An investigation of the corrosion behavior of zinc-coated stainless steel orthodontic wires: the effect of physical vapor deposition method.

BACKGROUND: Releasing of metal ions might implicate in allergic reaction as a negative subsequent of the corrosion of Stainless Steel (SS304) orthodontic wires. The aim of this study was to evaluate the corrosion resistance of zinc-coated (Zn-coated) SS orthodontic wires. METHODS: Zinc coating was applied on SS wires by PVD method. Electrochemical impedance spectroscopy (EIS), Potentiodynamic polarization tests and Tafel analysis methods were used to predict the corrosion behavior of Zn-coated and uncoated SS wires in both neutral and acidic environments. RESULTS: The values of Ecorr ,icorr and Rct ,which were the electrochemical corrosion characteristics, reported better corrosion behavior of Zn-coated SS wires against uncoated ones in both artificial saliva and fluoride-containing environments. Experimental results of the Tafel plot analyses were consistent with that of electrochemical impedance spectroscopy analyses for both biological solutions. CONCLUSION: Applying Zn coating on bare SS orthodontic wire by PVD method might increase the corrosion resistance of the underlying stainless-steel substrate.

Functional Surface Coatings on Orthodontic Appliances: Reviews of Friction Reduction, Antibacterial Properties, and Corrosion Resistance.

Surface coating technology is an important way to improve the properties of orthodontic appliances, allowing for reduced friction, antibacterial properties, and enhanced corrosion resistance. It improves treatment efficiency, reduces side effects, and increases the safety and durability of orthodontic appliances. Existing functional coatings are prepared with suitable additional layers on the surface of the substrate to achieve the abovementioned modifications, and commonly used materials mainly include metal and metallic compound materials, carbon-based materials, polymers, and bioactive materials. In addition to single-use materials, metal-metal or metal-nonmetal materials can be combined. Methods of coating preparation include, but are not limited to, physical vapor deposition (PVD), chemical deposition, sol-gel dip coating, etc., with a variety of different conditions for preparing the coatings. In the reviewed studies, a wide variety of surface coatings were found to be effective. However, the present coating materials have not yet achieved a perfect combination of these three functions, and their safety and durability need further verification. This paper reviews and summarizes the effectiveness, advantages and disadvantages, and clinical perspectives of different coating materials for orthodontic appliances in terms of friction reduction, antibacterial properties, and enhanced corrosion resistance, and discusses more possibilities for follow-up studies as well as for clinical applications in detail.

Evaluation of the Effects of Povidone Iodine and Hydrogen Peroxide Mouthwashes on Orthodontic Archwires: An In Vitro Study.

AIM: To evaluate the effects of two preprocedural mouthrinses, hydrogen peroxide (H2O2) and povidone iodine (PI) on the surface characteristics and mechanical properties of nickel-titanium (NiTi) and stainless steel (SS) orthodontic archwires. MATERIALS AND METHODS: Five wire specimens were used, each (0.016" NiTi, 0.016" SS wires, 0.016 × 0.022" NiTi and 0.016 × 0.022" SS wires) specimen was cut into 30 mm lengths and immersed in 9% of artificial saliva and 91% of two preprocedural mouthrinse solutions: 1.5% hydrogen peroxide mouthwash, 0.2% povidone-iodine mouthwash, and distilled water (control group) for 90 minutes and incubated at 37°C. The wire specimens were then subjected to a three-point bending test for mechanical testing and viewed under a scanning electron microscope (SEM) to evaluate their surface characteristics. The collected data were analyzed using one-way analysis of variance (ANOVA) and Bonferroni post hoc test. RESULTS: The results showed a significant increase in the flexural modulus (E) of Nitinol wires in povidone-iodine gargle (p < 0.05) and a significant increase in the E of stainless steel wires in hydrogen peroxide mouthwash (p < 0.05). Analysis using SEM showed varying qualitative surface changes in the form of corrosion, voids, and ridges on the wires after exposure to both the mouthwashes. CONCLUSION: Though there were significant changes in the flexural modulus of archwires for both the mouthwashes, hydrogen peroxide did not show a significant difference in the E of wires at most of the deflection intervals when compared with the other two solutions, hence, could be used in orthodontic patients as an effective preprocedural mouthrinse. CLINICAL SIGNIFICANCE: Preprocedural mouthrinses can cause surface irregularities on the wires which in turn lead to an increase in friction at the bracket-wire interface, thereby disrupting effective tooth movement and extending the orthodontic treatment time.

