Effect of prolonged application of single-step self-etching primer and hydrofluoric acid on the surface roughness and shear bond strength of CAD/CAM materials

This in vitro study aimed to assess the influence of different concentrations and durations of hydrofluoric acid (HF) and Monobond Etch & Prime (MEP) etching on the surface roughness (R-a) of different CAD/CAM materials and on the shear bond strength (SBS) of a self-adhesive resin bonded to the materials. Seventy specimens of hybrid ceramic, leucite-based glass-ceramic, lithium disilicate glass-ceramic, and zirconia-reinforced lithium silicate glass-ceramic were prepared and divided into seven groups according to the surface treatments: Control (C); MEP etching for 60 (MEP60) and 120 (MEP120) s; 5% HF etching for 60 (HF-5%(60)) and 120 (HF-5%(120)) s; 9.5% HF etching for 60 (HF-9.5%(60)) and 120 (HF-9.5%(120)) s. The R-a was measured using a 3D profilometer. All groups were treated with a universal primer except for the C, MEP60, and MEP120 groups. A self-adhesive resin cement was bonded to all specimens, and the bond strengths were measured using a universal testing machine. All surface treatments increased both R-a and SBS values compared to the control in each material. Neither the duration of surface treatments nor the HF acid concentrations had a statistically significant effect on SBS. Within the limitations of this experimental study, it can be concluded that Monobond Etch & Prime may be a preferable method to achieve high bond strength values.