Methods: Dentin powder was pulverized from freshly extracted human molars. Five lots of dentin powder were obtained and processed as follow: 1) untreated mineralized dentin; 2) demineralized with 1% H3PO4 for 10 min; demineralized with 1% H3PO4 for 10 min then treated with 3) ATA (30% in volume), 4) with MCMS (30% in volume) or 5) METMAC (30% in volume). Extracts obtained from the treated dentin powder were then electrophoresed by gelatin zymography, for detection of MMPs enzyme activity.
Results: No enzymatic activity was found in proteins extracted from mineralized dentin. Zymograms of demineralized dentin extracts showed MMP-2 and -9 active forms (66 and 86-kDa isoforms, respectively). Zymograms of 30% ATA-treated dentin showed reduction of MMP-2 proform (72-KDa) and active form and complete inhibition of MMP-9, while zymograms of 30% MCMS and METMAC-treated dentin showed complete inhibition of MMP-2 pro-form and MMP-9 active form and a reduction in MMP-2 active form.
Conclusions: This study supports the hypothesis that QAMs can inhibit dentin MMPs. Further studies are needed to clarify how much the addition of QAMs into dentin bonding agents can be beneficial for the durability of the bond.