Enhancing the Physical, Antimicrobial, and Osteo/Odontogenic Properties of a Sol-Gel-Derived Tricalcium Silicate by Graphene Oxide for Vital Pulp Therapies

OBJECTIVES

This study developed a sol-gel tricalcium silicate/graphene oxide (TCS-GO) composite and examined its physicochemical properties, antimicrobial activity, and osteo/odontogenic effect on dental pulp stem cells.

METHODS

Tricalcium silicate was synthesized and combined with graphene oxide at three different concentrations, namely 0.02%, 0.04%, and 0.08% w/w, while tricalcium silicate and mineral trioxide aggregate served as controls. The setting time, compressive strength, pH, and calcium ion release of the composites were evaluated, as well as antimicrobial properties against Streptococcus mutans and Lactobacillus acidophilus. Additionally, the viability of dental pulp stem cells; apatite forming ability; and the gene expression of Alkaline phosphatase, Dentin sialophosphoprotein, and Runt-related transcription factor 2 were assessed.

RESULTS

TCS-GO (0.08%) showed a significantly shorter setting time and higher compressive strength when compared to MTA (p < 0.05). Additionally, tricalcium silicate and TCS-GO groups showed a higher release of Ca ions than MTA, with no significant difference in pH values among the different groups. TCS-GO (0.08%) also demonstrated a significantly stronger antimicrobial effect against Lactobacillus acidophilus compared to MTA (p < 0.05). ALP expression was higher in TCS-GO (0.08%) than MTA on days 3 and 7, while DSPP expression was higher in TCS-GO (0.08%) than MTA on day 3 but reversed on day 7. There was no significant difference in RUNX2 expression between TCS-GO (0.08%) and MTA on days 3 and 7.

CONCLUSIONS

The TCS-GO (0.08%) composite demonstrated superior physicochemical characteristics and antimicrobial properties compared to MTA. Moreover, the early upregulation of ALP and DSPP markers in TCS-GO (0.08%) indicates that it has the potential to promote and enhance the osteo/odontogenic differentiation of DPSCs.

Color change of tooth-colored restorative materials bonded to silver diamine fluoride-treated dentine: a systematic review

BACKGROUND

The desirable properties of silver diamine fluoride (SDF) make it an effective agent for managing dental caries and tooth hypersensitivity. There are several clinical instances that SDF application might precede the placement of direct tooth-colored restorations. On the other hand, SDF stains demineralized/carious dental tissues black, which might affect the esthetic outcomes of such restorations. Color is a key parameter of esthetics in dentistry. Therefore, this study aims to systematically review dental literature on color/color change of tooth-colored restorations placed following the application of SDF on dentine.

METHODS

Comprehensive search of PubMed, Embase, Scopus and ISI Web of Science databases (until August 2023) as well as reference lists of retrieved studies was performed. In vitro studies reported color or color change of tooth-colored restorative materials applied on SDF-treated dentine were included. Methodological quality assessment was performed using RoBDEMAT tool. Pooled weighted mean difference (WMD) and 95% confidence interval (95% CI) was calculated.

RESULTS

Eleven studies/reports with a total of 394 tooth-colored restorations placed following a) no SDF (control) or b) SDF with/without potassium iodide (KI)/glutathione dentine pre-treatments were included. Color change was quantified using ∆E formulas in most reports. The pooled findings for the comparison of resin-based composite (RBC) restorations with and without prior 38% SDF + KI application revealed no statistically significant differences in ∆E values at short- and long-term evaluations (~ 14 days: WMD: -0.56, 95% CI: -2.09 to 0.96; I2: 89.6%, and ~ 60 days: WMD: 0.11; 95% CI: -1.51 to 1.72; I2: 76.9%). No studies provided sufficient information for all the items in the risk of bias tool (moderate to low quality).

CONCLUSIONS

The limited evidence suggested comparable color changes of RBC restorations with and without 38% SDF + KI pre-treatment up to 60 days. The included studies lacked uniformity in methodology and reported outcomes. Further studies are imperative to draw more definite conclusions.

PROTOCOL REGISTRATION

The protocol of this systematic review was registered in PROSPERO database under number CRD42023485083.

