LAUSR

OBJECTIVE Osteoradionecrosis of the jaw is a serious late adverse event in patients with head and neck cancer undergoing radiotherapy. The aim of this study is to investigate the relationship between dental status and development of osteoradionecrosis. STUDY DESIGN Multicenter, retrospective observational study. A total of 392 patients with head and neck cancer who underwent radiotherapy were investigated for correlations between the development of osteoradionecrosis and various factors. The cumulative occurrence rate of osteoradionecrosis was calculated by the Kaplan-Meier method and analyzed by Cox regression and log-rank test. RESULTS Osteoradionecrosis developed in 30 of 392 patients. In 23 patients, osteoradionecrosis occurred in the mandibular molar region. A univariate analysis showed that oral or oropharyngeal cancer, jaw radiotherapy dose exceeding 50 Gy, periapical periodontitis, and tooth extraction after radiotherapy were significantly correlated with the occurrence of osteoradionecrosis. Among these, oral and oropharyngeal cancer, periapical periodontitis, and tooth extraction after radiotherapy were significant independent risk factors by multivariate analysis. Further, caries that occurred after radiotherapy and progressed rapidly, resulting in periapical periodontitis, carious stump, or extraction, was a major cause of osteoradionecrosis. CONCLUSION Extraction of mandibular molars with periapical periodontitis before radiotherapy and strict dental management after radiotherapy may reduce the risk of osteoradionecrosis.