Comparison of Fracture Resistance and Fit Accuracy of Customized Zirconia Abutments with Prefabricated Zirconia Abutments in Internal Hexagonal Implants

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. Purpose: 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). Materials and 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 1mm/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 (1,430.2N) than the prefabricated abutments (1,064.1N). The mean marginal adaptation of customized abutments revealed a microgap that was increased (11.5μm) over that in prefabricated abutments (4.3μm). Conclusion: 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.