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.

口干和唾液分泌不足是接受头颈放射治疗的患者的常见病状，通常会导致生活质量下降。这项研究旨在评估光生物调节（PBM）是否可以最大程度地减少唾液分泌不足，口干症和唾液质变，并改善短期随访放疗患者的生活质量。21例患者随机分为两组：假手术组（SG）和激光组（LG）。二极管激光器用于口腔内（660 nm，10 J / cm ²，每点0.28 J，40 mW）和口腔外（810 nm，25 J / cm ²，在整个放疗期间，每周三次在唾液腺上施加0.7 J /点（40 mW的功率）。在SG中，仪器的尖端用蓝色橡胶密封以防止光线通过。在开始放疗之前（T1），在第十五次疗程（T2）之后，在放疗结束之后（T3）和放疗后60天（T4），评估了口干燥症和pH，确定了未刺激的唾液流量，并确定了刺激的唾液流量。在刺激的唾液样品中评估了钙，总蛋白，氯化物，钠，钾和淀粉酶和过氧化氢酶活性的浓度。在时间T1和T4评估生活质量。广义估计方程用于评估时间和组之间结果的差异。所有患者表现出恶化的刺激（p = 0.003）和刺激（p  <.001）的唾液流量，口干症（p  <.05）和放疗期间的生活质量（p  = .001）。在时间T3和T4观察到氯化物浓度增加（p  <  0.05），在T3时淀粉酶活性降低（p  <  0.05）。在T3时，LG的未刺激唾液pH高于SG（p  =  .037）。两组之间在唾液流量和成分，口干症或生活质量方面没有差异。我们的结果表明，PBM可能有助于在放射治疗期间保持唾液pH值。