Figure 1. The concentrations of MMP-8 (mean + SD) in the GCF of orthodontic (n = 11) and control patients (n = 6) detected with the IFMA analysis. The orthodontic samples (on the left) were collected from the orthodontically moved teeth immediately before fixed appliance activation (0 hr), and at 1-8 hrs after force application. Control GCF samples were collected from the non-orthodontic control patients. The mean GCF MMP-8 concentrations for orthodontically treated teeth at 4-8 hrs were significantly higher than before activation, and when compared with control teeth (Mann-Whitney U-test; p < 0.05).