title: Antimicrobial activity and stability of electron beam irradiated dental irrigants.
abstract: BACKGROUND
  The electron beam (e-beam) radiation is considered as an effective means of sterilization of healthcare products as well as to induce the structural changes in the pharmaceutical agents/drug molecules. In addition to structural changes of pharmaceutical it also induces the formation of low molecular weight compounds with altered microbiological, physicochemical and toxicological properties. Among the several known medicaments, sodium hypochlorite (NaOCl) and chlorhexidine digluconate (CHX) are used as irrigants in dentistry to kill the pathogenic microorganisms like Enterococcus faecalis, Staphylococcus aureus, Streptococcus mutans and Candida albicans inhabiting the oral cavity.
  
  
  OBJECTIVE
  The aim of this study was to evaluate the antimicrobial activity and stability of e-beam irradiated dental irrigants, NaOCl and CHX.
  
  
  METHODS
  Two dental irrigants NaOCl (1.25% and 2.5%) and CHX (1% and 2%) were exposed to various doses of e-beam radiation. The antimicrobial activities of e-beam irradiated irrigants were compared with the non-irradiated (control) irrigants against E. faecalis, S. aureus, S. mutans and C. albicans by disc diffusion method. Following the storage, physico-chemical properties of the irrigants were recorded and the cytotoxic effect was evaluated on human gingival fibroblast cells.
  
  
  RESULTS
  The irrigants, 1.25% NaOCl and 1% CHX showed significantly increased antimicrobial activity against both E. faecalis, (16+0.0) and S. aureus (25+0.0) after irradiation with 1 kGy e-beam. Whereas, 2.5% NaOCl and 2% CHX showed slightly increased antimicrobial activity only against S. aureus (28+0.0). The significant difference was noticed in the antimicrobial activity and cytotoxicity of irradiated and non-irradiated irrigants following the storage for 180 d at 4(0)C.
  
  
  CONCLUSIONS
  The e-beam irradiation increased the antimicrobial activity of irrigants without altering the biocompatibility.
authors.affiliation: Associate Professor, Department of Microbiology, K.S.Hegde Medical Academy, Nitte University , Deralakatte, Karnataka, India .
authors.forename: A Veena
authors.initials: AV
authors.lastname: Shetty
authors.affiliation: Senior Research Fellow, BRNS Project, Nitte University , Deralakatte, Karnataka, India .
authors.forename: A
authors.initials: A
authors.lastname: Geethashri
authors.affiliation: Senior Research Fellow, BRNS Project, Nitte University , Deralakatte, Karnataka, India .
authors.forename: K J
authors.initials: KJ
authors.lastname: Palaksha
authors.affiliation: Senior Research Fellow, BRNS Project, Nitte University , Deralakatte, Karnataka, India .
authors.forename: K R
authors.initials: KR
authors.lastname: Sridhar
authors.affiliation: Senior Research Fellow, BRNS Project, Nitte University , Deralakatte, Karnataka, India .
authors.forename: Ganesh
authors.initials: G
authors.lastname: Sanjeev
keywords: Antimicrobial activity; Cytotoxicity; Dental irrigants; Electron beam irradiation