Objectives: the aim of this study is to detect the type of failure and quantify strains around titanium or zirconia abutment–implant assemblies using a biologically simulated mandibular model. Materials and methods: Ten titanium fixtures were embedded in ten simulated mandibular models in the premolar area. Five titanium abutments with ceramo-metallic crowns and five zirconia abutments with zicrconia crowns were attached to the implants. Both groups were fatigued in cyclic loading machine for 10,000 cycles, then loaded till failure in static loading machine and strains around each group were collected. Fractured samples were analyzed by scanning electron microscopy (SEM). Results: Fracture resistances of zirconia crowns were lower than that of ceramo-metallic crowns. This might be due to cement failure between the zirconia abutments and the crown, and not due to a defect in the material itself as shown by the scanning electron microscope. Also, insignificant differences were found in the strains generated around both the zirconia and the titanium abutments at a load of 150 N. While at load of fracture, higher strains were generated around the titanium abutments when compared with zirconia abutments. Conclusion: All- ceramic zirconia crowns with zirconia abutments had a favorable effect on the stress distribution when compared with ceramo-metallic crowns with titanium abutments. Also, both Zirconia and titanium abutments could withstand the functional loads developed during physiologic chewing in the premolar area. Consequently, zirconia abutments could be considered to be a valid alternative to metal abutments in esthetically demanding areas.