Matrix metalloproteinases in human sclerotic dentine of attrited molars.

OBJECTIVE

The relationship between the major proteinases in dentine matrix metalloproteinases (MMPs) and the formation of collagen-less sclerotic dentine is still unknown. This study is to compare the concentrations of dentinal MMP-1, -2, -3, -8, and -9 between human sound and sclerotic dentine.

DESIGN

Eleven sound third molars from young patients and twenty-two attrited molars with sclerotic dentine from old patients were collected and three groups of dentine samples were obtained: sound dentine of young tooth (SDY), non-sclerotic dentine of attrited tooth (NDA) and sclerotic dentine of attrited tooth (SDA). The dentine powder from each group was subjected to demineralization and protein extraction in turn. Then the contents of MMP-1, -2, -3, -8 and -9 were quantitatively evaluated by Fluorescent Microsphere Immunoassay. The occlusal and fractured axial surfaces of sound and sclerotic dentine were observed using FEI-SEM.

RESULTS

There was no significant difference in the concentration of MMP-1 amongst all tested groups (p>0.05). The contents of MMP -2 and MMP-3 in SDY were significantly higher than those in NDA and SDA (p<0.05). The contents of MMP -8 and MMP -9 in SDA were significantly higher than those in SDY and NDA (p<0.05). The surface hypermineralised layer and sclerotic casts were all detected in sclerotic dentine under SEM.

CONCLUSIONS

The morphological characteristics of sclerotic dentine from the attrited molars were comparable to that from noncarious cervical lesions. Although depended on the type of MMP, the contents of dentinal MMPs changed during the formation of sclerotic dentine and long-term ageing.