Figure 3: Indirect Cytotoxic Evaluation of EP, ST (Shuetz), ZK (Zirkonzhan) Y-TZP extracts and the Medium (control group). The data is expressed as the mean values at 24, 48 and 72 hours. A difference was shown between the cell viability at 72 hrs (letter a) compared to 48 hrs (letter b) for the EP and ST.