Electronic Thesis and Dissertation Repository

Degree

Master of Clinical Dentistry

Program

Orthodontics

Supervisor

Tassi, A.

Abstract

Background: Resistance to tooth movement is multifactorial, with friction (FR) one of many important components. There is limited data comparing contemporary Passive and Active self-ligating bracket (SLB) systems in terms of FR created by archwire engagement. Aim: To compare classical FR in contemporary SLB systems and traditional twin brackets in vitro, and to identify the point of initiation of bracket-archwire engagement. Materials & Methods: Nine bracket systems of .022-in slot size were FR tested: Victory Series (3M Unitek) with elastic ligature (control); Passive SLB systems Damon Q (Ormco), Carriere SLX (Henry Schein), H4 (Ortho Classic), Altitude SL (Rocky Mountain Orthodontics, RMO), and Empower2 Passive (American Orthodontics, AO); Active SLB systems Victory Series SL (3M Unitek), Speed (Speed System Orthodontics), and Empower2 Active (AO). Single upper right central incisor brackets were mounted on a custom metal fixture and straight sections of various round and rectangular Nickel Titanium (NiTi) archwires (.016, .018, .018 x .018, .020 x .020, .016 x .022, .017 x .025, .019 x .025, and .021 x .025-in) were ligated to the bracket and FR was measured with an Instron Universal Testing Machine. Ten unique tests utilizing a new bracket and new archwire were conducted for each group in the dry state. Results: FR was significantly different between control, Passive SLB and Active SLB systems (p < 0.0001). Passive SLB groups had no mean difference of FR between bracket systems. Each Active SLB group exhibited significant mean differences in FR depending on the bracket system and archwire shape and dimension. Active SLBs possess a distinctly different pattern of initiation of FR engagement between bracket and archwire depending on the system. Conclusions: FR between the archwire and bracket slot differs between Passive and Active SLB systems. Understanding the different bracket-wire interactions of SLB systems helps the clinician understand and plan biomechanics with the bracket system of their choice.

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