Where extraction comes to be demanded, it is performed by means of instruments adapted to the special peculiarities of the tooth requiring removal, or to the circum stances iu which it exists. The great matter is, that each tooth should be extracted in accordance with its anatomical configuration; and to accomplish this, of course, requires an intimate knowledge of the natural form proper to each of these organs individually; without this, it is impossible to extract any tooth upon a correct principle. The tooth is grasped, as far as the instrument can be made to do so, by that portion of the root or fang which just emerges from, or perhaps which is just within, the socket; it is then loosened, not exactly by pulling, but rather by moving it in a lateral or in a rotatory manner, in strict accordance with the respective character of fang possessed; and finally, on its being thus detached from its connection with the jaw, it is, with very little force, easily lifted from its socket.
Anaesthetics are employed in the extraction of teeth in the same manner as for other surgical operations, where it is desirable to abolish pain. Ether and chloroform are the"only agents of this nature which have as yet been found generally fit for prac tical application in any operation of a prolonged character. Chloroform tends to depress the circulation when far pushed, and in this way should be watched with care during its administration. Ether, again, has little of this tendency, but requires larger time to induce insensibility, is more exciting and persistent in its effect, while the odor of this preparation remains about the patient for hours. Both of these agents are liable to occasion sickness, and as a variety of accidental and collateral difficulties may arise during their exhibition, they ought not to be given by inexperienced hands.
An anaesthetic proposed at the end of the last century—namely, nitrous oxide or laughing-gas, has been revived, and its application in dental surgery has been of much service, answering all the purposes of chloroform or ether in short operations. Like these, it requires careful employment, and in some cases it would better be avoided if possible—such as in elderly patients of a full habit, or those who may have suffered from any lesion of the nerve centers, from haernoptysis, etc. Other modes of induc ing insensibility, local or general, have been proposed from time to time, but one after another has been abandoned as unserviceable. All over the world quack nostrums are found for rendering this operation painless; these, however, do not demand considera tion here, as had any one of them afforded the least chance of success, it long ago have been gladly welcomed and generally adopted by dentists.
2. Mechanical Dentistry.—The manufacture of artificial teeth, and other matters comprehended in mechanical dentistry, involve many subjects of which no adequate Or satisfactory idea can be conveyed by mere description. Nothing beyond a mere outline of the materials employed and the leading processes involved in this branch of art, can be given without practical illustration. The various conditions of the mouth requiring the adaptation of artificial teeth, range from cases where only one tooth may be wanting, to those where not a single tooth remains in the jaw, above or below. Accordingly, artificial teeth are spoken of as partial or complete sets—a partial set being one for either upper or lower jaw, where some of the natural teeth still remain; tt complete set being one for either jaw, where none are left, or for both jaws, when both are in such circumstances.
The simplest form of partial sets is what is termed a pivoted tooth. This is an artificial tooth fixed in the mouth upon the fang or root of one whose crown has been lost by decay or otherwise. The mode of procedure is as follows: An artificial tooth, as near as possible to the color and form of that to be replaced is selected. This artificial tooth may be either the crown of a natural human tooth corresponding to that lost, or one made in imitation of this, in a species of pottery-ware, and by a process much too long for detail. in this place. Such mineral teeth, as these last are termed, arc manufactured on an extensive scale, and sold ready for use to dentists. A tooth of either kind, then, being selected, is accurately fitted to the root remaining in the mouth, and, by means of a gold pin, adjusted to, and inserted into the open central canal existing in the root—the other extremity of this gold pin being attached to the substitute tooth—the whole is fixed in its natural position, in a manner that renders detection almost impossible.
When more than one tooth is required, and occasionally even where only one is necessary, a somewhat different contrivance is had recourse to. What is called a
" plate" requires to be fitted to the gum and remaining teeth in so precise and perfect a manner as to lie quite firmly and steadily in its place, and to which the artificial teeth required are subsequently fixed, This "plate" is frequently made of gold, silver, or platinum plate, of the thickness of card-board, in which case, the name of " plate" is used in its literal signification. But such plates may be made of other substances besides those of gold, silver, etc., such as the ivory of the walrus, or the hippopotamus's tusk, formerly used, but now almost entirely superseded by vulcanized caoutchouc (q.v.) or vulcanite. The first step in any of these processes is to obtain an exact model of the gum and other parts upon which the plate is to rest. This is obtained by introducing bees-was, or gutta-percha, or other modeling compound, softened by previous heating, into the patient's mouth, and pressing it forcibly upon those parts of which an impression is desired. On remov ing the wax or other substance from the mouth, Paris plaster is poured into the mold thus procured, and on its hardening, or " setting," this plaster-cast presents an exact counterpart of the gum. It is upon this plaster-model that all the subsequent operations are performed in fitting the artificial set. The following is a very brief sketch of the principal steps in working each of the most ordinary methods employed for these purposes: Metallic-plate Sets.—Where the framework lying upon the gum is to be of gold or silver plate, or the like, it is necessary to procure, Lesides the plaster-model, a metal one. This metal-model is generally cast in zinc, gun-metal, or some such material; and a counter-model of a softer metal, generally lead, is taken from this again, so that a complete pair of dies is in this way procured. The gold or other plate, cut of a con venient size, is then stamped between the two metallic dies, and so made to assume the precise form desired. It is then trimmed, and any more delicate adjustments made upon it, such as soldering bands or clasps round those parts where it is to embrace any teeth remaining in the mouth, and finally completed by having the individual artifical teeth added to it, and adapted to the comfort and convenience of the wearer. The mode of fastening the teeth to the plate is in one of two ways. One kind of teeth have a tube extending along their whole length, and these are fastened by means of a pin fixed to the plate, upon which the tooth is secured by this pin passing up the tube alluded to. The other kind are provided with short platinum pins, fixed in the material of the tooth during its manufacture, to which pins a piece of gold or other plate is soldered, or a mass of gold fused upon them, and this, again, soldered to the framework of the set itself, wherever they are required.
Vulcanite Sets.—The first step in the manufacture of a vulcanite set of teeth is to snake a pattern set in wax, with the mineral teeth constructed for the purpose, and which are to be used in the piece when it is finished, fixed in the wax; the whole con stituting, in short, an exact facsimile of what the completed set is intended to be. This pattern set is, of course, made upon and fitted to the plaster model, and is adjusted to the wearer's mouth precisely as if it were the set to be worn there. When everything is thus prepared, a duplicate of the wax-set is made in vulcanite—the vul canite replacing the wax, and the mineral teeth being retained as they were. The process by which the vulcanitd is made to take the place of the wax consists in imbedding the pattern set in Paris plaster, so that the mold of it, thus secured, may be separable into at least two parts. On these being taken asunder, the wax of the pattern set is melted out with boiling water, leaving the teeth in situ. The wax is then replaced by raw vulcanite, which, on the mold being reclosed, is subjected to the usual process of vulcanizing.
The foregoing description comprehends most of the operations connected with surgical and mechanical dentistry. For a more detailed account of them, as well as the discussion of many minor points connected with the subject, we must refer to the numerous and beautifully illustrated works specially devoted to such matters, lately published both in this country and America; of these, Mr. Tomes of London's Dental Surgery; Dr. Smith of Edinburgh's Handbook of Dental Surgery, published by Church hill, London; Taft's Operative Dentistry, and Richardson's Mechanical Dentistry, both published in America; Oakely Cole's Dentistry; etc., deserve to be specially mentioned as among the latest and best works on the subject.