In vitro performance of two-piece zirconia implant systems for anterior application

Publication date: Available online 8 April 2016
Source:Dental Materials
Author(s): Verena Preis, Armin Kammermeier, Gerhard Handel, Martin Rosentritt
ObjectivesTo investigate the influence of the implant–abutment connection on the long-term in vitro performance and fracture resistance of two-piece zirconia implant systems for anterior application.MethodsSix groups of two-piece zirconia implant systems (n=10/group) with screw-retained (5×) or bonded (1×) connections were restored with full-contour zirconia crowns. A two-piece screw-retained titanium system served as reference. For simulating anterior loading the specimens (n=8/group) were mounted at an angle of 135° in the chewing simulator, and subjected to thermal cycling (TC: 2×9000×5°/55°C) and mechanical loading (ML: 3.6×10⁶×100N). Failed restorations were examined (scanning electron microscopy). Fracture resistance and maximum bending stress of surviving restorations were determined. 2 specimens per group were loaded to fracture after 24h water storage without TCML. Data were statistically analyzed (ANOVA; Bonferroni; Kaplan–Meier-Log-Rank; α=0.05).ResultsThe bonded zirconia system and the titanium reference survived TCML without any failures. Screw-retained zirconia systems showed fractures of abutments and/or implants, partly combined with screw fracture/loosening. Failure frequency (F) varied between the groups (F=8×: 3 groups, F=3×: 1 group, F=1×: 1 group). The Log-Rank-test showed significant (p=0.000) differences. Fracture forces and maximum bending stresses (mean±standard deviation) differed significantly (ANOVA: p=0.000) between 233.4±31.4N/317.1±42.6N/mm² and 404.3±15.1N/549.2±20.5N/mm². Fracture forces after TCML were similar to 24h fracture forces.SignificanceScrew-retained two-piece zirconia implant systems showed higher failure rates and lower fracture resistance than a screw-retained titanium system, and may be appropriate for clinical anterior requirements with limitations. Failures involved the abutment/implant region around the screw, indicating that the connecting design is crucial for clinical success.



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