Load deflection characteristics and force level of nickel titanium initial archwires

Abstract

Objectives: To investigate and compare the characteristics of commonly used types of traditional and heat-activated initial archwire by plotting their load/deflection graphs and quantifying three suitable parameters describing the discharge plateau phase. Materials and Methods: Forty-eight archwires (22 nickel titanium [NiTi] and 26 heat-activated) of cross-sectional diameter ranging from 0.010 to 0.016 inch were obtained from seven different manufacturers. A modified three-point wire-bending test was performed on three analogous samples of each type of archwire at a constant temperature (37.0uC). For each resulting load/ deflection curve, the plateau section was isolated, along with the mean value of the average plateau force, the plateau length, and the plateau slope for each type of wire obtained. Results: Statistically significant differences were found between almost all wires for the three parameters considered. Statistically significant differences were also found between traditional and heat-activated archwires, the latter of which generated longer plateaus and lighter average forces. The increase in average force seen with increasing diameter tended to be rather stable, although some differences were noted between traditional and heat-activated wires. Conclusions: Although great variation was seen in the plateau behavior, heat-activated versions appear to generate lighter forces over greater deflection plateaus. On average, the increase in plateau force was roughly 50% when the diameter was increased by 0.002 inch (from 0.012 to 0.014 and from 0.014 to 0.016 inch) and about 150% when the diameter was increased by 0.004 inch (from 0.012 to 0.016), with differences between traditional and heat-activated wires noted in this case. (Angle Orthod. 2012;82:507-521.)

Influences of archwire size and ligation method on the force magnitude delivered by nickel-titanium alloy archwires in a simulation of mandibular right lateral incisor linguoversion

“…This result is close to the previous study that reported approximately 50% of increases in force magnitude by increasing 0.002 inch of archwire size 13) . Furthermore, the present study also found that the mean force magnitude at 41 increased by 76% to 140%, and the mean force magnitude at 31 increased by 55% to 88%.…”

“…The following factors are thought to affect the force magnitude at each tooth: the ligation method used for the archwire [6][7][8][9][10][11][12] ; the diameter of the archwire 13) ; and the inter-bracket distance 7) .…”

“…Recently, force magnitudes of nickel-titanium alloy archwires with different ligation methods have been compared using a modified three-point bending test. Brackets were bonded to a metal block [6][7][8] or resin formed model 9,13) and the force from the ligated and deflected nickel-titanium alloy archwires were measured at a single point. Significant differences in the force magnitude from the archwire were found when using a stainless steel ligature, elastic module, and the self-ligating method [6][7][8]13) .…”

“…However, the selection of an archwire and archwire size depends on the type of the patient's original malocclusion, the clinician's educational background, and the appliance system being used. Although variation exists, Lombardo et al 13) compared the force magnitude of 5 sizes of nickel-titanium alloy round archwires and observed an approximately 50% increase in the force magnitude when the diameter increases 0.002 inch. Since they measured the force at a point of an archwire, the magnitude of force at several different points as force delivery could not be clarified.…”

Avaliação da força gerada pela deflexão gradual de fios ortodônticos em braquetes convencionais metálicos, estéticos e autoligáveis

“…Portanto, é de maior interesse clínico conhecer as forças liberadas pelo teste de descarga do que as forças liberadas pelo teste de carga (CHEN;ZHI;ARVYSTAS, 1992;FISCHER-BRANDIES et al, 2003;MURAVIEV;OSPANOVA;SHLYAKHOVA, 2001;WATERS, 1992b;YONEYAMA et al, 1992), uma vez que a descarga representa as forças que promovem a movimentação dentária durante o tratamento ortodôntico (ANDREASEN; HEILMAN;KRELL, 1985;BARTZELA;WICHELHAUS, 2007;WARAM, 2007;BURSTONE;QIN;MORTON, 1985;TAVERNIER;JORDAN, 2005;GATTO et al, 2013;KAPILA et al, 1991;LIAW et al, 2007;LOMBARDO et al, 2012;MURAVIEV;OSPANOVA;SHLYAKHOVA, 2001;NAKANO et al, 1999;SEGNER;IBE, 1995;VAN AKEN et al, 2008). Adicionalmente, a norma ISO 15.841 também indica a avaliação dos resultados em descarga.…”