Allahyar Geramy; Tahura Etezadi; Ahmad Reza Shamshiri; Mohammad Javad Kharazifard
Abstract
Introduction: An appropriate force system is a perquisite of desirable and predictable tooth movements during orthodontic treatment. Complete knowledge about the generated forces and moments by loops is essential to choose the best one for every situation.The aim of this study was to establish a mathematical ...
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Introduction: An appropriate force system is a perquisite of desirable and predictable tooth movements during orthodontic treatment. Complete knowledge about the generated forces and moments by loops is essential to choose the best one for every situation.The aim of this study was to establish a mathematical equation to bring about a relationship between the L-loop height, width, activation and the produced force.Materials and methods: Six 3D finite element models were designed for L-loop without preactivation bends. Loops were designed with different widths (w) and heights (h). The cross section of wire was 0.016”× 0.022”. The distal end of each model was activated 1 mm in 0.1 mm intervals. The force produced by activation in a 0.1 millimeter increment was recorded. Results: Force findings were different according to the loop parameters defined. The produced force varies from 0.106 to 0.228 N for a 0.1 millimeter of activation and increased from 1.07 to 2.27 N in 1.0 mm of activation.Conclusion: The magnitude of force by L-loop can be estimated through adjustment of vertical part and activation as Increments of activation increased the delivered force while Increasing L-loop height decreased the generated force.
Allahyar Geramy; Tahoora Etezadi
Abstract
Desirable tooth movements need optimal force systems. Loops are employed to move teeth properly. L-loop is used frequently due to its ease of fabrication. The aim of this study is to assess the expected forces and moments when a definite length of wire is bent to form L-loop. In other words, the effect ...
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Desirable tooth movements need optimal force systems. Loops are employed to move teeth properly. L-loop is used frequently due to its ease of fabrication. The aim of this study is to assess the expected forces and moments when a definite length of wire is bent to form L-loop. In other words, the effect of loop height and width on the produced force and moment is evaluated by the finite element method (FEM). Materials and methods: Six 3D finite element models were designed of an L-loop without pre-activation bends keeping the total lengths of wire equal to 24.34+/- 0.5 mm. The cross section of wire was 0.016”× 0.022”. The force produced by activation in a 0.1 millimeter increment was recorded. Results: In model L1, the findings start with 0.086 N in 0.1 mm of activation and increased to 0.88 N in 1mm of loop opening. The pattern of findings was almost the same for other loop designs (L2 through L6) with an increase in findings. M/F ratios were almost constant in a loop design along its activation starting with 3 in L1 and reaching about 1.9-2 in L6. Conclusions: Moment to force ratios were almost constant in a loop design along its activation. increasing width and decreasing height with almost the same length of loop wire can increase force and therefor reduce M/F ratio.
Allahyar Geramy
Abstract
Aim: Being aware of the active and reactive forces and moments in an applied force system helps minimizing side effects and informing patients of future happenings. Wire bends are still used in clinical orthodontics in different ways.
Material and Methods: Three models were designed in SolidWorks 2006. ...
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Aim: Being aware of the active and reactive forces and moments in an applied force system helps minimizing side effects and informing patients of future happenings. Wire bends are still used in clinical orthodontics in different ways.
Material and Methods: Three models were designed in SolidWorks 2006. A step bend of 0.5 mm, a model of two central incisors with their supporting structures, and two blocks with a space and a wire with a combination of two step bends to modify the tooth angulation. Then the models were transferred to ANSYS Workbench Ver. 11.0 for calculations. Different positions of a step bend and the force systems produced by them were assessed.
Results: A gradual decrease of force produced by the step bend between 316 and 308 grams was shown to exist in central step bend position and the extreme one. The moment followed almost the same pattern starting from 15.125 N.mm in center bend position to 14.135 N.mm in its extreme position. In combined step bend model, extrusive/ lingualized movment in one side and intrusive/ labialized in the other side and tipping of the crowns in one and the apices to other side was also shown.
Conclusion: Step bend is not sensitive to its position and almost the same force system is produced in different bend positions (IJO 2006;1: 194-7).