title: Reduction of Enterococcus faecalis in curved root canals after various sizes and tapers of canal preparation.
abstract: OBJECTIVE
  The aim of this study was to evaluate the reduction of Enterococcus faecalis in curved root canals after various sizes and tapers of the canal preparation.
  
  
  METHODS
  Mandibular first molars (n = 103) with curved mesiobuccal canals were divided into one control (n = 5) and 7 experimental (n = 14) groups, were inoculated with E. faecalis (ATTC 29212) and prepared with the following RaCe files (FKG Dentaire) as master apical file: Groups: 25.04, 25.06, 30.04, 30.06, 35.04, 35.06 and 40.06. All the experimental groups were irrigated with 2 mL of 1% sodium hypochlorite during instrumentation and finally rinsed with 17% ethylenediaminetetraacetic acid (EDTA) (2 mL) followed by 5.25% NaOCl (2 mL) and sterile distilled water. Colony counting was performed after incubation.
  
  
  METHODS
  Resulting data were analyzed using one-way ANOVA and Tukey's post-hoc test, (P < 0.05).
  
  
  CONCLUSIONS
  All the experimental groups showed significant bacterial reduction (P < 0.001). Although the greater the size/taper or both led to more decreased amount of bacteria, differences between the groups with the identical size and different tapers, and among the groups with the same taper and different sizes were not significant. Based on this study, 25.04 along with using 2 mL of 1% NaOCl during instrumentation, and using 17% EDTA and 5.25% NaOCl as final rinse successively after the termination of preparation, can effectively reduce intra-canal bacteria and preserve root structure.
authors.affiliation: Department of Endodontic, Dental Branch, Islamic Azad University, Tehran, Iran.
authors.forename: Amir Abbas
authors.initials: AA
authors.lastname: Moshari
authors.affiliation: Department of Endodontic, Dental Branch, Islamic Azad University, Tehran, Iran.
authors.forename: Nahid Mohammadzadeh
authors.initials: NM
authors.lastname: Akhlaghi
authors.affiliation: Food and Drug Control Laboratories, Food and Drug Laboratories Research Centre, Ministry of Health and Medical Education, Tehran, Iran.
authors.forename: Nahid
authors.initials: N
authors.lastname: Rahimifard
authors.affiliation: Dental Research Center Department, Dental Faculty, Birjand University of Medical Sciences, Birjand, Iran.
authors.forename: Soheila
authors.initials: S
authors.lastname: Darmiani
keywords: Debridement; Enterococcus faecalis; instrumentation; root canal irrigant; sodium hypochlorite