Dislocated jaw: what to do if your mouth is stuck open, and why not to put it back yourself

The jaw joint lies just in front of the ear, where the rounded head of the lower jaw (the condyle) sits in a hollow in the temporal bone. When you open your mouth wide, the head of the joint does not just rotate; it also slides forward and rides up onto the bony bump in front of it (the articular eminence). As MSD Manuals describes it, in an anterior dislocation the head of the joint passes in front of this bump and gets caught there. The moment it catches, the muscles that close the jaw tighten and go into spasm, and this spasm stops the head of the joint from going back. That is why the mouth stays open.

The typical story of a dislocation is a familiar one: MSD writes that the moment it starts is usually a wide opening followed by biting pressure, for example biting into a big sandwich with crusty bread, yawning very widely or keeping the mouth open for a long time during dental treatment. In its version for patients, it also lists being sick. Rarely, it can happen with a blow. Dislocation that happens on its own is mostly seen in people who have dislocated before; MSD notes that these people may naturally have loose joint ligaments, and that joint laxity may be associated with jaw joint disorders.

A dislocation is not hard to recognise. MSD writes that the person's mouth is stuck wide open and they cannot close it, and that the pain gets worse the more they try to close it. According to MSD, dislocations that happen on their own are often on both sides; in this case the jaw looks as if it is jutting forward. If the centre line of the lower jaw has shifted to one side, the dislocation is on one side. Speaking, swallowing and holding in saliva can become difficult. In the hollow in front of the ear, a gap may be felt where the head of the joint should be.

A dislocation should not be confused with locking, in which the mouth stays shut and will not open. With locking, the mouth is closed and will not open; the cause is usually the disc inside the joint slipping forward and blocking the opening. With a dislocation, the mouth is open and will not close. The two are managed quite differently: locking does not need A&E, but because MSD writes that early treatment clearly improves the outcome, it needs to be seen by a dentist or a jaw surgeon within a few days, whereas a dislocation has to be put back the same day. The details of closed locking are on our page about clicking and locking in the jaw joint.

MSD states clearly why time matters: the longer the jaw stays dislocated, the harder it is to put back and the more likely the dislocation is to recur. When a dislocation lasts longer than a few hours, a sedative or a numbing injection into the joint may be needed for the muscles to relax. When the records of patients who came to a trauma centre in Brazil with a dislocation were examined, the average time between the dislocation and a specialist examination was 30.69 hours, and the longer the dislocation had lasted, the more likely it was that it had to be put back under intravenous sedation. In the same study, recurrent dislocation was more common in older patients.

Why trying to close the jaw at home does not work lies in the logic of the correct manoeuvre. The key phrase in MSD's description of the reduction is this: first down, then back. The clinician places their thumbs behind the lower molars or on the bony ridge outside them and pushes the back of the jaw down with steady, firm force, and once the head of the joint has been pulled down far enough to pass under the bump, guides the jaw backwards. The mistake made at home is to force the mouth shut without first bringing the back of the jaw down: as long as the head of the joint stays caught in front of the bump, the effort to close it increases the muscle spasm and the pain. In MSD's description, upward force on the chin only works while firm, continuous downward force is being applied to the back teeth and the patient is completely relaxed. What is more, MSD stresses that when the head of the joint goes back into place, the jaw snaps shut with the force of the tensed muscles, putting both the patient's tongue and the fingers of whoever is doing the manoeuvre at risk of being bitten.

Dislocation after a blow is a separate category. MSD counts a fracture accompanying the dislocation as an absolute barrier to putting it back by hand; it writes that dislocations sideways, inwards, upwards or backwards, rather than forwards, should also be managed by oral and maxillofacial surgery, and it calls for a CT scan when the dislocation is due to trauma. Among the rare complications of reduction are a fracture of the lower jaw and displacement of an existing fracture; MSD adds that a lower jaw fracture is sometimes only noticed when the pain does not go away after the reduction. So no manoeuvre should be tried at home on someone whose mouth will not close after a fall, an accident or a punch.

