title: Evaluation of apically extruded debris during root canal retreatment with several NiTi systems.
abstract: OBJECTIVE
  To compare the amount of debris extruded apically during root canal retreatment using ProTaper, Mtwo and Reciproc instruments with hand H-files.
  
  
  METHODS
  In total, 60 freshly extracted human mandibular incisor teeth were used. All root canals were prepared with a Reciproc R25 file than filled with Gutta-percha and AH Plus sealer using cold lateral condensation before being assigned randomly to four groups (n = 15 each). In group 1, root fillings were removed with the Protaper Universal retreatment system; ProTaper Universal F3 and F4 instruments were used for the final preparation. In group 2, root fillings were removed with the Mtwo retreatment system; Mtwo size 30, .06 taper, size 35, .06 taper and size 40, .06 taper files were used for the final preparation. In group 3, root fillings were removed with Reciproc R25 instruments; Reciproc R40 instruments were used for the final preparation. In group 4, the root fillings were removed with Gates Glidden burs and sizes 35, 30 and 25 H-files; for final preparation, a size 40 H-file was used. Glass vials were used for debris collection. The vials were weighed before and after Gutta-percha removal. Additionally, the times required for the retreatment procedures were recorded. Data were analysed statistically using one-way analysis of variance.
  
  
  RESULTS
  The Reciproc system produced significantly smaller amounts of apical extruded debris than the other groups (P < 0.05). There was no significant difference between the Mtwo, H-file and ProTaper groups. The ProTaper and Reciproc groups required significantly less time than the Mtwo and H-file groups (P < 0.001).
  
  
  CONCLUSIONS
  Use of the reciprocating single file system resulted in the extrusion of significantly less debris compared with the full-sequence rotary NiTi instruments and hand filing. Use of the ProTaper and Reciproc instruments required less time for retreatment procedures than use of the Mtwo or H-file.
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Bezmialem Vakıf University, İstanbul, Turkey.
authors.forename: A N
authors.initials: AN
authors.lastname: Dincer
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Trakya University, Edirne, Turkey.
authors.forename: O
authors.initials: O
authors.lastname: Er
authors.affiliation: Private Practice Limited to Endodontics, Kayseri, Turkey.
authors.forename: B C
authors.initials: BC
authors.lastname: Canakci
mesh_terms: D003762:Dental Instruments; D004853:Epoxy Resins; D004867:Equipment Design; D006171:Gutta-Percha; D006801:Humans; D066298:In Vitro Techniques; D007180:Incisor; D008422:Materials Testing; D009532:Nickel; D019233:Retreatment; D012387:Root Canal Filling Materials; D012389:Root Canal Obturation / Q000379:methods; D018915:Root Canal Preparation / Q000295:instrumentation*; D013499:Surface Properties; D014025:Titanium
chemical_list: D004853:Epoxy Resins; D012387:Root Canal Filling Materials; C534916:epoxy resin-based root canal sealer; C040654:titanium nickelide; D009532:Nickel; D006171:Gutta-Percha; D014025:Titanium
keywords: Mtwo; ProTaper; Reciproc; apical extrusion; retreatment