Effect of botulinum toxin-A on pain and mouth opening following surgical intervention in oral submucous fibrosis - A controlled clinical trial.

The purpose of this trial was to study the effect on pain and mouth opening of intramuscular injection of botulinum toxin-A into masticatory muscles following surgical intervention in oral submucous fibrosis (OSMF) cases. Injections of either botulinum toxin A (BTX-A) (study group) or normal saline (control group) were given 2 weeks prior to surgical intervention in OSMF patients, into the bilateral masseter and temporalis muscles. All patients were evaluated for pain and ease of active physiotherapy at 1 week and 1, 3, and 6 months after surgery using a numerical rating scale and appropriate questionnaires, with comparisons made between the study and control group patients. Electromyographic studies of the masticator muscles were also carried out in all patients before injection, and at 1 month and 6 months after injection. 20 OSMF patients were equally divided into study and control groups (n = 10 each). At 1, 3, and 6 months after surgery, the study group patients showed significantly greater decreases in pain (p-values of 0.007, 0.001, and 0.005, respectively) and greater ease in physiotherapy compared with the control group. EMG recordings of masticator muscles showed a transient drop in microvolt value in the study group 1 month after injection, unlike the control group recordings. It was concluded that preoperative BTX-A injection was a good addition to surgical therapy in the patient group.