Conclusion Fluoride may inhibit tooth-germ cell proliferation by restraining the expression of Cyclin D1 and PCNA leading to the abnormal tooth development .

结论F~-可能通过抑制cyClinD1和PCNA的表达 引起细胞增殖的抑制，导致牙 胚发育异常。

Result The human tooth germs continued developing and tooth-germ cells ( ameloblast and odontoblast ) differentiated into more progressive stage in vitro .

结果人乳牙牙胚在体外培养 期间继续发育， 牙齿 形成细胞（成釉细胞和成牙本质细胞）分化 程度进 &步提高。