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 (Ra ) 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 Ra 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 Ra 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.

Effect of monolithic CAD-CAM ceramic thickness on resin cement polymerization: An in-vitro study.

PURPOSE: To evaluate the effect of different thicknesses of CAD-CAM ceramic sections on the polymerization of two different resin cements. METHODS: Three CAD-CAM all-ceramic restorative materials were sectioned with four different thicknesses. A total of 240 resin cement specimens were prepared from light cured and dual cure resin cements and absorption peaks were recorded. 10 samples of each resin cement were examined before and after polymerization and served as the control group. Data were analyzed using one-way ANOVA, independent t- and Tukey HSD tests (P< 0.05). RESULTS: Control group showed the highest DOC values while samples cured under Vita Enamic section with a thickness of 2 mm presented the lowest values (P< 0.05). Polymerization performed under sections of 0.5 and 1 mm thicknesses provided statistically higher values. Dual cured resin cement samples showed higher DOC values compared to light cured resin cement samples. IPS Empress CAD sections with 0.5 and 1 mm thickness exhibited statistically higher values than other ceramics of the same thickness for light cured resin cement samples. A significant difference was observed between IPS Empress CAD and Vita Enamic while comparing ceramic sections of the same thickness (P< 0.05). There was no difference for sections of 1.5 and 2 mm (P>> 0.05). CLINICAL SIGNIFICANCE: Thickness of the restorative material for an indirect restoration is a key element to determine the type of resin cement.