title: Rotary Mtwo system versus manual K-file instruments: efficacy in preparing primary and permanent molar root canals.
abstract: OBJECTIVE
  To compare the cleaning ability and preparation time of rotary instruments (Mtwo) and conventional manual instruments (K-file) in preparing primary and permanent molar root canals.
  
  
  METHODS
  Access cavities were prepared in 70 primary and 70 permanent teeth and India ink was injected into 120 canals of selected molars. The teeth were randomly divided into two main subgroups (n=20) and three control groups (n=10). In each of these main subgroups, either the manual instrument (K-file) or the rotary system (Mtwo) was used to prepare root canals. After cleaning the canals and clearing the teeth, dye removal was evaluated with the help of a stereomicroscope. In addition, the time needed for root canal preparation was recorded by a chronometer.
  
  
  METHODS
  Statistical analyses were done using the Kruskal-Wallis, Mann-Whitney and t tests.
  
  
  RESULTS
  With regard to the cleaning ability of root canals, there were no significant differences between the K-file and Mtwo rotary system in primary and permanent teeth in the apical, middle or coronal third of the canals. Moreover, there were no significant differences between primary and permanent teeth prepared with K-files and rotary instruments. In all the groups, shorter times were recorded with the rotary technique. The working time was shorter in primary than in permanent teeth.
  
  
  CONCLUSIONS
  The Mtwo rotary system showed acceptable cleaning ability in both primary and permanent teeth, and achieved results similar to those of K-files in less time.
authors: Department of Endodontics, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran. azarm@sums.ac.ir
authors: Mohammad-Reza
authors: MR
authors: Azar
authors: Maziar
authors: M
authors: Mokhtare
mesh_terms: D002244:Carbon; D004396:Coloring Agents; D003722:Dental Alloys / Q000737:chemistry; D003786:Dental Pulp Cavity / Q000473:pathology*; D004867:Equipment Design; D004868:Equipment Failure; D006801:Humans; D008422:Materials Testing; D008963:Molar / Q000473:pathology*; D009532:Nickel / Q000737:chemistry; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D012399:Rotation; D013997:Time Factors; D014025:Titanium / Q000737:chemistry; D019227:Tooth Apex / Q000473:pathology; D014094:Tooth, Deciduous / Q000473:pathology*; D019415:Torque
chemical_list: D004396:Coloring Agents; D003722:Dental Alloys; C028433:chinese ink; C040654:titanium nickelide; D002244:Carbon; D009532:Nickel; D014025:Titanium