Trismus
Pronunciation: TRIZ-mus
Reduced or restricted opening of the mouth due to spasm or fibrosis of the muscles of mastication.
Full Definition
In oral medicine, trismus typically refers to any limitation of mouth opening, measured in millimetres of interincisal distance. Normal mouth opening in adults is generally considered to be between 35 and 50 mm; values below 35 mm are often cited as the clinical threshold for trismus, though definitions vary. Trismus may be caused by pericoronitis, post-radiation fibrosis, oral submucous fibrosis, trauma, or temporomandibular joint disorders. Editors should ensure authors specify the cause and measurement method. The term is sometimes confused with 'lockjaw,' which specifically refers to tetanus-associated trismus, a distinction that is clinically and editorially significant.
Usage
Usage note: 'Lockjaw' should not be used as a general synonym for trismus in clinical documents; it specifically denotes tetanus. Authors should state the interincisal measurement when documenting trismus.
In Context
- "Post-radiotherapy trismus was assessed by measuring the interincisal distance at each follow-up visit." — Oncology follow-up report
- "The patient presented with trismus and was found to have pericoronitis around the lower right third molar." — Emergency dental referral letter