ABSTRACT
<p><b>OBJECTIVE</b>To detect the expression and distribution of epidermal growth factor (EGF) and epidermal growth factor receptor (EGFR) in periodontal tissues, and analyze the role of EGF in orthodontic tooth movement.</p><p><b>METHODS</b>According to Kings methods, 40 g mesial force was applied to pull the left maxillary first molar in the rat. Using immunohistochemical method (HI-SABC method) to localize and examine the expression of EGF and EGFR in decalcified alveodental connective tissues at 24 hours and 168 hours of tooth movement.</p><p><b>RESULTS</b>EGF and EGFR were stained at some of periodontal ligament of furcation and radical regions in control group. These expressions of EGF and EGFR increased in periodontal tissues (P < 0.01), with the expressions at 168 hours higher than those at 24 hours (P < 0.01). And levels of EGF and EGFR at tension side were higher than those at pressure side at the same time (P < 0.01).</p><p><b>CONCLUSIONS</b>Epidermal growth factor participated in the tissues remodeling during orthodontic tooth movement and especially played a more important role in orthodontic bone formation.</p>