Abstract: Objective： To investigate the correlation between matrix metalloproteinase (MMP)-2/MMP-9 levels and childhood caries, and the saliva levels of MMP-2/MMP-9 among healthy children and those with different degrees of dental caries, both before and after treatment. Methods: In the study, 368 children aged 3 to 5 years were separated into three groups: severe caries group (112 children), mild caries group (98 children) and caries free group (158 children). The children with severe caries were included in treatment group (83 children) after accepting a comprehensive treatment of caries. MMP-2 and MMP-9 levels were determined by enzyme-linked immunosorbent assay (ELISA) and the data were analyzed by the Statistics Package for Social Science (SPSS 13.0). The differences among severe caries group, mild caries group and caries free group were analyzed by SNK-q (Student Newman Keuls). The severe caries group and treatment group were compared by paired t test. The differences between each group were statistically analyzed. Results: There was no significant difference of the age and gender composition among severe caries group, mild caries group, caries free group and treatment group. The MMP-2 level of severe caries group ［(141.3±32.5) μg/L］ was higher than those of mild caries group ［(107.5±21.3) μg/L］ and caries free group ［(102.8±18.5) μg/L］ (P<0.05). There was no significant difference between mild caries and caries free group (P>0.05). After analysis of 83 children in the treatment group, the level of MMP2 ［(120.1±24.8) μg/L］ was lower than before ［(144.6±30.3) μg/L］ (P<0.05), but was higher than that of caries free group (P<0.05). The MMP-9 levels of severe caries group ［(445.8±68.1) μg/L］ and mild caries group ［(428.6±59.2) μg/L］ were higher than that of caries free group ［(385.4±60.6) μg/L］ (P<0.05), but the difference between severe caries group and mild caries group was not significant (P>0.05). After analysis of 83 children in the treatment group, the alteration of MMP-9 ［(432.2±64.7) μg/L］ was not significant either (P>0.05). Conclusion: The saliva levels of MMP-2 and MMP-9 in children with severe caries were higher than those in caries free children, even if the treatment was implemented, which suggests that the MMP-2 and MMP-9 in saliva might be related to the caries in children.

Key words: Dental caries, Matrix metalloproteinase 2, Matrix metalloproteinase 9, Saliva, Child