Comparative efficacy of photobiomodulation therapy and transcutaneous electrical nerve stimulation for temporomandibular disorders: a CONSORT-based methodological appraisal

Temporomandibular disorders (TMDs) are among the most common causes of chronic orofacial pain. Although photobiomodulation therapy (PBMT), traditionally referred to as low-level laser therapy (LLLT), and transcutaneous electrical nerve stimulation (TENS) are widely used conservative modalities, their comparative efficacy remains uncertain due to inconsistent evidence. This systematic review compared the efficacy of both therapies and critically appraised the reporting quality and selected methodological characteristics of the included clinical studies. A systematic review was conducted in accordance with PRISMA guidelines, with the protocol registered in PROSPERO. Clinical trials comparing TENS and PBMT were searched in Medline, Web of Science, Scopus, Cochrane, and Embase databases using the descriptors "low-level laser therapy," "photobiomodulation," "transcutaneous electrical nerve stimulation," and "temporomandibular joint disorders," without restrictions on publication year or language. The reporting quality and selected methodological characteristics of the included studies were critically appraised using a CONSORT-based assessment framework. A total of 402 records were identified, of which 14 met the inclusion criteria, comprising 620 patients with joint pain, muscle pain, and/or disc displacement. A greater number of included studies reported numerically larger improvements in pain relief and maximum jaw opening following PBMT than TENS. However, twelve of the fourteen included studies were classified as Level III, indicating limited reporting quality according to the adapted CONSORT-based methodological appraisal framework. Substantial heterogeneity in diagnostic characteristics, treatment protocols, and outcome assessment limited direct comparisons between interventions. Overall, the available evidence suggests that both PBMT and TENS may improve pain and mandibular function in patients with temporomandibular disorders. However, these findings should be interpreted cautiously, as the absence of quantitative synthesis and the substantial clinical and methodological heterogeneity preclude definitive conclusions regarding the comparative efficacy or superiority of either modality.