A novel furanone-modified antibacterial dental glass ionomer cement

Exploring the biomedical potential of a novel modified glass ionomer cement against the pandrug-resistant oral pathogen Candida albicans SYN-01

Dental caries is an infectious disease that is a major concern for dentists. Streptococci and Lactobacilli were long thought to be the primary etiology responsible for caries. Candida albicans with acidogenic and aciduric characteristics has recently been implicated in the onset and progression of cariogenic lesions. Moreover, due to the increased resistance to common antimicrobials, the discovery of innovative candidates is in high demand. Therefore, our study might be the first report that explores the efficacy of glass ionomer cement (GIC) incorporated with a newly modified carboxylated chitosan derivative (CS-MC) against multidrug-resistant (MDR) and/or pandrug resistant (PDR) C. albicans isolated from the oral cavity. In this work, four CS-MC-GIC groups with different concentrations were formulated. Group four (CS-MC-GIC-4) gave a significant performance as an anticandidal agent against selected PDR Candida strain, with an obvious decrease in its cell viability and high antibiofilm activity. It also, enhanced all the mechanical properties and supports cell viability of Vero cells as a nontoxic compound. Moreover, CS-MC-GIC-4 inhibited neuraminidases completely, which might provide a novel mechanism to prevent dental/oral infections. Thus, findings in this study open up new prospect of the utilization of CS-MC-GIC as a novel dental filling material against oral drug-resistant Candida.

Hybrid nanolayers of star polymers and silver nanoparticles with antibacterial activity

The aim of this study was to obtain stable star polymer layers with incorporated silver nanoparticles (AgNPs) and to study the antimicrobial activity of these hybrid materials. In this work, a novel approach regarding the synthesis of AgNPs directly by the star polymer layer is presented. Nanolayers of poly(N,N'-dimethylaminoethyl methacrylate) and hydroxyl-bearing poly[oligo(ethylene glycol) methacrylate] (P(DMAEMA-co-OEGMA-OH)) stars, covalently bound with solid supports, were obtained through chemical reaction of hydroxyl groups in the star arms with substrate modified with imidazole derivative. Quantitative chemical composition analysis and tracking of the changes in the morphology and wettability after every step of surface modification confirmed the covalent attachment of stars with the support. In the next step, the polymer nanolayers were modified with AgNPs formed in situ using only amine groups of the star arms and followed by the crystal quartz microbalance (QCM). The analysis of the layer thickness and affinity to water, both with the shape, size and amount of silver incorporated into the layer, confirmed the efficacy of AgNPs formation. The amount of silver incorporated into layers was correlated with the molar masses of the grafted stars, and a possible location of AgNPs within layers was shown. The antibacterial activity tests of prepared nanolayers showed that obtained hybrid materials were highly effective against both gram-positive and gram-negative bacteria strains. This study shows that the obtained layers are promising as stable coatings for antibacterial applications.

Microhardness and Fluoride Release of Glass Ionomer Cement Modified with a Novel Al+3 Complex to Enhance Its Antimicrobial Activity

Objectives

To synthesize and characterize a novel Al⁺³ complex with 2-(2-hydroxyphenyl)-1H-benzimidazole (HL) to be added to a restorative glass ionomer cement (GIC) to enhance its antimicrobial activities and to evaluate the Vickers microhardness (HV) and fluoride release (FR) of the modified GIC.

Materials and Methods

Al⁺³ complex was synthesized by the addition of 1 mmol (0.210 g) of HL to 1 mmol (0.342 g) of aluminum sulfate in ethanol. The resulting solution was then refluxed under stirring for 24 h and then collected by filtration and dried in a vacuum desiccator over an anhydrous CaCl₂. Characterization of Al⁺³ complex was carried out by Fourier transform infrared spectroscopy (FTIR), elemental microanalysis, thermal gravimetric analysis (TGA), molar conductance, ¹H NMR spectra, and electron impact-mass spectrometry. The antimicrobial activity of Al⁺³ complex-modified GIC (Al-GIC) was studied by the “cut plug method” against Gram-negative bacteria (Acinetobacter baumannii) and Gram-positive bacteria (Staphylococcus aureus, Enterococcus, and Streptococcus mutants) and fungi (Candida albicans). HV was evaluated by a digital microhardness tester (Zwick/Roell, Indentec, ZHVμ-S, West Midlands, England). Fluoride levels in ppm were obtained using the ion-selective electrode connected to a digital meter. A one-way ANOVA and Bonferroni test were used to analyze the data with the significance level established at p ≤ 0.05.

