Apical periodontitis is a sequela of endodontic infection, which manifests as a host defense response to the microbial challenge emanating from the root canals. To achieve an optimal outcome, microorganisms must be eliminated or reduced to levels that allow healing of the periradicular tissue.
Objective: To analyze the literature on microorganisms, such as Enterococcus faecalis, Fusobacterium nucleatum, Candida albicans, Epstein-Barr, which are important in persistent apical periodontitis.
Methodology: Articles on the subject published through PubMed, SCOPUS and Google Scholar databases were analyzed, with emphasis on the last 5 years. It was performed with the words "Enterococcus faecalis", "Fusobacterium nucleatum", "Candida albicans", "Epstein-Barr", "Herpesviridae", "Root canals", "Persistent apical periodontitis".
Results: E. faecalis involved in persistent apical periodontitis because of its adaptability to extreme environments, growing in alkaline pH and using periodontal ligament fluids as nutrients. Lysed Fusobacterium nucleatum cells could potentially increase the severity of persistent apical periodontitis. Candida albicans is one of the dominant pathogens in persistent apical periodontitis because of its membrane protein Msb2. Epistein-Barr virus may be implicated in the pathogenesis of apical periodontitis by direct cytopathic action on infected cells, however, its replication in persistent apical periodontitis is still unclear.
Conclusions: The microbiota of teeth with persistent apical periodontitis, presents a mixed and complex profile, it is important to know the role of these microorganisms, because microbial persistence, seems to be the most important factor in root canal treatment failure.