Effect of various primers on the long-term bond strength to zirconia

Abstract

Objective To compare the effects of 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP)- and silane-based primers with those of MDP-based primers on zirconia-resin bonding via multiple levels of aging. Methods Zirconia blocks were divided into 4 groups (n = 21) according to the primer used: MDP-based Z-Prime Plus (ZP), silane-based Monobond-S (MS), MDP- and silane-based Clearfil Ceramic Primer (CCP) and no primer (Blank). After pretreatment with or without the primers followed by bonding with cement Duo-Link, each group was subdivided into 3 subgroups (n = 7) according to aging level: 24 hours of water storage at 37 ℃ (24 h), 30 days of water storage at 37 ℃(30 d), and 30 d plus 3 000 thermal cycles (30 d/TC). After aging, shear bond strength (SBS) tests and failure mode analyses were conducted. Results ZP, MS and CCP groups had greater SBSs than did the BLANK group (P<0.01). From 24 h to 30 d, the shear bond strength significantly increased (P<0.05); however, the shear bond strength decreased significantly from 30 d to 30 d/TC (P<0.01) and fell below baseline (30 d/TC vs. 24 h, P<0.01). Within the primer groups, CCP exhibited a higher SBS than ZP and MS at each aging level (P<0.001). The bonding strength of ZP was greater than that of MS at 30 d (P = 0.029) but lower than that of MS at 30 d/TC (P = 0.037). From 30 d to 30 d/TC, the percent decrease in the bonding strength of ZP was significantly greater than that of MS (82.43% vs. 64.90%). Conclusion MDP-based primers function better for zirconia-resin bonding when they contain silane coupling agents.

Keywords

• zirconia|ceramics|bonding|primer|z-prime plus|clearfil ceramic primer|cold and heat cycle aging