Problems with retention of cemented zirconia prostheses have been reported. Objective: This study assesses the efficacy of a newly developed primer (Z-Primer, Bisco) on improving the adhesion of resin cements to zirconia. Method: One conventional and two self-adhesive and resin cements were tested: A. Duo-Link (Bisco); B. RelyX Unicem Clicker (3M-ESPE); C. SmartCem2 (Dentsply). Zirconia specimens (n=60) measuring 12x10x2 mm were generated by sectioning In-Ceram YZ zirconia blocks (Vita) in the ISOMET 2000 circular saw (Buehler). All sectioned specimens were fully sintered at 15300 C for 2 hours in an 8 hour cycle. The cements were ‘bonded' to the zirconia specimens using bonding jig with Teflon inserts (2.38 mm aperture diameter). The primer was applied prior to cement application to half (n=30) of the total zirconia specimens. All 3 resin cements were mixed as suggested by the manufacturers and applied via the cylindrical opening in the bonding jig, then allowed to set for 10 min. All bonded specimens were kept in water for 36 hours then tested in shear mode in an Instron testing machine using a “flat” blade at 0.5 mm/min.
Results: Mean shear bond strengths (MPa) and SDs are presented in the table:
Cement A | Cement B | Cement C | |
Without Primer | 5.76 (2.03) | 4.01 (0.69) | 4.51 (0.84) |
With Primer | 11.72 (3.72) | 10.54 (4.68) | 8.40 (3.32) |
Two way ANOVA revealed that there was no significant difference among the materials with or without Primer. Conclusion: Using the new primer had a significant effect on increasing the bond strength to zirconia of the tested cements between 86% and 160% increase.