T H E PA R T IA L D E N T U R E * By HERBERT E. KING, D.D.S., F.A.C.D., Omaha, Nebr. N presenting a paper on the rather broad subject of “ P artial D entures,” I hope that it will be possible to give a general review of the topic, and to select certain good points or bad of the various different methods of restoration of missing teeth. So often, the subject has been presented with the seeming pur pose of advancing or explaining some particular method of technical proce dure. M ay we first define the subject, though in a true sense any restoration of missing teeth short of full dentures could be called a partial denture. Ira G. Nichols, in his recent book, “ Prosthetic D entistry,” gives this definition: “ Partial dentures are removable appliances for the restoration of part of the natural teeth and related tissues.” T h e denture depends for its support on both teeth and mucosa and, seemingly by common con sent, the field has been divided in recent years into removable bridges and partial dentures. Sometimes, the term s are used almost interchangeably, and we suspect that sometimes, because it has the better sound, the name removable bridge may be used to impress on the patient th at he is not to have a plate or denture but something much more modern and up to date and, of course, more expensive, than the older appliance. T h e use of the terms, then, has not be
*Read before the Section on Partial D en ture Prosthesis at the Seventy-Third Annual Session of the American Dental Association, Memphis, Tenn., Oct. 21, 1931.
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come definitely fixed, but a generally accepted difference is that a removable bridge depends wholly, or at least for the m ajor portion of its support, on the re maining natural teeth, while a partial denture depends for its major support on the mucosa or the soft tissues. I shall not attem pt to draw a definite line as to where the choice should be made between fixed and removable bridgework, for it is largely a m atter of judgm ent and of individual choice on the part of the operator as to just where the one or the other may be deemed desir able. W h at we do wish to say is that, all too often, a decision is made from indi vidual prejudice rather than from sound judgment. W e may allow ourselves to become 100 per cent operators, a very difficult ground to stand on. I t is not well to say, “I would never make a fixed bridge,” or “I do not believe in removable bridges.” As an illustration, I have noted in a recent textbook 1 a cast shown having missing a single lateral incisor. Quoting the text, we find, “A difficult type of case to replace w ithout extensive mutilation of the proximating teeth, as is frequently resorted to when a fixed bridge is ap plied.” And yet, in the illustration of this case as completed as a removable bridge, there were inlays placed in the adjacent cuspid and central incisor and in a bicuspid and on the opposite side in 1. Ed. 4.
Prothero, J. H .: Prosthetic Dentistry,
King— T he Partial Denture
N aturally, there are good points on both sides of the question and also there are enthusiastic and sometimes rather preju diced advocates for their particular method to the exclusion of the other. I t certainly does not seem reasonable to make the extensive preparation neces sary for the average internal attachment in a tooth that has not already a filling or caries in the surface to be used. A n unbroken enamel surface is a valuable asset for any tooth. I t would be in my own mouth, I believe. W here there are previous preparations or carious areas that may be utilized for inlays for the attachments, the internal type might be the most logical, and, when properly made, they are a beautiful and practical means of restoration. As to the choice between the various patented or ready made attachments on the market for use in these cases: this must be left to the individual operator. T here have been many of these appli ances brought to our attention, some relatively very complicated in their mechanism. Simplicity and durability should be the guiding principle and, for the average operator at least, a highly specialized technic makes the use of some types very difficult. Exact parallelism and precision are very attractive in an ideal but rather difficult of attainment. Simplicity always reduces the number of necessary adjustments in the future maintenance of an appliance. As one patient expressed a justified criticism of a case: “I t is like an old type c a r : I don’t dare get too far from a service station.” As to the removable bridge with at tachments of the external or clasp type, w hat do we find to condemn or criticize ? M uch has been said and w ritten as to caries occurring under clasps and there 2. Tylman, S. D.: Dent. Digest, 36:354 has undoubtedly been much damage re sulting therefrom. W hen the cast clasp (June) 1930.
a molar. Four inlays were used, as well as the necessary framework, including a palate bar to connect the attachments in these inlays and a further secondary rest on a second molar. A ll this to replace one single lateral incisor. I am asking if this is not carrying an idea to the point of an absurdity. M any restorations of a lateral incisor have been apparently suc cessful when made w ith a veneer crown on the cuspid and possibly a rest on the central incisor. T his, when cemented to place, is a restoration that is sanitary and can be forgotten by the patient. W e wonder which would be the method used if the missing lateral incisor were from the mouth of a dentist. Stan ley D. Tylm an, in a paper on “Crow n and Bridge Prosthesis ,”2 says, “T h e pro fession as a whole has been misled by the removable enthusiasts in not distinguish ing between proper cause and effect.” In my opinion, the average patient is more comfortable and is better served by means of fixed appliances, provided the teeth and tissues involved in their sup port can be kept in a healthy condition. T his proviso, the “if” in this case, is of course highly important. W ith o u t due attention to this subject, the health of the investing tissues, it would be better in many cases to place no bridge at all. W e do not mean to imply that there is no place for the removable bridge but that w ith a sane and careful study of the case in hand and a well-balanced judg ment on the part of the dentist, it will be found not always the most desirable method. T h ere are two schools of thought as to a technic for removable bridges. T h e one group employs clasps or external rests on the teeth used for support; the other, the so-called internal type of attachment.
