Thermal silicatization: A new approach for bonding to zirconia ceramics

This study introduces a novel surface treatment (thermal silicatization) for bonding to zirconia ceramics. The method is based on the application of a solution containing silane, distilled water, and absolute ethanol, followed by heat treatment at 150 °C for 1 h and 600 °C for 2 h for deposition of a reactive siloxane network on the zirconia surface. The thermal silicatization was compared with traditional coupling agents for ceramic bonding (silane, zirconia primer, and/or adhesive), evaluating the shear bond strength of a dual-cured resin luting agent to yttria-stabilized zirconia. For the thermal silicatization method, two groups were tested: one group with silane applied to the ceramic (Sit) and another group with the application of silane and adhesive (SitA). Data were analyzed by ANOVA on ranks and Dunn's test (5%). The zirconia primer yielded higher bond strength compared with silane and/or adhesive. The combination of zirconia primer and adhesive generated higher bond strength than the primer alone. The group Sit showed higher bond strength than most of the groups while the bond strength of SitA had higher bond strength than all other groups. Deposition of a silicate layer on the zirconia surface was confirmed by x-ray energy dispersive spectroscopy. In conclusion, the proposed thermal silicatization method might promote the bonding of resin luting agents to dental zirconia ceramics. The proposed method is simpler and more cost-effective compared to other methods described in the literature as it could applied to the internal surface of zirconia frameworks using the same sintering protocol of the veneering ceramic.