Endodontics
Efficacy of chlorhexidine- and calcium hydroxide–containing medicaments against Enterococcus faecalis in vitro

https://doi.org/10.1016/S1079-2104(03)00166-5Get rights and content

Abstract

Objective

We sought to assess the efficacy of chlorhexidine (CHX) and calcium hydroxide, Ca(OH)2, against Enterococcus faecalis in vitro.

Study design

The effect of CHX (0.2% and 2% in gel or solution) and Ca(OH)2 (alone or with 0.2% CHX gel) was evaluated by using the agar diffusion test and an in vitro human root inoculation method, to measure zone of inhibition or bacterial growth with optical density analysis, respectively. For optical density analysis, samples from infected root canals were collected after 7 days of medication and were cultured for 24 hours in brain-heart infusion to detect viable bacteria.

Results

In the agar diffusion test, CHX was effective against E faecalis in a concentration-dependent fashion, but Ca(OH)2 alone had no effect. In the root canal inoculation test, CHX was significantly more effective against E faecalis than Ca(OH)2 was (P < .05), but there were no significant differences between the modes of medication or concentrations of CHX.

Conclusions

CHX is effective against E faecalis in vitro. Further in vivo studies are needed to confirm the value of CHX in clinical treatment.

Section snippets

Agar diffusion test

E faecalis (ATCC 292121) and Streptococcus mutans (NG8) were grown overnight in brain-heart infusion (BHI) broth (Difco Laboratories, Baltimore, Md), adjusted to a 0.5 turbidity reading on the McFarland scale (1.5 × 108 bacteria/mL), and inoculated in BHI agar plates. Inoculation was performed by using sterile pipettes brushed across the media.27 Round wells, 5 mm deep and 6 mm in diameter, were punched in the cultivated agar plates and filled with one of the test medicaments or controls. The

Agar diffusion test

Excluding the control groups, there was a very significant correlation between the zones of inhibition against E faecalis and S mutans (r = .930; P < .001). S mutans was inhibited by all the medicaments, and E faecalis was inhibited by all the CHX-containing medicaments (Fig 2). For all the medicaments, S mutans was inhibited significantly better than E faecalis was (P < .05). Neither control group demonstrated any inhibitory effect against either bacteria (data not shown).

In the

Discussion

The experimental model used in this study was adapted from that established by Ørstavik and Haapasalo15 for infection and disinfection of dentinal tubules. As in our previous study,26 the model was adapted for extracted human teeth rather than bovine incisors. This modification was considered appropriate because of the marked difference in diameter between the canals of bovine and human teeth and thus in the volume of medicament that can be placed in these canals.

E faecalis was chosen for the

Acknowledgements

We thank Dr Dennis Cvitkovitch and Mrs Kristen Krastel for their valuable support in conducting the microbiologic procedures of this study.

Assistant Professor and Head, Endodontic Division, Department of Dental Clinical Sciences, Dalhousie University, Halifax, Nova Scotia, Canada

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    Assistant Professor and Head, Endodontic Division, Department of Dental Clinical Sciences, Dalhousie University, Halifax, Nova Scotia, Canada

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    Assistant Professor, Department of Endodontics, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada

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    Assistant Professor, Department of Community Dentistry, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada

    Professor and Head, Department of Endodontics. Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada

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