Results

Synthesis of Al⁺³ complex was confirmed by FTIR, elemental microanalysis TGA, molar conductance, ¹H NMR spectra, and electron impact-mass spectrometry. Al-GICs exhibited an enhanced antibacterial activity against all studied microorganisms as confirmed by the growth of inhibition zones compared to control GIC (C-GIC). Though there was a slight reduction in HV and FR with increasing the added percent of Al⁺³ complex, no significant differences were found between the studied groups.

Conclusions

Addition of Al⁺³ complex to GIC powder enhanced the antimicrobial activity of GIC materials. As there was a negligible insignificant reduction in HV and FR upon the addition of Al⁺³ complex, Al-GICs can be used with a guaranteed degree of clinical success.

Nanotheranostics: A Possible Solution for Drug-Resistant Staphylococcus aureus and their Biofilms?

Staphylococcus aureus is a notorious pathogen that colonizes implants (orthopedic and breast implants) and wounds with a vicious resistance to antibiotic therapy. Methicillin-resistant S. aureus (MRSA) is a catastrophe mainly restricted to hospitals and emerged to community reservoirs, acquiring resistance and forming biofilms. Treating biofilms is problematic except via implant removal or wound debridement. Nanoparticles (NPs) and nanofibers could combat superbugs and biofilms and rapidly diagnose MRSA. Nanotheranostics combine diagnostics and therapeutics into a single agent. This comprehensive review is interpretative, utilizing mainly recent literature (since 2016) besides the older remarkable studies sourced via Google Scholar and PubMed. We unravel the molecular S. aureus resistance and complex biofilm. The diagnostic properties and detailed antibacterial and antibiofilm NP mechanisms are elucidated in exciting stories. We highlight the challenges of bacterial infections nanotheranostics. Finally, we discuss the literature and provide "three action appraisals". (i) The first appraisal consists of preventive actions (two wings), avoiding unnecessary hospital visits, hand hygiene, and legislations against over-the-counter antibiotics as the general preventive wing. Our second recommended preventive wing includes preventing the adverse side effects of the NPs from resistance and toxicity by establishing standard testing procedures. These standard procedures should provide breakpoints of bacteria's susceptibility to NPs and a thorough toxicological examination of every single batch of synthesized NPs. (ii) The second appraisal includes theranostic actions, using nanotheranostics to diagnose and treat MRSA, such as what we call "multifunctional theranostic nanofibers. (iii) The third action appraisal consists of collaborative actions.

A self-cured glass-ionomer cement with improved antibacterial function and hardness

A novel antimicrobial dental self-cured glass-ionomer cement has been developed and evaluated. Alumina filler particles were covalently coated with an antibacterial polymer and blended into a self-cured glass-ionomer cement formulation. Surface hardness and bacterial viability were used to evaluate the modified cements. Results showed that the modified cements exhibited a significantly enhanced antibacterial activity along with improved surface hardness. Effects of antibacterial moiety content, alumina particle size and loading, and total filler content were investigated. It was found that increasing antibacterial moiety content, particle size and loading, and total filler content generally increased surface hardness. Increasing antibacterial moiety, filler loading and total filler content increased antibacterial activity. On the other hand, increasing particle size showed a negative impact on antibacterial activity. The leaching tests indicate no cytotoxicity produced from the modified cements to both bacteria and 3T3 mouse fibroblast cells.

