Bone augmentation using novel unidirectional porous hydroxyapatite with bone morphogenetic protein-2 on rat skull

Unidirectional porous hydroxyapatite (UDPHAp) is a material whose microstructure consists of cross- sectional oval pores with a pore diameter in the range of 100-300 m that penetrate through the material. UDPHAp has proven suitable for osteogenesis and angiogenesis. The present study was designed to evaluate the osteogenic effect of a newly developed UDPHAp as a carrier of recombinant human bone morphogenetic protein-2 (rhBMP-2) in a rat onlay graft model. UDPHAp was implanted beneath the calvarial periosteum of rats to simulate alveolar bone augmentation in a clinical condition. At 2 weeks after implantation, UDPHAp with rhBMP-2 resulted in active bone formation, and the augmented bone was connected directly with the original bone, whereas commercialized porous hydroxyapatite (PHAp) with rhBMP-2 showed little bone formation. These results suggest that UDPHAp in this model is suitable for onlay graft and is an effective biomaterial for the rhBMP-2 delivery system.