Registry to Collect Data on Patients Undergoing Segmental Mandibular Defect Reconstruction Following Oral Squamous Cell Carcinoma Resection and Drugs-induced Osteonecrosis

Inclusion Criteria: * The study includes patients with an initial pathological/histologic diagnosis of mandibular involvement by oral tumors (such as OSCC, osteosarcoma, and ameloblastoma), bisphosphonate- or immunomodulatory drug-induced osteonecrosis, and mandibular lesions from metastatic conditions originating from other sites including lung, breast, prostate, or kidney. * Age 18 years and older * Bisphosphonate related osteonecrosis of the mandible * Immunomodulatory drugs induced mandibular osteonecrosis * Patients presented with ameloblastoma affecting the mandible * Patients presented with osteosarcomas of the mandible * Patients presented with oral metastases related mandibular lesions that are indicated for segmental resection, common primary tumor sites include lung, breast, prostate and kidney * Undergoing primary curative treatment with segmental resection of the mandible ≥2 cm * Intention to undergo mandibular reconstruction with autologous bone using a primary (one-stage) or secondary (two-stage) approach * Informed consent obtained, ie: * Ability to understand the content of the patient information/ICF * Willingness and ability to participate in the clinical investigation according to the registry plan (RP) o Signed and dated IRB/EC approved ICF OR * Written consent provided according to the IRB/EC defined and approved procedures for patients who are not able to provide to provide independent written informed consent Exclusion Criteria: * Tumors affecting the condyle * Patients under palliative care * Previous extensive mandibular surgeries (including reconstructions, e.g., TMJ replacement) that may potentially confound the outcome measures Intraoperative exclusion criteria: * Nonsegmental mandibular defect (eg. box resection/partial resection) * Segmental mandibular defect of less than 2 cm * Mandibular defects extending beyond the sigmoid notch into the condyles Additional exclusion criterion: • No osseous reconstruction with autologous bone performed within 18 months from resection