Tartar on the Teeth.—The accu mulation of tartar in the form of a yellowish incrustation, which is usu ally most plentiful on the inner side of the lower jaw, is almost universal. But the deposit is much more pro nounced in some cases than in others. Tartar is not only objectionable in appearance, but also tends to push the gum away from the neck of the tooth, and thus expose the soft den tine between the root and the harder enamel of the crown. In the course of years, the gum will recede so far as to allow the tooth to fall out, even if it is kept perfectly clean and is thus protected from decay. The ac cumulation of tartar cannot always be prevented by brushing the teeth, although the use of suitable tooth powders, pastes, or mouth washes will assist, but in all cases where the tartar is plentiful, the teeth should be thoroughly cleaned by a compe tent dentist three or four times year, and an astringent lotion, as a 5 per cent solution of chloride of zinc or a solution of alum in soft water, should be rubbed on the gums daily.
Aside from the advice and services of a dentist, the teeth should be thor oughly brushed and cleaned at least once a day, or better still when pos sible after each meal, and especially before retiring at night. And the teeth of small children should be cleaned for them before they are themselves old enough to form the habit of caring for them.
Permanent Teeth are thirty-two in number, or eight on each half of each jaw. Two in the front center of the jaw are called incisors or cutting teeth, and appear in the eighth or ninth year. One, next in order, the canine or dog tooth, appears between the eleventh and fifteenth year. Two next, called premolars, appear be tween the tenth and fifteenth year. Three last in the back part of the mouth are called molars, of which the first (as has already been mentioned) appears about the seventh year, the second between the thirteenth and sixteenth year, and the third, which is called the " wisdom " tooth, be tween the eighteenth and twenty sixth year.
Care of the Permanent Teeth.— Chewing dry toast, crackers, hard bread or other coarse food, greatly assists in keeping the permanent teeth in good condition. But for the purpose of dislodging particles of food, removing tartar and other sub stances a good toothbrush is indis pensable. A toothbrush having me dium soft bristles is preferable to one having stiff bristles, which may tend to injure or inflame the gum.
The shape of the brush is not par ticularly important, although the so called " prophylactic " brush assists in dislodging food from the teeth in the back part of the mouth. What is more important is the manner in which the brush is handled. In ad dition to the sidewise strokes, the brush should also be worked up and down so as to remove from between the teeth particles of food that would only be crowded in more tightly by rubbing back and forth. This is very important. The inner surface of the teeth should be brushed in the same manner, care being taken to cover, in brushing, every portion of the teeth that can be reached. The strokes of the brush should also cover the ad jacent gums. This may cause them to bleed slightly at first, but in time they will harden and become strengthened. By promoting the cir culation of blood, this will greatly improve the nutrition of the teeth and insure their permanency.
Toothpicks.—Etiquette forbids the use of the toothpick in public. But a supply of quills or wooden tooth picks of good quality should always be kept at hand at the toilet table. These should be used as frequently as possible after meals to remove particles of food that cannot be dis lodged by the use of the brush. When, as sometimes happens, the formation of the teeth is such that a toothpick cannot be used to advan tage, a piece of silk thread, such as is used by dentists, can be procured at a drug store or dentist's office. This will be found very useful for this purpose. After the use of the toothpick or thread, the mouth should be thoroughly rinsed, preferably with warm water, which has the prop erty of dissolving foreign substances to a greater extent than cold water would do. And, if possible, a good antiseptic mouth wash, such as per oxide of hydrogen, should be used.
Or use a strong solution of table salt in warm water.
Care of the Toothbrush. — After using a toothbrush, rinse it carefully, wipe it dry on a clean towel and hang it up where it will be exposed to sun light and a draught of air. Never keep a toothbrush in a closed box or hang it up in a closet. Never lay down a wet toothbrush to dry, es pecially on the back, as this allows the moisture to run along the bristles into the back of the brush, softens the glue with which they are fastened in, and causes them to decay and fall out. It is hardly necessary to say that no two persons should ever use the same toothbrush.