Bioactivity of CaO·SiO₂ glasses added with various ions

Abstract

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.