Bonding values of two contemporary ceramic inlay materials to dentin following simulated aging

Abstract

Purpose: To compare the push-out bond strength of feldspar and zirconia-based ceramic inlays bonded to dentin with different resin cements following simulated aging.

Materials and methods: Occlusal cavities in 80 extracted molars were restored in 2 groups (n=40) with CAD/CAM feldspar (Vitablocs Trilux forte) (FP) and zirconia-based (Ceramill Zi) (ZR) ceramic inlays. The fabricated inlays were luted in 2 subgroups (n=20) with either etch-and-bond (RelyX Ultimate Clicker) (EB) or self-adhesive (RelyX Unicem Aplicap) (SA) resin cement. Ten inlays in each subgroup were subjected to 3,500 thermal cycles and 24,000 loading cycles, while the other 10 served as control. Horizontal 3 mm thick specimens were cut out of the restored teeth for push out bond strength testing. Bond strength data were statistically analyzed using 1-way ANOVA and Tukey's comparisons at α=.05. The mode of ceramic-cement-dentin bond failure for each specimen was also assessed.

Results: No statistically significant differences were noticed between FP and ZR bond strength to dentin in all subgroups (ANOVA, P=.05113). No differences were noticed between EB and SA (Tukey's, P>.05) bonded to either type of ceramics. Both adhesive and mixed modes of bond failure were dominant for non-aged inlays. Simulated aging had no significant effect on bond strength values (Tukey's, P>.05) of all ceramic-cement combinations although the adhesive mode of bond failure became more common (60-80%) in aged inlays.

Conclusion: The suggested cement-ceramic combinations offer comparable bonding performance to dentin substrate either before or after simulated aging that seems to have no adverse effect on the achieved bond.

Keywords: Bonding; Ceramics; Dentin; Inlays; Resin cement.

Fig. 1. Preparation of occlusal cavities (The dotted line indicates the standardized leveling of cavity depth).

Fig. 2. Calculation of the bonded surface area.

Fig. 3. Testing push-out bond strength (A) Stressing test specimens on compression, (B) Flat-ended indenter and (C) test specimen.

Fig. 4. Recorded modes of bond failure. (A) Mixed failure (white arrow indicates dentin substrate and the black arrow indicates cement material), (B) Adhesive bond failure at dentin-cement interface (white arrow indicates dentin substrate), (C) Adhesive failure at ceramic-cement interface (black arrow indicates cement material).