What it is
An inability to fully open or close the jaw, caused by disc displacement or muscle spasm in the temporomandibular joint.
An inability to fully open or close the jaw, caused by disc displacement or muscle spasm in the temporomandibular joint.

At a glance
What it is
An inability to fully open or close the jaw, caused by disc displacement or muscle spasm in the temporomandibular joint.
Commonly experienced as
Evidence context
Emerging evidenceSee the evidence snapshotContext
Locking jaw (trismus or TMJ locking) describes a condition in which the jaw becomes stuck — either in a partially open position that cannot be fully closed (open lock, from anterior disc displacement without reduction) or with severely restricted opening from acute muscle spasm (trismus). TMJ locking from disc displacement occurs when the articular disc within the temporomandibular joint displaces and becomes lodged, mechanically blocking movement. Trismus — severe restriction of jaw opening — arises from masseter muscle spasm (due to bruxism or TMD), acute dental infection, pericoronitis (impacted wisdom tooth inflammation), or rarely from more serious causes including abscess, tetanus, or nasopharyngeal malignancy. Any acute inability to open or close the jaw warrants dental or medical assessment to identify the cause.
The Evidence
What research and clinical practice say about jaw locking, its causes, and the approaches used to manage it.
Jaw locking has identifiable causes and evidence-supported care pathways
TMJ locking and trismus are well-characterised conditions with moderate-to-strong evidence supporting physiotherapy, splinting, and in some cases minor procedures. Identifying the underlying cause is essential before any management approach is chosen.
Jaw locking caused by dental abscess, pericoronitis, or spreading infection can worsen rapidly without professional care. Trismus following trauma, or accompanied by fever, swelling, or difficulty swallowing, warrants same-day assessment. Tetanus and nasopharyngeal malignancy are rare but serious causes that must be excluded by a qualified clinician.
Physiotherapy — including manual therapy and targeted jaw exercises — has moderate-to-good evidence for managing TMJ disc displacement. Occlusal splints carry moderate evidence for reducing muscle-driven restriction. Arthrocentesis (joint irrigation) is supported for cases that do not respond to conservative care. Evidence for complementary approaches is limited and generally adjunctive.
Open lock from anterior disc displacement leaves the jaw stuck partially open and unable to close. Trismus — severe restriction of opening — typically arises from masseter spasm, bruxism, or acute infection. Distinguishing between these presentations matters because management differs significantly. A dental or orofacial specialist assessment is the appropriate starting point.
Physiotherapy, occlusal splinting, and pain support form the core of conservative care. Acute infection-related trismus requires dental treatment of the underlying cause. Stress-related bruxism may benefit from behavioural strategies alongside dental support. Complementary approaches such as acupuncture or massage are sometimes used alongside conventional care, though evidence for these specifically in jaw locking is limited.
A dentist or oral and maxillofacial specialist is the primary referral for most cases of jaw locking. Orofacial physiotherapists are well-placed to manage TMJ disc displacement and muscle-related restriction. If infection is suspected, prompt dental or medical review is needed. Persistent or unexplained jaw restriction should always be assessed professionally before exploring complementary options.
Gyfts provides educational context to help you understand jaw locking and the landscape of available approaches. It does not assess your individual situation, identify the cause of your symptoms, or recommend a specific course of action. If your jaw has locked suddenly, is worsening, or is accompanied by other symptoms, please seek professional assessment promptly.
Featured
These practitioners have chosen to be featured on Gyfts.
Read next
References
Educational sources that inform this overview. Inclusion is for context and does not imply endorsement.
Full citations are maintained by the Gyfts editorial team and reviewed periodically.
Keep exploring
Browse verified practitioners, explore honest overviews, and take what you learn to a conversation — at your own pace.