title: A micro-computed tomography assessment of the efficacy of rotary and reciprocating techniques for filling material removal in root canal retreatment.
abstract: OBJECTIVE
  The aim of this study was to compare the efficacy of rotary and reciprocating techniques for removing filling material from root canals, using micro-computed tomography (micro-CT) imaging.
  
  
  METHODS
  The distal root canals of 42 human mandibular molars were instrumented with hand files up to size 40 according to a step-down technique and obturated with gutta-percha and an epoxy resin-based sealer using Tagger's hybrid technique. Teeth were divided into six groups (n = 7) according to the instruments used for removal of filling material: group PTUR (Protaper Universal Retreatment), group W40 (WaveOne 40.08), group R40 (Reciproc 40.06), group R50 (Reciproc 50.05), group W25/W40 (WaveOne 25.08/40.08), and group R25/R40/R50 (Reciproc 25.08/40.06/50.05). Teeth were scanned with a micro-CT device before and after use of the instruments to calculate the percentage of remaining filling material. Data were compared using one-way ANOVA and Fisher's LSD test at 5 % significance level.
  
  
  RESULTS
  The mean percentage of remaining filling material was significantly lower when canals were retreated with the set of instruments R25/R40/R50 and single instruments W40 and R50 compared with the set of instruments W25/W40 (P < 0.05), which promoted material compaction in the apical region.
  
  
  CONCLUSIONS
  None of the retreatment techniques removed the root fillings completely. PTUR instruments performed equally effective regarding filling removal compared with W40, R40, R50, W25/W40, and R25/R40/R50. For WaveOne, the use of a single instrument (size 40, taper 0.08) was more effective in removing filling material, while for Reciproc showed similar cleaning ability using single instrument or combination of instruments.
  
  
  CONCLUSIONS
  The results of this in vitro study provide consistent information on filling material removal capacity of mechanized systems during retreatment at the different root canal thirds.
authors.affiliation: Department of Restorative Dentistry, Dental School of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
authors.forename: Bruno
authors.initials: B
authors.lastname: Monguilhott Crozeta
authors.affiliation: Department of Restorative Dentistry, Dental School of Ribeirão Preto, University of São Paulo, São Paulo, Brazil. sousanet@forp.usp.br.
authors.forename: Manoel
authors.initials: M
authors.lastname: Damião de Sousa-Neto
authors.affiliation: Department of Restorative Dentistry, Dental School of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
authors.forename: Graziela
authors.initials: G
authors.lastname: Bianchi Leoni
authors.affiliation: Department of Restorative Dentistry, Dental School of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
authors.forename: Jardel
authors.initials: J
authors.lastname: Francisco Mazzi-Chaves
authors.affiliation: Department of Endodontics, School of Dentistry, University of Ribeirão Preto, Ribeirão Preto, SP, Brazil.
authors.forename: Yara
authors.initials: Y
authors.lastname: Terezinha Corrêa Silva-Sousa
authors.affiliation: Department of Dentistry, Positivo University, Curitiba, PR, Brazil.
authors.forename: Flares
authors.initials: F
authors.lastname: Baratto-Filho
mesh_terms: D003762:Dental Instruments; D006801:Humans; D066298:In Vitro Techniques; D008334:Mandible; D008963:Molar / Q000000981:diagnostic imaging* / Q000601:surgery*; D012387:Root Canal Filling Materials; D012389:Root Canal Obturation / Q000295:instrumentation / Q000379:methods*; D055114:X-Ray Microtomography / Q000379:methods*
chemical_list: D012387:Root Canal Filling Materials
keywords: Micro-computed tomography; Reciproc; Reciprocating motion; Root canal retreatment; WaveOne
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