Ex vivoantimicrobial efficacy of strong acid electrolytic water againstEnterococcus faecalisbiofilm

Electrolysed oxidising water as a multi-purpose biocide in dental healthcare-A scoping review

OBJECTIVES

The objective of this scoping review was to map evidence of electrolysed oxidising water (EOW) as a biocide for dental applications of relevance to older people and identify research gaps.

BACKGROUND

EOW is an emerging, "green," and cost-effective biocide. There are no reviews on the landscape of EOW research as either an antiseptic or disinfectant in dental healthcare or its suitability for the oral healthcare of older people.

MATERIALS AND METHODS

The review follows the PRISMA Extension for Scoping Reviews (PRISMA-ScR) guidelines. Database searches (Google Scholar, PubMed, Web of Science, Ovid, Scopus and Science Direct) were undertaken using MESH terms and Boolean operators with no date restrictions, to identify full-text, original reports published in English-language peer-reviewed journals.

RESULTS

The search yielded 114 papers that met the inclusion/exclusion criteria. Dental applications of EOW include its use as an endodontic irrigant (39%); mouth rinse/surgical irrigant (21%); disinfectant for dental unit water lines (19%) and dental biomaterials (17%); and for antimicrobial efficacy, effects on oral tissues and on dental material properties. Most studies (83%) evaluated a single EOW formulation (acidic, moderately acidic or neutral) that was either generated at 'point-of-use' (POU; 72%), bottled ('ready-to-use', RTU; 24%) or from unspecified (3%) sources. Six reports evaluated storage-related parameters and 25 evaluated clinical applications; 89 were in vitro studies and one investigated the cost-effectiveness of POU EOW.

CONCLUSIONS

Neutral-pH, EOW is effective as an antimicrobial agent without deleterious effects on oral tissues. However, research on the impact of storage conditions, anti-Candida biofilm efficacy and mechanism of action against yeasts, long-term effects on denture materials and cost-effectiveness is required to establish the suitability of EOW as a multipurpose biocide for dental healthcare, including infection-control requirements relating to older people.

Model system parameters influence the sodium hypochlorite susceptibility of endodontic biofilms

AIM

To evaluate in a laboratory setting the influence of several model system parameters on the sodium hypochlorite (NaOCl) susceptibility of endodontic biofilms. Based on these findings, a relevant in vitro endodontic biofilm model is proposed.

METHODOLOGY

In vitro biofilms were cultured, varying the following experimental model parameters: biofilm composition (monospecies Enterococcus faecalis and a multispecies biofilm including E. faecalis, Fusobacterium nucleatum, Prevotella intermedia and Porphyromonas gingivalis), incubation time (24 h or 11 days), incubation atmosphere (aerobically or anaerobically) and biofilm substrate (polystyrene microtiter plate wells, hydroxyapatite or dentine). Biofilms were subjected to treatment with NaOCl (0.025%, 0.1%, 0.5%, 2.5%) for 1 min, control groups included treatment with purified water. Biofilms were harvested and the number of surviving cells was determined by plate counting using general (monospecies biofilms) or selective (multispecies biofilms) media. A two-way ANOVA was used to explore the effect of the model parameters on biofilm eradication. Finally, the most physiologically relevant biofilm model (11-day-old multispecies biofilm grown anaerobically on dentine discs) was characterized by selective media plate counting, NaOCl susceptibility testing, scanning and transmission electron microscopy.

RESULTS

There was no difference in NaOCl eradication between the anaerobically and aerobically grown E. faecalis biofilms. One-day-old biofilms of E. faecalis were more susceptible to most tested NaOCl concentrations than 11-day-old biofilms (p < .05). When grown in a multispecies biofilm, E. faecalis was significantly less susceptible to NaOCl treatment than in a monospecies biofilm (p < .05). E. faecalis in a multispecies biofilm grown in a MTP was more susceptible to NaOCl (0.025% and 0.1%) than when grown on hydroxyapatite or dentine. No difference in biofilm NaOCl susceptibility was seen between hydroxyapatite and dentine. The multispecies biofilm proved to be a reproducible model with high NaOCl resistance, complex structure and organization.

CONCLUSION

The parameters biofilm age, biofilm composition and substrate had a significant influence on the NaOCl susceptibility of E. faecalis biofilms. Older biofilms, multispecies biofilms and biofilms grown on dentine and hydroxyapatite had reduced NaOCl susceptibility. These findings emphasize the importance of selecting relevant parameters when designing a laboratory biofilm model system for the evaluation of antimicrobial treatments.

In vitro antimicrobial activity of different electrochemically-activated solutions on enterococcus faecalis

Purpose

The aim of this in vitro study was to assess and compare the antimicrobial efficacy of different electrochemically-activated solutions (ECA) and contemporary irrigants, in root canals infected with Enterococcus faecalis, used with or without EndoActivator (EA).

Materials and methods

A hundred single-rooted human teeth were prepared. Ninety of the root segments were infected with E. faecalis for four weeks, and divided into eight test groups (n = 10) (four with and four without EA sonication) and a positive control (n = 10). The irrigants tested were electrochemically-activated solutions produced by the Medilox® (ECA-MX) and Envirolyte® devices (ECA-EN), 2% CHX and 2.5% NaOCl. The root specimens were irrigated with 5 mL of the test solution, with additional sonic agitation applied to the EA groups. The dentine samples that were obtained from the walls were cultured, and the antibacterial efficacy was evaluated by counting the colony-forming units.

