Biomechanical evaluation of a new standard temporomandibular joint prosthesis and screw arrangement optimization: A finite element analysis.

Abstract Background: Artificial total joint replacement is an important method of temporomandibular joint (TMJ) reconstruction, which has been advocated for TMJ osteoarthrosis, ankylosis, tumors and other diseases. We designed one type of a standard TMJ prosthesis fit for Chinese patients. This study explores the biomechanical behavior of the standard TMJ prosthesis using finite element analysis and selects an optimal screw arrangement scheme for clinical application. Methods: A female volunteer was recruited for a maxillofacial computed tomography (CT) scan, then the Hypermesh software was used to establish a finite element model of a mandibular condyle defect repaired with an artificial TMJ prosthesis. LS-DYNA software was used to calculate the stress and deformation under a simulated maximum bite force loading. Also, the forces of screws under different numbers and arrangements were analyzed. Meanwhile, we designed an experiment to verify the calculation model.Results: The average maximum stress of the fossa component of the standard prosthesis model was 19.25 MPa. The average maximum stress of the condyle component was 82.58 MPa, mainly concentrated near the top row hole. The fossa component should be fixed with at least 3 screws, and the optimal number of screws was 4. The condyle component should be fixed with at least 4 screws, and its optimal number was 6. The best scheme of screw arrangement was determined. The results of the verification experiment showed that the analysis was reliable.Conclusions: The stress distribution of the standard TMJ prosthesis is uniform, meanwhile, the number and arrangement of the screws significantly affect the contact force of the screws.