In vitro study reveals screw access holes reduce fatigue resistance in zirconia abutments regardless of 3D printing or milling, indicating geometric design outweighs manufacturing method.
The aim of this study is to evaluate the effect of the abutment manufacturing method (CAD/CAM milling or 3D-printing) and the presence of a screw access hole on the fatigue behavior of adhesively cemented zirconia restorations. Zirconia (3YSZ) discs, representing prosthetic abutments (Ø= 10 mm, 3 mm in thickness) were fabricated by simulated CAD/CAM milling (M) or lithography-based 3D-printing (3D), either with a screw access hole (Ø=2.5 mm, filled with resin composite) or without (Rigid) and allocated into four groups: M-Screw, M-Rigid, 3D-Screw and 3D-Rigid. Restorative zirconia discs (4YSZ; Ø=10 mm, 1 mm thickness) were adhesively cemented to the abutments using a dual-cure resin cemented. Cyclic fatigue test was performed ( n = 15). Data were analyzed using Kaplan-Meier, Log-rank (Mantel-Cox) and Two-way ANOVA supplemented by fractography and finite element analysis. No significant effect of the manufacturing method was observed on fatigue behavior ( p ≥ 0.05). Rigid groups exhibited no failures during testing. Conversely, the presence of a screw access hole significantly reduced fatigue behavior ( p < 0.05), with similar mean fatigue failure loads for 3D-Screw (2,286 N) and M-Screw (2,273 N) groups. The manufacturing method of the zirconia abutments (3D-printing or milling) did not influence the fatigue behavior of the restorations. However, the presence of a screw access hole in the abutments significantly reduced the fatigue behavior of the specimen.
No takes yet. Share an insight, caveat, or question.
Cocco et al. (2026) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: