Three Photobiomodulation Wavelengths (635, 940, and 1064 nm) on Chronic Myogenic Temporomandibular Disorder

Temporomandibular disorders (TMDs) are among the most common musculoskeletal conditions associated with chronic orofacial pain and functional disability. Chronic Myogenic TMD (MTMD) is the most prevalent subtype and is characterized by persistent masticatory muscle pain driven by peripheral and central sensitization mechanisms. Photobiomodulation (PBM) represents a conservative, non-invasive therapeutic modality within the medical management of TMD; however, the wavelength-dependent clinical and muscular effects remain inadequately defined. Aim: To compare the efficacy of three PBM wavelengths (635, 940, 1,064 nm) on pain intensity, mandibular function, surface electromyographic activity (sEMG), and pressure pain threshold (PPT) in patients with chronic myogenic TMD.

Inclusion Criteria: * Patients suffering from chronic myogenic TMD based on diagnostic criteria for diagnosis of temporomandibular joint disorders (DC/TMD) criteria. (pain increases with jaw opening, chewing, or clenching). * Patients suffering of unilateral or bilateral chronic pain (\> 3 months' duration) related to masseter and temporalis muscles(30). * Patients suffering of moderate-to-severe pain intensity ≥ 4 on a 0-10 VAS * Patients that have not responded to conservative modes of treatment during the study and up to 3 months after last intervention. (medications, physiotherapy, splints). Exclusion Criteria: * Patients suffering from chronic systematic conditions that alter pain sensitivity; neurological diseases, pain of dental origin, pregnancy or lactation, high blood pressure, diabetes milletus, rheumatic inflammatory disease, fibromyalgia, obstructive sleep apnea, and restrictions for the use of laser (pacemakers). * Participants on medications that affect pain sensitivity and perception during the last 2 weeks: anticoagulants, analgesics, or antidepressants. * History of surgery, arthropathy (joint disorders), facial trauma, malignant tumors or fractures in the orofacial region, neuropsychological or hormonal problems * Treatments: orthodontics, splints, major occlusal rehabilitation, prosthodontic therapy, previous PBM, TENS therapy, or botox for TMD in the last 6 months.