Reduction in Experimental Rat Caries by Fluorine

Abstract

Dental research in the field of caries prevention received new impetus when Hoppert, Webber and Canniff 1 experimentally produced dental caries in 90 to 100% of their rats by feeding them a diet, which although adequate nutritionally, consisted mainly of coarse corn particles. Their hypothesis was that the corn particles became impacted in the teeth and produced decay. Lilly 2 obtained a 90% reduction in the incidence of dental decay by substituting commercial casein for the powdered whole milk (20% of the Hoppert, Webber and Canniff diet). The same year, Hodge, Luce-Clausen and Brown 3 found that the commercial casein used by them was contaminated with fluorine (0.2%). It occurred to us that fluorine might be the factor producing the caries reduction in Lilly's experiments. Two major findings in the literature support this contention : (1) clinical observations by Dean and others 4 give evidence of a reduction of caries in areas of endemic fluorisis (mottled enamel); (2) analyses made by Armstrong and Brekhus 5 have shown that sound enamel contains a higher percentage (.0111%) of fluorine than carious enamel (.0069%). Our experiment was, therefore, undertaken to compare the incidence of caries on the Hoppert, Webber and Canniff diet with (a) that on a diet in which “fluorine-free” casein is substituted for the powdered whole milk, and (b) that on the latter diet to which fluorine is added. While this experiment was in progress, Miller 6 reported that adding fluorine or iodoacetic acid to a modified Hoppert, Webber and Canniff diet markedly reduced the incidence of caries.

One hundred and thirty-five stock rats at weaning age were divided into 3 groups, separating littermates and segregating the sexes.