Cutting efficiency and dentinal defects using two single-file continuous rotary nickel–titanium instruments

Abstract

Aim: The aim of this study was to evaluate and compare the cutting efficiency and dentinal defect rates using two single-file continuous rotary nickel–titanium instruments. Materials and Methods: Thirty-two resin endo training blocks and 48 mesiobuccal roots of extracted human first lower molars were divided into five groups (16 for each group). Roots were checked for the homogeneities of root canal dimensions, thickness of dentin walls, and curvatures using images of X-ray radiographs on AUTOCAD software. Two groups of resin blocks and two groups of mesiobuccal canals were instrumented using two continuous rotary nickel–titanium instruments (Neoniti A1 and OneShape), the remaining group (control group) of mesiobuccal canals was left intact. The cutting efficiencies of instruments were quotients of the loss weights of specimens, and the time needed for instrumentation. ANOVA and post hoc Tukey tests were used to analyze the differences among the experimental groups. The cracks on the sectioned root surfaces at 3-, 6-, and 9-mm levels were recorded. Fisher exact test was used to analyze the differences among the experimental groups. Results: Cutting efficiency of OneShape was greater than that of Neoniti on both resin and human root canals (P 0.05). Conclusions: OneShape instrument was more efficient than Neoniti on both kinds of root canals. Both instruments created dentinal defects on root canal walls.