An use of fluoride is one of the most effective method for caries prevention, however, the definite mechanism of caries prevention by fluoride has not yet been clarified. Recently the effect of fluoride in physicochemical process of dilution of
hydroxyapatite has been argued whether it is caused by firmly bound fluoride lie fluoroapatite or by fluoride ion adsorbed onto the surface or by the fluoride ion solution. So the purpose of this study is to evaluate the effect of fluoride in
soluble
state on the degree of enamel remineralization and the effect of fluoride contained in enamel like fluoridated hydroxyapatite and free fluoride ion diluted in solution on prevention for enamel demineralization.
Enamel powder from the bovne teeth wit constant particle size(diameter 106~150§) was used. The degree of remineralization was observed from recording the Ca2+ concentration changes in solution with Ca2+ electrode for 90 minutes during the
inducing
process of crystalinization by mechanically stirring under remineralization buffer solutions having four group of different NaF concentration (0, 10-5, 10E-4, 10E-3M) with pH 7.2 and containing 1.0mM CaCl2 and 7.5mM KH2PO4 And also, the amount of
fluoride incorporated to the crystal during the remineralization process with F- electrodes was measured. The amount of dilution of enamel by recording the output of Ca2+ into the solution with Ca2+ electrodes for 70 minutes during the
demineralization
process in the 0.1 M lactic acid buffered solution with four groups of different NaF concentration (0, 10E-5, 10E-4, 10E-3M) with pH 4.5 was observed. And previous remineralized enamel powder from four groups of different NaF concentrationw as
demineralized without the addition of fluoride in 0.1M lactic acid buffered solution with pH 4.5 and the output of Ca2+ with Ca2+ electrode was continouously recorded for 70 minutes. And results were 1) as the concentration of fluoride in the
solution
increased, the degree of remineralization of enamel powder increased, 2) as the concentration of fluoride in solution increased, the amount of demineralization of enamel powder decreased, 3) the small aount of fluoride bound to crystals as
fluoroapatite
during enamel remineralization did not affect the process of demineralization, 4) the fluoride diluted in solution slowly reacted in the rocess of remineralzation of enamel powder, and immediately in the process of demineralization.
From the above results, fluoride is more effective on enamel demineralization as the state of diluted in solution than as the state of fluoroapatite. So for the effective use of fluoride, to maitain low concentration of free fluoride ion in oral
fluid
by slow flouride releasing device is advisable.
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