Objective

  This study evaluated the inhibitory effect of proanthocyanidin (PA), a natural collagen cross-linker, on soluble and matrix-bound proteases, which are responsible for progressive degradation of exposed collagen fibrils within the hybrid layer and resin–dentine bond failure over time.

 Methods

  The inhibitory effects of PA (1%, 2%, 3%, 4.5% and 6%) on soluble recombinant matrix metalloproteinases (MMP-2, -8 and -9) and cysteine cathepsins (cathepsin B and K) were evaluated using MMP and cysteine cathepsins fluorometric assay kits. Chlorhexidine (CHX) was used as an inhibitor control. The effect of PA on endogenous matrix-bound proteases was examined by determining the change in dry mass of demineralized dentine beams and solubilized collagen peptides over 30 days. Two-way ANOVA and Tukey multiple comparison tests were used to analyze the effect of PA and proteases on the percentage inhibition of soluble proteases (α=0.05). Kruskal–Wallis one-way ANOVA and Dunn's multiple comparison tests were used to analyse the effect of PA on loss of dry mass and hydroxyproline content over time (α=0.05).

 Results

  Proanthocyanidin inactivated more than 90% of soluble recombinant MMP-2, -8 and -9 and around 75–90% of cysteine cathepsin B and K, which was significantly higher than CHX (P<0.05). The inhibition of endogenous proteases by PA increased in a dose-dependent manner. The loss of dry mass and hydroxyproline release in the medium over time was the lowest in dentine beams pretreated with PA < CHX <(P<0.05).

 Conclusion

 Proanthocyanidin exibited both dentine MMP cysteine cathepsins inhibition, which was higher than chlorhexidine.

 Source: Journal of Dentistry

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