Initial arch wires used in orthodontic treatment with fixed appliances.

BACKGROUND: Initial arch wires are the first arch wires to be inserted into the fixed appliance at the beginning of orthodontic treatment and are used mainly for the alignment of teeth by correcting crowding and rotations. With a number of different types of orthodontic arch wires available for initial tooth alignment, it is important to understand which wire is most efficient, as well as which wires cause least amount of root resorption and pain during the initial aligning stage of treatment. This is an update of the review entitledInitial arch wires for alignment of crooked teeth with fixed orthodontic braces, which was first published in 2010. OBJECTIVES: To assess the effects of initial arch wires for the alignment of teeth with fixed orthodontic braces, in terms of the rate of tooth alignment, amount of root resorption accompanying tooth movement, and intensity of pain experienced by patients during the initial alignment stage of treatment. SEARCH METHODS: Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 5 October 2017), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, 2017, Issue 9), MEDLINE Ovid (1946 to 5 October 2017), and Embase Ovid (1980 to 5 October 2017. The US National Institutes of Health Trials Registry (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases. SELECTION CRITERIA: We included randomised controlled trials (RCTs) of initial arch wires to align teeth with fixed orthodontic braces. We included only studies involving participants with upper or lower, or both, full arch fixed orthodontic appliances. DATA COLLECTION AND ANALYSIS: Two review authors were responsible for study selection, 'Risk of bias' assessment and data extraction. We resolved disagreements by discussion between the review authors. We contacted corresponding authors of included studies to obtain missing information. We assessed the quality of the evidence for each comparison and outcome as high, moderate, low or very low, according to GRADE criteria. MAIN RESULTS: For this update, we found three new RCTs (228 participants), bringing the total to 12 RCTs with 799 participants. We judged three studies to be at high risk of bias, and three to be at low risk of bias; six were unclear. None of the studies reported the adverse outcome of root resorption. The review assessed six comparisons.1. Multistrand stainless steel versus superelastic nickel-titanium (NiTi) arch wires. There were five studies in this group and it was appropriate to undertake a meta-analysis of two of them. There is insufficient evidence from these studies to determine whether there is a difference in rate of alignment between multistrand stainless steel and superelastic NiTi arch wires (mean difference (MD) -7.5 mm per month, 95% confidence interval (CI) -26.27 to 11.27; 1 study, 48 participants; low-quality evidence). The findings for pain at day 1 as measured on a 100 mm visual analogue scale suggested that there was no meaningful difference between the interventions (MD -2.68 mm, 95% CI -6.75 to 1.38; 2 studies, 127 participants; moderate-quality evidence).2. Multistrand stainless steel versus thermoelastic NiTi arch wires. There were two studies in this group, but it was not appropriate to undertake a meta-analysis of the data. There is insufficient evidence from the studies to determine whether there is a difference in rate of alignment between multistrand stainless steel and thermoelastic NiTi arch wires (low-quality evidence). Pain was not measured.3. Conventional NiTi versus superelastic NiTi arch wires. There were three studies in this group, but it was not appropriate to undertake a meta-analysis of the data. There is insufficient evidence from these studies to determine whether there is any difference between conventional and superelastic NiTi arch wires with regard to either alignment or pain (low- to very low-quality evidence).4. Conventional NiTi versus thermoelastic NiTi arch wires. There were two studies in this group, but it was not appropriate to undertake a meta-analysis of the data. There is insufficient evidence from these studies to determine whether there is a difference in alignment between conventional and thermoelastic NiTi arch wires (low-quality evidence). Pain was not measured.5. Single-strand superelastic NiTi versus coaxial superelastic NiTi arch wires. There was only one study (24 participants) in this group. There is moderate-quality evidence that coaxial superelastic NiTi can produce greater tooth movement over 12 weeks (MD -6.76 mm, 95% CI -7.98 to -5.55). Pain was not measured.6. Superelastic NiTi versus thermoelastic NiTi arch wires. There were three studies in this group, but it was not appropriate to undertake a meta-analysis of the data. There is insufficient evidence from these studies to determine whether there is a difference in alignment or pain between superelastic and thermoelastic NiTi arch wires (low-quality evidence). AUTHORS' CONCLUSIONS: Moderate-quality evidence shows that arch wires of coaxial superelastic nickel-titanium (NiTi) can produce greater tooth movement over 12 weeks than arch wires made of single-strand superelastic NiTi. Moderate-quality evidence also suggests there may be no difference in pain at day 1 between multistrand stainless steel arch wires and superelastic NiTi arch wires. Other than these findings, there is insufficient evidence to determine whether any particular arch wire material is superior to any other in terms of alignment rate, time to alignment, pain and root resorption.

