Field Of Regenerative Endodontics Research Articles

Effects of Growth Factors on the Differentiation of Dental Stem Cells: A Systematic Review and Meta-analysis (Part I).

To evaluate the biological interaction between dental stem cells (DSCs) and different growth factors in the field of regenerative endodontics. A systematic search was conducted in the electronic databases up to October 2021. This study followed the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Ex vivo studies evaluating the biological interactions of DSCs and growth factors were included. The meta-analysis was performed according to the type of growth factor. The outcomes were cell viability/ proliferation and mineralization. Standardized mean differences (SMDs) were estimated using the random-effect maximum-likelihood method (P < .05). Additional analysis was performed to find any potential source of heterogeneity. Twenty articles were included in the systematic review; meta-analysis was performed for fibroblast growth factor-2 (FGF-2) and Transforming growth factor-ß1 (TGF-β1) (n = 5). Results showed that use of FGF-2 significantly increased cell proliferation on day 1-(SMD = 3.56, P = 0.00), 3-(SMD = 9.04, P = 0.00), 5-(SMD = 8.37, P = 0.01), and 7 (SMD=8.51, P=0.00) than the control group. TGF-ß1 increased alkaline phosphatase (ALP) activity more than control only on day 3 (SMD = 3.68, P = 0.02). TGF-β1 had no significant effect on cell proliferation on days 1 and 3 (P > 0.05) and on ALP activity on days 5 and 7 (P > 0.05). Meta-regression analysis showed that different covariates (i.e., cell type, passage number, and growth factors' concentration) could significantly influence the effect sizes at different follow- ups (P < 0.05). Specific growth factors might enhance the proliferation and mineralization of DSCs; however, the obtained evidence was weak. Due to the high heterogeneity among the included studies, other growth factors' inhibitory/stimulatory effects on DSCs could not be evaluated.

Current Aspects of Regenerative Endodontics: A Systematic Review

Relevance. The modern concept of endodontic treatment in most clinical cases involves extirpation of the pulp with the loss of its plastic, trophic, sensory, and protective functions. In this regard, the search for ways to recreate lost cells and the main substance of the pulp and periodontium to replace the intraradicular space with “vital” tissue. Regenerative endodontics based on the principles of tissue engineering and offers techniques for restoring damaged tissues of the pulp-dentin complex based on the use of stem cells, growth factors, and an organic matrix. Aim. Systematize information presented in scientific articles about research conducted, opportunities and development prospects in the field of regenerative endodontics. Materials and methods. A search of literature sources was carried out in the PubMed, dissercat.com, elibrary database.ru, cyberleninka.ru, by keywords, “regenerative endodontics”, “stem cells”, “growth factors”, “pulp-dentin complex” with a choice of article types “Clinical Trial”, “Meta-Analysis”, “Review”, "Systematic Review". Results. After analyzing the literature review, an idea was obtained about the current stage of development of regenerative endodontics, preclinical and clinical studies on the restoration of the pulp-dentin complex. Clinical cases based on the triad of regenerative endodontics are presented, as well as an algorithm for performing these therapeutic procedures. Conclusions. Regenerative endodontics is a rapidly developing discipline whose clinical advances are primarily related to the treatment of immature tooth roots, which results in continued root development. Subsequent scientific research is aimed at obtaining significant results in the treatment of a fully formed permanent tooth, which will ensure a unique restoration of the immunological, sensory and protective properties of the pulp-dentine complex.

Application of Stem Cells in Endodontics

The discovery of stem cells in dental pulp has expanded our understanding concerning the various mechanisms that play a substantial role in the maintenance of dental pulp homeostasis to improve health and also regarding the pulp response to injury. Stems cells play a pivotal role in the physiology of the dental pulp tissue throughout the entire lifespan of the tooth. The ideology that these cells are intimately associated with regulating pulp angiogenesis as a response to cariogenic challenges is also inferred. In recent times, we are witnessing an increasing number of passionate individuals showing enthusiasm in the field of regenerative endodontics as stem cells exhibit potential benefits in dental pulp tissue engineering. The article here focuses predominantly on stem cells—the dental stem cells and non-dental stem cells which play an active part in benefitting pulpal necrosis tooth, the cardinal objective of these cells in the field of endodontic therapy, and the current, as well as the future role, stem cells could play in the clinical practice of endodontics eventually. Keywords: Dental stem cells, Pulpal necrosis, Stem cells, Regenerative.

Micro-RNA Profiling in Dental Pulp Cell Cultures.

