Graphene Oxide-Modified Polyetheretherketone with Excellent Antibacterial Properties and Biocompatibility for Implant Abutment

Surface modification strategies to reinforce the soft tissue seal at transmucosal region of dental implants

Soft tissue seal around the transmucosal region of dental implants is crucial for shielding oral bacterial invasion and guaranteeing the long-term functioning of implants. Compared with the robust periodontal tissue barrier around a natural tooth, the peri-implant mucosa presents a lower bonding efficiency to the transmucosal region of dental implants, due to physiological structural differences. As such, the weaker soft tissue seal around the transmucosal region can be easily broken by oral pathogens, which may stimulate serious inflammatory responses and lead to the development of peri-implant mucositis. Without timely treatment, the curable peri-implant mucositis would evolve into irreversible peri-implantitis, finally causing the failure of implantation. Herein, this review has summarized current surface modification strategies for the transmucosal region of dental implants with improved soft tissue bonding capacities (e.g., improving surface wettability, fabricating micro/nano topographies, altering the surface chemical composition and constructing bioactive coatings). Furthermore, the surfaces with advanced soft tissue bonding abilities can be incorporated with antibacterial properties to prevent infections, and/or with immunomodulatory designs to facilitate the establishment of soft tissue seal. Finally, we proposed future research orientations for developing multifunctional surfaces, thus establishing a firm soft tissue seal at the transmucosal region and achieving the long-term predictability of dental implants.

Enhanced Bacterial and Biofilm Adhesion Resistance of ALD Nano-TiO2 Coatings Compared to AO Coatings on Titanium Abutments

Purpose

The study was intended to compare the surface properties and the bacterial and biofilm adhesion resistance of two potential antibacterial nanometer titanium dioxide (nano-TiO2) coatings on dental titanium (Ti) abutments prepared by atomic layer deposition (ALD) and the anodic oxidation (AO) techniques.

Methods

Nano-TiO₂ coatings were developed using ALD and AO techniques and applied to Ti surfaces. The surface properties and the bacterial and biofilm adhesion resistance of these coatings were evaluated against commonly used Ti and Zirconia (ZrO₂) surfaces. The chemical compositions, crystalline forms, surface topography, roughness and hydrophilicity were characterized. The antibacterial performance was assessed by the scanning electron microscope (SEM), the Colony-forming unit (CFU) assay and the 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT) assay using in vitro models of Staphylococcus aureus (S. aureus), Streptococcus mutans (S. mutans), and Porphyromonas gingivalis (P. gingivalis) in both single- and mixed-species bacterial compositions.

Results

ALD-prepared nano-TiO₂ coatings resulted in a dense, smooth, and less hydrophilic surface with an anatase phase, significantly reducing the adhesion of the three bacteria by over 50%, comparable to ZrO₂. In contrast, AO-prepared coatings led to a less hydrophilic surface, characterized by various nano-sized pores within the oxide film. This alteration, however, had no impact on the adhesion of the three bacteria. The adhesion patterns for mixed-species bacteria were generally consistent with single-species results.

Conclusion

ALD-prepared nano-TiO₂ coatings on Ti abutments demonstrated promising antibacterial properties comparable to ZrO₂ surfaces, suggesting potential in preventing peri-implantitis. However, the bacterial and biofilm adhesion resistance of AO-produced nano-TiO₂ coatings was limited.

Osseointegrative and antimicrobial properties of graphene oxide nano coated dental implants: A systematic review

Introduction

Osseointegration stands as a pivotal concept within the realm of dental implants, signifying the intricate process through which a dental implant integrates with the adjoining bone tissue. Graphene oxide (GO) has been shown to promote osseointegration, the process by which the implant fuses with the surrounding bone. The objective of this study was to assess the osseointegrative and antimicrobial properties of GO nano coated dental implants.

Methods

A systematic search was conducted using electronic databases (e.g., PubMed, Scopus, Web of Science) to identify relevant studies published. Inclusion criteria encompassed studies that evaluated the effects of GO nano coating on osseointegrative and antimicrobial characteristics of dental implants. Studies not written in English and published before 2012 were excluded.

