Implantation of octacalcium phosphate nucleates isolated bone formation in rat skull defects.

OBJECTIVE

Our previous radiographic examinations have indicated that the synthetic octacalcium phosphate (OCP) may provide the core for nucleating multiple osteogenic sites in the experimentally created cranial defect.

DESIGN

The present study was designed to confirm the possibility that the implanted OCP causes the osteoinduction as well as the osteoconduction in the rat cranial defect.

MATERIALS AND METHODS

Standardized defects were created in male Wistar rat calvaria, and the OCP granules were implanted into the defect. The sham operated rats were processed in the same way except that nothing was implanted. The rats were fixed at 4 weeks after implantation of OCP or the sham operation. We examined bone formed on the implanted OCP, analyzing serial sections histologically combined with immunohistochemistry for the bone specific protein, osteocalcin.

RESULTS

In the defects treated with OCP, the radiopacity was scattered throughout the defect besides being observed along the defect margin of the parietal bone. Examination of the serial sections showed that some of new bones on the implanted OCP were formed away from the defect margin of the parietal bone with regard to both histological identification and specific molecular marker.

CONCLUSIONS

The present study suggested that the implanted OCP can serve as a core for initiating bone formation and cause the osteoinduction as well as the osteoconduction in the defect.