Advanced Dentistry Biomaterials Containing Graphene Oxide

The aim of this study was to obtain three experimental resin-based cements containing GO and HA-Ag for posterior restorations. The samples (S0, S1, and S2) shared the same polymer matrix (BisGMA, TEGDMA) and powder mixture (bioglass (La2O3 and Sr-Zr), quartz, GO, and HA-Ag), with different percentages of graphene oxide (0%, 0.1%, 0.2% GO) and silver-doped hydroxyapatite (10%, 9.9%, 9.8% HA-Ag). The physical-chemical properties (water absorption, degree of conversion), mechanical properties (DTS, CS, FS), structural properties (SEM, AFM), and antibacterial properties (Staphylococcus aureus, Enterococcus faecalis, Streptococcus mutans, Porphyromonas gingivalis, and Escherichia coli) were investigated. The results showed that the mechanical properties, except for the diametral tensile test, increased with the rise in the %GO. After 28 days, water absorption increased with the rise in the %GO. The surface structure of the samples did not show major changes after water absorption for 28 days. The antibacterial effects varied depending on the samples and bacterial strains tested. After increasing the %GO and decreasing the %HA-Ag, we observed a more pronounced antibacterial effect. The presence of GO, even in very small percentages, improved the properties of the tested experimental cements.

Microhardness, Surface Roughness, and Wear Resistance Enhancement of Reinforced Conventional Glass Ionomer Cement Using Fluorinated Graphene Oxide Nanosheets

OBJECTIVES

 Conventional glass ionomer cements (GICs) have been considered the most prevalent restorative material however; the reduced mechanical qualities and decreased wear resistance have been the main challenges facing their wide clinical application. This study was designed to assess the mechanical properties of fluorinated graphene (FG) oxide-modified conventional GIC.

MATERIALS AND METHODS

 Composites of FG/GIC samples were prepared using (Medifil from PROMEDICA, Germany, shade A3) at different concentrations (0wt%) control group and (1wt%, 2wt% and 3wt% FG) groups using cylindrical molds (3mm × 6mm). FG was prepared using hydrothermal technique and characterized using XPERT-PRO Powder Diffractometer system for X-ray diffraction analysis and JEOL JEM-2100 high resolution transmission electron microscope. Vickers' hardness and wear resistance of GI samples were measured. Mechanical abrasion was performed via three-body tooth brushing wear test using ROBOTA chewing simulator coupled with a thermocycling protocol (Model ACH-09075DC-T, AD-Tech Technology Co., Ltd., Leinfelden-Echterdingen, Germany).

STATISTICAL ANALYSIS

 Comparisons between groups with respect to normally distributed numeric variables were performed using one-way analysis of variance test followed by posthoc test. While paired t-test was utilized for comparing data within the same group.

RESULTS

The surface roughness values of GICs (1wt% FG) and (2wt% FG) composites were significantly lower than those of the control and 3wt%FG groups. Vickers' hardness numbers were significantly higher in FG/GICs composites than in the control group (p≤0.05).

CONCLUSION

 GIC/FG combinations have sufficient strength to resist the occlusion stresses with improved hardness as compared with conventional GIC. GIC/FG appeared to be a promising restorative material.

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.

Can Graphene Pave the Way to Successful Periodontal and Dental Prosthetic Treatments? A Narrative Review

Graphene, as a promising material, holds the potential to significantly enhance the field of dental practices. Incorporating graphene into dental materials imparts enhanced strength and durability, while graphene-based nanocomposites offer the prospect of innovative solutions such as antimicrobial dental implants or scaffolds. Ongoing research into graphene-based dental adhesives and composites also suggests their capacity to improve the quality and reliability of dental restorations. This narrative review aims to provide an up-to-date overview of the application of graphene derivatives in the dental domain, with a particular focus on their application in prosthodontics and periodontics. It is important to acknowledge that further research and development are imperative to fully explore the potential of graphene and ensure its safe use in dental practices.

