In mixed biofilms Enterococcus faecalis benefits from a calcium hydroxide challenge and culturing

S.V. van der Waal, T. Connert, W. Crielaard, J.J. de Soet

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Aim

To evaluate the fate of Enterococcus faecalis in dual‐species and multispecies biofilms after treatment with calcium hydroxide (Ca(OH)2).

Methodology

Biofilms were cultured from laboratory strains of E. faecalis and Pseudomonas aeruginosa, or from microbiota retrieved from primary root canal infections. The biofilms were then treated with Ca(OH)2. The proportion of E. faecalis and P. aeruginosa and their susceptibility to disinfection were evaluated in a viability assay. In the mixed‐species assay, the presence and proportions of E. faecalis before and after Ca(OH)2 treatment were evaluated with a quantitative polymerase chain reaction assay. Groups were compared using Mann–Whitney U‐test and Student's t‐tests. An α <0.05 was considered statistically significant.

Results

After Ca(OH)2 treatment in dual‐species biofilms, the proportion of E. faecalis had increased (< 0.001), whereas the total number of CFUs per biofilm was equal. Enterococcus faecalis was equally susceptible to disinfection by sodium hypochlorite (NaOCl) or by chlorhexidine. Pseudomonas aeruginosa had become more susceptible to NaOCl disinfection. The root canal isolates contained no detectable amounts of E. faecalis. After biofilm culturing or Ca(OH)2 treatment, it appeared that E. faecalis must have been present in 5 of 6 (83%) root canal samples.

Conclusions

Calcium hydroxide favours the population of E. faecalis in a dual‐species biofilm. Culturing multispecies root canal isolates makes E. faecalis detectable. E. faecalis was often present in primary endodontic infections, albeit in low numbers.

Original languageEnglish
Pages (from-to)865-873
JournalInternational Endodontic Journal
Volume49
Issue number9
Early online date3 Sept 2015
DOIs
Publication statusPublished - Sept 2016

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