Comparison of alignment efficiency of different sizes of superelastic nickel-titanium archwires in the initial phase of fixed orthodontic treatment: A single-center, double-blind randomized clinical trial

INTRODUCTION

This 3-arm parallel, double-blind study aimed to evaluate the alignment efficiency of 3 different diameters of superelastic nickel-titanium (NiTi) archwires during the initial phase of orthodontic treatment.

METHODS

Ninety-three patients with nonextraction treatment in the mandibular arch (using 0.022-in Roth prescription brackets) were randomly allocated into 3 groups: 0.012-in NiTi (group 1), 0.014-in NiTi (group 2), and 0.016-in NiTi (group 3). The alignment change was measured using the modified Little's irregularity index before archwire placement and every 4 weeks. The alignment efficiency of the 3 groups was analyzed.

RESULTS

Ninety patients were analyzed (group 1: n = 29, group 2: n = 31, and group 3: n = 30; overall mean age, 16.6 years). The overall Wald test analysis revealed that wire type was not statistically significant (P = 0.91), whereas time exhibited significance as expected (P <0.001). Furthermore, the interaction between wire type and time was not significant (P = 0.93). The time-adjusted estimated difference between 0.014-in and 0.012-in was -0.49 (95% confidence interval, -2.83 to 1.85; P = 0.68). The time-adjusted estimated difference between 0.016-in and 0.012-in was -0.45 (95% confidence interval, -2.95 to 2.05; P = 0.72). No harm was observed.

CONCLUSIONS

The clinical performance of 3 different sizes of NiTi archwires was similar. In addition, 0.014-in and 0.016-in NiTi archwires demonstrated better performances in aligning any irregularities because of a greater number of wire deformations in the 0.012-in group.

REGISTRATION

IR.TBZMED.REC.1395.1039.

PROTOCOL

The protocol was not published before trial commencement.

FUNDING

None.

The Effect of Three Metal Oxide Nanocoatings on the Frictional Resistance of Superelastic Orthodontic Archwires: A Comprehensive In vitro Analysis

AIM AND OBJECTIVE

To evaluate and compare the impact of nanocoatings made of oxides of Aluminum, Titanium, and Zirconium, on the frictional resistance on three types of superelastic orthodontics archwires namely; nickel titanium, copper nickel titanium and low hysteresis nickel titanium.

MATERIALS AND METHODS

There are120 archwire segments of equal dimensions were divided into four groups (n = 30) with 10 samples each of low hysteresis superelastic archwires; NiTi archwires and CuNiTi archwires. While group A were uncoated, other groups were nanocoated with group B: Aluminum oxide; group C: Titanium dioxide; group D: Zirconium oxide respectively. Upper premolar metal brackets MBT 0.022 slot were used for testing. The frictional properties of the archwires were measured using a Universal testing machine equipped with a custom-made jig. Statistical tests including analysis of variance and post hoctests were used for analysis.

RESULTS

The least frictional resistance among the three types of archwires was seen with low hysteresis(L&H) NiTi wires coated with ZrO2 (3.1253 ± 0.45822 N) and the highest with uncoated CuNiTi archwires (7.1113 ± 1.29031 N). Among the nanocoatings, the least value was found for ZrO2 nanocoatings followed by TiO2, Al2O3 and highest with uncoated archwires across all three types of archwires.

CONCLUSION

Low hysteresisNiTi have the least frictional resistance compared to CuNiTi and NiTi archwires. The findings also suggest that all the three metal oxide nanocoatings reduce frictional resistance significantly, among which, ZrO2 nanocoatings were the most effective. This study underscores the potential efficacy of metal oxide nanocoatings in reducing archwire friction and, consequently, will improve orthodontic treatment efficiency and patient comfort. How to cite this article: Dilip S, Rajkumar K. The Effect of Three Metal Oxide Nanocoatings on the Frictional Resistance of Superelastic Orthodontic Archwires: A Comprehensive In vitro Analysis. J Contemp Dent Pract 2024;25(7):649-655.

