Shaping ability of single-file reciprocating and heat-treated multifile rotary systems: a micro-CT study.
OBJECTIVE
To investigate changes in three-dimensional geometry, in various cross-sectional morphological parameters and in the centring ability of root canals prepared with different preparation systems using microcomputed tomographic imaging technology.


METHODS
Sixty-four mesial canals of mandibular molars were matched based on similar morphological dimensions using micro-CT evaluation and assigned to four experimental groups (n = 16), according to the canal preparation technique: Reciproc, WaveOne, Twisted File and HyFlex CM systems. Changes in several 2D (area, perimeter, form factor, roundness, minor and major diameter) and 3D [volume, surface area, structure model index (SMI)] morphological parameters, as well as canal transportation, were compared with preoperative values using Kruskal-Wallis and anovapost hoc Tukey's tests with the significance level set at 5%.


RESULTS
Preparation significantly increased all tested parameters in the experimental groups. No significant differences were observed between groups regarding changes in volume, surface area, SMI, form factor and roundness of the root canal after preparation (P > 0.05). In the apical third, the Reciproc group had significantly greater changes in canal area, perimeter, major and minor diameters than the other groups (P < 0.05). Overall, the Twisted File and HyFlex CM systems were associated with significantly less transportation than the reciprocating instruments, Reciproc and WaveOne (P < 0.05).


CONCLUSIONS
Shaping procedures led to the enlargement of the root canal space with no evidence of significant preparation errors. Changes in 3D parameters were not different between groups whilst, in the apical third, Reciproc was associated with significantly greater changes in several 2D parameters compared to the other groups. Twisted File and HyFlex CM systems were able to maintain the original canal anatomy with less canal transportation than Reciproc and WaveOne; however, these differences are unlikely to be of clinical significance.
Proclin Department, School of Dentistry, Rio de Janeiro State University, Rio de Janeiro, Brazil.
M F V
MF
Marceliano-Alves
Department of Restorative Dentistry, Dental School of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
M D
MD
Sousa-Neto
Proclin Department, School of Dentistry, Rio de Janeiro State University, Rio de Janeiro, Brazil.
S R
SR
Fidel
Warwick Dentistry, The University of Warwick, Coventry, UK.
L
L
Steier
Physical Sciences of Imaging in the Biomedical Sciences, University of Birmingham, Birmingham, UK.
J P
JP
Robinson
Department of Restorative Dentistry, Dental School of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
J D
JD
Pécora
Department of Restorative Dentistry, Dental School of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
M A
MA
Versiani
D003762:Dental Instruments; D004867:Equipment Design; D006801:Humans; D066298:In Vitro Techniques; D008963:Molar / Q000000981:diagnostic imaging* / Q000601:surgery*; D018915:Root Canal Preparation / Q000295:instrumentation*; D055114:X-Ray Microtomography
microcomputed tomography; nickel-titanium instruments; reciprocating motion; root canal preparation; single-file system