title: Root canal retreatment using reciprocating and continuous rotary nickel-titanium instruments.
abstract: OBJECTIVE
  The complete filling material removal during endodontic retreatment is a clinical procedure difficult to achieve. The aim of this study was to evaluate the efficacy of reciprocating and continuous rotary nickel-titanium instruments used in root canal retreatment.
  
  
  METHODS
  Forty freshly extracted human premolars were cleaned and shaped by the crown-down technique, followed by filling by the lateral compaction technique. The teeth were randomly separated into two groups (n = 20), according to the system used for filling material removal: G1 - Reciproc and G2 - ProTaper Universal Retreatment System. The teeth were photographed under operating microscope at ×8 magnification; and the total area of the root canal and remaining filling material were quantified.
  
  
  RESULTS
  No statistically significant difference (P > 0.05) in residual filling material was observed between groups; however, the time required for filling removal was significantly shorter for Reciproc system (P < 0.05).
  
  
  CONCLUSIONS
  It was observed remaining filling material in all teeth, irrespective of the system used; however, root canal retreatment was faster when reciprocating motion was used.
authors.affiliation: Department of Endodontics, State University of Amazonas, Manaus, Amazonas, Brazil.
authors.forename: Patricia Fonseca
authors.initials: PF
authors.lastname: de Souza
authors.affiliation: Department of Endodontics, State University of Amazonas, Manaus, Amazonas, Brazil.
authors.forename: Leonardo Cantanhede Oliveira
authors.initials: LCO
authors.lastname: Goncalves
authors.affiliation: Department of Endodontics, State University of Amazonas, Manaus, Amazonas, Brazil.
authors.forename: Andre Augusto Franco
authors.initials: AAF
authors.lastname: Marques
authors.affiliation: Department of Endodontics, Federal University of Amazonas, Manaus, Amazonas, Brazil.
authors.forename: Emilio Carlos Sponchiado
authors.initials: ECS
authors.lastname: Junior
authors.affiliation: Department of Physiology and Pathology, Araraquara School of Dentistry, Univ Estadual Paulista, Araraquara, São Paulo, Brazil.
authors.forename: Lucas da Fonseca Roberti
authors.initials: LDFR
authors.lastname: Garcia
authors.affiliation: Department of Endodontics, State University of Amazonas, Manaus, Amazonas, Brazil.
authors.forename: Fredson Marcio Acris
authors.initials: FMA
authors.lastname: de Carvalho
keywords: Reciprocating motion; root canal retreatment; rotary instruments