Association of radiation caries burden with time elapsed since completion of radiotherapy in patients with head and neck cancer: A cross-sectional pilot study

Objectives: To assess the burden of dental caries using the Decayed (D) component of the DMFT index and to evaluate its association with time elapsed since completion of radiotherapy. Material and Methods: A cross-sectional pilot study involving 37 head and neck cancer patients who had completed radiotherapy was conducted. Data regarding demographics, tobacco use, awareness of radiation-induced caries, xerostomia severity, and time since radiotherapy. Dental caries burden was measured using the (D) component of the Decayed, Missing, Filled Teeth (DMFT) index. Results: The mean age of participants was 49.46 years, and the mean D score was 4.54 ± 2.83. Patients evaluated 6 months after radiotherapy had a significantly higher caries burden than those evaluated within 3 months (6.92 ± 3.40 vs 3.25 ± 1.26; Mann–Whitney U = 34, p < 0.001). A significant positive correlation was observed between the time elapsed since radiotherapy and the decayed teeth score (r = 0.627, 95% confidence interval [CI]: 0.381–0.791; p < 0.001). After adjustment, the burden of untreated caries was markedly higher among patients assessed at 6 months than at 3 months after radiotherapy. The median decayed-tooth count was 3 (interquartile range [IQR] 3–4) at 3 months versus 6 (IQR 5–8) at 6 months, a difference that was highly significant (Mann–Whitney U = 34.0, p < 0.001. In an unadjusted Poisson model, patients at 6 months had more than twice the decayed-tooth count of those at 3 months (incidence rate ratio [IRR] = 2.13, 95% CI 1.57–2.88, p < 0.001). No significant difference in caries burden was observed across xerostomia grades (Kruskal–Wallis H = 0.943, p = 0.624). Multivariable Poisson regression demonstrated that the time since radiotherapy remained the only independent predictor: patients at 6 months had approximately twice the decayed-tooth count of those at 3 months (adjusted IRR = 2.04, 95% CI 1.43–2.89, p < 0.001). The previously observed association with tobacco use was attenuated and no longer significant (adjusted IRR = 1.02 per year, 95% CI 1.00–1.05, p = 0.112), and neither xerostomia grade nor age was independently associated with the outcome. Only 18.9% of participants were aware of radiation-induced dental caries prior to radiotherapy. Conclusion: A longer interval following completion of radiotherapy was associated with a greater burden of untreated dental care. These findings support early preventive dental interventions, patient education, and structured post-radiotherapy follow-up.