Bioactive Materials for Caries Management: A Literature Review

Researchers have developed novel bioactive materials for caries management. Many clinicians also favour these materials, which fit their contemporary practice philosophy of using the medical model of caries management and minimally invasive dentistry. Although there is no consensus on the definition of bioactive materials, bioactive materials in cariology are generally considered to be those that can form hydroxyapatite crystals on the tooth surface. Common bioactive materials include fluoride-based materials, calcium- and phosphate-based materials, graphene-based materials, metal and metal-oxide nanomaterials and peptide-based materials. Silver diamine fluoride (SDF) is a fluoride-based material containing silver; silver is antibacterial and fluoride promotes remineralisation. Casein phosphopeptide-amorphous calcium phosphate is a calcium- and phosphate-based material that can be added to toothpaste and chewing gum for caries prevention. Researchers use graphene-based materials and metal or metal-oxide nanomaterials as anticaries agents. Graphene-based materials, such as graphene oxide-silver, have antibacterial and mineralising properties. Metal and metal-oxide nanomaterials, such as silver and copper oxide, are antimicrobial. Incorporating mineralising materials could introduce remineralising properties to metallic nanoparticles. Researchers have also developed antimicrobial peptides with mineralising properties for caries prevention. The purpose of this literature review is to provide an overview of current bioactive materials for caries management.

Non-enzymatic detection of glucose levels in human blood plasma by a graphene oxide-modified organic transistor sensor

We herein report an organic transistor functionalized with a phenylboronic acid derivative and graphene oxide for the quantification of plasma glucose levels, which has been achieved by the minimization of interferent effects derived from physical protein adsorption on the detection electrode.

Graphene-Based Materials in Dental Applications: Antibacterial, Biocompatible, and Bone Regenerative Properties

Graphene-based materials have been shown to have advantageous properties in biomedical and dental applications due to their high mechanical, physiochemical, antibacterial, and stem cell differentiating properties. Although graphene-based materials have displayed appropriate biocompatible properties when used in implant materials for orthopedic applications, little research has been performed to specifically test the biocompatibility of graphene for dental applications. The oral environment, compared to the body, varies greatly and must be considered when evaluating biocompatibility requirements for dental applications. This review will discuss in vitro and in vivo studies that assess graphene's cytotoxicity, antibacterial properties, and cell differentiation ability to evaluate the overall biocompatibility of graphene-based materials for dental applications. Particle shape, size, and concentration were found to be major factors that affected overall biocompatibility of graphene.

Graphene on dentistry: A bibliometric and scientometric analysis

Background

Today, the development of dental materials is a very important issue. Graphene has been used in dentistry to strengthen many materials.

Aim

The aim of this study was to analyze leading countries and to identify the preferred journals, the most commonly used keywords, and the most productive authors in the field of graphene.

Materials and Methods

The search keyword was "graphene" on the Web of Science database; the search was restricted to before 2022. The selected search from the Web of Science database included the title of articles, authors, year of publication, country, citation count, and keywords. An analysis was performed regarding citations and documents, authors, journals, and keywords using a bibliometric software program. All articles were evaluated and subjected to scientometric analysis.

Results

Twenty six articles were included in the study. There has been a remarkable increase in published articles from past to present, and a regular increase is observed in the number of citations. Dental Materials has highest number of publications among the articles included in the present study. Dr. Rosa, who had the highest number of citations, is also the most effective author. Graphene has many studies in dentistry with different materials. As per the data obtained, graphene, graphene oxide, and peri-implantitis are the most used keywords and Singapore and China are at the forefront of the countries where the articles are published.

Conclusion

This bibliometric analysis reveals the progress and trend of research on graphene in dentistry and extensive collaborations between authors, countries, and institutions. The findings of this study can help inspire researchers to plan new studies and collaborate on graphene.

Caries Management with Non-Metallic Nanomaterials: A Systematic Review

BACKGROUND

Non-metallic nanomaterials do not stain enamel or dentin. Most have better biocompatibility than metallic nanomaterials do for management of dental caries.

OBJECTIVE

The objective of this study is to review the types, properties and potential uses of non-metallic nanomaterials systematically for managing dental caries.

METHODS

Two researchers independently performed a literature search of publications in English using PubMed, Scopus and Web of Science. The keywords used were (nanoparticles OR nanocomposites OR nanomaterials) AND (caries OR tooth decay). They screened the titles and abstracts to identify potentially eligible publications of original research reporting non-metallic nanomaterials for caries management. Then, they retrieved and studied the full text of the identified publications for inclusion in this study.

