Failure Prediction of Dental Restoration Using a CT-based Finite Element and Damage Mechanics Approach.

摘要

To perform dental research on living subjects is expensive and needs to take ethical issues into account. Usage of computer simulation offers a better alternative with the capability of detailed stress analysis. In this study, a computational approach has been developed for failure prediction of dental restoration so that experimental effort can be minimized.;The unit cell modeling method has been applied to predict the constitutive relations of dental composites, enamel and dentin. For most dental composites, particles have high loading and are non-spherical in shape, so a CAD-based modeling technique has been utilized to assist in the preparation of the unit cell models. Through employing the inter-part parametric assembly modeling characteristics of CAD tools, modeling of 3D triphasic unit cells with various particle morphologies and particle volume fractions can be achieved effectively and efficiently. The effect of interfacial debonding damage on the mechanical behavior of a dental composite has been predicted with the application of FE analysis.;In view of the hierarchical structure of enamel and dentin, columnar unit cell models have been designed to determine the anisotropic mechanical behavior. The model for enamel consists of rod and interrod constituents, peritubular and intertubular constituents are used for dentin. In this project, a new method, which integrates nanoindentation, finite element modeling, and artificial neural network techniques, is proposed to determine the elastoplastic stress-strain relations of the four constituents. Thus, the resulting mechanical properties of enamel and dentin in multi-scale include their anisotropic elastoplastic mechanical description parameters and the isotropic elastoplastic stress-strain relations of their four constituents.;To build up a solid computational model of a tooth, a method has been proposed to construct 3D models from 2D scanned images. Facilitated by the CAD tools, the 3D tooth model has been virtually restored with a Class II mesio-occlusal (MO) restoration. The tooth model is triphasic, including the enamel, dentin, and pulp phases. The determined anisotropic elastoplastic mechanical properties of enamel and dentin have also been incorporated into the model. Concerning the radial variation structure of the enamel and dentin, the tooth model has been partitioned into 18 regions, with a specific local coordinate system for each region. Stress analysis and failure prediction of the restoration have then been conducted using the established 3D assembly FE model. The application of the new method in constructing 3D FE models from 2D scanned images is not limited to the dental industry but also to other medical applications. It can be applied in creating patient-specific models of any body tissue part using CT scanning images.