Augmentation of Peri-implant Bone Defects with Different Bone Grafts and Guided Bone Regeneration:

Objective; The present investigation was designed to evaluate the regenerating effects of chip bone grafts harvested from implant drilling and biomaterials with or without combined application of guided bone regeneration (GBR) for the augmentation of peri-implant bone defects. Materials and methods; Four mongrel dogs were used. After the mandibular premolars were extracted for 12 weeks, surgical implantation of 4 titanium implants was performed on each side of the mandible. Chip bone was collected during the drilling procedure. Three-wall bone defects, about 2 mm high, 2 mm wide, and 3 mm long, were created at the buccal side of each implant. The osteotomy sites were separately filled with autogenous chip bone, Bio-oss mineral bone or mixture of both except one defect was left empty. The operation areas of the left mandibula were covered with titanium membranes. The right mandibles without membrane were used as controls. The dogs were sacrificed at either 9 or 16 weeks after the second operation. After the specimens containing experimental implants were resected, the resorption amount of the bone graft was measured. Then the specimens were processed for ground sectioning. The sections were stained with methylene blue and alkalescence fuchsin. Histological examination was performed and photographs were taken under photomicroscope. Results; The mean vertical distances of each bone defects were 2.64±0.17 mm in the D1 (control) group, 1.81±0.21 mm in D2 (autograft) group, 1.72±0.34 mm in D3 (Bio-oss) group, 1.51±0.22 mm in D4 (mixture) group. Statistical analysis demonstrated that there was significant difference between the results of D1 and the results of other three groups (p<0.01). No statistical differences were revealed between autograft group and Bio-oss group, as well as Bio-oss group and mixture group. It is confirmed there was significant difference between autograft group and mixture group (p<0.05). Histological observations revealed both quantity and quality of regenerated bone in the mixture grafted specimens were superior to that of single Bio-oss grafted or single autologous bone grafted specimens. Whether the membranes were utilized or not, vertical distances of the defects were larger at 16 weeks than those at 9 weeks in all the groups. Bone grafts with titanium membranes were subjected to greater resorption than those without membrane coverings at either 9 weeks or 16 weeks. Statistical analysis indicated there were significant differences in the results between the two groups (p<0.01). Conclusions: This investigation demonstrated the utilization of bone chip collected during implant drilling in combination with biomaterial was a feasible methods for repairing the limited bone defect around the implant. Using the mixture of autogenous bone and Bio-oss mineral as grafting material may significantly promote the bone regenerating effects. The functions of titanium membrane need to be further investigated.