Comparative Evaluation of Canal Transportation and Centering Ability of Various Ni-Ti Rotary Systems in Retreatment of Curved Root Canals

Abstract

Background: The aim of the present study was to evaluate the canal transportation and centering ability of ProTaper, HeroShaper and two Ni-Ti rotary systems developed for retreatment ProTaperRetreatment and R-Endo. Methods: One hundred twenty mesial canals of mandibular molars with curvatures between 30-40 degrees and radii of curvatures between 4-9 mm were embedded in a modified muffle system. The teeth were randomly divided into 8 groups (n=15). The roots were sectioned horizontally at 3, 6 and 9 mm from the working length. Cross-sections were digitally photographed under standardized conditions. Half of the root canals were prepared with ProTaper and the rest with HeroShaper. Postoperative photographs were obtained. Root canals were obturated with the respective guttapercha cones of the systems and AHPlus sealer. Following retreatment with four systems, photographs were assessed for the canal transportation in 8 directions, and centering ratio. The data were analyzed with Friedman test for repeated measurements, Kruskal Wallis test for intergroup comparisons and Dunn's multiple comparison test for subgroup comparisons, and significance was set at P < 0.05. Results: Initial shaping with ProTaper resulted in more significant transportation than HeroShaper (p<0.05). After retreatment, REndo yielded negative transportation values in the apical and midsections. In canals prepared with ProTaper, in the apical and coronal root sections ProTaperRetreatment, and in the midsections ProTaper revealed more acceptable re-shaping results. In the canals prepared with HeroShaper, after retreatment, transportation and centering ability were relatively efficient with HeroShaper in the apical and mid-sections; and with ProTaper in the coronal sections. Conclusion: All systems caused a certain amount of transportation and eccentricity. Protaper, ProtaperRetreatment and HeroShaper showed similar re-shaping performance with regard to the initial shaping procedure. However, R-Endo yielded insufficient root canal cleaning in the apical and mid-sections. © 2022, Selcuk University. All rights reserved.