it thoroughly, as it is neces- 
 sary that the corners should be well filled so as to prevent any 
 solder from flowing through at this point. 
 
 Fig. 452 
 
 Fig. 453 
 
 On the lingual and mesial and distal sides, the investment should 
 be only high enough to engage the lower edge of the half-band so 
 as to hold it in position, as in Fig. 453. It is desirable to have the 
 investment far enough below the floor of the cap so that it may be 
 thoroughly heated at the point of contact between the half-band 
 and the floor, thus allowing of its being more easily soldered. The 
 investment is then dried out and the piece fluxed preparatory to 
 soldering. 
 
REMOVABLE ATTACHMEXT FOR ANTERIOR TEETH 257 
 
 There is a correct way ami a wrong way to solder the half-band 
 to the floor of the cap. In the correct way, the solder should always 
 be placed at one point and drawn from there all around where 
 it is necessary to unite the parts (Fig. 454, a). If two pieces of solder 
 are placed at different points, as in Fig. 455, a a, trouble is almost 
 certain to result. The piece is heated-up and the flame flashed 
 on to it, melting the solder at these two points. When the piece is 
 heated, the gold will expand, and in the half-band, it being a long 
 and narrow strip of metal, the expansion will be greater than it 
 will be in the floor. The half-band, being united to the floor at 
 
 a 
 
 Fig. 454 Fig. 455 Fig. 456 Fig.' 457 
 
 these two points, as in the illustration (Fig. 456, a a), when the 
 flame is thrown on the lingual side, it will expand lingually and be 
 pushed away from the edge of the floor (Figs. 456 and 457), with 
 the result that the solder is drawn down through, as in P'ig. 458, 
 resulting in an ill-fitting band. 
 
 Fig. 458 Fig. 459 
 
 If the solder is placed at the lingual side as in Fig. 452, when the 
 piece is heated from that side, to the melting point of the solder, 
 the solder draws the half-band closely in contact with the floor. 
 The metal expands as in the other case, but here it is lield 
 tightly to the lingual side and the ends of the (•xi)aiiding half-band 
 are free to move buccally along the sides of the floor. By first 
 melting solder at |)oint a, Fig. 454, and then throwing the fiaine 
 around both sides, the solder is drawn to the sides of the hiili'-biiiid, 
 uniting it to the floor perfectly. It is then removed from the in- 
 vestment and cleansed and the lower edge of the half-band trinnned 
 so that it will come not (|iiitc in contract with the gum (JMg. 15!)). 
 The outer bands of crowns of this t\pc or of a telescope crown 
 should never pass beneath the ginn margin. 
 17 
 
258 REMOVABLE BRIDGE-WORK 
 
 PRECAUTIONARY MEASURES TO PREVENT BROKEN FACINGS. 
 
 The making of the outer cap for this form of attachment requires 
 the greatest care, as the shghtest deviation in technic may result 
 later in great annoyance to both the patient and dentist through 
 a series of mishaps in the way of broken facings. 
 
 In almost every case where a patient presents with one of these 
 facings in the anterior part of the mouth broken, if the bridge is 
 removed and examined, it will be found that the under side of the 
 floor of the outer cap shows a very small polished surface jUst 
 at the labial side, at point a in Fig. 460 and Fig. 461. This shows 
 
 Fig. 461 Fig. 462 Fig. 463 
 
 that it was bearing heavily at the place so marked and touching 
 nowhere else, thus bringing the entire strain of the force exerted 
 in mastication on the facing at this point, with the inevitable 
 result that the facing is broken, as there is no porcelain made which 
 will withstand such a strain (Fig. 462). 
 
 This result may have been brought about by a slight deviation 
 in the technic in any one of the several steps taken in the making 
 of the outer cap. The first may have been in the soldering of the 
 pin to the "floor. In soldering, it must be remembered that the 
 tendency of the molten solder is to flow into corners and angles, or 
 between different pieces of metal which may be nearly, or quite, 
 in contact with each other. In the drawings, which have been 
 purposely somewhat exaggerated for the sake of illustration, will 
 be found the explanation of the causfe of the larger part of the 
 trouble from broken facings in the anterior part of the mouth. 
 
 In Fig. 463 is shown the floor with the pin in position, invested 
 and ready for soldering. As already stated, the solder is placed 
 on the labial side of the pin and resting against the floor at point 
 a, Fig. 463. If a large amount of solder has been used at this 
 point, what is the result? The piece is highly heated, the solder 
 is melted and naturally seeks the smallest space in which to lodge. 
 It is thus drawn from the labial to the lingual side of the pin, 
 
MEASURES TO PREVENT BROKEN FACINGS 259 
 
 almost the entire bulk filling in the narrow angle between the 
 floor and the pin (Fig. 4(33). The result is that there being so 
 great a bulk, as the solder cools, it contracts quite a little, chang- 
 ing the normal plane of the floor {a a, Fig. 464), drawing it up on 
 the lingual and consequently- depressing it on the labial side (Fig. 
 4li4, h b), with the re::ult that the floor will touch the floor of the 
 inner cap at this point, the labial side, and at no other. 
 
 It can readily be seen what the result would be if it were allowed 
 to remain in this condition, and the facing attached. The trouble 
 would have been obviated in the first place if only just enough 
 solder had been used to attach the pin to the floor. 
 
 The second step, where the trouble may have occurred, is in the 
 soldering of the half-band to the floor. In this, as in the previous 
 case, onl.\- a minute portion of solder should be used, only sufficient 
 to attach the half-band to the floor. 
 
 The pin, having been left long on the top of the floor and sloping 
 well lingually, may come nearly or quite in contact with the upper 
 edge of the half-band. If a large amount of solder is used in 
 soldering this half-band, the solder will flow in between the pin 
 (Fig. 465, a), and the floor of the cap and in cooling, as in the 
 first step, contracts and changes the plane of the floor (Fig. 466). 
 
 Fig. 461 Vm. 405 
 
 If it is found that the labial side of the floor has been depressed, 
 it should again be placed on the inner cap and the floor raised 
 slightly, so as to be clear, Ix-fore proceeding with the next opera- 
 tion. 
 
 The same thing may happen in the final soldering if the pin has 
 been long, even if, in the previous operations, only a very small 
 amount of solder has been used. The facings having been backed 
 and the piece invested, the solder may bunch up and cool between 
 the pin and the floor and so produce exactly the same results as in 
 the previous cases. 
 
 The cafj being comi)leted, tlie pin should be cut off close to the 
 floor of the cap before grinding the facing (Fig. 467). If this is 
 
260 REMOVABLE BRIDGE-WORK 
 
 done there will be no risk of trouble happening in the jfinal soldering 
 of the piece. 
 
 It should be remembered that the whole trouble is brought about 
 through the contraction of the solder on cooling, and the effect 
 
 Fig. 467 Fig. 468 
 
 of this should be carefully studied, not only in this, but in other 
 operations, as it is something that will have to be contended with 
 in all of our prothetic operations. 
 
 It is better that the floor of the outer cap should slightly clear 
 the floor of the inner cap at the labial side, rather than to press 
 heavily on it, because if the floors are not in actual contact at 
 that point (Fig. 468), there will be little probability of the facing 
 being broken, but if it rests heavily there, and at no other place, 
 as in Fig. 462, one may count on the facings being broken about 
 as fast as they can be put on. 
 
 When an accident of this kind occurs, and the floor is found to 
 press heavily on the labial side, the bridge should be placed in the 
 mouth and the outer floor lifted slightly off from the inner cap, 
 so that it will clear it or touch it but very lightly, by passing a thin 
 instrument, like a knife blade, between the two floors and raising 
 the labial side of the outer one slightly. If this is done when 
 the new facing has been replaced, there is little liability of its being 
 fractured. 
 
 INLAY ABUTMENTS. 
 
 The inlay abutment is another form of anchorage which is useful 
 for small bridges. 
 
 These attachments are especially indicated in the anterior part 
 of the mouth where but a single tooth is to be replaced, such 
 as a missing lateral or central, or a lateral and central incisor, 
 both on the same side of the mouth and at times even where 
 the four incisors are missing. They may be used in the cuspids 
 and centrals. In the back of the mouth they are frequently indi- 
 cated where a single bicuspid or molar, or molar and bicuspid is 
 
INLAY ABUTMENTS 261 
 
 missing, or at times even the two bicuspids and molar. An inlay 
 attachment may be used in the second molar, and in the cuspid 
 where it is desired to preserve the crowns of these teeth for esthetic 
 reasons. Frequently, where a molar crown is perfectly sound, 
 but the tooth is perhaps somewhat ill-shaped, so that it would 
 be almost impossible to prepare it and fit a band properly, it is 
 better to use the inlay attachment. 
 
 An inlay abutment is composed of an inlay through which a 
 tube is passed into the pulp chamber or pulp canal. Afterward 
 a second inlay with a split pin attached is used as the bridge 
 attachment. 
 
 In using these anchorages, it is always necessary to devitalize 
 the teeth. 
 
 Inlays for Anterior Teeth. — In the making of these attachments, 
 those for the anterior part of the mouth, the upper centrals or 
 cuspids will first be considered, all of the low^r incisors being too 
 frail for such an anchorage. 
 
 The tooth having been devitalized, the upper third of the canal 
 is carefully filled and the lingual surface of the crown cut away 
 from the side to which the bridge is to be attached to about two- 
 thirds of the distance across the crown, and extending down to the 
 gingivae, or near enough to it so that there will be room to allow 
 of sufficient bulk to the inlay to give support to the bridge and 
 at the same time aft'ord a good occlusion (Fig. 4()9). 
 
 The cavity is shaped somewhat as shown in the illustrations (Figs. 
 469 and 470), being made non-retentive, and the enamel edges of the 
 
 Fig. 409 Fi«- 470 
 
 cavity should be beveled so as to give more perfect margins. The 
 canal' is then enlarged for the reception of the tube. It should 
 be noted that 4 larger tube can be used in an inlay abutment than 
 could be used where the tooth is cut })eneath the gum labially, 
 as when using a porcelain crown or porcelain facing. The reason 
 
262 REMOVABLE BRIDGE-WORK 
 
 for this is that in the case of an inlay abutment the tube, starting 
 as it does considerably above the gingival line, it is not necessary 
 that it should go to a greater depth than about one-third or one- 
 half the length of the root below the gingivae, so that it occupies 
 only the broadest and heaviest part of the root. . 
 
 In the central incisor, a No. 4 tube may be used and at times 
 even a No. 5. A No. 5 tube is generally indicated for the cuspids. 
 The canal is enlarged somewhat lingually so as to give the tube 
 a slope in that direction which will allow plenty of metal between 
 it and the labial side of the cavity and permit of this being cut 
 away for the reception of the second inlay. 
 
 The cavity is moistened and the tube with the mandrel in it is 
 placed in the root and pressed well lingually so that it clears the 
 incisal edge of the tooth by a good margin (Fig. 471)7 
 The cavity is then filled with wax, the wax being 
 flowed in hot so that it will pass around the tube and 
 become well attached to it. The cavity should be well 
 filled and the wax carved so as to reproduce the 
 natural contour of the lingual surface of the tooth. 
 
 It will be found on removing the inlay and replacing 
 
 it again in the cavity that the shrinkage of the wax 
 
 on cooling has opened the margins, especially at the 
 
 gingival end. The wax should be trimmed lightly so 
 
 as to enlarge this space a little and the inlay is then 
 
 replaced and fresh wax flowed in the crevice. 
 
 Fig. 471 The wax should then be smoothed flush with the 
 
 sides of the tooth and a little more wax flowed over 
 
 the margins so as to leave something of a feather edge, after which 
 
 it is again removed from the tooth and prepared for casting. 
 
 The mandrel is grasped in the pin-vise and some of the wax 
 carefully trimmed away from around the mouth of the tube 
 where the cavity will be made for the second inlay, as shown in 
 the illustration (Fig. 472), after which the mandrel is removed. 
 This should be done very carefully so as not to mar or distort 
 the inlay. The mandrel being held in the pin-vise, a sharp instru- 
 ment is placed against the end of the tube and it is in this manner 
 forced off from the mandrel. In removing it, it is well to hold it 
 over a napkin or some soft material, so that should it drop from 
 the mandrel there would be no danger of marring the edges. 
 
 The sprue wire is then attached to the lingual side at tbe point 
 shown in the illustration (Fig. 473). The lower end of the tube is 
 
IXLAY ABUTMENTS 2()3 
 
 held in the pin-vise and the tube carefully filled with asbestos paper 
 or material of a similar nature, so that in casting there will be no 
 
 Fig. 472 pi^;. 473 
 
 possibility of any of the metal forcing its way into the tube. The 
 inlay is then flashed and cast. For these inlays, the writer prefers 
 pure gold as with it, much more perfect margins can be secured 
 than is possible with any alloy. If they are carefully made, after 
 setting, the pure gold inlay can be burnished and finished so as to 
 entirely obliterate any line of cement. 
 
 The inlay having been cast, is removed from the investment and 
 carefully cleaned, hydrofluoric acid being used to remove any 
 traces of silica which may be clinging to its surface. 
 
 The asbestos paper is removed from the tube and the tube 
 carefully cleansed and dried. It is then ready to form the cavity 
 for the second inlay. 
 
 It should be placed in the mouth and articulated, enough of the 
 gold being cut away so as to clear the occlusion, after which it is 
 removed and the cavity is made for the second inlay. This is 
 done before taking the final impression and articulation, as by 
 making the cavity at this time it forms a seat which will be a 
 guide when replacing it in the plaster impression after it has been 
 removed from the mouth. 
 
 The cavity for the second inlay is shaped in the same manner 
 as that for the first inlay, allowing a sufficient margin of gold to 
 remain at all points to give the required strength to the 
 attachment (Fig. 474). The cavity is smoothed so that 
 there will be no sharp edges which will scrape the ])laster, 
 after whicli the inlay is replaced in the mouth, and the 
 impression and articulation taken. After the impression 
 has been removed from the mtnith, the inlay is carefully 
 replaced in it, and great care should be exercised to be i'"^- '^''4 
 certain that it goes exactly into its proper position. 
 
 It is then firmly fastened in i)lace at two or three points at the 
 margins with a little sticky wax, after which u thin film of j)arafl^n 
 and wax is plarcd arouiul tlic tnbc. The whole inlay is then given 
 
264 REMOVABLE BRIDGE-WORK 
 
 a coating of cocoa-butter and the impression having been varnished, 
 the model is made and articulated in the same manner as for an 
 ordinary bridge. 
 
 After the model has been separated from the impression, the 
 inlay is removed by heating it slightly and in this case it is better 
 that the model should be thoroughly dried, and hardened, at least 
 around the tooth which received the inlay. This can be done, 
 after drying, by soaking it with thin sandarac varnish. 
 
 The finishing touches are now given to the inlay, by replacing 
 it on the articulated model and grinding a little wherever neces- 
 sary. The cavity in the inlay can readily be changed to suit the 
 existing conditions. It should then be made perfectly smooth 
 and the constriction at the neck of the tube removed with a flame- 
 shaped bur, so that the mandrel over which the tube was made 
 will enter freely. The finishing bur. Fig. 418, is best suited for this 
 purpose. The entrance to the tube is rounded somewhat with the 
 same bur. 
 
 The cavity can be smoothed ready for the pumice by using very fine 
 carborundum stones, or dull finishing burs, those of the pear-shape, 
 or rose-bur, being indicated, and if they are used wet, they will finish 
 it much more smoothly than if they are dry. A sharp bur will 
 not finish the cavity nearly as well as will a dull one, and the writer 
 when in need of a bur for finishing purposes and having only new 
 ones at hand, make it a custom to smooth them a little by running 
 them over an Arkansas stone before using them on the inlay. 
 After having been made smooth with the burs and being made 
 perfectly symmetrical, the cavity is finished with pumice and 
 rouge. This can best be done by using a wooden point in an engine 
 port polisher and after roughening the point somewhat, wrapping 
 a little cotton around it so that it will carry the smoothing and 
 polishing powder. 
 
 The Fitting of the Split Pin.^ — The next step is to fit the split 
 pin. The pin is made in the manner which will be described later, 
 with the exception that it is made about twice the length of the 
 tube, and the point of contact is also long, as shown in the illustra- 
 tion (Fig. 475), so that the point of union where the pin has been 
 soldered will come, when it is finished, just below the floor of the 
 cavity. It is carefully fitted to the tube and should fit it just 
 about as easily as the pin should fit the tube for an anterior crown. 
 
 It is then annealed and placed in the tube and a mark made just 
 at the entrance from the floor line at point a, Fig. 476. It is now 
 
INLAY ABUTMENTS 265 
 
 removed and placed, the finished closed end first, in the pin-vise, 
 carrying it in about one-thirty-second of an inch farther than the 
 
 Fig. 475 Fig. 476 
 
 mark showing the floor line. The vise should be tightened firmly 
 and the pin bent over by pressing it against the edge of the bench, 
 or by catching the end in a pair of pliers. 
 
 After bending it part way, it is best to re-anneal it before the 
 bending is finished. The pin is then bent nearly at right angles 
 or even farther so that it will follow the general direction of the 
 cavity (Fig. 477). 
 
 The pin should be bent in the direction of the split, as if it is 
 bent across the split, should it be held in the pin-vise very close to 
 
 Fig. 477 
 
 the soldered point of union, there is a possibility of breaking this 
 union and one of the halves sliding upon the other and thus destroy- 
 ing the fit of the pin. 
 
 The pin, having been bent to its proper shape, is filed open at 
 the end, care being taken to file it in the direction of the split and 
 the end is nicely rounded. Every thing is now ready for the making 
 of the «ec-ond inlay. 
 
 The Second Inlay. — The second iiila\' siioiild be made of a liardcr 
 metal than the first, such as coin gold, or some alloy equally hard 
 and which fuses at al)out the same temperature as does the coin 
 gold. 
 
 The second inlay may be made by inserting the pin in the tube, 
 building it up with wax and casting, but this will not make as 
 perfect an inlay as can be made in the manner described below, 
 but it can be used if desircfl. 
 
266 REMOVABLE BRIDGE-WORK 
 
 The method which the writer prefers in making a second inlay 
 is to first burnish a pure gold matrix into the cavity and after- 
 ward fill the matrix with coin. The pure gold should be of about 
 No. 36 gauge, great care being used in the burnishing to have the 
 margins as nearly perfect as possible. It should be annealed very 
 frequently during the operations and worked in very slowly, as in a 
 cavity of this kind, if the metal becomes the least bit hard from 
 burnishing, it is easily cracked. 
 
 After the matrix has been burnished in, a hole is made over the 
 entrance to the tube, so that the pin will pass through the matrix 
 and enter the tube freely. This having been done and the pin and 
 matrix having been removed, the cavity and entrance to the tube 
 are given a light coating of cocoa-butter. The matrix is then 
 annealed and it and the pin placed in position, the edges of the 
 pure gold extending beyond the sides of the cavity, and the cavity 
 is filled with a hard, sticky wax. The wax should be run in hot so 
 that it will pass all around and under the pin, and after it has been 
 chilled it should be pressed tightly down around the pin and over 
 the margins, forcing the pure gold matrix in close contact with 
 the edges of the cavity. It is then removed and is ready for 
 investment. 
 
 It is invested as shown in Fig. 478, and only a sufficient amount 
 of the investment used to hold the parts in position. The over- 
 
 %;A 
 
 
 Fig. 478 
 
 lapping edges of the matrix should be covered, but the investment 
 should not be carried over the cavity margins. It is then heated-up 
 to a red heat. 
 
 A button of coin gold of sufficient size to fill the matrix should 
 then be made and laid over the pin, the whole heated up well and 
 the button melted into the matrix so that it will fill it a little more 
 than flush, the same as in filling a cusp, after which the inlay is 
 removed from the investment and well cleansed in acid. 
 
 It is then dried, replaced in the inner inlay and finished. It should 
 be ground perfectly flush with the margins and from the second 
 
INLAY ABUTMENTS 
 
 26: 
 
 Fig. 479 
 
 inlay to the outer edges until it is finished and properly contoured. 
 It should be remembered that the cutting should be from the 
 center outward (Fig. 479), as if it were ground in the opposite 
 direction, the gold in the outer inlay would be burnished 
 over the second inla>' so that it would be impossible to 
 separate them. It is now ready for attachment to the 
 bridge. 
 
 This work is done on the model and after all of the 
 parts of the bridge are assembled they are waxed to- 
 gether, care being taken to wax it thoroughly to the 
 extending pin of the inlay. The piece is chilled and the 
 inner inlay removed from the otiter by grasping the tube and 
 pressing against the pin with a fine-pointed instrument or the edge 
 of a knife blade exercising great care not to use force at any other 
 point, otherwise the relation of the bridge and inlay might be 
 disturbed. 
 
 Before investing it for the final soldering, the inlay should be 
 coated well with antiflux (common whiting will answer for this 
 purpose), which will prevent the solder from flowing over the 
 margins and destroying the fit of the inlay. In finishing the piece, 
 great care should be exercised not to polish the pin or the inside 
 of the inlay. An old tube placed over the pin during the finishing 
 of the bridge will prevent any injury to it. 
 
 Inlays for Molars. — The cavities for the inlays for molars should 
 be large and take in a good part of the occlusal surface (Fig. 480) 
 extending on the side to which the bridge is to be attached down 
 to near the gingivae, as shown in the illustration (Figs. 481 and 
 482). 
 
 Fio. 480 
 
 Fio. 481 
 
 Fig. 482 
 
 ''i'he cavity is made non-retentive, and if there should be any 
 undercuts, they may be fill(>d in temporarily with gutta-percha 
 or cement. 
 
 The tubes for the molars should extend to the floor of the pulp 
 chanibcr and occasionally it may be necessary to deepen it on the 
 
268 REMOVABLE BRIDGE-WORK 
 
 mesial side, letting it drop into the root a short distance, as in the 
 case of a telescope crown with a tube and split pin. 
 
 It is desirable in these cases that pure gold should be used next 
 to the tooth structure so that a more perfect margin may be 
 obtained. As a general rule the pure gold should be about one- 
 thirty-second of an inch in thickness, and this will serve as a matrix 
 for the making of the main body of the inlay. A very thin piece 
 of wax, the pink paraffin and wax will answer nicely, and can be 
 readily worked into the cavity, covering the margins perfectly. 
 The sprue wire is attached to the distal end of the wax matrix 
 (Fig. 482), which is then removed (Fig. 483), flasked and cast in 
 pure gold in the same manner as an ordinary inlay. It has been 
 the general custom of the writer, however, to do this by the indirect 
 method, obtaining an impression of the cavity and then making 
 an amalgam die over which to make the inlay. 
 
 The die having been prepared, the wax matrix is made of the 
 desired thickness and fitted in the tooth before casting, being pressed 
 
 Fig. 483 Fig. 484 Fig. 485 
 
 firmly against the margins. The matrix need not extend entirely 
 to the bottom of the cavity as it is only necessary that perfect 
 margins be obtained, and that it be of sufficient depth to give body 
 to the inlay, as in Fig. 484. 
 
 The matrix having been cast in pure gold, it is fitted in the tooth 
 and the edges tapped in place with a stick of cottonwood so as to 
 make sure that the edges are in perfect contact with the margins 
 of the cavity. A hole is then made through the floor of the matrix 
 over the point at which the tube will rest (Fig. 485). This hole 
 should be considerably larger than the diameter of the tube, which 
 is to be used. Pink paraffin and wax is then pressed through the 
 opening to the bottom of the cavity in the tooth and pressed in 
 over the floor of the matrix so that it will be firmly attached (Fig. 
 486). The impression and articulation is then taken. 
 
 The impression having been removed from the mouth, the gold 
 matrix is removed from the tooth, great care being taken not to 
 disturb the wax. This is replaced in the impression and caught at 
 
I XL A Y AB U TMENTS 
 
 269 
 
 Fig. 486 
 
 two or three points with sticky wax so that it cannot shift its posi- 
 tion. The impression is then varnished and the underside of the 
 inlay given a Hght coating of cocoa-butter and the 
 model is prepared. After it has been separated, the 
 inlay and wax are removed and the model dried and 
 hardened. The inlay is replaced on the model, the 
 wax which was beneath it ha\ing gWen a perfect re- 
 production of the shape of the cavity. 
 
 The inside of the matrix should now be coated very 
 lightly with cocoa-butter so that the wax will draw 
 easily. The tube, with the mandrel inserted, is then 
 placed in the cavity extending through the opening in the matrix 
 to the floor of the pulp chamber or the bottom of the cavity which 
 has been made to receive it, and the inside of the matrix filled 
 with inlay wax, running it in hot so that it will attach itself to the 
 tube (Fig. 487). 
 
 The tube resting on the floor of the pulp chamber can be made 
 parallel with the anterior abutment hx leaving the mandrel in 
 any direction desired, the bottom of the tube remaining immovable 
 at the bottom of the pulp chamber or cavity (Fig. 487). 
 
 Fic. 4S7 
 
 Fig. 488 
 
 The wax should then be cut a\va>' from around the top of the 
 tube, roughl.\' shaping the caxity for the final inlay and the sprue 
 wire attached on tlic mesial side, as in Fig. 488. 
 
 It is tfieii reinoNcd from the pure gold matrix and the mandrel 
 remo\fd from the tube which is packed with asbestos \ni])vT in the 
 
270 REMOVABLE BRIDGE-WORK 
 
 manner previously described. It is next flasked and cast with coin 
 gold, after which it is well cleansed in hydrofluoric acid. After 
 cleaning and drying, it is placed in the pure gold matrix in order to 
 ascertain that it fits perfectly. The underside of the matrix is 
 covered with whiting so that no solder will flow over and destroy 
 the fit in the tooth and the two are united with 21 -carat solder, 
 the solder being placed at some point between the pure gold matrix 
 and the coin, as at point a in Fig. 489, and drawn through entirely 
 from that point until the pure gold and coin are perfectly united. 
 The cavity is now ready to be prepared for the final inlay. 
 
 Fig. 489 Fig. 490 
 
 The tube is cut off to the floor of the cavity and the coin gold 
 cut away, making the cavity a little larger around the tube, giving 
 it something the shape of a key-hole, looking from the occlusal 
 surface, so that it will not be necessary to depend entirely upon the 
 split pin for retention (Fig. 490). 
 
 The cavity is finished so that it is perfectly symmetrical in shape 
 and then polished, the entrance to the tube having been opened 
 so that the mandrel over which it was made will enter freely. 
 The pure gold matrix is burnished in place, the pin fitted to it and 
 the inlay completed in the manner already described in the making 
 of the anterior abutments. 
 
 Before cementing the inlay in place, any gutta-percha or cement 
 which has been placed in the tooth to obliterate undercuts, should 
 be removed in order that the inlay may become firmly attached 
 with cement. 
 
 It is an advantage to have the bridge worn for from twenty-four 
 to forty-eight hours without cementing in order to allow for the 
 settling of the piece, and for the abutments to accommodate them- 
 selves to it. Where there is an inlay abutment such as the one 
 just described, the inlay is always set separately, as there is only 
 one way in which an inlay can go into place and it must go to its 
 proper place or it will stand away from the margins of the cavity 
 at one point or another with the result that the cement will wash 
 out and decay take place. 
 
INLAY ABUTMENTS 271 
 
 After it lias been carefully articulated, finished and cemented, 
 the edges of the pure gold matrix are burnished over the edges 
 of the cavity and it is polished finally. In this way more perfect 
 margins ma,\- be secured. 
 
 Inlays by the Matrix Method. — In the absence of casting machines, 
 inlays may be made by the matrix method so that they will be 
 as perfect as those made by casting. The cavities are prepared 
 in the manner already described. A matrix of pure gold, as heavy 
 as can be worked into the cavity, is then burnished into place, 
 or a very thin platinum matrix may be used, burnishing it in the 
 same manner as for a porcelain inlay. The matrix must be carried 
 over the cavity margins and made as perfect as possible (Fig. 491). 
 
 The matrix is then annealed and put back in the tooth, the 
 tube placed in position (Fig. 491) and waxed well with hard sticky 
 wax, filling the matrix to the cavity margins. When the wax has 
 cooled, it is packed tightly in place around the margins of the 
 cavity so as to press the matrix in perfect contact. The matrix 
 is then removed and the tube filled with asbestos paper or fiber, 
 and the whole invested (Fig 492). 
 
 Fig. 491 Fig. 492 
 
 If a pure gold matrix has been used, the matrix should be filled 
 with coin gold, but if the matrix has been of platinum, then it can 
 be filled with pure gold. After cleansing it is dried out and the 
 cavity prepared for the second inlay, the technic in this case being 
 exactly the same as for the cast inlays, which has already been 
 described. 
 
 In very small pieces, or in the anterior part of the mouth, where 
 the teeth are small, the second inlay may be done away with by 
 fitting and bending the pin so that it will rest in the bottom of a 
 groove which has been made to receive it (Fig. 493). The groove 
 should be made the size of the split pin which is to be used and 
 after it is completed, the extending end of the pin should be sol- 
 dered into the bridge. This will answer the i)urposc aiifl do as well 
 
272 REMOVABLE BRIDGE-WORK 
 
 in carrying a small bridge as if there were a second inlay, but it 
 does not make quite as clean a piece, as there will be a groove on 
 
 Fig. 493 Fig. 494 
 
 either side of the pin as it rests in the inlay. Neither is it quite as 
 strong, and where strength and rigidity are desired the double inlay 
 should be used. 
 
 Inlay abutments may sometimes be used in the lower bicuspids, 
 especially if they are made so as to restore a part or the whole of 
 the occlusal surface of the tooth, in which case the tooth is beveled 
 from the inside outward and downward toward the gum, as is 
 Fig. 494, and, as will be seen, there is practically no possibility of 
 the tooth being fractured by the pressure. In the upper bicuspids, 
 however, the inlay is very rarely indicated, as the crowns of these 
 teeth are never very strong and very little force would be required 
 to bring about their fracture. 
 
 SUPPORTING ABUTMENTS. 
 
 The anchorages so far described have been retaining abutments 
 and the supporting abutments will now be considered. As pre- 
 viously stated, the supporting abutment gives support against 
 vertical and lateral stress and has nothing to do with the retention 
 of the bridge. 
 
 Supporting abutments may be in the form of gold fillings or 
 of inlays, the gold fillings being countersunk to receive the spur. 
 A hooked spur of platinized gold or iridio-platinum resting in a 
 countersunk gold filling or an' inlay forms an excellent support 
 for one end of a bridge. This is especially the case in the lower' 
 jaw, where it will safely support one end of a bridge consisting 
 of two or three or even more teeth and having but a single retain- 
 ing abutment. 
 
 In the upper jaw, with a crown carrying a single dummy, the 
 other end may be supported by a spur in countersunk filling or 
 an inlay. They are often useful, too-, in giving extra stability to 
 
SUPPORTING ABUTMENTS 273 
 
 a larger bridge which has two or more retaining abutments, but 
 which may require some additional support. 
 
 Gold Fillings. — Where a spur is to rest in a filUng in any of the 
 anterior teeth, either upper or lower, the ca\ity is made in the 
 palatal or lingual side of the tooth and also extending for a distance 
 over the side next to the bridge, as in Fig. 495. Where the bite 
 does not interfere, the cavity is made just at the basilar ridge 
 where the enamel is very thick, and should be of good size, 
 approximately about one-eighth of an inch in diameter. 
 
 The cavity should be started with a small carborundum wheel, 
 plenty of water being used to cut through the enamel and give the 
 general outline to it, before putting on the rubber dam. The 
 rubber dam having been adjusted, the cavity is deepened with 
 burs as much as possible without endangering the pulp. The 
 cavity is well undercut and a filling of hard gold, thoroughly con- 
 densed, is inserted. It is made large enough so that the contour 
 
 Fiu. 495 Fig. 4'JG Fig. 497 
 
 of the tooth is somewhat exaggerated, as in Fig. 4()(), but not 
 enough to interfere with the articulation. 
 
 The filling is then polished and a hole drilled in the center of 
 it on the palatal side to within a short distance of the bottom of the 
 cavity, the base of the hole being shaped with a bud-shai)ed bur 
 about the size of the No. 14 to IG gauge wire of which the spur will 
 l)e made. A groove of the same size is then cut from this ()])ening 
 to the distal side of the filling, care being taken to allow a strong 
 borjy of gold remain underneath and around it so as not to weaken 
 the filling (Fig. 497, a b). 
 
 IJefore taking the impression, a small amount of ])ink wax is 
 pointed and pressed into the bottom of the cavity and into the 
 groove, and the impression taken in plaster in the ordinary maimer. 
 When the impression is removed from the mouth, the pink wax 
 will come away with it, giving a perfect im[)ressi()n of the cavity 
 and groove in the filling. If the impnjssion is taken without the 
 
274 REMOVABLE BRIDGE-WORK 
 
 wax, the fine point of plaster extending to the bottom of the cavity 
 will be- broken away and will not give a perfect impression in the 
 model. The model is then made and after it has been trimmed and 
 hardened, the fitting of the spur and the balance of the work is 
 done on it. 
 
 The Inlay as a Support. — In using a gold inlay as a support for 
 the spur, the operation is simplified, and the spur can be made of 
 any shape desired with a certainty of its fitting the cavity properly, 
 A slight notch or groove is made in the tooth, before taking the 
 impression, where it is desired that the spur should rest, in order 
 that the position on the model which the spur is to occupy may be 
 located. The spur may be in the form of a hook, especially in the 
 anterior part of the mouth (Fig. 498), or in the form of a dovetail 
 
 Fig. 498 Fig. 499 
 
 (Fig. 499). The latter is especially applicable in the case of the 
 molars where greater strength is required. 
 
 The object in making the spur in the shape of a hook or dove- 
 tail rather than having it straight and flat, is that it may bind the 
 teeth together so that there is no possibility of their spreading, 
 which might happen should there be a smooth piece of wire resting 
 in a groove. 
 
 The plaster tooth is cut away sufficiently, at the point indicated 
 by the notch or groove, to allow for the resting of the spur, and the 
 bridge is constructed with the spur made so as to rest in the cavity. 
 When the bridge is completed, the natural tooth is cut away roughly, 
 where the spur is to rest, so as to allow the bridge to drop into 
 its proper position. It is well to allow the patient to wear the 
 bridge for a day or two before cementing. 
 
 When the bridge, if it be removable, has been cemented, and 
 the cement thoroughly hardened, it is removed from the mouth 
 and the making of the inlay undertaken. The cavity for the spur 
 is enlarged sufficiently to allow of a good bulk of gold on all sides, 
 extending well down on the approximal side of the tooth. On this 
 side the cavity can be made very shallow, as there is no strain 
 here and the gold over this surface is simply to protect the tooth 
 from decay, which is very necessary in the case of fixed bridges, 
 but not so important where the bridge is removable. 
 
SlirrORTING ABVTMKNTS 275 
 
 The sides of the cavitN- should he made as nearly parallel as 
 l)ossihle. hut it must he made non-retentive. The wax is then placed 
 in the cavity and the hridgc* slightly warmed and j)laced in position, 
 the spur pressing its way into the wax. The wax is then trinnned 
 to the margins of the cavity. The bridge is removed and rci)lace(l 
 several times in order to be positive that the spur has made a good 
 seat. 
 
 The s])rue wire is then fastened to the wax, which is remox'ed 
 from the tooth, invested and cast, either with pure gold or an 
 alloy. After it has been cast and cleansed, it is first tried in the 
 cavit\' and the bridge is adjusted to it. It is then removed, the 
 sides roughened, the cavity undercut slightly, and the inlay 
 cemented. After the cement has thoroughly set, the inlay is care- 
 fully polished and the bridge placed in the mouth. In the case of 
 a fixed bridge, the inlay is i)repared before the final cementing. 
 
 By making the inlay in the manner descri})ed, it is certain that 
 the spur is perfectly seated, which is not always the case where the 
 gold filling has been used as a rest. 
 
CHAPTER XIII. 
 TUBES AND SPLIT PINS. 
 
 Among the most important accessories in removable bridge-work 
 are the tubes and split pins. In order that they be effective, it is 
 necessary that they should be made with the greatest accuracy. 
 The tubes should be perfectly round and smooth on the inside and 
 the split pins, which are to be used in them, should be made so as 
 to fit perfectly, otherwise they will be of but little value. 
 
 The metal of which the tubes are made should be hard, 
 tough, rigid and non-oxidizable. The best alloy for the purpose 
 is iridio-platinum, the alloy containing approximately 10 per 
 cent, of iridium. If the dentist is specializing in bridge-work, 
 or is doing a large amount of it, it would perhaps be better and 
 cheaper to have the tubing made by a platinum manufacturer 
 who makes a specialty of work of this character. Should this 
 not be the case, the tubes may easily be made by the operator. 
 When the writer first began the making of removable bridge-work, 
 he made his tubes by drilling a solid iridium-platinum wire with a 
 twist drill of suitable size on a jewler's lathe. It developed, however, 
 that a drilled tube was not a good tube. It makes little difference 
 how sharp the drill may be, or how smoothly it cuts, the tube will 
 always be rough on the inside, the drill leaving a minute thread 
 which, no matter how fine it may be, will wear down quickly, and 
 entirely destroy the fit of the pin in the tube. Tubes may be made 
 with a draw plate, but a drawn tube is never perfectly straight, 
 and before using them, it is necessary to drive a mandrel through 
 in order to straighten them. 
 
 Making Tubes by the Mandrel Process. — A simple and easy method 
 of making a good tube and one which the writer has largely 
 employed for a number of years, consists of working them over 
 steel rods or mandrels made for the purpose and is as follows: 
 
 The Mandrels. — The set consists of six mandrels made from 
 regular sizes of Stubb's steel wire, which can be procured at dealers 
 in machinists' and jewelers' supplies. The gauge numbers run 
 from 48 to 53 inclusive, the sizes of the wire being, respectively, 
 .075, .072, .069, .066, .063 and .058 of an inch in diameter. 
 
THE MANDRELS 2/7 
 
 These rods are cut in lengths of about one and one-hah' inches, 
 and the ends carefully rounded. For convenience, they may be 
 numbered from one to six, by marking them with rings around one 
 end, according to the size of the mandrel, 
 beg'inning with the smallest, Nos. 1, 2, 3, 4, 
 etc. (Fig. 500). 
 
 In tempering the mandrels, they should be 
 heated to a cherry red (it is best to heat them 
 on a charcoal block), and then plunged in 
 water to harden them. In plunging them in 
 the water, they should be grasped with the 
 pliers by one end so that they will hang verti- 
 cally and enter the water in this position. If 
 they are plunged in sideways, so that one side 
 of the mandrel becomes chilled before the other, fig. oOO 
 
 they are more apt to be sprung or distorted. 
 
 They are then dried off and polished with cuttlefish or other 
 very fine grit paper. The heating and chilling having made them 
 extremely hard and brittle, it will be necessary to soften them 
 somewhat to prevent their breaking, which may be done preferably 
 by laying the mandrels on a piece of heated metal until they assume 
 a color indicating the desired temper, when they should be again 
 plunged into cold water endwise. The mandrels should be of a high 
 spring temper and should be drawn down until the color is between 
 a deep straw and a pigeon blue. This gives them the right degree 
 of hardness, after which they may again be polished, or they can 
 be used without polishing. 
 
 It is a good plan when the mandrels are first heated up, before 
 they become red, to plunge them into a cake of soap and then 
 proceed to heat them up to a cherry red. This will prevent oxidation 
 of the metal, and they will come out cleaner than they otherwise 
 would. 
 
 Another method of j^rocedure for the beginner, or for those not 
 familiar with tempering steel, and which will perhaps answer the 
 purpose for which the mandrels are intended, is to bring them to 
 a cherry-red heat and then plunge them into a heavy oil. They 
 are next held in the (fame of an alcohol lamp or a Buiisen l)uriier 
 until the oil is burned off, and then j>lunged into water. This 
 will soften the mandrels so that they will have a fair spring temper. 
 After the oil is burnt off, they should be carefully smootlied and 
 polished. 
 
278 
 
 TUBES AND SPLIT PINS 
 
 The Tubes. — The material of which the tube is to be made, 
 iridio-platinum plate, containing about from 7 per cent, to 10 per 
 cent, iridium and of No. 32 gauge or .008 of an inch in thickness. 
 If the plate is about seven-sixteenths of an inch wide, it will be 
 of sufficient width to give ample length for any tube that may 
 be required. The strip should be cut lengthwise with the grain 
 of the metal as it has passed through the rolling mill. 
 
 In making the tube, the plate is first annealed, the end squared, 
 and beveled with a fine file to a knife edge (Fig. 501). A hammer- 
 
 FiG. 501 
 
 headed hand-vise is necessary in making the tubes, as it is very 
 strong, and the jaws open and close on perfectly parallel lines 
 (Fig. 502). The serrations should be ground off so as to leave the 
 
 Fig. 502 
 
 jaws perfectly smooth on the inside, and the outer edge of one of 
 the jaws should be slightly rounded. The end of the iridio-plati- 
 
 FiG. 503 
 
 num plate is grasped in the jaws of the hand-vise and bent slightly 
 upward, the beveled edge being underneath (Fig. 503). 
 
THE TUBES 
 
 279 
 
 The mandrel is then hiid across the iridio-])hitinum plate, the 
 turned up edge of the plate ])reventing it from rolling off. It is now 
 grasped by the hammer headed hand-vise, one jaw engaging the 
 mandrel and the other the upturned edge of the plate (Fig. 504). 
 The plate is then bent around the mandrel, as shown in the illus- 
 
 FiG. 504 
 
 tration, until the beveled edge has passed the center of the mandrel, 
 so that it will not drop out if it is raised above the level of the 
 opposite end (Fig. 505). 
 
 Fig. 505 
 
 The plate, with the mandrel in position, is next laid on a flat 
 hard surface, such as the face of the anvil, or on a flat, smooth file. 
 The end of a flat course file, say a No. 2 cut, is held in such a i)osition 
 as to catch the beveled edge of the platinum. The other end of the 
 plate is held tightly with the fingers of the left hand and the file 
 pres.sed downward and backward against the iiiiindrel, as is shown 
 in Fig. 500, the plate being rolled around it until the beveled edge 
 is in contact with the lower si<le of the plate, as shown in the 
 illustration (Fig. 507j. It is very important that it should be 
 
280 
 
 TUBES AND SPLIT PINS 
 
 rolled only until the beveled edge is exactly in contact with the 
 plate, for the following reasons: It is desirable to use as large 
 a tube or pin in a tooth as the root will permit, the difference in 
 
 Fig. 506 
 
 the size of the mandrels is .003 of an inch, with the exception of 
 that between the first and second, in which the difference is 
 .005 of an inch. The plate used for making the tubes is of No. 32 
 gauge, or .008 of an inch in thickness. If in rolling the tubes, the 
 lap is carried beyond the point of contact, as shown in Fig. 508, 
 
 Fig. 507 
 
 Fig. 508 
 
 Fig. 509 
 
 there will be an extra thickness of metal on that side. It can readily 
 be seen that this extra thickness of metal will give an outside 
 diameter of the tube that will be .008 of an inch greater than it 
 would were it brought exactly in contact with the beveled edge 
 (Fig. 509). The result would be that the hole in the root would 
 have to be made as large to accommodate a tube so made as though 
 it were intended to use a much larger tube, being 0.008 of an inch 
 larger or nearly the difference in size between three mandrels. In 
 other words, if this extra lap is made it would be necessary to 
 have an opening in the root for a tube made over a No. 2 mandrel, 
 
THE TUBES 
 
 281 
 
 as large as would be required for one which had been properly 
 made and finished over a Xo. 5 mandrel. 
 
 The tube having been rolled in the proper manner, the mandrel 
 is removed and the seam soldered with pure gold, no flux being 
 used. A small piece of pure gold is laid on the plate, being in contact 
 with the plate and lower side of the tube (Fig. 510). It is then 
 
 Fig .510 
 
 soldered by holding it over a flame of a Bunsen burner, first passing 
 it through the flame so that it will strike the plate a short distance 
 from the tube, and holding it there until the gold begins to melt. 
 The tube is then drawn back into the flame and held until the gold 
 is thoroughly melted, the tube is soldered all the way across, and 
 the gold is well burned into the platinum. 
 
 If the tube is first held in the flame, it will be found that as the 
 pure gold solder melts, it will jump up over the side and around the 
 t(jp of the tube, but will n(jt unite it at the lap. It is cooled by 
 laying it on a cool surface, such as a file or an anvil. This will take 
 but a moment. It should never be cooled in water, as should this 
 be done, when another mandrel is driven through it, the tube being 
 moist will cause the mandrel to rust and it will be ruined after 
 having been used but a few times. 
 
 The next step is to take the mandrel of the next size larger than 
 the one over which the tube was first rolled and drive it through the 
 tube, having the tube facing towani the operator and the surphis 
 plate extending to the right. The end of the tube is placed on 
 
282 
 
 TUBES AND SPLIT PINS 
 
 the anvil and the mandrel driven through it by tapping with a 
 light hammer until it comes in contact with the anvil (Fig. 511). 
 
 Fig. 511 
 
 The mandrel is then grasped in a pin-vise and the surplus metal 
 trimmed away as close to the tube as possible (Fig. 512). 
 
THE TUBES 
 
 283 
 
 The mandrel being driven thrc)U<:;li in this manner, with tiie lap 
 to the rifiht. allows the Hat side of the scissors to be placed a<iainst 
 the tnbe and thns cnt close to it. The lap is then filed perfectly 
 smooth and flush with the sides of the tube (Pig. 512, aa), so that 
 in rotating it between the fingers, no unevenness is felt. If a ridge 
 is felt along the side, it should be filed off carefully so that the 
 diameter is no greater at that point than at any other. 
 
 Fig. 512 
 
 The end of the tube is then bent over the rounded end of the 
 mandrel by pressing it and working it over with the side of a smooth, 
 flat file, until it is partially closed (Fig. 513). The stretching of 
 the tube over the mandrel will necessarily make it fit so tightly 
 
 Fig. .51.3 
 
 
 J'k;. 51 I 
 
 that it cannot be jnilled off, but by rolling it a little under a smooth 
 file on the anvil, with a little pressure the metal will l)e stretched 
 sufficiently to allow of the mandrel being removed. 
 
 A small square of the same metal of which the tube is made 
 
284 TUBES AND SPLIT PINS 
 
 is then placed on the charcoal block and a small piece of pure 
 gold melted on its surface. The tube is grasped in a pair of pliers, 
 the partially closed end being down and resting on the square 
 of the platinum (Fig. 514). The small blue flame of the blow-pipe 
 is applied and as the pure gold melts and catches the tube to the 
 floor it should be lifted slightly from the charcoal block so as to 
 allow a flame to pass underneath the floor until the pure gold solder 
 has flowed all around, perfectly uniting the tube to the floor. The 
 mandrel is again driven into the tube and placed in the pin-vise, 
 which grasps the end of the tube, the surplus metal of the floor 
 is cut away and the edges filed flush with the sides of the tube 
 and the end slightly rounded. 
 
