Finite Element Stress Analysis of IMZ Abutment Designs: Development of a Model

PURPOSE: This article describes the development of a model system for use in finite element stress analysis of three different IMZ abutment designs: original threaded Intra-Mobile Element (IME), Abutment Complete (ABC), and Intra-Mobile Connector (IMC). MATERIALS AND METHODS: A three-dimensional model simulating a cast gold crown restoration attached to an osseointegrated IMZ implant fixture was generated for each abutment design. Each model was discretized into axisymmetric finite elements representing the crown, the various implant system components, and supporting structures. A convergence test was performed to optimize the mesh. Convergence test mesh refinement for the IME, the IMC, and the ABC abutment models resulted in 818 elements, 2,566 nodes; 738 elements, 2,362 nodes; and 663 elements, 2,051 nodes, respectively. Progressive tightening of the retaining screw (preload) was simulated; the degree of screw tightening necessary to prevent opening of the crown-abutment interface in extreme loading (500-N occlusal load at 45 degrees) was determined individually for each system. CONCLUSIONS: Models of three IMZ abutment designs have been refined and the appropriate relative screw preloads determined. This model system is to be used subsequently in stress analysis comparison for the three systems.