A dislocated jaw is always a condition that needs to be assessed the same day; even the situations in the first list are not for waiting at home. The situations in the second list carry additional risk, so they call for acting without waiting and without trying anything at home.

The sequence below also shows why it should not be tried at home: the success of the manoeuvre depends on the patient relaxing, on force being applied in the right direction and on a fracture being ruled out.

1. 1

   History and ruling out a fracture

   You are asked how the dislocation happened, whether there was a blow and whether you have dislocated before. MSD advises that an X-ray is not always needed in a patient with no blow who has dislocated before, whereas a CT scan should be taken when the dislocation is due to trauma.

2. 2

   Calming the patient

   MSD stresses that anxiety should be eased and cooperation obtained before the manoeuvre: the jaw should be left relaxed, with the head resting against the headrest. If the patient cannot relax, a sedative or a numbing injection into the joint can be used; however, most dislocations are put back without them.

3. 3

   First down, then back

   Wearing gloves, and with their thumbs wrapped in gauze, the clinician places their thumbs on the lower molars or on the bony ridge outside them and curls their other fingers under the jaw. They push the back of the jaw down with steady force so that the head of the joint passes under the bump, then guide the jaw backwards. At this point the jaw usually slips back into place by itself.

4. 4

   Checking it has worked

   MSD writes that a successful reduction is recognised by the mouth being able to close, while the muscle pain lasts for a while. The patient is asked to check whether the teeth meet normally by opening and closing gently, and is told not to open wide to test it.

5. 5

   The next step if the attempt fails

   MSD notes that repeated failed attempts can worsen the muscle spasm, and that in some patients the reduction has to be done under deep sedation or general anaesthetic. Failed attempts at home can have the same effect.

6. 6

   Discharge instructions

   You are given moist heat, a painkiller if needed, soft food in small mouthfuls, the advice to put your fist under your chin when yawning, and sometimes a figure-of-eight bandage wrapped from under the jaw over the top of the head (a Barton bandage) for 2 to 3 days.

A single dislocation is usually dealt with by putting it back and a few weeks of care. If the dislocation recurs, simple measures are discussed first, then injection treatments around the joint, and surgery last of all.

The following are habits that make a dislocation harder to put back, raise the risk of it happening again or lead to injury.

The sequence below is for a single anterior dislocation put back by hand. With a recurrent dislocation or one due to trauma, the plan of the clinician treating you comes first.

1. The first few hours

   The mouth can close, but pain and fatigue in the jaw muscles continue. MSD recommends moist heat and, if needed, a painkiller such as ibuprofen.

2. The first 2 to 3 days

   If the clinician thinks it necessary, a bandage wrapped from under the jaw over the top of the head limits how wide the mouth can open. MSD writes that the bandage can be uncomfortable and make eating and drinking difficult, so sticking with it can be hard.

3. 4 to 6 weeks

   Avoid opening your mouth wide, put your fist under your chin when yawning, and eat soft food in small mouthfuls. MSD stresses that avoiding opening wide for at least 6 weeks is the most important step. During this time, put off planned dental treatment if possible, or keep it short.

4. Afterwards

   If the dislocation does not recur, normal life resumes. If it does recur, injection or surgical options should be discussed with an oral and maxillofacial surgeon.

A single dislocation is usually put back at A&E with a manoeuvre lasting minutes; what widens the scope is how long the dislocation has lasted, an accompanying fracture and recurrence. These are the items that determine it:

How long the dislocation has lasted

A short-lived dislocation is usually put back without medicine; a dislocation lasting hours may need sedation or a general anaesthetic.

Imaging

A CT scan for a dislocation after a blow, and a panoramic X-ray when the diagnosis is in doubt, are separate items.

Recurrence

A single dislocation, and the injection or surgical treatment done for recurrent dislocation, are very different scopes.

An accompanying joint problem

If there is joint laxity or a jaw joint disorder, it needs to be assessed and monitored separately.