The European Journal of Orthodontics Advance Access published online on November 21, 2008
The European Journal of Orthodontics, doi:10.1093/ejo/cjn053
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Conventionally ligated versus self-ligating metal brackets—a comparative study
* Department of Orthodontics, Regensburg University Medical Center
** Department of Orthodontics, Preventive and Pediatric Dentistry, Medical Center, Ernst Moritz Arndt University of Greifswald
*** Private Practice, Munich, Germany
**** Private Practice, Linz, Austria
Address for correspondence, C. A. Reicheneder, Department of Orthodontics, Medical Center, University of Regensburg, Franz-Josef-Strauss-Allee, 93053 Regensburg, Germany, E-mail:claudia.reicheneder{at}gmx.net
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Abstract |
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The purpose of this study was to compare the frictional properties of four self-ligating metal brackets, Speed, Damon 2, In-Ovation, and Time, with those of three conventionally ligated metal brackets, Time, Victory Twin, and Discovery. The self-ligating Time bracket can also be used as a conventionally ligated bracket. Friction was tested 20 times for each bracket/wire combination using a Zwick testing machine with stainless steel wires in three different wire dimensions (0.017 x 0.025, 0.018 x 0.025, and 0.019 x 0.025 inches). All brackets had a 0.022 inch slot and the prescription of an upper first premolar. The data were statistically analysed with unsigned comparisons of all bracket/wire combinations using the Mann–Whitney U-test and the Games–Howell post hoc test.
The results showed almost all brackets to have the lowest frictional force with a wire dimension of 0.018 x 0.025 inch. Friction of the self-ligating brackets using wire with a dimension of 0.018 x 0.025 inches was 45–48 per cent lower than with 0.017 x 0.025 and 0.019 x 0.025 inch wires. Friction of the conventionally ligated brackets showed a 14 per cent or less reduced friction with 0.018 x 0.025 inch wire compared with 0.017 x 0.025 and 0.019 x 0.025 inch wires. The self-ligating metal brackets showed lower frictional forces with a 0.018 x 0.025 inch wire than conventionally ligated brackets, whereas conventionally ligated brackets showed lower friction with 0.017 x 0.025 and 0.019 x 0.025 inch wire.
Friction values vary with different bracket/archwire combinations and, therefore, the choice of a bracket system for treatment should consider the correct wire dimension to produce the lowest possible frictional forces.