Effects of Various Cleansing Methods on Bond Strength of Contaminated Zirconia, Lithium Disilicate and Metals

PURPOSE: The purpose of this study is to investigate the effects of various cleansing methods on bond strengths of contaminated zirconia, lithium disilicate, and metal. MATERIALS AND METHODS: Zirconia and titanium metal blocks were air-abraded with alumina sand (50μm) for 20 seconds, and lithium disilicate blocks were etched with hydrofluoric acid etchants for 20 seconds. The specimens were rinsed with water, dried, and contaminated with saliva, blood or oil for 1 minutes. Ten groups of each restoration material were studied: 1) no contamination (NC); 2-4) saliva contamination followed by ultrasonic cleaning in water (SW), ultrasonic cleaning in ethanol (SE), or cleaning with a cleaning agent DashClean (SD); 5-7) blood contamination followed by ultrasonic cleaning in water (BW), ultrasonic cleaning in ethanol (BE), or cleaning with DashClean (BD); 8-10) oil contamination followed by ultrasonic cleaning in water (OW), ultrasonic cleaning in ethanol (OE), or cleaning with DashClean (OD). Zirconia and metal groups were treated with an MDP-containing primer, and lithium disilicate group was treated with a silane primer. All groups were subjected to shear bond strength test. RESULTS: For zirconia bonding, SW, SE, BW, BE, OW and OE were significantly lower than NC, SD, BD, or OD (p<0.05); for lithium disilicate bonding, SW and OW were significantly lower than NC, SD, BD, or OD (p<0.05); for metal bonding, SW, SE, OW and OE were significantly lower than NC, SD, BD, or OD (p<0.05). CONCLUSION: Within the limitations of this in vitro study, ultrasonic cleaning in water or ethanol were not able to remove the negative effects on resin bond strength of contaminated zirconia, lithium disilicate or metal, while the cleaning agent DashClean was effective in removing saliva, blood, and oil contamination and enhancing the resin bond strength.