an acute or recurrent gingivitis of young and middle-aged adults characterized clinically by gingival erythema and pain, fetid odor, necrosis, and sloughing of interdental papillae and marginal gingiva that gives rise to a gray pseudomembrane; fever, regional lymphadenopathy, and other systemic manifestations also may be present. A fusiform bacillus and Treponema vincentii can be isolated from the gingival tissues in large numbers and are thought to play a significant but poorly defined role in the pathogenesis. SYN: fusospirochetal gingivitis, trench mouth, ulceromembranous gingivitis, Vincent disease, Vincent infection.