Microtensile Bond Strength of Resin-bonded Hightranslucency Zirconia Using Different Surface Treatments

Purpose: To evaluate the effect of a novel surface treatment intended to improve bond strength to high-translucency zirconia. Materials and Methods: Fully sintered high-translucency zirconia disks (Incoris TZI) were divided into four groups according to the surface treatment received: modified fusion sputtering technique, selective infiltration etching, low pressure particle abrasion using 30-μm alumina particles, while 50-μm particle abrasion served as control. Surface roughness was evaluated quantitatively using a contact profilometer. The disks were bonded to pre-aged composite resin disks using a light-polymerized adhesive resin (RelyX ultimate). The bilayered disks were sectioned into microbars and zirconia-resin bond strength was evaluated using the microtensile bond strength test (MTBS). The test was repeated after 3 months of water storage (37°C). Scanning electron microscopic examination of the zirconia resin interface was performed at different magnifications. A repeated measures ANOVA and Bonferroni post-hoc test were used to analyze the data (n = 20, α = 0.05). Results: One-way ANOVA revealed significant differences in average surface roughness (Ra) between the tested groups (p 0.001). The highest Ra value was recorded for fusion sputtering (12.23 ± 0.11 μm), followed by 50-μm particle abrasion (6.400 ± 0.887), then low pressure 30-μm particle abrasion (2.4 ± 0.15 μm), while the lowest surface roughness was recorded for the selective infiltration group (0.368 ± 0.04 μm). Modified fusion sputtering and selective infiltration etching produced significantly higher MTBS values at each of the tested intervals (p 0.001) compared to particle abrasion using different particle sizes. Water storage resulted in reduction in the bond strength of 30-μm abraded specimens, which was attributed to structural defects observed at the zirconia/ resin interface. Scanning electron microscopic examination revealed a nanoporous surface characteristic of selective etching surface treatment, and modified fusion sputtering resulted in the creation of surface-fused microbeads. Conclusion: Within the limitations of this study, selective infiltration etching and modified fusion sputtering techniques established a strong, stable, durable bond to high-translucency zirconia. Keywords: high-translucency zirconia, microtensile bond, surface treatment, selective etching, fusion sputtering