Comparative analysis of microbial presence in root canals

Objectives: To detect certain 8 microorganisms in the root canals of teeth suffering from endodontic interappointment flare-ups compared with those in the root canals of chronic apical periodontitis, and to investigate the combinations of bacteria found in flare-up cases. Methods: Clinical samples were collected from 26 teeth suffering from endodontic flare-ups after canal preparation and 23 infected teeth associated with chronic apical periodontitis. A 16S rRNA-based polymerase chain reaction(PCR) detection method was used in this study to identify 8 relative bacterial pathogens in the root canals. DNA were extracted from the samples and amplified respectively using universal 16S rRNA primers and the 8 bacterial specific 16S rRNA primers. Results: 100%(23/23) of chronic apical periodontitis samples and 92.31%(24 /26)of endodontic flare-ups samples were positive for the presence of bacteria. In samples of endodontic flare-ups, the detecting rates of Prevotella nigrescens, Treponema denticola and Campylobacter rectus were significantly increased compared with samples of chronic apical peridodontitis (P<0.05) and there was a synergistic relationship between Bacteroides forsythus and Porphyromonas gingivalis in the root canal of endodontic interappointment emergency cases (P<0.05). Conclusions: Microbial infection, especially anaerobe, appeared to play an important role in the occurence of endodontic interappointment flare-ups.