 When speaking of the size or the number of the tube, the size of 
 the mandrel over which the tube was finished is indicated. Thus 
 a No. 4 tube was first rolled around a No. 3 mandrel and finished 
 on a No. 4. 
 
 The No. 1 and No. 2 tubes are indicated in the teeth having 
 smaller roots, such as the upper laterals and bicuspids, the No. 2 
 and No. 3 for the upper centrals and lower bicuspids, the No. 3 
 arid No. 4 for the upper centrals and upper and lower cuspids and 
 No. 5 and No. 6 for the molars. 
 
 SPLIT PINS. 
 
 The split pin, in order to be effective, must be made of a high 
 fusing, elastic material and rigid enough to withstand the strain 
 to which it will be subjected, and must be an alloy which will retain 
 its elasticity even after being subjected to a very high heat. 
 
 There should be no loss of metal between the halves to weaken 
 it in the least, and it should have practically the same amount of 
 material in it as though it were a solid pin. The solid pin, which 
 has been sawn through the center in order to produce a split pin, 
 is worthless, so far as the lasting qualities of the pin goes, for the 
 reason that a saw cut made through the center of the metal, has 
 cut it away at its strongest part and rendered it very weak (Fig. 
 515). Half-round wire is the best material for making split pins 
 and securing a maximum amount of strength (Fig. 516). For this 
 purpose, platinized gold or clasp wire is the best. 
 
 Iridio-platinum Wire.— Iridio-platinum wire, while it may be a 
 tougher and more rigid alloy than the clasp wire, does not seem 
 suitable for split pins. The writer did considerable experimenting 
 
SPLIT PINS 285 
 
 with this metal, covering a period of two or three years. At first 
 it seemed as though this was the metal best suited for the making 
 of split pins. After a time, however, bridges in which these pins 
 had been used began to be brought to him with the pins broken 
 
 Fig. 515 Fig. 516 
 
 close up to the caps and they were replaced with platinized gold 
 wire. It seemed that the constant springing brought about a 
 recrystallization of the metal which rendered it very brittle. It 
 would break with a clean sharp fracture, showing a very fine grain 
 which jjresented the appearance of fractured hardened steel as of 
 a broken needle. This result followed in almost every case where 
 the iridio-platinum had been used, so that its use was finally 
 discontinued. 
 
 Platinized Gold or Clasp Wire. — Of the various makes of gold and 
 platinum alloys, known as platinized gold or clasp wire, which 
 can be procured from the different dental supply houses, very 
 few are at all suitable for split pins. The majority are too soft, 
 or become so after being subjected to a high heat, and they also 
 have too low a fusing point, very few of them standing a higher 
 heat than that required to melt 18-carat solder. When the heat 
 is raised above this point, the metal loses its elasticity and is apt 
 to be fused together. 
 
 For many years there was only one manufacturer which produced 
 a clasp wire which was suitable for this purpose. Within the past 
 few years, however, other manufacturers have taken the matter up 
 and it is now possil)le to secure other makes of high-fusing and high- 
 grade metal which can be used. It should have a melting point 
 above that of coin gold, and it shoukl be possible to use this alloy 
 as a solder for it without the slightest tendency to fuse, and without 
 any lo.ss of elasticity. 
 
 During a scries of ex[)('rimerits the idea of sweating tlic halves 
 together was tried, but the i)rocess proved a failure. In sweating the 
 parts together, the whole mass of metal was heated nearly to the 
 melting i)oiiit of the alloy but this high heat brought about a molec- 
 ular chaiig«' which reiKiered the metal practically the same as cast 
 
286 TUBES AND SPLIT PINS 
 
 gold, with the result that the pins became quite brittle and were 
 broken in a comparatively short time, necessitating the replacing 
 of them in nearly every instance where they had been used. 
 
 The size of the half-round wire used in making the pins for the 
 different sized tubes, will run from about No. 12 to No. 14, inclu- 
 sive. The wire of which the pin is to be made should, when brought 
 together, be of a slightly greater diameter than that of the inside 
 of the tube, thus giving an excess sufficient to allow for turning or 
 filing them to fit the tubes. The No. 14-gauge wire can be used 
 for the No. 1 tube, and sometimes for the No. 2, the No. 13-gauge 
 for the No. 3 and No. 4 and No. 12-gauge for the No. 5 and No. 6. 
 The measurement should be taken from the bottom of the tube 
 to the floor of the cap and the wire should be bent about one- 
 eighth of an inch longer so that the pin when completed will stand 
 that distance above the floor. 
 
 Fig. 517 
 
 The half round wire is well annealed and is then bent on itself, 
 the flat side innermost, as in the illustration (Fig. 517). It is then 
 again annealed and bent still further over, bringing the end in 
 contact with the flat surface of the wire. It is now grasped in a 
 pair of pliers, at point a, Fig. 518, and held in the flame of a Bunsen 
 burner until it reaches a red heat. The ends are brought together 
 and held until it is chilled slightly, thus removing the spring and 
 bringing the ends in contact for about one-eighth of an inch. The 
 contact should be long enough so that when it is soldered and the 
 pin completed, the soldered portion will come beneath the floor 
 of the cap. The pin and the point of contact is longer in the case 
 of an inlay and tube and split pin, as already described. 
 
 The part in contact is then fluxed and a small piece of coin gold 
 placed on the flat side of the wire in contact with the overlapping 
 end, point b, Fig. 518, and the coin gold melted with the blow- 
 pipe and drawn through sufficiently to unite it. Care should 
 be takeii not to use an excess of the coin gold as solder, as 
 by so doing the pin may be very materially weakened. If a large 
 
SPLIT PINS 
 
 28i 
 
 amount of solder has been used, it will draw through into the 
 loop, leaving a large bulk of the gold extending beyond the point of 
 contact (Fig. 519, a). The result is that when this is hammered 
 or forged down, so that the two sides of the pin are in contact, the 
 large bulk of the coin gold has been hammered into the sides of 
 the platinized gold wire, so that both sides are partially cut through, 
 as in Fig. 520. This will, of course, weaken the pin at this point 
 and it will \ery easily be broken. 
 
 After this pin has been soldered, the extending wire is grasped 
 in the pin-vise and the sides of the pin hammered together, bring- 
 
 FiG. 518 
 
 Fig. 519 
 
 ing the two halves in contact. During the hammering or forging 
 the pin must be kept rotating, thus forging it round as the halVes 
 are gradually brought into contact. If the two halves are ham- 
 mered together without rotating, it will be found that the sides 
 have been flattened, thus making the diameter of the pin in this 
 direction much less than in the direction of the split (Fig. 521), 
 This will render it much more difficult, in fact it will be almost 
 impossible, to make the pin perfectly round, whereas, by rotating 
 it, the halves are brought in contact, at the same time forging it 
 into the desired shape so that there will be little trouble in making 
 the pin fit the tube. After forging, the pin should be annealed. 
 
 Fig. 520 
 
 Fig. 521 
 
 Filing of the Pins. — Fihng is an art. There may be some who 
 will doubt this statement, but it is true nevertheless. To learn 
 to use a file properly retpiires a great deal of practice and some 
 natural ability, and before inidertaking to fit the pin to a tube, 
 considerable time should be de\'oted to working with the file. 
 Of as great importance as the proj)er use of the file is the jjroper 
 method of using the pin-vise, and the dentist should learn to rotate 
 the [)in-\is(' properly. 
 
 Th<" Ix'sl |)in-vise to use for the j)ur])(».se is one which is perfectly 
 round, and which has no set screws, but has jaws of the nature of a 
 
288 
 
 TUBES AND SPLIT PINS 
 
 chuck which will grasp the pin and hold it in line with the pin- vise. 
 The one shown in the illustration (Fig. 522) is the best which can 
 be procured for all work of this character. 
 
 The pin is grasped by the soldered end in the pin-vise, catching 
 it only far enough down to get a strong hold. The pin- vise is held 
 lightly in the fingers of the left hand, the end of the thumb resting 
 
 Fig. 522 
 
 on the top of the pin-vise and the pin on the filing block, as shown 
 in the illustration (Fig. 523). 
 
 The file used for roughing down should be of two or three cut, 
 flat, and about five inches in length, and should be held in the 
 right hand very lightly, the forefinger resting on the face of the 
 file, and over the middle of the pin extending from the pin-vise 
 
 Fig. 523 
 
 (Fig. 524). The pin- vise is then rotated to the right with the thumb 
 and fingers of the left hand. The file is passed lightly over the 
 
SPLIT PINS 
 
 289 
 
 pill in the opposite direction, very little pressure being used, not 
 much more than the weight of the file itself. The file should be 
 moved only while the pin is rotating, being pushed forward over the 
 pin and lifted from it while the pin-vise is still in motion. If this 
 should not be done, and when the pin has stopped revolving, the 
 file should be still pushed forward, a flat surface would be produced 
 at that point. As previously stated, the finger should rest over the 
 middle of the j)in which perhaps extends one-half or two-thirds of 
 the way across the file (Fig. 524). If the finger is held at the outer 
 
 Fig. 524 
 
 edge of the file, there will be a greater i)ressure at this end of the 
 l)in than there should be, with the result that the pin will be made 
 smaller at the outer end and the sides will not l)e])arallel (Fig. .")2r)). 
 If a ver\- short j)in is being filed, the finger should rest at the 
 extreme inside edge of the hie. The file should not be gras|)ed as 
 would be a baseball bat. If the file is held in the hand ver\ lirnilv , 
 IJie deliejite sense (»f touch is lost and uneoiiseiousl.\- a greater 
 pressure is |)lae<'d on one or the other end of the pin, with tlu^ 
 result that it cannot be made of a luiiform diameter throughout 
 it-, length. When the file is held very lightly, so that it will mo\e 
 
290 
 
 TUBES AND SPLIT PINS 
 
 freely with the slightest pressure of the forefinger, it will find its 
 own level and keep the sides of the pin parallel from one end to the 
 other. 
 
 Fig. 525 
 
 When the pin has been roughed down with the coarse file to nearly 
 the size that is desired, the final fitting and polishing should be done 
 with the finest file that can be procured and afterward it is burnished. 
 For the final finishing, a flat file about five inches in length is 
 used, one side of which is at least as fine as a six cut, and better 
 still if it be a seven or eight cut. The other side is not cut at all, 
 but is perfectly smooth and polished for use as a burnisher. 
 
 With the cut side of the file, the pin is smoothed down until it 
 is very nearly as it should be, fitting the tube snugly. It is then 
 burnished with the smooth side, until the pin becomes perfectly 
 smooth, having a polished surface and fitting the tube easily 
 throughout its entire length. 
 
 The burnishing is perhaps the most important part of the opera- 
 tion of making a split pin, for the reason that no matter how fine 
 the file which is used in fitting the pin may be, it leaves a surface, 
 which, under the microscope, will seem to be very rough, the serra- 
 tions or fine ridges and grooves presenting the appearance of a 
 
6 PUT PINS 
 
 291 
 
 very tine thread of a screw. If the pin should he used without any 
 further finishino;. these serrations, being so \er\' fine, would wear 
 smooth ver\' quickly, thus reducing the size of the pin to that 
 extent and rendering it loose in the tube and making what might 
 be termed an ill-fitting or loose-fitting pin. 
 
 Too much importance cannot be placed on the ])roper fitting of 
 the pin into the tube. The pin should fit the tube easily. If it 
 fits too tightly, it would be difficult when the bridge is waxed in 
 position for soldering to remo\e the outer from the inner parts 
 without springing or distorting it, and it would also require too 
 much force to remove the briflge from the mouth. If the pin goes 
 into the tul)e touching the sides for its entire length it may fit 
 easily, so that it will slide out and in without any great effort to 
 move it. 
 
 If the tube is very long, necessitating a split pin of great length, 
 the end of the pin can remain closed and at any future time, if it 
 should be necessary to spread it in order to give the ])in greater 
 retenti\e power, it can be opened a little in the middle, thus making 
 a long, narrow, elliptic spring (Fig. 52G). If the pin is short, then it 
 is filed oj)en at the end and the end carefully rounded, polished and 
 burnished. 
 
 In filing it oi)en at the end, the file should follow the direction 
 of the split until it is oi)en (Fig. 527), and not across the split. The 
 reason for this is that in filing across the split, as soon as the solid 
 
 (D 
 
 Fig. 520 
 
 Fig. 527 
 
 Fk;. 52.S 
 
 end is filed througii, e\en if a \<t\ fine file is being used, the farther 
 half of the pin is forced awa.\ and a feather edge is turned o\-er 
 on the far side of the inner half and some j)articles of the filings 
 may Ix* forced between the halves, thus spreading the j)in and 
 making it difficuh or preventing it from entering the tulx* (Fig. 
 r)2S). This would necessitate still further filing ;ind consefinent 
 weakening of th<' pin. 
 
292 
 
 TUBES AND SPLIT PINS 
 
 THE WEINSTEIN DEVICES FOR MAKING SPLIT PINS. 
 
 Mr. L. J. Weinstein, of New York, has invented a swaging device 
 to assist in the making of spHt pins. It is of the utmost value, and 
 by its use one is enabled to make a plit pin more quickly and accur- 
 ately than is possible by simply forging and filing (Fig. 529). 
 
 Fig. 529 
 
 
 Fig. 530 
 
 The device consists of a double anvil, octagonal in shape. The 
 two halves are faced off so that there is perfect contact between 
 the two faces, and these are guided to, and held in their proper 
 positions with dowels. From each of the octagonal faces, a hole 
 
WEIXSTEIX DEVICES FOR MAKING SPLIT PIXS 293 
 
 is (Irilli'd toward tlu- ci'iitrr Ix-twccn the liahos, lca.\inu- halt' i-oiiiid 
 grooves of ocpial size in eacli of tlie workinj;' surfaces. Tliese have 
 been reamed and poHshed and the sizes of the holes are a little 
 more than one-thousandth of an ineh larger than the mandrel 
 corresponding in number to the number on the swager (Fig. 530). 
 The half round wire used in making the split pins is a little more 
 than one one-thousandth of an ineh larger than the hole in the 
 swager in which it is to be finished. A draw ])late comes with the 
 outfit, the numbers corresponding with the munbers on the swager 
 and the mandrels (Fig. 531). 
 
 Fig. 5.31 
 
 Although the wire ("elastic" gold, Weinstein's formula) may 
 be purchased in suitable sizes, thus axoiding the necessity of draw- 
 ing, it is well to have the draw plate in ca.se of emergency, as it is 
 essential that the size of the wire u.sed should correspond with the 
 pin it is desired to make. 
 
 Fig. 532 shows a small drawing machine invented by Dr. (\ F. 
 ('. Mehlig, of New York, for drawing wire and tubes. It is a 
 wonderful little machine, and is geared so that a heavy wire can 
 be drawn down with almost no effort. 
 
 Making the Split Pin. — The wire, of a number corresponding to 
 the number of the nuuidrel over which the tube has been made, is 
 bent upon itself, brought in contact as shown in Figs. 517 and 
 518, and .soldered with coin gold. The extending end is then 
 grasped in the pin-vise, the looped end placed in the groove on the 
 top of the anvil (Fig. 5.']3), and the two halves l)roiiglit in contact 
 with a small co[)per or fiber faced hammer. 
 
 In order to bring the two halves of the pin into perfect contact, 
 prior to the final forging, the pin is first |)laced into the swager, 
 with the split Ixing horizontally, and struck once w ith a good sharp 
 blow. If the pin is to be. for exairi])lc, a number .1. the closing is 
 to be done in the nund»cr '.'> hole .\ftcr the pin is closed, it is then 
 
294 
 
 TUBES AND SPLIT PINS 
 
 annealed and first swaged in number 5 hole and hammered with a 
 heavy round-faced rawhide, or fiber-faced mallet, rotating the pin 
 constantly until the two faces of the anvil are in contact. (Siee 
 
 •«t 
 
 Fig. 532 
 
 Fig. 533 
 
 Fig. 534.) It is then annealed and hammered in the number 4 hole, 
 then in the number 3 hole, and when the two faces of the swager 
 are in contact, the pin is quite round, the sides are parallel, and it is 
 slightly larger than the tube, just enough to allow for finishing. It is 
 
WEIXSTEIX DEVICES FOR MAKING SPLIT PINS 295 
 
 Fig. 534 
 
 m 
 
 I'KJ. .Vi') 
 
296 
 
 TUBES AND SPLIT PINS 
 
 then annealed again and finished with a fine file and a bnrnisher 
 as has been described or it can be burnished on the lathe. 
 
 Finishing the Split Pin on the Lathe.^ — It is necessary to have a 
 chuck of suitable size and kind to grasp the pin firmly. It is then 
 brought down with a very fine file until it will just enter the tube 
 tightly. The filing can be done more easily and perfectly if the 
 under surface is supported by a very fine file on an instrument with 
 a smooth flat surface, as shown in Fig. 535. The burnishing is 
 done with another device of ]Mr. Weinstein's, which consists of two 
 hinged, hardened, and polished plates, one of which is grooved to 
 receive the pin (Fig. 536). The two plates are brought together, 
 
 Fig. 536 
 
 the lathe run at full speed, the burnisher being moved outward 
 and inward on the pin (Fig. 537), this giving it a smooth and 
 highly polished surface. 
 
 While still in the lathe chuck, it is polished with fine crocus cloth 
 and reburnished. The pin is then opened at the end, and rounded 
 in the manner already described (Fig. 527) or left closed in a long 
 pin. (See Fig. 526.) 
 
 The split-pin swager illustrated was originally made with eight 
 
ANOTHER METHOD OF USING TUBE AND SPLIT PIN 297 
 
 grooves hotwrni the two halves to pr()\i(K> for the six i)ins accord- 
 ing to the stul) steel luaiulrel sizes, .():)S inch to .OTf) iiicli. and 
 two extra ii;rooves for the ])reliininary swa.uiiig (of No. (i pin), it 
 has l)een found advisal)le, however, to reduce the number of the 
 
 Vir.. .-,;J7 
 
 grooves, mandrels, etc., for l)oth the swaging device and paralleling 
 device and the various accessories and the completed device, both 
 for paralleling and swaging now furnished are standardized for 
 four sizes, as follows: No. 1 equals O.OfiO inch; No. 2, 0.004 inch; 
 No. 3, 0.068 inch, and No. 4, 0.072 inch. 
 
 The split-pin swager, burnishing clamp, fiber-faced mallet, draw 
 plates for l)oth wire and tubing and accessories, such as files, etc., 
 are manufactured by the Dental Ftilities Co., of New York. 
 
 ANOTHER METHOD OF USING THE TUBE AND SPLIT PIN. 
 
 There are cases where the ordinary way of using the tube in th<; 
 root with the split pin attached to the bridge is not i)ractical and 
 it is necessary to devise some other method. In some eases a 
 eom|)lete re\<TsaI of this type of attachmenl is indicated, using 1 he 
 
298 TUBjEIS ANb SPLIT PINS 
 
 split pin on the inner cap attached to the root, while the tube 
 is imbedded in the bridge. There are times where the roots stand 
 on such divergent angles that it is not possible to insert tubes to 
 a sufficient depth to give retention and have them parallel, and 
 it is in such cases that the reversal of order is more frequently 
 indicated. Take for example two cuspid teeth in the lower jaw, 
 standing as represented in Fig. 538. 
 
 In a case of this description, the roots are prepared in the same 
 manner as when they stand in a normal position, with the exception 
 
 Fig. 538 Fig. 539 
 
 that the mesial or approximal sides are cut well away, as in Fig. 
 539, in order that the bands may be adjusted with their sides nearly 
 parallel to each other. The labial and lingual sides are trimmed, 
 but it will not be necessary to trim the distal sides, as the inclina- 
 tion of the roots is such that the band will hug tightly at these 
 points. 
 
 The bands are then fitted, the roots cut down to their proper 
 level, and the canals enlarged to receive a strong post. Posts are 
 then placed in the canals, extending well above the bands and a 
 plaster impression taken with bands and posts in position as in 
 Fig. 540. 
 
 A model is then made and the work from here on is done entirely 
 on this. The bands cut flush with the top of the stump and the 
 floor of No. 28-gauge coin gold is sweated to them. 
 
 The pins are made from half round platinized gold wire, the same 
 as the ordinary split pin, and being soldered for about three-eighths 
 to one-half an inch, leaving them open for about one-quarter of an 
 inch from the upper end. The pins are then fitted to the tubes 
 which have previously been made and should be of about a No. 3 
 or No, 4. 
 
 Openings are then made through the floors of the caps to fit the 
 pins tightly and the floors polished. The upper ends of the pins are 
 then grasped in the pin-vise so that they are clutched just below 
 
ANOTHER METHOD Ol<' iSlX'U TlbE AND SPLIT PIN 299 
 
 the point \\lu're tliey are soldered and are bent so that the l)end 
 will come just beneath the floor and wlien they jiass through the 
 floor the>' will stand parallel with each other (Fig. 541). 
 
 Fig. .540 
 
 Fui. .541 
 
 A little wax is placed around the pins where they pass 
 through the floors, the wax being very hot and afterward every 
 particle of wax should be scraped from around the pin and oft' 
 the floor so that no solder may draw through at this point. A 
 little impression is then taken, in investment material, of each of 
 the caps with the pins in place. The caps and pins will probably 
 come away with the impression. If not, they are removed from 
 the stumps and carefully placed in the impression. The investment 
 impressions are dried out, the pins fluxed on the inside of the caps 
 where they pass through the floors and they are soldered to the 
 floors from the inside with 2()-carat solder, as shown in Fig. 544. 
 
 Vic. .542 
 
 Fi(i. .54.S 
 
 Fi<;. .541 
 
 They are thus soldcrcrl from the inside, so that no solder ma\' 
 flow on the outside of the floors of the ca])s or around the pins and 
 thus interfere with the fit of the tubes and outer caps. 
 
 Making the Outer Cap. In making an outer cap for this style of 
 abutment, a floor of No. 2S-gaugc coin gold is used and the hole 
 is made so as to fit the pin easily, but not loosely. It is then cut 
 flush with the sides of tlw inner cap and tin- lialf-band fitted to it 
 and soldered as in tlic making of a caj) of the regular txpe, after 
 wliicli it is replaecd on tlic inner cap (Fig. 54;i). 
 
 Tlic tube, uliich -^lioiild be the exact length of tlic pin and close<l 
 
300 TUBES AND SPLIT PINS 
 
 at the upper end, is next placed over the pin and is made so that it 
 will set down closely to the floor all around and is waxed to it with 
 a hard tough Avax. It is then removed, a little investing material 
 carried into the tube and a small iron wire inserted, letting it extend 
 about one-quarter of an inch below the floor, as in Fig. 544. This 
 will hold the tube in place so that it will be impossible for it to shift 
 its position and it is imbedded in the investment (Fig. 545). The 
 tube is soldered to the floor with 21- or 22-carat solder. 
 
 After cleansing and drying the facing is ground to the floor of 
 this cap (Fig. 546) and when the bridge is invested for soldering, 
 a small wire is inserted into the tube and imbedded in the invest- 
 ment the same as when attaching it to the floor, to prevent it from 
 shifting. 
 
 Fig. 54.5 Fig. 546 Fig. 547 
 
 In soldering this crown, it is necessary that the tube should be 
 completely imbedded in and entirely covered with the solder which 
 should be of 20 carat. It is rarely that the proper lingual contour 
 of a cuspid crown of this type can be obtained as the tube is of such 
 bulk and must have sufficient length to give it retention, so that the 
 crown will necessarily be bulky on the lingual side (Fig. 547), 
 often presenting something the appearance of a lower first 
 bicuspid. 
 
 These crowns may at times be used in any of the teeth anterior 
 to the molars and form practically as good an anchorage as a crown 
 of the regular type, but as they are more difficult to make they 
 are not used except where especially indicated. 
 
 In cementing these caps, it is not possible to cement them in the 
 way in which the caps of removable bridges are ordinarily cemented, 
 as the inclination of the pins is such that they could not enter the 
 roots. In this type it will be necessary to set the crowns separately, 
 using only as much cement as is required to set them properly and 
 then placing the bridge over them immediately, before the cement 
 has had time to set, thus insuring their being perfectly seated in 
 their proper position. The outer caps should be coated with cocoa- 
 butter so that if a little of the cement should get between the outer 
 and inner caps, they could be readily separated. 
 
CHAPTER XIV. 
 
 METHODS OF USING PORCELAIN CROWNS WITH CAST 
 BASES IN REMOVABLE BRIDGE-WORK. 
 
 With the ad\ent of the casting process, came the more general 
 use of all porcelain crowns for bridge-work, in place of the facings 
 or veneers which had heretofore been used to partially hide the 
 mass of gold of which the bridge proper was constructed, thus 
 producing much more artistic effects than was possible by the old 
 methods. 
 
 The casting process, however, has its limitations, and is very 
 far from being a "cure-all" for everything. There are far fewer 
 cases where this process is really indicated than many seem to 
 think. Those who expected to use it to the exclusion of every 
 other method have doubtless found themselves badly mistaken. 
 
 In long bridges, where great strength and stability are essential, 
 the casting process is not indicated, as the cast bridge is far inferior 
 in strength to a soldered l)ridge, and the shrinkage of a large piece 
 in casting is such as to render it unsuital)le where great accuracy 
 is required. In some instances, it is much more suitable for fixed 
 bridges than removable, and then again, the rex'crse mav be true. 
 Good judgment nnist be used in its application, and it must be 
 used only where indicated to avoid disappointment. 
 
 In a large number of instances, the casting ])rocess may l)e used 
 for certain parts of the work, but it is very rarely that it should 
 be used throughout the whole operation. 
 
 The dcj)th of the })ite is a ver\' essential factor in using jxjrcelain 
 crowns in bridge-work. This nnist be great enough to allow suffi- 
 cient room for a good substantial base in order to gi\'e strength 
 and stability to the bridge. A very close bite is altogether unsuit- 
 able for the use of crowns, and where we ha\'e this eonditicui, we 
 must resort to the older niethods In order (o produce results which 
 will be satisfactory and <lurable. 
 
 I'oreelain crowns are especially ap|>li<iil»le in (lie anlerior part of 
 the mouth, as all i)orcelain crowns present a nuich more life-like 
 an<l natural aj)i)earancc than does a facing which is backed with 
 
302 PORCELAIN CROWNS AND REMOVABLE BRIDGE-WORK 
 
 metal, although there are many cases where it is impossible to get 
 shades which will answer the purpose. The incisal edges of -the 
 teeth, especially, are frequently lacking in that clear translucency 
 which is to be noticed in most of the natural teeth, and it is often 
 necessary to resort to the backed facings, even when making 
 restorations in the posterior part of the mouth, but the bicuspids 
 and molars are much more easily matched than are the incisors. 
 
 In making a bridge of this character, the crowns of any of the 
 diflPerent manufacturers which come nearest, in mould, shade, 
 and texture, to the requirements of the case may be used. There 
 must be a sufficient depth of bite to allow of every crown having a 
 base deep enough to give strength and stability to the bridge. 
 
 It would be well to first consider a bridge for the anterior part 
 of the mouth, restoring the six anterior teeth, using the cuspid 
 roots as abutments. The caps, together with the tubes and split 
 pins, are made as has been previously described, and an impression 
 for the saddle taken, the model and dies prepared, and the saddle 
 swaged of No. 32-gauge soft platinum. Unless the bite is extremely 
 long, and there has been considerable resorption, the saddle should 
 extend only to about half or two-thirds of the way over the ridge 
 labially, as at least one-third of the base of the crowns, labially, 
 should be made to fit closely on the ridge. The saddle is reinforced, 
 with coin gold, adjusted to the ridge and the relation of the saddle 
 to the caps taken with the saddle under pressure. The impression 
 and bite being taken together. 
 
 The model is then prepared and the crowns are ground in posi- 
 tion. The cuspid crowns should first be fitted and ground so as to 
 touch the labial third of the floor of the outer caps, clearing enough 
 lingually to afford a strong base and the lingual and mesial sides 
 are beveled, as in the case of single crowns in Fig. 548. 
 
 Fig. 548 
 
 The incisor crowns are then ground in, the model having been 
 scraped somewhat to allow of their setting closely against the 
 
MAKING THE BASES 303 
 
 gum when the bridge i-; completed. They sliould fit the plaster 
 model on the labial side, but should be ground to clear the saddle 
 well lingually, so as to get a sufficient depth of metal for strength, 
 as in Fig. 549. 
 
 The lingual and mesial and distal sides of the base of the crowns 
 are then beveled the same as the cuspid crowns have been, and 
 after the crowns have all been arranged in a satisfactory manner, 
 they are waxed in place. 
 
 Making the Bases. — In a large number of bridges of this character, 
 which are made for the anterior part of the mouth, it will be found 
 that the lingual contour of the crowns is not sufficient to give the 
 necessary strength after they have been ground in position, and 
 where such is the case, it is necessary to first build them up on the 
 
 J'iG. .550 Fig. 5.51 
 
 lingual sides before grinding (Fig. 550). This is especially true of 
 the crowns made by some manufacturers. If the base of the crowns 
 are ground away lingually as much as is necessary, it will leave 
 practically no hold for the post, and very little bulk of i)()rcelain 
 back of it to give the necessary strength to the crown, as will be 
 seen in the illustration (Fig. 551). It will also decrease the labial 
 lingual de})th of the base of the crown by about one-third. This 
 will apply both to the cuspids and to the incisors, and it is very 
 rarely that the writer uses these crowns without first building out 
 the contour considerably in porcelain on the lingual side before 
 grinding. Then, too, the shapes of the cuspid crowns are scarcely 
 ever normal, the lingual surface being decidedly concave and 
 more the shape of an incisor, while it should be thick and heavy, 
 as shown in Fig. 552, indeed often being slightly convex rather 
 than concave. 
 
 The enamel on the lingual side of the crown should be first 
 ground away with a fine carborundum or an emery disk, so as 
 to afl'ord a better attaehment for the j)oneluin which is to l)e 
 baked on. The ponclain is then built in lieavil\-, us in Fig. 510, 
 enough being added so that when the base of the crown is ground 
 away, as in Figs. 5 IS mikI 510, the labial and lingual diameter 
 
304 PORCELAIN CROWNS AND REMOVABLE BRIDGE-WORK 
 
 is great enough to cover the entire cuspid cap, and in the incisors 
 so that after grinding, the Ungual side will be extended so that the 
 pin will come up near the center of the crown or, better still, a little 
 labially, the bulk of the porcelain being on the lingual side. 
 
 After the crowns are properly ground, it will generally be found 
 
 that the post-holes are too shallow to give support and they 
 
 should be deepened enough to allow of the use of a 
 
 post of sufficient length to give ample support. This 
 
 may be done by using a copper wire in the engine and 
 
 deepening the hole in the crown with carborundum. 
 
 Carborundum and oil may be used, or what is still better 
 
 powdered carborundum and glycerine, the glycerine 
 
 forming a good vehicle for carrying the powder, and 
 
 at the same time being much more easily washed away, 
 
 as the glycerine, mixing freely with water, will permit of 
 
 Fig. 552 the cavity being washed out quickly with clear water, 
 
 while in using the oil for carrying the carborundum, 
 
 which will cut no better than glycerine mixture, it is necessary to 
 
 wash thoroughly with soap and water. 
 
 Making Copper Drills. — Copper drills are easily made. A piece 
 of wire of the same size and of about the same length as the shank 
 of the engine burs is .secured and one end ground or turned down, 
 for about one-half an inch, to the size which the holes in the crown 
 are intended to be. They are then placed in the hand-piece and 
 used in the same manner as an engine drill. 
 
 The point of the copper drill is dipped into the carborundum 
 and glycerine and entered into the hole in the crown and the engine 
 run rapidly, the point of the drill being moved up and down so as 
 to keep the carborundum and glycerine constantly in the bottom 
 of the cavity. This should be continued until the cavity is of a 
 sufficient depth. The end of the drill should be perfectly flat, 
 or still better slightly countersunk, so that it is enabled to hold 
 the grinding powder better. It may be countersunk by running it 
 rapidly and holding the end against the end of a small drill or bur. 
 A number of these drills may be made and kept on hand and 
 recountersunk from time to time as the ends become rounded, for 
 when the drills are so worn they do not work well, the carborundum 
 and glycerhie working on the side rather than at the point of 
 the drill. 
 
 The crowns being finally ground in position, a wall of plaster is 
 built up on the labial side, extending to within a thirty-second or 
 
.l/.lA7.Vf,' COPPER DlilLLS 
 
 :;():) 
 
 a sixteenth of an ineli of the ineisal ed,i;e, as in Fig. 053. Tlie next 
 step is bnikling np of the bases in wax, preparatory to casting. 
 
 Fig. 553 
 
 The greatest difficulty with which the operator lias to contend 
 in making these bases is due to the contraction of the cast metal 
 on cooling. The result is that the crowns do not fit as they should, 
 and there is more or less cutting, trimming and fitting to do, before 
 they will go in place, and not infrequently it is even necessary to 
 do the work over again, and perhaps even then the desired result 
 will not be attained. 
 
 The method has been tried of first burnishing or swaging pure 
 gold over the bases* of the crowns and then waxing up and casting 
 on to the pure gold. This has perhaps improved the matter some- 
 what, but still it is very rarely that it has been possible to secure 
 anything like a perfectly-fitting base, especially if the crowns are 
 of an\' considerable size, for with the hirger castings there is a 
 proportionately greater amount of shrinkage. 
 
 One method of overcoming tliis difficulty is that of building out, 
 or cnhuging, the base of the crown before waxing, in order to make 
 up for the shrinkage of gold. After some experimenting, a ])hin 
 was devised, which, while not entirely overcoming the difficulty 
 in every instance, probably due to faulty technic, has, in the 
 majority of cases reduced the trouble to a mininnnn. The method 
 floes not do away with the shrinkage of the gold, for that is an 
 inherent property which nothing can overcome, but by it the 
 o[)erator may counteract or make allowiiiice for this contniction 
 of the metal on cooling. 
 
 Tin; method of procedure is as Inilows: Tin foil, of \arying 
 thicknesses, according to the si/e (»f the crown which is to be used, 
 is burnished or swaged over the crown base, in rcidity first making 
 20 
 
306 PORCELAIN CROWNS AND REMOVABLE BRIDGE-WORK 
 
 a base of this metal, letting it extend just a little above the beveled 
 edge of the crown, as in Figs. 554 and 564. 
 
 The tin foil base is then lubricated with cocoa-butter, and the 
 wax base is built over the tin foil, the lubricated surface allowing 
 of its easy removal. The size of the base of the crown 
 has, of course, been increased the amount of the thickness 
 of the tin. Allowance for the shrinkage has thus been 
 made so that when, the crown is placed in the casting 
 Fig. 554 it fits vcF}^ closely, and if the technic has been carefully 
 carried out there will be little or no trimming to be done 
 after casting. The thickness of the tin foil is varied according to 
 the size of the crown, the largest of course requiring the heaviest 
 foil. Three sizes are used, the first being about .004, the second 
 .006, and the third .008 of an inch in thickness. The burnishing 
 of the foil over the bases is very quickly and easily done. The 
 lighter foil can be pressed nearly to place with a piece of soft rubber 
 and the wrinkles at the edges smoothed out with the thumb nail 
 or a piece of orange wood. With the heavier foils a piece of orange- 
 wood and a small burnisher are all that are required to secure the 
 close adaption which is necessary to insure a perfect-fitting base. 
 
 In making the bases for a series of crowns for a bridge, it is not 
 advisable to cast them together in one piece. The obvious reason 
 for this is that if the bridge be of any considerable length, the 
 shrinkage would be proportionately greater in that direction, so 
 that it would be necessary to grind the crowns on their approximal 
 surfaces, before they would go into position on their bases. This 
 would result in shortening the body of the bridge, and leaving a 
 space at the extremities between the crowns and the adjoining 
 teeth or the abutments. The best method is to cast the bases sepa- 
 rately, and in no instance should more than two bases be cast 
 together. The casting of each base separately, and afterward 
 uniting them does away with the shrinkage which would otherwise 
 take place. 
 
 The casting of the bases for abutment crowns may be done 
 directly on the caps, or they may be cast separately and afterward 
 soldered to the caps, and the operator may choose whichever manner 
 he wishes, although the latter method is perhaps preferable at 
 times in removable work, as there is less danger of disturbing the 
 accuracy of adjustment between the outer and the inner caps. 
 
 The same method of procedure obtains where a saddle is used 
 as an auxiliary support to the abutments and the crowns mounted 
 
MAKING COPPER DRILLS ;5()7 
 
 on this saddle. If the saddle is small, as it would be in the case of 
 a restoration of a single tooth, and if there is not great depth between 
 the occluding teeth and the saddle, the crowns are ground so as to 
 leave sufficient space for the base (Fig. 555) and then be\eled as 
 in shown Figs. 555 and 556. The crowns are tinned and lubricated in 
 
 !• iG. .55.5 Fig. o56 Fig. 557 Fig. 558 
 
 the manner described, but the saddle is left perfectly dry and clean. 
 The wax is then flowed between the bases and the saddle and care- 
 fully car\-ed to represent the gum. The sprue wire is attached to 
 the lingual side, and the crowns are remo^•ed from their bases 
 as in Figs. 557 and 558. A little space on the sides of the saddle 
 is left exposed and free from wax so that it may be caught and held 
 firndy in the investment for casting. After investing, it is cast 
 in the usual manner with coin gold. 
 
 After the casting has been made and cleansed, it is waxed to the 
 abutment cap or caps, as the case ma\' })e, and invested prepara- 
 tory- to soldering the base and saddle to the cai)s. The inside of 
 the bases are well c()\ere(l with whiting so that no solder may flow 
 in and destroy the fit of the crowns. The piece is then heated up 
 and soldered with 20- or 21-carat solder. Where the bases are cast 
 separately and afterward soldered to the saddle or the caps, both 
 the saddle or caps and the tinned base of the crowns are first lubri- 
 cated. A little of the inlay wax is then pressed into the hole in the 
 base of the crown to serve as a post and trimmed off so that it is 
 only a little more than flush with the base. 
 
 The crown is held in position on the model b\- the wall which 
 is made for this purpose, and the inlay wax is flowed over the caps 
 or the saddle between it and the crown. The wax should be used 
 (juite hot so that it will attach itself to the wax post in the base. 
 The space between the cap and base is well filled in, leaving it 
 perhaps a little more than flush with the sides of the crown, covering 
 the beveled edges well. It is then carved and the sprue wire 
 attached to the lingual si<lc. The crown is then carefulh' lifted 
 
308 PORCELAIN CROWNS AND REMOVABLE BRIDGE-WORK 
 
 away from the wax base and the wax base removed from the cap 
 or saddle. 
 
 Before waxing, it is well to make a couple of little pits or slight 
 grooves at different parts on the cap or saddle so that when the 
 base is cast, it will be positively seated in its proper place (Fig. 559). 
 On the cap a slight countersink with a bur or drill may be made in 
 the top of the post and another at some point near to it and on the 
 saddle at any place where the platinum has been covered with coin 
 gold. After the bases have been cast and cleansed, they are adjusted 
 in position on the saddle or caps, and invested, being held in place 
 by a little wire clamp. The top of the post is slightly countersunk 
 and the end of the wire clamp is pointed. 
 
 Fig. 559 Fig. 560 Fig. 561 
 
 In the case of a saddle, the wire clamp extends from the top of 
 the post to the under part of the saddle directly beneath it, just 
 clearing it on the buccal side, as shown in Fig. 560. Where the 
 base is to be soldered to the half cap, the wire extends from the top 
 of the post to the under part of the floor, and as nearly on a line 
 with the crown post as possible, as shown in Fig. 561. 
 
 The investment should be very light and just fill the under side 
 of the cap or saddle, having only enough to hold the parts in posi- 
 tion, leaving the whole of the upper parts exposed. This facilitates 
 the thorough heating-up of the piece and the solder is easily drawn 
 through from the lingual side, uniting the bases to the saddle and 
 to each other. The crown side of the bases should be well coated 
 with whiting or some antiflux, so that there is no danger of the 
 solder flowing over this surface. 
 
 The solder is used in strips, and is fed from points a in Figs. 
 560 and 561. The invested pieces are heated up very highly and 
 the solder drawn entirely through from these points. It may be 
 flushed over the lingual sides as much as is required. Twenty or 
 21 -carat solder is used for this purpose, but the 21 -carat is to be 
 preferred, as it is not likely to be disturbed when a lower carat is 
 used in a subsequent soldering operation. 
 
DEEP SADDLE 
 
 ;'>09 
 
 Deep Saddle. — Wliere there Jias heeii a c-onsiderahlc aniuunt i)f 
 resorption and there is a great (lei)th between the occhiding teeth 
 and the ridge, it wonld make these bridges unneeessarily and unde- 
 sirably heavy to l)uild solid bases extending from the 
 crowns to the saddle. This will appl.N- where there is 
 to be an abutment at each end of the bridge, and 
 also in extension saddles which are anchored only 
 at one end, as in the lower jaw where the molar's 
 are missing. The bases may be made in the form of a ring, co\ering 
 the beveled edge and extending only far enough underneath to form 
 a positive seat for the crown, as in Fig. 562. 
 
 After the crowns have been ground in place, they are fastened 
 in position with sticky wax and plaster is flowed over the occlusal 
 surfaces extending over the buccal and lingual sides for a short 
 distance and engaging the plaster teeth or model at either end, as in 
 
 Fig. 5iy.i 
 
 Fig. 563. The lower edges of the crowns are beveled, as Figs. r>i]') and 
 556, so that the bases may extend over the gingival edges, gripi)ing 
 them tightly, thereby aflording a firm seat and minimizing the 
 possibility of a fracture. They should be beveled so that the line 
 of the bevel on the buccal and lingual sides will follow the natural 
 curve of the occlusal surfaces so as to ])resent a symmetrical ap])car- 
 ance which would not !)(• the case if they were beveled carelessly, 
 one being shorter than the other. This can be done very easily, 
 as the occlusal ends of the crowns resting in the plaster, expose the 
 entire body of the crown, the operator can plainly see what he is 
 doing and nothing is left to guess work. 
 
 The })ases of the crowns are then tinned in the manner already 
 described and slio\ilil be made sotliex will barely touch mesially and 
 distalK' and arc cauglit witli very little stick\ wax (Ui the buccal 
 
310 PORCELAIN CROWNS AND REMOVABLE BRIDGE-WORK 
 
 and lingual sides (Fig. 564, a and b) . If there is a porcelain crown on 
 the mesial abutment, the base of this should be made and attached 
 to the cap. The other bases are then built on in wax, being waxed 
 against the base on the anterior abutment, but between each of the 
 others, a thin piece of oiled paper should first be placed, completing 
 the base over the first crown, then smoothing the distal side, plac- 
 ing in the waxed paper and then making the wax base for the 
 second crown. When this has been completed, the distal side is 
 smoothed off and another piece of the waxed paper is put in and 
 
 Fig. 565 
 
 the thitd base completed. These bases are all beveled inward, as 
 shown in the illustration, Fig. 565, the reason of which will be seen 
 later. 
 
 The sprue wire is now attached to either the buccal or lingual 
 sides, as in Fig. 566, and each of the bases are cast separately in 
 coin gold. After casting, they are cleaned in hydrofluoric acid. 
 They are now fitted to the crowns and it is rarely that it will be 
 found necessary to do any trimming in order that the crowns may. 
 be properly seated, except to cut out any little bits of the metal 
 which may be there owing to small bubbles in the investment. 
 
 The buccal and lingual sides are then smoothed by beveling 
 downward and inward, as already stated. The occlusal surfaces 
 of the crowns are pressed into the plaster impression and are tacked 
 lightly on the buccal and lingual sides with sticky wax. The cast 
 ring bases are then placed on the crowns and are pressed tightly 
 in place and waxed together with sticky wax, after which they are 
 removed, invested and united with 21 -carat solder. These united 
 bases are then placed back on the crowns and tacked lightly 
 with wax, the whole being suspended from the plaster impression 
 extending over the occlusal surfaces, as in Fig. 563. They are then 
 placed on the model, as in Fig. 563, and the bases are attached 
 firmly to the abutment caps at either end or where there is an 
 extension saddle mesially to the base of the crown serving as an 
 abutment and distally to the saddle on which the last ring should 
 rest, as in Fig. 567. 
 
DEEr SADDLE 
 
 311 
 
 The crowns are tJieu renioNed and the saddle is in\ested for 
 soldering. The under side of the saddle and abutment cap, or caps, 
 are filled with the investment and the remaining investment is 
 placed on the slab and smoothed off, lea\ing it about one-half an 
 
 Fig. 566 
 
 inch in depth. The saddle is then settled lightly in place to the 
 depth of about one-eighth of an inch and some of the investment 
 brought over the saddle at the middle part and under and over 
 the middle ring, but not coming near the mesial or distal ends 
 which are to be united to the abutments or the saddle, as shown 
 in Fig. o()S, a and b. The inside of the exposed rings and the 
 
 Fig. .')68 
 
 inside of the base on the abutment caps are well coated with anti- 
 flux and the investment is heated up and soldered with 2l-carat 
 .solder, enough of the solder being used to unite the rings firmly. 
 
 The .saddle is then clean.sed and thoroughly dried and all the 
 crowns placed in their proper positions ])reparatory to the final 
 step in the making of the bridge. 
 
 The si)acc between the saddle and the ring l)ases of the crowns 
 is now filled with pink paraffin and wax both on the buccal and 
 lingual sides. The wax is then carefully carved so as to restore the 
 natural contour of the gum. .\bout one-eighth of an inch of the 
 edge of the saddle is left exposed and the wax carried up to about 
 midway on the labial and lingual sides of the ring ba.ses, as shown 
 in I''ig. ^)V)'). It is then f;irefnll\- smoothed arHJ polished. 
 
312 PORCELAIN CROWNS AND REMOVABLE BRIDGE-WORK 
 
 Impressions are now taken of the carved surfaces, and if fusible 
 metal dies and counters are being used, the impression is made 
 deep enough to serve as a model, but if lead and zinc are to be used, 
 the model is made by pouring into this impression. The face of 
 the model should extend from well up on the sides of the crowns 
 to at least one-sixteenth of an inch below the lower edge of the 
 saddle. (See Fig. 601.) 
 
