Cheek Soft Tissue And The Denture Occlusal Interference Detection And Correction

The main tasks of the thesis include 3D reconstruction of maxillofacial models based on CT images, the motion simulation of osseous tissues and soft tissues in occlusal processes, interference detection and correction on the tooth contact surface. The simulation operation can be controlled by the interactive processing in the occlusal rehabilitation simulation system.Based on a series of CT images, selecting maxillofacial soft tissues and sclerous tissues as investigated examples, the models are established for oral cavity restoration and the simulation of soft tissue deformation. The key issues in the process of reconstruction, such as distinction of the adjacent face that joins the neighboring tissues, establishment of the adjacent relationships, fine tissues reconstitution, are described and solutions to the problems are proposed. By several operations, including the contour extraction, the construction of public outlines, the smoothing appearance of models, according to medical features, maxillofacial tissues are reconstructed. The 3D models are fine to show different tissues and reflect characteristics of neighboring tissues. The method is also applicable to reconstruction of other 3D organ models.The three main occlusive means of mandibula are studied by using the method that combines different motions. Achieve synchronized motion of osseous tissues and soft tissues with collision detection. The finite element method is often used in soft tissue deformation, but the method is hard to satisfy the need of real-time requirement for big amount of computation. As the deformation of soft tissues in the cheek with the fixed characteristics, based on the models of maxillofacial soft tissues that composed of triangular meshes, the rule of soft tissue deformation is presented by functional expressions that describe the motions of different vertices, according to the feature of soft tissue deformation, Poisson coefficient, Bezier fitting curve and time variable. Realize adjustments of soft tissue deformation by setting parameters. The simulation results show the method has good effects.If conflicts occur between the tooth and surrounding soft tissues, it will cause pain of the local soft tissues. Ray tracing collision detection algorithm is used to get collisional areas of surrounding tissues around the tooth. By making use of the method that combines direct adjustment with interpolation method, the conflict areas are adjusted with good effects and make the tooth model meet individual requirement.Finally, conclusions of the thesis are made. The deficiencies and suggestions are proposed for further research.