title: Computed Tomography Evaluation of Canal Transportation and Volumetric Changes in Root Canal Dentin of Curved Canals Using Mtwo, ProTaper and ProTaper Next Rotary System-An In-vitro Study.
abstract: BACKGROUND
  Complete cleaning and shaping of root canal system is of paramount importance to achieve a successful root canal treatment. There are various rotary Ni-Ti systems available in the market to achieve mechanical goal of root canal preparation. But aggressive preparation of root canal with such systems would result in canal transportation and excess root dentin removal that would be one of the major reasons to decide the prognosis of root canal treated tooth.
  
  
  OBJECTIVE
  The present study was conducted to compare the root canal preparation in terms of canal transportation and volumetric changes in the root canal dentin among three Ni-Ti file systems, namely Mtwo, ProTaper (PT) and ProTaper NEXT (PTN) file system, using Computed Tomography (CT).
  
  
  METHODS
  A total of 45 mesiobuccal root canals of extracted first molar teeth with completely formed root apices and angle of curvature ranging between 10°- 35° were selected. These teeth were randomly divided into three experimental groups containing 15 teeth each, based on rotary system used. Group-I: Mtwo files, Group-II: PT files and Group-III: PTN files. Pre-instrumentation CT images were obtained at three cross-sectional planes - 3mm, 7mm and 11mm from apical end of the root. Similarly, post-instrumentation images were obtained. Shortest distance from the edge of the canal to the periphery of the root was analyzed by using Analysis of Variance.
  
  
  RESULTS
  All three file systems tested in the present study presented similar behaviour with respect to the root canal transportation. Lesser canal transportation was recorded in Mtwo. But no statistically significant difference was seen in terms of canal transportation and volume of dentin removed between all three rotary systems (p>0.05).
  
  
  CONCLUSIONS
  Mtwo, PT and PTN rotary systems have similar behaviour with respect to canal transportation and volume of dentin removed.
authors.affiliation: Senior Dental Health Officer, Government Hospital , Tumukur, Karnataka, India .
authors.forename: Mayuri Biccodu
authors.initials: MB
authors.lastname: Shivashankar
authors.affiliation: Reader, Department of Conservative Dentistry and Endodontics, Bapuji Dental College and Hospital , Davangere, Karnataka, India .
authors.forename: Nandini Thippannanavar
authors.initials: NT
authors.lastname: Niranjan
authors.affiliation: Senior Lecturer, Department of Conservative Dentistry and Endodontics, Bapuji Dental College and Hospital , Davangere, Karnataka, India .
authors.forename: Arun
authors.initials: A
authors.lastname: Jayasheel
authors.affiliation: Professor, Department of Conservative Dentistry and Endodontics, Bapuji Dental College and Hospital , Davangere, Karnataka, India .
authors.forename: Mallikarjun Goud
authors.initials: MG
authors.lastname: Kenchanagoudra
keywords: 3D imaging; Ni-Ti file system; Root canal treatment