Effects of Magnesium Oxide Nanoparticles Incorporation on Shear Bond Strength and Antibacterial Activity of an Orthodontic Composite: An In Vitro Study

Biogenic Synthesis of Photosensitive Magnesium Oxide Nanoparticles Using Citron Waste Peel Extract and Evaluation of Their Antibacterial and Anticarcinogenic Potential

Background

Magnesium oxide nanoparticles (MgONPs) have been fabricated by several approaches, including green chemistry approach due to diverse application and versatile features.

Objectives

The current study aimed to prepare a convenient, biocompatible, and economically viable MgONPs using waste citron peel extract (CP-MgONPs) to evaluate their biological applications.

Methods

The CP-MgONPs were synthesized by a sustainable approach from extract of waste citron peel both as capping and reducing agents without use of any hazardous material. The physicochemical features of formed CP-MgONPs were determined by sophisticated analytical and microscopic techniques. The biogenic CP-MgONPs were examined for their antibacterial, anticarcinogenic, and photocatalytic attributes.

Results

A prominent absorption peak in the UV-Vis spectra at 284 nm was the distinguishing characteristic of the CP-MgONPs. The scanning electron microscopy (SEM) reveals polyhedral morphology of nanoparticles with slight agglomeration of CP-MgONPs. The CP-MgONPs exerted excellent antibacterial potencies against six bacterial strains. The CP-MgONPs displayed significant susceptibility towards E. coli (20.72 ± 0.33 mm) and S. aureus (19.52 ± 0.05 mm) with the highest inhibition zones. The anticancer effect of CP-MgONPs was evaluated against HepG2 (IC50 : 15.3 μg·mL-1) cancer cells and exhibited potential anticancer activity. A prompt inversion of cellular injury manifested as impairment of the integrity of the cell membrane, apoptosis, and oxidative stress was observed in treated cells with CP-MgONPs. The biosynthesized CP-MgONPs also conducted successful photocatalytic potential as much as MgO powder under the UV-light using acid orange 8 (AO-8) dye. The degradation performance of CP-MgONPs showed over 94% photocatalytic degradation efficiency of acid orange 8 (AO-8) dyes within a short time.

Conclusions

Outcomes of this research signify that biogenic CP-MgONPs may be advantageous at low concentrations, with positive environmental impacts.

Antibacterial Agents for Composite Resin Restorative Materials: Current Knowledge and Future Prospects

Resin composites became the material of choice for direct restorations in anterior and posterior teeth. Despite the revolutionary improvement in the material, restoration failure is still a major drawback due to the material's inherent negative properties, including a lack of antibacterial effects. Therefore, many attempts have been made to incorporate antibacterial agents into resin composite materials to improve their antimicrobial properties and prevent secondary caries formation. Multiple laboratory studies have been conducted using different antibacterial agents, such as quaternary ammonium compounds, methacryloyloxydodecylpyridinium bromide, magnesium oxide nanoparticles, chlorhexidine, and chitosan. This review provides a glance at the current status of these materials and the research directions needed in the future.

Iron and Magnesium Co-substituted Hydroxyapatite Nanoparticles in Orthodontic Composite: A Preliminary Assessment

Aim The study aims to characterize Fe and Mg co-substituted hydroxyapatite nanoparticles (FeMgHAPn) and assess the antimicrobial properties of FeMgHAPn-incorporated orthodontic composite. Materials and methods FeMgHAPn was synthesized using the sol-gel method, and the prepared nanoparticle powder was characterized using Fourier Transform Infrared Spectroscopy (FTIR), energy-dispersive X-ray analysis (EDX)) and scanning electron microscopic (SEM) analysis. The FeMgHAPn was incorporated into a commercially available orthodontic composite in two concentrations (40 and 20 μL), and the structure was examined using SEM. The FeMgHAPn-incorporated composite was tested for its antimicrobial efficacy against Streptococcus mutans, Staphylococcus aureus, and Escherichia coli using the agar-well diffusion method. The zones of inhibition (ZOI) were measured in millimeters (mm). Results The characterization of the FeMgHAPn indicated the successful formation of the nanoparticle without any impurities or byproducts. The high concentration (40 μL) of FeMgHAPn-incorporated orthodontic composite showed the maximum ZOI against all three microbes, followed by the low concentration (20 μL) and the control group. Conclusion The FeMgHAPn-incorporated orthodontic composite showed promising antimicrobial activity against caries-causing S. mutans, S. aureus, and E. coli.

