title: Transmission electron microscopic observation of heterogeneous fluoridated hydroxyapatites.
abstract: 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.
authors.affiliation: Department of Ultrastructural Science, Tokyo Dental College, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Tohda
authors.forename: M
authors.initials: M
authors.lastname: Okazaki
authors.forename: T
authors.initials: T
authors.lastname: Yanagisawa
authors.forename: J
authors.initials: J
authors.lastname: Takahashi
mesh_terms: D006882:Hydroxyapatites / Q000737:chemistry*; D017665:Hydroxyl Radical; D008854:Microscopy, Electron; D012015:Reference Standards; D013057:Spectrum Analysis; D014961:X-Ray Diffraction
chemical_list: D006882:Hydroxyapatites; D017665:Hydroxyl Radical; C028869:fluor-hydroxylapatite