ARTICLE VI.

NEW METHOD OF MOUNTING AN ARTIFICIAL

DENTURE.

BY H. W. HOWE, D. D. S.

Without entering into the discussion of the relative values of the different bases for artificial dentures, we assume that an incorruptible metallic one is the best. The two metals most acceptable are gold and platinum, and while the platinum plate with its continuous gum is the most artistic, still a case can be mounted on gold by a somewhat new method, which has all the merits of continuous gum except the gum color. It is a description of this process to which I invite your attention.

The impression casts and dies are obtained in the usual way, and after the plate has been swaged and articulation taken, the teeth, which must be of the recently introduced countersunk pattern, are arranged in their desired position and wax built about them in such a manner as shall best restore the contour of the face. After the teeth are in position and the wax well smoothed to the shape wanted in the finished case, carefully remove each tooth, partially fill up the depressions left in the wax, leaving sufficient rim to show where each tooth belongs. Now varnish the whole, and when dry take an impression of the palatine surface in sand; make dies of this surface, and stamp gold plate of same gauge as the original plate. This piece of gold will cover the wax on the palatine surface. After filing that portion of the rim that comes next the teeth to correspond to their interstices, the impression material is removed and the rim and plate soldered together; the holding of the two together can be greatly facilitated by riveting with fine gold wire, which after the soldering can be filed away. There is little danger of the plate warping, if it is heated uniformly with a blast blaze. It should, in soldering, rest steadily on

a piece of charcoal cut to fit it. After the soldering, the plate is filed and polished, and then replaced upon the articulation. Each tooth is now fitted to its position and rearticulated. The case is then flasked teeth down, exposing only a small portion of the wax rim. The procedure is now the same as in rubber work, the wax is boiled out and the space packed with pink rubber. Much artistic talent may now be displayed in the carving of the gum. After polishing and bleaching, the case is finished. It will rival continous gum for beauty, while it is far stronger and more serviceable. A broken tooth is easily replaced in oxyphosphate of zinc, in ten minutes.

The writer offers this method to the profession, believing it a substantial improvement on what has heretofore been attempted in gold work, and hopes it will meet with their approbation.- Western Dental Journal.

ARTICLE VII.

RUNYAN'S METHOD OF BRIDGE-WORK.

BY H. W. RUNYAN, D. D. S., EATON, OHIO.

There is no doubt that bridge-work is very valuable in many instances for partial dentures. But the great cost of the gold process places it within the reach of comparatively few, while there are fewer practitioners of dentistry that thoroughly understand the swaging and soldering of gold that is necessary in the construction of the gold bridge-work. The method here described will place it within the reach of all who can afford a plate of any kind, and it can be constructed by any one capable of making a vulcanite plate, and I think it will last as long as any bridge-work, or as long as the roots, to which it is attached, will last.

Process of Construction: For a case where the four incisors are missing and the cuspid roots remain:—

After cutting the cuspids down to, or a little above, the margin of the gum, prepare by drilling out the canal with an inverted cone bur, and then a pointed fissure bur. By so doing, a perfect funnel-shaped canal is formed, which gives strength to the work, and facilitates access to the end of the root. Take a platinum bar long enough to reach from one root to another, and bend at right angles to form the pins. Now set the bridge support in place, after bending to conform with the gums; and take the impression and articulation, Make the model, place on the articulator and wax on vulcanite teeth. Remove from the articulator, flask and vulcanize, after covering all the rubber with vulcanizable gold.

Gum teeth can be used for the bridge between the roots, if the alveolar process has been absorbed very much. After vulcanizing, clean up and fasten in by placing a little cement on the pin that extends into the cavity formed by the fissure drill. The rubber will fill that part formed by the inverted cone.

Use the best rubber, run the vulcanizer up slowly to 300° Fah., and vulcanize for one hour and fifteen minutes. You will have "a thing of beauty, and a joy" to your patient and yourself.-Ohio Journal of Dental Science.

ARTICLE VIII.

EVOLUTION IN PATHOLOGY.

MAN'S LOST INCISORS.

In his lectures on "Evolution in Pathology," delivered at the Royal College of Surgeons of England, Mr. J. Bland Sutton, F. R. C. S., referring to the suppression of parts, said that one of the clearest instances of suppression, and at the same time one capable of indisputable demonstration, is connected with the disappearance and occasional reappear

ance of a third incisor tooth in man. The matter was first worked out and announced by Professor Albrecht (now of Hamburg) in quite a number of papers, that normally man inherits three incisors on each side in the upper maxillæ, but during development the middle (second) one of the three is suppressed. In many cases of cleft palate, however, more room is afforded, and the usually suppressed tooth attains a functional condition. The question was one of importance, and I was able in a paper read before the Odontological Society of Great Britain in December, 1884, to confirm this part of Albrecht's observation. Professor Sir W. Turner, a month later, adduced also confirmatory testimony in the Journal of Anatomy and Physiology, and the last contribution in this direction is by Windle and Humphrey in the same journal. A careful analysis of the facts shows, beyond all doubt, that in the usual course of events an incisor tooth is suppressed in the upper maxilla of man; the only point admitting of any latitude of opinion is whether the missing tooth is the second or third incisor. As the case stands at present the balance of opinion is in favour of it being the second.

We must not forget, however, that supernumerary teeth are found in other situations than in the incisor series; indeed, they may occur in almost any part of the dental arch, and may vary in character from a perfectly formed enamel-coverea tooth to a tiny conical mass of dentine. In determining whether an extra tooth is a supernumerary one or not, we must also take into consideration the fact that an excess in the number of teeth is occasionally due to the retention of one or more milk teeth. In order to comprehend the true significance of supernumerary teeth, it is necessary to bear in mind the morphology of these organs. In their essential features the teeth of a shark agree with those of a mammal, and in their development as calcified papillæ of the involuted epiblast in the buccal region-the stomodæum-the two forms are in perfect harmony. In the case of the shark almost the whole of the mouth is beset

with teeth, whereas in mammals they are normally restricted to certain very definite tracts. An unprejudiced survey of the facts ought to convince us that though the teeth of mammals are thus kept within narrow limits, yet the papillæ in the immediate vicinity of these teeth territories are potentially teeth, and it is perfectly consonant with what we know of the principles of atavism that these papillæ should occasionally declare their ancestry by developing as rudimentary, or even perfect, teeth. Nor is this form of atavism limited to this particular region; for, inasmuch as teeth are modified papillæ of the skin or integumental covering (and this may be absolutely demonstrated in the case of the young of the dog-fish, in whom the various stages may be clearly traced from placoid scales to teeth), so in those remarkable teratomata arising in obsolete canals lined with epiblastic tissues, calcified papillæ (teeth) make their appearance. Dentine and enamel are tissues which exist in scanty proportions in man, yet they formerly occurred in great abundance in the remarkable mailed-ganoids which are encased in an elaborate armour of these very extraordinary tissues.

If we admit the above opinions, then a rational explanation is forthcoming of certain interesting pathological conditions which occur in the mouth. For instance, some form of odontomata may be considered as aberrant involutions of buccal epiblast and papillæ; the view is supported by the fact that this variety of neoplasm occurs in many mammals. There is also good evidence to support the view *hat the milk dentition is to be regarded as a set of teeth appearing in obedience to the law of inheritance. In many mammals they are, like the lanugo of the human fœtus, shed before the embryo quits the uterus. If supernumerary teeth can be regarded as atavistic, then we must consider certain pre-calcific stages of teeth in the same light; for instance, in the early stage a tooth consists of an up-growing papilla capped by a down-growth of epithelium. Suppose the development to advance no further, but growth to con