Collagen biomodification and bond stability in dentin pretreated with natural galloylated agents

Abstract

This in vitro study evaluated the effect of biomodifying agents - 0.1 % epigallocatechin-3-gallate (EGCG), 1 % tannic acid (TAN), 6.5 % grape seed extract (GSE), and distilled water (DW) - used as aqueous dentin pretreatments on dentin collagen and on the adhesive performance of composite resin restorations. Dentin specimens were pretreated actively for 60 s with solutions prepared in a 100 % distilled water solvent. The outcomes assessed were modulus of elasticity (ME) by the three-point bending test (n = 15); mass variation (MV%) (n = 15); and dentin bond strength to composite resin (n = 8), assessed via microtensile bond strength to composite resin along with fracture pattern analysis. Qualitative evaluations included Fourier-transform infrared spectroscopy (FTIR) (n = 3) and micropermeability testing (n = 3). Statistical analysis was conducted using two-way ANOVA followed by Tukey's post hoc test (p < 0.05). TAN group presented the highest ME values. For MV%, both EGCG and TAN exhibited significant mass gain compared to the other groups (p < 0.05), which remained stable after degradation. Regarding bond strength, only TAN and GSE preserved interface stability after six months, consistent with the hybrid layer quality observed in the micropermeability analysis. Failure modes differed significantly over time in the DW (p = 0.025) and EGCG (p = 0.002) groups. FTIR revealed stronger amide I and II peaks for TAN and GSE. It can be concluded that the tested natural agents are effective in collagen biomodification; however, only TAN and GSE sustained long-term resin–dentin bond stability.