Fluoride uptake from a composite restorative by enamel.
The purpose of the study was to determine the in vitro uptake of fluoride by enamel adjacent to a fluoride-releasing composite restorative material containing 11.2 mg/g of fluoride. Blocks of human enamel were placed close to cured discs of the composite in synthetic saliva for periods of up to 24 hours. The fluoride content of successive acid-etch biopsy layers of the enamel blocks was determined by specific ion-electrode analysis, and atomic absorption analysis for calcium was used to determine the layer thickness. After 24 hours, a fluoride content of 5400 ppm was found for the outermost 10-micron layer of enamel. Based on the in vitro demonstration of appreciable fluoride uptake by adjacent enamel, the fluoride-releasing composite gives promise of having anticariogenic properties in vivo.