Different Cleaning Methods for Adhesion to Saliva Contaminated Zirconia
Objectives: Saliva contamination can deteriorate bond strength to zirconia. This study assesses the effect of the cleaning protocol on shear bond strength (SBS) of a universal resin cement (3M™ RelyX™ Universal Resin Cement, RXUniv, Solventum) in self-cure mode to saliva contaminated zirconia (3M™ Lava™ Plus Zirconia, Solventum). Cleaning with 5.25% sodium hypochlorite solution (NaOCl, Speiko), Ivoclean (ICL, Ivoclar), Katana Cleaner (KCL, Kuraray) and priming with 3M™ Scotchbond™ Universal Plus Adhesive (SBUP, Solventum) were used as pretreatments. Methods: Sandblasted zirconia discs were contaminated with human saliva and divided into groups (n=6) shown in the table. ICL and KCL were applied as per manufacturers’ instructions (IFU). SBUP was applied according to IFU. Stainless steel rods (4mm diameter) were cemented onto the zirconia specimens under standardized pressure (20g/mm2) using RXUniv in self-cure mode according to IFU. Half of the specimens were stored for 24h at 36°C and 100% relative humidity, the other half was artificially aged (5.000 thermal cycles (TC), 5°C-55°C, 30sec dwell time). SBS was measured using a universal testing machine (Zwick Z010, crosshead speed: 0.75mm/min). Results: See table. The standard deviations (SD) are given in parentheses. All data per column were analyzed by ANOVA and multiple comparisons using Fisher’s LSD procedure (p<0.05). Means with the same letters are statistically the same. Conclusions: Saliva contamination deteriorates SBS of RXUniv to zirconia. All cleaning protocols yielded SBS over 20 MPa after TC. SBUP yielded the highest SBS after TC, indicating that priming with SBUP makes additional cleaning steps obsolete.