Prolonged water immersion alters resistance to sliding of aesthetic orthodontic coated wires.

OBJECTIVE: The objective of this study was to compare the resistance to sliding of aesthetic orthodontic coated wires after prolonged water immersion for up to 4 weeks. SETTING AND SAMPLE POPULATION: An in vitro study of commercially available orthodontic appliances. MATERIALS AND METHODS: Aesthetic coated stainless-steel wires (Parylene-coated, epoxy-coated and Teflon-coated) (0.019" × 0.025") and an uncoated control were immersed in distilled-deionized water for zero, two or four weeks at 37°C and then were subjected to resistance-to-sliding tests through a three-bracket system of sapphire ceramic brackets (0.022" × 0.028" slot) and clear-coloured elastic ligatures at a contact angle of 0° or 3°. Maximal and average resistance to sliding was analysed by a three-way analysis of variance, two general linear models and a post hoc Tukey's honest significant difference test. RESULTS: Water immersion time, contact angle, wire group and their interactions had statistically significant effects on the resistance to sliding of tested orthodontic wires. Various coated wires had distinct timely changes in the maximal and average resistance to sliding after water immersion for 2 to 4 weeks. When compared to the uncoated control in most of the experimental conditions, epoxy-coated wires had lower or non-significant differences in resistance to sliding, while Parylene-coated wire had higher resistances. CONCLUSIONS: Prolonged water immersion for weeks alters the resistance to sliding of aesthetic orthodontic wires coated with Parylene, epoxy or Teflon. Based on their resistance to sliding, different designs in orthodontic biomechanics should be considered for the different aesthetic orthodontic coated wires.

Tooth alignment and pain experience with A-NiTi versus Cu-NiTi: a randomized clinical trial.

BACKGROUND: Nickel-titanium (NiTi) archwires are routinely used for initial leveling and alignment of teeth in orthodontic treatment. This study aimed to clinically compare the level of pain and tooth alignment in orthodontic treatment with A-NiTi versus Cu-NiTi archwires. METHODS: In this parallel randomized clinical trial, 88 orthodontic patients (12-25 years) with an irregularity index > 2 mm in the anterior site of the lower dental arch who required non-extraction orthodontic treatment of the lower arch were randomized into two age- and sex-matched groups (n = 44) for treatment with A-NiTi and Cu-NiTi initial archwires. Each archwire was used for 6 weeks. After 6 weeks, the irregularity index was measured, and the level of pain was scored using the Modified McGill pain questionnaire (MPQ) and visual analog scale (VAS) according to the time of onset and duration of pain, and analgesic intake. Data were analyzed by paired t test, independent samples t test, and Chi-square test (P < 0.05). RESULTS: The irregularity index significantly decreased in both groups after 6 weeks of treatment (P < 0.001). However, the difference in this respect was not significant between the two groups (P > 0.05). Pain perception (P = 0.487), duration of pain (P = 0.546), and analgesic intake (P = 0.102) were not significantly different between the two groups either. CONCLUSION: Both A-NiTi and Cu-NiTi archwires are equally effective for tooth alignment in the anterior site of the lower dental arch and have no significant difference with regard to the level of pain experienced by patients. TRIAL REGISTRATION NUMBER: IRCT20190705044102N1 and Name of the registry: Iranian registry of clinical trials (https://irct.ir/) Date of registration: September, 26, 2019.

Pain perception of orthodontic treatment - A cross-sectional study.

