BIOACTIVE GLASS-CERAMIC - FORMATION, CHARACTERIZATION AND BIOACTIVITY

A new bioactive glass-ceramic with the nominal composition CaO (54.5), MgO (6.0), SiO2 (32.8), P2O5 (6.1) and CaF2 (0.6) (in wt.%) has been developed. Crystalline phases, termed akermanite, wollastonite and apatite, were found to precipitate simultaneously at temperatures between 930 and 1150-degrees-C. No cracks appear in the glass-ceramic after crystallization. This new type of glass-ceramic demonstrates a flexural strength of 233 MPa and a fracture toughness of 2.95 MPa m1/2, which are higher than those of dense hydroxyapatite and other well-known bioactive materials. The glass-ceramic exhibits a high bioactivity in vitro. The occurrence and recombination of surface cracks in the material can be observed when it is immersed in a simulated bodily fluid (SBF) for sufficient periods, and this can be explained in terms of a self-healing mechanism. The mechanism of apatite formation onto the surface of the glass-ceramic is discussed.