Abstract
Introduction
Endodontic infections are caused by polymicrobial biofilms. Therefore, novel root
canal disinfectants should be evaluated not only on single-species biofilms but also
on dual- or mixed-species biofilms. A simple, high-throughput assay is urgently needed
for this. In this study, the application of the resazurin metabolism assay was investigated
for the evaluation of a root canal disinfectant on dual-species biofilms.
Methods
Enterococcus faecalis with or without Streptococcus mutans in biofilms were formed in an active attachment biofilm model for 24 hours. Subsequently,
the biofilms were treated with various concentrations of NaOCl for 1 minute. After
resazurin metabolism by both organisms was confirmed, treatment efficacies using 0.0016%
resazurin were evaluated.
Results
During NaOCl treatments, resazurin metabolism displays a clear dose response, not
only in single-species E. faecalis (or S. mutans) biofilms but also in dual-species biofilms. Notably, the assay revealed that the
resistance of dual-species biofilms to NaOCl was 30-fold higher than in single-species
E. faecalis biofilms. Viability counts on a selected NaOCl treatment (0.004%) confirmed this
result and showed the increased resistance of E. faecalis in dual-species biofilms.
Conclusions
Clearly, the high-throughput and low cost resazurin metabolism assay has a great potential
for testing novel root canal antimicrobial agents in mixed-species biofilms.
Key Words
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Article info
Publication history
Published online: November 15, 2010
Footnotes
Supported by the Dutch Technology Foundation STW, which is the applied science division of NWO, and the Technology Program of the Ministry of Economic Affairs.
Identification
Copyright
© 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.
