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 A 
 
 New Classification of Human 
 
 Tooth Forms With Special 
 
 Reference to a New System of 
 
 Artificial Teeth 
 
 J. Leon Williams, D.D.S., L.D.S. 
 
 Published by 
 The DENTISTS' SUPPLY CO. 
 
 220 WEST 42d ST., NEW YORK 
 
 Reprinted from Dental Digest 
 

Digitized by the Internet Arciiive 
 
 in 2010 witii funding from 
 
 Open Knowledge Commons 
 
 http://www.archive.org/details/newclassificatioOOwill 
 
A NEW CLASSIFICATIO:^^ OF HUMAN" TOOTH FOKMS; 
 
 WITH SPECIAL REFEKENCE TO A NEW 
 
 SYSTEM OF ARTIFICIAL TEETH. 
 
 By J. Leoi^ Williams, D.D.S., L.D.S. 
 
 "It is only what happens that matters." 
 
 Three years ago I presented before this Society the outline of a 
 scheme for a system of artificial teeth, and a plea for a new order of 
 things in dental prosthesis. I had but little material evidence to lay 
 before yon in support of the contentions advanced, for that was impos- 
 sible. But I had something in the nature of a vision, in which I 
 saw an important branch of our professional service redeemed from the 
 low and almost contemptible position it has long remained in. Some- 
 thing of that vision I must have been able to get before you, for the 
 substance of it met with your unqualified approval and you passed a 
 strongly worded resolution giving official expression to that approval 
 and asking the manufacturers to take up the work I had outlined and 
 proceed with it along the lines I had formulated. 
 
 Such an undertaking, at that time, must have seemed hazardous 
 to the manufacturer. It called for a very heavy initial outlay. There 
 was nothing in the work that could be patented and no way in which 
 the pioneer in the new field could be protected from the unfair competi- 
 tion which imitation, without initial outlay, would make possible. 
 
 But in spite of these unfavorable conditions we were fortunate 
 enough to find a manufacturing company with sufficient faith, cour- 
 age and enterprise to take up and carry out the work in a liberal 
 spirit; and to-day I come before you again to announce the early 
 completion of our long labors. 
 
 The whole scheme which I laid before you is not completed 
 in its entirety, but there is, we believe, quite sufficient evidence to 
 offer of so great an advance in this field as to make the old order 
 forever intolerable, and thus to place upon you the obligation to so 
 encourage the manufacturer that he will carry all phases of the work 
 through to its final consummation. 
 
J. Leon Williams, D.D.S. 
 
 And now, at the very outset of my lecture, I should like to make 
 it perfectly clear that this system of standardizing tooth forms is 
 not offered to the dental profession as a mere improvement on what 
 has preceded it. It is not an old building with a redecorated interior 
 and a new facade. It is a new structure throughout. Its foundations, 
 I believe, are well and truly laid on a solid basis of scientific fact, 
 with a superstructure designed in accordance with a principle of 
 unity, without which good art is impossible. And when our work has 
 been carefully examined, when its full scope and the measure of its 
 achievement shall have been clearly seen and understood, I think 
 the universal query will be the one often propounded on the comple- 
 tion of some important undertaking having for its main object a 
 practical benefit to humanity, "Why was this not done before?" The 
 logic and reason of a completed work is so frequently self-evident that 
 we cannot avoid asking that question. But in doing so we overlook 
 the tremendous power of the psychology of habit, the great difficulty 
 in getting outside ourselves for a point of view, and the comforting 
 feeling of ease in following lines of least resistance. It brings no 
 sense of effort or fatigue to take a thing for granted. It is in the 
 overcoming of these psychical conditions that the would-be reformer 
 often finds his greatest task. And that is saying more than a little in 
 this instance, for the material conditions have sometimes presented a 
 formidable front. But the knowledge that every difficulty removed 
 and every obstacle surmounted has contributed something toward 
 placing the finished work on a higher level than it would otherwise 
 have reached is a very gratifying reflection. 
 
 -^ «<fe ««fe 
 
 In an ancient book in which there are many wise sayings it is 
 
 written: "To everything there is a season, and a time to every pur- 
 pose under the heavens; — a time to kill and a time to heal; a time 
 to break down and a time to build up." To-night I shall address 
 myself solely to the former of those two functions. I have to under- 
 take, in the short space of an hour or so, to break down the old sys- 
 tem of prosthetic dentistry.^ 
 
 From the standpoint of the reasonableness and force of the proofs 
 at hand, the task seems to me not a difficult one, but I should be a 
 very poor student of human nature if I had not discovered that it 
 is far easier to convince a man's reason than it is to break up the 
 established routine of his bad habits in craftsmanship as in many other 
 things. 
 
 ^Only the first half of this paper, the part devoted to destructive criticism, was read on 
 the date above mentioned. The latter part of the article was read on March 10. 
 
"A I^Tew Classification of Tooth Foems" 
 
 However, I am greatly encouraged in my belief that the bad 
 old customs of practice in dental prosthesis are about to receive a 
 rude shock by my knowledge of the fact that in no coimtry in the 
 world are inferior methods, systems and machines so quickly dis- 
 carded or "scrapped" the moment their inferiority to something new 
 is demonstrated and established, as here in America. American busi- 
 ness men found out long ago that it is the truest economy and the 
 surest way to success to throw away an inferior method of produc- 
 tion, or a method which produces an inferior article, the instant better 
 methods are discovered. That policy has made Americans the great- 
 est leaders in the business world. It has sent all the nations of the 
 earth here to learn and copy American methods, and to-day you may 
 find those methods being put into effect in the remotest corners of 
 the world. So strong and vital is this influence of American progress 
 that Gugiielmo Ferrero, the distinguished Italian historian, says "it 
 is the one idea that has taken deep hold of the European masses 
 during the last fifty years." It has certainly created a new outlook 
 and a new spirit in the world. It has made men more self-reliant 
 and given them a greater confidence in their own inherent capacity 
 to subdue the stubborn and apparently antagonistic forces of ISTature 
 to human will. It is in that American spirit which says, in the 
 language of the people, "The best we can have is none too good," that 
 I have come here to-day to ask you to discard, to throw away, to utter- 
 ly destroy and obliterate a system of prosthetic dentistry that has ex- 
 isted far too long, and to establish in its place something more in 
 keeping with the reputation for progress and scientific achievement 
 and character that our country enjoys in other fields throughout the 
 world. 
 
 •^ *% '^ 
 
 Dr. Ebersole, in a stirring and eloquent call, published in the 
 Dental Summary last January, warned you that dentistry was not 
 keeping in the van of American progress. If that is true in any 
 degree of dental practice as a whole, then it is most emphatically true 
 of dental prosthesis. And on that point I believe there are no two 
 opinions. 
 
 To remedy the present deplorable condition of things in this 
 field the first important step is to find out the cause or causes of this 
 condition. In my judgment, the chief cause is to be found in the 
 false basis of the present methods and theories for the selection of 
 porcelain teeth and it is, as I have indicated, principally with this 
 theme that I shall deal this evening. 
 
J. Leon Williams, D.D.S. 
 
 I believe that the chief reason why prosthetic dentistry has fallen 
 so low in the estimation of the profession is that most dentists have 
 an instinctive feeling that with such teeth as have heretofore been 
 supplied, no amount of effort on their part would produce satisfactory 
 scientific and artistic results. I wish, therefore, to try and make it 
 clear why the present system is weak and poor. I want to point 
 out its imperfections and fallacies, its dogmatic assumptions that 
 have no foundations, its ignorance of scientific facts and artistic prin- 
 ciples, so that there may be no qualms of conscience, no shadow of 
 regret in saying good-bye to it. This will take a little more of your 
 time than you are accustomed to give to listening to a paper or lecture. 
 But I ask you to remember that the occasion is a little unusual. 
 You are not often asked to listen to reasons why you should make a 
 complete and radical change in an important branch of practice. 
 
 Two great defects have characterized the manufacture of arti- 
 ficial teeth from the date of their invention do\vn to the present time, 
 a conventionalized or generalized tooth form, devoid of definite char- 
 acter, and the absence of any system of classification, or any funda- 
 mental principle or central idea on which the work is based. This 
 statement applies with equal force to the shapes of the incisors and 
 the masticating surfaces of the bicuspids and molars. 
 
 '^ '^ '^ 
 
 There are very definite reasons why artificial teeth should have 
 continued to remain, for such a long period in the history of dentistry, 
 of a defective and unnatiural character and without systematic ar- 
 rangement. It was hardly possible to have any satisfactory classifica- 
 tion of natural teeth, neither was it possible to have fine, natural, 
 artistic forms of artificial teeth without a knowledge of the primary 
 forms of natural teeth. That statement may sound somewhat curi- 
 ous to you, but I hope to make it quite clear, presently, that the pri- 
 mary forms of human teeth have, hitherto, not been known. Like 
 old friends, whom we sometimes meet and pass on the streets when 
 our minds are preoccupied, they have been seen and not recognized.^ 
 
 But to produce a perfect system of artificial teeth there is re- 
 quired not only an intimate knowledge of all the facts of ISTature, but 
 also familiarity with the principles of design through which a har- 
 mony of related parts, that is often absent in ISTature, may be secured. 
 
 SMany examples could be adduced to show that long observation does not always result 
 in accurate perception. Herbert Spencer, at different periods in his life, held three distinct 
 opinions about the color of shadows, each one, as he says, "based on years of observation. 
 And his final recognition of what he regarded as the exact truth was due to a suggestion he 
 got while reading a popular work on optics. 
 
"A !N'ew Classificatioit of Tooth Fokms" 
 
 This very essential qualification for tlie production of artificial teeth 
 seems to have been entirely overlooked. 
 
 As a matter of fact, no serious attempt has ever before been 
 made to investigate any portion of this field with scientific thorough- 
 ness and accuracy. All the honors in dentistry have been reserved 
 for other departments, with the result that many men who have na- 
 tional reputations in what is called operative dentistry, make a mighty 
 poor showing when they turn their hands to dental prosthesis. 
 
 Whether or not the reason for this is the one I have suggested, it 
 is, nevertheless, certain that this branch of practice presents a far 
 finer opportunity for the exercise of artistic skill, scientific knowledge 
 and sound judgment than is to be found in any other phase of den- 
 tistry. If any one has any doubts on that point I hope he will reserve 
 his final opinion until he has heard the full "argument for the plain- 
 tiff." 
 
 <^ «^ -^ 
 
 You will, I think, be able to see more clearly the relation and 
 significance of the facts presented if I state specifically the main 
 objects I have in view in this paper. I shall attempt to destroy all 
 belief in temperamental forms of teeth, for I regard this as one of 
 the most fundamental errors in the present system. I shall try to 
 show that while there are slight variations in the teeth of different 
 peoples, there is no such thing as racial types of teeth. I hope to 
 convince you that the oft repeated statement that Nature always pro- 
 duces teeth in harmony with face and feature is a mistake due to 
 lack of careful observation. And I expect to prove that it is impos- 
 sible to produce a scientific and satisfactory system of artificial teeth 
 by simply copying sets of natural teeth. 
 
 Let us begin then, with the subject of temperamental classifica- 
 tion of teeth. And let me note at the outset that some of our best 
 writers on dental prosthesis say quite frankly that they make use of 
 this theory for lack of a better. 
 
 In his excellent book, recently published, my good friend. Dr. 
 Wilson, of Cleveland, has introduced a brief resume of the theory, 
 but I think I discover evidences that he is not altogether satisfied with 
 it. Other writers, after admitting that there are great variations 
 within the limits of the normal, afterwards say that with few excep- 
 tions the forms and contours of the teeth are harmonious with those 
 of the body, but they give us neither principles nor facts on which 
 such a statement is founded. 
 
J. Leon Williams, D.D.S. 
 
 One author savs further that "it is difficult, in some cases, to de- 
 cide positively to which variety (of temperament) a special case be- 
 longs . . . K^ot infrequently the indications are even contradic- 
 tory . . . and no rule can he given that will not fail in numerous 
 instances." I submit that a theory of this character is much more 
 likely to mislead than guide the student and beginner, and that it 
 would have been better to drop it altogether in dentistry, as was done 
 in other branches of science long ago. But this course has not been 
 taken, and the theory still has some ardent and dogmatic advocates. 
 I am sure you will agree, therefore, that it is better to subject the 
 claims of this teaching to a thorough critical examination before put- 
 ting forward the new classification. 
 
 'fe -^ «^ 
 
 Let us first glance at the great, authoritative modern works of 
 reference, to see what they have to say on the subject of temperament. 
 
 Our first effort is a little disappointing. 
 
 We open the Encyclopaedia Britannica at the place where the 
 word should be, but we do not find it. It is completely ignored. We 
 consult the Xew American Encyclopaedia of Science and do not fare 
 much better. The word is there, it is true, but used in a sense that 
 connotes nothing of the physical or mental characteristics of human 
 beings. It simply has reference to certain technical matters about 
 musical instruments. Gould's Dictionary of Medicine says that the 
 word is spoken of as a vague term or a term vaguely applied. This 
 authority further says that although the original doctrine has long 
 since lost its sigTiificance, it is permissible to use it in describing pre- 
 disposition to types of mental action : and that is the manner in which 
 it is sometimes used by good modern writers.* Jonathan Hutchinson, 
 F.R.S., with whose work on the teeth you are all familiar, made a 
 careful examination of the claims of the temperamentalists and here 
 is his verdict: "As yet I fear we must say that the labors of the 
 physiognomist and those of the students of temperament have been 
 alike disappointing. Whoever will set himself the task of attempt- 
 ing to classify a given number of individuals according to their tem- 
 peraments will, I think, soon find himself baffied." 
 
 The simple truth of the matter is that this whole theory of tem- 
 perament has been completely discredited and entirely abandoned by 
 
 *Dr. E. B. Taylor, F.R.S., author of an important work on Anthropology, says: "Anthro- 
 pology finds race-dififerences most clearly in stature and proportions of limbs, conformation of 
 the skull and the brain within, characteristics of features, skin, eyes and hair, peculiarities of 
 constitution, and mental and moral temperament." The italics are mine. Dr. Keane, one of 
 the very greatest authorities in Anthropology, applies the word "temperament" solely to psy- 
 chical qualities. 
 
 6 
 
'"A 'Nnw CiiAssiFiCATioisr or Tooth Foems" 
 
 all scientific men of standing — except a few of those who rule over 
 the destinies of dentistry. And for them I fear that a mere reference 
 to authorities, however eminent, will hardly be sufficient. We shall 
 have to go a little deeper into the matter, to completely satisfy them. 
 But before getting down to the real work of proof, let us have a side- 
 long glance at those pretentious tables of temperamental classifications 
 with their air of exhaustive research and minute discrimination, which 
 figure so prominently in our textbooks on prosthetic dentistry. 
 
 You are all familiar with the results of the researches of Dr. 
 Black and Mr. Charles Tomes into the question of comparative hard- 
 ness or softness of teeth. You know that working quite independ- 
 ently they both reached the conclusion that the variation in the hardness 
 and softness of teeth was a negligible quantity. The differences are 
 so small as to be a matter of no importance. But if we turn to those 
 tables in our textbooks on prosthetic dentistry which profess to give the 
 temperamental characteristics of teeth, we find the so-called lymphatic 
 teeth, and combinations of the lymphatic, bilious and nervous teeth, 
 described as "soft and brittle" ; ''soft and frail" ; "soft and weak" ; 
 "soft and sensitive" ; "mixture of flinty and chalky" ; "soft, weak and 
 chalky," etc., etc. 
 
 '^ '^ '^ 
 
 I shall show you presently that all so-called temperamental char- 
 acteristics must have arisen in racial characteristics. With that fact 
 in view, the question, "Do those races from which the so-called lym- 
 phatic, bilious and nervous temperaments have arisen have teeth that 
 are markedly more soft and frail than the sanguine races ?" need only 
 be asked to see the utter absurdity of the whole business stand revealed, 
 even without the classical work of Black and Tomes to prove it. 
 
 Then take the indications as to shape and size. We are told that 
 the teeth of a bilo-nervous person are "medium large" and "long and 
 often narrow" in shape, while the nervo-bilious teeth may be "large 
 or small" and "broad or long." Is that the sort of instruction a dental 
 student requires to enable him to produce harmonious relations be- 
 tween tooth form and facial contour ? If you were given a blank form 
 of face of a definite size and of the oval type, let us say, and required 
 to describe the character of the features necessary to produce an har- 
 monious whole, would you say that the mouth might be short or long, 
 the nose large or small, the eyes near or widely separated ? In all the 
 wearisome contradictory and irrelevant details of these tables there is 
 never a hint of fundamental principle on v/hich a student could take 
 his stand for the exercise of his taste and judgment, 
 
 7 
 
J. Leox Williams, D.D.S. 
 
 Many of vou will remember that in the paper which I read here 
 three years ago I pointed out that there was really no foundation for 
 the theory of tempersimental forms of teeth. I exliibited photographs 
 of individuals of precisely the same temperaments, according to the 
 rules of the theory, but showing teeth widely different in shape. Since 
 then text books on prosthetic dentistry have appeared in which this 
 theory is given a prominent place. But even more significant, per- 
 haps, is the prominence given to this theory in the recently issued 
 catalogues of two of the oldest and most prominent manufacturers of 
 artificial teeth. I say ''more significant" because the prominent manu- 
 facturers have the best of reasons for making it their business to know 
 the general trend of belief and opinion in the profession. 
 
 In the latest catalogue of one of the largest and oldest firms in 
 England we find illustrations of the three sets of teeth in the lower 
 row of Illustration Xo. 1, and at the bottom of the pages on which 
 they are sho^vn we read — "The dentures illustrated above are distinct- 
 ly typical of the temperaments described by Spurzheim," and then, 
 as though to specially emphasize the statement that these particular 
 teeth are '^'^ distinctly typical/' they add that ''it must be remembered 
 that a pure type is seldom met with, the majority of the cases being 
 combinations of the features of more than one temperament." The 
 temperaments represented in the three dentures I have selected are 
 supposed to be the "sanguine," the "bilious" and the "nervous." I 
 will ask you to look very closely at the central incisors, always the 
 most characteristic teeth in any given set. and see if you can detect 
 the very least typical difference. The teeth are not only of one type, 
 but they are very nearly indistinguishable as to form and size. Except 
 as to color, there is not a ghost of a reason why these sets should not 
 all change places. 
 
 '^ '^ '^ 
 
 A representative American firm has also published illustrations 
 of teeth designed for the pure temperaments, as shown in the upper 
 row of illustration ^o. 1. 
 
 Please compare the corresponding t%^es of the two manufactur- 
 ers. Xo comment from me is necessary, and I will make none, except 
 to say that these teeth are not made by firms whose reputation is ever 
 called in question. They are firms which are rightly and justly jeal- 
 ous of the high reputation they have honorably earned. But can you 
 look at the specimens of these two companies, each claiming its own 
 work as typical, and each so widely dift'erent from the other as to 
 make comparison positively grotesque, without thinlving that it is about 
 time we heard the last of temperamental classification of teeth; that 
 
 8 
 
SANOUISI-IOUS 
 
 CM? fBSflP f!RW 
 
 Illustration No. 1 
 
 Lower row, three sets of teeth from a well-known English manufacturer supposed to be 
 typical of the temperaments described by Spinzheim. All three sets are of one type, but very 
 nearly of one form of that type. 
 
 The upper row shows three sets made for these same temperaments by a long-established 
 American manufacturer. Each form is so different from the form of the English manufacturer 
 for the same temperament as to make comparison diificult. 
 
 Illustration No. 2 
 
 Two skulls of unlike form with teeth identical in type and size. No relation between form 
 or size of skull and the form or size of teeth. 
 
"A IsTew Classification of Tooth Eoems" 
 
 it is about time we began looking for something a little more scientific 
 as a basis for tooth form, and also, if I may say so, about time that 
 some one designated and officially indorsed by the profession, to ex- 
 press their views and wishes, took a hand in the designing of artificial 
 teeth? 
 
