Zinc reduces collagen degradation in demineralized human dentin explants

ObjectivesDentin matrix metalloproteinases are implicated in the pathogenesis of caries and contribute to collagen degradation in resin–dentin interfaces. The objective was to determine if collagen degradation may be modulated by an excess of zinc or zinc chelators.MethodsMineralized and phosphoric acid demineralized human dentin specimens were tested. Chlorhexidine digluconate, doxycycline or ZnCl2 were added to the media. In half of the groups, active exogenous metalloproteinase-2 was incorporated into the solution. C-terminal telopeptide determinations (radioimmunoassay) were performed after 24 h, 1 and 3 weeks.ResultsCollagen degradation was prominent in demineralized dentin. Doxycycline fully blocked dentin proteolysis. Chlorhexidine digluconate reduced the degradation at the 24-h period. Zinc in excess strongly inhibits hydrolysis of collagen and its effect was maintained for 3 weeks.ConclusionsZinc in excess reduces MMP-mediated collagen degradation. The hypothesis that binding of zinc to collagen results in protection of sensitive cleavage sites of metalloproteinases requires further validation.