Multi-Force Bio-Active™ Archwires and Various Contemporary NiTi Multi-Force Archwires: Properties and Characteristics-A Review

The manufacturing of orthodontic archwires made from NiTi alloy has undergone numerous changes from the second half of the last century to modern times. Initially, superelastic-active austenitic NiTi alloys were predominant, followed by thermodynamic-active martensitic NiTi alloys, and, finally, the most recent development was graded thermodynamic alloys. These advancements have been the subject of extensive investigation in numerous studies, as they necessitated a deeper understanding of their properties. Furthermore, it is imperative that we validate the information provided by manufacturers regarding these archwires through independent studies. This review evaluates existing studies on the subject with a specific focus on the Bio-active multi-force NiTi archwire, by examining its mechanical, thermal, and physicochemical properties before and after clinical use. This archwire consists primarily of Ni and Ti, with traces of Fe and Cr, which release graduated, biologically tolerable forces which increase in a front-to-back direction and are affected by the temperature of the environment they are in. The review provides information to practicing orthodontists, facilitating informed decisions regarding the selection and use of Bio-active™ archwires for individual patient treatments.

Qualitative and Quantitative Evaluation of Different Types of Orthodontic Brackets and Archwires by Optical Microscopy and X-ray Fluorescence Spectroscopy

The wear behaviour and chemical composition of orthodontic components influence the mechanical characteristics of a fixed orthodontic treatment. The purpose of this paper is to evaluate the surface alterations of different types of brackets (aesthetic, metallic, and conventional self-ligating) and archwires (superelastic and thermal) subjected to wear tests through optical microscopy and, subsequently, to identify the chemical elements of accessories by X-ray fluorescence. The cycles (5000 for each bracket and 10,000 for each wire) of the tribological test were carried out in dry conditions inside a machine that allows alternating sliding. The results of the study highlighted different wear behaviours even within the same type of brackets and archwires. The monocrystalline sapphire brackets maintain their aesthetic properties despite traces of wear inside the slots and contain minimal amounts of nickel. Superelastic NiTi archwires have a better overall rating than thermal wires, as they do not show significant surface wear alterations.

Comparison of two different initial archwires for tooth alignment during fixed orthodontic treatment-A randomized clinical trial

OBJECTIVES:

The aim of the study was to clinically evaluate and compare 0.016-inch superelastic nickel–titanium (NiTi) and 0.016-inch heat-activated nickel–titanium (NiTi) archwires in terms of alignment efficiency, root resorption, and pain intensity.

METHOD:

A total of 20 patients requiring fixed orthodontic treatment, having Little's irregularity index of 5–8, and requiring first premolar extractions were recruited. They were randomly allocated to receive two different archwires (0.016-inch superelastic NiTi or 0.016-inch thermoelastic NiTi). Good-quality impressions were taken of the lower arch before archwire placement (T0) and at every month after that till the alignment was complete. The rate of tooth alignment was measured on casts by determining Little's irregularity index. The pain experienced by the patient was assessed 24 hours and 1 week after the placement of the archwire on a visual analogue scale. Cone beam computed tomographic radiographs of lower anterior teeth were taken before and after alignment to assess root resorption. Data obtained were subjected to statistical analysis using the SPSS software (version 20.0). The level of significance was kept at 5%.

RESULTS:

The repeated measures ANOVA indicated that there was no significant difference in the aligning efficiency of superelastic and heat-activated NiTi wires. (p = 0.45). The Mann Whitney U test showed that superelastic NiTi wires had statistically significant higher VAS scores than heat-activated NiTi at 24 hours and 1-week interval (p < 0.05). Student's t-test indicated greater root resorption with superelastic NiTi but the difference was not statistically significant.

CONCLUSION:

Both the wires showed similar aligning efficiency and resulting root resorption. Superelastic NiTi was observed to produce more pain compared to heat-activated NiTi in the aligning phase.

