RESUMO
BACKGROUND: Osteoradionecrosis (ORN) of the jaw is currently defined by the development of osteonecrosis in head/neck irradiated patients, regardless of lesion exposure. To diagnose medication-related osteonecrosis of the jaw (MRONJ), a history of any radiation therapy to the jaw region must be ruled out. The aim of this study was to assess the accuracy of current osteonecrosis criteria, while introducing new modifications for improved diagnosis and treatment. METHODS: One hundred and forty-one necrotic lesions were analyzed from patients exposed to bone-modifying agents (BMAs) and/or received head and neck regional radiation therapy, where the maximal dose of radiation exposure to the jaw osteonecrosis site was calculated. Modified diagnostic criteria were used to reassess all cases and a comparison of outcomes was performed using Pearson's Chi-Square/Fisher's exact test. RESULTS: Only in patients with primary head and neck carcinomas did the maximal mean radiation dose in the necrotic jaw site reach ranges associated with ORN formation (>40 Gy), with individual cases showing exposures as low as 0-2 Gy. Based on the modified diagnostic criteria almost 2/3 of the necrotic cases diagnosed as ORN should be diagnosed as MRONJ. CONCLUSIONS: ORN diagnosis should only be considered in cases of radiation exposure >40 Gy to prevent misdiagnosis and suboptimal treatment. A modified criterion for MRONJ diagnosis is recommended where radiation exposure <40 Gy in the necrotic site is included. In cases with exposure >40 Gy and BMA administration, an additional modification to diagnostic criteria of 'medication- and radiation-related osteonecrosis of the jaw', should be used.
