Production of Hydroxyapatite/Bioactive Glass Biomedical Composites by the Hot-Pressing Technique

Biomedical composites of hydroxyapatite (HA) and bioactive glass (BG) have been difficult to obtain as a dense body without the undesirable occurrence of thermal reactions and phase degradation. Herein, HA–BG dense composites were produced by the hot-pressing technique. A range of HA–BG powder mixtures (30–50 wt% BG) was fully densified by hot pressing at temperatures as low as ～700°–800°C. On the other hand, the HA–BG composites could not be densified by pressureless sintering because their composition was degraded due to a severe thermal reaction. The hot-pressed composites had significantly improved flexural strengths (～60 MPa) as compared with those subjected to pressureless sintering (～30 MPa) or the pure HA control (～40 MPa). The hot-pressed HA–BG composites showed significantly enhanced bioactivity in a simulated body fluid, as well as osteoblast cell activity with respect to the pure HA, confirming their excellent in vitro biocompatibility.