Effect of magnesia on structure, degradability and in vitro bioactivity of CaO–MgO–P2O5–SiO2 system ceramics

CaO–MgO–P2O5–SiO2 system ceramics with various magnesia contents (0, 5, 10 and 20 mol%) were successfully prepared by sintering the sol–gel-derived powder compacts. The ceramic degradation was evaluated through the weight loss in the tris-(hydroxymethyl)-aminomethane and hydrochloric acid (Tris–HCl) buffer solution, and their ability to form apatite was determined by soaking in simulated body fluid (SBF). Results indicated that the ceramics structure was greatly influenced by magnesia contents. New crystal phases of Ca2MgSi2O7 and SiO2 were formed when magnesia was added and with an increase of magnesia concentration the phase of Ca2MgSi2O7 increased with a simultaneous decline of β-CaSiO3. In addition, studies showed that magnesia played an important role in affecting the degradability and apatite forming ability of CaO–MgO–P2O5–SiO2 system ceramics. It is observed that with increasing magnesia concentration, the ceramic degradability gradually decreased and the formation of apatite on samples was delayed.