 The dies and counter dies are made and plates of No, 28 or No. 30- 
 gauge coin gold struck-up and carefully fitted and adjusted to the 
 saddle. The dies should be perfectly smooth and, if necessary, the 
 surfaces should be polished before swaging-up the plates. One of the 
 plates is carefully adjusted in position and held in place with a clamp 
 over the edge of the saddle, and the piece placed in the invest- 
 ment, open side down, leaving the side on which the plate is to 
 be soldered exposed, as in Fig. 569, The investment is dried out 
 and the inside of the ring bases, the underside of 
 the saddle and the outside of the plate, to within 
 about one-thirty-second of an inch of its edge 
 all around, coated heavily with whiting or other 
 antiflux. 
 
 It is then well fluxed between the plate and 
 
 the saddle and also between it and the rings, and 
 
 Fig. 569 -j-j^g parts thoroughly united with solder. The 
 
 solder is best used in strips and should be 20-carat. 
 
 The plate is first united to the ring bases, flushing it from the 
 
 upper edge of the plate to the top edge of the ring, as in point a, 
 
 Fig, 569, 
 
 After this has been soldered, the plate is united to the lower 
 edge of the saddle at point b, Fig. 569, The solder is used in a 
 strip and is fed in along the edge of the saddle between the two 
 surfaces until it has thoroughly drawn through at all points through- 
 out the length of the saddle, uniting the saddle and plate firmly. 
 These extension saddles should not be chilled quickly, as should 
 this be done there is a liability of their springing and becoming 
 distorted. They should be allowed to cool slowly and are then 
 removed from the investment and cleansed. 
 
 The plate for the opposite side is next clamped in position and 
 invested in the same way as for the plate already united. It is 
 then soldered in exactly the same manner as the first, uniting the 
 plate to the ring and afterward to the saddle and after cleansing 
 and drying is ready for finishing. The only points which need 
 
EXTENSIOX SADDLE BRIDGES 313 
 
 to l)e touched with the stone are at points (t a. Fig. 070, wliere tlie 
 
 plate is uniteil to the ring and it sliould he necessan' only to smooth 
 
 this over but a very little unless au excess of solder has lieen used. 
 
 The edge of the plate and saddle at })oints b h, 
 
 Fig. 570, should be smoothed and rounded. It 
 
 will not be necessary to touch the face of the plate 
 
 with the wheels if the dies have been smooth, as 
 
 the whiting or antiflux which has been placed over 
 
 the face should prevent any solder from flowing 
 
 down over it. The bridge is polished as already 
 
 described, following the carborundum wheels 
 
 with fine emery and cuttle-fish disks and afterward touching lightly 
 
 with pumice and then finishing with the rouge. The bridge is now 
 
 ready for the attachment of the crowns. 
 
 The object in making a saddle bridge in this manner, instead 
 of casting what might be called the entire shell, and then uniting 
 it to the saddle, is that the rolled coin gold plates present a per- 
 fectly dense homogeneous mass, the surface of which can be easily 
 polished, and which takes and retains a very high finish, while the 
 surface of a casting is always more or less porous and will not take 
 as high a polish. It is also much lighter and stronger than it could 
 possibly be made by casting. 
 
 The crowns are fitted with posts which extend through the ()])en- 
 ing in the bases into the body of the saddle. These posts may be 
 made from discarded platinized gold split pins, the lower end of 
 which is sj)read a little, as shown in Fig. 570. These posts are 
 first cemented into the crowns. The hollow body of the saddle is 
 next filled with cement, and the crowns put in ])lace and held there 
 under pressure until the cement has hardened (Fig. 570), after 
 which the excess cement is cleaned away and the bridge is ready 
 for the mouth. 
 
 A saddle bridge made in this way presents a most beautiful 
 appearance and does away entirely with the showing of the gold. 
 At the same time a maximum amount of strength with a niininiiini 
 amount of weight has been obtained. 
 
 EXTENSION SADDLE BRIDGES. 
 
 'I'he most difficnit piece of work wliich the crown ami bridge 
 specialist may be calle<l upon to do, and which re(|nires the greatest 
 skill and accuracy in its acconii)lishnicnt , is the making of a satis- 
 
314 PORCELAIN CROWNS AND REMOVABLE BRIDGE-WORK 
 
 factory extension saddle bridge for the lower jaw, restoring the 
 lost molars or molars and bicuspids. A bridge of this character, 
 if it is properly made, will prove as satisfactory as any piece of 
 bridge-work which can be placed in the mouth. On the contrary, 
 if it is not made, fitted and adjusted as it should be, it will prove 
 most unsatisfactory^ and will ruin the abutment teeth more quickly 
 than any other form of denture. Extension saddles should' not 
 be placed in the mouth excepting where the teeth have been out 
 for a long time and the ridge has become well resorbed, and the 
 tissues are well hardened. It is rarely that they should be used 
 unless the teeth have been out for a year or more. 
 
 In almost every case, there should be at least two anchorages, 
 either two bicuspids, or a cuspid and bicuspid, although there are 
 cases where the alveolar ridge is very pronounced and is very hard, 
 especially if a partial plate has been worn for a number of years, 
 where a single anchorage might be sufRcient. 
 
 When a mouth is in the proper condition for a bridge of this 
 character, the top of the ridge is very hard, in fact there is but 
 little thickness of soft tissue over the bone on the top of the ridge, 
 and this hard ridge will not be much more than one-sixteenth of 
 an inch broad, the tissues thickening gradually on either side as 
 they leave it, as in Fig. 571. 
 
 Next to the proper preparation of the abutment teeth or roots, 
 and accuracy in making and fitting the abutment crowns, the 
 success of a bridge of this kind depends upon the perfect adaptation 
 of the saddle to the ridge. 
 
 It is usually best to first make the abutment caps or crowns. 
 If they are to be telescope crowns, then these crowns should be 
 made and articulated, and also connected together, making sure' 
 that the abutments are parallel. If they are to be porcelain, or 
 porcelain faced crowns, the entire inner caps are made and paral- 
 leled, and the impression taken of these. A model is prepared and 
 the outer half caps with the split pins are made and united together. 
 These, or telescope crowns, if they are to serve as the abutments, 
 should be in position on the roots when the impression for the 
 saddle is taken. 
 
EXTENSION SADDLE BRlDdES 
 
 -.ni-y 
 
 Taking the Impression and Making the Dies and Counter Dies. — 
 The next step is to secure an accurate impression. The writer has 
 obtained excellent results by the following method: 
 
 An impression of the ridge is first taken in modeling compound, 
 using a sheet of the compound about one-quarter of an inch thick 
 and not softened too much. This is passed well back over the 
 abutment teeth and ridge and pressed down at the back and on 
 each side with the fingers so as to secure as good an adaptation 
 as is possible. It is then removed from the mouth and chilled. 
 This modeling compound impression is used as a tray for taking 
 the plaster impression. The plaster is mixed fairly stiff so that it 
 will press hard on the soft tissues. This composition tray is filled 
 with plaster in the usual manner, placed in position, pressed down 
 firmly, and so held until the plaster has well hardened. 
 
 A good impression ha^•ing been obtained, the model is then 
 made from it. It should be of good depth, at least one inch at the 
 shallowest part, so that there will be no chance of the die springing 
 or breaking when swagging the saddle (Fig. 572). 
 
 Fi<;. .572 
 
 The model having been prepare! , the outline for the saddle 
 should be marked upon it. The saddk- should be broad, and 
 should be carried well over the ridge both l)uccally and lingually, 
 so as to have as wide a bearing on the ridge as it is possible to 
 get for the wider the bearing which the saddle has, the greater 
 will be its usefulness to the wearer. 
 
 The edges of the saddle should be turned up somewhat, .so that 
 it will present a thick, rounded surface to the soft tissues, and 
 will not cjit or injure thciii. \ nuu-h broader saddle can be worn 
 with comfort by having the edg<!S well nduidcd, than would be j)Os- 
 
316 PORCELAIN CROWNS AND REMOVABLE BRIDGE-WORK 
 
 sible if the edges were left fairly sharp. These edges, when the 
 bridge is completed, should be at least as thick as a No. 16-gauge 
 wire. In order to turn the edge of the saddle, the model is built 
 up with wax as shown in Fig. 572, before die and counter die are 
 made. This die and counter die may be made of zinc and lead 
 or of fusible metal throughout. The waiter prefers the latter 
 because of the absence of contraction on cooling, and also on 
 account of the ease with which it is manipulated. 
 
 The Saddle. — The saddle is swaged of soft platinum of No. 
 32 or No. 34 gauge. Platinum is always prefered wherever a 
 saddle is used, as the tissues take more kindly to this 
 metal, and it will keep a clean polished surface even 
 better than will pure gold. Then, too, higher grades 
 of solder may be used than would be possible with 
 pure gold. The saddle should be large enough to 
 allow for the edge being turned up all around (Fig. 573). The 
 little swaging mallet shown in Fig. 574 is very useful in working 
 down the platinum saddles before swaging them between the die 
 and counter. It has a rawhide peen and will not mar the platinum. 
 The saddle is hammered over the die and can be brought down 
 close enough for swaging easily and in a very short time. During 
 
 Fig 573 
 
 Fig. 574 
 
 the swaging it should be frequently annealed, but should always 
 be cleansed in nitric acid after swaging before trimming or heating 
 it up again. After the fmal swaging, it is again cleansed in acid and 
 fitted to the modeh 
 
 The platinum being very soft is reinforced to strengthen and stiffen 
 it and this is done with coin gold. The underside of the saddle 
 is painted with an antiflux or whiting as is the top of the ridge back 
 to within about one-eighth of an inch of the distal end and also 
 
EX TEX SI ox SADDLE BRIDGES 
 
 317 
 
 at the front where it turns up to meet the aneh()raji;e or ahutnient 
 at that i)oint to wliieh it will be attached (Fig. 575). This is to 
 prevent the gold from flowing over these places and the underside 
 
 Fig. 575 
 
 ^\ 
 
 Fig. 576 
 
 of the saddle. The coin gold is then flowed o\er the exposed }:>arts 
 of the saddle bringing it flush with the turned-up edges of the 
 platinum and distributed as even as possible, as in Fig. 576. After- 
 ward it is made smooth with a carborundum wheel. The flowin<r 
 of the coin gold over the platinum will have distorted it somewhat, 
 so that it will be necessary to swage it again and after this has 
 been done, it is again cleansed in the acid and is ready for adjust- 
 ment in the mouth. 
 
 The teeth which are to serve as abutments have already been 
 prepared, and the inner caps made and placed in position. The next 
 .step is that upon which the success of this form of denture entirely 
 depends — the accurate adjustment of the saddle to the ridge. 
 
 The Adjusting of the Saddle to the Ridge. — The front end of the 
 saddle, which is to ctmnect with the abutment, and which was not 
 covered with coin gold is turned back a little so that it will clear 
 
 A 
 
 Fir;. 577 
 
 Fig. 57S 
 
 the abutujcnt when it is in jilace. It is now placed in the nw»uth 
 with tin- forefinger of each hand resting on either side of the sad<lle, 
 pressing it in place and is rocked frr)m side to side. It will be found 
 that it is resting on the top of the ridge fFig. 577j. It is riding on 
 
318 PORCELAIN CROWNS AND REMOVABLE BRIDGE-WORK 
 
 a little ridge of bone not over one-sixteenth of an inch wide, and is 
 not bearing anywhere else. Should this condition not be remedied 
 resorption would rapidly take place, allowing the piece to sag, 
 and bringing the whole strain on the abutments, with the result 
 that within a comparatively short time the roots would be loosened 
 and lost. 
 
 The rocking of the saddle from side to side will give an idea 
 as to the amount of correction which will be needed. The saddle 
 is removed from the mouth and placed on the die. It is then 
 raised off from the die a little and the sides pressed inward to it, 
 the fingers grasping the lower edge of the saddle at points a and a, 
 Fig. 578. It is then replaced in the mouth and tested again by 
 rocking it. Should the saddle still rock a little, it is again removed 
 and the sides pressed still further together. It is again placed in 
 the mouth and tested, and this is repeated until the saddle sets 
 perfectly solid without any rocking and rests comfortably on the 
 ridge. If it is found that the sides have been brought together too 
 much, so that it presses too hard on either side of the ridge, it is 
 again fitted to the die and the operation repeated until the saddle 
 is perfectly comfortable and immovable under pressure. 
 
 Securing the Relation of the Saddle to the Abutments. — The front 
 end of the saddle has been turned back so that it will clear the 
 abutments. After it has been adjusted, it must be ascertained that 
 it still clears the abutment, as should it touch it in the least, it may 
 be pressing against the abutment much more heavily than would 
 be suspected and so be forcing the saddle back out of position. 
 
 Fig. 579 
 
 The next step is to get an impression, securing, accurately the 
 relation of the saddle to the abutment caps. The saddle is pressed 
 firmly into position on the ridge, and held tightly in place with 
 as much pressure as can be brought to bear on it with the thumb 
 or forefinger of the left hand, A saddle on the left side of the 
 
EXTENSION SADDLE BRIDGES 
 
 319 
 
 mouth, is held down witli the thumb, the fingers pressing the 
 underside of the mandible (Fig. 579). Should the saddle be on 
 the right side of the mouth, it is held in place with the forefinger 
 of the left hand with the thumb pressing on the underside of the 
 jaw (Fig. 580). 
 
 The plaster is then mixed in the same maimer as for taking an 
 ordinary impression, but more of the potassium sulphate, or what- 
 
 FiG. 580 
 
 ever may be used to hasten the setting, should be used, as the 
 plaster for this purpose should set very quickly. The plaster is 
 placed in the mouth with the spatula, covering the abutments, 
 and the end of the thumb or forefinger which is holding the saddle 
 in place and also covering the surface of the saddle wherever it is 
 exposed. The saddle should be held very firmly and steadily 
 until the plaster has thoroughly hardened. The impression is then 
 removed from the mouth together with the saddle and abutment 
 caps. These are rei)laced in the impression and attached firml\' in 
 their respective position with sticky wax. The inside of the inner 
 caps are now given a thin coating of pink paraffin and wax so that 
 they can rcadil.v be removed from the model after casting. 
 
 A small model not much more than the width of the saddle is 
 then made. It should be of sufficient depth so that there will 
 be no liability of the model being broken, and after it has sufficiently 
 lianh'ned the caps and saddle are removed and it is trinnned and 
 cleansed of the wax with chloroform. 
 
 The al)Utment cji|)s and saddle are then replace<l on the model 
 and the anterior j)art of the saddle, o\-er which no coin gold has 
 been flowed, is pressed over against the caps and trimmed so that 
 it comes just af)out to the lower edge of the outer caj), should it 
 lie a telescope crown, as in Fig. oSl, and labiallx and lingnally not 
 rpiite to the middle <»f the cap a> (t ii, Fig. 5X2. Should the attach- 
 Micnts be caps with tiibe> and ^plit pins, where facings, or porcelain 
 
320 PORCELAIN CROWNS AND REMOVABLE BRIDGE-WORK 
 
 crowns are used the saddle should be fitted to the lower edge of 
 the half-band and extend part way labially along the floor to a a, 
 Fig. 583. 
 
 Fig. 581 
 
 This end of the saddle is then tacked to the abutments with 
 sticky wax and a piece of iron wire is bent over the occlusal surface 
 or the floor of the caps and carried along the saddle and waxed 
 firmly in position with hard, sticky wax (Figs. 584 and 585). This 
 
 Fig. 584 
 
 Fig. 585 
 
 is to prevent the possibility of distortion when the inner caps 
 are removed and the saddle is being invested. The inner caps are 
 now removed and the saddle with the outer caps attached are 
 invested. The outer caps are filled with investment which should 
 cover the lower edges of the saddle; only a sufficient amount being 
 used to hold the parts in position during the soldering (Fig. 586). 
 
 Fig. 586 
 
 It is then warmed up, the bulk of the wax removed and the 
 whole heated until the remainder of the wax has burned away, 
 
EX TEN SI 0\ SADDLE BRIDGES 
 
 m 
 
 or the wax can be melted out with a stream of boihng water, after 
 which it is cooled slightly and fluxed well between the saddle and 
 the caps. The whole is then heated up and the caps and saddle 
 are united with 21-carat solder, using plenty of the sokler and 
 flowing it heavily over the platinum of the saddle which has not 
 been covered with the coin gold. After it has cooled, it is remo^•ed 
 from the investment and cleansed in acid, and after it has d'ried, 
 it is replaced on the model, with the inner caps in place. It will 
 probably be found that when the caps are pressed in position on 
 the model, that the saddle will be raised somewhat at the farther 
 end (Fig. 587). This is due to the solder, of which a considerable 
 
 Flu. 5S7 
 
 amount has been used, contracting on cooling and thus drawing 
 up the end. 
 
 In order to make up for this contraction, it will be necessary to 
 grasp the abutment caps, and raising the caps and saddle a little 
 off the model, press the distal end of the saddle down, thus spring- 
 ing it back a little at a time until it assumes its proper position 
 on the model. It is now ready for taking the articulation. 
 
 Taking the Articulation. — The saddle, with the inner caps in 
 position, is now jjlaced in the mouth and carefully examined to 
 see that the parts are in proper relation. \Vhen the caps are pressed 
 in place the saddle should remain firmly seated on the ridge, and 
 the api)liance should be jxTfectlx' comfortable to the })atii'nt. In 
 securing the articulation for this j)iece, wax or modeling coin- 
 poimd may be used, as the a|)pliance will probably come away 
 with the imjjression and there will b<! little danger of distortion 
 of the articulation as there might be if it had to be pressed back 
 o\'er a uhmIcI. 
 
 The writer, ho\ve\cr, prclVrs plaster in all cases, as in using 
 plaster there is a certainty that a perrect iirti( iiliition will have been 
 secured. This is taken in the sanif manner as in oilier cases, the 
 21 
 
322 PORCELAIN CROWNS AND REMOVABLE BRIDGE-WORK 
 
 plaster covering the saddle well back, as well as the abutment 
 caps, and taking in two or three of the teeth anterior to it. Some 
 plaster is placed over the occluding teeth and the patient is 
 instructed to close the jaws, the other teeth not included in the 
 impression being examined to see that the occlusion is correct. 
 
 ^Yhen the plaster has hardened, it is removed from the mouth, 
 and the saddle, with the inner caps in place, are replaced in the 
 impression. The inside of the inner caps are then given a coating 
 of pink wax and the saddle and outer caps are waxed firmly 
 in the impression, any under-cuts which may appear in the saddle 
 being filled out with pink wax so that the saddle will draw readily 
 after the model has been made. The model is prepared and 
 articulated in the same manner as for an ordinary bridge. 
 
 After the model has hardened, it is separated from the impres- 
 sion, the saddle is removed, cleansed of wax and is ready for the 
 adjustment of the crowns, or it may be finished in any way that 
 may seem desirable. 
 
 There are many methods of finishing these bridges. The teeth 
 may be attached with vulcanite, crowns of various types may be 
 used or tube teeth, diatoric teeth, or interchangeable teeth — now 
 and again prove very satisfactory. 
 
 Vulcanite Attachment. — Where a vulcanite attachment is used, 
 the attachment of the saddle to the abutment caps must be rein- 
 forced. If telescope crowns have been used, round or half round 
 platinized gold clasp wire may be attached near the occlusal end 
 of the outer caps and passed down to the saddle with three or four 
 loops along its length, to firmly secure the vulcanite to the saddle, 
 as in Fig. 588. 
 
 Fig. 588 
 
 AYhere caps, with tubes and split pins, are used as abutments, 
 a loop of the half-round clasp wire may be run across the caps 
 and back and over the saddle, as in the other case (Fig. 589). In 
 either case, in using half round wire, the rounded side of the wire 
 should be next to the saddle and caps. 
 
EXTENSION SADDLE BRIDGES 
 
 6Z6 
 
 For the attachment of the vulcanite to the sides of the saddle, 
 the coin gold covering is well stippled. This will make a very strong 
 attachment and one which will hold as well as any that could be 
 devised. In stippling, a very sharp-pointed graver should be 
 used, and it should be well and deeply stippled in both directions. 
 
 Fig. 589 
 
 This will make a very strong union, so that the vulcanite cannot 
 be torn away. This will apply where the ordinary vulcanite pin 
 teeth or the diatoric teeth are used. 
 
 Where Facings are Used with a Gold Occlusal Surface. — In mak- 
 ing the bridge where facings are used with a gold occlusal surface, 
 it is better that the facings should not be ground to fit the saddle 
 exactly, but should stand away from it for from one-thirty- 
 second to one-sixteenth of an inch, as in Fig. 590. The object of 
 
 Vui. .390 
 
 Fk;. i>\n 
 
 tiiis will be seen later. It is inijjossiblc to grind the facings so tliat 
 they will fit tlic saddle so perfectly as to prcxcnt foodst nil's or 
 saliva from working in bciicatli tliciii. It makes no dill'crence 
 how nnicli time is spent d(»ing it, and even tliongli (lie joints are 
 njadc \cry close, tlicy will not be so after soldering. The tips of 
 the facings should be liigli cnon;;li to touch tlic lingual surfaces of 
 tlic buccal cusjjs of tlic occluding' tcctli, ;is in V\ii. .')!)() a. 
 
 After tli<' facings ha\(' been ground, tlicy ;irc licid in |)lacc with 
 
324 PORCELAIN CROWNS AND REMOVABLE BRIDGE-WORK 
 
 wax on the lingual side, and a wall of plaster built up on the buccal 
 side nearly to the occlusal ends of the facings, so as to retain them 
 in position after the wax has been removed (Fig. 591). The facings 
 are then removed and the occlusal ends ground off at an angle of 
 about forty-five degrees with the backs or lingual side, as in Fig. 
 590 a, leaving them of sufficient length so that they will clear the 
 occluding teeth by about from one sixty-fourth to one thirty-second 
 of an inch. This angle should be the same on all the facings, and 
 the line on which they are ground should be continuous, one follow^- 
 ing the other as though they had all been attached together and 
 
 Fig. 592 
 
 then ground (Fig 592). It will spoil the appearance of the piece 
 if they are ground unevenly, so that the tip of one is higher than 
 the other, one standing up and the other down and it will look 
 as though the piece had been thrown together haphazard, without 
 care for artistic effect (Fig. 593). 
 
 The facings are then backed with thin platinum, the backings 
 touching or overlapping each other slightly and extending from 
 the beginning of the bevel at the occlusal end to the saddle, which 
 they should touch closely all along, being carried straight down on 
 a line with the backs of the facings (Fig. 592). The pins are then 
 flattened and bent upward or downward, pressing on the back- 
 ings to hold them tightly against the facings. 
 
 Fig. 593 
 
 Fig 594 
 
 The facings are then waxed firmly to the saddle with hard sticky 
 wax, the wax being carried high enough to support and hold the 
 cusps but not flush with the lingual side of the cusps (Fig. 594). 
 
EXTEXSIO.X SADDLE BRIDGES 325 
 
 Cusps. — Solid gold cusps are used, and they are selected and 
 made in the same manner as are the cusps for a shell or telescope 
 crown. The buccal side of the cusps are ground, or filed to a bevel 
 to fit the bevel of the facings (Fig. 594). As each one is fitted, it 
 is waxed lightly in place until they are all in position. 
 
 They are then ground or filed away on the lingual side so as to 
 even them and not have one cusp broader or standing further 
 lingually than the other. They should also be filed on a slight 
 angle so as to follow the line of the lingual side as it will be when 
 it is completed. This will gi\e a broad point of contact for the 
 lingual plate when in position and in finishing there will be no 
 danger of grinding through into the hollow space on the inside of 
 the bridge (Fig. 595). If the cusps were not beveled in this manner, 
 the edge of the cusp coming down as it does to a sharp angle, it 
 can be seen in the illustration (Fig. 59(3) that the point of contact 
 
 Fig. .59.5 Fio. .590 Fk;. 597 
 
 would be but slight and if it were ground off a very little in finish- 
 ing it would break through into this hollow space beneath. If the 
 cusps were overbeveled, or cut under, the efi'ect would be practically 
 the same (Fig. 597). 
 
 After they have been ground and fitted, they are attached firmly 
 with hard, sticky wax, but the wax should not extend to the lingual 
 edge of the cusps. After they have been attached, the small end 
 of the wax spatula is heated a little and pas.sed under the cusp and 
 raised slightly CFig. 594 a), lifting the cusp on the lingual side so 
 that on the buccal side the beveled edge of the cusp and facing will 
 toucli lightly at the tip, but there will not be actual contact at the 
 lower or iiuier side of the bevel. The buccal and lingual sides of 
 the bridge are now ready to be finished. 
 
 Waxing and Carving for the Plates. — The buccal and lingual sides 
 arc covered w itii wax, making the lingual side more than flush with 
 the lingual side of the cusps so as to have plenty of stock for carving.^ 
 The pink paraffin and wax is preferable, as it is fairly hard, is not 
 sticky, and curves nicely. Both sides are then carved to represent 
 tlie natural gums. On tlu' buccal side it should be carried a little 
 uboN'e the lower edge of tlic fiicitigs and well up between tlieni. 
 
326 PORCELAIN CROWNS AND REMOVABLE BRIDGE-WORK 
 
 as in Fig. 59S. On the lingual side, the car\ing is made continuous 
 with the lingual angle of the cusp, as in Fig. 599, and the carving 
 should correspond in depth and breadth to the facings on the buccal 
 side. 
 
 Fig. 598 
 
 Fig. 599 
 
 The carving should be carefully done and the surface of the wax 
 made perfectly smooth, in order to insure the obtaining of a clean 
 die so that when the plates are struck up they will be perfectly 
 smooth and when the bridge is completed, they will require no 
 finishing other than with the pumice and rouge. 
 
 An impression is then taken of each side separately, the plaster 
 being carried from below the saddle to above the gum line and 
 over the heel on the buccal side, as in Fig. 600. On the lingual 
 
 Fig. 600 
 
 Fig. 601 
 
 side, the plaster is carried above the cusps and below the edge of 
 the saddle (Fig. 601) and far enough over the heel to meet or overlap 
 the impression from the buccal side. 
 
 If zinc and lead dies and counter dies are to be used, a model 
 should be poured into the plaster impression, as owing to the 
 shrinkage of the zinc it is desirable that the face of the die should 
 present the face of the carved facings and not the reverse side. 
 If, however, fusible metal is used for the die and counter, the 
 impression may be made deep enough to serve as a model, as with 
 this metal there is practically no shrinkage and it will make no 
 difference whether the face of the die presents the cameo or intaglio 
 
EXTEXSfOX SADDLE BR I DUES Wll 
 
 .(Fig. ()01). These models should W at least one iiieli in drpth so 
 that there will be no saii;<;in^' or sprinoini.- of the die in swaj^niig-. 
 
 Where fusible metal is used, the sides of the model slioiild be 
 made nearly parallel so tliat the dies will be of that shape. The 
 
 Fig. 602 
 
 mould may be made of .saud, or preferably of Dr. (Jritman'.s calear,' 
 and the fusible metal poured in this. It will only be neeessarv 
 to get one die for eaeh side from a ealear mould, as all the other 
 dies and counter dies which are needed can be .secured from the 
 original casting. 
 
 'i'he metal should be poured in the mould when it is not in a 
 very liquid state, but it should be hot enough to allow it to pour 
 fairly freely. This die i> then chilled and wrapped in paper and a 
 gum band [>laced around it, as in Fij,'. (■)()2. The sides of the die 
 being parallel makes it of a good shape for pourinj; the counter 
 die. The die is then dusted with talcum powder and the coimter 
 
 ' Marl>l<' (iiiHt, rn(jiMl«'ii<'l with glycerin riii<l w.itcr, ii clcjirily, :uiii t;ik<s Hit 
 |j|;w<' fif tii'ililinK .h;iii(|. 
 
328 PORCELAIN CROWNS AND REMOVABLE BRIDGE-WORK 
 
 die poured. In pouring the counter die, the metal should be as 
 cold as it is possible to pour it. It is poured into the paper on the 
 die until it is about the same depth as the die itself. 
 
 After it has become chilled, it is readily separated and another 
 counter poured from each of these. By wrapping in paper and 
 dusting with talcum powder, in the same manner as in the first 
 operation, any number of dies and counter dies can be secured 
 and everyone will be an exact duplicate of those just made. 
 
 If the die is chilled and the counter die poured as cold as it can 
 be made to flow, they will not stick," but will readily separate. As 
 a rule, two dies and counter dies will be sufficient for swaging the 
 plate, especially the buccal which is thinner than the lingual plate 
 but for the lingual side it is sometimes well to use three as a sharper 
 outline will be obtained in the plate than if only two had been used. 
 
 The dies and counter dies made, the buccal plate is struck up 
 from No. 30-gauge coin gold, festooned carefully to fit around the 
 facings accurately and carried over the heel of the saddle to about 
 two-thirds the width of the cusp from the buccal side. The lin- 
 gual plate is struck from No. 28-gauge coin gold and carefully 
 fitted, the part going over the heel being brought in contact with 
 that from the buccal side. The plates should be cleansed in nitric 
 acid after each swaging and before they are trimmed or annealed, 
 otherwise one heating after swaging, would entirely destroy them. 
 
 Fig. 60.3 
 
 After the final swaging, and when the plates have been thoroughly 
 cleansed in acid, the pink wax js removed from .around the facings 
 and the saddle on the buccal side. The buccal plate is placed in 
 position and held with small iron clamps, as in Fig. 603, two or 
 three clamps being sufficient for the purpose. The saddle is then 
 held over a small alcohol flame for a moment, or a hot instrument 
 is held beneath it, to loosen the wax from the plate, and the teeth, 
 with the body of the wax, are removed and laid carefully aside 
 (Figs. 604 and 605). 
 
EXTENSIOX SADDLE BR I DUES 329 
 
 Investing the Saddle. — The inner caps are removed ami the saddle 
 is invested, lingual side down, only enougli of the investment 
 being used to keep it from springing (Fig. 60G). The inside of the 
 caps are filled with investment, care being used not to allow the 
 investment material to come o\er the part which is to be soldered. 
 
 Fig. 604 Fic 605 Fi<;. 60() 
 
 The investment should then be thoroughly dried out, the piece 
 well fluxed between the plate and the saddle and some pieces of 
 18-carat solder dropped in where the saddle and the plate are to 
 be united (Fig. 600, a). The investment is then well heated up and 
 when it has reached a red heat, the blow-pipe flame is thrown 
 on the underside of the saddle next to the investment and the 
 solder drawn through from the inside all around. 
 
 As the solder begins melting at one point, tiic flame of the blow- 
 pipe is moved along slowly from end to end until the solder shows 
 all along the outer edge, giving a perfect union between the [)late 
 and the saddle. Twenty-carat coin solder may be used for this 
 purpose, but as the coin solder has a much higher fusing point than 
 the 18-carat, a great deal more care is rc(|uircd in using, otherwise 
 the buccal plate may be burned. In using the 2()-carat solder, it 
 is fed along and drawn in from the outer edge, using the solder 
 in a strip. However, as the solder will not show at this place, 
 it is safest to use the 18-carat. 
 
 After the investment has been allowed to cool the saddle is 
 removed, cleansed in acid and dried. The saddle is then warmed 
 slightlv and the body of the bridge (Fig. (j()4) is pressed back into 
 place until the fitting of the lingual plate shows that it is in its 
 correct [)osition. The bridge is now ready for the filial soldering. 
 
 Soldering the Body of the Bridge and the Lingual Plate. In all sol- 
 dering operations, cleanline.ss is ab.solutely essential, and there is 
 no greater enemy to the free flowing of solder than is plaster-of- 
 I'aris. (Cleanliness is especially needful in soldering a bridge of this 
 character, as such a high degree of heat is required to make the 
 solder flow in places whirh are deep down in the body of the bridge, 
 
330 PORCELAIN CROWNS AND REMOVABLE BRIDGE-WORK 
 
 that, unless perfect cleanliness is obtained, there is a great liability 
 of burning the exposed parts. All of the parts which are to be 
 soldered should be covered with wax before investing. The invest- 
 ment having been mixed it is placed on the slab to the depth of 
 about one-half of an inch. The bridge is laid buccal side down on 
 this and worked into it for perhaps one-eighth of an inch by using a 
 slight pressure on the lingual side, agitating it slightly, and keeping 
 the edges of the cusp and the lower edge of the saddle on a level. 
 
 With a small instrument (the curved end of the small wax spatula 
 is suitable) the investment is worked up so as to cover a little more 
 than one-half of the cusps and over the labial side of the saddle so 
 as to cover about one-half of it, leaving the lingual half of the 
 saddle and the lingual third of the cusps exposed, as shown in 
 Fig. 607, a a. 
 
 Fig. 607 
 
 Fig. 608 
 
 Fig. 609 
 
 Before the investment has thoroughly hardened, it is trimmed 
 to the proper size and should be kept as small as possible, and still 
 give support to the bridge. All of the trimming should be done 
 at this time, before removing any of the wax. All the parts which 
 are to be covered with solder should be cleansed, the plaster scraped 
 off, and the nearby parts rubbed off with a damp cloth,. or washed 
 so that no plaster will remain. After the investment has hardened, 
 it is warmed a little, to slightly soften the wax in contact with the 
 different parts, and the bulk of the wax is lifted out, and the remain- 
 der can be washed out with boiling water. 
 
 It should then be dried out thoroughly with a gentle heat and a 
 little powdered calcined borax sprinkled inside the body of the 
 bridge. The piece is then heated up slowly until it is of a bright 
 red heat and it is ready to solder. 
 
 Twenty-carat solder is first used at the mesial end to unite the 
 saddle and cusps firmly to the abutments and then at the distal end, 
 should there be an anchorage at that end, or should the cusp be 
 attached to the end of the saddle. The solder is then flowed over 
 the backings of the teeth and over the saddle and up to, and 
 
EXTENSION SADDLE BIN DOES 331 
 
 between the cusps so that all the exposed parts will show nothing 
 but 20-carat solder. The backings of the facings should be covered 
 to the depth of perhaps a thirty-second of an inch or sufficient to 
 cover the pins of the facings and coming up on the saddle and the 
 under side of the cusps, as shown in the drawing (P'ig. GOS). It is 
 not necessary, nor is it desirable, that this space be entirely filled, 
 as that would make the bridge entirely too heavy, but only enough 
 solder is used to give the necessary strength to the piece. After 
 this has been finished, the soldering of the lingual plate may be 
 undertaken. The under surface of the plate at the upper and lower 
 edges is well fluxed, using the liquid flux and applying a little at 
 a time and passing it through the flame to dry it off. The lower 
 edge of the saddle and also the lingual sides of the cusps at point 
 a and a, in Fig. 608, are then fluxed and a little IS-carat solder is 
 flowed over these points throughout the length of the bridge. Sol- 
 fler is best used in a strip in applying it to these points. 
 
 The piece is then well heated up and the lingual plate placed care- 
 full\- in i)()sition (Fig. (iOQ). The whole bridge is brought to a bright 
 red heat, a brush Hame being used until the solder begins to melt, 
 when a i)()inted flame should be used, passing it along the upper 
 side, throwing the Hame on the cusps (Fig. ()()9, a), and moving from 
 one end of the bridge to the other until the solder has drawn through 
 at every point and the jjlate united firmly to the cusps. If there 
 are anv points where the plate has not quite dropped into position, 
 a pair of pliers may be used, one beak grasping the plate where it 
 is not in exact contact, the other beak being on the underside of 
 the investment, as in Fig. (ilO, a, and as the solder flows, the i)late 
 can be pressed in contact with the cusps, as it will bend very easily 
 under heat. 
 
 The occlusal side of the j)late being proi)erly attached, the oj)era- 
 tor's attention is next turned to the lower side. The ])iece is 
 reversed so as to bring the lower edge of the saddle toward the 
 operator, and the Hame is thrown on the under part of the saddle 
 (Fig. 009, b), which is heated until the solder draws freely from the 
 inside and has flowed along the whole length of the saddle. If it 
 stands away at any point, it should be brougjjt together with tiie 
 pliers while the solder is molten, until it is in perfect contact all 
 around fFig. 010, h). Over the heel of the saddle, where the buccal 
 and lingual plates come in contact, a little solder should be flowed 
 until the two plates are perfectly united. 
 
 Twenty-carat solder inay be used f(»r soldering on (lie lingnal plate 
 
332 PORCELAIN CROWNS AND REMOVABLE BRIDGE-WORK 
 
 by first fluxing the cusps and the lower edge of the saddle and 
 then placing the lingual plate in position. The solder is used in 
 a strip and a small amount placed at a point of contact of the plate 
 with the cusps, tacking it a little at first, and then feeding the solder 
 
 Fig. 610 
 
 in and moving it along slowly from one end of the bridge to the 
 other. The lower side of the plate is now attached to the saddle 
 in the same manner, feeding in the solder in a strip, and gradually 
 drawing it through from one end to the other, after which the ends 
 of the buccal and lingual plates, which come together over the heel 
 of the saddle, are soldered. 
 
 The 20-carat solder is of a so much higher fusing point than the 
 eighteen that it is safer to use the 18-carat unless the operator 
 is an expert in the use of the blow-pipe. If, however, the plate 
 has been carefully fitted, the line of solder at the point of union 
 of the cusp with the plate is so fine that the difference in the color 
 will not be noticeable. The greatest care must be used in solder- 
 ing on this plate and the pointed flame should not touch it as the 
 piece is necessarily brought to such a very high heat that the 
 lingual plate can be burned in an instant, thus destroying it, and 
 necessitating making a new one. 
 
 After the bridge has cooled it is removed from the investment, 
 boiled in dilute sulphuric acid and washed in a solution of bicar- 
 bonate of soda and then rinsed in clear water. It is next dried as 
 well as possible and then dipped in alcohol, or alcohol poured over 
 it, and then again dried thoroughly, so that before any finishing 
 is undertaken, there will be no moisture in any part, as should 
 there be any moisture present, the dust of the grinding will work 
 in the crevices and the spaces between the plate and facings, leav- 
 
EXTEXSIOX SADDLE BRIDGES ooo 
 
 inu" (lark lines which will present a very disagreeable appearance 
 This applies to the finishing of all bridges or crowns. 
 
 The bridge is then finished, first nsing fine carbornndnm wheels 
 and grinding away any edges of the cusps, which may overhang 
 the facings, luitil tlie>- are perfectly flush with the facing. 
 
 In grinding the cusps the grinding should always be done from 
 the gold to the porcelain, thus burnishing the gold over the facing 
 and making perfect joints. By so doing there will be no danger of 
 fracturing the thin edge of the facing. On the contrary, if the grind- 
 ing is from the porcelain to the gold, the fine edge of porcelain at 
 that point will be shivered, making it rough, and impairing the 
 beauty of the work. 
 
 On the other side, the lingual plate is ground flush with the 
 cusps and the lower edge of the saddle on both Ijuccal and lingual 
 sides are smoothed and rounded. It should not be necessary to 
 touch either the lingual or buccal plates with the stone, if care has 
 been used in obtaining smooth dies, and the plates have not been 
 marred in swaging. The heel of the plate is finished with carborun- 
 dum stones and afterward all of the parts which have been ground 
 are smoothed oft* with sandpaper, or emery disks, and then cuttle- 
 fish, so that there will be very little finishing to do on the lathe. 
 
 The piece is now i)laced on the model and articulated and the 
 cusj)s are carved as desired. 
 
 Filling Beneath the Buccal Plate with Cement. — The next step, 
 before the final polishing of the piece, is to fill the buccal side with 
 cement. One of the points of the buccal plate, which has extended 
 up between the facings, the point most nearly central should be 
 used, is thrown out from between the teeth a little, suflficient to 
 allow of the insertion of the point of a cement syringe (Fig. (ill), 
 and oxyphosphate of zinc, mixed fairly soft, should be forced 
 in between the plate and the saddle and facings, tilling the space. 
 The cement should be forced in until it can be seen working its 
 way out at both the mesial and distal ends around the necks, 
 between the facings and the plate. While th*- cement is still soft 
 the point which has been thrown out to allow for the entering of 
 the syringe point, is pushed back into ])lace between the facings. 
 
 After the cement has hardened, the excess should be cleaned away 
 from around and between the teeth. The spaces l)etween the teeth 
 are now p;irti:dl,\ filled in with gold, a plastic gold will be found 
 bf^t for tlii^ purpose, and carried «)\(T tin- jxtiiits (tf (he plate w liidi 
 extend up between the faring-. The ,-.paee> should be filled so as 
 
334 PORCELAIN CROWNS AND REMOVABLE BRIDGE-WORK 
 
 to enable them to be smoothed nicely and also to obliterate any 
 crevices or spaces which might serve as a lodgment for foodstuffs. 
 The fillings are then smoothed and the bridge is finally polished. 
 
 Fig. 611 
 
 Polishing the Bridge. — A felt wheel with pumice may be used 
 over the surfaces, which it has been necessary to grind, but over 
 the buccal and lingual plates a fine brush wheel, with a little fine 
 pumice, may be used for just a moment. Small leather wheels 
 mounted and used in the engine can be used in the small places. 
 After the bridge has been washed, the rouge is applied. This can 
 be used over the larger part of the bridge on a felt wheel, but over 
 the fluted and uneven surfaces of the plates and the fillings between 
 the teeth, the rouge should be used on a fine brush wheel, and the 
 whole polished until the surface is smooth and highly finished. 
 
 SADDLE BRIDGES. ABUTMENTS AT BOTH ENDS. 
 
 Where there is an abutment at each end of the saddle, the bridge 
 is made in practically the same manner as the extension bridges. 
 
 In the anterior part of the mouth, the saddles are struck up and 
 the relation, as in the case already described, of the saddle with the 
 abutments, is secured with the saddle under pressure. Where it 
 
SADDLE BRIDGES—ABUTMEXTS AT BOTH ENDS '^',^h 
 
 is possible to do so, the facings are ground Hush with tlie gum, the 
 saddle coming only to the lingual side (Fig. 6 12), but where there 
 is great depth from the gum to the incisal edge of the teeth and 
 where the lip is long and it is not possible to see the gum, or 
 where greater fulness is desired, the saddle may be extended over 
 
 Fk;. G12 Fig. 613 
 
 the ridge and made in practically the same way as the extension 
 saddle already described, a labial plate being swaged and fitted 
 around the teeth and connected to the saddle as are the buccal 
 plates to the saddle previously described (Fig. 611^). 
 
 The facings are then backed and soldered in the usual manner, 
 and the lingual sides carved and finished as desired. 
 
 There are cases where there has been great recession and shrink- 
 age of the process and tissues, when it may be necessary to use 
 single gum teeth, and in these cases the teeth are ground in the 
 usual manner, the saddle coming in contact with the lingual sides 
 of the teeth. 
 
 In other cases, detachable facings ma\' be indicated, the gum 
 contour can be restored by building out with porcelain gum body, 
 and the whole cemented after the bridge has been soldered and 
 completed, but no rule can be laid down covering the adaption of 
 these different styles of work, each must be decided by the indi- 
 vidual requirements of the case. 
 
CHAPTER XV. 
 RETAINING MEDIA. 
 
 The zinc oxyphospliate employed in the setting of crowns or 
 bridges should possess the characteristics which would recommend 
 the specimens to be used as filling material, and should be what 
 is known as a hydraulic cement. It should, however, flow freely, 
 and, as the difficulty of maintaining dryness is increased, it should 
 set promptly and yet with sufficient deliberation to permit of the 
 accurate adaptation of the crowns. 
 
 The operator should be familiar Avith the peculiarities of the par- 
 ticular cement he is using, as specimens of the different makes of 
 oxyphosphate differ so markedly in their behavior, that it is unsafe 
 to use them for this purpose without having first tested them. 
 
 The value of a cement depends as much, perhaps, upon the 
 manner in which it is mixed as upon the kind of cement which 
 is used. The cement should always be thoroughly spatulated. 
 A little of the powder should be first well worked into the liquid, 
 a very little of it being dissolved during the process. The powder 
 is then added a little at a time, mixing it well until enough has 
 been incorporated to give it the desired consistency and the whole 
 mass is perfectly smooth and creamy. 
 
 The spatulas used should be strong and of ample size to do the 
 work thoroughly. Fig. 614 shows a spatula suitable for single 
 crowns or small bridges, but for large bridges, with several abut- 
 ments, where a large mix is required, a spatula such as shown in 
 Fig. 615 or one even larger, is indicated. In this case a large slab 
 should be used. A piece of plate glass about four and a half inches 
 by six inches will answer nicely and is none too large. 
 
 Setting Crowns with Oxyphosphate of Zinc. — It is advisable to set 
 all pin crowns so that they can be taken off without mutilation, if 
 at some future time it should be desirable to do so for the purpose 
 of repairing them, or in case they should be needed as anchorages 
 for a bridge. An excellent method of setting them so that they 
 will be perfectly rigid and at the same time be easily detachable, is 
 first to give the pin and the inside of the cap and band a thin coat- 
 
CEMENTING BRIDGES IN THE MOUTH 
 
 337 
 
 ing of chloropercha. A convenient way to do this if a solution is 
 not at hand, is to take a fine camel-hair pencil, dip it in chloro- 
 form and then rub it on base-plate jjutta-percha and paint the cap 
 and pin with this extemporized chloropercha. The solution will 
 dry ^-ery quickly and the crown is then set in the regular way, with 
 ox\phosphate of zinc. If at any time it is desired to remove the 
 crown, it can be easily done with a pair of heated forceps or pliers. 
 
 I'lc;. CI 1 
 
 Via. 615 
 
 CEMENTING BRIDGES IN THE MOUTH. 
 
 In nearly every case, whether a bridge l)e fixed or removable, it is 
 better that it be worn in the mouth without cementing for at least 
 from twenty-four to forty-eight hours. This will allow it to adjust 
 itself and settle in ])hu'e and render the cementing of the piece easier. 
 
 Cementing Fixed Bridges. — After the bridge has been worn for a 
 time and removed from the mouth, it is first thoroughly cleansed. 
 After washing well with soap and water and a brush, it is dried and 
 the inside of the abutment caps washed with nitric acid, after whicii 
 it is again washed with water and dried with alcohol. 
 
 The abutments in the mouth are then cleansed and it is a good 
 plan, especially if the piece has been worn for some time without 
 cementing, to clean them first with pumice, using a small brush 
 on the engine, afterward rinsing the mouth well. In keeping the 
 mouth dry, napkins are preferre<l to cotton rolls as the latter are 
 .so fibrous that some of the fibers may make their way over the 
 abutments and when the caps are cemented, a f<'w fibers might 
 allow for the entrance of moisture and so escntually cause trouble. 
 22 
 
338 RETAINING MEDIA 
 
 The napkins are placed so as to keep the field of operations as 
 dry as possible. The teeth and canals are first wiped with a solu- 
 tion of bichloride of mercury and peroxide of hydrogen and dried 
 off. If there is any tendency to bleeding, the gums may be wiped 
 with adrenalin chloride. They are then washed with alcohol and 
 thoroughly dried again with hot air or a root drier. 
 
