Can Photobiomodulation Therapy Reduce Salivary Nitrite in Oral Mucositis? A Systematic Review

Background: Oral mucositis (OM) is a frequent and debilitating adverse effect of cancer treatments, primarily mediated by oxidative stress and inflammatory pathways involving reactive oxygen species (ROS) and nitric oxide. Photobiomodulation (PBM) therapy has emerged as a potential intervention to mitigate OM severity by regulating these mechanisms. This review examines the influence of PBM on salivary nitrite concentrations-a key biomarker of oxidative stress-in patients with OM. Methods: A systematic literature search was conducted across PubMed and the Cochrane Library, encompassing clinical trials published up to June 2025. Included studies investigated the effects of PBM on salivary nitrite levels in patients receiving anticancer therapy. Methodological quality was assessed using the Revised Cochrane Risk of Bias tool (RoB 2.0). Results: Three studies satisfied the inclusion criteria. Although variations existed among the studies regarding anticancer treatment modalities and PBM irradiation parameters, all consistently reported a reduction in salivary nitrite levels following PBM therapy. Conclusion: PBM therapy appears effective in alleviating OM severity, potentially attributable to its capacity to decrease salivary nitrite concentrations. Additional research is warranted to validate these preliminary findings and optimize PBM protocols for clinical implementation.