Graphene and its derivatives: Opportunities and challenges in dentistry

Graphene, sp2 hybridized carbon framework of one atom thickness, is reputed as the strongest material to date. It has marked its impact in manifold applications including electronics, sensors, composites, and catalysis. Current state-of-the-art graphene research revolves around its biomedical applications. The two-dimensional (2D) planar structure of graphene provides a large surface area for loading drugs/biomolecules and the possibility of conjugating fluorescent dyes for bioimaging. The high near-infrared absorbance makes graphene ideal for photothermal therapy. Henceforth, graphene turns out to be a reliable multifunctional material for use in diagnosis and treatment. It exhibits antibacterial property by directly interacting with the cell membrane. Potential application of graphene as a scaffold for the attachment and proliferation of stem cells and neuronal cells is captivating in a tissue regeneration scenario. Fabrication of 2D graphene into a 3D structure is made possible with the help of 3D printing, a revolutionary technology having promising applications in tissue and organ engineering. However, apart from its advantageous application scope, use of graphene raises toxicity concerns. Several reports have confirmed the potential toxicity of graphene and its derivatives, and the inconsistency may be due to the lack of standardized consensus protocols. The present review focuses on the hidden facts of graphene and its biomedical application, with special emphasis on drug delivery, biosensing, bioimaging, antibacterial, tissue engineering, and 3D printing applications.

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Comprehensive Application of Graphene: Emphasis on Biomedical Concerns

Graphene for the development of the next-generation of biocomposites for dental and medical applications

The world of dentistry is approaching graphene-based nanomaterials as substitutes for tissue engineering. Apart from its exceptional mechanical strength, electrical conductivity and thermal stability, graphene and its derivatives can be functionalized with several bioactive molecules. They can also be incorporated into different scaffolds used in regenerative dentistry, generating nanocomposites with improved characteristics. This review presents the state of the art of graphene-based nanomaterial applications in the dental field. We first discuss the interactions between cells and graphene, summarizing the available in vitro and in vivo studies concerning graphene biocompatibility and cytotoxicity. We then highlight the role of graphene-based nanomaterials in stem cell control, in terms of adhesion, proliferation and differentiation. Particular attention will be given to stem cells of dental origin, such as those isolated from dental pulp, periodontal ligament or dental follicle. The review then discusses the interactions between graphene-based nanomaterials with cells of the immune system; we also focus on the antibacterial activity of graphene nanomaterials. In the last section, we offer our perspectives on the various opportunities facing the use of graphene and its derivatives in associations with titanium dental implants, membranes for bone regeneration, resins, cements and adhesives as well as for tooth-whitening procedures.

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Graphene-Based Nanomaterials for Tissue Engineering in the Dental Field.

Significant efforts have been dedicated to fabricating favorable biomaterial-based bone substitutes for the repair of large bone defects. However, the development of bone biomaterials with suitable physiochemical and osteoinductive properties remains a challenge. Here, novel strontium-graphene oxide (Sr-GO) nanocomposites that allow long-term release of Sr ions are fabricated, which are used to reinforce collagen (Col) scaffolds through covalent cross-linking. The prepared Sr-GO-Col scaffold demonstrates significantly high water retention rates and excellent mechanical properties compared with unmodified Col scaffolds. The Sr-GO-modified Col scaffolds display a strong effect on adipose-derived stem cells by facilitating cell adhesion and osteogenic differentiation and by promoting the secretion of angiogenic factors to stimulate the in vitro tube formation of endothelial cells. Additionally, the secretion of angiogenic VEGF and osteogenic BMP-2 proteins is increased, which may be attributed to the synergistic effects of GO and Sr on the activation of the MAPK signaling pathway. The Sr-GO-Col constructs were then transplanted into rat critical-size calvarial bone defects, which showed the best bone regeneration and angiogenesis outcome at 12 weeks. Moreover, histological staining results show that the Sr-GO-Col group achieved complete defect bridging with the newly formed bone tissue and the residual Sr-GO nanoparticles are phagocytosed and degraded by multinucleated giant cells. These findings reveal that the incorporation of inorganic Sr-GO nanocomposites into biocompatible Col scaffolds is a viable strategy for fabricating favorable substitutes that enhance the regeneration of large bone defects.

