Abstract

Introduction: 5% sodium hypochlorite (NaOCl), saline (0.9% NaCl), and 2% chlorhexidine (CHX) forms a coloured precipitate parachloroaniline (PCA). NaOCl dilution saline decreases the formation of precipitate but form a white precipitate. Objective: The aim is to study the role of saline in the formation of PCA between NaOCl and CHX. Material and Methods: 5% NaOCl diluted with 0.9% NaCl was mixed with 2% CHX to obtain PCA. NaOCl 0.05% and 0.005% were mixed with 0.9% NaCl and dilutions and 2% CHX, and PCA was quantified. 2% CHX was mixed with 0.9% NaCl and dilutions to form white precipitate. Spectrographic analysis of the precipitates were performed between hypochlorite 0.005%, saline with 2% CHX, and 0.9% NaCl with 2% CHX. Results: Concentrated NaOCl solutions in 0.9% NaCl with 2% CHX formed PCA. Diluted hypochlorite forms a white precipitate. The formed PCA is directly related to concentrations of 0.005% and 0.05% NaOCl. 2% CHX formed precipitate only with 0.9% NaCl. The spectra of the precipitates formed by the reaction between 2% CHX with 0.9% NaCl and the reaction between 0.005% NaOCl with 2% CHX and 0.9% NaCl were equal. Their spectrographic analysis indicated chlorhexidine dihydrochloride. Conclusions: In the reaction between chlorhexidine, sodium hypochlorite, and saline solution, two reactions were obtained: formation of PCA (NaOCl and CHX) and transformation of chlorhexidine digluconate into chlorhexidine dihydrochloride, which is responsible for the white precipitate. Until 0.5 % NaOCl, the first reaction predominates, and under this concentration, the second reaction begins. PCA measurements spectrophotometrically confirm this relationship.