Jaw Lock – Part 2: Understanding Sudden Jaw Locking: “Open Lock”

Most people think of “jaw lock” as the jaw getting stuck closed. But the jaw can also lock in the open position, making it difficult or impossible to close the mouth. This is often called an open lock.

Open lock can feel scary because it may happen suddenly while yawning, laughing, eating, vomiting, or during a dental procedure. In some cases, the jaw joint has moved too far forward and cannot glide back into its normal position without help.

Open lock may be classified into subluxation and dislocation.

Subluxation is a self-reducing partial displacement of the mandibular condyle beyond its normal functional range, often presenting as transient open locking or a sensation that the jaw “goes out and comes back.”

Dislocation, also called luxation, is a complete displacement of the mandibular condyle anterior to the articular eminence, where the patient is unable to close the mouth without assisted reduction.

Clinically, subluxation is usually brief and self-limiting, while true dislocation is more urgent and requires prompt evaluation and management because the mouth/ jaw may remain stuck open and may be painful.

What does open lock feel like?

A patient with open lock may notice:

• The mouth is stuck open and cannot close normally.

• The jaw may look shifted to one side.

• There may be pain in front of the ear or around the TMJ.

• Speech, swallowing, and chewing may be difficult.

• Drooling may occur because the mouth cannot close.

• The bite may suddenly feel “off” after the jaw unlocks or is reduced.

• TMJ disorders can cause pain, stiffness, clicking, popping, limited motion, and locking of the jaw.

  
  

Understanding Open Lock: This illustration contrasts subluxation and dislocation of the jaw. In subluxation, the jaw can move forward and then return to its normal position, whereas dislocation results in the jaw being stuck open, potentially needing medical treatment. Common causes include yawning, laughing, taking large bites, vomiting, or lengthy dental procedures.

Why does open lock happen?

The temporomandibular joint, or TMJ, is not just a hinge. It also slides forward when you open your mouth wide. In open lock, the lower jaw may move too far forward and become temporarily trapped in front of the joint’s normal stopping point.

Common triggers include:

• Yawning widely.

• Taking a large bite of food.

• Laughing or singing with the mouth wide open.

• Dental procedures that require prolonged opening.

• Vomiting.

• Joint laxity or hypermobility especially patients with Ehlers- Danlos Syndrome

• Prior history of jaw locking or dislocation.

• Clenching, muscle guarding, or underlying TMJ dysfunction.

Open lock vs. closed lock

These are different problems.

• Closed lock usually means the jaw cannot open fully. This is often associated with disc displacement without reduction, where the TMJ disc blocks normal opening.

  
  

• Open lock means the jaw is stuck open and the patient cannot close normally. This may represent a TMJ subluxation or dislocation.

Both can be painful, but open lock is more urgent when the jaw remains stuck open.

What should you do if your jaw gets stuck open?

If the jaw is truly stuck open, seek urgent care from a dentist, oral surgeon, emergency department, or clinician trained in TMJ reduction. Do not force the jaw to close. Do not keep repeatedly opening and closing to “test it.”

A dislocated jaw usually needs prompt attention, and successful reduction restores the ability to close the mouth, although soreness and muscle spasm may continue afterward.

Seek emergency care immediately if there was trauma, severe pain, swelling, inability to swallow, breathing difficulty, fever, neurologic symptoms, or if the jaw remains locked open.

What happens after the jaw unlocks?

Even after the jaw goes back into place, the joint and muscles may remain irritated. Patients may have soreness, fear of opening, muscle spasm, bite changes, or recurrent locking.

After an open lock episode, evaluation may include:

• TMJ and muscle examination.

• Measurement of jaw opening and jaw movement pattern.

• Bite evaluation.

• Assessment for joint hypermobility or instability.

• Imaging when needed, such as CBCT, MRI, or other studies depending on the suspected cause.

How is recurrent open lock treated?

Treatment depends on the cause and frequency of locking.

Options may include:

• Education on avoiding extreme mouth opening.

• Soft diet temporarily after an episode.

• Moist heat or ice depending on timing and symptoms.

• Anti-inflammatory or muscle-relaxing medications when appropriate.

• Physical therapy or guided jaw control exercises.

• TMJ stabilization appliance in selected cases.

• Management of clenching, bruxism, posture, and muscle overactivity.

• Injections or minimally invasive procedures such as Prolotherapy in selected recurrent cases.

• TMJ Surgery when dislocations are frequent, prolonged, traumatic, or not responding to conservative care.

For many TMD problems, conservative and reversible treatments are usually considered first. NIDCR notes that TMDs can involve the joint, muscles, and supporting tissues and may cause jaw pain, stiffness, limited movement, or locking.

Treatment for Open jaw Locks : Subluxation and Dislocation

Surgery for Open locks (subluxation and dislocation) are rarely the first- line of treatment , but it may be considered when the jaw repeatedly dislocates, does not respond to conservative care, or significantly affects eating, speaking, dental care, or quality of life. Surgical options generally fall into three categories:

• Minimally invasive TMJ procedures, such as arthrocentesis or arthroscopy;

• Procedures that limit excessive jaw movement, which help prevent the condyle from slipping too far forward

• Procedures that help the jaw return to position, such as eminectomy, where the bony pathway is modified so the jaw can glide back more easily. The correct option depends on whether the condition is subluxation or true dislocation, how often it occurs, imaging findings, pain level, and overall joint stability.

How can you reduce the risk of another open lock?

• Patients with a history of open lock should avoid opening the mouth extremely wide.

• Support the jaw when yawning by placing a fist or fingers gently under the chin.

• Cut food into smaller pieces. Avoid large sandwiches, prolonged dental opening without breaks, nail biting, gum chewing, and other habits that overload the jaw.

• For dental visits, tell your dentist that you have a history of open lock. Bite blocks, shorter appointments, frequent breaks, and jaw support may help reduce risk.

When should you see an Orofacial pain specialist?

You should be evaluated if:

• Your jaw has locked open even once.

• The jaw repeatedly feels like it may “go out.”

• You have painful clicking or popping with locking.

• Your bite feels different after a locking episode.

• You have jaw pain, headaches, facial pain, or neck pain with jaw dysfunction.

• You are avoiding yawning, eating, or dental care because of fear of locking.

Open lock can be alarming, but the right diagnosis can help determine whether the problem is joint hypermobility, muscle guarding, disc-condyle coordination, dislocation tendency, or another TMJ-related condition.

Advanced TMJ Maxillofacial Pain & Sleep Center evaluates jaw locking, TMJ pain, facial pain, headaches, and sleep-related jaw concerns. If your jaw locks open or feels unstable, an evaluation can help identify the cause and prevent repeated episodes.