This in vitro study monitored MMP-8 production on PMN by stimulated with the following three groups; Sonicated extracts of E. faecalis (SEF), SEF treated with Ca(OH)₂ (12.5mg/ml) for 7 days, and lipopolysaccharides (LPS) of E. coli. The level of MMP-8 in each group was immediately measured by ELISA. The data were analyzed with Kruskal-Wallis test and Mann-Whitney U test.

In the SEF group, the level of production of MMP-8 was higher than the negative control group in low concentration (0.05µg/ml) of SEF (p < 0.05), but it decreased with an increase in the concentration of SEF (p < 0.05). In the case of SEF treated with Ca(OH)₂, all of the MMP levels were higher than negative control group (p < 0.05), but no statistical difference was found among the different SEF concentrations (p > 0.05). All of the levels in E. coli LPS were increased with increasing concentrations (p < 0.05).

According to this study we could summarize as follows:

1. MMP-8 was expressed at low level in untreated PMN group and the levels of MMP-8 were upregulated in PMN stimulated by E. coli LPS groups.

2. In the SEF groups, the level of production of MMP-8 decreased with an increase in the concentration of SEF (p < 0.05). So E. faecalis may have suppressive effect on the production of MMP-8 by PMN.

3. In the case of SEF treated with Ca(OH)₂, all of the MMP levels at different SEF concentrations were higher than untreated PMN group (p < 0.05), but no statistical difference was found among the different SEF concentrations (p > 0.05).