title: Cysteamine Enhances Biofilm Eradication Efficacy of Calcium Hydroxide.
abstract: BACKGROUND
  Calcium hydroxide (Ca[OH]2) is a widely used interappointment dressing, but its antibacterial property is compromised by dentin. Hence, the addition of chlorhexidine (CHX) with Ca(OH)2 has been proposed. However, the antimicrobial efficacy of this mixture compared with Ca(OH)2 alone is currently still debatable. Cysteamine is a mucolytic agent used to reduce the viscosity of mucus through the disruption of proteins, which are also important components of the extracellular matrix of biofilms. The aims of this study were to determine the efficacy of cysteamine alone and in combination with Ca(OH)2 to eradicate Enterococcus faecalis biofilm compared with CHX with Ca(OH)2, and to determine if this effect is affected by dentin.
  
  
  METHODS
  The biofilm eradication efficacies of Ca(OH)2 alone and with cysteamine were determined using 7-day E. faecalis biofilm cultured on dentin discs and compared with Ca(OH)2 with 2% CHX. The effects of dentin on the efficacies of Ca(OH)2 alone and with either cysteamine or CHX were examined.
  
  
  RESULTS
  Cysteamine alone completely abolished E. faecalis biofilm at 200 mg/mL. The combination of Ca(OH)2 with either cysteamine at 10 mg/mL or 2% CHX completely obliterated E. faecalis biofilm. Cysteamine with Ca(OH)2 completely eradicated E. faecalis biofilm despite preincubation with dentin, whereas CHX with Ca(OH)2 was less effective.
  
  
  CONCLUSIONS
  Cysteamine effectively eliminated E. faecalis biofilm and showed synergistic effects in combination with Ca(OH)2, which were unaffected by dentin. Hence, our findings support the use of cysteamine as a potential adjunct to Ca(OH)2 as an interappointment dressing.
authors.affiliation: Faculty of Dentistry, National University of Singapore, Singapore.
authors.forename: Weidi
authors.initials: W
authors.lastname: Guo
authors.affiliation: Faculty of Dentistry, National University of Singapore, Singapore.
authors.forename: Samantha Yiling
authors.initials: SY
authors.lastname: Quah
authors.affiliation: Faculty of Dentistry, National University of Singapore, Singapore.
authors.forename: Kian Chong
authors.initials: KC
authors.lastname: Lim
authors.affiliation: Faculty of Dentistry, National University of Singapore, Singapore.
authors.forename: Victoria Soo Hoon
authors.initials: VS
authors.lastname: Yu
authors.affiliation: Faculty of Dentistry, National University of Singapore, Singapore. Electronic address: denkst@nus.edu.sg.
authors.forename: Kai Soo
authors.initials: KS
authors.lastname: Tan
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D058491:Bacterial Load / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects*; D002126:Calcium Hydroxide / Q000494:pharmacology*; D002710:Chlorhexidine / Q000494:pharmacology; D003543:Cysteamine / Q000008:administration & dosage / Q000494:pharmacology*; D003804:Dentin / Q000187:drug effects; D004338:Drug Combinations; D004357:Drug Synergism; D013293:Enterococcus faecalis / Q000187:drug effects; D005100:Expectorants; D008422:Materials Testing; D050296:Microbial Viability / Q000187:drug effects; D018613:Microscopy, Confocal; D012388:Root Canal Irrigants / Q000008:administration & dosage / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D004338:Drug Combinations; D005100:Expectorants; D012388:Root Canal Irrigants; D003543:Cysteamine; D002126:Calcium Hydroxide; D002710:Chlorhexidine
keywords: Calcium hydroxide; Enterococcus faecalis; endodontic biofilm; intracanal dressing; mucolytics