Nano propriedades e composição do recobrimento, citotoxicidade e corrosão dos fios ortodônticos estéticos / Nano properties and coating composition, cytotoxicity and corrosion of aesthetic orthodontic wires

Este trabalho teve como objetivos avaliar a composição, as propriedades nanomecânicas e a resistência ao risco do recobrimento, a citotoxicidade e a liberação de metais de quatro marcas de fios ortodônticos com recobrimento estético como recebidos e após 21 dias de uso clínico. O estudo foi composto por dois experimentos. No primeiro, fios estéticos (Grupo OO: Ortho Organizers; Grupo TP: TP Orthodontics; Grupo OM: Orthometric; e Group TN: Trianeiro) foram avaliados quanto: à composição do recobrimento por espectroscopia no infravermelho por Transformada de Fourier; à dureza e ao módulo de elasticidade por testes de nano-indentação e quanto à resistência ao risco pelo teste de risco. No segundo experimento, os fios estéticos e seus respectivos fios convencionais de aço inoxidável e níquel titânio dos mesmos fabricantes foram avaliados quanto à citotoxicidade e à liberação de metais como recebidos e após 21 dias de exposição ao meio bucal. No ensaio de citotoxicidade cada tipo de fio foi incubado em placas contendo meio mínimo essencial de Eagle (MEM) e as alíquotas dos sobrenadantes de cada grupo foram retiradas em (T) 0 hora, 1, 2, 3, 7, 14, 21 e 60 dias e adicionadas a culturas de células L929 sendo a viabilidade celular determinada com o uso de vermelho neutro (Método Dye Uptake). O teste de corrosão foi realizando imergindo cada amostra numa solução de cloreto de sódio a 0,9% com 20µL de ácido nítrico por 28 dias. A quantidade de níquel, cromo, ferro, titânio, cobalto e manganês nos intervalos de tempo (T) 7, 14, 21, e 28 dias foi mensurada através de espectrômetro de emissão óptica com fonte de plasma indutivamente acoplado (ICP OES). Todos os recobrimentos foram caracterizados pelo pico de benzeno a cerca de 1500 cm-1 e são compostos de poliéster e politetrafluoretileno. O ensaio de risco mostrou uma alta elasticidade do recobrimento com recuperação elástica maior que 60%, mas com diferentes tipos de falhas e irregularidades ao longo da região do teste. Níquel foi o íon mais frequentemente liberado durante os intervalos do estudo. Depois do uso clínico, o grupo TP apresentou uma liberação significativa de níquel somente nos fios estéticos em T7, T14 e T21. No grupo TN, a liberação de níquel pós fase clínica também foi estatisticamente maior nestes fios em T7, T21 e T28. Os fios estéticos do grupo TP, após o uso clínico apresentaram uma menor viabilidade celular em comparação aos seus respectivos fios controles em T1, T3 e T28. Todos os grupos apresentaram uma superfície irregular do recobrimento com delaminações em várias áreas após 21 dias de exposição ao meio bucal. Mesmo os fios mais citotóxicos e que liberaram maiores quantidades de íons metálicos, apresentaram uma boa biocompatibilidade para o uso clínico. Sugere-se que o método de aplicação, a composição química do recobrimento, e o tratamento da superfície do substrato metálico influenciem na corrosão e na biocompatibilidade dos fios ortodônticos estéticos quando expostos ao meio bucal (AU)