Developing a Strontium-Releasing Graphene Oxide-/Collagen-Based Organic–Inorganic Nanobiocomposite for Large Bone Defect Regeneration via MAPK Signaling Pathway

Graphene oxide-based substrate: physical and surface characterization, cytocompatibility and differentiation potential of dental pulp stem cells

Bioactive calcium silicate cements are widely used to induce mineralization, to cement prosthetic parts, in the management of tooth perforations, and other areas Nonetheless, they can present clinical disadvantages, such as long setting time and modest physico-mechanical properties The objective of this work was to evaluate the potential of graphene nanosheets (GNS) to improve two bioactive cements GNS were obtained via reduction of graphite oxide GNS were mixed (1, 3, 5, and 7 wt %) with Biodentine (BIO) and Endocem Zr (ECZ), and the effects on setting time, hardness, push-out strength, pH profile, cell proliferation, and mineralization were evaluated Statistics were performed with two-way ANOVA and Tukey test (α = 005) GNS has not interfered in the composition of the set cements as confirmed by Raman, FT-IR and XRD GNS (1 and 3 wt %) shortened the setting time, increased hardness of both materials but decreased significantly the push-out strength of ECZ pH was not affected but 1 wt % and 7 wt % to ECZ and 5 wt % to BIO increased the mineralization compared to the controls In summary, GNS may be an alternative to improve the physico-mechanical properties and bioactivity of cements Nonetheless, the use of GNS may not be advised for all materials when effective bonding is a concern

Graphene Nanosheets to Improve Physico-Mechanical Properties of Bioactive Calcium Silicate Cements.

Tissue engineering is an interdisciplinary field that merges the principles of engineering, biology and material sciences to develop approaches and therapeutic strategies to restore, replace or improve biological functions. The development of biomaterials plays a pivotal role in the progress of tissue engineering. Carbon nanotubes (CNTs) and graphene with its derivatives (graphene oxide and reduced graphene oxide) are carbon-based materials that present unique physical, chemical and mechanical properties. Besides having unparalleled electrical and mechanical properties, they can be modified via noncovalent or covalent attachment of molecules. Due to these distinct characteristics, these materials are interesting candidates to be used for various biomedical applications such as drug and gene delivery, biosensing, bioimaging and beyond. In tissue engineering, CNTs and graphenes can be used alone as substrates or mixed with other biomaterials to increase their bioactivity hence improving stem cell attachment, proliferation and differentiation towards various phenotypes. Herein, the advances made in CNTs and graphenes for tissue engineering are presented with particular emphasis on their biocompatibility and potential for tissue engineering and regeneration research.

CHAPTER 12:Smart Carbon Nanotubes and Graphenes for Tissue Engineering

A correct diagnosis and understanding of the dynamics involved in root resorption is critical to effective management. Root resorption can be external (periodontally derived), internal (pulpally derived) or communicating in nature. External root resorption involving bone most often requires a multidisciplinary approach to treatment. Many innovative medicaments, bone grafts etc. have been introduced to achieve adequate results

External root resorption - A Case Report

Multiple mutilated teeth often pose a problem in endodontic isolation. This article introduces a simple and effective modification of one of the oldest techniques used for isolating multiple adjacent teeth requiring endodontic therapy where the teeth to be isolated were not amenable to traditional isolation procedures. The method used here is that of a custom fabrication of an acrylic retainer in conjunction with a conventional rubber dam. Photographs of a model and a clinical case are used to illustrate the method and clinical applicability.

http://www.kcdsjournal.com/pdf/2012.3.1.3.1.pdf

Sneha Sundar Rajan

Papers

Graphene oxide-based substrate: physical and surface characterization, cytocompatibility and differentiation potential of dental pulp stem cells

Graphene Nanosheets to Improve Physico-Mechanical Properties of Bioactive Calcium Silicate Cements.

CHAPTER 12:Smart Carbon Nanotubes and Graphenes for Tissue Engineering

External root resorption - A Case Report

A paradigm shift: An aid in the isolation of multiple mutilated teeth.