Torque and force induced by ProTaper universal and ProTaper next during shaping of large and small root canals in extracted teeth.
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.
['Arias|Ana|A|', 'Singh|Rupinderpal|R|', 'Peters|Ove A|OA|']
D003786:Dental Pulp Cavity D004867:Equipment Design D004868:Equipment Failure D006801:Humans D007180:Incisor D008422:Materials Testing D008855:Microscopy, Electron, Scanning D008963:Molar D011897:Random Allocation D018915:Root Canal Preparation D013314:Stress, Mechanical D019227:Tooth Apex D019415:Torque
torque ProTaper Universal ProTaper Next M-Wire