Change in crown inclination accompanying initial tooth alignment with round archwires

ABSTRACT Objective: To evaluate, in-vitro, the change in crown inclination that occurs during orthodontic leveling and alignment using different archwire-bracket-ligation combinations. Materials and Methods: Four archwire types were tested: (1) 0.012-in stainless steel and (2) 0.0155-in stainless steel multi-stranded, (3) 0.012-in nitinol Orthonol® and (4) 0.012-in nitinol Thermalloy®. Combinations with five types of 0.022-in slot orthodontic brackets were tested: SmartClipTM and Time3® self-ligating brackets, Mini-Taurus® and Victory SeriesTM conventional brackets, and Synergy® conventional-low friction bracket. Conventional brackets were ligated with both stainless steel and elastomeric ligatures. The simulated malocclusion comprised 2.0mm gingival and 2.0mm labial displacements of a maxillary right central incisor. Rotation around the Y-axis (representing labio-palatal inclination) was measured for the different archwire-bracket-ligation combinations. Results: The largest rotation was measured whith Orthonol® and Thermalloy® wires when combined with SmartClipTM brackets (8.07±0.24º and 8.06±0.26º, respectively) and with Synergy® brackets ligated with stainless steel ligatures (8.03±0.49º and 8.0±0.37º, respectively). The lower rotation was recorded when Thermalloy®, multi-stranded, and Orthonol® wires were ligated with elastomeric rings to Mini-Taurus® brackets (1.53±0.18º, 1.65± 0.23º and 1.70±0.28º, respectively) and to Victory SeriesTM brackets (1.68± 0.78º, 2.92± 1.40º and 1.74±0.46º, respectively). Conclusions: All archwire-bracket-ligation combinations produced lingual crown inclination; however, lower changes were observed when the conventional brackets were ligated with elastomeric rings. The multi-stranded archwire produced less rotation with nearly every bracket-ligation combination, compared to the other archwires. The effect of the archwire-bracket-ligation combination on tooth inclination during leveling and alignment should be considered during planning treatment mechanics.

RESUMO Objetivo: Avaliar, in vitro, as mudanças na inclinação das coroas dentárias que acontecem durante o alinhamento e nivelamento usando diferentes combinações de arcos/braquetes/ligaduras. Material e Métodos: Foram usados quatro tipos de arcos ortodônticos: (1) 0,012" de aço inoxidável, (2) 0,0155" de aço multifilamentado, (3) Orthonol® 0,012" de nitinol e (4) Thermalloy® 0,012" de nitinol. Esses arcos foram combinados com cinco tipos de braquetes ortodônticos com slot 0,022": braquetes autoligáveis SmartClipTM e Time3®, braquetes convencionais Mini-Taurus® e Victory SeriesTM, e braquetes convencionais de baixo atrito Synergy®. Os braquetes convencionais receberam ligaduras de aço ou elastoméricas. A má oclusão simulada foi composta por um deslocamento do incisivo central superior direito em 2 mm para a cervical e 2 mm para a vestibular. A rotação ao redor do eixo Y (representando a inclinação vestibulolingual) foi medida para as diferentes combinações de arco/braquete/ligadura. Resultados: A maior rotação foi medida quando os arcos Orthonol® e Thermalloy® foram usados com os braquetes SmartClipTM (8,07±0,24º e 8,06±0,26º, respectivamente) e com os braquetes Synergy® com ligaduras metálicas (8,03±0,49º e 8,0±0,37º, respectivamente). A menor rotação foi vista quando os arcos Thermalloy®, multifilamentado e Orthonol® foram presos por ligaduras elastoméricas aos braquetes Mini-Taurus® (1,53±0,18º, 1,65±0,23º e 1,70±0,28º, respectivamente) e aos braquetes Victory SeriesTM (1,68±0,78º, 2,92±1,40º e 1,74±0,46º, respectivamente). Conclusões: todas as combinações arco-braquete-ligadura produziram inclinação palatina da coroa. Entretanto, as menores mudanças foram observadas quando os braquetes convencionais receberam ligaduras elastoméricas. O arco multifilamentado produziu menor rotação com quase todas as combinações braquete-ligadura, em comparação aos outros arcos. O efeito da combinação arco-braquete-ligadura na inclinação dentária durante o alinhamento e nivelamento deve ser considerado durante o planejamento da mecânica dos tratamentos.