OBJECTIVES: The objectives were to evaluate the intensity of pain perceived 24 hours following insertion of fixed orthodontic appliance components i-e separators, bands and brackets. METHODS: This cross-sectional study conducted at a Dental College in Karachi (July 2017-March 2018) investigated the amount of pain perceived during different stages of fixed orthodontic treatment. The inclusion criteria were healthy individuals without systemic disease, age 13-26 years, fixed orthodontic treatment candidates having healthy permanent first molars. The exclusion criteria were missing permanent first molars, patients requiring brass wire separators instead of elastomeric separators and molar tubes instead of bands, ongoing or previous periodontal disease and syndromic patients. Pain intensity was assessed in ninety eight patients using a Numeric Rating scale (NRS) at baseline (T0) before insertion, and 24 hours after insertion (T1) of a component. This procedure was repeated six times, twice each for separators, bands and brackets. Scoring was done on the NRS from 0 to 10 where 0 indicated no pain and 10 indicated worst pain possible. RESULTS: A significant difference in perceived pain was found between baseline and after 24 hours of placement of all components (P-value 0.000). Odds ratio indicated that males were at a greater risk to feel pain than females at baseline and after 24 hours of insertion of all components. Mann-Whitney U test showed that the most painful components at baseline were bands (Mean value=0.56) and after 24 hours were brackets (Mean value 6.25). CONCLUSIONS: Significant increase in pain was noted 24 hours after insertion of separators, bands and brackets. The most painful components were bands at baseline and brackets after 24 hours of insertion. There were no significant variations in pain perception based on age. However, males perceived higher pain than females both at baseline and after 24 hours.

Alignment efficiency of coaxial tubular superelastic nickel-titanium vs single-stranded superelastic nickel-titanium in relieving mandibular anterior crowding in extraction cases: A single-centre randomized controlled clinical trial.

OBJECTIVES: To compare the alignment efficiency of coaxial tubular and single-stranded 0.016" superelastic NiTi archwires in relieving mandibular anterior crowding in extraction cases and to evaluate whether alignment efficiency differed as the initial irregularity increased. SETTING AND SAMPLE POPULATION: Forty female patients aged between twelve and twenty years from the postgraduate orthodontic clinic at the authors' centre. MATERIALS AND METHODS: All patients in this single-centre, 2-arm parallel trial were randomly allocated in a 1:1 ratio and the mandibular anterior irregularity was measured from the mandibular cast at 0-, 4-, 8- and 12-week intervals using a digital calliper. RESULTS: All forty patients (mean age, 15.08 ± 2.11) completed the study with either coaxial tubular superelastic NiTi (mean age, 15.30 ± 2.36) or single-stranded superelastic NiTi (mean age, 14.85 ± 1.84). The largest mean irregularity index reduction of -4.88 ± 2.74 and -6.17 ± 2.38 in the single-stranded superelastic NiTi and the coaxial tubular superelastic NiTi groups, respectively (P = 0.122) was at 4 weeks. Student's t test and repeated measures ANOVA indicated that none of the mean comparisons were statistically significant at a 5% level. Pearson's correlation value (r) indicated no statistically significant influence of initial crowding on alignment efficiency. CONCLUSIONS: There was no statistically significant difference between the alignment efficiency of coaxial tubular superelastic NiTi and single-stranded superelastic NiTi in extraction cases, and the degree of initial crowding had no influence on the alignment efficiency.

Evaluation of slot height in Roth prescription orthodontic brackets.

The dimensional accuracy of orthodontic brackets slots is extremely important, since inaccuracy can affect orthodontic mechanics. The aim of this study was to investigate the slot heights of Roth prescription brackets from several commercial manufacturers. A total of 360 maxillary and mandibular incisor brackets from 6 different commercial models (Kirium Line, Ovation, Roth Light, Synthesis, Integra, and Miniature Twin) were selected and divided into 18 experimental groups containing maxillary central incisor, maxillary lateral incisor, or mandibular central incisor brackets (n = 20). Brackets were viewed under a scanning electron microscope to acquire a clear image of all slot edges, and slot heights were measured at 2 locations on each bracket to acquire mean values. Group means and standard deviations were calculated and compared with the manufacturer reference value of 0.5588 mm (0.0220 inch) plus or minus a tolerance level of 0.0100 mm (∼0.0004 inch). With the exception of Synthesis maxillary lateral incisor brackets (P = 0.230), all brackets had slot heights that were significantly smaller than 0.5588 mm (P < 0.05). The measured slot heights were 1.84% to 14.91% smaller than the reference value. Virtually all measured bracket slot heights were smaller than claimed by the manufacturers, with great variability within the same brand and indication, revealing a lack of precision in the fabrication process.

A new orthodontic force system for moment control utilizing the flexibility of common wires: Evaluation of the effect of contractile force and hook length.