Modificaciones cefalométricas esqueletales en pacientes Clase II División 1 tratados con Aparatología Bimler / Skeletals cefalometrics changes in Class II Division 1 patients treated with Bimler Appliance

Introducción: Durante el crecimiento y desarrollo del niño pueden aparecer desarmonías esqueletales a nivel del macizo cráneo-facial. Entre estas se encuentra el Síndrome de Clase ll División 1, siendo el avance mandibular una de las alternativas para su corrección. Con este fin el Dr. Bimler diseñó un aparato que permite una mejor adaptación del paciente. Objetivo: Describir las modificaciones cefalométricas esqueletales que se producen con el uso del Modelador Elástico, en el tratamiento del Síndrome de Clase II División 1. Material y Método: Se realizó un estudio observacional, descriptivo y retrospectivo, el universo quedó constituido por 33 Historias Clínicas de pacientes que presentaban esta maloclusión y que fueron tratados con el Modelador Elástico Tipo A. Resultados: El ángulo total del Perfil disminuyó su promedio inicial de 14.6 a 11.8 mm y la Profundidad Facial aumentó en 4,3 mm. La Profundidad maxilar aumentó en 3,2mm; la Diagonal de Mandíbula y la Altura Facial Suborbital en 11.1mm y 4, 3 mm respectivamente, mientras el resalte esquelético se redujo en 1.6 mm. El 80 poe ciento de los varones y 72.3 por ciento de las hembras habían transformado su perfil a recto. Conclusiones: Con el uso del Modelador Elástico Tipo A en el tratamiento del Síndrome de Clase II División 1 las variables cefalométricas muestran cambios favorables hacia la corrección de las desarmonías esqueletales, al producirse unareducción significativa del resalte esquelético, lo cual contribuye a que el perfil de los pacientes sea más ortognático(AU)

Introduction: During children’s growth and development, disharmonies may occur at the level of facial-skull. Among these is Class II Division 1 Syndrome, being mandibular progress one of the alternatives for its correction. With this aim, Dr. Bimler designed a device that allows a better adaptation of the patient. Objective: Describe the skeletal cephalometric changes that occur with the use of the Elastic Modeling, in the treatment of Class II Division 1 Syndrome. Materials and Methods: An observational, descriptive and retrospective study were carried out, the work universe was made from 33 clinical records, all of them belong to patient with this anaraxia, treated with Bimler appliance Type A. Results: The total profile angle diminished its initial average from 14.6 to 11.8 mm., the maxillary depth increased in 3,2mm; the Jaw Diagonal and the Suborbital Facial Height increased too in 11.1mm and 4, 3 mm respectively, whereas the skeletal ledge decreased in 1.6 mm. 80 percent of the males and 72.3 percent of the females had transformed their profile to straight. Conclusions: With the use of Elastic Modeler Type A in the treatment of Class II Division 1 Syndrome, cephalometric variables show favorable changes towards the correction of skeletal disharmonies, resulting in a significant reduction of the skeletal ledge, which contributes to the more orthognathic profile of patients(AU)

Study of the adaptability of preformed orthodontic archwires to the average dental arch form of a Moroccan population.

INTRODUCTION: The aim of this study is to determine which commercially available preformed archwires offer a good fit with the average dental arch form of our sample. MATERIALS AND METHOD: We measured the dental arch parameters of sample 1 comprising 30 dental models and compared them with the dimensions of 25 archwires (sample 2) offered for sale by orthodontic suppliers. RESULTS AND DISCUSSION: Of the 25 archwires tested, 10 correspond perfectly to the average dental arch form of our sample at canine and molar level (mean±1SD) and would be suitable for cases where the treatment plan involves no expansion. In addition, 3 archwires have a shape that is slightly wider than the average arch form in the sample and could be used for cases in which the treatment plan includes no extractions but simply a slight expansion.

Development of a standardized testing system for orthodontic sliding mechanics.

