Effect of Sodium Ascorbate on Resin Bonding to Sodium Perborate–bleached Dentin

Abstract

SUMMARY This was an in vitro study to evaluate the effect of sodium ascorbate on the microshear bond strength (MSBS) of resin composite to sodium perborate-bleached dentin. Molar dentin sections were divided into six groups: 1) control, 2) sodium perborate (SP) bleach and immediate bonding, 3) SP and 30 second sodium ascorbate (SA); 4) SP and 1 minute SA; 5) SP and 2 minute SA; and 6) SP and 7 day delay before bonding. They were further divided into two-step self-etching (Clearfil SE Bond) or all-in-one self-etching (Xeno IV) adhesive systems. Resin composite microtubes were bonded according to dentin location-center, pulp horn, and peripheral positions-and an MSBS test was carried out. Failure mode was determined using light microscopy and scanning electron microscopy. There were no significant differences between the treatment types/groups. MSBSs were significantly higher for two-step self-etching adhesive compared with all-in-one self-etching adhesive (p=0.028). For the all-in-one adhesive, MSBSs at the center and pulp horn positions were significantly lower than the peripheral positions (p<0.001). All-in-one groups had significantly more adhesive failures than two-step adhesive groups (p=0.015). The odds of adhesive failure were higher at the pulp horn position than the peripheral position (p=0.004). Sodium perborate bleaching of dentin had no effect on MSBS or mode of failure for either two-step or all-in-one self-etching adhesives; therefore, the effect of sodium ascorbate was negligible. The two-step adhesive groups demonstrated the highest MSBS, and the all-in-one groups, when bonded to center and pulp horn dentin, exhibited the lowest MSBS.