 Fig. 616 shows the Evans root drier. It consists of a copper bulb 
 through which is passed a silver or copper point. A handle is 
 screwed into this holding the point firmly in place. The copper 
 bulb is heated in the flame and the heat is transmitted to the end 
 
 Fig. 616 
 
 of the point which is placed in the canal, drying the root out quickly. 
 A fine point is used when the entire canal is to be filled, but a 
 heavy one can be used to dry out the canal where a crown is to be 
 placed on the root. 
 
 The cement is now mixed and if the canals are to receive a post 
 these are first filled, a cement syringe is here indicated, and then 
 the caps on the bridge are filled full of cement and the bridge is 
 pressed firmly in position in the mouth. The napkin is then removed 
 and the patient is instructed to close the teeth, and the mouth is 
 carefully examined to ascertain that the bridge is in its proper 
 position. If everything is all right, the patient is told to keep the 
 teeth closed without the slightest movement of the jaws and this 
 position should be kept for at least ten minutes. Sometimes it 
 will make it easier for the patient if the operator or his assistant 
 holds his hand under the chin, pressing it upward during the setting 
 of the cement. At the end of from twenty minutes to one-half 
 hour, the excess cement can be removed from around the edges of 
 the caps, the gums wiped off with some soothing preparation and 
 the patient dismissed. ^ Another appointment should be made for 
 twenty-four or forty-eight hours later when the mouth should again 
 be carefully examined to see that everything is as it should be. 
 
 ' Campho-phenique is excfllent for tliis purpose. 
 
CEMENTING BRIDGES IN THE MOUTH 339 
 
 The patient may again lie seen a couple of times at intervals of a 
 week or two before being finallx ilismissed. 
 
 Cementing Removable Bridges. — In cementing removable bridges, 
 the work is done in practically the same manner as in the case of 
 a fixed bridge. The piece is worn for a time and when removed 
 is thoroughly cleansed, the inner caps being removed and cleansed 
 in nitric acid. After cleansing, the inner caps are put back in place 
 in the bridge and film of pink paraffin and wax run around the 
 edge of the outer caps where they overlap the inner caps. It 
 should be run on quite hot so that it will stick well, and on the 
 anterior, where porcelain crowns or facings have been used, the 
 line between the half-band and inner caps should be well covered 
 and also on the labial side between the outer and inner floors. 
 Great care must be used not to get any of the wax on the inside 
 of the inner caps. If this happens, it must be carefully removed 
 before cementing. The object of waxing the bridge so carefully 
 in this manner is to prevent the possibility of any cement working 
 in between the outer and inner caps and so making a fixed bridge 
 out of a removable one. 
 
 The bridge being thus prepared, the remainder of the work of 
 cementing is done in exactly the same manner as for a fixed bridge. 
 After cementing, the teeth are kept firmly closed for fifteen or 
 twenty minutes and then the bulk of the excess is removed, but it is 
 not removed from around the gum margin at the edge of the caps 
 at this time. The patient is dismissed and another appointment 
 made for the following day or several hours later the same day when 
 the bridge is removed, the inner caps remaining firmly cemented 
 to the abutments. The wax and excess cement is now carefully 
 remo\'ed from around the caps and from beneath the gum and the 
 gum wiped with camj)ho-phenique. 
 
 The patient is instructed in removing and replacing the bridge 
 and dismissed with instructions to remove the work at stated 
 times for cleansing. The patient should be seen frequently for the 
 first few weeks to see that everything is all right. They should 
 always report at intervals of from four to six months for examina- 
 tion and by so doing, the work can be watched and kept in jx'rfect 
 condition for many years. 
 
 Cementing Inlays for Removable Bridges. \\ licre inlay abutments 
 are used as attaclinicnts for r(in()\ablc bridges, the inlays are 
 cemented .sej)arately. This is the only in.stance in removable work 
 where the parts are not assembled arifl the whole treated as a fixetl 
 
340 . RETAINING MEDIA 
 
 bridge. The bridge is worn for a time without cementing and then 
 the inlay is removed and thoroughly cleansed and cemented in 
 place, being held under pressure until the cement has hardened. 
 The excess cement is then trimmed away and the inlay is finished 
 and polished. The balance of the bridge is then treated the same as 
 a fixed bridge. Wax flowed between the outer and inner caps and 
 everything cemented in place. 
 
 The reason the inlay of a bridge of this kind is set separately is 
 that there is only one way for it to go, and that is the right way. 
 If it should- happen to be twisted the least bit one way or another, 
 it would clear the margins of the cavity at certain points, thus 
 leaving a line of cement exposed, but if it is set separately, this 
 can never happen. 
 
 Fig. 617. — About two-thirds actual size. 
 
 The cement syringe shown in (Fig. 617), is & most useful aid in 
 cementing crowns or bridges, especially where several pin crowns, 
 either single or as abutment pieces, are to be set at one time. The 
 syringe consists of a nickle-plated brass cylinder or barrel with 
 a needle or tube small enough to enter the enlarged canal, and a 
 nickle-plated brass plunger. There is an opening in the side of the 
 cylinder for the introduction of the cement. The root is thoroughly 
 dried and the cement mixed to the consistence of thick cream and 
 placed in the cylinder. The piston is then put in the barrel and the 
 end of the needle carried to the end of the canal and the cement 
 forced into it, at the same time withdrawing the needle slowly. 
 In this way, the apical extremity of the canal is filled first. A 
 number of roots may be filled in this manner in a few seconds and 
 there will be ample time to put the crowns or bridge in place before 
 the cement has set. 
 
 As soon as the piece is in place, the syringe is plunged into a basin 
 of cold water and the piston worked back and forth to free it from 
 the remaining cement while this is still soft. It is also well to rinse 
 afterward with a solution of bicarbonate of soda so that any remain- 
 ing particles of cement may be easily removed. If the cement is 
 too hard to be forced out, it may be removed with the drill which 
 comes with the syringe for this purpose. 
 
SETTIXa CROWNS WITH GUTTA-PERCHA .341 
 
 SETTING CROWNS WITH GUTTA-PERCHA. 
 
 When gutta-percha is to be employed, it is necessan- that the 
 several parts shall be at a temperature which will permit" the ready, 
 deliberate, and accurate adjustment of the crown and gutta-percha 
 to the root. 
 
 The crown is laid ui)()n a gutta-percha heater. Dr. How's steatite 
 slab IS useful for the purpose (Fig. 618), or in the absence of this 
 appliance, it may be heated over a small alcohol flame. A piece of 
 base-plate gutta-percha is also laid on the slab, or heated over 
 the flame of the lamp, and when soft is pressed out between the 
 fingers into a sheet, which is wrapped around the heated post. 
 
 Fig. 618 
 
 The canal is moistenefl so that the crown may easily be removed 
 and the crown forced on to the root as far as possible. It is 
 then removed and the surplus gutta-i)ercha, which has been 
 squeezed out around the edge of the band, is removed, after which 
 the canal is again moistened and the crown heated and pressed 
 into place. This is rcfjeated until the crown goes up to its normal 
 position. It is then removed and cleansed and dried with alcohol 
 and a very slight excess of gutta-percha is placed around the pin. 
 A napkin is now placed in position to keep the field of operation 
 dry and the canal is dried thoroughly and then wiped out very 
 lightly with one of the essential oils, preferably eucalyptus. The 
 crown is now again licated and forced up into place. Any excess 
 of gutta-percha wliicli may have been squee/>ed out over the margins 
 of the crown is removed, and the work is completed. 
 
 If the above instructions have been carefully carried out, a crown 
 set in the manner described will be as permanent, and gi\-e prac- 
 tically as goori results as though set with oxyphosphate of zinc and 
 at the sanu; tinu; possesses tlu' advantage of easy removal, should 
 this be desin-d. 
 
CHAPTER XVI. 
 
 REPAIRING CROWNS AND REPLACING BROKEN 
 
 FACINGS. 
 
 Removing Shell Crowns. — When, for any reason, it may he found 
 necessary to remove a full gold crown from a tooth, if the crown 
 has been properly fitted and cemented, it will generally be neces- 
 sary to cut the band in order to get it off. This may be easily done 
 with one of the crown slitters which are made for the purpose, as 
 illustrated in Fig. 619. With one beak resting on the cusp and 
 the other caught under the gingival edge of the crown, the forceps 
 are closed, dividing the band all of the way to the cusp, when 
 by giving a slight rocking movement, the crown may generally 
 be easilv lifted off. Should this not be the case, an instrument is 
 passed under the flap and worked around the tooth to loosen the 
 cement and the band gradually worked free (Fig. 621). A hatchet- 
 shaped excavator can often be used to do the cutting, the blade 
 being repeatedly drawn from the cervical edge to the cusp, until 
 the band is divided. A small wheel bur will do tbe work, cutting 
 from the cervix to the cusp in the same way as with the excavator. 
 
 One of the best instruments for use as a crown slitter is one 
 which was not designed for the purpose. This instrument is the 
 old Physick forceps, used in the extraction of lower third molars 
 (Fig. 620). The edges at the end of these beaks should first be 
 sharpened and it is then ready for use. It is almost universal in 
 its application and either beak is used for cutting. One of the 
 beaks is placed on the occlusal surface of the crown and the other 
 over the gingival edge and the band is split by closing the forceps. 
 
 Repairing of the Shell Crown. — In repairing the shell crowns, the 
 cement is first thoroughly removed and if it should happen to be 
 one made by the operator and a sweated crown throughout, the 
 edges can be brought together, a small strip of coin gold placed 
 over it and melted in place. In making a repair of this character, 
 the crown should be placed on a piece of charcoal with the cusp 
 toward the operator. The flame of the blow-pipe is then thrown 
 on the cusp until the whole crown is entirely heated-up nearly to 
 
REPAIRIXC OF THE SHELL CROWN 
 
 mm 
 
 mm 
 
 
 
 I'm:. (il!» 
 
 Via. 020 
 
344 REPAIRING CROWNS AND REPLACING BROKEN FACINGS 
 
 the melting point, when the flame is flashed across the break and 
 the coin gold melted over it (Fig. 622). 
 
 If it is a soldered crown and there is no loss of material, the 
 edges are simply brought in contact and solder flown over it. If 
 
 
 Fig. 622 
 
 there has been much loss of material at the sides of the cut, a 
 narrow strip of thin platinum or of pure gold is waxed over the 
 
 Fig. 623 
 
 Fig. 624 
 
 line of division on the inner side of the cap which is then filled 
 with investment material, dried out and the broken part covered 
 with solder (Fig. 623). 
 
REMOVAL OF POST 345 
 
 Removing of Porcelain or Porcelain-faced Crowns. — The remoxal and 
 repairing of a porcelain-faced crown is a more difficult operation than 
 of a shell crown. If the crown has been set with gutta-percha, it 
 may be easily removed by grasping it with a heated pair of pliers, 
 or forceps, having first protected the lips and gums of the patient 
 with napkins. It is well to try this method first on a chance of 
 gutta-percha having been used. If it has been set with oxyphos- 
 phate of zinc, much more trouble will be experienced in getting 
 it off. It will be necessary first to separate the cap from the 
 pin, which may be done by passing a drill from the labial side 
 through the base of the backing at its junction with the floor of 
 the cap to one side of the pin and then cutting the pin through with 
 a very small fissure bur, after which the cap is easilv pried off (Fig. 
 624). 
 
 Removal of Post. — 'J'here is on the market an instrument designed 
 for removing a post from the root consisting of a pair of jaws 
 which grasp the post, while another pair rests against the end of 
 the root. When the pin is tightly clamped, a screw at the end 
 of the instrument is turned, and if the post is not ver\' long or 
 has not been well cemented it can be removed without difficulty- 
 (Fig. 625). Where, however, the pin is long and has been well 
 
 Fk;. 62.^. l>iii Ic uiiuit post-puller. 
 
 cemented, it will be necessary first to cut away the cement from 
 around it until it has become somewhat loosened, then the instru- 
 ment may be used to remove it. 
 
 In the absence of one of these instruments, the work can generally 
 be done within a short time by other means. The cement is first 
 l(M)sened from around the pin with a very fine s|)ear-i)<)inted drill. 
 Th«' shank of one of the finest burs or of a (Jates-CJliddcn drill, 
 flattened on two sides and then ground to a sjiear point makes 
 an excellent drill for the purpose, being smaller than an.\ obtain- 
 able at the dental d<'{)ots. The cem(Tit is drilled away close to 
 the [)in all around, inclining the drill toward the post at all tim«'s 
 
346 REPAIRING CROWNS AND REPLACING BROKEN FACINGS 
 
 so as to lessen the danger of a perforation or a possible weakening 
 of the root by cutting into it (Fig. 620, a and h). 
 
 From time to time an effort may be made to loosen the pin by 
 grasping it with a pair of strong, narrow-nosed pliers and trying 
 
 Fig. 626 Fig. 627 
 
 to rotate it. The pin roughing and bending pliers may be used 
 for the purpose. Very often the nose of the pliers is somewhat 
 blunt, but it may easily be reduced by grinding (Fig. 627). 
 
 If the pin does not loosen, the drilling should be carried deeper 
 until it can be removed. The remainder of the cement is then 
 removed from the canal with a reamer and a new pin fitted to it. 
 The palatal portion of the crown with the backing should then 
 be cut away the cap placed on the root and a new pin waxed in 
 place. The cap and pin are now removed, invested and soldered, 
 after which the facing is ground, backed and the crown soldered. 
 
 REPLACING BROKEN FACINGS ON FIXED CROWNS OR 
 
 BRIDGES WITHOUT REMOVING THE APPLIANCE 
 
 FROM THE MOUTH. 
 
 There are several different methods of replacing a facing without 
 removing the cap and pin from the root. A good way, and one 
 which makes one of the strongest repairs that can be made, where 
 the remaining metal portion of the crown is of sufficient thickness, 
 is as follows: The remnants of the tooth pins are first removed 
 and ground flush with the backing, and an impression taken cover- 
 ing the backing and floor of the cap, and a model made of plaster, 
 cement or Spence metal. A hole is then cut in that face of the 
 model representing the backing, against which the new facing is 
 to be fitted, large enough for the pins to enter freely (Fig. 628). 
 The facing is then selected and ground to fit the model accurately. 
 The backing of the crown in the mouth is then cut out to accom- 
 modate the pins, care being used not to break through on the 
 
REPLACIXa BROKE X FACINGS 
 
 :U/ 
 
 lingual side. The cavity is tiien deeply undercut all around, making 
 it strongly retentive in shape ( Fig. 029, a, b and r). Fig. (ioO, a, being 
 
 / 
 
 Fig. 628 
 
 Fig. 629 
 
 Fig. 630 
 
 Fig. 631 
 
 a horizontal cross-section of the backs. The pins of the facing are 
 flattened at the ends and bent at right angles, one being cut a 
 little shorter than the other so that when the long pin is inserted 
 and the facing pressed as far to that side as it will go, the short 
 pin will pass through the opening in the backing (Fig. 630, b). 
 The facing is now removed and the cavity filled with cement, and 
 the backing and floor covered. The long pin is first introduced, 
 the facing carried to that side until the shorter one 
 will enter. It is then pressed tightly in place and then 
 forced back until the sides of the facing are even with 
 the backing. This will bring the ends of both the 
 short and long pins under the ledge of the cavity 
 and when the cement has hardened, the facing will be so firmly 
 held that it would be impossible to remove it except by breaking 
 it (Fig. 631). 
 
 Another method of repair without removal from tlie mouth is 
 that of riveting the facing to the backing. This is one of the oldest 
 methods, and also one of the best if it is carefully done. The pins 
 are cut from the backing, an impression taken and a model prepared 
 as in Fig. 628. The new facing is ground to fit the model. A 
 backing of heavy tinfoil or paper is fitted to it and trinmied care- 
 fully to the edge of the facing all around. This backing is then 
 remcA'ed and fastened in position over the gold backing of the 
 crown in the mouth (Fig. 6:»2). The holes in the backing will show 
 the exact position of the pins of the facing, and the holes may be 
 drilled with a small spear-pointed drill the exact size of the pins. 
 The holes are then countersunk from the palatal side and the 
 pins cut oft" so that they will i)roject only a slight (lisianre through 
 the backing CFig. 6.')3). 
 
348 REPAIRING CROWNS AND REPLACING BROKEN FACINGS 
 
 The riveting is done with a plate punch. The facing is removed 
 and the backing and floor of the cap covered with cement of about 
 the same consistence as that used in setting a crown and the facing 
 
 Fig. 632 Fig. 633 Fig. 634 Fig. 635 
 
 placed in position. A piece of lead or a thickly folded napkin is 
 placed over the facing, with the die side of the punch resting on 
 this, and while the cement is yet soft, the pin is riveted by rubbing 
 and burnishing with the punch end of the forceps until the counter- 
 sink is entirely filled (Fig. 634) . After riveting, any excess platinum 
 of the pin may be ground away and the back polished. If the pins 
 are carefully riveted, and the holes are not too large, this makes as 
 strong a repair as can be made by any method. If the cement 
 has been allowed to harden before the riveting is done it will be 
 broken and will crumble away, and the repair will not be as satis- 
 factory. 
 
 Another method of repair is as follows: The headed pins are 
 left in the backing (Fig. 635) and the pins of the facing, which is 
 to replace the one broken, are ground out and the holes dove- 
 tailed. This may be done by very simple and easily made iastru- 
 ments. The first requisite is a trephine for grinding out the pins. 
 This can be made by using the shank of a bur, and filing it down 
 at the end until the point is slightly larger than the tooth pin 
 (see Fig. 636). On this is fitted a tube about one-half inch long, 
 made of ordinary brush copper. No. 36 gauge. The copper is cut 
 about one-half an inch wide, and rolled around a pin or mandrel 
 about the size of the tooth-pin. It is rolled around twice so as to 
 form a tube with sides doubled the thickness of the metal (Fig. 
 637, a). The end of the bur shank is then inserted into one end 
 of this tube, and the whole fluxed with zinc chloride and soldered 
 with ordinary tinner's solder (see Fig. 637, h). 
 
 Carborundum and glycerin should be used for grinding. The 
 instrument is placed in the engine and the tube dipped in the 
 carborundum and glycerin, and then placed over the pin and the 
 
REPLACING BROKEN FACINGS 
 
 :U9 
 
 engine started (Fig. 638). The instrument is raised and lowored, on 
 the facing, as it revolves, allowing the abrasive powder and liquid 
 to constantly work under it. This is kept up until the pin is entirely 
 ground out. After the pins are ground out, the hole is dovetailed, 
 
 Fig. G3() 
 
 Fi.i. (J.17 
 
 Fig. 638 
 
 Fig. 039 
 
 which ma\' be done 1)\' using an old wheel or in\Trted cone bur 
 from which the temper has been drawn. This is dipped in the 
 carborundum and glycerin and then ])laced in the hole and the 
 engine run rapidly until the hole is well undercut all around (Fig. 
 639). The powder is then well washed out and the holes filled with 
 cement. The backing of the tooth, which has previously been well 
 dried, is covered with cement and the facing pressed into place and 
 held there until the cement has hardened (Fig. 040). 
 
 Fig. 64fl 
 
 'J'liis makes a quick and easy repair, but where great strength 
 
 is refjuire<l it is not as good as those alread\- mentioned, as the 
 
 facing has i>een weakened to a certain extent by enlarging the 
 pin-holes. 
 
350 REPAIRING CROWNS AND REPLACING BROKEN FACINGS 
 
 Dr. Emory A. Bryant has a novel method of attaching a new 
 facing. A tap and die, the size of the tooth-pins are necessary, 
 together with a special countersinking tool and a screw-driver. The 
 pins are cut from the old backing and holes the size of the pins of 
 the new facing are drilled in proper positions. With the counter- 
 sinking tool held in a right angle hand-piece, the holes are counter- 
 sunk on the lingual side nearly to the outer wall of the backing. The 
 nuts are made to correspond in size and taper with the counter- 
 sink. By means of the oiled die, a thread is cut on each pin of 
 the facing, and continued to the back of the facing, exercising great 
 care that the pins are not twisted or stained. The backing is 
 covered with cement, the facing set in position and each nut is 
 loosely adjusted, then alternately screwed into place drawing the 
 facing close to the backing. The protruding portions of nuts and 
 pins are then ground flush with the backing and polished. 
 
 This method of replacing broken facings is very ingenious and 
 will answer where there is little or no strain on the facing, but 
 the cutting of a thread, on such a small pin, will weaken it to 
 such an extent as to render it of little value where much strength 
 is required. It is better if the full strength of the pin can be 
 preserved. 
 
CHAPTER XVII. 
 
 BRIDGE-WORK DPISIGXED FOR RIGCJVS DISEASE 
 CONDITIONS. 
 
 By HOWARD T. STEWART, D.D.S., 
 
 NEW YORK CITY. 
 
 The attachments partially illustrated below, is the outgrowth of 
 the system of the split pin and telescope crown as taught by Dr. 
 Peeso (in his construction of modern removable bridge-work), to 
 whose teachings I owe my early inspiration. 
 
 On studying closely the crowns, we will see that the original 
 idea of the split pin and telescope crown obtains through the entire 
 work. Even the split bar is the suggestion of the split pin, and 
 the "shoulder crowns" are a modification of the telescope crown. 
 
 This system was gradually worked out by the writer, in his 
 efforts to adapt bridge-work to those conditions of alveolar inflam- 
 mation where special care is required to produce permanent results. 
 
 As my own work differs to a certain extent as to the individual 
 lines above referred to, from any other system, I am giving this 
 in addition to what Dr. Peeso has already presented, in the hope 
 of having it contribute somewhat to this characteristic individuality. 
 
 Fig. 041 illustrates attachments made of telescoijcs and split 
 bars, also an adjustable saddle. This saddle is attached temporarily 
 with gutta-percha or cement, removed and lowered as absorption 
 of the ridge takes place. This prevents rocking of bridge and 
 leverage on roots. 
 
 Fig. 042 is a full upper with rubber saddles. These saddles arc 
 sometimes made of rubber (always perfectly smooth and highly 
 polished next to the gum), and as the ridge absorbs, wax is added, 
 patient bites on it and more rubber is added. This can be repro- 
 ducer! in gold later. 
 
 The cuspid shows the usual tube in canal with a short tube swung 
 off that just clears the gum. This makes a firmer locking device 
 than the one pin. 
 
 Tlic (•(•ntnil is llic nsn;il lube Nhglitly Iciigt linn d up into (lie 
 b(»d\' ()\ rruwii. 
 
352 BRIDGE-WORK DESIGNED FOR RIGG'S DISEASE 
 
 Fig. 641 
 
 Fig. 642 
 
BRIDGE-WORK DESIGNED FOR RIGG'S DISEASE 353 
 
 The first hicuspkl tube extends well into the erowii, giving 
 longer pin and additional strength and friction. 
 
 The second bicuspid shows one tube in the canal and one short 
 tube stopping at the cap, this last tube being the length only of 
 the box in the crown. 
 
 Fio. G4:i 
 
 Fig. 043 is a case often |)rcsenting itself cs[)ccialiy in Kigg's 
 disea.se mouths. Here the important feature is the palatal bar. 
 The writer was, so far as he knows, the first to utilize these l)ars 
 in bridge-work. After years of experiment, he finds the proper 
 place for these bars to be very far back usually near the junction 
 of the .soft and hard palate. There is no m<'clianical advantagt; 
 in placing these forward (as is usually donr) not pos.sessed by those 
 placed well back and here tlie\' do nol interfere with the 1()ngu<; 
 when properly ((instructed. Note liow in mastication this bar 
 2.'} 
 
354 BRIDGE-WORK DESIGNED FOR RIGG'S DISEASE 
 
 overcomes leverage in three different directions, and it is at once 
 apparent how very useful it would be where the alveolar process 
 about the abutments was partially absorbed. This bar is made 
 by flowing 20-carat solder on pure gold. The solder naturally 
 assumes a rounded shape approximating a proper form next to the 
 tongue. The lower bar is shaped thick at the bottom (to give it 
 rigidity and so as to be rounded and blunt to the frenum), and 
 thin at the top so as not to be noticed by the tongue. Rigidity 
 is extremely important to overcome the leverage in both upper 
 and lower bars. The first bicuspid in Fig. 643 shows two short 
 tubes neither of which enter the canal. Room is left for the por- 
 celain on the buccal side of the caps. 
 
 Fig. 644 
 
 Fig. 644 shows a case where all but seven teeth were lost from 
 Rigg's disease. It will be noted that in this case (as in all the 
 others) each abutment stands alone — no two are fastened together. 
 In this way when the bridge is removed, a silk thread can be carried 
 all around each abutment, beneath the gum; and this is important 
 to prevent a return of peridental troubles. Each tooth also gets 
 some individual motion in brushing and massaging. 
 
 The molar and bicuspid on the right show a modification of the 
 
BRIDGE-WORK DESIGNED FOR RK.'G'S DISEASE 355 
 
 same attachments shown in Fiys. ()42 and 04;). These are longer 
 and present more friction. 
 
 The bicuspid on the left shows another form of the split bar. 
 It is not really a split bar, but two pieces of clasp metal soldered 
 to a boxing at opposite ends. That is where one clasp metal bar is 
 soldered, the other bar is a loose end. In other words, where in the 
 other attachment the two pieces of clasp metal are soldered together 
 at the same end of the boxing, these are soldered separately in the 
 boxing at opposite ends. P^ach end of the boxing thus having 
 one piece of clasp metal soldered to its wall. 
 
 Fi(i. 045 
 
 Fig. ()44 shows two small tubes swung off tiic side of a crown. 
 These can be used where it is desirable to place the attachment 
 on the side of a crown instead of within it. One tube is sometimes 
 sufficient. This may be attached to inlays. 
 
 The dummy shows four si)lit pins to fit the foiu- tubes soldered 
 tf) the two adjoining crowns. 
 
 The molar in Fig. (■»4(1 is the strongest of all attachnicjits the 
 writer has devised. Its chief application is in the upper arch 
 where the bite is very short and where much of the bridge has to 
 be supported by this single attachment. In this single crown 
 it looks bulky but in a bridge this extension is incorporated into 
 the dummy adjoining. Note the reinforcement of the clasp metal 
 at tlx- soldered ends to give it additional strength. 
 
 The bicuspid shows how this split bar may be used when the end 
 of a bridge is on a bicusj)id root that w ill not receive a tube. The 
 cus[>id shows attaclnneni much like tli.if of the left bicusf)id in 
 Fig. HH. 
 
 The bicuspid on the left side of I''ig. (Ill .-ln»\\> t lie ;it laclunenl 
 extcn<ling off both sides <'(|ually. Here was needed a large friction 
 surface. This attachment dill'ers from all the others in that instead 
 of having the two pieces of e|;l^p metid free at the same end, they 
 
356 
 
 BRIDGE-WORK DESIGNED FOR RIGG'S DISEASE 
 
 are free at opposite ends. Thus where one is free, the other is 
 soldered. This gives a more equal pressure all along — not as the 
 other bars do or as a split-pin does. 
 
 The writer originated this form of attachment (the "split-bar") 
 and has been demonstrating it at dental conventions in its various 
 forms for about nine years. It is capable of a great variety of forms 
 and applications. The original mechanical principle of this bar is 
 the same as the split-pin as taught by Dr. Peeso. 
 
 •^ 
 
 Fig. 646 
 
 This, system in its present form was gradually evolved to be 
 especially adapted to Rigg's disease conditions, but is, of course, 
 equally applicable to any condition. 
 
 On studying these attachments closely one will see an astonish- 
 ing amount of friction surface presented — the two pieces soldered 
 to the cap being entirely boxed in beside the clasp metal running 
 between. One end of the bar is, of course, free, alloM^ng the two 
 pieces to be spread just as the split pin is. 
 
 Space here forbids a detailed account of the construction of the 
 various forms of these attachments, each of which must be adapted 
 to the needs of the individual case. 
 
CHAPTER XVIII. 
 
 DENTAL METALLURGY.! 
 
 (loLD WD ns Ali.oys, Including Refractohy Materials 
 AND Fluxes. 
 
 By Louis J. Weinstein. 
 
 In the preparation of this contribution, it has been the aim of 
 the author to present a brief and practical, rather than an academic 
 discussion of the subject. 
 
 In addition to a consideration of the gold alloys, it was found 
 ad\isable to include a section on the closely-allied and important 
 subjects of refractory materials and fluxes used in connection with 
 gold, during soldering or casting operations. 
 
 The series of investigations, upon which this contribution is 
 based, was started during the year 1908, when in attempting to 
 use the coin gold and modifications of same in the form of solders, 
 he was seriously handicapped by the comparatively low melting 
 point of the coin gold, and the inadequacy of the other gold alloys 
 usually ol)tainable, which, to the man of exceptional ability, is not 
 so apparent as to one of average, or even less than average skill. 
 
 In \iew of the well-known fact that platinum is a metal that 
 could be alloyed with gold to increase the melting i)oint of the 
 latter, a number of experiments were ma<le to produce a fornnila 
 for a gold alloy sufficiently high in melting point, so that the general 
 practitioner could use it as a sul)stitute for coin gold, and therein 
 (eliminate the process of "sweating," and instead, solder the result- 
 ant high-fusing gold witli other gold of a melting point ((inal to 
 that of 24- or 22-K. and thus obtain a strong union that wonid 
 withstan<l tl)e subscfjuent, and often numerous, soldering opera- 
 tions required for the completion of the case. 
 
 The alloys finally developed were found so satisfactory, that 
 it is not too much to say that even in the hands of the skilled 
 oiK'rator these alloys will prove of considerable value, if for no 
 (»ther reason than the very great differenee in the melting |)oiftt 
 
 ' Copyritrlil M)Hi, Ijy Loiii.s .1. Wi-inslcin. All rinlilK rcHcr\ci|. 
 
358 DENTAL METALLURGY 
 
 between the highest and lowest fusing alloys in the series, and 
 the consequent increased facility and safety during the necessary 
 subsequent soldering operations. 
 
 In the author's efforts to obtain information from which to for- 
 mulate alloys, he was greatly handicapped, inasmuch as there were 
 no dental publications bearing to any extent on the subject. After 
 a thorough study of the then recently revised books on dental 
 metallurgy, a number of experiments were made, the results of 
 which did not appear to correspond with the data in the text-books. 
 A number of works on general metallurgy were consulted, and 
 found to differ materially with the dental text-books in a great 
 many instances, particularly on data concerning the behavior of 
 the binary alloys of gold and silver, gold and platinum, etc. In 
 order to establish a definite foundation upon which to base further 
 researches, the author proceeded to make a series of binary alloys, 
 and from the resultant data was enabled to proceed with the 
 development of more complex alloys. 
 
 The resultant formulae given herein have been in practical use 
 for a period ranging from three to six years, and while the author 
 does not claim that his is by any means the last word on the sub- 
 ject, he trusts that the results of his research will prove of some 
 immediate benefit to both advanced students and practitioners. 
 
 The author takes this opportunity of thanking Drs. Edwin W. 
 Harlan, Frederic A. Peeso, James H. Prothero, William S. Prensky, 
 Mr. Harry C. Ney and other friends for their kind encouragement 
 and aid. 
 
GOLD AND ITS ALLOYS 
 
 359 
 
 TABLE Xo. I.— THE MELTING POINTS' AND DENSITIES OF METALS. 
 
 
 Name of metal. 
 GOLD 
 
 Symbol. 
 Au 
 
 Melting 
 point, ° F. 
 
 1945 
 
 Melting 
 point, ° C. 
 
 1063 
 
 Density. 
 19.3 
 
 Gboup 
 
 I.— Silver 
 
 Ag 
 
 1761 
 
 960 
 
 10.5 
 
 
 Copper 
 
 Cu 
 
 1981 
 
 1083 
 
 8.9 
 
 
 Platinum 
 
 Pt 
 
 3190 
 
 1755 
 
 21.5 
 
 
 Palladium 
 
 Pd 
 
 2820 
 
 15.50 
 
 11.4 
 
 Group 
 
 II. — Iridium 
 
 Ir 
 
 4170 
 
 2300 
 
 22.5 
 
 
 Osmium 
 
 Os 
 
 4900 
 
 2700 
 
 22.5 
 
 
 Rhodium 
 
 Rh 
 
 3525 
 
 1940 
 
 12.1 
 
 Group 
 
 III.— Zinc 
 
 Zn 
 
 787 
 
 420 
 
 7.1 
 
 
 Cadmium 
 
 Cd 
 
 610 
 
 .321 
 
 8.6 
 
 
 Tin 
 
 Sn 
 
 450 
 
 232 
 
 7.3 
 
 
 Aluminum 
 
 Al 
 
 1218 
 
 658 
 
 2.7 
 
 Group 
 
 IV.— Nickel 
 
 Ni 
 
 2646 
 
 1452 
 
 8.9 
 
 
 Cobalt 
 
 Co 
 
 2714 
 
 1490 
 
 8.7 
 
 
 Manganese 
 
 Mn 
 
 2237 
 
 1225 
 
 7.4 
 
 
 Chromium 
 
 (> 
 
 2750 
 
 1510 
 
 6.9 
 
 
 Tantalum 
 
 Ta 
 
 5160 
 
 2850 
 
 14.5 
 
 
 Tungsten 
 
 W 
 
 5430 
 
 3000 
 
 18.7 
 
 
 Molybdenum 
 
 Mo 
 
 4500 
 
 2500 
 
 8.6 
 
 
 Vanadium 
 
 V 
 
 3150 
 
 1730 
 
 6.1 
 
 
 Titanium 
 
 Ti 
 
 3450 
 
 1900 
 
 4.5 
 
 The elements following gold have been divided into four groups. 
 This division is an arbitrary one, and made solely for the purpose 
 of facilitating future references. 
 
 • The melting points are afcording to the latest data i)ul)li.shed by the l'. S. Hureau 
 Standard.s. 
 
360 DENTAL METALLURGY 
 
 BINARY ALLOYS. 
 
 It is a well-known fact that pure gold has but a limited use in 
 the construction of various dental appliances, and that it is neces- 
 sary to alloy it with various other metals, in order to increase its 
 durability, hardness, and tenacity, and to vary the melting point 
 above or below that of pure gold, as may be required. The metals 
 in common use for this purpose have been copper, silver, and 
 platinum, the latter to a limited extent, also zinc, cadmium, etc., 
 for solders, which, of course, require a considerably lower melting 
 point than the gold upon which they are to be used. 
 
 A thorough knowledge of the properties of the simple binary 
 alloys is of paramount importance, because these properties almost 
 invariably give an indication of what may be expected from more 
 complex alloys. 
 
 It is generally accepted by metallurgists that binary alloys of 
 gold and silver, copper, platinum, or palladium, form solid solutions, 
 that is, solutions of one metal in another, if in proportions within 
 certain limits. Such binary alloys as will be discussed, form solid 
 homogeneous solutions, except when otherwise noted. 
 
 It is unnecessary to enter into an academic discussion of the 
 possible molecular affinity existing among various elements or 
 of eutectics, formed between the metals in the binary alloys that 
 will be considered, because such compounds or mixtures do not 
 occur in such alloys as may be considered fit for use in the mouth. 
 For example, alloys of gold and copper in the proportion of 82 
 per cent, gold to 18 per cent, copper form a eutectic which is the 
 lowest fusing of the gold copper series, and when more than 18 
 per cent, copper is present, the copper is not in uniform solution 
 and segregates. As the alloys containing over 15 per cent, copper 
 are extremely brittle and ununiform, no binary alloys containing 
 more than 10 to 12 per cent, copper will be considered. In other 
 words, alloys of gold and copper, where copper does not exceed 
 12 or 13 per cent., do not form any compounds with special charac- 
 teristics. 
 
 To simplify the references to ternary, quaternary, or more 
 complex combinations of metals, alloys of two metals will be 
 termed, as is customary, "binary," but the alloys composed of 
 three or more metals will be termed "complex" alloys. 
 
 Gold and Silver. — Silver is commonly utilized as an alloying 
 element with gold. It is used, to a considerable extent, as part of 
 
BINARY ALLOYS - 361 
 
 tlie aik»y in dental gt)l(ls, and, as will be shown later, principally 
 as a eheai)ening agent. 
 
 There seems to prevail generally an erroneous opinion regarding 
 the properties of silver-gold alloys. It has been stated^ that silver 
 is used to harden and lower the melting point of gold. This deduc- 
 tion is distinctly contrary to the results obtained by the author. 
 After making a number of binary alio} s, it was proved that even 
 the maximum percentage that may be used in dental work, say 
 25 per cent, of sih'er to 75 per cent, of gold, does not confer any 
 perceptible hardness upon the gold, neither does it lower the melting 
 point to such an extent that the difference could be measured with 
 a pyrometer. 
 
 Practically the only effect silver (even if present to the extent 
 of 25 per cent.) has upon gold, is to discolor the gold, making it 
 greenish, and lower the specific gravity, thus increasing the volume. 
 It will thus be seen that silver confers no special benefit upon gold, 
 except cheapening it and acting as a color modifying agent. On 
 the other hand, it may prove detrimental, as a considerable propor- 
 tion of silver may interfere with the action of other alloying elements 
 when attempting to produce si complex gold alloy, and also on 
 account of the strong affinity that oxygen and other gases possess 
 for silver. It will thus be readily seen that small percentages may 
 sometimes be used to advantage as a color-modifying agent, but 
 a large percentage of silver is distinctly contraindicated. 
 
 Silver, in such proportions as may be needed for dental golds, 
 alloys uniformly and without difficulty, and may be depended upon 
 to remain in uniform distribution. 
 
 The author has found that gold alloys, with a high percentage 
 of silver, when remelted and cast, show in the casting a consid- 
 erable variation of the silver content which indicates that a jiartial 
 separation takes place. This has not been investigated further 
 for tlie reason, that castings of gold with a high percentage of 
 silver have no practical application. As stated before, small i)er- 
 centages of silver have ])racti(ally no effect upon the gold and 
 this fact has been taken advantage of, for a considerable period of 
 time, by at least one manufacturer, who alloys pure gold with from 
 1 to 2 per cent, of silver, and sells it as 24-I\. This alloy appears 
 •SO similar to pure gold that the ordinary eye is decei\ed and the 
 unprincipled manufacturer is the gainer. 
 
 ' IvHwiK'n MctalluFKy (Kofiiig'.i rcv'itiion), \t. Ili.'i; (loiliicn'.-i Mclalliiiny ( Milhfiry'.s 
 rovi.-iioii), ]>. 278. 
 
362 
 
 DENTAL METALLURGY 
 
 Fig. 647 illustrates the melting point curve of gold silver alloys. 
 
 Practically the same determination appears in very recent works 
 on metallurgy.^ 
 
 Silver-platinum alloys have been used, to a considerable extent, 
 for crown posts, dowels, backings, etc. As a rule, alloys of this 
 character (20 to 30 per cent. Pt.) are extremely unsatisfactory, 
 both during their manipulation, and in ultimate service, and their 
 use should be avoided. They are somewhat improved with higher 
 
 Fig. 647. — Melting Points of Alloys of Gold and Silver. 
 
 2050 
 
 2000 
 
 1950 
 
 1900 
 
 1850 
 
 1T50, 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ~^' 
 
 ^-. 
 
 »^ 
 
 
 
 
 
 
 
 
 
 
 N 
 
 \ 
 
 
 
 
 
 
 
 
 
 
 N 
 
 \ 
 
 
 
 
 
 
 
 
 
 
 \ 
 \ 
 
 ' 10 :» 30 40 50 80 70 80 90 100 
 Percentage of Silver. 
 
 5 per cent. Ag, melting point 1945° F., 1063° C. 
 10 " Ag, " " 1945° F., 1063° C. 
 
 15 " Ag, " " 1943° F., 1062° C. 
 
 30 " Ag, " " 1942° F., 1061° C. 
 
 percentages of platinum or palladium, but the alloys are extremely 
 ununiform and still quite soluble in acids and apt to discolor and 
 corrode. The cost with more platinum is considerably higher and 
 even then the alloys are not equal to a fair grade of alloyed gold, 
 either in usefulness, or economy. 
 
 Gold and Copper. — Copper is one of the most commonly used 
 and most useful alloying elements. It confers hardness and elasticity 
 upon gold, but is detrimental when used in large proportions, on 
 account of its great tendency to lower the melting point of the 
 alloy, and the strong oxidation and brittleness of the alloys. 
 The copper is in high proportion. It is, however, a most useful, 
 
 1 Fenchel's Metallurgy. 
 
BINARY ALLOYS 
 
 363 
 
 aiul in fact an iiidispcihsdhU' alloying element, if employed judi- 
 ciously. Alloys of gold and copper, such as U. S. coin gold (An. 
 90- Cu 10), ha^•e been used with most satisfactory results both 
 from the standpoint of durability and resistance against the oral 
 fluids. An alloy of this character is ideal for crown work, except 
 for the disadvantage of its low melting point, which is caused by 
 the copper content and its range of usefulness is therefore limited, 
 
 Fig. 648. — Melting Points of Alloys of Gold and Copper. 
 
 aooo 
 
 lavi 
 
 1900 
 
 1850 
 
 1750 
 
 1700 
 
 1650 
 
 1600 
 
 
 
 
 
 
 
 
 
 
 / 
 / 
 
 \ 
 
 
 
 
 
 
 
 
 / 
 
 / 
 
 \ 
 
 
 
 
 
 
 
 
 / 
 
 / 
 / 
 
 
 \ 
 
 
 
 
 
 
 
 
 
 
 \ 
 
 
 
 
 
 / 
 
 / 
 
 
 
 
 
 \ 
 
 
 
 / 
 
 y 
 
 
 
 
 
 
 \ 
 
 
 
 y^ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 :«) to :*) m 
 Percentage of Copper. 
 
 00 
 
 100 
 
 5 per cent. Cu, mcltinK point 1S40° F., 1004° C. 
 10 " Cu, " " 1735° F., 1)46° C. 
 
 15 " Cu, " " 1690° F., 921° C. 
 
 18 '• Cu, " " 1661° F., 90.5° C. 
 
 even in the hands of the skilled operator. This inadequacy, as will 
 be shown later, can be corrected by sub.stituting platinum, etc., 
 for some of the copjxT, thus raising the melting j)()int, and reducing 
 oxidation, without changing the valuable properties the coin gold 
 possesses; namely, strength and durability. 
 
 Fig. (548 illustrates the melting point curve of gold-copixT alloys. 
 As will be seen from the chart, the melting point of pure gold drops 
 rapidly upon the addition of copper; ."> |)cr cent, copper lowers the 
 melting point ab(»u1 100'^ |'\; 10 |)er cent. co|)|)er lowers tlie melting 
 
364 DENTAL METALLURGY 
 
 point of gold about 200° F.; 15 per cent, copper lowers the melting 
 point about 250° F. ; and 18 per cent, causes a drop in melting point 
 of about 300° F. As will be seen from the illustration, the lowest 
 melting point between gold and copper is when 18 per cent. cu. is 
 present. The addition of more than 18 per cent. cu. causes a rise 
 in melting point until the melting point of copper, 1980° F. is 
 reached. 
 
 x\s mentioned previously, it is advisable to limit the total copper 
 content to 10 or 12 per cent. Consequently, if the melting point 
 of an alloy of gold and copper of requisite strength and hardness 
 is too low, it is necessary to use platinum or palladium to bring it 
 to the point desired. 
 
 The valuable properties of copper as a hardening agent have 
 apparently been underestimated, and not given sufficient considera- 
 tion by writers, but taken advantage of by manufacturers, as will 
 be noted in the composition of commercial clasp metals. 
 
 Gold and Platinum. — Platinum is being used to some extent 
 as an alloying element with gold, principally for clasp metal, etc. 
 It has been stated that platinum confers great elasticity and hard- 
 ness upon gold, which appears correct only to a limited extent. 
 The author's experiments have indicated that platinum has com- 
 paratively little effect as a hardening agent upon gold. It does, 
 however, raise the melting point considerably, as will be shown 
 later. 
 
 Platinum is much inferior to copper as a hardening agent. This 
 is readily proven upon an examination of a binary alloy of gold and 
 copper containing 10 per cent, copper, and a binary alloy of gold 
 and platinum containing 25 per cent, platinum (so-called platinum 
 solder). A comparison of two pieces of equal dimension will show 
 that the gold-copper alloy, with 10 per cent, copper is quite as 
 hard and elastic as the gold alloy with 25 per cent, platinum, and 
 more uniform. It is therefore evident that platinum is not the 
 most suitable hardening agent, and its range of usefulness as an 
 alloying element is therefore limited. 
 
 Platinum, however, is an excellent adjunct to copper, as it tends 
 to raise the melting point, which is lowered sensibly by any con- 
 siderable percentage of copper. 
 
 Fig. 649 illustrates the melting point curve of gold-platinum 
 alloys. 
 
 Large percentages of platinum cannot be alloyed uniformly with 
 gold, and in order to insure a uniform alio}', it is not advisable to 
 
BIXARY ALLOYS 
 
 865 
 
 use more than .") to 10 per cent, in a binary alloy and 10 to lo per 
 cent, in a complex alloy. In the latter, the other alloying dnueuis 
 help to hold the ylatimnn in uniform distribution. If it is desired 
 to raise the melting point of an au,-cu. alloy higher than 5 to 10 
 
 Fig. 649. — Melting Points of Alloys of Gold and Platinum. 
 
 •z'm 
 
 zm 
 
 2100 
 
 2J50 
 
 2300 
 
 2:ij0 
 
 2:A)0 
 
 21.)0 
 
 2100 
 
 2(i.>() 
 
 2t)iK) 
 
 I'.XK) 
 
 
 
 
 
 
 -^ 
 
 
 y 
 
 
 
 
 
 • 
 
 
 
 
 
 
 /■ 
 
 
 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 III ;.'o :jo III .-,1 
 
 I'crccntufjc of I'lutiniun. 
 
 .") pcrcciil. I'(, iiiclliim poiiil 2U\')° !•'., I 102° C. 
 
 10 " I'l, •• " 20S0^' F., 1141° C. 
 
 1'' ■' I't. " •■ iiior>° F., ii(irj° c. 
 
 ^" " I't. " " 22«0° F., 122S° C. 
 
 per cent, plalinuni makes possible, il is ad\ isahlc to use ixdhuliuni, 
 which cotuhines jjerfectji/ in l.otji the liiimrx and complex alloys that 
 will l)c consirlcrcd. 
 
