Three-dimensional finite element analysis on the effect of posterior cross-bite of individual teeth on temporomandibular joint / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To analyze the stress distribution of temporomandibular joint (TMJ) in posterior cross-bite of individual teeth and in normal occlusion during the intercuspal occlusion (ICO).</p><p><b>METHODS</b>On the basis of the geometric TMJ model of normal occlusion, the TMJ finite element model of posterior cross-bite of individual teeth was reconstructed. The occlusal force and boundary conditions were applied on the model. Using three-dimensional finite element method (FEM), the stress distribution of TMJ in posterior cross-bite of individual teeth was analyzed by simulating the ICO load.</p><p><b>RESULTS</b>No significant differences were found in stress distribution in various TMJ structures between posterior cross-bite of individual teeth and normal occlusion. However, the stress level was higher and the stress distribution was more inhomogeneous in posterior cross-bite of individual teeth than in normal occlusion. In the cross-bite malocclusion of individual posterior teeth, the maximum of von Mises stress was 0.792 MPa, the maximum principal stress was 0.598 MPa and the minimum principal stress was -0.744 MPa. But in normal occlusion, the maximum of von Mises stress was 0.592 MPa, the maximum principal stress was 0.395 MPa and the minimum principal stress was -0.554 MPa.</p><p><b>CONCLUSIONS</b>When the ICO load was applied, the stress distribution of TMJ was more inhomogeneous and the stress level was higher in posterior cross-bite of individual teeth than in normal occlusion.</p>

Three-dimensional reconstruction of temporomandibular joint with CT and MRI medical image fusion technology / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the method of the three-dimensional reconstruction of temporomandibular joint (TMJ) on the basis of CT and MRI medical image fusion technology, which establishes good foundation for a series biomechanical studies and clinical analysis.</p><p><b>METHODS</b>The geometric data for the TMJ model were obtained from a young and healthy male volunteer. Twelve spherical markers were located on the regions of both TMJ and mental tubercles, where CT and MRI scans can reach. The three-dimensional geometric of the hard and soft tissues of TMJ was reconstructed by CT and MRI scans data, which was based on the registration procedures of spherical markers located on the face of the volunteer.</p><p><b>RESULTS</b>The three-dimensional geometric model of TMJ was obtained, including hibateral articular disc, mandible, glenoid fossa and inferior teeth, and it had better geometric similarity. The results showed that the methods of three-dimensional reconstruction of TMJ with CT and MRI medical image fusion technology can be operated easily and promptly. The constructed model had good morphology.</p><p><b>CONCLUSION</b>It is feasible to construct the three-dimensional model of TMJ on the basis of the registration procedures of spherical markers and CT-MRI medical image fusion technology. It has the advantage of simulating both hard and soft tissues reasonably. The model well expresses the shape of the TMJ.</p>