フッ化チタン化合物によるエナメル質表層のｇｌａｚｅ形成について

Abstract

The purpose of this study was to examine the glaze-like substance which formed on enamel surface treated with titanium fluoride compounds.Specimens of intact enamel and powdered enamel were treated with solutions of (NH4) 2TiF6, TiCl3, APF, NH4F, or TiCl3 followed by treatment with APF solution and 48 hour washing with 1M KOH solution. Fluoride concentration of each solution was 0.9%, and pH was 3.4, except for TiCl3 (4000ppmTi, pH 1.0). Intact enamel was observed by scanning electron microscopy (SEM), electron microprobe analysis (EPMA), and microbeam X-ray diffractometry. In the experiments with powdered enamel, the fluoride uptake and retention in enamel were studied by chemical analysis, and X-ray diffraction analysis was performed.SEM images showed that the surfaces treated with (NH4) 2TiF6 solution had a tenacious coating which remained after washing. However, SEM image of cross sections did not show the existence of a glaze layer and only enamel apatite was detected by microbean X-ray diffractometry. TiCl3 treatment and TiCl3 pretreatment followed by APF treatment resulted in enamel etching, and reaction products were deposited on the enamel surface which were totally removed by washing. No glaze-like substance was detected. APF and NH4F treatments formed a large amount of CaF2, which was totally removed by washing. EPMA showed significant retention of fluoride and titanium at the depth of 10μm in (NH4) 2TiF6-treated enamel surface. On the TiCl3-APF treated enamel surface, a titanium and fluoride-rich layer was observed, which was totally removed by washing. However permanently bound fluoride and titanium retained in the surface. This fact suggests the possibility of glaze-like substance formation.In the chemical analysis of enamel powder, (NH4) 2TiF6-treated enamel showed lower fluoride uptake, but considerable higher retention of fluoride after washing, and higher fluoride uptake was found in the other fluoride-treated enamel. Most of these fluorides was released by washing.X-ray diffraction analysis showed that only enamel apatite was detected in (NH4) 2TiF6-treated enamel, and a large amount of CaF2 was formed in the other fluoride-treated enamel.I concluded that the glaze formation peculiar to titanium fluoride compounds were caused by coreaction of titanium and fluoride, and not by titanium reaction alone. Titanium forms an organometalic bond with the enamel protein and fluoride called ‘glaze’.