Salient virulence factors in anaerobic bacteria, with emphasis on their importance in endodontic infections

Abstract

Endodontic infections by microbial invasion of the necrotic pulp lead to apical periodontitis of both acute and chronic forms. Acute lesions often develop from multiplication of bacteria in primary infections. Such lesions may also occur as exacerbations of chronic forms provoked for example in conjunction with endodontic treatment measures. The clinical course appears related to the character of the microflora. While primary infections are predominated by a mixed flora of anaerobic bacteria and resembles that of aggressive marginal periodontitis, chronic forms of apical periodontitis emerge following regression of the acute infection, whereupon prevailing bacteria have assumed low activity. The significance of virulence factors is easy to understand as far as acute inflammatory conditions are concerned. The role of virulence factors for sustaining chronic inflammation is more unclear and complex. This review is about salient virulence factors in some selected bacterial genera such as Peptostreptococcus, Porphyromonas, Prevotella and Fusobacterium, which often predominate the root canal microbiota in the acute phase of endodontic infections.