Allahyar Geramy; Ahmad Sodagar; Omid Mortezaee
Abstract
Aim: Anchorage management is a challenging problem while retracting anterior segment in orthodontic treatments. The purpose of this study is to evaluate the effect of anterior teeth labiolingual inclination on the amount of anchorage loss and distance of anterior retraction.Methods and Materials: Six ...
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Aim: Anchorage management is a challenging problem while retracting anterior segment in orthodontic treatments. The purpose of this study is to evaluate the effect of anterior teeth labiolingual inclination on the amount of anchorage loss and distance of anterior retraction.Methods and Materials: Six 3D computer models of an upper anterior segment were designed in SolidWorks 2006 (SolidWorks, Concord, Massachusetts, USA).The models contained supporting structure, upper central and lateral incisors, their PDLs, the brackets and an anterior retraction arch wire with two vertical open loops. The models were the same except for the torque of anterior teeth which were 0, 5, 10, 15, 22, and 35 degrees consequently. ANSYS Workbench Version 12.1 (ANSYS Inc., Southpointe, Canonsburg, PA, USA) was selected for the analysis. At each analysis, the end points of the arch wire were displaced distally simulating the anterior retraction arch wire activation. The displacement produced in the labio-mesio-incisal point angle and the mesializing force applied to the terminal molar was assessed.Results: Torque degree of 0 to 22 exerting almost equal force on anchorage unit during retraction while 35 degrees of torque causing more reciprocal force. Ten degrees of anterior torque resulted in maximum displacement of anterior segment.Conclusions: To have maximum anchorage and faster anterior teeth movement during retraction degree of torque suggested to be about average and neither too protruded nor uprighted.
Allahyar Geramy; Reza Jelodar; Hasan Salehi
Abstract
Aim: The aim of this study was to assess the effects of different loop forms in continuous arch technique on its force characteristics in the anterior retraction arch wires.Material and Method: Six 3D finite element models were designed of an anterior retraction arch wire formed and included four average ...
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Aim: The aim of this study was to assess the effects of different loop forms in continuous arch technique on its force characteristics in the anterior retraction arch wires.Material and Method: Six 3D finite element models were designed of an anterior retraction arch wire formed and included four average sized anterior brackets and the palatal wall of the bracket slot of the canines. The models were similar except for the height and angle of the loop legs. The left side loop was kept constant in all stages of the study while modifying the right side loop height or vertical leg's angulations. SolidWorks 2006 was selected for the modeling phase and ANSYS Workbench Ver. 11.0 for the calculations. Mesializing force on molar, medially directed force on canine, and anterior retraction forces were evaluated.Results: According to the results, loop height in one side cannot affect the other side loop force characteristic directly; A gradual increase of the force difference between two side of the anterior retraction arch wire is shown. The mesializing force on molar is also increased with almost the same manner. The other findings related to loop leg divergence shows a difference between two sides but the differences are almost the same with varying degrees of divergence. Although the forces are not the same in both sides but the difference remained almost constant.
Conclusion: Arch wires may seem to be symmetric but may act asymmetric. Difference in anterior teeth retraction may be due to some asymmetries in arch wire fabrication which needs further considerations.
