Antibacterial activity of a glass ionomer cement doped with copper nanoparticles

The Impact of Nano- and Micro-Silica on the Setting Time and Microhardness of Conventional Glass-Ionomer Cements

The objective of this study was to investigate the effect of the incorporation of 2, 4 or 6 wt% of amorphous nano- or micro-silica (Aerosil® OX 50 or Aeroperl® 300 Pharma (Evonik Operations GmbH, Essen, Germany), respectively) on the net setting time and microhardness of Ketac™ Molar (3M ESPE, St. Paul, MN, USA) and Fuji IX GP® (GC Corporation, Tokyo, Japan) glass-ionomer cements (GICs) (viz. KM and FIX, respectively). Both silica particles were found to cause a non-linear, dose-dependent reduction in setting time that was within the clinically acceptable limits specified in the relevant international standard (ISO 9917-1:2007). The microhardness of KM was statistically unaffected by blending with 2 or 4 wt% nano-silica at all times, whereas 6 wt% addition decreased and increased the surface hardness at 1 and 21 days, respectively. The incorporation of 4 or 6 wt% nano-silica significantly improved the microhardness of FIX at 1, 14 and 21 days, with no change in this property noted for 2 wt% addition. Micro-silica also tended to enhance the microhardness of FIX, at all concentrations and times, to an extent that became statistically significant for all dosages at 21 days. Conversely, 4 and 6 wt% additions of micro-silica markedly decreased the initial 1-day microhardness of KM, and the 21-day sample blended at 4 wt% was the only specimen that demonstrated a significant increase in this property. Scanning electron microscopy indicated that the nano- and micro-silica particles were well distributed throughout the composite structures of both GICs with no evidence of aggregation or zoning. The specific mechanisms of the interaction of inorganic nanoparticles with the constituents of GICs require further understanding, and a lack of international standardization of the determination of microhardness is problematic in this respect.

Copper Materials for Caries Management: A Scoping Review

This study comprehensively reviewed the types, properties and potential applications of copper materials for caries management. Two researchers independently searched English publications using PubMed, Scopus and Web of Science. They screened the titles and abstracts of publications presenting original studies for review. They included 34 publications on copper materials, which were categorized as copper and copper alloy materials (13/34, 38%), copper salt materials (13/34, 38%) and copper oxide materials (8/34, 24%). All reported copper materials inhibited the growth of cariogenic bacteria such as Streptococcus mutans and Candida albicans. The materials could be doped into topical agents, restorative fillers, dental adhesives, drinking water, dental implants, orthodontic appliances, mouthwash and sugar. Most publications (29/34, 83%) were laboratory studies, five (5/34, 14%) were animal studies and only one paper (1/34, 3%) was clinical research. In conclusion, copper and copper alloy materials, copper salt materials and copper oxide materials have an antimicrobial property that inhibits cariogenic bacteria and Candida albicans. These copper materials may be incorporated into dental materials and even drinking water and sugar for caries prevention. Most publications are laboratory studies. Further clinical studies are essential to validate the effectiveness of copper materials in caries prevention.

Antibacterial, UV-Protective, Hydrophobic, Washable, and Heat-Resistant BN-Based Nanoparticle-Coated Textile Fabrics: Experimental and Theoretical Insight

The use of nanoparticles (NPs) to modify the surface of cotton fabric is a promising approach to endowing the material with a set of desirable characteristics that can significantly expand the functionality, wear comfort, and service life of textile products. Herein, two approaches to modifying the surface of hexagonal boron nitride (h-BN) NPs with a hollow core and a smooth surface by treatment with maleic anhydride (MA) and diethylene triamine (DETA) were studied. The DETA and MA absorption on the surface of h-BN and the interaction of surface-modified h-NPs with cellulose as the main component of cotton were modeled using density functional theory with the extended Perdew-Burke-Ernzerhof functional. Theoretical modeling showed that the use of DETA as a binder agent can increase the adhesion strength of BN NPs to textile fabric due to the simultaneous hydrogen bonds with cellulose and BN. Due to the difference in zeta potentials (-38.4 vs -25.8 eV), MA-modified h-BN NPs form a stable suspension, while DETA-modified BN NPs tend to agglomerate. Cotton fabric coated with surface-modified NPs exhibits an excellent wash resistance and high hydrophobicity with a water contact angle of 135° (BN-MA) and 146° (BN-DETA). Compared to the original textile material, treatment with MA- and DETA-modified h-BN NPs increases heat resistance by 10% (BN-MA fabric) and 15% (BN-DETA fabric). Cotton fabrics coated with DETA- and MA-modified BN NPs show enhanced antibacterial activity against Escherichia coli U20 and Staphylococcus aureus strains and completely prevent the formation of an E. coli biofilm. The obtained results are important for the further development of fabrics for sports and medical clothing as well as wound dressings.

