Influence of Friction Resistance on Expression of Superelastic Properties of Initial NiTi Wires in “Reduced Friction” and Conventional Bracket Systems

Natalie Reznikov; Gilad Har-Zion; Idit Barkana; Yosef Abed; Meir Redlich

doi:10.4061/2010/613142

Influence of Friction Resistance on Expression of Superelastic Properties of Initial NiTi Wires in “Reduced Friction” and Conventional Bracket Systems

Natalie Reznikov naoree{at}gmail.com¹
Gilad Har-Zion gilad9{at}012.net.il²
Idit Barkana iditbarkana{at}yahoo.com²
Yosef Abed abedy{at}cc.huji.ac.il²
Meir Redlich mredlich{at}bezeqint.net²

¹Faculty of Dental Medicine, Hadassah-Hebrew University, P.O. Box 12272, 91120 Jerusalem, Israel
²Department of Orthodontics, Faculty of Dental Medicine, Hadassah-Hebrew University, P.O. Box 12272, 91120 Jerusalem, Israel

Abstract

Objectives. The aim of this study was to assess the influence of resistance to sliding on expression of superelastic properties of NiTi wires.

Methods and Materials. A three-point bending test was performed for 0.014 NiTi wire engaged in self-ligating (Damon, SmartClip, In-Ovation) and conventional brackets (Victory) ligated with regular and reduced friction modules (Slide). The wire was deflected in the buccal direction and allowed to straighten. The maximum load, unloading plateau and unloading capacity were registered.

Results. The lowest activation load was required in the active self-ligating group (In-Ovation $\text{[math]}$ N) and reduced friction module group (Victory/Slide $\text{[math]}$ N), followed by the passive self-ligating systems (Damon $\text{[math]}$ N, SmartClip $\text{[math]}$ N). Higher activation load was obtained in the conventionally ligated group (Victory/module $\text{[math]}$ N). Unloading plateau phase with the load magnitude ranging from $\text{[math]}$ N (In-Ovation) to $\text{[math]}$ N (Slide) was distinct in all groups but one (Victory).

Conclusions. Higher friction at flanking points reduces the net force delivered by the wire. Unloading plateau phase of NiTi load-deflection curve disappears in the conventionally ligated group thus indicating to an incomplete expression of NiTi superelastic properties. A rigid passive bracket clip amplifies resistance to sliding in an active configuration and produces a permanent deflection of the wire.