Objective: This study tested whether treatment of demineralized dentin with polyacrylic acid (PAA) has any activatory or inhibitory activity on dentin matrix metalloproteinases (MMP)s or cathepsin K (CAT-K).
Methods: Dentin beams (1mm×2mm×6mm; n=10) were completely demineralized with EDTA. After initial dry mass assessment, the beams were dipped into 37% phosphoric acid (PA), PA+2% benzalkonium chloride (BAC), PA+2% chlorhexidine digluconate (CHX), 10% PAA, PAA+BAC or PAA+CHX for 20s. Demineralized beams without treatment served as control. All beams were incubated in simulated body fluid (SBF) for 1 week and the dry mass loss was evaluated. Aliquots of SBF were used to analyze solubilized telopeptide fragments using ICTP as indicator of MMP-mediated collagen degradation and CTX for CAT-K-mediated degradation. Additional demineralized beams (n=10) were used to measure the influence of different chemical treatments on total MMP activity of EDTA-demineralized dentin using generic MMP assay. Data were analyzed by ANOVA (α=0.05).
Results: Dry mass loss ranged from 6% (PA) to 2% for (PA-BAC) or (PAA-BAC) (p<0.05). ICTP release of PAA-treated group was significantly higher (p<0.05) than the control, and not significantly different from the PA group (p>0.05). PA+CHX or PAA+CHX and PAA+BAC showed significantly lower ICTP than PA or PAA groups (p<0.05). CAT-K activity increased significantly after 10% PAA treatment compared to control (p<0.05) or to PA postreatment.
Significance: Demineralized dentin treated with 10% polyacrylic acid activated CAT-K more than 37% phosphoric acid; 2% chlorhexidine digluconate seems to be a better inhibitor of MMPs and CAT-K than 2% benzalkonium chloride.
Keywords: Cysteine cathepsins; Degradation; Dentin; Matrix metalloproteinase; Polyacrylic acid.
Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.