title: Bacteria isolated after unsuccessful endodontic treatment in a North American population.
abstract: OBJECTIVE
  The purpose of this study was to determine the composition of the microbial flora present in teeth after the failure of root canal therapy in a North American population. These results were then compared with those of the previous Scandinavian studies.
  
  
  METHODS
  Fifty-four root-filled teeth with persistent periapical radiolucencies were selected for retreatment. After removal of the root-filling material, the canals were sampled with paper points, and by reaming of the apical dentin. Both samples were grown under aerobic and strict anaerobic conditions. Then the bacterial growth was analyzed.
  
  
  RESULTS
  The microbial flora was mainly of 1 to 2 strains of predominantly gram-positive organisms. Enterococcus faecalis was the most commonly recovered bacterial species.
  
  
  CONCLUSIONS
  Bacteria were cultivated in 34 of the 54 teeth examined in the study. E faecalis was identified in 30% of the teeth with a positive culture.
authors.affiliation: Department of Endodontics, University of North Carolina School of Dentistry, NC, USA.
authors.forename: H H
authors.initials: HH
authors.lastname: Hancock
authors.forename: A
authors.initials: A
authors.lastname: Sigurdsson
authors.forename: M
authors.initials: M
authors.lastname: Trope
authors.forename: J
authors.initials: J
authors.lastname: Moiseiwitsch
mesh_terms: D000190:Actinomyces / Q000254:growth & development; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001419:Bacteria / Q000145:classification* / Q000254:growth & development; D016010:Binomial Distribution; D003786:Dental Pulp Cavity / Q000382:microbiology*; D003804:Dentin / Q000382:microbiology; D013293:Enterococcus faecalis / Q000254:growth & development; D005260:Female; D006094:Gram-Positive Bacteria / Q000145:classification / Q000254:growth & development; D006801:Humans; D008297:Male; D008875:Middle Aged; D009657:North Carolina; D010462:Peptostreptococcus / Q000254:growth & development; D010485:Periapical Periodontitis / Q000382:microbiology / Q000628:therapy; D019233:Retreatment; D012390:Root Canal Therapy; D012537:Scandinavian and Nordic Countries; D018709:Statistics, Nonparametric; D013291:Streptococcus / Q000254:growth & development; D017211:Treatment Failure