The Journal of the American D ental Association
method was first called to the attention of the profession twelve or fifteen years ago, by D r. Roach and others, it was so revolutionary and so easily applied that many over-enthusiastic followers appar ently forgot any previous knowledge of the cause of caries. Large surfaces of the enamel were covered by the casting; the clasp itself was not even a smooth pol ished surface where it was in contact with the tooth, and the resultant decay was inevitable. T his, as we all know, brought on the reaction to be expected, and the cast clasp in the thinking of many men be came discredited. T h is was not the fault of the cast clasp, but of the men who failed to give due thought to the princi ples involved. A cast clasp was too apt to be much too large, and not enough attention was paid to either proper de sign or finish. W e believe that the care ful operator can avoid most of the faults which are all too often seen in this con nection. A cast clasp need not be much larger than the corresponding clasp made by any other m ethod; the relative strength of a draw n or a cast metal of similar composition accounting for the difference. T h e subject of clasp design is a topic in itself, but a few of the principles in volved might be mentioned. I t should be so planned that there is only the mini mum am ount of contact w ith the enamel that will give the required retention. Usually, the retention or grip on the tooth is due to that portion of the clasp at or near the ends of the clasp, and by placing these points in definite positions and relieving the remainder, we may avoid much of the danger of caries. T h e recent designs by D r. Roach of the bar clasp are a successful attem pt to follow out this principle. W here this design is
indicated, it offers a very satisfactory solution of the question. A second point in the design is a care ful study of the thing the certain clasp is expected to do. A clasp should resist cer tain forces or hold a denture against dislodgment in a certain direction. T here fore, the clasp should be planned w ith this in mind instead of, as we so often see, being so made as to cover as much of the tooth as possible. Probably onethird or even one-tenth that area of con tact on tooth structure would have been sufficient. A ll this in regard to clasp design serves only to call attention to the many details and angles having to do w ith the proper diagnosis and design of whatever type of restoration we may wish to make for a particular case. Several at tempts have been made to form a classi fication of cases for partial denture restorations and several such systems have been published. W . E. Cummer has done much good work along this line and more recently W illiam M . Randall, in a chapter in Nichols’ “Prosthetic D en tistry” has given a sane and reasonable classification, based upon anatomic con ditions as to position and number of re maining natural teeth and upon the means of securing the necessary reten tion and balance on these teeth and their tissues. A most important consideration is the classification of the case from a more im portant standpoint, that of the patient. W e must study his general health, men tal temperament and habits of prophy laxis, before looking at the mouth or the models to make a decision as to the mechanics of the case. I wish to take the liberty to quote fur ther from D r. Randall3: 3. Nichols, I. G .: Prosthetic Dentistry, St. Louis: C. V. Mosby, 1930, p. 564.
D e Vries— M cC oy “Open T ube" Attachm ents Diagnosis literally means a comparison and study of the various symptoms gathered to gether in their mutual relationship to each other— biologic and physical— in such a man ner as to enable the diagnostician to draw cer tain definite conclusions as to the best method of treatment or procedure in handling the case in the surgical, therapeutic and restora tive measures— given separately or collec tively. T he accurate and final diagnosis for par tial denture cases is more complicated in many respects or at least presents a greater variety of problems in each individual case than in full denture service. The conservation of the health and normal function of the remaining natural teeth and
their supporting tissues is a more serious and, in many instances, a much more difficult obstacle than the designing and constructive procedure of the restoration. It is our sincere belief that there is no field of dental practice where it becomes more essential to more closely and accurately relate the biologic and physiologic factors to the physical or mechan ical as in the choice of retainers and their relation to each other— the connectors and bases and the varied directions of the lines of stress of mastication through the artificial and natural teeth to the end that the coordinate result w ill both conserve the health of re maining natural teeth and the adjacent tis sues and render efficiency in esthetics and mastication.’
T H E O R Y A N D A PP L IC A T IO N OF T H E M cCOY “O PEN T U B E ” A T T A C H M E N T S* B y B . G . de V R IE S, D .D .S ., M in n e a p o lis, M in n .
I N any program devoted to orthodontia,
the subject of appliances will always play an im portant part. I t is true that frequently undue emphasis has been placed on the mechanical aspect of our profession, but, by and large, mechanics will always occupy a large place in our consideration of the subject. T his is read ily understandable, if we consider the status of the operator. H e proves of value to the community only in direct proportion to his ability to solve the problems before him. In other words, his efficiency is measured only at the “oper ating point,” the point of his contact with the public at large. T h is point finds him in the position of applying practically the means which shall put to the test the sum of his accumulated knowledge of the *Read before the Section on Orthodontia at the Seventy-Third Annual Session of the American Dental Association, Memphis, Tenn., Oct. 21, 1931.
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subject. I t is here that the mechanical aspect steps firmly into the picture. Being the most tangible of all of the other con tributing factors, is it any wonder that it receives a tremendous amount of at tention ? Being so tangible, there is little wonder that mechanical measures fre quently receive more credit or more abuse, as the case may be, for success fully discharging their duty or miserably failing to do so. T he. difficulty has been that mechanics has usually been consid ered too empirically, too inflexibly, as a thing apart. I t may seem incredible, but it is possible that orthodontic treatm ent at times has been more or less successfully consummated in spite of the appliances. W e can conceive of conditions of this sort in which the array of “machinery” was far in excess of the demands for it; and, of course, the converse is also true. I believe that empiricism in orthodon tic appliances is rapidly giving way to a