Evaluation of shear and tensile bond strength between dentin and ceramics using dual-polymerizing resin cements

The applications of dual-polymerizing resin cements for all-ceramic restorations have considerably increased. For a successful clinical outcome, the luting agent should have high bond strength, not only to the ceramic surface, but also to the tooth surface.

The purpose of this study was to examine shear (S) and tensile (T) bond strengths between 2 all-ceramic systems and human dentin using 3 dual-polymerizing resin cements.

The buccal surfaces of 120 freshly extracted human third molars were ground flat, parallel to the long axis. Sixty specimens were prepared from each of 2 all-ceramic systems (IPS Empress 2 (E) and Cergo Pressable Ceramic (C)). Twenty specimens were luted with each of the following resin cements: Nexus 2 (N) with Self-Etch Primer, Duo-Link (D), and Variolink II (V), with their respective bonding systems. All specimens were immersed in water at 37 degrees C for 1 week, before being thermal cycled for 500 cycles in 5 degrees C and 55 degrees C water. Shear (S) and tensile (T) bond strength tests were applied to 10 specimens from each group. Fractured surfaces were inspected by scanning electron microscopy (SEM). Statistical analyses were performed using nonparametric 1-way ANOVA (Kruskal-Wallis) followed by Duncan's multiple range tests for post hoc comparison and Mann-Whitney U test for 2 ceramic systems (alpha=.05).

Significant differences were observed in shear and tensile bond strength values of the adhesive systems used (P<.05). Duo-Link showed the highest mean bond strength values, whereas Nexus 2 revealed lower shear and tensile bond strength values. Fracture modes were hybrid at the dentin interface and/or cohesive in dentin.

Cementing agents/adhesive systems may influence the bond to dental hard tissues. Dual-polymerizing activators may have a negative effect on polymerization of the bonding agent.