BACKGROUND: The primary objective of this study was to develop a computer-controlled three-dimensional friction measuring system, the orthodontic friction simulator (OFS). A clinically-based in vitro experiment considering wet and dry friction for conventionally and self-ligated brackets is presented to elucidate debate surrounding sliding mechanics and illustrate capabilities of the OFS. METHODS: The OFS was designed and manufactured using sound engineering principles and with the primary concern of being able to measure all forces and moments generated during sliding mechanics. This required the implementation of a six-axis load cell. A variety of translation and rotation stages were also incorporated to allow for precise positioning of the bracket relative to the archwire. Once designed and built, the OFS was then used to compare conventional and self-ligation methods in both the wet and dry state. Damon Q brackets and 0.018″ × 0.025″ stainless steel wires were used for all tests with a sample size of n = 65 for each ligation method. Archwires were pulled at a speed of 0.1 mm/s in 11 increments of 0.1 mm. At each increment, the bracket would be rotated 0.5° resulting in a total archwire travel of 1.1 mm and a second-order bracket angle range of 0°-5°. A repeated measures ANOVA was conducted to determine if ligation method and/or addition of moisture effected resulting orthodontic loads. RESULTS: The developed equipment for studying orthodontic sliding mechanics was able to measure forces and moments in all three directions; a capability not previously realized in the literature. Additionally, it was found that passive ligation significantly reduced resistance to sliding, P ≤ 0.05, while the dry/wet state did not. CONCLUSIONS: The OFS certainly proved to be an adequate instrument for the scientific evaluation of orthodontic sliding mechanics. It is capable of measuring loads generated in all directions and is a fully automated apparatus allowing for simple and repeatable friction tests to be conducted. Furthermore, the addition of saliva was not found to significantly influence the loads generated during sliding mechanics regardless of ligation method.

Analysis of mesiodistal angulations of preadjusted brackets.

Manufacturers offer various prescriptions of preadjusted brackets for use in the "straight-wire" orthodontic technique. However, the need to incorporate bends in the rectangular wires during orthodontic finishing has led to concerns regarding the type of prescription chosen and the credibility of information provided by the manufacturer. The aim of this study was to compare the slot angulations of Roth prescription preadjusted metallic brackets for the maxillary left central incisor and maxillary left canine. For each tooth type, 10 brackets of three commercial brands (GAC, Forestadent and Morelli) were selected. Two individual metal matrices for brackets and tooth positioning were made for each group of teeth. Captured images were obtained by standardized ortho-radial photography with a digital camera. Images were exported and analyzed with the Image J software package. One-way ANOVA and Tukey statistical analyses were performed at the 5% significance level. For brackets of the maxillary left central incisor, differences in mean angulation were observed between the Morelli and GAC groups (p < 0.01) and between the Forestadent and GAC groups (p < 0.01). For brackets of the maxillary left canine, differences in mean angulation were found between the Morelli and GAC groups (p < 0.01) and between the Morelli and Forestadent groups (p < 0.05). In conclusion, despite their same prescription name, the different brands exhibited significantly different angulation measurements.

No reliable evidence to guide initial arch wire choice for fixed appliance therapy.

DATA SOURCES: The Cochrane Oral Health Group's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Medline and Embase databases were searched. Conference proceedings and abstracts from the British Orthodontic Conference European Orthodontic Conference and the International Association for Dental Research were also searched together with the reference lists of identified studies. Study authors were contacted for additional information. STUDY SELECTION: Randomised controlled trials of initial arch wire involving participants with upper and/or lower full arch fixed orthodontic appliances were included. DATA EXTRACTION AND SYNTHESIS: Study selection, data extraction and risk of bias assessment were carried out independently by at least two reviewers. RESULTS: Nine RCTs with 571 participants were included in this review. All trials were at high risk of bias. All trials had at least one potentially confounding factor (such as bracket type, slot size, ligation method, extraction of teeth) which is likely to have influenced the outcome and was not controlled in the trial. None of the trials reported the important adverse outcome of root resorption. The comparisons were made between:Multistrand stainless steel initial arch wires compared to superelastic nickel titanium (NiTi) initial arch wires. There were four trials in this group, with different comparisons and outcomes reported at different times. No meta-analysis was possible. There is insufficient evidence from these trials to determine whether or not there is a difference in either rate of alignment or pain between stainless steel and NiTi initial arch wires.Conventional (stabilised) NiTi initial arch wires compared to superelastic NiTi initial arch wires. There were two trials in this group, one reporting the outcome of alignment over six months and the other reporting pain over one week. There is insufficient evidence from these trials to determine whether or not there is any difference between conventional (stabilised) and superelastic NiTi initial arch wires with regard to either alignment or pain.Single-strand superelastic NiTi initial arch wires compared to other NiTi (coaxial, copper NiTi (CuNiTi) or thermoelastic) initial arch wires. The three trials in this comparison each compared a different product against single-strand superelastic NiTi. There is very weak unreliable evidence, based on one very small study (n = 24) at high risk of bias, that coaxial superelastic NiTi may produce greater tooth movement over 12 weeks, but no information on associated pain or root resorption. This result should be interpreted with caution until further research evidence is available. There is insufficient evidence to determine whether or not there is a difference between either thermoelastic or CuNiTi and superelastic NiTi initial arch wires. CONCLUSIONS: There is no reliable evidence from the trials included in this review that any specific initial arch wire material is better or worse than another with regard to speed of alignment or pain. There is no evidence at all about the effect of initial arch wire materials on the important adverse effect of root resorption. Further well-designed and conducted, adequately-powered RCTs are required to determine whether the performance of initial arch wire materials as demonstrated in the laboratory, makes a clinically important difference to the alignment of teeth in the initial stage of orthodontic treatment in patients.

