NiTi Research Articles

Evaluation of the Difference in the Rate of Canine Retraction Assisted by Piezocision and Discission in Human Subjects: A Preliminary Parallel-Arm Prospective Clinical Study.

The objective of the study was to evaluate the rate of orthodontic tooth movement assisted by piezocision and discission in extraction cases. Twelve adults (20-35 years) requiring upper premolar extraction for orthodontic treatment were included in this preliminary parallel-arm clinical study. Participants (randomly allocated) in Groups A and B received piezocision and discision-assisted corticotomy cuts at the premolar extraction site, respectively, contralateral side served as the control. Canine retraction was started bilaterally using closed coil NiTi (Nickel titanium) springs. A schedule of fortnightly activation was followed for 3 months. Stage models were made monthly (M0, M1, M2, M3). Models were scanned using a 3-shape intraoral scanner, and the displacement of the canine was measured bilaterally in the stage models. A self-designed questionnaire was used to assess patients pain and satisfaction levels on a visual analogue scale. The rate of canine retraction at the piezocision site was twice that at the control site in group A (p=0.007). The rate of canine retraction at the dissection site was twice that at the control site in group B (p=0.012). However, there was no significant difference in the rate of retraction between the two surgical techniques. Pain and disturbance were noticed in the discission group at 50 and 67% respectively. Discision is comparable to piezocision for accelerating orthodontic tooth movement. Although dissection can speed orthodontic treatment, it should be used with caution as it could pose technical and clinical difficulties, particularly in the posterior buccal region of the oral cavity.

Comparison of Dentinal Defects Formation in Straight, Moderate and Severely Curved Canals by Three Distinctive Nickel Titanium Instruments: An in vitro Study.

It is stated that engine-driven instruments might cause dentinal defects during root canal preparation. These defects might spread and progress into greater fractures or vertical root fracture. This study aimed to compare the incidence of dentinal defects that might arise all through preparation of root canals, using One Shape, RaCe, and WaveOne systems in canals with a curvature (0-20°) and (20-40°). In this in vitro study, 150 mandibular first molars were enrolled. Based on the degree of curvature in the mesial roots, the samples were divided into two groups (n=75) of straight and moderately curved canals (0-20º), and severely curved canals (20-40°). Then each group was randomly divided into four sub-groups. In subgroups 1 to 3 from each group, canals were prepared using WaveOne, One Shape, and RaCe. Then all roots were sectioned at 3, 6 and 9-mm distances from the apex. The slices were evaluated using stereomicroscope at 12× magnification. The data were analyzed using the Chi-square and Fisher's exact tests and the level of significance was set at 0.05. Fracture and other defects were not found in the control groups. In canals with curvature (0-20°), WaveOne caused the maximum dentinal defects and RaCe produced the least. Moreover, in canals with curvature (20-40°), One Shape caused the maximum dentinal defects while WaveOne and RaCe caused equal dentinal defects approximately. There was a statistically significant relationship between the performance of RaCe and One Shape in canals with curvature (0-20º) and (20-40º), (pValue< 0.05) while no statistically significant difference was observed in connection to the performance of WaveOne (p> 0.05).

Radiation shielding properties of aluminium alloys

X-ray/gamma, neutron, electromagnetic and Bremsstrahlung shielding parameters were studied for the different aluminium alloys such as Al–Li, Duralumin, Hiduminium, Hydronalium, Italma, Magnalium, Ni–Ti–Al and Y-alloy. X-ray/gamma shielding properties such as mass attenuation coefficient, Half Value layer (HVL), Tenth Value layer (TVL), effective atomic number (), electron density (), build-up factors (BF), KERMA coefficient (KE), and radiation protection efficiency (RPE) of Al alloys of various compositions were studied. Shielding effectiveness for electromagnetic radiation at different frequency ranges from radio waves to infrared radiations is studied in the above-mentioned aluminium alloys. Further, we investigated neutron scattering lengths and cross sections for the above alloys. Bremsstrahlung shielding parameters such as Bremsstrahlung dose rate, probability of bremsstrahlung and bremstrahlung production efficiency were also studied. Bremsstrahlung's dose rate for the distinct β emitters corresponding to maximum energy are investigated for the different aluminium alloys. Thorough investigations reveal that Ni–Ti–Al aluminium alloy is found to be a good absorber of X-ray/γ radiation, neutron, electromagnetic and Bremsstrahlung radiations. As a consequence, we recommend Ni–Ti–Al as a good radiation shielding material among the aluminium alloys.

