title: Microscopic evaluation of cleaning efficiency of three different nickel-titanium rotary instruments.
abstract: BACKGROUND
  This study compared the cleaning efficiency of Mtwo, Race and Medin Nickel-Titanium (NiTi) rotary instruments.
  
  
  METHODS
  Sixty mandibular molar mesial roots were selected with angle curvatures between 25-35 degrees and divided into three groups; each containing 20 teeth. Canals were prepared with the rotary files and irrigated with 2.5% NaOCl solution after each instrument. Total of 5mL of normal saline was used as the final rinse; subsequently the canals were dried with paper points. The amount of debris and smear layer in three parts of the root canal walls was evaluated using SEM and the data were analyzed by using the Kruskal-Wallis test and the Mann-Whitney U test.
  
  
  RESULTS
  The results for remnant debris in the coronal part of root canals were similar, whereas in the middle third, Mtwo instruments achieved significantly better results compared to Race and Medin instruments. In the apical third of the root canals more debris was created by Race instruments.
  
  
  CONCLUSIONS
  Overall, Mtwo instruments had greater success in producing clean canals.
authors.affiliation: Department of Endodontics, Dental Research Center of Mashad University of Medical Sciences, Mashhad, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Bidar
authors.forename: Saeed
authors.initials: S
authors.lastname: Moradi
authors.forename: Maryam
authors.initials: M
authors.lastname: Forghani
authors.forename: Salma
authors.initials: S
authors.lastname: Bidad
authors.forename: Mahtab
authors.initials: M
authors.lastname: Azghadi
authors.forename: Shahrzad
authors.initials: S
authors.lastname: Rezvani
authors.forename: Shirin
authors.initials: S
authors.lastname: Khoynezhad
keywords: NiTi Rotary; Root Canal Preparation; Scanning Electron Microscopy; Smear Layer