Osteoradionecrosis of the mandible: Risk Factors related of the treatment of 321 cases of carcinoma of the oral cavity and the oropharynx

Osteoradionecrosis (ORN), a severe complication of radiation treatment of oral cavity and oropharynx carcinomas, should be prevented. We observed the complication in 23 among the 321 patients we treated (7% occurence rate). Therefore we looked for factors associated with a higher incidence of ORN. Among risk factors was the use of interstitial implant alone or associated to an external irradiation, and high fractional dose above 3 Gy per fraction (13,26 and 14% incidence rate of ORN, respectively). Another risk factor was the association of a surgery with bone resection and irradiation (12% incidence rate of ORN). Incidence of ORN was 17% in the carcinomas of oral cavity versus 6% in oropharynx carcinomas. However, when the treatment modalities were identical (external irradiation alone) there was no difference with respect to the necrosis risk between oral cavity and oropharynx (8% and 6% incidence rate). Size of the tumor, dental status (total extractions or conservative treatment with fluoridation), use of an induction chemotherapy) did not modify the incidence of ORN. Then we conducted that interstitial radiation therapy associated to external irradiation or high fractional dose radiotherapy and surgery with bone resection before irradiation are the main causes of ORN