A dual action approach of B-type proanthocyanidins for silencing enzymatic activity and sealing natural caries-affected dentin-resin interfaces.

OBJECTIVES: This study explored the potential of dimeric and trimeric B-type proanthocyanidins (PACs) to silence dentin-associated enzymes as well as enhance sealing at the hybrid layer and in the underlying dentin of dentin-resin interfaces in both sound and natural caries-affected dentin (NCAD). METHODS: Intervention materials were chemically standardized formulations of B-type dimeric (B) and trimeric (BB) PACs from Theobroma cacao (TC), prepared using the DESIGNER approach (Depletion and Enrichment of Select Ingredients Generating Normalized Extract Resources). Human teeth were divided into two groups based on dentin substrate (sound dentin vs. NCAD) and three experimental groups (10 % TC-B primer, 10 % TC-BB primer, and HEPES primer as control). Bonding procedures utilized the etch-and-rinse technique. Specimens were prepared for interfacial in-situ zymography and interfacial micro-permeability assay and evaluated under a fluorescent microscope. Fluorescence intensities were calculated and analyzed using three-way ANOVA and post-hoc tests (alpha = 0.05). RESULTS: NCAD at the dentin-resin interface showed higher enzymatic activity when compared to sound dentin (p < 0.001). Enzymatic activity was significantly higher in sound (p < 0.001) and NCAD (p < 0.001) control groups relative to PAC-treated groups, with the latter exhibiting a substantial enzyme-silencing effect. No significant differences were observed between TC-B and T-BB groups (p = 1.0). Interfacial micro-permeability showed a similar trend, with the DESIGNER-treated groups exhibiting a profound sealing in NCAD, reaching depths up to 60 microm. CONCLUSIONS: Both B-type PAC-DESIGNERs are remarkably effective at reducing the enzymatic activity and sealing the resin-dentin interface as well as the underlying sound and NCAD dentin. CLINICAL SIGNIFICANCE: This study highlights the relevance of developing functional biomaterials capable of optimizing the adhesion of the dentin-resin interface while preserving the collagen matrix through effective enzymatic inhibition and improved sealing ability, particularly when bonding to caries-affected dentin.