 There are several phases of this theory of temperament, but they 
 all overlap more or less. This may sometimes cause an unavoidable 
 appearance of redundance in the proofs brought against these different 
 phases. And I fear that this fault of redundance, or perhaps it might 
 more correctly be called repetition, will appear more or less through- 
 out the paper. There is so much that is entirely new and foreign to 
 all former teaching in my paper, that it has seemed to me often neces- 
 sary to present the same facts from more than one point of view. 
 
 One writer on the subject of temperament says: "In these tem- 
 peramental differences, no single sig-n is more sig-nificant than is to 
 be found in the physical characteristics of the teeth — their size, shape, 
 color, density and alignment being as much an index as is the distinc- 
 tive complexion, the color of the eyes, hair, etc." A little farther 
 down the page it is said: "The law of harmony thus found in ISTature 
 between the teeth and other physical characteristics requires — " etc., 
 etc. And once more: "The careful observation and recording of these 
 co-relations would go far toward making prosthetic dentistry an exact 
 science." Here we have three variations of an assumption that iSTature 
 always produces teeth that in form and size are in perfect harmony 
 with the face and the individual features of the face. We often meet 
 this assumption in our text books and in magazine articles. On what 
 is it founded ? 
 
 •^ '^ '% 
 
 I have never heard anyone assert that all the other features of 
 every human face were in perfect harmony. The most of us have 
 seen many faces on which we would pass the observation of old Omar 
 Khayyam — if the "sorry scheme of things" were entrusted to us "would 
 we not shatter it to bits and then remould it nearer to our heart's 
 desire ?" The great teacher of science, Haeckel, is almost brutal in 
 his remarks on this point. He says in his "Evolution of Man" : "If 
 we compare the face of the long-nosed ape with that of abnormally ape- 
 like human beings, the former will be admitted to represent a higher 
 stage of development. There are still people among us who look especially 
 to the face for the 'image of God in man.' The long-nosed ape would 
 have more claim to this than some human individuals one meets." Is 
 there anything more evident to us as we walk up and down the streets 
 or stand in any place where our fellow mortals congregate, than the 
 
 9 
 
J. Leon Williams, D.D.S. 
 
 incongruities of Nature? Even the most fortunate would probably 
 not be willing to give an absolutely unqualified receipt in full to Na- 
 ture on taking a critical survey of himself in his mirror. Why, then, 
 should we assume that Nature always produces teeth in perfect har- 
 mony with face and features? Why should they be an exception to 
 the almost universal rule to the contrary in other particulars 'i The only 
 explanation I can suggest for this strange inconsistency is that an accept- 
 ance of the temperamental theory made it necessary. It is, in fact, a 
 phase of that theory. And when we have once given our unreserved 
 consent to a theory it is astounding how completely oblivious we 
 become to the most obvious facts. Let me put a few of the facts bear- 
 ing on this question before you. Here is a photograph of two skulls 
 (Illustration No. 2). You will observe that the difference in general 
 contour is very marked. But the teeth, you see, are identical in size and 
 type. If either set is in perfect harmony with size and contour of face, 
 the other set cannot possibly be so. 
 
 Here are two more (Illustration No. 3), a very wide and a very 
 narrow skull. Think what a striking difference there must have been 
 in the facial contour of the two individuals those skulls represent. But 
 you see the widest and shortest teeth are in the long, narrow skull. And 
 here (Illustration No. 4) are two more from the Andaman Islands — 
 both skulls from the same race. Here again the smaller skull has the 
 larger teeth. Note also that they are not of a different type. 
 
 '^ '^ '^ 
 
 Here we have four skulls (Illustration No. 5) so nearly alike in 
 size and contour that a single set of teeth would be just as suitable for 
 one as another of them, but look at the difference in the natural teeth. 
 At least three of those must be examples of disharmony. A glance at 
 the teeth is sufficient to demonstrate the mistakes of Nature. I could 
 take up the whole evening in showing you examples of this sort, 
 but as further proof on this point will appear incidentally when I 
 am considering other phases of my subject, I will not dwell longer 
 on it now. Unless someone can advance good and satisfactory reasons 
 for believing that Nature is more solicitous about the harmonious 
 relations of our dental organs with other features than she is about 
 those of our eyes, ears or noses, we will conclude that the subject is al- 
 ways open to the intelligent criticism of an artist in teeth. 
 
 The advocates of the temperamental theory always assume that 
 when a man and a woman of opposite temperaments mate, the off- 
 spring will be a blend of the two temperaments. To a certain limited 
 extent this may sometimes be the case, but more frequently we see a 
 juxtaposition, so to say, of the salient features of both parents. This 
 
 10 
 
Illustration No. 3. The widest and shortest teeth are in the narrow skull 
 
 Illustration No. 4. Two skulls from the Andaman Islands. The smaller skull has the larger teeth 
 and of different type, than the other 
 
"A N^EW CLASSIFICATIOISr OF ToOTH FoKMs" 
 
 might ]iave been known either from observation or from a knowledge 
 of the more recent researches in heredity. 
 
 The works of Mendel, Weissman, Galton, Thomson, Bateson and 
 others have made it clear that certain characters are dominant in one 
 parent and other characters in the other. One child may inherit the 
 general facial peculiarities of the father, and the complexion, color 
 of eyes and hair, and the teeth of the mother. In another child these 
 conditions may be reversed. In Sicily, that old battle ground of the 
 races, where the blood of the blue-eyed, fair-haired followers of JSTor- 
 man Roger has mingled with that of the Arabs, I ha,ve often seen just 
 such effects of this crossing of types as I have mentioned, and one may 
 see in Ireland people with black hair, dark skin and blue eyes.^ 
 
 What is the value of the temperamental theory of tooth form in 
 instances like these? 
 
 Wfe <<fe <^ 
 
 And now, consider for a moment the basis on which the whole 
 theory rests. It is founded on the idea of four groups or classes of 
 individuals called the pure temperamental types and known as the 
 sanguine, the nervous, the bilious and the lymphatic, in accordance 
 with the alleged dominance of the physiological functioning of the 
 blood, the nerves, the bile, or the lymph. What do the advocates of 
 this theory mean by the dominance of these systems ? Obviously but 
 one thing can be meant, and that is that the action of the heart or 
 the liver or the lymphatic system or the nervous system is stronger or 
 dominant in the individuals characterized by these terms. People of 
 the sanguine temperament should show a stronger action of the heart, 
 those of the bilious temperament greater activity of the liver and 
 people of the nervous temperament should be distinguished by greater 
 intellectual achievements and brain power generally. 
 
 Well, I have a large collection of photographs of some of the most 
 eminent persons of this country and Europe and I find that all forms 
 of faces and physical characteristics are included among the ablest 
 and most intellectual people of the world. 
 
 ^Broca and Thurnam, in the Memoirs of the Anthropological Society, describe a group of 
 sixteen ancient skulls, nearly all perfect, found in France at Nogent-les-Vierges. Three of 
 them are described as the dolichocephalic skulls of Aryan stock, eight as the brachycephalic 
 of Mongolian origin and five as a cross of the two. These latter had the high, narrow fore- 
 head of the long headed race, while the middle and occipital regions of the skulls had the 
 width and fulness of the round headed race. 
 
 Thomson, in his fine work, "Heredity," says: "A white man of considerable intellectual 
 ability marries a negro woman of great physical beauty and strength: the result may be — has 
 been a mulatto, who inherits some of his father's intellectual virtue and some of his mother's 
 physical strength." Again, "If a tall variety of (sweet) pea be crossed with a dwarf, all the 
 offspring are tall, and among their offspring in turn three-fourths are tall and one-fourth 
 dwarf, but none between the two." The italics are mine. 
 
 Thomson further says, when speaking of Mendel's law: "Experimental work has driven 
 home the conception of unit characters . . . that are inherited independently. 
 
 11 
 
J. Leon Williams, D.D.S. 
 
 But it may be pertinent to ask who lias ever made any experi- 
 ments of a severely scientific character to prove that the action of the 
 heart is stronger in so-called sanguine persons, or the liver more active 
 in bilious persons, or the brain larger in the alleged nervous tempera- 
 ment ? Who has ever conducted such experiments to prove anything 
 about temperament as indicative of physical characteristics ? 
 
 Who has ever determined the temperament of a negro or an Arab ? 
 Are the individuals of all races except Europeans, alike in their phys- 
 ical and psychical characters ? If not, what physical peculiarities in a 
 Chinaman, a native of iiustralia or a Hindoo correspond to those al- 
 leged to be indicative of the nervo-sanguine temperament in an Ameri- 
 can? 
 
 Who has ever got together, even a dozen people of one tempera- 
 ment, selecting them by their alleged physical temperamental peculiar- 
 ities witliout looking at their teeth, and then examined the teeth to 
 see if they were all alike or of one type ? 
 
 If that simple experiment had ever been made it would have 
 been seen that this pretentious structure (the temperamental theory) 
 is as frail as a house of cards and as empty as a soap bubble. A recent 
 writer in the Edinburgh Review says: ''The greatest discovery ever 
 made in philosophy was that the way to discover whether a thing is 
 present is to look and see. It was proclaimed by Aristotle in the an- 
 cient world and by Francis Bacon in the modern world." The extent 
 to which that simple rule is neglected is one of the astounding things 
 of life. ^ ^ ^ 
 
 And now let me lay before you the final and crushing proofs of 
 the utter futility and fallacy of this theory. 
 
 What is the origin of those physical characteristics that are called 
 temperamental? You have on the screen pictures from life in which 
 are represented the three great races from which it is believed all the 
 modern peoples of the earth have arisen. The black race is represent- 
 ed by the South African Medicine Man; the yellow Mongolian race 
 by the group of Chinese; and the Caucasian peoples by the blue-eyed 
 ISTorwegian bride. The three distinct types of skulls, long, broad and 
 medium, most characteristic of distinct races, are also represented in 
 these three types. 
 
 Away back in neolithic, or even in paleolithic times, there were 
 two races in Europe — the long-headed or dolichocephalic type, and 
 the broad or round heads, the brachycephalic type.*' 
 
 ''Professor Duckworth, of Cambridge, England, writing of the Krapina skull, says: "It is 
 shown that early paleolithic man presents examples of skulls both of brachy-cephalic and 
 dolicho-cephalic proportions." 
 
 12 
 
"A ^EW Classification of Tooth Foems" 
 
 The Caucasian race is, possibly, a later evolutionarj development. 
 
 The portraits I have just shown may be taken as the modern 
 representatives of those ancient races. Broadly speaking, the fair 
 races, and, to a large extent, the yellow races, are found in ISTorthern 
 and Central Europe and Asia, while the darker races occupy the 
 Equatorial and southern regions. From the mingling of those light 
 and dark races, the working of the principle of variation, and the modi- 
 fying effects of climate and general environment, there has arisen all 
 the racial or temperamental characters that the widely varied inhabi- 
 tants of the earth exhibit. 
 
 There are many theories and there is much speculation about these 
 ancient races, but all theories and all known facts are in agreement 
 on the point of the meeting and mixing of dolichocephalic and brachy- 
 cephalic races in Europe in prehistoric times. 
 
 It is a very fascinating theme, but we cannot dwell upon it now, 
 and the main facts are all that is necessary to our purpose in tracing 
 the origin of temperament. What we really know beyond controversy 
 is that everything denoted by the term temperament must have arisen 
 in or originated from race. We can see clearly enough that most of 
 the peculiarities described as sanguine must have been transmitted by 
 the Caucasian race, while the bilious features were inherited from the 
 dark races, and the Mongols have most of the distinctive traits called 
 "lymphatic." 
 
 '^ '^ '^ 
 
 If we now open a book such as Stewart's on "Our Temperaments," 
 the latest and best work on the subject that I have seen, and find 
 portraits of such individuals as those now shown on the screen, we 
 know that the physical or so-called temperamental characters which 
 they present did not arise spontaneously and without cause. The im- 
 mediate ancestors of that man with red hair and blue eyes were not 
 natives of Africa. The parents of that swarthy individual with dark 
 complexion and black eyes and hair were not full blooded Swedes or 
 I^orwegians; and we can predict with reasonable certainty that there 
 is a Mongolian strain in that so-called lymphatic person with the 
 pipe who looks so comfortable and altogether satisfied with himself. 
 In other words, we can discover no special trait or characteristic in 
 these individuals who are supposed to be representative of the differ- 
 ent temperaments, that is not even more clearly shown in the repre- 
 sentatives of the great races which were exhibited a moment ago. In 
 fact, the only difference is that these temperamental types are further 
 removed, by crossing, from their racial origin. The real significance 
 of the term "pure temperamental" is that the individual instance 
 
 13 
 
J. Leon Williams, D.D.S. 
 
 shows, in a mixed race, an unusual reversion to the dominant racial 
 type. The mixed temperaments are simply the result of the mingling 
 of the blood of different races, somewhat modified, in the event of mi- 
 gTation, by changed environment. 
 
 If, therefore, there is such a thing as a sanguine type of tooth 
 or a bilious type of tooth, they must have originated in the sanguine 
 and bilious races. If there are special, characteristic, temperamental 
 forms of teeth, there must have been racial forms from which they 
 were derived. There is no possibility of evading the logic of that 
 conclusion. And I think it has always been assumed by our profession 
 that there are racial forms of teeth. I thinlc you will find many refer- 
 ences in our literature to this supposed fact. 
 
 Now, a racial form of tooth must mean a distinctive form pecul- 
 iar to a race. But if I am able to show you that there is no such 
 thing as a racial form of tooth, if I can prove beyond all possibility 
 of doubt that there are certain primary forms of teeth which are, 
 in their general type characteristics, common to all races, light and 
 dark, ancient and modern, savage and civilized, then I submit that 
 even the unreasonable minority will have to agree that all belief in 
 a temperamental type of tooth must go. 
 
 There are certain differences as to size and small differences in 
 proportion of width to length in teeth of the same general type in 
 different races, but as to essential differences in type, there are none. 
 
 ^ ^ ^ 
 
 When I began my work of investigating the forms of human 
 teeth at the Eoyal College of Surgeons, in London, it was with the 
 belief that there were racial types of teeth. I had no doubt about it. 
 I had so often seen statements to that effect that I simply assumed 
 that it was true.^ And when I did not succeed in finding any form of 
 tooth characteristic of race I concluded that my failure was due to 
 race admixture. Even with the most sincere desire and the strongest 
 determination to find out the truth, still what we have been taught, 
 our inherited beliefs, will continue to haunt us for a long time, like 
 unhappy ghosts who see their continued existence endangered and fight 
 for it with all their might. I pursued this study for nearly a year, 
 and during that time I was accumulating a great store of individual 
 human teeth. The largest lot that reached me from any one source 
 
 "I had particularly expected to find strongly marked differences between the teeth of the 
 dolichocephalic skulls of the peoples descended from the Aryan stock and those of the 
 brachycephalic skulls representing the ancient Mongolian races. I also expected to find that 
 the teeth of remote insular groups, such as the Andamans, Fijians and Tasmanians, would 
 present strongly marked typal features. 
 
 14 
 
"A !N"ew Classificatioit of Tooth Forms" 
 
 came from tlie University of Pittsburgli by the kindness of Profes- 
 sor Friesell. But for this interest and generous action on his part I 
 doubt if the discovery I am about to lay before you would have been 
 made. One day it occurred to me that it v^ould be a good idea to 
 begin sorting and arranging the central incisors into groups. (I had 
 long seen that these were the most characteristic of human teeth.) As 
 I proceeded in the work it became evident, after a time, that I was 
 accumulating three very strongly marked groups with a larger num- 
 ber partaking more or less of the combined features of those three 
 groups, but generally with the features of one or other of the three 
 groups dominant in every individual tooth. When I had finished ar- 
 ranging my incisors in this way I again went to the Museum of the 
 Eoyal College of Surgeons to see what light this discovery would 
 throw on further study there. I w^as more than a little surprised to 
 find these three types of teeth in almost every group of skulls which 
 contained a dozen, or even less, with the incisor teeth intact. My long 
 search for something fundamental had been rewarded. I had at last 
 got what I was after — the key to tooth form. All along I had seen 
 that there were different types of teeth in all the different races, but 
 the co-relation of these different forms had never struck me until I 
 went there with the knowledge of what to look for. That is generally 
 the way with all discovery. We walk unsuspectingly over gold mines 
 and oil wells if we do not know how to look for them. When I saw 
 clearly that these three types of teeth existed in all races, I knew 
 instantly that I had got Nature's secret of design in human teeth, 
 and I knew that it would now be possible to beat her in her own work ; 
 for jSTature, working more or less blindly, makes endless mistakes, 
 as I have previously indicated, while we, working intelligently, can 
 avoid those mistakes. I saw that the existence of three types of teeth 
 was the fundamental fact in human tooth form and that every con- 
 ceivable form of human tooth could be evolved from those three types, 
 and I knew that it would be possible to design beautiful and anatomi- 
 cally correct forms of teeth if I ever saw a human tooth again. 
 
 ^ t^ t^ 
 
 Let us now examine in detail the proofs of the statements that 
 JSTature produced three typal forms of teeth in all races and modeled 
 all teeth upon these three. You have on the screen a photograph 
 (Illustration ISo. 6) representing a small but representative selection of 
 the three primary forms or types of human teeth. In all reference to 
 them they will be designated as Class I, II, and III. Class I is character- 
 ized by the parallel or nearly parallel lines which represent the proximal 
 
 15 
 
J. Leon Williams, D.D.S. 
 
 surfaces of these teeth for half or more than half of their length from 
 their incisal edges. In Class II these lines converge so markedly that 
 they would meet in most instances, at a point near the end of the root. 
 These converging lines are sometimes nearly straight, but usually 
 there is a very slight convexity of the mesio-proximal surface and a 
 slight concavity of the distal surface. Class III, which I regard as 
 the most beautiful form of human teeth, and which has rarely if ever 
 before been used as a model for artificial teeth, is characterized by a 
 delicate double-curved line on its disto-proximal surface and some- 
 times, though less frequently, on the mesial surface. All of the sur- 
 faces and angles of teeth of this class are more rounded and graceful 
 than in either of the other two classes. The specimens shown in this 
 photograph represent the most severe or typal shapes of what I call 
 the primitive forms of human teeth. My reason for the use of the 
 word "primitive" will appear later. All of the other teeth in any 
 given set partake of the features of the central incisors but to a much 
 less marked degree. But in this respect the natural teeth of a given 
 set are not always in harmony. The crossing of races or some other 
 cause often disturbs the perfect harmony of line of the different teeth 
 in a set, and you may sometimes find centrals of one class and laterals 
 and canines of another. But usually the harmony is more or less 
 perfectly preserved. In designing artificial teeth we can, of course, 
 always maintain a proper harmony throughout and thus improve on 
 IN^ature. The succeeding photographs will show you laterals (Illustra- 
 tion 'No. T) and canines arranged in the order of the three classes. As 
 I have intimated, the class characteristics are not so marked in these 
 teeth as in the centrals, but you will have no diSiculty in seeing in any of 
 the groups something of the special features of each type. In this 
 photograph you see the effects of crossing the types. There is more 
 or less blending of the primitive forms, although in nearly every in- 
 stance the dominance of one type or another can be perceived. Prob- 
 ably the majority of teeth in all mixed races are of this character. 
 
 •^ 'ife ««fe 
 
 We wiU now pasS to an examination of the teeth of some of the 
 more important civilized and savage races of ancient and modern 
 times, in which I shall show you that the three types or classes of 
 teeth I have illustrated and described are to be seen in the skulls of 
 all these otherwise widely divergent peoples. In this first exhibit, 
 the skulls will all be shown in groups of three, thus presenting in one 
 view the three primitive forms of teeth in each race. We will begin 
 ^ith three skulls from a savage race of to-day — the Sandwich Islanders 
 
 16 
 

 Illustration No. 6 
 Three classes of centrals. Class I upper row; Class II middle row; Class III lower row 
 
 
 Illustration No. 7. Three classes of laterals. Arranged like centrals above 
 
"A ISTew Classification of Tooth Forms" 
 
 (Ulustration ISTo. 8). The shape of the skulls differ markedly, but this 
 difference in skull shape has no necessary relation to the different forms 
 of teeth. We have here the three primary forms of human teeth very 
 clearly shown. We have the square tooth with parallel sides in skull ]^o. 
 1, the pyramidal shaped tooth with its converging lines in JSTo. 2, and 
 an ideal specimen of Class III, with its beautiful curves in skull No. 
 3. 
 
