The presence of smear layer affects the antimicrobial action of root canal sealers

R F Zancan, A Di Maio, P L Tomson, M A H Duarte, J Camilleri

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AIM: To assess the chemical and microstructural characteristics of dentine after the use of two irrigation protocols and correlate this with the antimicrobial properties of hydraulic calcium silicate cement (HCSC) sealers and changes to the dentine structure/chemistry after sealer placement.

METHODOLOGY: Two irrigation protocols - Protocol A using 2% NaOCl used 5 mL/5 min and Protocol B with 2% NaOCl (5 mL/5 min) followed by 17% EDTA (5 mL/3 min) - were used to prepare dentine. The chemical and microstructural changes following irrigation were assessed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Fourier transform infrared (FT-IR) spectroscopy (n = 5) on dentine obtained from the mid-root and coronal parts of extracted human teeth. Four sealers (AH Plus, BioRoot, MTA Fillapex, TotalFill) were characterized by SEM/EDS (n = 3). The ability of the sealers to eradicate intratubular Enterococcus faecalis biofilms was assessed by live/dead dye and confocal laser scanning microscopy to measure the percentage of living cells. The effect of combined irrigation and root filling on dentine was assessed by SEM and EDS analysis (n = 5). Statistical analysis was undertaken using one-way anova and a number of post hoc tests to detect intergroup differences. The F-test was used for comparison of variances in the microbiology testing.

RESULTS: The use of NaOCl alone left the smear layer intact, with traces of chlorine remaining on dentine. The use of BioRoot sealer restored the calcium levels of dentine which had been depleted by the irrigation with EDTA. BioRoot exhibited antimicrobial properties against intratubular bacteria even in the presence of smear layer (Protocol A). Smear layer removal improved the bactericidal effect of all sealers and Ca2+ leaching. The use of a chelating agent was important for the intratubular sealer penetration for AH Plus but not the other sealers.

CONCLUSION: The removal of smear layer was necessary for penetration of AH Plus into the dentinal tubules. BioRoot was a more effective sealer in reducing the bacterial load in the dentinal tubules than the other materials tested and the presence of smear layer did not affect its activity.

Original languageEnglish
Pages (from-to)1369-1382
JournalInternational Endodontic Journal
Issue number8
Early online date24 Mar 2021
Publication statusE-pub ahead of print - 24 Mar 2021

Bibliographical note

Funding Information:
The authors thank Dr. Sarah Kuehne for reviewing the antimicrobial testing protocol and Chuta Kooanantkul for his constant and valuable support. This study was supported by the State of São Paulo Research Foundation, FAPESP (2018/03554‐0).

Publisher Copyright:
© 2021 International Endodontic Journal. Published by John Wiley & Sons Ltd


  • AH Plus
  • BioRoot
  • MTA Fillapex
  • TotalFill BC Sealer
  • antimicrobial activity
  • smear layer

ASJC Scopus subject areas

  • Dentistry(all)


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