BACKGROUND/PURPOSE: The application of an appropriate force system is indispensable for successful orthodontic treatments. Second-order moment control is especially important in many clinical situations, so we developed a new force system composed of a straight orthodontic wire and two crimpable hooks of different lengths to produce the second-order moment. The objective of this study was to evaluate this new force system and determine an optimum condition that could be used in clinics. METHODS: We built a premolar extraction model with two teeth according to the concept of a modified orthodontic simulator. This system was activated by applying contractile force from two hooks that generated second-order moment and force. The experimental device incorporated two sensors, and forces and moments were measured along six axes. We changed the contractile force and hook length to elucidate their effects. Three types of commercial wires were tested. RESULTS: The second-order moment was greater on the longer hook side of the model. Vertical force balanced the difference in moments between the two teeth. Greater contractile force generated a greater second-order moment, which reached a limit of 150 g. Excessive contractile force induced more undesired reactions in the other direction. Longer hooks induced greater moment generation, reaching their limit at 10 mm in length. CONCLUSION: The system acted similar to an off-center V-bend and can be applied in clinical practice as an unconventional loop design. We suggest that this force system has the potential for second-order moment control in clinical applications.

Wire Roughness Assessment of 0.016'' × 0.022'' the Technique Lingual Orthodontics.

OBJECTIVE: To evaluate the difference in surface roughness of stainless steel archwires of different commercial brands used in lingual orthodontics. MATERIALS AND METHODS: Precontoured arches measuring 0.016'' × 0.022'' were selected of the following brands: Tecnident, Adenta, G&H, Highland Metals Inc., Ormco, Incognito, and Ebraces. Quantitative evaluation of the surface roughness of archwires was performed by means of an atomic force microscope in contact mode. Three surface readouts were taken of each sample, analyzing areas of 20 × 20 µm. Each scan of the samples produced a readout of 512 lines, generating three-dimensional images of the wires. The analysis of variance statistical test was applied to prove significant variables (p > 0.05), with H0 being rejected and H1 accepted. RESULTS: The Incognito brand showed the lowest surface roughness. The archwires of brands Adenta, Tecnident, Highland, and Ormco showed similar values among them, and all close to these obtained by the Incognito brand. The archwires of the Ebraces brand showed the highest surface roughness, with values being close to those of the G&H Brand. CONCLUSION: There was a statistical difference in surface roughness of orthodontic archwires among the brands studied. CLINICAL SIGNIFICANCE: Companies should pay attention to the quality control of their materials, as these may directly affect the quality of orthodontic treatment.

Effect of Elastomeric Module Degradation and Ligation Methods on Kinetic Friction between NiTi or Stainless Steel Wires and Stainless Steel Brackets.

Objectives: The reduction of resistance to sliding between the archwire and bracket promotes more seamless tooth movement, leading to a faster and improved orthodontic treatment experience. This research aimed to examine how the degradation of elastomeric modules, different ligation methods, bracket-wire angle, and wire type (nickel titanium, NiTi or stainless-steel, SS) impact the kinetic friction resulting from the interaction between NiTi or SS archwires and SS brackets. Materials and Methods: The current in vitro study was conducted on nine groups, including NiTi and SS archwires with three types of ligations (O-ring, figure of 8, and SS wire ligature) and two bracket-wire angles (0˚ and 10˚). The kinetic friction in each group was measured using a Universal Testing Machine at four time intervals: baseline, day one, week one, and week four. Repeated measures ANOVA, Mauchly test of sphericity followed by the Greenhouse-Geisser test, and relevant post hoc tests were used for statistical analysis (P<0.05). Results: The authors found a decrease in kinetic friction in all types of ligations, which confirmed the effect of time on the degradation of ligation modules. The kinetic friction of figure of 8 ligations was higher than both O-ring and SS wire ligations. No difference was observed between O-ring and SS wire ligations. Furthermore, the bracket-wire angle did not affect friction. Conclusion: The authors suggest that the use of figure of 8 ligations in NiTi and SS wires should be limited due to their high friction and replaced with other types of ligations, if possible.

Influence of distal-end heat treatment in the properties of heat-activated NiTi archwires.

