Purpose: to investigate the microbial flora of teeth with failed root-canal treatment and the association of constituent species with clinical features
N= 60 teeth. Included: teeth that were previously filled (> 2 yrs) and present with PA lesion Excluded: Patients who had received antibiotic treatment during the last 3 months or had a general disease.
•The following features were recorded for each patient: tooth type, clinical symptoms, presence or absence of a sound coronal restoration, caries, sinus, swelling of periodontal tissues, tenderness to percussion, mobility, periodontal status of the tooth, status of the root canal in terms of whether dry or wet and the radiographic quality of the obturation.
•Rubber dam was applied and the teeth were accessed and disinfected. •Access prepared, Gutta-percha removed mechanichally without use of chemical solvent. irrigation done by saline.
•bacterial samples were obtained using paper points and transformed to a transport medium.
•isolation and species determination were performed using advanced microbiological techniques for anaerobic species.
•The association of microbiological findings with clinical features was investigated.
Most highlighted Results:
•Microorganisms were recovered from 51 teeth (85%) .
•In most cases (60%), one or two strains per canal were found.
•Of the microbial species isolated, 57.4% were facultative anaerobic species and 83.3% Gram-positive microorganisms
•Enterococcus faecalis was the most frequently recovered bacterial species (52% of cases with bacterial growth).
•Significant associations were also observed between:
(a) pain or history of pain and polymicrobial infections or anaerobes;
(b) tenderness to percussion and Prevotella intermedia/P. nigrescens
(c) sinus and Streptococcus spp. or Actinomyces spp.
(d) coronally unsealed teeth and Streptococcus spp. or Candida spp.
These findings should direct further studies at methods to eliminate infection during re-treatment, in order to improve the prognosis.