Bone‐bonding ability of P2O5‐Free CaO · SiO2 glasses

Abstract

AbstractAn apatite‐ and wollastonite‐containing glass‐ceramic (A · W‐GC) has been reported to form a tight bond with living bone through an apatite layer formed on its surface. This layer is considered to be formed by dissolution of Ca2+ and HSiO3− ions from the glass‐ceramic into the surrounding body fluids. In order to confirm this proposed mechanism for the surface reaction of A · W‐GC, three kinds of glass in the systems CaOSiO2, CaOSiO2CaF2, and CaOSiO2P2O5 were implanted into the tibiae of rabbits for 3 or 8 weeks. Contact microradiography and SEM‐EPMA showed that all three kinds of glass formed a Ca, P‐rich layer in combination with a Si‐rich layer on their surfaces within 3 weeks and formed a direct bond with bone via these layers. The detaching test, performed 8 weeks after implantation, showed that the loads required to detach the implants from the bone were almost equal for the phosphorus‐free and the phosphorus‐containing glasses. It was concluded that even P2O5‐free CaO · SiO2 glass formed a Ca,P‐rich layer on its surface and bonded tightly with living bone. If glasses and glass‐ceramics release at least Ca2+ and HSiO3− ions, this would be sufficient for them to form the Ca,P‐rich layer on their surfaces in vivo, enabling them to bond directly with bone.