I don't have any particular expertise in Middle Ages lore, but I submit that the origin of "trench mouth" given above is in error. Trench mouth, like trench foot as a folk diagnosis originated in the trenches of world war I. High stress, poor diet and hygiene on the front lines may have been responsible for development of severe gingivitis in a significant proportion of the soldiers, although the term today is more commonly applied to "Vincent's Angina" a spirochete and fusiform bacterial co-infection of the oral cavity.