Interaction between sodium hypochlorite and chlorhexidine gluconate

By Basrani BR, Manek S, Sodhi RN, Fillery E, Manzur A

Date: 05/2008
Journal: JOE


•Purpose: to determine the minimum concentration of NaOCl that causes color change and precipitate formation when mixed with 2.0% CHX, and to characterize the resulting precipitate 

Materials &  Methods:

•a serial dilution technique was used.

• X-ray photon spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) were used to qualify and quantify the precipitate. A

• color change and precipitate were induced in 2.0% CHX by 0.023 % and 0.19 % NaOCl, respectively. 

  •To characterize the precipitate, a new set of six flat-top polypropylene microtubes were prepared with diluted concentrations of NaOCl (6.0%, 3.0%, 1.5%, 0.75%, 0.38%, and 0.19%) and 0.5 mL of 2.0% CHX was added.


•Color change occurred in all nine microtubes where CHX was added, including the one with lowest concentration of 0.023% NaOCl. 

•As the concentration of NaOCl increased, the color range varied from peach to brown

  •color change and the precipitate occurred immediately and showed no change with time. 

•Both XPS and TOF-SIMS showed the presence of para-chloroaniline in an amount directly related to the concentration of NaOCl used. 

Clinical significance:

The formation of the precipitate should be avoided by removing the NaOCl before placing CHX into the canal.