Fluoride contents of surface enamel in high‐ and low‐fluoride areas studied with a sensitive physical method

Fluoride content was measured with a sensitive physical method in the enamel of the four smooth surfaces of 12 primary and 12 permanent teeth from areas with drinking water of high‐ and low‐fluoride content. In the high‐fluoride area (1.9 parts/10 6 in drinking water) the average fluoride content of the surface enamel was 1,826 parts/10 6 and in the low‐fluoride area (0.05 parts/10 6 . Permanent teeth contained about 20% more fluoride than primary teeth. In two children in the low‐fluoride area the fluoride content of the enamel was exceptionally high in the vestibular surface, presumably owing to local application of fluorides.