Related Experiment Video
Updated: May 31, 2026

Method to Measure Tone of Axial and Proximal Muscle
Published on: December 14, 2011
Effect of lateral pressure motion on the torsional behavior of rotary ProTaper Universal instruments
Evandro Pires Vieira1, Vicente Tadeu Lopes Buono, Maria Guiomar de Azevedo Bahia
1Department of Restorative Dentistry, Faculty of Dentistry, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Minas Gerais, Brazil.
Introduction:
The purpose of this study was to evaluate the torsional behavior of rotary ProTaper Universal instruments after multiple clinical uses with and without lateral pressure motion.
Methods:
Thirty sets of ProTaper Universal instruments were divided into 3 groups (n = 10): control group (CG) involving new instruments tested in torsion on the basis of ISO 3630-1, lateral pressure (LP) group involving instruments that were clinically used on 5 molars by using the shaping instruments S1 and S2 with lateral pressure motion, and no lateral pressure (NLP) group involving instruments that were clinically used on 5 molars without lateral pressure motion. The instruments in the LP and NLP groups were subsequently tested in torsion. Data were analyzed by using analysis of variance (α = 0.05).
Results:
Multiple clinical uses caused a reduction in the maximum torque in the analyzed instruments. When the effect of using lateral pressure motion with the shaping instruments was assessed, a tendency of reduction in the maximum torque for the S1 and S2 instruments and of increase for the F1 and F2 instruments was observed in the group with lateral pressure motion.
Conclusions:
The use of lateral pressure motion with the shaping instruments S1 and S2 tended to produce smaller decreases in the torsional resistance of the finishing instruments F1 and F2.
More Related Videos
Related Concept Videos
Deformation in a Circular Shaft
Thin-Walled Hollow Shafts
Torsion of Noncircular Members
Stress Concentrations in Circular Shafts
Residual Stresses in Circular Shafts
Bending and Torsional Moments
The reaction developed in a structural element when subjected to an external force causes the element to bend. When a structural element bends upwards, it creates compressive normal forces on the top and tensile normal forces on the bottom, resulting in a couple that determines the bending...

