Effect of dental silane primer activation time on resin–ceramic bonding

Abstract

The purpose of this study was to investigate the effect of activation time for the hydrolysis of dental silane primers on resin bonding to ceramic. Two commercial two-part silane primers (Bis-Silane, BS; Tokuso Ceramic Primer, TCP) were tested. Leucite-reinforced glass-ceramic (IPS Empress CAD) surfaces were used as the bonding substrates. The degree of hydrolysis of each mixed silane was observed at five specified times (immediately, 10 min, 30 min, 1 h, and 2 h after mixing) using Fourier transform infrared (FTIR) spectroscopy. Prior to resin (Duo-Link) bonding, the polished ceramic surfaces were pretreated with silanes that were activated in two different ways: an ‘in-solution’ or ‘on-surface’ activation, at the specified times. All bonded specimens were stored in water at 37 °C for 24 h prior to tensile bond strength (TBS) testing (n = 12). A one-bottle silane (Monobond-S, MS) was also tested. The FTIR analysis showed that the hydrolysis proceeded gradually for 2 h in the BS, but the initial hydrolysis halted in the TCP. When the BS was further hydrolyzed up to 2 h, the TBS values significantly increased up to 30 min (p < 0.001) with no further significant increases (p > 0.05) regardless of the activation method used. For TCP, there were no significant differences in TBS as a function of activation time (p > 0.05). The fractographic analysis of the debonded surfaces was consistent with the TBS data. In conclusion, a lengthened activation time was effective for the BS in enhancing resin bonding efficacy to the ceramic.