This 5-year project is specifically designed to investigate the feasibility of reimplantation of autogenous mandibular grafts of large size (6-10 cm) in the adult dog. At present, reconstruction of the mandible following ablative cancer surgery of the anterior floor of the mouth and mandible is difficult, and the results are unsatisfactory due to loss of bone. Preliminary studies by the P.I. indicate that segmental resection and immediate replacement of autogenous mandible subsequent to cryosurgical devitalization in liquid nitrogen results in neoosteogenesis in small (4 cm) grafted segments after 6 months in adult dogs, even when the graft is subjected to radiotherapy. This project will evaluate immediate reimplantation of autogenous mandibular grafts of large size (6-10 cm), determine whether particulate bone marrow and cancellous bone (or PMCB) will benefit the grafted autogenous mandibular segment, compare non-irradiated bone grafts to those compromised by preoperative and postoperative radiotherapy, and analyze the effects of delayed reimplantation. Adult dogs will undergo segmental excision, cryosurgical devitalization, and reimplantation. PMCB grafting will be performed in one-half of all dogs in each of four groups. One group will be immediately reimplanted without receiving any irradiation; one group will undergo preoperative RT; a third group will receive postoperative RT. Reimplantation, with or without radiotherapy, will be delayed three months in the last group. Analysis of results will be carried out by four methods: (1) clinical, (2) radiographic to include x-rays and TC99MDP radionuclide scanning, (3) histopathologic including polerizing light microscopy, and (4) tetracycline fluorescence. Observations of canine mandibular regeneration subsequent to cryosurgical intervention should point the way to possible human application. Novel in this approach is the expected establishment of the patient's own mandibular profile without sacrifice of therapeutic potential in this area of cancer surgery.