The aims of this study were to evaluate the material composition, the nano mechanical properties and scratch resistance of the coating; the cytotoxicity and metal release of four brands of esthetic coated archwires as received and after 21 days of oral exposure. This study was composed by two experiments. In the first, esthetic archwires (Group OO: Ortho Organizers; Group TP: TP Orthodontics; Group OM: Orthometric; and Group TN: Trianeiro) were evaluated for composition assessed by infrared spectroscopy (FTIR). Coatings hardness and elastic modulus were analyzed by nanoindentation tests. Scratch resistance of coatings were evaluated by scratch test. In the second experiment, esthetic coated archwires and conventional stainless steel and nickel titanium archwires from the same manufacturers (control) were evaluated for cytotoxicity and metals released as received and after 21 days of oral exposure. The cytotoxicity assay was performed incubating each type of wire in Eagle's essential medium (MEM), removing the supernatant after T: 0 hour, 1, 2, 3, 7, 14, 21, 28 and 60 days and adding it to cultures of L929 mouse fibroblasts, and in each time the cell viability was determined with neutral red (dye uptake method). The corrosion testing was performed incubating each type of wire in a solution of 0,9% sodium chloride with 20µL of nitric acid for 28 days at 37 ±1 °C. The content of nickel, chromium, iron, titanium, cobalt and manganese ions at intervals of T: 7, 14, 21 and 28 days was measured by Inductively Coupled Plasma ­ Optical Emission Spectroscopy (ICPOES). All analyzed coatings were markedly characterized by the benzene peak at about 1500 cm-1 and are a composite of polyester and polytetrafluoroethylene. Scratch test showed a high coating elasticity after load removal with elastic recoveries greater than 60%, but different failure features could be observed along the scratches. Nickel was the most frequently ion released. After clinical use, TP group showed a significant nickel release only in esthetic wires at T7, T14 and T21. TN group presented a nickel release statistically higher in the retrieved esthetic wires at T7, T21 and T28. At T1, T3 and T28 the post clinical esthetic wires of TP group showed significant lower cell viability than their control wire. The esthetic coatings presented an irregular surface aspect and peeled off in many areas after oral exposure. Even the wires that were more cytotoxic and released more metals in sometimes, all seems to present a good biocompatibility for clinical use. However, the applying coating technique, the coating material and the metallic surface treatment in order to improve mechanical adhesion seem to influence the corrosion behavior and biocompatibility of esthetic orthodontic coated archwires when exposed to the oral environment (AU)

Infrared spectroscopy, nano-mechanical properties, and scratch resistance of esthetic orthodontic coated archwires.

OBJECTIVE: To evaluate the material composition, mechanical properties (hardness and elastic modulus), and scratch resistance of the coating of four commercialized esthetic orthodontic archwires. MATERIALS AND METHODS: The coating composition of esthetic archwires was assessed by Fourier-transform infrared spectroscopy (FTIR). Coating hardness and elastic modulus were analyzed with instrumented nano-indentation tests. Scratch resistance of coatings was evaluated by scratch test. Coating micromorphologic characteristics after scratch tests were observed in a scanning electron microscope. Statistical differences were investigated using analysis of variance and Tukey post hoc test. RESULTS: The FTIR results indicate that all analyzed coatings were markedly characterized by the benzene peak at about 1500 cm(-1). The coating hardness and elastic modulus average values ranged from 0.17 to 0.23 GPa and from 5.0 to 7.6 GPa, respectively. Scratch test showed a high coating elasticity after load removal with elastic recoveries >60%, but different failure features could be observed along the scratches. CONCLUSION: The coatings of esthetic archwires evaluated are probably a composite of polyester and polytetrafluoroethylene. Delamination, crack propagation, and debris generation could be observed along the coating scratches and could influence its durability in the oral environment.

Coating stability and surface characteristics of esthetic orthodontic coated archwires.

OBJECTIVE: To evaluate the coating thickness of four brands of as-received esthetic coated rectangular archwires and their surface characteristics and coating stability after 21 days of oral exposure compared to those of conventional stainless steel (SS) and nickel titanium (NiTi) ones. MATERIALS AND METHODS: The labial surface of the selected archwires was observed with a stereoscope and in a scanning electron microscope, and surface roughness was assessed with an atomic force microscope. The coating thickness of as-received wires and the percentage of coating lost on the labial surface of retrieved wires were measured using Image Pro Plus 4.5 software. RESULTS: All groups showed an average coating thickness of less than 0.002 inches. After oral exposure, archwires from two groups lost all coating on the labial surface. On average, 28.71% and 72.90% of the coating was lost in each of the other two groups, and the surface roughness of the remaining coating was higher than postclinical control wires. CONCLUSION: Coated archwires had a low esthetic value as they presented a nondurable coating. The remaining coating showed a severe deterioration and a greater surface roughness than postclinical control counterparts (conventional SS and NiTi wires).

Cross-section dimensions and mechanical properties of esthetic orthodontic coated archwires.

