Microorganisms involved in endodontic infection of permanent teeth: A systematic review

This study investigated the microbial species present in necrotic pulps of permanent teeth needing endodontic treatment. The search for articles was conducted on the Health Science Database and considered all articles published until October 2011, with selected human clinical studies examined, through molecular biology the microorganisms that are present in root canals of permanent teeth requiring root canal treatment with necrosis pulps (exposition). The selected articles were categorized according to the methodological quality and evidence in levels A (high), B (moderate), and C (low). The search strategy was based on PubMed, Bireme, Cochrane and OVID databases. The data extracted from the studies were also tabulated. Eighty-four titles and abstracts were assessed and eight articles met the inclusion criteria, showing that there is a high diversity of microorganisms involved in necrotic permanent teeth. The microorganisms found in these articles were: Porphyromonas gingivalis (27.8%), Porphyromonas endodontalis(42.6%), Prevotella intermedia (5.6%), Prevotella nigrescens (7.4%), Bacteroides forsythus (21%) and Enterococcus faecalis (>50%). This systematic review found high evidence of the polymicrobial nature of primary endodontic infections in necrotic permanent teeth, and also showed that there is a dominance of anaerobic bacteria.   Key words: Microorganisms, endodontic infection, root canal.