Comparison of the centring ability of the ProTaper™ and ProTaper Universal™ rotary systems for preparing curved root canals.

The aim of this in vitro study was to compare the centring ability of the ProTaper™ and ProTaper Universal™ rotary systems for preparing curved root canals, by means of preoperative and postoperative imaging of a cross-section of their coronal, middle and apical thirds. Twenty mesiobuccal root canals of human mandibular first molars with a degree of curvature ranging from 55° to 60° were randomly divided into two groups of 10 specimens each: Group 1, ProTaper™ rotary system; and Group 2, ProTaper Universal™ rotary system. The data were analysed statistically by Kruskal-Wallis and Student's t-test at the 5% significance level.