Effect of different cleaning methods on resin bond strength of contaminated monolithic zirconia

Abstract

The present study evaluated the effects of cleaning methods on resin bond strength to contaminated monolithic zirconia. A total of 180 bar-shaped monolithic zirconia specimens (12 mm × 4 mm × 1.2 mm) were abraded with aluminum oxide and divided into nine groups (n = 10). The control group (Cnt) comprised non-contaminated or cleaned monolithic zirconia specimens. Half of the remaining samples were contaminated with saliva (S) and the other half with a silicone disclosing agent (F; Fit checker). The bonding surfaces of the specimens were cleaned with water (Sw and Fw), 0.5% sodium hypochlorite (NaOCl) solution (Sh and Fh), 37% phosphoric acid gel (Sa and Fa), or plasma treatment (Sp and Fp). The bars were luted end-to-end on the bonding surfaces using a self-adhesive resin cement with a custom-made stainless-steel mold. After 72 h of water storage, the bond strength was measured using a four-point bending test. Data were analyzed using two-way ANOVA and Tukey’s test. The Cnt group showed the highest four-point bending strength (p < .05). There were no significant differences among the groups subjected to the cleaning methods, except the NaOCl groups (p > .05). These findings indicate that the cleaning protocol for saliva- or fit checker-contaminated monolithic zirconia ceramics must be taken into account to ensure zirconia–resin cement bond strength resistance. The plasma treatment that an alternative cleaning method for decontamination did not affect the bond strength between monolithic zirconia and resin cement.