Antibacterial effect of silver diamine fluoride and potassium iodide against E. faecalis, A. naeslundii and P. micra

Antibacterial Properties of the Antimicrobial Peptide Gallic Acid-Polyphemusin I (GAPI)

A novel antimicrobial peptide, GAPI, has been developed recently by grafting gallic acid (GA) to polyphemusin I (PI). The objective of this study was to investigate the antibacterial effects of GAPI on common oral pathogens. This laboratory study used minimum inhibitory concentrations and minimum bactericidal concentrations to assess the antimicrobial properties of GAPI against common oral pathogens. Transmission electron microscopy was used to examine the bacterial morphology both before and after GAPI treatment. The results showed that the minimum inhibitory concentration ranged from 20 μM (Lactobacillus rhamnosus) to 320 μM (Porphyromonas gingivalis), whereas the minimum bactericidal concentration ranged from 80 μM (Lactobacillus acidophilus) to 640 μM (Actinomyces naeslundii, Enterococcus faecalis, and Porphyromonas gingivalis). Transmission electron microscopy showed abnormal curvature of cell membranes, irregular cell shapes, leakage of cytoplasmic content, and disruption of cytoplasmic membranes and cell walls. In conclusion, the GAPI antimicrobial peptide is antibacterial to common oral pathogens, with the potential to be used to manage oral infections.

Antimicrobial Efficacy of Silver Diamine Fluoride against Enterococcus faecalis: A Systematic Review of In Vitro Studies

Introduction/Objectives. Enterococcus faecalis has been implicated in infections of treated root canals. Current irrigants and intracanal medicaments cannot eliminate E. faecalis completely from the root canal. Silver diamine fluoride (SDF) prevents caries by promoting remineralization and exerting an antibacterial effect. Studies suggest that SDF may possess antibacterial properties against E. faecalis. The purpose of this review is to systematically and critically analyze the literature, focusing on the use of SDF as an intracanal medicament or irrigant, when compared to other antibacterial agents. Data/Sources. The focused question was "Is the antibacterial effect of SDF against E. faecalis better than other intracanal medicaments and irrigants?" Using the keywords ((silver diamine fluoride) AND (Enterococcus faecalis)) AND ((sodium hypochlorite) OR (NaOCl) OR (chlorhexidine) OR (calcium hydroxide) OR (Ca(OH)₂)), an electronic search was conducted on the following databases: PubMed/MEDLINE, ISI Web of Science, Scopus, EMBASE, and Google Scholar. The clinical trial registers ClinicalTrials.gov and CONTROL were also searched using the same keywords. General characteristics and outcomes were extracted, and quality of the studies was assessed using the Preferred Reporting Items for Laboratory studies in Endodontology (PRILE) guidelines. Study Selection. Six articles (five in vitro studies and one ex vivo study) were included in this systematic review. In the majority of the studies, SDF had equal or better antibacterial efficacy against E. faecalis compared to calcium hydroxide, sodium hypochlorite, and chlorhexidine. However, the majority of the studies did not fulfill several items in the PRILE criteria and had numerous sources of bias. Conclusions. Within the limitations of the systematic review and the studies reviewed, SDF may be effective against E. faecalis and therefore could be used as an intracanal medicament and/or irrigant to prevent reinfections of the root canals and improve the outcomes of endodontic treatment. However, animal and clinical studies should be carried out to determine the efficacy of SDF in endodontics. Trial Registration. The protocol for this review was registered on PROSPERO. Registration number: CRD42021224741.

Recent Advances in the Development of Lipid-, Metal-, Carbon-, and Polymer-Based Nanomaterials for Antibacterial Applications

Infections caused by multidrug-resistant (MDR) bacteria are becoming a serious threat to public health worldwide. With an ever-reducing pipeline of last-resort drugs further complicating the current dire situation arising due to antibiotic resistance, there has never been a greater urgency to attempt to discover potential new antibiotics. The use of nanotechnology, encompassing a broad range of organic and inorganic nanomaterials, offers promising solutions. Organic nanomaterials, including lipid-, polymer-, and carbon-based nanomaterials, have inherent antibacterial activity or can act as nanocarriers in delivering antibacterial agents. Nanocarriers, owing to the protection and enhanced bioavailability of the encapsulated drugs, have the ability to enable an increased concentration of a drug to be delivered to an infected site and reduce the associated toxicity elsewhere. On the other hand, inorganic metal-based nanomaterials exhibit multivalent antibacterial mechanisms that combat MDR bacteria effectively and reduce the occurrence of bacterial resistance. These nanomaterials have great potential for the prevention and treatment of MDR bacterial infection. Recent advances in the field of nanotechnology are enabling researchers to utilize nanomaterial building blocks in intriguing ways to create multi-functional nanocomposite materials. These nanocomposite materials, formed by lipid-, polymer-, carbon-, and metal-based nanomaterial building blocks, have opened a new avenue for researchers due to the unprecedented physiochemical properties and enhanced antibacterial activities being observed when compared to their mono-constituent parts. This review covers the latest advances of nanotechnologies used in the design and development of nano- and nanocomposite materials to fight MDR bacteria with different purposes. Our aim is to discuss and summarize these recently established nanomaterials and the respective nanocomposites, their current application, and challenges for use in applications treating MDR bacteria. In addition, we discuss the prospects for antimicrobial nanomaterials and look forward to further develop these materials, emphasizing their potential for clinical translation.

