Compositional and histological comparison of carbonate apatite fabricated by dissolution-precipitation reaction and Bio-Oss®

Carbonate apatite (CO(3)Ap) is an inorganic component of bone. This study aimed to compare the composition and tissue response to of CO(3)Ap (CO(3)Ap-DP) fabricated by the dissolution-precipitation reaction using calcite as a precursor and Bio-OssA (R), which is widely used in orthopedic and dental fields as a synthetic bone substitute. X-ray diffraction and Fourier transform infrared results showed that CO(3)Ap-DP and Bio-OssA (R) were both B-type carbonate apatite with low crystallinity. The average sizes of CO(3)Ap-DP and Bio-OssA (R) granules were 450 +/- 58 and 667 +/- 168 mu m, respectively, and their carbonate contents were 12.1 +/- 0.6 and 5.6 +/- 0.1 wt%, respectively. CO(3)Ap-DP had a larger amount of CO3 than Bio-OssA (R) but higher crystallinity than Bio-OssA (R). When a bone defect made at the femur of rabbits was reconstructed with CO(3)Ap-DP and Bio-OssA (R), CO(3)Ap-DP granules were partially replaced with bone, whereas Bio-OssA (R) remained at 8 weeks after implantation. CO(3)Ap-DP granules elicited a significantly larger amount of new bone formation at the cortical bone portion than Bio-OssA (R) at 4 weeks after the implantation. The results obtained in the present study demonstrated that CO(3)Ap-DP and Bio-OssA (R) showed different behavior even though they were both classified as CO(3)Ap. The CO3 content in CO(3)Ap played a more important role than the crystallinity of CO(3)Ap for replacement to bone and high osteoconductivity. [GRAPHICS] .