OBJECTIVETo investigate the effect of baicalein and quercetin on the enzymatic resistance of dentin matrix collagen.

METHODSBaicalein, quercetin and proanthocyanidin were dissolved in 20% dimethyl sulfoxide (DMSO) ethanol and prepared into pretreatment agents with a concentration of 50 g/L. Demineralized dentin specimens were prepared and immersed in pretreatment agents at 37 °C for 24 h, then they were digested in solution containing type?collagenase. The pretreatment agents of blank control group and negative control group were 20% DMSO ethanol, blank control group were digested in solution without collagenase. The ultimate tensile strength (UTS) and the hydroxyproline content of enzymolysis liquid in each group were measured respectively after collagenase digestion for 24 h, the dentin collagen morphology were observed under a field emission scanning electron microscopic (FE-SEM) after collagenase digestion for 12 h.

RESULTSAfter collagenase digestion for 24 h, the baicalein group had the highest UTS [(16.00±1.31) MPa], followed by proanthocyanidin group [(12.64±0.91) MPa], blank control group [(7.84±1.18) MPa], quercetin group [(3.20±1.07) MPa], and negative control group (0 MPa). Significant differences were detected among the UTS in each two group (P < 0.01). The hydroxyproline content in blank control group was the lowest [(0.40 ± 0.16) mg/L], followed by baicalein group[(2.95 ± 0.18) mg/L], proanthocyanidin group [(4.78±0.38) mg/L], quercetin group[(28.22±1.53) mg/L], and negative control group [(34.39±0.39) mg/L]. There were significant differences among the hydroxyproline contents in each group (P < 0.01). After collagenase digestion for 12 h, intact collagen network could be seen in blank control group under a FE-SEM. Collagen network in negative control group suffered nearly complete destruction and collapsed. In quercetin group, most of collagen collapsed. In proanthocyanidin group, a small portion of collagen destruction and collapse could be seen. In baicalein group, collagen network remained intact.

CONCLUSIONSThe use of baicalein and quercetin could improve enzymatic resistance of dentin matrix collagen at a concentration of 50 g/L. The effect of baicalein was better than that of proanthocyanidin while the effect of quercetin was weaker than that of proanthocyanidin.