Residual antibiofilm effects of various concentrations of double antibiotic paste used during regenerative endodontics after different application times

Arch Oral Biol. 2016 Oct;70:88-93. doi: 10.1016/j.archoralbio.2016.06.006. Epub 2016 Jun 7.


Objective: We investigated the residual antibiofilm effects of different concentrations of double antibiotic paste (DAP) applied on radicular dentin for 1 or 4 weeks.

Design: 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)2 did 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.

Keywords: Antibacterial effect; Bacterial biofilm; Calcium hydroxide; Double antibiotic paste; Enterococcus faecalis.

MeSH terms

  • Anti-Bacterial Agents / administration & dosage*
  • Bacterial Load / drug effects
  • Biofilms / drug effects*
  • Dentin / drug effects
  • Dentin / microbiology
  • Endodontics / methods*
  • Enterococcus faecalis / drug effects
  • Humans
  • Microbial Sensitivity Tests
  • Ointments / administration & dosage
  • Random Allocation
  • Regeneration / drug effects*
  • Root Canal Irrigants / pharmacology
  • Tooth Root / drug effects*


  • Anti-Bacterial Agents
  • Ointments
  • Root Canal Irrigants