Figure 5

Real-time PCR measurement of Ameloblastin and Amelogenin gene expression. (A) Real-time PCR Ameloblastin expression at different time points in the bioengineered organ culture. Ameloblastin expression peaked at 60 h. Ameloblastin expression was significantly higher at 72, 84 and 150 h in the FGF-9 group compared with the control group. (B) Real-time PCR Amelogenin expression at different time points of the bioengineered organ culture. Amelogenin expression was significantly higher in the FGF-9 group compared with the control group at 1 h and peaked at 72 h, coinciding with a significant change in ECIS assay (Figure 4B) and due to epithelial invagination. These two graphs show that the peak Ameloblastin expression at 60 h is followed by a peak Amelogenin expression at 72 h, in agreement with previous research [21]. Significantly higher Amelogenin expression also coincides with early lower impedance data (Figure 4B) and earlier differentiation of tooth germ evident in early organ culture (Additional file 2). These results indicate that FGF-9 can initiate early phenotypic and morphological characteristics of ameloblasts within the epithelium, which coincides with epithelial invagination evident from the ECIS assay (Figure 4B). After invagination, the FGF-9 group still exhibits higher Ameloblastin and Amelogenin expressions than the control group. Because of the clear differences, no mark is necessary to specify the results of the FGF-9 group.