 As you would expect, not all of the teeth in the different groups 
 of skulls which I shall exhibit are such perfect examples of the severer 
 forms of the three classes. Probably perfect examples could always 
 be found if one had a sufficiently large number of skulls at command. 
 The surprising thing is that even in a small collection of skulls, often 
 less than a dozen, I have always been able to find fairly good represen- 
 tatives of the three classes, but I believe that the more severe typal 
 forms are more frequently found in those races in which there has 
 been the least crossing. 
 
 The next view* is of three Javanese skulls.^ Here the centrals in 
 Class III have been slightly modified toward the oval form: Class II 
 is well represented by the pyramidal shaped teeth in skull ISTo. 2, and 
 'No. 1 shows a very good example of Class I. 
 
 Here we have three skulls from another ancient civilized race — 
 the Chinese. No. 1 shows a slightly modified form of the typal tooth, 
 but ISTos. 2 and 3 are excellent representatives of their respective 
 classes. 
 
 «<fe *% -^ 
 
 The next group shows two skulls of the modern German. I was 
 unable, in the small collection of skulls at my command, to find a 
 good example of No. 3 in this series. It should be said that the photo- 
 graphs, in many instances, do not show the characteristics of the dif- 
 ferent forms of teeth as clearly as they would be seen in handling the 
 skulls. 
 
 Three modern Greek skulls are shown in this view — 1 and 2 — 
 very good examples of their class, ]^o. 3 somewhat modified in the 
 direction of 2, 
 
 Skulls of modern Hindoos — all excellent specimens of their re- 
 spective types. 
 
 Three strongly marked forms of Patagonian teeth — l^o. 1 very 
 slightly modified toward the oval shape; ITo. 2 typical and ISTo. 3 an 
 interesting modification in which the line of double curve appears on 
 both mesial and distal surface. 
 
 *It is not possible to reproduce here all the slides shown. 
 
 ^I do not think that these skulls represent the true aboriginal natives of Java. They 
 are probably those of a mixed race. 
 
 17 
 
J. Leon Williams, D.D.S. 
 
 A group from the New Hebrides. IsTos. 2 and 3 are perfect ex- 
 amples of their classes, while No. 1 is slightly modified in the direc- 
 tion of Class III. Notice the wide divergence in shape of these skulls. 
 
 These are three Spanish skulls. I had a rather poor collection 
 to select from in this group. But they are interesting in their way. 
 They all represent modifications of the three primitive forms of teeth 
 and might be called secondary types with the primary form dominant 
 in each specimen. No. 3 is especially interesting as it represents a 
 form of tooth of decided character frequently met with. The con- 
 verging lines of the type are somewhat rounded or curved, the mesial 
 line always more sloping than the distal. There is nearly always slight 
 overlapping with this form of central. 
 
 French skulls. Classes II and III well represented. Class I shows a 
 coarse modification of the typal form. 
 
 These three from the West coast of Africa — all fine characteristic 
 examples, although No. 3 is somewhat marred by the filing of the 
 centrals. 
 
 Three specimens from Italy. Nos. 1 and 3 typical. No. 2 modi- 
 fied. 
 
 A group from the Fiji Islands (Illustration No. 9). Please observe 
 that when the teeth are not all good examples of the primary forms of 
 their class, yet the variation in form is so great as to completely upset 
 the theory of a racial type of tooth. 
 
 Two Kaffir skulls. Perfect examples of classes. The next two 
 and three groups of skulls are, in some ways, the most interesting in 
 the entire collection shown you to-night. The natives of Australia 
 (Illustration No. 10), Tasmania (Illustration No. 11) and New South 
 Wales represent the lowest type of human beings of modern times. The 
 skulls of these savages have many points of resemblance to the Anthro- 
 poid Apes. Here, if anywhere, you might expect to find a racial form 
 of tooth. But just observe the difference in the shape of these skulls and 
 teeth. With the exception of the teeth of the ancient Egyptians, these 
 low Australian savages exhibit the characteristics of the three primitive 
 forms or types of teeth more clearly than any others in the groups 
 I have shown. No. 3 is, I believe, regarded as one of the greatest 
 anatom-ical treasures of the Museum of the Royal College of Sur- 
 geons. It probably shows more intimate relationship with the Anthro- 
 poid Apes than any other modern skull. It was received from Aus- 
 tralia just as I was finishing this work of investigation and was photo- 
 graphed for the first time for me. 
 
 18 
 
Illustration No. 8. Sandwich Islanders, showing three classes of teeth 
 In all the following illustrations, Class I is shown on the left and Class III on the right 
 
 Illustration No. 9. Fiji Islanders — varying tooth forms in same race 
 
"A JSTew Classificatiojst of Tooth Forms" 
 
 The last group in this series that I shall show you (Illustration 
 ISTo. 12) is from that very interesting ancient race, the Egyptians of the 
 III and TV dynasties — a period dating more than 2,000 years before 
 Moses led the Children of Israel out of Egypt. We are back in the 
 Bronze Age at the dawn of what we call civilization, the time of the 
 Troy of the Iliad and before the Great Pyramid was built. It was a piece 
 of great good fortune to have found three such perfect skulls from this 
 far distant era, showing so perfectly the three primary types of teeth. 
 They are each ideal specimens of their class. The teeth in skull IsTo. 
 1 answer perfectly to the description given in our text books of the 
 sangTiine type of tooth, but I believe all authorities are agreed that 
 those ancient Egyptians did not have light hair or blue eyes or a 
 ruddy, light skin. There is evidently a mistake somewhere — perhaps 
 it is the fault of the Egyptians. But the forms of teeth shown in the 
 other two skulls have never been observed by any advocate of the 
 temperamental theory of classification. ]^ew temperaments will have 
 to be invented for them. 
 
 Suppose the teeth in all three of these skulls had been, as might 
 easily have happened, of type I, a strong tooth full of character. Would 
 it not have been said that here was the typical racial tooth form of 
 the ancient Egyptians ? This mistake concerning racial types of teeth 
 has gTown out of insufficient critical observation. 
 
 '^ '^ '^ 
 
 I think a little diversion from our main theme, just to relieve the 
 mental tension for a moment, may be acceptable. The most of you 
 probably know that these ancient Egyptian kings had what you might 
 call supplementary names — a sacred name, and also, at least, some- 
 times, a name taken or given them for some accomplishment and 
 characteristic quality. ISTow the name of one of the kings of the period 
 represented by these skulls was Sneferu or Snefru. According to 
 one eminent authority the English interpretation of his sacred name 
 was "he who makes good." That expression, you see, is not quite so 
 modern as you may have thought it. And Snefru also had another 
 name bestowed upon him for his prowess in dealing with his enemies. 
 He was known as "the wielder of the big stick" — that expression, too, 
 was not invented yesterday. To prove to you that I am not romanc- 
 ing in this matter I show you a picture of Snefru that is sculptured 
 on the rock walls of the Wady-Maghara near Sinai. There he stands, 
 club in hand, over his fallen foe. 
 
 19 
 
J. Leon Williams, D.D.S. 
 
 To exliibit in another striking way how teeth of the different 
 types or chisses run through all the widely divergent races, I have 
 arranged a few photographs in pairs. The full meaning of what I 
 have to show you will be more vividly presented if 1 exliibit before 
 each group of teeth, portraits of individuals of the race represented 
 by the skulls showing the teeth. You will thus have in mind at the 
 moment a clear picture of the wide divergence of races in which there 
 is a substantial identity of tooth form.* 
 
 And I may as well mention right here that the practical signifi- 
 cance of these facts is that they demonstrate and prove that a system 
 of artificial teeth designed with a knowledge of all the facts about the 
 human teeth is equally suitable for all the races of the earth. It 
 covers the whole held and that has never been done before. 
 
 Our first group is a native of the JSTew Hebrides and a modern 
 Spaniard. At first thought it seems almost incredible that any two 
 individuals of races so far apart in racial characters should have teeth 
 that are practically identical. But the two skulls now sho^vn on the 
 screen prove to you that such is the fact. The centrals and laterals 
 in both are of precisely the same type. 
 
 Hfe «^ '^ 
 
 We have shown here a Hindoo and a Javanese as widely diver- 
 gent in outward appearance as the Spaniard and the New Hebridean. 
 But when we look at the skulls of representatives of these two races 
 we find again identity of tooth form. The teeth of the Javanese are 
 slightly worn, but they are otherwise the same in form and size. 
 
 In this view we have a native Australian and a woman of Ger- 
 many. It is not necessary to call attention to the striking contrast 
 of these faces. 
 
 But what about the teeth in these two examples? You see a 
 striking difference in the size and form of the skull, but the teeth are 
 identical in type — both being fine specimens of Class II. 
 
 A modern Chinese and a Patagonian. 
 
 Here also the teeth in both skulls are of Class II, but in this in- 
 stance those of the Patagonian are slightly larger, the laterals markedly 
 so. 
 
 In these two portraits we probably have as strong a contrast in 
 physiognomy as could be found in any two human races that have ever 
 inhabited our earth. In looking at this portrait of one of the last of 
 the Tasmanians, a race that has only recently become extinct, one 
 cannot fail to be struck with the striking resemblance of the nose and 
 mouth to those same features in the chimpanzee. 
 
 *It is impossible to here reproduce these photographs of individuals. 
 
 20 
 
Illustration No. 10. Natives of Australia 
 
 Illustration No. 11. Natives of Tasmania 
 
 Illustration No. 12. Ancient Egyptians, showing three primary tj'pes of tooth forms 
 
Illustration No. 13 
 
 Eight skulls of unlike size and form. All exhibit teeth of Class III. The form and size ot 
 the teeth bear no relation to the form or size of the skull. 
 
 Nationalities from left to right are: 
 
 Australian, Sandwich Islander, Ancient Egyptian, Kaffir, Chinese, African Savage, New 
 Hebridean, Hindoo. 
 
"A New CLASsiFiCATioisr or Tooth Forms" 
 
 But wlien we look at the skulls from these two races we see that 
 in the teeth all contrast has disappeared. Here, indeed, we have the 
 one physical touch of l^ature that makes the whole world not only 
 akin, but of one family. I shall have time to show you but one more 
 illustration of the identity of tooth form in different races, but in this 
 group I will give three examples — a Kaffir, an Egyptian and a native 
 of the Sandwich Islands. 
 
 You see a striking difference in size and shape of skull, but identity 
 in type of tooth, and but very little difference in size. 
 
 Let me now call your attention to two views which present a still 
 stronger proof of the fallacy of the racial type theory. 
 
 You have on the screen a photograph of eight skulls (Illustration 
 "No. 13), representing eight different races as different in physiognomy, 
 ^hape and size of skull and general race characters as it is possible to find. 
 The central incisors are all of one type — Class III — the form of tooth 
 that has never before been observed. In this next view you have nine 
 more skulls (Illustration ISTo. 14), all from different races, and in these 
 you have another distinct type of tooth, that of Class I with slight varia- 
 tions, and this form also, you see is common to all the races. 
 
 While the view of a considerable number of skulls is before you 
 I will once more ask you to note the fact mentioned several times, 
 during the course of this lecture, that ]N"ature does not always produce 
 a definite type of tooth for any given form of skull. 
 
 *% '^ *<& 
 
 During life, the individuals which these skulls represent must 
 have presented a great variety of facial contours. But observe how 
 many of the central incisors in these widely varying skulls are alike or 
 nearly so. Look at that upper row of four skulls. The teeth are 
 identical in type and nearly so in size. But what a contrast in the 
 skulls, especially in 1448 and 398, and again you see the smaller skuU 
 has slightly larger teeth. 
 
 Some of you may be thinking that I specially selected these speci- 
 mens from a very large collection of skulls. But I did not ; I took what I 
 already had in hand for other purposes. They are simply different 
 groupings of those which were first shown on the screen. 
 
 Again I say the proof that Nature produces no perfect harmonies 
 of relationship in the different parts of organisms is to be seen on 
 every hand. It is before our eyes all the time. 
 
 In bringing forward so many of these contradictions of Nature, 
 I may seem to be introducing an unnecessary confusion. But what I 
 am really trying to do is to bring order out of confusion. And in any 
 
 21 
 
J. Leon Williams, D.D.S. 
 
 event I think it is always much better to know and face all of the 
 important facts in any problem, but I hope no one will take the demon- 
 strations and facts I have just presented as warranting the conclusion 
 that natural teeth are always so imperfectly adapted to face and fea- 
 tures, that this relationship may be neglected. That would be as far 
 from the truth as the assumption that l^Tature always produces a per- 
 fect harmony between teeth and face. The important point which 
 contains the gist of the whole matter is simply this: there is such a 
 considerable minority of cases in all mixed races, especially in all 
 widely divergent races in which crossing has recently occurred, in 
 which there is more or less disharmony in the relation of features, 
 that it would be a disastrous mistake either to found a system of arti- 
 ficial teeth on the assumption that all natural teeth are in harmony 
 with the organism, or to conclude that in edentulous cases no improve- 
 ment over the natural teeth which the patient had is ever possible. 
 
 More than that, I will say that anyone who wall take the trouble 
 to examine and compare forty or fifty skulls from almost any race will 
 be forced to the conclusion that if he wishes to follow Nature blindly 
 in the matter of adapting teeth to facial contour he has a fairly wide 
 range of choice in making his selection. It would probably express 
 an important truth to say that ligature seems to be always striving to 
 reach or realize harmony, but rarely achieving a perfect success, and 
 sometimes going very wide of the mark. The great variety of incon- 
 sistencies in J^ature emphasizes in a most striking manner the para- 
 mount importance of finding some fixed principle of harmony between 
 tooth form and facial contour. Art must supply us with that which 
 Nature has failed to give us. What we have to do is to study closely 
 the majority of instances in which an approximation to harmony is 
 seen, and from the knowledge thus gained to deduce the general prin- 
 ciples on which the highest possible degree of success may be based. 
 No clear, definite statement of such principles is to be found anywhere 
 in our literature. 
 
 '^ '^ '^ 
 
 The one important fact we have established up to this point is 
 that there are three types of teeth common to all races. 
 
 I have no need to labor this point of identity of tooth form in 
 different races or to press for conclusions in the least, beyond what the 
 facts will fully warrant, but I submit that I have destroyed the last 
 vestige of a belief in a racial type of tooth. And along with the 
 passing of that belief there must disappear also the theory of a tem- 
 peramental type of tooth. My summary of the whole matter is this: 
 
 22 
 
Illustration No. 14 
 
 Nine skulls of different races and unlike size and contour, all with teeth of Class I. The 
 form and size of the teeth bear no relation to the form or size of the skull. 
 
 Nationalities from left to right are: 
 
 Spanish, Sandwich Islanders, New Hebridean, German, Javanese, Hindoo, Fiji Islander, 
 Italian, Ancient Egyptian. 
 
"A [N'ew CiiAssiFiCATioisr OP Tooth Tokms" 
 
 That as a working theory it has always been so vague in statement and 
 indeterminate in application that it has never taken any serious hold 
 upon dentists and is practically a dead letter with more than nine- 
 tenths of the profession; that to teach a theory which no one really 
 practices or understands is immoral, because it leads directly to a 
 disbelief in any scientific basis for prosthetic dentistry; that if there 
 had ever been any real desire to undertake a practical application of 
 the theory it would not have been possible to do so because no manu- 
 facturer of artificial teeth has ever made any successful attempt to 
 comply with the demands of the theory; and lastly, that the theory 
 has absolutely no foundation in scientific fact, because it is fully and 
 incontrovertibly demonstrated that any given forms of teeth are not 
 peculiar to any race, neither do they bear any necessary relation to 
 the shapes or sizes of skulls. In all races there is community o£ typal 
 tooth form. Small variations in size and small variations in propor- 
 tion of width to length there certainly are in the teeth of different 
 races, but the three types or classes are present and distinct in all the 
 races I have examined. In fact, one of the most interesting things to 
 me in the course of this investigation has been to see how the three 
 types everywhere persist through the small variations observable in 
 the teeth of different races.® 
 
 '^ *<& *% 
 
 Although just a little aside from our main subject, I think it will 
 interest you to have a glance at a few prehistoric skulls (Illustration ^o. 
 16). The three now shown, reading from your left to your right, are 
 known to anthropologists as the man of La-Chapelle-aux-Saints, a typical 
 skull of the very ancient J^eanderthal race, the Coombe Capelle man, 
 representing the Aurignacian race, and the "old man of Cro-Magnon," a 
 representative of the race of the same name. Their estimated ages 
 range from 25,000 to 150,000 years. I believe no prehistoric skull 
 has been discovered with an over bite of the upper incisors. The two 
 shown on the right, you see, have the edge-to-edge bite. The third 
 one, the man of La-Chapelle-aux-Saints, must have been a very aston- 
 ishing and savage looking creature with a very projecting muzzle, huge, 
 flat nose, enormous eye sockets and heavy supra-orbital ridges. Ob- 
 serve that his teeth were nearly all lost from loosening and decay. 
 This skull is also from the Cro-Mag-non race. ISTotice the great depth 
 of the lower jaw and the size of the central incisors, which are fine 
 
 ^Keane, in his table of Ethnology, describes the teeth of the negro races as large (macro- 
 dont), those of the Mongols and native Americans as medium (mesodont) and the Caucasian 
 teeth as small (microdont). But the teeth of the mixed races range through all these sizes. 
 
 23 
 
J. Leon Williams, D.D.S. 
 
 specimens of Class I. I have another skull of the same race in which 
 the teeth are of a totally different type — approaching Class III — with 
 rather small and very beautifully modeled teeth. 
 
 The next slide and the following one* show a peculiarity or a 
 specialization of the teeth of the Xeanderthal race, which enables us 
 to recognize this ancient people whenever teeth of this type are dis- 
 covered. This peculiarity is twofold — fusion of the roots and enor- 
 mous size of pulp cavity. 
 
 This photograph shows the efforts of three different artists, all 
 trained anthropologists, to represent different types of prehistoric races. 
 
 Let me now call your attention to another discovery I have made, 
 in relation to what has already been shown, that is not only interest- 
 ing to us as dentists, but has also proved to be of deep interest to 
 anthropologists and workers in other scientific fields. The significance 
 of this discovery is that it traces the origin of these three types of teeth 
 back to a time antecedent to the advent of humanity. When I had 
 made thorough examination of the teeth of the lowest and most primi- 
 tive races, finding everywhere the three distinct forms, it occurred 
 to me one day that the teeth of the anthropoid apes might throw some 
 light on this question of origin of types. You now have on the screen 
 a photograph (Illustration ISTo. 16) of three skulls of the orang-outang. 
 I have selected these as representing the group of anthropoid apes be- 
 cause the teeth in these three skulls were the most unworn and perfect 
 available at the moment, but the facts are the same with reference to 
 the gorilla (Illustration jSJ'o. 17) and the chimpanzee (Illustration 'No. 
 18). 
 
 «% '^ <^ 
 
 You will observe that we have here the three types of teeth that 
 we have seen in all the races shown, but, as you would expect, the 
 characteristics of each are rather more strongly marked than in the 
 genus Homo. You have the central incisor with parallel sides, the- 
 representative of Class I, the incisor with sharply converging sides of 
 Class II, and the one with the fine double curve on its distal side and 
 the generally rounded form which is the special feature of Class III. 
 If there is any temperamental sig-nificance in these forms of teeth in 
 the anthropoid apes, I should be glad to have it pointed out. 
 
