Relationship between the salivary concentration of matrix metalloproteinases 8 and 20 and severe early childhood caries

Dental caries is initiated through mineral dissolution by bacterial acids and collagen degradation by endogenous proteolytic enzymes, mainly collagenolytic matrix metalloproteinases (MMPs).The present research aimed to evaluate the relationship between severe early childhood caries (S-ECC) and salivary MMP-8 and MMP-20 concentrations.Fifty children aged 36-60 months were assigned to either the caries-free (control) group or the S-ECC group. Standard clinical examinations were performed, and approx. 1 mL of expectorated unstimulated whole saliva was collected from all participants. In the S-ECC group, the sampling was repeated 3 months after restorative treatment. All samples were analyzed for the salivary concentrations of MMP-8 and MMP-20, using the enzyme-linked immunosorbent assay (ELISA). Statistical analysis employed the t test, the Mann-Whitney U test, the χ2 test, Fisher's exact test, and the paired samples t test. The level of significance was set at 0.05.At baseline, the subjects in the S-ECC group presented with significantly elevated levels of MMP-8 as compared to the control group. However, the salivary concentration of MMP-20 did not exhibit a significant difference between the 2 groups. A significant reduction occurred in the levels of MMP-8 and MMP-20 3 months after restorative treatment in the S-ECC group.The salivary levels of MMP-8 and MMP-20 were significantly affected by dental restorative treatment in children. Furthermore, MMP-8 was observed to be a better indicator of the dental caries status than MMP-20.