Effect of Sodium Ascorbate or Alpha-Tocopherol on the Resin-Dentin Interface and Bond Strength after Endodontic Treatment and Bleaching

Abstract

The objective of this in vitro study was to assess the effects of two antioxidants (sodium ascorbate [SA] and alpha-tocopherol [AT]) on the adhesive interface and dentin bond strength immediately after bleaching with 38 % hydrogen peroxide (38HP) in endodontically-treated teeth. Two stages of experimentation were carried out. Bovine incisors were allocated into four groups (n = 10/group for each experiment): NB, non-bleached restored crowns; 38HP, bleached and immediately restored crowns; 38HP-SA, bleached crowns and SA use; and 38HP-AT, bleached crowns and AT use. Hybrid layer length in dentin (µm) and bond strength (MPa) were assessed with confocal microscopy laser and micro-shear bond strength (µSBS) test, respectively. Failure mode was determined by stereomicroscope. Data analysis was performed with analysis of variance (ANOVA) and Kruskal-Wallis, Dunn, Tukey, and Fisher-exact tests (a = 0.05). Higher values of hybrid layer length were observed similarly in the NB and 38HP-SA groups. The highest µSBS mean values were observed in the NB group (18.51 ± 1.33), whereas the SBS values for 38HP-AT (1.68 ± 0.32) were similar to the 38HP group (1.61 ± 0.51) (p > 0.05) and significantly lower than the 38HP-SA group (5.78 ± 0.71). Adhesive failures were predominant in the 38HP and 38HP-AT groups. Cohesive and mixed failures were mostly observed in the NB and 38HP-SA groups, respectively. In conclusion, AT has no immediate effect on the hybrid layer formation and µSBS of dentin. Although SA promotes an increase in hybrid layer formation, it was not reflected in the µSBS values.

The Potential of Trigona spp. Propolis as an Antioxidant Agent to Reduce Residual Peroxide after Intra-Coronal Bleaching Treatments

“…propolis 10% group was lower than that in the control group (without antioxidants) because both materials have antioxidant activity. Antioxidants are substances that neutralize free radicals by emitting their electrons, which stop the reaction that causes electron loss [35,[38][39][40][41]. The combination of Tween 80 0.2% with sodium ascorbate causes surface tension and affects the contact angle.…”