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This study evaluated the influence of an alternative surface treatment on the microshear bond strength (μsbs) of zirconia-based ceramic. Thirty-five zirconia disks were assigned to five groups according to the following treatments: Control (CO), glass and silane were not applied to the zirconia surface; G1, air blasted with 100μm glass beads + glaze + silane; G2, a gel containing 15% (by weight) glass beads applied to the ceramic surface + glaze + silane; G3, a gel containing 25% (by weight) glass beads applied to the ceramic surface + glaze + silane; and G4, a gel containing 50% (by weight) glass beads applied to the ceramic surface + glaze + silane. The specimens were built up using RelyX ARC ® , according to the manufacturer's recommendations, and inserted in an elastomeric mold with an inner diameter of 0.8 mm. The μsbs test was performed using a testing machine at a crosshead speed of 0.5 mm/min. ANOVA and Tukey's test (p < 0.05) were applied to the bond strength values (in MPa). CO (15.6 ± 4.1) showed the lowest μsbs value. There were no statistical differences between the G1 (24.9 ± 7.4), G2 (24.9 ± 2.3), G3 (35.0 ± 10.3) and G4 (35.3 ± 6.0) experimental groups. Those groups submitted to surface treatments with higher concentrations of glass showed a lower frequency of adhesive failures. In conclusion, the glass application improved the interaction between the ceramic and the luting cement.

Objective To assess the influence of hydrophilicity of reactive nanogels on the mechanical performance of dental adhesives and microtensile bond strength (μTBS) to dentin after 24 h or 3 months of aging. Methods A series of three nanogels were synthesized: NG1—IBMA/UDMA; NG2—HEMA/BisGMA; NG3—HEMA/TE-EGDMA. The nanogels were dispersed in solvent, HEMA or BisGMA/HEMA. The degree of conversion (DC) of the materials was measured and the flexural modulus of these polymers was evaluated in dry or wet conditions. For μTBS analysis, a model adhesive was used without nanogel (control) or with the incorporation of nanogels. μTBS was evaluated after storage in distilled water for 24h or 3 months. The analysis of the fracture was performed after μTBS testing. Data were analyzed using ANOVA and Tukey’s test (α = 0.05). Results Water significantly increased the modulus of NG1 and NG2 dispersed in solvent, while significantly decreased the stiffness of NG3. All polymers dispersed in HEMA and Bis-GMA/HEMA had significantly lower modulus when stored in water. NG2 showed the highest DC in solvent and BisGMA/HEMA. In HEMA, NG1 and NG3 produced the highest DC. After three months, NG2 showed the best μTBS. The μTBS of NG2-containing adhesive resin significantly increased after 3 months, while storage had no effect in the control group, NG1 and NG3. Significance The more hydrophobic IBMA/UDMA nanogel showed higher bulk material mechanical property results, but the best dentin bond strength values, and notably strength values that improved upon storage, were obtained with the amphiphilic nanogel based on BisGMA/HEMA.

The innovative method to simulate pulpal pressure behaved similarly to the classic one and could be used as an alternative. The HEMA-free one-step and the two-step self-etch adhesives had acceptable resistance against pulpal pressure, unlike the HEMA-rich adhesive.