The Relation of Caries Activity to Lactobacillus Counts and Types and to the Fluoride Content of Drinking Water

Abstract

197 children whose drinking water contained 1 ppm F, and 186 whose water contained no F were examined for decayed teeth and surfaces. Lactobacillus counts and the predominating biochemical types in the saliva were determined also. All children were aged 11-14 years. The dental examinations were repeated, on most, one year after the first examination. The incidence of caries and the attack rate the following year were much higher in the no-F group. Those with high lactobacillus counts had a higher incidence of caries than those with low counts, and those whose saliva had a rhamnose-fermenting type predominating had a higher incidence than those with other biochemical types. A greater avg. number of decayed surfaces per child was found in those children in the no-F group who had low counts and a rhamnose-fermenting lactobacillus in the saliva than in those with low counts and another type. The difference was less when the counts were high. In the F group, a greater avg, number of decayed surfaces were found in those with the rhamnose-fermenting type only when the counts were high. F did not appear to influence the flora since there were approx. the same percentage in each group having a given type of lactobacillus.