Jaw & TMJ Health
Why does my jaw lock up when I open my mouth wide?
17 October 2026 · The Dentist, Al Qusais, Dubai
The short answer
Jaw locking when you open wide is usually caused by the small cartilage disc in your jaw joint (the TMJ) slipping out of its normal position, or by muscle tension and spasm around the joint. It can also come from joint inflammation, teeth grinding, or an uneven bite that puts extra strain on one side. Occasional mild catching isn't an emergency, but frequent locking, pain, or a jaw that gets stuck open or shut needs a proper dental examination.
What's actually happening inside the joint
Your jaw joint, the temporomandibular joint or TMJ, sits just in front of your ear on each side. Between the skull and the lower jawbone there's a small disc of cartilage that acts as a cushion and lets the joint glide smoothly when you chew, talk, or yawn. When that disc shifts slightly out of place, which dentists call disc displacement, the jaw can catch or click as it tries to move past it. Sometimes it pops back with a click and you can keep opening. Other times it genuinely locks, and opening wide becomes painful or impossible until the jaw is coaxed back into position.
A second common cause is muscle related rather than joint related. The muscles that move your jaw, particularly the masseter and temporalis, can go into a kind of spasm after a long day of clenching, stress, or grinding at night. That tightness alone can make wide opening feel restricted, even without anything wrong with the disc itself. The two causes often overlap, which is why TMJ problems can feel confusing and inconsistent from one day to the next.
Why it tends to happen to some people more than others
Grinding or clenching your teeth, especially at night, is one of the biggest drivers. It loads the joint and muscles far more than normal chewing does, and most people who grind have no idea they're doing it until a dentist spots the wear patterns on their teeth. An uneven bite, where your teeth meet unevenly or one side takes more pressure than the other, has a similar effect over time, forcing the jaw to work harder on one side.
Stress is a genuine physical factor here too, not just a vague contributor. It raises muscle tension throughout the jaw and neck, and many patients notice their locking or clicking gets worse during stressful weeks and settles down when things calm. A previous jaw injury, arthritis in the joint, or even a habit of resting your chin on your hand can also play a part. Because there are several possible causes that can look similar from the outside, this is one of those situations where a dentist genuinely needs to examine the joint, feel how it moves, check your bite, and ask about your history before saying what's driving it in your specific case.
What to do about it and when to get it looked at
If the locking is occasional, brief, and not painful, you can reasonably keep an eye on it: avoid very wide yawns, cut down on tough or chewy foods for a while, and notice if stress or tiredness seems to trigger it. If it happens often, if the jaw gets properly stuck open or shut, if there's pain, swelling, or a headache pattern around your temples and ears, or if you've noticed new tooth wear, that's the point to have it assessed rather than wait it out.
At The Dentist in Al Qusais, Dr. Faris Alkhanafseh and Dr. Mohammad Nour examine the joint and bite together, since treating one without the other rarely fixes locking for good. Depending on what they find, treatment might be as simple as a custom night guard to stop grinding, some bite adjustment, or guidance on jaw exercises, with onward referral if a more complex joint issue is involved. New patients get a free first checkup, so if your jaw has been catching or locking lately, book a visit through WhatsApp or at thedentist.ae/book and get a clear answer on what's actually causing it.
This article is general information, not a diagnosis. If you are in Dubai, the free first checkup at our Al Qusais clinic is the fastest way to get an answer about your own teeth.