An antibacterial dental light-cured glass-ionomer cement with improved hardness

An antibacterial dental light-cured glass-ionomer cement has been developed and evaluated. An antibacterial furanone derivative was synthesized and covalently attached onto the surface of alumina filler particles. The formed antibacterial fillers were then mixed into a light-curable glass-ionomer cement formulation. Surface hardness and bacterial viability were used to evaluate the modified cements. Effects of coated furanone moiety content on the modified fillers, modified alumina filler particle size and loading, and total glass filler content were investigated. Results showed that increasing antibacterial furanone content, modified particle size and loading, and total glass filler content generally increased surface hardness. Increasing furanone moiety, filler loading and total filler content increased antibacterial activity. On the other hand, increasing particle size decreased antibacterial activity. The leaching tests indicate that the modified experimental cement showed no leachable antibacterial component to bacteria and cells.

Antibacterial and mechanical properties of arginine-containing glass ionomer cements

OBJECTIVE

The study investigated the effect of incorporating l-arginine (Arg) in a glass ionomer cement (GIC) on its mechanical properties and antibacterial potential.

METHODS

Pre-determined proportions (1%, 2%, and 4% by wt.) of Arg were incorporated in GIC powder; while GIC without Arg served as control. The flexural strength, nanohardness, surface roughness, elemental analysis using SEM-EDX (n = 6) and F/Arg/Ca/Al/Si release in deionized water for 21 days were assessed. The antibacterial potential was evaluated in a multi-species biofilm model with Streptococcus mutans, Streptococcus sanguinis, Streptococcus gordonii, and Lactobacillus acidophilus for 72 h. Real-time qPCR was used to analyse biofilm bacterial concentrations. Propidium monoazide modification of real-time qPCR was performed to quantify viable/dead bacteria. The pH, lactic acid, ADS activity, and H₂O₂ metabolism were measured. Confocal microscopy was used to investigate the biofilm bacterial live/dead cells, density, and thickness.

RESULTS

There was no difference in flexural strength among the different groups (p > 0.05). No significant difference in nanohardness and surface roughness was observed between 4% Arg + GIC and control (p > 0.05). The 4% Arg + GIC showed significantly higher F/Arg/Al/Si release than the other groups (p < 0.05), reduced total bacterial concentration and growth inhibition of viable S. mutans and S. sanguinis (p < 0.05). Lactic acid formation for 4% Arg + GIC was significantly higher than 1% Arg + GIC (p < 0.05). The spent media pH of 4% Arg + GIC was higher than the other groups (p < 0.05), with proportionately lower ammonia and higher H₂O₂ released (p < 0.05).

SIGNIFICANCE

Addition of 4% l-arginine in GIC enhanced its antibacterial activity via a biofilm modulatory effect for microbial homeostasis, with no detrimental effect on its mechanical properties.

Nanolayers of Poly(N,N'-Dimethylaminoethyl Methacrylate) with a Star Topology and Their Antibacterial Activity

In this paper, we focus on the synthesis and characterization of novel stable nanolayers made of star methacrylate polymers. The effect of nanolayer modification on its antibacterial properties was also studied. A covalent immobilization of star poly(N,N'-dimethylaminoethyl methacrylate) (PDMAEMA) to benzophenone functionalized glass or silicon supports was carried out via a "grafting to" approach using UV irradiation. To date, star polymer UV immobilization has never been used for this purpose. The thickness of the resulting nanolayers increased from 30 to 120 nm with the molar mass of the immobilized stars. The successful bonding of star PDMAEMA to the supports was confirmed by surface sensitive quantitative spectroscopic methods. Next, amino groups in the polymer layer were quaternized with bromoethane, and the influence of this modification on the antibacterial properties of the obtained materials was analyzed using a selected reference strain of bacteria. The resulting star nanolayer surfaces exhibited higher antimicrobial activity against Bacillus subtilis ATCC 6633 compared to that of the linear PDMAEMA analogues grafted onto a support. These promising results and the knowledge about the influence of the topology and modification of PDMAEMA layers on their properties may help in searching for new materials for antimicrobial applications in medicine.

