The in vitro investigation of fatigue strength and fracture resistance of ti-base zirconia abutment supported zirconia restorations with distala single extension

The purpose of this invitro study was to evaluate the mechanical complications and fracture resistance of two hybrid abutment supported distal cantilevered zirconia restorations after dynamic and static loading. Implant supported restorations simulating a mandibular first and second premolar with distal cantilever were designed and milled using CAD/CAM system and divided into two groups according abutment configuration: Group 1; one of the abutments in each sample with anti-rotational part (n=10) and Group 2; abutments without anti-rotational part (n=10). Each of the hybrid abutments and the inner surface of the zirconia restorations were tribochemically coated. Then all abutments were fixated on the implants at 30 Ncm torque value and monolithic zirconia crowns were adhesively cemented onto the abutments. After cementation procedures each group was subjected to 1.200.000 cycles of thermo‐mechanical fatigue loading in a dual‐ axis chewing simulator at 50 N load for dynamic loading. Then the specimens were subjected static loading in a universal testing machine. Mode of failure was determined under the Scanning Electron Microscope. During chewing simulation, the survival and success rate of restorations is %100. The average value of fracture resistance for Group 1 and Group 2 were 706.2 N and 873.7 N respectively. According to the static loading data, the maximum fracture resistance of all tested samples were above the force values in the intraoral posterior area. Although the difference between the groups was not statistically significant, group samples without anti-rotational parts showed higher fracture resistance. Within the limitations of this in vitro study, it can be said that Ti-base abutment supported monolithic zirconia restorations with distal extension may be used in the posterior area in the presence of correct occlusal adaptations and occlusal contacts.