Trismus is the reduced opening of the jaws. It is usually related to the spasm of the jaw muscles.

Lockjaw can be painful. In some cases, it results in complications.


  1. Anamnesis: Date and circumstances of occurrence- Evolution- Antecedent- Tetanus vaccination
  2. Clinical examination:
    1. Extraoral exam:

Warning signs: Pain- Swelling of the face- General signs- dysphagia- Dysphonia

Range of the mouth opening= 47+/-7mm

Evaluation of the severity of the trismus:

    -Slight trismus: The mouth opening is between 20 and 40 mm

     -Moderate trismus: Between 10 and 20 mm

     -Severe trismus: Less than 10 mm

Visual examination of the face: Swelling- bruise- wound- asymmetry

Palpation of the temporo-mandibular joints, muscles, bones, lymph nodes: Muscle spasm- sensitivity- adenopathy

2. Intraoral exam: Teeth- mucosa- tonsils- soft palate- oropharynx (to diagnose nasopharyngeal carcinoma)

  • X-ray: Dental panoramic- scan- cone beam
  • Differential diagnosis: 

-Permanent constriction of the jaws

-Fake trismus:

For legal or psychiatric reasons, trismus is simulated by the patient.

If fake trismus is suspected, inducing the gag reflex with a tongue depressor can confirm the diagnosis.


1. Local:

-Infection: Dental ( pericoronitis- cellulitis)- bone ( osteitis- osteoradionecrosis)- mucosa ( stomatitis ..)- salivary

-Trauma: Fracture of facial bones- contusion of the temporomandibular joints- contusion of the masticatory muscles

-Function: Dysfunction of the manducation apparatus- dental occlusion disorder- mental disorder


-Iatrogenic: Fracture of the mandibular angle while extracting the wisdom tooth- radiation therapy

2. Systemic:


The announcing symptom of this infection is lockjaw.

The spasms begin in the jaw muscles making it hard to open the mouth, swallow, talk, etc.


Some medications can lead to drug intoxication: Neuroleptics- antiulcer- antiemetic.

-Dietary deficiency:

Hypocalcemia ( tetany)- vitamin B1 deficiency- hypoglycemia.

-Neurologic: Stroke.


  1. Causal treatment: Drainage of the pus- fracture immobilization- restore a normal occlusion- tumor removal.
  2. Rehabilitation: Massage- thermotherapy- mobilizing devices.


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