In vitro durability of the resin bond to feldspathic ceramics.

PURPOSE: To measure and compare shear bond strength of three different resin-based composite cements (Panavia 21, Noribond DC, and Variolink II) to two feldspathic ceramic materials (Noritake EX-3 and Ceramco) after 3 days (at baseline) and after 180 days of water storage and repeated thermocycling. METHODS: Composite cylinders were bonded with Panavia 21, Noribond DC, and Variolink II to the hydrofluoric acid (HF)-etched surfaces of either Noritake Super Porcelain EX-3 (NEX) or Ceramco (CER) following the manufacturers' directions. Subgroups of 15 specimens were stored in distilled water for either 3 days without thermocycling or 180 days with 12,000 thermal cycles. Shear bond strength was measured and compared by loading each specimen in shear to failure in an Instron testing system. Data were analyzed with a three-factor ANOVA model. Post-hoc multiple comparisons of the individual main-effect levels were performed with Tukey's HSD multiple comparison procedure (alpha = 0.05). RESULTS: Mean bond strength did not differ for the two ceramic materials. Differences in mean bond strength were found among the bonding systems and between the early and late time points. Panavia exhibited significantly lower bond strength as compared to Noribond and Variolink II for both early and late time points, with a greater difference at 180 days. For all groups, failure modes were almost exclusively cohesive in the ceramic, which indicates sufficient resin-ceramic bonds with all tested materials.