Can Cleansing Regimens Effectively Eliminate Saliva Contamination from Lithium Disilicate Ceramic Surface?

Abstract

This study evaluated the effect of cleaning protocols on the bond strength of resin cement to glass-ceramic. Ceramic specimens (N=120, n=12 per group) were etched with hydrofluoric acid and rinsed with water. After saliva contamination, specimens were cleaned as follows: water, 37% H3PO4, cleaning-paste (Ivoclean), or isopropanol. Non-contaminated specimens acted as the control. Resin cement was bonded to the specimens, and tested either after 24 h or x5000 thermocycling. Both the cleaning method (p=0.001) and the storage conditions (p=0.005) significantly affected the bond strength results. In dry conditions, the groups PA and IV showed no significant difference, being also similar to the non-saliva contaminated control group (p⟩0.05). In dry conditions, no significant difference was observed between the mean DW and IS being significantly lower than those of other groups (p⟨0.05). Except for the group IV, thermocycling decreased the results significantly in all groups (p⟨0.05). Predominantly mixed failure type was observed in both dry and aged conditions. SEM micrographs of ceramic surfaces after cleaning agents showed no major differences but on the specimens from the IV group, small, rounded-zirconia particles were observed. In case of saliva contamination of acid-etched glass-ceramics, mechanical cleaning can restore adhesion to the baseline situation.