 Another very significant fact in this connection is that in the 
 anthropoid apes the variation in the proportion of width to length 
 of the central incisors in Class I is very marked, some being very 
 short and others very long, while in the other t^vo classes this varia- 
 tion is very slight. Exactly the same thing is true of himian teeth. 
 
 'These illustrations are not available for use at the time this book goes to press. 
 
 24 
 
Illustration No. 13. Prehistoric skulls. Xeander that at the left 
 
"A 'New Classificatiojst of Tooth Foems" 
 
 It is for this reason that Class I, in our system, has a series of three 
 lengths with five sizes to each length, while the forms in the other 
 two classes are produced in series of sizes only, or with but slight 
 variation in proportion of width to length. 
 
 Whatever the ancestral form may be from which man and the 
 anthropoid apes have descended, or ascended, it is plain that we have 
 here one of the most striking homologies that has been discovered. It 
 is an especially interesting evidence of relationship because it is one 
 of Owen's classical examples of homology and analogy.^° 
 
 The teeth are still functional in both man and the apes. It is 
 clear, therefore, that the origin of the three types of human teeth can 
 be traced back into what the old-fashioned orator was fond of refer- 
 ring to as "the dim mists of antiquity." We have reached something 
 fundamental here that is of very great importance in our work. Man 
 has three types of teeth because they have been bequeathed to him 
 from his simian ancestors, just as he has five fingers and five toes, be- 
 cause they have been passed on to him from the early amphibians. 
 You now understand why I call the three severe types or classes of 
 human teeth the "primitive" forms. 
 
 '^ '^ '^ 
 
 It may interest you to know that this discovery of the funda- 
 mental types of teeth in man and the anthropoid apes as shown in, 
 these photographs, has been submitted to quite a number of the fore- 
 most scientific men of the United States and Europe, among whom 
 I may mention Prof. Henry Fairfield Osborn, President of the Amer- 
 ican Museum of ISTatural History, Professor Schafer of Edinburgh, 
 President of the British Association of Science for 1912; Professor 
 Keith, Hunterian Lecturer at the Poyal College of Surgeons, and 
 author of "Types of Ancient Man" ; Dr. Woodward, of the ISTatural 
 History Museum, South Kensington; Dr. A. Russell Wallace, co- 
 discoverer with Darwin of the principle of ISTatural Selection, and 
 Prof. Ernst Haeckel, of the University of Jena, admittedly the great- 
 est authority who has ever lived in matters of comparative morphology 
 in man and the lower animals. It was of Professor Haeckel's great 
 work on morphology that Huxley said: "It is one of the greatest pro- 
 ductions in the history of science." And Darwin said that if he had 
 read Haeckel's "Comparative Morphology" before he began the "De- 
 scent of Man," that book would never have been written. 
 
 ^""The wing of a bird and the wing of a bat; they are both fore-limbs of similar structure 
 and development; they are both organs of true flight; they are at once homologous and analo- 
 gous." — Owen. 
 
 "When two or more structures, organs or specialized parts, in one and the same organism, 
 or in several organisms, show a deep resemblance in their architecture and also in their 
 manner of development, they are said to be homologous. . . . Now, the evolutionary 
 suggestiveness of homologies is indisputable." — Evolution, by Thomson and Geddes. 
 
 25 
 
J. Leon Williams, D.D.S. 
 
 Very interesting comments have been made and no word of criti- 
 cism has been passed on what seems to be the inevitable conclusion of 
 the facts shown in my photographs. But as the discovery was in the 
 field of comparative morphology it was Professor Haeckel's opinion 
 that I particularly desired. 
 
 I think the letter conveying that opinion to me is sufficiently 
 characteristic and interesting to warrant publication. 
 
 He says: 
 
 Jena, 6, 1, 1913. 
 
 Dk. Leon Williams^ 
 London. 
 Dear Sir. — Your observations on the three different types of 
 the upper central incisors are very interesting, and mainly the fact 
 that the same three characteristic types occur also in the orang-outang 
 and in other anthropoid apes. In my opinion this fact is another 
 new and convincing proof for the near relationship between man and 
 the anthropoid apes, and for the phylogenetic theories that both have 
 been derived from one and the same common ancestor. First, the 
 fact that these three types — in physiological relationship of little 
 value — are so distinctly developed in three morphological directions, 
 seems to me an important proof that the way of phylogenetic diver- 
 gence of characters is the same in man and in the anthropoid apes. 
 Very respectfully yours, 
 
 (Signed) Ernst Haekel. 
 
 "With what admirable clearness and conciseness Professor Haeck- 
 el's masterful mind has gone straight to the mark in that letter. 
 Three forms or types of teeth have no special physiological signifi- 
 cance, as he says. One type is as good as another for purposes of 
 mastication. But the morphological meaning conveys the story of 
 man's origin, and so becomes one of the most fundamental facts about 
 human teeth. x\nd on that fundamental fact is established the new 
 classification.^^ 
 
 I have several times intimated during the course of this paper 
 that the makers of artificial teeth have never had any scientific guid- 
 ing principle either for classification or design. Let me finish with 
 that subject now, and I will then take up the constructive part of my 
 work. What have the manufacturers done when they have wished to 
 produce a new pattern of their so-called natural form teeth? They 
 
 ""In connection with the skull, I may speak of the teeth-organs which have a peculiar 
 classificatory value, and whose resemblances and differences of number, form and succession, 
 .taken as a whole, are usually regarded as more trustworthy indicators of affinity than any 
 -others." Man's Place in Nature, Huxley. The italics are mine. 
 
 26 
 
Illustration No. 16. Skulls of orang-outang, showing three primary tooth forms 
 
 Illustration No. 17. Three types in skulls of gorilla 
 
 Illustration No. 18. Chimpanzee Skulls 
 
"A 'N:ew Classification" of Tooth Foems" 
 
 have looked about until tiiej found what they considered a particu- 
 larly attractive looking set of teeth, either in a skull or in the mouth 
 of some living person, and have then copied this set of teeth as well 
 as they could. Well, that work is a long step in advance of the old 
 products of the tooth factories. But for whom are those teeth suit- 
 able in artificial dentures ? On the assumption that in iSTature a set 
 of teeth is in perfect harmony with the face and features, that par- 
 ticular set of teeth could not possibly be in perfect harmony with a 
 different face. But I have called your attention to the fact that should 
 always have been obvious to us, viz., that in ISTature there is rarely 
 more than approximations to harmony and often such a lack of har- 
 mony that the grotesque is suggested.^' 
 
 '^ '^ '^ 
 
 If the set of teeth copied was not in harmony with the skull or 
 the face in which they were found, what suggestion has ever been 
 made for their harmonious use? When the manufacturer wishes to 
 produce another mould he finds another set of teeth, and for a third 
 mould a third set of teeth, and so on, ad infinitum. As the minute 
 variations in natural teeth are probably only limited by the number 
 of people dead and living and to be born, is there any good reason 
 why the manufacturers should not go on to the end of time produc- 
 ing new moulds of teeth? And have they not always acted on that 
 principle ? Have not all the companies in existence been turning out 
 new moulds of teeth steadily for nearly a century? Working accord- 
 ing to their present plan, is there any reason why they should ever 
 stop? What is the relation between the teeth of one manufacturer 
 and another? There is none except when they copy each other's 
 patterns, which they frequently do. ISTor is there any ordered rela- 
 tion between the teeth of any one manufacturer. The end of all this 
 is a chaos of confusion doubly confounded, a vast heterogeneous mass 
 of artificial teeth in which no real artistic principle has been em- 
 bodied. The present method, even at its highest and best, that is to 
 say, when natural teeth are copied as closely as possible, is an artis- 
 tic failure, because a work of art cannot be produced by baldly copy- 
 ing ISTature. 
 
 Let me repeat here and emphasize what I have said in a former 
 paper on this subject, that while all art work must be founded on the 
 most intimate, penetrating and thorough study of Mature that it may 
 be true to life, yet truth to life means much more than an indiscrimi- 
 
 ^In the so-called Natural-form teeth on the market I have noticed that certain natural defects 
 have been copied which make a perfect anatomical occlusion impossible. 
 
 27 
 
J. Leon Williams, D.D.S. 
 
 nate coiisideratiou and acceptauce of a mere welter of facts. It 
 means the appreciation and understanding of the relative value of 
 facts, and the power or faculty of discriminating between what is of 
 small value and what is important, characteristic, relevant, line, all 
 that is really vital to the subject. And that statement fairly intro- 
 duces the whole problem in the constructive part of our work, which 
 we now approach. The heart of that problem is such a thorough 
 mastery of all the facts of Nature as will enable us to know what it 
 is that gives character in our work and what detracts from it; what 
 makes it beautiful or what causes it to look ugly or commonplace. 
 
 Out of the vast confusion and imperfection of Nature we have 
 to isolate, so far as we can, the pure elements of truth and beauty in 
 tooth form, and impress those elements into our service in the work 
 of designing a system of artificial teeth. We have to attempt what 
 every artist undertakes when he seeks to give expression to a more 
 or less ideal conception he has formed after long study and com- 
 munion with ^Nature. 
 
 '^ -^ *% 
 
 When that little group of French artists known as ''The Bar- 
 bizon School" were living together on the borders of the forest of 
 Fontainebleu, someone asked Millais one day which tree he thought 
 the most beautiful, from the artistic point of view. After a few mo- 
 ments' consideration, he replied: "The one that is in harmony with 
 its surroundings." A fundamental principle in art was never more 
 finely stated. Exactly the same language may be used to express the 
 relationship between tooth form and face. That tooth is most beau- 
 tiful for any face which is in most perfect harmony with it. Very 
 well, then we have to determine, if we can, just what it is that con- 
 stitutes this harmony. Is it entirely a matter of taste and individual 
 judgment, or is there a principle involved which may be demonstrated 
 so that all may see and benefit by it ? 
 
 Here, as always, we must go to ISTature, not to copy baldly every- 
 thing that we find, but to discover the essential thing. Everyone 
 who has had any experience in this field knows that if he were to 
 place a set of oval teeth in the mouth of a person who had a very 
 square face, or a set of long teeth in a very short face, the dishar- 
 mony or falseness would be glaringly evident. Even the novice in 
 dentistry would almost instinctively select a square tooth for a square 
 face, and a short tooth for a short face. But why are the straight 
 lines of a square tooth in harmony with a square face, and the curved 
 lines of an oval tooth in harmony with an oval face ? If we can dem- 
 
 28 
 
"A IsTew Classification of Tooth Eoems" 
 
 onstrate the application of a principle in an obvions case, then we 
 may also he able to apply it when the conditions are somewhat more 
 complex or obscure. I can hardly repeat too frequently that the whole 
 problem is purely an art problem, because that very important fact 
 has never been sufficiently recognized. ISTow, in all works of art, 
 whether of drawing, painting, sculpture or architecture, harmony or 
 balance is secured in two ways, or by the application of two rules — 
 by parallelism and by opposition of line and curve, and usually by 
 the combination of the two. Excluding color for the moment, that 
 is the most fundamental thing in all art work. The severe, classic 
 beauty of a Greek temple is secured almost wholly by the parallel lines 
 of the columns, which are not quite parallel or quite straight. And 
 those upward shooting lines also constitute the chief element of beauty 
 in the more ornate Gothic cathedral of later times. The beauty of 
 the Apollo Belvedere or the Venus de Milo is entirely founded on 
 the balance or opposition of curved lines, and a painting by Turner 
 or Claude or any other great master owes its artistic merits, so far 
 as composition is involved, entirely to the balance of both straight 
 and curved lines. 
 
 -^ '^ -^ 
 
 The principal laws of harmony in all art work involving out- 
 line may be briefly stated as follows: Lines that are parallel or 
 nearly so are harmonious; lines that converge or diverge must have 
 other lines, shorter or less in number, set in opposition to them to 
 produce harmony. Curved lines running in a similar direction are 
 harmonious, but branching or diverging curved lines also require 
 opposition lines to complete their harmony. 
 
 Those laws or rules are just as applicable to the designing and 
 use of artificial teeth as to building a temple or carving a statue. 
 They are the only rules by means of which a high degree of success 
 may be reached in the adaptation of tooth form to facial contour, and 
 their application is perfectly simple and free from ambiguity, as we 
 shall see presently. 
 
 During all the time that I was laying before you proofs of the 
 fallacy of the theory of temperamental tooth form, of the theory of 
 racial tooth forms, of the idea that jSTature always produces harmoni- 
 ous tooth forms, and the notion that the way to produce a system, or 
 rather, the absence of a system, in the making of artificial teeth is to 
 copy natural sets of teeth — while I was presenting all of those proofs, 
 I was, at the same time, by use of the facts those proofs contain, 
 building up a system of classification founded not on imaginary dis- 
 
 29 
 
J. Leon Williaims, D.D.S. 
 
 tinctions but on scientific realities. The facts that disprove the tem- 
 peramental theory are the facts on which the new classification is 
 based. 
 
 We are now in a position to gather np the somewhat scattered 
 threads of our proofs and arguments and to show their true signifi- 
 cance in the real work of desig-ning a new system of artificial teeth. 
 As a solid basis for that, we have established a new classification for 
 natural teeth in the three primitive forms shown and the secondary 
 and other forms produced by the crossing of these primary forms. 
 
 In those three primary forms of teeth we have all the elements of 
 design necessary for producing an indefinite number of varieties of 
 artificial teeth. But an indefinite number are not required. On the 
 contrary, we require comparatively few forms, for the reason that 
 there are but few types of human faces. 
 
 Referring, as I understood, to this subject, one of the eminent 
 gentlemen who discussed the paper which I read here in December, 
 expressed the opinion that perhaps the last word in artificial teeth 
 had not yet been said. Well, heaven forfend that the last word on 
 any subject be said by us. That would leave our successors in the 
 unenviable position of having nothing to say. 
 
 •^ '^ '^ 
 
 But let us examine, a little, that expression "the last word" with 
 reference to certain phases of the Trubyte System of teeth. What is 
 the distinguishing feature of this new system ? The forms of the teeth 
 and the fundamental, scientific principles on which they have been 
 worked out? While the "last word" can never be said on any sub- 
 ject, yet you have all heard of ultimate facts in nature. These ulti- 
 mate facts, once discovered, remain ultimate facts forever. More may 
 be learned about the far reaching significance of these facts, but noth- 
 ing can ever be learned which will upset them or in any way change 
 their essential meaning. 
 
 The law of gravitation is an ultimate fact of nature. The turn- 
 ing of the earth on its axis is another. We may go on forever learn- 
 ing more about these great truths, but no further discovery will ever 
 change the essential fact. ISTow in form in nature there are certain 
 ultimate facts. The square is one, the equilateral triangle is another 
 and the circle is a third. You can never get anything more square 
 than an area bounded by four equal sides, the four corners of which 
 are right angles. 
 
 You can never get anything more round than an area described 
 by a line every point of which is equidistant from a fixed center. These 
 
 30 
 
"A ITew Classification of Tooth Tokms" 
 
 are ultimate facts. So this discovery which I have made of three 
 primary forms of teeth is one of those ultimate facts of nature. That 
 form of central incisor which approaches most closely to the square 
 must always stand as the typal tooth in that class, and that form 
 which has the straightest and most converging lines and a section of 
 which consequently most closely approximates an equilateral triangle 
 must, necessarily, always stand as the typal form in Class II. Like- 
 wise that tooth in Class III, which embodies most of the elements of 
 the circle will always be the representative typal tooth in that class. 
 I submit that there is no getting away from the logic of that proposition. 
 
 Illustration No. 19 
 The three simple forms from which all other forms are made 
 
 If anyone can find a squarer tooth or a more pyramidal-shaped 
 tooth or a tooth with more marked curves in its proximal lines than 
 those I have exhibited as specimens of the three classes, he will not 
 injure my discovery or the classification founded on it. On the con- 
 trary, he will further confirm and make it more positive. So far, 
 then, as the classification of human teeth is concerned, this is the last 
 word in the sense that it is a statement of ultimate facts, and the 
 designing of artificial teeth for all future time must be based on those 
 ultimate facts. When the mind has once grasped an essential truth 
 it can never let go of it. Other manufacturers may bring out teeth 
 shaped like those in the Trubyte System without attempting to classify 
 them, but just to the extent that they are not classified they will be 
 
 31 
 
J. Leon Williams, D.D.S. 
 
 inconvenient for the dealer to handle and the dentist to select and 
 order. To produce artificial teeth on any other than the three-form 
 basis is to present the play of Hamlet with Hamlet left out. 
 
 '^ '^ '^ 
 
 In the elements of design we have in the three primary types of 
 natural teeth, we see what a perfect means we have for producing 
 artificial teeth of all forms necessary for the most complete harmonious 
 relations with every type of human face. When we come to analyze 
 these elements of design, we find that they are very simple, but, as I 
 have said, capable of an indefinite number of beautiful combinations. 
 
 Illustration No. 20 
 Elements of design, separated 
 
 You have on the screen a picture of these elements of design, 
 separated or analyzed as a few curved and straight lines, and combined 
 as one of the typical forms of our classification. Let us see how by 
 slight variations of those few lines we can produce every conceivable 
 form of human tooth — and you will see that we produce our varia- 
 tions after the method of JSTature — by crossing the typical forms. 
 
 I told you in a former paper that all the fundamental principles 
 of art and design could be applied to the making of artificial teeth. 
 Now what does a competent artist do when he has it in mind to design 
 a fine picture? He decides on the subject and general plan of his 
 painting, and then proceeds to make many careful studies of all the 
 elements which are to appear in the finished work. When it comes to 
 the final composition of the picture, he probably makes several trials 
 before he gets that perfect balance of line and mass that satisfies him. 
 
 32 
 
"A l^Ew Classification of Tooth Foems" 
 
 That is precisely the method that has been employed in designing 
 all these forms of teeth. The suggestions for most of the designs have 
 come from natural teeth. The first step has always been to make a 
 number of accurate studies or drawings of the outlines of those nat- 
 ural teeth most closely resembling the intended form. First the cen- 
 trals, then the laterals and canines, and last, the lower incisors are 
 all laid out so that all can be seen at once and compared. There will 
 be some lines that balance, that are harmonious, and others that are 
 discordant. The problem is precisely that of designing a good com- 
 
 Illustration No. 21 
 Elements of design, partly assembled 
 
 position — to secure perfect harmony of line and mass, and that is not 
 an easy matter in so small an object as a tooth. When it comes to the 
 carving, several are sometimes discarded before the satisfactory result 
 is reached. 
 
 '^ '^ '^ 
 
 All variations in the models of artificial teeth designed for the 
 different types of face are produced by slightly varying the curvature 
 and balance of line of those few simple elements of design in accord- 
 ance with the contour of face for which the tooth is designed. But 
 the knowledge of how to do that in the best and most artistic manner 
 possible can only be acquired, as all other artistic knowledge is, by 
 much experiment and by long and concentrated study of human teeth 
 and human faces. 
 
 33 
 
J. Leon Williams, D.D.S. 
 
 The aim, in designing artificial teeth, should always be to main- 
 tain character in the tooth by keeping its typal or class features dom- 
 inant. The most uninteresting and unattractive tooth is one in which 
 the characteristics of all three of the primary types have become so 
 blended that it has no distinction. It is characterless. This whole 
 subject can be illustrated and demonstrated in a few moments by dia- 
 grams or outline drawings. 
 
 Illustration No. 22 shows perfectly accurate outline drawings 
 of specimens of natural teeth of the three primary classes. You will 
 remember that when I was showing the teeth of the orang-outang I 
 called your attention to the great variation in the proportion of width 
 to length shown in the teeth in Class I. The lower row in the view 
 on the screen illustrates this point again, and I will ask you to keep it 
 in mind when I come to describe the system of constructing porcelain 
 teeth. 
 
