Effects of Cleaning Protocols on Resin Bond Strength to Saliva-Contaminated Monolithic Zirconia.

Purpose: Considering the significant weakening of the bonding of resin cements to saliva-contaminated zirconia restorations, this study aimed to investigate the effect of various surface treatment methods on the bonding of self-adhesive resin cement to zirconia after various cleansing methods.

Material and methods: A total of 105 monolithic zirconia specimens were cut from pre-sintered blocks using a water-cooled precision diamond saw. Specimens were kept in the artificial saliva except for the control group. The specimens were then cleaned using one of the following methods: 1. Air-water spray, 2. Isopropyl Alcohol, 3. Pumice, 4. Universal cleaning agent (Ivoclean), 5. Sandblasting, 6. Sandblasting + Ivoclean. Specimens were bonded to self-adhesive resin cement. Specimens were thermocycled for 5,000 cycles after cementation and tested in shear mode (1 mm/min). Images were obtained using a stereomicroscope, scanning electron microscope, and energy-dispersive spectroscopy. Data were analyzed using ANOVA, and multiple comparisons were performed with the Duncan test (α = 0.05).

Results: The mean shear bond strength values were as follows in descending order: Sandblasting + Ivoclean (9.3 MPa) > sandblasting (8.59 MPa) > Ivoclean (7.21 MPa) > Pumice (4.82 MPa) > Air-water spray (4.15 MPa) > Control (3.65 MPa) > Isopropyl alcohol (3.04 MPa). Significant difference was observed between sandblasting and Ivoclean groups, and between sandblasting and sandblasting + Ivoclean groups (P 0.05). A significant difference was also found between the Ivoclean and sandblasting + Ivoclean groups. The groups treated with sandblasting + Ivoclean, sandblasting, and Ivoclean showed a significant difference compared to all other surface treatment groups. There was no significant difference in shear bond strength among the control, air-water, alcohol, and pumice groups (P > 0.05). Sandblasting, Ivoclean, and Ivo-clean after sandblasting applications were found to deliver significantly higher (P 0.05) adhesion compared with air-water, pumice, and alcohol applications.

Conclusions: Subsequent applications of Ivoclean after sandblasting established a stronger bond between self-adhesive resin cement and monolithic zirconia than other cleaning methods tested.

Clinical implications: Following airborne particle abrasion, intaglio surfaces of zirconia restorations should best be cleaned using Ivoclean.