Enamel biopsies taken from schoolchildren in a community where exposure to lead was a health hazard were analyzed for lead and fluoride. The children with high enamel lead had significantly higher caries scores than the children with low enamel lead, in spite of the fact that the high lead group also was higher in enamel fluoride. There was no increase in enamel lead with age. The lead in saliva was only a fraction of that in blood. Infants with lead poisoning showed higher saliva lead than a normal infant. The use of the lead in enamel biopsies and in saliva for measuring exposure to lead is discussed.
A method for in vivo measurements of the permeability of surface enamel was applied to the central maxillary incisor of two groups of children ranging in age from 7 to 9 and 13 to 14 years, respectively. The method involved exposure of a standard area of the surface enamel to 2 M KI, removal of the iodide present on the surface, and determination of back diffusion of the imbibed iodide. The mean ( ± SE) of recovered iodide, expressed in mole equivalents × 1010, was 34.0 (5.9) for the younger group (n = 27) and 4.1 (1.3) for the older group (n = 32). The difference was statistically significant (p < 0.01). It is concluded that posteruptive maturation of enamel involves a decrease in permeability to iodide. The drinking water was fluoridated 4 years before the study was undertaken and possible effects of the waterborne fluoride on the findings are discussed.
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