Superelastic Wires Research Articles

Effectiveness of low binding frictional materials: Evaluation of the binding frictional resistance of improved superelastic nickel-titanium alloy wires with different bracket combinations

Introduction: This study aimed to evaluate the binding frictional resistance of improved superelastic nickel- titanium alloy wires (ISW) with different bracket combinations and to verify the effectiveness of low binding frictional materials by applying them in orthodontic treatment. Materials and Methods: Straight stainless steel wire (SSW; 0.016 × 0.022-inch) and straight ISW (0.016 × 0.022- inch) were set to each displaced bracket, and the tensile resistance load was measured. The maximum tensile resistance load was statistically compared using the Tukey test. For exemplification, we treated a typical extraction case of Angle Class I crowding malocclusion with lip protrusion using lower binding frictional materials, which were selected based on tensile test results. Results: The SSW and metal bracket combination had the largest maximum tensile resistance load, and the ISW and metal slot-equipped plastic bracket combination had the smallest load (P < 0.01). In a patient treated using lower binding frictional materials, the active treatment period was 9 months. Satisfactory patient results were obtained without using reinforced anchorage. Conclusions: Binding frictional resistance varies, depending on the archwire and bracket combination. In a multibracket appliance, selecting materials with as low a binding frictional resistance as possible may make a more effective treatment.

Computational study on the effect of contact friction towards deactivation force of superelastic NiTi arch wire in a bracket system

This study investigated the impact of contact friction towards force-deflection behavior exhibited by superelastic NiTi arch wire during orthodontic treatment. A three-dimensional finite-element model of wire bending in bracket configurations was developed by employing UMAT/Nitinol and contact interaction. This model was used to predict the force response of NiTi wires upon bending at different friction conditions; friction coefficient at the wire-bracket interfaces was varied from 0.0 to 0.5. The force from the finite-element model was validated against experimental work, and good agreement was obtained between the two results. This investigation revealed that the superelastic wires exhibited the forces over a plateau trend in a frictionless bracket system. As the friction coefficient at the wire-bracket interface increased, the force plateau gradually transformed into a slope trend, suppressing the deactivation force to a lower magnitude. Over the increment of the friction coefficients, the rectangular wire registered the largest force reduction and slope variation at a ratio of −12.7 N/μ and −4.6 Nμ mm−1, respectively. Also, under the condition of high contact friction coefficient (μ ≥ 0.4), the deactivation force is suppressed to zero and inhibits tooth movement.

Seismic Behavior of Superelastic Shape Memory Alloy Spring in Base Isolation System of Multi-Story Steel Frame.

Owing to excellent re-centering capability and good damping behavior, superelastic shape memory alloys (SMAs) are emerging as a potential new material to enhance the seismic resilience of civil structures. This paper focuses on using base isolation with SMA device for isolated structures. SMA springs are deemed to be promising candidate as the damper in the base isolation system, due to the compact form, damping contribution, restoring capability and flexible stiffness. This paper reported the concept of an innovative spring which is made of superelastic SMA wire. Then cyclic loading tests were carried out to evaluate the interested cyclic properties. Parametric analyses based on finite element simulations were conducted to reveal the versatile performance of SMA springs. To further examine its seismic behavior in the base isolation system, the SMA spring was later installed at the isolation level of a multi-story steel frame, based on the finite element model built in the earthquake engineering simulation platform OpenSees. An ordinary elastic spring is included for comparison to highlight the features of SMA springs. Both isolated frames were subjected to real earthquakes. The comparisons indicated that using SMA spring is more effective in controlling maximum and residual deformation for the protected superstructures. Thus, this paper well demonstrated the feasibility and merits of using SMA springs in the isolated frames.

