title: Correlative bacteriologic and micro-computed tomographic analysis of mandibular molar mesial canals prepared by self-adjusting file, reciproc, and twisted file systems.
abstract: BACKGROUND
  This ex vivo study evaluated the disinfecting and shaping ability of 3 protocols used in the preparation of mesial root canals of mandibular molars by means of correlative bacteriologic and micro-computed tomographic (μμCT) analysis.
  
  
  METHODS
  The mesial canals of extracted mandibular molars were contaminated with Enterococcus faecalis for 30 days and assigned to 3 groups based on their anatomic configuration as determined by μCT analysis according to the preparation technique (Self-Adjusting File [ReDent-Nova, Ra'anana, Israel], Reciproc [VDW, Munich, Germany], and Twisted File [SybronEndo, Orange, CA]). In all groups, 2.5% NaOCl was the irrigant. Canal samples were taken before (S1) and after instrumentation (S2), and bacterial quantification was performed using culture. Next, mesial roots were subjected to additional μCT analysis in order to evaluate shaping of the canals.
  
  
  RESULTS
  All instrumentation protocols promoted a highly significant intracanal bacterial reduction (P < .001). Intergroup quantitative and qualitative comparisons disclosed no significant differences between groups (P > .05). As for shaping, no statistical difference was observed between the techniques regarding the mean percentage of volume increase, the surface area increase, the unprepared surface area, and the relative unprepared surface area (P > .05). Correlative analysis showed no statistically significant relationship between bacterial reduction and the mean percentage increase of the analyzed parameters (P > .05).
  
  
  CONCLUSIONS
  The 3 instrumentation systems have similar disinfecting and shaping performance in the preparation of mesial canals of mandibular molars.
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Rio de Janeiro, Brazil. jf_siqueira@yahoo.com
authors.forename: José F
authors.initials: JF
authors.lastname: Siqueira
authors.forename: Flávio R F
authors.initials: FR
authors.lastname: Alves
authors.forename: Marco A
authors.initials: MA
authors.lastname: Versiani
authors.forename: Isabela N
authors.initials: IN
authors.lastname: Rôças
authors.forename: Bernardo M
authors.initials: BM
authors.lastname: Almeida
authors.forename: Mônica A S
authors.initials: MA
authors.lastname: Neves
authors.forename: Manoel D
authors.initials: MD
authors.lastname: Sousa-Neto
mesh_terms: D058491:Bacterial Load; D018441:Biofilms; D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging / Q000382:microbiology*; D013293:Enterococcus faecalis / Q000302:isolation & purification*; D004867:Equipment Design; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D008334:Mandible; D008855:Microscopy, Electron, Scanning; D008963:Molar / Q000000981:diagnostic imaging / Q000382:microbiology*; D012388:Root Canal Irrigants / Q000627:therapeutic use; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D055114:X-Ray Microtomography / Q000379:methods*
chemical_list: D012388:Root Canal Irrigants; D012973:Sodium Hypochlorite
keywords: Bacterial reduction; Self-Adjusting File; endodontic treatment; micro–computed tomography; reciprocating motion; single-file instrumentation