Estudo Laboratorial Do Comportamento Mecânico De Duas Molas

• Autor(a) principal: Saúl Matos Castro
• Data de Publicação: 2008
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: https://hdl.handle.net/10216/56678
• topic: Outras ciências médicas; Other medical sciences

The possibility to quantify, as well as to control M/F ratios in the brackets are the key for a controlled and predictable dental movement. The present work has the purpose of determining the force systems in α (horizontal force, M/F ratios, C/D ratios) of the T and L shaped loops for the same vertical dimension (7mm), as well as for the same inter-bracket distance (13 mm). With five different pre-activation bends and two metallic alloys (stainless steel and titanium-molibdenum alloy - TMA) with a section of 0,017"x 0,025" Two hundred loops were submitted to the mechanical essay - for each pre-activation ten loops were used (5), metallic alloy (2) and geometry (2). The moment and horizontal force intensities were quantified using the OrthoMeasure Moment apparatus, the testing table and a digital comparator. The values were registered every 0,5 mm of activation, with an initial activation of 1 mm and a final activation of 6 mm. The data was statistically analysed using the ANOVA methodology for a significance level of 5%. The results allowed us to conclude that there are statistically significant average differences according to the pre-activation in all kinds of loops (TMA L, and T, steel L and T) at strength and ratio M/F levels. As to what concerns force, L loops registered higher values than T loops and the influence from pre-activation of force localization was confirmed. As to what concerns M/F ratios, T loops registered higher values than L loops. In the absence of pre-activations, the TMA loops presented higher values than steel loops, the maximum registered level being inferior to the vertical dimension of the loop. In the loops without pre-activation, an augmentation on the M/F ratio was demonstrated through an activation augmentation, an opposite was assessed in pre-activated loops. In most of the activations with pre-activated loops, the steel presented M/F ratio values higher than TMA. The increase in M/F ratio, assessed with the insertion of pre-activation bends, was higher when the bend distribution was partial or completely gingival. The loop presenting the best compromise between force and M/F ratio was the T loop in TMA, with a pre-activation of 40º, in the 1 mm to 4 mm activation interval.