For an alkaline dentifrice, there is nothing better than lime-water, made from coarse, unslaked lime. Alkaline washes are very superficial in their action, however, while fruit acids curdle and thus render removable the mucin plaques and prevent the formation of tartar. They also cleanse the tongue and membranes of the mouth generally, which may be important sources of infection. These acids are found in grape-juice, orange-juice, apples, and vinegar. Such mechanical cleansing is particularly important before retiring, as it is usually during the night that the most damage is wrought. [Sidenote: Erosion] The advice of the dentist should be sought as to the condition of the teeth, especially as to whether there is any erosion or destruction of enamel, before using either acid or alkaline washes exclusively. [Sidenote: Periodic Examination] Periodic examinations and cleanings by the dentist are the only safe measures. If the dentist has facilities for giving _preventive_ treatment by specially cleaning the teeth, he should be visited every other month. If such a program is adopted, it will generally be found unnecessary to visit him for any other purpose. [Sidenote: Saving Teeth] Some dentists and physicians have until lately given too much attention to the saving of teeth, without fully realizing the dangers of infection from the mechanical devices employed. The teeth should not be extracted on mere suspicion and without proper effort to save them, but it is far more important to save a heart or a kidney or a set of joints than it is to save a tooth. This is not to say that all bridge- and crown-work is improper, but that such work should only be of a character that will permit of surgical cleanliness in the mouth, and that such teeth should always be examined by the X-Ray, when there is evidence of systemic disease in order to be sure that the roots and sockets are not infected. [Sidenote: Irregularities of Teeth] In early life the jaws should be carefully examined by both dentist and doctor in order to determine whether or not the proper development is taking place. If upper and lower teeth fail to fit well together, extra strain is placed upon certain teeth and the sockets are liable to injury and infection. Faulty development can often be corrected and deformities that interfere with proper mastication and place a strain on certain teeth can thus be avoided. [Sidenote: The Temporary Teeth] The temporary teeth should not be allowed to be removed by decay. Thorough dental and home care should prevent this. If cavities form, they should be filled under proper precautions and the teeth should be saved until the last minute, unless they are causing infection. [Sidenote: Teeth and Infectious Diseases]