Changes in the mechanical properties of two nickel-titanium archwires after 3 months of clinical usage

BACKGROUND

Nickel-titanium archwires have unique mechanical properties that make them the archwire of choice during the first phase of orthodontic treatment. However, during its clinical use when subjected to oral conditions, these properties can undergo great changes.

MATERIALS AND METHODS

A sample of 24 randomly chosen superelastic NiTi orthodontic archwires (12 TE and 12 PSE) with a 0.014-inch round section from the same manufacturer were distributed into four groups of six archwires each. The first two groups were new wires (as-received), which were used as controls (T0), and the other two were collected after 3 months of clinical usage (as-retrieved) in orthodontic patients (T1). Mechanical properties were measured by mechanical tensile testing and three-point bending tests under the same experimental and temperature conditions (36°C) in a universal testing machine. Comparisons between the groups at T0 and T1 were performed with t-tests and Mann-Whitney U tests. A paired t-test and Wilcoxon signed rank sum test were used for intragroup comparisons (T1-T0).

RESULTS

At baseline, PSE wires presented significantly (P < 0.05) higher load at fracture, range, ultimate tensile strength (UTS), yield strength, springback, maximum tension and flexural ultimate strength (FUS) than those of TE wires. At T1, a significant decrease in load at fracture and UTS in PSE wires and in FUS in TE wires was found. After 3 months of clinical usage, the changes (T1-T0) in the mechanical properties of both alloys were similar.

CONCLUSIONS

After 3 months of clinical usage, wires lost some of their mechanical properties and had less resistance to breakage. However, the as-received differences between both wires were maintained after clinical usage.

Three-dimensional coupling between orthodontic bone remodeling and superelastic behavior of a NiTi wire applied for initial alignment

PURPOSE

NiTi wires are considered as the most appropriate wires to be used during the initial phase of orthodontic treatment. This work presents a numerical method to simulate the coupling between the orthodontic appliance and bone remodeling, which are the two mechanisms responsible for the orthodontic tooth movement.

METHODS

The superelastic behavior of a NiTi wire was integrated in a three-dimensional simulation model to reproduce the long-term bone remodeling coupled with tooth alignment using the finite element method. The orthodontic load was derived by deforming the superelastic wire in order to adopt itself to the original position of irregular teeth. Root form was extracted from cone beam tomography imaging files.

RESULTS

As a result, the teeth were aligned while the wire was recovering its initial shape. The canine was intruded by 0.53 mm, while the neighboring teeth were extruded by 0.44 and 0.46 mm. When the wire was loaded, it generated a load of 4.6 N on the bracket bonded on the canine. This force was active during the first day of the treatment. Then, the force continued to decline until the end of the correction period. The decreasing load delivered from the wire affected the teeth displacements as observed in real situations.

CONCLUSION

Despite the complexity of the presented numerical simulation, this procedure allowed the analysis of the orthodontic forces that were generated in the clinical experiments and of the biomechanical response of the periodontal support elements when using this kind of wire.

Effectiveness of two thermal activated orthodontic archwire sequences based on transition temperature range during alignment: A randomized non-controlled comparative study

INTRODUCTION

It has been suggested that heat-activated NiTi archwires (HANT) speed up crowding alleviation. HANT wires are available with different austenite finish temperatures.

OBJECTIVE

The aim of the present study was to compare the effectiveness of two alignment sequences using thermally activated archwires with different austenite activation temperatures for the correction of mandibular anterior crowding.

