Mixing chlorhexidine and sodium hypochlorite forms a precipitate called parachloroaniline (PCA). It is orange-brown in color and, in theory, could compromise the treatment. The compound has also been shown to be toxic and classified as a carcinogen.
Can you irrigate with both of these solutions in one tooth? Sure, just don’t mix them directly. You can irrigate with EDTA or alcohol after the sodium hypochlorite and prior to the chlorhexidine.
The point is to avoid chlorhexidine and hypochlorite from coming in direct contact.
More info here.
Thank you for Dr. McCormick in Mauston for posing the question. We felt it was worth sharing. If you have a particular topic or question don’t hesitate to ask. Thanks Mick!