An improved dental composite with potent antibacterial function

A new BisGMA-based antibacterial dental composite has been formulated and evaluated. Compressive strength and bacterial viability were utilized to evaluate the formed composites. It was found that the new composite exhibited a significantly enhanced antibacterial function along with improved mechanical and physical properties. The bromine-containing derivative-modified composite was more potent in antibacterial activity than the chlorine-containing composite. The modified composites also exhibited an increase of 30-53% in compressive yield strength, 15-30% in compressive modulus, 15-33% in diametral tensile strength and 6-20% in flexural strength, and a decrease of 57-76% in bacterial viability, 23-37% in water sorption, 8-15% in shrinkage, 8-13% in compressive strength, and similar degree of conversion, than unmodified composite. It appears that this experimental composite may possibly be introduced to dental clinics as an attractive dental restorative due to its improved properties as well as enhanced antibacterial function.

Polyvinylchloride surface with enhanced cell/bacterial adhesion-resistant and antibacterial functions

This study reports synthesis and attachment of a novel antibacterial and hydrophilic polymer onto a polyvinylchloride surface via a simple and mild surface coating technique. The compound 3,4-dichloro-5-hydroxy-2(5H)-furanone was derivatized and copolymerized with N-vinylpyrrolidone. The copolymer was then covalently coated onto polyvinylchloride surface. 3T3 mouse fibroblast cells and bacterium Pseudomonas aeruginosa were used to evaluate surface adhesion and antibacterial activity. Results showed that the polymer-modified polyvinylchloride surface not only exhibited significantly decreased 3T3 fibroblast cell adhesion with a 64–84% reduction but also demonstrated significantly decreased P. aeruginosa adhesion with a 65–84% reduction, as compared to unmodified polyvinylchloride. Furthermore, the modified polyvinylchloride surfaces exhibited significant antibacterial functions by inhibiting P. aeruginosa growth with a 58–80% reduction and killing bacteria, as compared to unmodified polyvinylchloride. These results demonstrate that covalent polymer attachment conferred cell/bacterial adhesion-resistant and antibacterial properties to the polyvinylchloride surface.

Surface modification of polyurethane with a hydrophilic, antibacterial polymer for improved antifouling and antibacterial function

Antimicrobial surface is important for the inhibition of bacteria or biofilm formation on biomaterials. The objective of this study was to immobilize a novel hydrophilic polymer containing the antibacterial moiety onto polyurethane surface via a simple surface coating technology to make the surface not only antibacterial but also antifouling. The compound 3,4-dichloro-5-hydroxy-2(5H)-furanone was derivatized, characterized and incorporated onto polyvinylpyrrolidone containing succinimidyl functional groups, followed by coating onto the polyurethane surface. Contact angle, antibacterial function and protein adsorption of the modified surface were evaluated. The result shows that the modified surface exhibited significantly enhanced hydrophilicity with a 54-65% decrease in contact angle, increased antibacterial activity to Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa with a 24-57% decrease in viability, and reduced human serum albumin adsorption with a 64-70% decrease in adsorption, as compared to the original polyurethane.

