Effects of Different Sterilization Methods on Orthodontic Wires: An In Vitro Study.

Objective: The purpose of this study was to determine the effect of common methods of sterilization on the tensile strength of Beta titanium, Stainless steel, Australian Stainless steel, Copper Nickel-Titanium, and Nickel-Titanium wires. It also aimed to evaluate the changes in tensile strength values caused by repeated cycles of sterilization. Materials and Methods: A sample of 225 orthodontic wires, i.e., beta-titanium, stainless steel, Australian stainless steel, copper nickel-titanium, and nickel-titanium wires, were collected from different manufacturers. These wires were divided into three groups, which consists of Groups 1, 2, and 3. Four methods of sterilization used in this study were as follows: (i) autoclave (250°F for 20 min), (ii) dry heat sterilization (375°F for 20 min), (iii) ethylene oxide sterilization (54°C for 4 hrs), and (iv) 2.45% acidic glutaraldehyde (10 hrs). Results: The results of this study showed that there was increase in tensile strength of beta-titanium and nickel-titanium wires using autoclave and dry heat sterilization. No statistically significant difference in tensile strength of stainless steel and Australian stainless steel archwires. The tensile strength of copper nickel-titanium wires decreased following 0, 1, and 5 cycles of sterilization. Conclusion: The lack of statistically significant differences established in the study of new and sterilized orthodontic archwires gives us reason to conclude that the orthodontic arch wires can be sterilized because the sterilizing processes do not affect their tensile strength and the orthodontists could thus ensure the maximum safety of their patients.

Comparative evaluation of frictional characteristics between nano coated and non coated orthodontic brackets and arch wire configuration-An experimental in vitro study.

OBJECTIVE: To compare and assess the coefficient of frictional resistance between nano-coated orthodontic brackets and orthodontic archwires with conventional orthodontic brackets and archwires. METHODOLOGY: In this experimental study, 128 samples were divided into 4 groups consisting of 32 orthodontic wires and brackets in each group. The samples were randomly allocated into GROUP A- ZNO nanoparticle coated archwires and brackets, GROUP B ZNO nanoparticle coated bracket and conventional archwire, GROUP C-ZNO nanoparticle coated archwire and conventional bracket, and GROUP D- conventional archwire and bracket after positioning them on special jigs frictional resistance was studied and evaluated. Bon - Ferroni test was used for inter group comparison and one way ANOVA was used for intr-group comparison. RESULTS: The lowest mean frictional resistance is seen with Group A (nanocoated archwire with nanocoated bracket) N = 0.3401 ± 0.420; and highest with Group D (conventional brackets with conventional archwires) N = 0.8413 ± 0.60. a significant difference in mean frictional resistance was observed between the groups (P ≤ 0.01). The frictional resistance for the groups was in the following order from lowest to highest: group A < B < C < D. CONCLUSION: The study showed decreased friction in ZNO nanoparticle coated archwires and brackets than conventional archwires and brackets.

Mechanical Properties and Potential Clinical Implications of Improved Superelastic Orthodontic Archwires: An Observational Study.

BACKGROUND: Superelastic materials have gained popularity due to their ability to maintain a constant force over a prolonged period during orthodontic treatment. However, high hysteresis and frictional properties had limited the use of superelastics as archwire material that demanded the need for improved superelastic orthodontic archwires with enhanced mechanical properties. AIM: The present study aimed to investigate the differences in mechanical properties and frictional resistance of improved superelastic orthodontic archwires against conventional archwires and to evaluate their potential implications in clinical orthodontic practice. MATERIALS AND METHODS: A total of 45 samples with 15 in each category respectively from low hysteresis superelastic archwire (L&H Titan; Tomy Inc., Tokyo, Japan), nickel-titanium (NiTi) archwires (Ormco, Brea, CA, USA) and NiTi with copper (CuNiTi) archwires (Ormco) of equal diameter (0.016 x .022 inches) and length (10 cm) were randomly assigned in combination among metal and ceramic orthodontic brackets group. The frictional properties of the archwires were measured using a universal testing machine (Instron, Norwood, MA, USA) equipped with a custom-made jig. The load-displacement data were recorded, and other mechanical properties that included tensile strength, compressive strength and deflective force at 4mm were also evaluated. The data were analysed using independent Student t-tests to compare the mean frictional resistance of the three archwires followed by analysis of variance (ANOVA) to evaluate differences between the means with p-value of less than 0.05 considered as statistically significant. RESULTS: The improved superelastic wires had the least frictional resistance among the three archwires tested. Further intergroup comparison to evaluate differences between the frictional resistance means among the three archwire categories with two orthodontic brackets groups revealed a significant difference at p<.05. Pairwise comparison also showed significant differences with higher frictional resistance between metal brackets and low hysteresis superelastic archwire category than ceramic brackets and NiTi with copper archwires (.0003) and ceramic brackets with NiTi archwires category (.003) respectively. The lowest deflective force at 4mm with better tensile and compressive strength was seen with the improved superelastic wires. CONCLUSION: The results of this study suggest that low hysteresis superelastic archwires have lower frictional forces when combined with metal orthodontic brackets compared with ceramic orthodontic brackets. Better tensile strength with least compressive strength and deflective forces at 4mm of testing among low hysteresis L&H Titan superelastic archwire than CuNiTi and NiTi archwires was observed making them potentially advantageous for orthodontic applications.

