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is inhibited, malnutrition and unbalanced waste-removal follow, vital resistance is lowered, and any break in the integument at the subgingival space is quickly followed by infection.

Normal tissue never becomes infected. There must first occur certain changes which make the tissue pathologically receptive, as well as some break in the integument where the infecting organisms may enter. This is true in regard to the infection of tissue which supports the teeth, as elsewhere in the body. In traumatic occlusion the elastic gingival attachment of the dental ligament becomes gradually weakened, and finally literally torn from the cervical cementum, opening the subgingival space for the ready entrance of detritus. In such an environment the mouth flora find an ideal culture medium and a ready passage. Normal gingival epithelium has a very high resistance to all micro-organic life, as have all the mucous surfaces of the whole alimentary tract; but when these structures have sustained a prolonged irritation from a constant and determined pounding with every closing of the jaws they become exhausted, and the natural resistive forces are found too debilitated and disorganized to repel attack. The symptoms of occlusal trauma are to be observed in mouths perhaps years before the resistance of the investing structures have become so lowered that they become a prey to infection.

The mouth may at times be utterly neglected in so far as its sanitation is concerned, it may even tolerate the presence of badly fitting crown bands, with their usual accumulations of septic débris, such a state being endured for years without evidence of periclasia, but let a beautifully carved occlusal inlay or filling be inserted, where zeal for the artistic has resulted in an abnormal cusp relation, or let a piece of bridge work or a single crown be placed in such a mouth and the reciprocal relation of the occlusion disturbed, and forces are at once set up which result in tissue dystrophy and infection. This would indicate that the immunity of these tissues was sufficient in the one case, where the resistance was

high, due to the normality of the occlusal relation, and insufficient in the other, where the abnormal stress relation with its accompanying interference with coordination has reduced the tissue resistance by traumatic occlusion.

Periodontists find bridge work of every conceivable type in the mouths of their patients. A description of some of this should be suppressed, as considered unmentionable in polite dental circles; we will therefore let it pass. A reasonable percentage of this work, however, reveals at a glance that it is the work of the earnest, skilful, and painstaking type of practitioner who comprises the large majority of our profession. Let me present a typical case: Overlooking for the moment the well-nigh fatally diseased condition of the stumps which are acting as the holding abutments, let us observe the bridge itself. One can well imagine the satisfaction of the dentist when the piece was received from the laboratory quite finished and mounted upon the little plaster-of-Paris cast representing the segment of the jaws which was so generously included in the impression. One can see at a glance that the porcelain facings are not checked, nor has the solder, which has been so skilfully flowed over the backings and the conventional occlusal swagings, any pits or blowholes. The reinforcement by extra plate and solder makes the shell crowns rather difficult to remove. There is an evident honesty throughout its whole composition. The shade selection of the porcelains is excellent and these have been ground to fit the gum contour with precision. The buccal resemblance to teeth is striking. This seems as far as we can go in commendation or compliment, for the occlusal surfaces are quite untoothlike in both outline and form. lingual surface-there is no lingual surface! From the lingual cusp to the buccal cervical border there is just a smooth inclined plane to encourage the tongue in its efforts to dislodge food particles. This surface has been called a self-cleansing surface, an example of misnomer of the most pronounced type. Study models of such a case would reveal that all of the

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occlusal contact stress had been concentrated upon the bridge, for the abutments are loose and elongated, due to a thickening of the pericementum by occlusal trauma; they are also septic. It is today a professional crime to set a bridge such as I have described. Infection about the abutments must as inevitably follow in this case as in that of the tooth with a root-canal which has been filled with absorbent cotton. This particular kind of result in bridge work is the outcome of unquestioning allegiance to antiquated methods, together with a disregard and ignorance of the anatomical movements of the mandible.

The making of study models as a forecast of treatment in restoration is a common practice among many of the more advanced practitioners. These study models are typical orthodontic casts, which are occluded in their true relations. Prognosis for the necessary anatomical restorations may thus be studied at leisure, and the scheme definitely decided before treatment is begun. The taking of impressions of finished cases for the purpose of making casts for criticism of one's own results is a practice which is indulged in by a very few; yet were this a customary practice, what an infinite improvement would soon result! Diagnosis for prophylaxis in such cases as these would reveal traumatic occlusion, if present, and much harm could thus be prevented. Were the results of these failures of bridge work through this fault apparent after a few days or weeks instead of after several years.of unsatisfactory service; were the symptoms which are induced of a painful and inflammatory character from the very first, this paper would never have been written -for, like the prosthodontist, the bridge worker would have definite and immediate trouble on his hands, and the remedy would have been adopted simultaneously with its introduction into the plate work.

