title: The Effect of Addition of an EPS Degrading Enzyme with and without Detergent to 2% Chlorhexidine on Disruption of Enterococcus faecalis Biofilm: A Confocal Laser Scanning Microscopic Study.
abstract: BACKGROUND
  Enterococcus faecalis is one of the most commonly occurring organisms retrieved from root canal treated teeth that show refractory apical periodontitis. Though it is well known that the ability of E. faecalis to form a matrix-encased biofilm contributes to its pathogenicity, the role of extracellular dextran and DNA in biofilm formation and its effect on the susceptibility of the biofilm to chlorhexidine remains poorly understood. It was hypothesized that the addition of an Extracellular Polymeric Substance (EPS) degrading enzyme along with a detergent to chlorhexidine may increase the susceptibility of the E. faecalis biofilm.
  
  
  OBJECTIVE
  To evaluate the sensitivity of Enterococcus faecalis biofilms treated with DNase enzyme and their susceptibility to 2% chlorhexidine used alone or in conjunction with a detergent in a dentin disinfection model and examine under confocal laser scanning microscopy (CLSM).
  
  
  METHODS
  Semi cylindrical shaped dentin specimens were infected with E. faecalis and incubated for 24 hours. Following incubation, the infected dentin specimens were exposed for 3 minutes to the four disinfecting solutions and grouped accordingly. {Group I- Sterile saline, Group II- 2% Chlorhexidine (CHX), Group III- Dnase1 Enzyme + 2% CHX, Group IV- DNase1 Enzyme + 2% CHX & Tween 80. Bacterial viability was then assessed by staining the specimens and examining under CLSM to analyse the proportion of dead and live bacteria within the dentinal tubules.
  
  
  RESULTS
  The Groups II, III and IV showed statistically significant (p<0.05) percentage of dead bacteria compared to the control (Group I). However there was no significant difference in the killing effectiveness within the experimental groups (II-IV) at (p<0.05).
  
  
  CONCLUSIONS
  EPS degrading enzyme (DNase I) disrupts the biofilm and increases the susceptibility of E.faecalis when exposed to 2% Chlorhexidine and the use of a surfactant with this combination significantly contributes to improving the antibacterial efficacy.
authors.affiliation: Professor, Department of Conservative Dentistry & Endodontics, Faculty of Dental Sciences, Sri Ramachandra University , Porur, Chennai, India .
authors.forename: Arathi
authors.initials: A
authors.lastname: Ganesh
authors.affiliation: Senior Lecturer, Department of Restorative Dentistry, International Medical University , Kula Lumpur, Malaysia .
authors.forename: Venkateshbabu
authors.initials: V
authors.lastname: Nagendrababu
authors.affiliation: Former Post Graduate, Department of Conservative Dentistry & Endodontics, Faculty of Dental Sciences, Sri Ramachandra University , Porur, Chennai, India .
authors.forename: Aby
authors.initials: A
authors.lastname: John
authors.affiliation: Dean, Professor and Head, Department of Conservative Dentistry & Endodontics, Faculty of Dental Sciences, Sri Ramachandra University , Porur, Chennai, India .
authors.forename: Kandaswamy
authors.initials: K
authors.lastname: Deivanayagam
keywords: Bacterial viability; Confocal laser scanning microscope; DNase1; Dentinal tubules; Tween 80