Effect of sulfinate salt on bonding and polymerization of adhesive to intracoronally bleached dentin

To evaluate the effect of sulfinate salt on the bond performance of a two-step self-etch adhesive to an intracoronally bleached pulpal dentin surface. Intracoronally bleached bovine teeth were treated with or without sulfinate salt (sulfinate agent (SA): Clearfil DC activator) before 2-SEA (Clearfil SE Bond 2) application, while unbleached teeth served as the control (n = 5 teeth). Microtensile bond strength (µTBS) using the bonded surface area of 1 mm² at the crosshead speed of 1 mm/min measurements after 24 h storage and thermocycles (TC), degree of conversion (DC) analyses by Raman spectroscopy (n = 3 teeth), ultrastructure of resin-dentin interface (n = 3 teeth), and intracoronally bleached pulp chamber dentin surface (n = 3 teeth) observations by scanning electron microscopy (SEM) were subsequently performed. Data were analyzed using the one-way ANOVA, Tukey's post-hoc, and paired t-test. SA significantly increased the initial µTBS to bleached pulp chamber dentin surfaces (from 34.7 ± 4.5 to 50.6 ± 5.2 MPa, p < 0.001) and maintained post-TC bond durability (49.5 ± 8.8, p = 0.58). The application of SA also significantly increased DC on bleached pulp chamber dentin (p < 0.001). Interestingly, the highest DC was found in the SA group. SEM analyses revealed no obvious alteration in surface morphology; however, numerous and longer resin tags were observed at the resin-dentin interface in the bleached group, regardless of SA application. SA could improve bond performance together and enhance the polymerization of 2-SEA to intracoronally bleached pulp chamber dentin.