[Wet synthesis and characterization of fluoride-substituted hydroxyapatite]

Hydroxyapatite and fluoride-substituted hydroxyapatite powders are synthesized by wet method, compacted into pellets and subjected to heat treatment at 300, 600, 900 degrees C respectively. Analysis of the fluoride-substituted hydroxyapatites and HA by FTIR spectroscopy indicated that with the increasing of sintering temperatures, the phase-pure fluoride-substituted hydroxyapatite and stoichiometric hydroxyapatite could be got. According to the X-ray diffraction analysis, the fluoride-substituted hydroxyapatite is less stable for decomposing into beta-Ca3(PO4)2 at the temperature of 900 degrees C. The in vitro bioactivity of the fluoride-substituted hydroxyapatites and hydroxyapatite heat treated at 900 degrees C was assessed by immersion testing in simulated body fluid (SBF). Both scanning electron microscopy (SEM) analysis and ionic solution changes (Ca2+) demonstrated that the low fluoride content apatite could induce a surface bonelike apatite layer formation.