title: Combined Antibacterial Effect of Sodium Hypochlorite and Root Canal Sealers against Enterococcus faecalis Biofilms in Dentin Canals.
abstract: BACKGROUND
  The present study aimed to evaluate the antibacterial effect of the combined use of sodium hypochlorite (NaOCl) and root canal sealers on Enterococcus faecalis biofilms using a dentin infection model.
  
  
  METHODS
  Cells of E. faecalis were introduced into the dentinal tubules by centrifugation and incubated in brain-heart infusion for 3 weeks. The biofilms in dentin were first subjected to 5% NaOCl or sterile water for 10 minutes followed by an equal thickness of AH Plus (Dentsply International Inc, York, PA), Endosequence BC Sealer (Brasseler USA, Savannah, GA), or MTA Fillapex (Angelus Indústria de Produtos Odontológicos S/A, Londrina, Brazil) placed on the root canal wall of the dentin specimens for 7, 30, and 60 days. Gutta-percha and water were used in a similar manner as controls. The proportions of dead and live bacteria inside the dentinal tubules were assessed by confocal laser scanning microscopy and viability staining.
  
  
  RESULTS
  The combined use of NaOCl and sealers (30 and 60 days) killed significantly more bacteria than NaOCl or sealers alone (P < .05). NaOCl + MTA Fillapex was the most effective antibacterial combination by killing 83% bacteria in dentin tubules in 60 days. Thirty and 60 days of exposure to the sealers resulted in significantly more dead bacteria in dentin biofilms than 7-day exposures (P < .05).
  
  
  CONCLUSIONS
  The placement of root canal sealer after NaOCl treatment enhanced antibacterial effects against E. faecalis in the dentinal tubules. Little additional effect was obtained after 30 days of exposure to sealers.
authors.affiliation: Department of Stomatology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, China; Faculty of Dentistry, Division of Endodontics, Department of Oral Biological and Medical Sciences, University of British Columbia, Canada.
authors.forename: Tianfeng
authors.initials: T
authors.lastname: Du
authors.affiliation: Faculty of Dentistry, Division of Endodontics, Department of Oral Biological and Medical Sciences, University of British Columbia, Canada; The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China.
authors.forename: Zhejun
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Faculty of Dentistry, Division of Endodontics, Department of Oral Biological and Medical Sciences, University of British Columbia, Canada; Department of Materials Engineering, University of British Columbia, Vancouver, Canada.
authors.forename: Ya
authors.initials: Y
authors.lastname: Shen
authors.affiliation: Department of Stomatology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Jingzhi
authors.initials: J
authors.lastname: Ma
authors.affiliation: Department of Stomatology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Yingguang
authors.initials: Y
authors.lastname: Cao
authors.affiliation: Faculty of Dentistry, Division of Endodontics, Department of Oral Biological and Medical Sciences, University of British Columbia, Canada. Electronic address: markush@dentistry.ubc.ca.
authors.forename: Markus
authors.initials: M
authors.lastname: Haapasalo
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D003804:Dentin / Q000187:drug effects / Q000382:microbiology* / Q000473:pathology; D004359:Drug Therapy, Combination; D013293:Enterococcus faecalis / Q000187:drug effects*; D004853:Epoxy Resins / Q000494:pharmacology; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy* / Q000473:pathology; D006801:Humans; D018613:Microscopy, Confocal; D012387:Root Canal Filling Materials / Q000494:pharmacology*; D012973:Sodium Hypochlorite / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D004853:Epoxy Resins; D012387:Root Canal Filling Materials; C534916:epoxy resin-based root canal sealer; D012973:Sodium Hypochlorite
keywords: Confocal laser scanning microscopy; Enterococcus faecalis; dentin; sealer; sodium hypochlorite