Effect of Δ9-tetrahydrocannabinol and cannabidiol on myofascial pain modulation in patients with temporomandibular disorder: a prospective crossover study

Abstract

Background Temporomandibular Disorder (TMD) often causes chronic orofacial pain and functional limitations, with conventional treatments providing suboptimal results. Phytocannabinoids such as Δ9-Tetrahydrocannabinol (Δ9-THC) and Cannabidiol (CBD) have analgesic and anti-inflammatory properties, but evidence in TMD is scarce. Objective To evaluate the efficacy of Δ9-THC/CBD therapy in reducing pain and improving mandibular function in TMD patients. Methods Twenty adults with chronic myofascial pain (DC/TMD diagnosis) participated in a blinded, crossover, non-randomized study. Participants underwent two consecutive 90-day phases: placebo followed by Δ9-THC/CBD therapy (1:1 ratio, starting with a dose of 2 mg/day in the first week, gradually adjusting an increase of 2 mg/week until reaching 10 mg/day in the fifth week, sublingually), without washout. Outcomes included pain intensity (VAS), muscle sensitivity (algometry), mandibular function (mouth opening, protrusion, laterality) and pain sensitivity (allodynia/hyperalgesia). Data were analyzed using linear mixed models for repeated measures. Results Δ9-THC/CBD improved all outcomes versus baseline and post-placebo (p ' 0.001; Cohen’s d ' 0.8). Mouth opening increased from 45.9 mm to 49.9 mm; VAS pain decreased from 7.35 to 3.50. Functional pain dropped by ∼90%, with near elimination of allodynia and hyperalgesia. Placebo effects were minimal. Conclusion Δ9-THC/CBD therapy provided substantial analgesic and functional benefits in TMD patients, supporting its potential as a therapeutic alternative. Larger randomized studies are recommended to validate these findings and explore underlying mechanisms.