Abstract
Background and aims. The aim of this study was to determine the microorganisms prevalent in the necrotic dental pulp and root
canals of unsuccessfully treated teeth.
Materials and methods. The present study was conducted on 150 single-rooted teeth of patients referring to a dental clinic.
Sampling was performed by placing a sterile paper point in the canal for 60 s. Bacterial samples were evaluated by a microbiological
technique specific for anaerobic species, used for isolation and identification of sampled strains.
Results. From the 150 samples taken, 101 were from necrotic pulps (primary infection) and 49 were from the teeth with an
unsuccessful endodontic treatment (secondary infection).
Conclusion. Enterococcus faecalis was a prevalent species in the failed root canals evaluated.