engleski

3DFEM stress distribution analysis of metal-supported vs. non-metal crowns

Crown fracture presents a significant clinical problem, regardless of the material used. Understanding the stress distribution within the crown structure, regarding design and material properties, under occlusal loading is of outmost importance. The 3D finite element method has shown to be representative in investigating the biomechanics of complex structures. The objective was to investigate biomechanics of metal-supported and non-metal crowns under different loading conditions using the 3DFEM model of an upper first premolar, and to compare the results to those of the intact tooth under the same loading conditions. Definitions of geometry and volume for all particular segments of tooth morphology were derived from digitalized upper right first premolar cross-sections. The crowns were designed on circular shoulder type margin. The FEA was performed with NASTRAN software. Mechanical properites were acquired from average values in the literature. The final model consisted of 1684512 for-noded tetrahedral element, 246510 nodes with a total of 739530 degrees of freedom. Boundary conditions were fixed on the outermost layer of alveoalr bone. Single to tripodal contact accumulative static load values of 200N were applied occlusally. The greatest stress concentration was observed within the palatal cusp of the AuPt alloy-acrylic resin crown (-185MPa) and the AuPt-acrylic resin interface4 (-102, 32 MPa). Significant compressive stress values were concentrated at vestibular cervical margin of all-ceramics crown (-7, 39MPa). The highest correlation to the intact tooth values was demonstrated by the ceromer-FRC crown (R=0, 69). Greatest stresses induced during occlusal load involve both metal and veneering material, with acrylic resin on Au Pt alloy being the nost prone to fracutre (-185MPA). The 3D FEM obtained stress distribution explains mechnanical phenomena involved in typical clinical fractures of various types of crowns.

FEM; stress distribution; metal-supported crowns; non-metal crowns

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