Influence of warm hydrofluoric acid etching and airborne‐particle abrasion on the bond strength of zirconia to composite resin

This study evaluated the impact of different surface treatments-airborne-particle abrasion (APA), etching with 9.5% hydrofluoric acid (HF) gel, and warm HF (WHF) etching-on the surface microstructure, topography, and shear bond strength (SBS) of 3 mol% yttria stabilized (3Y) and 5 mol% yttria stabilized (5Y) zirconia to composite resin, with and without primer application. A total of 160 zirconia specimens underwent different surface treatments, with half of them receiving primer before bonding with resin cement. x-Ray diffractometry and scanning electron microscopy (SEM) were performed. SBS was tested using a universal testing machine. Multiple linear regression was used to assess the effects of zirconia type, surface treatment, and primer on SBS, including all two- and three-way interactions. SEM analysis showed pronounced surface roughness in specimens exposed to APA and WHF surface treatments, especially for 5Y-Z. WHF treatment preserved tetragonal phase stability, while APA and HF induced phase transformations. WHF-treated specimens exhibited the highest SBS, and primer consistently enhanced SBS across all groups. WHF treatment with primer yielded the highest SBS in both zirconia types.