Deformation of nickel-titanium closed coil springs: an in vitro study

Abstract

Objective: The aim of this paper was to determine the amount of deformation in four commercial brands of nickel-titanium closed springs. Methods: A total of 130 springs were divided into 13 subgroups, according to their features and manufacturers (Morelli, Orthometric, Ormco and GAC) and activated from 100% to 1000% of the effective length of the nickel-titanium portion present at the spring, at 37 °C. Deactivation data were plotted and deformation was found graphically. The values were compared by analysis of variance and Tukey's post-hoc test.Results: Springs manufactured by Morelli had the same amount of deformation when they were activated up to 700% of Y activation; springs by Orthometric had the same amount of deformation up to 600-700% of Y; springs by Ormco had the same amount of deformation up to 700-800% of Y; and finally, the majority of springs by GAC had similar deformation up to 800%-1000% of activation. All springs tested could be activated up to 700% without rupture.Conclusions:Most subgroups were similarly deformed up to 700% of activation, without rupture of springs. Subgroups 4B, 4C, 4D and 4E showed the same amount of deformation up to 1000% of activation without any rupture at all.

Effects of height and overactivation on a composite nickel-titanium T-loop

“…diminish [4,6,17,18] (Fig. 9) as occurred in this investigation, where overactivation of the loops produced lower forces.…”

“…6). Additionally, the beginning of the reverse transformation from the SIMT that occurs at the beginning of the deactivation in coil, or loop spring, produces a sudden drop in force before the previously mentioned pseudoplateau [4] (Fig. 1).…”

“…T-loops made of shape memory alloys will experience a stressinduced martensitic transformation (SIMT) and produce a pseudo-plateau 1 of force on deactivation, which allows greater activations without significant change of force during deactivation for en masse retraction [3]. However, the load-deflection graph of a nickel-titanium material that underwent SIMT displays a characteristic shape on unloading and a sudden drop of force when the load is removed before the pseudo-plateau is reached [4] (Fig. 1).…”

Effects of reversing the coiling direction on the force-deflection characteristics of nickel-titanium closed-coil springs

“…The force-deflection characteristics of the two conventional NiTi-CCS groups were not significantly different from those of previous studies 16716181920. The force levels of the DFPs of the Ormco- and GAC-Conventional groups were 1.2 and 1.1 N, respectively (Table 2), which are almost the same as the results of Vieira et al16 (1.1 N for Ormco light NiTi-CCS; 1.0 N for GAC light NiTi-CCS).…”

An In Vitro Comparison of the Forces Released by Closed Nickel–Titanium Springs

“…There are probably molecular differences in the alloys of the springs, and analyses with graphs of phase transformation of the crystallographic structure of the nickel-titanium alloys between the martensitic and austenitic phases have been suggested to explain the behavior of the alloy of each of the springs. [18][19][20][21] As a clinical consideration of the study, the results obtained in the present research are relevant to the use of nickel-titanium closed springs with regard to the quantity of force released during the mechanics of space closure after extraction (main application of nickel-titanium closed springs), and to the pattern of forces released by springs in view of the real context of gradual closure of spaces after tooth extractions.…”