Abstract
In this study, synthetic hydroxyapatite granules sintered at 1,250℃ were coated with synthetic hydroxyapatite dried at 200℃(they were designated as LHAP-coated HAP) to develop the new synthetic hydroxyapatite consisting of synthetic hydroxyapatite produced at different sintering temperatures. By scanning electron microscopy, LHAP-coated HAP consisted of two layers; one was the outer coated layer of synthetic hydroxyapatite dried at 200℃,about 4.0～6.0 μm thick, and the other was the inner layer of synthetic hydroxyapatite granules sintered at 1,250℃. Then, granules of LHAP-coated HAP, 0.3～0.5 mm in diameter, were implanted in Wistar rat mandibles to observe, using the light microscopy and microradiograms, the behavior of newly formed bone. One week after intraosseous implantation, few inflammatory cells were found to have infiltrated around the granules of LHAP-coated HAP, and the active formation of osteoid tissue and calus surrounded by many osteoblasts were found between them. Mature lamellar bone filled the space between them, and as bound directly to them 4 to 8 weeks after intraosseous implantation. On microradiograms, the interface between newly formed bone and LHAP-coated HAP was unclear. These results reveal that LHAP-coated HAP had high activity of osteoconduction, and connected with the newly formed bone. Therefore, it is concluded that LHAP-coated HAP is a very useful biomaterial for bone defects.
