One-year Durability of MDP-containing Adhesive Resin Cements Bonding to Zirconia

Objectives: Ultra-translucent multi-layered zirconia is gaining acceptance for adhesively cemented monolithic restorations in the esthetic zone. Adhesives containing 10-Methacryloyloxydecyl dihydrogen phosphate (MDP) have shown successful bonding to alumina-blasted zirconia. The objective of this study was to evaluate the duability of micro-shear bond strength (MSBS) of different adhesive resin cement systems to zirconia.
Methods: Standard disc specimens of zirconia (Katana UTML, Kuraray Noritake Dental) were milled, sintered, polished and alumina-blasted at 0.3 MPa. Three adhesive resin cements (Kuraray Noritake Dental), Panavia V5 with Clearfil Ceramic Primer (V5); Panavia SA Cement Plus (SA Plus); and SA Plus with Clearfil Universal Bond Quick (UBQ) in light-curing mode were evaluated. MSBS of composite resin cylinders 0.79mm in diameter and 2mm in height was evaluated by the wire-loop technique after 24-hrs (baseline) and 1-yr storage in deionized water at 37°C using a compact testing machine (Bisco). The results were subjected to Repeated Measures ANOVA test at significance level of 0.05.
Results: Resin cement, storage time and their interaction had significant effect on MSBS (p<0.05). There was no significant difference among the groups at the baseline; however, after 1-yr there was a significant difference between SA-Plus and other groups. The most stable bonding performance resulted from SA Plus; while there was a significant reduction in bond strength after 1-yr for SA Plus+UBQ and V5 (p<0.05).
Conclusions: Hydrolytic degradation of the interface in the aggressive in vitro storage environment over 1-yr significantly reduced the bond strength in this laboratory study, except for the MDP-containing self-adhesive resin cement without any primer or bonding application on the translucent zirconia substrate, resulting in the most stable bonding.