366 
 
 DENTAL METALLURGY 
 
 Gold and Palladium. — Palladium is as yet a comparatively rare 
 metal. It has been used to some extent in the industries and arts, 
 but practically to no extent in dental golds. Palladium is a metal 
 very similar to platinum except for its specific gravity, 11.4, which 
 
 Fig. 650. — Melting Points op Alloys of Gold and Palladium. 
 2500 
 
 2450 
 
 2400 
 
 2350 
 
 2300 
 
 2250 
 
 2200 
 
 2130 
 
 2100 
 
 2030 
 
 2000 
 
 1950 
 
 1900 
 
 
 
 
 
 / 
 
 / 
 
 / 
 
 
 
 
 / 
 
 / 
 / 
 
 
 
 
 
 / 
 
 / 
 
 / 
 
 / 
 
 
 
 
 
 / 
 
 / 
 
 / 
 
 
 
 
 
 
 / 
 
 
 
 
 
 / 
 
 
 
 
 
 
 / 
 
 
 
 
 
 
 / 
 
 
 
 
 
 / 
 
 
 
 
 
 
 / 
 
 
 
 
 
 
 / 
 
 
 
 
 
 
 
 
 
 
 
 
 10 ;30 30 40 50 
 
 Percentage of Palladium. 
 
 60 
 
 5 per cent. Pd, melting point 2060° F., 1127° C. 
 10 " Pd, " " 2145° F., 1174° C. 
 
 15 " Pd, " " 2250° F., 1232° C. 
 
 20 " Pd, " " 2.340° F., 1282° C. 
 
 is considerably lower than platinum, and its melting point, which 
 is also considerably lower than that of platinum. 
 
 It has been stated that palladium makes gold brittle. This is 
 contrary to the author's findings. More than twenty-five difl^'erent 
 
BINARY ALLOYS 307 
 
 alloys were made containing from 1 to 30 per cent, palladium. 
 All of them appeared quite uniform and remarkably malleable, 
 ductile and tenacious. 
 
 Palladium also forms excellent uniform alloys with copper, 
 silver, etc., and it is a very valuable adjunct to platinum in complex 
 gold alloys. Its use, however, is limited, on account of the fact 
 that it exerts a strong decolorizing action upon gold, 3 to 5 per cent, 
 turning gold sensibly lighter, and 15 to 20 per cent, almost white 
 (platinum color). 
 
 Fig. (ioO illustrates the melting point curve of gold-palladium 
 alloys. 
 
 Another remarkable and most valuable property that palladium 
 possesses, is the fact that although the melting point, 2820° F. 
 (1550° C), is considerably lower than that of platinum, a given per- 
 centage of palladium (by weight) will increase the melting point 
 of gold more than an equal amount of platinum, and in view of the 
 fact that platinum in considerable percentages does not alloy 
 uniformly with gold, it is well to use palladium, as it alloys uni- 
 formly with gold in all proportions. Therefore in alloys where 
 color is no object palladium may be incorporated to very great 
 advantage. 
 
368 DENTAL METALLURGY 
 
 TABLE II.— MELTING POINTS OF BINARY ALLOYS. 
 
 GOLD— SILVER. 
 
 Melting point of gold 1945° F., 1063° C. 
 
 silver 1761° F., 960° C. 
 
 gold, 95 per cent., silver, 5 per cent. . 1945° F., 1063° C. 
 
 gold, 90 " silver, 10 " 1945° F., 1063° C. 
 
 gold, 85 " silver, 15 " . . 1943° F., 1062° C. 
 
 gold, 70 " silver, 30 " . . 1942° F., 1061° C. 
 
 GOLD— COPPER. 
 
 Melting point of gold 1945° F., 1063° C. 
 
 ' ■ " copper •. 1980° F., 1083° C. 
 
 gold, 95 per cent., copper, 5 per cent. . . 1840° F., 1004° C. 
 
 gold, 90 " copper, 10 " . . 1735° F., 946° C. 
 
 gold, 85 " copper, 15 " . . 1690° F., 921° C. 
 
 " . gold, 82 " copper, 18 " . . 1661° F., 905° C. 
 
 GOLD— PLATINUM. 
 
 Melting point of gold 
 
 " " platinum . 
 
 " " gold, 95 per cent., platinum, 5 per cent. 
 
 " " gold, 90 " platinum, 10 " 
 
 " " gold, 85 " platinum, 15 " 
 
 " " gold, 80 " platinum, 20 " 
 
 1945° F. 
 
 1063° C 
 
 3190° F. 
 
 1755° C 
 
 2015° F. 
 
 1102° C 
 
 2085° F. 
 
 1141° C 
 
 2165° F. 
 
 1165° C 
 
 2260° F. 
 
 1228° C 
 
 Me 
 
 GOLD— PALLADIUM. 
 
 ting point of gold 
 
 " palladiuin 
 
 " gold, 95 per cent., palladium, 5 per cent. 
 
 gold, 90 " palladium, 10 
 
 ■ " gold, 85 " palladium, 15 " 
 
 gold, 80 " palladium, 20 
 
 1945° F. 
 
 1063° C 
 
 2820° F. 
 
 1550° C 
 
 2060° F. 
 
 1127° C 
 
 2145° F. 
 
 1174° C 
 
 2250° F. 
 
 1232° C 
 
 2340° F. 
 
 1282° C 
 
BINARY ALLOYS 'MJ 
 
 Gold and Metals in Group 2. — Iridium. — Iridio- platinum is 
 usually employed in place of pure platinum on account of its greater 
 hardness and durability. When experimenting with the series of 
 binary alloys previously discussed, it naturally suggested itself 
 to the author, that gold alloyed with iridio-i)latiiuim, instead of 
 pure platinum, would prove superior. A number of alloys were 
 attempted and the results obtained were found invariably inferior 
 to alloys of gold and pure platinum. The unsatisfactory results 
 should have been anticipated because it is well known that iridium 
 will not alloy with gold uniformly, but segregates on account of 
 its extremeh- high melting point and high specific gravity. It is 
 quite certain that in attempting to make the alloy, the following 
 occurred: When the iridio-platinum was brought into the gold, 
 the heat used was sufficient to melt the platinum and set free the 
 particles of iridium which did not go into solution with the gold 
 platinum mixture, but suspended, and then segregated practically 
 in the same way as if free iridium were added to gold without 
 the presence of the platinum. 
 
 The experimental alloys were made of pure gold and 15 per cent, 
 iridio-platinum, and compared with alloys made of pure gold and 
 15 per cent, platinum. On rolling both to equal gauge, polishing 
 and etching, the gold-platinum alloy was found quite uniform, 
 whereas some sections of the gold iridio-platinum alloy were harder 
 and higher fusing, while other sections were softer and lower fusing 
 than the gold-platinum alloy. In addition, all the gold-platinum- 
 iridium mixtures appeared streaky and ununiform, even to the 
 naked eye, while the gold-platin\nn alloys appeared almost perfect 
 even under the microscope. 
 
 Numerous other experiments were made, along these lines, and 
 in spite of the fact that some have advocated the use of iridio- 
 platinum instead of pure platinum in alloys, it is the author's con- 
 clusion that pure platinum is far superior to iridio-platinum as an 
 alloying element with gold. 
 
 Osmium. — No attempts have yet been made to foi-ni alloys with 
 osmium, as it is even higher fusing than iridium and therefore poor 
 results may Ix- anticipated. The author expects, however, to 
 experiment with osmium shortly, to determine if there is any 
 possible benefit to be derived from it, because alloys of Os Vt 
 are claimed to be superior to alloys of Ir l*t.' 
 
 ' !•■. ZimiinTiiiaii, All'iv ot I'hilinimi :iii(l O.siiiiuiii. I'.S. I'.ilml No. lO.').'), 11!). 
 24 
 
370 DENTAL METALLURGY 
 
 Rhodium. — Rhodium is another metal of the platinumi group that 
 will prove of considerable benefit if sufficient of it could be obtained 
 at a moderate cost. It is quite similar to palladium. It also has a 
 low specific gravity, 12.1, and is considerably higher fusing than 
 platinum (according to U. S. Bureau of Standards), 
 
 The author has not experimented with il in the pure state, but 
 procured a quantity of it in the form of platinum containing 10 
 per cent, rhodium. This platinum-rhodium alio}' was used for a 
 considerable time instead of pure platinum. The alloys were quite 
 satisfactory, but the advantages over pure platinum as an alloying' 
 agent are so slight, and the cost so high, that it appeared advisable 
 to discontinue its use at the time. 
 
 Gold and Metals in Group 3. — (See under Gold Solders.) • 
 
 Gold and Metals in Group 4. — Sometime after the introduction 
 of the casting process, it became apparent that in order to utilize 
 the casting process to advantage, alloys other than ordinarily 
 obtainable would have to be made in order to insure satisfactory 
 results. The ordinary plate golds obtainable, when cast in small 
 bulk, were too soft and frail, and the sections had to be cast larger 
 and heavier than normal, and were therefore objectionable. 
 
 A number of experiments were made in attempting to cast the 
 various clasp metals, and the results obtained were very unsatis- 
 factory. At this time began to appear literature regarding indus- 
 trial alloys both ferrous and non-ferrous, with the so-called rare, 
 or little known, metals, such as nickel, cobalt, manganese, tungsten, 
 vanadium, etc., enumerated in the table of elements under Group 4. 
 
 Some remarkable results were obtained in various industrial 
 steels, brasses, and bronzes, and it was not unreasonable to expect 
 that some of these rare metals could be utilized to advantage in the 
 formation of gold alloys for casting purposes. 
 
 In view of the fact that there was no precedent to follow and no 
 literature obtainable on the relation of these metals to gold, it can 
 readily be understood that the author's attempts to alloy these 
 rare metals with gold were more or less empirical, and the results 
 obtained w^re no better than should have been anticipated. Meet- 
 ing with such poor success, the author proceeded with the series 
 of researches into both the binary and complex alloys of gold with 
 the elements in groups one, two and three and the resultant for- 
 mulae developed are given herein in the following pages. 
 
 Since then, a number of experiments have been made by other 
 investigators, in attempting to utilize some of the rare metals such 
 
A NEW SKRIES OF ALLOWS 
 
 •1 
 
 as nickel, tungsten, molybdenum, titanium, etc., as substitutes for 
 iridio-platimmi. Tlie results so far lia\e not i)roved successful. 
 
 This non-success will not appear strange to those familiar with 
 both the chemical and physical characteristics of the elements 
 mentioned. Unless some radical method of handling these metals 
 IS evolved iridio-platinum will contimie to retain the position it 
 occupies (.see elastic gold under clasp metals). 
 
 The author has not by any means given ny hope of the possible 
 utilization of some of the rare elements in eonneetion with alloys for 
 casting. He is now engaged in a series of experiments which have 
 already shown promising results and he hopes to have data of 
 importance available for publication in the near future. 
 
 A NEW SERIES OF ALLOYS. 
 
 From the preceding data on the i)roj)erties of the binary alloys 
 of gold with the metals in (Iroup 1, certain conclusions may be 
 drawn and data obtained, and it then becomes a comparatively 
 simple matter to form complex alloys for our requirements. Before 
 proceeding to formulate a comi)lex alloy, it will be well to consider 
 again the hardness conferred upon gold by the metals in (Jroup 1. 
 
 Ji 
 
 /00% Au 
 
 AuJff 
 
 90ZA>j -/07oAff 
 
 Au-Fd 
 
 00%Au-/OZ/M 
 
 Au-jft 
 
 9oroAu-/07.re 
 
 Au-Cu 
 
 ^OZ A,, 
 
 Fic;. fi,51. — CoiMpMi-.-ifivc h:irfliiOF8 of liiuMr.s :ill.,ss. 
 
 As Will be s<-cn from j-'ig. (mI, pure silver lias piaetieally no elleet 
 on gold as far as increasing its liardiiess. Palladium has soiii(> 
 hardening properties, and it is well to be;ir (!,;,» in mind when h.r- 
 
372 DENTAL METALLURGY 
 
 mulating an alloy. Platinum has considerably more hardening 
 power than palladium and is a factor, but copper is the most 
 valuable agent of them all, and in proceeding to formulate the com- 
 plex alloys, we must consider the copper as the principal hardening 
 agent and the others as adjuncts. 
 
 Gold for Crown, Bridge and Plate Work.— Gold Plate No. 1.— 
 Bearing in mind the hardening power, and the effect on melting 
 point produced by the alloying elements, let us consider such a 
 formula as the following: 
 
 FORMULA OF GOLD PLATE No. 1. 
 
 Per cent. 
 
 Gold . 88.0 
 
 Platinum . 7.5 
 
 Palladium 2.5 
 
 Silver ! 2.0 
 
 Total 100.0 
 
 Melting Point 2075° F., 1135° C. 
 
 This alloy is equivalent in hardness to ordinary 22-K. gold, 
 containing 91.6 per cent, gold, 3.5 to 4 per cent, copper and 4.5 
 to 5 per cent, silver. Now, as the copper is the active hardening 
 agent in the 22-K. gold and as we know from the preceding data 
 that platinum and palladium exert somewhat less than half of the 
 hardening influence of copper, it will be seen that the total of 10 
 parts platinum and palladium are about equal in hardening power 
 to the 3.5 to 4 parts of copper usually present in 22-K. gold; and thus 
 we get an alloy equivalent in hardness to the ordinary 22-K. plate. 
 
 The silver content, 2 parts, is no factor whatever, except as a 
 color-modifying agent, because it is an object to adhere to a certain 
 standard of color throughout the whole series of alloys. As there 
 is no copper whatever present in this alloy, it is absolutely non- 
 oxidizable, but the great advantage that an alloy of this character 
 possesses over an ordinary 22-K. plate is the fact that its melting 
 point is much above that of ordinary 22-K. gold, approximately 
 225° F to 250° F. higher, and instead of sweating a band and floor, 
 it may be very easily soldered with pure gold or 22-K. plate and 
 resoldered with the same or lower-grade plate gold innumerable 
 times, without any danger of burning or blistering. 
 
 Any, or all, of the alloys in the series following plate No. 2, may 
 be safely used as solders on plate No. 1, thus permitting many sol- 
 dering operations without danger of burning the gold, as may occur 
 in sweating, or the danger of the solder (if poor quality) burning 
 
A NEW SERIES OF ALLOYS 373 
 
 iuti) and alloyiiiii witli tlu' ^old, as often occurs when iisin*;' the 
 so-called " easy-fiowiug" solders. It is t>\ident, therefore, that 
 this alloy oii'ers a fjreat many advantajies o\er the ordinary 22-K. 
 plate jiold. 
 
 Gold Plate No. 2. — As has been impressed by Dr. Peeso, it is 
 al)solutely essential to use for removable bridge-work, a hard, 
 durable gold, such as U. S. coin gold. It may be well, at this time, 
 to state that U. S. coin gold contains 90 per cent, pure gold and 10 
 per cent, copper, whereas the so-called coin gold obtainable from 
 most supply houses contains, as a rule, some silver, which softens 
 it and makes it work more easily, it therefore does not possess the 
 strength and durability required. 
 
 The following formula replaces coin gold most satisfactorily: 
 
 FORMULA OF GOLD PLATE No. 2. 
 
 Per cent. 
 
 Gold 84.5 
 
 Platinum 8.. 5 
 
 Palladium 2.0 
 
 Silver 0.5 
 
 Copper 4.5 
 
 Total 100.0 
 
 Melting Point 1975° F., 1080° C. 
 
 In this formula, in order to obtain the equivalent hardness of 
 coin gold, it is necessary to use copper. We can again readily see 
 just how the hardening properties of the alloying elements are 
 utilized. We have 4.5 per cent, copper, and the platinum and 
 palladium replace the rest of the copper, thus giving us an alloy 
 equal to V. S. coin gold. This oxidizes, of course, to a slight extent, 
 but the oxidation is not objectionable, and this alloy can be used 
 to replace coin gold i)ractically for every purpose, and may be 
 .soldered with other alloys in the series which have the same color. 
 When soldered with casting gold, B or (", the attachment of the 
 floor to a })and cannot open up during the final soldering unless 
 fleliberately abused, because the soldered junctions are actually 
 higher in melting point than ordinary gold plate. 
 
 The fusing point of this alloy is approximately 225° F. higher 
 than coin gold, an<l it possesses all the advantages over coin that 
 the No. 1 formula has over 22-K. gold, 
 
 'i'hesc allo\'s, Xos. I and 2, can be utilized to great advantage 
 in the con.struction of swaged plates, both full and |)artial, especially 
 where it is desired to make the |)lates (»f two or three thin hiNcrs, 
 (Ml account r)f the high melting |)oint (»f the alloys, which permits 
 
874 DENTAL METALLUBGY 
 
 of thorough soldering of the lamina? without danger of burning. 
 When used in conjunction with the other alloys in the series, these 
 golds enable the operator to produce dentures far superior to those 
 made from the golds ordinarily employed, on account of increased 
 strength, minimized bulk, and perfect color harmony, throughout 
 the whole structure. 
 
 It should be borne in mind that high fusing golds, such as these, 
 cannot be "sweated" advantageously. This is a characteristic of 
 all gold alloys high in platinum metals. 
 
 Alloys for Prosthetic Castings. — As has been previously stated, in 
 order to cast sections of bridge-work, saddles, partial plates, etc., it 
 is essential to have alloys that are rigid in the cast form, to obviate 
 the necessity for increased bulk. Again, the value of the hardening 
 properties of the alloying elements becomes apparent, as in the 
 following : 
 
 FORMULA OF CASTING GOLD "B." 
 
 Per cent. 
 
 Gold 80.0 
 
 Platinum 9.5 
 
 Palladium 2.5 
 
 Silver 1.0 
 
 Copper 7.0 
 
 Total . . 100.0 
 
 Melti?jg Poin-t 1975° F., 1080° C. 
 
 We have here 7 per cent, copper and a total of 12 per cent, of 
 the platinum metals, which makes an alloy considerably harder 
 than coin gold. When cast, this alloy is about midway in hardness 
 between rolled coin gold and clasp metal. The melting point of 
 this alloy is about 50° F. below pure gold. It is intended for use 
 with the nitrous oxide blow-pipe and should be melted with same, 
 if a considerable quantity of gold is to be cast. Sufficient quantities 
 for small castings can be melted with the ordinary blow-pipe. 
 The copper content being comparatively low permits of the use 
 of the nitrous-oxide blow-pipe without any material change or 
 deterioration of the alloy, if a suitable reducing flux is used in 
 connection with it. 
 
 This alloy corresponds in color with plate No. 1 or No. 2, and may 
 be used to cast cusps or cusps and contours directly to bands of 
 either plate No. 1 or plate No. 2. It makes a particularly suitable 
 gold for cast occlusal surfaces on account of its hardness and dur- 
 ability. 
 
 The next formula is a modification of "B" and brings out an 
 
A NEW SERIES oP ALLOYS 37o 
 
 interesting point in connection with the effect of copper and the 
 phitiiunn metals on the decrease and increase of melting points. 
 
 FORMULA OF CASTING GOLD "C." 
 
 Per cent. 
 
 Gold 80.5 
 
 Platinum q 5 
 
 Palladium 2.0 
 
 Silver 2.0 
 
 Gopper •. . . 9.0 
 
 Total . . 100. 1) 
 
 Meltin-j; Point 1S00° F., 980° C. 
 
 We note in this formula an increase of two parts of copper 
 and a decrease of a total of 3.5 parts platinum and palladium, 
 the consequence being that the melting point is dropped by the 
 increase of copper and by the decrease of the platinum metals. 
 The melting point is dropped about 100° F. and brought down to 
 approximately that of 22-K. gold. This lowering of the melting 
 point permits this alloy to be melted readily for large or small casting 
 with an efficient illuminating gas and air blow-pipe. It is identical 
 in strength, hardness, color, etc., with casting gold "B" except the 
 fusing point and resistance to the nitrous oxide blow-pipe flame. 
 If the latter is used, caution must be taken to use a reducing flux 
 and not superheat the metal. This applies to coin gold, too, if 
 same is cast. Excessive heat, if aijplied with the nitrous^ oxide 
 blow-pipe, atid lack of a suitable redttciiu/ flux, icill permit the 
 oxidation of considerable copper and the dissemination of oxide 
 throughout the casting. 
 
 Gold for Inlay Casting. — Since the introduction of the casting 
 process, pure gold has l)een generally advocated for cast fillings, 
 etc., on account of its suppo.sed minimum shrinkage, softness and 
 malleability, and consequent ease with which the margins could 
 be burnished to eliminate the cement line of an inlay. 
 
 -V good many operators have failed to cast pure gold satis- 
 factorily and claim that they can cast inlays with scrap gold and 
 produce better and sharper margins. To those who have not 
 experienced this difficulty, it may appear very strange, but, never- 
 theless, it is a fact that alloyed gold, when ])r()perly alloyed, and 
 under fair-casting conditions, invariably casts with sharp, true 
 margins, whereas pure gold has very often failed to accomplish the 
 |)ur|)ose, both at the hands of the author and many others. 
 
 It may lie well to consider that the casting of scrap gold of indcfi- 
 
376 DENTAL METALLURGY 
 
 nite composition is rather a hazardous and usually unsatisfactory 
 procedure and a great many operators recognizing that fact, are 
 using 22-K. gold, coin gold, etc., with better results than they 
 have been able to obtain with pure gold. 
 
 It is a well-known fact that pure platinum, pure palladium and 
 pure silver absorb hydrogen, oxygen and other gases, while in the 
 molten state, and retain some of the gases upon solidification. It 
 is not generally known, but nevertheless true, that pure gold absorbs 
 nitrogen, hydrogen and oxygen, and retains a considerable per- 
 centage of one or more of the absorbed gases upon solidification.^ 
 This tendency, on the part of the metals mentioned, to absorb 
 gases, is minimized and sometimes entirely eliminated by alloying 
 and a small percentage of copper, palladium or platinum will mater- 
 ially alter the behavior of pure gold upon solidification. Castings 
 made with a slightly-alloyed, pure gold, will be found to possess 
 sharp margins and practically equal pure gold in color, ductility, and 
 facility of burnishing, and to be comparatively free from cavities 
 or blow-holes, such as are often found in unalloyed gold castings. 
 
 A number of cases under observation have shown that fillings 
 of slightly-alloyed gold do not, after a period of wear, present the 
 same pitted surface so characteristic of cast pure gold fillings 
 under the same conditions. 
 
 The rounding of the margins in cast pure gold fillings is usually 
 accompanied by a separation of the residue button from the casting 
 which takes place just prior to the completion of solidification. This 
 occurs particularly when a comparatively large sprue is used, and 
 more especially when a large residue button is used at the same 
 time. An explanation of this occurrence may reasonably be 
 attributed to the following: If the sprue is quite large, and the gold 
 residue button large, the residue remains fluid for a considerable 
 period of time after the casting pressure has been applied, and there 
 appears to be a tendency for the large button to draw to it the gold 
 of the casting through the medium of the large gate (the sprue). 
 A large button of gold very often draws only part of the sprue to 
 it, thus separating the connection between the residue button 
 and the casting, and arresting the exercise of the casting pressure 
 which would otherwise be transmitted from the button to the 
 sprue and then to the casting proper. For those who wish to use 
 pure gold for casting, it is suggested that the quantity of gold used 
 
 1 Roberts- Austen, Introduction to the Study of Metallurgy. 
 
A NEW SERIES OF ALLOYS 377 
 
 in the casting operation should not exceed more than three pi-nny- 
 weights above the amount actually required for the casting proi)er, 
 and also that the sprue l)e no larger than 1() gauge B. and S. This 
 will serve to lessen the area of connection between the casting and 
 residue button, so that this area (the sprue) may solidify more 
 rapidly, and in conjunction with the smaller button, which naturally 
 freezes more rapidly, tend to prevent the separation pre^-iously 
 discussed. 
 
 Another point that is well to consider, is the fact that alloying 
 of gold reduces the surface tension and cohesion of the molecules 
 while in a molten state, and increases the fluidity, thus facilitating 
 the flow of the metal, requiring less pressure to force the gold into 
 the mould, and consequently, lessening the danger of distorting the 
 mmild. (See investment compounds for casting.) 
 
 FORMULA OF CASTINCi GOLD "A." 
 
 Per cent. 
 
 Gold 97.0 
 
 Platinum 1 . .'> 
 
 Palladium 0.;5 
 
 Silver 0..i 
 
 Copper 0.9 
 
 Total 100.0 
 
 Meltin-g Point 194.5° F., 106.3° C. 
 
 This alloy makes an efficient substitute for pure gold, as the 
 comparatively small amount of alloy does not harden the gold 
 sufficiently to prevent burnishing, nor does it affect the color 
 perceptibly. Copper is the most suitable agent for increasing the 
 fluidity, and the small percentage used does not materially harden 
 the gold. The drop in melting point is compensated for by the 
 platinum, and the small percentage of silver counteracts the color- 
 ing effect of the copper on the gold, the consequent alloy possessing 
 practically the same melting point as pure gold, and producing, 
 almost invariably, sound castings, withont the special precaution 
 which must be taken when pure gold is used. 
 
 This alloy will be found suitable for use in teeth close to others, 
 with fillings or inlays made of pure gold, in order to maintain color 
 harmony. 
 
 As all the alloys in the series, excepting the casting gold A and 
 the elastic alloy described later, are practically of a uniform colorand 
 somewhat lighter (grayish red) and less cons|)i('uo\is than pure gold 
 or coin gold, it has been found advisable to also formulate an alloy 
 for casting inlays to harinoni'/e in color with the rest of th<- series. 
 
S?8 DENTAL METALLURGY 
 
 FORMULA FOR CASTING GOLD "D." 
 
 Per cent 
 
 Gold . ■ '....'.. 95.0 
 
 Palladium 3.3 
 
 Silver 0.4 
 
 Copper 1.3 
 
 Total 100.0 
 
 Melting Point 1945° F., 1063° C. 
 
 In this alloy, the palladium decolorizes the pure gold, and raises 
 the melting point. The copper brings it back to the pure gold 
 standard, and by the addition of the small percentage of silver to 
 counteract the reddening effect of the copper, a color effect is 
 obtained in perfect harmony with the rest of the series. 
 
 This gold is quite soft and malleable and may be burnished with 
 practically the same facility as pure gold. This question of bur- 
 nishing margins of inlays is rather a more or less indefinite procedure. 
 It is the author's opinion that very little effective burnishing 
 (spinning) can be done on inlay margins, and that only after the 
 margins are stoned down to an extremely thin edge. Experience 
 has shown that it is advisable to use hard and durable alloys for 
 inlays, especially those intended to aid in supporting bridge-work, 
 and then only when supplemented with posts or dowels. 
 
 This alloy, D, can be combined with B or C, to obtain harder 
 alloys, with no difficulty and no change in color, thus enabling the 
 operator to obtain practically any degree of hardness for special 
 requirements in inlay casting. 
 
 CLASP METALS. 
 
 As previously stated, the alloys known as clasp metal, or plat- 
 inized gold, as ordinarily obtainable, have been used, with poor 
 results, for casting sections of bridge-work, etc., and are being 
 used to a large extent, and with but mediocre results, as a substi- 
 tute for iridio-platinum for crown posts, dowels, etc. The ordinary 
 clasp metal is also used to a considerable extent for posts or dowels 
 in the construction of cast base crowns, with usually poor results, 
 on account of its brittleness, especially after it has been cast 
 against. There appear to be about four distinct types of clasp 
 metal obtainable at the supply houses. 
 
 The following formulae are nearly exact and type one and two 
 readily indicate the particular role that copper plays as a hardening 
 agent : 
 
CLASP METALS I'.TO 
 
 TABLE III.— COMPOSITION OF CLASP METALS. 
 
 CoNSTiTUKNT Metals. Type].* Type 2.* Type 3.* Type 4.** ' Elastic gold. 
 
 Gold 63 65 63 6.5 64.0 
 
 Siilver 1-t 15 17 6 1.5 
 
 Copper .... 21 13 7 7 7.0 
 
 Platinum .... 2 7 13 18 11.0 
 
 Palladium ... 4 16.5 
 
 Comparative 1600° F. 1725° F. 1S60° F. 1960° F. 2100° F. 
 
 Melting Point 870° C. 940° C. 1015° C. 1070° C. lI.-)0° C. 
 
 * From analysi.-;. ** Is known commercially a.s "high fusing" clasp metal. 
 
 Type 1 represents a class of clasp metals of which there are 
 several on the market. They contain a trace of platinum, so that 
 they may legally he called platinized gold, and a very high per- 
 centage of copper. The copper content confers a high degree of 
 hardness and elasticity upon the alloy, but during subsequent 
 heating (soldering and annealing) and working, the alloy softens 
 considerably and loses a good deal of the original elasticity, and 
 sometimes becomes very brittle, especially when over-heated.^ 
 As the melting point is quite low, soldering with even a compara- 
 tively low fusing solder is apt to endanger the integrity of the 
 alloy more often than not. 
 
 Type 2 represents a class of clasp metals which contain a larger 
 percentage of platinum and less copper. This alloy, while not quite 
 as elastic before annealing, retains its elasticity after annealing or 
 soldering, better than type one, and makes a quite satisfactory 
 material for clasps for vulcanite work, etc., if not excessively heated 
 and otherwise abused. 
 
 Neither of the two alloys are suitable for work recjuiring repeated 
 .soldering operations. Posts or dowels made of these alloys and 
 ca.st again.st, usually .show a partial fusion and although this fusion 
 is not always evident, the i)osts if cast against break away (at the 
 junction) ultimately. These alloys are ab.sohitely unfit for the 
 making of split jiins. 
 
 'JVpe '.] ofl'ers a nnich better material. It contains still less 
 copper, and more platinum, but has not sufficient strength and elas- 
 ticity. For want of a better material, it has been used for the 
 
 • CJold-«ilver-coi)per alloy.s containing over 15 per ((^nl. foppifr an; <|iiilc luillie, 
 very unnnirorrn, and variahjc in licli.-tvior upon nitittr.iWue,. 
 
380 ■ DENTAL METALLURGY 
 
 construction of split pins for a number of years. In addition, the 
 fusing point, although higher than that of types one and two, is too 
 low, and when attempting to solder the solid portion of a split pin 
 with coin gold, the metal is apt to fuse partly, becoming granular 
 and brittle, and the finished pin is apt to give out in use. The type 
 three clasp metal has been cast against with fair results, but the 
 danger of burning it is imminent. 
 
 In the three types of clasp metals under discussion is demon- 
 strated the value of copper, and its superiority over platinum as a 
 hardening agent, and the value of platinum, in raising the melting 
 point lowered by the copper. 
 
 A number of experiments were made to improve the type three 
 clasp metal, and it can readily be seen from formula of type four, 
 how comparatively simple it was to do so, having established the 
 properties of the binary alloys as a foundation. By raising the 
 platinum to 18 points, the melting point and the elasticity were 
 increased somewhat. Even at this stage, the advance in melting 
 point appeared insufficient, and, as it was deemed advisable to avoid 
 more platinum on account of the danger of its not alloying uniformly, 
 palladium which alloys readily was added, and the melting point 
 increased to a total of app. 100° F. above type three. No more 
 palladium was used on account of its decolorizing action. With 
 the comparatively small content (4 per cent.), the color of the 
 alloy is still quite gold-like. This alloy has been used with uni- 
 formly good results. It may be soldered safely with coin gold (for 
 split pins) , and may be cast against safely if a comparatively heavy 
 gauge of wire (above 10 g. B & S) is used. 
 
 In view of the fact that for split pins, dowels for cast base 
 crowns, etc., color is no object, it was deemed advisable to raise the 
 melting point even above that of type four and the elastic gold 
 was formulated, using a considerable percentage of palladium. 
 The palladium, of course, decolorized the alloy completely, but 
 raised the melting point very considerably, and, in conjunction with 
 the copper and the considerable percentage of platinum, produced 
 an elasticity even beyond that of type four, and a melting point 
 very considerably higher. 
 
 This alloy can be soldered with perfect safety with pure gold 
 or anything below that in melting point. It may be cast against 
 with perfect safety (except very thin wire) , and retains its strength 
 and elasticity after any reasonable number of soldering operations 
 that it may necessarily be subjected to. It may he soldered very 
 
GOLD SOLDERS 381 
 
 readili/ and iclfli hdtvr union than iridio-platininu. It /.v nincli more 
 rigid than ordinary iridio-platinuin, and possesses elasticiti/ that is 
 practically absent in all of the iridio-platinum alloys and it may 
 therefore replace the latter and ordinary clasp metal for a great many 
 purposes. 
 
 In the makino; of split posts of the elastic gold, it is advisable to 
 solder the area that is intended should remain solid with coin gold, 
 as it oilers a strong color contrast to the comparatively white elastic 
 gold. 
 
 The line of demarkation between the solid and the split portions 
 of the post, will be then readily distinguished. As the coin gold is 
 of sufficiently high melting point, it will not refllow during later sol- 
 dering operations. 
 
 The comparative hardness and the elasticity of the four types of 
 clasp metals and the "elastic" gold is approximately as illustrated 
 in the following : 
 
 COMPARATIVE ELASTICITY AFTER ROLLING AND 
 ANNEALING ONCE. 
 
 Type 1. Type 2. Type 3. Type 4. " Elastic" Gold. 
 
 10 9 8 9+ 10 + 
 
 COMPARATIVE LOSS OF ELASTICITY AFTER SOLDERING AND 
 ANNEALING THREE TIMES. 
 
 Type L 
 
 Type 2. 
 
 Type S. 
 
 Type 4. 
 
 "Elastic" Gold. 
 
 2-.3 
 
 1-2 
 
 1 + 
 
 1 
 
 .5-1 
 
 Types one and two become very brittle if overheated during 
 soldering. Type three is subject to same to a lesser degree and type 
 four only occasionally. The "elastic" gold appears practically 
 immune to temperatures below the melting point of pure gold. 
 
 r|as|) metal should always be annealed before use, as maiuifac- 
 turers often neglect to do so after the rolling or drawing operations. 
 
 GOLD SOLDERS. 
 
 In order to obtain the (Icsiriibic \niiformity of color in a denture 
 without silbsecpient gold "washing," Jis adx'oeated by some, it 
 was necessary to formulate solders to correspond in color with the 
 other alloys. Incidentallx', it is well to consider- the imposition that 
 has been practiced n|)on the |)rofcssion by some of the imscnipnions 
 manufacturers of gold solders. 
 
382 ' DENTAL METALLURGY 
 
 For many years, a great many in the profession have been under 
 the impression that gold solders stamped 18-K. were actually 18-K, 
 (75 per cent, gold) in fineness. This was not so and a number of 
 the manufacturers were producing, and are still producing, solders 
 marked 18-K., etc., anywhere from two to six karats below the 
 mark. In addition, the solders mentioned are not only deficient 
 in gold content, but contain many deleterious alloying elements, 
 such as high percentages of cadmium, iron, etc., in order to complete 
 the required total content of base metals in the solders. 
 
 On the other hand, the reputable manufacturers have consis- 
 tently stated that their solders were approximately two karats 
 below the mark, and intended for use on that karat of plate. The 
 reputable manufacturers have recently started to stamp the actual 
 fineness on their solders and the others have followed suit; but 
 some manufacturers still persist in the practice of misrepresentation 
 by not actually furnishing the gold content indicated by the fine- 
 ness stamp on the product. 
 
 Alloys of Gold with Metals in Group 3. — Besides zinc, the other 
 three metals in Group 3, namely, cadmium, tin and aluminum, are 
 being used to a very large extent as alloying elements in making 
 gold solders. Cadmium, if used in large percentages, debases the 
 alloy very considerably and renders it practically unfit for use in 
 the mouth. 
 
 Tin is also used to a considerable extent, as it lowers the melting 
 point of gold very considerably, but it renders the gold quite 
 brittle and aids materially in the tendency of solder to burn into 
 the work, which property is characteristic of all the so-called easy 
 flowing solders. The term "easy-flowing" is undoubtedly a mis- 
 nomer. Rather, these solders melt "easy," but do not flow "easily." 
 They ball up and stick, and if the heat is forced to induce flow, they 
 burn into the work with consequences too well known to require 
 further discussion. 
 
 The value of aluminum, as a constituent of gold solders, is yet 
 to be proved. It is a constituent of most of the patent commercial 
 alloys used by jewelers in compounding their solders. 
 
 Solders made according to the following formulae will be found 
 satisfactory in color, strength, and fusing point, although higher 
 in fusing point than the so-called easy-flowing solders, for which 
 there seems to be a "popular" demand. They will be found to 
 flow readily if the work on which they are to be used is brought up 
 to the proper temperature. 
 
COMPOVNDIXG OF GOLD ALLOYS 383 
 
 FORMULAS FOR GOLD SOLDERS. 
 
 SOLDER No. S4. 
 
 Per cent. 
 
 Gold 84.0 
 
 Copper 7.5 
 
 Silver 5.5 
 
 Zinc . 3.0 
 
 M. P. lOM" F., 000° C. (20-Karat fine). 
 
 SOLDER Xo. 7(). 
 
 Gold ... 70.0 
 
 Copper 11.5 
 
 Silver 8.5 
 
 Zinc 4.0 
 
 M. P. 1550° F., 840° C. (IS-Karat fine). 
 
 SOLDER No. 08. 
 
 Gold 68.0 
 
 ( 'i )pper 4.5 
 
 Silver 12.5 
 
 Zinc 5.0 
 
 M. P. 14.50° F., 785° C. (16^-Karat fine). 
 
 Tlie first and second, (S4 and 7(), will be found sufficiently low 
 in incltint; point for all ordinary operations where Dr. Peeso recom- 
 mends the use of his No. 21 and No. 19 solder. The number (38 
 solder, although higher in actual gold content than the best so-called 
 18-K. solder obtainable, is still too low a grade to be used in general 
 work, especially in fixed l)ridge-work, but may be used in connection 
 with rcmo\able bridge-work or plate work because in that work or 
 repah- work there is rccpiircd at times a lower-fusing solder. 
 
 COMPOUNDING OF GOLD ALLOYS. 
 
 Althongh the new series of alloys, made with practically no 
 deviation from the formula* which are given herein, may be ]nir- 
 cha.sed from the supply houses, the author considers it well to give 
 a mimbcr of directions to those who may desire to compound the 
 various alloys. 
 
 It is not |)ractical to make a small (piantit^', es|)ccially if for plate 
 gold or solder which is to be poured into an ingot mould and rolled. 
 The higher the melting point of the alloy, the more necessary it is 
 to have a comparatively large (piantity, an<l it is well not to attempt 
 less than five ounces for plate gold and three ounces for solder. 
 The ela.sti<' alloy should be made in even larger (piantity as it freezes 
 very raj)idly. 
 
384 DENTAL METALLURGY 
 
 It is practically impossible to alloy platinum or palladium with 
 gold in the small blast furnace which the practitioner is likely to 
 have in his laboratory. For all alloys with platinum metals (made 
 on the small scale previously mentioned) it is well to alloy the 
 gold and the platinum metals (rolled very thin), first on a charcoal 
 block, using the nitrous oxide and illuminating gas blow-pipe, or 
 preferably the oxygen and illuminating gas blow-pipe. A number 
 of the alloyed nuggets can then be placed in a crucible on top of 
 the required silver and copper content, covered with a suitable 
 reducing flux and melted, poured into an ingot mould and rolled 
 or drawn. 
 
 When copper is to be used, it is essential that same be chemically 
 pure and especial precaution must be exercised to prevent oxidation 
 as far as possible, which latter can be accomplished by the use of 
 a strong reducing flux. (See under Fluxes.) 
 
 A slight excess of copper should always be added to allow for 
 some loss which invariably occurs. 
 
 If the alloy that it is intended to make is to be used for casting 
 purposes, the procedure is the same as previously described, except- 
 ing that the metal, when properly molten, can be poured into a 
 pail of water and thus granulated. This procedure saves the labor 
 of rolling the ingot and the granulated form of gold is as convenient 
 to use for casting as any other. 
 
 In all cases, just before pouring the contents, the crucible should 
 be well shaken to insure a thorough admixture of the metals. 
 
 Some writers advocate the preparation of alloys for casting 
 in the following manner: Melt the gold, feed the platinum (very 
 thin) into the molten gold and then add copper, etc. It is impos- 
 sible to make a uniform alloy in this manner, especially if copper is 
 used, because a considerable amount of the copper is oxidized on 
 account of direct contact with the blow-pipe flame. In the author's 
 hands the directions previously given have been found to work out 
 admirably. 
 
 In compounding solders where zinc and copper are the con- 
 stituents it has been advocated that brass which contains copper 
 and zinc be used in order to prevent the loss of zinc through oxida- 
 tion and volatilization. This is a very dangerous practice, and 
 the results are very unsatisfactory because it is impossible to 
 obtain a commercial brass that does not contain a considerable 
 percentage of lead, tin, and traces of antimony, etc., which are all 
 very harmful substances and invariably tend to make the solder 
 
REFRACTORY MATERIALS ;}85 
 
 brittle. It is therefore necessary to first make an alloy of chemi- 
 cally jjure zinc and chemically pure copper in a proportion of say 
 one part zinc and two parts copper. This alloy, when properly 
 melted, is granulated by pouring into water, and then, if carefull\- 
 gathered, dried and weighed, the loss of zinc can be determined. 
 The necessary additional copper to make the required alloy is then 
 calculated and added w^hen compounding the solder. 
 
 It is well, of course, to make a considerable quantity of the copper 
 zinc alloy, as the cost is slight and the prepared alloy is then avail- 
 able when wanted. It has been stated that zinc volatilizes very 
 readily from solders. This is quite contrary to the author's findings. 
 The small percentage of zinc as given in the formulae herein is 
 quite stable after remelting several times. The authors who claim 
 this strong volatilization of zinc may have been dealing with a 
 solder of unknown constitution in which they suspected zinc but 
 which probably contained a percentage of cadmium which vola- 
 tilizes quite readily. 
 
 REFRACTORY MATERIALS. INVESTMENT COMPOUNDS 
 FOR SOLDERING. 
 
 The normal contraction of gold from the molten to solid state is 
 approximately 2 per cent. The contraction of gold solder is prac- 
 ticall>' the same, although some of the constituents have a higher 
 contraction than gold, but when combined in an alloy the movement 
 is practically the same. 
 
 While possibly there may be a slight difference between the 
 contraction of solder and gold, a considerable contraction occurs 
 nevertheless, and is the cause of a great deal of trouble. 
 
 A number of soldering investment compounds on the market arc 
 claimed b>' the manufacturers to possess neither expathsioii nor 
 contraction, and therefore perfect. Granting, for the sake of the 
 argument, that such is the case, we still have the contraction of 
 solder to contend with, antl how arc we to produce a soldered 
 bridge or denture that will fit and go into place accurately, when a 
 mimber df the units in the work have been drawn together by the' 
 roiitra<tion of the solder '! 
 
 rnfortiniatcly, we have not merely the contraction of the solder 
 
 to contend with, but we have a niiicli i -c prolific cause of disaster. 
 
 For example, we have a number of completed sections, such as 
 castings, to join together where but a very small (piantity of solder 
 2.5 
 
586 
 
 DENTAL METALLURGY 
 
 is to be used, and yet, after soldering, we find that the finished piece 
 is contracted and distorted and will not go into position. The fact 
 of the matter is that practically all the commercial compounds 
 shrink upon heating, when brought up to the proper temperature 
 for soldering. 
 
 In some commercial investment compounds the shrinkage is 
 extremely high, fully 6 or 7 per cent., so it is evident that the 
 principal cause of the trouble lies not so much in the actual contraction 
 of the solder, as it does in the great contraction of the average invest- 
 ment, even before the case is quite hot enough to apply the solder. 
 
 Fig. 652 
 
 Fig. 652 shows an ordinary simple bridge assembled and ready 
 for investment. The porcelain facings are spaced as per instruc- 
 tions from time immemorial. Fig. 653 shows the case invested 
 and the distinct spacing of the backings. 
 
 The case is then heated, and if an examination of the investment 
 is made with a magnifying glass, just before placing it on the sol- 
 
 FiG. 653 
 
 dering block, it will be noticed that the units have beeri drawn 
 together, as in Fig. 654, and when the case is soldered and cooled, 
 the facings are very apt to be checked, on account of having been 
 brought together into very strong contact. 
 
REFRACTOR Y MA TERIA LS 
 
 387 
 
 When attempting- to place l)ack on the cast, difficulty is encoun- 
 tered, but as the })laster yields, the bridge is forced down and then 
 becomes evident the loss of the contact points, as illustrated in 
 Fig. (555. 
 
 Fig. 654 
 
 This discrepancy will not be considered by some operators as a 
 serious factor. In fact those who solder directly on the cast destroy 
 the evidence for the time being. If it is a fixed bridge, it is forced 
 home some way or other and let go at that, but on theother hand, 
 if a removable bridge, even as small in dimension as the one illus- 
 trated, it is practically impossible to place it in position, and the 
 matter is a most serious one, as a good many operators have found. 
 
 Fig. 655 
 
 Some writers advocate com])leting the dummies and then placing 
 them in perfect contact to prevent the shrinkage of the solder used 
 to unite the sections. This is practically impossible, because the 
 metallic units arc infinitely stronger than the investment, and 
 expanding imder lu-at will invariably split the investment (see Fig. 
 ()50) and thus often cause a serious distortion in the soldered piece. 
 
 There seems to have been, as a search of the literature has shown, 
 al)solutely no consideration given to the movement of the refractory 
 mass that holds the parts /// .vV// during llic |)nliiiiinary heating 
 and final soldering operations. 
 
388 DENTAL METALLURGY 
 
 The author's aim in experimenting has been not merely to pro- 
 duce an investment compound that would merely not shrink, but 
 one that would actually expand, move in unison with the solid 
 invested metal and spread the units sufficiently so that when a 
 reasonable amount of solder is flowed to connect the units, the 
 contraction of the total piece woidd he neutralized by the expansion 
 of the investiment. 
 
 Fig. 656 
 
 Before attempting to formulate an investment compound pos- 
 sessing such properties, it is necessary to consider the chemical and 
 physical properties of refractory materials that may be employed 
 in the compounding of investment materials. 
 
 In one of the most " popular" books on crown and bridge- work,^ 
 the following appears: 
 
 "Many substances may be used in combination with plaster of 
 Paris, which is necessarily the basis because imparting the property 
 of crystallization, and which must be incorporated to the extent of 
 at least 50 per cent. 
 
 " The remaining proportion may be then composed of such 
 materials as will, by virtue of their characteristics and physical 
 properties, meet such requirements. The following are serviceable: 
 
 Powdered silex, Pulverized pipe clay, 
 
 Fine asbestos, Powdered fire brick. 
 
