Applications of Nanomaterials in Dental Science: A Review

The potential use of nanozymes as an antibacterial agents in oral infection, periodontitis, and peri-implantitis

Several studies suggest that oral pathogenic biofilms cause persistent oral infections. Among these is periodontitis, a prevalent condition brought on by plaque biofilm. It can even result in tooth loss. Furthermore, the accumulation of germs around a dental implant may lead to peri-implantitis, which damages the surrounding bone and gum tissue. Furthermore, bacterial biofilm contamination on the implant causes soft tissue irritation and adjacent bone resorption, severely compromising dental health. On decontaminated implant surfaces, however, re-osseointegration cannot be induced by standard biofilm removal techniques such as mechanical cleaning and antiseptic treatment. A family of nanoparticles known as nanozymes (NZs) comprise highly catalytically active multivalent metal components. The most often employed NZs with antibacterial activity are those that have peroxidase (POD) activity, among other types of NZs. Since NZs are less expensive, more easily produced, and more stable than natural enzymes, they hold great promise for use in various applications, including treating microbial infections. NZs have significantly contributed to studying implant success rates and periodontal health maintenance in periodontics and implantology. An extensive analysis of the research on various NZs and their applications in managing oral health conditions, including dental caries, dental pulp disorders, oral ulcers, peri-implantitis, and bacterial infections of the mouth. To combat bacteria, this review concentrates on NZs that imitate the activity of enzymes in implantology and periodontology. With a view to the future, there are several ways that NZs might be used to treat dental disorders antibacterially.

Potent biological activity of newly fabricated silver nanoparticles coated by a carbon shell synthesized by electrical arc

Highly effective AgNPs@C was efficiently synthesized by electrical arc powered by single spark unit which was sufficient to ionize the dielectric media (deionized water) through applying strong electric field between the electrodes (silver and carbon). The AgNPs@C shell was characterized in terms of stability, morphology and phase structure. All characterizations showed that the prepared silver nanoparticles were spherical with average size reached 17 nm coated with carbon shell. The antibacterial effect of the synthesized nanoparticles was tested against Pseudomonas aeruginosa in comparison to Ceftazidime (commonly used antibiotic against P. aeruginosa infections). It was revealed that AgNPs@C shell has superior activity with inhibition zone diameter reached 15 mm and minimum inhibitory concentration reached 2 µg/mL. The observed activity was further confirmed by confocal microscope which showed an increased red region, representing the dead cells, correlated with the presence of AgNPs@C. Moreover, transmission electron microscope studies implied the possible AgNPs@C antibacterial mechanism of action was the nanoparticles adherence to the bacterial membrane causing cell lysis. The molecular studies against fimH (virulence adhesion gene), rmpA (mucoid factor encoding gene), and mrkA (biofilm forming gene) proved the inhibition of their genetic expression. The cytotoxic effect of the synthesized AgNPs@C showed CC50 reached 235.5 μg/mL against normal lung cells (L929 cell line).

Implications of graphene-based materials in dentistry: present and future

Since the advent of nanoscience, nanobiomaterials have been applied in the dental industry. Graphene and its derivatives have attracted the most interest of all of them due to their exceptional look, biocompatibility, multiplication differential, and antibacterial capabilities. We outlined the most recent developments about their applications to dentistry in our review. There is discussion of the synthesis processes, architectures, and characteristics of materials based on graphene. The implications of graphene and its counterparts are then meticulously gathered and described. Finally, in an effort to inspire more excellent research, this paper explores the obstacles and potential of graphene-based nanomaterials for dental aspects.

