Mandibular Dislocation

The condyle becomes locked when it has extended too far forward (in relation to the eminence) and spasm of the pterygoid and masseter muscles prevent it from moving back.

Associated spasm and oedema produce extreme discomfort and anxiety for a patient who can't speak because they are unable to close their mouth.

• Shallow mandibular fossa in the temporal bone
• Weak or torn temporo-mandibular joint (TMJ) ligaments
• Underdeveloped condyle of the mandible
• Connective tissue diseases, e.g. Marfan's syndrome or Ehlers-Danlos syndrome
• Neuroleptic use (orofacial spasm)¹

• Anatomical abnormality of the fossa/interior articular eminence.
• Dislocation can occur bilaterally, or unilaterally, with jaw locked open symmetrically or deviating to one side (opposite to dislocation).
• Palpation shows TMJ anterior to the articular eminence.
• Usually occurs during maximum opening of mouth, e.g. during yawning, laughing, prolonged dental work or an epileptic seizure.
• May also be secondary to trauma.

X-ray of jaw to exclude fracture in dislocation.

Relief of pain and muscle spasm with IV benzodiazepine ± opioid and/or direct injection of local anaesthetic into condylar area.

• Patients should eat a soft diet for one week.
• Avoid wide opening of mouth; place fist under chin when yawning.
• Prescribe analgesics and muscle relaxants. Local heat may offer relief.
• In recurrent cases, two equally efficacious procedures may be used; either eminectomy or siting a miniplate on the articular eminence.^3,4
• Refer to oral or maxillofacial surgeon for follow-up.