Hydrogen Effect on the Cyclic Behavior of a Superelastic NiTi Archwire

In this work, we are interested in examining the strain rate effect on the mechanical behavior of Ni–Ti superelastic wires after hydrogen charging and ageing for 24 h. Specimens underwent 50 cycles of loading-unloading, reaching an imposed deformation of 7.6%. During loading, strain rates from 10−4 s−1 to 10−2 s−1 were achieved. With a strain rate of 10−2 s−1, the specimens were charged by hydrogen for 6 h and aged for one day showed a superelastic behavior marked by an increase in the residual deformation as a function of the number of cycles. In contrast, after a few number of cycles with a strain rate of 10−4 s−1, the Ni-Ti alloy archwire specimens fractured in a brittle manner during the martensite transformation stage. The thermal desorption analysis showed that, for immersed specimens, the desorption peak of hydrogen appeared at 320 °C. However, after annealing the charged specimens by hydrogen at 400 °C for 1 h, an embrittlement took place at the last cycles for the lower strain rates of 10−4 s−1. The present study suggests that the embrittlement can be due to the development of an internal stress in the subsurface of the parent phase during hydrogen charging and due to the creation of cracks and local zones of plasticity after desorption.

Improved Super-elastic Ti–Ni Alloy Wire Treatment for Skeletal Class III Malocclusion with Anterior Crossbite Dentition

A 20-year-old man presented at our clinic with a primary complaint of irregular dentition and reverse bite. Clinical examination revealed skeletal Class III malocclusion with an anterior crossbite and a completely blocked #25 in the maxilla. Because he refused to receive orthognathic surgery and experienced only mild functional interference, a nonextraction treatment method was adopted. Space creation on the left upper arch was successfully performed using an open coil spring for molar distalization and the improved super-elastic Ti–Ni alloy wire (ISW) Multi-bends Edgewise Arch Wire (MEAW) technique. Furthermore, #25 was aligned completely. The Class III malocclusion was corrected using the ISW MEAW technique combined with Class III elastics on the lower arch. Treatment was completed in approximately 16 months and a satisfactory occlusion was achieved after active treatment.

Improved Super-elastic Ti–Ni Alloy Wire Treatment for Skeletal Class III Malocclusion with Anterior Crossbite Dentition

A 20-year-old man presented at our clinic with a primary complaint of irregular dentition and reverse bite. Clinical examination revealed skeletal Class III malocclusion with an anterior crossbite and a completely blocked #25 in the maxilla. Because he refused to receive orthognathic surgery and experienced only mild functional interference, a nonextraction treatment method was adopted. Space creation on the left upper arch was successfully performed using an open coil spring for molar distalization and the improved super-elastic Ti–Ni alloy wire (ISW) Multi-bends Edgewise Arch Wire (MEAW) technique. Furthermore, #25 was aligned completely. The Class III malocclusion was corrected using the ISW MEAW technique combined with Class III elastics on the lower arch. Treatment was completed in approximately 16 months and a satisfactory occlusion was achieved after active treatment.

Improved Super-elastic Ti–Ni Alloy Wire Treatment for Skeletal Class III Malocclusion with Anterior Crossbite Dentition

A 20-year-old man presented at our clinic with a primary complaint of irregular dentition and reverse bite. Clinical examination revealed skeletal Class III malocclusion with an anterior crossbite and a completely blocked #25 in the maxilla. Because he refused to receive orthognathic surgery and experienced only mild functional interference, a nonextraction treatment method was adopted. Space creation on the left upper arch was successfully performed using an open coil spring for molar distalization and the improved super-elastic Ti–Ni alloy wire (ISW) Multi-bends Edgewise Arch Wire (MEAW) technique. Furthermore, #25 was aligned completely. The Class III malocclusion was corrected using the ISW MEAW technique combined with Class III elastics on the lower arch. Treatment was completed in approximately 16 months and a satisfactory occlusion was achieved after active treatment.

Improved Super-elastic Ti–Ni Alloy Wire Treatment for Skeletal Class III Malocclusion with Anterior Crossbite Dentition

A 20-year-old man presented at our clinic with a primary complaint of irregular dentition and reverse bite. Clinical examination revealed skeletal Class III malocclusion with an anterior crossbite and a completely blocked #25 in the maxilla. Because he refused to receive orthognathic surgery and experienced only mild functional interference, a nonextraction treatment method was adopted. Space creation on the left upper arch was successfully performed using an open coil spring for molar distalization and the improved super-elastic Ti–Ni alloy wire (ISW) Multi-bends Edgewise Arch Wire (MEAW) technique. Furthermore, #25 was aligned completely. The Class III malocclusion was corrected using the ISW MEAW technique combined with Class III elastics on the lower arch. Treatment was completed in approximately 16 months and a satisfactory occlusion was achieved after active treatment.

