She Yawned and Her Jaw Would Not Close

Quick answer: A jaw that locks in the open position is a dislocation of the jaw joint. It is alarming but usually straightforward to relocate, and the sooner it is done the easier it is — after a few hours the muscles spasm and it becomes considerably harder.

The call

Sunday morning. Ruth, 57, from Beit Shemesh, had yawned widely at breakfast and her jaw had locked wide open. She could not close it, could not speak clearly, and was drooling because she could not swallow properly.

Her husband phoned. He was calm; she, understandably, was not.

We told them to come straight in and — importantly — not to try forcing it closed on the way.

What we found

She arrived with her mouth held open about 40mm, unable to bring her back teeth together at all. There was a visible hollow in front of each ear where the condyle should have been sitting, and a bulge slightly forward of it. Both sides were dislocated, which is the more common pattern.

This is an anterior dislocation of the temporomandibular joint. The condyle — the rounded top of the lower jaw — has translated forward past the articular eminence, the bony ridge it normally slides up and back over, and the muscles have then contracted and held it there. It is stuck in front of a bump it cannot get back over on its own.

Why it happens. A wide opening is the trigger: yawning, laughing, vomiting, a long dental appointment, biting a very large sandwich. Predisposing factors include a shallow eminence, generalised joint laxity, previous dislocations — after the first, recurrence is much more likely — and certain medications.

Why speed matters. In the first minutes the muscles are stretched but not yet in strong spasm. Within hours the masseter and temporalis clamp down hard, and reduction becomes far more difficult, sometimes needing sedation or a general anaesthetic.

Her first dislocation, about four hours after a previous episode years earlier, had needed sedation in hospital. This one was ninety minutes old.

What we did

Sat her in a low chair with her head supported firmly against the headrest — a solid backstop is essential, since the manoeuvre applies real force.

Standing in front of her, with thumbs wrapped in gauze and placed on the outside of the lower back teeth rather than on top of them (a reflexive bite during reduction can be a serious injury), fingers under the chin.

The movement is downward first, then backward, then upward: press down to free the condyle below the eminence, guide it back, then let it rise into the socket. Steady, sustained pressure rather than force — you are waiting for the muscles to fatigue and release.

It reduced in about forty seconds with an audible clunk, and she closed her mouth immediately.

Afterwards: a supportive bandage for 24 hours, soft diet for a week, ice, anti-inflammatories, and the instruction to support the chin with a hand when yawning.

The outcome

No recurrence in two years. She was referred to a maxillofacial surgeon to discuss options, since recurrent dislocation sometimes warrants surgical management, but with two episodes several years apart the advice was conservative management.

What to do if this happens to you

1. Do not force it closed. You will tighten the muscle spasm and can damage the joint.
2. Do not panic, and do not try to eat or drink.
3. Support the jaw gently with a hand while travelling.
4. Get help within the hour if you can. Speed makes an enormous difference.
5. After it is reduced, do not open wide for a week. Support your chin when yawning.
6. Tell your dentist you have had one. Long appointments then get planned with rest breaks and a bite prop.

Jaw locked open? Do not force it — call Ramat Beit Shemesh Urgent Dental Care immediately: 055-985-8845 · WhatsApp https://wa.me/972559858845 · Harav Kook 28/1, Beit Shemesh.

Based on real cases treated at the clinic. Names have been changed.