Recently, the central role of microRNAs (miRNAs) and epigenetic modifiers in biological and pathological processes, such as stem cell differentiation and inflammation, has stimulated interest. In particular, their influence in dental pulp stem cell (DPSC) differentiation has been highlighted as an exciting avenue of research in the field of Regenerative Endodontics. Although specific miRNAs have been shown to be altered in expression during dental pulp mineralization and repair processes, their interaction with epigenetic modifiers, such as histone deacetylase inhibitors (HDACi) or DNA methyltransferase inhibitors (DNMTi), has not been explored. Currently available next-generation sequencing (NGS) technologies offer the potential to explore in detail the miRNA expression profile of cells, and to investigate the effects of pharmacological inhibitors such as epigenetic modifiers on this profile. This chapter describes the experimental methods required to induce mineralization of DPCs in the presence and absence of epigenetic modifiers and analyze the resulting miRNA expression profiles using RNA sequencing (RNAseq), with a focus on bioinformatic analysis.

The Potential Translational Applications of Nanoparticles in Endodontics.

Nanotechnology has substantially progressed in the past decades, giving rise to numerous possible applications in different biomedical fields. In particular, the use of nanoparticles in endodontics has generated significant interest due to their unique characteristics. As a result of their nanoscale dimensions, nanoparticles possess several properties that may enhance the treatment of endodontic infections, such as heightened antibacterial activity, increased reactivity and the capacity to be functionalized with other reactive compounds. Effective disinfection and sealing of the root canal system are the hallmarks for successful endodontic treatment. However, the presence of bacterial biofilms and resistance to endodontic disinfectants pose a significant challenge to this goal. This has encouraged the investigation of antibacterial nanoparticle-based irrigants and intracanal medicaments, which may improve the elimination of endodontic infections. In addition, photosynthesizer-functionalized nanoparticles could also serve as a worthy adjunct to root canal disinfection strategies. Furthermore, despite the myriad of commercially available options for endodontic obturation, the “ideal” material has yet to be conceived. This has led to the development of various experimental nanoparticle-incorporated obturation materials and sealers that exhibit a range of favourable physicochemical properties including enhanced antibacterial efficacy and bioactivity. Nanoparticle applications also show promise in the field of regenerative endodontics, such as supporting the release of bioactive molecules and enhancing the biophysical properties of scaffolds. Given the constantly growing body of research in this field, this article aims to present an overview of the current evidence pertaining to the potential translational applications of nanoparticles in endodontics.

L-mimosine and hypoxia can increase angiogenin production in dental pulp-derived cells

BackgroundAngiogenin is a key molecule in the healing process which has been successfully applied in the field of regenerative medicine. The role of angiogenin in dental pulp regeneration is unclear. Here we aimed to reveal the impact of the hypoxia mimetic agent L-mimosine (L-MIM) and hypoxia on angiogenin in the dental pulp.MethodsHuman dental pulp-derived cells (DPC) were cultured in monolayer and spheroid cultures and treated with L-MIM or hypoxia. In addition, tooth slice organ cultures were applied to mimic the pulp-dentin complex. We measured angiogenin mRNA and protein levels using qPCR and ELISA, respectively. Inhibitor studies with echinomycin were performed to reveal the role of hypoxia-inducible factor (HIF)-1 signaling.ResultsBoth, L-MIM and hypoxia increased the production of angiogenin at the protein level in monolayer cultures of DPC, while the increase at the mRNA level did not reach the level of significance. The increase of angiogenin in response to treatment with L-MIM or hypoxia was reduced by echinomycin. In spheroid cultures, L-MIM increased angiogenin at protein levels while the effect of hypoxia was not significant. Angiogenin was also expressed and released in tooth slice organ cultures under normoxic and hypoxic conditions and in the presence of L-MIM.ConclusionsL-MIM and hypoxia modulate production of angiogenin via HIF-1 differentially and the response depends on the culture model. Given the role of angiogenin in regeneration the here presented results are of high relevance for pre-conditioning approaches for cell therapy and tissue engineering in the field of regenerative endodontics.

Pulp regeneration in a full-length human tooth root using a hierarchical nanofibrous microsphere system

