Evaluation of Cytotoxic Effects of Purified Mercury in Human Gingival Fibroblasts-In vitro Study

Background: Since the introduction of amalgam for tooth fillings, there have been concerns that mercury toxicity could pose unacceptable health risks. Rasa shastra is an ancient medical discipline that focuses on the utilization of metals and minerals for the treatment of diseases. Nevertheless, these minerals cannot be directly administered to the human body in their natural state due to their potential adverse effects. Hence, for medicinal purposes, these metals and minerals need to undergo purification (Shodhana) to eliminate impurities and modify their physical, chemical, and biological characteristics. Methodology: Human gingival fibroblasts (HGF) were exposed to commercially available mercury (CAHg) and ayurvedically purified mercury (AP-Hg) at concentrations of 6.25 mu M, 12.5 mu M, 25 mu M and 50 mu M. The unexposed HGF cultured in basal media was considered a control. All the samples were cultured for 24 hours and 48 hours, and the cytotoxicity was analyzed by MTT assay. Results: Cell viability between the control and experimental groups varied at 24 hours, however, the results were not statistically significant (p>0.05). At 48 hours, cell viability was higher in the AP-Hg group as compared to the CA-Hg group at the concentration of 6.25 mu M, and the difference was statistically significant (p<0.05). The cell proliferation assay results demonstrated a statistically significant difference in the mean optical density values (p<0.05) between CA-Hg and AP-Hg at 12.50 mu M, 25 mu M, and 50, mu M concentrations observed at 24 hours. At 48 hours, a statistically significant difference in the mean OD values (p<0.05) between CA-Hg and AP-Hg at all four concentrations was observed. Conclusion: AP-Hg at a concentration of 6.25 mu M demonstrated higher cell viability at 48 hours. Further, the cell proliferation rate was also higher for AP-Hg at all concentrations at 24 and 48 hours. These results indicated a less cytotoxic effect of AP-Hg than CA-Hg in HGF and hence could be employed for dental amalgam preparations.