Associate Professor, Orthodontics Department, Tehran University of Medical Sciences (TUMS), Dental Research Center, Tehran University of Medical Sciences (DRC-TUMS)



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 in center bend position to 14.135 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).