Metal Oxide Nanoparticles in Food Packaging and Their Influence on Human Health

It is a matter of common knowledge in the literature that engineered metal oxide nanoparticles have properties that are efficient for the design of innovative food/beverage packages. Although nanopackages have many benefits, there are circumstances when these materials are able to release nanoparticles into the food/beverage matrix. Once dispersed into food, engineered metal oxide nanoparticles travel through the gastrointestinal tract and subsequently enter human cells, where they display various behaviors influencing human health or wellbeing. This review article provides an insight into the antimicrobial mechanisms of metal oxide nanoparticles as essential for their benefits in food/beverage packaging and provides a discussion on the oral route of these nanoparticles from nanopackages to the human body. This contribution also highlights the potential toxicity of metal oxide nanoparticles for human health. The fact that only a small number of studies address the issue of food packaging based on engineered metal oxide nanoparticles should be particularly noted.

Antibacterial and physical properties of resin cements containing MgO nanoparticles

Cariogenic bacteria and dental plaque biofilm at prosthesis margins are considered a primary risk factor for failed restorations. Resin cement containing antibacterial agents can be beneficial in controlling bacteria and biofilm. This work aimed to evaluate the impact of incorporating magnesium oxide nanoparticles (MgONPs) as an antibacterial filler into dual-cure resin cement on bacteriostatic activity and physical properties, including mechanical, bonding, and physicochemical properties, as well as performance when subjected to a 5000-times thermocycling regimen. Experimental resin cements containing MgONPs of different mass fractions (0, 2.5%, 5%, 7.5% and 10%) were developed. Results suggested that the inclusion of MgONPs markedly improved the materials' bacteriostatic effect against Streptococcus mutans without compromising the physical properties when its addition reached 7.5 wt%. The mechanical properties of the specimens did not significantly decline after undergoing aging treatment, except for the flexural properties. In addition, the cements displayed good bonding performance and the material itself was not prone to cohesive fracture in the failure mode analysis. Furthermore, MgONPs possibly have played a role in decelerating material aging during thermocycling and enhancing bonding fastness in the early stage of cementation, which requires further investigation. Overall, developing MgONPs-doped resin cements can be a promising strategy to improve the material's performance in inhibiting cariogenic bacteria at restoration margins, in order to achieve a reduction in biofilm-associated secondary caries and a prolonged restoration lifespan.

A Novel Coating of Orthodontic Archwires with Chlorhexidine Hexametaphosphate Nanoparticles

Materials and Methods

A solution of CHX-HMP nanoparticles with an overall concentration of 5 mM for both CHX and HMP was prepared, characterized (using atomic force microscope and Fourier transformation infrared spectroscopy), and used to coat orthodontic stainless steel (SSW) and NiTi archwires (NiTiW). The coated segments were characterized (using scanning electron microscopy SEM with energy dispersive X-ray spectrometry and field emission SEM) and subjected to the elusion assessment.

Results

After having their composition validated, the average size of the CHX-HMP NPs was assessed to be 51.21 nm, and the analysis revealed that the particles had both chlorine and phosphorus. After 30 minutes in the coating solution, NPs deposited on the surface of the SSW and NiTiW. A continuous release of soluble CHX in artificial saliva was detected from both SSW and NiTiW as long as the experiment lasted for 28 days without reaching a plateau. However, the release from coated NiTiW was significantly more than coated SSW at 7, 14, and 28 days. While at day 21, the release from coated SSW was slightly greater than that from the coated NiTiW.

Conclusion

Orthodontic stainless steel and NiTi archwires can be successfully coated with CHX-HMP NPs and give sustained release of CHX along the examined period.

A Polytetrafluoroethylene (PTFE) and Nano-Al2O3 Based Composite Coating with a Bacteriostatic Effect against E. coli and Low Cytotoxicity

The problem of bacterial contamination through surfaces is important for the food industry. In this regard, there is a growing interest in new coatings based on nanoparticles that can provide a long-term antibacterial effect. Aluminum oxide nanoparticles are a good candidate for such coatings due to their availability and good biocompatibility. In this study, a coating containing aluminum oxide nanoparticles was produced using polytetrafluoroethylene as a polymer matrix-a polymer that exhibits excellent mechanical and physicochemical properties and it is not toxic. The obtained coatings based on "liquid Teflon" containing various concentrations of nanoparticles (0.001-0.1 wt%) prevented the bacterial growth, and they did not exhibit a cytotoxicity on animal cells in vitro. Such coatings are designed not only to provide an antibacterial surface effect, but also to eliminate micro damages on surfaces that inevitably occur in the process of food production.