The impact of dental therapy timelines and irradiation dosages on osteoradionecrosis in oral cancer patients: A population-based cohort study.

OBJECTIVES: This study aimed to investigate how different timelines of various dental therapies were related to osteoradionecrosis development under consideration of radiotherapy dosage in patients with oral cancer. MATERIALS AND METHODS: A total of 7,107 oral cancer patients were enrolled, including 88 osteoradionecrosis patients treated with low radiotherapy dosages (<60 Gy) or high radiotherapy dosages (>/=60 Gy), from the Longitudinal Health Insurance Database for Catastrophic Illness Patients of Taiwan. Cox proportional hazard regression was used to compare the osteoradionecrosis risk of various dental treatment timelines under different irradiation dosages. RESULTS: In the oral cancer population with low irradiation dosages (<60 Gy), performing periodontal therapy combined with irradiation significantly raised the risk of osteoradionecrosis by 2.21-fold. Starting radiotherapy within three months after dental surgery greatly increased the risk of developing osteoradionecrosis by 1.87-fold. The oral cancer patients treated with high radiation doses (>/=60 Gy) receiving dental surgery within one month prior to radiotherapy had a significantly raised osteoradionecrosis occurrence by 1.60-fold. While the dental surgery was performed during the radiotherapy course, the risk of osteoradionecrosis was greatly increased by 2.21-fold. CONCLUSION: For oral cancer patients, performing dental surgery within three months before radiotherapy might significantly induce osteoradionecrosis. Patients that were treated with high irradiation dosages (>/=60 Gy) had a higher tendency to develop osteoradionecrosis if they received dental surgery during radiotherapy. Those who were treated with low radiation dosages (<60 Gy) and received periodontal therapy during radiotherapy might have an increased risk in developing osteoradionecrosis.