MATERIAL AND METHODS

The following NiTi archwire sequence was used for both groups: 0.012 in (conventional NiTi), 0.018 in (heat-activated NiTi archwires), 0.016×0.022 in (heat-activated NiTi archwires) and 0.019×0.025 in (conventional NiTi). The conventional NiTi used for both groups belongs to the same commercial brand. Two different austenite activation temperatures (35°C and 37°C) were used for the heat-activated archwires. The primary outcome was the degree of crowding correction measured on study models. The secondary outcome was crowding survival time over a six-month period. This RTC included fifty-four patients that were randomly allocated to the two different archwire sequences. A Mann-Whitney test was used to compare the groups regarding crowding alleviation. A survival curve was created using the Kaplan-Meier method to illustrate the reduction of crowding over time. A Mantel-Cox log-rank test was used to compare survival times (until correction of crowding).

RESULTS

No differences in crowding alleviation were identified between both groups (log-rank test; P=0.77).

CONCLUSIONS

The two alignment sequences with different thermal activated archwires at 35°C and 37°C achieved similar clinical results during the correction of mandibular anterior crowding.

Evolution, clinical applications, and prospects of nickel-titanium alloys for orthodontic purposes

This review article presents an evolution of the nickel-titanium wires for orthodontics, following their introduction by the pioneering studies of Andreasen. The original nonsuperelastic wires were followed by the introduction of superelastic Japanese NiTi wire by Miura and colleagues and Chinese NiTi wire by Burstone and colleagues. Subsequently, new nickel-titanium wires with true shape memory in the oral environment were introduced. Manufacturers have marketed special heat-treated wires with variable force delivery at different positions along the archwire. Ion implantation and other surface modification techniques have been used by manufacturers to reduce in vivo nickel release from the nickel-titanium wires, provide a more esthetic appearance, decrease friction, and improve corrosion resistance. The use of several research techniques to provide supporting information about the structures and transformations, mechanical properties, and clinical failure for the different types of the nickel-titanium wires are summarized. The evolution of the ADA/ISO standard for evaluation of these wires is also described. The closing section focuses on the use of surface modification and special coatings for the nickel-titanium wires, a major recent and ongoing area of active research.

A Full Diagnostic Process for the Orthodontic Treatment Strategy: A Documented Case Report

The need for extractions in orthodontic treatment has always been a controversial topic. However, to date there is not a specific clinical guideline that can help the clinicians deciding to plan an extractive or a non-extractive orthodontic treatment. In this respect, clinicians must deal with patients’ occlusal, functional, periodontal and aesthetics characteristics before planning an orthodontic treatment including extraction. Considering the absence of specific guidelines, the choice to extract teeth or not is complicated, particularly in borderline cases. In this case report, we present a borderline case of a patient with the skeletal Class III pattern and significant crowding in both arches that could be treated with or without extraction, illustrating the diagnostic and decision-making processes that were conducted for the orthodontic treatment strategy.

Comparison of force delivery of thermally activated aesthetic and non-aesthetic Ni-Ti wires: An in-vitro study

OBJECTIVE

The present study aimed to compare the force of aesthetic wires and their non-aesthetic equivalents from two commercial brands at different displacement points, during the unloading phase at 36°C.

MATERIALS AND METHODS

Forty samples (n=10) were assessed, which were presented in two groups of aesthetic wires and two groups of non-aesthetic wires from the brands GAC® (Dentsply GAC® International, NY, USA) and Aditek®(Cravinhos, SP, Brazil), with 0.016-inch gauge. The orthodontic wires were maintained at a temperature of 36°C throughout the experiment and they were subjected to the three-point bending test at a speed of 1mm/min. The unloading values were recorded as 0.5, 1.5, and 2.5mm of displacement. The data were subjected to Student's t-test and unequal variance t test, at 5% significance level.

RESULTS

During the unloading phase, the mean force was significantly higher for aesthetic wires than non-aesthetic ones, in the deflection of 2.5mm, presenting values means of 2.25N (P=.0213). In deflections of 0.5mm and 1.5mm, the orthodontic archwires did not show significant differences in force between the thermally activated wires with aesthetic coating and their non-aesthetic equivalents (P≥0.05).

CONCLUSION

It is concluded that during the unloading phase at a temperature of 36°C, the orthodontic archwires analyzed did not show significant difference in force between thermally activated wires with aesthetic coating and their non-aesthetic equivalents at most displacement points analysed, except for the deflection of 2.5mm, which showed higher values.

