Impaired urease-mediated alkali generation following radiotherapy in head and neck cancer patients: a pilot salivary biochemical analysis

Introduction Radiotherapy for head and neck cancers is associated with significant alterations in the oral environment, including salivary dysfunction. Urease-mediated hydrolysis of urea represents a key alkalinogenic pathway that contributes to plaque pH homeostasis. However, its behaviour across different stages of radiotherapy remains insufficiently explored. This study aimed to evaluate salivary urea concentration and urease activity in patients undergoing radiotherapy and to assess their potential role in altering oral biochemical balance. Methods 48 patients were divided into four groups (n = 12 each): healthy controls, pre-radiotherapy patients, early post-radiotherapy patients (< 3 months), and late post-radiotherapy patients (> 6 months). Salivary urea concentration was measured using a colorimetric assay, and urease activity was assessed using a urea depletion method following incubation at 37°C for 60 minutes. Statistical analysis was conducted using one-way ANOVA followed by Tukey’s post-hoc test, with significance set at p < 0.05. Results Mean salivary urease activity varied significantly among study groups (one-way ANOVA: F = 6.271, p = 0.002). Observed differences across groups: the lowest urease activity was recorded in the early post-radiotherapy group (< 3 months) (0.179 ± 0.095). The early post-radiotherapy group exhibited the highest mean urea concentration (26.711 ± 12.454 mMol/L). Conclusion Low urease activity post-radiotherapy indicates a reduced alkaline environment of the oral cavity. While no direct assessment of dental caries was performed, these biochemical alterations may contribute to conditions favourable for plaque acidification and subsequent caries development.