LIMITATIONS OF THE DENTAL LABORATORY.

The practice of employing laboratory assistants or of sending cases to the pub

lic laboratories is good, provided one obtains competent workmanship. It must be remembered that these so-called mechanical dentists can only supply technical help; that they have no academic knowledge of the anatomy of the parts which are undergoing repair, nor do they even have an opportunity to observe in practical service the appliances upon which they work. That they frequently have skill in their work which exceeds that of the dentists who employ them is obvious. But so has the bricklayer superior technical skill to that of the architect, and so it should be. That the laboratory man's results are ever a failure is largely the fault of those who employ him. It has been said of the alarm clock that to be successful with its use one must know more than the clock.

In investigating the relation of the dentist to the public laboratory I have found that it is customary for the dentist to send to the laboratory impressions which include never more than the lateral half of the jaw; that the articulator used is of the hinge principle type, or else what is known as the "back extension" is used in place of an articulator, the latter having but one movement, lifting apart as a cover lifts from a box.

It is necessary, in order to obtain results which are satisfactory, to have a full impression of both jaws, and to have the casts poured in some material which has sufficient hardness on the occlusal edges to withstand attrition while the case is being articulated. The antagonizing cast should never be made from a wax bite, but from a cast made from an impression, and the upper and lower casts then assmbled upon the anatomical articulator with the aid of the face-bow.

REQUISITES OF PERFECT BRIDGE WORK.

Bridge work should resemble the natural teeth in so far as it is possible. Correct measurements of the crown diameters should depart from the true measurements but slightly, if at all. Lingual surfaces are of greater importance to the function of mastication than the buccal and labial, and they should

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rangement of the natural teeth in their occlusal relations. Cases of unilateral deformities in malocclusion exhibit marked differences in the curve of the condyle path in this articulation. Certain maxillary habits are formed in each case previous to the loss of the teeth, and in any

There are certain names to which credit for research in this work should be given, for it is by the labor of such men as Bonwill, Snow, Gysi, and Williams particularly, and many others, that this science has been developed. writer does not claim that there has been suggested here anything original, but he does assert that the anatomical articulator has been used in these cases and found successful.

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The name of Peeso is almost as familiar to the bridge worker as is the work itself. Dr. Frederick A. Peeso has recently published a text-book entitled "Crown and Bridge Work," which is a complete working compendium for this field. If the plea which I have made here has not impressed you with the gravity of the situation, I can do no better than to quote from the writings of this master of the subject. He states:

Another fundamental to crown and bridgework success was brought to the fore when a few scientifically inclined earnest workers, in an effort to make more effective artificial dentures, began a careful study of the various movements of the mandible during mastication. The object of these efforts was to devise a contrivance to accurately reproduce these movements so as to enable the dental workman, when mounting artificial teeth, to secure a more normal occlusion. Heretofore if the upper and the lower teeth articulated

with each other when the mandible was at rest, the work was deemed satisfactory, notwithstanding that the dentures were ineffective in mastication, owing to the fact that all the teeth met only when the mandible was in the rest position. At other times but few teeth were in contact. The immediate result of these investigations was a better understanding of the mechanism of mastication, and a higher appreciation of the importance of normal occlusion that has since reached all departments of our profession.

By occlusion is understood a rubbing or grinding surface contact of all the masticating surfaces of the teeth during all the movements of the mandible, as is always the case with the natural teeth in their normal position. Articulation is a mere fitting together in one position only.

This understanding of occlusion brought to the fore an imperfectly recognized cause of failure of many dental bridges. With the mouth closed, the teeth on these bridges fitted the opposing teeth accurately, but during mastication they touched at a few points only. Except for this fact these bridges might have given many years of excellent service, but owing to defective occlusion the force of mastication was concentrated upon a few teeth, which resulted in literally pounding

the structure to pieces in a short time. In other cases the stress set up a destructive irritation in one or more of the supporting abutments, which just as surely resulted in the bridge failing. We know now that it is impossible for any one tooth to be unduly strained during mastication or other movements of the mandible if the occlusion of the denture has been properly adjusted, be it a plate, a crown, or a bridge.

