Three-dimensional Finite Element Analysis Of The Effect Of Brackets Torque In The Process Of Mass Retraction Of Maxillary Anterior Teeth

Objective In this study,a three-dimensional finite element model was established,including the upper teeth,periodontal ligament,alveolar bone,straight wire arch,and micro-implant as anchorage.The biomechanical characteristics of the front tooth torque control were analyzed by using three different torque braces in the process of using micro-implant sliding method.This paper discusses the control of the crown root in the process of anterior teeth to provide biomechanical reference for clinicians.Methods Choose a normal male,the CT data of Dicom in maxillary and upper teeth were obtained by spiral CT scan.Combined with CT data and Mimics 17.0,Geomagic Studio2013,Solid Works 2015 and software such as ANSYS Workbench17.0,three-dimensional finite element models including braces,teeth,periodontal ligament,alveolar bone,arch wire,traction hook,and micro-implant were established and meshed.To simulate the process of pretreatment of anterior teeth in microimplant,using micro-implant as a support and referring the Damon braces data,three different angle displacement loads were applied to the maxillary anterior teeth to simulate different torque bracess: High torque,Standard torque and Low torque,and 1.47 N 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 1.A finite element model of upper maxillary-uppertooth-periodontal-membranecorrection was established.The spiral CT scan obtained more accurate upper jaw and teeth and anatomical structure of three-dimensional information.After the processing of CAD software,the model had good geometric similarity and biomechanical similarity and could meet the requirements of biomechanics of operation.2.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 was different depending on braces torque.The initial displacement of anterior teeth with high torque braces was more likely to labial inclination,while that with low torque braces was prone to tilt the tongue side.3.The stress distribution of periodontal ligament results and size: high torque braces adduction front teeth,upper tooth periodontal ligament stress concentration in tooth neck lip lingual side and root tip,and on the labial side of the incisor in compressive stress distribution was the most concentrated.The stress of periodontal ligament was relatively uniform on the tongue side when the front teeth were collected in the standard torque braces.The compressive stress and tensile stress of maxillary anterior teeth were relatively small.When the anterior teeth were collected in the lower torque braces,the periodontal ligament stress was concentrated in the lingual side of the tooth and the tip of the tooth root.Conclusion 1.Using Mimics 17.0,Geomagic Studio 2013,Solidworks 2015 and ANSYS Workbench 16.0 and other software were used to establish a three-dimensional finite element model.Using three-dimensional finite element analysis could effectively simulate the use of micro-implants as anchorage loading orthodontic force,orthodontic force under different torque braces maxillary anterior teeth and their periodontium stress and displacement of the change,for the mechanical properties of biomechanics analysis provide a reliable platform for the research.2.Compared with the front teeth in the standard torque bracket,the tooth’s lip and tongue should be tilted when the high torque and low torque bracket were retracting anterior teeth.By adjusting the torque Angle of the bracket,the anterior teeth could be controlled to the angle of tilt Angle to achieve better facial appearance.