The European Journal of Orthodontics Advance Access originally published online on October 1, 2009
The European Journal of Orthodontics 2009 31(6):643-646; doi:10.1093/ejo/cjp054
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In vitro evaluation of the frictional forces between brackets and archwire with three passive self-ligating brackets
* Department of Orthodontics, University of Messina
** Department of University of Milano
*** Department of University of Chieti, Italy
Address for correspondence Giampietro Farronato, Department of Orthodontics, University of Milano, Via Della Commenda 10, 20122 Milano, Italy, E-mail: giampietro.farronato{at}unimi.it
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Abstract |
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The aim of this in vitro study was to evaluate the frictional forces between bracket and archwire that included three passive self-ligating brackets (Damon SL2 SDS). The brackets were individually bonded to a brass mount using a preformed 0.021 x 0.025 inch stainless steel wire jig in order to exclude adverse tipping or torsion. The central bracket was positioned 1 mm higher than the others, in order that the three brackets were vertically unaligned. Thirty-six similar set-ups including in total 108 brackets were investigated using the same wire: copper (nickel–titanium) 0.014 inches. A testing machine was designed and constructed to measure the frictional forces between the wire and the three-bracket set-up. Twelve set-ups were tested to measure kinetic frictional forces between the wire and unaligned passive self-ligating brackets used in the closed position. The frictional properties of two sets of 12 three-bracket set-ups (control) were tested and measured with an open slide and conventional ligation. A stainless steel ligature wire was used in the former, while elastomeric modules were employed in the latter.
One-way analysis of variance showed a significant effect of ligation mode on the frictional properties of the three-bracket set-ups (P < 0.001). Post hoc pairwise comparison showed that the frictional forces arising from passive self-ligation were significantly lower (P < 0.01) than those resulting from elastic ligation. The same result was achieved when comparing self-ligation and metallic ligation (P < 0.01). No significant difference was found when comparing elastic and metallic ligation.