The instrument-centering ability of four Nickel-Titanium instruments in simulated curved root canals

Abstract

The aim of this study was to evaluate the ability of newly marketed NRT instruments to maintainthe original root canal configuration and curvature during preparation in comparison with the threeexisting instruments in simulated root canals. Simulated canals in resin blocks were prepared with ProFile, K3, ProTaper, and NRT instrument(n = 10 canals in each case). Pre- and post-operative images were recorded, and assessment ofcanal shape was completed with a computer image analysis program. The data were analyzed statis-tically using the One-way ANOVA followed by Duncan’s test.The ability of instruments to remain centered in prepared canals at 1-, 2-㎜levels was significantlybetter in ProFile groups than in other groups (p < 0.05). The change of centering ratio in NRTgroups at 5-㎜level was significantly greater than ProFile group and at 6- and 7-㎜level than allother groups (p < 0.05).Although the NRT system was comparable to other systems in regards to its ability to maintain thecanal configuration of apical portion, this system was more influenced by the mid-root curvature dueto its stainless-steel files for coronal preflaring.