Osteoconductive effects of 3 heat-treated hydroxyapatites in rabbit calvarial defects

Purpose: This study aimed to detect the osteoconductive ability of 3 bovine hydroxyapatites (HAs) that were sintered at 800 degrees C (RA800), 1,200 degrees C (HA1200), and 1,350 degrees C (RA1350), according to new bone formation. Material and Methods: Two bicortical skull defects were prepared in 10 New Zealand white rabbits. Four rabbits were used as controls; in each, I defect was filled with autogenous bone chips and the contralateral defect was left empty for the critical size defect (CSD). The other 6 rabbits had a total of 12 defects, 4 each randomly filled with HA 800, HA1200, or HA1350. The animals were sacrificed at 8 weeks. New bone formation was assessed by radiographic densitometry and histomorphometric analysis. Results: The mean optical density (OD) of the CSD group (0.092 +/- 0.006) was less than that of the autogenous bone chip (0.102 +/- 0.002), HA1200 (0.108 +/- 0.005), and RA 1350 (0.102 +/- 0.003) groups. The mean OD of the RA 1200 group was significantly different from that of the HA 800 group (0.094 +/- 0.003). The histomorphometric analysis demonstrated that the autogenous bone chip group (34.89 +/- 4.61) was significantly different from the CSD (12.16 +/- 6.97), HA 800 (18-32 +/- 7.33), and RA1350 (13.99 +/- 3.94) groups, but not the HA1200 group (24-83 +/- 12.12). Conclusions: The findings demonstrate that heat-treated bovine HA enhances bone formation, and HA 1200 tends to provide greater bone formation than the other 2 HAs. (c) 2007 American Association of Oral and Maxillofacial Surgeons.