Surface enamel fluoride concentrations of different types of human teeth in a high- and near-optimal-fluoride area.

The surface enamel (approximately 4 micron) fluoride concentrations of different tooth types (11, 21, 22, 23, 24) were determined in 12-13-year-old children who were life-long residents in a naturally high (3.70 ppm) and in a near optimal (0.62 ppm) fluoride area. Enamel biopsies were taken by means of an acid-etch procedure, and the fluoride levels were measured with an adapted fluoride-ion-selective electrode. The enamel fluoride concentrations were related to the fluoride levels of the drinking water, and it appeared that the enamel fluoride concentrations of the different tooth types (except for the pre-molars) were associated with the length of the pre-eruptive period. In general, for both areas, the mean enamel fluoride concentrations increased from the central incisor to the lateral incisor and were found to be the highest in the canine, while the mean fluoride content of the first pre-molar nearly equaled that of the central incisor. No statistically significant differences (p greater than 0.05) were found between the enamel fluoride concentrations of the different tooth types or the etching depths, from different sexes.