Abstract Objective: To evaluate the effect of collagen membrane (Bio- Gide®) coverage on the healing and integration of autogenous onlay mandibular bone graft. Methods: Each of the twelve adult sheep used in the study received two iliac corticocancellous onlay bone grafts on the lateral surface of the mandible. On one side (experiment), the block graft was placed in direct contact with the recipient bed and fixed with micro-screws, and the entire graft covered with collagen membrane (Bio-Gide®). On the other side (control), the bone graft was placed without collagen membrane coverage. The animals were euthanised at 4, 8, 12 or 16 weeks after surgery and the findings were analyzed by routine microscopy (Haematoxylin & eosin, and Tartrate resistant acid phosphatase (TRAP) stains) and immunohistochemistry for proliferation and apoptotic markers (Ki67 and Caspase-3). Results: After 8 weeks, grafts were fully incorporated in both the experiment and control groups. Pronounced resorption was observed in the control group and in the experimental group with membrane displacement. Minimal loss of graft volume was seen in the experimental group without membrane displacement. Osteoclasts expression peaked at 4 weeks in the control group, and at 8 weeks in the experimental group. Osteoblasts expressed moderate level of Ki67 at 8 weeks, and strongly expressed Caspase-3 at 16 weeks in both groups. Conclusions: The volume of onlay bone graft for mandibular augmentation can be maintained by covering the graft with collagen membrane, provided the membrane remains in-situ during healing. This study also suggests that late induction of apoptosis during development of the mature osteoblast phenotype, the differentiated osteocyte is an end point of bone remodelling process during bone graft healing.
Support: This work was supported by a grant from Deutsche Forschungsgemeinschaft, Germany (Grant numbers KU 941/2-1 and KU 941/2-3).