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.