Effect of photobiomodulation on salivary flow and composition, xerostomia and quality of life of patients during head and neck radiotherapy in short term follow-up: A randomized controlled clinical trial

Xerostomia and hyposalivation are frequent conditions in patients undergoing head and neck radiotherapy, which usually lead to a worsening of quality of life. This study aimed to assess whether photobiomodulation (PBM) can minimize hyposalivation, xerostomia and qualitative changes on saliva and improve quality of life in patients undergoing radiotherapy in short-term follow-up. Twenty-one patients were randomly divided into two groups: sham group (SG) and laser group (LG). A diode laser was used for intra- (660 nm, 10 J/cm2, 0.28 J per point, 40 mW) and extra-oral (810 nm, 25 J/cm2, 0.7 J per point, 40 mW) applications over the salivary glands, three times a week, during the entire radiotherapy period. In SG, the tip of the instrument was sealed with blue rubber to prevent the passage of light. Xerostomia and pH were evaluated and unstimulated and stimulated salivary flow was determined before the start of radiotherapy (T1), after the 15th session (T2), after the end of radiotherapy (T3) and 60 days after radiotherapy (T4). Concentrations of calcium, total proteins, chloride, sodium, potassium and amylase and catalase activities were evaluated in stimulated saliva samples. Quality of life was assessed at times T1 and T4. Generalized estimating equations were used to assess differences in the outcome between times and groups. All patients showed worsening in unstimulated (p = .003) and stimulated (p < .001) salivary flow, xerostomia (p < .05) and quality of life during radiotherapy (p = .001). An increase in chloride concentrations was observed at times T3 and T4 (p < 0,05), and a reduction in amylase activity at T3 (p < .05). Unstimulated saliva pH was higher in LG than SG at T3 (p = .037). No difference between groups was noted in relation to salivary flow and composition, xerostomia or quality of life. Our results suggest that PBM may help in preserving salivary pH during radiotherapy.