title: Decreased bacterial adherence and biofilm growth on surfaces coated with a solution of benzalkonium chloride.
abstract: BACKGROUND
  Secondary biofilm formation by oral bacteria after breakdown/fracture of temporary or permanent restorations imposes a challenge to the outcome of root canal treatment. This study focuses on benzalkonium chloride (BAK) coating on dentin or polystyrene surfaces and its influence on the early adhesion and biofilm formation by oral and root canal bacteria.
  
  
  METHODS
  Microbial adhesion and biofilm growth on surfaces coated with BAK were analyzed qualitatively with a dentin disk model and quantitatively with a mini-flow cell biofilm model. Cell viability and total biovolume were analyzed by the LIVE/DEAD technique. The repelling effect of surfaces coated with BAK was compared with NaOCl. Uncoated surfaces were used as controls.
  
  
  RESULTS
  Scanning electron microscope images in the dentin disk model revealed that very sparse biofilms were formed on NaOCl- and BAK-coated dentin surfaces. In contrast, biofilms formed on uncoated dentin were clearly visible as numerous irregularly distributed aggregates of rods and cocci. In the mini-flow cell system, confocal laser scanning microscope analysis confirmed that biofilms formed on NaOCl- and BAK-coated surfaces showed significantly less adhesion (2 hours) and biovolume accumulation (24 and 96 hours) compared with the uncoated controls (P < .01). Furthermore, cell viability assessments showed that on uncoated controls the viability measurements were high (>89%) as well as on BAK-coated surfaces (88% viable cells). However, cell viability was significantly reduced on NaOCl-coated surfaces (59% viable cells).
  
  
  CONCLUSIONS
  This study illustrates that surface coating with a surfactant solution containing BAK does not cause cell membrane damage but might interfere with cell mechanisms of adhesion. Investigations into the clinical utility of BAK as an antibiofilm medication are warranted.
authors.affiliation: Department of Endodontics, School of Dentistry, Loma Linda University, Loma Linda, California 92350, USA. djaramillo@llu.edu
authors.forename: David E
authors.initials: DE
authors.lastname: Jaramillo
authors.forename: Alberto
authors.initials: A
authors.lastname: Arriola
authors.forename: Kamran
authors.initials: K
authors.lastname: Safavi
authors.forename: Luis E
authors.initials: LE
authors.lastname: Chávez de Paz
mesh_terms: D000328:Adult; D000891:Anti-Infective Agents, Local / Q000494:pharmacology*; D001422:Bacterial Adhesion / Q000187:drug effects*; D001548:Benzalkonium Compounds / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D015169:Colony Count, Microbial; D003786:Dental Pulp Cavity / Q000382:microbiology*; D003804:Dentin / Q000382:microbiology*; D015194:Diffusion Chambers, Culture; D013293:Enterococcus faecalis / Q000187:drug effects; D006801:Humans; D007778:Lactobacillus / Q000187:drug effects; D050296:Microbial Viability / Q000187:drug effects; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D012463:Saliva / Q000382:microbiology; D012973:Sodium Hypochlorite / Q000494:pharmacology; D054773:Streptococcus gordonii / Q000187:drug effects; D013501:Surface-Active Agents / Q000494:pharmacology
chemical_list: D000891:Anti-Infective Agents, Local; D001548:Benzalkonium Compounds; D013501:Surface-Active Agents; D012973:Sodium Hypochlorite