Defense Date


Document Type


Degree Name

Master of Science



First Advisor

Dr. B. Ellen Byrne


Rotary endodontic instruments have different cross sectional designs that may effect their resistance to torsional stress. The purpose of this study is to evaluate the static torsional properties of two nickel titanium files that have recently been introduced for use in endodontics and compare them to the same size Profile instruments. Ten new files of each brand and size were tested. The files tested were: RaCe 25 tip 0.02, 0.04, 0.06 taper, K3 and Profile 25 and 40 tip in 0.02, 0.04 and 0.06 taper. The diameter of each file was measured at 3mm from tip. The last three millimeters of the working area of the file was grasped with a non-rotating stainless steel chuck and the handle was held in freely rotating chuck. Torque was applied with the Instron Universal Tester in a counter-clockwise direction to simulate the direction of torque encountered clinically. The crosshead speed was set to produce 2 rotations per minute until fracture occurred. The maximum torque achieved and the rotations to fracture were recorded. A multi-way ANOVA of rotations revealed that RaCe 25-0.02 exhibited significantly less rotations to fracture than Profile and K3 of the same size (p<0.0001). RaCe 25 tip exhibited lower maximum torque in all tapers than corresponding K3 and Profile instruments. The mean diameter was significantly smaller for the RaCe files. In this study the RaCe file series exhibited lower values for maximum torque and rotations to fracture. These results should be taken into account while using these files clinically, however further testing is indicated.


© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

June 2008