While pulp regeneration using tissue engineering strategy has been explored for over a decade, successful regeneration of pulp tissues in a full-length human root with a one-end seal that truly simulates clinical endodontic treatment has not been achieved. To address this challenge, we designed and synthesized a unique hierarchical growth factor-loaded nanofibrous microsphere scaffolding system. In this system, vascular endothelial growth factor (VEGF) binds with heparin and is encapsulated in heparin-conjugated gelatin nanospheres, which are further immobilized in the nanofibers of an injectable poly(l-lactic acid) (PLLA) microsphere. This hierarchical microsphere system not only protects the VEGF from denaturation and degradation, but also provides excellent control of its sustained release. In addition, the nanofibrous PLLA microsphere integrates the extracellular matrix-mimicking architecture with a highly porous injectable form, efficiently accommodating dental pulp stem cells (DPSCs) and supporting their proliferation and pulp tissue formation. Our in vivo study showed the successful regeneration of pulp-like tissues that fulfilled the entire apical and middle thirds and reached the coronal third of the full-length root canal. In addition, a large number of blood vessels were regenerated throughout the canal. For the first time, our work demonstrates the success of pulp tissue regeneration in a full-length root canal, making it a significant step toward regenerative endodontics. Statement of SignificanceThe regeneration of pulp tissues in a full-length tooth root canal has been one of the greatest challenges in the field of regenerative endodontics, and one of the biggest barriers for its clinical application. In this study, we developed a unique approach to tackle this challenge, and for the first time, we successfully regenerated living pulp tissues in a full-length root canal, making it a significant step toward regenerative endodontics.This study will make positive scientific impact and interest the broad and multidisciplinary readership in the dental biomaterials and craniofacial tissue engineering community.

Dental pulp regeneration

Trauma in the oral region and tooth avulsion are a major part of injuries in children, adolescents, and young adults. Established methods used to manage these cases provide mainly repair, but not regeneration. Tissue engineering paves the way for research in the new field of regenerative endodontics to overcome the limits of conservative strategies. This review aims to provide an overview of the available in vitro and in vivo models for dental pulp regeneration. The review covers different in vitro models, including two- and three-dimensional models and organ cultures, comprising both ectopic and orthotopic approaches. These models show the great potential of tissue engineering for regenerative endodontics, which can lead to regeneration of the pulp–dentin complex in future.

Non-autologous endodontic pulp regeneration approach in molar teeth of the rat

The dental pulp is an important soft connective tissue which is able to produce dentin over time as a reaction on external stimuli. It also maintains the biological and physiological vitality of the dentin. Due to this the pulp is essential for teeth homeostasis. However, dental caries is still one of the most prevalent health problems in dentistry and therefore, one major cause for early loss of the dental pulp vitality and subsequent tooth extractions. Meanwhile the potential for successful pulp regeneration therapy is increasing due to advances in the field of regenerative endodontics. Thus, adequate experimental animal models are required for testing and validating these new regenerative therapies. Rodents and rats in particular, are relevant models for experimental periodontal research. The breeding and housing costs of rats are relatively low facilitating studies with sufficient numbers for statistical analysis in comparison to bigger sized mammals like beagle dogs, miniature pigs or monkeys. Additionally, rat molar teeth and pulps are characterized by similar anatomical, histological, biological and physiological features to human teeth. Essential biological reactions of the pulp tissue and the interaction during the different stages of wound healing of rat molar teeth are comparable to that of other mammals. However, despite of the multiple research activities in the field of regenerative endodontics and the above mentioned advantages of the rat model only rare in vivo studies are published. Therefore, the presented study aimed to introduce the rat molar teeth as a valid model for studying dental pulp stem cell based endodontic tissue regeneration. Human dental pulp stem cells were implanted into the pulp of immunodeficient rats (RNU rats). Cell growth was supported by a collagenous membrane, which was applied on top of the cells after implantation. After closing the pulpal cavity with a light-polymerisable resin human dental pulp stem cells were able to maintain cell viability in the rat molar pulp niche for at least three weeks. This demonstrated the suitability of immunodeficient RNU rats for non-autologous dental stem cell based endodontic tissue engineering approaches.

Missing Concepts in De Novo Pulp Regeneration

Regenerative endodontics has gained much attention in the past decade because it offers an alternative approach in treating endodontically involved teeth. Instead of filling the canal space with artificial materials, it attempts to fill the canal with vital tissues. The objective of regeneration is to regain the tissue and restore its function to the original state. In terms of pulp regeneration, a clinical protocol that intends to reestablish pulp/dentin tissues in the canal space has been developed—termed revitalization or revascularization. Histologic studies from animal and human teeth receiving revitalization have shown that pulp regeneration is difficult to achieve. In tissue engineering, there are 2 approaches to regeneration tissues: cell based and cell free. The former involves transplanting exogenous cells into the host, and the latter does not. Revitalization belongs to the latter approach. A number of crucial concepts have not been well discussed, noted, or understood in the field of regenerative endodontics in terms of pulp/dentin regeneration: (1) critical size defect of dentin and pulp, (2) cell lineage commitment to odontoblasts, (3) regeneration vs. repair, and (4) hurdles of cell-based pulp regeneration for clinical applications. This review article elaborates on these missing concepts and analyzes them at their cellular and molecular levels, which will in part explain why the non-cell-based revitalization procedure is difficult to establish pulp/dentin regeneration. Although the cell-based approach has been proven to regenerate pulp/dentin, such an approach will face barriers—with the key hurdle being the shortage of the current good manufacturing practice facilities, discussed herein.