11.3.2 Necrotizing ulcerative gingivitis
Necrotizing ulcerative gingivitis (NUG) is one of the commonest acute diseases of the
gingiva. In the United States and Europe, NUG affects young adults in the 16-30 age
range with reported incidence figures of 0.7-7%. In developing countries, NUG is
prevalent in children as young as 1 or 2 years of age when the infection can be very
aggressive leading to extensive destruction of soft and hard tissues (609HFig. 11.3).
Epidemic-like occurrences of NUG have been reported in groups such as army
recruits and first-year college students. These outbreaks are more likely to be a
consequence of the prevalence of common pre-disposing factors rather than
communicability of infection between subjects.
Clinical features
NUG is characterized by necrosis and ulceration, which first affect the interdental
papillae and then spread to the labial and lingual marginal gingiva. The ulcers are
'punched out', covered by a yellowish-grey pseudomembranous slough, and extremely
painful to the touch (610HFig. 11.3). The acute exacerbation is often superimposed upon a
pre-existing gingivitis, and the tissues bleed profusely on gentle probing. The standard
of oral hygiene is usually very poor. A distinctive halitosis is common in established
cases of NUG, although fever and lymphadenopathy are less common than in herpetic
gingivostomatitis.
The clinical course of NUG is such that the acute stage enters a chronic phase of
remission after 5-7 days. Recurrence of the acute condition is inevitable, however,
and if this acute-chronic cycle is allowed to continue then the marginal tissues lose
their contour and appear rounded. Eventually, the inflammation and necrosis involve
the alveolar crest and the subsequent necrotizing periodontitis leads to rapid bone
resorption and gingival recession. Progressive changes are also a consequence of
inadequate or incomplete treatment.
Aetiology
A smear taken from an area of necrosis or the surface of an ulcer will reveal numerous
dead cells, polymorphonuclear leucocytes, and a sample of the micro-organisms that
are frequently associated with NUG. Fusiform bacteria and spirochaetes are both
numerous and easy to detect. A fusospirochaetal complex has been strongly
implicated as the causative organisms in NUG. Other Gram-negative anaerobic
organisms including Porphyromonas gingivalis, Veillonella species, and Selenomonas
species have been detected, which suggests that NUG could be a broad anaerobic
infection.
A viral aetiology has also been suggested, primarily because of the similarity between
NUG and known viral diseases. The restriction of the disease to children and young
adults, for example, may infer that older subjects have undergone seroconversion (and
are thus immune) as a consequence of clinical or subclinical viral infection in earlier
life. The recurring episodes of the disease may also be explained by a viral
hypothesis. The ability to undergo latent infection that is subject to reactivation is a
characteristic of the herpesvirus. The argument for the implication of a virus in NUG