In the gelatin zymography assay, MMP-9 levels were higher in both periodontitis and gingivitis groups compared to control specimens, but with no statistical significance; MMP-2 activity was higher in gingivitis and aggressive periodontitis samples and lower in chronic periodontitis samples, both compared to the control group, with a statistically significant lower value for the chronic periodontitis group compared to the gingivitis group. This evidence concerns the gene MMP9 and chronic periodontitis.