The occurrence of Enterococcus faecalis in teeth with failed endodontic treatments

The information about the microbiology of root canal treated teeth with persistent periapical lesion is very important, because the main cause of endodontic failure in such cases is persistent infection. The purpose of this study was to determine the occurrence of Enterococcus faecalis in teeth with failed endodontic treatment in an Iranian population. Methods & Materials: Twenty two asymptomatic root-filled teeth with chronic apical periodontitis were selected for retreatment. After removal of the root – filling material, the canal was sampled with paper points. All samples were grown under aerobic condition at 35 ˚c, then the bacterial growth was accurately analyzed. The finding indicated that bacteria were cultivated in 13 of the 22 (%59) teeth examined in the study. Enterococcus faecalis and staphylococcus aureus were the most commonly recovered bacteria. All cultivable bacteria were isolated in pure culture (monoinfection). It seems that some bacterial species (faculative anaerobes) with a special ecological resistance and high penetration ability have an important role in endodontic failures.