Jaw dislocation: the mouth stuck open
- Emergency
After a big yawn or a long dental visit the jaw can lock open with the condyles in front of the joint. It can usually be reduced at the bedside.
See it in 3D: TMJ disc · TMJ capsule · Lateral pterygoid · Mandible
What it is
In anterior dislocation of the mandible, the condyle slides in front of the articular eminence and the muscles of mastication spasm, locking it there. The patient cannot close the mouth, the chin juts forward (or to one side if only one joint is dislocated), speech is difficult and drooling is common. Triggers are yawning, laughing, vomiting, dental treatment, intubation and seizures; some drugs (antipsychotics and antiemetics causing dystonia) can cause it. A blow to the jaw can also fracture the condyle, which must be excluded when there is trauma.
How to recognise it
- Mouth stuck open, unable to close, chin forward, hollow in front of the ear.
- Unilateral: chin deviates to the opposite side.
- Trauma or atypical history: radiograph or CT before reduction to exclude fracture.
- Drug-induced dystonia can mimic or cause it and is treated differently.
- Recurrent dislocation needs dental or surgical review.
What to do at once
- Exclude fracture if there was trauma; consider dystonia if on antipsychotics or antiemetics.
- Explain, sit the patient upright with the head supported; analgesia or light sedation if needed.
- Facing the patient, place gauze-wrapped thumbs on the lower molars (or outside on the external oblique ridges) and the fingers under the jaw.
- Press firmly down and then back to bring the condyles below and behind the eminence; then let the jaw close.
- After reduction, check the bite and advise limited opening (supporting the chin when yawning) and soft diet for some days.
Costly mistakes
- Thumbs on the molars without protection can be bitten when the jaw snaps shut.
- Missing a condylar fracture in trauma leads to malocclusion and joint damage.
- Prolonged dislocation (days) is harder to reduce and may need general anaesthesia.
Next step / Initial management
- Successful reduction: soft diet, limit opening, and refer to the dentist or maxillofacial surgeon if it recurs.
- Failed reduction or associated fracture: refer to maxillofacial surgery the same day.
- Drug-induced dystonia: stop the culprit and treat with an anticholinergic as per protocol, and review the medicines.
Test yourself
Think of the answer, then tap the question to see it.
How does a unilateral mandibular dislocation present?
The mouth is open and the chin deviates to the side opposite the dislocated joint.
In which direction is force applied to reduce an anterior TMJ dislocation?
Downwards and then backwards, to bring the condyle below and behind the articular eminence.
What must be excluded before reducing a dislocation after trauma?
A fracture of the mandibular condyle.
Connections
See it in 3D4
The structures of Durgical's 3D anatomy where it is found.
Educational content; it does not replace assessment by a dentist or doctor and is not a clinical instruction. For facial or neck swelling with difficulty swallowing or breathing, a knocked-out tooth or bleeding that will not stop, go to an emergency department at once.
Sources: Mandible Dislocation (StatPearls Publishing (NCBI Bookshelf), 2023); Anatomy, Head and Neck, Temporomandibular Joint (StatPearls Publishing (NCBI Bookshelf), 2025); Mandible Fracture (StatPearls Publishing (NCBI Bookshelf), 2023).
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Representative model, for educational purposes only.