Results

The initial search yielded a total of 127 potential studies, of which six met the inclusion criteria and five were included in the review. These studies provided data on GO nano coated dental implants and their osseointegrative and antimicrobial properties. All the included studies showed moderate risk of bias. None of the studies provided information related to sample size calculation or sampling technique.

Discussion

The findings from the included studies demonstrated that GO nano coating had a positive impact on osseointegrative properties of dental implants. Enhanced bone-implant contact and increased bone density were observed in animals and humans receiving GO nano coated implants. Furthermore, the antimicrobial properties of GO nano coating were found to inhibit bacterial colonization and biofilm formation on the implant surface, reducing the risk of implant-associated infections.

Conclusion

The findings indicate that GO nano coating holds promise in enhancing the success rate and longevity of dental implants. However, more studies with larger sample sizes, are needed to further strengthen the evidence and determine the long-term effects of GO nano coated dental implants.

Graphene Oxide-Silver-Coated Sulfonated Polyetheretherketone (Ag/GO-SPEEK): A Broad-Spectrum Antibacterial Artificial Bone Implants

Polyetheretherketone (PEEK), particularly its sulfonated form (SPEEK), has emerged as a promising synthetic biomaterial for artificial bone implants, providing an alternative to conventional titanium metal. However, postoperative infections pose a critical challenge, driven by diverse and antibiotic-resistant bacteria. To address this issue, we propose the modification of the SPEEK surface using a thin graphene oxide (GO) film containing silver (Ag) ions. The resulting coating exhibits substantial antibacterial effects against various pathogens, including Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Candida albicans. Experimental assessments elucidate the coating's impact on bacterial adhesion, biofilm formation, and morphology. The results suggest that hindered bacterial growth stems from reduced biofilm production and the controlled release of Ag ions facilitated by the GO coating. The Ag/GO-SPEEK material holds promise as a bioactive implant, addressing the challenges associated with bacterial targeting in bone tissue engineering applications.

Graphene as a promising material in orthodontics: A review

Graphene is an extraordinary material with unique mechanical, chemical, and thermal properties. Additionally, it boasts high surface area and antimicrobial properties, making it an attractive option for researchers exploring innovative materials for biomedical applications. Although there have been various studies on graphene applications in different biomedical fields, limited reviews have been conducted on its use in dentistry, and no reviews have focused on its application in the orthodontic field. This review aims to present a comprehensive overview of graphene-based materials, with an emphasis on their antibacterial mechanisms and the factors that influence these properties. Additionally, the review summarizes the dental applications of graphene, spotlighting the studies of its orthodontic application as they can be used to enhance the antibacterial and mechanical properties of orthodontic materials such as adhesives, archwires, and splints. Also, they can be utilized to enhance bone remodeling during orthodontic tooth movement. An electronic search was carried out in Scopus, PubMed, Science Direct, and Wiley Online Library digital database platforms using graphene and orthodontics as keywords. The search was restricted to English language publications without a time limit. This review highlights the need for further laboratory and clinical research using graphene-based materials to improve the properties of orthodontic materials to make them available for clinical use.

A self-assembling graphene oxide coating for enhanced bactericidal and osteogenic properties of poly-ether-ether-ketone

Poly-ether-ether-ketone (PEEK) is a biomedical plastic that can be used for orthopedic implants, but it offers poor antibacterial properties and bioactivity. In this study, PEEK was sulfonated with the obtained porous structure adsorbing graphene oxide (GO). The surface microstructures and properties of the original PEEK, sulfonated PEEK (SPEEK), and GO-grafted PEEK (GO-SPEEK) were characterized. The results revealed that the GO-SPEEK surface is a 3D porous structure exhibiting superior hydrophilicity to the original PEEK. Although SPEEK was shown to possess antimicrobial properties against both Escherichia coli and Staphylococcus aureus, the bactericidal effect was even more significant for GO-SPEEK, at about 86% and 94%, respectively. In addition, the in vitro simulated-body-fluid immersion and cell experiments indicated that GO-SPEEK had much better hydroxyapatite (HA)-precipitation induction capacity and cell-material interactions (e.g., cell adhesion, proliferation, osteodifferentiation, and extracellular matrix mineralization. The tensile test revealed that the mechanical properties of PEEK were maintained after surface modification, as GO-SPEEK has comparable values of elastic modulus and tensile strength to PEEK. Our investigation sought a method to simultaneously endow PEEK with both good antimicrobial properties and bioactivity as well as mechanical properties, providing a theoretical basis for developing high-performance orthopedic implants in the clinic.

