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The effects of stainless steel ligature ties on the mechanical characteristics of conventional and self-ligated brackets subjected to torque Open Access


Other title
bracket deformation
stainless steel ligature
Type of item
Degree grantor
University of Alberta
Author or creator
Al Fakir, Hussam
Supervisor and department
Paul Major (Department of Dentistry)
Examining committee member and department
David Nobes (Mechanical Engineering)
Jason Carey (Mechanical Engineering)
Paul Major (Department of Dentistry)
Giseon Heo (Department of Dentistry)
Medical Sciences-Dentistry
Date accepted
Graduation date
Master of Science
Degree level
Stainless steel ligatures ties are routinely used by orthodontists to improve torque; nevertheless, there is a lack of evidence as to the role of stainless steel ligation in bracket retentive characteristics. The objective of this study is to look into the effects of stainless steel (SS) ligation has on torque and bracket deformation for conventional and self-ligated brackets. A previously described torquing apparatus, combined with an overhead camera, utilized to rotate a .019x.025-inch stainless steel wire in a bracket slot to measure torque (Nmm) and acquire an overhead image at 3° increments of wire rotation from 0° up to 45°, and back again to 0°. A digital image correlation means and two profile images comparisons (before and after) were used to assess the structural changes of the bracket throughout the wire rotation and after the experiment, respectively Sixty Orthos®Twin brackets (Ormco Corp., Glendora, CA, USA), 30 ligated with conventional elastic ties and 30 ligated with SS ligature ties, and sicty Damon Q® brackets (Ormco Corp., Glendora, CA, USA), 30 ligated with its conventional sliding door and 30 ligated with SS ties in addition to the sliding door, were used. The torque was significantly higher for the steel ligated groups over conventional ones from 3°-9° of wire rotation. Overall, steel ligation did increase torque for Orthos twin brackets but it did not for Damon Q brackets. Stainless steel ligature reduces the amount of plastic deformation of both Orthos twin and Damon Q brackets, and a slight decrease in the slot width can be evident when stainless steel ligature is first applied to a bracket. SS ligature ties can be an effective auxiliary tool that could help practitioners to achieve better torque and to reduce bracket deformation
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
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File title: Alfakir_Hussam_Spring2012
File author: Hussam Fakir
Page count: 117
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