Objective To investigate the effects of the different concentration of mineral trioxide aggregate (MTA) on the proliferation and differentiation of dental pulp stem cells (DPSCs) from the young permanent teeth.Methods DPSCs were isolated from the young permanent teeth and cultured by tissue explant method.The expression of STRO-1 was detected by using immunofluorescence technology.DPSCs were cultured with different concentrations of MTA (0.02,0.20,2.00,20.00 g/L).Cell proliferation was detected by MTT array.Cells were cultured in the appropriate concentration of MTA for 4 weeks,and then stained by Alizarin red to detect their mineralized nodule formation capacity.The cells were cultured with the appropriate concentration of MTA and collected after 12,24,36,48 h.The mRNA expression of ALP,BSP,OC and DSP after the treatment of MTA were detected by quantitative PCR.Results DPSCs were positive for STRO-1.The capacity of 0.20 g/L MTA promoting the proliferation of DPSCs was stronger than other concentrations.After 4 weeks,the mineralized nodules of DPSCs were observed after alizarin red staining.The PCR showed that with increasing induction time,the expression levels of DSP and OC were up-regulated.But that of ALP and BSP was increased first and then decreased.Conclusions In this study,MTA can promote the proliferation of DPSCs at 0.02,0.20,2.00 g/L concentration.It can induce odontoblast differentiation effectively by 0.20 g/L MTA.

Objective:To observe the dynamic process of the development of dentin and enamel during their mineralization period. Methods: Dental germs in maxillae and mandibulae were obtained from spontaneously aborted 21 weeks and 32 weeks fetus. The samples were prepared and stained with modified Mallory's trichrome staining and observed under light microscope. Results: Different mineralized layers in different period of development appeared different color variation in the dental germs. Conciusion: Modified Mallory's trichrome staining method may be used to study the mineralization of dental germ.