MMP8 and periodontitis: It was observed that the concentration of MMP-8 in each group of patients varied significantly, that is, from 0.21 to 20.70 ng/mL in patients with healthy periodontium, from 0.20 to 31.50 ng/mL in patients with mild periodontitis, from 0.34 to 54.90 ng/mL in patients with moderate periodontitis, and finally from 0.20 to 48.51 ng/mL in patients with severe periodontitis.