1 Professor Dental Research Center and Orthodontics Department Tehran University of Medical Sciecnes

2 Assistant Professor, Babol, University of Medical Sciences

3 Orthodontist



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.