Decoration with electronegative 2D materials based on chemical transition layers on CFR-PEEK implants for promoting osteogenesis

Due to the unique lamellar structures, physicochemical and biological properties, electronegative two-dimensional (2D) materials have been explored for surface modification of carbon fibers reinforced polyetheretherketone (CFR-PEEK) composite. Deposition of electronegative 2D materials based on a porous surface created by concentrated H2SO4 has been studied to promote osteogenesis of CFR-PEEK. Generally, a porous layer will be pre-built on CFR-PEEK through severe corrosion of concentrated sulfuric acid to help the loading of 2D materials. However, the severe corrosion will greatly reduce surface mechanical strength, especially wear resistance and hardness, which increases the risk of collapse or even peeling of the bioactive coating by external force. Herein, instead of the severe corrosion, a mild corrosion by concentrated HNO3 was applied to modify the surface of CFR-PEEK to pre-create a dense transition layer for the further surface decoration of electronegative 2D materials (graphene oxide (GO) and black phosphorus (BP), representatively). The results indicated that hardness and wear resistance of the dense transition layer were markedly higher than those of the porous layer. Although GO and BP can be both loaded on these two transition layers, -SO3H on the porous transition layer showed moderate cytotoxicity, while -NO2 on the dense transition layer showed good cytocompatibility. The dense transition layer displayed higher mineralized deposition in vitro and new bone formation rate in vivo than the porous transition layer, moreover, GO and BP coatings improved osteogenesis. This work offers inspirations for the construction of electronegative 2D material coating on CFR-PEEK based on chemical transition layers.

Emerging strategies for combating Fusobacterium nucleatum in colorectal cancer treatment: Systematic review, improvements and future challenges

Colorectal cancer (CRC) is generally characterized by a high prevalence of Fusobacterium nucleatum (F. nucleatum), a spindle-shaped, Gram-negative anaerobe pathogen derived from the oral cavity. This tumor-resident microorganism has been closely correlated with the occurrence, progression, chemoresistance and immunosuppressive microenvironment of CRC. Furthermore, F. nucleatum can specifically colonize CRC tissues through adhesion on its surface, forming biofilms that are highly resistant to commonly used antibiotics. Accordingly, it is crucial to develop efficacious non-antibiotic approaches to eradicate F. nucleatum and its biofilms for CRC treatment. In recent years, various antimicrobial strategies, such as natural extracts, inorganic chemicals, organic chemicals, polymers, inorganic-organic hybrid materials, bacteriophages, probiotics, and vaccines, have been proposed to combat F. nucleatum and F. nucleatum biofilms. This review summarizes the latest advancements in anti-F. nucleatum research, elucidates the antimicrobial mechanisms employed by these systems, and discusses the benefits and drawbacks of each antimicrobial technology. Additionally, this review also provides an outlook on the antimicrobial specificity, potential clinical implications, challenges, and future improvements of these antimicrobial strategies in the treatment of CRC.

Mechanical properties and osteogenesis of CFR-PEEK composite with interface strengthening by graphene oxide for implant application

In this work, 1 wt% of graphite oxide (GO) was used to strengthen the interface of carbon fibers (CF) reinforced polyetheretherketone (CFR-PEEK) composites, so as to obtain sufficiently high mechanical properties and bioactive surfaces which are two fundamental requirements for orthopedic/dental implants. Concretely, aminated GO was grafted onto oxidized CF in aqueous solution in a mild and non-toxic manner, subsequently, the CF grafted by GO was used for injection molding to prepare CFR-PEEK implant. The dispersibility of CF in the composites were remarkably boosted. Mechanical tests indicated that the flexural strength, compressive strength and hardness of CFR-PEEK were increased by 51%, 46%, and 30%, respectively. Furthermore, the flexural modulus increased to 11.67 ± 0.20 GPa and the compression modulus increased to 6.12 ± 0.11 GPa, which both meet the elastic modulus of human bone (6-30 GPa). The wear resistance was slightly improved. In the in vitro cell evaluation, CFR-PEEK with interface strengthening by GO showed no cytotoxicity and exhibited significantly enhanced adhesion and proliferation of Bone marrow mesenchymal stem cells (BMSCs) on the surface. More importantly, osteogenesis-related protein expression in vitro and osteogenetic evaluation in vivo all disclosed greatly accelerated osteo-differentiation of BMSCs on the composites due to the additive effect of GO at the interface. Based on this scheme, the CFR-PEEK composites with the dual functions of mechanical enhancement and osteointegration promotion holds great potential as implants in orthopedic/dental applications.

