A utilização de diferentes configurações de molas T para a obtenção de sistemas de forças otimizados
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Data
2006-10-01
Autores
Thiesen, Guilherme
Rego, Marcus Vinicius Neiva Nunes do
Menezes, Luciane Macedo de
Shimizu, Roberto Hideo [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Dental Press Editora
Resumo
OBJETIVO: determinar as características mecânicas de molas T e T com helicóides, quando da incorporação de variações na liga metálica (aço inoxidável e beta-titânio), na intensidade de dobras de pré-ativação (0º e 40º/180º) e na secção transversal do fio utilizado para a construção destas molas (0,017 x 0,025 e 0,019 x 0,025). METODOLOGIA: foram submetidas ao ensaio mecânico 80 molas para fechamento de espaços, sendo estas centralizadas em um espaço de 21mm. As magnitudes de força horizontal, proporção momento/força e relação carga/deflexão produzidas pelos corpos de prova foram quantificadas utilizando-se um transdutor de momentos acoplado ao módulo indicador digital para extensiometria e adaptado a uma máquina universal de ensaios Instron. As molas foram submetidas a uma ativação total de 5mm, sendo registrados os valores a cada 1mm de ativação. No tratamento estatístico dos dados obtidos, foi realizada a análise de variância, sendo esta complementada pelo teste de comparações múltiplas de Tukey, considerando o nível de significância de 5%. RESULTADOS E CONCLUSÕES: os resultados demonstraram que, de maneira geral, as molas T com helicóides produziram menores magnitudes de força horizontal e relação carga/deflexão do que as molas T. Na presença de pré-ativação, as molas produziram altas proporções momento/força, enquanto, na ausência de dobras de pré-ativação, as mesmas geraram baixas proporções momento/força. Dentre todas as variáveis analisadas, aquela que apresentou uma maior influência na força horizontal e na relação carga/deflexão produzidas pelas molas foi a liga metálica. Já a proporção momento/força mostrou ser influenciada em maior grau pela pré-ativação das molas de fechamento.
Resumo AIM: the present study determined the force systems produced by T-loop and T-loop with helices, with employment of different alloys (stainless steel and beta-titanium), different preactivation bends intensities (0º and 40º/180º) and different transverse sections (0.017 x 0.025 and 0.019 x 0.025). METHODS: 80 loops for space closure were submitted to mechanical testing, which were centralized in a space of 21mm. The magnitudes of horizontal force, moment/force ratio and load/deflection ratio were quantified using a moment transducer connected to a digital indicator for extensometry adapted to an Instron universal testing machine (model TTDML). The specimens were distended to a total activation of 5mm, being registered the values at every 1mm of activation. The data achieved were statistically analyzed by means of variance analysis and the Tukey test for multiple comparisons at a significance level of 5%. RESULTS and CONCLUSION: in general, the results indicated that the T-loops with helices produced lower magnitudes of horizontal force and load/deflection ratio than the T-loops. When inserted with the preactivation bends, the loops yielded high magnitudes of moment/force ratios, while when these preactivation bends were not presented, the moment/force ratios were low. The metallic alloy was the variable that presented the largest influence on the horizontal force and load/deflection ratio. The moment/force ratio was more intensely influenced by the incorporation of preactivation bends in the closure loops.
Resumo AIM: the present study determined the force systems produced by T-loop and T-loop with helices, with employment of different alloys (stainless steel and beta-titanium), different preactivation bends intensities (0º and 40º/180º) and different transverse sections (0.017 x 0.025 and 0.019 x 0.025). METHODS: 80 loops for space closure were submitted to mechanical testing, which were centralized in a space of 21mm. The magnitudes of horizontal force, moment/force ratio and load/deflection ratio were quantified using a moment transducer connected to a digital indicator for extensometry adapted to an Instron universal testing machine (model TTDML). The specimens were distended to a total activation of 5mm, being registered the values at every 1mm of activation. The data achieved were statistically analyzed by means of variance analysis and the Tukey test for multiple comparisons at a significance level of 5%. RESULTS and CONCLUSION: in general, the results indicated that the T-loops with helices produced lower magnitudes of horizontal force and load/deflection ratio than the T-loops. When inserted with the preactivation bends, the loops yielded high magnitudes of moment/force ratios, while when these preactivation bends were not presented, the moment/force ratios were low. The metallic alloy was the variable that presented the largest influence on the horizontal force and load/deflection ratio. The moment/force ratio was more intensely influenced by the incorporation of preactivation bends in the closure loops.
Descrição
Palavras-chave
Ortodontia, Biomecânica, Fechamento de espaço ortodôntico, Orthodontics, Biomechanics, Orthodontic space closure
Como citar
Revista Dental Press de Ortodontia e Ortopedia Facial. Dental Press Editora, v. 11, n. 5, p. 57-77, 2006.