title: Interaction between Octenidine-based Solution and Sodium Hypochlorite: A Mass Spectroscopy, Proton Nuclear Magnetic Resonance, and Scanning Electron Microscopy-based Observational Study.
abstract: BACKGROUND
  Octenisept (OCT; Schülke & Mayr, Nordersdedt, Germany), an antimicrobial, antibiofilm agent and a promising root canal irrigant, can be potentially combined with sodium hypochlorite (NaOCl) during endodontic treatment. The aim of this study was first to identify the precipitate formed on the interaction between OCT and NaOCl and secondly to compare its effect on dentinal tubules with that of precipitate formed on combining chlorhexidine (CHX) and NaOCl.
  
  
  METHODS
  This observational study was conducted in 3 stages. Initially, the color changes and precipitate formation were assessed when the test solution 0.1% OCT and 5.2% NaOCl were mixed. Color changes were compared with those observed when 2% CHX was mixed with 5.2% NaOCl. The residue obtained on combining OCT and NaOCl was subjected to proton nuclear magnetic resonance (1H NMR) and mass spectrometric (MS) analysis. In the final stage, dentinal surfaces irrigated alternatively with OCT and NaOCl were compared using scanning electron microscopy (SEM) with the dentinal surface irrigated with CHX and NaOCl.
  
  
  RESULTS
  The OCT-NaOCl mixture changed in color from initial milky white to transparent over time, whereas the CHX-NaOCl mixture showed an immediate peach-brown discoloration.1H NMR and MS analysis established that the whitish precipitate obtained on combining OCT and NaOCl solutions correlated with the structure of phenoxyethanol (PE). SEM revealed dense precipitate occluding the dentinal tubules with the CHX and NaOCl group, whereas the precipitate was sparse and partially occluded in the OCT and NaOCl group.
  
  
  CONCLUSIONS
  The whitish precipitate formed with the OCT-NaOCl mixture was identified as PE, a compound already present in OCT, and it partly occluded the dentinal tubules.
authors.affiliation: Department of Conservative Dentistry and Endodontics, Government Dental College, Trivandrum, Kerala, India.
authors.forename: Khaleel Ahamed
authors.initials: KA
authors.lastname: Thaha
authors.affiliation: Department of Organic Chemistry, National Institute for Interdisciplinary Science and Technology, Trivandrum, Kerala, India.
authors.forename: R Luxmi
authors.initials: RL
authors.lastname: Varma
authors.affiliation: Department of Conservative Dentistry and Endodontics, Government Dental College, Trivandrum, Kerala, India.
authors.forename: Mali G
authors.initials: MG
authors.lastname: Nair
authors.affiliation: Department of Conservative Dentistry and Endodontics, Government Dental College, Trivandrum, Kerala, India.
authors.forename: V G
authors.initials: VG
authors.lastname: Sam Joseph
authors.affiliation: School of Dentistry, University of Queensland, Brisbane, Australia. Electronic address: drunni@yahoo.com.
authors.forename: Unni
authors.initials: U
authors.lastname: Krishnan
mesh_terms: D011232:Chemical Precipitation; D005026:Ethylene Glycols / Q000737:chemistry; D007097:Imines; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008855:Microscopy, Electron, Scanning; D011725:Pyridines / Q000737:chemistry*; D012388:Root Canal Irrigants / Q000737:chemistry*; D012973:Sodium Hypochlorite / Q000737:chemistry*; D012996:Solutions
chemical_list: D005026:Ethylene Glycols; D007097:Imines; D011725:Pyridines; D012388:Root Canal Irrigants; D012996:Solutions; D012973:Sodium Hypochlorite; C005398:phenoxyethanol; C034213:octenidine
keywords: Chlorhexidine; Octenidine; irrigants; nuclear magnetic resonance; precipitate; sodium hypochlorite