Improved Super-elastic Ti–Ni Alloy Wire Treatment for Skeletal Class III Malocclusion with Anterior Crossbite Dentition

A 20-year-old man presented at our clinic with a primary complaint of irregular dentition and reverse bite. Clinical examination revealed skeletal Class III malocclusion with an anterior crossbite and a completely blocked #25 in the maxilla. Because he refused to receive orthognathic surgery and experienced only mild functional interference, a nonextraction treatment method was adopted. Space creation on the left upper arch was successfully performed using an open coil spring for molar distalization and the improved super-elastic Ti–Ni alloy wire (ISW) Multi-bends Edgewise Arch Wire (MEAW) technique. Furthermore, #25 was aligned completely. The Class III malocclusion was corrected using the ISW MEAW technique combined with Class III elastics on the lower arch. Treatment was completed in approximately 16 months and a satisfactory occlusion was achieved after active treatment.

Atypical Finishing with Lower Incisor Missing and Lower Primary Canine Retained using Improved Super-Elastic Ti-Ni Alloy Wire and Aligners

Introduction: This is an atypical finish case with extraction of bilateral deciduous canines and three incisor finishing due to lower lateral incisor congenital missing replaced by 1st premolars. We used improved super-elastic Ti-Ni alloy wire (ISW) for anterior anchorage preparation during the molar mesial drive. Aligners for finishing and detailing were adopted because patient was ordered to an international expatriate job. We are going to discuss the mechanism we used, atypical finishing consideration and timing for aligners using. Findings: This case report describes an adult female patient with lower incisor missing, lower bilateral primary canines retained, and dental crossbite. All were treated successfully with improved super-elasticity Ti-Ni alloy wire and aligners. Conclusions: After the treatment, a desirable outcome was achieved and the patient was pleased with the treatment result. To sum up, wire orthodontics (WO) and aligner orthodontics (AO) will be a flexible and humanity treatment strategy for patients in the future.

Effects of water environment and temperature on fatigue bending strength of Ni-Ti super elastic wire

Effects of water environment and temperature on fatigue bending strength of Ni-Ti super elastic wire

Evaluation of the corrosion resistance of welded Ni-Ti wires for orthodontic use

Abstract In recent decades, researches and analysis for applying the Ni-Ti alloys have become increasingly more specific, tending to studies on micro and nano actuators targeting applications in medical and orthodontic devices and in electromechanical microsystems. Thus, the welding processes have become important allies by promoting the union between shape memory alloy actuators (SMA) with similar and dissimilar ones, which is one way of increasing the useful applications of available materials, especially biomaterials. In this context, this study aimed atanalyzing the corrosion resistance in the weld region obtained by autogenous TIG micro welding in Ni-Ti superelastic wires with thermo-active Ni-Ti wires in a solution that simulates human saliva. The welded wires heat treatment made based on a factorial design 32. The results revealed that the TIG welding process used in this work generated welds of excellent quality, showing a good resistance to corrosion in the electrolyte that simulates human saliva. The experimental design used to investigate the influence of temperature and time of heat treatment in corrosion results generated a great experiment with temperature of 350 °C and time in the range of 20 minutes. This result was confirmed by means of electrochemical impedance spectroscopy tests.

