Botulinum Toxin Injections into the Masseter and Temporalis Muscles VS. Oral Methocarbamol for Temporomandibular Myofascial Pain in Adults: A Randomized Clinical Trial

Background/Objectives: Treatment of temporomandibular myofascial pain includes physical therapy, the use of occlusal splints, pharmacological management, and botulinum toxin type A (BTX-A) injections. The aim of this clinical trial was to determine whether BTX-A provides greater clinical benefit than methocarbamol in the management of myofascial pain. Methods: A randomized clinical trial with two parallel groups was conducted, including 235 patients: control group (methocarbamol, n = 111) and intervention group (BTX-A, n = 124). Pain perception was assessed through the number of trigger points detected in the masseter and temporalis muscles, the McGill Pain Questionnaire, and the visual analog scale (VAS). Oral opening was measured using the TheraBite Range-Of-Motion scale in millimeters. Results: Both groups showed significant within-group decreases in overall pain intensity (VAS) and increases in maximum mouth opening (p < 0.001). Baseline-adjusted comparisons at five weeks showed no significant between-group differences in pain (VAS: p = 0.130) or maximum mouth opening (TheraBite: p = 0.125). In an exploratory analysis by muscle site, without correction for multiple comparisons, the BTX-A group showed a greater reduction in active trigger points in the right masseter (p = 0.028) and right temporalis (p = 0.009) but not in the left-sided muscles (p > 0.05). Conclusions: Both BTX-A and methocarbamol were associated with significant improvements in overall pain intensity and maximum mouth opening, with no statistically significant between-group differences at five weeks. The greater reduction in right-sided trigger points observed with BTX-A is an exploratory finding that may reflect multiplicity and requires confirmation.