Figure 5.

Real-time PCR. (A) Type I collagen (Col1A1), (B) alkaline phosphatase (Alp), and (C) osteocalcin (Oc) in MC3T3-E1 cells on titanium (Ti) or zirconia (Zr) discs after 2, 6, 10, and 15 d of culture in osteogenic medium. The data are expressed as the mean ± SD of 3 independent experiments. *Significant differences between groups (P < 0.05). (D) ALP staining. Cells were seeded onto the discs and cultured in osteogenic medium for 7 d. ALP activity was determined by cytochemical staining as indicated in “Materials and Methods,” (E) Alizarin red S staining. Cells were seeded onto the discs and cultured in osteogenic medium for 21 d. Staining procedure is described in “Materials and Methods.”