A comparative assessment of clinical efficiency between premium heat-activated copper nickel-titanium and superelastic nickel-titanium archwires during initial orthodontic alignment in adolescents: a randomized clinical trial

Background

To compare the clinical efficiency of premium heat-activated copper nickel-titanium (Tanzo Cu-NiTi) and NT3 superelastic NiTi during initial orthodontic alignment.

Subject and methods

A total of 50 patients were randomly allocated to 1 of 2 different archwire types (group 1, Tanzo Cu-NiTi; group 2, NT3 superelastic NiTi). Eligibility criteria included Class I or Class II malocclusion, moderate maxillary anterior crowding, and healthy periodontal condition. Impressions of the upper arches were taken before archwire placement (T0) and at every 4 weeks (T1, T2, T3, and T4). For T1 and T2 stages, 0.014-in., and for T3 and T4 stages, 0.018-in. archwires were used. The primary outcome was the alignment efficiency assessed using Little’s irregularity index. The secondary outcomes were arch width and incisor inclination changes. Data were analyzed using independent samples t test, repeated measures ANOVA, and Mann-Whitney U test. Marginal models were established for the estimation of coefficients.

Results

The anterior irregularity index reduction was mostly observed between T0 and T2 periods, which were respectively − 7.40 ± 0.50 mm (p < 0.001; 95% CI, − 8.94, − 5.85) and − 6.80 ± 0.55 mm (p < 0.001; 95% CI, − 8.49, − 5.12) for groups 1 and 2 (p < 0.001). With both wires, Little’s irregularity index decreased over time, and the difference between the groups was not significant (p = 0.581; estimated effect size, 0.011). No statistically significant difference was found between the groups in terms of intercanine and intermolar width and incisor inclination changes.

Conclusion

There were no significant between-group differences in alignment efficiency, arch width, and incisor inclination change. There was an increased alignment with 0.014-in. compared with 0.018-in. diameter archwire.

Clinical comparison of two initial arch wires (A-NiTi and Heat Activated NiTi) for amount of tooth alignment and perception of pain: A randomized clinical trial

OBJECTIVES

The aim of this study was to compare two initial arch wires, 0.014″ A-NiTi and 0.016″ Heat Activated NiTi (HANT), for amount of tooth alignment and perception of pain.

MATERIALS AND METHODS

In total, 59 orthodontic patients (21 males and 38 females) from three orthodontic clinics participated in this 2-arm, parallel-group clinical trial and were randomized to 0.014″ A-NiTi (n=30) or 0.016″ HANT groups (n=29). Patient recruitment commenced in April 2016 and ended in December 2016. Age of the patients was between 12 to 25 years with an average of 17.92±3.74 years. Eligibility criteria included permanent dentition, non-extraction treatment plan in lower arch, Irregularity Index>2 in lower arch, no systemic disease influencing pain, no chronic Non Steroid Anti Inflammatory Drug (NSAID) therapy, and no history of dental pain, mucosal ulcers or temporomandibular disorders (TMD). Blinding was applicable to the patients and outcome assessment. The primary outcome was to compare the reduction of the Irregularity Index mean from bonding sessions to 4 weeks later in these groups and the secondary outcome was evaluation of the pain according to the modified McGill Pain Questionnaire (MPQ) with Visual Analogue Scale questionnaire (VAS).

RESULTS

The mean differences of irregularity indices between the two groups are not statistically significant (95% CI: 0.39-1.03; P=0.36) and according to the questionnaire, there was no significant difference between the two groups in trigger, site, description, duration, beginning, medication, and pain reduction over time. However, the VAS scale of HANT group was significantly higher than that of A-NiTi (P=0.04).

CONCLUSION

Results from this investigation suggested that there was no clinical difference in amount of tooth alignment and perception of pain between 0.014″ A-NiTi and 0.016″ HANT wires.