Bioactivation of an orthodontic wire using multifunctional nanomaterials to prevent plaque accumulation

Controlling the growth of biofilm on orthodontic material has become a difficult challenge in modern dentistry. The antibacterial efficacy of currently used orthodontic material becomes limited due to the higher affinity of oral microbial flora for plaque formation on the material surface. Thus it is crutial to device an efficient strategy to prevent plaque buildup caused by pathogenic microbiota. In this work, we have fabricated a bioactive orthodontic wire using titanium nanoparticles (TiO₂NPs) and silver nanoparticles (AgNPs). AgNPs were synthesized from the extracts of Ocimum sanctum, Ocimum tenuiflorum, Solanum surattense, and Syzygium aromaticum, while the TiO₂NPs were synthesized by the Sol-Gel method. The nanoparticles were characterized by various biophysical techniques. The surface of the dental wire was molded by functionalizing these AgNPs followed by an additional coating of TiO₂NPs. Functionalized dental wires were found to counteract the formation of tenacious intraoral biofilm, and showed an enhanced anti-bacterial effect against Multi-Drug Resistant (MDR) bacteria isolated from patients with various dental ailments. Data revealed that such surface coating counteracts the bacterial pathogens by inducing the leakage of Ag ions which eventually disrupts the cell membrane as confirmed from TEM micrographs. The results offer a significant opportunity for innovations in developing nanoparticle-based formulations to modify or fabricate an effective orthodontic material.

Evaluation of Dentin Remineralization with Zinc Oxide and Calcium Fluoride Nanoparticles - An In vitro Study

Background

Partially demineralized dentin is remineralizable when mineral ions are made available in the near vicinity. Nanoparticles (NPs) have wide applications in remineralization process. Zinc promotes remineralization and has a synergistic effect when combined with fluoride. Hence, zinc oxide and calcium fluoride NPs were considered for dentin remineralization.

Aim

The aim of this study was to evaluate the remineralizing ability of zinc oxide and calcium fluoride NPs on demineralized dentin individually and in combined form.

Settings and Design

This was an in vitro study.

Materials and Methods

Forty-eight dentin disks were prepared from the crowns of 12 extracted human molars and were allocated into four groups of 12 each, i.e., Group I - nano zinc oxide (nZnO), Group II - nano calcium fluoride (nCaF2), Group III - combined group (nZnO + nCaF2), and Group IV - artificial saliva (AS, control group). The specimens were demineralized with 37% phosphoric acid and placed in the respective remineralizing solutions for 24 h and 1 month. Calcium (Ca) and phosphorous (P) uptake was measured using energy-dispersive X-ray spectrometry, and structural changes were analyzed using scanning electron microscopy (SEM).

Statistical Analysis

One-way analysis of variance, Student's t-test, and post hoc Tukey's test were used for statistical analysis.

Results

At 1-month interval, all the groups showed an increase in Ca/P ratio, with highest being the combined group (4.24), followed by nCaF2 (3.30), nZnO (1.71), and AS (1.31) groups, and these differences were statistically significant (P = 0.000). On SEM analysis of dentinal samples at 1 month, depositions were evident in intertubular regions, wherein the highest deposits were observed in the nZnO group, followed by nZnO + nCaF2 and nCaF2 groups.

Conclusion

Dentin samples subjected to remineralization with aqueous solutions of nZnO and nCaF2 showed an increase in calcium and phosphorous uptake and also dense granular depositions were evident in intertubular regions of dentin.

Bioactive Inorganic Materials for Dental Applications: A Narrative Review

Over time, much attention has been given to the use of bioceramics for biomedical applications; however, the recent trend has been gaining traction to apply these materials for dental restorations. The bioceramics (mainly bioactive) are exceptionally biocompatible and possess excellent bioactive and biological properties due to their similar chemical composition to human hard tissues. However, concern has been noticed related to their mechanical properties. All dental materials based on bioactive materials must be biocompatible, long-lasting, mechanically strong enough to bear the masticatory and functional load, wear-resistant, easily manipulated, and implanted. This review article presents the basic structure, properties, and dental applications of different bioactive materials i.e., amorphous calcium phosphate, hydroxyapatite, tri-calcium phosphate, mono-calcium phosphate, calcium silicate, and bioactive glass. The advantageous properties and limitations of these materials are also discussed. In the end, future directions and proposals are given to improve the physical and mechanical properties of bioactive materials-based dental materials.

Effects of incorporation of nanoparticles into dental acrylic resins on antimicrobial and physico-mechanical properties: A meta-analysis of in vitro studies

Background

A meta-analysis study was conducted to determine whether the incorporation of nanoparticles into the dental acrylic resins influence the physico-mechanical properties and whether there are the appropriate nanoparticles exhibiting excellent antimicrobial activity against cariogenic bacteria along with acceptable physico-mechanical properties.

