Bond Strength of Resin Cement to Lithium Disilicate with Pre-treatments

Objectives: Manufacturers have introduced new surface pre-treatments that reportedly allow bonding of resin cements to glass-based ceramics with various combinations of etchant and/or coupling agents. The purpose of this study was to compare the shear bond strength of resin cement to a lithium-disilicate glass-ceramic material (e.max CAD, Ivoclar) using new surface pre-treatments.
Methods: The ceramic blocks were sectioned with a diamond saw (Isomet 5000, Buhler) into wafers and mounted in PVC pipe. The wafers were steam cleaned, dried, and the surfaces were treated with various pre-treatment solutions per manufacturer’s instructions. Five groups were created with 16 specimens each. Group 1: air abrasion with aluminum oxide and Interface (Apex Dental); Group 2: hydrofluoric acid (Ceramic Gel, Ivoclar) and Monobond Plus (Ivoclar); Group 3: Monobond Etch & Prime (Ivoclar); Group 4: air abrasion, HF acid, and Optibond XTR (Kerr); and Group 5 (control): hydrofluoric acid and silane (Bis-Silane, Bisco). Resin cement (NX3, Kerr) was placed into a mold (Ultradent) onto the surface of the specimen and light cured. The specimens were stored in water for 24 hours at 37°C and tested in shear (Instron). Data were analyzed with Kruskal-Wallis/Mann Whitney U with Bonferroni correction to evaluate the effect surface pre-treatment on the shear bond strength of resin cement to lithium disilicate (alpha=0.005).
Results: A significant difference was found based on type of surface treatment (p=0.001). The control group (hydrofluoric acid/silane) was significantly greater than the other groups which were not significantly different from each other. See table.
Conclusions:
Surface treatment of lithium-disilicate glass-ceramic with hydrofluoric acid and silane (control) resulted in significantly higher shear bond strength of the resin cement than the other pretreatment solutions.