The association between dental therapy timelines and osteoradionecrosis: a nationwide population-based cohort study

Objectives: The study aimed to investigate the timeline association with specific dental therapy and osteoradionecrosis (ORN) in oral cancer patients. Materials and methods: A total of 7394 oral cancer patients, including 198 ORN subjects, were retrieved from a Longitudinal Health Insurance Database for Catastrophic Illness Patients of Taiwan and were analyzed with the Cox proportional hazard regression to compare the ORN risk of individual dental treatments under different dental treatments. Results: The initial dental treatment time significantly impacted on the risk of ORN in oral cancer patients (P<0.05). Pre-radiotherapy endodontic treatment and post-radiotherapy scaling or subgingival curettage increased ORN prevalence (hazard ratio [HR], 2.28 and 1.77, respectively). Endodontic treatment within 2 weeks to 1 month prior to radiotherapy increased the ORN risk by 5.83-fold. Dental scaling or subgingival curettage initialized from three to 6 months post-radiotherapy raised the ORN prevalence by 2.2-fold. Exodontia initialized within 2 weeks before radiotherapy (HR=1.49) or 1 to 3 months after radiotherapy (HR=2.63) greatly increased ORN prevalence. To perform oral surgery from 3 months pre-radiotherapy to 6 months after radiotherapy increased the 1.85-fold ORN risk. The chemotherapy combined oral surgery increased the ORN prevalence by 2.55-fold. Conclusions: Timing of dental treatment, including pre-radiotherapy endodontic treatment, post-radiotherapy scaling or subgingival curettage, and oral surgery or exodontia before and after radiotherapy, could closely relate to ORN development in oral cancer patients. Clinical relevance: Choosing right time to perform appropriate dental treatment could effectively reduce oral infection and ORN risk.