Abstract
The mode of the release of uptaken fluoride in enamel was examined in vivo at a depth of ca. 0.5-50 μm in specimens of human exfoliated deciduous teeth after APF application (0.9% F, pH 3.6) at different times. Rapid decrease of uptaken fluoride occurred in vivo within 6 to 24 hours, after which the remaining fluoride (2, 000-3, 500 ppm) was retained one month after APF application at a depth of 0.5-2.4 μm from the surface enamel. The innermost uptaken fluoride levels (at ca. 20-50 μm) of APF treated enamels, however, were not statistically higher than those of untreated enamels. Prolonging the application time greatly increases the fluoride penetration to the surface enamel. A 1 min application reaches the first layer (1.5μm), a 2 min application, the second layer (4.2μm), a 3 min application the third layer (10.6 μm), and a 5 min application the third layer (12.4 μm). Fluoride treatment markedly reduced the enamel solubility by about 50 % when compared with the control groups in determining of dissolved calcium levels obtained from the outermost enamel layers.
