Mandibular bone changes induced by head and neck radiotherapy

Abstract

The mandible is inevitably affected by radiation during radiotherapy of head and neck cancers. Surveys have shown that most of the emphasis has been on osteoradionecrosis (ORN), while the other bony changes occurring in this area have been largely ignored. In this study we examine the radiologic changes in the mandible of irradiated patients using panoramic radiography and compare it with the mandible in non-irradiated cases. Mandibular bone changes of 48 patients who had received therapeutic radiation for head and neck cancer were assessed. We measured the width of the cortex and the width of the mandibular canal on panoramic radiographs and assessed the changes by comparison with the mandibular bones of non-irradiated subjects. Clinical evaluations were performed for assessing maximum jaw opening, masticatory muscle tenderness, and presence of mucosal ulcers and/or exposed bone in the oral cavity. Paired t-test, Chi-square test, and Mann-Whitney test were used for statistical analysis. P < 0.05 was taken to indicate statistical significance. There was no evidence of mucosal ulceration or exposed bone in irradiated patients. There was significant relationship between the number of years after radiotherapy and the degree of limitation of mouth opening (P = 0.000). Receipt of concurrent chemotherapy did not seem to have any additive effect on the width of mandibular canal or the thickness of the mandibular cortex. Reduction in the width of the mandibular cortex and dimensions of the inferior alveolar canal could be considered as one of the effects of head and neck radiotherapy.