Initial arch wires for tooth alignment during orthodontic treatment with fixed appliances.

BACKGROUND: Initial arch wires are the first arch wires to be inserted into the fixed appliance at the beginning of orthodontic treatment and are used mainly for the alignment of teeth by correcting crowding and rotations. With a number of different types of orthodontic arch wires available for initial tooth alignment, it is important to understand which wire is most efficient, as well as which wires cause the least amount of root resorption and pain during the initial aligning stage of treatment. This is an update of the review 'Initial arch wires for alignment of crooked teeth with fixed orthodontic braces' first published in the Cochrane Database of Systematic Reviews 2010, Issue 4. OBJECTIVES: To assess the effects of initial arch wires for alignment of teeth with fixed orthodontic braces in relation to alignment speed, root resorption and pain intensity. SEARCH METHODS: We searched the following electronic databases: the Cochrane Oral Health Group's Trials Register (to 2 August 2012), CENTRAL (The Cochrane Library 2012, Issue 7), MEDLINE via OVID (1950 to 2 August 2012) and EMBASE via OVID (1980 to 2 August 2012). We also searched the reference lists of relevant articles. There was no restriction with regard to publication status or language of publication. We contacted all authors of included studies to identify additional studies. SELECTION CRITERIA: We included randomised controlled trials (RCTs) of initial arch wires to align teeth with fixed orthodontic braces. Only studies involving participants with upper and/or lower full arch fixed orthodontic appliances were included. DATA COLLECTION AND ANALYSIS: Two review authors were responsible for study selection, validity assessment and data extraction. All disagreements were resolved by discussion amongst the review team. Corresponding authors of included studies were contacted to obtain missing information. MAIN RESULTS: Nine RCTs with 571 participants were included in this review. All trials were at high risk of bias and a number of methodological limitations were identified. All trials had at least one potentially confounding factor (such as bracket type, slot size, ligation method, extraction of teeth) which is likely to have influenced the outcome and was not controlled in the trial. None of the trials reported the important adverse outcome of root resorption.Three groups of comparisons were made.(1) Multistrand stainless steel initial arch wires compared to superelastic nickel titanium (NiTi) initial arch wires. There were four trials in this group, with different comparisons and outcomes reported at different times. No meta-analysis was possible. There is insufficient evidence from these trials to determine whether or not there is a difference in either rate of alignment or pain between stainless steel and NiTi initial arch wires.(2) Conventional (stabilised) NiTi initial arch wires compared to superelastic NiTi initial arch wires. There were two trials in this group, one reporting the outcome of alignment over 6 months and the other reporting pain over 1 week. There is insufficient evidence from these trials to determine whether or not there is any difference between conventional (stabilised) and superelastic NiTi initial arch wires with regard to either alignment or pain.(3) Single-strand superelastic NiTi initial arch wires compared to other NiTi (coaxial, copper NiTi (CuNiTi) or thermoelastic) initial arch wires. The three trials in this comparison each compared a different product against single-strand superelastic NiTi. There is very weak unreliable evidence, based on one very small study (n = 24) at high risk of bias, that coaxial superelastic NiTi may produce greater tooth movement over 12 weeks, but no information on associated pain or root resorption. This result should be interpreted with caution until further research evidence is available. There is insufficient evidence to determine whether or not there is a difference between either thermoelastic or CuNiTi and superelastic NiTi initial arch wires. AUTHORS' CONCLUSIONS: There is no reliable evidence from the trials included in this review that any specific initial arch wire material is better or worse than another with regard to speed of alignment or pain. There is no evidence at all about the effect of initial arch wire materials on the important adverse effect of root resorption. Further well-designed and conducted, adequately-powered, RCTs are required to determine whether the performance of initial arch wire materials as demonstrated in the laboratory, makes a clinically important difference to the alignment of teeth in the initial stage of orthodontic treatment in patients.

Initial arch wires for alignment of crooked teeth with fixed orthodontic braces.

