Evaluation of the Microshear Bond Strength of MDP-containing and Non-MDP-containing Self-adhesive Resin Cement on Zirconia Restoration

Objectives: The purpose of this study was to measure the microshear bond strength (mu SBS) of four different self-adhesive resin cements with/without 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-containing primer to zirconium ceramics and to evaluate the effect of zirconia primers on these self-adhesive resin cements (SARCs). Methods and Materials: Zirconia blocks (20 x 20 x 8 mm(3)) were prepared and divided into eight groups (n=20). They were sandblasted (50 ium Al2O3) and treated as follows: no primer or primer (Z-Primer Plus). Four self-adhesive resin cements (MDP-containing: Permacem 2.0 [PC], Clearfil SA luting [CS]; non-MDP-containing: Rely-X U200 [RU], Maxcem Elite [ME]) were bonded to the zirconia surface. After thermocycling, a mu SBS test was performed. The failure mode was analyzed using light microscopy. Statistical analysis of mu SBS was performed using one-way analysis of variance and two-sample t-test with post hoc Tukey test. The loss rate was evaluated using the Fisher's exact test and chi(2) test with post hoc Tukey test (p<0.05). Results: Within the no primer groups, the PC and CS groups showed higher bond strength than the RU and ME groups. Comparing the mu SBS of the no primer and primer groups in the same SARCs, the RU/P group was higher than the RU group, and the ME/P group was higher than the ME group. No significant difference was observed between the PC and PC/P groups and between the CS and CS/P groups. Conclusions: Non-MDP-containing SARC showed the increased bonding value with MDP-containing primer to zirconia ceramics. The bond strength of MDP-containing SARCs was not affected significantly by the use of zirconia primer.