Experimental studies on a new bioactive bone cement: hydroxyapatite composite resin.

We developed hydroxyapatite composite resin (CAP) as a new type of bioactive bone cement. CAP is composed of 80% w/w hydroxyapatite granules (mean particle size: 2 microns) and bis-phenol-A glycidyl methacrylate-based resin. The setting time is 5 min and the peak curing temperature during polymerization is 46 degrees C. In this study, the mechanical strength of CAP and the biological behaviour of the CAP-bone interface were examined. The compressive strength of CAP was 260 MPa and this was about three times greater than that of commercial polymethylmethacrylate (PMMA) bone cement. The tensile strength and fracture toughness of CAP also exceeded those of PMMA cement. CAP was implanted into the femoral condyles of rabbits. Two weeks later, new bone formation was already seen on the surface of the CAP implants. At 8 wk, bone was growing directly onto the surface of the CAP implants and no intervening fibrous tissue could be observed at the CAP-bone interface. These results show that CAP is a promising material which possesses superior mechanical strength and the biological property of achieving direct contact with bone.