PURPOSE: The aim of this study was to evaluate the extent of property changes caused by heating the distal portion of heat-activated nickel-titanium (NiTi) wires. METHODS: Forty preformed heat-activated NiTi archwires (3M Unitek, Monrovia, CA, USA) with a nominal cross-section of 0.018″ were used in this study. The archwires were divided into a control group, not submitted to heat treatment and, thus, maintaining the as-received properties, and an experimental group, in which the archwires were submitted to heat treatment for distal bending at one end. Wire segments of control and experimental groups were submitted to differential scanning calorimetry (DSC) and Vickers microhardness measurements. RESULTS: The DSC results suggest local recrystallization and precipitate dissolution at the heat-treated tip, which decreases as the distance to the wire's tip increases. Vickers microhardness tests revealed significant changes for distances between 6 and 8 mm from the wire's tip. Heating the distal portion of heat-activated NiTi archwires should be performed with care since this clinical procedure may compromise the performance of these wires to a distance of 8 mm from the archwire end. CONCLUSION: Heat treatment for distal bending in heat-activated NiTi archwires may be performed, with little impact on the areas adjacent to heat treatment. In cases presenting molars requiring significant orthodontic corrections, it should be preferred to apply other techniques to avoid archwire sliding, such as crimpable stops, or to have flame control to avoid placing a heat-treated section in the tubes of these molars.

Novel approach for characterizing clinical load application of superelastic orthodontic wires.

OBJECTIVE: Current standardized in vitro bending experiments for orthodontic archwires cannot capture friction conditions and load sequencing during multi-bracket treatment. This means that clinically relevant forces exerted by superelastic wires cannot be predicted. To address these limitations, this study explored a novel test protocol that estimates clinical load range. METHODS: The correction of a labially displaced maxillary incisor was simulated using an in vitro model with three lingual brackets. Deflection force levels derived from four different protocols were designed to explore the impact of friction and wire load history. These force levels were compared in nickel-titanium (NiTi) archwires with three commonly used diameters. The unloading path varied between protocols, with single or multiple sequences and different load orders and initial conditions. RESULTS: Deflection forces from the new protocol, employing multiple continuous load/unload cycles (CCincr), consistently exceeded those from the conventional protocol using a single continuous unloading path (CUdecr). Mean differences in plateau force ranged from 0.54 N (Ø 0.014" wire) to 1.19 N (Ø 0.016" wire). The CCinr protocol also provided average force range estimates of 0.47 N (Ø 0.012" wire), 0.89 N (Ø 0.014" wire), and 1.15 N (Ø 0.016" wire). SIGNIFICANCE: Clinical orientation towards CUdecr carries a high risk of excessive therapeutic forces because clinical loading situations caused by friction and load history are underestimated. Physiological tooth mobility using NiTi wires contributes decisively to the therapeutic load situation. Therefore, only short unloading sequences starting from the maximum deflection in the load history, as in CCincr, are clinically meaningful.

Orthodontic Wires: A 12-Year Bibliometric Study.

Aims and Objectives: To perform a bibliometric study to identify and evaluate articles associated with "orthodontic wires" indexed in six databases (PubMed, Embase, Cochrane, Scopus, Lilacs, and Google Scholar) from 2010 to 2022. Materials and Methods: The search strategy in PubMed combined different medical subject heading terms with free-text words and was adjusted for each selected database. The retrieved documents were original English articles containing the keywords used in the search strategies related to orthodontic wires. Collected data consisted of journal name, nationality, field, JIF-2 and JIF-5, SJR, CiteScore, Q and H-index, and categorization of the study. Results: In total, 417 articles were retrieved from the initial search. After the exclusion criteria, 257 articles remained. The most common theme was mechanical properties, with basic studies as the main categorization. Conclusions: This bibliometric survey provides an overview of orthodontic wires publications that might help orthodontists to understand the tendency of the studies on this subject. The retrieved papers were published in 100 journals, including 15 orthodontic journals, mainly in the first and second quartiles. Europe and America were the continents with the highest number of papers. The United States was the country with the highest number of journals on the topic. AJODO presented the highest h-index among the retrieved orthodontic journals. Brazil represented the principal institutions of origin of the listed articles. There was a tendency to increase the number of publications on orthodontic wires over the years. These findings indicate that research on orthodontic wires is still contemporary and relevant.

Sterilizing orthodontic appliances: A systematic review and meta-analysis on the available methods.

