Dimeric Proanthocyanidins on the Stability of Dentin and Adhesive Biointerfaces

Abstract

A dentin biomodification strategy with selective proanthocyanidin (PAC)–enriched extracts reinforces dentin and dentin-resin interfaces. Enrichment of the extracts according to the degree of polymerization allows exploration of bioactive principles of PACs and structure-activity relationships. This study investigated the sustained dentin matrix biomodification and dentin-resin bioadhesion of 2 fractions consisting exclusively of B-type PAC dimers with or without a single galloyl motif (specifically, DIMERG and DIMERNG) and their precursor material, enriched grape seed extract (e-GSE; Vitis vinifera). The biomodification potential was determined by long-term evaluation of the apparent modulus of elasticity and collagen solubility (hydroxyproline release). Chemical characterization of the dentin matrix was performed by attenuated total reflectance–Fourier-transform infrared spectroscopy. The bioadhesive properties were assessed by a microtensile bond strength test at different time points, and macro-hybrid layers were produced to verify the degree of conversion of the adhesive resin. Fractions consisting of DIMERG, DIMERNG, and their precursor, e-GSE, increased the modulus of elasticity at all time points and reduced collagen degradation. Specimens treated with DIMERNG remained stable throughout 12 mo of storage, whereas a significant drop in the modulus of elasticity was observed for the DIMERG and e-GSE groups at 6 mo. The fractions and precursor did not affect the degree of resin conversion at the hybrid layer. Changes in infrared resonances corresponding to collagen cross-links in the dentin matrix occurred for all treatments. Higher bond strength was observed for dentin treated with e-GSE as compared with DIMERG and DIMERNG; all biointerfaces remained stable after 12 mo. Nongalloylated PACs mediate stable dentin biomodification, which includes protective activity against collagen degradation and reinforcement of the anchoring dentin matrix. Collectively, PACs with a higher degree of oligomerization offer a robust bioadhesion between the hydrophilic dentin matrix and the hydrophobic adhesive.

Galloylated proanthocyanidins in dentin matrix exhibit biocompatibility and induce differentiation in dental stem cells

“…eGSE, DIMER G and DIMER NG have previously shown the ability to improve stability of dentin-resin biointerfaces. 10 In this study, DIMER G and DIMER NG did not elicit harmful effects on DPSCs which supports their suitability in dental applications. Interestingly, compared with non-galloylated monomers and PACs, galloyl moieties also enhanced resistance to enzymatic degradation and improvement of biomechanical properties.…”

“…This data supports the use of dimeric PACs as a safe biomaterial, with galloylated dimeric PACs exhibiting potential benefits to odontoblasts supporting dentin regeneration. dentin matrix and stabilize dentin-resin interfaces, 10 whereby galloylation changes the ability of PACs to co-polymerize with components of the dentin ECM. 2 For example, we have previously demonstrated that galloyl moieties enhance the dentin biomodification ability of catechins, 3,10,11 the monomeric building blocks of PACs.…”

“…Recently, the ability of a primer containing dimeric B-type PACs from GSE was shown to enhance the biomechanical properties of the dentin matrix and stabilize dentin-resin interfaces, 10 whereby galloylation changes the ability of PACs to co-polymerize with components of the dentin ECM. 2 For example, we have previously demonstrated that galloyl moieties enhance the dentin biomodification ability of catechins, 3,10,11 the monomeric building blocks of PACs. However, the biocompatibility of these compounds with living pulp cells is unknown, as is the influence of galloylation on biocompatibility.…”

Harnessing biomolecules for bioinspired dental biomaterials

“…404 Application of proanthocyanidins on dentin has been shown to reduce dentin permeability, 405 increase tensile (among many) mechanical properties, 406 reduce degradation due to water and enzymes, 407 and increase bonding. 408 Other work has shown that proanthocyanidins may help protect dental pulp from restoration-associated cytotoxicity. 409 Recent clinical trials have suggested limitations of proanthocyanidin application to extend restoration lifespans.…”

Paradoxical effects of galloyl motifs in the interactions of proanthocyanidins with collagen‐rich dentin

“…Long‐term findings revealed that PACs extracts with the most favorable biomodification potency may not necessarily sustain the elicited bioactivity over an extended time 5,10,11 . Particularly, PACs extracts containing galloyl groups (flavanol 3‐ O ‐gallic acid esters) are among those PAC species that exhibit a notable reduction of their strong initial bioactivities over time, before reaching a plateau 11,12 . Therefore, the study premise is that galloyl functionalities are major contributors to a relatively unstable form of PAC‐dentin biomodification.…”