Bonding to Zirconia Using a New Surface Treatment

PURPOSE: Selective infiltration etching (SIE) is a newly developed surface treatment used to modify the surface of zirconia-based materials, rendering them ready for bonding to resin cements. The aim of this study was to evaluate the zirconia/resin bond strength and durability using the proposed technique. MATERIALS AND METHODS: Fifty-four zirconia discs were fabricated and divided into three groups (n = 18) according to their surface treatment: as-sintered surface (control group), airborne-particle abrasion (50-mum aluminum oxide), and SIE group. The zirconia discs were bonded to preaged composite resin discs using a light-polymerized adhesive resin (Panavia F 2.0). The zirconia/resin bond strength was evaluated using microtensile bond strength test (MTBS), and the test was repeated after each of the following intervals of accelerated artificial aging (AA): thermocycling (10,000 cycles between 5 and 55 degrees C), 4 weeks of water storage (37 degrees C), and finally 26 weeks of water storage (37 degrees C). Silver nitrate nanoleakage analysis was used to assess the quality of zirconia/resin interface. A repeated measures ANOVA and Bonferroni post hoc test were used to analyze the data (n = 18, alpha= 0.05) RESULTS: There were significant differences in the MTBS values between the three test groups at each of the test intervals (p < 0.001). AA resulted in reduction in the bond strength of the as-sintered and the particle-abraded groups (5.9 MPa and 27.4, MPa, respectively). Reduction in the bond strength of these groups was explained by the observed nanoleakage across the zirconia/resin interface. The bond strength of the SIE specimens was stable after completion of AA (51.9 MPa), which also demonstrated a good seal against silver nitrate penetration across the zirconia/resin interface. CONCLUSION: SIE established a strong, stable, and durable bond to zirconia substrates. Conservative resin-bonded zirconia restorations are now possible using this new technique.