This work of Peeso's is of such importance in the literature of bridge work that I will also take the liberty of quoting from this same source-from his chapter headed "Articulation." He states:

In crown and bridge work the question of the occlusion is of most vital importance, as the stability and life of the work depends to a very great extent upon its proper occlusion with the opposing teeth. In all cases of bridge work it is absolutely essential that only first-class anatomical articulators, capable of reproducing the natural lateral or triturating movements of the mandible, so necessary for perfect mastication, should be used. . . . Nearly all of the small so-called crown articulators on the market are absolutely worthless so far as securing good results are concerned. With these articulators the only movement possible is simply the up and down, or the opening and closing of the mandible. . . . In the majority of cases the face-bow should be used to serve as a guide to mount models properly on the articulator.

The time has arrived when our profession is being looked upon as a group of scientifically trained men who have as their fundamental idea the prevention and cure of all disease which has its inception within the confines of the mouth. To be accredited with less would be abbe producers of disease instead of physihorent to every ethical practitioner. To cians, to be destroyers of teeth instead of dentists, to be artisans instead of surgeons, is the very antithesis of our aspiration. So, if there has been a distressingly high percentage of failures in our bridge work, let us all get together and see that this stain on the escutcheon of the best profession in the world is wiped out. Let all among us who have at heart the high ideals of our profession either correct the practice of using a hinge articulator or quit making bridge work.

115 BROADWAY.

Indirect-Direct Gold Inlay Method.

By M. J. WAAS, D.D.S., Camden, N. J.

(Read before the Academy of Stomatology of Philadelphia, at its regular meeting, January 4, 1918.)

W

WHEN invited to appear before you this evening the suggestion was offered that I touch upon some "high point" of interest, and it occurred to me to speak about the "high point" usually present in gold inlays made by the indirect method, and a means of avoiding this.

Both the direct and the indirect methods have distinct advantages, and the method I wish to present to you, which may be called the "indirect-direct," I believe retains and combines the greatest number of advantages of each of the separate methods.

After the cavity is prepared it is given a very slight coat of lubricant, and a Roach cup of suitable size selected and trimmed to approximate shape for the case in hand. A piece of thick tin foil is placed over the hole in the bottom of the cup where the handle of the holder comes through so the impression material cannot touch it while hot and its removal from the cup after chilling is thus made easy. The shaped cup is then filled with softened impression material, preferably Lochhead's, and pressed firmly to place, where it is immediately hardened by a spray of cold air or water. This material hardens very quickly, takes a very sharp impression, and becomes so hard that one cannot remove it without fracture if there are any undercuts in the prepared cavity. Base-plate gutta-percha is then inserted in the cavity and the patient dismissed.

This impression is then invested in order that the amalgam model may be packed under pressure. A rubber ring is set on a glass slab, filled with quite

thick plaster, and the impression pressed down to place. It does not have to be invested deeply, as a small base is all we need with which to handle it. I use silver amalgam; any high-grade silver amalgam is suitable. In fact, copper

amalgam can be used and may be reused, but it is not so hard as the silver, does not stand the polishing so well, and leaves a deposit on the inlay. This deposit, however, can be removed in an acid bath; but I prefer the silver amalgam.

To begin the packing, the amalgam must be very soft, quite "sloppy" in fact, packed in small pieces, and the excess mercury removed by pressure, using bibulous paper. Drier amalgam is then added under very strong pressure and the well in the plaster filled level full. After the amalgam is hard, the rubber ring is slipped off, the plaster investment broken away, and the impression and amalgam model separated with the aid of hot water. The amalgam model is then washed with soap and water, dried, trimmed to shape, and the cavity painted with a very thin film of lubricant-castor oil 1 part, and glycerin 2 parts. then filled with inlay wax to approximately the proper shape.

It is

This wax model is now removed from the amalgam and tried in the patient's mouth, trimming with a lancet at the contact point in a compound cavity until it goes to place. The contact with the adjacent tooth or teeth is now established, and from the fit it can be determined whether the original impression was accurate or otherwise. Then ask the patient to close the teeth together very lightly, and note where the wax

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