Effect of Photobiomodulation in Patients with Temporomandibular Dysfunction Refractory to Botulinum Toxin Treatment: A Non-Controlled Multicentric Pilot Study

<b>Background/Objectives</b>: Temporomandibular disorders are a heterogeneous group of degenerative musculoskeletal conditions that present a series of symptoms such as pain, dysfunction of the masticatory muscles and/or temporomandibular joints, structural abnormalities, and limitation or alteration of mandibular movements. The objective of this study was to evaluate the efficacy of photobiomodulation therapy with low-power laser in patients refractory to treatment with botulinum toxin type A. <b>Methods</b>: A multicenter prospective experimental pilot study was proposed, in which 10 patients between 33 and 68 (50 ± 11.2) years old participated, assigned to a laser group (940 nm diode laser) who had previously been treated with a minimum of three doses of botulinum toxin type A without obtaining positive results. The patients underwent four photobiomodulation sessions over 4 weeks (registered at ClinicalTrials NCT06915064). Painful symptoms were evaluated using a visual analog scale at different locations, the pressure pain threshold using algometry, and the maximum vertical mandibular movement determined using digital calipers. The results were recorded four weeks after the end of treatment. Adverse effects were also evaluated. <b>Results</b>: Pain in the masticatory muscles was reduced in 70% of patients with statistically significant values (<i>p</i> = 0.002); a total of 60% of patients showed a considerable reduction in joint noise with outstanding statistical significance (<i>p</i> = 0.015). The majority of participants reported a reduction in the intensity of headaches after treatment. However, it only produced a slight improvement in maximum mouth opening and lateral excursions. Algometric values in the masticatory muscles showed improvement only in the left-sided irradiated muscles. <b>Conclusions</b>: Photobiomodulation therapy is a non-invasive treatment option for temporomandibular disorders that generates positive effects in cases refractory to treatment with botulinum toxin type A.