Antibacterial efficacy of peracetic acid in comparison with sodium hypochlorite or chlorhexidine against Enterococcus faecalis and Parvimonas micra

Background

The main goal of an endodontic treatment is a complete debridement of the root canal system; however, currently mechanical shaping and chemical cleaning procedures for this purpose have deemed non-satisfactory.

Methods

The efficacy of peracetic acid (PAA; 0.5, 1.0, 2.0%), as a root canal irrigation solution, against Enterococcus faecalis (DSM 20478) and Parvimonas micra (DSM 20468) when compared with the one of sodium hypochlorite (NaOCI; 1.0, 3.0, 5.0%), chlorhexidine digluconate (CHX; 0.12, 0.2, 2.0%) and 0.9% NaCI (as a control solution) was in vitro investigated with the agar diffusion and direct contact methods. The inhibition zone diameters observed with the agar diffusion test were determined. The viable bacterial counts (CFU/ml) were calculated with the direct method.

Results

The agar diffusion test showed that all three root canal irrigation solutions had an efficacy against E. faecalis at all concentrations. The largest inhibition zone diameters against E. faecalis were observed with 5.0% NaOCI. At all three concentrations of PAA, NaOCI, and CHX, the inhibition zone diameter increased with increase in concentration. For P. micra, PAA had a similar inhibition zone diameter despite a concentration increase. In contrast, for NaOCI and CHX, the inhibition zone diameter increased with increasing concentration. 2.0% CHX produced the largest inhibition zone diameter against P. micra. For E. faecalis, only the comparison between 2.0% PAA and 5.0% NaOCI showed statistical significance (p = 0.004). For P. micra the efficacy comparison between the lowest, middle, and highest concentrations of each solution, a statistical significance (p < 0.05) was found for all three solutions. After direct contact with PAA, NaOCI and CHX, no viable bacteria could be determined for either P. micra or E. faecalis.

Conclusions

PAA had a similar antibacterial efficacy as the one of NaOCl and CHX when in direct contact with E. faecalis and P. micra. In the agar diffusion test, PAA showed a similar antibacterial efficacy as the one of CHX and a lower one as the one of NaOCl for E. faecalis.

Effect of Different Intracanal Medicaments on the Viability and Survival of Dental Pulp Stem Cells

Background: Stem cells play an important role in the success of regenerative endodontic procedures. They are affected by the presence of medicaments that are used before the induction of bleeding or the creation of a scaffold for endodontic regeneration. This study examines the effects of different intracanal medicaments on the viability and survival of dental pulp stem cells at different doses and over different exposure times. Methods: Dental pulp stem cells were cultured from healthy third molar teeth using the long-term explant culture method and characterized using flow cytometry and exposed to different concentrations of calcium hydroxide, doxycycline, potassium iodide, triamcinolone, and glutaraldehyde, each ranging from 0 (control) to 1000 µg/mL. Exposure times were 6, 24, and 48 h. Cell viability was measured using the MTT assay, and apoptosis was measured using the Annexin V-binding assay. Results: All medicaments significantly reduced cell viability at different concentrations over different exposure times. Calcium hydroxide and triamcinolone favored cell viability at higher concentrations during all exposure times compared to other medicaments. The apoptosis assay showed a significant increase in cell death on exposure to doxycycline, potassium iodide, and glutaraldehyde. Conclusion: The intracanal medicaments examined in our study affected the viability of dental pulp stem cells in a time and dose-dependent manner. They also adversely affected the survival of dental pulp stem cells. Further studies are needed to better understand the effect of prolonged exposure to medicaments according to clinical protocols and their effect on the stemness of dental pulp stem cells.