RESULTS

Out of 2497 resulting publications, this study included 75 of those. The non-metallic nanomaterials used in these publications were categorized as biological organic nanomaterials (n=45), synthetic organic nanomaterials (n=15), carbon-based nanomaterials (n=13) and selenium nanomaterials (n=2). They inhibited bacteria growth and/or promoted remineralization. They could be incorporated in topical agents (29/75, 39%), dental adhesives (11/75, 15%), restorative fillers (4/75, 5%), dental sealant (3/75, 4%), oral drugs (3/75, 4%), toothpastes (2/75, 3%) and functional candies (1/75, 1%). Other publications (22/75, 29%) do not mention specific applications. However, most publications (67/75, 89%) were in vitro studies. Six publications (6/75, 8%) were animal studies, and only two publications (2/75, 3%) were clinical studies.

CONCLUSION

The literature showed non-metallic nanomaterials have antibacterial and/or remineralising properties. The most common type of non-metallic nanomaterials for caries management is organic nanomaterials. Non-metallic nanomaterials can be incorporated into dental sealants, toothpaste, dental adhesives, topical agents and even candies and drugs. However, the majority of the publications are in vitro studies, and only two publications are clinical studies.

In Vitro Studies of Graphene for Management of Dental Caries and Periodontal Disease: A Concise Review

Graphene is a single-layer two-dimensional carbon-based nanomaterial. It presents as a thin and strong material that has attracted many researchers’ attention. This study provides a concise review of the potential application of graphene materials in caries and periodontal disease management. Pristine or functionalized graphene and its derivatives exhibit favorable physicochemical, mechanical, and morphological properties applicable to biomedical applications. They can be activated and functionalized with metal and metal nanoparticles, polymers, and other small molecules to exhibit multi-differentiation activities, antimicrobial activities, and biocompatibility. They were investigated in preventive dentistry and regenerative dentistry. Graphene materials such as graphene oxide inhibit cariogenic microbes such as Streptococcus mutans. They also inhibit periodontal pathogens that are responsible for periodontitis and root canal infection. Graphene-fluorine promotes enamel and dentin mineralization. These materials were also broadly studied in regenerative dental research, such as dental hard and soft tissue regeneration, as well as periodontal tissue and bone regeneration. Graphene oxide-based materials, such as graphene oxide-fibroin, were reported as promising in tissue engineering for their biocompatibility, bioactivity, and ability to enhance cell proliferation properties in periodontal ligament stem cells. Laboratory research showed that graphene can be used exclusively or by incorporating it into existing dental materials. The success of laboratory studies can translate the application of graphene into clinical use.

Enhancing the mechanical properties and providing bioactive potential for graphene oxide/montmorillonite hybrid dental resin composites

This in vitro study synthetized hybrid composite nanoparticles of graphene oxide (GO) and montmorillonite MMt (GO-MMt) by ultrasound treatments. Samples were characterized by X-ray diffraction, FT-Raman, FTIR, TEM and SEM. The effect of their incorporation (0.3% and 0.5%) on the mechanical properties in a resin-based composite (RBC) and their bioactivity potential were evaluated. The specimens were characterized by evaluating their 3-point flexural strength (n = 6), modulus of elasticity (n = 6), degree of conversion (n = 6), microhardness (n = 6), contact angle (n = 3) and SEM analysis (n = 3). In vitro test in SBF were conducted in the RBCs modified by the hybrid. Overall, the synthetized hybrid composite demonstrated that GO was intercalated with MMt, showing a more stable compound. ANOVA and Tukey test showed that RBC + 0.3% GO-MMt demonstrated superior values of flexural strength, followed by RBC + 0.5% GO-MMt (p < 0.05) and both materials showed higher values of microhardness. All groups presented a contact angle below 90°, characterizing hydrophilic materials. RBCs modified by the hybrid showed Ca and P deposition after 14 days in SBF. In conclusion, RBCs composed by the hybrid showed promising results in terms of mechanical properties and bioactive potential, extending the application of GO in dental materials.

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.

