Finite Element Analysis Of Temporomandibular Joint Stress To Locate Anti-Snoring Apparatus

Objective: By establishing a three-dimensional finite element model of the temporomandibular joint,the stress changes of the joint disc were analyzed under displacement loading of the mandible at different protrusion distances and vertical opening distances.The most suitable ratio of mandibular protrusion/vertical movement was measured to provide a theoretical basis for the production of mandibular advancement devices for the treatment of OSAHS patients.Methods:A patient with OSAHS was selected to make a mandibular advancement device.The maximum protrusion distance of the mandible was measured,and a CBCT scan was performed to obtain CT data of the upper and lower jaw bones,temporomandibular joint disc,etc.Three-dimensional finite element analysis software such as Mimics,Geomagic Wrap,Solid Work,and Ansys were used to establish a three-dimensional finite element model containing structures such as the upper and lower jaw bones,temporomandibular joint,joint disc,and ligaments.Optimize and assemble the mandible,and apply forward and vertical loading to the mandible.The forward displacement is 62%,64%,66%,68%,and 70% of the maximum forward displacement,and the vertical opening distance is 5 mm,6 mm,7 mm,9 mm,and 11 mm.Combine the forward displacement and the vertical opening distance of the mandible,and calculate the surface stress change of the articular disc when the mandible is wearing a snoring preventer.Analyze the data to obtain the minimum mandibular displacement distance of the articular disc stress.Results: A three-dimensional finite element model including upper and lower bones,articular discs,teeth,and periodontal membranes was established.The stress changes in the articular discs were calculated by gradually extending the mandible and rotating it at a certain angle to simulate the vertical opening of the mandible.When the mandibular protraction is constant,the overall stress of the patient’s articular disc increases with the increase of the opening distance.However,when the mandibular protraction is 62%,the minimum stress of the left and right articular discs is 1.16 MPa when they are vertically opened for 6 mm,and the left articular disc is 1.16 MPa,while the right articular disc is 1.44 MPa;When extending 64% forward,the minimum stress of the left and right articular discs is 1.09 MPa and 1.48 MPa when they are vertically opened for 7 mm;When extending 66% forward,the minimum stress of the left and right articular discs appears when opening for 5 mm,with the left articular disc 1.06 MPa and the right articular disc 1.37 MPa;When extending 68%forward,the minimum stress of the left and right articular discs occurred when the mandible was opened for 5 mm,with the left and right articular discs being 1.20 MPa and 1.71 MPa,respectively;When the anterior extension is 70%,the minimum stress of the left and right articular discs respectively occurs when the mandible is opened for 5 mm,with the left and right articular discs being 1.27 MPa and 1.86 MPa,respectively.It is concluded that the minimum stress of the articular disc occurs when the mandible protrudes 66% and opens vertically for 5 mm.Conclusion: When using an anti snoring device to treat moderate OSAHS,the overall stress of the joint disc increases with the increase of the vertical distance of the mandible within the selected effective forward extension and vertical opening distance range.When the mandible extends 66% forward and opens vertically for5 mm,the stress of the left and right joint discs is the smallest.