Zymographic Analysis and Characterization of MMP-2 and -9 Forms in Human Sound Dentin

TLDR

The role of dentin matrix metalloproteinases in caries and resin‑bond degradation remains poorly understood. The study tests the null hypothesis that MMP‑9 is absent from dentin matrix. The authors extracted and isolated all gelatinolytic MMPs from demineralized mature sound dentin powder using gelatin zymography, then identified the enzymes by Western blotting. Gelatinolytic MMP‑2 and MMP‑9 were detected in demineralized dentin extracts, with acidic extracts yielding 3–8 times more activity than EDTA, indicating that their activation may contribute to dentin matrix degradation during caries progression and resin bonding, and that inhibiting these enzymes could slow caries and enhance bond durability.

Abstract

The role and function of dentin matrix metalloproteinases (MMPs) are not well-understood, but they may play a key role in dentinal caries and the degradation of resin-bonded dentin matrices. To test the null hypothesis that MMP-9 is not found in dentin matrix, we used gelatin zymography to extract and isolate all molecular forms of gelatinolytic MMPs in demineralized mature sound dentin powder obtained from extracted human molars, characterizing and identifying the enzymes by Western blotting. Gelatinolytic MMPs were detected in extracts of demineralized dentin matrix and identified as MMP-2 and MMP-9. Acidic extracts (pH 2.3) yielded 3–8 times more MMP activity than did EDTA (pH 7.4). Their activation may contribute to dentin matrix degradation, which occurs during caries progression and following resin bonding. Inhibition of MMP-2 and -9 proteolytic activity may slow caries progression and increase the durability of resin-dentin bonds.