title: Infection Control in Retreatment Cases: In Vivo Antibacterial Effects of 2 Instrumentation Systems.
abstract: BACKGROUND
  This in vivo study compared the antibacterial effects of 2 instrumentation systems in root canal-treated teeth with apical periodontitis.
  
  
  METHODS
  Forty-eight teeth with a single root and a single canal showing post-treatment apical periodontitis were selected for this study. For retreatment, teeth were randomly divided into 2 groups according to the instrumentation system used: Self-Adjusting File (SAF; ReDent-Nova, Ra'anana, Israel) and Twisted File Adaptive (TFA; SybronEndo, Orange, CA). In both groups, 2.5% sodium hypochlorite was the irrigant. Bacteriological samples were taken before (S1) and after chemomechanical preparation (S2). In the TFA group, passive ultrasonic irrigation (PUI) was performed after instrumentation, and samples were also taken after this supplementary step (S2b). DNA was extracted from the clinical samples and subjected to quantitative real-time polymerase chain reaction to evaluate the levels of total bacteria, streptococci, and Enterococcus faecalis. Statistical analyses from quantitative real-time polymerase chain reaction data were performed within groups using the Wilcoxon matched pairs test and between groups using the Mann-Whitney U test and the Fisher exact test with the significance level set at P < .05.
  
  
  RESULTS
  Bacteria were detected in S1 samples from 43 teeth, which were then included in the antibacterial experiment. Both SAF and TFA instrumentation protocols showed a highly significant intracanal bacterial reduction (P < .001). Intergroup quantitative comparisons disclosed no significant differences between TFA with or without PUI and SAF (P > .05). PUI did not result in significant improvement in disinfection (P > .05).
  
  
  CONCLUSIONS
  Both instrumentation systems/treatment protocols were highly effective in significantly reducing the intracanal bacterial counts. No significant difference was observed between the 2 systems in disinfecting the canals of teeth with post-treatment apical periodontitis.
authors.affiliation: Molecular Microbiology Laboratory, Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Rio de Janeiro, Brazil. Electronic address: recostaval@gmail.com.
authors.forename: Renata C V
authors.initials: RC
authors.lastname: Rodrigues
authors.affiliation: Molecular Microbiology Laboratory, Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Rio de Janeiro, Brazil; Department of Endodontics, Faculty of Dentistry, Grande Rio University, Duque de Caxias, Rio de Janeiro, Brazil.
authors.forename: Henrique S
authors.initials: HS
authors.lastname: Antunes
authors.affiliation: Molecular Microbiology Laboratory, Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Mônica A S
authors.initials: MA
authors.lastname: Neves
authors.affiliation: Molecular Microbiology Laboratory, Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: José F
authors.initials: JF
authors.lastname: Siqueira
authors.affiliation: Molecular Microbiology Laboratory, Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Isabela N
authors.initials: IN
authors.lastname: Rôças
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D058491:Bacterial Load; D002648:Child; D003786:Dental Pulp Cavity / Q000382:microbiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010485:Periapical Periodontitis / Q000382:microbiology / Q000517:prevention & control*; D019233:Retreatment; D012388:Root Canal Irrigants / Q000008:administration & dosage; D018915:Root Canal Preparation / Q000295:instrumentation*; D012973:Sodium Hypochlorite / Q000008:administration & dosage; D007507:Therapeutic Irrigation / Q000379:methods; D014465:Ultrasonics; D055815:Young Adult
chemical_list: D012388:Root Canal Irrigants; D012973:Sodium Hypochlorite
keywords: Chemomechanical preparation; Self-Adjusting File; Twisted File Adaptive; endodontic retreatment; passive ultrasonic irrigation; post-treatment apical periodontitis