Expression of MMP-9 and -13 on the Pressure Side under Orthodontic Loading

Purpose: The purpose of this study was to investigate the expression of MMP-9 and MMP-13 on compression side of tooth movement. Material and Methods: Twenty male Wistar rats were used for this experiment. Maxillary right first molar was moved orthodontically with a constant force of 20 g and on the side of the maxillary left first molar was used as control group. On the 4th, 10th and 17th days after experiment, 5 rats were euthanized, respectively. Histologic process was processed for immunohistochemical staining of MMP-9 and -13. Results: MMP-9 and -13 expressions were upregulated at day 4 after tooth movement. The expression of MMP-9 was not observed at days 7, 10 and 14, while the expression of MMP-13 was greatly increased at days 7 and 10. Conclusion: This study suggests that different characteristics of MMPs expression may contribute to the remodeling process of collagen fibers in the PDL during tooth movement.