BLACK-PIGMENTED GRAM-NEGATIVE ANAEROBES IN ENDODONTIC INFECTIONS

Necrotic dental root canal infections are polymicrobial infections dom inated by anaerobic bacteria. The number of different species in one c anal is usually low, approx. 4-7 species. The species isolated most fr equently belong to the genera Prevotella, Porphyromonas, Fusobacterium , Peptostreptococcus, Eubacterium and Streptococcus. The frequency of isolation of black-pigmented Gram-negative anaerobes in endodontic inf ections varies from 25% to > 50%. Pr. intermedia is the most commonly found pigmented species, followed by Pr. denticola and two Porphyromon as species, P. gingivalis and P. endodontalis. Several studies have sh own that P. gingivalis and P. endodontalis are closely related to the presence of acute symptoms in endodontic infections, whereas other bla ck-pigmented Gram-negative anaerobes are not. However, several other s pecies may also be involved in acute infections. Moreover, Porphyromon as species have occasionally been isolated from cases with no symptoms . Although Porphyromonas spp. are clearly related to symptoms at the b eginning of therapy, they are not important for the prognosis of the t reatment.