The Pre‐and Posteruptive Effects of Fluoride in the Caries Decline

Abstract

The widespread availability of fluoride from many sources is accepted as a major reason for the caries decline among children in developed countries. There is still controversy, however, about its principal mode of action. This article reviews the evidence on fluoride's preeruptive and posteruptive effects, and suggests reasons for its continuing role in the caries decline. Early fluoridation studies accepted that fluoride acted preruptively through incorporation into developing enamel; but further research could not explain why fluoride levels were not clearly higher in enamel exposed to fluoride, nor why there were no clear correlations between caries experience and enamel fluoride concentration. Instead, considerable evidence suggests that fluoride acts mainly, though not entirely, through posteruptive remineralization of demineralized enamel. Caries experience has declined in nonfluoridated as well as in fluoridated areas, though DMF scores are still consistently lower in fluoridated areas. Posteruptive remineralization effects are seen from fluoridated drinking water as well as with fluoride from other sources. The continuing caries decline, beyond the level suggested by early fluoridation field trials, can be attributed either to more efficient remineralization or to long-term, intraoral ecological change, or to both.

Enamel Fluoride Concentrations in Unerupted Third Molars and the Influence of Fluoridated Water on Caries Scores

“…It has been proposed that higher levels of fluoride in sur face enamel, acquired pre-eruptively, become available when subsurface enamel demineralization occurs, and that these higher fluoride levels in the enamel fluid o f the in cipient lesion enhance the remineralization process [Beltran and Burt, 1988;Thylstrup, 1990;Melberg, 1992;Tanaka et al, 1993], However, the precise relationship and mecha nisms involved have not been defined. It should be noted that the relationship to caries scores was inverse but similar.…”

Opinion of the Scientific Panel on Dietetic Products, Nutrition and Allergies (NDA) on a request from the Commission related to the Tolerable Upper Intake Level of Fluoride

“…The prevalence of dental caries in a population was not inversely related to the concentration of fluoride in enamel (Clarkson et al, 1996), which apart from the outmost surface is accumulated through pre-eruptive enamel development (Richards et al, 1992;Weatherall and Robinson, 1988). Fluoridated enamel is less acid soluble (Beltran and Burt, 1988). It was also demonstrated that the positive effect on reduction of caries in both deciduous and permanent teeth was more marked the earlier children were exposed to fluoridated water or fluoride supplements (Groeneveld et al, 1990;Stephen et al, 1987).…”

Water fluoridation: It really is this simple

“…Although fluoride is not essential for tooth development, enamel containing fluoroapatite is more resistant to acids (dissolves at a lower pH) than enamel containing only hydroxyapatite. [73,209] However, studies of fluoride supplementation in pregnancy have not shown them to be effective, and because of the possibility of increased risk of fluorosis, fluoride supplements are no longer recommended.…”