Journal Article

The effect of ligation on the load–deflection characteristics of nickel–titanium orthodontic wire

Shugo Kasuya, Satoshi Nagasaka, Ai Hanyuda, Sadao Ishimura and Ayao Hirashita

in The European Journal of Orthodontics

Published on behalf of European Orthodontics Society

Volume 29, issue 6, pages 578-582
Published in print December 2007 | ISSN: 0141-5387
Published online September 2007 | e-ISSN: 1460-2210 | DOI: http://dx.doi.org/10.1093/ejo/cjm068
The effect of ligation on the load–deflection characteristics of nickel–titanium orthodontic wire

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This study examined the effect of ligation on the load–deflection characteristics of nickel–titanium (NiTi) orthodontic wire. A modified three-point bending system was used for bending the NiTi round wire, which was inserted and ligated in the slots of three brackets, one of which was bonded to each of the three bender rods. Three different ligation methods, stainless steel ligature (SSL), slot lid (SL), and elastomeric ligature (EL), were employed, as well as a control with neither bracket nor ligation (NBL). The tests were repeated five times under each condition. Comparisons were made of load–deflection curve, load at maximum deflection of 2000 μm, and load at a deflection of 1500 μm during unloading. Analysis of Variance (ANOVA) and Dunnett's test were conducted to determine method difference (α = 0.05). The interaction between deflection and ligation was tested, using repeated-measures ANOVA (α = 0.05).

The load values of the ligation groups were two to three times greater than the NBL group at a deflection of 1500 μm during unloading: 4.37 N for EL, 3.90 N for SSL, 3.02 N for SL, and 1.49 N for NBL (P < 0.01). For the EL, a plateau region disappeared in the unloading curve. SL showed the smallest load. The ligation of the bracket wire may make NiTi wire exhibit a significantly heavier load than that traditionally expected. NiTi wire exhibited the majority of its true superelasticity with SL, whereas EL may act as a restraint on its superelasticity.

Journal Article.  2769 words.  Illustrated.

Subjects: Restorative Dentistry and Orthodontics

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