This study was conducted to evaluate canal configuration after shaping by ProTaper™ with various rotational speed in J-shaped simulated resin canals.

Forty simulated root canals were divided into 4 groups, and instrumented using by ProTaper™ at the rotational speed of 250, 300, 350 and 400 rpm. Pre-instrumented and post-instrumented images were taken by a scanner and those were superimposed. Outer canal width, inner canal width, total canal width, and amount of transportation from original axis were measured at 1, 2, 3, 4, 5, 6, 7 and 8 mm from apex. Instrumentation time, instrument deformation and fracture were recorded. Data were analyzed by means of one-way ANOVA followed by Scheffe's test.

The results were as follows

Regardless of rotational speed, at the 1~2 mm from the apex, axis of canal was transported to outer side of a curvature, and at 3~6 mm from the apex, to inner side of a curvature. Amounts of transportation from original axis were not significantly different among experimental groups except at 5 and 6 mm from the apex.

In conclusion, the rotational speed of ProTaper™ files in the range of 250~400 rpm does not affect the change of canal configuration, and high rotational speed reduces the instrumentation time. However, appearance of separation and distortion of Ni-Ti rotary files can occur in high rotational speed.