Objective Observing the function and meaning of bone morphogenetic protein（BMP）-2 expression in different stages of tooth germ development. Methods Applied immunohistochemical techniques to examine the expression of BMP-2 in different stages of the tooth germs of human fetus in 8-36 weeks, the rat born after 1-22 d, and the dog postnatal in 6 weeks to 5 months. Results BMP-2 expressed in all stages of every tooth germ. In human fetus, the positive reaction observed in epithelium of tooth bud, dental plate, enamel organ, external and outer enamel epithelium, dental papilla and dental follicle at bud stage and cap stage. While at bell stage cells in external enamel, stratum intermedium cell, ameloblasts and odontoblasts showed strong positive expression. The ameloblasts, odontoblasts, Hertwig epithelial root sheath and dental follicle showed strong positive reaction in the unerupted human deciduous tooth, the tooth under the eruption of neonate rat and 6 week′s postnatal canal tooth. Positive expressions of BMP-2 were observed in root of tooth, peridental ligament and the osteoblasts adjoin to peridental ligament in the dog succession of deciduous teeth. Conclusion BMP-2 is one of critical regulators in tooth development, which regulate the differentiation and morphogenesis of tooth germ cells and control the eruption of teeth and succession of deciduous teeth at different stages.
