Physicochemical properties, antibacterial and antiproteolytic activities, and effect on stabilization of adhesive interfaces in caries-affected dentin of flavonoid-modified adhesive systems

Abstract

Caries-affected dentin (CAD) is a prevalent clinical substrate, reflecting the need to explore the management and stabilization of adhesive procedures in this context. Cross-linking agents favor the mechanical properties of collagen and inhibit the action of endogenous proteases, preserving its stability. CAD treatment with flavonoids prior to adhesive procedures has proved to be an adequate strategy to improve the longevity of adhesive interfaces. The incorporation of flavonoids into adhesive systems could reduce technical sensitivity and clinical steps, also presenting a local antibacterial effect, which could act on the deleterious effects of marginal infiltration by microorganisms. Thus, this study aims to investigate the effects of incorporating the flavonoids proanthocyanidins-rich grape seed extract (GSE) or quercetin (QU) in adhesive systems (self-etching and universal) on their physicochemical properties, antibacterial and antiproteolytic activities, and effect on the stabilization of adhesive interfaces produced in CAD. This research project consists of 3 sequential phases. In the first phase, we will screen different concentrations of the flavonoids GSE and QU incorporated into self-etching and universal adhesive systems to evaluate their physical-chemical and mechanical properties. Based on the results of this initial phase, the most appropriate concentrations for each flavonoid will be selected. In the second phase, we will assess the antibacterial activity of the experimental adhesive systems on S. mutans, and their antiproteolytic activity on dentin matrix metalloproteinases. Likewise, the most appropriate adhesive formulations will be used in the last phase to assess the mechanical stability, marginal sealing quality, and proteolytic activity of the resin-dentin bond adhesive interfaces produced in CAD. The number of replicates (n) will vary according to data obtained on each experimental occasion and adjusted for each experimental protocol. Data distribution (Shapiro-Wilk) and homoscedasticity (Levene) will be evaluated to guide the selection of the statistical methods. The statistical inferences will be made considering a level of significance of 5%. (AU)