Bioactivity of CaO·SiO2 glasses added with various ions

The purpose of this investigation was to study the fundamental compositional dependence of bioactivity for bioactive glasses by adding a third component such as Na2O, B2O3, Al2O3, Fe2O3, P2O5 or F− to binary calcium silicate glass. Rectangular specimens of these six kinds of calcium silicate glasses containing each 3 wt ratio third component were implanted into the tibias of mature rabbits for 8 or 25 weeks. Contact microradiograms and SEM-EPMA showed that all glasses, except for Fe2O3-containing glass, formed a Ca, P-rich layer in combination with a Si-rich layer on their surfaces within 8 weeks. The other four kinds of glass except that containing Al2O3 became attached to bone through these layers within 8 weeks, and even Al2O3-containing glass became attached to bone by 25 weeks. Fe2O3-containing glass did not form these layers, nor did it attach to bone even at 25 weeks. A detachment test, performed 8 weeks after implantation, showed that only glasses containing B2O3, P2O5 and F− bonded tightly with bone. Glass containing B2O3 maintained a tight bond at 25 weeks, but the other two kinds of glass showed decreased loads at 25 weeks.