BACKGROUND: It is difficult to culture human dental pulp cells in vitro. Studies regarding effects of growth factors on proliferation and differentiation of dental pulp cells cultured in vitro have been reported. However, little is known about the Chinese herb rhizoma drynariae decoction on dental pulp cells cultured in vitro.OBJECTIVE: To observe the effects of different concentrations of rhizoma drynariae decoction on the proliferation and differentiation of human dental pulp cells cultured in vitro.DESIGN, TIME AND SETTING: A controlled observation was performed at the Scientific Resaarch Center, Fourth Hospital, Hebei Medical University between March 2006 and May 2007.MATERIALS: Human dental pulp cells were sourced from the patients who acquired orthotherapy through pulling out impacted wisdom tooth at the Department of Stomatology, Fourth Hospital, Hebei Medical University. Written informed content of sample collection was obtained from all patients. Rhizoma drynariae (place of production: Yunnan Province in China) was provided by the Dispensary of Traditional Chinese Medicine, Fourth Hospital, Hebei Medical University.METHODS: Human dental pulp cells were cultured in vitro using method of tissue piece. The effective ingredients of rhizoma drynariae were extracted by alcohol deposition. 1 mL of physic liquor contained 1 g crude drug and diluted into 10, 50, 100, 500, and 1000 mg/L culture medium utilizing fetal bovine serum. Subsequently, the prepared culture medium was used to culture human dental pulp cells in vitro. Cells that were cultured using culture medium without rhizoma drynariae decoction were used as controls.MAIN OUTCOME MEASURES: ①Primary culture and source identification of human dental pulp cells. ②Effects of different concentrations of rhizoma drynariae decoction on proliferation of human dental pulp cells by methyl thiazolyl tetrazolium (MTT) assay. ③ Effects of different concentrations of rhizoma drynariae decoction on fibronectin expression in human dental pulp cells by immunohistochemistry. ④ Effects of rhizoma drynariae decoction on ultrastructure of human dental pulp cells utilizing scanning electron microscope and transmission electron microscope.RESULTS: Primarily cultured human dental pulp cells displayed polygon- and shuttle-shaped appearance. Different concentrations of rhizoma drynariae decoctions, in particular 100 mg/L, exhibited proliferation-promoting effects on proliferation of human dental pulp cells, and could induce dental pulp cell synthesis and secrete fibronectin. Electron microscopy results revealed that following treatment of rhizoma drynariae decoctions, human dental pulp cells were found with abundant ridges on their surface, surround by extracellular matrix, cytoplasm full of abundant rough endoplasmic reticulum and dissociative ribosome, as well as evenly dispersed nuclear euchromatin, and occasionally seen heterochromatin.CONCLUSION: 100 mg/L rhizoma drynadae decoction apparently promotes the proliferation of human dental pulp cells cultured in vitro.