Mechanical behavior and clinical application of nickel-titanium closed-coil springs under different stress levels and mechanical loading cycles

Wichelhaus, Andrea; Brauchli, Lorenz; Ball, Judith; Mertmann, M.

doi:10.1016/j.ajodo.2008.06.029

Cited by 32 publications

(47 citation statements)

References 9 publications

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“…It has been shown that the initial activation length of NiTi coil springs can have a significant influence on their force properties and effects both the length and absolute value of the constant force plateau regions of these springs. 23 However, an interesting finding of these studies that is in concordance with our results is that GAC NiTi springs do not exhibit constant force of the reported 150gm over the entire 12mm activation range as claimed by the manufacturer. 5, 16, 22 The super-elastic force plateau region occurs over a much more limited range than advertised.…”

Section: Discussionsupporting

confidence: 91%

“…18 Our findings agree with Wichelhaus, who demonstrated via in vitro thermo-cycling and mechanical micro-cycling tests, that the oral environment does not seem to be a major influence on the mechanical properties of NiTi coil springs. 23 Additionally, NiTi coil springs have been shown by Nattrass et al to be unaffected in vitro by the specific environmental factors of water, Coke ®, or turmeric solution. 24 The biggest difference between the in vivo and in vitro environments that seems to concern researchers with respect to NiTi springs is the transient temperature changes experienced intra-orally because it has been shown that NiTi force properties are highly dependent upon temperature.…”

Section: Discussionmentioning

confidence: 99%

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In-vivo force decay of nickel-titanium closed-coil springs

Cox¹,

Nguyen²,

Koroluk³

et al. 2014

American Journal of Orthodontics and Dentofacial Orthopedics

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Introduction Nickel-titanium (NiTi) closed coil springs are purported to deliver constant forces over extended ranges of activation and working times. In vivo studies supporting this claim are limited. The objective of this study is to evaluate changes in force decay properties of NiTi closed coil springs after clinical use. Methods Pseudoelastic force-deflection curves for 30 NiTi coil springs (used intra-orally) and 15 matched laboratory control springs (simulated intra-oral conditions - artificial saliva, 37°C) were tested pre- and post-retrieval via Dynamic Mechanical Analysis (DMA) and the Instron machine, respectively, to evaluate amount of force loss and hysteresis change following 4, 8, or 12 weeks of working time (n=10 per group). Effect of the oral environment and clinical use on force properties were evaluated by comparing in vivo and in vitro data. Results The springs studied showed a statistically significant decrease in force (~12%) following 4 weeks of clinical use (p<0.01), with a further significant decrease (~7%) from 4–8 weeks (p=0.03) and force levels appearing to remain steady thereafter. Clinical space closure at an average rate of 0.91mm per month was still observed despite this decrease in force. In vivo and in vitro force loss data were not statistically different. Conclusions NiTi closed coil springs do not deliver constant forces when used intra-orally, but they still allow for space closure rates of ~1mm/month.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

In-vivo force decay of nickel-titanium closed-coil springs

Cox¹,

Nguyen²,

Koroluk³

et al. 2014

American Journal of Orthodontics and Dentofacial Orthopedics

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“…Springs of subgroup 3A began to rupture at 900%, and the ones in Group 2 began to rupture at 800% of activation. Comparison of these values is difficult because the literature mentions activations only up to 500%, 8 , 9 , 10 and only one study 11 tested springs until they ruptured. In this last study, however, activations were not correlated to the percentage of activation in relation to Y.…”

Section: Discussionmentioning

confidence: 99%

“…In those two clinical situations, deformations smaller than 7.4 mm and 5.7 mm, respective to each situation, would be considered clinically irrelevant. However, there are two other variables that should be considered when using nickel-titanium springs: one is the desired force, since the force plateau decreases with increased activation; 11 , 16 and the second is the relationship between the spring's clinical work range (Fig 3) and the SE plateau length, because even at a SIMT, the dimensions that are clinically used in Orthodontics could make the spring work outside its SE plateau (Fig 4), thus acting in a SE way only after some space is closed or even never acting in a SE way at all.…”

Section: Discussionmentioning

confidence: 99%

“…There are reports in the literature, without presenting any evidence, of activations of 500% the spring's original length without permanent deformation, 8 , 9 , 10 although imposing no limits to a higher activation. Only one paper 11 mentions ruptures in nickel-titanium springs excessively activated, but it does not correlate the rupture to the effective length of the nickel-titanium portion in the spring.…”

Section: Introductionmentioning

confidence: 99%

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

Vieira

Reis

Vaz

et al. 2017

Dental Press J. Orthod.

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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.

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Stainless steel and NiTi torque archwires and apical root resorption

et al. 2020

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Objective The amount of apical root resorption when using the torque-segmented archwire (TSA) was investigated as well as the extent and direction of the therapeutically indicated apical movement and the treatment duration. Materials and methods The degree of apical root resorption in 18 randomly chosen Class II and Class I patients treated with the TSA, as well as in 18 conventionally treated patients were evaluated using pre-and posttreatment panoramic radiographs. The sagittal and vertical apical movements and inclination changes were determined based on pre-and posttreatment lateral cephalograms. Nonparametric tests were applied to test between treatment groups and steps. The Mann-Whitney U test, Kruskal-Wallis, Pearson correlation and Wilcoxon signed-rank test were applied for statistical analysis (p < 0.05). Results The incidence of root resorptions was 89-94.4% in low or moderate level. The relative root-crown ratio (rRCR) was not statistically different between the TSA and control groups except tooth 12. The axis of the incisors in the TSA group was significantly improved. The main direction of movement of the apices of the central incisors was retrusion and extrusion. No interdependence between the amount of resorption and the parameters of treatment duration, extent and direction of apical movement were found. Conclusion The results of the study showed that the amount of apical root resorption with the TSA is slight to moderate and can be compared to conventional orthodontic treatment. The TSA is hence a suitable method for applying targeted torques to the incisors. Keywords Incisors • Orthodontic therapy • Tooth movement • Root-crown ratio • Orthodontic appliances Edelstahl-und NiTi-Torquesegmentbogen und apikale Wurzelresorption Zusammenfassung Ziel Der Umfang der apikalen Wurzelresorption ebenso wie das Ausmaß und die Richtung der therapeutisch angenommenen apikalen Bewegung sowie die Behandlungsdauer wurden bei Anwendung des Torquesegmentbogens (TSB) untersucht. Methoden Das Ausmaß der apikalen Wurzelresorption wurde an 18 willkürlich ausgewählten Klasse-II-und-I-Patienten, die mit dem TSB behandelt wurden, und an 18 konventionell behandelten Patienten anhand von prä-und posttherapeutisch erstellten Panoramaschichtaufnahmen beurteilt. Die sagittalen und vertikalen apikalen Bewegungen sowie die Änderungen der Inklination wurden anhand der FRS(Fernröntgenseitenbilder)-Aufnahmen bestimmt. Unterschiede zwischen Behandlungsgruppen und-schritten wurden mit nichtparametrischen Tests bestimmt. Mann-Whitney-U-, Kruskal-Wallis-, Pearson-Korrelation-und Wilcoxon-Rangsummen-Tests wurden zur statischen Analyse verwendet (p < 0.05).

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Mechanical behavior and clinical application of nickel-titanium closed-coil springs under different stress levels and mechanical loading cycles

Cited by 32 publications

References 9 publications

In-vivo force decay of nickel-titanium closed-coil springs

In-vivo force decay of nickel-titanium closed-coil springs

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

Stainless steel and NiTi torque archwires and apical root resorption

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