Functional Reconstruction Of Segmental Defects Of Mandible Secondary To Tumor: An Experimental Study On Dogs

ObjectiveFunctional reconstruction of mandible defects after tumor resection is one of the most challenging problems faced by oral & maxillofacial surgeons. For the patients with benign and easy-recrudescent tumor of mandible, reimplantation of frozen autogenous mandible is a suitable way to kill the residual neoplastic cell, prevent the recurrence of the tumor, restore the normal curvature of mandible and reduce the patent's facial malformation. With the mature and pervasion of dental implant technology nowadays, we are illuminated to consummate the technology of transplantation of frozen autogenous mandible and try to rebuild the occlusion function of the mandible. It is the objective of our study to explore the feasibility of the transplantation of frozen autogenous mandible with delayed implantation. Materials and methodsOperations were performed to create two defects in the bilateral mandible of 16 dogs. The left defect was grafted by composite transplantation of frozen autogenous mandible (immersed in — 196℃ liquid nitrogen) with fresh cancellous ilium (composite transplantation group, CTG). The right defect was grafted by fresh ilium(iliac transplantation group, ITG). One IMZ? TPS dental implant was placed into the graft of each side. At 3, 6, 9, 12 weeks postoperatively, 4 animals were sacrificed respectively and the grafts with dental implant were harvested for gross observation, X-ray examination and histological evaluation to compare peri-implant bone healing between CTG and ITG. The bony density of peri-implant graft was measured by the X-ray gray extent and the Bone Mineral Density (BMD). ResultsA. Clinical observation: No animal died during or after operations. Primary healing occurred on all of the wounds. Until 12 weeks after implantation, the implants in two different grafts are stable. There is no obvious bony absorption in the CTG and the bone surface of CTG is smooth. The continuity of the mandibular inferior borderof CTG is better than that of ITG.B. X-ray imageology observation: There is no absorbing bone density reducing image of peri-implant at each stage. The quantified X-ray gray extent display obvious variation of interfacial bone density between two kinds of grafts at 3 weeks, 6 weeks and 9 weeks after implantation. The CTG obviously surpasses the ITG. At 12 weeks after the implantation, there is no significant difference between the peri-implant bones of both sides.C. Histological observation: There is satisfactory osseointegration between the implants and the two kinds of grafts. The healing style of peri-implant bone is similar.D. BMD: The BMD of peri-implant graft of CTG is higher than that of ITG. But with the time prolonging, the difference is diminishing. Until 12 weeks after implantation, the difference is not obvious.ConclusionComposite transplantation of frozen autogenous mandible can recover the anatomic form of the mandible. The implant can form good osseointegration with composite transplantation of frozen autogenous mandible following delayed implantation.