Combinatorial Alloy Design and Microstructure Evolution in Laser-cladded Al–Co–Cr–Fe–Ni–Ti Compositionally Complex Alloys

In this work, we propose a strategy for high-throughput design and development of compositionally complex alloys combining theoretical and experimental alloy screening. This methodology was applied for the exploration of the (Co2CrFeNi2)1-x-yTixAly subsystem of so-called high entropy superalloys in the Al–Co–Cr–Fe–Ni–Ti alloy system. Alloy design was guided by thermodynamic calculations based on the CALPHAD approach. The evolution of the microstructure with increasing Al and Ti content was analyzed in the as-built, homogenized and age-hardened conditions by means of scanning electron microscopy, energy-dispersive X-ray spectroscopy and electron backscattered diffraction. Additionally, the evolution of the sample hardness with increasing Al and Ti contents was determined for all conditions. Based on the experimental results, the reliability of the CALPHAD calculations was assessed. Generally, a good agreement between calculations and experiments is achieved in the homogenized state. In the aged conditions, the CALPHAD predictions of the precipitation processes are partly inaccurate and need improvement. Optimal Al and Ti concentrations are derived for age hardening through L12 and combined L12 + B2 precipitations.

Catalysis Under Alternating Magnetic Field: Rethinking the Origin of Enhanced Hydrogen Evolution Activities

AbstractMagnetic fields are proposed to be a clean and powerful tool to boost the heterogeneous reaction processes, from the simple two‐electron transfer hydrogen evolution to the complicated proton‐coupling of multi‐electron transfer reactions. Although many mechanisms are proposed to explain the field‐assistant enhancement of activities, it remains an open question of how to understand the contradictory experiment results. In this study, the interplay between the alternating magnetic field (AMF) and the working electrodes from the viewpoint of their relative geometric positions is investigated. It is found that the HER current is almost doubled at an AMF of 25 mT when Pt foil and AMF are parallelly arranged, which is more significant than the perpendicularly arranged configuration. A significant increase in solution resistance is observed, which is in contradiction to previous works. The changing of currents with the AMF strength is investigated for the diamagnetic Cu, ferromagnetic Ni, and paramagnetic Ti and Pt wire, all suggesting the vital role of the induced electromotive force, which is a result of the relative geometric positions between the electrode and AMF. The findings provide an alternative mechanism for the magnetic field‐assisted electrocatalytic processes, which is helpful for the rational design of high‐performance catalysts.

Anti Corrosion Activity of CRF (Cardiac Risk Free) Drug for SS316L, Ni–Ti, and Ti-6Al-4V in Artificial Blood Plasma

Anti Corrosion Activity of CRF (Cardiac Risk Free) Drug for SS316L, Ni–Ti, and Ti-6Al-4V in Artificial Blood Plasma

Structural, mechanical, and thermodynamic properties of Ni–Ti intermetallic compounds: First-principle calculation

Intermetallic compounds were applied widely in the fields of automotive and aerospace because of its excellent shape memory effect. In this work, the structural, mechanical, and thermodynamic properties of Ni–Ti intermetallic compounds are studied by first-principle calculation. The results show that Ti, NiTi3, NiTi2, NiTi, Ni4Ti3, Ni3Ti, Ni4Ti, and Ni are stable based on Born stable criterion. On the mechanical aspect, the bulk modulus of Ni–Ti intermetallic compounds increases with the rising electron density. Their ductility is ranked as follows: NiTi3 &amp;gt; Ni4Ti3 &amp;gt; NiTi2 &amp;gt; Ni4Ti &amp;gt; NiTi &amp;gt; Ni3Ti. And when the ratio of Ni and Ti is 3:1, it is the hardest. In addition, the Ni–Ti intermetallic compounds in this work are anisotropy, except NiTi2. On the thermodynamic aspect, the Debye temperature θD, melting point Tm, and minimum thermal conductivity kmin of Ni–Ti intermetallic compounds increase first and then decrease with the rising content of Ni. The θD and kmin of NiTi3 are the minimum among the Ni–Ti ICs mentioned above, and θD of Ni3Ti and kmin of NiTi are both the maximum. The melting point of Ni3Ti is 1940 K, it is the highest temperature.