Results

The ECA-EN, 2.5% NaOCl and 2% CHX were more effective than the ECA-MX (p<0.05) with the addition of EA sonication, showing no statistical difference in the elimination of E. faecalis.

Conclusion

The ECA-EN shows potential as an endodontic irrigant, while EA usage gives no benefit in reducing bacteria from root canals.

The Efficacy of an Electrolysed Water Formulation on Biofilms

Electrolysed water is a basic process whereby an electric current is passed through deionised water containing a low concentration of sodium chloride in an electrolysis chamber, which results in a more complex chemistry resulting in the production of a strong bactericidal and fungicidal solution at the anode. This microbicidal solution contains hypochlorous acid that is fast-acting and environmentally safe, as upon bacterial killing, the equilibrium shifts from hypochlorous acid back to salt and water. Other antimicrobial agents produced in this process include sodium hypochlorite and chlorine. The use of electrolysed water formulations in wound care to control wound bioburden is underway. However, there is limited evidence of the efficacy of electrolysed water on the control of biofilms, which are renowned for their tolerance to a variety of antimicrobials. Therefore this study aimed to assess a new electrolysed water formulation on in vitro Staphylococcus aureus and Pseudomonas aeruginosa biofilms. Results showed that the electrolysed water formulation effectively reduced biofilm in all models following a 15 min contact time. Microbial cell counts confirmed the reduction biofilm bacteria. Additional cytotoxicity using L929 fibroblasts confirmed that a 50% and 25% dilution of the electrolysed water formulation was non-cytotoxic to cells. In conclusion, this study has confirmed that the application of a new electrolysed water product effectively removed biofilm after a short exposure time. The use of this technology as a wound cleanser may help to control existing biofilms in complicated, non-healing wounds.

Bactericidal Effect of Strong Acid Electrolyzed Water against Flow Enterococcus faecalis Biofilms

INTRODUCTION

This study evaluated the bactericidal effect of strong acid electrolyzed water (SAEW) against flow Enterococcus faecalis biofilm and its potential application as a root canal irrigant.

METHODS

Flow E. faecalis biofilms were generated under a constant shear flow in a microfluidic system. For comparison, static E. faecalis biofilms were generated under a static condition on coverslip surfaces. Both the flow and static E. faecalis biofilms were treated with SAEW. Sodium hypochlorite (NaOCl, 5.25%) and normal saline (0.9%) were included as the controls. Bacterial reductions were evaluated using confocal laser scanning microscopy and the cell count method. Morphological changes of bacterial cells were observed using scanning electron microscopy.

RESULTS

The confocal laser scanning microscopic and cell count results showed that SAEW had a bactericidal effect similar to that of 5.25% NaOCl against both the flow and static E. faecalis biofilms. The scanning electron microscopic results showed that smooth, consecutive, and bright bacteria surfaces became rough, shrunken, and even lysed after treated with SAEW, similar to those in the NaOCl group.

CONCLUSIONS

SAEW had an effective bactericidal effect against both the flow and static E. faecalis biofilms, and it might be qualified as a root canal irrigant for effective root canal disinfection.

Effects of ciprofloxacin-containing scaffolds on enterococcus faecalis biofilms

INTRODUCTION

Antibiotic-containing polymer-based nanofibers (hereafter referred to as scaffolds) have demonstrated great potential for their use in regenerative endodontics from both an antimicrobial and cytocompatibility perspective. This study sought to evaluate in vitro the effects of ciprofloxacin (CIP)-containing polymer scaffolds against Enterococcus faecalis biofilms.

METHODS

Human mandibular incisors were longitudinally sectioned to prepare radicular dentin specimens. Sterile dentin specimens were distributed in 24-well plates and inoculated with E. faecalis for biofilm formation. Infected dentin specimens were exposed to 3 groups of scaffolds, namely polydioxanone (PDS) (control), PDS + 5 wt% CIP, and PDS + 25 wt% CIP for 2 days. Colony-forming units (CFU/mL) (n = 10) and scanning electron microscopy (SEM) (n = 2) were performed to quantitatively and qualitatively assess the antimicrobial effectiveness, respectively.

RESULTS

PDS scaffold containing CIP at 25 wt% showed maximum bacteria elimination with no microbial growth, differing statistically (P < .05) from the control (PDS) and from PDS scaffold containing CIP at 5 wt%. Statistical differences (P < .05) were also seen for the CFU/mL data between pure PDS (5.92-6.02 log CFU/mL) and the PDS scaffold containing CIP at 5 wt% (5.39-5.87 log CFU/mL). SEM images revealed a greater concentration of bacteria on the middle third of the dentin specimen after 5 days of biofilm formation. On scaffold exposures, SEM images showed similar results when compared with the CFU/mL data. Dentin specimens exposed to PDS + 25 wt% CIP scaffolds displayed a practically bacteria-free surface.

CONCLUSIONS

On the basis of the data presented, newly developed antibiotic-containing electrospun scaffolds hold promise as an intracanal medicament to eliminate biofilm/infection before regenerative procedures.