title: Comparison of fracture resistance and fit accuracy of customized zirconia abutments with prefabricated zirconia abutments in internal hexagonal implants.
abstract: BACKGROUND
  Customized zirconia abutments are increasingly applied for the fabrication of esthetic implant restorations aimed at imitating the natural situation. These abutments are individually shaped according to the anatomical needs of the respective implant site.
  
  
  OBJECTIVE
  This study sought to compare the fracture resistance and fit accuracy of prefabricated and customized zirconia abutments using an internal hexagonal implant system (TSV®, Zimmer, Carlsbad, CA, USA).
  
  
  METHODS
  Two zirconia abutment groups were tested: prefabricated zirconia abutments (ZirAce, Acucera, Seoul, Korea) and customized zirconia abutments milled by the Zirkonzahn milling system. Twenty zirconia abutments per group were connected to implants on an acrylic resin base with 30-Ncm torque. The fracture resistance of zirconia abutments was measured with an angle of 30° at a crosshead speed of 1 mm/min using the universal testing machine (Z020, Zwick, Ulm, Germany). Marginal and internal gaps between implants and zirconia abutments were measured after sectioning the embedded specimens using a digital microhardness tester (MXT70, Matsuzawa, Tokyo, Japan).
  
  
  RESULTS
  The customized abutments were significantly stronger (1,430.2 N) than the prefabricated abutments (1,064.1 N). The mean marginal adaptation of customized abutments revealed a microgap that was increased (11.5 µm) over that in prefabricated abutments (4.3 µm).
  
  
  CONCLUSIONS
  Within the limitations of this study, the customized abutments are significantly stronger than prefabricated abutments, but the fit is less accurate. The strength and fit of both abutments are within clinically acceptable limit.
authors.affiliation: Private practice, former graduate student, College of Dentistry, Wonkwang University, Iksan, Korea; assistant professor, Department of Dentistry, Wonju College of Medicine, Yonsei University, Wonju, Korea; assistant professor, Department of Prosthodontics, College of Dentistry, Wonkwang University, Iksan, Korea; associate professor, Department of Prosthodontics, College of Dentistry, Wonkwang University, Iksan, Korea; associate professor, Department of Dental Biomaterials, College of Dentistry, Wonkwang University, Iksan, Korea; professor, Department of Prosthodontics, College of Dentistry, Wonkwang University, Iksan, Korea.
authors.forename: Jong-Il
authors.initials: JI
authors.lastname: Park
authors.forename: Yoon
authors.initials: Y
authors.lastname: Lee
authors.forename: Jin-Han
authors.initials: JH
authors.lastname: Lee
authors.forename: Yu-Lee
authors.initials: YL
authors.lastname: Kim
authors.forename: Ji-Myung
authors.initials: JM
authors.lastname: Bae
authors.forename: Hye-Won
authors.initials: HW
authors.lastname: Cho
mesh_terms: D000044:Dental Abutments; D015921:Dental Implants; D003799:Dental Stress Analysis; D006801:Humans; D015040:Zirconium
chemical_list: D015921:Dental Implants; D015040:Zirconium