Figure 3. (AQ) Increased level of matrix metalloproteinase (MMP)-3 during orthodontic tooth movement. (A) A partial fixed orthodontic appliance was put in place to push the impacted third molar for various time periods before extraction. The bone covering the impacted tooth was then removed and collected for further analysis. Immunolocalization of MMP-3 in samples of the no-force control group (B) and of experimental groups with 3 (C) and 7 days (D) of compression. Soft tissue around the alveolar bone—including periodontal ligament, marrow, and blood vessels—was immunoreactive. The bony edge showed significant staining (arrows). Representative Figs. are shown, and specific staining at the bony edge was with 2x magnification for a more detailed view. Scale in (B) = 100 µm; same magnification for (C) and (D).