Acute necrotizing ulcerative gingivitis (ANUG) is a common, non-contagious infection of the gums with sudden onset. The main features are painful, bleeding gums, and ulceration of inter-dental papillae (the sections of gum between adjacent teeth). This disease, along with necrotizing (ulcerative) periodontitis (NP or NUP) is classified as a necrotizing periodontal disease, one of the seven general types of gum disease caused by inflammation of the gums (periodontitis). The often severe gum pain that characterizes ANUG distinguishes it from the more common chronic periodontitis which is rarely painful. If ANUG is improperly treated or neglected, it may become chronic and/or recurrent. The causative organisms are mostly anaerobic bacteria, particularly Fusobacteriota and spirochete species. Predisposing factors include poor oral hygiene, smoking, poor nutrition, psychological stress, and a weakened immune system. When the attachments of the teeth to the bone are involved, the term NUP is used. Treatment of ANUG is by removal of dead gum tissue and antibiotics (usually metronidazole) in the acute phase, and improving oral hygiene to prevent recurrence. Although the condition has a rapid onset and is debilitating, it usually resolves quickly and does no serious harm. The informal name trench mouth arose during World War I as many soldiers developed the disease, probably because of the poor conditions and extreme psychological stress.
Other signs and symptoms may be present, but not always.
Malaise, fever and/or cervical lymph node enlargement are rare (unlike the typical features of herpetic stomatitis). Pain is fairly well localized to the affected areas. Systemic reactions may be more pronounced in children. Cancrum oris (noma) is a very rare complication, usually in debilitated children. Similar features but with more intense pain may be seen in necrotizing periodontitis in HIV/AIDS.
ANUG may also be associated with diseases in which the immune system is compromised, including HIV/AIDS. ANUG is an opportunistic infection that occurs on a background of impaired local or systemic host defenses. The predisposing factors for ANUG are smoking, psychological stress, malnutrition, and immunosuppression.
The following zones of infection have been described (superficial to deep): the bacterial zone, the neutrophil rich zone, the necrotic zone and the spirochetal zone.
Necrotizing gingivitis is part of a spectrum of disease termed necrotizing periodontal diseases. It is the most minor form of this spectrum, with more advanced stages being termed necrotizing periodontitis, necrotizing stomatitis, and the most extreme, cancrum oris. Acute necrotizing ulcerative gingivitis (ANUG) refers to the clinical onset of NUG. The word acute is used because usually the onset is sudden. Other forms of NUG may be chronic or recurrent.
Necrotizing ulcerative periodontitis (NUP) is where the infection leads to attachment loss, and involves only the gingiva, periodontal ligament and alveolar ligament. Progression of the disease into tissue beyond the mucogingival junction characterizes necrotizing stomatitis.
Treatment includes irrigation and debridement of necrotic areas (areas of dead and/or dying gum tissue), oral hygiene instruction and the uses of mouth rinses and pain medication. If there is systemic involvement, then oral antibiotics may be given, such as metronidazole. As these diseases are often associated with systemic medical issues, proper management of the systemic disorders is appropriate.
Untreated, the infection may lead to rapid destruction of the periodontium and can spread, as necrotizing stomatitis or noma, into neighbouring tissues in the cheeks, lips or the bones of the jaw. As stated, the condition can occur and be especially dangerous in people with weakened immune systems. This progression to noma is possible in malnourished susceptible individuals, with severe disfigurement possible.
In developed countries, this disease occurs mostly in young adults. In developing countries, NUG may occur in children of low socioeconomic status, usually occurring with malnutrition (especially inadequate protein intake) and shortly after the onset of viral infections (e.g. measles).
Predisposing factors include smoking, viral respiratory infections and immune defects, such as in HIV/AIDS. Uncommon, except in lower socioeconomic classes, this typically affects adolescents and young adults, especially in institutions, armed forces, etc., or people with HIV/AIDS. The disease has occurred in epidemic-like patterns, but it is not contagious.
Necrotizing ulcerative gingivitis has been observed for centuries. Xenophon observes sore mouth and foul smelling breath in Greek soldiers in the 4th century BC. Hunter describes the clinical features of ANUG in 1778, differentiating it from scurvy (avitaminosis C) and chronic periodontitis. Jean Hyacinthe Vincent, a French physician working at the Paris Pasteur Institute describes a fusospirochetal infection of the pharynx and palatine tonsils, causing "ulcero-membranous pharyngitis and tonsillitis", which later became known as Vincent's angina. Later in 1904, Vincent describes the same pathogenic organisms in "ulceronecrotic gingivitis". Vincent's angina is sometimes confused with NUG, however the former is tonsillitis and pharyngitis, and the latter involves the gums, and usually the two conditions occur in isolation from each other.
The term trench mouth evolved because the disease was observed in front line soldiers during World War I, thought to be a result at least partly because of extreme psychologic stress they were exposed to. The same condition was appearing in civilians during periods of bombing raids, who were away from the front line, and who had relatively good diets during wartime due to rationing, so it is assumed that psychologic stress was the significant causative factor. It has also been associated with high tobacco use in the army.
Many other historical names for this condition (and Vincent's angina) have occurred, including: "acute membranous gingivitis", "fusospirillary gingivitis", " fusospirillosis", "fusospirochetal gingivitis", "phagedenic gingivitis", "Vincent stomatitis", "Vincent gingivitis", and "Vincent infection".
In the late 1980s-early 1990s, it was originally thought that some necrotizing periodontal diseases seen in severely affected AIDS patients were strictly a sequela of HIV, and it was even called HIV-associated periodontitis. It is now understood that its association with HIV/AIDS was due to the immunocompromised status of such patients; it also occurs with higher prevalence in association with other diseases in which the immune system is compromised.