Force level of small diameter nickel-titanium orthodontic wires ligated with different methods

Background

The aim of this study was to compare the deflection force in conventional and thermally activated nickel-titanium (NiTi) wires in passive (Damon Q) and active (Bioquick) self-ligating brackets (SLB) and in conventional brackets (CB) tied by two different methods: elastomeric ligature (EL) and metal ligature (ML).

Methods

Two wire diameters (0.014 and 0.016 in.) and 10 specimens per group were used. The specimens were assembled in a clinical simulation device and tested in an Instron Universal Testing Machine, with a load cell of 10 N. For the testing procedures, the acrylic block representative of the right maxillary central incisor was palatally moved, with readings of the force at 0.5, 1, 2, and 3 mm, at a constant speed of 2 mm/min and temperature of 36.5 °C.

Results

The conventional NiTi released higher forces than the thermally activated NiTi archwires in large deflections. In general, the SLB showed lower forces, while the ML had higher forces, with both showing a similar force release behavior, constantly decreasing as the deflection decreased. The EL showed an irregular behavior. The active SLB showed smaller forces than passive, in large deflections.

Conclusions

The SLB and the ML exhibit standard force patterns during unloading, while the elastomeric ligatures exhibit a randomly distributed force release behavior.

Evaluation of force released by deflection of orthodontic wires in conventional and self-ligating brackets

Introduction:

The aim of the study was to evaluate deflection forces of rectangular orthodontic wires in conventional (Morelli^TM), active (In-Ovation R^TM) and passive (Damon 3MX^TM) self-ligating brackets.

Material and Methods:

Two brands of stainless steel and nickel-titanium (NiTi) wires (Morelli^TM and GAC^TM), in addition to Ormco^TM copper-nickel-titanium wires were used. Specimens were assembled in a clinical simulation device especially designed for this study and tested in an Instron universal testing machine. For the testing procedures, an acrylic structure representative of the maxillary right central incisor was lingually moved in activations of 0 to 1 mm, with readings of the force released by deflection in unloading of 0.5, 0.8 and 1 mm at a constant speed of 2 mm/min. Inter-bracket forces with stainless steel, NiTi and CuNiTi were individually compared by two-way ANOVA, followed by Tukey’s tests.

Results:

Results showed that there were lower forces in conventional brackets, followed by active and passive self-ligating brackets. Within the brands, only for NiTi wires, the Morelli^TM brand presented higher forces than GAC^TM wires.

Conclusions:

Bracket systems provide different degrees of deflection force, with self-ligating brackets showing the highest forces.

Effect of archwire cross-section changes on force levels during complex tooth alignment with conventional and self-ligating brackets

INTRODUCTION

Our objective was to investigate the effect of archwire cross-section increases on the levels of force applied to teeth during complex malalignment correction with various archwire-bracket combinations using an experimental biomechanical setup.

METHODS

The study comprised 3 types of orthodontic brackets: (1) conventional ligating brackets (Victory Series [3M Unitek, Monrovia, Calif] and Mini-Taurus [Rocky Mountain Orthodontics, Denver, Colo]), (2) self-ligating brackets (SmartClip, a passive self-ligating bracket [3M Unitek]; and Time3 [Rocky Mountain Orthodontics, Denver, Colo] and SPEED [Strite Industries, Cambridge, Ontario, Canada], both active self-ligating brackets), and (3) a conventional low-friction bracket (Synergy [Rocky Mountain Orthodontics]). All brackets had a nominal 0.022-in slot size. The brackets were combined with 0.014-in and 0.016-in titanium memory wires, Therma-Ti archwires (American Orthodontics, Sheboygan, Wis). The archwires were tied to the conventional brackets with both stainless steel ligatures of size 0.010-in and elastomeric rings. A malocclusion of the maxillary central incisor displaced 2 mm gingivally (x-axis) and 2 mm labially (z-axis) was simulated.

