Effect of sodium hypochlorite and EDTA on mercury released from amalgam

Objectives. The effect of sodium hypochlorite (NaOCl) and EDTA on mercury r eleased from dental amalgam was assessed in vitro. Study design. Fifty-six samples of dental amalgam of similar size were prep ared and exposed to a 10-mL solution of either 1% NaOCl, 3% NaOCl, 10% EDTA in 1% NaOCl, or 10% EDTA in 3% NaOCl for periods of 20, 40, and 60 minutes , Mercury concentrations in the solutions were measured by using a cold-vap or atomic absorption Mercury Analyzer System, and the differences between t he groups were statistically analyzed. Results. All amalgam samples exposed to 1% NaOCl and 3% NaOCl-either alone or in combination with EDTA-released mercury into the solutions. Mercury re lease was significantly higher in the test groups than in the EDTA, distill ed water, or phosphate buffer controls (P < .001). Increase in the mean con centration levels of mercury in solution was time-dependent and directly re lated to NaOCl concentration. The addition of EDTA caused a reduction in me rcury levels detected in solution, which was more significant in amalgam sa mples exposed to 1% NaOCl combined with EDTA (P < .001). Conclusions. NaOCl solutions commonly used for root canal cleaning and shap ing cause mercury release from dental amalgam and may alter its chemo-physi cal properties as a sealant for root perforations.