On the hydrogen storage properties of cast TiFe mechanically milled with an intermetallic LaNi5 and rare-earth elements La and Ce

This study provides detailed insight into the effects of adding an intermetallic LaNi5 and rare earth elements La and Ce on the hydrogen storage properties of cast TiFe alloy. To preserve the composite nature of the materials, the addition was done by short-duration ball milling. Morphological investigation revealed the presence of two distinct regions, viz., the primary matrix TiFe region and a secondary region mainly containing the additives. The relative abundance of La and Ni were close to 1/5 in both the regions indicating that LaNi5 did not decompose, and no La–Ni–Ti–Fe phase formed. In the La-added TiFe, diffraction peaks correspond to a high-temperature La phase, and in the Ce-added TiFe, peaks indicative of CeO2 rather than elemental Ce were observed. The milling process only induced microstrains in the LaNi5-added TiFe. Notably, hydrogenation was more complete and faster when the additive was Ce and completely reversible when the additive was LaNi5. However, the kinetics of the La-added TiFe were slow, and stable LaH3 was observed.

Immediate Weightbearing Following First Metatarsal Phalangeal Joint Arthrodesis With 2 Nickel Titanium Alloy Staples

The use of staples has been shown to be a reasonable fixation technique to achieve stability of a first MTPJ arthrodesis. Although it has been shown to be a weaker construct than crossed screws or plate and screw combinations, their ease of insertion, low profile, and stability make them a desirable choice for first MTPJ arthrodesis fixation. However, because of this relative weakness, the question remains whether immediate weightbearing when using staples is advisable. The aim of this study is to determine whether the use of 2 nickel-titanium alloy (NITINOL) staples, placed at 90 degrees to one another is a stable enough construct to support full, immediate weightbearing following first MTPJ arthrodesis. We performed a retrospective chart review of patients undergoing first MTPJ arthrodesis by a single surgeon utilizing 2 NITINOL staples placed at 90 degrees to one another. Patients were allowed to be fully weightbearing immediately postoperatively. Forty-seven of 50 (94%) patients achieved complete radiologic consolidation of fusion at 12 weeks, with only 3 requiring revision surgery for nonunion. All of the patients requiring revision surgery for nonunion, had preoperative diagnosis of hallux abducto valgus. We concluded that the use of 2 NITINOL staples placed at 90 degrees to one another is a viable option for first MTPJ arthrodesis, and immediate weightbearing does not increase rate of nonunion or incidence of revision surgery when compared to other fixation techniques.

Implementing rotary root canal instrumentation in the clinical training of undergraduate students from Saudi Dental Schools: A cross-sectional survey

Introduction: Rotary nickel–titanium files for root canal therapy have become standard treatment modalities in general practice and specialized dental centers. Undergraduate dental students should receive proper training in using rotary files before graduation. Therefore, this study aimed to provide detailed insight into the implementation of rotary root canal instruments in the clinical training of undergraduate students in Saudi Arabia. Materials and Methods: Two randomly selected private schools and 13 government-owned schools were selected to represent all administrative regions in Saudi Arabia. The SurveyMonkey® questionnaire was sent to each dental school through direct communication. It covered most aspects of the rotary root canal instruments used in the clinical training of undergraduate students before graduation. Results: Approximately 92.9% of the included dental schools reported using rotary files in undergraduate teaching; however, only 57.1% had specific clinical requirements for rotary root canal instrumentation in their curricula. Laboratory simulation sessions were the most commonly used preclinical training methods for rotary instrumentation (85.7%). Most dental schools implemented rotary file training in the 4th and 5th years (53.8% and 38.5%, respectively). The ProTaper® (Universal, Next, Gold) was the most commonly used rotary system. Most dental schools had an instructor-to-student ratio of 1:5. Conclusion: Most Saudi dental schools have adopted rotary files during their undergraduate training. However, the curricula of some dental schools do not include a predetermined number of clinical cases treated with rotary instrumentation to ensure better training for students before graduation.