Application of Graphene Oxide in Oral Surgery: A Systematic Review

The current review aims to provide an overview of the most recent research in the last 10 years on the potentials of graphene in the dental surgery field, focusing on the potential of graphene oxide (GO) applied to implant surfaces and prosthetic abutment surfaces, as well as to the membranes and scaffolds used in Guided Bone Regeneration (GBR) procedures. "Graphene oxide" and "dental surgery" and "dentistry" were the search terms utilized on the databases Scopus, Web of Science, and Pubmed, with the Boolean operator "AND" and "OR". Reviewers worked in pairs to select studies based on specific inclusion and exclusion criteria. They included animal studies, clinical studies, or case reports, and in vitro and in vivo studies. However, they excluded systematic reviews, narrative reviews, and meta-analyses. Results: Of these 293 studies, 19 publications were included in this review. The field of graphene-based engineered nanomaterials in dentistry is expanding. Aside from its superior mechanical properties, electrical conductivity, and thermal stability, graphene and its derivatives may be functionalized with a variety of bioactive compounds, allowing them to be introduced into and improved upon various scaffolds used in regenerative dentistry. This review presents state-of-the-art graphene-based dental surgery applications. Even if further studies and investigations are still needed, the GO coating could improve clinical results in the examined dental surgery fields. Better osseointegration, as well as increased antibacterial and cytocompatible qualities, can benefit GO-coated implant surgery. On bacterially contaminated implant abutment surfaces, the CO coating may provide the optimum prospects for soft tissue sealing to occur. GBR proves to be a safe and stable material, improving both bone regeneration when using GO-enhanced graft materials as well as biocompatibility and mechanical properties of GO-incorporated membranes.

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.

Smart dental materials for antimicrobial applications

Smart biomaterials can sense and react to physiological or external environmental stimuli (e.g., mechanical, chemical, electrical, or magnetic signals). The last decades have seen exponential growth in the use and development of smart dental biomaterials for antimicrobial applications in dentistry. These biomaterial systems offer improved efficacy and controllable bio-functionalities to prevent infections and extend the longevity of dental devices. This review article presents the current state-of-the-art of design, evaluation, advantages, and limitations of bioactive and stimuli-responsive and autonomous dental materials for antimicrobial applications. First, the importance and classification of smart biomaterials are discussed. Second, the categories of bioresponsive antibacterial dental materials are systematically itemized based on different stimuli, including pH, enzymes, light, magnetic field, and vibrations. For each category, their antimicrobial mechanism, applications, and examples are discussed. Finally, we examined the limitations and obstacles required to develop clinically relevant applications of these appealing technologies.

Graphene and its derivatives: "one stone, three birds" strategy for orthopedic implant-associated infections

Orthopedic implants provide an avascular surface for microbial attachment and biofilm formation, impeding the entry of immune cells and the diffusion of antibiotics. The above is an important cause of dental and orthopedic implant-associated infection (IAI). For the prevention and treatment of IAI, the drawbacks of antibiotic resistance and surgical treatment are increasingly apparent. Due to their outstanding biological properties such as biocompatibility, immunomodulatory effects, and antibacterial properties, graphene-based nanomaterials (GBNs) have been applied to bone tissue engineering to deal with IAI, and in particular have great potential application in drug/gene carriers, multi-functional platforms, and coating forms. Here we review the latest research progress and achievements in GBNs for the prevention and treatment of IAI, mainly including their biomedical applications for antibacterial and immunomodulation effects, and for inducing osteogenesis. Furthermore, the biosafety of graphene family materials in bone tissue regeneration and the feasibility of clinical application are critically analyzed and discussed.

