Effect of Abutment Preparation and Fatigue Loading in a Moist Environment on the Fracture Resistance of the One-Piece Zirconia Dental Implant

Purpose: One-piece zirconia dental implants have been widely used in Europe for many years. This in vitro study was done to evaluate the effect of abutment preparation and fatigue (cyclic) loading in a moist environment on the fracture resistance of the one-piece zirconia dental implant. Materials and Methods: Twenty-four Cera Root zirconium oxide dental implants, divided into three groups of eight, were used in this study: group 1 (control group): implants with no preparation, tested in a dry environment; group 2: implants with no preparation, tested in a moist environment (simulating clinical conditions); and group 3: implants after abutment preparation tested in a moist environment. All implants received IPS e.max porcelain crowns. All samples were subjected to nearly 1 million cycles of sinusoidal fatigue loading (-10 N to -200 N) in a universal testing machine. The postfatigue samples were loaded to fracture. Significant differences (alpha = .05) in mean fracture loads were statistically analyzed. Results: There was no catastrophic failure of any of the implants during the fatigue tests. The mean (SD) of the fracture loads in postfatigue load-to-failure tests were: group 1: 1,202.9 (62.6); group 2: 1,164.6 (73.8); and group 3: 953.5 (103). Analysis of variance (ANOVA) and post hoc Tukey-Kramer contrast revealed a statistically significant difference (P < .05) between the mean fracture load of group 3 and those of groups 1 and 2, but no significant difference (P > .05) between groups 1 and 2. Conclusion: While there was a statistically significant adverse effect of abutment preparation and fatigue loading in a moist environment on the postfatigue implant failure load, the load-to-fracture mean of surface-prepared implants after fatigue tests was nevertheless significantly higher than the mean fracture load of the crowns (P < .05) as well as the minimum load-bearing requirement (300 N) for anterior restorations. Abutment preparation in a one-piece zirconia implant is therefore considered clinically safe and acceptable.