Protective role of ellagic acid in the adhesive interface after dental bleaching

To evaluate the effect of ellagic acid (EA, extracted from pomegranate) on the quality and durability of the adhesive interface after tooth whitening. Tooth fragments were divided into (n = 10/group): G1 - control (no tooth whitening and no restoration), G2 - immediate whitening and restoration and G3 - whitening followed by EA application and restoration. The samples were subjected to an in-office bleaching technique and, the amount of residual oxygen released was measured. Resin composite blocks and sticks were fabricated and bonded to the dental surfaces. After 24 h and 12 months, microtensile bond strength was evaluated by microtensile shear test. The samples were coated with carbon, and the adhesive interface examined by scanning electron microscope (SEM). Data were analyzed with two-way ANOVA followed by Tukey's test (α = 0.05). According to the bond strength test, higher values were observed in G1 > G2 < G3 at 24 h and 12 months, without statistically significant difference (p > 0.05). G1 showed the lowest level of nanoleakage, while G2 exhibited the highest. The prior application of EA in G3 resulted in intermediate nanoleakage. SEM analysis revealed a more stable adhesive interface in G3, with a lower amount of silver nitrate deposition compared to G2. EA appears to have a synergistic effect, qualitatively improving the in vitro quality of the adhesive interface by reducing oxygen in the dental structure. However, further studies are required to elucidate the mechanism of action of EA.