Enamel fluoride and caries in Icelandic children and a comparison of enamel fluoride in Swedish and Icelandic children.

The fluoride content in surface enamel and its relationship to caries experience was studied in a group of Icelandic schoolchildren living in a low-fluoride area. Fluoride content was assessed by means of in vivo enamel biopsies sampled from 248 subjects aged 11 and 12 years. Dental examinations were performed in conjunction with the biopsy sampling and by the same examiner 1 year later. The prevalence and incidence of initial (DSI) and manifest (DFS) caries lesions were recorded separately. A median fluoride concentration of 610 ppm at a median biopsy depth of 4.2 microns was observed. A significant positive correlation was found between DSI and enamel fluoride content in girls and all older children. Additionally, surface enamel fluoride was measured in 72 Swedish children from a low-fluoride area but exposed to regular topical fluoride treatments. The difference in mean fluoride concentrations between the Icelandic and Swedish study populations was highly significant. From the measured fluoride concentrations the enamel fluoride profiles for both study populations were constructed. The differences in fluoride content were most pronounced in the outermost layer, apparently reflecting the higher exposure to and acquisition of topical fluoride in the Swedish children.