EC Dental Science

Objective: This in vitro study evaluated the effect of ethylenediaminetetraacetic acid as an intermediate irrigant to prevent the for- mation of para-chloroaniline related precipitate when reacting sodium hypochlorite and chlorhexidine.

Material and Methods: Different concentrations of sodium hypochlorite and ethylenediaminetetraacetic acid were mixed. 2% Chlorhexidine was added and the precipitate formation was visualized. Formed para-chloroaniline was quantified by spectropho- tometry.

Results: Combinations of 0.05%, 0.5% and 5% sodium hypochlorite, 2% Chlorhexidine and most ethylenediaminetetraacetic acid di- lutions formed precipitates of assorted colors. Mixtures of 0.05% sodium hypochlorite with 0.0010%, 0.0017%, 0.010% and 0.017% ethylenediaminetetraacetic acid plus 2% Chlorhexidine did not form any kind of precipitate. Extrapolation indicates that an ethyl- enediaminetetraacetic acid concentration of 0.03278% would prevent the formation of para-chloroaniline at a sodium hypochlorite concentration of 0.05%.

Conclusion: Ethylenediaminetetraacetic acid as an intermediate irrigant between sodium hypochlorite and chlorhexidine partially inhibits the formation of para-chloroaniline in a direct concentration ratio: the higher the concentration, the greater the formation inhibition of para-chloroaniline related precipitate.

Keywords: Chlorhexidine; Ethylenediaminetetraacetic Acid; Para-Chloroaniline; Sodium Hypochlorite; Spectrophotometry

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