Fabrication of Titanium/Fluorapatite Composites and In Vitro Behavior in Simulated Body Fluid

Titanium/fluorapatite (Ti/FA) composites with various FA additions were fabricated by powder metallurgy. The decomposition of FA during sintering was accelerated by the presence of Ti. The main reaction products of FA and Ti were identified as CaO, Ti phosphides, and CaTiO₃. The addition of FA significantly inhibited the densification of Ti. The in vitro bioactivity of the composites was evaluated in a simulated body fluid (SBF). After immersion into the SBF, all the Ti/FA composites induced nucleation and growth of bone-like carbonated apatite on the surface. Co-precipitation of CaCO₃ and Mg(OH)₂ was also detected on the surface of the composite with high FA addition at an early stage of immersion. Furthermore, the release of fluorine ions from the composite was confirmed, which could promote bone regeneration and retard the formation of caries in the biological environment. The in vitro behavior was attributed to multiple factors, including the surface conditions and the constituents of the composite. The results demonstrated that the Ti/FA composites were bioactive in nature even with a low FA addition and they could introduce the benefit of fluorine ions in the service.