 Beach sand. Magnesium oxide. 
 
 Marble dust, Pumice stone. 
 
 "A combination of any of these ingredients in varying propor- 
 tions with the proper quantity of plaster will usually possess the 
 necessary qualities, etc." 
 
 Before even considering a compound of expanding properties, it 
 is well to thoroughly understand the properties of plaster of Paris 
 
 1 Goslee's Priticiplcs and Practice of Crown and Bridge-work, pp. 36-.37. 
 
REFRACTORY MATERIALS 389 
 
 and the other materials enumerated in tlie list of suitable refrac- 
 tories, in order to see if it is possible to even produce an investment 
 comi)ound that will at least not .shrinlc under heat. 
 
 Plaster of Paris.— Plaster of Paris, CaS04 (calcium sulphate) 
 is made by burning gypsum rock. In the process of burning, most 
 of the water is dri\en ofl". The phenomena of recombining with 
 water and crystallizing is well kno\Mi and need not be discussed 
 here. It is universally used as the binder for all investment com- 
 pounds used both for soldering and casting. It shrijiks very 
 considerably upon heating, but for want of a better material must 
 be employed. 
 
 The more plaster used in an investment compound, the harder 
 the resultant mass will be, and the iiiore s-hrinkage w^ll take place. 
 As will be shown subsequently, any such proportion as the oi) per 
 cent, mentioned by the author quoted is absolutely out oj question 
 because it has been found, so far, impossible to compensate for the 
 contraction of the binder, by the addition of any other material, 
 even if possessing the property of expansion. 
 
 Powdered Silex. — Silex is the commercial term applied to silicon 
 dioxide (SiO-.j which is the main constituent of rocks, stones, clays 
 and many other minerals. A great deal of it is also found in a free 
 state and in the form of quartz, rock crystal, flint, opal, chalcedony, 
 etc. The so-called silex is often practically pure Si02. However, 
 different ^■a^ieties of silicon dioxide exist, and although all of a similar 
 chemical composition, they possess varying physical properties. 
 
 Silica obtained from quartz or rock crystal, consists of sharp 
 crystalline particles and possesses a high specific gravity, 2.0 to 2.8. 
 It expands considerably upon heating, but loses this property grad- 
 ually upon reheating frequently or fusing completely.^ The melting 
 point of pure silica is approximately 3200° F. 
 
 Another variety of silica that exists quite as frequently as the 
 crystalline, is an amorphous form which j)ossesses a lower specific 
 gravity, 2.2 to 2.4. It has very little expansion upon heating, and 
 some varieties of the same type do not expand at all. 
 
 Still a third variety exists in a tabular form and is extremely 
 light and porous. It is known as diatomaceous earth or kieselguhr. 
 Its .specific gravity is 1 .(> to I .S. It is mined in v<-r\ great (juantities 
 
 ' Ut«imil« made of fiistjd «ili<-ii art; rcplaciiiK plaliiiuiii ware to a Kroat extent 
 in chcmir-al work. Ah the foeffifient cxpanHion i« very Mniall (().()()0()(J0.'i4 jjcr ° ('.) 
 it i.-i jKiMrtiMe to .tuhjerl »riicihle«. cuhmtoU-h. ctr-.. to rapid cliaiiKCH of tcin))oraturo 
 wiihr.iit danKCT of l.rcakaKc Apparatus «tiital)lc for dental purposes i.s manufac- 
 tiir«"d l»y tlie Tlierriial Syiidi<:ilc F>l<i., of N'cw Vork. 
 
390 
 
 DENTAL METALLURGY 
 
 and used very extensively as a heat-insulating agent, but con- 
 tracts very strongly, and therefore is totally unfit for use as part 
 of a dental refractory compound. 
 
 As stated before, these various forms of silica can be obtained in 
 almost a pure state and are alike chemically, but the term "pow- 
 dered silex," means nothing unless a particular type is specified, 
 and the individual, who is not conversant with the matter, is as 
 likely as not to purchase and use a grade of least expansion. The 
 crystalline variety, of high specific gravity, expands under heat con- 
 siderably, and in this fact lies the solution of the whole problem. 
 
 A mixture of 50 per cent, plaster of Paris and 50 per cent, silica, 
 even if the latter is of the variety possessing the highest expanding 
 properties, contracts very considerably when brought up to the 
 temperature required for soldering or casting operations. 
 
 In order to be brief, the author will state that all the other items 
 in the list of suitable materials have a positive shrinkage, with the 
 exception of beach sand. The objection to the latter, is the fact 
 that it is often quite impure' and the iron and alkalies that form 
 the major portion of the impurities usually act as a flux, and thus 
 lower the melting point. 
 
 It is well to state that magnesium oxide and marble dust, which 
 latter is of course calcium carbonate, are subject to a particularly 
 strong contraction under heat. 
 
 Fig. 657 
 
 Fig. 658 
 
 Fig. 657 illustrates the comparative shrinkage of one of the best 
 commercial compounds obtainable. A considerable space will be 
 noted between the mass of investment and the rim of the metallic 
 ring in which it was placed after mixing, permitted to set, and heated 
 to soldering temperature. 
 
 Fig. 658 (in cross section) shows even more clearly the contrac- 
 tion after heating when a straight edge is placed across the top of 
 the flask. 
 
kEFRACTORY MATERIALS 391 
 
 To summarize the whole proposition, the author will state that 
 in order to produce an iiiM'.stnwnt compound that not only does not 
 shrink, but actually expands sufficiently to follow the movement of a 
 red hot ring, that it is necessary to use a grade of silica as pure as pos- 
 sible and of the highest e.vpansion, which means, of course, a grade 
 of silica from the quartz group, and a grade of plaster of Paris of 
 the least contraction} As previously mentioned, any such proportion 
 as 50 per cent, plaster cannot be used, because the expansion of the 
 best silica, great as it is, is not sufficient to compensate for even the 
 shrinkage of the plaster. Hence, a loicer percentage of plaster, and a 
 higher percentage of silica must he used. 
 
 FORMULA FOR INVESTMENT COMPOUND (SOLDERING). 
 
 Per cent. 
 
 Plaster of Paris (Excelsior Brand No. 3) 33.0 
 
 Silica (Fine) (F. F. F.) 45.0 
 
 Silica (coarser) (M. C.) 22.0 
 
 Total ■. 100.0 
 
 A compound made according to this formula will he found to 
 expand upon heating to soldering temperature, sufficiently to fill a 
 red iiot ring, as in Figs. O't^ and OOO. 
 
 Fig. 6.59 
 
 Fi(i. OGO 
 
 This property of expansion is sufficient to counteract ilie conf ruc- 
 tion of a normal bulk of solder. Furthermore, thi.s expansion is suffi- 
 cient to follow the movement of in rested metailir sectiinis that hare 
 been previously completed. This compound sets promptly and is 
 sufficiently strong to hold the invested parts in situ firmly. It 
 will withstand the action of hoiling water (when washing out the 
 wax) without disintegration. 
 
 ' It in, no doubt, well known that fine plaster contracts more than coarso plaster 
 wh«n Hiihjected Ui heat. Most of tlio coarsi- l)nil<iin>? plasters are rather uniniiforin 
 and do not posw-HH the hindiiiK i)ow(!r of the finer plasters. The Krade seh-ctiMJ i.« 
 quite uniform and not too coarse to (in-vent efricient hindini.': r)f the mass. 
 
392 DENTAL METALLURGY 
 
 Dr. Peeso has long ago demonstrated the great importance of 
 not soldering work directly on the cast. The work should be so 
 assembled that the waxed-up structure may be removed from the 
 cast, which is made of plaster of Paris, or a more durable material, 
 such as "Artificial Stone" (made from the author's formula), and 
 then transferred to the investment compound. After soldering, the 
 work may be placed back on the cast, which is intact, and required 
 corrections can be made by grinding or trimming here and there 
 before the structure is even tried in the mouth. 
 
 Of course the author has made numerous and exhaustive experi- 
 ments to determine the properties and behavior of various refrac- 
 tory materials, and it is important that the grades of silica and 
 plaster specified be used. 
 
 As the reader can deduct from the preceding, the terms silica 
 and plaster of Paris mean very little, because while the different 
 grades of silica are practically alike, chemically they differ very 
 materially physically. To the author's knowledge, it is possible to 
 purchase at least three or four hundred brands of plaster and over 
 a thousand distinct grades of silica with varying percentages of 
 impurities and varying sizes of particles.^ 
 
 There is no intention to claim that this is the last work on the 
 subject. No doubt, other experimenters will succeed in producing 
 as good or even a better compound with other grades of material. 
 
 Investment Compounds for Casting. — The elements of error, 
 caused by the physical behavior of the metallic alloys and the 
 refractory materials utilized in the casting process, are quite 
 analogous to the conditions that exist in the soldering process. 
 Gold, no matter how alloyed, so far as present knowledge of the 
 subject indicates, does contract in the transition from the fluid or 
 plastic state to the solid or frozen state, and an inlay investment 
 compound that possesses the property of expansion will, at least in 
 measure, compensate for the contraction of gold. 
 
 It is not the author's aim her'e to exhaustively discuss casting 
 problems in general. He simply wishes to suggest a formula for 
 what he considers a better investment compound than is purchas- 
 able, and to point out some of the physical phenomena of existing 
 
 1 The materials used by the author were obtained from W. B. Daniels, 252 
 Front Street, New York City, who is a dealer in minerals and chemicals. He 
 will supply the various ingredients for both the soldering and casting compounds 
 in quantities suitable for the requirements of the practitioner. Of course it must 
 be remembered that such comparatively cheap materials are, as a rule, sold by the 
 ton or car load. Hence, Mr. Daniel's willingness to furnish these materials in 
 small quantities at a moderate price deserves commendation. 
 
REFRACTORY MATERIAL.'^ 393 
 
 conditions. Before discussing the t'ornnila it is well to first con- 
 sider some of the conditions that have to be dealt with. We have 
 not only the contraction of gt)ld to contend with, but we also have 
 the contraction of the wax, and that is a most serious factor indeed. 
 The contraction of wax ift nftnally prodnctive of a greater degree of 
 error than the actual contraction of gold. 
 
 This subject has been covered most thoroughly by Dr. C. S. 
 \ an Horn of Bloomsburg, Pa., in his articles in the Dental Cosmos,^ 
 and his conclusions are yet to be contro\'erted. 
 
 The conditions, which he successfully corrects, are the following : 
 After the removal of a ica.v pattern from the month, at body temperature, 
 it contracts considerably upon reaching room temperature and still 
 more when invested with cold water. His method consists of invest- 
 ing the pattern at approximately 110° F., which increase in tem- 
 perature not merely compensates for the contraction of the wax, but 
 also expands the wax to almost completely counteract the shrinkage 
 of the gold. 
 
 In addition, he uses an expanding investment (made from the 
 author's formula), and the total expansion of the wax, coupled with 
 the expansion of the investment, enables Dr. \an Horn to produce 
 the most accurate fitting inlays the author has ever seen. A 
 study of Dr. Van Horn's technic will am])ly repay anyone who is 
 desirous of obtaining better results. 
 
 Dr. James G. Lane,'- of Philadelphia, was among the first to 
 point out the value of silica as an ingredient of inlay investment 
 compounds, on account of its expansion and consequent ability to 
 counteract the contraction of plaster of Paris (the binder). The 
 formula that he used (plaster 25 per cent, and silica 75 per cent.) 
 expands considerably. In addition. Dr. Lane was also among the 
 first to point out the fact that a hot mould was stronger than one 
 that was heated and allowed to cool. 
 
 In the utilization of the casting process, there are a great many 
 important factors to be considered, among them the fusing point 
 of the investment com})ound which constitutes the mould; the relation 
 of this degree of fusibility to the temperature of the mould at the time 
 the molten metal eiders it; the temperature of the nudten metal at the 
 tim£ it enters the mould mid the pressure used to force the fnolfeu 
 metal into the mould. 
 
 ' Dental CoKnioH, 1»11, pp. (id), 172, 110'.). 1912, \y\>. S!)(), '.)7:{. I9H, p. '.tlO. 
 
 ' S<'o piiporH of .J. Ct. LaiH- in Doiital fosinoH juul Dciiliil Dinost, lOlO 1 I. Also 
 M. A. Wiinl in Dfiitui Co.sino.s. These coiilrilmtioiiH arc very iiitorcslifiK ;iii<l llic 
 inoxt v;ilii:il»lc that have appe.-ired piTlriiiiirm to tlie siiliject. 
 
394 DENTAL METALLURGY 
 
 The fusing point of an investment compound, made of plaster 
 of Paris and pure silica, is under 3000° Y. Some of the commercial 
 investment compounds, which are made with impure silica con- 
 taining a considerable percentage of iron and feldspar, which latter 
 contains alkalies such as sodium and potassium, are often consider- 
 ably lower fusing. Consequently, when superheated gold is cast 
 into such a comparatively fusible investment, a partial union is 
 bound to take place, with the consequence that the gold partly 
 unites with the investment, and the resultant casting is quite rough 
 and inaccurate. 
 
 The strong possibility of such a condition as described leads the 
 author to state his opinion on that apparently never-ending con- 
 troversy regarding the casting of gold in a hot or cold flasJ:. This 
 point has been argued time and time again, some operators claiming 
 that they obtain better results by casting into a hot flask, and others 
 maintaining the reverse. In order to discuss the subject intel- 
 ligently, we must also bear in mind the degree of heat that is utilized 
 for melting the metal to prepare for its entrance mto the mould. 
 
 Let us first consider the following: 
 
 Hot or Cold Mould. — Using the iUymiimting gas and compressed 
 air blow-pipe. 
 
 We shall discuss this phase first because the great majority of 
 castings are accomplished by using the ordinary gas and air blow- 
 pipe. The maximum temperature that it is possible to produce 
 with artificial gas and compressed air is approximately 2450° F. 
 The temperature of the investment in the casting ring when red 
 hot is about 1300° F. If this red hot flask is placed on the castiug 
 apparatus and the quantity of gold, say 5 dwts., placed in the cru- 
 cible, it will take about two and a half minute's exposure to an 
 efficient blow-pipe flame, to bring the gold to the proper state of 
 fluidity to enter the mould. In the meantime, the red hot mould 
 (on the casting apparatus) has cooled considerably, and the actual 
 temperature of the cavity in the mould at the time the gold enters 
 it can be safely calculated not to exceed 900° F. Therefore, casting 
 into a "red hot flask," with an ordinary gas and air blow-pipe, is 
 done with the mould not red hot, but at a temperature approxi- 
 mately 900° F. 
 
 In casting into a so-called "cold" flask using the same blow-pipe 
 and quantity of metal, it wiU be found that it takes longer, say 
 four minutes, to bring the metal into a state of fluidity, and although 
 the flask is at room temperature when the process of melting the 
 
REFRACTORY MATERIALS 395 
 
 gold is started, the subjection of the mould to the Hame of the 
 efficient bIow-{)ipe for a period of tq)proxiniately four minutes 
 raises the temperature of the mould to an extent of nearly 7()(J° F, 
 Therefore, when it is attempted to make a casting with the ordinary 
 gas and air blow-pipe in a so-called "cold flask," the temperature 
 of the mould at the time the gold enters it is approximately 7(J(J° F. 
 
 Upon considering both conditions and comparing the tempera- 
 ture of the moulds, namely 900° and 700° F., it will be readily 
 seen that there is comparatively little difference between the two 
 at the actual time that the casting is done, and consequently both 
 the "hot mould" and "cold mould" advocates are right, strange 
 as that may appear, providing of course, that the ordinary gas and 
 air blow-pipe is employed. 
 
 The author's experiments along this line have shown conclusively 
 that it is hardly possible to superheat the gold with an ordinary gas 
 and air blow-pipe or bring the gold to such a temperature that it 
 will unite with the investment at any stage of the procedure and 
 it is the author's firm opinion that in the hands of the careless or 
 inexperienced operator, the ordinary gas and air hlow-jnpe is a posi- 
 tive insurance against superheating the gold, and therefore insures a 
 casting satisfactory-, at least as far as errors consequent to the 
 superheating of gold are concerned. 
 
 Hot or Cold Mould. — Using illuminating gas and nitrous oxide 
 or oxygen hlow-ptpe. 
 
 Here we have a totally different and quite often a dangerous 
 condition to contend with. While the ordinary gas and air blow-pipe 
 is capable of i)roducing temperatures only somewhat beyond 24(M)° 
 F., it is possible to obtain, without difficulty, 3400° to 35!/()° F. 
 from nitrous oxide and illuminating gas and over 4000° F. from pure 
 oxygen and illuminating gas. It may be well at this time to call 
 attention to the fact that the often used term " oxyhydrogen" 
 is incorrect when used in connection with illuminating gas because 
 of the fact that in order to produce an oxyhydrogen flame it is 
 necessary to have both oxygen gas and h\drogen gas, whereas 
 ordinary illuminating gas contains less than half of its volume 
 of hydrogen, and the balance is principally methane (carbon, etc.). 
 
 It is very difficult to avoid superheating gold when applying 
 such extreme temperatures, and extreme cauti(in must be exercised 
 by the oi>erator. 
 
 As a rule, the cold flask is indicated when using extreme temi)era- 
 tures for melting the gold, because the gold melts very rapidly 
 
396 DENTAL METALLURGY 
 
 (15 to 20 seconds), and comparatively little heat is transmitted 
 to the mould. The mould is then comparatively cool, and even if 
 somewhat superheated gold is cast, it is not so apt to unite with the 
 investment as when both the gold and the mould are superheated. 
 
 TJie author has very often made failures of castings, on account 
 of superheating the gold, and he wishes to impress strongly the fact 
 that extreme caution must be exercised in this connection. 
 
 The nitrous oxide or oxygen and gas blow-pipe offers advantages 
 over the ordinary gas and air blow-pipe as a means of producing 
 heat rapidly, but the maximum temperature attainable with the 
 ordinary gas and air blow-pipe acts as a sort of an insurance against 
 superheating, and, in fact, if efficiently used produces satisfactory 
 casting results in all ordinary operations. 
 
 One of the most prolific causes, in fact, probably the greatest 
 cause that is productive of faulty castings, is the excessive pressure 
 used in forcing metal into the mould. The principal reason for this 
 is due to the fact that in the majority of casting apparatus there 
 is no provision for obtaining a definitely measured and indicated 
 amount of force. It takes just so much and no more pressure to 
 force gold into a given mould, and hold it there until solidification 
 begins. Excessive pressure will not, under ordinary conditions, 
 prevent the normal contraction of gold, because the moidd into 
 which the gold is cast yields, and hence will distort in the same propor- 
 tion as excessive pressure is applied. It may be true that a pressure 
 of 2000 pounds per square inch may totally prevent contraction, but 
 where is the mmdd that will stand that pressuref 
 
 It is unfortunate that more operators do not realize the true value 
 of an efficient casting apparatus such as the Taggart, and the false 
 economy resulting from the use of an intrinsically faulty or make- 
 shift device. 
 
 B}^ using a grade of silica of maximum expansion, and a grade of 
 plaster of minimum contraction, it is possible to produce an invest- 
 ment compound as follows: 
 
 FORMULA FOR INVESTMENT (CASTING). 
 
 Parts. 
 
 Plaster (Excelsior Brand No. 3) 29.0 
 
 Silica (Fine) (F. F. W.) 71.0 
 
 Total 100.0 
 
 The plaster is the same as is used in the soldering investment. 
 The silica is similar to the fine grade utilized in the soldering invest- 
 ment formula, but it is purified, and combines with water readily 
 
REFRACTORY MATERIALS 397 
 
 without releasing dirt, scum, etc.,* and consequent bubbles. An 
 investment made from this formula will l)e found to expand slightly 
 more than Dr. Lane's formula, although the plaster of Paris content 
 is higher, and for the same reason somewhat stronger, and more 
 resistant to excessi\e pressure. 
 
 Compounding of Investment Materials. — It is a well-known 
 fact that \ery few commercial in^•estment compounds are uniform 
 in composition. In other words, although the manufacturers claim 
 that their formulae are adhered to, there appear \ariations in 
 batches purchased at different times. This is due to the fact that 
 insufficient attention is paid to testing the different batches of raw 
 material, and also to the faulty compounding due to the large 
 quantities mixed at a time. One commercial preparation has been 
 found, on the contrary, quite uniform, ff)r the simple reason that 
 the manufacturer pays especial attention to the testing of the 
 raw materials and compounds, the mixture in comparatively small 
 quantities (200- .•')()() lbs. to the mix). 
 
 In mixing the plaster of Paris and silica, it is not necessary to 
 do any sifting, because the specified materials may be obtained 
 evenly and definitely graded. All that is required is a thorough 
 mixture icithout excess ive trituration. 
 
 A very efficient small mixing apparatus may be obtained from 
 The J. II. Day ('o., Cincinnati, Ohio. It is known as the " Hunter" 
 (experimental size), and will handle from seven to eight pounds of 
 material. The ingredients arc weighed out, placed in the container, 
 and the a|)paratus revolved slowly for twenty-five or thirty minutes. 
 This produces a uniform and intimate mixture without crushing 
 or grinding the plaster. This point is very important, and if smaller 
 cpiantities are mixed in a mortar, it is important to use very light 
 pressure in order not to crush the ])lastcr particles. The mixed 
 material, of course, should l)c i)n)perly stored and protected against 
 moisture. 
 
 Investments, Directions for Use. — The soldering investment 
 should be mixed quite thick. The thicker, the better, up to a cer- 
 tain limit, of course. If mixed too dry, the plaster-of-Paris content 
 does not obtain sufficient moisture to crystallize i)roperly and 
 act efficiently. A good consistency is 42 to 4.'^) grammes powder 
 to each I.') c.c. water or 27 dwts. C^lVoy) to \ fluid oz. water. 
 
 > Uiililtlc.-' ami TmiIIi proiliicol iiixiii atli-iiipliiiK t<' comliiiK; iiiveisliiii-iit coiiipouiKl 
 ami wa»<T, arc often caiiHcd li.v dirt or hucIi impurities as riiica, etc., conlaiiicd in 
 tlic silica. 
 
398 DENTAL METALLURGY 
 
 The inlay investment should be mixed in a proportion of 35-36 
 grammes powder to 15 c.c. water, or 23 dwts. (Troy) powder to ^ 
 fluid oz. water. This quantity is sufficient to fill an ordinary inlay 
 flask. 
 
 These proportions produce a mixture that allows ample time for 
 manipulation, provided considerable time is not spent in adding 
 a little more water, a little more powder, etc. The setting time of 
 the -plaster naturally controls the setting time of the ichole mixture, 
 and as the action of retarding agents, added to control the set of plaster 
 is sometimes indefinite, and often harmful, it is advisable not to attempt 
 to interfere with the normal setting time of the plaster. 
 
 The compound, if mixed without any unnecessary delay, sets 
 sufficiently slow for all ordinary operations. It is the author's 
 practice to have on hand a number of cork-stoppered bottles con- 
 taining the dry compound (weighed), and a number of rubber-stop- 
 pered vials containing water (measured) . The accurately-measured 
 powder and water are thrown simultaneously into the mixing bowl, 
 and having no bubbles or froth (as with graphite compounds)^ 
 to contend with, the mix can be made ready for use in from 30 to 
 40 seconds, thus allowing ample time for coating the pattern and 
 imbedding in flask. 
 
 This method is superior to using the automatic weighing appara- 
 tus furnished by some of the compound manufacturers, as they are 
 often either inaccurate or not sufficiently "flexible." 
 
 It is not advisable to attempt to invest more than one pattern 
 at a time. 
 
 Another advantage in using measured and stored water lies in 
 the fact that it is, when used, at room temperature, and not at 
 hydrant temperature, and the room temperature water does not induce 
 a further contraction of the wax pattern during the process of infesting. 
 
 Heating of Investments. — The soldering investment may be 
 heated quite promptly upon setting. Boiling water does not affect 
 it materially and the wax may be washed out thoroughly, the case 
 fluxed and immediately placed on the heat, moderate at first and 
 
 ' Most of the compounds that contain flake graphite are very difficult to mix 
 on account of the air content in the flakes and their tendency to "float." 
 Such a compound requires a considerable period of time to mix, and therefore a 
 retarded plaster is usually employed. Nodules, or "ghosts" on castings, occur 
 frequently because the material is not "dormant" until "set." One manufacturer 
 of such a compound claims that it is the plaster and not the graphite that causes 
 the bubbles. This statement appears quite contrary to the facts. Kerr's "Graphite" 
 Investment is made with previously-treated graphite and it is the best graphite 
 investment that the author knows of, 
 
REFRACTORY MATERIALS 399 
 
 then brought up quite rapidly to a good red heat prior to the actual 
 solderiug operation. 
 
 It IS the inefficient and inanfficient heating of the invested leork 
 that is partly to blame for the "popular" demand for "easy-flowing" 
 solders. Properly-heated inrestments facilitate the flow of normal 
 or even high-fusing solder. 
 
 A small quantity of potassium sulphate or sodium chloride may 
 be used to hasten the setting of the investment, but that is rarely, 
 if ever, necessary because it sets quite promptly if mixed to the 
 proper consistency. 
 
 The inlay investment should be permitted to set for at least 
 thirty minutes, to insure a fair crystallization (so-called "initial 
 set") of the plaster. The flask should then be placed over a low 
 heat and kept there until the moisture disappears and the wax 
 begins to diffuse and carbonize. The heat is increased somewhat, 
 during the latter part of this operation, and still further increased 
 until the mould is brought up to either a dull red heat (for cold 
 mould) or a bright red heat (for hot mould). 
 
 The initial stages of heating must be at a temperature that will 
 not permit the wax to run out of the mould, as it is important that 
 the wax be absorbed in the mould. Forced heating and a generation 
 of steam during the initial stages of the drying process will force 
 the wax out of the mould and produce a rough interior, which in 
 turn will show its effects upon the casting, the resultant casting 
 being rough, incorrect, and usually unfit for use. It is, of course, 
 essential to confine and concentrate the (higher) heat in order to 
 l)ring the mould to the proper temperature within a reasonable 
 jH'riod of time. 
 
 Prolonged heating of the investment is even more dangerous 
 than underheating, as plaster of Paris, which is the binder, shrinh 
 in proportion to the time that it is exposed to heat. The total heating 
 operation for an ordinary mould (inlay, etc.) should not exceed 
 fifty minutes or an hour at most. It may be divided into three 
 periods, say twenty-five to thirty minutes for low drying heat, 
 then increased somewhat for ten to fifteen minutes, and finally 
 subjected to the highest heat for not more than from ten to fifteen 
 rniiMites. 
 
 It is |>erniissible not to heat a case until two or three hours after 
 the investment has been mixed, but if it is permitted to stand for 
 ;i day or two, and loses all moisture, if then heated and cast, the 
 n>iilt;itit casting is apt to be very jjoor. It is hard to determine 
 
400 DENTAL METALLURGY 
 
 the actual principle involved, and it is not important to do so, but 
 the fact does exist. In addition, under such conditions, the invest- 
 ment is very apt to crack or split upon heating. The author usually 
 heats and casts into "green" moulds, but has found that a dry 
 mould, if moistened prior to heating, appears to behave almost as 
 well as a "green" mould. If the mould is only a few hours old it 
 is moistened slightly, but if it is more than a day old, it is placed 
 in water until saturated to the extent of a "green" mould. 
 
 Both the soldering and casting investment compounds are prac- 
 tically immune to "checking" or ''cracking," even under the most 
 severe heating conditions.^ 
 
 FLUXES. 
 
 Fluxes for Soldering and Casting. — For sweating, soldering or 
 melting metals in the construction of bands, crowns, bridges, or 
 castings, the selection and use of the proper flux or fluxes is a matter 
 of the utmost importance, especially if the metals or alloys used 
 are oxidizable or volatile when subjected to heat. 
 
 Ordinary borax, or calcined borax, has been the principal flux 
 used for this purpose. It has been almost universally used by 
 jewelers, and the dentist has followed suit. There is, however, a 
 considerable difference between the class of work that the jeweler 
 and the dentist perform. 
 
 In dental soldering, we use higher grade solders and a consider- 
 ably higher heat, during the various operations. As ordinary borax 
 melts at a comparatively low temperature, it does not act as effi- 
 ciently during the higher temperature stages as the requirements 
 demand. The tendency of borax when considerable heat is applied, 
 is to liquefy strongly, and run down to the deep portions, leaving 
 the other portions, that it is desired to solder, insufficiently pro- 
 tected. Dr. Peeso recognized this long ago by using a combination 
 of borax and boric acid, which combination melts at a higher 
 temperature than borax alone, does not liquefy so readily, stays 
 on the surface, protects the work longer, and is more efficient in 
 every way. 
 
 1 This fault is inherent in most investment compounds; the causes are numerous 
 and principally due to the producers ignoring the physical laws governing the selec- 
 tion and compounding of materials for the purpose. One of the principal errors in 
 this connection is the attempt to form a "concrete like" mass without realizing 
 that there is a very great difference in the behavior of dental investment compounds 
 and concrete \ised in building operations. 
 
FLUXES 401 
 
 All ffficifut Hux that has served very satisfactorily in the author's 
 hands tor a considerable period of time is the following: 
 
 FORMULA FOR SOLDIERING FLUX. 
 
 Tarts. 
 
 C. P. Lorax filass (fused) -j-j ^' 
 
 C. r. Ijorif iK-kU not fused) ■^■'5 
 
 C. P. silica 10^ 
 
 Total 1"0 
 
 The ingredients are placed in a clean clay or sand crucible, and 
 brought to a fair red heat. They combine quite readily and when 
 ciuite fluid, the mixture is poured intt) cold water. As this glass is 
 quite soluble, it must be removed from the water as soon as possible, 
 dried, and ])ulverized to ])ass an cSO mesh sieve. It ma>- be pul- 
 verized without difficulty, as the particles are very frail and brittle. 
 
 This flux may be used either in the i)o\vdered form or comi)ounded 
 with " vaseline," to form a paste, or dissolved in boiling water and 
 the saturated solution used. In the liquid form, it will be found 
 suitable for all general oper-titions where the work can be heated, 
 so as to drive off the moisture and thus leave a coating of the Hux, 
 a« in bands, crowns, etc. When the work is in an investment, the 
 grease flux will be found most useful, as it may be applied just after 
 the case is washed out and still warm. The carrier (vaseline) flows 
 down into the deep ])ortions and crevices, carrying the i)articles 
 of flux along. The ])o\v(lered dry Hux can be used on invested work 
 under the blow-])ii)e when more Hux is recpiired. The strips of 
 solder can, of course, be coated with either the \k\\nd or the grease 
 flux, and heated prioi' to use. 
 
 This solficriiiri Jliix in n jr.ncdvrctJ j'onii irill also he used <is flie 
 hdse for hutli the rrdiirin;/ and oxidizing Jlu.res tu he discussed. 
 
 It is important that the forms of l)orax and boric acid speciHcd 
 be adhered to, because of the variable amount of water that these 
 materials contain when i)urcliase<l. 
 
 The formula of borax glass is Xa-BiOv, whereas ordinary borax, 
 either powdered or crystals, contain a considerable i)roi)()rtion 
 of water, which i> evident from the formula XaoBiOy + U)Il2(). 
 Therefore the borax glass is |)referable to the ordinary borax con- 
 taining water, becaUKc it occupies much less space, and is therefore 
 more convenient to handle in small crucibles. However, if ordinary 
 borax is used, the water content must be calculated and jjrovided 
 for in weighing out the iiigicdicnts. The boric acid used does 
 I'll 
 
402 DENTAL METALLURGY 
 
 contain water, as will be seen from the formula H3BO3, because it 
 is more stable than the fused boric acid B2O3, and more readily 
 obtainable. The silica should be pure, and in the form of a fine 
 powder, so that it may combine readily. The grade (F. F. W.) 
 used in inlay casting investment is quite suitable. 
 
 Reducing Flux. — In connection with the casting process, it is 
 necessary to treat buttons of gold both during casting, and before 
 recasting, with a flux that will take care of the acquired impurities. 
 Very often there have appeared statements to the efi^ect that a 
 mixture of potassium nitrate and borax be used to cleanse buttons 
 before recasting. This statement has been, in a good many cases 
 to the author's knowledge, misunderstood. Potassium nitrate is 
 an excellent oxidizing agent, and does remove base metals, but its 
 use in treatment of casting buttons is contraindicated because 
 generally, when casting gold alloys containing copper, etc., it is 
 desired to retain the base metal, the copper, in a reduced metallic 
 form, and not in an oxidized form. Consequently, if a flux is to be 
 used, it must be of a distinctly reducing nature. 
 
 Reducing fluxes are used extensively in assaying and smelting 
 operations, and their properties are well-known. In the case of 
 casting, it is rather difficult to utilize all the benefit that may be 
 derived from a reducing flux, on account of the difficulty of apply- 
 ing same to the molten metal, while it is exposed to the blow-pipe 
 flame which blows instead of drives off the flux almost as fast as it 
 is applied. Therefore, to obtain any considerable benefit from a 
 reducing flux, it is necessary to not merely apply same while the 
 gold is fluid under the blow-pipe, but also to sprinkle an additional 
 amount in the manner described in the following: After placing 
 flask on casting apparatus, place button or nuggets of gold into 
 crucible, melt without flux until the mass of gold assumes a 
 spherioidal form and completely covers the sprue hole. Then 
 apply some flux by sprinkling, continue the melting until the gold 
 is in a proper state of fluidity for casting, then remove flame, add 
 some more flux, and instantly apply the casting pressure. 
 
 FORMITLA FOR REDUCING FLUX. 
 
 Parts. 
 
 Soldering flux (base) • . . 40.0 
 
 Borax glass 30.0 
 
 Argol 25.0 
 
 Animal charcoal . , . . . 5.0 
 
 Total 100.0 
 
FLUXES 403 
 
 Argol is the commercial term for crude potassium hitartrate 
 KHC4H4O6 (cream of tartar) and has a higher reducing power 
 than piu-e cream of tartar. If the latter is used, it should be 
 increased to about 25 parts, and the soldering flux and borax glass 
 content reduced in proportion. 
 
 A fliLx of this character will practically prevent the bringing into 
 the casting, of oxidized material, and can be used to advantage in 
 remelting and cleansing buttons of gold for recasting. 
 
 The author's procedure for this operation is as follows: After 
 a casting is made, the residue button is placed into hydrofluoric 
 ac-id for fifteen or twenty minutes, removed and melted with the 
 blow-pipe on a charcoal block, using the reducing flux, which, in 
 addition to reducing the oxidized copper in the button, combines 
 with the silica, traces of which may adhere to the button. After 
 the button is melted, and the fliLX used has segregated into a globule, 
 the blow-pipe is removed and a small quantity of ammonium' 
 cldoride is sprinkled on the button. As soon as the button has 
 solidified, and while still red hot, it is plunged in dilute hydrochloric 
 or suli)huric acid. Most of the glass formed by the flux will splinter 
 off. If any considerable quantity adheres, it may be removed by 
 l)oiliiig in the same acid. 
 
 Oxidizing Flux.— Potassium nitrate is a most excellent oxidizing 
 agent and rem()\es the base metals, the only objection being the 
 strong fumes which are given off during the melting process. 
 -Mthough the operator should rarely attempt to do refining, it is 
 well to have a suitable oxidizing flux that will not give off the 
 objectionable fumes characteristic of potassium nitrate. 
 
 FORMULA FOR OXIDIZINC FLUX. 
 
 Si)lr|crilltt flux (l);isc) 
 
 l'')l:i.s.-.iiini cliloraic 
 
 Sodiiiiii pfilxjratu •>5 
 
 J'uits. 
 
 55 . U 
 20.0 
 
 Total 
 
 100.0 
 
 This Hux will be found useful for revivifying buttons of gold 
 which are contannnated. it is sufficiently powerful to volatilize 
 .such inipurities as tin, cadniiuni, bismuth, etc. It will combine 
 with adherent investment compound and not attack copper very 
 .strongly, .^., that a button of gold that has been u.sed several times 
 and is quite shiggi>li and dirty, can be usually brought into good 
 shaijc without diffif iilf\-. 
 
401 DENTAL METALLURGY 
 
 A button treated with this flux should be cleansed in acid, as 
 previously described, and then remeUed with the reducing flux 
 prior to use for casting. 
 
 In cases of refining, where a stronger action is required, the potas- 
 sium chlorate and sodium perborate can be increased to obtain the 
 same efficiency that a high percentage of potassium nitrate would 
 give without the objectionable fumes characteristic of the latter. 
 
 It is expected that prepared flux made according to the formulae 
 given will be very shortly available from the supply houses. Until 
 such time, a modification of the soldering flux formula, Avhich 
 also acts as a base for the reducing^ and oxidizing fluxes, is given 
 herewith for the benefit of those who have not the facilities for 
 fusing and pulverizing the material. These ingredients make a 
 flux which appears to work much more satisfactorily than ordinary 
 borax or any of the secret preparations purchasable. 
 
 FORMULA FOR SOLDERING FLUX (SUBSTITUTE). 
 
 Parts. 
 
 C. P. borax glass 50.0 
 
 C. P. boric acid 43.0 
 
 C. P. sodium silicate (dry powder) 7.0 
 
 Total 100.0 
 
 This is mixed thoroughly in a mortar and must be ground fine 
 enough to pass an 80 mesh sieve. 
 
 The author trusts that his remarks upon the importance of pro- 
 ducing castings with all the metal in a reduced form, and not in a 
 partially-oxidized form, will be given some consideration by the 
 reader, as this problem, on an immeasurably larger scale, has been 
 and is one of the most important ones in the application of indus- 
 trial alloys, and is being coped with successfully. 
 
 ' There are a number of better-reducing agents than those suggested by the 
 author, used industrially. They are not mentioned because of either difficulty of 
 application under casting conditions, or on account of not being obtainable in 
 small quantities. A study of the methods used in deoxidizing copper, brass and 
 bronze, is suggested to those particularly interested. 
 
kEMOVABLE HRllHlE-WORK 405 
 
 Table i\ .— meltixg points of the new series of alloys and 
 standard dental golds. 
 
 °F. Al.LOY. o C. 
 
 2100 *-'Ela:^tic"' (;..1(1 1150 
 
 2975 *Plate No. 1 1135 
 
 Ut7.". *Plate No. 2 1080 
 
 U»(3() Type 4 Clasp 1070 
 
 1945 Pure Gold lOfi.'J 
 
 194.-J *rasting Gold 'A" 1063 
 
 194.") *Casting Gold "B" 1063 
 
 194.5 ''Green Gold" (App. An SO per cent. A<i. 20 per cent.) 1001 
 
 1900 *CastingGold '-B" 10.3.5 
 
 1900 Light 22-K. Plate 1035 
 
 1860 Medium 22-K. Plate 1015 
 
 1860 Type 3 Cla.sp 1015 
 
 182,5 Dark 22-K. Plate 995 
 
 1800 *Casting Gokrr" 980 
 
 1760 Light 20-K. Plate 960 
 
 173.5 Coin Gold (21. 6-K.) 946 
 
 172.5 Type 2 Clasp 940 
 
 1650 *Gold Solder No. 84 900 
 
 162.5 Gold Solder for 22-K S80 
 
 1600 Type 1 Clasp 870 
 
 1550 *Gold Solder No. 76 840 
 
 1525 Gold Solder for 20-K 820 
 
 1450 *Gold Solder No. 68 785 
 
 142.5 Gold Solder for IS-K 77O 
 
 The ten alloys- innrked " * " eonfitlfitfe the new series. 
 
 They are all uniform in color with the exception of "Elastic" 
 
 gold which is similar to platinum in color and Casting Gold " A " 
 which i.s similar to |)ure gold in color. 
 
 SOME OF THE APPLICATIONS OF THE NEW SERIES 
 
 OF ALLOYS IN THE PEESO SYSTEM OF 
 
 REMOVABLE BRIDGE-WORK. 
 
 .\- will l)c .seen from the preceding table, the series of alloys 
 olfers a large range of variation in melting point, over the ordinary 
 alloys, thus facilitating the i)crforniancc of successive soldering 
 o|)crations. 
 
 Construction of Bands, Floors, and Inner Caps. As has been 
 previously stated, coin gold is the most suitable alloy for the con- 
 struction of bunds, floors, etc. It is therefore necessary to use 
 coin goM or its ct|uivalcnt in the uew scries of alloys'. The band 
 
406 DENTAL METALLURGY 
 
 should therefore be made of the No. 2 i)late (M. P. 1975° ¥., 1080° 
 C), and united^ by soldering with the next lowest fusing alloy, 
 namely, Casting Gold ^'B" (M. P. 1900° F., 1035° C). 
 
 The floor is also prepared of No, 2 plate and soldered to the band 
 with Casting Gold " C" (the pliers grasping the band at previously- 
 joined portion). 
 
 The method will make, for all intents and purposes, a seamless 
 cap. The melting point of the soldered junctions will still be con- 
 siderably above that of coin gold. The tube may then be attached 
 with the No. 84 solder. 
 
 Inner caps for telescope crowns are made in exactly the same 
 manner. As the hardness and tenacity of the No. 2 plate is the 
 same as that of coin gold, the same gauges of plate are to be used 
 as with coin gold. The casting gold, if used as solder, should be of 
 practically the same thickness as ordinary gold solder, approximate 
 28 gauge B & S, or preferably thinner (30 to 32 g.). 
 
 Outer Half Bands and Telescope Crowns. — After completing 
 the inner cap and tube, the floor is made of No. 2 plate, the split 
 pin attached to it with No. 84 solder and the half band fitted and 
 attached with 84 solder. 
 
 For telescope crowns, the outer band is made of the No. 2 plate 
 and the joint soldered with casting gold B. The wings are made of 
 No. 2 plate and soldered to the band with Casting Gold "C." The 
 cusp is swaged of No. 1 plate (higher fusing than pure gold), filled 
 with Casting Gold "C" in the same manner as a pure gold cusp 
 is filled with coin gold, and attached to the previously-completed 
 outer band and wings with No. 84 solder. 
 
 If the cusp is to be cast, Casting Gold "B" or "C" should be 
 selected according to the blow-pipe used, and attached to the con- 
 toured band with No. 84 solder. 
 
 As all of the alloys of the series used in this operation are of the 
 same color, and the No. 84 solder is actually 20-K. fine, there will 
 be no line of demarkation evident in the finished work. 
 
 Inlay Abutments. — The shell for the inner inlay may be cast 
 with Casting Gold "D" and adapted to the cavity by burnishing. 
 The tube is then soldered and the whole completed with No. 84 
 solder. The outer inlay matrix can then be made, using the com- 
 paratively soft, but high-fusing plate-gold No. 1, and Casting Gold 
 "C," instead of pure gold and coin gold. 
 
 1 See Dr. Peeso's method of band preparation for sweating. 
 
REMOVABLE BRIDGE-WORK 407 
 
 Construction of Saddles. The saddles, if swa^vd of i)latiiiuni, 
 may he reinforeed with ('astiii<;- (lold "H" or "(\" instead of coin 
 gold, or the saddles may he swaj^ed of No. 1 phite (softer than No. 
 2) and reinforced with ('asting (Jold "('." If the saddles are to 
 be cast, ('asting Gold "B" or "C" slionld be selected according to 
 the blow-pipe used. 
 
 Construction of Dummies.— In constructing the dummies (if 
 all porcelain), the bases and dowels may be cast with either "B" 
 or "(\" and attached to the saddles with the 84 or 76 solder. 
 
 They may also be made by burnishing 34 g. pure gold backings 
 to tlie i^repared porcelain crowns, fitting and soldering dowels made 
 of "Elastic" gold, to the backings (or boxes), and attaching the 
 completed backings to the saddles with 84 or 76 solder. 
 
 The author cannot close without calling attention to the fact 
 that a broad conception of the scientific principles involved in the 
 chemical and physical l^ehavior of the various materials utiUzed 
 in connection with the construction of prosthetic restorations, is 
 a most potent factor toward the attainment of the ideal. 
 
 He has been aided materially in arriving at the conclusions pre- 
 sented lierein by the kindness of Mr. H. C. Ney, president of the 
 J. M. Xey (V)mj)any, who unstintingly placed at the author's 
 (•(mimand all the facilities of their extensive metallurgical works 
 in Hartford. 
 
 He also wishes to thank Dr. Peeso particularly, for accepting 
 this eontribution for presentation under his auspices. 
 
CHAPTER XIX. 
 
 THE USES AND THE VALUE OF RADIOGRAPHY 
 IN CROWN AND BRIDGE-WORK. 
 
 By FRED'K K. ream, M.D., D.D.S., 
 
 NEW YORK CITY, 
 AND 
 
 RICHARD H. RIETHMtTLLER, Ph.D., D.D.S., 
 
 NEW YORK CITY. 
 
 The first question that interests the architect or the construction 
 engineer is the nature of the ground upon which his edifice is to 
 rise, and no effort is spared to ascertain fully the character of the 
 foundation and to provide by every available means its stability, 
 thereby insuring the durability and safety of the proposed structure. 
 It is upon the same principles that the successful crown and bridge 
 worker calls to his aid all the means available for ascertaining the 
 condition of the tissues, both hard and soft, before laying out a 
 detailed plan for the construction of the prosthetic appliance to be 
 inserted in each case. This precaution not only spares the operator 
 the humiliation of failure, the loss of valuable time and material, 
 and untold annoyance, but it also protects the patient against 
 preA'entable incon^Tnience, and safeguards the public's faith in the 
 efficiency of crown and bridge-work. The bridge worker's chief 
 consideration, however, as in all dental operations, no matter of 
 how apparently trifling a nature, must be the patient's health. 
 Since Dr. William Hunter, of London, and after him scores of others 
 have arraigned the dental profession, and especially the crown and 
 bridge worker, for causing oral sepsis with all its dire sequelae by 
 their disregard of the physiologic and anatomic bases of their 
 work, the responsibilities involved in any intervention in the 
 human mouth are being more fully realized than ever before. 
 The spectre of "septic dentistr}-" has alarmed practitioners and 
 patients alike, especially since the findings of such investigators as 
 Billings, Rosenow, Flexner, Mayo, Grieves, Hartzell, and others 
 have substantiated Hunter's timely warnings. 
 
 And indeed, no other dental operation is more conducive to 
 
MKAXs Foix' i)i.\(;.\(>s[\(; thk fif.i.}) of oi'Fuatios 400 
 
 bringing ahoiit chronic septic conditions, locally as Avell as systemat- 
 ically, than i)oorly constrnctcd crown and l)ridgc-\vork. The harm 
 done hy suc-h work of inferior qnality is all the greater, since it is 
 often not recognized nntil far-reaching damage is done not only to 
 the teeth and the month, hnt to the ])atient's general health. A 
 tooth lost, therefore, may he i)referal)Ie to a tooth "entombed in a 
 golden casket." 
 