Methods

We systematically searched the various databases up to December 2021. The review was performed based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and the Consolidated Standards of Reporting Trials (CONSORT) guidelines. A meta-analysis of physico-mechanical properties was performed by a random-effects model at a 95% confidence interval and the antimicrobial effects were analyzed descriptively.

Results

27 studies were included for the final analysis. There was no statistically significant difference in flexural strength (0.553, [95% confidence interval (CI) 0.501-0.604]), microhardness (0.509, [95% CI 0.278-0.736]), surface roughness (0.753, [95% CI 0.315-0.953]), impact strength (0.90, [95% CI 0.188-0.997]), and elastic modulus (0.848, [95% CI 0.514-0.967]), with nanoparticles addition compared with the control group. Forest plots were not generated for the thermal conductivity, tensile strength, and translucency because of the lack of comparison. Although the articles showed high heterogeneity without the high risk of bias, the finding showed the nanoparticles at low concentrations into dental acrylic resins could improve the antimicrobial activities without adverse effects on their physico-mechanical properties.

Conclusion

Adding the low concentration of nanoparticles such as 0.5% Ag, ≤0.25% TiO₂, and ≤0.25% SiO₂ as the most abundant antimicrobial nanoparticles do not influence their physico-mechanical properties and can be effective in the elimination of cariogenic pathogens.

Graphene-Based Nanomaterials for Dental Applications: Principles, Current Advances, and Future Outlook

With the development of nanotechnology, nanomaterials have been used in dental fields over the past years. Among them, graphene and its derivatives have attracted great attentions, owing to their excellent physicochemical property, morphology, biocompatibility, multi-differentiation activity, and antimicrobial activity. In our review, we summarized the recent progress about their applications on the dentistry. The synthesis methods, structures, and properties of graphene-based materials are discussed. Then, the dental applications of graphene-based materials are emphatically collected and described. Finally, the challenges and outlooks of graphene-based nanomaterials on the dental applications are discussed in this paper, aiming at inspiring more excellent studies.

Adhesive Bond Integrity of Experimental Zinc Oxide Nanoparticles Incorporated Dentin Adhesive: An SEM, EDX, μTBS, and Rheometric Analysis

OBJECTIVE

Our study is aimed at preparing an experimental adhesive (EA) and assessing the influence of adding 5-10 wt.% concentrations of zinc oxide (ZnO) nanoparticles on the adhesive's mechanical properties.

METHODS

Field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) spectroscopy were employed to investigate the morphology and elemental distribution of the filler nanoparticles. To examine the adhesive properties, microtensile bond strength (μTBS) testing, an investigation of the rheological properties, degree of conversion (DC), and analysis of the interface between the adhesive and dentin were carried out.

RESULTS

The SEM micrographs of ZnO nanoparticles demonstrated spherical agglomerates. The EDX plotting confirmed the incidence of Zn and oxygen (O) in the ZnO nanoparticles. The highest μTBS was observed for nonthermocycled (NTC) 5 wt.% ZnO group (32.11 ± 3.60 MPa), followed by the NTC-10 wt.% ZnO group (30.04 ± 3.24 MPa). Most of the failures observed were adhesive in nature. A gradual reduction in the viscosity was observed at higher angular frequencies, and the addition of 5 and 10 wt.% ZnO to the composition of the EA lowered its viscosity. The 5 wt.% ZnO group demonstrated suitable dentin interaction by showing the formation of resin tags, while for the 10 wt.% ZnO group, compromised resin tag formation was detected. DC was significantly higher in the 0% ZnO (EA) group.

CONCLUSION

The reinforcement of the EA with 5 and 10 wt.% concentrations of ZnO nanoparticles produced an improvement in the adhesive's μTBS. However, a reduced viscosity was observed for both nanoparticle-reinforced adhesives, and a negotiated dentin interaction was seen for 10 wt.% ZnO adhesive group. Further research exploring the influence of more filler concentrations on diverse adhesive properties is recommended.