Bactericidal and Bioactive Dental Composites

Aim: Antimicrobial and bioactive restorative materials are needed to develop a bacteria free environment and tight bond with the surrounding tissue, preventing the spread of secondary caries and thus extending the lifetime of dental restorations. The characteristic properties of new dental bioactive and antibacterial composites are presented in this work. The new composites have been microstructurally characterized and both long and short term properties have been studied. Methods: The Ag-doped sol-gel derived bioactive glass (Ag-BG) was incorporated into resin composite in concentrations 5, 10, and 15 wt.%, to fabricate new Ag-doped bioactive and antibacterial dental composites (Ag-BGCOMP). The microstructural properties and elemental analysis of the developed Ag-BGCOMP was observed. The total bond strength (TBS) was measured immediately and after long term of immersion in medium using microtensile testing. The capability of Ag-BGCOMPs to form apatite layer on their surface after immersion in Simulated Body Fluid (SBF) as well as the bacteria growth inhibition in a biofilm formed by Streptococcus mutans (S. mutans) were evaluated. Results: Homogeneous distribution of Ag-BG particles into the resin composite was observed microstructurally for all Ag-BGCOMPs. The TBS measurements showed non-statistically significant difference between control samples (Ag-BG 0 wt.%) and Ag-BGCOMP specimens. Moreover, the total bond strength between the surrounding tooth tissue and the material of restoration does not present any statistically significant change for all the cases even after 3 months of immersion in the medium. The bioactivity of the Ag-BGCOMPs was also shown by the formation of a calcium-phosphate layer on the surface of the specimens after immersion in SBF. Antibacterial activity was observed for all Ag-BGCOMPs, statistically significant differences were observed between control samples and Ag-BGCOMPs. Accordingly, the number of dead bacteria in the biofilm found to increase significantly with the increase of Ag-BG concentration in the Ag-BGCOMPs. Conclusions: New resin composites with antibacterial and remineralizing properties have been manufactured. Characterization of these materials provides a rationale for future clinical trials to evaluate clinical benefits and outcomes in comparison with currently used dental materials. Significance: The new developed composites could ultimately prevent restoration failure and could advance patients' wellbeing.

Quaternary ammonium-based biomedical materials: State-of-the-art, toxicological aspects and antimicrobial resistance

Microbial infections affect humans worldwide. Many quaternary ammonium compounds have been synthesized that are not only antibacterial, but also possess antifungal, antiviral and anti-matrix metalloproteinase capabilities. Incorporation of quaternary ammonium moieties into polymers represents one of the most promising strategies for preparation of antimicrobial biomaterials. Various polymerization techniques have been employed to prepare antimicrobial surfaces with quaternary ammonium functionalities; in particular, syntheses involving controlled radical polymerization techniques enable precise control over macromolecular structure, order and functionality. Although recent publications report exciting advances in the biomedical field, some of these technological developments have also been accompanied by potential toxicological and antimicrobial resistance challenges. Recent evidenced-based data on the biomedical applications of antimicrobial quaternary ammonium-containing biomaterials that are based on randomized human clinical trials, the golden standard in contemporary medicinal science, are included in the present review. This should help increase visibility, stimulate debates and spur conversations within a wider scientific community on the implications and plausibility for future developments of quaternary ammonium-based antimicrobial biomaterials.

Chemical, microscopic, and microbiological analysis of a functionalized poly-ether-ether-ketone-embedding antibiofilm compounds

Poly-ether-ether-ketone (PEEK) is currently introduced as an alternative material for orthopedic implants due to its biocompatibility and low elastic modulus compared to titanium. Also, a sulphonation treatment can functionalize PEEK to embed therapeutical substances. The objective of this work was to functionalize a PEEK film to incorporate novel lactam-based antibiofilms compounds. PEEK samples were functionalized by sulphuric acid treatment and then dissolved in dimethylsulfoxide, where lactams were added to be incorporated into the polymer. A dip-coating technique was used to synthesize a thin film on a glass-based substrate. The degree of sulfonation (DS) and the incorporation of lactams into sulphonated PEEK (sPEEK) were analyzed by Fourier transform infrared spectroscopy, nuclear magnetic resonance, thermogravimetric analysis (TGA), and scanning electron microscopy. A DS of 65% was obtained and TGA curves confirmed the presence of SO₃ H and lactams in the sPEEK structure. The growth of Streptococcus mutans biofilm decreased on sPEEK surface containing lactams when compared to sPEEK free of lactams. That indicated the antibiofilm activity of those compounds was maintained after incorporation into sPEEK. Planktonic growth analysis showed no long distant effects of sPEEK containing lactams, indicating that no systemic effects should be expected upon clinical uses of medical devices produced with lactam-treated sPEEK. Results revealed that inclusion of lactams into sPEEK represents a good alternative for the production of biomaterials resistant to bacterial accumulation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 3015-3020, 2016.