Infection control is essential to protect both the doctor and the patient by preventing the spread of infectious diseases. There is no exception in the field of dentistry, particularly in orthodontics, where numerous appliances are used for a variety of functions and also because the mouth cavity has the highest concentration of bacteria of any body part. Through this systematic review, we aimed to assess the various methods of sterilization employed in an orthodontic setting. Using relevant keywords, reference searches, and citation searches, the databases such as PubMed, MEDLINE, Web of Science, Cochrane, and Scopus were all searched; a total of 206 documents were found, of which 113 were initially selected. The remaining 23 distinct papers were initially made available after 90 publications that were identical to or similar to one another were eliminated. The final selection was made from eight documents that met all inclusion and exclusion requirements. The existing methods of sterilization were found to be competent in dealing with the microorganisms found in a typical orthodontic setting. The chemical method of sterilization was the norm in most of the studies that we assessed, with glutaraldehyde and peracetic acid (PAA) being the most commonly employed compounds for disinfection. PROSPERO Registration Number: CRD42022380831.

Effect of Different Forms of Fluoride Application on Surface Roughness of Rhodium-Coated NiTi Orthodontic Wires: A Clinical Trial.

Objectives: This study aimed to assess the effect of different forms of fluoride application on surface roughness of rhodium-coated nickel-titanium (NiTi) orthodontic wires. Materials and Methods: This randomized clinical trial was conducted on 15 patients randomly divided into three groups: toothbrush with Oral-B toothpaste only, Oral-B toothpaste, and daily mouthwash, Oral-B toothpaste, and sodium fluoride gel. The surface roughness indices of orthodontic wires including arithmetic mean height (Sa), root mean square height, root mean square gradient, developed interfacial area ratio (Sdr) and maximum surface height were measured by atomic force microscopy at baseline and after 6 weeks of application in the patients' mouths. Data were analyzed by paired t-test, ANOVA, Games-Howell, and Tukey-HSD tests (P<0.05). Results: All surface roughness parameters in all three groups showed a significant increase after intervention, except for Sa in the toothpaste-only group (P=0.057) and Sdr in the sodium fluoride gel group (P=0.064). Conclusion: The surface roughness of rhodium-coated NiTi orthodontic wires increases following the use of different forms of fluoride.

Alignment efficiency of heat activated and superelastic nickel-titanium archwires in orthodontic patients over three months: A Single-center, randomized clinical trial.

OBJECTIVE: The aim of this 2-arm parallel study was to evaluate the alignment efficiency of heat-activated nickel-titanium (NiTi-TE) and superelastic nickel titanium (NiTi-PSE) archwires over the first 3 months of orthodontic treatment and compare these groups. SETTING AND SAMPLE POPULATION: Randomized, double-blind, controlled, single-center trial in 52 patients with fixed orthodontic appliances from an orthodontic graduate program in the permanent dentition and moderate crowding in the lower arch. MATERIAL AND METHODS: Patients were randomly allocated to one of two interventions: NiTi-TE and NiTi-PSE archwires, 0.014-inch (3M Unitek™, CA, USA) with a follow-up period of 3 months. The primary outcome was the alignment efficiency determined by the reduction in Little's irregularity index (mm), measured in three points, T0: before the start of orthodontic treatment, T1: 1 month later, T2: 2 months later, T3: 3 months later. Data were analyzed using independent sample t tests and repeated measures ANOVA. RESULTS: 52 patients (NiTi-TE n = 26; NiTi-PSE n = 26) were randomized and analyzed (average age: 21.73; standard deviation (SD): 6.07; average lower anterior irregularity: 5.20; SD: 0.76) for intention-to-treat (ITT) analysis. No statistically significant differences between the groups were found (mean of the differences: T1: 0.20; 95% CI: -0.558; 0.958; T2: 0.49: 95% CI: -0.339; 1.319; T3: 0.33; 95% CI: -0.308; 0.968). The resolution of crowding with each of the wires was significant (P < 0.0001) at all times. Twelve participants (2 treated with NiTi-TE and 10 treated with NiTi-PSE) lost follow-up due to face-to-face dental-procedures restrictions during the COVID-19 pandemic, the missing data was imputed. CONCLUSIONS: NiTi-TE and NiTi-PSE wires of 0.014-inch were similar in their clinical efficiency for the resolution of crowding during the first 3 months of orthodontic treatment. REGISTRATION: Clinical Trials NCT03256279.

Metallurgy in orthodontic-A systematic review and meta-analysis on the types of metals used.