BACKGROUND: The initial arch wire is the first arch wire to be inserted into the fixed appliance at the beginning of orthodontic treatment and is used mainly for correcting crowding and rotations of teeth. With a number of orthodontic arch wires available for initial tooth alignment, it is important to understand which wire is most efficient, as well as which wires cause the least amount of root resorption and pain during the initial aligning stage of treatment. OBJECTIVES: To identify and assess the evidence for the effects of initial arch wires for alignment of teeth with fixed orthodontic braces in relation to alignment speed, root resorption and pain intensity. SEARCH STRATEGY: We searched the following electronic databases: the Cochrane Oral Health Group's Trials Register (30th November 2009), CENTRAL (The Cochrane Library 2009, Issue 4), MEDLINE (1950 to 30th November 2009) and EMBASE (1980 to 30th November 2009). Reference lists of articles were also searched. There was no restriction with regard to publication status or language of publication. We contacted all authors of included studies to identify additional studies. SELECTION CRITERIA: Randomised controlled trials (RCTs) of initial arch wires to align crooked teeth with fixed orthodontic braces were selected. Only studies involving patients with upper and/or lower full arch fixed orthodontic appliances were included. DATA COLLECTION AND ANALYSIS: Two review authors were responsible for study selection, validity assessment and data extraction. All disagreements were resolved by discussion amongst the review team. Corresponding authors of included studies were contacted to obtain missing information. MAIN RESULTS: Seven RCTs, with 517 participants, provided data for this review. Among them, five trials investigated the speed of initial tooth alignment comparing: 0.016 inch ion-implanted A-NiTi wire versus 0.016 inch A-NiTi versus 0.0175 multistrand stainless steel wire; 0.016x0.022 inch medium force active M-NiTi wire versus 0.016x0.022 inch graded force active M-NiTi wire versus 0.0155 inch multistrand stainless steel wire; 0.016 inch superelastic NiTi wire versus 0.016 inch NiTi wire; 0.014 inch superelastic NiTi wire versus 0.0155 inch multistrand stainless steel wire; 0.016 inch CuNiTi wire versus 0.016 inch NiTi wire. The other two studies investigated pain intensity experienced by patients during the initial stage of treatment comparing: 0.014 inch superelastic NiTi wire versus 0.014 inch NiTi wire; 0.014 inch superelastic NiTi wire versus 0.015 inch multistrand stainless steel wire. Data analyses were often inappropriate within the included studies. AUTHORS' CONCLUSIONS: There is some evidence to suggest that there is no difference between the speed of tooth alignment or pain experienced by patients when using one initial aligning arch wire over another. However, in view of the general poor quality of the including trials, these results should be viewed with caution. Further RCTs are required.

[Comparison of mechanical properties on different phase transformation points of nickel-titanium orthodontic wires].

OBJECTIVE: To compare the mechanical properties of different phase transformation of nickel-titanium orthodontic archwires. METHODS: Nickel-titanium orthodontic archwires with same-sized (0.016") but different phase transformation were examined using a three-point bend test. Samples were tested at same conditions and oral temperature(37 degree), but in different utmost strain capacity, then the strain-stress chart was obtained, the phase transformation point (Af) was also examined. RESULT: The wires of the highest phase transformation point had the least orthodontic force; on the contrast the least phase transformation point had the highest orthodontic force at 3.0 mm utmost strain capacity. The orthodontic forces were not different at the little strain capacity (P >0.05), but which was significantly different adove the 0.5 mm (P<0.05), which was same as 3.0 mm. CONCLUSION: The nickel-titanium orthodontic archwires with high level of phase transformation have low orthodontic forces and more stability.

Forces in stainless steel, TiMolium and TMA intrusion arches, with different bending magnitudes.

The present study compared forces in stainless steel, TiMolium and TMA, V-bend intrusion arches with different magnitudes of flexion. The sample consisted of rectangular-section wires, caliber .017" x .025", with ten arches of each alloy. All V-bends were made 48 mm from the midline, using the same phantom upper jaw, maintaining the same distance between the tubes fixed to the molars and the midline. Loads necessary to deflect the arches by 5, 10, 15 and 20 mm were measured by means of an Instron dynamometer with a 1 kgf load cell. Calculations for sample size confirmed the suitability of using 10 arches of each alloy. Variance tests (ANOVA) of one factor and three levels, complemented by the Tukey test for multiple comparisons, identified that TMA(R) intrusion arches required a smaller quantity of load in relation to conventional steel and TiMolium at all levels of flexion. Furthermore, TiMolium presented intermediary characteristics between steel and TMA, and in all alloys increase in distance entailed a significant increase in force between all registered values, and that the increase in load necessary to deflect the arches at the intervals tended to decrease from first to last interval, these differences being more significant in steel, less in TiMolium and practically non-existent in TMA.

An in vitro comparison of the force decay generated by different commercially available elastomeric chains and NiTi closed coil springs.

