Post-radiation Dental Lesion Severity: Association with Tooth-level Radiation Dose

Objective: To evaluate the unique contribution of tooth-level radiation dose on the severity of post-radiation dental lesions. Methods: At the end of year two of a five-year investigation, seventy-one subjects who had received head and neck radiotherapy were evaluated concerning individual tooth-level radiation dose, elapsed time after radiation, xerostomia, frequency of topical fluoride, and oral hygiene status. Subjects' computerized radiotherapy treatment plans were used to calculate the cumulative dose for each individual tooth. Subjects' teeth were also evaluated using an index developed to assess post-radiation tooth destruction and associated restorations. Tooth destruction was operationalized as a mean tooth surface score (MSS). Tooth restoration was operationalized in a similar manner as a mean restoration score (MRS). Descriptive statistics were used to characterize the subject population. In order to account for the nesting of teeth within individuals and account for radiation dose varying for different teeth within individuals, a linear mixed model approach with spatial covariance matrix was used. A significance level of p ≤.05 and Akaike's Information Criterion were used to determine the final model. Results: Subjects (22 females, 49 males), ranged in age from 18-82; a total of 1420 teeth were evaluated. Elapsed time since radiation varied from 1-162 mo; individual tooth-level radiation doses ranged from 0-80 Gy. Results showed there was a significant main effect of dose on tooth destruction (MSS) after controlling for other covariates such as elapsed time, oral hygiene, and fluoride frequency. In contrast, there were no significant factors associated with the restoration score (MRS). Conclusions: The preliminary evidence suggests that radiation dose might be linked to the severity of post-radiation lesions. Supported in part by NIH/NIDCR K23 DE01623