title: In vitro performance of two-piece zirconia implant systems for anterior application.
abstract: To 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.
  
  
  
  Six 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: 3.6×10(6)×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).
  
  
  
  The 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 (
  
  
  
  p=0.000) between 233.4±31.4N/317.1±42.6N/mm(2) and 404.3±15.1N/549.2±20.5N/mm(2). Fracture forces after TCML were similar to 24h fracture forces.
  
  
  
  Screw-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.
authors.affiliation: Department of Prosthetic Dentistry, Regensburg University Medical Center, 93042 Regensburg, Germany. Electronic address: verena.preis@ukr.de.
authors.forename: Verena
authors.initials: V
authors.lastname: Preis
authors.affiliation: Department of Prosthetic Dentistry, Regensburg University Medical Center, 93042 Regensburg, Germany.
authors.forename: Armin
authors.initials: A
authors.lastname: Kammermeier
authors.affiliation: Department of Prosthetic Dentistry, Regensburg University Medical Center, 93042 Regensburg, Germany.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Handel
authors.affiliation: Department of Prosthetic Dentistry, Regensburg University Medical Center, 93042 Regensburg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Rosentritt
mesh_terms: D003442:Crowns; D000044:Dental Abutments; D059605:Dental Implant-Abutment Design; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D006801:Humans; D008422:Materials Testing; D014025:Titanium; D015040:Zirconium
chemical_list: D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide
keywords: Abutment; Ceramic; Chewing simulation; Fracture resistance; Two-piece implant; Zirconia implant