Electrophoresis-Aided Biomimetic Mineralization System Using Graphene Oxide for Regeneration of Hydroxyapatite on Dentin

Graphene oxide (GO) is an emerging luminescent carbon nanomaterial with the ability to foster hydroxyapatite (HA). A specially designed electrophoresis system can be used to accelerate the mineralization process. The aim of this study was to promote HA crystal growth on demineralized dentin using a GO incorporated electrophoresis system. GO was successfully synthesized by carbonization of citric acid and its presence was confirmed by Fourier transform infrared and UV-visible spectrophotometry evaluation. Dentin slices were placed in demineralized solution and divided into control (without the electrophoresis system) and experimental group. Demineralized dentin slices in the experimental group were remineralized using the electrophoresis system for 8 h/1.0 mA, with one subgroup treated without GO and the other with GO. Energy dispersive spectroscopy evaluation showed that the calcium/phosphate ratio of the crystal formed in control and experimental group with addition of GO was close to natural hydroxyapatite. However, scanning electron microscopy evaluation showed that the exposed dentinal tubules were occluded with rod-like crystals, which is similar to native enamel morphology, in the experimental group with addition of GO compared to the flake-like crystal in the control group. Mechanical evaluation revealed that the nanohardness and modulus of remineralized dentin were significantly higher in the experimental group. In conclusion, GO is a promising material to remineralize dentin and the introduction of an electrophoresis system can accelerate its process.

Metal and Metal Oxide Nanoparticles in Caries Prevention: A Review

Nanoparticles based on metal and metallic oxide have become a novel trend for dental use as they interfere with bacterial metabolism and prevent biofilm formation. Metal and metal oxide nanoparticles demonstrate significant antimicrobial activity by metal ion release, oxidative stress induction and non-oxidative mechanisms. Silver, zinc, titanium, copper, and magnesium ions have been used to develop metal and metal oxide nanoparticles. In addition, fluoride has been used to functionalise the metal and metal oxide nanoparticles. The fluoride-functionalised nanoparticles show fluoride-releasing properties that enhance apatite formation, promote remineralisation, and inhibit demineralisation of enamel and dentine. The particles' nanoscopic size increases their surface-to-volume ratio and bioavailability. The increased surface area facilitates their mechanical bond with tooth tissue. Therefore, metal and metal oxide nanoparticles have been incorporated in dental materials to strengthen the mechanical properties of the materials and to prevent caries development. Another advantage of metal and metal oxide nanoparticles is their easily scalable production. The aim of this study is to provide an overview of the use of metal and metal oxide nanoparticles in caries prevention. The study reviews their effects on dental materials regarding antibacterial, remineralising, aesthetic, and mechanical properties.

Formulation of nano-graphene doped with nano silver modified dentin bonding agents with enhanced interfacial stability and antibiofilm properties

OBJECTIVE

The aim of this study was to synthesize and characterize reduced nano graphene oxide (RGO) and graphene nanoplatelets (GNPs) doped with silver nanoparticles (nAg) and to prepare an experimental dentin adhesive modified with RGO/nAg and GNP/nAg nanofillers for studying various biological and mechanical properties after bonding to tooth dentin.

METHODS

Nanoparticles were characterized for their morphology and chemical structure using electron microscopy and infrared spectroscopy. Experimental dentin adhesive was modified using two weight percentage (0.25% and 0.5%) of RGO/nAg and GNP/nAg to study its degree of conversion (DC), antimicrobial potential, and cytotoxicity. The effect and significance of these modified bonding agents on resin-dentin bonded interface were investigated by evaluating interfacial nanoleakage, micropermeability, nanodynamic mechanical analysis, micro-tensile bond strength (µTBS), and four-point bending strength (BS), RESULTS: Both 0.25% and 0.5% GNP/nAg graphene-modified adhesives showed comparable DC values to the commercial and experimental adhesive (range: 42-46%). The bacterial viability of the groups 0.25% and 0.5% GNP-Ag remained very low under 25% compared to RGO/nAg groups with low cytotoxicity profiles (cell viability>85%). Resin-bonded dentin interface created with GNP/nAg showed homogenous, well-defined hybrid layer and regularly formed long resin tags devoid of any microporosity as evidenced by SEM and confocal microscopy. The lowest nanoleakage and highest bending strength and µTBS was recorded for 0.25% GNP/nAg after 12 months of ageing. A significantly increased nanoelasticity was seen for all experimental groups except for control groups.

