MMP9 and periodontitis: Also, in the same study, there were stronger correlations in patients in periodontal health than in those with chronic periodontitis between the total MMP9 and MMP9/NGAL complex, with authors attributing it to the fact that most of MMP forms found in GCF of periodontal healthy patients come from PMNs, while in patients with periodontal disease they might be from other sources also [12].