No difference in TIMP−1 levels between the groups at baseline, or after therapy. MMP−8/ TIMP−1 ratio was significantly higher in the periodontitis group compared to the healthy controls at baseline (p = .03). Periodontal treatment of the periodontitis patients resulted in a significantly lower MMP−8/TIMP−1 ratio (p = .001). This evidence concerns the gene TIMP1 and periodontitis.