Original: Periodontal Tissue Reaction to Mechanical Stress in Mice

In this paper, we examined the periodontal tissue reaction course of mice to mechanical stress according to the Waldo method, before examination of the transcription factor profile change. In the examination group, the arrangement of the periodontal ligament was irregular on specimen day 1. The extension and compression sites were observed at the opposite side of the roots. In day 1 and 3 specimens, the osteoclasts appeared in the compression sites. In day 7 specimens, the number of osteoclasts was reduced in number to less than that of day 3. Immunohistochemical examination revealed that the expression patterns of Runx2 and Msx2 were clearly dynamic changed compared to the control specimens. These results suggest that the appearance of transcription factors related to cell differentiation of periodontal ligament, which was due to the mechanical stress of insertion of elastic separator, happened within 24 hours.