Abstract:

Objective　To observe the effect of matrix metalloproteinase-1(MMP-1) from human host on degradation of dentin organic matrix of root dentin.Methods　The freshly extracted caries-free impacted teethwere selected. Teethwere cuttransverse- ly under the enamel-cementum junction into dentin sections with a thickness of about 5 mm. Then all sections with removal of ce- mentum, pulp and predentin were randomly divided into four groups. In the first group, dentin sections were demineralized with acid solution for 21 days, and then incubated withMMP-1 solution for 7 days; the second group were only treated with acid solu- tion for 21 days; the third group were only attacked byMMP-1 solution for 7 days; and the fourth group were untreated as a con- trol. Then all sectionswere dehydrated in ascending strength of alcohol, critically dried, coated with platinum, and then observed under scanning electron microscope(SEM).Results　The dentin sections of root surface attacked by acid andMMP-1 showed that demineralization of dentin mineral and degradation of dentin matrix fibrae synchronously happened. The dentin matrix fibrae wasn′t degradated in the groups treatedwith acid orMMP-1.Conclusion　The proteinases from human hostmay play an important role in the development of root surface caries. MMP-1 may distinctly degradate the organic matrix of demineralized dentin.

Key words: matrix metalloproteinase-1, dentin, root surface caries, scanning electron microscope