In Vitro Studies concerning Selected Properties of a Composite Material Blended with Nanofluoroapatite Crystals

The aim of the paper was to determine the potential for fluorine release from an original composite material blended with nanofluoroapatite (FAp). The level of fluoride ion emission into deionized water and saline was studied over a period of 12 weeks. Values were recorded after 1, 3, 24, 48, 72, and 96 h and then weekly for a period of 12 weeks. There were statistically significant differences in the periods of fluoride ion release from 5%FAp and 2%FAp materials into saline solution as well as into deionized water. The highest fluorine release from 5%FAp + polymer was observed in the 10th and 11th week of incubation (for saline solution) and in the 9th, 10th, and 11th week (for deionized water). The highest fluorine release from 2%FAp + polymer was observed in the 9th, 11th, and 12th week of incubation for both environments. Total fluoride ion release from 5%FAp + polymer and mean fluoride release levels were similar in 5%FAp and 2%FAp in both environments. Both tested materials (5%FAp and 2%FAp) show the ability to release fluoride ions over a long time in the experimental environment.

Visible-Light-Driven Photocatalysis-Enhanced Nanozyme of TiO2 Nanotubes@MoS2 Nanoflowers for Efficient Wound Healing Infected with Multidrug-Resistant Bacteria

To enhance the catalytic activity of the nanozymes for efficient wound healing infected with multidrug-resistant bacteria, photo-based motivations have been suggested, but attention is mainly focused on the external stimulus of near-infrared light, while the inexhaustible visible one is promising but lack of study. Herein, an efficient visible light-stimulated peroxidase-like nanozyme system, TiO₂ nanotubes coated with MoS₂ nanoflowers (TiO₂ NTs@MoS₂ ), is discovered for efficient bacterial treatment. Based on the synergetic effects between the two components, the bandgap of the TiO₂ NTs can be narrowed from 3.2 to 2.97 eV due to the MoS₂ loading, which extended the light response of TiO₂ to visible-light range and enhanced the photocatalytic activity accordingly. Meanwhile, the peroxidase-like activity of MoS₂ can be significantly enhanced due to the combination with TiO₂ NTs in return. Especially, the peroxidase-like activity of the TiO₂ NTs@MoS₂ nanocomposite can be further improved under the sunlight irradiation, rendering much more hydroxyl radical (•OH) generation. Accordingly, the as-obtained TiO₂ NTs@MoS₂ shows an outstanding antibacterial effect against drug-resistance extended spectrum β-lactamases producing Escherichia coli and methicillin-resistant Staphylococcus aureus under the visible light. In vivo wound healing test further confirms the high antimicrobial efficiency and good biocompatibility of the synergistic antimicrobial system.

Neurodevelopmental toxicity of alumina nanoparticles to zebrafish larvae: Toxic effects of particle sizes and ions

The aim of this study was to explore the mechanism of neurodevelopmental toxicity of alumina nanoparticles (AlNPs) on zebrafish larvae, specifically, the toxic effects of AlNPs of different particle sizes and of dissolved aluminum ions. AlNPs with sizes of 13 nm (13 nm-Al) and 50 nm (50 nm-Al) were used as the main research objects; while nanocarbon particles with sizes of 13 nm (13 nm-C) and 50 nm (50 nm-C) as particle-size controls; and an aluminum chloride solution (Al³⁺) as an ion control. Zebrafish embryos were exposed to different treatments from 6 h post-fertilization (hpf) to 168 hpf. Deformities were observed at different time points. Neurodevelopmental behavior tests were carried out, and oxidative stress responses and transcriptional alterations in autophagy-related genes were assessed. Malformations occurred in the 13 nm-Al, 50 nm-Al, and Al³⁺ treated groups at different developmental stages of zebrafish larval, but no malformations were observed in the 13 nm-C or 50 nm-C groups. In addition, the average speed, distance travelled and thigmotaxis in zebrafish larvae decreased in the AlNPs treated group, and the effects were related to the particle sizes. Furthermore, increases in the oxidative stress response and autophagy-related genes expression were also related to the particle sizes of AlNPs as well. In conclusion, the mechanism underlying the neurodevelopmental toxicity of AlNPs on zebrafish larvae mainly depended on the size of the nanoparticles, and dissolved Al³⁺ also contributes to the toxic effects.