This in vitro study was designed to compare the forces generated by commercially available elastomeric chains and NiTi closed coil springs, and to determine their force decay pattern. Forty elastomeric chains and forty NiTi closed coil springs were divided into 4 groups according to the following manufacturers: (1) Morelli, (2) Abzil, (3) TP Orthodontics and (4) American Orthodontics. The specimens were extended to twice their original length and stored in artificial saliva at 37 degrees C. Initial force was measured by means of an Instron universal testing machine and then at 1, 4, 7, 14, 21, and 28 days. The results revealed that the elastomeric chains delivered a mean initial force of 347 g for Morelli, 351 g for American Orthodontics, 402 g for Abzil, and 404 g for TP Orthodontics. The NiTi closed coil springs generated a mean initial force of 196 g for American Orthodontics, 208 g for TP Orthodontics, 216 g for Abzil, and 223 g for Morelli. The mean percentage of force decay observed after 28 days for the elastomeric chains was 37.4% for TP Orthodontics(R), 48.1% for American Orthodontics, 65.4% for Morelli, and 71.6% for Abzil. After 28 days, the NiTi closed coil springs presented a mean percentage of force decay of 22.6% for American Orthodontics, 29.8% for Abzil, 30.6% for Morelli, and 45.8% for TP Orthodontics. At the end of the study, significant differences were observed between the elastomeric chains and the NiTi closed coil springs. The results indicated that the studied NiTi closed coil springs are more adequate for dental movement than the elastomeric chains.

An in vitro comparison of the force decay generated by different commercially available elastomeric chains and NiTi closed coil springs

This in vitro study was designed to compare the forces generated by commercially available elastomeric chains and NiTi closed coil springs, and to determine their force decay pattern. Forty elastomeric chains and forty NiTi closed coil springs were divided into 4 groups according to the following manufacturers: (1) Morelli®, (2) Abzil®, (3) TP Orthodontics® and (4) American Orthodontics®. The specimens were extended to twice their original length and stored in artificial saliva at 37°C. Initial force was measured by means of an Instron universal testing machine and then at 1, 4, 7, 14, 21, and 28 days. The results revealed that the elastomeric chains delivered a mean initial force of 347 g for Morelli®, 351 g for American Orthodontics®, 402 g for Abzil®, and 404 g for TP Orthodontics®. The NiTi closed coil springs generated a mean initial force of 196 g for American Orthodontics®, 208 g for TP Orthodontics®, 216 g for Abzil®, and 223 g for Morelli®. The mean percentage of force decay observed after 28 days for the elastomeric chains was 37.4 percent for TP Orthodontics®, 48.1 percent for American Orthodontics®, 65.4 percent for Morelli®, and 71.6 percent for Abzil®. After 28 days, the NiTi closed coil springs presented a mean percentage of force decay of 22.6 percent for American Orthodontics®, 29.8 percent for Abzil®, 30.6 percent for Morelli®, and 45.8 percent for TP Orthodontics®. At the end of the study, significant differences were observed between the elastomeric chains and the NiTi closed coil springs. The results indicated that the studied NiTi closed coil springs are more adequate for dental movement than the elastomeric chains.

Este estudo in vitro foi delineado para comparar a força gerada por cadeias elastoméricas e por molas fechadas de NiTi comercialmente disponíveis e para determinar seu padrão de degradação de forças. Para tal, 40 segmentos de cadeia elastomérica e 40 molas fechadas de NiTi foram divididas em 4 grupos de acordo com a marca comercial: (1) Morelli®, (2) Abzil®, (3) TP Orthodontics® e (4) American Orthodontics®. As amostras foram distendidas ao dobro de seu comprimento original e imersas em solução de saliva artificial a 37°C. Uma máquina de ensaio (Instron) foi utilizada para aferir a força inicial e em 1, 4, 7, 14, 21 e 28 dias. Os resultados mostraram que as cadeias elastoméricas liberaram uma força média inicial de 404 g para a marca TP Orthodontics®, 402 g para Abzil®, 351 g para American Orthodontics® e 347 g para Morelli®. As molas fechadas de NiTi geraram uma força média inicial de 223 g para a marca Morelli®, 216 g para Abzil®, 208 g para TP Orthodontics® e 196 g para American Orthodontics®. A percentagem média de degradação da força após 28 dias para as cadeias elastoméricas foi de 37,4 por cento para TP Orthodontics®, 48,1 por cento para American Orthodontics®, 65,4 por cento para Morelli® e 71,6 por cento para Abzil®. A percentagem média de degradação da força após 28 dias para as molas fechadas de NiTi foi de 22,6 por cento para American Orthodontics®, 29,8 por cento para Abzil®, 30,6 por cento para Morelli® e 45,8 por cento para TP Orthodontics®. Ao final do experimento, observaram-se diferenças significantes entre as cadeias elastoméricas e as molas fechadas de NiTi. Os resultados permitem recomendar as molas fechadas de NiTi estudadas como dispositivos mais adequados para movimentação dentária do que as cadeias elastoméricas.

The release of nickel from orthodontic NiTi wires is increased by dynamic mechanical loading but not constrained by surface nitridation.

