3D FEA stress distribution analysis of metal-ceramic crown under occlusal load

Metal-ceramic crown fracture is still a significant clinical problem Design and material properties improvement implies understanding the stress distribution within the crown structure, and the crown interaction with tooth and its supporting structures during occlusal loading. The 3D FEA has shown to be representative in investigatin the biomechanics of complex structures. The objective was to create a 3D model of a metal-ceramic crown on an upper first premolar with its supporting structures, and to investigate aspects of its biomechanics under different loading conditions. Material and methods. Definitios of geometry and volume for all particular segments of tooth morphology were derived from digitalized upper right first premolar cross-sections. The metal-ceramic crown was designed on a shoulder type margin. The FEA was performed with NASTRAN software. Materials' mechanical properties were acquired from average values of the literature. The final model consisted of 1.684, 512 four-noded tetrahedral elements, 246510 bides wutg a titak if 739, 530 degrees of freedom. Boundary conditions were fixed on the outermost layer of the alveolar bone. Single to tripodal conctact accumulative static load values of 200N were applied occlusally. Results. The greatest stress concentration was observed within the palatal part of the ceramics (-30.00 MPa) and the metal core (-28.44 MPa). Significant compressive stress values were concentrated within ceramics at the palatal cervical crown margin (-23.75 MPa). Conclusions. Greatest stresses induced during occlusal load involve both metal and ceramics. The #D FEA of stress distribution explains mechanics involved in typical cllinical fractures of metal-ceramic crowns.