Figure 1. Zirconium ion promotes HOB proliferation.

(A) The MTT assay was used to determine the HOB viability after HOBs were treated with zirconium solutions with different concentrations for 1, 3 and 7 days. Compared to the control and NaNO3-treated control, higher concentrations of zirconium significantly increased HOB viability. ZrO(NO₃)₂ at 5µM increased cell proliferation at D1 and D3 but not D7, whereas ZrCl₄ at 5µM had no effects on HOB proliferation. However, higher concentrations of both of zirconium solutions significantly increased cell proliferation at D1, D3 and D7. Between the time points, viable cell number in each treatment group are significantly increased (p<0.01). (B) The graph shows the quantification of Ki67 positive cells to total cells. Compared to the control, the proportion of Ki67-positive cells is significantly increased in all treatment groups. There were no significant differences observed between the treatment groups at the different concentrations. (C-J) Representative images from each treatment group following KI67 immunostaining. Arrows indicate the positive staining of cells with the Ki67 antibody (C). Scale bar: 100 µm. Data are Mean±SD of three separate experiments. * p<0.05, **p<0.01 versus control.