title: Effect of finishing instrumentation using NiTi hand files on volume, surface area and uninstrumented surfaces in C-shaped root canal systems.
abstract: OBJECTIVE
  To assess the effect of 90°-oscillatory instrumentation with hand files on several morphological parameters (volume, surface area and uninstrumented surface) in C-shaped root canals after instrumentation using a single-file reciprocation system (Reciproc; VDW, Munich, Germany) and a Self-Adjusting File System (SAF; ReDent Nova, Ra'anana, Israel).
  
  
  METHODS
  Twenty mandibular second molars with C-shaped canals and C1 canal configurations were divided into two groups (n = 10) and instrumented with Reciproc and SAF instruments. A size 30 NiTi hand K-file attached to a 90°-oscillatory motion handpiece was used as final instrumentation in both groups. The specimens were scanned using micro-computed tomography after all procedures. Volume, surface area increase and uninstrumented root canal surface were analysed using CTAn software (Bruker-microCT, Kontich, Belgium). Also, the uninstrumented root canal surface was calculated for each canal third. All values were compared between groups using the Mann-Whitney test and within groups using the Wilcoxon's signed-rank test.
  
  
  RESULTS
  Instrumentation with Reciproc significantly increased canal volume compared with instrumentation with SAF. Additionally, the canal volumes were significantly increased after 90°-oscillatory instrumentation (between and within group comparison; (P < 0.05)). Regarding the increase in surface area after all instrumentation protocols, statistical analysis only revealed significant differences in the within groups comparison (P < 0.05). Reciproc and SAF instrumentation yielded an uninstrumented root canal surface of 28% and 34%, respectively, which was not significantly different (P > 0.05). Final oscillatory instrumentation significantly reduced the uninstrumented root canal surface from 28% to 9% (Reciproc) and from 34% to 15% (SAF; P < 0.05). The apical and middle thirds exhibited larger uninstrumented root canal surfaces after the first instrumentation that was significantly reduced after oscillatory instrumentation (P < 0.05).
  
  
  CONCLUSIONS
  The Reciproc and SAF system were associated with similar morphological parameters after instrumentation of mandibular second molars with C-shaped canals except for a higher canal volume increase in the Reciproc group compared to the SAF. Furthermore, the final use of 90°-oscillatory instrumentation using NiTi hand files significantly decreased the uninstrumented canal walls that remained after Reciproc and SAF instrumentation.
authors.affiliation: Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil.
authors.forename: P
authors.initials: P
authors.lastname: Amoroso-Silva
authors.affiliation: Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil.
authors.forename: M P
authors.initials: MP
authors.lastname: Alcalde
authors.affiliation: Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil.
authors.forename: M A
authors.initials: MA
authors.lastname: Hungaro Duarte
authors.affiliation: Department of Endodontics, Grande Rio University, Rio de Janeiro, Brazil.
authors.forename: G
authors.initials: G
authors.lastname: De-Deus
authors.affiliation: Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil.
authors.forename: R
authors.identifier: http://orcid.org/0000-0001-9738-0828
authors.initials: R
authors.lastname: Ordinola-Zapata
authors.affiliation: Division of Endodontics, Department of Restorative Dentistry, University of São Paulo, São Paulo, Brazil.
authors.forename: L G
authors.initials: LG
authors.lastname: Freire
authors.affiliation: Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil.
authors.forename: B C
authors.initials: BC
authors.lastname: Cavenago
authors.affiliation: Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil.
authors.forename: I G
authors.initials: IG
authors.lastname: De Moraes
mesh_terms: D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging / Q000601:surgery; D006801:Humans; D008963:Molar / Q000000981:diagnostic imaging / Q000601:surgery; D009532:Nickel; D012390:Root Canal Therapy / Q000295:instrumentation* / Q000379:methods; D014025:Titanium; D055114:X-Ray Microtomography
chemical_list: C040654:titanium nickelide; D009532:Nickel; D014025:Titanium
keywords: C-shaped root canal; Reciproc; Self-Adjusting File; micro-CT; nickel-titanium; root canal preparation