Background: In order to evaluate bone induction and repair in cranial bone defects by the use of combination of Octacalcium Phosphate/Bone Matrix Gelatin (OCP/BMG), this study was conducted.

Materials and Methods: We used 40 young male Sprague dawley rats (5-6 weeks age). A full thickness standardized trephine defect, 5mm in diameter, was made in the rat parietal bone and OCP combined with BMG was implanted into the defect. No OCP/BMG particles were implanted in control group that was otherwise treated identically. On the 5th, 7th, 14th, and 21st days after implantation, the rats were killed and bone samples collected. After processing the tissues by routine histological procedures, 5mm thick sections of bone were cut and stained with Haematoxyline and Eosin (H& E) and alcian blue and examined by light microscope.

Results: On the 5th day after implantation, inflammatory cells were seen around the implanted materials, especially around the OCP particles. A few clusters of cartilage cells were observed between the BMG particles in the central position of defects on the 7th day after implantation. On the 14th day after implantation, osteogenesis was seen at the margins of the defects. In addition to bone formation from the margins toward the center, interstitial growth of new bone tissue was seen around the implanted materials. By the end of 21st day, almost all of the OCP/BMG particles were absorbed and bone trabeculae, bone marrow cavities and bone marrow tissues were seen. In the control group, at the end of 21th day, a few areas of new bone were seen near to the defect margins and host bone, but much less than in the experimental group.

Conclusion: Therefore, implants of OCP/BMG appear to stimulate new bone growth in bone defects and these biomaterials could be used in the repair of cranial bone defects and injuries in clinical situations.