 Means for Diagnosing the Field of Operation. — Before the discovery 
 of the ,/-ra\ l)y i'rofcssor W. K. lii'intgen, in 1895, and its practical 
 utilization in radiography, a well-developed i)athological sense, an 
 intimate knowledge of general and special dental anatomy, delicate 
 palpation, and \ast experience were the only means for diagnosing 
 the condition of the hard and soft tissues of the jaws, of the teeth 
 in general and the abutments in special, and of the presence of 
 apparent or ob.scure foci of infection; but it is self-evident that 
 these diagnostic agents alone ofl'ered no certain guarantee for a 
 correct diagnosis in every ca.se. The most reliable diagnostic data 
 are furnished by the radiograph, this reliability standing in direct 
 ratio to the radiographer's ability in making exposures and interpret- 
 ing the resultant picture. A poorly taken or incorrectly interjjreted 
 radiograph is undoul)te(ll\' almost worse than none, since an error 
 in technic or interi)retation would induce the bridge worker to 
 proceed with his operations upon false premises. l^Or this reason, 
 the modern tendency toward specialization seems commendable. 
 The average crown and bridge worker will find himself too busy 
 to devote the necessary time and study to accjuiring a perfect 
 technic in radiography. On the other hand, his coo])eration with 
 the radiograj)her is indisj)ensable; he must be able to give to the 
 specialist intelligent directions as to the special features he wishes 
 to have elucidated in each case, and he must be sufficiently well 
 versed in the interpretation of pictures to recognize the j)athological 
 or anatomic facts disclosed and to suggest, if necessar\', a rejK'tition 
 of the radiographic examination under altered conditions of position, 
 time of exposnre, or fpiality of rays employed. \\ lieu such intelli- 
 gent coojM-ration j)re\ails l)etwe<'n radiographer and bridge worker, 
 the .r-ray will furnish a clear insight into the conditions of the oral 
 ti.ssues invoked in a crown and bridge ojM'ration, hence ensure the 
 successful accom[>lishmciit of the |)roj)osed o])eration; it will ])rove 
 an invaluable pro])hylactic agent against failure due to faulty 
 diagnosis and a most imj)ortant factor toward prosthetic efficiency; 
 it will a?<sure the patient of a correct interpretation of his case, the 
 
410 
 
 RADIOGRAPHY IN CROWN AND BRIDGE-WORK 
 
 best possible prosthetic repair of his dental defects and adequate 
 services for his expenditures in time and money; and it will prevent 
 oral sepsis with all its grave sequelae. 
 
 Books on Dental Radiography. — ^IVIanifestly, it cannot be the pur- 
 pose of this chapter to teach dental radiography in all its phases 
 and to make an .r-ray specialist of every crown and bridge worker. 
 For autodidactic purposes, we recommend such books as Elementary 
 and Dental Radiography, by H. R. Raper, Dental Radiology by 
 F. L. Satterlee, and a perusal of the numerous articles on this 
 
 Fig. 661 
 
 subject which have from time to time appeared in dental magazine 
 literature. The main object of this essay, which naturally must 
 have a limited scope, is to point out in how many respects radi- 
 ography is wonderfully helpful, in fact absolutely indispensable to 
 the crown and bridge worker. 
 
 Hints Concerning Outfit, Technic, Keeping of Records, and Interpre- 
 tation. — It cannot be our purpose to mention the various radiographic 
 outfits now in the market, or to compare their relative merits and 
 fitness for our special work. Suffice it to say that the radiographs 
 
IIIXTS CnxCERNING OUTFIT, TECH NIC, ETC. 411 
 
 Fig. GG2 
 
 Fifi OG'i. — lAiOii KlfiHR (liaphniKin. CJut-fjut HUKKf;ste<l by Dr. F. K. Ream, and 
 ijianiifantured by the Scheidel We.iU'rn X-ray foil f 'o/iipaiiy for making expoaunvs 
 for iii»i>er and lower jawH. The out-fjut providcM the pro|)('r aiiuli; for tiiukiii>; 
 exjjoHureM in the iipijer jaw, hy holding it directly againHt tlic face. (See FIks. 004 
 and (V'tij). 
 
412 RADIOGRAPHY IN CROWN AND BRIDGE-M'ORK 
 
 \ 
 
 Fio. 6fi4 
 
 Fig. OB.j 
 
 Fig. 666 — Lead box for protecting unexposed films. (Courtesy of American 
 X-ray Equipment Company.) 
 
lUXTS COXCKRMXG OUTFIT, TEVILMC, ETC. 
 
 4i:5 
 
 shown in these pages ha\e been made exchisi\el\" with a Scheidel 
 Western X-ray Coil Company outfit as shown in Figs. 661 and 662, 
 which has given entire satisfaction. As an accessory to this outfit, 
 the cut-out led gUiss diaphragm, suggested by l\eam and ilhistrated 
 
 I'k.. (i(i7. I'ortaljlc rlark-rooiri box for dcvflopiiig films. (Couitcs^- of Ainciiciii 
 X-ray Equipinoiit C'ompany.) 
 
 ill l''ig. fi6:!, Il;^^ proNrd of gir;it liclj) in making cxp<»snres in the 
 upper ;in(l Ntwcc j;i\\s. 'i'liis cut-out proxides the proper angle 
 for making cNiJosnres in tlie upper jaw by holding it directly agaitist 
 the face, as shown in I''igs. 661 and 6('>."). An a|)pliance for holding 
 
414 
 
 RADIOGRAPHY IN CROWN AND BRIDGE-WORK 
 
 the patient's head at rest during exposures of longer duration is 
 depicted in Fig. 676. To protect unexposed fihns or plates against 
 untoward action of the a:-rays, they are kept in a led box of a design 
 
 Fig. 668. — Frosted white and ruby lamp for developing and reading films respectively. 
 (Courtesy of American X-ray Equipment Company.) 
 
 Oatk 
 
 F. K Rl\«.'«« M ! , Ci V 
 
 :.F TEETH 
 
 )EWT.ii R'i.DiOGhPF 
 
 Fig. 669 
 
IIIXTS COXCERXrXG OUTFIT, TECHXIC, ETC. 415 
 
 illustrated in Fig. 666. The development of exposed films or plates 
 is made according to the well-known chemical principles and 
 routine practice adopted in photograph}'. Since usually, develop- 
 ment of plates or films immediately or soon after exposure is desired, 
 both operator and patient being anxious to arrive at a definite 
 diagnosis, the portable dark-room box for photographic develop- 
 ment shown in Fig. ()()7 will prove a valuable accessory which can 
 
 I'll.. 070. — Position for making exposures of cuspid and lalcral. Patient hdidin}, 
 
 film in mr)utli. 
 
 be handled either by the radiographer himself or by his assistant 
 after some training, as a substitute for a special dark-room. This 
 portable dark-room box docs away with the necessity of setting a 
 room or j^art thereof asid<' as a (hiik-ronni, and is practical in c\-ery 
 respect. For <levelo])ing, if a dark-room is available, or for "read- 
 ing" the devel(jped film or plate either while it is still wet or after 
 drying, a combination frosted white and ruby lanij), as shown in 
 Fig. ()(i<S, is useful. A holder in card form of a diaj)hanous material 
 
416 RADIOGRAPHY IN CROWN AND BRIDGE-WORK 
 
 resembling celluloid, or, better still of black cardboard (see Fig. 
 669), on which the patient's name, the date of exposure and the case 
 number is A\Titten, serves as a holder for the developed film, and 
 
 Fig. C)71. — Position for taking upper right teeth, posterior to cuspid. 
 
 permits of convenient liandling, interpreting, and filing of the case 
 for ready reference. It will usually be found that the negative 
 presents finer details than a print made therefrom, the more 
 delicate shades often being lost in prints. 
 
IIIXTS COXCERMXG OUTFIT, TECHNIC, ETC. 417 
 
 In order to obtain a comprehensive view of the field of operation 
 in all its details, and to arrive at definite conchisions concerning 
 the patient's dental condition and the operative measures dictated 
 thereby, it is preferable, in fact most desirable that, instead of 
 securing a rontgenogram of only two or three teeth, a complete 
 series of exposures be made, thus ensuring a complete vision of 
 
 Ik.. <i12. — Ponitiidi for takiiiu four upper aiiU-riur U'otli. Patient i.s liuldiug 
 film in mouth by closing teeth. 
 
 tlic fi<'ld Jiiifl a strategic map, as it were, by win'cli tlic operative 
 ])ni<<'<liir(s will be guided. 
 
 Ill making exposures, tlie patient's cooperation must be solicited 
 for holding tin' film in its proper position in sudi cases as are shown 
 in P'igs. 070, ()71, and 074. The patient's posture, the position of 
 the apparatus and tube, and the maimer in which the patient 
 should hold the film in the mouth when making exposures of the 
 upper lateral and cuspid are illustrated in Figs. 070. For taking 
 u radiograph of right upper teeth ])osterior to the cuspid, the 
 27 
 
418 RADIOGRAPHY IN CROWN AND BRIDGE-WORK 
 
 various units are arranged in the positions shown in Fig. (371. 
 Closing of the teeth for holding the film in place is resorted to in 
 making an exposure of the upper four anterior teeth, as shown in 
 Fig. 672. In similar manner, a large film is placed across the 
 teeth and held in position by the patient's closed mouth in exposures 
 of the lower anterior teeth (see Fig. 673). In taking radiographs 
 
 Fig. 673. — Position for taking exposures of lower anterior teeth. Large film is 
 placed directly across the teeth, patient closing mouth and holding film in position. 
 
 of lower teeth posterior to the first bicuspid, the arrangement of 
 the units is made as shown in Fig. 674, the patient holding the film 
 in place with his finger. P'or obtaining radiographs of impacted 
 third molars, the patient's posture must be given especially careful 
 consideration. In such cases, the use of large plates and trans- 
 illumination of the whole thickness of the head becomes necessary, 
 as is shown in Fig. 675, where the patient is being examined for 
 
iiixrs coxcKhMxc; outfit, techmc, etc. 
 
 419 
 
 impacted lowei third molars. In exposures of the maxillary sinus, 
 wliere a longer exposure is needed, the head is held in position on 
 the plate by a head clamp as shown in Fig. 07(). The ray must be 
 delivered directly on a line with the orbits, the edge of the cone 
 to rest at the auditor}- canal. The anterojxKsterior position for 
 making maxillary simis exi)osures, and the manner of holding the 
 
 I II.. f.ri.- I'.j.-,itioii U,t takiii« i-\\,uMm- ol trclh |)(j.-i.Ti(,r I.. l<nviT lir.st liicii.spid. 
 
 head firmly in position on the plate by means of the head clainji 
 are demonstrated in Fig. (i77. As an aid in .securing the proper 
 position of the head in maxillary sinus c\i)osures, the angle recom- 
 mendefl by Dr. F. .M. I.aw. of .\eu V(»rk (see Fig. (i7N), can !)(« 
 employed to great arlvantag*'. 
 
 A.side from the position of the patient's head, ihc arrangement of 
 the various units of the apparafn>, the angle of incidence of the 
 
420 
 
 RADIOGRAPHY IN CROWN AND BRIDGE-WORK 
 
 ray, etc., the time of exposure and the employment of a "hard" or 
 "soft" tube are of great importance. These latter factors are 
 determined by the nature of the tissues to be examined and the 
 
 Fig. 675. — Position for taking impacted lower third molars. 
 
 diagnostic purpose of the radiograph, and their correct application 
 and blending with the former factors are a matter of judgment and 
 experience and constitute the chief elements of the radiographer's 
 art. Thus it becomes apparent that the successful radiographer 
 
HIXTS CONCERNING OUTFIT, TECHNIC, ETC. 421 
 
 must c()iiil)iiu' an iutiinatc knowledge of tlie anatomy, i)li\siology 
 and pathology of the field to l)e examined with a complete mastery 
 
 Fr<;. '170. — I'ositioti for taking oxpomire of riuixillary .sinus, showiiiu ln-ad clamp 
 and ijlal4; in jx^Hitiori. Tlie ray must ho fliroftly i>u a line with tlic orbits, and edge 
 of cone at auditory canal. 
 
 of tlie |jriiieij)les of optics, electricity and radiopliotograi)hy, this 
 cornhinatioii Ix-ing of a complex eiiongh nature to warrant 
 specialization. 
 
422 RADIOGRAPHY IN CROWN AND BRIDGE-WORK 
 
 In the interpretation of radiographs, the questions of perspective, 
 of distortions and of the appearance of ^'arions kinds and conditions 
 of tissues in their normal and pathological states play an important 
 
 Fig. G77. — Anteroposterior position for making: maxillary sinus exposures. Head 
 clamp is in position holding head firmly. 
 
I)AX(;ki{s of Till': x hwv 
 
 423 
 
 l)art. The best diagnostic results, no doubt, are obtained from 
 well-developed dense negatives which are best "read" by holding 
 them up against a frosted electric light bulb, as seen in Fig. ()()8, or by 
 laying them against the frosted glass plate of an illuminated shadow 
 box. In thin films or plates which are so often seen, a great amount 
 of valuable detail is lost, in fact, the diagnostic value of poor radio- 
 graphs is worse than nil, as an entirely fault\' diagnosis may result. 
 
 Fii:. (i7K. — Aimlc used and rcioniiiiciiilcd l).\ Dr. 1'. M. J.:i\v, New York, Inr nht.iiniiii 
 proper imsilion in ninkint; maxillary sinus pxixisiiics. 
 
 Dangers of the X-ray to Operator and Patient. Before proceeding 
 to th<' discussion of the practical apphcation of ra(liograi)hy in 
 crown and bridge work, a word of warning should be sounded 
 against careless exposure of operator and patient to the action of 
 the ./-ray. Before this action was fully understood, many cases 
 of dcfiiiatitis, cancer, stcrilitx , insanity, abortion, leukemia, and 
 
424 RADIOGRAPHY IN CROWN AND BRIDGE-WORK 
 
 alopecia were reported, and the pioneer workers in this field have 
 dearly paid the penalty for the ignorance that long prevailed in 
 regard to the noxious influences of the .r-ray upon the human 
 tissues. The lamentable fate of these martyrs of science should 
 render every operator who enters the field of radiography doubly 
 cautious, so as to safeguard his patients' and his own health, even 
 life. A very timely warning in this direction has been sounded by 
 George M. Mackee, M.D., of New York City, who in an article 
 entitled "Radiodermatitis following X-ray Examination of the 
 Teeth," published in the April, 1916, issue of The Dental Cosmos, 
 says, " The operator should realize, that in the a*-ray we have a very 
 powerful and dangerous as well as useful agent; and in order to 
 avoid injury to himself and the patient, he must be acquainted 
 with the physics and the biologic effects of the .r-ray," and he justly 
 protests "against anything but the most scientific rontgenology," 
 and he urges this "not only in order to assure the future of rontgen- 
 ology, but for the legal protection of the operator as well as the 
 physical welfare of the subject." 
 
 INDICATIONS FOR THE USE OF RONTGENO GRAMS IN 
 CROWN AND BRIDGE-WORK. 
 
 Coming now to individual cases of crown and bridge-work in which 
 x-ray examination is not only desirable, but imperative, it is self- 
 evident that the broad basis upon which a prosthetic restoration 
 is to be placed must be of healthy condition, if success of the opera- 
 tion is to be insured. In a great many cases there may have 
 been going on a slow progressive destruction of alveolar process 
 in its entiret}' or at its borders, though the patient was not aware 
 thereof, and purely ocular or digital examination may have revealed 
 no extraordinary condition. 
 
 Root Resorption. — Owing to the presence of irritation of some 
 form or other, the apical or any other portion of one or several 
 roots which are to be employed as abutments, may have been 
 undergoing slow resorption, thus rendering the employment of such 
 roots of extremely dubious value as pillars for reconstructions, 
 unless the condition is duly recognized and, if possible, such 
 therapeutic or surgical procedures have been instituted as to restore 
 a healthy condition. The revelations furnished by careful a:-ray 
 examination of such cases are illustrated in Figs. 679, 680, and 681. 
 
IXDICATIONS FOR THE USE OF RONTGENOGRAMS 425 
 
 Obscure Dental Caries and Pulp Exposure.- 'I1i(> presence of 
 caries in a tooth which is to l)e employed as an al)utinent is not 
 
 Fig. 679. — Resorption of root ends 
 and alveolar border in seeoiul bicuspid 
 and first molar. .VIso unfilled canals 
 and iniptM-fect fining in first and second 
 molars. 
 
 I"iG. 680. — Destruction of alveolar 
 sui)port of crowned tooth that ai)par- 
 cntly was in healthy condition. This 
 Ijictiu'e indicates the necessity for ;r-ray 
 examination. 
 
 I-"i(;. (isi. — Complete ab.sorption of mesial root of lower first molar. 
 
 always reacHly revealed by the usual methods of examination, and 
 even if detected by the.se means, the (le,structi\'e process with its 
 concomitant irritation of the pulp culminating in the exposure of 
 
 Fig. 082. — Extensive carie.s and 
 pulp exi>o.sure on the liiiKua! surface 
 of lower first molar. 
 
 Fro. V)Ki. — Unfilled root canals, ab- 
 .soe8.scd roots, and obs(aire caries in third 
 molar. Tj'iiKual bar on .second bicuspid. 
 
 this organ may have rendctcd llic proposed ;d)Mtiii( iil (ootli unfit 
 for a stable restoration. 
 
420 
 
 kAdiograpiiy in crown And HRibaE-woRK 
 
 The .T-ray will readily reveal the presence and extent of such 
 pathological conditions, and prevent error in judgment and failure 
 of the reconstruction. Cases of this nature are shown in Figs. 
 682 and 683. 
 
 Necrosis. — The detection of rarefied or necrotic areas in any 
 portion of the maxillae, and especially around teeth or roots to be 
 employed as crown or bridge supports cannot but be of vital impor- 
 tance both to the patient and the operator. A pathologic condition 
 of this nature, if overlooked, would not only seriously impair the 
 value of any restoration, but indeed greatly endanger the patient's 
 
 Fig. GS4. — Necrotic area in the region 
 of molar roots and alveolar abfscess. 
 
 Fio. 685. — Rarefied and necrotic areas 
 around roots of bridge supports. 
 
 Fic. 686. — Necrotic area around the first molar and wires placed in roots for purpose 
 
 of radiography. 
 
 health by imbuing him with a false sense of security. Figs. 684 
 to 686 are ty])es of conditions of this description. 
 
 Impactions : Retained, Unerupted or Imperfectly Formed Teeth. — Of 
 all teeth, the third molar is most often subject to anomalies in 
 shape and position, and its utilization as a crown or bridge support 
 therefore largely depends upon a recognition of its condition in 
 each case. Impactions, as illustrated in Figs. 687 to 692 demand 
 timely detection and prompt attention, even if the teeth thus 
 affected play no part in the operative restorative plans, as they 
 may in time seriously interfere with the efficiency of the restoration, 
 
I.\I)/(.\TI()\S Foil' THK r.sVs OF h'dXFdFXOC h\\ MS 42? 
 
 aiul may lead to coinijlications which would justly he hlauied upon 
 the operator's lack of circumspection. The pus areas so frequently 
 foimd in connection with impacted teeth may spread to adjoininji 
 teeth, and thus hecome a grave danger to such teeth, also a prolific 
 source of svstemic infection. 
 
 Fig. 687. — Impacted lower third 
 
 Fig. 088. — Impacted third molar, with 
 
 molar. Owing to the age of this patient pus area around distal surface of crown. 
 
 and density of bony wall, detail is \>ry prolific source of systemic infection. 
 
 lacking. 
 
 Fu;. (ix'.K — Impacted low •! i huil niohn-. Fig. 690. — Lower third molar coni- 
 .Absce.ssed and unfilled root canals of first pletely iml)cdded in the luaiidiMe. 
 
 permanent molar. 
 
 I'"lo. (>'.»! Itii|.:ictcd first bicuspid. 1"ig. 602.— Transversely impacted lower 
 
 tliird molar and cyst. 
 
 Ketaitied <l<'ciduous teeth or unerupteil |)ermaiieiit teeth, unless 
 detected heh»re the iiistitiition of restoniti\'e measures, may 
 well destro\ the most heaiitiful reslorat ion, since the unfitness of 
 a deeidnou^ tooth for an ahntment or the delayed eruption of a 
 
428 
 
 RADIOGRAPHY IN CROWN AND BRIDGE-WORK 
 
 permanent tooth will necessitate the removal and possibly recon- 
 struction of bridge-work. Examples of anomalies of this character 
 are illustrated in Figs. 093 to 696. 
 
 Fig. 693. — Unerupted upper ouspid. 
 
 Fig. 694. — Unerupted and imbedded 
 lower third molar in the mouth of a 
 patient, aged sixty-five years, which 
 gave rise to great suffering. The pa- 
 tient was almost insane from pain for 
 a period of three years. Pressure on 
 the inferior dental nerve together with a 
 pulp exposure was the source of intense 
 agony. Owing to the age of the patient, 
 calcification was almost complete, mak- 
 ing the surgical removal of this tooth 
 extremely difficult. The patient made 
 a good recovery after the operation. 
 
 Fig. 695. — Erupting permanent 
 bicuspid beneath crown of deciduous 
 tooth. 
 
 Fig. 696. — Interlocking of unerupted 
 permanent bicuspid imbedded in crown 
 of deciduous molar. Also root of per- 
 manent first molar. 
 
 Abscess. — The word "abscess" has surely become the bugbear of 
 the dental profession, and to no specialist in dentistry has the pres- 
 ence of this enemy become more awe-inspiring than to the crown 
 and bridge worker. If indicated by discoloration of the crown of 
 the tooth, or by a draining fistula, the unsound state of a tooth 
 and its bony support is plainly enough indicated; but what of 
 the innumerable teeth with blind foci of infection, which give no 
 evidence of their presence for years, and only after a more or less 
 prolonged period of obscure activity manifest their noxious influence 
 
IXDICATIONS FOR THE USE OF RONTGENOGRAMS 429 
 
 ill a remote systemic condition? The utilization of such a tooth 
 in croAvn and bridge-work naturally subjects the patient to untold 
 
 Fig. (iU7. — Alvfolar alwwss in latoriil, cuspid, 
 aud Hr.st bicuspid. 
 
 Via. 698. — Abscess of loft lateral 
 incisor, and imperfect root canal 
 fillings. 
 
 Via. 099. — Badly abscessed root of 
 Irjwer second bicuspid and incipient 
 abscess of molar. 
 
 Fiu. 700. — Abscess at apex of first 
 bicuspid. 
 
 Fio. 701. Abh'C'..-- of lower (ir>l and 
 second bicuspids. 
 
 Fi(i. 702. — First and second molars 
 l)adl,v abscessed and decayed roots in- 
 flicatinn unfitness for crown or bridKC- 
 \vr)rk. 
 
 risk.s, and the crown and bridKc worker has practically no other, 
 or at least no su<li convenient and reliable diagnostic agent at his 
 
430 RADIOGRAPHY IN CROWN AND BRIDGE-WORK 
 
 command for the detection of these foci, as the .r-ray. Hence it 
 becomes his duty to ascertain the true condition of the teeth and 
 their substructures not only in suspected cases, but practically in 
 all cases where restoration is demanded, because none of these 
 cases can any longer be considered normal. If precautions of this 
 nature had been resorted to as soon as the .r-ray became available, 
 the crown and bridge worker could have spared himself the recent 
 arraignment of the medical and dental professions at large, and could 
 Vave a\'oided the jeopardy in which the very principles upon which 
 bis specialty is based have been temporarily placed. Even when 
 an .r-ray examination is made, the interpretation of the residting 
 rontgenogram is a matter of greatest importance, because the 
 mistaken incrimination of a tooth is almost as serious an error in 
 judgment, as is the overlooking and neglect of such a condition if 
 present. Rontgenograms of abscessed conditions probably tax the 
 skill in technic and interpretation of the radiologist to the severest 
 degree, and only pictures of such quality as shown in Figs. G97 to 
 702, should be trusted as reliable diagnostic aids. 
 
 Root-canal Fillings. — While the determination of the vitality or 
 non-vitality of a tooth, so easily accomplished by means of radiog- 
 raphy, can be achieved by other diagnostic means, the utilization 
 of the Rontgen ray in root-canal fillings before, during, and after 
 this operation has become almost a sine qua non of dental operative 
 practice. The crown and bridge worker, of course, is especially 
 interested in the ])rotection of roots which are to serve as supports 
 for his work, and no matter whether he lea\'es the root filling 
 operation to some other operator, or does it himself, he could not 
 and would not dispense with the insurance of the perfection of 
 root fillings, as is furnished to him by no other available means 
 than the .r-ray. Like obscure chronic dental abscesses, unfilled Oi- 
 imperfectly-filled root canals are a prolific source of systemic 
 infection, in fact a large percentage of chronic blind abscesses are 
 directly caused by imperfect root-canal work, the infection being 
 set up by the hematogenous route. Various stages and conditions 
 of root canal fillings are illustrated in Figs. 703 to 710. 
 
 Perforations (see Figs. 707 to 713), accidentally produced in efforts 
 at enlarging or opening root canals especially in cases of extensive 
 calcification or formation of secondary dentin, or the presence of 
 foreign bodies such as fragments of broaches, reamers, burs, etc., in 
 root canals or in the periapical space, cannot escape detection if the 
 safet^' measure of .r-ra^' examination is resorted to before instituting 
 
IXDICATIOXS FOR THE USE OF RONTGENOGRAMS 431 
 
 restorations, and the necessity of such timely detection will surely 
 not be challeuijed l)\' any operator. 
 
 Fig. 703. — Successful effort in open- 
 ing two very small canals to the apex 
 in upper second liicuspid. 
 
 Fi(i. 704. — Successful filling oi canals. 
 
 I'lc. 705. — Imperfect root ca,nal fill- 
 ings, alveolar abscesse.s and root re- 
 maining in jaw. 
 
 Fig. 706. — Filling of root canals and 
 accidental crowding of filling material 
 through ai)ex. This ai)parently wis 
 non-irritating and gave the patient no 
 trouble. 
 
 Fk;. 707.— Succe.ssfui opening of calci- 
 fied canals with wire inserted to apex. 
 .M.so -iucccssful opening of pulp chamber 
 giving a clear field of vi.sion U> canals .so 
 essential in Hucce.ssful root canal work. 
 Menial canal successfully filled. 
 
 l'"ii;. 70^.— Perfect root-canal fillint 
 and perforation. 
 
 Roots. Fificf)irf'(l lioot.s. 1 nder the .stress ol' mastication or as 
 the result of trauma, the root of a tooth may have l)cen fractured. 
 
432 RADIOGRAPHY IN CROWN AND BRIDGE-WORK 
 
 Usually the presence of such a fracture is readily detected by the 
 patient, but for the operator it is of great value to determine the 
 
 Fig. 709. — Overfilled and perfor- 
 ated roots, unfilled root, abscess and 
 root absorption. 
 
 Fig. 710. — Three perfect, one imperfect 
 root-canal fillings. 
 
 Fig. 711. — First molar showing perfor- 
 ated root with futile effort to fill canal. 
 Wires inside second molar showing com- 
 plete opening to apex. 
 
 Fig. 712. — Root perforation. 
 
 Fig. 713. — Shows broaches placed in perforations in floor of pulp chamber, mis- 
 taken for canals by the operator. These perforations were sealed after being located 
 by broaches and tooth filled. 
 
 extent and nature of such a fracture, if he wishes to prevent the 
 loss of the root which may be extremely valuable as an abutment 
 (see Fig. 714). 
 
INDICATIONS FOR THE USE OF RONTGENOGRAMS 433 
 
 Measuring Roofs. — -The length of the roots of teeth to be employed 
 as abutments, especially if a post is to be inserted in the root canal, 
 can be readily determined by a correctly-posed rontgenograph. 
 An accurate knowledge of this important datum naturally greatly 
 
 Fig. 714. — Shows frac- 
 tured root of central incisor, 
 result of traumatism. 
 
 Fig. 715. — Demonstrating the plan of introduc- 
 ing wires in canals of lower teeth and the correct 
 position for making exposure. 
 
 Fig. 716. — Abscess of 
 l<jwer centrals, the cor- 
 rect position and possi- 
 bility of showing normal 
 longth of lower teeth, 
 and lack of root-canal 
 filling'. 
 
 Fig. 717. — ^Wires inserted in 
 root canals for measuring pur- 
 poses. 
 
 Fig. 718.— Wire in- 
 serted in root canal for 
 purposes of diagnosis. 
 
 facihtates the operator's task in determining Jiot only the length 
 of tlie po.st which he may insert, but also the limit of stress and 
 strain which lie may impose upon a particular abutment. The 
 method of taking accurate measurement of the length of a root, by 
 means of wires inserted therein, is illustrated in Figs. 715 to 718. 
 2S 
 
434 
 
 RADIOGRAPHY IN CROWN AND BRIDGE-WORK 
 
 Anomalies in the Number of Roots. — Although he be thoroughly 
 familiar with special dental anatomy, the crown and bridge worker 
 may be uncertain as to the number of roots present in a particular 
 tooth, since deviations from the normal number of roots are met 
 with quite frequently. Failure to detect the presence of such an 
 anomaly in a patient would naturally lead, sooner or later, to 
 complications, the nature of which would remain obscure to the 
 patient as well as the operator, were ' it not for radiographic 
 evidence (see Figs. 719 and 720). 
 
 Fig. 719. — Lower double-rooted 
 cuspid, showing the possibility of 
 failure by following the usual rule 
 of looking for one canal in anterior 
 teeth. Such multiple canals are 
 often seen by the radiographer. 
 
 Fig. 720. 
 
 -Lower first molar with three 
 root canals. 
 
 Anomalies in the Shape and Direction of Roots. — Curved, crooked, 
 constricted or flattened roots present special difficulties to the 
 crown and bridge worker. The torsion of a root may even be so 
 pronounced as to entirely preclude the possibility of successful root- 
 canal filling, and it would be nothing short of folly to attempt the 
 placement of a restoration upon such an unreliable foundation. 
 The general direction of roots and their parallelism, so important 
 in bridge restorations, is quickly determined by radiographs, as 
 shown in Figs. 721 and 722. 
 
 Proximity of Roots to the Maxillary Sinns.—1\\e proximity of 
 roots to the maxillary sinus may be a factor in determining what 
 amount of stress may be safely imposed upon an abutment. In 
 case of protrusion of a root into the sinus itself, it is, of course, 
 essential that the operator be aware of this fortunately rare con- 
 dition, and be guided accordingly in his operative procedures (see 
 Figs. 723 and 724). Disease of the maxillary sinus, if suspected. 
 
IXDICATIOXS FOR THE USE OF RONTGENOGRAMS 435 
 
 shoiikl be fully ascertained before any steps are taken toward 
 crown or bridge restoration, since the pathok^gical condition could 
 only be seriously aggravated by untimely and ill-advised prosthetic 
 interference. 
 
 Fig. 721. — Crooked root of lower 
 .•second bicuspid demonstrating the im- 
 possilnlitj' of successful root filling. 
 First molar shows enlarged tooth roots 
 with calcified canals. 
 
 Fn;. 722. — Crooked roots of a lower 
 second molar with alveolar border de- 
 stroj-ed by pj-orrhea. 
 
 Root Fmgtiients Left in the Mouth. — It goes without saying that 
 the presence of a root fragment left in the alveolar process 
 (see Figs. 725 and 726) would seriously jeopard the usefulness and 
 service of a bridge, since an acute infection ma\' at an>' time be 
 .set up around such a fragment as a nucleus. The .r-ra\' readily 
 re\eals tli(^ presence of any such fragments, and their extraction 
 
 Fit;. 72'-i. — Six teeth on small film and 
 position for making exposure. .\lve()lar 
 iib«ces.s and unfilled canal of .second bi- 
 cuspid. Large area above molar.s shows 
 •lipping down of lower Ijorder <>! maxiUnn/ 
 xinuK, but (loos n<it indicate any special 
 p:ttho|r>gical crmdition. 
 
 l'"i<;. 724. — Upper teeth, abscesses 
 and unfilled canals, rarefied area 
 extending from lateral to first molar. 
 The light area extending over bicus- 
 ))ifl and molar is the anterinr liorder 
 of the maxillary sin\is. 
 
 becomes a inatt<'r of course bcfon" attemptiug prosthesis, since 
 llic removal of dcepl.x- iuibcddf*! I'oot fragmeuts from under a 
 bri<lge offers uiiiieeessjiry eom|)li(ii( ions, mikI miglil result in flie 
 (lestruetion of the bridge by the exodontist. 
 
436 RADIOGRAPHY IN CROWN AND BRIDGE-WORK 
 
 Pyorrhea Alveolaris. — Next to dental caries, the disease, or 
 rather, the complex of diseases called pyorrhea alveolaris calls 
 
 Fig. 725. — Lateral root that re- 
 mained in the mouth ten years after 
 effort at extraction. 
 
 Fig. 726. — Later effort which re- 
 sulted in pushing the root in the alveo- 
 lar region at the floor of the nose. 
 
 Fig. 727. — Portion of first bicuspid apex 
 located in necrotic area in immediate proximity 
 to the wall of the maxillary sinus. 
 
 Fig. 728. — Pyorrheal teeth and 
 normal position for making radio- 
 graph of lower incisors. 
 
 Fig. 729. — Pyorrheal teeth, and 
 complete destruction of alveolar 
 support. 
 
 Fig. 730. — Ill-fitting crown placed over 
 tooth with broken broach left in root canal. 
 
IXDICATIOXS FOR THE USE OF RONTGENOGRAMS 437 
 
 most frequently for prosthetic restoration of the masticating 
 organs. After thorough surgical ciu-etmeut and therai)eutic and 
 dietetic measures have been instituted by the pyorrhea specialist, 
 the crown and bridge worker may be called upon to afford the 
 patient's teeth surgical rest in the form of immobilization b>' means 
 of a temporary splint. As soon as consolidation of the affected 
 teeth lias taken place, his plans naturally turn to permanent restora- 
 tion, the jjracticability of which is again determined by the radio- 
 graphic findings. It would be folly to base any reconstructional 
 work upon weak and unreliable abutments which are supported 
 by but a doubtfully strong, worse by an almost completely destroyed 
 ah-eolus, as shown in Figs. 728 and 729. The radiograph will 
 be the final criterion as to the retention or elimination of doubtful 
 links in the chain of abutments; it will militate against unwise 
 hyperconservatism, and safeguard an honest prognosis. 
 
 Fig. 7.31. — Steel needle broken during tuberositj- injection. 
 
 Foreign Bodies. — Fortunately, the presence of foreign bodies in 
 the ma.xilla' usually manifests itself by a violent reaction; yet in 
 persons of low vitality whose defensive force is greatly reduced, a 
 foreign body may be tolerated by the tissues for a surprisingly 
 prolonged period of time. Broken broaches, })robes, burs, reamers, 
 drills, etc., may remain in root canals without signaling their 
 presence by inflammatory reaction, and the placement of a crown 
 over such a tooth may cast a serious reflexion upon the crown 
 aiifl bridge worker's circumspection (.see Fig. 730). An excessive 
 amount of gutta-p<'rcha or resin may have been forced through the 
 ajMcal foramen into the peria[)ical space in an attempt to fill a root 
 canal to the end, and tliougli it may be lying dormant for awhile, 
 it will surel\' sometime sooner or later manifest its presence by a 
 violent inflammation. Here again, the .r-ray discloses the location 
 and amount ui foreign material and gnidcs tlic surgeon's hands in 
 its removal by way (»f ahcolotomy. 
 
438 RADIOGRAPHY IN CROWN AND BRIDGE-WORK 
 
 As conductive anesthesia is daily growing in popularity, and since 
 the use of steel needles, despite numerous contra-indications, is 
 still being persisted in by many operators, the number of instances 
 in which needles are fractured within the tissues is bound to increase. 
 If sterile, these needles may cause no disturbance whatever for some 
 time, yet any decrease in the resistance of the area in question 
 may lead to complications which may prove fatal to the crown and 
 bridge worker's achievement. Radiographic search, therefore, for 
 fractured steel needles is indicated whenever there is the slightest 
 suspicion of such an accident having occurred, and the fragment is 
 to be removed by surgical intervention. A case of this description 
 is illustrated in Fig. 731. 
 
 ILL-FITTING CROWNS AND BRIDGES AND THEIR 
 SEQUELS. 
 
 After what has already been said about the untoward sequelae of 
 ill-fitting crowns and bridges, it seems hardly necessary to empha- 
 size once more the multiple dangers that may lurk in poorly con- 
 structed work for the preservation of the abutment units as well as 
 the oral and general health of the patient. Since the question has 
 been seriously asked : "Is crown and bridge-work a menace?", it 
 behooves the specialist to justify his answer: "Not, if constructed 
 with due consideration of the principles of mechanics, anatomy, 
 physiology and pathology of the units involved," by a judicious 
 and liberal application of all the means available for the preclusion 
 of failure, and toward this end, the .r-ray has surely proved itself 
 to be an indispensable adjuvant. The illustrations presented in 
 Figs. 732 to 737 are shocking negative examples of bridge-work, 
 and their correct interpretation and explanation to the patient 
 will in many cases result in the patient's realization of the necessity 
 of the elimination of the pathologic conditions present and in his 
 consent to a reconstruction of the prosthetic work upon truly 
 scientific principles after removal of the old menace and restoration 
 of the tissues to full health. A series of radiographs encompassing 
 the full upper and lower arches will afford the best survey over the 
 condition of a mouth. A striking example of this sort is furnished 
 in Figs. 738 to 745. The patient, a well-knoM^n physician and 
 writer on general and, since the revelation of his own deplorable 
 dental condition, oral prophylaxis, claimed to have a perfectly 
 "comfortable" mouth, while systemically he was suffering with 
 
ILL-FITTING CROWNS AND BRIDGES 
 
 439 
 
 rheumatoid arthritis associated with septic endocarditis. A 
 radiographic examination of his mouth revealed tiie following 
 conditions: 
 
 Fig. 732. — Ill-fitting bicuspid orown. 
 hyperrementosed root, and alveolar 
 abscess. 
 
 Fig. 734. — Alveolar abscess. Two 
 overhanging dummies on bridge. Ill- 
 fitting crown on bicuspid . 
 
 Fig. 7.3.'^. — Lower first molar, with 
 both roots abscessed. Anterior root 
 bathed in pus. Extensive destruction 
 of process. Posterior root shows caries 
 under crown. 
 
 Fi(i. 7.3.5. — Large abscess sack at root 
 of bicuspid imder bridge, and ill-fitting 
 crown. 
 
 I'"i<;. 7.'iG. — ^Biou.s|>ifi with apical abscess Fig. 7.37. — Large abscess area pro- 
 
 and ill-fitting l)icuHpid and mf)lar crowns. <hiced by death of pulp under ill-fit- 
 
 ting i)i(Mispid ciowii. 
 
 Fig. 738: Claries hcricath filling; alveolar abscess draining into 
 intcnlcntal space; absence of root c-anal fillings in fir.st, second, and 
 thini molars. 
 
440 RADIOGRAPHY IN CROWN AND BRIDGE-WORK 
 
 Fig. 739:] Imperfect root-canal fillings in bicuspid and cuspid, 
 with calcification of unfillecj portions; poorly fitting band. 
 
 Fig. 738 
 
 Fig. 7;j9 
 
 Fig. 740 
 
 Fig. 741 
 
 Fig. 742 
 
 Fig. 743 
 
 Fig. 744 
 
 Fig. 745 
 
ILL-FITTIXG CROWNS AND BRIDGES 
 
 441 
 
 Fig. 746 
 
 Fio. 747 
 
 Fi<;. 748 
 
 Fig. 749 
 
 Fir;. 750 
 
 Fig. 751 
 
 Fia. 752 
 
442 RADIOGRAPHY IN CROWN AND BRIDGE-WORK 
 
 Fig. 740: Crooked third molar roots. 
 
 Fig. 741 : Similar conditions as in Figs. 738 to 740. 
 
 Figs. 742 to 745: General septic and rarefied areas involving 
 apices of roots; syndrome of untoward mechanical and pathologic 
 conditions. , 
 
 Thorough corrective treatment, beginning with the removal of 
 the "septic" crown and bridge-work, restitution of the tissues to 
 health, correct root-canal fillings and correctly constructed crown 
 and bridge-work restored the patient to health, the systemic 
 symptoms subsiding with the removal of the oral sepsis. 
 
 Another interesting example of a supposedly healthy mouth is 
 illustrated in Figs. 746 to 752. This patient was of normal appear- 
 ance and weight, and claimed health with the exception of rheu- 
 matism and slight diabetes. All efforts to locate the seat of this 
 trouble proved negative, until the mouth was examined. For 
 the sake of practice, the interpretation of this radiographic series 
 is left to the reader. In this case, the forceps seem to be indicated 
 as the best therapeutic agent for the restoration of the patient's 
 health. 
 
 Conclusion. — In conclusion, it may not be amiss to point out the 
 usefulness of which, from a medico-legal aspect, may be the .r-ray 
 in substantiating or disproving charges of malpractice brought 
 against the crown and bridge worker; for it is by this means that 
 the success of attempts at palliative treatment prior to insertion of 
 bridge-work, and the accuracy of bands, the paralielity of posts, 
 the perfection of root-canal fillings, in short almost all the factors 
 that constitute scientific bridge-work can be demonstrated ad 
 oculos. In teaching crown and bridge also, the radiograph is an 
 instructive and convincing aid in demonstrating poor versus good 
 bridge-work. 
 
 In fine, dentistry more than any other profession has, despite the 
 remarkably short period of time in which it has evolved from a 
 trade into an art and science, availed itself of every innovation in 
 the fields of technic and science in its arduous strife toward perfec- 
 tion. It therefore behooves the specialist in crown and bridge- 
 work, who is called upon to make the most skilful restorations 
 known in the realm of prosthesis, to avail himself to the fullest 
 extent of William Konrad Rohtgen's discovery. 
 
INDEX 
 
 Abscess, dento-alveolar, 25 
 acute, treatment of, 26 
 
 aromatic sulphuric aciti in, 27 
 peroxide of hydrogen in, 2() 
 danger of, 27 
 chronic, treatment of, 30 
 estabhshing fistula in, 28 
 locating apex of root in, 28 
 painless insertion of hypodermic 
 
 needle in, 29 
 r:idiogi-aphy and, 428 
 root amputation in, 31 
 fiUing canal in, 31 
 treatment of wound, 32 
 Aljutments for extension saddle 
 bridges, 314 
 inlay, 260. See Inlay abutments, 
 paralleling of, 207 
 
 Weinstein's device for, 208 
 with tube in mouth, 209 
 posterior, paralleling of, 210 
 preparatif)n of, 207 
 for removable bridges, paralleling of, 
 228 _ 
 retaining, 226, 227 
 supporting, 22ii, 227 
 sui)j)()rting, 272 
 
 gold fillings, cavity for, prepara- 
 tion of, 273 
 finishing of, 273 
 imi)ression for, 273 
 indications for, 272 
 inlay, 274 
 
 adjusting of, 275 
 
 casting of, 27") 
 
 (;avity for, pre|)aration of, 274 
 
 cementing ui, 27.') 
 
 completion of bri<lgi' with spur, 
 
 274 
 finishing fjf, 27.j 
 forming seat for spur, 275 
 location <;f po.sition on model for 
 
 st)ur, 274 
 maKirig of spur, 274 
 shai)ing of spur, 274 
 waxing of, 275 
 Alloys, binary, 360 
 
 Alloys, binary, comparative hardness 
 of, 371 
 melting points of, 368 
 of gold, compounding of, 383 
 
 and copper, melting points of, 
 
 364 
 and palladium, melting points of, 
 
 366 
 and platinum, melting jjoints of, 
 
 365 
 and silver, melting points of, 362 
 solders, 382 
 for making bantls, 164 
 new series of, 371 
 
 application of, in Peeso's system 
 of crown and bridge-work, 405 
 construction of bands with, 405 
 of dummies with, 407 
 of floors with, 405 
 of inlay abutments with, 406 
 of inner caps with, 405 
 of outer half bands with, 406 
 of saddles with, 407 
 of telescope crowns with, 406 
 melting points of, 405 
 for jjrosthetic castings, 374 
 Alveolar abscess, radiography and, 428 
 Amalgam, building-up broken down 
 
 roots with, 143 
 Ami)utation of root ends, 31 
 Anatomical articulators, 133 
 Anesthesia in devitalization of ])ulp, 41, 
 
 44 
 Anterior crowns, measurement of 
 stump for, 187 
 teeth, l)anded crowns for, 187 
 inlay iibutments for, 261 
 
 attiu^hing sy)rue wire in, 262 
 building inlay in wax with 
 
 tube in place, 262 
 canal for enlarging of, 261 
 casting of, 262 
 
 cavity of, finishing of, for 
 .s(!con(l inlay, 264 
 preparation of, for second 
 
 lay, 2()3 
 .shaping of, 261 
 filling |)ure gold m;itri\ with 
 (!oin gold, 266 
 
444 
 
 INDEX 
 
 Anterior teeth, inlay abutments for, 
 finishing of, 267 
 fitting tube with asbestos 
 
 paper in, 262 
 flasking of, 262 
 impression with inlay in place, 
 
 263 
 investing of, 266, 267 
 model for, preparation of, 263 
 polishing inlay in, 267 
 removal of tube with wax 
 
 inlay from mandrel, 262 
 second inlay in, making of, 
 
 265 
 soldering with bridge, 267 
 waxing of, 267 
 jacket crowns for, 197 
 lower, radiography of, position 
 
 for, 418 
 porcelain crowns for, 302 
 bite in, 302 
 
 casting bases on abutment 
 caps, 306 
 on small saddles, 306 
 copper drills in, 304 
 crowns in, 302 
 impressions in, 302 
 retaining wall in, 304 
 saddle in, adjusting of, 302 
 impression for, 302 
 making of, 302 
 shrinking of cast base on cool- 
 ing, 305 
 tin foil in, use of, 305 
 waxing bases to abutment 
 cap, 307 
 to saddle, 307 
 posts for, 307 
 pulp canals of, 52 
 removable attachments for, 251 
 adjusting band in, 251 
 broken facings in, cause of, 258 
 
 prevention of, 258 
 enlarging entrance to tube in, 
 
 254 
 facing roots in, 252 
 finishing caps in, 254 
 fitting band in, 251 
 
 split pin to tube and floor 
 
 of outer cap, 254 
 tubes in, 253 
 investing spht pin in floor, 255 
 making half-band, 256 
 soldering half-band to floor, 
 256 
 split pin in floor, 255 
 tubes in, 253 
 sweating floor in, 252 
 trimming outer floor to inner 
 cap, 256 
 upper, radiography of, position 
 for, 417 
 
 Arsenic in devitalization of pulp, 38 
 Articulating plates, 138 
 
 surfaces, direction of, 139 
 Articulators, 133 
 anatomical, 133 
 
 with face bow, 134 
 crown, 133 
 plaster, 135 
 making of, 135 
 Artificial stone, Weinstein's, 120 
 
 impressions with, filling of, 121 
 preparation of, 121 
 separation of, 122 
 mixing of, 121 
 Autogenous soldering, 159 
 
 B 
 
 Band, sweating of floors to, 189 
 
 uniting of cusp to, 185 
 Banded crowns for anterior teeth, 187 
 Bands, construction of, new series of 
 alloys and, 405 
 contouring of, 178 
 fitting of, to anterior crowns, 188 
 to roots broken below gum line, 
 145 
 decayed below gum line, 145 
 making of, alloys suitable for, 164 
 lapped joint vs. abutted joint, 161 
 technic of, 162 
 outer half, construction of, new series 
 
 of alloys and, 406 
 in removable attachment for anterior 
 teeth, adjusting of, 251 
 fitting of, 251 
 shaping of, use of collar pliers in, 
 
 175 
 soldered joint, 164 
 sweating of, with blow pipe, 163 
 
 with Bunsen flame, 163 
 trimming of teeth for, 82 
 waxing in of, in impressions, 127 
 Bicuspids, jacket crowns for, 199 
 lower, cusps of, 172 
 pulp canals of, 52 
 trimming of, 96 
 radiography of, position for, 419 
 upper, first, placing pin in, 190 
 pulp canals of, 51 
 trimming of, 101 
 Binary alloys, 360 
 
 comparative hardness of, 371 
 melting points of, 368 
 Bite in porcelain crowns for anterior 
 teeth, 302 
 proper closure in, securing of, 125 
 in saddle bridges with abutments at 
 both ends, 335 
 Bridge-work, gold for, 372 
 object of, 205 
 
INDEX 
 
 445 
 
 Bridges, dental, 205 
 
 abutments for, paralleling of, 207 
 Weinstein's devise for, 208 
 with tube in mouth, 209 
 posterior, paralleling of, on 
 
 model, 210 
 preparation of, 207 
 classification of, 205 
 extension, 220 I 
 
 l)icuspids, 220 
 
 rule regarding supports for, 221 
 small anterior, 220 
 with saddles, 221 
 fixed, 206, 215 
 
 anterior, backing of, 218 
 grinding of, 218 
 interchangeable facings and, 
 finishing of, 219 
 grinding duplicates, 220 
 investing for soldering, 218 
 cementing of, 337 
 
 bleeding gums and, 338 
 cleansing before, 337 
 drying field of operation in, 
 338 
 out roots in, 338 
 mixing cement, 338 
 placing cement in canals, 338 
 removal of excess cement, 338 
 common type of, 216 
 cusps for, grinding of, 217 
 
 selecticm of, 217 
 facings for, backing of, 21() 
 grinding of, 2 Hi 
 selection of, 216 
 porcelain crowns with soldered 
 base in, 221 
 fitting bases, 222 
 grinding of, 222 
 investing of, 223 
 j)lacing i)osts in, 222 
 soldering jjosts in, 222 
 posterior, investing of, 217 
 
 waxing-up of, 217 
 soldering in sections, 218 
 large, divided, 75 
 
 one piece, 75 
 occluding with plate, 73 
 occlusion and, 21 1 
 jKjrcelain, 151 
 nmiovable, 200, 225 
 
 abut ments for i)arall(!ling of, 228 
 retaining, 22(1, 227 
 su|)portirig, 226, 227 
 advantages of, ov(t fixeil 
 
 bridges, 225 
 for anterior tcetli, 251 
 altaclitnenis for, 226 
 (;enienting of, 339 
 l)ridge in inoutli, '.V-iU 
 cleansing bcrfore, '■>'-'>U 
 inluyH for, 339 
 
 Bridges, dental, removable, cementing 
 of inlays for, cement 
 syringe in, 340 
 cleansing of, 340 
 removal of excess cement, 339 
 
 of wax, 339 
 waxing preparatory to, 339 
 inlay abutments in, 260. See 
 
 Inlay abutments, 
 key and shoe attachment, 250. 
 
