Transmission electron microscopic observation of heterogeneous fluoridated hydroxyapatites.
Two different types of heterogeneous fluoridated hydroxyapatites previously synthesized at 80 degrees C and pH 7.4, which might be composed of hydroxyapatite covered with fluorapatite (H-FAp) and fluorapatite covered with hydroxyapatite (F-HAp), were observed by high-resolution transmission electron microscopy. The transverse-sectional shapes of both apatites were clearly hexagonal. This confirmed that both apatites were highly crystallized. However, their shapes differed slightly from each other in detail:H-FAp was more slender and F-HAp was typically hexagonal, probably reflecting the shapes of the original core apatites, hydroxyapatite and fluorapatite. The portions thought to be synthesized with fluoride-free solution showed clear electron beam damage. The expanded lattice image observed at the edge of the F-HAp crystal coincided approximately with the a-axis dimension of 0.9443 nm obtained from the X-ray diffraction data of synthetic hydroxyapatite. After incubation in 0.5 mol l-1 acetate buffer solution (37 degrees C, pH 4.0) for one month, the fluorapatite-covered H-FAp maintained its sharp corners, while the hydroxyapatite-covered F-HAp showed rounded corners.
Tohda
H
H
Department of Ultrastructural Science, Tokyo Dental College, Japan.
Okazaki
M
M
Yanagisawa
T
T
Takahashi
J
J
D006882:Hydroxyapatites / Q000737:chemistry*; D017665:Hydroxyl Radical; D008854:Microscopy, Electron; D012015:Reference Standards; D013057:Spectrum Analysis; D014961:X-Ray Diffraction
D006882:Hydroxyapatites; D017665:Hydroxyl Radical; C028869:fluor-hydroxylapatite