title: Apical transportation during removal of root canal filling with different retreatment systems.
abstract: BACKGROUND
  This study aimed to compare apical transportation during retreatment using ProTaper Universal retreatment (PTUR), Mtwo R and D-RaCe instruments in curved root canals.
  
  
  METHODS
  36 extracted mandibular molar teeth with curved mesiobuccal roots were selected. The teeth were embedded into acrylic blocks. The blocks were fixed on the experimental setup. After determining the working length (WL), mesiobuccal canals were prepared with ProTaper Universal rotary instruments to size F1 (20/0.06). After the obturation, the teeth were randomly divided into groups; the PTUR files were used as D1 (30/0.09) for coronal third and D2 (25/0.08) at WL. Mtwo R files, R1 (15/0.05) and R2 (25/0.05) were used at WL. D-RaCe files were used as DR1 (30/.10) in cervical third and DR2 (25/0.04) at WL. Image J analysis software was used to measure the apical transportation. Differences between the 3 groups were analyzed with a 1-way ANOVA or Kruskal-Wallis tests.
  
  
  RESULTS
  There was no significant difference between groups in the apical transportation in either the mesiodistal (p = 0.166) or buccolingual (p = 0.518) direction. Among the 3 groups, the apical transportation was the greatest in the D-RaCe group.
  
  
  CONCLUSIONS
  It can be concluded that all retreatment systems caused a similar level of apical transportation.
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Bülent Ecevit University, Zonguldak - Turkey.
authors.forename: Baran C
authors.initials: BC
authors.lastname: Sağlam
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Bülent Ecevit University, Zonguldak - Turkey.
authors.forename: Ersan
authors.initials: E
authors.lastname: Çiçek
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Bülent Ecevit University, Zonguldak - Turkey.
authors.forename: Mustafa M
authors.initials: MM
authors.lastname: Koçak
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Bülent Ecevit University, Zonguldak - Turkey.
authors.forename: Sibel
authors.initials: S
authors.lastname: Koçak
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Gazi University, Ankara - Turkey.
authors.forename: Bağdagül H
authors.initials: BH
authors.lastname: Kıvanç
mesh_terms: D003762:Dental Instruments; D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging*; D004867:Equipment Design; D006801:Humans; D008422:Materials Testing; D011897:Random Allocation; D019233:Retreatment; D018915:Root Canal Preparation / Q000295:instrumentation*; D019227:Tooth Apex / Q000000981:diagnostic imaging*