Biology,College of Life Sciences,Central China Normal University,Wuhan 430079,China Objective To assess the effect of ZrO2 Nano-particles(NPs) on the viability of human oral cells in vitro.Methods Human epidermoid carcinoma(KB) cells were exposed to ZrO2 NPs with different concentrations(0、10、30、 60、100、150、250 μg.ml-1) for 24,48,72 h.MTT assay was used to analyze the viability of KB Cells.Results ① The viability of KB cells was increased by low concentration ZrO2 NPs at 24 and 48 hours’ exposure time.② At the same time,high con...