Radiation therapy for head and neck cancer leads to gingival recession associated with dental caries

Objective. The aim of this study was to examine effects of radiation therapy (RT) for head and neck cancer (HNC) on periodontal disease and relationships to caries. Study Design. A multicenter prospective observational cohort study (OraRad) was conducted in patients undergoing RT for HNC. Assessments were conducted by calibrated examiners at the pre-RT (baseline) visit (n = 533), the 12-month visit (n = 414), and the 24-month visit (n = 365). Results. The average whole mouth mean (standard error (SE)) distance from the cementoenamel junction to the gingival margin (CEJ-GM) decreased significantly from 0.43 (0.04) mm at baseline to 0.24 (0.04) mm at 12 months and 0.11 (0.04) mm at 24 months (P <= .001). Whole mouth mean (SE) percentage of sites with CEJ-GM distance of <0 mm increased significantly from 23.3% (1.0%) at baseline to 28.5% (1.0%) at 12 months and 30.5% (1.1%) at 24 months (P <= .02). Higher mean radiation dose to the mandible was associated with a greater increase in the percentage of mandibular sites with CEJ-GM distance of <0 mm (P = .003). Both mean CEJ-GM distance and the percentage of sites with a CEJ-GM distance <0 mm were strongly associated with whole mouth mean proportion of decayed, missing, and filled surfaces, as well as proportion of decayed or filled facial/buccal surfaces specifically, (P < .001), with greater gingival recession associated with increased caries. Conclusions. RT for HNC leads to mandibular gingival recession in a dose-dependent manner. This gingival recession may contribute to increased risk for cervical caries seen in these patients.