Effect of the flavonoid epigallocatechin-3-gallate on resin-dentin bond strength

To evaluate the effect of dentin pretreatment with epigallocatechin-3-gallate solution on the preservation of the resin/dentin interface with etch-and-rinse adhesives.

Thirty extracted human molars were prepared to expose the dentin surface and divided into 5 groups according to the pretreatment solution. Dentin surfaces were etched (35% phosphoric acid for 15 s), rinsed, and air dried. Dentin was rewetted either with distilled water, 3 different epigallocatechin-3-gallate solutions (EGCG; 0.02%, 0.1%, or 0.5% w/v), or 2% chlorhexidine digluconate solution for 60 s. Adper Single Bond 2 was applied and a subsequent 5-mm-thick resin crown was built up. Bonded teeth were longitudinally sectioned to obtain sticks with a cross-sectional area of 1.0 mm2. Half of the specimens were immediately tested, while the remaining specimens were tested after storage in 3 mMol/l sodium azide solution at 37°C for six months. The mode of fracture was examined. Bond strength values were analyzed with ANOVA and Student-Newman-Keuls tests.

After 24 h of storage, mean bond strengths of 0.5% EGCG were significantly lower than those found for the other groups (p < 0.05), except for 0.02% EGCG (p > 0.05). Resin-dentin bond strengths after 6 months were not significantly different among the experimental groups (p > 0.05). Storage in water for 6 months resulted in a significant decrease in bond strength for the water control group only (p < 0.05). The bond strengths of the experimental groups remained stable after 6 months of water storage (p > 0.05).

Pretreatment with EGCG preserved the bond of Adper Single Bond 2 to dentin after six months of storage equally well as pretreatment with chlorhexidine digluconate.