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°C (HA800), 1,200°C (HA1200), and 1,350°C (HA1350), 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, 1 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 HA 1350 (0.102 ± 0.003) groups. The mean OD of the HA 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 HA1350 (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.