Clinical observation, by statistical methods, gives strong evidence that neither the bacterial theory nor the vitamin-deficiency theory, nor a combination of the two, explains the causes of caries. Sufficient time has elapsed— and an abundance of experiments have been made in research laboratories, and by practising dentists and the general public—to give both theories a fair trial. After more than twenty years of intensive education of the laity in the value of correct diet and prophylactic care, and with consequent consumption of enormous quantities of these preventives, uncontroversial statistics bring evidence that caries is more prevalent now than before these remedies came into vogue. Fundamental research on composition of human teeth (still in progress) revealed differences in fluorine contents between caries-immune and caries-susceptible teeth. Laboratory experiments on effects on animal tissues of use and disuse are in progress, and may lead to findings having significant bearing on caries.
References: numerous since 1928 ; chiefly in J. Am. Den. Assoc., 1928, 1929, 1931, 1936, 1937 ; J. Den. Res., 1933, 1934, 1935, 1936, 1937, 1938 ; J. Biol. Chem., 1935, 1937; J. Indus. Analyt. Chem. (Analyt. Ed.), 1936.