title: Residual antibiofilm effects of various concentrations of double antibiotic paste used during regenerative endodontics after different application times.
abstract: OBJECTIVE
  We investigated the residual antibiofilm effects of different concentrations of double antibiotic paste (DAP) applied on radicular dentin for 1 or 4 weeks.
  
  
  METHODS
  Dentin samples were prepared (n=120), sterilized and pretreated for 1 or 4 weeks with the clinically used concentration of DAP (500mg/mL), low concentrations of DAP (1, 5 or 50mg/mL) loaded into a methylcellulose system, calcium hydroxide (Ca(OH)2), or placebo paste. After the assigned treatment time, treatment pastes were rinsed off and the samples were kept independently in phosphate buffered saline for 3 weeks. Pretreated dentin samples were then inoculated with Enterococcus faecalis and bacterial biofilms were allowed to grow for an additional 3 weeks. Biofilms were then retrieved from dentin using biofilm disruption assays, diluted, spiral plated, and quantified. Fisher's Exact and Wilcoxon rank sum tests were used for statistical comparisons (α=0.05).
  
  
  RESULTS
  Dentin pretreatment for 4 weeks with 5, 50 or 500mg/mL of DAP demonstrated significantly higher residual antibiofilm effects and complete eradication of E. faecalis biofilms in comparison to a 1 week pretreatment with similar concentrations. However, dentin pretreated with 1mg/mL of DAP or Ca(OH)2did not provide a substantial residual antibiofilm effect regardless of the application time.
  
  
  CONCLUSIONS
  Dentin pretreatment with 5mg/mL of DAP or higher for 4 weeks induced significantly higher residual antibiofilm effects in comparison to a 1 week pretreatment with the same concentrations.
authors.affiliation: Department of Endodontics, Indiana University School of Dentistry, Indianapolis, IN, USA.
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Jenks
authors.affiliation: Department of Endodontics, Indiana University School of Dentistry, Indianapolis, IN, USA.
authors.forename: Ygal
authors.initials: Y
authors.lastname: Ehrlich
authors.affiliation: Department of Endodontics, Indiana University School of Dentistry, Indianapolis, IN, USA.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Spolnik
authors.affiliation: Department of Biomedical and Applied Sciences, Indiana University School of Dentistry, Indianapolis, IN, USA.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Gregory
authors.affiliation: Department of Biomedical and Applied Sciences, Indiana University School of Dentistry, Indianapolis, IN, USA. Electronic address: gyassen@iupui.edu.
authors.forename: Ghaeth H
authors.initials: GH
authors.lastname: Yassen
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D058491:Bacterial Load / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects*; D003804:Dentin / Q000187:drug effects / Q000382:microbiology; D004708:Endodontics / Q000379:methods*; D013293:Enterococcus faecalis / Q000187:drug effects; D006801:Humans; D008826:Microbial Sensitivity Tests; D009824:Ointments / Q000008:administration & dosage; D011897:Random Allocation; D012038:Regeneration / Q000187:drug effects*; D012388:Root Canal Irrigants / Q000494:pharmacology; D014092:Tooth Root / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents; D009824:Ointments; D012388:Root Canal Irrigants
keywords: Antibacterial effect; Bacterial biofilm; Calcium hydroxide; Double antibiotic paste; Enterococcus faecalis