SIGNIFICANCE

The addition of 0.25% GNP/nAg showed optimized anti-biofilm properties without affecting the standard adhesion characteristics.

Nanoparticle incorporated dentin bonding agent to caries effected dentin treated by photodynamic therapy, laser or chlorhexidine

PURPOSE

This study aims to evaluate the microtensile bond strength (µTBS) and failure modes of graphene nanoplatelets doped with hydroxyapatite (GNP-HA) modified self-etch dentin bonding agent (DBA) to caries effected dentin (CAD) after various conventional and laser disinfection protocols.

MATERIALS AND METHODS

Graphene nanoplatelets and HA nanoparticles were doped and incorporated in DBA. Fifty carious human molar teeth were used for the experiment. CAD specimens were divided into five groups (n=10/group) into CAD undergoing no disinfection treatment (Group-CAD), 2% chlorhexidine disinfection (Group-CHX), 6% NaOCl disinfection (Group-NaOCl), methylene blue assisted PDT (Group-MB-PDT), and Er,Cr:YSGG laser application (Group-Er,Cr:YSGG). Following the respective disinfection techniques, the GNP-HA modified adhesive was applied to all treated CAD surface. Subsequently µTBS and failure modes were analyzed.

RESULTS

Representative scanning electron microscope images (SEM images) of the synthesized GNP-HA indicated flakes of graphene with varying size lengthwise (>500 nm) with 1-2 nm width. The doped HA showed round and spherical morphology conjugated over the surface of the GNP measuring 40 -100 nm in diameter. CAD group that underwent no treatment represented the highest µTBS (29.43 MPa). Within the tested specimens, MB-PDT (22.37 MPa) and Er,Cr:YSGG (21.85 MPa) showed the highest µTBS values than CHX (15.69 MPa) and NaOCl (11.46 MPa). However, there was no significant difference between MB-PDT and Er,Cr:YSGG (p>0.05) and a significant difference existed between CHX and NaOCl (p<0.05). Equal distribution of cohesive and adhesive failures was noted for CAD, CHX and NaOCl treated specimens. A majority of adhesive failures existed in the MB-PDT groups. While admixed and adhesive failures were higher in Er,Cr:YSGG treated samples.

CONCLUSIONS

The outcome of this study suggests that CAD restored by GNP-HA modified self-etch adhesive showed highest bond strength after MB-PDT and Er,Cr:YSGG protocols with low amount of adhesive failure.

[Raman spectroscopy and its application in different areas of medicine]

The aim of the review is to learn about the areas of application of the Raman spectroscopy in medicine, particularly in dentistry. The method is widely used in biology, medicine, pharmacy, forensic science, gemology, food industry and other industries. The main advantages of Raman spectroscopy are no need for sample preparation and small amounts of the object of study, as well as the ability to contactlessly obtain unique information about the conformation and microenvironment of living cell molecules. The disadvantages are high costs of the equipment that are compensated with the long-term use by having no costs for additional reagents. The combinatorial scattering is used in dermatology, as it is a high-accuracy automated method of visualization and diagnostics of both benign growths as pigmented nevus, seborrheic keratosis, and malignant neoplasms as melanoma and basal cell carcinoma. This method is an analytical tool for diagnosing various diseases, making the direct measurements in hard and liquid media easier, does not require special treatment of samples and is not sensitive to absorption bands. The Raman spectroscopy use in dentistry allows diagnosing and comparative analysis of the changes of hard tissues of teeth and mucous membrane of the mouth, which improves security and rationalization of treatment and further prevention of complications before and after making different operations.

Synergistic effect of graphene oxide/calcium phosphate nanofiller in a dentin adhesive on its dentin bond integrity and degree of conversion. A scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared, micro-Raman, and bond strength study

