Comparative evaluation of shaping ability of EdgeOne-R Utopia, One Reci, and WaveOne Gold in severely curved simulated root canals: an in vitro study

The preparation of severely curved root canals is challenging and may result in procedural errors and undesirable changes in canal geometry. Thermally treated nickel–titanium instruments have been developed to improve flexibility and shaping performance in curved canals. This study aimed to evaluate and compare the shaping ability of three single-file systems with reciprocating motion, EdgeOne-R Utopia, One Reci, and WaveOne Gold, in severely curved simulated root canals by assessing canal enlargement and canal transportation. Forty-five L-shaped resin root canal models with a 40° apical curvature, a 0.02 taper, and a 0.15-mm apical diameter were allocated to three groups ( n = 15 each), with each group prepared using one of the following systems: WaveOne Gold, One Reci, and EdgeOne-R Utopia. All systems were operated in reciprocating motion. Pre- and postoperative images were superimposed to assess canal enlargement and canal transportation using image-analysis software. Data were analyzed using paired-samples t-tests, the Kruskal–Wallis test, and one-way ANOVA followed by Tukey’s post hoc test where applicable ( p < 0.05). WaveOne Gold produced the greatest enlargement in the middle and coronal thirds, whereas One Reci produced the least in the apical third ( p < 0.001). Overall enlargement was greatest with WaveOne Gold, intermediate with EdgeOne-R Utopia, and lowest with One Reci ( p < 0.001). Canal transportation did not differ significantly among the systems in the apical, middle, or coronal regions ( p = 0.061, p = 0.843, and p = 0.820, respectively). All systems removed significantly more resin from the outer than the inner wall in the coronal region ( p < 0.001), with no significant inner–outer differences in the apical or middle regions. In severely curved simulated canals, the three systems showed comparable canal transportation, with the coronal region being the only region showing a consistent outward tendency across all systems. The systems differed in the degree of canal enlargement, with One Reci producing the lowest overall enlargement.