Effect of surface treatments on bond strength of IPS Empress 2 and a resin-modified glass ionomer cement

Objectives: The purpose of this study was to evaluate the tensile bond strength between the IPS Empress 2 framework ceramic (Ivoclar) to the resin-modified glass ionomer cement ProTec CEM (Vivadent) under different superficial treatments. Methods: One hundred and twenty ceramic discs with 5.5 mm in diameter and 2.5 mm in thickness were made and embedded in acrylic resin. The ceramic surfaces were treated using different procedures, and ten specimens were obtained for each group: group 1 – sandblasting for 5 s with 100 mm aluminum oxide particles; group 2 – sandblasting for 5 s with 50 mm aluminum oxide particles; group 3 – etch for 20 s with 10% hydrofluoric acid (Dentsply); groups 4, 5 and 6 received the same surface treatments as the groups 1, 2 and 3 respectively, plus one coat of Scotchbond Ceramic Primer (3M) was applied. The discs were bonded into pairs with ProTec CEM. All specimens were stored in destilled water at 37o C for 24 hours and thermocycled 500 times between 5o C and 55o C. Afterwards, the specimens were submitted to tensile bond strength in a testing machine (Instron) at a crosshead speed 1.0 mm/minute until failure. The results were submitted to ANOVA and Tukey’s test (5%). Results: Group 6 (11.20 MPa) showed significantly higher bond strength than the other groups. No difference was found between group 3 (4.75 MPa), group 4 (3.61 MPa) and group 5 (4.06 MPa). Group 1 (0.51 MPa) and group 2 (0.64 MPa) showed the lowest bond strength, and there was no significant difference between them. Conclusions: Combined application of hydrofluoric acid and silane enhanced the bond strength between the ProTec CEM and the IPS Empress 2 framework ceramic.