The effectiveness of lower-level laser therapy on the treatment of minor recurrent aphthous ulcers: a systematic review and meta-analysis

Recurrent aphthous stomatitis (RAS) is the most common oral ulcer, causing pain, impaired function, and reduced quality of life. Conventional treatments offer only partial relief and frequent recurrence. This study aimed to systematically evaluate the efficacy of LLLT in minor recurrent aphthous ulcers (mRAU). A systematic search of PubMed, Cochrane Library, Embase, Scopus, and Web of Science was performed up to January 2025. Randomized controlled trials (RCTs) comparing LLLT with sham laser or conventional medication were included. Pain relief was the primary outcome; healing time, ulcer size, and functional recovery were secondary outcomes. Meta-analyses, subgroup analyses, meta-regression, and sensitivity analyses were performed to explore heterogeneity. Twenty-one RCTs involving 810 patients were analyzed. LLLT significantly reduced pain immediately and at days 1-3, with stronger effects in split-mouth designs, sham-controlled groups, and single-session trials. Healing time was also significantly shortened. No consistent benefits were observed for ulcer size or functional recovery. Sensitivity analyses confirmed robust results despite heterogeneity. Several studies applied CO₂laser at low power and short exposure, classified as "quasi-low intensity laser therapy.". LLLT is effective in reducing pain and accelerating healing in mRAU, and a single session may be clinically adequate. However, its impact on ulcer size and functional recovery remain unclear. Well-designed RCTs with standardized protocols and sham controls are needed.