Investigation and optimization in electrochemical arc drilling of Ni55.7Ti nickel–titanium shape memory alloy with molybdenum electrode

Investigation and optimization in electrochemical arc drilling of Ni55.7Ti nickel–titanium shape memory alloy with molybdenum electrode

Corrosion resistance and cytocompatibility of Ti–19Zr–11Nb–4Ta shape memory alloy for biomedical applications

The corrosion resistance and cytocompatibility of Ti–19Zr–11Nb–4Ta shape memory alloy have been investigated. Well superelasticity of 4.6% was detected in the Ti–19Zr–11Nb–4Ta alloy with a triphasic microstructure of β, α′′ and ω phases. The alloy performs a higher corrosion resistance than Ti and Ti–6Al–4V indicated by the electrochemical experiments in Hank's and 0.9% NaCl solutions. Low release rate of ions in Ti–19Zr–11Nb–4Ta alloy was also demonstrated by the 21 days immersion tests with the reference of biomedical Ti, Ti–6Al–4V and Ni–Ti alloys. Meanwhile, the Ti–19Zr–11Nb–4Ta alloy performs a well cytocompatibility by MC3T3-E1 cells' adhesion and proliferation tests, which is expected to be utilized as a new biomedical shape memory alloy.

Self-centric cyclic resistance of reinforced concrete shear wall with Shape Memory Alloy: Numerical and experimental large-scale model

Over several decades, numerous researches have been routed to forge ahead in enhancing the building performance against dynamic loads. Nowadays, smart materials such as Shape Memory Alloy (SMA) have found profound impact in many applications of civil engineering. Nickel titanium alloy (NiTi) is one of the most famous among types of SMA. The current paper studies the behavior of shear wall, representing one of the most efficient lateral bracing element, structured by NiTi subjected to cyclic loading. Due to the unique characteristics of NiTi particularly in capacity to restore its original shape after unloading, the improvement in shear wall displacement recovery, wall ductility, hysteric behavior and inter-story drift ratio is presented. For this purpose, experiment study on large scale shear walls with aspect ratio 1.9 is conducted to investigate the effect of the intensity of NiTi on cyclic response. Two ordinary walls, as reference structures, and two hybrid walls are set up in order to perform the study. In addition, the validation of numerical simulation is examined by comparing its results with that obtained by the experiments and a pretty much in agreement is found. Hence, three-dimensional modeling by mean of ANSYS19 is extended to study the effect of NiTi length throughout the wall height on the shear wall response. The results showed that the existing of NiTi controls the cracks propagation and confines the majority in the lower third of the wall. Furthermore, for NiTi-wall, the study showed remarkable enhancement in recover capacity by 77 % and significantly increase in drift capacity ratio by 16.5 % relies on the NiTi ratio. Besides, some significant observations like the profile of wall curvature and energy dissipation are analyzed in this paper.

Effect of chitosan–tungsten composite coating obtained by electrophoretic deposition on the corrosion resistance of Ni–Ti alloy in physiological medium

Ni–Ti shape memory alloys (Nitinol) are suitable for biomedical applications such as orthodontic, orthopedic, and cardiovascular implants. However, to avoid local inflammatory processes, efforts are being made to functionalize the surface of the Ni–Ti alloy with bioactive materials. Chitosan-based composite coatings can be applied to improve the properties of Ni–Ti alloys due to their excellent properties, such as low toxicity, biocompatibility, biodegradability, and good film-forming ability. In this work, the chitosan–tungsten composite (Chit–W) was evaluated as a protective coating for Ni–Ti alloy in a physiological medium (Ringer's solution). The results of surface morphology and chemical composition (SEM and EDX) confirmed the formation of the composite coating formed by a chitosan matrix impregnated with tungsten oxide nanoparticles. Corrosion resistance results proved the efficiency of the composite coating, acting as a protective barrier between the surface of the substrate (Ni–Ti) and the corrosive environment. Therefore, the results point to a possible system candidate (Ni–Ti alloy coated with Chit–W composite) suitable for applications in orthopedic implants.

