A comparison of torque expression between stainless steel, titanium molybdenum alloy, and copper nickel titanium wires in metallic self-ligating brackets

The force moment providing rotation of the tooth around the x-axis (buccal-lingual) is referred to as torque expression in orthodontic literature. Many factors affect torque expression, including the wire material characteristics. This investigation aims to provide an experimental study into and com...

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Published inThe Angle orthodontist Vol. 80; no. 5; pp. 884 - 889
Main Authors Archambault, Amy, Major, Thomas W, Carey, Jason P, Heo, Giseon, Badawi, Hisham, Major, Paul W
Format Journal Article
LanguageEnglish
Published United States Edward H Angle Education and Research Foundation, Inc 01.09.2010
Subjects
Alloys - chemistry
Copper - chemistry
Dental Alloys - chemistry
Dental Stress Analysis - instrumentation
Humans
Materials Testing
Nickel - chemistry
Original
Orthodontic Appliance Design
Orthodontic Brackets
Orthodontic Wires
Rotation
Stainless Steel - chemistry
Stress, Mechanical
Surface Properties
Temperature
Titanium - chemistry
Torque
Torsion, Mechanical
Transducers
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Summary:The force moment providing rotation of the tooth around the x-axis (buccal-lingual) is referred to as torque expression in orthodontic literature. Many factors affect torque expression, including the wire material characteristics. This investigation aims to provide an experimental study into and comparison of the torque expression between wire types. With a worm-gear-driven torquing apparatus, wire was torqued while a bracket mounted on a six-axis load cell was engaged. Three 0.019 x 0.0195 inch wire (stainless steel, titanium molybdenum alloy [TMA], copper nickel titanium [CuNiTi]), and three 0.022 inch slot bracket combinations (Damon 3MX, In-Ovation-R, SPEED) were compared. At low twist angles (<12 degrees), the differences in torque expression between wires were not statistically significant. At twist angles over 24 degrees, stainless steel wire yielded 1.5 to 2 times the torque expression of TMA and 2.5 to 3 times that of nickel titanium (NiTi). At high angles of torsion (over 40 degrees) with a stiff wire material, loss of linear torque expression sometimes occurred. Stainless steel has the largest torque expression, followed by TMA and then NiTi.
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Professor of Orthodontics, School of Dentistry, University of Alberta, Edmonton, AB Canada
Graduate MSc student, Orthodontic Graduate Program, School of Dentistry, University of Alberta, Edmonton, AB Canada
Assistant Professor of Statistics, School of Dentistry, University of Alberta, Edmonton, AB Canada
Associate Professor, Department of Mechanical Engineering, University of Alberta, Edmonton, AB Canada
Research Assistant, Orthodontics Biomechanics Research Lab, School of Dentistry, University of Alberta, Edmonton, AB Canada
Associate Clinical Professor of Orthodontics, School of Dentistry, University of Alberta, Edmonton, AB Canada
ISSN:0003-3219
1945-7103
DOI:10.2319/102809-604.1