Effectiveness of low-level laser therapy on temporomandibular disorders. A systematic review of randomized clinical trials

Objective: This study aimed to systematically evaluate the efficacy of LLLT in the management of TMD, focusing on its impact on pain reduction and functional improvement. Additionally, this review sought to identify the most effective laser parameters (wavelength, energy density, and duration of therapy) and compare LLLT outcomes with conventional treatment modalities. Methods: A comprehensive search was conducted across PubMed, Scopus, Web of Science, and EBSCO databases until December 2024. Randomized controlled trials (RCTs) that evaluated LLLT's effects on pain (via Visual Analog Scale) and vertical aperture (VA) were included. The risk of bias was assessed using Cochrane's RoB 2 tool. Results: This systematic review analyzed 44 randomized clinical trials (RCTs) with 1,816 participants, confirming that low-level laser therapy (LLLT) significantly reduces pain intensity (60-70 % decrease on the Visual Analog Scale) and improves mandibular function (10-20 % increase in maximum mouth opening). The most effective laser wavelengths ranged from 810 to 940 nm, with energy densities of 3-12 J/cm2. Longer treatment durations (>4 weeks) provided more sustained benefits. Compared to occlusal splints, NSAIDs, and TENS, LLLT showed superior or comparable pain relief with fewer side effects. However, variability in laser parameters and protocols remains a limitation. Conclusion: LLLT is a safe and effective non-invasive treatment for TMD, offering substantial benefits in pain management and functional recovery. Standardized protocols based on optimized dosimetry are needed to enhance clinical outcomes further.