 Illustration No. 22. Variations in three primary types 
 
 The teeth in the other two rows have all been drawn to the same 
 length, but the proportional width has been preserved. By the cross- 
 ing of these three types, N^ature has produced every form of human 
 tooth that has existed, through all the ages down to the present time. 
 In the very nature of things, some one of those forms or variations will 
 be better adapted to or more harmonious with a given type of face 
 than another. But we have seen that iSTature exercises no very fine 
 discrimination in adapting tooth form to facial contour. That means 
 that the vast majority of her variations in teeth are of no particular 
 artistic value. They can be discarded or ignored so far as a system 
 
 34 
 
"A Nnw Classification of Tooth Forms" 
 
 Illustration No. 23 
 Typal forms numbered. Modifications of those forms by blendings shown beside typal forms. 
 
 E nr. 
 
 lo M. nn, w: 
 
 A< 
 
 A 
 
 (D. 
 
 Illustration No. 24 
 
 35 
 
J. Leon Williams, D.D.S. 
 
 of teeth for edentulous cases is concerned, and the forms that are pro- 
 duced can be far more perfectly adapted to characteristic facial outline 
 than any except the few rare triumphs of Nature. 
 
 '^ '^ '^ 
 
 The facts that I am most desirous of getting clearly before you 
 are that this system is a perfectly natural one, and that all the meth- 
 ods by means of which it has been worked out are no other than such 
 modifications of N^ature's own methods of working as will lead us 
 more directly and quickly to our desired end, and in that end give us 
 more uniformly perfect results than are ever found in Nature. In 
 methods and in results it is a perfected artistic compendium of all of 
 Nature's work in teeth. 
 
 Our position in this matter of design, in relation to one who pro- 
 duces artificial teeth by simply copying natural ones, may very justly 
 be likened to that of the breeder of animals or the producer of new 
 and improved forms of fruit. We are no longer blind followers of 
 Nature, imitating her defects, but intelligent selectors of principles 
 and utilizers of her secret processes. We eliminate defects. We se- 
 cure harmony. The finished results are, in very truth, more natural 
 than any set of natural teeth because harmony is the very first essential 
 of naturalness. We become the master of Nature instead of being her 
 servant. We utilize everything that is vital and significant and elim- 
 inate all that detracts from perfection. Our one aim in all our work 
 is the establishment of harmony between outline or form of tooth and 
 outline of face. And we achieve that by the proper balance and curve 
 of line in the tooth, in relation to the type of face for which it is 
 designed. 
 
 If I state the problem in another way you will see at once that it 
 is so. If the size and contour of a tooth is exactly right for a given 
 face, then the harmony is perfect. But the "contour" of a tooth is 
 only another name for the balance of line and curve in the tooth. If 
 the lines and curves of the tooth balance or are in harmony with the 
 lines and curves of the face, then the highest degree of perfection at- 
 tainable has been reached. And we shall see that there is no difficulty 
 in achieving that perfect result in all edentulous cases. Let us, then, 
 now take up the consideration of the relations of typal tooth forms to 
 
 36 
 
"A ]^EW Classification of Tooth Forms" 
 
 facial contours. And in order to make the application of our new 
 principle perfectly plain, we will begin witli the outline diagrams of the 
 four chief types of faces. (Illustration ISTo. 25.) 
 
 These outline diagrams show only the strong main lines of the 
 faces, and thus we shall be able to see quickly and clearly the relation 
 of tooth form to these lines. 
 
 '^ ««fe ««fe 
 
 All of the best writers that I know on the subject of physiognomy 
 are agreed that there are but three well marked classes or types of 
 human faces — the square, the oval and the tapering. But I think one 
 strong type of face has been overlooked by all writers on the subject. 
 It is the form which shows a greater width below the eyes than above. 
 The whole lower part of the face is round and rather heavy, and the 
 forehead is usually dome-shaped. I call this the ovoid face because 
 it resembles the form of skull to which that name has been given. ISTo 
 form of tooth has ever been made that is well adapted to this shape 
 of face, but those of Class III in our system are perfectly suited to it. 
 These four types of faces have several modifications which we shall 
 consider as we proceed. 
 
 In the square face and in its principal modifications, that is to 
 say, in all faces the sides of which are parallel or nearly so, we secure 
 perfect harmony with the teeth of Class I. 
 
 If the face is typical or severe in its squareness, then we must use 
 teeth the central incisors of which are parallel on their proximal sides. 
 But the great majority of square faces is not of this type. Usually 
 there is a slight converging of the lines from the forehead to the chin, 
 and the teeth should therefore have lines which converge slightly toward 
 the neck.* 
 
 The oval face is the result of a slight rounding of the angles of 
 the square face. Exactly the same modification of the square tooth 
 produces the oval tooth. 
 
 Again, in the ovoid face, our tooth outline follows the general 
 contour of the face. The characteristic of this type of face, you will 
 
 *Iia all that we have to say abotit tooth form, it is always to be understood that we are 
 speaking of the upper central incisors. It is these teeth that are the chief factor in deter- 
 mining harmony with the face, and they also govern the type of all other teeth in the set. 
 
 37 
 
J. Leox WrLUAits, D.D.S. 
 
 Tapering face. 
 
 Ovoid face. 
 
 IDasbation No. 25 
 
 38 
 
'■'A Xe-^ Classiticatiox of Tooth Fokms" 
 
 remember, is the width., ro-andiiess and heaviness of the lower part. 
 This is the special feature of the teeth in Class lU. The general 
 character of the tooth of this class and the flow of all its lines corre- 
 spond perfectly with the ovoid face. In all of the foregoing illustra- 
 tdons harmony is secured by parallelism of tooth outline and face out- 
 line. 
 
 Illustration No. 26. The six upper an:eriors in the three primary forms 
 
 The tapering face has a wider range of variation than any of the 
 other types. It begins as a slight departure from the square face by 
 the convergence of the cheek lines toward the chin and it presents 
 every gradation of change from this to the extreme convergence seen 
 in the very pointed chin. 
 
 In all faces of this character the lines of the proximal surfaces of 
 the upper central incisors run in opposition to the lines of the face. 
 If the lines of the face converge but little toward the chin the proxi- 
 mal lines of the teeth should converge but little toward the neck of the 
 tooth. 
 
 The amount of line convergence in the face governs the amount 
 in the teeth. If this line convergence is accompanied by rather full, 
 round cheeks, then the disto-proximal surface of the upper centrals 
 should also be rounded or convex. In selecting teeth for the tapering 
 
 face of any degTee, you have only one principle to keep in mind, so 
 far as tooth form is concerned, and that is tliat the contour lines of 
 yotir upper incisors must be, in a general way, the reverse of what 
 
 39 
 
J. Leon Williams, D.D.S. 
 
 they are in the face. The obsen-ance of this rule will always give vou 
 perfect harmony — the harmony of opposition of line. 
 
 If I have now made clear the fundamental governing principle 
 in the relation of facial contour to tooth form, we will rapidly pass in 
 review a few photographs of the more striking and distinctive types 
 of faces. (Specimens were shown on the screen.) 
 
 '^ '^ '^ 
 
 We will first examine the forms of teeth best suited to the square 
 face and its immediate modifications, the shorter and longer face of 
 the same type. I am taking these all together in three groups for a 
 special reason. When we were looking at the teeth of the orang- 
 outang you will remember I told you that teeth of the square type, 
 or those with parallel sides, varied more in proportion of width to 
 length than any others, and I added that as the same fact was observ- 
 able in faces I had designed a special series of teeth to meet these 
 conditions. This series is known as Forms 1, 2, 3, 4 and 5 in Class I as 
 now shown on the screen (Illustration Xo. 27). As all of the faces are 
 of the same general type, differing only in proportion of width to length, 
 so the teeth are of one type differing only as the faces do. The teeth are 
 not of the most severe typal form. There is a very slight convergence of 
 the proximal lines and a slight convexity of the disto-proximal surface. 
 The reason for that is that there are but very few faces of the most 
 severe, square, tvpal form and even for these the forms of teeth shown 
 would be perfectly suitable. But there is a very great nimiber and a 
 wide range of faces showing slight modification of the square type. 
 It is to meet that wide range of face found in nearlv all countries 
 that this series of teeth has been designed. There are five sizes to each 
 form, except Form 4, in which the extremely large form is unnecessary. 
 I will ask your close attention for a few moments while I point out to 
 you what it means to have a series of teeth of one model like this. In the 
 first place, there is a very wide range of face in the long, medium and 
 short varieties of the square type for which this series is perfectly suited. 
 But its usefulness and convenience extends much beyond that. You 
 have all had the experience of finding the exact t}^e of tooth you 
 wanted for a given case, but in a larger or smaller size than the case 
 demanded, and you know the feeling it has given you to find that 'the 
 model tooth you wanted was not made in any other size than the one 
 you could not use. Well, that situation can never occur in the system 
 of teeth now suggested. JSTo form will ever be brought out in one 
 size only. That seems to me to be about the most senseless feature 
 that can be charged to the old regime. 
 
 40 
 
"A jSTew Classification of Tooth Foems" 
 CLASS I MOULDS 
 
 (Illustrations show form but not sizes.) 
 
 Form 1. The long modification of the square form. 
 Sizes from small to large from moulds IC, ID, IE, IF, IH. 
 
 Form 2. The medium long modification of the square form. 
 Sizes from small to large from moulds 2C, 2D, 2E, 2F, 2H. 
 
 Form 3. The short modification of the square form. 
 Sizes from small to large from moulds 3C, 3D, 3E, 3F, 3H. 
 
 Form 4. The feminine modification. 
 Sizes from small to large from moulds 4C, 4D, 4E, 4F. 
 
 Form S. Oval modification. 
 Sizes from small to large from moulds 5C, 5D, 5E, SF, 5H. 
 
 Illustration No. 27 
 
 41 
 
J. Leojst Williams, D.D.S. 
 
 Square face — long. 
 Class I, Form 1. 
 
 Square face — long. 
 Class I, Form 1. 
 
 Square face — medium. 
 Class I, Form 2. 
 
 Feminine square. 
 Class I, Form 4. 
 
 Square face — short. 
 Class I, Form 3. 
 
 Oval face, a modification of the square. 
 Class I, Form 5. 
 
 Illustration No. 28 
 
 42 
 
"A JSTew CLAssiFiCATioisr OF Tooth Foems" 
 
 In this particular series we have five sizes in each group, except 
 Form 4, which has four sizes. But there is more than that in it. In all 
 cases for partial plates the absorption following extraction makes it 
 necessary to use a tooth longer than the adjoining natural one, yet you 
 should have a tooth of the same general type. Suppose it is a case in 
 which one central of the short series, iSTo. 3, is missing. The space to 
 be filled demanding a longer tooth of this type, you simply pass from 
 Form 3 to Form 2 and find exactly what you require. If your standing 
 natural central should be of medium length then you pass from 2 to 1 to 
 get what you want. !N'ow, if you will think for a moment what it means 
 to have such a range of selection in a form of tooth for a great variety 
 of the type of face most frequently met, you will, I think, see that 
 this one series of 24 sets is far more valuable for a dentist to 
 keep in stock than twenty times that number of the heterogeneous 
 moulds without system or relation as formerly made, not to mention 
 any of the other very important points of superiority of the new models. 
 
 The short tooth of Form 3 is, of course, for the type of short face, 
 shown in Illustration ISTo. 28. Form 2 is for faces of medium length, 
 and Form 1 is for the long faces. 
 
 The arch of the teeth in the upper jaw of the short and medium 
 square faces is the segment of a larger circle than would be required 
 for any other type of face. There is but little overlap of the upper 
 incisors in this type of face and when the teeth become worn the bite 
 is nearly square, especially in the short face. In the long face there is 
 usually some overlapping of the centrals or laterals. 
 
 -^fe '^ «% 
 
 Illustration 'No. 28 shows the first modification of the square face 
 in the direction of the oval. It is, perhaps, more frequently met with in 
 the United States than in any other form. Teeth of Form 2, Class I, 
 are also perfectly suited for the male face of this type, but for the 
 feminine face I have designed and carved Form 4, Class I. The 
 greatest possible care was given to the modelling of this group of teeth 
 and they have been designed to produce a perfect harmony with one 
 of the finest types of the feminine face in America and England. Slight 
 overlapping of laterals adds to the beauty and naturalness of appear- 
 ance. The general appearance of the arch is the same as in the square 
 face, but is a little more rounded at the front. They have a slight round- 
 ing of the mesial and distal incisal angles. Slight overlapping of the 
 centrals is nearly always found in the finest specimens of natural teeth 
 of this type. 
 
 In the tapering form of face the female type is the most deli- 
 cate, and by many considered the most artistic form of feminine 
 
 43 
 
J. Leon Williams, D.D.S. 
 
 beauty. It is a type of face frequently found in Italy. Women with 
 faces of this type were usually selected by the great Italian masters 
 as models for their representations of the Madonna, and it is worthy 
 of note that this is the type of face depicted by the great English por- 
 trait painters of the late eighteenth century as that of the famous 
 beauty, Emma, Lady Hamilton, All of the teeth in Class II, except 
 Form 1, have been designed for this form of face. The masculine 
 face of this type, with converging lines, often presents very strong 
 
 Tapering face — long. 
 Class II, Form 1. 
 
 Tapering face. 
 Class II, Form 
 
 Tapering face — long. 
 Class II, Form 3. 
 
 Illustration No. 29 
 
 Tapering face. 
 Class II, Form 4. 
 
 features. The lines of the cheek, from the malar bones to the lower 
 jaw, although couA'-erging considerably towards the chin, are very 
 straight and firm. For this type of face the teeth of Form 1, Class II, 
 have been made. There is no overlapping of the teeth in the strong- 
 est type of face of this class. 
 
 44 
 
"A ;N'ew Ci^ssification of Tooth Foems" 
 
 For tlie shorter tapering female faces in this class forms have 
 been designed, and also for the medium and longer tapering faces. 
 In all of these types, particularly those with the sharper form of face, 
 with a somewhat pointed arch, there is often more or less overlapping 
 of both centrals and laterals, but especially centrals. 
 
 On page 44 are two of the long tapering faces which are, I be- 
 lieve, much more frequently found in England and some parts of Italy 
 than in Germany or the United States, although many of the old iSTew 
 England stock had long faces. The teeth best suited to this type of 
 face will be rather long, with converging proximal lines such as are 
 seen in forms of Class XL We sometimes find in faces of this type, 
 in England, a rather short upper lip. In such cases, and, in fact, in 
 all cases where we find a short upper lip combined with prominence 
 of jaw, I think it better always to use short teeth or those of medium 
 length. 
 
 But teeth with tapering proximal sides should be selected for all 
 variations of the tapering face. The duplication and reversal of the 
 lines of the face in the shorter lines of the teeth produces an effect of 
 balance and harmony which a trained artist would perceive and under- 
 stand in a moment. If the face is long and only slightly tapering, 
 then the teeth of Form 1, Class I wiU give a good effect. In all taper- 
 ing faces with rather full cheeks the teeth in Class III are also per- 
 fectly suitable. Harmony is produced with these teeth, as with those 
 of Class II, by contrast or reversal of line. 
 
 <% 'fgf -^ 
 
 Illustration ]^o. 30 is the type of face to which I have given the 
 name "ovoid," and for which the teeth in Class III have been specially 
 made. The greatest width of the face, as I have already pointed out, is 
 in the region of the malar bones. But the entire lower part of the face 
 is heavier than in any other type. The cheeks are full, round, and thick. 
 Women with these facial characteristics are sometimes spoken of as 
 belonging to the voluptuous type. The beautifully curved outlines and 
 generally rounded character of the teeth in Class III will give the 
 most harmonious and satisfactory effects in faces of this t}^e. 
 
 45 
 
J. Leon Williams, D.D.S. 
 
 Slight depression of the laterals gives that proiniiieiice to the 
 canines which is in keeping with the strongest form of this face. With 
 the more delicate and refined type of face of this class there should be 
 overlapping of the laterals. The arch, as you see, is rounder than in 
 any other type. 
 
 Ovoid face. 
 Class III, Form 1 
 
 Ovoid face. 
 Class III, Form 2 
 
 Ovoid face. 
 Class III, Form 3 
 
 Illustration No. 30 
 
 Ovoid Face. 
 Class III, Form 4 
 
 I have shown you how the bolder forms of teeth in the present 
 system are adapted to the typal forms of faces. The general appli- 
 cation of the system to modifications of the typal faces can best be 
 
 46 
 
"A !N"ew Classification or Tooth Forms'^ 
 CLASS II MOULDS 
 
 (Illustrations show form but not sizes.) 
 
 Form 1. Class II. 
 A severe, nearly typal form. 
 
 Sizes from small to large from moulds IL, IM, IN, IP, IR. 
 
 Form 2. Class II. 
 Slightly modified by crossing with Class III. 
 
 Sizes from small to large from moulds 2L, 2M, 2N, 2P, 2IL 
 
 Form 3. Class II. 
 Slightly modified by crossing with Class I. 
 
 Sizes from small to large from moulds 3L, 3M, 3N, 3P, 3R. 
 
 Form 4. Class II. 
 Modified by Class III, a little more than Form 2. 
 
 Sizes from small to large from moulds 4L, 4M, 4N, 4P, 4R. 
 
 Illustration No. 31 
 
 47 
 
J. Leon Williams, D.D.S. 
 
 seen bj exhibiting the table of dassilication, (pages 49 to 61), in which 
 will appear the whole system in one view. 
 
 This table of classification presents three classes founded on the 
 three primitive types of natural teeth. Each class contains modifications 
 of the primary types corresponding with the variations in the types of 
 faces. The forms most closely resembling the primitive forms in 
 natural teeth, are most suitable for the strong, characteristic or typal 
 forms of faces. In nearly all faces which result from the crossing of 
 types we shall find one or other type dominant. Any given face will 
 approximate to the square, the oval, the tapering or the ovoid form. 
 We shall therefore determine the dominant factor and select our teeth 
 accordingly. Each section of the table represents a series of sizes 
 of one form of tooth. The teeth in any one section are called a 
 series, the only difference in all the teeth in a series being that of 
 size. They are all precisely the same form, but in sizes to match vari- 
 ations in size of faces of the same type. This is an entirely new fea- 
 ture in the manufacture of artificial teeth. How often we have had 
 the experience of fixing upon a certain shape of tooth, but which was 
 either too large or too small for our purpose, only to find that no other 
 size of that model was made. That, to my mind, has always been one 
 of the most incomprehensible inconsistencies of the old order of things. 
 Three or four sizes in each series will meet nine-tenths of the demands. 
 While on this subject of size of teeth perhaps I had better say that I 
 think the chief determining factor in adapting size of teeth to face 
 should be size of external mouth, opening and other features rather 
 than general size of face. Small teeth in a mouth with large opening, 
 no matter what the size of face may be, will always look hideous. 
 
 You are beginning to see now the comprehensiveness, the complete- 
 ness and the simplicity of this scheme of classification. In this series 
 of tables you have an arrangement that banishes all uncertainty and 
 guesswork. A patient comes to you for artificial teeth. You first de- 
 termine in what class the face belongs. If it is not a pure type you 
 decide on the dominant feature and determine that it is a modifica- 
 tion of the square, the oval, or the tapering face. You then select your 
 teeth on precisely the same principle. If it is a square face just pass- 
 
 ( Continued on page 62.) 
 
 48 
 
Classification Table 
 Trubyte Teeth 
 
 CLASS I 
 MODIFICATIONS OF THE SQUARE TYPE 
 
 FIVE FORMS IN GRADED SIZES 
 
 WHEN DIMENSIONS ARE NOT GIVEN THE SIZES ARE IN PREPARATION. 
 AI,!^ DIMENSIONS ARE IN MILUMETERS. 
 
 Similar dimensions in plain vulcanite pin teeth; combination sets with individual diatoric 
 posteriors, and combination sets with molar blocks. 
 
 FORM 1. The Long Modification of the Square Type. 
 
 Illustration represents form but not sizes. 
 
 Form 1. The long modification of the square form. 
 Sizes from small to large from moulds IC, ID, IE, IF, IH. 
 
 
 
 UPPERS 
 
 
 
 Mould 
 No. 
 
