Background: Considering the increasing demand of patients for esthetic and durable restorations, zirconia, with its excellent mechanical properties, has overcome most of the limitations of all-ceramic restorations. However, bonding to zirconia is still challenging.
Objectives: This study compared the effect of 2 universal adhesives on the microshear bond strength of resin cement to zirconia after 24 h and 6 months of water storage.
Material and methods: This in vitro experimental study was performed on 56 zirconia (Prettau® Zirconia) blocks, which were randomly divided into 2 groups. The ScotchbondTM Universal single-component adhesive and the All-Bond UniversalTM 2-component adhesive were used. The PANAVIATM F 2.0 resin cement was bonded to all samples, and they were stored in distilled water for 24 h and 6 months. The microshear bond strength test was then performed, and the data was analyzed using the Kruskal-Wallis and Mann-Whitney tests.
Results: After 24 h of water storage, the All-Bond samples showed significantly higher microshear bond strength than the Scotchbond samples (p < 0.001), but at 6 months, the microshear bond strength of Scotchbond was higher. The bond strength of All-Bond decreased after 6 months (p < 0.001), but no significant change occurred in the bond strength of the Scotchbond samples over time.
Conclusions: The microshear bond strength of resin cement to zirconia depends on the type of adhesive and the duration of water storage. The Scotchbond Universal adhesive resulted in a stronger bond in the long term.
Keywords: All-Bond system; adhesives; resin cement; zirconium oxide.