The inhibitory effects of quaternary ammonium methacrylates on soluble and matrix-bound MMPs

Matrix metalloproteinases (mmps) bound to dentin contribute to the progressive degradation of collagen fibrils in hybrid layers created by dentin adhesives. this study evaluated the mmp-inhibiting potential of quaternary ammonium methacrylates (qams),with soluble rhmmp-9 and a matrix-bound endogenous mmp model. six different qams were initially screened by a rhmmp-9 colorimetric assay. for the matrix-bound endogenous mmps,we aged demineralized dentin beams for 30 days in calcium- and zinc-containing media (cm; control),chlorhexidine,or qams in cm to determine the changes in dry mass loss and solubilization of collagen peptides against baseline levels. the inhibitory effects of qams on soluble rhmmp-9 varied between 34 and 100%. beams incubated in cm showed a 29% decrease in dry mass (p < 0.05),whereas beams incubated with qams showed only 0.2%-6% loss of dry mass. significantly more solubilized collagen was detected from beams incubated in cm (p < 0.05). it is concluded that qams exhibited dentin mmp inhibition comparable with that of chlorhexidine,but required higher concentrations. © 2011 international & american associations for dental research.