Survival of Enterococcus faecalis in root canals ex vivo

C. M. Sedgley, S. L. Lennan, O. K. Appelbe

Research output: Contribution to journalArticlepeer-review

121 Scopus citations


Aim: The hypotheses tested in this study were that: (i) Enterococcus faecalis can survive long-term entombment in root filled teeth without additional nutrients, (ii) initial cell density influences the survival of E. faecalis in instrumented root canals and (iii) gelatinase-production capacity influences the survival of E. faecalis in root canals. Methodology: The root canals of 150 extracted single canal teeth were instrumented to apical size 60 and divided into six groups of 25. Within each group 10 canals were inoculated with either gelatinase-producing E. faecalis OG1-S and the other 10 with its gelatinase-defective mutant E. faecalis OG1-X. Five canals per group were kept as uninoculated controls. The root canals in groups 1 and 2 were inoculated with 106 bacteria, incubated for 48 h at 37°C then filled with gutta-percha and zinc-oxide eugenol sealer. Root canals were inoculated with 106, 105, 104 and 103 bacteria in groups 3-6, respectively, and left unfilled. All teeth were sealed coronally with glass-ionomer cement. After 6- (groups 1, 3-6) and 12-month (group 2) incubation at 37°C in 100% humidity, root fragments were analysed for presence of E. faecalis, using culture, polymerase chain reaction and histological methods. Results: Viable E. faecalis was recovered from all root filled teeth and from 95-100% of unfilled inoculated teeth. Initial cell density and gelatinase production did not influence the recovery of viable E. faecalis (P > 0.05; chi-square test). Enterococcus faecalis 16S rRNA gene products were present in all inoculated teeth and absent in all noninoculated controls. Dentinal tubule infection was evident under light microscopy in sections from inoculated teeth after 48-h, 6- and 12-month incubation. Conclusions: Enterococcus faecalis inoculated into root canals maintained viability for 12-months ex vivo. The clinical implications are that viable E. faecalis entombed at the time of root filling could provide a long-term nidus for subsequent infection.

Original languageEnglish (US)
Pages (from-to)735-742
Number of pages8
JournalInternational Endodontic Journal
Issue number10
StatePublished - Oct 2005
Externally publishedYes


  • Enterococcus faecalis
  • In vitro
  • Root canal
  • Root filling
  • Survival

ASJC Scopus subject areas

  • Dentistry(all)


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