Osteoradionecrosis (ORN) is a severe complication of radiation therapy for head and neck cancer. The current theory in its pathophysiology is thought to be radiation-induced fibroatrophy of the bone. Location of primary tumor, stage of cancer, dose of radiation, oral hygiene, and smoking and alcohol use are risk factors in the development of ORN. Prevention is focused on thorough dental care before, during, and after radiation therapy. Treatment ranges from conservative management with oral rinses and local debridement to radical resection with microvascular free tissue transfer and reconstruction.