Localization of TNF-α and Macrophages in the Periodontal Ligament during Orthodontic Tooth Movement

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Remodelling of the periodontium after application of mechanical forces constitutes the basis of clinical orthodontics, and various immunoregulatory molecules are involved in this process. The present study focused on the localizations of the tumor necrosis factor-α(TNF-α)and macrophages in periodontalligament(PDL)during experimental tooth movement in rats. A total of 15 male 6-weeks-old Wistar rats were subjected to an orthodontic force of 10g to induce a mesially tipping movement of the upper first molars. Experimental tooth movement was accomplished for seven days. We determined the localization of TNF-α and RM-4(an antibody specific for identification of macrophages)in the PDL during orthodontic tooth movement using immunohistochemistry. Immunoreactivity for TNF-α and RM-4 was detected in PDL fibroblasts in the compressive side by the orthodontic force of 10g. On the first day after tooth movement, the immunoreactivity of TNF-α and RM-4 was weak. On the third and fifth days, more TNF-α and RM-4 positive reactions in some nucleuses of fibroblasts were recognized than on the first day. Furthermore, these positive reactions were decreased after seven days. Therefore, RM-4 (+)cells involved in the expression of TNF-α may play an important role in the initial reaction of the PDL and in the induction of the osteoclastic bone resorption during orthodontic tooth movement.