MMP9 and periodontal disorder: Several studies have shown that salivary concentrations of MMP‐8 and MMP‐9, the two MMPs regulated by TIMP‐1, have a high diagnostic value for periodontal disease.24, 25, 26 This has resulted in the suggestion that TIMP‐1, like MMP‐8 and MMP‐9, could serve as a diagnostic biomarker for periodontal disease.