Improvement of the dynamic instability of shallow hybrid composite cylindrical shells under impulse loads using shape memory alloy wires

In the present paper, the prevention of a probable instability after a sudden change in deformation of thin shallow cylindrical composite panels under impulse loads is pursued using embedded super-elastic SMA wires. A novel and practical framework is proposed to analyze these panels according to the precisely determined super-elastic function of the shape memory alloys. The suggested phase transformation algorithm can deal with the existing deficiencies in the modeling of the super-elastic behaviors. The governing equations of motion are obtained based on a matrix form of the energy equilibrium, using Sanders’ shell theory, and including the in-plane and rotary inertia effects. The resulting nonlinear finite element formulation is programmed in FORTRAN language to solve the time-dependent equations by the Newmark-beta numerical time-integration approach. The Budiansky-Roth criterion is used to determine the stability thresholds of the structures by detecting the abrupt and unexpected deformations under the suddenly imposed transverse concentrated load. Effects of imposing loads with different time durations, types, and characteristics, various amounts of the pre-tension, different viscous damping and volume fractions of the SMA are examined in order to determine the dynamic instability strength of the hybrid composite cylindrical shells and the resulting deformations in a fully non-linear solution. The large magnitudes of the pre-tension loads can change the instability performance of the structures under even small loads. In this study, the viscous damping of the host composite panels is ignored in comparison to the energy absorption due to the hysteresis loops of the stress-strain transformation diagrams of the SMA wires.

Anterior open bite due to temporomandibular joint osteoarthrosis with muscle dysfunction treated with temporary anchorage devices

Skeletal Class II high-angle open bite is often accompanied by osteoarthrosis of the temporomandibular joint (TMJ-OA). This type of malocclusion is challenging to correct, and it has been reported that patients with TMJ-OA treated with orthognathic surgery often experience skeletal relapse and a poor prognosis. This case report describes the treatment of a 25-year-old woman with retrognathia and TMJ-OA, whose masseter and temporal muscle activities were weak. Temporary anchorage devices were placed in the maxilla and the mandible, and the first molars were intruded. We used improved superelastic nickel-titanium alloy wires with tip-back bends for both arches, and intermaxillary elastics were used to upright the molars. After treatment, intrusion of the maxillary and mandibular first molars, counterclockwise rotation of the mandible, and improvement of occlusion and profile had been achieved. The patient's condyles were repositioned into ideal positions, and masticatory muscle activity was augmented and balanced. After 2years of retention, the mandibular and condylar positions were stable, and acceptable occlusion was maintained without recurrence of TMJ symptoms; harmonious activity of the masticatory muscles was retained. The findings of this case report suggest that molar intrusion using temporary anchorage devices for a patient with severe anterior open bite and TMJ-OA may be useful for improving stomatognathic function, occlusion, and facial esthetics.

Fretting damage of Ni-rich ultrafine grained NiTi superelastic wires

The effects of fretting on Ni-rich ultra-fine grained NiTi superelastic wires have been characterized. Fretting tests have been performed using wire on wire in 90° cross-cylinder configuration until 105 cycles in air at 25 °C. Constant displacement amplitude of 50 µm and normal loads of 10, 20 and 50 N were considered. For a normal load of 10 N, the tribosystem performed in Gross Slip Regime and the predominance of wear damage was observed. Mixed Fretting Regime was instead observed for normal loads of 20 N and 50 N. In these cases, the predominant damage mechanism was crack formation with the cracks oriented normal to the displacement direction. Occurrence of martensitic transformation in the contact region was inferred from the particular shape of the fretting loops. Due to their possible impact on biocompatibility, the debris detached from the tribosystem during the different experiments were collected and characterized by TEM. They consisted in agglomerations of nano-crystalline TiO2 (rutile) and NiO oxide particles sized between 10 and 20 nm.

The Low Velocity Impact Response of Shape Memory Alloy Hybrid Polymer Composites.

Polymer composites are sensitive to impact loading due to their low impact resistance. Shape memory alloy (SMA) wires have been used to improve the impact resistance of the polymer composite materials because of their unique superelasticity performance. In this study, a new SMA hybrid basalt fiber-reinforced polymer composite embedded with two perpendicular layers of superelastic SMA wires is designed and the low-velocity impact behavior is experimental investigated. For contrast, the conventional polymer composite without SMA wires is also tested as the reference laminate. The tests are carried out at three different impact energy levels (30, 60 and 90 J). Moreover, to find out indications for manufacturing of SMA hybrid composites with high impact resistance, four different SMA wires embedded modes are investigated. Visual inspection and scanning electron microscope methods are adopted to identify the damage modes of the impacted samples. Results show that the impact resistance of the hybrid laminates is improved due to the hybridization of SMA wires. The most effective impact resistance of the SMA hybrid composites can be obtained by incorporating the SMA wires with one layer between the front two plies and another layer between the bottom two plies into the composite structure.

