Abstract: PURPOSE: To investigate the clinical characteristics, treatment, classification and stage of osteoradionecrosis of the jaws. METHODS: Using BS classification and Stage, we retrospectively studied the clinical data of 120 ORNJ cases treated from Jan. 2003 to Jan. 2013. RESULTS: Mandibular necrosis was significantly more than maxilla and upper-lower jaws, account for 99, 14 and 7, respectively. Cumulative radiation dose ranged from 35 to 148Gy, with a median dose of 68.1Gy, and 69(57.5%) cases received more than 60Gy. In majority of patients (64.2%), osteonecrosis occurred first to two years after radiotherapy, however, also 20.0% patients osteonecrosis occurred more than five years after radiotherapy. According to BS classification, none of patient belonged to StageⅠ; Stage Ⅱ patients accounted for 13.3% (n=16), and 14 cases were treated by sequestrum scaling and simple sequestrum extensive resection; Stage Ⅲ patients accounted for 76.7% (n=92), and 71 cases were treated by sequestrum extensive resection, and 47 cases treated with simultaneous vascularized flap; Stage Ⅳ patients accounted for 10.0% (n=12), 10 cases were treated by sequestrum extensive resection and immediately vascularized flap transplantation. CONCLUSIONS: Osteoradionecrosis occurs more easily in unilateral mandible, especially the body and partial ramus. In majority of patients, osteoradionecrosis occurred first to two years after radiotherapy. The currently best treatment methods for ORNJ are extensive sequestrum resection combined immediately vascularized flap transplantation.Supported by National Natural Science Foundation of China (81271112, 30973341), Development Foundation of Shanghai Municipal Human Resources and Social Security Bureau (201312) and SMC Rising Star-A Scholar of Shanghai Jiao Tong University (201312).

Key words: Jaw bone, Osteoradionecrosis, BS classification, Stage