Parametric optimization of electric discharge machining of Ni 55.65Ti based shape memory alloy using NSGA II with TOPSIS

Nickel–Titanium based shape memory alloys (SMAs) are a unique category of smart materials that possess remarkable properties like super-elasticity, shape memory effect, high wear and corrosion resistance, thereby rendering them appropriate for uses such as composite structures, aerospace, and biomedical uses etc. These distinctive features make these alloys ‘difficult in machining’ using the traditional approach of machining process. In the present investigation, machinability aspects of Ni55.65Ti-SMAs using non-traditional electric discharge machining process has been studied. The effect of input process parameters i.e., pulse time ON, duty factor, peak current on the surface roughness and material removal rate has been investigated. The output responses viz. Minimum surface roughness along with maximum material removal rate having values of 6.828 μm and 4.552 mm3/sec respectively were achieved. Furthermore, empirical modelling and ANOVA study have been executed based on the full factorial design analysis. The non-dominated sorting genetic algorithm IIalgorithm IIalg2 commonly known as NSGA II, used crowding distance approach for multi-objective process optimization. The results obtained with NSGA-II were again ranked using Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) approach to give a more thorough understanding of the solution space and opt for the best possible solution.

Finite Element Analysis of the Mechanical Behaviors of Endodontic Nickel–Titanium Rotary Files: A Review

Finite Element Analysis of the Mechanical Behaviors of Endodontic Nickel–Titanium Rotary Files: A Review

In vitro evaluation of cytotoxicity and genotoxicity of porous nickel titanium dental implants produced by metal injection molding technique.

Porous NiTi (pNiTi) is a promising biomaterial for functional long-term implantation that has been produced using various manufacturing techniques and tested for biocompatibility. pNiTi produced using a more recent technology of Metal Injection Molding (MIM) has shown better physical and mechanical properties than those produced by earlier manufacturing methods, but its biocompatibility has yet to be determined. Hence, extracts from pNiTi dental implants produced by MIM were tested for cytotoxicity and genotoxicity in this work. Its toxicity was evaluated at the cellular and in vitro levels using elution and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assays. Short-term testing revealed that pNiTi extract was cytocompatible with L-929 fibroblast and V79-4 lung cells, with no cell lysis or reactivity observed, respectively (USP grade 0). Following exposure to varied extract concentrations, good cell viability was observed where the lowest concentration showed the highest optical density (OD) and cell viability (2.968 ± 0.117 and 94%, respectively), and the highest concentration had the least OD and cell viability (2.251 ± 0.054 and 71%, respectively). pNiTi extracts demonstrated genocompatibility in two independent assays: mutagenic potential using a bacterial reverse mutation test and a clastogenic effect on chromosomes using the micronucleus test. Similar to the negative control reactions, there was no significant increase in revertant colonies following exposure to 100% pNiTi extract with and without metabolic activation (p = .00). No DNA clastogenic activity was caused by pNiTi at varied extract concentrations as compared to the negative control when tested with and without metabolic activation (p = .00). As a result, both cytotoxic and genotoxic investigations have confirmed that pNiTi dental implants utilizing the MIM process are cytocompatible and genocompatible in the short term, according to the International Standard, ISO 10993 - Parts 3, 5, and 33.

0.8 mm Ni–Ti shape memory alloy wires: Post-training behavior and application in a cold-formed steel structure

This study explores the post-training performance, mechanical training strategy, and potential seismic application of shape memory alloy (SMA) wires. A part of SMA wire specimens were trained by different training protocols, and subsequently all the untrained and trained SMA wire specimens were tested at room temperature under various cyclic loading protocols. It is observed that the incremental cyclic training could lead to a higher post-yield stiffness during the post-training stage at a certain expense of residual strain and forward transformation stress, and the post-training hysteretic behavior will be stable and predictable within the historical training strain amplitude. The influence of training on mechanical performance of SMA wires under near-fault loading was revealed and evaluated. Following the test program, a cold-formed steel (CFS) joint model employing SMA wires is proposed and analyzed to demonstrate the feasibility and efficiency of trained SMA wires for optimizing seismic performance. The finite element (FE) analysis results indicates that the self-centering CFS joint can effectively optimize the original pinched hysteretic response, including mitigating residual displacement, and improving the peak strength, initial stiffness and energy-dissipate capacity.

