AIM: To study whether epidermal growth factor ( EGF) participates in the formation of soft andhard tissue passage during tooth eruption. METHODS: Immunohistochemical method was used to examine the expressions of EGF/EGFR in oral mucosa located in the corona of the erupting mandibular first molars of BACB/C mice. Dental follicle was harvested from 4-6 day postnatal Wistar vats and cultured in a-MEM with 15% FBS. Cells in third passage were incubated with EGF at different concentrations to choose the best dosage. MTT assays were used to evaluate cell proliferation. Dental follicle cells were challenged with 10ng/mL EGF for 0, 0. 5, 1,3 and 6 hours respectively , and the cells were then collected for RT-PCR assay. The results were analyzed by SPSS13.0 software pack-age. RESULTS: During tooth eruption, weak expression of EGF was found in oral epithelia and strong expression of EGFR was found in enamel epithelium. In adult mice, EGF immunostaining was limited to lamina propria, EGFR im-munostaining was limited to stratum basale. EGF at 5 - 10 ng/mL increased the proliferation of dental follicle cells (P < 0.05), and peak effects were observed at lOng/mL according to MTT assay ( P < 0.05). Exposure of dental fol-licle cells to 10ng/mL EGF for 3h resulted in significant up-regulation of MCP-1 expression(P<0.05). CONCLUSION : Different expressions of EGF/EGFR in oral mucosa at different stage of tooth eruption indicate that EGF might facilitate the formation of the epithelial mass. And it may play an important role in the formation of the soft tissue passage during tooth eruption. Proper concentrations of EGF can promote dental follicle cell proliferation and up-regulate MCP-1 expression in the dental follicle cells. Therefore, EGF might facilitate alveolar bone resorption.%目的:研究表皮生长因子(EGF)在牙齿萌出过程中,是否参与软、硬组织通道的形成.方法:①免疫组化法检测表皮生长因子及其受体在出生后13、15 d以及成年小鼠下颌第一磨牙萌出部位口腔黏膜的表达变化；②原代培养Wistar大鼠牙囊细胞,选择生长良好的第3代细胞,MTT法筛选EGF作用于牙囊细胞的较佳效应浓度.将第3代牙囊细胞以1×105/孔接种到培养皿中,加入最佳浓度的EGF孵育0.5、1、3、6h后,Trizol一步法分别提取总RNA,采用反转录聚合酶链反应(RT-PCR)检测同一浓度的EGF作用不同时间后,牙囊细胞MCP-1 mRNA的表达变化.结果:①牙萌出时,EGF在萌出牙齿冠方黏膜的上皮层呈弱阳性表达,表皮生长因子受体(EGFR)在口腔上皮全层呈强阳性表达.而牙萌出后,EGF的表达集中于口腔黏膜的固有层,EGFR的表达集中于上皮基底层；②在EGF浓度为5～10 ng/mL时,对牙囊细胞的增殖具有明显促进作用(P＜0.05),其中10 ng/mL促进作用最强.牙囊细胞与10 ng/mL的EGF共同孵育0.5、1、3、6h均能明显促进牙囊细胞MCP-1 mRNA的表达(P＜0.05),其中3h时促进作用最强,以后逐渐恢复,但仍比对照组高(P＜0.05).结论:EGF及其受体可能促进萌出牙齿冠方实性上皮团的形成；适当浓度的EGF能显著增加牙囊细胞的增殖活性,并上调牙囊细胞中MCP-1 mRNA的表达.
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