Effect of anti-biofilm glass-ionomer cement on Streptococcus mutans biofilms

Dental restorative materials with antimicrobial properties can inhibit bacterial colonization, which may result in a reduction of caries at tooth-filling interaction zones. This study aimed to develop antibacterial glass-ionomer cements (GIC) containing a quaternary ammonium monomer (dimethylaminododecyl methacrylate, DMADDM), and to investigate their effect on material performance and antibacterial properties. Different mass fractions (0, 1.1% and 2.2%) of DMADDM were incorporated into the GIC. The flexure strength, surface charge density, surface roughness and fluoride release were tested. A Streptococcus mutans biofilm model was used. Exopolysaccharides (EPS) staining was used to analyze the inhibitory effect of DMADDM on the biofilm matrix. In addition, biofilm metabolic activity, lactic acid metabolism and the expression of glucosyltransferase genes gtfB, gtfC and gtfD were measured. GIC containing 1.1% and 2.2% DMADDM had flexural strengths matching those of the commercial control (P>0.1). DMADDM was able to increase the surface charge density but reduced surface roughness (P<0.05). The incorporation of 1.1% and 2.2% DMADDM elevated the release of fluoride by the GIC in the first 2 days (P<0.05). The novel DMADDM-modified GIC significantly reduced biofilm metabolic activity (P<0.05) and decreased lactic acid production (P<0.05). The quantitative polymerase chain reaction (qPCR) results showed that the expression of gtfB, gtfC and gtfD decreased when mass fractions of DMADDM increased (P<0.05). EPS staining showed that both the bacteria and EPS in biofilm decreased in the DMADDM groups. The incorporation of DMADDM could modify the properties of GIC to influence the development of S. mutans biofilms. In this study, we investigated the interface properties of antibacterial materials for the first time. GIC containing DMADDM can improve material performance and antibacterial properties and may contribute to the better management of secondary caries.

Restorative materials containing antimicrobial agents: is there evidence for their antimicrobial and anticaries effects? A systematic review

The aim of this systematic literature review was to investigate whether the incorporation of antimicrobial agents into dental restorative materials truly exerts an antimicrobial effect against common cariogenic bacteria (primary outcome), and whether the inclusion of antimicrobial agents is able to prevent caries around restorations (secondary outcome). MEDLINE, via PubMed, was searched for papers published between 1980 and 30 November 2014. A total of 1126 articles were retrieved. After inclusion/exclusion assessment, 147 full text articles were read and included in the review, comprising 130 in vitro, 1 in situ, and 4 in vivo studies, as well as 12 literature reviews. In about 78% of in vitro studies, and in all identified in situ and in vivo studies, a positive antimicrobial effect had been found. However, the anticaries effect had not been tested in any of the selected studies. It was concluded that there is indeed evidence that restorative dental materials containing antimicrobial agents exert an antimicrobial effect, both in laboratory and in clinical studies. However, no evidence has been found regarding the role of these agents in preventing or controlling dental caries, or in preventing caries around restorations.

Telechelic poly(2-oxazoline)s with a biocidal and a polymerizable terminal as collagenase inhibiting additive for long-term active antimicrobial dental materials

Dental repair materials face the problem that the dentin below the composite fillings is actively decomposed by secondary caries and extracellular proteases. To address this problem, poly(2-methyloxazoline) with a biocidal and a polymerizable terminal was explored as additive for a commercial dental adhesive. 2.5 wt% of the additive rendered the adhesive contact-active against Streptococcus mutans and washing with water for 101 d did not diminish this effect. The adhesive with 5 wt% additive kills S. mutans cells in the tubuli of bovine dentin. Further, the additive inhibits bacterial collagenase at 0.5 wt% and reduces activity of MMP-9. Human MMPs bound to dentin are inhibited by 96% in a medium with 5 wt% additive. Moreover, no adverse effect on the enamel/dentine shear bond strength was detected.