Stress Distribution in Maxillary First Molar Periodontium by Using Straight Pull Headgear with Vertical and Horizontal Tubes: A Finite Element analysis

One of the most effective ways for distal movement of molars to treat Class II malocclusion is using extraoral force through a headgear device. The purpose of this study was the comparison of stress distribution in maxillary first molar periodontium using straight pull headgear in vertical and horizontal tubes through finite element method.
Based on the real geometry model, a basic model of the first molar and maxillary bone was obtained using three-dimensional imaging of the skull. After the geometric modeling of periodontium components through CATIA software and the definition of mechanical properties and element classification, a force of 150 g for each headgear was defined in ABAQUS software. Consequently, Von Mises and Principal stresseswere evaluated. The statistical analysis was performed using T-paired and Wilcoxon nonparametric tests.
Extension of areas with Von Mises and Principal stresses utilizing straight pull headgear with a vertical tube was not different from that of using a horizontal tube, but the numerical value of the Von Mises stress in the vertical tube is significantly reduced (P0/05).
Based on the results, when force applied to the straight pull headgear with a vertical tube, Von Mises stress are reduced significantly in comparison with the horizontal tube. Therefore, to correct the mesiolingual movement of the maxillary first molar, vertical headgear tube is recommended.