Two-piece zirconia oral implants withstand masticatory loads: An investigation in the artificial mouth

Abstract

ObjectiveTo evaluate the fracture resistance of two-piece zirconia oral implants after long-term thermomechanical cycling in an aqueous environment. Non-loaded samples and a one-piece implant system served as control groups. MethodsA total of 48 zirconia implants were evaluated: 16 one-piece implants (ATZ; Group A) and 32 differently connected two-piece implants (16 screwed, Group B; 16 bonded, Group C) made of Y-TZP-A (implant+abutment; B) and Y-TZP-A/ATZ (implant/abutment; C), respectively. These groups were divided into two subgroups composed of 8 samples. The samples of subgroups 1 (A1, B1, C1) were not exposed to any cyclic loading, whereas subgroups 2 (A2, B2, C2) were loaded with 10 million cycles (98N). Subsequently, all 48 implants were statically loaded to fracture. ResultsA constant load on distinct lever arms resulted in different exerted bending moments during the dynamic loading (A2: 23.4Ncm, B2: 17.9Ncm, C2: 32.3Ncm). All implants survived the long-term thermomechanical cycling. For the static loading the following average bending moments were calculated: A1/A2: 362/399Ncm; B1/B2: 398/346Ncm; C1/C2: 380/252Ncm. Foregoing dynamic loading significantly increased fracture resistance of Group A implants, whereas Group B/C implants showed significantly decreased values. Potentially owed to the experimental setup in an aqueous environment of 60°C, 5/8 C2 samples showed mobility between implant and abutment due to debonding after dynamic loading conditions. SignificanceThe evaluated ceramic implant systems seem to be able to resist physiological chewing forces long-term. Within the limitations of the experimental setup, the connecting mechanism of Group C implants might be a weak point.