A Prospective Clinical Study of Alumina-Toughened Zirconia Abutments for Implant-Supported Fixed Restorations with a Mean Follow-up Period of 6.9 Years

Purpose: The goal of this study was to compute the estimated cumulative survival and success rates of alumina-toughened zirconia (ATZ) abutments used for external connection-type implant-supported fixed dental prostheses (FDPs) after a mean follow-up of 6.9 years (82.3 months). Materials and Methods: From May 1998 to July 2016, patients who provided informed consent and received implant-supported restorations with ATZ abutments were recruited. Clinical performance of zirconia abutments was evaluated using survival analysis. Failure was defined as the removal of the restoration due to zirconia abutment fracture, and complications included both failure and abutment screw problems. Survival and success were the counterparts of failure and complications, respectively. The effects of restoration-related factors (restored area, type of prosthesis, and implant system) on the survival and success of the abutments were estimated. Results: A total of 231 patients were included in this study. One hundred twenty-six implantsupported single-unit and 204 multiple-unit FDPs were evaluated. All the placed implants had the external hex connection. The estimated cumulative 5-year, 7-year, and 10-year survival rates (95% confidence interval [CI]) of zirconia abutment-supported FDPs were 97.3% (95.5% to 99.1%), 96.8% (94.8% to 98.8%), and 94.1% (90.4% to 97.8%), respectively. The estimated cumulative 5-year, 7-year, and 10-year success rates (95% CI) were 94.1% (91.4% to 96.8%), 90.8% (87.3% to 94.3%), and 80.1% (73.6% to 86.6%), respectively. The type of prosthesis (P = .001) and implant system (P .001) were the significant factors in the success of zirconia abutment-supported FDPs. Conclusion: Prefabricated ATZ abutments have a high predictability of survival at 10 years when used in implant-supported FDPs that replace both anterior and posterior teeth. However, the success of zirconia abutments was significantly influenced by the type of prosthesis and implant system. Schlagwörter: alumina-toughened zirconia abutment, implant-supported fixed restoration, implant system, prosthesis type, survival analysis