INTRODUCTION: There has been continuing interest in the development and use of esthetic and effective orthodontic archwires. The aims of this study were to evaluate the inner alloy core dimensions of 4 brands of as-received esthetic coated wires and their mechanical properties before and after 21 days of oral exposure, compared with conventional stainless steel and nickel titanium wires. METHODS: Four groups (Ortho Organizers, Carlsbad, Calif; TP Orthodontics, LaPorte, Ind; Orthometric, Beijing, China; and Trianeiro, Rio Claro, São Paulo, Brazil) of orthodontic archwires were tested. Five properties were evaluated: inner wire dimensions, modulus of elasticity, modulus of resilience, maximum deflection force, and load deflection curve characteristics. Images of the transverse sections from the specimens were made with a stereoscope. The inner alloy core dimensions of each wire were measured by using Image Pro Plus software (version 4.5; Media Cybernetics, Silver Spring, Md). All specimens were tested in a universal testing machine in a 3-point bending test. RESULTS: Coated wires of the Ortho Organizers and Trianeiro groups showed greater reductions in their inner alloy core dimensions and produced lower loading and unloading forces and lower modulus of elasticity, modulus of resilience, and maximum deflection force values than did their control wires. Inner alloy core dimensions and the mechanical behavior of coated wires practically did not differ from the control wires in the TP Orthodontics and Orthometric groups. CONCLUSIONS: The reduction on the inner alloy core dimensions to compensate for the coating thickness seems to be the variable responsible for greater changes in the mechanical properties of esthetic coated wires.

Color stability and fluorescence of different orthodontic esthetic archwires.

OBJECTIVE: To evaluate the color stability of six esthetic archwires at different time periods and their fluorescence. MATERIALS AND METHODS: Samples were evaluated after 7, 14, and 21 days of immersion in staining solution. Color measurements were performed by means of a spectrophotometer according to the Commission Internationale de I'Eclairage L*a*b* system, and color changes (ΔE*) and National Bureau of Standards units were computed. The fluorescence of as-received samples was evaluated by two observers and compared with that of a bovine central incisor. Statistical differences were investigated using analysis of variance and Tukey's post hoc test. RESULTS: All brands showed statistically significant color change after 21 days (ΔE* from 1.88 to 12.06). The Optis archwire (fiber-reinforced composite) presented the highest color alteration, although staining was observed only near its ends. The Trianeiro archwire (coated nickel-titanium) and the Ortho Organizers archwire (coated stainless steel) presented with less color change. The Optis archwire was the only one that presented with fluorescence similar to that of bovine teeth. CONCLUSIONS: All esthetic archwires assessed showed clinically noticeable color change after 21 days in staining solution. The optical properties of currently available esthetic archwires may not yet be ideal.

Relapse of a maxillary median diastema: closure and permanent retention.

The purpose of this article was to describe the closure of a maxillary median diastema of a 26-year-old woman that had been corrected before during orthodontic treatment but reopened after dental trauma in a car accident. A clear esthetic device made from a tray like those used for home bleaching was used, providing a comfortable, nearly undetectable, and efficient solution. A permanent fixed retainer was bonded again to the maxillary central incisors to prevent relapse.

Avaliação das tensões liberadas por elásticos ortodônticos em cadeia: estudo in vitro / Assessment of force decay in orthodontic elastomeric chains: an in vitro study

INTRODUÇÃO: os materiais elastoméricos são considerados importantes fontes de força para a movimentação ortodôntica. OBJETIVO: avaliar a liberação de tensões de quatro marcas comerciais de elásticos ortodônticos em cadeia (Morelli, Ormco, TP e Unitek), em função do tempo, quando mantidas tensionadas por uma força inicial de 150g e imersas em saliva artificial a 37ºC. MÉTODOS: os elásticos em cadeia foram tensionados entre pinos de aço, fixados em uma placa de resina acrílica à distância de 15mm (Morelli e TP) e de 16mm (Unitek e Ormco), ambas medidas correspondendo a uma força de 150g. A leitura da quantidade de tensão liberada pelos elásticos foi realizada com um dinamômetro nos intervalos 30 minutos, 7, 14 e 21 dias. Os dados obtidos foram submetidos à análise de variância (ANOVA) (p<0,05) e ao teste de Comparações Múltiplas de Tukey. RESULTADOS: após 30 minutos de teste, verificou-se redução entre 19 por cento e 26,67 por cento na quantidade de tensão liberada pelos elásticos; e entre 36,67 por cento e 57 por cento após 21 dias de estiramento constante. CONCLUSÕES: os elásticos em cadeia que apresentaram comportamento mais estável foram os da marca TP, pois relataram menor perda de potencial elástico nos intervalos de tempo testados. Os da marca Unitek demonstraram maior redução de tensão liberada. As marcas Ormco e Morelli obtiveram resultados semelhantes entre si.

