Interactions of ethylenediamine tetraacetic acid with sodium hypochlorite in aqueous solutions

By Grawehr M, Sener B, Waltimo T, Zehnder M

Date: 01/2003
Journal: IEJ


To evaluate interactions of EDTA with NaOCl.


  • solutions consisting of 8.5% EDTA and 0.5% NaOCl were compared to a 1:1 mixture of 17% EDTA and 1% NaOCl for their Ca chelating ability, tissue dissolving ability, and antimicrobial properties
  • amounts of available Cl determined in solutions using iodine/thiosulfate titration
  • Ca chelation capacity titrated with pure Ca solution using murexide indicator
  • weight loss of porcine palatal mucosal specimens incubated in solutions measured over time
  • antimicrobial potential measured using agar diffusion test with E. faecalis


  • presence of NaOCl had little effect on EDTA’s chelating ability or antimicrobial effect
  • available Cl content decreased by 0.06% in EDTA/NaOCl mixes vs. 0.5% in NaOCl/H2O
  • EDTA/NaOCl did not dissolve more tissue vs. pure EDTA

Clinical Significance:

When mixed, EDTA retains chelating ability but NaOCl loses its tissue dissolving ability. Minimize usage together.