The scientific evidence for pre-adjusted edgewise attachments and mechanics.

Introduction Fixed orthodontic appliance systems continue to evolve with a wealth of evidence emerging to underpin these refinements.Aims To present the evidence from comparative prospective research informing the selection of fixed appliance design and mechanics.Design Detailed literature review.Materials and methods An electronic search to identify randomised controlled trials and clinical controlled trials was undertaken using pre-defined search terms.Results Based on high-level evidence, no one bracket system has been proven superior in terms of efficiency or outcome. Similarly, a clear advantage associated with one wire type or dimension has not been shown. The effect of lacebacks in terms of anchorage management appears to be limited, while elastomeric chain and nickel titanium closing coils are associated with similar rates of space closure.Discussion A wealth of high-quality recent evidence to support the selection of fixed appliance attachments, archwires and auxiliaries, including lacebacks and space closing mechanics, was identified.Conclusions There has been a considerable increase in the amount of high-quality evidence informing the choice of pre-adjusted edgewise mechanics in recent years. This information can be used to make evidence-based decisions in the selection and manipulation of fixed appliances during daily practice.

Comparison of the skeletal, dentoalveolar, and periodontal changes after Ni–Ti leaf spring expander and rapid maxillary expansion: a three-dimensional CBCT based evaluation

BackgroundThe aim of the present study was twofold:(1) three-dimensionally evaluate the quantitative skeletal and dentoalveolar changes after Ni–Ti leaf spring expander (leaf expander) and rapid maxillary expansion (RME) in mixed dentition patients;(2) analyze the modifications of the buccal alveolar bone plate of the maxillary first permanent molars.MethodsPatients who underwent CBCT scans before and after maxillary expansion were randomly selected from the records archived at the Department of Biomedical Surgical and Dental Sciences, University of Milan, Italy.Inclusion criteria were the following: no systemic disease or syndromes; maxillary transverse deficiencies (difference between the upper intermolar width and the lower intermolar width of at least 3 mm and/or clinical need based on radiographic evaluation), early mixed dentition with ages between 7 to 10 years old; cervical vertebra maturation stage (CVMS) 1 or 2; no pathologic periodontal status; skeletal class I or II; maxillary expander cemented on the upper second deciduous molars. Exclusion criteria were the following: patients with pubertal or post-pubertal stage of development (CVMS 3–6); late deciduous or late mixed dentition, impossibility to use the second primary molar as anchorage; skeletal class III malocclusion; craniofacial syndromes; patients unable to be followed during the treatment period. Twenty-three patients treated with Leaf Expander, 11 males (mean age 7.8 ± 0.6 years) and 12 females (mean age 8.1 ± 0.8 years), met the inclusion criteria and constituted the case group. Twenty-four (control group) treated with conventional RME, 12 males (mean age 8.4 ± 0.9 years) and 12 females (mean age 8.1 ± 0.7 years). The paired-sample T test was used for intra-group comparison to evaluate the difference between before (T1) and after (T2) maxillary expansion. Independent sample t-test was computed to perform between groups comparison of the skeletal, dentoalveolar, and periodontal changes.ResultsThe Leaf Expander and RME group showed a significant increase between T1 and T2 for most of the skeletal and dentoalveolar variables. Concerning the skeletal variables only the RME demonstrated a significant increase at the level of the posterior nasal (PNW) and apical base width (PABW) and maxillary mid-alveolar width (MMW). Despite this, when compare with the Leaf Expander, the RME group exhibited a statistically larger width increase for only two skeletal parameters: PNW (p = 0.03) and MMW (p = 0.02). No significant changes at the periodontal level were found in either group.ConclusionsAccording to the current research, the authors confirm the effectiveness of the Leaf Expander and RME to produce similar skeletal and dentoalveolar effects in mixed dentition subjects. Moreover, the devices anchored to deciduous teeth did not reduce the thickness and height of the buccal bone at the level of the maxillary permanent first molars in either of the two groups.