Gene Expression and Microcomputed Tomography Analysis of Grafted Bone Using Deproteinized Bovine Bone and Freeze-Dried Human Bone

Purpose: Bio-Oss and demineralized freeze-dried bone allograft (DFDBA) are two commercial bone grafts that have been associated with clinical success for many years. However, there are few in vivo studies regarding their healing mechanism. The purpose of this study was to investigate the level of bone formation using microcomputed tomography (micro-CT) and gene expression in mouse calvaria at 1 and 3 months after bone grafting with deproteinized bovine bone and freeze-dried human bone, and compare them to natural bone healing. Materials and Methods: Thirty-six mice were divided into three groups (n = 6 per group) according to the type of bone graft used: group 1 (control)-an empty defect without bone graft; group 2- treatment with deproteinized bovine xenograft (Bio-Oss); group 3-treatment with DFDBA. The bone graft was inserted into two 3-mm calvarial defects created on both sides of the parietal bone. At 1 and 3 months, the mice were sacrificed and bone volume was evaluated using micro-CT and gene expression analysis using reverse transcription polymerase chain reaction (RT-PCR). Results: Micro-CT analysis demonstrated that the parietal bone of mice grafted with Bio-Oss had significantly greater bone volume than both the DFDBA and control groups at both 1 and 3 months. The expression of bone marker genes (Runx2, Osterix [Osx], alkaline phosphatase [ALP], osteopontin [OPN], and osteocalcin [OCN]) were significantly increased from 1 month in both Bio-Oss and DFDBA groups at 3 months. Runx2 and Osx had significantly higher expression in the Bio-Oss and DFDBA groups compared to the control group at 3 months. No statistically significant difference was observed among groups after 1 month. Conclusion: These results showed that both bone graft materials promoted bone regeneration. Bio-Oss demonstrated high osteoconductive properties. Keywords: Bio-Oss, calvarial defect, DFDBA, mice, micro-CT, real-time PCR