title: Removal of Root Canal Fillings in Curved Canals Using Either Reciprocating Single- or Rotary Multi-instrument Systems and a Supplementary Step with the XP-Endo Finisher.
abstract: BACKGROUND
  This study compared the efficacy of a reciprocating single-instrument system and a rotary multi-instrument system followed by a supplementary approach with a finishing instrument in removing the filling material from curved canals during retreatment.
  
  
  METHODS
  Forty mesial canals from extracted mandibular molars were instrumented and filled. Then, each mesial canal was retreated by using either Reciproc (VDW, Munich, Germany) or Mtwo (VDW) instruments, alternating the technique used per canal from root to root. The working time was recorded, and the percentage of removed filling volume was assessed by means of micro-computed tomography imaging before and after retreatment. Canals still showing filling material remnants were subjected to an adjunctive approach with the XP-Endo Finisher (FKG Dentaire, La Chaux-de-Fonds, Switzerland), and another microCT scan was taken. Data were statistically analyzed with a significance level of 5%.
  
  
  RESULTS
  The percentage of filling material removed with Mtwo instruments (96%) was significantly higher than Reciproc (89%) (P < .05), both used up to a final instrument size of 40. Mtwo required less time to remove the filling material than Reciproc (P < .05). Intragroup analysis in the Reciproc group showed that the R40 instrument removed significantly more filling material than R25 (P < .05). The supplementary approach with the XP-Endo Finisher was effective in significantly enhancing the removal of filling material (P < .05).
  
  
  CONCLUSIONS
  The rotary multiple-instrument system was more effective and faster than the reciprocating single-instrument approach in removing previous root canal fillings. As for the Reciproc group, it was observed that the larger instrument promoted significantly better results. The adjunctive finishing instrument XP-Endo Finisher significantly improved filling material removal.
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Rio de Janeiro, Brazil. Electronic address: flavioferreiraalves@gmail.com.
authors.forename: Flávio R F
authors.initials: FR
authors.lastname: Alves
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Marília F
authors.initials: MF
authors.lastname: Marceliano-Alves
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Rio de Janeiro, Brazil; Department of Endodontics, Faculty of Dentistry, University Center of João Pessoa, Paraíba, Brazil.
authors.forename: Júlio Cézar N
authors.initials: JC
authors.lastname: Sousa
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Stephanie B
authors.initials: SB
authors.lastname: Silveira
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: José C
authors.initials: JC
authors.lastname: Provenzano
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: José F
authors.initials: JF
authors.lastname: Siqueira
mesh_terms: D003762:Dental Instruments; D004867:Equipment Design; D006801:Humans; D066298:In Vitro Techniques; D008963:Molar; D012387:Root Canal Filling Materials; D012389:Root Canal Obturation / Q000295:instrumentation*; D055114:X-Ray Microtomography
chemical_list: D012387:Root Canal Filling Materials
keywords: Endodontic retreatment; reciprocating single-file system; root canal preparation; rotary instruments