Abstract
BackgroundTorsions in rectangular wires are the essential part of corrections in the finishing stage of treatment. Moreover the greatest amounts of torques are applied in the molar areas. a clinically effective moment is between 5 and 20 Nmm. In this study we have decided to evaluate the impact of different tube sizes and different dimensions of wires with different modulus of elasticities on the amount torsional bond strength of molar tubes.Material and Methods60 human impacted molar teeth were collected. A buccal tube was bonded on the buccal surface of all the samples by using light cured adhesive resin. After that, the teeth were mounted in a hard acrylic block. According to the size of buccal tube and the rectangular wires to be tested 4 groups will be designed. Torsional force was applied by instron machine. The torque angle at 5Nmm and at 20Nmm point will be calculated: which means, how many degrees of torque is required to reach the maximum 20Nmm moment from the minimum 5Nmm.One-way ANOVA was used to compare torque angle in all of the groups.ResultsThe least amount of clinically significant angle was 2.2 ᵒ in the 0.017×0.025 SS and the largest amount of it was 23.7 ᵒ in the 0.017×0.025 TMA in 0.018×0.025 slot molar tube. But, this angle was 19.9 ᵒand 13.6 ᵒ in 0.019×0.025 SS and 0.019×0.025 TMA archwire in 0.022×0.028 molar tube.ConclusionsThe 0.017×0.025 SS archwire in 0.018×0.025 molar tube had the lowest clinically significant angle. The largest amount was seen in group 0.017×0.025 TMA in 0.018×0.025 slot molar tube. Key words: Torsional efficacy, rectangular wires, buccal tubes, torque angle.
Highlights
To have a correct axial inclination at the final stages of fixed orthodontic treatment, a controlled root movement is required which is reffered to as third order movement
The least amount of clinically significant angle is shown in the combination 0.017×0.025inch SS archwire in 0.018×0.025-inch molar tube which was 2.2 o
In comparison between each two groups, this combination (0.017×0.025-inch SS archwire in 0.018×0.025-inch molar tube) was significantly lower than other groups. (P0/05)
Summary
To have a correct axial inclination at the final stages of fixed orthodontic treatment, a controlled root movement is required which is reffered to as third order movement. The couple force provides rotation of teeth in bucco-lingual direction is called torque. Torque can be observed from a mechanical or clinical point of view It is the rotation of structure around its long axis. This would be the any rotation perpendicular to the long axis [2]. Results: The least amount of clinically significant angle was 2.2 o in the 0.017×0.025 SS and the largest amount of it was 23.7 o in the 0.017×0.025 TMA in 0.018×0.025 slot molar tube. The largest amount was seen in group 0.017×0.025 TMA in 0.018×0.025 slot molar tube
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