Oriented ZnO nanoflakes on nickel-titanium alloy fibers for solid-phase microextraction of polychlorinated biphenyls and polycyclic aromatic hydrocarbons.

ZnO nanoflakes (ZnONFs) were electrochemically grown on a nickel-titanium alloy (NiTi) wire for use in solid-phase microextraction. Prior to the growth of ZnONFs, the NiTi wire was hydrothermally treated for in-situ growth of TiO2/NiO nanoflakes as a seeding base. The applied potential was used to control the dimensions of vertically oriented hexagonal ZnONFs. After annealing at 600°C, the resulting fiber display fairly selective affinity for polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons. The fibers were applied to the preconcentration of PCBs which then were quantified by HPLC with UV detection. Compared to commercial polydimethylsiloxane coatings, the new coating displays high extraction capability, rapid extraction kinetics and superior cycling stability. This is assumed to be due to its high surface-to-volume ratio, double-sided open access structure, and enhanced structural stability. The assay excels by (a) a wide analytical range (0.10 to 200μgL-1 of PCBs), (b) low limits of detection (20-17ngL-1), and (c) low standard deviations for the single fiber repeatability (<9.8%) and for the fiber-to-fiber reproducibility (<7.5%). Satisfactory accuracy and precision were achieved when PCBs were determined by this method in spiked rain water, river water and wastewater samples. Graphical abstract ZnO nanoflakes were fabricated on a superelastic nickel-titanium alloy wire in desired orientation with enhanced extraction capability and good extraction selectivity. The fabricated fiber was suitable for the determination of PCBs in environmental water samples.

SMA Constitutive Modeling Backed Up by 3D-XRD Experiments: Transformation Front in Stretched NiTi Wire

It has been known for a long time that martensitic phase transformation in NiTi shape memory alloys loaded in tension develops inhomogeneously via formation and propagation of macroscopic deformation bands resembling well-known Luders bands. Growing literature evidence supports the view that NiTi, in fact, develops a variety of localized deformation phenomena in particular geometries and loading modes. Coupling of cutting-edge experimental methods with dedicated modeling techniques can bring new insight into such a type of behavior. In this short review of our recent study, we demonstrate this synergic approach on the investigation of the martensite band in a stretched NiTi superelastic wire, in which the advanced technique of three-dimensional X-ray diffraction was complemented by NiTi-tailored constitutive model. We focus mainly on the modeling part, but the experimental background motivating and validating the chosen numerical approach is also briefly presented.

Photoelastic analysis of stress distributions in the root–bone interface when applying various orthodontic methods to subside lower anterior crowding

Dental crowding is a prevalent problem in modern society. Various factors, including different bracket systems and geometry of wire, influence the outcome using superelastic wire in the alignment stage of treatment. Currently, the use of light round wire instead of large-sized rectangular wire is emphasized to avoid powerful torsional stiffness. However, these guidelines lack scientific evidence for support. They have been written predominantly based on clinical experience. Therefore, the purpose of this study was to evaluate how factors such as bracket systems and wire geometry affect the stress distribution at the root-bone interface. Models using a photoelastic material (PL-3) to simulate bone tissue were fabricated. The simulated teeth were arranged as in lower anterior crowding. Then, the crowded teeth were subjected to orthodontic treatment with various types of bracket, ligating approaches using ligature wires of different sizes, shapes, and materials. Photoelastic images of the bone area of the models were obtained and compared. The results showed that wire size plays a more significant role than the material or cross-sectional shape of the wire in affecting the stress distribution at the simulated root-bone interface. The teeth ligated with a larger cross-sectional diameter of wire showed the application of excessive torque, which may cause root resorption and slow down tooth movement. These results not only demonstrate the scientific evidence backing clinical experience but also can be a useful reference for further clinical application.

Initial arch wires used in orthodontic treatment with fixed appliances.

Initial arch wires used in orthodontic treatment with fixed appliances.