Effects of low-level laser photobiomodulation on the masticatory function and mandibular movements in adults with temporomandibular disorder: a systematic review with meta-analysis

PURPOSE: To review the effects of low-level laser photobiomodulation on masticatory function and mandibular movements in adults with temporomandibular disorder. RESEARCH STRATEGIES: Search in PubMed, Web of Science, Scopus, EMBASE, Cochrane, LILACS, ScienceDirect, and Google Scholar, using the following descriptors: “temporomandibular joint disorders”, “low-level light therapy”, “low-level laser therapy”, “mastication”, and “mandible”. SELECTION CRITERIA: Randomized clinical trials in adults with temporomandibular disorder, using low-level laser and assessing the mastication and mandibular movements. DATA ANALYSIS: Firstly, the titles and abstracts of all retrieved studies were read. Then, only the studies selected in the first stage were read in full and assessed regarding eligibility. After the selection, the characteristics, methodological quality, and quality of evidence of the studies included in the review were analyzed. In the meta-analysis, the mean amplitude of mouth opening was considered as a measure of intervention effect. RESULTS: The 10 articles included in the review had quite different results one from the other, especially regarding the amplitude of mouth opening, while the mastication was assessed in only one of them. Most studies had a high risk of bias, demonstrating a low methodological quality. Significantly higher results for photobiomodulation were identified in the six studies included in the meta-analysis. CONCLUSION: Due to the scarcity in the literature, there is not enough evidence of the effects of low-level laser photobiomodulation on mastication. As for the mandibular movements, this intervention presented significant results, particularly in the amplitude of mouth opening.