TEETH, CARE OF.—In order to preserve the teeth as long as possible, and render the gums healthy and firm, due attention should be given to the cleaning of the mouth from the very beginning. The baby'S mouth should be cleansed every day with a pledget of cotton dipped into a weak solution of boric acid. As soon as the teeth appear (usually at the beginning of the seventh month) they should be used. The child should not be fed exclusively on milk and paps and other soft foods, but should be given slices of bread, and not be allowed to reject the crusts. It is just these coarse articles of food which are necessary to develop and strengthen the gums. Chewing increases the circulation of blood to the organs of mastication, and the teeth thus receive more nutriment and become stronger. A thorough utilisation of the milk-teeth exerts a beneficial influence on the second and permanent set of teeth. The gums become firmer, and have greater power of resistance against injurious processes.
The cleansing of the child's mouth is of the greatest importance in order to prevent the accumulation of particles of milk or other food ; for, if such substances be allowed to remain, they will surely give rise to thrush and to digestive disturbances (see NURSLING, CARE OF). The proper care of the mouth also insures healthy gums, and the child will bear the eruption of the milk-teeth without any disturbances. As soon as the milk-teeth begin to appear, they must he rubbed clean every day, preferably with a piece of cotton wound around a finger and dipped in a weak solution of boric acid or of listerine. When the milk dentition, which consists of twenty teeth (ten in each jaw), is completed, a soft tooth-brush should be used. Neglect of the daily cleansing will cause milk and pap remnants to be deposited between the teeth. By the action of moulds, the sugar and starch contained in these remnants are transformed into lactic acid, which destroys the enamel of the teeth and causes them to decay. This condition, if progressive, gives rise to considerable pain. In order to avoid these harmful consequences, it is advisable to let a dentist examine the child's mouth twice a year. If lactic acid has formed on the teeth, it should be removed ; and
if carious spots exist, the cavities should be filled. If this be clone in time, the dentist's work is almost painless. It is essential that the milk-teeth he kept in a healthy condition. If they be treated carelessly and allowed to decay, the permanent teeth will suffer in consequence. They will usually break through the gums with small black spots, which indicate faulty enamel formation. It is a notorious fact that 99 per cent. of school-children have poor teeth owing to neglect on the part of the parents.
When the permanent teeth appear, particular attention should he paid to their proper care. The first permanent tooth usually appears in the seventh year. The milk dentition consists of twenty teeth, five in each half of each jaw (two incisors, one canine, and two milk-molars) ; while the permanent set contains thirty-two teeth, or eight in each half of each jaw. The names of these permanent teeth are as follows, the right time of the eruption of the separate teeth being given in parentheses : two incisors (8th and 9th year) ; one canine (between nth and 15th year) ; two premolars (between loth and 15th year) ; and three molars (the first appearing at the 7th year ; the second between the 13th and 16th year ; and the third, which is called the wisdom-tooth, between the iSth and :loth year). From this it will be seen that the first permanent tooth to make its appearance is the first molar—the sixth tooth, counting from the centre of the jaw. This tooth is often taken to be a milk-tooth ; and on the erroneous supposition that it will be displaced by another tooth, its care is often neglected, so that it decays in a comparatively short time. It should, therefore, be remembered that this is a permanent tooth, which will not be replaced when lost. It is the largest tooth in the mouth, and the best masticator ; and during the period of change it has to perform the greater part of the work of chewing.