title: Effect of three nickel-titanium rotary file techniques on infected root dentin reduction.
abstract: OBJECTIVE
  This study compared the bacterial reduction of in vitro infected root canals after instrumentation by 3 nickel-titanium (NiTi) rotary files with different taper and diameter versus manual stainless steel files.
  
  
  METHODS
  Sixty-four single-rooted human teeth were infected with a suspension of Streptococcus sanguis measured by optical density. Teeth were divided randomly into 4 groups of 16 and prepared with Flexofiles, GT rotary files, HERO 642, and ProFile. Bacterial samplings were performed before (S1), during (S2-S3), and after (S4) instrumentation.
  
  
  RESULTS
  All techniques significantly reduced the number of bacterial cells in the root canals (P < .05). There was no significant difference between NiTi and manual instrumentation at S2, S3, or S4. Concerning bacterial reduction, the results suggest that a manual stainless steel file preparation is as efficient as a NiTi rotary instrumentation.
  
  
  CONCLUSIONS
  Regardless of the root canal preparation technique, its taper, and diameter, the root dentin remained infected and was not bacteria-free at the end of the experiment.
authors.affiliation: Department of Endodontics, Faculty of Odontology, Université Victor Segalen, Bordeaux, France.
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Chuste-Guillot
authors.forename: Cécile
authors.initials: C
authors.lastname: Badet
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Peli
authors.forename: Fabienne
authors.initials: F
authors.lastname: Perez
mesh_terms: D000704:Analysis of Variance; D003722:Dental Alloys; D003762:Dental Instruments; D003786:Dental Pulp Cavity / Q000382:microbiology*; D003804:Dentin / Q000382:microbiology*; D004867:Equipment Design; D006801:Humans; D009532:Nickel; D012388:Root Canal Irrigants; D018915:Root Canal Preparation / Q000295:instrumentation*; D012973:Sodium Hypochlorite; D013193:Stainless Steel; D013290:Streptococcal Infections; D013298:Streptococcus sanguis; D014025:Titanium
chemical_list: D003722:Dental Alloys; D012388:Root Canal Irrigants; C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium; D012973:Sodium Hypochlorite