Longitudinal periodontal deterioration and salivary dysfunction following head and neck radiotherapy: a prospective...

Head and neck radiotherapy (RT) may induce persistent alterations in periodontal tissues, salivary gland function, and dental integrity, thereby contributing to progressive oral disease in head and neck cancer (HNC) survivors. However, comprehensive longitudinal evidence integrating periodontal, salivary, and dental outcomes remains limited. To evaluate longitudinal changes in periodontal health, salivary function, dental outcomes, and oral health-related quality of life (OHRQoL) during the first year following RT. This prospective multicenter cohort study included 98 patients with HNC receiving external-beam RT. Clinical attachment level (CAL), probing pocket depth (PPD), bleeding on probing (BOP), gingival index, unstimulated salivary flow rate, xerostomia severity, radiation-associated caries, and OHRQoL were assessed at baseline, end of RT, and 3-, 6-, and 12-month follow-up visits. Longitudinal analyses were performed using mixed-effects regression models. Eighty-eight participants completed the 12-month follow-up. Mean CAL increased from 2.30 to 3.02 mm (p < 0.001), while PPD, BOP, and gingival index values also increased significantly over time. Mean unstimulated salivary flow rate decreased from 0.36 to 0.15 mL/min (p < 0.001), accompanied by worsening xerostomia severity. Radiation-associated caries developed in 76.1% of participants and tooth loss occurred in 30.6% during follow-up. Mean OHIP-14 scores increased from 23.44 to 44.44 (p < 0.001). Higher salivary flow independently reduced the likelihood of radiation-associated caries development (OR = 0.78, p = 0.009). Head and neck RT was associated with progressive periodontal deterioration, salivary gland dysfunction, increased radiation-associated dental disease, and impaired OHRQoL during 12 months of follow-up. These findings support the need for longitudinal preventive oral healthcare in HNC survivors.