Multifunctional Medical Grade Resin with Enhanced Mechanical and Antibacterial Properties: The Effect of Copper Nano-Inclusions in Vat Polymerization (VPP) Additive Manufacturing

Vat photopolymerization (VPP) is an additive manufacturing process commonly used in medical applications. This work aims, for the first time in the literature, to extend and enhance the performance of a commercial medical-grade resin for the VPP process, with the development of nanocomposites, using Copper (Cu) nanoparticles as the additive at two different concentrations. The addition of the Cu nanoparticles was expected to enhance the mechanical properties of the resin and to enable biocidal properties on the nanocomposites since Cu is known for its antibacterial performance. The effect of the Cu concentration was investigated. The nanocomposites were prepared with high-shear stirring. Specimens were 3D printed following international standards for mechanical testing. Their thermal and spectroscopic response was also investigated. The morphological characteristics were examined. The antibacterial performance was evaluated with an agar well diffusion screening process. The experimental results were analyzed with statistical modeling tools with two control parameters (three levels each) and eleven response parameters. Cu enhanced the mechanical properties in all cases studied. 0.5 wt.% Cu nanocomposite showed the highest improvement (approximately 11% in tensile and 10% in flexural strength). The antibacterial performance was sufficient against S. aureus and marginal against E. coli.

Incorporation of Nanomaterials in Glass Ionomer Cements-Recent Developments and Future Perspectives: A Narrative Review

Glass ionomer cements (GICs), restorative materials with commercial availability spanning over five decades, are widely applied due to their advantages (including bio-compatibility, fluoride release, or excellent bonding properties). However, GICs have shortcomings. Among the disadvantages limiting the application of GICs, the poor mechanical properties are the most significant. In order to enhance the mechanical or antimicrobial properties of these materials, the addition of nanomaterials represents a viable approach. The present paper aims to review the literature on the application of different types of nanomaterials for the enhancement of GICs' mechanical and antimicrobial properties, which could lead to several clinical benefits, including better physical properties and the prevention of tooth decay. After applying the described methodology, representative articles published in the time period 2011-present were selected and included in the final review, covering the modification of GICs with metallic nanoparticles (Cu, Ag), metallic and metalloid oxide nanoparticles (TiO₂, ZnO, MgO, Al₂O₃, ZrO₂, SiO₂), apatitic nanomaterials, and other nanomaterials or multi-component nanocomposites.

Copper-containing nanoparticles: Mechanism of antimicrobial effect and application in dentistry-a narrative review

Copper has been used as an antimicrobial agent long time ago. Nowadays, copper-containing nanoparticles (NPs) with antimicrobial properties have been widely used in all aspects of our daily life. Copper-containing NPs may also be incorporated or coated on the surface of dental materials to inhibit oral pathogenic microorganisms. This review aims to detail copper-containing NPs' antimicrobial mechanism, cytotoxic effect and their application in dentistry.

Comparison and Advanced Antimicrobial Strategies of Silver and Copper Nanodrug-Loaded Glass Ionomer Cement against Dental Caries Microbes