 I^ength 
 
 Central 
 
 Without Collar 
 
 Width 
 
 6 anteriors 
 
 Set up 
 
 Width 
 Full 14 
 Setup 
 
 Combined 
 
 Bite and Shut 
 
 of Central 
 
 Width of 
 Central 
 
 IC 
 ID 
 IE 
 IF 
 IH 
 
 9.75 
 10.25 
 10.75 
 11.50 
 
 42-43 
 45. 
 46-47 
 51. 
 
 103. 
 108. 
 109-110 
 123-124 
 
 8. 
 
 9. 
 
 9.5 
 
 9.5 
 
 7. 
 7.5 
 8. 
 8.5 
 
 LOWERS 
 
 Mould 
 No. 
 
 I,ength 
 
 Central 
 
 Without Collar 
 
 width 
 
 6 anteriors 
 
 Setup 
 
 width 
 Full 14 
 Set up 
 
 Combined 
 
 Bite and Shut 
 
 of Central 
 
 Width 
 
 Four 
 
 Incisors 
 
 IC 
 
 
 
 
 
 
 id 
 
 9. 
 
 32.5 
 
 102. 
 
 9. 
 
 21. 
 
 IE 
 
 9. 
 
 36. 
 
 104. 
 
 9. 
 
 22.5 
 
 IF 
 
 9.5 
 
 36. 
 
 106. 
 
 9. 
 
 23. 
 
 IH 
 
 10.25 
 
 40. 
 
 115. 
 
 9.5 
 
 25. 
 
 49 
 
J. Leon Williams, D.D.S. 
 
 CLASS I. 
 FORM 2 — Medium Long, Souare. 
 
 Illustration represents form but not sizes. 
 
 Form 2. The medium long modification of the square form. 
 Sizes from small to large from moulds 2C, 2D, 2E, 2F, 2H. 
 
 UPPERS 
 
 Mould 
 
 Length 
 
 Width 
 
 Width 
 
 Combined 
 
 width of 
 
 No 
 
 Central 
 
 6 anteriors 
 
 Full 14 
 
 Bite and Shut 
 
 Central 
 
 
 Without Collar 
 
 Set up 
 
 Setup 
 
 of Central 
 
 
 2 C 
 
 8.50 
 
 42-43 
 
 102-103 
 
 8. 
 
 7. 
 
 2 D 
 
 9.25 
 
 44 
 
 103 
 
 8.5 
 
 7.5 
 
 2 B 
 
 10. 
 
 46-47 
 
 108-109 
 
 9.25 
 
 8. 
 
 2 F 
 
 10.75 
 
 48-49 
 
 110-111 
 
 9.5 
 
 8.25 
 
 2 H 
 
 
 
 
 
 
 LOWERS 
 
 Mould 
 No. 
 
 Length 
 
 Width 
 
 Width 
 
 Combined 
 
 Width 
 
 Central 
 
 6 anteriors 
 
 Full 14 
 
 Bite and Shut 
 
 Four 
 
 Without Collar 
 
 Setup 
 
 Set up 
 
 of Central 
 
 Incisors 
 
 2 C 
 
 8.5 
 
 33. 
 
 100 
 
 7.5 
 
 20. 
 
 2 D 
 
 9. 
 
 34. 
 
 101 
 
 9. 
 
 21.5 
 
 2 n 
 
 9. 
 
 36.5 
 
 106 
 
 9. 
 
 23. 
 
 2 P 
 
 10. 
 
 37. 
 
 106 
 
 9.5 
 
 23.5 
 
 2 H 
 
 
 
 
 
 
 50 
 
"A N"ew Classification of Tooth Forms" 
 
 CI.ASS I. 
 FORM 3— Short Square. 
 
 Illustration represents form but not sizes. 
 
 Form 3. The short modification of the square form. 
 Sizes from small to large from moulds 3C, 3D, 3E, 3F, 311. 
 
 UPPERS 
 
 Mould 
 No. 
 
 I^ength 
 
 Central 
 
 Without Collar 
 
 Width 
 
 6 anteriors 
 
 Setup 
 
 Width 
 Full 14 
 Setup 
 
 Combined 
 
 Bite and Shut 
 
 of Central 
 
 width of 
 Central 
 
 3 C 
 3 D 
 
 3 K 
 
 8. 
 8.75 
 
 44-45 
 45-46 
 
 105-106 
 108-109 
 
 8. 
 
 8. 
 
 7.75 
 8. 
 
 LOWERS 
 
 Mould 
 No. 
 
 I^ength 
 
 Central 
 
 Without Collar 
 
 Width 
 
 6 anteriors 
 
 Setup 
 
 Width 
 Full 14 
 Setup 
 
 Combined 
 
 Bite and Shut 
 
 of Central 
 
 Width 
 
 Four 
 
 Incisors 
 
 3 C 
 3 D 
 3 E 
 
 7.75 
 8.75 
 
 35. 
 36. 
 
 103. 
 106. 
 
 8. 
 8.50 
 
 23. 
 
 23. 
 
 51 
 
J. Leon Williams, D.D.S. 
 
 CLASS I. 
 FORM 4 — The Feminine Modification of The Square Type. 
 
 Illustration represents form but not sizes. 
 
 Form 4. The feminine modification. 
 Sizes from small to large from moulds 4C, 4D, 4E, 4F. 
 
 UPPERS 
 
 Mould 
 No. 
 
 Length 
 
 Central 
 
 Without Collar 
 
 Width 
 
 6 anteriors 
 
 Setup 
 
 Width 
 Full 14 
 Setup 
 
 Combined 
 
 Bite and Shut 
 
 of Central 
 
 Width of 
 Central 
 
 4 C 
 4 D 
 4 E 
 4 F 
 
 9. 
 10.0 
 
 40. 
 45. 
 
 97. 
 
 107. 
 
 8. 
 9. 
 
 7. 
 8. 
 
 LOWERS 
 
 Mould 
 No. 
 
 Ivcngth 
 
 Central 
 
 Without Collar 
 
 Width 
 
 6 anteriors 
 
 Set up 
 
 Width 
 Full 14 
 Set up 
 
 Combined 
 
 Bite and Shut 
 
 of Central 
 
 Width 
 
 Four 
 
 Incisors 
 
 4 C 
 
 
 
 
 
 
 4 D 
 
 8. 
 
 29. 
 
 93. 
 
 8. 
 
 18. 
 
 4 E 
 
 
 
 
 
 
 4 F 
 
 9. 
 
 33. 
 
 102-103 
 
 8. 
 
 21. 
 
 52 
 
"A 'New Classification^ of Tooth Foems" 
 
 CLASS I. 
 FORM 5 — The Oval Modification of The Square Type. 
 
 Illustration represents form but not sizes. 
 
 Form 5. Oval modification. 
 Sizes from small to large from moulds 5C, SD, 5E, 5F, 5H. 
 
 UPPERS 
 
 
 I^ength 
 
 Width 
 
 Width 
 
 Combined 
 
 Width of 
 
 
 Central 
 
 6 anteriors 
 
 Full 14 
 
 Bite and Shut 
 
 
 
 Without Collar 
 
 Setup 
 
 Setup 
 
 of Central 
 
 
 5 C 
 
 
 
 
 
 
 5 D 
 
 
 
 
 
 
 5 E 
 
 
 
 
 
 
 5 F 
 
 
 
 
 
 
 5 H 
 
 11.5 
 
 50. 
 
 
 9. 
 
 8.50 
 
 LOWERS 
 
 Mould 
 No. 
 
 I,ength 
 
 Central 
 
 Without Collar 
 
 Width 
 
 6 anteriors 
 
 Setup 
 
 Width 
 Full 14 
 Setup 
 
 Combined 
 
 Bite and Shut 
 
 of Central 
 
 Width 
 
 Four 
 
 Incisors 
 
 5 C 
 5 D 
 5 E 
 5 F 
 5 H 
 
 10.5 
 
 38. 
 
 
 8.5 
 
 23.5 
 
 53 
 
J. Leok" Williams, D.D.S. 
 
 CI.ASS II. 
 MODIFICATIONS OF TAPERING TYPE 
 
 FOUR FORMS IN GRADED SIZES 
 
 FORM 1. — The Severe Modification of The Tapering Type. 
 
 Illustration represents form but not sizes. 
 
 Form 1. Class II. 
 A severe, nearly typal form. 
 
 Sizes from small to large from moulds IL, IM, IN, IP, IR. 
 
 UPPERS 
 
 Mould 
 No. 
 
 Length 
 
 Central 
 
 Without Collar 
 
 Width 
 
 6 anteriors 
 
 Setup 
 
 width 14 
 Setup 
 
 Combined 
 
 Bite and Shut 
 
 of Central 
 
 Width of 
 Central 
 
 1 L 
 1 M 
 1 N 
 1 P 
 1 R 
 
 10.5 
 11. 
 
 53. 
 
 55. 
 
 120. 
 122. 
 
 9.5 
 9.5 
 
 8.5 
 9. 
 
 LOWERS 
 
 Mould 
 
 No. 
 
 I<ength 
 
 Width 
 
 Width 14 
 
 Combined 
 
 Width 
 
 Central 
 
 6 anteriors 
 
 Setup 
 
 Bite and Shut 
 
 Four 
 
 Without Collar 
 
 Setup 
 
 of Central 
 
 Incisors 
 
 1 I. 
 
 
 
 
 
 
 1 M 
 
 
 
 
 
 
 1 N 
 
 10. 
 
 42. 
 
 112. 
 
 8.5 
 
 26. 
 
 1 P 
 
 10. 
 
 44. 
 
 114. 
 
 10. 
 
 27. 
 
 1 R 
 
 
 
 
 
 
 54 
 
"A 'Nbw Classificatiojst of Tooth Toems" 
 
 CLASS II. 
 FORM 2 — Second Modification of The Tapering Type. 
 
 Illustration represents form but not sizes. 
 
 Form 2. Class II. 
 Slightly modified by crossing with Class III. 
 
 Sizes from small to large from moulds 2L, 2M, 2N, 2P, 2R. 
 
 UPPERS 
 
 Mould 
 No. 
 
 I^ength 
 
 Central 
 
 Without Collar 
 
 Width 
 
 6 anteriors 
 set up 
 
 Width 14 
 Setup 
 
 Combined 
 
 Bite and Shut 
 
 of Central 
 
 Width of 
 Central 
 
 L 
 2 M 
 2 N 
 2 P 
 
 R 
 
 8.75 
 9.75 
 
 10.50 
 
 41. 
 
 44. 
 47-48 
 
 103. 
 106. 
 
 111. 
 
 8. 
 8. 
 9. 
 
 7. 
 
 7.5 
 
 8. 
 
 LOWERS 
 
 
 Length 
 
 Width 
 
 Width 14 
 
 Combined 
 
 Width 
 
 Mould 
 
 Central 
 
 6 anteriors 
 
 Setup 
 
 Bite and Shut 
 
 Four 
 
 No. 
 
 Without Collar 
 
 Setup 
 
 of Central 
 
 Incisors 
 
 1/ 
 2 M 
 
 8. 
 
 33. 
 
 99-100 
 
 8. 
 
 20. 
 
 2 N 
 
 9. 
 
 34. 
 
 102. 
 
 9. 
 
 21-22 
 
 2 P 
 
 10. 
 
 37. 
 
 108. 
 
 9.5 
 
 23-24 
 
 R 
 
 
 
 
 
 
 55 
 
J. Leon Williams, D.D.S. 
 
 CLASS IL 
 FORM 3 — The Third Modification of The Tapering Type. 
 
 Illustration represents form but not sizes. 
 
 Form 3. Class II. 
 Slightly modified by crossing with Class I. 
 
 Sizes from small to large from moulds 3L, 3M, 3N, 3P, 3R. 
 
 UPPERS 
 
 Mould 
 
 Length 
 Central 
 
 Width 
 
 6 anteriors 
 
 Width 14 
 
 Combined 
 Bite and Shut 
 
 Width of 
 
 No. 
 
 Without Collar 
 
 Setup 
 
 Set up 
 
 of Central 
 
 Central 
 
 Iv 
 
 
 
 
 
 
 M 
 
 
 
 
 
 
 3 N 
 
 9.75 
 
 45. 
 
 105. 
 
 8. 
 
 8. 
 
 3 P 
 
 10.50 
 
 50. 
 
 124. 
 
 8.5 
 
 8.5 
 
 R 
 
 
 
 
 
 
 LOWERS 
 
 Mould 
 No. 
 
 lycngth 
 
 Central 
 
 Without Collar 
 
 With 
 
 6 anteriors 
 
 Setup 
 
 Width 14 
 Setup 
 
 Combined 
 
 Bite and Shut 
 
 of Central 
 
 width 
 
 Four 
 
 Incisors 
 
 h 
 
 
 
 
 
 
 M 
 
 
 
 
 
 
 3 N 
 
 92 
 
 36. 
 
 103. 
 
 9. 
 
 22. 
 
 3 P 
 
 92 
 
 38. 
 
 114. 
 
 8. 
 
 25. 
 
 R 
 
 
 
 
 
 
 56 
 
^A ]S[ew CLAssiFiCATio:sr of Tooth Foems" 
 
 CI. ASS II. 
 
 Form 4. — The Fourth and Softest Modification of the 
 Tapering Type. 
 
 Illustration represents form but not sizes. 
 
 Form 4. Class II. 
 Modified by Class III, a little more than Form 2. 
 
 Sizes from small to large from moulds 4L, 4M, 4N, 4P, 4R. 
 
 UPPERS 
 
 Mould 
 No. 
 
 I^ength 
 
 Central 
 
 Without Collar 
 
 width 
 
 6 anteriors 
 
 Setup 
 
 Width 14 
 Setup 
 
 Combined 
 
 Bite and Shut 
 
 of Central 
 
 Width of 
 Central 
 
 4 Iv 
 
 4 M 
 
 8.75 
 
 41. 
 
 98-99 
 
 9. 
 
 8. 
 
 4 N 
 
 9.75 
 
 44-45 
 
 106. 
 
 
 
 4 P 
 
 
 
 
 
 
 4 R 
 
 
 
 
 
 
 LOWERS 
 
 Mould 
 No. 
 
 Length 
 
 Central 
 
 Without Collar 
 
 width 
 
 6 anteriors 
 
 Setup 
 
 Width 14 
 Setup 
 
 Combined 
 
 Bite and Shut 
 
 of Central 
 
 Width 
 
 Four 
 
 Incisors 
 
 41. 
 4 M 
 
 9. 
 
 31.5 
 
 95. 
 
 9.5 
 
 19.5 
 
 4 N 
 
 9. 
 
 35. 
 
 103. 
 
 9.5 
 
 22. 
 
 4 P 
 
 
 
 
 
 
 4 R 
 
 
 
 
 
 
 57 
 
J. Leon Williams, D.D.S. 
 
 CLASS III. 
 
 MODIFICATIONS OF THE OVOID TYPE 
 FOUR FORMS IN GRADED SIZES 
 
 FORM 1 — The Severe Modification of The Ovoid Type. 
 
 Illustration represents form but not sizes. 
 
 Form 1. Class III. 
 Sizes from small to large from moulds IT, lU, IW, IX, lY. 
 
 UPPERS 
 
 Mould 
 No. 
 
 I^ength 
 
 Central 
 
 Without Collar 
 
 Width 
 
 6 anteriors 
 
 Setup 
 
 Width 
 Full 14 
 Setup 
 
 Combined 
 
 Bite and Shut 
 
 of Central 
 
 Width of 
 Central 
 
 1 T 
 1 U 
 1 W 
 1 X 
 1 Y 
 
 
 
 
 
 
 LOWERS 
 
 
 Length 
 
 Width 
 
 Width 
 
 Combined 
 
 Width 
 
 Mould 
 
 Central 
 
 6 anteriors 
 
 Full 14 
 
 Bite and Shut 
 
 Four 
 
 No. 
 
 Without Collar 
 
 Setup 
 
 Setup 
 
 of Central 
 
 Incisors 
 
 1 T 
 
 
 
 
 
 
 1 U 
 
 
 
 
 
 
 1 W 
 
 
 
 
 
 
 1 X 
 
 
 
 
 
 
 1 Y 
 
 
 
 
 
 
 58 
 
"A ISTew Classification of Tooth Foems" 
 
 CIvASS III. 
 FORM 2 — The Second Modification op The Ovoid Type. 
 
 Illustration represents form but not sizes. 
 
 Form 2. Class HI. 
 Sizes from small to large from moulds 2T, 2U, 2W, 2X, 2Y. 
 
 UPPERS 
 
 Mould 
 No. 
 
 Length 
 
 Central 
 
 Without Collar 
 
 Width 
 
 6 anteriors 
 
 Setup 
 
 Width 14 
 Setup 
 
 Combined 
 
 Bite and Shut 
 
 of Central 
 
 Width of 
 Central 
 
 2 T 
 2 U 
 2 W 
 2 X 
 2 Y 
 
 
 
 
 
 
 LOWERS 
 
 Mould 
 No. 
 
 Length 
 
 Central 
 
 Without Collar 
 
 Width 
 
 6 anteriors 
 
 Setup 
 
 Width 14 
 Setup 
 
 Combined 
 
 Bite and Shut 
 
 of Central 
 
 Width 
 
 Four 
 
 Incisors 
 
 2 T 
 2 U 
 2 W 
 2 X 
 2 Y 
 
 
 
 
 
 
 59 
 
J. Leon Williams, D.D.S. 
 
 CLASS III. 
 FORM 3 — The Third Modification of The Ovoid Type. 
 
 Illustration represents form but not sizes. 
 
 Form 3. Class III. 
 Sizes from small to large from moulds 3T, 3U, 3W, 3X, 3Y. 
 
 UPPERS 
 
 Mould 
 No. 
 
 Length 
 
 Central 
 
 Without Collar 
 
 Width 
 
 6 anteriors 
 
 Setup 
 
 Width 14 
 Setup 
 
 Combined 
 
 Bite and Shut 
 
 of Central 
 
 Width of 
 Central 
 
 3 T 
 3 U 
 3 W 
 3 X 
 3 Y 
 
 
 
 
 
 
 LOWERS 
 
 Mould 
 No. 
 
 I^ength 
 
 Central 
 
 Without Collar 
 
 Width 
 
 6 anteriors 
 
 Setup 
 
 Width 14 
 Set up 
 
 Combined 
 
 Bite and Shut 
 
 of Central 
 
 Width 
 
 Four 
 
 Incisors 
 
 3 T 
 3 U 
 3 W 
 3 X 
 3 Y 
 
 
 
 
 
 
 60 
 
"A ISTew Classification of Tooth Foems" 
 
 CI.ASS III. 
 FORM 4 — The Softest Modification of The Ovoid Type. 
 
 Illustration represents form but not sizes. 
 
 Form 4. Class III. 
 Sizes from small to large from moulds 4T, 4U, 4W, 4X, 4Y. 
 
 UPPERS 
 
 Mould 
 No. 
 
 Length 
 
 Central 
 
 Without Collar 
 
 Width 
 
 6 anteriors 
 
 Setup 
 
 Width 14 
 Setup 
 
 Combined 
 
 Bite and Shut 
 
 of Central 
 
 Width of 
 Central 
 
 4 T 
 4 U 
 4 W 
 4 X 
 4 Y 
 
 
 
 
 
 
 LOWERS 
 
 Mould 
 No. 
 
 Length 
 
 Central 
 
 Without Collar 
 
 Width 
 
 6 anteriors 
 
 Setup 
 
 Width 14 
 Setup 
 
 Combined 
 
 Bite and Shut 
 
 of Central 
 
 Width 
 
 Four 
 
 Incisors 
 
 4 T 
 4 U 
 4 W 
 4 X 
 4 Y 
 
 
 
 
 
 
 61 
 
J. Leon Williams, D.D.S. 
 
 ing into the tapering form, you select a tooth with slightly converging 
 proximal lines and your harmony is perfect. Each set of teeth in a 
 series is numbered and the length and width of the centrals and com- 
 bined width of the six upper fronts is given on one line opposite the 
 number. You therefore have under your eye every condition for giv- 
 ing you exactly what you want. All the old wearisome, vexing search 
 among the miscellaneous collections of the trays is ended. You work 
 quickly, positively, accurately, artistically, as scientific men should. 
 
