Interactions between Irrigants Commonly Used in Endodontic Practice: A Chemical Analysis

The orange-brown precipitate observed in the association between CHX and NaOCl occurs because of the presence of NaOCl, an oxidizing agent causing chlorination of the guanidino nitrogens of the CHX. The precipitates formed in the reaction of CHX with EDTA, saline solution, and ethanol were associated with acid-base reactions, salting-out process, and lower solubility, respectively. NaOCl associated with EDTA, citric acid, and phosphoric acid leads mainly to chlorine gas formation. Intermediate flushes with distilled water seem to be appropriate to prevent or at least reduce formation of by-products.