Caries lesions during cement repairs are a severe issue, and developing a unique antimicrobial restorative biomaterial can help to reduce necrotic lesion recurrence. As a result, Thymus vulgaris extract was used to biosynthesize copper nanoparticles (TVE-CuNPs) exhibiting different characteristics (TVE). Along with TVE-CuNPs, commercial silver nanoparticles (AgNPs) and metronidazole were combined with glass ionomer cement (GIC) to test its antibacterial efficacy and compressive strength. FTIR, XRD, UV-Vis spectrophotometry, and TEM were applied to characterize the TVE-CuNPs. Additionally, AgNPs and TVE-CuNPs were also combined with metronidazole and GIC. The modified GIC samples were divided into six groups, where groups 1 and 2 included conventional GIC and GIC with 1.5% metromidazole, respectively; group 3 had GIC with 0.5% TVE-CuNPs, while group 4 had 0.5% TVE-CuNPs with metronidazole in 1.5%; group 5 had GIC with 0.5% AgNPs, and group 6 had 0.5% AgNPs with metronidazole at 1.5%. An antimicrobial test was performed against Staphylococcus aureus (S. aureus) and Streptococcus mutans (S. mutans) by the disc diffusion method and the modified direct contact test (MDCT). GIC groups 4 and 6 demonstrated a greater antimicrobial efficiency against the two tested strains than the other groups. In GIC groups 4 and 6, the combination of GIC with two antimicrobial agents, 1.5% metronidazole and 0.5% TVE-CuNPs or AgNPs, enhanced the antimicrobial efficiency when compared to that of the other groups with or without a single agent. GIC group specimens combined with nanosilver and nanocopper had similar mean compressive strengths when compared to the other GIC groups. Finally, the better antimicrobial efficacy of GIC boosted by metronidazole and the tested nanoparticles against the tested strains may be relevant for the future creation of more efficient and modified restorations to reduce dental caries lesions.

Application of Copper Nanoparticles in Dentistry

Nanoparticles based on metal and metallic oxides have become a novel trend for dental applications. Metal nanoparticles are commonly used in dentistry for their exclusive shape-dependent properties, including their variable nano-sizes and forms, unique distribution, and large surface-area-to-volume ratio. These properties enhance the bio-physio-chemical functionalization, antimicrobial activity, and biocompatibility of the nanoparticles. Copper is an earth-abundant inexpensive metal, and its nanoparticle synthesis is cost effective. Copper nanoparticles readily intermix and bind with other metals, ceramics, and polymers, and they exhibit physiochemical stability in the compounds. Hence, copper nanoparticles are among the commonly used metal nanoparticles in dentistry. Copper nanoparticles have been used to enhance the physical and chemical properties of various dental materials, such as dental amalgam, restorative cements, adhesives, resins, endodontic-irrigation solutions, obturation materials, dental implants, and orthodontic archwires and brackets. The objective of this review is to provide an overview of copper nanoparticles and their applications in dentistry.

Novel composite cement containing the anti-microbial compound CPC-Montmorillonite

OBJECTIVES

The aim of this study was to evaluate the mechanical properties, bonding performance and anti-microbial activity of a novel composite cement containing cetylpyridinium chloride (CPC) modified montmorillonite ('CPC-Mont'), and using these parameters to determine the optimal particle size and concentration of CPC-Mont the composite cement can be loaded with.

METHODS

CPC-Mont particles with a median diameter of 30 and 7 µm were prepared and added to a composite cement at a concentration of 2, 3, 4, 5 and 7.5 wt%. Mechanical properties and bonding performance of the experimental composite cements were evaluated by 3-point bending and micro-tensile bond-strength testing. The amount of CPC released from the cement disks was quantified using a UV-vis recording spectrophotometer. The anti-biofilm activity was studied using scanning electron microscopy (SEM).

RESULTS

Adding 30-μm CPC-Mont decreased the mechanical properties and bonding performance of the composite cement, while no reduction was observed for the 7-μm CPC-Mont loaded cement formulation. Although CPC release substantially decreased during the 7-day period assessed, 5- and 7.5-wt% CPC-Mont loaded composite cement inhibited biofilm formation for 30 days.

SIGNIFICANCE

Loading composite cement with CPC-Mont with a median diameter of 7 µm at concentrations of 5-7.5 wt% was effective in achieving continuous anti-biofilm activity, while maintaining mechanical strength and bonding performance.

Mechanical, antibacterial, biocompatible and microleakage evaluation of glass ionomer cement modified by nanohydroxyapatite/polyhexamethylene biguanide

This study aims to look for the best concentration of nanohydroxyapatite (NHA) and polyhexamethylene biguanide (PHMB) incorporated into glass ionomer cement (GIC) in accordance with ISO:9917-1 and evaluate its mechanical, antibacterial, biocompatible and microleakages properties. NHA was incorporated into Fuji Ⅱ GIC powder at 0-8.00 wt% concentration and specimens were prepared; the best concentration was sifted out according to ISO9917-1. Based on best NHA proportion, 0-0.80% PHMB was dispersed into powder and samples were respectively prepared. Mechanical properties include net setting time (ST), compressive strength (CS), microhardness (VNH), solubility and scanning electron microscopy (SEM) observation. Those met ISO standard were qualified to continue microleakage observation, antibacterial activity, and biocompatibility test. The results suggested that GIC/6%NHA/0.2% PHMB and GIC/6%NHA/0.4%PHMB showed great performances in mechanical, antibacterial, and microleakage improvements, and the cytotoxicity of modified GIC showed no statistical difference with pure GIC.

