Insight into the Reaction of Alexidine with Sodium Hypochlorite: A Potential Error in Endodontic Treatment

Therapeutic success in endodontic treatment depends on successful infection control. Alexidine dihydrochloride (ALX) was recently proposed as a potential alternative to 2% chlorhexidine (CHX) as it possesses similar antimicrobial properties, expresses substantivity and does not produce p-chloroaniline (PCA) when mixed with sodium hypochlorite (NaOCl). However, the products released in this reaction have not been described to date. The aim of this study was to identify detected chemical compounds formed in the reaction of ALX and NaOCl with the ultra-high-performance liquid chromatography-mass spectrophotometry (UHPLC-MS) method and assess whether precipitates and PCA are formed in this reaction. Solutions of ALX were mixed with the equivalent volume of 2% and 5.25% (w/v) NaOCl solutions. As control, 2% (w/v) CHX was mixed with 2% and 5.25% (w/v) NaOCl. Samples were subjected to the UHPLC-MS analysis. The mixture of ALX and NaOCl resulted in a yellowish precipitate formation, the amount of which depended on NaOCl concentration. Interaction of ALX and NaOCl resulted in the production of aliphatic amines. No PCA was formed when NaOCl was mixed with ALX. However, for the first time, we identified the possible products of the interaction. The interaction between NaOCl and ALX results in the formation of aliphatic amines; therefore, these compounds should not be mixed during endodontic treatment.