Three-dimensional finite element study on the effect of posterior tooth forward movement on temporomandibular joint stress in orthodontic reduction patients

Shang Yonghui; Li Shuai; Liu Yicong; Zhao Qihang; Liu Wen

doi:10.12307/2024.822

Abstract：BACKGROUND:Temporomandibular joint disorders are closely related to high stress in temporomandibular joint.With the change of molar position after tooth reduction extraction,the establishment of new occlusal relationship often leads to the change of internal stress environment of the temporomandibular joint. OBJECTIVE:To analyze the stress distribution of temporomandibular joint in patients undergoing orthodontic reduction tooth extraction with different degrees of molar forward movement using the three-dimensional finite element model of the maxillary complex and temporomandibular joint. METHODS:A case of individual normal occlusal patient was selected from the Orthodontics Department of Qingdao Municipal Hospital,Shandong Province,and the finite element models of 1/3 anterior molar space(extraction of four second premolar teeth)before and after reduction and 2/3 anterior molar space(extraction of 4 second premolar teeth)after reduction were established based on the cone-beam CT and MRI data.ABAQUS software was used to analyze the stress distribution of various parts of the temporomandibular joint during the interposition of tooth tips. RESULTS AND CONCLUSION:The stress distribution of the condyle,articular disc,and osteoarticular fossa in the model before and after the reduction was basically the same.The stress of the condyle was mainly distributed in the anterior and apical part of the condyle,the stress of the articular disc was mainly distributed in the middle band and lateral part of the articular disc,and the stress of the articular fossa was mainly concentrated in the anterior and apical part of the articular fossa.However,the equivalent stress value of the condyle,articular disc and articular fossa decreased after reduction.After orthodontic reduction extraction,the equivalent stress values of condyle and articular disc in the 1/3 anterior molar space model were smaller than those in the 2/3 anterior molar space model.From the perspective of biomechanics,orthodontic reduction extraction can reduce the stress of the temporomandibular joint and provide a good biomechanical environment.