Importance of coronoidotomy and masticatory muscle myotomy in surgical release of trismus caused by submucous fibrosis.

Thirty patients with trismus resulting from betel nut chewing-induced oral submucous fibrosis were treated with either fibrotic tissue release only (group I) or fibrotic tissue release in combination with masticatory muscle myotomy and coronoidotomy (group II). The latter procedures were only performed in patients whose intraoperative interincisal distance remained less than 35 mm immediately after submucous fibrous tissue release. There were eight and 22 patients in groups I and II, respectively. In group I patients, the average intraoperative interincisal distance improved from 19.5 mm to 42 mm. In group II patients, the average intraoperative interincisal distance improved from 13.5 mm to 27 mm after fibrotic tissue release and further improved to 40 mm after masticatory muscle myotomy and coronoidotomy. At an average follow-up of 22.1 months (range, 7 to 70 months), the group I and II patients had an average interincisal distance of 41.5 mm (range, 35 to 50 mm) and 32.9 mm (range, 20 to 42 mm), respectively. These results demonstrate the efficacy of submucous fibrotic tissue release in treating trismus resulting from betel nut chewing-induced submucous fibrosis and confirm the role of additional masticatory muscle and coronoidotomy in treating its severe forms.