Dental Applications of Systems Based on Hydroxyapatite Nanoparticles—An Evidence-Based Update

Hydroxyapatite is one of the most studied biomaterials in the medical and dental field, because of its biocompatibility; it is the main constituent of the mineral part of teeth and bones. In dental science, hydroxyapatite nanoparticles (HAnps) or nano-hydroxyapatite (nano-HA) have been studied, over the last decade, in terms of oral implantology and bone reconstruction, as well in restorative and preventive dentistry. Hydroxyapatite nanoparticles have significant remineralizing effects on initial enamel lesions, and they have also been used as an additive material in order to improve existing and widely used dental materials, mainly in preventive fields, but also in restorative and regenerative fields. This paper investigates the role of HAnps in dentistry, including recent advances in the field of its use, as well as their advantages of using it as a component in other dental materials, whether experimental or commercially available. Based on the literature, HAnps have outstanding physical, chemical, mechanical and biological properties that make them suitable for multiple interventions, in different domains of dental science. Further well-designed randomized controlled trials should be conducted in order to confirm all the achievements revealed by the in vitro or in vivo studies published until now.

An overview of recent progress in dental applications of zinc oxide nanoparticles

Nanotechnology is an emerging field of science, engineering, and technology concerning the materials in nanoscale dimensions. Several materials are used in dentistry, which can be modified by applying nanotechnology. Nanotechnology has various applications in dentistry to achieve reliable treatment outcomes. The most common nanometals used in dental materials are gold, silver, copper oxide, magnesium oxide, iron oxide, cerium oxide, aluminum oxide, titanium dioxide, and zinc oxide (ZnO). ZnO nanoparticles (NPs), with their unparalleled properties such as high selectivity, enhanced cytotoxicity, biocompatibility, and easy synthesis as important materials were utilized in the field of dentistry. With this background, the present review aimed to discuss the current progress and gain an insight into applications of ZnO NPs in nanodentistry, including restorative, endodontic, implantology, periodontal, prosthodontics, and orthodontics fields.

Nanomaterials Application in Orthodontics

Nanotechnology has gained importance in recent years due to its ability to enhance material properties, including antimicrobial characteristics. Nanotechnology is applicable in various aspects of orthodontics. This scientific work focuses on the concept of nanotechnology and its applications in the field of orthodontics, including, among others, enhancement of antimicrobial characteristics of orthodontic resins, leading to reduction of enamel demineralization or control of friction force during orthodontic movement. The latter one enables effective orthodontic treatment while using less force. Emphasis is put on antimicrobial and mechanical characteristics of nanomaterials during orthodontic treatment. The manuscript sums up the current knowledge about nanomaterials' influence on orthodontic appliances.

Application of Nanotechnology in Orthodontic Materials: A State-of-the-Art Review

Nanotechnology refers to the science that manipulates matter at molecular and atomic levels, and studies matter at the nanoscale level to detect and exploit the useful properties that derive from these dimensions; materials with components less than 100 nm in at least one dimension are called nanomaterials. Nanotechnology is applied in many fields, such as medicine (nanomedicine) and dentistry (nano-dentistry). The purpose of these innovations and research in this field is to improve human life and health. This article aims to summarize and describe what the most recent and known innovations of nanotechnology in dentistry are, focusing on and paying particular attention to the branch that is orthodontics, and on the application of new nanomaterials in the realization, for example, of orthodontic elastomeric ligatures, orthodontic power chains, and orthodontic miniscrews. We also address a very important topic in orthodontics, which is how to reduce the friction force.

In vitro bioactivity of AH plus with the addition of nano-magnesium hydroxide

Background

AH Plus (AH) has been widely used as a root canal sealer in the endodontic field due to its superior physicochemical properties. However, clinical application of AH is limited due to its weak bioactivity.

