Acute membranous gingivitis: This is trench mouth, a progressive painful infection with ulceration, swelling and sloughing off of dead tissue from the mouth and throat due to the spread of infection from the gums.

Certain germs (including fusiform bacteria and spirochetes) have been thought to be involved, but the full story behind this long- known disease is still not clear.

This condition is also called Vincent's angina after the French physician Henri Vincent (1862-1950). The word "angina" comes from the Latin "angere" meaning "to choke or throttle."

As with most poorly understood diseases, acute membranous gingivitis goes by many other names including acute necrotizing ulcerative gingivitis (ANUG), fusospirillary gingivitis, fusospirillosis, fusospirochetal gingivitis, necrotizing gingivitis, phagedenic gingivitis, ulcerative gingivitis, Vincent's gingivitis, Vincent's infection, and Vincent's stomatitis.