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 Æ (57.0 x)CaO Æ 35.4SiO2 Æ 7.2P2O5 Æ 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.
2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.