[Rate of dental caries in youths from communities of both naturally high and low, resp., fluoride content in drinking water (author's transl)].

The incidence of caries in terms of the so-called DFS (= Decayed filled surfaces) index was ascertained for test persons aged from 6 to 15 years, in a community with a drinking water supply having a naturally increased fluoride content (Falkenberg/Oberpfalz, 1.8 ppm F') in comparison with test persons from a neighbouring community with a drinking water supply having a low-fluoride content (Fuchsmühl/Oberpfalz, 0.05 ppm F'). In 103 persons tested (corresponding to 7,577 dental surfaces surveyed) from Falkenberg, the DES index was 5.3, in 123 test persons (corresponding to 10,473 dental surfaces surveyed) from Fuchsmühl the DFS index was 12.4, which means that the naturally increased fluoride content of the drinking water caused caries to drop by 58 per cent viv-à-vis the reference group. No appreciable differences were found to exist in the eruption times of the permanent teeth in both groups of test persons, i. e. fluoride in drinking water does not appear to delay the eruption of teeth. The incidence of fluoride-induced enamel hypoplasia as determined by Kunz on the same test persons, resulted in a distinct increase of 74 per cent for the "fluoride group" vis-à-vis the reference group with a 33 per cent increase only.