 -^ *% *% 
 
 All of the teeth in Class III are in an entirely new field, as models 
 of this beautiful type have never been made by any manufacturer be- 
 fore. And so far as my knowledge goes, only one model in Class II 
 has ever before been produced. By classifying and systematizing the 
 work I have therefore given you a far wider range of tooth-form than 
 you have ever had before, and with comparatively few forms. 
 
 And thus, you see, for the old vague, complex and bewildering 
 effort at instruction in the adaptation of teeth to certain hypothetical 
 temperamental conditions, which nobody ever understood because they 
 never existed, we substitute a few simple, clear, positive rules, based 
 on a fundamental esthetic principle. And the essence of that principle 
 is the direct adaptation of tooth form to facial contour. A square tooth 
 for a square face ; an oval tooth for an oval face ; an ovoid tooth for an 
 ovoid face, and teeth with proximal lines converging toward the neck 
 for the tapering faces with lines converging toward the chin. 
 
 While the improvements in the outline forms and proportions of 
 which I have been speaking are fundamental improvements in the new 
 forms of teeth, because they strike at the very foundation of good 
 prosthesis, it has been possible to incorporate into the anteriors of the 
 new teeth other improvements, some of which have long been asked 
 for by the dental profession. I shall refer to these under the head- 
 ings of: — 
 
 IMPEOVED LABIAL SUEFACES AKD IMPEOVED COLOEINGS. 
 
 Many a dentist who has had difficulty in making a satisfactory 
 restoration of a lost natural tooth, even when the artificial tooth has 
 
 62 
 
"A I^Tew Classificatiost of Tooth Fokms" 
 
 seemed of the riglit size, form and color, has been at a loss to account 
 for the difficulty, and has attributed it to the difference in appearance 
 between the natural tooth and the porcelain. 
 
 The fact has been that the porcelain tooth reflected the light in 
 a different way than the natural tooth did, because the natural tooth 
 presented a slightly roughened labial surface which diffused the light, 
 while the porcelain tooth presented a smooth surface which did not 
 diffuse it. (It should be noted here that some natural teeth have smooth 
 labial surfaces, but they seem to be in the minority, and are not as 
 pleasing in color as those with rougher surfaces.) 
 
 -^ -^ *% 
 
 I£ the labial surface of an upper central which is beautiful in color 
 and softness be carefully examined, it will be seen to present very deli- 
 cate longitudinal striations due to the succession of calcification of the 
 ameloblasts or enamel cells. These striations have a very constant pat- 
 tern which is horizontally across the labial surface of the tooth, by a 
 series of compound curves. The striations undergo regular changes in 
 form and size in different parts of the tooth. 
 
 These striations work very important color effects in the appear- 
 ance of the teeth. They soften the high lights which would other- 
 wise be reflected with much brilliancy from certain parts of the tooth, 
 and which would often make the teeth a point of too strong light to 
 harmonize well with the rest of the face. They soften the shadows, 
 which would otherwise be too deep. They do this by breaking up the 
 waves of reflected light so that they are not returned to the eye in 
 that rhythmical succession given by polished surfaces. The result is 
 that the whole surface of the tooth is rendered considerably softer 
 than it would otherwise be. 
 
 JSTot only is this surface of the tooth rendered softer, but careful 
 experiments with optical instruments seem to show that the whole 
 outline of the tooth is given a softer appearance by this diffusion of 
 light. 
 
 63 
 
J. Leon Williams, D.D.S. 
 
 The methods iu use for the commercial production of porcelain 
 teeth have not permitted the reproduction of labial surfaces which could 
 diffuse the reflected light in the manner just referred to. We have had 
 strong developmental grooves and occasional cross grooves, possibly 
 intended to represent deficient calcification. Otherwise the labial sur- 
 faces have been smooth. 
 
 The result of the smoothness of porcelain labial surfaces has been 
 that the light from them has not been diffused and softened. The high 
 lights have been strong and the shadows deep. The outlines have been 
 always clearly defined. And when placed beside natural teeth of even 
 like form and color, they have presented, to the observing eyes, differ- 
 ences which have often made them unsatisfactory. The general com- 
 ment was that the teeth looked "too glassy." 
 
 '^ '^ '^ 
 
 This matter of diffusing the reflected lights and giving Trubyte 
 teeth more natural appearances has received the most exacting atten- 
 tion, with the result that the labial surfaces of Trubyte teeth present 
 enamel markings which are anatomically correct in form and which 
 soften the reflected high lights and shadows in the same way the natu- 
 ral teeth do. 
 
 This softening of the lights and shadows changes the whole appear- 
 ance of the teeth, so that they seem to be of a different porcelain or 
 texture from similar teeth not so softened. 
 
 This improvement, which I have passed over in few words, is of 
 the very greatest value to the prosthetic worker who wishes to render 
 his patient a high type of service and receive a proper fee therefor. 
 When these moulds are produced in facings and crowns, the full force 
 of the improvement will be apparent to all. 
 
 The incorporation of these enamel markings, in correct form, has 
 been a task of great difficulty. It has been necessary to perfect a new 
 and improved method of mould making, and this has demanded almost 
 two years of constant labor. 
 
 COLOE liJf AETIFICIAL TEETH. 
 
 If the knowledge of form in natural and artificial teeth has been 
 in a chaotic condition there has hardly been sufficient scientific knowl- 
 
 64 
 
"A E"e-w Classification of Tooth Foems" 
 
 edge of color in teeth to justify the use of the word "chaotic" or any 
 other adjective concerning it. We have known practically nothing and 
 certainly nothing practical about the right use of color in porcelain 
 teeth. 
 
 As time went on and I became more and more absorbed in the 
 study and investigation of tooth form and in the practical working out 
 of the results of my investigation in carving models for the Trubyte 
 System, it became apparent that some one else would have to take up 
 this matter of analyzing the color of different types of natural teeth 
 and adapting the results obtained in this branch of our work to the 
 new system of artificial teeth. 
 
 Dr. Clapp kindly offered to take this work off my hands, and he 
 entered upon this very difficult task with the earnestness and deter- 
 mination that he puts into everything that he undertakes. 
 
 This work, under his direction, has now been in progress for 
 nearly two years, and the first results are being embodied in the 
 Trubyte system of teeth. 
 
 «^ -^ *<fe 
 
 Many progressive dentists here in America and others in Europe 
 had, for years, been calling attention to the unnatural coloration of 
 artificial teeth, but no one had ever suggested any standard of color 
 and no one had ever determined what the actual colors are in human 
 teeth. This, then, was the arduous task Dr. Clapp took upon himself. 
 He had first to determine the actual primary and secondary colors in 
 natural teeth, and he had then to discover or invent a method of stand- 
 ardizing the results of this investigation so as to secure a practical 
 application of the knowledge gained to the coloration of artificial teeth. 
 
 He was fortunate at the outset in being able to secure the services 
 of one of the world's greatest commercial color experts. With his aid, 
 the colors in a large number of sets of natural teeth were carefully 
 analyzed and recorded in exact terms. The secondary and tertiary col- 
 ors were worked out, and the whole thing reduced to charts, and finally 
 to paintings representing the exact depth of color in different teeth and 
 the distribution of that color. 
 
 65 
 
J. Leon Williams, D.D.S. 
 
 COLOR ANALYSIS 
 
 u 
 
 u 
 
 Miss D. A. 
 
 UPPERS 
 
 , R. Central , 
 
 ' ' Lateral 
 
 ' ' Cuspid 
 
 " 1st bicuspid 
 
 " 2nd " 
 
 ' ' 1st molar 
 
 L. Central 
 
 * ' Lateral 
 
 ' ' Cuspid 
 
 ' * 1st bicuspid 
 
 " 2nd " 
 
 " 1st molar. . . 
 
 LOWERS 
 L. R. Central 
 
 ' ' Lateral 
 
 ' ' Cuspid 
 
 " 1st bicuspid.. 
 L. L. Central 
 
 " Lateral 
 
 " Cuspid 
 
 " 1st bicuspid.. 
 
 Age 19 
 
 Ht. 5.6" 
 
 Wt. 119 lbs. 
 
 Eyes 
 Hair 
 Skin 
 
 f Cervical 
 I Incisal 
 f Cervical 
 \ Incisal 
 j Cervical 
 \ Incisal 
 / Cervical 
 1 Incisal 
 J Cervical 
 \ Incisal 
 / Cervical 
 \ Incisal 
 ( Cervical 
 ( Incisal 
 I Cervical 
 t Incisal 
 f Cervical 
 \ Incisal 
 f Cervical \ 
 \ Incisal J 
 { Cervical \ 
 / Incisal J 
 { Cervical I 
 ( Incisal \ 
 
 / Cervical 
 \ Incisal 
 f Cervical 
 \ Incisal 
 f Cervical 
 \ Incisal 
 { Cer\acal 1 
 } Incisal j 
 i Cervical 
 I Incisal 
 / Cervical 
 \ Incisal 
 f Cervical 
 \ Incisal 
 f Cervncal \ 
 \ Incisal J 
 
 Red 
 
 17.5 
 Dead 
 4.1 
 
 43.0 
 Blac 
 3.0 
 
 1.1 
 
 1.1 
 
 1.85 
 
 1.85 
 
 1.85 
 
 1.9 
 
 2.0 
 
 2.0 
 
 2.0 
 2.4 
 
 1.1 
 
 1.1 
 
 1.85 
 
 1.85 
 
 1.95 
 
 2.0 
 
 2.0 
 2.0 
 2.4 
 
 1.0 
 1.0 
 
 2.4 
 2.3 
 2.6 
 2.3 
 
 2.0 
 
 Yellow 
 
 16.0 
 k 
 .88 
 
 1.4 
 
 1.35 
 
 2.9 
 
 2.7 
 
 3.3 
 
 3.1 
 
 2.7 
 
 2.6 
 
 2.3 
 
 3.7 
 
 1.5 
 1.4 
 2.9 
 
 2.5 
 3.2 
 3.1 
 
 2.7 
 2.3 
 3.6 
 
 2.5 
 2.4 
 3.4 
 2.9 
 3.3 
 2.7 
 
 2.5 
 
 1.0 
 
 2.5 
 
 1.25 
 
 2 4 
 
 2.4 
 
 3.4 
 
 2.3 
 
 2.9 
 
 2.4 
 
 3.1 
 
 2.2 
 
 2.6 
 
 2.0 
 
 2.5 
 
 .20 
 .34 
 
 1.3 
 
 1.7 
 
 1.75 
 
 1.85 
 
 1.6 
 
 1.7 
 
 1.6 
 
 2.3 
 
 .20 
 .38 
 1.3 
 1.6 
 1.75 
 1.8 
 
 1.6 
 1.6 
 
 2.3 
 
 .74 
 .76 
 
 1.6 
 
 1.8 
 
 1.5 
 
 1.55 
 
 1.5 
 
 .74 
 .95 
 
 1.6 
 
 1.8 
 
 1.45 
 
 1.5 
 
 1.5 
 
 Color Developed 
 
 Black Orange 
 
 6.0 
 
 1.5 
 
 .88 
 
 2.12 
 
 .20 
 
 .90 
 
 .34 
 
 .76 
 
 1.3 
 
 .55 
 
 1.7 
 
 .15 
 
 1.75 
 
 .10 
 
 1.85 
 
 .05 
 
 1.6 
 
 .40 
 
 1.7 
 
 .30 
 
 1.6 
 
 .40 
 
 2.3 
 
 .10 
 
 .20 
 
 .90 
 
 .38 
 
 .72 
 
 1.3 
 
 .55 
 
 1.6 
 
 .25 
 
 1.75 
 
 .20 
 
 1.8 
 
 .20 
 
 1.6 
 
 .40 
 
 1.6 
 
 .40 
 
 2.3 
 
 .10 
 
 .74 
 
 .26 
 
 .76 
 
 .24 
 
 1.6 
 
 .80 
 
 1.8 
 
 .50 
 
 1.5 
 
 1.1 
 
 1.55 
 
 .75 
 
 1.5 
 
 .50 
 
 .74 
 
 .26 
 
 .95 
 
 .30 
 
 1.6 
 
 .80 
 
 1.8 
 
 .50 
 
 1.45 
 
 .95 
 
 1.5 
 
 .70 
 
 1.5 
 
 .50 
 
 25.5 yel. 
 1.1 red 
 
 .3 yel. 
 
 .25 " 
 
 1.05 " 
 
 .85 " 
 
 1.45 •' 
 
 1.2 " 
 .7 " 
 .6 " 
 
 .3 " 
 
 1.3 " 
 
 .4 " 
 
 .3 " 
 
 1.05 " 
 
 .65 " 
 
 1.25 " 
 
 1.1 " 
 
 .3 
 1.2 
 
 1.5 
 
 1.15 
 
 1.0 
 
 .6 
 
 .7 
 
 .4 
 
 66 
 
"A JSTew Classification- of Tooth Foems" 
 
 Depths of colors in the necks of the upper 
 anteriors. 
 
 Depths of colors in the incisal halves of 
 the upper anteriors. 
 
 DIAGRAMMATIC REPRESENTATION OF THE DEPTHS OF COLOR 
 TABULATED ON PAGE 66. 
 
 The different depths of color in different parts of a tooth and in different teeth 
 can be diagrammatically shown in charts like those here reproduced. 
 
 The horizontal base line of the charts represents in color. Each of the 
 parallel horizontal chart lines represents a depth of 1-10 of a unit, upward from 0. 
 The line locating the gray in the teeth is drawn solid. That representing the orange 
 is drawn in dashes and that representing the yellow, in dots. This set of teeth showed 
 no other colors. This person's hair is dead black, the eyes are brown, and the 
 skin showed a good deal of red. 
 
 The charts show that the necks of the upper centrals and laterals in this set 
 exhibit less gray than the cutting edges, but more orange and yellow. The cuspids 
 exhibit practically the same amount of gray and orange throughout the teeth, but 
 the necks show more yellow than the cutting edges. This free yellow gives these 
 cuspids their character. 
 
 The necks of one lower central and both lower laterals in this set, exhibit less 
 gray than the cutting edges, but the necks of the lower laterals exhibit more orange 
 and yellow. The lower cuspids exhibit practically an even depth of gray through- 
 out, but much more orange and yellow in the necks. There is a good deal more 
 orange in the lower cuspids than in the upper cuspids. 
 
 Depths of colors in the necks of the lower Depths of colors in the incisal halves of 
 
 anteriors. the lower anteriors. 
 
 Illustration No. 32 
 
 67 
 
J. Leon Williams, D.D.S. 
 
 Some of the difficulty of that work may be understood when I tell 
 you that it has taken two years to gain the necessary information, and 
 that in addition to our own efforts from one to three experts have been 
 working steadily. They state that they never saw such difficult and 
 delicate work, nor such exacting taskmasters as we have proven. How 
 ever, we have gotten at least the greater part of what we want and 
 have incorporated it into Trubyte Teeth. 
 
 Let me set before you some facts regarding the distribution of 
 colors in different anterior teeth. Let us take as a shade in which to 
 work, Twentieth Century shade 7. The color in the upper central will 
 be found distributed about as it is in the shade tooth, because the 
 manufacturers seem to have paid pretty close attention to the shading 
 in the upper centrals, and to have imitated it pretty well. Their error 
 consists in the fact that they have applied this form of shading to all 
 the anterior teeth. 
 
 The shading of the upper laterals is very much like that of the 
 upper centrals in depth, but the incisal third of the lateral is darker. 
 This does not seem quite logical in view of the fact that the incisal 
 half of this tooth is largely composed of the enamel plates, with only 
 a small amount of dentine. But I have the analyses, the charts and 
 the color drawings before me as I write, and they indicate that the 
 incisal half of the upper lateral has more color than the same portion 
 of the upper central. It is especially distinguished by the presence 
 of more gray. 
 
 -^ -^ -^ 
 
 The cervical half of the upper cuspid shows more color than the 
 cervical half of the upper central or lateral, while the cuspid shows the 
 widest variation in individual teeth, and that without any apparent 
 relation to the color in the incisal halves of the central and lateral. 
 It has, of course, always been known in a general way, from observa- 
 tion, that the cuspids were darker than the centrals, but there has 
 never been any exact knowledge about the conditions of this variation. 
 
 The depth of color in the lower anteriors, as compared with the 
 depths of color in the upper anteriors, differs markedly in different indi- 
 viduals and apparently in different races. I think a fair statement of 
 it would be that the colors seen in the upper teeth are slightly deeper 
 in the lower anteriors. The cutting edges are also generally deeper in 
 color. This makes the color throughout each tooth in the lower an- 
 teriors more uniform. The effect of the deeper average of color and 
 of the uniformity affords a pleasing contrast with the upper teeth. 
 
 68 
 
VARIATIONS OF COLOR IN NATURAL TEETH 
 
 GRAY 
 
 ORANGE 
 
 GREEN 
 
 VIOLET 
 
 Illustration No. 
 
VARIATIONS OF COLOR IN NATURAL TEETH— Continued 
 
 YELLOW 
 
 BLUE 
 
 RED 
 
 Illustration Xo. 34 
 
"A ^Ew CLAS.siFiCATio:sr OF Tooth Forms" 
 
 These color effects have been achieved in Trubyte teeth by placing 
 the dentine and enamel bodies in such way as to reproduce the natural 
 variations. This has been made possible by the translucency of the 
 porcelain from which these teeth are made. 
 
 These colors can be properly placed only by people especially 
 trained and by allowing them much more time than is required for 
 shading the ordinary porcelain teeth of commerce. This necessarily 
 increases the cost of the teeth, but this increase in cost is trifling when 
 the advantages gained are considered. 
 
 The results attained in coloring Trubyte teeth are superior to 
 those w^hich will ordinarily be accomplished by staining and burning 
 teeth by the individual dentist. The colors are in the teeth, are the 
 result of proper placing of the dentine and enamel bodies, and are 
 under the glaze. The results are an enormous stride in advance of 
 what has been heretofore commercially offered. 
 
 One who has not closely studied the colors in natural teeth can 
 hardly realize how delicate and beautiful is the color scheme by which 
 nature adorns a really fine set of teeth. The primary colors, red, blue 
 and yellow are, as one who has made a scientific study of color would 
 expect, found in every human tooth. The blending of these primary 
 colors produces the secondary colors — the orange, green and violet. It 
 is very interesting to note the parallelism of form and color in teeth 
 as elsewhere in nature. 
 
 As one or other of the three primary types of form is usually 
 dominant in every upper central incisor, and to a certain degree in 
 every human tooth, so one or other of the three primary colors is 
 generally dominant and a color expert might classify most human teeth 
 as pink, blue or yellow. 
 
 '^ '^ '^ 
 
 As much the larger proportion of teeth are, in form, the result of 
 the crossing or blending of the primary forms, so also in color the 
 blending or mixing of the primary colors produce a great variety of 
 secondary or intermediate colors in which orange, green and violet 
 are clearly seen. 
 
 It is a rare thing to find two teeth in any given mouth of exactly 
 the same color. Just as it is rare to find a pair of teeth on different 
 sides of the mouth of the same shape. It is these slight variations in 
 form and color which give great beauty, harmony and naturalness to 
 a fine set of natural teeth, and it is mechanical regularity in form and 
 sameness in coloring which make artificial teeth, as they have hereto- 
 fore been made, so false looking, so unnatural and repulsive. 
 
 69 
 
J. Leon Williams, D.D.S. 
 
 As a more detailed account of the results of our investigation 
 into the color of natural teeth will shortly be published in book form * 
 and offered to the profession, I shall give here but a brief resume of 
 this work. The table on page 66 gives a color analysis, according to 
 the scientific method we have followed, of a single set of natural teeth, 
 and on the following page will be seen a diagrammatic representation 
 of the depths of color in the incisors according to the table. 
 
