Chemical interaction of alexidine and sodium hypochlorite

Hyeon Sik Kim, Qiang Zhu, Seung Ho Baek, Il Young Jung, Won Jun Son, Seok Woo Chang, Woocheol Lee, Yu Gu, Yoon Lee, Sung Tae Hong, Kwang Shik Bae, Ji Woong Kim, Kun Cho, Kee Yeon Kum

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21 Citations (Scopus)


Introduction: Recent studies have reported the color change and formation of precipitates containing para-chloroaniline (PCA) after a reaction of sodium hypochlorite (NaOCl) and chlorhexidine (CHX). Alexidine (ALX), a biguanide disinfectant similar to CHX, has greater affinity for bacterial virulence factors than CHX. This study determined by electrospray ionization mass spectrometry (ESI-MS) and scanning electron microscopy (SEM) whether the chemical interaction between ALX and NaOCl results in PCA or precipitates. Methods: ESI-MS was performed on 4 different concentrations of ALX (1%, 0.5%, 0.25%, and 0.125%) with 4% NaOCl to detect the presence of PCA. As control groups, 1% ALX, 0.5% PCA, and a mixture of 2% CHX and 4% NaOCl were analyzed. The formation of precipitates on the dentinal surfaces of premolar root canals treated with the solutions of ALX and NaOCl (AN) or CHX and NaOCl (CN) was observed by SEM and the color change in the reaction solutions was also analyzed. Results: ESI-MS showed that the peak (mass/charge ratio = 128.026) in the PCA spectrum was not detected in any of the 4 AN solutions, whereas the peak was found in the CN solution. SEM revealed precipitates covering dentinal surfaces in the CN solution. The AN solutions produced no precipitate. The AN solutions changed in color from light yellow to transparent with decreasing ALX concentration, whereas peach-brown discoloration was observed in the CN solution. Conclusions: The interaction of ALX and NaOCl did not produce PCA or precipitates, and the color of the reacted solution changed transparent with decreasing ALX concentration.

Original languageEnglish
Pages (from-to)112-116
Number of pages5
JournalJournal of endodontics
Issue number1
Publication statusPublished - 2012 Jan

Bibliographical note

Funding Information:
Supported by grants from the National Research Foundation (NRF) of Korea funded by the Ministry of Education, Science and Technology (MEST) (no. 2009-0086835 ), Republic of Korea.

All Science Journal Classification (ASJC) codes

  • Dentistry(all)


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