フッ化物溶液作用エナメル質における生成フルオロアパタイトのＸ線回折法による研究

The present study was made to examine the effects of two topical fluoride agents on the fluorapatite formation in enamel powder by X-ray diffractometry using the template technique. Fluoride topical application and fluoride mouth rinse were applied in vitro to enamel powder (200 mesh), and the findings were compared. Acidulated phosphate fluoride solution (F^-: 9000 ppm, pH 3.6) was used as the fluoride topical application (F.T.A.) and phosphoric acid-acidified NaF solution (F^-: 500 ppm, pH 5.0) was used as the fluoride mouth rinse (F.M.R.). X-ray diffractometry was performed with an automatic recording X-ray diffractometer. The reaction products were identified by comparison with ASTM indices. For the determination and identification of reaction products, templates were made of the (410) diffraction line profile of the reference substance after heating it at 1, 000°C for 5 hours. A part of the experimental samples were also heated. These templates were used to determine the amount of fluorapatite by comparison of alterations in the diffraction line profiles, and peak shifts in the a-axis of enamel apatite after heating. The determination of β-tricalcium phosphate produced by heating was carried out by X-ray diffractometry using the internal standard technique.<BR>The following results were obtained.<BR>The amount of fluorapatite formed in the enamel powder was estimated at about 20% for F.T.A., and about 35% for F.M.R.. In the experiments with F.T.A., a large amount of CaF₂ was produced, which was released with time by washing, after the formation of fluorapatite. A large amount of fluorapatite with high crystallinity was produced by the repeated treatment with F.M.R. solution.<BR>Hydroxyfluor-apatite and/or fluoridated hydroxyapatite was indicated in the line profile of fluoride treated enamel. Peak shift and decrease of the a-axis lattice parameter in F.M.R. also showed the formation of hydroxyfluonapatite. The amount of g-tricalcium phosphate produced by heating in enamel treated with F.M.R. solution decreased with time. These facts indicate a decrease in the amount of imperfect hydroxyapatite and the restoration of lattice imperfections in enamel apatite after the application of F. M. R..<BR>Thus, the repeated application of fluoride mouth rinse over a long period will produce hydroxy-fluor-apatite without decalcifying the enamel and thus will exert a favorable effect on enamel apatite.