Histopathological studies of implantation of hydroxyapatite in the rat jaw bone

Abstract

This study was performed to examine the osteogenesis-inducing capacity of hydroxyapatite (HAP) with non-sintering or sintering condition. Three HAPs, Undrying slurry HAP, drying HAP at 200°C and sintering HAP at 800°C, were used. Each HAP was filled into an osseous cavity prepared in the rat mandible. Observation periods were 3 days, 1, 3, 8 and 12 weeks after the filling of each HAP into the osseous cavity.
Histologic sections showed osteogenesis around each HAP particle. Each HAP particle was embedded in the new bone unlike tricalcium phosphate. Also, it was difficult to determine the difference of osteogenesis between each HAP.
In early periods of HAP filling, macrophages or multinuclear giant cells phagocytized HAP micro-particles. Thus, this study indicated that HAP had osteogenesis-inducing capacity which was not affected by sintering conditions in the synthesis process of HAP. We also proposed that the particle size of HAP had to be larger than the size of the particle phagocytized by phagocytic cells for the inducer of osteogenesis.