Methods

In this study, we have developed an AH cement containing nano-magnesium hydroxide (NMH) as an additive to enhance the bioactivity of AH. The NMH can neutralize pH and facilitate bone formation. The objective of this study was to evaluate the effects of NMH and modified AH on osteoblasts behavior in vitro. The CCK-8, alkaline phosphatase (ALP) staining, and real-time polymerase chain reaction (PCR) assays were used to assess the proliferation and differentiation of MC3T3-E1 cells, respectively. The adhesion and spreading of MC3T3-E1 cells were investigated in vitro by scanning electron microscopy (SEM). Meanwhile, the flow and magnesium ion release of the modified AH was also concerned.

Results

In vitro cell assays further showed that the addition of NMH into AH cement, which was denoted as modified AH (especially AH+3%NMH), could effectively improve the proliferation and osteogenic differentiation of MC3T3-E1 cells.

Conclusions

Taken all together, we believe that the modified AH samples (especially AH+3%NMH) have outstanding biocompatibility and osteogenic properties and may have great potential in endodontic field.

Bioactive Glasses and Glass-Ceramics for Healthcare Applications in Bone Regeneration and Tissue Engineering

The discovery of bioactive glasses (BGs) in the late 1960s by Larry Hench et al. was driven by the need for implant materials with an ability to bond to living tissues, which were intended to replace inert metal and plastic implants that were not well tolerated by the body. Among a number of tested compositions, the one that later became designated by the well-known trademark of 45S5 Bioglass® excelled in its ability to bond to bone and soft tissues. Bonding to living tissues was mediated through the formation of an interfacial bone-like hydroxyapatite layer when the bioglass was put in contact with biological fluids in vivo. This feature represented a remarkable milestone, and has inspired many other investigations aiming at further exploring the in vitro and in vivo performances of this and other related BG compositions. This paradigmatic example of a target-oriented research is certainly one of the most valuable contributions that one can learn from Larry Hench. Such a goal-oriented approach needs to be continuously stimulated, aiming at finding out better performing materials to overcome the limitations of the existing ones, including the 45S5 Bioglass®. Its well-known that its main limitations include: (i) the high pH environment that is created by its high sodium content could turn it cytotoxic; (ii) and the poor sintering ability makes the fabrication of porous three-dimensional (3D) scaffolds difficult. All of these relevant features strongly depend on a number of interrelated factors that need to be well compromised. The selected chemical composition strongly determines the glass structure, the biocompatibility, the degradation rate, and the ease of processing (scaffolds fabrication and sintering). This manuscript presents a first general appraisal of the scientific output in the interrelated areas of bioactive glasses and glass-ceramics, scaffolds, implant coatings, and tissue engineering. Then, it gives an overview of the critical issues that need to be considered when developing bioactive glasses for healthcare applications. The aim is to provide knowledge-based tools towards guiding young researchers in the design of new bioactive glass compositions, taking into account the desired functional properties.

Bio-inspired engineering of cell- and virus-like nanoparticles for drug delivery

The engineering of future generations of nanodelivery systems aims at the creation of multifunctional vectors endowed with improved circulation, enhanced targeting and responsiveness to the biological environment. Moving past purely bio-inert systems, researchers have begun to create nanoparticles capable of proactively interacting with the biology of the body. Nature offers a wide-range of sources of inspiration for the synthesis of more effective drug delivery platforms. Because the nano-bio-interface is the key driver of nanoparticle behavior and function, the modification of nanoparticles' surfaces allows the transfer of biological properties to synthetic carriers by imparting them with a biological identity. Modulation of these surface characteristics governs nanoparticle interactions with the biological barriers they encounter. Building off these observations, we provide here an overview of virus- and cell-derived biomimetic delivery systems that combine the intrinsic hallmarks of biological membranes with the delivery capabilities of synthetic carriers. We describe the features and properties of biomimetic delivery systems, recapitulating the distinctive traits and functions of viruses, exosomes, platelets, red and white blood cells. By mimicking these biological entities, we will learn how to more efficiently interact with the human body and refine our ability to negotiate with the biological barriers that impair the therapeutic efficacy of nanoparticles.