Nanomaterial-Based Electrically Conductive Hydrogels for Cardiac Tissue Repair

Cardiovascular disease is one of major causes of deaths, and its incidence has gradually increased worldwide. For cardiovascular diseases, several therapeutic approaches, such as drugs, cell-based therapy, and heart transplantation, are currently employed; however, their therapeutic efficacy and/or practical availability are still limited. Recently, biomaterial-based tissue engineering approaches have been recognized as promising for regenerating cardiac function in patients with cardiovascular diseases, including myocardial infarction (MI). In particular, materials mimicking the characteristics of native cardiac tissues can potentially prevent pathological progression and promote cardiac repair of the heart tissues post-MI. The mechanical (softness) and electrical (conductivity) properties of biomaterials as non-biochemical cues can improve the cardiac functions of infarcted hearts by mitigating myocardial cell death and subsequent fibrosis, which often leads to cardiac tissue stiffening and high electrical resistance. Consequently, electrically conductive hydrogels that can provide mechanical strength and augment the electrical activity of the infarcted heart tissue are considered new functional materials capable of mitigating the pathological progression to heart failure and stimulating cardiac regeneration. In this review, we highlight nanomaterial-incorporated hydrogels that can induce cardiac repair after MI. Nanomaterials, including carbon-based nanomaterials and recently discovered two-dimensional nanomaterials, offer great opportunities for developing functional conductive hydrogels owing to their excellent electrical conductivity, large surface area, and ease of modification. We describe recent results using nanomaterial-incorporated conductive hydrogels as cardiac patches and injectable hydrogels for cardiac repair. While further evaluations are required to confirm the therapeutic efficacy and toxicity of these materials, they could potentially be used for the regeneration of other electrically active tissues, such as nerves and muscles.

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.

Titanium Surfaces Modified with Graphene Oxide/Gelatin Composite Coatings for Enhanced Antibacterial Properties and Biological Activities

Titanium alloys have been widely used in orthopedic implants due to their excellent physicochemical properties and good biocompatibility. However, in practice, titanium implants may fail to integrate or develop an implant-centered infection. Because of its excellent mechanical properties, bone integrability, biocompatibility, antibacterial properties, and so on, graphene oxide is increasingly being used in the preparation of composite biomaterials. The percutaneous titanium implants are used as the research object in this project. To solve the integration of implant and tissue, a graphene oxide/gelatin (GO/gel) composite coating was used to optimize the implant surface. Bacterial and cell experiments were used to investigate the antimicrobial activity, biocompatibility, and regulation of macrophage polarization of GO/gel-modified titanium. According to our findings, GO/gel-modified titanium has a good bacteriostatic effect against Staphylococcus aureus. On the modified surface, L929 cells proliferated well and showed no cytotoxicity. Simultaneously, the GO/gel-modified titanium surface could inhibit macrophage adhesion and spread in the early stage of culture and showed a more obvious inflammatory decline in the late stage of culture. These findings implied that GO/gel-modified titanium is advantageous for resistant bacteria and tissue remolding.

Graphene oxide and mineralized collagen-functionalized dental implant abutment with effective soft tissue seal and romotely repeatable photodisinfection

Grasping the boundary of antibacterial function may be better for the sealing of soft tissue around dental implant abutment. Inspired by ‘overdone is worse than undone’, we prepared a sandwich-structured dental implant coating on the percutaneous part using graphene oxide (GO) wrapped under mineralized collagen. Our unique coating structure ensured the high photothermal conversion capability and good photothermal stability of GO. The prepared coating not only achieved suitable inhibition on colonizing bacteria growth of Streptococcus sanguinis, Fusobacterium nucleatum and Porphyromonas gingivalis but also disrupted the wall/membrane permeability of free bacteria. Further enhancements on the antibacterial property were generally observed through the additional incorporation of dimethylaminododecyl methacrylate. Additionally, the coating with sandwich structure significantly enhanced the adhesion, cytoskeleton organization and proliferation of human gingival fibroblasts, which was effective to improve soft tissue sealing. Furthermore, cell viability was preserved when cells and bacteria were cultivated in the same environment by a coculture assay. This was attributed to the sandwich structure and mineralized collagen as the outmost layer, which would protect tissue cells from photothermal therapy and GO, as well as accelerate the recovery of cell activity. Overall, the coating design would provide a useful alternative method for dental implant abutment surface modification and functionalization.