Influence of Cleaning Methods on the Bond Strength of Resin Cement to Saliva-Contaminated Lithium Disilicate Ceramic

The aim of the present study was to examine the influence of different cleaning methods on the bond strength of resin cement to saliva-contaminated lithium disilicate ceramic. Lithium disilicate ceramic specimens (n = 8/group) were etched with 5% hydrofluoric acid (HF) to comprise the control group. After or before saliva contamination, specimens were cleaned with one of five methods: rinsing with water-spray (WS), K etchant GEL (PA), Ivoclean (IC), AD Gel (ADG), or application of a silane coupling agent before immersion in saliva (SCA). Stainless steel rods were bonded to the ceramic with resin cement. The tensile bond strength was measured after 24 h (TC0) and after thermal cycling at 4–60 °C (TC20000). Specimen surfaces were also evaluated using X-ray photoelectron spectroscopy. Data were statistically analyzed using two-way ANOVA and Tukey tests (α = 0.05). Both the cleaning method (p = 0.0001) and storage condition (p = 0.0001) significantly affected the bond strength results. Before or after TCs, no significant differences in bond strength were observed between the control group and the other cleaning groups except for the WS group, which had a significantly lower bond strength than did the PA, IC, ADG, or SCA groups (p < 0.05). The level of nitrogen in the ADG group was almost equal to that in the control group. WS cleaning did not restore the bond strength of resin cement to saliva-contaminated lithium disilicate ceramic etched with HF, while PA, IC, ADG, and SCA all benefited. Lithium disilicate ceramic restorations etched with HF should to be cleaned with ADG after saliva contamination.