Effect of Zircos-E etching as surface treatment on monotonic and fatigue strength of a 4YSZ.

Abstract

This study evaluated the effect of Zircos-E etching as a surface treatment on the monotonic and fatigue strength of 4 mol% yttria-stabilized zirconia (4YSZ), with and without resin cement. Disc-shaped specimens (n = 15 per group; Ø = 15 mm × 1.2 mm) were assigned to four surface conditions: control (no treatment), alumina air abrasion (AirAbr), Zircos-E etching for 30 min (ZE30), and for 2 h (ZE2). Each group was tested both with and without resin cement (Multilink N). Monotonic strength was measured using a biaxial flexural test, while fatigue strength was assessed via stepwise loading, beginning at 130 MPa with 30 MPa increments every 10,000 cycles. Surface roughness, topography, and fractography were also analyzed. Statistical analysis showed that surface treatment significantly influenced fatigue strength (p < 0.001), especially in cemented groups. After cementation, the AirAbr (768.2 ± 174.1 MPa) and ZE2 (757.4 ± 155.1 MPa) groups exhibited the highest fatigue strength, while the untreated control group had the lowest values (519.4 ± 88.7 MPa). Monotonic strength was significantly improved by air abrasion (894.2 ± 153.1 MPa), while Zircos-E produced intermediate results. In terms of surface roughness, ZE2 presented the highest Ra (0.99 ± 0.13 μm) and Rz values, significantly higher than the control (Ra = 0.45 ± 0.07 μm), confirming enhanced micro-retentive topography. Zircos-E etching, particularly for 2 h, effectively improved fatigue performance and roughness of 4YSZ ceramics, with outcomes comparable to conventional air abrasion. CLINICAL SIGNIFICANCE: Zircos-E treatment may offer a promising surface conditioning strategy for zirconia restorations, providing improved mechanical performance, particularly when combined with resin cement.