It is shown in this study how bioactive glass-ceramic A-W with a high mechanical strength and bioactive surface-modified Ti metal with a high fracture toughness was derived from Bioglass®. Glass-ceramic A-W precipitating apatite and wollastonite was obtained by crystallization of a glass of a modified composition of Bioglass®. The resultant product showed a higher mechanical strength than human cortical bone, as well as bone-bonding ability. It was clinically used for various kinds of bone substitute such as artificial vertebrae and iliac crest. However, its fracture toughness is not so high as that of human cortical bone. By examining bone-bonding mechanism of Bioglass® and glass-ceramic A-W, it was found that a material capable of forming bonelike apatite on its surface in the living body bonds to living bone through the apatite layer. The apatite formation on a material in the living body can be evaluated even in a simulated body fluid in-vitro. On the basis of these findings, a Ti metal with high fracture toughness was conferred bone-bonding ability by surface modification with simple chemical and heat treatments. The resultant products are in clinical use for an artificial hip joint and spinal fusion devices.
