Guidelines for Complications of Cancer Treatment Vol VIII Part B

Osteoradionecrosis of the MandibleDefinition When irradiated bone becomes devitalized and exposedthrough the overlying periosteum or mucosa withouthealing for 3 months, without evidence of recurrence oftumor. The final diagnosis is most often based on a radiologicalevidence of bony necrosis within the radiation field orhistological evidence of necrotic bone at the time ofresection.Incidence The true frequency of ORN is impossible to determinebecause of poor reporting. The overall incidence of ORNhas decreased over the last 3 decades. ORN incidenceover the years has ranged from 3.0-11.8%. ORN is rare in patients who receive less than 60 gray(Gy) radiation therapy (conventional fractionation).However, the incidence maybe higher in patients whoreceive combined chemotherapy and radiation. ORN affects the mandible more than any other bones ofthe face and neck. Its incidence in the mandible isbetween 2% and 22% and affecting the body most often.158