Introduction: This study aimed to evaluate the central ability and root canal transportation of two types of rotary files in curved molar canals using cone-beam computed tomography (CBCT) in mesiodistal (MD) and buccolingual (BL) directions.

Method and Material: A total of 40 mesiobuccal root canals of mandibular first molars with an angle of 25-35 degrees and radius curvature of 5 millimeters were randomly divided into two groups of 20 canals each. Group A was prepared with Pro Taper Gold (PTG), and Group B with V Taper Gold (VTG). Pre- and post-instrument CBCT scans were recorded. Images were reconstructed, then cross-sections were detected corresponding to distances of 3, 6, and 9 mm from the anatomic apex using Gambill’s method. Statistical analysis was performed with T-test and repeated measure ANOVA. P-value was set at 0.05.

Results: There was a significant difference in centering ratio and canal transportation at all three levels of 3-, 6-, and 9- mm, mesiodistally. PTG has higher centering ability in 6 mm and 9 mm sections with more canal transportation at 3 mm and 6 mm.

In the BL direction, no statistically significant difference in central ability was observed among the PTG and VTG groups. The centering ability of both groups became higher from the apex to the coronal part. The last and the most canal transportation in both PTG and VTG groups was reported at 6 mm level and 9 mm level, respectively.

Conclusion: Both rotary instruments efficiently cleaned and shaped curved canals. ProTaper Gold had better centering ability, while V Taper Gold showed less canal transportation.