A variety of metals and alloys are employed in the field of orthodontics, primary of which happen to be the construction of wires. Through this systematic review, we aimed to assess the various metallurgical characteristics of the said metals and alloys. Four hundred and eighty-two documents in total were found after a thorough search of the online journals, and 169 of the papers were initially chosen. Ultimately, 16 documents were selected that satisfied the necessary inclusion and exclusion criteria, primarily in vitro studies, literature reviews, and comparative analyses. NiTi alloy was found to be the most commonly used alloy in construction of orthodontic wires across all the studies that we had selected for our review. It also had better performance and consistency in terms of its usage as depicted by the meta-analysis performed, with stainless steel wires being a close second primarily due to its lesser cost compared to the former. Metallurgy and orthodontics are inextricably linked with one another. The various components of orthodontics such as wires, pliers, and other instruments utilize the metallurgical characteristics of metals and alloys that are specially prepared for the challenges of this field. PROSPERO Registration Number: CRD42022378444.

Comparison of the mechanical properties and surface topography of as-received and as-retrieved Copper-Nickel-Titanium arch wires: An ex-vivo study.

AIM: The mechanical and surface characteristics of Copper NiTi wires following intraoral aging in an important topic. This ex-vivo study is designed to assess the three most important mechanical properties; torsional stiffness, 3-point bending and surface hardness of the as-received Copper NiTi orthodontic archwires and compare them to the retrieved ones. MATERIAL AND METHODS: In this study, 50 round CuNiTi (0.016 inch) and 50 rectangular (0.018×0.025 inch) CuNiTi orthodontic wires (American Orthodontics, Tanzo Copper Nickel Titanium, Sheboygan, WI) were tested. The groups were as follow: 25 as-received 0.016 inch round CuNiTi archwires (group 1), 25 as-retrieved 0.016 inch round CuNiTi archwires (group 2), 25 as-received 0.018×0.025 inch rectangular CuNiTi archwires (group 3), and 25 as-retrieved 0.018×0.025 inch rectangular CuNiTi archwires (group 4). The physical properties of all of the samples were examined using Vickers hardness, bending and torsional tests. The Kolmogorov-Smirnov test was applied to assess the normal distribution of data. An independent t-test was used to compare the variables between the groups. RESULTS: The results showed that the hardness does not significantly differ between the as-received and as-retrieved archwires in both 0.016 and 0.018×0.025 inch archwires (P< 0.05). The bending test of the round wires showed that the values of the activation forces in the as-received ones were significantly higher than those of the as-retrieved (P=0.00). The torsional and bending test results of rectangular wires showed that the amounts of forces exerted from the as-retrieved archwires were significantly higher than the new archwires (P=0.00). CONCLUSIONS: Round CuNiTi archwires could be retied in the succeeding visits. However, the bending activation that declines significantly should be took into consideration. On the other hand, since bending and torsion activation of CuNiTi rectangular archwires increased after intraoral use, these wires should be retied cautiously.

Evaluation of surface-modified orthodontic wires by different concentration and dipping duration of titanium oxide (TiO2) nanoparticles.

OBJECTIVE: To evaluate in-vitro surface characteristics and frictional properties of orthodontic stainless steel and beta-titanium archwires after surface modification with different concentrations and coating time of titanium oxide (TiO2) nanoparticles by Sol-gel dip coating method. MATERIALS AND METHODS: The experiment was carried out with 4 different concentrations (1:2, 1:4, 1:6, and 1:8) and three different dipping durations (24 hours, 48 hours, and 72 hours) over ten main test groups of SS and TMA archwires with uncoated wires acting as control in both dry and wet conditions. Phase analysis and surface characterization of TiO2 was analyzed by X-ray Diffractometry, surface evaluation with the help of scanning electron microscopy (SEM), and frictional characteristics were evaluated. RESULTS: Among all the concentrations 1:6 ratio with 48 hours of dipping duration showed better surface characteristics. A statistically significant difference in frictional coefficient was observed in both SS and TMA wires than their respective controls (p = 0.001). Intragroup comparison among SS and TMA groups showed that groups with 1:6 ratio and 48 hours dipping duration had least frictional coefficient in both dry and wet conditions (p = 0.001). Intergroup comparison between SS and TMA showed that SS group had significantly reduced friction than TMA (p = 0.001) except in few groups. CONCLUSION: TiO2 nanoparticle with a concentration ratio of 1:6 and 48 hours dipping duration is recommended for surface modification of orthodontic archwires.