Comparison in Physical Properties and in Vivo Test of Synthetic Carbonate Apatite and Allogeneic Bone Graft Substitute
Objectives: Autologous bone graft have been the gold standard for bone augmentation. But invasion to the healthy site remain as a concern. There has been a demand for bone graft substitutes which has potential to be replaced with autogenous bone. Especially in the U.S., allogenic bone graft materials have been widely used in the field of dental bone regeneration. We have developed a novel bone graft substitutes “Cytrans Granules (Cyt)” consisting synthetic carbonate apatite, which is the main component of human bone. In this study, we have compared the composition, crystal structure of Cyt to freeze-dried bone allograft (FDBA) as an allogeneic bone. In addition, early bone regeneration ability was evaluated in animal study.
Methods: Cyt was used as test sample, FDBA was used as control. The composition and crystal structure were analyzed using Fourier transform infrared spectroscopy (FT-IR) and powder X-ray diffraction (XRD). Animal experiment was performed at Hamri Co., Ltd., which was approved by the Association for the Assessment and Accreditation of Laboratory Animal Care (AAALAC) International)of Hamri Co., Ltd.；Approval number-No. 15-H066. Bone defects were created at mandible bone of beagle dogs. Each sample was implanted in the bone defects (n = 3). After 4 weeks of implantation, the samples were carefully harvested from the mandibular bone. Subsequently, Villanueva Goldner stain was applied to all sections and observed using a microscope.
Results: XRD pattern showed that all samples have apatitic crystal structure. FT-IR spectrum showed that all samples contain carbonate group. In Villanueva Goldner staining in histological images at 4 weeks after implantation, new bone formations were observed at all samples. At the FDBA sample’s image, new bone formation was only in the lower portion of bone defect. On the other hands, larger amount of new bone was observed in the Cyt group, and new bone formation was observed even in the central and upper portions.
Conclusions: It was confirmed that Cyt and FDBA are containing carbonate group. Cyt had composition, crystal structure similar to those of FDBA. From the result of animal study, Cyt showed the same or better bone regeneration ability as FDBA. From these results, it was suggested that Cyt is a highly functional bone graft substitute that replaces bone.