 See Key and shoe, 
 porcelain crown with cast base, 
 
 301. See Crown porcelain, 
 split pins for, 284 
 telescope crowns in, 227 
 value of, accuracy and, 22() 
 requisites for, 206 
 supports, 74 
 
 tubes for, 276. See Tubes. 
 Bryant's system of replacing broken 
 facings, 350 
 
 Canals, pulp. See Pulp canals. 
 
 Cap, inner, construction of, new series 
 
 of alloys and, 405 
 Caps trimming of teeth for, 82 
 
 waxing in of, in impressions, 127 
 Caries, dental, radiography and, 425 
 Carmine solution, preparation of, 123 
 Casting, fluxes for, 400 
 
 investment compounds for, 392 
 formula for, 396 
 hot or cold moulds in, 394, 395 
 process, all porcelain crowns with 
 cast base, 200 
 grinding of crowns in, 201 
 root preparation in, 200 
 selection of crowns in, 201 
 wax base, casting of, 201 
 flasking of, 201 
 availability of, in crown work, 199 
 banded crowns, 201 
 casting of, 202 
 flasking of, 202 
 porcelain facings, 202 
 waxing of, 202 
 casting flirectly on facings, 204 
 drying out flask in, 204 
 facings nsinovcid and cemented 
 
 after casting is made, 203 
 heating flask in, 204 
 Coastings, iiflay, gold for, 375 
 formula for, 377 
 prosthetic, gol<l for, 371 
 (,'em(Mit syringe, 340 
 Ceiiicnting lixed bridgcis, 337. jS'ee 
 liridgcs, fix('d, ci'iiKMiting of. 
 ol inlay abutments for molars, 270 
 for removable bridg(!S, 339 
 
446 
 
 INDEX 
 
 Cementing of removable bridges, 339. 
 See Bridges, removable, cementing \ 
 of. 
 Clasp metals, 378 
 
 composition of, 379 
 melting point of, 379 ! 
 
 Clasp-wire split pins, 285 
 Cleavers, enamel, 118 
 Cologne solution, preparation of, 123 
 Contouring of bands, 178 
 
 pliers, 160 
 Copper, alloys of, melting points of, 363 
 Crown articulators, 133 
 
 setter, 343 
 Crowning of broken-down roots, 143 
 Crowns, anterior, fitting bands to, 188 
 measurement of stump for, 187 
 banded, for anterior teeth, 187 
 casting process in, 201 
 porcelain facings, casting process 
 in, 202 
 casting process in, availability of, 199 
 combination, 241 | 
 
 construction of, 241 j 
 
 contraction of tubes on soldering, 
 
 247 
 countersinking entrance of tube, 
 247 ; 
 
 ,' cusps of, adjusting of, 248 
 
 fitting of, 248 | 
 
 investing of, 249 I 
 
 preparation of, 248 
 selecting of, 248 j 
 
 soldering of, to cap, 249 ■ 
 
 enlarging necks, for split pins, 247 
 fitting split pins in tubes, 247 
 
 tube in, 243 
 impression for, 242 
 inner cap of, making of, 243 
 investing of, 244 
 outer cap of, making of, 245 
 soldering split pin in outer cap, 248 
 in tube, 244 
 cutting band, sweating, and fitting 
 
 band to stump, 174 
 for deeply decayed teeth, making of, 
 
 150 
 Downey, 195 
 investing of, 196 
 soldering of, 196 
 gold for, 372 
 
 built-up solid cusp, 173 
 
 making of, technic of, 174 
 h'alf caps, 197 
 jacket, 197 
 
 for anterior teeth, 197 
 for bicuspids, 199 j 
 
 porcelain, 195 ! 
 
 for anterior teeth, 302 
 bite in, 302 
 
 casting bases on abutment 
 caps, 306 
 
 Crowns, porcelain, for anterior teeth, 
 casting bases on small 
 saddles, 306 
 copper drills in, 304 
 crowns in, 302 
 
 bases, making of, 303 
 grinding of, 302 
 impression in, 302 
 retaining wall in, 304 
 saddle in, adjusting of, 302 
 impression for, 302 
 making of, 302 
 shrinking of cast bases on 
 
 cooling, 305 
 tin foil in, use of, 305 
 waxing bases to ' abutment 
 caps, 307 
 to saddle, 307 
 posts for, 307 
 application of, 301 
 casting process in, 301 
 deep saddle, 309 
 
 bases for, casting of, 309 
 investing of, 311 
 ring, casting of, 310 
 soldering to cap, 311 
 
 to saddle, 311 
 uniting of, 310 
 waxing of, to cap, 310 
 to saddle, 310 
 carving sides for plates, 311 
 cementing crowns in place, 313 
 finishing of, 313 
 grinding of, 309 
 impressions for, 312 
 models for, 312 
 wall to hold crown in place, 309 
 waxing sides for plates, 311 
 depth of bite for, 301 
 faced, 187 
 
 as abutments for extension sad- 
 dle bridges, 314 
 backing of, 192 
 finishing of, 195 
 single, investment for, 194 
 soldering of, 192, 194 
 waxing-up of, 192 
 spatula for, 194 
 investing of, 196 
 limitations of, 301 
 selection of, 214 
 shade variation and blending of, 
 
 214 
 shapes of, 215 
 soldering of, 196 
 top, as abutments for extension 
 
 saddle bridges, 314 
 types of, 215 
 with cast base, casting process in, 
 
 200 
 with soldered base in fixed bridges, 
 221 
 
IXDEX 
 
 447 
 
 Crowns, porcelain, witli wax l)ase, 
 casting process in, 201 
 re|)airing of, 342 
 crown setter in, 343 
 removal of caj> for porcelain or 
 jrorcelain-faced crown, 345 
 of i)o.st, 345 
 
 ])ost-pxiller in, 345 
 with drill and pliers, 345 
 shell crowns, 343 
 replacing facings, 346 
 soldering facings, 346 
 Ivichmond, 187 
 l)acking of, 192 
 finishing of, 195 
 single, investment for, 194 
 soldering of, 192, 194 
 waxing up of, 192 
 spatula for, 194 
 seamless, 165 
 
 instability of, 166 
 setting of, with gutta-percha, 341 
 with oxyphosphate of zinc, 336 
 shell, repairing of, 342-344 
 taking measurement of stump for, 
 
 173 
 telescope, 227 
 as abutments for extension saddle 
 
 bridges, 314 
 alloys for, 227 
 
 Weinstein's, 22H,')iote. 
 construction of, new series of 
 
 alloys and, 406 
 contour of, casting of, 240 
 cusps of, casting of, 240 
 preparation of, 238 
 .selection of, 238 
 soldering of, 2.39 
 durabilit}' of, 228 
 inner cap of, cutting bands for, 229 
 fitting bands to .stump, 229 
 nicasurcnient of, 229 
 polishing of, 231 
 reinforcing of, 231 
 sweating floor to, 230 
 outer cap of, burnishing of, 235 
 contour of, 236 
 
 restoring of molars to, 237 
 .shaping of, 237 
 soldering of, 237 
 liquid flux for, 236 
 finishing of, 240 
 fitting over inner, 2.34 
 making of, 233 
 measureuK'nt of, 233 
 oj'chjsal end of, filling of, 235 
 
 filing of, 235 
 removal of, from inner, 235 
 sweating floor to, 2;{6 
 trimming of, 23(i 
 trr(;liiiir- of, 228 
 trimming tooth for, 228 
 
 Crowns, telescope, with tube arul split 
 pins, 241. See Crowns, combina- 
 tion, 
 window, 197 
 
 with cast bases, attaching sj)rue wire, 
 224 
 posterior, 223 
 use of, 223 
 
 waxing l)ases for casting, 223 
 Cusp buttons, making of, 180 
 
 holding and filling base of, 184-185 
 matrix, filling of, with coin gold, 183 
 
 swaging devise for, 182 
 uniting of, to l)and, 185 
 Cuspids, radiosrraphv of, position for, 
 
 415 
 Cusps for extension saddle Ijridges, 
 fitting of, 324 
 trimming of, 325 
 for fixed bridges, grinding of, 217 
 
 .selection of, 217 
 of lower bicuspids, 169, 172 
 molars, first, 171 
 second, 172 
 third, 172 
 making of, 179 
 
 of telescope crowns, preparation of, 
 238 
 selection of, 238 
 .soldering of, 239 
 of upper bicuspids, 169, 172 
 molars, first, 169 
 second, 1()9 
 third, 170 
 
 De.nsitv of metals, table of, .359 
 Dental bridge, 205. See Bridger, den 
 tal. 
 caries, radiograjjiiy and, 425 
 metallurgy, 357 
 Dentimeter, Kirk's, for mea.sinement 
 
 of roots, 187 
 Dento-alveolar abscess, 25 
 acute, treatment of, 26 
 
 arom, tic sulphuric acid in, 27 
 peroxide of hyflrogen in, 26 
 danger of, 27 
 chronic, treatment of, 30 
 establishing fistula in, 28 
 locating apex of root in, 28 
 painless in.sertion of hyi)odermic 
 
 needle in, 29 
 root amputation in, .31 
 filling caiia.l in, 31 
 treatment of wound in, 32 
 l)c\ it.ilizatioii of |)ulp, '■'>'■'> 
 .'igents u.sed in, 3(i 
 .•irsenic in, ,38 
 flangei' of, 39 
 
448 
 
 INDEX 
 
 Devitalization of pulp, discoloring of 
 teeth after, cause of, 34 
 prevention of, 34 
 
 Dr. Herman Prinz's method, 36 
 
 exceptions to, 33 
 
 heroic method of, 39 
 
 local anesthesia in, 44 
 
 novocaine in, 44 
 
 pressure anesthesia in, 41 
 
 sterilization of field of operation 
 in, 42 
 
 treatment preparatory to, 41 
 Donaldson's canal cleaners, 54 
 Downey crowns, 195 
 
 enlarging pulp canals for, 61 
 
 investing of, 196 
 
 root facings for, 113 
 
 soldering of, 196 
 Drawn tubes, 276 
 Drilled tubes, 276 
 
 E 
 
 Elongation of teeth from lack of 
 
 occlusion, 213 
 Enamel cleavers, 118 
 
 scalers, 103 
 Evans' root drier, 338 
 Extension bridges, 220 
 bicuspids, 220 
 
 rule regarding supports for, 221 
 small anterior, 220 
 with saddles, 221 
 saddle bridges, 314 
 
 abutments necessary for, 314 
 porcelain-faced crowns, 314 
 
 top crowns, 314 
 telescope crowns, 314 
 adjustment of, saddle to abut- 
 ments, 318 
 to ridge, 314, 317 
 buccal plates, carving for, 325 
 clamping to saddle, 328 
 impressions for, 326 
 investing of, 329 
 models for, 326 
 soldering of, 329 
 waxing for, 325 
 contraction of gold in soldering, 
 and restoring of proper align- 
 ment, 321 
 cusps of, fitting of, 324 
 
 trimming of, 325 
 facings for, backing of, 324 
 bevelling of, 324 
 grinding of, 323 
 selection of, 323 
 with gold occlusal surfaces, 
 use of, 323 
 finishing of, 333 
 
 Extension saddle bridges, fusible meta 
 counterdies for, making 
 of, 327 
 dies for, making of, 327 
 grinding of, 333 
 impression for, 315 
 investing of, 320 
 
 for final soldering, 330 
 lingual plates, carving for, 325 
 impressions for, 326 
 models for, 326 
 soldering of, 331 
 
 of bridge and, 329 
 waxing for, 325 
 metal for, 316 
 
 cleansing of, 316 
 model for, 315 
 
 preparations of, 321 
 polishing of, 334 
 reinforcing of, 316 
 soldering to abutment caps, 320 
 body to bridge, 330 
 cleansing after, 332 
 drying after, 332 
 trimming and waxing to abut- 
 ment caps, 320 
 vulcanite attachment for, 322 
 
 Facings, broken, replacing of, 342 
 bending pins in, 346 
 on bridge without removal from 
 
 mouth, 346 
 Bryant system of, 350 
 cementing facings in place, 346, 
 
 348, 350 
 on crowns without removal from 
 
 mouth, 346 
 cutting out and dovetailing hole 
 
 in backs, 346 
 dovetailing holes in facing, 349 
 drilling out pins, carborundum 
 in, 348 
 glycerin in, 348 
 instruments for, 348 
 fitting tin backing to facing, 347 
 headed pins left in metal back- 
 ing in, 348 
 Peeso's method of, 346 
 for extension saddle bridges, 323 
 for fixed bridges, backing of, 216 
 grinding of, 216 
 selection of, 216 
 interchangeable, 218 
 backing of, 219 
 fixed bridges and, finishing of, 219 
 
 grinding duplicates, 220 
 investing of, 219 
 soldering of, 219 
 selection of, 214 
 
INDEX 
 
 449 
 
 Facings, shade variation and blending 
 of, 214 
 shapes of, 215 
 tj'pes of, 215 
 Files, proper use of, 176 
 Fixed bridges, 206, 215 
 
 anterior, backing of, 218 
 
 interchangeable facings and, fin- 
 ishing of, 219 
 grinding duplicates, 220 
 common type of, 216 
 cusps for, grinding of, 217 
 
 selection of, 217 
 facings for, backing of, 216 
 grinding of, 216 
 selection of, 216 
 posterior, investing of, 217 
 waxing-up of, 217 
 Floors, construction of, new series of 
 alloj-s and, 405 
 drilling of, for post or pin, 189 
 flattening of, swaging devise for, 188 
 sweating of, to band, 189 
 Fluxes, 400 
 
 for casting, 400 ' 
 oxidizing of, 403 
 
 formula for, 403 
 reduction of, 402 
 
 formula for, 402 
 for soldering, 400 
 
 formula for, 401, 404 
 Formalin in treatment of putrescent 
 
 pulp canals, 24 
 Fractured roots, treatment of, 68 
 Fusible metal, 232 
 
 dies and counterdies for extension 
 saddle bridges, 327 
 
 Gates-Glydden nerve canal drills, 58 
 Gold, alloys, compounding of, 3S3 
 
 melting points of, 362, 363, 364 
 for bridge-work, 372 
 cleansing of, 163 
 
 hydrochloric acid in, 163 
 
 saturated solution of alum in, 163 
 
 sulphuric acid in, 163 
 coin, fining cusp matrix with, 183 
 copper alloy and, 165 
 for crowns, 372 
 deoxidizing of, 163 
 for inlay casting, 375 
 formula for, 377 
 iridium alloys and, 360 
 osmium alloys and, 300 
 palladium alloys and, 366 
 
 f)latinized, spUt pins of, 285 
 or i)late work, 372 
 platinum alloys and, 364 
 rhodium alloys and, 370 
 
 29 
 
 Gold, silver alloy and, 165, 360 
 solders, 381 
 
 alloys for, 382 
 U. S. coin, 165 
 caret of, 228 
 properties of, 228 
 Gums, protection of stumps from en- 
 croachment of, 126 
 Gutta-percha points in filling pulp 
 canals, 62 
 setting of crowns with, 341 
 technic of, 341 
 
 Half caps or crowns, 197 
 
 round wke split pins, 284 
 Hammer-headed hand-vise, 278 
 Heroic method of devitahzing pulp, 39 
 Hydrochloric acid, use of, in cleansing 
 
 gold, 163 
 
 Impacted teeth, radiography and, 426 
 Imperfectly formed teeth, radiography 
 
 and, 426 
 Impressions, 120 
 
 and model, separating of, 140 
 
 and articulation with face bow, 134 
 
 artificial stone, Weinstein's, 120 
 
 bite and, 122 
 
 of broken-down roots, taking of, 144 
 
 teeth, taking of, 144 
 plaster, 120 
 
 of Paris, coloring of, 123 
 
 carmine solution, preparation 
 of, 123 
 flavoring of, 123 
 
 cologne solution, preparation 
 of, 123 
 mixing of, 124 
 removal of, from mouth, 126 
 in sections, 129 
 
 dovetailed spaces in, 132 
 of lower anterior teeth, 130 
 of teeth lingually inclined, 131 
 undercuts in, 132 
 treatment of, 126 
 separating medium in, 128 
 tough adhesive wax in, 127 
 waxing in bands in, 127 
 
 in caps in, 127 
 with abutments in place, taking of, 
 125 
 Inlay abutments, 260 
 
 for anterior teeth, 261 
 
 attaching sprue wire in, 262 
 building inlay in wax with 
 
 tube in place, 262 
 casting of, 262 
 
450 
 
 INDEX 
 
 Inlay abutments for anterior teeth, 
 enlarging canal for, 261 
 filling pure gold matrix with 
 
 coin gold, 266 
 finishing of, 267 
 
 of cavity for second inlay, 
 . 264 
 fitting tube with asbestos 
 
 paper in, 262 
 flaskmg of, 262 
 impression with inlay in place, 
 
 283 
 investing of, 266, 267 
 poUshing inlay in, 267 
 preparation of cavity for sec- 
 ond inlay, 263 
 of model for, 263 
 removal of tube with wax 
 
 inlay from mandrel, 262 
 second inlay, making of, 265 
 shaping of cavity for, 261 
 soldering with bridge, 267 
 waxing of, 287 
 construction of, new series of 
 
 alloys and, 406 
 indications for, 260 
 matrix, 271 
 
 pure gold or platinum foil, 271 
 for molars, 267 
 
 cavity in, depth of, for tubes, 
 267 
 for final inlay, 270 
 preparation of, 267 
 cementing of, 270 
 final inlay in, 270 
 finishing of, 270 
 matrix in, casting of, 268 
 
 preparation of, for impression, 
 
 268 
 securing of, 268 
 model for, preparation of, 269 
 second inlay in, carving of, 269 
 casting of, 269 
 soldering of, to pure gold 
 
 matrix, 270 
 waxing of, 269 
 tube in, adjusting of, 269 
 parallehng of, 269 
 for removable bridges, cementing 
 
 of, 339 
 for small bridges, 271 
 where indicated, 272 
 Inner caps, construction of, new series 
 
 of alloys and, 405 
 Interchangeable facings, 218 
 
 anterior fixed bridges and, finish- 
 ing of, 219 
 grinding duplicates, 220 
 backing of, 219 
 investing of, 219 
 soldering of, 219 
 Investing of combination crowns, 244 
 
 Investing of Downey crowns, 196 
 of interchangeable facings, 219 
 of porcelain crowns, 196 
 Investment compounds for casting, 392 
 formula for, 396 
 hot or cold mould in, 394, 395 
 for soldering, 385 
 formula for, 391 
 materials, compounding of, 397 
 for single porcelain-faced crowns, 194 
 Investments, directions for uses of, 397 
 
 heating of, 398 
 Iridio-platinum tubes, 276 
 
 . wire split pins, 284 
 Iridium alloys, gold and, 369 
 Irregularities of teeth, slight, 152-153 
 treatment of, 152-158 
 
 Jacket crowns, 197 
 
 for anterior teeth, 197 
 
 for bicuspids, 199 
 Jaw, lower, teeth of, relative strength 
 
 of, 72 
 upper, teeth of, relative strength of, 
 
 72 
 
 Kerr broaches in opening of pulp 
 
 canals, 47 
 Key and shoe, attaching key to crown, 
 250 
 completion of shoe, 251 
 constructing bridge, 251 
 making of, 250 
 preparing crown for key, 250 
 Kirk's dentimeter, for measurement of 
 roots, 187 
 
 Lead box for protecting unexposed 
 radiograph films, 412 
 glass diaphragm for. use in radiog- 
 raphy, 411 
 Lower anterior roots, trimming of, 107 
 teeth, impressions of, in sections, 
 130 
 bicuspids, cusps of, 172 
 characteristics of, 169 
 pulp canals of, 52 
 trimming of, 96 
 jaw, teeth of, relative strength of, 72 
 molars, first, cusps of, 171 
 pulp canals of, 49 
 second, cusps of, 172 
 third, cusps of, 172 
 trimming of, 83, 94 
 
INDEX 
 
 451 
 
 M 
 
 Mandrel process of making tubes, 277 
 Matrix method of inlaj- abutments, 271 
 Maxillary sinus, radiography of, posi- 
 tions for, 416, 422 
 Melting points of binary alloys, 368 
 of clasp metals, 379 
 of gold and copper, 364 
 and palladium, 366 
 and platinum, 365 
 and sUver, 362 
 of metals, table of, 359 
 of new series of alloys, 405 
 of standard dental goods, 405 
 Metal, fusible, 232 
 Metallurgj^, dental, 357 
 Metals, clasp, 378 
 
 composition of, 379 
 melting point of, 379 
 densities of, table of, 359 
 melting points of, table of, 359 
 Models, 120 
 of broken-down roots, preparation of, 
 144 
 teeth, preparation of, 144 
 casting of, 138 
 
 for deeply decayed teeth, 149 
 for extension saddle bridges, 315 
 for inlay abutments for molars, 269 
 plaster, 120 
 
 making articulating surfaces, 138 
 of roots broken below gum line, pre- 
 paration of, 145 
 decaj-ed below gum line, prepara- 
 tion of, 145 
 working, drj^ing out of, 141 
 hardening of, 142 
 preparation of, 140 
 trimming of stumped, 141 
 Molars, impacted, radiography of, posi- 
 tion for, 420 
 inlay aljutments for, 267 
 
 cavity in, depth of, for tubes, 
 267 
 for final inlay, 270 
 I)reparation of, 267 
 ceinentiiig o!, 270 
 final inlay in, 270 
 finishing of, 270 
 matrix in, casting of, 268 
 
 preparation of, for impression, 
 
 268 
 securing of, 268 
 model for, preparation of, 269 
 KCcon<i inlay in, carving of, 269 
 casting of, 269 
 soldering of, to pure gold 
 
 matrix, 270 
 waxing of, 269 
 tul^ in, adjusting of, 269 
 paralleling of, 269 
 
 Molars, lower, first, cusps of, 171 
 pulp canals of, 49 
 second, cusps of, 172 
 third, cusps of, 172 
 tilted forward, trimming of, 94 
 trimming of, 83 
 
 instruments for, 84 
 
 principal cuts in, 89 
 upper, first, cusps of, 169 
 pulp canals of, 47 
 second, cusps of, 169 
 third, cusps of, 170 
 trimming of, 97 
 
 principal cuts in, 98 
 
 N 
 
 Necrosis, radiography and, 426 
 Novocaine in devitaUzation of pulp, 44 
 
 Occlusion, 211 
 
 teeth elongated from lack of, 213 
 Orthodontia and prosthodontia, rela- 
 tion of, 151 
 Osmium alloys, gold and, 369 
 Ottolengui's root facers, 118 
 Oxidizing of flux, 403 
 formula for, 403 
 Oxyphosphate of zinc, 336 
 
 cementing fixed bridges with, 337 
 characteristics of, 336 
 mixing of, 336 
 
 spatula for, 336 
 setting crowns with, 336 
 
 Palladium, alloys of, melting points of, 
 
 366 
 Pathological conditions, relation of, to 
 
 crown and bridge-work, 22 
 Peeso's method of repairing broken fac- 
 ings, 346 
 root reamer, 59 
 
 system of crown and bridge-work, 
 application of new scries of alloys 
 to 405 
 Perforated roots, treatment of, 66 
 Peroxide of hydrogen in treatment of 
 
 dento-alveolar abscess, 26 
 Pins, crown, soldering and cap, 192 
 Plaster articulators, 135 
 making of, 135 
 impressions, 120 
 models, 120 
 of Paris, coloring of, 1 23 
 
 carmine solution in, preparation 
 of, 123 
 flavoring of, 123 
 
452 
 
 INDEX 
 
 Plaster of Paris, flavoring of, cologne 
 solution in, preparation of, 123 
 properties of, 389 , 
 Plate for tubes, 278 
 Plates, articulating, 138 
 Plate work, gold for, 372 
 Platinized gold split pins, 285 
 Platinum, aUoys of, melting points of, 
 
 365 
 Pliers, collar, use of, in shaping bands, 
 175 
 contouring, 160 
 pin roughing and bending, 193 
 stretching, 160 
 Porcelain bridges, 151 
 crowns, 195 
 
 for anterior teeth, 302 
 bite in, 302 
 
 casting bases on abutment 
 caps, 308 
 on small saddles, 306 
 copper driUs in, 304 
 crown bases in, making of, 
 303 
 grinding of, 302. 
 impression in, 302 
 retaining wall in, 304 
 saddle in, adjusting of, 302 ■ 
 impression for, 302 
 making of, 302 
 shrinking of cast bases on 
 
 cooUng, 305 
 tin foil in, use of, 305 
 waxing bases to abutment 
 cap, 307 
 to saddle, 307 
 posts for, 307 
 application of, 301 
 casting process in, 301 
 deep saddle, 309 
 
 bases for, casting of, 309 
 investing of, 311 
 ring, casting of, 310 
 soldering to cap, 311 
 
 to saddle, 311 
 uniting of, 310 
 waxing of, to cap, 310 
 to saddle, 310 
 carving sides for plates, 311 
 cementing crowns in place, 
 
 313 
 finishing of, 313 
 grinding of, 309 
 impressions for, 312 
 models for, 312 
 wall to hold crown in place, 
 
 309 
 waxing sides for plates, 311 
 depth of bite for, 301 
 enlarging pulp canals for, 59, 61 
 investing of, 196 
 limitations of, 301 
 
 Porcelain crowns, root facing for, 113 
 selection of, 214 
 shade variation and blending of, 
 
 214 
 shapes of, 215 
 soldering of, 196 
 tjrpes of, 215 
 
 with cast base, casting process in, 
 200 
 for removable bridges, 301. 
 with soldered base in fixed bridges, 
 
 221 
 with wax base, casting process in, 
 201 
 faced crowns, 187 
 
 as abutments for extension 
 
 saddle bridges, 314 
 backing of, 192 
 finishing of, 195 
 single, investment for, 194 
 soldering of, 192, 194 
 waxing-up of, 192 
 spatula for, 194 
 Portable dark-room box for developing 
 
 radiograph film, 413 
 Post-puller, 345 
 
 Potassium in enlarging of pulp canals, 
 48 
 in treatment of putrescent pulp 
 canals, 23 
 Powdered sUex, properties of, 389 
 Prinz, Dr. Herman, method of divital- 
 
 izing pulp, 36 
 Prosthesis, 157 
 
 Prosthetic castings, gold for, 374 
 Prosthodontia and orthodontia, rela- 
 tion of, 151 
 Pulp canals of anterior teeth, 52 
 cleansing of, 54 
 instruments for, 54 
 Donaldson's, 54 
 sterilization of, 55 
 methods of, 55 
 superheated steam in, 56 
 constricted, 50 
 
 for all porcelain crowns, 61 
 for Downey crowns, 61 
 enlarging of, Gates-Glydden nerve 
 canal drills in, 58 
 instruments for, 58 
 Peeso's root reamer in, 59 
 for porcelain-faced crowns, 59 
 potassium in, 48 
 sodium in, 48 
 dioxide in, 48 
 filling of, 62 
 
 gutta-percha points in, 62 
 materials for, 62 
 location of, 46 
 of lower bicuspids, 52 
 
 molars, 49 
 opening of, instruments for, 47 
 
INDEX 
 
 453 
 
 Pulp canals, opening of, Kerr broaches 
 in, 47 
 putrescent, sterilizing of, 23 
 treatment of, 23 
 formalin in, 24 
 potassium in, 23 
 sodimn in, 23 
 dioxide in. 23 
 removal of pulp from, 54 
 sensitiveness after, 57 
 tenderness after, 57 
 tortuous, 50 
 of upper bicuspids, 51 
 
 molars, 47 
 with enlarged foramina, filling of, 
 
 63 
 work, x-rays in, 52 
 chamber, opening into, 46 
 exposure of, radiography and, 425 
 infection, treatment of, 24 
 Pulps, aching, treatment of, prepara- 
 tory^ to devitalizing, 41 
 ilevitalization of, 33 
 agents used in, 36 
 arsenic in, 38 
 
 danger of, 39 
 discoloring of teeth after, cause of, 
 34 
 prevention of, 34 
 Dr. Herman Prinz's method, 36 
 exceptions to, 33 
 heroic method of, 39 
 local anesthesia in, 44 
 novocaine in, 44 
 pressure anesthesia in, 41 
 sterilization of field of operation 
 
 in, 42 
 treatment i)reparatory to, 41 
 formative organs of, 33 
 inflamed, treatment of, preparatory 
 
 to devitaUzing, 41 
 vitality of, 33 
 Putrescent pulp canals, sterilizing of, 23 
 to treatment of, 23 
 formaUn in, 24 
 pfjtassium in, 23 
 sodium in, 23 
 dioxide in, 23 
 Pyorrhea alveolaris, radiography and, 
 436 
 relation of, to crown and bridge-work, 
 22 
 Pyorrheal conditions, relation of, to 
 crown and bridge-w(jrk, 23 
 
 Radiograph in crown and bridge-work, 
 
 408 
 abHcosH and, 428 
 anorrialif« in direction of roots 
 
 and, 434 
 
 Radiograph in crown and bridge-work, 
 anomalies in number of roots 
 and, 434 
 in shape of roots and, 434 
 dangers of, to operator, 423 
 
 to patient, 423 
 dental caries and, 425 
 for diagnosing field of operation, 
 
 409 
 foreign bodies and, 437 
 fractured roots and, 431 
 ill-fitting crown and bridges and, 
 
 438 
 impactions and, 426 
 imperfectly formed teeth and, 
 
 426 
 indications for use of, 424 
 measiu'ing roots and, 433 
 necrosis and, 426 
 outfit for, 410 
 
 position for making exposures of 
 
 cuspid and lateral, 415 
 
 of four upper anterior 
 
 teeth, 417 
 of impacted lower third 
 
 molars, 420 
 of lower anterior teeth, 
 
 418 
 of maxillary sinus, 421 
 of teeth posterior to lower 
 
 first bicuspid, 419 
 of upper right teeth, 416 
 proximity of roots to maxillary 
 
 sinus and, 434 
 pulp exposure and, 425 
 pyorrhea alveolaris and, 436 
 records of, interpretation of, 410 
 
 keeping of, 410 
 retained teeth and, 426 
 root absorption and, 424 
 
 fragments and, 435 
 root-canal fillings and, 426 
 technic of, 410 
 unerupted teeth and, 426 
 dental, literature on, 410 
 frosted white and ruby lamp, use of 
 
 in, 414 
 lead box for protecting unexposed 
 films. 412 
 glass diaphragm for use in, 411 
 portable dark-room box for develop- 
 ing films, 413 
 Refractory materials, 385 
 Itcmovable l)ridges, 206, 225. See 
 
 Bridges, removable. 
 Rei)airing crowns, 342. See Crowns, 
 
 repairing of. 
 Retained tc-eth, radiography and, 426 
 RetiJ.ining media, 336 
 
 cementing of fixed bridges, 337 
 
 of nimovable bridges, 339 
 gutta-pcsrclia, 341 
 
454 
 
 INDEX 
 
 Retaining media, oxyphosphate of zinc, 
 
 336 
 Rhodium alloys, gold and, 370 
 Richmond crowns, 187 
 backing of, 192 
 finishing of, 195 
 root facing for, 112 
 single, investment for, 194 
 soldermg of, 192, 194 
 waxing-up of, 192 
 spatula for, 194 
 Rigg's disease, bridge-work for, 351 
 split bar for special cases, 354 
 Stewart on, 351 
 
 tubes swung off side for abut- 
 ment crowns, 355 
 types of attachments, 352 
 variations of split pin and split 
 bar in, 351 
 Root absorption, radiography and, 424 
 amputation, 31 
 facers, Ottolengui's, 118 
 reamer, Peeso's 59 
 Roots, anomalies of, radiography and, 
 434 
 broken apart, treatment of, 71 
 below gum, fitting bands to, 145 
 
 models of, preparation of, 145 
 down, building up, with amalgam, 
 143 
 decayed below gum, fitting bands to, 
 145 
 models of, preparation of, 145 
 facing for Downey crowns, 113 
 for porcelain crowns, 113 
 in removable attachment for an- 
 terior teeth, 252 
 for Richmond crowns, 112 
 fractured, radiography and, 431 
 
 treatment of, 68 
 fragments of, radiography and, 435 
 lower anterior, trimming of, 107 
 
 instruments for, 107 
 measurement of, dentimeter for, 187 
 measuring of, radiography and, 433 
 perforated, treatment of, 66 
 proximity of, to maxillary sinus, 
 
 radiography and, 434 
 separated, treatment of, 71 
 upper anterior, trimming of, 102 
 instruments for, 102 
 
 Saddle bridges, abutments at both 
 ends, anterior, 334 
 deep, 309 
 
 bases for, casting of, 390 
 investing of, 311 
 ring, casting of, 310 
 soldering to cap, 311 
 to saddle, 311 
 
 Saddle bridges, deep bases for, uniting 
 of, 310 
 waxing of, to cap, 310 
 to saddle, 310 
 carving sides for plates, 311 
 cementing crowns in place, 313 
 finishing of, 313 
 grinding of, 309 
 impressions for, 312 
 models for, 312 
 
 wall to hold crown in place, 309 
 waxing sides for plates, 311 
 extension, 314 
 
 abutments necessary for, 314 
 porcelain-faced crowns, 314 
 
 top crowns, 314 
 telescope crowns, 314 
 adjustment of saddle to abut- 
 ments, 318 
 to ridge, 314, 317 
 buccal plates, carving for, 325 
 clamping to saddle, 328 
 impressions for, 326 
 investing of, 329 
 models for, 326 
 soldering of, 329 
 waxing for, 328 
 contraction of gold in soldering 
 and restoring of proper align- 
 ment, 321 
 cusps of, 324, 325 
 facings for, backing of, 324 
 beveling of, 324 
 grinding of, 323 
 selection of, 323 
 with gold occlusal surfaces, 
 use of, 323 
 finishing of, 333 
 fusible metal counterdies and 
 
 dies for, 327 
 grinding of, 333 
 impression for, 315 
 investing of, 320 
 
 for final soldering, 330 
 lingual plates, carving for, 325 
 impressions for, 326 
 models for, 325 
 soldering of, 331 
 
 bridge and, 329 
 waxing for, 325 
 model for, 315 
 polishing of, 334 
 reinforcing of, 316 
 soldering to abutment cap, 320 
 of body to bridge, 330 
 cleansing after, 332 
 drying after, 332 
 trimming and waxing to abut- 
 ment caps, 320 
 vulcanite attachments for, 322 
 Saddles, construction of, new series of 
 alloys and, 407 
 
INDEX 
 
 455 
 
 Saddles in porcelain crowns for anterior 
 
 teeth, 302 
 Scalers, enamel, 103 
 Shears, curved, 168 
 straight, 168 
 
 use of, in festooning band, 167 
 Shell crowns, repairing of, 342-344 
 Silex, powdered, properties of, 389 
 Silver, alloj's of, melting points of, 362 
 Sodium dioxide in enlarging of pulp 
 canals, 48 
 in treatment of putrescent pulp 
 canals, 23 
 in enlarging of pulp canals, 48 
 in treatment of putrescent pulp 
 canals, 23 
 Soldered joint bands, 164 
 Soldering, autogenous, 159 
 
 of buccal plates on extension saddle 
 
 bridges, 329 
 in cap" in split pins used on teeth of 
 
 divergent angles, 299 
 of combination crown in tube, 244 
 of cusps of telescope crowns, 239 
 of Downej^ crowns, 196 
 of extension saddle bridges, 330 
 fluxes for, 400 
 
 formula for, 401, 404 
 of inlay abutments for anterior teeth 
 
 with bridge, 267 
 of interchangeable facings, 219 
 investment compounds for, 385 
 
 formula for, 391 
 of lingual plates on extension saddle 
 
 l)ridges, 331 
 of porcelain crowns, 190 
 of split pins, 287 
 
 to cap, 249 
 of tubes, 281 
 
 used on teeth of divergent angles, 
 299 
 sweating process, 159 
 advantages of, 159 
 Solders, gold, 381 
 
 alloys for, 382 
 Spatula for mixing oxy phosphate of 
 zinc, 33li 
 for waxing porcelain-faced crowns, 
 194 
 Richmond crowns, 194 
 Split pins, 284 
 alloy for, 284 
 burnishing of, 290 
 clasp wire, 285 
 
 rniarging necks for, 247 I 
 
 filing of, 287 j 
 
 file and pin vise in, use oi, 288 
 (j])(:u at end, 291 
 fitting of, into tubes, 217 
 forging h.alves in «)ntact, 287 
 half-roiirid wire, 284 
 haiiiniering halvr;H in contact, 287 
 
 Split pins, iridio-platinum wire, 284 
 long, closed at end, 291 
 making of, technic of, 286 
 platinize! gold, 285 
 removable attachment for anterior 
 
 teeth, investing of, 255 
 smoothing of, 290 
 soldering of, 287 
 
 to cap, 249 
 solid pin sawn through, weakness 
 
 of, 384 
 use of, reversal of usual type, 297 
 on teeth of divergent angles, 298 
 bands in, fitting of, 298 
 fitting in cap, 299 
 impressions in, 298 
 making outer half cap, 299 
 models for, 298 
 roots in, preparation of, 298 
 soldering in cap, 299 
 Weinstein's devices for, 292 
 Sterilizing putrescent pulp canals, 23 
 Stewart, Howard J., on bridge-work 
 
 for Rigg's disease conditions, 351 
 Stretching pliers, 160 
 Stumps, protection of, from encroach- 
 ment of gums, 126 
 Sulphuric acid, aromatic, in treatment 
 
 of dento-alveolar abscess, 27 
 Supporting abutments, 272 
 Swaging device for cusp matrices, 182 
 
 for flattening floors, 188 
 Sweating of bands, 163 
 Syringe, cement, 340 
 
 Teeth, anterior. See also Anterior 
 Teeth, 
 banded crowns for, 187 
 jacket crowns for, 197 
 broken-down, impressions of, taking 
 of, 144 
 models of, preparation of, 144 
 decayed, crowns for, making of, 105 
 impression of, 148 
 models of, 149 
 preparation of, 147 
 discoloration of, after devitalization 
 of pulp, cause of, 34 
 ))rcvention of, 34 
 elongation of, from lack of occlusion, 
 
 213 
 impacted, radiography and, 426 
 imperfectly formed, radiography and, 
 
 426 
 irregularities of, slight, 152-1,53 
 
 troaimoiit of, 1.56-158 
 lingually inclined, impressions of, in 
 
 .sections, 131 
 loose, relation of, to crown and 
 bridge-work, 22 
 
456 
 
 INDEX 
 
 Teeth, lower anterior, impressions of, in 
 sections, 130 
 of lower jaw, relative strength of, 72 
 necrosis of, radiography of, 426 
 retained, radiography of, 426 
 as supports for bridge-work, relative 
 
 strength of, 72 
 trimming of, for bands, 82 
 
 for caps, 82 
 typical shapes of, 78 
 unerupted, radiography of, 426 
 of upper jaw, relative strength of, 72 
 Telescope crowns, 227 
 
 as abutments for extension saddle 
 
 bridges, 314 
 alloys for, 227 
 
 Weinstein's, 228, note. 
 construction of, new series of 
 
 alloys and, 406 
 contour of, casting of, 240 
 cusps of, casting of, 240 
 preparation of, 238 
 selecting of, 238 
 soldering of, 239 
 durabihty of, 228 
 inner cap of, cutting bands for, 229 
 fitting bands to stump, 229 
 measurement of, 229 
 polishing of, 231 
 reinforcing of, 231 
 sweating floor to, 230 
 outer cap of, burnishing of, 235 
 contour of, 231 
 finisliing of, 240 
 fitting over inner, 234 
 making of, 233 
 measurement of, 233 
 occlusal end of, 235 
 removal of, from inner, 235 
 sweating floor to, 236 
 trimming of, 236 
 technic of, 228 
 trimming tooth for, 228 
 with tube and split pins, 241 
 Tin, fitting to backing in repairing 
 broken facings, 347 
 foil, use of, in porcelain crowns for 
 anterior teeth, 305 
 Tubes, alloys for, 276 
 
 contraction of, on soldering, 247 
 
 drawn, 276 
 
 drilled, 276 
 
 entrance of, countersinking of, 247 
 
 filing of, 283 
 
 fitting of, in combination crowns, 243 
 
 split pins into, 247 
 in inlay abutments for molars, 269 
 iridio-platinum, 276 
 making of, hammer-headed hand- 
 vise in, 278 
 by mandrel process, 276 
 
 Tubes, making of, technic of, 280 
 plate for, 278 
 in removable attachment for anterior 
 
 teeth, enlarging entrance to, 254 
 rounding end of, 283 
 sizes of, 284 
 soldering of, 281 
 
 of combination crown in, 244 
 of floor of, 283 
 trimming of, 283 
 
 use of, reversal of usual type, 297 
 on teeth of divergent angles, 298 
 adjusting of, 299 
 bands in, fitting of, 298 
 impressions in, 298 
 models for, 298 
 roots in, preparation of, 298 
 soldering of, 299 
 
 Unerupted teeth, radiography and, 
 
 426 
 Upper anterior roots, trimming of, 102 
 bicuspids, cusps of, 172 
 
 pulp canals of, 51 
 
 trimming of, 101 
 jaw, teeth of, relative strength of, 72 
 molars, first, cusps of, 169 
 
 pulp canals of, 47 
 
 second, cusps of, 169 
 
 third, cusps of, 170 
 
 trimming of, 97 
 right teeth, radiography of, position 
 
 for, 416 
 
 W 
 
 Wax, tough adhesive, use of, in impres- 
 sions, 127 
 Weinstein's alloy for telescope crowns, 
 228, note. 
 artificial stone, 120 
 
 impressions with, filling of, 121 
 preparation of, 121 
 separation of, 122 ' 
 
 device for making split pins, 292 
 drawing wire, 293 
 finishing, 295 
 pohshing, 295 
 swaging, 295 . 
 paralleling device for abutments, 
 208 
 Window crowns, 197 
 
 X 
 
 X-rays in crown and bridge-work, 408 
 
 Zinc, oxyphosphate of, 336 
 
E^te 
 
RK666 P^4 
 
 Peeso 
 
 Jrown and bridge work 
 
 MAY 31 1943 A '^ .V<_^iA.c^