Dynamic Biomechanical Study Of The Effect Of Intermaxillary Traction On The Stress Distribution Of Temporomandibular Joint During Opening Movement In Clear Aligner Therapy

Objective:In this experiment,a biomechanical simulation model including the temporomandibular joint,upper and lower dentition?clear aligner ?upper and lower jaws was established,investigating the effect of the thickness of the clear aligner and the diverse intermaxillary traction on the stress distribution of the temporomandibular joint in the functional open movement of the mandible,and provide a certain reference for the selection of a reasonable traction force value for orthodontic treatment.Methods:Volunteer skull multi-slice spiral CT data was used as the basis for modeling.Using Mimics 17.0,Geomagic Studio,Abaqus and other software,3D reconstruction of dentition,jaw,temporomandibular joint,and clear aligner Metamodel.Simulate the functional opening movement of the mandible,class II intermaxillary traction was performed on the invisible appliance group(group A)and the invisible appliance group(group B),with force values of 0.06 N / mm,0.08 N / mm,and 0.20 N / mm,solve the calculation to obtain the cress distribution of the temporomandibular joint.Results:In this study,a three-dimensional finite element model of " temporomandibular jointupper and lower dentition-clear aligner-upper and lower jaws was successfully constructed,which simulated the wearing of clear aligner with a thickness of 0.75 mm(Group A)and no wearing of clear aligner(Group B).The comparison of the results of the loaded type II traction force and the unloaded type II traction force shows that the cress of the temporomandibular joint becomes larger after the loading type II traction;and the cress increased with the increase of the traction force value.Under the same traction,when the opening degree is 5mm,the contact stress is significantly larger than other opening states.The results of group B are less different from those of group A.Conclusion:The biomechanical simulation model constructed in this study is consistent with the actual situation,and it can lay a foundation for the biomechanical study of the temporomandibular joint of the mandibular functional state.With the intermaxillary traction force of the same force value,the stress distribution of the temporomandibular joint is affected by the opening degree,and the initial cress is the largest;at the same opening degree,the small force values type II traction has a small effect on the cress distribution of the temporomandibular joint.Whether or not wearing an appliance during mandibular opening has no effect on the cress distribution of the temporomandibular joint area.