title: Chemical interaction of alexidine and sodium hypochlorite.
abstract: BACKGROUND
  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.
authors.affiliation: Department of Conservative Dentistry, Dental Research Institute, School of Dentistry, Seoul National University, Seoul, South Korea.
authors.forename: Hyeon-Sik
authors.initials: HS
authors.lastname: Kim
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhu
authors.forename: Seung-Ho
authors.initials: SH
authors.lastname: Baek
authors.forename: Il-Young
authors.initials: IY
authors.lastname: Jung
authors.forename: Won-Jun
authors.initials: WJ
authors.lastname: Son
authors.forename: Seok-Woo
authors.initials: SW
authors.lastname: Chang
authors.forename: Woocheol
authors.initials: W
authors.lastname: Lee
authors.forename: Yu
authors.initials: Y
authors.lastname: Gu
authors.forename: Yoon
authors.initials: Y
authors.lastname: Lee
authors.forename: Sung-Tae
authors.initials: ST
authors.lastname: Hong
authors.forename: Kwang-Shik
authors.initials: KS
authors.lastname: Bae
authors.forename: Ji-Woong
authors.initials: JW
authors.lastname: Kim
authors.forename: Kun
authors.initials: K
authors.lastname: Cho
authors.forename: Kee-Yeon
authors.initials: KY
authors.lastname: Kum
mesh_terms: D000814:Aniline Compounds / Q000032:analysis / Q000737:chemistry; D001641:Bicuspid / Q000648:ultrastructure; D001645:Biguanides / Q000737:chemistry*; D011232:Chemical Precipitation; D002710:Chlorhexidine / Q000737:chemistry; D003116:Color; D019551:Dental Disinfectants / Q000737:chemistry*; D003786:Dental Pulp Cavity / Q000648:ultrastructure; D003804:Dentin / Q000648:ultrastructure; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D012388:Root Canal Irrigants / Q000737:chemistry*; D012973:Sodium Hypochlorite / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D000814:Aniline Compounds; D001645:Biguanides; D019551:Dental Disinfectants; D012388:Root Canal Irrigants; D012973:Sodium Hypochlorite; C001570:alexidine; D002710:Chlorhexidine; C004658:4-chloroaniline