Comparison of Torque, Screw-in Force, and Shaping Ability of Glide Path Instruments in Continuous Rotation and Optimum Glide Path Motion

J Endod. 2021 Jan;47(1):94-99. doi: 10.1016/j.joen.2020.09.013. Epub 2020 Sep 28.


Introduction: This study aimed to analyze torque/force generation and transportation in double-curved canals instrumented with 3 types of glide path files using optimum glide path (OGP) motion in comparison with continuous rotation.

Methods: Sixty simulated double-curved canals were prepared with #10/0.05 or #15/0.03 HyFlex EDM Glidepath files (Coltene/Whaledent, Altstätten, Switzerland) or a #13/0.04 prototype MANI Glidepath file (Tochigi, Japan) using OGP motion or continuous rotation (n = 10 each). Canals were sequentially prepared to 20 mm and 22 mm (full working length) using automated root canal instrumentation and a torque/force analyzing device. Transportation was calculated at 1-9 mm from the apex. Data were compared using 2-way analysis of variance followed by a post hoc simple main effect test with Bonferroni correction and a Kruskal-Wallis test (α = 5%).

Results: All #10/0.05 instruments fractured. In the 22-mm preparation, the OGP motion resulted in lower clockwise torque and screw-in force than did continuous rotation (P < .05). In the 20-mm preparation, #15/0.03 instruments recorded a lower screw-in force for OGP motion than for continuous rotation (P < .05). Comparing the 2 preparation phases, OGP motion generated no significant differences; however, continuous rotation developed higher clockwise torque and screw-in force in the 22-mm preparation than in the 20-mm preparation (P < .05). There was no significant difference among the tested groups for transportation values.

Conclusions: Compared with continuous rotation, OGP motion generated less screw-in force, lower clockwise torque, and similar transportation. The #15/0.03 HyFlex EDM instrument and the #13/0.04 prototype MANI instrument performed similarly well.

Keywords: Continuous rotation; glide path; optimum glide path motion; screw-in force; torque.

MeSH terms

  • Bone Screws*
  • Dental Instruments
  • Dental Pulp Cavity
  • Equipment Design
  • Root Canal Preparation*
  • Rotation
  • Titanium
  • Torque


  • Titanium