Evaluation of the microshear bond strength of resin cement to zirconia treated by different nanomaterials using the dip coating technique

Abstract

Aim: Using a dip-coating technique, this study evaluated the microshear bond strength of resin cement to zirconia surfaces coated with nanosilica and nanoalumina. Methods: Zirconia blocks (n = 56) were categorized into seven groups based on surface treatment: untreated (control), tribochemical silica coating (positive control), dip coating with pure nanosilica, pure nanoalumina, and nanosilica-nanoalumina mixtures at 75:25, 50:50, and 25:75 volume ratios. The coated surfaces underwent characterization using a Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD), and Atomic Force Microscopy (AFM). Resin cylinders were cemented onto the treated zirconia surfaces, and microshear bond strength testing was performed. Differences in bond strength between groups were analyzed using One-way ANOVA and Tukey’s post-hoc test (p < 0.05). Results: SEM revealed that nanosilica coatings formed island-like agglomerations, nanosilica-nanoalumina produced porous layers, and nanoalumina formed a dense cover layer. XRD detected only the tetragonal phase in coated zirconia, indicating no phase transformation compared to tribochemical silica coating. Microshear bond strength was higher for all coating groups than for controls (p < 0.05). The 75:25 nanosilica-nanoalumina demonstrated greater bond strength than other ratios. Conclusion: Dip-coating proved effective in enhancing resin-zirconia bonding without causing surface damage. Among the various ratios, the 75:25 nanosilica-nanoalumina mixture exhibited optimal bond strength.