RESUMO
: The present study was conducted to compare between extraoral and intraoral approach for botulinum toxin type A (BTX-A) injection into the lateral pterygoid muscle (LPM) in patients suffering from anterior disc displacement with reduction (ADDWR).Fourteen patients suffering from ADDWR were included in this prospective cohort study. Patients were enrolled randomly into 2 groups according to injection approach; where extraoral used in group I, while intraoral approach used in group II. The LPM was injected with 20 IU BTX-A under electromyography (EMG) guidance. Postoperative evaluation of the patients included: mouth opening assessment, LPM tenderness, temporomandibular joint TMJ (clicking), and tenderness. The LPM insertional EMG activity was assessed. Also, magnetic resonance imaging (MRI) was performed to evaluate disc position. Descriptive and inferential analysis was conducted to compare between groups.There was significant patient's convenience during injection and significant injection time reduction in group II. A slight decrease in mouth opening immediate post-injection followed by significant improvement from 8th weeks post-injection was reported in both approaches. There was a significant improvement in TMJ clicking from 1st-week post-injection with no group difference. The EMG assessment documented LPM hyperactivity pre-injection followed by significantly decreased muscle activity at 8 and 16 weeks post-injection without statistical difference. The MRI showed no change in disc position after injection. CONCLUSION:: The BTX-A injection into LPM is a simple technique that can be used with high success and low complication rate for treatment of ADDWR. The intraoral approach was superior to the extraoral concerning patient convenience and injection duration with no statistical difference regarding other clinical outcomes.