Botulinum Toxin Type A for Myogenous Temporomandibular Disorders, Focusing on the Duration of Clinical Effects and...

Botulinum toxin type A (BoNT-A) has been increasingly investigated as a therapeutic option for myogenous temporomandibular disorders (TMD), yet uncertainties remain regarding the duration of its clinical effects and the relevance of dosing parameters.

To systematically evaluate the clinical effects, duration of action, and dosage parameters of BoNT-A in the management of myogenous temporomandibular disorders.

This systematic review followed PRISMA 2020 guidelines and was registered in PROSPERO. Electronic searches were conducted in PubMed/MEDLINE, Embase, Scopus, Web of Science, and LILACS. Randomized clinical trials evaluating BoNT-A for myogenous TMD were included. Study selection, data extraction, and risk of bias assessment using the Cochrane Risk of Bias 2 (RoB-2) tool were performed independently. Due to methodological heterogeneity, a qualitative synthesis was conducted.

Ten randomized clinical trials were included. Pain was assessed using validated instruments, including the Visual Analog Scale, Characteristic Pain Intensity, and Numeric Rating Scale. Pain reduction over time was reported in both BoNT-A and control groups, including placebo and conservative therapies. In placebo-controlled trials, BoNT-A did not consistently demonstrate superiority over saline injections. Greater pain reductions were reported in studies involving refractory myofascial pain. Improvements in mandibular function were observed in both intervention and control groups. Clinical effects were generally reported to persist for 8 to 24 weeks. Current evidence is insufficient to determine whether a clinically relevant dose-response relationship exists across the evaluated regimens. Adverse events were mostly mild to moderate and transient.

Current evidence does not support the routine use of BoNT-A as a first-line treatment for myogenous temporomandibular disorders. Its use may be considered in selected refractory cases after failure of conservative therapies.