title: An ex vivo quantification of the apically extruded bacteria following use of nickel-titanium rotary instruments.
abstract: OBJECTIVE
  The aim of this study was to evaluate the number of bacteria extruded apically from extracted teeth ex vivo after canal instrumentation using the five different engine-driven techniques utilizing nickel-titanium instruments.
  
  
  METHODS
  One-hundred and ten extracted maxillary central incisor teeth were used. Access cavities were prepared, and root canals were then contaminated with a suspension of Enterococcus faecalis and dried. The contaminated roots were divided into five experimental groups of 20 teeth each and one control group of 10 teeth: Group 1, HERO 642; Group 2, Flex Master; Group 3, Profile GT; Group 4, RoCe; Group 5, K3; and Group 6, control group. Bacteria extruded from the apical foramen during instrumentation were collected into vials. The microbiological samples from the vials were incubated in culture media for 24 hours. Colonies of bacteria were counted, and the results were given as the number of colony-forming units. The data obtained were analyzed using one-way ANOVA, with p = 0.05 as the level for statistical significance.
  
  
  RESULTS
  There was no significant difference as to the number of extruded bacteria between five engine-driven systems (p > 0.05).
  
  
  CONCLUSIONS
  All engine-driven nickel-titanium systems extruded bacteria through the apical foramen.
authors.affiliation: Department of Endodontics, Sadoughi University of Medical Sciences, Yazd, Iran. mohammadi_zahed@yahoo.com
authors.forename: Zahed
authors.initials: Z
authors.lastname: Mohammadi
mesh_terms: D015169:Colony Count, Microbial; D003722:Dental Alloys; D003762:Dental Instruments; D003786:Dental Pulp Cavity / Q000382:microbiology*; D013293:Enterococcus faecalis; D006801:Humans; D007180:Incisor; D009532:Nickel; D018915:Root Canal Preparation / Q000295:instrumentation*; D014025:Titanium; D019227:Tooth Apex
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium