Effects of Photobiomodulation Therapy Irradiation Intensity, Frequency, and Duration on Pain, and Functional Improvements in Patients with Temporomandibular Disorder.

<b><i>Purpose:</i></b> To systematically review and meta-analyze the efficacy of photobiomodulation therapy (PBMT) for temporomandibular disorders (TMDs), focusing on the influence of intensity, frequency, and duration on pain reduction and functional improvement. <b><i>Methods:</i></b> Through a systematic search of PubMed, Cochrane, and EMBASE, we identified randomized controlled trials (RCTs) involving adults with TMD who were treated with PBMT. Ultimately, 40 RCTs were included, and a meta-analysis was conducted using Review Manager 5.4. The primary outcomes included pain, pain-free opening (PFO), maximum-unassisted opening, and maximum-assisted opening (MAO). <b><i>Results:</i></b> PBMT significantly reduced pain at the third assessment (T2). The optimal parameters included wavelengths (951-1070 nm) and output power (below 100 mW). Additionally, PFO and MAO significantly improved at T2. Treatment durations exceeding 10 weeks were most effective for articular-muscular TMDs, whereas shorter durations were more beneficial for purely articular or muscular TMDs. Three to four sessions per week yielded the best outcomes. <b><i>Conclusion:</i></b> Effective pain reduction was achieved with high wavelengths (951-1070 nm), low power (<100 mW), and frequent, long-term treatment (3-4 times per week over 10 weeks). Avoiding high energy consumption over a short period was crucial. This approach is more effective for articular-muscular TMDs than for purely articular or muscular conditions.