The Effect of Fixture Neck Design in a Realistic Model of Dental Implant: A Finite Element Approach

Abstract

The aim of this work is to develop an accurate finite element model able to reproduce a standard experimental set-up for the evaluation of mechanical failure of a dental implant system. The considered system is composed of a fixture, an abutment and a connecting screw. We analysed the behaviour of the implant system considering three different designs of the fixture, in order to establish which one provides the better mechanical behaviour. After the definition of the numerical models, loading conditions were selected in order to reproduce the same stress state found in previous mechanical failure tests. Preloading and functional loading conditions were simulated. The analysis of the numerical results shows that the structure yielding is due to the fixture neck plastic deformation, that increases the load eccentricity and then the bending stress on the connecting screw. Only slight differences were found between the three implant systems in the amount and distribution of stress. The model reproduces properly the implant systems and the experimental set-up. The goodness of the model can be summarised as: realistic geometrical structure, elastoplastic model for the material description, correct definition of the contacts and the existing tolerance among the different system components, reproduction of the preloading stress condition. The present study permitted to define a valid procedure for the realization of numerical models of implant systems.

Novel Ball Head Screw and Screwdriver Design for Implant-Supported Prostheses With Angled Channels: A Finite Element Analysis

“…The goodness of the model can be summarized as a realistic geometrical structure and elastoplastic model for the material description, affording correct definition of the contacts and existing tolerance among the different system components, and with good reproduction of the preloading stress condition. 28 Few studies have addressed the influence of screw head design tested over a range of angles of application of the respective screwdriver, the torque value at which the screw head strips, or the torque at which screwdriver engagement fails. Spencer et al 29 tested the behavior of titanium screws with four different head designs under different angulations.…”