In vivo fluorine uptake in human enamel following treatment with a varnish containing sodium fluoride

Abstract

Fluorine concentrations were determined in three successive enamel layers (approximately 10, 10 and 25 microns in width) of 21 pairs of contralateral teeth, by etching with perchloric acid. The F-concentrations in five untreated pairs of teeth were measured and compared (Group I). A decrease in the F-content from about 1100 ppm in the outer layer to 400 ppm at 40 microns from the enamel surface was found. The differences in F-concentrations between contralateral teeth extracted from the same mouth were small and not statistically significant. In five teeth (Group II) th F-uptake was determined one day after a single topical application of a varnish which contained 5% NaF (Duraphat), and compared with the corresponding control contralateral teeth. A significantly increased concentration of F was observed in all analysed enamel layers of the treated teeth: 3270 +/- 128 (1048 +/- 145), 1520 +/- 97 (596 +/- 61), 567 +/- 52 (296 +/- 14) ppm. Values within brackets denote concentrations in control teeth. In another five teeth (Group III) the fluorine concentration was determined one week after a single application of Duraphat. A significant increase in the F-concentrations in three enamel layers of the test-teeth was found as compared to the control-teeth: 1732 +/- 156 (884 +/- 101), 904 +/- 82 (464 +/- 79) and 524 +/- 88 (296 +/- 24) ppm F. The test-teeth in this group contained less fluorine in the outermost enamel than did the teeth in group II. The difference was significant for the outer two layers. Approximately the same concentration of fluorine was found in test-teeth analysed five weeks after treatment as observed at one week, using same varnish (Group IV). The respective values were: 1795 +/- 410 (907 +/- 216), 749 +/- 135 (369 +/- 90), 382 +/- 88 (166 +/- 40) ppm. The F-increase was significant for all enamel layers analysed.