pH of Adhesives: Bonding of Resin Cement to a Ceramic

Objective: to evaluate the effect of the different pH values of adhesives on the bond strength of resin cement (CR) (photo/chemical/dual-cure) to a feldspathic ceramic. Methods: Ceramic blocks (90) (VM7-VITA) (5 x 5 x 5 mm) were made according to the manufacturer's recommendations. A ceramic surface were conditioned with hydrofluoric acid (HF) (9.6%) (1 min) (Dentsplyl) + silane (Porcelain Primer, Bisco). Three adhesives (Scotchbond Multi-Purpose Plus Adhesive (SBMP 3M ESPE; pH = 5.6); Single Bond (SB 3M, ESPE; pH = 3.4); Prime & Bond NT (PBNT, DENTSPLY; pH = 1.7)) were applied. After, three CR with different cure were applied: Photo (Variolink II base, Ivoclar Vivadent); Dual (Variolink II base + catalyst, Ivoclar Vivadent); Chemical (C&B, Bisco). The specimens were sectioned resulting in 6 specimens (sp) per ceramic block (adhesive area: ± 1 mm²). Nine experimental groups were obtained (n=10): G1 SBMP + CR Photo, G2 SBMP + CR Dual, G3 SBMP + CR Chemical, G4 SB + CR Photo, G5 SB + CR Dual, G6 SB + CR Chemical, G7 PBNT + CR Photo, G8 PBNT + CR Dual, G9 PBNT + CR Chemical. The specimens were stored (37°C/24h) and then sectioned and submitted to the tensile bond strength test in a universal testing machine (cross-head speed: 1 mm/min). Data were statistically analyzed (ANOVA and Tukey's test, 0.05). Results: The bond strengths (MPa) of G1 (17.03 ± 6.9a), G2 (14.90 ± 6.9a,b), G3 (17.91 ± 6.8a), G4 (12.33 ± 5.2b,c,d), G5 (14.41 ± 7.2a,b,c), G6 (14.24 ± 5.1a,b,c), G7 (11.03 ± 5.2c,d), G8 (12.64 ± 4.9b,c,d), G9 (9.42 ± 6.8d). Conclusion: It was direct relation between pH value of adhesives and bond strength with CR chemical cured. The highest values of bond strength allowed the highest pH of the adhesives independent of the type cure of the CR.