EXPERIMENTAL STUDIES ON A NEW BIOACTIVE BONE-CEMENT - HYDROXYAPATITE COMPOSITE RESIN

We developed hydroxyapatite composite resin (CAP) as a new type of bio active bone cement. CAP is composed of 80% w/w hydroxyapatite granules (mean particle size: 2 mu m) and bis-phenol-A glycidyl methacrylate-b ased resin. The setting time is 5 min and the peak curing temperature during polymerization is 46 degrees C. In this study, the mechanical s trength of CAP and the biological behaviour of the CAP-bone interface were examined. The compressive strength of CAP was 260 MPa and this wa s about three times greater than that of commercial polymethylmethacry late (PMMA) bone cement. The tensile strength and fracture toughness o f CAP also exceeded those of PMMA cement. CAP was implanted into the f emoral condyles of rabbits. Two weeks later, new bone formation was al ready seen on the surface of the CAP implants. At 8 wk, bone was growi ng directly onto the surface of the CAP implants and no intervening fi brous tissue could be observed at the CAP-bone interface. These result s show that CAP is a promising material which possesses superior mecha nical strength and the biological property of achieving direct contact with bone.