To evaluate the effect of restorative materials on stress distribution of endodontically treated teeth, the 3D models of an endodontically treated mandibular fi rst molar, restoration, and cement layer were created. Three different materials(composite resin, ceramage and ceramic) were studied and two loading conditions(vertical and oblique load) were simulated. Mohr-Coulomb failure criterion of enamel, dentine, endocrown and cement were evaluated separately. It is indicated that under both loading conditions, the highest values of Mohr-Coulomb failure criterion were observed in Ceramage-restored group for remaining tooth structure while in ceramic-restored group for the restoration. Compared to composite resin and Ceramage, ceramic endocrown transferred less stress, namely was more protective to the tooth structure. To evaluate the effect of restorative materials on stress distribution of endodontically treated teeth, the 3D models of an endodontically treated mandibular fi rst molar, restoration, and cement layer were created. Three different materials (composite resin, ceramage and ceramic) were studied and two Mohr-Coulomb failure criterion of enamel, dentine, endocrown and cement were isolated separately. It is indicated that under both loading conditions, the highest values ​​of Mohr-Coulomb failure criterion were observed in Ceramage Compared to composite resin and Ceramage, ceramic endocrown transferred less stress, that was more protective to the tooth structure.