Zinc Oxide and Copper Chitosan Composite Films with Antimicrobial Activity

The role of the oral microbiome and its effect on dental diseases is gaining interest. Therefore, it has been sought to decrease the bacterial load to fight oral cavity diseases. In this study, composite materials based on chitosan, chitosan crosslinked with glutaraldehyde, chitosan with zinc oxide particles, and chitosan with copper nanoparticles were prepared in the form of thin films, to evaluate a new alternative with a more significant impact on the oral cavity bacteria. The chemical structures and physical properties of the films were characterized using by Fourier transform infrared spectroscopy (FTIR,) Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), elemental analysis (EDX), thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), and contact angle measurements. Subsequently, the antimicrobial activity of each material was evaluated by agar diffusion tests. No differences were found in the hydrophilicity of the films with the incorporation of ZnO or copper particles. Antimicrobial activity was found against S. aureus in the chitosan film crosslinked with glutaraldehyde, but not in the other compositions. In contrast antimicrobial activity against S. typhimurium was found in all films. Based on the data of present investigation, chitosan composite films could be an option for the control of microorganisms with potential applications in various fields, such as medical and food industry.

Effect of Nanostructures on the Properties of Glass Ionomer Dental Restoratives/Cements: A Comprehensive Narrative Review

Overall perspective of nanotechnology and reinforcement of dental biomaterials by nanoparticles has been reported in the literature. However, the literature regarding the reinforcement of dental biomaterials after incorporating various nanostructures is sparse. The present review addresses current developments of glass ionomer cements (GICs) after incorporating various metallic, polymeric, inorganic and carbon-based nanostructures. In addition, types, applications, and implications of various nanostructures incorporated in GICs are discussed. Most of the attempts by researchers are based on the laboratory-based studies; hence, it warrants long-term clinical trials to aid the development of suitable materials for the load bearing posterior dentition. Nevertheless, a few meaningful conclusions are drawn from this substantial piece of work; they are as follows: (1) most of the nanostructures are likely to enhance the mechanical strength of GICs; (2) certain nanostructures improve the antibacterial activity of GICs against the cariogenic bacteria; (3) clinical translation of these promising outcomes are completely missing, and (4) the nanostructured modified GICs could perform better than their conventional counterparts in the load bearing posterior dentition.

Analysis of Chlorhexidine Modified Cement in Orthodontic Patients: A Double-Blinded, Randomized, Controlled Trial

OBJECTIVES

The aim of this study was to evaluate the microbiological and mechanical properties of glass ionomer cement (GIC) modified by chlorhexidine (CLX) for the purpose of cementing bands to the teeth of orthodontic patients.

MATERIALS AND METHODS

Ten patients, between the ages of 19 and 33 years, in the initial stage of orthodontic treatment, were randomly designated to two groups using the split-mouth design (n = 10). One group (GICEX) had bands cemented with GIC modified by CLX and a Control group (GIC), evaluated at time intervals before (T0), 3 months (T3), and 6 months (T6) after cementation. Total microbiological counts were performed, and color stability of tooth enamel, salivary pH, and the adhesive remnant index (ARI) were evaluated.

STATISTICAL ANALYSIS

The Friedman and Dunn's tests, Mann-Whitney, one-way analysis of variance, and Tukey, and paired and non-paired t-tests (p< 0.05) were used.

RESULTS

In T3, there was evidence of significant reduction in the quantity of colony forming unit (CFU) in GICEX group in comparison with the Control (p = 0.041). In T6, the quantity of CFU was similar to the quantity in T3 and significantly different to control (p = 0.045); Control group demonstrated a similar quantity of CFU between the experimental time intervals (p = 0.066). Salivary pH demonstrated significant difference only between the time intervals T0 and T6 (p = 0.022). The tooth enamel color (p = 0.366) and ARI (p = 0.343) values demonstrated no significant changes.

CONCLUSION

The incorporation of CLX into GIC demonstrated effective antibacterial action, allowed a good bond of the cement to the enamel, a high rate of survival of the bands, did not change the color of the tooth enamel, and maintained the salivary pH at physiological levels.