Meta-analysis of the association between serum and gingival crevicular fluid matrix metalloproteinase-9 and periodontitis

The authors of this meta-analysis evaluated whether there is a difference in the levels of serum and gingival crevicular fluid (GCF) matrix metalloproteinase (MMP)-9 between patients with periodontitis and periodontally healthy control participants.The authors searched PubMed, Embase, the Cochrane Library, and the China Biology Medicine disk databases for eligible studies in which the investigators reported the relationships between MMP-9 levels in serum and GCF and periodontitis. The authors pooled the standardized mean differences (SMDs) and 95% confidence intervals (CIs) from each study to evaluate the difference in the serum and GCF MMP-9 levels between patients with periodontitis and periodontally healthy control participants.Results of a meta-analysis of 6 case-control studies including a total of 923 healthy control participants and 557 patients with periodontitis indicated that serum MMP-9 levels were significantly higher in patients with periodontitis than in periodontally healthy control participants (SMD, 1.60; 95% CI, 0.17 to 3.03; P.05). Results of a separate meta-analysis of 6 case-control studies including a total of 153 healthy control participants and 189 patients with periodontitis indicated that GCF MMP-9 levels were significantly higher in patients with periodontitis than in periodontally healthy control participants (SMD, 1.96; 95% CI, 0.76 to 3.16; P.01).The results of the meta-analysis revealed statistically significant differences in the MMP-9 levels in serum and GCF between patients with periodontitis and periodontally healthy control participants. These results cannot be used to confirm causality because the included studies were all case-control studies in which the investigators reported associations. Moreover, readers should view the results with caution because of the considerable heterogeneity among the studies included in the meta-analysis.