title: The Impact of Three Different Canal Lubricants on Fracture, Deformity and Metal Slivering of ProTaper Rotary Instruments.
abstract: BACKGROUND
  The aim of this in vitro study was to evaluate the effect(s) of three canal lubricants i.e. sodium hypochlorite, RC-Prep as the paste form of ethylenediaminetetraacetic acid (EDTA) and aqueous EDTA on the occurrence/incidence of fracture, deformity and metal slivering of ProTaper rotary instruments.
  
  
  METHODS
  A total of 120 mesial canals (i.e. mesiobuccal and mesiolingual) of first mandibular molars or buccal canals (i.e. mesiobuccal and distobuccal) of first maxillary molars, with curvatures of 10-20 degrees were selected and randomly divided into three groups of forty samples each. These selected canals all had approximate 19-21 mm working length and apical diameter equal to a #15 K-file. In each group, the root canals were prepared using ProTaper rotary instruments with an electric motor using one of the three aforementioned irrigants. Subsequently, samples were compared to each other at different magnifications (16×, 20×, 40× and 57×) for any fracture, deformity or metal slivering, by the Cox regression analysis.
  
  
  RESULTS
  The fractures rate of samples in RC-Prep group was significantly higher compared to other groups (P=0.01). No evidence of instrument deformity was detected in any groups. A statistically significant reverse relation between metal slivering and instrument fracture was observed.
  
  
  CONCLUSIONS
  Application of aqueous EDTA and/or sodium hypochlorite as intracanal lubricants caused less fracture of ProTaper instruments compared to canal lubrication with RC-Prep.
authors.affiliation: Department of Endodontics, Dental School, Shahid Beheshti University of Medical Sciences, Tehran, Iran; ; Iranian Center for Endodontic Research, Research Institute of Dental sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Yazdan
authors.initials: Y
authors.lastname: Shantiaee
authors.affiliation: Department of Endodontics, Dental School, Shahid Beheshti University of Medical Sciences, Tehran, Iran; ; Iranian Center for Endodontic Research, Research Institute of Dental sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Omid
authors.initials: O
authors.lastname: Dianat
authors.affiliation: Endodontic Department, Dental School, Tehran University of Medical Sciences;
authors.forename: Farnoud
authors.initials: F
authors.lastname: Sharifi
authors.affiliation: Dental Student, Shahid Beheshti University of Medical Sciences, Tehran, Iran;
authors.forename: Golnaz
authors.initials: G
authors.lastname: Nahvi
authors.affiliation: Department of Biology (Biochemistry), School of Science, Payam e Noor university, Tehran, Iran.
authors.forename: Golbarg
authors.initials: G
authors.lastname: Kolahi Ahari
keywords: Canal Lubricants; EDTA; File Deformity; File Fracture; RC-Prep