[Cross-sectional comparison of the median eruption time for permanent teeth in children from fluoride poor and optimally fluoridated areas].

Nearly 57000 children (aged from 4 years, 4 months to 15 years, 9 months) of Karl-Marx-Stadt (1.0 ppm F) and Plauen (0.2 ppm F) were examined to compare the mean eruption times of permanent teeth before and after 12 years of water fluoridation. Whereas a direct influence of internally administered fluorides is to be excluded, an indirect action on the premolars may be assumed with certainty. The delayed eruption of all premolars in children of the area with optimally fluoridated water was the only systematic effect which could be detected. This normalization is explained by a prolonged stay of the deciduous teeth in the dental arch which is due to a lesser caries prevalence.