Photobiomodulation Irradiation Protocols for Burning Mouth Syndrome: A Systematic Review and Protocol-Level Meta-Analysis of Randomized Trials

OBJECTIVES: To evaluate the effects of photobiomodulation therapy/low-level laser therapy (PBMT/LLLT) on burning mouth syndrome (BMS) and to explore whether irradiation protocol variables modify treatment effects. METHODS: Randomized controlled trials were synthesized according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Cochrane guidance. The protocol was registered in International Prospective Register of Systematic Reviews (PROSPERO) (CRD420261329136). Random-effects meta-analyses evaluated pain, Oral Health Impact Profile-14 (OHIP-14), xerostomia, anxiety, and depression. Irradiation-related subgroup analyses, including wavelength, power, fluence, irradiation time, session frequency, treatment duration, and application mode, were exploratory. Xerostomia and depression were not significantly improved, whereas anxiety showed a modest reduction. Several irradiation protocol variables showed nominal exploratory signals. CONCLUSIONS: PBMT/LLLT may reduce BMS-related pain and improve oral-health-related quality of life. Current evidence supports irradiation protocol standardization but remains insufficient to define an optimal protocol.