The objective was to formulate and analyze a dentin adhesive incorporated with graphene oxide (GO) nanoparticle and calcium phosphate (CaP) composite. Methods comprising of scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy (EDX), micro-Raman spectroscopy, shear bond strength (SBS), and Fourier transform infrared (FTIR) spectroscopy were used to characterize nanoparticle composite, dentin bond toughness, degree of conversion (DC), and adhesive-dentin interaction. Postsynthesis of GO nanoparticles, they were functionalized with CaP using standard process. The GO-CaP composite was not added to experimental adhesive (negative control group, GO-CaP-0%), and added at 2.5 and 5 wt% to yield GO-CaP-2.5% and GO-CaP 5% groups, respectively. Teeth were set to form bonded samples utilizing adhesives in three groups for SBS testing, with and without thermocycling. The homogenous diffusion of GO-CaP composite was verified in the adhesive. Resin tags having standard penetrations were observed on SEM micrographs. The EDX analysis confirmed the occurrence of calcium, phosphorus, and carbon ions in the composite containing adhesives. The SBS test revealed highest mean values for GO-CaP-5% followed by GO-CaP-2.5%. The FTIR spectra verified the presence of apatite peaks and the micro-Raman spectra showed characteristic D and G bands for GO nanoparticles. GO-CaP composite in dentin adhesive may improve its bond strength. The addition of 5 wt% resulted in a bond strength that was superior to all other groups. GO-CaP-5% group demonstrated lower DC (to control), uniform distribution of GO and CaP composite within adhesive, appropriate dentin interaction, and resin tag formation.

Synthesis and characterization of graphene oxide-zirconia (GO-ZrO2) and hydroxyapatite-zirconia (HA-ZrO2) nano-fillers for resin-based composites for load-bearing applications

OBJECTIVES

The study aims to synthesize two different types of nano-fillers based on zirconia (ZrO₂), which was functionalized with graphene oxide (GO-ZrO₂), and hydroxyapatite (HA-ZrO₂), and to implement them in an experimental methacrylate matrix containing new dimethacrylic oligomers.

METHODS

Nano-particles were synthesized via a modified Hummer's method and a sol-gel route. Bisphenol A-glycidyl methacrylate oligomers (Bis-GMA_336[0-1]) were synthesized from an epoxy resin that reacted with methacrylic acid in the presence of a basic catalyst. Traditional dental glass-fillers (Barium oxide/BaO and Barium fluoride/BaF₂) were synthesized to create an experimental resin-based composite (RBC) used as reference. Filler morphology was evaluated via Transmission Electron Microscopy. RBCs were characterised by real-time Fourier transform infrared spectroscopy (degree of cure/DC, polymerisation kinetics), real-time spectrometry (light transmittance), 3-point bending test (flexural strength and modulus, Weibull parameters), and depth-sensing indentation test (plastic and elastic deformation parameters).

RESULTS

The synthesized nanohybrid fillers proved good dispersing performance. Mechanical properties and materials' reliability are within or above the mean values reported in the literature for RBCs. Addition of HA-ZrO₂-fillers resulted in a decrease light transmission, DC and mechanical properties. Except for the HA-ZrO₂ RBC, materials showed a high resistance to softening in solvent.

CONCLUSIONS

The synthesis of GO-ZrO₂ and HA-ZrO₂ nanohybrid particles and their implementation in experimental RBCs has proven successful. Adjustments of the light transmission through suitable co-fillers in addition to GO-ZrO₂ as well as adjustments of the amount of HA-ZrO₂ are necessary to enable reduced curing time (<20 s).

CLINICAL SIGNIFICANCE

The addition of nanofillers with tailor-made properties can help improving the performance of modern restoratives.

Iron nanoparticle templates for constructing 3D graphene framework with enhanced performance in sodium-ion batteries

This study examines the synthesis and electrochemical performance of three-dimensional graphene for Li-ion batteries and Na-ion batteries. The in situ formation of iron hydroxide nanoparticles (Fe(OH)x NPs) of various weights on the surface of graphene oxide, followed by thermal treatment at elevated temperature and washing using hydrochloric acid, furnished 3D graphene. The characterization studies confirmed the prevention of graphene layer stacking by over 90% compared with thermal treatment without Fe(OH)x. The electrochemical performance of the 3D graphene was evaluated as a counter electrode for lithium metal and sodium metal in a half-cell configuration. This material showed good performances with a charging capacity of 507 mA h g-1 at 372 mA g-1 in Li-ion batteries and 252 mA h g-1 at 100 mA g-1 in Na-ion batteries, which is 1.4 and 1.9 times higher, respectively, than the graphene prepared without Fe(OH)x templates.