Osteoradionecrosis of the jaw (ORNJ) is a severe iatrogenic outcome of non-vital bone caused by radiotherapy of head and neck malignancies. The concept most widely accepted by clinicians is based on clinical findings: the local lesion where in the absence of tumor recurrence, irradiated bone becomes devitalized, and exposed with inadequate wound healing for a period of 3-6 months (Marx, 1983a(Marx, , 1983bMarx & Johnson, 1987;Wong et al., 1997). Typical clinical features including areas of exposure necrotic bone and ulcerative mucosa, pain or anesthesia, suppuration, intraoral or extraoral fistulae, trismus, pathologic fracture, and varying degrees of local or systemic infection, eventually leads to dysfunction and life threats (Epstein et al., 1987;Store & Boysen, 2000).Osteoradionecrosis (ORN) is a complex metabolic and homeostatic deficiency due to irradiation-induced tissue injury, which is