The influence of dynamic mechanical loading and of surface nitridation on the nickel release from superelastic nickel-titanium orthodontic wires was investigated under ultrapure conditions. Commercially available superelastic NiTi arch wires (size 0.018 x 0.025'') without surface modification (Neo Sentalloy) and with nitrogen ion implantation surface treatment (Neo Sentalloy Ionguard) were analyzed. Mechanical loading of wire segments with a force similar to the physiological situation was performed with a frequency of 5 Hz in ultrapure water and saline solution, respectively. The release of nickel was monitored by atomic absorption spectroscopy for up to 36 days. The mechanically loaded wires released significantly more nickel ( approximately 45 ng cm(-2) d(-1)) than did nonloaded wires (<1 ng cm(-2) d(-1)). There was no statistically significant effect of the testing solution (water or NaCl) or of the surface nitridation. The total amount of released nickel was small in all cases, but may nevertheless account for the occasional clinical observations of adverse reactions during application of NiTi-based orthodontic appliances. The surface nitridation did not constrain the release of nickel from NiTi under continuous mechanical stress.

Forces in stainless steel, TiMolium® and TMA® intrusion arches, with different bending magnitudes

The present study compared forces in stainless steel, TiMolium® and TMA®, V-bend intrusion arches with different magnitudes of flexion. The sample consisted of rectangular-section wires, caliber .017" x .025", with ten arches of each alloy. All V-bends were made 48 mm from the midline, using the same phantom upper jaw, maintaining the same distance between the tubes fixed to the molars and the midline. Loads necessary to deflect the arches by 5, 10, 15 and 20 mm were measured by means of an Instron dynamometer with a 1 kgf load cell. Calculations for sample size confirmed the suitability of using 10 arches of each alloy. Variance tests (ANOVA) of one factor and three levels, complemented by the Tukey test for multiple comparisons, identified that TMA® intrusion arches required a smaller quantity of load in relation to conventional steel and TiMolium® at all levels of flexion. Furthermore, TiMolium® presented intermediary characteristics between steel and TMA®, and in all alloys increase in distance entailed a significant increase in force between all registered values, and that the increase in load necessary to deflect the arches at the intervals tended to decrease from first to last interval, these differences being more significant in steel, less in TiMolium® and practically non-existent in TMA®.

O presente estudo comparou as forças em arcos de intrusão com dobra V confeccionados em aço inoxidável, TiMolium® e TMA®, com diferentes magnitudes de deflexão. A amostra constou de fios de secção retangular e calibre 0,017" x 0,025", com dez arcos de cada liga. Todas as dobras em V foram confeccionadas a 48 mm distantes da linha média, e foi utilizado o mesmo manequim de maxila para manter a mesma distância entre os tubos fixados nos molares e a linha média. As cargas necessárias para defletir os arcos em 5, 10, 15 e 20 mm foram mensuradas por meio de dinamômetro com célula de carga de 1 kgf, da marca Instron. O cálculo para o tamanho de amostra confirmou a possibilidade de se utilizar dez arcos de cada liga. Os testes de variância (ANOVA) de um fator e três níveis, complementados com os testes de Tukey para comparações múltiplas, identificaram que os arcos de intrusão de TMA® requereram menor quantidade de carga em relação ao aço convencional e ao TiMolium® em todos os níveis de deflexão; que o TiMolium® apresentou características intermediárias entre o aço e o TMA®; que em todas as ligas o aumento das distâncias implicou em aumento significativo da força entre todos os valores registrados; e que os incrementos de carga necessários para defletir os arcos nos intervalos tenderam a decrescer do primeiro ao último intervalo, sendo essas diferenças mais significantes no aço, menores no TiMolium® e praticamente inexistentes no TMA®.

Frictional evaluations of dental typodont models using four self-ligating designs and a conventional design.

Abstract: After a previous study using typodonts and three standardized archwire (AW) sizes, the frictional evaluations of four self-ligating brackets were directed toward the optimal AW-bracket system. Four participating manufacturers suggested three AWs, which were a representation of the three stages of orthodontic treatment, to be coupled with their respective self-ligating design. Four replicated typodont models were mounted with a self-ligating design, and a fifth model was mounted with a conventional design that served as a control. The first experiment evaluated the manufacturer-suggested AWs against the respective self-ligating design. Because no third-stage AWs could engage their respective designs, a second experiment was implemented to gain more detailed analyses of the designs. This experiment included any successful manufacturer-suggested AWs from the first experiment against the four self-ligating designs and the control design. All self-ligating designs performed with the efficiency and reproducibility associated with expectations. Specifically, self-ligation outperformed the conventional brackets when coupled with up to 0.020- x 0.020-inch wires. The clearance of the various AW sizes and alloys changed with malocclusion. Furthermore, the parameter that best correlated with drawing forces was the bending stiffness of the AW, which was directly associated with the nominal dimension of each wire. The best AW-bracket system can be selected, when taking into account the stiffness (elastic modulus and size of the AW) along with the amount of malocclusion present, once the treatment plan is determined.

