Related Experiment Video
Updated: Apr 28, 2026

Guided Endodontics: Three-Dimensional Planning and Template-Aided Preparation of Endodontic Access Cavities
Published on: May 24, 2022
Torque and force induced by ProTaper universal and ProTaper next during shaping of large and small root canals in
Ana Arias1, Rupinderpal Singh1, Ove A Peters1
1Department of Endodontics, Arthur A. Dugoni School of Dentistry, University of the Pacific, San Francisco, California.
Introduction:
The purpose of this study was to compare peak torque and force between ProTaper Universal (PTU) and ProTaper Next (PTN) instruments during the preparation of large and small root canals in extracted teeth.
Methods:
Twelve maxillary incisors and each independent canal of 6 mesial roots of mandibular molars were randomly assigned to be prepared with a new set of either PTU or PTN instruments after a glide path was achieved. A total of 12 new sets of each instrument system were used. The tests were run in a standardized fashion in a torque-testing platform. Peak torques (Ncm) and force (N) were registered; analysis of variance and Tukey post hoc tests were then applied.
Results:
Among instruments in the same sequence, no significant differences in peak torque and force were found among PTN instruments when shaping small or large root canals, but some PTU instruments showed statistically lower peak torque and force (P < .01) than others for both types of canals. Whereas PTU instruments showed significant differences in peak torque and force (P < .05) between large and small root canals, PTN instruments showed significantly lower force (P < .04) in large canals, but peak torque was not significantly different for upper central incisors or mesial mandibular root canals.
Conclusions:
Under the conditions of this study, instruments in ProTaper Next set showed greater regularity in peak torque for small and large canals than ProTaper Universal instruments.
Related Concept Videos
Tooth Anatomy
The Crown, Neck, and Root
The visible part of the tooth is referred to as the crown. It's covered by enamel, the hardest substance in the human body. The crown is uniquely shaped for each type of tooth, allowing for different functions such as cutting, tearing, or...
Net Torque Calculations
Torque
Torque can be considered as the rotational counterpart to force. Since forces change the translational...
Teeth
In the bud stage, the tooth germ (an aggregation of cells) starts to form in the developing jawbone. During the cap stage, the tooth germ differentiates into enamel organ, dental papilla, and dental sac, which will later develop into the tooth's enamel, dentin...

