Abstract: Objective：To investigate the control of the crown and root of maxillary teeth in en-mass retraction with different braces torque. Methods: Choose a normal male's tooth as sample. 3D software: Mimics,Geomagic and Solidworks were used to reconstruct by the CT data, and the maxillary three-dimensional finite element model was established in Ansysworkbench.Using micro-implant as anchorage and referring the Damon bracket data, three different angle displacement loads were applied to the maxillary anterior teeth to simulate different torque brackets: High torque, Standard torque and Low torque, and 150g force of the adduction was added as a whole. The stress distribution in periodontal tissue and the crown and root of initial displacement were calculated．Results ：In the process of adducting anterior teeth, the initial displacement of the crown and root and the stress distribution of the periodontal ligament were varied with different torque braces. The movement of the anterior teeth is different depending on braces torque. The initial displacement of anterior teeth with high torque braces is more likely to labial inclination, while that with low torque braces is prone to tilt the tongue side .Conclusion：In the process of adducting anterior teeth, a better therapeutic effect and better face can be achieved via adjusting the brackets torque angle to control the inclination angle of the anterior teeth.

Key words: Torque of brackets, Three dimensional reconstruction, Three dimensional finite element analysis