Magnesia-doped HA/β-TCP ceramics and evaluation of their biocompatibility

The sintering behavior, mechanical properties and biocompatibility of magnesia (MgO)-doped HA/TCP biphasic ceramics were studied. Pure HA/TCP ceramics showed poor sinterability due to the phase transformation of β- to α-TCP. MgO-doped HA/TCP ceramics showed high density without any phase transformation of β-TCP up to 1300°C, for MgO dopants incorporated into the β-TCP preferably and increased thermal stability of β-TCP. However, the addition of MgO higher than a critical content, suppressed grain growth of HA/TCP ceramics and lowered sinterability. The optimum amount of MgO doping was 1 wt%, which lead 99% relative density and higher mechanical properties than HA or β-TCP ceramics. From in vitro test and in vivo test, 1 wt% MgO-doped HA/TCP ceramics showed a good biocompatibility without cytotoxicity. After implantation under the muscle of rabbits, β-TCP phase was dissolved from the surface and a biological apatite covered the surface. These results proved that MgO addition increased drastically the sintering and mechanical properties of HA/β-TCP ceramics without altering the biological safety and biocompatibility of the original composite.