TRISMUS : Aetiology, Differential Diagnosis and Treatment

Trismus is a problem commonly encountered by the dental practitioner. It has a number of potential causes, and its treatment will depend on the cause. 

This article discusses the primary causes of this condition and the various treatments available.


Trismus is an inability to open the mouth. According to Dorland’s Illustrated Medical Dictionary trismus (Greek Trimos: ‘grating’, ‘grinding’) is : a motor disturbance of the trigeminal nerve, especially spasm of the masticatory muscles, with difficulty in opening the mouth, a characteristic early symptom of tetanus. 

Trismus has a number of potential causes, which range from the simple and non-progressive to those that are potentially life-threatening. Kazanjian divided ankylosis of the temporomandibular joint into true and false. 

The true type of ankylosis was attributed to pathological conditions of the joint, and false ankylosis was applied to restrictions of movement resulting from extra-articular joint abnormalities. 

This latter type of ankylosis is what most clinicians know as trismus. In a busy practice, it is not unusual to see several patients each month with a complaint of trismus. 

This condition may impair eating, impede oral hygiene, restrict access for dental procedures and adversely affect speech and facial appearance.