Does Botulinum Toxin Type–a Improve Mandibular Motion and Muscle Sensibility in Myofascial Pain Tmd Subjects? A Randomized, Controlled Clinical Trial

To demonstrate if botulinum toxin type A (BoNT-A) improves mandibular range of motion and muscle sensibility to palpation in refractory myofascial pain (MFP) patients. METHODS: Eighty consecutive female subjects with refractory MFP, were randomly divided into four equal groups (n=20): BoNT-A low (BoNTA-L/10 U in each temporalis and 30 U in each masseter), BoNT-A medium (BoNTA-M/20 U in each temporalis and 50 U in each masseter), BoNT-A high (BoNTA-H/25 U in each temporalis and 75 U in each masseter) and saline solution 0.9% (SS, placebo control group/0.4 mL in each temporalis and 0.6 mL in each masseter). Clinical measurements of the mandibular movements included: pain-free opening, maximum unassisted and assisted opening, and right and left lateral movements. Palpation tests were performed bilaterally in masseter and temporalis muscle. Results were expressed as median, minimum, maximum, and means ± standard deviation (SD). Chi-Square Test was used to compare differences among groups. A 5% probability level was considered significant in all tests RESULTS: Regardless of dose, all parameters of mandibular range of motion significantly improve after 180 days in BoNT- A groups, when compared to the control group. Pain to palpation on muscles, significantly reduced in all BoNT- A groups regardless of dose, when compared to the control group, after 28 and 180 days of treatment. CONCLUSIONS: Independent of doses, BoNT-A improved mandibular range of motion and muscle sensibility to palpation in refractory MFP patients when compared to SS injections.