(1) Background: The healing properties of cannabidiol (CBD) have been known for centuries. In this study, we aimed to evaluate the efficiency of the myorelaxant effect of CBD after the transdermal application in patients with myofascial pain. (2) Methods: The Polish version of the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD Ia and Ib) was used. A total of 60 patients were enrolled in the study and were randomly divided into two groups: Group1 and Group2. The average age in Group1 was 23.2 years (SD) = 1.6 years) and in Group2, it was 22.6 years (SD = 1.86). This was a parallel and double-blind trial. Group1 received CBD formulation, whereas Group2 received placebo formulation for topical use. The masseter muscle activity was measured on days 0 and 14, with surface electromyography (sEMG) (Neurobit Optima 4, Neurobit System, Gdynia, Poland). Pain intensity in VAS (Visual Analogue Scale) was measured on days 0 and 14. (3) Results: in Group1, the sEMG masseter activity significantly decreased (11% in the right and 12.6% in the left masseter muscles). In Group2, the sEMG masseter activity was recorded as 0.23% in the right and 3.3% in the left masseter muscles. Pain intensity in VAS scale was significantly decreased in Group1: 70.2% compared to Group2: 9.81% reduction. Patients were asked to apply formulation twice a day for a period of 14 days. (4) Conclusion: The application of CBD formulation over masseter muscle reduced the activity of masseter muscles and improved the condition of masticatory muscles in patients with myofascial pain.
Keywords: CBD; EMG; TMD; bruxism; cannabidiol; masseter muscle; myofascial Pain.