 The first three columns in the table show the percentages of the 
 standard colors used to determine or develop the actual colors in the 
 tooth which are indicated in the three columns on the right. 
 
 When I tell you that for every figure set down in those columns 
 a considerable number of trials with optical apparatus of the most 
 exacting nature had to be made before the final result was reached, 
 you will, I think, begin to understand why this work could not be 
 completed quite as rapidly as some of our impatient confreres thought, 
 and also why a slight advance in the cost of these teeth has been neces- 
 sary. Trubyte teeth, as I have said, are "shaded" on the basis of this 
 investigation into the color of natural teeth. The upper central is 
 always of the shade on the guide. This is the dominant color of the 
 set the shading of which is accomplished by varying the depth of this 
 color. The color in the upper laterals is more evenly distributed 
 throughout the tooth just as we find it in nature. 
 
 The upper cuspids are more deeply shaded in both cervical and 
 incisal halves than either the centrals or the laterals. The color in the 
 bicuspids and molars is slightly deeper. 
 
 The color in the incisal halves of the lower anteriors is slightly 
 deeper than in the incisal halves of the uppers. 
 
 *% '^ •% 
 
 For the first time in the commercial history of porcelain teeth they 
 are now supplied to the dentist of a color closely approximating that 
 found in natural teeth. The color, being based on nature, gives a far 
 finer effect than the arbitrary method of hand staining or the still more 
 imperfect method of selecting a variety of colors from different sets and 
 assembling them into one. 
 
 Dentures made with teeth shaded in this natural way are, artis- 
 tically, so superior to those made of one shade that a comparison can- 
 not well be made. 
 
 In form, in surface texture and in color the Trubyte System of 
 teeth has reached such a high standard of achievement that I hope 
 and believe the finest artistic and mechanical ability in our profession 
 
 * Prosthetic Articulation. 
 
 TO 
 
Illustration No. 35 
 
 Five Stages of Wear of Natural Teeth: A. Unworn Stage. B. Greatest Efficiency Stage. 
 C. Reduced Efficiency Stage. D. Much Worn Stage. E. Stage of Extreme Wear. Trubyte 
 teeth exhibit the stage of wear shown in Figure A and the depth of bite shown in Figure B. 
 
 Illustration No. 36 
 
 Figure A shows occlusal surfaces of upper and lower molars ground to articulating form after 
 method formulated by Dr. Bonwill. 
 
 Figure B shows same molars occluded. 
 
 Figure C shows longitudinal section of same teeth. 
 
 Figure D shows the same occlusal surfaces of the anatomical moulds of the Dentists Supply 
 Company. These are carved to much more nearly correct anatomical form than were the teeth 
 of Dr. Bonwill's time. 
 
 Figure E shows molars occluded. The longitudinal groove is entirely different in charactei 
 from that shown in Figure B. The upper buccal cusp does not overhang the lower molar as in 
 Figure B. The depth of bite in these teeth is only half as great as in those shown in Figure B. 
 
 Figure F shows a longitudinal section of the same teeth. 
 
 Figure G shows the occlusal surfaces of Trubyte teeth, with the formation for cracking, 
 tearing and cutting. 
 
 Figure H shows Trubyte first molars occluded. ■ n j 
 
 Figure I shows a longitudinal section of these teeth. Instead of presenting the flat opposed 
 surfaces shown in Figure C or the single convex surfaces shown in Figure F, these teeth exhibit 
 from two to five grooves and from three to six cusps each. 
 
"A l^Ew Classification of Tooth Foems" 
 
 ■will be aroused by their appearance and stimulated to tbe production 
 of such results as have never before been known in the history of 
 dentistry. 
 
 TEUBYTE BICirSPIDS AND MOLAES. 
 
 And now I come to a part of the paper which describes mechanical 
 advances of such importance to the dentist and to the patient as a 
 masticating animal, that, from this point of view also, it will hardly 
 be possible to exaggerate the advantages of the new teeth. I refer to 
 the greatly improved forms of the masticating surfaces of the bicuspids 
 and molars perfected by my associate, Professor Dr. Gysi. 
 
 Professor Gysi has established the fact that proper forms of porce- 
 lain bicuspids and molars cannot be produced by copying natural 
 teeth, because at no time do the natural teeth present all the charac- 
 teristics essential to artificial teeth. 
 
 It is logical that this should be so. The natural teeth are fixed in 
 the jaw. In adult life they are capable of a masticating force of from 
 100 to 300 pounds, with perhaps an average of 150 pounds. In early 
 life they exhibit deep bites and great efficiency. In later life they ex- 
 hibit relatively flat bites and require the exercise of great force to 
 make them efficient. 
 
 Artificial teeth on dentures are not firmly fixed in the mouth and 
 on bridges are less firmly fixed than when each tooth has its own 
 healthy root. Dentures are believed to be capable of exerting a pres- 
 sure not greatly in excess of 15 pounds, perhaps 20 or 25 pounds as a 
 maximum, as compared with the 150 pounds of the natural teeth. 
 Bridge teeth are capable of exerting less power than individual, 
 healthy natural teeth. 
 
 •^ % '^ 
 
 Artificial teeth, then, with one-tenth the power of the natural teeth, 
 must discharge the same functions as the natural teeth, or the food 
 cannot be properly prepared for digestion. They must exhibit shallow 
 bites in order that the dentures or the bridge may not be subjected to 
 severe lateral strains. Teeth which will function efficiently and be 
 stable under such conditions cannot be formed by copying natural 
 teeth, which were designed to function under very different conditions. 
 They can be made only by applying engineering principles to the 
 designing of surfaces which shall function under actual conditions, 
 just as the engineer designs his bridge for the load it must carry. 
 
 In the brief space of time left me, I shall draw your attention to 
 the application of these engineering principles only for the accomplish- 
 ment of some of the greater objects sought in Trubyte bicuspids and 
 molars. The points are: 
 
 71 
 
J. Leon Williams, D.D.S. 
 
 Proper opening and closing articulation in bicuspids. 
 
 Proper sliding articulation in the molars. 
 
 High cusps, deep fosssc and sulci with shallow bites. 
 
 A large number of properly interacting facets on the occlusal 
 surfaces of the molars. 
 
 Precisely as 1 have followed the general natural form in design- 
 ing the Trubyte System so Dr. Gysi has based the forms of his masti- 
 cating surfaces on nature, but he has greatly improved on l^ature in 
 eflficiency of mastication as I have improved on form. 
 
 «<fe -% *<& 
 
 PEOPEE OPENING AND CLOSING ARTICULATION IN BICUSPIDS. 
 
 Artificial bicuspids have heretofore been merely little molars. 
 They have exhibited the same form of sliding articulation as the 
 molars. This is anatomically incorrect and deprives the patient of 
 the benefits to be derived from the very important functions of the 
 bicuspids. Their functions are to catch, hold, and crack brittle foods, 
 and to pierce between fibers which have been placed along them and 
 are being held by the sliding articulation of cuspids and molars. 
 
 Bicuspids can discharge these important functions only by exhib- 
 iting an opening and closing articulation while the cuspids and molars 
 are in sliding articulation. Trubyte bicuspids exhibit this most impor- 
 tant form of Articulation. 
 
 PEOPEE SLIDING ARTICULATION IN THE MOLAES. 
 
 The articulation desired in the molars is entirely different from 
 that in the bicuspids. When the teeth in the lower jaw come up 
 against those in the upper, with food between them, the buccal and 
 lingual cusps should interdigitate to prevent the escape of solid food, 
 and as the jaw returns to the position of central occlusion, the opposing 
 upper and lower cusps should maintain a certain form of sliding 
 articulation. This form of articulation is very different in character 
 from that heretofore possible to porcelain molars. 
 
 Porcelain molars which have heretofore been offered have articu- 
 lated by the sliding of one cusp past another. This is effective to a 
 certain degree, but not sufficiently so to render porcelain teeth efficient 
 under the small pressure which they can exert. It is necessary to the 
 maximum of efficiency that each of these cusps should cut across the 
 opposing cusp in much the same way a barber draws a razor across a 
 strap, or like the action of the figures shown in Illustration l^o. 38. 
 
 This action greatly increases the cutting efficiency of the teeth by 
 causing each ridge to cut throughout its length, instead of for a short 
 distance only. 
 
 72 
 
T" 
 
 o 
 
 The bone cracking teeth of the dog. 
 
 Similar cracking action by human bicuspids. 
 
 > r » ^ 
 
 Buccal cusps interdigitate in articulation. 
 
 Diagrammatic representation of a grain trap. 
 Same trap in Trubyte bicuspids. 
 
 Lingual cusps open to receive seeds and 
 grains. 
 
 Diagram of tearing action. 
 Illustration No. 27 
 
"A jSTew Classificatioit of Tooth Foems" 
 
 The formation of cusps for such interaction is possible only by 
 the application of engineering principles. I have seen the formulae 
 and the methods by which Professor Gysi has arrived at these results, 
 and they are as complicated as the desigTiing of a cantilever bridge. 
 The action of each part of each tooth has been known before an instru- 
 ment was taken in hand for the carving. It is the highest form of 
 praise to say that the resulting teeth are as near to the theoretical 
 results as anything in porcelain can be. They set up easily and func- 
 tion efficiently. 
 
 It must not be thought that because I have quoted Professor Grysi 
 as to the application of engineering principles to the formation of 
 these surfaces, nature's laws have been departed from, and unnatural 
 forms produced. Such is not the case. Nature is the most consum- 
 mate engineer of us all. She adapts her forms to function with the 
 exercise of the smallest possible force, and with the least disturbance 
 of parts. 
 
 •^ -^ '^ 
 
 The laws which she employed for the formation of the permanent 
 teeth and which made them efficient with the relatively small masticat- 
 ing force of the child have been employed. The depth of bite has 
 been reduced so that it is much more shallow than in efficient human 
 teeth, and only half as deep as in the present anatomical moulds. 
 
 The ridges have been arranged to present the longest cutting 
 action possible and to bring into action a large number of small sur- 
 faces, interacting properly, in order that the food may be more thor- 
 oughly masticated. The forms of these ridges have been carefully 
 designed by applying the laws exhibited in human teeth at the period 
 of their greatest masticating efficiency. 
 
 I have been asked whether teeth so accurately formed can be set 
 up by the average dentist. In reply let me say that they can be better 
 set than any other and less accurate forms. They cannot always or 
 perhaps often be articulated for individual peculiarities of jaw move- 
 ment without some small amount of grinding, but this grinding can 
 be done with the carborundum and glycerine, and will be neither 
 tedious nor difficult. Little or no grinding with a stone should be 
 necessary. 
 
 IMPROVED FORMATIONS IN CUSPID EDGES. 
 
 Both Dr. Gysi and myself have contended from the first that the 
 highest success in the making of artificial teeth cannot be reached by 
 baldly copying natural teeth. 
 
 73 
 
J. Leon Williams, D.D.S. 
 
 Dr. Gysi makes the same claim from the point of view of efficiency 
 in mastication. He has originated a phrase that will become classic in 
 prosthetic dentistry which is that "the problem of restoring mastica- 
 tion is an engineering problem." 
 
 The cutting edges of the cuspids present the most anterior example 
 of the application of engineering principles. For these edges must be 
 quite differently formed in porcelain teeth than they are in newly 
 erupted natural teeth. 
 
 IsTatural upper cuspids are often very beautiful in form, and before 
 wear has mutilated them, present long and often pleasing cusps. These 
 are the forms which have generally been reproduced in porcelain teeth. 
 They are the forms which have made it practically impossible to 
 arrange the upper and lower cuspids properly, without extensive grind- 
 ing of the edges. Many find this grinding difficult of accomplishment. 
 
 The edges of the upper and lower cuspids here shown have been 
 shaped to function properly. The anterior facet on the edge of the 
 lower cuspid is always short, so that it may occlude with the distal 
 facet on the cutting edge of the upper lateral. The mesial facet of the 
 upper cuspid is usually long, in normal dentures after wear, in order 
 that this tooth may both occlude and articulate with the lower cuspid, 
 and that the point of the upper cuspid may pass through the inter- 
 dental space posterior to the lower cuspid and not climb on the lower. 
 This is one of the most important relations in the articulation of den- 
 tures, and has heretofore been one of the most difficult to attain. The 
 fact that it may easily be attained with Trubyte teeth will greatly 
 facilitate the arrangement of these teeth and their efficiency in mastica- 
 tion. 
 
 '^ '^ '^ 
 
 SUMMARY. 
 
 A brief summary of the facts and principles involved in this 
 system of artificial teeth: 
 
 1st. This system is based on the new classification of the natural 
 teeth which I have discovered, the essential feature of which is the 
 three primary or primitive forms of the upper central incisors common 
 to all races of men and the anthropoid apes. 
 
 2d. By the crossing or combining of these primary forms every 
 conceivable form of human tooth can be produced. 
 
 3d. By applying a knowledge of design to the three primary 
 forms of natural teeth a system of teeth has been produced in which 
 all the lines and contours of any given set are in more perfect har- 
 mony and balance than we usually find in Nature. 
 
 74 
 
Food cells are isolated and the cell walls 
 broken by the rubbing together of the facets. 
 The rubbing action is diagrammatically shown 
 by the mortar and pestle in which substances 
 are pulverized. 
 
 Diagrammatic illustration of the cutting ac- 
 tion exhibited by opposed ridges and facets in 
 Trubyte molars. If the point A of the upper 
 block be carried to the point C of the lower 
 block, and then the upper block be so moved 
 as to bring the point B directly over the 
 point D ot the lower block, each of the 
 opposed ridges will cut throughout its length 
 with a drawing motion. This is the longest 
 and most efficient "cut" possible to these 
 ridges. 
 
 _ks^-^^ 
 
 Diagrammatic representation of the plan on 
 which artificial molars have generally been 
 shaped in the past. The broad surfaces can- 
 not cut up foods to isolate the cells. They 
 can be approximated only by the exercise of 
 great force. 
 
 A. A cross section of Trubyte lower first 
 and second molars showing five ridges in 
 each tooth. B. Ridges and facets in Trubyte 
 upper and lower molars opposed. C. The 
 cross sections shown above were made at the 
 dotted line in this figure. 
 
 Illustration No. 38 
 
"A JSTeW CliASSIFICATION OF ToOTH FoEMs" 
 
 4th. As the three primary forms of human teeth are coromon in 
 all races, therefore a system of artificial teeth founded on these 
 primary forms is equally suitable for all races of men civilized or 
 savage. 
 
 5th. As investigation shows that there are but a few characteristic 
 forms of human faces which can all be grouped in a series of a dozen 
 or less, to which groups all slight variations in form may be referred, 
 therefore a few forms or types of teeth, very carefully designed and 
 modeled to harmonize with the more characteristic forms of faces, 
 are immeasurably better suited to the production of natural and artistic 
 effects in dental prosthesis than any number of moulds produced 
 indiscriminately and without any knowledge of the above-mentioned 
 fundamental facts. 
 
 6th. A close study of the relationship of the contour lines of the 
 teath and face has enabled me to design artificial teeth that will be 
 found to give more perfect harmony with many faces than did the 
 natural teeth of that subject, the reason for this being that the laws of 
 heredity as exhibited in mixed races rarely permits a perfect harmony 
 in the different features of the body. 
 
 7th. The arrangement of this system of teeth into classes and 
 groups based on jSTature and corresponding with the forms of faces for 
 which they are designed, both being shown in illustrations placed side 
 by side, enables the dentist, aided by the very clear and simple table of 
 classification, to select the teeth best suited for any case with an ease, 
 economy of time, and certainty of results never before approached. 
 
 8th. A method of finishing the labial surfaces of the plaster models 
 for artificial teeth, and the accurate transfer of this to the moulds in 
 which the teeth are cast, has been devised with the result that a perfect 
 imitation of the surface texture of a fine natural tooth has been secured. 
 The esthetic value of this one feature of the new system of teeth is suffi- 
 cient to merit the indorsement of all progressive dentists. 
 
 9th. A method of coloring porcelain teeth has been worked out by 
 strictly scientific methods, based on a color analysis of the finest natural 
 teeth, and applied to the Trubyte System of teeth, producing beautiful 
 natural effects far beyond anything previously accomplished. 
 
 10th. My associate in the work of producing the Trubyte System 
 of teeth. Professor Dr. AHred Gysi, has given years to the study of the 
 mechanical principles involved in mastication and to all the conditions 
 necessary in artificial teeth for the highest possible efficiency in the 
 performance of this function. Basing his work entirely upon nature, as 
 I have in designing the forms of teeth, he has recognized that the con- 
 ditions under which mastication must be performed with artificial 
 teeth are totally different from those which obtain in the use of natural 
 
 75 
 
J. Leon Williams, D.D.S. 
 
 teeth. He has therefore adapted the natural cusp, groove and sulci for- 
 mation in the relations of the upper and lower teeth in such a way as 
 to secure far greater efficiency in mastication thanwould be possible even 
 with the finest natural teeth if inserted on plates as artificial dentures. 
 While the cusps are high and the fossiP and sulci deep in the new teeth, 
 thus making them very effective in holding, tearing and grinding food, 
 yet the ''bite" is actually more shallow than in efficient natural teeth 
 or in other porcelain teeth which manifest even slight efSciency. This 
 permits easy and comfortable gliding of the upper and lower teeth on 
 each other in lateral and in backward and forward movements. 
 
 With all of these advantages of scientific form and accuracy in all 
 their features the new teeth will be found, when the dentist is once accus- 
 tomed to them, more easy to arrange on any form of articulator than any 
 teeth heretofore made, the perfection of the relations of the upper and 
 lower teeth showing at once exactly where they should be placed. 
 
 Gentlemen, speaking not only for myself, but for all who have 
 taken part in this work, I am expressing my most sincere convictions, 
 when I say that no more concentrated and determined effort has ever 
 been made in the interests of dentistry than that involved in this new 
 system of artificial teeth. 
 
 Scarcely more than the bare results and conclusions could be em- 
 bodied in this presentation of the subject. A detailed account of 
 all the experiments made, of all the scientific work done during the 
 past four or five years, would fill a large volume. 
 
 It has been our firm determination to do this work so well that it 
 should be done for all time. It has been our desire and intention to set 
 the standard of prosthetic dentistry so far above the position it has hith- 
 erto occupied as to make it impossible from this day henceforward for 
 any self-respecting dentist to continue working in the old ways and 
 with the old materials. 
 
 76 
 
]\10LAK BLOCKS. 
 
 
 OCCLUSAL 
 
 ^IH^^iiw^**V 
 
 CERVICAL^ 
 
 LINGUAL 
 
 Dr. Gjsi has invented 
 a new form of bicuspids 
 and malars which I feel 
 sure will be found most 
 convenient in practical 
 work. He calls this form 
 Molar Blocks, because the 
 bicuspids and molars of 
 each side are joined into a 
 solid block. 
 
 The Molar Blocks dif- 
 fer in very important ways 
 from the gum blocks to 
 which many of us have 
 been accustomed. Those 
 gum blocks were designed 
 for occlusion but not for 
 articulation, and it is 
 pretty nearly inipossil;)le to 
 articulate them. These 
 Molar Blocks are designed 
 to facilitate articulation, 
 and to that end Dr. Gysi 
 has worked out the com- 
 pensating and lateral 
 curves in the occlusal sur- 
 faces, so that when set in 
 
 the occluding position the work of articulating the teeth is already well 
 
 advanced. 
 
 Dr. Gysi states that it is most advantageous to offer these blocks 
 
 in the curves common to the average inclinations of the condyle paths, 
 
 because a slight inclination of the entire blocks adapts them to any 
 
 greater steepness of curves. 
 
 These blocks may be articulated in much less time than single teeth. 
 
 It is much easier to perfect the articulation in its finer details, because 
 
 single teeth cannot move out of position, and because the proper relations 
 
 of the several teeth are already determined. 
 
 The occlusal surfaces of these blocks exhibit the same characteristics 
 
 as the single teeth and are efficient in the same unusual degree. 
 
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