Comparison of Canal Transportation and Changes in Canal Curvature of Two Nickel-Titanium Rotary Instruments

Introduction: The aim of this study was to compare the canal transportation and changes in canal curvature after canal preparation with 2 nickel-titanium (NiTi) rotary instruments, Twisted (TF) and K3 file systems. Methods: Forty mandibular molar canals with angles of curvature between 25 and 35 degrees were randomly divided into 2 groups. Canals in K3 group were instrumented by using K3 rotary system. Canals in TF group were instrumented by using IF rotary system. All canals were instrumented with crown-down methodology to working length at a speed of 350 rpm and a torque-control level of 3 by using an 8:1 reduction handpiece. The final apical preparation was set to #30 in both groups. By using a radiographic platform, reproducible preinstrumentation and postinstrumentation radiographs were taken. The difference between the preinstrumentation and postinstrumentation angles was calculated and statistically analyzed by using unpaired t test. Results: TF recorded statistically significant lower percentage of change in canal curvature (-2.99%) than K3 group (P < .05). Conclusions: TF system produced significantly less transportation and preserved the original canal to a greater degree than did the K3 system. (J Endod 2011;37:1290-1292)