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Introduction: The use of botulinum toxin type A (BTX-A) injection as it is a more recently reported treatment to alter the musculature with the intended effect to weaken the lateral pterygoid muscle (LPM) sufficiently to prevent temporomandibular joint (TMJ) dislocation. This caused a new imbalance between the muscles used for opening and closing the jaws, and mouth opening was slightly limited because of the weakness of the LPM.
Objectives: To evaluate the efficacy of injection of BTX-A as the first choice of treatment for patients with chronic TMJ dislocation not responding to conservative line of treatment.
Materials and methods: A prospective study was conducted on a total of 20 patients complaining of recurrent episodes of chronic TMJ dislocation. Group A: (The study group) patients were injected with BTX-A in the LPM through an intraoral approach, Group B: (The control group) patients suffering from chronic TMJ dislocation and treated by inter maxillary fixation (IMF).
Results: The study revealed that injecting BTX-A in the LPM prevents the TMJ dislocation and reduced pain caused by the movement of the LPM by 90 % through temporary paralysis of the muscle, thus allowing the muscle to move more naturally.
Conclusions: This is a relatively conservative option, injection into the muscle is straightforward and can be done in outpatients with few complications.
Key words: Temporomandibular joint; Dislocation; Botulinum toxin type A; Lateral pterygoid muscle.