Mechanics Research On The Distal-Occlusal Cavities Of The Mandibular Second Molar

Unsuitable bad retention form of the distal-occlusal restored molar often makes the restoration broke off or the tooth tissue split in clinical medicine.Therefore,how to find the most optimal retention form which keeps the mechanical property of the tooth tissue and filling material is an important research topic of dental biomechanics.In this thesis,the CT scanner data of the mandibular second molar were rebuilt to 3D model with the Rapid Prototyping systems of the Materialise's Interactive Medical Image Control System(MIMICS).With the use of the digital image processing Matlab program and the Geomegic inverse engineering software,the 3D geometry model was established.Based on the rebuilt geometry model,the 3D finite element model was established with ABAQUS software.This operation can reduce the complexity of the modeling process,and improve the geometry accuracy and modeling efficiency.The obtained finite element model provided a good starting point for numerical optimization.Choosing the parameters of the ladder-shape retention form in the BlackⅡcavity of DO small caries as design variables,our FEM analysis results indicate that the stress in dentine is a nonlinear function of the design parameters.With the use of the response surface method,a set of optimal solutions of the design parameters are obtained(the included anger between buccal-iingual direction and long axis isθ= 20°and the distance between axial wall and distal wall is L = 2.2 mm).The result obtained in this study provided some valuable references for the clinical treatment of oral disease.