Comparison of Cutting Efficiency and Safety of 10/0.04 RaCe and Mtwo Rotary File Systems in Reaching the Full Root Canal Working Length: An In Vitro Study

Introduction: Both RaCe and Mtwo rotary systems introduced the 10/0.04 file as the first file used in the root canal (Glide path). This study aims to compare different factors of both the rotary systems, including cutting efficacy, file fracture, topography changes of files, and changes of the root canal. Materials and Methods: In this laboratory study, 12 RaCe and 12 Mtwo files were prepared and tested on 24 resin blocks with 30° curvature. The time to reach the working length was recorded. Topographical changes of the files have been observed with a stereomicroscope if needed. Changes in resin blocks were measured by photographing and using Photoshop software. Data were analyzed through an independent two-sample t test and likelihood-ratio chi-squared test. Results: Time to reach the working length was significantly lower in the RaCe group than in the Mtwo group (3.57 ± 0.56 s vs. 10.33 ± 2.25 s, P < 0.001). File fracture did not occur in any of the two rotary systems. Topographical changes of the files in RaCe group were also less than the Mtwo group (P = 0.032). Conclusion: The RaCe file is faster in reaching the working length. Both files are safe and do not cause drastic changes in the root canal.