In spite of proper care, the gums recede in old age ; and the teeth, losing their support, fall out. In some persons the teeth begin to loosen at the age of forty, while others retain a complete set of teeth until the age of sixty or even seventy.
Careful dental treatment is absolutely necessary in order to remedy the injury wrought by caries. If the cavities be filled while they arc still small, and before they have become painful, the treatment will cause but little pain. Before filling the cavity, it is necessary that the diseased tissue be removed. This will generally cause some pain ; and it is safe to say that in many cases dentists who perform this operation painlessly do so at the sacrifice of thoroughness. If diseased tissue be allowed to remain in the cavity, it will sooner or later give rise to further decay. A conscientious dentist often finds only one cavity to fill, where a superficial bungler will find two or three (see Fig. 417). The work of a dentist, therefore, should not be judged by the number of fillings made, but by their quality. The choice of the substance to be used for the filling should be left to the dentist's judg ment, for while he is preparing the cavity he is able to decide whether a filling of gold or of an amalgam would be the more suitable. If an amal gam filling be used, its surface should be thoroughly smoothed (polished) as soon as it has become hard, as this will greatly increase its durability.
Inflamed pulp cannot be preserved, but must be deadened by means of some corrosive substance. If properly done, this is an almost entirely pain less procedure. After a day or two the nerve generally becomes devoid of sensation, whereupon it is removed and the cavity filled. If this removal of the nerve be neglected—as is often the case with some bunglers in dentistry --an inflammation of the root membrane results. Teeth in which the pulp is already decayed, as well as firm and healthy roots, need merely to be filled after thorough cleansing and disinfecting of the root canals.
The extraction of a tooth becomes necessary when the root is decayed beyond possibility of preservation. Food remnants and mucus can never be entirely removed from hollow roots and stumps. These are, therefore, a constant menace to the healthy teeth, and are frequent causes of disease, particularly of stomach troubles. The supposition that a tooth should not be extracted while the gum is swollen is a wide-spread but erroneous im pression. The diseased tooth is the cause of the swelling, and the latter
recedes when the former is removed. Timely extraction of a tooth obviates the necessity of draining off the accumulated pus by incision into the gum. No tooth, however, should be extracted unless it is absolutely impossible to preserve it, since its removal often renders the corresponding tooth in the other jaw unfit for chewing (see Figs. 418, 419). For this reason it is often necessary to provide an artificial tooth in place of the one removed.
Artificial teeth are nowadays made with a high degree of perfection. If, after the loss of the crown of a tooth, it is still possible to preserve the root, the latter may be used for the support of an artificial crown made of porcelain or of gold. Bridge-work is a combination of several crowns, forming a single apparatus, which is made without a plate. and fastened to two or three supporting roots. Natural teeth which are filled, or pro vided with new crowns, are much more useful for mastication than are artificial plates, although the latter are very useful when the roots are abso lutely beyond preservation. These artificial plates are made of gold or of indiarubber. Before inserting the artificial plate, the decayed roots must be extracted ; for there is no filthier and more unhygienic habit than wearing an artificial plate over decayed, unfilled roots. The majority of people do not feel the want of artificial teeth until visible front teeth are gone, and usually wish to have only these replaced. It should be remembered, how ever, that artificial teeth serve not only to hide defects in appearance, but also to promote mastication. For this reason, not only anterior, hut also lateral teeth should be replaced when necessary. The effect of missing teeth on the clearness of speech has been discussed in a preceding paragraph of this article.
Artificial plates must be kept scrupulously clean, so as not to become a source of infection for the remaining natural teeth. It is advisable to cleanse the mouth and the plate thoroughly after each meal. At night the plate should be kept in a vessel filled with some antiseptic fluid, such as a boric acid solution.
TEETHING.—See NURSLING, CARE OF ; TEETH, CARE OF.