Fluoride concentrations of the surface enamel of children living in an optimally fluoridated community.

The present study was undertaken in a community, where the tap water has been optimally fluoridated since 1959 (1.0-1.2 ppm). The material consisted of 92 children and adolescents including 30 sibling-couples. The mean age of the participants was 11.8 +/- 2.45 (SD) yr. 56 children had consumed fluoridated water all their life, the others only a part of the developmental period of their permanent dentition. Enamel biopsies were taken from 212 permanent teeth and 33 primary teeth by etching the tooth surface for 6 or 30 s. The etch depth was calculated from the mean of dissolved enamel calcium and phosporus. The fluoride concentration in the outermost enamel was almost similar in the teeth of the lifelong residents and the rest of the children. Towards the deeper layers the amount of fluoride decreases depending on its availability during the development of the enamel. There was no striking similarity neither in the fluoride concentration nor in the amount of dissolved enamel between the siblings when compared with the other children. The posteruptive incorporation of fluoride takes place only on the outermost surface of the enamel. The results suggest that in subsurface layers the fluoride exposure during tooth formation is the dominating determinant of enamel fluoride concentration.