title: Comparison of centring ability and transportation between four nickel titanium instrumentation techniques by micro-computed tomography.
abstract: OBJECTIVE
  To compare the centring ability and transportation of ProTaper Next (PTN), ProTaper Universal (PTU), Race 123 and RevoS using micro-computed tomography (μCT).
  
  
  METHODS
  Sixty mesial root canals of thirty mandibular molars were divided virtually into coronal, middle and apical thirds, and two reproducible reference points were marked on the external surface of the roots creating 360 measurement points. Samples were randomly allocated to four NiTi instrumentation techniques. Group 1: PTU up to F2 (n = 16), group 2: PTN up to X2 (n = 18), group 3: Race 123 up to T2 (n = 12) and group 4: RevoS up to SU (n = 14). To reproduce a clinical situation, samples were prepared on a phantom head using a surgical operating microscope. Samples were scanned pre- and postoperatively using μCT to compare and calculate the transportation and centring ratio. The data were analysed using parametric statistics.
  
  
  RESULTS
  In the coronal and middle third of the root canals, there were significant differences in centring between PTN and PTU (coronal P < 0.001), PTN and RevoS (coronal P < 0.001), Race and PTU (coronal P < 0.01), Race and RevoS (coronal P < 0.01), PTN and RevoS (middle P < 0.01) and Race and RevoS (P < 0.05). Furthermore, there were significant differences in centring between PTN root canal preparations and other instruments in the apical third (PTN and PTU P < 0.01, PTN and Race P < 0.001, PTN and RevoS P < 0.001). In terms of transportation, in the coronal third, there was a significant difference between PTN and PTU (P < 0.05). However, there were no significant differences between the other instruments. In the middle third, significant differences were observed between PTN and PTU (P < 0.05), PTN and RevoS (P < 0.05), Race and PTU (P < 0.05) and Race and RevoS (P < 0.05). However, there were no significant differences between other systems. There was no significant difference in terms of transportation between the four systems in the apical third.
  
  
  CONCLUSIONS
  ProTaper Next prepared more centred root canal shapes when compared with Race, PTU and RevoS. In the coronal and middle third of the root canals, the differences in centring between PTN and PTU/RevoS were significant. PTN root canal preparations were more centred than those achieved with all other instruments in the apical third.
authors.affiliation: Department of Conservative Dentistry and Endodontology, King's College London Dental Institute, London, UK.
authors.forename: N
authors.initials: N
authors.lastname: Saberi
authors.affiliation: Department of Conservative Dentistry and Endodontology, King's College London Dental Institute, London, UK.
authors.forename: S
authors.initials: S
authors.lastname: Patel
authors.affiliation: Department of Conservative Dentistry and Endodontology, King's College London Dental Institute, London, UK.
authors.forename: F
authors.initials: F
authors.lastname: Mannocci
mesh_terms: D003762:Dental Instruments; D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging / Q000601:surgery; D006801:Humans; D008963:Molar / Q000000981:diagnostic imaging / Q000601:surgery; D009532:Nickel; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D014025:Titanium; D055114:X-Ray Microtomography
chemical_list: C040654:titanium nickelide; D009532:Nickel; D014025:Titanium
keywords: NiTi; ProTaper Next; RevoS; canal transportation; centring ratio; micro-CT