Morphological appearance and growth curve of DPSCs at different passages. (A) DPSCs at the 1st passage. (B) DPSCs at the 9th passage. Many DPSCs became enlarged and elongated with one or two cellular processes. (C) Growth curve of DPSCs at the 1st and 9th passages. Population doubling time (PDT) in DPSC-P1 and DPSC-P9 group was 1.83 d and 3.42 d respectively. Values are mean ± s.d., n = 3. Scale bars: 50 μm.