Elsevier

Journal of Endodontics

Volume 43, Issue 12, December 2017, Pages 2093-2096
Journal of Endodontics

Basic Research
Antibiofilm Activity of Sodium Hypochlorite and Alkaline Tetrasodium EDTA Solutions

https://doi.org/10.1016/j.joen.2017.06.038Get rights and content

Highlights

  • The ATP assay correlates well with the microbial counts to determine E. faecalis on root dentin.

  • EDTANa4 with NaOCl and NaOCl + CTR effectively control biofilms of E. faecalis on dentin.

  • Such solutions could constitute an effective alternative for use as a single irrigating solution.

Abstract

Introduction

The aim of this study was to determine the antimicrobial activity of mixed alkaline tetrasodium EDTA (EDTANa4)/sodium hypochlorite (NaOCl) solutions with and without the addition of cetrimide (CTR) against Enterococcus faecalis biofilms.

Methods

The antimicrobial solutions were evaluated on a 3-week biofilm of E. faecalis grown on radicular dentin blocks. The irrigating solutions were 2.5% NaOCl group, 20% EDTANa4 group, 10% EDTANa4 group, 2.5% NaOCl/10% EDTANa4 group, 2.5% NaOCl/5% EDTANa4 group, 2.5% NaOCl/10% EDTANa4/0.2% CTR group, 2.5% NaOCl/5% EDTANa4/0.2% CTR group, and 0.9% saline solution group. Cell viability was determined by adenosine triphosphate assay, and culture techniques were used to determine colony-forming unit (CFU) counts. In groups with positive growth, the Pearson linear correlation coefficient r (−1 ≤ r ≤ 1) between relative light units (RLUs) and log10 (CFUs + 1) was calculated. The results of the bioluminescence adenosine triphosphate assay and CFUs of the groups were analyzed by means of analysis of variance and the Duncan test.

Results

There was Pearson correlation between RLUs and log10 (CFUs + 1). A similar reduction of RLUs in all NaOCl groups was seen, giving statistical differences with respect to the control. In the NaOCl groups there was no bacterial growth. The lowest antimicrobial efficacy was found for the EDTANa4 groups.

Conclusions

Mixed alkaline EDTANa4/NaOCl solutions with and without the addition of CTR do not interfere with the antimicrobial activity of NaOCl.

Section snippets

Bacteria Strain and Irrigating Solutions

The bacteria used in this study were E. faecalis American Type Culture Collection 29212, taken from a 4°C stock culture and streaked out twice on brain-heart infusion (BHI) (Scharlau Chemie SA, Barcelona, Spain) agar plates for 24 hours at 37°C. From the subculture of E. faecalis, a 1 McFarland standard suspension was prepared in BHI broth and then diluted 30-fold to obtain an initial bacterial suspension of 1 × 107 colony-forming units (CFUs) per milliliter.

The solutions tested were 2.5% NaOCl

Results

All negative controls showed no bacterial growth. The linear determination coefficient between RLUs and log10 (CFUs + 1) in the groups with positive growth was r2 = 72.8% (r = 0.853) with a P value < .001. Table 1 gives results for luminescence and CFUs. In the NaOCl groups there was no bacterial growth. The ATP readings are consistent with these findings. A similar reduction of RLUs was seen in all NaOCl groups, giving statistically significant differences with respect to the control.

The

Discussion

Culturing techniques are commonly applied to evaluate the antibiofilm efficacy of irrigating solutions in endodontics. The ATP determination may be considered an adequate alternative because it is a rapid means of quantifying bacteria that are viable, even though they do not have the capacity to grow in traditional culture media, hence viable but non-culturable state (17). The bioluminescence ATP assay has sufficient sensitivity in bacteria detection (between 10 and 100 cells) in root canal

Acknowledgments

The authors thank Francisca Castillo Pérez and Gertrudis Gomez Villaescusa for their technical assistance.

This study was supported by the Research Group CTS-167 of the Junta de Andalucía, Spain. This study has been possible by a research initiation fellowship of Plan Propio de investigación de la Universidad de Granada-2016, granted to Carmen Solana, the first author of this paper.

The authors deny any conflicts of interest related to this study.

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