Fluoride analysis of apatite crystals with a central planar OCP inclusion: concerning the role of F- ions on apatite/OCP/apatite structure formation.
To study the roles of F- ions in the formation of apatite crystals embedding octacalcium phosphate (OCP) lamella in the center of apatite (Ap), a range of the Ap/OCP/Ap lamellar-mixed crystals were synthesized under various concentrations of fluoride ion (F-) from 0. 1-1.0 ppm at pH 6.5 and 37 degrees C. The products were analyzed for the F- incorporation, F- distribution, and the amount of OCP and Ap by chemical analysis, X-ray diffraction (XRD), electron probe microanalysis (EPMA), and nuclear magnetic resonance (NMR) techniques. The F- content and the amount of apatite in the crystalline product increased with an increase in the F- concentration in solution, whereas the amount of OCP and the yield of total product decreased. EPMA indicated that F- ions are distributed in the crystals almost homogeneously. The combined analysis suggested that a low-substituted fluoridated hydroxyapatite (FHAp) grew on a small amount of F--containing OCP or on a surface-reaction layer of OCP, which has accumulated a small amount of F-. The roles of F- ions were hypothesized as the reduction of the growth rate and/or the critical thickness in the a*-axis direction of OCP, the enhancement of hydrolysis of OCP, and the activation of the growth of FHAp, resulting in thinner OCP lamella and thicker apatite lamella in the a*-axis direction with an increase in F- concentration.
Iijima
M
M
Department of Dental Materials and Technology, School of Dentistry, Asahi University, 1851-1 Hozumi, Hozumi-cho, Motosu-gun, 501-02 Gifu, Japan.
Nelson
D G
DG
Pan
Y
Y
Kreinbrink
A T
AT
Adachi
M
M
Goto
T
T
Moriwaki
Y
Y
D001031:Apatites / Q000737:chemistry*; D002130:Calcium Phosphates / Q000737:chemistry*; D003460:Crystallization; D005459:Fluorides / Q000737:chemistry*
D001031:Apatites; D002130:Calcium Phosphates; C022045:octacalcium phosphate; D005459:Fluorides