Finite Element Stress Analysis of Cast Metal Inlays Restored Posterior Teeth

摘要

Cast metal inlays have overall characteristics unavailable in any other restorative procedure, including low restoration wear, low wear of opposing teeth, lack of breakage, burnishability, malleability, and proven long term service. They replace missing teeth structures, without doing anything to reinforce the remaining structures. Stress concentrations can manifest themselves in various forms of failures. The aim of the study was to investigate the effect of preparation design on stress distribution in molars with different class II preparations and restored with cast metal inlays. 3D models of premolars and molars were created: intact teeth, unrestored teeth with class II preparations with different tapers (between 0 and 10 degree); the same teeth restored with metalic inlays. The geometries of the intact teeth were obtained by 3D scanning using a manufactured device. With Rhinoceros modeling program the preparations and the appropriately inlays were designed. These were exported in Ansys finite element analysis software for structural simulations. Stresses were registred around the occlusal contact areas. For the studied cases, the stress values were not significant influenced by the taper of the preparation. In the teeth restored with cast metal inlays, the von Mises equivalent stress values were similar to those in the intact tooth. From biomechanical point of view, it was demonstrated that class II cast metal inlays on posterior teeth restore the original strength of the teeth. Taking into account the other characteristics of these restorations, they remain the standard of care for long-term rehabilitations. A taper between 0 and 10 degree of the preparation is not decisive for the stress values.