MPO and periodontitis: The significant decrease in the levels of aMMP-8, the rate of aMMP-8 RFU activity, tMMP-8, and MPO, as well as in the levels of bleeding on probing, the visible plaque index, the mean of PPD, the mean of CAL, and the number of at least 4 mm periodontal pockets, showed a positive and beneficial treatment effect in these patients with periodontitis.