Effect of Fluoride Content of Mouthwashes on the Metallic Ion Release in Different Orthodontics Archwires.

Metal ion release studies were carried out on three of the most commonly used orthodontic wires in the clinic: austenitic stainless steel, Ti-Mo, and superelastic NiTi, using three mouthwashes with different fluoride concentrations: 130, 200, and 380 ppm. Immersions were carried out in these mouthwashes at 37 °C for 1, 4, 7, and 14 days, and the ions released were determined by inductively coupled plasma-mass spectrometry (ICP-MS). All wires were observed by scanning electron microscopy (SEM). The results showed a moderate ion release in the stainless steel wires, with nickel and chromium values of 500 and 1000 ppb in the worst conditions for the wires: concentrations of 380 ppm fluoride and 14 days of immersion. However, in the Ti-Mo and NiTi alloys, an abrupt change in release was observed when the samples were immersed in 380 ppm fluoride concentrations. Titanium releases in Ti-Mo wires reached 200,000 ppb, creating numerous pits on the surface. Under the same conditions, the release of Ni and Ti ions from the superelastic wires also exceeded 220,000 ppb and 180,000 ppb, respectively. This release of ions causes variations in the chemical composition of the wires, causing the appearance of martensite plates in the austenitic matrix after 4 days of immersion. This fact causes it to lose its superelastic properties at a temperature of 37 °C. In the case of immersion in 380 ppm mouthwashes for more than 7 days, rich-nickel precipitates can be seen. These embrittle the wire and lose all tooth-correcting properties. It should be noted that the release of Ni ions can cause hypersensitivity in patients, particularly women. The results indicate that the use of mouthwashes with a high content of fluoride should not be recommended with orthodontic archwires.

Evaluation of the Effect of Different Types of Fluoride on Tensile Properties and Surface Roughness of Different Titanium-Based Archwires: An In vivo Study.

OBJECTIVES: The purpose of the study was to evaluate the effect of different types of fluoride on tensile properties and surface roughness of titanium based archwires clinically. MATERIALS AND METHODS: Three groups of archwires, namely nickel-titanium (NiTi), heat activated NiTi, and TMA was evaluated clinically. Each group comprised four subgroups, namely as received group, nonfluoride control group, APF gel group (received one application of 1.23% APF gel), and sodium fluoride mouthwash group (patients rinsed twice daily with 0.2% sodium fluoride mouthwash). All the archwires were removed after 3 weeks of clinical use and evaluated for surface roughness with three dimensional optical profiler. Tensile strength and elongation rate was determined with Instron universal testing machine. RESULTS: NiTi, heat activated NiTi, and TMA archwires with APF gel application showed the highest reduction in tensile strength and elongation rate and highest value for surface roughness, followed by sodium fluoride mouthwash group and finally wires without fluoride application. NiTi wires had the highest reduction in tensile strength with APF gel followed by heat activated NiTi and TMA. CONCLUSION: APF gel with highest concentration of fluoride caused most degradation in the tensile properties and surface roughness of titanium based arch wires.

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.

Evaluation of the fit of preformed nickel titanium arch wires on normal occlusion dental arches.

AIM: To determine the fits of preformed nickel titanium (NiTi) archwires on dental arches with normal occlusion. METHODS: Forty sets of upper and lower plaster models were obtained from men and women with Class I occlusions. Preformed 0.016″ × 0.022″ NiTi archwires from Rocky Mountain Orthodontics (RMO), 3 M Unitek, Ormco, and Dentaurum were evaluated in terms of their fits on dental arches from male, female, and combined cases. Data were analyzed by using fourth- and sixth-order polynomial equations, analysis of variance (ANOVA), and the Duncan post hoc test. RESULTS: In the upper arches, the best fit and least error were obtained with RMO Ovoid and Ormco Orthos Large archwires for male cases, but with 3 M Orthoform LA archwires for female and combined cases. In the lower arches, the best fit and least error were obtained with Ormco Orthos Large for male cases, with 3 M Orthoform LA and RMO Normal for female cases, and with 3 M Orthoform LA, RMO Normal, Ormco Orthos Large, and Ormco Orthos Small for combined cases. When both dental arches were matched, Ormco Orthos Large was the best wire for male cases. 3 M Orthoform LA was the best wire for female and combined cases. CONCLUSIONS: Using an archwire form with the best fit to the dental arch should produce minimal changes in the dental arch form when NiTi wires are used and require less customization when stainless-steel wires are used.

Simple way of recording dental arch forms.

Like finger prints each individual has a unique dental arch form design. Recording patient's dental arch form may be required in various fields in dentistry be it longitudinal studies for evaluating growth, forensic dentistry and most importantly in orthodontic practice for fabricating arch wires for individual patients. An easy and practical method to obtain individual arch form for each patient is explained.

