Zinc reduces collagen degradation in demineralized human dentin explants.
OBJECTIVE
Dentin 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.


METHODS
Mineralized 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.


RESULTS
Collagen 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.


CONCLUSIONS
Zinc 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.
Department of Dental Materials, School of Dentistry, Campus de Cartuja s/n, University of Granada, E-18071 Granada, Spain. toledano@ugr.es
R
R
Osorio
M
M
Yamauti
E
E
Osorio
M E
ME
Ruiz-Requena
D H
DH
Pashley
F R
FR
Tay
M
M
Toledano
D002614:Chelating Agents / Q000494:pharmacology; D002710:Chlorhexidine / Q000031:analogs & derivatives / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology; D003094:Collagen / Q000187:drug effects*; D024042:Collagen Type I / Q000032:analysis; D003804:Dentin / Q000187:drug effects* / Q000201:enzymology; D004318:Doxycycline / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D008422:Materials Testing; D020778:Matrix Metalloproteinase 2 / Q000494:pharmacology; D061965:Matrix Metalloproteinase Inhibitors; D010455:Peptides / Q000032:analysis; D011489:Protein Denaturation / Q000187:drug effects; D013997:Time Factors; D017001:Tooth Demineralization / Q000378:metabolism*; D015032:Zinc / Q000494:pharmacology*; D017967:Zinc Compounds / Q000494:pharmacology
D002614:Chelating Agents; D002712:Chlorides; D024042:Collagen Type I; D004791:Enzyme Inhibitors; D061965:Matrix Metalloproteinase Inhibitors; D010455:Peptides; D017967:Zinc Compounds; C052929:collagen type I trimeric cross-linked peptide; C016837:zinc chloride; D003094:Collagen; C522361:MMP2 protein, human; D020778:Matrix Metalloproteinase 2; D015032:Zinc; C010882:chlorhexidine gluconate; D004318:Doxycycline; D002710:Chlorhexidine