Zheng et al. compared the stress distribution of the same veneering ceramic on different cores and concluded that the zirconia core was clearly different from other materials with higher tensile stresses at the veneer core interface because the increasing differences between the elasticity modulus of the core and the veneer transmitted higher stress concentrations to the cores. Consistent results were observed in our study as e.max CAD, which has greater elasticity modulus difference (e.max CAD-e.max Ceram 95–64 GPa; Vita Suprinity-VM-11 65–65 GPa), showed higher stress concentration (33.8 MPa) than Vita Suprinity core (30.7 MPa).

In order to validate the model, it is possible to compare the FEA results with the in vitro test results and previous studies in the literature. FEA showed similarity with the in vitro test in the stress type. Compressive stress values varying from − 1074 to − 1110 MPa, higher than tensile stresses (322–374 MPa), for crown models and compression loads (negative values) were predominant as in the load-to-failure test. The stresses were concentrated in the central groove and fissure as observed in the fracture pattern on the remnants of the load-to-failure test. After the load-to-failure-test, there was no chipping or fracture in the cervical area. This was confirmed by FEA as no stress was concentrated in this area (Fig. 3a–d). Additionally, veneered e.max CAD crowns with higher stress concentration on the cores had a lower failure load than veneered Vita Suprinity crowns. Similar to the FEA results of the previous studies, different restorative materials did not change stress distributions on the bone and they were concentrated in the cortical bone around the implant neck in accordance with the literature. The relation between these findings validates our FEA model.