Stress Distribution in Premolars with MOD Cast Metal Restorations

Little information is available on the stress analysis of cast metallic inlays and onlays. Modern design and valuation in order to obtain an adequate framework strength involves numerical simulations. The aim of the paper was to evaluate, the effect of MOD cavity design for cast metal inlays and onlays on stress distribution in teeth structures and restorations. The study was performed on an upper first premolar, using a finite element analysis. The first step of the study was to achieve 3D models in order to design and analyze teeth and cast metal MOD inlays and onlays. Eleven 3D models of maxillary first premolars, prepared for MOD inlays and onlays with different tapers were generated. The mesh structure of the solid 3D model was created using the computational simulation of Ansys finite element analysis software. An occlusal load of 200 N was conducted, and stresses occurring in the inlays, onlays and teeth structures were calculated. For all cavity designs, stresses in the restoration, enamel, and dentin were evaluated separately. The highest stress values were exhibited in the restoration in the most cases. Stresses in the enamel were significantly lower in the teeth prepared for onlays, compared to the teeth prepared for inlays. The MOD restoration on premolars has to distribute the load over a wide surface. Covering the occlusal surface with the restoration, using an MOD onlay, may prevent failure and produce a lower stress values than an MOD inlay. Key-Words: premolar, MOD cavity design, cast metal restoration, inlay, onlay, 3D model, stress analysis.