Prolonged Limitation of Mouth Opening (Trismus)
This can be due to medial pterygoid contracture / spasm.

This spasm may be the result of injury of the
medial pterygoid muscle caused by a
needle (repeated injections during
Inferior Alveolar Nerve block) or by trauma of
the surgical field especially when difficult lengthy surgical procedures are
performed.  Other causative factors are gross infection, inflammation of the post-
extraction wound,
hæmatoma (blood clot) and post-operative œdema (swelling).
The management of trismus depends on the cause.  Most cases do not require
any particular therapy.  When acute inflammation or a
hæmatoma is the cause of
trismus, hot mouth rinses are recommended initially and then broad-spectrum
antibiotics are administered.

Other supplementary therapeutic measures include:

  • Heat therapy, i.e., hot compresses are placed extra-orally for approximately
    20 min every hour until symptoms subside.

  • Gentle massage of the TMJ area.

  • Administration of painkillers, anti-inflammatory and muscle relaxant (such as
    sedatives) medication.

  • Physiotherapy lasting 3 – 5 min every 3 – 4 hours, which includes movements
    of opening and closing the mouth, as well as lateral movements, aimed at
    increasing the extent of mouth opening.

  • Administration of sedatives for management of stress which worsens while
    trismus persists, leading to an increase of muscle spasm in the area
Photos showing a patient with
Trismus and the Use of
Spatulas to Ameliorate the
Last Updated 20th March 2015
Useful Articles:

Dental Update 2002. Trismus - Aetiology, Differential Diagnosis and Treatment

Br J Oral Maxillofac Surg 2005.  Possible Link between Extraction of Wisdom
Teeth & Temporomandibular Disc Displacement with Reduction

J Oral Maxillofac Surg 2005.  Limited Painful Mouth Opening

Br J Oral Maxillofac Surg 2010.  Technical note.  Battling trismus - the “Pat-Bite”

Br J Oral Maxillofac Surg 2011.  Reliability & validity of a new method of nurse-led
assessment of trismus
Photos showing a patient with
Trismus and the Use of
Spatulas to Ameliorate the
Photo showing a patient with Trismus using a Trismus Screw.  These have to be
used with caution as they can severely traumatised the 'front' teeth and may lead
to their
Causes of Trismus:

Acute Trismus


•        Pericoronitis
•        Odontogenic Infection with spread involving masticatory (chewing) muscles,
TMJ (jaw joint), bone or fascial spaces (Ludwig’s Angina)
•        TMJ / bone infections
•        Tonsillar / pharyngeal infections
•        Parotitis (parotid salivary gland infection)
•        Otitis (ear infection)
•        Tetanus (“Lock jaw” 2nd to
C tetani infection)


•        Jaws
•        Facial soft tissues


•        3rd Molars (“wisdom tooth”) removal
•        Other jaw & oral surgery
•        Associated with
hæmatoma (blood clot)
•        Local anæsthetic injection trauma to
pterygoid (chewing) muscles


•        Ecstasy

Malignant Hyperthermia (explanation)

TMJ Disease (eg gout, Rheumatoid Arthritis) & pain-dysfunction syndrome

Sub-Acute Trismus

•        Tumour infiltration of muscles / TM joint
•        Chronic infection

Chronic Trismus

•        Soft tissue scar formation or TMJ damage
Sub-mucous Fibrosis
•        Scleroderma
•        TMJ Ankylosis (explanation)
•        Masticatory Muscular disorders (eg myotonia,
myositis ossificans,
fibro-dysplasia ossificans)
•        Supra-bulbar palsy