Objective Radiotherapy (RT) for head and neck cancer (HNC) within 7 days of tooth extraction is contraindicated because it may increase the risk of osteoradionecrosis of the jaw (ORNJ). However, delayed RT could compromise survival in patients with HNC. By using a national healthcare database, we reviewed the contraindications and analysed other risk factors for ORNJ. Design A retrospective cohort study. Setting By using Taiwan's National Health Insurance Research Database, 5,062 HNC patients with at least one tooth extraction 1-21 days before the first RT day (index day) and without any extractions during or after RT from 2000 to 2013 were included. The patients were divided into two groups according to the time of tooth extraction before the index day: 1-7 days and 8-21 days. Participants Taiwanese patients with head and neck cancer. Main Outcomes Measure Univariate and multivariate Cox proportional hazard regression models were used to evaluate the risk factors of ORNJ. Results The overall incidence of ORNJ in the included patients was 1.03% (mean follow-up duration, 4.07 +/- 3.01 years; range, 1.00-13.99 years). Tooth extraction within 7 days before RT was not associated with increased ORNJ risk (hazard ratio [HR] =0.734;P = .312). Significant risk factors for ORNJ included oral cancer (adjusted HR = 3.961), tumour excision surgery within 3 months before RT (adjusted HR = 3.488) and mandibulectomy within 3 months before RT (adjusted HR = 5.985; allP < .001). Conclusion In a mean follow-up of 4 years, tooth extraction within 7 days before RT for HNC treatment did not increase the ORNJ risk compared with tooth extraction 7-21 days before RT.