Comparison of deflection forces of esthetic archwires combined with ceramic brackets

Abstract Coated archwires and ceramic brackets have been developed to improve facial esthetics during orthodontic treatment. However, their mechanical behavior has been shown to be different from metallic archwires and brackets. Therefore, the aim of this study was to compare the deflection forces in coated nickel-titanium (NiTi) and esthetic archwires combined with ceramic brackets. Material and Methods Non-coated NiTi (NC), rhodium coated NiTi (RC), teflon coated NiTi (TC), epoxy coated NiTi (EC), fiber-reinforced polymer (FRP), and the three different conventional brackets metal-insert polycrystalline ceramic (MI-PC), polycrystalline ceramic (PC) and monocrystalline ceramic (MC) were used. The specimens were set up on a clinical simulation device and evaluated in a Universal Testing Machine (Instron). An acrylic device, representative of the right maxillary central incisor was buccolingually activated and the unloading forces generated were recorded at 3, 2, 1 and 0.5 mm. The speed of the testing machine was 2 mm/min. ANOVA and Tukey tests were used to compare the different archwires and brackets. Results The brackets presented the following decreasing force ranking: monocrystalline, polycrystalline and polycrystalline metal-insert. The decreasing force ranking of the archwires was: rhodium coated NiTi (RC), non-coated NiTi (NC), teflon coated NiTi (TC), epoxy coated NiTi (EC) and fiber-reinforced polymer (FRP). At 3 mm of unloading the FRP archwire had a plastic deformation and produced an extremely low force in 2; 1 and 0.5 mm of unloading. Conclusion Combinations of the evaluated archwires and brackets will produce a force ranking proportional to the combination of their individual force rankings.

Effects of clinical use and sterilization on surface topography and surface roughness of three commonly used types of orthodontic archwires.

Aim: To evaluate the changes in surface topography and roughness of stainless steel (SS), nickel‑titanium and beta‑titanium (β‑Ti) archwires after clinical use and sterilization. Settings and Design: Thirty wires each of SS, nitinol, and β‑Ti (3M Unitek) were tested in as received, as received and autoclaved, and clinically retrieved then autoclaved conditions. Materials and Methods: A sterilization protocol of 134°C for 18 min was performed using an autoclave. Surface topography of specimens from each subgroup was examined using an environmental scanning electron microscope (ESEM model Quanta 200, The Netherlands) at ×100, ×1000, and ×2500 magnifications. Surface roughness was measured using arithmetic mean roughness (Ra) values obtained from optical profilometric scanning (Taylor Hobson, Leicester, UK). Statistical Analysis: Data were analyzed by one‑way analysis of variance and Tukey’s post‑hoc procedures. Results: Scanning electron microscope images revealed an increase in surface irregularities in SS and nitinol wires after clinical use. There was a significant increase in Ra values of SS orthodontic wires after intra‑oral exposure (P = 0.0002). Conclusion: Surface roughness of SS wires increased significantly after clinical use. Autoclave sterilization did not affect considerably on surface characteristics of any archwire.

Mechanical properties of NiTi and CuNiTi shape-memory wires used in orthodontic treatment. Part 1: stress-strain tests

OBJECTIVE: This research aimed to compare, through traction tests, eight types of superelastic and heat-activated NiTi archwires, by six trade companies (GAC, TP, Ormco, Masel, Morelli and Unitek) to those with addition of copper (CuNiTi 27ºC and 35ºC, Ormco). METHODS: The tests were performed in an EMIC mechanical testing machine, model DL10000, capacity of 10 tons, at the Military Institute of Engineering (IME). RESULTS: The results showed that, generally, heat-activated NiTi archwires presented slighter deactivation loadings in relation to superelastic. Among the archwires that presented deactivation loadings biologically more adequate are the heat-activated by GAC and by Unitek. Among the superelastic NiTi, the CuNiTi 27ºC by Ormco were the ones that presented slighter deactivation loadings, being statistically (ANOVA) similar, to the ones presented by the heat-activated NiTi archwires by Unitek. When compared the CuNiTi 27ºC and 35ºC archwires, it was observed that the 27ºC presented deactivation forces of, nearly, ⅓ of the presented by the 35ºC. CONCLUSION: It was concluded that the CuNiTi 35ºC archwires presented deactivation loadings biologically less favorable in relation to the other heat-activated NiTi archwires, associated to lower percentage of deformation, on the constant baselines of deactivation, showing less adequate mechanical behavior, under traction, in relation to the other archwires.