RESULTS

The forces recorded when using the 0.014-in archwires ranged from 1.7 ± 0.1 to 5.0 ± 0.3 N in the x-axis direction, and from 1.2 ± 0.1 to 5.5 ± 0.3 N in the z-axis direction. When we used the 0.016-in archwires, the forces ranged from 2.6 ± 0.1 to 6.0 ± 0.3 N in the x-axis direction, and from 2.0 ± 0.2 to 6.0 ± 0.4 N in the z-axis direction. Overall, the increases ranged from 16.0% to 120.0% in the x-axis and from 10.4% to 130.0% in the z-axis directions.

CONCLUSIONS

Increasing the cross section of the wire increased the force level invariably with all brackets. Wires of size 0.014 in produced relatively high force levels, and the force level increased with 0.016-in wires.

Influence of various fluoride agents on working properties and surface characteristics of uncoated, rhodium coated and nitrified nickel-titanium orthodontic wires

OBJECTIVE

To analyze the effect of various fluoride formulations in commercially available agents on working properties of various nickel-titanium orthodontic wires.

MATERIALS AND METHODS

Uncoated (NiTi), rhodium coated (RhNiTi) and nitrified (NNiTi) wires were immersed to dH2O, MiPaste, Elmex and Mirafluor for 1 h. Unloading slope characteristics (average force, bending action of the force and average plateau length) and the percentage of useable constant force during unloading were observed. Surface roughness (Ra) was measured. SEM and EDS were used for observation of the surface.

RESULTS

NiTi had decreased loading and unloading elastic modulus (E) and yield strength (YS) after immersion to MIPaste and Mirafluor. The unloading YS decreased in the RhNiTi by the MIPaste. The loading and unloading YS of the NNiTi increased in Elmex and increased average plateau force. RhNiTi showed higher average plateau length and the percentage of useful constant force during unloading in Mirafluor and the average plateau force lowered after immersion to MIPaste. The unloading slope characteristics for NiTi were affected by all three prophylactic agents, mostly by Mirafluor, and produced significantly lower forces during both loading and unloading, similarly to the NNiTi wires. The RhNiTi had the lowest forces during both loading and unloading in MIPaste. All results were at significance; p<0.05. Difference in Ra was observed for RhNiTi after immersion to the MI Paste (p<0.001; η2=0.761).

CONCLUSION

The NiTi and NNiTi wires lose less working force when combined with Elmex. The RhNiTi improve their working properties with Mirafluor and deteriorate when combined with MiPaste.

Influence of bracket-slot design on the forces released by superelastic nickel-titanium alignment wires in different deflection configurations

Objective:

To evaluate how different bracket-slot design characteristics affect the forces released by superelastic nickel-titanium (NiTi) alignment wires at different amounts of wire deflection.

Materials and Methods:

A three-bracket bending and a classic-three point bending testing apparatus were used to investigate the load-deflection properties of one superelastic 0.014-inch NiTi alignment wire in different experimental conditions. The selected NiTi archwire was tested in association with three bracket systems: (1) conventional twin brackets with a 0.018-inch slot, (2) a self-ligating bracket with a 0.018-inch slot, and (3) a self-ligating bracket with a 0.022-inch slot. Wire specimens were deflected at 2 mm and 4 mm.

Results:

Use of a 0.018-inch slot bracket system, in comparison with use of a 0.022-inch system, increases the force exerted by the superelastic NiTi wires at a 2-mm deflection. Use of a self-ligating bracket system increases the force released by NiTi wires in comparison with the conventional ligated bracket system. NiTi wires deflected to a different maximum deflection (2 mm and 4 mm) release different forces at the same unloading data point (1.5 mm).

Conclusion:

Bracket design, type of experimental test, and amount of wire deflection significantly affected the amount of forces released by superelastic NiTi wires (P &lt; .05). This phenomenon offers clinicians the possibility to manipulate the wire's load during alignment.