Finite Element Analysis Of The Factors Which Affect The Torque Of The Labial And Lingual Brackets With Edgewise And Ribbon Wire

Objective: The factors which affect the torque of the labial and lingual brackets with edgewise and ribbon wire are various,considering from the brackets,inter-bracket distances﹑bracket widths﹑brackets slot sizes﹑brackets slot directions may cause the difference torque between the labial and lingual brackets,researching the reason of different torque caused by the labial and lingual brackets with edgewise and ribbon wire,analying the changes of biomechanical produced by the labial and lingual brackets with edgewise and ribbon wire,to provide a theoretical basis for clinical choosing brackets and wires reasonably.Methods: Establishing the three-dimensional finite model of the labial and lingual brackets with edgewise and ribbon wire.Designing 11 cases of different inter-bracket distances(10mm﹑12mm﹑14mm),bracket widths(2.0mm﹑2.5mm﹑3.0mm),brackets slot sizes(0.018×0.025inch﹑0.022×0.025inch﹑0.022×0.028 inch),brackets slot directions(labial﹑lingual﹑horizontal﹑vertical),making the same center of each group of the model in the labial and lingual brackets rotate clockwise with a rotation angle of 20,collecting the reactive force of the archwire with the increasing torque angle in each model,and drawing a graph of torque moment / torque angle and column chart of maximum torque force value in each condition.Comparing the different torque of the labial and lingual brackets with edgewise and ribbon wire in different cases.Results: 1 、 In all conditions,the changes of torquemoment of the labial and lingual brackets with edgewise and ribbon wire are basically the same,torque moment increasing with the increase of the torque angle;2、The torque of the lingual brackets with edgewise and ribbon wire are bigger than the labial brackets,the torque of the ribbon wire are bigger than the edgewise;3、Torque is applied to the central incisor brackets,The end of the edgewise which generating a reaction force are bigger than the ribbon wire,it has significant vertical displacement;4 、 With the increase of inter-bracket distance,torque moments of the labial and lingual brackets with edgewise and ribbon wire reduce gradually in each condition,and the reducing of lingual brackets with ribbon wire are more significantly;5、With the increase of bracket width,torque moments of the labial and lingual brackets with edgewise and ribbon wire increase gradually in each condition,and the increasing of lingual brackets are more significantly;6、With the increase of brackets slot height,torque moments of the labial and lingual brackets with edgewise and ribbon wire increase slightly in each condition,and the increasing of lingual brackets with ribbon wire are more significantly;with the increase of brackets slot depth,torque moments of the labial and lingual brackets with edgewise and ribbon wire both reduce gradually in each condition,and the increasing of the labial and lingual brackets with ribbon wire are more significantly;7、The change of the brackets slot directions have influence on the torque force value,the direction to the lingual has larger torque,and the change of lingual brackets are more significantly;the torque of vertical brackets slot are bigger than the horizontal.Conclusion: 1、Under the same conditions,the torque moments ofthe ribbon wire are bigger than the edgewise,loading a smaller torque angle for ribbon wire can be applied to a larger torque moment,and having little reaction force on the end of the ribbon wire.2、Under the same conditions,the torque moments of the lingual brackets are significant bigger than the labial,loading a smaller torque angle for lingual brackets can be applied to a larger torque moment.3、The torque moments of the labial and lingual brackets are affected by the inter-bracket distance、brackets width、bracket slot size and brackets slot direction,the inter-bracket distance and bracket width have greater impact.4、In clinical practice,if you want to obtain a larger torque,it can chooses the ribbon wire,and designs wider bracket width,smaller inter-bracket distance,shallower bracket depth and so on in the bracket design and improvement.