OBJETIVO: o objetivo dessa pesquisa foi comparar, por meio de ensaios de tração, oito tipos de fios de NiTi superelásticos e termoativados, de seis empresas comerciais (GAC, TP, Ormco, Masel, Morelli e Unitek) àqueles com adição de cobre (CuNiTi 27ºC e 35ºC, da ORMCO). MÉTODOS: os ensaios foram realizados em máquina de ensaios mecânicos, da marca EMIC, modelo DL10000, de 10 toneladas de capacidade, no Instituto Militar de Engenharia (IME). RESULTADOS: os resultados mostraram que, de forma geral, os fios de NiTi termoativados apresentaram cargas mais suaves de desativação que os superelásticos. Entre os fios que apresentaram as cargas de desativação biologicamente mais adequadas, estão os termoativados da GAC e da Unitek. Entre os fios de NiTi superelásticos, os de CuNiTi 27ºC da Ormco foram os que apresentaram as cargas mais suaves de desativação, sendo estatisticamente semelhantes (ANOVA) às apresentadas pelos fios de NiTi termoativados da Unitek. Quando comparados os fios de CuNiTi 27ºC aos de 35ºC, observou-se que os primeiros apresentaram forças de desativação de, aproximadamente, ⅓ das apresentadas pelos últimos. CONCLUSÃO: conclui-se que os fios de CuNiTi 35ºC apresentaram cargas de desativação biologicamente menos favoráveis em relação aos demais fios de NiTi termoativados, sendo associadas a percentuais inferiores de deformação, nos patamares constantes de desativação, demonstrando comportamento mecânico, sob tração, menos adequado em relação aos demais fios.

In vitro force delivery of nickel-titanium superelastic archwires in vertical displacement

OBJECTIVE: The purpose of this study was to evaluate the force delivered by different superlastic nickel-titanium wires during vertical displacement, in order to determine whether their stress release meets the criteria for constant and light forces that are usually accredited to these archwires. METHOD: Ten samples of 6 brands of 0.016-in archwires (Ormco, GAC, Morelli, TP, American Orthodontics e Rocky Mountain) were tested in a complete metal model using Dynalock brackets (3M Unitek™). In the canine position, there was a sliding bracket connected to a pole. This set was related to a load cell of 0.5 kg attached to a universal testing machine (Autograph AG-199kNG, Shimadzu). The crosshead speed was 0.5 mm/min and the maximum displacement was 1.0 mm. The model was submerged in temperature-controlled water. The results were analyzed by ANOVA (p < 0.05), using the software SAS System 8.02, Cry, NC, USA. RESULTS: The TP archwire had the lowest force throughout the test, although the final force was high (277.91 g). The Rocky Mountain archwire had the highest force release (455.41 g). CONCLUSION: The different brands of wires tested in this study failed in delivering low and constant forces as expected from superlastic nickel-titanium wires. The forces were extremely heavy for a vertical tooth movement.

OBJETIVO: o objetivo deste estudo foi avaliar a força liberada por diferentes fios de níquel-titânio (NiTi) superelástico em deslocamento vertical, a fim de determinar se a liberação de estresse por esses satisfaz o critério de forças suaves e constantes, geralmente atribuído a tais arcos. MÉTODOS: dez amostras de seis arcos de NiTi superelástico 0,016” de marcas comerciais diferentes (Ormco, GAC, Morelli, TP, American Orthodontics e Rocky Mountain) foram testados em um modelo metálico usando braquetes Dynalock (3M Unitek). Na região do canino, havia um braquete móvel conectado a uma haste, a qual estava relacionada com uma célula de carga de 0,5kg de uma máquina universal de ensaios (Autograph AG-199kNG, Shimadzu). O deslocamento do conjunto na região do canino foi realizado a uma velocidade constante de 0,5mm/min e o deslocamento máximo foi de 1,0mm. O conjunto foi submerso em água com temperatura controlada a 37ºC. RESULTADOS: os resultados obtidos foram avaliados por ANOVA (p <0,05), usando o software SAS System 8.02, Cry, NC, EUA. O arco da TP apresentou a menor força durante todo o teste, embora a força final tenha sido elevada (277,91g). O fio da Rocky Mountain demonstrou a maior liberação de força (455,41g). CONCLUSÕES: conclui-se que todas as diferentes marcas comerciais testadas nesse estudo falharam em liberar forças baixas e constantes, como é esperado nos fios de níquel-titânio superelástico. As forças foram extremamente pesadas para o movimento vertical de dentes.