Trismus, also known as lockjaw, is the inability to normally open the mouth due to one of many causes.

Common causes

• Pericoronitis (inflammation of soft tissue around impacted third molar) is the most common cause of trismus.
• Inflammation of muscles of mastication. It is a frequent sequel to surgical removal of mandibular third molars (lower wisdom teeth). The condition is usually resolved on its own in 10-14 days, during which time eating and oral hygiene are compromised. The application of heat (e.g. heat bag extraorally, and warm salt water intraorally) may help, reducing the severity and duration of the condition.
• Peritonsillar abscess, a complication of tonsillitis which usually presents with sore throat, dysphagia, fever, and change in voice.
• Temporomandibular joint disorder (TMD)

Other causes

• Acute osteomyelitis
• Ankylosis of the TMJ (fibrous or bony)
• Condylar fracture or other trauma.
• Gaucher disease which is caused by deficiency of the enzyme glucocerebrosidase.
• Infection
• Local anesthesia
• Needle prick to the medial pterygoid muscle
• Oral submucous fibrosis.
• Radiation therapy to the head and neck.
• A physical side effect of the drug MDMA.
• Tetanus
• Malignant hyperthermia
• Secondary to neuroleptic drug use

Treatment

Treatment requires treating the underlying condition with dental treatments, physical therapy, facial flex, and passive range of motion devices. Additionally, control of symptoms with pain medications (NSAIDs), muscle relaxants, and warm compresses may be used.

References