Weld characteristics of orthodontic archwire materials.

Welding attachments to archwires can produce change in their physical as well as mechanical properties. This study evaluated three archwire alloy materials-stainless steel, Beta titanium, and Timolium for their weld characteristics. The study was divided into tensile-shear test using instron universal testing machine, surface evaluation with the help of scanning electron microscope, and metallographic examination with optical microscope. Six specimens were used for evaluation of each parameter. Increased strength in tensile-shear test and smooth surface and characteristic nugget formation in scanning and optical micrographs, respectively, clearly indicated superior weld characteristics for Beta titanium alloys when compared with the other two archwire alloys. Stainless steel was found to be intermediate in nature, whereas Timolium exhibited poor weld characteristics.

Static-dynamic friction transition of FRP esthetic orthodontic wires on various brackets by suspension-type friction test.

A new testing apparatus for the measurement of frictional properties was designed and the frictional coefficients were obtained and compared with each other in various combinations of brackets and orthodontic wires, including esthetic fiber-reinforced plastic (FRP) wire that was especially designed and manufactured. Three kinds of wires (stainless steel, nickel-titanium, and FRP) and four brackets (single-crystal alumina, polycrystalline alumina, polycarbonate, and stainless steel) were used. The testing was done under dry and wet conditions. The friction testing equipment was designed to attach the bracket to a C-shaped bar suspended with a variable mass, and sliding along a fixed wire. The transition between static and dynamic friction was measured as a breakaway force, with the use of a universal test machine. In addition to material properties, this testing fixture eliminates geometrical factors, such as the rotational moment at the edge of the bracket slot, deflection of the orthodontic wire, and tension of the ligature wire. Nearly ideal frictional properties between materials are obtained. The frictional properties of FRP wire were similar to those of metal wires on all brackets, except the polycrystalline alumina bracket. The frictional coefficient between the polycrystalline ceramic bracket and FRP wire was larger than that of other combinations. There was little difference in frictional coefficients between dry and wet conditions.

Transformation behavior, chemical composition, surface topography and bending properties of five selected 0.016" x 0.022" NiTi archwires.

PURPOSE: The aim of this study was to characterize five selected commercial NiTi archwires in terms of their transformation behavior, chemical composition, surface topography and mechanical properties (at temperatures of 22 degrees C, 37 degrees C and 60 degrees C). MATERIAL AND METHODS: The rectangular orthodontic archwires investigated were Neo Sentalloy F80 (GAC, Central Islip, NY, USA), 35 degrees C Thermo-Active Copper NiTi (A-Company/Ormco, Glendora, CA, USA), Rematitan "Lite" (Dentaurum, Pforzheim, Germany), Titanol SE S (Forestadent, Pforzheim, Germany) and Titanal (Lancer, San Marcos, CA, USA) in size 0.016" x 0.022". The chemical composition and surface topography were analyzed by energy dispersive X-ray spectroscopy using an analytical scanning electron microscope (XL30, EDAX SUTW Saphire Detector; Philips, Eindhoven, Netherlands). The transition temperatures were measured by means of differential scanning calorimetry (DSC; Perkin-Elmer Pyris 1, Perkin-Elmer, Fremont, CA, USA) in a range of - 80 degrees C to + 80 degrees C. The mechanical properties and their dependence on temperature were determined by means of 3-point bending tests. The binary archwire materials were characterized by a two-phase structure (NiTi matrix and Ni3Ti4 precipitates). RESULTS: The SEM analyses revealed abradant residues in virtually all archwires, while DSC revealed complex transformation properties. In addition to the martensitic and austenitic transformations, an R-phase transformation was also detected. The bending tests showed pronounced loading and unloading plateaus. The martensitic archwires (Neo Sentalloy F80, 35 degrees C Thermo-Active Copper NiTi) were found to have a lower strength than the martensitic-austenitic (Rematitan "Lite") and the austenitic archwires (Titanol SE S, Titanal). With increasing temperature (in the range from 22 degrees C to 60 degrees C) a linear rise in the plateau forces was recorded. CONCLUSIONS: When assessing the quality of archwires, account should be taken of the surface quality, as it is this that determines corrosion resistance, biocompatibility and friction characteristics. The mechanical properties depend on the initial state; moderate plateau forces and plateau moments can only be achieved with martensitic archwires. In contrast to conventional steel alloys, the strength characteristics are heavily dependent on temperature and need to be known if NiTi archwires are to be used to optimal effect. In addition, the superelastic plateau is used only partially, if at all, when minimum leveling is required.