Inhibition of human gelatinases by metals released from dental amalgam

The interaction between metal ions and the oral environment is a major subj ect matter in dental research. Matrix metalloproteinases (MMPs) have been i mplicated in pathologic oral processes such as periodontal tissue destructi on, root caries, tumor invasion and temporomandibular joint disorders. The aim of this study was to test the effect of metal ions released From dental amalgam on the major gingival gelatinolytic MMPs. Gingival human explants were cultured overnight in DMEM and the activity of secreted enzymes was an alyzed by gelatin zymography in buffers conditioned with dispersed phase or concentional phase dental amalgams. The major enzymes present in condition ed media were characterized as MMP-2 and MMP-9 by immunoprecipitation. The proteolytic activities of MMP-2 and MMP-9 were strongly inhibited by disper sed phase amalgams conditioned buffers. Inhibition of MMP-2 and MMP-9 activ ities was partly prevented by the addition of 1.10 phenanthroline, a divale nt metal chelator, to the amalgam conditioned buffers. Dental amalgam condi tioned buffer also inhibited the degradation of denatured type I collagen b y purified MMP-2 on liquid phase assays. These findings suggest that the ac tivity of oral tissue MMPs may be modulated by metal ions released from den tal amalgam. (C) 2001 Elsevier Science Ltd. All rights reserved.