A comparative study of bio degradation of various orthodontic arch wires: an in vitro study.

BACKGROUND: Orthodontic wires are the corner stones of the science and art of orthodontics and they remain in the patient's mouth for a prolonged period of 18-24 months. It is but natural to expect that they will undergo some biodegradation when in the oral environment during that period. This study aims to compare the biodegradation characteristics of four different orthodontic wires, stainless steel, nickel titanium (NiTi), titanium molybdenum alloy (TMA), and copper NiTi and to assess whether these biodegradation products, are within acceptable limits. MATERIALS AND METHODS: This study involved the incubation of four different wires in artificial saliva and analyzing the amount of metal released from them at the end of a 28 days study period. The metals analyzed for where nickel, chromium, copper, cobalt, manganese, iron, molybdenum, and titanium. The artificial saliva was changed on days 7, 14, and 21 to prevent the saturation of metals in the artificial saliva. At the end of 28 days, these four samples of artificial saliva of each wire were mixed together and analyzed for the eight metals using an inductively coupled plasma spectroscope. RESULTS: The results showed only the release of nickel, chromium, and iron from stainless steel wire, nickel from NiTi wire, nickel, and chromium from copper NiTi and none from TMA wire. CONCLUSION: The metals released from arch wires are of such minute quantities to be of any biologic hazard. The amount of metals released is well within acceptable biocompatible limits. Though this study has analyzed the biodegradation of various orthodontic wires, orthodontic wires are never used alone in mechanotherapy. Orthodontic wires along with multiband appliance system with which it is always used and in combination with accessories like face bows may release more metals.

Comparison of Superelasticity of Nickel Titanium Orthodontic Arch wires using Mechanical Tensile Testing and Correlating with Electrical Resistivity.

BACKGROUND: Application of light and continuous forces for optimum physiological response and least damage to the tooth supporting structures should be the primary aim of the orthodontist. Nickel titanium alloys with the properties of excellent spring back, super elasticity and wide range of action is one of the natural choices for the clinicians to achieve this goal. In recent periods, various wire manufacturers have come with a variety of wires exhibiting different properties. It is the duty of the clinician to select appropriate wires during various stages of treatment for excellent results. For achieving this evaluation of the properties of these wires is essential. MATERIALS & METHODS: This study is focussed on evaluating the super elastic property of eight groups of austenite active nickel titanium wires. Eight groups of archwires bought from eight different manufacturers were studied. These wires were tested through mechanical tensile testing and electrical resistivity methods. RESULTS: Unloading curves were carefully assessed for superelastic behaviour on deactivation. Rankings of the wires tested were based primarily upon the unloading curve's slope Conclusion: Ortho organisers wires ranked first and superior, followed by American Orthodontics and Ormco A wires. Morelli and GAClowland NiTi wires were ranked last. It can be concluded that the performance of these wires based on rankings should be further evaluated by clinical studies. How to cite this article: Sivaraj A. Comparison of Superelasticity of Nickel Titanium Orthodontic Arch wires using Mechanical Tensile Testing and Correlating with Electrical Resistivity. J Int Oral Health 2013; 5(3):1-12.

The comparison of frictional resistance in titanium, self-ligating stainless steel, and stainless steel brackets using stainless steel and TMA archwires: An in vitro study.

AIM: The aim of the study was to compare the frictional resistance of titanium, self-ligating stainless steel, and conventional stainless steel brackets, using stainless steel and titanium molybdenum alloy (TMA) archwires. MATERIALS AND METHODS: We compared the frictional resistance in 0.018 slot and 0.022 slot of the three brackets - titanium, self-ligating stainless steel, and conventional stainless steel - using stainless steel archwires and TMA archwires. An in vitro study of simulated canine retraction was undertaken to evaluate the difference in frictional resistance between titanium, self-ligating stainless steel, and stainless steel brackets, using stainless steel and TMA archwires. RESULTS AND CONCLUSION: We compared the frictional resistance of titanium, self-ligating stainless steel, and conventional stainless steel brackets, using stainless steel and TMA archwires, with the help of Instron Universal Testing Machine. One-way analysis of variance (ANOVA), Student's "t" test, and post hoc multiple range test at level of <0.05 showed statistically significant difference in the mean values of all groups. Results demonstrated that the titanium, self-ligating stainless steel, and stainless steel brackets of 0.018-inch and 0.022-inch slot had no significant variations in frictional résistance. The self-ligating bracket with TMA archwires showed relatively less frictional resistance compared with the other groups. The titanium bracket with TMA archwires showed relatively less frictional resistance compared with the stainless steel brackets.

Clinical variability in arch wires: a preliminary study evaluating mechanical and surface characteristics of two different sized rectangular stainless steel wires.

Experimental characterization of arch wires has been performed in many previous studies; however with the advent of new arch wire materials being introduced, some new experimental methods and characterization are required. Since literature is available for comparison, this paper examines mechanical and physical characteristics of steel arch wires to quantify their variability in engineering terms. Furthermore, the effect of wire size on properties was evaluated using two of the most common wire sizes. Finally, manufacturing consistency was verified by testing samples from different lots.