Finite Element Stress Analysis of Stainless Steel Crowns

Abstract

Background: Though stainless steel crowns (SSCs) have often been stated as the best restorative modality, there are limited studies demonstrating its efficacy in restoring the functional integrity of the primary dentition. Hence has arisen, the necessity to establish the supremacy of SSCs. Aim: Evaluation of the efficacy of SSC to with stand compressive (0°), shearing (90°), and torsional (45°) stress when used as a restorative material. Settings and Design: The study design employed four finite element models, each with differing amounts of tooth structure, which were exported to ANSYS software and subjected to an average simulated bite force of 245N. Materials and Methods: Four maxillary deciduous primary molars restored with SSCs (3M ESPE) were subjected to spiral computed tomography (CT) in order to obtain three-dimensional (3D) images, which were then converted into finite element models. They were each subjected to forces along the long axis of the tooth and at 45°and 90°. Results: The maximal equivalent von Mises stress was demonstrated in the SSCs of all the models with only a minimal amount observed in the underlying dentine. In all situations, the maximal equivalent von Mises stress was well below the ultimate tensile strength values of stainless steel and dentine. Conclusion: Even at maximal physiologic masticatory force levels, a grossly destructed tooth restored with SSC is able to resist deformation.

Keywords

• Deciduous molar
• finite element analysis
• fracture resistance
• stainless steel crowns