The use of botulinum toxin for the treatment of temporomandibular disorder.

PURPOSE The aim of this study was to evaluate the response of patients with temporomandibular disorders to Botulinum toxin A (BTX-A) therapy. METHODS The 15 subjects enrolled in this uncontrolled study were diagnostically categorized and treated with 150 units of BTX-A. Both masseter muscles received 50 units each under eletromyographic (EMG) guidance. Similarly, both temporalis muscles were injected with 25 units each. Subjects were assessed at 2-week intervals for 8 weeks. Outcome measures included subjective pain by visual analog scale (VAS), measurement of bite force, interincisal opening, tenderness to palpation, and a functional index based on multiple VAS. RESULTS All mean outcome measures, with the exception of bite force, showed a significant (P = .05) difference between the preinjection assessment and the four follow-up assessments. No side effects were reported. CONCLUSIONS BTX-A injections produced a statistically significant improvement in four of five measured outcomes, specifically pain, function, mouth opening, and tenderness. No statistically significant changes were found in mean maximum voluntary contraction or in paired correlation of factors such as age, sex, diagnosis, depression index, or time of onset.