INTRODUCTION: Elastomeric materials are considered important sources of orthodontic forces. OBJECTIVE: To assess force degradation over time of four commercially available orthodontic elastomeric chains (Morelli, Ormco, TP and Unitek). METHODS: The synthetic elastics were submerged in 37 ºC synthetic saliva and stretched by a force of 150 g (15 mm - Morelli and TP; 16mm - Unitek and Ormco). With a dynamometer, the delivered force was evaluated at different intervals: 30 minutes, 7 days, 14 days and 21 days. The results were subjected to ANOVA and Tukey's test. RESULTS: There was a force decay between 19 percent to 26.67 percent after 30 minutes, and 36.67 percent to 57 percent after 21 days of activation. CONCLUSIONS: TP elastomeric chains exhibited the smallest percentage of force decay, with greater stability at all time intervals tested. Meanwhile, the Unitek chains displayed the highest percentage of force degradation, and no statically significant difference was found in force decay between Ormco and Morelli elastomeric chains during the study period.

Análise de duas metodologias na aferição de infiltração por corante em apicoplastias com retro-obturações / Analysis of two different methods to measure dye infiltration in apicoplasties with retrograde root filling

Diferentes metodologias para verificar o sucesso de materiais odontológicos em apicoplastias com retro-obturaçãotêm sido utilizadas em estudos de infiltração marginal por corante. Apicoplastia é o aplainamento de umápice radicular sem a necessidade de sua amputação, com sua plástica correta. Objetivo: Esta pesquisa objetivou avaliar os resultados de infiltração da rodamina B a 1 por cento num grupo experimental, comparando-se a profundidadede penetração do corante com a sua área de impregnação nas mesmas amostras em apicoplastias comretro-obturação. Métodos: Para tanto utilizaram-se doze caninos humanos superiores tratados endodonticamentee retro-obturados com MTA. Na análise das amostras utilizou-se o software Image Tool® para realizar a morfometriacomputadorizada. Resultados: Os resultados demonstraram um desvio-padrão baixo (4,79) para a mensuração da área e alto (15,05) para mensuração da profundidade de penetração do corante. O teste Mann- Whitney demonstrou diferenças estatisticamente significativas entre os grupos, com p < 0,0001. Conclusão: A utilização da área impregnada por corante, em substituiçãoà profundidade de sua penetração, apresentouse como uma melhor alternativa para mensuração dos escores de infiltração marginal, considerando-se os parâmetros metodológicos utilizados nesta pesquisa

Force degradation in orthodontic elastic chains / Degradação de forças em correntes elásticas ortodônticas

Purpose: This in vitro study aimed to analyze the force degradation of four commercial brands of orthodontic elastics chain (Morelli, Ormco, TP, and Unitek) over 21 days. Methods: The elastics chains were stretched and maintained at a standardized distance equivalent to a force of 150 g. The amount of force generated by the elastics chains were measured by using a dynamometer (ZEUZAN 300 g) at intervals of 30 minutes, 7, 14, and 21 days. Data were analyzed by ANOVA and Tukey's test at the 5% level of significance. Results: There was a reduction of 5% to 15% in the amount of force generated by the elastic chains after 30 minutes and of 22% to 47% after 21 days of elastic activation. Conclusion: Unitek chains displayed the highest percentage of force degradation, while TP exhibited the smallest percentage of force degradation and showed the greatest stability at all intervals tested.

Objetivo: Este estudo teve por objetivo analisar a degradação da força gerada por quatro marcas comerciais de elásticos ortodônticos em cadeia (Morelli, Ormco, TP e Unitek) em função do tempo. Metodologia: Os elásticos foram mantidos continuamente estirados a uma distância equivalente à força de 150 g. A leitura da quantidade de força gerada pelas correntes elásticas foi mensurada utilizando-se um dinamômetro da marca ZEUZAN 300 g, nos intervalos: 30 minutos, 7, 14, 21 dias. Os resultados foram analisados por ANOVA e teste de Tukey ao nível de significância de 0,05. Resultados: Verificou-se uma redução na quantidade de força gerada pelos elásticos de 5% a 15% em 30 minutos de teste e de 22% a 47% em 21 dias de estiramento constante. Conclusão: A marca Unitek obteve um maior percentual de degradação de força, enquanto a marca TP um menor percentual de degradação de força mostrando comportamento mais estável em todos os intervalos de tempo testados.