Comparative study of biphasic calcium phosphate ceramics impregnated with rhBMP-2 as bone substitutes

We investigated pellet-shaped implants prepared from biphasic calcium phosp hate (BCP) ceramics with five different ratios of hydroxyapatite (HAP) to b eta -tricalcium phosphate (beta -TCP) to evaluate these ceramics as bone su bstitutes. BCP ceramics impregnated with different doses of recombinant hum an bone morphogenetic protein 2 (rhBMP-2) (1, 5, and 10 mug) were used for experimental purposes and ceramics without rhBMP-2 were used for control. T he pellets were implanted under the pericranium in adult Wistar male rats a nd were harvested 8 weeks after implantation. The retrieved pellets were th en examined radiologically, histologically, and histomorphometrically. The results revealed that the pellets treated with rhBMP-2 exhibited new bone a nd bone marrow, whereas control pellets produced fibrous connective tissues . The formation of new bone induced by rhBMP-2 was dose dependent. The exte nt of bone and bone marrow formation and the degree of resorption of the ce ramic particles were significantly higher in the pellets composed of 25% HA P-75% TCP. In this study, bioresorption of the ceramic produced favorable c onditions for rhBMP-2-induced bone formation. (C) 2000 John Wiley & Sons, I nc.