Effect of ZnO addition on bioactive CaO–SiO2–P2O5–CaF2 glass–ceramics containing apatite and wollastonite

Some ceramics show bone-bonding ability, i.e. bioactivity. Apatite formation on ceramics is an essential condition to bring about direct bonding to living bone when implanted into bony defects. A controlled surface reaction of the ceramic is an important factor governing the bioactivity and biodegradation of the implanted ceramic. Among bioactive ceramics, glass–ceramic A–W containing apatite and wollastonite shows high bioactivity, as well as high mechanical strength. In this study, glass–ceramics containing zinc oxide were prepared by modification of the composition of the glass–ceramic A–W. Zinc oxide was selected to control the reactivity of the glass–ceramics since zinc is a trace element that shows stimulatory effects on bone formation. Glass–ceramics were prepared by heat treatment of glasses with the general composition: xZnO · (57.0 − x)CaO · 35.4SiO2 · 7.2P2O5 · 0.4CaF2 (where x = 0–14.2 mol.%). Addition of ZnO increased the chemical durability of the glass–ceramics, resulting in a decrease in the rate of apatite formation in a simulated body fluid. On the other hand, the release of zinc from the glass–ceramics increased with increasing ZnO content. Addition of ZnO may provide bioactive CaO–SiO2–P2O5–CaF2 glass–ceramics with the capacity for appropriate biodegradation, as well as enhancement of bone formation.