The effect of different strong acids and silica‐coating on resin Ti adhesion

The presence of Si on the Ti surface is quintessential for a strong, durable silane‐based adhesion utilized in several dental applications. Silica‐coating and silanization form durable ≡Si‐O‐Si≡ bonds, which might have a positive effect on resin‐Ti adhesion. This laboratory study studied the effect of strong acids, their blends, and silica‐coating on Ti and resin‐Ti bonding. One‐hundred sixty‐eight c.p. grade 2 polished Ti samples (10 mm × 10 mm × 1 mm), out of which 96 were etched with 9% and 12%HF, a blend of 35%HCl+85%H3PO4 and a blend of 69%HNO3+35%HCl at 60°C, each for 2 min. One half was silica‐coated (Rocatec™ Plus, 110 μm SiO2‐coated‐Al2O3). Sixty Ti samples were first silica‐coated, and then, 48 of them were etched with 9%HF, 12%HF, a blend of 35%HCl+85%H3PO4, and a blend of 69%HNO3+35%HCl at 60°C for 2 min. SEM, EDX, XPS, and Ra analyses were carried out. Polished Ti samples were controls. All silanizations were carried out with a blend of 0.3 vol% 1,2‐bis‐(triethoxysilyl)ethane+1.0 vol% 3‐acryloxypropyltrimethoxysilane. Multilink™ Automix self‐adhesive resin composite cement was used in adhesion testing, and the samples were artificially aged followed by enclosed‐mold micro‐shear test on day 1 and weeks 1, 4, and 8. Failure mode analysis and statistical analysis with one‐way/two‐way ANOVA (p < 0.05) were carried out. HF etching produced the highest surface roughness. XPS analysis identified after etching with HF a variety of Ti and Si ions: Ti4+, Ti3+, Ti2+, and Ti0 and, on the other hand, Si4+, Si3+, and Si2+. A gradual decrease in adhesion strength was observed after artificial aging. Adhesive and cohesive failures were observed.